Search

Carbonation of industrial solid wastes containing calcium silicate can reduce CO 2 emissions as well as produce useful building materials. However, until a fully understanding of the hardening and solidification mechanism of solid wastes is obtained, their utilization in engineering applications may remain limited. In respect of this, the present work examined the effect of sodium hydroxide (NaOH) on the carbonation degree and carbonation products structure of β-dicalcium silicate (β-C 2 S) by using the X-ray diffraction (XRD), Fourier transform infrared spectrometer (FT-IR) and scanning electron microscopy (SEM-EDS), respectively. Moreover, the soluble sodium ions content and pH values of samples suspension were also monitored by using a five channel flame photometer and a digital pH meter, respectively. The results indicated that sodium hydroxide was adverse to the carbonation of β-C 2 S. In the presence of NaOH, stabilized vaterite phase was formed and the polymerization degree of silicon dioxide gels was also decrease. In turn, soluble sodium ions could be solidified in vaterite crystal structure and the pH values after carbonation was also decreased, providing a new insight into potential means to utilize alkaline solid wastes by carbonation, safely. [ABSTRACT FROM AUTHOR]

Carbon-coated Si–SiO x –Al 2 O 3 composite materials were prepared via a two-step process involving a high-energy mechanical milling and a pyrolysis reaction, and their electrochemical properties were subsequently examined for use as anode materials for Li-ion batteries. To synthesize the nanocrystalline Si embedded SiO x composite, amorphous SiO 2 and metallic Al were chosen as the best pair of starting materials. First, a simple high-energy mechanical milling process was performed to partially reduce amorphous SiO 2 using Al metal. Al was spontaneously oxidized to Al 2 O 3 ; this resulted in a nanocrystalline Si dispersed amorphous SiO x –Al 2 O 3 phase. Second, the composite was heat-treated in the presence of naphthalene as a carbon source. Through the pyrolysis reaction of naphthalene, an amorphous carbon coating layer was obtained; this layer stabilized the crystal structure of SiO x –Al 2 O 3 . The materials properties of the composites were investigated using various analytical tools. Electrochemical tests showed that the carbon-coated composite electrode exhibited good cycling stability up to 300 cycles. This performance can be attributed to the effect of the carbon coating, which both facilitated fast electronic and Li + ionic transport and played a buffering role in the large volume change of the Si-based anode materials. [ABSTRACT FROM AUTHOR]

Silica related nanovehicles are being widely studied for bioapplication, while the use in vivo has been restricted due to the biodegradation reluctance. Herein, a facile Mn-doping method was used to endow the upconversion nanoparticles (UCNPs) with a biodegradable shell, simply by transforming mesoporous silica coated UCNPs (UCNPs@mSiO2) to Mn-doped upconversion nanocapsules (Mn-UCNCs). The yolk-structured Mn-UCNCs have huge internal space, which is greatly beneficial for DOX (a chemotherapeutic agent) storage. Furthermore, the Mn-doped nanoshell is responsive to mild reductive and acidic tumor condition, which enables the biodegradation of the silica shell in tumor sites and further accelerates the breakup of Si-O-Si bonds within the silica framework. This tumor-sensitive degradation of the shell not only facilitates DOX release in the tumor location but also allows faster nanoparticle diffusion and deeper tumor penetration, thus realizing efficient particle distribution and improved chemotherapy. Moreover, the biodegradability-enhanced DOX release brings a rapid recovery to the total emission intensity and a drastic decline to the red/green (R/G) ratio, which can be used to sense the drug release extent. The MRI effect caused by Mn release coupled with the inherent MRI/CT/UCL imaging derived from the UCNPs (NaGdF4:Yb,Er@NaGdF4:Yb) under NIR irradiation endow the nanocarrier with superior multiple imaging functions. The high biocompatibility of PEGylated Mn-UCNCs was validated, and the excellent anticancer effectiveness of the DOX loaded nanosystem was also achieved. [ABSTRACT FROM AUTHOR]

Petrological-geochemical study showed that the alkaline-ultramafics of the Jetty Oasis (rift zone of the Lambert glacier, East Antarctica) are similar in the age (117-110 Ma) and geochemistry to the ultrapotassic alkali basalts of eastern India (Jharia and Raniganj intrusions). Alkaline magmatism in India and Antarctica is related to the activity of the Kerguelen plume, which significantly affected the evolution of the entire eastern Indian Ocean, in particular, determined geodynamic peculiarities of the ocean opening (existence of non-spreading blocks, fragments of the Gondwana lithosphere in oceanic areas) and geochemical characteristics of erupted tholeiitic magmas. Enriched magma sources related to the Kerguelen plume were formed by melting of ancient Gondwana-derived continental fragments, which experienced multiple transformations during its evolution up to the formation of metasomatized mantle under the impact of the Kerguelen plume on the Antarctic and India margins. [ABSTRACT FROM AUTHOR]

We investigate binding of the tripeptides Lys-Trp-Lys (KWK) and Glu-Trp-Glu (EWE) to the amorphous silica surface using atomistic simulations. These peptides were chosen because they were previously utilized in experiments measuring binding affinity and steady-state fluorescence anisotropy from the indole chromophore of the tryptophan residue. Our simulations were performed using silica with surface change density of −0.8 elementary charges per square nanometer, which is expected at neutral pH. Even though positive charged KWK binds more strongly to the negatively charged silica surface, EWE also forms bound complexes with the surface that are stable for at least 15 ns of simulation, in agreement with the experiments which revealed evidence for binding of both KWK and EWE to silica. Binding mechanisms include a wide variety of electrostatic interactions, as well as hydrophobic interactions between the indole group and hydrophobic areas of the heterogeneous silica surface. The long-time limit of the fluorescence anisotropy of tryptophan is calculated from the simulations in order to help interpret the recent experiments. We identify several factors which control the magnitude of the fluorescence anisotropy for each binding configuration. [ABSTRACT FROM AUTHOR]

The hydrothermal stability of microporous silica hybrid sol-gel derived membranes is often only tested for either the mesoporous intermediate membrane layer or the microporous separation layer. In this work an investigation is done on the interaction between the intermediate γ-alumina layer and the hybrid (BTESE-derived) silica separation layer during hydrothermal treatment. Although bare γ-alumina is degraded during a hydrothermal treatment, a coating of hydrophobic BTESE on γ-alumina retains its gas separation performance, albeit with a lower mechanical adhesion between the hybrid silica separation layer and the γ-alumina intermediate layer. Applying a monoaluminumphosphate (MAP) coating between the α-alumina support and the γ-alumina layer stabilizes the γ-alumina membrane. A BTESE coating on a MAP modified γ-alumina membrane did not show any signs of delamination after hydrothermal testing. Moreover, a significant increase in the H 2 / N 2 (perm)selectivity, factor 3, was observed for these membranes. [ABSTRACT FROM AUTHOR]

