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Spectroscopic insights into the electrochemical mechanism of rechargeable calcium/sulfur batteries
Giuliana Aquilanti, Jan Bitenc, Romain Berthelot, Antonio Scafuri, Alen Vižintin, Klemen Pirnat, Lorenzo Stievano, Robert Dominko, Iztok Arčon, Rémi Dedryvère, Dominique Foix, 13, izvirni znanstveni članek

Opis: Calcium batteries represent a promising alternative to lithium metal systems. The combination of the low redox potential and low cost and the energy-dense calcium anode (2073 mAh/cm3, similar to 2044 mAh/cm3 for Li) with appropriate low-cost cathode materials such as sulfur could produce a game-changing technology in several fields of applications. In this work, we present the reversible activity of a proof-of-concept Ca/S battery at room temperature, characterized by a surprising medium-term cycling stability with low polarization, promoted by the use of a simple positive electrode made of sulfur supported on an activated carbon cloth scaffold, and a state-of-the-art fluorinated alkoxyborate-based electrolyte. Insights into the electrochemical mechanism governing the chemistry of the Ca/S system were obtained for the first time by combining X-ray photoelectron spectroscopy and X-ray absorption spectroscopy. The mechanism implies the formation of different types of soluble polysulfide species during both charge and discharge at room temperature, and the formation of solid CaS at the end of discharge. The reversible electrochemical activity is proven by the reformation of elemental sulfur at the end of the following charge. These promising results open the way to the comprehension of emerging Ca/S systems, which may represent a valid alternative to Mg/S and Li/S batteries.
Najdeno v: ključnih besedah
Ključne besede: Calcium/Sulfur Batteries EXAFS, XANES
Objavljeno: 17.10.2020; Ogledov: 214; Prenosov: 0
.pdf Polno besedilo (3,74 MB)

Sebastijan Rep, 2016, magistrsko delo

Opis: Parathyroid scintigraphy is based on the different accumulation and distribution of radiopharmaceutical 99mTc-MIBI (MIBI) in parathyroid and adjacent tissues. Different scintigraphic techniques can be used: subtraction scintigraphy is a combination of MIBI and 99mTc-pertehnetate (pertehnetate) scintigraphy; SPECT can be performed after intravenous injection of MIBI or in the combination with low-dose computerized tomography (SPECT/CT) which allows precise anatomical localization of enlarged parathyroid glands (EPG). The objectives of our study were: to assess diagnostic performance of preoperative localization of EPG (adenomas and hyperplasia) of the early, delayed and combined SPECT/CT and of subtraction scintigraphy in patients with biochemically proven primary hyperparathyroidism (PHP); to determine whether size of EPG, serum parathyroid hormone (PTH), calcium (Ca) and phosphate (P) correlate with successful localization; to assess radiation exposure of patients with early and late SPECT/CT and subtraction scintigraphy The study included 41 patients in whom early, delay SPECT/CT and subtraction scintigraphy were performed. For all scintigraphic methods sensitivity, specificity, positive predictive value, negative predictive value and accuracy were calculated. Receiver Operating Characteristic analysis was used to express relationship between scintigraphy results and size of the EPG and serum Ca, P and PTH levels. ImPACT CT Patient Dosimetry Calculator and weighting factors for radiopharmaceuticals (MIBI and pertechnetate) were used for calculating patient expose dose. Sensitivity and specificity were 51.1% and 98.3 for subtraction scintigraphy, 65.1% and 97.5% for early SPECT/CT and 65.1% and 95.5% for delay SPECT/CT. In combined early and delay SPECT/CT sensitivity and specificity were 74.4% and 95.1%.Only size of the EPG correlated with successful localization in our study (AUC of 0.791-0.810). The highest average ED per patient had subtraction scintigraphy (7.37±0.40 mSv), which was statistically significant higher in comparison to combined early and delayed SPECT/CT (6.81±0.44 mSv). The most sensitive and most accurate method of preoperative localization of EPG in patients with PHP is combined early and delayed SPECT/CT. Only size of the EPG correlates with successful localization. The highest radiation exposure is after subtraction scintigraphy.
Najdeno v: ključnih besedah
Povzetek najdenega: ...size of EPG, serum parathyroid hormone (PTH), calcium (Ca) and phosphate (P) correlate with successful...
Ključne besede: Enlarged parathyroid glands, early SPECT/CT, delayed SPECT/CT, combined SPECT/CT, subtraction scintigraphy, 99mTc-MIBI, 99mTc-pertechnetate, effective dose, serum parathyroid hormone, calcium, phosphate
Objavljeno: 03.10.2016; Ogledov: 3477; Prenosov: 173
.pdf Polno besedilo (1,03 MB)

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