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Boilers are one of the most used units for both heat generation plants and industry systems. Their operation is subjected to different working loads and maintenance requirements. Exploitation experience points out critical boiler zones where failures and break downs typically occur. This paper analyzes critical zones in hot water fire-tube boiler. Experimental procedure was performed on the model of this type of boilers and its critical element. The tube plate of hot water boiler was identified as the most critical one. Experimental analysis and numerical model verification were performed using Aramis system based on 3-D digital image correlation method. Numerical analysis was done in ANSYS software package and verification of results was done based on measurements obtained by strain gauges and local measurements performed by the Aramis system. Stress-strain analysis indicates the critical zones of boiler tube plate. The character of change parameters such as strain and stress occurring in the critical zones can be verified both by experimental and numerical data. The paper presents a novel approach in experimental and numerical analyses that can be conducted in similar units and used for existing unit optimization, as well as for new product testing on different loads and provide opportunity for further development and improvement for practical industrial application.

This work identifies lighting as a non-invasive method for the transformation of a space that simultaneously and unconstructively articulates various activities and does not interfere with the inherited physical framework. Through experimental research and a case study of the "Eastern City Gate of Belgrade" housing settlement in Serbia, which was designed and built in the second half of the 20th century, the activity rhythm of a contemporary user is explored. The research goal was to recognise the decision-making tools for increasing the quality of open public spaces during the night-time mode of use by improving the quality of lighting. The study proposes the new lighting design model that supports night-time leisure activities in mass housing open public spaces in the contemporary urban context.

The aim of the paper is to investigate the transient regime of hot water boiler numerically and experimentally. In the regime of starting up, as the most critical one, measurements were done on the boiler critical element. The operating characteristics as well as safe and reliable operation conditions of hot water boilers are limited by thermal stresses that occur in their structure. The greatest thermal stresses occur in transient operating regimes such as starting-up, changing operation mode or sudden shutdown, resulting in uneven heating or cooling of boiler elements. Large temperature gradients cause high thermal stresses that are especially critical in elements with thick walls. As thermal stresses may limit the heating and cooling rates of temperature changes, boiler structure is exposed to variable temperature and stress field. The largest absolute value of thermal stresses occurs at the inner surface, where direct measurements are not possible to take, since the inner surface is in direct contact with hot water under high pressure. This was the reason to measure the temperature of boiler structure inside the boiler, on tube plate, as one of the critical part of the boiler. In this paper the experimental results of temperature measurement of tube plate were presented, during the regime of starting-up. Numerical model done by FEM was verified by experimental results. The performed analysis showed that the tube plate of the first reversing chamber, the boiler element with the thickest wall, is exposed to the highest thermal stresses. This part of the boiler is exposed to temperatures t>500 ℃ and it is exposed to creep. In conditions of creep, continuous accumulation of plastic deformations occurs at a rate that depends on the level of stress, temperature and material characteristics.

Održivo poslovanje i pozicioniranje kompanija na tržištu zahteva od kompanija da maksimiziraju dodatu vrednost uz minimalno iskorišćenje resursa. Sve veći izazov za kompanije predstavlja racionalna upotreba energije i energetskih izvora, a sve sa ciljem očuvanja životne sredine. Industrijski sistemi, pre svega proizvodni sistemi, predstavljaju najveće potrošače energije. Istraživanje ima za cilj utvrđivanje trenutnog stanja u praktičnoj primeni sistema menadžmenta energijom u proizvodnim i uslužnim sistemima u Srbiji. Motivacija za ovakvu temu je pritisak evropske regulative na primenu mera za uštedu energije, kao i za zaštitu životne sredine. Standardi za sistem menadžmenta energijom, na kojima se ovo istraživanje zasniva, razmatraju energetsku performansu koju postiže organizacija. Jedan od najpoznatijih predstavnika ove vrste standarda je ISO 50001. Istraživanjem su statistički analizirane veze određenih faktora i nivoa primene zahteva za sistem menadžmenta energijom., Sustainable business development and companies market positioning require companies to maximize added value with minimal resource utilization. The rational use of energy and energy sources is also a growing challenge, which aims to preserve the environment. Industrial systems, primarily production systems, are the largest energy consumers. The aim of this research is to determine the current situation regarding the application of energy management practices in production and service systems in Serbia. The motivation for these theme is the pressure of European regulation on the implementation of energy saving measures as well as on the environment. The standard for the energy management system on which this research is based consider the energy performance achieved by the organization. One of the most well-known representatives of this type of standard is ISO 50001. The research has statistically analyzed the relations of certain factors and levels of requirements application for the energy management system

