Probabilistic modeling of the flows and environmental risks of nano-silica

International Nuclear Information System (INIS)

Wang, Yan; Kalinina, Anna; Sun, Tianyin; Nowack, Bernd

2016-01-01

Nano-silica, the engineered nanomaterial with one of the largest production volumes, has a wide range of applications in consumer products and industry. This study aimed to quantify the exposure of nano-silica to the environment and to assess its risk to surface waters. Concentrations were calculated for four environmental (air, soil, surface water, sediments) and two technical compartments (wastewater, solid waste) for the EU and Switzerland using probabilistic material flow modeling. The corresponding median concentration in surface water is predicted to be 0.12 μg/l in the EU (0.053–3.3 μg/l, 15/85% quantiles). The concentrations in sediments in the complete sedimentation scenario were found to be the largest among all environmental compartments, with a median annual increase of 0.43 mg/kg·y in the EU (0.19–12 mg/kg·y, 15/85% quantiles). Moreover, probabilistic species sensitivity distributions (PSSD) were computed and the risk of nano-silica in surface waters was quantified by comparing the predicted environmental concentration (PEC) with the predicted no-effect concentration (PNEC) distribution, which was derived from the cumulative PSSD. This assessment suggests that nano-silica currently poses no risk to aquatic organisms in surface waters. Further investigations are needed to assess the risk of nano-silica in other environmental compartments, which is currently not possible due to a lack of ecotoxicological data. - Highlights: • We quantify the exposure of nano-silica to technical systems and the environment. • The median concentration in surface waters is predicted to be 0.12 μg/L in the EU. • Probabilistic species sensitivity distributions were computed for surface waters. • The risk assessment suggests that nano-silica poses no risk to aquatic organisms.

Control the Morphologies and the Pore Architectures of Meso porous Silicas through a Dual-Templating Approach

International Nuclear Information System (INIS)

Wang, H.; Chen, H.; Xu, Z.; Wang, S.; Li, B.; Li, Y.

2012-01-01

Meso porous silica nanospheres were prepared using a chiral cationic low-molecular-weight amphiphile and organic solvents such as toluene, cyclohexane, and tetrachlorocarbon through a dual-templating approach. X-ray diffraction, nitrogen sorption, field emission scanning electron microscopy, and transmission electron microscopy techniques have been used to characterize the meso porous silicas. The volume ratio of toluene to water plays an important role in controlling the morphologies and the pore architectures of the meso porous silicas. It was also found that meso porous silica nano flakes can be prepared by adding tetrahydrofuran to the reaction mixtures.

Flow and granular analysis of cement paste with Nano-silica (nS): from macro to nano concrete design

NARCIS (Netherlands)

Quercia Bianchi, G.; Brouwers, H.J.H.; Hüsken, G.

2010-01-01

Current micro-silica is only applied in special cases, due to its high price, and nano-silica is not used in practice yet. The new nano-silica can be produced in such quantities and for low prices that mass application in concrete is within reach. It may replace cement in the mix, which is the most

Effects of nano-silica (NS) additions on durability of SCC mixtures

NARCIS (Netherlands)

Quercia Bianchi, G.; Spiesz, P.R.; Brouwers, H.J.H.; Andrade, C; Gulikers, JJW; Polder, R

2015-01-01

In this study, three different types of nano-silica were applied in self-compacting concrete (SCC), one produced by the controlled dissolution of the olivine mineral and two having similar particle size distributions (PSD), but produced through two different processes: fumed powder nano-silica and

Effects of nano-silica on mechanical performance and microstructure of ultra-high performance concrete

Energy Technology Data Exchange (ETDEWEB)

Mendes, T. M., E-mail: thiagomendes@utfpr.edu.br [Universidade Tecnologica Federal do Parana (UTFPR), Londrina, PR (Brazil). Departamento de Engenharia Ambiental; Repette, W.L., E-mail: wellington.repette@gmail.br [Universidade Federal de Santa Catarina (UFSC), Florianopolis, SC (Brazil). Dept. de Engenharia Civil; Reis, P.J., E-mail: pjlondrina@yahoo.com.br [Univeridade Estadual de Londrina (UEL), PR (Brazil). Lab. de Fisica Nuclear Aplicada

2017-07-15

The use of nanoparticles in ultra-high strength concretes can result in a positive effect on mechanical performance of these cementitious materials. This study evaluated mixtures containing 10 and 20 wt% of silica fume, for which the optimum nano-silica content was determined, i.e. the quantity of nano-silica that resulted on the higher gain of strength. The physical characterization of raw materials was done in terms of particle size distribution, density and specific surface area. Chemical and mineralogical compositions of materials were obtained through fluorescence and X-ray diffraction. The mechanical performance was evaluated by compressive strength, flexural strength and dynamic elastic modulus measurements. The microstructural analysis of mixtures containing nano-silica was performed by X-ray diffraction, thermogravimetry, mercury intrusion porosimetry and scanning electron microscopy. Obtained results indicate an optimum content of nano-silica of 0.62 wt%, considering compressive and flexural strengths. This performance improvement was directly related to two important microstructural aspects: the packing effect and pozzolanic reaction of nano-silica. (author)

Effects of nano-silica on mechanical performance and microstructure of ultra-high performance concrete

International Nuclear Information System (INIS)

Mendes, T. M.; Repette, W.L.; Reis, P.J.

2017-01-01

The use of nanoparticles in ultra-high strength concretes can result in a positive effect on mechanical performance of these cementitious materials. This study evaluated mixtures containing 10 and 20 wt% of silica fume, for which the optimum nano-silica content was determined, i.e. the quantity of nano-silica that resulted on the higher gain of strength. The physical characterization of raw materials was done in terms of particle size distribution, density and specific surface area. Chemical and mineralogical compositions of materials were obtained through fluorescence and X-ray diffraction. The mechanical performance was evaluated by compressive strength, flexural strength and dynamic elastic modulus measurements. The microstructural analysis of mixtures containing nano-silica was performed by X-ray diffraction, thermogravimetry, mercury intrusion porosimetry and scanning electron microscopy. Obtained results indicate an optimum content of nano-silica of 0.62 wt%, considering compressive and flexural strengths. This performance improvement was directly related to two important microstructural aspects: the packing effect and pozzolanic reaction of nano-silica. (author)

Nano-silica as the go material on heat resistant tunnel lining

Science.gov (United States)

Omar, Faizah; Osman, S. A.; Mutalib, A.

2018-04-01

This paper is concerned with passive fire protection method of protective concrete mix that is made up of fly ash, polypropylene fibre, and nano-silica. Nano-silica is focused on as the innovative material to be used in the composition of the protective concrete mix. The previous experimental studies which analyse the performance of passive fire protection on tunnels are discussed. This paper also discusses passive fire protection. The fire protection materials and behaviour analyses of tunnel structure are also presented. At the end of the paper, the recommendation of the optimum composition concrete material with fly ash, polypropylene fibre and nano-silica as tunnel lining fire protective materials is proposed.

Probabilistic modeling of the flows and environmental risks of nano-silica.

Science.gov (United States)

Wang, Yan; Kalinina, Anna; Sun, Tianyin; Nowack, Bernd

2016-03-01

Nano-silica, the engineered nanomaterial with one of the largest production volumes, has a wide range of applications in consumer products and industry. This study aimed to quantify the exposure of nano-silica to the environment and to assess its risk to surface waters. Concentrations were calculated for four environmental (air, soil, surface water, sediments) and two technical compartments (wastewater, solid waste) for the EU and Switzerland using probabilistic material flow modeling. The corresponding median concentration in surface water is predicted to be 0.12 μg/l in the EU (0.053-3.3 μg/l, 15/85% quantiles). The concentrations in sediments in the complete sedimentation scenario were found to be the largest among all environmental compartments, with a median annual increase of 0.43 mg/kg · y in the EU (0.19-12 mg/kg · y, 15/85% quantiles). Moreover, probabilistic species sensitivity distributions (PSSD) were computed and the risk of nano-silica in surface waters was quantified by comparing the predicted environmental concentration (PEC) with the predicted no-effect concentration (PNEC) distribution, which was derived from the cumulative PSSD. This assessment suggests that nano-silica currently poses no risk to aquatic organisms in surface waters. Further investigations are needed to assess the risk of nano-silica in other environmental compartments, which is currently not possible due to a lack of ecotoxicological data. Copyright © 2015 Elsevier B.V. All rights reserved.

Properties of Fiber-Reinforced Mortars Incorporating Nano-Silica

Directory of Open Access Journals (Sweden)

Ahmed Ghazy

2016-02-01

Full Text Available Repair and rehabilitation of deteriorating concrete elements are of significant concern in many infrastructural facilities and remain a challenging task. Concerted research efforts are needed to develop repair materials that are sustainable, durable, and cost-effective. Research data show that fiber-reinforced mortars/concretes have superior performance in terms of volume stability and toughness. In addition, it has been recently reported that nano-silica particles can generally improve the mechanical and durability properties of cement-based systems. Thus, there has been a growing interest in the use of nano-modified fiber-reinforced cementitious composites/mortars (NFRM in repair and rehabilitation applications of concrete structures. The current study investigates various mechanical and durability properties of nano-modified mortar containing different types of fibers (steel, basalt, and hybrid (basalt and polypropylene, in terms of compressive and flexural strengths, toughness, drying shrinkage, penetrability, and resistance to salt-frost scaling. The results highlight the overall effectiveness of the NFRM owing to the synergistic effects of nano-silica and fibers.

Densification of Silica Spheres: A New Pathway to Nano-Dimensioned Zeolite-Based Catalysts.

Science.gov (United States)

Machoke, Albert Gonche Fortunatus; Apeleo Zubiri, Benjamin; Leonhardt, Rainer; Marthala, Venkata Ramana Reddy; Schmiele, Martin; Unruh, Tobias; Hartmann, Martin; Spiecker, Erdman; Schwieger, Wilhelm

2017-08-16

Nanosized materials are expected to play a unique role in the development of future catalytic processes. Herein, pre-prepared and geometrically well-defined amorphous silica spheres are densified into silica-rich zeolites with nanosized dimensions. After the densification, the obtained nanosized zeolites exhibit the same spherical morphology like the starting precursor but characterized by a drastically reduced size, higher density, and high crystallinity. The phase transformation into crystalline zeolite material and the densification effect are achieved through a well-controlled steam-assisted treatment of the larger precursor particles so that the transformation process proceeds always towards the center of the spheres, just like a shrinking process. Furthermore, this procedure is applicable also to commercially available silica particles, as well as aluminum-containing systems (precursors) leading to acidic nano-catalysts with improved catalytic performance. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Straightforward fabrication of black nano silica dusting powder for latent fingerprint imaging

Science.gov (United States)

Komalasari, Isna; Krismastuti, Fransiska Sri Herwahyu; Elishian, Christine; Handayani, Eka Mardika; Nugraha, Willy Cahya; Ketrin, Rosi

2017-11-01

Imaging of latent fingerprint pattern (aka fingermark) is one of the most important and accurate detection methods in forensic investigation because of the characteristic of individual fingerprint. This detection technique relies on the mechanical adherence of fingerprint powder to the moisture and oily component of the skin left on the surface. The particle size of fingerprint powder is one of the critical parameter to obtain excellent fingerprint image. This study develops a simple, cheap and straightforward method to fabricate Nano size black dusting fingerprint powder based on Nano silica and applies the powder to visualize latent fingerprint. The nanostructured silica was prepared from tetraethoxysilane (TEOS) and then modified with Nano carbon, methylene blue and sodium acetate to color the powder. Finally, as a proof-of-principle, the ability of this black Nano silica dusting powder to image latent fingerprint is successfully demonstrated and the results show that this fingerprint powder provides clearer fingerprint pattern compared to the commercial one highlighting the potential application of the nanostructured silica in forensic science.

Development of construction materials using nano-silica and aggregates recycled from construction and demolition waste.

Science.gov (United States)

Mukharjee, Bibhuti Bhusan; Barai, Sudhirkumar V

2015-06-01

The present work addresses the development of novel construction materials utilising commercial grade nano-silica and recycled aggregates retrieved from construction and demolition waste. For this, experimental work has been carried out to examine the influence of nano-silica and recycled aggregates on compressive strength, modulus of elasticity, water absorption, density and volume of voids of concrete. Fully natural and recycled aggregate concrete mixes are designed by replacing cement with three levels (0.75%, 1.5% and 3%) of nano-silica. The results of the present investigation depict that improvement in early days compressive strength is achieved with the incorporation of nano-silica in addition to the restoration of reduction in compressive strength of recycled aggregate concrete mixes caused owing to the replacement of natural aggregates by recycled aggregates. Moreover, the increase in water absorption and volume of voids with a reduction of bulk density was detected with the incorporation of recycled aggregates in place of natural aggregates. However, enhancement in density and reduction in water absorption and volume of voids of recycled aggregate concrete resulted from the addition of nano-silica. In addition, the results of the study reveal that nano-silica has no significant effect on elastic modulus of concrete. © The Author(s) 2015.

[Response surface method optimize of nano-silica solid dispersion technology assistant enzymatic hydrolysis preparation genistein].

Science.gov (United States)

Jin, Xin; Zhang, Zhen-Hai; Zhu, Jing; Sun, E; Yu, Dan-Hong; Chen, Xiao-Yun; Liu, Qi-Yuan; Ning, Qing; Jia, Xiao-Bin

2012-04-01

This article reports that nano-silica solid dispersion technology was used to raise genistein efficiency through increasing the enzymatic hydrolysis rate. Firstly, genistin-nano-silica solid dispersion was prepared by solvent method. And differential scanning calorimetry (DSC) and transmission electron microscopy (TEM) were used to verify the formation of solid dispersion, then enzymatic hydrolysis of solid dispersion was done by snailase to get genistein. With the conversion of genistein as criteria, single factor experiments were used to study the different factors affecting enzymatic hydrolysis of genistin and its solid dispersion. And then, response surface method was used to optimize of nano-silica solid dispersion technology assistant enzymatic hydrolysis. The optimum condition to get genistein through enzymatic hydrolysis of genistin-nano-silica solid dispersion was pH 7.1, temperature 52.2 degrees C, enzyme concentration 5.0 mg x mL(-1) and reaction time 7 h. Under this condition, the conversion of genistein was (93.47 +/- 2.40)%. Comparing with that without forming the genistin-nano-silica solid dispersion, the conversion increased 2.62 fold. At the same time, the product of hydrolysis was purified to get pure genistein. The method of enzymatic hydrolysis of genistin-nano-silica solid dispersion by snailase to obtain genistein is simple, efficiency and suitable for the modern scale production.

Antimicrobial activity of silica coated silicon nano-tubes (SCSNT) and silica coated silicon nano-particles (SCSNP) synthesized by gas phase condensation.

Science.gov (United States)

Tank, Chiti; Raman, Sujatha; Karan, Sujoy; Gosavi, Suresh; Lalla, Niranjan P; Sathe, Vasant; Berndt, Richard; Gade, W N; Bhoraskar, S V; Mathe, Vikas L

2013-06-01

Silica-coated, silicon nanotubes (SCSNTs) and silica-coated, silicon nanoparticles (SCSNPs) have been synthesized by catalyst-free single-step gas phase condensation using the arc plasma process. Transmission electron microscopy and scanning tunneling microscopy showed that SCSNTs exhibited a wall thickness of less than 1 nm, with an average diameter of 14 nm and a length of several 100 nm. Both nano-structures had a high specific surface area. The present study has demonstrated cheaper, resistance-free and effective antibacterial activity in silica-coated silicon nano-structures, each for two Gram-positive and Gram-negative bacteria. The minimum inhibitory concentration (MIC) was estimated, using the optical densitometric technique, and by determining colony-forming units. The MIC was found to range in the order of micrograms, which is comparable to the reported MIC of metal oxides for these bacteria. SCSNTs were found to be more effective in limiting the growth of multidrug-resistant Staphylococcus aureus over SCSNPs at 10 μg/ml (IC 50 = 100 μg/ml).

Investigating the properties and interaction mechanism of nano-silica in polyvinyl alcohol/polyacrylamide blends at an atomic level.

Science.gov (United States)

Wei, Qinghua; Wang, Yanen; Wang, Shuzhi; Zhang, Yingfeng; Chen, Xiongbiao

2017-11-01

The nano-silica can be incorporated into polymers for improved mechanical properties. Notably, the interaction between nano-silica and polymer is of a microscopic phenomenon and thus, hard to observe and study by using experimental methods. Based on molecular dynamics, this paper presents a study on the properties and the interaction mechanism of nano-silica in the polyvinyl alcohol (PVA)/polyacrylamide (PAM) blends at an atomic level. Specifically, six blends of PVA/PAM with varying concentrations of nano-silica (0-13wt%) and two interfacial interaction models of polymers on the silica surface were designed and analyzed at an atomic level in terms of concentration profile, mechanical properties, fractional free volume (FFV), dynamic properties of polymers and X-ray diffraction patterns. The concentration profile results and micromorphologies of equilibrium models suggest PAM molecular chains are easier to be adsorbed on the silica surface than PVA molecular chains in blends. The incorporation of nano-silica into the PVA/PAM blends can increase the blend mechanical properties, densities, and semicrystalline character. Meanwhile, the FFV and the mobility of polymer chain decrease with the silica concentration, which agrees with the results of mechanical properties, densities, and semicrystalline character. Our results also illustrate that an analysis of binding energies and pair correlation functions (PCF) allows for the discovery of the interaction mechanism of nano-silica in PVA/PAM blends; and that hydrogen bond interactions between polar functional groups of polymer molecular chains and the hydroxyl groups of the silica surface are involved in adsorption of the polymers on the silica surface, thus affecting the interaction mechanism of nano-silica in PVA/PAM blend systems. Copyright © 2017 Elsevier Ltd. All rights reserved.

Influence of colloidal nano-silica on alkyd autoxidation

DEFF Research Database (Denmark)

Nikolic, Miroslav; Sanadi, Anand Ramesh; Löf, David

2017-01-01

Nanoparticles are often added to coatings in order to improve their mechanical properties. However, nanoparticles can also influence the cross-linking reaction of polymers and overall curing kinetics, and from this follows that properties of interest are further impacted. In research studies...... on alkyd-based coatings, only the physical drying stage during the first 24 h has been studied in this respect until now. In this study, it was shown with the use of Raman spectroscopy that colloidal nano-silica can change the rate of alkyd autoxidation and how this effect is reflected on the tensile...... properties of the coating. One of the consequences of the influence of nano-silica on curing kinetics is that, contrary to implicit assumptions of common testing methods, the real effect of nanoparticles on mechanical properties can emerge much later in the coating lifetime....

Tribological properties of silica-graphene nano platelet composites

Czech Academy of Sciences Publication Activity Database

Porwal, H.; Tatarko, P.; Saggar, Richa; Grasso, S.; Mani, M.K.; Dlouhý, Ivo; Dusza, J.; Reece, M.J.

2014-01-01

Roč. 40, č. 8 (2014), s. 12067-12074 ISSN 0272-8842 EU Projects: European Commission(XE) 264526 - GLACERCO Institutional support: RVO:68081723 Keywords : wear resistance * friction coefficient * graphene nano-platelets * silica * SPS Subject RIV: JG - Metallurgy Impact factor: 2.605, year: 2014

Properties of nano-silica modified pervious concrete

Directory of Open Access Journals (Sweden)

Bashar S. Mohammed

2018-06-01

Full Text Available The aim of this study is to evaluate the effects of inclusion nano-silica (also known as nano-SiO2 on the properties of pervious concrete containing fly ash (FA as a partial replacement to cement. It has been found, for cementitious paste, that incorporating NS leads to reduce the cumulative pore volume by 13.4%. While the compressive strength of NS modified pervious concrete has been improved without adversely affecting its void ratio and permeability. The workability has been adversely affected by the inclusion of NS, which can be enhanced by incorporating the fly ash and superplasticizer. The porosity of cementitious paste has increased as the FA content is increased. These results are in good agreement with SEM results. For the pervious concrete voids ratio, permeability and infiltration rate were decreased against the increase of paste to the aggregate ratio Response surface methodology (RSM has also been used to develop a model for navigating the design space of NS modified pervious concrete. Models revealed 95% significance of confidence level with difference less than 0.2 between Pred R-Squared value of 0.9515 and Adj R-Squared. The general expression has been developed for all the responses with the different coefficients using the RSM. Keywords: Fly ash, Final setting time, Infiltration rate, Pervious concrete, Nano-silica

A new nanocomposite polymer electrolyte based on poly(vinyl alcohol) incorporating hypergrafted nano-silica

KAUST Repository

Hu, Xian-Lei

2012-01-01

Solid-state nanocomposite polymer electrolytes based on poly(vinyl alcohol)(PVA) incorporating hyperbranched poly(amine-ester) (HBPAE) grafted nano-silica (denoted as SiO2-g-HBPAE) have been prepared and investigated. Through surface pretreatment of nanoparticles, followed by Michael-addition and a self-condensation process, hyperbranched poly(amine-ester) was directly polymerized from the surface of nano-silica. Then the hypergrafted nanoparticles were added to PVA matrix, and blended with lithium perchlorate via mold casting method to fabricate nanocomposite polymer electrolytes. By introducing hypergrafted nanoparticles, ionic conductivity of solid composite is improved significantly at the testing temperature. Hypergrafted nano-silica may act as solid plasticizer, promoting lithium salt dissociation in the matrix as well as improving segmental motion of matrix. In addition, tensile testing shows that such materials are soft and tough even at room temperature. From the dielectric spectra of nanocomposite polymer electrolyte as the function of temperature, it can be deduced that Arrhenius behavior appears depending on the content of hypergrafted nano-silica and concentration of lithium perchlorate. At a loading of 15 wt% hypergrafted nano-silica and 54 wt% lithium perchlorate, promising ionic conductivities of PVA nanocomposite polymer electrolyte are achieved, about 1.51 × 10 ^-4 S cm^-1 at 25 °C and 1.36 × 10^-3 S cm^-1 at 100 °C. © The Royal Society of Chemistry.

Polypropylene Nano composites Obtained by In Situ Polymerization Using Metallocenes Catalyst: Influence of the Nanoparticles on the Final Polymer Morphology

International Nuclear Information System (INIS)

Zapata, P.; Quijada, R.

2012-01-01

Polypropylene nano composites containing silica nanospheres based on the sol-gel methods were produced via in situ polymerization using a rac-Et(Ind) 2 ZrCl 2 /methylaluminoxane (MAO) system. Two different routes were used depending on the interaction between the silica nanoparticles with the catalytic system. In route 1 the nanoparticles were added together with the catalytic system (rac-Et(Ind) 2 ZrCl 2 )/(MAO) directly into the reactor, and in route 2 the metallocenes rac-Et(Ind) 2 ZrCl 2 was supported on silica nanospheres pretreated with (MAO). SEM images show that when the nanospheres were added by both routes, they were replicated in the final polymer particle morphology; this phenomenon was more pronounced for PP obtained by route 2. The polypropylene (PP) nano composites obtained by both routes had a slightly higher percent crystallinity and crystallinity temperatures than pure PP. Transmission electron microscopy (TEM) images show that the nanospheres were well dispersed into the polypropylene matrix, particularly in the nano composites obtained by the support system (route 2).

Behaviour of Nano Silica in Tension Zone of High Performance Concrete Beams

Science.gov (United States)

Jaishankar, P.; Vivek, D.

2017-07-01

High performance concrete (HPC) is similar to High strength concrete (HSC).It is because of lowering of water to cement ratio, which is needed to attain high strength and generally improves other properties. This concrete contains one or more cementitious materials such as fly ash, Silica fume or ground granulated blast furnace slag and usually a super plasticizer. The term ‘high performance’ is somewhat different because the essential feature of this concrete is that it’s ingredients and proportions are specifically chosen so as to have particularly appropriate properties for the expected use of the structure such as high strength and low permeability. Usage of nano scale properties such as Nano SiO2 can result in dramatically improved properties from conventional grain size materials of same chemical composition. This project is more interested in evaluate the behaviour of nano silica in concrete for 5%, 10%, and 15% volume fraction of cement. Flexural test for beams were conducted with two point loads, at different percentage as mentioned above. From results interpolated, Nano silica with higher order replacement gives optimized results compared to control specimens.

Influence of Silane modified nano silica on the corrosion protection of zinc rich coating

International Nuclear Information System (INIS)

Nguyen Thuy Duong; To Thi Xuan Hang; Trinh Anh Truc; Pham Gia Vu; Bui Van Truoc; Thai Hoang

2015-01-01

Zinc rich coatings are the best effective primers for corrosion protection of carbon steel in aggressive conditions. For traditional zinc rich primer the zinc content is very high, more than 90 wt.%. The coating adhesion is decreased with the increase of zinc content, so that it is necessary to decrease the zinc content by using additives. In this study the nano silica modified by N-(2-Aminoethyl)-3-aminopropyltrimethoxysilane was prepared and incorporated in zinc rich epoxy coatings containing 85 wt.% zinc powder. The corrosion protection performance of coatings was evaluated by electrochemical impedance spectroscopy. The results obtained show that the presence of nano silica improved corrosion protection of zinc rich epoxy coating and the best protection was obtained with 3 wt.% nano silica. (author)

Influence of surface modified nano silica on alkyd binder before and after accelerated weathering

DEFF Research Database (Denmark)

Nikolic, Miroslav; Nguyen, Hiep Dinh; Daugaard, Anders Egede

2016-01-01

Introduction of nano fillers in exterior wood coatings is not straight forward. Influence on aging of polymer binder needs to be taken into account along with possible benefits that nano fillers can provide immediately after application. This study shows the influence of two differently modified...... hydrophobic nano silica on an alkyd binder for exterior wood coatings. One month after application, the highest strength and energy required to break the films was obtained with addition of 3% disilazane modified silica. Changes in tensile properties were accompanied with a small increase in glass transition...

Rapid Synthesis and Characterization of Nano sodalite Synthesized using Rice Husk Ash

International Nuclear Information System (INIS)

Siti Haslina Ahmad Rusmili; Zainab Ramli

2012-01-01

Rice husk ash (RHA) which contains more than 90 percent silica is proven to be an active silica source in zeolite synthesis. In this study, nano sodalite has been successfully synthesized hydrothermally at 60 degree Celsius using RHA as silica source in alkaline medium at various crystallization times. Commercial fumed silica was used as comparison for the silica source. Analysis by XRD has shown that pure nano sodalite was formed in 3 hours and stable up to more than 24 hours when using RHA as silica source. On the other hand, fumed silica produced pure nano sodalite only at 4 hours while a mixture of zeolites was observed outside this time range. FESEM shows a worm-like morphology of nano sodalite in the size range of 50-100 nm while FTIR shows the formation of aluminosilicates bonds. Analysis on the dissolved silica in the gel reaction mixture demonstrates the decreasing mass of silica after prolong time of crystallization which indicates the consumption of the dissolved silica in crystal growth of nano sodalite. This study shows that RHA is a better silica source in stabilizing the nano sodalite phase in oxide gel reaction mixture as compared to fumed silica. (author)

Effect of nano silica based modifying agent for hydrophobic coating application

International Nuclear Information System (INIS)

Nurul Huda Mudri; Nik Ghazali Nik Salleh; Mek Zah Salleh

2016-01-01

Hydrophobic coatings find wide application in industry due to their unique features such as water repellent and self-cleaning properties. In this study, modifying agent was synthesized by way of nano silica particles dispersion in polydimethyl siloxane with addition of surfactant, catalyst and stabilizer using high speed distemper. The modifying agent was added into coating formulation and cured under UV exposure. Scanning Electron Microscopy image of the film found that the nano silica particles were distributed well on substrate. Contact angle measurement gave the highest reading of 116 degree for 20 % wt of the modifying agent. The optical properties of the film were evaluated via transmission and haze test. (author)

Nano sized Particles of Silica and Its Derivatives for Applications in Various Branches of Food and Nutrition Sectors

International Nuclear Information System (INIS)

Kasaai, M. R.

2015-01-01

Nano sized particles of silica and its derivatives have been identified as versatile for a broad range of science, technology, and engineering applications. In this paper, an effort has been made to provide a short review from the available literature information on their applications in various branches of food and nutrition sectors. The information provided in this paper describes various parameters affecting their performances and efficiencies. The properties and applications of nano silica and its derivatives have been compared with micro silica and bulk-silica for their performances. The use of nano sized particles of silica and its derivatives provides a number of advantages. Their efficiencies and performances are significantly higher than those of the traditional ones

Silica/Perfluoropolymer nanocomposites fabricated by direct melt-compounding: a novel method without surface modification on nano-silica.

Science.gov (United States)

Tanahashi, Mitsuru; Hirose, Masaki; Watanabe, Yusuke; Lee, Jeong-Chang; Takeda, Kunihiko

2007-07-01

A novel method for the fabrication of silica/perfluoropolymer nanocomposites was investigated, whereby nano-sized silica particles without surface modification were dispersed uniformly through mechanical breakdown of loosely packed agglomerates of silica nanoparticles with low fracture strength in a polymer melt during direct melt-compounding. The method consists of two stages. The first stage involves preparation of the loose silica agglomerate, and the second stage involves melt-compounding of a completely hydrophobic perfluoropolymer, poly(tetrafluoroethyleneco-perfluoropropylvinylether), with the loose silica agglomerates prepared in the first stage. In the first stage, the packing structure and the fracture strength of the silica agglomerate were controlled by destabilizing an aqueous colloidal silica solution with a mean primary diameter of 190 nm via pH control and salt addition. In the next stage, the silica/perfluoropolymer nanocomposite was fabricated by breaking down the prepared loose silica agglomerates with low fracture strength by means of a shear force inside the polymer melt during melt-compounding.

Poly(2-aminothiazole)-silica nanocomposite particles: Synthesis and morphology control

Science.gov (United States)

Zou, Hua; Wu, Di; Sun, Hao; Chen, Suwu; Wang, Xia

2018-04-01

Synthesis of conducting polymer-silica colloidal nanocomposites has been recognized as an effective method to overcome the poor processability of heterocyclic conducting polymers prepared by chemical oxidative method. However, the morphology control of such conducting polymer-silica nanocomposites was seldomly reported in the literature. Novel poly(2-aminothiazole)(PAT)-silica nanocomposite particles can be conveniently prepared by chemical oxidative polymerization of 2-aminothiazole using CuCl2 oxidant in the presence of ∼20 nm silica nanoparticles. The effects of varying the oxidant/monomer ratio and silica sol concentration on the morphology and size of the resulting PAT-silica nanocmposites have been studied. Optimization of the oxidant/monomer molar ratio and initial silica sol concentration allows relatively round spherical particles of 150-350 nm in diameter to be achieved. The nanocomposite particles have a well-defined raspberry-like morphology with a silica-rich surface, but a significant fraction of PAT component still exists on the surface and, which is beneficial for its applications. Furthermore, the surface compositions of the colloidal nanocomposites could be regulated to some extent. Based on the above results, a possible formation mechanism of the spherical nanocomposite particles is proposed.

Stable Poly(methacrylic acid Brush Decorated Silica Nano-Particles by ARGET ATRP for Bioconjugation

Directory of Open Access Journals (Sweden)

Marcello Iacono

2015-08-01

Full Text Available The synthesis of polymer brush decorated silica nano-particles is demonstrated by activator regeneration by electron transfer atom transfer radical polymerization (ARGET ATRP grafting of poly(tert-butyl methacrylate. ATRP initiator decorated silica nano-particles were obtained using a novel trimethylsiloxane derivatised ATRP initiator obtained by click chemistry. Comparison of de-grafted polymers with polymer obtained from a sacrificial initiator demonstrated good agreement up to 55% monomer conversion. Subsequent mild deprotection of the tert-butyl ester groups using phosphoric acid yielded highly colloidal and pH stable hydrophilic nano-particles comprising approximately 50% methacrylic acid groups. The successful bio-conjugation was achieved by immobilization of Horseradish Peroxidase to the polymer brush decorated nano-particles and the enzyme activity demonstrated in a conversion of o-phenylene diamine dihydrochloride assay.

Hexadecane trapped in nano-pores of silica-aerogel

International Nuclear Information System (INIS)

Slavikova, B.; Jesenak, K.; Iskrova, M.; Majernik, V.; Sausa, O.; Kristiak, J.

2009-01-01

Ways of filling of the high-porous silica-aerogel with hydrocarbon C 16 H 34 and its efficient removal from the pores by physical method of the Positron Annihilation Spectroscopy were studied. As the most effective way to fill the SiO 2 aerogel appears through the implementation of a liquid phase, while the most appropriate way of removing of hexadecane is firing at an elevated temperature. Molecular system of hexadecane closed in nano-pores of silica-aerogel behaves otherwise than volume system of the same molecules. In the case of pure hexadecane phase transition was observed at 291 K, while solidification process is gradual with decrease of temperature in cetane trapped in pores of silica-aerogel. The results of the periods of life of o-Ps indicate greater turbidity in the pores of the molecular system compared to the volume sample of hexadecane.

Enhancement of impact strength of poly (methyl methacrylate) with surface fine-tuned nano-silica

International Nuclear Information System (INIS)

Wen, Bin; Dong, Yixiao; Wu, Lili; Long, Chao; Zhang, Chaocan

2015-01-01

Highly dispersible nanoparticles in organic solvent always receive wide interests due to their compatibility with polymer materials. This paper reported a kind of isopropanol alcohol silica dispersion which obtained using a method of azeotropic distillation. The isopropanol alcohol dispersed silica (IPADS) were treated with coupling agents to fine-tune their surface properties. Polymethyl methacrylate (PMMA) was then used as a research object to test the compatibility between IPADS and polymer. UV-vis spectra indicate that IPADS would reach its high compatibility with PMMA if coupling with trimethoxypropylsilane (PTMS). Followed experiments on PMMA proved that the high compatibility can prominently enhance the impact strength about 30%. The results may provide reference both for nano-silica modification and better understanding of nano-enhanced materials. (paper)

Enhancement of impact strength of poly (methyl methacrylate) with surface fine-tuned nano-silica

Science.gov (United States)

Wen, Bin; Dong, Yixiao; Wu, Lili; Long, Chao; Zhang, Chaocan

2015-07-01

Highly dispersible nanoparticles in organic solvent always receive wide interests due to their compatibility with polymer materials. This paper reported a kind of isopropanol alcohol silica dispersion which obtained using a method of azeotropic distillation. The isopropanol alcohol dispersed silica (IPADS) were treated with coupling agents to fine-tune their surface properties. Polymethyl methacrylate (PMMA) was then used as a research object to test the compatibility between IPADS and polymer. UV-vis spectra indicate that IPADS would reach its high compatibility with PMMA if coupling with trimethoxypropylsilane (PTMS). Followed experiments on PMMA proved that the high compatibility can prominently enhance the impact strength about 30%. The results may provide reference both for nano-silica modification and better understanding of nano-enhanced materials.

Characteristics of supported nano-TiO2/ZSM-5/silica gel (SNTZS): Photocatalytic degradation of phenol

International Nuclear Information System (INIS)

Zainudin, Nor Fauziah; Abdullah, Ahmad Zuhairi; Mohamed, Abdul Rahman

2010-01-01

Photocatalytic degradation of phenol was investigated using the supported nano-TiO 2 /ZSM-5/silica gel (SNTZS) as a photocatalyst in a batch reactor. The prepared photocatalyst was characterized using XRD, TEM, FT-IR and BET surface area analysis. The synthesized photocatalyst composition was developed using nano-TiO 2 as the photoactive component and zeolite (ZSM-5) as the adsorbents, all supported on silica gel using colloidal silica gel binder. The optimum formulation of SNTZS catalyst was observed to be (nano-TiO 2 :ZSM-5:silica gel:colloidal silica gel = 1:0.6:0.6:1) which giving about 90% degradation of 50 mg/L phenol solution in 180 min. The SNTZS exhibited higher photocatalytic activity than that of the commercial Degussa P25 which only gave 67% degradation. Its high photocatalytic activity was due to its large specific surface area (275.7 m 2 /g), small particle size (8.1 nm), high crystalline quality of the synthesized catalyst and low electron-hole pairs recombination rate as ZSM-5 adsorbent was used. The SNTZS photocatalyst synthesized in this study also has been proven to have an excellent adhesion and reusability.

Properties of Fiber-Reinforced Mortars Incorporating Nano-Silica

OpenAIRE

Ahmed Ghazy; Mohamed T. Bassuoni; Eugene Maguire; Mark O’Loan

2016-01-01

Repair and rehabilitation of deteriorating concrete elements are of significant concern in many infrastructural facilities and remain a challenging task. Concerted research efforts are needed to develop repair materials that are sustainable, durable, and cost-effective. Research data show that fiber-reinforced mortars/concretes have superior performance in terms of volume stability and toughness. In addition, it has been recently reported that nano-silica particles can generally improve the m...

Study some mechanical properties of self-compacting concrete with nano silica under severe saline environment conditions

Directory of Open Access Journals (Sweden)

Habeeb Ghalib

2018-01-01

Full Text Available The main aim of this research is to evaluate the performance of Nano silica self-compacting concrete which is subjected to severe saline conditions that contain sulfates and chlorides at concentrations similar to those existing in the soils and ground water of the middle and southern parts of Iraq. For this purpose, ordinary and sulfate resistant Portland cement without and with 3% Nano silica addition by weight of cementitious materials were used. Splitting tensile strength, flexural strength, static modulus of elasticity and ultrasonic pulse velocity were investigated for all exposure conditions and all types of mixes of self-compacting concrete at ages of 28, 60, 90, 120 and 180 days. Test results revealed that the inclusion of Nano Silica in concrete mixes improved clearly the mechanical properties of self-compacting concrete compared with reference concrete.

Effects of amorphous nano-silica additions on mechanical and durability performance of SCC mixtures

NARCIS (Netherlands)

Quercia Bianchi, G.; Spiesz, P.R.; Hüsken, G.; Brouwers, H.J.H.; Justnes, H.; Jacobsen, S.

2012-01-01

In the recent years the application of nanotechnology in building materials has increased exponentially. One of the most referred and used nano-materials is amorphous silica with particles size in the nano-range, even though its application and effect in concrete has not been fully understood yet.

Multifunctional nanomedicine with silica: Role of silica in nanoparticles for theranostic, imaging, and drug monitoring.

Science.gov (United States)

Chen, Fang; Hableel, Ghanim; Zhao, Eric Ruike; Jokerst, Jesse V

2018-07-01

The idea of multifunctional nanomedicine that enters the human body to diagnose and treat disease without major surgery is a long-standing dream of nanomaterials scientists. Nanomaterials show incredible properties that are not found in bulk materials, but achieving multi-functionality on a single material remains challenging. Integrating several types of materials at the nano-scale is critical to the success of multifunctional nanomedicine device. Here, we describe the advantages of silica nanoparticles as a tool for multifunctional nano-devices. Silica nanoparticles have been intensively studied in drug delivery due to their biocompatibility, degradability, tunable morphology, and ease of modification. Moreover, silica nanoparticles can be integrated with other materials to obtain more features and achieve theranostic capabilities and multimodality for imaging applications. In this review, we will first compare the properties of silica nanoparticles with other well-known nanomaterials for bio-applications and describe typical routes to synthesize and integrate silica nanoparticles. We will then highlight theranostic and multimodal imaging application that use silica-based nanoparticles with a particular interest in real-time monitoring of therapeutic molecules. Finally, we will present the challenges and perspective on future work with silica-based nanoparticles in medicine. Copyright © 2018 Elsevier Inc. All rights reserved.

Characteristics of supported nano-TiO{sub 2}/ZSM-5/silica gel (SNTZS): Photocatalytic degradation of phenol

Energy Technology Data Exchange (ETDEWEB)

Zainudin, Nor Fauziah; Abdullah, Ahmad Zuhairi [School of Chemical Engineering, Engineering Campus, Universiti Sains Malaysia, Seri Ampangan, 14300 Nibong Tebal, Penang (Malaysia); Mohamed, Abdul Rahman, E-mail: chrahman@eng.usm.my [School of Chemical Engineering, Engineering Campus, Universiti Sains Malaysia, Seri Ampangan, 14300 Nibong Tebal, Penang (Malaysia)

2010-02-15

Photocatalytic degradation of phenol was investigated using the supported nano-TiO{sub 2}/ZSM-5/silica gel (SNTZS) as a photocatalyst in a batch reactor. The prepared photocatalyst was characterized using XRD, TEM, FT-IR and BET surface area analysis. The synthesized photocatalyst composition was developed using nano-TiO{sub 2} as the photoactive component and zeolite (ZSM-5) as the adsorbents, all supported on silica gel using colloidal silica gel binder. The optimum formulation of SNTZS catalyst was observed to be (nano-TiO{sub 2}:ZSM-5:silica gel:colloidal silica gel = 1:0.6:0.6:1) which giving about 90% degradation of 50 mg/L phenol solution in 180 min. The SNTZS exhibited higher photocatalytic activity than that of the commercial Degussa P25 which only gave 67% degradation. Its high photocatalytic activity was due to its large specific surface area (275.7 m{sup 2}/g), small particle size (8.1 nm), high crystalline quality of the synthesized catalyst and low electron-hole pairs recombination rate as ZSM-5 adsorbent was used. The SNTZS photocatalyst synthesized in this study also has been proven to have an excellent adhesion and reusability.

Dispersion of nano-silica in monomer casting nylon6 and its effect on the structure and properties of composites

Directory of Open Access Journals (Sweden)

2010-07-01

Full Text Available To promote dispersion of nano-silica in monomer casting nylon6 (MC nylon6, nano-silica was dispersed in melted caprolactam with the assistance of ultrasound, anionic polymerization was then initiated to form silica/MC nylon6 in-situ nanocomposites. It was found that hydrogen bonds were formed between nano-silica and caprolactam, in the meantime, ultrasound helped to break the nanoparticles aggregations into smaller ones or even mono-dispersing particles. Therefore, the agglomerated nanoparticles were pulled apart and stabilized by caprolactam. Additionally, the rapid anionic polymerization of caprolactam also contributed to the avoidance of re-agglomeration and deposition of nanoparticles during the polymerization process, leading to the uniform distribution of nanoparticles in the polymer matrix. Mechanical tests indicated that the silica/MC nylon6 in-situ nanocomposites prepared according to the above strategy were simultaneously toughened, strengthened and stiffened. Thermogravimetric analysis (TGA results showed that thermal stability of nanocomposites was notably improved compared to neat MC nylon6.

Synthesis of nano grade hollow silica sphere via a soft template method.

Science.gov (United States)

Tsai, Ming-Shyong; Li, Miao Ju; Yen, Fu-Hsu

2008-06-01

The nano grade hollow silica sphere (HSS) was synthesized by a novel soft template method. We found that the precipitate of aluminate had a porous structure that could be the soft template for HSS. After mixing the colloidal silica with the aluminate precipitate, the bubble trapped in this porous structure could form the nano grade HSS. The aluminate precipitate was removed by adjusting the pH of the slurry to approximately 1. The outside diameter, the specific surface, and the mean pore size diameter of the forming HSS were 60-90 nm, 571 m2/g, and 3 nm, respectively. The formed HSS was collected by modifying the surface with Si(OCH3)3CHCH2 (VTMO) and then filtrating the precipitated gel in the n-butanol and ethanol solvent system.

A controlled release of ibuprofen by systematically tailoring the morphology of mesoporous silica materials

International Nuclear Information System (INIS)

Qu Fengyu; Zhu Guangshan; Lin Huiming; Zhang Weiwei; Sun Jinyu; Li Shougui; Qiu Shilun

2006-01-01

A series of mesoporous silica materials with similar pore sizes, different morphologies and variable pore geometries were prepared systematically. In order to control drug release, ibuprofen was employed as a model drug and the influence of morphology and pore geometry of mesoporous silica on drug release profiles was extensively studied. The mesoporous silica and drug-loaded samples were characterized by X-ray diffraction, Fourier transform IR spectroscopy, N 2 adsorption and desorption, scanning electron microscopy, and transmission electron microscopy. It was found that the drug-loading amount was directly correlated to the Brunauer-Emmett-Teller surface area, pore geometry, and pore volume; while the drug release profiles could be controlled by tailoring the morphologies of mesoporous silica carriers. - Graphical abstract: The release of ibuprofen is controlled by tailoring the morphologies of mesoporous silica. The mesoporous silica and drug-loaded samples are characterized by powder X-ray diffraction, Fourier transform IR spectroscopy, N 2 adsorption and desorption, scanning electron microscopy, and transmission electron microscopy. The drug-loading amount is directly correlated to the Brunauer-Emmett-Teller surface area, pore geometry, and pore volume; while the drug release profiles can be controlled by tailoring the morphologies of mesoporous silica carriers

Preparation and characterization of silk/silica hybrid biomaterials by sol-gel crosslinking process

Energy Technology Data Exchange (ETDEWEB)

Hou Aiqin, E-mail: aiqinhou@dhu.edu.c [National Engineering Research Center for Dyeing and Finishing of Textiles, Donghua University, 3H, 2999 North Renmin Road, Songjiang, Shanghai 201620 (China); Chen Huawei [National Engineering Research Center for Dyeing and Finishing of Textiles, Donghua University, 3H, 2999 North Renmin Road, Songjiang, Shanghai 201620 (China)

2010-03-15

The silk/silica hybrid biomaterials are synthesized by sol-gel crosslinking process. The chemical and morphological structures of silk/silica hybrids are investigated with micro-FT-IR spectra, X-ray diffraction, SEM, AFM, and DSC. The results show that the crosslinking reactions among inorganic nano-particles, fibroin and 2,4,6-tri[(2-epihydrin-3-bimethyl-ammonium)propyl]-1,3,5-triazine chloride (Tri-EBAC) take place during sol-gel process. The silk/silica hybrids form new molecular structures containing not only organic fibroin but also inorganic nano-silica particles. The inorganic particles are bounded to the fibroin through covalent bonds. The silk/silica hybrids can form excellent film with very even nanometer particles. The thermal properties of organic/inorganic hybrid are improved.

Preparation and characterization of silk/silica hybrid biomaterials by sol-gel crosslinking process

International Nuclear Information System (INIS)

Hou Aiqin; Chen Huawei

2010-01-01

The silk/silica hybrid biomaterials are synthesized by sol-gel crosslinking process. The chemical and morphological structures of silk/silica hybrids are investigated with micro-FT-IR spectra, X-ray diffraction, SEM, AFM, and DSC. The results show that the crosslinking reactions among inorganic nano-particles, fibroin and 2,4,6-tri[(2-epihydrin-3-bimethyl-ammonium)propyl]-1,3,5-triazine chloride (Tri-EBAC) take place during sol-gel process. The silk/silica hybrids form new molecular structures containing not only organic fibroin but also inorganic nano-silica particles. The inorganic particles are bounded to the fibroin through covalent bonds. The silk/silica hybrids can form excellent film with very even nanometer particles. The thermal properties of organic/inorganic hybrid are improved.

Preparation of EVA/silica nano composites characterized with solid state nuclear magnetic resonance; Obtencao de nanocomposito de EVA/SILICA e caracterizacao por ressonancia magnetica nuclear no estado solido

Energy Technology Data Exchange (ETDEWEB)

Passos, Adriano A; Tavares, Maria I.B.; Neto, Roberto C.P.; Moreira, Leonardo A; Ferreira, Antonio G., E-mail: mibt@ima.ufrj.br [Centro de Tecnologia, Instituto de Macromoleculas Professora Eloisa Mano, Universidade Federal do Rio de Janeiro, Rio de Janeiro, RJ (Brazil)

2011-07-01

Nano composites of poly(ethylene-co-vinyl acetate)/silica (SiO{sub 2}) with dimensions of ca. 40 nm were prepared via solution intercalation employing chloroform as a solvent. They were mainly characterized with nuclear magnetic resonance spectroscopy (NMR) employing carbon-13 (polymeric matrix), silicon-29 (nanoparticles) and through the determination of the proton spin-lattice relaxation time in the rotating frame (T{sub 1{rho}H}) (polymer matrix). From the NMR results it was inferred that up to 5% of silica in mass a well dispersed nano composite was obtained, owing to a strong interaction between silica and the EVA matrix. (author)

Abrasion Resistance of Nano Silica Modified Roller Compacted Rubbercrete: Cantabro Loss Method and Response Surface Methodology Approach

Science.gov (United States)

Adamu, Musa; Mohammed, Bashar S.; Shafiq, Nasir

2018-04-01

Roller compacted concrete (RCC) when used for pavement is subjected to skidding/rubbing by wheels of moving vehicles, this causes pavement surface to wear out and abrade. Therefore, abrasion resistance is one of the most important properties of concern for RCC pavement. In this study, response surface methodology was used to design, evaluate and analyze the effect of partial replacement of fine aggregate with crumb rubber, and addition of nano silica on the abrasion resistance of roller compacted rubbercrete (RCR). RCR is the terminology used for RCC pavement where crumb rubber was used as partial replacement to fine aggregate. The Box-Behnken design method was used to develop the mixtures combinations using 10%, 20%, and 30% crumb rubber with 0%, 1%, and 2% nano silica. The Cantabro loss method was used to measure the abrasion resistance. The results showed that the abrasion resistance of RCR decreases with increase in crumb rubber content, and increases with increase in addition of nano silica. The analysis of variance shows that the model developed using response surface methodology (RSM) has a very good degree of correlation, and can be used to predict the abrasion resistance of RCR with a percentage error of 5.44%. The combination of 10.76% crumb rubber and 1.59% nano silica yielded the best combinations of RCR in terms of abrasion resistance of RCR.

Nano-structured silica coated mesoporous carbon micro-granules for potential application in water filtration

Science.gov (United States)

Das, Avik; Sen, D.; Mazumder, S.; Ghosh, A. K.

2017-05-01

A novel nano-composite spherical micro-granule has been synthesized using a facile technique of solvent evaporation induced assembly of nanoparticles for potential application in water filtration. The spherical micro-granule is comprised of nano-structured shell of hydrophilic silica encapsulating a hydrophobic mesoporous carbon at the core. Hierarchical structure of such core-shell micro-granules has been rigorously characterized using small-angle neutron and X-ray scattering techniques and complemented with scanning electron microscopy. The hydrophilic silica envelope around the carbon core helps in incorporation of such granules into the hydrophilic polymeric ultra-filtration membrane. The interstitial micro-pores present in the silica shell can serve as water transport channels and the mesoporus carbon core enhances the separation performance due its well adsorption characteristics. It has been found that the incorporation of such granules inside the ultra-filtration membrane indeed enhances the water permeability as well as the separation performance in a significant way.

The effect of nano-silica fertilizer concentration and rice hull ash doses on soybean (Glycine max (L.) Merrill) growth and yield

Science.gov (United States)

Suciaty, T.; Purnomo, D.; Sakya, A. T.; Supriyadi

2018-03-01

Agriculture is facing a number of challenges included limited water supply, low nutrient use efficiency, etc affected by climate change. Nano-silica is a product of nanotechnology, the frontier technologies to enhance crop productivity under climate change threats. The purpose of the research was to investigate the effects of nano silica concentration and rice hull ash on growth and yield of soybean. The experiment was conducted at Gagasari village, Cirebon, West Java from March until June 2017. The treatments were arranged by using factorial completely randomized block design with two factors. The first factor was a concentration of nano silica fertilizer consisted of four levels i.e., 0, 1.75, 2.5, and 3.75 ml.l‑1. The second factor was doses of rice hull ash consisted of four levels i.e., 0, 1, 2, and 3 ton.ha‑1. Each treatment combinations was repeated three times. The result showed that concentration of nano silica individually affected the number of leaves and number of branches, NAR and RGR, productive branches at 21, 30-45, and 35 daps, respectively. It also affected the seed dry weight plant‑1 and plot‑1. Meanwhile, doses of rice hull ash affected LAI, NAR, and RGR, 15-30, and 30-45 dap, respectively. Dry seed weight plot‑1 was also affected by doses of rice hull ash. There was an interaction effect between nano-silica concentration and doses of rice hull ash on number pods.plant‑1. Combinations of 2.5 ml.l‑1 nano-silica and 3 ton.ha‑1 of rice hull ash gave the highest number pods.plant‑1.

Experimental study of the synthesis and characterisation of silica nanoparticles via the sol-gel method

International Nuclear Information System (INIS)

Tabatabaei, S; Shukohfar, A; Aghababazadeh, R; Mirhabibi, A

2006-01-01

Silica nano-particles were synthesised by chemical methods from tetraethylorthosilicate (TEOS), ethanol (C 2 H 5 OH) and deionized water in the presence of ammonia as catalyst at room temperature. The morphology and structure of colloidal silica particles formed depend on the molar ratio of reagents. The formation of silica particles has been investigated using different solvents: ethanol and ethanol-glycerol. The nature and morphology of particles was investigated by scanning electron microscopy (SEM), transmission electron microscopy (TEM), transmission electron microscopy (TEM) and X-ray diffraction (XRD)

A new nanocomposite polymer electrolyte based on poly(vinyl alcohol) incorporating hypergrafted nano-silica

KAUST Repository

Hu, Xian-Lei; Hou, Gao-Ming; Zhang, Ming-Qiu; Rong, Min-Zhi; Ruan, Wen-Hong; Giannelis, Emmanuel P.

2012-01-01

perchlorate via mold casting method to fabricate nanocomposite polymer electrolytes. By introducing hypergrafted nanoparticles, ionic conductivity of solid composite is improved significantly at the testing temperature. Hypergrafted nano-silica may act

The Effect of Using Sewage Sludge Ash with and without Nano Silica Particles on Properties of Self-compacting Cement Based Materials

Directory of Open Access Journals (Sweden)

Amin Khoshravesh

2014-10-01

Full Text Available Nowadays using pozzolanic materials is crucial as a replacement of needed cement, improving properties of cement based materials and saving costs. On the other hand sewage sludge is harmful to the environment and human health. So in this research the sewage sludge ash has been used as an artificial pozzolan to produce self compacting cement based materials which could be evaluated as a revolution in the concrete industry. The objective of this research was to accelerate the performance of sewage sludge ash by utilizing nano silica particles. This research includes 10 mix designs for self compacting mortar and concrete made up of binary and ternary cementitious blends of sewage sludge ash (0%,5%,10%,15%,20% and nano silica (0%,1%. The results showed that by adding the sewage sludge ash, rheological and mechanical properties of the samples were reduced and for small percentages of sewage sludge ash, the durability characteristics were improved. The results also showed that adding nano silica improved the mechanical and durability properties of self compacting mortar and concrete. Finally in presence of nano silica, the reactivity of the sewage sludge ash was increased and its performance was improved.

Melt flow and mechanical properties of silica/perfluoropolymer nanocomposites Fabricated by direct melt-compounding without surface modification on nano-silica.

Science.gov (United States)

Tanahashi, Mitsuru; Watanabe, Yusuke; Lee, Jeong-Chang; Takeda, Kunihiko; Fujisawa, Toshiharu

2009-01-01

The authors have previously developed a novel method for the fabrication of silica/perfluoropolymer nanocomposites, wherein nano-sized silica particles without surface modification were dispersed uniformly through breakdown of loosely packed agglomerates of silica nanoparticles with low fracture strength in a polymer melt during direct melt-compounding. The method consists of two stages; the first stage involves preparation of the loose silica agglomerate, and the second stage involves melt-compounding of a completely hydrophobic perfluoropolymer, PFA (poly(tetrafluoroethylene-co-perfluoropropylvinylether)), with the loose silica agglomerates. By using this simple method without any lipophilic treatment of the silica surfaces, silica nanoparticles with a primary diameter of 190 nm could be dispersed uniformly into the PFA matrix. The main purpose of the present study is to evaluate the melt flow and tensile properties of silica/PFA nanocomposites fabricated by the above method. In order to elucidate the effects of the size of the dispersed silica in the PFA matrix on the properties of the composites, silica/PFA composite samples exhibiting the dispersion of larger-sized silica particle-clusters were fabricated as negative controls of the silica dispersion state. The results obtained under the present experimental conditions showed that the size of the dispersed silica in the PFA matrix exerts a strong influence on the ultimate tensile properties, such as tensile strength and elongation at break, and the melt flow rate (MFR) of the composite materials. The MFR of the silica/PFA nanocomposite became higher than that of the pure PFA without silica addition, although the MFR of the PFA composites containing larger silica particle-clusters became much lower than that of the pure PFA. Furthermore, uniform dispersion of isolated silica nanoparticles was found to improve not only the Young's modulus but also the ultimate tensile properties of the composite.

Long-Term Mechanical Behavior of Nano Silica Sol Grouting

Science.gov (United States)

Zhang, Nong; Zhang, Chenghao; Qian, Deyu; Han, Changliang; Yang, Sen

2018-01-01

The longevity of grouting has a significant effect on the safe and sustainable operation of many engineering projects. A 500-day experiment was carried out to study the long-term mechanical behavior of nano silica sol grouting. The nano silica sol was activated with different proportions of a NaCl catalyst and cured under fluctuating temperature and humidity conditions. The mechanical parameters of the grout samples were tested using an electrohydraulic uniaxial compression tester and an improved Vicat instrument. Scanning electron microscope, X-ray diffraction, and ultrasonic velocity tests were carried out to analyze the strength change micro-mechanism. Tests showed that as the catalyst dosage in the grout mix is decreased, the curves on the graphs showing changes in the weight and geometric parameters of the samples over time could be divided into three stages, a shrinkage stage, a stable stage, and a second shrinkage stage. The catalyst improved the stability of the samples and reduced moisture loss. Temperature rise was also a driving force for moisture loss. Uniaxial compressive stress-strain curves for all of the samples were elastoplastic. The curves for uniaxial compression strength and secant modulus plotted against time could be divided into three stages. Sample brittleness increased with time and the brittleness index increased with higher catalyst dosages in the latter part of the curing time. Plastic strength-time curves exhibit allometric scaling. Curing conditions mainly affect the compactness, and then affect the strength. PMID:29337897

Long-Term Mechanical Behavior of Nano Silica Sol Grouting

Directory of Open Access Journals (Sweden)

Dongjiang Pan

2018-01-01

Full Text Available The longevity of grouting has a significant effect on the safe and sustainable operation of many engineering projects. A 500-day experiment was carried out to study the long-term mechanical behavior of nano silica sol grouting. The nano silica sol was activated with different proportions of a NaCl catalyst and cured under fluctuating temperature and humidity conditions. The mechanical parameters of the grout samples were tested using an electrohydraulic uniaxial compression tester and an improved Vicat instrument. Scanning electron microscope, X-ray diffraction, and ultrasonic velocity tests were carried out to analyze the strength change micro-mechanism. Tests showed that as the catalyst dosage in the grout mix is decreased, the curves on the graphs showing changes in the weight and geometric parameters of the samples over time could be divided into three stages, a shrinkage stage, a stable stage, and a second shrinkage stage. The catalyst improved the stability of the samples and reduced moisture loss. Temperature rise was also a driving force for moisture loss. Uniaxial compressive stress-strain curves for all of the samples were elastoplastic. The curves for uniaxial compression strength and secant modulus plotted against time could be divided into three stages. Sample brittleness increased with time and the brittleness index increased with higher catalyst dosages in the latter part of the curing time. Plastic strength-time curves exhibit allometric scaling. Curing conditions mainly affect the compactness, and then affect the strength.

Pyrolytic carbon membranes containing silica: morphological approach on gas transport behavior

Science.gov (United States)

Park, Ho Bum; Lee, Sun Yong; Lee, Young Moo

2005-04-01

Pyrolytic carbon membrane containing silica (C-SiO 2) is a new-class material for gas separation, and in the present work we will deal with it in view of the morphological changes arising from the difference in the molecular structure of the polymeric precursors. The silica embedded carbon membranes were fabricated by a predetermined pyrolysis step using imide-siloxane copolymers (PISs) that was synthesized from benzophenone tetracarboxylic dianhydrides (BTDA), 4,4'-oxydianiline (ODA), and amine-terminated polydimethylsiloxane (PDMS). To induce different morphologies at the same chemical composition, the copolymers were prepared using one-step (preferentially a random segmented copolymer) sand two-step polymerization (a block segmented copolymer) methods. The polymeric precursors and their pyrolytic C-SiO 2 membranes were analyzed using thermal analysis, atomic force microscopy, and transmission electron microscopy, etc. It was found that the C-SiO 2 membrane derived from the random PIS copolymer showed a micro-structure containing small well-dispersed silica domains, whereas the C-SiO 2 membrane from the block PIS copolymer exhibited a micro-structure containing large silica domains in the continuous carbon matrix. Eventually, the gas transport through these C-SiO 2 membranes was significantly affected by the morphological changes of the polymeric precursors.

Nano-amylose-2,3-bis(3,5-dimethylphenylcarbamate)-silica hybrid sol immobilized on open tubular capillary column for capillary electrochromatography enantioseparation.

Science.gov (United States)

Sun, Yaming; Wu, Qi; Shi, Xiaofeng; Gao, Jie; Dong, Shuqing; Zhao, Liang

2018-04-01

The chiral organic-inorganic hybrid materials can exhibit a high loading, and the chiral selector nanoparticles can create efficient stationary phases for open-tubular capillary electrochromatography (OT-CEC). Hence, a novel protocol for the preparation of an OT column coated with nano-amylose-2,3-bis(3,5-dimethylphenylcarbamate) (nano-ABDMPC)-silica hybrid sol through in situ layer-by-layer self-assembly method was developed for CEC enantioseparation. By controlling the assembly cycle number of nano-ABDMPC-silica hybrid sol, a homogeneous, dense and stable coating was successfully prepared, which was confirmed by SEM and elemental analysis. As the main parameter influencing the chiral separating effect, the nano-ABDMPC bearing 3-(triethoxysilyl)propyl residues concentration was investigated. The experimental results showed that 10.0 mg/mL nano-ABDMPC bearing 3-(triethoxysilyl)propyl residues coated OT capillary column possessed chiral recognition ability toward the six enantiomers (phenylalanine, tyrosine, tryptophan, phenethyl alcohol, 1-phenyl-2-propanol, and Tröger's base) at some of the different conditions tested. Additionally, the coated OT column revealed adequate repeatability concerning run-to-run, day-to-day and column-to-column. These results demonstrated the promising applicability of nano-ABDMPC-silica hybrid sol coated OT column in CEC enantioseparations. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

A nano-bio interfacial protein corona on silica nanoparticle.

Science.gov (United States)

Zhang, Hongyan; Peng, Jiaxi; Li, Xin; Liu, Shengju; Hu, Zhengyan; Xu, Guiju; Wu, Ren'an

2018-07-01

Nano-bio interaction takes the crucial role in bio-application of nanoparticles. The systematic mapping of interfacial proteins remains the big challenge as low level of proteins within interface regions and lack of appropriate technology. Here, a facile proteomic strategy was developed to characterize the interfacial protein corona (noted as IPC) that has strong interactions with silica nanoparticle, via the combination of the vigorous elution with high concentration sodium dodecyl sulfate (SDS) and the pre-isolation of sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE). The trace level IPCs for silica nanoparticle were thus qualitatively and quantitatively identified. Bioinformatics analyses revealed the intrinsic compositions, relevance and potential regularity addressing the strong interactions between IPC and nanoparticle. This strategy in determining IPCs is opening an avenue to give a deep insight to understand the interaction between proteins and not only nanoparticles but also other bulk materials. Copyright © 2018 Elsevier B.V. All rights reserved.

Prediction Surface Morphology of Nanostructure Fabricated by Nano-Oxidation Technology.

Science.gov (United States)

Huang, Jen-Ching; Chang, Ho; Kuo, Chin-Guo; Li, Jeen-Fong; You, Yong-Chin

2015-12-04

Atomic force microscopy (AFM) was used for visualization of a nano-oxidation technique performed on diamond-like carbon (DLC) thin film. Experiments of the nano-oxidation technique of the DLC thin film include those on nano-oxidation points and nano-oxidation lines. The feature sizes of the DLC thin film, including surface morphology, depth, and width, were explored after application of a nano-oxidation technique to the DLC thin film under different process parameters. A databank for process parameters and feature sizes of thin films was then established, and multiple regression analysis (MRA) and a back-propagation neural network (BPN) were used to carry out the algorithm. The algorithmic results are compared with the feature sizes acquired from experiments, thus obtaining a prediction model of the nano-oxidation technique of the DLC thin film. The comparative results show that the prediction accuracy of BPN is superior to that of MRA. When the BPN algorithm is used to predict nano-point machining, the mean absolute percentage errors (MAPE) of depth, left side, and right side are 8.02%, 9.68%, and 7.34%, respectively. When nano-line machining is being predicted, the MAPEs of depth, left side, and right side are 4.96%, 8.09%, and 6.77%, respectively. The obtained data can also be used to predict cross-sectional morphology in the DLC thin film treated with a nano-oxidation process.

