Shock-induced compaction of nanoparticle layers into nanostructured coating

NASA Astrophysics Data System (ADS)

Mayer, Alexander E.; Ebel, Andrei A.

2017-10-01

A new process of shock wave consolidation of nanoparticles into a nanocrystalline coating is theoretically considered. In the proposed scheme, the nanoparticle layers, which are attached to the substrate surface by adhesion, are compacted by plane ultra-short shock waves coming from the substrate. The initial adhesion is self-arisen at any contact between the nanoparticles without a pre-compression. The absence of the nanoparticle ejections due to the shock wave action is connected with the strong adhesive forces, which allow nanoparticles to be attached to each other and to substrate while they are being compacted; this should be valid for small enough nanoparticles. Severe plastic deformation of the nanoparticles and the increased temperature due to collapse of voids between them facilitate their compaction into the monolithic nanocrystalline layer. We consider the examples of Cu and Ni nanoparticles on Al substrate using molecular dynamic simulations. We show the efficiency of the action of multiple shock waves with the duration in the range 2-20 ps and the amplitude in the range 4-12 GPa for sequential layerwise compaction of nanoparticles. A series of shock waves can be created by a repetitive powerful pulsed laser irradiation of the opposite surface of the substrate. The method offers the challenge for the formation of nanostructured coatings of various compositions. The thickness of the compacted nanocrystalline coating can be locally varied and controlled by the number of acting pulses.

A plastic optical fiber sensor for the dual sensing of temperature and oxygen

NASA Astrophysics Data System (ADS)

Lo, Yu-Lung; Chu, Chen-Shane

2008-04-01

This study presents a low-cost plastic optical fiber sensor for the dual sensing of temperature and oxygen. The sensor features a commercially available epoxy glue coated on the side-polished fiber surface for temperature sensing and a fluorinated xerogel doped with platinum tetrakis pentrafluoropheny porphine (PtTFPP) coated on the fiber end for oxygen sensing. The temperature and oxygen indicators are both excited using a UV LED light source with a wavelength of 380 nm. The luminescence emission spectra of the two indicators are well resolved and exhibit no cross-talk effects. Overall, the results indicate that the dual sensor presented in this study provides an ideal solution for the non-contact, simultaneous sensing of temperature and oxygen in general biological and medical applications.

Stability of Glass Fiber-Plastic Composites

DTIC Science & Technology

1974-11-01

miniiiii’ 5 0712 01016774 9 x TECHNICA. . LIBRARY Jt U*Al>/l 1 Technical Report RL-75-6 STABILITY OF GLASS FIBER -PLASTIC COMPOSITES Wartan A...Subtitle) STABILITY OF GLASS FIBER -PLASTIC COMPOSITES 5. TYPE OF REPORT & PERIOD COVERED Technical Report 6. PERFORMING ORG. REPORT NUMBER 7...Exploratory research was conducted to determine the stages and nature of degradation of glass fiber -plastic composite systems under various environmental

Enhanced photocatalytic activity of wool fibers having titanium dioxide nanoparticles formed inside their cortex.

PubMed

Zhang, Hui; Sun, Runjun; Wu, Hailiang; Mao, Ningtao

2018-05-01

A wool-TiO2 nanoparticle composite material having TiO2 nanoparticles both infiltrated in the matrix between macrofibrils inside cortical cells of wool fibers and grafted on the fiber surface is obtained in this study, and the wool-nanoparticle composite material is found to have highly photocatalytic activities with an extremely narrow band gap of 2.8 eV. The wool fibers are obtained using three successive technical steps: wool fibers are swollen by using lithium bromide, then saturated with tetrabutyl titanate ethanol solution and subsequently treated in boiling water. It was demonstrated that the chemical bonds formed between the as-synthesized TiO2 nanoparticles and the wool fibers swollen by lithium bromide include C-Ti4+(Ti3+), N-Ti4+(Ti3+), O-Ti3+, and S-Ti4+(Ti3+) bonds. The modified wool fibers have shown markedly improved photocatalytic efficiency due to their enhanced visible light absorption capability, which is much better than the (N-doped) TiO2 coated wool fibers. In contrast, TiO2 modified wool fibers swollen by using formic acid have poorer photoactivity, this might be due to the elimination of trivalent titanium between TiO2 nanoparticles and the wool fibers. © 2018 IOP Publishing Ltd.

Enhanced photocatalytic activity of wool fibers having titanium dioxide nanoparticles formed inside their cortex

NASA Astrophysics Data System (ADS)

Zhang, Hui; Sun, Runjun; Wu, Hailiang; Mao, Ningtao

2018-07-01

A wool-TiO2 nanoparticle composite material having TiO2 nanoparticles both infiltrated in the matrix between macrofibrils inside cortical cells of wool fibers and grafted on the fiber surface is obtained in this study, and the wool-nanoparticle composite material is found to have highly photocatalytic activities with an extremely narrow band gap of 2.8 eV. The wool fibers are obtained using three successive technical steps: wool fibers are swollen by using lithium bromide, then saturated with tetrabutyl titanate ethanol solution and subsequently treated in boiling water. It was demonstrated that the chemical bonds formed between the as-synthesized TiO2 nanoparticles and the wool fibers swollen by lithium bromide include C‑Ti4+(Ti3+), N‑Ti4+(Ti3+), O‑Ti3+, and S‑Ti4+(Ti3+) bonds. The modified wool fibers have shown markedly improved photocatalytic efficiency due to their enhanced visible light absorption capability, which is much better than the (N-doped) TiO2 coated wool fibers. In contrast, TiO2 modified wool fibers swollen by using formic acid have poorer photoactivity, this might be due to the elimination of trivalent titanium between TiO2 nanoparticles and the wool fibers.

Coating Carbon Fibers With Platinum

NASA Technical Reports Server (NTRS)

Effinger, Michael R.; Duncan, Peter; Coupland, Duncan; Rigali, Mark J.

2007-01-01

A process for coating carbon fibers with platinum has been developed. The process may also be adaptable to coating carbon fibers with other noble and refractory metals, including rhenium and iridium. The coated carbon fibers would be used as ingredients of matrix/fiber composite materials that would resist oxidation at high temperatures. The metal coats would contribute to oxidation resistance by keeping atmospheric oxygen away from fibers when cracks form in the matrices. Other processes that have been used to coat carbon fibers with metals have significant disadvantages: Metal-vapor deposition processes yield coats that are nonuniform along both the lengths and the circumferences of the fibers. The electrical resistivities of carbon fibers are too high to be compatible with electrolytic processes. Metal/organic vapor deposition entails the use of expensive starting materials, it may be necessary to use a furnace, and the starting materials and/or materials generated in the process may be hazardous. The present process does not have these disadvantages. It yields uniform, nonporous coats and is relatively inexpensive. The process can be summarized as one of pretreatment followed by electroless deposition. The process consists of the following steps: The surfaces of the fiber are activated by deposition of palladium crystallites from a solution. The surface-activated fibers are immersed in a solution that contains platinum. A reducing agent is used to supply electrons to effect a chemical reduction in situ. The chemical reduction displaces the platinum from the solution. The displaced platinum becomes deposited on the fibers. Each platinum atom that has been deposited acts as a catalytic site for the deposition of another platinum atom. Hence, the deposition process can also be characterized as autocatalytic. The thickness of the deposited metal can be tailored via the duration of immersion and the chemical activity of the solution.

Sonochemical coating of paper by microbiocidal silver nanoparticles.

PubMed

Gottesman, Ronen; Shukla, Sourabh; Perkas, Nina; Solovyov, Leonid A; Nitzan, Yeshayahu; Gedanken, Aharon

2011-01-18

Colloidal silver has gained wide acceptance as an antimicrobial agent, and various substrates coated with nanosilver such as fabrics, plastics, and metal have been shown to develop antimicrobial properties. Here, a simple method to develop coating of colloidal silver on paper using ultrasonic radiation is presented, and the coatings are characterized using X-ray diffraction (XRD), high resolution scanning electron microscope (HRSEM), and thermogravimetry (TGA) measurements. Depending on the variables such as precursor concentrations and ultrasonication time, uniform coatings ranging from 90 to 150 nm in thickness have been achieved. Focused ion beam (FIB) cross section imaging measurements revealed that silver nanoparticles penetrated the paper surface to a depth of more than 1 μm, resulting in highly stable coatings. The coated paper demonstrated antibacterial activity against E. coli and S. aureus, suggesting its potential application as a food packing material for longer shelf life.

Fibers based on polyethylene with silicon and silicon carbide nanoparticles

NASA Astrophysics Data System (ADS)

Olkhov, A. A.; Krutikova, A. A.; Kovaleva, A. N.; Rychagov, O. V.; Ischenko, A. A.

