Magnetic Properties of Hausmannite Thin Films

The magnetic properties of hausmannite thin films are investigated in this chapter. The Verdet constant and angle of Faraday rotation are determined. The magnetic anisotropy of Mn3O4 is explained by the measurement of the zero-field cooled (ZFC) and field cooled (FC) curves. This experiment is connected with the presentation of the ferromagnetic to superparamagnetic transition of the hausmannite

Hydrogel dressings for advanced wound management

The published manuscript is available at EurekaSelect via http://www.eurekaselect.com/openurl/content.php?genre=article&doi=10.2174/0929867324666170920161246Composed in a large extent of water and due to their non-adhesiveness, hydrogels found their way to the wound dressing market as materials that provide a moisture environment for healing while being comfortable to the patient. Hydrogels’ exploitation is constantly increasing after evidences of their even broader therapeutic potential due to resemblance to dermal tissue and ability to induce partial skin regeneration. The innovation in advanced wound care is further directed to the development of so-called active dressings, where hydrogels are combined with components that enhance the primary purpose of providing a beneficial environment for wound healing. The aim of this mini-review is to concisely describe the relevance of hydrogel dressings as platforms for delivery of active molecules for improved management of difficult-to-treat wounds. The emphasis is on the most recent advances in development of stimuli-responsive hydrogels, which allow for control over wound healing efficiency in response to different external modalities. Novel strategies for monitoring of the wound status and healing progress based on incorporation of sensor molecules into the hydrogel platforms are also discussed.Peer ReviewedPostprint (author's final draft

Sonochemical synthesis and stabilization of concentrated antimicrobial silver-chitosan nanoparticle dispersions

This work reports on a green synthetic route to produce concentrated aqueous dispersions of silver nanoparticles (AgNP) employing high-intensity ultrasound (US) and chitosan (CS) as a non-toxic reducing agent for Ag1 salts and AgNP stabilizer. The sonication simultaneously boosted the synthesis and improved the stability of the AgNP, capping them with CS. Hybrid AgNP-CS antimicrobial dispersions, stable for at least 6 months, were synthesized in a simple single step process. The use of US allowed for applying relatively mild processing temperatures (608C) and reaction time between 30 min and 3 h to obtain concentrated disper- sions of AgNP that otherwise could not be obtained even after 72 h under mechanical stirring at the same reaction conditions. Upon sonication spherical AgNP-CS with a size between 60 and 100 nm were generated, in contrast to the average diameter of 200 nm of the particles obtained by stirring. The antibacterial efficiency of the AgNP-CS hybrids was evaluated against the medically relevant pathogens Staphylococcus aureus and Escherichia coli. The US-synthesized AgNP-CS showed more than 3-fold higher antibacterial activity compared to the particles obtained under stirring, due to their higher concentration and smaller size.Postprint (author's final draft

Bottom-up layer-by-layer assembling of antibacterial freestanding nanobiocomposite films

In this study, freestanding nanobiocomposite films were obtained by the sequential deposition of biopolymer-capped silver nanoparticles (AgNPs) and hyaluronic acid (HA). At first, dispersions ofAgNPs decorated with chitosan (CS) or aminocellulose (AC) were synthesized by applying high intensity ultrasound. These polycationic nanoentities were layer-by-layer assembled with the HA polyanion to generate stable 3D supramolecular constructs, where the biopolymer-capped AgNPs play the dual role of active agent and structural element. SEM images of the assemblies revealed gradual increase of thickness with the number of deposited bilayers. The composites of =50 bilayers were safe to human cells and demonstrated 100% antibacterial activity against Staphylococcus aureus and Escherichia coli. Moreover, the films containing CSAgNPs brought about the total prevention of biofilm formation reducing the cells surface adherence by up to 6 logs. Such nanobiocomposites could serve as an effective barrier to control bacterial growth on injured skin, burns, and chronic wounds.Peer ReviewedPostprint (author's final draft

