1,721,084 research outputs found
H2S gas interaction with Pt(II)-containing polymetallaynes of selected chain length: An XPS and EXAFS study
No full textThe interaction between gaseous H2S and the surface of several metal-containing oligomers, investigated by emission and absorption spectroscopies, is presented and discussed. The polymetallayne trans-{Cl-[Pt(PBu3)(2)(C C-C6H4-C6H4-C C)](9)Pt(PBu3)(2)Cl} and related model molecules, i.e. the binuclear transition metal dialkynyl bridged Pt(II) square planar complex trans,trans-[ClPt(PBu3)(2)(C C-C6H4-C6H4 Pt(PBu3)(2)CI], the tetranuclear linear oligomer trans-[Cl-[Pt(PBu3)(2)(C C-C6H4-C6H4-C C)](3)Pt(PBu3)(2)Cl}, the tetranuclear cyclic oligomer cis- [Pt(PBu3)(2)(C C - C6H4-C6H4 -C C)](4), were exposed to hydrogen sulfide and then investigated by X-ray photoelectron (XPS) and X-ray absorption (XAS) spectroscopies, in order to shed light on the gas/polymer interaction associated to the sensing properties of these materials. XPS measurements evidenced the presence of S in the polymetallayne samples exposed to H2S, and the measured S2p binding energy values correlate with H2S adsorbed by means of sulfur atoms chemically bonded to metal atoms, owing to the formation of sulfur-containing adducts. XAS data analysis suggested a squarepyramidal geometry around the transition metal with H2S in the apical position for the pentacoordinated platinum units
Nanostructured polymetallaynes of controlled length: Synthesis and characterization of oligomers and polymers from 1,1 '-bis-(ethynyl)4,4 '-biphenyl bridging Pt(II) or Pd(II) centers
No full textThe reactivity of square planar palladium(II) and platinum(II) complexes in trans or cis configuration, namely trans or cis- [dichlorobis(tributylphosphine)platinum(II)] and trans-[dichlorobis(tributylphosphine)palladium(II)I with 1,1'-bis(ethynyl) 4,4'-biphenyl, DEBP, leading to pi-conjugated organometallic oligomeric and polymeric metallaynes, was investigated by a systematic variation of the reaction conditions. The formation of polymers and oligomers with defined chain length [-M(PBu3)(2) (C C-C6H4-C6H4-C C-)](n) (n = 3-10 for the oligomers, n = 20-50 for the polymers) depends on the configuration of the precursor Pt(II) and Pd(II) complexes, the presence/absence of the catalyst CuI, and the reaction time. A series of model reactions monitored by XPS, GPC, and NMR P-31 spectroscopy showed the route to modulate the chain growth. As expected, the nature of the transition metal (Pt or Pd) and the molecular weight of the polymers markedly influence the photophysical characteristics of the polymetallaynes, such as optical absorption and emission behavior. Polymetallaynes with nanostructured morphology could be obtained by a simple casting procedure of polymer solutions
Acute occlusion of descending thoracic aorta
Full text linkAcute aortic occlusion is a rare but potentially devastating clinical event, which requires a prompt diagnosis and emergency treatment. Only 5 cases of native thoracic aorta acute occlusion have so far been reported with different pathologic causes. The clinical features depend on the level of occlusion. Sometimes the diagnosis could be misinterpreted as a stroke or other diseases of the central nervous system. This could lead to a delay in the diagnosis and revascularization procedure, followed by a morbidity or mortality increase. Open surgery has been considered the first-line approach. This study is of a female patient suffering from acute descending thoracic aorta occlusion undergoing, for the first time to our knowledge, endovascular surgical treatment
Endovascular Management Of Acute Carotid-Artery Dissection With Waxing and Waning Neurological Deficit: A Case Report.
No full textPURPOSE: To evaluate the feasibility and efficacy of emergent carotid stenting for an acute internal carotid artery (ICA) dissection.
CASE REPORT: A 51-year-old man was admitted to our emergency department's stroke unit 1 hour after the onset of left hemiparesis. Computed tomographic and transcranial Doppler scans showed no pathological findings, but the color Doppler study detected a double lumen in the right carotid bifurcation extending to the proximal ICA. Within the first 2 hours after admission, the patient's neurological status began to fluctuate; the NIH Stroke Scale (NIHSS) and Rankin scores evaluated each hour after admission ranged from 0 to 12 and from 0 to 3, respectively. Emergency carotid angiography confirmed the dissection of the bulb and proximal right ICA, which prompted implantation of 2 Wallstents from the internal to common carotid artery. Forty-eight hours later, the patient was almost totally asymptomatic with an NIHSS score of 1 and a Rankin score of 0; he was discharged on postoperative day 3. At 3 months, the patient was free of neurological symptoms and the stented carotid artery was patent.
CONCLUSIONS: In patients with fluctuating neurological signs and symptoms consistent with carotid artery dissection that are refractory to medical therapy, a stent can be placed to prevent permanent neurological deficits provided that the anatomical conditions are suitabl
Development of an error model for a factory-calibrated continuous glucose monitoring sensor with 10-day lifetime
Full text linkFactory-calibrated continuous glucose monitoring (FC-CGM) sensors are new devices used in type 1 diabetes (T1D) therapy to measure the glucose concentration almost continuously for 10–14 days without requiring any in vivo calibration. Understanding and modelling CGM errors is important when designing new tools for T1D therapy. Available literature CGM error models are not suitable to describe the FC-CGM sensor error, since their domain of validity is limited to 12-h time windows, i.e., the time between two consecutive in vivo calibrations. The aim of this paper is to develop a model of the error of FC-CGM sensors. The dataset used contains 79 FC-CGM traces collected by the Dexcom G6 sensor. The model is designed to dissect the error into its three main components: effect of plasma-interstitium kinetics, calibration error, and random measurement noise. The main novelties are the model extension to cover the entire sensor lifetime and the use of a new single-step identification procedure. The final error model, which combines a first-order linear dynamic model to describe plasma-interstitium kinetics, a second-order polynomial model to describe calibration error, and an autoregressive model to describe measurement noise, proved to be suitable to describe FC-CGM sensor errors, in particular improving the estimation of the physiological time-delay
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Full text linkWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Structural characterization of 3d metal adsorbed AgNPs
No full textSilver nanoparticles AgNPs having small (6–8 nm) diameter, were synthesized in water in solutions and left interacting with diluted 3d metals (Co2+ or Ni2+ ions) solution (1–5 ppm range). The interactions between AgNPs and the metallic ions modify the optical response of the nanoparticles demonstrating their ability to capture metallic ions from water and making them valuable as metal contamination sensor. Here the coordination chemistry of Co and Ni adsorbed onto AgNPs is probed combining X-ray absorption spectroscopy (XAS) and X-ray photoelectron spectroscopy (XPS)
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