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This article will focus on the alkaline leaching of gold-bearing tetrahedrite concentrate in a solution containing sodium sulfide and sodium hydroxide. This selective leaching is followed by the leaching of heavy and waste metals into the solution, which may influence the physical properties and quality of the desired product, possibly causing environmental toxicity. At the same time, the amount of gold was observed during the leaching process to increase its content in the solid phase for the possibility of recovery and subsequent extraction of the precious metal. Sodium sulfide works very effectively on sulfide minerals which include tetrahedrite, and sodium hydroxide eliminates the hydrolysis of sulfur which slows leaching. The leaching kinetics were carried out with a duration of five hours, and based on volume sampling at certain time intervals from three samples, with the characteristic NaOH concentration, the leaching efficiency was observed from the results with atomic absorption spectrometry. The solid residue containing the tetrahedrite concentrate was analyzed through X-ray photoelectron analysis spectrometry, from which the % solids content was determined, and it is also known to deduce the leached amount of metals for each sample.

Oro-pharyngeal pathophysiology, including upper esophageal sphincter (UES) and pharyngeal disorders, can be assessed by pharyngeal high-resolution manometry impedance (P-HRM-I). We aimed to establish methodology to diagnose disorders utilizing P-HRM-I, hypothesizing that the objective measures could be used to diagnose disordered deglutition evidenced by greater aspiration scores.Patients (n = 509, 18-91 years) were compared to controls (n = 120, 20-94 years). Variables measuring UES relaxation, UES opening extent, intrabolus pressure, and pharyngeal contractile strength were derived for 10 ml liquid swallows. Three associated pharyngeal pressurization patterns, which may be indicative of obstructed flow, were characterized: pan-pressurization (Type 1), distal compartmentalized pressurization (Type 2), and transient pressurization (Type 3). Deglutitive aspiration was determined from video fluoroscopy.UES relaxation pressure was best able to differentiate patients from controls (T 6.528, p 0.0001). Patients with abnormal relaxation pressure (8 mmHg) more frequently exhibited pharyngeal pressurization patterns and had adjunct evidence of reduced luminal distensibility (high intrabolus pressure and/or reduced UES opening). Utilizing this information, a diagnostic scheme was devised identifying 138 patients with UES disorder. A further 96 patients without evidence of UES disorder had abnormally weak pharyngeal pressures, confirming propulsive disorder. Amongst a sub-sample of 320 patients undergoing video fluoroscopy, those with pharyngeal pressurizations and adjunct evidence of reduced UES relaxation and/or distensibility had higher aspiration scores (Chi-square 60.169, p 0.0001).P-HRM-I can provide evidence for UES disorder based on pharyngeal pressurization patterns and abnormal findings for UES relaxation pressure, UES opening, and intrabolus pressure. Measuring pharyngeal contractility requires further optimization.

The history of exploitation of gold from the Danube River’s sandy gravels is centuries long. The extraction of valuable heavy minerals (VHM) concentrate was never intended. Our aim is to find out an effective separation process to produce monomineral concentrates of the following minerals: garnet, ilmenite, zircon, monazite, magnetite, rutile, gold. The essential condition is to use no chemistry (no flotation, leaching, activating). The experimental concentrates were prepared by sluicing on active river channel. Next, the separation results were achieved using gravity and electromagnetic methods with different magnetic intensities. The prepared rutile contained from 63.3% TiO2 to 87% TiO2. The ilmenite concentrate contained 20.5% TiO2 and 39.2% ilmenite. The garnet concentrate contained 94% garnet. The monazite concentrate contained 86.6% monazite, and the sum of REE oxides was 50.1%. The zircon concentrate containing 63.7% ZrO2 means that the prepared concentrate contained 96.1% zircon.

