Differential Capacity of Bromide Anions Adsorption onto Ag(100) in the Absence, and onto Ag(poly) in the Presence of NaClO4

In this work, the adsorption of bromide anions onto Ag(100) and Ag(poly) in the absence and presence of NaClO4 was investigated. The cyclic voltammetry, EIS and Cdiff vs. E measurement results were analyzed. For the determination of the adsorption parameters, the equivalent circuit containing constant phase element (CPE) instead of the double layer capacity (Cdl) and new equations for the analysis of the anion adsorption, based on a different definition of the CPE, have been developed and used. It was shown that the proposed equivalent circuit and corresponding equations for the differential capacity (Cdiff) as a function of frequency (ω) can successfully be applied in the investigated systems. Excellent agreement between the cyclic voltammograms (CVs) and the Cdiff vs. E curves recorded at frequencies lower than 10 Hz has been detected. The homogeneity of the charge distribution over the real single crystal surfaces, as well as other parameters of the adsorption process were found to change with the potential. In the presence of the supporting (“non-adsorbing”) electrolyte (0.1 M NaClO4) diffusion-like phenomenon was detected and ascribed to the slow step in exchanging anions adsorbed in the inner Helmholtz plane

Pragmaticalization of modal verbs could and would in the Еnglish language from 1800 until present day ; Прагматикализация модальных глаголов could и would в английском языке с 1800. года до настоящего времени

Још увек се мало зна о развоју прагматичких образаца употребе језика. Стога се ова докторска дисертација бави процесом прагматикализације модалних глагола could и would, њеним односом са другим процесима језичке промене, као и њеним исходима: прагматичким маркерима и оградама. Главни циљ дисертације је да се спроведе квантитативно и квалитативно, на корпусу засновано, истраживање семантичких и прагматичких карактеристика модалних глагола could и would, као и прагматичких маркера и ограда, који су проистекли из ових модалних глагола. Специфични циљеви рада обухватају формулисање стаза промене, упоређивање развоја could и would, тестирање хипотезе (интер)субјективности, проверу тврдње да ли учесталост основних модала опада, као и покушај оговора на питање да ли прагматички маркери кодирају неки облик модалности ...There is still little knowledge on the development of the pragmatic patterns of language use. Therefore, this doctoral dissertation ia an attempt to deal with the process of pragmaticalization of the modal verbs could and would, its relation to the other processes of language change, as well as its outcomes: pragmatic markers and hedges. The main aim of the dissertation is to carry out quantitative and qualitative, corpus-based, research of semantic and pragmatic characteristics of the modal verbs could and would, as well as pragmatic markers and hedges, derived from these modal verbs. The specific aims of the work include the formulation of the paths of change, the comparison of the development of could and would, testing of the (inter)subjectivity hypothesis, the verification of the claim that the frequency of the basic modal verbs decreases at the beginning of 21st century, as well as the attempt to answer whether the pragmatic markers encode any kind of modality..

