the structure of ceramic materials

U arheologiji je keramika najčešći pokretni materijal koji se pronalazi prilikom istraživanja. Pri njezinoj obradi važno je poznavati strukturu keramičkih materijala. Varijacije u strukturi javljaju se zbog kemijskih svojstava same gline, primjesa u glini te razlika u procesu pečenja. U radu se iznose podaci o primjesama koje se prirodno nalaze u glini i onima koje joj se naknadno dodaju, a važne su zbog funkcionalnih karakteristika kao što su temperaturna otpornost, porozitet i, ponajprije, boja i čvrstoća pečenoga proizvoda. Varijacije u strukturi keramičkoga materijala javljaju se i zbog razlika u procesu pečenja koji podrazumijeva vrijeme pečenja, temperaturu i atmosferu tijekom gorenja i hlađenja. Promjene koje nastaju pri pečenju (na otvorenome ognjištu ili u zatvorenoj peći) uključuju: isparavanje, termičko raspadanje glinenih minerala i sinteriranje, vitrifikaciju te hlađenje i pražnjenje peći. Za istraživanje strukture keramičkoga materijala koriste se razne metode. Njima se nastoji utvrditi sastav glinene smjese i postoci raznih primjesa te opisati kemijski procesi koji nastaju prilikom pečenja.In archaeology, ceramics are the most common movable materials discovered during the course of excavations. Knowledge of the structure of ceramic materials is vital to its analysis. Variations in structure appear due to the chemical properties of the clay itself, additives in the clay and differences in the firing process. This work presents data on additives naturally found in clay and those subsequently added, and these are important due to functional features such as resistance to temperature extremes, porosity and, above all, the colour and tenacity of the fired product. Variations in the structure of ceramic materials also appear due to differences in the firing process, which implies firing duration, temperature and atmosphere during heating and cooling. Changes which emerge during firing (in open hearths or in closed kilns) include: evaporation, thermal decomposition of clay materials and sintering, vitrification and cooling and emptying of kilns. Various methods are used to study the structure of ceramic materials. They are used in an attempt to ascertain the composition of the clay and percentages of different additives and to describe the chemical processes that occur during firing

the structure of ceramic materials

U arheologiji je keramika najčešći pokretni materijal koji se pronalazi prilikom istraživanja. Pri njezinoj obradi važno je poznavati strukturu keramičkih materijala. Varijacije u strukturi javljaju se zbog kemijskih svojstava same gline, primjesa u glini te razlika u procesu pečenja. U radu se iznose podaci o primjesama koje se prirodno nalaze u glini i onima koje joj se naknadno dodaju, a važne su zbog funkcionalnih karakteristika kao što su temperaturna otpornost, porozitet i, ponajprije, boja i čvrstoća pečenoga proizvoda. Varijacije u strukturi keramičkoga materijala javljaju se i zbog razlika u procesu pečenja koji podrazumijeva vrijeme pečenja, temperaturu i atmosferu tijekom gorenja i hlađenja. Promjene koje nastaju pri pečenju (na otvorenome ognjištu ili u zatvorenoj peći) uključuju: isparavanje, termičko raspadanje glinenih minerala i sinteriranje, vitrifikaciju te hlađenje i pražnjenje peći. Za istraživanje strukture keramičkoga materijala koriste se razne metode. Njima se nastoji utvrditi sastav glinene smjese i postoci raznih primjesa te opisati kemijski procesi koji nastaju prilikom pečenja.In archaeology, ceramics are the most common movable materials discovered during the course of excavations. Knowledge of the structure of ceramic materials is vital to its analysis. Variations in structure appear due to the chemical properties of the clay itself, additives in the clay and differences in the firing process. This work presents data on additives naturally found in clay and those subsequently added, and these are important due to functional features such as resistance to temperature extremes, porosity and, above all, the colour and tenacity of the fired product. Variations in the structure of ceramic materials also appear due to differences in the firing process, which implies firing duration, temperature and atmosphere during heating and cooling. Changes which emerge during firing (in open hearths or in closed kilns) include: evaporation, thermal decomposition of clay materials and sintering, vitrification and cooling and emptying of kilns. Various methods are used to study the structure of ceramic materials. They are used in an attempt to ascertain the composition of the clay and percentages of different additives and to describe the chemical processes that occur during firing

The impact of the COVID-19 pandemic on international students’ perception of service quality (Case study of the University of Split)

Purpose: Development opportunities of higher education institutions (HEI) arising from international activities are constantly evolving, increasing at the same time their complexity. Consequently, numerous activities have been created to connect different higher education institutions across Europe, where the biggest challenge of internationalisation today is the European Universities Initiative. In that context, it is important to measure whether the European Union initiative created better resilience to the COVID-19 pandemic. Methodology: Empirical analysis was conducted that included international students who studied at UNIST for one semester during the pandemic. The following descriptive statistics methods were used for data analysis: percentages, mean, frequency distribution, the standard deviation correlation method, as well as the independent-samples t-test and the correlation method. Results: The results show that from the perspective of international students, there is a positive relationship between perceived service quality and internationalisation during the COVID-19 pandemic period. A case study was presented on the internationalisation of the University of Split as one of the first universities that joined the European Universities Initiative. Conclusion: Internationalisation is one of the keys to success if the perceived quality of higher education can be considered as a key to student satisfaction

