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In this study, we developed sodium alginate-chitosan hydrogels using a microwave-assisted synthesis method, aligning with green chemistry principles for enhanced sustainability. This eco-friendly approach minimizes chemical use and waste while boosting efficiency. A curcumin:2-hydroxypropyl-β-cyclodextrin complex was incorporated into the hydrogels, significantly increasing the solubility and bioavailability of curcumin. Fourier Transform Infrared Spectroscopy (FTIR) analysis confirmed the structure and successful incorporation of curcumin, in both its pure and complexed forms, into the polymer matrix. Differential scanning calorimetry revealed distinct thermal transitions influenced by the hydrogel composition and physical cross-linking. Hydrogels with higher alginate content had higher swelling ratios (338%), while those with more chitosan showed the lowest swelling ratios (254%). Scanning Electron Microscopy (SEM) micrographs showed a porous structure as well as successful incorporation of curcumin or its complex. Curcumin release studies indicated varying releasing rates between its pure and complexed forms. The chitosan-dominant hydrogel exhibited the slowest release rate of pure curcumin, while the alginate-dominant hydrogel exhibited the fastest. Conversely, for curcumin from the inclusion complex, a higher chitosan proportion led to the fastest release rate, while a higher alginate proportion resulted in the slowest. This study demonstrates that the form of curcumin incorporation and gel matrix composition critically influence the release profile. Our findings offer valuable insights for designing effective curcumin delivery systems, representing a significant advancement in biodegradable and sustainable drug delivery technologies.

The human resources or the human capital can be regarded as a driving force of the modern organizations’ development. At the same time, the training of employees is observed and defined as a necessary prerequisite for their development and realization of both personal (professional) and organizational goals. Moreover, contemporary authors believe that the competitive advantage of organizations in the global economy and industry 4.0 depends on the competencies, knowledge, skills and willingness of employees to respond to the challenges of turbulent economic environment and scientific and technological development. Special attention should be payed to the obligations and responsibilities of the organization to provide the material and organizational conditions necessary for modern education and learning; provide a positive learning climate; motivate employees to learn permanently; stimulate the application of acquired knowledge; require and encourage a continuous education of managers, etc. Organizations that respect this concept promote learning as a fundamental element of the current business strategy and as a fundamental basis of their development and business efficiency in the future. However, relevant sources indicate that the modern business environment suffers from numerous weaknesses and shortcomings in the organization and implementation of the employee training. Starting from that, the paper elaborates the basic characteristics and phases of training management with a special emphasis on the transfer of training as an integral part of the management strategy in a modern business environment.

In the spacious inundation area on the left bank of the lower course of the Sava River in Serbia, there is an abandoned meander Special Nature Reserve, “Obedska bara”, which represents a very important floodplain in this part of Europe. This area is characterized by an exceptional wealth of biodiversity with a significant presence of rare and endangered species of national and international importance. Hydrological conditions in the mentioned area were analyzed from the aspect of surface water movement in nature and conditions altered by human factors (after the construction of the road network, canals, etc.). The movement of surface water, i.e., the filling and emptying of the investigated area, parallel to the water level of the Sava River, is shown using a digital terrain model. Our simulation of the change in surface water level within the studied area included the display of underwater areas, both with the formation of a flood wave (i.e., increasing water level of the Sava) and with the outflow of water from the pond when the water level in the Sava was reduced in both scenarios (natural and conditions altered by human factors). GIS and terrain digitalization were used for geospatial and hydrological analyses and, based on this, maps that display endangered areas could be made. The obtained results show that the largest human impact was recorded at the water level of the Sava River 74 m above sea level. The aforementioned water regime changes were shown to negatively affect dominant vegetation, such as pedunculate oak and ash.

