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Applications of the ArgusLab4/AScore protocol in the structure-based binding affinity prediction of various inhibitors of group-1 and group-2 influenza virus neuraminidases (NAs)
No full textUsing the crystal structures of inhibitors bound to either group-2 or group-1 neuraminidases (NAs), AScore/ShapeDock (GaDock) scoring was shown to identify the binding modes in agreement with the experiment for all inhibitors docked in their own NA/inhibitor crystal structures. To investigate the effect of small changes in protein structure on predicted binding modes, in a set of 132 docking experiments (11 inhibitors docked in 12 group-2 NA structures), AScore/ShapeDock (GaDock) identified the correct binding modes of 116 complexes. In a total of 88 docking experiments (8 inhibitors docked in 11 group-1 NA structures), AScore/ShapeDock predicted 80 binding modes correctly. Flexible AScore/ShapeDock docking, as quite reproducible, is suggested to be convenient for designing novel H5N1 inhibitors
Greenhouse gases with high value of global warming potential: GWP
No full textOd početka Industrijske Revolucije porast ljudske populacije i aktivnosti doveo je do iskorišćenja svih energetskih izvora sa posledicama emisije gasova sa efektom staklene bašte. Akumulacija ovih gasova u atmosferi je prouzrokovala promenu klime i oštećenje ozonskog omotača. Uticaj različitih GH (greenhouse) gasova se može opisati kroz promene u atmosferi i potencijala globalnog zagrevanja GWP. Ujedinjene Nacije su usvojile Kjoto protokol sa namerom kontrole globalnog zagrevanja i klimatskih promena. Srbija je ratifikovala Kjoto protokol 2007 godine, sa ciljem ne samo zaštite svoje životne sredine već i ekonomskog rasta. U radu su sagledani navedeni problemi, posledice i mogućnosti njihovog rešavanja. .Growing human population and human activity since beginning of industrial Revolution, lead to usage of all energy resources with consequence of emission of gasses with greenhouse effect and their accumulation in atmosphere, had cause climate change and ozone (loss) depletion. Effect of different greenhouses gases GH can be described with two scales: atmospheric life time and Global Warming potential GWP. For the purpose of controlling the global warming and climate changes United Nations has adopted Kyoto Protocol. Serbia ratified Kyoto Protocol in 2007, so that is chance not only for Environmental Protection of Serbia but also for economic growth. In this paper are introspected those problems their consequences and possibility for solving.
Ispitivanje mogućnosti dobijanja montmorilonita modifikovanog jonima bakra kao adsorbenta aflatoksina B1
No full textU ovom radu su dati rezultati ispitivanja mogućnosti dobijanja materijala za adsorpciju aflatoksina B1 modifikacijom minerala montmorilonita jonima bakra. Ispitivanja su rađena na bentonitskoj glini koja se eksploatiše u ležištu Sokolac kod Šipova u Republici Srpskoj. Rezultati pokazuju da stepen jonske izmene neorganskih katjona u montmorilonitu jonima bakra raste sa porastom polazne količine bakra u rastvoru. Za ispitivanja adsorpcije aflatoksina B1 na montmorilonitu modifikovanom jonima bakra je odabran proizvod sa sadržajem bakra 2.65%. Određeno je da montmorilonit, kao i montmorilonit modifikovan jonima bakra efikasno adsorbuju aflatoksin B1, pri različitim sadržajima čvrste faze u suspenziji, kao i na različitim pH. Pri sadržaju čvrste faze u supenziji 10 g/l, indeks adsorpcije aflatoksina B1 na montmorilonitu iznosi 100% na pH 3, 98% na pH 7 i 96% na pH 9. Na montmorilonitu modifikovanom jonima bakra, pri istom količini čvrste faze u suspenziji, dobijene su sledeće vrednosti indeksa adsorpcije aflatoksina B1: 98% na pH 3, 98% na pH 7 i 96% na pH 9. Sa smanjenjem količine čvrste faze u suspenziji (0.5 g/l), ne dolazi do smanjenja indeksa adsorpcije ovog toksina na oba adsorbenta. To znači da, jonska izmena neorganskih katjona u koncentratu montmorilonita sa