METALLIC MATERIALS FOR USE IN DENTISTRY

Dentistry as a branch of medicine has an important role in the health of the human, while applying new technologies the maintaining of oral health is much more effective. For that purpose many dental products are used, such as crowns, bridges, implants, which are made of various metallic materials the mostly by casting or forging. They have to possess an adequate properties among which a biocompatibility, hardness and strength are the most important. Metal as an individual element with its properties does not meet certain conditions, therefore, the process of alloying results in different alloys that may be applied in oral environment. The most common classification of metallic materials for use in dentistry divides them in: noble and non-noble alloys and dental amalgames. Further, development of new technologies provides a new metallic materials with more adequate properties. Among them, titanium and titanium-based alloys stand out as materials of future in dentistry. Also, progress in computer technology results in faster production of economic dental products of much more quality

Utjecaj sastava na strukturu i svojstva Ti-Co-Cr legura

The present work is a study of six as-cast Ti-Co-Cr alloys in the Ti-rich region with the purpose of examining the possibility of obtaining a new β-type Ti-alloys. Two experimental alloys Ti80Co10Cr10 and Ti70Co10Cr20 are nearly single-phases and are identified as bcc β-Ti phase. They also display the lowest hardness values and the best corrosion properties. The present study indicates that the region of biomedically-acceptable ternary Ti-rich alloys is situated within lower concentrations of alloying elements, i.e. about 10 at.% Co and 20 at. % Cr.Istraživanje šest lijevanih Ti-Co-Cr legura u području bogatom s titanom provedeno je s ciljem da se ustanovi mogućnost dobivanja novih β-Ti legura. Dvije eksperimentalne legure Ti80Co10Cr10 i Ti70Co10Cr20 pokazuju skoro jedno-faznu mikrostrukturu, koja je identificirana kao bcc β-Ti faza. One također imaju najniže vrijednosti tvrdoća i najbolja korozijska svojstva. Ovo istraživanje pokazuje, da se područje biomedicinski prihvatljivih ternarnih, titanom bogatih legura nalazi unutar nižih koncentracija legirnih elemenata tj. oko 10 at.% Co i 20 at. % Cr

Usporedba mikrostrukturnih karakteristika biomedicinskih Ti (70,80 AT.%)-Cr-Mo i Ti(70,80 AT.%)-Nb-Zr legura

This paper shows comparison of microstructural characteristics of Ti-Cr-Mo and Ti-Nb-Zr alloys. Purpose of this investigation was to examine the microstructure and hardness of these alloys with potential for biomedical use. Three samples of each alloy type with different composition were laboratory prepared by an arc melting method. Their microstructure was examined by light and scanning electron microscope with EDS. Hardness was determined by Vickers method. Results show that Ti-Cr-Mo alloys have two-phases microstructure containing β and L or L” phase, while Ti-Nb-Zr alloys were nearly β single-phase with traces of L-phase. EDS analysis indicates that L and β have similar chemical composition. Vickers hardness of Ti-Cr-Mo alloys increases with molybdenum content, while those for Ti-Nb-Zr alloys increases with niobium content. According to the closely single-phase microstructure and lower hardness, Ti-Nb-Zr alloys have adventage as potential biomedical materials.Ovaj rad prikazuje usporedbu mikrostrukturnih karakteristika Ti-Cr-Mo i Ti-Nb-Zr legura. Svrha rada bila je ispitati mikrostrukturu i tvrdoću navedenih legura za potencijalnu primjenu u biomedicini. Od svake skupine legura laboratorijski su pripremljena po tri uzorka različitog sastava u lučnoj peći. Njihova mikrostruktura je ispitana svjetlosnim i skenirajućim elektronskim mikroskopom s energijsko-disperzivnim spektrometrom. Tvrdoća je određena Vickersovom metodom. Rezultati pokazuju da su Ti-Cr-Mo legure dvofazne, odnosno da sadrže β i L ili L“ fazu, dok su Ti-Nb-Zr legure uglavnom β-jednofazne s L-fazom u tragovima. EDS analiza je pokazala da L (L“) i β faze imaju vrlo sličan kemijski sastav. Tvrdoća prema Vickersu Ti-Cr-Mo legura povećava se s udjelom molibdena u leguri, dok se ona za Ti-Nb-Zr legure povećava s udjelom niobija. Zbog skoro β-jednofazne mikrostrukture i niže tvrdoće u odnosu na Ti-Cr-Mo legure, Ti-Nb-Zr legure imaju veći potencijal za primjenu kao biomedicinski materijali

