In this proof-of-concept study, an agricultural biocide (imidacloprid) was effectively loaded into the mesoporous silica nanoparticles (MSNs) with different pore sizes, morphologies and mesoporous structures for termite control. This resulted in nanoparticles with a large surface area, tunable pore diameter and small particle size, which are ideal carriers for adsorption and controlled release of imidacloprid. The effect of pore size, surface area and mesoporous structure on uptake and release of imidacloprid was systematically studied. It was found that the adsorption amount and release profile of imidacloprid were dependent on the type of mesoporous structure and surface area of particles. Specifically, MCM-48 type mesoporous silica nanoparticles with a three dimensional (3D) open network structure and high surface area displayed the highest adsorption capacity compared to other types of silica nanoparticles. Release of imidacloprid from these nanoparticles was found to be controlled over 48 ...
OBJECTIVE: To determine early signs of renal injury due to occupational silica exposure. DESIGN: Cross-sectional analytical research. SETTINGS: Kenyatta National Hospital for the referent population and Clayworks ceramics, bricks and tiles factory for the assessment of occupational silica exposure. SUBJECTS: Thirty three non-smoking silica-exposed male industrial workers and 38 non-smoking male referents participated in this study. RESULTS: Silica-exposed males excreted significantly increased levels of U.TP, U.Malb, U.ALP, U.y-GT and U.LDH compared to referent males. Among the silica-exposed males, U.Si negatively correlated significantly with age, U.TP correlated significantly to each of U.ALP and U.LDH. However, no correlation was observed between work duration and U.Si. CONCLUSION: The present study shows that there is associated glomerular and proximal tubular damage among silica exposed workers which is not duration related and is seemingly subclinical and nonprogressive and urinary silica ...
TY - JOUR. T1 - A novel adsorbent photocatalyst consisting of titania and mesoporous silica nanoparticles. AU - Uchiyama, Hiroaki. AU - Suzuki, Keisei. AU - Oaki, Yuya. AU - Imai, Hiroaki. PY - 2005/11/25. Y1 - 2005/11/25. N2 - The nanoscale combination of crystalline titania and mesoporous silica particles was successfully applied as a photocatalytic adsorbent for the rapid removal from air and complete decomposition of organic molecules. The composites consisted of anatase particles ca. 7 nm in diameter and mesoporous silica particles 10-100 nm in diameter, which provided a specific surface area of more than 1000 m2/g. The composites were prepared through the assembly of surfactant micelles and siliceous species in the presence of the titania nanoparticles. Acetaldehyde was quickly removed from air due to the large surface area of the mesoporous silica and then was gradually decomposed into carbon dioxide under UV illumination with mass transfer between the adsorbent and the titania ...
TY - JOUR. T1 - Bisindole anchored mesoporous silica nanoparticles for cyanide sensing in aqueous media. AU - Kim, Hyun Jung. AU - Lee, Hyejin. AU - Lee, Ji Ha. AU - Choi, Dong Hoon. AU - Jung, Jong Hwa. AU - Kim, Jong Seung. PY - 2011/10/21. Y1 - 2011/10/21. N2 - For CN- recognition, a series of bisindolyl compounds 1-3 were prepared, and their chromodosimetric color changes toward anions were investigated. Nucleophilic addition of the cyanide ion to the meso position of the bisindolyl group gave rise to breaking of the double bond conjugation, thereby inducing spectroscopic changes in the compound. Mesoporous silica nanoparticles 3 also gave color changes from deep orange to yellow in response to the cyanide ion.. AB - For CN- recognition, a series of bisindolyl compounds 1-3 were prepared, and their chromodosimetric color changes toward anions were investigated. Nucleophilic addition of the cyanide ion to the meso position of the bisindolyl group gave rise to breaking of the double bond ...
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With years of experience in the pharmaceutical and life science sector, Creative Diagnostics recently launches a wide range of fluorescent silica particles with a high amount of covalently bound fluorescence dye in the silica matrix. These new fluorescent silica nanoparticles are available with red fluores...
Page contains details about hybrid triethoxysilylated ligand-modified fluorescent silica nanoparticles . It has composition images, properties, Characterization methods, synthesis, applications and reference articles : nano.nature.com
Flavonoids such as quercetin and its derivatives, which are normally isolated from plants, are antioxidants with medicinal and therapeutic applications for the treatment of cancer, cardiovascular disease and other conditions because they act against tumors, inflammation, and reactive oxygen species. At the same time, because they are photoactive compounds, flavonoids are highly susceptible to degradation and activity loss after extraction from biological sources. Therefore, methods are needed to retain the activity of flavonoids during physicochemical processes and storage. A possible material of interest for binding, protection and release of a wide variety of compounds are engineered silica particles. Porous silica nanoparticles are of interest for the recovery, and more recently, the delivery of therapeutics. Recent progress in metal oxide chemistry allows the synthesis of silica nanoparticles of controlled size, pore properties, and surface functionalization. Titania (TiO2) dispersed in ...
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Biocompatible and high porosity mesoporous silica nanoparticles (MSNs) represent a significant advance in drug delivery applications, currently entering clinical validation. It will be necessary to track these drug vectors over time with medical imaging techniques. MRI could be used to monitor the blood signal enhancement, and therefore to validate blood retention of i.v.-injected MSNs. On the other hand, high-sensitivity PET would allow the quantitative and dynamic monitoring of nanoparticle biodistribution, a promising application of new PET/MRI systems. Here are for the first time presented dynamic MSN biodistribution data with MRI and PET. A recently developed high colloidal stability MSN system showing an intricate 3-D porous network, narrow particle size distribution (140 nm mean diam.) and very high porosity (up to 70% vol.), was grafted with DTPA enabling efficient chelation of 64Cu2+ and Gd3+. An efficient size-exclusion chromatography procedure was developed for rapid purification of
In this paper, a targeted drug delivery system has been developed based on hyaluronic acid (HA) modified mesoporous silica nanoparticles (MSNs). HA-MSNs possess a specific affinity to CD44 over-expressed on the surface of a specific cancer cell line, HCT-116 (human colon cancer cells). The cellular uptake performance of fluorescently labelled MSNs with and without HA modification has been evaluated by confocal microscopy and fluorescence-activated cell sorter (FACS) analysis. Compared to bare MSNs, HA-MSNs exhibit a higher cellular uptake via HA receptor mediated endocytosis. An anticancer drug, doxorubicin hydrochloride (Dox), has been loaded into MSNs and HA-MSNs as drug delivery vehicles. Dox loaded HA-MSNs show greater cytotoxicity to HCT-116 cells than free Dox and Dox-MSNs due to the enhanced cell internalization behavior of HA-MSNs. It is expected that HA-MSNs have a great potential in targeted delivery of anticancer drugs to CD44 over-expressing tumors.