Effect of Addition of Colloidal Silica to Films of Polyimide, Polyvinylpyridine, Polystyrene, and Polymethylmethacrylate Nano-Composites

Directory of Open Access Journals (Sweden)

Soliman Abdalla

2016-02-01

Full Text Available Nano-composite films have been the subject of extensive work for developing the energy-storage efficiency of electrostatic capacitors. Factors such as polymer purity, nanoparticle size, and film morphology drastically affect the electrostatic efficiency of the dielectric material that forms the insulating film between the conductive electrodes of a capacitor. This in turn affects the energy storage performance of the capacitor. In the present work, we have studied the dielectric properties of four highly pure amorphous polymer films: polymethyl methacrylate (PMMA, polystyrene, polyimide and poly-4-vinylpyridine. Comparison between the dielectric properties of these polymers has revealed that the higher breakdown performance is a character of polyimide (PI and PMMA. Also, our experimental data shows that adding colloidal silica to PMMA and PI leads to a net decrease in the dielectric properties compared to the pure polymer.

Some Properties of Carbon Fiber Reinforced Magnetic Reactive Powder Concrete Containing Nano Silica

Directory of Open Access Journals (Sweden)

Zain El-Abdin Raouf

2016-08-01

Full Text Available This study involves the design of 24 mixtures of fiber reinforced magnetic reactive powder concrete containing nano silica. Tap water was used for 12 of these mixtures, while magnetic water was used for the others. The nano silica (NS with ratios (1, 1.5, 2, 2.5 and 3 % by weight of cement, were used for all the mixtures. The results have shown that the mixture containing 2.5% NS gives the highest compressive strength at age 7 days. Many different other tests were carried out, the results have shown that the carbon fiber reinforced magnetic reactive powder concrete containing 2.5% NS (CFRMRPCCNS had higher compressive strength, modulus of rupture, splitting tension, stress in compression and strain in compression than the corresponding values for the carbon fiber reinforced nonmagnetic reactive powder concrete containing the same ratio of NS (CFRNRPCCNS. The percentage increase in these values for CFRMRPCCNS were (22.37, 17.96, 19.44, 6.44 and 25.8 % at 28 days respectively, as compared with the corresponding CFRNRPCCNS mixtures.

Magnetic polymer-silica composites as bioluminescent sensors for bilirubin detection

Energy Technology Data Exchange (ETDEWEB)

Timin, Alexander S., E-mail: a_timin@mail.ru [Inorganic Chemistry Department, Ivanovo State University of Chemistry and Technology (ISUCT), 7, Sheremetevsky prosp., 153000, Ivanovo (Russian Federation); RASA Center in Tomsk, Tomsk Polytechnic University, pros. Lenina, 30, Tomsk (Russian Federation); Solomonov, Alexey V. [Inorganic Chemistry Department, Ivanovo State University of Chemistry and Technology (ISUCT), 7, Sheremetevsky prosp., 153000, Ivanovo (Russian Federation); Department of Materials and Interfaces, Weizmann Institute of Science, Rehovot, 7610001 (Israel); Kumagai, Akiko; Miyawaki, Atsushi [Cell Function Dynamics, Brain Science Institute RIKEN, 2-1 Hirosawa, Wako-city, Saitama, 351-0198 (Japan); Khashirova, Svetlana Yu; Zhansitov, Azamat [Kabardino-Balkar State University, 173 Chernyshevskogo St., Nal' chik, 360004, Kabardino-Balkaria (Russian Federation); Rumyantsev, Evgeniy V. [Inorganic Chemistry Department, Ivanovo State University of Chemistry and Technology (ISUCT), 7, Sheremetevsky prosp., 153000, Ivanovo (Russian Federation)

2016-11-01

The synthesis of multifunctional nano-sized materials is leading to the rapid development of key application, including improved drug delivery, bioimaging and protein separation. In this work, magnetic silica particles modified with novel guanidine containing co-polymers were manufactured via sol-gel method. To evaluate the chemical composition of our prepared samples, FT-IR spectroscopy and thermogravimetry were conducted. Scanning electron microscopy was used in order to investigate the morphology of final products after modification by guanidine containing co-polymers and iron nanoparticles. In addition, the surface of polymer-silica composites was functionalized by the novel bilirubin-inducible fluorescent protein UnaG. In an aqueous bilirubin solution, the silica particles decorated with the polymer-UnaG have showed bright fluorescence. Synthesis and characterization of these hybrid materials allow developing of new multifunctional nano-sized materials, which will be used for detection and separation of bilirubin, a lipophilic heme catabolite that is a clinical diagnostic for liver function. - Highlights: • Novel magnetic silicas grafted by guanidine containing co-polymers were prepared. • Unag protein was effectively loaded into polymer coated silicas. • The fluorescent properties depend on content of bilirubin.

Magnetic polymer-silica composites as bioluminescent sensors for bilirubin detection

International Nuclear Information System (INIS)

Timin, Alexander S.; Solomonov, Alexey V.; Kumagai, Akiko; Miyawaki, Atsushi; Khashirova, Svetlana Yu; Zhansitov, Azamat; Rumyantsev, Evgeniy V.

2016-01-01

The synthesis of multifunctional nano-sized materials is leading to the rapid development of key application, including improved drug delivery, bioimaging and protein separation. In this work, magnetic silica particles modified with novel guanidine containing co-polymers were manufactured via sol-gel method. To evaluate the chemical composition of our prepared samples, FT-IR spectroscopy and thermogravimetry were conducted. Scanning electron microscopy was used in order to investigate the morphology of final products after modification by guanidine containing co-polymers and iron nanoparticles. In addition, the surface of polymer-silica composites was functionalized by the novel bilirubin-inducible fluorescent protein UnaG. In an aqueous bilirubin solution, the silica particles decorated with the polymer-UnaG have showed bright fluorescence. Synthesis and characterization of these hybrid materials allow developing of new multifunctional nano-sized materials, which will be used for detection and separation of bilirubin, a lipophilic heme catabolite that is a clinical diagnostic for liver function. - Highlights: • Novel magnetic silicas grafted by guanidine containing co-polymers were prepared. • Unag protein was effectively loaded into polymer coated silicas. • The fluorescent properties depend on content of bilirubin.

Effect of Synthesis Time on Morphology of Hollow Porous Silica Microspheres

Directory of Open Access Journals (Sweden)

Qian CHEN

2012-03-01

Full Text Available Hollow porous silica microspheres may be applicable as containers for the controlled release in drug delivery systems (DDS, foods, cosmetics, agrochemical, textile industry, and in other technological encapsulation use. In order to control the surface morphological properties of the silica microspheres, the effect of synthesis time on their formation was studied by a method of water-in-oil (W/O emulsion mediated sol-gel techniques. An aqueous phase of water, ammonium hydroxide and a surfactant Tween 20 was emulsified in an oil phase of 1-octanol with a stabilizer, hydroxypropyl cellulose (HPC, and a surfactant, sorbitan monooleate (Span 80 with low hydrophile-lipophile balance (HLB value. Tetraethyl orthosilicate (TEOS as a silica precursor was added to the emulsion. The resulting silica particles at different synthesis time 24, 48, and 72 hours were air-dried at room temperature and calcinated at 773 K for 3 hours. The morphology of the particles was characterized by scanning electron microscopy and the particle size distribution was measured by laser diffraction. The specific surface areas were studied by 1-point BET method, and pore sizes were measured by Image Tool Software. Both dense and porous silica microspheres were observed after all three syntheses. Hollow porous silica microspheres were formed at 24 and 48 hours synthesis time. Under base catalyzed sol-gel solution, the size of silica particles was in the range of 5.4 μm to 8.2 μm, and the particles had surface area of 111 m2/g – 380 m2/g. The longer synthesis time produced denser silica spheres with decreased pore sizes.DOI: http://dx.doi.org/10.5755/j01.ms.18.1.1344

Surface modification to produce hydrophobic nano-silica particles using sodium dodecyl sulfate as a modifier

Energy Technology Data Exchange (ETDEWEB)

Qiao, Bing; Liang, Yong; Wang, Ting-Jie, E-mail: wangtj@tsinghua.edu.cn; Jiang, Yanping

2016-02-28

Graphical abstract: Nano silica particle was modified to produce hydrophobic surface with contact angle of 107° using the water soluble SDS as a modifier through a new route. The grafted density reached 1.82–2 nm. Brønsted acid sites supply proton to react with SDS via generating carbocation, forming a Si–O–C structure. - Highlights: • Silica was modified to produce hydrophobic surface using SDS as modifier. • The route is free of organic solvent and gets perfect contact of SDS and silica. • Contact angle of modified silica particles reached 107°. • Grafted density on the silica surface reached 1.82 SDS nm{sup −2}. • Brønsted acid sites supply proton to react with SDS via generating carbocation. - Abstract: Hydrophobic silica particles were prepared using the surfactant sodium dodecyl sulfate (SDS) as a modifier by a new route comprising three processes, namely, aqueous mixing, spray drying and thermal treatment. Since SDS dissolves in water, this route is free of an organic solvent and gave a perfect dispersion of SDS, that is, there was excellent contact between SDS and silica particles in the modification reaction. The hydrophobicity of the modified surface was verified by the contact angle of the nano-sized silica particles, which was 107°. The SDS grafting density reached 1.82 nm{sup −2}, which is near the highest value in the literature. The optimal parameters of the SDS/SiO{sub 2} ratio in the aqueous phase, process temperature and time of thermal treatment were determined to be 20%, 200 °C and 30 min, respectively. The grafting mechanism was studied by comparing the modification with that on same sized TiO{sub 2} particles, which indicated that the protons of the Brønsted acid sites on the surface of SiO{sub 2} reacted with SDS to give a carbocation which then formed a Si–O–C structure. This work showed that the hydrophilic surface of silica can be modified to be a hydrophobic surface by using a water soluble modifier SDS in a

Effects of a Nano-Silica Additive on the Rock Erosion Characteristics of a SC-CO2 Jet under Various Operating Conditions

Directory of Open Access Journals (Sweden)

Man Huang

2017-02-01

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

Morphologies of fission fragment impacts in diamond and silica

International Nuclear Information System (INIS)

Gammage, R.B.; Espinosa, G.; Vazquez, C.; Moreno, A.

2005-01-01

The morphologies of fission-fragment impact craters in diamond and silica were investigated by atomic force microscopy. The impacts produced micron-sized craters that were especially obvious in diamond; irradiations in air may have allowed the cratering in carbon to be oxidally enhanced. The eject deposit preferentially at ordered sites and have the appearance of hillocks of a few tenths microns in size. On quartz, the hillocks have a parallel-perpendicular, x-y pattern; on diamond, the hillocks form one dimensional, parallel rows. In contrast, the hillocks on amorphous silica fiber show a random pattern. (Author)

Molecular dynamics simulation of potentiometric sensor response: the effect of biomolecules, surface morphology and surface charge.

Science.gov (United States)

Lowe, B M; Skylaris, C-K; Green, N G; Shibuta, Y; Sakata, T

2018-05-10

The silica-water interface is critical to many modern technologies in chemical engineering and biosensing. One technology used commonly in biosensors, the potentiometric sensor, operates by measuring the changes in electric potential due to changes in the interfacial electric field. Predictive modelling of this response caused by surface binding of biomolecules remains highly challenging. In this work, through the most extensive molecular dynamics simulation of the silica-water interfacial potential and electric field to date, we report a novel prediction and explanation of the effects of nano-morphology on sensor response. Amorphous silica demonstrated a larger potentiometric response than an equivalent crystalline silica model due to increased sodium adsorption, in agreement with experiments showing improved sensor response with nano-texturing. We provide proof-of-concept that molecular dynamics can be used as a complementary tool for potentiometric biosensor response prediction. Effects that are conventionally neglected, such as surface morphology, water polarisation, biomolecule dynamics and finite-size effects, are explicitly modelled.

Evolution of Morphology and Crystallinity of Silica Minerals Under Hydrothermal Conditions

Science.gov (United States)

Isobe, H.

2011-12-01

Silica minerals are quite common mineral species in surface environment of the terrestrial planets. They are good indicator of terrestrial processes including hydrothermal alteration, diagenesis and soil formation. Hydrothermal quartz, metastable low temperature cristobalite and amorphous silica show characteristic morphology and crystallinity depending on their formation processes and kinetics under wide range of temperature, pressure, acidity and thermal history. In this study, silica minerals produced by acidic hydrothermal alteration related to volcanic activities and hydrothermal crystallization experiments from diatom sediment are examined with crystallographic analysis and morphologic observations. Low temperature form of cistobalite is a metastable phase and a common alteration product occured in highly acidic hydrothermal environment around fumaroles in geothermal / volcanic areas. XRD analysis revealed that the alteration degree of whole rock is represented by abundance of cristobalite. Detailed powder XRD analysis show that the primary diffraction peak of cristobalite composed with two or three phases with different d-spacing and FWHM by peak profile fitting analysis. Shorter d-spacing and narrower FWHM cristobalite crystallize from precursor materials with less-crystallized, longer d-spacing and wider FWHM cristobalite. Textures of hydrothermal cristobalite in altered rock shows remnant of porphylitic texture of the host rock, pyroxene-amphibole andesite. Diatom has amorphous silica shell and makes diatomite sediment. Diatomite found in less diagenetic Quarternary formation keeps amorphous silica diatom shells. Hydrothermal alteration experiments of amorphous silica diatomite sediment are carried out from 300 °C to 550 °C. Mineral composition of run products shows crystallization of cristobalite and quartz progress depending on temperature and run durations. Initial crystallization product, cristobalite grains occur as characteristic lepispheres and

Surface characterization of polyethylene terephthalate/silica nanocomposites

Energy Technology Data Exchange (ETDEWEB)

Parvinzadeh, Mazeyar, E-mail: mparvinzadeh@gmail.com [Department of Textile, Islamic Azad University, Science and Research Branch, Tehran (Iran, Islamic Republic of); Moradian, Siamak [Department of Polymer and Color Engineering, Amirkabir University of Technology, P.O. Box 15875-4413, Tehran (Iran, Islamic Republic of); Rashidi, Abosaeed [Department of Textile, Islamic Azad University, Science and Research Branch, Tehran (Iran, Islamic Republic of); Yazdanshenas, Mohamad-Esmail [Department of Textile, Islamic Azad University, Yazd Branch, Yazd (Iran, Islamic Republic of)

2010-02-15

Poly(ethylene terephthalate) (PET) based nanocomposites containing hydrophilic (i.e. Aerosil 200 or Aerosil TT 600) or hydrophobic (i.e. Aerosil R 972) nano-silica were prepared by melt compounding. Influence of nano-silica type on surface properties of the resultant nanocomposites was investigated by the use of Fourier transform infrared spectroscopy (FTIR), atomic force microscopy (AFM), contact angle measurement (CAM), scanning electron microscopy (SEM) and reflectance spectroscopy (RS). The possible interaction between nano-silica particles and PET functional groups at bulk and surface were elucidated by transmission FTIR and FTIR-ATR spectroscopy, respectively. AFM studies of the resultant nanocomposites showed increased surface roughness compared to pure PET. Contact angle measurements of the resultant PET composites demonstrated that the wettability of such composites depends on surface treatment of the particular nano-silica particles used. SEM images illustrated that hydrophilic nano-silica particles tended to migrate to the surface of the PET matrix.

Cobalt oxide polymorph growth on electrostatic self-assembled nanoparticle arrays for dually tunable nano-textures

International Nuclear Information System (INIS)

Bulliard, Xavier; Benayad, Anass; Lee, Kwang-Hee; Choi, Yun-Hyuk; Lee, Jae Cheol; Park, Jong-Jin; Kim, Jong-Min

2011-01-01

We report on a method for surface nano-texturing on a plastic substrate. Nano-objects with a silica nanoparticle core and a textured cobalt oxide crown are created with selectable density on the plastic substrate. The resulting dual morphology is easily tuned over large areas, either by changing the parameters directing nanoparticle deposition through electrostatic self-arrangement for nano-object density control, or the parameter directing cobalt oxide deposition for shape control. The entire process takes place at room temperature, with no chemicals harmful to the plastic substrate. The ready modulation of the dual morphology is used to control the wettability properties of the plastic film, which is covered by nano-objects.

Effects of confinement in meso-porous silica and carbon nano-structures

International Nuclear Information System (INIS)

Leon, V.

2006-07-01

Physico-chemical properties of materials can be strongly modified by confinement because of the quantum effects that appear at such small length scales and also because of the effects of the confinement itself. The aim of this thesis is to show that both the nature of the confining material and the size of the pores and cavities have a strong impact on the confined material. We first show the effect of the pore size of the host meso-porous silica on the temperature of the solid-solid phase transition of silver selenide, a semiconducting material with enhanced magnetoresistive properties under non-stoichiometric conditions. Narrowing the pores from 20 nm to 2 nm raises the phase transition temperature from 139 C to 146 C. This result can be explained by considering the interaction between the confining and confined materials as a driving force. The effects of confinement are also studied in the case of hydrogen and deuterium inside cavities of organized carbon nano-structures. The effects that appear in the adsorption/desorption cycles are much stronger with carbon nano-horns as the host material than with C60 pea-pods and single-walled carbon nano-tubes. (author)

Effect of polyvinylpyrrolidone on mesoporous silica morphology and esterification of lauric acid with 1-butanol catalyzed by immobilized enzyme

Energy Technology Data Exchange (ETDEWEB)

Zhang, Jinyu; Zhou, Guowei, E-mail: guoweizhou@hotmail.com; Jiang, Bin; Zhao, Minnan; Zhang, Yan

2014-05-01

Mesoporous silica materials with a range of morphology evolution, i.e., from curved rod-shaped mesoporous silica to straight rod-shaped mesoporous silica, were successfully prepared using polyvinylpyrrolidone (PVP) and triblock copolymer as dual template. The effects of PVP molecular weight and concentration on mesoporous silica structure parameters were studied. Results showed that surface area and pore volume continuously decreased with increased PVP molecular weight. Mesoporous silica prepared with PVP K30 also possessed larger pore diameter, interplanar spacing (d{sub 100}), and cell parameter (a{sub 0}) than that prepared with PVP K15 and PVP K90. In addition, with increased PVP concentration, d{sub 100} and a{sub 0} continuously decreased. The mechanism of morphology evolution caused by the change in PVP concentration was investigated. The conversion rate of lauric acid with 1-butanol catalyzed by immobilized Porcine pancreatic lipase (PPL) was also evaluated. Results showed that PPL immobilized on amino-functionalized straight rod-shaped mesoporous silica maintained 50% of its esterification conversion rate even after five cycles of use with a maximum conversion rate was about 90.15%. - Graphical abstract: Curved rod-shaped mesoporous silica can be obtained at low and the highest PVP concentration, while straight rod-shaped mesoporous silica can be obtained at higher PVP concentration. - Highlights: • Mesoporous silica with morphology evolution from CRMS to SRMS were prepared. • Effects of PVP molecular weight and concentration on silica morphology were studied. • A possible mechanism for the formation of morphology evolution SiO{sub 2} was proposed. • Esterification of lauric acid with 1-butanol catalyzed by immobilized PPL.

Synthesis of Nano-Zinc Oxide Loaded on Mesoporous Silica by Coordination Effect and Its Photocatalytic Degradation Property of Methyl Orange.

Science.gov (United States)

Shen, Zhichuan; Zhou, Hongjun; Chen, Huayao; Xu, Hua; Feng, Chunhua; Zhou, Xinhua

2018-05-09

Salicylaldimine-modified mesoporous silica (Sal-MCM-3 and Sal-MCM-9) was prepared through a co-condensation method with different amounts of added salicylaldimine. With the coordination from the salicylaldimine, zinc ions were impregnated on Sal-MCM-3 and Sal-MCM-9. Then, Zn-Sal-MCM-3 and Zn-Sal-MCM-9 were calcined to obtain nano-zinc oxide loaded on mesoporous silica (ZnO-MCM-3 and ZnO-MCM-9). The material structures were systematically studied by Fourier transform infrared spectroscopy (FTIR), N₂ adsorption/desorption measurements, X-ray powder diffraction (XRD), zeta potential, scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), ultraviolet diffused reflectance spectrum (UV-vis DRS), and thermogravimetry (TGA). Methyl orange (MO) was used to investigate the photocatalysis behavior of ZnO-MCM-3 and ZnO-MCM-9. The results confirmed that nano ZnO was loaded in the channels as well as the outside surface of mesoporous silica (MCM-41). The modification of salicylaldimine helped MCM-41 to load more nano ZnO on MCM-41. When the modification amount of salicylaldimine was one-ninth and one-third of the mass of the silicon source, respectively, the load of nano ZnO on ZnO-MCM-9 and ZnO-MCM-3 had atomic concentrations of 1.27 and 2.03, respectively. ZnO loaded on ZnO-MCM-9 had a wurtzite structure, while ZnO loaded on ZnO-MCM-3 was not in the same crystalline group. The blocking effect caused by nano ZnO in the channels reduced the orderliness of MCM-41. The photodegradation of MO can be divided in two processes, which are mainly controlled by the surface areas of ZnO-MCM and the loading amount of nano ZnO, respectively. The pseudo-first-order model was more suitable for the photodegradation process.

Effect of colloidal nano-silica on the mechanical and physical behaviour of waste-glass cement mortar

International Nuclear Information System (INIS)

Aly, M.; Hashmi, M.S.J.; Olabi, A.G.; Messeiry, M.; Abadir, E.F.; Hussain, A.I.

2012-01-01

Highlights: → Glass powder (GP) and nano-silica (CS) were used as a partial cement replacement in cement mortar (CM). → No damaging effect can be detected due to the reaction between GP and CM with particle size up to 75 μm. → Hybrid combination of GP/CS greatly improved mechanical properties and microstructure of CM. -- Abstract: This paper presents a laboratory study of the properties of colloidal nano-silica (CS)/waste glass cement composites. The microstructure, alkali-silica reaction (ASR), and the mechanical properties of cement mortars containing waste glass powder (WG) as a cement replacement with and without CS are investigated and compared with plain mortar. In addition, the hydration of cement compounds was followed by differential thermal analysis (DTA), thermogravimetric analysis (TGA), and X-ray diffraction (XRD). The results show that incorporation of WG has a positive effect on the mechanical properties of cement mortars especially when CS is presented. In addition, the DTA/TGA results and XRD analysis show a reduction in the calcium hydroxide (CH) content in mortars with both WG and a hybrid combination of WG and CS. This confirms the improvement of mechanical properties and the occurrence of the pozzolanic reaction after 28 days of hydration.

FTIR and morphology of liquid epoxidized natural rubber acrylate (LENRA)/silica hybrid composites

International Nuclear Information System (INIS)

Eda Yuhana Ariffin; Azizan Ahmad; Dahlan Mohd; Mahathir Mohamed

2009-01-01

Synthesis of organic-inorganic hybrid composites was carried out by combination of liquid epoxidized natural rubber acrylate (LENRA) and silica. Silica was introduce to the matrix by sol gel technique. The sol-gel technique was employed to prepare silica using tetraethyorthosilicate (TEOS) as precursor. HDDA and irga cure 184 were added to the formulations as reactive diluents and photosensitizer, respectively. The chemical modification was studied by Fourier Transform Infrared (FTIR) and energy dispersive X-ray analysis (EDAX). The morphological studies were conducted by the optical and scanning electron microscopes (SEM). It shows that silica was dispersed very well in the matrix for lower concentration of TEOS while agglomeration occurs at the higher concentration. The average particles size of silica were less than 100 nm. (Author)

Preparation and Properties of Nano Dy/TiO2 Films Supported on High Silica Fiber

Directory of Open Access Journals (Sweden)

HUANG Feng-ping

2017-07-01

Full Text Available In order to improve the photocatalytic degradation performance and stability of nano TiO2, Dy doped TiO2 supported on high silica glass fiber was prepared by microwave-sol method combined with dip-coating method. The samples were analyzed by XRD,SEM,PL,EDS,XPS and other equipments for phase composition of films,surface topography, surface elements and the stability of films. And the effects of pretreatment solution and coating method on the high-silica fiber film were investigated.In addition, the photocatalytic performance of the sample has been investigated by degrading methylene blue. The results show that the catalytic stability of Dy doping TiO2 nanofilms supported on high silica glass fiber can be improved and the degradation of methyl orange can reach 94% in 30min after 5 times of coating treatment.

Electron beam synthesis of silica/nano silver composite and its application in controlling microorganisms in drinking water

International Nuclear Information System (INIS)

Ramnani, S.P.; Biswal, Jayashree; Sabharwal, S.; Rama Rao, K.C.; Sai Prasad, P.

2008-01-01

Silica/nano silver composites were prepared by electron beam (EB) irradiation technique. The solution containing silica nanoparticles and AgNO 3 in various proportion were subjected to EB irradiation. The EB dose delivered was such that all the Ag + is converted into metallic silver. The samples were characterized by XRD, SEM and TEM analysis. The composites were tested for their anti microbial activity in water samples. The results indicated that there is an optimum size of Ag nanoparticles that shows better antimicrobial activity. (author)

Influence of the ammonium hydroxide concentration in morphological control of meso porous silica particles

International Nuclear Information System (INIS)

Yoon, Sukbon; Jung, Chonghun; Yoon, Inho; Kim, Changki; Choi, Wangkyu; Moon, Jeikwon

2012-01-01

The discovery of new M41S meso porous silica families in 1992 extended the applications into much wider pore ranges, bringing in a new prosperous era in porous material research. The synthesis of these meso porous silicas has been mainly accomplished through a self-assembly between surfactant molecules and inorganic species under various pH conditions. Meanwhile, many studies have been conducted on the application as catalysts, adsorbents, and packing materials for separation columns due to their unique properties such as high specific surface area, large pore volume, tuneable pore size, and narrow pore size distribution. The pore sizes of these materials can be easily controlled by changing the alkyl-chain length of the surfactant used. However, the control of the morphology and the pore structure is not so common. The morphological control of these materials in particular is one of the major challenges for their industrial application. Recently, the meso porous silica materials with various shapes such as fibers, films, polyhedral particles, and spheres have been reported. In our previous study, the core-shell nanoparticles with a silica core and a meso porous shell under basic conditions were synthesized using the silica nanoparticles as a core and tetraethyl orthosilicate (TEOS)-cetyltrimethylammonium bromide (CTABr)-NH 4 OH-H 2 O-C 2 H 5 OH system. In this work, we report the synthesis of the most well known hexagonal MCM-41 among three main mesophases in the M41S families using TEOS-CTABr-NH 4 OH-H 2 O system. Also, in the control of the morphology and pore structure of the meso porous silica materials, the influence of the NH 4 OH concentration was investigated

Morphology, thermal, electrical and electrochemical stability of nano

Indian Academy of Sciences (India)

In the present work, an attempt has been made to develop nano aluminium oxide (Al2O3)-filled polyvinyl alcohol (PVA) composite gel electrolytes. Surface morphological studies, thermal behaviour, electrochemical stability and electrical characterization of these composite gel electrolytes have been performed. An increase ...

Synthesis of biocompatible hydrophobic silica-gelatin nano-hybrid by sol-gel process.

Science.gov (United States)

Smitha, S; Shajesh, P; Mukundan, P; Nair, T D R; Warrier, K G K

2007-03-15

Silica-biopolymer hybrid has been synthesised using colloidal silica as the precursor for silica and gelatin as the biopolymer counterpart. The surface modification of the hybrid material has been done with methyltrimethoxysilane leading to the formation of biocompatible hydrophobic silica-gelatin hybrid. Here we are reporting hydrophobic silica-gelatin hybrid and coating precursor for the first time. The hybrid gel has been evaluated for chemical modification, thermal degradation, hydrophobicity, particle size, transparency under the UV-visible region and morphology. FTIR spectroscopy has been used to verify the presence of CH(3) groups which introduce hydrophobicity to the SiO2-MTMS-gelatin hybrids. The hydrophobic property has also been tailored by varying the concentration of methyltrimethoxysilane. Contact angle by Wilhelmy plate method of transparent hydrophobic silica-gelatin coatings has been found to be as high as approximately 95 degrees . Oxidation of the organic group which induces the hydrophobic character occurs at 530 degrees C which indicates that the surface hydrophobicity is retained up to that temperature. Optical transmittance of SiO2-MTMS-gelatin hybrid coatings on glass substrates has been found to be close to 100% which will enable the hybrid for possible optical applications and also for preparation of transparent biocompatible hydrophobic coatings on biological substrates such as leather.

Synthesis and photoluminescence enhancement of nano-PAA-ZnCl_2 with controllable dimension and morphology

International Nuclear Information System (INIS)

Wu, Jianguo; Wang, Kaige; Zhou, Yukun; Wang, Shuang; Zhang, Chen; Wang, Guiren

2016-01-01

Highlights: • One kind of large area nano-PAA-ZnCl_2 composite film is fabricated, its dimension and morphology is controllable. The properties of nano-composite films have been heavily influenced by the concentration of initial ZnCl_2 solution, the depth of nano-PAAM substrate and the growth time of ZnCl_2 crystals. • At room temperature, the nano-PAA-ZnCl_2 film has the same excitation center (335 nm) and emission center (430 nm) as the nano-PAAM substrate, and the PL intensities can be doubly enhanced. • After annealing at 500 °C, the emission peak spectra of the nano-composite films stabilized at 385 nm, 402 nm, and 430 nm. - Abstract: One kind of ZnCl_2 nano-films with controllable dimension and morphology is successfully synthesized on the top surface of nano-porous anodic alumina membrane (nano-PAAM) by self-organized method. The nano-PAA-ZnCl_2 composite films are characterized by field emission scanning electron microscopy, energy dispersive spectrometer, and laser confocal Raman spectroscopy. The results indicate that the concentration of initial ZnCl_2 solution, the depth of nano-PAAM substrate and the growth time of ZnCl_2 crystals have important influences on the properties of nano-composite films. Furthermore, the characteristics of nano-composites such as the photoluminescence (PL) spectra are investigated. Compared with the nano-PAAM substrate, at room temperature, all of the nano-PAA-ZnCl_2 composite films have both the same excitation center (335 nm) and emission center (430 nm), no matter what the nano-composite morphologies being; and the PL intensity of nano-PAA-ZnCl_2 composite films are all enhanced and the maximum enhancement is two times; after annealing at 500 °C, the emission spectra of the nano-composite films stabilized at the 385 nm, 402 nm and 430 nm. The research provides a new, simple, economical and practical technology to fabricate nano-PAA composite films with higher luminousintensity.

Effect of addition of different nano-clays on the fumed silica-polyethylene glycol based shear-thickening fluids

Science.gov (United States)

Singh, Mansi; Mehta, Rajeev; Verma, Sanjeev K.; Biswas, Ipsita

2018-01-01

A comparative study of the rheology of shear thickening suspensions of 20% fumed silica in polyethylene glycol (PEG200) with different nano clays as additives has been done. The nano-clays used are montmorillonite (MMT), Closite15A, Kaolin and Halloysite clay. The objective was to study the effect of relatively cost-effective clays as a partial substitute of silica. Specifically, the effect of type, concentration, temperature and frequency were considered. The results indicate that the shear thickening properties of Closite15A as additive in temperature ranges of 25 °C-45 °C performs the best and Halloysite performs best at higher (55 °C) and lower temperatures (5, 15 °C). The elasticity effects in dynamic experiments were markedly enhanced by Halloysite clay addition. Addition of MMT, however, led to insignificant enhancement in critical viscosity in steady-state as well as dynamic state-rheology. Interestingly, shear thickening fluid (STF) with all clay except MMT was stable after storing for more than a month. These findings indicate that the introduction of nano-clay as additives is a promising and cost effective method for enhancing the STF behavior which can be utilized in high impact resistant (about 3000% strain and 300 rad s-1 frequency) applications.

Low-temperature oxidation effects on the morphological and structural properties of hexagonal Zn nano disks

Energy Technology Data Exchange (ETDEWEB)

Lopez, R.; Villa S, G.; Rosales D, J. [Tecnologico de Estudios Superiores de Jocotitlan, Carretera Toluca-Atlacomulco Km 44.8, Jocotitlan, Estado de Mexico (Mexico); Vigueras S, E.; Hernandez L, S. [Universidad Autonoma del Estado de Mexico, Laboratorio de Investigacion y Desarrollo de Materiales Avanzados, Paseo Colon esquina Paseo Tollocan, Toluca, Estado de Mexico (Mexico); Acuna, P. [Universidad Autonoma del Estado de Mexico, Programa de Doctorado en Ciencia de Materiales, Paseo Colon esquina Paseo Tollocan, Toluca, Estado de Mexico (Mexico); Argueta V, A.; Colin B, N., E-mail: lorr810813@gmail.com [Tecnologico de Estudios Superiores de Jocotitlan, Programa de Ingenieria Mecatronica, Carretera Toluca-Atlacomulco Km 44.8, Jocotitlan, Estado de Mexico (Mexico)

2017-11-01

Ambient-atmosphere oxidation in the temperature range of 90-450 degrees Celsius was performed over Zn films composed by well-faceted hexagonal nano disks, which were deposited by thermal evaporation. Morphological and structural properties of oxidized Zn nano disks were studied by scanning electron microscopy, transmission electron microscopy, energy dispersive spectroscopy, X-ray diffraction and Raman scattering measurements. It was found that Zn nano disks keep its original shape only when they are annealed at 90 or 150 degrees Celsius. Smooth oxidation occurred only on the rectangular faces of Zn nano disks heated at 150 degrees Celsius. Thermal oxidation at 250 degrees Celsius favored growth of Zn O nano needles over the surface of the Zn nano disks. Hexagonal-shape of Zn nano disks was transformed completely into a complex morphology composed by different shaped particles, with further increase in oxidation temperature to 450 degrees Celsius. (Author)

Low-temperature oxidation effects on the morphological and structural properties of hexagonal Zn nano disks

International Nuclear Information System (INIS)

Lopez, R.; Villa S, G.; Rosales D, J.; Vigueras S, E.; Hernandez L, S.; Acuna, P.; Argueta V, A.; Colin B, N.

2017-01-01

Ambient-atmosphere oxidation in the temperature range of 90-450 degrees Celsius was performed over Zn films composed by well-faceted hexagonal nano disks, which were deposited by thermal evaporation. Morphological and structural properties of oxidized Zn nano disks were studied by scanning electron microscopy, transmission electron microscopy, energy dispersive spectroscopy, X-ray diffraction and Raman scattering measurements. It was found that Zn nano disks keep its original shape only when they are annealed at 90 or 150 degrees Celsius. Smooth oxidation occurred only on the rectangular faces of Zn nano disks heated at 150 degrees Celsius. Thermal oxidation at 250 degrees Celsius favored growth of Zn O nano needles over the surface of the Zn nano disks. Hexagonal-shape of Zn nano disks was transformed completely into a complex morphology composed by different shaped particles, with further increase in oxidation temperature to 450 degrees Celsius. (Author)

GREEN SYNTHESIS OF 2-AMINO-3-CYANO-4H-CHROMENES IN WATER USING NANO SILICA-BONDED 5-N-PROPYL-OCTAHYDRO-PYRTMIDO[1,2-4]AZEPINIUM CHLORIDE AS AN EFFECTIVE AND REUSABLE NANO CATALYST

OpenAIRE

ROBABEH, BAHARFAR; SHARIATI, SAKINEH ASGHARIAND NARGES

2015-01-01

Nano silica-bonded 5-n-propyl-octahydro-pyrimido[1,2-a]azepinium chloride (NSB-DBU) is reported as an highly efficient and recyclable nano catalyst for the preparation of 4H-chromene derivatives in aqueous media. This synthetic method offers a simple, mild and time-saving method under entirely green and environmentally friendly conditions.

Hydrophobic and optical characteristics of graphene and graphene oxide films transferred onto functionalized silica particles deposited glass surface

Science.gov (United States)

Yilbas, B. S.; Ibrahim, A.; Ali, H.; Khaled, M.; Laoui, T.

2018-06-01

Hydrophobic and optical transmittance characteristics of the functionalized silica particles on the glass surface prior and after transfer of graphene and graphene oxide films on the surface are examined. Nano-size silica particles are synthesized and functionalized via chemical grafting and deposited onto a glass surface. Graphene film, grown on copper substrate, was transferred onto the functionalized silica particles surface through direct fishing method. Graphene oxide layer was deposited onto the functionalized silica particles surface via spin coating technique. Morphological, hydrophobic, and optical characteristics of the functionalized silica particles deposited surface prior and after graphene and graphene oxide films transfer are examined using the analytical tools. It is found that the functionalized silica particles are agglomerated at the surface forming packed structures with few micro/nano size pores. This arrangement gives rise to water droplet contact angle and contact angle hysteresis in the order of 163° and 2°, respectively, and remains almost uniform over the entire surface. Transferring graphene and depositing graphene oxide films over the functionalized silica particles surface lowers the water droplet contact angle slightly (157-160°) and increases the contact angle hysteresis (4°). The addition of the graphene and graphene oxide films onto the surface of the deposited functionalized silica particles improves the optical transmittance.

Micropatterned Silica Films with Nanohydroxyapatite for Y-TZP Implants.

Science.gov (United States)

Miranda, R B P; Grenho, L; Carvalho, A; Fernandes, M H; Monteiro, F J; Cesar, P F

2018-03-01

This investigation aimed at developing micropatterned silica thin films (MSTFs) containing nanohydroxyapatite (nano-HA) microaggregates that were not completely covered by silica so that they could directly interact with the surrounding cells. The objectives were 1) to evaluate the effect of the presence of 2 films (MSTF with or without nano-HA addition) on the characteristic strength (σ 0 ) and Weibull modulus ( m) of a yttria-stabilized tetragonal zirconia polycrystal (Y-TZP) and 2) to evaluate the effect of these 2 films, as applied onto the Y-TZP surface, on the morphology, orientation, and proliferation of MG63 cells. Sol-gel process and soft lithography were used to apply the MSTF onto the Y-TZP specimens. Three experimental groups were produced: Y-TZP, Y-TZP + MSTF, and Y-TZP + MSTF + sprayed nano-HA. All surfaces were characterized by scanning electron microscopy and energy-dispersive X-ray spectroscopy and tested for 4-point flexural strength ( n = 30) in water at 37 °C. Weibull analysis was used to determine m and σ 0 (maximum likelihood method). In vitro biological behavior was performed with human osteoblast-like cells (MG63). Y-TZP was successfully coated with MSFT and MSFT + nano-HA. Scanning electron microscopy micrographs indicated that the microaggregates of nano-HA were not entirely covered by the silica. There was no statistically significant difference among the experimental groups for σ 0 and m. In the groups containing the films, the cells were elongated and aligned along the lines. The MSFT + nano-HA group showed significantly higher cell metabolic activity than that obtained for the Y-TZP group at day 7. This investigation was successful in producing an MSTF containing nano-HA microaggregates that remained exposed to the environment. The developed films did not jeopardize the structural reliability of a commercial Y-TZP, as confirmed by the Weibull statistics. The MG63 cells seeded over the films became elongated and aligned along the

VOPcPhO:P3HT composite micro-structures with nano-porous surface morphology

Energy Technology Data Exchange (ETDEWEB)

Azmer, Mohamad Izzat [Low Dimensional Materials Research Centre (LDMRC), Department of Physics, Faculty of Science, University of Malaya, 50603 Kuala Lumpur (Malaysia); Ahmad, Zubair, E-mail: zubairtarar@qu.edu.qa [Center for Advanced Materials (CAM), Qatar University, P. O. Box 2713, Doha (Qatar); Sulaiman, Khaulah, E-mail: khaulah@um.edu.my [Low Dimensional Materials Research Centre (LDMRC), Department of Physics, Faculty of Science, University of Malaya, 50603 Kuala Lumpur (Malaysia); Touati, Farid [Department of Electrical Engineering, College of Engineering, Qatar University, P. O. Box 2713, Doha (Qatar); Bawazeer, Tahani M. [Department of Chemistry, Faculty of Applied Science, Umm Al-Qura University, Makkah (Saudi Arabia); Alsoufi, Mohammad S. [Mechanical Engineering Department, College of Engineering and Islamic Architecture, Umm Al-Qura University, Makkah (Saudi Arabia)

2017-03-31

Highlights: • VOPcPhO:P3HT micro-structures with nano-porous surface morphology have been formed. • Multidimensional structures have been formed by electro-spraying technique. • The electro-sprayed films are very promising for the humidity sensors. - Abstract: In this paper, composite micro-structures of Vanadyl 2,9,16,23-tetraphenoxy-29H,31H-phthalocyanine) (VOPcPhO) and Poly (3-hexylthiophene-2,5-diyl) (P3HT) complex with nano-porous surface morphology have been developed by electro-spraying technique. The structural and morphological characteristics of the VOPcPhO:P3HT composite films have been studied by field emission scanning electron microscopy (FESEM) and atomic force microscopy (AFM). The multidimensional VOPcPhO:P3HT micro-structures formed by electro-spraying with nano-porous surface morphology are very promising for the humidity sensors due to the pore sizes in the range of micro to nano-meters scale. The performance of the VOPcPhO:P3HT electro-sprayed sensor is superior in term of sensitivity, hysteresis and response/recovery times as compared to the spin-coated one. The electro-sprayed humidity sensor exhibits ∼3 times and 0.19 times lower hysteresis in capacitive and resistive mode, respectively, as compared to the spin-coated humidity sensor.

Synthesis and photoluminescence enhancement of nano-PAA-ZnCl{sub 2} with controllable dimension and morphology

Energy Technology Data Exchange (ETDEWEB)

Wu, Jianguo [State Key Laboratory of Cultivation Base for Photoelectric Technology and Functional Materials, Laboratory of Optoelectronic Technology of Shaanxi Province, National Center for International Research of Photoelectric Technology & Nano-functional Materials and Application, Institute of Photonics and Photon-Technology, Northwest University, Xi’an 710069 (China); Physics Department, Northwest University, Xi’an 710069 (China); Wang, Kaige, E-mail: wangkg@nwu.edu.cn [State Key Laboratory of Cultivation Base for Photoelectric Technology and Functional Materials, Laboratory of Optoelectronic Technology of Shaanxi Province, National Center for International Research of Photoelectric Technology & Nano-functional Materials and Application, Institute of Photonics and Photon-Technology, Northwest University, Xi’an 710069 (China); Zhou, Yukun; Wang, Shuang; Zhang, Chen [State Key Laboratory of Cultivation Base for Photoelectric Technology and Functional Materials, Laboratory of Optoelectronic Technology of Shaanxi Province, National Center for International Research of Photoelectric Technology & Nano-functional Materials and Application, Institute of Photonics and Photon-Technology, Northwest University, Xi’an 710069 (China); Wang, Guiren [State Key Laboratory of Cultivation Base for Photoelectric Technology and Functional Materials, Laboratory of Optoelectronic Technology of Shaanxi Province, National Center for International Research of Photoelectric Technology & Nano-functional Materials and Application, Institute of Photonics and Photon-Technology, Northwest University, Xi’an 710069 (China); Mechanical Engineering Department & Biomedical Engineering Program, University of South Carolina, Columbia SC 29208 (United States); and others

2016-12-30

Highlights: • One kind of large area nano-PAA-ZnCl{sub 2} composite film is fabricated, its dimension and morphology is controllable. The properties of nano-composite films have been heavily influenced by the concentration of initial ZnCl{sub 2} solution, the depth of nano-PAAM substrate and the growth time of ZnCl{sub 2} crystals. • At room temperature, the nano-PAA-ZnCl{sub 2} film has the same excitation center (335 nm) and emission center (430 nm) as the nano-PAAM substrate, and the PL intensities can be doubly enhanced. • After annealing at 500 °C, the emission peak spectra of the nano-composite films stabilized at 385 nm, 402 nm, and 430 nm. - Abstract: One kind of ZnCl{sub 2} nano-films with controllable dimension and morphology is successfully synthesized on the top surface of nano-porous anodic alumina membrane (nano-PAAM) by self-organized method. The nano-PAA-ZnCl{sub 2} composite films are characterized by field emission scanning electron microscopy, energy dispersive spectrometer, and laser confocal Raman spectroscopy. The results indicate that the concentration of initial ZnCl{sub 2} solution, the depth of nano-PAAM substrate and the growth time of ZnCl{sub 2} crystals have important influences on the properties of nano-composite films. Furthermore, the characteristics of nano-composites such as the photoluminescence (PL) spectra are investigated. Compared with the nano-PAAM substrate, at room temperature, all of the nano-PAA-ZnCl{sub 2} composite films have both the same excitation center (335 nm) and emission center (430 nm), no matter what the nano-composite morphologies being; and the PL intensity of nano-PAA-ZnCl{sub 2} composite films are all enhanced and the maximum enhancement is two times; after annealing at 500 °C, the emission spectra of the nano-composite films stabilized at the 385 nm, 402 nm and 430 nm. The research provides a new, simple, economical and practical technology to fabricate nano-PAA composite films with higher

Controlled deposition of functionalized silica coated zinc oxide nano-assemblies at the air/water interface for blood cancer detection

Energy Technology Data Exchange (ETDEWEB)

Pandey, Chandra Mouli [Biomedical Instrumentation Section, CSIR-National Physical Laboratory, New Delhi 110012 (India); Nanobioelectronics Laboratory, Department of Biotechnology, Delhi Technological University, Delhi 110042 (India); Dewan, Srishti [Biomedical Instrumentation Section, CSIR-National Physical Laboratory, New Delhi 110012 (India); Biomedical Engineering Department, Deenbandhu Chhotu Ram University of Science & Technology, Haryana 131039 (India); Chawla, Seema [Biomedical Engineering Department, Deenbandhu Chhotu Ram University of Science & Technology, Haryana 131039 (India); Yadav, Birendra Kumar [Rajiv Gandhi Cancer Institute and Research Centre, Rohini, Delhi 110085 (India); Sumana, Gajjala, E-mail: sumanagajjala@gmail.com [Biomedical Instrumentation Section, CSIR-National Physical Laboratory, New Delhi 110012 (India); Malhotra, Bansi Dhar, E-mail: bansi.malhotra@gmail.com [Biomedical Instrumentation Section, CSIR-National Physical Laboratory, New Delhi 110012 (India); Nanobioelectronics Laboratory, Department of Biotechnology, Delhi Technological University, Delhi 110042 (India)

2016-09-21

We report results of the studies relating to controlled deposition of the amino-functionalized silica-coated zinc oxide (Am-Si@ZnO) nano-assemblies onto an indium tin oxide (ITO) coated glass substrate using Langmuir-Blodgett (LB) technique. The monolayers have been deposited by transferring the spread solution of Am-Si@ZnO stearic acid prepared in chloroform at the air-water interface, at optimized pressure (16 mN/m), concentration (10 mg/ml) and temperature (23 °C). The high-resolution transmission electron microscopic studies of the Am-Si@ZnO nanocomposite reveal that the nanoparticles have a microscopic structure comprising of hexagonal assemblies of ZnO with typical dimensions of 30 nm. The surface morphology of the LB multilayer observed by scanning electron microscopy shows uniform surface of the Am-Si@ZnO film in the nanometer range (<80 nm). These electrodes have been utilized for chronic myelogenous leukemia (CML) detection by covalently immobilizing the amino-terminated oligonucleotide probe sequence via glutaraldehyde as a crosslinker. The response studies of these fabricated electrodes carried out using electrochemical impedance spectroscopy show that this Am-Si@ZnO LB film based nucleic acid sensor exhibits a linear response to complementary DNA (10{sup −6}–10{sup −16} M) with a detection limit of 1 × 10{sup −16} M. This fabricated platform is validated with clinical samples of CML positive patients and the results demonstrate its immense potential for clinical diagnosis. - Graphical abstract: Controlled deposition of functionalized silica coated zinc oxide nano-assemblies at the air/water interface for label free electrochemical detection of chronic myelogenous leukemia. - Highlights: • Stable and controlled deposition of Am-Si@ZnO nano-assemblies using LB technique. • Uniform monolayer deposition of the Am-Si@ZnO LB film within the nanometer range. • Am-Si@ZnO LB film shows enhanced electrochemical properties. • Fabricated

Development of pore interconnectivity/morphology in porous silica films investigated by cyclic voltammetry and slow positron annihilation spectroscopy

International Nuclear Information System (INIS)

Tang, Xiuqin; Xiong, Bangyun; Li, Qichao; Mao, Wenfeng; Xiao, Wei; Fang, Pengfei; He, Chunqing

2015-01-01

Highlights: •Porous silica films were studied by cyclic voltammetry and positron annihilation. •Highly interconnected pores were formed in the film fabricated with more CTAB. •Aligned nanochannels were observed in the porous flim prepared with 25 wt.% CTAB. •I − and Ps diffusion in the films was governed by pore interconnectivity/morphology. •Cyclic voltammetry is feasible to explore pore interconnectivity/morphology. -- Abstract: Cyclic voltammetry and positronium (Ps) 3γ-annihilation spectroscopy were applied to investigate pore interconnectivity/morphology of porous silica films fabricated with various loading of cetyltrimethyl ammonium bromide (CTAB). With increasing the ratio of CTAB up to 15 wt.%, the total charge Q, resulted from I − diffusion across the silica films, increased remarkably, indicative of formation of highly interconnected pores in the films prepared with more porogen. However, it decreased dramatically with further loading CTAB of 25 wt.%. Interestingly, 3γ-annihilation fraction I 3γ due to a triplet-state Ps (ortho-positronium, o-Ps) emission from the silica films showed a similar behavior as a function of CTAB loading. The abnormal decrement in Q and I 3γ in the film fabricated with 25 wt.% CTAB was well explained by formation of long nanochannels aligning parallel to the film surface. The results indicated that the total charge Q and Ps 3γ-annihilation fraction were closely associated with I − and Ps diffusion governed by the pore interconnectivity/morphology of the silica films, which made cyclic voltammetry possible to be a feasible tool to characterize pore interconnectivity/morphology of porous thin films

Fabrication of highly hydrophobic two-component thermosetting polyurethane surfaces with silica nanoparticles

Science.gov (United States)

Yang, Guang; Song, Jialu; Hou, Xianghui

2018-05-01

Highly hydrophobic thermosetting polyurethane (TSU) surfaces with micro-nano hierarchical structures were developed by a simple process combined with sandpaper templates and nano-silica embellishment. Sandpapers with grit sizes varying from 240 to 7000 grit were used to obtain micro-scale roughness on an intrinsic hydrophilic TSU surface. The surface wettability was investigated by contact angle measurement. It was found that the largest contact angle of the TSU surface without nanoparticles at 102 ± 3° was obtained when the template was 240-grit sandpaper and the molding progress started after 45 min curing of TSU. Silica nanoparticles modified with polydimethylsiloxane were scattered onto the surfaces of both the polymer and the template to construct the desirable nanostructures. The influences of the morphology, surface composition and the silica content on the TSU surface wettability were studied by scanning electron microscopy (SEM), attenuated total reflection (ATR) infrared (IR) spectroscopy, X-ray photoelectron spectroscopy (XPS) and contact angle measurements. The surface of the TSU/SiO2 nanocomposites containing 4 wt% silica nanoparticles exhibited a distinctive dual-scale structure and excellent hydrophobicity with the contact angle above 150°. The mechanism of wettability was also discussed by Wenzel model and Cassie-Baxter model.

Influence of p H on optical properties of nano structure sol-gel-derived silica films

International Nuclear Information System (INIS)

Heshmatpuor, F.; Adelkhani, H.; Nahavandi, M.; Noorbakhsh Shourabadi, M.

2006-01-01

Sol-gel derived silica films were fabricated by dip-coating onto glass microscope substrates. Film properties such as transmission and surface morphology were monitored as function of dip speed and sol p H. Film transmission was increased with increasing of p H in visible range. The surface morphology of films were investigated with scanning electron microscopy.

Morphology conserving aminopropyl functionalization of hollow silica nanospheres in toluene

Science.gov (United States)

Dobó, Dorina G.; Berkesi, Dániel; Kukovecz, Ákos

2017-07-01

Inorganic nanostructures containing cavities of monodisperse diameter distribution find applications in e.g. catalysis, adsorption and drug delivery. One of their possible synthesis routes is the template assisted core-shell synthesis. We synthesized hollow silica spheres around polystyrene cores by the sol-gel method. The polystyrene template was removed by heat treatment leaving behind a hollow spherical shell structure. The surface of the spheres was then modified by adding aminopropyl groups. Here we present the first experimental evidence that toluene is a suitable alternative functionalization medium for the resulting thin shells, and report the comprehensive characterization of the amino-functionalized hollow silica spheres based on scanning electron microscopy, transmission electron microscopy, N2 adsorption, FT-IR spectroscopy, Raman spectroscopy and electrokinetic potential measurement. Both the presence of the amino groups and the preservation of the hollow spherical morphology were unambiguously proven. The introduction of the amine functionality adds amphoteric character to the shell as shown by the zeta potential vs. pH function. Unlike pristine silica particles, amino-functionalized nanosphere aqueous sols can be stable at both acidic and basic conditions.

Morphology-controllable growth of GdVO4:Eu3+ nano/microstructures for an optimum red luminescence

Science.gov (United States)

Yang, Liusai; Li, Guangshe; Zhao, Minglei; Zheng, Jing; Guan, Xiangfeng; Li, Liping

2012-06-01

Chemically tailoring microstructures for an optimum red luminescence is a subject at the forefront of many disciplines, which still remains a challenge due to a poor knowledge about the roles of defects in structures. In this work, GdVO4 :Eu3+ nano/microstructures of different morphologies, including tomato-like, cookie-circle-like, and ellipsoidal-like nanoparticles, and microspheroids were synthesized via a simple hydrothermal route using trisodium citrate as a capping agent. During the growth processes, the types of vanadyl ions were adjusted by varying pH value to control the morphologies and nano/microstructures with the help of trisodium citrate. The possible mechanisms for the growth processes into diverse morphologies are presented. Further, a systematic study on defect characteristics pertinent to these diverse morphologies has been explored to achieve an optimum red luminescence. The ability is clearly shown to generate different nano/microstructures of diverse morphologies and varied defect concentrations, which provides a great opportunity for morphological control in tailoring the red luminescence property for many technological applications.

High-surface-area silica nanospheres (KCC-1) with a fibrous morphology

KAUST Repository

Polshettiwar, Vivek; Cha, Dong Kyu; Zhang, Xixiang; Basset, Jean-Marie

2010-01-01

Fibrous nanosilica: A new family of high-surface-area silica nanospheres (KCC-1) have been prepared (see picture). KCC-1 features excellent physical properties, including high surface area, unprecedented fibrous surface morphology, high thermal (up to 950 °C) and hydrothermal stabilities, and high mechanical stability. Copyright © 2010 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

High-surface-area silica nanospheres (KCC-1) with a fibrous morphology

KAUST Repository

Polshettiwar, Vivek

2010-08-02

Fibrous nanosilica: A new family of high-surface-area silica nanospheres (KCC-1) have been prepared (see picture). KCC-1 features excellent physical properties, including high surface area, unprecedented fibrous surface morphology, high thermal (up to 950 °C) and hydrothermal stabilities, and high mechanical stability. Copyright © 2010 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Fibrous nano-silica (KCC-1)-supported palladium catalyst: Suzuki coupling reactions under sustainable conditions

KAUST Repository

Fihri, Aziz; Cha, Dong Kyu; Bouhrara, Mohamed; Al Mana, Noor; Polshettiwar, Vivek

2011-01-01

Noble amines recycled: Fibrous high-surface-area nano-silica functionalized with aminopropyl groups and loaded with well-dispersed Pd nanoparticles is evaluated for the Suzuki coupling of aromatic halides. It is active for the reaction of a range of aryl bromides and iodides as well as chlorides with aryl boronic acids in good to excellent yields. The catalyst can be recovered and reused for a number of cycles with negligible loss in activity. Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Fibrous nano-silica (KCC-1)-supported palladium catalyst: Suzuki coupling reactions under sustainable conditions

KAUST Repository

Fihri, Aziz

2011-11-15

Noble amines recycled: Fibrous high-surface-area nano-silica functionalized with aminopropyl groups and loaded with well-dispersed Pd nanoparticles is evaluated for the Suzuki coupling of aromatic halides. It is active for the reaction of a range of aryl bromides and iodides as well as chlorides with aryl boronic acids in good to excellent yields. The catalyst can be recovered and reused for a number of cycles with negligible loss in activity. Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Optical and morphological properties of infrared emitting functionalized silica nanoparticles

Energy Technology Data Exchange (ETDEWEB)

Iovino, G. [Dipartimento di Fisica e Chimica, Università di Palermo, Via Archirafi 36, I-90123 Palermo (Italy); Malvindi, M.A. [Istituto Italiano di Tecnologia, Center for Bio-Molecular Nanotechnologies@Unile, Via Barsanti, Arnesano, I-73010 Lecce (Italy); Agnello, S., E-mail: simonpietro.agnello@unipa.it [Dipartimento di Fisica e Chimica, Università di Palermo, Via Archirafi 36, I-90123 Palermo (Italy); Buscarino, G.; Alessi, A. [Dipartimento di Fisica e Chimica, Università di Palermo, Via Archirafi 36, I-90123 Palermo (Italy); Pompa, P.P. [Istituto Italiano di Tecnologia, Center for Bio-Molecular Nanotechnologies@Unile, Via Barsanti, Arnesano, I-73010 Lecce (Italy); Gelardi, F.M. [Dipartimento di Fisica e Chimica, Università di Palermo, Via Archirafi 36, I-90123 Palermo (Italy)

2013-11-01

The loading process of functionalized silica nanoparticles was investigated in order to obtain nanoparticles having functional groups on their surface and Near-Infrared (NIR) emission properties. The NIR emission induced by O{sub 2} loading was studied in silica nanoparticles, produced by pyrogenic and microemulsion methods, with size ranging from 20 to 120 nm. Loading was carried out by thermal treatments in O{sub 2} atmosphere up to 400 °C and 90 bar. The effects of the thermal treatments on the NIR emission and on the structural properties were studied by luminescence and Raman techniques, whereas the morphological features were investigated by Transmission Electron Microscopy and Atomic Force Microscopy. Our data show that silica nanoparticles produced by pyrogenic technique can be loaded with O{sub 2} at lower temperature than the ones obtained by microemulsion and have a higher luminescence intensity due to the internal porosity of the latter. The treatments do not affect the nanosize of the microemulsion particles and provide NIR emitting probes of selected size. Post-processing surface functionalization of the pyrogenic nanoparticles does not affect their emission properties and provides high efficiency NIR emitters with functionalized surface. - Highlights: • Pyrogenic and microemulsion silica nanoparticles with near infrared emission. • Functionalization of nanoparticles does not change the NIR emission. • Porosity limits the emission properties of nanoparticles.

Preparation of nano-hydroxyapatite particles with different morphology and their response to highly malignant melanoma cells in vitro

Energy Technology Data Exchange (ETDEWEB)

Li Bo [National Engineering Research Center for Biomaterial, Sichuan University, Chengdu 610064 (China); Guo Bo [National Engineering Research Center for Biomaterial, Sichuan University, Chengdu 610064 (China); West China Eye Center of Huaxi Hospital, Sichuan University, Chengdu 610064 (China); Fan Hongsong [National Engineering Research Center for Biomaterial, Sichuan University, Chengdu 610064 (China)], E-mail: leewave@126.com; Zhang Xingdong [National Engineering Research Center for Biomaterial, Sichuan University, Chengdu 610064 (China)

2008-11-15

To investigate the effects of nano-hydroxyapatite (HA) particles with different morphology on highly malignant melanoma cells, three kinds of HA particles with different morphology were synthesized and co-cultured with highly malignant melanoma cells using phosphate-buffered saline (PBS) as control. A precipitation method with or without citric acid addition as surfactant was used to produce rod-like hydroxyapatite (HA) particles with nano- and micron size, respectively, and a novel oil-in-water emulsion method was employed to prepare ellipse-like nano-HA particles. Particle morphology and size distribution of the as prepared HA powders were characterized by transmission electron microscope (TEM) and dynamic light scattering technique. The nano- and micron HA particles with different morphology were co-cultured with highly malignant melanoma cells. Immunofluorescence analysis and MTT assay were employed to evaluate morphological change of nucleolus and proliferation of tumour cells, respectively. To compare the effects of HA particles on cell response, the PBS without HA particles was used as control. The experiment results indicated that particle nanoscale effect rather than particle morphology of HA was more effective for the inhibition on highly malignant melanoma cells proliferation.

Nano rough micron patterned titanium for directing osteoblast morphology and adhesion

Directory of Open Access Journals (Sweden)

Sabrina Puckett

2008-06-01

Full Text Available Sabrina Puckett, Rajesh Pareta, Thomas J WebsterDivision of Engineering, Brown University, Providence, RI, USAAbstract: Previous studies have demonstrated greater functions of osteoblasts (bone-forming cells on nanophase compared with conventional metals. Nanophase metals possess a biologically inspired nanostructured surface that mimics the dimensions of constituent components in bone, including collagen and hydroxyapatite. Not only do these components possess dimensions on the nanoscale, they are aligned in a parallel manner creating a defined orientation in bone. To date, research has yet to evaluate the effect that organized nanosurface features can have on the interaction of osteoblasts with material surfaces. Therefore, to determine if surface orientation of features can mediate osteoblast adhesion and morphology, this study investigated osteoblast function on patterned titanium substrates containing alternating regions of micron rough and nano rough surfaces prepared by novel electron beam evaporation techniques. This study was also interested in determining whether or not the size of the patterned regions had an effect on osteoblast behavior and alignment. Results indicated early controlled osteoblast alignment on these patterned materials as well as greater osteoblast adhesion on the nano rough regions of these patterned substrates. Interestingly, decreasing the width of the nano rough regions (from 80 µm to 22 µm on these patterned substrates resulted in a decreased number of osteoblasts adhering to these areas. Changes in the width of the nano rough regions also resulted in changes in osteoblast morphology, thus, suggesting there is an optimal pattern dimension that osteoblasts prefer. In summary, results of this study provided evidence that aligned nanophase metal features on the surface of titanium improved early osteoblast functions (morphology and adhesion promising for their long term functions, criteria necessary to improve

Empirical Correlation of the Morphology of Coiled Carbon Nano tubes with Their Response to Axial Compression

International Nuclear Information System (INIS)

Barber, J.R.; Boyles, J.S.; Bottomley, L.A.; Ferri, A.A.

2014-01-01

The mechanical response of thirteen different helical multi-walled carbon nano coils to axial compression is reported. Each nano coil was attached to the apex of a cantilever probe tip; its dimensions and orientation relative to the tip apex were determined with scanning electron microscopy. The atomic force microscope was employed to apply a cyclic axial load on the nano coil. Its mechanical response was determined by simultaneous collection of the thermal resonance frequency, displacement, and oscillation amplitude of the cantilever-nano tube system in real time. Depending upon compression parameters, each coil underwent buckling, bending, and slip-stick motion. Characteristic features in the thermal resonance spectrum and in the force and oscillation amplitude curves for each of these responses to induced stress are presented. Following compression studies, the structure and morphology of each nano coil were determined by transmission electron microscopy. The compression stiffness of each nano coil was estimated from the resonant frequency of the cantilever at the point of contact with the substrate surface. From this value, the elastic modulus of the nano coil was computed and correlated with the coiled carbon nano tube’s morphology.

Localization of solid micro and nano-inclusions in heterophase bioplastic blends

Science.gov (United States)

Dil, Ebrahim Jalali

Blending poly(lactic acid), PLA, with other high impact bioplastics has been introduced as an effective method for improving the toughness of PLA; however, this strategy considerably reduces the modulus and mechanical strength of PLA. The addition of solid particles is a well-known method for tuning the stiffness/toughness balance in toughened polymer matrices. Notwithstanding the significance of controlling the localization of solid inclusions in polymer blends, the literature is lacking a detailed analysis of the migration mechanisms and the effects of thermodynamic and kinetic parameters on the localization of solid particles in polymer blends. In this dissertation, the localization and migration of spherical micro- and nano-silica particles in two bioplastic blends of PLA/low density polyethylene (LDPE) and PLA/poly(butylene adipateco-terephthalate), PBAT, were studied. In the first part of this work, a detailed study on the miscibility and morphology development in the PLA/PBAT blend was carried out. The interfacial tension between PLA and PBAT was determined to be 0.6 +/- 0.15 mN/m by fitting Palierne's model on the rheological data. The miscibility of PLA/PBAT was then examined by studying the shift in the glass transition temperature (Tg) of the polymer phases at different blend compositions. The obtained results indicate a limited one-way partial miscibility of PBAT molecules in the PLA-rich phase. This partial miscibility depends significantly on the molecular weight of PBAT, which underlines its entropic nature. The morphology analysis of the blend samples revealed that the dispersed phase in PLA/PBAT blends exists in the form of fibers, even at low compositions of 1 vol.% of the dispersed phase. Finally, the co-continuity region in PLA/PBAT blends was determined using a rheological approach and it was shown that PLA/PBAT has a wide symmetric co-continuous region located between 30-40 and 60-70 vol.% of PBAT. In the second part of this project, the

Novel polyoxometalate silica nano-sized spheres: efficient catalysts for olefin oxidation and the deep desulfurization process.

