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Additive manufacturing, as a production technology and a scientific field, offers a lot of potential for new research, attracts the attention and interest of manufacturing companies and the academic community. With a new approach in product design, a digital connection chain, and the possibility of producing final products with complex configurations, it has significant advantages in relation to conventional production. However, the initial investment and production costs make this technology still inaccessible to a certain number of users, with the tendency for this to change. In this sense, great attention has been paid to additive manufacturing planning, cost analysis and the possibility of optimizing structural and process parameters of production and processes. This paper is intended to explain, in a clear and concise manner, the basic assumptions of the technology, its advantages and certain disadvantages, ongoing and future trends in development as well as current areas of research (cost estimation, multi criteria decision making (MCDM), topology optimization) and applied methods and concepts. The authors believe that this paper will provide additional help in process planning for additive manufacturing as well as promote the necessity for introducing and application of different optimization techniques when designing technology for additive manufacturing.

Introduction Marginal seal or adequate marginal adaptation of material along the cavity walls should be able to prevent leakage of tissue fluid and consequently bacterial microleakage, terefore, it is considered as significant factor for long term success of endodontic treatment. The aim of this work was to test the marginal microleakage of newly synthesized nanostructured biomaterials based on calcium aluminate, calcium silicate and MTA with a dye penetration test after application the material to the interradicular perforations of extracted teeth. Material and method The study included 48 extracted human maxillary and mandibular molars. Newly synthesized nanostructured materials were tested: material based on calcium aluminate, calcium silicate. Commercial calcium silicate cement (MTA Angelus, Londrina, Brazil) was used as a control material. Marginal microleakage was examined with a dye penetration test six months after application of the material in experimentally prepared interradicular perforations on extracted human molars. Penetration depth measurement was analyzed with a binocular magnifier (Leica DM 500, Leica Byosistems). Results are expressed in millimeters and statistically processed by applying the analysis of variance for repeated measurements with the Sidak test. Results The lowest average penetration (mm) was for MTA (1.40 ± 0.63 mm), and the highest for Ca aluminates (2.10 ± 0.63 mm), while for calcium silicates an average color penetration of 1.73 ± 0, 67mm was recorded. By testing intergroup differences in color penetration between groups, a statistically significant difference between MTA and Ca aluminate was obtained using Sidak's test (t = -0.693; p = 0.036). No statistically significant difference was recorded between MTA and Ca silicate, nor was there a statistically significant difference between Ca aluminate and Ca silicate. Conclusion The lowest marginal microleakage, the best marginal sealing, was recorded with the MTA material. The microleakage of calcium aluminate-based materials was significantly higher compared to calcium silicate and MTA.

Introduction In addition to good biological properties, biomaterials should also possess appropriate physical properties in order to provide stability and longevity at the place of application. The aim of this work was to evaluate physical properties of an experimental nanostructured material based on calcium aluminate (CAL) and calcium silicate (CS). Material and method The research used nanostructured calcium aluminate synthesized by the hydrothermal solgel method from the individual components of calcium aluminate (CaO·Al2 O3 ), calcite (CaCO3 ) and barium sulfate (BaSO4 ) as an X-ray contrast agent and calcium silicate (CS). The prepared material was placed in plastic molds with a diameter of 5 ± 0.1 mm and a height of 2 ± 0.1 mm. After setting time, the materials were left in an incubator at 37°C for 24 hours, and then they were removed from the mold and absorption and solubility of the materials was calculated. MTA (Angelus Londrina, Brazil) was used as a control material. Results The lowest material solubility was recorded with MTA (0.255 mg/mm3 ), followed by calcium silicate (0.267 mg/mm3 ), and the highest with calcium aluminate (0.725 mg/mm3 ). The difference was statistically significant between calcium aluminate and MTA (p = 0.001901) and between calcium aluminate and calcium silicate (p = 0.002550). After 28 days in deionized water, the lowest water sorption was recorded with MTA (0.347 mg/mm3 ), followed by calcium silicate (0.357 mg/mm3 ), and the highest water sorption was measured with calcium aluminate (0.474 mg/mm3 ). Statistically significant differences were observed between calcium aluminate and MTA (p = 0.000283) and between calcium aluminate and calcium silicate (p = 0.001576). Conclusion Material solubility and water absorption of calcium aluminate-based nanostructured material was significantly higher compared to calcium silicate (CS) and MTA.

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Lemon fruits are an important source of vitamin C, potassium, folate, carotenoids, polyphenols, coumarins and terpenes. These lemon compounds have antioxidant and anti-inflammatory properties which have beneficial effects on human health. This research aimed to elucidate the etiology of blue and green molds detected on lemon fruits in Serbia. Using integrative identification approach, the obtained isolates were characterized from morphological, physiological, molecular, phylogenetic and pathological aspects. Colony growth and morphology were examined on Czapek yeast autolysate agar (CYA), Malt extract agar (MEA) and Creatine sucrose agar (CREA), and on CYA at two additional incubation temperatures (5 and 37 °C). For molecular identification, ITS and partial β-tubulin (BenA) genes were sequenced. Phylogenetic relationships were investigated using maximum-likelihood method. A pathogenicity test was carried out and the possible difference in pathogenicity among isolates was assessed with analysis of variance (ANOVA) and subsequent Tukey’s test. Four species were identified: Penicillium expansum, Penicillium digitatum, Penicillium polonicum and Talaromyces rugulosus. All four species proved to be pathogenic on lemon fruits, producing symptoms similar to those observed on naturally infected fruits. The results of this study are the first records of the beforementioned Penicillium/ Talaromyces species as postharvest pathogens on lemon fruits in Serbia and the first world report of T. rugulosus as phytopathogenic on the same host.