Izhodišča: Bolniki s plevralnim izlivom pogosto potrebujejo razbremenilno plevralno punkcijo (RPP), po kateri navajajo bolj ali manj izrazito olajšanje dispneje. Zaradi varnosti se priporoča, da se med RPP odstrani do 1.500 mL tekočine. Metode: V raziskavo smo vključili 96 bolnikov, pri katerih je bila potrebna RPP. Zbirali smo ocene stopnje dispneje na lestvici VAS pred, takoj po in 2 uri po RPP, pri 73 bolnikih pa še 24 ur po RPP ter beležili količino odstranjene tekočine. Med RPP smo z vodnim manometrom merili plevralne tlake, iz katerih smo izračunali elastanco plevralnega prostora in na podlagi meritev bolnike razdelili v skupine z različnimi elastančnimi krivuljami. Rezultati: Med začetnim plevralnim tlakom in količino odstranjene tekočine ter olajšanjem dispneje po opravljeni RPP smo ugotovili statistično značilno povezanost. Pri največjem deležu bolnikov smo RPP zaključili zaradi pojava simptomov, zaradi meritev plevralnega tlaka pa smo RPP prekinili pri 16 bolnikih (16,7 %). V skupino z normalno elastančno krivuljo smo uvrstili 74 bolnikov, nezmožnost razpenjanja pljuč pa smo ugotovili pri 22 bolnikih. Med RPP ni bilo pomembnih zapletov, kljub temu da smo več kot 1.500 mL izliva odstranili pri 32 (33 %) bolnikih. Zaključek: Višji začetni plevralni tlak je šibko povezan z višjo začetno stopnjo dispneje in večjim olajšanjem dispneje po opravljeni RPP. Najbolj uporabna je dinamika sprememb plevralnega tlaka, s katero lahko že med RPP prepoznamo nezmožnost razpenjanja pljuč. Med RPP s plevralno manometrijo lahko varno odstranimo tudi več kot 1.500 mL tekočine.

Anatomical properties of pedunculate oak (Quercus robur L.) wood have not been previously investigated in Serbia, so bearing in mind economic-productive and ecological significance of this species, it was one of the main reasons why this research was conducted. In this paper, fibre length (FL), double cell-wall thickness (DCWT) and fibre lumen diameter (FLD) were measured in pedunculate oak wood from two different sites. The study was conducted at two sites (Donji Srem – MU „Raškovica-Smogvica” and Gornji Srem – MU „Kupinske grede”), situated along the Sava River and characterised by different ecological conditions, including flooding regimes. Measurements were conducted in radial direction, from pith to bark, in order to assess variation of investigated characteristics with cambial age, between two sites and between individual trees within each site. All measured characteristics from both sites increase going from pith to bark apart from FL in the area of Donji Srem – MU „Kupinske grede” that reaches maximum value in the central part of xylem and then decreases. Hydrological site conditions affect the dimensions of pedunculate oak wood fibres and these values are a bit higher in Gornji Srem – MU „Raškovica-Smogvica”, due to a greater quantity of available water.

Background The relationship between anti-SARS-CoV-2 humoral immune response, pathogenic inflammation, lymphocytes and fatal COVID-19 is poorly understood. Methods A longitudinal prospective cohort of hospitalised patients with COVID-19 (n=254) was followed up to 35 days after admission (median, 8 days). We measured early anti-SARS-CoV-2 S1 antibody IgG levels and dynamic (698 samples) of quantitative circulating T-, B- and natural killer lymphocyte subsets and serum interleukin-6 (IL-6) response. We used machine learning to identify patterns of the immune response and related these patterns to the primary outcome of 28-day mortality in analyses adjusted for clinical severity factors. Results Overall, 45 (18%) patients died within 28 days after hospitalisation. We identified six clusters representing discrete anti-SARS-CoV-2 immunophenotypes. Clusters differed considerably in COVID-19 survival. Two clusters, the anti-S1-IgGlowestTlowestBlowestNKmodIL-6mod, and the anti-S1-IgGhighTlowBmodNKmodIL-6highest had a high risk of fatal COVID-19 (HR 3.36–21.69; 95% CI 1.51–163.61 and HR 8.39–10.79; 95% CI 1.20–82.67; p≤0.03, respectively). The anti-S1-IgGhighestTlowestBmodNKmodIL-6mod and anti-S1-IgGlowThighestBhighestNKhighestIL-6low cluster were associated with moderate risk of mortality. In contrast, two clusters the anti-S1-IgGhighThighBmodNKmodIL-6low and anti-S1-IgGhighestThighestBhighNKhighIL-6lowest clusters were characterised by a very low risk of mortality. Conclusions By employing unsupervised machine learning we identified multiple anti-SARS-CoV-2 immune response clusters and observed major differences in COVID-19 mortality between these clusters. Two discrete immune pathways may lead to fatal COVID-19. One is driven by impaired or delayed antiviral humoral immunity, independently of hyper-inflammation, and the other may arise through excessive IL-6-mediated host inflammation response, independently of the protective humoral response. Those observations could be explored further for application in clinical practice.

