Electrocatalysis of oxygen reduction by quinones adsorbed on highly oriented pyrolytic graphite electrodes

The reduction of oxygen in alkaline solution has been studied on highly oriented pyrolytic graphite (HOPG) electrodes modified with various quinones using a rotating disk electrode (RDE). The electrode surface was modified by adsorption of quinones from a 0.1 M KOH solution. The oxygen reduction activity of these electrodes was considerably higher than that for unmodified HOPG and characteristic current maxima for oxygen reduction was observed. All quinones studied catalysed the two-electron reduction of oxygen to hydrogen peroxide. The peak potentials for oxygen reduction were in good correlation with the redox potentials of the quinones that were found from the cyclic voltammograms in oxygen-free solutions. The results obtained give further evidence that oxygen reduction is catalysed by the semiquinone radical and that the redox potential of the quinone is the most important factor determining its electrocatalytic activity for oxygen reduction.     

A 2.5-GFLOPS, 6.5 million polygons per second, four-way VLIWgeometry processor with SIMD instructions and a software bypassmechanism

A four-way very long instruction word (VLIW), 312-MHz geometry processor with peripheral component interconnect/accelerated graphic port bus bridge was implemented in a 0.21-μm, 2.5-V, three-layer-metal CMOS process. We adopted (1) a software bypass mechanism, (2) single-instruction multiple-data stream instructions, (3) four sets of floating-point multiply add and accumulate execution units, (4) special condition code registers and a branch condition generator for a clipping operation, and (5) automatic clock delay tuning methodology. As a result of these features, we achieved a performance of 2.5 GFLOPS and 6.5 million polygons per second for a three-dimensional geometry processor, which is the highest published performance as a single geometry processor. The processor is applicable to computer-aided-design systems that require very high graphics performance     

Long Residence Times Revealed by Aurora A Kinase‐Targeting Fluorescent Probes Derived from Inhibitors MLN8237 and VX‐689

We report the development of three fluorescent probes for protein kinase Aurora A that are derived from the well‐known inhibitors MLN8237 and VX‐689 (MK‐5108). Two of these probes target the ATP site of Aurora A, and one targets simultaneously the ATP and substrate sites of the kinase. The probes were tested in an assay with fluorescence polarisation/anisotropy readout, and we demonstrated slow association kinetics and long residence time of the probes (k_on 10⁵–10⁷ M ^?1 s^?1, k_off 10^?3–10^?4 s^?1; residence time 500–3000 s). The presence of the Aurora A activator TPX2 caused a significant reduction in the on‐rate and increase in the off‐rate of fluorescent probes targeting ATP site. These observations were supported by Aurora A inhibition assays with MLN8237 and VX‐689. Overall, our results emphasise the importance of rational design of experiments with these compounds and correct interpretation of the obtained data.     

Successful immunotherapy of the highly metastatic murine ESb lymphoma with sensitized CD8+ T cells and IFN-alpha/beta

Daily IFN-alpha/beta therapy was totally ineffective in inhibiting the development of visceral metastases in DBA/2 mice injected i.v. with the ESb lymphoma regardless of the number of tumor cells injected. The finding that IFN-alpha/beta therapy increased the survival time of ESb-immunized mice rechallenged with ESb cells suggested that cooperation between the immune system and IFN-alpha/beta was important. Adoptive transfer of Esb-immune spleen cells (but not normal cells) together with IFN-alpha/beta treatment did inhibit the development of ESb metastases in immunocompetent DBA/2 mice. Either treatment alone was ineffective. The anti-metastatic effect was specific for the ESb lymphoma as spleen cells from ESb-immunized mice together with IFN-alpha/beta treatment did not inhibit the development of metastases in mice challenged with IFN-alpha/beta-resistant 3C18 FLC. Depletion of CD8+ T cells (but not CD4+ T cells or B lymphocytes) prior to transfer eliminated the protective effect of ESb-immune splenocytes in IFN-alpha/beta-treated mice. As few as 1 x 10(6) ESb-immune spleen cells highly enriched for CD8+ cells increased the survival time of IFN-alpha/beta-treated ESb-challenged DBA/2 mice. The combined therapy of ESb-specific immune cells and IFN-alpha/beta resulted in long-term immunity to this tumor.     

