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Animal models in bicompatibility assessments of implants in soft and hard tissues
No full textThe ethical dilemmas of using animals as in vivo models in preclinical and clinical examinations have been increasingly present in recent decades. Small laboratory animals (rats, rabbits) will continue to be used because they are cost-effective and permit the formation of statistically testable cohort groups; a task that, for financial, maintenance and care reasons, is almost prohibitive for larger animals. Technological advances in the production of new biomaterials for clinical use are enormous, but screening tests and methods used to assess biocompatibility lag behind these advances. The assessment of biological responses is slow and based on millennial recovery mechanisms in eukaryotic organisms. Therefore, the goal of researchers in this field is to re-evaluate old methods of biocompatibility assessment and introduce new methods of evaluation, especially for in vivo testing. In that sense, a revision of the ISO standards was planned and conducted in 2017, which insisted on cytotoxicity testing in cell lines and produced concrete proposals on how biocompatibility should be quantified. In vivo biocompatibility evaluation of biomaterials used for soft tissue recovery commonly utilises rats. Rabbits are recommended for implants used for hard tissues, because of the rabbit’s size, the possibility of implanting the biomaterials on a larger bone surface, and because of the peculiarities of rabbit bone tissue that favours rapid recovery after bone defects and enables easy reading of the result
Thermal analysis and phase changes of mechanochemically activated sodium carbonate
No full textSodium carbonate is a well-known material for being used as a good sorbent of carbon dioxide from the atmosphere, and as such has gained increasing importance in environmental protection. In order to enhance its sorption ability, mechanochemical activation of sodium carbonate was carried out in this study while the occurred changes after the activation and the relaxation time in a controlled environment were monitored. Activation was performed in a vibro-mill from 1 to 28 min. Based on the results of specific surface area, obtained by BET, the samples activated for 2 and 7 min were chosen and placed in a moist carbon dioxide atmosphere for 96 h, a period called the relaxation time. Differential thermal and thermogravimetric analyses were applied with the aim of determining the changes that occurred on the activated samples during the relaxation period. The decomposition temperature change of activated Na2CO3 samples, as well as mass loss and conversion level of Na2CO3 to NaHCO3 were monitored depending on activation and relaxation time periods. The conversion reactions of sodium carbonate to sodium bicarbonate under the specified environment of carbon dioxide and moisture were also studied, and the thermodynamic data such are changes in enthalpy, entropy, and Gibbs energy at the temperature range of 0-160 degrees C are given
Elektroforetski taložene kompozitne prevlake kao nosaci lekova / Electrophoretically deposited composite coatings as drug carriers
No full textMetoda elektroforetskog taloženja (EPD)se koristi za sintezu biokompatibilnih
kompozitnih materijala za medicinsku primenu kao antibakterijske prevlake za koštane
implantate. Taloženjem pri konstantnom naponu je uspešno dobijena kompozitna prevlaka
hidroksiapatit/hitozan/poli(vinilalkohol) (HAP/CS/PVA) koja sadrži gentamicin (Gent).
Bioaktivnost prevlake je dokazana formiranjem novonastalog apatitnog sloja u simuliranoj
telesnoj tecnosti i karakterisana primenom skenirajuce elektronske mikroskopije (SEM) I
infracrvene spektroskopije sa Furijeovom transformacijom (FTIR). Sposobnost
oseointegracije dalje je potvr ena merenjem aktivnosti alkalne fosfataze (ALP), što
ukazuje na povoljna oseopromotivna svojstva taloženih prevlaka. Kada su testirane
humane i mišje fibroblastne celijske linije (MRC-5 i L929), kompozitne prevlake nisu
pokazale citotoksicni efekatThe electrophoretic deposition (EPD) method isused for the synthesis of biocompatible
composite materials for medical use as antibacterial coatings for bone implants. Deposition
at the constant voltage yielded composite coating hydroxyapatite/chitosan/poly(vinyl
alcohol)(HAP/CS/PVA) loaded with gentamicin (Gent). Bioactivity of the coating was
proved by a newly formed apatite layer in simulated body fluid and characterized
usingscanning electron microscopy (SEM) and Fourier transform infrared spectroscopy
(FTIR). The osseointegration ability was validated by measuring the alkaline phosphatase
activity (ALP) indicating the favorable osseopromotive properties of deposited coatings.
