Plant responses to glyphosate applied at different doses were examined for one glyphosate resistant (R) and one glyphosate susceptible (S) population of Conyza albida and C. bonarienis. Growth rates and development stages of five R C. albida and three R C. bonarienis populations were also compared with those of their respective S counterparts to investigate the possible impact of the glyphosate resistance trait on their fitness. The GR50 values for C. albida R (3.94−5.22 kg a.i. · ha−1) and S (0.24−0.31 kg a.i. · ha−1) populations were higher than those of C. bonariensis R (0.60−1.51 kg a.i. · ha−1) and S (0.10−0.13 kg a.i. · ha−1). The growth rate (slope b) of one R C. albida population was lower than the respective S and other R populations, while growth rates of most R and S C. bonariensis populations were similar. Some R populations showed inconsistent differences in some development stages when compared to those of the S ones, which cannot be attributed to the glyphosate resistance trait.
The main scientific goal of this work is the presentation of the role of selected geophysical methods (Ground-Penetrating Radar GPR and Electrical Resistivity Tomography ERT) to identify water escape zones from retention reservoirs. The paper proposes a methodology of geophysical investigations for the identification of water escape zones from a retention fresh water lake (low mineralised water). The study was performed in a lake reservoir in Upper Silesia. Since a number of years the administrators of the lake have observed a decreasing water level, a phenomenon that is not related to the exploitation of the object. The analysed retention lake has a maximal depth between 6 and 10 m, depending on the season. It is located on Triassic carbonate rocks of the Muschelkalk facies. Geophysical surveys included measurements on the water surface using ground penetration radar (GPR) and electrical resistivity tomography (ERT) methods. The measurements were performed from watercrafts made of non-metal materials. The prospection reached a depth of about 1 to 5 m below the reservoir bottom. Due to large difficulties of conducting investigations in the lake, a fragment with an area of about 5,300 m 2, where service activities and sealing works were already commenced, was selected for the geophysical survey. The scope of this work was: (1) field geophysical research (Ground-Penetrating Radar GPR and Electrical Resistivity Tomography ERT with geodesic service), (2) processing of the obtained geophysical research results, (3) modelling of GPR and ERT anomalies on a fractured water reservoir bottom, and (4) interpretation of the obtained results based on the modelled geophysical anomalies. The geophysical surveys allowed for distinguishing a zone with anomalous physical parameters in the area of the analysed part of the retention lake. ERT surveys have shown that the water escape zone from the reservoir was characterised by significantly decreased electrical resistivities. Diffraction hyperboles and a zone of wave attenuation were observed on the GPR images in the lake bottom within the water escape zone indicating cracks in the bottom of the water reservoir. The proposed methodology of geophysical surveys seems effective in solving untypical issues such as measurements on the water surface.
The cotton aphid, Aphis gossypii is an economically significant insect pest infesting various important crops and vegetables. The neonicotinoid, acetamiprid was recommended against aphids with excellent results. Resistance emergence and environmental pollution makes acetamiprid a favorable alternative to conventional insecticides. The aims of the present work were to predict acetamiprid resistance risk in A. gossypii, investigate cross resistance to other tested insecticides and explore acetamiprid stability in the absence of selection. A field-collected population from Sharqia governorate, Egypt was selected with acetamiprid. After 16 generations of selection, there was a 22.55-fold increase in LC50 and the realized heritability (h2) of resistance was 0.17. Projected rates of resistance indicated that, if h2 = 0.17 and 50% of the population was killed at each generation, then a tenfold increase in LC50 would be expected in 12.2 generations. If h2 was 0.27 then 7.63 generations would be needed to achieve the same level. In contrast, with h2 of 0.07 it necessitates about 30 generations of selection to reach the same level. Cross resistance studies exhibited that the selected strain showed obvious cross resistance to the other tested neonicotinoid members, moderate cross resistance to alpha-cypermethrin and no cross resistance to pymetrozine. Fortunately, resistance to acetamiprid in the cotton aphid was unstable and resistance reverses the nearby susceptible strain throughout five generations without exposure to acetamiprid. Our results exhibited cotton aphid potential to develop resistance to acetamiprid under continuous selection pressure. The instability of acetamiprid makes A. gossypii amenable to resistance management tactics such as rotation with pymetrozine.
