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Background/Aim: The role of senescence and bone marrow-derived cells in silica-induced pulmonary fibrosis is unknown. Materials and Methods: C57BL/6HNsd, p16+/LUC, and tdTOMp16+ mice were intratracheally injected with 200 mg/kg crystalline silica or irradiated (20 Gy) to the thoracic cavity and followed for the development of lung fibrosis. Results: The p16+/LUC mice demonstrated senescence by day 7 after silica exposure. C57BL/6 mice exposed to silica demonstrated upregulation of p16, p21, and tyrosine kinase Fgr by day 7, whereas thoracic irradiation induced p21 and Fgr by day 50 and p16 by day 110. Silica exposed GFP+ bone marrow chimeric C57BL/6 mice demonstrated senescent cells and gfp+/Fgr+ monocyte/macrophages in the lungs on day 21. The Fgr inhibitor TL02-59 abrogated monocyte/macrophages recruitment in in vitro transwell experiments. Conclusion: Both silica and radiation exposure induce senescence and upregulate tyrosine kinase Fgr for the recruitment of bone marrow-derived monocyte/macrophages and the development of pulmonary fibrosis. [ABSTRACT FROM AUTHOR]

Background: While the association between occupational inhalation of silica dust and pulmonary tuberculosis has been known for over a century, there has never been a published systematic review, particularly of experience in the current era of less severe silicosis and treatable tuberculosis. We undertook a systematic review of the evidence for the association between (1) silicosis and pulmonary tuberculosis, and (2) silica exposure and pulmonary tuberculosis controlling for silicosis, and their respective exposure-response gradients.Methods: We searched PUBMED and EMBASE, and selected studies according to a priori inclusion criteria. We extracted, summarised and pooled the results of published case-control and cohort studies of silica exposure and/or silicosis and incident active tuberculosis. Study quality was assessed on the Newcastle-Ottawa Scale. Where meta-analysis was possible, effect estimates were pooled using inverse-variance weighted random-effects models. Otherwise narrative and graphic synthesis was undertaken. Confidence regarding overall effect estimates was assessed using the GRADE schema.Results: Nine studies met the inclusion criteria. Meta-analysis of eight studies of silicosis and tuberculosis yielded a pooled relative risk of 4.01 (95% confidence interval (CI) 2.88, 5.58). Exposure-response gradients were strong with a low silicosis severity threshold for increased risk. Our GRADE assessment was high confidence in a strong association. Meta-analysis of five studies of silica exposure controlling for or excluding silicosis yielded a pooled relative risk of 1.92 (95% CI 1.36, 2.73). Exposure-response gradients were observable in individual studies but not finely stratified enough to infer an exposure threshold. Our GRADE assessment was low confidence in the estimated effect owing to inconsistency and use of proxies for silica exposure.Conclusions: The evidence is robust for a strongly elevated risk of tuberculosis with radiological silicosis, with a low disease severity threshold. The effect estimate is more uncertain for silica exposure without radiological silicosis. Research is needed, particularly cohort studies measuring silica exposure in different settings, to characterise the effect more accurately as well as the silica exposure threshold that could be used to prevent excess tuberculosis risk. [ABSTRACT FROM AUTHOR]

The objective of the current study was to design a suitable model to predict the cytotoxicity induced by SiO2 and TiO2 nanoparticles in different conditions using computational models. To achieve this, we employed various statistical approaches such as linear regression, as well as artificial neural networks and support vector machine (nonlinear models). The effective input parameters of the SiO2 nanoparticles were particle size, particle concentration, and cell exposure time. In the case of the TiO2 nanoparticles, the particle size and concentration served as input variables. Cell viability was considered the output response for both nanoparticles. The modeling was performed using both linear and non-linear methods. In addition, an external validation analysis was conducted to evaluate the predictability of the models by splitting the data into training and test data. The best models to predict cell viability were the models developed by artificial neural network. The results of this investigation indicate that non-linear models could be superior to linear models in predicting cell viability for SiO2 and TiO2 nanoparticles. [ABSTRACT FROM AUTHOR]

Silicosis is one of the typical forms of pneumoconiosis characterized by abnormal proliferation of fibroblasts and deposition of extracellular matrix. Recent findings have shown that microRNAs and circular RNAs (circRNAs) are implicated in many diseases. However, the function of noncoding RNAs in pulmonary fibrosis remain to be elucidated. Here, miR-7 was found significantly decreased in silica-treated pulmonary epithelial cells as well as in fibrotic lung tissues of mice. Elevated expression of miR-7 via agomir injection relieved lung fibrosis in vivo. Further molecular study showed that miR-7 played its role against pulmonary fibrosis by blocking epithelial-mesenchymal transition (EMT) progression of human bronchial epithelial cells and A549 cells. Notably, transforming growth factor beta receptor 2 (TGFBR2) was identified as a target gene of miR-7 with bioinformatics tools, which was verified by dual luciferase receptor gene assay in human bronchial epithelial cells and A549 cells. Silica induced elevation of TGFBR2 could be abolished by exogenous expression of miR-7. Furthermore, bioinformatics software indicated that circRNA CDR1as had several binding sites for miR-7. The inhibitory effects of miR-7 on EMT and its target TGFBR2 were suppressed by circRNA CDR1as, which contributed to pulmonary fibrosis. Our studies also revealed overexpressed miR-7 could repress fibrogenesis of lung fibroblasts induced by TGF-β1. Collectively, circRNA CDR1as stimulated by silica could sponge miR-7 to release TGFBR2, plays an important role during pulmonary fibrosis by promoting EMT process. These results indicated that the interaction between miR-7 and circRNA CDR1as may exert important functions and provide potential therapeutic targets in lung fibrotic diseases. [ABSTRACT FROM AUTHOR]

Silicosis is caused by exposure to crystalline silica (CS). We have previously shown that blocking 4-1BB signaling attenuated CS-induced inflammation and pulmonary fibrosis. However, the cells that express 4-1BB, which plays a vital role in promoting fibrosis, are still unknown. In this study, we demonstrated that the expression of 4-1BB is elevated in alveolar macrophages (AMs) in the lungs of CS-injured mice. CS exposure also markedly enhanced the expression of 4-1BB in macrophage-like, MH-S cells. In these cells, activation of the 4-1BB signaling with an agonist antibody led to upregulated secretion of pro-fibrotic mediators. Consistently, blocking 4-1BB downstream signaling or genetic deletion of 4-1BB alleviated pro-fibrotic responses in vitro , while treatment with a 4-1BB fusion protein promoted pro-fibrotic responses. In vivo experiments showed that blocking 4-1BB signaling decreased the expressions of pro-fibrotic mediators and fibrosis. These data suggest that 4-1BB signaling plays an important role in promoting AMs-mediated pro-fibrotic responses and pulmonary fibrosis. Our findings may provide a potential molecular target to reduce CS-induced fibrotic responses in occupational lung disease. [ABSTRACT FROM AUTHOR]