When tested against human and mice fibroblast cells lines (MRC-5 and L929), composite
coatings did not exhibit cytotoxic effect
The analysis of the crystal growth process of the lithium germanium phosphate glass
No full textThe crystal growth rate of lithium germanium-phosphate glass was studied. The glasses have been homogenized using the previously established temperature-time conditions, which make it possible to remove a volatile substances from the glass melt. The AAS was used to determine the chemical content of obtained glass, the differential thermal analysis (DTA), and scanning electron microscope (SEM) were used to reveal the isothermal process of crystal growth, respectively. It has been found that the experimental determined crystal growth rate has a tendency toward of exponentially increase with an increase the temperature
Application of nano–MnO2 modified lignin – based adsorbent for removal of dichromate ions and diclofenac from water
No full textThe aim of this paper is to investigate the application of modified lignin-based adsorbent for
successful removal of dichromate ions and sodium diclofenac (DCF) from aqueous solutions by
adsorption. Modification of lignin-based adsorbent (LBA) was performed by inverse suspension
copolymerization with branched poly (ethylene-imine) using epichlorohydrin as a crosslinker. After
that, the functionalization of LBA was performed by chemical binding of amino modified nanoparticles
of manganese (IV) oxide, in order to improve the adsorption properties. Characterization of
LBA-MnO2 microspheres was performed using FT-IR spectrometer, Scanning electron microscopy,
BET/BJH analysis. The adsorption process was performed in a batch adsorption system. The results
were obtained with the help of kinetic and corresponding equilibrium adsorption isotherms. The
maximum adsorption capacity for the removal of Cr2O7
2- ions and DCF was obtained using the
Langmuir model and amounts to 88.4 mg g-1 and 52.8 mg g-1 at 45 °C, respectively. Adsorption
kinetics was described using a second-order pseudo model. Based on thermodynamic parameters, it
was concluded that the adsorption process is an endothermic and spontaneous. Based on the obtained
results, LBA-MnO2 material possess very good adsorption properties
Identifikacija metoda za separaciju i karakterizaciju nanoplastike iz vodenih sredina / Identification of methods for separation and characterisation of nanoplastic from aquatic environments
No full textZagađenje vodenih resursa mikro- i nano-plastikom je prepoznato kao globalni problem. Trenutno ne postoje dostupne specifične metode za identifikaciju, karakterizaciju i kvantifikaciju nanoplastike u vodenim sredinama. Mnoge od metodologija razvijenih za analizu mikroplastike ne mogu se direktno primeniti na nanoplastiku, dok konvencionalne
metode karakterizacije nanoplastike obično izoluju i proučavaju pojedinačne nanočestice, što može biti naporan i dugotrajan proces. Korišćenjem mikroskopskih tehnika u kombinaciji sa spektroskopijom, moguće je ubrzati proces analize, ispitati morfologiju i veličinu čestica i istovremeno identifikovati hemiju. Pošto nanoplastika nastala degradacijom mikroplastike
ima drugačija svojstva od sintetisanih nanočestica plastike, neophodno je kreirati nove analitičke i mikroskopske tehnike koje će pomoći da se bolje razume ozbiljnost problema nanoplastike. Ovaj rad ima za cilj da identifikuje metode koje bi mogle da se primene za odvajanje i karakterizaciju nanoplastike iz vodenih sredina.Pollution of water resources with micro- and nanoplastics is recognized as a global problem. Currently, there are no specific methods available for the identification, characterization and quantification of nanoplastics in aquatic environments. Many of the methodologies developed for the analysis of microplastics cannot be directly applied to nanoplastics, while conventional nanoplastic characterization methods usually isolate and study individual nanoparticles, which can be a laborious and time-consuming process. By using microscopic techniques combined with spectroscopy, it is possible to speed up the analysis process, examine the morphology and size of the particle and identify the chemistry at the same time. Since nanoplastics created by the degradation of microplastics have
different properties than synthesized plastic nanoparticles, it is necessary to create new analytical and microscopic techniques that will help to better understand the seriousness of the nanoplastics problem. This work aims to identify methods that could be applied for the separation and characterization of nanoplastics from aquatic environments
Possibility of obtaining magnesium titanate by mechanochemical process in a high-energy vibro mill
No full textIn order to investigate the possibility of obtaining magnesium titanate, oxides of magnesium
and titanium were mechanochemically activated. Mechanical activation was performed for
1000 min in a high-energy vibro mill (engine power is 0.8 kV). The optimal amount of
powder activated in the mill is 50-100 g, so according to the stoichiometric calculation, the
composition of the starting mixture was 20.2 g (0.5 mol) MgO and 39.9 g (0.5). mol) TiO2.
