The effect of mechanical activation on the carbothermic reduction of nickel oxide was investigated. Mixtures of nickel oxide and activated carbon (99% carbon) were milled for different periods of ...time in a planetary ball mill. The unmilled mixture and milled samples were subjected to thermogravimetric analysis (TGA) under an argon atmosphere and their solid products of the reduction reaction were studied using XRD experiments. TGA showed that the reduction of NiO started at ~800? and ~720? in un-milled and one-hour milled samples respectively whilst after 25h of milling it decreased to about 430?. The kinetics parameters of carbothermic reduction were determined using non-isothermal method (Coats-Redfern Method) for un-milled and milled samples. The activation energy was determined to be about 222 kJ mol-1for un-milled mixture whilst it was decreased to about 148 kJ mol-1 in 25-h milled sample. The decrease in the particle size/crystallite size of the milled samples resulted in a significant drop in the reaction temperature.
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Tekst potvrđuje zagrebačku protokonceptualnu skupinu Gorgona kao antiestetsko i antislikarsko društvo, koje nastoji inicirati reviziju zatečene umjetnosti, desakralizirati umjetničko stvaranje, ...sekularizirati umjetničko djelo i njezinu poruku. Protegnula se Gorgona u prostor mentalne slobode i demistifikacije samog jezika umjetnosti. U gorgonaškim rukopisima stvarnost likovnog djela pregnantno i dojmljivo nastupa kao nešto samostalno i samodostatno, slobodno od tradicionalnih, kanoniziranih, propisanih i akademiziranih navada predstavljačkog slikarstva. Kritičko preispitivanje funkcije umjetnosti i umjetničkog jezika otkrilo je gorgonašima konvenciju slike kao neprimjerenu etici umjetnosti. Slikanje – sada doživljeno kao zastarjeli i potrošeni instrument umjetničke ekspresije – nastoji se svesti na minimum, a zapravo ga – konceptualno – nastoje izbaciti iz konteksta umjetničkog, premda si članovi grupe – izvan gorgonaških aktivnosti – dopuštaju i slikanje. Gorgonaši afirmiraju bihevioralnu i verbalnu poziciju umjetnika, pa se o mediju „čistog” slikarstva može govoriti tek u kontekstu njegove negacije. Rad posebice predstavlja antislikarske radove Josipa Vanište kojima nadilazi i nadvladava pojam slike, pretvarajući je u tekst.
In the present study, feasibility of aluminothermic reduction of molybdenum oxide by microwave oven was studied. Furthermore, the effect of compaction pressure and the amount of used Al and CaO as ...flux on aluminothermic reduction of molybdenum oxide were investigated. Thermodynamic analysis of the corresponding reaction indicated that, aluminothermic reduction of MoO3 was possible at all temperatures. XRD patterns and thermodynamic investigation of reaction products indicated that aluminothermic reduction of molybdenum oxide progressed through the formation of intermediate phases such as Al2 (MoO4)3 and MoO2, where the final products were elemental Mo and Al2O3. Results revealed that by increasing the compaction pressure of the pellet, undesired phases of molybdenum dioxide (MoO2) and aluminum molybdate Al2(MoO4)3 can be detected among the final products. By increasing the amount of Al more than stoichiometric ratio, the intermediate phases, such as MoO2, were produced. The results indicated that by adding CaO to the MoO3-Al system, the unwanted molybdenum dioxide (MoO2) and aluminum molybdate (Al2 (MoO4)3) compounds were successfully reduced to Mo.. In the present work, metallic molybdenum could easily and successfully be separated from Al2O3 slag, as the side product of the reaction, in molten phase, based on the difference in their densities.
