Preparation of Electrically Fused Magnesium Oxide from Calcined Magnesite for Use in Electrothermics

U današnje vrijeme postoji velika potreba za materijalima koji mogu podnijeti oksidacijske uvjete na vrlo visokim temperaturama. Pogodan materijal za takvu primjenu je elektrolučno taljeni magnezijev oksid (MgO), s talištem 2825 °C, koji je od velike važnosti za proizvodnju visoko vatrostalnih materijala. Kristali MgO dobiveni iz taline pravilnije su građe, s manje strukturnih pogrešaka u usporedbi s kristalima koji nastaju sinteriranjem na nižim temperaturama. Cilj rada priprava je vrlo čistog elektrolučno taljenog MgO iz kalciniranog magnezita za uporabu u elektrotermiji. U istraživanjima su upotrijebljeni uzorci magnezita (MgCO3) iz ležišta Strezovce, Kosovo, za pripravu vrlo čistog MgO taljenog u peći za elektrolučno taljenje u Kosovskoj Kamenici. Nakon priprave granuliranog taljenog MgO, pri čemu su kontrolirani atmosfera, temperatura i trajanje obrade, određeni su parametri optimalne toplinske obrade i mikrotvrdoća. Na temelju izvedenih istraživanja može se zaključiti da je, uz optimalne uvjete u svim fazama postupka, iz kalciniranog magnezita ležišta Strezovce moguća priprava taljenog MgO za primjenu u elektrotermiji, koji je kvalitetom usporediv s MgO dostupnim na svjetskom tržištu.Nowadays, there is a great need for materials that can withstand oxidative environment at very high temperatures. The most important material for such use is electrically fused MgO with melting point 3098 K and of great importance in the production of high-heat-resistant materials. MgO crystals obtained from melt have a regular structure, with few structural faults, compared to MgO crystals, which are formed at lower temperatures by sintering process. The goal of this work is the preparation of pure electrically fused MgO for use in electrothermics, from calcinated magnesite. Because the Republic of Kosovo possesses grade magnesite (MgCO3), in this research for preparation of pure fused MgO in the electromelting furnace in Kosovska Kamenica samples of Strezovce magnesite deposit were used. After granulated fused MgO preparation, the optimum heat treatment and hardness were determined under controlled atmosphere, temperature range, and total time. Based on the research presented in this paper, it can be concluded that under optimal conditions at all stages, from calcined magnesite deposits of Strezovce, Republic of Kosovo, possible is the preparation of fused MgO for use in electrothermics, of quality comparable to MgO, which is available on the world market

Preparation of Highly Pure Aluminium Oxide (α-Al2O3) Ceramic for Extrusion Moulding

S obzirom na izuzetno široku primjenu aluminijev oksid (Al2O3) najvažniji je materijal iz skupine oksidne keramike. Najvažnija svojstva aluminij-oksidne keramike visoka su čvrstoća i tvrdoća, temperaturna stabilnost, velika otpornost na abraziju, otpornost prema djelovanju agresivne okoline (osim ograničene otpornosti prema lužinama) i korozijska postojanost pri povišenim temperaturama. Zbog navedenih svojstava aluminij-oksidna keramika primjenjuje se u sljedećim područjima: industriji sanitarija za brtvene elemente, elektrotehnici za izolacijske dijelove, proizvodnji elektroničkih podloga, strojogradnji i graditeljstvu za dijelove otporne na trošenje, kemijskoj industriji za dijelove otporne na koroziju, visoke temperature, paru, taline i trosku, mjernoj tehnici za zaštitne cijevi termoelemenata za mjerenja pri visokim temperaturama, medicini za implantate te za visokotemperaturnu primjenu poput sapnica za plamenike te nosače grijača. U radu je opisano dobivanje aluminij-oksidne (α-Al2O3) keramike visoke čistoće za oblikovanje ekstrudiranjem, kvalitetom usporedive s uzorcima dostupnim na svjetskom tržištu. Proizvodnja obuhvaća sljedeće postupke: dobivanje α-Al2O3, pripravu keramičkog praha, pripravu keramičke mase, ekstrudiranje, sušenje, sinteriranje i ispitivanja proizvoda.Aluminium oxide (A2O3) is the most important material from the group of oxide ceramics due to the extremely wide range of applications. The most important properties of aluminium oxide ceramics are high strength and hardness, temperature stability, high resistance to abrasion, resistance to aggressive work environment (except limited alkali resistance) and corrosion resistance at elevated temperatures. Due to these properties, aluminium oxide is used in the following areas: sanitation industry for sealing elements, electrical insulating parts, electronics substrates, engineering and construction of wear resistant parts, chemical industry for parts that are corrosion, high-temperature steam, and molten slag resistant, thermocouple measurements at high temperatures, medical implants and high temperature applications, such as nozzle and heater mounts. This paper describes the process of preparation of highly pure aluminium oxide (α-Al2O3) ceramics for extrusion moulding, quality comparable to the world market. The production includes the following operations: obtaining α-Al2O3, preparation of ceramic powders, preparation of ceramic mass, extruding, drying, sintering, product testing

