Preparation of zinc oxide varistors with submicronic grain size and ultra-high breakdown field

Cink-oksidni varistori sa izrazito visokim poljem proboja potrebni su u savremenim tehnologijama, gde je poželjno da prenaponska zaštita bude što manjih dimenzija, a istovremeno i električno funkcionalna. U ovoj doktorskoj disertaciji za postizanje visokog polja proboja primenjena su dva smera: dobijanje varistora iz pojedinačno sintetisanih nanodimenzionalnih prekursora (Co/Mn-dopiranog ZnO, Bi2O3 i Sb2O3), kao i metoda uvođenja Bi2O3 i Sb2O3 aditiva u već sintetisani Co/Mn-dopirani ZnO preko rastvora odgovarajućih soli...Zinc oxide varistors with ultra-high breakdown field are necessary for applications in modern technologies, where the overvoltage protection should be simultaneously as small as possible and electrically functional. Preparation of ultra-high breakdown field varistors, that was presented in this work, included two routes: preparation of varistors via separately synthesized nanoprecursors (Co/Mn-doped ZnO, Bi2O3 and Sb2O3), and also by the addition of Bi2O3 and Sb2O3 additives through the solutions of appropriate salts..

Utjecaj prijeoperacijske respiracijske rehabilitacije kod kardiokirurških bolesnika

The aim of the study was to evaluate the effects of preoperative respiratory rehabilitation on functional capacity, length of stay in intensive care unit (ICU), duration of mechanical ventilation (MV) and total hospitalization, as well as to estimate arterial blood gas (ABG) values in patients undergoing cardiac surgery. Nineteen patients were included in the randomized observational study, divided into two groups: group A (intervention) and B (control). Preoperative and postoperative rehabilitation was performed in group A, and only postoperative rehabilitation in group B. Rehabilitation was carried out according to a predefined protocol. We used ABG to evaluate respiratory function, two-minute walk test (2MWT) and sit-to-stand test to assess functional capacity. The following data were obtained from medical documentation: duration of MV, length of stay at ICU, occurrence of postoperative pulmonary complications, and length of total hospitalization in both groups. Significant between-group difference was found for the length of total hospitalization and duration of MV (p<0.05 both). Analysis of the mean values of 2MWT on the last day of hospitalization (p=0.005), sit-to-stand test before surgery (p=0.022) and on the last day of hospitalization (p=0.008) showed statistically significant differences. The length of hospital stay significantly correlated with preoperative rehabilitation in group A (r=0.885; p<0.0001). There was no difference in ABG parameters between the groups. The study showed that preoperative respiratory rehabilitation had an effect on reducing duration of MV and length of total hospitalization, and improved functional capacity.Cilj rada je bio procijeniti učinak prijeoperacijske respiracijske rehabilitacije na funkcionalni kapacitet, dužinu boravka u jedinici intenzivnog liječenja (JIL), trajanje mehaničke ventilacije (MV) i ukupnu hospitalizaciju te procijeniti vrijednosti plinske analize arterijske krvi (ABG) kod bolesnika podvrgnutih kardiokirurškim operacijama. U radomiziranu opservacijsku studiju bilo je uključeno 19 bolesnika podijeljenih u dvije skupine: skupina A (ispitivana) i B (kontrolna). Prijeoperacijska i poslijeoperacijska rehabilitacija provedena je u skupini A, a samo poslijeoperacijska rehabilitacija u skupini B. Rehabilitacija je provođena prema unaprijed utvrđenom protokolu. Rabili smo parametre ABG za procjenu respiracijske funkcije, a za procjenu funkcionalnog kapaciteta 2-minutni test hoda (2MWT) i sit-to-stand test. Sljedeći podaci prikupljeni su iz medicinske dokumentacije: dužina MV, dužina boravka u JIL, pojava komplikacija i dužina ukupne hospitalizacije. Nađena je značajna razlika između skupina za dužinu ukupne hospitalizacije (p<0,05) i dužinu MV (p<0,05). Analiza srednjih vrijednosti 2MWT posljednjeg dana hopitalizacije (p=0,005), sit-to-stand testa prije operacije (p=0,022) i posljednjeg dana hospitalizacije (p=0,008) između skupina pokazala je statistički značajnu razliku. Dužina hospitalizacije je značajno korelirala s prijeoperacijskom rehabilitacijom u skupini A (r=0,885; p<0,0001). Nije bilo razlike u parametrima ABG između skupina. Studija je pokazala da je prijeoperacijska respiracijska rehabilitacija utjecala na smanjenje dužine MV, dužinu trajanja ukupne hospitalizacije te na poboljšanje funkcionalnog kapaciteta

