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Lanthanum-doped phosphate glass for biomedical application
No full textGlass-ceramic with the composition 42P2O5·40CaO·La2O3·10Na2O·3TiO2 (mol %) was obtained by standard melt-quenching method. The crystallization and sintering behavior of glass have been studied by using DTA and XRD methods. The sintered phosphate glass-ceramic containing bioactive β-CaP2O6, α-Ca3(PO4)2 and β-Ca3(PO4)2 phases was successfully prepared
A review of the Pb-Zn-Cu-Ag-Bi-W polymetallic ore from the Rudnik orefield, Central Serbia
No full textThe Rudnik orefield is one of the well-known skarn-replacement and
high-temperature hydrothermal Pb-Zn-Cu-Ag-Bi-W polymetallic sulfide
deposits, and is a part of the Šumadija Metallogenic District, Serbia. It
comprises ore bodies grouped into several major ore zones. The
pseudostratified and platelike ore bodies have relatively high content of
valuable metals. The average content varies in wide ranges: Pb (0.94-5.66
wt%), Zn (0.49-4.49 wt%), Cu (0.08-2.18 wt%), Ag (50-297 ppm), Bi (~100-150
ppm), and Cd (~100-150 ppm). Generally, a complex mineral association has
been determined. Iron sulfides, arsenopyrite, chalcopyrite, sphalerite,
galena and sulfosalts are abundant minerals in the ore. Carrier minerals of
Bi and Ag are Bi-sulfosalts, such as galenobismutite, cosalite, Ag-bearing
aschamalmite, vikingite, schirmerite and gustavite. Copper, Ag and Pb-Sb
sulfosalts have been found only locally. Complex Ni-minerals (sulfides,
arsenides and sulfoarsenidеs) with Fe, Co and Ag were formed under to the
influence of present serpentine rocks and their yield of Ni, Co and Cr in
the hydrothermal ore-bearing solutions. Significant scheelite
mineralizations have been found in the Nova Jama, Gušavi Potok and Azna ore
zones. The presence of Bi-sulfosalts and argentopentlandite suggests
formation temperatures higher than 350, and lower than 445°C, respectively.
Therefore, the mineralization was formed in the temperature range 350 to
400°C. The continuity of pyrite, pyrrhotite and siderite colloform bands in
relic aggregates shows frequent changes of fS2 and fO2 in hydrothermal
solutions. Isotopic composition of sulfur also confirms that the source of
the ore-bearing fluids was magmatic. In addition, the enrichment of Bi and
Ag indicates a magmatic origin. The appearance of Biminerals represents a
significant genetic indicator for detection of increased Ag concentrations
within the ore mineralizations. Typical gangue minerals are quartz,
silicates, carbonates, oxides and different oxy-hydroxides. Special
attention is given to the paragenetic relationships and the genetic
significance of mineral associations as indicators of ore-forming conditions
Non-Isothermal Crystallization of Lithium Germanophosphate Glass Studied by Different Kinetic Methods
No full textCrystallization kinetics of 22.5Li(2)O center dot 10Al(2)O(3)center dot 30GeO(2)center dot 37.5P(2)O(5) (mol%) glass was studied under non-isothermal condition using the differential thermal analysis (DTA). The study was performed by using the first crystallization peak temperature (T-p1) which belongs to the precipitation of LiGe2(PO4)(3) phase in the glass. The activation energy of glass crystallization (E-a) was determined using different isokinetic methods. The dependence of E-a on the degree of glass-crystal transformation (alpha) was studied using model-free isoconversional linear integral KAS (Kissinger-Akahira-Sunose) and FWO (Flynn-Wall-Ozawa) methods. It was shown that the E-a varies with a and hence with temperature and consequently the glass/crystal transformation can be described as a complex process involving different mechanisms of nucleation and growth
Metal accumulation in populations of Calamagrostis epigejos (L.) Roth from diverse anthropogenically degraded sites (SE Europe, Serbia)
No full textHeavy metal accumulation is recognized as a very important global pollution problem in the last decades. Plant species have been recognized as natural bioindicators of environmental pollution, especially the amount of heavy metals in soils. Moreover, only a limited number of plant species can survive in highly contaminated soils. It is also known that metal accumulation can vary greatly among different populations of the same species. This study examines the chemical composition and accumulation potential of the expansive clonal grass Calamagrostis epigejos at five localities exposed to different levels of anthropogenic pressure. Considerable differences were observed between uptake, translocation, and accumulation of total and available heavy metals, such differences corresponding to soil physico-chemical characteristics and the level of site pollution. The results indicate that Calamagrostis epigejos uptakes a significant portion of the available fraction of heavy metals in the soil and stores it in the roots, thereby exhibiting a certain potential for metal phytostabilization
