Pupils’ risk behavior in the lower secondary school

Bullying and violence at school belong to the risk behavior and represent a topic often discussed in scientific community. For some research workers this topic is populist, however in practice it is serious and still relevant, because a big part of the teachers is still vulnerable against bullying and, if it occurs, they cannot deal with its in due time and properly way. This paper focuses on selected factors closely related to bullying such as the form and frequency of bullying that are put into context with other variables

Biotransformation of benzonitrile herbicides via the nitrile hydratase–amidase pathway in rhodococci

Abstract The aim of this work was to determine the ability of rhodococci to transform 3,5-dichloro-4-hydroxybenzonitrile (chloroxynil), 3,5-dibromo-4-hydroxybenzonitrile (bromoxynil), 3,5-diiodo-4-hydroxybenzonitrile (ioxynil) and 2,6-dichlorobenzonitrile (dichlobenil); to identify the products and determine their acute toxicities. Rhodococcus erythropolis A4 and Rhodococcus rhodochrous PA-34 converted benzonitrile herbicides into amides, but only the former strain was able to hydrolyze 2,6-dichlorobenzamide into 2,6-dichlorobenzoic acid, and produced also more of the carboxylic acids from the other herbicides compared to strain PA-34. Transformation of nitriles into amides decreased acute toxicities for chloroxynil and dichlobenil, but increased them for bromoxynil and ioxynil. The amides inhibited root growth in Lactuca sativa less than the nitriles but more than the acids. The conversion of the nitrile group may be the first step in the mineralization of benzonitrile herbicides but cannot be itself considered to be a detoxification

Cross-linked gelatine by modified dextran as a potential bioink prepared by a simple and non-toxic process

Essential features of well-designed materials intended for 3D bioprinting via microextrusion are the appropriate rheological behavior and cell-friendly environment. Despite the rapid development, few materials are utilizable as bioinks. The aim of our work was to design a novel cytocompatible material facilitating extrusion-based 3D printing while maintaining a relatively simple and straightforward preparation process without the need for harsh chemicals or radiation. Specifically, hydrogels were prepared from gelatines coming from three sources-bovine, rabbit, and chicken-cross-linked by dextran polyaldehyde. The influence of dextran concentration on the properties of hydrogels was studied. Rheological measurements not only confirmed the strong shear-thinning behavior of prepared inks but were also used for capturing cross-linking reaction kinetics and demonstrated quick achievement of gelation point (in most cases < 3 min). Their viscoelastic properties allowed satisfactory extrusion, forming a self-supported multi-layered uniformly porous structure. All gelatin-based hydrogels were non-cytototoxic. Homogeneous cells distribution within the printed scaffold was confirmed by fluorescence confocal microscopy. In addition, no disruption of cells structure was observed. The results demonstrate the great potential of the presented hydrogels for applications related to 3D bioprinting.RP/CPS/2022/001; CZ.02.2.69/0.0/0.0/19_073/0016941; Ministerstvo Školství, Mládeže a Tělovýchovy, MŠMT: CZ.1.05/2.1.00/19.0376, RP/CPS/2022/003; Grantová Agentura České Republiky, GA ČR: 20-28732SMinistry of Education, Youth and Sports of the Czech republic-DKRVO [RP/CPS/2022/003, RP/CPS/2022/001]; project OP RDE Junior Grants of TBU in Zlin [CZ.02.2.69/0.0/0.0/19_073/0016941]; CEBIA-Tech Instrumentation [CZ.1.05/2.1.00/19.0376]; Czech Science FoundationGrant Agency of the Czech Republic [20-28732S

Method for in situ polypyrrole coating, and the example of its use for functionalization of polyurethane anisotropic electrospun mats

The in situ coating of polymer substrate with polypyrrole, described herein with detailed know-how, represents a novel technique of surface functionalization. The choice of oxidizing agent and the polymerization time both affect the properties of the thin polypyrrole layer. The specific conductivity, free surface energy, thickness, topography, and FTIR spectra of polypyrrole layer were determined. The conductive coatings were further used to functionalize both isotropic and anisotropic electrospun polyurethane nanofibrous mats to show their applicability and study the bioactive effect of both the anisotropy and conductivity together. The morphology of composites was studied by means of atomic force microscopy and scanning electron microscopy. A complex cytocompatibility study was performed, including determining cytotoxicity by optical and fluorescence microscopy, the advanced qualification of cell morphology by cell-image analysis, and a study of stem cell behavior. The results clearly showed the significant impact of substrate modification on cells, especially on fibroblasts while the embryonic stem cells were less affected. This study shows not only the effective way to prepare a thin conducting layer based on polypyrrole but also demonstrates its importance for the fabrication of smart biomaterials

Genotoxic mechanisms for the carcinogenicity of the environmental pollutants and carcinogens o-anisidine and 2-nitroanisole follow from adducts generated by their metabolite N-(2-methoxyphenyl)-hydroxylamine with deoxyguanosine in DNA