Science.gov (United States)

Nogueira, Lucie S; Ribeiro, Susana; Granadeiro, Carlos M; Pereira, Eulália; Feio, Gabriel; Cunha-Silva, Luís; Balula, Salete S

2014-07-07

A novel method to prepare silica nano-sized particles incorporating polyoxometalates was developed leading to a new efficient heterogeneous oxidative catalyst. Zinc-substituted polyoxotungstate [PW11Zn(H2O)O39](5-) (PW11Zn) was encapsulated into silica nanoparticles using a cross-linked organic-inorganic core, performed through successive spontaneous reactions in water. The potassium salt of PW11Zn and the composite formed, PW11Zn-APTES@SiO2, were characterized by a myriad of solid-state methods such as FT-IR, FT-Raman, (31)P and (13)C CP/MAS solid-state NMR, elemental analysis and SEM-EDS, confirming the integrity of the PW11Zn structure immobilized in the silica nanoparticles. The new composite has shown to be a versatile catalyst for the oxidation of olefins and also to catalyze the desulfurization of a model oil using H2O2 as the oxidant and acetonitrile as the solvent. The novel composite material was capable of being recycled without significant loss of activity and maintaining its structural stability for consecutive desulfurization and olefin oxidative cycles.

Investigation of nuclear nano-morphology marker as a biomarker for cancer risk assessment using a mouse model

Science.gov (United States)

Bista, Rajan K.; Uttam, Shikhar; Hartman, Douglas J.; Qiu, Wei; Yu, Jian; Zhang, Lin; Brand, Randall E.; Liu, Yang

2012-06-01

The development of accurate and clinically applicable tools to assess cancer risk is essential to define candidates to undergo screening for early-stage cancers at a curable stage or provide a novel method to monitor chemoprevention treatments. With the use of our recently developed optical technology--spatial-domain low-coherence quantitative phase microscopy (SL-QPM), we have derived a novel optical biomarker characterized by structure-derived optical path length (OPL) properties from the cell nucleus on the standard histology and cytology specimens, which quantifies the nano-structural alterations within the cell nucleus at the nanoscale sensitivity, referred to as nano-morphology marker. The aim of this study is to evaluate the feasibility of the nuclear nano-morphology marker from histologically normal cells, extracted directly from the standard histology specimens, to detect early-stage carcinogenesis, assess cancer risk, and monitor the effect of chemopreventive treatment. We used a well-established mouse model of spontaneous carcinogenesis--ApcMin mice, which develop multiple intestinal adenomas (Min) due to a germline mutation in the adenomatous polyposis coli (Apc) gene. We found that the nuclear nano-morphology marker quantified by OPL detects the development of carcinogenesis from histologically normal intestinal epithelial cells, even at an early pre-adenomatous stage (six weeks). It also exhibits a good temporal correlation with the small intestine that parallels the development of carcinogenesis and cancer risk. To further assess its ability to monitor the efficacy of chemopreventive agents, we used an established chemopreventive agent, sulindac. The nuclear nano-morphology marker is reversed toward normal after a prolonged treatment. Therefore, our proof-of-concept study establishes the feasibility of the SL-QPM derived nuclear nano-morphology marker OPL as a promising, simple and clinically applicable biomarker for cancer risk assessment and

Uptake of silica covered Quantum Dots into living cells: Long term vitality and morphology study on hyaluronic acid biomaterials

International Nuclear Information System (INIS)

D'Amico, Michele; Fiorica, Calogero; Palumbo, Fabio Salvatore; Militello, Valeria; Leone, Maurizio; Dubertret, Benoit; Pitarresi, Giovanna; Giammona, Gaetano

2016-01-01

Quantum Dots (QDs) are promising very bright and stable fluorescent probes for optical studies in the biological field but water solubility and possible metal bio-contamination need to be addressed. In this work, a simple silica-QD hybrid system is prepared and the uptake in bovine chondrocytes living cells without any functionalization of the external protective silica shield is demonstrated. Moreover, long term treated cells vitality (up to 14 days) and the transfer of silica-QDs to the next cell generations are here reported. Confocal fluorescence microscopy was also used to determine the morphology of the so labelled cells and the relative silica-QDs distribution. Finally, we employ silica-QD stained chondrocytes to characterize, as proof of concept, hydrogels obtained from an amphiphilic derivative of hyaluronic acid (HA-EDA-C _1_8) functionalized with different amounts of the RGD peptide. - Highlights: • Non functionalized silica-quantum dots fluorescent nanoparticles uptake is observed. • Morphology studies of such cells could be done by confocal fluorescence microscopy. • Labelled chondrocytes are viable until at least 14 days. • RGD functionalized Hyaluronic Acid hydrogels are studied as cell scaffolds. • Chondrocyte are promptly attached on RGD-functionalized hydrogels.

Uptake of silica covered Quantum Dots into living cells: Long term vitality and morphology study on hyaluronic acid biomaterials

Energy Technology Data Exchange (ETDEWEB)

D' Amico, Michele [Dip. Biomedico di Medicina Interna e Specialistica, Universitá degli Studi di Palermo, Piazza delle Cliniche, 2, 90127 Palermo (Italy); Dip. di Fisica e Chimica, Universitá degli Studi di Palermo, Viale delle Scienze, Ed. 18, 90128 Palermo (Italy); Fiorica, Calogero, E-mail: calogero.fiorica@unipa.it [Dip. di Scienze e Tecnologie Molecolari e Biomolecolari, Sezione di Chimica e Tecnologie Farmaceutiche, Universitá degli Studi di Palermo, Via Archirafi, 28, 90136 Palermo (Italy); Palumbo, Fabio Salvatore [Dip. di Scienze e Tecnologie Molecolari e Biomolecolari, Sezione di Chimica e Tecnologie Farmaceutiche, Universitá degli Studi di Palermo, Via Archirafi, 28, 90136 Palermo (Italy); Militello, Valeria; Leone, Maurizio [Dip. di Fisica e Chimica, Universitá degli Studi di Palermo, Viale delle Scienze, Ed. 18, 90128 Palermo (Italy); Dubertret, Benoit [Laboratoire de Physique et d’Etude des Matèriaux, ESPCI-ParisTech, PSL Research University, Sorbonne Universitè UPMC Univ. Paris 06, CNRS, 10 rue Vauquelin, 75005 Paris (France); Pitarresi, Giovanna; Giammona, Gaetano [Dip. di Scienze e Tecnologie Molecolari e Biomolecolari, Sezione di Chimica e Tecnologie Farmaceutiche, Universitá degli Studi di Palermo, Via Archirafi, 28, 90136 Palermo (Italy)

2016-10-01

Quantum Dots (QDs) are promising very bright and stable fluorescent probes for optical studies in the biological field but water solubility and possible metal bio-contamination need to be addressed. In this work, a simple silica-QD hybrid system is prepared and the uptake in bovine chondrocytes living cells without any functionalization of the external protective silica shield is demonstrated. Moreover, long term treated cells vitality (up to 14 days) and the transfer of silica-QDs to the next cell generations are here reported. Confocal fluorescence microscopy was also used to determine the morphology of the so labelled cells and the relative silica-QDs distribution. Finally, we employ silica-QD stained chondrocytes to characterize, as proof of concept, hydrogels obtained from an amphiphilic derivative of hyaluronic acid (HA-EDA-C {sub 18}) functionalized with different amounts of the RGD peptide. - Highlights: • Non functionalized silica-quantum dots fluorescent nanoparticles uptake is observed. • Morphology studies of such cells could be done by confocal fluorescence microscopy. • Labelled chondrocytes are viable until at least 14 days. • RGD functionalized Hyaluronic Acid hydrogels are studied as cell scaffolds. • Chondrocyte are promptly attached on RGD-functionalized hydrogels.

Microwave-Assisted Combustion Synthesis of Nano Iron Oxide/Iron-Coated Activated Carbon, Anthracite, Cellulose Fiber, and Silica, with Arsenic Adsorption Studies

Directory of Open Access Journals (Sweden)

Mallikarjuna N. Nadagouda

2011-01-01

Full Text Available Combustion synthesis of iron oxide/iron coated carbons such as activated carbon, anthracite, cellulose fiber, and silica is described. The reactions were carried out in alumina crucibles using a Panasonic kitchen microwave with inverter technology, and the reaction process was completed within a few minutes. The method used no additional fuel and nitrate, which is present in the precursor itself, to drive the reaction. The obtained samples were then characterized with X-ray mapping, scanning electron microscopy (SEM, energy dispersive X-ray analysis (EDS, selected area diffraction pattern (SAED, transmission electron microscopy (TEM, X-ray diffraction (XRD, and inductively coupled plasma (ICP spectroscopy. The size of the iron oxide/iron nanoparticle-coated activated carbon, anthracite, cellulose fiber, and silica samples were found to be in the nano range (50–400 nm. The iron oxide/iron nanoparticles mostly crystallized into cubic symmetry which was confirmed by SAED. The XRD pattern indicated that iron oxide/iron nano particles existed in four major phases. That is, γ-Fe2O3, α-Fe2O3, Fe3O4, and Fe. These iron-coated activated carbon, anthracite, cellulose fiber, and silica samples were tested for arsenic adsorption through batch experiments, revealing that few samples had significant arsenic adsorption.

Hydration kinetics study of class G oil-well cement and olivine nano-silica mixtures at 20–60 °C

NARCIS (Netherlands)

Quercia Bianchi, G.; Brouwers, H.J.H.; Sobolev, K.; Shah, S.P.

2015-01-01

In this study the heat evolution of standard density slurries (1.89 g/cm3) of Class G oil-well cement and olivine nano-silica additions (0.5–2.0 % bwoc), cured under different temperatures (20–60 °C) and atmospheric pressure, were examined by isothermal calorimetry. Under isothermal and isobaric

Study of the effect of nano surface morphology on the stain-resistant property of ceramic tiles

International Nuclear Information System (INIS)

Pan, S P; Hung, J K; Liu, Y T

2014-01-01

In this study, six types of commercially available ceramic tiles, including nano-structured ceramic tiles and regular ceramic tiles, were selected to investigate the effect of surface morphology on their stain-resistant property. The stain-resistant efficiencies of various ceramic tiles with nano-size surface were measured in order to determine the appropriate method for testing ceramic tiles with nano-structure surface

Kinetically-controlled template-free synthesis of hollow silica micro-/nanostructures with unusual morphologies

International Nuclear Information System (INIS)

Zhang, An-Qi; Li, Hui-Jun; Qian, Dong-Jin; Chen, Meng

2014-01-01

We report a kinetically-controlled template-free room-temperature production of hollow silica materials with various novel morphologies, including tubes, crutches, ribbons, bundles and bells. The obtained products, which grew in a well-controlled manner, were monodispersed in shape and size. The role of ammonia, sodium citrate, polyvinylpyrrolidone, chloroauric acid and NaCl in shape control is discussed in detail. The oriented growth of these micro-/nanostructures directed by reverse micelles followed a solution–solution–solid (SSS) mechanism, similar to the classic vapor–liquid–solid mechanism. The evolution processes of silica rods, tubes, crutches, bundles and bells were recorded using transmission electron microscopy to prove the SSS mechanism. (paper)

Morphologies and wetting properties of copper film with 3D porous micro-nano hierarchical structure prepared by electrochemical deposition

International Nuclear Information System (INIS)

Wang, Hongbin; Wang, Ning; Hang, Tao; Li, Ming

2016-01-01

Highlights: • A 3D porous micro-nano hierarchical structure Cu films were prepared. • The evolution of morphology and wettability with deposition time was reported. • The effects of EDA on the microscopic morphology were revealed. • A high contact angle of 162.1° was measured when deposition time is 5 s. • The mechanism of super-hydrophobicity was illustrated by two classical models. - Abstract: Three-dimensional porous micro-nano hierarchical structure Cu films were prepared by electrochemical deposition with the Hydrogen bubble dynamic template. The morphologies of the deposited films characterized by Scanning Electronic Microscopy (SEM) exhibit a porous micro-nano hierarchical structure, which consists of three levels in different size scales, namely the honeycomb-like microstructure, the dendritic substructure and the nano particles. Besides, the factors which influenced the microscopic morphology were studied, including the deposition time and the additive Ethylene diamine. By measuring the water contact angle, the porous copper films were found to be super-hydrophobic. The maximum of the contact angles could reach as high as 162.1°. An empirical correlation between morphologies and wetting properties was revealed for the first time. The pore diameter increased simultaneously with the deposition time while the contact angle decreased. The mechanism was illustrated by two classical models. Such super-hydrophobic three-dimensional hierarchical micro-nano structure is expected to have practical application in industry.

Effects of Nano-CeO2 with Different Nanocrystal Morphologies on Cytotoxicity in HepG2 Cells

Directory of Open Access Journals (Sweden)

Lili Wang

2015-09-01

Full Text Available Cerium oxide nanoparticles (nano-CeO2 have been reported to cause damage and apoptosis in human primary hepatocytes. Here, we compared the toxicity of three types of nano-CeO2 with different nanocrystal morphologies (cube-, octahedron-, and rod-like crystals in human hepatocellular carcinoma cells (HepG2. The cells were treated with the nano-CeO2 at various concentrations (6.25, 12.5, 25, 50, 100 μg/mL. The crystal structure, size and morphology of nano-CeO2 were investigated by X-ray diffractometry and transmission electron microscopy. The specific surface area was detected using the Brunauer, Emmet and Teller method. The cellular morphological and internal structure were observed by microscopy; apoptotic alterations were measured using flow cytometry; nuclear DNA, mitochondrial membrane potential (MMP, reactive oxygen species (ROS and glutathione (GSH in HepG2 cells were measured using high content screening technology. The scavenging ability of hydroxyl free radicals and the redox properties of the nano-CeO2 were measured by square-wave voltammetry and temperature-programmed-reduction methods. All three types of nano-CeO2 entered the HepG2 cells, localized in the lysosome and cytoplasm, altered cellular shape, and caused cytotoxicity. The nano-CeO2 with smaller specific surface areas induced more apoptosis, caused an increase in MMP, ROS and GSH, and lowered the cell’s ability to scavenge hydroxyl free radicals and antioxidants. In this work, our data demonstrated that compared with cube-like and octahedron-like nano-CeO2, the rod-like nano-CeO2 has lowest toxicity to HepG2 cells owing to its larger specific surface areas.

Electrodeposition of ZnO nano-wires lattices with a controlled morphology

International Nuclear Information System (INIS)

Elias, J.; Tena-Zaera, R.; Katty, A.; Levy-Clement, C.

2006-01-01

In this work, it is shown that the electrodeposition is a changeable low cost method which allows, according to the synthesis conditions, to obtain not only plane thin layers of ZnO but different nano-structures too. In a first part, are presented the formation conditions of a compact thin layer of nanocrystalline ZnO electrodeposited on a conducing glass substrate. This layer plays a buffer layer role for the deposition of a lattice of ZnO nano-wires. The step of nano-wires nucleation is not only determined by the electrochemical parameters but by the properties of the buffer layer too as the grain sizes and its thickness. In this context, the use of an electrodeposition method in two steps allows to control the nano-wires length and diameter and their density. The morphology and the structural and optical properties of these nano-structures have been analyzed by different techniques as the scanning and transmission electron microscopy, the X-ray diffraction and the optical spectroscopy. These studies show that ZnO nano-structures are formed of monocrystalline ZnO nano-wires, presenting a great developed surface and a great optical transparency in the visible. These properties make ZnO a good material for the development of nano-structured photovoltaic cells as the extremely thin absorber cells (PV ETA) or those with dye (DSSC) which are generally prepared with porous polycrystalline TiO 2 . Its replacement by a lattice of monocrystalline ZnO nano-wires allows to reduce considerably the number of grain boundaries and in consequence to improve the transport of the electrons. The results are then promising for the PV ETA cells with ZnO nano-wires. (O.M.)

Evaluating the effect of crumb rubber and nano silica on the properties of high volume fly ash roller compacted concrete pavement using non-destructive techniques

Directory of Open Access Journals (Sweden)

Bashar S. Mohammed

2018-06-01

Full Text Available The major problems related to roller compacted concrete (RCC pavement are high rigidity, lower tensile strength which causes a tendency of cracking due to thermal or plastic shrinkage, flexural and fatigue loads. Furthermore, RCC pavement does not support the use of dowel bars or reinforcement due to the way it is placed and compacted, these also aided in cracking and consequently increased maintenance cost. To address these issues, high volume fly ash (HVFA RCC pavement was developed by partially replacing 50% cement by volume with fly ash. Crumb rubber was used as a partial replacement to fine aggregate in HVFA RCC pavement at 0%, 10%, 20%, and 30% replacement by volume. Nano silica was added at 0%, 1%, 2% and 3% by weight of cementitious materials to improve early strength development in HVFA RCC pavement and mitigate the loss of strength due to the incorporation of crumb rubber. The nondestructive technique using the rebound hammer test (RHT and ultrasonic pulse velocity (UPV were used to evaluate the effect of crumb rubber and nano silica on the performance of HVFA RCC pavement. The results showed that the use of HVFA as cement replacement decreases both the unit weight, compressive strength, rebound number (RN. Furthermore, the unit weight, compressive strength, RN, UPV and dynamic modulus of elasticity of HVFA RCC pavement all decreases with increase in crumb rubber content and increases with the addition of nano-silica. Combined UPV-RN (SonReb models for predicting the 28 days strength of HVFA RCC pavement based on combining UPV and RN were developed using multivariable regression (double power, bilinear, and double exponential models. The exponential combined SonReb model is the most suitable for predicting the compressive strength of HVFA RCC pavement using UPV and RN as the independent variable with better predicting ability, higher correlation compared to the single variable models. Keywords: Crumb rubber, High volume fly ash, Nano

Controlling pore morphology and properties of nanoporous silica films using the different architecture PS-b-P2VP as a template.

Science.gov (United States)

Yu, Yang-Yen; Chien, Wen-Chen; Chen, Shih-Ting

2010-07-01

Nanoporous silica films were prepared through the templating of amphiphilic block copolymer, poly(styrene-2-vinyl pyridine) (PS-b-P2VP), and monodispersed colloidal silica nanoparticles. The experimental and theoretical studies suggested that the intermolecular hydrogen bonding existes between the colloidal silica nanoparticles and PS-b-P2VP. The effects of the loading ratio and P2VP chain length on the morphology and properties of the prepared nanoporous silica films were investigated. TEM and AFM studies showed that the uniform pore size could be achieved and the pore size increased with increasing porogen loading. The refractive index and dielectric constant of the prepared nanoporous films decreased with an increase in PS-b-P2VP loading. On the other hand, the porosity increased with an increasing PS-b-P2VP loading. This study demonstrated a methodology to control pore morphology and properties of the nanoporous silica films through the templating of PS-b-P2VP.

Synthesis and characterization of silica mesoporous material produced by hydrothermal continues pH adjusting path way

Directory of Open Access Journals (Sweden)

A. Salemi Golezani

2016-08-01

Full Text Available Mesoporous silica molecular sieves MCM-41 were synthesized under hydrothermal conditions. For this purpose, a solution with a molar coefficient of water, cetyltri-methyl ammonium bromide surfactants as template and sodium silicate as the source of SiO2 are used. Phase formation, morphology and gas absorption properties were investigated by XRD and BET analysis, respectively. The results showed that silica mesoporous material has been successfully synthesized. A favorable special surface and porosity volume together with regular arrangement of nano metric-hexagonal porosities were obtained from this synthesis. Thickness of the wall and average diameter of the pores are 0.8 nm and 4 nm, respectively.

Nano-Crystalline Diamond Films with Pineapple-Like Morphology Grown by the DC Arcjet vapor Deposition Method

Science.gov (United States)

Li, Bin; Zhang, Qin-Jian; Shi, Yan-Chao; Li, Jia-Jun; Li, Hong; Lu, Fan-Xiu; Chen, Guang-Chao

2014-08-01

A nano-crystlline diamond film is grown by the dc arcjet chemical vapor deposition method. The film is characterized by scanning electron microscopy, high-resolution transmission electron microscopy (HRTEM), x-ray diffraction (XRD) and Raman spectra, respectively. The nanocrystalline grains are averagely with 80 nm in the size measured by XRD, and further proven by Raman and HRTEM. The observed novel morphology of the growth surface, pineapple-like morphology, is constructed by cubo-octahedral growth zones with a smooth faceted top surface and coarse side surfaces. The as-grown film possesses (100) dominant surface containing a little amorphous sp2 component, which is far different from the nano-crystalline film with the usual cauliflower-like morphology.

Surface studies on superhydrophobic and oleophobic polydimethylsiloxane-silica nanocomposite coating system

Science.gov (United States)

Basu, Bharathibai J.; Dinesh Kumar, V.; Anandan, C.

2012-11-01

Superhydrophobic and oleophobic polydimethylsiloxane (PDMS)-silica nanocomposite double layer coating was fabricated by applying a thin layer of low surface energy fluoroalkyl silane (FAS) as topcoat. The coatings exhibited WCA of 158-160° and stable oleophobic property with oil CA of 79°. The surface morphology was characterized by field emission scanning electron microscopy (FESEM) and surface chemical composition was determined by energy dispersive X-ray spectrometery (EDX) and X-ray photoelectron spectroscopy (XPS). FESEM images of the coatings showed micro-nano binary structure. The improved oleophobicity was attributed to the combined effect of low surface energy of FAS and roughness created by the random distribution of silica aggregates. This is a facile, cost-effective method to obtain superhydrophobic and oleophobic surfaces on larger area of various substrates.

Morphological classification of mesoporous silicas synthesized in a binary water-ether solvent system

NARCIS (Netherlands)

Cai, Qiang; Geng, Yi; Zhao, Xiang; Cui, Kai; Sun, Qianyao; Chen, Xihua; Feng, Qingling; Li, Hengde; Vrieling, Engel G.

2008-01-01

Using diethyl ether as a co-solvent, a non-stable interface of biphasic oil-water system (the so-called oil-water two-phase (OWTP) system) was employed in the preparation of mesostructured silicas with diversified particle morphologies. By adjusting the molar ratios of H2O:C2H5OC2H5:NH3 center dot

The size prediction of potential inclusions embedded in the sub-surface of fused silica by damage morphology

Directory of Open Access Journals (Sweden)

Gao Xiang

2017-04-01

Full Text Available A model for predicting the size ranges of different potential inclusions initiating damage on the surface of fused silica has been presented. This accounts for the heating of nanometric inclusions whose absorptivity is described based on Mie Theory. The depth profile of impurities has been measured by ICP-OES. By the measured temporal pulse profile on the surface of fused silica, the temperature and thermal stress has been calculated. Furthermore, considering the limit conditions of temperature and thermal stress strength for different damage morphologies, the size range of potential inclusions for fused silica is discussed.

Morphology control of Fe2O3 nanocrystals and their application in catalysis

International Nuclear Information System (INIS)

Liu Qiang; Cui Zhimin; Ma Zhuo; Bian Shaowei; Song Weiguo; Wan Lijun

2007-01-01

We synthesized four iron oxide catalysts with different morphologies and tested their activities in CO disproportionation. The four iron oxides were mesoporous oxide, two different sized iron oxide nano spheres and silica supported iron oxide. Hypothetical equivalent average particle size (EAPS), which was calculated from the surface area and unit cell parameter of the particles, was used to evaluate the catalytic activities of the iron oxides. A size effect (EAPS effect) was observed in these iron oxides. The CO disproportionation test results showed that silica supported iron oxide was the most active due to it having the smallest EAPS

Impact of Amorphous Silica Nanoparticles on a Living Organism: Morphological, Behavioural and Molecular Biology Implications.

Directory of Open Access Journals (Sweden)

Alfredo eAmbrosone

2014-09-01

Full Text Available It is generally accepted that silica (SiO2 is not toxic. But the increasing use of silica nanoparticles (SiO2NPs in many different industrial fields has prompted the careful investigation of its toxicity in biological systems. In this report, we describe the effects elicited by SiO2NPs on animal and cell physiology. Stable and monodisperse amorphous silica nanoparticles 25nm in diameter, were administered to living Hydra vulgaris (Cnidaria. The dose-related effects were defined by morphological and behavioural assays. The results revealed an all-or-nothing lethal toxicity with a rather high threshold (35nM NPs and a LT50 of 38h. At sub lethal doses the morpho-physiological effects included: animal morphology alterations, paralysis of the gastric region, disorganization and depletion of tentacle specialized cells, increase of apoptotic and collapsed cells and reduction of the epithelial cell proliferation rate. Transcriptome analysis (RNAseq revealed 45 differentially expressed genes, mostly involved in stress response and cuticle renovation. Our results show that Hydra reacts to SiO2NPs, is able to rebalance the animal homeostasis up to a relatively high doses of SiO2NPs and that the physiological modifications are transduced to gene expression modulation.

Gold nano-particles fixed on glass

International Nuclear Information System (INIS)

Worsch, Christian; Wisniewski, Wolfgang; Kracker, Michael; Rüssel, Christian

2012-01-01

Highlights: ► We produced wear resistant gold–ruby coatings on amorphous substrates. ► Thin sputtered gold layers were covered by or embedded in silica coatings. ► Annealing above T g of the substrate glass led to the formation of gold nano particles. ► A 1 1 1-texture of the gold particles is observed via XRD and EBSD. ► EBSD-patterns can be acquired from crystals covered by a thin layer of glass. - Abstract: A simple process for producing wear resistant gold nano-particle coatings on transparent substrates is proposed. Soda-lime-silica glasses were sputtered with gold and subsequently coated with SiO 2 using a combustion chemical vapor deposition technique. Some samples were first coated with silica, sputtered with gold and then coated with a second layer of silica. The samples were annealed for 20 min at either 550 or 600 °C. This resulted in the formation of round, well separated gold nano-particles with sizes from 15 to 200 nm. The color of the coated glass was equivalent to that of gold–ruby glasses. Silica/gold/silica coatings annealed at 600 °C for 20 min were strongly adherent and scratch resistant. X-ray diffraction and electron backscatter diffraction (EBSD) were used to describe the crystal orientations of the embedded particles. The gold particles are preferably oriented with their (1 1 1) planes perpendicular to the surface.

The potential use of silica sand as nanomaterials for mortar

Science.gov (United States)

Setiati, N. Retno

2017-11-01

The development of nanotechnology is currently experiencing rapid growth. The use of the term nanotechnology is widely applied in areas such as healthcare, industrial, pharmaceutical, informatics, or construction. By the nanotechnology in the field of concrete construction, especially the mechanical properties of concrete are expected to be better than conventional concrete. This study aims to determine the effect of the potential of silica sand as a nanomaterial that is added into the concrete mix The methodology used consist of nanomaterial synthesis process of silica sand using Liquid Polishing Milling Technology (PLMT). The XRF and XRD testing were conducted to determine the composition of silica contained in the silica sand and the level of reactivity of the compound when added into the concrete mix. To determine the effect of nano silica on mortar, then made the specimen with size 50 mm x 50 mm x 50 mm. The composition of mortar is made in two variations, ie by the addition of 3% nano silica and without the addition of nanosilica. To know the mechanical properties of mortar, it is done testing of mortar compressive strength at the age of 28 days. Based on the analysis and evaluation, it is shown that compounds of silica sand in Indonesia, especially Papua reached more than 99% SiO2 and so that the amorphous character of silica sand can be used as a nanomaterial for concrete construction. The results of mechanical tests show that there is an increase of 12% compressive strength of mortar that is added with 3% nano silica.

Preparation and Characterization of Hybrid Nanocomposite of Polyacrylamide/Silica-Nanoparticles

Directory of Open Access Journals (Sweden)

Ahmad Rabiee

2013-01-01

Full Text Available Polyacrylamides are water soluble macromolecules. These polymers are widely used for flocculation, separation and treatment of solid-liquid phase materials. In this research, organic-inorganic hybrid of polyacrylamide/silica nanoparticle is prepared via radical polymerization. First, the silica nanoparticle surfaces were modified by 3-methacryloxypropyltrimethoxysilane as coupling agent using a sol-gel technique in aqueous media in acidic condition. Afterwards, the modified nanoparticles are copolymerized by acrylamide monomer in presence of a peroxide initiator during a free radical polymerization. The chemical structure of the prepared modified nano-silica as well as polyacrylamide nanocomposite was studied and confirmed by FTIR spectroscopy technique. The morphology of nanocomposite was investigated by scanning electron microscopy. The SEM micrograph showed that the surface of the composite did not display any phase separation. Nanoparticles distribution was investigated by SEM-EDX technique. The results showed a uniform distribution of particles throughout the polymer bulk. TEM analysis showed the presence of silica nanoparticles in bulk of polymer which is an indicative of suitable dispersion of nanoparticles. The thermal stability of hybrid nanocomosite with that of polyacrylamide was compared by TGA technique. The higher thermal stability of hybrid nanocomposite with respect to homopolymer is indicative of a reaction between the modified nanoparticles and polyacrylamide chain. The presence of silica particles in copolymer was also confirmed with EDX analysis in ash content of hybrid nanocomposite.

Integrated lithography to prepare periodic arrays of nano-objects

International Nuclear Information System (INIS)

Sipos, Áron; Szalai, Anikó; Csete, Mária

2013-01-01

We present an integrated lithography method to prepare versatile nano-objects with variable shape and nano-scaled substructure, in wavelength-scaled periodic arrays with arbitrary symmetry. The idea is to illuminate colloid sphere monolayers by polarized beams possessing periodic lateral intensity modulations. Finite element method was applied to determine the effects of the wavelength, polarization and angle of incidence of the incoming beam, and to predict the characteristics of nano-objects, which can be fabricated on thin metal layer covered substrates due to the near-field enhancement under silica colloid spheres. The inter-object distance is controlled by varying the relative orientation of the periodic intensity modulation with respect to the silica colloid sphere monolayer. It is shown that illuminating silica colloid sphere monolayers by two interfering beams, linear patterns made of elliptical holes appear in case of linear polarization, while circularly polarized beams result in co-existent rounded objects, as more circular nano-holes and nano-crescents. The size of the nano-objects and their sub-structure is determined by the spheres diameter and by the wavelength. We present various complex plasmonic patterns made of versatile nano-objects that can be uniquely fabricated applying the inherent symmetry breaking possibilities in the integrated lithography method.

Effect of morphology and solvent on two-photon absorption of nano zinc oxide

Energy Technology Data Exchange (ETDEWEB)

Kavitha, M.K. [Department of Chemistry, Indian Institute of Space Science and Technology, Valiamala, Thiruvananthapuram 695547, Kerala (India); Haripadmam, P.C.; Gopinath, Pramod; Krishnan, Bindu [Department of Physics, Indian Institute of Space Science and Technology, Valiamala, Thiruvananthapuram 695547, Kerala (India); John, Honey, E-mail: honey@iist.ac.in [Department of Chemistry, Indian Institute of Space Science and Technology, Valiamala, Thiruvananthapuram 695547, Kerala (India)

2013-05-15

Highlights: ► ZnO nanospheres and triangular structures synthesis by novel precipitation technique. ► The effect of precursor concentration on the size and shape of nano ZnO. ► Open aperture Z-scan measurements of the ZnO nanoparticle dispersions. ► Nanospheres exhibit higher two photon absorption coefficient than triangular nanostructures. ► Nanospheres dispersed in water exhibit higher two photon absorption coefficient than its dispersion in 2-propanol. - Abstract: In this paper, we report the effect of morphology and solvent on the two-photon absorption of nano zinc oxide. Zinc oxide nanoparticles in two different morphologies like nanospheres and triangular nanostructures are synthesized by novel precipitation technique and their two-photon absorption coefficient is measured using open aperture Z-scan technique. Experimental results show that the zinc oxide nanospheres exhibit higher two-photon absorption coefficient than the zinc oxide triangular nanostructures. The zinc oxide nanospheres dispersed in water exhibit higher two-photon absorption coefficient than that of its dispersion in 2-propanol. The zinc oxide nanospheres dispersed in water shows a decrease in two-photon absorption coefficient with an increase in on-axis irradiance. The result confirms the dependence of shape and solvent on the two-photon absorption of nano zinc oxide.

Thermal Properties, Structure and Morphology of Graphene Reinforced Polyethylene Terephthalate/ Polypropylene Nano composites

International Nuclear Information System (INIS)

Inuwa, I.M.; Hassan, A.; Shamsudin, S.A.

2014-01-01

In this work the thermal properties, structure and morphology of a blend of polyethylene terephthalate (PET) and polypropylene (PP) reinforced with graphene nano platelets (GNP) were investigated. A blend of PET/ PP (70/ 30 weight percent) compatibilized with styrene-ethylene-butylene-styrene grafted maleic anhydride triblock copolymer (10 phr) were fabricated by melt extrusion process in a twin screw extruder. The effective thermal conductivity of the nano composites increased as a function of the GNP concentration. More than 80 % increase in effective thermal conductivity was observed for the 7 phr reinforced sample compared to the neat blend. This observation was attributed to the development interconnected GNP sheets which formed heat conductive bridges that are suitable for maximum heat transfer. However, in the case of thermal stability which is a function of dispersibility of GNP in polymer matrix, the maximum increase was observed at 3 phr GNP loading which could be attributed to the uniform dispersion of GNPs in the matrix. It is explained that the GNP nano fillers migrated to the surface of matrix forming an effective oxygen barrier due to char formation. Morphological studies revealed uniform dispersion graphene in the polymer matrix at 3 phr GNP loading along with isolated instances of exfoliation of the graphene layers. (author)

Morphological and textural characterization of functionalized particulate silica xerogels

Science.gov (United States)

de Miranda, Lazaro A.; Mohallem, Nelcy D. S.; de Magalhães, Welington F.

2006-03-01

The functionalization of xerogels for use in chromatography and catalysis was carried out by solubilization of amorphous silica using a soxhlet extractor. Xerogels were prepared by sol-gel method using tetraethoxysilane, TEOS, ethanol, and water in a 1/3/10 molar ratio with HCl and HF as catalysts. The samples were prepared in monolithic form and dried at 70 °C and 550 °C for 1 h each. After functionalization, changes in textural and morphological characteristics of xerogels were investigated by means of nitrogen gas adsorption, positron annihilation lifetime spectroscopy (PALS), and scanning electron microscopy (SEM). As the analysis methods are based on different physical principles, the results are complementary, leading to a good knowledge of the texture of the samples studied.

Morphological and textural characterization of functionalized particulate silica xerogels

International Nuclear Information System (INIS)

Miranda, Lazaro A. de; Mohallem, Nelcy D.S.; Magalhaes, Welington F. de

2006-01-01

The functionalization of xerogels for use in chromatography and catalysis was carried out by solubilization of amorphous silica using a soxhlet extractor. Xerogels were prepared by sol-gel method using tetraethoxysilane, TEOS, ethanol, and water in a 1/3/10 molar ratio with HCl and HF as catalysts. The samples were prepared in monolithic form and dried at 70 deg. C and 550 deg. C for 1 h each. After functionalization, changes in textural and morphological characteristics of xerogels were investigated by means of nitrogen gas adsorption, positron annihilation lifetime spectroscopy (PALS), and scanning electron microscopy (SEM). As the analysis methods are based on different physical principles, the results are complementary, leading to a good knowledge of the texture of the samples studied

Fabrication of semi-transparent super-hydrophobic surface based on silica hierarchical structures

KAUST Repository

Chen, Ping-Hei

2011-01-01

This study successfully develops a versatile method of producing superhydrophobic surfaces with micro/nano-silica hierarchical structures on glass surfaces. Optically transparent super hydrophobic silica thin films were prepared by spin-coating silica particles suspended in a precursor solution of silane, ethanol, and H2O with molar ratio of 1:4:4. The resulting super hydrophobic films were characterized by scanning electron microscopy (SEM), optical transmission, and contact angle measurements. The glass substrates in this study were modified with different particles: micro-silica particles, nano-silica particles, and hierarchical structures. This study includes SEM micrographs of the modified glass surfaces with hierarchical structures at different magnifications. © 2011 The Korean Society of Mechanical Engineers and Springer-Verlag Berlin Heidelberg.

Hybrid Nano composite Membranes for PEMFC Applications

International Nuclear Information System (INIS)

Niepceron, F.

2008-03-01

This work aims at validating a new concept of hybrid materials for the realization of proton exchange membranes, an essential constituent of PEM fuel cells. The originality of this nano-composite hybrid concept corresponds to a separation of the membrane's properties. We investigated the preparation of composite materials based on an inert, relatively low cost, polymer matrix (PVDF-HFP) providing the mechanical stability embedding inorganic fillers providing the necessary properties o f proton-conduction and water retention. The first step of this work consisted in the modification of fumed silica to obtain a proton-conducting filler. An ionic exchange capacity (CEI) equal to 3 meq/g was obtained by the original grafting of sodium poly(styrene-sulfonate) chains from the surface of particles. Nano-composite hybrid membranes PVDF-HFP/functionalized silica were accomplished by a film casting process. The coupling of the morphological and physicochemical analyses validated the percolation of the inorganic phase for 30 wt.% of particles. Beyond 40 % of loading, measured protonic conductivity is higher than the reference membrane Nafion 112. Finally, these membranes presented high performances, above 0.8 W/cm 2 , in single-cell fuel cell tests. A compromise is necessary according to the rate of loading between performances in fuel cell and mechanical properties of the membrane. 50 % appeared as best choice with, until 90 C, a remarkable thermal stability of the performances. (author)

Thermostability and surface morphology of nano- and micro-filled NBR/CSM and CR/CSM rubber blends

Directory of Open Access Journals (Sweden)

M. MARINOVIC-CINCOVIC

2004-02-01

Full Text Available Acrylonitrile-butadiene rubber (NBR, polychloroprene rubber (CR, chlorosulphonated polyethylene rubber (CSM and their blends were cross-linked with sulphur, ethylene-thiourea, magnesium oxide or their combination. The effect of nano- and micro- particle sized of 35 pphr SiO2 on the thermostability and surface morphology of all the crosslinked systems was investigated. Identification of the structure of nano- and micro- particle sized SiO2 filled NBR/CSM and CR/CSM crosslinked systems was carried out by Fourier transform infrared spectroscopy (FTIR with an attenuated total reflectance (ATR extension. The thermal stability of the nano- and micro- particle sized SiO2 filled NBR/CSM and CR/CSM crosslinked systems were carried out by thermogravimetric analysis (TGA. The glass transition temperature (Tg of the samples was determined by differential scanning calorimetry (DSC. The morphology of the fracture surface of the crosslinked systems was carried out by scanning electron microscope (SEM. The results show when filled with nano-particle sized of SiO2 NBR/CSM and CR/CSM polymer matrix have a strong peak from SiO–C at 1079 cm-1. This suggests the an interaction between the SiO2, which should lead to an increased thermal stability, higher values of Tg, better dispersion the nano-SiO2 and more polish, without cracks than micro-filled NBR/CSM and CR/CSM crosslinked systems.

Impact of silica dioxide nanoparticles on the morphology of internal organs in rats by oral supplementation

Directory of Open Access Journals (Sweden)

N.V. Zaitseva

2016-12-01

Full Text Available The object of the study was amorphous silica dioxide (SiO 2 , which is widely used as a food additive (E551, a subsidiary component in pharmaceutical preparations, perfumery and cosmetic products etc. In the specification of JECFA silica dioxide does not have information about the size of its particles, which allows the use of fine amorphous SiO 2 , obtained by gas phase hydrolysis of tetrachlorosilane as a food additive. This material, known as the "Aerosil", is characterized by the size of the specific surface area of 300–380 m 2 /g and the size of its relatively weakly agglomerated particles of 6–30 nm, i.e., it is a nanomaterial. In the biological model the morphological changes in organs and tissue systems on oral supplementation of nanoscale particles of silica dioxide were studied. Wistar male rats were given nanosized silica dioxide with specific surface area of 300 m 2 /g and primary nanoparticle size on the basis of data of electrical, atomic-powered microscopy, and dynamic light scattering in the range of 20–60 nm during 92 days. Light microscopic morphological examination of organs of rats showed a relatively mild inflammation in the structure of parenchymal organs (liver, kidney, not showing a certain dose-dependent nanoparticles. The most pronounced changes were in ileum morphology, consisting of a massive lymph macrophage and eosinophil infiltration of villi, without any apparent violation of their epithelial layer structure, which indirectly indicates the absence of violations of the barrier function of the intestinal epithelium. At the maximum dose of 100 mg/kg bw, the increased immune response was the most significant in the wall of the ileum. The results indicate the potential risks to human health when using SiO 2 having a specific surface area of 300 m 2 /g or higher in the composition of food products as a food additive.

Self-cleaning behavior in polyurethane/silica coatings via formation of a hierarchical packed morphology of nanoparticles

Energy Technology Data Exchange (ETDEWEB)

Hejazi, Iman [Department of Polymer Engineering & Color Technology, Amirkabir University of Technology, P.O. Box 15875/4413, Tehran (Iran, Islamic Republic of); Mir Mohamad Sadeghi, Gity, E-mail: Gsadeghi@aut.ac.ir [Department of Polymer Engineering & Color Technology, Amirkabir University of Technology, P.O. Box 15875/4413, Tehran (Iran, Islamic Republic of); Seyfi, Javad [Department of Chemical Engineering, Shahrood Branch, Islamic Azad University, P.O. Box 36155-163, Shahrood (Iran, Islamic Republic of); Jafari, Seyed-Hassan [School of Chemical Engineering, University of Tehran, P.O. Box 11155-4563, Tehran (Iran, Islamic Republic of); Khonakdar, Hossein Ali [Iran Polymer and Petrochemical Institute, P.O. Box 14965/115, Tehran (Iran, Islamic Republic of)

2016-04-15

Graphical abstract: - Highlights: • Self-cleaning behavior was imparted to the hydrophilic polyurethane. • A hierarchical packed morphology is responsible for the superhydrophobicity. • Prolonged pressing process cannot lead to superhydrophobicity due to migration of TPU. • Samples exhibited excellent stability against media with a wide range of pH values. - Abstract: In the current research, a hierarchical morphology comprising of packed assembly of nanoparticles was induced in thermoplastic polyurethane (TPU)/silica nanocomposite coatings in order to achieve self-cleaning behavior. Moderately hydrophilic behavior of TPU hinders its transforming to a superhydrophobic material. In the presented method, a very thin layer of silica nanoparticles is applied to the surface of TPU sheets under elevated temperature and pressure. As temperature and pressure of the process remain unchanged, processing time was considered as a main variable. Based on scanning electron microscopy and confocal microscopy results, it was found that at a certain processing time, nanoparticles can form an utterly packed morphology leading to a self-cleaning behavior. Once the process was prolonged, TPU macromolecules found the chance to migrate onto the coating's top layer due to the enhanced mobility of chains at high temperature. This observation was further proved by X-ray photoelectron spectroscopy analysis and cross-sectional morphology. The presented method has promising potentials in transforming intrinsically hydrophilic polymers into superhydrophobic materials with self-cleaning behavior.

Optical Properties and Surface Morphology of Nano-composite PMMA: TiO2 Thin Films

International Nuclear Information System (INIS)

Lyly Nyl Ismail; Ahmad Fairoz Aziz; Habibah Zulkefle

2011-01-01

There are two nano-composite PMMA: TiO 2 solutions were prepared in this research. First solution is nano-composite PMMA commercially available TiO 2 nanopowder and the second solution is nano-composite PMMA with self-prepared TiO 2 powder. The self-prepared TiO 2 powder is obtained by preparing the TiO 2 sol-gel. Solvo thermal method were used to dry the TiO 2 sol-gel and obtained TiO 2 crystal. Ball millers were used to grind the TiO 2 crystal in order to obtained nano sized powder. Triton-X was used as surfactant to stabilizer the composite between PMMA: TiO 2 . Besides comparing the nano-composite solution, we also studied the effect of the thin films thickness on the optical properties and surface morphology of the thin films. The thin films were deposited by sol-gel spin coating method on glass substrates. The optical properties and surface characterization were measured with UV-VIS spectrometer equipment and atomic force microscopy (AFM). The result showed that nano-composite PMMA with self prepared TiO 2 give high optical transparency than nano-composite PMMA with commercially available TiO 2 nano powder. The results also indicate as the thickness is increased the optical transparency are decreased. Both AFM images showed that the agglomerations of TiO 2 particles are occurred on the thin films and the surface roughness is increased when the thickness is increased. High agglomeration particles exist in the AFM images for nano-composite PMMA: TiO 2 with TiO 2 nano powder compare to the other nano-composite solution. (author)

The efficiency of biosynthesis silica nanoparticles at removal of heavy metals Cr and Cu from aqueous solutions

Directory of Open Access Journals (Sweden)

Mohammad Hossein Sayadi

2017-05-01

Full Text Available Background and Aim: Nanotechnology considered as one of the main management strategy in reducing negative effects of water pollution, which leads to treating of water inexpensive and more effective. This study aimed to investigate the removal of Cr and Cu from aqueous solutions using nano-silicate which is synthesized by rice husk. Materials and Methods: In the present study, functionalized nano-silica with rice husk was fabricated and characterized by FT-IR، TEM, SEM and XRD. The effect of adsorbent dosage, initial concentration and equilibrium of chromium and copper and contact time in removal of mentioned heavy metals were investigated. Finally, the adsorption isotherms were analyzed. Results: The silica nanoparticles had nearly spherical morphology with a uniform size of about 80 nm. However, the obtained functionalized silica nanoparticles were spherical (about 90 nm in diameter. Results showed that optimum adsorption of Cr and Cu contaminant obtained at 100 minutes, while the optimum amount of adsorbent for Cr and Cu were 125 and 100 mg respectively. The optimal concentration of Cr and Cu was 2 mg/l. The correlation coefficients of adsorption isotherms of Cr (R2Langmuir =0.9946 and Cu (R2Langmuir =0.999 showed the good agreement between the adsorption data and Langmuir model. Conclusion: The study showed that the silica nanoparticles can be produced using agricultural waste as a inexpensive and environmentally friendly method and can be used to removing of contaminants from the aquatic environment.

Porous silica nanoparticles as carrier for curcumin delivery

Science.gov (United States)

Hartono, Sandy Budi; Hadisoewignyo, Lannie; Irawaty, Wenny; Trisna, Luciana; Wijaya, Robby

2018-04-01

Mesoporous silica nanoparticles (MSN) with large surface areas and pore volumes show great potential as drug and gene carriers. However, there are still some challenging issues hinders their clinical application. Many types of research in the use of mesoporous silica material for drug and gene delivery involving complex and rigorous procedures. A facile and reproducible procedure to prepare combined drug carrier is required. We investigated the effect of physiochemical parameters of mesoporous silica, including structural symmetry (cubic and hexagonal), particles size (micro size: 1-2 µm and nano size: 100 -300 nm), on the solubility and release profile of curcumin. Transmission Electron Microscopy, X-Ray Powder Diffraction, and Nitrogen sorption were used to confirm the synthesis of the mesoporous silica materials. Mesoporous silica materials with different mesostructures and size have been synthesized successfully. Curcumin has anti-oxidant, anti-inflammation and anti-virus properties which are beneficial to fight various diseases such as diabetic, cancer, allergic, arthritis and Alzheimer. Curcumin has low solubility which minimizes its therapeutic effect. The use of nanoporous material to carry and release the loaded molecules is expected to enhance curcumin solubility. Mesoporous silica materials with a cubic mesostructure had a higher release profile and curcumin solubility, while mesoporous silica materials with a particle size in the range of nano meter (100-300) nm also show better release profile and solubility.

The influence of chain rigidity and the degree of sulfonation on the morphology of block copolymers as nano reactor

Science.gov (United States)

Hong, K.; Zhang, X.

2005-03-01

Polyelectrolyte block copolymer was used to form an ordered domain of ionic block as a ``nanoreactor'' due to its ability to bind oppositely charged metal ion, Zn^2+, Fe^2+ etc. The purpose of our research is to investigate the controllability of the size and morphology of domains (inorganic nano particles) by changing backbone stiffness, the charge density and the volume fraction of ionic block. Poly(styrene sulfonate) (PSS), which backbone is flexible, and poly(cyclohexadiene sulfonate) (PCHDS), which backbone is ``semiflexible'', were used as ionic blocks. We synthesized PtBS-PSS and PS-PCHDS with various degree of sulfonation and the volume fraction. Zinc oxide (ZnO) nano particles successfully formed in the ionic domain of microphase separated block copolymers. We used SANS to characterize the morphology of block copolymers and TEM for block copolymer containing ZnO nano particles. Our experimental results show that the chemistry of ``sulfonation'' of block copolymers can be successfully used to synthesize nano composite materials.

Synthesis of Boron Nano wires, Nano tubes, and Nano sheets

International Nuclear Information System (INIS)

Patel, R.B.; Chou, T.; Iqbal, Z.

2014-01-01

The synthesis of boron nano wires, nano tubes, and nano sheets using a thermal vapor deposition process is reported. This work confirms previous research and provides a new method capable of synthesizing boron nano materials. The materials were made by using various combinations of MgB 2 , Mg(BH 4 ) 2 , MCM-41, NiB, and Fe wire. Unlike previously reported methods, a nanoparticle catalyst and a silicate substrate are not required for synthesis. Two types of boron nano wires, boron nano tubes, and boron nano sheets were made. Their morphology and chemical composition were determined through the use of scanning electron microscopy, transmission electron microscopy, and electron energy loss spectroscopy. These boron-based materials have potential for electronic and hydrogen storage applications.

Co-Assembled Supported Catalysts: Synthesis of Nano-Structured Supported Catalysts with Hierarchic Pores through Combined Flow and Radiation Induced Co-Assembled Nano-Reactors

Directory of Open Access Journals (Sweden)

Galip Akay

2016-05-01

Full Text Available A novel generic method of silica supported catalyst system generation from a fluid state is presented. The technique is based on the combined flow and radiation (such as microwave, thermal or UV induced co-assembly of the support and catalyst precursors forming nano-reactors, followed by catalyst precursor decomposition. The transformation from the precursor to supported catalyst oxide state can be controlled from a few seconds to several minutes. The resulting nano-structured micro-porous silica supported catalyst system has a surface area approaching 300 m2/g and X-ray Diffraction (XRD-based catalyst size controlled in the range of 1–10 nm in which the catalyst structure appears as lamellar sheets sandwiched between the catalyst support. These catalyst characteristics are dependent primarily on the processing history as well as the catalyst (Fe, Co and Ni studied when the catalyst/support molar ratio is typically 0.1–2. In addition, Ca, Mn and Cu were used as co-catalysts with Fe and Co in the evaluation of the mechanism of catalyst generation. Based on extensive XRD, Scanning Electron Microscopy (SEM and Transmission Electron Microscopy (TEM studies, the micro- and nano-structure of the catalyst system were evaluated. It was found that the catalyst and silica support form extensive 0.6–2 nm thick lamellar sheets of 10–100 nm planar dimensions. In these lamellae, the alternate silica support and catalyst layer appear in the form of a bar-code structure. When these lamellae structures pack, they form the walls of a micro-porous catalyst system which typically has a density of 0.2 g/cm3. A tentative mechanism of catalyst nano-structure formation is provided based on the rheology and fluid mechanics of the catalyst/support precursor fluid as well as co-assembly nano-reactor formation during processing. In order to achieve these structures and characteristics, catalyst support must be in the form of silane coated silica nano

Facile fabrication of nano-structured silica hybrid film with superhydrophobicity by one-step VAFS approach

Science.gov (United States)

Jia, Yi; Yue, Renliang; Liu, Gang; Yang, Jie; Ni, Yong; Wu, Xiaofeng; Chen, Yunfa

2013-01-01

Here we report a novel one-step vapor-fed aerosol flame synthesis (VAFS) method to attain silica hybrid film with superhydrophobicity on normal glass and other engineering material substrates using hexamethyldisiloxane (HMDSO) as precursor. The deposited nano-structured silica films represent excellent superhydrophobicity with contact angle larger than 150° and sliding angle below 5°, without any surface modification or other post treatments. SEM photographs proved that flame-made SiO2 nanoparticles formed dual-scale surface roughness on the substrates. It was confirmed by FTIR and XPS that the in situ formed organic fragments on the particle surface as species like (CH3)xSiO2-x/2 (x = 1, 2, 3) which progressively lowered the surface energy of fabricated films. Thus, these combined dual-scale roughness and lowered surface energy cooperatively produced superhydrophobic films. IR camera had been used to monitor the real-time flame temperature. It is found that the inert dilution gas inflow played a critical role in attaining superhydrophobicity due to its cooling and anti-oxidation effect. This method is facile and scalable for diverse substrates, without any requirement of complex equipments and multiple processing steps. It may contribute to the industrial fabrication of superhydrophobic films.

Hydrophobic silica nanoparticles as reinforcing filler for poly (lactic acid polymer matrix

Directory of Open Access Journals (Sweden)

Pilić Branka M.

2016-01-01

Full Text Available Properties of poly (lactic acid (PLA and its nanocomposites, with silica nanoparticles (SiO2, as filler were investigated. Neat PLA films and PLA films with different percentage of hydrophobic fumed silica nanoparticles (0.2, 0.5, 1, 2, 3 and 5 wt. % were prepared by solution casting method. Several tools were used to characterize the influence of different silica content on crystalline behavior, and thermal, mechanical and barrier properties of PLA/SiO2 nanocomposites. Results from scanning electron microscope (SEM showed that the nanocomposite preparation and selection of specific hydrophobic spherical nano filler provide a good dispersion of the silica nanoparticles in the PLA matrix. Addition of silica nanoparticles improved mechanical properties, the most significant improvement being observed for lowest silica content (0.2wt.%. Barrier properties were improved for all measured gases at all loadings of silica nanoparticles. The degree of crystallinity for PLA slightly increased by adding 0.2 and 0.5 wt. % of nano filler. [Projekat Ministarstva nauke Republike Srbije, br. III46001

Nanoscale assembly of lanthanum silica with dense and porous interfacial structures.

Science.gov (United States)

Ballinger, Benjamin; Motuzas, Julius; Miller, Christopher R; Smart, Simon; Diniz da Costa, João C

2015-02-03

This work reports on the nanoscale assembly of hybrid lanthanum oxide and silica structures, which form patterns of interfacial dense and porous networks. It was found that increasing the molar ratio of lanthanum nitrate to tetraethyl orthosilicate (TEOS) in an acid catalysed sol-gel process alters the expected microporous metal oxide silica structure to a predominantly mesoporous structure above a critical lanthanum concentration. This change manifests itself by the formation of a lanthanum silicate phase, which results from the reaction of lanthanum oxide nanoparticles with the silica matrix. This process converts the microporous silica into the denser silicate phase. Above a lanthanum to silica ratio of 0.15, the combination of growth and microporous silica consumption results in the formation of nanoscale hybrid lanthanum oxides, with the inter-nano-domain spacing forming mesoporous volume. As the size of these nano-domains increases with concentration, so does the mesoporous volume. The absence of lanthanum hydroxide (La(OH)3) suggests the formation of La2O3 surrounded by lanthanum silicate.

Nano-scale observations of interface between lichen and basaltic rock: Pseudomorphic growth of amorphous silica on augite

Science.gov (United States)

Tamura, T.; Kyono, A.; Kebukawa, Y.; Takagi, S.

2017-12-01

Recently, lichens as the earliest colonizers of terrestrial habitats are recognized to accelerate the mineral degradation at the interface between lichens and surface rocks. Much interest has been therefore devoted in recent years to the weathering induced by the lichen colonization. Here, we report nano-scale observations of the interface between lichens and basaltic rock by TEM and STXM techniques. Some samples of basaltic rocks totally covered by lichens were collected from the 1986 lava flows on the northwest part of Izu-Oshima volcano, Japan. To prepare specimens for the nano-scale observation, we utilized the focused ion beam (FIB) system. The microstructure and local chemistry of the specimens were thoroughly investigated by TEM equipped with energy-dispersive X-ray spectroscopy (EDX). Chemical components and chemical heterogeneity at the interface were observed by scanning transmission X-ray microscopy (STXM) at Advanced Light Source branch line 5.3.2.2. The collected rocks were classified into the augite-pigeonite-bronzite basalt including 6 to 8% plagioclase phenocrysts. The lichens adhering to the rocks were mainly Stereocaulon vesuvianum, fruticose lichen, which are widespread over the study area. The metabolites of the Stereocaulon vesuvianum exhibited a mean pH of 4.5 and dominance by acids. The STEM-EDX observations revealed that the interface between augite and the lichen was completely covered with amorphous silica multilayer with a thickness of less than 1 µm. Ca L-edge XANES spectra of the augite showed that the energy profile of the absorption edge at 349 eV was varied with the depth from the surface, indicating that the M2 site coordination accommodating Ca2+ undergoes significant change in shape as a function of distance from the surface. This behavior results from the fact that the M2 site is more distorted and more flexible in the C2/c clinopyroxene phase. Taking into consideration that the S. vesuvianum can produce acidic organic compounds

The influence of mannitol on morphology and disintegration of spray-dried nano-embedded microparticles.

Science.gov (United States)

Torge, Afra; Grützmacher, Philipp; Mücklich, Frank; Schneider, Marc

2017-06-15

Nano-embedded microparticles represent a promising approach to deliver nanoparticles to the lungs. Microparticles with an appropriate aerodynamic diameter enable an application by dry powder inhaler and the transport of nanoparticles into the airways. By disintegration after deposition, nanoparticles can be released to exhibit their advantages such as a sustained drug release and delivery of the drug across the mucus barrier. The use of an appropriate matrix excipient to embed the nanoparticles is essential for the necessary disintegration and release of nanoparticles. In this context we investigated the influence of mannitol on the morphology, aerodynamic properties and disintegration behavior of nano-embedded microparticles. PLGA nanoparticles and mannitol were spray dried each as sole component and in combination in three different ratios. An influence of the mannitol content on the morphology was observed. Pure mannitol microparticles were solid and spherical, while the addition of nanoparticles resulted in raisin-shaped hollow particles. The different morphologies can be explained by diffusion processes of the compounds described by the Péclet-number. All powders showed suitable aerodynamic properties. By dispersion of the powders in simulated lung fluid, initial nanoparticle sizes could be recovered for samples containing mannitol. The fraction of redispersed nanoparticles was increased with increasing mannitol content. To evaluate the disintegration under conditions with higher comparability to the in vivo situation, spray-dried powders were exposed to >90% relative humidity. The disintegration behavior was monitored by analyzing roughness values by white light interferometry and supporting SEM imaging. The exposure to high relative humidity was shown to be sufficient for disintegration of the microparticles containing mannitol, releasing morphologically unchanged nanoparticles. With increasing mannitol content, the disintegration occurred faster and to a

Study of the spectra of silica colloidal crystals with assembled silver obtained from a photolysis method

Science.gov (United States)

Li, Wenjiang; He, Jinglong; He, Sailing

2005-02-01

The colorful artificial 3D silica colloidal crystals (opal) were prepared through self-assembly of silica spheres in the visible frequency range. We directly synthesized nano silver particles in the void of the silica artificial opal film using the photolysis of silver nitrate under UV light, nano silver particles were self-deposited around the surface of silica sphere. The shifts of the stop band of the artificial crystals after exposing different time under UV light were studied. Synthetic silica opal with three-dimensional (3D) structure is potentially useful for the development of diffractive optical devices, micro mechanical systems, and sensory elements because photonic band gaps obtained from self-assembled closely packed periodic structures.

Silica artificial opal incorporated with silver nanoparticles

Energy Technology Data Exchange (ETDEWEB)

Li Wenjiang, E-mail: wjli@zju.edu.cn [Center for Optical and Electromagnetic Research, State Key Laboratory for Modern Optical Instrumentation, Zhejiang University, Joint Research Center of Photonics of the Royal Institute of Technology and Zhejiang University, Zijingang Campus, Room 210, East Building 5, Hangzhou 310058 (China); Sun Tan [Center for Optical and Electromagnetic Research, State Key Laboratory for Modern Optical Instrumentation, Zhejiang University, Joint Research Center of Photonics of the Royal Institute of Technology and Zhejiang University, Zijingang Campus, Room 210, East Building 5, Hangzhou 310058 (China)

2009-07-15

The silica artificial opal with a three-dimensional (3D) periodic structure was prepared using highly monodispersed silica microspheres by a force packing method in ITO glass cell. The silica artificial opal incorporated with silver nanoparticles was fabricated by the electroplating technique. The optical microscope images of the synthetic sample and the corresponding optical properties were measured after each treatment of electroplating-washing-drying circle. The transmission and reflection spectra presented a red shift, showing that the effective refractive index of the complex silver/silica opal increased after each electroplating. Combining the SEM images, it was seen that the silver nanoparticles could be directly deposited on the surface of silica spheres in the opaline structure. The silver/silica complex opal film could provide a simple way to tune the opal properties by controlling silver nanoparticles in the silica opal. The silver/silica opal crystal structures could be used for nano-photonic circuits, white-light LEDs or as photocatalysts.

Silica artificial opal incorporated with silver nanoparticles

International Nuclear Information System (INIS)

Li Wenjiang; Sun Tan

2009-01-01

The silica artificial opal with a three-dimensional (3D) periodic structure was prepared using highly monodispersed silica microspheres by a force packing method in ITO glass cell. The silica artificial opal incorporated with silver nanoparticles was fabricated by the electroplating technique. The optical microscope images of the synthetic sample and the corresponding optical properties were measured after each treatment of electroplating-washing-drying circle. The transmission and reflection spectra presented a red shift, showing that the effective refractive index of the complex silver/silica opal increased after each electroplating. Combining the SEM images, it was seen that the silver nanoparticles could be directly deposited on the surface of silica spheres in the opaline structure. The silver/silica complex opal film could provide a simple way to tune the opal properties by controlling silver nanoparticles in the silica opal. The silver/silica opal crystal structures could be used for nano-photonic circuits, white-light LEDs or as photocatalysts.

Morphology of Poly lactide/Polycaprolactone (PLA/PCL) Nano composite by Scanning Electron Microscopy (SEM)

International Nuclear Information System (INIS)

Siti Zulaiha Hairaldin; Wan Md Zin Wan Yunus; Norazowa Ibrahim

2011-01-01

In this study, Octadecylamine Modified Montmorillonites (ODAMMT) were used to prepare Poly lactide/ Polycaprolactone (PLA/ PCL) nano composites. PLA and PCL mix in 90:10 ratios, using an internal mixer by melt blending technique. The other sample was blend with Natrium Montmorillonite (NaMMT) and Octadecylamine Modified Montmorillonite (ODA-MMT) to produce PLA/ PCL-NaMMT and PLA/ PCL ODAMMT. To characterize the polymer nano composites, X-ray diffraction (XRD), FTIR and SEM analysis were conducted. Comparison of morphology were made up between PLA/ PCL, PLA/ PCL with presence of 7 % of Na-MMT and 7 % ODA-MMT respectively based on SEM micrograph by calculate the number-average diameter. (author)

Gas transport behavior of mixed-matrix membranes composed of silica nanoparticles in a polymer of intrinsic microporosity (PIM-1)

KAUST Repository

Ahn, Juhyeon; Chung, Wookjin; Pinnau, Ingo; Song, Jingshe; Du, Naiying; Robertson, Gilles P.; Guiver, Michael D.

2010-01-01

Recently, high-free volume, glassy ladder-type polymers, referred to as polymers of intrinsic microporosity (PIM), have been developed and their reported gas transport performance exceeded the Robeson upper bound trade-off for O2/N2 and CO2/CH4. The present work reports the gas transport behavior of PIM-1/silica nanocomposite membranes. The changes in free volume, as well as the presence and volume of the void cavities, were investigated by analyzing the density, thermal stability, and nano-structural morphology. The enhancement in gas permeability (e.g., He, H2, O2, N2, and CO2) with increasing filler content shows that the trend is related to the true silica volume and void volume fraction. Crown Copyright © 2009.

Stacked dipole line source excitation of active nano-particles

DEFF Research Database (Denmark)

Arslanagic, Samel

This work investigates electromagnetic properties of cylindrical active coated nano-particles excited by a stac- ked electric dipole line source. The nano-particles consist of a silica nano-core, layered by silver, gold, or copper nano-shell. Attention is devoted to the influence of the source...... location and dipole orientation, the gain constant, and the nano-particle material composition on the electromagnetic field distributions and radiated powers. The results are contrasted to those for the magnetic line source illumination of the nano-particles....

FeCl 3 .nano SiO 2 : An Efficient Heterogeneous Nano Catalyst for ...

African Journals Online (AJOL)

dibenzo[a,j]xanthenes and 1,8-dioxo-octahydroxanthenes is described through one-pot condensation of 2-naphthol and dimedone with aryl aldehydes in the presence of nano silica-supported ferric chloride under solvent-free conditions.

Structural and optical studies of nano-structure silica gel doped with different rare earth elements, prepared by two different sol -gel techniques

International Nuclear Information System (INIS)

Battisha, I.K.; El Beyally, A.; Seliman, S.I.; El Nahrawi, A.S.

