Electrodeposition of NiMo alloy coatings and their characterization as cathodes for hydrogen evolution in sodium hydroxide solution

The hydrogen evolution reaction on electrodeposited NiMo alloy coatings, as well as their electrochemical properties in NaOH solutions have been investigated by polarization measurements, cyclic voltammetry and EIS technique. It is shown that NiMo alloy coatings electrodeposited from pyrophosphate-sodium bicarbonate bath possess high catalytic activity for hydrogen evolution in NaOH solutions. Their stability in 1M NaOH at 25 0C under the condition of reverse polarization is shown to be very good, while in 33% NaOH at 850C (conditions of industrial electrolysis) electrodeposited NiMo alloy coatings exhibit also high catalytic activity, but low stability, as a consequence of massive dissolution of alloy coatings under the condition of reverse polarization

Electrodeposition of cobalt powders with novel three-dimensional structure

Novel three-dimensional cobalt powder structures were successfully prepared by electrodeposition. Electrodeposited cobalt powder was characterized by scanning electron microscopy (SEM) and light microscopy. It was possible to control the morphology and structure of cobalt particles by adjusting process parameters of electrodeposition such as current density and type of working electrode. The morphology and structure of cobalt powders were investigated and the formation mechanism of agglomerate was also discussed

Corrected accelerated service life test of electrodeposited NiSn alloys and Ni as cathodes for industrial alkaline water electrolysis

The "corrected accelerated service life test for hydrogen evolution reaction" (CASLT-HER), designed for application of certain electrode materials as cathodes in the cell for alkaline water electrolysis in 30 % KOH at 80 degrees C, was performed at electrodeposited NiSn alloy and Ni 40 mesh electrodes. The Ni 40 mesh was slightly etched, while the NiSn alloy coating was electro-deposited from the bath containing pyrophosphate, glycine, SnCl2 and NiCl2 onto Ni 40 mesh to the thickness of approximately 40 mu m. It is shown that the NiSn cathode possess from maximum 0.77 V to minimum 0.30 V better over-potential than the Ni 40 mesh electrode during the 5 years of their exploitation at the conditions of industrial alkaline water electrolysis. It is also shown that both electrodes should be held at j = -0.3 A cm(-2) for at least 5 h in order to establish stable overpotential response. The limiting overpotential values for applying cyclic voltammetry (CVs, to mimic "polarity inversion") should be determined in a separate experiment before the CASLT-HER and should be adjusted during the application of CVs

Numerical methods for generation and characterization of disordered aperiodic photonic lattices

We introduce numerical modeling of two different methods for the deterministic randomization of two-dimensional aperiodic photonic lattices based on Mathieu beams, optically induced in a photorefractive media. For both methods we compare light transport and localization in such lattices along the propagation, for various disorder strengths. A disorder-enhanced light transport is observed for all disorder strengths. With increasing disorder strength light transport becomes diffusive-like and with further increase of disorder strength the Anderson localization is observed. This trend is more noticeable for longer propagation distances. The influence of input lattice intensity on the localization effects is studied. The difference in light transport between two randomization methods is attributed to various levels of input lattice intensity. We observe more pronounced localization for one of the methods. Localization lengths differ along different directions, due to the crystal and lattice anisotropy. We analyze localization effects comparing uniform and on-site probe beam excitation positions and different probe beam widths