The combustion of fossil fuels results in creating a lot of solid wastes such as fly ash and slag. However, these environmentally unfriendly materials can be used as a raw material for alkali activation – geopolymerization. Although these wastes have been successfully used in industrial production for several decades, its use does not achieve the level of its potential. Today, to achieve a sustainable construction industry, alternative cement has been extensively investigated. Geopolymer (GP) is a kind of material that is obtained from the alkaline activator, and it can be produced from industrial wastes or by-products. The aim of this work was to describe the improvement of mechanical properties of alkali-activated binders – geopolymers made of fly ash and blast furnace slag. The effect of the addition of waste glass in three different values feed into fly ash or GGBFS, and its impact on mechanical properties (compressive and flexural strengths) of geopolymers was examined. The highest value of compressive strength was achieved with 20% waste glass addition to a fly ash sample on 90th day 58,9 MPa. The waste glass was added in the form of broken and crushed glass particles. Při spalování fosilních paliv vzniká velké množství pevných odpadů, jako je popílek a struska. Tyto ekologicky nešetrné materiály však lze využít jako surovinu pro alkalickou aktivaci - geopolymeraci. Přestože se tyto odpady již několik desetiletí úspěšně používají v průmyslové výrobě, jejich využití nedosahuje úrovně svého potenciálu. V současné době se v zájmu dosažení udržitelného stavebnictví intenzivně zkoumají alternativní cementy. Geopolymer (GP) je druh materiálu, který se získává z alkalického aktivátoru a lze jej vyrábět z průmyslových odpadů nebo vedlejších produktů. Cílem této práce bylo popsat zlepšení mechanických vlastností alkalicky aktivovaných pojiv - geopolymerů vyrobených z popílku a vysokopecní strusky. Byl zkoumán vliv přídavku odpadního skla ve třech různých hodnotách přídavku do popílku nebo GGBFS a jeho vliv na mechanické vlastnosti (pevnost v tlaku a ohybu) geopolymerů. Nejvyšší hodnoty pevnosti v tlaku bylo dosaženo při přídavku 20 % odpadního skla do vzorku popílku 90. den 58,9 MPa. Odpadní sklo bylo přidáno ve formě rozbitých a rozdrcených skleněných částic.

Magnesite ore with a low chalcopyrite – cobaltite mineralization was subjected to a series of separations designed to evaluate thepossible concentration of the two accessory minerals. Although the Cu-Co grade in the ore (> 0.01% Co, > 0.1% Cu) is significantlylower than the typical economic grades, content of the main valuable mineral for which the ore is mined and processed incombination with a listing of cobalt as a critical raw material, coupled with their higher price might compensate for the additionalbeneficiation stages. The ore was first crushed and subsequently classified to -100 μm and +100 -400 μm size fractions. The finefraction was upgraded by froth flotation processing in laboratory froth flotation cell. The coarser fraction was processed in severalseparation stages including gravity separation on shaking table, magnetic separation and corona electrostatic separation. The sameprocedure was also repeated with a higher-grade sample as a verification of the procedures. Preliminary results suggest that theaccessory minerals can be separated from the talc-magnesite ore and individual mineral concentrates with about 19% Co and 28%Cu were prepared. However, further work must be done to achieve desirable recoveries for the processing to be economically viable.

Using the separation methods, the tetrahedrite concentrate, which contains multiple elements, was obtained from the tetrahedrite ore.We focused mainly on copper, but also on iron and antimony. Ore also contains undesirable elements such as arsenic or mercury. Theaim of this paper is an efficient separation of the utility components. Gravity separation and flotation was used. The first processingstep was gravity separation on shaking table the second step was froth flotation in flotation column.

This paper investigates the effect of sodium hexametaphosphate (SHMP) depressant/dispersant in the presence of methyl isobutyl carbinol (MIBC) frother and soluble starch (SS) depressant on the flotation kinetics of talc ore. Emphasis is on a comparison between the evaluation of a custom design of experiment (DoE) using the multilinear regression analysis (MRA) and response surface methodology (RSM) approach. Although analysis of variance (ANOVA) is a good first step in the evaluation of the effect of factors on froth flotation processing, it nonetheless only reveals the effects that are the same under all conditions. In the case of SHMP, its effect on separation efficiency is positive, however, if it is used along with SS, the effect is negative. Moreover, if a higher frother dosage is used, the effect of SHMP on separation efficiency is negligible.

