We analysed the photooxidation reaction in the electro-(1O2) and nucleophilic (O2•−) reaction of 2-pyridone azo derivatives. First, we calculated the energy (enthalpies) of tautomers formation, which is a measure of d...We analysed the photooxidation reaction in the electro-(1O2) and nucleophilic (O2•−) reaction of 2-pyridone azo derivatives. First, we calculated the energy (enthalpies) of tautomers formation, which is a measure of durability and the probability of their formation. We performed the light fastness calculations of the monoazopyridone dyes. Using the semi-empirical methods of quantum chemistry AM1 and PM3, the reactivity indicators of superdelocalisability (SrE(N)) and the electron density distribution in ground state on the highest occupied HOMO orbital and the lowest unoccupied excited state LUMO in 2-pyridone phenylazo derivatives were calculated. Superdelocalisability coefficients enable the stability to oxidising agents of various chemical molecules depending on the tautomeric forms in which they may occur. The results of the electron density calculations at the HOMO and LUMO boundary orbitals allow to determine the tendency to electrophilic attack with singlet oxygen 1O2 or nucleophilic attack of the superoxide anion O2•−on a specific atom in the molecule. The structure of the dyes was optimised with MM+, MD and AM1 or PM3 until a constant energy value was achieved with a convergence criterion of 0.01 kcal/mol.展开更多
Behind armour blunt trauma(BABT)is a body injury resulting from the deformation of the back surface of armour as a result of a bullet impact.In the case of textile body armour,the severity of the injury may depend on ...Behind armour blunt trauma(BABT)is a body injury resulting from the deformation of the back surface of armour as a result of a bullet impact.In the case of textile body armour,the severity of the injury may depend on the material of the fibres,but also on the geometric structure of the fabric.The article focuses on experimental research into injuries of the human body protected by ballistic packets made of biaxial and triaxial fabrics,during a non-penetrating impact from a Parabellum 9 mm×19 mm Full Metal Jacket(FMJ)bullet,at a speed of 406±5 m/s.In experimental research,the fabrics had a comparable surface weight and were made of the same Kevlar^(■)29 yarn.The ballistic packages were made of 30 layers.As part of the work,a physical model of the human body was developed.The human body model consisted of a model of the heart,lungs,and skeletal and muscular systems.During the bullet impact,the pressure forces were recorded using sensors located at selected points of the human body.The bullets hit five selected places on the body that were considered critical,from the point of view of maintaining a human’s vital functions.It was found that,during firing,pressure increases both at the site of impact and in the internal organs,which can lead to multi-organ damage.As a result of the experimental analysis,it has been shown that the pressures exerted on specific organs are always lower in the case of body protection with a ballistic packet made of triaxial fabrics,compared to a packet made of biaxial fabrics.展开更多
Molecular dynamics(MD)simulation is a computational technique that analyzes the movement of a system of particles over a given period.MD can provide detailed information about the fluctuations and conformational chang...Molecular dynamics(MD)simulation is a computational technique that analyzes the movement of a system of particles over a given period.MD can provide detailed information about the fluctuations and conformational changes of biomolecules at the atomic level over time.In recent years,MD has been widely applied to the discovery of peptides and peptide-like molecules that may serve as severe acute respiratory syndrome coronavirus 2(SARS-CoV-2)inhibitors.This review summarizes recent advances in such explorations,focusing on four protein targets:angiotensin-converting enzyme 2(ACE2),spike protein(S protein),main protease(M^(pro)),and papain-like protease(PL^(pro)).These four proteins are important druggable targets of SARS-CoV-2 because of their roles in viral entry,maturation,and infectivity of the virus.A review of the literature revealed that ACE2,S protein,and M^(pro) have received more attention in MD research than PL^(pro).Inhibitors of the four targets identified by MD simulations included peptides derived from food and other bioresources,peptides designed using the targets as templates,and peptide-like molecules retrieved from databases.Many of the inhibitors have yet to be validated in experimental assays for potency.Nevertheless,the role of MD simulation as an efficient tool in the early stages of anti-SARS-CoV-2 drug discovery agents has been demonstrated.展开更多
The computational techniques are a set of novel problem-solving methodologies that have attracted wider attention for their excellent performance.The handling strategies of real-world problems are artificial neural ne...The computational techniques are a set of novel problem-solving methodologies that have attracted wider attention for their excellent performance.The handling strategies of real-world problems are artificial neural networks(ANN),evolutionary computing(EC),and many more.An estimated fifty thousand to ninety thousand new leishmaniasis cases occur annually,with only 25%to 45%reported to the World Health Organization(WHO).It remains one of the top parasitic diseases with outbreak and mortality potential.In 2020,more than ninety percent of new cases reported to World Health Organization(WHO)occurred in ten countries:Brazil,China,Ethiopia,Eritrea,India,Kenya,Somalia,South Sudan,Sudan,and Yemen.The transmission of visceral leishmaniasis is studied dynamically and numerically.The study included positivity,boundedness,equilibria,reproduction number,and local stability of the model in the dynamical analysis.Some detailed methods like Runge Kutta and Euler depend on time steps and violate the physical relevance of the disease.They produce negative and unbounded results,so in disease dynamics,such developments have no biological significance;in other words,these results are meaningless.But the implicit nonstandard finite difference method does not depend on time step,positive,bounded,dynamic and consistent.All the computational techniques and their results were compared using computer simulations.展开更多