Mehanizam i kinetika elektrosorpcije sulfatnih anjona na (111) pljosni srebra

The processes of adsorption of sulphate anions onto the (111) face of silver have been investigated by analysis of the cyclic voltammetry and potcntiostatic pulse results. It was shown, by fitting the experimentally recorded θ - E dependences, that the adsorption of anions follows Frumkin adsorption isotherm. The adsorbed structure was found to be less dense than expected for the dense packed anion monolayer and the process was characterized by high value of the interaction parameter and the Gibbs energy of adsorption (f = 16.5 and ΔGoads.θ→0 = - 64 kJ mol 1). From the slope of the Ep.a - log (c0) dependence it was concluded that complete charge transfer between the adsorbed anions and the silver substrate occurs. This is supported by the Ep.a - log v linear dependence in the region of high sweep rates (v > 10 V s 1) with rational value of line slope (≈ 60 mV dec 1) which is possible only if the complete charge transfer reaction occurs. The elcctrosorption process of sulphate anions was found to be complex electrochemical reaction, taking place through three steps. It was proposed that the rate-determining step is the second step, i.e., the electrochemical formation of (SO4)ads species.Proučavan je proces adsorpcije sulfatnih anjona na (111) pljosni monokristalasrebra metodama ciklične voltametrije i potenciostatskih pulseva. Na osnovu eksperimentalno određenih q–E zavisnosti pokazano je da se na adsorpciju može primeniti Frumkinova adsorpciona izoterma. Nađeno je da je gustina adsorbovanog slojamanja nego kada bi sloj bio maksimalno moguće gusto pakovan kao i da adsorpcijukarakterišu visoke vrednosti Frumkinovog parametra interakcije (f = 16,5) i Gibsoveenergije adosrpcije (DGºads,q®0 = –64 kJ mol). Na osnovu nagiba zavisnosti Ep,a –log (c0)zaključeno je da se pri elektrosorpciji odigrava i potpuna izmena naboja anjona sasupstratom. Ovaj zaključak podržava dobijena linearna zavisnost Ep,a – log v u oblastivelikih brzina promene potencijala (v>10 V s–1) sa racionalnom vrednošću nagiba (»60mV dek–1), a koja se može dobiti samo pri odigravanju potpune razmene naboja. Utvrđenoje da je elektrosorpcija sulfatnih anjona složena elektrohemijska reakcija koja seodigrava u tri stupnja. Stupanj koji određuje brzinu ukupne reakcije je drugi stupanj,elektrohemijsko stvaranje intermedijera (SO4)ads

Chemometric approach to the development of HPLC/UV and HPLC/MS methods for determination and stability testing of torasemide and its impurities

Torasemid je diuretik Henleove petlje sa sličnim dejstvom kao furosemid. Koristi se u stanjima edema udruženim sa srčanom bolešću, uključujući i plućni edem, kao i u slučajevima oboljenja bubrega i jetre. Takoñe se koristi u tretmanu hipertenzije, samostalno ili u kombinaciji sa drugim antihipertenzivima. Torasemid ostvaruje dejstvo u uzlaznom, debljem kraku Henleove petlje inhibirajući tubularnu reapsorpciju natrijuma (Na+) i hlora (Cl-) ograničavanjem natrijum/hlorid/kalijum prenosnog sistema. U kontroli kvaliteta farmaceutskih proizvoda testovi identifikacije i odreñivanja sadržaja aktivne supstance i nečistoća su veoma važni sa ciljem da se obezbedi visok kvalitet proizvoda, bez promena u hemijskim, farmakološkim ili toksikološkim karakteristikama. Prema ICH smernicama, sve nečistoće prisutne u farmaceutskom doziranom obliku u količini većoj od 0.1% moraju se ispitati. Za istovremeno odreñivanje torasemida i njegovih nečistoća razvijene su nove, osetljive i pouzdane HPLC/UV i HPLC/MS metode. Kompletno hromatografsko ponašanje ispitivanih supstanci i pronalaženje optimalnih hromatografskih uslova ostvareno je uz upotrebu eksperimentalnog dizajna. Frakcioni faktorski dizajn je korišćen za izbor varijabli koji značajno utiču na hromatografsko razdvajanje. Puni faktorski dizajn je korišćen za optimizaciju tih varijabli kako bi se postiglo zadovoljavajuće razdvajanje izmeñu ispitivanih supstanci u najkraćem mogućem vremenu trajanja analize. Nakon toga, obe metode su uspešno validirane u skladu sa ICH smernicama i primenjene za ispitivanje farmaceutskog doziranog oblika, torasemid tableta. Kako u literaturi postoji nedostatak informacija o degradacionom mehanizmu torasemida, to su aktivna farmaceutska supstanca torasemid i farmaceutski dozirani oblik (torasemid tablete) podvrgnuti studijama forsirane degradacije sa ciljem da se identifikuju potencijalni degradacioni proizvodi i ustanovi mogući degradacioni put i sveukupna stabilnost torasemida. Studija je sprovedena u skladu sa ICH smernicama, a uzorci su izlagani uslovima hidrolize (kisele, bazne i neutralne), oksidacije, fotolize i termalne degradacije. Za karakterizaciju nastalih degradacionih proizvoda primenjene su HPLC/UV i HPLC/MSn tehnike. Kvadrupolni i jonski trap maseni analizatori su korišćeni da se ustanovi način fragmentacije degradacionih proizvoda...Torasemide is a loop diuretic with actions similar to those of furosemide. Torasemide is used for edema associated with heart failure, including pulmonary edema, and with renal and hepatic disorders. It is also used in the treatment of hypertension, either alone or with other antihypertensives. It acts in the ascending limb of the loop of Henle by inhibiting tubular reapsorption of sodium and chloride and interacting with the sodium/chloride/potassium co-transport system. In the quality control of pharmaceutical products identification and quantification of the active ingredient and its impurities is very important in order to achieve a high quality of the product, without change in chemical, pharmacological and toxicological properties. According to ICH guidelines, determination of impurities present in pharmaceutical dosage forms above 0.1% is necessary. A new, sensitive and reliable HPLC/UV and HPLC/MS methods for simultaneous determination of torasemide and its impurities were developed. The complete chromatographic behavior and optimal chromatographic conditions were evaluated with the assistance of experimental design. The fractional factorial design was used for selection of variables which significantly influence the chromatographic separation of the investigated substances. Full factorial design was used for optimization of these variables in order to achieve satisfactory resolution between all investigated substances with the shortest possible analysis time. Afterwards, both analytical methods were successfully validated in accordance with ICH guidelines and the applicability of the proposed methods on the torasemide tablet dosage form has been demonstrated. As the degradation mechanism of torasemide has been lacking in the literature, torasemide active pharmaceutical ingredient and torasemide tablets drug product were subjected to forced degradation studies in order to identify the potential degradation products and establish the possible degradation pathways and intrinsic stability of the drug. The study was performed according to ICH guidelines and samples were exposed to hydrolysis (acid, base and neutral), oxidation, photolysis and thermal degradatio

