Polymer-zirconia based ceramic composites produced by 3D-printing

(English) Zirconia ceramic is widely used in numerous fields, such as electronics, machinery, and biomedical applications, due to its excellent properties as chemical resistance, thermal stability, electrical resistance, toughness, hardness, but also inertness and g biocompatibility. The 3D-printing technology has opened new doors for possible applications of zirconia and also allows for higher complexity of the shapes and structures, even for specimens with designed porosity, which would be until now unimaginable with traditional manufacturing methods like gel casting or cold isostatic pressing. The biocompatibility, inertness, and excellent aesthetic aspects of this ceramic make it also a preferred material for biomedical applications, more specifically in dentistry. However, application in the biomedical field has had some shortcomings, where the high hardness and brittleness of the material could cause discomfort or excessive wear. One of the aims of this thesis was to develop a new hybrid material that would complement the above-mentioned properties of zirconia and at the same time try to mimic the mechanical properties and biocompatibility of natural teeth using a combination of zirconia and acrylate polymer materials, while using additive manufacturing. The first part was focused on the development and manufacturing of such material. The idea of polymer-infiltrated ceramic networks (PICN), where a porous sintered ceramic structure is interpenetrated with a polymer matrix, was followed. The innovation of this technology was based on the 3D-printing of ceramic zirconia (3Y-TZP) scaffolds with designed porosity. After the optimization of the printing process, the 50% zirconia infill was chosen as the most appropriate porosity of the scaffold that was subsequently infiltrated with bisphenol A glycerolate dimethacrylate (Bis-GMA) and triethylene glycol dimethacrylate (TEGDMA) copolymer. After the successful manufacturing of 3D-printed PICN and the proper infiltration of the copolymer, the physical-chemistry properties of the new material were characterized, as well as its mechanical properties. The bacterial adhesion was evaluated against Gram-negative Escherichia coli and Gram-positive Streptococcus salivarius bacteria lines, revealing, that although such samples do not have antimicrobial properties, they do not promote excessive bacterial growth either. Regarding biocompatibility, the cell assay using human osteoblasts (MG-63) was carried out showing good cell viability. To improve the antimicrobial properties of manufactured PICN, the surface was modified with the adhesion of silver nanoparticles, which were embedded in an enzymatically modified phenolated lignin matrix (Ag@PL NPs), obtained from renewable resources, to avoid metal particle oxidation. The functionalization of the surface of the hybrid material with such Ag NPs allowed the reduction of bacterial growth by 90% on the modified surface. The last part of this thesis focused on the improvement of osseointegration of zirconia surface in vitro. Although it is an inert material, surface modification is required to avoid possible failures of zirconia once implanted in vivo. A polydopamine methacrylate copolymer, which has proved antibiofilm formation properties, was applied to the surface of zirconia. Characterization of the surfaces has proven good viability of the MG-63 cell line and also a great adhesion of the polymeric nanofilm, produced by cold plasma to the surface of zirconia discs. Overall, this thesis describes the 3D printing of PICN structures, which have a macroporous structure for the correct infiltration of the copolymer. The synergy and good adhesion between these materials have given rise to a prototype whose mechanical properties simulate those for natural teeth(Español)La zirconia es un material ampliamente utilizado en electrónica y en la biomedicina debido a su estabilidad química, estabilidad térmica, resistencia eléctrica, dureza, alta tenacidad, y biocompatibilidad debido a su naturaleza inerte. Con el desarrollo de la tecnología de fabricación aditiva (o 3D-printing), se han propuesto nuevas aplicaciones para la zirconia hasta ahora inimagibles empleando métodos de producción convencionales. Con la fabricación 3D se consiguen estructuras más complejas, con geometrías más variables y con un mayor control de la de porosidad. Estas características convierten esta cerámica en uno de los materiales predilectos para aplicaciones biomédicas, especialmente en la odontología. No obstante, la dureza y fragilidad del material son dos limitaciones para su aplicación en la producción de biomateriales, debido a que pueden llevar al desgate de las estructuras y generar discomfort en el paciente. Uno de los objetivos de esta tesis fue el desarrollo por fabricación aditiva de nuevos materiales híbridos a base de zirconia y polímeros acrilatos para simular las propiedades mecánicas y la buena biocompatiblidad características de los dientes naturales. La primera parte estuvo enfocada en el desarrollo de dichos materiales, con la elaboración de redes cerámicas infiltradas por polímeros (PICN), en las cuales una estructura cerámica porosa sinterizada es interprenetada por una matriz de polímero. La innovación fue el diseæo de andamios de zirconia (3Y-TZP), impresas tridimensionalmente y con porosidad controlada y ajustada. Después de la optimización de impresión, se decidió trabajar con un porcentaje de relleno del 50 % de zirconia para obtener la porosidad adecuada de la matriz, que fue después infiltrada con dimetacrilato de glicerolato de bisfenol A y trietilenglicol dimetacrilato (Bis-GMA y TEGDMA).Tras la producción de las estructuras PICN y la infiltración del copolímero, los materiales generados fueron completamente caracterizados por técnicas físico-químicas y las propiedades mecánicas fueron analizadas. Ensayos de adhesión bacteriana fueron llevados a cabo con las bacterias Escherichia coli (Gram-negativa) y Stretoccocus salivarius (Gram-positiva) concluiendo que, a pesar de la ausencia de efecto antibacteriano del material híbrido, tampoco existe una promoción del crecimiento bacteriano en dicha superficie. Respecto a la biocompatibilidad, experimentos con la línea celular MG-63 mostraron altos porcentajes de viabilidad celular. Para mejorar las propiedades antimicrobianas de las PICN, la superficie fue modificada con nanopartículas de plata, las cuales fueron embebidas en una matriz de lignina modificada enziméticamente con fenolatos (Ag@PL NPs) para evitar su oxidación. La funcionalización de la superficie del material híbrido con dichas nanopartículas permitió reducir el crecimiento bacteriano en un 90 %, respecto a la superficie no modificada. La última parte de la tesis estuvo enfocada en realizar mejoras en la oseointegración de la zirconia in vitro. Apesar de que es un material inerte, funcionalización de su superficie es recommendable para evitar futuros rechazos de la zirconia una vez implantada in vivo. Un copolímero de metacrilato de polidopamina, el cual previene la formación de biopelículas bacterianas, fue escogido para recubrir la superficie de zirconia. La caracterización demostró una gran adhesión del nuevo polímero, generado por plasma frío, a la superficie plana de discos de zirconia, además de una buena viabilidad de las células de la línea MG-63, en principio atribuída a la presencia de la polidopamina. En conclusión, esta tesis describe el proceso de impresión 3D de estructuras PICN, las cuales tienen una estructura macroporosa para la correcta infiltración del copolímero. La sinergia y la buena adherencia entre estos distintos materiales ha dado origen a un prototipo cuyas propiedades mecánicas simulan aquellas descritas para los dientes naturales. Además, las modificaciones de la superficie de la zirconia (plana o en format 3D filamentoso) con el fin de mejorar las propiedades del composite, ha resultado sactisfactoria para profundizar dicha investigación en el campo odontológico, permitiendo nuevas vías para ampliar el espectro de aplicaciones de dichos materiales híbridos en otros campos biomédicos.Polímers i biopolímer