The publication presents the results of examination of selected carburizers used for cast iron production with respect to their electric resistance. Both the synthetic graphite carburizers and petroleum coke (petcoke) carburizers of various chemical composition were compared. The relationships between electrical resistance of tested carburizers and their quality were found. The graphite carburizers exhibited much better conductivity than the petcoke ones. Resistance characteristics were different for the different types of carburizers. The measurements were performed according to the authors’ own method based on recording the electric current flow through the compressed samples. The samples of the specified diameter were put under pressure of the gradually increased value (10, 20, 50, 60, and finally 70 bar), each time the corresponding value of electric resistance being measured with a gauge of high accuracy, equal to 0.1μΩ. The higher pressure values resulted in the lower values of resistance. The relation between both the thermal conductance and the electrical conductance (or the resistance) is well known and mentioned in the professional literature. The results were analysed and presented both in tabular and, additionally, in graphic form.
In spite of the fact that in most applications, magnesium alloys are intended for operation in environments with room temperature, these alloys are subject to elevated temperature and oxidizing atmosphere in various stages of preparation (casting, welding, thermal treatment). At present, the studies focus on development of alloys with magnesium matrix, intended for plastic forming. The paper presents results of studies on oxidation rate of WE43 and ZRE1 magnesium foundry alloys in dry and humidified atmosphere of N2+1%O2. Measurements of the oxidation rate were carried out using a Setaram thermobalance in the temperature range of 350-480°C. Corrosion products were analyzed by SEM-SEI, BSE and EDS. It was found that the oxide layer on the WE43 alloy has a very good resistance to oxidation. The high protective properties of the layer should be attributed to the presence of yttrium in this alloy. On the other hand, a porous, two-layer scale with a low adhesion to the substrate forms on the ZRE1 alloy. The increase in the sample mass in dry gas is lower than that in humidified gas.
Widespread opinion holds that calcareous rocks have limited suitability for use in the production of aggregates and stone products having adequate frost resistance. However, some of the rocks, in particular those from earlier geological periods, provide a promising alternative to silicate rocks. The paper presents results of the analysis of Devonian carbonate rock originating from two selected mines in the Swietokrzyskie region. The examined mines extract limestone from two different deposits of the same age. The rock samples are collected from beds lying at different depths, distinct in texture and color in macroscopic examination. It was found that despite the changes in bulk density, porosity and absorption, all the examined samples were frost resistant. Using the Differential Analysis of Volumetric Strain method, the content of ice formed in the pore spaces was determined. In addition, the ratio of the content of water capable of freezing to the total pore volume, and the total amount of water absorbed due to capillary action in rock samples soaked in water, were analyzed. In all cases, it was revealed that the destructive action of freezing water was weakened due to a relatively low content of water capable of freezing and a substantial volume of pores that are not filled with water in capillary absorption. It is extremely important to be able to classify the available rock material. The generally adopted methods, including absorptivity tests, do not allow for precise categorization. In the investigations, the authors focused on the analysis of the basic factors that are decisive for rock durability, including bulk density, pore filling level and volume absorption. The authors do not correspond compressive strength and resistance to abrasion as this will be the subject of further research.