X-ray diffraction analysis of samples taken from the reaction system was performed after 60,
180, 330 and 1000 min of mechanical activation. Atomic absorption spectrophotometry was
used to analyze the current chemical composition of the system, depending on the time of
activation. Based on the results of X - ray diffraction analysis, it can be concluded that the
greatest changes in the system occurred at the very beginning of mechanical activation due to
disruption of the crystal structure of the initial components. X-ray diffraction analysis of the
sample after 1000 min of activation showed complete amorphization of the mixture, but no
diffraction maxima characteristic of magnesium titanate was identified. Therefore, the
mechanical activation experiments were stopped. The fact is that the invested energy was not
enough to overcome the energy barrier for the formation of a new chemical compound -
magnesium titanate. The inability to synthesize magnesium titanate is explained by the low
negative Gibbs energy value of -25.8 kJ / mol (despite the theoretical possibility that the
reaction will occur), as well as the amount of mechanical energy that entered the system
during activation that is insufficient to obtain the reaction product. Although the synthesis of
MgTiO3 has not been achieved, significant results have been obtained that identify models for
further research into the possibility of mechanochemical reactions of alkaline earth metals and
titanium dioxide
Management of new technologies accompanying the development of information technologies in modern society
No full textKlasična promena informacionih tehnologija i stanja tehnike u procesima učenja i nastave je
pokazala da se iskorištava samo deo potencijala koji trenutno postoji u obrazovnim tehnologijama. Sistem
unapređenja postupka i implementacije učenja kao primarne lestvice ne dostiže potrebe savremenog napretka
i potreba koje se nameću stalnom eksponencijalnom evolucijom digitalnih tehnologija. Nove tehnologije
zahtevaju konstantno praćenje inovacija i praktično trenutnu transformaciju koja ispunjava ne samo
primenu novih znanja, već i potrebu da se utiče na sve sfere internog i eksternog životnog prostora. Nove
tehnologije moraju ispuniti sve ozbiljnije zahteve postavljene na višestepenom nivou, počevši od nabavke
sirovina do konačnog proizvoda koji dolazi do krajnjeg korisnika. Digitalizacija sistema, posebno primena
najnovijih informacionih tehnologija, zahteva trenutnu fleksibilnost i najviši nivo znanja.
Prevelika brzina razvoja novih informacionih tehnologija ne ostavlja mogućnost kvalitetne
implementacije. Pokazalo se da malo tehničkih inovacija u obrazovnom okruženju postiže adekvatan nivo
zrelosti, što neminovno dovodi do toga da većina njih nestaje u ranim fazama. Nedovoljan nivo
sistematizacije je posledica prevelike fascinacije koju izazivaju nove prakse, što na ciljnom delu ne ispunjava
očekivanja i dovodi do toga da njihova novost brzo nestane.