Introduction ALBO-HA (Vinca, Serbia) is new nanostructured calcium aluminate cement, synthesized as a potential alternative to mineral trioxide aggregate (MTA). The purpose of this study was to compare the periapical tissue response to new nanostructured calcium aluminate cement ALBO-HA with white MTA (MTA Angelus, Londrina, Brasil) as root-filling material into the root canal of sheep' s teeth. Material and methods Sixteen mandibular incisors from two 24-month-old sheep were used. Root canals were pre pared and filled with ALBO-HA (group 1) or MTA (group 2) (eight teeth per group in each sheep). After four weeks the animals were sacrificed, teeth with surrounding tissue removed, and histologically processed. The sections were analyzed for determination of scores of the following parameters: periapical inflammatory infiltrate, newly mineralized apically formed tissue, apical periodontal ligament space thickness and resorption of dentin, cementum and bone. Data were analyzed statistically (a=0.05) using Mann-Whitney U test. Results Slight inflammatory infiltrate was observed in 75.0% and 62.5% of samples in the group 1 and group 2, respectively (p>0.05). Partial newly mineralized apically formed tissue was found in 75.0% of samples in the group 1, and 87.5% of samples in group 2 (p>0.05). No significant difference was noted for periodontal ligament space thickness (p>0.05). Resorption of dentin, cementum or bone was not observed. Conclusion ALBO-HA and white MTA Angelus had a similar effect on inflammation, newly mineralized apical tissue formation and thickness of periodontal ligament space after root canal filling under the present experimental conditions.

New trends in technological systems in terms of processing processes have also placed new demands on the measuring technique. The application of conventional metrology systems and the procedures that support them have become a limiting factor in terms of flexibility and measurement accuracy. The main problem problem is the rapid metrological identification of complex metrological tasks, such as, for example, shape and position tolerances for parts of medium and high accuracy. In addition to metrological identification, the problem is also the connection of metrological databases, which has a direct impact on the obtain results accuracy. In order to solve these problems, this paper presents an approach to modeling a digital measuring twin based on a numerically controlled measuring machine. In a broader sense, the developed model integrates machine and computer technologies and was applied in the field of metrology, that is, the examination of achieved tolerances on machine parts using CMM. The benefits are reflected in the fact that it is not necessary to construct expensive prototypes, it saves time, avoids collision and the most important thing in the world of industry, it saves money.

Numerous technological solutions in recent years have significantly improved the cleaning and shaping of canals and made canal instrumentation simpler, more efficient and safer. Significantly faster and less stressful canal instrumentation for the therapist is enabled by the specific design of the file working part and a special thermal modification of NiTi alloy with a change in the movement dynamics of the file in the canal. Research has shown that the problem of cyclic fatigue and torsional stress of the file during canal preparation can be solved by changing usual continuous rotation of the file. Dental technology has introduced the technique of reciprocal movements as an alternative to full file rotation. This change in file rotation direction during instrumentation, based on the technique of balanced forces, significantly reduces contact surface with the canal wall, eliminates the effect of screwing, extends the life of the file and further increases safety of instrumentation of different canal systems. An important advantage of changing the usual dynamics of file movements is that the concept of reciprocal movements is based on the use of only one file, which in addition to shortening treatment time also makes this intervention safer and with significantly lower percentage of defects and fractures of NiTi files. The aim of this paper was to present the concept of canal instrumentation with NiTi files with reciprocal movements as well as development, properties and possibility of application of these files in different clinical situations.

The application of irrigating solutions is essential in chemomechanical treatment of tooth root canal. However, chemical and electrochemical aggressiveness of the solutions, which directly act on instruments, may damage their surface. The aim of this study was to investigate the sensitivity of the nickel-titanium (Ni-Ti) and stainless steel endodontic files to corrosive action of the sodium hypochlorite (NaOCl), chlorhexidine gluconate (CHX) and ethylenediamine tetraacetic acid (EDTA). Testing of sensitivity to corrosion of the instruments was performed by dynamic potentiometric method. Measurements were made in 5.25% NaOCl, 0.2% CHX and 17% EDTA. Ni-Ti instruments immersed in 5.25% NaOCl showed the most intensive corrosive changes and the lowest value of pitting potential of 1.1V. Stainless steel instruments immersed in 5.25% NaOCl showed higher value of pitting potential of 1.5V. Stainless steel instruments immersed in 0.2% CHX showed lower corrosive surface changes and higher value of pitting potential of 1.6V, whereas Ni-Ti instruments immersed in 0.2% CHX showed the pitting potential of 1.9V. The corrosion was not observed in both types of instruments after immersion in 17% EDTA. The use of 5.25% NaOCl and 0.2% CHX may cause severe surface corrosion of Ni-Ti and stainless steel endodontic files. [Projekat Ministarstva nauke Republike Srbije, br. 175102]

An artillery projectile in flight produces a low pressure area immediately behind the projectile which creates a force called base drag which lessens the velocity of the projectile. It is known that theoretically this base resistance can be reduced or even eliminated by allowing a stream of hot gas to flow out of the base surface of the projectile in a suitable manner. The effect produced by this stream of hot gas is called base-bleed effect. The internal ballistic calculation of existing base bleed configuration is presented in the paper. A numerical simulation of axisymmetric body projectiles was obtained with the Reynolds Averaged Navier-Stokes (RANS) computational fluid dynamics software (CFD). Also, two turbulence models were tested and validated with the semi empirical prediction. The realizable k-ɛ turbulence model was chosen for calculation of aerodynamic drag of the projectile with and without base bleed effect. Computed result show a drag reduction with base bleed of about 12% in supersonic flow regime.

Introduction Direct pulp capping is an important therapeutic method that has goal to provide formation of dentin bridge and healing process of the pulp. The aim of this study was to investigate the effects of new nanostructural materials based on calcium silicate systems and hydroxyapatite on exposed dental pulp in Vietnamese pigs. Material and Methods The study was conducted on 30 teeth of two Vietnamese pigs (Sus scrofa verus). On buccal surfaces of incisors, canines and first premolars, class V cavities were prepared with a small round bur and pulp horn was exposed. In the first experimental group (10 teeth) the perforation was covered with new nanostructural material based on calcium silicate systems (CS). In the second experimental group, the perforation was covered with compound of calcium silicate systems and hydroxyapatite (HA-CS) (10 teeth). In the control group, exposed pulp was covered with Pro Root MTA® (Dentsply Tulsa Dental, Johnson City, TN, USA) (10 teeth). All cavities were restored with glass ionomer cement (GC Fuji VIII, GC Corporation, Tokyo, Japan). Observation period was 28 days. After sacrificing the animals, histological preparations were done to analyze the presence of dentin bridge, inflammatory reaction of the pulp, pulp tissue reorganization and the presence of bacteria. Results Dentin bridge was observed in all teeth (experimental and control groups). Inflammation of the pulp was mild to moderate in all groups. Neoangiogenesis and many odontoblast like cells responsible for dentin bridge formation were detected. Necrosis was not observed in any case, neither the presence of Gram-positive bacteria in the pulp. Conclusion Histological analysis indicated favorable therapeutic effects of new nanostructural materials based on calcium silicate systems and hydroxyapatite for direct pulp capping in teeth of Vietnamese pigs.

