The meat of goat kids and lambs as a possible source of Toxoplasma gondii for consumers

Toxoplasmosis is a worldwide zoonosis and the consumption of undercooked meat is a major risk factor for human infection. Antibodies to Toxoplasma gondii were found in 28.2% (11/39) and 27.8% (5/18) of home-slaughtered goat kids (n = 39) and lambs (n = 18) from four farms in the Czech Republic. The DNA of the parasite was detected in the tissues (diaphragm and/or lung) of 10.3% (4/39) of kids and 16.7% (3/18) of lambs. Although the consumption of kid and lamb meat is low in the Czech Republic, its consumption may become a source of Toxoplasma infection in humans

Influance of the machining to the microstructure properties of creep resistant nickel based superalloy

Strojní součásti vyráběné ze žáropevných niklových slitin určených pro vysokoteplotní aplikace musí již z principu aplikace odolávat náročným pracovním podmínkám. Volba technologie výroby dílů má výrazný vliv na výsledné funkční vlastnosti a měla by být nezanedbatelnou součástí správného návrhu součásti. Třískové obrábění je stále nutnou součásti výroby tvarově složitých dílů s vysokou tvarovou a rozměrovou přesností. Dokončovací operace obrábění se mohou podepsat na životnosti dílů. Nevhodnou technologií může dojít ke snížení únavových mezí, ze kterých návrh vychází. Obrábění může mít vliv na změnu povrchové vrstvy například změnou tvrdosti, vznikem napětí nebo změnou chemického složení, přechodem prvků mezi obrobkem a nástrojem. Cílem článku je popis mikrostrukturních změn v důsledku třískového obrábění a následné ovlivnění niklové slitiny pro mechanické zkoušky či přímou aplikaci do provozu.SGS19/162/OHK2/3T/12Machine parts made of creep-resistant nickel alloys designed for high-temperature applications must, by virtue of their application principle, withstand demanding working conditions. The choice of component manufacturing technology has a significant effect on the resulting functional properties and should be a significant part of the correct design of the part. Machining is still a necessary part of the production of complex shaped parts with high dimensional accuracy. Finishing operations can affect the life of parts. Improper technology can reduce the fatigue limits on which the design is based. Machining can cause the change of the surface layer, for example by changing the hardness, induce stress or changing the chemical composition, the transition of elements between the workpiece and the tool. The aim of the paper is to describe microstructural changes due to machining and subsequent influence of nickel alloy for mechanical tests or direct application into operation

Phase Composition of Silica Fume-Portland Cement Systems Formed under Hydrothermal Curing Evaluated by FTIR, XRD, and TGA

Two substitution levels of Portland cement by silica fume (SF; 30 and 50 mass%) and three hydrothermal treatment regimes (0.5, 1.2, and 2 MPa and 165, 195, and 220 degrees C for 7 days, respectively) were selected for the investigation of high-temperature phase formation. A combination of thermogravimetric, X-ray diffraction, and Fourier transform infrared analyses in the mid-IR region was used to overcome the shortcomings of individual techniques for the identification of these complex systems. Changes in molecular water amounts, the polymerization degree of silicate chains, or their decomposition due to transformations and crystallization of phases at hydrothermal conditions were observed and discussed concerning composition. Contrary to the calciochondrite, hydrogrossular phases, alpha-C2SH, and jaffeite detected in the systems without SF, a decrease in CaO/SiO2 ratio resulted in the formation of stable tobermorite in the case of 30 mass% SF, whilst calcium hydrogen silicate, gyrolite, and cowlesite were identified as more thermally stable phases in the samples with 50 mass% SF

Experimental investigation of suitable cutting conditions of dry drilling into high-strength structural steel

Dry machining is one of the main ways to reduce the environmental burden of the machining process and reduce the negative effect of the cutting fluid and aerosols on operators. In addition, dry machining can reduce overall machining costs and, in the case of large workpieces, reduce the extra work associated with removing residual cutting fluid from the workpiece and adjacent area. For high-strength structural steel products, it is typical to drill holes with larger diameters of around 20 mm. Therefore, this work is devoted to the investigation of the dry drilling process carried out on a workpiece made of S960QL steel with a helical drill with a diameter of 21 mm. The aim was to find suitable cutting conditions for dry drilling with regard to process stability and workpiece quality. An experiment performed with a coolant served as a comparison base. A dry drilling experiment was performed with cutting speeds from 30 to 70 m center dot min(-1) and feeds from 0.1 to 0.3 mm center dot rev(-1), and with the results of this experiment, the same experiment with flood cooling was performed. During the drilling process, spindle torque values were recorded using the indirect spindle current recording method. The macroscopic chip morphology was studied to understand the cutting process. The chip thickness ratio was measured, as well as the maximum diameter of spiral chips. On the final workpiece, the qualitative and dimensional parameters of the holes were evaluated, such as the diameter, cylindricity and surface roughness, depending on the change in the cutting conditions and cutting environment. Evaluation of the obtained data led to the following conclusions. When drilling the S960QL material, there is only a very small increase in the drilling torque during dry drilling compared to drilling with cutting fluid. The increase in friction demonstrated by the chip thickness coefficient is significant. The influence of the environment on the dimensional accuracy showed a tendency for a slight increase in the holes' diameters during dry machining. In comparison, the cylindricity of the dry-drilled holes shows a lower deviation than the holes drilled with cutting fluid. The surface roughness of the holes after dry drilling is affected by the increased friction of the outgoing chips, despite the resulting parameters being very good due to the drilling technology standards. This work provides a comprehensive view of the dry drilling process under defined conditions, and the results represent suitable cutting conditions to achieve a stable cutting process and a suitable quality of drilled holes.Web of Science1416art. no. 438

