Processes at the inetrface molten metal-sand mold

The processes that take place at the liquid metal-sand mold interface during the casting and crystallization of metal were studied in this paper. The mold was made using the CO2 – method, with the addition of active components, such as: MgO, TiO2, AlK(SO4)2 and Na2SO4. At the liquid steel pouring temperature, these active components undergo decomposition in the mold, caused by heat release during pouring, crystallization and cooling of castings. Silicates, which have an important influence on casting surface quality, are formed as a result of the interaction between the mould material and liquid steel

Promene EKG tokom hiperinfuzione terapije konja sa hroničnim opstruktivnim oboljenjima

This study describes investigations into the electrocardiogram changes in 27 horses with chronic obstructive pulmonary disease (COPD), during hyperinfusion therapy with isotonic saline solution. Immediately after hyperinfusion therapy the equine ECG showed a temporary sinus tachycardia without atrial and ventricular rhythm disturbances. After infusion a highly significant shortening of the PQ-, QT and TP-intervals was observed. There was a positive correlation between the RR-interval and the duration of the PQ- and QT-intervals, but not with the duration of the P-, QRS- and T-waves.Ova studija opisuje ispitivanja promena u elektrokardiogramu 27 konja sa hroničnim plućnim oboljenjima (COPD) utoku hiperinfuzione terapije izotoničnim rastvorom soli. Neposredno posle hiperinfuzione terapije, EKG konja je pokazivao postojanje povremene sinusne tahikardije bez poremećaja ritma rada pretkomora i komora. Posle infuzije zapaženo je veoma izraženo skraćenje PQ, QT, TP intervala. Izražena je povezanost između RR intervala i trajanja PQ i QT intervala, ali ne i sa pojavom P, QRS i T talasa

Diffusion weighted imaging and magnetic resonance-spectroscopy in differentation of brain tumors

Тумори који захватају централи нервни систем, првенствено ендокранијум, представљају посебан изазов у дијагностици магнетном резонанцијом. Класични преглед овом техником често не даје довољно информација неопходних, како за њихово међусобно разликовање, тако и за разликовање од других не-туморских патологија...Central nervous system tumours, especially brain, make their diagnostics and differentiation by use of magnetic resonance imaging difficult. Usualyy it doesn’t give enough information for their differentiation..

Dijagnoza, anestezija i operativni zahvat kod rupture mokraćne bešike novorođene ždrebadi

This study describes methods for the diagnosis, anesthesia and operative repair in 4 neonatal foals with urinary bladder rupture. Diagnosis was based on case history, clinical signs, changes in serum chemistry analyzes (hyponatremia, hyperkalemia, hypochloremia, metabolic acidosis and increased serum creatinine and urea nitrogen levels), abdominocentesis, ultrasound and electrocardiographs. As electrolyte abnormalities and acid-base derangement can lead to the development of cardiac arrhythmia during general anesthesia, surgical treatment of urinary bladder rupture in neonatal foals should be performed when the animal's condition has been stabilized. This includes infusion of physiological saline solution, 5 % glucose infusion with insulin (0.1U/kg) and 1.4% sodiumdrogencarbonate.Ova studija opsuje dijagnostikovanje, anesteziju i operativni tretman pri rupturi mokraćne bešike novorođene ždrebadi. Dijagnoza je zasnovana na istoriji bolesti, kliničkim simptomima, promenama u serumu ustanovljenim biohemijskim analizama (hiponatrijemija, hipokalijemija, hipohloremija, metabolička acidoza sa porastom nivoa serumskog kreatinina i ureje), abdominocintezi, ultrazvuku i elektrokardiografiji. Kao što poremećaji elektrolita i acido-bazne ravnoteže mogu dovesti do pojave srčane aritmije u toku opšte anestezije, hirurški tretman rupture bešike kod novorođene ždrebadi može biti primenjen kada je stabilizovano zdravstveno stanje životinje. Ovo uključuje infuziju fiziološkog rastvora, 5% glukoze sa insulinom (0,1 U/kg) i 1,4% Na-bikarbonat

EXTREME PRECIPITATION INDICES IN VOJVODINA REGION (SERBIA)

The evolution of daily extreme precipitation from 1966 to 2013 in Vojvodina Region (Serbia) was investigated. We calculated trends of ten precipitation indices and tested their corresponding significances using the Student’s t-test for seven locations. The obtained results suggest that the climate of the northern and central parts of Vojvodina region becomes wetter in terms of precipitation magnitude and frequency, reflecting the characteristic of the central European regime, while the southernmost part of the region is drier, reflecting the characteristic of the Mediterranean regime. In addition, the results indicate an increase in the amount of precipitation in short time intervals. Positive annual trends are strongly influenced by the significant increase of autumn frequency and intensity of extreme precipitation. According to the correlation between extreme precipitation indices and atmospheric teleconnection patterns, it was found that the NAO has the strongest influence on precipitation intensity indices in spring and winter, while during winter it also affects the frequency of dry conditions. The EAWR pattern has a strong influence on the statistically significant positive autumn trends

Translokacija i retranslokacija kadmijuma u grašku (Pisum sativum L.)

