Surface Of Mineral Particles Research Articles

Adsorption of Enamel Matrix Proteins to a Bovine‐Derived Bone Grafting Material and Its Regulation of Cell Adhesion, Proliferation, and Differentiation

The use of various combinations of enamel matrix derivative (EMD) and grafting materials has been shown to promote periodontal wound healing/regeneration. However, the downstream cellular behavior of periodontal ligament (PDL) cells and osteoblasts has not yet been studied. Furthermore, it is unknown to what extent the bleeding during regenerative surgery may influence the adsorption of exogenous proteins to the surface of bone grafting materials and the subsequent cellular behavior. In the present study, the aim is to test EMD adsorption to the surface of natural bone mineral (NBM) particles in the presence of blood and determine the effect of EMD coating to NBM particles on downstream cellular pathways, such as adhesion, proliferation, and differentiation of primary human osteoblasts and PDL cells. NBM particles were precoated in various settings with EMD or human blood and analyzed for protein adsorption patterns via fluorescent imaging and high-resolution immunocytochemistry with an anti-EMD antibody. Cell attachment and cell proliferation were quantified using fluorescent double-stranded DNA-binding dye. Cell differentiation was analyzed using real-time polymerase chain reaction for genes encoding runt-related transcription factor 2, alkaline phosphatase (ALP), osteocalcin (OC), and collagen1α1 (COL1A1), and mineralization was assessed using red dye staining. Analysis of cell attachment and cell proliferation revealed significantly higher osteoblast and PDL cell attachment on EMD-coated surfaces when compared with control and blood-coated surfaces. EMD also stimulated release of growth factors and cytokines, including bone morphogenetic protein 2 and transforming growth factor β1. Moreover, there were significantly higher mRNA levels of osteoblast differentiation markers, including COL1A1, ALP, and OC, in osteoblasts and PDL cells cultured on EMD-coated NBM particles. The present results suggest that 1) EMD enhances osteoblast and PDL cell attachment, proliferation, and differentiation on NBM particles, and 2) blood contamination of the grafting material before mixing with EMD may inhibit EMD adsorption.

Influence of talc genesis and particle surface on the crystallization kinetics of polypropylene/talc composites

AbstractTalc is a laminar silicate, considered as an excellent nucleating agent for polypropylene (PP) crystallization. However, properties of PP/talc composites depend on the morphology, size, and surface of mineral particles. In this sense, talc from several ores, having different morphology, imparts specific characteristics on these materials. Also, taking into account that PP‐talc adhesion is not necessarily good due to the apolar character of PP, talc surface has been modified in order to increase this parameter. In this work, the effects of talc genesis, geomorphologic aspects, and particle surface characteristics on crystallization of PP/talc composites are analyzed. Isothermal crystallization of PP/talc composites was studied by using differential scanning calorimetry, based on Avrami model. The final crystalline morphology of talc‐filled PP was analyzed by means optical microscopy. The results show that the blocky talc morphology favors even more the crystallization compared to the platy one, at the same particle size. Taking into account the surface treatment studied in this work, the talc surface is made hydrophobic and the particle delamination is favored. As a consequence, so‐modified talc is very effective in increasing the crystallization temperature of PP and the nuclei number that grow during the crystallization with respect to the untreated talc. © 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012

Influences of flotation reagents on bioleaching of chalcopyrite by Acidthiobacillus ferrooxidans

This paper investigates the effects of five flotation reagents (ethyl xanthate, isopropyl xanthate, butyl xanthate, isoamyl xanthate and butylaminel) on the bioleaching capability of Acidthiobacillus ferrooxidans. It is shown that these five flotation reagents can all depress the copper extraction of At.f6 bacteria. According to the impacts from weak to strong, the inhibition effects of these five reagents on At.f6 bacteria are in the following order: butyl xanthate, isopropyl xanthate, isoamyl xanthate, ethyl xanthate, and butylamine. The analysis of SEM–EDS indicates that the surfaces of mineral particles are corroded by different degrees and that the weight proportion and atomic number proportion of Cu decrease, but the weight proportion and atomic number proportion of Fe and S increase; the degrees of change are in the same order with the inhibition effects of these five reagents on bioleaching capability of At.f6 bacteria.

