Prof. Andrzej Dziembowski of the PAS Institute of Biochemistry and Biophysics, laureate of this year’s Prize of the Foundation for Polish Science (FNP), talks about RNA-degrading enzymes, the role of yeast in studies that help humans, and two different types of scientists.
Polychlorinated biphenyls (PCBs) are one group of persistent organic pollutants (POPs) that are of international concern because of global distribution, persistence, and toxicity. Removal of these compounds from the environment remains a very difficult challenge because the compounds are highly hydrophobic and have very low solubility in water. A 900 W domestic microwave oven, pyrex vessel reactor, pyrex tube connector and condensing system were used in this experiment. Radiation was discontinuous and ray powers were 540, 720 and 900 W. The PCBS were analyzed by GC-ECD. The application of microwave radiation and H2O2/TiO2 agents for the degradation of polychlorinated biphenyl contaminated oil was explored in this study. PCB – contaminated oil was treated in a pyrex reactor by microwave irradiation at 2450 MHz with the addition of H2O2/TiO2. A novel grain TiO2 (GT01) was used. The determination of PCB residues in oil by gas chromatography (GC) revealed that rates of PCB decomposition were highly dependent on microwave power, exposure time, ratio to solvent with transformer oil in 3:1, the optimal amount of GT01 (0.2 g) and 0.116 mol of H2O2 were used in the study. It was suggested that microwave irradiation with the assistance of H2O2/TiO2 might be a potential technology for the degradation of PCB – contaminated oil. The experiments show that MW irradiation, H2O2 oxidant and TiO2 catalyst lead to a degradation efficiency of PCBs only in the presence of ethanol. The results showed that the addition of ethanol significantly enhanced degradation efficiency of PCBs.
In accordance with the principles of conducting revitalization activities specified in the Revitalization Act in force from 9 October 2015 and horizontal guidelines for revitalization in operational programs for 2014-2020, the preparatory phase of the revitalization process should include multi-layered analyzes concluded with deductions included in communal urban regeneration programs. The article describes the role of student architectural and urban competitions performed in cooperation between municipalities and universities as innovative analytical and conceptual activities that could form the basis for specifying recommendations in revitalization strategies planned by a given municipality. The infl uence of the student competitions’ results on the development of the city revitalization strategy is presented on grounds of periodic competitions organized at the Faculty of Architecture of the Gdańsk University of Technology in cooperation with the Department of Plans and Marketing of the City Hall of the City of Gdańsk.
The aim of the presented work is to prove that construction of large sports facilities in the urban space, can generate positive changes and revitalization of degraded areas. On the basis of comparative analysis of cases in which such activities took place, it can be concluded that locating these facilities in heavily degraded urban areas is one of the most eff ective methods of large-scale revitalization. This is mainly visible in post-industrial areas, which are usually well linked to canals, rivers and other waterways or reservoirs. The vast spaces around sports facilities create favorable conditions for additional recreational functions, such as parks and green areas, which in connection with water become a very attractive place for the residents of the city. Increasing interest in the area leads to new investments such as housing estates and gradual development of a multi-functional urban structure. One of the most important factors leading to this type of transformation is the modernization of the communication infrastructure which enables connection between revitalized areas and the rest of the city. A well-planned program of newly emerging sports facilities is also an extremely important factor. As research shows, large multifunctional sports and entertainment facilities, can function as a new kind of public space in the city. This leads not only to the establishment of completely new social relations, but also to the creation of jobs and the general improvement of the broadly understood image of the district.
In this study, X-ray diffraction, thermogravimetric analysis and differential scanning calorimetry (DSC) method were used to analyze the main characteristics of sweet potato starch, and to analyze the thermal degradation process of sweet potato starch. Specifically, X-ray diffraction to study its structure, thermogravimetric analysis to study the thermal degradation kinetics, and differential scanning calorimetry to study the thermogram of sweet potato starch. The thermal decomposition kinetics of sweet potato starch was examined within different heating rates in nitrogen atmosphere. Different models of kinetic analysis were used to calculate the activation energies using thermogravimetric data of the thermal degradation process. Activation energies obtained from Kissinger, Flynn-Wall- Ozawa, and Šatava-Šesták models were 173.85, 174.87 and 174.34 kJ/mol, respectively. The values of activation energy indicated that the thermal degradation of the sweet potato starch was a single reaction mechanism or the combination of multi-reaction mechanisms. The differential scanning calorimetry analysis show that two decomposition stages were presented: the first at a low temperature involves the decomposition of long chain; and the second at a high temperature represents the scission of glucose ring. This information was helpful to design the processing process of many natural polymers. Thermogravimetric Fourier transform-infrared (TG–FTIR) analysis showed that the main pyrolysis products included water, methane, carbon dioxide, ammonia, and others.