The application of fuzzy theory is vital in all scientific disciplines.The construction of mathematical models with fuzziness is little studied in the literature.With this in mind and for a better understanding of the...The application of fuzzy theory is vital in all scientific disciplines.The construction of mathematical models with fuzziness is little studied in the literature.With this in mind and for a better understanding of the disease,an SEIR model of malaria transmission with fuzziness is examined in this study by extending a classicalmodel ofmalaria transmission.The parametersβandδ,being function of the malaria virus load,are considered fuzzy numbers.Three steady states and the reproduction number of the model are analyzed in fuzzy senses.A numerical technique is developed in a fuzzy environment to solve the studied model,which retains essential properties such as positivity and dynamic consistency.Moreover,numerical simulations are carried out to illustrate the analytical results of the developed technique.Unlike most of the classical methods in the literature,the proposed approach converges unconditionally and can be considered a reliable tool for studying malaria disease dynamics.展开更多
The human immunodeficiency viruses are two species of Lentivirus that infect humans.Over time,they cause acquired immunodeficiency syndrome,a condition in which progressive immune system failure allows life-threatening ...The human immunodeficiency viruses are two species of Lentivirus that infect humans.Over time,they cause acquired immunodeficiency syndrome,a condition in which progressive immune system failure allows life-threatening opportunistic infections and cancers to thrive.Human immunodeficiency virus infection came from a type of chimpanzee in Central Africa.Studies show that immunodeficiency viruses may have jumped from chimpanzees to humans as far back as the late 1800s.Over decades,human immunodeficiency viruses slowly spread across Africa and later into other parts of the world.The Susceptible-Infected-Recovered(SIR)models are significant in studying disease dynamics.In this paper,we have studied the effect of irresponsible immigrants on HIV/AIDS dynamics by formulating and considering different methods.Euler,Runge Kutta,and a Non-standardfinite difference(NSFD)method are developed for the same problem.Numerical experiments are performed at disease-free and endemic equilibria points at different time step sizes‘ℎ’.The results reveal that,unlike Euler and Runge Kutta,which fail for large time step sizes,the proposed Non-standardfinite difference(NSFD)method gives a convergence solution for any time step size.Our proposed numerical method is bounded,dynamically con-sistent,and preserves the positivity of the continuous solution,which are essential requirements when modeling a prevalent disease.展开更多
Differential heat of absorption of CO_2 in aqueous solutions of N,N-diethylethanolamine(DEEA) and activated DEEA solutions up to a total concentration of 2 mol·L^(-1) was measured as a function of CO_2 loading at...Differential heat of absorption of CO_2 in aqueous solutions of N,N-diethylethanolamine(DEEA) and activated DEEA solutions up to a total concentration of 2 mol·L^(-1) was measured as a function of CO_2 loading at 313.15 K using a reaction calorimeter. In order to analyze the performance of N-methyl-1,3-propanediamine(MAPA)as an activator, DEEA blended solutions containing 0.05, 0.1 and 0.2 mol·L^(-1) MAPA were studied. The heat of CO_2 absorption in single DEEA solutions was unaffected by changing the DEEA concentration in the range of(0.5–2) mol·L^(-1). On the other hand, increasing the concentration of MAPA in aqueous amine mixtures of(DEEA + MAPA) raised the heat of absorption.展开更多
Access to natural resources is increasingly more difficult and more costly, partly due to their economic significance and to continuous increase of their global consumption in the recent years. In the case of phosphor...Access to natural resources is increasingly more difficult and more costly, partly due to their economic significance and to continuous increase of their global consumption in the recent years. In the case of phosphorus (P), which is a critical raw material, geological distribution of its primary nonrenewable source (phosphate rock) is concentrated in particular regions leading to high supply risk of this raw material. In Europe (EU-28), where phosphate rock reserves are scarce, import of phosphorus has been the main source of supply. It means that Europe relies highly on the foreign exporters. From decision makers' perspective, recycling of phosphorus was taken into account as one of the possible solutions to decrease the dependence on imports and extraction of reserves. The question, however, is to what extent does the recycling of phosphorus help in reducing the reliance on typical supply resources? Hence, the main objective of this paper is to quantify the dynamic flow of phosphorus and show potential benefits of its recycling in Europe. This article presents a system dynamics model for representation of the element P flow and helps to quantify to what extent the recycled phosphorus could mitigate its criticality. Analysis of the results supports previous studies indicating the high reliance ofEU on P imports, estimating around 96% as the reliance percentage on imports. The results imply that improving P recycling has the potential to decrease the level of P imports to a certain extent, which may reach 79%.展开更多