Vibration control of resonant vibratory feeders with electromagnetic excitation

Vibracioni dodavači sa elektromagnetnom pobudom, odnosno elektromagnetni vibracioni dodavači (EMVD) su najčešće korišćeni u procesnoj industriji za obezbeđenje gravimetrijskog protoka sitnozrnih i rasutih materijala. Ovi pogoni obezbeđuju laku i jednostavnu kontrolu masenog protoka transportujućih materijala. U poređenju sa ostalim pogonima (pneumatskim, inercionim, centrifugalnim, itd.), oni su jednostavnije i kompaktnije konstrukcije, robusni i pouzdani u radu. Odsustvo habajući mehaničkih delova kao što su reduktori, kišnici, ekscentri i sl., čine EMVD veoma ekonomičnom opremom. Standardni pretvarački izlazni stepeni namenjeni za kontrolu EMVD su bazirani na SCR elementima (tiristorima i trijacima). Njihovo korišćenje podrazumeva korišćenje kontrole faznog ugla (KFU) i stoga konstantnu učestanost vibracija. Na ovaj način kontrolno kolo mora biti sinhronizovano sa mrežnom učestanošću 50(60)Hz. Uz pomoć KFU je jedino moguće ostvariti podešavanje amplitude vibracija, ali ne i njihove učestanosti. Primena prekidačkih tranzistorskih (IGBT ili MOSFET) energetskih pretvarača, omogućava amplitudsku i (ili) frekventnu kontrolu EMVD. Njihovo korišćenje podrazumeva pobudu EMVD nezavisno od mrežne učestanosti. Dodatno, frekventna kontrola dozvoljava rad u oblasti mehaničke rezonance. Rad u ovoj oblasti je veoma efikasan, pošto je moguće obezbediti značajne izlazne pomeraje, veoma malom ulaznom snagom. Optimalan i efikasan rad zahteva praćenje rezonantne učestanosti. U ovom radu su predstavljeni jedno moguće rešenje vibracione kontrole EMVD, kao i odgovarajući simulacioni i eksperimentalni rezultati.The vibratory feeders with electromagnetic excitation called electromagnetic vibratory feeders (EMVF) are commonly used for performing gravimetric flow of granular and particulate materials in processing industry. This drives offer easy and simple control the mass flow of conveying materials. In comparison with other drives (pneumatics, inertial, centrifugal, etc...), these have a more simple construction and they are compact, robust and reliable in operation. The absence of wearing mechanical part, such as gears, cams belts, bearings, eccentrics, etc., makes EMVF, most economical equipment. Standard power electronic output stages intended for control of the EMVF using SCR devices (thyristors and triacs). This implies phase angle control (PAC) and constant frequency of vibration. In this way control circuit must be synchronized to the mains supply frequency 50(60) Hz. PAC can only accomplish tuning amplitude of vibration, but not vibratory frequency. Application of transistor (IGBT or MOSFET) switch mode power converters enables accomplishing the amplitude and (or) frequency control of EMVF. Their use implies the excitation of an EMVF independent of the mains supply frequency. In addition, the frequency control ensures operation in the region of mechanical resonance. This operation is highly efficient, because large output displacement is provided by small input power. An optimal and efficient operation requires tracking of resonant frequency. This paper presents possible solution of the amplitude frequency control of EMVF and corresponding simulation and experimental results