Conditions of condensate rim formation on the surface of lunar regolith particles

Condensate objects observed in the lunar regolith are distinctly separated on the basis of morpho-logical and chemical characteristics into droplets condensed during the expansion of an impact-generated vapor cloud and films condensed on the relatively cold surface of mineral particles. Using the analyses of both condensate forms and experimental data on the evaporation of melt corresponding to a typical lunar highland rock of the gabbro-anorthosite composition from Apollo 16 sample 68415.40, the temperature conditions of vapor condensation during lunar impact events were estimated. The comparison of condensate compositions with the analyses of vapors from the evaporation experiment showed that, compared with the compositions of droplet-type condensates, the condensate rims were formed from a vapor with high contents of refractory CaO and Al2O3 and at very different condensation temperatures. The enrichment of vapor in CaO and Al2O3 could be attained only at high temperatures of melt evaporation (higher than ∼ 1850°C according to experimental data). The estimated condensation temperatures of droplets are significantly lower, ∼1750–1500°C. Rim-type condensates were produced by vapor quenching on the relatively cold surface of a solid mineral particle, which resulted in almost complete precipitation of all major components of the silicate vapor without fractionation in accordance with their individual volatilities.

Nanoparticle Flotation Collectors: Mechanisms Behind a New Technology

This is the first report describing a new technology where hydrophobic nanoparticles adsorb onto much larger, hydrophilic mineral particle surfaces to facilitate attachment to air bubbles in flotation. The adsorption of 46 nm cationic polystyrene nanoparticles onto 43 μm diameter glass beads, a mineral model, facilitates virtually complete removal of the beads by flotation. As little as 5% coverage of the bead surfaces with nanoparticles promotes high flotation efficiencies. The maximum force required to pull a glass bead from an air bubble interface into the aqueous phase was measured by micromechanics. The pull-off force was 1.9 μN for glass beads coated with nanoparticles, compared to 0.0086 μN for clean beads. The pull-off forces were modeled using Scheludko's classical expression. We propose that the bubble/bead contact area may not be dry (completely dewetted). Instead, for hydrophobic nanoparticles sitting on a hydrophilic surface, it is possible that only the nanoparticles penetrate the air/water interface to form a three-phase contact line. We present a new model for pull-off forces for such a wet contact patch between the bead and the air bubble. Contact angle measurements of both nanoparticle coated glass and smooth films from dissolved nanoparticles were performed to support the modeling.

Study of Adsorptive Behaviors of Aminosulfonic Acid-Based Superplasticizer on the Calcium Sulphoaluminate Mineral

Calcium sulphoaluminate (3CaO·3Al2O3·CaSO4, ) was synthesized with pure chemical reagents. The adsorbed amount of aminosulfonic acid-based superplasticizer (AS) on the surface of mineral and the mineral mixture (mixture of the , Ca(OH)2and CaSO4·2H2O) were detected by ultraviolet-visible absorption spectrometry. The adsorptive behaviors of AS on the surface of mineral particles in the hydration system were studied. The results showed that: the adsorbed amount of AS on mineral and the mineral mixture increased with higher initial concentration; the adsorption amount and the maximum adsorption amount increased with prolonged hydration time; the adsorption amount and the maximum adsorption amount of AS on the mineral mixture was more than those on the mineral in the hydration system within the same hydration time.

10.1007/s11475-008-2004-3

The literature data on the adsorption of sulfates by soils were reviewed. Factors affecting the adsorption of sulfates and the major mechanisms of sulfate adsorption were considered, including the most important of them: the ligand exchange with the formation of surface outer-and innersphere complexes and the Coulomb interaction with the surface of mineral particles. Equations describing the adsorption isotherms of sulfates are given; some methods for the mathematical simulation of sulfate ion behavior in the “soil solid phase-soil solution” system are discussed.

Adsorption of glyphosate in a forest soil: a study using Mössbauer and FT-IR spectroscopy

We studied the adsorption of glyphosate (GPS) onto soil mineral particles, using FT-IR and Mossbauer spectroscopy. From IR measurements for samples collected under native vegetation of a forest reserve, bands at 1632 and 1407 cm-1 could be attributed to the interaction between the carboxylic group of GPS and structural Al3+ and Fe3+ on the surface of mineral particles; bands at 1075 and 1000 cm-1 were observed only for cultivated soil. Mossbauer spectra for these soils were definitely fitted using a broad central doublet in addition to the magnetic component. This multiple quadrupolar component may be attributed to all non-magnetic Fe3+ contributions, including that of the GPS/Fe3+ complex.