Contrary to previous linear projections of steel corrosion in seawater, analysis of an inert marker embedded in USS Arizona concretion since the 7 December 1941 attack on Pearl Harbor reveals evidence that the effective corrosion rate decreases with time. The secant rate of corrosion, or SRC correlation, derived from this discovery could have a significant impact on failure analysis investigations for concreted shipwrecks or underwater structures. The correlation yields a lower rate of metal thinning than predicted. Development of the correlation is described. [ABSTRACT FROM AUTHOR]

This paper presents a facile and efficient synthesis method to fabricate epoxy-acrylate copolymer/nano-silica latex via Pickering emulsion polymerization stabilized by silica sol. The effects of solid contents, silica concentration and polymerization time on emulsion polymerization were studied. The core-shell epoxy-acrylate copolymer/nano-silica was obtained with average diameter 690 nm, was observed by Transmission Electron Microscopy (TEM) and Dynamic Light Scattering (DLS). The formation mechanism of epoxy-acrylate copolymer/nano-silica emulsion polymerization was proposed through observing the morphology of latex particles at different polymerization time. Fourier Transformation Infrared (FT-IR) and Thermogravimetric Analysis (TGA) were used to study structure and thermostability of the composites. Morphology of the latex film was characterized by Scanning Electron Microscope (SEM). The results indicated that nano-silica particles existed in the composite emulsion and could improve the thermal stability of the film. The epoxy-acrylate copolymer/nano-silica latex was used as binder applied to cotton fabric for pigment printing. The application results demonstrated that Pickering emulsion stabilized by silica sol has good effects in the pigment printing binder without surfactant. Compared with commodity binder, the resistance to wet rubbing fastness and soaping fastness were improved half grade. [ABSTRACT FROM AUTHOR]

Sr and Tm co-doped Ba 0.7 Sr 0.3 Ti 0.9925 Tm 0.01 O 3 (BST) and core-shell structured BST@SiO 2 ceramics were prepared by sol-gel method and conventional sintering. Along with the obvious perovskite phases in the BST and BST@SiO 2 powders, a new phase, Ba 2 TiSi 2 O 8 , was confirmed in the sintered BST@SiO 2 bulk by XRD analysis. TEM analysis revealed that the BST powders were coated with an amorphous SiO 2 film, while SEM analysis indicated that the SiO 2 film plays a role in grain size reduction. The dielectric losses of BST@SiO 2 ceramics reduced effectively compared to that of BST. In addition, the Curie peak of the BST@1%SiO 2 ceramic significantly broadened and the Curie temperature shifted toward lower temperatures; this provides a new approach to improving the dielectric properties of BaTiO 3 ceramics. [ABSTRACT FROM AUTHOR]

In vitro prediction of inflammatory lung effects of well-dispersed nanomaterials is challenging. Here, the in vitro effects of four colloidal amorphous SiO2 nanomaterials that differed only by their primary particle size (9, 15, 30, and 55 nm) were analyzed using the rat NR8383 alveolar macrophage (AM) assay. Data were compared to effects of single doses of 15 nm and 55 nm SiO2 intratracheally instilled in rat lungs. In vitro, all four elicited the release of concentration-dependent lactate dehydrogenase, β-glucuronidase, and tumor necrosis factor alpha, and the two smaller materials also released H2O2. All effects were size-dependent. Since the colloidal SiO2 remained well-dispersed in serum-free in vitro conditions, effective particle concentrations reaching the cells were estimated using different models. Evaluating the effective concentration-based in vitro effects using the Decision-making framework for the grouping and testing of nanomaterials, all four nanomaterials were assigned as "active." This assignment and the size dependency of effects were consistent with the outcomes of intratracheal instillation studies and available short-term rat inhalation data for 15 nm SiO2. The study confirms the applicability of the NR8383 AM assay to assessing colloidal SiO2 but underlines the need to estimate and consider the effective concentration of such well-dispersed test materials. [ABSTRACT FROM AUTHOR]

Objectives: Workers in the mining industry in altitude are subjected to several risk factors, e.g., airborne silica and low barometric pressure. The aim of this study has been to assess the risks for this work category, evaluating single risk factors as airborne silica, altitude and work shift, and relating them with cardiovascular and ventilatory parameters.Material and Methods: Healthy miners employed in a mining company, Chile, working at varied altitudes, and subjected to unusual work shifts, were evaluated. Cardiovascular and respiratory parameters were investigated. Exposure to airborne silica was evaluated and compared to currently binding exposure limits.Results: At varied altitudes and work shifts, alterations emerged in haemoglobin, ventilation and respiratory parameters, related to employment duration, due to compensatory mechanisms for hypoxia. Haemoglobin increased with altitude, saturation fell down under 90% in the highest mines. The multiple linear regression analysis showed a direct relationship, in the higher mine, between years of exposure to altitude and increased forced vital capacity percent (FVC%), and forced expiratory volume in 1 s (FEV1). An inverse relationship emerged between forced vital capacity (FVC) and years of exposure to airborne silica. In the workplace Mina Subterrànea (MT-3600), statistically significant inverse relationship emerged between the Tiffeneau index and body weight.Conclusions: The working conditions in the mining industry in altitude appeared to be potentially pathogenic; further investigations should be realized integrating risk assessment protocols even in consideration of their undeniable unconventionality. Int J Occup Med Environ Health 2018;31(2):129-138. [ABSTRACT FROM AUTHOR]

In vitro prediction of inflammatory lung effects of well-dispersed nanomaterials is challenging. Here, the in vitro effects of four colloidal amorphous SiO2 nanomaterials that differed only by their primary particle size (9, 15, 30, and 55 nm) were analyzed using the rat NR8383 alveolar macrophage (AM) assay. Data were compared to effects of single doses of 15 nm and 55 nm SiO2 intratracheally instilled in rat lungs. In vitro, all four elicited the release of concentration-dependent lactate dehydrogenase, β-glucuronidase, and tumor necrosis factor alpha, and the two smaller materials also released H2O2. All effects were size-dependent. Since the colloidal SiO2 remained well-dispersed in serum-free in vitro conditions, effective particle concentrations reaching the cells were estimated using different models. Evaluating the effective concentration-based in vitro effects using the Decision-making framework for the grouping and testing of nanomaterials, all four nanomaterials were assigned as "active." This assignment and the size dependency of effects were consistent with the outcomes of intratracheal instillation studies and available short-term rat inhalation data for 15 nm SiO2. The study confirms the applicability of the NR8383 AM assay to assessing colloidal SiO2 but underlines the need to estimate and consider the effective concentration of such well-dispersed test materials. [ABSTRACT FROM AUTHOR]

The present study provides a comprehensive investigation at the micro and nanoscale of the interface between hybrid SiO 2 @POSS nanofiller, where silica nanoparticles (NPs) and POSS nanocages are intimately interconnected, and Styrene Butadiene Rubber (SBR). SEM and AFM inspection and, more in depth, solid state 1 H NMR revealed a remarkable fraction of rigid rubber close to the SiO 2 @POSS surfaces, which increases with the curing temperature. Instead, a reduced amount of immobilized rubber was detected for SBR/SiO 2 +POSS nanocomposites, obtained by simply mixing SBR, SiO 2 and POSS. The results allowed us to propose a model for the network formation in C-SBR/SiO 2 @POSS. This is based on the progressive activation by dicumylperoxide (DCP) of the methacryl functionalities of POSS nanounits which, being closely connected to SiO 2 NPs in SiO 2 @POSS, promote crosslinking in proximity of the filler surfaces, and lead to the generation of a tight network strongly bonded to the rubber chains. [ABSTRACT FROM AUTHOR]