Vibration control of resonant vibratory feeders with electromagnetic excitation

Vibracioni dodavači sa elektromagnetnom pobudom, odnosno elektromagnetni vibracioni dodavači (EMVD) su najčešće korišćeni u procesnoj industriji za obezbeđenje gravimetrijskog protoka sitnozrnih i rasutih materijala. Ovi pogoni obezbeđuju laku i jednostavnu kontrolu masenog protoka transportujućih materijala. U poređenju sa ostalim pogonima (pneumatskim, inercionim, centrifugalnim, itd.), oni su jednostavnije i kompaktnije konstrukcije, robusni i pouzdani u radu. Odsustvo habajući mehaničkih delova kao što su reduktori, kišnici, ekscentri i sl., čine EMVD veoma ekonomičnom opremom. Standardni pretvarački izlazni stepeni namenjeni za kontrolu EMVD su bazirani na SCR elementima (tiristorima i trijacima). Njihovo korišćenje podrazumeva korišćenje kontrole faznog ugla (KFU) i stoga konstantnu učestanost vibracija. Na ovaj način kontrolno kolo mora biti sinhronizovano sa mrežnom učestanošću 50(60)Hz. Uz pomoć KFU je jedino moguće ostvariti podešavanje amplitude vibracija, ali ne i njihove učestanosti. Primena prekidačkih tranzistorskih (IGBT ili MOSFET) energetskih pretvarača, omogućava amplitudsku i (ili) frekventnu kontrolu EMVD. Njihovo korišćenje podrazumeva pobudu EMVD nezavisno od mrežne učestanosti. Dodatno, frekventna kontrola dozvoljava rad u oblasti mehaničke rezonance. Rad u ovoj oblasti je veoma efikasan, pošto je moguće obezbediti značajne izlazne pomeraje, veoma malom ulaznom snagom. Optimalan i efikasan rad zahteva praćenje rezonantne učestanosti. U ovom radu su predstavljeni jedno moguće rešenje vibracione kontrole EMVD, kao i odgovarajući simulacioni i eksperimentalni rezultati.The vibratory feeders with electromagnetic excitation called electromagnetic vibratory feeders (EMVF) are commonly used for performing gravimetric flow of granular and particulate materials in processing industry. This drives offer easy and simple control the mass flow of conveying materials. In comparison with other drives (pneumatics, inertial, centrifugal, etc...), these have a more simple construction and they are compact, robust and reliable in operation. The absence of wearing mechanical part, such as gears, cams belts, bearings, eccentrics, etc., makes EMVF, most economical equipment. Standard power electronic output stages intended for control of the EMVF using SCR devices (thyristors and triacs). This implies phase angle control (PAC) and constant frequency of vibration. In this way control circuit must be synchronized to the mains supply frequency 50(60) Hz. PAC can only accomplish tuning amplitude of vibration, but not vibratory frequency. Application of transistor (IGBT or MOSFET) switch mode power converters enables accomplishing the amplitude and (or) frequency control of EMVF. Their use implies the excitation of an EMVF independent of the mains supply frequency. In addition, the frequency control ensures operation in the region of mechanical resonance. This operation is highly efficient, because large output displacement is provided by small input power. An optimal and efficient operation requires tracking of resonant frequency. This paper presents possible solution of the amplitude frequency control of EMVF and corresponding simulation and experimental results

Electrodeposition and characterization of Fe-Mo alloys as cathodes for hydrogen evolution in the process of chlorate production

Fe-Mo alloys were electrodeposited from a pyrophosphate bath using a single diode rectified AC current. Their composition and morphology were investigated by SEM, optical microscopy and EDS, in order to determine the influence of the deposition conditions on the morphology and composition of these alloys. It was shown that the electrodeposition parameters, such as: chemical bath composition and current density, influenced both the composition of the Fe Mo alloys and the current efficiency for their deposition, while the micro and macro-morphology did not change significantly with changing conditions of alloy electrodeposition. It was found that the electrodeposited Fe Mo alloys possessed a 0.15 V to 0.30 V lower overvoltage than mild steel for hydrogen evolution in ail electrolyte commonly used in commercial chlorate production, depending on the alloy composition, i.e., the conditions of alloy electrodeposition

Electrokinetic Studies in Disperse Systems. VII. Ion Exchange and the Electrokinetic Potential of Precipitates of Silver Iodide

A systematic study of the influence of exchange of ions on the surface of silver iodide precipitates on the elektrokinetic potential (EKP) was undertaken. Examples of the exchange o:f ions of valencies 1 :2, 1 :3, 1 :4, 2 :4 and 3 :4 are given. At higher activity of potential determining ions in solution, at pl= 3, larger changes in the EKP were measured. At the same pl effects of specific adsorption o:f Th4+ were found. The conclusion is drawn, that the exchange of ions at the surface bears no direct, simple relation to the EKP

Ru layers electrodeposited onto highly stable Ti2AlC substrates as cathodes for hydrogen evolution in sulfuric acid solutions