The purposes of this study are the polymerization of temperature-sensitive copolymers based on N-isopropyl acrylamide and 10 mol % of 2-hydroxypropylmethacrylate, characterisations of their thermal, morphological and swelling properties, as well as the analysis of potential application in drug-delivery systems. Acetaminophen, the representative of non-steroidal anti-inflammatory drugs, was used as a model drug in this study. It is a common pain relief drug, which is also used for fever treatment. However, oral administration comes with certain health risks, mainly the overdose and frequent administration of up to four times a day. The goal of applying temperature-sensitive hydrogel is to enable extended administration once a day, depending on the body temperature. The swelling behavior of the obtained poly(N-isopropyl acrylamide-co-2-hydroxypropylmethacrylate) (p(NIPA/HPMA)) hydrogels and their temperature-sensitivity, kinetics and order of swelling processes at 18 and 38 °C were analyzed. The thermal properties of these hydrogels were observed by the DSC method, and the obtained thermograms showed both melting and glass transitions. The drug delivery system of p(NIPA/HPMA) hydrogels with loaded acetaminophen was analyzed using scanning electron microscopy and Fourier transform infrared spectroscopy methods. Structural analysis of FTIR spectra indicates that non-covalent intermolecular interactions of the type of hydrogen bonds were formed among functional groups of acetaminophen and side-chains of p(NIPA/HPMA) hydrogels. The surface structure of p(NIPA/HPMA) hydrogels after drug loading indicates the acetaminophen presence into the pores of the hydrogel network, and their loading efficiency was higher than 92%. Qualitative and quantitative analysis of acetaminophen, determined by the high-pressure liquid chromatography method, showed that about 90–99% of the loaded amount was released from p(NIPA/HPMA) hydrogels within 24 h. Kinetic parameters of the acetaminophen release under simulated gastrointestinal conditions were determined. Based on obtained results, the drug delivery system of temperature-sensitive p(NIPA/HPMA) hydrogels with loaded acetaminophen could be suitable for additional investigation for modulated drug administration, e.g., for extended drug administration.

The aim of this study was to examine homopolymeric poly(N-isopropylacrylamide), p(NIPAM), hydrogels cross-linked with ethylene glycol dimethacrylate as carriers for sulfanilamide. Using FTIR, XRD and SEM methods, structural characterization of synthesized hydrogels before and after sulfanilamide incorporation was performed. The residual reactants content was analyzed using the HPLC method. The swelling behavior of p(NIPAM) hydrogels of different crosslinking degrees was monitored in relation to the temperature and pH values of the surrounding medium. The effect of temperature, pH, and crosslinker content on the sulfanilamide release from hydrogels was also examined. The results of the FTIR, XRD, and SEM analysis showed that sulfanilamide is incorporated into the p(NIPAM) hydrogels. The swelling of p(NIPAM) hydrogels depended on the temperature and crosslinker content while pH had no significant effect. The sulfanilamide loading efficiency increased with increasing hydrogel crosslinking degree, ranging from 87.36% to 95.29%. The sulfanilamide release from hydrogels was consistent with the swelling results—the increase of crosslinker content reduced the amount of released sulfanilamide. After 24 h, 73.3–93.5% of incorporated sulfanilamide was released from the hydrogels. Considering the thermosensitivity of hydrogels, volume phase transition temperature close to the physiological temperature, and the satisfactory results achieved for sulfanilamide incorporation and release, it can be concluded that p(NIPAM) based hydrogels are promising carriers for sulfanilamide.