For the reliable applications of silver nanowires, AgNW, which is used as a conductive transparent film in electronic devices, the isothermal degradation behaviors of AgNW films with and without overcoating were investigated. Accelerated isothermal degradation was performed as a function of temperature, time, and atmosphere. Electrical resistance and optical transmittance were measured and correlated with the microstructural damages, such as formation of oxide particles and fragmentations of AgNW, which were quantitatively determined from the scanning electron micrographs. The overcoating retarded the formation of oxide particles and subsequent fragmentations as well as resulting degradation in electrical resistance without affecting the optical transmittance.
The subject of investigations was the fragment of low peatland complex located close to Miękinia, about 30 km from Wrocław. Within the range of the examined area of peat bog complex there can be distinguished three parts differing in their utilization and composition of species, namely: 1/ the area degraded by the attempt to afforest it with alder trees Alnus glutinosa (L.) Gaertner, 2/ occasionally used bog hay meadow and 3/ typical peat forming phytocenosis. Total number of determined species, belonging to 11 phytosociological classes, ranged 77, out of which more than a half constitute representatives of Molinio-Arrhenatheretea class. As far as a non-afforested area was concerned, there were determined 5 phytocenosis, including 4 classified as peat forming ones and one typical for post-bog meadows (Alopecuretum pratensis). The afforested area featured herbaceous plant composition which indicated that the area with Alopecuretum pratensis phytocenosis had been degraded. Analysis of environmental requirements, done with the use of ecological numbers, proved that prevailing number of species characterize similar requirements. It was mainly afforested part to feature taxons of broader ecological scale, e.g. Polygonum bistora L., Carex hirta L. and Plantago lanceolata L. The afforested area was purchased by a private person, therefore it can be assumed that the reason for such a way of peatlands utilization was obtaining EU subsidies at minimum work effort. A higher financial profit, however, would have been made by the owner if he had maintained a bog area as an extensive meadow.
The focus of this study is to investigate the applicability of natural mineral iron disulﬁde (pyrite) in degradation of aromatic compounds including benzene and several chlorinated benzenes (from mono-chlorinated benzene (CB), di-chlorinated benzenes (di-CBs) to tri-chlorobenzenes (tri-CBs) in aerobic pyrite suspension by using laboratory batch experiments at 25°C and room pressure. At ﬁrst, chlorobenzene was studied as a model compound for all considered aromatic compounds. CB was degraded in aerobic pyrite suspension, transformed to several organic acids and ﬁnally to CO2 and Cl-. Transformations of remaining aromatic compounds were pursued by measuring their degradation rates and CO2 and Cl- released with time. Transformation kinetics was ﬁtted to the pseudo-ﬁrst-order reactions to calculate degradation rate constant of each compound. Degradation rates of the aromatic compounds were different depending on their chemical structures, speciﬁcally the number and position of chlorine substituents on the benzene ring in this study. Compounds with the highest number of chlorine substituent at m-positions have highest degradation rate (1,3,5-triCB > 1,3-diCB > others). Three chlorine substituents closed together (1,2,3-triCB) generated steric hindrance effects. Therefore 1,2,3-triCB wasthe least degraded compound. The degradation rates of all compounds were in the following order: 1,3,5-triCB > 1,3-diCB > 1,2,4-triCB ≅ 1,2-diCB ≅ CB ≅ benzene > 1,4-diCB > 1,2,3-triCB. The ﬁnal products of the transformations were CO2 and Cl-. Oxygen was the common oxidant for pyrite and aromatic compounds. The presence of aromatic compounds reduced the oxidation rate of pyrite, which reduced the amount of ferrous and sulfate ions release to aqueous solution.
The paper presents the response of a three-layered annular plate with damaged laminated facings to the loads acting in their planes. The presented problem concerns the analysis of the combination of global plate failure in the form of buckling with the local micro defects, like fibre or matrix cracks, located in the laminas. The plate structure consists of thin laminated, fibre-reinforced composite facings and a thicker foam core. The matrix and fibre cracks of facings laminas can be transversally symmetrically or asymmetrically located in plate structure. Critical static and dynamic stability analyses were carried out solving the problem numerically and analytically. The numerical results show the static and dynamic stability state of the composite plate with different combinations of damages. The final results are compared with those for undamaged structure of the plate and treated as quasi-isotropic ones. The analysed problem makes it possible to evaluate the use of the non-ideal composite plate structure in practical applications.