2017-12-01

In the paper, fibrous materials based on polyethylene with nanosized silicon and silicon carbide obtained by the plasma chemical method have been obtained. The concentration of nanosilicon nanoparticles was 0.1-1.5%. Fibers absorb UV radiation in the range 200-400 nm. The size of silicon nanoparticles and dispersion in fibers are estimated by X-ray diffraction. It is shown that silicon nanoparticles exert no effect on the formation of the internal structure of the PE matrix. The degree of crystallinity, melting and crystallization temperatures remain constant. The surface properties of films are investigated by triboelectric methods and by determining the wetting angle. The surface properties of composite films do not differ from the properties of PE films with the concentration of nanoparticles from 0.1 to 1.0%. At a 1.5% content of n-SiC, the microrelief of the surface changes, and the friction coefficient of the films increases. The resulting films are recommended for application as a UV protective coating.

Evanescent wave assisted nanomaterial coating.

PubMed

Mondal, Samir K; Pal, Sudipta Sarkar; Kumbhakar, Dharmadas; Tiwari, Umesh; Bhatnagar, Randhir

2013-08-01

In this work we present a novel nanomaterial coating technique using evanescent wave (EW). The gradient force in the EW is used as an optical tweezer for tweezing and self-assembling nanoparticles on the source of EW. As a proof of the concept, we have used a laser coupled etched multimode optical fiber, which generates EW for the EW assisted coating. The section-wise etched multimode optical fiber is horizontally and superficially dipped into a silver/gold nanoparticles solution while the laser is switched on. The fiber is left until the solution recedes due to evaporation leaving the fiber in air. The coating time usually takes 40-50 min at room temperature. The scanning electron microscope image shows uniform and thin coating of self-assembled nanoparticles due to EW around the etched section. A coating thickness <200 nm is achieved. The technique could be useful for making surface-plasmon-resonance-based optical fiber probes and other plasmonic circuits.

Carbide coated fibers in graphite-aluminum composites

NASA Technical Reports Server (NTRS)

Imprescia, R. J.; Levinson, L. S.; Reiswig, R. D.; Wallace, T. C.; Williams, J. M.

1975-01-01

The NASA-supported program at the Los Alamos Scientific Laboratory (LASL) to develop carbon fiber-aluminum matrix composites is described. Chemical vapor deposition (CVD) was used to uniformly deposit thin, smooth, continuous coats of TiC on the fibers of graphite tows. Wet chemical coating of fibers, followed by high-temperature treatment, was also used, but showed little promise as an alternative coating method. Strength measurements on CVD coated fiber tows showed that thin carbide coats can add to fiber strength. The ability of aluminum alloys to wet TiC was successfully demonstrated using TiC-coated graphite surfaces. Pressure-infiltration of TiC- and ZrC-coated fiber tows with aluminum alloys was only partially successful. Experiments were performed to evaluate the effectiveness of carbide coats on carbon as barriers to prevent reaction between alluminum alloys and carbon. Initial results indicate that composites of aluminum and carbide-coated graphite are stable for long periods of time at temperatures near the alloy solidus.

Electron-Beam Irradiation Effect on Thermal and Mechanical Properties of Nylon-6 Nanocomposite Fibers Infused with Diamond and Diamond Coated Carbon Nanotubes

NASA Astrophysics Data System (ADS)

Imam, Muhammad A.; Jeelani, Shaik; Rangari, Vijaya K.; Gome, Michelle G.; Moura, Esperidiana. A. B.

2016-02-01

Nylon-6 is an engineering plastic with excellent properties and processability, which are essential in several industrial applications. The addition of filler such as diamond (DN) and diamond coated carbon nanotubes (CNTs) to form molded composites may increase the range of Nylon-6 applications due to the resulting increase in strength. The effects of electron-beam irradiation on these thermoplastic nanocomposites are either increase in the cross-linking or causes chain scission. In this study, DN-coated CNTs were synthesized using the sonochemical technique in the presence of cationic surfactant cetyltrimethyl ammonium bromide (CTAB). The DN-coated CNTs nanoparticles and diamond nanoparticles were then introduced into Nylon-6 polymer through a melt extrusion process to form nanocomposite fibers. They were further tested for their mechanical (Tensile) and thermal properties (thermogravimetric analysis (TGA), differential scanning calorimetry (DSC)). These composites were further exposed to the electron-beam (160kGy, 132kGy and 99kGy) irradiation using a 1.5MeV electron-beam accelerator, at room temperature, in the presence of air and tested for their thermal and mechanical properties. The best ultimate tensile strength was found to be 690MPa and 864MPa irradiated at 132 for DN/CNTs/Nylon-6 and Diamond/Nylon-6 nanocomposite fiber as compared to 346MPa and 321MPa for DN/CNTs/Nylon-6 and Diamond/Nylon-6 nanocomposite fiber without irradiation. The neat Nylon-6 tensile strength was 240MPa. These results are consistent with the activation energy calculated from TGA graphs. DSC analysis result shows that the slight increase in glass transition temperature (Tg) and decrease in melting temperature (Tm) which was expected from high electron-beam radiation dose.

Fabrication and Anti-Oxidation Ability of SiC-SiO₂ Coated Carbon Fibers Using Sol-Gel Method.

PubMed

Yang, Guangyuan; Huang, Zhixiong; Wang, Xu; Wang, Bo

2018-02-27

The paper proposed a method to improve the anti-oxidation performance of carbon fibers (CF) at high temperature environment by coating silicon dioxide (SiO₂) and silicon carbide (SiC). The modified sol-gel method had been used to ensure the proper interface between fibers and coating. We used polydimethylsiloxane and ethyl orthosilicate to make stable emulsion to uniformly disperse SiC nanoparticles. The modified SiO₂/SiC coating had been coated on CF successfully. Compared with the untreated CF, the coated fibers started to be oxidized around 900 °C and the residual weight was 57% at 1400 °C. The oxidation mechanism had been discussed. The structure of SiC/SiO₂ coated CF had been characterized by scanning electron microscope and X-ray diffraction analysis. Thermal gravimetric analysis was used to test the anti-oxidation ability of CF with different coatings.

Magnet-induced temporary superhydrophobic coatings from one-pot synthesized hydrophobic magnetic nanoparticles.

PubMed

Fang, Jian; Wang, Hongxia; Xue, Yuhua; Wang, Xungai; Lin, Tong

2010-05-01

In this paper, we report on the production of superhydrophobic coatings on various substrates (e.g., glass slide, silicon wafer, aluminum foil, plastic film, nanofiber mat, textile fabrics) using hydrophobic magnetic nanoparticles and a magnet-assembly technique. Fe(3)O(4) magnetic nanoparticles functionalized with a thin layer of fluoroalkyl silica on the surface were synthesized by one-step coprecipitation of Fe(2+)/Fe(3+) under an alkaline condition in the presence of a fluorinated alkyl silane. Under a magnetic field, the magnetic nanoparticles can be easily deposited on any solid substrate to form a thin superhydrophobic coating with water contact angle as high as 172 degrees , and the surface superhydrophobicity showed very little dependence on the substrate type. The particulate coating showed reasonable durability because of strong aggregation effect of nanoparticles, but the coating layer can be removed (e.g., by ultrasonication) to restore the original surface feature of the substrates. By comparison, the thin particle layer deposited under no magnetic field showed much lower hydrophobicity. The main reason for magnet-induced superhydrophobic surfaces is the formation of nano- and microstructured surface features. Such a magnet-induced temporary superhydrophobic coating may have wide applications in electronic, biomedical, and defense-related areas.

Examination of tapered plastic multimode fiber-based sensor performance with silver coating for different concentrations of calcium hypochlorite by soft computing methodologies--a comparative study.

PubMed

Zakaria, Rozalina; Sheng, Ong Yong; Wern, Kam; Shamshirband, Shahaboddin; Wahab, Ainuddin Wahid Abdul; Petković, Dalibor; Saboohi, Hadi

2014-05-01

A soft methodology study has been applied on tapered plastic multimode sensors. This study basically used tapered plastic multimode fiber [polymethyl methacrylate (PMMA)] optics as a sensor. The tapered PMMA fiber was fabricated using an etching method involving deionized water and acetone to achieve a waist diameter and length of 0.45 and 10 mm, respectively. In addition, a tapered PMMA probe, which was coated by silver film, was fabricated and demonstrated using a calcium hypochlorite (G70) solution. The working mechanism of such a device is based on the observation increment in the transmission of the sensor that is immersed in solutions at high concentrations. As the concentration was varied from 0 to 6 ppm, the output voltage of the sensor increased linearly. The silver film coating increased the sensitivity of the proposed sensor because of the effective cladding refractive index, which increases with the coating and thus allows more light to be transmitted from the tapered fiber. In this study, the polynomial and radial basis function (RBF) were applied as the kernel function of the support vector regression (SVR) to estimate and predict the output voltage response of the sensors with and without silver film according to experimental tests. Instead of minimizing the observed training error, SVR_poly and SVR_rbf were used in an attempt to minimize the generalization error bound so as to achieve generalized performance. An adaptive neuro-fuzzy interference system (ANFIS) approach was also investigated for comparison. The experimental results showed that improvements in the predictive accuracy and capacity for generalization can be achieved by the SVR_poly approach in comparison to the SVR_rbf methodology. The same testing errors were found for the SVR_poly approach and the ANFIS approach.