The aim of the present study was to determine the content of residual monomer methyl methacrylate (MMA) in cold and hot polymerized poly(methyl methacrylate) (PMMA), both widely applicable in dentistry, by using MHE-GC-MS (multiple headspace extraction analysis by gas chromatography-mass spectrometry) in combination with GC-FID (gas chromatography with flame-ionization detection). The samples of PMMA were obtained by free-radical polymerization of MMA at room temperature (cold polymerized PMMA) and at 100 °C (hot polymerized PMMA), according to the manufacturer’s instructions. The MHE-GC-MS method consisted of ten successive extractions of MMA from the polymerized samples. According to the constructed calibration curve, the content of residual MMA in PMMA samples (mgMMA/gPMMA) was determined. Intramuscular implantation of sample materials was performed in experimental animals (rats) in order to demonstrate potential adverse effects of the unpolymerized residual reactants to the tissue in direct contact with polymeric implants. The content of residual monomer in cold polymerized PMMA was higher (15.75 mgMMA/gPMMA) in comparison to hot polymerized PMMA (10.96 mgMMA/gPMMA). The implanted samples of cold-polymerized acrylic resin showed intense inflammatory response of the surrounding tissue. According to the obtained results, hot polymerized PMMA is safer for use in dentistry.

Curcumin comes from the plant species Curcuma longa and shows numerous pharmacological activities. There are numerous curcumin formulations with gels or cyclodextrins in order to increase its solubility and bioavailability. This paper presents the formulation of complex of curcumin with 2-hydroxypropyl-β-cyclodextrin in a thermosensitive hydrogel, based on N-isopropylmethacrylamide and N-isopropylacrylamide with ethylene glycol dimethacrylate as a crosslinker. The product was characterized by chemical methods and also by FTIR, HPLC, DSC, SEM, XRD. The results show that synthesis was successfully done. With an increase in the quantity of crosslinker in the hydrogels, the starting release and the release rate of curcumin from the formulation of the complex with hydrogels decreases. The release rate of curcumin from the gel complex formulation is constant over time. It is possible to design a formulation that will release curcumin for more than 60 days. In order to determine the mechanism and kinetics of curcumin release, various mathematical models were applied by using the DDSolver package for Microsoft Excel application. The Korsmeyer-Peppas model best describes the release of curcumin from the gel formulation of the complex, while the values for the diffusion exponent (0.063–0.074) shows that mechanism of the release rate is based on diffusion.

The objectives of this study are the synthesis of thermosensitive poly(N-isopropylacrylamide-co-2-hydroxypropyl methacrylate), p(NiPAm-HPMet), hydrogels and the analysis of a drug-delivery system based on piroxicam, as a model drug, and synthesized hydrogels. A high pressure liquid chromatography method has been used in order to determine both qualitative and quantitative amounts of unreacted monomers and crosslinkers from polymerized hydrogels. Swelling kinetics and the order of a swelling process of the hydrogels have been analyzed at 10 and 40 °C. The copolymers’ thermal properties have been monitored by the differential scanning calorimetry (DSC) method. DSC termograms have shown that melting occurs in two temperature intervals (142.36–150.72 °C and 153.14–156.49 °C). A matrix system with incorporated piroxicam has been analyzed by using FTIR and SEM methods. Structural analysis has demonstrated that intermolecular non-covalent interactions have been built between side-groups of copolymer and loaded piroxicam. Morphology of p(NiPAm-HPMet) after drug incorporation indicates the piroxicam presence into the copolymer pores. Kinetic parameters of the piroxicam release from hydrogels at 37 °C and pH 7.4 indicate that the fluid transport mechanism corresponds to Fickian diffusion. As a result, formulation of thermosensitive p(NiPAm-HPMet) hydrogels with incorporated piroxicam could be of interest for further testing as a drug carrier for modulated and prolonged release, especially for topical administration.

The manuscript aimed to review the types of acrylate polymers used in dentistry, as well as their chemical, physical, mechanical, and biological properties. Regarding their consistency and purpose, dental acrylate polymers are divided into hard (brittle), which includes acrylates for the production of plate denture bases, obturator prostheses, epitheses and maxillofacial prostheses, their repairs and lining, and soft (flexible), which are used for lining denture bases in special indications. Concerning the composition and method of polymerization initiation, polymers for the production of denture bases are divided into four types: heat-, cold-, light-, and microwave-polymerized. CAD/CAM acrylate dentures are made from factory blocks of dental acrylates and show optimal mechanical and physical properties, undoubtedly better monomer polymerization and thus biocompatibility, and stability of the shape and colour of the base and dentures. Regardless of the number of advantages that these polymers have to offer, they also exhibit certain disadvantages. Technological development enables the enhancement of all acrylate properties to respond better to the demands of the profession. Special attention should be paid to improving the biological characteristics of acrylate polymers, due to reported adverse reactions of patients and dental staff to potentially toxic substances released during their preparation and use.