U hemijskoj industriji koja zahteva velika ulaganja u nove tehnologije prerade polaznih sirovina ovo
moze da predstavlja veliki problem. Razvoj novih informacionih tehnologija zahteva sve složenije sisteme
obrade i tehlološku strukturu koja je u stanju da prati ovaj razvoj. To dovodi do akceleracije znanja,
hiperprodukcije podataka i velike mogućnosti greške, što kao rezultat ima višestruke posledice. Suviše kratko
vreme ispitivanja i pokušaj primene jeftinijih produkata kao posledicu ima ili urušavanje sistema (jer nisu u
stanju da adekvatno prate zahteve nove informacione tehnologije) ili usled produkcije novih tehnologija
ostavlja veliku količinu materijala koji zahteva poseban tretman koji će zaostali i neiskorišćeni produkt
adekvatno reciklirati. Poseban osvrt je neophodan na završnom koraku primene novih informacionih
tehnologija, i to sa više aspekata: konačnog broja korisnika, finansijsku isplatljivost i posledice koje neminovno prate svaki razvoj
Sustainable development in a multiflicted solution environmental pollution
No full textWe are witnessing increasingly rapid and pronounced climate changes caused not only by natural processes, but also by increasing environmental pollution, which is a direct consequence of human activity. Population growth as well as technological and economic progress have a negative impact on the environment, and in recent decades, sustainable development and water security have been imposed as inevitable in solving the water-food-energy relationship. Water safety is the primary task in the project to mitigate the impact of environmental pollution at all world levels of structures. In 2015, the United Nations, with its 193 members, revised the agenda planned for 2030, which consists of 17 goals that are primary in the future, including social inclusion, environmental sustainability, justice, peace, economic development, good governance and partnership. One of the main goals of sustainable development is the central focus, and it refers to clean water and sanitation. This paper provides an overview of some global trends in wastewater treatment in relation to domestic methods of mine water purification. In the continuation of the research, the goal of the work was the valorization of man-made mineral raw materials (secondary sulfur and fly ash), which creates an environmentally acceptable and useful material from the mentioned ecologically hazardous substances, mass applicable primarily in construction, but also elsewhere. In addition, the project is focused on the removal of heavy metals from acid mine wastewater using pelletized fly ash as a sorbent that will be further used for the synthesis of sulfur concrete. The production of sulfur concrete implies the use of secondary sulfur from oil refining as a substitute for Portland cement binder in conventional concrete, which achieves a significant environmental and economic benefit.
The project includes several aspects useful in Europe and the world, such as obtaining new materials and using waste resources, which has a very important impact on environmental protection, as well as an important economic aspect. Since these fields are relatively young, their further development and application of the obtained results in the industry is expected in the future
Eco-friendly elderberry based sorbent for removing pb2+ ions from aqueous solutions
No full textElderberry (Sambucus nigra) pith was modified with polyethyleneimine (PEI) in order to improve the adsorption properties. Characterization of both dried Sambucus nigra pith (DSNP) and amino modification of elderberry pith with branched PEI (PEI/DSNP) was performed by: Fourier-transform infrared spectroscopy (FTIR), optical microscopy, and porosity determination. The amine and ester number, as well as acid value, were determined on DSNP and PEI/DSNP samples using standard volumetric methods. The samples were used as adsorbents for Pb2+ ions from an aqueous solution in a batch system. The obtained results were fitted using suitable equilibrium isotherm and kinetic models. The maximum adsorption capacity for Pb2+ ions on DSNP and aminated sample, obtained using Langmuir adsorption isotherm at 298 K, are 18.9 and 47.8 mg g(-1), respectively. Based on the kinetic studies, the adsorption process follows the pseudo second-order model. Thermodynamic parameters showed that the adsorption process is endothermic and spontaneous. In general, the overall adsorption process was improved by modifying starting material with branched PEI modifier by introducing large numbers of amino functionalities having high affinity to cations