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Pr3+ doped fluorapatite nanoparticles obtained by co-precipitation method
No full textNanočestice apatita dopirane elementima retkih zemalja su intenzivno proučavane kao potencijalni luminiscentni materijali za obeležavanje ćelija i tkiva, u bioinženjeringu tkiva, za remodeliranje kostiju i posmatranje distribucije lekova [1-3]. Nanočestice Pr3+ dopiranih fluorapatita (Pr-FAP) sfernog oblika uspešno su sintetisane postupkom koprecipitacije i okarakterisane primenom XRD, FTIR, PL i SEM-EDX metoda. Emisija nanočestica fluorapatita (FAP) javlja se u ljubičastoj oblasti
vidljivog dela spektra, uz crveni pomak u oblast zelene boje kada je Pr3+ ugrađen u rešetku. MCR-ALS (Multivariate Curve Resolution-Alternating Least Squares) analiza fluorescentnog spektara i ab initio proračuni ukazuju da se joni Pr3+ nalaze u Pr-FAP rešetki na Ca2 (6h) položaju. Pretpostavljamo da je mehanizam zamene Ca2+ jona sa Pr3+ jonima praćen kompenzacijom naelektrisanja ugrađivanjem CO32- jona u strukturi ili
formiranjem šupljina na položajima jona metala. Dobijeni uzorci pokazali su mali stepen hemolize, a stepen hemolize se povećava sa smanjenjem veličine kristalita. Rezultati hemolize ukazuju da se ove sintetičke
nanočestice mogu potencijalno koristiti za dalja biomedicinska istraživanja, kao što su obeležavanje ćelija i tkiva, bioinženjering, za terapiju karcinoma i ispitivanje distribucije leka.The apatite nanoparticles doped with rear earth elements have been extensively studied as a potential luminescence inorganic material for cells and tissue labeling, bioimaging in tissue engineering and bone re-modelling, and for observing the distribution and drug delivery [1-3]. Sphere-like nanoparticles of Pr3+ doped fluorapatite (Pr-FAP) have been successfully
synthesized by co-precipitation method and characterized by XRD, FTIR, PL and SEM EDX methods. Emission of fluorapatite nanoparticles (FAP) occurs in violet region of visible part of spectrum, with red shift to green color region when Pr3+ is doped in lattice. MCR-ALS (Multivariate Curve Resolution-Alternating Least Squares) analyses of fluorescence spectra and ab initio calculation indicated that Pr3+ ions are located in Pr FAP lattice at Ca2 (6h) sites. We assume that the mechanism of substitution of Ca2+ with Pr3+ ion is accompanied with charge compensation by incorporation of CO32- ions in structure or by vacancies formation on metal ions position. The obtained samples showed a small degree of hemolysis, and degree of hemolysis
increases with decrease in crystallite size. The results of hemolysis suggest that the synthesized nanoparticles can be potentially used for further biomedical research, such as cells and tissue labeling, bioimaging, cancer therapy and drug delivery
Electrophoretically deposited bioactive hydroxyapatite/chitosan coatings loaded with gentamicin
No full textHydroxyapatite (HAP) is a widely used biochemical material, because it promotes
osteointegration, has outstanding biocompatibility and chemical composition similar to
natural bone. In order to improve the mechanical and antimicrobial properties of HAP,
biocompatible, natural polymer chitosan and antibiotic gentamicin were employed. The
obtained composite hydroxyapatite/chitosan/gentamicin (HAP/CS/Gent) was assembled
on pure Ti plates using the cathodic electrophoretic deposition process from an aqueous
suspension.