The authors evaluated the frequency of exposure to tobacco smoke among children suffering from respiratory tract infections. The investigations comprised 141 children aged from 2 months to 6 years that were treated in...The authors evaluated the frequency of exposure to tobacco smoke among children suffering from respiratory tract infections. The investigations comprised 141 children aged from 2 months to 6 years that were treated in the 2nd Department of Pediatric and Allergology of Polish Mother’s Memorial Hospital Research Institute in ?ód? (Poland). 69 of them were exposed to tobacco smoke in their home environment. The remaining 72 children came from non-smoking families. 26 (37.7%) individuals among the passive smokers and 15 (20.83%) among the children from non-smoking families suffered from recurrent respiratory tract infections. Cotinine concentrations were evaluated in the group of 69 children using the HPLC-UV method. The determined average cotinine/creatinine index expressed as median was higher in passive smokers with recurrent respiratory infections than among passive smokers with non-recurrent respiratory infections. Moreover, it was stated that the exposure to cigarette smoke was more often among children of younger and less well educated parents as well as living in poor housing conditions. These studies clearly indicate that there is a need for extensive education on the harmful effects of passive smoking and the recurrence of infections.展开更多
Novel elastomer biocomposites based on straw fibers (raw or chemically modified) as reinforcing elements ofnatural rubber (NR) were reported and studied. Oat straw fibres with different average lengths were used.Ligno...Novel elastomer biocomposites based on straw fibers (raw or chemically modified) as reinforcing elements ofnatural rubber (NR) were reported and studied. Oat straw fibres with different average lengths were used.Lignocellulose materials were incorporated into the elastomer, before and after chemical surface modificationinvolving sodium hydroxide. Fourier transform infrared spectroscopy (FTIR) and microscopy techniques wereemployed for characterization of fillers. The kinetics of rubber mixtures, as well as rheometric properties ofcompounds were determined. The cross-linking density was executed on the basis of equilibrium solventswellingmeasurements applying the modified Flory–Rehner equation. The morphology of biocompositessamples was analyzed by a scanning electron microscopy. Mechanical characteristic: the values of hardness,tensile strength and attenuation coefficient were also determined. The physical and chemical investigations haveproved the reinforcing effect of treated oat straw on natural rubber vulcanizates.展开更多
The objective of this study is to investigate the outcomes of co-branding strategy in the assessment of the brand managers of analysed companies on European market and verification if a co-branding gives the opportuni...The objective of this study is to investigate the outcomes of co-branding strategy in the assessment of the brand managers of analysed companies on European market and verification if a co-branding gives the opportunities for internal and external development. The analysis of correlation between the outcomes of co-branding and two major categories of co-branding strategy (ingredient branding and symbolic co-branding) are also important. In the paper the results of empirical studies are presented. Recent primary research (2009-2011) was conducted in 50 companies which are present in minimum three countries of Europe and have realized co-branding strategy for three years. Questionnaire surveys were carried out throughout all 120 identified companies. As a result, data from 50 companies were obtained, which amounted to 41.7% of all companies polled. The analysis of findings indicates the different outcomes in case of two major categories of co-branding strategy. The results show the general evaluation of the co-branded projects as well as the possibilities of the internal and external development. The results also emphasize the significance of symbolic character of the co-branding strategy. The recommendations in this study are set forth, of course, with the caveat as to the limitations of the sample. Nonetheless, it is believed that the results of this study will alert companies to the potential outcomes of co-branding taking into account the category of cooperation. This research has resulted in practical contribution. From the substantive stand point, this research has shed light on the outcomes of co-branding. This information can be useful for managers to understand which effects can be expected. From a theoretical and practical standpoint, this research contributes to brand alliances research and has provided a better understanding of outcomes of co-branding and the correlations between the possibilities of internal and external development and chosen category of co-branding strategy. This text may contribute to further research in this area and as a kind of motivator for further discussion on this topic.展开更多
The paper presents results of reliability analysis made for lignite fired 370 MW rated power units installed in the Belchatow Power Plant (Poland). The concept of standardized power unit and the method of a histogram ...The paper presents results of reliability analysis made for lignite fired 370 MW rated power units installed in the Belchatow Power Plant (Poland). The concept of standardized power unit and the method of a histogram with a set number of observations in each class were applied in a study. The study includes analysis of probability distributions of operation times and repair times for the main power unit components. Empirical probability distribution functions have been identified and their parameters estimated in the study. The final forecast includes an estimation of such reliability measures like expected operation time, expected failure rate, average repair time and expected annual failure duration.展开更多
A comparison of thermal and photochemical degradation of poly (lactic acid) film materials (10/am) containing nanosilver are studied by FTlR (Fourier transform infrared) spectroscopy and DSC (differential scann...A comparison of thermal and photochemical degradation of poly (lactic acid) film materials (10/am) containing nanosilver are studied by FTlR (Fourier transform infrared) spectroscopy and DSC (differential scanning calorimetry). Rates of thermal and photochemical degradation are determined by measuring the relative changes of absorbance (A/Ao) of selected bands in PLA (polylactic acid) spectra. Comparison of the effect of both degradation on PLA structure showed that nanosilver act as a stabilizer for photodegradation at 254 nm. As oppose, thermal degradation at 80 ~C indicate, that nanosilver accelerates PLA degradation at the temperature. Glass transition and crystallization/melting processes occurring in PLA and PLA/Ag nanocomposites during both degradation processes were also compared.展开更多