The contribution deal with the study on composition of tetrahedrite-bearing siderite ore from Maria Mine nearby Rožnava and of tetrahedrite concentrate prepared from this ore by froth flotation. The Rožnava ors field consists of two main vein systems, namely Mária and Strieborná (Argenteous/Silvery) ones, respectively. The both vein systems are situated in the Early Paleozoic Gelnica Group of the Gemeric Superunit, in Bystrý Potok Formation (Upper Silurian) and in the Drnava Formation (Early Devonian). The filling of vein systems is formed mainly by siderite, quartz, tetrahedrite, pyrite, arsenopyrite, chalcopyrite, ankerite, albite, pyrrhotite, marcasite, less tourmaline, sericite, chlorite, apatite, magnetite, etc. The rock surroundings is represented by quartzy metapsammite, sericitic-quartzite and sericitic-graphitic phyllites (Jakubiak, 2008, Blišt’an, 2009, Varga, 2013, Mikus, 2018). Thus, metal ore as a feed to froth flotation and obtained concentrate were subjected to grain size analysis. The grain size fractions were assayed using GA, AAS, MS-ICP and CHNS. Mineral composition of samples was studied using XRD. So, polymetal ore contains 18.99 % SiO2, 37.01 % FeO, 1.84 % MnO, 7.36 % C, 2.36 % Cu, 1.70 % Sb, 0.15 % As, 2.32 % S, 770 ppm Ag and 216 ppm Hg. Tetrahedrite concentrate containing 25.59 % Cu, 19.68 % Sb, 1.19 % As, 20.08 % S, 0.57 % Ag, 1.20 % Hg, 1 % SiO2, 16.16 % FeO, 0.48 % MnO and 2.17 % C at a mass yield of 4 % was prepared. XRD study showed that siderite occurs as a dominant mineral in metal ore. Quartz, tetrahedrite and sericite are presented as accompanying minerals. Accessories are represented by chlorite, probably clinochlore. As to flotation concentrate, tetrahedrite is dominant mineral, which accompanied by siderite. Accessories can be represented by chalcopyrite, arsenopyrite, sericite, pyrite, quartz and chlorite.

A biomimetic Zein polydopamine based nanofiber scaffold was fabricated to deliver bone morphogenic protein-2 (BMP-2) peptide conjugated titanium dioxide nanoparticles in a sustained manner for investigating its osteogenic differentiation potential. To prolong its retention time at the target site, BMP-2 peptide has been conjugated to titanium dioxide nanoparticles owing to its high surface to volume ratio. The effect of biochemical cues from BMP-2 peptide and nanotopographical stimulation of electrospun Zein polydopamine nanofiber were examined for its enhanced osteogenic expression of human fetal osteoblast cells. The sustained delivery of bioactive signals, improved cell adhesion, mineralization, and differentiation could be attributed to its highly interconnected nanofibrous matrix with unique material composition. Further, the expression of osteogenic markers revealed that the fabricated nanofibrous scaffold possess better cell-biomaterial interactions. These promising results demonstrate the potential of the composite nanofibrous scaffold as an effective biomaterial substrate for bone regeneration.

Carbon nanotubes (CNTs) have become an important nano entity for biomedical applications. Conventional methods of their imaging, often cannot be applied in biological samples due to an inadequate spatial resolution or poor contrast between the CNTs and the biological sample. Here we report a unique and effective detection method, which uses differences in conductivities of carbon nanotubes and HeLa cells. The technique involves the use of a helium ion microscope to image the sample with the surface charging artefacts created by the He+ and neutralised by electron flood gun. This enables us to obtain a few nanometre resolution images of CNTs in HeLa Cells with high contrast, which was achieved by tailoring the He+ fluence. Charging artefacts can be efficiently removed for conductive CNTs by a low amount of electrons, the fluence of which is not adequate to discharge the cell surface, resulting in high image contrast. Thus, this technique enables rapid detection of any conducting nano structures on insulating cellular background even in large fields of view and fine spatial resolution. The technique demonstrated has wider applications for researchers seeking enhanced contrast and high-resolution imaging of any conducting entity in a biological matrix - a commonly encountered issue of importance in drug delivery, tissue engineering and toxicological studies.

