Electrocatalytic Oxidation of Nitric Oxide at Carbon Paste Electrode Modified with Chromium (III) Oxide

Chromium (III) oxide was used as a bulk mediator in carbon paste electrodes to improve the better performance of the carbon electrodes for the detection of nitric oxide in comparison with unmodified electrodes. The reaction mechanism of the electrocatalytic oxidation of NO at the modified electrode was studied using cyclic voltammetry and differential pulse voltammetry. The chemical sensor could be operated under physiological conditions (pH 7.5, 0.1 M phosphate buffer), with an operating potential of 750 mV (vs. Ag/AgCl), in hydrodynamic amperometry. The amperometric response of the sensor showed good linearity up to 200 mmol/L with a detection limit (3σ) of 0.69 mmol/L. The effect of the interferent nitrite was not fatal and could be eliminated by the use of the standard addition method. The new chemical sensor seems also promising to detect NO in car exhaust fumes

Enriching of Magnesite Ore Containing Dolomite

Glavne primjese magnezitne rude rudnika "Strezovce" su minerali silicija i kalcija koji nepovoljno utječu na vatrostalnost proizvoda na osnovi magnezijevog oksida. Stoga se proizvodnja i prerada magnezitne rude provodi s ciljem smanjenja njihovog masenog udjela. Za uklanjanje primjesa minerala silicija postoje razrađeni tehnološki postupci, dok je uklanjanje primjesa minerala kalcija samo na osnovu mehaničkih separacijskih operacija nezadovoljavajuće. U ovom su radu prikazani rezultati istraživanja utjecaja temperature i vremena žarenja magnezitne rude te načina naknadne hidratacije na oplemenjivanje sirovine u taložnom separatoru s gustom suspenzijom. Istraživanja su pokazala da je optimalna temperatura žarenja rude od 600 - 700 °C tijekom 4 i 6 h, a nakon hidratacije i taložne separacije ρ = 2,20 g cm-3 dobiva se sirovina sa smanjenim udjelom kalcija i silicija. Procesom hidratacije u dinamičkim uvjetima zbog usitnjavanja materijala nastaju velike količine sitne klase, manje od d = 0,5 mm, koja nepovoljno utječe na udjel kvalitetnog proizvoda. Tijekom hidratacije potapanjem žarenog materijala to se ne događa. U radu je ustanovljen i povoljan utjecaj produljene termičke obrade na iskorištenje proizvoda te optimalna gustoća guste suspenzije za dobivanje kvalitetnog proizvoda.Minor mineral phases containing calcium and silica in magnesite ore are the main cause of detrimental properties of magnesia refractory materials prepared thereof. All stages of the production process aim to remove such unwanted mineral phases. While the removal of silica minerals is well documented, it is not so for the calcium containing minerals, especially when it is not possible to do so by mechanical separation processes only. In this work, the influence of duration and temperature of heat treatment and subsequent hydration of magnesia has been studied. The final product obtained is a light component from the settling separation utilizing dense water suspension of ferrosilica. The optimal process conditions were: 4 to 6 h soaking at temperature between 600 and 700 °C with subsequent hydration of partially calcined product by immersion in water and settling separation at heavy fluid density ρ= 2.20 g cm–3. Furthermore, a positive influence of prolonged heat treatment on product quality as well as the optimal density of ferrosilica suspension has been obtained

Articulation entropy: An unsupervised measure of articulatory precision

Articulatory precision is a critical factor that influences speaker intelligibility. In this paper, we propose a new measure we call ‘articulation entropy’ that serves as a proxy for the number of distinct phonemes a person produces when he or she speaks. The method is based on the observation that the ability of a speaker to achieve an articulatory target, and hence clearly produce distinct phonemes, is related to the variation of the distribution of speech features that capture articulation - the larger the variation, the larger the number of distinct phonemes produced. In contrast to previous work, the proposed method is completely unsupervised, does not require phonetic segmentation or formant estimation, and can be estimated directly from continuous speech. We evaluate the performance of this measure with several experiments on two data sets: a database of English speakers with various neurological disorders and a database of Mandarin speakers with Parkinson’s disease. The results reveal that our measure correlates with subjective evaluation of articulatory precision and reveals differences between healthy individuals and individuals with neurological impairment

ADMM in Krylov Subspace and Its Application to Total Variation Restoration of Spatially Variant Blur

In this paper we propose an efficient method for a convex optimization problem which involves a large nonsymmetric and non-Toeplitz matrix. The proposed method is an instantiation of the alternating direction method of multipliers applied in Krylov subspace. Our method offers significant advantages in computational speed for the convex optimization problems involved with general matrices of large size. We apply the proposed method to the restoration of spatially variant blur. The matrix representing spatially variant blur is not block circulant with circulant blocks (BCCB). Efficient implementation based on diagonalization of BCCB matrices by the discrete Fourier transform is not applicable for spatially variant blur. Since the proposed method can efficiently work with general matrices, the restoration of spatially variant blur is a good application of our method. Experimental results for total variation restoration of spatially variant blur show that the proposed method provides meaningful solutions in a short time.clos

Acoustic and perceptual speech characteristics of native Mandarin speakers with Parkinson Disease

This study examines acoustic features of speech production in speakers of Mandarin with Parkinson's disease (PD) and relates them to intelligibility outcomes. Data from 11 participants with PD and 7 controls are compared on several acoustic measures. In speakers with PD, the strength of association between these measures and intelligibility is investigated. Speakers with PD exhibited significant differences in fundamental frequency, pitch variation, vowel space, and rate relative to controls. However, in contrast to the English studies, speech rate was consistently slow and most strongly correlated with intelligibility. Thus, acoustic cues that strongly influence intelligibility in PD may vary cross-linguistically

Effect of oxytocin infusion on luteal blood flow and progesterone secretion in dairy cattle

The objective of this study was to investigate the effects of oxytocin infusion on corpus luteum (CL) function during early to mid-diestrus by measuring luteal size (LS) and luteal blood flow (LBF) along with plasma levels of progesterone (P4) and prostaglandin metabolites (13,14-dihydro-15-keto-prostaglandin F2α, PGFM). On day (D) 7 of the estrus cycle (D1 = ovulation), seven cows received 100 IU of oxytocin (OXY) or placebo (PL) following a Latin square design. LS and LBF increased in both groups over time and no differences were observed between the groups. PGFM did not differ either within the groups over time or between the groups at any time point. P4 of the OXY group was higher compared to that of the the PL group 360 min after the infusion (p = 0.01) and tended to be higher at the time points 450 min, 48 h, and 72 h (all p = 0.08). Results from this study support the hypothesis that OXY is not directly involved in the mechanism(s) governing blood flow of the CL and has no remarkable effects either on luteal size or P4 and PGFM plasma levels. Further investigation is needed to elucidate the role of OXY in CL blood flow during early and late luteal phases