An optimized artificial neural network model for the prediction of rate of hazardous chemical and healthcare waste generation at the national level
No full textThis paper presents a development of general regression neural network (a form of artificial neural network) models for the prediction of annual quantities of hazardous chemical and healthcare waste at the national level. Hazardous waste is being generated from many different sources and therefore it is not possible to conduct accurate predictions of the total amount of hazardous waste using traditional methodologies. Since they represent about 40% of the total hazardous waste in the European Union, chemical and healthcare waste were specifically selected for this research. Broadly available social, economic, industrial and sustainability indicators were used as input variables and the optimal sets were selected using correlation analysis and sensitivity analysis. The obtained values of coefficients of determination for the final models were 0.999 for the prediction of chemical hazardous waste and 0.975 for the prediction of healthcare and biological hazardous waste. The predicting capabilities of the models for both types of waste are high, since there were no predictions with errors greater than 25%. Also, results of this research demonstrate that the human development index can replace gross domestic product and in this context even represent a better indicator of socio-economic conditions at the national level
Ibuprofen adsorption on a clinoptilolitic zeolitic tuff modified with cationic surfactant: direct method of composites preparation
No full textIntroduction
Interactions of cationic surfactants with natural zeolites have been extensively studied since they proved to be excellent adsorbents for various drug molecules contributing their functionality as drug carriers. Investigations related to nonsteroidal anti-inflammatory drugs (NSAIDs) are particularly interesting, since they are one of the most frequently used medications (Krajišnik et al., 2017). Sorption and release of ibuprofen (IBU) (a representative of NSAIDs; practically insoluble in water) by modified clinoptilolitic zeolitic tuff, in two step preparation procedure, was previously investigated (Krajišnik et al., 2015). According to this procedure, in the first step surfactant modified zeolites were prepared and then in the second step drug-modified zeolite composites were obtained by adsorption of IBU on modified zeolites.
The aim of this work was to carry out a study of direct method of drug-modified zeolite composites preparation and the influence of cationic surfactant:drug molar ratio on adsorption properties of clinoptilolitic zeolitic tuff.
Experimental Methods
In experiments, the initial clinoptilolitic zeolitic tuff from Zlatokop deposit (Serbia) (Krajišnik et al., 2011) was treated with solutions comprising surfactanthexadecyltrimethylammonium bromide (HB) in amounts equivalent to 100, 200 and 300% of its external cation exchange capacity (ECEC). In surfactant solutions (prepared at 40 C) IBU was solubilized at the same drug:surfactant molar ratio. The 10% aqueous suspensions were mixed on a high-speed disperser at 6000 rpm for 10 min. After mixing, the suspensions were filtered and the filtrates were collected for the drug assay by HPLC analysis. The obtained drug/modified zeolites composites, prepared by direct method, were denoted as ZHB-10 IBU/DM, ZHB-20 IBU/DM and ZHB-30 IBU/DM.
The average droplet size (Z-ave) and polydispersity index (PdI) in the starting drug/surfactant solutions were determined by photon correlation spectroscopy (PCS) using a ZetasizerNano ZS90 (Malvern Instruments, Malvern, UK). The zeta potentials of the starting zeolite and the prepared samples (drug/modified zeolites composites) were performed on the same apparatus. FT-IR spectra of the prepared samples and their individual components were recorded using a Nicolet iS50 spectrometer (Thermo Scientific, USA) in the range of 4000–400 cm−1 at a resolution of 2 cm−1.