In this work, the hydrogen evolution reaction (HER) was studied on Ru coated Ti2AlC electrodes in 1.0 mol dm(-3) H2SO4 at 25 degrees C. Ti2AlC was found to be a highly stable substrate in sulfuric acid solutions due to the formation of a passivating oxide layer on the surface, which was confirmed by the X-ray photoelectron spectroscopy (XPS) analysis of as-prepared and anodically treated Ti2AlC samples. Ru films were electrodeposited onto Ti2AlC substrates by cycling the potential of Ti2AlC in the solution containing 0.01 mol dm(-3) RuCl3 + 0.1 mol dm(-3) H2SO4 between -0.5 V and 0.4 V vs. a saturated calomel electrode (SCE) at the sweep rate of 20 mV s(-1). Four Ru/Ti2AlC samples were prepared, obtained at 5, 10, 15 and 20 cycles of Ru electrodeposition. Characterization of samples was performed by scanning electron microscopy (SEM) and cyclic voltammetry (CV), while the thickness of the electrodeposited Ru layers was determined by atomic force microscopy (AFM). It was found that the most compact sample with the thickness of about 0.42 mu m was obtained after 5 cycles. Electrochemical impedance spectroscopy (EIS) and steady-state polarization measurements showed that all Ru/Ti2AlC electrodes were exceptionally active for the HER. A Tafel slope of about -60 mV dec(-1) was observed on all polarization curves in the range of high cathodic current densities. Based on formal kinetics analysis, an appropriate mechanism for the HER on Ru/Ti2AlC was suggested.This is the peer-reviewed version of the article: Jovic, B. M., Jović, V. D., Lačnjevac, U., Stevanović, S., Kovac, J., Radovic, M.,& Krstajić, N. V. (2016). Ru layers electrodeposited onto highly stable Ti2AlC substrates as cathodes for hydrogen evolution in sulfuric acid solutions. Journal of Electroanalytical Chemistry, Elsevier, 766, 78-86. [https://doi.org/10.1016/j.jelechem.2016.01.038]The published version: [https://cer.ihtm.bg.ac.rs/handle/123456789/2012

Morphological variation of the Common Lizard (Zootoca vivipara Jacquin, 1787) in the Central Balkans

The variation in some of the morphometric, meristic and qualitative characters of the Common Lizard (Zootoca vivipara) in five population samples from mountains of the Central Balkans was analyzed using univariate and multivariate statistics. The morphological differentiation was greater in males than in females and is more expressed in the morphometric than in the pholidosis and qualitative characters. The largest differences in morphometric traits appeared between the populations from the Šara and Stara Planina mountains. The 'median' pileus pattern generally prevailed, with the appearance of other states in a certain proportion in some of the populations. Further analyses of the possible morphological and ecological distinctions of the population from Mt Tara are proposed.U ovom radu analizirana je morfološka varijabilnost populacija planinskog guštera (Zootoca vivipara) iz centralnog dela Balkanskog poluostrva u pogledu većeg broja morfometrijskih, merističkih i kvalitativnih karaktera pomoću univarijantih i multivarijantnih statističkih metoda. Morfološka diferencijacija populacija je više izražena kod mužjaka nego kod ženki i to znatno više u morfometrijskim karakterima nego u folidozi i kvalitativnim karakterima. Najveće razlike u pogledu morfometrijskih karaktera su utvrđene između populacija sa Šar-planine i Stare planine. Dominira konstelacija pileusa 'median' tipa, sa pojavom manjeg procenta ostalih stanja u pojedinim populacijama. Predlažu se dalje analize moguće morfološke i ekološke različitosti populacije sa planine Tare.Projekat ministarstva br. 143052: Patterns of amphibian and reptile diversity on the Balkan Peninsul

Dielectric barrier discharge in water solution treatment

Application of coaxial dielectric barrier discharge (DBD) reactor for treatment of different water solutions was studied. In this reactor the circulating liquid is a part of discharge electrode configuration. Thus liquid is directly exposed to UV radiation and reactive species like ozone, radicals, ions and electrons. This configuration of DBD also offers to operate the plasma with and without water falling film at one of the electrodes. Thus it can act as a plasma reactor for gas treatment and as a scrubber for soluble compounds in a gas phase, simultaneously. Here we present measurement of hydroxyl radical ("OH) in plasma treated distilled water as well as treatment of phenols, textile dyes, medicaments, herbicides and detergents