A kind of classic nanocomposite, in which nano-RDX (~60 nm) was embedded inside as the core and nano-SiO (~6 nm) compactly coated on its surface, was successfully prepared by an improved supercritical SEDS method. Therein, a special design of the nozzle made the fabrication realized. Analyses, such as SEM, TEM, XRD, IR, and XPS, were employed to investigate the micron morphology and structure of the nanocomposite. Thermal analysis was also conducted, and the DSC traces collected at different heating rate were obtained. Using these DSC data, we calculated the kinetic and thermodynamic parameters for thermal decomposition of raw RDX, RDX/SiO nanocomposite, and a simple mixture ([RDX + SiO]), by which the characteristic of the decomposition was depicted clearly. It was confirmed that for different samples, the parameters such as E , Δ H , and T changed remarkably. Meanwhile, the decomposition products were also probed with DSC-IR analysis. The results indicated that the main products for both raw RDX and RDX/SiO were CO, NO, and NO. However, the detected signal intensity of NO for RDX/SiO was much stronger than that for raw RDX. In addition, testing of mechanical sensitivity disclosed that RDX/SiO was far more insensitive than raw RDX, and then the mechanism about this was discussed. [ABSTRACT FROM AUTHOR]

Biological monitoring (BM) is a useful way of determining overall exposures to chemical substances; however, in the case of respirable crystalline silica (RCS), this has not been analytically feasible in conventional biological matrices. The aim of this study was to investigate the utility of exhaled breath condensate (EBC) as a potential biological matrix in which to determine exposure to RCS. A small pilot study was undertaken collecting EBC from six quarry workers and six occupationally unexposed persons; the samples were analysed using both single particle inductively coupled plasma mass spectrometry (spICP-MS) and transmission electron microscopy (TEM). The results showed that EBC obtained from the occupationally unexposed persons exhibited low background levels of dissolved silica whilst silica particles of various sizes were present in samples from quarry workers. This is the first study to report EBC as a potential biological matrix that allows differentiation of RCS concentrations between samples from workers and occupationally unexposed controls. The results shown here confirm the presence of RCS in EBC by both spICP-MS and TEM. However, there are difficult analytical challenges still to be overcome before this can be used as a BM method to determine workplace exposure, these are currently being investigated. [ABSTRACT FROM AUTHOR]

The encapsulation mechanism of DNA in sol-gel derived silica has been explored in order to elucidate the effect of DNA conformation on encapsulation and to identify the nature of chemical/physical interaction of DNA with silica during and after sol-gel transition. In this respect, double stranded DNA and dAMP (2′-deoxyadenosine 5′-monophosphate) were encapsulated in silica using an alkoxide-based sol-gel route. Biomolecule-encapsulating gels have been characterized using UV-Vis, 29Si NMR, FTIR spectroscopy and gas adsorption (BET) to investigate chemical interactions of biomolecules with the porous silica network and to examine the extent of sol-gel reactions upon encapsulation. Ethidium bromide intercalation and leach out tests showed that helix conformation of DNA was preserved after encapsulation. For both biomolecules, high water-to-alkoxide ratio promoted water-producing condensation and prevented alcoholic denaturation. NMR and FTIR analyses confirmed high hydraulic reactivity (water adsorption) for more silanol groups-containing DNA and dAMP encapsulated gels than plain silica gel. No chemical binding/interaction occurred between biomolecules and silica network. DNA and dAMP encapsulated silica gelled faster than plain silica due to basic nature of DNA or dAMP containing buffer solutions. DNA was not released from silica gels to aqueous environment up to 9 days. The chemical association between DNA/dAMP and silica host was through phosphate groups and molecular water attached to silanols, acting as a barrier around biomolecules. The helix morphology was found not to be essential for such interaction. BET analyses showed that interconnected, inkbottle-shaped mesoporous silica network was condensed around DNA and dAMP molecules. [ABSTRACT FROM AUTHOR]

Lithogeochemical characterization of the Road River Group and Canol and Imperial formations as exposed at an outcrop on Trail River, eastern Richardson Mountains, documents the evolution of a Laurentian-margin basin during the latest Eifelian through middle Frasnian stages. δ13Corg stable isotope data correlated to conodont-constrained global isotopic curves indicates deposition of the section from ≥387.7 to ≤376.7 Ma. The uppermost Road River Group is latest Eifelian and older in age (≥387.7 Ma) and is primarily calcareous and dolomitic shale and mudstone, representing a slope environment below a carbonate platform that experienced cyclical turbidity current deposition. A 2.3 m, metalliferous and concretionary unit lies transitionally between the Road River Group and Canol Formation and is herein designated as an informal, conformable, lithologic unit called the Road River - Canol transition zone (RCTZ), which records 4.5 Ma of condensed sediment deposition during the Givetian stage (387.7-383.2 Ma). The Canol Formation is confined to the latest Givetian to middle Frasnian stages (383.2-376.7 Ma) and consists of rhythmically bedded, biogenically sourced, siliceous shale and chert that was deposited in an anoxic (and likely euxinic) to oxic basin that evolved from moderately to strongly hydrographically restricted over time. The lowermost Imperial Formation is a siliciclastic mudstone, which documents turbidity current deposition in oxic bottom water conditions in the late Frasnian (≤376.7 Ma). Interpretation of lithofacies, whole-rock geochemistry, mineralogy, and total organic content enable the section to be grouped into eight lithochemozones that record a first-order late-stage sea-level transgression (Road River Group and RCTZ), highstand (lower Canol Formation), and early-stage regression (upper Canol Formation) followed by continued falling stage sea-level conditions with strong detrital influence from a continental collision in the high Arctic (Imperial Formation). [ABSTRACT FROM AUTHOR]

To restrain the migration and extractability of the antioxidants and improve the dispersion of nanosilica in natural rubber (NR), antioxidant 2- tert-butyl-6-(3- tert-butyl-2-hydroxy-5-methylbenzyl)-4-methyphenyl acrylate (GM) functionalized nanosilica was prepared using antioxidant coupling agent (KH590-GM) as functional modifier, which was first synthesized through thiol-ene reaction between the mercapto group of γ-mercaptopropyl trimethoxysilane (KH590) and the CC double bonds of antioxidant GM. Fourier transform infrared spectroscopy and 1H nuclear magnetic resonance confirmed the structure of KH590-GM and GM functionalized nanosilica. Thermogravimetry analysis indicated that the grafting rate of GM functionalized nanosilica reached 13.4%, and the antioxidant had good thermal stability. Scanning electron microscope and mechanical properties measurement showed GM functionalized nanosilica was dispersed uniformly in NR vulcanizates, and helpful for the increase of the tensile strength and tensile stress of NR vulcanizates. Based on the study of the antioxidative behavior and extraction resistance of the NR vulcanizates, it was found that in contrast to NR vulcanizates with GM, the ageing coefficient and oxidation induction time of that with GM functionalized nanosilica increased to 0.66 and 39 min from 0.58 and 30 min, respectively. Furthermore, the NR vulcanizates with GM functionalized nanosilica also exhibited excellent extraction resistance. POLYM. COMPOS., 38:1241-1247, 2017. © 2015 Society of Plastics Engineers [ABSTRACT FROM AUTHOR]