Introduction. Although many studies have reported various advantages of nickel-titanium endodontic instruments, the use of stainless steel endodontic files still presents a standard in everyday practice. The aim of this study was to evaluate ultrastructure of the surface of stainless steel endodontic instruments before and after their use. Material and Methods. Fourteen sets of non-used stainless steel endodontic reamers and files were included in the study. Each set of instruments was used one, three or six times in simulated clinical conditions on extracted maxillary premolars. After their use the instruments were subjected to cleaning and sterilization procedures. Ultrastructure of the surface of instruments was observed under scanning electron microscope (SEM). Surface analysis was performed based on the number of uses and size of instruments. The following characteristics were analyzed: defects of instrument flutes, defects of cutting edges and instrument deformations. Results. SEM analysis showed defects on the surface of non-used instruments as a result of the manufacturing process. Surface defects, defects of cutting edges as well as flutes deformations were observed after a single use and were more often noticed in small sized instruments. After three uses, flutes deformations were observed in all small sized instruments and some of the medium size. After six uses all groups of instruments showed defects of cutting edges. Conclusion. Non-used stainless steel endodontic instruments showed surface defects created by the manufacturing process. Defects of cutting edges and flutes can be observed after a single use. To minimize complications and mistakes during clinical preparation it is recommended to limit the number of instrument uses.

Introduction. Direct pulp capping is therapeutic method of applying medication on exposed pulp in order to allow bridge formation and healing process. The aim of this study was to investigate the effect of Biodentine on exposed dental pulp of Vietnamese pigs. Material and Methods. The study was conducted on 20 teeth of Vietnamese pigs (Sus scrofa domesticus). On buccal surfaces of incisors, canines and first premolars, class V cavities were prepared and pulp was exposed. In the experimental group (six incisors, two canines and two premolars) the perforation was covered with Biodentine® (Septodont, Saint-Maur-des-Fosses, France). In the control group, the perforation was covered with MTA® (Dentsply Tulsa Dental, Johnson City, TN, USA). All cavities were restored with glass ionomer cement (GC Fuji VIII, GC Corporation, Tokyo, Japan). Observation period was 28 days. After sacrificing the animals, histological preparations were done to analyze the presence of dentin bridge, an inflammatory reaction of the pulp, pulp tissue reorganization and the presence of bacteria. Results. Dentin bridge was observed in all teeth (experimental and control groups). Inflammation of the pulp was mild to moderate in both groups. Neoangiogenesis and many odontoblast like cells responsible for dentin bridge formation were detected. Necrosis was not observed in any case, neither the presence of Gram-positive bacteria in the pulp. Conclusion. Histological analysis indicated favorable therapeutic effects of Biodentine for direct pulp capping in teeth of Vietnamese pigs. Findings were similar with Biodentine and MTA.

Introduction. Mineral trioxide aggregate (MTA) is one of the most commonly used materials in endodontics. Given its shortcomings, there is an intensive search for new materials. Calcium-silicate phase (CS phase) is a new material synthesized by the method based on a combination of sol-gel process and self-propagation synthesis which can significantly improve setting time through accelerated hydration. The aim of this study was to explain the mechanisms of hardening of CS phase in aqueous medium as similar mechanism is expected in contact with body fluids. Materials and Methods. CS phases Ca3SiO5 (C3S) and 2β-CaSiO4 (β-C2S) were synthesized from CaCl2•5H2O (Merck, Germany). To investigate the process of hydration, CS were mixed with water and kept at 37 °C for 28 days in closed polyethylene containers. Analysis of the composition of samples before and after immersion in water for 1, 3, 7 and 28 days was performed using X - ray diffractometry and IR. Results. XRD patterns for hydrated samples during 1, 3, 7 and 28 days showed that the amount of hydrated tobermorite phases relative to the amount of CS phase changes with the time of hydration. After 1 day, in addition to the hydrated phases, a significant amount of untransformed β-C2S and C3S were found while after 28 days hydrated CS phase was completely transformed to tobermorite with a small amount of portlandite. Conclusion. Using combined method of sol-gel and self-propagating waves at high temperature very active nanostructured silicate phases were obtained. Hydration process of CS phases was analyzed using XRD and FTIR, the mechanism of hydration was proposed and it was pointed to the difficulties in determining the exact reaction as well as the problem of determining the exact structure of tobermorite. [Projekat Ministarstva nauke Republike Srbije, br. 172026]