Mikotoksini su sekundarni metaboliti plijesni koji predstavljaju značajan problem u području sigurnosti hrane te predstavljaju rizik za zdravlje te dobrobit ljudi i životinja. Učinkovitost metoda ...uklanjanja mikotoksina iz hrane i hrane za životinje, primarno žitarica kao najviše
kontaminirane grupe hrane, ovisi o brojnim parametrima, od kojih su vrlo značajni svojstva onečišćenog materijala, odnosno njegov sastav, primarno sadržaj vode, te razina onečišćenja. Ovaj rad daje pregled fizikalnih i kemijskih metoda koje se manje ili više učinkovito mogu koristiti u tretmanu različitih vrsta hrane i hrane za životinje u cilju
redukcije odnosno uklanjanja mikotoksina. Uklanjanje mikotoksina fizikalnim metodama uključuje njihovu ekstrakciju pomoću otapala, adsorpciju te toplinsku inaktivaciju ili inaktivaciju ozračivanjem. Najznačajnije metode su sortiranje po boji i gustoći, ljuštenje i mljevenje, flotacija, blanširanje, prženje, a u posljednje vrijeme vrlo značajna je primjena gama zračenja te hladne plazme. Uporabom kemijskih metoda koje podrazumijevaju primjenu kemikalija dolazi do konverzije mikotoksina u druge manje toksične spojeve, npr. kiseline, lužine, oksidanse, bisulfite i plinove, no moguća je konverzija i u toksičnije spojeve, što je još uvijek predmet brojnih istraživanja. Za razliku od fizikalnih metoda, kemijske metode uklanjanja mikotoksina u načelu se smatraju nepraktičnim i nepoželjnim, zbog uvjeta provedbe, stvaranja toksičnih ostataka te negativnog utjecaja na nutritivna, senzorska i funkcionalna svojstva proizvoda.
In order to choose the optimal parameters for easier diagnosis of systemic autoimmune diseases, the authors focused on data dimensionality reduction, using both feature selection and feature ...extraction. The Multiple Correspondence Analysis was used as a feature extraction method, with the aim of exploring the underlying data structure and detecting the crucial latent variables. The obtained latent variables were used as an input for the Discriminant Analysis which correctly classified 86.5% of all analyzed cases. The high rate of correctly classified objects indicates that it would be possible to automate diagnostic processes, which would lead towards the development of decision support systems in this area of medicine. In addition to their knowledge and experience, clinical experts would have further help in decision support systems. That can allow easier learning, faster checking of diagnostic steps, lower rates of misdiagnosed cases and easier communication with experts from other medical centers. / В данной работе представлена так называемая редукция размерности данных, проведенная методом селекции и экстракции характерных атрибутов, с целью выбора оптимальных параметров для диагностики заболеваний иммунной системы. Анализ множественной корреспонденции проведен не только при экстракции, но и при исследовании самой структуры данных, а также при диагностике латентных переменных. Благодаря проведенному анализу множественной корреспонденции на материале экстрагированных латентных переменных с максимальной точностью было классифицировано 86,5% наблюдаемых случаев. Высокий уровень точно классифицированных заболеваний свидетельствует о реальных возможностях автоматизации диагностических процессов, которая поможет в усовершенствовании системы поддержки диагностики системных заболеваний соединительной ткани. Данные системы отличаются надежностью и скоростью диагностики, они легко осваиваются и облегчают коммуникацию специалистов из различных медицинских учреждений. / Radi izbora optimalnih parametara u dijagnostici sistemskih autoimunih bolesti, autori su se u ovom radu fokusirali na tzv. reduckiju dimenzionalnosti podataka upotrebom metoda selekcije i ekstrakcije karakterističnih atributa. Višestruka analiza korespondencije korišćena je ne samo za ekstrakciju, već i za ispitivanje same strukture podataka, kao i za detekciju ključnih latentnih promenljivih. Na ekstrahovane latentne promenljive je, primenom diskriminantne analize, korektno klasifikovano 86,5% posmatranih slučajeva. Visoka uspešnost klasifikacije upućuje na realne mogućnosti automatizacije dijagnostičkog procesa, što bi rezultiralo razvojem sistema za podršku u dijagnostici sistemskih bolesti vezivnog tkiva. Ovakvi sistemi omogućuju lakše učenje, bržu i pouzdaniju dijagnostiku i lakšu komunikaciju sa ekspertima iz drugih medicinskih centara.
Fuel consumption in blast furnaces depends on many factors that are mainly conditioned by the technological level of a given blast furnace, the steel mill in which it operates, and the type and ...quality of ferrous feed, coke, and additional reducing agents. These are global factors which a furnace crew cannot control during operation. On the other hand, using their own experience and decision-making software, a crew can run a blast furnace with minimal fuel consumption under current batch and process conditions. The paper presents a model-based algorithm for optimizing the operation of blast furnaces to achieve the lowest fuel consumption. The algorithm allows the heat demands to be continuously calculated and highlights any wastage that could be reduced without affecting the stable operation of the blast furnace.