jonima bakra nije dovela do smanjenja indeksa adsorpcije aflatoksina B1, kako na pH 3, tako i na pH 7 i 9. Zapaženo je i da adsorpcija aflatoksina B1 na oba adsorbenta ne zavisi od pH sredine.In this paper, the results of possibility for preparation of material for aflatoxin B1 adsorption, based on modification of montmorillonite with copper ions, re presented. The bentonite clay from Sokolac deposit (Šipovo, Bosnia) was used as the starting raw material. It was determined that ion exchange degree of inorganic cations in montmorillonite with copper ions increase with increasing the initial copper concentration in solution. The copper modified montmorillonite with 2.65% of copper was selected for aflatoxin B1 adsorption experiments. It was shown that montmorillonite, as well as the copper modified montmorillonite were efficient in adsorption of aflatoxin B1, at different amounts of solid phase in suspension, and at different pH values. Thus, at the amount of solid phase in suspension 10 g/l, aflatoxin B1 adsorption index for montmorillonite was 100% at pH 3, 98% at pH 7 and 96% at pH 9. For copper modified montmorillonite, at the same amount of solid phase the following aflatoxin B1 adsorption indexes were achieved: 98% at pH 3, 98% at pH 7 and 96% at pH 9. No differences in adsorption of this toxin by both montmorillonites with decreasing the amount of solid phase in suspension (0.5 g/l) were observed. That means that ion exchange of inorganic cations in montmorillonite with copper ions, did not cause any changes in aflatoxin B1 adsorption, at pH 3, as well as at pH 7 and 9. It was also noticed that adsorption of aflatoxin B1 by both adsorbents was not pH dependent
Effect of polymer powders application on thin-layer ceramic glues: Dry mortars
No full textU radu su data ispitivanja karakteristika tankoslojnih lepkova za keramiku. Ovi lepkovi su u potpunosti eliminisali klasičan način lepljena keramičkih pločica u debeloslojnom malteru. Ispitivana su dva lepka, pri čemu je jedan bio znatno kvalitetniji i sadržao je redispegujući polimerni prah čije je prisustvo znatno uticalo na poboljšanje niza karakteristika lepka saglasno novim EN 12004 normama. .This paper is concerned with investigation of thin-layer glues for ceramic. These glues have completely eliminated classic ones. Two different glues have been investigated. One of them had much better quality and contained polymer powder whose presence improves properties of glue in accordance with new EN 12004 standards.
Electrokinetic properties of apatite under flotation conditions
No full textU okviru ovog rada prikazani su rezultati merenja elektrokinetičkog potencijala apatita, u uslovima pod kojima se vrši flotiranje minerala apatita iz pulpe. Merenja su izvođena u unapred definisanom reagentnom režimu, vremenu kondicioniranja i sa pH vrednostima pri kojima su bili izvedeni opiti flotiranja. Takođe su izvršena merenja elektrokinetičkog potencijala (zeta potencijala) u kojima je ispitivan uticaj pojedinih jona na površinske osobine minerala apatita odnosno na elektrokinetički potencijal. Ovim merenjima je definisan način izmene površina apatita pri tačno određenim uslovima i unapred zadatim parametrima pulpe.Results of apatite electrokinetic potential under the flotation conditions from the pulp was measured and results are presented in this paper. Measurements are realized in predefined reagent regime, conditioning time and pH values like as during the flotation test. Also, measurements of electrokinetic potential (zeta potential) were done in order to investigate influence of partial ions on surface properties of apatite mineral i.e. on electrokinetic potential. Method of surface apatite modification upon exactly defined conditions and predefined pulp parameters is determined by these measurements
T-2 toxin adsorption by hectorite