Equilibria-based Probabilistic Model Checking for Concurrent Stochastic Games

Probabilistic model checking for stochastic games enables formal verification of systems that comprise competing or collaborating entities operating in a stochastic environment. Despite good progress in the area, existing approaches focus on zero-sum goals and cannot reason about scenarios where entities are endowed with different objectives. In this paper, we propose probabilistic model checking techniques for concurrent stochastic games based on Nash equilibria. We extend the temporal logic rPATL (probabilistic alternating-time temporal logic with rewards) to allow reasoning about players with distinct quantitative goals, which capture either the probability of an event occurring or a reward measure. We present algorithms to synthesise strategies that are subgame perfect social welfare optimal Nash equilibria, i.e., where there is no incentive for any players to unilaterally change their strategy in any state of the game, whilst the combined probabilities or rewards are maximised. We implement our techniques in the PRISM-games tool and apply them to several case studies, including network protocols and robot navigation, showing the benefits compared to existing approaches

Widest Paths and Global Propagation in Bounded Value Iteration for Stochastic Games

Solving stochastic games with the reachability objective is a fundamental problem, especially in quantitative verification and synthesis. For this purpose, bounded value iteration (BVI) attracts attention as an efficient iterative method. However, BVI's performance is often impeded by costly end component (EC) computation that is needed to ensure convergence. Our contribution is a novel BVI algorithm that conducts, in addition to local propagation by the Bellman update that is typical of BVI, global propagation of upper bounds that is not hindered by ECs. To conduct global propagation in a computationally tractable manner, we construct a weighted graph and solve the widest path problem in it. Our experiments show the algorithm's performance advantage over the previous BVI algorithms that rely on EC computation.Comment: v2: an URL to the implementation is adde

An unusual location of retroperitoneal epidermoid cyst in a child: case report and a review of the literature

We report the case of a 4-year-old girl presenting with the retroperitoneal epidermoid cyst. The lesion presented as an intra-abdominal cyst on physical examination and was followed up with more specific investigations by ultrasound and computed tomographic scanning. The final diagnosis was obtained only after laparotomy where the cystic mass was completely excised and pathological examination was done. The patient is well at 3-year follow-up. epidermoid cyst of the reteroperitoneal space, although rare, should be considered in the differential diagnosis of incidentally discovered intra-abdominal cysts during investigation of irrelevant illnesses or during routine abdominal ultrasound scan

Equilibria-based probabilistic model checking for concurrent stochastic games

Probabilistic model checking for stochastic games enables formal verification of systems that comprise competing or collaborating entities operating in a stochastic environment. Despite good progress in the area, existing approaches focus on zero-sum goals and cannot reason about scenarios where entities are endowed with different objectives. In this paper, we propose probabilistic model checking techniques for concurrent stochastic games based on Nash equilibria. We extend the temporal logic rPATL (probabilistic alternating-time temporal logic with rewards) to allow reasoning about players with distinct quantitative goals, which capture either the probability of an event occurring or a reward measure. We present algorithms to synthesise strategies that are subgame perfect social welfare optimal Nash equilibria, i.e., where there is no incentive for any players to unilaterally change their strategy in any state of the game, whilst the combined probabilities or rewards are maximised. We implement our techniques in the PRISM-games tool and apply them to several case studies, including network protocols and robot navigation, showing the benefits compared to existing approaches