FRP MODEL - VERSION 1.0 FOR ESTIMATING STYRENE EMISSIONS FROM FIBER-REINFORCED PLASTICS FABRICATION PROCESSES

EPA Science Inventory

This software estimates styrene emissions from the manufacture of fiber-reinforced plastics/composite (FRP/C) products. In using the model, the user first chooses the appropriate process: gel coating, resin sprayup, hand layup, etc. Choosing a process will cause the 'baseline' in...

Thermally stable silica-coated hydrophobic gold nanoparticles.

PubMed

Kanehara, Masayuki; Watanabe, Yuka; Teranishi, Toshiharu

2009-01-01

We have successfully developed a method for silica coating on hydrophobic dodecanethiol-protected Au nanoparticles with coating thickness ranging from 10 to 40 nm. The formation of silica-coated Au nanoparticles could be accomplished via the preparation of hydrophilic Au nanoparticle micelles by cationic surfactant encapsulation in aqueous phase, followed by hydrolysis of tetraethylorthosilicate on the hydrophilic surface of gold nanoparticle micelles. Silica-coated Au nanoparticles exhibited quite high thermal stability, that is, no agglomeration of the Au cores could be observed after annealing at 600 degrees C for 30 min. Silica-coated Au nanoparticles could serve as a template to derive hollow nanoparticles. An addition of NaCN solution to silica-coated Au nanoparticles led the formation of hollow silica nanoparticles, which were redispersible in deionized water. The formation of the hollow silica nanoparticles results from the mesoporous structures of the silica shell and such a mesoporous structure is applicable to both catalyst support and drug delivery.

Functionalization of a long period grating coated with gold nanoparticles for glyphosate detection

NASA Astrophysics Data System (ADS)

Heidemann, Bárbara R.; Pereira, Júlia C.; Chiamenti, Ismael; Oliveira, Marcela M.; Muller, Marcia; Fabris, José L.

2017-04-01

This work describes a method for producing a nanostructured fiber optic device for sensing of pesticides in water environment. The device consists of a long period grating with a coating of gold nanoparticles functionalized with cysteamine. The LPG shows attenuation bands near the phase matching turning point at the visible spectral range. A bottom-up production route was used to deposit gold nanoparticles on the fiber surface. Sensitivity to the refractive index of the external medium was measured before and after the layer deposition. Cysteamine was used as a ligand for glyphosate present in water at a concentration of 100 μM.

Fabrication and Anti-Oxidation Ability of SiC-SiO2 Coated Carbon Fibers Using Sol-Gel Method

PubMed Central

Yang, Guangyuan; Huang, Zhixiong; Wang, Xu; Wang, Bo

2018-01-01

The paper proposed a method to improve the anti-oxidation performance of carbon fibers (CF) at high temperature environment by coating silicon dioxide (SiO2) and silicon carbide (SiC). The modified sol-gel method had been used to ensure the proper interface between fibers and coating. We used polydimethylsiloxane and ethyl orthosilicate to make stable emulsion to uniformly disperse SiC nanoparticles. The modified SiO2/SiC coating had been coated on CF successfully. Compared with the untreated CF, the coated fibers started to be oxidized around 900 °C and the residual weight was 57% at 1400 °C. The oxidation mechanism had been discussed. The structure of SiC/SiO2 coated CF had been characterized by scanning electron microscope and X-ray diffraction analysis. Thermal gravimetric analysis was used to test the anti-oxidation ability of CF with different coatings. PMID:29495499

Steady flow and heat transfer analysis of Phan-Thein-Tanner fluid in double-layer optical fiber coating analysis with Slip Conditions

NASA Astrophysics Data System (ADS)

Khan, Zeeshan; Shah, Rehan Ali; Islam, Saeed; Jan, Bilal; Imran, Muhammad; Tahir, Farisa

2016-10-01

Modern optical fibers require double-layer coating on the glass fiber to provide protection from signal attenuation and mechanical damage. The most important plastic resins used in wires and optical fibers are plastic polyvinyl chloride (PVC) and low-high density polyethylene (LDPE/HDPE), nylon and Polysulfone. In this paper, double-layer optical fiber coating is performed using melt polymer satisfying PTT fluid model in a pressure type die using wet-on-wet coating process. The assumption of fully developed flow of Phan-Thien-Tanner (PTT) fluid model, two-layer liquid flows of an immiscible fluid is modeled in an annular die, where the fiber is dragged at a higher speed. The equations characterizing the flow and heat transfer phenomena are solved exactly and the effects of emerging parameters (Deborah and slip parameters, characteristic velocity, radii ratio and Brinkman numbers on the axial velocity, flow rate, thickness of coated fiber optics, and temperature distribution) are reported in graphs. It is shown that an increase in the non-Newtonian parameters increase the velocity in the absence or presence of slip parameters which coincides with related work. The comparison is done with experimental work by taking λ → 0 (non-Newtonian parameter).

Steady flow and heat transfer analysis of Phan-Thein-Tanner fluid in double-layer optical fiber coating analysis with Slip Conditions.

PubMed

Khan, Zeeshan; Shah, Rehan Ali; Islam, Saeed; Jan, Bilal; Imran, Muhammad; Tahir, Farisa

2016-10-06

Modern optical fibers require double-layer coating on the glass fiber to provide protection from signal attenuation and mechanical damage. The most important plastic resins used in wires and optical fibers are plastic polyvinyl chloride (PVC) and low-high density polyethylene (LDPE/HDPE), nylon and Polysulfone. In this paper, double-layer optical fiber coating is performed using melt polymer satisfying PTT fluid model in a pressure type die using wet-on-wet coating process. The assumption of fully developed flow of Phan-Thien-Tanner (PTT) fluid model, two-layer liquid flows of an immiscible fluid is modeled in an annular die, where the fiber is dragged at a higher speed. The equations characterizing the flow and heat transfer phenomena are solved exactly and the effects of emerging parameters (Deborah and slip parameters, characteristic velocity, radii ratio and Brinkman numbers on the axial velocity, flow rate, thickness of coated fiber optics, and temperature distribution) are reported in graphs. It is shown that an increase in the non-Newtonian parameters increase the velocity in the absence or presence of slip parameters which coincides with related work. The comparison is done with experimental work by taking λ → 0 (non-Newtonian parameter).

Steady flow and heat transfer analysis of Phan-Thein-Tanner fluid in double-layer optical fiber coating analysis with Slip Conditions

PubMed Central

Khan, Zeeshan; Shah, Rehan Ali; Islam, Saeed; Jan, Bilal; Imran, Muhammad; Tahir, Farisa

2016-01-01

Modern optical fibers require double-layer coating on the glass fiber to provide protection from signal attenuation and mechanical damage. The most important plastic resins used in wires and optical fibers are plastic polyvinyl chloride (PVC) and low-high density polyethylene (LDPE/HDPE), nylon and Polysulfone. In this paper, double-layer optical fiber coating is performed using melt polymer satisfying PTT fluid model in a pressure type die using wet-on-wet coating process. The assumption of fully developed flow of Phan-Thien-Tanner (PTT) fluid model, two-layer liquid flows of an immiscible fluid is modeled in an annular die, where the fiber is dragged at a higher speed. The equations characterizing the flow and heat transfer phenomena are solved exactly and the effects of emerging parameters (Deborah and slip parameters, characteristic velocity, radii ratio and Brinkman numbers on the axial velocity, flow rate, thickness of coated fiber optics, and temperature distribution) are reported in graphs. It is shown that an increase in the non-Newtonian parameters increase the velocity in the absence or presence of slip parameters which coincides with related work. The comparison is done with experimental work by taking λ → 0 (non-Newtonian parameter). PMID:27708412

Carbothermal synthesis of coatings on silicon carbide fibers

NASA Astrophysics Data System (ADS)

Chen, Linlin

Four kinds of protective coatings---carbide derived carbon (CDC), boron nitride (BN), Al-O-N and BN doped Al-O-N (BAN) have been successfully synthesized on the surface of SiC fibers on the target to enhance the mechanical properties and oxidation resistance of the coated SiC fibers for the application as the reinforcements in the Ceramic Matrix Composites (CMCs) in the high temperatures. First of all, CDC coatings have been uniformly produced on Tyranno ZMI SiC fibers with good thickness control within nanometer accuracy by the chlorination in the temperature range of 550--700°C at atmospheric pressure. Kinetics of the carbon coating growth on the fibers has been systematically studied and thus a good foundation was set up for the further coating synthesis. BN coatings have been synthesized on the surface of SiC powders, fibers and fabrics by a novel carbothermal nitridation method. Non-bridging has been achieved in the BN-coated fiber tows by the nitridation in ammonia at atmospheric pressure in a temperature below 1200°C, which is lower compared to the traditional BN synthesis method and does not cause the degradation of the coated-fibers. BN coatings on the carbon nanotubes have also been formed and unlike the common methods, no additional dopant (such as metal catalyst) is introduced into the system during the BN coatings syntheses, thus the contamination of the final product is avoided. A novel Al-O-N coating has been explored with the most impressive point is that a more than 65% improvement in the tensile strength (up to ˜5.1GPa) and a three-time increase in the Weibull modulus compared to the as-received fibers are resulted by the formation of 200nm Al-O-N coating on the SiC fibers. It exceeds the strength of all other small diameter SiC fibers reported in the literature. Furthermore, BAN coating has also been produced on the surface of SiC fibers and about 20% enhancement in mechanical strength is achieved compared to that of the original fibers

Localized surface plasmon resonance-based fiber-optic sensor for the detection of triacylglycerides using silver nanoparticles.