This paper describes possibility of utilization of waste natural fibres in production of sound absorbing composites. Waste flax fibres were modified by enzymatic treatment, after which they became more short and fine....This paper describes possibility of utilization of waste natural fibres in production of sound absorbing composites. Waste flax fibres were modified by enzymatic treatment, after which they became more short and fine. This form of fibres can create good sound absorption. Preliminary studies concerned an application of cellulose fibres after enzymatic treatment as the filling of thermoplastic sound absorbing composites. The conditions of composite manufacturing process from multilayer structure (matrix nonwoven/submicrofibres layer) were developed. The influence of submicroflbres content in the composite on the scale of the improvement of its sound absorption property was investigated. Results showed that for the same conditions of the composite manufacturing process and similar composite thickness, gradual increase in content of that filling leads to adequately increase in sound absorption coefficient of the composites. The composites could be applied among others to accommodations and transport facilities.展开更多
In this paper a rotor-stator spinning disk reactor for intensified biodiesel synthesis is described and numerically simulated. The reactor consists of two flat disks, located coaxially and parallel to each other with ...In this paper a rotor-stator spinning disk reactor for intensified biodiesel synthesis is described and numerically simulated. The reactor consists of two flat disks, located coaxially and parallel to each other with a gap ranging from 0.1 mm to 0.2 mm between the disks. The upper disk is located on a rotating shaft while the lower disk is stationary. The feed liquids, triglycerides (TG) and methanol are introduced coaxially along the center line of rotating disk and stationary disk, respectively. Fluid hydrodynamics in the reactor for synthesis of biodiesel from TG and methanol in the presence of a sodium hydroxide catalyst are simulated, using convection-diffusion-reaction species transport model by the CFD software ANSYS? Fluent v. 13.0. The effects of upper disk’s spinning speed and gap size are evaluated.展开更多
This paper presents finite element models of the fingertip skin which have been created to simulate the contact of textile objects with the skin to gain a better understanding of the perception of textiles through the...This paper presents finite element models of the fingertip skin which have been created to simulate the contact of textile objects with the skin to gain a better understanding of the perception of textiles through the skin, the so-called hand of textiles. Many objective and subjective techniques have already been developed for analysing the hand of textiles;however, none of them provide exact overall information concerning the sensation of textiles through the skin. As the human skin is a complex heterogeneous hyperelastic body composed of many particles, some simplifications had to be made at the early stage of building the models;however, their utilitarian value was maintained. The models relate only to mechanical loading of the skin. They predict a low deformation of the fingertip skin under the pressure of virtual heterogeneous material: acrylic, coarse wool, and steel.展开更多
The aim of this article is to find an answer to the question: Does the similarity of the profiles of companies participating in the acquisition influence the post-transaction integration? While creating a research c...The aim of this article is to find an answer to the question: Does the similarity of the profiles of companies participating in the acquisition influence the post-transaction integration? While creating a research concept, a hypothesis was adopted that the range and the dynamics of the post-acquisition integration are higher, if the companies are similar as far as their sizes, structures, life cycles, and organizational cultures are concerned. Five acquisitions from the pharmaceutical sectors were examined. The results presented in this paper are a part of wider research on consolidation processes in the pharmaceutical branch. In each case, the research had a retrospective character. In order to assess the integration activities, the research was conducted three years after the transaction. An inductive analysis of case study type was used and the technique of research triangulation was applied. A part of the research used for the needs of this paper was conducted by the means of two methods: individual in-depth interviews with the presidents/managing directors of the companies which were taken over and panel interviews in which the presidents and managing directors as well as director and managers of the development units, managers of organization as well as the directors/managers of human resource units of the acquired companies participated. The analysis of the profiles of similarity of companies-transaction partners showed that although they belonged to the same branch, the analyzed companies are characterized by a low level of similarity, especially as far as the structures and organizational cultures are concerned. The strategy of functioning after the merger is based in the majority of cases on the model of partnership. It takes for granted a low level of integration referring only to some selected areas and is connected with an adoption of a long-term integration perspective foreseen for a period longer than three years of functioning in the merged structure.展开更多