Ultra-thin SiO x layers were inserted between amorphous and crystalline silicon to improve the passivation effect in heterojunction (HJ) solar cells. To investigate the effect of oxide films on passivation, non-destructive and surface sensitive techniques were applied to characterize the surface. X-ray photoelectron spectroscopy (XPS) results revealed the coexistence of intermediate-oxidation states in SiO x layers, where the presence of Si + and Si 2+ correlated to a degradation of the passivation. Meanwhile, the distribution of intermediate-oxidation states was correlated to the surface roughness. In addition, the enhanced passivation layers fabricated in chemical solutions were demonstrated to feature the lowest film density resulting from the presence of a cage-like bonding configuration. [ABSTRACT FROM AUTHOR]

Post-synthetic modification of the zirconium-based metal-organic framework (MOF) NU-1000 by atomic layer deposition (ALD), using tetramethoxysilane (Si(OMe)4) as a precursor, led to the incorporation and stabilization of silicon oxide clusters composed of only a few silicon atoms in the framework's pores. The resulting SiO x functionalized material (Si-NU-1000) was found to be catalytically active despite the inactivity of related bulk silicon dioxide (SiO2), thus demonstrating the positive effects of having nanosized clusters of SiO x. Moreover, Si-NU-1000 showed activity greater than that found for aluminum oxide based catalysts-oxides known for their high acidity-such as an aluminum oxide functionalized MOF (Al-NU-1000) and bulk γ-Al2O3. X-ray photoelectron spectroscopy and infrared spectroscopy measurements unmasked the electron donating nature of Si-NU-1000, explaining the unusual electronic properties of the nanosized SiO x clusters and supporting their high catalytic activity. [ABSTRACT FROM AUTHOR]

The Fischer–Tropsch (FT) synthesis is an important method for producing valuable key raw materials such as heavy and light hydrocarbons in various industries. The effects of process conditions (temperature of 503–543 K, pressure of 10–25 bar, and gas hourly space velocity (GHSV) of 1,800–3,600 Nml gcat−1h−1) on the FT product distribution using Co–SiO2/SiC catalyst in a fixed bed reactor were studied by the design of experimental procedure and the Taguchi method. The optimization of the reaction conditions for the production selectivity of C2–C4and heavy hydrocarbon (C5+) that has not been completely indicated elsewhere was investigated. The effect of operating conditions on the average carbon number distribution, dispersion, and skewness was also studied. Data analysis indicated the highest selectivity for the light hydrocarbons at a pressure of 20 atm, GHSV of 2,400 Nml gcat−1h−1, and temperature of 543 K resulting in a highest selectivity for heavier hydrocarbons (C5+) and the minimum amount of methane in the reaction products that is optimal at the pressure of 10 atm, GHSV of 1,800 Nml gcat−1h−1, and a temperature of 503 K. Furthermore, based on the surface plot, temperature has more significant effects than the other parameters. In addition, the obtained results indicated that the maximum average number of carbon was obtained in a pressure of 10 atm and a temperature of 503 K. [ABSTRACT FROM PUBLISHER]

Development of mesoporous structures of composite silica particles with various organic functional groups was investigated by using a two-step process, consisting of one-pot sol-gel process in the presence and absence of ammonium hydroxide and a selective dissolution process with an ethanol-water mixture. Five different organosilanes, including methyltrimethoxysilane (MTMS), 3-mercaptopropyltrimethoxysilane (MPTMS), phenyltrimethoxysilane (PTMS), vinyltrimethoxysilane (VTMS), and 3-aminopropyltrimethoxysilane (APTMS) were employed. The mesoporous (organically modified silica) ORMOSIL particles were obtained even in the absence of ammonium hydroxide when the reaction mixture contained APTMS. The morphology of the particles, however, were different from those prepared with ammonia catalyst and the same organosilane mixtures, probably because the overall hydrolysis/condensation rates became slower. Co-existence of APTMS and VTMS was essential to prepare mesoporous particles from ternary organosilane mixtures. The work presented here demonstrates that organosilica particles with desired functionality and desired mesoporous structures can be obtained by selecting proper types of organosilane monomers and performing a facile and mild process either with or without ammonium hydroxide. [ABSTRACT FROM AUTHOR]

The application domains of classic enzyme-linked ligand binding assay (ELBA) is relatively narrow due to the high cost and hardly available binding receptor. In here, we described for the first time the possibility of developing a new ELBA based on silica nanoparticles (nano-SiO 2 ) to assess the ibuprofen in human urine. Nano-SiO 2 with a large surface area was introduced as stationary phase to improve the analytical performance. In the experiment, a competitively binding procedure with human serum albumin (HSA) was performed between the ibuprofen presented in sample and horseradish peroxidase labeled ibuprofen (HRP-ibuprofen) subsequently added. After centrifugal separation, the HRP/ibuprofen/nano-SiO 2 composite catalyzed the substrate solution (TMB/H 2 O 2 ) with a color change from colorless to yellow for quantitative measurement via an ultraviolet spectrophotometer. As a validation of the new principle, the developed nano-ELBA method was applied in the determination of ibuprofen excreted in human urine with excellent performance. This detection range only depends on the solubility of ligand and sensitivity of UV spectrophotometer. Our results indicate that this new method demonstrated to be able to rapidly and adequately determine the concentration of components in biological samples and advocate its effectiveness for various applications. [ABSTRACT FROM AUTHOR]

A fast method was optimized and validated for simultaneous trace determination of four polycyclic aromatic hydrocarbons: benzo[ a ]anthracene, benzo[ b ]fluoranthene, benzo[ k ]fluoranthene and benzo[ a ]pyrene in bovine tissues. The determination was performed by matrix solid-phase dispersion (MSPD) coupled on-line to solid phase extraction (SPE) and high performance liquid chromatography (HPLC) with fluorescence detection (FLD). The sample was dispersed on C 18 silica sorbent and then the on-line MSPD-SPE-HPLC/FLD method was applied. Several parameters were optimized: cleaning and elution sequences applied to the MSPD cartridge, the flow rate and dilution of extract used for SPE loading. The on-line method was validated over a concentration range of 0.1–0.6 ng g −1 obtaining good linearity (r ⩾ 0.998) and precision (RSD) ⩽ 10%. Recovery ranged from 96 to 99% and the limits of detection were 0.012 ng g −1 . This methodology was applied to liver samples from unhealthy animals. The results demonstrate that MSDP-SPE-HPLC/FLD method provides reliable, sensitive, accurate and fast data to the food control. [ABSTRACT FROM AUTHOR]