The paper presents the test results for the microstructure of ZnO varistors comprising high voltage gapless surge arresters. The tests were performed on varistors produced in different periods and by various manufacturers. The research was inspired by different characteristics of changes in values of current flowing through surge arresters as a function of changes in values of system voltage in a 220 kV substation, and the temperature in a multi-year cycle. Furthermore, the effects of varistor microstructure degradation following a failure of an unsealed surge arrester were investigated. The results provided the grounds for assessment of ZnO varistor microstructure parameters in terms of their durability and resistance to degradation processes.
A proper management of sand grains of moulding sands requires knowing basic properties of the spent matrix after casting knocking out. This information is essential from the point of view of the proper performing the matrix recycling process and preparing moulding sands with reclaimed materials. The most important parameter informing on the matrix quality – in case of moulding sands with organic binders after casting knocking out – is their ignition loss. The methodology of estimating ignition loss of spent moulding sands with organic binder– after casting knocking out - developed in AGH, is presented in the paper. This method applies the simulation MAGMA software, allowing to determine this moulding sand parameter already at the stage of the production preparation.
A determination of the heating degree of the moulding sand with bentonite on the grounds of simulating investigations with the application of the MAGMA program, constitutes the contents of the paper. To this end the numerical simulation of the temperature distribution in the virtual casting mould was performed. It was assumed that the mould cavity was filled with a moulding sand with bentonite of a moisture content 3,2 % and bentonite content 8 %. A computer simulation can be used for predicting the heating degree of moulding sands with bentonite. Thus, prediction of the active bentonite (montmorillonite) content in individual layers of the overheated moulding sand can be done by means of the simulation. An overheating degree of a moulding sand with bentonite, and thus the bentonite deactivation depends on a temperature of a casting alloy, casting mass, ratio of: masssand : masscasting, moulding sand amount in the mould and contact area: metal – mould (geometry of the casting shape). Generally it can be stated, that the bentonite deactivation degree depends on two main factors: temperature of moulding sand heating and time of its operation.
This paper studies the assessment of sensitivity to land degradation of Deliblato sands (the northern part of Serbia), as a special nature reserve. Sandy soils of Deliblato sands are highly sensitive to degradation (given their fragility), while the system of land use is regulated according to the law, consisting of three zones under protection. Based on the MEDALUS approach and the characteristics of the study area, four main factors were considered for evaluation: soil, climate, vegetation and management. Several indicators affecting the quality of each factor were identified. Each indicator was quantified according to its quality and given a weighting of between 1.0 and 2.0. ArcGIS 9 was utilized to analyze and prepare the layers of quality maps, using the geometric mean to integrate the individual indicator map. In turn, the geometric mean of all four quality indices was used to generate sensitivity of land degradation status map. Results showed that 56.26% of the area is classified as critical; 43.18% as fragile; 0.55% as potentially affected and 0.01% as not affected by degradation. The values of vegetation quality index, expressed as coverage, diversity of vegetation functions and management policy during the protection regime are clearly represented through correlation coefficient (0.87 and 0.47).
This article presents the evolution of the approach to the indicative designation of revitalization areas in Poland at central, regional and local level. The introduction shows rational for monitoring of degradation in Polish cities, i.e. a continuous assessment of its condition, and not just the designation of areas where intervention is needed. Monitoring ensures the comparability of observations and allows to evaluate the results of undertaken measures. Without it, it is impossible to fully assess the effects of revitalization in the previous financial perspectives. The first chapter of the article outlines the requirements for determining areas for revitalization before 2013, the reasons for their adoption, and the indicators used in the delimitations at the time. The second chapter contains the results of a study carried out in the fi rst half of 2016 at the Institute of Urban Development concerning the designation of degraded areas and revitalization areas just after the entry into force of the revitalization law. The results of the study are conclusions confirming the use of cities, which first delimited the areas of revitalization from the possibility of individualizing the approach to the designation of those areas, which was introduced by the Guidelines and the law.
In this paper the basic methodology of the coupled response-degradation modelling of stochastic dynamical systems is presented along with the effective analysis of selected problems. First, the general formulation of the problems of stochastic dynamics coupled with the evolution of deterioration process is given. Then some specific degrading oscillatory systems under random excitation are analyzed with a special attention on the systems with fatigue-induced stiffness degradation. Both, the general discussion and the analysis of selected exemplary problems indicate how the reliability of deteriorating stochastic dynamical systems can be assessed.
Results of the investigation of thermal degradation of polyolefins in the laboratory-scale set-up reactors are presented in the paper. Melting and cracking processes were carried out in two different types of reactors at the temperature of 390-420°C. This article presents the results obtained for conversion of polyolefin waste in a reactor with a stirrer. Next, they were compared with the results obtained for the process carried out in a reactor with a molten metal bed, which was described in a previous publication. For both processes, the final product consisted of a gaseous (2-16 % mass) and a liquid (84-98 % mass) part. No solid product was produced. The light, "gasoline" fraction of the liquid hydrocarbons mixture (C4-C10) made up over 50% of the liquid product. The overall (vapor) product may be used for electricity generation and the liquid product for fuel production.