2005-01-01

Structural and optical characteristics of pure silica gel (silica-xerogel, SiO 2 ) and doped with different concentrations ranging from 1 up to 6% of some rare earth (REEs) ions such as, praseodymium Pr +3 ,and Europium Eu +3 , Erbium Er +3 and Holmium Ho +3 , ions, in the form of thin film and monolith materials were prepared by sol - gel technique, Using tetra-ethoxysilane as precursor materials, which are of particular interest for sol-gel integrated optics applications. Some structural and optical features of sol-gel derived monolith and thin films are analyzed and compared, namely the structure of nano-particle monolith and thin film silica-gel samples, based on X-ray diffraction (XRD). The types of structural information obtainable are compared in detail. It is show that the XRD spectra of a-cristobalite are obtained for the two type materials and even by doping with the four REEs ions. Optical measurements of monolith and thin films were also studied and compared, the normal transmission and specular reflection were measured. The refractive index were calculated and discussed

Synthesis Of Silver Nanoparticles Supported On Silica Using As Antifungal Agent By Gamma Irradiation

International Nuclear Information System (INIS)

Nguyen Thi Kim Lan; Nguyen Tue Anh; Dang Van Phu; Vo Kim Lang; Nguyen Thuy Khanh; Nguyen Quoc Hien

2011-01-01

Silver nanoparticles supported on silica (Ag nano/SiO 2 ) were prepared by gamma Co-60 irradiation method. The formation of Ag nano doped on silica particles was confirmed by the UV-Vis spectroscopy. The size of silver nanoparticles was characterized by transmission electron microscopy (TEM), X-ray diffraction (XRD) which showed the particle size of Ag nano to be in range of 15-30 nm for Ag + concentration 10 mM. In addition, antifungal activity of Ag nano/SiO 2 was tested against Aspergillus niger var Tieghn by plate count method. The results indicated that the antifungal efficiency of Ag nano/SiO 2 was about 64, 71, 81, 82 and 96% at the concentrations of Ag nanoparticles of 30, 50, 70, 100 and 150 ppm respectively. (author)

Immunohistochemical characterization of nanocrystalline hydroxyapatite silica gel (NanoBone(r)) osteogenesis: a study on biopsies from human jaws.

Science.gov (United States)

Götz, Werner; Gerber, Thomas; Michel, Barbara; Lossdörfer, Stefan; Henkel, Kai-Olaf; Heinemann, Friedhelm

2008-10-01

Bone substitute biomaterials may be osteogenic, osteoconductive or osteoinductive. To test for these probable characteristics in a new nanoporous grafting material consisting of nanocrystalline hydroxyapatite embedded in a porous silica gel matrix (NanoBone(s)), applied in humans, we studied biopsies from 12 patients before dental implantation following various orofacial augmentation techniques with healing times of between 3.5 and 12 months. Sections from decalcified specimens were investigated using histology, histochemistry [periodic acid Schiff, alcian blue staining and tartrate-resistant acid phosphatase (TRAP)] and immunohistochemistry, with markers for osteogenesis, bone remodelling, resorption and vessel walls (alkaline phosphatase, bone morphogenetic protein-2, collagen type I, ED1, osteocalcin, osteopontin, runx2 and Von-Willebrand factor). Histologically, four specific stages of graft transformation into lamellar bone could be characterized. During early stages of healing, bone matrix proteins were absorbed by NanoBone(s) granules, forming a proteinaceous matrix, which was invaded by small vessels and cells. We assume that the deposition of these molecules promotes early osteogenesis in and around NanoBone(s) and supports the concomitant degradation probably by osteoclast-like cells. TRAP-positive osteoclast-like cells were localized directly on the granular surfaces. Runx2-immunoreactive pre-osteoblasts, which are probably involved in direct osteogenesis forming woven bone that is later transformed into lamellar bone, were attracted. Graft resorption and bone apposition around the graft granules appear concomitantly. We postulate that NanoBone(s) has osteoconductive and biomimetic properties and is integrated into the host's physiological bone turnover at a very early stage.

Morphology studies on gas hydrates interacting with silica gel

Energy Technology Data Exchange (ETDEWEB)

Beltran, J.; Servio, P. [McGill Univ., Montreal, PQ (Canada). Dept. of Chemical Engineering

2008-07-01

Clathrate hydrates or gas hydrates are non-stoichiometric, crystalline compounds that form when small molecules come in contact with water at certain temperatures and pressures. Natural gas hydrates are found in the ocean bottom and in permafrost regions. It is thought that the amount of energy stored in natural hydrates is at least twice that of all other fossil fuels combined. In addition, trapping carbon dioxide as a hydrate in the bottom of the ocean has been suggested as an alternative means of reducing atmospheric carbon dioxide levels. Naturally occurring clathrates are found in close interaction with fine grained particles of very small mean pore diameters. Even though an increasing amount of hydrate equilibrium data for small diameter porous media has become available, the morphological behavior of hydrates subject to such conditions is yet to be explored. This paper presented a study that visually examined hydrate formation and decomposition of gas hydrates while interacting with fine grains of silica gel. The study showed still frames from high-resolution video recordings for hydrate formation and decomposition. The paper discussed the experiment including the apparatus as well as the results of hydrate formation and hydrate dissociation. This study enabled for the first time to observe clathrate morphology while hydrates interacted closely with fine grain particles with small mean pore diameters. 9 refs., 8 figs.

Combined effect of nano-SiO2 and nano-Fe2O3 on compressive strength, flexural strength, porosity and electrical resistivity in cement mortars

International Nuclear Information System (INIS)

Sanjuán, M.A.; Argiz, C.; Gálvez, J.C.; Reyes, E.

2018-01-01

The compressive strength, flexural strength, porosity and electrical resistivity properties of cement mortars with nano-Fe2O3 and nano-SiO2 are studied. Amorphous silica is the main component of pozzolanic materials due to its reaction with calcium hydroxide formed from calcium silicate (C3S and C2S) hydration. The pozzolanic reaction rate is not only proportional to the amount of amorphous silica but also to the surface area available for reaction. Subsequently, fine nano-Fe2O3 and nano-SiO2 particles in mortars are expected to improve mortar performance. The experimental results showed that the compressive strength of mortars with nano-Fe2O3 and nano-SiO2 particles were lower than those obtained with the reference mortar at seven and 28 days. It was shown that the nano-particles were not able to enhance mechanical strength on every occasion. The continuous microstructural progress monitored by mercury intrusion porosimetry (MIP) measurements, pore-size distribution (PSD), total porosity and critical pore diameter also confirmed such results. [es

Combined effect of nano-SiO2 and nano-Fe2O3 on compressive strength, flexural strength, porosity and electrical resistivity in cement mortars

Directory of Open Access Journals (Sweden)

M. A. Sanjuán

2018-03-01

Full Text Available The compressive strength, flexural strength, porosity and electrical resistivity properties of cement mortars with nano-Fe2O3 and nano-SiO2 are studied. Amorphous silica is the main component of pozzolanic materials due to its reaction with calcium hydroxide formed from calcium silicate (C3S and C2S hydration. The pozzolanic reaction rate is not only proportional to the amount of amorphous silica but also to the surface area available for reaction. Subsequently, fine nano-Fe2O3 and nano-SiO2 particles in mortars are expected to improve mortar performance. The experimental results showed that the compressive strength of mortars with nano-Fe2O3 and nano-SiO2 particles were lower than those obtained with the reference mortar at seven and 28 days. It was shown that the nano-particles were not able to enhance mechanical strength on every occasion. The continuous microstructural progress monitored by mercury intrusion porosimetry (MIP measurements, pore-size distribution (PSD, total porosity and critical pore diameter also confirmed such results.

Morphological characterization of tungsten trioxide nano powders synthesized by Sol-Gel modified Pechini's method

International Nuclear Information System (INIS)

Ghasemi, Leila; Jafari, Hassan

2017-01-01

Sol-gel modified Pechini's method was used to prepare WO 3 nano powders using dicarboxylic acid and polyethylene glycol as the chelating agent and polymeric source, respectively. WO 3 powders were first prepared by calcination of resin precursor at 550 deg C under various initial concentrations of metal ion (12.5-50 mmol), acid (125-500 mmol), a complexing agent (32-262 mmol), and polyethylene glycol (1-16.5 mmol) in the air atmosphere. The products were characterized using X-ray powder diffraction, field emission scanning electron microscopy, and energy dispersive spectroscopy. The results revealed that the WO 3 nano powders prepared with different amounts of chelating agent and polyethylene glycol, crystallized in monoclinic phase. The nano powders were impurity-free due to the presence of the complexing agent and polyethylene glycol as carbon sources. Morphological evolution indicated that the nano powders evolved from rod-like to regular and spherical shapes, depending on complexing agent and polyethylene glycol amounts. Nano powders with an average particle size of approximately 58 nm and a narrow size distribution were obtained. (author)

Morphological characterization of tungsten trioxide nano powders synthesized by Sol-Gel modified Pechini's method

Energy Technology Data Exchange (ETDEWEB)

Ghasemi, Leila; Jafari, Hassan, E-mail: jafari_h@yahoo.com [Department of Materials Engineering, Faculty of Mechanical Engineering, Shahid Rajaee Teacher Training University, Tehran (Iran, Islamic Republic of)

2017-11-15

Sol-gel modified Pechini's method was used to prepare WO{sub 3} nano powders using dicarboxylic acid and polyethylene glycol as the chelating agent and polymeric source, respectively. WO{sub 3} powders were first prepared by calcination of resin precursor at 550 deg C under various initial concentrations of metal ion (12.5-50 mmol), acid (125-500 mmol), a complexing agent (32-262 mmol), and polyethylene glycol (1-16.5 mmol) in the air atmosphere. The products were characterized using X-ray powder diffraction, field emission scanning electron microscopy, and energy dispersive spectroscopy. The results revealed that the WO{sub 3} nano powders prepared with different amounts of chelating agent and polyethylene glycol, crystallized in monoclinic phase. The nano powders were impurity-free due to the presence of the complexing agent and polyethylene glycol as carbon sources. Morphological evolution indicated that the nano powders evolved from rod-like to regular and spherical shapes, depending on complexing agent and polyethylene glycol amounts. Nano powders with an average particle size of approximately 58 nm and a narrow size distribution were obtained. (author)

Impact of the Excitation Source and Plasmonic Material on Cylindrical Active Coated Nano-Particles

DEFF Research Database (Denmark)

Arslanagic, Samel; Liu, Yan; Malureanu, Radu

2011-01-01

Electromagnetic properties of cylindrical active coated nano-particles comprised of a silica nano-cylinder core layered with a plasmonic concentric nano-shell are investigated for potential nano-sensor applications. Particular attention is devoted to the near-field properties of these particles...

Effect of electric field distribution on the morphologies of laser-induced damage in hafnia-silica multilayer polarizers

International Nuclear Information System (INIS)

Genin, F.Y.; Stolz, C.J.; Reitter, T.; Kozlowski, M.R.; Bevis, R.P.; vonGunten, M.K.

1997-01-01

Hafnia-silica multilayer polarizers were deposited by e-beam evaporation onto BK7 glass substrates. The polarizers were designed to operate at 1064 nm at Brewster's angle (56 degree). They were tested with a 3-ns laser pulse at 45, 56, and 65 degree incidence angle in order to vary the electric field distribution in the multilayer, study their effects on damage morphology, and investigate possible advantages of off-use angle laser conditioning. Morphology of the laser-induced damage was characterized by optical and scanning electron microscopy. Four distinct damage morphologies (pit, flat bottom pit, scald, outer layer delamination) were observed; they depend strongly on incident angle of the laser beam. Massive delamination observed at 45 and 56 degree incidence, did not occur at 65 degree; instead, large and deep pits were found at 65 degree. Electric field distribution, temperature rise, and change in stress in the multilayer were calculated to attempt to better understand the relation between damage morphology, electric field peak locations, and maximum thermal stress gradients. The calculations showed a twofold increase in stress change in the hafnia top layers depending on incident angle. Stress gradient in the first hafnia-silica interface was found to be highest for 45, 56, and 65 degree, respectively. Finally, the maximum stress was deeper in the multilayer at 65 degree. Although the limitations of such simple thermal mechanical model are obvious, the results can explain that outer layer delamination is more likely at 45 and 56 degree than 65 degree and that damage sites are expected to be deeper at 65 degree

Controlling Foam Morphology of Poly(methyl methacrylate via Surface Chemistry and Concentration of Silica Nanoparticles and Supercritical Carbon Dioxide Process Parameters

Directory of Open Access Journals (Sweden)

Deniz Rende

2013-01-01

Full Text Available Polymer nanocomposite foams have received considerable attention because of their potential use in advanced applications such as bone scaffolds, food packaging, and transportation materials due to their low density and enhanced mechanical, thermal, and electrical properties compared to traditional polymer foams. In this study, silica nanofillers were used as nucleating agents and supercritical carbon dioxide as the foaming agent. The use of nanofillers provides an interface upon which CO2 nucleates and leads to remarkably low average cell sizes while improving cell density (number of cells per unit volume. In this study, the effect of concentration, the extent of surface modification of silica nanofillers with CO2-philic chemical groups, and supercritical carbon dioxide process conditions on the foam morphology of poly(methyl methacrylate, PMMA, were systematically investigated to shed light on the relative importance of material and process parameters. The silica nanoparticles were chemically modified with tridecafluoro-1,1,2,2-tetrahydrooctyl triethoxysilane leading to three different surface chemistries. The silica concentration was varied from 0.85 to 3.2% (by weight. The supercritical CO2 foaming was performed at four different temperatures (40, 65, 75, and 85°C and between 8.97 and 17.93 MPa. By altering the surface chemistry of the silica nanofiller and manipulating the process conditions, the average cell diameter was decreased from 9.62±5.22 to 1.06±0.32 μm, whereas, the cell density was increased from 7.5±0.5×108 to 4.8±0.3×1011 cells/cm3. Our findings indicate that surface modification of silica nanoparticles with CO2-philic surfactants has the strongest effect on foam morphology.

Near-field enhanced femtosecond laser nano-drilling of glass substrate

International Nuclear Information System (INIS)

Zhou, Y.; Hong, M.H.; Fuh, J.Y.H.; Lu, L.; Lukyanchuk, B.S.; Wang, Z.B.

2008-01-01

Particle mask assisted near-field enhanced femtosecond laser nano-drilling of transparent glass substrate was demonstrated in this paper. A particle mask was fabricated by self-assembly of spherical 1 μm silica particles on the substrate surface. Then the samples were exposed to femtosecond laser (800 nm, 100 fs) and characterized by field emission scanning electron microscope (FESEM) and atomic force microscope (AFM). The nano-hole array was found on the glass surface. The hole sizes were measured from 200 to 300 nm with an average depth of 150 nm and increased with laser fluence. Non-linear triple-photon absorption and near-field enhancement were the main mechanisms of the nano-feature formation. Calculations based on Mie theory shows an agreement with experiment results. More debris, however, was found at high laser fluence. This can be attributed to the explosion of silica particles because the focusing point is inside the 1 μm particle. The simulation predicts that the focusing point will move outside the particle if the particle size increases. The experiment performed under 6.84 μm silica particles verified that no debris was formed. And for all the samples, no cracks were found on the substrate surface because of ultra-short pulse width of femtosecond laser. This method has potential applications in nano-patterning of transparent glass substrate for nano-structure device fabrication

A New Insight into Morphology of Solvent Resistant Nano filtration Membranes: Image Processing Assisted Review

International Nuclear Information System (INIS)

Pouresmaeel-Selakjani, P.; Jahanshahi, M.; Peyravi, M.; Fauzi Ismail, A.; Nabipoor, M. R.

2016-01-01

The aim of this review is to investigate the morphological properties of polyimide based Solvent Resistant Nano filtration membranes by mean of image processing. Effect of phase inversion parameters like polymer concentration, volatile co-solvent, pre-evaporation time, additives in coagulation bath, polymers weight ratio in composite membranes, addition of nano particles and cross-linking agents have been reviewed. The voids of membrane were targeted to survey in the aspect of void area concentration in the scanning electron microscopy micrograph, mean of voids area, voids orientation and circle equivalent diameters of voids. This method by mean of the developed software could make the morphological studies of membranes easy. The population of different measured parameters of the voids could also measure. In conclusion for polyimide based membranes there are specific trends for change in voids properties by changing of phase inversion parameters. It was predictable, but investigated qualitatively up to now and this review can confirm the qualitative observations and also open new discussions about, for example void orientations that are not investigated in any study up to now

Nano-Ag complexes prepared by γ-radiolysis and their structures and physical properties

International Nuclear Information System (INIS)

Kim, Hwa-Jung; Choi, Seong-Ho; Park, Hae-Jun

2012-01-01

In this study, nano-silver (nano-Ag) complexes showing different properties have been synthesized as follows. Polypyrrolidone (PVP)-stabilized silver colloids (NAg), nano-Ag bound to silica (SiO 2 ) (NSS), and nano-Ag bound to a complex of SiO 2 and polyaniline (PANI) (NSSPAI) were prepared via γ-irradiation at room temperature. NAg and NSS used PVP as a colloidal stabilizer, while NSSPAI did not use PVP as a colloidal stabilizer. Interesting bonding properties occurred in the nano-Ag complex and anticipated structural changes were clearly shown through a surface analysis of x-ray photoelectron spectroscopy (XPS). The morphologies by field emission-scanning electron microscopy (FE-SEM) analysis showed that nano-Ag complexes have various particle sizes ranging from 10 to 30 nm. NSS (average, 10 nm) and NSSPAI (average, 30 nm) showed a uniformly spherical shape and size, while NAg did not. From the reflection peaks in the x-ray diffraction (XRD) patterns, surface crystallinity of the nano-Ag complexes was indicated to be in the same degree as that of NSSPAI>NSS>NAg. Also, in the contact angle (CA) determination, surface hydrophobicity of NSSPAI was stronger than those of NSS and NAg, relatively. The different nano-Ag complexes prepared by γ-irradiation can be applicable in various industry fields due to the increase in specific property. - Highlights: ► Nano-Ag complexes showing different properties have been synthesized via γ-irradiation. ► Nano-Ag colloid (NAg), nano-Ag bound to SiO 2 (NSS), nano-Ag bound to SiO 2 and PANI complex (NSSPAI). ► Nano-Ag complexes were the same based on Ag metal. ► Results clearly showed fascinating/different physical properties. ► Different nano-Ag complexes can be applicable in various industry fields.

Effect of Addition of Colloidal Silica to Films of Polyimide, Polyvinylpyridine, Polystyrene, and Polymethylmethacrylate Nano-Composites

OpenAIRE

Abdalla, Soliman; Al-Marzouki, Fahad; Obaid, Abdullah; Gamal, Salah

2016-01-01

Nano-composite films have been the subject of extensive work for developing the energy-storage efficiency of electrostatic capacitors. Factors such as polymer purity, nanoparticle size, and film morphology drastically affect the electrostatic efficiency of the dielectric material that forms the insulating film between the conductive electrodes of a capacitor. This in turn affects the energy storage performance of the capacitor. In the present work, we have studied the dielectric properties of...

Nano-Welding of Multi-Walled Carbon Nanotubes on Silicon and Silica Surface by Laser Irradiation

Directory of Open Access Journals (Sweden)

Yanping Yuan

2016-02-01

Full Text Available In this study, a continuous fiber laser (1064 nm wavelength, 30 W/cm2 is used to irradiate multi-walled carbon nanotubes (MWCNTs on different substrate surfaces. Effects of substrates on nano-welding of MWCNTs are investigated by scanning electron microscope (SEM. For MWCNTs on silica, after 3 s irradiation, nanoscale welding with good quality can be achieved due to breaking C–C bonds and formation of new graphene layers. While welding junctions can be formed until 10 s for the MWCNTs on silicon, the difference of irradiation time to achieve welding is attributed to the difference of thermal conductivity for silica and silicon. As the irradiation time is prolonged up to 12.5 s, most of the MWCNTs are welded to a silicon substrate, which leads to their frameworks of tube walls on the silicon surface. This is because the accumulation of absorbed energy makes the temperature rise. Then chemical reactions among silicon, carbon and nitrogen occur. New chemical bonds of Si–N and Si–C achieve the welding between the MWCNTs and silicon. Vibration modes of Si3N4 appear at peaks of 363 cm−1 and 663 cm−1. There are vibration modes of SiC at peaks of 618 cm−1, 779 cm−1 and 973 cm−1. The experimental observation proves chemical reactions and the formation of Si3N4 and SiC by laser irradiation.

Nano-Welding of Multi-Walled Carbon Nanotubes on Silicon and Silica Surface by Laser Irradiation

Science.gov (United States)

Yuan, Yanping; Chen, Jimin

2016-01-01

In this study, a continuous fiber laser (1064 nm wavelength, 30 W/cm2) is used to irradiate multi-walled carbon nanotubes (MWCNTs) on different substrate surfaces. Effects of substrates on nano-welding of MWCNTs are investigated by scanning electron microscope (SEM). For MWCNTs on silica, after 3 s irradiation, nanoscale welding with good quality can be achieved due to breaking C–C bonds and formation of new graphene layers. While welding junctions can be formed until 10 s for the MWCNTs on silicon, the difference of irradiation time to achieve welding is attributed to the difference of thermal conductivity for silica and silicon. As the irradiation time is prolonged up to 12.5 s, most of the MWCNTs are welded to a silicon substrate, which leads to their frameworks of tube walls on the silicon surface. This is because the accumulation of absorbed energy makes the temperature rise. Then chemical reactions among silicon, carbon and nitrogen occur. New chemical bonds of Si–N and Si–C achieve the welding between the MWCNTs and silicon. Vibration modes of Si3N4 appear at peaks of 363 cm−1 and 663 cm−1. There are vibration modes of SiC at peaks of 618 cm−1, 779 cm−1 and 973 cm−1. The experimental observation proves chemical reactions and the formation of Si3N4 and SiC by laser irradiation. PMID:28344293

Morphologies of laser-induced damage in hafnia-silica multilayer mirror and polarizer coatings

International Nuclear Information System (INIS)

Genin, F.Y.; Stolz, C.J.

1996-08-01

Hafnium-silica multilayer mirrors and polarizers were deposited by e-beam evaporation onto BK7 glass substrates. The mirrors and polarizers were coated for operation at 1053 nm at 45 degree and at Brewster's angle (56 degree), respectively. They were tested with a single 3-ns laser pulse. Morphology of the laser-induced damage was characterized by optical and scanning electron microscopy. Four distinct damage morphologies were found: pits, flatbottom pits, scalds, and delaminates. The pits and flat bottom pits ( 2 ). The pits seemed to result from ejection of nodular defects by causing local enhancement of the electric field. Scalds and delaminates could be observed at higher fluences (above 13 J/cm 2 ) and seemed to result from the formation of plasmas on the surface. These damage types often originated at pits and were less than 300 μm diameter; their size increased almost linearly with fluence. Finally, effects of the damage on the beam (reflectivity degradation and phase modulations) were measured

Luminescent Eosin Y–SiO2 hybrid nano and microrods prepared by sol–gel template method

International Nuclear Information System (INIS)

Secu, M.; Secu, C.E.; Sima, M.; Negrea, R.F.; Bartha, C.; Dinescu, M.; Damian, V.

2013-01-01

Sol–gel chemistry within the pores of a polycarbonate template membrane was used for the preparation of Eosin Y–SiO 2 hybrid nano- and microrods, using tetraethylorthosilicate [TEOS, Si(OC 2 H 5 ) 4 ] as the precursor in the presence of trifluoroacetic acid (TFA) catalyst. The ethanolic solution of Eosin-Y was added to the silica sol to trap dye molecules inside the SiO 2 gel network during the gelation. Structural and morphological characterization using scanning electron microscopy (SEM) and luminescence microscopy have shown the formation of rods with 200 nm and 1.2 μm diameter and about 30 μm length, exhibiting luminescence properties. Spectroscopic characterization has shown that the luminescence is due to Eosin-Y molecule in the xerogel porous network, surrounded by a solvation shell given mainly by the water. -- Highlights: • Sol–gel template method was used to prepare Eosin Y–SiO 2 hybrid rods-type structures. • Morphological characterization has shown nano- and microrods with luminescent properties. • Luminescence is due to Eosin-Y molecule surrounded by a solvation shell given by water

Synthesis and characterization of nano hydroxyapatite using reverse micro emulsions as nano reactors

International Nuclear Information System (INIS)

Amin, S.; Siddique, T.

2015-01-01

In the present work reverse micro emulsion has been employed as nano reactors to synthesize nano crystalline Hydroxyapatite (HA). Two precursors; calcium and phosphate with different counter ions of each were used for the synthesis of HA at two different temperatures. To maintain the emulsified nano reactor, cyclohexane, TX-100 and 1-butanol including phosphate precursor was the continuous phase while aqueous Ca precursor solution was taken as the dispersed phase. Nano crystalline particles thus produced were evaluated on the basis of synthesis route, counter ions and temperature. It has been shown that emulsified nano reactors control the morphology, particle size and minimize phase transformation of HA. Characterizations of nano powder of HA are carried out using x-ray diffraction (XRD), Fourier transform infra-red spectroscopy (FTIR), and scanning electron microscopy (SEM). HA crystallite size was found to be in the range of 20-25 nm whereas the morphology of nano particles changed from spheres to rods. (author)

Synthesis and Characterization of Si Oxide Coated Nano Ceria by Hydrolysis, and Hydrothermal Treatment at Low Temperature

Directory of Open Access Journals (Sweden)

Kong M.

2017-06-01

Full Text Available The purpose of this work was to the application of Si oxide coatings. This study deals with the preparation of ceria (CeO2 nanoparticles coating with SiO2 by water glass and hydrolysis reaction. First, the low temperature hydro-reactions were carried out at 30~100°C. Second, Silicon oxide-coated Nano compounds were obtained by the catalyzing synthesis. CeO2 Nano-powders have been successfully synthesized by means of the hydrothermal method, in a low temperature range of 100~200°C. In order to investigate the structure and morphology of the Nano-powders, scanning electron microscopy (SEM and X-ray diffraction (XRD were employed. The XRD results revealed the amorphous nature of silica nanoparticles. To analyze the quantity and properties of the compounds coated with Si oxide, transmission electron microscopy (TEM in conjunction with electron dispersive spectroscopy was used. Finally, it is suggested that the simple growth process is more favorable mechanism than the solution/aggregation process.

Silicon Conversion From Bamboo Leaf Silica By Magnesiothermic Reduction for Development of Li-ion Baterry Anode

Directory of Open Access Journals (Sweden)

Silviana Silviana

2018-01-01

Full Text Available Silicon (Si is a promising alternative material for the anode Lithium ion Battery (LIB. Si has a large theoretical capacity about 3579 mA hg-1, ten times greater than the commercial graphite anode (372 mA hg-1. Bamboo is a source of organic silica (bio-silica. Most part biogenetic content of SiO2 is obtained in bamboo leaves. This paper aims to investigate the synthesis nano Si from bamboo leaves through magnesiothermic reduction after silica extraction using sol–gel method and to observe nano Si of bamboo leaf as mixed material for lithium ion baterry. Silica and silicon content was determined using XRF. Silica product has 96,3 wt. % yield of extraction from bamboo leaf, while silicon yield was obtained 61.2 wt. %. The XRD pattern revealed that silica and silicon product were amourphous. The extracted silica and silicon from bambo leaf has spherical shape and agglomerated form. As anoda material for LIB, silicon product achieved 0,002 mAh capacity for 22 cycle.

The Effect of Nano Calcium and Potassium Humic Acid Fertilizer on Morphological and Biochemical Traits of Nasturtium (Tropaeolum majus (

Directory of Open Access Journals (Sweden)

l salehi

2017-12-01

Full Text Available Today with regard to environmental pollution caused by chemical fertilizers and finding an alternative to these fertilizers, Consideration has been given to the use of other products in this field. Accordingly, In order To study the effect of Nano calcium and Humi potas on morphological and biochemical traits of nasturtium, this factorial experiment was conducted in a randomized complete block design with 3 replications. The experiment was carried out at Shahid Chamran University of Ahvaz in 2013-2014. In this study, morphological traits, length and diameter of stem, number and leaf area, number of lateral branches, number of flowers and seeds, fresh and dry weight of leaves, stems and roots and biochemical traits, total chlorophyll, calcium and potassium absorption Evaluated. The results showed that the interaction of two treatments in all studied traits, except for stem length and diameter, number of flowers and number of branches, was significant. According to the results of the best condition in the studied traits, we observed interaction effects of concentration of 2 in 1000 Nano calcium with 500 and 1000 ppm Humi Potasses. Both treatments had a non-significant difference and Showed a significant difference compared to control treatment. In general, the application of concentration of 2 per thousand Nano calcium with different levels of Humi potash fertilizer improved morphological and biochemical traits in Nasturtium flowers.

Spherical active coated nano-particles – impact of the electric Hertzian dipole orientation

DEFF Research Database (Denmark)

Arslanagic, Samel; Mostafavi, M.; Malureanu, Radu

2011-01-01

Spherical active coated nano-particles comprised of a silica nano-cylinder core covered with a plasmonic nano-shell are investigated with regard to their near- and far-field properties. The source of excitation is taken to be that of a tangential or a radial electric Hertizan dipole while three...

Partial hydrogenation of alkynes on highly selective nano-structured mesoporous silica MCM-41 composite catalyst

International Nuclear Information System (INIS)

Kojoori, R.K.

2016-01-01

In this research, we have developed a silica MCM-41/Metformin/Pd (II) nano composite catalyst for the selective hydrogenation of alkynes to the corresponding (Z)-alkenes under a mild condition of atmospheric pressure and room temperature. Firstly, functionalized Si-MCM-41 metformin catalyst with the optimum performance was prepared. Then, the synthesized catalyst was elucidated by X-ray powder diffraction, BET surface area, FT-IR spectrophotometer, Scanning electron microscopy (SEM) and Transmission electron microscopy (TEM) and applied in partial hydrogenation of different alkynes, with high selectivity and high yield. The products were characterized by 1H-NMR, 13C-NMR, FT-IR, and Mass Spectrometry (MS) that strongly approved the (Z)-double bond configuration of produced alkenes. This prepared catalyst is competitive with the best palladium catalysts known for the selective liquid phase hydrogenation of alkynes and can be easily recovered and regenerated with keeping high activity and selectivity over at least three cycles with a simple regeneration procedure. (author)

Mannose-functionalized porous silica-coated magnetic nanoparticles for two-photon imaging or PDT of cancer cells

International Nuclear Information System (INIS)

Perrier, Marine; Gary-Bobo, Magali; Lartigue, Lenaïc; Brevet, David; Morère, Alain; Garcia, Marcel; Maillard, Philippe; Raehm, Laurence; Guari, Yannick; Larionova, Joulia; Durand, Jean-Olivier; Mongin, Olivier; Blanchard-Desce, Mireille

2013-01-01

An original fluorophore engineered for two-photon excitation or a porphyrin derivative were entrapped in the silica shell of magnetic porous silica nanoparticles during the synthesis of the silica moiety without damaging the structure of the organic part. The mild conditions involved allowed obtaining microporous or mesoporous silica magnetic nanoparticles, respectively. Mannose was grafted on the surface of the nanoparticles to target MCF-7 breast cancer cells. The studies of magnetic properties of these hybrid nanoparticles show that they present a blocking temperature at 190 K. The nano-objects designed with the two-photon fluorophore were efficient for two-photon imaging of MCF-7 cancer cells, whereas the nano-objects with the photosensitizer efficiently killed cancer cells. The presence of the mannose moiety was demonstrated to improve both imaging and therapy properties.

Mannose-functionalized porous silica-coated magnetic nanoparticles for two-photon imaging or PDT of cancer cells

Energy Technology Data Exchange (ETDEWEB)

Perrier, Marine [UMR 5253 CNRS-UM2-ENSCM-UM1, Institut Charles Gerhardt Montpellier (France); Gary-Bobo, Magali [Faculte de Pharmacie, Universite Montpellier 1, Universite Montpellier 2, Institut des Biomolecules Max Mousseron UMR 5247 CNRS (France); Lartigue, Lenaiec; Brevet, David [UMR 5253 CNRS-UM2-ENSCM-UM1, Institut Charles Gerhardt Montpellier (France); Morere, Alain; Garcia, Marcel [Faculte de Pharmacie, Universite Montpellier 1, Universite Montpellier 2, Institut des Biomolecules Max Mousseron UMR 5247 CNRS (France); Maillard, Philippe [Universite Paris-Sud, UMR 176 CNRS, Institut Curie (France); Raehm, Laurence; Guari, Yannick, E-mail: yannick.guari@um2.fr; Larionova, Joulia; Durand, Jean-Olivier, E-mail: durand@univ-montp2.fr [UMR 5253 CNRS-UM2-ENSCM-UM1, Institut Charles Gerhardt Montpellier (France); Mongin, Olivier [Universite de Rennes 1, Institut des Sciences Chimiques de Rennes, CNRS UMR 6226 (France); Blanchard-Desce, Mireille [Universite Bordeaux, Institut des Sciences Moleculaires, UMR CNRS 5255 (France)

2013-05-15

An original fluorophore engineered for two-photon excitation or a porphyrin derivative were entrapped in the silica shell of magnetic porous silica nanoparticles during the synthesis of the silica moiety without damaging the structure of the organic part. The mild conditions involved allowed obtaining microporous or mesoporous silica magnetic nanoparticles, respectively. Mannose was grafted on the surface of the nanoparticles to target MCF-7 breast cancer cells. The studies of magnetic properties of these hybrid nanoparticles show that they present a blocking temperature at 190 K. The nano-objects designed with the two-photon fluorophore were efficient for two-photon imaging of MCF-7 cancer cells, whereas the nano-objects with the photosensitizer efficiently killed cancer cells. The presence of the mannose moiety was demonstrated to improve both imaging and therapy properties.

Improved Optical and Morphological Properties of Vinyl-Substituted Hybrid Silica Materials Incorporating a Zn-Metalloporphyrin

Directory of Open Access Journals (Sweden)

Zoltán Dudás

2018-04-01

Full Text Available This work is focused on a novel class of hybrid materials exhibiting enhanced optical properties and high surface areas that combine the morphology offered by the vinyl substituted silica host, and the excellent absorption and emission properties of 5,10,15,20-tetrakis(N-methyl-4-pyridylporphyrin-Zn(II tetrachloride as a water soluble guest molecule. In order to optimize the synthesis procedure and the performance of the immobilized porphyrin, silica precursor mixtures of different compositions were used. To achieve the requirements regarding the hydrophobicity and the porous structure of the gels for the successful incorporation of porphyrin, the content of vinyltriacetoxysilane was systematically changed and thoroughly investigated. Substitution of the silica gels with organic groups is a viable way to provide new properties to the support. An exhaustive characterization of the synthesized silica samples was realised by complementary physicochemical methods, such as infrared spectroscopy (FT-IR, absorption spectroscopy (UV-Vis and photoluminescence, nuclear magnetic resonance spectroscopy (29Si-MAS-NMR transmission and scanning electron microscopy (TEM and SEM, nitrogen absorption (BET, contact angle (CA, small angle X ray and neutron scattering (SAXS and SANS. All hybrids showed an increase in emission intensity in the wide region from 575 to 725 nm (Q bands in comparison with bare porphyrin. By simply tuning the vinyltriacetoxysilane content, the hydrophilic/hydrophobic profile of the hybrid materials was changed, while maintaining a high surface area. Good control of hydrophobicity is important to enhance properties such as dispersion, stability behaviour, and resistance to water, in order to achieve highly dispersible systems in water for biomedical applications.

Helium concentration in tungsten nano-tendril surface morphology using Elastic Recoil Detection

International Nuclear Information System (INIS)

Woller, K.B.; Whyte, D.G.; Wright, G.M.; Doerner, R.P.; De Temmerman, G.

2013-01-01

Helium (He) concentrations in tungsten nano-tendrils (W fuzz) have been measured for the first time using Elastic Recoil Detection (ERD). Fuzzy and non-fuzzy W surfaces were analyzed in order to illuminate the role of He in the transition in surface morphologies. Samples grown in the PISCES-A and PILOT-PSI experiments allowed a survey of surface temperature ranging from T s = 470–2595 K and of He fluence on the order of Φ He ∼ 10 24 –10 27 ions/m 2 . He concentrations measured in the bulk of W fuzz layers are roughly uniform with bulk He concentration 1–4 at.% while samples with just He in the near surface peaked at 1–2 at.%. This confirms that the nano-tendrils are filled with high pressure He bubbles since the solubility of He in W is ∼10 −5 at.%. This indicates that the ∼1000 K temperature fuzz-growth threshold is determined by the response of the W, not the near-surface He concentration

Influence of the silica fillers on the ageing of epoxy resins under irradiations

International Nuclear Information System (INIS)

Benard, F.

2004-01-01

Various studies were carried out on the ageing of epoxy resins under irradiations. In all cases, pure polymers were studied. The aim of our work managed by the CEA and the CNRS consists on studying the part of fillers and particularly the part of silica on ageing process under electron beam irradiations. Because of their wide use in industrial applications and especially in nuclear environment, the DGEBA-TETA resins (Diglycidylether of Bisphenol A - Triethylenetetramine) were chosen. Those epoxy resins are difficult to analyse because of their insolubility. Some pure and nano-metric silica filled chemical models which chemical structure very close to the one the DGEBA/TETA resin were synthesized and analysed with classical methods in organic chemistry. A major phenomenon of rupture of the C-O and C-N chemical bonds with creation of phenolic extremities, methylketone extremities, of primary and tertiary amines and notably enamine functions were revealed by the analyses. The quantitative 1 H and 13 C NMR analyses revealed the screen effect due to the silica and the reactions between the chemical species created by the irradiations and the silica surface. Thermic and thermodynamic analyses of the different epoxy resins in function of the irradiation dose and of the kind of silica showed the decrease of the glass transition temperature, of the relaxation temperature and of the crosslink density confirming the major phenomenon of bond ruptures during irradiations. With silica, the decrease of the crosslink density is slowed. This phenomenon can be explained with interactions between the nano-metric silica surface and the epoxy resin offsetting the effect of the chain rupture on the resin mechanical properties. The 13 C solid state NMR analyses confirmed the choice of the chemical models and permitted to detect the chemical species created by the irradiations. The analyse of the polarization transfers with 13 C CP-MAS NMR spectroscopy revealed the stiffening of the nano

Super-Hydrophobic/Icephobic Coatings Based on Silica Nanoparticles Modified by Self-Assembled Monolayers

Directory of Open Access Journals (Sweden)

Junpeng Liu

2016-12-01

Full Text Available A super-hydrophobic surface has been obtained from nanocomposite materials based on silica nanoparticles and self-assembled monolayers of 1H,1H,2H,2H-perfluorooctyltriethoxysilane (POTS using spin coating and chemical vapor deposition methods. Scanning electron microscope images reveal the porous structure of the silica nanoparticles, which can trap small-scale air pockets. An average water contact angle of 163° and bouncing off of incoming water droplets suggest that a super-hydrophobic surface has been obtained based on the silica nanoparticles and POTS coating. The monitored water droplet icing test results show that icing is significantly delayed by silica-based nano-coatings compared with bare substrates and commercial icephobic products. Ice adhesion test results show that the ice adhesion strength is reduced remarkably by silica-based nano-coatings. The bouncing phenomenon of water droplets, the icing delay performance and the lower ice adhesion strength suggest that the super-hydrophobic coatings based on a combination of silica and POTS also show icephobicity. An erosion test rig based on pressurized pneumatic water impinging impact was used to evaluate the durability of the super-hydrophobic/icephobic coatings. The results show that durable coatings have been obtained, although improvement will be needed in future work aiming for applications in aerospace.

Photovoltaic's silica-rich waste sludge as supplementary cementitious material (SCM)

International Nuclear Information System (INIS)

Quercia, G.; Putten, J.J.G. van der; Hüsken, G.; Brouwers, H.J.H.

2013-01-01

Waste sludge, a solid recovered from wastewater of photovoltaic-industries, composes of agglomerates of nano-particles like SiO 2 and CaCO 3 . This sludge deflocculates in aqueous solutions into nano-particles smaller than 1 μm. Thus, this sludge constitutes a potentially hazardous waste when it is improperly disposed. Due to its high content of amorphous SiO 2 , this sludge has a potential use as supplementary cementitious material (SCM) in concrete. In this study the main properties of three different samples of photovoltaic's silica-rich waste sludge (nSS) were physically and chemically characterized. The characterization techniques included: scanning electron microscopy (SEM), X-ray energy dispersive spectroscopy (EDS), X-ray diffraction (XRD), nitrogen physical adsorption isotherm (BET method), density by Helium pycnometry, particle size distribution determined by laser light scattering (LLS) and zeta-potential measurements by dynamic light scattering (DLS). In addition, a dispersability study was performed to design stable slurries to be used as liquid additives for the concrete production on site. The effects on the hydration kinetics of cement pastes by the incorporation of nSS in the designed slurries were determined using an isothermal calorimeter. A compressive strength test of standard mortars with 7% of cement replacement was performed to determine the pozzolanic activity of the waste nano-silica sludge. Finally, the hardened system was fully characterized to determine the phase composition. The results demonstrate that the nSS can be utilized as SCM to replace portion of cement in mortars, thereby decreasing the CO 2 footprint and the environmental impact of concrete. -- Highlights: •Three different samples of PV nano-silica sludge (nSS) were fully characterized. •nSS is composed of agglomerates of nano-particles like SiO 2 and CaCO 3 . •Dispersability studies demonstrated that nSS agglomerates are broken to nano-size. •nSS can be classified

Synthesis and characterization of nano structures of Silica SBA-16 containing Gadolinium-159 as potential nanoparticulated system for cancer therapy

International Nuclear Information System (INIS)

Oliveira, Andre Felipe de

2013-01-01

Cancer is a leading cause of death worldwide, and malignant neoplasms of the lung, stomach, liver, colon and breast in greater numbers. And recently observed in the literature a large number of reviews where new materials, especially nanoparticle, has been studied as drug carriers and radioisotopes applied to cancer treatment. How mesoporous materials based on silica, thanks to its huge surface area and biocompatibility, have been studied intensively providing broad applications in various areas, the use of nanostructured silica SBA-16 might be a carrier specific radioisotope accumulate in the cells malignant. Thus the aim of this study is to develop in vitro studies using SBA-16 can selectively concentrate in malignant cells therapeutic amounts of the radioisotope Gadolinium-159 escorting them to death. This work was performed orderly synthesis of mesoporous silica, SBA-16 and incorporating the complex Gd-DTPA-BMA, as well as chemical and structural characterization. The techniques used to analyze the occurrence of the incorporation of the gadolinium complex in the silica matrix were elemental analysis (CHN), atomic emission spectroscopy (ICP-AES), infrared spectroscopy (FTIR), nitrogen adsorption (BET), small-angle X-ray scattering (SAXS) and thermogravimetric analysis (TG). To analyze the morphology of pure silica used the scanning electron microscopy (SEM) and transmission electron microscopy (TEM). By photon correlation spectroscopy (PCS) it was possible to obtain a measure of mean particle size, the polydispersity index (PDI) of the silica SBA-16, and the zeta potential by laser Doppler anemometry (LDA). The results of incorporation analyzed by ICP-AES indicated that the material SBA-16 had a higher rate of incorporation of gadolinium (93%). The release kinetics in simulated body fluid, showed considerable stability and low release (1%). The mesoporous silica SBA-16 showed cell viability in direct contact with cell culture. Samples with gadolinium

On the morphology and potential application of polydimethylsiloxane-silica-titania composites

Directory of Open Access Journals (Sweden)

2011-02-01

Full Text Available Polydimethylsiloxane-α,ω-diol was used as matrix for the preparation of polysiloxane-SiO2-TiO2 composites through in situ incorporation of silica and titania using a solvent-free sol-gel procedure. For this purpose, oxide precursors tetraethyl-orthosilicate and tetrabutyl-orthotitanate, and a proper condensation catalyst, viz. dibuthyltin dilaurate, were added in pre-established amounts to the polymer. The hydrolysis and condensation reactions take place under mild conditions, with the formation of silicon and titanium oxide networks and polymer crosslinking. The effect of SiO2 and TiO2 mass ratio on the morphology of the composites was investigated by scanning electron microscopy (SEM and X-rays diffraction (XRD, and interpreted in correlation with differential scanning calorimetry (DSC and energy-dispersive X-ray spectroscopy (EDX data. The film samples were tested as active elements in actuation devices.

Study of Physical Properties of Nano-Silica Coated Cotton Textiles

OpenAIRE

Sidra Saleemi; Farooq Ahmed; Samandar Malik

2015-01-01

This research was aimed to investigate the effect of silica sol-gel coating on air permeability, stiffness and tensile properties of dyed cotton fabric. Various concentrations of silica nanoparticles were applied on dyed cotton substrate using two different cross-linkers through sol-gel method. The homogenous sol-gel coating dispersions were prepared by using an ultrasonicator. Coated samples were tested for mechanical and comfort properties such as tensile strength, stiffness, crease recover...

Passion fruit-like nano-architectures: a general synthesis route

Science.gov (United States)

Cassano, D.; David, J.; Luin, S.; Voliani, V.

2017-03-01

Noble metal nanostructures have demonstrated a number of intriguing features for both medicine and catalysis. However, accumulation issues have prevented their clinical translation, while their use in catalysis has shown serious efficiency and stability hurdles. Here we introduce a simple and robust synthetic protocol for passion fruit-like nano-architectures composed by a silica shell embedding polymeric arrays of ultrasmall noble metal nanoparticles. These nano-architectures show interesting features for both oncology and catalysis. They avoid the issue of persistence in organism thanks to their fast biodegradation in renal clearable building blocks. Furthermore, their calcination results in yolk-shell structures composed by naked metal or alloy nanospheres shielded from aggregation by a silica shell.

Internal Morphologies of Cycled Li-Metal Electrodes Investigated by Nano-Scale Resolution X-ray Computed Tomography.

Science.gov (United States)

Frisco, Sarah; Liu, Danny X; Kumar, Arjun; Whitacre, Jay F; Love, Corey T; Swider-Lyons, Karen E; Litster, Shawn

2017-06-07

While some commercially available primary batteries have lithium metal anodes, there has yet to be a commercially viable secondary battery with this type of electrode. Research prototypes of these cells typically exhibit a limited cycle life before dendrites form and cause internal cell shorting, an occurrence that is more pronounced during high-rate cycling. To better understand the effects of high-rate cycling that can lead to cell failure, we use ex situ nanoscale-resolution X-ray computed tomography (nano-CT) with the aid of Zernike phase contrast to image the internal morphologies of lithium metal electrodes on copper wire current collectors that have been cycled at low and high current densities. The Li that is deposited on a Cu wire and then stripped and deposited at low current density appears uniform in morphology. Those cycled at high current density undergo short voltage transients to >3 V during Li-stripping from the electrode, during which electrolyte oxidation and Cu dissolution from the current collector may occur. The effect of temperature is also explored with separate cycling experiments performed at 5 and 33 °C. The resulting morphologies are nonuniform films filled with voids that are semispherical in shape with diameters ranging from hundreds of nanometers to tens of micrometers, where the void size distributions are temperature-dependent. Low-temperature cycling elicits a high proportion of submicrometer voids, while the higher-temperature sample morphology is dominated by voids larger than 2 μm. In evaluating these morphologies, we consider the importance of nonidealities during extreme charging, such as electrolyte decomposition. We conclude that nano-CT is an effective tool for resolving features and aggressive cycling-induced anomalies in Li films in the range of 100 nm to 100 μm.

The influence of nano silica particles on gamma-irradiation ageing of elastomers based on chlorosulphonated polyethylene and acrylonitrile butadiene rubber

Science.gov (United States)

Marković, G.; Marinović-Cincović, M.; Tanasić, Lj.; Jovanović, V.; Samaržija-Jovanović, S.; Vukić, N.; Budinski-Simendić, J.

2011-12-01

The goal of this work was to study gamma irradiation ageing of rubber blends based on acrylonitrile butadiene rubber (NBR) and chlorosulphonated polyethylene rubber (CSM) reinforced by silica nano particles. The NBR/CSM compounds (50: 50, w/w) filled with different content of filler (0-100 phr) were crosslinked by sulfur. The vulcanization characteristics were assessed using the rheometer with an oscillating disk. The vulcanizates were prepared in a hydraulic press. The obtained materials were exposed to the different irradiation doses (100, 200, 300 and 400 kGy). The mechanical properties (hardness, modulus at 100% elongation, tensile strength and elongation at break) and swelling numbers were assessed before and after gamma irradiation ageing.

A comprehensive study of soft magnetic materials based on FeSi spheres and polymeric resin modified by silica nanorods

International Nuclear Information System (INIS)

Strečková, M.; Füzer, J.; Kobera, L.; Brus, J.; Fáberová, M.; Bureš, R.; Kollár, P.; Lauda, M.; Medvecký, Ĺ.; Girman, V.; Hadraba, H.; Bat'ková, M.; Bat'ko, I.

2014-01-01

A novel soft magnetic composite (SMC) based on spherical FeSi particles precisely covered by hybrid phenolic resin was designed. The hybrid resin including silica nano-rods chemically incorporated into the phenolic polymer matrix was prepared by the modified sol–gel method. A chemical bridge connecting silica nano-rods with the base polymeric net was verified by FTIR, 13 C and 29 Si NMR spectroscopy, whereas the shape and size of silica nano-rods were determined by TEM. It is shown that the modification of polymeric resin by silica nano-rods generally leads to the improved thermal and mechanical properties of the final samples. The hybrid resin serves as a perfect insulating coating deposited on FeSi particles and the core–shell particles can be further compacted by standard powder metallurgy methods in order to prepare final samples for mechanical, electric and magnetic testing. SEM images evidence negligible porosity, uniform distribution of the hybrid resin around FeSi particles, as well as, dimensional shape stability of the final samples after thermal treatment. The hardness, flexural strength and density of the final samples are comparable to the sintered SMCs, but they simultaneously exhibit much higher specific resistivity along with only slightly lower coercivity and permeability. - Highlights: • Soft magnetic composites are designed for electrotechnical applications. • Electroinsulating layer consists of phenolic resin modified with silica nano-rods. • NMR, FTIR and DSC analysis is used to characterize hybrid resin. • Spherical Fe–Si particles covered by hybrid resin form a core–shell composite. • Mechanical, electrical and magnetic properties are described in detail

Carbon nano tubes embedded in polymer nano fibers

International Nuclear Information System (INIS)

Dror, Y.; Kedem, S.; Khalfin, R.L.; Paz, Y.; Cohenl, Y.; Salalha, Y.; Yarin, A.L.; Zussman, A.

2004-01-01

Full Text: The electro spinning process was used successfully to embed Multi-walled carbon nano tubes (MWCNTs) and single-walled carbon nano tubes (SWCNTs) in a matrix of poly(ethylene oxide) (PEO) forming composite nano fibers. Initial dispersion of SWCNTs in water was achieved by the use of an amphphilic alternating copolymer of styrene and sodium maleate. MWNT dispersion was achieved by ionic and nonionic surfactants. The distribution and conformation of the nano tubes in the nano fibers were studied by transmission electron microscopy (TEM). Oxygen plasma etching was used to expose the nano tubes within the nano fibers to facilitate direct observation. Nano tube alignment within the nano fibers was shown to depend strongly on the quality of the initial dispersions. Well-dispersed and separated nano tubes were embedded in a straight and aligned form while entangled non-separated nano tubes were incorporated as dense aggregates. X-ray diffraction demonstrated a high degree of orientation of the PEO crystals in the electro spun nano fibers with embedded SWCNTs, whereas incorporation of MVCNTs had a detrimental effect on the polymer orientation. Composite polymer nano fibers containing dispersed phases of nanometric TiO 2 particles and MWCNTs were also prepared electro spinning. In this case, the polymer matrix was poly(acrylonitrile) (PAN). The morphology and possible applications of these composite nano fibers will be discussed

Interphases, gelation, vitrification, porous glasses and the generalized Cauchy relation: epoxy/silica nanocomposites

Energy Technology Data Exchange (ETDEWEB)

Philipp, M; Mueller, U; Jimenez Rioboo, R J; Baller, J; Sanctuary, R; Krueger, J K [Laboratoire de Physique des Materiaux, University of Luxembourg, 162A avenue de la Faiencerie, L-1511 Luxembourg (Luxembourg); Possart, W [Fachbereich Werkstoffwissenschaften, Universitaet des Saarlandes, D-66123 Saarbruecken (Germany)], E-mail: martine.philipp@uni.lu

2009-02-15

The generalized Cauchy relation (gCR) of epoxy/silica nano-composites does not show either the chemically induced sol-gel transition or the chemically induced glass transition in the course of polymerization. Astonishingly, by varying the silica nanoparticles' concentration between 0 and 25 vol% in the composites, the Cauchy parameter A of the gCR remains universal and can be determined from the pure epoxy's elastic moduli. Air-filled porous silica glasses are considered as models for percolated silica particles. A longitudinal modulus versus density representation evidences the aforementioned transition phenomena during polymerization of the epoxy/silica nanocomposites. The existence of optically and mechanically relevant interphases is discussed.

Interphases, gelation, vitrification, porous glasses and the generalized Cauchy relation: epoxy/silica nanocomposites

International Nuclear Information System (INIS)

Philipp, M; Mueller, U; Jimenez Rioboo, R J; Baller, J; Sanctuary, R; Krueger, J K; Possart, W

2009-01-01

The generalized Cauchy relation (gCR) of epoxy/silica nano-composites does not show either the chemically induced sol-gel transition or the chemically induced glass transition in the course of polymerization. Astonishingly, by varying the silica nanoparticles' concentration between 0 and 25 vol% in the composites, the Cauchy parameter A of the gCR remains universal and can be determined from the pure epoxy's elastic moduli. Air-filled porous silica glasses are considered as models for percolated silica particles. A longitudinal modulus versus density representation evidences the aforementioned transition phenomena during polymerization of the epoxy/silica nanocomposites. The existence of optically and mechanically relevant interphases is discussed.

Electrochemically synthesized Si nano wire arrays and thermoelectric nano structures

International Nuclear Information System (INIS)

Khuan, N.I.; Ying, K.K.; Nur Ubaidah Saidin; Foo, C.T.

2012-01-01

Thermoelectric nano structures hold great promise for capturing and directly converting into electricity some vast amount of low-grade waste heats now being lost to the environment (for example from nuclear power plant, fossil fuel burning, automotive and household appliances). In this study, large-area vertically-aligned silicon nano wire (SiNW) arrays were synthesized in an aqueous solution containing AgNO 3 and HF on p-type Si (100) substrate by self-selective electroless etching process. The etching conditions were systematically varied in order to achieve different stages of nano wire formation. Diameters of the SiNWs obtained varied from approximately 50 to 200 nm and their lengths ranged from several to a few tens of μm. Te/ Bi 2 Te 3 -Si thermoelectric core-shell nano structures were subsequently obtained via galvanic displacement of SiNWs in acidic HF electrolytes containing HTeO 2 + and Bi 3+ / HTeO 2 + ions. The reactions were basically a nano-electrochemical process due to the difference in redox potentials between the materials. the surface-modified SiNWs of core-shell structures had roughened surface morphologies and therefore, higher surface-t-bulk ratios compared to unmodified SiNWs. They have potential applications in sensors, photovoltaic and thermoelectric nano devices. Growth study on the SiNWs and core-shell nano structures produced is presented using various microscopy, diffraction and probe-based techniques for microstructural, morphological and chemical characterizations. (Author)

Sub-micrometer waveguide for nano-optics

DEFF Research Database (Denmark)

Rottwitt, Karsten; Dyndgaard, Morten Glarborg; Andersen, Karin Nordström

2003-01-01

With the recent progress within the field of processing nano structures, there is an increasing interest in coupling light into such structures both for characterization of optical properties and new optical components. In this work we propose the use of a sub-micrometer planar waveguide for prob......With the recent progress within the field of processing nano structures, there is an increasing interest in coupling light into such structures both for characterization of optical properties and new optical components. In this work we propose the use of a sub-micrometer planar waveguide...... for probing the reflection of light against a nano structure. The planar waveguide is based on a silicon nitride core layer, surrounded by a silica cladding region. In our design we utilize this waveguide to couple light into a nano-structure....

A study of some fundamental physicochemical variables on the morphology of mesoporous silica nanoparticles MCM-41 type

Science.gov (United States)

Beltrán-Osuna, Ángela A.; Gómez Ribelles, José L.; Perilla, Jairo E.

2017-12-01

All variables affecting the morphology of mesoporous silica nanoparticles (MSN) should be carefully analyzed in order to truly tailored design their mesoporous structure according to their final use. Although complete control on MCM-41 synthesis has been already claimed, reproducibility and repeatability of results remain a big issue due to the lack of information reported in literature. Stirring rate, reaction volume, and system configuration (i.e., opened or closed reactor) are three variables that are usually omitted, making the comparison of product characteristics difficult. Specifically, the rate of solvent evaporation is seldom disclosed, and its influence has not been previously analyzed. These variables were systematically studied in this work, and they were proven to have a fundamental impact on final particle morphology. Hence, a high degree of circularity ( C = 0.97) and monodispersed particle size distributions were only achieved when a stirring speed of 500 rpm and a reaction scale of 500 mL were used in a partially opened system, for a 2 h reaction at 80 °C. Well-shaped spherical mesoporous silica nanoparticles with a diameter of 95 nm, a pore size of 2.8 nm, and a total surface area of 954 m2 g-1 were obtained. Final characteristics made this product suitable to be used in biomedicine and nanopharmaceutics, especially for the design of drug delivery systems.

Synthesis of new oxindole derivatives containing benzothiazole and thiazolidinone moieties using nano silica-bonded 5-n-propyl-octahydro-pyrimido[1,2-a]azepinium chloride (NSB-DBU) as catalyst

OpenAIRE

BAHARFAR, ROBABEH; SHARIATI, NARGES

2015-01-01

A facile one-pot synthesis of novel oxindole derivatives bearing benzothiazolylmethyl-2-thioxothiazolidin-4-one was accomplished via one-pot reaction of 5-oxoindolinylidene rhodanine-3-acetic acid derivatives, 2-aminothiophenol, and triphenyl phosphite in the presence of tetrabutylammonium bromide (TBAB) and nano silica-bonded 5-n-propyl-octahydro-pyrimido[1,2-a]azepinium chloride (NSB-DBU) as heterogeneous reusable nanocatalyst. The target compounds were obtained in excellent yields (...

Immobilization of mesoporous silica particles on stainless steel plates

International Nuclear Information System (INIS)

Pasqua, Luigi; Morra, Marco

2017-01-01

A preliminary study aimed to the nano-engineering of stainless steel surface is presented. Aminopropyl-functionalized mesoporous silica is covalently and electrostatically anchored on the surface of stainless steel plates. The anchoring is carried out through the use of a nanometric spacer, and two different spacers are proposed (both below 2 nm in size). The first sample is obtained by anchoring to the stainless steel amino functionalized, a glutaryl dichloride spacer. This specie forms an amide linkage with the amino group while the unreacted acyl groups undergo hydrolysis giving a free carboxylic group. The so-obtained functionalized stainless steel plate is used as substrate for anchoring derivatized mesoporous silica particles. The second sample is prepared using 2-bromo-methyl propionic acid as spacer (BMPA). Successively, the carboxylic group of propionic acid is condensed to the aminopropyl derivatization on the external surface of the mesoporous silica particle through covalent bond. In both cases, a continuous deposition (coating thickness is around 10 μm) is obtained, in fact, XPS data do not reveal the metal elements constituting the plate. The nano-engineering of metal surfaces can represent an intriguing opportunity for producing long-term drug release or biomimetic surface.

Immobilization of mesoporous silica particles on stainless steel plates

Energy Technology Data Exchange (ETDEWEB)

Pasqua, Luigi, E-mail: luigi.pasqua@unical.it [University of Calabria, Department of Environmental and Chemical Engineering (Italy); Morra, Marco, E-mail: mmorra@nobilbio.com [Via Valcastellana 26 (Italy)

2017-03-15

A preliminary study aimed to the nano-engineering of stainless steel surface is presented. Aminopropyl-functionalized mesoporous silica is covalently and electrostatically anchored on the surface of stainless steel plates. The anchoring is carried out through the use of a nanometric spacer, and two different spacers are proposed (both below 2 nm in size). The first sample is obtained by anchoring to the stainless steel amino functionalized, a glutaryl dichloride spacer. This specie forms an amide linkage with the amino group while the unreacted acyl groups undergo hydrolysis giving a free carboxylic group. The so-obtained functionalized stainless steel plate is used as substrate for anchoring derivatized mesoporous silica particles. The second sample is prepared using 2-bromo-methyl propionic acid as spacer (BMPA). Successively, the carboxylic group of propionic acid is condensed to the aminopropyl derivatization on the external surface of the mesoporous silica particle through covalent bond. In both cases, a continuous deposition (coating thickness is around 10 μm) is obtained, in fact, XPS data do not reveal the metal elements constituting the plate. The nano-engineering of metal surfaces can represent an intriguing opportunity for producing long-term drug release or biomimetic surface.

Encapsulation of antigen-loaded silica nanoparticles into microparticles for intradermal powder injection.

Science.gov (United States)

Deng, Yibin; Mathaes, Roman; Winter, Gerhard; Engert, Julia

2014-10-15

Epidermal powder immunisation (EPI) is being investigated as a promising needle-free delivery methods for vaccination. The objective of this work was to prepare a nanoparticles-in-microparticles (nano-in-micro) system, integrating the advantages of nanoparticles and microparticles into one vaccine delivery system for epidermal powder immunisation. Cationic mesoporous silica nanoparticles (MSNP-NH2) were prepared and loaded with ovalbumin as a model antigen. Loading was driven by electrostatic interactions. Ovalbumin-loaded silica nanoparticles were subsequently formulated into sugar-based microparticles by spray-freeze-drying. The obtained microparticles meet the size requirement for EPI. Confocal microscopy was used to demonstrate that the nanoparticles are homogeneously distributed in the microparticles. Furthermore, the silica nanoparticles in the dry microparticles can be re-dispersed in aqueous solution showing no aggregation. The recovered ovalbumin shows integrity compared to native ovalbumin. The present nano-in-micro system allows (1) nanoparticles to be immobilized and finely distributed in microparticles, (2) microparticle formation and (3) re-dispersion of nanoparticles without subsequent aggregation. The nanoparticles inside microparticles can (1) adsorb proteins to cationic shell/surface voids in spray-dried products without detriment to ovalbumin stability, (2) deliver antigens in nano-sized modes to allow recognition by the immune system. Copyright © 2014 Elsevier B.V. All rights reserved.

Synthesis and new structure shaping mechanism of silica particles formed at high pH

International Nuclear Information System (INIS)

Zhang, Henan; Zhao, Yu; Akins, Daniel L.

2012-01-01

For the sol–gel synthesis of silica particles under high pH catalytic conditions (pH>12) in water/ethanol solvent, we have deduced that the competing dynamics of chemical etching and sol–gel process can explain the types of silica particles formed and their morphologies. We have demonstrated that emulsion droplets that are generated by adding tetraethyl orthosilicate (TEOS) to a water–ethanol solution serve as soft templates for hollow spherical silica (1–2 μm). And if the emulsion is converted by the sol–gel process, one finds that suspended solid silica spheres of diameter of ∼900 nm are formed. Moreover, several other factors are found to play fundamental roles in determining the final morphologies of silica particles, such as by variation of the pH (in our case, using OH – ) to a level where condensation dominates; by changing the volume ratios of water/ethanol; and using an emulsifier (specifically, CTAB) - Graphical abstract: “Local chemical etching” and sol–gel process have been proposed to interpret the control of morphologies of silica particles through varying initial pHs in syntheses. Highlights: ► Different initial pHs in our syntheses provides morphological control of silica particles. ► “Local chemical etching” and sol–gel process describes the formation of silica spheres. ► The formation of emulsions generates hollow silica particles.

Fabrication of amorphous silica nanowires via oxygen plasma treatment of polymers on silicon

Science.gov (United States)

Chen, Zhuojie; She, Didi; Chen, Qinghua; Li, Yanmei; Wu, Wengang

2018-02-01

We demonstrate a facile non-catalytic method of fabricating silica nanowires at room temperature. Different polymers including photoresists, parylene C and polystyrene are patterned into pedestals on the silicon substrates. The silica nanowires are obtained via the oxygen plasma treatment on those pedestals. Compared to traditional strategies of silica nanowire fabrication, this method is much simpler and low-cost. Through designing the proper initial patterns and plasma process parameters, the method can be used to fabricate various regiment nano-scale silica structure arrays in any laboratory with a regular oxygen-plasma-based cleaner or reactive-ion-etching equipment.

Luminescent Eosin Y–SiO{sub 2} hybrid nano and microrods prepared by sol–gel template method

Energy Technology Data Exchange (ETDEWEB)

Secu, M., E-mail: msecu@infim.ro [National Institute for Materials Physics, P.O. Box MG-7, Bucharest–Magurele, 077125 (Romania); Secu, C.E.; Sima, M.; Negrea, R.F.; Bartha, C. [National Institute for Materials Physics, P.O. Box MG-7, Bucharest–Magurele, 077125 (Romania); Dinescu, M.; Damian, V. [National Institute for Laser, Plasma and Radiation, P.O. Box MG-36, Bucharest–Magurele 077125 (Romania)

2013-11-15

Sol–gel chemistry within the pores of a polycarbonate template membrane was used for the preparation of Eosin Y–SiO{sub 2} hybrid nano- and microrods, using tetraethylorthosilicate [TEOS, Si(OC{sub 2}H{sub 5}){sub 4}] as the precursor in the presence of trifluoroacetic acid (TFA) catalyst. The ethanolic solution of Eosin-Y was added to the silica sol to trap dye molecules inside the SiO{sub 2} gel network during the gelation. Structural and morphological characterization using scanning electron microscopy (SEM) and luminescence microscopy have shown the formation of rods with 200 nm and 1.2 μm diameter and about 30 μm length, exhibiting luminescence properties. Spectroscopic characterization has shown that the luminescence is due to Eosin-Y molecule in the xerogel porous network, surrounded by a solvation shell given mainly by the water. -- Highlights: • Sol–gel template method was used to prepare Eosin Y–SiO{sub 2} hybrid rods-type structures. • Morphological characterization has shown nano- and microrods with luminescent properties. • Luminescence is due to Eosin-Y molecule surrounded by a solvation shell given by water.

