Vol. 10 No. 1 Ā· 2020
We propose an alternative approach to Boltzmann distribution concerning the hydrogen atom and compare our results to previous formalism for some observables.
Stark full widths at half maximum (FWHM) for 26 6s-6p transitions in Tb III spectrum have been calculated for electron density of 1017 cm-3 within a temperature range of 5 000 K to 80 000 K, by using the simplified modified semiempirical (SMSE) method. The results obtained are used for the consideration of Strak width regularities within the investigated transition array.
Recent climate changes cause significant natural and socio-economic consequences. They represent one of the major environmental problems of the late 20th and early 21st centuries. Changes in temperature and precipitation play a significant role in understanding climate change issues. They include numerous extreme climatic events such as heat waves, droughts, forest fires and more. Looking at regional differences in temperature and precipitation regime change, Southern Europe, including the Republic of Serbia, occupies a special place. The MaÄva district (3.272 kmĀ²) is almost four times as spacious as the MaÄva area. The administrative-political division of the MaÄva district is comprised of eight municipalities. The paper presents trends of two climate variables: mean annual air temperature and mean annual precipitation in the study area. In methodological sense, the main statistical procedure is the non-parametric Mann-Kendall (MK) test. Data from three available meteorological stations in the MaÄva district (1949-2015) were used for the analysis. The presented results of the trends in air temperature indicate that there is a statistically significant positive trend in all-time series. In trends, precipitation amounts a statistically significant positive trend was observed in two time series, while in one there is no trend. The expressed trends, especially in the case of air temperatures, lead to the possibility of drought. MaÄva district and MaÄva have some agricultural importance in the Republic of Serbia. For these reasons, some adaptation to climate change is needed as arid conditions lead to fluctuations in agricultural yield.
It is widely known that some surfaces contain special curves as a geodesics, while a lots of geodesics on surface have complicated shapes. Goal of this research is to find on what surfaces are u- and v- parameter curves geodesics. Developable surfaces that contain a given plane curve as a geodesic are studied in the article, whereas the plane curve is also an initial u-parameter curve on that surface. Parametric equations of the minimal surfaces that contain an epicycloid as a geodesic are also given. Visualization of geodesics was done in Mathematica.
This paper presents the results of the analyzed trends for three categories of parameters: average annual air temperature (YT), average maximum air temperature (YTx) and average minimum air temperature (YTn) for the Podgorica Meteorological Station in the Republic of Montenegro. The aim of this paper is to present possible climate changes based on the results obtained from the analyzed air temperature trends. The methodology is based on the application of: a) linear trend equations, b) trend magnitudes and c) Mann-Kendall trend test. The data from the respectable meteorological station in Podgorica for the period from 1947 to 2018 were used in order to estimate the trend. The obtained results indicate a statistically significant positive trend for all analyzed time series. Analyzing the trend test hypotheses, it was concluded that in all three cases the Ha hypothesis prevails. Average annual air temperature in Podgorica increased by 1.4Ā°C, average maximum air temperature increased by 2.5Ā°C and average minimum air temperature increased by 0.6Ā°C. In accordance with the trends analyzed, the increase in air temperature is dominant in the capital of the Republic of Montenegro.
Considering the facts that phenolic compounds have many pharmacological effects, as well that antioxidant effect of phenolic compounds has been proven in various experimental systems, aim of this research was to determine the content of total phenols and flavonoids and evaluation of antioxidant activity in ethanol, ethyl acetate and chloroform extracts of fruits and leaves of the plant species Crataegus monogya Jacq., which is known as common hawthorn. The content of total phenolic compounds was determined by the spectrophotometric method using Folin-Ciocalteu reagent and the content of flavonoids was determined using aluminum chloride. In vitro evaluation of the antioxidant activity of tested extracts was performed using the DPPH method. The amount of total phenolics was varied in fruits and leaves extracts and ranged from 38.05 Ā± 0.18 to 365.11 Ā± 0.32 mg GAE/g dw. Ethyl acetate extract of hawthorn leaves showed the highest content of phenolic compounds (365.11 Ā± 0.32 mg GAE/g dw). The flavonoid content was different in the fruits and leaves of hawthorn and ranged from 21.11 Ā± 0.11 to 122.98 Ā± 0.21 mg RU/g dw, whereby the highest content of flavonoids was found in ethyl acetate extract of leaves (122.98 Ā± 0.21 mg RU/g dw). Antioxidant activity of the tested extracts was expressed as IC50 values and ranged from 5.53 Ā± 0.08 to 293.51 Ā± 0.28 Ī¼g/ml. Ethyl acetate extract of hawthorn leaves showed considerable antioxidant potential (IC50 = 5.53 Ā± 0.08 Ī¼g/ml). Based on the obtained results, a significant correlation was found between the antioxidant activity and the content of total phenolics and flavonoids compounds in hawthorn fruits and leaves extracts.