Digital light processing-3D printing of thermoset materials with high biodegradability from amino acid-derived acrylamide monomers

Six acrylamide resins, derived from l-phenylalanine and l-leucine, are designed for application in digital light processing (DLP) printers to obtain biodegradable thermoset polymers. The acrylamide copolymers are prepared under light irradiation at 405 nm and thermal post-curing processes. Low molecular weight poly(ethylene glycol)diacrylate (PEGDA) and N,N-dimethylacrylamide (DMAM), both liquid resins, are used as co-monomers and diluents for the amino acid-derived acrylamide solubilization. The presence of two phenylalanine units and two ester groups in the acrylamide monomer accuses a fast degradation rate in hydrolytic medium in 90 days. The residual products leached in the aqueous media prove to be non-cytotoxic, when 3D-printed samples are cultured with osteoblast cells (MG63), which represents an advantage for the safe disposal of printer waste materials. The scaled-up pieces derived from l-phenylalanine and diethylene glycol, as amino acid-derived acrylamide (named compound C), PEGDA and DMAM, present high dimensional stability after DLP printing of complex structures used as testing samples. Layers of 50 µm of thickness are well cohesive having isotropic behavior, as demonstrated with tensile-strain measurements performed in X–Y–Z (plane) directions. The compound C, which contains phenylalanine amino acid, reveals a promising potential to replace non-biodegradable acrylate polymers used in prototyping systems.Postprint (author's final draft

