Improved electrode gives high-quality biological recordings

To obtain high quality waveforms from a subject engaged in physical activity, an improved electrode assembly has been devised. This consists of a cup containing an electrically conductive paste and a silver electrode. The paste maintains contact between the skin and the plate

Electrode for biological recording

Electrochemically reversible silver-silver chloride electrode for detecting bioelectric potential differences generated by human muscles and organ

Assessment of quality indicators among nurse practitioners performing upper endoscopy.

Background and study aims Limited international data have shown that non-physicians can safely perform upper endoscopy, but no such study has been performed in the United States. Our aim was to assess the quality of outpatient upper endoscopies performed by nurse practitioners (NPs).Patients and methods Retrospective chart review of upper endoscopies performed by 3 NPs between 2010 and 2013 was performed. Comparisons among all NPs performing upper endoscopy and assessment of individual NP performance over time with respect to quality indicators were performed.Results Three NPs performed 333 upper endoscopies (distribution of 166, 44, and 123, respectively). Of the cases, 98.2 %s were successfully completed to the second portion of the duodenum. In most cases, photo-documentation of required anatomical landmarks was performed: GE junction (84.2 %), GE junction in retroflexed view (84.2 %), antrum (82.1 %) and duodenum (80.9 %). Photo-documentation improved with increasing experience. NPs appropriately performed biopsies for specific medical conditions: 10/11 (90.9 %) gastric ulcers were biopsied and 63/66 (95.5) of patients with iron deficiency had duodenal biopsies performed for celiac disease. A physician endoscopist was required during the procedure 22.5 % of the time. Important parameters such as documenting informed consent (100 %) and documenting a discharge plan (99.4 %) in the procedure reports were overwhelming present. There was a single adverse event during the study period.Conclusion In the first US study of NPs performing upper endoscopy, they were able to perform high-quality and safe upper endoscopies. These findings support incorporation of non-physicians alongside physicians to help meet the growing demand for endoscopic services across the United States

Radioisotope thermal photovoltaic application of the GaSb solar cell

An examination of a RTVP (radioisotopic thermophotovoltaic) conceptual design has shown a high potential for power densities well above those achievable with radioisotopic thermoelectric generator (RTG) systems. An efficiency of 14.4 percent and system specific power of 9.25 watts/kg were predicted for a system with sixteen GPHS (general purpose heat source) sources operating at 1100 C. The models also showed a 500 watt system power by the strontium-90 isotope at 1200 C at an efficiency of 17.0 percent and a system specific power of 11.8 watts/kg. The key to this level of performance is a high-quality photovoltaic cell with narrow bandgap and a reflective rear contact. Recent work at Boeing on GaSb cells and transparent back GaAs cells indicate that such a cell is well within reach

Terminal ruthenium carbido complexes as σ-donor ligands

The terminal carbido ligand of (Pcy_3)_2(Cl)_2RuC coordinates to other metal centers in a σ-donor fashion, as in (Pcy_3)_2(Cl)_2Ru≡C–Pd(Cl)_2(Sme_2) and (Pcy_3)_2(Cl)_2Ru≡C–Mo(CO)_5

Amine, Amido, and Imido Complexes of Tantalum Supported by a Pyridine-Linked Bis(phenolate) Pincer Ligand: Ta−N π-Bonding Influences Pincer Ligand Geometry

A series of tantalum imido and amido complexes supported by a pyridine-linked bis(phenolate) ligand has been synthesized. Characterization of these complexes via X-ray crystallography reveals both C_s and C_2 binding modes of the bis(phenolate)pyridine ligand, with complexes containing two or fewer strong π-donor interactions from ancillary ligands giving C_s symmetry, whereas three strong π-donor interactions (e.g., three amido ligands or one amido ligand and one imido ligand) give C_2-symmetric binding of the bis(phenolate)pyridine ligand. DFT calculations and molecular orbital analyses of the complexes have revealed that the preference for C_s-symmetric ligand binding is a result of tantalum−phenolate π-bonding, whereas in cases where tantalum−phenolate π-bonding is overridden by stronger Ta−N π-bonding, C_2-symmetric ligand binding is preferred, likely because conformationally this is the lowest-energy arrangement. This electronically driven change in geometry indicates that, unlike analogous metallocene systems, the bis(phenolate)pyridine pincer ligand is not a strong enough π-donor to exert dominant control over the electronic and geometric properties of the complex

Cationic Alkylaluminum-Complexed Zirconocene Hydrides: NMR-Spectroscopic Identification, Crystallographic Structure Determination, and Interconversion with Other Zirconocene Cations

The ansa-zirconocene complex rac-Me_2Si(1-indenyl)_2ZrCl_2 ((SBI)ZrCl_2) reacts with diisobutylaluminum hydride and trityl tetrakis(perfluorophenyl)borate in hydrocarbon solutions to give the cation [(SBI)Zr(μ-H)_3(Al^iBu_2)_2]^+, the identity of which is derived from NMR data and supported by a crystallographic structure determination. Analogous reactions proceed with many other zirconocene dichloride complexes. [(SBI)Zr(μ-H)_3(Al^iBu2)_2]^+ reacts reversibly with ClAl^iBu_2 to give the dichloro-bridged cation [(SBI)Zr(μ-Cl)_2Al^iBu_2]^+. Reaction with AlMe_3 first leads to mixed-alkyl species [(SBI)Zr(μ-H)_3(AlMe_x^iBu_(2−x))_2^]+ by exchange of alkyl groups between aluminum centers. At higher AlMe_3/Zr ratios, [(SBI)Zr(μ-Me)_2AlMe_2]^+, a constituent of methylalumoxane-activated catalyst systems, is formed in an equilibrium, in which the hydride cation [(SBI)Zr(μ-H)_3(AlR_2)_2]^+ strongly predominates at comparable HAl^iBu_2 and AlMe_3 concentrations, thus implicating the presence of this hydride cation in olefin polymerization catalyst systems

Synthesis and C−C Coupling Reactivity of a Dinuclear Ni^I−Ni^I Complex Supported by a Terphenyl Diphosphine

Mono- and bimetallic complexes of nickel supported by a terphenyl diphosphine have been synthesized. The reported complexes show diverse metal−arene interactions in the solid state. Reactions of an o,o′-biphenyldiyl dinickel complex with CO and dichloroalkanes lead to fluorene derivatives, indicating the formation of carbon−carbon bonds at a bimetallic moiety

A homoleptic phosphine adduct of Tl(I)

A homoleptic phosphine adduct of thallium(I) supported by a tris(phosphino)borate ligand has been isolated and structurally characterized