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## THE ROLE OF COLLOIDAL SILICON DIOXIDE IN THE ENHANCEMENT OF THE DRYING OF HERBAL PREPARATIONS IN SUSPENDED STATE

SOUZA, C. R. F.; DONIDA, M. W.; ROCHA, S. C. S.; OLIVEIRA, W. P.
Fonte: TAYLOR & FRANCIS INC Publicador: TAYLOR & FRANCIS INC
Tipo: Artigo de Revista Científica
ENG
Relevância na Pesquisa
68.261685%
Recently, some research groups have been developing studies aiming to apply spouted beds of inert particles for production of dried herbal extracts. However, mainly due to their complex composition, several problems arise during the spouted bed drying of herbal extracts such as bed instability, product accumulation, particle agglomeration, and bed collapse. The addition of drying carriers, like colloidal silicon dioxide, to the extractive solution can minimize these unwanted effects. The aim of this work was to study the influence of the addition of colloidal silicon dioxide on enhancement of the performance of the drying of hydroalcoholic extract of Bauhinia forficata Link on a spouted bed of inert particles. The physical properties of the herbal extract and of its mixture with colloidal silicon dioxide at several concentrations (20% to 80% related to solids content) were quantified by determination of the surface tension, rheological properties, density, pH, and contact angles with the inert surfaces. Drying performance was evaluated through determination of the elutriation ratio, product recovery ratio, and product accumulation. The product was characterized through determination of the thermal degradation of bioactive compounds and product moisture content. The results indicated that the rheological properties of the extracts and their preparations...

## Parâmetros de produção e caracterização de produto seco de maytenus ilicifolia Martius ex Reissek - celastraceae - em torre de secagem por aspersão; Process parameters and characterization of Maytenus ilicifolia Martius ex Reissek – Celastraceae spray dried products

Oliveira, Olivia Werner
Tipo: Dissertação Formato: application/pdf
POR
Relevância na Pesquisa
48.111143%

## Filmes de SiO2 depositados e crescidos termicamente sobre SiC : caracterização físico-química e elétrica; SiO2 films deposited and thermally grown on SiC: Electrical and physicochemical characterization

Pitthan Filho, Eduardo
Tipo: Dissertação Formato: application/pdf
POR
Relevância na Pesquisa
48.224287%

## Influência da utilização de nanopartículas de dióxido de silício ou polissiloxano acrilado nas propriedades físicas de materiais resinosos = : Influence of silicon dioxide or acrylated polisiloxane on resin-based materials physical properties; Influence of silicon dioxide or acrylated polisiloxane on resin-based materials physical properties

Cristiane Rumi Fujiwara Yanikian
Fonte: Biblioteca Digital da Unicamp Publicador: Biblioteca Digital da Unicamp
Tipo: Dissertação de Mestrado Formato: application/pdf
Relevância na Pesquisa
47.88892%

## THE ROLE OF COLLOIDAL SILICON DIOXIDE IN THE ENHANCEMENT OF THE DRYING OF HERBAL PREPARATIONS IN SUSPENDED STATE

SOUZA, C. R. F.; DONIDA, M. W.; ROCHA, S. C. S.; OLIVEIRA, W. P.
Fonte: TAYLOR & FRANCIS INC Publicador: TAYLOR & FRANCIS INC
Tipo: Artigo de Revista Científica
ENG
Relevância na Pesquisa
68.261685%
Recently, some research groups have been developing studies aiming to apply spouted beds of inert particles for production of dried herbal extracts. However, mainly due to their complex composition, several problems arise during the spouted bed drying of herbal extracts such as bed instability, product accumulation, particle agglomeration, and bed collapse. The addition of drying carriers, like colloidal silicon dioxide, to the extractive solution can minimize these unwanted effects. The aim of this work was to study the influence of the addition of colloidal silicon dioxide on enhancement of the performance of the drying of hydroalcoholic extract of Bauhinia forficata Link on a spouted bed of inert particles. The physical properties of the herbal extract and of its mixture with colloidal silicon dioxide at several concentrations (20% to 80% related to solids content) were quantified by determination of the surface tension, rheological properties, density, pH, and contact angles with the inert surfaces. Drying performance was evaluated through determination of the elutriation ratio, product recovery ratio, and product accumulation. The product was characterized through determination of the thermal degradation of bioactive compounds and product moisture content. The results indicated that the rheological properties of the extracts and their preparations...