No full textU ovom radu su prikazani rezultati ispitivanja adsorpcije T-2 toksina na mineralu iz grupe smektita-hektoritu, na različitim pH vrednostima (3,0; 7,0 i 9,0). Ispitivanja su pokazala da adsorbovana količina T-2 toksina na hektoritu opada sa porastom sadržaja čvrste faze u suspenziji na svim ispitivanim pH vrednostima. Sa adsorpcionih izotermi se primećuje da sa povećanjem početne koncentracije T-2 toksina raste i adsorpcija T-2 toksina, na svim ispitivanim pH vrednostima. Adsorpcija T-2 toksina na hektoritu se može opisati nelinearanim (Lengmir, Langmuir) tipom izoterme na pH 3,0; 7,0 i 9,0, pri čemu faktor korelacije (r2) iznosi 0,943 na pH 3,0; 0,919 na pH 7,0 i 0,939 na pH 9,0. Maksimalna adsorbovana količina T-2 toksina na hektoritu na osnovu Lengmirove izoterme (9,178 mg g-1 na pH 3,0; 9,930 mg g-1 na pH 7,0 i 19,341 mg g-1 na pH 9,0), ukazuje da je adsorpcija T-2 toksina na hektoritu zavisna od pH. Dobijeni rezultati ukazuju na postojanje specifičnih aktivnih centara na hektoritu na kojima se T-2 toksin adorbuje.The adsorption of T-2 toxin by the natural smectite mineral-hectorite at pH 3.0, 7.0 and 9.0 was investigated. The results of T-2 toxin adsorption on hectorite showed that the T-2 adsorption capacity decreased with increasing concentration of adsorbent in the suspension for all the investigated pH values. From the adsorption isotherms, an increase in T-2 toxin adsorption with increasing initial T-2 toxin concentration was observed for all the investigated pH values. The T-2 toxin adsorption by hectorite followed a non-linear (Langmuir) type of isotherm at pH 3.0, 7.0 and 9.0, with correlation coefficients (r2) of 0.943 at pH 3.0, 0.919 at pH 7.0 and 0.939 at pH 9.0. The estimated maximum T-2 toxin adsorption by hectorite based on the Langmuir fit to the data (9.178 mg/g at pH 3.0, 9.930 mg/g at pH 7.0, and 19.341 mg/g at pH 9.0), indicated that the adsorption of T-2 toxin by hectorite is pH dependent. The obtained data suggest the existence of specific active sites in hectorite onto which the T-2 toxin is adsorbed
Influence of organic cations sorption on the point of zero charge of natural zeolite
No full textU radu su prikazani rezultati modifikovanja površine prirodnog zeolita različitim količinama (2, 5 i 10 mmol M+/100 g) oktadecildimetil benzil amonijum jona (ODMBA). Dobijeni organozeoliti su označeni kao OZ-2, OZ-5 i OZ-10. Stepen jonske izmene praćen je određivanjem sadržaja oslobođenih neorganskih katjona iz zeolita. Rezultati su potvrdili da se reakcija između ODMBA i polaznog zeolita odvija mehanizmom katjonske izmene i da je izmena kvantitativna. Dobijena vrednost za tačku nultog naelektrisanja, pHpzc, za prirodni zeolit iznosi 6,8±0,1, dok pHpzc za organozeolite OZ-2, OZ-5 i OZ-10 iznosi 7,0±0,1. Značajna razlika u pHpzc nije zapažena ni kod jednog organozeolita u odnosu na polazni mineral, što ukazuje da dobijeni organozeoliti imaju slične površinske funkcionalne grupe sa sličnim kiselo-baznim karakteristikama kao i polazni zeolit.In this paper, the results of the surface modification of natural zeolite with different amounts (2, 5 and 10 mmol M+/100g) of octadecyldimethylbenzyl ammonium ions (ODMBA) are presented. The obtained organozeolites were denoted as OZ-2, OZ-5 and OZ-10. The degree of ion exchange was followed by determination of amounts of inorganic cations released from zeolite. Results confirmed that reaction between ODMBA and starting zeolite has occurred via ion exchange mechanism. The obtained value for point of zero charge, pHpzc, of natural zeolite was 6.8±0.1, while for OZ-2, OZ-5 and OZ-10 pHpzc was 7.0±0.1. Below the pHpzc, the surfaces of materials are positive while at pH values higher than pHpzc their surfaces are negative. Compared to the pHpzc of natural zeolite, no significant differences in pHpzc was observed for all three organozeolites indicating that obtained products have similar functional groups with similar acid and basic characteristics as starting zeolite. The pHpzc was not dependent on the amount of ODMBA ions at the zeolitic surface and the value of pHpzc for all investigated sorbents is the same for all three electrolyte concentrations indicating that the pHpzc of each material is independent of the ionic strength of KNO3