The surface quality of denture base resins allows for easy colonization by microorganisms including Candida albicans and Staphylococcus aureus, which cause major diseases of the oral cavity such as denture stomatitis. The widespread use of silver nanoparticles (AgNPs) in various fields of medicine has led to research of their possible application in dentistry, mostly in the prevention of bacterial adhesion, proliferation, and biofilm formation. The aim of the study was to synthesize cold and heat-curing denture base resins modified with AgNPs and AgCl, and evaluate the potential of the modified resins to reduce the growth of C. albicans and S.aureus. The produced material was characterized by Fourier transform infrared spectroscopy (FTIR). The antimicrobial potential of the modified material was demonstrated by the disc-diffusion method, microdilution method, and a modified microdilution method (i.e., disk-diffusion method in broth with viable counting). Spectroscopy confirmed the incorporation of biocidal materials into the structure of the denture base resins. The AgCl and AgNPs modified resins showed an antimicrobial effect. The significance of the study is in the potential therapeutic effects of the modified materials for prevention and threating staphylococci and candida in elderly patients, who are in most cases denture wearers and have a greater susceptibility to develop opportunistic infections. Modified denture base resins can significantly reduce the presence of infection at the point of contact between the denture and the mucous membrane of the prosthetic restoration. Biological tests of modified denture base resins will follow.

Conserving clean and safe freshwater is a global challenge, with nitrogen (N) and phosphorus (P) as frequent limiting factors affecting water quality due to eutrophication. This paper provides a critical overview of the spatiotemporal variability in both nutrient concentrations and their total mass ratio (TN:TP) in the canal network of the Hydro system Danube–Tisza–Danube at 21 measuring locations monitored by the Environmental Protection Agency of the Republic of Serbia over a length of almost 1000 km, collected once a month during the last decade. A spatiotemporal variation in nutrient concentrations in the tested surface water samples was confirmed by correlations and cluster analyses. The highest TN concentrations were found in winter and early spring (non-vegetation season), and the highest TP concentrations in the middle of the year (vegetation season). The TN:TP mass ratio as an indicator of the eutrophication pointed out N and P co-limitation (TN:TP 8–24) in 64% of samples, N limitation (TN:TP < 8) was detected in 27% and P limitation (TN:TP > 24) in the remaining 9% of water samples. Such observations indicate slow-flowing, lowland water courses exposed to the effects of non-point and point contamination sources as nutrient runoff from the surrounding farmlands and/or urban and industrial zones, but further investigation is needed for clarification. These results are an important starting point for reducing N and P runoff loads and controlling source pollution to improve water quality and underpin recovery from eutrophication in the studied watershed.

The aim of this study is to investigate the possibility of using electrospun polylactide (PLA) fibers as a carrier of the phytoestrogen biochanin A. Polylactide fibers were prepared with different contents of biochanin A by using an electrospinning method at specific process parameters. The obtained electrospun polylactide fibers, as carriers of biochanin A, were characterized by means of different methods. The presented results showed that the mechanical properties of PLA have not changed significantly in the presence of biochanin A. Scanning electron microscopy showed that the fine fiber structure is retained without visible deformations and biochanin A crystals on the surface of the fibres. The analysis by infrared spectroscopy showed that there are no strong interactions between polylactide and biochanin A molecules, which is a good prerequisite for the diffusion release of biochanin A from PLA fibers.The release of biochanin A from PLA fibers in buffer solution pH 7.4 at 37 °C was monitored by applying the HPLC method. The rate and time of the release of biochanin A from PLA fibers is in correlation with the amount of the active ingredient in the matrix of the carrier and follows zero-order kinetics. PLA fibers with biochanin A exhibit concentration-dependent activity on proliferation and migration of L929 fibroblasts in direct culture system in vitro, and proved to be suitable for a potential formulation for use in wound healing.