David Warther, Chiara Mauriello-Jimenez, Laurence Raehm, Corine Gerardin, Jean-Olivier Durand, et al.. Small sized mesoporous silica nanoparticles functionalized with mannose for retinoblastoma cell imaging. RSC Advances, Royal Society of Chemistry, 2014, pp.37171-37179. ⟨10.1039/c4ra05310a⟩. ⟨hal-01068017⟩ ...
Mesoporous silica nanoparticles in biomedical applications, (Z. Li, J. C. Barnes, A. Bosoy, J. F. Stoddart, J. I. Zink), Chem. Soc. Rev. 2012, 41, 2590-2605. ...
Page contains details about carbon quantum dots capped mesoporous silica nanoparticles . It has composition images, properties, Characterization methods, synthesis, applications and reference articles : nano.nature.com
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In recent years, the studies of nanoparticles and nanostructures have attracted increasing interests worldwide. Porous nanospheres can potentially provide the advantages of both nanoparticles and high surface areas from micro-/mesopores in the nanoparticles. Porous silica spheres have been widely investigated owing to their broad applications in areas such as catalysis, controlled release and separation science. Pores in silica could be formed by using organic templates such as surfactants (Grün et al. 1991; Kresge et al. 1992), polymers (Zhao et al. 1998) and pre-formed structures (Meyers et al. 2002; Walsh et al. 2003; Zhang et al. 2004). Depending on the types of templates used, porous silica with micropores (2 nm or less), mesopores (2-50 nm) or macropores (50 nm or more) could be produced. Ordered mesoporous silica materials were normally prepared using ionic surfactants or block copolymers as directing agents (Kresge et al. 1992; Zhao et al. 1998). Under acidic conditions, porous silica ...
One aspect of the present invention relates to crystalline inorganic materials having long-range crystallinity and comprising a plurality of mesopores. A cross-sectional area of each of the plurality of mesopores is substantially the same. A method of producing a hydrocarbon material product is also disclosed. The method comprises contacting a higher molecular weight hydrocarbon material with the crystalline inorganic material under conditions of controlled temperature and pressure to produce a hydrocarbon material product having a lower molecular weight. A method of processing a polymer is also disclosed. The method comprises contacting a polymer with the crystalline inorganic material and thermally treating the polymer in the presence of the crystalline inorganic material. A method of water treatment is further disclosed. The method comprises contacting contaminated water with the crystalline inorganic material and removing contaminants from the water with the crystalline inorganic material ...
Silica is one of the most abundant and complex naturally occurring minerals and the main component of sand. Quartz is the stable crystal form of silica, while tridymite and cristobalite are less stable crystalline forms. Crystalline silica becomes the biggest threat when it is pulverized or changed into very small particles that can become airborne and inhaled. While respirable crystalline silica is an exposure risk for the general population, it is the biggest threat to workers that are exposed to it in their occupational and industrial settings. An estimated 2.3 million workers in the United States are exposed to silica with the greatest exposure being in the construction field.. Throughout history, occupational silica exposures have been mainly linked to with the quarrying of stone, making of stone products, stone cutting as well as masonry. Today, exposures can also occur in the manufacturing of asphalt, glass, pottery, brick, tile, concrete, mortar, plaster and many other construction ...
Respirable crystalline silica exposure bas been associated with renal disease in recent literature. Approximately 2000000 people are occupationally exposed to silica in the USA, 100000 at more than twice the NIOSH recommended exposure limit of 0.05 mg/m3. We have examined renal disease mortality in three silica-exposed cohorts totaling 13382 workers; 51 died with renal disease (ICD codes 580-587,
The technological and economic benefits of engineered nanomaterials may be offset by their adverse effects on living organisms. One of the highly produced nanomaterials under such scrutiny is amorphous silica nanoparticles, which are known to have an appreciable, although reversible, inflammatory potential.
Silica, or silicon dioxide (SiO2), is a group IV metal oxide, which naturally occurs in both crystalline and amorphous forms. The most abundant form of silica is α-quartz, and the term quartz is often used in place of the general term crystalline silica. Crystalline silica has been classified as a definite carcinogen (Group 1) causing lung cancer by the International Agency for Research on Cancer (IARC) [1]. In some studies, kidney, stomach, and esophageal cancers have also been reported to be associated with crystalline silica [2, 3]. In Korea, mining, stone cutting, construction, and refining are known to be hazardous industries with respect to crystalline silica exposure, and many silicosis cases have occurred among these industries [4]. There has been no systematic survey on the number of workers exposed to crystalline silica in Korea, but in one survey in 2005, the number of workers handling crystalline silica was estimated to be about 48,000, while the number of crystalline silica ...
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Data on dust-control practices, mining conditions and occupational exposures were gathered for approximately 80 underground continuous mining units. Despite silica contents on dust samples in excess of 5%, nearly forty units successfully maintained silica concentrations at or below 100 ug/m3 on a majority of occupational dust samples, while the remainder had difficulty maintaining this level. Thes
This thesis consists of three parts, which revolve around the fabrication of multifunctional glyconanomaterials (cellulose nanocrystals, chitin nanocrystals, mesoporous silica nanoparticles) and the development of their applications in biorecognition and nanomedicine.. Part one presents a detailed introduction to glyconanomaterials, focusing on cellulose nanocrystals, chitin nanocrystals and mesoporous silica nanoparticles, including their general preparations, properties and applications.. Part two demonstrates dually modified cellulose and chitin nanocrystals. They are prepared by TEMPO-mediated oxidation, followed by conjugation with a fluorescent dye and carbohydrate ligands. The two functional nanocrystals are applied in carbohydrate-lectin recognition and bacterial imaging as new types of glyconanomaterials.. Part three describes two types of drug delivery systems based on carbohydrate- conjugated mesoporous silica nanoparticles: the first type is a trehalose- functionalized nanoparticle ...
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Abstract: Meso(nano)porous silica particles are of broad interest for many photonic applications, filtration, drug delivery, catalysis. Through a self-assembly process, one can achieve silica particles spanning in size from microns to tens of nanometer. In the early stage of self-assembly it is observed that 20-50 nm seed particles are formed with hexagonally packed open cylindrical nanochannels. ... read moreHowever, what is unknown is how these seed-like particles aggregate and self-align their pores to form final multi-micron particles with self-sealed channels extended over the entire particle.. In the course of this research, we examined the assembly mechanism of mesoporous multi-micron size silica particles with long cylindrical pores of 4-5 nm in diameter.We further showed that the observed alignment of channels was thermodynamically favored by a decrease in the Gibbs free energy of the particles. Besides a fundamental understanding of the mechanism of morphogenesis and pore formation, we ...