Coal-fired power plants energy efficiency and climate change: Current state and future trends

Termoelektrane na fosilna goriva, pre svega ugalj, emituju velike količine ugljen dioksida, koji se smatra glavnim uzročnikom fenomena globalnog zagrevanja. Smanjenje emisije CO2 u energetskom sektoru je postalo jedan od osnovnih prioriteta svih nacionalnih vlada. Sa druge strane, globalno zagrevanje direktno utiče na proizvodnju energije. Ovaj uticaj se pre svega ogleda u mogućnosti odvođenja otpadne toplote, neophodnog za rad postrojenja. U doglednoj budućnosti efikasnost rada postojećih termoenergetskih postrojenja opadati, ukoliko se ne ulože dodatni napori kako bi se unapredio njihov rad, posebno imajući u vidu optimizaciju rada kondenzacionog dela postrojenja, a ovo opet vodi povećanoj emisiji CO2. Predviđeni porast potrošnje energije dodatno podvlači ovaj problem.U radu je dat pregled današnjih metoda za smanjenje emisije CO2 u atmosferu, ali je osnovni cilj rada da ukaže na mogućnosti povećanja energetske efikasnosti postojećih postrojenja, uz relativno mala ekonomska ulaganja, čime bi se smanjili i ekološki problemi. Prikazan je uticaj porasta temperature rashladne vode i vazduha na energetsku efikasnost termoelektrana u Srbiji sa protočnim i povratnim sistemom hlađenja. Rezultati su dobijeni na osnovu originalnih matematičkih modela i numeričkih simulacija, koje su autori predstavili u drugim radovima. Dobijeni rezultati mogu biti od koristi kako pri revitalizaciji postojećih, tako i pri projektovanju novih termoenergetskih kapaciteta.Coal-fired power plants emit large amounts of CO2, which constitutes one of the largest causes of global warming. Reducing CO2 emissions in the energy sector has become a top priority for national governments. On the other hand, fossil energy production is also affected by air and water temperatures. Local weather conditions affect the capacity of cooling towers and natural water bodies to transfer waste heat from steam condensers to the atmosphere. Without technology-based improvements in cooling system efficiency, the steam-cycle energy efficiency would decrease. This again leads to increased consumption of fossil fuels and thus increasing emissions of CO2. Increasing in global energy demand aggravates this issue. In this paper, the overview of currently actual methods for CO2 reduction is given. The main objective, however, is to find a cost-effective solution for increasing the energy efficiency of existing plants in Serbia. The overview of cooling water temperature increase impact on the energy efficiency in Serbian power plants is given, based on meteorological data and numerical simulation. This study is done for both, power plants with once-through and with closed cycle cooling system. Obtained results could be used as useful guidelines in design of the new power plants and also in improving existing power plants performances