Surface adsorption of stearic acid by natural calcite
No full textU radu su prikazani rezultati modifikovanja površine kalcita suvim i mokrim postupkom. Kalcit je glavni i najzastupljeniji mineral kod prirodnog krečnjaka (>95%). Ispitivanja su vršena na seriji uzoraka sa sadržajem stearinske kiseline , kao površinski aktivne materije, od 0,5, 1, 1.5, 2, 3 i 4%. Na proizvodima dobijenim suvim i mokrim postupkom modifikovanja urađena je diferencijalno termijska analiza (DTA), termo-gravimetrijska analiza (TG) i skenirajuća elektronska mikroskopija (SEM). Stepen hidrofobnosti uzoraka praćen je određivanjem indeksa obloženosti. Rezultati pokazuju da je kod mokrog postupka najveći indeks obloženosti od 99,9% dobijen je na uzorku sa sadržajem stearinske kiseline od 1,5%, a kod suvog postupka kod uzorka sa sadržajem stearinske kiseline od 3%. Rezultati termičke analize pokazuju da se osnovni egzotermni maksimum kod oba postupka javlja na približno istim temperaturama (>310°C) što ukazuje na postojanje istih aktivnih mesta na površini kalcita na kojima može biti hemisorbovana stearinska kiselina. Položaj i intenzitet ostalih egzotermnih pikova ukazuje na različito vezivanje stearinske kiseline za površinu kalcita kod mokrog i suvog postupka.In order to obtain hydrophobic material, the surface of natural limestone with the high content of calcite (>95%), was treated with 0.5, 1, 1.5, 2, 3 and 4% of stearic acid. Two methods were used for modification: the solution method and the dry coating. The obtained products were characterized using the thermal analysis (DT/TG), X-ray powder diffraction analysis (XRPD), scanning electron microscopy (SEM) and by the evaluation of floating test. Results of floating test showed that when the solution method was applied, the hydrophobicity arrived at above 99% when the amount of stearic acid was 1.5%, while with the dry coating the same hydrophobicity was achieved with 3% of stearic acid. From the position of the principal exothermic peak (> 310°C) at DTA curves, for calcites modified with dry coating and with the solution method, it can be concluded that with both modification processes, the same active sites exist at the calcite surface onto which stearic acid may be chemisorbed. However, the position and the intensity of the other exothermic peaks, indicate the differences in bonding of stearic acid at the calcite surface during the solution method and the dry coating
Adsorption of uranyl ion on acid-modified zeolitic mineral clinoptilolite
No full textU ovom radu prikazani su rezultati ispitivanja adsorpcije uranil-jona na zeolitskom mineralu klinoptilolitu modifikovanom tretmanom kiselinama. Adsorpcija je praćena pri različitim količinama čvrste faze u suspenziji kao i na različitim pH. Modifikacija je izvršena tretiranjem klinoptilolita sa kiselinama: hlorovodoničnom, oksalnom i limunskom. Polazni i modifikovani klinoptiloliti su okarakterisani termičkom analizom (DTA/TGA), određivanjem hemijskog sastava i određivanjem sadržaja izmenljivih katjona, dok su polazne kao i neadsorbovane količine uranil-jona određivane fluorimetrijskom metodom. Određeno je da je adsorpcija niska na prirodnom zeolitskom mineralu, dok kiselinski tretman značajno povećava adsorpciju uranil-jona. Kod kiselinski tretiranih klinoptilolita najviši indeksi adsorpcije uranil-jona su postignuti na uzorku dobijenom modifikacijom sa hlorovodoničnom kiselinom.In this paper, the results of adsorption of uranyl ion on acid-modified zeolitic mineral clinoptilolite are presented. Adsorption was investigated at different amounts of solid phase in suspension, as well as at different pH values. The modified clinoptilolite samples were obtained by treatment of clinoptilolite with acids: hydrochloric, oxalyc and citric. Starting and modified clinoptilolites were characterized by chemical