Calibration of the rutting model in HDM 4 on the highway network in Macedonia

The World Bank HDM 4 model is adopted in many countries worldwide. It is consisted of the developed models for almost all types of deformation on the pavement structures, but it can’t be used as it is developed everywhere in the world without proper adjustments to local conditions such as traffic load, climate, construction specificities, maintenance level etc. This paper presents the results of the researches carried out in Macedonia for determining calibration coefficient of the rutting model in HDM 4

Calibration of the rutting model in HDM 4 on the highway network in Macedonia

The World Bank HDM 4 model is adopted in many countries worldwide. It is consisted of the developed models for almost all types of deformation on the pavement structures, but it can’t be used as it is developed everywhere in the world without proper adjustments to local conditions such as traffic load, climate, construction specificities, maintenance level etc. This paper presents the results of the researches carried out in Macedonia for determining calibration coefficient of the rutting model in HDM 4

Calibration of the rutting model in HDM 4 on the highway network in Macedonia

The World Bank HDM 4 model is adopted in many countries worldwide. It is consisted of the developed models for almost all types of deformation on the pavement structures, but it can’t be used as it is developed everywhere in the world without proper adjustments to local conditions such as traffic load, climate, construction specificities, maintenance level etc. This paper presents the results of the researches carried out in Macedonia for determining calibration coefficient of the rutting model in HDM 4

Long term studies on the impact of thionic bacteria on the global pollution of waters with toxic ions

The biogeochemical activity of microorganisms from sulphide biogeocoenosis in the zones of sulphide copper ores deposits in East Serbia has been Studied by us since 1975. All deposits of copper mineralization were dominantly sulphides and arsenic sulphides with the constant presence of pyrite. The obtained results proved that the biochemical and chemical activity of thionic bacteria have an influence on the global pollution of waters. All the waters were characterized by a low pH value and by high Eh values, mineralization (over 7 gL(-1)) and in total iron (even more than 4 gL(-1)) dominantly as Fe3+ ions. These waters were characterized by toxic concentrations of copper ions, within the limits from about 2 to almost 200 mgL(-1) and arsenic, up to more than 4 mgL(-1). These waters partly arrive in an aquifer and the major part flows into surface water courses gravitating towards the Danube River, which empties into the Black Sea. In a hypothetical case, if maximum concentrations of copper and arsenic and maximum capacity of the springs are considered, under the assumption that the pollutants do not precipitate on the way to the main recipient, the striking information is obtained that the Danube River receives about 31 t of copper and more than 0.6 t of arsenic per annum from one place alone, which undoubtedly points to the contribution of thionic bacteria as "biological agents" to global pollution of surface and ground waters.BIOHYDROMETALLURGY: A MEETING POINT BETWEEN MICROBIAL ECOLOGY, METAL RECOVERY PROCESSES AND ENVIRON

Cone-Beam Computed Tomography Study of the Root Canal Morphology of Mandibular Anterior Teeth in Serbian Population

The aim of this study is to describe the morphological characteristics, the number of roots and number of root canals of mandibular central incisors, lateral incisors and canines, and the relationship of these characteristics with the sex and the jaw side where the tooth is located, in the Serbian population using cone-beam computed tomography (CBCT)

Cone-beam computed tomography study of the root canal morphology of mandibular anterior teeth in Serbian population

© 2018, University of Kragujevac, Faculty of Science. All rights reserved. The aim of this study is to describe the morphological characteristics, the number of roots and number of root canals of mandibular central incisors, lateral incisors and canines, and the relationship of these characteristics with the sex and the jaw side where the tooth is located, in the Serbian population using cone-beam computed tomography (CBCT). CBCT images of a total of 902 mandible front teeth, including 296 central incisors, 294 lateral incisors and 312 canines were analyzed in the database. For assessing the morphology of the root canal, Vertucci method of classification was used. Central incisors had two canals in 27%, similar as lateral incisor which had two canals in 26.5%. Mandibular canines had two canals in 7.1% and there was a significant difference between genders. The most prevalent root canal configuration type in all mandibular anterior teeth was type I. In the groups of mandibular incisors with two root canals the most common was type III. In the group of mandibular canines with two root canals, type V had the greatest occurrence. Most mandibular anterior teeth had one root canal. Two root canals were found in 27% of the mandibular incisors. There is a significant difference in root morphology between genders. It is important for dental practitioner to expect different morphological variations when performing endodontic treatment. More studies are needed to further define morphological characteristics of roots of mandibular anterior teeth in Serbian population

The Evaluation of Healing Properties of <i>Galium verum</i>-Based Oral Gel in Aphthous Stomatitis in Rats

Although oral ulcers represent one of the most frequent oral mucosal diseases, the available treatment is not sufficient to provide complete ulcer recovery without side-effects. Therefore, the aim of our study was to prepare a mucoadhesive oral gel based on Galium verum ethanol extract (GVL gel) and reveal its healing effects in the model of aphthous stomatitis in rats. Rats with oral ulcers were divided into the following groups: control (untreated), gel base (ulcer was treated with the gel base, three times per day for 10 days), and GVL gel group (the ulcer was treated with GVL gel in the same way as the gel base). Animals from each group were sacrificed on days 0, 3, 6, and 10 for collecting blood and ulcer tissue samples. Healing properties of oral gel were determined by clinical evaluation, as well as biochemical and histopathological examinations. Our findings suggest a significant decrease in the ulcer size in GVL gel group, with healing effects achieved through the alleviation of oxidative stress, reduction in COX-2 immunopositivity, and increase in collagen content in buccal tissue. Significant ulcer repairing potential of GVL gel highlights this oral mucoadhesive gel as a promising tool for prevention and treatment of RAS