Crystalline silica has been classified as a definite carcinogen (Group 1) causing lung cancer by the International Agency for Research on Cancer (IARC). In Korea, crystalline silica has been the most common causal agent for workers to apply to the Korea Workers' Compensation and Welfare Service (KWCWS). We used KWCWS data to evaluate workers' crystalline silica exposure levels according to their occupations and industries, and reviewed research papers describing the dose-response relationship between cumulative exposure levels and lung cancer incidence. In addition, we reviewed lung cancer cases accepted by the KWCWS, and suggest new criteria for defining occupational cancer caused by crystalline silica in Korea. Rather than confining to miners, we propose recognizing occupational lung cancer whenever workers with pneumoconiosis develop lung cancer, regardless of their industry. Simultaneous exposure and lag time should also be considered in evaluations of work-relatedness. [ABSTRACT FROM AUTHOR]

It is known that ceramic workers are potentially exposed to complex mixture of chemicals such as silica, inorganic lead, lime, beryllium and aluminum that can be associated with an increased risk of several diseases. All operations in the ceramic industries such as mixing, moulding, casting, shaking out and finishing jobs, have been associated with the higher exposure levels and in most of the silica-related industries, average overall exposure exceeded permissible exposure levels for respirable crystalline silica. The aim of this study was to evaluate the possible genotoxic damage in ceramic workers exposed to complex mixture of chemicals mainly crystalline silica. For this purpose, the blood and buccal epithelial cell samples were taken from the ceramic workers (n = 99) and their controls (n = 81). The genotoxicity was assessed by the alkaline comet assay in isolated lymphocytes and whole blood. Micronucleus (MN), binucleated (BN), pyknotic (PYC), condensed chromatin (CC), karyolytic (KYL), karyorrhectic (KHC) and nuclear bud (NBUD) frequencies in buccal epithelial cells and plasma 8-oxo-7,8-dihydro-2'-deoxyguanosine (8-oxodG) levels were also evaluated. In the study, 38 workers were diagnosed with silicosis, 9 workers were suspected to have silicosis, whereas 52 workers were found to be healthy. DNA damage in blood and lymphocytes; MN, CC+ KHC, PYC frequencies in buccal epithelial cells and 8-oxodG levels in plasma were increased in workers compared to their controls. These results showed that occupational chemical mixture exposure in ceramic industry may cause genotoxic damage that can lead to important health problems in the workers. [ABSTRACT FROM AUTHOR]

The effects of holding time in Bridgman furnace on mechanical properties of injection molded silica-based ceramic cores for directional solidification of SX superalloy have been investigated. The cylindrical samples (S0) were sintered at 1000 ℃ for 60 min, and some of the sintered samples (S1, S2, S3) were treated by heat treatment at 1500 ℃ to simulate the directional solidification process. Isothermal uniaxial compression tests of ceramic core samples were conducted on a Gleeble-1500D mechanical simulator. Weibull approach was used to describe the strength distribution of silica-based ceramic cores. As a result, the mean compressive strength of the sample (S0) is 40.43 MPa. The mean compressive strengths of the samples (S1, S2, S3) with heat treatment at 1500 ℃ are 54.34 MPa, 53.60 MPa and 53.81 MPa, respectively, which are significantly larger than that of S0. The mean elastic moduli of the samples (S1, S2, S3) with heat treatment at 1500 ℃ are 2726.39 MPa, 2855.91 MPa and 2797.14 MPa, respectively, which is significantly higher than that of S0. The refractory particle evolution of the ceramic core during the directional solidification process is analyzed, and the microstructural investigations show that the crack propagation of ceramic core sintered at 1000 ℃ is mainly through the sintering necks between particles. However, the crack propagation of ceramic core holding at 1500 ℃ is extended through the entire large particles. The re-sintering process of ceramic core holding at 1500 ℃ compensates the negative effect of cracks due to the volume contraction during β- to α-phase transformation and the rapid cooling process, and improves the ceramic core uniformity and mechanical properties. [ABSTRACT FROM AUTHOR]

Background: The use of colloidal silica contained in different cryopellet formulations is examined as a contact activator of blood in an intrinsic coagulation test. In particular the necessary amount of silica per cryopellet was determined, as well as the interfering effects of cryopellet components on coagulation. Methods: Cryopellets were prepared using an established technique and were tested by rotational thromboelastometry using recalcified whole blood. The clotting time (CT) and maximum clot firmness (MCF) were determined from the dynamic coagulation profiles. Results: Levels of silica of 25 - 75 ìg per cryopellet weight of 1.25 mg reduced CT to below 200 seconds and gave good MCF. Trehalose had no effects of coagulation, whereas mannitol reduced CT by a third. The incorporation of silica in the liquid feed used for cryopelletization did not inhibit uniformity of droplet and hence cryopellet weight. The activating activity of the silica [CT and MCF] was the same as that of a classic intrinsic assay using ellagic acid. Conclusions: A silica-containing cryopellet can be prepared and works as well as ellagic acid as an activator in intrinsic rotational thromboelastometry. A cryopellet avoids dilution of the whole blood sample and hence also of coagulation-relevant blood components that can alter the coagulation result. [ABSTRACT FROM AUTHOR]

A novel C/SiO 2 /SiC ternary aerogel is derived from catechol-formaldehyde/silica hybrid aerogel (CF/SiO 2 ) via a one-step sol-gel method followed by carbonization and carbothermal reduction processes under flowing argon. The effects of the carbon/silica molar ratios on the physicochemical properties of the C/SiO 2 binary and C/SiO 2 /SiC ternary aerogel are investigated. The mechanism of the textural and structural evolution for the novel C/SiO 2 /SiC ternary aerogel is further discussed based on the experimental results and the calculated Gibbs free energy changes at different SiO partial pressure. The SiC layer is first formed on the surface of the composite aerogel via the solid-vapor reaction at 1400 °C while SiC nanoparticles form at 1500 °C. The C/SiO 2 /SiC ternary aerogel possesses a rather high specific surface area (746.87 m 2 /g), a high micropore volume (0.2279 cm 3 /g) and a high porosity (89.10%). The oxidation resistance is improved for 100 °C when compared with the carbon based aerogel. The ternary aerogel obtains a high compressive strength (1.86 MPa) and a low thermal conductivity (0.053 W/m*K), which is suitable for high efficient thermal insulation uses both in inert and oxidative atmosphere. [ABSTRACT FROM AUTHOR]