AGE-RELATED DIFFERENCES IN THE DEVELOPMENT OF MOTOR ABILITIES IN VOLLEYBALL

There are a large number of publications related to conditioning in volleyball and in general. However, a very small part of them are related to the development of motor abilities in an age aspect. Such a study would be very difficult to implement, but at the same time, it would be beneficial in terms of the selection and sports orientation of youth volleyball. Volleyball as a sport has developed extremely dynamically in recent years, which makes it even more demanding in terms of fitness. The basic skills necessary for successful implementation in sports are complex and based on the athletes' ability to jump, sprint, and hit. From this point of view, the interest in this research was dictated, with the primary goal of determining the values of the main signs related to the volleyball game and compiling normative tables for control and assessment of preparedness. The research tasks also arise from the goal set in this way. To investigate the differences in the main essential characteristics of the volleyball game regarding age. To propose standards of control and evaluation. The methods we used to solve the problems are anthropometry, chronometry, tensiometry, speedometry, and mathematical-statistical methods (frequency, variation analysis, and sigma method). Results: The most significant increase in women was observed in the results of the jump tests and the speed of the serve (over 20 %) and smaller within 10% in the running tests. We attribute these results to the fact that the listed movements emphasize the training and competition process. Based on the obtained results, norms for evaluating the readiness of the contestants have been drawn up