CREATING AS DECEPTION: THE CONCEPT OF ‘CULTURE OF ERASUREʼ IN MURIEL SPARKʼS NOVEL THE FINISHING SCHOOL

This paper will deal with the peculiar, Scottish view of the position of creative imagination in literature. A specific cultural background for this view will be presented, together with the reading of one of the latest novels by Muriel Spark, The Finishing School (2004). Concepts such as ‘culture of erasure,’ ‘Calvinism’ and its cultural heritage in the modern Scotland, as well as the role ‘imagination’ plays in the national spirit against the specific Scottish historical background will be investigated into. The focus of the paper will be less on Muriel Spark as an individual author, rather, the point of the paper will be how to contextualise some themes within Spark’s novel within the specificity of a national culture and history

Coal-fired power plants energy efficiency and climate change: Current state and future trends

Termoelektrane na fosilna goriva, pre svega ugalj, emituju velike količine ugljen dioksida, koji se smatra glavnim uzročnikom fenomena globalnog zagrevanja. Smanjenje emisije CO2 u energetskom sektoru je postalo jedan od osnovnih prioriteta svih nacionalnih vlada. Sa druge strane, globalno zagrevanje direktno utiče na proizvodnju energije. Ovaj uticaj se pre svega ogleda u mogućnosti odvođenja otpadne toplote, neophodnog za rad postrojenja. U doglednoj budućnosti efikasnost rada postojećih termoenergetskih postrojenja opadati, ukoliko se ne ulože dodatni napori kako bi se unapredio njihov rad, posebno imajući u vidu optimizaciju rada kondenzacionog dela postrojenja, a ovo opet vodi povećanoj emisiji CO2. Predviđeni porast potrošnje energije dodatno podvlači ovaj problem.U radu je dat pregled današnjih metoda za smanjenje emisije CO2 u atmosferu, ali je osnovni cilj rada da ukaže na mogućnosti povećanja energetske efikasnosti postojećih postrojenja, uz relativno mala ekonomska ulaganja, čime bi se smanjili i ekološki problemi. Prikazan je uticaj porasta temperature rashladne vode i vazduha na energetsku efikasnost termoelektrana u Srbiji sa protočnim i povratnim sistemom hlađenja. Rezultati su dobijeni na osnovu originalnih matematičkih modela i numeričkih simulacija, koje su autori predstavili u drugim radovima. Dobijeni rezultati mogu biti od koristi kako pri revitalizaciji postojećih, tako i pri projektovanju novih termoenergetskih kapaciteta.Coal-fired power plants emit large amounts of CO2, which constitutes one of the largest causes of global warming. Reducing CO2 emissions in the energy sector has become a top priority for national governments. On the other hand, fossil energy production is also affected by air and water temperatures. Local weather conditions affect the capacity of cooling towers and natural water bodies to transfer waste heat from steam condensers to the atmosphere. Without technology-based improvements in cooling system efficiency, the steam-cycle energy efficiency would decrease. This again leads to increased consumption of fossil fuels and thus increasing emissions of CO2. Increasing in global energy demand aggravates this issue. In this paper, the overview of currently actual methods for CO2 reduction is given. The main objective, however, is to find a cost-effective solution for increasing the energy efficiency of existing plants in Serbia. The overview of cooling water temperature increase impact on the energy efficiency in Serbian power plants is given, based on meteorological data and numerical simulation. This study is done for both, power plants with once-through and with closed cycle cooling system. Obtained results could be used as useful guidelines in design of the new power plants and also in improving existing power plants performances