Hot water boilers, especially boilers with fire tube where the combustion takes place, are widely used in process industry. Elements of the boiler are exposed to high pressures and temperatures during boiler operation. Exploitation experience indicates constant and permanent breakdowns occurring as a result of accidental states of individual boiler elements. Studies done before in this field indicate certain critical boiler elements that may have influence on the reliability and safety of the entire unit. In order to avoid this state, certain investigation should be made that would examine the influence of different regimes on the boiler structure. Lack of available data concerning the temperature as well as stress-strain field in boiler elements led us to perform such kind of experiment. This paper presents results of numerical analysis performed on the modelled boiler. Validation of the numerical model was performed based on experimental results obtained using 3D Digital Image Correlation analysis. This paper analyses critical elements of the hot water boiler by experimental data obtained from its model and improved numerical model in order to analyze constrains and loads the model is exposed to and to have fully-covered stress-strain field obtained from experimental data.

In this study, the effect of Cd on the germination, growth of seedlings and composition of plants deriving from contaminated grains, grown in the field, was examined. Wheat grains were soaked in Cd-containing solutions: 0 (control, deionized water), 10-5 , 10-4 , 10-3 , and 10-2 M CdCl 2 during 24h. One portion of grains was used to test germination and seedling growth, while the other was sown in the field. The concentration of Cd in the grains almost linearly increased with the increase in the applied concentrations of Cd, which reduced the germination and energy of germination and increased the proportion of atypical seedlings. Larger concentrations of Cd significantly impaired the growth of seedlings (length of the shoots and roots, dry matter mass). In the grains of the field-grown plants the concentrations of N, P, and K were not affected by Cd, but their concentrations in the straw declined (especially of N). These results suggest that the emergence and development of plants on the soil polluted by Cd are likely to be significantly limited and yield reduced., Kadmijum (Cd) je potencijalni zagađivač sredine živih organizama i pri većim koncentracijama odlikuje se jakim fitotoksičnim dejstvom. U radu je u laboratorijskim uslovima proučeno dejstvo različitih koncentracija kadmijuma na klijanje i rast mladih biljaka pšenice, a u poljskim uslovima njegov uticaj na koncentraciju mineralnih materija u zrnu i slami u fazi pune zrelosti biljaka, koje su potekle od zrna tretiranog kadmijumom. S povećanjem koncentracije kadmijuma u fazi bubrenja semena skoro se linerano povećala njegova koncentracija u semenu. Utvrđeno je da veće koncentracije kadmijuma značajno smanjuje klijanje i energiju klijanja semena, a povećavaju učešće atipičnih klijanaca i neproklijalog semena. Veće koncentracije kadmijuma značajno su smanjile rast mladih biljaka kao i masu njihove suve materije. Rast nadzemnog dela i korena smanjen je u većoj meri od mase suve materije, na osnovu čega se može zaključiti da je kadmijum u većoj meri uticao na faktore rasta nego na stvaranje suve mase. Najveća primenjena koncentracija kadmijuma smanjila je hidratisanost 68 nadzemnog dela mladih biljaka. Bubrenje semena u prisustvu različitih koncentracije kadmijuma nije uticalo na koncentraciju azota, fosfora i kalijuma u zrnu, a smanjilo je njihovo prisustvo u slami, naročito azota na kraju vegetacije. Dobijeni rezultati potvrđuju nalaze ranijih istraživanja kod drugih biljnih vrsta na osnovu kojih su fiziološki i biohemijski procesi klijanja semena značajno inhibirani u prisustvu većih koncentracija kadmijuma. Na osnovu navedenog može se predvideti da će na zemljištu zagađenom kadmijumom nicanje useva i rast mladih biljaka pšenice biti ograničeno, što će se nepovoljno odraziti na prinos useva.

