Self-compacting mortars are achieving a great deal in the construction industry due to their remarkable characteristics and due to their advantages over conventional concrete. The main drawback ...associated with self-compacting mortars is the high cost associated with the ingredients used in the production of self-compacting mortars. This research aims to overcome this by combining the effects of nano-silica and glass powder on the properties of self-compacting mortar at normal and higher temperatures. The experiments were conducted to determine the split tensile strength over a range of curing periods and after being subjected to various temperatures. Durability properties of the self-compacting glass mortar, such as sorptivity, were also studied and compared with the properties of the control mortar. In addition, the chloride penetration resistance of the self-compacting mortars were also studied. The microstructure properties, such as X-ray diffraction and FTIR studies, were also performed to analyze the characteristics of self-compacting glass mortars at the micro level. The proposed mortar design can solve the problem of the disposal of waste glass, prevent the the depletion of natural river aggregates and also prove to be cost effective for massive construction purposes.
Introduction/purpose: Cobalt is a strategic metal for industrial application. Cobalt recovery from oxidic ores such as laterite and sulphidic ores, and from secondary materials during acidic ...treatment and precipitation is a highly used strategy ensuring different products such as cobalt hydroxide, cobalt oxide, and finally metallic cobalt. Methods: Familiarity with cobalt behavior in hydrometallurgical processes such as dissolution at atmospheric and high pressure, precipitation, neutralization, filtration and hydrogen reduction is most important for cobalt recovery from ores and secondary materials. Pyrometallurgical methods such as roasting and flash smelting are applied for the treatment of sulphidic ores combined with solvent extraction and electrolysis in order to obtain cathodic cobalt. Results: Powders of nickel-cobalt hydroxide were obtained from ores using sulphuric acid under high pressure in an autoclave and after precipitation with MgO. Solvent extraction was used to separate cobalt from nickel. The final step of cobalt recovery from a solution is using electrolysis. Cobalt and cobalt compounds such as cobalt carbonate and cobalt hydroxide can be obtained from secondary materials in hydrometallurgical operations. Conclusion: Hydrometallurgical and pyrometallurgical processes are mostly applied for cobalt recovery from primary ores (oxidic and sulphidic compounds) and from secondary materials (cemented tungsten carbide, polycrystalline diamond blanks, and waste cathodic materials from lithiumion batteries). / Введение/цель: Кобальт является стратегическим металлом в промышленном применении. Извлечение кобальта из оксидных руд, таких как латеритные и сульфидные руды, а также из вторичных материалов во время кислотной обработки и осаждения является широко используемым методом, обеспечивающим получение различных соединений, таких как гидроксид кобальта, оксид кобальта и металлический кобальт. Методы: Гидрометаллургические процессы, такие как растворение при атмосферном и высоком давлении, нейтрализация, осаждение и извлечение водородом, использовались для выщелачивания кобальта из руд и вторичных материалов. Пирометаллургические процессы, такие как обжиг и автогенная плавка сульфидных руд, сочетались с экстракцией растворителем и электролизом при получении катодного кобальта. Результаты: Порошки гидроксида никеля и кобальта получены из руды с использованием серной кислоты при высоком давлении в автоклаве и осаждением оксидом магния. Никель и кобальт разделяли с помощью экстракции растворителем. Конечный раствор с кобальтом использовали в процессе электролиза для получения кобальта. Кобальт и его соединения, такие как карбонат кобальта и гидроксид кобальта, получены из вторичного сырья с помощью гидрометаллургических операций. Выводы: Гидрометаллургические и пирометаллургические процессы в основном используются для выделения кобальта из первичных руд (оксидных и сульфидных соединений) и вторичных