Comparison of the loss factor determination methods of the sandwich composite structure with polyethylene terephthalate core in the aspect of core material rheological parameters identification was the purpose of the ...Comparison of the loss factor determination methods of the sandwich composite structure with polyethylene terephthalate core in the aspect of core material rheological parameters identification was the purpose of the study. Three frequency bandwidths n dB: 1 dB, 2 dB, 3 dB methods, the resonant amplitude method and the fit method of the response of the one degree of freedom model system are taken into considerations. Identification procedure, according to ASTM E756-2005 [1] based on experimental studies of the forced vibrations of the composite structure was presented in the paper. To determine the function of the complex shear modulus of the core material, the Nelder-Mead method is applied. Shear modulus and loss factor identification results were presented on the plots in the frequency domain. The results in a quantitative manner set the applied methods and their practical utility in order.展开更多
Therapeutics are compounds,which do not always exhibit healing powers.They sometimes prevent or control roles.Many compounds,well known or less are treated as the therapeutic agents.Among them,there is a specific grou...Therapeutics are compounds,which do not always exhibit healing powers.They sometimes prevent or control roles.Many compounds,well known or less are treated as the therapeutic agents.Among them,there is a specific group of molecules named commonly as Schiff bases,chemically imines.Schiff bases are aldehyde-or ketone-like compounds in which the carbonyl group is replaced by an imine-HN=СН-or azomethine-NHN=СН-group,they are an important class of compounds for new drug development.Schiff base modifications so far proved to be very effective with increased efficacy and reduced toxicity.Therefore,many researchers have synthesized these compounds as target structures and evaluated their biological activity.The aim of this work was to present some interesting and promising examples of Schiff bases which exhibit biological activity.展开更多
文摘We analysed the photooxidation reaction in the electro-(1O2) and nucleophilic (O2•−) reaction of 2-pyridone azo derivatives. First, we calculated the energy (enthalpies) of tautomers formation, which is a measure of durability and the probability of their formation. We performed the light fastness calculations of the monoazopyridone dyes. Using the semi-empirical methods of quantum chemistry AM1 and PM3, the reactivity indicators of superdelocalisability (SrE(N)) and the electron density distribution in ground state on the highest occupied HOMO orbital and the lowest unoccupied excited state LUMO in 2-pyridone phenylazo derivatives were calculated. Superdelocalisability coefficients enable the stability to oxidising agents of various chemical molecules depending on the tautomeric forms in which they may occur. The results of the electron density calculations at the HOMO and LUMO boundary orbitals allow to determine the tendency to electrophilic attack with singlet oxygen 1O2 or nucleophilic attack of the superoxide anion O2•−on a specific atom in the molecule. The structure of the dyes was optimised with MM+, MD and AM1 or PM3 until a constant energy value was achieved with a convergence criterion of 0.01 kcal/mol.
文摘Behind armour blunt trauma(BABT)is a body injury resulting from the deformation of the back surface of armour as a result of a bullet impact.In the case of textile body armour,the severity of the injury may depend on the material of the fibres,but also on the geometric structure of the fabric.The article focuses on experimental research into injuries of the human body protected by ballistic packets made of biaxial and triaxial fabrics,during a non-penetrating impact from a Parabellum 9 mm×19 mm Full Metal Jacket(FMJ)bullet,at a speed of 406±5 m/s.In experimental research,the fabrics had a comparable surface weight and were made of the same Kevlar^(■)29 yarn.The ballistic packages were made of 30 layers.As part of the work,a physical model of the human body was developed.The human body model consisted of a model of the heart,lungs,and skeletal and muscular systems.During the bullet impact,the pressure forces were recorded using sensors located at selected points of the human body.The bullets hit five selected places on the body that were considered critical,from the point of view of maintaining a human’s vital functions.It was found that,during firing,pressure increases both at the site of impact and in the internal organs,which can lead to multi-organ damage.As a result of the experimental analysis,it has been shown that the pressures exerted on specific organs are always lower in the case of body protection with a ballistic packet made of triaxial fabrics,compared to a packet made of biaxial fabrics.
文摘Molecular dynamics(MD)simulation is a computational technique that analyzes the movement of a system of particles over a given period.MD can provide detailed information about the fluctuations and conformational changes of biomolecules at the atomic level over time.In recent years,MD has been widely applied to the discovery of peptides and peptide-like molecules that may serve as severe acute respiratory syndrome coronavirus 2(SARS-CoV-2)inhibitors.This review summarizes recent advances in such explorations,focusing on four protein targets:angiotensin-converting enzyme 2(ACE2),spike protein(S protein),main protease(M^(pro)),and papain-like protease(PL^(pro)).These four proteins are important druggable targets of SARS-CoV-2 because of their roles in viral entry,maturation,and infectivity of the virus.A review of the literature revealed that ACE2,S protein,and M^(pro) have received more attention in MD research than PL^(pro).Inhibitors of the four targets identified by MD simulations included peptides derived from food and other bioresources,peptides designed using the targets as templates,and peptide-like molecules retrieved from databases.Many of the inhibitors have yet to be validated in experimental assays for potency.Nevertheless,the role of MD simulation as an efficient tool in the early stages of anti-SARS-CoV-2 drug discovery agents has been demonstrated.
