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Two significant phenomena that have occurred in the past few years have been emigration and the COVID-19 pandemic crisis. These events shook the world on a global level, causing political, economic, social and other consequences. These two crises seem to have been used to achieve certain political goals, both nationally and globally. Thus, political goals came to the fore in the defense against the crisis. However, the crisis of the pandemic is more relevant by nature, because it is about people's lives and health, globally, encompassing all countries, different nations, cultures, religions, but also different gender, age, education and other structures. The crisis of the pandemic and the fight against it is aggravated by migration, environmental, economic and other crises, which means that these are integrated crises to which an integrated or holistic response should be given. Medical and pharmaceutical science and the profession found themselves in a delicate situation, to respond to the challenges of mass infection with the C-19 virus, and both were not prepared to respond to the pandemic, and this disorientation caused "cracks" that led to undermined public confidence in medicine and the subordination of the medical profession to politics. This is more or less a statement that applies to the whole world, and especially to transition countries with a low level of democracy and without strong health, but also other institutions. The paper deals with the place and role of medical science and profession in the COVID-19 pandemic and the problems that led to the ideologisation, but also the commercialization of the pandemic. The aim of the paper is to point out certain problems in the management of the pandemic, so that they would not appear in the next mass crises

This paper presents theoretical considerations and working parameters analyzes of hydrotransport during unstable flow. The variable flow of hydraulic mixture in installations causes unsteady operation and pipes spraying, pump damage, obturation in various sections of the pipeline, reduced capacity as well as higher operating costs. Using mathematical equations presented in this paper, such parameters of the hydraulic mixture, hydrotransport installation and control devices can be determined which protect system from possible clogging. Considering the fact that critical speed of hydraulic mixture depends on transported material grain size, mixture volume mass, diameter of pipeline and specific gravity of solid phase, it is possible to accurately analyze obturation in hydrotransport installations depending on those parameters. In order to prevent hydraulic impacts in hydrotransport installation pipelines, which value can be determined mathematically, it is necessary to adjust installation to hydromixture parameters and pump, or vice versa.

The aim of this study was: I) to determine Pb, Cd and Zn concentrations in alluvial soil before and after planting selected plant species, and II) modeling of the bioaccumulation process in the examined soil, using several plant species. Soil samples were collected from the northern part of Kosovo and Metohija, and the selected plants were: a) vegetables: Lactuca sativa L. and Allium cepa L.; b) legumes: Lotus corniculatus L. and Trifolium pratense L.; and c) grasses (weed plants): Cynodon dactylon (L.) Pers. and Festuca arundinaceae Schreb. The experimental part of the work was carried out by vegetation experiments, and heavy metal concentrations were determined by potentiometric stripping analysis (PSA). The obtained results show that: I) the heavy metal concentrations in the analyzed soil were above allowed values at all measuring points; II) the selected species accumulated heavy metals to some extent. Expressed in percentages, vegetables and legumes accumulated 9−11 % Pb, 12−33 % Cd and 11−19 % Zn. Cyndon dactylon Pers. accumulated about 69 % Pb, 24−40 % Cd and 43 % Zn. Festuca arundinaceae accumulated 39−40 % Zn, 58−81 % Cd, and Pb up to 70 %. The obtained results indicate high tolerance to heavy metals, especially in the case of Festuca arundinacea. By simulation of the bioaccumulation process it has been established that the dependence of the concentration of metal ions before and after planting represents a linear regression. Coefficients of the model, for the discussed cases of heavy metals and plant species, were determined by minimization of the mean square error, and quality of model fits was evaluated by the values of the statistical indicators the RSE (Residual Standard Error) and MRE (Mean Relative Error). The closer the values of these indicators are to zero, the more accurate the model is. It can be concluded that the adopted model describes sufficiently well the dependence of concentrations of Pb and Zn in the soil before and after planting. The mean relative error (MRE) in the case of Cd is slightly higher than 7 %, which suggests that the use of a non-linear model is needed for which it is necessary to have additional samples available, which can be the subject of further research.

This paper presents kinetics modeling of essential oil hydrodistillation from juniper berries (Juniperus communis L.) by using a non-linear regression methodology. The proposed model has the polynomial-logarithmic form. The initial equation of the proposed non-linear model is q = q∞•(a•(logt)2 + b•logt + c) and by substituting a1=q∞•a, b1 = q∞•b and c1 = q∞•c, the final equation is obtained as q = a1•(logt)2 + b1•logt + c1. In this equation q is the quantity of the obtained oil at time t, while a1, b1 and c1 are parameters to be determined for each sample. From the final equation it can be seen that the key parameter q∞, which presents the maximal oil quantity obtained after infinite time, is already included in parameters a1, b1 and c1. In this way, experimental determination of this parameter is avoided. Using the proposed model with parameters obtained by regression, the values of oil hydrodistillation in time are calculated for each sample and compared to the experimental values. In addition, two kinetic models previously proposed in literature were applied to the same experimental results. The developed model provided better agreements with the experimental values than the two, generally accepted kinetic models of this process. The average values of error measures (RSS, RSE, AIC and MRPD) obtained for our model (0.005; 0.017; –84.33; 1.65) were generally lower than the corresponding values of the other two models (0.025; 0.041; –53.20; 3.89) and (0.0035; 0.015; –86.83; 1.59). Also, parameter estimation for the proposed model was significantly simpler (maximum 2 iterations per sample) using the non-linear regression than that for the existing models (maximum 9 iterations per sample). [Project of the Serbian Ministry of Education, Science and Technological Development, Grant no. TR-35026]