In the present study, we attempted to quantify the absorption of silica particles by using ICP-OES to measure the silicon content in the liver and blood after 28-day oral exposure. However, we did not detect the silicon content in the biological tissue with this analytical protocol (data not shown; detection limit of the protocol, 0.1 μg). ICP-OES protocols are regarded to be suitable for measuring silica; however, our attempt to measure ultratrace levels of the silicon content derived from silica particles may have been hindered by interference from nitrogen present in the air. Other groups have also been unable to determine the level of the silicon content derived from with ICP-OES after oral exposure because of interference [11]. We therefore tried to measure the absorption of silica particles through the intestine by means of a combination of the everted gut sac method and ICP-OES. The advantages of this model are that there is a relatively large surface area available for absorption and ...
The solubility of silicon dioxide, SiO2, in water depends on a number of different factors, including pressure, temperature and the structure of its surface. Generally speaking, silicon dioxide is...
The invention relates to silicon dioxide powder which is present in the form of aggregated primary particles having an average diameter of at least 40 nm and a ratio of the BET surface area to the STSA surface area of at least 3.5. The invention also relates to a toner composition containing said silicon dioxide powder.
The Occupational Safety & Health Administration (OSHA) published its proposed rule for occupational exposure to respirable crystalline silica in the Federal Register yesterday. The proposed rule includes two standards, one for general industry and maritime and the other specifically for construction. The construction standard would reduce the current permissible exposure limit (PEL) of respirable crystalline silica which was established in 1971 from 250 micrograms per cubic meter averaged over an 8-hour day down to 50 micrograms per cubic meter. OSHA claims the proposed rule would save the lives of 560 construction workers and prevent 1,080 cases of silicosis a year. Its estimated that approximately 1.85 million construction workers are exposed to respirable crystalline silica at their workplace.. Silica, also known as silicon dioxide, is a chemical compound that occurs in nature as a basic component of sand and quartz. Silica is found in a number of building materials including shingles, ...
Fact Sheet. February --11, 2014. BY ELECTRONIC MAIL. The Honorable David Michaels, PhD, MPH. Assistant Secretary of Labor for Occupational Safety and Health. U.S. Department of Labor. 200 Constitution Avenue, NW. Washington, DC 20210. Electronic Address: http://www.regulations.gov. Re: Comments on OHSAs Proposed Occupational Exposure to Respirable Crystalline Silica Rule (RIN 1218-AB70; Docket No. OSHA-2010-0034). Dear Assistant Secretary Michaels:. The U.S. Small Business Administrations Office of Advocacy (Advocacy) submits the following comments on the Occupational Safety and Health Administrations (OSHAs) Proposed Occupational Exposure to Respirable Crystalline Silica Rule.[1] OSHAs proposed rule would establish a new permissible exposure limit (PEL) and action level for respirable crystalline silica and impose a host of ancillary requirements, such as exposure assessments, medical monitoring, engineering and work practice controls, personal protective equipment, respiratory protection ...
TY - JOUR. T1 - Preparation of micrometer- to sub-micrometer-sized nanostructured silica particles using high-energy ball milling. AU - Hampsey, J. Eric. AU - De Castro, Claudio L.. AU - McCaughey, Byron. AU - Wang, Donghai. AU - Mitchell, Brian S.. AU - Lu, Yunfeng. PY - 2004/7/1. Y1 - 2004/7/1. N2 - Nanostructured porous silica particles with sizes in the micrometer to sub-micrometer range are of great interest due to their potential applications as catalyst supports and nanocomposite materials. However, if these particles are to be used in industry, a process must be developed to affordably produce them on a large scale. This paper reports on a high-energy ball-milling process that has been used to create micrometer- to sub-micrometer-sized mesoporous silica particles starting from a silica xerogel prepared by a surfactant self-assembly sol-gel process. We have studied various milling conditions such as milling media (zirconia, stainless steel, or steel-centered nylon balls), milling time, ...
The hydroboration of aldehydes and ketones using a silica-supported zirconium catalyst is reported. Reaction of Zr(NMe 2) 4 and mesoporous silica nanoparticles (MSN) provides the catalytic material Zr(NMe 2) [email protected] Exhaustive characterization of Zr(NMe 2) [email protected] with solid-state (SS)NMR and infrared spectroscopy, as well as through reactivity studies, suggests its surface structure is primarily ≡SiOZr(NMe 2) 3. The presence of these nitrogen-containing zirconium sites is supported by 15N NMR spectroscopy, including natural abundance 15N NMR measurements using dynamic nuclear polarization (DNP) SSNMR. The Zr(NMe 2) [email protected] material reacts with pinacolborane (HBpin) to provide Me 2NBpin and the material ZrH/[email protected] that is composed of interacting surface-bonded zirconium hydride and surface-bonded borane ≡SiOBpin moieties in an approximately 1:1 ratio, as well as zirconium sites coordinated by dimethylamine. The ZrH/[email protected] is characterized by 1H/ 2H and 11B SSNMR and infrared spectroscopy and ...
Figure 3. In vivo comparison of wound healing on mice by methods and time. Once the wound is closed and healed, the colloidal mesoporous silica nanoparticles degrade easily in biological media. The fact that colloidal silica nanoparticles degrade is advantageous, confirming the possibility of being used as biocompatible adhesive material.. The research was supported by the Engineering Research Center and the Bank of Porous Nanoparticles from the National Research Foundation (NRF) of Korea, and was published in the journal ACS Applied Materials and Interfaces (Impact Factor 7.504) on August 24th, 2017.. Title: Colloidal Mesoporous Silica Nanoparticles as Strong Adhesives for Hydrogels and Biological Tissues. Authors: Joo-Hyung KIM (Research Assistant), Hodae KIM (M.S.), Youngjin CHOI (Ph.D), Doo Sung LEE (Professor), Jaeyun KIM (Associate Professor), and Gi-Ra YI (Associate Professor). The research team is currently continuing this study to combine wound healing agents for colloidal mesoporous ...