The forgotten Toponyms Within the Historical Core of Split

U ovom se radu iznosi dio rezultata istraživanja toponimije grada Splita, koja je kao tema zahvaćena znanstvenim projektom na Filozofskom fakultetu Sveučilišta u Splitu. Obrađuju se pretežito zaboravljeni odonimi koji su ostali zabilježeni u povijesnim vrelima, a neki od njih sačuvali su se danas u imenima ulica. Ripa Maris, dio uvale splitske luke zapadno od zida Dioklecijanove palače, nazvan po položaju uz more; Fenestris, prostor u jugoistočnom dijelu Palače, nazvan po prozorskim otvorima; Sdoria, srednjovjekovni naziv, nastao prema konsistorijalnoj dvorani splitske Nadbiskupije; Pistura, prostor zapadno od Palače, nazvan po sporednim gradskim vratima; Obrov, prostor zapadno od srednjovjekovnih splitskih zidina, nazvan po obrambenom rovu; Šperun, zapadni polubastion splitskih bedema, nastao od talijanske riječi sperone (kljun). Autori su koristili povijesna vrela i kritičkim razmatranjem dosadašnjih tumačenja došli do nekih novih zaključaka o obrađenim toponimima. Pet toponima romanskog su porijekla, a jedan hrvatskoga.The authors present some results of the research on the toponymy of Split as the topic of a scientific project carried out at the Academy of Arts, University of Split. Several toponyms are presented, recorded in the documents but mostly forgotten, some of them preserved in the form of the names of streets. - Ripa maris, a part of a bay of the port of Split west of the wall of Diocletian’s palace, named after the position on the very coast, - Fenestris, the site in the south-east part of the Palace, named after the windows on the façade, - Sdoria, the mediaeval name for the former consistorial hall of the Archdiocese of Split, - Pistura, the area to the west of the Palace, named after the accessory entrance, - Obrov, the area to the west of the mediaeval town walls, named after the defence ditch, - Šperun, the western semi-bastion of the town walls; the toponym originates from the Italian word sperone (rostrum). The authors used historical sources and with a critical analysis of the past interpretation have come to some new conclusions about the examined toponyms. Five among the analysed toponyms are of Romance, and one of Croatian origin

Potencijalna korist od retrospektivne uporabe neutronskih monitora u svrhu bolje procjene izloženosti ionizirajućem zračenju na međunarodnim letovima – pitanja proizašla iz mjerenja pasivnim neutronskim dozimetrom i simulacije softverom EPCARD tijekom naglih promjena u solarnoj aktivnosti

Since air transport became more accessible, more and more people have been exposed to ionising radiation of cosmic origin. Measuring the neutron dose equivalent is a good approximation of total ambient dose equivalent, as neutrons carry about 50 % of the dose at flight altitudes. The aim of our study was to compare our measurements of the neutron component of secondary cosmic radiation dose, taken with passive dosimeters, with the data obtained from a simulation generated by EPCARD software, which is common in assessing flight crew exposure to ionising radiation. We observed deviations (both above and below) from the expected proportion of the neutron component (between 40 and 80 %), which pointed to certain issues with actual passive dosimeter measurement and the EPCARD simulation. The main limitation of the dosimeter are large uncertainties in high energy neutron response, which may result in underestimation of neutron dose equivalent. The main drawback of the software simulation is monthly averaging of solar potential in calculations, which can neglect sporadic high energy events. Since airlines worldwide almost exclusively use software (due to costs and convenience) to estimate the dose received by their crew, it is advisable to retrospectively recalculate the dose taking into account neutron monitor readings when solar activity changes.Budući da je zračni promet postao dostupniji, sve je više ljudi izloženo ionizirajućem zračenju kozmičkoga podrijetla. Neutronska komponenta sekundarnoga kozmičkog zračenja mjerena je pasivnim dozimetrom koji se sastoji od čvrstog detektora nuklearnih tragova i konvertera. Dobiveni rezultati uspoređeni su s podatcima dobivenima simulacijskim softverom EPCARD. Mjerenje neutronskoga doznog ekvivalenta na zrakoplovnim visinama dobra je aproksimacija ukupnog ambijentalnog doznog ekvivalenta, jer na zrakoplovnim visinama neutroni pridonose s oko 50 % doze. Međutim, uočena su određena odstupanja (i iznad i ispod) ove vrijednosti zbog varijacija u Sunčevoj aktivnosti. Ta su odstupanja očita kada se usporede izmjereni neutronski dozni ekvivalent i ukupni ambijentalni dozni ekvivalent dobiven simulacijom. Glavno ograničenje dozimetra velika je nesigurnost u području visokoenergetskih neutrona, što može rezultirati podcjenjivanjem neutronskoga doznog ekvivalenta. Glavni je nedostatak softverske simulacije u korištenju prosječnoga mjesečnog solarnog potencijala u proračunima, zbog čega se utjecaj sporadičnih visokoenergetskih događaja može previdjeti. Budući da se zrakoplovne tvrtke diljem svijeta gotovo isključivo koriste softverom za procjenu doze koju prima njihova posada (zbog troškova i jednostavnosti), preporučljivo je u slučaju promjene u Sunčevoj aktivnosti retrospektivno preračunati dozu