Introduction. Health care, as one of the most important and sensitive fields of human endeavour, has a significant social impact; therefore changes in this area have wide implications on society in general. The latest economic crisis resulted in slow growth of gross domestic product (GDP), high unemployment rates, low living standards, and increased poverty across the globe. This includes decreased capacity of health system, and reduced quality and supply of health services. The aim of the study was to explore possible impact of the current world economic crisis on the public health sector workforce in Serbia. Materials and Methods. The study was conducted as retrospective analyses of the Public Health Institute (PHI) human resource data, the Republic Statistical Office publications and database, the Republic Development Bureau report, as well as the analysis of healthcare expenditures obtained from the Chamber of Health Institutions reports. The comparative analytical method was used for the assessment of socio-economic and human resource indicators over the period of five years, 2006 to 2010. Results. Results showed that the world economic crisis discontinued steady economic growth in Serbia. Between 2006 and 2008, the real GDP growth rate has been fluctuating between 3.6% and 5.4 %, while in 2009 it had negative growth rate of -3.1 % and slight increase in 2010 of 1.0%. In 2006, the GDP per capita was US$ 3,943, and by 2008 it almost doubled reaching US$ 6,498, while in 2009 it fell down to US$ 5,499, and continued decrease in 2010 to US$ 5,006. In 2007, the overall inflation rate was 6.5%, and after fluctuaion between 11.7% in 2008 and 8.4% in 2009 it droped again to 6.5% in 2010. According to the PHI, from 2006 to 2008 there was steady increase of full-time employees in the public health care sector; from 108,975 in 2006 to 114,317 in 2008. In 2009, the number of full-time employees slightly declined to 114,175 and 114,432 in 2010. There was constant increase in total number of employees in the public health care sector, from 125,081 in 2006 to 129,357 in 2008. In 2009, the total number of employees decreased to 128,694 and in 2010 to 122,695. At the same time, the total expenditure of human resources in the health sector as the percentage of total health expenditure declined from 37.7% in 2006 to 34.7% in 2010. The public health sector salaries after steady increase from 59.9% of total health expenditure in 2006 to 61.2% in 2007 and 2008, decreased to 56.2% in 2010. The unemployment rate for medical doctors almost doubled in 2010 as compared to 2006. Conclusion. Preliminary study results showed that the world economic crisis had negative impact not only on GDP growth rate, the inflation and unemployment rate, but on the public health sector workforce, their salaries and unemployment rate in Serbia.

Introduction. As the part of research on costs in the health care system, there is a growing interest in the world for the estimating costs for the treatment of disease. This value represents the burden that a particular disease or group of diseases puts on the society. Until the year 2000, when the Organization for Economic Countries Development (OECD) established a System of Health Accounts (SHA), there was not even approximate methodological guide for calculating the cost of the disease. The aim of this study was to determine the costs of health care in the Republic of Serbia according to the major International Classification of Diseases (ICD-10) and to provide a comparative cost analysis for the treatment of diseases in the period from 2004 to 2009. Material and Methods. A retrospective and comparative analysis of health statistics from the database of the Institute of Public Health of Serbia and financial information provided by the Health Insurance Fund in the period 2004-2009 was performed. Financial information and data on hospital services, outpatient, home health care, ancillary health care services, drug consumption and consumer goods in healthcare were analyzed using SHA methodology. Results. Results showed that during the observation period, the maximum cost of health care in Serbia by main classification of ICD-10 was achieved in 2009 and it was RSD 144,150,456,906.00 (€ 1,503,321,134; $ 2,160,253,219) and the minimal cost was achieved in 2004 - the amount being RSD 49,546,211,470.00 (€ 628,086,723; $ 855,203,134). Results showed that in 2004 the highest costs were allocated to circulatory diseases (18.98%), followed by neoplasm (11.12%), and lowest for congenital anomalies (0.64%). In 2009, the highest costs were allocated to circulatory diseases (18.87%), infectious and parasitic diseases (11.20%), diseases of digestive system (9.26%) nervous system diseases (9.20%), and neoplasm (8.88%), whereas the minimal funds were allocated for congenital anomalies (0.33%). Conclusion. Comparative analysis showed that the value of overall spending in healthcare increased three times in 2009 as compared to 2004.

The paper points out to the differences of the First order theory and Second order theory and of the significance in practical calculations. The paper presents theoretical foundations and expressions of calculations of impacts on the stability of structure, that is, review of the Second order theory in a bridge with members semi-rigid connections in joints. In the real structures in general and the especially in the prefabricated structures the connection of members in the nodes can be partially rigid which can be very significant for the changes in tension and deformation. If the influence of the normal forces is significant and the structure is slender then it is necessary to carry out a calculation according to the Second order theory because the balance between internal and external forces really established on the deformed configuration and displacements in strict formation are also unreal. The importance and significance of the calculations and distribution of impact according to the Second order theory were presented in numerical examples as well as the calculation of critical load as well as the buckling length of members with semi-rigid connections in joint.

Actual vapor pressure (VP) is an important parameter that is used in many evapotranspiration equations. However, vapor pressure is difficult to measure accurately. In the humid climate, the actual vapor pressure can be derived from minimum air temperature. The objectives of this study were: first, to estimate errors that can arise if VP data are not available and have to be estimated; second, to compare the Priestley-Taylor ET0 values computed under various levels of VP data availability; and third, to evaluate the reliability of Priestley-Taylor equation as compared to the FAO-56 Penman-Monteith method. The following main conclusions can be drawn: Estimated VP values generally were in closest agreement with measured VP values. The measurements of air humidity at humid locations are not indispensable for estimating reference evapotranspiration. The Priestley-Taylor method (with measured or estimated VP) provides the very good agreement with the evapotranspiration obtained by the FAO-56 Penman-Monteith method except windless locations.

Pseudomonas syringae is a widespread and economically important plant pathogen, one found on a number of hosts, including fruit trees, field crops, vegetables, and ornamental plants. This bacterium has been experimentally identified as a parasite of pear, apple, apricot, peach, cherry, sour cherry, plum, and raspberry. The present study was designed to establish differences between strains isolated from fruit trees in Serbia. The pathogenic and biochemical characteristics of isolates were studied. The BOX-PCR method was used to generate genomic fingerprints of Pseudomonas syringae isolates and to identify strains that were previously not distinguishable by other classification methods. Different Bacillus sp. strains were tested for in vitro inhibitory activity against Pseudononas syringae isolates. Bacillus sp. strains show inhibitory activity only against P. syringae isolates that originated from peach. The obtained results demonstrate that the population of the bacterium Pseudomonas syringae from the fruit trees in Serbia is very diverse.