Curcumin (1,7-bis-(4-hydroxy-3-methoxyphenyl)-hepta-1,6-diene-3,5-dione) is a natural lipophilic polyphenol that exhibits significant pharmacological effects in vitro and in vivo through various mechanisms of action. Numerous studies have identified and characterised the pharmacokinetic, pharmacodynamic, and clinical properties of curcumin. Curcumin has an anti-inflammatory, antioxidative, antinociceptive, antiparasitic, antimalarial effect, and it is used as a wound-healing agent. However, poor curcumin absorption in the small intestine, fast metabolism, and fast systemic elimination cause poor bioavailability of curcumin in human beings. In order to overcome these problems, a number of curcumin formulations have been developed. The aim of this paper is to provide an overview of recent research in biological and pharmaceutical aspects of curcumin, methods of sample preparation for its isolation (Soxhlet extraction, ultrasound extraction, pressurised fluid extraction, microwave extraction, enzyme-assisted aided extraction), analytical methods (FTIR, NIR, FT-Raman, UV-VIS, NMR, XRD, DSC, TLC, HPLC, HPTLC, LC-MS, UPLC/Q-TOF-MS) for identification and quantification of curcumin in different matrices, and different techniques for developing formulations. The optimal sample preparation and use of an appropriate analytical method will significantly improve the evaluation of formulations and the biological activity of curcumin.

The main goal of this study was to develop a liposome formulation with sulfanilamide and to investigate the liposomes impact on its release and stability to the UV-A/UV-B and UV-C irradiation. Liposome dispersions with incorporated sulfanilamide were prepared by thin-film hydration method and liposomes role to the sulfanilamide release was investigated by using a dialysis method. Comparatively, sulfanilamide in phosphate buffer solution was subject to release study as well to the UV irradiation providing for the possibilities of kinetics analysis. In vitro drug release study demonstrated that 20% of sulfanilamide was released from liposomes within 1 h that is approximately twice as slower as in the case of dissolved sulfanilamide in phosphate buffer solution. The kinetic release process can be described by Korsmeyer–Peppas model and according to the value of diffusion release exponent it can be concluded that drug release mechanism is based on the phenomenon of diffusion. The sulfanilamide degradation in phosphate buffer solution and liposomes is related to the formation of UV-induced degradation products that are identified by UHPLC/MS analysis as: sulfanilic acid, aniline and benzidine. The UV-induced sulfanilamide degradation in the phosphate buffer solution and liposome vesicles fits the first- order kinetic model. The degradation rate constants are dependent on the involved UV photons energy input as well as sulfanilamide microenvironment. Liposome microenvironment provides better irradiation sulfanilamide stability. The obtained results suggest that liposomes might be promising carriers for delayed sulfanilamide delivery and may serve as a basis for further research. Keywords: Sulfanilamide, Liposomes, Stability, Irradiation, Degradation, Release

The temperature- and pH-responsive poly(N-isopropylacrylamide-co-acrylic acid), p(NIPAM-co-AA), copolymer was synthesized by free radical polymerization and examined as a carrier for modified release of biochanin A. Biochanin A is a biologically active methoxylated isoflavone which exhibits estrogenic and other pharmacological activities. Due to its poor aqueous solubility and extensive first-pass metabolism, biochanin A has low bioavailability. The aim of this work was to incorporate biochanin A into the synthesized p(NIPAM-co-AA) copolymer and to examine its release at the body temperature and pH values that correspond to pH values of vaginal and rectal cavities. The amount of released biochanin A was monitored by the ultra-visible spectroscopy (UV-Vis) method. The structure of synthesized p(NIPAM-co-AA) copolymer and copolymer with incorporated biochanin A were characterized by using Fourier transform infrared spectroscopy (FTIR) and scanning electron microscopy (SEM) methods. The content of residual monomers in the synthesized copolymer was analyzed by using the high-pressure liquid chromatography (HPLC) method. The swelling behavior of p(NIPAM-co-AA) copolymer was monitored in relation to the temperature and pH values of the surrounding medium. For modelling the process of p(NIPAM-co-AA) copolymer swelling, the full three-level factorial design was applied.

In this study, poly(N-isopropylacrylamide-co-2-hydroxypropyl methacrylate) hydrogels were synthesized using free radical initiated copolymerization method. Four hydrogels with different cross-linker concentrations were prepared. Semi-crystalline, cross-linked copolymer networks were confirmed by FTIR, SEM and XRD analysis. Variation of swelling behaviour was monitored gravimetrically and thermo-responsiveness has been noticed. An application of synthesized thermo-responsive hydrogels as carriers for the modulated release of anti-inflammatory model drug was investigated. Moreover, naproxen loading into these hydrogels was also determined using FTIR, SEM and XRD techniques and release was analyzed using HPLC method at simulated physiological conditions. Swelling kinetic and mechanism of water transport, as well as diffusion of naproxen through the hydrogels were analyzed. Thus, the aim of this work was to study various compositions of obtained hydrogels and their possibility of application as a thermo-responsive carrier for prolonged naproxen release in order to evaluate as a potential candidate for drug carrier in future pharmaceutical applications.

