Organizing transportation on a double-track line under conditions of major overhaul on one track

The problem of traffic organization on a railway line during the execution of civil works on super and sub-structures maintenance under the present conditions is becoming more and more difficult to solve, above all, due to the increased traffic intensity. In order to make decisions on indispensable measures to be taken under such circumstances, one needs information on train compositions and their delays, line capacity, facilities, etc. In order to obtain such information, it is necessary to use a computer simulation which significantly enhances the range of the problem to be solved and offers answers to the questions that cannot be solved by analytical models alone. The paper presents a simulation model of the trains’ movement on a double-track line when one track is closed to traffic due to the work executions. Such model will provide a better quality of decision-making in the process of traffic organization under given circumstances

Bond strength of orthodontic adhesives

The objective of this study was to evaluate and compare bond strength of four adhesives used in orthodontics for bonding brackets to tooth enamel. The adhesives used in this investigation were resin-reinforced glass-ionomer cement (Fuji Ortho LC-GC Corporation, Japan), light cured composite resin adhesives (ConTec LC-Dentaurum, Germany and Enlight Bonding system-Ormco, USA) and dual cured composite resin adhesive (ConTec Duo-Dent aurum, Germany). A sample of 80 extracted human premolars was divided into four groups of 20 teeth which were etched with 37% phosphoric acid and bonded in dry field to enamel of buccal and lingual surfaces of the teeth with the same adhesive in one group. The debonding force was produced using universal Instron testing machine with cross head speed of 1mm/min and shear bond strength was measured. Statistical analysis used in this study included: Kolmogorov-Smirnov test i Shapiro-Wilk test, Mann Whitney test, Kruskal Wallis chi-squared test. Even though, all four adhesives showed sufficient bond strength for orthodontic bonding, ConTec LC and ConTec Duo displayed the superior bonding properties comparing to Enlight and Fuji Ortho LC.

Investigation of phase equilibria and characterization of alloys in the Bi-Cu-Ni system

Fazne ravnoteže u Bi-Cu-Ni ternarnom sistemu proucavane su eksperimentalnim metodama (SEM-EDS, DTA i DSC), kao i analiticki primenom CALPHAD metode. Proracun ravnotežnih faznih dijagrama u Bi-Cu-Ni sistemu izveden je na osnovu optimiziranih termodinamickih parametara za sastavne binarne sisteme i dodatnih termodinamickih parametara, odredenih u ovom radu. Proracunati fazni dijagrami izotermalnih preseka na 300oC, 400oC i 500oC uporedeni su sa eksperimentalnim rezultatima iz literature i ustanovljeno je dobro medusobno slaganje. Definisani su ternarni termodinamicki parametri za tecnu fazu, i BiNi fazu u kojima je uzeta u obzir eksperimentalno potvrdena rastvorljivost bakra u BiNi fazi. Proracunati fazni dijagrami tri vertikalna preseka uporedeni su sa DTA/DSC rezultatima iz ovog rada. Odredene su tvrdoca i elektricna provodljivost kao dopunska karakterizacija legura ispitivanog Bi-Cu-Ni ternarnog sistema.Phase equilibria in the Bi-Cu-Ni ternary system have been studied experimentally using SEM-EDS, DTA and DSC methods, and analytically using CALPHAD method. Calculation of equilibrium phase diagrams of Bi-Cu-Ni system was performed using optimized thermodynamic parameters of the constituent binary systems and additional thermodynamic parameters determined in this study. Calculated isothermal sections at 300oC, 400oC and 500oC were compared with experimental results from the literature and good agreement is found. Ternary thermodynamic parameters for the liquid phase were determined, as well as for the BiNi phase, in which the experimental confirmation of copper solubility in BiNi phase was taken into account. Three calculated vertical sections were compared with the DTA/DSC results from this work. Hardness and electrical conductivity as an additional characterization of the investigated alloys of Bi-Cu-Ni ternary system were determined

Orthodontic treatment of nongrowing patient with class II division 2 malocclusion by Herbst appliance