Polynuclear silver(I) complex, [Ag(NO3-O)(2,2ā-bq-N,Nā)]n, was synthesized by the reaction of equimolar amount of silver(I) nitrate and 2,2ā-biquinoline (2,2ā-bq) in ethanol at room temperature. The characterization of the complex was established on the basis of elemental microanalysis, IR, NMR (1H and 13C) and UV-Vis spectroscopic techniques. The results of spectroscopic analyses revealed that in [Ag(NO3-O)(2,2ā-bq-N,Nā)]n complex, 2,2ā-bq ligand behaves as a chelate, while the remaining coordination sites are occupied by the oxygen atoms of two nitrates.
Smart cities are driven by huge amount of data collected from sensors deployed across the city. Sensors typically form a multi-hop network with a base station (BS) in order to send their data to the command and control center. However, sparse deployment of sensors can leave subsets of the network partitioned from the rest of the network. In such a case, isolated partitions cannot forward their data to the BS. Consequently, network coverage and data fidelity decline. A possible solution to link partitions and provide connectivity is employing mobile data collectors (MDCs). A smart vehicle supporting wireless communication can act as an MDC and carry data between sensors and the BS. Using a single MDC extends the average tour length. To minimize the maximum tour length, multiple MDCs can be employed. To identify sensors to be visited by each MDC, this paper clusters partitions as many as the number of MDCs and assigns an MDC for each cluster. Then two different cooperative data collection schemes are considered based on the availability of inter-MDC data exchange. If MDCs collaborate in data delivery, they meet at certain meeting points for data exchange. Such a cooperation avoids the requirement of visiting the BS for some MDCs and reduces tour lengths. On the other hand, MDCs closer to the BS can experience data loss due to buffer overflow given the higher volume of the accumulated data. Presented approaches are evaluated in terms of maximum tour length, data latency, and data loss. The smart city application is simulated with deployment of sensors on certain amenity types. Geographic data is obtained from a volunteered geographic information system and MDC mobility is restricted with the road network. Obtained results indicate that MDC cooperation decreases maximum tour length at the expense of increased rate of data loss and data latency.
Different modified Newtonās methods are widely used in modern computational engineering science, applied mechanics, economics, optimization problems and other disciplines. On the other hand aggregation of information takes a significant place in many knowledge-based systems, where aggregation of data or values is needed. In this paper we theoretically analysed a new modification of Newtonās method based on aggregation function applied on finding multiple roots of nonlinear equations, and numerically verified theoretical results on the examples with simple and multiple roots. Numerical analysis of the proposed approach with obtained results and the related discussion are presented on examples in practice.
This paper shows the presence of the rural geometer moths in 15 localities of Kosovo and Metohia (Serbia). A review of existing data regarding the area of Kosovo and Metohia is given. Through research, the presence of 48 species was revealed. Between them, five species are reported as new for the fauna of Kosovo and Metohia: Plagodis pulveraria (Linnaeus, 1758), Scotopteryx luridata (Hufnagel, 1767), Catarhoe cuculata (Hufnagel, 1767), Anticlea badiata (Denis & SchiffermĆ¼ller, 1775) and Anticlea derivata (Denis & SchiffermĆ¼ller, 1775).
This study examined early stages (3-5 years) of spontaneous primary vegetation succession on a model locality drastically altered by long term fluvial deposition of copper tailings in Eastern Serbia. In a large-scale survey, 115 samples of herbaceous vegetation (with a total of 75 species) were harvested from standardized 1m x 1m quadrates, and concomitant soil samples collected and their relevant physicochemical properties analysed. Primary succession depended on the establishment of five pioneer species (Rumex acetosella, Agrostis capillaris, Calamagrostis epigeios, Persicaria lapathifolia and Chenopodium botrys). Unconstrained ordination showed very clear vegetation gradients, significantly correlated with the key soil constraints (from Cu excess to low pH and nutrient deficiency), while the distribution of the five edificatory pioneers showed high degree of dependence on the micro-level habitat conditions. This work demonstrates that in such a complex setup with severe abiotic filtering, sufficient sampling effort can reveal strong patterns in a process commonly considered very stochastic.
Due to their diverse metabolic potential, many filamentous fungi have a great ability for degradation of different waste substances. The present research was aimed to investigate ability of fungi Mucor plumbeus, Aspergillus niger and Trichoderma harzianum, isolated from sewer and industrial waste water, to conduct degradation of high concentrations of commercial detergent (0.3%). Within enzyme extracts of samples taken during period of 3ā16 days, activity of alkaline invertase and alkaline phosphatase was followe spectrophotometrically at room temperature. Obtained results proved that all examined fungi affected degradation of detergent. Quality (inhibition/stimulation) and quantity of action of detergent on activity of investigated enzymes depended on fungal species and incubation period. The highest inhibiting effect of detergent was recorded on 9th day of incubation in samples of T. harzianum and A. niger, while its most obvious stimulating effect was noticed on 3rd day of incubation in samples of T. harzianum and M. plumbeus. Investigated fungi can be used for purification of waste water containing high concentrations of detergent.