Enhanced in situ bioremediation of groundwater contaminated by petroleum hydrocarbons at the location of the Nitex textiles, Serbia

This study provides insight into the enhanced in situ bioremediation applied for remediation of groundwater contaminated by petroleum hydrocarbons. Activities prior to the application of this remediation approach included removal of the source of groundwater contamination-an underground storage tank and contaminated sediments-from the unsaturated zone. The hydraulic feasibility of this remediation approach was proved by hydraulic conductivity characterization of the site. Enhanced in situ bioremediation was performed by a combination of biostimulation and bioaugmentation within the closed bipolar system (one extraction and two injection wells). Biostimulation was conducted by addition of nutrients, and stimulation of oxidation processes by injection of H2O2, into the aquifer. Bioaugmentation/re-inoculation was achieved by injection of a zymogenous consortium of hydrocarbon degrading microorganisms isolated from the contaminated groundwater. The average extraction capacity was 0.5 l/s, with an average injection capacity of 0.25 l/s per well. The efficiency of the remediation approach was measured by changes in the content of total petroleum hydrocarbon (TPH), total chemoorganoheterotrophic (TC) and hydrocarbon degrading (HD) microorganisms. After biostimulation and bioaugmentation, the number of TC and HD microorganisms started to increase. This was followed by a decrease of TPH concentration in the groundwater from an initial 6.8-0.5 mg/l at the end of the bioremediation. The applied remediation approach was highly efficient and very effective in reducing TPH to acceptable levels. Together, these facts provide strong evidence of its potential for remediation of groundwater contaminated by petroleum hydrocarbons

Biodegradation of Isoprenoids, Steranes, Terpanes, and Phenanthrenes During In Situ Bioremediation of Petroleum-Contaminated Groundwater

The objective of this study was to stimulate microbial biodegradation of petroleum pollution in groundwater and to analyze changes in the abundance and distribution of organic compounds detectable in petroleum. Bioremediation was conducted in a closed bipolar system, by bioaugmentation with consortia of hydrocarbon degrading microorganisms (HD) and biostimulation with nutrients. Comprehensive twodimensional gas chromatography-mass spectrometry (GC X GC-MS) was used to visualize all fractions simultaneously. During the study, the content of total petroleum hydrocarbon (TPH) in groundwater decreased by 92.7% of the initial level, and the average rate of biodegradation was 0.1 mg/L per day. Increased numbers of HD were observed and the dominant genera were Pseudomonas, Rhodococcus, Achromobacter, Bacillus, and Micromonospora. In the first 30 days of bioremediation, there was no significant biodegradation of n-alkanes and petroleum biomarkers - isoprenoids such as pristane and phytane, and polycyclic-saturated hydrocarbons such as terpanes and steranes. However, after 60 days of bioremediation, more than 95% of n-alkanes, terpanes and steranes were biodegraded. Phenanthrene and its methyl-,dimethyl-, and trimethyl-isomers were biodegraded and reduced by more than 99% of their initial levels. However, their decomposition had clearly commenced after just 30 days. This is a somewhat surprising result since it follows that the phenanthrenes were more susceptible to biodegradation than the n-alkanes and isoprenoids. Depending on the microbial community used for bioaugmentation, biodegradation of phenanthrene can precede biodegradation of saturated hydrocarbons.Peer-reviewed version: [http://cer.ihtm.bg.ac.rs/handle/123456789/2925

Natural attenuation of petroleum hydrocarbons-a study of biodegradation effects in groundwater (Vitanovac, Serbia)

The role of natural attenuation processes in groundwater contamination by petroleum hydrocarbons is of intense scientific and practical interest. This study provides insight into the biodegradation effects in groundwater at a site contaminated by kerosene (jet fuel) in 1993 (Vitanovac, Serbia). Total petroleum hydrocarbons (TPH), hydrochemical indicators (O-2 , NO3-, Mn, Fe, SO42-, HCO3- ), delta C-13 of dissolved inorganic carbon (DIC), and other parameters were measured to demonstrate biodegradation effects in groundwater at the contaminated site. Due to different biodegradation mechanisms, the zone of the lowest concentrations of electron acceptors and the zone of the highest concentrations of metabolic products of biodegradation overlap. Based on the analysis of redox-sensitive compounds in groundwater samples, redox processes ranged from strictly anoxic (methanogenesis) to oxic (oxygen reduction) within a short distance. The dependence of groundwater redox conditions on the distance from the source of contamination was observed. delta C-13 values of DIC ranged from -15.83 to -2.75 parts per thousand, and the most positive values correspond to the zone under anaerobic and methanogenic conditions. Overall, results obtained provide clear evidence on the effects of natural attenuation processes-the activity of biodegradation mechanisms in field conditions