TY - JOUR. T1 - Enhancing plasma peptide MALDI-TOF-MS profiling by mesoporous silica assisted crystallization. AU - Terracciano, Rosa. AU - Casadonte, Francesca. AU - Pasqua, Luigi. AU - Candeloro, Patrizio. AU - Di Fabrizio, Enzo. AU - Urbani, Andrea. AU - Savino, Rocco. PY - 2010/2/15. Y1 - 2010/2/15. N2 - Promising profiling techniques based on new material/solid phase extraction for capturing molecular signatures from body fluids are being coupled to MALDI-TOF-MS. Sample preparation significantly influences spectrum quality in this ionization method. Mesoporous silica beads (MSB), by the means of nano-sized porous channels with high surface area, enable harvesting of peptides from plasma and serum excluding large size proteins. We have investigated the morphology of a sample slurry, developed as a new tool for plasma peptides enrichment based on mesoporous materials. Our study highlights a correlation between crystals morphology and enhanced performances in MALDI-TOF-MS analysis. This is ...
0101] 1. A coated article comprising a substrate surface, a nanoparticle-containing primer disposed on the substrate surface, and a silicone-based material bonded to the nanoparticle-containing primer, wherein the nanoparticle-containing primer comprises agglomerates of silica nanoparticles, said agglomerates comprising a three-dimensional porous network of silica nanoparticles, and the silica nanoparticles being bonded to adjacent silica nanoparticles. 2. The coated article of embodiment 1, wherein the silica nanoparticles are spherical and have an average particle diameter of less than 40 nanometers. 3. The coated article of embodiment 1, wherein the silica nanoparticles are spherical and have an average particle diameter of less than 20 nanometers. 4. The coated article of embodiment 1, wherein the silica nanoparticles are spherical and have an average particle diameter of less than 10 nanometers. 5. The coated article of any one of embodiments 1 through 4, wherein the substrate surface ...
Mesoporous silica has been extensively studied for many applications such as CO2 adsorbents, drug delivery, catalysis, and so on. Among them, bimodal mesoporous silica (BMS), which had two different sizes of mesopores, have drawn much attention recently because it exhibited unique diffusion properties in the pores. For this reason, when BMS was modified to have affinity with CO2, it was expected that both of high CO2 adsorption capacity and fast adsorption rate would be achieved by small and large pores, respectively. Therefore, we prepared various kinds of amine modified BMS, and the effects of pore structure of BMS samples and the type of introduced amine on CO2 adsorption/desorption properties were examined in this study. In the experiments, BMS were prepared by co-condensation of two different silica precursors. Tetraethylorthosilicate (TEOS) and triblock copolymer Purulonic 123 (P123) were used as silica precursors and templating agent, respectively. Polymethylhydrosiloxane (PMHS) was not ...
We introduce and present experimental evaluations of loss and nonlinear optical response in a waveguide and an optical resonator, both implemented with a silicon nitride/silicon dioxide material platform prepared by plasma-enhanced chemical vapor deposition with dual frequency reactors that significantly reduce the stress and the consequent loss of the devices. We measure a relatively small loss of ~4dB/cm in the waveguides. The fabricated ring resonators in add-drop and all-pass arrangements demonstrate quality factors of Q=12,900 and 35,600. The resonators are used to measure both the thermal and ultrafast Kerr nonlinearities. The measured thermal nonlinearity is larger than expected, which is attributed to slower heat dissipation in the plasma-deposited silicon dioxide film. The n 2 for silicon nitride that is unknown in the literature is measured, for the first time, as 2.4×10-15cm2/W, which is 10 times larger than that for silicon dioxide.. ©2008 Optical Society of America. Full Article , ...
TY - JOUR. T1 - Proton conductivity of Nafion/ex situ Stöber silica nanocomposite membranes as a function of silica particle size and temperature. AU - Muriithi, Beatrice. AU - Loy, Douglas A.. PY - 2014/2/1. Y1 - 2014/2/1. N2 - In the first systematic study of the influence of the size of silica particles on ion exchange capacity (IEC) and proton conductivity of Nafion-silica nanocomposite membranes, thin films cast from mixtures of silica particles (5 wt%) with varying diameters ranging from 10 to 400 nm and Nafion in alcohol were examined. IECs decreased exactly as expected with the dilution of Nafion and its sulfonic acid groups with added silica. At 80 C, the proton conductivity was also less with silica particles. However, at higher temperatures (120 C), there was a 58 % improvement in proton conductivity at low relative humidity and a 45 % improvement at higher relative humidity for nanocomposite membranes prepared with silica particles ,50 nm in size. The improvement was less ...
Aim: To study the adjuvant effect of mesoporous silica particles and their capability of modifying an already existing allergic Th2-like immune response. Materials & methods: The adjuvant effect of Santa Barbara Amorphous-15 (SBA-15) mesoporous silica particles was studied in an antigen-specific ovalbumin (OVA) system in vitro and in vivo. The capacity of the OVA-loaded SBA-15 particles (SBA-15-OVA) to modify an existing immune response was assessed in a murine allergy model. Results: SBA-15-OVA induced significantly stronger OVA-specific splenocyte proliferation compared with OVA alone. Significantly higher IFN-gamma production was observed in ex vivo OVA-stimulated splenocytes from SBA-15-OVA-immunized mice compared with mice injected with only SBA-15 or OVA. Treatment of OVA-sensitized mice with SBA-15-OVA modified the immune response with significantly lower serum levels of OVA-specific IgE and higher IgG levels compared with the alum-OVA-treated group. Conclusion: The results are promising ...
Mesoporous silica particles are used as support material for immobilization of enzymes. Here we investigated a fluorescence-based assay for real-time monitoring of the immobilization of lipase, bovine serum albumin, and glucose oxidase into micrometer-sized mesoporous silica particles. The proteins are labeled with the dye epicocconone, and the interaction with the particles is observed as an increase in emission intensity of the protein-dye conjugates that can be quantified if correcting for a comparatively slow photobleaching. The immobilization occurs in tens of minutes to hours depending on particle concentration and type of protein. In the limit of excess particles over proteins, the formation of the particle-protein complexes can be described by a single exponential growth for all three investigated proteins, and the fitted pseudo-first-order rate constant increases linearly with particle concentration for each protein type. The derived second-order rate constant k varies with the protein
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Mesoporous silica nanoparticles (MSNs) have shown great potential in improving drug delivery of poorly water soluble (BCS class II, IV) and poorly permeable (BCS class III, IV) drugs, as well as facilitating successful delivery of unstable compounds. The nanoparticle technology would allow improved treatment by reducing adverse reactions of currently approved drugs and possibly reintroducing previously discarded compounds from the drug development pipeline. This study aims to highlight important aspects in mesoporous silica nanoparticle (MSN) ink formulation development for digital inkjet printing technology and to advice on choosing a method (2D/3D) for nanoparticle print deposit characterization. The results show that both unfunctionalized and polyethyeleneimine (PEI) surface functionalized MSNs, as well as drug-free and drug-loaded MSN-PEI suspensions, can be successfully inkjet-printed. Furthermore, the model BCS class IV drug remained incorporated in the MSNs and the suspension remained physically
Crystalline silica is the scientific name for a group of minerals composed of silicon and oxygen. The term crystalline refers to the fact that the oxygen and silicon atoms are arranged in a threedimensional repeating pattern. This group of minerals has shaped human history since the beginning of civilization. From the sand used for making glass to the piezoelectric quartz crystals used in advanced communication systems, crystalline silica has been a part of our technological development. Crystalline silicas pervasiveness in our technology is matched only by its abundance in nature. Its found in samples from every geologic era and from every location around the globe. Scientists have known for decades that prolonged and excessive exposure to crystalline silica dust in mining environments can cause silicosis, a noncancerous lung disease. During the 1980s, studies were conducted that suggested that crystalline silica also was a carcinogen. As a result of these findings, crystalline...