Results and Discussion
In the starting drug/surfactant solutions, both IBU and HB were used at equimolar concentrations of 0.011 M, 0.022 M and 0.033 M for ZHB-10 IBU/DM, ZHB-20 IBU/DM and ZHB-30 IBU/DM, respectively. The HB concentration in all solutions was higher than its critical micelle concentration (cmc 0.92 mM at 20-25 °C). Instead of an intensive peak pattern associated with HB micelles, a group of very low intensity peaks was observed in a wider size range. The observed changes can be interpreted by disturbing the structure of the micelles under the conditions of agitation and temperature during the preparation of the starting solutions, and the formation of IBU complexes with individual HB molecules (Bunton et al., 1981), as well as their associates.The changes in zeta-potential of clinoptilolitic zeolitic tuff (ZVB) (Fig. 1a) were more pronounced for the samples with higher HB content compared with the sample ZHB-10 IBU/DM. Since the adsorbed amount of IBU on the prepared composites was lower for ZHB-10 IBU/DM ( 20 mg/g) and approximately the same for ZHB-20 IBU/DM and ZHB-30 IBU/DM ( 40 mg/g), increasing zeta potentials probably correspond to different surfactant coverage and organization at the mineral surface.
The bands in FT-IR spectrum of ZHB-30 IBU/DM (Fig. 1b) at 3618, 3420 and 1640 cm−1 are clinoptilolite characteristic bands related to acidic hydroxyls SiO(H)Al, hydrogen-bonding hydroxyl groups, and bending vibration of absorbed water, respectively (Korkuna et al., 2006). Compared to the FT-IR spectrum of ZVB the following bands were observed: the CH2 symmetric and asymmetric stretching vibrations of alkyl chain at 2919 and 2850 cm−1 and C–H scissoring vibrations of CH3–N+ moiety with peak at 1463 cm−1, which evidence the presence of HB (Sui et al., 2006). A weak band at 1384 cm−1 implies the presence of anionic form of adsorbed IBU (Krajišnik et al., 2015). The presented results of drug uptake by surfactant/zeolite composites revealed that drug adsorption from IBU/HB solutions could be successfully performed by the direct method of preparation, while cationic surfactant:drug molar ratio had influence on adsorbed amounts and organization of molecules on the zeolitic surface. Further investigations of pharmaceutical technical characteristics and drug release from the obtained composites would reveal their possible pharmaceutical application.
Acknowledgment
This work was realized within the framework of the projects TR 34031 and OI 172018 supported by the Ministry of Education, Science and Technological Development of Republic of Serbia
Elektrohemijski sintetizovani bioaktivni kompoziti za medicinske primene
No full textElektrohemijske metode su koris ćene za sintezu razlic itih kompozita namenjenih za aplikacije u medicini kao antibakterijske prevlake na koštanim titanskim implantatima ili kao visoko efikasni antimikrobni hidrogelovi za ubrzano zarastanje rana.
Prvi sintetisani materijal je kompozitna prevlaka hidroksiapatita (HAP) sa prirodnim polimerom hitozanom (CS) koja uključuje antibiotik gentamicin, dobijena metodom elektroforetskog taloz enja (EPD). EPD se izvodi pri konstantnom naponu na ploc icama c istog titana iz vodene suspenzije. Na ovaj nac in dobijena porozna homogena prevlaka ima poboljs anu mehanic ku c vrstoću i povoljne antibakterijske osobine. Prevlaka HAP/CS/Gent okarakterisana je difrakcijom X-zraka (XRD), infracrvenom spektroskopijom sa Furijeovom transformacijom (FT-IR) i skenirajućom elektronskom mikroskopijom (FE-SEM). Dobijeni rezultati potvrdili su formiranje nove kompozitne prevlake HAP/CS/Gent. Citotoksičnost prema dvema vrstama ćelijskih linija ispitana je koris ćenjem testa iskljuc ivanja tripan plave boje (DET) i MTT testa za procenu ćelijske metaboličke aktivnosti. Prevlaka sa antibiotikom (HAP/CS/Gent) pokazala je dobru antibakterijsku aktivnost protiv Staphylococcus aureus i Escherichia coli, dok je istovremeno zadržala nisku citotoksičnost, što ukazuje na visok potencijal za biomedicinske primene.