Towards the development of Bacillus subtilis as a cell factory for membrane proteins and protein complexes

Background: The Gram-positive bacterium Bacillus subtilis is an important producer of high quality industrial enzymes and a few eukaryotic proteins. Most of these proteins are secreted into the growth medium, but successful examples of cytoplasmic protein production are also known. Therefore, one may anticipate that the high protein production potential of B. subtilis can be exploited for protein complexes and membrane proteins to facilitate their functional and structural analysis. The high quality of proteins produced with B. subtilis results from the action of cellular quality control systems that efficiently remove misfolded or incompletely synthesized proteins. Paradoxically, cellular quality control systems also represent bottlenecks for the production of various heterologous proteins at significant concentrations. Conclusion: While inactivation of quality control systems has the potential to improve protein production yields, this could be achieved at the expense of product quality. Mechanisms underlying degradation of secretory proteins are nowadays well understood and often controllable. It will therefore be a major challenge for future research to identify and modulate quality control systems of B. subtilis that limit the production of high quality protein complexes and membrane proteins, and to enhance those systems that facilitate assembly of these proteins.

Identification of the Slovak traditional cheese “Parenica” microflora

Numerous studies have demonstrated the higher accuracy, faster time-to-results and lower costs provided by MALDI Biotyper systems compared to classical methods. In this study, the culturable population of total count of bacteria, enterococci, coliforms bacteria, lactic acid bacteria (LAB) and microscopic fungi and yeasts from cow’s dairy products was identified using the MALDI-TOF MS Biotyper. Altogether, 50 samples of the Slovak cheese “Parenica” were examined. Total numbers of bacteria were cultured on Plate count agar at 37 °C for 24–48 h, aerobically; enterococci were cultured on Enterococcus selective agar at 37 °C for 24–48 h, aerobically; coliforms bacteria were cultured on Violet Red Bile lactose agar at 37 °C for 24–48 h, aerobically. The LAB were cultured on MRS (Main Rogosa agar), MSE and APT agar at 30 °C in microaerophilic conditions. The microscopic fungi and yeasts were cultured on Malt extract agar at 25 °C for 5 days, aerobically. Isolated strains (total 669) were subjected to identification by the MALDI-TOF MS. Among total count the identified bacteria mostly were Acinetobacter baumannii, Bacillus cereus, Micrococcus luteus and Staphylococcus warneri. Escherichia coli and Enterobacter cloacae were the most abundant coliform bacteria representatives identified. Coliform bacteria included Citrobacter, Hafnia and Klebsiella. Altogether three genera belonged to the LAB – Lactobacillus, Lactococcus and Leuconostoc were identified with Lactococcus lactis, Lactobacillus plantarum, Lactobacillus coryniformis, L. fructivorans and Leuconostoc mesenteroides were considered as the dominated LAB species in dairy products. Among yeasts, Kluyveromyces lactis, Candida zeylanoides and Yarrowia lipolytica were among the most isolated

The World Spider Trait database: a centralized global open repository for curated data on spider traits