Introduction. A lack of appropriate adhesiveness is one of the biggest problems in the restorative dentistry today and the main cause of the microleakage between restorations and hard dental tissue. The aim of this study was to assess the adhesiveness of two different glass ionomer cement restorations class V on the hard dental tissue using the SEM analysis and dye penetration test. Material and methods. The study included 80 extracted teeth for orthodontic reasons (premolars and molars) in both genders and different age. On the vestibular and oral side of the teeth, adhesive preparations class V were done (size 3Ч2Ч2 mm). On the vestibular preparation, GC Fuji II was applicated and GC Fuji II LC-improved on the oral side. The quality of the adhesiveness between restorations and hard dental tissue was evaluated using the SEM analysis and dye penetration test (0.5% basic fuxsin). Linear penetration of the dye was observed using 10 times magnification. Results. The results showed that microleakage was presented with both materials but a ratio was less with Fuji II LC compared with Fuji II. Also, the microleakage was less on the occlusal parts of the restorations than on the gingival, with both materials. Microleakage was noticed in 93.44% teeth with Fuji II GJC restorations with index of microleakage of 148 on all edges. Fuji II LC GJC restorations showed microleakage in 68.4% teeth with index of microleakage 75 on all edges. The SEM analysis showed that both glass ionomer materials had better adhesiveness to the enamel than to the dentin. The average gap length between Fuji II LC and dentin was 9 μm and Fuji II 17 μm, respectively. Conclusion. Better adhesiveness to the hard dental tissue was achieved with materials of the newer generations, resin modificated glas ionomer cements.

Aim: To evaluate the effect of irrigation techniques, i.e. different types of irrigation needles, on the quality of cleaning of root canal walls using scanning electron microscopy (SEM). Material and Method: The study was conducted on 16 extracted, single-rooted, human teeth. The samples were allocated to two experimental groups depending on the type of the irrigation needle. Conventional needles were used for the irrigation of Group I and laterally perforated ones for Group II. All root canals were instrumented using K files and the Step-back technique. During instrumentation, all samples were irrigated with 2.5 % sodium hypochlorite solution followed by final irrigation with 17 % EDTA for 1 min. After that, all samples were irrigated with 10 ml of distilled water. The roots were, then, sectioned longitudinally and middle one third of each root canal was analyzed using SEM. Quantitative analysis was based on criteria by Hülsmann et al. Results: The obtained results showed that the more efficient removal of debris and the smear layer was accomplished in the group of samples irrigated using laterally perforated needles than conventional needles. The difference between the investigated irrigation techniques were statistically significant (p

In modern timber structures a large number of beams are loaded with bending Contemporary engineering practice has shown that the effect of tangential stress and deflection of beams are not controlled during the design of this kind of beams. This could produce negative consequences in structure behavior during the exploitation. Using optimal design procedure in this article, the member is designed for bending in two planes. The following criteria must be observed: normal bending stress, shear stress and maximal deflection.

Modern methods of root canal cleaning and filing are causing formation of the smear layer on treated surfaces. The aim of this paper was to review clinical aspect of smear layer in endodontics. Smear layer is the consequence of instrumentation of root canal walls and is consisted of organic and inorganic particles of cut dentine, necrotic and/or vital pulp fragments, microorganisms and their products. Existence of smear layer is affecting permeability of the radicular dentine, thus decreasing effects of canal medicaments and impairing adhesion of obturation materials in root canal. Removal of the smear layer from canal walls is possible with use of various chemical agents, ultrasonic or laser techniques. Regardless to contradictory attitudes and opinions, removing the smear layer is required for possible bacterial contamination, compromised effects of root canal medication and in order to obtain better obturation of canals 'system. .

In the modern civil engineering design, especially in the field of machine foundations, the dynamic actions in the form of the impulse load that is short-term, high intensity loads are very frequent. When an acting force during a short time interval remains constant, the impulse is of a rectangular form, as opposed to the trapezoid, triangular, parabolic and sinusoid form, with defined time of increase and decrease of the load. This paper considers the influence of the form of the impact impulse load on the dynamic response of the foundation structure, without changing the remaining parameters.

The purpose of this SEM study was to evaluate the cleaning effects of different manual and mechanical endodontic instruments. Sixty single canal human teeth were selected for this study. The root canals were instrumented by seven types of manual endodontic instruments (K-enlargers, K files Rattail files, K-Flexofiles, K Flex files, Hedstrom and NiTi Flex files) and five different mechanical endodontic instruments (Rispi, Rat tail Hedstrom, NiTi Flex files and K-enlargers). During and after the instrumentation, the canals were irrigated by 2.5% sodium hypochlorit. After splitting the roots longitudinally, the amount of debris and smear layer was quantified on the basis of a numerical evaluation scale, using scanning electron microscope. Results were statistically analysed using the Kruskal-Wallis test and t-test. There were no statistically significant differences between hand instrumentation and machine instrumentation with different endodontic instruments for any of the variables tested. Best instrumentation results in removing the smear layer and dentinal debris from the root canal were obtained with Kerr, NiTi and Hedstrom hand files and with K-enlargers, NiTi and Rat-tail mechanical files. In the apical thirds of root canals prepared using hand and mechanical endodontic instruments the smear layer and dentinal debris were always more abundant when compared with the middle and coronal thirds. In conslusion, cleaning efficacy differed slightly among the techniques and instruments, none of them completely removed smear layer and all left some debris.

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Presented research aimed to develop an alternative approach for the estimation of biosorption capability of sunflower husk. The acid-pretreated sunflower biomass was characterized by scanning electron microscopy combined with energy dispersive X-Ray spectroscopy (SEM-EDX) analysis and Fourier transform infrared (FTIR) spectroscopy. Biosorption efficiency has been evaluated using inductively coupled plasma optical emission spectroscopy (ICP-OES) and laser-induced breakdown spectroscopy (LIBS). The adsorption capacity of the adsorbent was determined as the function of the pH of the solution, the initial concentration of heavy metal solutions, and contact time. The optimal conditions were achieved after 15 min of contact at pH 6, while the percentage of the removal was from 80.0–98.7 %, depending on the element. The results obtained from the kinetic and isotherm studies show that maximum adsorption of ions was quickly reached and followed the pseudo-second-order kinetic model. Real samples were tested and obtained Ni values by LIBS method were 3100±200 and 1240±100 mg kg-1, while estimated values by the ICP-OES were 2995±20 and 1130±10 mg kg-1, respectively. The obtained results prove that LIBS method can be used as a “green alternative” for the evaluation of biosorption efficiency.