## Electroosmotic flow in vapor deposited silicon dioxide and nitride microchannels

Hamblin, Mark N.; Edwards, John M.; Lee, Milton L.; Woolley, Adam T.; Hawkins, Aaron R.
Fonte: American Institute of Physics Publicador: American Institute of Physics
Tipo: Artigo de Revista Científica
Relevância na Pesquisa
48.07283%
Electroosmotic flow was studied in thin film microchannels with silicon dioxide and silicon nitride sidewalls formed using plasma-enhanced chemical vapor deposition (PECVD). A sacrificial etching process was employed for channel fabrication allowing for cross-sections with heights of 3 μm, ranging from 2 μm to 50 μm in width. Flow rates were measured for single channels and multichannel electroosmotic pump structures for pH levels ranging from 2.6 to 8.3, and zeta potentials were calculated for both silicon dioxide and silicon nitride surfaces. Flow rates as high as 0.086 μL∕min were measured for nitride multichannel pumps at applied electric fields of 300 V∕mm. The surface characteristics of PECVD nitride were analyzed and compared to more well-known oxide surfaces to determine the density of amine sites compared to silanol sites.

## Preparation and characterization of Pluronic-colloidal silicon dioxide composite particles as liquid crystal precursor

Tipo: Artigo de Revista Científica
Relevância na Pesquisa
47.88892%
The purpose of this study was to produce spray-dried Pluronic-colloidal silicon dioxide (Aerosil) composite particles as a liquid crystal precursor that would form a liquid crystalline phase upon hydration. A Pluronic-colloidal silicon dioxide dispersion in isopropyl alcohol was spray-dried to obtain composite particles using different concentrations of Aerosil. Polarizing microscopy, gelation, gel melting, and rheological studies were employed to characterize the composite particles. The composite particles obtained were irregular, with concave depression. Gelation was found to decrease with the addition of Aerosil, while gel melting was found to increase with the concentration of Aerosil. Rheological studies showed an increase in elasticity as well as viscosity with an increase in the concentration of Aerosil. Composite particles showed improved gelation and rheological properties. These composite particles and the process by which they were obtained may be useful for designing various drug delivery systems.

## Nanocolumnar Preferentially Oriented PSZT Thin Films Deposited on Thermally Grown Silicon Dioxide

Sriram, S; Bhaskaran, M; Mitchell, A; Mitchell, DRG; Kostovski, G
Tipo: Artigo de Revista Científica
Relevância na Pesquisa
47.88892%
We report the first instance of deposition of preferentially oriented, nanocrystalline, and nanocolumnar strontium-doped lead zirconate titanate (PSZT) ferroelectric thin films directly on thermal silicon dioxide. No intermediate seed or activation layers were used between PSZT and silicon dioxide. The deposited thin films have been characterised using a combination of diffraction and microscopy techniques.

## Treatment of human astrocytoma U87 cells with silicon dioxide nanoparticles lowers their survival and alters their expression of mitochondrial and cell signaling proteins

