Neural network modeling of dissolved oxygen in the Gru?a reservoir, Serbia

The objective of this study is to develop a feedforward neural network (FNN) model to predict the dissolved oxygen in the Gru?a Reservoir, Serbia. The neural network model was developed using experimental data which are collected during a three years. The input variables of the neural network are: water pH, water temperature, chloride, total phosphate, nitrites, nitrates, ammonia, iron, manganese and electrical conductivity. Sensitivity analysis is used to determine the influence of input variables on the dependent variable. The most effective inputs are determined as pH and temperature, while nitrates, chloride and total phosphate are found to be least effective parameters. The Levenberg-Marquardt algorithm is used to train the FNN. The optimal FNN architecture was determined. The FNN architecture having 15 hidden neurons gives the best choice. Results of FNN models have been compared with the measured data on the basis of correlation coefficient (r), mean absolute error (MAE) and mean square error (MSE). Comparing the modelled values by FNN with the experimental data indicates that neural network model provides accurate results.     

Workspace design for crane cabins applying a combined traditional approach and the Taguchi method for design of experiments

Procedures in the development process of crane cabins are arbitrary and subjective. Since approximately 42% of incidents in the construction industry are linked to them, there is a need to collect fresh anthropometric data and provide additional recommendations for design. In this paper, dimensioning of the crane cabin interior space was carried out using a sample of 64 crane operators’ anthropometric measurements, in the Republic of Serbia, by measuring workspace with 10 parameters using nine measured anthropometric data from each crane operator. This paper applies experiments run via full factorial designs using a combined traditional and Taguchi approach. The experiments indicated which design parameters are influenced by which anthropometric measurements and to what degree. The results are expected to be of use for crane cabin designers and should assist them to design a cabin that may lead to less strenuous sitting postures and fatigue for operators, thus improving safety and accident prevention.     

Biotreatment strategies for the removal of microplastics from freshwater systems. A review

Environmental Chemistry Letters - Research on plastic pollution has recently evidenced the ubiquitous presence of tiny plastic particles called microplastics. Microplastics alter organisms because...     

Time profile of abamectin and doramectin excretion and degradation in sheep faeces

We studied abamectin and doramectin excretion and their degradation in sheep faeces under field conditions on pasture after a single subcutaneous dose (0.2mg/kg body weight). In the excretion experiment, maximal abamectin concentration (1277 ng/g dry faeces) was detected on day 3, while doramectin concentration showed two peaks (2186 and 1780 ng/g dry faeces on days 2 and 5, respectively). Both avermectins were excreted at approximately the same rate (k=0.23 day(-1) for abamectin and 0.19 day(-1) for doramectin). In the field, a rapid loss of abamectin and doramectin from sheep faeces was seen during the first 32 days after which concentrations remained constant at approximately 77 ng/g and 300 ng/g, respectively. The half life values (DT(50)) for abamectin and doramectin dissipation from sheep faeces were 23 and 22 days, respectively, during the first 32 days. Dissipation of both avermectins was strongly correlated with moisture content of the faeces.     

Radon concentrations in a spa in Serbia

The paper presents the results of indoor radon concentration survey in 201 homes and offices in Niska Banja (the Spa of Nis), a well-known health resort and a spa in the South-East of Serbia. Radon indoor concentrations were determined by active charcoal method, according to standard EPA procedure. The indoor radon concentrations were in the range of up to 200 Bq/m(3) (47%), from 200-600 Bq/m(3) (26%) and over 600 Bq/m(3) (27%). Three areas of extremely high average radon concentrations were found (1,340-4,340 Bq/m(3)), with a maximum above 13,000 Bq/m(3). The content of natural radionuclides ((226)Ra, (214)Pb, (214)Bi, (235)U, (228)Ac, (212)Pb, (212)Bi, (208)Tl, (40)K) and (137)Cs, as well as the content of total uranium, thorium and potassium in mud used in peloidotherapy in the Health Institute "Niska Banja" was determined, too. The activities of the radionuclides were determined on an HPGe detector, by standard gamma spectroscopy. The results indicated considerably high amounts of total uranium and thorium (0.021 g/kg mud and 0.003 g/kg mud, respectively), due to the karsts origin of the soil.     