SiO 2 -doped Sb material is proved to be a promising candidate for phase change memory (PCM) use because of its high crystallization temperature (∼239 °C), large crystallization activation energy (4.05 eV), and good data retention ability (162 °C for 10 years). The band gap is broadened and the grain size is refined by SiO 2 doping. The reversible resistance transition can be achieved by an electric pulse as short as 5 ns for the PCM cell based on SiO 2 -doped Sb material. A lower operation power consumption (the energy for RESET operation 1.1 × 10 −11 J) is obtained. In addition, SiO 2 -doped Sb material shows a good endurance of 2.5 × 10 5 cycles. [ABSTRACT FROM AUTHOR]

Hypothesis The surface chemistry of synthetic amorphous silicas is essential for their applicational performance and for understanding their interactions with biological matter. Synthesis of silica by flame spray pyrolysis (FSP) allows to control the content and type of hydroxyl groups which also affects the cytolytic activity. Experiments By controlling the FSP process variables, silica nanoparticles with the same specific surface area but different surface chemistry and content of internal silanols are prepared by combustion of hexamethyldisiloxane sprays, as characterized by Raman and infrared spectroscopy, thermogravimetric analysis, and titration with lithium alanate. Cytolytic activity is assessed in terms of membrane damage in human blood monocytes in vitro . Findings Unlike commercial fumed silica, FSP-made silicas contain a significant amount of internal silanol groups and a high surface hydroxyl density, up to ∼8 OH/nm 2 , similar to silicas made by wet-chemistry. Increasing the residence time of particles at high temperature during their synthesis reduces the internal and surface hydroxyl content and increases the relative amount of isolated silanols. This suggests incomplete oxidation of the silica matrix especially in short and “cold” flames and indicates that the silica particle formation pathway involves Si(OH) 4 . The surface chemistry differences translate into lower cytolytic activity for “cold-” than “hot-flame” silicas. [ABSTRACT FROM AUTHOR]

In this work, we demonstrate a self-assisted VLS growth of GaAs nanowires directly on GaAs (111)B substrates without assistance of SiO 2 layer. We believe that with this technique, we can overcome some inherent problems that usually occur in conventional self-assisted VLS growth and simplify the process. Moreover, to study the effect of substrate temperature, each nanowire sample was fabricated at the different temperature from 400 °C to 600 °C using Molecular Beam Epitaxy (MBE) technique. Surface morphology, elemental composition, and crystal structure of nanowire samples were characterized by Scanning Electron Microscope (SEM), Energy-dispersive X-ray spectroscopy (EDX), and X-ray Diffraction Analysis (XRD) respectively. [ABSTRACT FROM AUTHOR]

Exposure to crystalline silica particles causes silicosis, an occupational disease leading to an overproduction of collagen in the lung. The first step of this pathology is characterized by the release of inflammatory mediators. Tumour necrosis factor (TNF) is a pro-inflammatory cytokine directly involved in silica-induced pulmonary fibrosis. The marine demosponge Chondrosia reniformis is able to incorporate silica grains and partially dissolve the crystalline forms apparently without toxic effects. In the present work, C. reniformis tissue explants were treated with fine quartz dust and the expression level of fibrogenic genes was assayed by qPCR, demonstrating an overexpression of a fibrillar and a non-fibrillar collagen and of prolyl-4-hydroxylase enzyme. The deposition of new collagen could also be documented in quartztreated sponge explants. Furthermore, TNF pro-inflammatory cytokine overexpression and involvement in silica-induced sponge collagen biosynthesis was demonstrated in quartz-treated explants as compared with controls by means of specific TNF inhibitors affecting the fibrogenic gene response. As no documentable detrimental effect was observed in treated explants, we conclude that the C. reniformis unique quartz engulfment and erosion is physiological and beneficial to the animal, leading to new collagen synthesis and strengthening of the body stiffness. Thus, we put forward the hypothesis that an ancient physiological behaviour from the lowest of the Metazoa, persisting through evolution via the samemolecularmediators such as TNF, may have become the cause of disease in the specialized tissues of higher animals such as mammals. [ABSTRACT FROM AUTHOR]

Novel mesoporous silica supported ILs have been prepared and successfully applied as a heterogeneous catalyst in Mannich reactions. The excellent recyclability of the supported catalyst, mild reaction conditions, good to excellent yields, low catalyst loading, and operational simplicity are the important features of this methodology. [ABSTRACT FROM AUTHOR]

A composite mineral admixture was prepared by grinding a mixture of steel slag and silica fume (steel slag/silica fume ratio is 92:8 or 84:16, by mass). A layer of silica fume was uniformly adsorbed on the steel slag particles. The influence of this steel slag-silica fume composite mineral admixture on the hydration of a cement-based composite binder and the properties of its concrete were investigated. The results show that the silica fume in the composite mineral admixture contributes significantly to the consumption of Ca(OH) 2 and enhances the connection between the steel slag particles with the surrounding C-S-H gel. The activity of the composite mineral admixture improves with an increase in the silica fume content. The retarding effect of the composite mineral admixture on the early hydration of cement is significant. However, a proper cement replacement by the composite mineral admixture can improve the late-age pore structure of hardened paste as well as the strength, chloride ion resistance, carbonation resistance, and sulfate attack resistance of concrete. The proper addition of the composite mineral admixture can reduce the drying shrinkage of concrete. [ABSTRACT FROM AUTHOR]

Nanofluids (NFs), wherein solid nanoparticles (NPs) are dispersed in traditional heat exchange fluids, are recognized for improving the performance of traditional fluids by enhancing their thermal conductivity (TC). The presence of impurities or undesired phases in commercial NPs may influence the thermo-physical properties of NFs including TC and viscosity, which makes it difficult to understand the real effect of NPs on heat transport characteristics of NFs. Moreover, the presence of these impurities in commercial NPs is unavoidable and their removal from commercial NPs with no negative impact on composition of NPs is challenging. To study the impact of impurities on thermo-physical properties of NFs a systematic experimental work was performed using commercial α-SiC and SiO 2 NPs as the secondary phase as it commonly co-exists in commercial SiC batches. For this purpose, a series of NFs containing 9 wt% of α-SiC/SiO 2 NP mixture with different content of SiO 2 NPs from 5 to 50% were fabricated and investigated. The results show that as the undesired impurity phase (SiO 2 ) increases, TC of NFs decreases slightly while viscosity increases dramatically. This may be a sound path to tuning the viscosity of the NFs while the achieved high TC is mildly influenced by the secondary phase. [ABSTRACT FROM AUTHOR]

Objectives The aim of this study was to assess the effect modification of the association between tobacco smoking and phenotypes of lung cancer (histological type, tumor location, and age at diagnosis) by occupational exposure to asbestos or to crystalline silica. Materials and methods The CaProMat study is a pooled case-only study including 7256 male lung cancer cases recruited between 1996 and 2011 in France and Canada. Two job-exposure matrices (JEMs) were used to assess occupational exposure to asbestos and crystalline silica. Statistical interactions between tobacco smoking and occupational exposure to asbestos or crystalline silica were assessed using unconditional logistic regression models for histological type and tumor location and linear regression models for age at diagnosis. Results Tobacco smoking was associated with squamous cell carcinoma and small cell carcinomas as well as an earlier age at diagnosis. Additional exposure to either asbestos or crystalline silica did not modify the effect of tobacco smoking for either histological type or age at diagnosis. Neither tobacco smoking nor occupational exposure to asbestos or crystalline silica influenced tumor location. Conclusions Tobacco smoking was the main factor related to histological type and age at diagnosis. Those associations were not modified by occupational exposure to asbestos or crystalline silica. [ABSTRACT FROM AUTHOR]