Thickness and morphology of polyelectrolyte coatings on silica surfaces before and after protein exposure studied by atomic force microscopy

Energy Technology Data Exchange (ETDEWEB)

Haselberg, Rob, E-mail: r.haselberg@vu.nl [Biomolecular Analysis, Utrecht University, Universiteitsweg 99, 3584 CG Utrecht (Netherlands); AIMMS Division of BioMolecular Analysis, VU University Amsterdam, de Boelelaan 1083, 1081 HV Amsterdam (Netherlands); Flesch, Frits M. [Biomolecular Analysis, Utrecht University, Universiteitsweg 99, 3584 CG Utrecht (Netherlands); Boerke, Arjan [Department of Biochemistry and Cell Biology, Utrecht University, Yalelaan 2, 3508 TD Utrecht (Netherlands); Somsen, Govert W. [Biomolecular Analysis, Utrecht University, Universiteitsweg 99, 3584 CG Utrecht (Netherlands); AIMMS Division of BioMolecular Analysis, VU University Amsterdam, de Boelelaan 1083, 1081 HV Amsterdam (Netherlands)

2013-05-24

Graphical abstract: -- Highlights: •Atomic force microscopy is used to characterize polyelectrolyte coatings. •Coating procedure leads to nm-thick layers on a silica surface. •Polyelectrolyte coatings effectively prevent protein adsorption. •AFM provides the high resolution to investigate these thin films. •AFM results support earlier findings obtained with capillary electrophoresis. -- Abstract: Analyte–wall interaction is a significant problem in capillary electrophoresis (CE) as it may compromise separation efficiencies and migration time repeatability. In CE, self-assembled polyelectrolyte multilayer films of Polybrene (PB) and dextran sulfate (DS) or poly(vinylsulfonic acid) (PVS) have been used to coat the capillary inner wall and thereby prevent analyte adsorption. In this study, atomic force microscopy (AFM) was employed to investigate the layer thickness and surface morphology of monolayer (PB), bilayer, (PB-DS and PB-PVS), and trilayer (PB-DS-PB and PB-PVS-PB) coatings on glass surfaces. AFM nanoshaving experiments providing height distributions demonstrated that the coating procedures led to average layer thicknesses between 1 nm (PB) and 5 nm (PB-DS-PB), suggesting the individual polyelectrolytes adhere flat on the silica surface. Investigation of the surface morphology of the different coatings by AFM revealed that the PB coating does not completely cover the silica surface, whereas full coverage was observed for the trilayer coatings. The DS-containing coatings appeared on average 1 nm thicker than the corresponding PVS-containing coatings, which could be attributed to the molecular structure of the anionic polymers applied. Upon exposure to the basic protein cytochrome c, AFM measurements showed an increase of the layer thickness for bare (3.1 nm) and PB-DS-coated (4.6 nm) silica, indicating substantial protein adsorption. In contrast, a very small or no increase of the layer thickness was observed for the PB and PB-DS-PB coatings

Copper-doped silica cuprous sulfate: A highly efficient heterogeneous nano-catalyst for one-pot three-component synthesis of 1-H-2-substituted benzimidazoles from 2-bromoanilines, aldehydes, and [bmim]N3

Directory of Open Access Journals (Sweden)

Somayeh Behrouz

2018-03-01

Full Text Available A facile and highly efficient one-pot three-component synthesis of 1-H-2-substituted benzimidazole derivatives from readily available substrates catalyzed by copper-doped silica cuprous sulfate (CDSCS is described. In this method, treatment of diverse 2-bromoanilines, aldehydes, and [bmim]N3 in DMF at 110 °C in the presence of CDSCS as a highly efficient heterogeneous nano-catalyst affords the corresponding 1-H-2-substituted benzimidazoles in good to excellent yields. The CDSCS is an inexpensive and stable nano-catalyst that could be simply prepared, recovered and reused for many consecutive reaction runs without significant loss of its activity.

Effect of Nano-TiC Dispersed Particles and Electro-Codeposition Parameters on Morphology and Structure of Hybrid Ni/TiC Nanocomposite Layers.

Science.gov (United States)

Benea, Lidia; Celis, Jean-Pierre

2016-04-06

This research work describes the effect of dispersed titanium carbide (TiC) nanoparticles into nickel plating bath on Ni/TiC nanostructured composite layers obtained by electro-codeposition. The surface morphology of Ni/TiC nanostructured composite layers was characterized by scanning electron microscopy (SEM). The composition of coatings and the incorporation percentage of TiC nanoparticles into Ni matrix were studied and estimated by using energy dispersive X-ray analysis (EDX). X-ray diffractometer (XRD) has been applied in order to investigate the phase structure as well as the corresponding relative texture coefficients of the composite layers. The results show that the concentration of nano-TiC particles added in the nickel electrolyte affects the inclusion percentage of TiC into Ni/TiC nano strucured layers, as well as the corresponding morphology, relative texture coefficients and thickness indicating an increasing tendency with the increasing concentration of nano-TiC concentration. By increasing the amount of TiC nanoparticles in the electrolyte, their incorporation into nickel matrix also increases. The hybrid Ni/nano-TiC composite layers obtained revealed a higher roughness and higher hardness; therefore, these layers are promising superhydrophobic surfaces for special application and could be more resistant to wear than the pure Ni layers.

Effect of Nano-TiC Dispersed Particles and Electro-Codeposition Parameters on Morphology and Structure of Hybrid Ni/TiC Nanocomposite Layers

Directory of Open Access Journals (Sweden)

Lidia Benea

2016-04-01

Full Text Available This research work describes the effect of dispersed titanium carbide (TiC nanoparticles into nickel plating bath on Ni/TiC nanostructured composite layers obtained by electro-codeposition. The surface morphology of Ni/TiC nanostructured composite layers was characterized by scanning electron microscopy (SEM. The composition of coatings and the incorporation percentage of TiC nanoparticles into Ni matrix were studied and estimated by using energy dispersive X-ray analysis (EDX. X-ray diffractometer (XRD has been applied in order to investigate the phase structure as well as the corresponding relative texture coefficients of the composite layers. The results show that the concentration of nano-TiC particles added in the nickel electrolyte affects the inclusion percentage of TiC into Ni/TiC nano strucured layers, as well as the corresponding morphology, relative texture coefficients and thickness indicating an increasing tendency with the increasing concentration of nano-TiC concentration. By increasing the amount of TiC nanoparticles in the electrolyte, their incorporation into nickel matrix also increases. The hybrid Ni/nano-TiC composite layers obtained revealed a higher roughness and higher hardness; therefore, these layers are promising superhydrophobic surfaces for special application and could be more resistant to wear than the pure Ni layers.

Silane effects on the surface morphology and abrasion resistance of transparent SiO2/UV-curable resin nano-composites

International Nuclear Information System (INIS)

Hsiang, Hsing-I.; Chang, Yu-Lun; Chen, Chi-Yu; Yen, Fu-Su

2011-01-01

Transparent ultraviolet curable nano-composite coatings consisting of nano-sized SiO 2 and acrylate resin have been developed to improve the abrasion resistance of organic polymers. The nano-sized SiO 2 particles were surface-modified using various amounts of 3-methacryloxypropyltrimethoxysilane. The 3-methacryloxypropyltrimethoxysilane concentration effects on the surface morphology and abrasion resistance of the transparent SiO 2 /ultraviolet-curable resin nano-composites were investigated using scanning electron microscopy, atomic force microscopy, and ultraviolet-visible spectrophotometer. The results showed that as the 3-methacryloxypropyltrimethoxysilane/SiO 2 weight ratio increased from 0.2 to 0.6, the dispersion, compatibility and cross-linking density between the 3-methacryloxypropyltrimethoxysilane-modified SiO 2 particles and acrylate resin were improved, leading to an increase in abrasion resistance. However, as the 3-methacryloxypropyltrimethoxysilane/SiO 2 weight ratio was increased to 1.5, the additional 3-methacryloxypropyltrimethoxysilane may exceed that needed to fill the pores with the probability of SiO 2 nano-particles existing on the coating surface was lower than that for samples with a 3-methacryloxypropyltrimethoxysilane/SiO 2 weight ratio of 0.6. This produced a decrease in abrasion resistance.

Effects of confinement in meso-porous silica and carbon nano-structures; Etude des effets de confinement dans la silice mesoporeuse et dans certaines nanostructures carbonees

Energy Technology Data Exchange (ETDEWEB)

Leon, V

2006-07-15

Physico-chemical properties of materials can be strongly modified by confinement because of the quantum effects that appear at such small length scales and also because of the effects of the confinement itself. The aim of this thesis is to show that both the nature of the confining material and the size of the pores and cavities have a strong impact on the confined material. We first show the effect of the pore size of the host meso-porous silica on the temperature of the solid-solid phase transition of silver selenide, a semiconducting material with enhanced magnetoresistive properties under non-stoichiometric conditions. Narrowing the pores from 20 nm to 2 nm raises the phase transition temperature from 139 C to 146 C. This result can be explained by considering the interaction between the confining and confined materials as a driving force. The effects of confinement are also studied in the case of hydrogen and deuterium inside cavities of organized carbon nano-structures. The effects that appear in the adsorption/desorption cycles are much stronger with carbon nano-horns as the host material than with C60 pea-pods and single-walled carbon nano-tubes. (author)

Plasmonic properties and enhanced fluorescence of gold and dye-doped silica nanoparticle aggregates

Science.gov (United States)

Green, Nathaniel Scott

scattering. Our aim is to promote heteroaggregation with functionalized silica nanoparticles while minimizing homoaggregation of silica-silica or gold-gold species. Reproducible production of multiple gold nanospheres about a dye-doped silica nanoparticle should lead to dramatic fluorescence brightness enhancements in solution. Gold nanorods can potentially be used to establish radiationless energy transfer between hetero dye-doped silica nanoparticles via gold nanorod plasmon mediated FRET by aggregating two different dye-doped silica nanoparticles preferentially at opposite ends of the nanorod. End-cap binding is accomplished by tuning the strength of gold binding ligands that functionalize the surface of the silica nanoparticles. The gold nanorod can then theoretically serve as a waveguide by employing the longitudinal plasmon as a non-radiative energy transfer agent between the two different fluorophores, giving rise to a new ultrafast signaling paradigm. Heteroaggregation of dye-doped silica nanoparticles and gold nanorods can be potentially employed to as nano waveguides. Construction and aggregation of functionalized silica and gold nano-materials provides an opportunity to advance the field of fluorescence. The synthesis of gold nano-particles allows control over their size and shape, which give rise to useful optical and electronic properties. Silica nanoparticles provide a framework allowing control over a requisite distance for increasing beneficial and deceasing non-radiative dye-metal interactions as well fluorophore protection. Our aim is to take advantage of fine-tuned synthetic control of functionalized nanomaterials to realize the great potential of solution based metal-enhanced fluorescence for future applications.

Effectiveness of amorphous silica encapsulation technology on welding fume particles and its impact on mechanical properties of welds

International Nuclear Information System (INIS)

Wang, Jun; Wu, Chang-Yu; Franke, Gene

2014-01-01

Highlights: • A novel welding shielding gas containing a silica precursor. • Up to 76% of the welding fume particles encapsulated in an amorphous silica layer. • No statistical difference between different types of welds in mechanical tests. • Can potentially reduce the toxicity of welding fume particles. - Abstract: Stainless steel welding generates nano-sized fume particles containing toxic metals which may cause serious health effects upon inhalation. The objective of this study was to investigate the effectiveness of an amorphous silica encapsulation (ASE) technology by evaluating its silica coating efficiency (SCE), particle morphology, and its impact on the weld’s mechanical properties. Tetramethylsilane (TMS) added to the welding shielding gas decomposed at the high-temperature arc zone to enable the silica coating. Collected welding fume particles were digested by two acid mixtures with different degrees of silica solubility, and the measured mass differences in the digests were used to determine the SCE. The SCEs were around 48–64% at the low and medium primary shielding gas flow rates. The highest SCE of 76% occurred at the high shielding gas flow rate (30 Lpm) with a TMS carrier gas flow of 0.64 Lpm. Transmission electron microscopy (TEM) images confirmed the amorphous silica layer on the welding fume particles at most gas flow rates, as well as abundant stand-alone silica particles formed at the high gas flow rate. Metallography showed that welds from the baseline and from the ASE technology were similar except for a tiny crack found in one particular weld made with the ASE technology. Tensile tests showed no statistical difference between the baseline and the ASE welds. All the above test results confirm that welding equipment retrofitted with the ASE technology has the potential to effectively address the toxicity problem of welding fume particles without affecting the mechanical properties of the welds

Influence of Nano sized Silicon Oxide on the Luminescent Properties of Zn O Nanoparticles

International Nuclear Information System (INIS)

Shvalagin, V.; Grodziuk, G.; Kurmach, M.; Granchak, V.; Sarapulova, O.; Sherstiuk, V.

2016-01-01

For practical use of nano sized zinc oxide as the phosphor its luminescence quantum yields should be maximized. The aim of this work was to enhance luminescent properties of Zn O nanoparticles and obtain high-luminescent Zn O/SiO 2 composites using simpler approaches to colloidal synthesis. The luminescence intensity of zinc oxide nanoparticles was increased about 3 times by addition of silica nano crystals to the source solutions during the synthesis of Zn O nanoparticles. Then the quantum yield of luminescence of the obtained Zn O/SiO 2 composites is more than 30%. Such an impact of silica is suggested to be caused by the distribution of Zn O nano crystals on the surface of silica, which reduces the probability of separation of photo generated charges between the zinc oxide nanoparticles of different sizes, and as a consequence, there is a significant increase of the luminescence intensity of Zn O nanoparticles. This way of increasing nano-Zn O luminescence intensity facilitates its use in a variety of devices, including optical ultraviolet and visible screens, luminescent markers, antibacterial coatings, luminescent solar concentrators, luminescent inks for security printing, and food packaging with abilities of informing consumers about the quality and safety of the packaged product.

Synthesis of nano-Au doped SiO2 aerogels by seeding method

International Nuclear Information System (INIS)

Ren Hongbo; Wan Xiaobo; Zhang Lin; Du Aiming; Xiu Peng

2006-01-01

A new approach to synthesize gold nano cluster doped aerogel on the basis of surface-catalyzed reduction of metal ions was described. Au nano particles were formed in a silica aerogel matrix by hydroxylamine seeding method of reducing gold ions on the silica colloidal surface. Subsequently, the pH value of system was adjusted to about 7-8, the gel formed within 2 h. After aging for 2 d, the gels were washed in aceton, and then dried supercritically (from CO 2 ) to yield aerogels. The reduction process was attributed to hydroxylamine-induced surface catalysis. Au clusters in the aerogel monoliths were characterized with optical adsorption, transmission electron microscopy. These techniques have shown the cluster size and weight content in the aerogels. Brunauer-emmett-teller surface area measurements show that the specific surface area of silica aerogels and doped aerogels are higher than 800 m 2 /g. (authors)

Toughened and machinable glass matrix composites reinforced with graphene and graphene-oxide nano platelets

Czech Academy of Sciences Publication Activity Database

Porwal, H.; Tatarko, Peter; Grasso, S.; Hu, Ch.; Boccaccini, A. R.; Dlouhý, Ivo; Reece, M.J.

2013-01-01

Roč. 14, č. 5 (2013), Art.N. 055007 ISSN 1468-6996 EU Projects: European Commission(XE) 264526 - GLACERCO Institutional support: RVO:68081723 Keywords : silica * graphene/graphene-oxide nano platelets * nano composites * mechanical properties * sintering Subject RIV: JI - Composite Materials Impact factor: 2.613, year: 2013

Silica nanoparticles containing 159-Gadolinium as potential system for cancer treatment

International Nuclear Information System (INIS)

Oliveira, Andre Felipe de; Ferreira, Tiago Hilario; Sousa, Edesia Martins Barros de; Lacerda, Marco Aurelio

2013-01-01

Ordered silica nanoparticles are compounds highly organized which have very interesting textural characteristics, such as high thermal stability, well defined pore size, narrow size distribution and high area surface. Among the various types of nano materials ordered, the SBA-16 have a meso structure that can be considered very interesting due to the fact of the arrangement of mesoporous (tri dimensional as a cage) and spherical morphology, which make it in a promising material for a range of bioapplications such as incorporation of drugs and radioisotopes. In this study Gadodiamide® (Omniscan-General Electric Healthcare Company), a frequently non-ionic gadolinium complex contrasting used in MRI's was incorporated in the silica matrix SBA-16 as a carrier. From this gadolinium it is possible to obtain the isotope 159 Gd by neutron irradiation, wherein the isotope 158 Gd captures a neutron and becomes 159 Gd [ 15 '8Gd(n,c) 1 '5 9 Gd]. The 159 Gd is a beta (endpoint energy of 970.6 keV) and gamma (main energy: 363.54 keV) emitter with a half-life of 18.59 hours. These characteristics are similar to that of other isotopes already used in nuclear medicine such as 90 Y. In this work, the 158 Gd incorporated in the Gd-silica was activated by the neutron flux generated by the cyclotron located in the Centro de Desenvolvimento da Tecnologia Nuclear (CDTN) during the production of the 18 FDG. Atomic emission spectroscopy (ICP-AES) and infrared spectroscopy (FTIR) were used to confirm the presence of the gadolinium complex in the silica matrix. The antitumor activity of the complex after the irradiation was evaluated through cytotoxicity assay with T98 cell lines derived from a human glioblastoma multiform tumor. (author)

Development of vapor deposited silica sol-gel particles for use as a bioactive materials system.

Science.gov (United States)

Snyder, Katherine L; Holmes, Hallie R; VanWagner, Michael J; Hartman, Natalie J; Rajachar, Rupak M

2013-06-01

Silica-based sol-gel and bioglass materials are used in a variety of biomedical applications including the surface modification of orthopedic implants and tissue engineering scaffolds. In this work, a simple system for vapor depositing silica sol-gel nano- and micro-particles onto substrates using nebulizer technology has been developed and characterized. Particle morphology, size distribution, and degradation can easily be controlled through key formulation and manufacturing parameters including water:alkoxide molar ratio, pH, deposition time, and substrate character. These particles can be used as a means to rapidly modify substrate surface properties, including surface hydrophobicity (contact angle changes >15°) and roughness (RMS roughness changes of up to 300 nm), creating unique surface topography. Ions (calcium and phosphate) were successfully incorporated into particles, and induced apatitie-like mineral formation upon exposure to simulated body fluid Preosteoblasts (MC3T3) cultured with these particles showed up to twice the adhesivity within 48 h when compared to controls, potentially indicating an increase in cell proliferation, with the effect likely due to both the modified substrate properties as well as the release of silica ions. This novel method has the potential to be used with implants and tissue engineering materials to influence cell behavior including attachment, proliferation, and differentiation via cell-material interactions to promote osteogenesis. Copyright © 2012 Wiley Periodicals, Inc.

Combinatorial Nano-Bio Interfaces.

Science.gov (United States)

Cai, Pingqiang; Zhang, Xiaoqian; Wang, Ming; Wu, Yun-Long; Chen, Xiaodong

2018-06-08

Nano-bio interfaces are emerging from the convergence of engineered nanomaterials and biological entities. Despite rapid growth, clinical translation of biomedical nanomaterials is heavily compromised by the lack of comprehensive understanding of biophysicochemical interactions at nano-bio interfaces. In the past decade, a few investigations have adopted a combinatorial approach toward decoding nano-bio interfaces. Combinatorial nano-bio interfaces comprise the design of nanocombinatorial libraries and high-throughput bioevaluation. In this Perspective, we address challenges in combinatorial nano-bio interfaces and call for multiparametric nanocombinatorics (composition, morphology, mechanics, surface chemistry), multiscale bioevaluation (biomolecules, organelles, cells, tissues/organs), and the recruitment of computational modeling and artificial intelligence. Leveraging combinatorial nano-bio interfaces will shed light on precision nanomedicine and its potential applications.

Study of Ion Transport Behaviour in (PVA-NH4I):SIO2 Nano Composite Polymer Electrolyte

Science.gov (United States)

Tripathi, Mridula; Trivedi, Shivangi; Upadhyay, Ruby; Singh, Markandey; Pandey, N. D.; Pandey, Kamlesh

2013-07-01

Development and characterization of Poly vinyl alcohol (PVA) based nano composite polymer electrolytes comprising of (PVA-NH4I):SiO2 is reported. Sol-gel derived silica powder of nano dimension has been used as ceramic filler for development of nano composite electrolyte. Formation of nano composites, change in the structural and microscopic properties of the system have been investigated by X-ray differaction, SEM and conductivity.

Physicochemical characterizations of nano-palm oil fuel ash

Energy Technology Data Exchange (ETDEWEB)

Rajak, Mohd Azrul Abdul, E-mail: azrulrajak88@gmail.com [Department of Chemistry, Faculty of Science, Universiti Teknologi Malaysia, 81310 UTM Johor Bahru (Malaysia); Preparatory Centre of Science and Technology, Universiti Malaysia Sabah, Jalan UMS, 88400, Kota Kinabalu, Sabah (Malaysia); Majid, Zaiton Abdul, E-mail: zaiton@kimia.fs.utm.my [Department of Chemistry, Faculty of Science, Universiti Teknologi Malaysia, 81310 UTM Johor Bahru (Malaysia); Ismail, Mohammad [Department of Structure and Material, Faculty of Civil Engineering, Universiti Teknologi Malaysia, 81310 UTM Johor Bahru (Malaysia)

2015-07-22

Palm Oil Fuel Ash (POFA) is known as a good supplementary cementing material due to its siliceous-rich content. The application of nanotechnology in the pozzolanic materials could invent new functions in the efficiency of physical and chemical properties of materials. Thus, the present study aims to generate nano-sized POFA and characterize the physicochemical properties of nano-palm oil fuel ash (nPOFA). The nPOFA was prepared by mechanically grinding micro POFA using a high intensity ball milling for 6 hours. The physicochemical properties of nPOFA were characterized via X-Ray Fluoresence (XRF), Scanning Emission microscopy- Energy Dispersive X-Ray (SEM-EDX), Transmission Electron Microscope (TEM) and X-Ray Diffraction (XRD). The particle size of nPOFA acquired from TEM analysis was in the range of 20 nm to 90 nm, while the average crystallite size calculated from XRD diffractogram was 61.5 nm. The resulting nPOFA has a BET surface area of 145.35 m{sup 2}/g, which is more than 85% increment in surface area compared to micro-sized POFA. The morphology and elemental studies showed the presence of spherical as well as irregularly shaped and fine nPOFA particles contains with high silicon content. The presence of α-quartz as the major phase of the nPOFA was identified through XRD analysis. The study concludes that nPOFA has the potential as a supplementary cementing material due to the high silica content, high surface area and the unique behaviors of nano-structured particles.

Physicochemical characterizations of nano-palm oil fuel ash

Science.gov (United States)

Rajak, Mohd Azrul Abdul; Majid, Zaiton Abdul; Ismail, Mohammad

2015-07-01

Palm Oil Fuel Ash (POFA) is known as a good supplementary cementing material due to its siliceous-rich content. The application of nanotechnology in the pozzolanic materials could invent new functions in the efficiency of physical and chemical properties of materials. Thus, the present study aims to generate nano-sized POFA and characterize the physicochemical properties of nano-palm oil fuel ash (nPOFA). The nPOFA was prepared by mechanically grinding micro POFA using a high intensity ball milling for 6 hours. The physicochemical properties of nPOFA were characterized via X-Ray Fluoresence (XRF), Scanning Emission microscopy- Energy Dispersive X-Ray (SEM-EDX), Transmission Electron Microscope (TEM) and X-Ray Diffraction (XRD). The particle size of nPOFA acquired from TEM analysis was in the range of 20 nm to 90 nm, while the average crystallite size calculated from XRD diffractogram was 61.5 nm. The resulting nPOFA has a BET surface area of 145.35 m2/g, which is more than 85% increment in surface area compared to micro-sized POFA. The morphology and elemental studies showed the presence of spherical as well as irregularly shaped and fine nPOFA particles contains with high silicon content. The presence of α-quartz as the major phase of the nPOFA was identified through XRD analysis. The study concludes that nPOFA has the potential as a supplementary cementing material due to the high silica content, high surface area and the unique behaviors of nano-structured particles.

Controlled Synthesis of Manganese Dioxide Nano structures via a Facile Hydrothermal

International Nuclear Information System (INIS)

Pang, R.S.C.; Chin, S.F.; Ye, Ch. Ling

2012-01-01

Manganese dioxide nano structures with controllable morphological structures and crystalline phases were synthesized via a facile hydrothermal route at low temperatures without using any templates or surfactants. Both the aging duration and aging temperatures were the main synthesis parameters used to influence and control the rate of morphological and structural evolution of MnO 2 nano structures. MnO 2 nano structures comprise of spherical nano particulate agglomerates and highly amorphous in nature were formed at lower temperature and/or short aging duration. In contrast, MnO 2 nano structures of sea-urchin-like and nano rods-like morphologies and nanocrystalline in nature were prepared at the combined higher aging temperatures and longer aging durations. These nano structures underwent notable phase transformation from d-MnO 2 to a-MnO 2 upon prolonged hydrothermal aging duration and exhibited accelerated rate of phase transformation at higher aging temperature.

Nucleation of polystyrene latex particles in the presence of gamma-methacryloxypropyltrimethoxysilane: functionalized silica particles.

Science.gov (United States)

Bourgeat-Lami, Elodie; Insulaire, Mickaelle; Reculusa, Stéphane; Perro, Adeline; Ravaine, Serge; Duguet, Etienne

2006-02-01

Silica/polystyrene nanocomposite particles with different morphologies were synthesized through emulsion polymerization of styrene in the presence of silica particles previously modified by gamma-methacryloxypropyltrimethoxysilane (MPS). Grafting of the silane molecule was performed by direct addition of MPS to the aqueous silica suspension in the presence of an anionic surfactant under basic conditions. The MPS grafting density on the silica surface was determined using the depletion method and plotted against the initial MPS concentration. The influence of the MPS grafting density, the silica particles size and concentration and the nature of the surfactant on the polymerization kinetics and the particles morphology was investigated. When the polymerization was performed in the presence of an anionic surfactant, transmission electron microscopy images showed the formation of polymer spheres around silica for MPS grafting densities lower than typically 1 micromole x m(-2) while the conversion versus time curves indicated a strong acceleration effect under such conditions. In contrast, polymerizations performed in the presence of a larger amount of MPS moieties or in the presence of a non ionic emulsifier resulted in the formation of "excentered" core-shell morphologies and lower polymerization rates. The paper identifies the parameters that allow to control particles morphology and polymerization kinetics and describes the mechanism of formation of the nanocomposite colloids.

Patchy silica-coated silver nanowires as SERS substrates

International Nuclear Information System (INIS)

Hunyadi Murph, Simona E.; Murphy, Catherine J.

2013-01-01

We report a class of core–shell nanomaterials that can be used as efficient surface-enhancement Raman scattering (SERS) substrates. The core consists of silver nanowires, prepared through a chemical reduction process, that are used to capture 4-mercaptobenzoic acid (4-MBA), a model analyte. The shell was prepared through a modified Stöber method and consists of patchy or full silica coats. The formation of silica coats was monitored via transmission electron microscopy, UV–visible spectroscopy, and phase-analysis light-scattering for measuring effective surface charge. Surprisingly, the patchy silica-coated silver nanowires are better SERS substrate than silver nanowires; nanomolar concentration of 4-MBA can be detected. In addition, “nano-matryoshka” configurations were used to quantitate/explore the effect of the electromagnetic field at the tips of the nanowire (“hot spots”) in the Raman scattering experiment.

Patchy silica-coated silver nanowires as SERS substrates

Energy Technology Data Exchange (ETDEWEB)

Hunyadi Murph, Simona E.; Murphy, Catherine J.

2013-05-08

We report a class of core-shell nanomaterials that can be used as efficient surface-enhancement Raman scattering (SERS) substrates. The core consists of silver nanowires, prepared through a chemical reduction process, that are used to capture 4- mercaptobenzoic acid (4-MBA), a model analyte. The shell was prepared through a modified Stöber method and consists of patchy or full silica coats. The formation of silica coats was monitored via transmission electron microscopy, UV-visible spectroscopy and phase-analysis light scattering for measuring effective surface charge. Surprisingly, the patchy silica coated silver nanowires are better SERS substrate than silver nanowires; nanomolar concentration of 4-MBA can be detected. In addition, “nano-matryoshka” configurations were used to quantitate/explore the effect of the electromagnetic field at the tips of the nanowire (“hot spots”) in the Raman scattering experiment.

A flexible, bolaamphiphilic template for mesoporous silicas.

Science.gov (United States)

Yuen, Alexander K L; Heinroth, Falk; Ward, Antony J; Masters, Anthony F; Maschmeyer, Thomas

2013-08-28

A novel symmetrical bolaamphiphile, containing two N-methylimidazolium head-groups bridged by a 32-methylene linker, was synthesized and characterized. A variety of mesoporous silicas was prepared using the bolaamphiphile as a "soft template". The effects of absolute surfactant concentration and synthesis conditions upon the morphologies of these silicas were investigated. For a given surfactant concentration, particle morphology; pore size; and pore ordering were modified through control of the template to silica-precursor ratio and synthesis conditions. Observed morphologies included: lenticular core-shell nanoparticles and decorticated globules, truncated hexagonal plates, and sheets. In all cases the mesopores are aligned along the shortest axis of the nanomaterial. Decorticated materials displayed surface areas of up to 1200 m(2) g(-1) and pore diameters (D(BJH)) of 24-28 Å. Small-angle X-ray diffraction and transmission electron microscopy measurements revealed that the majority of the materials has elliptical pores arranged in rectangular lattices (c2mm). Adoption of this symmetry group is a result of the template aggregate deformation from a regular hexagonal phase of cylindrical rods to a ribbon phase under the synthetic conditions.

Controlling morphology and crystallite size of Cu(In0.7Ga0.3)Se2 nano-crystals synthesized using a heating-up method

International Nuclear Information System (INIS)

Hsu, Wei-Hsiang; Hsiang, Hsing-I; Chia, Chih-Ta; Yen, Fu-Su

2013-01-01

CuIn 0.7 Ga 0.3 Se 2 (CIGS) nano-crystals were successfully synthesized via a heating-up process. The non-coordinating solvent (1-octadecene) and selenium/cations ratio effects on the crystalline phase and crystallite size of CIGS nano-crystallites were investigated. It was observed that the CIGS nano-crystallite morphology changed from sheet into spherical shape as the amount of 1-octadecene addition was increased. CIGS nano-crystals were obtained in 9–20 nm sizes as the selenium/cations ratio increased. These results suggest that the monomer reactivity in the solution can be adjusted by changing the solvent type and selenium/cations ratio, hence affecting the crystallite size and distribution. - Graphical abstract: CuIn 0.7 Ga 0.3 Se 2 (CIGS) nano-crystals were successfully synthesized via a heating-up process in this study. The super-saturation in the solution can be adjusted by changing the OLA/ODE ratio and selenium/cation ratio.

Quantitative analysis of silica aerogel-based thermal insulation coatings

DEFF Research Database (Denmark)

Kiil, Søren

2015-01-01

containing intact hollow glass or polymer spheres showed that silica aerogel particles are more efficient in an insulation coating than hollow spheres. In a practical (non-ideal) comparison, the ranking most likely cannot be generalized. A parameter study demonstrates how the model can be used, qualitatively......A mathematical heat transfer model for a silica aerogel-based thermal insulation coating was developed. The model can estimate the thermal conductivity of a two-component (binder-aerogel) coating with potential binder intrusion into the nano-porous aerogel structure. The latter is modelled using...... a so-called core–shell structure representation. Data from several previous experimental investigations with silica aerogels in various binder matrices were used for model validation. For some relevant cases with binder intrusion, it was possible to obtain a very good agreement between simulations...

Multi-scale analysis of the effect of nano-filler particle diameter on the physical properties of CAD/CAM composite resin blocks.

Science.gov (United States)

Yamaguchi, Satoshi; Inoue, Sayuri; Sakai, Takahiko; Abe, Tomohiro; Kitagawa, Haruaki; Imazato, Satoshi

2017-05-01

The objective of this study was to assess the effect of silica nano-filler particle diameters in a computer-aided design/manufacturing (CAD/CAM) composite resin (CR) block on physical properties at the multi-scale in silico. CAD/CAM CR blocks were modeled, consisting of silica nano-filler particles (20, 40, 60, 80, and 100 nm) and matrix (Bis-GMA/TEGDMA), with filler volume contents of 55.161%. Calculation of Young's moduli and Poisson's ratios for the block at macro-scale were analyzed by homogenization. Macro-scale CAD/CAM CR blocks (3 × 3 × 3 mm) were modeled and compressive strengths were defined when the fracture loads exceeded 6075 N. MPS values of the nano-scale models were compared by localization analysis. As the filler size decreased, Young's moduli and compressive strength increased, while Poisson's ratios and MPS decreased. All parameters were significantly correlated with the diameters of the filler particles (Pearson's correlation test, r = -0.949, 0.943, -0.951, 0.976, p CAD/CAM CR blocks can be enhanced by loading silica nanofiller particles of smaller diameter. CAD/CAM CR blocks by using smaller silica nano-filler particles have a potential to increase fracture resistance.

Impact of the Excitation Source and Plasmonic Material on Cylindrical Active Coated Nano-Particles

Directory of Open Access Journals (Sweden)

Richard W. Ziolkowski

2011-09-01

Full Text Available Electromagnetic properties of cylindrical active coated nano-particles comprised of a silica nano-cylinder core layered with a plasmonic concentric nano-shell are investigated for potential nano-sensor applications. Particular attention is devoted to the near-field properties of these particles, as well as to their far-field radiation characteristics, in the presence of an electric or a magnetic line source. A constant frequency canonical gain model is used to account for the gain introduced in the dielectric part of the nano-particle, whereas three different plasmonic materials (silver, gold, and copper are employed and compared for the nano-shell layers.

Nano hydroxyapatite-blasted titanium surface affects pre-osteoblast morphology by modulating critical intracellular pathways.

Science.gov (United States)

Bezerra, Fábio; Ferreira, Marcel R; Fontes, Giselle N; da Costa Fernandes, Célio Jr; Andia, Denise C; Cruz, Nilson C; da Silva, Rodrigo A; Zambuzzi, Willian F

2017-08-01

Although, intracellular signaling pathways are proposed to predict the quality of cell-surface relationship, this study addressed pre-osteoblast behavior in response to nano hydroxyapatite (HA)-blasted titanium (Ti) surface by exploring critical intracellular pathways and pre-osteoblast morphological change. Physicochemical properties were evaluated by atomic force microscopy (AFM) and wettability considering water contact angle of three differently texturized Ti surfaces: Machined (Mac), Dual acid-etching (DAE), and nano hydroxyapatite-blasted (nHA). The results revealed critical differences in surface topography, impacting the water contact angle and later the osteoblast performance. In order to evaluate the effect of those topographical characteristics on biological responses, we have seeded pre-osteoblast cells on the Ti discs for up to 4 h and subjected the cultures to biological analysis. First, we have observed pre-osteoblasts morphological changes resulting from the interaction with the Ti texturized surfaces whereas the cells cultured on nHA presented a more advanced spreading process when compared with the cells cultured on the other surfaces. These results argued us for analyzing the molecular machinery and thus, we have shown that nHA promoted a lower Bax/Bcl2 ratio, suggesting an interesting anti-apoptotic effect, maybe explained by the fact that HA is a natural element present in bone composition. Thereafter, we investigated the potential effect of those surfaces on promoting pre-osteoblast adhesion and survival signaling by performing crystal violet and immunoblotting approaches, respectively. Our results showed that nHA promoted a higher pre-osteoblast adhesion supported by up-modulating FAK and Src activations, both signaling transducers involved during eukaryotic cell adhesion. Also, we have shown Ras-Erk stimulation by the all evaluated surfaces. Finally, we showed that all Ti-texturing surfaces were able to promote osteoblast differentiation

Metal Oxide Nano structures: Synthesis, Properties, and Applications

International Nuclear Information System (INIS)

Xu, L. H.; Patil, D. S.; Yang, J.; Xiao, J.

2015-01-01

In recent years, nano structured materials have attracted wide attention due to their fascinating optical and electrical properties, which make these materials potentially suitable for applications in electronics, optics, photonics, and sensors. Some metal oxides show a wide variety of morphologies such as nano wires, nano rods, nano tubes, nano rings, and nano belts. Synthesis and investigation of these metal-oxide nano structures are beneficial not only for understanding the fundamental phenomena in low dimensional systems, but also for developing new-generation nano devices with high performance.

In Vitro Toxicity of Naturally Occurring Silica Nanoparticles in C1 Coal 
in Bronchial Epithelial Cells

Directory of Open Access Journals (Sweden)

Guangjian LI

2012-10-01

Full Text Available Background and objective China’s Xuan Wei County in Yunnan Province have the world’s highest incidence of lung cancer in nonsmoking women-20 times higher than the rest of China. Previous studies showed, this high lung cancer incidence may be associated with the silica particles embedded in the production combustion from the C1 coal. The aim of this study is to separate the silica particles from production combustion from the C1 bituminous coal in Xuan Wei County of Yunnan Province, and study in vitro toxicity of naturally occurring silica particles on BEAS-2B. Methods ①Separating the silica particles from combustion products of C1 bituminous coal by physical method, observing the morphology by Scanning Electron Microscope, analysis elements by SEM-EDX, observed the single particle morphology by Transmission Electron Microscope, analyed its particle size distribution by Laser particle size analyzer, the surface area of silica particles were determined by BET nitrogen adsorption analysis; ②Cell viability of the experimental group (silica; naturally occurring, control group (silica; industrial produced and crystalline silica was detected by assay used the 3-(4,5-dimethylthiazol-2-yl-2,5-diphenyltetrazolium bromide (MTT method, and the reactive oxygen species (ROS, lactate dehydrogenase (LDH were determined after 24 h-72 h exposed to these particles. Results ①The physical method can separate silica particles from production combustion from the C1 bituminous coal, which have different size, and from 30 nm to 120 nm particles accounted for 86.8%, different morphology, irregular surface area and containing trace of aluminum, calcium and iron and other elements; ②Under the same concentration, the experiment group have higher toxicity on BEAS-2B than control groups. Conclusion ①Physical method can separate silica particles from production combustion from the C1 bituminous coal and not change the original morphology and containing trace; �

Photovoltaic's silica-rich waste sludge as supplementary cementitious material (SCM)

Energy Technology Data Exchange (ETDEWEB)

Quercia, G., E-mail: g.quercia@tue.nl [Materials innovation institute (M2i), Mekelweg 2, P.O. Box 5008, 2600 GA Delft (Netherlands); Eindhoven University of Technology, Department of the Built Environment, P.O. Box 513, 5600 MB Eindhoven (Netherlands); Putten, J.J.G. van der [Eindhoven University of Technology, Department of the Built Environment, P.O. Box 513, 5600 MB Eindhoven (Netherlands); Hüsken, G. [BAM Federal Institute for Materials Research and Testing, Unter den Eichen 87, D-12205 Berlin (Germany); Brouwers, H.J.H. [Eindhoven University of Technology, Department of the Built Environment, P.O. Box 513, 5600 MB Eindhoven (Netherlands)

2013-12-15

Waste sludge, a solid recovered from wastewater of photovoltaic-industries, composes of agglomerates of nano-particles like SiO{sub 2} and CaCO{sub 3}. This sludge deflocculates in aqueous solutions into nano-particles smaller than 1 μm. Thus, this sludge constitutes a potentially hazardous waste when it is improperly disposed. Due to its high content of amorphous SiO{sub 2}, this sludge has a potential use as supplementary cementitious material (SCM) in concrete. In this study the main properties of three different samples of photovoltaic's silica-rich waste sludge (nSS) were physically and chemically characterized. The characterization techniques included: scanning electron microscopy (SEM), X-ray energy dispersive spectroscopy (EDS), X-ray diffraction (XRD), nitrogen physical adsorption isotherm (BET method), density by Helium pycnometry, particle size distribution determined by laser light scattering (LLS) and zeta-potential measurements by dynamic light scattering (DLS). In addition, a dispersability study was performed to design stable slurries to be used as liquid additives for the concrete production on site. The effects on the hydration kinetics of cement pastes by the incorporation of nSS in the designed slurries were determined using an isothermal calorimeter. A compressive strength test of standard mortars with 7% of cement replacement was performed to determine the pozzolanic activity of the waste nano-silica sludge. Finally, the hardened system was fully characterized to determine the phase composition. The results demonstrate that the nSS can be utilized as SCM to replace portion of cement in mortars, thereby decreasing the CO{sub 2} footprint and the environmental impact of concrete. -- Highlights: •Three different samples of PV nano-silica sludge (nSS) were fully characterized. •nSS is composed of agglomerates of nano-particles like SiO{sub 2} and CaCO{sub 3}. •Dispersability studies demonstrated that nSS agglomerates are broken to nano

An investigation on morphology and mechanical properties of HDPE/nanoclay/nanoCaCO_3 ternary nanocomposites

International Nuclear Information System (INIS)

Garmabi, Hamid; Tabari, Seyed Emad Alavi; Javadi, Azizeh; Behrouzi, Hormoz; Hosseini, Gholamabbas

2016-01-01

Ternary Nanocomposites of high-density polyethylene (HDPE) containing two types of nano particles, a layered organoclay (Closite 15A) and a spherical nano Calcium Carbonate (CaCO_3), with various compositions were prepared using melt mixing. Maleic anhydride grafted polyethylene (MA-g-PE) was used to enhance the dispersion of nanofillers and better interface adhesion. Three different levels of nanoclay (1, 3, 5 wt. %), CaCO_3 (6, 8, 10 wt. %) and MA-g-PE (3, 6, 9 wt. %) were used. The mixing was done in two steps: First a concentrated masterbatch of nanoparticles in HPDE and MA-g-PE was prepared using an internal mixer and then melt-mixing of nanocomposites was done in a lab scale co-rotating twin screw extruder. The morphology of samples was studied using Scanning Electron Microscopy (SEM) and mechanical properties were evaluated using tensile and impact tests. According to the SEM micrographs, nanofillers were well dispersed in the HDPE matrix and XRD patterns showed the intercalation of nanoclay layers too. Generally using the layered nanoclay can enhance the tensile modulus while the use of spherical nano CaCO_3 results into improved toughness. It was found that co-incorporation of these two types of nanofillers, leads to improve the stiffness and minimize the reduction of impact strength, simultaneously.

An effective approach to synthesis of poly(methyl methacrylate)/silica nanocomposites

International Nuclear Information System (INIS)

Ding Xuefeng; Wang Zichen; Han Dongxue; Zhang Yuanjian; Shen Yanfei; Wang Zhijuan; Niu Li

2006-01-01

A novel synthetic route for nearly monodispersed poly(methyl methacrylate)/SiO 2 composite particles (PMSCP) is reported. Silica nanoparticles modified with oleic acid were used as 'seeds'. Methyl methacrylate (MMA) monomer was copolymerized with oleic acid via in situ emulsion polymerization, in the presence of an initiator; it resulted finally in the formation of composites with core-shell morphology. The composite particles were examined by transmission electron microscopy (TEM), scanning electron microscopy (SEM), x-ray photoelectron spectroscopy (XPS) and thermogravimetric analysis (TGA). The number of silica particles inside the composite particles increases with an increase in the silica concentration. The effect of grafted silica concentration on the morphology of PMSCP is also reported in detail. It was found by thermogravimetric analysis that PMSCP show a potential application for fire retardance

Effect of plasticizer and fumed silica on ionic conductivity behaviour

Indian Academy of Sciences (India)

The effect of addition of propylene carbonate (PC) and nano-sized fumed silica on the ionic conductivity behaviour of proton conducting polymer electrolytes containing different concentrations of hexafluorophosphoric acid (HPF6) in polyethylene oxide (PEO) has been studied. The addition of PC results in an increase in ...

a study on silica sand quality in yazaram and mugulbu deposits

African Journals Online (AJOL)

ENGR. G A DUVUNA

A STUDY ON SILICA SAND QUALITY IN YAZARAM AND MUGULBU ... the lowest percentage of silica content of 77.60% and the grain morphology was found to be angular with specific ..... things.com/articles/glass colouring.html, accessed.

Preparation of nano-biomaterials with Leptolyngbia foveolarum and heavy metal biosorption by free and immobilized algal cells

International Nuclear Information System (INIS)

Toncheva-Panova, T.; Pouneva, I.; Sholeva, M.; Chernev, G.

2010-01-01

Using the sol-gel procedure nano-biomaterials with incorporation of Leptolyngbia foveolarum in the silica matrix were manufactured. The immobilization of algal cells was confirmed with Scanning Electron Microscopy (SEM) investigations and photos. Observation of nano-biomaterials with Atomic Force Microscopy (AFM) shows nanostructure with well-defined nanounits and their aggregates. The potential of the Antarctic isolate L. foveolarum for sorption of Cu 2+ and Cd 2+ was studied by incubation of free algal cells and those immobilized in nano-biomaterials in the salts solutions of the two heavy metals. The rest of the heavy metal was determined with inductively coupled plasma atomic emission spectrometer (ICP-AES). It was established that the heavy metal biosorption capacity demonstrated by the free Leptolyngbia cells was retained after their incorporation in the nano-matrices. Free cells as well as embedded in silica nano-matrix sequestered the two heavy metals with greater affinity for copper. The highest binding capacity, 76% of the initial Cu 2+ concentration possessed nano-biomaterials with incorporated vegetative L. foveolarum cells, compared to 68% of free cells. For cadmium the degree of biosorption was lower - 35% by free cells and 30.2% by those incorporated in the biocer. (authors)

Hybrid thin films derived from UV-curable acrylate-modified waterborne polyurethane and monodispersed colloidal silica

Directory of Open Access Journals (Sweden)

C. H. Yang

2012-01-01

Full Text Available Hybrid thin films containing nano-sized inorganic domains were synthesized from UV-curable acrylate-modified waterborne polyurethane (WPU-AC and monodispersed colloidal silica with coupling agent. The coupling agent, 3-(trimethoxysilylpropyl methacrylate (MSMA, was bonded onto colloidal silica first, and then mixed with WPU-AC to form a precursor solution. This precursor was spin coated, dried and UV-cured to generate the hybrid films. The silica content in the hybrid thin films was varied from 0 to 30 wt%. Experimental results showed the aggregation of silica particles in the hybrid films. Thus, the silica domain in the hybrid films was varied from 30 to 50 nm by the different ratios of MSMAsilica to WPU-AC. The prepared hybrid films from the crosslinked WPU-AC/MSMA-silica showed much better thermal stability and mechanical properties than pure WPU-AC.

Optical properties of Cu{sub 2}S nano-hollow cactus arrays with different morphologies

Energy Technology Data Exchange (ETDEWEB)

Li, Liqiang, E-mail: liliqiang3672603@163.com [School of Physics, Shangqiu Normal University, Shangqiu 476000 (China); Hong, Cuilan [School of Chemistry, Shangqiu Normal University, Shangqiu 476000 (China); Zhang, Wenxing; Chen, Wencong; Li, Peng [School of Physics, Shangqiu Normal University, Shangqiu 476000 (China)

2015-07-05

Highlights: • The light absorption ability of CNHC is enhanced as the decrease of the thorn diameter. • The band gap of CNHC can be adjusted by changing their morphologies. • The CNHC with different morphologies are less sensitive to the light incident angles. • CNHC will reduce trouble of moving around solar cell panels when they were used in the photovoltaics. - Abstract: In this study, a series of Cu{sub 2}S nano-hollow cactus arrays (CNHC) with varying morphologies is prepared by a two-step process including electrodeposition and the solid–gas reaction method. The structure of the arrays is characterized by scanning electron microscopy, X-ray diffraction, transmission electron microscopy, X-ray photoelectron spectroscopy, and Raman spectroscopy; while, their light absorption performance is investigated by diffuse reflectance and photoluminescence spectroscopy. The “thorns” of the CNHC are single-crystal Cu{sub 2}S semiconductors, and the band gap of the CNHC can be adjusted by changing their morphology, where the light absorption ability of the array is enhanced from 82% to 93% as the thorn diameter decreases from 1500 to 163 nm. All of the different CNHC morphologies exhibit little sensitivity to the incident angle of the light. For example, the light absorption of the CNHC with a thorn diameter of 430 nm only decreases by 5% as the incident angle increases from 0° to 45°. This shows the potential of the CNHC for use in solar energy applications, where its insensitivity to the angle of the incident light will reduce the necessity of adjusting the angle of solar cell panels using CNHC in the photovoltaics.

Reduction of microbial biofilm formation using hydrophobic nano ...

African Journals Online (AJOL)

2015-04-03

Apr 3, 2015 ... ISSN 1816-7950 (On-line) = Water SA Vol. ... nano-silica coating on cooling tower fill material. Irfan Türetgen1*. 1Istanbul University, Faculty of Science, Department of Biology, Istanbul .... The study was conducted in a 100-ℓ polypropylene lab- ... out using a contact angle goniometer with deionized water at.

Controlled generation of silver nanocolloid in amorphous silica materials

International Nuclear Information System (INIS)

Gil, C.; Garcia-Heras, M.; Carmona, N.; Villages, M. A.

2004-01-01

Amorphous silica-based materials bulk and superficially doped with silver nano colloids were prepared. Bulk doped glasses were obtained by conventional melting and doped monolithic slabs by sol-gel. Superficially doped glasses were obtained by ion-exchange and doped coatings by sol-gel. The samples were characterised by TEM and UV-VIS spectrometry. Depending on the composition, the silver incorporation process, and the thermal treatments, several colourings were obtained. By controlling these parameters, metallic silver nano colloids can be generated in the matrices studied. Colloids aggregation and growing up depends on the matrix nature and on the experimental process carried out. (Author) 10 refs

Incorporation mode effect of Nano-silica on the rheological and mechanical properties of cementitious pastes and cement mortars

Science.gov (United States)

Safi, B.; Aknouche, H.; Mechakra, H.; Aboutaleb, D.; Bouali, K.

2018-04-01

Previous research indicates that the inclusion of nanosilica (NS) modifies the properties of the fresh and hardened state, compared to the traditional mineral additions. NS decreases the setting times of the cement mortar compared to silica fume (SF) and reduce of required water while improving the cohesion of the mixtures in the fresh state. Some authors estimate that the appropriate percentage of Nano-silica should be small (1 to 5% by weight) because of difficulties caused by agglomeration to particles during mixing, while others indicate that 10% by weight, if adjustments are made to the formulation to avoid an excess of self-drying and micro cracks that could impede strength. For this purpose, the present work aim to see the effect of the introduction mode of the nanosilica on the rheological and physic mechanical properties of cement mortars. In this study, NS was used either powdered with cement or in solution with the superplasticizer (Superplasticizer doped in nanosilica). Results show that the use of nanosilica powder (replacing cement on the one hand) has a negative influence on the rheological parameters and the rheological behavior of cementitious pastes. However, the introduction of nanosilica in solution in the superplasticizer (SP) was significantly improved the rheological parameters and the rheological behavior of cementitious pastes. Indeed, more the dosage of NS-doped SP increases more the shear stress and viscosities of the cementitious pastes become more fluid and manageable. A significant reduction of shear stress and plastic viscosity were observed that due to the increase in superplasticizer. A dosage of 1.5% NS-doped SP gave adequate fluidity and the shear rate was lower.

Catalytic Activity and Photophysical Properties of Biomolecules Immobilized on Mesoporous Silica

DEFF Research Database (Denmark)

Ikemoto, Hideki

Mesoporous silicas, based on Santa Barbara Amorphous-15 (SBA-15), with different morphology, structure, pore size and functional groups have been synthesized. Two metalloenzymes and a photosynthetic membrane protein were immobilized on or confined in the pores of the mesoporous silicas to prepare...

Impact behavior of f-silica and amine terminated polybutadiene co-acrylonitrile rubber modified novolac epoxy/Kevlar nanocomposites

Science.gov (United States)

Kavita, Pal, Vijayeta; Tiwari, R. K.

2018-05-01

In the present work, nano-fumed silica treated with 3-Glycidoxypropyl trimethoxy silane (f-silica) was used as a nanoreinforcement in the fabrication of amine terminated polybutadiene co-acrylonitrile rubber (ATBN) modified Kevlar/epoxy based nanocomposites. Nanocomposites with different f-silica loading (0, 0.5, 1.0 and 2.0 wt. %) and having same ATBN (10 wt. %) were made and characterized by Izod impact test for evaluating impact strength values. All the nanocomposites showed better impact strength than neat Kevlar/novolac epoxy based composite.

Investigation of the correlation between dielectric function, thickness and morphology of nano-granular ZnO very thin films

Energy Technology Data Exchange (ETDEWEB)

Gilliot, Mickaël, E-mail: mickael.gilliot@univ-reims.fr [Laboratoire d' Ingénierie et Sciences des Matériaux, Université de Reims Champagne-Ardenne (France); Hadjadj, Aomar [Laboratoire d' Ingénierie et Sciences des Matériaux, Université de Reims Champagne-Ardenne (France); Martin, Jérôme [Laboratoire de Nanotechnologie et d' Instrumentation Optique, Université de Technologie de Troyes (France)

2015-12-31

Thin nano-granular ZnO layers were prepared using a sol–gel synthesis and spin-coating deposition process with a thickness ranging between 20 and 120 nm. The complex dielectric function (ϵ) of the ZnO film was determined from spectroscopic ellipsometry measurements. Up to a critical thickness close to 60 nm, the magnitude of both the real and the imaginary parts of ϵ rapidly increases and then slowly tends to values closer to the bulk ZnO material. This trend suggests a drastic change in the film porosity at both sides of this critical thickness, due to the pre-heating and post-crystallization processes, as confirmed by additional characterization of the structure and the morphology of the ZnO films. - Highlights: • c-Axis oriented ZnO thin films were grown with different morphological states. • The morphology and structures are controlled by controlling the thickness. • The optical properties are correlated to morphological evolution. • Two growth behaviors and property evolutions are identified around a critical thickness.

Electrodeposition of ZnO nano-wires lattices with a controlled morphology; Electrodepot de reseaux de nanofils de ZnO a morphologie controlee

Energy Technology Data Exchange (ETDEWEB)

Elias, J.; Tena-Zaera, R.; Katty, A.; Levy-Clement, C. [Centre National de la Recherche Scientifique (CNRS), Lab. de Chimie Metallurgique des Terres Rares, UPR 209, 94 - Thiais (France)

2006-07-01

In this work, it is shown that the electrodeposition is a changeable low cost method which allows, according to the synthesis conditions, to obtain not only plane thin layers of ZnO but different nano-structures too. In a first part, are presented the formation conditions of a compact thin layer of nanocrystalline ZnO electrodeposited on a conducing glass substrate. This layer plays a buffer layer role for the deposition of a lattice of ZnO nano-wires. The step of nano-wires nucleation is not only determined by the electrochemical parameters but by the properties of the buffer layer too as the grain sizes and its thickness. In this context, the use of an electrodeposition method in two steps allows to control the nano-wires length and diameter and their density. The morphology and the structural and optical properties of these nano-structures have been analyzed by different techniques as the scanning and transmission electron microscopy, the X-ray diffraction and the optical spectroscopy. These studies show that ZnO nano-structures are formed of monocrystalline ZnO nano-wires, presenting a great developed surface and a great optical transparency in the visible. These properties make ZnO a good material for the development of nano-structured photovoltaic cells as the extremely thin absorber cells (PV ETA) or those with dye (DSSC) which are generally prepared with porous polycrystalline TiO{sub 2}. Its replacement by a lattice of monocrystalline ZnO nano-wires allows to reduce considerably the number of grain boundaries and in consequence to improve the transport of the electrons. The results are then promising for the PV ETA cells with ZnO nano-wires. (O.M.)

Characterization of Polycaprolactone and Rice Husk Silica Composite (PCL-SiO2) by E-Spinning to Apply Supporter for Drug Release

Science.gov (United States)

Song, Sinae; Hilonga, Askwar; Taik Kim, Hee

2018-03-01

Polycaprolactone (PCL) is an interesting material to apply biomedical field owing to its biodegradability and biocompatibility which is suitable for a specific site with longer healing times. Blending the polymer with other materials has degradation property improved with the effective and economic method. This study was conducted to fabricate supporter based on Polycaprolactone and Rice husk silica (PCL-SiO2) by using electrospinning. Nano-porous silica in the composite was synthesized from rice husk having properties of economic, eco-friendly and high surface area. It drew to enhance the amount of drug loading in the carrier. Electrospinning technique is used to fabricate fibrous component by optimization condition obtained from previous mechanical properties experiments. Release experiment was carried out by the degree of dye absorbance at 544nm by ultraviolet–visible spectroscopy, the RhB in SiO2 alternative drug for modelling of drug release was released for 1 ~ 20 days at 37°C in phosphate buffer. Furthermore, the Mechanical property was confirmed by DSC, TGA. Morphology and degree of biodegradation were shown as SEM images and EDS.

Toughening Mechanisms in Silica-Filled Epoxy Nanocomposites

Science.gov (United States)

Patel, Binay S.

Epoxies are widely used as underfill resins throughout the microelectronics industry to mechanically couple and protect various components of flip-chip assemblies. Generally rigid materials largely surround underfill resins. Improving the mechanical and thermal properties of epoxy resins to better match those of their rigid counterparts can help extend the service lifetime of flip-chip assemblies. Recently, researchers have demonstrated that silica nanoparticles are effective toughening agents for lightly-crosslinked epoxies. Improvements in the fracture toughness of silica-filled epoxy nanocomposites have primarily been attributed to two toughening mechanisms: particle debonding with subsequent void growth and matrix shear banding. Various attempts have been made to model the contribution of these toughening mechanisms to the overall fracture energy observed in silica-filled epoxy nanocomposites. However, disparities still exist between experimental and modeled fracture energy results. In this dissertation, the thermal, rheological and mechanical behavior of eight different types of silica-filled epoxy nanocomposites was investigated. Each nanocomposite consisted of up to 10 vol% of silica nanoparticles with particle sizes ranging from 20 nm to 200 nm, with a variety of surface treatments and particle structures. Fractographical analysis was conducted with new experimental approaches in order to accurately identify morphological evidence for each proposed toughening mechanism. Overall, three major insights into the fracture behavior of real world silica-filled epoxy nanocomposites were established. First, microcracking was observed as an essential toughening mechanism in silica-filled epoxy nanocomposites. Microcracking was observed on the surface and subsurface of fractured samples in each type of silica-filled epoxy nanocomposite. The additional toughening contribution of microcracking to overall fracture energy yielded excellent agreement between experimental

Gold nanostructure-integrated silica-on-silicon waveguide for the detection of antibiotics in milk and milk products

Science.gov (United States)

Ozhikandathil, Jayan; Badilescu, Simona; Packirisamy, Muthukumaran

2012-10-01

Antibiotics are extensively used in veterinary medicine for the treatment of infectious diseases. The use of antibiotics for the treatment of animals used for food production raised the concern of the public and a rapid screening method became necessary. A novel approach of detection of antibiotics in milk is reported in this work by using an immunoassay format and the Localized Surface Plasmon Resonance property of gold. An antibiotic from the penicillin family that is, ampicillin is used for testing. Gold nanostructures deposited on a glass substrate by a novel convective assembly method were heat-treated to form a nanoisland morphology. The Au nanostructures were functionalized and the corresponding antibody was absorbed from a solution. Solutions with known concentrations of antigen (antibiotics) were subsequently added and the spectral changes were monitored step by step. The Au LSPR band corresponding to the nano-island structure was found to be suitable for the detection of the antibody antigen interaction. The detection of the ampicillin was successfully demonstrated with the gold nano-islands deposited on glass substrate. This process was subsequently adapted for the integration of gold nanostructures on the silica-on-silicon waveguide for the purpose of detecting antibiotics.

Template preparation of twisted nanoparticles of mesoporous silica

Institute of Scientific and Technical Information of China (English)

Kui Niu; Zhongbin Ni; Chengwu Fu; Tatsuo Kaneko; Mingqing Chen

2011-01-01

Optical isomers of N-lauroyl-L-(or-D-) alanine sodium salt {C12-L-(or-D-)AlaS} surfactants were used for the preparation of mesoporous silica nanoparticles with a twisted hexagonal rod-like morphology. Thermogravimetric analysis (TGA) was used to determine the temperature for template removal. Circular dichroism (CD) spectra of the surfactant solution with various compositions illustrated the formation and supramolecular assembly of protein-like molecular architecture leading to formation of twisted nanoparticles. Scanning electron microscopy (SEM),high-resolution transmission electron microscopy (HRTEM)and X-ray powder diffraction (XRD) patterns of these as-synthesized mesoporous silica confirmed that the twisted morphology of these nanoparticles was closely related to the supramolecular-assembled complex of amino acid surfactants.

Enhancement of flame retardancy and water repellency properties of cotton fabrics using silanol based nano composites.

Science.gov (United States)

Mohamed, Amina L; El-Sheikh, Manal A; Waly, Ahmed I

2014-02-15

Environmental concerns related to fluorinated and organophosphorus compounds led to a consideration of the methods for imparting flame retardancy and water/oil repellency to textiles. A simple and facile method for fabricating the cotton fabric with superhydrophobicity and flame retardancy is described in the present work. Complex coating with amino-functionalized silica nano-particles on epoxy-functionalized cotton accompanied with ZnO nano-particles coating are carried out. In This context, new preparation techniques were used to prepare both aminated silica and ZnO nano-particles. The particle size was investigated using Transition Electron Microscope (TEM) and the chemical structure was investigated using FT-IR analysis and other analytical techniques. Cotton was functionalized with epoxy and carboxyl via grafting cotton with nano-emulsion consisted of mixture of glycidyl methacrylate (GMA) and acrylic acid (AA), and then treated for functional finishing through conventional pad-dry-cure method. The treated fabrics showed good water repellency and excellent flame retardant properties as determined by the standard test methods. Copyright © 2013 Elsevier Ltd. All rights reserved.

Degradability and Clearance of Silicon, Organosilica, Silsesquioxane, Silica Mixed Oxide, and Mesoporous Silica Nanoparticles

KAUST Repository

Croissant, Jonas G.

2017-01-13

The biorelated degradability and clearance of siliceous nanomaterials have been questioned worldwide, since they are crucial prerequisites for the successful translation in clinics. Typically, the degradability and biocompatibility of mesoporous silica nanoparticles (MSNs) have been an ongoing discussion in research circles. The reason for such a concern is that approved pharmaceutical products must not accumulate in the human body, to prevent severe and unpredictable side-effects. Here, the biorelated degradability and clearance of silicon and silica nanoparticles (NPs) are comprehensively summarized. The influence of the size, morphology, surface area, pore size, and surface functional groups, to name a few, on the degradability of silicon and silica NPs is described. The noncovalent organic doping of silica and the covalent incorporation of either hydrolytically stable or redox- and enzymatically cleavable silsesquioxanes is then described for organosilica, bridged silsesquioxane (BS), and periodic mesoporous organosilica (PMO) NPs. Inorganically doped silica particles such as calcium-, iron-, manganese-, and zirconium-doped NPs, also have radically different hydrolytic stabilities. To conclude, the degradability and clearance timelines of various siliceous nanomaterials are compared and it is highlighted that researchers can select a specific nanomaterial in this large family according to the targeted applications and the required clearance kinetics.

Effect of Molecular Weight on the Properties of Liquid Epoxidized Natural Rubber Acrylate (LENRA)/ Silica Hybrid Composites

International Nuclear Information System (INIS)

Eda Yuhana Ariffin; Azizan Ahmad; Dahlan Mohd; Mahathir Mohamed

2011-01-01

This paper reports on the effect of molecular weight on the morphological and mechanical properties of liquid epoxidized natural rubber acrylate (LENRA)/ silica hybrid composites prepared by sol-gel technique. The sol-gel reaction was conducted at different concentration of tetraethyl orthosilicate (TEOS), used as a precursor of silica. TEOS were introduced in 10, 20, 30, 40 and 50 parts per hundred rubber (phr) in the composites. Two different molecular weights of ENR were used to study the effect of molecular weight on the mechanical and morphological properties of the compounds. These compounds were cured by ultraviolet (UV) irradiation. The mechanical properties were studied through pendulum hardness and scratch tests. Higher molecular weight of ENR showed better mechanical properties than lower molecular weight. Transmission electron microscope was used to determine the silica size and to study the distribution and dispersion of the silica particles. High molecular weight showed greater distribution and dispersion of silica particles with diameter of 13 - 256 nm. Morphological and mechanical properties of LENRA/ silica hybrid composites were improved by using high molecular weight of ENR. (author)

Application of Super-Amphiphilic Silica-Nanogel Composites for Fast Removal of Water Pollutants

Directory of Open Access Journals (Sweden)

Ayman M. Atta

2016-10-01

Full Text Available This work first reports the preparation of super-amphiphilic silica-nanogel composites to reduce the contact angle of water to increase the diffusion of pollutant into adsorbents. In this respect, the silica nanoparticles were encapsulated into nanogels based on ionic and nonionic polyacrylamides by dispersion polymerization technique. The morphologies and the dispersion stability of nanogel composites were investigated to clarify the ability of silica-nanogel composites to adsorb at different interfaces. The feasibility of silica polyacrylamide nanogel composites to act as a high-performance adsorbent for removal of methylene blue (MB dye and heavy metals (Co2+ and Ni2+ from aqueous solution was investigated. The surface tension, contact angle, average pore size, and zeta potential of the silica-nanogel composites have been evaluated. The MB dye and heavy metal adsorption capacity achieved Qmax = 438–387 mg/g which is considerably high. The adsorption capacity results are explained from the changes in the morphology of the silica surfaces as recorded from scanning electron microscopy (SEM.