Differentiating the chemical properties of the external and pore surfaces of sol-gel derived mesoporous materials by selective functionalization is important to advancing their application as platforms for biological catalysis, sensing and drug delivery. Prior selective functionalization approaches to concentrating functional groups at the external surface of particles have been limited to small pores (≤5.5 nm diameter) incapable of loading large biological molecules. This work investigates the selective exterior surface functionalization by amines of larger-pored (>7 nm diameter) mesoporous silica particles, which are synthesized by dual surfactant templating and hydrothermal aging. Previously developed selective functionalization techniques rely on choice of functionalization precursor, functionalization reaction time, or pore blocking (by leaving pore templates in as-synthesized materials). The effectiveness of these strategies are compared for larger-pored materials using the precursors (3-aminopropyl)tris(methoxyethoxyethoxy)silane (APTMEES) and (3-aminopropyl)triethoxysilane (APTES). The extent of amine functionalization is determined as a function of precursor reaction time (10 or 20 min) in both as-synthesized and template-extracted materials by confocal laser scanning microscopy of the ∼10 μm diameter particles tagged with fluorescein isothiocyanate. Reaction time, regardless of pore template presence, is demonstrated to be the controlling variable for achieving selective exterior functionalization in these larger pored mesoporous materials. Under the conditions used, 10 min of functionalization with APTMEES localizes amine groups at the exterior of the particles, while 20 min functionalizes both the exterior and the interior pore surfaces. Protein accessibility within pores, before and after selective and full functionalization, is visually confirmed by confocal fluorescence imaging of Rhodamine B tagged lysozyme loaded particles. [ABSTRACT FROM AUTHOR]

Tensile and compressive creep tests of fly ash concretes in the hardening phase have been performed in the Temperature-Stress Testing Machine (TSTM) at NTNU. All tests were performed under nominally identical conditions, e.g. dimensions, curing conditions, measurement set-up and load-regime. Two concretes with 17% and 33% fly ash (as % by weight of cement and fly ash content) were investigated. Contradictorily to most of the compressive versus tensile creep comparisons found in the literature, both the investigated concretes showed similar creep behaviour in compression and tension throughout the hardening phase. It was also seen that for the investigated time-span, the specific creep development over time was found to increase (i.e. soften) with increasing amount of fly ash. [ABSTRACT FROM AUTHOR]

By affecting the connectivity of atomic networks, composition, temperature, or pressure can induce topological transitions between the three atomic states of rigidity — flexible, isostatic, and stressed-rigid. However, no clear structural signature of such transitions has been elucidated thus far. Here, based on realistic molecular dynamics simulations of irradiation-induced damage in quartz, we report the first evidence of a rigid-to-flexible rigidity transition controlled by structural variations only. This topological transition is shown to arise from the simultaneous loss of atomic Eigenstress and onset of network flexibility, and features a well-defined structural signature in the medium-range order of the atomic network. [ABSTRACT FROM AUTHOR]

The authors report on the structural and optical property changes of alumina passivated amorphous Si slanted columnar thin films during electrochemical Li-ion intercalation and deintercalation determined by in situ generalized spectroscopic ellipsometry. The cyclic voltammetry investigations versus Li/Li+ are performed at a rate of 1mV/s, while Mueller matrix generalized spectroscopic ellipsometry data are collected. Through a best-match model analysis utilizing the homogeneous biaxial layer approach, temporal anisotropic optical constants are obtained. The authors observe a strong anisotropic electrochromic response with maximum changes of ∼18% in the anisotropic refractive indices and ∼750% in the anisotropic extinction coefficients. Furthermore, the thin films reversibly expand and contract by ∼35%. A comparative analysis of the temporal optical constant response to the changes in overall optical anisotropy of the electrode reveals six transient regions throughout the Li-ion intercalation and deintercalation cycle of the highly ordered three-dimensional nanostructures. The transients correspond to electrochemical potential regions which show limited charge transfer, metalization or demetalization and swelling or deswelling of the nanostructures. Furthermore, the electrochemical potential regions in which the transients are observed here are very similar to those previously reported for Li-ion intercalation and deintercalation of silicon nanowires using structural analysis techniques, where four distinct phases of Li-Si alloy formation were revealed. The authors find that at low Li contributions, swelling and deswelling occur preferentially along the slanted columns, while at high Li contributions, swelling and deswelling occur preferentially within the intercolumnar space. [ABSTRACT FROM AUTHOR]

A combined hydrothermal and sol-gel method has been developed to fabricate superhydrophobic coatings on zinc substrate. A double-layered structure of ZnO/SiO 2 nanorods and sub microtubes was obtained first on the surface of zinc substrate by the hydrothermal treatment. Then the effects of the Hexamethyldisiloxane (HMDS) and Tetraethoxysilane (TEOS) concentrations in the modification solution on the surface morphology, water repellency and corrosion resistance of the prepared surfaces were carefully studied. The results show that the water repellency of the surface depends largely on the molar ratio of HMDS/TEOS in the modification solution. When the molar ratio was 2, a layer of SiO 2 gel was deposited on ZnO nanorod-sub microtube structure to form ZnO/SiO 2 core/shell nanorod-sub microtube structure. The prepared superhydrophobic coating had a maximal water contact angle of 152° and a best corrosion resistance since the coating was unwetted in the corrosion solution and could prevent the corrosion media from penetrating into the zinc substrate. [ABSTRACT FROM AUTHOR]

In the present study, a method was developed for detection of Vibrio parahaemolyticus based on a stationary liquid phase lab-on-a-chip (SLP LOC). The present SLP LOC comprises a sample chamber, washing chamber, and detection chamber connected by two channels. The method utilizes two types of particles: capture particles (CPs), which are magnetic nanoparticles functionalized with antibody; and labeling particles (LPs), which are silica nanoparticles functionalized with horseradish peroxidase and antibody. Samples were added to the sample chamber with CPs and LPs, forming a CP-bacteria-LP complex, and the complex was transported to the detection chamber containing chromogenic substrate solution. The method allowed the detection of V. parahaemolyticus in the range of 10 1 –10 5 cfu within 45 min. Additionally, contamination of oyster samples with V. parahaemolyticus was detected within 2.5 h, including 2 h of culturing. The present method has the advantage of being highly rapid and facile, and enabling the detection of bacteria with high sensitivity. Moreover, the LOC and LOC processing device used in this method possess simple structures, making the detection process economical and allowing miniaturization. Therefore, the present SLP LOC detection method is potentially useful for in situ determination of food safety. [ABSTRACT FROM AUTHOR]