Background: Inhalation of crystalline silica is associated with pulmonary inflammation and silicosis. Although silicosis remains a prevalent health problem throughout the world, effective treatment choices are limited. Imipramine (IMP) is a FDA approved tricyclic antidepressant drug with lysosomotropic characteristics. The aim of this study was to evaluate the potential for IMP to reduce silicosis and block phagolysosome membrane permeabilization. Methods: C57BL/6 alveolar macrophages (AM) exposed to crystalline silica ± IMP in vitro were assessed for IL-1β release, cytotoxicity, particle uptake, lysosomal stability, and acid sphingomyelinase activity. Short term (24 h) in vivo studies in mice instilled with silica (± IMP) evaluated inflammation and cytokine release, in addition to cytokine release from ex vivo cultured AM. Long term (six to ten weeks) in vivo studies in mice instilled with silica (± IMP) evaluated histopathology, lung damage, and hydroxyproline content as an indicator of collagen accumulation. Results: IMP significantly attenuated silica-induced cytotoxicity and release of mature IL-1β from AM in vitro. IMP treatment in vivo reduced silica-induced inflammation in a short-term model. Furthermore, IMP was effective in blocking silica-induced lung damage and collagen deposition in a long-term model. The mechanism by which IMP reduces inflammation was explored by assessing cellular processes such as particle uptake and acid sphingomyelinase activity. Conclusions: Taken together, IMP was anti-inflammatory against silica exposure in vitro and in vivo. The results were consistent with IMP blocking silica-induced phagolysosomal lysis, thereby preventing cell death and IL-1β release. Thus, IMP could be therapeutic for silica-induced inflammation and subsequent disease progression as well as other diseases involving phagolysosomal lysis. [ABSTRACT FROM AUTHOR]

In this work, a fluoride-modified Phillips catalyst was investigated by using combined experimental and computational methods. The addition of fluoride to the Phillips Cr/SiO2 catalyst can increase the activity of the catalyst calcined at a low temperature and the molecular weight of the polyethylene product. DFT calculations were performed to show that the difference of the Gibbs free energy barriers between chain transfer and chain propagation increased after the introduction of the fluoride onto the silica surface, which is in accordance with the increased molecular weight of the polyethylene produced by the fluoride-modified Phillips Cr/F-SiO2 catalyst. The computational results also reflect the increase of the activity of the ethylene/1-hexene copolymerization after the introduction of fluoride, although the modification has little effect on the regioselectivity of the produced ethylene/1-hexene copolymer. Moreover, copolymers produced by the fluoride-modified Phillips catalyst with more short-chain branches (SCBs) in the high-molecular-weight fraction and a significant enhancement of the environmental stress crack resistance can be explained from the results of the DFT calculations. [ABSTRACT FROM AUTHOR]

The role of sodium fluoride, added to quartz before the latter is mechanically activated, in the solid-phase conversion of depleted uranium tetrafluoride into uranium oxides without mixing of the components of the mixture is determined. [ABSTRACT FROM AUTHOR]

In this study, (jute fiber)/polyethylene biocomposites were prepared by using a hot press machine. Jute fiber was investigated as a reinforcing filler material for producing structural composites with better environmental performance. The effects of clay and silica addition on the physical, mechanical, and thermal properties of (jute fiber)-reinforced polyethylene biocomposites with different fiber loadings (5, 10, 15, and 20 wt%) were investigated. The biocomposites were characterized by Fourier-transform infrared spectroscopy, scanning electron microscopy, and thermogravimetric analysis. The composite surface area and pore volume were determined by using the Brunauer-Emmett-Teller equation. The mechanical properties were investigated by using a Universal Testing Machine. Because of Si-O-Si stretching vibration, the O-H group from 3,200 to 3,400 cm−1 disappeared. The scanning electron microscopy results proved that a significant difference among the composites was present due to the interfacial bonding between the fiber and the matrix. J. VINYL ADDIT. TECHNOL., 23:E107-E112, 2017. © 2015 Society of Plastics Engineers [ABSTRACT FROM AUTHOR]

Ion exchange is a widely used technique for the recovery of gallium from Bayer liquor of the alumina industry. However, development of cheap, selective, reusable and environmentally friendly resin materials is essential. Novel resins must be resistant to both the highly alkaline environment of Bayer liquor and the acidic media used for stripping. In this study, chitosan was combined with silica. The hybrid chitosan-silica (CS) adsorbent matrix was chemically immobilized with the organic ligands 8-hydroxyquinoline (8-HQO) and 8-hydroxyquinaldine (8-HQA), the latter being the C2-methylated analogue of the former. Adsorption of Ga(III) and Al(III) by CS functionalized with 8-HQO and 8-HQA was studied as a function of kinetics, equilibrium concentration, aqueous pH and temperature, to determine the conditions to get the highest selectivity for Ga(III). With the 8-HQA-functionalized adsorbent, selective stripping of the loaded metal ions by sulfuric acid resulted in a better Ga(III)/Al(III) separation, in comparison with 8-HQO-CS. In contrast to the resins that are currently in use, no significant loss in Ga(III) loading was observed after seven consecutive alkaline adsorption and acidic desorption cycles. It was also possible to separate Ga(III) from a synthetic Bayer solution using an ion-exchange column with 8-HQA-functionalized CS as the stationary phase. The studied adsorbents are considered promising resin materials to make gallium recovery from Bayer liquor of lower environmental impact and less expensive by significantly decreasing the resin cost. [ABSTRACT FROM AUTHOR]

Activation of low calcium fly ash is investigated using activating solutions of sodium hydroxide (NaOH) and sodium silicate (Na 2 SiO 3 ). The oxide ratio of Na 2 O relative to the total reactive silica in the activated mix provides consistent results in achieving the highest ultimate strength. The total reactive silica used for calculating the ratio consists of the reactive silica contributed by fly ash and the silica from the activating solution. There is an increase in the ultimate compressive strength on increasing the total sodium content relative to the total reactive silica content in the activated system. Increasing the sodium content beyond a certain limit does not provide additional gain in the ultimate compressive strength. The ratio of total reactive SiO 2 to Na 2 O in the activated system equal to 4.72 is shown to provide the highest compressive strength and there is no further increase in the ultimate strength on increasing the sodium content. A N-A-S-H type gel with reaction products containing Si, Al and Na, is formed in the activated system. The ultimate strength achieved is directly related to the reaction product content in the system and is dependent on the extent of glassy phase dissolution from fly ash. The extent of glassy phase dissolution and the quantity of reaction product formed in the system increases with an increase in the molarity of NaOH, which also contributes to an increase in the sodium content in the activating solution. The decrease in the unreacted glassy phase content of fly ash is sensitive to temperature at a lower molarity of NaOH. The Al/Na ratio in the reaction product approaches a value of 0.9 on increasing the sodium content in the activated system. The Si/Al ratio in the reaction product varies within a range of 2.3–2.8. [ABSTRACT FROM AUTHOR]