The aim of this study was to determine the effect of carfentrazone-ethyl (CE) doses of 0.265, 5.280, 10.560, 21.180, 42.240 μg kg-1 soil DM on fungi, Acnomycetes, organotrophic bacteria, total oligotrophic bacteria and spore-forming oligotrophic bacteria, and on the activity of dehydrogenases, catalase, urease, alkaline phosphatase, acid phosphatase, arylsulfatase and β-glucosidase. Carfentrazone-ethyl had a stimulating effect on total oligotrophic bacteria and organotrophic bacteria, but it inhibited the growth of Azotobacter, fungi, spore-forming oligotrophic bacteria and Actinomycetes. The analyzed substance modified the structure of soil microbial communities, and it induced the most profound changes in fungi. The highest values of the colony development (CD) index and the eco-physiological (EP) index were observed in organotrophic bacteria. The optimal dose of carfentrazone-ethyl stimulated the activity of dehydrogenases, catalase, urease, alkaline phosphatase, acid phosphatase and β-glucosidase, but it had no effect on arylsulfatase. The highest doses of the analyzed substance inhibited the activity of dehydrogenases (reduction from 11.835 to 11.381 μmol TPF), urease (reduction from 0.545 to 0.500 mmol N-NH4) and arylosulfatase (reduction from 0.210 to 0.168 mmol PNP). Dehydrogenases were most resistant to CE, whereas acid phosphatase and arylsulfatase were least resistant to the analyzed compound
A thermal resistance characterization of semiconductor quantum-well heterolasers in the AlGaInAs-AlGaAs system (λst ≈ 0.8 μm), GaSb-based laser diodes (λst ≈ 2 μm), and power GaN light-emitting diodes (visible spectral region) was performed. The characterization consists in investigations of transient electrical processes in the diode sources under heating by direct current. The time dependence of the heating temperature of the active region of a source ΔT(t), calculated from direct bias change, is analyzed using a thermal RTCT equivalent circuit (the Foster and Cauer models), where RT is the thermal resistance and CT is the heat capacity of the source elements and external heat sink. By the developed method, thermal resistances of internal elements of the heterolasers and light-emitting diodes are determined. The dominant contribution of a die attach layer to the internal thermal resistance of both heterolaser sources and light-emitting diodes is observed. Based on the performed thermal characterization, the dependence of the optical power efficiency on current for the laser diodes is determined.
The study was aimed at evaluating microbial contamination on the premises of the sewage treatment plant by determining the concentrations of selected groups of airborne microorganisms. Another objective was to determine the antibiotic sensitivity patterns of isolated strains of staphylococci. The research was conducted in a seasonal cycle, by the impaction method using Merck MAS-100 air sampler. Samples were collected at six sites, each representing a different stage of sewage treatment. The susceptibility of isolated staphylococci was assessed with the disc-diffusion method, following the recommendations of the EUCAST. The results indicate that the microbial population in the air of the investigated area was dominated by mold fungi, whose highest average concentration was recorded at site IV located near the final clarifier (7672 CFU•m-3). Heterotrophic bacteria and mannitol-positive staphylococci were the most numerous at locations where sewage undergoes primary treatment. In each subseuqent stage the number of microorganisms emitted into the air from the sewage was lower. Antibiograms show that more than 50% of Staphylococcus spp. exhibited resistance to penicillin and 20% to rifampicin. In addition, 90% of the analyzed strains were sensitive to other antibiotics. The fungal community included the following genera: Cladosporium, Fusarium, Alternaria, Penicillium, Aspergillus, Aureobasidium, and Acremonium.The highest air contamination with all studied groups of microorganisms was recorded at the locations where mechanical sewage treatment was performed. During the subsequent stages lower numbers of heterotrophic bacteria were emitted into the air. The air in the investigated sewage treatment plant did not contain multidrug-resistant staphylococci.
The paper presents the results of a numerical study devoted to the hydraulic properties of a network of parallel triangular microchannels (hydraulic diameter Dh = 110 um). Previous experimental investigations had revealed that pressure drop through the microchannels system dramatically increases for the Reynolds number exceeding value of 10. The disagreement of the experimental findings with the estimations of flow resistance based on the assumption of fully developed flow were suspected to result from the so-called scale effect. Numerical simulations were performed by using the classical system of flow equations (continuity and Navier-Stokes equations) in order to explain the observed discrepancies. The calculations showed a very good agreement with the experimental results proving that there is no scale effect for the microchannels considered, i.e. the relevance of the constitutive flow model applied was confirmed. It was also clearly indicated that the excessive pressure losses in the high Reynolds number range are due to the secondary flows and separations appearing in several regions of the microchannel system.
In the paper a new implementation of a compact smart resistive sensor based on a microcontroller with internal ADCs is proposed and analysed. The solution is based only on a (already existing in the system) microcontroller and a simple sensor interface circuit working as a voltage divider consisting of a reference resistor and a resistive sensor connected in parallel with an interference suppression capacitor. The measurement method is based on stimulation of the sensor interface circuit by a single square voltage pulse and on sampling the resulting voltage on the resistive sensor. The proposed solution is illustrated by a complete application of the compact smart resistive sensor used for temperature measurements, based on an 8-bit ATxmega32A4 microcontroller with a 12-bit ADC and a Pt100 resistive sensor. The results of experimental research confirm that the compact smart resistive sensor has 1°C resolution of temperature measurement for the whole range of changes of measured temperatures.