PubMed

Baliyan, Anjli; Usha, Sruthi Prasood; Gupta, Banshi D; Gupta, Rani; Sharma, Enakshi Khular

2017-10-01

A label-free technique for the detection of triacylglycerides by a localized surface plasmon resonance (LSPR)-based biosensor is demonstrated. An LSPR-based fiber-optic sensor probe is fabricated by immobilizing lipase enzyme on silver nanoparticles (Ag-NPs) coated on an unclad segment of a plastic clad optical fiber. The size and shape of nanoparticles were characterized by high-resolution transmission electron microscopy and UV-visible spectroscopy. The peak absorbance wavelength changes with concentration of triacylglycerides surrounding the sensor probe, and sensitivity is estimated from shift in the peak absorbance wavelength as a function of concentration. The fabricated sensor was characterized for the concentration of triacylglyceride solution in the range 0 to 7 mM. The sensor shows the best sensitivity at a temperature of 37°C and pH 7.4 of the triacylglycerides emulsion with a response time of 40 s. A sensitivity of 28.5  nm/mM of triacylglyceride solution is obtained with a limit of detection of 0.016 mM in the entire range of triacylglycerides. This compact biosensor shows good selectivity, stability, and reproducibility in the entire physiological range of triacylglycerides and is well-suited to real-time online monitoring and remote sensing. (2017) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE).

Localized surface plasmon resonance-based fiber-optic sensor for the detection of triacylglycerides using silver nanoparticles

NASA Astrophysics Data System (ADS)

Baliyan, Anjli; Usha, Sruthi Prasood; Gupta, Banshi D.; Gupta, Rani; Sharma, Enakshi Khular

2017-10-01

A label-free technique for the detection of triacylglycerides by a localized surface plasmon resonance (LSPR)-based biosensor is demonstrated. An LSPR-based fiber-optic sensor probe is fabricated by immobilizing lipase enzyme on silver nanoparticles (Ag-NPs) coated on an unclad segment of a plastic clad optical fiber. The size and shape of nanoparticles were characterized by high-resolution transmission electron microscopy and UV-visible spectroscopy. The peak absorbance wavelength changes with concentration of triacylglycerides surrounding the sensor probe, and sensitivity is estimated from shift in the peak absorbance wavelength as a function of concentration. The fabricated sensor was characterized for the concentration of triacylglyceride solution in the range 0 to 7 mM. The sensor shows the best sensitivity at a temperature of 37°C and pH 7.4 of the triacylglycerides emulsion with a response time of 40 s. A sensitivity of 28.5 nm/mM of triacylglyceride solution is obtained with a limit of detection of 0.016 mM in the entire range of triacylglycerides. This compact biosensor shows good selectivity, stability, and reproducibility in the entire physiological range of triacylglycerides and is well-suited to real-time online monitoring and remote sensing.

Carbide coated fibers in graphite-aluminum composites

NASA Technical Reports Server (NTRS)

Imprescia, R. J.; Levinson, L. S.; Reiswig, R. D.; Wallace, T. C.; Williams, J. M.

1975-01-01

Thin, uniform coats of titanium carbide, deposited on graphite fibers by chemical vapor deposition with thicknesses up to approximately 0.1 microns were shown to improve fiber strength significantly. For greater thicknesses, strength was degraded. The coats promote wetting of the fibers and infiltration of the fiber yarns with aluminum alloys, and act as protective barriers to inhibit reaction between the fibers and the alloys. Chemical vapor deposition was used to produce silicon carbide coats on graphite fibers. In general, the coats were nonuniform and were characterized by numerous surface irregularities. Despite these irregularities, infiltration of these fibers with aluminum alloys was good. Small graphite-aluminum composite samples were produced by vacuum hot-pressing of aluminum-infiltrated graphite yarn at temperatures above the metal liquidus.

Optical Sensors Based on Plastic Fibers

PubMed Central

Bilro, Lúcia; Alberto, Nélia; Pinto, João L.; Nogueira, Rogério

2012-01-01

The recent advances of polymer technology allowed the introduction of plastic optical fiber in sensor design. The advantages of optical metrology with plastic optical fiber have attracted the attention of the scientific community, as they allow the development of low-cost or cost competitive systems compared with conventional technologies. In this paper, the current state of the art of plastic optical fiber technology will be reviewed, namely its main characteristics and sensing advantages. Several measurement techniques will be described, with a strong focus on interrogation approaches based on intensity variation in transmission and reflection. The potential applications involving structural health monitoring, medicine, environment and the biological and chemical area are also presented. PMID:23112707

Optical sensors based on plastic fibers.

PubMed

Bilro, Lúcia; Alberto, Nélia; Pinto, João L; Nogueira, Rogério

2012-01-01

The recent advances of polymer technology allowed the introduction of plastic optical fiber in sensor design. The advantages of optical metrology with plastic optical fiber have attracted the attention of the scientific community, as they allow the development of low-cost or cost competitive systems compared with conventional technologies. In this paper, the current state of the art of plastic optical fiber technology will be reviewed, namely its main characteristics and sensing advantages. Several measurement techniques will be described, with a strong focus on interrogation approaches based on intensity variation in transmission and reflection. The potential applications involving structural health monitoring, medicine, environment and the biological and chemical area are also presented.

Stripping and splicing polyimide-coated fibers

NASA Astrophysics Data System (ADS)

Duke, Douglas; Kanda, Yoshiharu; Tobita, Kenyo; Yamauchi, Ryozo

2011-05-01

Polyimide is often used as a coating material for optical fibers used in high temperature environments such as aerospace or oil and gas sensor applications. Unfortunately, polyimide coating is very difficult to strip by conventional mechanical stripping methods. The glass fiber is easily damaged if the stripping process is not extremely well controlled. Stripping the polyimide coating by heating with a flame or arc typically results in a significant reduction in fiber strength. Strength may be maintained by using hot acid stripping, however the use of the strong hot acid presents safety hazards and also requires controlled and safe waste disposal. Another issue with polyimide coating is variability of the coating diameter from various manufacturers or due to different polyimide coating processes. This not only complicates the polyimide stripping issue, but also presents problems with precise clamping and alignment during splicing, especially when it is necessary to splice with a short cleave length. In this paper, we present new polyimide coating stripping technology. The significant feature of this stripping technology is achievement of good strength while avoiding the use of hot acid or heating. We also developed a new specialty fiber fusion splicer that enables precise alignment and splicing regardless of the variability of polyimide coating diameter, even when clamping on the coating.

PLASTIC SHRINKAGE CONTROLLING EFFECT BY POLYPROPYLENE SHORT FIBER WITH HYDROPHILY

NASA Astrophysics Data System (ADS)

Hosoda, Akira; Sadatsuki, Yoshitomo; Oshima, Akihiro; Ishii, Akina; Tsubaki, Tatsuya

The aim of this research is to clarify the mechanism of controlling plastic shrinkage crack by adding small amout of synthetic short fiber, and to propose optimum polypropylene short fiber to control plastic shrinkage crack. In this research, the effect of the hydrophily of polypropylene fiber was investigated in the amount of plastic shrinkage of mortar, total area of plastic shrinkage crack, and bond properties between fiber and mortar. The plastic shrinkage test of morar was conducted under high temperature, low relative humidity, and constant wind velocity. When polypropylene fiber had hydrophily, the amount of plastic shrinkage of mortar was restrained, which was because cement paste in morar was captured by hydrophilic fiber and then bleeding of mortar was restrained. With hydrophily, plastic shrinkage of mortar was restrained and bridging effect was improved due to better bond, which led to remarkable reduction of plastic shrinkage crack. Based on experimental results, the way of developing optimum polypropylene short fiber for actual construction was proposed. The fiber should have large hydrophily and small diameter, and should be used in as small amount as possible in order not to disturb workability of concrete.