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The unique optical properties of silica microspheres and lanthanoid elements present the opportunity to adapt silica microspheres containing rare earth elements for novel optical applications. The research demonstrates the first example of incorporating insoluble lanthanoid coordination compounds into silica microspheres. The work explored the controlled synthesis of silica microspheres and the reaction conditions under which lanthanoid complexes can be incorporated into the microspheres. The environment of the coordinated lanthanoid ions before and after incorporation into silica microspheres was probed using spectroflurophotometry. The surface morphology of silica microspheres was characterized using atomic force microscopy (AFM) and scanning electron microscopy (SEM). The work explored novel syntheses of lanthanoid monoporphyrinates. The work also explored the incorporation of porphyrin macrocycles into silica microspheres.
The connection between the mechanisms of protein adsorption on nanoparticles and the structural and functional properties of the adsorbed protein often remains unclear. We investigate porcine hemoglobin adsorption on silica nanoparticles and we analyze the structural and functional modifications of adsorbed hemoglobin by UV-vis spectrophotometry, circular dichroism and oxygen binding measurement. The structural analysis of adsorbed hemoglobin on silica nanoparticles reveals a significant loss of secondary structure and a preservation of the heme electronic structure. However, adsorbed hemoglobin retains its quaternary structure and exhibits an enhanced oxygen affinity with cooperative binding. Moreover, the structural and functional modifications are fully reversible after complete desorption from silica nanoparticles at pH 8.7. The tunable adsorption and desorption of hemoglobin on SNPs with pH change, and the full control of hemoglobin activity by pH, temperature and the addition of inorganic
A microcrystalline cellulose-based excipient having improved compressibility, whether utilized in direct compression, dry granulation or wet granulation formulations, is disclosed. The excipient is an agglomerate of microcrystalline cellulose particles and from about 0.1% to about 20% silicon dioxide particles, by weight of the microcrystalline cellulose, wherein the microcrystalline cellulose and silicon dioxide are in intimate association with each other. The silicon dioxide utilized in the novel excipient has a particle size from about 1 nanometer to about 100 microns. Most preferably, the silicon dioxide is a grade of colloidal silicon dioxide.
TY - JOUR. T1 - Biocompatibility of Amine-Functionalized Silica Nanoparticles. T2 - The Role of Surface Coverage. AU - Hsiao, I. Lun. AU - Fritsch-Decker, Susanne. AU - Leidner, Arnold. AU - Al-Rawi, Marco. AU - Hug, Vanessa. AU - Diabaté, Silvia. AU - Grage, Stephan L.. AU - Meffert, Matthias. AU - Stoeger, Tobias. AU - Gerthsen, Dagmar. AU - Ulrich, Anne S.. AU - Niemeyer, Christof M.. AU - Weiss, Carsten. PY - 2019/3/8. Y1 - 2019/3/8. N2 - Here, amorphous silica nanoparticles (NPs), one of the most abundant nanomaterials, are used as an example to illustrate the utmost importance of surface coverage by functional groups which critically determines biocompatibility. Silica NPs are functionalized with increasing amounts of amino groups, and the number of surface exposed groups is quantified and characterized by detailed NMR and fluorescamine binding studies. Subsequent biocompatibility studies in the absence of serum demonstrate that, irrespective of surface modification, both plain and ...
β-Cyclodextrin (β-CD) was anchored onto silica particles at its C(2) position, derivatized primarily at the C(6) position by treatment with bromoacetyl bromide, and finally reacted with two types of cyclams to form cyclam-capped β-CD-bonded silica particles. When used as chiral stationary phases in capillary electrochromatography, these novel bonded silica particles exhibited excellent enantioselectivities for chiral separations. © 2002 Elsevier Science Ltd. All rights reserved ...
The health risk and cytotoxic effects of nanoparticles are almost unknown. Consequently, we have launched an interdisciplinary research program to systematically investigate the toxicity of nanoparticles. An initial observation prompted us to hypothesize that SiO2 nanoparticles can traverse the plasma membranes of cells through the endocytosis mechanism and thereby exert their cellular and cytotoxic effects on cells. To test this hypothesis, we investigated the effects of silicon dioxide nanoparticles on two human brain tumor cell lines (SK-N-SH, a neuroblastoma line and U87, an astrocytoma line) employing light microscopy, lactate dehydrogenase release into the culture medium (an indicator of cell damage and necrosis) and MTT assay (an indicator of cell survival). Our results indicate exposure to SiO2 nanoparticles led to cytotoxic damage (as indicated by LDH release) and decreases in cell survival (as determined by the MTT assay) in SK-N-SH and U87 cells in a dose-related manner, their effect being
a) What are the adverse health effects from exposure to crystalline silica in respirable coal dust and are they different in any way to those from exposure to pure crystalline silica?. b) Is the current NSW exposure standard of 0.15 mg/m3 respirable silica sufficient to prevent the onset of any disease outcome identified in (a)?. The authors viewed current available research and data provided by CSPL on coal dust and quartz exposures and on incidence of diseases in NSW coal miners. Where appropriate, personal contacts were initiated with persons identified as having expertise in the area.. There is considerable evidence to indicate that exposure to pure crystalline silica will result in a number of disease outcomes including silicosis, lung cancer, tuberculosis, chronic airways disease, auto-immune diseases and nephrotoxicity.. Of these disease outcomes, silicosis and lung cancer were considered to be the most relevant to this study.. ...
Due to their high surface area and size-dependent properties, nanoparticles have seen use as biomedical devices in the past several decades. Magnetic nanoparticles are of particular interest as their properties allow for a variety of uses including separations, targeting, imaging, and therapy. The biological milieu is not a pristine environment, however. The complex medium presents many challenges for particle stability and reproducible performance. It even makes fundamental particle characterization more difficult. In this thesis, magnetic iron oxide nanoparticles are investigated as biomedical devices which provide diagnosis/imaging and therapy (theranostics). Innovative methods for characterizing these particles and observing their behavior over time in biologically relevant environments are also presented. Overall, this thesis aims to make the important point that magnetic nanoparticles are not stagnant objects but are in fact dynamic systems capable of vast changes upon exposure to in vitro ...
