Altering Occlusal Vertical Dimension Provisionally with Base Metal Onlays: A Clinical Report

This article presents a method for altering occlusal vertical dimension (OVD) to restore dentitions with limited restorative space due to loss of tooth structure. A provisional increase in OVD is achieved using predominately base metal onlays, which offer advantages over conventional techniques. The onlays are resistant to wear, may be bonded well to nonrestored and restored tooth surfaces with resin cements, and provide a fairly reversible method of increasing OVD. A patient situation is presented which demonstrates the use of provisional base metal onlays in complete mouth rehabilitation

Determination of fire and explosion characteristics of dust

The aim of this paper is to approximate danger of dust clouds normally occur by determining their explosion characteristics. Nowadays, dusty environment is phenomenon in the industry. In general, about 70% of dust produced is explosive. Dust reduction in companies is the main purpose of the national and European legislative. Early identification and characterization of dust in companies may reduce the risk of explosion. It could be used to identify hazards in industrial production where an explosive dust is produced. For this purpose several standards for identification and characterization of explosion characteristics of industrial dust are being used

Determination of the Minimum Ignition Temperature of Ground Sweet Pepper Produced by the Food Industry

The current article deals with the determination of fire parameters of ground sweet pepper (GSP) dust cloud. The minimum ignition temperature was determined in accordance with STN EN ISO/IEC 80079-20-2:2016 Standard Explosive atmospheres - Part 20-2, using a Godbert-Greenwald furnace apparatus with various dust concentrations, particle sizes, and dust-dispersion-air pressure (10 kPa, 30 kPa and 50 kPa). Three set of different particle size ranges of GSP powder were tested during the experiment, that is, 90 to<150 μm, 150 to<200 μm, 200 to<250 μm. The MIT depends on the particle size and varied by a maximum of 30 K, and values for the individual samples of GSP was in the range 550 - 610 °C. Minimum ignition temperature of the GSP powder was 550 °C (90 to<150 μm, 0.5 g and 50 kPa)

Influence of the pyrotechnic igniter composition aging on explosion parameters of dispersed dusts

A commercially available pyrotechnic igniter was used according to the EN 14034 and ASTM E1226a Standards to study the explosiveness of dispersed dusts. Its pyrotechnic composition consists of 1.2 g of zirconium (40% wt.), barium peroxide (30% wt.) and barium nitrate (30% wt.). The energy released during the combustion of that amount of composition is 5 kJ. The article investigates the influence of aging of the pyrotechnic composition in the igniter on its initiation parameters. In the study, igniters of different years from date of manufacture were used: Igniter 1, manufactured in 2021 (less than 1 year from date of manufacture), and Igniter 2 (more than 2 years from date of manufacture). The study was performed in the KV 150M2 explosion chamber with a volume of 365 L and the 20 L sphere chamber with a volume of 20 L. A standard sample of Lycopodium clavatum was used in the KV 150M2 explosion chamber. Magnesium and benzoic acid were used as the samples in the 20 L sphere explosion chamber. The experiment showed that the explosion pressure P-max of the igniter with more than 2 years from date of manufacture decreased by up to 10%, while the value of the explosion constant K-st decreased by up to 40%. The attained results proved that aging of igniters affects their explosion parameters and measurement accuracy.Web of Science1122art. no. 1072

Study into the fire and explosion characteristics of polymer powders used in engineering production technologies

Polymers and their processing by engineering production technologies (injection, molding or additive manufacturing) are increasingly being used. Polymers used in engineering production technologies are constantly being developed and their properties are being improved. Granulometry, X-ray, FTIR and TGA were used to characterize polymer samples. Determination of the fire parameters of powder samples of polyamide (PA) 12, polypropylene, and ultra-high molecular weight (UHMW) polyethylene is the subject of the current article. An explosive atmosphere can be created by the powder form of these polymer materials, and introduction of preventive safeguards to ensure safety is required for their use. Although the fire parameters of these basic types of polymers are available in databases (e.g., GESTIS-DustEx), our results showed that one of the samples used (polypropylene) was not flammable and thus is safe for use in terms of explosiveness. Two samples were flammable and explosive. The lower explosive limit was 30 g·m−3 (PA12) and 60 g·m−3 (UHMW polyethylene). The maximum explosion pressure of the samples was 6.47 (UHMW polyethylene) and 6.76 bar (PA12). The explosion constant, Kst, of the samples was 116.6 bar·m·s−1 (PA12) and 97.1 bar·m·s−1 (UHMW polyethylene). Therefore, when using polymers in production technologies, it is necessary to know their fire parameters, and to design effective explosion prevention (e.g., ventilation, explosive-proof material, etc.) measures for flammable and explosive polymers.Ministerstvo školstva, vedy, výskumu a športu Slovenskej republiky, (020STU-4/2021); Agentúra na Podporu Výskumu a Vývoja, APVV, (APVV-21-0187)Cultural and Educational Grant Agency of the Ministry of Education, Science, Research and Sport of the Slovak Republi