The Effect of Chewing Gum in the Prevention of Caries

Zubni karijes je zbog svoje rasprostranjenosti u svijetu velik javnozdravstveni problem. Zbog toga ne iznenađuje činjenica da postoji velik broj materijala i postupaka kojima je svrha prevencija nastanka zubnoga karijesa. Jedan je od tih postupaka uporaba guma za žvakanje koje simuliranjem lučenja sline sprječavaju stvaranje dentobakterijskoga plaka na površinu zuba i uklanjaju već akumulirani plak. Ispitivanje je obuhvatilo 16 studenata (12 studentice i 4 studenta) 3., 4. i 5. godine Stomatološkog fakulteta Sveučilišta u Zagrebu. Mjerena je količina lučenja nestimulirane sline za svakoga studenta, stimulirane sline sa štapićima voska preuzetim iz Caries risk test seta (Shaan, Vivadent) te dvije vrste guma za žvakanje Orbit (Wrigley) Winterfresh i Wild Strawberry. Ispitanici su vosak i gume za žvakanje prvo žvakali jednu minutu i svu skupljenu slinu bi progutali, a zatim su žvakali još tri minute i svu su slinu skupljali u graduiranu menzuru. Dobiveni rezultati su istraženi kao srednja vrijednost i standardna devijacija, a njihova razlika putem student t-testa. Također je izračunan i KEP indeks (DMF/t) za svakog ispitanika. Dobiveni rezultati pokazuju znatan porast lučenja stimulirane sline prigodom žvakanja guma za žvakanje u usporedbi sa žvakanjem voska. Također postoji razlika u lučenju sline u odnosu prema okusu gume za žvakanje. Kod gume za žvakanje s okusom Wild Strawberry volumen sline bio je veći. Rezultati ovog istraživanja potvrđuju opravdanost uporabe guma za žvakanje, pogotovo ako uzmemo u obzir da su većina današnjih guma za žvakaknje zaslađene umjetnim sladilima kao što je ksilitol koji ima i protukarijesno djelovanje.Dental caries, because of its spread worldwide, represents a public health problem. It is therefore, not surprising to find a great number of materials and procedures whose goal is the prevention of its formation. One such procedure is use of chewing gums which stimulate the secretion of saliva, thus preventing the formation of dental bacterial plaque on the surface of the teeth as well as a removal of existing plaque. The study included 16 students (12 female and 4 male) of the 3rd, 4th and 5th year of the Dental School of the Zagreb Universitiy. The goal was to measure the quantity of secretion of unstimulated saliva as opposed to that of stimulated saliva for each student, using the wax sticks borrowed from the Caries risk test set (Schaan, Vivadent) and two kinds of Orbit chewing gum (Wrigley: Winterfresh and Wild Strawberry). The examinees first chewed the wax and the chewing gum for one minute and then swallowed all the secreted saliva. Afterwards they chewed for another three minutes, this time collecting the secreted saliva into a calibrated measuring cup. The achived results are expressed as the medium value and standard deviation, the difference between them being noted with Student t-test. KEP index (DMF/t) for each examinee was also calculated. The achived results showed a significant difference in the saliva secretion during the use of chewing gum and the use of wax. There was also a difference in the secretion of saliva regarding the flavour of the chewing gum. The volume of saliva was more when Wild Strawberry was used. The results of the study justify the use of chewing gums, especially if we take into consideration that many of them contain an artificial sweetner, such as xylithol, with a strong anticaries effect

THIN-WALLED POTTERY FROM THE SITE SV. KVIRIN IN SISAK

U radu se obrađuje keramika tankih stijenki s lokaliteta sv. Kvirin, nađena pri zaštitnom arheološkom istraživanju 2003., u bloku A i B, stratigrafskoj jedinici SJ 11, odnosno sloju koji je nastao nakon uništenja prve faze izgradnje rimske Siscije. Analizirana je te statistički obrađena do sada objavljena i obrađena keramika tankih stijenki nađena na području antičke Siscije. S lokaliteta sv. Kvirin analizirano je ukupno 100 ulomaka. Analizirana keramika tankih stijenki koji se razlikuju prema tehnici izrade, fakturi, po obliku te načinu ukrašavanja keramike. Izdvojeno je 11 različitih faktura kojima su dodijeljene oznake Sisc.kts.1–11. Prema načinu ukrašavanja podijeljena je na glatku, ukrašenu urezivanjem, utiskivanjem i apliciranim ukrasom. Usporedbom s ostalim materijalom nađenim u ovom sloju, kao i prema stratigrafiji, može se zaključiti kako je materijal vezan uz kasnotiberijevsko- klaudijevsko razdoblje.This paper discusses the thin-walled pottery from the site Sv. Kvirin (Saint Quirinus) , found during the 2003 rescue excavation in sectors A and B, stratigraphic unit SU 11, i.e. the layer formed after the destruction of the first phase of construction of the Roman Siscia. The published thinwalled pottery from the area of ancient Siscia has been examined and statistically analyzed. 100 fragments have been examined from the site Sv. Kvirin. The analyzed thinwalled pottery varies according to the clay body texture, production technique, shape and decoration method. 11 different structural compounds have been singled out and labeled Sisc.kts.1–11. According to the decoration techniques, the pottery was divided into smooth-surface ware, ware with incised decoration, indentation and appliqués. Compared to the rest of the material from this layer, as well as the stratigraphy, it can be concluded that the material dates to the late Tiberian-Claudian period