Introduction/Objective. of this study is to use scanning electron microscopy (SEM) analysis to examine surfaces of new and same sets of Ni-Ti instruments after canal preparations, to check their suspectability to corrosion. Methods. In this study, we used five different endodontic Ni-Ti instruments: K3, Mtwo, ProTaper Universal, HyFlex and BioRaCe. Instruments were analyzed before and after preparation of canals of different curvature, using SEM (150–2000 ×). Results. Corrosion of the working part was observed in 5.5% of new Ni-Ti instruments of the K3 system (apical and middle segment), in 5.5% of Mtwo instruments (apical third), and in 11.1% of ProTaper Universal systems (apical and middle third). Corrosion was not observed on the new instruments of the HyFlex and BioRaCe kits. After instrumentation, disinfection, and sterilization, corrosion was observed in all sets of K3 and ProTaper Universal systems and in all HyFlex instruments of the first group. Corrosion was observed in the HyFlex system in the second group in 16.7% of instruments (apical and middle third) and in the third 83.3% in the apical and 66.7% in the middle segment. In the Mtwo set, corrosion was observed in 16.7% of instruments in the first (apical and middle third), in the second group in 33.3% of instruments in the apical part and 50% in the middle third, while in the third group, corrosion was observed in 16.7% of instruments in the middle third of instruments. Conclusion. Rotary Ni-Ti instruments K3 and ProTaper Universal are susceptible to corrosion in a very high percentage. Ni-Ti systems with post-heat treatment of the working part (HyFlex) are somewhat more resistant to corrosion, while in Ni-Ti systems with electropolished surface (BioRaCe), corrosion is not observed.

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The paper presents the results of the cleaning process of five different lots of natural alfalfa seeds and five different lots of natural red clover seeds. Natural alfalfa and red clover seeds had 75 % to 77 % purity. The experiment was performed in the seed processing center of the Institute for Forage Crops Kruševac. Seed cleaning is performed on different machines that work on the principle of differences in the physical properties of seeds. Significant parameters that define the quality of seeds after processing on the cleaning equipment are the amount of pure seed, weed seed, the seed of other crops, inert matter, amount of pure processed seed, seed losses and processing output. The obtained results enable the correct adjustment of the equipment for the seed processing, depending on the amount and type of weeds and other impurities found in the natural seed of alfalfa and red clover.

Introduction/Objective. Lead exposure represents one of the most important factors that affect the general health, including oral health and it is associated with enamel and dentin tooth defects. The aim of this paper was to determine expression of the fibronectin in the pulp of rats with experimentally induced diabetes mellitus (DM), after lead exposure, by using immunohistochemical analysis. Methods. The study was conducted on 42 rats of Wistar strain. Intoxication of rats with lead-acetate was done via drinking water ad libitum. The first group (Exp_14) consisted of 16 rats, which received lead in water for 14 days, the second group (Exp_30) consisted of 16 rats which received lead in water for 30 days at the same concentration (1500 ppm), while the control consisted of 10 healthy rats. Groups Exp_14 and Exp_30 were induced into DM, by using the Alloxan intraperitoneally. Pathohistological and immunohistochemical analysis determined fibronectin expression in pulp, odontoblasts, predentin and dentine of the teeth. Results. High diffuse positivity of fibronectin in group Exp_14 was noticed in 63.6% of rats, in group Exp_30 in 24% of rats, while in the control group it was noticed in 50% of rats. There was no statistically significant difference in the expression of fibronectin between the examined groups. Conclusion. Lead intoxication through drinking water, for a period of 14 and 30 days, had effect on the expression of fibronectin in the pulp, odontoblasts, predentin and dentin of the teeth of animals experimentally induced DM.

Mandarin fruits are one of the most popular among the Citrus genus. They are consumed because of their nutritional and health benefits, as well as pleasant taste and smell. This paper describes the identification and characterization of Penicillium expansum, isolated from molded mandarin fruits. The obtained isolates were cultivated on five media [Czapek Yeast Autolysate agar (CYA), MEA (Malt extract agar), Creatine sucrose agar (CREA), Yeast extract sucrose agar (YES), and Oatmeal agar (OA)] and at five different incubation temperatures (5, 15, 25, 30, and 37 °C). Isolates were sequenced for two molecular loci: internal transcribed spacer and beta-tubulin. Based on the results from morphological, physiological, molecular, and phylogenetic analyses, the recovered isolates were identified as P. expansum. The isolated species was confirmed as pathogenic to mandarin fruits in a pathogenicity test. To the best of our knowledge, this is the first report of P. expansum as a postharvest pathogen of mandarin fruit in Serbia.

In this paper viruses are considered as very efficient nano-machines that produce numerous copies of them. Observing these nano-architectures, the question arises: which molecular forces and processes make up the set of such structures, given that they are extremely inspiring for development of new technologies at the nano level. There is a need for deep understanding of individual molecular building blocks and their structures, properties of their assemblies and dynamic behavior.

Backgraund/Aim. Primary anti-neutrophil cytoplasmatic antibody (ANCA)-associated vasculitis are chronic multisystemic autoimmune diseases which include microscopic polyangitis (MPA), granulomatosis with polyangitis (WG), eosinophilic granulomatosis with polyangitis (EPGA; churg-strauss syndrome – CSS), and also a localized forms of ill-ness. In our research, we studied clinical and serological parameters in patients, in order to find out which of them would be the best predictor of renal outcome in ANCA-associated vasculitis. Methods. Data from 42 patients with diagnose of MPA (9), WG (17), EPGA (0), CSS (0), and al-so idiopathic rapidly progressive glomerulonephritis (ROEB) without immune deposits (renal-limited vasculitis – 16) were analyzed. Cockroft formula was used for calculating the glomerular filtration in the moment of presenting the illness, and also after five year follow-up period. Other factors that were analyzed are: gender, age, type of ANCA antibodies, type of infections, stage of chronic kidney dis-ease, need for heamodialysis and mortality. Results. Of a total of 42 patients, 17 (40.48%) were male. The average age of the patients at the time of diagnosis was 57.8 (± 10.44) years. Seventeen patients (40.48%) had a diagnosis of WG, 9 (21.43%) MPA, and 16 (38.09%) iRPGN. The presence of positive anti-proteinase (anti-PR3) antibodies was confirmed i n 1 8 patients, a nd a nti-MPO antibodies in 17 patients. Three patients had both subtypes of ANCA antibodies (anti-PR3 and anti-MPO). Initially, 12 patients required heamodialysis treatment. Twenty nine patients had a complete and 13 patients had partial remission. Out of the total number of patients, 8 patients (19.04%) developed the terminal renal failure stage, and ended up on a chronic dialysis program. During a five-year follow-up period, 12 patients (28.57%) resulted in death. The age of the patient proved to be statistically significant predictor of glomerular filtration rate (GFR) at the moment of presentation of the disease (p = 0.011). GFR t = 0 was statistically significant (p = 0.000) for the evaluation of kidney function outcomes in ANCA-associated glomerulonephritis. Conclusion. Kidney function in the moment of illness presentation, determined by GFR t = 0, is the most important significant factor for predicting renal outcome in ANCA-associated vasculitis, and also the mortality in these patients.