文摘The computational techniques are a set of novel problem-solving methodologies that have attracted wider attention for their excellent performance.The handling strategies of real-world problems are artificial neural networks(ANN),evolutionary computing(EC),and many more.An estimated fifty thousand to ninety thousand new leishmaniasis cases occur annually,with only 25%to 45%reported to the World Health Organization(WHO).It remains one of the top parasitic diseases with outbreak and mortality potential.In 2020,more than ninety percent of new cases reported to World Health Organization(WHO)occurred in ten countries:Brazil,China,Ethiopia,Eritrea,India,Kenya,Somalia,South Sudan,Sudan,and Yemen.The transmission of visceral leishmaniasis is studied dynamically and numerically.The study included positivity,boundedness,equilibria,reproduction number,and local stability of the model in the dynamical analysis.Some detailed methods like Runge Kutta and Euler depend on time steps and violate the physical relevance of the disease.They produce negative and unbounded results,so in disease dynamics,such developments have no biological significance;in other words,these results are meaningless.But the implicit nonstandard finite difference method does not depend on time step,positive,bounded,dynamic and consistent.All the computational techniques and their results were compared using computer simulations.
文摘The application of fuzzy theory is vital in all scientific disciplines.The construction of mathematical models with fuzziness is little studied in the literature.With this in mind and for a better understanding of the disease,an SEIR model of malaria transmission with fuzziness is examined in this study by extending a classicalmodel ofmalaria transmission.The parametersβandδ,being function of the malaria virus load,are considered fuzzy numbers.Three steady states and the reproduction number of the model are analyzed in fuzzy senses.A numerical technique is developed in a fuzzy environment to solve the studied model,which retains essential properties such as positivity and dynamic consistency.Moreover,numerical simulations are carried out to illustrate the analytical results of the developed technique.Unlike most of the classical methods in the literature,the proposed approach converges unconditionally and can be considered a reliable tool for studying malaria disease dynamics.
文摘The human immunodeficiency viruses are two species of Lentivirus that infect humans.Over time,they cause acquired immunodeficiency syndrome,a condition in which progressive immune system failure allows life-threatening opportunistic infections and cancers to thrive.Human immunodeficiency virus infection came from a type of chimpanzee in Central Africa.Studies show that immunodeficiency viruses may have jumped from chimpanzees to humans as far back as the late 1800s.Over decades,human immunodeficiency viruses slowly spread across Africa and later into other parts of the world.The Susceptible-Infected-Recovered(SIR)models are significant in studying disease dynamics.In this paper,we have studied the effect of irresponsible immigrants on HIV/AIDS dynamics by formulating and considering different methods.Euler,Runge Kutta,and a Non-standardfinite difference(NSFD)method are developed for the same problem.Numerical experiments are performed at disease-free and endemic equilibria points at different time step sizes‘ℎ’.The results reveal that,unlike Euler and Runge Kutta,which fail for large time step sizes,the proposed Non-standardfinite difference(NSFD)method gives a convergence solution for any time step size.Our proposed numerical method is bounded,dynamically con-sistent,and preserves the positivity of the continuous solution,which are essential requirements when modeling a prevalent disease.
文摘Differential heat of absorption of CO_2 in aqueous solutions of N,N-diethylethanolamine(DEEA) and activated DEEA solutions up to a total concentration of 2 mol·L^(-1) was measured as a function of CO_2 loading at 313.15 K using a reaction calorimeter. In order to analyze the performance of N-methyl-1,3-propanediamine(MAPA)as an activator, DEEA blended solutions containing 0.05, 0.1 and 0.2 mol·L^(-1) MAPA were studied. The heat of CO_2 absorption in single DEEA solutions was unaffected by changing the DEEA concentration in the range of(0.5–2) mol·L^(-1). On the other hand, increasing the concentration of MAPA in aqueous amine mixtures of(DEEA + MAPA) raised the heat of absorption.
文摘Access to natural resources is increasingly more difficult and more costly, partly due to their economic significance and to continuous increase of their global consumption in the recent years. In the case of phosphorus (P), which is a critical raw material, geological distribution of its primary nonrenewable source (phosphate rock) is concentrated in particular regions leading to high supply risk of this raw material. In Europe (EU-28), where phosphate rock reserves are scarce, import of phosphorus has been the main source of supply. It means that Europe relies highly on the foreign exporters. From decision makers' perspective, recycling of phosphorus was taken into account as one of the possible solutions to decrease the dependence on imports and extraction of reserves. The question, however, is to what extent does the recycling of phosphorus help in reducing the reliance on typical supply resources? Hence, the main objective of this paper is to quantify the dynamic flow of phosphorus and show potential benefits of its recycling in Europe. This article presents a system dynamics model for representation of the element P flow and helps to quantify to what extent the recycled phosphorus could mitigate its criticality. Analysis of the results supports previous studies indicating the high reliance ofEU on P imports, estimating around 96% as the reliance percentage on imports. The results imply that improving P recycling has the potential to decrease the level of P imports to a certain extent, which may reach 79%.