Surface nano-structured materials to control bacterial contamination

The spread of bacteria and infections, initially associated with an increased number of hospital-acquired infections, has now extended into the community causing severe and difficult to treat diseases. Additionally, many of those diseases are evoked by bacteria that have become resistant to antibiotics. Overcoming the ability of bacteria to develop resistance will potentially reduce the burden of these infections on the healthcare systems worldwide and prevent thousands of deaths each year. The nano-scale particles are promising candidates to fight bacteria, since developing of resistance to their action is less likely to occur. Nanoparticles (NPs) can be incorporated into polymeric matrices to design a wide variety of nanocomposites. Such nano-structures consisting of inorganic and inorganic/organic NPs represent a novel class of materials with a broad range of applications. This thesis is about the development of antibacterial nano-structured materials aimed at preventing the spread of bacteria. To achieve this, two versatile physicochemical and biotechnological tools, namely sonochemistry and biocatalysis were innovatively combined. Ultrasound irradiation used for the generation of various nano-structures and its combination with biocatalysts (enzymes) opens new perspectives in materials processing, here illustrated by the production of NPs coated medical textiles, water treatment membranes and chronic wound dressings. The first part of the thesis aims at the development of antibacterial medical textiles to prevent the bacteria transmission and proliferation using two single step approaches for antibacterial NPs coating of textiles. In the first approach antibacterial zinc oxide NPs (ZnO NPs) and chitosan (CS) were deposited simultaneously on cotton fabric by ultrasound irradiation. The obtained hybrid NPs coatings demonstrated durable antibacterial properties after multiple washing cycles. Moreover, the presence of biopolymer in the NP hybrids improved the biocompatibility of the material in comparison with ZnO NPs coating alone. In the second approach, a simultaneous sonochemical/enzymatic process for durable antibacterial coating of cotton with ZnO NPs was carried out. The enzymatic treatment provides better adhesion of the ZnO NPs and, as a consequence, enhanced coating stability during exploitation. Likewise to the antibacterial coatings obtained in the first approach, the antibacterial efficiency of these textiles was maintained after multiple intensive laundry regimes used in hospitals. The NPs-coated cotton fabrics inhibited the growth of the most medically relevant bacteria species. In the second part of the thesis, hybrid antibacterial biopolymer/silver NPs and cork matrices, were enzymatically assembled into an antimicrobial material with potential for water remediation. Intrinsically antibacterial amino-functional biopolymers, namely CS and aminocellulose were used as doping agents to stabilize colloidal dispersions of silver NPs (AgNPs), additionally providing the particles with functionalities for covalent immobilization on cork to impart durable antibacterial effect. The biopolymers promoted the antibacterial efficacy of the obtained nanocomposites in conditions simulating a real situation in constructed wetlands. In the last, third part of the thesis, a bioactive nanocomposite hydrogel for wound treatment was developed. Sonochemically synthesized epigallocatechin gallate nanospheres (EGCG NSs) were incorporated and simultaneously crosslinked enzymatically into a thiolated chitosan hydrogel. The potential of the generated material for chronic wound treatment was evaluated by assessing its antibacterial properties and inhibitory effect on myeloperoxidase and collagenase biomarkers of chronic wound infection. Sustained release of the EGCG NSs from the biopolymer matrix was achieved. The latter, coupled with the good biocompatibility of the hydrogel, suggested its potential for chronic wound management.La propagación de bacterias e infecciones, inicialmente limitada a infecciones adquiridas en el hospital, se ha extendido al resto de la sociedad causando enfermedades muy graves y más difíciles de tratar. Además, muchas de estas enfermedades son provocadas por bacterias que se han hecho resistentes a los antibióticos convencionales. Por lo tanto, limitar la capacidad de estas bacterias para desarrollar resistencia puede potencialmente reducir la alta incidencia de estas infecciones y evitar miles de muertes cada año. Las partículas de escala nanométrica son unas candidatas prometedoras para combatir las bacterias, ya que su mecanismo de acción las hace disminuir las probabilidades en el desarrollo de resistencia. Las nanopartículas (NPs) se pueden incorporar en matrices poliméricas para diseñar una amplia variedad de materiales nanocompuestos. Estas nanoestructuras consisten en NPs orgánicas/inorgánicas e inorgánicas representando una nueva clase de materiales con una amplia gama de aplicaciones. Esta tesis trata sobre el desarrollo de materiales antibacterianos con estructura nanométrica dirigidos a prevenir la propagación de bacterias. Para lograr esto, dos herramientas fisicoquímicas y biotecnológicas versátiles tales como sonoquímica y biocatálisis, se combinaron de manera innovadora. La irradiación por ultrasonido se ha utilizado para la generación de nanoestructuras diversas y su combinación con biocatalizadores (enzimas) abre nuevas perspectivas en el tratamiento de materiales, aquí ilustrados por la producción de textiles médicos recubiertos con NPs, membranas de tratamiento de agua y apósitos para heridas crónicas. La primera parte de la tesis tiene como objetivo el desarrollo de textiles médicos antibacterianos para prevenir la transmisión y proliferación de bacterias utilizando dos estrategias "de un solo paso" para el recubrimiento antibacteriano de estos textiles con NPs. En el primer enfoque NPs antibacterianas de óxido de zinc (ZnO NPs) y quitosano (CS) fueron depositadas simultáneamente sobre tejido de algodón por irradiación de ultrasonido. Los recubrimientos híbridos de NPs obtenidos demostraron propiedades antibacterianas duraderas después de varios lavados exhaustivos. Por otra parte, la presencia de biopolímeros en las NPs híbridas mejoraba la biocompatibilidad del material en comparación con el recubrimiento de solamente de ZnO NPs. En la segunda parte de la tesis, híbridos antibacterianos hechos de biopolímeros y NPs de plata y matrices de corcho, fueron ensamblados enzimáticamente en un material antimicrobiano para su utilización en la remediación de aguas. Biopolímeros antibacterianos aminofuncionalizados (CS y aminocelulosa) se utilizaron como agentes dopantes para estabilizar las dispersiones coloidales de plata (Ag NPs). Además, estas partículas presentan todas las funciones necesarias para su inmovilización covalente en el corcho proporcionando un efecto antibacteriano duradero. Estos biopolímeros aumentaron la eficacia antibacteriana de estos nanocompuestos en condiciones que simulan una situación real en humedales construidos. En la tercera parte de la tesis, se desarrolló un hidrogel nanocompuesto bioactivo para el tratamiento de heridas crónicas. Nanoesferas de galato de epigalocatequina (EGCG NSs) fueron sintetizadas a través de sonoquimica y se incorporaron y simultáneamente reticularon enzimáticamente en un hidrogel de quitosano tiolado. El potencial del material generado para el tratamiento de heridas crónicas fue evaluado por sus propiedades antibacterianas y su efecto inhibidor sobre biomarcadores producidos en heridas crónicas infectadas (mieloperoxidasa y colagenasa). También se consiguió la liberación sostenida de EGCG NSs por parte de la matriz generada, que junto con su buena biocompatibilidad, demostraba su potencial para el tratamiento de heridas crónicas

Governo, gestione, tutela e valorizzazione delle risorse territoriali: la Bulgaria nel contesto della politica di sviluppo rurale dell'Unione Europea. Un caso di cooperazione transnazionale.