The aim was to produce a uniform bioactive coating with improved mechanical
strength and favorable antibacterial properties. HAP/CS/Gent coatings were
characterized by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR),
X-ray photoelectron spectroscopy (XPS), field emission scanning electron
microscopy (FE-SEM). Addition of the polymer significantly improved morphology, and
bioactivity of thus formed composite. HAP/CS/Gent composite coatings exhibited strong
antibacterial activity against Staphylococcus aureus and Escherichia coli
"Timok Scientific Tornado- TNT" - a model for science popularization and the development of competencies through cooperation with the stakeholders
No full textTimok Scientific Tornado – TNT” is a complex project that is being implemented for five years in
Eastern Serbia. The aim of project is to contribute the reform of the educational system by developing specific
extracurricular models and activities for popularization of natural and technical sciences, increase the
knowledge and motivation of students for further education in these areas, develop the skills and competencies
of students and teachers, raise environmental awareness, strengthen cooperation between schools and the
surrounding stakeholders. Project activities include realization of the Science Festival, the Night of the
Researchers and various scientific exhibitions. Due to the great success of previous events of such kind and the
constant increase in the number of participants and demonstrations it is expected that the programs of the TNT
will become part of the annual work plans of primary and secondary schools, and that all municipalities in
Eastern Serbia become participants in this program
New directions of the application of micronizing mineral raw materials
No full textThe paper aims to show the wide application of micronized products that arise after micronization milling. Fine-tinted-micronized materials such as alumosilicates, lycones, non-metallic mineral raw materials, thanks to their physical-mechanical, physical and chemical properties (density, color, shape, reflection index, conductivity, size and structure of micro particles, etc.) production of modern new materials. They can be used as fillers, coatings, for dusting, used in processing, pharmaceutical and other industrial branches, and they are irreplaceable in the production and processing of many definite products. Micronized mineral resources represent a significant potential in remedying the harmful effects of environmental pollution, but also one of the crucial factors in preventing this same pollution
The construction and ceramics industry waste gypsum valorization possibilities
No full textThe construction work and ceramic materials industry debris is an important source of waste that ends up unused and disposed on municipal solid waste landfills. Besides concrete and clay based materials, gypsum waste is one of the larger contributors to the building and industry byproducts production chain. The possibilities of waste gypsum revitalization and reutilization in the ceramic industry and civil engineering are investigated in this paper. The gypsum in its dihydrate form is used for moulds in the production of ceramic cast materials. The interest in recovering gypsum waste is increasing as the demand for sustainable production grows. Before secondary gypsum is reapplied, its properties and the recycling process have to be technically and environmentally evaluated. By recy- cling gypsum waste, natural gypsum deposits are being preserved. Furthermore, large percentage of this byproduct achieves its reutilization potential. In this con- text, this paper investigates physical properties, the chemical composition and the thermal behavior of the waste gypsum. The goal is to assess the feasibility of using waste gypsum and to evaluate the viability of the recycling process. The results indicate that the reutilization of gypsum waste might provide a viable substitute for clay in the ceramics industry. Reapplication of the revitalized secondary gypsum is approved from both economical and environmental aspect
The choice of high gradient magnetic separation processes for removal of Fe2O3 carriers from quartz raw material
No full textThis review article surveys the subject of choice of high gradient magnetic separation processes for removal of Fe2O3 carriers from quartz raw material by electromagnetic separator with magnetic field intensity of 1.4 T. The review is based on current experience of authors during research phase, as well as project development phase and initial operation of facilities in several locations. Quartz mineral raw material in those locations appeared as sandstone or as loose material. In addition to that, quartz raw material from those locations contained various impurities, i.e. Fe2O3 carriers. The choice of this process for Fe2O3 removal depended on mineralogical composition, shape and the content of minerals, and Fe2O3 removal rate after this process was from 29 to 65%. Magnetic separation is magnetic induction of 1.4 T. It is applied on commercial assortments which were previously subjected to washing and classification processes. It is always the assortment which has to have the lowest Fe2O3 content. The choice of, "dry" or, "wet" magnetic separation (with water flush) also depends on the fact whether this desired assortment is intended for market as dry or wet, as well as on the composition of magnetic impurities. In most cases, the process applied is the wet one
Adsorption of the mycotoxin zearalenone by clinoptilolite and phillipsite zeolites treated with cetylpyridinium surfactant