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The effect of coal ratio on the high-lead slag reduction was reported in this article. First, the phase diagrams of the PbOFeO- SiO2-2%CaO-10%ZnO slag system at various temperatures and coal ratios ...were thermodynamically constructed. Next, the density, the melting temperature, the viscosity, the chemical composition and the phase transformation of the reduced slag were investigated. The thermodynamic results indicated that the variation of coal ratio could affect the chemical composition of the reduced slag, which led the physical properties of the reduced slag to change further. The experimental results illustrated that the content of lead and copper in the reduced slag decreased, while the contents of iron, silicon, calcium and zinc in the reduced slag increased as the coal ratio increased, which led the density and viscosity of the reduced slag to decrease further. The melting temperature of the reduced slag increased sharply when the coal ratio varied in the range of 1.5% to 3%. The mineralogy of the reduced slag indicated that lead mainly existed in the reduced slag in the form of metallic lead, while the iron and zinc were mainly enriched in the reduced slag in the form of a silicate phase. The industrial verification test results demonstrated that the average recovery rate of the lead exceeded 96.0%, the average lead content in the reduced slag was below 2.0% and the average fume rate was approximately 12.0%.
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The reaction mechanism of MoS2-Fe2O3 aluminothermic reduction in the presence of lime using microwave-assisted combustion synthesis method was surveyed. Achieving technical feasibility in one-step ...production of ferromolybdenum along with sulfur removing in solid form are the main features of this novel process. Simultaneous Preliminary thermoanalytical investigations DSC/TGA and X-ray diffraction experiments during the heating process of 0.42MoS2 +1.14Al + 0.29Fe2O3 +0.84CaO demonstrated four key sequential endothermic and exothermic reactions at 420, 540, 660, and 810?C. The most noteworthy reactions involve evaporation of moisture and volatile matter, molybdenite roasting, simultaneous production of lateral compounds such as CaMoO4 and CaSO4, aluminum melting transition, and final termite reaction. Kinetics procedure of the system was conducted using a classical model-free approach by Kissinger?Akahira?Sunose (KAS) method. In this study, the activation energy was determined about 106.4 (kJ.mol-1) for thermite reaction in the temperature range of 810 to 918?C.
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Citrinin u hrani i hrani za zivotinje Pleadin, Jelka; Kudumija, Nina; Frece, Jadranka ...
Hrvatski časopis za prehrambenu tehnologiju, biotehnologiju i nutricionizam,
12/2015, Letnik:
10, Številka:
3/4
Journal Article
Odprti dostop
Mikotoksini su česti onečišćivači hrane i hrane za životinje, primarno žitarica i proizvoda na bazi žitarica. Među njima citrinin predstavlja mikotoksin iz skupine poliketida kojeg sintetiziraju ...plijesni iz roda Penicillium (P. citrinum, P. viridicatum, P. expansum, P. notatum), Aspergillus i Monascus. P. citrinum kao najznačajniji producent citrinina je vrlo raširena i može se izolirati iz velikog broja namirnica i stočne hrane. Toksičnost citrinina nije detaljno proučena te nema dovoljno podataka koji ukazuju na toksične učinke u ljudi. Međutim, u pojedinih životinjskih vrsta dokazana je njegova nefrotoksičnost, embriotoksičnost, teratogenost i genotoksičnost. Zbog nedovoljnog broja dokaza Međunarodna agencija za istraživanje raka (IARC) uvrstila je citrinin u skupinu 3 kao spoj koji se ne može klasificirati kao ljudski karcinogen. S obzirom na nedostatnost podataka, nužna su daljnja istraživanja njegove toksičnosti, prisutnosti u hrani i hrani za životinje te perzistentnosti u tkivima ljudi i životinja kao posljedice izloženosti onečišćenoj hrani ili hrani za životinje. Budući je onečišćenje i ovim mikotoksinom neizbježno, potreban je sustavan nadzor sirovina i finalnih proizvoda namijenjenih ishrani ljudi odnosno hranidbi životinja, kao i definiranje najvećih dopuštenih količina za različite vrste proizvoda putem zakonodavstva.