ABSTRACT La politica di sviluppo rurale della Bulgaria cerca di sfruttare i punti di forza delle zone rurali per innescare uno sviluppo inclusivo che porti benessere e opportunità, potenziando competitività e diversificazione del settore agroalimentare e migliorando la qualità della vita. Dopo l’ingresso nell’Unione europea, tale strategia si è dovuta integrare nella politica di sviluppo rurale europea, che riconosce l’importanza delle aree rurali e il bisogno di affrontarne i problemi in maniera comprensiva. Suo tratto caratteristico è l’approccio LEADER, che vuole sviluppare le aree rurali anche creando Gruppi di Azione Locale (GAL), col compito di integrare misure settoriali distinte e di coinvolgere i diversi attori economici e sociali. La strategia di sviluppo rurale europea è stata una delle politiche che hanno avuto un maggiore impatto sulle condizioni di vita delle popolazioni rurali bulgare. Mentre le autorità centrali cercano di mantenerne il controllo e di utilizzare i fondi europei per legittimarsi, i GAL si sono dimostrati cpaci di aderire il più possibile alle caratteristiche e ai bisogni del territorio, anche tramite collaborazioni transazionali, che hanno rivelato affinità impensate, come nel progetto Cross Border for Rural Identities Development – Adriatic Sea/Black Sea. ABSTRACT in English The rural development policy in Bulgaria seeks to exploit the strengths of rural areas to trigger inclusive development that brings wealth and opportunity, enhancing competitiveness and diversification of the agriculture sector and improving the quality of life. After joining the European Union, this strategy has had to integrate into the European rural development policy, which recognizes the importance of rural areas and the need to tackle its problems in a comprehensive manner. Its characteristic feature is the LEADER approach, which wants to develop the rural areas also creating Local Action Groups (LAGs), with the task of integrating sectoral measures distinct and involve different economic and social actors. The rural development strategy in Europe was one of the policies that have had a greater impact on the living conditions of rural populations Bulgarian. While the central authorities are trying to maintain control and to use European funding to legitimize itself, the LAGs have proven cpaci to adhere as much as possible to the characteristics and needs of the territory, also through collaborations transactional, which revealed unexpected affinities, as in Cross Border Identities project for Rural Development - Adriatic Sea / Black Sea

Enzyme-assisted formation of hybrid biopolymer hydrogels incorporating active phenolic nanospheres

This work is about the synthesis of hybrid nanocomposite hydrogels comprising a thiolated chitosan platform that incorporates epigallocatechin gallate nanospheres as active polyphenolic agents for wound healing applications. The phenolic nanospheres were prepared using an industry-attractive, low-cost and fast sonochemical technology, whereas the gel formation was achieved via a green approach involving the enzymatic cross-linking with horseradish peroxidase, avoiding the use of harsh chemical cross-linkers. The superior functional properties of the phenolic nanospheres compared to their molecular counterparts are demonstrated by better attenuation of the chronicity factors found in non-healing wounds. Release of the intact and functional phenolic nanospheres coupled to good biocompatibility of the system during several days, reveals potential of this hybrid material as a dressing with prolonged activity for chronic wound management.Peer ReviewedPostprint (published version

Enzyme-assisted formation of hybrid biopolymer hydrogels incorporating active phenolic nanospheres

This work is about the synthesis of hybrid nanocomposite hydrogels comprising a thiolated chitosan platform that incorporates epigallocatechin gallate nanospheres as active polyphenolic agents for wound healing applications. The phenolic nanospheres were prepared using an industry-attractive, low-cost and fast sonochemical technology, whereas the gel formation was achieved via a green approach involving the enzymatic cross-linking with horseradish peroxidase, avoiding the use of harsh chemical cross-linkers. The superior functional properties of the phenolic nanospheres compared to their molecular counterparts are demonstrated by better attenuation of the chronicity factors found in non-healing wounds. Release of the intact and functional phenolic nanospheres coupled to good biocompatibility of the system during several days, reveals potential of this hybrid material as a dressing with prolonged activity for chronic wound management.Peer Reviewe