Karcinom debelog creva ili kolorektalni karcinom, predstavlja treći najčešći maligni tumor i kod muškaraca i kod žena u razvijenim zemljama, kao i treći najčešći uzrok smrti ulsed malignog oboljenja. Uprkos napretku u hirurškom lečenju i uvođenju kombinovanih terapijskih modaliteta, 5-ogodišnje preživljavanje retko prelazi 60%, i kreće se između 90% kod lokalizovane bolesti do 11% u slučajevima diseminovanog oboljenja. U 55%-80% pacijenata će doći do pojave recidiva, sa inicijalnom pojavom izolovanih metastaza u jetri u oko 30% pacijenata. Metastaze u jetri upravo predstavljaju vodeći uzrok morbiditeta i mortaliteta u obolelih od kolorektalnog karcinoma. Pozitronska emisiona tomografija sa kompjuterizovanom tomografijom sa primenom fluoro-deoksiglukoze (FDG PET/CT) predstavlja naprednu dijagnostičku metodu u detekciji loko-regionnlanih recidiva i udaljenih metastaza kod pacijenata nakon operacije primarnog kolorektalnog karcinoma, zahvaljujući visokoj senzitivnosti i specifičnosti. Uprkos tome, pojedini autori su prikazali nižu osetljivost i specifičnost FDG PET/CT u poređenju sa multi-detektorskom kompjuterizovanom tomografijom (MDCT) i magnetnom rezonancom (MR) u detekciji metastaza u jetri. Trenutne preporuke za praćenje pacijenata nakon operacije kolorektalnog karcinoma predstavljaju određivanje serumske koncentracije karcino-embrionog antigena (CEA) i vizualizacione dijagnostičke metode. CEA, iako osetljiv u detekciji ranog relapsa, često daje lažno-pozitivne nalaze. Uloga karbohidratnog-antigena 19-9 (CA 19-9) u detekciji rekurentnog kolorektalnog karcinoma je još uvek nejasna, iako postoje studije koje naglašavaju njegov potencijalni prognostički značaj. Za razliku od MDCT i MR koji koriste anatomske parametre (veličinu lezije) radi evaluacije terapijskog odgovora, FDG PET/CT kvantifikuje funkcionalne, metaboličke promene, koje su bolji prediktor ishoda prema pojedinim autorima. Produžavanje preživljavanja se može postići identifikacijom visoko-rizičnih pacij, Colorectal carcinoma represents the third most common malignant tumor in both men and women in developed world and the third leading cause of cancer-related death [1]. Despite the advances in surgical treatment and introduction of combined therapeutical modalities, 5 years survival rarely exceeds 60%, varying from 90% in localized disease to 11% in patients with spread to distant organs. Between 55% and 80% of patients will develop recurrence, with isolated hepatic recurrence initially occuring in approximately 30% of patients. Overall, liver metastases represent leading cause of cancer-related morbidity and mortality in colorectal cancer. At present, whole-body fluorine-18-fluoro-deoxyglucose positron emission tomography/computed tomography (FDG PET/CT) is an advanced diagnostic imaging technique in detecting loco-regional recurrence and metastases in postoperative patients with colorectal carcinoma for its higher sensitivity and specificity. However, other authors reported on lower sensitivity and specificity of FDG PET/CT compared to multi-detector computerized tomography (MDCT) and magnetic resonance imaging (MR) in detection of liver metastases. Current guidelines for managing patients with CRC after therapy recommend regular measurements of serum carcinoembryogenic antigen (CEA) and imaging tests. CEA, although sensitive in detecting early relapse, gives very often a false-positive result. The role of carbohydrate antigen 19-9 (CA 19-9) in detection of recurrent CRC is still unclear, although there have been studies suggesting its potential prognostic significance. In contrast to MDCT and MR, which use anatomic parameters (lesion size) to evaluate therapy outcome, FDG PET/CT quantifies functional change, a better predictor to disease development according to some authors. The improvement of survival in patients with colorectal carcinoma could be achieved by the identification of high risk patients for disease recurrence and progression, as well as for the clas

