Publications by authors named "Kolar V"

Article Synopsis
  • - This research investigates the mechanical and thermo-mechanical properties of recycled low-density polyethylene (LDPE) sourced from post-consumer waste, focusing on static and cyclic fatigue testing.
  • - The results revealed that the recycled LDPE performed comparably to virgin materials in both static and cyclic tests, with no significant loss in tensile strength and an enhancement in mechanical performance due to the high-quality regranulates produced.
  • - Advanced techniques like Fourier Transform Infrared Spectroscopy (FTIR) and Differential Scanning Calorimetry (DSC) confirmed minimal changes in the material's chemical structure and thermal properties between recycled and virgin LDPE.
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Article Synopsis
  • Wastewater effluents and rising water temperatures from climate change threaten freshwater ecosystems and biodiversity, prompting our study on their combined effects on aquatic communities.
  • We conducted a 21-day experiment with various treatments on a simplified freshwater food web, examining impacts on species survival, genetic diversity, and metabolic responses among benthic macroinvertebrates.
  • Results showed species-specific sensitivities, particularly in caddisflies and mayflies, where multi-stressor conditions led to reduced lipid content and phylogenetic diversity, indicating the need for molecular indicators to assess immediate ecological impacts.
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This work investigates the effect of varying the knitting structure and stitch length (SL) on various thermo-physiological and ergonomic comfort properties of the occupational graduated compression socks. Thermo-physiological comfort, ergonomic comfort and dimensional stability of theses stockings were analysed in a comparative manner. Obtained results were evaluated statistically using the technique of analysis of variance (ANOVA).

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Limited efficiency, lower durability, moisture absorbance, and pest/fungal/bacterial interaction/growth are the major issues relating to porous nonwovens used for acoustic and thermal insulation in buildings. This research investigated porous nonwoven textiles composed of recycled cotton waste (CW) fibers, with a specific emphasis on the above-mentioned problems using the treatment of silicon coating and formation of nanofibers via facile-solution processing. The findings revealed that the use of an economic and eco-friendly superhydrophobic (contact angle higher than 150°) modification of porous nonwovens with silicon nanofibers significantly enhanced their intrinsic characteristics.

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Multiple anthropogenic stressors influence the functioning of lakes and ponds, but their combined effects are often little understood. We conducted two mesocosm experiments to evaluate the effects of warming (+4 °C above ambient temperature) and environmentally relevant concentrations of a mixture of commonly used pharmaceuticals (cardiovascular, psychoactive, antihistamines, antibiotics) on tri-trophic food webs representative of communities in ponds and other small standing waters. Communities were constituted of phyto- and zooplankton and macroinvertebrates (molluscs and insects) including benthic detritivores, grazers, omnivorous scrapers, omnivorous piercers, water column predators, benthic predators, and phytophilous predators.

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This paper investigates the development of fabric materials using several blends of inherently fire-resistant (FR) fibers and various knitted structures. The samples are evaluated with respect to their performance and comfort-related properties. Inherently fire-resistant fibers, e.

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Compression stockings/socks are one of the most essential materials to treat vascular disorders in veins. However, the comfort of wearing such stockings over prolonged period of time is a major problem. There is limited research in the area of comfort optimization while retaining the compressional performance.

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Elevated environmental levels of elements originating from anthropogenic activities threaten natural communities and public health, as these elements can persist and bioaccumulate in the environment. However, their environmental risks and bioaccumulation patterns are often habitat-, species- and element-specific. We studied the bioaccumulation patterns of 11 elements in seven freshwater taxa in post-mining habitats in the Czech Republic, ranging from less polluted mining ponds to highly polluted fly ash lagoons.

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The paper deals with research focused on the use of fillers in the field of polymeric materials produced by additive technology SLA (stereolithography). The aim of the research is to evaluate 3D printing parameters, the mechanical properties (tensile strength, hardness), and the interaction of individual phases (polymer matrix and filler) in composite materials using SEM analysis. The tested fillers were cotton flakes and ground carbon fibres in different proportions.

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The current work is focused on numerical and experimental studies of woven fabric composites modified by hybridisation with biological (cellulosic) filler materials. The mechanical performance of the composites is characterized under tensile, bending and impact loads and the effect of hybridisation is observed with respect to pure and nonhybrid composites. Numerical models are developed using computational tools to predict mechanical performance under tensile loading.

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Deposits of fly ash and other coal combustion wastes are common remnants of the energy industry. Despite their environmental risks from heavy metals and trace elements, they have been revealed as refuges for threatened terrestrial biodiversity. Surprisingly, freshwater biodiversity of fly ash sedimentation lagoons remains unknown despite such lack of knowledge strongly limits the efficient restoration of fly ash deposits.