One-pot synthesis of biocompatible NaYF4:Yb,Er nanoparticles for cell labeling

In modern medical research, great attention has been focused to the development of the new biomarkers which include up-converting nanoparticles (UCNPs). Their optical response is triggered by NIR radiation that achieves deeper tissue penetration when compared with traditionally used fluorophores. In this work, biocompatible NaYF4: Yb, Er nanoparticles were synthesized by polymer assisted one-pot solvothermal processing using chitosan or poly(lacticco- glycolic acid). X-ray powder diffraction and electron microscopy results revealed differences in crystal arrangement and morphology of the as-synthesized particles. Fourier transform infrared spectroscopy confirmed the presence of corresponding polymers moiety on UCNPs surface providing their biocompatibility and low cytotoxicity towards human gingival fibroblasts (HFG). As a consequence of efficient up-conversion, prominent green emission (between 512-533nm and between 533-560nm) as well as red emission (630-690nm) were recorded in the particles photoluminescence spectra, and these are applied further in the visualization of the HFG using the laser scanning microscopy with a NIR laser source

Dijabetička polineuropatija i rizik od pada: strah od pada i drugi čimbenici

The aim of the study was to analyze postural stability, walking speed and fear of falling in patients with diabetic polyneuropathy (DPN) in order to determine the risk factors for falls, as well as the effect of DPN characteristics as additional factors. A sample of 48 patients with type 2 diabetes and DPN were enrolled in this non-randomized observational study. The patients were divided into two groups of fallers and non-fallers. All subjects underwent evaluation with the Functional Reach Test (FRT), Tinetti Falls Efficacy Scale (Tinetti FES) and 10-Meter Walk Test (10MWT). Neuropathy was quantified with the Michigan Neuropathy Screening Instrument (MNSI, Questionnaire part) and 5.07/10-g Semmes Weinstein monofilament examination (SW-ME). The 10MWT and SW-ME were significantly different between the faller and non-faller groups (p<0.05). Duration of DPN correlated positively with SW-ME (p=0.005) in the faller group. FES showed significant positive correlation with MNSI and negative correlation with 10MWT in the non-faller group. Logistic regression analysis revealed that SW-ME was significantly associated with the probability of falling (p=0.0076; OR=1.378). Study results suggested that the loss of protective sensitivity of foot could be a risk factor for falls in people suffering from type 2 diabetes.Cilj ovoga rada bio je analizirati posturalnu stabilnost, brzinu hoda i strah od pada u bolesnika s dijabetičkom polineu-ropatijom (DPN) kako bi se utvrdili rizični čimbenici za padove, kao i utjecaj karakteristika DPN kao dodatnih čimbenika. Uzorak od 48 bolesnika s dijabetesom tipa 2 i DPN uključen je u ne-randomiziranu opservacijsku studiju. Sudionici su ­podijeljeni u dvije skupine: skloni padovima (faller) i neskloni padovima (non-faller). Svi ispitanici su podvrgnuti ocjeni ­pomoću sljedećih testova: Functional Reach Test (FRT), Tinetti Falls Efficacy Scale (Tinetti FES) i 10-Meter Walk Test (10MWT). Neuropatija je kvantificirana pomoću Michigan Neuropathy Screening Instrument (MNSI) (Upitnik-dio) i testa 5,07/10-g Semmes Weinstein monofilament (SW-ME). Rezultati na 10 MWT i SW-ME su bili značajno različiti između skupina bolesnika sklonih padovima i onih nesklonih padovima (p<0,05). Trajanje DPN bilo je pozitivno povezano sa ­SW-ME (p=0,005) u skupini bolesnika sklonih padovima. Ljestvica FES je značajno pozitivno korelirala s MNSI i negativno s 10MWT u skupini bolesnika nesklonih padovima. Logistička regresijska analiza je pokazala da je SW-ME značajno pove-zana s vjerojatnošću pada (p=0,0076; OR=1,378). Studija je ukazala na to da je gubitak zaštitne osjetljivosti stopala znača-jan čimbenik za pad kod osoba koje pate od dijabetesa tipa 2