Spiral core made of grain-oriented electrical steel sheet

Spiral cores made of grain-oriented electrical steel sheets (GO) were developed to be used as a high performance motor core. All teeth directions are coincident with the GO rolling directions (easy magnetization axis) in the spiral cores. The GO spiral cores have excellent properties because the GO has very low iron loss and very high permeability in the rolling direction. In the GO spiral cores, the iron losses decrease to a quarter and the inductions are 0.2 T higher at 800 A/m as compared with conventional spiral cores made usually of SPCC. Because the thickness of conventional spiral cores generally varies, applications are limited to automobile alternator cores. The thickness of GO spiral cores changes little during a spiral deformation because the core sheets are deformed transversely to the rolling direction of GO, that is, <110>{011}; the <110>{011} deformation of Fe does not create sheet thickness. As the stiffness and packing factor of a GO spiral core are high in the order of no thickness change, GO spiral cores have high performance for motor cores. © 1997 Scripta Technica, Inc. Electr Eng Jpn, 118 (3): 58–66, 1997     

Pt nanoparticles sputter-deposited on TiO2/MWCNT composites prepared by atomic layer deposition: Improved electrocatalytic activity towards the oxygen reduction reaction and durability in acid media

Acid-treated multi-walled carbon nanotubes (MWCNTs) were decorated with TiO₂ using the atomic layer deposition (ALD) technique followed by uniform distribution of platinum nanoparticles (PtNPs) through magnetron sputtering. Surface analyses were performed by scanning electron microscopy (SEM), scanning transmission electron microscopy (STEM) and X-ray photoelectron spectroscopy (XPS). Electrochemical decontamination and characterization of the Pt-TiO₂/MWCNT electrodes were carried out by CO stripping followed by cyclic voltammetry in acid media. The oxygen reduction reaction (ORR) was studied in O₂-saturated 0.05 M H₂SO₄ solution using the rotating disk electrode (RDE) method. Durability of the prepared catalysts was examined by repetitive potential cycling. Electrochemical data obtained was analyzed and compared to that of the commercial Pt/C catalyst. It was revealed that the Pt-TiO₂/MWCNT catalysts possess higher ORR activity and better durability as compared to that of the commercial Pt/C.     

Electrochemical reduction of oxygen on thin-film Pt electrodes in acid solutions

The electrochemical reduction of oxygen on thin-film platinum electrodes in 0.1 M HClO₄ and 0.05 M H₂SO₄ solutions has been investigated using the rotating disk electrode (RDE) method. Thin films of Pt (0.25-20 nm thick) were prepared by vacuum evaporation onto glassy carbon substrate. The surface morphology of Pt films was examined by transmission electron microscopy (TEM). The specific activity of O₂ reduction was higher in HClO₄ and decreased with decreasing film thickness. In H₂SO₄, the specific activity was lower and appeared to be independent of the Pt loading. The values of Tafel slopes close to −120 mV dec⁻¹ in high current density range and −60 mV dec⁻¹ in low current density range were obtained for all electrodes in both solutions, indicating that the mechanism of O₂ reduction is the same for thin-film electrodes as for bulk Pt. The number of electrons transferred per O₂ molecule was close to four for all thin Pt films studied.     

A Second Life for MAP,a Model Amphipathic Peptide

Cell-penetrating peptides (CPP) have been shown to be efficient in the transport of cargoes into the cells, namely siRNA and DNA, proteins and peptides, and in some cases, small therapeutics. These peptides have emerged as a solution to increase drug concentrations in different tissues and various cell types, therefore having a relevant therapeutic relevance which led to clinical trials. One of them, MAP, is a model amphipathic peptide with an α-helical conformation and both hydrophilic and hydrophobic residues in opposite sides of the helix. It is composed of a mixture of alanines, leucines, and lysines (KLALKLALKALKAALKLA). The CPP MAP has the ability to translocate oligonucleotides, peptides and small proteins. However, taking advantage of its unique properties, in recent years innovative concepts were developed, such as in silico studies of modelling with receptors, coupling and repurposing drugs in the central nervous system and oncology, or involving the construction of dual-drug delivery systems using nanoparticles. In addition to designs of MAP-linked vehicles and strategies to achieve highly effective yet less toxic chemotherapy, this review will be focused on unique molecular structure and how it determines its cellular activity, and also intends to address the most recent and frankly motivating issues for the future.     

Transition metal phthalocyanine-modified shungite-based cathode catalysts for alkaline membrane fuel cell

The alkaline anion exchange membrane fuel cell (AEMFC) is one of the green solutions for the growing need for energy conversion technologies. For the first time, we propose a natural shungite based non-precious metal catalyst (NPMC) as an alternative cathode catalyst to Pt-based materials for AEMFCs application. The Co and Fe phthalocyanine (Pc)-modified shungite materials were prepared via pyrolysis and used for oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) studies. The most promising ORR performance was observed in alkaline media for FePc-modified and acid-leached shungite-based NPMC material. The catalysts were also evaluated as cathode materials in a single cell AEMFC and peak power densities of 232 and 234 mW cm^?2 at 60 °C using H₂ and O₂ gases at 100% RH were observed for CoPc- and FePc-modified acid-treated materials, respectively.