The present work deals with modeling the kinetics of essential oils extraction from plant materials by water and steam distillation. The experimental data were obtained by studying the hydrodistillation kinetics of essential oil from juniper berries. The literature data on the kinetics of essential oils hydrodistillation from different plant materials were also included into the modeling. A physical model based on simultaneous washing and diffusion of essential oil from plant materials were developed to describe the kinetics of essential oils hydrodistillation, and two other simpler models were derived from this physical model assuming either instantaneous washing followed by diffusion or diffusion with no washing (i.e. the first-order kinetics). The main goal was to compare these models and suggest the optimum ones for water and steam distillation and for different plant materials. All three models described well the experimental kinetic data on water distillation irrespective of the type of distillation equipment and its scale, the type of plant materials and the operational conditions. The most applicable one is the model involving simultaneous washing and diffusion of the essential oil. However, this model was generally inapplicable for steam distillation of essential oils, except for juniper berries. For this hydrodistillation technique, the pseudo first-order model was shown to be the best one. In a few cases, a variation of the essential oil yield with time was observed to be sigmoidal and was modeled by the Boltzmann sigmoid function.

Copyright of Estonian Journal of Earth Sciences is the property of Teaduste Akadeemia Kirjastus and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Analogue (and addressable) fire detection systems enables a new quality in improving sensitivity to real fires and reducing susceptibility to nuisance alarm sources. Different decision algorithms types were developed with intention to improve sensitivity and reduce false alarm occurrence. At the beginning, it was free alarm level adjustment based on preset level. Majority of multi-criteria decision work was based on multi-sensor (multi-signature) decision algorithms - using different type of sensors on the same location or, rather, using different aspects (level and rise) of one sensor measured value. Our idea is to improve sensitivity and reduce false alarm occurrence by forming groups of sensors that work in similar conditions (same world side in the building, same or similar technology or working time). Original multi-criteria decision algorithms based on level, rise and difference of level and rise from group average are discussed in this paper.

One of the basic equations of mathematical physics (for instance function of two independent variables) is the differential equation with partial derivatives of the second order (3). This equation is called the wave equation, and is provided when considering the process of transverse oscillations of wire, longitudinal oscillations of rod, electrical oscillations in a conductor, torsional vibration at waves, etc… The paper shows how to form the equation (3) which is the equation of motion of each point of wire with abscissa x in time t during its oscillation. It is also shown how to determine the equation (3) in the task of electrical oscillations in a conductor. Then equation (3) is determined, and this solution satisfies the boundary and initial conditions.

The main problem of hydraulic transport is the resistance generated during the mixture transport through the pipe-line. Testing the flow characteristics of mixtures, shown in this paper, are based on the principles of determining the unit energy losses by a mathematical calculation using the non-linear regression - the Levenberg-Marquardt algorithm. Such obtained results allow determining a transport rate in the horizontal pipe-line, depending on the mixture bulk density and pipe-line diameter. The flotation tailings is mainly used as a filling material in the mine "Trepca" - Stari Trg. According to the grain size distribution, it is a finegrained material of a size of 0.074 mm to 1.2 mm. It is a multicomponent material containing pyrite, pyrrhotine and other heavy metals, and therefore, has a high bulk mass. The average rate of the hydromixture, in which the energy losses reach the minimum value, depends on the pipe-line diameter and kinetic bulk density of the mixture. For the test interval of change in the pipe-line diameter, shown in this paper (0.168 mm, 0.176 mm, 0.193 mm, and 0.225 mm), and kinetic bulk density of the hydraulic mixture (1-1.6 kg/m³), this rate ranges from 3-5.5 m/s. The increase of the energy losses in the hydraulic mixture transport increases proportionality with the increase of its kinetic bulk density. The results, presented in this paper, show that the required bulk density of 1.6 kg/m³ should be accepted as a limit from a point of view of the hydraulic transport cost-efficiency. [ABSTRACT FROM AUTHOR]

Copyright of Facta Universitatis: Series Physical Education & Sport is the property of Facta Universitatis, Series Physical Education & Sport and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

One of the basic equations of mathematical physics (for instance function of two independent variables) is the differential equation with partial derivatives of the second order (3). This equation is called the wave equation, and is provided when considering the process of transverse oscillations of wire, longitudinal oscillations of rod, electrical oscillations in a conductor, torsional vibration at waves, etc… The paper shows how to form the equation (3) which is the equation of motion of each point of wire with abscissa x in time t during its oscillation. It is also shown how to determine the equation (3) in the task of electrical oscillations in a conductor. Then equation (3) is determined, and this solution satisfies the boundary and initial conditions. [ABSTRACT FROM AUTHOR]

Copyright of Chemical Industry / Hemijska Industrija is the property of Association of Chemical Engineers and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)