Konstrukcija rješenja planetarnog prijenosnika

U radu je prikazano konstrukcijsko rješenje planetarnog prijenosnika. Kako prijenosni omjer nije značajno velik, odlučeno je da se prijenosnik izvede kao prijenosnik jednostupanjski i to 1UV tipa. U početku rada je objašnjen princip sklapanja planetarnog prijenosnika, te je dan prikaz nekih njegovih varijanti. Spomenute su prednosti i nedostaci planetarnih prijenosnika koje imaju značajnu ulogu u samom procesu konstrukcije te je objašnjen način označavanja planetarnih prijenosnika. U kinematskoj analizi je dan prikaz gibanja članova prijenosnika u odnosu na okolinu i u odnosu na druge članove, a provjereni su i kriteriji koje jedan planetarni prijenosnik mora ostvarivati: kriterij koaksijalnosti, susjednosti i sprezanja. Zatim je izvršen proračun čvrstoće zupčanika, proračun čvrstoće vratila i odabir ležajeva na koja su vratila oslonjena. Na osnovu izvršenog proračuna je izrađen model planetarnog prijenosnika i njegova tehnička dokumentacija

Performance Evaluation of Virtualization Tools in Multi-Threaded Applications

In the last decade, virtualization technologies have become very popular. Virtualization enables a user to run multiple operating systems on the same computer concurrently, while providing a degree of isolation between OS instances. Even though virtualization is mostly used on servers, its popularity on desktop also rises, where it is mostly used in cross-platform development and execution of software available to other platforms. Since both of these use cases are performance intensive, the goal of this paper is to evaluate the performance of a couple of the most popular desktop virtualization tools on the market, i.e., VMWare Player and Oracle VirtualBox. Benchmarks used in this paper evaluate the performance of the tools in both CPU intensive and GPU intensive applications, with special emphasis placed on the performance of multi-threaded applications

Masonry columns behaviour analyses due to a different mode of confinement with GFRP straps

The paper describes the experimental research of masonry columns behavior under the load of vertical compression. A total of thirty-four specimens were tested: three unconfined specimens and thirty-one specimens confined with GFRP straps. In addition to the load-bearing efficiency analysis of confined columns in relation to the number of the confinement layers, the intention of these tests was to determine the efficiency of spiral confinement in relation to conventional confinement. The impact of the existing compressive stress in a column during confinement to the final increased load-bearing capacity of the confined column was also studied.. The test results have shown that all of the confined specimens have a greater load-bearing capacity and ductility than the unconfined specimens. The results of spiral confinement were almost identical to the results of conventional confinement, which is vital considering that spiral confinement is easier to perform. The results of the test lead to the conclusion that the presence of compressive stress in a column during confinement does not significantly reduce confinement efficiency. This makes it possible to effectively increase the bearing capacity of masonry columns without the need to previously unload the structure, while the structure is in service. The paper also provides expressions for the estimated increase in the compressive strength of confined columns that well correspond to the testing results

EVALUATION OF RESEARCH IN BAUXITE-BEARING AREA ON A LOCALITY „CRVENE STIJENE“ WITH EMPHASIS ON EXPLOITATION OF ASSOCIATED DEPOSITS

In this paper we present and elaborate one example when bauxite was the main target of investigation. During reprocessing and reinterpreting original input data from locality “Crvene stijene” near Jajce in Bosnia and Herzegovina, it was established that bauxite hanging wall and footwall rocks in fact present even more valuable mineral resources, dimension stone. This paper presents results of reprocessing and reinterpretation of original data with focus not only on primary resource, but on resources that are developed in footwall and hanging wall. Final goal of the research was to optimize the ratio between research and exploration cost and total profit by exploration of all available mineral resources in the area. For that purpose, new method of bauxite (primary resource) and associated deposits is developed and named “integrated approach”. Integrated, joint evaluation of bauxite and associated deposits (dimension stone), would give far greater significance to whole area. Finally, with this new method, the ratio between overall profit and cost will be maximized. </p

Procjena in vitro toksičnosti stakleno-ionomernih cemenata primjenom mikronukleus testa, alkalnog komet testa i komet testa modificiranog hOGG1 enzimom