文摘The authors evaluated the frequency of exposure to tobacco smoke among children suffering from respiratory tract infections. The investigations comprised 141 children aged from 2 months to 6 years that were treated in the 2nd Department of Pediatric and Allergology of Polish Mother’s Memorial Hospital Research Institute in ?ód? (Poland). 69 of them were exposed to tobacco smoke in their home environment. The remaining 72 children came from non-smoking families. 26 (37.7%) individuals among the passive smokers and 15 (20.83%) among the children from non-smoking families suffered from recurrent respiratory tract infections. Cotinine concentrations were evaluated in the group of 69 children using the HPLC-UV method. The determined average cotinine/creatinine index expressed as median was higher in passive smokers with recurrent respiratory infections than among passive smokers with non-recurrent respiratory infections. Moreover, it was stated that the exposure to cigarette smoke was more often among children of younger and less well educated parents as well as living in poor housing conditions. These studies clearly indicate that there is a need for extensive education on the harmful effects of passive smoking and the recurrence of infections.
文摘Novel elastomer biocomposites based on straw fibers (raw or chemically modified) as reinforcing elements ofnatural rubber (NR) were reported and studied. Oat straw fibres with different average lengths were used.Lignocellulose materials were incorporated into the elastomer, before and after chemical surface modificationinvolving sodium hydroxide. Fourier transform infrared spectroscopy (FTIR) and microscopy techniques wereemployed for characterization of fillers. The kinetics of rubber mixtures, as well as rheometric properties ofcompounds were determined. The cross-linking density was executed on the basis of equilibrium solventswellingmeasurements applying the modified Flory–Rehner equation. The morphology of biocompositessamples was analyzed by a scanning electron microscopy. Mechanical characteristic: the values of hardness,tensile strength and attenuation coefficient were also determined. The physical and chemical investigations haveproved the reinforcing effect of treated oat straw on natural rubber vulcanizates.
文摘The objective of this study is to investigate the outcomes of co-branding strategy in the assessment of the brand managers of analysed companies on European market and verification if a co-branding gives the opportunities for internal and external development. The analysis of correlation between the outcomes of co-branding and two major categories of co-branding strategy (ingredient branding and symbolic co-branding) are also important. In the paper the results of empirical studies are presented. Recent primary research (2009-2011) was conducted in 50 companies which are present in minimum three countries of Europe and have realized co-branding strategy for three years. Questionnaire surveys were carried out throughout all 120 identified companies. As a result, data from 50 companies were obtained, which amounted to 41.7% of all companies polled. The analysis of findings indicates the different outcomes in case of two major categories of co-branding strategy. The results show the general evaluation of the co-branded projects as well as the possibilities of the internal and external development. The results also emphasize the significance of symbolic character of the co-branding strategy. The recommendations in this study are set forth, of course, with the caveat as to the limitations of the sample. Nonetheless, it is believed that the results of this study will alert companies to the potential outcomes of co-branding taking into account the category of cooperation. This research has resulted in practical contribution. From the substantive stand point, this research has shed light on the outcomes of co-branding. This information can be useful for managers to understand which effects can be expected. From a theoretical and practical standpoint, this research contributes to brand alliances research and has provided a better understanding of outcomes of co-branding and the correlations between the possibilities of internal and external development and chosen category of co-branding strategy. This text may contribute to further research in this area and as a kind of motivator for further discussion on this topic.
文摘The paper presents results of reliability analysis made for lignite fired 370 MW rated power units installed in the Belchatow Power Plant (Poland). The concept of standardized power unit and the method of a histogram with a set number of observations in each class were applied in a study. The study includes analysis of probability distributions of operation times and repair times for the main power unit components. Empirical probability distribution functions have been identified and their parameters estimated in the study. The final forecast includes an estimation of such reliability measures like expected operation time, expected failure rate, average repair time and expected annual failure duration.
文摘A comparison of thermal and photochemical degradation of poly (lactic acid) film materials (10/am) containing nanosilver are studied by FTlR (Fourier transform infrared) spectroscopy and DSC (differential scanning calorimetry). Rates of thermal and photochemical degradation are determined by measuring the relative changes of absorbance (A/Ao) of selected bands in PLA (polylactic acid) spectra. Comparison of the effect of both degradation on PLA structure showed that nanosilver act as a stabilizer for photodegradation at 254 nm. As oppose, thermal degradation at 80 ~C indicate, that nanosilver accelerates PLA degradation at the temperature. Glass transition and crystallization/melting processes occurring in PLA and PLA/Ag nanocomposites during both degradation processes were also compared.