Drugi sintetisani materijal je biokompatibilni nanokompozitni hidrogel polivinil-alkohol/hitozan/grafen (PVA/CHI/Gr) sa nanočesticama srebra (AgNPs). AgNPs su dobijene in situ elektrohemijskom sintezom u matrici nabubrelih hidrogelova PVA/CHI/Gr. Korišćene su dve koncentracije CHI (0,1 mas.% and 0,5 mas.%), u cilju ispitivanja uticaja sadržaja CHI na svojstva nankompozitnih hidrogelova. Nanokompoziti Ag/PVA/CHI/Gr su dalje karakterisani metodom skenirajuće elektronske mikroskopije (SEM), Raman spektroskopije i rendgenske fotoelektronske spektroskopije (XPS). Otpuštanje srebra je praćeno tokom 28 dana, a dobijeni profili ukazuju na postepeno kontrolisano otpuštanje tokom ovog perioda. Antibakterijska aktivnost prema Staphylococcus aureus i Escherichia coli je potvrđena agar-difuzionim testom, dok je citotoksičnost ispitana direktnim testom isključenja sa bojom tripan-plavo (DET).Electrochemical methods were employed for synthesis of various composites intended for applications in medicine as antibacterial coatings on titanium bone implants or as highly efficient antimicrobial hydrogels for accelerated wound healing.
The first synthesized material is a composite coating of hydroxyapatite (HAP) with natural polymer chitosan (CS) which includes an antibiotic gentamicin, obtained by the method of electrophoretic deposition (EPD). EPD was carried out at the constant voltage on pure titanium plates from an aqueous suspension. Thus assembled porous homogenous coating would gain improved mechanical strength and favorable antibacterial properties. HAP/CS/Gent coating was characterized by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), and field emission scanning electron microscopy (FE-SEM). Obtained results confirmed the formation of a new composite coating HAP/CS/Gent. Cytotoxicity against two types of cell lines was investigated using trypan blue dye-exclusion test (DET) and MTT assay for assessing cell metabolic activity. The antibiotic loaded coating (HAP/CS/Gent) exhibited good antibacterial activity against Staphylococcus aureus and Escherichia coli, while preserving low cytotoxicity, indicating the high potential for biomedical applications.
The second synthesized material is biocompatible poly(vinyl alcohol)/chitosan/graphene (PVA/CHI/Gr) nanocomposite hydrogel loaded with silver nanoparticles (AgNPs). AgNPs were produced by in situ electrochemical synthesis in the pre-swollen PVA/CHI/Gr hydrogel matrix. Two concentrations of CHI (0.1 wt% and 0.5 wt%) were used in order to investigate the influence of CHI content on the properties of nanocomposite hydrogels. The Ag/PVA/CHI/Gr nanocomposites were further characterized by scanning electron microscopy (SEM), Raman spectroscopy and X-ray photoelectron spectroscopy (XPS). Silver release was monitored for 28 days and the obtained profiles indicate slow controlled release over chosen time period. Antibacterial activity against Staphylococcus aureus and Escherichia coli was confirmed by disc-diffusion tests, while low cytotoxicity was confirmed using trypan blue dye-exclusion test (DET)
Antibiotic loaded bioactive orthopedic implant coating
No full textA single-step electrophoretic deposition (EPD) process from aqueous suspension was used to
assess novel composite coating of hydroxyapatite (HAP) with natural polymer chitosan (CS)
and antibiotic, gentamicin (Gent). EPD was carried out at constant voltage on pure titanium
plates. In order to investigate the gentamicin influence on physico-chemical and biological
properties of composite coatings, detailed characterization was performed. For that purpose
X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), and fieldemission
scanning electron microscopy (FE-SEM) were used. Obtained results confirmed the
formation of a new composite HAP/CS/Gent coating. Potential application was examined
through biological assays. The gentamicin addition strongly improved the antibacterial
activity of HAP/CS/Gent coating that was confirmed by agar diffusion method and test in
suspension. Obtained results indicated more pronounced antibacterial effect against
Staphylococcus aureus compared to Escherichia coli. MTT and DET tests indicated low
cytotoxicity against MRC-5 and L929 tested cell lines, indicating good biocompatibility of
obtained composites. MRC-5 human cell line responded better in cytotoxicity testing,
pointing to encouraging results for potential application. The ability of biomineralization
promotion was noticed through the ALP assay. Therefore, HAP/CS/Gent coating can be
considered as perspective material for bone tissue engineering as hard tissue implant
Perspektive daljeg razvoja postrojenja za flotacijusku koncentraciju Pb-Zn rude rudnika-Grot A.D. (Blagodat)-Kriva Feja (Vranje)
No full textU ovom radu prikazani su rezulati rada Rudnika-Grot. Pre svega su prikazani stanje, tehnologija i način rada na rudi koja se u ovom trenutku eksploatiše i prerađuje.