Investigation of accidents in the chemical industry

Práce se zabývá aplikací systematických technik vhodných pro vyšetřování havárií v chemickém průmyslu v České republice. V úvodu je uvedena diskuse o vyšetřování nehod ve světě a v České republice. Moderní vyšetřovací metody nehod jsou založené na systematických technikách. Pro práci byla vybraná systematická technika vyšetřování nehod poskytující kořenové příčiny. Samotná práce je zaměřená na metodu Management Oversight and Risk Tree - MORT. V rámci práce byl vytvořen nástroj MORT WorkSheet, který ulehčuje a zjednodušuje praktickou aplikaci metody MORT. Praktická část se zabývá vyšetřováním vybraných nehod pomocí MORT WorkSheet. Výsledky vyšetřování jsou v závěrečné části práce. V závěru jsou diskutované přínosy metody MORT nejen vzhledem k tradičnímu vyšetřování nehod a k ostatním vyšetřovacím technikám, ale též i vyšetřování nehod v chemickém průmyslu.Ústav energetických materiálůDokončená práce s úspěšnou obhajobo

Risk Analysis Possibilities in the Fire Protection

Riziká sa nachádzajú všade okolo nás. Jedným z najčastejších prejavov rizík sú požiare. Ich zvládanie a likvidácia je úlohou požiarnej ochrany a všetkých súvisiacich profesií. Je dôležitejšie požiarom predchádzať ako ich hasiť. Je potom dôležité vedieť, čo je a čo nie je riziko. Túto úlohu môže vyriešiť analýza rizík. Využíva softvérové nástroje alebo sofistikované postupy a metódy. Niektoré informácie o vybraných metódach a nástrojoch sú uvedené v tomto príspevku.Risks are everywhere around us. One of the most often symptoms of risks are fires. Fire management and liquidation is the role of fire protection and all related professions. The important role of fire protection is to avoid risk of fires. Therefore it is important to know, what the risk is in an evaluated system. This task can be resolved by use of risk analysis. Risk analysis uses software or sophisticated procedures and methods. Some information on selected methods and tools of risk analysis are described in this article

Accidents investigation by Fault Tree Analysis methods

Práce prokázala, že metoda Fault Tree Analysis je vhodná a poměrně rychlá technika hodnocení havárií. Výhodou je, že výsledné kritické řezy se dají ohodnotit pravděpodobnostmi, což urychluje nápravu událostí, které by se mohly často vyskytovat.Katedra teorie a technologie výbušninDokončená práce s úspěšnou obhajobo

Toward a Congress Raj: Indian nationalism and the pursuit of a potential nation-state

Near the colonial period in India, the British suspected that the Indian National Congress acted as if it were a parallel government. My research shows that Congress elites constructed the institutions that would enable Indians to govern themselves after India\u27s liberation from British imperialism. Between 1935 and 1939, Congress elites surmised about the potentialities of a post-colonial India. They developed the policies that engaged the Congress with a process of state formation and constructed the ideological and practical foundations of a truly Indian governmentality, a new synthetic ideal of centralized government. With independence defined as national control of functions central government, Congress elites generated the independent instruments of governance analogous to the extant structures of the Raj. The principle of non-cooperation with imperialism remained the foundation of all endeavors for generating a proto-government. Congress elites grappled with creating a national government that was ideologically distinct from Britain\u27s footprint in India but which resembled the colonial restructuring of Indian society and politics. The emerging proto-government was a hybrid between Indian and British institutions, a synthesis which could remain a unique structure and that claimed its distinctiveness from Britain\u27s paternalism. My dissertation next investigates this emerging governmentality. Congress elites\u27 attitudes towards democracy are investigated to determine how applicable democratic practices were to the post-colonial state. Attitudes towards international events are considered to illustrate that India\u27s foreign policy challenged Britain\u27s international attitudes. An independent economic policy was imperative if the Congress\u27s proclaimed desire to ameliorate India\u27s poverty was anything more than oppositional dialogue. Congress elites\u27 attitudes towards a strong centralized government are considered to illustrate the federal structure of independent India. This process of state formation was interrupted by World War II. Congress elites turned away from developing the potential institutions of governance and instead emphasized the creation of a so-called \u27national government.\u27 Congress elites never recovered from this new trajectory and they unequivocally abandoned all attempts to inaugurate a true Congress Raj. After the war, Congress elites discarded their ideal governmentality for the Congress\u27s control of the Centre, a move designed to prevent the disintegration of the fledgling Indian Republic

DETERMINATION OF EXPLOSION CHARACTERISTICS OF SUGAR DUST CLOUDS

A dust explosion occurs when an airborne combustible dust cloud encounters an effective ignition source. The resulting pressure and temperature increase can severely injure people and damage surrounding equipment and buildings, and therefore needs to be prevented or controlled (Taveau, 2016). The article deals with the measurement of maximum explosion pressure and maximum rate of explosion pressure rise of sugar dust cloud. The measurements were carried out according to STN EN 14034-1+A1:2011 Determination of explosion characteristics of dust clouds. Part 1: Determination of the maximum explosion pressure pmax of dust clouds, the maximum rate of explosion pressure rise according to STN EN 14034-2+A1:2012 Determination of explosion characteristics of dust clouds - Part 2: Determination of the maximum rate of explosion pressure rise (dp/dt) max of dust clouds and Determination of explosion characteristics of dust clouds. Part 3:Determination of the lower explosion limit LEL of dust clouds. The sugar dust cloud in the chamber is achieved mechanically. The testing of explosions of sugar dust clouds showed that the maximum value of the pressure was reached at concentrations of 1000 g / m3 and its value is 6,89 bars