The purpose of this study was to evaluate the genotoxic potential of components leached from two conventional self-curing glass-ionomer cements (Fuji IX and Ketac Molar), and light-curing, resin modified glass-ionomer cements (Vitrebond, Fuji II LC). Evaluation was performed on human lymphocytes using alkaline and hOGG1 modified comet, and micronucleus assays. Each material, polymerised and unpolymerised, was eluted in extracellular saline (1 cm2 mL-1) for 1 h, 1 day, and 5 days. Cultures were treated with eluates using final dilutions of 10-2, 10-3, and 10-4. Alkaline comet assay did not detect changes in DNA migration of treated cells regardless of the ionomer tested, polymerisation state, and elution duration. Glass ionomers failed to significantly influence micronucleus frequency. No oxidative DNA damage in treated lymphocytes was observed using hOGG1 modified comet assay. Obtained results indicate high biocompatibility of all tested materials used in the study under experimental conditions.Svrha istraživanja bila je procijeniti genotoksični potencijal komponenata koje izlučuju dva konvencionalna samopolimerizirajuća stakleno-ionomerna cementa (Fuji IX i Ketac Molar) te svjetlosno polimerizirajući i smolom modificirani stakleno-ionomerni cementi (Vitrebond, Fuji II LC). Istraživanje je provedeno na ljudskim limfocitima primjenom alkalnog komet testa, komet testa modificiranog hOGG1 enzimom te mikronukleus testa. Svaki materijal, polimerizirani i nepolimerizirani, eluiran je u fiziološkoj otopini (1 cm2 mL-1) tijekom jednog sata, jednog dana i tijekom 5 dana. Kulture limfocita tretirane su eluatima u razrjeđenjima 10-2, 10-3 i 10-4. Alkalnim komet testom nisu zabilježene promjene u migraciji DNA iz tretiranih stanica bez obzira na ispitani ionomer, vrstu polimerizacije i trajanje elucije. Izloženost staklenim ionomerima nije značajno utjecala na učestalost mikronukleusa. Primjenom hOGG1 modificiranog komet testa nije zamijećeno oksidativno oštećenje DNA u tretiranim limfocitima. Dobiveni rezultati upućuju na visoki stupanj biokompatibilnosti svih testiranih materijala koji su se koristili u eksperimentalnim uvjetima

Procjena anksioznosti i njezina korist u oralnoj kirurgiji s lokalnom anestezijom kod pacijenata koji se podvrgavaju četirima operativnim zahvatima

Introduction: Fear of intervention in the oral cavity is declared as dental fear and is defined as a specific form of anxiety. The reaction to oral-surgical intervention will also depend on the feeling the patient acquires about the operator, but the positive experience also plays an important role. Aim: The aim is to evaluate differences between the sexes and the influence of experience from a previous oral surgical intervention on a similar subsequent intervention. Material and methods: In the research, anxiety was assessed using Corah\u27s Dental Anxiety Scale (DASR) and Spielberger\u27s State-Trait Anxiety Inventory (X1 and X2). The study included adult patients of both sexes with an indication for surgical extraction of impacted third permanent molars. Preoperative and postoperative anxiety was assessed: 1st measurement (day of examination) - DASR, and STAI (X1 and X2); 2nd measurement (immediately before the intervention) – STAI (X1 and X2); 3rd measurement (day after the intervention) – STAI (X1 and X2). Results: Preoperatively determined high levels of general, immediate, and dental anxiety decreased before the surgical procedure itself and were significantly reduced in the postoperative period. The downward trend continued in line with the positive experience. Women had higher anxiety scores than men for all monitored parameters. The use of the STAI scales to assess anxiety by dental practitioners is on par with other well-known anxiety assessment instruments, such as the DASR. Conclusion: In order to increase patient satisfaction and to prevent possible complications in such oral-surgical procedures, it would be useful to consider adequate therapy for high anxiety.Uvod: Strah od intervencije u usnoj šupljini naziva se dentalni strah i definira se kao specifičan oblik anksioznosti. Reakcija na oralno-kiruršku intervenciju također će ovisiti o osjećaju koji pacijent stječe o operateru, ali i pozitivno iskustvo ima važnu ulogu. Cilj: Procijenjene su razlike između spolova i utjecaj prethodnog iskustva s oralno-kirurškom intervencijom na sličnu naknadnu intervenciju. Materijali i metode: U istraživanju su sudjelovali odrasli pacijenti oba spola s indikacijom za kirurško vađenje impaktiranih trećih trajnih molara. U istraživanju je anksioznost procijenjena korištenjem Corahove ljestvice dentalnog straha (DASR) i Spielbergerovog inventara anksioznosti stanja-i-trenutka (X1 i X2). Procijenjena je anksioznost prije i poslije operacije: 1. mjerenje (dan pregleda) - DASR i STAI (X1 i X2); 2. mjerenje (odmah prije intervencije) - STAI (X1 i X2); 3. mjerenje (dan nakon intervencije) - STAI (X1 i X2). Rezultati: Preoperativno utvrđene visoke razine opće, trenutne i dentalne anksioznosti smanjile su se prije same kirurške procedure i značajno su se smanjile u postoperativnom razdoblju. Silazni trend nastavio se u skladu s pozitivnim iskustvom. Žene su imale više bodova anksioznosti od muškaraca za sve praćene parametre. Upotreba STAI ljestvica za procjenu anksioznosti kojom se koriste stomatološki stručnjaci na istoj je razini s drugim poznatim instrumentima za procjenu anksioznosti, poput DASR-a. Zaključak: Da bi se povećalo zadovoljstvo pacijenta i spriječile moguće komplikacije u takvim oralno-kirurškim postupcima, korisno bi bilo razmotriti adekvatnu terapiju za visoku anksioznost