материалов (цементированные карбиды вольфрама, поликристаллические алмазные пластины и отходы катодных материалов литий-ионных аккумуляторов). / Uvod/cilj: Kobalt je strategijski metal u industrijskoj primeni. Njegovo izdvajanje iz oksidnih ruda, zvanih lateriti, i sulfidnih ruda, kao i sekundarnih materijala tretiranjem kiselinom i precipitacijom najčešće je korišćen metod koji obezbeđuje različite produkte kao što su kobalt hidroksid, kobalt oksid imetalni kobalt. Metode: Hidrometalurški procesi, kao što su rastvaranje pri atmosferskom i visokom pritisku, neutralizacija, precipitacija i redukcija vodonikom korišćeni su za izdvajanje kobalta iz ruda i sekundarnih materijala. Pirometalurški procesi, kao što su prženje i autogeno topljenje sulfidnih ruda, kombinovani su sa solvent ekstrakcijom i elektrolizom za dobijanje katodnog kobalta. Rezultati: Prahovi nikal-kobalt hidroksida dobijeni su iz ruda korišćenjem sumporne kiseline pri visokom pritisku u autoklavu i precipitacijom sa magnezijum oksidom. Nikal i kobalt razdvajani su korišćenjem solvent ekstrakcije. Finalni rastvor sa kobaltom korišćen je u procesu elektrolize za dobijanje kobalta. Kobalt i njegova jedinjenja kao što su kobalt karbonat i kobalt hidroksid dobijaju se iz sekundarnih sirovina pomoću hidrometalurških operacija. Zaključak: Hidrometalurški i pirometalurški procesi većinom su primenjeni za izdvajanje kobalta iz primarnih ruda (oksidna i sulfidna jedinjenja) i sekundarnih materijala (cementirani karbidi volframa, polikristalne dijamantske pločice i otpadni katodni materijali iz litijumjonskih baterija).
As a by-product or material used in various industries crystalline silica contaminates the air many occupational settings. If its fine particles are inhaled, they are deposited in the lungs and may ...cause the development of silicosis, chronic obstructive pulmonary disease, and lung cancer. The goal of this study was to estimate occupational exposure to respirable crystalline silica (RCS) in Slovenia and the associated health risks. To do that, we ran two cross-sectional studies, one to determine the number of workers at risk of occupational exposure to RCS in Slovene industries and the other to determine and classify changes in the lung radiographs of glass factory workers exposed to RCS, as a means to infer health risks for other RCS exposed workers in Slovenia. However, the first study shows that official public data on occupational exposure to silica in Slovenia are unreliable and incomplete and that company representatives strongly underestimate occupational exposure to silica. Measurements of total and silica dust are made by 8.3 % and 1.8 % of companies working with silica, respectively. The second study shows that about a third of the exposed workers had lung changes associated with silicosis. We have failed to achieve the goal of our study, as the obtained data are grossly underestimated and unreliable, but it has opened our eyes as to what needs to be improved. All companies need to systematically be informed about occupational health risks, field inspections need to be consistent, regular, and intensified, and health surveillance of all exposed workers implemented regularly.
In this study, to evaluate the change in the stress and die-wall frictional characteristics during high-velocity compaction (HVC), a metal powder was subjected to HVC with a heavy hammer based on the ...stress-testing technology and Janssen-Walker model. The changes in the green density, stress characteristics and coefficients of friction at different impact heights were investigated. The density of green compacts increased with the increase in the impact height. The stress in the upper and lower punches and the die wall showed repeated loading and unloading. The coefficient of friction of the die wall underwent three stages and was related to powder densification. As the height position along the side wall was increased, the coefficient of friction increased gradually. With an increased impact height, the coefficient of friction increased significantly in the incomplete-molding stage but remained constant in the complete-molding stage. This work expands the theoretical basis of densification processing of a metal powder during HVC.