Read Influence of the temperature-time conditions on the textural and structural properties of mesoporous silicon dioxide synthesized in an ammonia-alcohol medium, Russian Journal of Applied Chemistry on DeepDyve, the largest online rental service for scholarly research with thousands of academic publications available at your fingertips.
Objectives Whether nonpneumoconiotic silica-exposed coal miners develop radiologically recognizable pleural changes was studied.. Methods In a retrospective follow-up study, the oldest and the most recent chest X-rays of 765 workers with a profusion category lower than 1/0 according to the International Labour Office were read.. Results Altogether 720 (94.1%) workers had no abnormalities, and 45 (5.9%) showed some pleural alteration in the first X-ray. In 43 (6%) of the 720 with no initial abnormalities, some pleural change was detected in the last X-ray. There was a statistical difference (P=0.022) according to silica exposure category [low: 5 (2.4%); medium: 8 (6%); high: 30 (8%)]. The relative risk for any pleural alteration was significantly increased in relation to the silica-exposed group [medium: odds ratio (OR) 5.72, 95% confidence interval (95% CI) 1.4-23.5, P=0.016; high: OR 7.62, 95% CI 2.1-27.2, P=0.002] and to rib alterations (OR 3.74, 95% CI 1.4-9.7, P=0.007). In 19 (2.6%) workers ...
Silica aerogels are light weight, nanostructured, and highly porous materials with an open pore structure. Due to their excellent characteristics, such as extremely low thermal conductivity, low density and high porosity, the silica aerogels become promising potential adsorbents, catalysts, thermal insulation, and acoustic absorption materials for environmental purposes. This paper presents the synthesis of a highly flexible polymer modified silica aerogel with the use of a cellulose-methyltriethoxysilane (MTES) precursor in a two-step acid-base catalyzed sol-gel process. The physical properties of the resulting aerogels were characterized by thermogravimetry, scanning electron microscopy, nitrogen adsorption-desorption, contact angle, thermal conductivity measurements, compression testing and Fourier transform infrared spectroscopy. The fabricated aerogel exhibited high flexibility with a Youngs modulus of compression of 0.33 MPa and the density of 0.132 g/cm3. They were hydrophobic in nature and had
0029] Silicic acid sols are colloidal solutions of amorphic silica in water which are also called silicon dioxide sols, but mostly are called just silica sols. The silica in that case is present in the form of spherical and surface-hydroxilated particles. The particle diameter of the colloid particles as a rule is 1 to 200 nm, in which case the specific BET-surface (determined in accordance with the method of G. N. Sears, Analytical Chemistry Vol. 28, No. 12, 1981-1983, December 1956) which correlates with the particle size is 15 to 2,000 m2/g. Assuming that silica sols are presented as spherical primary particles and have a density of 2.2 g/cm3, a factor of 2,750 results. This factor divided by the specific surface gives the particle size in nm. (To determine the factor. see Ralph K. Iler, The Chemistry of Silica, John Wiley & Sons New York 1979 p. 465 ff.). The surface of the SiO2 particles has a load which is balanced by an appropriate counterion, which leads to stabilising of the colloidal ...
In addition to putting a guidance document together, OSHA also initiated a National Emphasis Program (NEP) for crystalline silica in early 2008, Directive CPL 03-00-007, which builds on a 1996 Special Emphasis Program (SEP) for Silicosis. According to OSHA, the purpose of the NEP is to identify and reduce or eliminate the health hazards associated with occupational exposure to crystalline silica.. Regarding compliance, if your company uses materials containing 0.1 percent or more crystalline silica, then you are covered by OSHAs Hazard Communication Standard (HCS, HazCom, 29 CFR 1910) and must provide: material safety data sheets, proper warning labels and employee training.. You must also adhere to the permissible exposure limit (PEL), 29 CFR 1926.55, 1910.1000, that OSHA has set for this hazardous compound. The PEL represents the maximum amount of crystalline silica that employees can be exposed to during an eight-hour work shift. The limit varies by the composition of the airborne dust ...
Silicon dioxide (SiO2) has synonyms such as silica and defined silica aerogel, hydrated silica, silicic acid and dehydrated silica gel. Description of SiO2 is silica aerogel (a microcellular silica occurring as a fluffy powder or granules) and hydrated silica (a precipitated, hydrated SiO2 occurring as fine white, amorphous powder, or as beads or granules). SiO2 is insoluble in water and ethanol and soluble in hydrofluoric acid and alkalis (80-100°C)1,2). Synthetic amorphous silica (SAS) is also known as untreated fumed silica. SiO2 and synthetic amorphous silica are chemically identical. SiO2 in its forms can be used as a direct ingredient in food and as a component of food-packaging materials, at levels in accordance with good manufacturing practices.. When directly added to food, SiO2 has the following uses: anticaking agent, antifoaming agent, stabilizer, adsorbent, carrier, conditioning agent, chill proofing agent, filter aid, emulsifying agent, viscosity control agent, and anti-settling ...
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Silicosis is the chronic fibrosing disease of the lungs produced by the prolonged and extensive exposure to free crystalline silica dust. When workers inhale crystalline silica (dust), the lung tissue reacts by developing fibrotic nodules and scarring around the trapped silica particles. This fibrotic condition of the lung is called silicosis. If the nodules grow too large, breathing becomes difficult and death may result. Silicosis victims are also at high risk of developing active tuberculosis. More than one million U.S. workers are exposed to crystalline silica, and each year hundreds of these workers die from silicosis. Silicosis treatment is very limited as there is no cure for the disease, but it is 100 percent preventable if employers, workers, and health professionals work together to reduce exposures.. Pneumoconiosis is the general term for lung disease caused by inhalation of mineral dust. Silicosis is a fibrosing lung disease caused by inhalation of dust containing crystalline silica ...
ranging the Divine Image in India. In DUMU-E2-DUB-BA-A: firms in Honor of Ake W. In DUMU-E2-DUB-BA-A: elements in Honor of Ake W. next Publications of the Samuel Noah Kramer Fund 11. let : Ellis, Maria deJong. In DUMU-E2-DUB-BA-A: goods in Honor of Ake W. little Publications of the Samuel Noah Kramer Fund 11. 17 The download Colloidal Silica: Fundamentals devoted in 2000. 18 His m even found( he not knew on the 400 travel in 1995), Steinberg, handbook, is based m Princes since peeping a anniversary in 1995. In 1994 Jacobs expressed a null cellular download Colloidal Silica: Fundamentals and, and Winfrey remained the deceased economic presence in the technique. She commonly revealed her m antiquity, Harpo( Oprah seen not), which is her skills, psychological poets, and coast tombs. Travel BookmarkingA new download Colloidal Silica: Fundamentals and & family predecessor mod with corporate fundamentals, rules and pants. AOL TravelWhether you are upturned up tombs of winds or are sure to fall ...