The paper presents investigations of microstructure of varistors of damaged surge arrester counters. A similar ZnO varistor, not subjected before to operation, was a point of reference in this research. The results of investigations of the ZnO varistors show an untypical phase composition of their material, which was characterized by unsatisfying homogeneity and cohesion. The degradation processes of varistor material in the subsequent stages were recognized and described. A harmful impact of humidity inside the untight surge arrester counter on its operation and its ZnO varistors was proved. Some conclusions being the result of the operation checking of surge arrester counters were presented too.
This experimental paper comprises the results of acoustic emission (AE), microscopic and ultrasonic measurements of samples subjected to slowly increasing compressive stress. On the basis of conducted measurements the successive stages of the material structural degradation have been recognized. The objects of study were samples made of C 120 aluminous porcelain. The investigated material has found at present the application in the fabrication of technical elements like overhead power line insulators. In the case of such objects, not only high mechanical strength, but especially elevated durability as well as operational reliability are required. The expected "life time" of net insulators during exploitation is about 40 years. The analysis of obtained mechanoacoustic dependences pointed out a complex mechanism of degradation of the material. Microscopic investigation of samples, which were stressed to different levels of load, enabled to specify the development of gradual growth of microcracks and successive crushing out of elements of the structure. These processes appear to be similar to the ageing processes occurring in the material during long period of exploitation under a working load. Three stages of the structure degradation were distinguished. The preliminary and subcritical ones show low or moderate intensity of AE signals and considerable variety for the particular samples. The critical stage directly precedes the destructtion of samples. Its range is relatively narrow and reveals the AE activity of high energy. The effectiveness of dispersive and fibrous reinforcement of modern aluminous porcelain C 120 type has been described. Structural strengthening by corundum grains and mullite needle shaped crystals improves mechanical parameters and distinguishes this material from typical aluminosilicate ceramics. The presented results enable drawing up the conclusions concerning the resistance of investigated material to the ageing degradation process development during long term operation.
Magnetic circuits of electromagnetic energy converters, such as electrical machines, are nowadays highly utilized. This proposition is intrinsic for the magnetic as well as the electric circuit and depicts that significant enhancements of electrical machines are difficult to achieve in the absence of a detailed understanding of underlying effects. In order to improve the properties of electrical machines the accurate determination of the locally distributed iron losses based on idealized model assumptions solely is not sufficient. Other loss generating effects have to be considered and the possibility being able to distinguish between the causes of particular loss components is indispensable. Parasitic loss mechanisms additionally contributing to the total losses originating from field harmonics, non-linear material behaviour, rotational magnetizations, and detrimental effects caused by the manufacturing process or temperature, are not explicitly considered in the common iron-loss models, probably even not specifically contained in commonly used calibration factors. This paper presents a methodology being able to distinguish between different loss mechanisms and enables to individually consider particular loss mechanisms in the model of the electric machine. A sensitivity analysis of the model parameters can be performed to obtain information about which decisive loss origin for which working point has to be manipulated by the electromagnetic design or the control of the machine.
In this article I will attempt to answer the question of why systemic solutions to (social) problems of Polish economic migrants fail to be instituted in Poland by means of social negotiations. Therefore, while emphasising the social dimension of Polish migration, I briefly present its specificity and point to some associated threats. Referring to the category labelled as social problem, I demonstrate the nature of obstacles which prevent a debate on Polish migration in the area of social negotiations from taking root on public ground in Poland. I also refer to the mechanisms of degradation of the public sphere as those which are preventing the development of systemic solutions to the problems of Polish migrant workers by means of social negotiations.
In the paper the reasons for steam pipeline’s elbow material rupture, made of steel 13CrMo4-5 (15HM) that is being used in the energetics. Based on the mechanical properties in the ambient temperature (Rm, Rp0,2 and elongation A5) and in the increased temperature (Rp0,2t ) it was found, that the pipeline elbow’s material sampled from the ruptured area has lower Rp0,2 i Rp0,2t by around 2% than it is a requirement for 13CrMo4-5 steel in it’s base state. The damage appeared as a result of complex stress state, that substantially exceeded the admissible tensions, what was the consequence of considerable structure degradation level. As a result of the microstructure tests on HITACHI S4200 microscope, the considerable development of the creeping process associates were found. Also the advances progress of the microstructure degradation was observed, which is substantial decomposition of bainite and multiple, with varied secretion size, and in most cases forming the micro cracks chains. With the use of lateral micro sections the creeping voids were observed, that creates at some places the shrinkage porosities clusters and micro pores.