Studija istražuje konstituciju čovjeka u Post 1–2, proučavajući važnije tekstove o stvaranju čovjeka u Mezopotamiji i biblijske izvještaje u Post 1–2. Pregled tekstova iz Mezopotamije pokazuje da sve ...ondje prisutne tradicije naglašavaju božanske elemente u konstituciji čovjeka, a analiza Post 1–2 otkriva da se oba biblijska izvještaja, i svećenički i jahvistički, takvim idejama protive. Svećenički opis stvaranja čovjeka na sliku Božju (Post 1,26-27) niječe supstancijalnu vezu Boga i čovjeka, koju ističe babilonska tradicija o stvaranju čovjeka od božanskog mesa i krvi, i uvažava samo formalnu vezu, odnosno rašireno uvjerenje o sličnom obliku ljudskog i Božjeg lika. Prema mišljenju svećeničkoga pisca čovjek je sazdan od zemaljske materije, ali oblik ljudskog tijela izvana i iznutra nalikuje Božjem liku i taj božanski oblik omogućuje zemaljskoj materiji bogoliko djelovanje. Jahvistički opis stvaranja čovjeka od praha i daha života (Post 2,7) negira postojanje klice života u zemljanoj konstituciji čovjeka, što naglašava sumerska tradicija o stvaranju čovjeka od božanske zemlje, te pokazuje da je čovjek u svojoj biti smrtno biće. U zaključku studije iznose se najvažniji rezultati te ukazuje na važnost zemaljske antropologije u Post 1–2 za suvremeni teološki diskurs i za kršćansku vjeru.
Silver powders produced by both electrochemical (galvanostatic (DC) and potentiostatic (POT) regimes of electrolysis) and chemical processes were examined by scanning electron microscope, and ...particle size distribution (PSD) of the obtained particles was done. In the DC regime, the current densities of ?14.4 mA cm-2 for the nitrate (NIT; powder denoted with DC(NIT)) and ?13.05 mA cm-2 for the ammonium (AM; DC(AM)) electrolytes were applied. In the POT regime, the used overpotentials were ?90 mV (NIT(90)) and ?150 mV (NIT(150)) for the nitrate, and ?625 mV (AM(625)) and ?925 mV (AM(925)) for the ammonium electrolytes. Reduction with hydrazine was used for chemical synthesis (powder denoted with HYD). On the basis of SEM and PSD analysis, Ag powders were grouped into three groups. In the first group DC(AM), AM(925) and HYD powders with the (8.4?8.9 %) volume ratios were placed. In the second group were AM(625) and DC(NIT) powders with the (6.5?6.6 %) volume ratios. NIT(90) and NIT(150) powders with the volume ratios of (5.2?5.7 %) made the third group. The obtained volume ratios were correlated with the morphology of synthesized particles in order to perceive advantages and lacks of powder production via electrochemical and chemical routes.
nema
V članku so predstavljena izkopavanja kamnitih gomil z žganimi pokopi na območju Vile Prah in s Koroške ceste v Kranju, ki sta jih v letu 1939 opravila R. Ložar in V. Herfort. Na podlagi revizije ...arhivskega gradiva je bilo mogoče deloma rekonstruirati lego posameznih najdb in skupkov najdb, ki pripadajo domnevno več žarnim pokopom znotraj kamnite grobne kamre z območja Vile Prah. Z izkopavanj na Koroški cesti v Kranju so se ohranile grobne celote žarnih grobov. Predstavljene so tudi ostale železnodobne grobne najdbe iz Kranja in Stražišča pri Kranju ter Stanežič pri Ljubljani, ki jih hranijo v Narodnem muzeju Slovenije. Nove ugotovitve ter primerjalna analiza ostalih gorenjskih grobišč kažejo, da se je gomilni pokop na Gorenjskem pojavil že v zgodnji železni dobi, ob tem se je ohranil tudi plan žgani pokop. Večina grobišč, ki so se pojavila v zgodnji železni dobi, so bila konec stopnje Ljubljana IIIa/Podzemelj 2 opuščena. V gradivu s Koroške ceste v Kranju se zrcali vpliv svetolucijske skupine, kar dodatno potrjuje domnevo S. Gabrovca o širjenju interesnega območja svetolucijske skupine na območje Gorenjske.
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