A nanoporous ruthenium oxide framework for amperometric sensing of glucose and potentiometric sensing of pH

Nanoporous ruthenium oxide frameworks (L 2-eRuO) were electrodeposited on gold substrates by repetitive potential cycling in solutions of ruthenium(III) ions in the presence of reverse neutral micelles. The L 2-eRuO was characterized in terms of direct oxidation of glucose and potentiometric response to pH values. The surface structures and morphologies of the L 2-eRuO were characterized by scanning electron microscopy, energy dispersive X-ray spectroscopy, Raman spectroscopy, and high-resolution transmission electron microscopy. Their surface area was estimated via underpotential deposition of copper. L 2-eRuO-modified electrodes showed a 17-fold higher sensitivity (40 μA mM -1 cm -2 towards glucose in 0-4 mM concentration in solution of pH 7.4) than a RuO electrode prepared in the absence of reverse micelles. Potential interferents such as ascorbic acid, 4-acetamidophenol, uric acid and dopamine displayed no effect. The new electrode also revealed improved potentiometric response to pH changes compared to a platinum electrode of the same type. © 2012 Springer-Verlag

Electrocatalytic activity of nanoporous Pd and Pt: Effect of structural features

The electrocatalytic activities of nanoporous palladium (npPd) and platinum (npPt) for oxygen reduction reaction (ORR) under alkaline conditions and hydrogen peroxide electrochemical reactions under neutral conditions were examined. npPd and npPt were prepared by the electrochemical deposition of each metal from the corresponding metal precursor in the presence of reverse micelles of Triton X-100, directing highly porous microstructures. The nanoporous catalysts showed excellent electrocatalytic activity for both the ORR and hydrogen peroxide electrochemical oxidation/reduction due to the increased active surface area. In particular, the npPd exhibited superior ORR activity (i.e., more positive onset and half-wave potentials, higher current density and greater number of electrons transferred) despite the smaller roughness factor than the npPt and commercial Pt. The catalytic activity for the hydrogen peroxide electrochemical reactions was also higher while using npPd (i.e., faster electrode reaction kinetics, increased current densities, etc.) compared to npPt. The higher catalytic activity of npPd than that of npPt suggests an advantage of the unique npPd structure, composed of nano- as well as micro-porosity, in facilitating mass transport through the porous metal layer. The npPd exhibited amperometric current responses, induced by the oxidation as well as reduction of hydrogen peroxide, linearly proportional to the hydrogen peroxide concentration with a rapid response time (<∼2 s), high sensitivity, and low detection limit (<1.8 μM). © 2011 The Owner Societies

Hierarchically driven IrO 2 nanowire electrocatalysts for direct sensing of biomolecules

Applying nanoscale device fabrications toward biomolecules, ultra sensitive, selective, robust, and reliable chemical or biological microsensors have been one of the most fascinating research directions in our life science. Here we introduce hierarchically driven iridium dioxide (IrO 2) nanowires directly on a platinum (Pt) microwire, which allows a simple fabrication of the amperometric sensor and shows a favorable electronic property desired for sensing of hydrogen peroxide (H 2O 2) and dihydronicotinamide adenine dinucleotide (NADH) without the aid of enzymes. This rational engineering of a nanoscale architecture based on the direct formation of the hierarchical 1-dimensional (1-D) nanostructures on an electrode can offer a useful platform for high-performance electrochemical biosensors, enabling the efficient, ultrasensitive detection of biologically important molecules. © 2012 American Chemical Society

Growth of highly single crystalline IrO 2 nanowires and their electrochemical applications

We present the facile growth of highly single crystalline iridium dioxide (IrO 2) nanowires on SiO 2/Si and Au substrates via a simple vapor phase transport process under atmospheric pressure without any catalyst. Particularly, high-density needle-like IrO 2 nanowires were readily obtained on a single Au microwire, suggesting that the melted surface layer of Au might effectively enhance the nucleation of gaseous IrO 3 precursors at the growth temperature. In addition, all the electrochemical observations of the directly grown IrO 2 nanowires on a single Au microwire support favorable electron-transfer kinetics of [Fe(CN 6)] 4-/3- as well as Ru(NH 3) 63+/2+ at the highly oriented crystalline IrO 2 nanowire surface. Furthermore, stable pH response is shown, revealing potential for use as a miniaturized pH sensor, confirmed by the calibration curve exhibiting super-Nernstian behavior with a slope of 71.6 mV pH -1. © 2012 American Chemical Society

Single carbon fiber decorated with RuO 2 nanorods as a highly electrocatalytic sensing element