Isolation of a monomeric SiO2 compound 3 as a stable donor-acceptor complex with two different ligands -a σ-donating ligand (pyridine, dimethylaminopyridine, N-heterocyclic carbene) and a donor-acceptor ligand (iminophosphorane)-is presented. The SiO2 complex 3 is soluble in ordinary organic solvents and is stable at room temperature in solution and in the solid state. Of particular interest, 3 remains reactive and can be used as a stable and soluble unimolecular SiO2 reagent. [ABSTRACT FROM AUTHOR]

The sol-gel transition of silica-polyacrylamide hydrogel nanocomposites is studied when approaching the gel point by independently varying the nanoparticle (NP) and chemical crosslinker concentrations. Time-concentration-superposition (TCS) principles are applied to ascertain the effect of NPs on dynamics at the gel point. Doping dilute and concentrated polyacrylamide (PA) solutions with silica NPs indicates that these particles do not crosslink PA; neither do they form percolating networks. Nevertheless, silica NPs interact with PA to influence the storage and loss moduli to a much greater degree than expected for passive fillers. Interestingly, when silica NPs are embedded in very weakly chemically crosslinked PA (with a bis crosslinker concentration that would otherwise not form PA hydrogels), they significantly enhance the effective degree of crosslinking, forming viscoelastic solids. From TCS analysis of dynamics at the gel point, the bond probability is found to scale with the NP volume fraction as p ∼ ϕ 1.5 , whereas chemical crosslinking furnishes a bond probability that is linear in the crosslinker concentration. [ABSTRACT FROM AUTHOR]

Mesoporous silica based composites are widely used for humidity sensors. But a physical mixing is needed to load humidity sensitive materials in the mesoporous silica materials, so the uniform dispersion of humidity active materials could not be guaranteed. A chemically modification method has been used to ensure the uniform dispersion and stable structure of the humidity active units in this work. Novel organic-inorganic hybrid materials have been prepared via modifying the sulfhydryl functionalized mesoporous silica SBA-15 (SBA-15-propyl-SH) with hydrophilic unit methacrylatoethyl trimethyl ammonium chloride (DMC) via a thiol-ene click reaction. Mesoporous silica skeletons could ensure the stability at high humidities and hydrophilic groups modified on the skeletons behave as humidity sensitive parts. The content of DMC on the silica could be tuned by the feed ratios. The obtained hybrid materials keep the mesoporous characteristics of silica, which is beneficial for the transport of water molecules in adsorption and desorption processes. The humidity sensing properties of the sensors based on SBA-15-propyl-SH and SBA-15-propyl-S-DMCx were investigated in details. The impedance modulus of the optimized sensor changes by more than three orders of magnitude over the relative humidity (RH) range of 11% to 95%, with prompt response to RH change (11 s and 60 s for adsorption and desorption processes, respectively). [ABSTRACT FROM AUTHOR]

Green roofs are becoming increasingly common practice of the urban sustainable environment. The growing substrate is the most important part of green-roof technology. The cost of engineering substrates can be reduced by using locally available components. Since green roofs are a relatively new concept in Poland, there is a need to examine substrate compositions and characteristics, including commonly used ingredients as well as alternative recycled/waste materials. The aim of our study was to assess the ability of locally sourced waste materials as roof-growing media amendments. In the greenhouse experiment we tested two grass and herb species mixtures and four waste substrate formulas. The locally disposed waste materials used as components of growing media included silica wastes (byproducts of metallic ferrosilicon alloys), cellulose, foundry sand, and organic waste material removed from the organic horizons of mucky peat. The engineered Si-waste substrates were compared with the commercially available media. The physico-chemical properties of components and substrates, their stability over time, and the influence on plant growth and mineral nutrient status were examined. Particle size distribution, bulk density, mass, water capacity, soil reaction, and total dissolved salt content of Si-waste-growing media were compatible with FLL standards. We found low amounts of available P and K, and high concentrations of Ca, Mg, S, and trace elements (with the exception of B) in Si-waste substrates in comparison with the control media. Silica waste materials have the potential to maintain pH with high buffering capacity. Engineered Si-waste substrates had a positive impact on plant growth and biomass. In general, these results indicate that contaminant elements contained in alkaline Si-waste substrates were not easily available to the root system, and consequently they did not restrict plant growth. We consider Si-wastes to be a valuable and environmentally responsible green roof media amendment. [ABSTRACT FROM AUTHOR]

The burial efficiency of biogenic silica (BSi) in deltaic sediments is associated both with the nutrient balance in estuarine ecosystems and with the carbon cycle and climate change. To explore these relationships, foraminifera data, physical and chemical parameters, and ages determined by accelerator mass spectrometry 14C and optically stimulated luminescence from a core drilled at the southwestern edge of the Lower Liaohe Plain in May 2012 were presented. The sedimentary environments since 33,000 cal yr BP were divided into four depositional units, namely, a fluvial deposit (U1), lacustrine deposit (U2), marine-related deposit (U3), and upper delta plain deposit (U4). Environmentally mediated differences in apparent mass accumulation rates (AMARs) of BSi and organic carbon (Corg) were significant. The BSi-AMAR in the later parts of U1 and U2 occurred mainly in the Pleistocene and averaged 11.34 ± 0.22 and 16.69 ± 0.91 g m−2 yr−1, which is lower than the analogues for U3 (23.59 ± 2.89-41.74 ± 6.37 g m−2 yr−1) and U4 (37.25 ± 9.96 g m−2 yr−1) that occurred during the Holocene. The BSi record responded more coherently and was more sensitive than Corg to Northern Hemisphere paleoclimatic variations on a long timescale and to abrupt/periodic winter monsoon winds or warming forcings on a short timescale. There was a negative correlation between the concentration of bioavailable Fe2O3 and the ratio of BSi/Corg, the implication being that Fe availability may have modulated silicic acid uptake on a very short timescale and in turn impacted the dynamics of carbon burial. [ABSTRACT FROM AUTHOR]

Aggregation-induced luminescence quenching of carbon dots (CDots) is the main obstacle for their applications in the solid state. Herein, we report a method to produce strongly luminescent CDots@silica composite gels with highly concentrated emitting centers, where the gelation of tetraethyl orthosilicate is initiated by the surface hydroxyl groups of CDots. The key feature of this approach is to prevent both the collision between high concentrated CDots in gelating solution and their aggregation upon drying. The resultant CDots@silica composite xerogel exhibits both high CDots loading fraction (19.2 wt %) and photoluminescence quantum yields (>40%). [ABSTRACT FROM AUTHOR]