Spiders are a highly diversified group of arthropods and play an important role in terrestrial ecosystems as ubiquitous predators, which makes them a suitable group to test a variety of eco-evolutionary hypotheses. For this purpose, knowledge of a diverse range of species traits is required. Until now, data on spider traits have been scattered across thousands of publications produced for over two centuries and written in diverse languages. To facilitate access to such data, we developed an online database for archiving and accessing spider traits at a global scale. The database has been designed to accommodate a great variety of traits (e.g. ecological, behavioural and morphological) measured at individual, species or higher taxonomic levels. Records are accompanied by extensive metadata (e.g. location and method). The database is curated by an expert team, regularly updated and open to any user. A future goal of the growing database is to include all published and unpublished data on spider traits provided by experts worldwide and to facilitate broad cross-taxon assays in functional ecology and comparative biology.Fil: Pekár, Stano. Masaryk University; República ChecaFil: Wolff, Jonas O. University of Greifswald; AlemaniaFil: Cernecká, L'udmila. Slovak Academy of Sciences; ArgentinaFil: Birkhofer, Klaus. Brandenburgische Technische Universität Cottbus; AlemaniaFil: Mammola, Stefano. University of Helsinki; FinlandiaFil: Lowe, Elizabeth C.. Macquarie University; AustraliaFil: Fukushima, Caroline S.. University of Helsinki; FinlandiaFil: Herberstein, Marie E.. Macquarie University; AustraliaFil: Kucera, Adam. Masaryk University; República ChecaFil: Buzatto, Bruno A.. University of Western Australia; AustraliaFil: Djoudi, El Aziz. Brandenburgische Technische Universität Cottbus; AlemaniaFil: Domenech, Marc. Universidad de Barcelona; EspañaFil: Enciso, Alison Vanesa. Fundación Protectora Ambiental Planadas Tolima; ColombiaFil: Piñanez Espejo, Yolanda María Guadalupe. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Nordeste. Instituto de Biología Subtropical. Instituto de Biología Subtropical - Nodo Posadas | Universidad Nacional de Misiones. Instituto de Biología Subtropical. Instituto de Biología Subtropical - Nodo Posadas; ArgentinaFil: Febles, Sara. No especifíca;Fil: García, Luis F. Universidad de la República; UruguayFil: Gonçalves Souza, Thiago. Universidad Federal Rural Pernambuco; BrasilFil: Isaia, Marco. Università di Torino; ItaliaFil: Lafage, Denis. Universite de Rennes I; FranciaFil: Líznarová, Eva. Masaryk University; República ChecaFil: Macías Hernández, Nuria. Universidad de La Laguna; EspañaFil: Fiorini de Magalhaes, Ivan Luiz. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Museo Argentino de Ciencias Naturales "Bernardino Rivadavia"; ArgentinaFil: Malumbres Olarte, Jagoba. Universidade Dos Açores; PortugalFil: Michálek, Ondrej. Masaryk University; República ChecaFil: Michalik, Peter. ERNST MORITZ ARNDT UNIVERSITÄT GREIFSWALD (UG);Fil: Michalko, Radek. No especifíca;Fil: Milano, Filippo. Università di Torino; ItaliaFil: Munévar, Ana. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Nordeste. Instituto de Biología Subtropical. Instituto de Biología Subtropical - Nodo Puerto Iguazú | Universidad Nacional de Misiones. Instituto de Biología Subtropical. Instituto de Biología Subtropical - Nodo Puerto Iguazú; ArgentinaFil: Nentwig, Wolfgang. University of Bern; SuizaFil: Nicolosi, Giuseppe. Università di Torino; ItaliaFil: Painting, Christina J. No especifíca;Fil: Pétillon, Julien. Universite de Rennes I; FranciaFil: Piano, Elena. Università di Torino; ItaliaFil: Privet, Kaïna. Universite de Rennes I; FranciaFil: Ramirez, Martin Javier. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Museo Argentino de Ciencias Naturales "Bernardino Rivadavia"; ArgentinaFil: Ramos, Cândida. No especifíca;Fil: Rezác, Milan. No especifíca;Fil: Ridel, Aurélien. Universite de Rennes I; FranciaFil: Ruzicka, Vlastimil. No especifíca;Fil: Santos, Irene. No especifíca;Fil: Sentenská, Lenka. Masaryk University; República ChecaFil: Walker, Leilani. No especifíca;Fil: Wierucka, Kaja. Universitat Zurich; SuizaFil: Zurita, Gustavo Andres. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Nordeste. Instituto de Biología Subtropical. Instituto de Biología Subtropical - Nodo Posadas | Universidad Nacional de Misiones. Instituto de Biología Subtropical. Instituto de Biología Subtropical - Nodo Posadas; ArgentinaFil: Cardoso, Pedro. No especifíca