Utjecaj sastava na strukturu i svojstva Ti-Co-Cr legura

The present work is a study of six as-cast Ti-Co-Cr alloys in the Ti-rich region with the purpose of examining the possibility of obtaining a new β-type Ti-alloys. Two experimental alloys Ti80Co10Cr10 and Ti70Co10Cr20 are nearly single-phases and are identified as bcc β-Ti phase. They also display the lowest hardness values and the best corrosion properties. The present study indicates that the region of biomedically-acceptable ternary Ti-rich alloys is situated within lower concentrations of alloying elements, i.e. about 10 at.% Co and 20 at. % Cr.Istraživanje šest lijevanih Ti-Co-Cr legura u području bogatom s titanom provedeno je s ciljem da se ustanovi mogućnost dobivanja novih β-Ti legura. Dvije eksperimentalne legure Ti80Co10Cr10 i Ti70Co10Cr20 pokazuju skoro jedno-faznu mikrostrukturu, koja je identificirana kao bcc β-Ti faza. One također imaju najniže vrijednosti tvrdoća i najbolja korozijska svojstva. Ovo istraživanje pokazuje, da se područje biomedicinski prihvatljivih ternarnih, titanom bogatih legura nalazi unutar nižih koncentracija legirnih elemenata tj. oko 10 at.% Co i 20 at. % Cr

COMPARISON OF CONCESSION AND LICENSING SYSTEM FOR PROVIDING CHIMNEY SWEEPING SERVICES

Dimnikarske storitve se v državah članicah EU izvajajo na različne načine in v različnih organizacijskih oblikah, kot gospodarske storitve splošnega pomena, kot koncesionirane javne službe, ali kot delno ali povsem liberalizirane storitve na notranjem trgu Evropske unije. Tako kot za vse ostale storitve, tudi za dimnikarske storitve namreč velja, da se morajo na notranjem trgu EU izvajati v skladu s pravili zagotavljanja prostega trga in konkurenčnosti, če jim ta pravila ne preprečujejo izvajanja posebnih obveznosti za doseganje ciljev v javnem interesu. Magistrsko delo obravnava problem liberalizacije trga dimnikarskih storitev v skladu s pravili konkurenčnosti na notranjem trgu EU ter analizira koncesijski in licenčni sistem izvajanja teh storitev v Sloveniji in v nekaterih drugih državah EU glede skladnosti s temeljnimi načeli in pravili prava EU, predvsem z vidika enakosti in nediskriminacije, preglednosti in sorazmernosti, zasledovanja javnega interesa varstva okolja, zdravja ljudi in ogrožanja varnosti ter varstva pred požarom. V obeh sistemih analizira, primerja in ocenjuje stopnjo zaščite javnega interesa in zagotavljanje konkurenčnosti storitev ter vrste, vsebine in obseg neposrednega inšpekcijskega nadzora nad izvajalci in uporabniki dimnikarskih storitev. V magistrskem delu so izpostavljene tri ključne ugotovitve. Koncesijski sistem izvajanja dimnikarskih storitev je lahko v neskladju s temeljnimi načeli in pravili prava EU. Licenčni sistem izvajanja dimnikarskih storitev, ki temelji le na pravno regulirani liberalizaciji trga storitev, ne zagotavlja tudi zaščite javnega interesa varstva okolja, varstva zdravja in požarne varnosti. Licenčni sistem izvajanja dimnikarskih storitev v primerjavi s koncesijskim sistemom znatno povečuje obseg neposrednega upravnega in inšpekcijskega nadzora izvajalcev dimnikarskih storitev in uporabnikov malih kurilnih naprav.In the EU Member States chimney sweeping services are provided in different ways and in various organisational forms, as services of general economic interest, as public service concessions, or as partly or completely liberalized services on the internal market of the European Union. On the internal market of the EU chimney sweeping services, as all other services, have to be implemented in accordance with the rules, ensuring free market and competitiveness, in so far as the application of such rules does not obstruct the performance of the particular tasks assigned to them to achieve specific objectives in the general public interest. The master thesis deals with the problem of liberalization of the chimney sweeping services in accordance with the rules of competitiveness on the EU internal market and analyses the implementation of the concession and the licensing system of these services in Slovenia and in some other EU countries regarding compliance with the fundamental principles and rules of EU law in particular in terms of equality and non-discrimination, transparency and proportionality, pursuing public interest for protecting the environment, human health and fire safety. In both systems, it analyses, compares and assesses the level of protection of public interest, competitiveness of these services, as well as the content and the scope of direct inspection of chimney sweeping service providers and users. Three main findings are highlighted in the master\u27s thesis. The concession system for the provision of the chimney sweeping services may be inconsistent with the fundamental principles and the rules of EU law. The licensing system for the provision of chimney sweeping services, based solely on the legally regulated liberalization of the service market, does not guarantee protection of the public interest for protecting the environment, human health and fire safety. The implementation of licensing system for the provision of chimney sweeping services in comparison with the concession system significantly increases the scope of direct administrative and inspection supervision of the chimney-sweeping providers and the users of small combustion installations