Poly(N-isopropylmethacrylamide) (p(NiPMAm)) is one of the lesser known homopolymers that has significant potential for designing new “intelligent” materials. The aims of this work were the synthesis a series of cross-linked p(NiPMAm) hydrogels by the free radical polymerization method and the application of gamma-ray radiation for additional cross-linking. The synthesized p(NiPMAm) hydrogels were structurally characterized by Fourier transform infrared spectroscopy (FTIR) and scanning electron microscopy (SEM). The amount of unreacted monomers was analyzed using high pressure liquid chromatography (HPLC) to evaluate conversion of monomers into polymers. The swelling behavior was monitored in dependence of pH and temperature changes. The previous aim of gamma-ray radiation was the further the cross-linkage of the obtained hydrogel sample in the gelatinous, paste-like state, but the gamma-ray radiation caused decomposition. After absorbing irradiation doses, they transformed into the liquid phase. The results obtained by the gel permeation chromatography (GPC) method indicated that only oligomers and monomers were present in the irradiated liquid material, without molecules with a higher average molar mass, i.e., that the decomposition of the hydrogels occurred. Additionally, the irradiated liquid material was analyzed using the static headspace gas chromatography mass spectrometry (HSS-GC/MS) and gas chromatography/flame ionization detection (HSS-GC/FID) methods. The presence of unchanged initiator molecule and a dominant amount of four new molecules that were different from homopolymers and the reactant (monomer and cross-linker) were determined.

The antioxidant activity ofwater, ethanol and methanol Hieracium pilosella L.extracts is reported. The antioxidative activity was tested by spectrophotometrically measuring their ability to scavenge a stable DPPH· free radical and a reactive hydroxyl radical trapped by DMPO during the Fenton reaction, using the ESR spectroscopy. Total phenolic content and total flavonoid content were evaluated according to the Folin-Ciocalteu procedure, and a colorimetric method, respectively. A HPLC method was used for identification of some phenolic compounds (chlorogenic acid, apigenin-7-O-glucoside and umbelliferone). The antioxidant activity of the investigated extracts slightly differs depending on the solvent used. The concentration of 0.30 mg/mL of water, ethanol and methanol extract is less effective in scavenging hydroxyl radicals (56.35, 58.73 and 54.35%, respectively) in comparison with the DPPH· radical scavenging activity (around 95% for all extracts). The high contents of total phenolic compounds (239.59–244.16 mg GAE/g of dry extract) and total flavonoids (79.13–82.18 mg RE/g of dry extract) indicated that these compounds contribute to the antioxidative activity.

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Nowadays, Serbia is not at a satisfactory level of sustainability due to the well known events that occurred within the past two decades. According to the European Commission, environmental protection is an area in whichSerbiawill have to give its maximum effort to fully meet European standards and the requirements of sustainable development in the future. Poor water quality in some parts of the country, undeveloped systems for waste collection and recycling, illegal dumps, and industrial pollution are some of the environmental problems affecting the Republic of Serbia. These findings encouraged the authors of the paper to focus on the environmental problems as a dimension of education for sustainable development in Serbian higher education. Regulatory frameworks of higher education and education for sustainable development in theRepublicofSerbiaare presented in the first part of the paper. The second part deals with observations on current staff development within professional education centres, where their abilities to work in the field of environmental protection are discussed. In the third part, an analysis of an autonomous and integrative approach to the environmental safety education is done, and the need and importance of greening higher education curriculum, as the new paradigm in the educational system, is emphasized. In this regard, an analysis of present ecological ideas and content in the syllabus of English language, which is one of the most common courses at Serbian faculties, and which is particularly important in response to the challenges of globalization, knowledge flow, international scientific research and mobility, is performed. Finally, as part of the authors’ concluding remarks, improvements related to the period before the reform of higher education and adoption of a national strategy for sustainable development, are presented. Also, their basic weaknesses and difficulties are described. New directions of the education for environmental protection in higher education, as well as the importance of training higher education lecturers in this area, are shown.

