365 research outputs found
Capsule endoscopy interpretation: the role of physician extenders
Background and aims: capsule endoscopy (CE) allows for a
new era in small-bowel examination. Nevertheless, physiciansâ
time for CE-interpretation remains longer than desirable. Alternative
strategies to physicians have not been widely investigated.
The aim of this study was to evaluate the accuracy of physician
extenders in CE-interpretation.
Material and methods: one CE-experienced gastroenterologist
and two physician extenders reviewed independently 20 CEprocedures.
Each reader was blinded to the findings of their colleagues.
A consensus formed by the readers and a second
CE-experienced gastroenterologist was used as gold standard.
Number, type and location of images selected, character of CEexams
and their relationship with indications were recorded. Gastric
emptying time (GEt), small-bowel transit time (SBTt) and time
spent by readers were also noted.
Results: sensitivity and specificity for âoverallâ lesions was 79
and 99% for the gastroenterologist; 86 and 43% for the nurse;
and 80 and 57% for the resident. All 34 âmajorâ lesions considered
by consensus were found by the readers. Agreement between
consensus and readers for images classification and procedures
interpretation was good to excellent (Îș from 0.55 to 1). No
significant differences were found in the GEt and SBTt obtained
by consensus and readers. The gastroenterologist was faster than
physician extenders (mean time spent was 51.9 ± 13.5 minutes
versus 62.2 ± 19 and 60.9 ± 17.1 for nurse and resident, respectively;
p < 0.05).
Conclusions: physician extenders could be the perfect complement
to gastroenterologists for CE-interpretation but gastroenterologists
should supervise their findings. Future cost-efficacy
analyses are required to assess the benefits of this alternative
High One-Dimensional Charge Mobility in Semiconducting Columnar Mesophases of Isocyano-Triphenylene Metal Complexes
ProducciĂłn CientĂficaThis paper reports the synthesis, liquid crystal behavior, and charge-transport properties in the mesophase of isocyano-triphenylene gold, copper, palladium, and platinum complexes [MX(CNR)] (CNR = 2-(6-(4-isocyanophenoxy)hexyloxy)-3,6,7,10,11-pentakisdodecyloxytriphenylene; M = Au, X = Cl, C6F5, C6F4OC10H21, CN; M = Cu, X = Cl), [(ÎŒ-4,4âČ-C6F4C6F4){Au(CNR)}2], [(ÎŒ-Cl2){Cu(CNR)2}2], and [MX2(CNR)2] (M = Pd, Pt; X = Cl, Br, I, and M = Pt, X = CN). The thermal and electronic properties of these materials are modulated by the metal fragment. The complexes that display columnar mesomorphism are those that support more than one triphenylene per molecule or those that produce a similar effect by dipoleâdipole interactions between the metal groups. These circumstances improve the balance of favorable enthalpic interactions versus unfavorable entropic contributions into a columnar stacking. Hybrid inorganic/organic dual columnar mesophases with high SCLC hole mobility along the columnar stacking, above 1 cm2 Vâ1 sâ1, have been found. It is worth noting that the dicyanoplatinum complex displays mesophase phosphorescence based on Pt···Pt interactions.Ministerio de Ciencia e InnovaciĂłn (Proyect CTQ2014-52796-P
A lightweight tile structure integrating photovoltaic conversion and RF power transfer for space solar power applications
We demonstrate the development of a prototype lightweight (1.5 kg/m^3) tile structure capable of photovoltaic solar power capture, conversion to radio frequency power, and transmission through antennas. This modular tile can be repeated over an arbitrary area to forma large aperture which could be placed in orbit to collect sunlight and transmit electricity to any location. Prototype design is described and validated through finite element analysis, and high-precision ultra-light component manufacture and robust assembly are described
In-situ and Ex-situ characterization of III-V semiconductor materials and solar cells upon 10 MEV proton irradiation
In this work we present the results and analysis of a 10 MeV proton irradiation experiment performed on III-V semiconductor materials and solar cells. A set of representative devices including lattice-matched InGaP/GaInAs/Ge triple junction solar cells and single junction GaAs and InGaP component solar cells and a Ge diode were irradiated for different doses. The devices were studied in-situ before and after each exposure at dark and 1 sun AM0 illumination conditions, using a solar simulator connected to the irradiation chamber through a borosilicate glass window. Ex-situ characterization techniques included dark and 1 sun AM0 illumination I-V measurements. Furthermore, numerical simulation of the devices using D-AMPS-1D code together with calculations based on the TRIM software were performed in order to gain physical insight on the experimental results. The experiment also included the proton irradiation of an unprocessed Ge solar cell structure as well as the irradiation of a bare Ge(100) substrate. Ex-situ material characterization, after radioactive deactivation of the samples, includes Raman spectroscopy and spectral reflectivity
A lightweight tile structure integrating photovoltaic conversion and RF power transfer for space solar power applications
We demonstrate the development of a prototype lightweight (1.5 kg/m^3) tile structure capable of photovoltaic solar power capture, conversion to radio frequency power, and transmission through antennas. This modular tile can be repeated over an arbitrary area to forma large aperture which could be placed in orbit to collect sunlight and transmit electricity to any location. Prototype design is described and validated through finite element analysis, and high-precision ultra-light component manufacture and robust assembly are described
Versatile Coordination of Cyclopentadienyl-Arene Ligands and Its Role in Titanium-Catalyzed Ethylene Trimerization
Cationic titanium(IV) complexes with ansa-(η5-cyclopentadienyl,η6-arene) ligands were synthesized and characterized by X-ray crystallography. The strength of the metal-arene interaction in these systems was studied by variable-temperature NMR spectroscopy. Complexes with a C1 bridge between the cyclopentadienyl and arene moieties feature hemilabile coordination behavior of the ligand and consequently are active ethylene trimerization catalysts. Reaction of the titanium(IV) dimethyl cations with CO results in conversion to the analogous cationic titanium(II) dicarbonyl species. Metal-to-ligand backdonation in these formally low-valent complexes gives rise to a strongly bonded, partially reduced arene moiety. In contrast to the η6-arene coordination mode observed for titanium, the more electron-rich vanadium(V) cations [cyclopentadienyl-arene]V(NiPr2)(NC6H4-4-Me)+ feature η1-arene binding, as determined by a crystallographic study. The three different metal-arene coordination modes that we experimentally observed model intermediates in the cycle for titanium-catalyzed ethylene trimerization. The nature of the metal-arene interaction in these systems was studied by DFT calculations.
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