Comparison of two methods for estimating the abundance, diversity and habitat preference of fluvial macroinvertebrates in contrasting habitats

In this research we evaluate the effects of the method used for estimating the potential surface available for benthic macroinvertebrates in macrophyte and unvegetated habitats on several metrics and habitat preference of aquatic macroinvertebrates in the upper catchment of the Henares River (Guadalajara, Central Spain). Three sampling sites were selected: a well-preserved stream (site A), a stream with no wood riparian vegetation (site B), and a straightened and deforested reach (site C). Two habitats were selected in each site: unvegetated habitat (i.e., substrata without macrophytes) and macrophyte habitat (i.e., substrata covered by macrophytes). In each habitat, six macroinvertebrate samples (including all macrophytes or mineral particles) were collected using a Hess sampler. Diversity and density of major families were referred to the surface of the Hess sampler (=Hess surface method) and to the actual surface of either mineral particles or macrophytes (=actual surface method). In general, for the actual surface method, biomass, richness, dominance, and diversity metrics were higher in the mineral habitat than in the macrophyte habitat. This trend was different for the Hess surface method. In general, densities turned out to be higher in the unvegetated habitat than in the macrophyte habitat when using the actual surface method, but the reverse occurred when using the Hess surface method. This fact is relevant for river biomonitoring, especially when reaches with different dominant substrates (macrophytes vs mineral) are compared using just one of the methods. It is concluded that the macrobenthic metrics and density values are influenced by the method used to estimate the potential available surface for aquatic macroinvertebrates.

Laboratory simulation of SO2 heterogeneous reactions on hematite surface under different SO2 concentrations

The variations of sulfate formation and optical coefficients during SO2 heterogeneous reactions on hematite surface under different SO2 concentrations were examined using in situ diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) and ion chromatograph (IC). Laboratory experiments revealed that within ambient SO2 of 0.51-18.6 ppmv, sulfate product, producing velocity, absorption and backward scattering coefficients showed an increasing trend with SO2 concentration. Under given SO2 concentration, the velocity of sulfate producing performed an evolution of initial increasing, midterm decreasing and final stabilizing. The reactive uptake and Brunauer-Emmett-Teller (BET) uptake coefficients of heterogeneous reactions rose with SO2 and exhibited high reactivities. Considering global warming, this result is important for the knowledge of heterogeneous reactions of SO2 on mineral particle surface in the atmosphere and the assessment of their impacts on radiative forcing.

On the characteristic properties of oxidation of sulfide minerals exposed to nanosecond electromagnetic pulses

High-power nanosecond electromagnetic pulses cause changes in the chemical and phase surface composition of sulfide minerals (pyrrhotite and pentlandite) and their sorption, flotation, and chemical activities. The influence of the conditions and parameters of the electric-pulse effect on the change in the amount of elemental sulfur and iron oxide on the surface of mineral particles, as well as the concentration of iron and sulfoxide ions in the aqueous mineral suspension, has been studied. The parameters of preliminary pulsed treatment of pyrrhotite and pentlandite that lead to improvement of flotation separation of minerals have been determined.

Adsorption of sulfate ions by soils (A Review)

The literature data on the adsorption of sulfates by soils were reviewed. Factors affecting the adsorption of sulfates and the major mechanisms of sulfate adsorption were considered, including the most important of them: the ligand exchange with the formation of surface outer-and innersphere complexes and the Coulomb interaction with the surface of mineral particles. Equations describing the adsorption isotherms of sulfates are given; some methods for the mathematical simulation of sulfate ion behavior in the “soil solid phase-soil solution” system are discussed.

Caseinophosphopeptides and dental protection: Concentration and pH studies

Casein-derived phosphopeptides (CPP) can protect teeth from acids produced by bacteria causing dental caries or directly from acidic foods and beverages causing dental erosion. Neither the CPP concentrations required for protection nor the effective pH range has been published and the protective mechanism is still open to debate. Using experimental protocols mimicking practical situations in which CPP and acid were present together in a hydroxyapatite model system, or in which excess CPP was removed before acid exposure and also using either Ca-saturated CPP or Ca-reduced CPP, we found that in all cases protection was 50–60% at pH 4.2. Protection increased exponentially with CPP concentration to about 10.0 mg/ml as measured in mixtures before acid addition, with little further improvement above that. Most of the protection was achieved at a more economical 4.0–6.0 mg/ml. The extent of protection was almost constant over the pH range 2.5–4.5. Our findings suggested a mechanism involving the formation of a protective coat of CPP over the mineral particle surfaces.