Profesionalni zdravstveni rizici u suvremenoj stomatologiji

Occupational diseases are diseases or health disorders that are caused by the work or working conditions. There are also work related diseases which usually have multifactorial origin. Occupational health hazard can be defined as a risk to a person usually arising out of employment in sense of the nature or working conditions of a particular job. Occupational hazards in dental medicine can be grouped as biological, biomechanical, chemical, physical and psychological. The aim of this paper is to provide a brief overview of the most important occupational health hazards in contemporary dentistry and to present the prevention activities at the School of Dental Medicine University of Zagreb regarding occupational diseases among dental students and dental practitioners.Profesionalne bolesti su bolesti ili zdravstveni poremećaji uzrokovani radom ili radnim uvjetima. Osim toga, postoje i bolesti vezane uz rad koje imaju višeuzročno podrijetlo. Profesionalni zdravstveni rizici se mogu definirati kao rizici koji se javljaju kod određenog zanimanja s obzirom na radne uvjete pojedinog radnog mjesta. Profesionalne opasnosti u stomatologiji se mogu podijeliti na biološke, biomehaničke, kemijske, fizikalne i psihološke. Svrha ovog rada je pružiti pregled najvažnijih profesionalnih zdravstvenih opasnosti u suvremenoj stomatologiji i predstaviti aktivnosti na Stomatološkom fakultetu Sveučilišta u Zagrebu s obzirom na prevenciju profesionalnih bolesti među studentima stomatologije i stomatolozima

Education on Occupational Health and Health Related Habits among Dental Students in Croatia

Uvod: Profesionalne bolesti su bolesti uzrokovane štetnim utjecajem radnoga mjesta, a bolesti vezane uz rad uzrokovane su mnogim čimbenicima, pri čemu su štetni radni uvjeti jedan od mogućih. Stomatologija je profesija s visokim rizikom od pojave profesionalnih bolesti. Svrha ovog rada je predstaviti rezultate ankete o profesionalnim bolestima i zdravstvenim navikama koja je provedena među studentima Stomatološkog fakulteta Sveučilišta u Zagrebu, te pokazati kako je poboljšala obrazovanje uvođenjem novog kolegija u nastavni plan. Ispitanici i metode: Studentima svih godina na Stomatološkom fakultetu Sveučilišta u Zagrebu (ukupno 663) bilo je ponuđeno sudjelovanje u anketi o profesionalnim bolestima i zdravstvenim navikama. Rezultati: Upitnik je ispunio 351 student – 28 posto studenata i 22,5 posto studentica su pušači. Tijekom prve dvije godine studija čak njih 84,6 posto konzumira alkohol najmanje jedanput na tjedan. Prije počeka studija 84,6 posto studenata i 77,6 posto studentica bavilo se sportom. Znatan pad broja studenata i studentica koji se bave sportom uočen je na prvoj godini studija. Svjesnost o zdravstvenim rizicima u stomatološkoj profesiji raste s godinom studija. Većina studenata smatra da profesionalne bolesti mogu biti spriječene. Zaključak: Rezultati su pokazali da studenti upisuju dentalnu medicinu s razmjerno niskim znanjem o zdravstvenim opasnostima koje se pojavljuju u stomatološkoj profesiji. Iako razina znanja i svijesti raste s godinom studija, štetne navike kao što su pušenje, konzumiranje alkoholnih pića i nedostatak fizičke aktivnosti prisutne su i u višim godinama studija.Introduction: Occupational diseases are diseases caused by occupational exposures at the workplace, while diseases related to work are diseases caused by many factors, wherein the harmful work conditions are one of the possible causes. Dental medicine is a profession with a high risk of developing occupational diseases. The aim of this paper was to present the results of a survey about occupational health risks and health related habits among dental students at the School of Dental Medicine University of Zagreb and to show how this survey led to an improvement in education by introducing a new course into the dental curriculum. Participants and methods: Students of all years at the School of Dental Medicine University of Zagreb (total of 663) were offered to participate in a survey about occupational health risks and health related habits. Results: A questionnaire was completed by 351 students. 28.0% of male students and 22.5% of female students were smokers. During the first two years of study, up to 84.6% of students consumed alcoholic beverages at least once a week. Prior to enrollment in the university, 85.3% male and 77.6% female students were engaged in sports. The significant drop in the number of students who participated in sports was noticed in the first study year in both sexes. Student awareness of the health risks related to dental profession increases with the year of study. Most students believe that occupational diseases can be prevented. Conclusion: The results have shown that students enter the School of Dental Medicine with a relatively low level of awareness of the health hazards of dental profession. Although the level of awareness increases with years of study, harmful habits such as smoking, alcohol consumption, and the lack of physical activity also remain present in the later years of study