Development and evaluation of antimicrobial activated carbon fiber filters using Sophora flavescens nanoparticles.

PubMed

Sim, Kyoung Mi; Kim, Kyung Hwan; Hwang, Gi Byoung; Seo, SungChul; Bae, Gwi-Nam; Jung, Jae Hee

2014-09-15

Activated carbon fiber (ACF) filters have a wide range of applications, including air purification, dehumidification, and water purification, due to their large specific surface area, high adsorption capacity and rate, and specific surface reactivity. However, when airborne microorganisms such as bacteria and fungi adhere to the carbon substrate, ACF filters can become a source of microbial contamination, and their filter efficacy declines. Antimicrobial treatments are a promising means of preventing ACF bio-contamination. In this study, we demonstrate the use of Sophora flavescens in antimicrobial nanoparticles coated onto ACF filters. The particles were prepared using an aerosol process consisting of nebulization-thermal drying and particle deposition. The extract from S. flavescens is an effective, natural antimicrobial agent that exhibits antibacterial activity against various pathogens. The efficiency of Staphylococcus epidermidis inactivation increased with the concentration of S. flavescens nanoparticles in the ACF filter coating. The gas adsorption efficiency of the coated antimicrobial ACF filters was also evaluated using toluene. The toluene-removal capacity of the ACF filters remained unchanged while the antimicrobial activity was over 90% for some nanoparticle concentrations. Our results provide a scientific basis for controlling both bioaerosol and gaseous pollutants using antimicrobial ACF filters coated with S. flavescens nanoparticles. Copyright © 2014 Elsevier B.V. All rights reserved.

Carbon nanotube and graphene nanoribbon-coated conductive Kevlar fibers.

PubMed

Xiang, Changsheng; Lu, Wei; Zhu, Yu; Sun, Zhengzong; Yan, Zheng; Hwang, Chi-Chau; Tour, James M

2012-01-01

Conductive carbon material-coated Kevlar fibers were fabricated through layer-by-layer spray coating. Polyurethane was used as the interlayer between the Kevlar fiber and carbon materials to bind the carbon materials to the Kevlar fiber. Strongly adhering single-walled carbon nanotube coatings yielded a durable conductivity of 65 S/cm without significant mechanical degradation. In addition, the properties remained stable after bending or water washing cycles. The coated fibers were analyzed using scanning electron microcopy and a knot test. The as-produced fiber had a knot efficiency of 23%, which is more than four times higher than that of carbon fibers. The spray-coating of graphene nanoribbons onto Kevlar fibers was also investigated. These flexible coated-Kevlar fibers have the potential to be used for conductive wires in wearable electronics and battery-heated armors. © 2011 American Chemical Society

Nanoparticle/Polymer Nanocomposite Bond Coat or Coating

NASA Technical Reports Server (NTRS)

Miller, Sandi G.

2011-01-01

This innovation addresses the problem of coatings (meant to reduce gas permeation) applied to polymer matrix composites spalling off in service due to incompatibility with the polymer matrix. A bond coat/coating has been created that uses chemically functionalized nanoparticles (either clay or graphene) to create a barrier film that bonds well to the matrix resin, and provides an outstanding barrier to gas permeation. There is interest in applying clay nanoparticles as a coating/bond coat to a polymer matrix composite. Often, nanoclays are chemically functionalized with an organic compound intended to facilitate dispersion of the clay in a matrix. That organic modifier generally degrades at the processing temperature of many high-temperature polymers, rendering the clay useless as a nano-additive to high-temperature polymers. However, this innovation includes the use of organic compounds compatible with hightemperature polymer matrix, and is suitable for nanoclay functionalization, the preparation of that clay into a coating/bondcoat for high-temperature polymers, the use of the clay as a coating for composites that do not have a hightemperature requirement, and a comparable approach to the preparation of graphene coatings/bond coats for polymer matrix composites.

[Carbon fiber-reinforced plastics as implant materials].

PubMed

Bader, R; Steinhauser, E; Rechl, H; Siebels, W; Mittelmeier, W; Gradinger, R

2003-01-01

Carbon fiber-reinforced plastics have been used clinically as an implant material for different applications for over 20 years.A review of technical basics of the composite materials (carbon fibers and matrix systems), fields of application,advantages (e.g., postoperative visualization without distortion in computed and magnetic resonance tomography), and disadvantages with use as an implant material is given. The question of the biocompatibility of carbon fiber-reinforced plastics is discussed on the basis of experimental and clinical studies. Selected implant systems made of carbon composite materials for treatments in orthopedic surgery such as joint replacement, tumor surgery, and spinal operations are presented and assessed. Present applications for carbon fiber reinforced plastics are seen in the field of spinal surgery, both as cages for interbody fusion and vertebral body replacement.

Carbide coated fibers in graphite-aluminum composites

NASA Technical Reports Server (NTRS)

Imprescia, R. J.; Levinson, L. S.; Reiswig, R. D.; Wallace, T. C.; Williams, J. M.

1975-01-01

The study of protective-coupling layers of refractory metal carbides on the graphite fibers prior to their incorporation into composites is presented. Such layers should be directly wettable by liquid aluminum and should act as diffusion barriers to prevent the formation of aluminum carbide. Chemical vapor deposition was used to uniformly deposit thin, smooth, continuous coats of ZrC on the carbon fibers of tows derived from both rayon and polyacrylonitrile. A wet chemical coating of the fibers, followed by high-temperature treatment, was used, and showed promise as an alternative coating method. Experiments were performed to demonstrate the ability of aluminum alloys to wet carbide surfaces. Titanium carbide, zirconium carbide and carbide-coated graphite surfaces were successfully wetted. Results indicate that initial attempts to wet surfaces of ZrC-coated carbon fibers appear successful.

[Study of Raman scattering of plastic optical fiber].

PubMed

Sun, Xiu-Ping; Feng, Ke-Cheng; Zhang, Xi-He; Tan, Yong; Zhang, Feng-Dong; Wang, Zhao-Min

2005-12-01

The first order stimulated Raman scattering (SRS) spectrum of PMMA plastic optical fiber was given, and the characteristic of the first order Stokes spectrum was studied. The threshold and the spectrum width were measured. The formation mechanism of SRS was analyzed, and then the first order Stokes spectrum of plastic optical fiber and that of silica fiber were compared.

Low-temperature-sensitive relative humidity sensor based on tapered square no-core fiber coated with SiO2 nanoparticles

NASA Astrophysics Data System (ADS)

Miao, Yinping; Ma, Xixi; He, Yong; Zhang, Hongmin; Zhang, Hao; Song, Binbin; Liu, Bo; Yao, Jianquan

2016-05-01

A low-temperature-sensitive relative humidity (RH) sensor based on multimode interference effects has been proposed. The sensor consists of a section of tapered square no-core fiber (TSNCF) coated with SiO2 nanoparticles which is fabricated by splicing the TSNCF with two single-mode fibers (SMFs). The refractive index of SiO2 nanoparticles changes with the variation of environmental humidity levels. Characteristics of the transmission spectral have been investigated under different humidity levels. The wavelength shifts up to 10.2 nm at 1410 nm and 11.5 nm at 1610 nm for a RH range of 43.6-98.6% have been experimentally achieved, and the corresponding sensitivities reach 456.21 pm/%RH and 584.2 pm/%RH for a RH range of 83-96.6%, respectively. The temperature response of the proposed sensor has also been experimentally investigated. Due to the fact that the sensing head is made of a pure silica rod with a low thermal expansion coefficient and the thermo-optic coefficient, the transmission spectrum shows a low temperature sensitivity of about 6 pm/°C for an environmental temperature of 20.9-80 °C, which is a desirable merit to resolve the temperature cross sensitivity. Therefore, the proposed sensor could be applied to breath analysis applications with low temperature fluctuations.

Antibacterial activity of plastics coated with silver-doped organic-inorganic hybrid coatings prepared by sol-gel processes.