Slag is one of the by-products of the energy industry, which is suitable for secondary industrial processing. Although slag has been successfully used in industrial production for several decades, its use does not achieve the level of its potential. Today, to achieve a sustainable construction industry, alternative types of cement have been extensively investigated. Geopolymer is a kind of material which is obtained from the alkaline activator and it can be produced from the industrial wastes or by-products. In this study, SiO2/Na2O ratio and the amount of Na2O in activation solution parameters of alkali-activated materials were tested how they affect the strengths of hardened geopolymers from ground granulated blast furnace slag (GGBFS). Compressive and flexural strength tests were conducted, and the results were analyzed by analysis of variance (ANOVA). Strengths were tested after 7, 28, and 90 days.

International audience; Growth and survival of biological cells (eukaryotes and prokaryotes) on artificial environments often depend on their interactions with the specific surface. Various organic materials can be coated on substrates to assist cells' adhesion and other subsequent cellular processes. However, these coatings are expensive, degrade over short time period, and may even interfere with the cells' signaling processes. Therefore, the use of inorganic surfaces in order to control cellular interactions is of scientific importance from fundamental and application perspectives. Among inorganic materials, oxide thin films have received considerable attention. Thin films of oxides have the advantage of tailoring the surfaces for cellular interactions while using a negligible amount of the oxide material. Here, we review the lesser known application of inorganic oxide coatings as biocompatible and implantable platforms for different purposes, such as biofilm inhibition, cell culture and implant enhancements.

In this manuscript, we demonstrate a method based on atomic force microscopy which enables local probing of surface wettability. The maximum pull-off force, obtained from force spectroscopy shows a remarkable correlation with the macroscopically observed water contact angle, measured over a wide variety of surfaces starting from hydrophilic, all the way through to hydrophobic ones. This relationship, consequently, facilitates the establishment of a universal behaviour. The adhesion forces scale with the polar component of surface energy. However, no such relation could be established with the dispersive component. Hence, we postulate that the force(s) which enable us to correlate the force spectroscopy data measured on the nanoscale to the macroscopic contact angle are primarily arising from electrostatic-dipole-dipole interactions at the solid-liquid interface. London forces play less of a role. This effect in is line with density functional theory (DFT) calculations suggesting a higher degree of hydroxylation of hydrophilic surfaces. This result shows that molecular simulations and measurements on an atomic scale can be extrapolated to macroscopic surface wetting problems.

This work describes improvement of mechanical properties of alkali activated binders – geopolymers made of fly ash from coal combustion in fusion boiler. The effect of addition of amorphous phase on physico-mechanical properties of geopolymers was examined. The studied properties were: flexural strength, compressive strength and water absorption. Effect of preparation process on the final properties of samples was also discussed. Amorphous phase was added in form of slag from the same coal combustion boiler. Samples were tested after 7, 28 and 90 days. With increasing amount of slag, the ascending trend of compressive strength was observed at the early stages of maturing. Compressive strength values measured after 90 days of maturing were found almost the same for all slag concentrations, and outperformed the compressive strength value of reference sample. On the contrary, the flexural strength was not positively affected by addition of the slag. Regarding the water absorption, the higher the slag addition, the lower water absorption was measured.

With the rise in nosocomial infections worldwide, research on materials with an intrinsic ability to inhibit biofilm formation has been generating a great deal of interest. In the present work, we describe how thin film material libraries generated by pulsed laser deposition can be used for simultaneously screening several novel metal oxide mixtures that inhibit biofilm formation in a common human pathogen, Salmonella enterica serovar Typhimurium. We discovered that in a material library constructed using two metal oxides, the net effect on biofilm formation can be modeled as an addition of the activities of the individual oxides weighted to their relative composition at that particular point on the library. In contrast, for similar material libraries constructed using three metal oxides, there was a nonlinear relation between the amount of dominant metal oxide and the formation of Salmonella biofilms. This nonlinearity resulted in several useful metal oxide combinations that were not expected from the weighted average predictions. Our novel application will lead to the discovery of additional alternatives for creating antimicrobial surfaces.