In the paper selected methods of measuring the thermal resistance of an IGBT (Insulated Gate Bipolar Transistor) are presented and the accuracy of these methods is analysed. The analysis of the measurement error is performed and operating conditions of the considered device, at which each measurement method assures the least measuring error, are pointed out. Theoretical considerations are illustrated with some results of measurements and calculations.
In this paper an attempt to determine the relationship between the electrical resistivity and the tensile strength and hardness of cast iron of carbon equivalent in the range from 3.93% to 4.48%. Tests were performed on the gray cast iron for 12 different melts with different chemical composition. From one melt poured 6 samples. Based on the study of mechanical and electro-resistive determined variation characteristics of tensile strength, hardness and resistivity as a function of the carbon equivalent. Then, regression equations were developed as power functions describing the relationship between the resistivity of castings and their tensile strength and hardness. It was found a high level of regression equations to measuring points, particularly with regard to the relationship Rm=f(ρ). The obtained preliminary results indicate the possibility of application of the method of the resistance to rapid diagnostic casts on the production line, when we are dealing with repeatable production, in this case non variable geometry of the product for which it has been determinated before a regression equation.
The paper presents the results of comparative tests of the fatigue properties conducted on two non-ferrous alloys designated as Al 6082 and Al 7075 which, due to the satisfactory functional characteristics, are widely used as engineering materials. The fatigue tests were carried out using a proprietary, modified low cycle test (MLCF). Particular attention was paid to the fatigue strength exponent b and fatigue ductility exponent c. Based on the tests carried out, the results comprised within the range defined by the literature were obtained. These results prove a satisfactory sensitivity of the method applied, its efficiency, the possibility of conducting tests in a fully economical way and above all the reliability of the obtained results of the measurements. Thus, the thesis has been justified that the modified low cycle fatigue test (MLCF) can be recommended as a tool used in the development of alloy characteristics within the range of low-cycle variable loads
Paper presents the results of evaluation of heat resistance and specific heat capacity of MAR-M-200, MAR-M-247 and Rene 80 nickel superalloys. Heat resistance was evaluated using cyclic method. Every cycle included heating in 1100°C for 23 hours and cooling for 1 hour in air. Microstructure of the scale was observed using electron microscope. Specific heat capacity was measured using DSC calorimeter. It was found that under conditions of cyclically changing temperature alloy MAR-M-247 exhibits highest heat resistance. Formed oxide scale is heterophasic mixture of alloying elements, under which an internal oxidation zone was present. MAR-M-200 alloy has higher specific heat capacity compared to MAR-M-247. For tested alloys in the temperature range from 550°C to 800°C precipitation processes (γ′, γ′′) are probably occurring, resulting in a sudden increase in the observed heat capacity.
This paper presents an experimental study on chicken egg white solution ultrafiltration, where membrane fouling has been the main point of concern. Separation process has been performed with a 150 kDa tubular ceramic TiO2/Al2O3 membrane. The operating parameters have been set as follows: transmembrane pressure 105–310 kPa, cross-flow velocity 2.73–4.55 m/s, pH 5 and constant temperature of 293 K. Resistance-in-series model has been used to calculate total resistance and its components. The experimental data have been described with four pore blocking models (complete blocking, intermediate blocking, standard blocking and cake filtration). The results obtained show that the dominant fouling mechanism is represented by cake filtration model.