PubMed

Marini, M; De Niederhausern, S; Iseppi, R; Bondi, M; Sabia, C; Toselli, M; Pilati, F

2007-04-01

Silver-doped organic-inorganic hybrid coatings were prepared starting from tetraethoxysilane- and triethoxysilane-terminated poly(ethylene glycol)-block-polyethylene by the sol-gel process. They were applied as a thin layer (0.6-1.1 microm) to polyethylene (PE) and poly(vinyl chloride) (PVC) films and the antibacterial activity of the coated films was tested against Gram-negative (Escherichia coli ATCC 25922) and Gram-positive (Staphylococcus aureus ATCC 6538) bacteria. The effect of several factors (such as organic-inorganic ratio, type of catalyst, time of post-curing, silver ion concentration, etc.) was investigated. Measurements at different contact times showed a rapid decrease of the viable count for both tested strains. The highest antibacterial activity [more than 6 log reduction within 6 h starting from 106 colony-forming units (cfu) mL-1] was obtained for samples with an organic-inorganic weight ratio of 80:20 and 5 wt % silver salt with respect to the coating. For the coatings prepared by an acid-catalyzed process, a high level of permanence of the antibacterial activity of the coated films was demonstrated by repeatedly washing the samples in warm water or by immersion in physiological saline solution at 37 degrees C for 3 days. The release of silver ions per square meter of coating is very similar to that previously observed for polyamides filled with metallic silver nanoparticles; however, when compared on the basis of Ag content, the concentration of silver ions released from the coating is much higher than that released from 1 mm thick specimens of polyamide (PA) filled with silver nanoparticles. Transparency and good adhesion of the coating to PE and PVC plastic substrates without any previous surface treatment are further interesting features.

U-bent plastic optical fiber based plasmonic biosensor for nucleic acid detection

NASA Astrophysics Data System (ADS)

Gowri, A.; Sai, V. V. R.

2017-05-01

This study presents the development of low cost, rapid and highly sensitive plasmonic sandwich DNA biosensor using U-bent plastic optical fiber (POF) probes with high evanescent wave absorbance sensitivity and gold nanoparticles (AuNP) as labels. Plastic optical fiber (PMMA core and fluorinated polymer as cladding) offer ease in machinability and handling due to which optimum U-bent geometry (with fiber and bend diameter of 0.5 and 1.5 mm respectively) for high sensitivity could be achieved. A sensitive fiber optic DNA biosensor is realized by (i) modifying the PMMA surface using ethylenediamine (EDA) in order to maximize the immobilization of capture oligonucleotides (ONs) and (ii) conjugating probe ONs to AuNP labels of optimum size ( 35 nm) with high extinction coefficient and optimal ON surface density. The sandwich hybridization assay on U-bent POF probes results in increase in optical absorbance through the probe with increase in target ON concentration due to the presence of increased number of AuNPs. The absorbance of light passing through the U-bent probe due to the presence of AuNP labels on its surface as result of sandwich DNA hybridization is measured using a halogen lamp and a fiber optic spectrometer. A picomolar limit of detection of target ON (0.2 pM or 1 pg/ml or 5 attomol in 25 μL) is achieved with this biosensing scheme, indicating its potential for the development of a highly sensitive DNA biosensor.

Engineering Design Handbook Short Fiber Plastic Base Composites

DTIC Science & Technology

1975-07-31

ENGINEERING DESIGN HANDBOOK N ’~rttl SHORT FIBER PLASTIC BASE COMPOSITES l ,.. HEADQUARTERS, US ARrm MAlERIEL COIVMAND JULY 1975 DEPARTMENT OF...HANDBOOK SHORT FIBER PLASTIC BASE COMPOSITES TABLE OF CONTENTS 31 July 1975 Paragraph Page 1-1 1-2 1-2.1 1-2.2 1-3 1-3.1 1-3.2 1-3.3 1...General ............................... . Molding Short Fiber Compounds ........... . Classification of Polymer Based Composites

Magnetism in nanoparticles: tuning properties with coatings.

PubMed

Crespo, Patricia; de la Presa, Patricia; Marín, Pilar; Multigner, Marta; Alonso, José María; Rivero, Guillermo; Yndurain, Félix; González-Calbet, José María; Hernando, Antonio

2013-12-04

This paper reviews the effect of organic and inorganic coatings on magnetic nanoparticles. The ferromagnetic-like behaviour observed in nanoparticles constituted by materials which are non-magnetic in bulk is analysed for two cases: (a) Pd and Pt nanoparticles, formed by substances close to the onset of ferromagnetism, and (b) Au and ZnO nanoparticles, which were found to be surprisingly magnetic at the nanoscale when coated by organic surfactants. An overview of theories accounting for this unexpected magnetism, induced by the nanosize influence, is presented. In addition, the effect of coating magnetic nanoparticles with biocompatible metals, oxides or organic molecules is also reviewed, focusing on their applications.

Easy and safe coated optical fiber direct connection without handling bare optical fiber

NASA Astrophysics Data System (ADS)

Saito, Kotaro; Kihara, Mitsuru; Shimizu, Tomoya; Kurashima, Toshio

2015-06-01

We propose a novel field installable splicing technique for the direct connection of 250 μm diameter coated optical fiber that does not require bare optical fiber to be handled. Our proposed technique can realize a low insertion loss over a wide field installation temperature range of -10-40 °C. The keys to coated optical fiber direct connection are a cleaving technique and a technique for removing coated optical fiber. As the cleaving technique, we employed a method where the fiber is stretched and then a blade is pushed perpendicularly against the stretched fiber. As a result we confirmed that fiber endfaces cleaved at -10-40 °C were all mirror endfaces. With the removal technique, the coating is removed inside the connecting component by incorporating a circular cone shaped coating removal part. A mechanical splice based on these techniques successfully achieved a low insertion loss of less than 0.11 dB and a return loss of more than 50 dB at -10, 20, and 40 °C. In addition, the temperature cycle characteristics were stable over a wide temperature range of -40-75 °C.

Measurement of large strains in ropes using plastic optical fibers

DOEpatents

Williams, Jerry Gene; Smith, David Barton; Muhs, Jeffrey David

2006-02-14

A method for the direct measurement of large strains in ropes in situ using a plastic optical fiber, for example, perfluorocarbon or polymethyl methacrylate and Optical Time-Domain Reflectometer or other light time-of-flight measurement instrumentation. Protective sheaths and guides are incorporated to protect the plastic optical fiber. In one embodiment, a small rope is braided around the plastic optical fiber to impose lateral compressive forces to restrain the plastic optical fiber from slipping and thus experience the same strain as the rope. Methods are described for making reflective interfaces along the length of the plastic optical fiber and to provide the capability to measure strain within discrete segments of the rope. Interpretation of the data allows one to calculate the accumulated strain at any point in time and to determine if the rope has experienced local damage.

Mixed polyvalent-monovalent metal coating for carbon-graphite fibers

NASA Technical Reports Server (NTRS)

Harper-Tervet, J.; Tervet, F. W.; Humphrey, M. F. (Inventor)

1982-01-01

An improved coating of gasification catalyst for carbon-graphite fibers is provided comprising a mixture of a polyvalent metal such as calcium and a monovalent metal such as lithium. The addition of lithium provides a lighter coating and a more flexible coating when applied to a coating of a carboxyl containing resin such as polyacrylic acid since it reduces the crosslink density. Furthermore, the presence of lithium provides a glass-like substance during combustion which holds the fiber together resulting in slow, even combustion with much reduced evolution of conductive fragments. The coated fibers are utilized as fiber reinforcement for composites.

Characterization of ecofriendly polyethylene fiber from plastic bag waste

NASA Astrophysics Data System (ADS)

Soekoco, Asril S.; Noerati, Komalasari, Maya; Kurniawan, Hananto, Agus

2017-08-01

This paper presents the characterization of fiber morphology, fiber count and tenacity of polyethylene fiber which is made from plastic bag waste. Recycling plastic bag waste into textile fiber has not developed yet. Plastic bag waste was recycled into fiber by melt spinning using laboratory scale melt spinning equipment with single orifice nozzle and plunger system. The basic principle of melt spinning is by melting materials and then extruding it through small orifice of a spinning nozzle to form fibers. Diameter and cross section shape of Recycled polyethylene fiber were obtained by using scanning electron microscope (SEM) instrumentation. Linear density of the recycled fiber were analyzed by calculation using denier and dTex formulation and The mechanical strength of the fibers was measured in accordance with the ASTM D 3379-75 standard. The cross section of recycled fiber is circular taking the shape of orifice. Fiber count of 303.75 denier has 1.84 g/denier tenacity and fiber count of 32.52 has 3.44 g/denier tenacity. This conditions is affected by the growth of polymer chain alignment when take-up axial velocity become faster. Recycled polyethylene fiber has a great potential application in non-apparel textile.

Toxicity testing of four silver nanoparticle-coated dental castings in 3-D LO2 cell cultures.

PubMed

Zhao, Yi-Ying; Chu, Qiang; Shi, Xu-Er; Zheng, Xiao-Dong; Shen, Xiao-Ting; Zhang, Yan-Zhen

To address the controversial issue of the toxicity of dental alloys and silver nanoparticles in medical applications, an in vivo-like LO2 3-D model was constructed within polyvinylidene fluoride hollow fiber materials to mimic the microenvironment of liver tissue. The use of microscopy methods and the measurement of liver-specific functions optimized the model for best cell performances and also proved the superiority of the 3-D LO2 model when compared with the traditional monolayer model. Toxicity tests were conducted using the newly constructed model, finding that four dental castings coated with silver nanoparticles were toxic to human hepatocytes after cell viability assays. In general, the toxicity of both the castings and the coated silver nanoparticles aggravated as time increased, yet the nanoparticles attenuated the general toxicity by preventing metal ion release, especially at high concentrations.