At the nano-bio interface, human plasma differentially interacts with engineered nanomaterials through the creation of protein coronas, which in turn become primary determinants of both the pharmacokinetics and pharmacodynamics of circulating nanoparticles. Here, for the first time, the specific binding kinetics of the four major corona forming proteins (human serum albumin, fibrinogen, ApoA1, and polyclonal IgG) are determined for gold nanoparticles (AuNPs). Using a multiplexed surface plasmonic assay, highly reproducible measurements of on rate (k(on)), off rate (k(off)), and disassociation constant (K(D)), in addition to relative amounts of protein binding, are obtained. Dramatic differences in k(on) for individual components are shown as primary determinants of protein affinities, with k(on) ranging over nearly two orders of magnitude for the proteins studied, while k(off) remains within a factor of two for the set. The effect of polyethylene glycol (PEG) modification on plasma component binding is also studied and the effect of PEG length on human serum interaction is characterized through systematic screening of PEG molecular weight (2-30k). The effect of nanoparticle modification on particle targeting is also characterized through study of a hybrid AuNP system.

A biomimetic Zein polydopamine based nanofiber scaffold was fabricated to deliver bone morphogenic protein-2 (BMP-2) peptide conjugated titanium dioxide nanoparticles in a sustained manner for investigating its osteogenic differentiation potential. To prolong its retention time at the target site, BMP-2 peptide has been conjugated to titanium dioxide nanoparticles owing to its high surface to volume ratio. The effect of biochemical cues from BMP-2 peptide and nanotopographical stimulation of electrospun Zein polydopamine nanofiber were examined for its enhanced osteogenic expression of human fetal osteoblast cells. The sustained delivery of bioactive signals, improved cell adhesion, mineralization, and differentiation could be attributed to its highly interconnected nanofibrous matrix with unique material composition. Further, the expression of osteogenic markers revealed that the fabricated nanofibrous scaffold possess better cell-biomaterial interactions. These promising results demonstrate the potential of the composite nanofibrous scaffold as an effective biomaterial substrate for bone regeneration.

The article aim is to analyze the influence of mechanical activation of a fly ash, with different proportion of mechanically activated and not mechanically activated material on alkali activation. The paper describes fly ash based geopolymers and their mechanical properties. Fly ashes were mixed in four different ratios with mechanically activated fly ash. Activation solution was constant in all specimens. Compressive and flexural strengths of the hardened product were tested after 7 and 28 days of the storage in laboratory conditions and samples were cured after activation in hot air chamber for 6 hours in 80°C temperature. The results show how mechanical activation of materials affects their strengths with highest amount achieved was 44 MPa.

A common strategy by which bacterial pathogens reside in humans is by shifting from a virulent lifestyle, (systemic infection), to a dormant carrier state. Two major serovars of Salmonella enterica, Typhi and Typhimurium, have evolved a two-component regulatory system to exist inside Salmonella-containing vacuoles in the macrophage, as well as to persist as asymptomatic biofilms in the gallbladder. Here we present evidence that SsrB, a transcriptional regulator encoded on the SPI-2 pathogenicity-island, determines the switch between these two lifestyles by controlling ancestral and horizontally-acquired genes. In the acidic macrophage vacuole, the kinase SsrA phosphorylates SsrB, and SsrB~P relieves silencing of virulence genes and activates their transcription. In the absence of SsrA, unphosphorylated SsrB directs transcription of factors required for biofilm formation specifically by activating csgD (agfD), the master biofilm regulator by disrupting the silenced, H-NS-bound promoter. Anti-silencing mechanisms thus control the switch between opposing lifestyles. DOI: http://dx.doi.org/10.7554/eLife.10747.001, eLife digest Salmonella bacteria can infect a range of hosts, including humans and poultry, and cause sickness and diseases such as typhoid fever. Disease-causing Salmonella evolved from harmless bacteria in part by acquiring new genes from other organisms through a process called horizontal gene transfer. However, some strains of disease-causing Salmonella can also survive inside hosts as communities called biofilms without causing any illness to their hosts, who act as carriers of the disease and are able to pass their infection on to others. So how do Salmonella bacteria ‘decide’ between these two lifestyles? Previous studies have uncovered a regulatory system that controls the decision in Salmonella, which is made up of two proteins called SsrA and SsrB. To trigger the disease-causing lifestyle, SsrA is activated and adds a phosphate group onto SsrB. This in turn causes SsrB to bind to and switch on disease-associated genes in the bacterium. However, it was less clear how the biofilm lifestyle was triggered. Desai et al. now reveal that the phosphate-free form of SsrB – which was considered to be the inactive form of this protein – plays an important role in the formation of biofilms. Experiments involving an approach called atomic force microscopy showed that the unmodified SsrB acts to stop a major gene that controls biofilm formation from being switched off by a so-called repressor protein. Salmonella acquired SsrB through horizontal gene transfer, and these findings show how this protein now acts as a molecular switch between disease-causing and biofilm-based lifestyles. SsrB protein is also involved in the decision to switch between these states, but how it does so remains a question for future work. DOI: http://dx.doi.org/10.7554/eLife.10747.002