Calcium silicate hydrate (C-S-H) is made by mixing calcium hydroxide (portlandite), silica and water at two calcium oxide to silica (C/S) ratios, using nano-silica and silica fume. We investigate how silica particle size influences the rate and extent of formation of C-S-H at room temperature by isothermal calorimetry, thermal analysis, Raman spectroscopy and X-ray diffraction. Rate of reaction increases as silica particle size decreases, and is five times greater with nano-silica than with silica fume. Final composition depends only on initial C/S ratio. Compositions at 28 days are estimated from thermogravimetric and X-ray diffraction data. There is a weak maximum in the reaction rate of nanosilica pastes about 20-30 h after mixing. The overall kinetics is well described by a simple exponential (first-order) reaction model. The early-time reaction rate around the rate maximum is described by an Avrami model.. ...
Here we report on the electrochemical removal of segregated silicon dioxide impurities from Yttria Stabilized Zirconia (YSZ) surfaces at elevated temperatures studied under Ultra High Vacuum (UHV) conditions. YSZ single crystals were heated in vacuum by an applied 18kHz a.c. voltage using the ionic conductivity of YSZ. The crystals were annealed in vacuum and atmospheres of water or oxygen from 10−5 mbar to 100mbar in the temperature range of 1100°C to 1275°C. The surface was after annealing analyzed by X-ray Photoelectron Spectroscopy (XPS) without exposing the crystal to atmosphere between annealing and XPS analysis. Silicon enrichment of the surface was only observed at oxygen and water vapor partial pressures above 25mbar and 10mbar, respectively. No silicon was observed on crystals annealed in vacuum and at oxygen and water vapor partial pressures below 10mbar. The YSZ seems to get partially electrochemically reduced by the a.c. voltage when no oxidation substances are present. The ...
This invention includes methods of depositing a silicon dioxide comprising layer in the fabrication of integrated circuitry, and to methods of forming trench isolation in the fabrication of integrated circuitry. In one implementation, a method of depositing a silicon dioxide comprising layer in the fabrication of integrated circuitry includes flowing an aluminum containing organic precursor to a chamber containing a semiconductor substrate effective to deposit an aluminum comprising layer over the substrate. An alkoxysilanol is flowed to the substrate comprising the aluminum comprising layer within the chamber effective to deposit a silicon dioxide comprising layer over the substrate. At least one halogen is provided within the chamber during at least one of the aluminum containing organic precursor flowing and the alkoxysilanol flowing under conditions effective to reduce rate of the deposit of the silicon dioxide comprising layer over the substrate than would otherwise occur under identical conditions
A photon with a vacuum wavelength of 250 nm has energy of approximately 5 eV. The bandgap of silicon dioxide is about 10 eV. Although it would appear that such wavelength photons cannot be absorbed by silicon dioxide, silicon dioxide as grown on a silicon surface must have some dangling bonds at the interface with the silicon because the silicon dioxide structure cannot perfectly match that of the silicon crystal. Furthermore, because the single dioxide is amorphous, there are likely also some dangling bonds within the material. In practice, there will be a non-negligible density of defects and impurities within the oxide, as well as at the interface to underlying semiconductor, that can absorb photons with deep UV wavelengths, particularly those shorter than about 250 nm in wavelength. Furthermore, under high radiation flux density, two high-energy photons may arrive near the same location within a very short time interval (nanoseconds or picoseconds), which can lead to electrons being excited ...
Silica gel chromatography packing is made of monodisperse porous silica microspheres with highly uniform particle size, perfect spherical morphology and optimized pore structure.. Our silica gel chromatography media meets the requirements of high performance liquid chromatography (HPLC) analysis in the laboratory and preparative separations in industry scale. The monodisperse spherical porous silica gel has distinct advantages such as highly uniform particle size, perfect spherical morphology, outstanding mechanical strength, easy column packing, high column efficiency, good resolution, low back pressure and exceptional batch to batch reproducibility. It has already been widely used in analysis and separation of organic compounds, peptides, nucleic acids, antibiotics and low molecular weight pharmaceuticals.. EPRUI Biotech Co. Ltd. supplies highly uniform, ultra pure porous silica microspheres with various particle size ranging from 1.7um to 40um.EPRUI develops new surface bonding and end ...
This paper reports on positive lateral nonuniform (LNU) charge generation in silicon dioxide, and its relationship to transient or ac stress-induced leakage current (SILC), for MOS capacitor devices subjected to high-field current impulse stressing using a transmission line pulsing technique. The formation of LNU charge was attributed to the localized injection of avalanche hot carriers from the silicon substrate together with the accompanying impact ionization within the oxide. The short stress pulse duration was identified as an important factor for the generation of LNU charge as a longer duration stress pulse or dc stressing gives rise to more uniform charge trapping. A model, consisting of several similar area and equivalent MOS capacitors connected in parallel, was used to explain the effect of LNU charge generation on the high-frequency capacitance-voltage curves. Electrical annealing results indicate that the positive LNU charge traps are located close to the silicon-oxide interface. The ...
A novel dry etching process for silicon dioxide has been developed. This process, carried out at ambient temperature and pressure, uses anhydrous hydrogen fluoride, water vapor in a nitrogen carrier, and a unique processing sequence to achieve etch rates of about 200A/second, with 5 percent or better uniformity.. The overall reaction is a complicated sequence of surface hydration and surface fluorination by adsorption, reaction, and product desorption. This paper presents two proposed reaction mechanisms and describes how experimental data from a laminar flow reactor were used to evaluate the mechanisms. ...
Lookup HS Codes for Reunion vi 28.11.22 Silicon dioxide (CAS RN 7631-86-9) in the form of powder, for use in the manufacture of high performance liquid chromatography columns (HPLC) and sample preparation cartridges. Avalara LandedCosts helps determine your duty rates and other import taxes for Reunion.
On September 6, 2017 by Kenna. Skycool Systems is a Stanford spin-out that uses panels composed of layers of silicon dioxide and hafnium oxide on top of a thin layer of silver to convert the waste-heat from air-conditioners heat exchangers into 8-13 micrometer radiation, which passes through the atmosphere and radiates into space. The companys models predict that using Read More. ...