Identifying when microbes biosilicify: The interconnected requirements of acidic pH, colloidal SiO 2 and exposed microbial surface

This study demonstrates discernible biosilicification of natural microbial mats through batch laboratory experiments. Identification of the geochemical requirements for this process to occur includes thermodynamically favorable, but sluggish silica reaction kinetics associated with acidic conditions, and the necessity for colloidal silica rather than dissolved silicic acid species. This study provides the first results to bridge the apparent literature discrepancy between widespread, in-situ observations of microbial silicification, and the inability to demonstrate a detectable microbial impact in this process under well-constrained laboratory conditions. We compared the silica scavenging abilities of three natural microbial mats collected from Yellowstone National Park (YNP) hotsprings, relative to those of both abiotic particle (TiO 2) and solution controls at constant, near-saturated aqueous silica concentrations, while experimental pH and temperature conditions were varied, using both dissolved and colloidal SiO 2 forms. We specifically evaluated three microbial mats sampled from YNP sites all exhibiting saturation with respect to amorphous SiO 2, but possessing variable pH and temperature conditions that should reflect differential kinetics (and therefore biological opportunity) relative to silica polymerization: (1) most biologically favorable, acidic-mesophile (AM: pH 3, T = 35 °C); (2) biologically possible, but less opportune, alkaline, mesophile (ALK-M: pH 8, T = 35 °C) and (3) unlikely to be biologically favorable, alkaline-thermophile (ALK-T: pH 8, T = 80 °C). Comparison of field and laboratory results substantiates the requirements for thermodynamically favorable, but kinetically slower SiO 2 polymerization conditions. Results show that acidic moderate temperature conditions were required for an observable biosilicification impact. Moreover, they also identified for the first time, the necessity specifically for colloidal silica forms which are surface bound under acidic pH conditions, to distinguish discernible biosilicification compared to mineral particle controls. Results also highlight the important influence of mat surface characteristics in this process, specifically the extent of live, non-mineralized, exposed biological mat surface. Greater colloidal SiO 2 scavenging abilities are associated with non-mineralized microbial mat surfaces than with mineral particle surfaces or microbial mat surfaces encrusted with authigenic silica. These results are the first to demonstrate that biosilicification can be a microbially mediated, discernible geobiological process, shedding new light on the longstanding argument in the literature, and opening the door for more sensitive evaluation of this phenomenon in natural systems.

The influential role of pulp chemistry, flocculant structure type and shear rate on dewaterability of kaolinite and smectite clay dispersions under couette Taylor flow conditions

Improving the dewatering behaviour of mineral waste tailings is an important issue central to sustainable hydrometallurgical processing of minerals worldwide. Chemical additive-mediated, flocculation processes are generally employed to amply sedimentation behaviour of colloidally stable mineral dispersions. In this paper, studies carried out to investigate mineral particle surface chemistry/structure, polymeric flocculant structure type, shear rate and their links with improved dewaterability of colloidal kaolinite and smectite dispersions at pH 7.5 are presented. The results show that, following orthokinetic flocculation under laminar couette Taylor flow conditions with high molecular weight, non-ionic polyacrylamide homopolymer (PAM N), anionic polyacrylamide copolymers: carboxylate substituted (PAM A) and sulphonate substituted (PAM S), and non-conventional non-ionic polyethylene oxide (PEO), distinct clay mineral specific, polymer type and shear dependent dewatering behaviour was displayed. Sedimentation rates were markedly higher for kaolinite pulps, however and the extents of pulp consolidation were substantially similar for both kaolinite and smectite pulps under common flocculation conditions. The pulps flocculated with PAM S polymer showed greatest dewatering behaviour, followed by PEO and then PAM A and PAM N. For each flocculated pulp, an optimum shear rate which led to maximum settling rate exists and some cases led to greater consolidation for PEO based pulps. The findings which are compared with those obtained by a 2-blade impeller sheared orthokinetic flocculation exemplify how judicious choice of polymeric flocculant and shear rate may be effectively used to significantly enhance the dewaterability of colloidally stable clay mineral dispersions.

Specific features of iron behavior in soddy-podzolic and alluvial gleyed soils of the Middle Cis-Urals region

The regime of observations revealed that the Eh dynamics in soddy-podzolic and alluvial soils in the Middle Cis-Urals region depends not only on the rate of iron (hydr)oxides reduction but also on the rate of opposite reactions in the gleyed horizons. Both processes depend on the temperature. The Eh value decreases on heating in automorphic soils, when the reduction of Fe(III)-(hydr)oxide particles accelerates. On the contrary, in gley soils, the Eh decreases on cooling, probably, because of the reactions opposing the reduction of Fe(III)-(hydr)oxide particles, including Fe(II) fixation on the surface of mineral particles. Fe(III)-(hydr)oxides are, for the most part, preserved in gleyed soils of the Cis-Urals; the content of (Fe2O3)dit reaches 3.3% with iron minerals being usually represented by goethite.