Jian Li,1 Sia Lee Yoong,2 Wei Jiang Goh,2 Bertrand Czarny,1 Zhi Yang,1 Kingshuk Poddar,2,3 Michal M Dykas,2,3 Abhijeet Patra,2,3 T Venkatesan,2,3 Tomasz Panczyk,4 Chengkuo Lee,5 Giorgia Pastorin1–3 1Department of Pharmacy, National University of Singapore, 2NUS Graduate School for Integrative Sciences and Engineering, Centre for Life Sciences (CeLS), 3NUSNNI-NanoCore, National University of Singapore, Singapore; 4Institute of Catalysis and Surface Chemistry, Polish Academy of Sciences, Cracow, Poland; 5Department of Electrical and Computer Engineering, National University of Singapore, Singapore Abstract: Carbon nanotubes’ (CNTs) hollow interior space has been explored for biomedical applications, such as drug repository against undesirable inactivation. To further devise CNTs as smart material for controlled release of cargo molecules, we propose the concept of “gold-carbon nanobottles”. After encapsulating cis-diammineplatinum(II) dichloride (cisplatin, CDDP) in CNTs, we covalently attached gold nanoparticles (AuNPs) at the open-tips of CNTs via different cleavable linkages, namely hydrazine, ester, and disulfide-containing linkages. Compared with our previous study in which more than 80% of CDDP leaked from CNTs in 2 hours, AuNPs were found to significantly decrease such spontaneous release to

A simple procedure was developed for the fabrication of electrochemical glucose biosensors using glucose oxidase (GOx), with graphene or multi-walled carbon nanotubes (MWCNTs). Graphene and MWCNTs were dispersed in 0.25% 3-aminopropyltriethoxysilane (APTES) and drop cast on 1% KOH-pre-treated glassy carbon electrodes (GCEs). The EDC (1-ethyl-(3-dimethylaminopropyl) carbodiimide)-activated GOx was then bound covalently on the graphene- or MWCNT-modified GCE. Both the graphene- and MWCNT-based biosensors detected the entire pathophysiological range of blood glucose in humans, 1.4-27.9 mM. However, the direct electron transfer (DET) between GOx and the modified GCE's surface was only observed for the MWCNT-based biosensor. The MWCNT-based glucose biosensor also provided over a four-fold higher current signal than its graphene counterpart. Several interfering substances, including drug metabolites, provoked negligible interference at pathological levels for both the MWCNT- and graphene-based biosensors. However, the former was more prone to interfering substances and drug metabolites at extremely pathological concentrations than its graphene counterpart. © 2013 by the authors.

Dochody inwestorow bezpośrednich (glownie dywidendy) od lat stanowią istotną cześc ujemnego salda obrotow biezących bilansu platniczego. Autorzy podjeli sie zadania weryfikacji wymienianych w literaturze przedmiotu czynnikow, wplywających na decyzje o wyplacie dywidend w przedsiebiorstwach z udzialem zagranicznego inwestora bezpośredniego, pod wzgledem ich istotności i kierunku oddzialywania. W badaniu obejmującym lata 2012–2014, oszacowano tobitowe modele dla danych panelowych, uwzgledniające m.in. finansowanie dlugiem. Analize oparto na zbilansowanym panelu obejmującym 3437 jednostek.