More certain therapeutic and significantly facilitated solution of everyday endodontic problems are provided by the introduction of NiTi rotary files in endodontic practice and their proper application. However, their widespread use has caused more and more frequent fractures and has become a significant frustrating factor that diminishes their numerous benefits. Torsional stress and cyclic fatigue are the main reasons for the occurrence of a fracture, and the frequency of NiTi file fractures is exactly proportional to the degree of bending of the canal, knowledge of the features of the file, ie. the skill and expertise of the therapist. The most dominant factor for the occurrence of fractures is the dentist who, in addition to manual dexterity, must have a good knowledge of the anatomy of various canal systems and file design in order to make the best choice for each individual case. Properly formed access cavity and knowledge of the working part of NiTi files enable maximum realization of endodontic skills, increased efficiency of intervention and reduced possibility of error during canal instrumentation. The special treatment of NiTi alloy and new solutions related to the design of the working part have significantly increased file flexibility and resistance to cyclic fatigue. Specific design (reduced number of threads, change of conicity, interruption of blade continuity), reduced engagement of file, ie. change of dynamics of movement in the canal (full rotation, reciprocal, eccentric, transaxial), as well as reduced number of processing files, have also significantly influenced the reduction of fracture risks. The aim of this paper was to analyze the most common reasons for the fracture of NiTi files and emphasize measures and factors that can increase their safe use and reduce complications during canal instrumentation.

Introduction This review aims to investigate modern methods of applying artificial intelligence to diagnose SARS Cov-2 and predict the development of potential emergencies. Methods The most commonly used electronic databases, such as Scopus and Medline during 2020, were searched. A narrative approach was used to synthesize the extracted data. Results In this review paper, it has been shown that the application of artificial intelligence plays a significant role in virus diagnosis and prognosis in clinical trials. It allows resources to be used much more rationally, such as respirators , in hospitals, during the treatment of SARS Cov-2 and the prediction of possible mortality. The obtained results are from the analysis performed on 120 papers and studies that were electronically taken from papers published on Scopus and Pub Med line. Most commonly used artificial intelligence techniques are convolutional neural networks and machine learning. Conclusions Included studies showed that artificial intelligence can significantly improve the treatment of SARS Cov-2, although many of the proposed methods have not yet been clinically accepted. In addition, more effort is needed to develop standardized reporting protocols or guidelines on applying artificial intelligence into conventional clinical practice. This technology is suitable for fast and accurate diagnosis, prediction and monitoring of current patients and prognosis of disease development in future patients.

Introduction: The nutcracker syndrome is a rare clinical entity caused by compression of the left renal vein by the superior mesenteric artery. Epidemiologically opposite, IgA nephropathy is the most common cause of idiopathic glomerulonephritis. A combination of the two diseases has previously been reported in a few cases. Case Report: Herein we report a case of a 22-year-old male patient admitted because of macroscopic hematuria due to excessive oral anticoagulation. He had prior evidence of proteinuria, microhematuria, impaired kidney function, and enlarged left kidney. He presented with fatigue, abdominal pain, nausea, and several instances of vomiting after a meal. A diagnosis of left renal vein compression and IgA nephropathy was made based on clinical, laboratory, radiological findings and kidney biopsy. The vascular anomaly was treated conservatively, while steroids were given to treat glomerulonephritis. The result was complete regression of symptoms, normal laboratory findings, and a significant drop in proteinuria. Conclusion: It is important to evaluate whether patients have nutcracker phenomenon before initiating treatment for IgA nephropathy and vice versa, as hematuria and proteinuria can be overlapping symptoms of both conditions. Renal biopsy should not be hesitated for differential diagnosis, and treatment should be highly individualized.

Introduction/Objective. Irrigation has an important role in root canal cleaning and its efficiency depends on the type of irrigants, the amount, the technique and the irrigation protocol. The aim of this work was to estimate the efficiency of cleaning of the canal walls by using scanning electron microscope analysis after the instrumentation by rotary NiTi instruments with the use of three different irrigation solutions and two final irrigation protocols. Methods. Sixty extracted human incisors were divided into two groups after the rotary instrumentation with the iRace instruments. In both groups, the same amount (1.5 ml) of three solutions (2% sodium hypochlorite solution, 2% chlorhexidine solution, and 10% citric acid solution) and total final irrigation time (90 seconds) was the same. The final irrigation in the first group was accomplished using the technique of continuous irrigation and in the second group it was done using the intermittent protocol. The roots were cut longitudinally and analyzed by thirds (coronal, middle, and apical) on a scanning electron microscope (JSM 6460LV, JEOL Ltd., Tokyo, Japan) with 1,000× magnification. Results. The most efficient cleaning of the root canal walls in both groups was seen after the use of citric acid with the intermittent protocol of the final irrigation (90.7% clean walls), while the least efficient was the final irrigation by chlorhexidine with continuous irrigation (80.3%). The most efficient cleaning of the canal walls in both groups was observed in the coronal third and the largest amount of the smear layer in the apical third. Conclusion. The most efficient cleaning of the canal was achieved by the use of citric acid and the intermittent protocol of the final irrigation. In all tested solutions, the intermittent protocol of irrigation was more efficient than continuous irrigation.