文摘This paper describes possibility of utilization of waste natural fibres in production of sound absorbing composites. Waste flax fibres were modified by enzymatic treatment, after which they became more short and fine. This form of fibres can create good sound absorption. Preliminary studies concerned an application of cellulose fibres after enzymatic treatment as the filling of thermoplastic sound absorbing composites. The conditions of composite manufacturing process from multilayer structure (matrix nonwoven/submicrofibres layer) were developed. The influence of submicroflbres content in the composite on the scale of the improvement of its sound absorption property was investigated. Results showed that for the same conditions of the composite manufacturing process and similar composite thickness, gradual increase in content of that filling leads to adequately increase in sound absorption coefficient of the composites. The composites could be applied among others to accommodations and transport facilities.
文摘In this paper a rotor-stator spinning disk reactor for intensified biodiesel synthesis is described and numerically simulated. The reactor consists of two flat disks, located coaxially and parallel to each other with a gap ranging from 0.1 mm to 0.2 mm between the disks. The upper disk is located on a rotating shaft while the lower disk is stationary. The feed liquids, triglycerides (TG) and methanol are introduced coaxially along the center line of rotating disk and stationary disk, respectively. Fluid hydrodynamics in the reactor for synthesis of biodiesel from TG and methanol in the presence of a sodium hydroxide catalyst are simulated, using convection-diffusion-reaction species transport model by the CFD software ANSYS? Fluent v. 13.0. The effects of upper disk’s spinning speed and gap size are evaluated.
文摘This paper presents finite element models of the fingertip skin which have been created to simulate the contact of textile objects with the skin to gain a better understanding of the perception of textiles through the skin, the so-called hand of textiles. Many objective and subjective techniques have already been developed for analysing the hand of textiles;however, none of them provide exact overall information concerning the sensation of textiles through the skin. As the human skin is a complex heterogeneous hyperelastic body composed of many particles, some simplifications had to be made at the early stage of building the models;however, their utilitarian value was maintained. The models relate only to mechanical loading of the skin. They predict a low deformation of the fingertip skin under the pressure of virtual heterogeneous material: acrylic, coarse wool, and steel.
文摘The aim of this article is to find an answer to the question: Does the similarity of the profiles of companies participating in the acquisition influence the post-transaction integration? While creating a research concept, a hypothesis was adopted that the range and the dynamics of the post-acquisition integration are higher, if the companies are similar as far as their sizes, structures, life cycles, and organizational cultures are concerned. Five acquisitions from the pharmaceutical sectors were examined. The results presented in this paper are a part of wider research on consolidation processes in the pharmaceutical branch. In each case, the research had a retrospective character. In order to assess the integration activities, the research was conducted three years after the transaction. An inductive analysis of case study type was used and the technique of research triangulation was applied. A part of the research used for the needs of this paper was conducted by the means of two methods: individual in-depth interviews with the presidents/managing directors of the companies which were taken over and panel interviews in which the presidents and managing directors as well as director and managers of the development units, managers of organization as well as the directors/managers of human resource units of the acquired companies participated. The analysis of the profiles of similarity of companies-transaction partners showed that although they belonged to the same branch, the analyzed companies are characterized by a low level of similarity, especially as far as the structures and organizational cultures are concerned. The strategy of functioning after the merger is based in the majority of cases on the model of partnership. It takes for granted a low level of integration referring only to some selected areas and is connected with an adoption of a long-term integration perspective foreseen for a period longer than three years of functioning in the merged structure.
文摘Comparison of the loss factor determination methods of the sandwich composite structure with polyethylene terephthalate core in the aspect of core material rheological parameters identification was the purpose of the study. Three frequency bandwidths n dB: 1 dB, 2 dB, 3 dB methods, the resonant amplitude method and the fit method of the response of the one degree of freedom model system are taken into considerations. Identification procedure, according to ASTM E756-2005 [1] based on experimental studies of the forced vibrations of the composite structure was presented in the paper. To determine the function of the complex shear modulus of the core material, the Nelder-Mead method is applied. Shear modulus and loss factor identification results were presented on the plots in the frequency domain. The results in a quantitative manner set the applied methods and their practical utility in order.
文摘Therapeutics are compounds,which do not always exhibit healing powers.They sometimes prevent or control roles.Many compounds,well known or less are treated as the therapeutic agents.Among them,there is a specific group of molecules named commonly as Schiff bases,chemically imines.Schiff bases are aldehyde-or ketone-like compounds in which the carbonyl group is replaced by an imine-HN=СН-or azomethine-NHN=СН-group,they are an important class of compounds for new drug development.Schiff base modifications so far proved to be very effective with increased efficacy and reduced toxicity.Therefore,many researchers have synthesized these compounds as target structures and evaluated their biological activity.The aim of this work was to present some interesting and promising examples of Schiff bases which exhibit biological activity.