Lai, James CK; Ananthakrishnan, Gayathri; Jandhyam, Sirisha; Dukhande, Vikas V; Bhushan, Alok; Gokhale, Mugdha; Daniels, Christopher K; Leung, Solomon W
Fonte: Dove Medical Press Publicador: Dove Medical Press
Tipo: Artigo de Revista Científica
EN
Relevância na Pesquisa
48.516943%
Recent evidence suggests silicon dioxide micro- and nanoparticles induce cytotoxic effects on lung cells. Thus, there is an increasing concern regarding their potential health hazard. Nevertheless, the putative toxicity of nanoparticles in mammalian cells has not yet been systematically investigated. We previously noted that several metallic oxide nanoparticles exert differential cytotoxic effects on human neural and nonneural cells. Therefore, we hypothesized that silicon dioxide nanoparticles induce cytotoxicity in U87 cells by lowering their survival by decreasing cell survival signaling and disturbing mitochondrial function. To investigate this hypothesis, we determined the activities of the key mitochondrial enzymes, citrate synthase and malate dehydrogenase, in astrocytoma U87 cells treated with silicon dioxide nanoparticles. In addition, we studied the expression of the mitochondrial DNA-encoded proteins, cytochrome C oxidase II and nicotinamide adenine dinucleotide (NADPH) dehydrogenase subunit 6, and cell signaling pathway protein extracellular signal-regulated kinase (ERK) and phosphorylated ERK in treated U87 cells. The activated form of ERK controls cell growth, differentiation, and proliferation. In parallel, we determined survival of U87 cells after treating them with various concentrations of silicon dioxide nanoparticles. Our results indicated that treatment with silicon dioxide nanoparticles induced decreases in U87 cell survival in a dose-related manner. The activities of citrate synthase and malate dehydrogenase in treated U87 cells were increased...

## Raman Spectra of High-κ Dielectric Layers Investigated with Micro-Raman Spectroscopy Comparison with Silicon Dioxide

Borowicz, P.; Taube, A.; Rzodkiewicz, W.; Latek, M.; Gierałtowska, S.
Fonte: Hindawi Publishing Corporation Publicador: Hindawi Publishing Corporation
Tipo: Artigo de Revista Científica
Relevância na Pesquisa
48.38762%
Three samples with dielectric layers from high-κ dielectrics, hafnium oxide, gadolinium-silicon oxide, and lanthanum-lutetium oxide on silicon substrate were studied by Raman spectroscopy. The results obtained for high-κ dielectrics were compared with spectra recorded for silicon dioxide. Raman spectra suggest the similarity of gadolinium-silicon oxide and lanthanum-lutetium oxide to the bulk nondensified silicon dioxide. The temperature treatment of hafnium oxide shows the evolution of the structure of this material. Raman spectra recorded for as-deposited hafnium oxide are similar to the results obtained for silicon dioxide layer. After thermal treatment especially at higher temperatures (600°C and above), the structure of hafnium oxide becomes similar to the bulk non-densified silicon dioxide.

## Growth and Etch Rate Study of Low Temperature Anodic Silicon Dioxide Thin Films

Ashok, Akarapu; Pal, Prem
Fonte: Hindawi Publishing Corporation Publicador: Hindawi Publishing Corporation
Tipo: Artigo de Revista Científica
Relevância na Pesquisa
48.279614%
Silicon dioxide (SiO2) thin films are most commonly used insulating films in the fabrication of silicon-based integrated circuits (ICs) and microelectromechanical systems (MEMS). Several techniques with different processing environments have been investigated to deposit silicon dioxide films at temperatures down to room temperature. Anodic oxidation of silicon is one of the low temperature processes to grow oxide films even below room temperature. In the present work, uniform silicon dioxide thin films are grown at room temperature by using anodic oxidation technique. Oxide films are synthesized in potentiostatic and potentiodynamic regimes at large applied voltages in order to investigate the effect of voltage, mechanical stirring of electrolyte, current density and the water percentage on growth rate, and the different properties of as-grown oxide films. Ellipsometry, FTIR, and SEM are employed to investigate various properties of the oxide films. A 5.25 Å/V growth rate is achieved in potentiostatic mode. In the case of potentiodynamic mode, 160 nm thickness is attained at 300 V. The oxide films developed in both modes are slightly silicon rich, uniform, and less porous. The present study is intended to inspect various properties which are considered for applications in MEMS and Microelectronics.