The objects of this investigation were the comparative kinetic analysis of the NiO and NiCl2 reduction by hydrogen during an induction period and elimination of the calcination during the synthesis of Ni/Al2O3 catalysts. The effect of temperature and time on NiO and NiCl2 reduction degrees was studied. Avrami I equation was selected as the most favorable kinetic model and used to determine activation energy of the NiO and NiCl2 reduction for the investigated temperature range (623–923 K) and time intervals (1–5 minutes). The investigation enabled reaching conclusions about the reaction ability and rate of the reduction processes. Afterward, Ni/Al2O3 catalysts were obtained by using oxide and chloride precursor for Ni. The catalysts were supported on alumina-based foam and prepared via aerosol route. Properties of the samples before and after low-temperature hydrogen reduction (633 K) were compared. Obtained results indicated that the synthesis of Ni/Al2O3 catalysts can be more efficient if chloride precursor for Ni is directly reduced by hydrogen during the synthesis process, without the calcination step. In addition, Ni-Pd/Al2O3 catalysts with different metal content were prepared by using chloride precursors. Lower reduction temperature was utilized and the chlorides were almost completely reduced at 533 K.

The transformation of the synthesized allicin, using conventional method, the influence of ultrasound and microwaves, in different organic solvents (acetonitrile, acetone, methanol, and chloroform), at various temperatures (room temperature, 45∘C, and 55∘C) was investigated. Allicin degradation kinetic was monitored by HPLC. Allicin transformation under the effect of microwaves is faster than transformations performed under the influence of ultrasound or by conventional method. Increase of the temperature accelerates allicin transformation. Pharmacologically active compounds of (E)-ajoene, (Z)-ajoene, 3-vinyl-4H-1,2-dithiin, 2-vinyl-4H-1,3-dithiin, and diallyl disulfide were isolated from the mixture of transformation products of allicin under the influence of microwaves in methanol at 55∘C, which is according to kinetic parameters (highest values of the order of reaction and the lowest activation energy) the optimal method.

Water is one of the key ecological factors that has a great impact to development and productivity of lowland species such as Quercus robur. This paper deals with water regime influence to site conditions of these species and how actually changeable soil moisture affects Q. robur. Studied area includes a protective embankment built on the river bank in order to eliminate flooding effect, which means that all needs for water these associations provide from rainfalls and groundwater. Water regime was monitored during two critical years (extremely dry and extremely wet) on four soil types – Planosol, Fluvisol and Gleysol that belong to hydromorphic (three experimental plots) and Chernozem which belongs to automorphic soils (three experimental plots), respectively. It was studied the distribution of rainfalls and groundwater during the growing seasons and how it affects total and available water amount in the soil. The main focus should be given to available water, because it is located in capillary pores and plants can utilize it. Bearing in mind rainfalls makes just 15–20% of the total water amount in the soil it is much more significant to evaluate its proportion in available water. Based on obtained results, we can deduce that much more suitable site conditions for Q. robur are present on hydromorphic soils due to much greater proportion of groundwater. [ABSTRACT FROM AUTHOR]

In the spacious inundation area on the left bank of the lower course of the Sava River in Serbia, there is an abandoned meander Special Nature Reserve, "Obedska bara", which represents a very important floodplain in this part of Europe. This area is characterized by an exceptional wealth of biodiversity with a significant presence of rare and endangered species of national and international importance. Hydrological conditions in the mentioned area were analyzed from the aspect of surface water movement in nature and conditions altered by human factors (after the construction of the road network, canals, etc.). The movement of surface water, i.e., the filling and emptying of the investigated area, parallel to the water level of the Sava River, is shown using a digital terrain model. Our simulation of the change in surface water level within the studied area included the display of underwater areas, both with the formation of a flood wave (i.e., increasing water level of the Sava) and with the outflow of water from the pond when the water level in the Sava was reduced in both scenarios (natural and conditions altered by human factors). GIS and terrain digitalization were used for geospatial and hydrological analyses and, based on this, maps that display endangered areas could be made. The obtained results show that the largest human impact was recorded at the water level of the Sava River 74 m above sea level. The aforementioned water regime changes were shown to negatively affect dominant vegetation, such as pedunculate oak and ash. [ABSTRACT FROM AUTHOR]