Factors Affecting the Discharge of Micro-Plastic Fibers from Household Laundry

NASA Astrophysics Data System (ADS)

Lange, N.

2017-12-01

Every day millions of loads of laundry are done in in the United States alone. Many, if not most, include synthetic fibers. During washing, micro-plastic fibers are released from the fabric, and discharged into the wastewater. These fibers have been detected in fresh water throughout the world and all of the oceans. These micro-plastic fibers are an emerging environmental contaminant that can adversely affect wildlife and are highly bio-accumulated in aquatic food-chains. Additionally, like other plastics, micro-fibers are not readily biodegraded and persist in the environment for a long time. In this research, I explored the effect of the way we wash clothes on the amount of micro-plastic fibers that are shed by common clothing materials containing man-made fibers. I collected discharge samples from wash and rinse cycles of a washing machine. I collected samples from a control wash using no detergent and then repeated five times. Next, I repeated the experiment five times using four different types of detergent. Large amounts of micro-plastic fibers were released during all wash cycles. However, the numbers decreased during the later rinse cycles. The use of laundry detergent increased the number of micro-plastic fibers released into the wash-water. Deep cleaning detergents produced over ten times more fibers than the no-detergent control. The gentlest detergent only released two times more fibers than the control. Therefore, it would be possible to affect the number of fibers released into the wastewater simply by selection of detergent. The ultimate goal of my research is to develop an optimized detergent that minimizes the number of micro-plastic fibers generated by washing and still effectively clean clothes.

Interfacial microstructure and mechanical properties of Cf/AZ91D composites with TiO2 and PyC fiber coatings.

PubMed

Li, Shaolin; Qi, Lehua; Zhang, Ting; Ju, Luyan; Li, Hejun

2017-10-01

In spite of the effectiveness of the fiber coatings on interface modification of carbon fiber reinforced magnesium matrix composites, the cost and exclusive equipment for the coatings preparation are usually ignored during research work. In this paper, pyrolytic carbon (PyC) and TiO 2 were coated on carbon fiber surface to study the effects of fiber coatings on interfacial microstructure and mechanical properties of carbon fiber reinforced AZ91D composites (C f /AZ91D composites). It was indicated that both the two coatings could modify the interface and improve the mechanical properties of the composites. The ultimate tensile strength of the TiO 2 -C f /AZ91D and the PyC-C f /AZ91D composite were 333MPa and 400MPa, which were improved by 41.7% and 70.2% respectively, compared with the untreated-C f /AZ91D composite. The microstructure observation revealed that the strengthening of the composites relied on fiber integrity and moderate interfacial bonding. MgO nano-particles were generated at the interface due to the reaction of TiO 2 with Mg in the TiO 2 -C f /AZ91D composite. The volume expansion resulting from the reaction let to disordered intergranular films and crystal defects at the interface. The fibers were protected and the interfacial reaction was restrained by PyC coating in the PyC-C f /AZ91D composite. The principle to select the coating of fiber was proposed by comparing the effectiveness and cost of the coatings. Copyright © 2017 Elsevier Ltd. All rights reserved.

Method for forming hermetic coatings for optical fibers

DOEpatents

Michalske, Terry A.; Rye, Robert R.; Smith, William L.

1993-01-01

A method for forming hermetic coatings on optical fibers by hot filament assisted chemical vapor deposition advantageously produces a desirable coating while maintaining the pristine strength of the pristine fiber. The hermetic coatings may be formed from a variety of substances, such as, for example, boron nitride and carbon.

Self-cleaning superhydrophobic epoxy coating based on fibrous silica-coated iron oxide magnetic nanoparticles.

PubMed

Alamri, Haleema; Al-Shahrani, Abdullah; Bovero, Enrico; Khaldi, Turki; Alabedi, Gasan; Obaid, Waleed; Al-Taie, Ihsan; Fihri, Aziz

2018-03-01

Inspired by the self-cleaning lotus leaf, a facile method of fabricating superhydrophobic silica coated magnetite nanoparticles using a cost-effective process is presented in this work. The structural characterizations and magnetic properties of the obtained core-shell magnetic nanoparticles were characterized by means of X-ray diffraction (XRD), thermal gravimetric analysis (TGA), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and vibrating sample magnetometer (VSM). TEM analysis revealed that the particles present flower-like dendrimeric fibers morphology. The particles were uniformly dispersed on the surface of an epoxy resin coating with the purpose to increase the roughness and reduce the surface energy of the surface. The resulting superhydrophobic surface provides robust water-repellent surface under harsh conditions, thanks to its self-cleaning characteristic. The superhydrophobicity of this surface was confirmed based on the measurements of a water contact angle around 175°, which surpasses the theoretical limit of the superhydrophobicity. The simplicity and the cost-effectiveness of the process developed in this study appears to be a promising route for the preparation of other magnetic superhydrophobic organic-inorganic hybrid materials that would be beneficial in a wide variety of applications. Copyright © 2017 Elsevier Inc. All rights reserved.

Heat suppression of the fiber coating on a cladding light stripper in high-power fiber laser.

PubMed

Yan, Ming-Jian; Wang, Zheng; Meng, Ling-Qiang; Yin, Lu; Han, Zhi-Gang; Shen, Hua; Wang, Hai-Lin; Zhu, Ri-Hong

2018-01-20

We present a theoretical model for the thermal effect of the fiber coating on a high-power cladding light stripper, which is fabricated by chemical etching. For the input and output of the fiber coating, a novel segmented corrosion method and increasing attenuation method are proposed for heat suppression, respectively. The relationship between the attenuation and temperature rise of the fiber coating at the output is experimentally demonstrated. The temperature distribution of the fiber coating at the input as well as the return light power caused by scattering are measured for the etched fiber with different surface roughness values. The results suggest that the rise in temperature is primarily caused by the scattering light propagating into the coating. Finally, an attenuation of 27 dB is achieved. At a room temperature of 23°C and input pump power of 438 W, the highest temperature of the input fiber coating decreases from 39.5°C to 27.9°C by segmented corrosion, and the temperature rise of the output fiber coating is close to 0.

Ceramic Fiber Coatings Development and Demonstration

DTIC Science & Technology

1993-05-28

from polycar- bosilane polymer . The fiber is mostly amorphous with some microcrystalline beta- SiC . A typical elemental composition (wt %) is 57... preceramic polymers yielded improvements mainly for oxide coatings and proved particularly promising for low cost processing. A schematic for this...deposition. COMPOSITE FABRICATION AND EVALUATION Coated fiber tows were infiltrated with Si 3N4 matrix by chemical vapor deposition in order to study

Synthesis and characterization of dextran-coated iron oxide nanoparticles

NASA Astrophysics Data System (ADS)

Predescu, Andra Mihaela; Matei, Ecaterina; Berbecaru, Andrei Constantin; Pantilimon, Cristian; Drăgan, Claudia; Vidu, Ruxandra; Predescu, Cristian; Kuncser, Victor

2018-03-01

Synthesis and characterization of iron oxide nanoparticles coated with a large molar weight dextran for environmental applications are reported. The first experiments involved the synthesis of iron oxide nanoparticles which were coated with dextran at different concentrations. The synthesis was performed by a co-precipitation technique, while the coating of iron oxide nanoparticles was carried out in solution. The obtained nanoparticles were characterized by using scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction spectrometry, Fourier transform infrared spectroscopy and superconducting quantum interference device magnetometry. The results demonstrated a successful coating of iron oxide nanoparticles with large molar weight dextran, of which agglomeration tendency depended on the amount of dextran in the coating solution. SEM and TEM observations have shown that the iron oxide nanoparticles are of about 7 nm in size.

Effect of addition of butyl benzyl phthalate plasticizer and zinc oxide nanoparticles on mechanical properties of cellulose acetate butyrate/organoclay biocomposite

NASA Astrophysics Data System (ADS)

Putra, B. A. P.; Juwono, A. L.; Rochman, N. T.