## pH-responsive drug delivery system based on hollow silicon dioxide micropillars coated with polyelectrolyte multilayers

Alba, María; Formentín, Pilar; Ferré-Borrull, Josep; Pallarès, Josep; Marsal, Lluís F
Tipo: Artigo de Revista Científica
Relevância na Pesquisa
48.185415%
We report on the fabrication of polyelectrolyte multilayer-coated hollow silicon dioxide micropillars as pH-responsive drug delivery systems. Silicon dioxide micropillars are based on macroporous silicon formed by electrochemical etching. Due to their hollow core capable of being loaded with chemically active agents, silicon dioxide micropillars provide additional function such as drug delivery system. The polyelectrolyte multilayer was assembled by the layer-by-layer technique based on the alternative deposition of cationic and anionic polyelectrolytes. The polyelectrolyte pair poly(allylamine hydrochloride) and sodium poly(styrene sulfonate) exhibited pH-responsive properties for the loading and release of a positively charged drug doxorubicin. The drug release rate was observed to be higher at pH 5.2 compared to that at pH 7.4. Furthermore, we assessed the effect of the number of polyelectrolyte bilayers on the drug release loading and release rate. Thus, this hybrid composite could be potentially applicable as a pH-controlled system for localized drug release.

## Optical properties of nanostructured silicon-rich silicon dioxide; Optical properties of nanostructured SRO

Stolfi, Michael Anthony
Fonte: Massachusetts Institute of Technology Publicador: Massachusetts Institute of Technology
Tipo: Tese de Doutorado Formato: 195 p.
ENG
Relevância na Pesquisa
48.04134%
We have conducted a study of the optical properties of sputtered silicon-rich silicon dioxide (SRO) thin films with specific application for the fabrication of erbium-doped waveguide amplifiers and lasers, polarization sensitive devices and devices to modify the polarization state of light. The SRO thin films were prepared through a reactive RF magnetron sputtering from a Si target in an O2/Ar gas mixture. The film stoichiometry was controlled by varying the power applied to the Si target or changing the percentage of 02 in the gas mixture. A deposition model is presented which incorporates the physical and chemical aspects of the sputtering process to predict the film stoichiometry and deposition rate for variable deposition conditions. The as-deposited films are optically anisotropic with a positive birefringence (nTM > nTE) that increases with increasing silicon content for as-deposited films. The dependence of the birefringence on annealing temperature is also influenced by the silicon content. After annealing, samples with high silicon content (>45 at%) showed birefringence enhancement while samples with low silicon content (<45 at%) showed birefringence reduction. A birefringence of more than 3% can be generated in films with high silicon content (50 at% Si) annealed at 11000C.; (cont.) We attribute the birefringence to the columnar film morphology achieved through our sputtering conditions. Er was incorporated through reactive co-sputtering from Er and Si targets in the same O2/Ar atmosphere in order to investigate the energy-transfer process between SRO and Er for low annealing temperatures. By studying the photoluminescence (PL) intensity of Er:SRO samples annealed in a wide range of temperatures...

## The Impact of Atomic Hydrogen on the Properties of the Silicon/Silicon Dioxide Interface

Zhang, Chun
Tipo: Thesis (PhD); Doctor of Philosophy (PhD)
EN_AU
Relevância na Pesquisa
57.88988%
In this thesis, the influence of atomic hydrogen on the surface passivation of Si and SiO2 interface was mainly investigated. The effect of corona charging, humidity, UV exposure and mineral acid on Si and SiO2 interface was compared to the effect of atomic hydrogen. The electrical properties of thin, low temperature oxides, and in particular the degree of surface passivation achievable with such oxides, was also investigated and compared with the properties of oxides grown at higher temperatures. Both wet and dry oxidations were used...Immersion of oxidised silicon samples in mineral acids resulted in a modification to the Si and SiO2 interface properties. It could also provide a very cheap, alternative means of surface passivation due to hydrogen or a hydrogen complex diffusing into the oxide layer and affecting the interface properties.; ANU Miscellaneous Scholarship.; Yes

## The mechanism of hydrophilic and hydrophobic colloidal silicon dioxide types as glidants; Mechanismus der Wirkung hydrophiler und hydrophober hochdisperser Kieselsäure als Fließregulierungsmittel