An enhanced one-pot synthesis of new functionalized 5,6-dihydro-5,5-dimethyl-2-phenyl-2 H -pyridazino[3,4,5- kl ]acridin-1(4 H )-one derivatives with different substituted patterns by using mesoporous MCM-41 catalyst via a ring opening/ring closure reaction process has been established. This MCM-41 silica catalyst has been synthesized and characterized using an array of sophisticated analytical techniques like BET, XRD, UHRTEM, etc. This reaction could be conducted from inexpensive substrates within short period under neat reflux conditions. Compared with the usual methods, the remarkable advantages of this method are milder reaction conditions, operational simplicity, higher yields, short reaction times and an environmentally friendly procedure. [ABSTRACT FROM AUTHOR]

Complex shaped nanoparticles featuring structural or surface chemical patchiness are of special interest in both fundamental and applied research areas. This study reports the preparation and optical properties of gold/silica 'mushroom' nanoparticles, where a gold particle is only partially covered by the silica cap. The synthetic approach allows precise control over the particle structure. The interfacial preparation method relies on partially embedding the gold particles in a polystyrene layer that masks the immersed part of the gold particle during silica shell growth from an aqueous solution. By adjusting sacrificial polystyrene film thickness and silica growth time, precise control over the coverage and cap thickness can be achieved. Correlative electron microscopy and single particle scattering spectroscopy measurements underline the high precision and reproducibility of the method. The good agreement between the measured and simulated single particle spectra supported by near-field calculations indicates that the observed changes in the dipolar plasmon resonance are influenced by the extent of coverage of the gold core by the silica cap. The straightforward methods readily available for gold and silica surface modification using range of different (bio)molecules make these well-defined nanoscale objects excellent candidates to study fundamental processes of programmed self-assembly or application as theranostic agents. [ABSTRACT FROM AUTHOR]

Copyright of Journal of China University of Petroleum is the property of China University of Petroleum and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

In order to improve the erosion capacity of a supercritical carbon dioxide (SC-CO2) jet, the influence of a nano-silica additive on the rock erosion characteristics was experimentally investigated. By impinging the SC-CO2 jets with nano-silica mass fractions of 0 wt % (pure SC-CO2 jet), 3 wt %, 6 wt %, 9 wt %, 12 wt %, 15 wt %, and 18 wt % on specimens of red sandstone, the erosion volumes under various operating conditions were measured and analyzed. Results show that an appropriate amount of nano-silica additive can greatly enhance the erosion ability of a SC-CO2 jet. The effect on the erosion ability largely depends on the operating conditions. For instance, when the other conditions are fixed, 6 wt %, 9 wt %, 12 wt %, and 15 wt % were the optimum mass fractions, successively, with the inlet pressure increasing from 30 MPa to 60 MPa. With the increase in ambient pressure, the optimum mass fraction is unchanged under the constant inlet pressure, while it increases under the constant pressure drop. Additionally, the optimum mass fraction decreases when the fluid temperature increases. In addition, the optimal standoff distances are about five times the nozzle diameter of the nano-silica SC-CO2 jet, and three times for the pure jet. This research provides a new method for effectively enhancing the rock erosion performance of a SC-CO2 jet. [ABSTRACT FROM AUTHOR]

We present a method for fabricating flexible nano-scale membranes using surface micromachining and silica thin films. Standard microfabrication techniques are used, and the membrane can be moved using electrostatic forces. The degree of deflection is set by an applied voltage, and the devices can be fully collapsed (100 nm movement) by applying approximately 150 V. Deflection tests were performed using an optical profilometer when the area under the membrane was filled with air and water. [ABSTRACT FROM AUTHOR]

Produced water is a by-product of oil and gas production. Once produced water is separated from oil (and gas) it is treated and then discharged to surface water or re-injected for either reservoir pressure maintenance or disposal. Here, we prepared mesoporous silica (MCM-41) by simple single step method and characterized by XRD, FTIR, Raman, N2 adsorption-desorption and TEM. Then, a continuous fixed bed study was carried out using a prepared MCM-41 for oil removal from produced water. The effects of flow rate and bed height on the breakthrough characteristics of the adsorption system were determined. XRD analysis of the silica powder showed complete formation of a single phase mesoporous MCM-41 without contamination of other phases of silica. The maximum removal (70.26%) was achieved for a flow rate of 0.5 mL/min and a bed height of 1.5 mm. Two models Thomas and Yoon-Nelson were applied to predict the breakthrough curves. The results show that Thomas model fitted well the adsorption data with a correlation coefficient (R2) at different conditions. R2 values suggested that the suitable model for describing the chemisorption oil on MCM-41 was Thomas model. The model showed that the MCM-41 was suitable adsorbent for oil using fixed bed adsorption. [ABSTRACT FROM AUTHOR]

In this paper, we present the design and experimental demonstration of a broad single-band metamaterial absorber composed of a simple two-dimensional periodic silver-SiO 2 -silver sandwich array. The experimental results show that a near-perfect absorption band with a bandwidth of approximately 0.4 μm in the THz region is obtained, which is in reasonable agreement with the simulated results. The calculated electric field intensity distributions indicate that the broad absorption band is achieved by plasmonic hybridization of two plasmon resonances: one originates from outward coupling between adjacent unit cells and the other arises from inward coupling between the two sub-structures. The effects of the structural parameters and the SiO 2 layer thickness on the broad absorption band are investigated experimentally. The effect of the angle of incidence on the broad absorption band is also investigated experimentally and the absorption band remains high at large angles of incidence (60°), which thus provides more efficient absorption of obliquely incident beams. [ABSTRACT FROM AUTHOR]

Fluorocarbon stationary phases have taken great advances in recent years in liquid chromatography. Numerous studies to elucidate the retention mechanism have been undertaken that concluded the retention is driven by a multitude of factors, due to the presence of fluorine atoms in the molecule. Many applications in this domain have been described in the literature so far. Applications for other fields have also been published in various original papers for fluorocarbon silica. [ABSTRACT FROM AUTHOR]