U drugom delu rada je prikazana tehnološka inovacija iz 2017.kojom je izmenjena šema tehnološkog postupka u pogonu za flotirtanje olovo-cinkane rude Rudnika Grot.
U trećem delu rada prikazana su ispitivanja kojima treba da se proširi eksploataciono polje Rudnika-Grot, na ležište Kula, i da uvećaju rezeve rude za buduću eksploataciju. U ovom delu ispitivanja obavljena sui obimna fizičko-hemijska i mineraloška ispitivanja rude, kao i tehnološki opiti flotiranja u laboratorijskom obimu kojima su dobijeni komercijalni koncentrati olova i cinka
Minerageny of zeolite tuffs of Serbia
No full textLežišta naših zeolitskih tufova (Zlatokop, Igroš, Jablanica 1, Beočin, Toponica i Slanci) koja su ovde bila predmet detaljnih istraživanja, prostorno i genetski vezana su za vulkanske i vulkanoklastične stene marinskih sredina senonske i neogenske starosti i jezerske sedimente neogene starosti i nastala su kao produkt devitrifikacije vulkanskog stakla. Tokom laboratorijskih ispitivanja pri izradi ove doktorske disertacije, primenjene su sledeće analitičke metode: optička ispitivanja petrografskih preparata; rendgenska difrakcija praha (XRD); skenirajuća elektronska mikroskopija (SEM metoda); hemijska karakterizacija zeolitskih tufova u okviru koje je izvršeno određivanje hemijskog sastava i sadržaja teških metala i elemenata u tragovima, metodom atomsko apsorpcione spektroskopije (AAS); određivanje kapaciteta katjonske izmene-određivanje izmenjivih katjona Ca2+, Mg2+, Na+ i K+ i određivanje ukupnog kapaciteta katjonske izmene (KKI) i metode termičke karakterizacije– termogravimetrijska i diferencijalnotermička analiza (DTA/TG metoda). Navedene analitičke metode su omogućile realizaciju postavljenih ciljeva istraživanja, pri čemu je: – dat pregled geoloških karakteristika ležišta i pojava zeolitskih tufova na području Srbije; – definisana detaljna mineraloška i kristalohemijska karakterizacija zeolitskih tufova Srbije; – izvršena detaljna tehnološka karakterizacija naših zeolitskih tufova (XRD, DTA/TGA, SEM); – definisan genetski model obrazovanja zeolitskih tufova i utvrđene zakonitosti razmeštaja ležišta i pojava zeolitskih tufova Srbije i – navedene mogućnosti primene različitih tipova zeolita u različitim granama privredne delatnosti, uključujući prikaz dobijanja određenih proizvoda (u ITNMS-Beograd) na bazi zeolitskih minerala naših ležišta zeolitskih tufova i njihovu primenu u navedenim oblastima privrede...Our zeolite tuff deposits (Zlatokop, Igroš, Jablanica 1, Beočin, Toponica and Slanci), which were the subject of detaild research, spatially and genetically are connected to volcanic volcaniclastic rocks of marine environment of Senonian and Neogene age, as well as lake sediments of Neogene age. Zeolitic tuff deposits were formed as a product of devitrification of volcanic glass. During the laboratory research following analytical methods: thin sections petrography; X-Ray Diffraction (XRD); Scanning Electron Microscopy (SEM); chemical characterization (main elements, trace elements and heavy metal content) obtained by Atomic Absorption Spectroscopy (ААS); Cation Exchange Capacity of Ca2+, Mg2+, Na+ и K+ (CEC ); themal characterization – thermogravimetric and differentlial thermal analysis (DTA/TGA). Specified analytical methods enabled the realization of the set goals of the research. Namely: – Overview of geological characteristics of Serbian zeolitic tuff deposits ad occurrences; – Defined detailed mineralogical and crystallochemical characterization of Serbian zeolitic tuff deposits; – Obtained detail technological characterization of Serbian zeolitic tuff deposits (XRD, DTA/TGA, SEM); – Defined genetic model of formation of zeolitic tuffs and determined disposition of Serbian zeolitic tuff deposits and occurences; – Specified application possibilities of different zeolite types in various branches of economic activities, including a view of obtaining certain products (in ITNMS-Belgrade) on the basis of zeolite minerals obtained from our deposits, and their application in the stated areas of the economy