Jonat, Stéphane
Tipo: Dissertação
EN
Relevância na Pesquisa
67.88892%
AEROSIL® 200 is a hydrophilic highly disperse colloidal silicon dioxide (CSD) that is commonly used to improve flowability. This conventional CSD has low bulk and tapped densities and can produce dust if handled improperly. In order to improve its handling, special mechanical processes were developed for the homogeneous compaction of CSD. As a result, two new products have been recently introduced: AEROSIL® 200 VV and AEROSIL® R 972 V. AEROSIL® 200 VV is hydrophilic and chemically identical to AEROSIL® 200. It differs from conventional CSD only in its higher tapped density and its larger secondary agglomerates. AEROSIL® R 972 V is hydrophobic, a result of dimethyl silyl groups chemically bound to the silica surface. The aims of this study is to compare the compacted hydrophilic and hydrophobic products to their non-compacted hydrophilic counterparts in terms of their effect on flowability and tableting properties. Therefore, different CSD types were used in combination with the three filler/binders namely microcrystalline cellulose, Avicel® PH 101, pregelatinzed starch, Starch 1500® and lactose, Tablettose® 80. The investigations were carried out on a microscopic and macroscopic level to get a better understanding of the mechanism of glidant action. The first part of the study evaluates the flowability of the filler/binders upon addition of 0.5% CSD under different mixing conditions using angle of repose...

## Synthesis of nickel disilicide quantum dots in silicon dioxide films

Yoon, Jong-Hwan; Elliman, Robert
Tipo: Artigo de Revista Científica
Relevância na Pesquisa
58.23906%
Nickel disilicide (NiS2) quantum dots (QDs) have been grown in silicon-rich oxide (SiOx) films by either ion implanting with nickel or coating with an evaporated Ni film and annealing at 1100 °C. It is shown that both techniques produce well-defined sing

## Thermal Contact Resistance Across Nanoscale Silicon Dioxide and Silicon Interface

Chen, Jie; Zhang, Gang; Li, Baowen
Tipo: Artigo de Revista Científica
Relevância na Pesquisa
48.16703%
Silicon dioxide and silicon (SiO$_{2}$/Si) interface plays a very important role in semiconductor industry. However, at nanoscale, its interfacial thermal properties haven't been well understood so far. In this paper, we systematically study the interfacial thermal resistance (Kapitza resistance) of a heterojunction composed of amorphous silicon dioxide and crystalline silicon by using molecular dynamics simulations. Numerical results have shown that Kapitza resistance at SiO$_{2}$/Si interface depends on the interfacial coupling strength remarkably. In the weak interfacial coupling limit, Kapitza resistance depends on both the detailed interfacial structure and the length of the heterojunction, showing large fluctuation among different samples. In contrast, it is almost insensitive to the detailed interfacial structure or the length of the heterojunction in the strong interfacial coupling limit, giving rise to a nearly constant value around 0.9 $\times10^{-9}$ m$^{2}$KW$^{-1}$ at room temperature. Moreover, the temperature dependent Kapitza resistance in the strong interfacial coupling limit has also been examined. Our study provides useful guidance to the thermal management and heat dissipation across nanoscale SiO$_{2}$/Si interface...

## Anisotropic Vapor HF etching of silicon dioxide for Si microstructure release

Passi, Vikram; Sodervall, Ulf; Nilsson, Bengt; Petersson, Goran; Hagberg, Mats; Krzeminski, Christophe; Dubois, Emmanuel; Bois, Bert Du; Raskin, Jean-Pierre
Tipo: Artigo de Revista Científica
Relevância na Pesquisa
48.261685%
Damages are created in a sacrificial layer of silicon dioxide by ion implantation to enhance the etch rate of silicon-dioxide in liquid and vapor phase hydrofluoric acid. The etch rate ratio between implanted and unimplanted silicon dioxide is more than 150 in vapor hydrofluoric acid (VHF). This feature is of interest to greatly reduce the underetch of microelectromechanical systems anchors. Based on the experimentally extracted etch rate of unimplanted and implanted silicon dioxide, the patterning of the sacrificial layer can be predicted by simulation.

## Temperature-dependent transition to progressive breakdown in thin silicon dioxide based gate dielectrics

Suñé, Jordi,
Tipo: Artigo de Revista Científica Formato: application/pdf