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Neonicotinoids are increasingly and widely used systemic insecticides in agriculture, residential applications, and elsewhere. These pesticides can sometimes occur in small water bodies in exceptionally high concentrations, leading to downstream non-target aquatic toxicity. Although insects appear to be the most sensitive group to neonicotinoids, other aquatic invertebrates may also be affected.

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For a sustainable environment and to tackle the pollution problem, industrial wastes can be used in concrete composite materials. This is especially beneficial in places prone to earth quack and lower temperature. In this study, five different types of waste fibres such as polyester waste, rubber waste, rock wool waste, glass fibre waste and coconut fibre waste were used as an additive in 0.

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Background: The mayfly Ephemera (Sinephemera) glaucops Pictet, 1843 has been considered regionally extinct in the Czech Republic, with the last occurrence dating from 1933. Its extinction was connected with the anthropogenic changes of lowland rivers, forming the original habitat of within the area of the Czech Republic. However, the species has been reported as spreading in man-made, often post-industrial waterbodies in Germany, The Netherlands and Austria since the 1970s.

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The aim of this research was to evaluate the effect of untreated and 5% aqueous NaOH solution-treated filler of the plant Jatropha Curcas L. on the mechanical properties of adhesive bonds, especially in terms of their service life at different amplitudes of cyclic loading. As a result of the presence of phorbol ester, which is toxic, Jatropha oilseed cake cannot be used as livestock feed.

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This paper deals with developing and implementing a bidirectional galvanically isolated on-board charger of a high-power density. The power density of the new charger was 4 kW/kg and 2.46 kW/dm, and the maximum efficiency was 96.

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This research is aimed at evaluating the effect of low-cycle fatigue on a newly designed hybrid sandwich ski structure to determine the changes that may occur due to cyclic loading and thus affect its use. This is primarily concerned with the fatigue behavior of the tested ski over different time intervals simulating its seasonal use and its effect on the mechanical properties of the ski, i.e.

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This paper focuses on the comfort properties of graduated and preventive compression stockings for people who work long hours in standing postures and for athletes for proper blood circulation. The present study was conducted in order to investigate the effects of the yarn insertion density and inlaid stitches on the performance of the compression stockings. The effects of these parameters on the thermo-physiological comfort properties were tested with standard and developed methods of testing.

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Additive production is currently perceived as an advanced technology, where intensive research is carried out in two basic directions-modifications of existing printing materials and the evaluation of mechanical properties depending on individual production parameters and the technology used. The current research is focused on the evaluation of the fatigue behavior of 3D-printed test specimens made of pure PLA and PLA reinforced with filler based on pinewood, bamboo, and cork using FDM (fused deposition modeling) technology. This research was carried out in response to the growing demand for filaments from biodegradable materials.

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The research is focused on the evaluation of mechanical properties of adhesive bonds with a composite layer of adhesive to increase their service life (safety) under cyclic loading of different intensities. Cyclic loading represents a frequent cause of adhesive bond failure and, thus, a reduction in their service life. Waste from the production of coconut oil, that is, coconut shells in the form of particles, was used as a filler.

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The article focuses on the machining of polymeric materials polypropylene (PP) and un-plasticized poly vinyl chloride (PVC-U) after surface treatment with polyurethane and acrylate coatings using waterjet technology. Two types of waterjet technologies, abrasive waterjet (AWJ) and waterjet without abrasive (WJ), were used. The kerf width and its taper angle, at the inlet and outlet of the waterjet from the workpiece, were evaluated.

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The research is focused on the design and development of woven textile-based structural hollow composites. E-Glass and high tenacity polyester multifilament yarns were used to produce various woven constructions. Yarn produced from cotton shoddy (fibers extracted from waste textiles) was used to develop hybrid preforms.

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This study is focused on the mechanical properties and service life (safety) evaluation of hybrid adhesive bonds with shaped overlapping geometry (wavy-lap) and 100% natural cotton fabric used as reinforcement under cyclic loading using various intensities. Cyclic loading were implemented between 5-50% (267-2674 N) and 5-70% (267-3743 N) from the maximum strength (5347 N) measured by static tensile test. The adhesive bonds were loaded by 1000 cycles.

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Continuous monitoring of the intracranial pressure (ICP) is essential in neurocritical care. There are a variety of ICP monitoring systems currently available, with the intraventricular fluid filled catheter transducer currently representing the "gold standard". As the placement of catheters is associated with the attendant risk of infection, hematoma formation, and seizures, there is a need for a reliable, non-invasive alternative.

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