Objective We investigated the role of endoplasmic reticulum stress (ERS) in silica-induced apoptosis in alveolar macrophages in vitro . Methods RAW264.7 cells were incubated with 200 μg/mL silica for different time periods. Cell viability was assayed by the MTT assay. Cell apoptosis was evaluated by DAPI staining, flow cytometry analysis, and Western blot analysis of caspase-3. Morphological changes in the endoplasmic reticulum were observed by transmission electron microscopy. The expression of ERS markers binding protein (BiP) and CCAAT-enhancer-binding protein homologous protein (CHOP) was examined by Western blotting and real-time PCR. As an inhibitor of ERS, 4-phenylbutyric acid (4-PBA) was used in the experiments. Results Silica exposure induced nuclear condensation and caspase-3 expression in RAW264.7 cells. The number of apoptotic cells increased after silica exposure in a time-dependent manner. Silica treatment induced expansion of the endoplasmic reticulum. In addition, the expression of BiP and CHOP increased in silica-stimulated cells. Furthermore, 4-PBA treatment inhibited silica-induced endoplasmic reticulum expansion and the expression of BiP and CHOP. Moreover, 4-PBA treatment attenuated nuclear condensation, reduced apoptotic cells, and downregulated caspase-3 expression in silica-stimulated cells. Conclusion Silica-induced ERS is involved in the apoptosis of alveolar macrophages. [ABSTRACT FROM AUTHOR]

In the last decades, silica particles of a variety of sizes and shapes have been characterized and chemically modified for several applications, from chromatographic separation to dental supplies. The present study proposes the use of aminopropyl triethoxysilane (APTS) silanized silica particles to immobilize the proteolytic enzyme trypsin for the development of a bioreactor. The major advantage of the process is that it enables the polypeptides hydrolysis interruption simply by removing the silica particles from the reaction bottle. Silanized silica surfaces showed significant morphological changes at micro- and nanoscale level. Chemical characterization showed changes in elemental composition, chemical environment, and thermal degradation. Their application as supports for trypsin immobilization showed high immobilization efficiency at reduced immobilization times, combined with more acidic conditions. Indirect immobilization quantification by reversed-phase ultrafast high performance liquid chromatography proved to be a suitable approach due to its high linearity and sensitivity. Immobilized trypsin activities on nonmodified and silanized silica showed promising features (e.g., selective hydrolysis) for applications in proteins/peptides primary structure elucidation for proteomics. Silanized silica system produced some preferential targeting peptides, probably due to the hydrophobicity of the nanoenvironment conditioned by silanization. [ABSTRACT FROM AUTHOR]

Ni catalysts supported on MgO SiO 2 were assessed in the steam reforming reaction of glycerol for the study of the H 2 production and carbon deposition with different MgO contents as additives. The catalysts were prepared with commercial SiO 2 by the aqueous impregnation method and characterized by energy dispersive X-ray spectroscopy, specific surface area, X-ray diffraction, thermogravimetric analysis, X-ray diffraction in situ with O 2 , temperature programmed reduction with H 2 , X-ray diffraction in situ with H 2 , temperature programmed desorption with H 2 and scanning electron microscopy. The glycerol steam reforming reaction took place at 600 °C for 5 h, with a water/glycerol molar ratio of 12/1 at 5 mLh −1 . N 2 was used as the carrier gas. The characterization of the samples showed the interaction of Ni with the support increases with the MgO addition, due to the formation of a Ni Mg silicate hydrate and MgNiO 2 solid solution; as a result, both metallic area and dispersion also increased. Catalytic results showed similar gaseous products yields (H 2 , CH 4 , CO and CO 2 ) for mixed-matrix catalysts, however, a lower carbon deposition on 10 wt%Ni catalyst supported on 30 wt%MgO SiO 2 was observed. [ABSTRACT FROM AUTHOR]

Silica is the second most common element after oxygen, and therefore, exposures to crystalline silica dust occur in a large variety of occupations such as metal foundries, constructions, and ceramic, quarry, and pottery industries. Since crystalline silica exposure has been linked with silicosis, lung cancer, and other pulmonary diseases, adverse effect attributed to this element has be a cause for concern worldwide. Silica dust exposure in workers is still considered to be important health problem especially in developing countries. The aim of the study was to investigate the effects of occupational silica exposure on oxidative stress parameters including the activities of superoxide dismutase (SOD), catalase (CAT), glutathione reductase (GR), glutathione peroxidase (GPx), and levels of total glutathione (GSH) and thiobarbituric acid reactive substance (TBARS) as well as immune system parameters such as interleukin (IL)-1α, IL-1β, IL-2, IL-4, IL-6, and IL-10 and tumor necrosis factor (TNF)-α in Turkish ceramic workers. In this study, nearly 50% of Turkish ceramic workers were diagnosed with silicosis. Eighty-four percent of these silicotic workers were found to present with profusion category 1 silicosis, whereas controls (n= 81) all displayed normal chest radiographs. Data demonstrated a significant decrease in levels of GSH and activities of CAT, SOD, and GPx, but a significant increase in MDA levels and activity of GR in all workers. Further, workers possessed significantly higher levels of IL-1α, IL-1β, IL-2, IL-4, IL-6, IL-10, and TNF-α. These observations suggest that ceramic workers may have impaired antioxidant/oxidant status and activated immune system indicative of inflammatory responses. [ABSTRACT FROM PUBLISHER]

The first experiment on electronuclear reaction initated by axially channeled 700 MeV electrons in a Si crystal [1] revealed remarkable depth oscillations of reaction yield. The effect was satisfactory explained [2] by computer simulations using binary collisions model. In this work the oscillations effect is investigated for planar channeled electrons in a Si crystal using the new computer code BCM-1.0 which allows both classical and quantum calculations of channeled electrons flux density. [ABSTRACT FROM AUTHOR]

Silica and iron are major constituents in ambient particulate matter, and iron is a common impurity in many engineered nanomaterials. The purpose of this work was to determine the pro-inflammatory and other biological effects and mechanism of particle size and iron presence under low dose, non-cytotoxic conditions that are likely to approximate actual exposure levels, in contrast with higher dose studies in which cytotoxicity occurs. Specifically, human-derived THP-1 macrophages were exposed to 1 μg/ml of pristine and iron-coated 50 nm and 2 μm engineered silica nanoparticles. Particles were first characterized for size, size distribution, surface area, iron concentration, phase and aggregation in cell culture media. Then, biological assays were conducted to determine a non-lethal dose used in subsequent experiments. Superoxide production, lipid peroxidation, and increased pro-inflammatory cytokine (TNF-α and IL-1β) mRNA expression were measured as a function of particle size and iron presence. Smaller particle size and the presence of iron increased superoxide production, lipid peroxidation, and the induction of pro-inflammatory cytokine mRNA expression. Separate addition of an iron-chelator, a scavenger of superoxide and hydrogen peroxide, and an inhibitor of phosphatidylcholine specific phospholipase C (PC-PLC), suppressed the increase in cytokine mRNA expression. Furthermore, free iron itself showed none of the aforementioned effects. The results highlight the importance of particle size and iron in lung inflammation for both natural and engineered nanomaterials, under low dose, non-toxic conditions, and support the role of an oxidant, lipid peroxidation and PC-PLC dependent inflammatory mechanism. [ABSTRACT FROM AUTHOR]