EFFECT OF HARD METAL PRODUCTION ON THE ENVIRONMENT

This paper deals with production of hard metal by powder metallurgy and its effect on the environment. Hard metal is a composite material that consists of tungsten carbide as the hard refractory phase and cobalt or nickel as the soft metal binder phase. It cannot be produced by classical casting technology. Owing to its excellent properties, such as high hardness, wear and heat resistance etc., hard metal can be applied in a variety of industrial fields. Powder metallurgy is a technology for production of a wide range of materials as net-shape products from a compacted and sintered powders mixture. In this paper the impact of all stages of hard metal production by powder metallurgy on the environment is analysed. The presented analysis shows that production of hard metal by powder metallurgy has a minimum effect on the environment

Sulfonylureas in type 2 diabetes mellitus: current evidence, conflicts and clinical implications

Introduction: We sought to explore the current state of evidence on sulfonylurea therapy in type 2 diabetes mellitus (T2DM) and critically examine the recommendations of major practice guidelines,and the overall ramifications of the issues thereof in current clinical practice.Method: We searched PUBMED, MEDLINE and other databases, and selected, analysed and interpreted relevant original studies,reports and reviews on the subject.Results: A compelling body of literature exist on the sulfonylurea use in T2DM, with a remarkable number of studies illuminating substantial clinical issues associated with their use. Nevertheless, definitive evidence is still limited in terms of unequivocally clarifying some of the concerns. All major practice guidelines mirrored a historical trend of consistent endorsement of sulfonylureas as first or second line agents in T2DM management. However, based on re-evaluation of available evidence, some latest guidelines have reflected a significantly declined confidence in the traditional status accorded to sulfonylureas in T2DM management, conspicuously contrasting other existing guidelines.Conclusion: The apparent inconsistencies and deficiencies in the available body of evidence and the conflicting recommendations in current guidelines have raised new questions and complicated clinical considerations, creating a novel dilemma in the clinical use of sulfonylureas.Keywords: Sulfonylurea; type 2 diabetes mellitus; evidence;guidelines; clinical practic

Human Endogenous Retroviruses as Pathogenic Factors in the Development of Schizophrenia.

Schizophrenia is a complex disorder, characterized by the interplay between genetic and environmental factors. Human endogenous retroviruses (HERVs), genetic elements that originated from infections by exogenous retroviruses millions of years ago, comprise ~8% of the human genome. Here, we provide a comprehensive review of accumulating evidence, detailing HERV aberrancies associated with schizophrenia. Studies examining the genome, transcriptome, and proteome of individuals with schizophrenia provide data that support the association of these viral elements with the disorder. Molecular differences can be found within the central nervous system and peripheral tissues. However, additional studies are needed to substantiate the reported link and to address several discrepancies among previous investigations. We further discuss potentially relevant pathogenic mechanisms to the development of schizophrenia