Background. Inheritance is most casual etiological factor of Class II division 2 malocclusion. This kind of malocclusion is very difficult for treatment specially in older patients. Case report. In the female patient, 20 years old, at the beginning of the treatment at the School of Dentistry in Belgrade, lateral cephalogram showed skeletal and dentoalveolar Class II division 2 malocclusion. She was in the Herbst treatment for 8 months and 12 months more with a fixed multibracket appliance. The measurements were performed on lateral cephalograms before and after the treatment: ii, is, mi, ms, Pg and ss. The distance from these points to occlusal perpendicular line (Olp) were measured and compared from cephalogram before to cephalogram after the treatment. Temporomandibular joint (TMJ) tomograms were compared from before and after the treatment by superimposition. Correction was found in molar and incisor relation, overjet and overbite. There were found sagital skeletal changes and soft tissue profile improvement. Conclusion. Herbst appliance is effective in the treatment of Class II malocclusions, even in adult patients. Dental and skeletal changes as a result of Herbst treatment could be good choice instead of camouflage orthodontics or surgical decision

Importance of medium chain fatty acids in animal nutrition

Fats in animal and human nutrition are a common subject of research. These studies most often pay attention to particular fat groups (saturated, unsaturated, polyunsaturated fats or fats grouped by the length of their fatty acid chains into short, medium or long chain fatty acids). Medium chain fatty acids (MCFAs) have two main sources: milk and coconut oil. To date, research has shown these acids have positive effects on health, production, feed digestibility and lower body and muscle fats in broilers and swine. MCFAs possess antibacterial, anticoccidial and antiviral effects. Also, it has been proven that these acids act synergistically if they are used together with organic acids, essential oils, or probiotics. Nowadays, commercial MCFA products are available for use in animal nutrition as feed additives

Review of the past, present, and future of the hydrometallurgical production of nickel and cobalt from lateritic ores

Laterite ores are becoming the most important global source of nickel and cobalt. Pyrometallurgical processing of the laterites is still a dominant technology, but the share of nickel and cobalt produced by the application of various hydrometallurgical technologies is increasing. Hydrometallurgy is a less energy-demanding process, resulting in lower operational costs and environmental impacts. This review covers past technologies for hydrometallurgical processing of nickel and cobalt (Caron), current technologies (high-pressure acid leaching, atmospheric leaching, heap leaching), developing technologies (Direct nickel, Neomet) as well as prospective biotechnologies (Ferredox process)

Kinetics of barite reduction from refractory barite-sulphide ore

Refractory sulphide-barite ore was reduced with carbon in order to release lead, zinc, and copper sulphide from barite-pyrite base. Mineralogical investigations showed that due to the complex structural-textural relationships of lead, copper and zinc minerals with gangue minerals, it is not possible to enrich the ore using the conventional methods of mineral processing. The influence of temperature and time was studied to optimize the conditions, and to determine the kinetics of the barite reduction. The maximum removal of barite from ore was 96.7% at 900oC after 180 min. Chemically controlled kinetic model showed the best compliance with the experimental data. An activation energy of 142 kJ/mol was found

CO2 EMISSION REDUCTION BY USING CORN AS A RAW MATERIAL IN REFINED ALCOHOL PRODUCTION

In the paper, we analyze the operation of a plant producing refined alcohol with a capacity of 25,000 kg/day, which uses corn as the primary raw material. On the site location, there are a cow farm, a plant for the combined production of heat and electricity using biogas, and a distillery production plant. The raw material for biogas is manure from a cow farm. The energy required for the production process and the operation of the supporting systems (space heating, own consumption of the CHP plant, etc.) is obtained by burning biogas and ethanol so that fossil fuels are used only in cases of plant start-up or incident situations of production process failure. The analysis presented in this paper aims to set up a carbon dioxide balance for a production plant with accompanying systems and its comparison to the carbon dioxide consumption necessary for corn's growth.IEEP-Industrijska energetika i zaštita životne sredine u zemljama jugoistočne Evrop

Investigation of the optimal technology for copper leaching from old flotation tailings of the copper mine bor (Serbia)

This work aimed to investigate optimal leaching technology for copper extraction from old flotation tailings of the Copper Mine Bor. The leaching degree of copper after leaching with sulphuric acid at 80 °C was 50%, the maximal leaching degree was achieved after 30 minutes. Then, old flotation tailings were leached with adapted moderately thermophilic acidophilic bacteria in a bioreactor at 40 °C. Maximal leaching degree of 84% was achieved after nine days of the experiment. The third leaching experiment was conducted with biogenic lixiviant obtained by bacterial oxidation of the ferrous iron (concentration of Fe3+ 1300 mgL-1, pH 2.14). Biogenic lixiviant with ferric sulphate was then used in the leaching experiment at 80 °C. Maximal leaching degree was 78%, and it was achieved after five minutes. Results of the leaching experiments show that the most efficient technology for copper recovery from the old flotation tailings of the Copper Mine Bor was leaching with biogenic lixiviant