analysis, thermal (DT/TG) analysis and by determination of cation exchange capacity, while starting and nonadsorbed amounts of uranyl ion were determined by fluorometric method. Uranyl ion adsorption experiments on natural unmodified zeolitic mineral showed that uranyl ion adsorption was low (29.2%) and that treatment of clinoptilolite with acids significantly increases the adsorption of uranyl ion (>90%). In the case of acid treated clinoptilolites, the highest adsorption of uranyl ion was achieved on clinoptilolite modified with hydrochloric acid. Kinetics of adsorption showed that adsorption of uranyl ion begins very fast and that the most of uranyl ion was adsorbed in first 30 min. Practically, there were no changes in uranyl ion adsorption within next 72 h
Modification of mineral waste by mechanical-chemical treatment
No full textU radu su prikazani rezultati tretiranja Borske flotacijske jalovine (BFJ) u cilju definisanja optimalnog tehno-ekonomskog procesa recikliranja. Borska flotacijska jalovina ima u svom sastavu makroskopski posmatrano dve komponente od kojih je jedna pirit (metalični mineral) sa oko 10% masenog učešća i 90% nemetaličnih minerala (uglavnom SiO2) koje treba razdvojiti. Preliminarna istraživanja pokazuju da mehano-hemijski (M-H) postupak aktivacije i magnetna separacija (MS) mogu doprineti razdvajanju metaličnih od nemetaličnih minerala. Pogodnim tretmanom u vibracionom mlinu uz dodatak NaOH iz minerala pirita se obrazuje molekulski kompleks jarozita sa povišenom magnetnom induktivnošću. Odvajanje pomenutog kompleksa od ostatka mineralne materije iz BFJ se vrši na visoko-gradijentnom magnetnom separatoru tako što se odabere pogodan intenzitet magnetnog polja i izvrši separacija. Osnovna ideja procesa tretiranja mineralnog otpada je da se mehano-hemijskim postupkom izvrši promena koordinacije kristalnog polja pirita u spinski kompleks jarozita, i time izvrši promena magnetičnih osobina metalične komponente BFJ. Kompleks koji nastaje iz pirita pripada takozvanoj jarozitnoj grupi minerala hemijske formule XFe3 '''[(SO4)2(OH)6], gde X može biti K, Na Mg, Ag, NH4. Nastali kompleks iz grupe jarozita je sulfat alkalija i feruma sa konstitucionalnom vodom i sa promenjenim optičkim i magnetnim osobinama a sastoji se od centralnog jona metala feruma Fe 3+ okruženog ligandima, koji se smatraju tačkastim naelektrisanjem.The paper presents the results of treatment the Bor flotation tailings (BFT) to the aim of defining the optimal techno-economic process of recycling. The Bor flotation tailings includes into its content the macroscopically seen two components out of which one is pyrite (metallic mineral) with about 10% mass participation and 90% non-metallic mineral (mainly SiO2) that have to be separated. Preliminary investigations have shown that mechanical-chemical (MCH) procedure of activation and magnetic concentration (MC) could contribute to separation of metallic from non-metallic minerals. Using the appropriate treatment in the vibrating mill with addition of NaOH from pyrite mineral, the molecular complex of jarosite is formed with high magnetic inductivity. Separation of the mentioned complex from the rest mineral matter from BFT is done on high-gradient magnetic separator by selection of suitable intensity of magnetic field and perform separation. The basic idea of treatment process of mineral waste is changing the coordination of pyrite crystal field into the spin complex of jarosite using the mechanical-chemical method and, and thus make changes in magnetic properties of metallic components of BFT. Complex arising from pyrite belongs to the so-called jarosite group of minerals of chemical formula XFe3 '''[(SO4)2(OH)6], where X could be K, Na, Mg, Ag, NH4. Formed complex from jarosite group is alkaline and ferrum sulphate with constitutional water and changed optical and magnetic properties, and consists of central metal ion ferrum Fe 3 surrounded by ligands, which are considered as a dotted charge