Under semi-controlled conditions, we studied cadmium (Cd) translocation and retranslocation in the aphylla pea cultivar Jezero at two stages of growth and development. The applied Cd concentrations were 0 (control), 10-7 and 10-5 M Cd and the age of plants at the time of treatment was 26 and 63 days. The application of Cd via the root lasted for 48 h. The plants were analyzed immediately after the treatment, 38 days later and at maturity. Dry matter mass and Cd contents were determined in individual plant organs. The results showed that dry mass had decreased noticeably depending on the Cd concentration used and plant age. The decrease of dry matter mass in both vegetative and generative plant organs was more significant when Cd was applied at flowering (63 day-old plants) than when the plants were younger (25 day-old). In all the treatments, the highest Cd content was found in the root. The translocation of Cd from the root to the aboveground vegetative and generative plant parts took place and it was relatively more intensive at the lower Cd concentration than at the higher one. The possibility that a minor amount of Cd was retranslocated from the leaves to the seeds and pods could not be ruled out either.Proučavana je translokacija i retranslokaiija kadmijuma (Cd) u afila tipu graška sorte Jezero, u dva stadijuma rasta i razvića, u polukontrolisanim uslovima. Primenjene koncentracije Cd bile su 0 (kontrola), 10-7 i 10-5 M Cd, a starost biljaka u vreme tretmana bila je 26 i 63 dana. Tretmani Cd preko ko-rena trajali su po 48 h. Biljke su analizirane neposredno nakon tretmana, 38 dana kasnije i u fazi zrelosti. Suva masa biljaka i sadržaj Cd određeni su u pojedinačnim biljnim organima. Rezultati su pokazali da se masa suve materije značajno smanjila u zavisnosti od primenjene koncentracije Cd i starosti biljaka. Smanjenje mase suve materije i vegetativnih i generativnih organa bilo je značajnije kada je Cd primenjivan u fazi cvetanja (63 dana stare biljke) nego kada su biljke bile mlađe (25 dana stare). Kod svih tretmana, najviši sadržaj Cd utvrđen je u korenu. Takođe, došlo je do translokacije Cd iz korena u nadzemne vegetativne i generativne biljne organe i ovaj proces je bio relativno intenzivniji kada je primenjena koncentracija Cd bila niža. Mogućnost da je došlo do retranslokacije minimalnih količina Cd iz listova u mahune takođe ne može biti isključena

Uticaj endotelina i L-NAME na koncentraciju mokraćne kiseline i uree u plazmi kod Wistar pacova

Effects of endothelins, which include vasoconstriction and vasodilatation are possible by different molecular mechanisms. Endothelins induce increased synthesis of nitric oxide which in turn inhibits the synthesis of endothelin. Changes in biochemical parameters connected with the increased and decreased synthesis of nitric oxide are not thoroughly examined yet. In a series of experiments we compared the effects of endothelin (ET-1) on the inhibition of nitric oxide synthase (NOS), as well as the effects of L-nitro arginin metal estar (L-NAME) on plasma urea and uric acid concentration. Experiments were performed on anesthetized female adult Wistar rats. The experimental groups received an i. v. bolus of ET-1, L-NAME or saline. All parameters, heamodynamic and biochemical, were measured before the animals were sacrificed. L-NAME increased the mean arterial pressure, decreased renal blood flow and increased vascular resistance in carotid and renal arteries and increased in plasma uric acid and urea concentrations. ET- 1 significantly decreased uric acid concentration in the plasma but did not effect plasma urea concentration compared to the control group. These differences show complex relations of nitric oxide with cellular signalization compared to the basic NO-cGMP pathway.Efekti endotelina koji uključuju vazokonstrikciju I vazodilataciju ostvaruju se različitim molekularnim mehanizmima. Endotelin indukuje povećanu sintezu azotnog oksida za koji se smatra da povratno inhibira sintezu endotelina. Promene biohemijskih parametara vezanih za povećanu i smanjenu sintezu NO nisu dovoljno proučene. U ovom radu su upoređeni efekti endotelina (ET-1) i inhibitora NOS-a, L-NAME na koncentraciju mokraćne kiseline i uree u plazmi. Eksperimenti su izvedeni na anesteziranim odraslim NW pacovima, ženskog pola. Eksperimentalne životinje su u i.v. bolusu primale ET-1, L-NAME ili fiziološki rastvor. Svi hemodinamski i biohemijski parametri su mereni pre žrtvovanja. L-NAME dovodi do povećanja srednjeg arterijskog pritiska smanjenja renalnog protoka i povećanja vaskularnog otpora u karotidnoj i renalnoj arteriji i povećanja koncentracije mokraćne kiseline i uree u plazmi. ET-1 značajno smanjuje koncentraciju mokraćne kiseline u plazmi ali ne utiče na koncentraciju uree u odnosu na kontrolu. Ove razlike pokazuju kompleksnije relacije NO-a sa ćelijskom signalizacijom u odnosu na osnovni NO-cGMP put

Mogućnost povećanja efikasnosti proizvodnje Al legura primjenom elektromagnetnog polja

The relationships between electromagnetic frequency, microstructure and mechanical properties of continuous casting aluminum alloys were studied in this paper. EN AW 2024 and EN AW 2007 aluminum alloys ingots were produced by electromagnetic continuous casting process. The microstructure and mechanical properties of as cast ingots were examined. The results showed that electromagnetic field, especially low frequency electromagnetic field, greatly influenced the microstructure and mechanical properties of as cast ingots. The significant energy savings and product quality can be achieved by the application of a proper frequency.U radu je prikazan utjecaj frekvencije na mikrostrukturu i mehanička svojstva Al legura dobijenih kontinuiranim elektromagnetnim postupkom ljevanja. Ispitivanja su obavljena sa dvije legure EN AW 2024 i EN AW 2007. Mikrostrukturna i mehanička karakterizacija urađena je na uzorcima u ljevanom stanju. Rezultati istraživanja pokazuju da elektromagnetno polje, posebno polje niže frekvencije, utječe na mikrostrukturu i mehanička svojstva ljevanih ingota. Na osnovu dobijenih rezultata može se zaključiti da se primjenom elektromagnetnog polja odgovarajuće frekvencije može postići značajna ušteda energije kao i poboljšanje kvaliteta dobijenih ingota