We report results of measurements of Nb stripline resonators with linewidths ranging from 1.0 to 0.25 μ m, fabricated using an 8-Nb-layer process with planarized SiO2 dielectric developed at MIT Lincoln Laboratory for superconductor single-flux-quantum circuits. The fundamental resonant frequency f 0 was varied from 2.3 to 4.5 GHz. The results show that, at 4 K, the losses for the narrowest lines are dominated by losses in the dielectric. At high power, the nonlinear niobium losses dominate. Spiral inductors have also been used to design and fabricate multipole low-pass filters with three and five poles with cutoff at 1 GHz. The measured and simulated results for the filters agree very well and show almost ideal properties. The precision and high reproducibility of this fabrication process hold the promise of fabricating multipole filters without the need for tuning the individual poles. [ABSTRACT FROM PUBLISHER]

The health effects of silica may depend on the inherent properties of crystalline silica or on external factors affecting the biological activity or distribution of its polymorphs. Inhaled crystalline silica is classified as a Group I carcinogen, however, information on the health effects of amorphous silica is still insufficient. Considering that alveolar macrophages play a key role in both innate and adaptive immune responses for removal of foreign bodies that enter via the respiratory system, we treated sheet-like glass particles (SGPs), a type of noncrystalline amorphous silica, to MH-S cells, an alveolar macrophage cell line. SGPs reduced the generation of ROS and NO and induced cell death via multiple pathways. Although the expression of CD80, CD86, and CD40, increased by exposure to SGPs, the expression of MHC class II molecules had not notably changed. Additionally, expression of ICAM-1 tended to decrease. In mice, SGPs were distributed in the interstitial region of the lung without notable pathological lesion on day 14 after a single intratracheal instillation. Pulmonary total cell number increased significantly with the highest dose, but the levels of all measured inflammatory cytokines and chemokines, except IL-1, were lower in BAL fluid from SGP-treated mice compared to control. More interestingly, the expression of antigen presentation-related proteins was enhanced in the lungs of SGP-exposed mice concomitant with an increase in the number of mature dendritic cells, whereas the expression of ICAM-1, an important adhesion molecule for helper T cell recruitment, was suppressed. Taken together, we suggest that SGPs may induce adverse health effects by down-regulating function of immune cells in the lungs. Furthermore, ICAM-1 may play a key role in immune response to remove pulmonary SGPs. [ABSTRACT FROM AUTHOR]

Fluorescence intensity is vital for fluorescence sensing and imaging because it determines the sensing sensitivity and imaging brightness. This study reports plasmon-enhanced fluorescence by engineering plasmonic nanostructures, that are SiO-coated Au nanoshell dimers with a high yield exceeding 60 %. With this elaborately designed nanostructure, we show that the thin SiO shell can conveniently distance the fluorophore from the underneath metal, thereby effectively avoiding fluorescence quenching. Meanwhile, the inner Au nanoshell dimers create abundant hot spots at particle-particle junctions and enable near-infrared fluorescence enhancement. The largest fluorescence enhancement achieved is 69 times for the design with a 9 nm external SiO shell, as is also confirmed by three-dimensional finite-difference time-domain simulations. This dramatically increased fluorescence has great significance in fluorescence-based sensing and imaging. [ABSTRACT FROM AUTHOR]

The effect of a simple visible halogen lamp was studied in the Fenton-type oxidation of three model aqueous pollutants differing in their structure and electrostatic charge, methylorange (MO), methylene blue (MB) and paranitrophenol (PNP), using maghemite nanoparticles (γ-Fe 2 O 3 NP), or maghemite/silica nanocomposite microspheres (γ-Fe 2 O 3 /SiO 2 MS) as heterogeneous catalysts. These materials, which were fully characterized, differ in size, morphology, porosity and microstructure, although their catalytic activity is related to the same γ-Fe 2 O 3 nanoparticles. Both have a strong magnetic susceptibility, but only the MS catalyst can be easily recovered by magnetic settlement. Whatever the catalyst, the pollutant tested, or the experimental conditions used, much better decolorization rates and mineralization efficiencies were recorded under illumination by visible light in comparison to the same tests in the dark. The large range of experimental conditions tested enabled us to propose a mechanism for photocatalytic activity. Experiments of long-term stability showed that the MS catalyst, although generally less active than the NP catalyst, retained almost all of its activity after five repeated experiments under visible light. The good stability of this catalyst was also confirmed by the low level of iron leaching, making it suitable candidate for an application as photo-Fenton catalyst in industrial wastewater treatment. [ABSTRACT FROM AUTHOR]

The purpose of this study was to investigate the anti-fibrotic effect and possible mechanism of bone marrow mesenchymal stem cells (BMSCs) in silica-induced lung injury and fibrosis in vivo and in vitro. In vivo, rats were exposed to 50 mg/ml silica intratracheally. The rats were sacrificed on day 15 or day 30 after intravenous injection of BMSCs. Histopathological examination demonstrated that BMSCs decreased the blue areas of collagen fibers and the number of nodules. Alveolar epithelium was damaged by silica, but it was restored by BMSCs. In vitro, BMSCs co-cultured with RLE-6TN cells in 6-Transwell plates were evaluated to determine the possible mechanism. The results demonstrated that BMSCs downregulated the expression of collagen I and III. BMSCs reversed morphological abnormalities and reduced the proliferation of RLE-6TN cells. These data showed that BMSCs did not give rise to alveolar epithelial cells directly, while the levels of hepatocyte growth factor, keratinocyte growth factor and bone morphogenetic protein −7 increased and expression of tumor necrosis factor-α and transforming growth factor-β1 decreased in the 6TN + Silica + BMSCs group compared with the 6TN + Silica group. Our results revealed that BMSCs exerted anti-fibrotic effects on silica-induced pulmonary fibrosis, which might be associated with paracrine mechanisms rather than differentiation. [ABSTRACT FROM AUTHOR]

This study described the preparation of silica-coated Au nanorods (AuNR/SiO 2 ) in a colloidal solution, assessed their property of photothermal conversion, and investigated their ability to kill cancer cells using photothermal conversion. Au-seed nanoparticles were produced by reducing hydrogen tetrachloroaurate (HAuCl 4 ) with sodium borohydride (NaBH 4 ) in aqueous n-hexadecyltrimethylammonium bromide (CTAB) solution. AuNRs were then fabricated by reducing HAuCl 4 and silver nitrate (AgNO 3 ) with l -ascorbic acid in the aqueous CTAB solution in the presence of Au-seed nanoparticles. The as-prepared AuNRs were washed by a process composed mainly of centrifugation to remove the CTAB. The washed AuNRs were coated with silica by mixing the AuNR colloidal solution, an aqueous solution of (3-aminopropyl)trimethoxysilane, and tetraethylorthosilicate/ethanol solution with a water/ethanol solution. We found that the addition of AuNR/SiO 2 in water, in mice, and in a culture medium with cancer cells, followed by irradiation with a laser, cause an increase in temperature, demonstrating that AuNR/SiO 2 have the ability of photothermal conversion. In addition, the cancer cells in the culture medium were found to be killed due to the increase in temperature caused by the photothermal conversion. [ABSTRACT FROM AUTHOR]