Nanostructured modification of mineral particle surfaces in Ca(OH) 2–H 2O–CO 2 system

Traditionally pulverized particulates of raw minerals, such as ground calcium carbonate (GCC), wollastonite and dolomite, are usually of smooth/flat surface and pointed edges angles which have disadvantageous effects on the mechanical properties of composite polymer materials filled with the powders. On the other hand, dispersion of nanoscaled calcuim carbonate powders can not be easily achieved when filled in organic polymer, because of their huge specific surface energy and intense/strong conglomeration. Aiming at utilizing the advantages of both traditionally pulverized particles and nanosized ones and overcoming their disadvantages, a wet-coating method is developed and three kinds of raw-mineral-based composite powders have been successfully prepared by chemical precipitation in Ca(OH) 2–H 2O–CO 2 system on the pulverized particles in our group. It is shown that the composite powders of traditionally pulverized particles coated by nanosized calcium carbonate particles of 20–100 nm are of rough surface, blunt edges, larger specific surface area, compared with the uncoated powders. Some technological parameters are mainly analyzed for the coating process in the paper. Blending the coated powders to polypropylene demonstrates significant improvement in filling properties to the uncoated ones.

Positive gadolinium anomaly in surface water and ground water of the urban area Berlin, Germany

Rare-earth element (REE) distribution patterns of surface water and commonly also of ground water from industrialised and highly populated areas show anthropogenic gadolinium (Gd) anomalies. They result from the application of organic Gd compounds, such as the derivatives of the gadopentetic acid (Gd-DTPA), as a contrast medium in magnetic resonance imaging. After excretion from the human body, the Gd complex enters the surface water mostly by the effluents of sewage treatment plants. The chemical complex is very stable over at least 6 months under natural conditions. Owing to its anionic state, it is neither adsorbed onto surfaces of abundant clay mineral particles nor by particulate organic matter, both strongly contrasting with the behaviour of the free REE ions. Thus, this complex behaves like a pseudo-natural marker and provides a tool for tracing the mixing of surface and ground water with recycled water, and the infiltration of surface water into aquifers. In urban areas, where water production is commonly based on bank filtration, the anthropogenic Gd of the surface water can be followed to the water production wells. Like boron, δD and δ 18O, Gd can be used as a marker in the estimation of the recycled water fraction in ground water systems. Examples of anthropogenic Gd distribution in surface water, sewage and ground water in Berlin, Germany, are discussed. Mixing ratios of bank filtrates and ground water are estimated.

Measuring the Dielectric Parameters of Frozen Sand in Microwave Resonators

We measure the dielectric parameters of frozen sand by using a rectangular cavity resonator at frequencies 5.3–8.4 GHz. The transmission spectrum of the resonator completely filled with frozen sand shows supplementary resonances absent in the case where the resonator is filled with dry homogeneous sand. The difference of the resonance curves was observed for the cases of wetting the sand by ordinary (H2O) and heavy (D2O) water. It is supposed that the observed effects are related to percolation due to the existence and specific properties of the conducting liquid films of water on the surfaces of mineral particles. To verify this assumption, we performed measurements for the special medium consisting of a mixture of dry sand and small metal particles. This experiment showed that supplementary resonant peaks in the transmission spectrum of the resonator arise for a certain concentration of metal particles. The same effect is also observed in the case of incomplete filling of the resonator with dry sand. These anomalies can be explained by the appearance of negative dispersion of waves in the waveguide.

An aufwuchs chamber slide for high-resolution confocal laser scanning microscopy and stereo imaging of microbial communities in natural biofilms.

Aufwuchs chamber slides were constructed by attaching a silicone rubber gasket to a glass slide with epoxy cement. For biofilm growth, the slides were suspended in Cayuga Lake near Ithaca, NY, for 27 days. Biofilms in the chamber were stained with 0.05% acridine orange. After rinsing, the chamber was filled with molten 1% agarose to stabilize filaments and delicate polymer structures at the biofilm surface. Areas of biofilm approximately 0.5 mm thick on the inner face of the wall of the chamber were selected for side-on optical sectioning in a confocal laser scanning microscope (CLSM). Stacks of high-resolution optical images captured by the CLSM z-sectioning software, were used to create left-right stereo image pairs. At low magnification the stereo pairs showed 3-D details of the microbial landscape in the mature biofilms. Channels, pores, and other structural features of the biofilm matrix were observed in peripheral regions. Higher magnification images revealed the 3-D distribution of specific biofilm components such as filaments of sheathed bacteria projecting outward into the liquid milieu, and organic coatings, including bacterial cells on the surfaces of mineral particles.