Crucial influence on the outcome of radioiodine therapy (RIT) in Graves’ hyperthyroidism (GH) has the effective half-life of 131I in the gland. The short-term treatment with Lithium carbonate (LiCO3) enhances the 131I half-life and increase the thyroid radiation dose. The aim of this study was to assess the efficacy of RIT combined with LiCO3 in patients with GH. This prospective study included 30 patients treated with 131I-NaI in combination with LiCO3 (RI-Li group), and 30 patients treated only with 131I-NaI (RI group). Treatment with LiCO3 (daily dose of 900 mg) was started one day before RIT and continued six days after. Results: In RI-Li group the serum level of Li was 0.571±0.156 μmol/l at RIT. Despite of significantly increased serum TT4 and FT4 levels, and decreased TSH level in RI group, there were no considerable changes in hormone levels in RI-Li group 7 days after treatment. The successful therapy outcome (euthyroidism or hypothyroidism) was registered in 73.3% of patients from RI and in 90.0% of patients from RI-Li group (p<0.01). Lithium treated patients were cured faster (27 of 30 patients were cured after one month) than those treated only with 131I (12 patients were cured after one and 22 patients after 12 months). The presence of euthyroidism gradually decreased while the presence of hypothyroidism increased in lithium-treated patients, and contrary to RI group not all cured patients were hypothyroid at the end of the study. There were no toxic effects of LiCO3 during 7 days treatment. Conclusions: Presented results showed beneficial influence of short-term treatment of LiCO3 on RIT outcome. Lithium-treated cured patients slowly achieved hypothyroidism in comparison to patients treated with 131I alone, and not all of them were hypothyroid after one year. Also, lithium prevented a significant increase of TT4 and FT4 in serum seven days after RIT.

Introduction Coronary heart disease takes the first place in morbidity and mortality worldwide. As this disease increasingly affects younger people, especially in underdeveloped and developing countries, great efforts are being made aimed at prevention, early detection and treatment of coronary artery disease (CAD). Prevention of coronary heart disease is aimed at modifying risk factors such as obesity, physical inactivity, diabetes, and smoking tobacco, the role of which in the pathogenesis of this disease has unequivocally been proven. On the other hand, the diagnosis of coronary artery disease increasingly involves different methods of imaging in medical diagnostics, while percutaneous interventions are more oriented towards the therapy in terms of eliminating the causes of myocardial ischemia due to stenosis or occlusion of the coronary arteries. Myocardial perfusion scintigraphy with single photon emission tomography is non-invasive nuclear medicine diagnostic method by means of which it is possible to determine the possible existence of ischemic changes in the myocardium of the left ventricle, resulting from the existence of stenosis or occlusion of the coronary arteries in patients with existing symptoms, and in asymptomatic patients with existing risk factors. Aim The aim of this study was to estimate diagnostic accuracy of myocardial perfusion scintigraphy with single photon emission tomography in early detection of coronary artery disease in four groups of patients: the patients suspected of the existence of ischemic heart disease at moderate risk of existence of coronary artery disease without previous history; the patients suffering from diabetes mellitus at moderate risk of existence of ischemic heart disease without previous history of coronary artery disease; the patients who underwent non-surgical methods of treatment of coronary artery disease by means of transluminal percutaneous approach; and the patients who underwent surgical method of treatment