Financiranje poslovanja poduzeća emisijom dionica - pregled i trendovi u Republici Hrvatskoj

Svoj rast i razvoj poduzeća financiraju na različite načine ovisno o tome u kojoj fazi poslovanja se poduzeće nalazi. U fazi zrelosti, odnosno ekspanzije, tri su prevladavajuća načina na koje se poduzeće može financirati: 1) iz zadržane dobiti, 2) financiranjem putem duga, te, 3) izdavanjem dionica. Predmet istraživanja ovoga rada su dionička društva i financiranje putem izdavanja dionica. U radu su prikazana glavna obilježja i načini financiranja poslovanja putem emisije dionica. Analiziraju se vrste dionica, proces izdavanja i sudionici te se opisuju elementi i procesi inicijalne i sekundarne javne ponude dionica. Financiranje poslovanja poduzeća putem povlaštenih dionica, koje je relativno slabo zastupljeno kao način financiranja, prikazano je na konkretnom primjeru kupnje povlaštenih dionica Podravke d.d. od strane Europske banke za obnovu i razvoj. U radu su također definirane inicijalne i sekundarne javne ponude dionica u Republici Hrvatskoj u razdoblju od 2006 do danas

Citrate assisted solvothermal synthesis of beta-NaYF4: Yb, Er up-converting nanoparticles

Thanks to the unique optical properties, up-converting nanoparticles (UCNPs) have a wide application in optoelectronics, forensics, security and biomedicine. The synthesis of the most efficient hexagonal β-NaYF4: Yb/Er phase is usually performed through thermal decomposition of organic precursors which could cause the UCNP cytotoxicity. Since cubic polymorph is kinetically more stable than hexagonal, we used citric acid and Na-citrate for the nucleation of hexagonal NaYF4: Yb, Er phase in nanosized particles. Additionally, effect of different precipitation agents (NaF, NH4F and NH4HF2) used during solvothermal synthesis is explored. The XRPD analysis showed that using of citric acid led to a product composed from mixture of cubic and hexagonal NaYF4: Yb/Er phase, while the presence of Na-citrate influences the nucleation of well crystallized hexagonal β-NaYF4: Yb/Er phase, regardless of precipitation agents used. All samples are composed of polycrystalline spherical particles which size is influenced by the precursor chemistry. UCNPs emit intense green emission due to the (2H11/2, 4S3/2) → 4I15/2 electronic transitions, after been excited with infrared light (λ=978 nm)

Effect of Gd3+ introduction on YF3: Yb, Er structural, morphological and optical properties

Monosized up-converting nanoparticles (UCNPs) with a spherical shape and biocompatible surface have a wide application in biomedicine as new cell markers or light-triggered drug delivery agents. The synthesis of the hexagonal β-NaYF4:Yb/Er phase is of a great interest, because of its most efficient up-conversion luminescence. Beside it, synthesis of the UCNPs based on YF3:Yb/Er phase is also attractive due to its orthorhombic phase arrangement and fact that higher concentration of dopants could be introduced in such crystal lattice. In this work the synthesis of pure and Gd-doped YF3:Yb/Er phases were performed through hydro/solvo thermal method using a biocompatible chitosan as a surfactant. The XRD analysis showed that independently of the gadolinium content formation of the orthorhombic phase is achieved, but intensity of the green emission due to the (2H11/2, 4S3/2) → 4I15/2 electronic transitions was highest for un-doped YF3:Yb/Er sample