Pozzolanic Reactivity of Silica Fume and Ground Rice Husk Ash as Reactive Silica in a Cementitious System: A Comparative Study

Directory of Open Access Journals (Sweden)

Weiting Xu

2016-03-01

Full Text Available This study comparably assessed the pozzolanic effect of silica fume (SF and ground rice husk ash (RHA as supplementary cementing materials on the properties of blended cement pastes and concretes. A commonly commercial silica fume (SF and locally-produced rice husk ash (RHA samples with two finenesses (one with larger size than cement and the other with smaller size than cement were used in this study. Material properties of SF and RHA were experimentally characterized. Hydration and mechanical properties of cement pastes incorporating SF and RHA were determined by thermogravimetric analysis (TGA and compressive strength tests, respectively. Properties of concretes regarding workability, mechanical property, durability, and microstructure were evaluated. Results showed that, although the finely ground RHA used in this study possessed lower SiO2 content and higher particle size compared to SF, it exhibited comparable pozzolanic reactivity with SF due to the nano-scale pores on its each single particle, leading to a higher specific surface area. The optimal replacement levels of SF and RHA were 10% by weight of cement in pastes and concretes. Although addition of SF and RHA led to a significant reduction in slump for the fresh mixtures, inclusion of up to 30% of SF or 15% of ground RHA did not adversely affect the strength of concretes. At the same mix, incorporation of finely-ground RHA in cement composites provided comparable mechanical properties, hydration degree, and durability with SF blended cement composites, owing to the porous structure and high specific surface area of RHA particles. Microstructure morphology analysis of concretes explored by scanning electron microscopy (SEM further validated the strength and the durability test results.

Experimental studies of Micro- and Nano-grained UO₂: Grain Growth Behavior, Sufrace Morphology, and Fracture Toughness

Energy Technology Data Exchange (ETDEWEB)

Miao, Yinbin [Argonne National Lab. (ANL), Argonne, IL (United States); Mo, Kun [Argonne National Lab. (ANL), Argonne, IL (United States); Jamison, Laura M. [Argonne National Lab. (ANL), Argonne, IL (United States); Lian, Jie [Rensselaer Polytechnic Inst., Troy, NY (United States); Yao, Tiankai [Rensselaer Polytechnic Inst., Troy, NY (United States); Bhattacharya, Sumit [Argonne National Lab. (ANL), Argonne, IL (United States); Northwestern Univ., Evanston, IL (United States)

2016-01-01

This activity is supported by the US Nuclear Energy Advanced Modeling and Simulation (NEAMS) Fuels Product Line (FPL) and aims at providing experimental data for the validation of the mesoscale simulation code MARMOT. MARMOT is a mesoscale multiphysics code that predicts the coevolution of microstructure and properties within reactor fuel during its lifetime in the reactor. It is an important component of the Moose-Bison-Marmot (MBM) code suite that has been developed by Idaho National Laboratory (INL) to enable next generation fuel performance modeling capability as part of the NEAMS Program FPL. In order to ensure the accuracy of the microstructure-based materials models being developed within the MARMOT code, extensive validation efforts must be carried out. In this report, we summarize the experimental efforts in FY16 including the following important experiments: (1) in-situ grain growth measurement of nano-grained UO₂; (2) investigation of surface morphology in micrograined UO₂; (3) Nano-indentation experiments on nano- and micro-grained UO₂. The highlight of this year is: we have successfully demonstrated our capability to in-situ measure grain size development while maintaining the stoichiometry of nano-grained UO₂ materials; the experiment is, for the first time, using synchrotron X-ray diffraction to in-situ measure grain growth behavior of UO₂.

Study of the morphology exhibited by exfoliated polyurethane/montmorillonite nano composites during in situ recovery tests

Energy Technology Data Exchange (ETDEWEB)

Pereira, Iaci M., E-mail: iaci@ctex.eb.br [Divisao Belica do Centro Tecnologico do Exercito. CTEx, Rio de Janeiro, RJ (Brazil); Orefice, Rodrigo L. [Universidade Federal de Minas Gerais Departamento de Metalurgia e Materiais. UFMG, Belo Horizonte, MG (Brazil)

2011-07-01

By using small-angle X-ray scattering, this study aims to examine the SM behavior of montmorillonite polyurethane nano composites. To investigate the phase morphology, a deformed specimen was placed on a heating stage mounted at the Synchrotron beamline; the shape recovery was measured during 15 min. As temperature increases, the crystalline fraction rapidly decreases. The degree of clay delamination within the matrix increases, disturbing the formation of hard and soft segments. Deformation induces changes in the phase proportion, increasing the disperse phase contribution. During in situ tests, the ratio between matrix and disperse phase reaches an equilibrium controlled by the temperature. (author)

Synthesis and characterization of nano structures of Silica SBA-16 containing Gadolinium-159 as potential nanoparticulated system for cancer therapy; Sintese e caracterizacao de nanoestruturas de Silica SBA-16 contendo Gadolinio-159 como potencial sistema nanoparticulado para o tratamento do cancer

Energy Technology Data Exchange (ETDEWEB)

Oliveira, Andre Felipe de

2013-07-01

Cancer is a leading cause of death worldwide, and malignant neoplasms of the lung, stomach, liver, colon and breast in greater numbers. And recently observed in the literature a large number of reviews where new materials, especially nanoparticle, has been studied as drug carriers and radioisotopes applied to cancer treatment. How mesoporous materials based on silica, thanks to its huge surface area and biocompatibility, have been studied intensively providing broad applications in various areas, the use of nanostructured silica SBA-16 might be a carrier specific radioisotope accumulate in the cells malignant. Thus the aim of this study is to develop in vitro studies using SBA-16 can selectively concentrate in malignant cells therapeutic amounts of the radioisotope Gadolinium-159 escorting them to death. This work was performed orderly synthesis of mesoporous silica, SBA-16 and incorporating the complex Gd-DTPA-BMA, as well as chemical and structural characterization. The techniques used to analyze the occurrence of the incorporation of the gadolinium complex in the silica matrix were elemental analysis (CHN), atomic emission spectroscopy (ICP-AES), infrared spectroscopy (FTIR), nitrogen adsorption (BET), small-angle X-ray scattering (SAXS) and thermogravimetric analysis (TG). To analyze the morphology of pure silica used the scanning electron microscopy (SEM) and transmission electron microscopy (TEM). By photon correlation spectroscopy (PCS) it was possible to obtain a measure of mean particle size, the polydispersity index (PDI) of the silica SBA-16, and the zeta potential by laser Doppler anemometry (LDA). The results of incorporation analyzed by ICP-AES indicated that the material SBA-16 had a higher rate of incorporation of gadolinium (93%). The release kinetics in simulated body fluid, showed considerable stability and low release (1%). The mesoporous silica SBA-16 showed cell viability in direct contact with cell culture. Samples with gadolinium

Controlling morphology and crystallite size of Cu(In{sub 0.7}Ga{sub 0.3})Se{sub 2} nano-crystals synthesized using a heating-up method

Energy Technology Data Exchange (ETDEWEB)

Hsu, Wei-Hsiang [Department of Resources Engineering, Particulate Materials Research Center, National Cheng Kung University, Tainan, 70101 Taiwan (China); Hsiang, Hsing-I, E-mail: hsingi@mail.ncku.edu.tw [Department of Resources Engineering, Particulate Materials Research Center, National Cheng Kung University, Tainan, 70101 Taiwan (China); Chia, Chih-Ta [Department of Physics, National Taiwan Normal University, Taipei, 116 Taiwan (China); Yen, Fu-Su [Department of Resources Engineering, Particulate Materials Research Center, National Cheng Kung University, Tainan, 70101 Taiwan (China)

2013-12-15

CuIn{sub 0.7}Ga{sub 0.3}Se{sub 2}(CIGS) nano-crystals were successfully synthesized via a heating-up process. The non-coordinating solvent (1-octadecene) and selenium/cations ratio effects on the crystalline phase and crystallite size of CIGS nano-crystallites were investigated. It was observed that the CIGS nano-crystallite morphology changed from sheet into spherical shape as the amount of 1-octadecene addition was increased. CIGS nano-crystals were obtained in 9–20 nm sizes as the selenium/cations ratio increased. These results suggest that the monomer reactivity in the solution can be adjusted by changing the solvent type and selenium/cations ratio, hence affecting the crystallite size and distribution. - Graphical abstract: CuIn{sub 0.7}Ga{sub 0.3}Se{sub 2}(CIGS) nano-crystals were successfully synthesized via a heating-up process in this study. The super-saturation in the solution can be adjusted by changing the OLA/ODE ratio and selenium/cation ratio.

Synthesis of Vertically Aligned ZnO Nano rods on Various Substrates

International Nuclear Information System (INIS)

Hassan, J.J.; Hassan, Z.; Abu Hassan, H.; Mahdi, M.A.

2011-01-01

We successfully synthesized vertically aligned ZnO nano rods on Si, GaN, Sic, Al 2 O 3 , ITO, and quartz substrates using microwave assisted chemical bath deposition (MA-CBD) method. All these types of substrates were seeded with PVA-ZnO nano composites layer prior to the nano rods growth. The effect of substrate type on the morphology of the ZnO nano rods was studied. The diameter of grown ZnO nano rods ranged from 50 nm to 200 nm. Structural quality and morphology of ZnO nano rods were determined by x-ray diffraction and scanning electron microscopy, which revealed hexagonal wurtzite structures perpendicular to the substrate along the z-axis in the direction of (002). Photoluminescence measurements of grown ZnO nano rods on all substrates exhibited high UV peak intensity. Raman scattering studies were conducted to estimate the lattice vibration modes. (author)

An investigation on morphology and mechanical properties of HDPE/nanoclay/nanoCaCO{sub 3} ternary nanocomposites

Energy Technology Data Exchange (ETDEWEB)

Garmabi, Hamid, E-mail: garmabi@aut.ac.ir; Tabari, Seyed Emad Alavi; Javadi, Azizeh [Department of Polymer Engineering and Color Technology, Amirkabir University of Technology - Tehran - Iran (Iran, Islamic Republic of); Behrouzi, Hormoz; Hosseini, Gholamabbas [Boushehr Province Gas Company - Boushehr - Iran (Iran, Islamic Republic of)

2016-03-09

Ternary Nanocomposites of high-density polyethylene (HDPE) containing two types of nano particles, a layered organoclay (Closite 15A) and a spherical nano Calcium Carbonate (CaCO{sub 3}), with various compositions were prepared using melt mixing. Maleic anhydride grafted polyethylene (MA-g-PE) was used to enhance the dispersion of nanofillers and better interface adhesion. Three different levels of nanoclay (1, 3, 5 wt. %), CaCO{sub 3} (6, 8, 10 wt. %) and MA-g-PE (3, 6, 9 wt. %) were used. The mixing was done in two steps: First a concentrated masterbatch of nanoparticles in HPDE and MA-g-PE was prepared using an internal mixer and then melt-mixing of nanocomposites was done in a lab scale co-rotating twin screw extruder. The morphology of samples was studied using Scanning Electron Microscopy (SEM) and mechanical properties were evaluated using tensile and impact tests. According to the SEM micrographs, nanofillers were well dispersed in the HDPE matrix and XRD patterns showed the intercalation of nanoclay layers too. Generally using the layered nanoclay can enhance the tensile modulus while the use of spherical nano CaCO{sub 3} results into improved toughness. It was found that co-incorporation of these two types of nanofillers, leads to improve the stiffness and minimize the reduction of impact strength, simultaneously.

Polyaniline nanowires on TiO2 nano/microfiber hierarchical nano/microstructures: Preparation and their photocatalytic properties

International Nuclear Information System (INIS)

Yu Qiaozhen; Wang Mang; Chen Hongzheng; Dai Zhengwei

2011-01-01

Highlights: → We fabricate PANI nanowire-on-TiO 2 nano/microfiber hierarchical nano/microstructure composite fiber films by electrospinning, calcinations and in situ polymerization. → PANI/TiO 2 composite fiber film exhibits high photocatalytic activity for the degradation of dye MB. → The photocatalytic activity and reusability of PANI/TiO 2 composite fiber film were lower than those of pure TiO 2 fiber film. - Abstract: TiO 2 /PANI composite fiber films were fabricated by electrospinning, calcinations and in situ polymerization. The morphology and structure of the resulting composites were analyzed by scanning electron micrograph, transmission electron micrograph, Fourier transform infrared spectroscopy and X-ray diffraction. It was found that this composite fiber film has a PANI nanowire-on-TiO 2 nano/microfiber hierarchical nano/microstructure. The surface morphology of this hierarchical nano/microstructure was related to the structure of TiO 2 nano/microfiber film, the time and temperature of in situ polymerization. Its photocatalytic property on methylene blue (MB) was studied, and the results showed that TiO 2 /PANI composite fiber film with this hierarchical nano/microstructure exhibited high photocatalytic activity for the degradation of MB under natural light. But both its photocatalytic activity and reusability were lower than those of pure TiO 2 fiber film. To improve the stability and reusability of TiO 2 /PANI composite fiber film, a direct chemical bonding of PANI chains onto TiO 2 surface, such as, the surface-initiated graft polymerization, is a useful method.

Dynamic studies of nano-confined polymer thin films

Science.gov (United States)

Geng, Kun

Polymer thin films with the film thickness (h0 ) below 100 nm often exhibit physical properties different from the bulk counterparts. In order to make the best use of polymer thin films in applications, it is important to understand the physical origins of these deviations. In this dissertation, I will investigate how different factors influence dynamic properties of polymer thin films upon nano-confinement, including glass transition temperature (Tg), effective viscosity (etaeff) and self-diffusion coefficient (D ). The first part of this dissertation concerns the impacts of the molecular weight (MW) and tacticity on the Tg's of nano-confined polymer films. Previous experiments showed that the Tg of polymer films could be depressed or increased as h0 decreases. While these observations are usually attributed to the effects of the interfaces, some experiments suggested that MW's and tacticities might also play a role. To understand the effects of these factors, the Tg's of silica-based poly(alpha-methyl styrene) (PalphaMS/SiOx) and poly(methyl methacrylate) (PMMA/SiOx) thin films were studied, and the results suggested that MW's and tacticities influence Tg in nontrivial ways. The second part concerns an effort to resolve the long-standing controversy about the correlation between different dynamics of polymer thin films upon nano-confinement. Firstly, I discuss the experimental results of Tg, D and etaeff of poly(isobutyl methacrylate) films supported by silica (PiBMA/SiOx). Both T g and D were found to be independent of h 0, but etaeff decreased with decreasing h 0. Since both D and etaeff describe transport phenomena known to depend on the local friction coefficient or equivalently the local viscosity, it is questionable why D and etaeff displayed seemingly inconsistent h 0 dependencies. We envisage the different h0 dependencies to be caused by Tg, D and etaeff being different functions of the local T g's (Tg,i) or viscosities (eta i). By assuming a three

Morphology, defect evolutions and nano-mechanical anisotropy of behenic acid monolayer

International Nuclear Information System (INIS)

Yang Guanghong; Jiang Xiaohong; Dai Shuxi; Cheng Gang; Zhang Xingtang; Du Zuliang

2010-01-01

Langmuir-Blodgett monolayers of behenic acid (BA) were prepared by the vertical deposition method and their morphological evolutions and nano-mechanical anisotropy were studied by atomic force microscopy (AFM) and lateral force microscopy. Results show that there are platforms in the differential surface pressure-area (π-A) isotherm presenting linear relations between the chain tilting angles and surface pressures. The reorganization, appearance and disappearance of defects such as pinholes and holes can strongly affect the profile of π-A isotherm; AFM images reflect evolution rules from pinholes to holes, and from monolayer to bilayers along with compression and relaxation of structures in BA monolayer. Due to higher molecule density and larger real contact area, the tip-monolayer contacts at 15 and 25 mN/m correspond to the Derjaguin-Muller-Toporov (DMT) model showing long-ranged interaction forces. But owing to more easily-deformed conformations, contacts at 5 and 35 mN/m accord with the Johnson-Kendall-Robert and DMT transition cases exhibiting short-ranged interface interactions. A little higher friction is proved in the direction perpendicular to the deposition.

Effect of Different Nano-Sized Silica Sols as Supports on the Structure and Properties of Cu/SiO2 for Hydrogenation of Dimethyl Oxalate

Directory of Open Access Journals (Sweden)

Chuancai Zhang

2017-02-01

Full Text Available Cu/x-SiO2 catalysts with 4, 10, and 20 nm silica sols as supports was produced by ammonia evaporation method and characterized. Different nano-sized silica sols as supports significantly affected the structure and catalytic properties of the copper catalysts for ethylene glycol synthesis from dimethyl oxalate. Compared with Cu/20-SiO2 and Cu/4-SiO2 catalysts, the catalytic performance and stability of Cu/10-SiO2 catalyst were greatly enhanced. The Cu/10-SiO2 catalyst showed 99.9% conversion with 94% EG selectivity and a lifetime of over 3080 h if it is calculated by industrial weight liquid hourly space velocity (WLHSV of 0.5 h−1. The Cu/10-SiO2 catalyst has one of the longest lifetimes among the catalysts and is a good alternative catalyst for this reaction. Improvement in the catalytic performance and stability of Cu/10-SiO2 is attributed to the proper SBET, Dp and larger dispersion of copper. In addition, the supports of Cu/10-SiO2 catalyst have smaller particles than that of Cu/20-SiO2; thus, the migration and growth of copper species in catalysts are restrained during the reaction.

Editorial Emerging Multifunctional Nano structures

International Nuclear Information System (INIS)

Fan, H.; Lu, Y.; Ramanath, G.; Pomposo, J.A.

2009-01-01

The interest in emerging nano structures is growing exponentially since they are promising building blocks for advanced multifunctional nano composites. In recent years, an evolution from the controlled synthesis of individual monodisperse nanoparticles to the tailored preparation of hybrid spherical and also unsymmetrical multiparticle nano structures is clearly observed. As a matter of fact, the field of nano structures built around a nano species such as inside, outside, and next to a nanoparticle is becoming a new evolving area of research and development with potential applications in improved drug delivery systems, innovative magnetic devices, biosensors, and highly efficient catalysts, among several others Emerging nano structures with improved magnetic, conducting and smart characteristics are currently based on the design, synthesis, characterization and modeling of multifunctional nano object-based materials. In fact, core-shell nanoparticles and other related complex nano architectures covering a broad spectrum of materials (from metal and metal oxide to fused carbon, synthetic polymer, and bio polymer structures) to nano structure morphologies (spherical, cylindrical, star-like, etc.) are becoming the main building blocks for next generation of drug delivery systems, advanced sensors and biosensors, or improved nano composites. The five papers presented in this special issue examine the preparation and characterization of emerging multifunctional materials, covering from hybrid asymmetric structures to engineering nano composites.

Higher order mode excitation in eccentric active nano-particles for tailoring of the near-field radiation

DEFF Research Database (Denmark)

Thorsen, R. O.; Arslanagic, Samel

2015-01-01

We examine the excitation of resonant modes inside eccentrically layered cylindrical active nano-particles. The nano-particle is a three-layer structure comprised of a silica core, a free-space middle layer, and an outer shell of silver. It is shown that a concentric configuration, initially desi...... of the gain constant, is shown to be controlled by the direction of the core displacement. The present eccentric active nano-particles may provide alternative strategies for directive near-field radiation relative to the existing designs....

Eu3+/Tb3+-doped La2O2CO3/La2O3 nano/microcrystals with multiform morphologies: facile synthesis, growth mechanism, and luminescence properties.

Science.gov (United States)

Li, Guogang; Peng, Chong; Zhang, Cuimiao; Xu, Zhenhe; Shang, Mengmeng; Yang, Dongmei; Kang, Xiaojiao; Wang, Wenxin; Li, Chunxia; Cheng, Ziyong; Lin, Jun

2010-11-15

LaCO(3)OH nano/microcrystals with a variety of morphologies/sizes including nanoflakes, microflowers, nano/microrhombuses, two-double microhexagrams sandwichlike microspindles, and peach-nucleus-shaped microcrystals have been synthesized via a facile homogeneous precipitation route under mild conditions. A series of controlled experiments indicate that the pH values in the initial reaction systems, carbon sources, and simple ions (NH(4)(+) and Na(+)) were responsible for the shape determination of the LaCO(3)OH products. A possible formation mechanism for these products with diverse architectures has been presented. After annealing at suitable temperatures, LaCO(3)OH was easily converted to La(2)O(2)CO(3) and La(2)O(3) with the initial morphologies. A systematic study on the photoluminescence and cathodoluminescence properties of Eu(3+)- or Tb(3+)-doped La(2)O(2)CO(3)/La(2)O(3) samples has been performed in detail. The excitation and site-selective emission spectra were recorded to investigate the microstructure, site symmetry, and difference in the (5)D(0) → (7)F(2) transition of Eu(3+) ions in La(2)O(2)CO(3) and La(2)O(3) host lattices. In addition, the dependence of the luminescent intensity on the morphology for the as-prepared La(2)O(2)CO(3)/La(2)O(3):Ln(3+) (Ln = Eu, Tb) samples has been investigated. The ability of generating diverse morphologies and multiemitting colors for different rare-earth activator ion (Ln = Eu, Tb) doped La(2)O(2)CO(3)/La(2)O(3) nano/microstructures provides a great opportunity for the systematic evaluation of morphology-dependent luminescence properties, as well as the full exploration of their application in many types of color display fields.

Characterizing the Nano and Micro Structure of Concrete toImprove its Durability

Energy Technology Data Exchange (ETDEWEB)

Monteiro, P.J.M.; Kirchheim, A.P.; Chae, S.; Fischer, Peter; MacDowell, Alastair; Schaible, Eirc; Wenk, H.R.; Macdowell, Alastair A.

2009-01-13

New and advanced methodologies have been developed to characterize the nano and microstructure of cement paste and concrete exposed to aggressive environments. High resolution full-field soft X-ray imaging in the water window is providing new insight on the nano scale of the cement hydration process, which leads to a nano-optimization of cement-based systems. Hard X-ray microtomography images of ice inside cement paste and cracking caused by the alkali?silica reaction (ASR) enables three-dimensional structural identification. The potential of neutron diffraction to determine reactive aggregates by measuring their residual strains and preferred orientation is studied. Results of experiments using these tools are shown on this paper.

Synthesis of Various Silica Nanoparticles for Foam Stability

International Nuclear Information System (INIS)

Yoon, Suk Bon; Yoon, Inho; Jung, Chonghun; Kim, Chorong; Choi, Wangkyu; Moon, Jeikwon

2013-01-01

The synthesis of the non-porous silica nanoparticles with uniform sizes has been reported through the Sto ber method, the synthesis of meso porous silica nanoparticles with a specific morphology such as core-shell, rod-like, and hexagonal shapes is not so common. As a synthetic strategy for controlling the particle size, shape, and porosity, the synthesis of core-shell silicas with meso porous shells formed on silica particle cores through the self-assembly of silica precursor and organic templates or spherical meso porous silicas using modified Sto ber method was also reported. Recently, in an effort to reduce the amount of radioactive waste and enhance the decontamination efficiency during the decontamination process of nuclear facilities contaminated with radionuclides, a few research for the preparation of the decontamination foam containing solid nanoparticles has been reported. In this work, the silica nanoparticles with various sizes, shapes, and structures were synthesized based on the previous literatures. The resulting silica nanoparticles were used to investigate the effect of the nanoparticles on the foam stability. In a study on the foam stability using various silica nanoparticles, the results showed that the foam volume and liquid volume in foam was enhanced when using a smaller size and lower density of the silica nanoparticles. Silica nanoparticles with various sizes, shapes, and structures such as a non-porous, meso porous core-shell, and meso porous silica were synthesized to investigate the effect of the foam stability. The sizes and structural properties of the silica nanoparticles were easily controlled by varying the amount of silica precursor, surfactant, and ammonia solution as a basic catalyst. The foam prepared using various silica nanoparticles showed that foam the volume and liquid volume in the foam were enhanced when using a smaller size and lower density of the silica nanoparticles

Controlling the synthesis conditions for silica nanosphere from semi-burned rice straw

International Nuclear Information System (INIS)

Hessien, M.M.; Rashad, M.M.; Zaky, R.R.; Abdel-Aal, E.A.; El-Barawy, K.A.

2009-01-01

Silica nanoparticles have been prepared through dissolution-precipitation process from rice straw ash (RSA) for different electronic applications. The dissolution of silica from RSA was carried out using alkali leaching process by sodium hydroxide. The precipitation of silica from the produced sodium silicate solution was carried out using sulphuric acid at pH 7. The factors affecting the precipitation process of the sodium silicate solution of dissociated RSA; such as; sodium silicate concentration, sulfuric acid concentration and addition of anionic surfactant (sodium dodecyl sulfate, SDS) on the particle size of the precipitated silica were studied. X-ray diffraction (XRD), X-ray fluorescence (XRF), specific surface area S BET and transmission electron microscope (TEM) have been used for the characterization of the produced nano-silica. The results showed that the optimum conditions of the dissolution efficiency of the silica of about 99% was achieved at 100 deg. C for 4 h, and NaOH/SiO 2 molar ratio three. The particle size of the precipitated silica gel was decreased with increasing Na 2 SiO 3 and SDS concentrations, while H 2 SO 4 concentration had insignificant effect. Particle size of about 16 nm can be achieved at 30% Na 2 SiO 3 , 4% H 2 SO 4 and 200 ppm SDS. The produced silica had 99.93% purity, amorphous and nanosphere particles with narrow size distribution. The produced silica can be used in many applications especially for chemical mechanical polishing (CMP) slurries for semiconductors industries.

Combined effect of nano-SiO2 and nano-Fe2O3 on compressive strength, flexural strength, porosity and electrical resistivity in cement mortars; Influencia de la combinación de nano-SiO2 y nano-Fe2O3 en la resistencia a compresión, resistencia a tracción, porosidad y resistividad eléctrica de morteros de cemento.

Energy Technology Data Exchange (ETDEWEB)

Sanjuán, M.A.; Argiz, C.; Gálvez, J.C.; Reyes, E.

2018-04-01

The compressive strength, flexural strength, porosity and electrical resistivity properties of cement mortars with nano-Fe2O3 and nano-SiO2 are studied. Amorphous silica is the main component of pozzolanic materials due to its reaction with calcium hydroxide formed from calcium silicate (C3S and C2S) hydration. The pozzolanic reaction rate is not only proportional to the amount of amorphous silica but also to the surface area available for reaction. Subsequently, fine nano-Fe2O3 and nano-SiO2 particles in mortars are expected to improve mortar performance. The experimental results showed that the compressive strength of mortars with nano-Fe2O3 and nano-SiO2 particles were lower than those obtained with the reference mortar at seven and 28 days. It was shown that the nano-particles were not able to enhance mechanical strength on every occasion. The continuous microstructural progress monitored by mercury intrusion porosimetry (MIP) measurements, pore-size distribution (PSD), total porosity and critical pore diameter also confirmed such results. [Spanish] Se estudia la resistencia a compresión y flexión, porosidad y resistividad eléctrica de morteros de cemento con nano-Fe2O3 y nano-SiO2. La sílice amorfa reacciona con el hidróxido de calcio formado en la hidratación del C3S y C2S. La tasa de reacción puzolánica es proporcional a la cantidad de sílice amorfa y la superficie disponible para la reacción, esperando que las partículas finas de nano-Fe2O3 y nano-SiO2 mejoren las propiedades de los morteros. Los resultados experimentales han mostrado que la resistencia a compresión a siete y 28 días de morteros con partículas de nano-Fe2O3 y nano-SiO2 era, en ocasiones, inferior a la obtenida con el mortero de referencia. Se muestra que las nano-partículas no siempre son capaces de mejorar la resistencia de los morteros. Las medidas mediante porosimetría de intrusión de mercurio (PIM) de la distribución de tamaño de poro (DTP), porosidad total y di

Refractive index engineering in silica glass

DEFF Research Database (Denmark)

Kristensen, Martin

2003-01-01

. This way the glass undergoes significant physical and chemical changes and in some cases very large non-linear effects have been demonstrated. This includes a non-linear coefficient around 22 pm/V in a wavelength range near 800 nm. The author believes this is due to the combined action of silver nano......The thesis covers research performed durint the last eight years by the author in collaboration with members of his group within the field of UV-written gratings and poling of silica-based materials. The subjects cover several steps on the value chain from basic physics and chemistry via component...... in detail in chapters 4,5 and 6. Chapter 4 describes the semi-classsical model developed by the author to describe the basic UV-induced processes in germanium-doped silica. The idea behind the model is that oxygen-deficient germanium centres in the glass work as gates for the UV-photon energy, which...

Formation of Uniform Hollow Silica microcapsules

Science.gov (United States)

Yan, Huan; Kim, Chanjoong

2013-03-01

Microcapsules are small containers with diameters in the range of 0.1 - 100 μm. Mesoporous microcapsules with hollow morphologies possess unique properties such as low-density and high encapsulation capacity, while allowing controlled release by permeating substances with a specific size and chemistry. Our process is a one-step fabrication of monodisperse hollow silica capsules with a hierarchical pore structure and high size uniformity using double emulsion templates obtained by the glass-capillary microfluidic technique to encapsulate various active ingredients. These hollow silica microcapsules can be used as biomedical applications such as drug delivery and controlled release.

Phosphorylated nano-diamond/ Polyimide Nanocomposites

International Nuclear Information System (INIS)

Beyler-Çiǧil, Asli; Çakmakçi, Emrah; Kahraman, Memet Vezir

2014-01-01

In this study, a novel route to synthesize polyimide (PI)/phosphorylated nanodiamond films with improved thermal and mechanical properties was developed. Surface phosphorylation of nano-diamond was performed in dichloromethane. Phosphorylation dramatically enhanced the thermal stability of nano-diamond. Poly(amic acid) (PAA), which is the precursor of PI, was successfully synthesized with 3,3',4,4'-Benzophenonetetracarboxylic dianhydride (BTDA) and 4,4'-oxydianiline (4,4'-ODA) in the solution of N,N- dimethylformamide (DMF). Pure BTDA-ODA polyimide films and phosphorylated nanodiamond containing BTDA-ODA PI films were prepared. The PAA displayed good compatibility with phosphorylated nano-diamond. The morphology of the polyimide (PI)/phosphorylated nano-diamond was characterized by scanning electron microscopy (SEM). Chemical structure of polyimide and polyimide (PI)/phosphorylated nano-diamond was characterized by FTIR. SEM and FTIR results showed that the phosphorylated nano-diamond was successfully prepared. Thermal properties of the polyimide (PI)/phosphorylated nanodiamond was characterized by thermogravimetric analysis (TGA). TGA results showed that the thermal stability of (PI)/phosphorylated nano-diamond film was increased

Application of functionalized nano HMS type mesoporous silica with N-(2-aminoethyl-3-aminopropyl methyldimethoxysilane as a suitable adsorbent for removal of Pb (II from aqueous media and industrial wastewater

Directory of Open Access Journals (Sweden)

Hamedreza Javadian

2017-01-01

Full Text Available In this work, adsorption characteristics of nano NH2-HMS (functionalized HMS type mesoporous silica with amine groups for the removal of Pb (II ions from aqueous solutions were investigated. The adsorbent was characterized using FE-SEM, TEM, XRD, FTIR and BET. The adsorption of Pb (II ions by batch method was applied and the optimum conditions were investigated. In optimum experimental conditions, removal efficiency was 99.08%. It was found that temperature has a positive effect on the removal efficiency. The thermodynamic parameters were evaluated, as well. The evaluated thermodynamic parameters (ΔG, ΔH and ΔS showed that the adsorption of Pb (II ions onto nano NH2-HMS was feasible, spontaneous and endothermic in nature. It can be concluded that NH2-HMS is potentially able to remove Pb (II ions from aqueous solutions. Also, more than 90% of desorption efficiency was achieved using 0.01 M HNO3.

Morphology and stress at silicon-glass interface in anodic bonding

Energy Technology Data Exchange (ETDEWEB)

Tang, Jiali [Key Laboratory of Pressure Systems and Safety (MOE), School of Mechanical Engineering, East China University of Science and Technology, Shanghai 200237 (China); Cai, Cheng [State Key Laboratory of Chemical Engineering, East China University of Science and Technology, Shanghai (China); Ming, Xiaoxiang [Key Laboratory of Pressure Systems and Safety (MOE), School of Mechanical Engineering, East China University of Science and Technology, Shanghai 200237 (China); State Key Laboratory of Bioreactor Engineering, East China University of Science and Technology, Shanghai 200237 (China); State Key Laboratory of Chemical Engineering, East China University of Science and Technology, Shanghai (China); Yu, Xinhai, E-mail: yxhh@ecust.edu.cn [Key Laboratory of Pressure Systems and Safety (MOE), School of Mechanical Engineering, East China University of Science and Technology, Shanghai 200237 (China); State Key Laboratory of Bioreactor Engineering, East China University of Science and Technology, Shanghai 200237 (China); Zhao, Shuangliang, E-mail: szhao@ecust.edu.cn [State Key Laboratory of Chemical Engineering, East China University of Science and Technology, Shanghai (China); Tu, Shan-Tung [Key Laboratory of Pressure Systems and Safety (MOE), School of Mechanical Engineering, East China University of Science and Technology, Shanghai 200237 (China); Liu, Honglai [State Key Laboratory of Chemical Engineering, East China University of Science and Technology, Shanghai (China)

2016-11-30

Highlights: • Amorphous SiO{sub 2} is the most probable silica morphology generated in anodic bonding. • Amorphous SiO{sub 2} thickness at the interface is at least 2 nm for 90 min anodic bonding. • Silicon oxidation rate at the interface is 0.022 nm min{sup −1} from 30 to 90 min. - Abstract: The morphologies and structural details of formed silica at the interface of silicon-glass anodic bonding determine the stress at the interface but they have been rarely clarified. In this study, a miniaturized anodic bonding device was developed and coupled with a Raman spectrometer. The silicon-glass anodic bonding was carried out and the evolution of the stress at the bonding interface was measured in situ by a Raman spectrometer. In addition, large-scale atomistic simulations were conducted by considering the formed silica with different morphologies. The most conceivable silica morphology was identified as the corresponding silicon-glass interfacial stress presents qualitatively agreement with the experimental observation. It was found that amorphous SiO{sub 2} is the silica morphology generated in anodic bonding. The amorphous SiO{sub 2} thickness is at least 2 nm in the case of 90 min anodic bonding at 400 °C with the DC voltage of −1000 V. The combination of experimental and simulation results can ascertain the silicon oxidation reaction rate in anodic bonding process, and under the above-mentioned condition, the reaction rate was estimated as 0.022 nm min{sup −1} from 30 to 90 min.

Sonochemical synthesis of silica particles and their size control

Energy Technology Data Exchange (ETDEWEB)

Kim, Hwa-Min [Advanced Materials and Chemical Engineering, Catholic University of Daegu, Gyeongbuk 38430 (Korea, Republic of); Lee, Chang-Hyun [Electronic and Electrical Engineering, Catholic University of Daegu, Gyeongbuk 38430 (Korea, Republic of); Kim, Bonghwan, E-mail: bhkim@cu.ac.kr [Electronic and Electrical Engineering, Catholic University of Daegu, Gyeongbuk 38430 (Korea, Republic of)

2016-09-01

Graphical abstract: - Highlights: • Silica particles were easily prepared by an ultrasound-assisted sol–gel method. • The particle size was controlled by the ammonium hydroxide/water molar ratio. • The size-controlled diameter of silica particles ranged from 40 to 400 nm. • The particles were formed in a relatively short reaction time. - Abstract: Using an ultrasound-assisted sol–gel method, we successfully synthesized very uniformly shaped, monodisperse, and size-controlled spherical silica particles from a mixture of ethanol, water, and tetraethyl orthosilicate in the presence of ammonia as catalyst, at room temperature. The diameters of the silica particles were distributed in the range from 40 to 400 nm; their morphology was well characterized by scanning electron microscopy. The silica particle size could be adjusted by choosing suitable concentrations of ammonium hydroxide and water, which in turn determined the nucleation and growth rates of the particles during the reaction. This sonochemical-based silica synthesis offers an alternative way to produce spherical silica particles in a relatively short reaction time. Thus, we suggest that this simple, low-cost, and efficient method of preparing uniform silica particles of various sizes will have practical and wide-ranging industrial applicability.

Preparation of Mesoporous Silica-Supported Palladium Catalysts for Biofuel Upgrade

Directory of Open Access Journals (Sweden)

Ling Fei

2012-01-01

Full Text Available We report the preparation of two hydrocracking catalysts Pd/CoMoO4/silica and Pd/CNTs/CoMoO4/silica (CNTs, carbon nanotubes. The structure, morphologies, composition, and thermal stability of catalysts were studied by X-ray diffraction (XRD, scanning electron microscopy (SEM, Raman spectroscopy, transmission electron microscopy (TEM, energy-dispersive X-ray (EDX, and thermogravimetric analysis (TGA. The catalyst activity was measured in a Parr reactor with camelina fatty acid methyl esters (FAMEs as the feed. The analysis shows that the palladium nanoparticles have been incorporated onto mesoporous silica in Pd/CoMoO4/silica or on the CNTs surface in Pd/CNTs/CoMoO4/silica catalysts. The different combinations of metals and supports have selective control cracking on heavy hydrocarbons.

Synchronized femtosecond laser pulse switching system based nano-patterning technology

Science.gov (United States)

Sohn, Ik-Bu; Choi, Hun-Kook; Yoo, Dongyoon; Noh, Young-Chul; Sung, Jae-Hee; Lee, Seong-Ku; Ahsan, Md. Shamim; Lee, Ho

2017-07-01

This paper demonstrates the design and development of a synchronized femtosecond laser pulse switching system and its applications in nano-patterning of transparent materials. Due to synchronization, we are able to control the location of each irradiated laser pulse in any kind of substrate. The control over the scanning speed and scanning step of the laser beam enables us to pattern periodic micro/nano-metric holes, voids, and/or lines in various materials. Using the synchronized laser system, we pattern synchronized nano-holes on the surface of and inside various transparent materials including fused silica glass and polymethyl methacrylate to replicate any image or pattern on the surface of or inside (transparent) materials. We also investigate the application areas of the proposed synchronized femtosecond laser pulse switching system in a diverse field of science and technology, especially in optical memory, color marking, and synchronized micro/nano-scale patterning of materials.

Nano sized bismuth oxy chloride by metal organic chemical vapour deposition

Energy Technology Data Exchange (ETDEWEB)

Jagdale, Pravin, E-mail: pravin.jagdale@polito.it [Department of Applied Science and Technology (DISAT), Politecnico di Torino, 10129 (Italy); Castellino, Micaela [Center for Space Human Robotics, Istituto Italiano di Tecnologia, Corso Trento 21, 10129 Torino (Italy); Marrec, Françoise [Laboratory of Condensed Matter Physics, University of Picardie Jules Verne (UPJV), Amiens 80039 (France); Rodil, Sandra E. [Instituto de Investigaciones en Materiales, Universidad Nacional Autonoma de Mexicom (UNAM), Mexico D.F. 04510 (Mexico); Tagliaferro, Alberto [Department of Applied Science and Technology (DISAT), Politecnico di Torino, 10129 (Italy)

2014-06-01

Metal organic chemical vapour deposition (MOCVD) method was used to prepare thin films of bismuth based nano particles starting from bismuth salts. Nano sized bismuth oxy chloride (BiOCl) crystals were synthesized from solution containing bismuth chloride (BiCl{sub 3}) in acetone (CH{sub 3}-CO-CH{sub 3}). Self-assembly of nano sized BiOCl crystals were observed on the surface of silicon, fused silica, copper, carbon nanotubes and aluminium substrates. Various synthesis parameters and their significant impact onto the formation of self-assembled nano-crystalline BiOCl were investigated. BiOCl nano particles were characterized by X-ray diffraction, X-ray photoelectron spectroscopy, field emission scanning electron microscopy, energy-dispersive X-ray spectroscopy and Micro-Raman spectroscopy. These analyses confirm that bismuth nanometer-sized crystal structures showing a single tetragonal phase were indeed bismuth oxy chloride (BiOCl) square platelets 18–250 nm thick and a few micrometres wide.

Preparation of thick silica coatings on carbon fibers with fine-structured silica nanotubes induced by a self-assembly process

Directory of Open Access Journals (Sweden)

Benjamin Baumgärtner

2017-05-01

Full Text Available A facile method to coat carbon fibers with a silica shell is presented in this work. By immobilizing linear polyamines on the carbon fiber surface, the high catalytic activity of polyamines in the sol–gel-processing of silica precursors is used to deposit a silica coating directly on the fiber’s surface. The surface localization of the catalyst is achieved either by attaching short-chain polyamines (e.g., tetraethylenepentamine via covalent bonds to the carbon fiber surface or by depositing long-chain polyamines (e.g., linear poly(ethylenimine on the carbon fiber by weak non-covalent bonding. The long-chain polyamine self-assembles onto the carbon fiber substrate in the form of nanoscopic crystallites, which serve as a template for the subsequent silica deposition. The silicification at close to neutral pH is spatially restricted to the localized polyamine and consequently to the fiber surface. In case of the linear poly(ethylenimine, silica shells of several micrometers in thickness can be obtained and their morphology is easily controlled by a considerable number of synthesis parameters. A unique feature is the hierarchical biomimetic structure of the silica coating which surrounds the embedded carbon fiber by fibrillar and interconnected silica fine-structures. The high surface area of the nanostructured composite fiber may be exploited for catalytic applications and adsorption purposes.

Structural, Morphological and Optical Characterization of Eu3+ and Nd3+ Co-Doped Tio2 Nano Particles by Sol Gel Method

Directory of Open Access Journals (Sweden)

P. Sanjay

2017-06-01

Full Text Available Semiconductor nano crystals have been widely studied for their fundamental properties. The Eu3+ and Nd3+ doped titanium dioxide nano powder was successfully synthesized by sol-gel method. The morphological and structural properties of as-prepared samples were characterized by X-ray diffraction (XRD, High Resolution Transmission Electron Microscope (HRTEM. The Powder X- ray diffraction is carried out in order to examine the phase formation and substitution of Eu3+ and Nd3+ doped in TiO2 matrix. The UV-Vis spectral analysis was carried out between 200 nm and 1200 nm. The band gap of the Eu3+ and Nd3+ doped Tio2 nanoparticles was calculated. The functional groups of the synthesized compound have been identified by FTIR spectral analysis. The strong PL intensity confirms a blue shift.

Gold micro- and nano-particles for surface enhanced vibrational spectroscopy of pyridostigmine bromide

DEFF Research Database (Denmark)

Dolgov, Leonid; Fesenko, Olena; Kavelin, Vladyslav

2017-01-01

Triangular gold microprisms and spherical silica nanoparticles with attached gold nano-islands were examined as an active nanostructures for the surface enhanced Raman and infrared spectroscopy. These particles were probed for the detection of pyridostigmine bromide as a safe analog of military c...

Characterizing the nano and micro structure of concrete to improve its durability

Energy Technology Data Exchange (ETDEWEB)

Monteiro, P.J.M.; Kirchheim, A.P.; Chae, S.; Fischer, P.; MacDowell, A.A.; Schaible, E.; Wenk, H.R.

2008-10-22

New and advanced methodologies have been developed to characterize the nano and microstructure of cement paste and concrete exposed to aggressive environments. High resolution full-field soft X-ray imaging in the water window is providing new insight on the nano scale of the cement hydration process, which leads to a nano-optimization of cement-based systems. Hard X-ray microtomography images on ice inside cement paste and cracking caused by the alkali-silica reaction (ASR) enables three-dimensional structural identification. The potential of neutron diffraction to determine reactive aggregates by measuring their residual strains and preferred orientation is studied. Results of experiments using these tools will be shown on this paper.

Characterizing the nano and micro structure of concrete to improve its durability

KAUST Repository

Monteiro, P.J.M.

2009-09-01

New and advanced methodologies have been developed to characterize the nano and microstructure of cement paste and concrete exposed to aggressive environments. High resolution full-field soft X-ray imaging in the water window is providing new insight on the nano scale of the cement hydration process, which leads to a nano-optimization of cement-based systems. Hard X-ray microtomography images of ice inside cement paste and cracking caused by the alkali-silica reaction (ASR) enables three-dimensional structural identification. The potential of neutron diffraction to determine reactive aggregates by measuring their residual strains and preferred orientation is studied. Results of experiments using these tools are shown on this paper. © 2009 Elsevier Ltd. All rights reserved.

Characterizing the nano and micro structure of concrete to improve its durability

KAUST Repository

Monteiro, P.J.M.; Kirchheim, A.P.; Chae, S.; Fischer, P.; MacDowell, A.A.; Schaible, E.; Wenk, H.R.

2009-01-01

New and advanced methodologies have been developed to characterize the nano and microstructure of cement paste and concrete exposed to aggressive environments. High resolution full-field soft X-ray imaging in the water window is providing new insight on the nano scale of the cement hydration process, which leads to a nano-optimization of cement-based systems. Hard X-ray microtomography images of ice inside cement paste and cracking caused by the alkali-silica reaction (ASR) enables three-dimensional structural identification. The potential of neutron diffraction to determine reactive aggregates by measuring their residual strains and preferred orientation is studied. Results of experiments using these tools are shown on this paper. © 2009 Elsevier Ltd. All rights reserved.

Ultrasonic-assisted synthesis of nano lead(II) coordination polymer as precursors for preparation of lead(II) oxide nano-structures: Thermal, optical properties and XRD studies.

Science.gov (United States)

Ghavidelaghdam, Elham; Shahverdizadeh, Gholam Hossein; Motameni Tabatabai, Javad; Mirtamizdoust, Babak

2018-04-01

Nano structure of a lead (II) coordination polymer [Pb 2 (C 2 Cl 3 O 2 ) 2 (NO 3 ) 2 (C l2 H 8 N 2 ) 2 ] n (1), has been synthesized by a sonochemical method in different concentrations. The nano particles were characterized by scanning electron microscopy (SEM) X-ray powder diffraction (XRD), FT-IR spectroscopy and elemental analyses. The thermal stability of nano structure is closely investigated via thermal gravimetric (TGA), and compared with crystalline structure. The compounds are then heated to 600 °C to produce PbO nano particles. The resulting PbO is characterized through XRD and SEM analyses. Concentration of initial reagents effects on size and morphology of nano-structured compound 1 have been studied and show that low concentrations of initial reagents decreased particles size and leaded to uniform nano particles morphology. The photoluminescence properties of the prepared compound, as crystalline and as nanoparticles, have been investigated. The result showed a good correlation between the size and emission wavelength. Copyright © 2017. Published by Elsevier B.V.

Preparation of silica nanoparticles through microwave-assisted acid-catalysis.

Science.gov (United States)

Lovingood, Derek D; Owens, Jeffrey R; Seeber, Michael; Kornev, Konstantin G; Luzinov, Igor

2013-12-16

Microwave-assisted synthetic techniques were used to quickly and reproducibly produce silica nanoparticle sols using an acid catalyst with nanoparticle diameters ranging from 30-250 nm by varying the reaction conditions. Through the selection of a microwave compatible solvent, silicic acid precursor, catalyst, and microwave irradiation time, these microwave-assisted methods were capable of overcoming the previously reported shortcomings associated with synthesis of silica nanoparticles using microwave reactors. The siloxane precursor was hydrolyzed using the acid catalyst, HCl. Acetone, a low-tan δ solvent, mediates the condensation reactions and has minimal interaction with the electromagnetic field. Condensation reactions begin when the silicic acid precursor couples with the microwave radiation, leading to silica nanoparticle sol formation. The silica nanoparticles were characterized by dynamic light scattering data and scanning electron microscopy, which show the materials' morphology and size to be dependent on the reaction conditions. Microwave-assisted reactions produce silica nanoparticles with roughened textured surfaces that are atypical for silica sols produced by Stöber's methods, which have smooth surfaces.

Structure and Properties of LENRA/ Silica Composite

International Nuclear Information System (INIS)

Mahathir Mohamed; Dahlan Mohd

2010-01-01

The sol-gel reaction using tetra ethoxysilane (TEOS) was conducted for modified natural rubber (NR) matrix to obtain in situ generated NR/ silica composite. The present of acrylate group in the modified NR chain turns the composite into radiation-curable. The maximum amount of silica generated in the matrix was 50 p hr by weight. During the sol-gel process the inorganic mineral was deposited in the rubber matrix forming hydrogen bonding between organic and inorganic phases. The composites obtained were characterized by various techniques including thermogravimetric analysis and infrared spectrometry to study their molecular structure. The increase in mechanical properties was observed for low silica contents ( 30 p hr) where more silica were generated, agglomerations were observed at the expense of the mechanical properties. From the DMTA data, it shows an increase of the interaction between the rubber and silica phases up to 30 p hr TEOS. Structure and morphology of the heterogeneous system were analyzed by transmission electron microscopy. The average particle sizes of between 150 nm to 300 nm were achieved for the composites that contain less than 20 p hr of TEOS. (author)

A novel synthesis of micrometer silica hollow sphere

International Nuclear Information System (INIS)

Pan Wen; Ye Junwei; Ning Guiling; Lin Yuan; Wang Jing

2009-01-01

Silica microcapsules (hollow spheres) were synthesized successfully by a novel CTAB-stabilized water/oil emulsion system mediated hydrothermal method. The addition of urea to a solution of aqueous phase was an essential step of the simple synthetic procedure of silica hollow spheres, which leads to the formation of silica hollow spheres with smooth shell during hydrothermal process. The intact hollow spheres were obtained by washing the as-synthesized solid products with distilled water to remove the organic components. A large amount of silanol groups were retained in the hollow spheres by this facile route without calcination. The morphologies and optical properties of the product were characterized by transmission electron microscopy, scanning electron microscopy (SEM) and Fourier transform infrared spectroscopy. Furthermore, on the basis of a series of SEM observations, phenomenological elucidation of a mechanism for the growth of the silica hollow spheres has been presented

Optical study of the ultrasonic formation process of noble metal nanoparticles dispersed inside the pores of monolithic mesoporous silica

CERN Document Server

Fu Gan Hua; Kan Cai Xia; Li Cun Cheng; Fang Qi

2003-01-01

Gold nanoparticles dispersed inside the pores of monolithic mesoporous silica were prepared by soaking the silica in a gold (III) ion solution and subsequent ultrasound irradiation. The formation process of gold nanoparticles in the pores of mesoporous silica was investigated based on optical measurements of wrapped and naked soaked silica after ultrasonic irradiation, and the reduction rate effect in solution and pre-soaking effect. It has been shown that acoustic cavitation cannot occur in nano-sized pores. The gold nanoparticles in silica are not formed in situ within the pores but produced mainly by diffusion of the gold clusters formed in the solution during irradiation into the pores. The radicals formed in solution are exhausted before entering the pores of silica. There exists a critical reduction rate in solution, at which the yield of gold nanoparticles in silica reaches a maximum, and above which there is a decrease in the yield. This is attributed to too quick a growth or aggregation of gold clust...

Nano ZnO embedded in Chitosan matrix for vibration sensor application

Science.gov (United States)

Praveen, E.; Murugan, S.; Jayakumar, K.

2015-06-01

Biopolymer Chitosan is embedded with various concentration of ZnO nano particle and such a bio-nano composite electret has been fabricated by casting method. The morphological, structural, optical and electrical characterization of the bio-nano composite electret film have been carried out. Isolation and piezoelectric measurements of bio-nano composite have also been carried out indicating the possibility of using it as a mechanical sensor element.

Supercritical Carbon Dioxide Assisted Processing of Silica/PMMA Nanocomposite Foams

Science.gov (United States)

Rende, Deniz; Schadler, Linda S.; Ozisik, Rahmi

2012-02-01

Polymer nanocomposite foams receive considerable attention in both scientific and industrial communities. These structures are defined as closed or open cells (pores) surrounded by bulk material and are widely observed in nature in the form of bone structure, sponge, corals and natural cork. Inspired by these materials, polymer nanocomposite foams are widely used in advanced applications, such as bone scaffolds, food packaging and transportation materials due to their lightweight and enhanced mechanical, thermal, and electrical properties compared to bulk polymer foams. The presence of the nanosized fillers facilitates heterogeneous bubble nucleation as a result, the number of bubbles increases while the average bubble size decreases. Therefore, the foam morphology can be controlled by the size, concentration, and surface chemistry of the nanofiller. In the current study, we used supercritical carbon dioxide as a foaming agent for silica/poly(methyl methacrylate), PMMA, foams. The silica nanoparticles were chemically modified by fluoroalkane chains to make them CO2-philic. The surface coverage was controlled via tethering density, and the effect of silica surface coverage and concentration on foam morphology was investigated through scanning electron microscopy and image processing. Results indicated that nanofiller concentration and filler surface chemistry (CO2-philicity) had tremendous effect on foam morphology but surface coverage did not have any effect.

Crystallization of biogenic hydrous amorphous silica

Science.gov (United States)

Kyono, A.; Yokooji, M.; Chiba, T.; Tamura, T.; Tuji, A.

2017-12-01

Diatom, Nitzschia cf. frustulum, collected from Lake Yogo, Siga prefecture, Japan was cultured in laboratory. Organic components of the diatom cell were removed by washing with acetone and sodium hypochlorite. The remaining frustules were studied by SEM-EDX, FTIR spectroscopy, and synchrotron X-ray diffraction. The results showed that the spindle-shaped morphology of diatom frustule was composed of hydrous amorphous silica. Pressure induced phase transformation of the diatom frustule was investigated by in situ Raman spectroscopic analysis. With exposure to 0.3 GPa at 100 oC, Raman band corresponding to quartz occurred at ν = 465 cm-1. In addition, Raman bands known as a characteristic Raman pattern of moganite was also observed at 501 cm-1. From the integral ratio of Raman bands, the moganite content in the probed area was estimated to be approximately 50 wt%. With the pressure and temperature effect, the initial morphology of diatom frustule was completely lost and totally changed to a characteristic spherical particle with a diameter of about 2 mm. With keeping the compression of 5.7 GPa at 100 oC, a Raman band assignable to coesite appeared at 538 cm-1. That is, with the compression and heating, the hydrous amorphous silica can be readily crystallized into quartz, moganite, and coesite. The first-principles calculations revealed that a disiloxane molecule stabilized in a trans configuration is twisted 60o and changed into the cis configuration with a close approach of water molecule. It is therefore a reasonable assumption that during crystallization of hydrous amorphous silica, the Si-O-Si bridging unit with the cis configuration would survive as a structural defect and then crystallized into moganite by keeping the geometry. This hypothesis is adaptable to the phase transformation from hydrous amorphous silica to coesite as well, because coesite has the four-membered rings and easily formed from the hydrous amorphous silica under high pressure and high

Polymer-filler interactions in polyether based thermoplastic polyureathane/silica nanocomposites

OpenAIRE

Heinz, Özge; Heinz, Ozge

2013-01-01

Thermoplastic polyurethaneureas (TPU) are a unique class of materials that are used in a broad range of applications due to their tailorable chemistry and morphology that allow engineering materials with targeted properties. The central theme of this dissertation is to develop an understanding on polymer-filler interfacial interactions and related reinforcing mechanism of silica nanoparticles in polyether based TPU/silica nanocomposites. Prior to our investigation on nanocomposite materials, ...

Preparation of novel film-forming armoured latexes using silica nanoparticles as a pickering emulsion stabiliser.

Science.gov (United States)

Shiraz, Hana; Peake, Simon J; Davey, Tim; Cameron, Neil R; Tabor, Rico F

2018-05-15

Film-forming polymer latex particles of diameter acrylate (BA) as co-monomers, potassium persulphate (KPS) as an initiator and a commercially available colloidal nano-silica (Ludox®-TM40). It was found that pH control before polymerisation using methacrylic acid (MAA) facilitated the formation of armoured latexes, and mechanistic features of this process are discussed. An alternative, more robust protocol was developed whereby addition of vinyltriethoxysilane (VTES) to control wettability resulted in latexes completely armoured in colloidal nano-silica. The latexes were characterised using SEM, cryo-TEM and AFM imaging techniques. The mechanism behind the adsorption was investigated through surface pressure and contact angle measurements to understand the factors that influence this irreversible adsorption. Results indicate that nanoparticle attachment (but intriguingly not latex size) is dependent on particle wettability, providing new insight into the formation of nanoparticle-armoured latexes, along with opportunities for further development of diversely functionalized inorganic/organic polymer composite particles. Copyright © 2018 Elsevier Inc. All rights reserved.

Presence of nano-sized silica during in vitro digestion of foods containing silica as a food additive

NARCIS (Netherlands)

Peters, R.; Kramer, E.; Oomen, A.G.; Herrera Rivera, Z.E.; Oegema, G.; Tromp, P.C.; Fokkink, R.; Rietveld, A.; Marvin, H.J.P.; Weigel, S.; Peijnenburg, A.A.C.M.; Bouwmeester, H.

2012-01-01

The presence, dissolution, agglomeration state, and release of materials in the nano-size range from food containing engineered nanoparticles during human digestion is a key question for the safety assessment of these materials. We used an in vitro model to mimic the human digestion. Food products

Nano zinc phosphate coatings for enhanced corrosion resistance of mild steel

International Nuclear Information System (INIS)

Tamilselvi, M.; Kamaraj, P.; Arthanareeswari, M.; Devikala, S.

2015-01-01

Highlights: • Nano zinc phosphate coating on mild steel was developed. • Nano zinc phosphate coatings on mild steel showed enhanced corrosion resistance. • The nano ZnO increases the number of nucleating sites for phosphating. • Faster attainment of steady state during nano zinc phosphating. - Abstract: Nano crystalline zinc phosphate coatings were developed on mild steel surface using nano zinc oxide particles. The chemical composition and morphology of the coatings were analyzed by X-ray diffraction analysis (XRD), scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDX). The particles size of the nano zinc phosphate coating developed was also characterized by TEM analysis. Potentiodynamic polarization and electrochemical impedance studies were carried out in 3.5% NaCl solution. Significant variations in the coating weight, morphology and corrosion resistance were observed as nano ZnO concentrations were varied from 0.25 to 2 g/L in the phosphating baths. The results showed that nano ZnO particles in the phosphating solution yielded phosphate coatings of higher coating weight, greater surface coverage and enhanced corrosion resistance than the normal zinc phosphate coatings (developed using normal ZnO particles in the phosphating baths). Better corrosion resistance was observed for coatings derived from phosphating bath containing 1.5 g/L nano ZnO. The activation effect brought about by the nano ZnO reduces the amount of accelerator (NaNO 2 ) required for phosphating

Hydrophilic nano-silica coating agents with platinum and diamond nanoparticles for denture base materials.

Science.gov (United States)

Yoshizaki, Taro; Akiba, Norihisa; Inokoshi, Masanao; Shimada, Masayuki; Minakuchi, Shunsuke

2017-05-31

Preventing microorganisms from adhering to the denture surface is important for ensuring the systemic health of elderly denture wearers. Silica coating agents provide high hydrophilicity but lack durability. This study investigated solutions to improve the durability of the coating layer, determine an appropriate solid content concentration of SiO 2 in the silica coating agent, and evaluate the effect of adding platinum (Pt) and diamond nanoparticles (ND) to the agent. Five coating agents were prepared with different SiO 2 concentrations with/without Pt and ND additives. The contact angle was measured, and the brush-wear test was performed. Scanning electron microscopy was used to investigate the silica coating layer. The appropriate concentration of SiO 2 was found to be 0.5-0.75 wt%. The coating agents with additives showed significantly high hydrophilicity immediately after coating and after the brush-wear test. The coating agents with/without additives formed a durable coating layer even after the brush-wear test.

Constrained Geometry Organotitanium Catalysts Supported on Nanosized Silica for Ethylene (co)Polymerization.

Science.gov (United States)

Li, Kuo-Tseng; Wu, Ling-Huey

2017-05-05

Supported olefin polymerization catalysts can prevent reactor-fouling problems and produce uniform polymer particles. Constrained geometry complexes (CGCs) have less sterically hindered active sites than bis-cyclopentadienyl metallocene catalysts. In the literature, micrometer-sized silica particles were used for supporting CGC catalysts, which might have strong mass transfer limitations. This study aims to improve the activity of supported CGC catalysts by using nanometer-sized silica. Ti[(C₅Me₄)SiMe₂(N t Bu)]Cl₂, a "constrained-geometry" titanium catalyst, was supported on MAO-treated silicas (nano-sized and micro-sized) by an impregnation method. Ethylene homo-polymerization and co-polymerization with 1-octene were carried out in a temperature range of 80-120 °C using toluene as the solvent. Catalysts prepared and polymers produced were characterized. For both catalysts and for both reactions, the maximum activities occurred at 100 °C, which is significantly higher than that (60 °C) reported before for supported bis-cyclopentadienyl metallocene catalysts containing zirconium, and is lower than that (≥140 °C) used for unsupported Ti[(C₅Me₄)SiMe₂(N t Bu)]Me₂ catalyst. Activities of nano-sized catalyst were 2.6 and 1.6 times those of micro-sized catalyst for homopolymerization and copolymerization, respectively. The former produced polymers with higher crystallinity and melting point than the latter. In addition, copolymer produced with nanosized catalyst contained more 1-octene than that produced with microsized catalyst.

Ultra-large bandwidth hollow-core guiding in all-silica bragg fibers with nano-supports

DEFF Research Database (Denmark)

Vienne, Guillaume; Xu, Yong; Jakobsen, Christian

2004-01-01

We demonstrate a new class of hollow-core Bragg fibers that are composed of concentric cylindrical silica rings separated by nanoscale support bridges. We theoretically predict and experimentally observe hollow-core confinement over an octave frequency range. The bandwidth of bandgap guiding in t...... in this new class of Bragg fibers exceeds that of other hollow-core fibers reported in the literature. With only three rings of silica cladding layers, these Bragg fibers achieve propagation loss of the order of 1 dB/m....

Synthesis of poly(ethylene oxide)-silica hybrids

International Nuclear Information System (INIS)

Ishak Manaf

2002-01-01

A hybrid material incorporating silica networks in poly (ethylene oxide) was produced using the sol-gel process from solution mixtures of poly (ethylene oxide) dissolved in water and partially polymerized tetraethylorthosilicate (TEOS) with and without compatibilisation agent. These mixtures were converted into films by solvent evaporation and drying them in an air-circulating oven at 60 degree C. Depending on the alkoxysilane solution composition and several mixing parameters, different morphologies were obtained, varying from semi-interpenetrating networks of PEO within highly cross linked silica chains, to finely dispersed heterogeneous system exhibiting either co-continuous or particulate microstructure. The influence of pH, type of solvents, mixing temperatures and time, as well as the nature of compatibiliser was found to be extremely important in controlling the morphology and properties of the fine hybrid films. It was found that compatibilisation of PEO-SiO 2 hybrid system is achieved exclusively with the use of γ-glycidyloxypropyltrimethoxysilane (GOTMS) coupling agent. (Author)

Growth and physiological responses of maize (Zea mays L.) to porous silica nanoparticles in soil

Energy Technology Data Exchange (ETDEWEB)

Suriyaprabha, R.; Karunakaran, G.; Yuvakkumar, R.; Prabu, P.; Rajendran, V., E-mail: veerajendran@gmail.com [K. S. Rangasamy College of Technology, Centre for Nano Science and Technology (India); Kannan, N. [K. S. Rangasamy College of Arts and Science, Department of Biotechnology (India)

2012-12-15

The present study aims to explore the effect of high surface area (360.85 m{sup 2} g{sup -1}) silica nanoparticles (SNPs) (20-40 nm) extracted from rice husk on the physiological and anatomical changes during maize growth in sandy loam soil at four concentrations (5-20 kg ha{sup -1}) in comparison with bulk silica (15-20 kg ha{sup -1}). The plant responses to nano and bulk silica treatments were analyzed in terms of growth characteristics, phyto compounds such as total protein, chlorophyll, and other organic compounds (gas chromatography-mass spectroscopy), and silica accumulation (high-resolution scanning electron microscopy). Growth characteristics were much influenced with increasing concentration of SNPs up to 15 kg ha{sup -1} whereas at 20 kg ha{sup -1}, no significant increments were noticed. Silica accumulation in leaves was high at 10 and 15 kg ha{sup -1} (0.57 and 0.82 %) concentrations of SNPs. The observed physiological changes show that the expression of organic compounds such as proteins, chlorophyll, and phenols favored to maize treated with nanosilica especially at 15 kg ha{sup -1} compared with bulk silica and control. Nanoscale silica regimes at 15 kg ha{sup -1} has a positive response of maize than bulk silica which help to improve the sustainable farming of maize crop as an alternative source of silica fertilizer.