Significant factors of violence against women in urban and rural community

Introduction. The research is focused on the issue of domestic violence against women. It deals with the definition of violence, concepts and models of individual areas by summarising the research findings and the possibilities of methodological tools for measurement of significant factors of violence against women. Aim. The primary goal of the research is to define significant factors which determine violence against women. Materialand Methods. Methods of research – survey, document analysis and database statistical analysis. Results. Primary results of quantitative research reveal that women of all ages and educational groups are at risk. Mostly women aged 26–45, living in rural areas with middle school education without maturity exam (final exam). Violence in families involves men of all age groups with emphasis on increased incidence in specific categories: mostly men aged 36–45, living in rural areas with secondary (high school or comprehensive school) education. Another field of interest represents analysis of negative family situations, impact of violence against woman on her psychological conditions, and reasons why victims carry on marriage and/or partnership. Conclusions. It can be concluded that the most frequent negative phenomena during aggressor's and/or victim's childhood were physical violence of father against mother, alcohol – possibly father's alcoholism, poverty, physical punishment of children, and patriarchal model of the family. Two thirds of victims continue marriage/partnership in order to maintain the family, to keep the father for children, and for financial reasons. There is a frequent social criminality in poor biological families of aggressors, i.e., a commission of crime because of lack of finances

KOMPARACIA VYBRANYCH UKAZOVATEL'OV KOMODITY HOVADZI DOBYTOK

Cattle breeding and mainly cattle for fattening is significantly affected by the development of social, economic, structural and other changes. Among negative results of this development are serious reductions in milk consumption and the number of cattle, with the adverse effect on usage of soil and permanent grasslands, as well as on the employment in the agrarian sector. Considering the production and out-of-production functions performed by the breeding of cattle, it is necessary to achieve its stability in all categories, to increase domestic milk and beef consumption, and to improve production and reproduction indexes, which have a serious impact on production economy and thus on competitivness in relation to cattle meat producers in the EU. From the short-term aspect it is possible to solve beef shortage by importing slaughter cattle with a lower carcass weight. However, this alternative can only be considered in case that a sufficient number of slaughter animals is available. A serious decline in the number of slaughter cattle can influence in the future the foreign trade with this commodity and a total increase in passive balance in a similar way to slaughter pigs where the import of 60 ths. tons of pork is expected along with a growth in grain export. From the above it follows that the export of basic agricultural stock is increasing and more value-added products are being imported, which can be considered to be a very unfavourable state in terms of the present development of the Slovak agriculture

INTERKULTURNA SPOLUPRACA V MEDZINARODNE CINNYCH PODNIKOCH

The paper deals with intercultural communication and teamwork in a foreign company situated on Slovak market as one of the subsidiary corporations. The main aim is to review current situation in the field of intercultural communication, cooperation, and teamwork in this company. Following suggestion was made on the basis of the results of our analyses: to organize intercultural trainings: language-teaching, informative training with orientation on culture, and intercultural "assimilation maker'' actuating in intercultural heterogeneous team. Next suggestion is to decrease the number of members in one team to make teamwork more effective. All the above mentioned suggestions should help exploit the potential of human resources in the company, as well as effectively solve problems in the field of intercultural communication and co-operation

FOOD QUALITY AND FOOD QUALITY MARKS FROM THE CONSUMERS POINT OF VIEW IN THE CONDITION OF SLOVAKIA AND THE CZECH REPUBLIC

Food quality is the subject of interest in many countries. Slovakia and Czech Republic implemented the national programs promoting domestic agricultural commodities and food in order to increase the quality and safety of domestic products and support their competitiveness on the domestic and foreign markets. Food products in Slovakia and Czech Republic are labeled by the quality marks that represent the quarantee of their high quality, safety and domestic origin. Promotion of these quality products is ensured through various media campaigns and exhibitions that take place in different countries across Europe. The paper focuses on food quality and Food Quality Policy in Slovakia and Czech Republic and consumer's attitudes towards the food quality and products bearing food quality marks in their home country