An isotope dilution congener-specific method for the determination of the most abundant and most toxic polychlorinated naphthalenes (PCNs) was developed using gas chromatography with high resolution mass spectrometry (GC-HRMS). The method was used to determine the concentration of 24 target congeners and total PCN concentrations in fish and sediment samples. Tissue samples were extracted using pressurized liquid extraction (PLE) and sediment samples were extracted using Soxhlet extraction. Sample extracts were cleaned up using either a manual two-stage open column procedure or an automated FMS Power Prep System with multi-analyte and multi-sample capability using a three-column cleanup procedure. Sediment extracts were cleaned up with a dual open column cleanup technique involving the use of both a multi-layered silica (silver nitrate/acid/base/neutral silica) column followed by column containing carbon-activated silica. Fish tissue extracts were cleaned up on the automated system involving the use of a high capacity ABN (acid/base/neutral column), carbon celite column, and a basic alumina column. The method is capable of producing instrument detection limits (IDLs) between 0.06 and 0.13 pg for each PCN (on column), with method detection limits (MDLs) for the fish extracts ranging from 1.3 to 3.4 pg/g (wet weight) and 0.46 to 1.2 pg/g (dry weight) for sediments. The average accuracy of 34 spiked fish samples analysed over a period of several months was 100% with a precision (%RSD) of 12%. Similarly, the average accuracy for 28 spiked sediment samples was 104% with a precision (%RSD) of 12%. The application of the method to environmental samples was demonstrated through the analysis of sediment and fish samples obtained from Lake Ontario, Canada. The method is used both for the determination of 24 PCNs and to perform non-targeted screening for the remaining 51 PCN congeners, which are included in the total PCN quantification result. It is currently one of the most comprehensive and accurate congener-specific methods available and was developed from the existing techniques used for the determination of polychlorinated dioxins and furans to produce high quality data with only minor modifications in the clean-up procedure. It can therefore be readily adopted by other laboratories performing dioxin and POP analyses. [ABSTRACT FROM AUTHOR]

The report presents a technological scheme of complex processing of man-made waste of phosphorus production - slag to produce highly dispersed silicon dioxide and a rare-earth metal concentrate. The technological parameters of each operation of the technology are chosen. Recovery of rare-earth metals from phosphorus slags during various operations was, %: leaching -- 95.0; extraction - 90.2; stripping on the average ~ 93.2; the production of ∑ REM oxide concentrate is 93.9. The composition of some batches of "white soot" obtained during processing of the technological scheme is shown. [ABSTRACT FROM AUTHOR]

Well dispersed mono and coupled NiO, ZnO oxides modified silica, with a narrow size distribution, less than 10 nm, have been synthesized by “one–pot” microemulsion assisted sol–gel procedure. The composites exhibited significantly enhanced tandem adsorption–photodegradation activity for the degradation of Methylene Blue dye over 90% (under UV light) and 97% (under sun light). These highly homogeneous oxides modified silica, with very low content of NiO (0.01÷1.14%) and ZnO (0.09%) oxides dispersed in silica, are generating a size effect that leads to nanomaterials with superior properties like higher specific surface area (308 m 2 g −1 ), smaller band-gaps energy (2.5 eV) and, consequently, extended light absorption range from UV to natural light. A synergistic effect of mixed n –type ZnO and p –type NiO oxides incorporated in silica has been noticed on the tandem adsorption and photodegradation process. Several influencing process parameters, such as the material and dye loading, stirring speed, NiO/ZnO ratio and light source on the photodegradation performance of NiO-ZnO modified silica related to Methylene Blue cationic dye, were also investigated. [ABSTRACT FROM AUTHOR]

The effect of 3-methacryloxypropyltrimethoxysilane (MPTMOS) on the nucleation of silica particles synthesized in a water−ethanol−ammonia−tetraethoxysilane (TEOS) mixture by the Stöber−Fink−Bohn method has been studied. It has been shown, using atomic force microscopy, that, as the content of MPTMOS in a TEOS + MPTMOS precursor mixture is increased from 0 to 12.5 mol %, the final silica particle size decreases from 470 to 10 nm, because the number of nucleation centers increases by several orders of magnitude. In contrast to TEOS, hydrolysis of MPTMOS yields a smaller amount of deprotonated orthosilicic acid monomers, the condensation of which is hindered by electrostatic repulsion. The polycondensation of electrically neutral products of MPTMOS hydrolysis gives rise to a larger number of nucleation centers in the reaction mixture. [ABSTRACT FROM AUTHOR]

Adsorbents based on silica sequentially modified by polyhexamethylene guanidine and nitroso-R salt or nitroso-N salt are proposed for the preconcentration and adsorption-photometric determination of iron. It is shown that these adsorbents quantitatively recovered Fe(III) at pH 3.5-4.0 and Fe(II) at pH 4.5-7.0. In the adsorption of Fe(III) and Fe(II), intensely colored green complexes formed on the adsorbent surface. Based on the absence of signals in EPR spectra, it was concluded that iron in the oxidation state +2 was included into surface complexes with nitroso-R salt or nitroso-N salt. When Fe(III) interacted with nitroso-R salt or nitroso-N salt immobilized on the adsorbent surface, it was reduced to Fe(II). Diffuse reflection spectra of the surface complexes of iron(II) were broad bands with maxima at 720 and 710 nm. Procedures of the adsorption-photometric determination of iron in natural waters and snow samples were developed with the limit of detection of 0.05 μg of iron per 0.2 g of the adsorbent. [ABSTRACT FROM AUTHOR]

Montmorillonite with dimethyl di(hydrogenatedtalloyl) ammonium as the compensating cation was added to a silica based elastomeric composite and the hybrid filler system led to reduction of filler networking phenomenon, better stability of elastic modulus with temperature, enhancement of stresses at all elongations, improvement of ultimate properties. This composite was based on a blend of natural rubber, poly(1,4- cis- isoprene) and poly(styrene- co -butadiene) from anionic polymerization and contained 70 parts per hundred rubber (phr) of silica. The organically modified clay (OC) was below the threshold required to establish an hybrid OC-silica filler network. Such threshold (about 7 phr) was estimated by preparing silica based nanocomposites containing various amounts of OC and determining shear storage and loss moduli as a function of strain amplitude. This work demonstrates that exfoliated OC favour lower dissipation of energy of silica based elastomeric composites under dynamic mechanical stresses and paves the way for further large scale applications. [ABSTRACT FROM AUTHOR]

The influence of polyvinylpyrrolidone (PVP) adsorption on the silica suspension stability was studied. The effects of silica content, polymer addition and suspension dilution with water were examined. The turbidimetry method was applied to examine stability of the investigated systems as a function of time. It was shown that the suspension without polymer was characterized by the smallest stability, whereas the systems containing PVP (before and after dilution) are successively stable. The specific conformation of PVP chains on the solid surface is responsible for the stabilization-flocculation properties of PVP in the colloidal suspension. [ABSTRACT FROM AUTHOR]

The system constants of the solvation parameter model are used to prepare system maps for the retention of small neutral compounds on a biphenylsiloxane-bonded superficially porous silica stationary phase (Kinetex Biphenyl) for aqueous-organic solvent mobile phases containing 10–70% (v/v) methanol or acetonitrile. The retention properties of the biphenylsiloxane-bonded phase are shown to be complementary to an octadecylsiloxane-bonded silica (Kinetex C-18) and a pentafluorophenylpropylsiloxane-bonded silica stationary phases (Discovery HS F5). The retention properties of the Kinetex Biphenyl column are similar to an ether-linked phenylpropylsiloxane-bonded silica phase (Synergi Polar RP) with only small differences in relative retention. [ABSTRACT FROM AUTHOR]