Characterisation of silica derived from rice husk (Muar, Johor, Malaysia) decomposition at different temperatures

Science.gov (United States)

Azmi, M. A.; Ismail, N. A. A.; Rizamarhaiza, M.; W. M. Hasif. A. A., K.; Taib, H.

2016-07-01

Rice husk was thermally decomposed to yield powder composed of silica (SiO2). Temperatures of 700°C and 1000°C were chosen as the decomposition temperatures. X-Ray Diffraction (XRD), X-Ray Florescence (XRF), Fourier Transform Infrared (FTIR), and Field Emission Scanning Electron Microscope (FESEM) analyses were conducted on a synthetic silica powder (SS-SiO2) and the rice husk ash as for the comparative characterisation study. XRD analyses clearly indicated that the decomposed rice husk yielded silica of different nature which are Crystalline Rice Husk Silica (C-RHSiO2) and Amorphous Rice Husk Silica (A-RHSiO2). Moreover, it was found that SS-SiO2 was of Quartz phase, C-RHSiO2 was of Trydimite and Cristobalite. Through XRF detection, the highest SiO2 purity was detected in SS-SiO2 followed by C-RHSiO2 and A-RHSiO2 with purity percentages of 99.60%, 82.30% and 86.30% respectively. FTIR results clearly indicated silica (SiO2) bonding 1056, 1064, 1047, 777, 790 and 798 cm-1) increased as the crystallinity silica increased. The Cristobalite phase was detected in C-RH SiO2 at the wavelength of 620 cm-1. Morphological features as observed by FESEM analyses confirmed that, SS-SiO2 and C-RH SiO2 showed prominent coarse granular morphology.

Interactions between Food Additive Silica Nanoparticles and Food Matrices

Directory of Open Access Journals (Sweden)

Mi-Ran Go

2017-06-01

Full Text Available Nanoparticles (NPs have been widely utilized in the food industry as additives with their beneficial characteristics, such as improving sensory property and processing suitability, enhancing functional and nutritional values, and extending shelf-life of foods. Silica is used as an anti-caking agent to improve flow property of powered ingredients and as a carrier for flavors or active compounds in food. Along with the rapid development of nanotechnology, the sizes of silica fall into nanoscale, thereby raising concerns about the potential toxicity of nano-sized silica materials. There have been a number of studies carried out to investigate possible adverse effects of NPs on the gastrointestinal tract. The interactions between NPs and surrounding food matrices should be also taken into account since the interactions can affect their bioavailability, efficacy, and toxicity. In the present study, we investigated the interactions between food additive silica NPs and food matrices, such as saccharides, proteins, lipids, and minerals. Quantitative analysis was performed to determine food component-NP corona using HPLC, fluorescence quenching, GC-MS, and ICP-AES. The results demonstrate that zeta potential and hydrodynamic radius of silica NPs changed in the presence of all food matrices, but their solubility was not affected. However, quantitative analysis on the interactions revealed that a small portion of food matrices interacted with silica NPs and the interactions were highly dependent on the type of food component. Moreover, minor nutrients could also affect the interactions, as evidenced by higher NP interaction with honey rather than with a simple sugar mixture containing an equivalent amount of fructose, glucose, sucrose, and maltose. These findings provide fundamental information to extend our understanding about the interactions between silica NPs and food components and to predict the interaction effect on the safety aspects of food

Stress development in particulate, nano-composite and polymeric coatings

Science.gov (United States)

Jindal, Karan

2009-12-01

The main goal of this research is to study the stress, structural and mechanical property development during the drying of particulate coatings, nano-composite coatings and VOC compliant refinish clearcoats. The results obtained during this research establish the mechanism for the stress development during drying in various coating systems. Coating stress was measured using a controlled environment stress apparatus based on cantilever deflection principle. The stress evolution in alumina coatings made of 0.4 mum size alumina particles was studied and the effect of a lateral drying was investigated. The stress does not develop until the later stages of drying. A peak stress was observed during drying and the peak stress originates due to the formation of pendular rings between the particles. Silica nanocomposite coatings were fabricated from suspension of nano sized silicon dioxide particles (20 nm) and polyvinyl alcohol (PVA) polymer. The stress in silica nano-composite goes through maximum as the amount of polymer in the coating increases. The highest final stress was found to be ˜ 110MPa at a PVA content of 60 wt%. Observations from SEM, nitrogen gas adsorption, camera imaging, and nano-indentation were also studied to correlate the coatings properties during drying to measured stress. A model VOC compliant two component (2K) acrylic-polyol refinish clearcoat was prepared to study the effects of a new additive on drying, curing, rheology and stress development at room temperature. Most of the drying of the low VOC coatings occurred before appreciable (20%) crosslinking. Tensile stress developed in the same timeframe as drying and then relaxed over a longer time scale. Model low VOC coatings prepared with the additive had higher peak stresses than those without the additive. In addition, rheological data showed that the additive resulted in greater viscosity buildup during drying.

Biocompatibility assessment of rice husk-derived biogenic silica nanoparticles for biomedical applications

Energy Technology Data Exchange (ETDEWEB)

Alshatwi, Ali A., E-mail: alshatwi@ksu.edu.sa; Athinarayanan, Jegan; Periasamy, Vaiyapuri Subbarayan

2015-02-01

Synthetic forms of silica have low biocompatibility, whereas biogenic forms have myriad beneficial effects in current toxicological applications. Among the various sources of biogenic silica, rice husk is considered a valuable agricultural biomass material and a cost-effective resource that can provide biogenic silica for biomedical applications. In the present study, highly pure biogenic silica nanoparticles (bSNPs) were successfully harvested from rice husks using acid digestion under pressurized conditions at 120 °C followed by a calcination process. The obtained bSNPs were subjected to phase identification analysis using X-ray diffraction, which revealed the amorphous nature of the bSNPs. The morphologies of the bSNPs were observed using transmission electron microscopy (TEM), which revealed spherical particles 10 to 30 nm in diameter. Furthermore, the biocompatibility of the bSNPs with human lung fibroblast cells (hLFCs) was investigated using a viability assay and assessing cellular morphological changes, intracellular ROS generation, mitochondrial transmembrane potential and oxidative stress-related gene expression. Our results revealed that the bSNPs did not have any significant incompatibility in these in vitro cell-based approaches. These preliminary findings suggest that bSNPs are biocompatible, could be the best alternative to synthetic forms of silica and are applicable to food additive and biomedical applications. - Highlights: • Simple, rapid and convenient process • Amorphous and spherical with 10–30 nm size SiO{sub 2} nanoparticles were fabricated. • Biogenic silica nanoparticles showed biocompatibility. • bSNPs are an alternative to synthetic forms of silica.

Oxidation of nano-reinforced polyolefins

International Nuclear Information System (INIS)

Gutierrez Castro, G.G.

2010-11-01

Nano-composite materials attract search due to their improvements on barrier properties by incorporating low level of nano-filler of 5%w. Nowadays, organically modified montmorillonite (MMT-O) is the most used filler due to its high aspect ratio which permits stronger clay/polymer interactions. If nano-reinforced materials are highly performing, the ways in which clay presence affects polyolefin durability have not being subject of a rigorous study, thus they are not yet clear. Our goal was to examine unstabilized clay polypropylene and unstabilized clay polyethylene nano composites to get a better comprehension of the clay effects on their thermo-oxidation process under low temperatures. The effects induced by a dual physic-chemical nature of the clay were explored. The problem was tackled from both experimental and theoretical point of views for degradation process not controlled and controlled by oxygen diffusion (homogenous and heterogeneous respectively). It seems that MMT-O speeds up oxidation. This phenomenon was modeled by adding a catalytic reaction between metallic particles initially present in the MMT-O and hydroperoxide groups (main responsible of oxidation). Regarding the oxygen permeability two situations were confronted: for the clay polypropylene system a decrease of 45% of oxygen permeability was measured. On the other hand, no variation was found for the polyethylene case. This effect was attributed to the fact that polyethylene nano-composite reached a blend morphology less developed than those of the polypropylene nano-composite. Kinetics and oxidation products profiles across the sample thickness were simulated for both systems by coupling oxidation reactions with oxygen diffusion equations. For the polyethylene case, the effects induced by oxidation on molar mass and crystalline morphology were also simulated. Finally, based on a structure-property relationship, simulations of mechanic modulus profiles were performed for the heterogeneous

Morphology and nano-structure analysis of soot particles sampled from high pressure diesel jet flames under diesel-like conditions

Science.gov (United States)

Jiang, Hao; Li, Tie; Wang, Yifeng; He, Pengfei

2018-04-01

Soot particles emitted from diesel engines have a significant impact on the atmospheric environment. Detailed understanding of soot formation and oxidation processes is helpful for reducing the pollution of soot particles, which requires information such as the size and nano-structure parameters of the soot primary particles sampled in a high-temperature and high-pressure diesel jet flame. Based on the thermophoretic principle, a novel sampling probe minimally disturbing the diesel jet flame in a constant volume combustion vessel is developed for analysing soot particles. The injected quantity of diesel fuel is less than 10 mg, and the soot particles sampled by carriers with a transmission electron microscope (TEM) grid and lacey TEM grid can be used to analyse the morphologies of soot aggregates and the nano-structure of the soot primary particles, respectively. When the quantity of diesel fuel is more than 10 mg, in order to avoid burning-off of the carriers in higher temperature and pressure conditions, single-crystal silicon chips are employed. Ultrasonic oscillations and alcohol extraction are then implemented to obtain high quality soot samples for observation using a high-resolution transmission electron microscope. An in-house Matlab-based code is developed to extract the nano-structure parameters of the soot particles. A complete sampling and analysis procedure of the soot particles is provided to study the formation and oxidation mechanism of soot.

Fracture surface analysis on nano-SiO{sub 2}/epoxy composite

Energy Technology Data Exchange (ETDEWEB)

Zhao Rongguo [Institute of Fundamental Mechanics and Material Engineering, Xiangtan University, Hunan 411105 (China); Key Laboratory of Low Dimensional Materials and Application Technology, Xiangtan University, Ministry of Education, Hunan 411105 (China)], E-mail: zhaorongguo@xtu.edu.cn; Luo Wenbo [Institute of Fundamental Mechanics and Material Engineering, Xiangtan University, Hunan 411105 (China); Key Laboratory of Low Dimensional Materials and Application Technology, Xiangtan University, Ministry of Education, Hunan 411105 (China)

2008-06-15

Fracture surface morphologies of nano-SiO{sub 2}/epoxy composite with different weight percentage of SiO{sub 2} are investigated using scanning electron microscopy. Two types of curing agent, dimethylbenzanthracene (DMBA) and methyltetrahydrophthalic anhydride (MeTHPA), are individually used for preparing the composites. It is found that the fracture surface morphology of the composite cured by DMBA shows as radial striations, which suggests a rapid brittle fracture mode, while the fracture surface morphology of the composite cured by MeTHPA shows as regularly spaced 'rib' markings, which indicates a stick-slip motion during the fracture process. Furthermore, the uniaxial tensile behavior under constant loading rate and ambient temperature are investigated. It is shown that the elastic modulus of the composite cured by DMBA firstly increases, and then decreases with the mass fraction of nano-SiO{sub 2} particles, but the elongation of the composite cured by MeTHPA is reversed with increasing fraction of nano-SiO{sub 2} particles. For nano-SiO{sub 2}/epoxy composite cured with MeTHPA that possesses a suitable fraction of nano-SiO{sub 2}, an excellent synthetic mechanical property on elastic modulus and elongation is obtained.

Preparation of disk-like particles with micro/nano hierarchical structures.

Science.gov (United States)

Meng, Zhen; Yang, Wenbo; Chen, Pengpeng; Wang, Weina; Jia, Xudong; Xi, Kai

2013-10-15

A facile, reproductive method has been successfully developed to produce disk-like microparticles self-assembled from monodispersed hybrid silica nanoparticles under certain circumstance. The disk-like microparticles with micro/nano hierarchical structures could be obtained in large amount under a mild condition and further used to biomimetic design of the superhydrophobic surface of lotus leaf. After traditional surface modification with dodecyltrichlorosiliane, the static contact angle of water on the surface with micro/nano hierarchical structure could reach 168.8°. The method of surface modification could be further simplified by click reaction with the introduction of thiol groups under mild condition. The present strategy for constructing the surface with micro/nano hierarchical structures offers the advantage of simple and large area fabrication, which enables a variety of superhydrophobic applications. Copyright © 2013 Elsevier Inc. All rights reserved.

Preliminary Study of Fermented Tapioca for Synthesis of Carbon Nano tubes

International Nuclear Information System (INIS)

Nurulhuda Ismail; Ying, P.Y.

2011-01-01

Carbon nano tubes had been produced by various precursor such as gas (methane, carbon dioxide), oil (camphor oil, olive oil, and cooking oil) and alcohol. Different methods used for carbon nano tubes synthesis like arc discharge method, laser ablation method and chemical vapour deposition method. In this experiment, thermal chemical vapour deposition method was selected for carbon nano tubes synthesis. Starting material of fermented tapioca was used as carbon source for the process. Argon gas flow were controlled at around 10-15 bubbles per minute and deposition time around 20 to 30 minute. Others parameters such as temperature of furnace 1 and 2, amount of inoculum and catalyst have been studied. The asThermogravimetri (TGA) was used to determine the volatile temperature of the mixing catalyst and fermented tapioca extract. The grown carbon nano tubes morphology was characterized through Raman spectroscopy, scanning and Field Emission Scanning Electron Microscopy (FESEM) techniques. The surface morphology and uniformity of carbon nano tubes are reliant to parameters used. (author)

Deformation behavior of nano-porous polycrystalline silver. Part II: Simulations

International Nuclear Information System (INIS)

Zabihzadeh, S.; Cugnoni, J.; Duarte, L.I.; Van Petegem, S.; Van Swygenhoven, H.

2017-01-01

Three-dimensional finite element simulations of nano-porous silver structures are performed to understand the correlation between the porous morphology and the mechanical behavior. The nanostructures have been obtained from ptychographic X-ray computed tomography. The simulations allow distinguishing between the interplay and role of the ligament size, the pore morphology and the porosity, and therefore provide a better comprehension of the experimental observations. We show that the proposed model has a predictive character for mechanical behavior of nano-porous silver.

Modeling of phonon heat transfer in spherical segment of silica aerogel grains

Energy Technology Data Exchange (ETDEWEB)

Han, Ya-Fen; Xia, Xin-Lin, E-mail: xiaxl@hit.edu.cn; Tan, He-Ping, E-mail: tanheping@hit.edu.cn; Liu, Hai-Dong

2013-07-01

Phonon heat transfer in spherical segment of nano silica aerogel grains is investigated by the lattice Boltzmann method (LBM). For various sizes of grains, the temperature distribution and the thermal conductivity are obtained by the numerical simulation, in which the size effects of the gap surface are also considered. The results indicate that the temperature distribution in the silica aerogel grain depends strongly on the size. Both the decreases in the diameter of spherical segment and the ratio of the diameter of gap surface to the diameter of spherical segment reduce its effective thermal conductivity obviously. In addition, the phonon scattering at the boundary surfaces becomes more prominent when grain size decreases.

Modeling of phonon heat transfer in spherical segment of silica aerogel grains

International Nuclear Information System (INIS)

Han, Ya-Fen; Xia, Xin-Lin; Tan, He-Ping; Liu, Hai-Dong

2013-01-01

Phonon heat transfer in spherical segment of nano silica aerogel grains is investigated by the lattice Boltzmann method (LBM). For various sizes of grains, the temperature distribution and the thermal conductivity are obtained by the numerical simulation, in which the size effects of the gap surface are also considered. The results indicate that the temperature distribution in the silica aerogel grain depends strongly on the size. Both the decreases in the diameter of spherical segment and the ratio of the diameter of gap surface to the diameter of spherical segment reduce its effective thermal conductivity obviously. In addition, the phonon scattering at the boundary surfaces becomes more prominent when grain size decreases

Effect of Nanosilica Type on Properties of Polyethylene Terephthalane/Silica Nanocomposite

Directory of Open Access Journals (Sweden)

Mazeyar Parvinzadeh Gashti

2012-12-01

Full Text Available This research is carried out to study some properties of polyethylene terephthalaten (PET as one of the most important synthetic polymers used in textile industry. PET based nanocomposites containing three differently modified silica particles were prepared by melt compounding. The influence of type and amount of nanosilica on various properties of nanocomposite was studied by Fourier transform infrared spectroscopy, scanning electron microscopy, contact angle determination, optical microscopy, differential scanning calorimetry, thermal gravimetry analyzer and dynamic mechanical thermal analyzer. ATR results indicated that the interactions ofhydrophilic nanosilica mainly occur at the surface of nanocomposites. SEM was used to confirm the presence of silica on the surface of nanocomposites and it showed that surface properties depend on hydrophilicity of nanosilica. Studies on surface tension of nanocomposites showed that modified nanosilica particles have higher tendency to remain in bulk polymer as compared with unmodified one. Optical microscopy images from nanocomposites-containing silica illustrated the increment of thenumber of spherulites in the PET matrix with increases in silica percentage which were dependent on nano-silica type and content. Differential scanning calorimetry results of the nanocomposites showed a slight drop in the melting temperature compared to pure PET. The results obtained from thermal stability test showed that any improvement in thermal stability depends on the type of silica and dispersion of particles in polyethylene terephthalate. Moreover, the extent of interactions between nanosilica particles and polyethylene terephthatale chains affects on thermal stability of the composite.of the composite.

Silica biomineralization via the self-assembly of helical biomolecules.

Science.gov (United States)

Liu, Ben; Cao, Yuanyuan; Huang, Zhehao; Duan, Yingying; Che, Shunai

2015-01-21

The biomimetic synthesis of relevant silica materials using biological macromolecules as templates via silica biomineralization processes attract rapidly rising attention toward natural and artificial materials. Biomimetic synthesis studies are useful for improving the understanding of the formation mechanism of the hierarchical structures found in living organisms (such as diatoms and sponges) and for promoting significant developments in the biotechnology, nanotechnology and materials chemistry fields. Chirality is a ubiquitous phenomenon in nature and is an inherent feature of biomolecular components in organisms. Helical biomolecules, one of the most important types of chiral macromolecules, can self-assemble into multiple liquid-crystal structures and be used as biotemplates for silica biomineralization, which renders them particularly useful for fabricating complex silica materials under ambient conditions. Over the past two decades, many new silica materials with hierarchical structures and complex morphologies have been created using helical biomolecules. In this review, the developments in this field are described and the recent progress in silica biomineralization templating using several classes of helical biomolecules, including DNA, polypeptides, cellulose and rod-like viruses is summarized. Particular focus is placed on the formation mechanism of biomolecule-silica materials (BSMs) with hierarchical structures. Finally, current research challenges and future developments are discussed in the conclusion. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Preparation of Ag@mSiO{sub 2} and Pt@mSiO{sub 2}nano composites using trioctylmethyl ammonium hydrogen phthalate (TOMAHP) ionic liquid as reaction medium

Energy Technology Data Exchange (ETDEWEB)

Biswas, Sujoy, E-mail: sujoyb@barc.gov.in [Chemical Engineering Group, Bhabha Atomic Research Centre, Mumbai 400085 (India); Dasgupta, Kinshuk [Materials Group, Bhabha Atomic Research Centre, Mumbai 400085 (India); Bahadur, Jitendra [Solid State Physics Division, Bhabha Atomic Research Centre, Mumbai 400085 (India); Tewari, Raghavendra [Materials Group, Bhabha Atomic Research Centre, Mumbai 400085 (India); Mazumder, Subhasish [Solid State Physics Division, Bhabha Atomic Research Centre, Mumbai 400085 (India)

2016-09-15

A novel one step green chemistry approach utilizing trioctylmethyl ammonium hydrogen phthalate (TOMAHP), task specific ionic liquid has been attempted for synthesis of Ag and Pt nanoparticles supported on silica (Ag@mSiO{sub 2} and Pt@mSiO{sub 2}). Structure, size distribution and morphology of these nano-composite particles were evaluated using X-ray diffraction (XRD), transmission electron microscopy (TEM), small angle neutron scattering (SANS) as well as small angle X-ray scattering (SAXS) techniques. The XRD results show that Ag/Pt metal nanoparticles deposited on to SiO{sub 2} surface are face center cubic (fcc) in nature. The TEM and SAXS/SANS results show the morphology and size distributions of Ag and Pt nanoparticles loaded on to the surface of SiO{sub 2}. It has been found that Ag nanoparticles are well dispersed on to the SiO{sub 2} surface and are quite monodisperse in size, whereas Pt nanoparticles are quite polydisperse in size and forms aggregate or chain like structure on SiO{sub 2} surface containing primary nanoparticles of typical size range 3–7 nm. The stability of nanoparticles, which controls its dispersion on SiO{sub 2} substrate, has been discussed. - Graphical abstract: Mechanism for Ag@mSiO{sub 2} and Pt@mSiO{sub 2} nano composites in TOMAHP ionic liquid medium. - Highlights: • Novel methods for preparation of Pt@SiO{sub 2} and Ag@SiO{sub 2} nano composite in functionalized ionic liquid. • Pt@SiO{sub 2} and Ag@SiO{sub 2} nano composite are characterized using XRD, TEM as well as small angle x-ray scattering techniques. • The sizes of nano composite is <10 nm in size. • The method is simple one step, green chemical reduction method to prepare SiO{sub 2} support nano catalyst.

Development of nano SiO2 incorporated nano zinc phosphate coatings on mild steel

International Nuclear Information System (INIS)

Tamilselvi, M.; Kamaraj, P.; Arthanareeswari, M.; Devikala, S.; Selvi, J. Arockia

2015-01-01

Highlights: • Nano SiO 2 incorporated nano zinc phosphate coating on mild steel was developed. • Coatings showed enhanced corrosion resistance. • The nano SiO 2 is adsorbed on mild steel surface and become nucleation sites. • The nano SiO 2 accelerates the phosphating process. - Abstract: This paper reports the development of nano SiO 2 incorporated nano zinc phosphate coatings on mild steel at low temperature for achieving better corrosion protection. A new formulation of phosphating bath at low temperature with nano SiO 2 was attempted to explore the possibilities of development of nano zinc phosphate coatings on mild steel with improved corrosion resistance. The coatings developed were studied by Scanning Electron Microscopy (SEM), Energy-Dispersive X-ray Spectroscopy (EDX), X-ray Diffraction (XRD), Transmission Electron Microscopy (TEM) and Electrochemical measurements. Significant variation in the coating weight, morphology and corrosion resistance was observed as nano SiO 2 concentrations varied from 0.5–4 g/L. The results showed that, the nano SiO 2 in the phosphating solution changed the initial potential of the interface between mild steel substrate and phosphating solution and reduce the activation energy of the phosphating process, increase the nucleation sites and yielded zinc phosphate coatings of higher coating weight, greater surface coverage and enhanced corrosion resistance. Better corrosion resistance was observed for coatings derived from phosphating bath containing 1.5 g/L nano SiO 2 . The new formulation reported in the present study was free from Ni or Mn salts and had very low concentration of sodium nitrite (0.4 g/L) as accelerator

Molecular Organization Induced Anisotropic Properties of Perylene - Silica Hybrid Nanoparticles.

Science.gov (United States)

Sriramulu, Deepa; Turaga, Shuvan Prashant; Bettiol, Andrew Anthony; Valiyaveettil, Suresh

2017-08-10

Optically active silica nanoparticles are interesting owing to high stability and easy accessibility. Unlike previous reports on dye loaded silica particles, here we address an important question on how optical properties are dependent on the aggregation-induced segregation of perylene molecules inside and outside the silica nanoparticles. Three differentially functionalized fluorescent perylene - silica hybrid nanoparticles are prepared from appropriate ratios of perylene derivatives and tetraethyl orthosilicate (TEOS) and investigated the structure property correlation (P-ST, P-NP and P-SF). The particles differ from each other on the distribution, organization and intermolecular interaction of perylene inside or outside the silica matrix. Structure and morphology of all hybrid nanoparticles were characterized using a range of techniques such as electron microscope, optical spectroscopic measurements and thermal analysis. The organizations of perylene in three different silica nanoparticles were explored using steady-state fluorescence, fluorescence anisotropy, lifetime measurements and solid state polarized spectroscopic studies. The interactions and changes in optical properties of the silica nanoparticles in presence of different amines were tested and quantified both in solution and in vapor phase using fluorescence quenching studies. The synthesized materials can be regenerated after washing with water and reused for sensing of amines.

Synthesis of Pt-immobilized on silica and polystyrene-encapsulated silica and their applications as electrocatalysts in the proton exchange membrane fuel cell

International Nuclear Information System (INIS)

Yi, Sung-Chul; Kim, Chang Young; Jung, Chi Young; Jeong, Sung Hoon; Kim, Wha Jung

2011-01-01

Nano sized Pt particles were successfully immobilized onto SiO 2 and polystyrene-encapsulated silica core shell (SiO 2 @PS). To make the immobilization of Pt onto both silica and polystyrene-encapsulated silica core shell, SiO 2 was first functionalized with -NH 2 using 3-amino propyl trimethoxysilane (APTMS) while for core shell, the negatively charged surface of polystyrene (PS) was changed with positive charge by cationic surfactant such as cetyltrimethylammonium chloride (CTACl) to make the formation of SiO 2 shell on preformed PS sphere. Transmission electron micrograph (TEM) images shows that Pt nanoparticles immobilized onto SiO 2 and SiO 2 @PS were to be 3-4 nm without agglomeraiton. The energy dispersive spectroscope (EDS) shows that Pt contents on both SiO 2 and SiO 2 @PS were to be 21.45% and 20.28%, respectively. In case of Pt-SiO 2 @PS, it is believed that Pt should have been immobilized onto PS surface and pore within SiO 2 shell as well as SiO 2 surface. The MEA fabricated with Pt-SiO 2 @PS shows better cell performance than of Pt-SiO 2 .

Nano-roughening n-side surface of AlGaInP-based LEDs for increasing extraction efficiency

International Nuclear Information System (INIS)

Lee, Y.J.; Lu, T.C.; Kuo, H.C.; Wang, S.C.; Hsu, T.C.; Hsieh, M.H.; Jou, M.J.; Lee, B.J.

2007-01-01

A chemical wet etching technique is presented to form a nano-roughened surface with triangle-like morphology on n-side-up AlGaInP-based LEDs fabricated by adopting adhesive layer bonding scheme. A simple and commonly used H 3 PO 4 -based solution was applied for chemical wet etching. The morphology of nano-roughened surfaces is analyzed by the atomic force microscope (AFM) and significantly related to the enhancement factor of the LED output power. The output power shows 80% increase after optimizing the nano-roughened morphology of n-side surface, as compared to the ordinary flat surface LED

Preparation and characterization of nano gold supported over montmorillonite clays

International Nuclear Information System (INIS)

Suraja, P.V.; Binitha, N.N.; Yaakob, Z.; Silija, P.P.

2009-01-01

Full text: The use of montmorillonite clays as a matrix, or as a host, for obtaining intercalated/supported metal particles has potential applications in catalysis and other areas. The gold nanoparticles were obtained from the most common anionic gold precursor HAuCl 4 ·3H 2 O by deposition-precipitation (DP) methods. However, it is difficult to prepare nano scale gold catalysts supported on silica surfaces with lower isoelectric point (IEP). Homogeneous precipitation method using urea also fails on silica surfaces. Reasons for the inefficiency of these methods are the negative charge of the metal precursor as well as the support surface and the high pH required for depositing gold nanoparticles. In the present work, we use glucose as the reductant in the presence of stabilizer for preparation of nano gold supported on montmorillonite clay. Here there is no need of increasing the pH of the solution to reduce the Au 3+ ions. The prepared systems are characterized using various techniques such as using X-ray fluorescence (XRF), UV-Vis Diffuse reflectance spectra (DRS) and Fourier Transform infra red spectra (FTIR) to prove the efficiency of the present method. (author)

Morphological, Structural, and Electrical Characterization of Sol-Gel-Synthesized ZnO Nano rods

International Nuclear Information System (INIS)

Kashif, M.; Hashim, U.; Foo, K.L.; Ali, M.E.; Ali, M.E.; Ali, S.M.U.

2013-01-01

ZnO nano rods were grown on thermally oxidized p-type silicon substrate using sol-gel method. The SEM image revealed high-density, well-aligned, and perpendicular ZnO nano rods on the oxidized silicon substrate. The XRD profile confirmed the c-axis orientation of the nano rods. PL measurements showed the synthesized ZnO nano rods have strong ultraviolet (UV) emission. The electrical characterization was performed using interdigitated silver electrodes to investigate the stability in the current flow of the fabricated device under different ultraviolet (UV) exposure times. It was notified that a stable current flow was observed after 60 min of UV exposure. The determination of stable current flow after UV exposure is necessary for UV-based gas sensing and optoelectronic devices.

Nano-structural characteristics and optical properties of silver chiral nano-flower sculptured thin films

International Nuclear Information System (INIS)

Savaloni, Hadi; Haydari-Nasab, Fatemh; Malmir, Mariam

2011-01-01

Silver chiral nano-flowers with 3-, 4- and 5-fold symmetry were produced using oblique angle deposition method in conjunction with the rotation of sample holder with different speeds at different sectors of each revolution corresponding to symmetry order of the acquired nano-flower. Atomic force microscopy (AFM) and field emission scanning electron microscopy (FESEM), were employed to obtain morphology and nano-structure of the films. Optical characteristics of silver chiral nano-flower thin films were obtained using single beam spectrophotometer with both s- and p-polarization incident light at 30 o and 70 o incidence angles and at different azimuthal angles (φ). Optical spectra showed both TM (TDM (transverse dipole mode) and TQM (transverse quadruple mode)) and LM (longitudinal mode) Plasmon resonance peaks. For 3- and 4-fold symmetry chiral nano-flowers the s-polarization extinction spectra obtained at different azimuthal angles did not show significant change in the Plasmon peak position while 5-fold symmetry chiral nano-flower showed a completely different behavior, which may be the result of increased surface anisotropy, so when the φ angle is changed the s-polarization response from the surface can change more significantly than that for lower symmetries. In general, for 3-, 4- and 5-fold symmetry chiral nano-flowers a sharp peak at lower wavelengths ( o incidence angle.

Liquid phase deposition of silica: Thin films, colloids and fullerenes

Science.gov (United States)

Whitsitt, Elizabeth A.

Little research has been done to explore liquid phase deposition (LPD) of silica on non-planar substrates. This thesis proves that the seeded growth of silica colloids from fullerene and surfactant micelles is possible via LPD, as is the coating of individual single walled carbon nanotubes (SWNTs) and carbon fibers. Working on the premise that a molecular growth mechanism (versus colloidal/gel deposition) is valid for LPD, nanostructured substrates and specific chemical functional groups should act as "seeds," or templates, for silica growth. Seeded growth is confirmed by reactions of the growth solution with a range of surfactants and with materials with distinctive surface moieties. LPD promises lower production costs and environmental impact as compared to present methods of coating technology, because it is an inherently simple process, using low temperatures and inexpensive air-stable reactants. Silica is ubiquitous in materials science. Its applications range from thixotropic additives for paint to gate dielectrics in the semiconductor industry. Nano-structured coatings and thin films are integral in today's electronics industry and will become more vital as the size of electronics shrinks. With the incorporation of nanoparticles in future devices, the ability to deposit quality coatings with finely tuned properties becomes paramount. The methods developed herein have applications in fabricating insulators for use in the future molecular scale electronics industry. Additionally, these silica nanoparticles have applications as templates for use in photonics and fuel cell membrane production and lend strength and durability to composites.

Multi-morphological growth of nano-structured In{sub 2}Se{sub 3} by ambient pressure triethylene glycol based solution syntheses

Energy Technology Data Exchange (ETDEWEB)

Li, Tongfei; Wang, Jian; Lai, Junyun; Zheng, Xuerong; Liu, Weiyan; Ji, Junna [School of Materials Science and Engineering, Key Laboratory for Advanced Ceramics and Machining Technology of Ministry of Education, Tianjin University, Tianjin 300072 (China); Liu, Hui [School of Materials Science and Engineering, Hebei University of Technology, Tianjin 300401 (China); Jin, Zhengguo, E-mail: zhgjin@tju.edu.cn [School of Materials Science and Engineering, Key Laboratory for Advanced Ceramics and Machining Technology of Ministry of Education, Tianjin University, Tianjin 300072 (China)

2015-10-15

In{sub 2}Se{sub 3} nanoparticles, flower-like shaped and sheet-shaped nanocrystals were synthesized by a new, facile, ambient pressure triethylene glycol based solution chemical route using indium(III) chloride and selenium powder as precursors. The growing morphology, crystallization, chemical stoichiometry and light absorption property of the In{sub 2}Se{sub 3} products synthesized were characterized by TEM, HRTEM, FESEM, XRD, EDX and UV–vis–NIR measurements. Multi-morphological growth of the nano-structured In{sub 2}Se{sub 3} in triethylene glycol based solution syntheses with changed assisting agents and reaction styles was demonstrated. - Highlights: • Multimorphological growth of In{sub 2}Se{sub 3} was demonstrated based on solution chemistry. • A new, facile, low cost and fast air pressure TEG based solution process was used. • Nanoparticles, flower-like shaped and sheet-shaped nanocrystals were synthesized. • Morphology, crystallization, stoichiometry and light absorption was characterized. • Solution growth of β-In{sub 2}Se{sub 3} nanosheets was firstly reported by this submission.

Nano-porosity in silica reinforced methyltrimethoxysilane coatings studied by positron beam analysis

NARCIS (Netherlands)

Escobar Galindo, R.; Veen, A. van; Schut, H.; Falub, C.V.; Balkenende, A.R.; With, G. de; Hosson, J.Th.M. De

The porosity in particle reinforced sol-gel coatings has been studied. Silica particles (Ludox-TM40) are introduced into methyl silicate coatings to increase the hardness, the elastic modulus and the fracture toughness. The methyl silicate has a relatively low density (about 1.2 g/cm(2)), while the

Preparation of Multi-walled Carbon Nano tubes/ Natural Rubber Composite by Wet Mixing Method

International Nuclear Information System (INIS)

Azira Abdul Aziz; Azira Abdul Aziz; Che Su Mat Saad; Mohamad Rusop Mahmood

2011-01-01

Natural rubber/multi-walled carbon nano tubes (Nr/MWCNTs) nanocomposite is formed by incorporating nano tubes in a polymer solution and subsequently evaporating the solvent. Using this technique, nano tubes will be dispersed homogeneously in the NR matrix in an attempt to increase the mechanical properties of these nano composites. Mechanical test results show an increase in the tensile strength for up to 19 times in relation to pure NR. In addition to mechanical testing, the morphology of the MWNTs into NR was studied by Field Emission Scanning Electron Microscopy (FESEM) in order to understand the morphology of the resulting system. Slight shift noted from Raman analyses from each different wt. % of MWCNTs with the NR due to the stress transfer that indicates reinforcement of the nano tubes. (author)

Nano-modification to improve the ductility of cementitious composites

International Nuclear Information System (INIS)

Yeşilmen, Seda; Al-Najjar, Yazin; Balav, Mohammad Hatam; Şahmaran, Mustafa; Yıldırım, Gürkan; Lachemi, Mohamed

2015-01-01

Effect of nano-sized mineral additions on ductility of engineered cementitious composites (ECC) containing high volumes of fly ash was investigated at different hydration degrees. Various properties of ECC mixtures with different mineral additions were compared in terms of microstructural properties of matrix, fiber-matrix interface, and fiber surface to assess improvements in ductility. Microstructural characterization was made by measuring pore size distributions through mercury intrusion porosimetry (MIP). Hydration characteristics were assessed using thermogravimetric analysis/differential thermal analysis (TGA/DTA), and fiber-matrix interface and fiber surface characteristics were assessed using scanning electron microscopy (SEM) through a period of 90 days. Moreover, compressive and flexural strength developments were monitored for the same period. Test results confirmed that mineral additions could significantly improve both flexural strength and ductility of ECC, especially at early ages. Cheaper Nano-CaCO 3 was more effective compared to nano-silica. However, the crystal structure of CaCO 3 played a very important role in the range of expected improvements

Photocatalytic activity of self-assembled porous TiO2 nano-columns array fabricated by oblique angle sputter deposition

Science.gov (United States)

Shi, Pengjun; Li, Xibo; Zhang, Qiuju; Yi, Zao; Luo, Jiangshan

2018-04-01

A well-separated and oriented TiO2 nano-columns arrays with porous structure were fabricated by the oblique angle sputter deposition technique and subsequently annealing at 450 °C in Ar/O2 mixed atmosphere. The deposited substrate was firstly modified by a template of self-assembled close-packed arrays of 500 nm-diameter silica (SiO2) spheres. Scanning electronic microscopic (SEM) images show that the porous columnar nanostructure is formed as a result of the geometric shadowing effect and surface diffusion of the adatoms in oblique angle deposition (OAD). X-ray diffraction (XRD) measurements reveal that the physically OAD film with annealing treatment are generally mixed phase of rutile and anatase TiO2 polymorphic forms. The morphology induced absorbance and band gap tuning by different substrates was demonstrated by the UV–vis spectroscopy. The well-separated one-dimensional (1D) nano-columns array with specific large porous surface area is beneficial for charge separation in photocatalytic degradation. Compared with compact thin film, such self-assembled porous TiO2 nano-columns array fabricated by oblique angle sputter deposition performed an enhanced visible light induced photocatalytic activity by decomposing methyl orange (MO) solution. The well-designed periodic array-structured porous TiO2 films by using modified patterned substrates has been demonstrated significantly increased absorption edge in the UV-visible light region with a narrower optical band gap, which are expected to be favorable for application in photovoltaic, lithium-ion insertion and photocatalytic, etc.

Two-dimensional silica opens new perspectives

Science.gov (United States)

Büchner, Christin; Heyde, Markus

2017-12-01

In recent years, silica films have emerged as a novel class of two-dimensional (2D) materials. Several groups succeeded in epitaxial growth of ultrathin SiO2 layers using different growth methods and various substrates. The structures consist of tetrahedral [SiO4] building blocks in two mirror symmetrical planes, connected via oxygen bridges. This arrangement is called a silica bilayer as it is the thinnest 2D arrangement with the stoichiometry SiO2 known today. With all bonds saturated within the nano-sheet, the interaction with the substrate is based on van der Waals forces. Complex ring networks are observed, including hexagonal honeycomb lattices, point defects and domain boundaries, as well as amorphous domains. The network structures are highly tuneable through variation of the substrate, deposition parameters, cooling procedure, introducing dopants or intercalating small species. The amorphous networks and structural defects were resolved with atomic resolution microscopy and modeled with density functional theory and molecular dynamics. Such data contribute to our understanding of the formation and characteristic motifs of glassy systems. Growth studies and doping with other chemical elements reveal ways to tune ring sizes and defects as well as chemical reactivities. The pristine films have been utilized as molecular sieves and for confining molecules in nanocatalysis. Post growth hydroxylation can be used to tweak the reactivity as well. The electronic properties of silica bilayers are favourable for using silica as insulators in 2D material stacks. Due to the fully saturated atomic structure, the bilayer interacts weakly with the substrate and can be described as quasi-freestanding. Recently, a mm-scale film transfer under structure retention has been demonstrated. The chemical and mechanical stability of silica bilayers is very promising for technological applications in 2D heterostacks. Due to the impact of this bilayer system for glass science

Nano crystals-Related Synthesis, Assembly, and Energy Applications 2012

International Nuclear Information System (INIS)

Zou, B.; Yu, W.W.; Seo, J.; Zhu, T.; Hu, M.Z.

2012-01-01

During the past decades, nano crystals have attracted broad attention due to their unique shape- and size-dependent physical and chemical properties that differ drastically from their bulk counterparts. Hitherto, much effort has been dedicated to achieving rational controlling over the morphology, assembly, and related energy applications of the nano materials. Therefore, the ability to manipulate the morphology, size, and size distribution of inorganic nano materials is still an important goal in modern materials physics and chemistry. Especially, the world's demand for energy supply is causing a dramatic escalation of social and political unrest. Likewise, the environmental impact of the global climate change due to the combustion of fossil fuel is becoming increasingly alarming. These problems compel us to search for effective routes to build devices that can supply sustainable energy, with not only high efficiency but also environmental friendship. One of ways to relieve the energy crisis is to exploit devices based on renewable energy sources, such as solar energy and water power. Aiming at this exploration, the primary stage requires the design of appropriate strategies for the synthesis of high-quality nano crystals with respect to size uniformity and superior electrochemical performances. As a consequence, we organize the current special issue for Journal of Nano materials to provide the authors with a platform and readers with the latest achievements of nano crystals-related synthesis, assembly, and energy applications.

Effect of nano-fillers on the thermal conductivity of epoxy composites with micro-Al2O3 particles

International Nuclear Information System (INIS)

Gao, Zhifang; Zhao, Lei

2015-01-01

Highlights: • Nano-fillers were synthesized by a simple urea process. • Ternary filler system with synthesized nano-hybrid fillers was investigated. • Using of nano-hybrid filler for prevent nanofiller aggregation was presented. - Abstract: Nano-AlN particles, AlN/graphene nano-hybrids (AlN/GE) and AlN/carbon nanotubes nano-hybrids (AlN/CNTs) were prepared. The structures, morphologies of synthesized nano-materials were examined by X-ray diffraction (XRD), scanning electron microscope (SEM) and transmission electron microscope (TEM). The results showed that the morphologies of the synthesized nano-materials were obviously different. In addition, the thermal conductivity of epoxy composites could be effectively improved by adding the produced nano-fillers. Especially, the epoxy composite with AlN/GE nano-hybrids had the highest enhancement in thermal conductivity comparison to the pure epoxy. Moreover, the density of epoxy composites with the synthesized nano-fillers was decreased and the corresponding thermal stability was enhanced

Morphological and cytohistochemical evaluation of renal effects of cadmium-doped silica nanoparticles given intratracheally to rat

International Nuclear Information System (INIS)

Coccini, T; Roda, E; Manzo, L; Barni, S

2013-01-01

Renal morphological parameters were determined in rats intratracheally instilled with model cadmium-containing silica nanoparticles (Cd-SiNPs, 1mg/rat), also exploring whether their potential modifications would be associated with toxicogenomic changes. Cd-SiNP effects, evaluated 7 and 30 days post-exposure, were assessed by (i) histopathology (Haematoxylin/Eosin Staining), (ii) characterization of apoptotic features by TUNEL staining. Data were compared with those obtained by CdCl 2 (400μg/rat), SiNPs (600μg/rat), 0.1 ml saline. Area-specific cell apoptosis was observed in all treatment groups: cortex and inner medulla were the most affected regions. Apoptotic changes were apparent at 7 days post-exposure in both areas, and were still observable in inner medulla 30 days after treatment. Increase in apoptotic frequency was more pronounced in Cd-SiNP-treated animals compared to either CdCl 2 or SiNPs. Histological findings showed comparable alterations in the renal glomerular (cortex) architecture occurring in all treatment groups at both time-points considered. The glomeruli appeared often collapsed, showing condensed, packed mesangial and endothelial cells. Oedematous haemorrhagic glomeruli were also observed in Cd-SiNPs-treated animals. Bare SiNPs caused morphological and apoptotic changes without modifying the renal gene expression profile. These findings support the concept that multiple assays and an integrated testing strategy should be recommended to characterize toxicological responses to nanoparticles in mammalian systems.

Morphological and cytohistochemical evaluation of renal effects of cadmium-doped silica nanoparticles given intratracheally to rat

Science.gov (United States)

Coccini, T.; Roda, E.; Barni, S.; Manzo, L.

2013-04-01

Renal morphological parameters were determined in rats intratracheally instilled with model cadmium-containing silica nanoparticles (Cd-SiNPs, 1mg/rat), also exploring whether their potential modifications would be associated with toxicogenomic changes. Cd-SiNP effects, evaluated 7 and 30 days post-exposure, were assessed by (i) histopathology (Haematoxylin/Eosin Staining), (ii) characterization of apoptotic features by TUNEL staining. Data were compared with those obtained by CdCl2 (400μg/rat), SiNPs (600μg/rat), 0.1 ml saline. Area-specific cell apoptosis was observed in all treatment groups: cortex and inner medulla were the most affected regions. Apoptotic changes were apparent at 7 days post-exposure in both areas, and were still observable in inner medulla 30 days after treatment. Increase in apoptotic frequency was more pronounced in Cd-SiNP-treated animals compared to either CdCl2 or SiNPs. Histological findings showed comparable alterations in the renal glomerular (cortex) architecture occurring in all treatment groups at both time-points considered. The glomeruli appeared often collapsed, showing condensed, packed mesangial and endothelial cells. Oedematous haemorrhagic glomeruli were also observed in Cd-SiNPs-treated animals. Bare SiNPs caused morphological and apoptotic changes without modifying the renal gene expression profile. These findings support the concept that multiple assays and an integrated testing strategy should be recommended to characterize toxicological responses to nanoparticles in mammalian systems.

Mesoporous silica nanotubes hybrid membranes for functional nanofiltration

International Nuclear Information System (INIS)

El-Safty, Sherif A; Shahat, Ahmed; Mekawy, Moataz; Nguyen, Hoa; Warkocki, Wojciech; Ohnuma, Masato

2010-01-01

The development of nanofiltration systems would greatly assist in the production of well-defined particles and biomolecules with unique properties. We report a direct, simple synthesis of hexagonal silica nanotubes (NTs), which vertically aligned inside anodic alumina membranes (AAM) by means of a direct templating method of microemulsion phases with cationic surfactants. The direct approach was used as soft templates for predicting ordered assemblies of surfactant/silica composites through strong interactions within AAM pockets. Thus, densely packed NTs were successfully formed in the entirety of the AAM channels. These silica NTs were coated with layers of organic moieties to create a powerful technique for the ultrafine filtration. The resulting modified-silica NTs were chemically robust and showed affinity toward the transport of small molecular particles. The rigid silica NTs inside AAM channels had a pore diameter of ≤ 4 nm and were used as ultrafine filtration systems for noble metal nanoparticles (NM NPs) and semiconductor nanocrystals (SC NCs) fabricated with a wide range of sizes (1.0-50 nm) and spherical/pyramidal morphologies. Moreover, the silica NTs hybrid membranes were also found to be suitable for separation of biomolecules such as cytochrome c (CytC). Importantly, this nanofilter design retains high nanofiltration efficiency of NM NPs, SC NCs and biomolecules after a number of reuse cycles. Such retention is crucial in industrial applications.

Review on the Synthesis and Applications of Nano materials

International Nuclear Information System (INIS)

Liu, X.; Tang, Y.; Liang, B.; Zhong, Z.

2013-01-01

Recently, Fe 3 O 4 nano materials have attracted tremendous attention because of their favorable electric and magnetic properties. Fe 3 O 4 nano structures with various morphologies have been successfully synthesized and have been used in many fields such as lithium-ion batteries (LIBs), wastewater treatment, and magnetic resonance imaging (MRI) contrast agents. In this paper, we provide an in-depth discussion of recent development of Fe 3 O 4 nano materials, including their effective synthetic methods and potential applications.

Study of the influence of the silica source on the synthesis of the zeolite precursor MCM-22

International Nuclear Information System (INIS)

Barbosa, A.S.; Santos, E.R.F. dos; Leite, R.C.N.; Rodrigues, M.G.F.

2012-01-01

Zeolite MCM-22 precursors were synthesized under hydrothermal conditions in systems with hexamethyleneimine HMI as bulking agent (driver). Synthesis parameter, such as sources of silica (aerosil® and quartz) was modified to investigate the effects on the morphology and crystallization in precursor MCM-22 zeolite. The products were characterized by X-Ray Diffraction (XRD), Energy Dispersive Spectroscopy (EDX) and Scanning Electron Microscopy (SEM). According to, the X-ray diffraction showed the same characteristic peaks of zeolite MCM-22. It was found that the parameter in this work of synthesis, silica source, affects the hydrothermal synthesis of zeolite MCM-22 precursor. This can be evidenced by the different morphologies found using the different sources of silica. (author)

A multifunctional role of trialkylbenzenes for the preparation of aqueous colloidal mesostructured/mesoporous silica nanoparticles with controlled pore size, particle diameter, and morphology

Science.gov (United States)

Yamada, Hironori; Ujiie, Hiroto; Urata, Chihiro; Yamamoto, Eisuke; Yamauchi, Yusuke; Kuroda, Kazuyuki

2015-11-01

Both the pore size and particle diameter of aqueous colloidal mesostructured/mesoporous silica nanoparticles (CMSS/CMPS) derived from tetrapropoxysilane were effectively and easily controlled by the addition of trialkylbenzenes (TAB). Aqueous highly dispersed CMPS with large pores were successfully obtained through removal of surfactants and TAB by a dialysis process. The pore size (from 4 nm to 8 nm) and particle diameter (from 50 nm to 380 nm) were more effectively enlarged by the addition of 1,3,5-triisopropylbenzene (TIPB) than 1,3,5-trimethylbenzene (TMB), and the enlargement did not cause the variation of the mesostructure and particle morphology. The larger molecular size and higher hydrophobicity of TIPB than TMB induce the incorporation of TIPB into micelles without the structural change. When TMB was used as TAB, the pore size of CMSS was also enlarged while the mesostructure and particle morphology were varied. Interestingly, when tetramethoxysilane and TIPB were used, CMSS with a very small particle diameter (20 nm) with concave surfaces and large mesopores were obtained, which may strongly be related to the initial nucleation of CMSS. A judicious choice of TAB and Si sources is quite important to control the mesostructure, size of mesopores, particle diameter, and morphology.Both the pore size and particle diameter of aqueous colloidal mesostructured/mesoporous silica nanoparticles (CMSS/CMPS) derived from tetrapropoxysilane were effectively and easily controlled by the addition of trialkylbenzenes (TAB). Aqueous highly dispersed CMPS with large pores were successfully obtained through removal of surfactants and TAB by a dialysis process. The pore size (from 4 nm to 8 nm) and particle diameter (from 50 nm to 380 nm) were more effectively enlarged by the addition of 1,3,5-triisopropylbenzene (TIPB) than 1,3,5-trimethylbenzene (TMB), and the enlargement did not cause the variation of the mesostructure and particle morphology. The larger molecular size

Controllable synthesis of Ln3+ (Ln = Tb, Eu) doped zinc phosphate nano-/micro-structured materials: phase, morphology and luminescence properties

Science.gov (United States)

Yue, Dan; Lu, Wei; Li, Chunyang; Zhang, Xinlei; Liu, Chunxia; Wang, Zhenling

2014-01-01

Ln3+ (Ln = Tb, Eu) doped zinc phosphate tetrahydrate (ZPT:Ln3+) and ammonium zinc phosphate (AZP:Ln3+) nano-/micro-structured materials were synthesized in aqueous solution without the addition of any structure-directing agent. The phase structures, morphologies and luminescence properties of the as-synthesized samples were investigated by X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDX), transmission electron microscopy (TEM), photoluminescence (PL) spectroscopy and lifetime. These investigations indicate that different phosphate sources MnH(3-n)PO4 (M = NH4+ or Na+, n = 1, 2, 3) can lead to the altering of morphology from nanosheet to microflower, but have no significant effect on the phase structure of the samples. The microlump, nanosheet, and microflower (constructed by the primary microlumps or nanosheets) of orthorhombic ZPT:Ln3+ could be selectively prepared by adjusting the pH value from 3.5 to 7.0. A mixture of orthorhombic ZPT:Ln3+ and monoclinic AZP:Ln3+ with a microflower morphology was obtained when the pH value was adjusted to 8.0. Monoclinic AZP:Ln3+ microplate, microcube and nanoparticle morphologies were obtained at pH values of 8.5, 9.0 and 11.0 respectively. The phase transformation and growth mechanism of the diverse morphologies were proposed, and ZPT:Ln3+ (Ln3+ = Eu or Tb) samples exhibit red or green emission under the excitation of UV light.Ln3+ (Ln = Tb, Eu) doped zinc phosphate tetrahydrate (ZPT:Ln3+) and ammonium zinc phosphate (AZP:Ln3+) nano-/micro-structured materials were synthesized in aqueous solution without the addition of any structure-directing agent. The phase structures, morphologies and luminescence properties of the as-synthesized samples were investigated by X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDX), transmission electron microscopy (TEM), photoluminescence (PL) spectroscopy and lifetime. These

NanoTopoChip: High-throughput nanotopographical cell instruction.

Science.gov (United States)

Hulshof, Frits F B; Zhao, Yiping; Vasilevich, Aliaksei; Beijer, Nick R M; de Boer, Meint; Papenburg, Bernke J; van Blitterswijk, Clemens; Stamatialis, Dimitrios; de Boer, Jan

2017-10-15

Surface topography is able to influence cell phenotype in numerous ways and offers opportunities to manipulate cells and tissues. In this work, we develop the Nano-TopoChip and study the cell instructive effects of nanoscale topographies. A combination of deep UV projection lithography and conventional lithography was used to fabricate a library of more than 1200 different defined nanotopographies. To illustrate the cell instructive effects of nanotopography, actin-RFP labeled U2OS osteosarcoma cells were cultured and imaged on the Nano-TopoChip. Automated image analysis shows that of many cell morphological parameters, cell spreading, cell orientation and actin morphology are mostly affected by the nanotopographies. Additionally, by using modeling, the changes of cell morphological parameters could by predicted by several feature shape parameters such as lateral size and spacing. This work overcomes the technological challenges of fabricating high quality defined nanoscale features on unprecedented large surface areas of a material relevant for tissue culture such as PS and the screening system is able to infer nanotopography - cell morphological parameter relationships. Our screening platform provides opportunities to identify and study the effect of nanotopography with beneficial properties for the culture of various cell types. The nanotopography of biomaterial surfaces can be modified to influence adhering cells with the aim to improve the performance of medical implants and tissue culture substrates. However, the necessary knowledge of the underlying mechanisms remains incomplete. One reason for this is the limited availability of high-resolution nanotopographies on relevant biomaterials, suitable to conduct systematic biological studies. The present study shows the fabrication of a library of nano-sized surface topographies with high fidelity. The potential of this library, called the 'NanoTopoChip' is shown in a proof of principle HTS study which

Capture and separation of l-histidine through optimized zinc-decorated magnetic silica spheres.

Science.gov (United States)

Cardoso, Vanessa F; Sebastián, Víctor; Silva, Carlos J R; Botelho, Gabriela; Lanceros-Méndez, Senentxu

2017-09-01

Zinc-decorated magnetic silica spheres were developed, optimized and tested for the capture and separation of l-histidine. The magnetic silica spheres were prepared using a simple sol-gel method and show excellent magnetic characteristics, adsorption capacity toward metal ions, and stability in aqueous solution in a wide pH range. The binding capacity of zinc-decorated magnetic silica spheres to histidine proved to be strongly influenced by the morphology, composition and concentration of metal at the surface of the magnetic silica spheres and therefore these parameters should be carefully controlled in order to maximize the performance for protein purification purposes. Optimized zinc-decorated magnetic silica spheres demonstrate a binding capacity to l-histidine of approximately 44mgg -1 at the optimum binding pH buffer. Copyright © 2017 Elsevier B.V. All rights reserved.

Synthesis of wrinkled mesoporous silica and its reinforcing effect for dental resin composites.

Science.gov (United States)

Wang, Ruili; Habib, Eric; Zhu, X X

2017-10-01

The aim of this work is to explore the reinforcing effect of wrinkled mesoporous silica (WMS), which should allow micromechanical resin matrix/filler interlocking in dental resin composites, and to investigate the effect of silica morphology, loading, and compositions on their mechanical properties. WMS (average diameter of 496nm) was prepared through the self-assembly method and characterized by the use of the electron microscopy, dynamic light scattering, and the N 2 adsorption-desorption measurements. The mechanical properties of resin composites containing silanized WMS and nonporous smaller silica were evaluated with a universal mechanical testing machine. Field-emission scanning electron microscopy was used to study the fracture morphology of dental composites. Resin composites including silanized silica particles (average diameter of 507nm) served as the control group. Higher filler loading of silanized WMS substantially improved the mechanical properties of the neat resin matrix, over the composites loaded with regular silanized silica particles similar in size. The impregnation of smaller secondary silica particles with diameters of 90 and 190nm, denoted respectively as Si90 and Si190, increased the filler loading of the bimodal WMS filler (WMS-Si90 or WMS-Si190) to 60wt%, and the corresponding composites exhibited better mechanical properties than the control fillers made with regular silica particles. Among all composites, the optimal WMS-Si190- filled composite (mass ratio WMS:Si190=10:90, total filler loading 60wt%) exhibited the best mechanical performance including flexural strength, flexural modulus, compressive strength and Vickers microhardness. The incorporation of WMS and its mixed bimodal fillers with smaller silica particles led to the design and formulation of dental resin composites with superior mechanical properties. Copyright © 2017 The Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved.

Preparation of Silica Nanoparticles and Its Beneficial Role in Cementitious Materials

Directory of Open Access Journals (Sweden)

S. Ahalawat

2011-07-01

Full Text Available Spherical silica nanoparticles (n‐SiO2 with controllable size have been synthesized using tetraethoxysilane as starting material and ethanol as solvent by sol‐gel method. Morphology and size of the particles was controlled through surfactants. Sorbitan monolaurate, sorbitain monopalmitate and sorbitain monostearate produced silica nanoparticles of varying sizes (80‐150 nm, indicating the effect of chain length of the surfactant. Increase in chain length of non‐ionic surfactant resulted in decreasing particle size of silica nanoparticles. Further, the size of silica particles was also controlled using NH3 as base catalyst. These silica nanoparticles were incorporated into cement paste and their role in accelerating the cementitious reactions was investigated. Addition of silica nanoparticles into cement paste improved the microstructure of the paste and calcium leaching is significantly reduced as n‐SiO2 reacts with calcium hydroxide and form additional calcium‐ silicate‐hydrate (C‐S‐H gel. It was found that calcium hydroxide content in silica nanoparticles incorporated cement paste reduced ~89% at 1 day and up to ~60% at 28 days of hydration process. Synthesized silica particles and cement paste samples were characterized using scanning electron microscopy (SEM, powder X‐ray diffraction (XRD, infrared spectroscopy (IR and thermogravimetric analysis (TGA.

Facile synthesis of nano cauliflower and nano broccoli like hierarchical superhydrophobic composite coating using PVDF/carbon soot particles via gelation technique.

Science.gov (United States)

Sahoo, Bichitra Nanda; Balasubramanian, Kandasubramanian

2014-12-15

We have elucidated a cost effective fabrication technique to produce superhydrophobic polyvinylidene fluoride (PVDF/DMF/candle soot particle and PVDF/DMF/camphor soot particle composite) porous materials. The water repellent dry composite was formed by the interaction of non-solvent (methanol) into PVDF/carbon soot particles suspension in N,N-dimethylformamide (DMF). It is seen that longer quenching time effectively changes the surface morphology of dry composites. The nano broccoli like hierarchical microstructure with micro or nano scaled roughen surface was obtained for PVDF/DMF/camphor soot particle, which reveals water contact angle of 172° with roll off angle of 2°. However, composite coating of PVDF/DMF/candle soot particle shows nano cauliflower like hierarchical, which illustrates water contact angle of 169° with roll off angle of 3°. To elucidate the enhancement of water repellent property of PVDF composites, we further divulge the evolution mechanism of nano cauliflower and nano broccoli structure. In order to evaluate the water contact angle of PVDF composites, surface diffusion of water inside the pores is investigated. Furthermore, the addition of small amount of carbon soot particles in composite not only provides the crystallization of PVDF, but also leads to dramatical amendment of surface morphology which increases the surface texture and roughness for superhydrophobicity. Copyright © 2014 Elsevier Inc. All rights reserved.

1D Nano materials 2012

International Nuclear Information System (INIS)

Yanqiu Zhu, Y.; Ma, R.; Whitby, R.; Acquah, S.

2013-01-01

We witnessed an initial hyped period and enthusiasm on carbon nano tubes in the 1990s later went through a significant expansion into nano tubes of other materials (metal di chalcogenides, boron nitride, etc.) as well as various nano wires and nano rods. While much of the hype might have gone, the research on one-dimensional (1D) nano materials has matured as one of the most active research areas within the nano science and nano technology community, flourishing with ample, exciting, and new research opportunities. Just like any other research frontier, researchers working in the 1D nano materials field are constantly striving to develop new fundamental science as well as potential applications. It remains a common belief that versatility and tunability of 1D nano materials would challenge many new rising tasks coming from our resource and energy demanding modern society. The traditional semiconductor industry has produced so many devices and systems from transistors, sensors, lasers, and LEDs to more sophisticated solar panels, which are now part of our daily lives. By down sizing the core components or parts to 1D form, one might wonder how fundamentally the dimensionality and morphology would impact the device performance, this is, as always, requiring us to fully understand the structure-property relationship in 1D nano materials. It may be equally crucial in connecting discovery-driven fundamental science to market-driven technology industry concerning potentially relevant findings derived from these novel materials. The importance of a platform that allows active researchers in this field to present their new development in a timely and efficient manner is therefore self-evident. Following the success of two early special issues devoted to 1D nano materials, this is the third one in a row organized by the same group of guest editors, attesting that such a platform has been well received by the readers

The Effect of Aging and Silanization on the Mechanical Properties of Fumed Silica-based Dental Composite

Directory of Open Access Journals (Sweden)

Khaje S

2015-12-01

Full Text Available Statement of Problem: Mechanical strength and durability of dental composites are the main topics studied in this field of science today. This study examined fumed silica-based composite as a strong and durable restorative material through flexural and cycling test methods. Objectives: The purpose of this study was to evaluate the effect of silanization, ageing, cycling and hybridizing on mechanical properties of fumed silica-based resin composite. Materials and Methods: Composites were made of light-cured copolymer based on Bisphenol A glycolmethacrylate (Bis-GMA and Triethylene glycoldimethacrylate (TEGDMA at proportion of 50:50 which reinforced by fumed silica filler. For each composite sample, 5 specimen bars were made using Teflon mould (2 x 2 x 25 mm3. The samples with 12 wt% fumed silica (FS were considered as a base line group. The samples were exposed to cyclic cold water (FS-CCW and hot water (FS-CHW. The effect of silanization and adding more filler was studied together with samples containing 12 wt% (FS-S (12, 16 wt% (FS-S (16 and 20 wt% (FS-S (20 fumed silica filler. The filler was silanized with (γ-MPS. The degree of conversion was assessed with Fourier Transform Infra-Red spectroscopy. Flexural properties were evaluated with the Three-Point Bending test. Flexural data were analyzed with Excel software. Hardness was measured with an Atomic Force Microscope (AFM. Results: The degree of conversion of the resin reached 74% within 24 hrs. Salinization allowed more filler to be wetted by resin. Addition of silanized particles from sample FS-S (12 to sample FS-S (20 improved the mechanical strength. Hybridizing fumed silica with nano-silica (FS-N had no significant effect on the strength, but nano-hardness improved greatly. Ageing and cycling had adverse effects on the strength of the sample FS. The flexural strength of FS-CHW was 72% less than FS sample. Conclusions: Sample FS-N with low diluent and filler percentage complied with the

Influence of layer eccentricity on the resonant properties of cylindrical active coated nano-particles

DEFF Research Database (Denmark)

Thorsen, R. O.; Arslanagic, Samel

2015-01-01

We report on the influence of the layer eccentricity on the resonant properties of active coated nano-particles made of a silver core and gain impregnated silica shell illuminated by a near-by magnetic line source. For a fixed over-all size of the particle, designs with small and large cores...

Tapered silicon core fibers with nano-spikes for optical coupling via spliced silica fibers

OpenAIRE

Ren, Haonan; Aktas, Ozan; Franz, Yohann; Runge, Antoine; Hawkins, Thomas A.; Ballato, John; Gibson, Ursula; Peacock, Anna

2017-01-01

Abstract: Reported here is the fabrication of tapered silicon core fibers possessing a nanospike input that facilitates their seamless splicing to conventional single mode fibers. A proofof-concept 30 µm cladding diameter fiber-based device is demonstrated with nano-spike coupling and propagation losses below 4 dB and 2 dB/cm, respectively. Finite-elementmethod-based simulations show that the nano-spike coupling losses could be reduced to below 1 dB by decreasing the cladding diameters down t...