Association of polymorphisms in HCN4 with mood disorders and obsessive compulsive disorder

Hyperpolarization activated cyclic nucleotide-gated (HCN) potassium channels are implicated in the control of neuronal excitability and are expressed widely in the brain. HCN4 is expressed in brain regions relevant to mood and anxiety disorders including specific thalamic nuclei, the basolateral amygdala, and the midbrain dopamine system. We therefore examined the association of HCN4 with a group of mood and anxiety disorders. We genotyped nine tag SNPs in the HCN4 gene using Sequenom iPLEX Gold technology in 285 Caucasian patients with DSM-IV mood disorders and/or obsessive compulsive disorder and 384 Caucasian controls. HCN4 polymorphisms were analyzed using single marker and haplotype-based association methods. Three SNPs showed nominal association in our population (rs12905211, rs3859014, rs498005). SNP rs12905211 maintained significance after Bonferroni correction, with allele T and haplotype CTC overrepresented in cases. These findings suggest HCN4 as a genetic susceptibility factor for mood and anxiety disorders; however, these results will require replication using a larger sample

Gendered self-views across 62 countries: a test of competing models

Social role theory posits that binary gender gaps in agency and communion should be larger in less egalitarian countries, reflecting these countries’ more pronounced sex-based power divisions. Conversely, evolutionary and self-construal theorists suggest that gender gaps in agency and communion should be larger in more egalitarian countries, reflecting the greater autonomy support and flexible self-construction processes present in these countries. Using data from 62 countries (N = 28,640), we examine binary gender gaps in agentic and communal self-views as a function of country-level objective gender equality (the Global Gender Gap Index) and subjective distributions of social power (the Power Distance Index). Findings show that in more egalitarian countries, gender gaps in agency are smaller and gender gaps in communality are larger. These patterns are driven primarily by cross-country differences in men’s self-views and by the Power Distance Index (PDI) more robustly than the Global Gender Gap Index (GGGI). We consider possible causes and implications of these findings

Gender gap in parental leave intentions: Evidence from 37 countries

This is the final version. Available from Wiley via the DOI in this record. Despite global commitments and efforts, a gender-based division of paid and unpaid work persists. To identify how psychological factors, national policies, and the broader sociocultural context contribute to this inequality, we assessed parental-leave intentions in young adults (18–30years old) planning to have children (N = 13,942; 8,880 identified as women; 5,062 identified as men) across 37 countries that varied in parental-leave policies and societal gender equality. In all countries, women intended to take longer leave than men. National parental-leave policies and women’s political representation partially explained cross-national variations in the gender gap. Gender gaps in leave intentions were paradoxically larger in countries with more gender-egalitarian parental-leave policies (i.e., longer leave available to both fathers and mothers). Interestingly, this cross-national variation in the gender gap was driven by cross-national variations in women’s (rather than men’s) leave intentions. Financially generous leave and gender-egalitarian policies (linked to men’s higher uptake in prior research) were not associated with leave intentions in men. Rather, men’s leave intentions were related to their individual gender attitudes. Leave intentions were inversely related to career ambitions. The potential for existing policies to foster gender equality in paid and unpaid work is discussed.SSHRC Insight Development GrantSSHRC Insight GrantEconomic and Social Research CouncilState Research AgencyGuangdong 13th-five Philosophy and Social Science Planning ProjectNational Natural Science Foundation of ChinaSwiss National Science FoundationSwiss National Science FoundationCenter for Social Conflict and Cohesion StudiesCenter for Intercultural and Indigenous ResearchSSHRC Postdoctoral FellowshipSlovak Research and Development AgencySwiss National Science FoundationCanada Research ChairsSocial Sciences and Humanities Research Council of CanadaOntario Ministry of Research and InnovationHSE University, RFFaculty of Arts, Masaryk Universit