Cadmium effects on the fitness-related traits and antioxidative defense of Lymantria dispar L. larvae

Cadmium, like many other pollutants, is nondegradable and can be accumulated by Lymantria dispar at a level that affects fitness components, physiology, and development, which could indicate presence of environment pollution by heavy metals. The cadmium effect on fitness-related traits in the third, fourth, fifth, and sixth instar of L. dispar L. was determined. Furthermore, activities of the following antioxidative defense components after the larvae had been fed on the artificial cadmium-supplemented diet (50 μg Cd/g dry food) were assessed: superoxide dismutase (SOD), catalase (CAT), ascorbate peroxidase (APOX), total glutathione amount (GSH), glutathione-S-transferase (GST), glutathione reductase (GR), and the amount of free sulfhydryl (SH) groups. Statistically significant delay of development in the fourth, fifth, and sixth instar and decrease of the larval mass in the third and fourth instar were estimated after the exposure to cadmium through food in comparison to the control. There were no changes in SOD activity of cadmium-treated larvae. Significantly lower CAT, APOX, and GR activities were recorded in the third, fifth, and in the third instar, respectively. At the same time, higher activity was recorded in the sixth instar, while GST activity was higher in the third. GSH content was significantly lower during all instars after treatment but the amount of SH groups was higher in older larvae. The strategy of antioxidative defense and the adjustment or modulation of fitness-related traits in presence of cadmium was dependent on the age of larvae in L. dispar, which might be used in early metal risk assessment in Lepidoptera and other insects.     

Enzymatic biomarkers as indicators of dietary cadmium in gypsy moth caterpillars

Heavy metals damage the structure, chemistry, and function of cells, including enzyme systems inside them. Variation in the profile of biochemical biomarkers in prevalent species should be used for assessing environmental contamination. The present study pays attention to the phosphatases present in the midgut of gypsy moth fourth instar caterpillars, which had been exposed to short- and long-term cadmium intake at 10 and 30 μg Cd/g dry food. Chronic cadmium ingestion significantly inhibited the activity of all examined phosphatases, while only the activity of lysosomal phosphatase was acutely decreased. Total acid phosphatase activity recovered from both long-term cadmium treatments within 3 days. The low index of phenotypic plasticity was connected to high variability of plasticity. Dependence of phosphatase isoforms on genotype and duration of cadmium treatment was determined. We concluded that, with further investigations, profiling of total acid phosphatase activity, as well as the lysosomal fraction can be used as a biomarker for acute sublethal metal toxicity.     

Establishment of control site baseline data for erosion studies using radionuclides: a case study in East Slovenia

The aim of the present study was to establish a reference site and its soil characteristics for use of fallout radionuclides in erosion studies in Slovenia. Prior to this study, no reference site and baseline data existed for Slovenia for this purpose. In the agricultural area of Gori?ko in East Slovenia, an undisturbed forest situated in Šalamenci (46°44’N, 16°7’E), was selected to establish the inventory value of fallout ¹³⁷Cs and to establish a baseline level of multi-elemental fingerprint (major, minor, trace elements including heavy metals) and naturally occurring radionuclides in soils. A total of 20 soil profiles were collected at four 10 cm depth increments for evaluation of baseline level of ¹³⁷Cs inventory. An exponential distribution for ¹³⁷Cs was found and the baseline level inventory was established at 7300 ± 2500 Bq m⁻² with a coefficient of variation of 34%. Of this mean present-day inventory, approximately 45% is due to the Chernobyl contribution.The physical degradation of soils through erosion is linked with biochemical degradation. This study introduces an approach to establishment of the naturally occurring radionuclide and elemental fingerprints baseline levels at a reference site which can provide comparative data to those from neighbouring agricultural fields for assessment of soil redistribution magnitude using fallout radionuclides. In addition, this information will be used to determine the impact of soil erosion processes and agricultural practices on soil quality and redistribution within agricultural landscapes in Slovenia.