Introduction/Objective. The objective of this study is to use scanning electron microscopy (SEM) to analyze working surfaces of new manual and rotary endodontic instruments and to check possible existence of manufacture dirt particles or defects on the working surface. Methods. In this study, we used three sets of new manual instruments: K-File, KF (Dentsply Maillefer, Switzerland) and Hedstorm Files, HF (SybronEndo Co, USA) and three sets of mechanical Ni-Ti instruments – type K3 (SybronEndo Co, USA) and BioRaCe (FKG DENTAIRE Swiss Dental Products, Switzerland). The instruments were analyzed using SEM method at 170 × magnification while semi-quantitative energy dispersive x-ray analysis was used to determine chemical composition of dirt particles. Fisher test (p < 0.05) was applied in statistical analysis. Results. Results showed that none of the instruments were defect-free. The most common defect type was the presence of metal strips, which were noticed at the surface of all tested instruments. Debris was present on all manual and only one type of mechanical instruments, K3 (39% in the apical and 33% in the middle third). Fretting was noticed in all manual KF and all mechanical instruments of the K3 group. Pitting was common in all manual instruments, KF (33% in the apical and 39% in the middle third) and HF (11% in the apical and 6% in the middle third). Corrosion of the working surface, metal flash, and disruption of the cutting edge were marked only in the KF group. Conclusion. Manufacture defects were noticed in all instruments and the most common type of irregularity were metal strips. Electropolished surface of BioRaCe instruments showed no debris of organic origin.

Introduction/Objective. The application of nickel–titanium (NiTi) instruments in cleaning and shaping of the root canal system is a standard and a precondition for the success of endodontic treatment. The objective of this study was to use scanning electron microscopy (SEM) analysis in order to examine the efficiency of cleaning the apical third of the root canal system using two different NiTi systems with reciprocating movements. Methods. The study included 20 single-rooted teeth (premolars) divided into two groups. In group 1, the canal preparation was realized with a single file UNICONE with reciprocating movements (MEDIN, Inc., Nove Město na Moravě, Czech Republic), and in group 2, with а RECIPROC BLUE instrument with reciprocating movements (VDW GmbH, Munich, Germany). The same quantities of 2% NaOCl solution and 17% EDTA solution were used as irrigation solutions. The samples prepared for SEM analysis of the smear layer in the apical third were evaluated on a scale of 1–5 and at a magnification of 1,000×. Results. SEM analysis pointed to mostly clean canal walls in the apical segment in both tested groups. Slightly cleaner walls were observed after the application of the UNICONE file (78%) compared to the samples of the second group, where the instrumentation was realized by the RECIPROC BLUE file (76%), but without statistically significant differences. Conclusion. Single-file reciprocating systems do not remove the smear layer completely, but provide efficient cleaning of the apical region of the canal.

Cell wall content generally is regarded as the most important factor affecting forage utilization because it comprises the major fraction of forage dry matter and is correlated with forage intake and digestibility. The experiment was carried out to evaluate the cell wall constituents of ensiled pea - oat mixtures sown at five different seeding rates. Three effects were studied: application of bacterial inoculant, seeding rate of pea and oat in the mixtures and stages of plant development. The NDF (Neutral Detergent Fiber), ADF (Acid Detergent Fiber), hemicellulose, lignin and DMD (Dry Matter Digestibility) were determined in silages. Pea and oat were grown in binary mixtures at the experimental field of the Institute for forage crops, Kruševac - Serbia, and were tested at five different mixture rates: pure pea and pure oat crop, 25% pea + 75% oat, 50% pea + 50% oat, 75% pea + 25% oat. Application of bacterial inoculant affected lower content of NDF and hemicellulose (P< 0.05). Content of cell wall constituents decreased with increasing pea content in the mixtures, but DMD increased. On the other hand, content of cell wall constituents increased with plant growth and development, but DMD decreased.

Background/Aim. Non-melanoma skin cancers (NMSC) are ones of the most rapidly increasing cancers worldwide. Although NMSCs have a relatively low mortality rate, they are an important public health concern and the most costly cancers in many countries. The two main objectives in this study were: first, to analyze the trend of age-standardized incidence rate of NMSCs in Serbia and second, to assess the need for national prevention and control strategy based on analyzed trend. Methods. From the Serbian Cancer Registry, we extracted all cases of NMSCs registered in central Serbia from January 1, 1999 to December 31, 2015. Joinpoint regression analysis was used to define trends and annual percentage change (APC). Results. NMSCs significantly increased for both genders with APC of +2.32% (p < 0.001). Significantly increasing trend of incidence rates was higher in women (APC, +2.63%; p < 0.0001) than in men (APC, +2.01%; p < 0.001). Conclusion. Our results show a continuously increasing incidence rate of NMCS in Serbia. Without the national preventive strategy, current sporadic activities are highly unlikely to result in reducing the growing trends

The flow field phenomena that occur as a result of thrust vector control (TVC) system activity on a missile with lateral jets are very complex and influence all other components of the missile. Influence is more significant when TVC is generating commands, when jets are asymmetrically directed. The main goal of these study was to determine the influence of of the hot rocket motor's combustion products on the basis of the CFD model proven with the cold-jet simulation. Based on obtained experimental aerodynamic coefficients for the cold-jet simulation the preliminary aerodynamic CFD model was designed. Three-dimensional Reynolds averaged Navier-Stokes numerical aerodynamic and hot-jet simulations were carried out to predict the aerodynamic loads of the missile based on the finite volume method. The study resulted in the definition of a methodology for the investigation of the jet reaction effects in a wind tunnel. A method for determining of the TVC system interference on the aerodynamic characteristics, as a basic prerequisite for structural, stability and performance analysis, was proposed. Mutual verification and validation process was carried out through experiment and proper application of the commercial CFD software code for calculation aerodynamic effects of the hot gases lateral jets on the performance of a guided missile. Experimental and computational results of the pitching moment coefficients are presented and agreed well with.