Commercially pure titanium is less expensive, generally more corrosion resistant and lower in strength than its alloys, and is not heat-treatable. The use of Ti and its alloys as construction materials under severe friction and wear conditions is limited due to their poor tribological properties. Nevertheless, proper addition of hard ceramic particles into Ti and its alloys has proved to be an efficient way to enhance their mechanical and wear properties. Our purpose in this work was to analyze the corrosion, tribocorrosion, mechanical and morphological effects of combining titanium carbide with titanium metal, to create a unique composite via spark plasma sintering technique (SPS). Composites with different mass percentage (1, 5, 10, 15 and 20 wt %) of ceramic phase were produced. The samples of pure Ti and Ti-6Al-4V alloy were also tested, as a reference. These composites were examined for mechanical properties and corrosion resistance in an environment similar to the human body (Ringer’s solution). Open circuit potential (OPC) and anodic polarization measurements were performed. The properties of titanium composites reinforced with micro- and nanocrystalline TiC powders were compared. It was stated that wear properties were significantly improved with increasing amount of TiC in matrix, especially in the case of nanocrystalline reinforcement. In terms of corrosion resistance, the composites showed slightly worse properties compared to pure titanium and Ti-6Al-4V alloy.
The sintered stainless steels of different microstructures (austenitic, ferritic and duplex) were laser surface alloyed with hard powders (SiC, Si3N4) and elemental alloying powders (Cr, FeCr, FeNi) to obtain a complex steel microstructure of improved properties. Laser surface alloying (LSA) involved different strategies of powder placing: the direct powder feeding to the molten metal pool and filling grooves machined on the sample surface by powder, and then laser surface melting. Obtained microstructures were characterised and summarised, basing on LOM, SEM and XRD analysis. The links between base material properties, like superficial hardness and microhardness, derived microstructures and erosion resistance was described. The LSA conditions and alloying powder placement strategies on erosion resistance was evaluated. The erosion wear is lower for Cr, FeCr, FeNi laser alloying, where powders were dissolved in the steel microstructure, and hard phases were not precipitated. Precipitations of hard phases (carbides, silicides, martensite formation) reduce erosion resistance of SiC alloyed stainless steel. The LSA with Si3N4 works better due to lack of precipitates and formation of a soft and ductile austenitic microstructure. The erosion wear at the impingement angle of 90° is high for hard and therefore brittle surface layers obtained as a result of alloying by hard particles (SiC, Si3N4). The softer and ductile austenitic stainless steel resist better than harder ferritic and duplex stainless steel material at studied erodent im pingement angle.
Operating conditions turbocharger (high temperature and corrosive environment) mean that the device is classified into one of the most elements of the emergency drive unit of the car. The failure rate can be reduced through the use of modern heat-resistant materials, which include based alloys FeAl intermetallic phase. Intermetallic alloys belong to the group of materials known as prospective due to their advantageous properties, in particular their high specific strength, high melting point and good resistance to corrosion and oxidation at high temperatures. In the article presented results of the research axis roll control system variable geometry blades made of intermetallic alloy Fe40Al5Cr0,2TiB as a substitute so far made of austenitic steel. A verification service conditions, comparing the degradation of the material previously used by manufacturers of turbochargers for elements of the control system degradation axes made of intermetallic alloy Fe40Al5Cr0,2TiB. The study consisted of determining microstructure and corrosion products after use. Observations of the structure and the surface of the corrosion tests were performed using light microscopy, scanning electron microscopy and X-ray microanalysis EDS chemical composition.
This paper presents the results of the abrasive wear resistance of selected types of nodular cast iron, including ADI, cooperating with quartz sand and 100 grit abrasive paper. It has been shown that carbides in nodular cast iron cause an increase in wear resistance of 6 to 12% depending on the surface fraction of the carbides and type of the matrix. For the same unit pressure the mass loss of the cast iron cooperating with quartz sand is many times larger than the cast iron cooperating with abrasive paper. For both abrasives the highest wear resistance showed nodular cast iron with upper and lower bainite and carbides.
In this study, the mechanical tests were carried out on ductile iron of EN-GJS-600-3 grade and on grey cast iron of EN-GJL-250 grade. The fatigue life was evaluated in a modified low-cycle fatigue test (MLCF), which enables the determination of parameters resulting from the Manson-Coffin-Morrow relationship. The qualitative and quantitative metallographic studies conducted by light microscopy on selected samples of ductile iron with spheroidal graphite and grey cast iron with lamellar graphite (showing only small variations in mechanical properties,) confirmed also small variations in the geometrical parameters of graphite related with its content and morphological features.