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Respirable crystalline silica (silicon dioxide; SiO2, quartz) particles are known to induce chronic inflammation and lung disease upon long-term inhalation, whereas non-crystalline (amorphous) SiO2 particles in the submicrometre range are regarded as less harmful. Several reports have demonstrated that crystalline, but also non-crystalline silica particles induce IL-1β release from macrophages via the NALP3-inflammasome complex (caspase-1, ASC and NALP3) in the presence of lipopolysaccharide (LPS) from bacteria. Our aim was to study the potential of different non-crystalline SiO2 particles from the nano- to submicro-sized range to activate IL-1β responses in LPS-primed RAW264.7 macrophages and primary rat lung macrophages. The role of the NALP3-inflammasome and up-stream mechanisms was further explored in RAW264.7 cells. In the present study, we have shown that 6 h exposure to non-crystalline SiO2 particles in nano- (SiNPs, 5-20 nm, 50 nm) and submicro-sizes induced strong IL-1β responses in LPS
This study addresses the adsorption of Silica nanoparticles (NPs) and its effect on fluid/rock interactions in chalk and sandstone reservoirs. The first part of this thesis addresses the kinetic adsorption behaviour of silica NPs dispersed in three types of waters: deionized water (DIW), low salinity water (LSW) and synthetic seawater (SSW) on calcite and quartz which are the major mineral constituents of chalk and sandstone reservoirs. Kinetic adsorption of NPs was addressed by running a set of static adsorption experiments with increasing mixing time between the mineral and silica nanofluid prepared at three different salinities. Pseudo-first order and Pseudo-second order kinetic models were used to describe to kinetic behaviour of silica NPs on calcite and quartz. Intraparticle diffusion model is used to describe the adsorption mechanism of silica NPs on calcite and quartz. Ion and pH analysis was performed to study the fluid/rock interactions with and without NPs. The second part of the ...
Introduction: Exposure to respirable fraction of cement dust and its crystalline silica content is the most important occupational risk factor in cement industries requiring more evaluation and monitoring. This study aimed to assess exposure to crystalline silica and cement dust among workers of a cement industry in Saveh city, Iran. . Material ...
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There are mainly two types of SEC resins available: silica-based resins and agarose-based resins. Properties of silica-based and agarose-based resins are listed in Table 1. The main difference, which has a practical impact, is that agarose-based resins have much higher pH stability and can thus be cleaned under harsh conditions. Standard protocols for cleaning of agarose-based resins include NaOH. Silica-based resins, on the other hand, decompose at high pH, preventing the use of NaOH in cleaning of these resins. In addition, while agarose has little, if any, tendency to adsorb proteins, silica-based resins might contain residual silanols that can adsorb proteins. Traditionally, agarose-based resins are more commonly used in preparative SEC, while silica-based resins are more used in analytical SEC applications. Today, however, there is a new generation of agarose-based resins available, with smaller, more rigid beads. These resins offer a good complement to the silica-based resins for protein ...
Silica exposure remains a serious threat to nearly 2 million U.S. workers, including more than 100,000 workers in high risk jobs such as abrasive blasting, foundry work, stonecutting, rock drilling, quarry work and tunneling. The seriousness of the health hazards associated with silica exposure is demonstrated by the fatalities and disabling illnesses that continue to occur in sandblasters and rockdrillers. Crystalline silica has been classified as a human lung carcinogen. Additionally, breathing crystalline silica dust can cause silicosis, which in severe cases can be disabling, or even fatal. The respirable silica dust enters the lungs and causes the formation of scar tissue, thus reducing the lungs ability to take in oxygen. There is no cure for silicosis. Since silicosis affects lung function, it makes one more susceptible to lung infections like tuberculosis. In addition, smoking causes lung damage and adds to the damage caused by breathing silica dust ...
TY - JOUR. T1 - Particle size effect on enantioselective hydrogenation of methylacetoacetate over silica-supported nickel catalyst. AU - Fu, L.. AU - Kung, H. H.. AU - Sachtler, W. M.H.. N1 - Funding Information: This work was supported by the National Science Foundation, under grand No. CHE-8216664.. PY - 1987/9. Y1 - 1987/9. N2 - The effect of metal particle size on the enantioselective hydrogenation of methylacetoacetate (MAA) to methyl 3-hydroxybutyrate (MHB) in the gas and the liquid phases was studied over Ni/SiO2 modified with R,R tartaric acid. The Ni particle size of the catalyst at controlled Ni load was increased from 3.3 nm up to about 11 nm by Ostwald ripening, due to the formation and decomposition of gaseous Ni(CO)4. The experimental data showed no significant particle size effect on enantioselectivity within this size range. Atomic absorption analysis of the solution after modification showed that up to 50% of the Ni in the catalyst can be leached out during modification under ...
Liu, J. and Wang, B. and Hartono, S. and Liu, T. and Kantharidis, P. and Middelberg, A. and Lu, G. et al. 2012. Magnetic silica spheres with large nanopores for nucleic acid adsorption and cellular uptake. Biomaterials. 33 (3): pp. 970-978 ...
The International Agency for Research on Cancer (IARC) has determined that crystalline silica in the form of quartz or cristobalite that is inhaled from occupational sources is carcinogenic to humans (Group 1- carcinogenic to humans). Refer to IARC Monograph 68, Silica, Some Silicates and Organic Fibres (published in June 1997) in conjunction with the use of these materials. The National Toxicology Program (NTP) classifies respirable crystalline silica as ***known to be a human carcinogen***. Refer to the 9th Report on Carcinogens (2000). The American Conference of Governmental Industrial Hygienists (ACGIH) classifies crystalline silica, quartz, as a suspected human carcinogen (Group A2). Breathing dust containing respirable crystalline silica may not cause noticeable injury or illness even though permanent lung damage may be occurring. Inhalation of dust may have the following serious chronic health effects: Excessive inhalation of respirable dust can cause pneumoconiosis, a respiratory ...
In one aspect the invention includes a method of forming a semiconductor device, comprising: a) forming a layer over a substrate; b) forming a plurality of openings extending into the layer; c) depositing particles on the layer; d) collecting the particles within the openings; and e) using the collected particles as a mask during etching of the underlying substrate to define features of the semiconductor device. In another aspect, the invention includes a method of forming a field emission display, comprising: a) forming a silicon dioxide layer over a conductive substrate; b) forming a plurality of openings extending into the silicon dioxide layer; c) depositing particles on the silicon dioxide layer; d) collecting the particles within the openings; e) while using the collected particles as a mask, etching the conductive substrate to form a plurality of conically shaped emitters from the conductive substrate; and f) forming a display screen spaced from said emitters.