Endodontic Treatment of 46 with Four Root Canals: Case Presentation

Pacijentica u dobi od 30 godina javila se zbog povremenih smetnji u području 46. Nakon kliničkog pregleda kojim je utvrđena rubna pukotina na ispunu, bolnost na okomitu perkusiju i avitalnost zuba, učinjene su osnovne rtg snimke na kojima je vidljiva periapeksna promjena u području distalnoga korijena. Provedena je instrumentacija četiriju korijenskih kanala modificiranom “Balancedforce” tehnikom. Kanali su ispunjeni Diaket punilom i standardiziranim gutaperka štapićima tehnikom hladne lateralne kondenzacije. U svim fazama provedene su radiološke kontrole.A female patient, aged 30 years, was admitted because of temporary pain in area 46. A clinical examination established a lateral fissure in the filling, sensitivity to vertical percussion and avitality of the tooth. Preoperative radiograph showed periapical change of the distal root. Instrumentation of the four root canals was performed by “Balanced Force Technique”. The canals were filled with Diaket sealer and standardized gutta-percha points by “cold lateral condensation technique ”. Radiographs were taken at all stages

Microleakage of Different Root Canal Obturation Techniques

Za ispitivanje propusnosti rabljena je konstrukcija za prijenos tekućine u kojoj se pomakom zračnoga mjehurića mjerila propusnost korijenskih kanala punjenih tehnikama hladne lateralne kondenzacije, Touch\u27n Heat-a i Thermafil tehnike. Kao punilo uz gutaperku se rabio AH Plus i RoekoSeal. Pošto su materijali pohranjeni u fiziološkoj otopini, propusnost se je mjerila nakon mjesec dana, 6 mjeseci i jedne godine. Za svako to ispitivano razdoblje najmanje propuštanje utvrđeno je kod tehnike hladne lateralne kondenzacije, a najveće kod Thermafil tehnike (p<0,05). Znatno veće propuštanje utvrđeno je kod svih ispitivanih uzoraka nakon 12 mjeseci za sve ispitivane tehnike (p<0,05). RoekoSeal i AH Plus podjednako su brtvili kod svake ispitivane tehnike punjenja.Leakage examination was performed using fluid transport system measuring movement of an air bubble. Tested techniques were cold lateral condensation technique, Touch`n Heat and Thermafil technique. Root canals were obturated with gutta-percha in combination with AH Plus and RoekoSeal sealers. After storing in saline solution, microleakage was measured in intervals of one month, six months and one year. The minimum microleakage values were obtained in all intervals in canals obturated using cold lateral condensation technique, while maximum values were obtained in Thermafil technique (p< 0.05). Significantly more leakage was found for all tested techniques in the interval of 12 months after obturation (p< 0.05). There was no difference between obturation quality between RoekoSeal and AH Plus, no matter what obturation technique was used

Between past and future: Social Housing in Serbia in the transitional process

This article discusses the evolution of social public housing in the Yugoslav Federation with reference to Serbia, in relation to a number of socioeconomic- cultural and political variables. The focus on different aspects of the housing problem demonstrates the current challenges and limitations of each of them. The changes that occurred quickly denied the experience of the socialist period, while a reading of the experiences of the past might have been useful to draw interesting suggestions to guide current policies in the sector, which follow the implementation of EU directives in a manner that is uncritical and decontextualised

Zaštita industrijske baštine grada Siska na primjerima Tvorničkog kompleksa Segestice, zgrade Munjare i Starog mosta

Grad Sisak, kao značajno industrijsko središte Hrvatske 20. stoljeća, jedan je od gradova s bogatom industrijskom baštinom. Od Pivovare iz 1855. godine, preko postrojenja starog Shella u krugu „INA Rafinerije”; Tvornice žeste Petra Teslića – današnja „Segestica”; Gradske munjare – prve električne centrale iz 1907. godine, kao i niza drugih građevina, dio su gradskog identiteta. U ovom se radu prezentiraju tri vrlo vrijedna primjera industrijske baštine: tvornički kompleks Segestice, Munjara te Stari most. Izdvojen je dakle primjer tvorničkog kompleksa, pojedinačne građevine i mostogradnje. Upravo se kroz njih prezentira početak rada na revitalizaciji i prenamjeni industrijske baštine grada Siska