We demonstrate highly efficient electocatalytic activities of single crystalline RuO 2 nanorods grown on carbon fiber (CF), i.e., RuO 2 nanorod-CF hybrid microelectrode, prepared by a simple thermal annealing process from the Ru(OH) 3 precursor at 300 °C. The general electrochemical activity of a RuO 2 nanorod-CF microelectrode represents faster electron transfer for the [Fe(CN) 6] 3-/4- couple than that of the bare CF microelectrode which are confirmed from the cyclic voltammetry (CV) measurement. Also, the amperometric response for the H 2O 2 oxidation is remarkably facilitated at the RuO 2 nanorod-CF microelectrode by not only the enlarged surface area but the high electrocatalytic activity of the RuO 2 nanorod material itself. Furthermore, a single microelectrode of RuO 2 nanorod-CF exhibits the superior tolerance to Cl - ion poisoning unlike Pt-based electrocatalysts, indicating the promising sensor candidate in physiological conditions. © 2012 American Chemical Society

The Medici Effect: Multidisciplinary Insights for Entrepreneurship Research

No description supplie

The Medici Effect: Multidisciplinary Insights for Entrepreneurship Research

No description supplie

Nonenzymatic amperometric sensor for ascorbic acid based on hollow gold/ruthenium nanoshells

We report a new nonenzymatic amperometric detection of ascorbic acid (AA) using a glassy carbon (GC) disk electrode modified with hollow gold/ruthenium (hAu-Ru) nanoshells, which exhibited decent sensing characteristics. The hAu-Ru nanoshells were prepared by the incorporation of Ru on hollow gold (hAu) nanoshells from Co nanoparticle templates, which enabled AA selectivity against glucose without aid of enzyme or membrane. The structure and electrocatalytic activities of the hAu-Ru catalysts were characterized by spectroscopic and electrochemical techniques. The hAu-Ru loaded on GC electrode (hAu-Ru/GC) showed sensitivity of 426μAmM-1cm-2 (normalized to the GC disk area) for the linear dynamic range of <5μM to 2mM AA at physiological pH. The response time and detection limit were 1.6s and 2.2μM, respectively. Furthermore, the hAu-Ru/GC electrode displayed remarkable selectivity for ascorbic acid over all potential biological interferents, including glucose, uric acid (UA), dopamine (DA), 4-acetamidophenol (AP), and nicotinamide adenine dinucleotide (NADH), which could be especially good for biological sensing. © 2014 Elsevier B.V

OGLE-2016-BLG-1190Lb: The First Spitzer Bulge Planet Lies Near the Planet/Brown-dwarf Boundary

We report the discovery of OGLE-2016-BLG-1190Lb, which is likely to be the first Spitzer microlensing planet in the Galactic bulge/bar, an assignation that can be confirmed by two epochs of high-resolution imaging of the combined source-lens baseline object. The planet's mass, Mp= 13.4 ± 0.9 MJ, places it right at the deuterium-burning limit, i.e., the conventional boundary between "planets" and "brown dwarfs." Its existence raises the question of whether such objects are really "planets" (formed within the disks of their hosts) or "failed stars" (low-mass objects formed by gas fragmentation). This question may ultimately be addressed by comparing disk and bulge/bar planets, which is a goal of the Spitzer microlens program. The host is a G dwarf, Mhost= 0.89 ± 0.07 Mo, and the planet has a semimajor axis a ∼ 2.0 au. We use Kepler K2 Campaign 9 microlensing data to break the lens-mass degeneracy that generically impacts parallax solutions from Earth-Spitzer observations alone, which is the first successful application of this approach. The microlensing data, derived primarily from near-continuous, ultradense survey observations from OGLE, MOA, and three KMTNet telescopes, contain more orbital information than for any previous microlensing planet, but not quite enough to accurately specify the full orbit. However, these data do permit the first rigorous test of microlensing orbital-motion measurements, which are typically derived from data taken over <1% of an orbital period

COVIDiSTRESS diverse dataset on psychological and behavioural outcomes one year into the COVID-19 pandemic

During the onset of the COVID-19 pandemic, the COVIDiSTRESS Consortium launched an open-access global survey to understand and improve individuals’ experiences related to the crisis. A year later, we extended this line of research by launching a new survey to address the dynamic landscape of the pandemic. This survey was released with the goal of addressing diversity, equity, and inclusion by working with over 150 researchers across the globe who collected data in 48 languages and dialects across 137 countries. The resulting cleaned dataset described here includes 15,740 of over 20,000 responses. The dataset allows cross-cultural study of psychological wellbeing and behaviours a year into the pandemic. It includes measures of stress, resilience, vaccine attitudes, trust in government and scientists, compliance, and information acquisition and misperceptions regarding COVID-19. Open-access raw and cleaned datasets with computed scores are available. Just as our initial COVIDiSTRESS dataset has facilitated government policy decisions regarding health crises, this dataset can be used by researchers and policy makers to inform research, decisions, and policy