An aromatic amine, o-anisidine (2-methoxyaniline) and its oxidative counterpart, 2-nitroanisole (2-methoxynitrobenzene), are the industrial and environmental pollutants causing tumors of the urinary bladder in rats and mice. Both carcinogens are activated to the same proximate carcinogenic metabolite, N-(2-methoxyphenyl)hydroxylamine, which spontaneously decomposes to nitrenium and/or carbenium ions responsible for formation of deoxyguanosine adducts in DNA in vitro and in vivo. In other words, generation of N-(2-methoxyphenyl)hydroxylamine is responsible for the genotoxic mechanisms of the o-anisidine and 2-nitroanisole carcinogenicity. Analogous enzymes of human and rat livers are capable of activating these carcinogens. Namely, human and rat cytochorme P4502E1 is the major enzyme oxidizing o-anisidine to N-(2-methoxyphenyl)hydroxylamine, while xanthine oxidase of both species reduces 2-nitroanisole to this metabolite. Likewise, O-demethylation of 2-nitroanisole, which is the detoxication pathway of its metabolism, is also catalyzed by the same human and rat enzyme, cytochorme P450 2E1. The results demonstrate that the rat is a suitable animal model mimicking the fate of both carcinogens in humans and suggest that both compounds are potential carcinogens also for humans

Multiple pleistocene refugia and post-glacial colonization in the European chub (Squalius cephalus) revealed by combined use of nuclear and mitochondrial markers

To analyse patterns of nuclear and mitochondrial genetic variation in the European chub, Squalius cephalus (Linnaeus, 1758), in order to understand the evolutionary history of this species and to test biogeographical hypotheses for the existence of co-distributed European freshwater fish specie

Powder injection molded ceramic scaffolds: The role of pores size and surface functionalization on the cytocompatibility

The alumina-based scaffolds prepared by powder injection molding can be preferentially used for preparation of bone grafts. Here, the final architecture of alumina scaffolds was efficiently controlled by powder space holder size and volume ratio. The alumina is not intrinsically cell-instructive material and thus the coating with electrically-conducting polyaniline or polyaniline/biopolymer films prepared in a colloidal dispersion mode was used to provide this advanced property. The component of the extracellular matrix, sodium hyaluronate, or natural biopolymers (sodium alginate or chitosan) were employed, and, subsequently, the cytocompatibility of the native and functionalized alumina scaffolds were determined. Both the absence of cytotoxicity and the cytocompatibility that were revealed demonstrate the application potential of these composites. The scaffolds with pore size greater than 250 µm were more cytocompatibility than those with pores size between 125 and 250 µm. The cytocompatibility was confirmed under in vivo-mimicking dynamic cultivation conditions which further improve the cell distribution and growth. © 2022 The AuthorsRP/CPS/2022/001, RP/CPS/2022/003; CZ.02.2.69/0.0/0.0/19_073/0016941, JUNG-2020-001; Ministerstvo Školství, Mládeže a Tělovýchovy, MŠMT; Grantová Agentura České Republiky, GA ČR: 20-28732Sproject OP RDE Junior Grants of TBU in Zlin [20-28732S]; Czech Science Foundation [RP/CPS/2022/001]; Ministry of Education, Youth and Sports of the Czech Republic [RP/CPS/2022/003]; [CZ.02.2.69/0.0/0.0/19_073/001694 1

Powder injection molded ceramic scaffolds: The role of pores size and surface functionalization on the cytocompatibility

The alumina-based scaffolds prepared by powder injection molding can be preferentially used for preparation of bone grafts. Here, the final architecture of alumina scaffolds was efficiently controlled by powder space holder size and volume ratio. The alumina is not intrinsically cell-instructive material and thus the coating with electrically-conducting polyaniline or polyaniline/biopolymer films prepared in a colloidal dispersion mode was used to provide this advanced property. The component of the extracellular matrix, sodium hyaluronate, or natural biopolymers (sodium alginate or chitosan) were employed, and, subsequently, the cytocompatibility of the native and functionalized alumina scaffolds were determined. Both the absence of cytotoxicity and the cytocompatibility that were revealed demonstrate the application potential of these composites. The scaffolds with pore size greater than 250 µm were more cytocompatibility than those with pores size between 125 and 250 µm. The cytocompatibility was confirmed under in vivo-mimicking dynamic cultivation conditions which further improve the cell distribution and growth

Cross-Linked Gelatine by Modified Dextran as a Potential Bioink Prepared by a Simple and Non-Toxic Process

Essential features of well-designed materials intended for 3D bioprinting via microextrusion are the appropriate rheological behavior and cell-friendly environment. Despite the rapid development, few materials are utilizable as bioinks. The aim of our work was to design a novel cytocompatible material facilitating extrusion-based 3D printing while maintaining a relatively simple and straightforward preparation process without the need for harsh chemicals or radiation. Specifically, hydrogels were prepared from gelatines coming from three sources&mdash;bovine, rabbit, and chicken&mdash;cross-linked by dextran polyaldehyde. The influence of dextran concentration on the properties of hydrogels was studied. Rheological measurements not only confirmed the strong shear-thinning behavior of prepared inks but were also used for capturing cross-linking reaction kinetics and demonstrated quick achievement of gelation point (in most cases &lt; 3 min). Their viscoelastic properties allowed satisfactory extrusion, forming a self-supported multi-layered uniformly porous structure. All gelatin-based hydrogels were non-cytototoxic. Homogeneous cells distribution within the printed scaffold was confirmed by fluorescence confocal microscopy. In addition, no disruption of cells structure was observed. The results demonstrate the great potential of the presented hydrogels for applications related to 3D bioprinting