No full textIn this study, organozeolites were prepared by treatment of the natural zeolites (clinoptilolite and phillipsite) with cetylpyridinium chloride (CP) equivalent to 50 and 100% of their external cation exchange capacities (ECEC). Organoclinoptilolites (ZCPs) and organophillipsites (PCPs) were characterized by FTIR spectroscopy, thermal analysis, determination of the point of zero charge and zeta potential. Adsorption of zearalenone (ZEN) by ZCPs and PCPs at pH 3 and 7 was investigated. Results showed that adsorption of ZEN increases with increasing amounts of CP at the zeolitic surfaces for both ZCPs and PCPs but the adsorption mechanism was different. Adsorption of ZEN by ZCPs followed a linear type of isotherm at pH 3 and 7 while ZEN adsorption by PCPs showed non linear (Langmuir and Freundlich) type of isotherm at both pH values. Different interactions between the ZEN molecule (or ion) and ZCPs and PCPs occurred: partition (linear isotherms) and adsorption in addition to partition (non linear isotherms), respectively. For the highest level of organic phase at the zeolitic surfaces, the maximum adsorbed amount of ZEN was 5.73 mg/g for organoclinoptilolite and 6.86 mg/g for organophillipsite at pH 3. Slightly higher adsorption: 6.98 mg/g for organoclinoptilolite and 7.54 mg/g for organophillipsite was achieved at pH 7. The results confirmed that CP ions at both zeolitic surfaces are responsible for ZEN adsorption and that organophillipsites are as effective in ZEN adsorption as organoclinoptilolites
X-ray diffraction analysis of cold rolled strip from jewelry 585 gold alloy
No full textIspitivana legura zlata oznake 585, posmatrana u ovom radu je najčešće korišćena legura u juvelirskoj proizvodnji. Nedovoljno podataka, čak i danas, postoji oko proizvodnih postupaka legura zlata, uključujući režime topljenja, valjanja i termičke obrade. Strukture kompleksnih legura, kao što je ovde korišćena legura, su manje poznate ili izučavane. Principijelno, dijagram stanja sistema Au-Ag-Cu je poznat, kao (meta)stabilni dijagram. Ali posle relativno brzog hlađenja rastopa za vreme livenja obrazuju se polikristalna zrna, koja nisu nastala u ravnotežnim uslovima. Takav polikristalni materijal često se podvrgava valjanju radi dobijanja željenog oblika (polu)proizvoda. Ovi procesi, livenja i valjanja, pokazuju uticaj na konačnu strukturu, takođe i na osobine ovako tretirane legure. Strukturne promene kao i dobijene faze u procesima obrade legure zlata 585 još uvek nisu adekvatno ispitane. U ovom radu prikazani su neki rezultati izvršenih rendgenografskih ispitivanja nakon hladnog valjanja trake. Ispitivanja su izvršena na odlivcima dimenzija 4,5x50x50mm, koji su podvrgavani plastičnoj preradihladno valjanje do debljine trake od 1,5 mm, međufazno odžareni i završno izvaljani do debljine od 0,5mm, uz visinsku redukciju od 66,7%.Here is investigated an golden alloy 585 as one of widely used gold alloy in jewelry production. Insufficient data, even in nowadays, exist about the production schedule of gold alloys, including melting, rolling and heat treatment regimes. The structures of complex alloys, such as used golden alloy, are less known and/or investigated. Principally, the constitutional diagram of Au-Ag-Cu system is known, as a (meta)stable equilibrium diagram. But, after relatively fast cooling from liquid state during casting will be obtained polycrystalline grains, different from equilibrium conditions. Such polycrystalline material frequently undergoes to rolling for obtaining a desired shape of (semi)product. Those processes, casting and rolling, will show the influence on the final structure to be obtained, also on properties of such treated alloy. The structural changes and obtained phases in metal working processes of 585 gold alloy still are not well examined, so here is provided an XRD examination after heavy reduction at cold rolling of a strip. The castings were in the flat form in dimension of 4,5x50x50mm, than cold rolled to 1,5mm, intermediate annealed and finally cold rolled to thickness of 0,5mm with height reduction of 66,7%
Imobilisation of alkali treated apricot shells as a biosorbent for heavy metals removal
No full textIn this work, the design and usage of biosorbents made of apricot shells (Prunus armeniaca L.), Na-alginate and bentonite, for heavy metals removal from wastewaters, were investigated. The effect of particle size on the biosorption process, were investigate and the smallest fraction, was immobilized in Na-alginate. Immobilization had a positive effect on the biosorption process, but due to the inhomogeneity of the granules, bentonite was added as a binding agent. The result was increase of Cu(II) and Zn(II) removal up to 35% and Pb(II) up to 60. The composed granules were used for real effluent treatment. Obtained results indicated that this kind of composite biosorbent can be used in treatment of effluents contaminated with heavy metals pollution
Sphalerite passivation during the leaching sodium nitrate and sulphuric acid solution
No full textZinc is extracted from sphalerite and complex concentrates by pyrometallurgical or hydrometallurgical processes, whereby the hydrometallurgical processes
have received considerable attention in recent years. Thair application provide
better metal recoveries and reduced emission of gaseous and toxic agenses in the
environment. This paper studies the leaching process of the sphalerite with sodium
nitrate in sulphuric acid solution. Chemical reactions of leaching and their thermodynamic probabilities are predicted based on the calculated Gibbs energies and
analysis of E-pH diagrams. Thermodynamic analysis, experimental data, chemical,
XRD, TG/DTA, and SEM/EDX analyses for the phases present in both the complex
concentrate and leach residue were performed to determine the leaching process.
Elemental sulphur is the main solid product of reaction, and a minor amount of
sulphide sulphur is oxidized to sulphate during the leaching. It also indicates that
the sulphur precipitated at the particle surfaces, and slowed down the rate of the
leaching process