Characterisation of silica derived from rice husk (Muar, Johor, Malaysia) decomposition at different temperatures

Energy Technology Data Exchange (ETDEWEB)

Azmi, M. A.; Ismail, N. A. A.; Rizamarhaiza, M.; Hasif, W. M. K. A. A.; Taib, H., E-mail: hariati@uthm.edu.my [Faculty of Mechanical and Manufacturing Engineering, Universiti Tun Hussein Onn Malaysia, 86400 Batu Pahat, Johor (Malaysia)

2016-07-19

Rice husk was thermally decomposed to yield powder composed of silica (SiO{sub 2}). Temperatures of 700°C and 1000°C were chosen as the decomposition temperatures. X-Ray Diffraction (XRD), X-Ray Florescence (XRF), Fourier Transform Infrared (FTIR), and Field Emission Scanning Electron Microscope (FESEM) analyses were conducted on a synthetic silica powder (SS-SiO{sub 2}) and the rice husk ash as for the comparative characterisation study. XRD analyses clearly indicated that the decomposed rice husk yielded silica of different nature which are Crystalline Rice Husk Silica (C-RHSiO{sub 2}) and Amorphous Rice Husk Silica (A-RHSiO{sub 2}). Moreover, it was found that SS-SiO{sub 2} was of Quartz phase, C-RHSiO{sub 2} was of Trydimite and Cristobalite. Through XRF detection, the highest SiO{sub 2} purity was detected in SS-SiO{sub 2} followed by C-RHSiO{sub 2} and A-RHSiO{sub 2} with purity percentages of 99.60%, 82.30% and 86.30% respectively. FTIR results clearly indicated silica (SiO{sub 2}) bonding 1056, 1064, 1047, 777, 790 and 798 cm{sup −1}) increased as the crystallinity silica increased. The Cristobalite phase was detected in C-RH SiO{sub 2} at the wavelength of 620 cm{sup −1}. Morphological features as observed by FESEM analyses confirmed that, SS-SiO{sub 2} and C-RH SiO{sub 2} showed prominent coarse granular morphology.

Gamma radiation effects on nano composites of Ag nanoparticles in Zn O matrices

International Nuclear Information System (INIS)

Villasenor C, L. S.

2015-01-01

The study of gamma radiation effects in nano composites of silver nanoparticles in a Zn O matrix has been performed in this work. First, silver nanoparticles (AgNPs) were synthesized by colloidal methods, with two different mean average sizes, 48 nm and 24 nm respectively. These nanoparticles were characterized by transmission electron microscopy (Tem) and UV-Vis spectroscopy (UV-Vis). Then, with the synthesized AgNPs, nano composites in a matrix of Zn O were prepared. The first nano composite was prepared with the 48 nm AgNPs at 9.5 weight % of silver (Ag) and the second nano composite with the 24 nm nanoparticles at 1.0 weight % of Ag. Both nano composites were analyzed by scanning electron microscopy (Sem). The formation of the Zn O phase in the nano composite was corroborated through X-ray diffraction analysis. It was observed that the presence of AgNPs during the formation of the AgNPs/Zn O nano composite modified the size and morphology of the structures obtained compared to those of the pure Zn O without nanoparticles, however both exhibit a radial structure. Then, the nano composite at 9.5 weight % of Ag was irradiated with gamma rays at doses of 1, 20 and 50 kGy. Samples were analyzed by Sem and the Bet technique, before and after being irradiated, in order to determine the effect of gamma radiation in the morphology, porosity and surface area of the studied material. Even when there are changes in porosity and Surface area, this difference is not very significant for some applications, however it will have to be considered during the design of a specific application of the nano composites. On the other hand, no morphology modifications were identified on the samples irradiated at the studied doses, with the electron microscopy techniques used. (Author)

Biological Applications and Transmission Electron Microscopy Investigations of Mesoporous Silica Nanoparticles

Energy Technology Data Exchange (ETDEWEB)

Trewyn, Brian G. [Iowa State Univ., Ames, IA (United States)

2006-01-01

The research presented and discussed within involves the development of novel biological applications of mesoporous silica nanoparticles (MSN) and an investigation of mesoporous material by transmission electron microscopy (TEM). Mesoporous silica nanoparticles organically functionalized shown to undergo endocytosis in cancer cells and drug release from the pores was controlled intracellularly and intercellularly. Transmission electron microscopy investigations demonstrated the variety of morphologies produced in this field of mesoporous silica nanomaterial synthesis. A series of room-temperature ionic liquid (RTIL) containing mesoporous silica nanoparticle (MSN) materials with various particle morphologies, including spheres, ellipsoids, rods, and tubes, were synthesized. By changing the RTIL template, the pore morphology was tuned from the MCM-41 type of hexagonal mesopores to rotational moire type of helical channels, and to wormhole-like porous structures. These materials were used as controlled release delivery nanodevices to deliver antibacterial ionic liquids against Escherichia coli K12. The involvement of a specific organosiloxane function group, covalently attached to the exterior of fluorescein doped mesoporous silica nanoparticles (FITC-MSN), on the degree and kinetics of endocytosis in cancer and plant cells was investigated. The kinetics of endocystosis of TEG coated FITC-MSN is significantly quicker than FITC-MSN as determined by flow cytometry experiments. The fluorescence confocal microscopy investigation showed the endocytosis of TEG coated-FITC MSN triethylene glycol grafted fluorescein doped MSN (TEG coated-FITC MSN) into both KeLa cells and Tobacco root protoplasts. Once the synthesis of a controlled-release delivery system based on MCM-41-type mesoporous silica nanorods capped by disulfide bonds with superparamagnetic iron oxide nanoparticles was completed. The material was characterized by general methods and the dosage and kinetics of the

[Biomimetic mineralization of rod-like cellulose nano-whiskers and spectrum analysis].

Science.gov (United States)

Qu, Ping; Wang, Xuan; Cui, Xiao-xia; Zhang, Li-ping

2012-05-01

Cellulose nano-whiskers/nano-hydroxyapatite composite was prepared with biomimetic mineralization using rod-like cellulose nano-whiskers as template. The cellulose nano-whiskers and cellulose nano-whiskers/nano-hydroxyapatite composite were characterized by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS) and scanning electron microscope-energy dispersive analysis of X-rays (SEM-EDXA). Variation and distribution of carbon, oxygen, calcium, and phosphorus in the composites were studied. The morphologies and growth mechanism of nano-hydroxyapatite were analyzed. The results showed that nano-hydroxyapatite was formed on the surface of cellulose nano-whiskers; the carbon-oxygen ratio of cellulose nano-whiskers and cellulose nano-whiskers/nano-hydroxyapatite composite was 1.81 and 1.54, respectively; the calcium-phosphorus ratio of the composite was 1.70. The nucleation of nano-hydroxyapatite was around the hydroxyl groups of cellulose nano-whiskers. It is suggested that there is coordination between the hydroxyl groups of cellulose nano-whiskers and calcium ions of nano-hydroxyapatite. The nano-hydroxyapatite can distribute in the matrix of cellulose nano-whiskers. From the atomic force microscope (AFM) images, we can see that the diameter of the spherical nano-hydroxyapatite particles was about 20 nm.

Optical properties study of nano-composite filled D shape photonic crystal fibre

Directory of Open Access Journals (Sweden)

R. Udaiyakumar

2018-06-01

Full Text Available With the nano-composite materials gaining momentum in the optical field, a new nano-composite filled D shape Photonic Crystal Fiber (PCF is designed and the various optical properties are investigated with help of Finite Element Method. In the proposed structure the D-shape PCF is made up of silica with embedded silver nanoparticles and air holes are distributed along the fibre. The designed fibre shows various optical properties such as dispersion, birefringence, beat length and loss with respect to wavelength and compared with different filling factor like 0.1, 0.3 and 0.5. From our estimation and comparative analysis, it has been proved that the fibre loss has been decreased with increasing filling factor. Further this also showed flat dispersion at maximum filling factor. Keywords: Nanoparticles, Nano-composite, Dispersion, Birefringence, Beat length

Synthesis of silver nanoparticles deposited on silica by γ-irradiation and preparation of PE/Ag nano compound masterbatches

Science.gov (United States)

Nguyen, Thi Kim Lan; Trinh Nguyen, Thuy Ai; Phu Dang, Van; Duy Nguyen, Ngoc; Le, Anh Quoc; Hien Nguyen, Quoc

2013-12-01

Silver nanoparticles (AgNPs) deposited on silica were synthesized by gamma Co-60 irradiation of Ag+ dispersion in silica/ethanol/water mixture (9/80/20:w/v/v). The reduction of Ag+ is occurred by hydrated electron (e-aq) and hydrogen atom (H•) generated during radiolysis of ethanol/water. The conversion doses (Ag+ → Ag0) were determined by UV-Vis spectroscopy. The synthesized AgNPs/silica were characterized by transmission electron microscopy (TEM) and x-ray diffraction (XRD), which showed the size of AgNPs to be in the range of 5-40 nm for Ag+ concentrations from 5 to 20 mM. Masterbatches of PE/AgNPs/silica compound with silver content from 250 to 1000 mg kg-1 were also prepared. These masterbatches can be suitably used for various applications such as antimicrobial food containers and packing films, etc.

Evaluation of the Morphology and Osteogenic Potential of Titania-Based Electrospun Nanofibers

Directory of Open Access Journals (Sweden)

Xiaokun Wang

2012-01-01

Full Text Available Submicron-scale titania-based ceramic fibers with various compositions have been prepared by electrospinning. The as-prepared nanofibers were heat-treated at 700°C for 3 h to obtain pure inorganic fiber meshes. The results show that the diameter and morphology of the nanofibers are affected by starting polymer concentration and sol-gel composition. The titania and titania-silica nanofibers had the average diameter about 100–300 nm. The crystal phase varied from high-crystallized rutile-anatase mixed crystal to low-crystallized anatase with adding the silica addition. The morphology and crystal phase were evaluated by SEM and XRD. Bone-marrow-derived mesenchymal stem cells were seeded on titania-silica 50/50 fiber meshes. Cell number and early differentiation marker expressions were analyzed, and the results indicated osteogenic potential of the titania-silica 50/50 fiber meshes.

Synthesis and Properties of Carbon Nanotube-Grafted Silica Nanoarchitecture-Reinforced Poly(Lactic Acid

Directory of Open Access Journals (Sweden)

Yao-Wen Hsu

2017-07-01

Full Text Available A novel nanoarchitecture-reinforced poly(lactic acid (PLA nanocomposite was prepared using multi-walled carbon nanotube (MWCNT-grafted silica nanohybrids as reinforcements. MWCNT-grafted silica nanohybrids were synthesized by the generation of silica nanoparticles on the MWCNT surface through the sol-gel technique. This synthetic method involves organo-modified MWCNTs that are dispersed in tetrahydrofuran, which incorporates tetraethoxysilane that undergoes an ultrasonic sol-gel process. Gelation yielded highly dispersed silica on the organo-modified MWCNTs. The structure and properties of the nanohybrids were established using 29Si nuclear magnetic resonance, Raman spectroscopy, wide-angle X-ray diffraction, thermogravimetric analysis, and transmission electron microscopy. The resulting MWCNT nanoarchitectures were covalently assembled into silica nanoparticles, which exhibited specific and controllable morphologies and were used to reinforce biodegradable PLA. The tensile strength and the heat deflection temperature (HDT of the PLA/MWCNT-grafted silica nanocomposites increased when the MWCNT-grafted silica was applied to the PLA matrix; by contrast, the surface resistivity of the PLA/MWCNT-grafted silica nanocomposites appeared to decline as the amount of MWCNT-grafted silica in the PLA matrix increased. Overall, the reinforcement of PLA using MWCNT-grafted silica nanoarchitectures was efficient and improved its mechanical properties, heat resistance, and electrical resistivity.

Rational Design and Synthesis of Carboxylate Gemini Surfactants with an Excellent Aggregate Behavior for Nano-La2O3 Morphology-Controllable Preparation.

Science.gov (United States)

Liao, Xueming; Gao, Zhinong; Xia, Yan; Niu, Fei; Zhai, Wenzhong

2017-04-04

A series of carboxylate gemini surfactants (CGS, C n -Φ-C n , n = 12, 14, 16, 18) with diphenyl ketone as a spacer group were prepared using a simple and feasible synthetic method. These CGS exhibited an excellent surface activity with extremely low critical micelle concentration (CMC) value (approximately 10 -5 mol/L), good performance in reducing surface tension (nearly 30 mN/m), and the ability of molecular self-assembly into different aggregate morphologies via adjusting the concentrations, which is attributed to the introduction of diphenyl ketone and carboxylic acid ammonium salt in the molecular structure. Moreover, the surface activity and self-assembly ability of CGS were further optimized by tuning the length of the tail chain. These excellent properties imply that CGS can be a soft template to prepare nanomaterials, especially in morphology-controllable synthesis. By adjusting the concentration of one of CGS (C 12 -Φ-C 12 ), nano-La 2 O 3 particles with diverse morphologies were obtained, including spherical shape, bead-chain shape, rod shape, velvet-antler shape, cedar shape, and bowknot shape. This work offers a vital insight into the rational design of template agents for the development of morphology-controllable nanomaterials.

Ordered nanoporous silica as carriers for improved delivery of water insoluble drugs: a comparative study between three dimensional and two dimensional macroporous silica

Directory of Open Access Journals (Sweden)

Wang Y

2013-10-01

Full Text Available Ying Wang, Qinfu Zhao, Yanchen Hu, Lizhang Sun, Ling Bai, Tongying Jiang, Siling WangDepartment of Pharmaceutics, Shenyang Pharmaceutical University, Liaoning Province, People’s Republic of ChinaAbstract: The goal of the present study was to compare the drug release properties and stability of the nanoporous silica with different pore architectures as a matrix for improved delivery of poorly soluble drugs. For this purpose, three dimensional ordered macroporous (3DOM silica with 3D continuous and interconnected macropores of different sizes (200 nm and 500 nm and classic mesoporous silica (ie, Mobil Composition of Matter [MCM]-41 and Santa Barbara Amorphous [SBA]-15 with well-ordered two dimensional (2D cylindrical mesopores were successfully fabricated and then loaded with the model drug indomethacin (IMC via the solvent deposition method. Scanning electron microscopy (SEM, N2 adsorption, differential scanning calorimetry (DSC, and X-ray diffraction (XRD were applied to systematically characterize all IMC-loaded nanoporous silica formulations, evidencing the successful inclusion of IMC into nanopores, the reduced crystallinity, and finally accelerated dissolution of IMC. It was worth mentioning that, in comparison to 2D mesoporous silica, 3DOM silica displayed a more rapid release profile, which may be ascribed to the 3D interconnected pore networks and the highly accessible surface areas. The results obtained from the stability test indicated that the amorphous state of IMC entrapped in the 2D mesoporous silica (SBA-15 and MCM-41 has a better physical stability than in that of 3DOM silica. Moreover, the dissolution rate and stability of IMC loaded in 3DOM silica was closely related to the pore size of macroporous silica. The colorimetric 3-(4,5-Dimethylthiazol-2-yl-2,5-diphenyltetrazolium bromide (MTT and Cell Counting Kit (CCK-8 assays in combination with direct morphology observations demonstrated the good biocompatibility of nanoporous

Hydrothermal synthesis of meso porous silica MCM-41 using commercial sodium silicate

International Nuclear Information System (INIS)

Melendez O, H. I.; Mercado S, A.; Garcia C, L. A.; Castruita, G.; Perera M, Y A.

2013-01-01

In this work, ordered meso porous silica MCM-41 was prepared by hydrothermal synthesis using industrial-grade sodium silicate (Na 2 SiO 3 ) as silica source, hexadecyltrimethyl-ammonium bromide (CTAB) as template agent and ethyl acetate as ph regulator. The influence of CTAB/SiO 2 molar ratio, reaction time, aging temperature, and co-surfactant type on the structural and morphological properties of the obtained silica was studied. The products were characterized by X-ray diffraction, scanning electron microscopy, transmission electron microscopy and nitrogen adsorption-desorption isotherms. Ordered meso porous MCM-41 silica was obtained at 80 C by using a range of CTAB/SiO 2 molar ratio from 0.35 to 0.71 and reaction times up to 72 h and isopropanol (i-Pr OH) as co-surfactant. (Author)

A morphogram for silica-witherite biomorphs and its application to microfossil identification in the early earth rock record.

Science.gov (United States)

Rouillard, J; García-Ruiz, J-M; Gong, J; van Zuilen, M A

2018-05-01

Archean hydrothermal environments formed a likely site for the origin and early evolution of life. These are also the settings, however, were complex abiologic structures can form. Low-temperature serpentinization of ultramafic crust can generate alkaline, silica-saturated fluids in which carbonate-silica crystalline aggregates with life-like morphologies can self-assemble. These "biomorphs" could have adsorbed hydrocarbons from Fischer-Tropsch type synthesis processes, leading to metamorphosed structures that resemble carbonaceous microfossils. Although this abiogenic process has been extensively cited in the literature and has generated important controversy, so far only one specific biomorph type with a filamentous shape has been discussed for the interpretation of Archean microfossils. It is therefore critical to precisely determine the full distribution in morphology and size of these biomorphs, and to study the range of plausible geochemical conditions under which these microstructures can form. Here, a set of witherite-silica biomorph synthesis experiments in silica-saturated solutions is presented, for a range of pH values (from 9 to 11.5) and barium ion concentrations (from 0.6 to 40 mmol/L BaCl 2 ). Under these varying conditions, a wide range of life-like structures is found, from fractal dendrites to complex shapes with continuous curvature. The size, spatial concentration, and morphology of the biomorphs are strongly controlled by environmental parameters, among which pH is the most important. This potentially limits the diversity of environments in which the growth of biomorphs could have occurred on Early Earth. Given the variety of the observed biomorph morphologies, our results show that the morphology of an individual microstructure is a poor criterion for biogenicity. However, biomorphs may be distinguished from actual populations of cellular microfossils by their wide, unimodal size distribution. Biomorphs grown by diffusion in silica gel can

Hydrothermal stability of silica, hybrid silica and Zr-doped hybrid silica membranes

NARCIS (Netherlands)

ten Hove, Marcel; Luiten-Olieman, Mieke W.J.; Huiskes, Cindy; Nijmeijer, Arian; Winnubst, Louis

2017-01-01

Hybrid silica membranes have demonstrated to possess a remarkable hydrothermal stability in pervaporation and gas separation processes allowing them to be used in industrial applications. In several publications the hydrothermal stability of pure silica or that of hybrid silica membranes are

Synthesis of silver nanoparticles deposited on silica by γ-irradiation and preparation of PE/Ag nano compound masterbatches

International Nuclear Information System (INIS)

Nguyen, Thi Kim Lan; Dang, Van Phu; Nguyen, Ngoc Duy; Le, Anh Quoc; Nguyen, Quoc Hien; Nguyen, Thuy Ai Trinh

2013-01-01

Silver nanoparticles (AgNPs) deposited on silica were synthesized by gamma Co-60 irradiation of Ag + dispersion in silica/ethanol/water mixture (9/80/20:w/v/v). The reduction of Ag + is occurred by hydrated electron (e − aq ) and hydrogen atom (H • ) generated during radiolysis of ethanol/water. The conversion doses (Ag + → Ag 0 ) were determined by UV–Vis spectroscopy. The synthesized AgNPs/silica were characterized by transmission electron microscopy (TEM) and x-ray diffraction (XRD), which showed the size of AgNPs to be in the range of 5–40 nm for Ag + concentrations from 5 to 20 mM. Masterbatches of PE/AgNPs/silica compound with silver content from 250 to 1000 mg kg −1 were also prepared. These masterbatches can be suitably used for various applications such as antimicrobial food containers and packing films, etc. (paper)

Fumed silica. Fumed silica

Energy Technology Data Exchange (ETDEWEB)

Sukawa, T.; Shirono, H. (Nippon Aerosil Co. Ltd., Tokyo (Japan))

1991-10-18

The fumed silica is explained in particulate superfineness, high purity, high dispersiveness and other remarkable characteristics, and wide application. The fumed silica, being presently produced, is 7 to 40nm in average primary particulate diameter and 50 to 380m{sup 2}/g in specific surface area. On the surface, there coexist hydrophilic silanol group (Si-OH) and hydrophobic siloxane group (Si-O-Si). There are many characteristics, mutually different between the fumed silica, made hydrophobic by the surface treatment, and untreated hydrophilic silica. The treated silica, if added to the liquid product, serves as agent to heighten the viscosity, prevent the sedimentation and disperse the particles. The highest effect is given to heighten the viscosity in a region of 4 to 9 in pH in water and alcohol. As filling agent to strengthen the elastomer and polymer, and powder product, it gives an effect to prevent the consolidation and improve the fluidity. As for its other applications, utilization is made of particulate superfineness, high purity, thermal insulation properties and adsorption characteristics. 2 to 3 patents are published for it as raw material of quartz glass. 38 refs., 16 figs., 4 tabs.

Effect of antimicrobial agents on cellulose acetate nano composites properties

Energy Technology Data Exchange (ETDEWEB)

Rodriguez, Francisco J.; Bruna, Julio E.; Galotto, Maria J.; Guarda, Abel; Sepulveda, Hugo, E-mail: francisco.rodriguez.m@usach.cl [Center for the Development of Nanoscience and Nanotechnology (CEDENNA). Universidad de Santiago de Chile. Faculty of Technology. Department of Food Science and Technology. Food Packaging Laboratory. Santiago (Chile)

2011-07-01

Nano composites based on cellulose acetate, Cloisite 30B, triethyl citrate and thymol or cinnamaldehyde were prepared using a dissolution casting technique. The effect of thymol and cinnamaldehyde on the cellulose acetate nano composite properties was evaluated by XRD and DSC. Important changes on the thermal properties and morphological structure were observed according to thymol and cinnamaldehyde content. (author)

Effect of antimicrobial agents on cellulose acetate nano composites properties

International Nuclear Information System (INIS)

Rodriguez, Francisco J.; Bruna, Julio E.; Galotto, Maria J.; Guarda, Abel; Sepulveda, Hugo

2011-01-01

Nano composites based on cellulose acetate, Cloisite 30B, triethyl citrate and thymol or cinnamaldehyde were prepared using a dissolution casting technique. The effect of thymol and cinnamaldehyde on the cellulose acetate nano composite properties was evaluated by XRD and DSC. Important changes on the thermal properties and morphological structure were observed according to thymol and cinnamaldehyde content. (author)

Effects of roughness on interfacial performances of silica glass and non-polar polyarylacetylene resin composites

International Nuclear Information System (INIS)

Jiang, Z.X.; Huang, Y.D.; Liu, L.; Long, J.

2007-01-01

The influence of roughness on interfacial performances of silica glass/polyarylacetylene resin composites was investigated. In order to obtain different roughness, silica glass surface was abraded by different grits of abrasives and its topography was observed by scanning electron microscopy and atomic force microscopy. At the same time, the failure mechanisms of composites were analyzed by fracture morphologies and the interfacial adhesion was evaluated by shear strength test. The results indicated that shear strength of silica glass/polyarylacetylene resin composites firstly increased and then decreased with the surface roughness of silica glass increased. The best surface roughness range of silica glass was 40-60 nm. The main mechanism for the improvement of the interfacial adhesion was physical interlocking at the interface

Synthesis of nano-textured biocompatible scaffolds from chicken eggshells

International Nuclear Information System (INIS)

Asghar, Waseem; Ilyas, Azhar; Sankaran, Jeyantt; Wan Yuan; Iqbal, Samir M; Kim, Young-Tae

2012-01-01

Cell adhesion, morphology and growth are influenced by surface topography at nano and micrometer scales. Nano-textured surfaces are prepared using photolithography, plasma etching and long polymer chemical etching which are cost prohibitive and require specialized equipment. This article demonstrates a simple approach to synthesize nano-textured scaffolds from chicken eggshells. Varieties of pattern are made on the eggshells like micro-needle forests and nanopores, giving very uniform nano-textures to the surfaces. The surfaces are characterized for chemical composition and crystal phase. The novel patterns are transferred to PDMS surfaces and the nano-textured PDMS surfaces are used to study the effect of texturing on human fibroblast cell growth and attachment. The effects of surface topographies, along with laminin coating on cell cultures, are also studied. We find an exciting phenomenon that the initial seeding density of the fibroblast cells affects the influence of the nano-texturing on cell growth. These nano-textured surfaces give 16 times more fibroblast growth when compared to flat PDMS surfaces. The novel nano-textured patterns also double the laminin adsorption on PDMS. (paper)

Nano-structural characteristics and optical properties of silver chiral nano-flower sculptured thin films

Energy Technology Data Exchange (ETDEWEB)

Savaloni, Hadi, E-mail: savaloni@khayam.ut.ac.ir [Department of Physics, University of Tehran, North-Kargar Street, Tehran (Iran, Islamic Republic of); Haydari-Nasab, Fatemh; Malmir, Mariam [Department of Physics, University of Tehran, North-Kargar Street, Tehran (Iran, Islamic Republic of)

2011-08-15

Silver chiral nano-flowers with 3-, 4- and 5-fold symmetry were produced using oblique angle deposition method in conjunction with the rotation of sample holder with different speeds at different sectors of each revolution corresponding to symmetry order of the acquired nano-flower. Atomic force microscopy (AFM) and field emission scanning electron microscopy (FESEM), were employed to obtain morphology and nano-structure of the films. Optical characteristics of silver chiral nano-flower thin films were obtained using single beam spectrophotometer with both s- and p-polarization incident light at 30{sup o} and 70{sup o} incidence angles and at different azimuthal angles ({phi}). Optical spectra showed both TM (TDM (transverse dipole mode) and TQM (transverse quadruple mode)) and LM (longitudinal mode) Plasmon resonance peaks. For 3- and 4-fold symmetry chiral nano-flowers the s-polarization extinction spectra obtained at different azimuthal angles did not show significant change in the Plasmon peak position while 5-fold symmetry chiral nano-flower showed a completely different behavior, which may be the result of increased surface anisotropy, so when the {phi} angle is changed the s-polarization response from the surface can change more significantly than that for lower symmetries. In general, for 3-, 4- and 5-fold symmetry chiral nano-flowers a sharp peak at lower wavelengths (<450 nm) is observed in the s-polarization spectra, while in addition to this peak a broad peak at longer wavelengths (i.e., LM) observed in the p-polarization spectra, which is more dominant for 70{sup o} incidence angle.

Magnetic silica hybrids modified with guanidine containing co-polymers for drug delivery applications

Energy Technology Data Exchange (ETDEWEB)

Timin, Alexander S., E-mail: a_timin@mail.ru [Inorganic Chemistry Department, Ivanovo State University of Chemistry and Technology (ISUCT), 7, Sheremetevsky prosp., 153000 Ivanovo (Russian Federation); RASA Center in Tomsk, Tomsk Polytechnic University, 30, Lenin Avenue, 634500 Tomsk (Russian Federation); Khashirova, Svetlana Yu. [Kabardino-Balkar State University, ul. Chernyshevskogo 173, Nal' chik, 360004 Kabardino-Balkaria (Russian Federation); Rumyantsev, Evgeniy V.; Goncharenko, Alexander A. [Inorganic Chemistry Department, Ivanovo State University of Chemistry and Technology (ISUCT), 7, Sheremetevsky prosp., 153000 Ivanovo (Russian Federation)

2016-07-01

Guanidine containing co-polymers grafted onto silica nanoparticles to form core-shell structure were prepared by sol-gel method in the presence of γ-Fe{sub 2}O{sub 3} nanoparticles. The morphological features for uncoated and coated silica particles have been characterized with scanning electron microscopy. The results show that the polymer coated silicas exhibit spherical morphology with rough polymeric surface covered by γ-Fe{sub 2}O{sub 3} nanoparticles. The grafting amount of guanidine containing co-polymers evaluated by thermogravimetric analysis was in the range from 17 to 30%. Then, the drug loading properties and cumulative release of silica hybrids modified with guanidine containing co-polymers were evaluated using molsidomine as a model drug. It was shown that after polymer grafting the loading content of molsidomine could reach up to 3.42 ± 0.21 and 2.34 ± 0.14 mg/g respectively. The maximum drug release of molsidomine is achieved at pH 1.6 (approximately 71–75% release at 37 °C), whereas at pH 7.4 drug release is lower (50.4–59.6% release at 37 °C). These results have an important implication that our magneto-controlled silica hybrids modified with guanidine containing co-polymers are promising as drug carriers with controlled behaviour under influence of magnetic field. - Highlights: • Polymer coated silica hybrids containing γ-Fe{sub 2}O{sub 3} were prepared via sol–gel method. • Polymer grafting influences pH-response and surface properties of final products. • Molsidomine as a model drug was effectively loaded into polymer coated silicas. • The drug loading depends on the nature of grafted polymer and its content.

Polymer-Silica Nanocomposites: A Versatile Platform for Multifunctional Materials

Science.gov (United States)

Chiu, Chi-Kai

Solution sol-gel synthesis is a versatile approach to create polymer-silica nanocomposite materials. The solution-to-solid transformation results in a solid consisting of interconnected nanoporous structure in 3D space, making it the ideal material for filtration, encapsulation, optics, electronics, drug release, and biomaterials, etc. Although the pore between nano and meso size may be tunable using different reaction conditions, the intrinsic properties such as limited diffusion within pore structure, complicated interfacial interactions at the pore surfaces, shrinkage and stress-induced cracking and brittleness have limited the applications of this material. To overcome these problems, diffusion, pore size, shrinkage and stress-induced defects need further investigation. Thus, the presented thesis will address these important questions such as whether these limitations can be utilized as the novel method to create new materials and lead to new applications. First, the behaviors of polymers such as poly(ethylene glycol) inside the silica pores are examined by studying the nucleation and growth of AgCl at the surface of the porous matrix. The pore structure and the pressure induced by the shrinkage affect have been found to induce the growth of AgCl nanocrystals. When the same process is carried out at 160 °C, silver metallization is possible. Due to the shrinkage-induced stresses, the polymer tends to move into open crack spaces and exterior surfaces, forming interconnected silver structure. This interconnected silver structure is very unique because its density is not related to the size scale of nanopore structures. These findings suggest that it is possible to utilize defect surface of silica material as the template to create interconnected silver structure. When the scale is small, polymer may no longer be needed if the diffusion length of Ag is more than the size of silica particles. To validate our assumption, monoliths of sol-gel sample containing AgNO3

Semi-flexible polymer engendered aggregation/dispersion of fullerene (C60) nano-particles: An atomistic investigation

Science.gov (United States)

Kumar, Sunil; Pattanayek, Sudip K.

2018-06-01

Semi flexible polymer chain has been modeled by choosing various values of persistent length (stiffness). As the polymer chain stiffness increases, the shape of polymer chain changes from globule to extended cigar to toroid like structure during cooling from a high temperature. The aggregation of fullerene nano-particles is found to depend on the morphology of polymer chain. To maximize, the number of polymer bead-nanoparticle contacts, all nano-particle have positioned inside the polymer globule. To minimize, the energy penalty, due to bending of the polymer chain, all nano-particle have positioned on the surface of the polymer's cigar and toroid morphology.

Synthesis of multilayered structure of nano-dimensional silica glass/reduced graphene oxide for advanced electrochemical applications.

Science.gov (United States)

Ghosh, Arnab; Miah, Milon; Majumder, Chinmoy; Bag, Shekhar; Chakravorty, Dipankar; Saha, Shyamal Kumar

2018-03-28

During the past few years, intensive research has been carried out to design new functional materials for superior electrochemical applications. Due to low storage capacity and low charge transport, silica based glasses have not yet been investigated for their supercapacitive behavior. Therefore, in the present study, a multilayered structure of silica-based nanoglass and reduced graphene oxide has been designed to remarkably enhance the specific capacitance by exploiting the porosity, large surface area, sufficient dangling bonds in the nanoglass and high electrical conductivity of rGO. The charge transport in the composite structure is also investigated to understand the electrochemical properties. It is found that Simmons tunneling or direct tunneling is the dominant mechanism of charge conduction between the graphene layers via the potential barrier of silica nanoglass phase. We believe that this study will open up a new area in the design of glass-based two-dimensional nanocomposites for superior supercapacitor applications.

Amorphous silica maturation in chemically weathered clastic sediments

Science.gov (United States)

Liesegang, Moritz; Milke, Ralf; Berthold, Christoph

2018-03-01

A detailed understanding of silica postdepositional transformation mechanisms is fundamental for its use as a palaeobiologic and palaeoenvironmental archive. Amorphous silica (opal-A) is an important biomineral, an alteration product of silicate rocks on the surface of Earth and Mars, and a precursor material for stable silica phases. During diagenesis, amorphous silica gradually and gradationally transforms to opal-CT, opal-C, and eventually quartz. Here we demonstrate the early-stage maturation of several million year old opal-A from deeply weathered Early Cretaceous and Ordovician sedimentary rocks of the Great Artesian Basin (central Australia). X-ray diffraction, scanning electron microscopy, and electron probe microanalyses show that the mineralogical maturation of the nanosphere material is decoupled from its chemical properties and begins significantly earlier than micromorphology suggests. Non-destructive and locally highly resolved X-ray microdiffraction (μ-XRD2) reveals an almost linear positive correlation between the main peak position (3.97 to 4.06 Å) and a new asymmetry parameter, AP. Heating experiments and calculated diffractograms indicate that nucleation and growth of tridymite-rich nanodomains induce systematic peak shifts and symmetry variations in diffraction patterns of morphologically juvenile opal-A. Our results show that the asymmetry parameter traces the early-stage maturation of amorphous silica, and that the mineralogical opal-A/CT stage extends to smaller d-spacings and larger FWHM values than previously suggested.

Time-response relationship of nano and micro particle induced lung inflammation. Quartz as reference compound

DEFF Research Database (Denmark)

Roursgaard, Martin; Poulsen, Steen Seier; Poulsen, Lars K.

2010-01-01

-response profiles of nano- and micro-sized particles. The potency of the two samples cannot be compared; during the milling process, a substantial part of the quartz was converted to amorphous silica and contaminated with corundum. For screening, BALF PMN, either TNF-a or IL-1ß at 16 hours post instillation may...

Hydrodeoxygenation of fatty acid esters catalyzed by Ni on nano-sized MFI type zeolites

Energy Technology Data Exchange (ETDEWEB)

Schreiber, Moritz W.; Rodriguez-Niño, Daniella; Gutiérrez, Oliver Y.; Lercher, Johannes A.

2016-01-01

The impact of support morphology and composition on the intrinsic activity of Ni supported on MFI-type zeolite was explored in the hydrodeoxygenation of methyl stearate, tristearate, and algae oil (mixture of triglycerides). The nano-sized structure of the support (self-pillared nanosheets) is beneficial for the activity of the catalysts. Higher Ni dispersion and concomitant higher reaction rates were obtained on nano-structured supports than on zeolite with conventional morphology. Rates normalized to accessible Ni atoms (TOF), however, varied little with support morphology. Acidity of the support increases the rate of Ni-catalyzed C-O hydrogenolysis per surface metal site.

Hydrothermal synthesis of meso porous silica MCM-41 using commercial sodium silicate

Energy Technology Data Exchange (ETDEWEB)

Melendez O, H. I.; Mercado S, A.; Garcia C, L. A.; Castruita, G.; Perera M, Y A., E-mail: ivan_melendez380@hotmail.com [Centro de Investigacion en Quimica Aplicada, Bldv. Enrique Reyna Hermosillo No. 140, Saltillo 25294, Coahuila (Mexico)

2013-08-01

In this work, ordered meso porous silica MCM-41 was prepared by hydrothermal synthesis using industrial-grade sodium silicate (Na{sub 2}SiO{sub 3}) as silica source, hexadecyltrimethyl-ammonium bromide (CTAB) as template agent and ethyl acetate as ph regulator. The influence of CTAB/SiO{sub 2} molar ratio, reaction time, aging temperature, and co-surfactant type on the structural and morphological properties of the obtained silica was studied. The products were characterized by X-ray diffraction, scanning electron microscopy, transmission electron microscopy and nitrogen adsorption-desorption isotherms. Ordered meso porous MCM-41 silica was obtained at 80 C by using a range of CTAB/SiO{sub 2} molar ratio from 0.35 to 0.71 and reaction times up to 72 h and isopropanol (i-Pr OH) as co-surfactant. (Author)

Morphology and properties of silica/novolac hybrid xerogels synthesized using sol–gel polymerization at solvent vapor-saturated atmosphere

International Nuclear Information System (INIS)

Seraji, Mohamad Mehdi; Seifi, Azadeh; Bahramian, Ahmad Reza

2015-01-01

Highlights: • Sol–gel polymerization in vapor of solvent saturated atmosphere is developed. • Highly porous novolac–silica hybrid xerogels are successfully synthesized. • Novolac–silica hybrid gel was dried in ambient condition with low shrinkage. • Required time for preparation of gel reduced from 5 days to about 5 h. • By incorporation of silica into the novolac xerogel structure, the pore size decreases. - Abstract: Highly porous novolac–silica hybrid xerogels were successfully synthesized via the novel method of sol–gel polymerization in solvent vapor-saturated atmosphere. This method removes the need for supercritical drying and yields the hybrid xerogels with reduced shrinkage in comparison with conventional sol–gel process. Tetraethoxysilane (TEOS) was used as the precursor of silica-based inorganic phase. The chemical and structural characterization of the prepared hybrid xerogels were performed by Fourier transform infrared spectroscopy (FTIR) and scanning electron microscopy (SEM) analysis, respectively. Thermal and mechanical properties of the hybrid samples were investigated by differential scanning calorimetry (DSC), and compressive strength analysis. The resultant hybrid xerogels show a nanostructured colloidal hybrid network with high porosity (above 80%) and low density (below 0.25 g cm −3 ). Si mapping images shows the good distribution of silica phase throughout the hybrid structure

Organization of research team for nano-associated safety assessment in effort to study nanotoxicology of zinc oxide and silica nanoparticles

Directory of Open Access Journals (Sweden)

Kim YR

2014-12-01

Full Text Available Yu-Ri Kim,1,* Sung Ha Park,2,* Jong-Kwon Lee,3 Jayoung Jeong,3 Ja Hei Kim,4 Eun-Ho Meang,5 Tae Hyun Yoon,6 Seok Tae Lim,7 Jae-Min Oh,8 Seong Soo A An,9 Meyoung-Kon Kim1 1Department of Biochemistry and Molecular Biology, Korea University Medical School and College, Seoul, South Korea; 2Department of Biochemistry, University of Bath, Bath, UK; 3Toxicological Research Division, National Institute of Food and Drug Safety Evaluation, Chungchungbuk-do, 4Consumers Korea, Chongro-ku, 5General toxicology team, Korea Testing and Research Institute, 6Laboratory of Nanoscale Characterization and Environmental Chemistry, Department of Chemistry, College of Natural Sciences, Hanyang University, Seoul, 7Department of Nuclear Medicine, Chonbuk National University Medical School, Jeonju, Jellabuk-Do, 8Department of Chemistry and Medical Chemistry, College of Science and Technology, Yonsei University, Gangwon-do, 9Department of Bionanotechnology, Gachon Medical Research Institute, Gachon University, Seongnam, South Korea *Authors contributed equally to this work Abstract: Currently, products made with nanomaterials are used widely, especially in biology, biotechnologies, and medical areas. However, limited investigations on potential toxicities of nanomaterials are available. Hence, diverse and systemic toxicological data with new methods for nanomaterials are needed. In order to investigate the nanotoxicology of nanoparticles (NPs, the Research Team for Nano-Associated Safety Assessment (RT-NASA was organized in three parts and launched. Each part focused on different contents of research directions: investigators in part I were responsible for the efficient management and international cooperation on nano-safety studies; investigators in part II performed the toxicity evaluations on target organs such as assessment of genotoxicity, immunotoxicity, or skin penetration; and investigators in part III evaluated the toxicokinetics of NPs with newly developed

Design of Cobalt Nanoparticles with Tailored Structural and Morphological Properties via O/W and W/O Microemulsions and Their Deposition onto Silica

Directory of Open Access Journals (Sweden)

Gabriella Di Carlo

2015-03-01

Full Text Available Cobalt nanostructures with different size and morphology, i.e., spherical nanoparticles, nanorods, and particles arranged into elongated structures, were prepared using micelles and microemulsions as confined reaction media. The syntheses were carried out using three types of systems: aqueous surfactant solutions, oil-in water (O/W, and water-in-oil (W/O microemulsions. The influence of the surfactant and the precipitating agent used for synthesis was also investigated. For this purpose, cobalt nanostructures were prepared using different non-ionic surfactants, namely Synperonic® 10/6, Pluronic® P123 and a mixture of SPAN 20–TWEEN 80. Three different precipitating agents were used: sodium borohydride, sodium hydroxide, and oxalic acid. Our findings revealed that by changing the type of reaction media as well as the precipitating agent it is possible to modify the shape and size of the cobalt nanostructures. Moreover, the use of O/W microemulsion generates better results in terms of colloidal stability and uniformity of particle size with respect to W/O microemulsion. The different cobalt nanostructures were supported on commercial and mesoporous silica; transmission electron microscopy (TEM images showed that after deposition the Co nanocrystals remain well dispersed on the silica supports. This behavior suggests their great potential in catalytic applications.

Nano-sized Li4Ti5O12 anode material with excellent performance prepared by solid state reaction: The effect of precursor size and morphology

International Nuclear Information System (INIS)

Li, Xiangru; Hu, Hao; Huang, Sheng; Yu, Gaige; Gao, Lin; Liu, Haowen; Yu, Ying

2013-01-01

Graphical abstract: - Highlights: • Nano-sized Li 4 Ti 5 O 12 has been prepared through solid state reaction by using axiolitic TiO 2 as precursor. • The prepared nano-sized Li 4 Ti 5 O 12 anode material shows excellent electrochemical performance. • The utilization of precursor with special morphology and size is one of the useful ways to prepare more active electrode materials. - Abstract: Spinel nano-sized Li 4 Ti 5 O 12 anode material of secondary lithium-ion battery has been successfully prepared by solid state reaction using axiolitic TiO 2 assembled by 10–20 nm nanoparticles and Li 2 CO 3 as precursors. The synthesis condition, grain size effect and corresponding electrochemical performance of the special Li 4 Ti 5 O 12 have been studied in comparison with those of the normal Li 4 Ti 5 O 12 originated from commercial TiO 2 . We also propose the mechanism that using the nano-scaled TiO 2 with special structure and unexcess Li 2 CO 3 as precursors can synthesize pure phase nano-sized Li 4 Ti 5 O 12 at 800 °C through solid state reaction. The prepared nano-sized Li 4 Ti 5 O 12 anode material for Li-ion batteries shows excellent capacity performance with rate capacity of 174.2, 164.0, 157.4, 146.4 and 129.6 mA h g −1 at 0.5, 1, 2, 5 and 10 C, respectively, and capacity retention of 95.1% after 100 cycles at 1 C. In addition, the specific capacity fade for the cell with the different Li 4 Ti 5 O 12 active materials resulted from the increase of internal resistance after 100 cycles is compared

Tough ceramic coatings: Carbon nanotube reinforced silica sol-gel

Science.gov (United States)

López, A. J.; Rico, A.; Rodríguez, J.; Rams, J.

2010-08-01

Silica coatings reinforced with carbon nanotubes were produced via sol-gel route using two mixing techniques of the sol-gel precursors, mechanical and ultrasonic mixing, and dip-coating as deposition process on magnesium alloy substrates. Effective incorporation and distribution of 0.1 wt.% of carbon nanotubes in the amorphous silica matrix of the coatings were achieved using both techniques. Fabrication procedure determines the morphological aspects of the coating. Only mechanical mixing process produced coatings dense and free of defects. Nanoindentation technique was used to examine the influence of the fabrication process in the mechanical features of the final coatings, i.e. indentation fracture toughness, Young's modulus and hardness. A maximum toughening effect of about 24% was achieved in silica coatings reinforced with carbon nanotubes produced by the mechanical mixing route. Scanning electron microscopy investigation revealed that the toughening of these reinforced coatings was mainly due to bridging effect of the reinforcement.

Nitridated fibrous silica (KCC-1) as a sustainable solid base nanocatalyst

KAUST Repository

Bouhrara, Mohamed; Ranga, Chanakya; Fihri, Aziz; Shaikh, Rafik; Sarawade, Pradip; Emwas, Abdul-Hamid M.; Hedhili, Mohamed N.; Polshettiwar, Vivek

2013-01-01

We observed that support morphology has dramatic effects on the performance of nitridated silica as a base. By simply replacing conventional silica supports (such as SBA-15 and MCM-41) with fibrous nanosilica (KCC-1), we observed multifold enhancement in the catalytic activity of the nitridated solid base for Knoevenagel condensations and transesterification reactions. This enhancement of the activity can be explained by amine accessibility, which is excellent in KCC-1 due to its open and flexible fibrous structure, that facilitates penetration and interaction with basic amine sites. © 2013 American Chemical Society.

Nitridated fibrous silica (KCC-1) as a sustainable solid base nanocatalyst

KAUST Repository

Bouhrara, Mohamed

2013-09-03

We observed that support morphology has dramatic effects on the performance of nitridated silica as a base. By simply replacing conventional silica supports (such as SBA-15 and MCM-41) with fibrous nanosilica (KCC-1), we observed multifold enhancement in the catalytic activity of the nitridated solid base for Knoevenagel condensations and transesterification reactions. This enhancement of the activity can be explained by amine accessibility, which is excellent in KCC-1 due to its open and flexible fibrous structure, that facilitates penetration and interaction with basic amine sites. © 2013 American Chemical Society.

Characterization of Electret Based on Inorganic-organic Nanocomposite Using Fluoropolymer and Silica Nanoparticles

International Nuclear Information System (INIS)

Suzuki, M; Shimokizaki, M; Takahashi, T; Aoyagi, S; Yoshikawa, Y

2015-01-01

An A novel electret based on inorganic-organic nano composite using fluoropolymer and silica nanoparticles was developed in this study. CYTOP® is used to fabricate the nanocomposite electret, which is one of fluoropolymer. Three kinds of silica nanoparticles dispersed in methyl ethyl ketone were employed. Each type of nanoparticles was mixed in the CYTOP or stuck between three layers of CYTOP. Then, negative charge was implanted by corona discharge method. The initial surface potential of the nanocomposite electret was higher than that of a control electret made of pure CYTOP. Additionally, time stability of those was also better than that of control electret. However, above mentioned properties of the mix-typed electret was worse than that of stuck-typed electret, because of discharging through aggregates composed of the nanoparticles. (paper)

PREFACE: International Conference on Structural Nano Composites (NANOSTRUC 2012)

Science.gov (United States)

Njuguna, James

2012-09-01

Dear Colleagues It is a great pleasure to welcome you to NanoStruc2012 at Cranfield University. The purpose of the 2012 International Conference on Structural Nano Composites (NanoStruc2012) is to promote activities in various areas of materials and structures by providing a forum for exchange of ideas, presentation of technical achievements and discussion of future directions. NanoStruc brings together an international community of experts to discuss the state-of-the-art, new research results, perspectives of future developments, and innovative applications relevant to structural materials, engineering structures, nanocomposites, modelling and simulations, and their related application areas. The conference is split in 7 panel sessions, Metallic Nanocomposites and Coatings, Silica based Nanocomposites, safty of Nanomaterials, Carboin based Nanocomposites, Multscale Modelling, Bio materials and Application of Nanomaterials. All accepted Papers will be published in the IOP Conference Series: Materials Science and Engineering (MSE), and included in the NanoStruc online digital library. The abstracts will be indexed in Scopus, Compedex, Inspec, INIS (International Nuclear Information System), Chemical Abstracts, NASA Astrophysics Data System and Polymer Library. Before ending this message, I would like to acknowledge the hard work, professional skills and efficiency of the team which ensured the general organisation. As a conclusion, I would like to Welcome you to the Nanostruc2012 and wish you a stimulating Conference and a wonderful time. On behalf of the scientific committee, Signature James Njuguna Conference Chair The PDF of this preface also contains committee listings and associates logos.

Diversity in the Archean Biosphere: New Insights from NanoSIMS

Science.gov (United States)

Oehler, Dorothy Z.; Robert, François; Walter, Malcolm R.; Sugitani, Kenichiro; Meibom, Anders; Mostefaoui, Smail; Gibson, Everett K.

2010-05-01

The origin of organic microstructures in the ˜3 Ga Farrel Quartzite is controversial due to their relatively poor state of preservation, the Archean age of the cherts in which they occur, and the unusual spindle-like morphology of some of the forms. To provide more insight into the significance of these microstructures, nano-scale secondary ion mass spectrometry (NanoSIMS) maps of carbon, nitrogen, sulfur, silicon, and oxygen were obtained for spheroidal and spindle-shaped constituents of the Farrel Quartzite assemblage. Results suggest that the structures are all bona fide ˜3 Ga microfossils. The spindles demonstrate an architecture that is remarkable for 3 Ga organisms. They are relatively large, robust, and morphologically complex. The NanoSIMS element maps corroborate their complexity by demonstrating an intricate, internal network of organic material that fills many of the spindles and extends continuously from the body of these structures into their spearlike appendages. Results from this study combine with previous morphological and chemical analyses to argue that the microstructures in the Farrel Quartzite comprise a diverse assemblage of Archean microfossils. This conclusion adds to a growing body of geochemical, stromatolitic, and morphological evidence that indicates the Archean biosphere was varied and well established by at least ˜3 Ga. Together, the data paint a picture of Archean evolution that is one of early development of morphological and chemical complexity. The evidence for Archean evolutionary innovation may augur well for the possibility that primitive life on other planets could adapt to adverse conditions by ready development of diversity in form and biochemistry.

Giant basal spicule from the deep-sea glass sponge Monorhaphis chuni: synthesis of the largest bio-silica structure on Earth by silicatein

Science.gov (United States)

Wang, Xiao-hong; Zhang, Xue-hua; Schröder, Heinz C.; Müller, Werner E. G.

2009-09-01

Like all sponges (phylum Porifera), the glass sponges (Hexactinellida) are provided with an elaborate and distinct body plan, which relies on a filigree skeleton. It is constructed by an array of morphologically determined elements, the spicules. Schulze described the largest siliceous hexactinellid sponge on Earth, the up to 3 m high Monorhaphis chuni, collected during the German Deep Sea Expedition "Valdivia" (1898-1899). This species develops an equally large bio-silica structure, the giant basal spicule (3 m × 10 mm). Using these spicules as a model, one can obtain the basic knowledge on the morphology, formation, and development of silica skeletal elements. The silica matrix is composed of almost pure silica, endowing it with unusual optophysical properties, which are superior to those of man-made waveguides. Experiments suggest that the spicules function in vivo as a nonocular photoreception system. The spicules are also provided with exceptional mechanical properties. Like demosponges, the hexactinellids synthesize their silica enzymatically via the enzyme silicatein (27 kDa protein). This enzyme is located in/embedded in the silica layers. This knowledge will surely contribute to a further utilization and exploration of silica in biomaterial/biomedical science.

Characteristics of Sodium Polyacrylate/Nano-Sized Carbon Hydrogel for Biomedical Patch.

Science.gov (United States)

Park, Jong-Kyu; Seo, Sun-Kyo; Cho, Seungkwan; Kim, Han-Sung; Lee, Chi-Hwan

2018-03-01

Conductive hydrogels were prepared for biomedical patch in order to improve the electrical conductivity. Sodium polyacrylate and nano-sized carbon were mixed and fabricated by aqueous solution gelation process in various contents of nano-sized carbon with 0.1, 0.5, 1.0 and 2.0 wt%. Sodium polyacrylate/nano-sized carbon conductive hydrogels were investigated by molecular structure, surface morphology and electrical conductivity. The conductivity of the hydrogel/nano-sized carbon conductive hydrogel proved to be 10% higher than conductive hydrogel without nano-sized carbon. However, it was founded that conductive hydrogels with nano-sized carbon content from 0.5 up to 2.0 wt% were remarkably decreased. This may be due to the non-uniform distribution of nano-sized carbon, resulting from agglomerates of nano-sized carbon. The developed hydrogel is intended for use in the medical and cosmetic fields that is applicable to supply micro-current from device to human body.

Structural and luminescence properties of europium(III)-doped zirconium carbonates and silica-supported Eu3+-doped zirconium carbonate nanoparticles

International Nuclear Information System (INIS)

Sivestrini, S.; Riello, P.; Freris, I.; Cristofori, D.; Enrichi, F.; Benedetti, A.

2010-01-01

The synthesis, morphology and luminescence properties of europium(III)-doped zirconium carbonates prepared as bulk materials and as silica-supported nanoparticles with differing calcination treatments are reported. Transmission electron microscopy and X-ray diffraction analyses have, respectively, been used to study the morphology and to quantify the atomic amount of europium present in the optically active phases of the variously prepared nanomaterials. Rietveld analysis was used to quantify the constituting phases and to determinate the europium content. Silica particles with an approximate size of 30 nm were coated with 2 nm carbonate nanoparticles, prepared in situ on the surface of the silica core. Luminescence measurements revealed the role of different preparation methods and of europium-doping quantities on the optical properties observed.

Structural Characterization of Silica Particles Extracted from Grass Stenotaphrum secundatum: Biotransformation via Annelids

Directory of Open Access Journals (Sweden)

A. Espíndola-Gonzalez

2014-01-01

Full Text Available This study shows the structural characterization of silica particles extracted from Stenotaphrum secundatum (St. Augustine grass using an annelid-based biotransformation process. This bioprocess starts when St. Augustine grass is turned into humus by vermicompost, and then goes through calcination and acid treatment to obtain silica particles. To determine the effect of the bioprocess, silica particles without biotransformation were extracted directly from the sample of grass. The characterization of the silica particles was performed using Infrared (FTIR and Raman spectroscopy, Transmission Electron Microscopy (TEM, X-ray Diffraction (XRD, Dynamic Light Scattering (DLS, and Energy Dispersion Spectroscopy (EDS. Both types of particles showed differences in morphology and size. The particles without biotransformation were essentially amorphous while those obtained via annelids showed specific crystalline phases. The biological relationship between the metabolisms of worms and microorganisms and the organic-mineral matter causes changes to the particles' properties. The results of this study are important because they will allow synthesis of silica in cheaper and more ecofriendly ways.

Synthesis of PANi-SiO2 Nanocomposite with In-Situ Polymerization Method: Nanoparticle Silica (NPS) Amorphous and Crystalline Phase

Science.gov (United States)

Munasir; Luvita, N. R. D.; Kusumawati, D. H.; Putri, N. P.; Triwikantoro; Supardi, Z. A. I.

2018-03-01

Silica which is synthesized from natural materials such as Bancar Tuban’s sand composited with Polyaniline (PANi), where the silica used are silica has an amorphous phase and cristobalite phase. In this research, the composite method used is in- situ polymerization, which is silica entered during the fabrication of PANi, then automatically silica will be substitute into the chain bonding of PANi. The aim of this research is to find out the results of a composite process using in-situ methods as well as differences in the morphology of PANi/a- SiO2 and PANi/c-SiO2. For the characterization of samples tested in the form of FTIR to determine the functional groups of the composite and SEM to determine the morphology of the sample. From the test results of FTIR are known composite possibility has occurred because there are several functional groups belonging to silica also functional groups belonging polyaniline, functional group that’s happened in wave numbers were almost identical between PANi/a-SiO2 and PANi/c-SiO2, but there are little differences were seen in the form of a graph generated from the peak and intensity that occurred charts for PANi/c-SiO2 has peak more pointed or sharp compared to PANi/a-SiO2 because that bond of crystal is strong, stiff and has a larger particle size than the amorphous composite. Then from the data of SEM seen clearly their morphological differences between PANi/a-SiO2 and PANi/c-SiO2 where polyaniline is composited with amorphous silica will have a fault that is not uniform or irregular different from PANi/c -SiO2 has a regular fault and this is corresponding with the nature of the typical structure of amorphous and crystalline.

Study on Carbon Nano composite Counter electrode for Dye-Sensitized Solar Cells

International Nuclear Information System (INIS)

Chen, Y.; Zhang, H.; Lin, J.

2012-01-01

Carbon nano composite electrodes were prepared by adding carbon nano tubes (CNTs) into carbon black as counter electrodes of dye-sensitized solar cells (DSSCs). The morphology and structure of carbon nano composite electrodes were studied by scanning electron microscopy. The influence of CNTs on the electrochemical performance of carbon nano composite electrodes is investigated by cyclic voltammetry and electrochemical impedance spectroscopy. Carbon nano composite electrodes with CNTs exhibit a highly interconnected network structure with high electrical conductivity and good catalytic activity. The influence of different CNTs content in carbon nano composite electrodes on the open-circuit voltage, short-circuit current, and filling factor of DSSCs is also investigated. DSSCs with 10% CNTs content exhibit the best photovoltaic performance in our experiments.

Some Observations on Carbon Nano tubes Susceptibility to Cell Phagocytosis

International Nuclear Information System (INIS)

Fraczek-Szczypta, A.; Menaszek, E.; Blazewicz, S.; Menaszek, E.

2011-01-01

The aim of this study was to assess the influence of different types of carbon nano tubes (CNTs) on cell phagocytosis. Three kinds of carbon nano tubes: single-walled carbon nano horns (SWCNHs), multi walled carbon nano tubes (MWCNTs), and ultra-long single-walled carbon nano tubes (ULSWCNTs) before and after additional chemical functionalization were seeded with macrophage cell culture. Prior to biological testing, the CNTs were subjected to dispersion process with the use of phosphate buffered solution (PBS) and PBS containing surfactant (Tween 20) or dimethyl sulfoxide (DMSO). The results indicate that the cells interaction with an individual nano tube is entirely different as compared to CNTs in the form of aggregate. The presence of the surfactant favors the CNTs dispersion in culture media and facilitates phagocytosis process, while it has disadvantageous influence on cells morphology. The cells phagocytosis is a more effective for MWCNTs and SWCNHs after their chemical functionalization. Moreover, these nano tubes were well dispersed in culture media without using DMSO or surfactant. The functionalized carbon nano tubes were easily dispersed in pure PBS and seeded with cells

Template-assisted growth of nano structured functional materials

International Nuclear Information System (INIS)

Ying, K.K.; Nur Ubaidah Saidin; Khuan, N.I.; Suhaila Hani Ilias; Foo, C.T.

2012-01-01

Template-assisted growth is an important nano electrochemical deposition technique for synthesizing one-dimensional (1-D) nano structures with uniformly well-controlled shapes and sizes. A good template with well-defined dimensions is imperative for realizing this task. Porous anodic alumina (PAA) has been a favorable candidate for this purpose as it can be tailor-made with precise pore geometries, such as pore length and diameter as well as inter-pore distances, via the anodization of pure aluminium. This paper reports the fabrication of PAA templates and electrochemical synthesis of functional nano structures in the form of nano wires using PAA templates as scaffolds. Axial heterostructure and homogeneous nano wires formed by engineering materials configuration via composition and/ or layer thickness variations were fabricated for different functionalities. X-ray diffraction and imaging techniques were used to alucidate the microstructures, morphologies and chemical compositions of the nano wires produced. Due to their large surface area-to-volume ratios, and therefore high sensitivities, these functional nano structures have useful applications as critical components in nano sensor devices and various areas of nano technology. Potential applications include as hydrogen gas sensors in nuclear power plant for monitoring structural integrity of reactor components and containment building, as well as environmental monitoring of air pollution and leakages of toxic gases and chemicals. (Author)

Zinc oxide hollow micro spheres and nano rods: Synthesis and applications in gas sensor

International Nuclear Information System (INIS)

Jamil, Saba; Janjua, Muhammad Ramzan Saeed Ashraf; Ahmad, Tauqeer; Mehmood, Tahir; Li, Songnan; Jing, Xiaoyan

2014-01-01

Zinc oxide nano rods and micro hollow spheres are successfully fabricated by adopting a simple solvo-thermal approach without employing any surfactant/template by keeping heating time as variable. The prepared products are characterized by using different instruments such as X-Ray Diffraction (XRD), Scanning Electron Microscopy (SEM) and Transmission Electron Microscopy (TEM). In order to investigate the morphological dependence on the reaction time, analogous experiments with various reaction times are carried out. Depending upon heating time, different morphological forms have been identified such as hollow microsphere (4 μm to 5 μm) and nano rods with an average diameter of approximately 100 nm. The fabricated materials are also tested for ethanol gas sensor applications and zinc oxide hollow microsphere proven to be an efficient gas sensing materials. Nitrogen adsorption–desorption measurement was performed to understand better performance of zinc oxide micro hollow spheres as effective ethanol gas sensing material. - Graphical abstract: Graphical abstract is represented by zinc oxide sphere (prepared by simple solvothermal approach), its XRD pattern(characterization) and finally its application in gas sensing. - Highlights: • Zinc oxide spheres were prepared by using solvothermal method. • Detailed description of the morphology of microspheres assembled by nano rods. • Formation mechanism of zinc oxide spheres assembled by nano rods. • Zinc oxide spheres and nano rods displayed very good gas sensing ability

A novel approach to fabrication of superparamagnetite hollow silica/magnetic composite spheres

Energy Technology Data Exchange (ETDEWEB)

Yuan Junjie, E-mail: yuanjunjie@tongji.edu.c [School of Materials Science and Engineering, Tongji University, Shanghai 200092 (China); Key Laboratory of Molecular Engineering of Polymers, Fudan University, Shanghai 200433 (China); Zhang Xiong; Qian He [School of Materials Science and Engineering, Tongji University, Shanghai 200092 (China)

2010-08-15

We described a method for synthesizing hollow silica/magnetic composite spheres using sulfonic acid functionalized hollow silica spheres (SAFHSS) as templates. The Fe{sub 3}O{sub 4} nanoparticles were deposited on or imbedded in the hollow silica shell by a precipitation reaction. The morphologies, composition and properties of the hollow composite spheres were characterized by transmission electron microscopy, Fourier transform infrared analysis, X-ray diffraction measurement and vibrating-sample magnetometry measurement. The results indicated crystal sizes and amount of the Fe{sub 3}O{sub 4} nanoparticles on the SAFHSS. The magnetic properties of the hollow composite spheres were controlled by adjusting the proportion between Fe{sup 2+} and Fe{sup 3+} and iron ion total concentration. When appropriate loading species were added into the system, superparamagnetite hollow composite spheres were obtained. The method also could be applicable to prepare other superparamagnetite hollow silica/ferrite composite spheres.

Effect of alkali ions (Na+, K+, Cs+) on reaction mechanism of CZTS nano-particles synthesis

Science.gov (United States)

Kumar, Suresh; Altosaar, Mare; Grossberg, Maarja; Mikli, Valdek

2018-04-01

The control of morphology, elemental composition and phase composition of Cu2ZnSnS4 (CZTS) nano-crystals depends on the control of complex formation and surface stabilization of nano-particles in solution-based synthesis in oleylamine. At temperatures ≥280 °C, the control of nano-crystal's morphology and homogenous growth is difficult because of fast poly-nuclear growth occurring at higher temperatures. In the present work the effect of oleylamine complex formation with different alkali ions (Na+, K+ and Cs+) on nano-crystals growth at synthesis temperature of 280 °C was studied. It was found that nano-powders synthesized in the presence of Na+ and K+ ions showed the formation of crystals of different sizes - small nano-particles (18 nm-30 nm), large aggregated crystals (few nm to 1 μm) and large single crystals (1 μm - 4 μm). The presence of Cs+ ions in the nano-powder synthesis in oleylamine-metal precursor-CsOH solution promoted growth of nano-crystals of homogenous size. It is proposed that the formed oleylamine-Cs complexes a) enhance the formation and stabilization of oleylamine-metal (Cu, Zn and Sn) complexes before the injection of sulphur precursor into the oleylamine-metal precursor solution and b) after addition of sulphur stabilize the fast nucleated nano-particles and promote diffusion limited growth.

Contribution to the study of the mechanism of crack in amorphous silica: study by the molecular dynamics of crack in amorphous silica

International Nuclear Information System (INIS)

Van Brutzel, L.

2000-01-01

The aim of this thesis was to understand the mechanism which occurs during the crack at the atomic scale in amorphous silica. The difficulties of the experimental observations at this length scale lead us to use numerical studies by molecular dynamics to access to the dynamical and the thermodynamical informations. We have carried out large simulations with 500000 atoms and studied the structure of the amorphous silica before to studying their behaviours under an imposed strain. The structure of this simulated amorphous silica settled in three length scales. In small length scale between 0 and 5 angstrom glass is composed of tetrahedra, this is close to the crystalline structure. In intermediate length scale between 3 and 10 angstrom tetrahedra are connected together and build rings of different sizes composed in majority between 5 and 7 tetrahedra. In bigger length scale between 15 and 60 angstrom, areas with high density of rings are surrounded by areas with low density of rings. These structural considerations play an important role in initiation and propagation of a crack. Indeed. in this length scale. crack propagates by growth and coalescence of some small cavities which appear in area with low density of rings behind the crack tip. The cavities dissipate the stress with carries away a delay to propagation of the crack. This phenomenons seems ductile and leads to non linear elastic behaviour near the crack tip. We have also shown that the addition of alkali in the amorphous silica changes the structure by creation of nano-porosities and leads to enhance the ductility during the crack propagation. (author)

Exploring encapsulation mechanism of DNA and mononucleotides in sol-gel derived silica.

Science.gov (United States)

Kapusuz, Derya; Durucan, Caner

2017-07-01

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