An in-depth understanding about the transformation of molten coke ash is significant to uncover the mechanism of coke reaction at high temperature inside a blast furnace. The evolution of local structural order and fluidity of molten coke ash (SiO 2 -Al 2 O 3 -CaO) with the reduction of SiO 2 at a fixed Al 2 O 3 /CaO ratio was investigated by means of molecular dynamics (MD) simulation. While [SiO 4 ] tetrahedral was the main structural units forming Si-O network, due to the high levels of Al 2 O 3 in coke minerals [AlO 4 ] and a small amount of [AlO 5 ] were the two key structural units forming the Al-O network. The effect of chemical composition on the bond length of Si-O, Al-O and Ca-O is very weak, while the coordination number of Al-O can be slightly influenced by the reduction of SiO 2 due to the unstable structure of Al-centered polyhedron compared with [SiO 4 ]. The concentration of bridging oxygen decreases, while that of tricluster oxygen increases with the reduction of SiO 2 from the system. Al-centered polyhedrons prefer to be connected by O triclusters, while Si-centered polyhedron favor a link by bridging oxygen. With the decrease of SiO 2 , more [AlO 4 ] will change from edge-sharing to corner-sharing with similar units. The angular distribution of Si-O-Si exhibits an asymmetric shape with the average value around 151°, while two peaks were observed in the Al-O-Al angular distribution because of the edge-sharing (∼90°) and corner-sharing (∼122°) features in Al-centered polyhedrons. With the reduction of SiO 2 from the system, the diffusivity of all atoms increase considerably since the amount of strong Si-O bond decreases. Viscosity estimated from MD simulation decrease with the reduction of SiO 2 . The good agreement between MD simulated data and experimental data indicates that MD simulation can be adopted to estimate the property change of molten coke ash at high temperature. [ABSTRACT FROM AUTHOR]

A 100 mm-diameter split Hopkinson pressure bar (SHPB) was applied to investigate effects of nanoparticles on the dynamic mechanical properties of recycled aggregate concrete (RAC) under impact loading. The nano-SiO 2 (NS) and nano-CaCO 3 (NC) were incorporated to replace cement by mass of 1 and 2% in RACs. The impact velocities were set as 7.7, 9.8 and 11.6 m/s in the SHPB tests. The effects of nanoparticles on failure patterns, compressive strengths, elastic modulus, peak strain and dynamic increase factor (DIF) of RACs under different strain rates were analyzed and discussed. The results show that nanomodified RACs exhibit higher both quasi-static and dynamic compressive strengths compared to control RAC. Dynamic elastic modulus of RAC seems not be affected by nanoparticle dosages and impact velocities. Compared to NC, NS is more effective to improve dynamic compressive strengths of RAC. On the other hand, the nanoparticles modified RACs exhibit lower DIF values than that of the control RAC. Moreover, NC obviously more reduces the DIF values of nanomodified RAC than NS. [ABSTRACT FROM AUTHOR]

A major obstacle to the hydrometallurgical treatment of ferromanganese slags is the way in which silica polymerisation is controlled during sulphuric acid digestion and water leaching. In an acidic medium, silica enters in solution and forms silicic acid, which polymerises into silica gel and makes solid-liquid separation difficult. This article will show that the quick leach model, also called the water-starved system, limits silica solubilisation and its subsequent polymerisation during manganese extraction from ferromanganese slags by rejecting most of the ferromanganese slag silica content in the leach residue. It will further illustrate that the silica content in the residue is dependent on the acid concentration used during acid digestion. It will also show that dissolved silica in the pregnant leach solution is high when an unrestricted quantity of water is used and low when the water quantity is restricted during water leaching. Furthermore, a method for silica gel recovery from ferromanganese slag will be presented, as well as the silica gel analysis, in order to confirm the theory presented in this article. Manganese extraction of up to 90% is obtained and the leach residue presents good latent hydraulic properties, which can be used as an addition to Portland cement or a gypsum replacement. More than 95% of the initial silica content of the slag is rejected in the leach residue, and a residue silica content of more than 27% is obtained. Thus, silica solubilisation and polymerisation are controlled and solid-liquid separation is accelerated. [ABSTRACT FROM AUTHOR]

The influence of SiO 2 nanoparticles on hydrophobicity and the corrosion protection capabilities of hybrid acrylic-silicone polymeric matrix have been investigated. Contact angle measurements (CA), atomic force microscopy (AFM), field emission scanning electron microscopy (FE-SEM), and energy dispersive X-ray spectroscopy (EDX) were used to study the hydrophobicity, morphology, and topography of the coatings. In addition, electrochemical impedance spectroscopy (EIS) and salt spray techniques were employed to evaluate the corrosion protection performance. A coating with 3 wt.% SiO 2 , AS 3, demonstrates significant improvement in corrosion resistance with the highest measured CA of 97.3°. Morphology and topography studies clarify the influence of nano-sized SiO 2 fillers on the surface topography and demonstrated the uniform and good distribution of the embedded SiO 2 nanoparticles within the polymeric matrix. [ABSTRACT FROM AUTHOR]

Due to the major role played by diatoms in the marine biological pump, opal/biogenic silica (bSi) has a strong potential as a proxy for paleoproduction reconstructions. Here, we present a detailed evaluation of the independent Fourier transform infrared spectroscopy (FTIRS) calibration introduced by Meyer-Jacob et al. (2014 a), which is based on synthetic sediment mixtures with known concentrations of bSi and the application of partial least squares (PLS) regression, for the determination of bSi in marine sediments. To test the robustness of the FTIRS calibration for marine samples we selected 199 globally distributed samples, with available wet chemically inferred bSi concentrations and compared the results of both methods. We observe that the spectral characteristics in marine samples are comparable to those reported for a synthetic FTIR spectrum composed solely of spectral features in quartz, biogenic silica, and calcite. FTIRS-inferred and wet-chemically measured bSi concentrations for the set of 199 marine sediment samples are strongly correlated ( R2 = 0.87; RMSE = 5.27%). Together with the high reproducibility of bSi values by the independent calibration our results corroborate the applicability of the independent FTIRS bSi calibration for quantification in marine samples. This together with the succinct sample preparation procedure, rapid analysis, reduced consumable and machine maintenance costs makes FTIRS a powerful and robust alternative for the quantitative analysis of bSi in marine sediments. [ABSTRACT FROM AUTHOR]