Novel drill geometries for dry drilling of stainless steel

One completely new geometry and two modified chip breaker geometries were designed to increase the stability and reliability of the stainless steel dry drilling process. Experiments were performed and the results of individual tools were compared with a conventional solid carbide twist drill Gühring Ratio with a diameter of 5 mm. A matrix of three feed rates (0,03–0,07 mm/rev) and three cutting speeds (20–30 m/min) was designed for the cutting conditions. Precipitation-hardenable stainless steel 17-4 PH was chosen as a workpiece. During the experiment, the values of thrust force, spindle torque, temperature of the tool, surface roughness, chips morphology and chips division were recorded and compared with the reference tool. The results showed that compared to the reference tool A, the tool C - a multipoint drill with grooves through the cutting edge achieve approximately 4 % lower values of thrust force and 10–15 % lower values of spindle torque. Tool D with a step drill geometry achieve approximately 17 % lower values of thrust force and 10–15 % lower values of spindle torque and there is no chip clogging in the flute with C and D geometries. This effect is confirmed by the fact the spindle torque basically does not increase with the increasing depth of drilling. Tool B – new designed geometry achieve approximately 15 % lower values of thrust force and similar spindle torque values as the reference drill A. Tool temperature is a very important factor when dry drilling. Compared to the reference drill A, it was possible to achieve the tool temperature reduction of 20 % with the new geometry B, as well as with the multipoint drill C reduction by 26 % and with the step drill D reduction approximately by 30 %. All the modified drills also achieved a reduction in the surface roughness of the drilled holes. By 17 %, 35 % and 48 % lower surface roughness Ra was achieved with drills B, C and D. Chip morphology was significantly different for the tested drills. Conventional twist drills A and B generated helical short chips. While C and D twist drills with divided cutting edges generated ribbon snarled chips. Thanks to the reduction of cutting forces and temperature, it is possible to stably operate the drilling process with a higher cutting speed and feed rate, which leads to an increase in the efficiency and reliability of the machining process.Web of Science9252050

Influance of the machining to the microstructure properties of creep resistant nickel based superalloy

Strojní součásti vyráběné ze žáropevných niklových slitin určených pro vysokoteplotní aplikace musí již z principu aplikace odolávat náročným pracovním podmínkám. Volba technologie výroby dílů má výrazný vliv na výsledné funkční vlastnosti a měla by být nezanedbatelnou součástí správného návrhu součásti. Třískové obrábění je stále nutnou součásti výroby tvarově složitých dílů s vysokou tvarovou a rozměrovou přesností. Dokončovací operace obrábění se mohou podepsat na životnosti dílů. Nevhodnou technologií může dojít ke snížení únavových mezí, ze kterých návrh vychází. Obrábění může mít vliv na změnu povrchové vrstvy například změnou tvrdosti, vznikem napětí nebo změnou chemického složení, přechodem prvků mezi obrobkem a nástrojem. Cílem článku je popis mikrostrukturních změn v důsledku třískového obrábění a následné ovlivnění niklové slitiny pro mechanické zkoušky či přímou aplikaci do provozu.SGS19/162/OHK2/3T/12Machine parts made of creep-resistant nickel alloys designed for high-temperature applications must, by virtue of their application principle, withstand demanding working conditions. The choice of component manufacturing technology has a significant effect on the resulting functional properties and should be a significant part of the correct design of the part. Machining is still a necessary part of the production of complex shaped parts with high dimensional accuracy. Finishing operations can affect the life of parts. Improper technology can reduce the fatigue limits on which the design is based. Machining can cause the change of the surface layer, for example by changing the hardness, induce stress or changing the chemical composition, the transition of elements between the workpiece and the tool. The aim of the paper is to describe microstructural changes due to machining and subsequent influence of nickel alloy for mechanical tests or direct application into operation