Seawater contains a number of organic and inorganic components that cause fouling of membranes when subjected to a process of reverse osmosis desalination. This fouling is one of the most important problems in the management of desalination plants, as it entails a significant loss in system performance. For membranes to be able to continue operating under appropriate conditions, they must undergo periodic cleaning protocols. This paper presents the results obtained when, subjecting a previously fouled aromatic polyamide membrane to different washing agents and using different concentrations of the same. Optimal concentrations of cleaning reagents were established. The results indicate that the performance of cleaning using a mixture of reagents, and alternating alkaline and acidic media, enabled maximum recovery of the membrane permeate flux (94.2 %) and a significant reduction in the consumption of cleaning reagents. [ABSTRACT FROM AUTHOR]

Background Brazil is an exporter of precious stones and craftsmen often work in poor conditions. We assessed silica-related diseases among crystal craftsmen and the complexity of its control. Methods Case-series including 118 subjects evaluated from 2006 to 2015, based on medical interviews, chest X-rays, spirometry, and respirable silica samples. Results Median age and length of exposure were 32 and 13 years, respectively. Silicosis, with 1/0 as a threshold, was diagnosed radiologically in 57 individuals (48.3%). Respirable silica concentrations were 0.9-29.3 times greater than the Brazilian occupational exposure limit. A Receiver Operating Characteristic (ROC) curve with the same diagnosis threshold showed best discrimination at a cut point of 12.5 years of exposure, corresponding to 4.85 mg-y/m3 of cumulative silica exposure. There was a significant decline in FEV1 across radiological and cumulative silica exposure categories. Eleven individuals (9.3%) had mycobacterial diseases at baseline or follow-up. Conclusion Crystal craftsmen continue to suffer from silicosis, lung function impairment, comorbidity, and death due to silicosis. To date collective protection in some work sheds has not diminished silica levels. Long-term follow-up is needed to evaluate further improvements in preventive measures. Am. J. Ind. Med. 60:239-247, 2017. © 2017 Wiley Periodicals, Inc. [ABSTRACT FROM AUTHOR]

Shear thickening is a general process crucial for many processed products ranging from food and personal care to pharmaceuticals. Theoretical calculations and mathematical simulations of hydrodynamic interactions and granular-like contacts have proved that contact forces between suspended particles dominate the rheological characteristic of colloidal suspensions. However, relevant experimental studies are very rare. This study was conducted to reveal the influence of nanoparticle (NP) interactions on the rheological behavior of shear-thickening fluids (STFs) by changing the colloidal surface chemistries. Silica NPs with various surface chemical compositions are fabricated and used to prepare dense suspensions. Rheological experiments are conducted to determine the influence of NP interactions on corresponding dense suspension systems. The results suggest that the surface chemistries of silica NPs determine the rheological behavior of dense suspensions, including shear-thickening behavior, onset stress, critical volume fraction, and jamming volume fraction. This study provides useful reference for designing effective STFs and regulating their characteristics. [ABSTRACT FROM AUTHOR]

This study focused on the interfacial combination of silica and lignin-polysaccharides during lignocellulose fractionation of rice straw using scanning electric microscopy (SEM), x-ray photoelectron spectroscopy (XPS), and x-ray diffraction (XRD) techniques. Silica was deposited on the exterior surface of rice straw in the form of Si(OR)x, Si O Si, SiOx, and Si C respectively, while not in the form of elemental Si. After delignification and alkalization, silica was deposited on the surface of polysaccharide with a more regular pattern. It is due to that silica reacted with polysaccharide to form SiOx and Si(OR)x during the decomposition of lignin and hemicellulose, leading to the remained framework structure of crystalline cellulose. After the decomposition of polysaccharide, silica was embedded into lignin fragments, and shown as an amorphous opal. For silica-lignin, Si O Si was gradually transferred to Si(OR)x instead of Si C. The capacities of the fractionated components to bind or store silica were in order of lignin > polysaccharides > lipids. Moreover, the fractionated components of rice straw were associated with the different ultrastructural forms of the silica. [ABSTRACT FROM AUTHOR]

Background: This study aimed to investigate the pulmonary functions of silicaexposed workers and their health-related quality of life in an insulator manufacturing industry. Materials and Methods: In this cross-sectional study, participants selected from the manufacturing unit (n = 127) constituted the exposed group and those from the administrative department (n = 30) constituted the unexposed group. All subjects were evaluated using personal air sampling of crystalline silica, pulmonary function tests, and a quality of life questionnaire (36-item short form health survey [SF-36]). Results: The mean (SD) concentrations of crystalline silica were 0.507 (0.23) mg/m3 and 0.0116 (0.008) mg/m3 for the exposed and unexposed groups, respectively. All the pulmonary function indices and all the physical and mental health domains of the workers were significantly lower than those of the administrative clerks (p < 0.05). The silica concentration did not significantly correlate with the quality of life components and all the pulmonary function indices (p > 0.05), except for forced vital capacity (FVC) and forced expiratory volume in one second (FEV1) (p < 0.05). Conclusion: In conclusion, the workers exposed to higher levels of crystalline silica had lower values of pulmonary function indices and lower health-related quality of life; however, further follow-up studies are needed to confirm these findings. [ABSTRACT FROM AUTHOR]

A particle generation apparatus and methodology is described for its application to prepare heterogeneous particles of defined chemical composition and their subsequent delivery to human lung cell cultures. A concentric type nebulizer was used together with a single pass spray chamber that was operated at two different temperature settings, either room temperature or to produce intact particles, at nonuniform temperature with the central axis measuring 54°C. Silica (SiO2) particles in the micrometer size range were produced from the aggregation of nanoparticles. Tumor necrosis factor (TNF)-α, a well-characterized cytokine, was incorporated as a secondary soluble component within host silica particles for application as a proof-of-concept heterogeneous particle type. The overall particle deposition and wetting efficiency into media was 2.0 ± 0.4%, and the average size of particles that impacted and sank in the growth medium was 3.4 µm. The particle dose, reported as particle-to-cell ratio, spanned 0.1 to ∼2.5. Co-cultures of A549 and differentiated human monocytic cells (THP-1*) exposed to silica particles caused IL-6 upregulation, but not IL-8. For the silica plus TNF-α particle type, ICAM-1 signal increased in A549 mono-cultures as the particle-to-cell ratio increased, yet an estimated 90% of the TNF-α was denatured or possibly bound to the silica particle host, and was therefore bio-unavailable. Method quantitation using particles having two different chemical compositions has been described, illustrating capability for subsequent systematic investigation of the role of particles having different chemical composition in the human health aspects of the particulate air pollution issue. Copyright © 2016 American Association for Aerosol Research [ABSTRACT FROM PUBLISHER]