Synthesis of Mg-Al Hydrotalcite Clay with High Adsorption Capacity

A novel Mg-Al metal oxide has been successfully synthesized by the calcination of hierarchical porous Mg-Al hydrotalcite clay obtained by using filter paper as a template under hydrothermal conditions. Various characterizations of the obtained nanoscale oxide particles verified the uniform dispersion of Mg-Al metal oxides on the filter paper fiber, which had a size of 2–20 nm and a highest specific surface area (SSA) of 178.84 m2/g. Structural characterization revealed that the as-prepared Mg-Al metal oxides preserved the tubular morphology of the filter paper fibers. Further experiments showed that the as-synthesized Mg-Al metal oxides, present at concentrations of 0.3 g/L, could efficiently remove sulfonated lignite from oilfield wastewater (initial concentration of 200 mg/L) in a neutral environment (pH = 7) at a temperature of 298 K. An investigation of the reaction kinetics found that the adsorption process of sulfonated lignite (SL) on biomorphic Mg-Al metal oxides fits a Langmuir adsorption model and pseudo-second-order rate equation. Thermodynamic calculations propose that the adsorption of sulfonated lignite was spontaneous, endothermic, and a thermodynamically feasible process

The Inhibition Property and Mechanism of a Novel Low Molecular Weight Zwitterionic Copolymer for Improving Wellbore Stability

In this work, a novel low molecular weight zwitterionic copolymer for improving wellbore stability, which is expected to be an alternative to the current shale inhibitors, was obtained by copolymerization of tris hydroxyethyl allyl ammonium bromide (THAAB), 2-acrylamido-2- methyl propane sulfonic acid (AMPS) and acrylamide (AM), initiated by a redox initiation system in an aqueous solution. The copolymer, denoted as SX-1, was characterized by FT-IR, TGA-DSC, and GPC. Results demonstrated that the molecular weight of SX-1 was approximately 13,683 g/mol and it displayed temperature resistance up to 225 °C. Regarding the inhibition performance, evaluation experiments showed the hot rolling recovery of a Longmaxi shale sample in 2.0 wt % SX-1 solutions was up to 90.31% after hot rolling for 16 h at 120 °C. The Linear swelling height of Na-MMT artificial core in 2.0 wt % SX-1 solution was just 4.74 mm after 16 h. Methods including particle size analysis, FTIR, XRD, and SEM were utilized to study the inhibition mechanism of SX-1; results demonstrated that SX-1 had entered into the inner layer of sodium montmorillonite (Na-MMT) and adsorbed on the inner surface, and the micro-structure of Na-MMT was successfully changed by SX-1. The particle size of Na-MMT in distilled water was 8.05 μm, and it was observed that its size had increased to 603 μm after the addition of 2.0 wt % of SX-1. Its superior properties make this novel low molecular weight copolymer promising for ensuring wellbore stability, particularly for high temperature wells

Microbial quality and molecular identification of cultivable microorganisms isolated from an urban drinking water distribution system (Limassol, Cyprus)

Microorganisms can survive and multiply in aged urban drinking water distribution systems, leading to potential health risks. The objective of this work was to investigate the microbial quality of tap water and molecularly identify its predominant cultivable microorganisms. Tap water samples collected from 24 different households scattered in the urban area of Limassol, Cyprus, were microbiologically tested following standard protocols for coliforms, E. coli, Pseudomonas spp., Enterococcus spp., and total viable count at 22 and 37 °C. Molecular identification was performed on isolated predominant single colonies using 16SrRNA sequencing. Approximately 85 % of the household water samples were contaminated with one or more microorganisms belonging to the genera of Pseudomonas, Corynebacterium, Agrobacterium, Staphylococcus, Bacillus, Delftia, Acinetobacter, Enterococcus, Enterobacter, and Aeromonas. However, all samples tested were free from E. coli. This is the first report in Cyprus molecularly confirming specific genera of relevant microbial communities in tap water

Acetylation Modification of Waste Polystyrene and Its Use as a Crude Oil Flow Improver

Polystyrene is used in a wide range of applications in our lives, from machine housings to plastic cups and miniature electronic devices. When polystyrene is used, a large amount of waste is produced, which can cause pollution to the environment and even harm biological and human health. Due to its low bulk density (especially the foamed type) and low residual value, polystyrene cannot be easily recycled. Often waste polystyrene is difficult to recycle. In this paper, waste polystyrene has been modified by using acetic anhydride which caused a crude oil flow improver. The results showed that modified polystyrene improves the flow properties of the crude oil, reducing the viscosity and the pour point of the crude oil by up to 84.6% and 8.8 °C, respectively. Based on the study of the paraffin crystal morphology, the mechanism of improving the flow capacity of crude oil by modified polystyrene was proposed and analyzed