2017-07-01

Plastics as packaging materials and coatings undergo increasing demands globally each year. This pose a serious problem to the environment due to its difficulty to degrade. One solution to addressing the problem of plastic wastes is the use of bioplastics. According to the European Organization Bioplastic, one of the biodegradable plastics is derivative of cellulose. To improve mechanical properties of bioplastic, biocomposites are made with the addition of certain additives and fillers. The aim of this study is to investigate the effect of butyl benzyl phthalate plasticizer (BBP) and ZnO nanoparticles addition on mechanical properties of cellulose acetate butyrate (CAB) / organoclay biocomposite. ZnO nanoparticles synthesized from commercial ZnO precursor by using sol-gel size reduction method. ZnO was dissolved in a solution of citric acid in the ratio 1:1 to 1:5 to form zinc citrate. Zinc citrate then decomposed by calcination at temperature of 600oC. ZnO nanoparticles with an average size of 44.4 nm is obtained at a ratio of 1: 2. The addition of ZnO nanoparticles and BBP plasticizer was varied to determine the effect on the mechanical properties of biocomposite. The addition of 10 - 15 %wt ZnO nanoparticles and 30 - 40 %wt BBP plasticizer was studied to determine the effect on the tensile strength, elongation, and modulus elasticity of the biocomposites. Biocomposite films were made by using solution casting method with acetone as solvent. The addition of plasticizer BBP and ZnO nanoparticles by 30% and 10% made biocomposite has a tensile strength of 2.223 MPa.

Micromagnetic Simulation of Fibers and Coatings on Textiles

NASA Astrophysics Data System (ADS)

Ehrmann, Andrea; Blachowicz, Tomasz

2015-10-01

Simulations of mechanical or comfort properties of fibers, yarns and textile fabrics have been developed for a long time. In the course of increasing interest in smart textiles, models for conductive fabrics have also been developed. The magnetic properties of fibers or magnetic coatings, however, are almost exclusively being examined experimentally. This article thus describes different possibilities of micromagnetically modeling magnetic fibers or coatings. It gives an overview of calculation times for different dimensions of magnetic materials, indicating the limits due to available computer performance and shows the influence of these dimensions on the simulated magnetic properties for magnetic coatings on fibers and fabrics.

Mucoadhesive films containing chitosan-coated nanoparticles: a new strategy for buccal curcumin release.

PubMed

Mazzarino, Letícia; Borsali, Redouane; Lemos-Senna, Elenara

2014-11-01

Mucoadhesive films containing curcumin-loaded nanoparticles were developed, aiming to prolong the residence time of the dosage form in the oral cavity and to increase drug absorption through the buccal mucosa. Films were prepared by the casting method after incorporation of curcumin-loaded chitosan-coated polycaprolactone nanoparticles into plasticized chitosan solutions. Different molar masses of mucoadhesive polysaccharide chitosan and concentrations of plasticizer glycerol were used to optimize the preparation conditions. Films obtained using medium and high molar mass chitosan were found to be homogeneous and flexible. Curcumin-loaded nanoparticles were uniformly distributed on the film surface, as evidenced by atomic force microscopy and high-resolution field-emission gun scanning electron microscopy (FEG-SEM) images. Analyses of film cross sections using FEG-SEM demonstrate the presence of nanoparticles inside the films. In addition, films proved to have a good rate of hydration in simulated saliva solution, displaying a maximum swelling of around 80% and in vitro prolonged-controlled delivery of curcumin. These results indicate that the mucoadhesive films containing nanoparticles offer a promising approach for buccal delivery of curcumin, which may be particularly useful in the treatment of periodontal diseases that require a sustained drug delivery. © 2014 Wiley Periodicals, Inc. and the American Pharmacists Association.

3D Fiber Orientation Simulation for Plastic Injection Molding

NASA Astrophysics Data System (ADS)

Lin, Baojiu; Jin, Xiaoshi; Zheng, Rong; Costa, Franco S.; Fan, Zhiliang

2004-06-01

Glass fiber reinforced polymer is widely used in the products made using injection molding processing. The distribution of fiber orientation inside plastic parts has direct effects on quality of molded parts. Using computer simulation to predict fiber orientation distribution is one of most efficient ways to assist engineers to do warpage analysis and to find a good design solution to produce high quality plastic parts. Fiber orientation simulation software based on 2-1/2D (midplane /Dual domain mesh) techniques has been used in industry for a decade. However, the 2-1/2D technique is based on the planar Hele-Shaw approximation and it is not suitable when the geometry has complex three-dimensional features which cannot be well approximated by 2D shells. Recently, a full 3D simulation software for fiber orientation has been developed and integrated into Moldflow Plastics Insight 3D simulation software. The theory for this new 3D fiber orientation calculation module is described in this paper. Several examples are also presented to show the benefit in using 3D fiber orientation simulation.

Metal-Coated Optical Fibers for High Temperature Applications

NASA Technical Reports Server (NTRS)

Zeakes, Jason; Murphy, Kent; Claus, Richard; Greene, Jonathan; Tran, Tuan

1996-01-01

A DC magnetron sputtering system has been used to actively coat optical fibers with hermetic metal coatings during the fiber draw process. Thin films of Inconel 625 have been deposited on optical fibers and annealed in air at 2000 F. Scanning electron microscopy and Auger electron microscopy have been used to investigate the morphology and composition of the films prior to and following thermal cycling. Issues to be addressed include film adhesion, other coating materials, and a discussion of additional applications for this novel technology.

Metal matrix coated fiber composites and the methods of manufacturing such composites

DOEpatents

Weeks, Jr., Joseph K.; Gensse, Chantal

1993-01-01

A fiber coating which allows ceramic or metal fibers to be wetted by molten metals is disclosed. The coating inhibits degradation of the physical properties caused by chemical reaction between the fiber and the coating itself or between the fiber and the metal matrix. The fiber coating preferably includes at least a wetting layer, and in some applications, a wetting layer and a barrier layer between the fiber and the wetting layer. The wetting layer promotes fiber wetting by the metal matrix. The barrier layer inhibits fiber degradation. The fiber coating permits the fibers to be infiltrated with the metal matrix resulting in composites having unique properties not obtainable in pure materials.

Metal matrix coated fiber composites and the methods of manufacturing such composites

DOEpatents

Weeks, J.K. Jr.; Gensse, C.

1993-09-14

A fiber coating which allows ceramic or metal fibers to be wetted by molten metals is disclosed. The coating inhibits degradation of the physical properties caused by chemical reaction between the fiber and the coating itself or between the fiber and the metal matrix. The fiber coating preferably includes at least a wetting layer, and in some applications, a wetting layer and a barrier layer between the fiber and the wetting layer. The wetting layer promotes fiber wetting by the metal matrix. The barrier layer inhibits fiber degradation. The fiber coating permits the fibers to be infiltrated with the metal matrix resulting in composites having unique properties not obtainable in pure materials. 8 figures.

Plasmonic and silicon spherical nanoparticle antireflective coatings

NASA Astrophysics Data System (ADS)

Baryshnikova, K. V.; Petrov, M. I.; Babicheva, V. E.; Belov, P. A.

2016-03-01

Over the last decade, plasmonic antireflecting nanostructures have been extensively studied to be utilized in various optical and optoelectronic systems such as lenses, solar cells, photodetectors, and others. The growing interest to all-dielectric photonics as an alternative optical technology along with plasmonics motivates us to compare antireflective properties of plasmonic and all-dielectric nanoparticle coatings based on silver and crystalline silicon respectively. Our simulation results for spherical nanoparticles array on top of amorphous silicon show that both silicon and silver coatings demonstrate strong antireflective properties in the visible spectral range. For the first time, we show that zero reflectance from the structure with silicon coatings originates from the destructive interference of electric- and magnetic-dipole responses of nanoparticle array with the wave reflected from the substrate, and we refer to this reflection suppression as substrate-mediated Kerker effect. We theoretically compare the silicon and silver coating effectiveness for the thin-film photovoltaic applications. Silver nanoparticles can be more efficient, enabling up to 30% increase of the overall absorbance in semiconductor layer. Nevertheless, silicon coatings allow up to 64% absorbance increase in the narrow band spectral range because of the substrate-mediated Kerker effect, and band position can be effectively tuned by varying the nanoparticles sizes.

Plasmonic and silicon spherical nanoparticle antireflective coatings

PubMed Central

Baryshnikova, K. V.; Petrov, M. I.; Babicheva, V. E.; Belov, P. A.

2016-01-01

Over the last decade, plasmonic antireflecting nanostructures have been extensively studied to be utilized in various optical and optoelectronic systems such as lenses, solar cells, photodetectors, and others. The growing interest to all-dielectric photonics as an alternative optical technology along with plasmonics motivates us to compare antireflective properties of plasmonic and all-dielectric nanoparticle coatings based on silver and crystalline silicon respectively. Our simulation results for spherical nanoparticles array on top of amorphous silicon show that both silicon and silver coatings demonstrate strong antireflective properties in the visible spectral range. For the first time, we show that zero reflectance from the structure with silicon coatings originates from the destructive interference of electric- and magnetic-dipole responses of nanoparticle array with the wave reflected from the substrate, and we refer to this reflection suppression as substrate-mediated Kerker effect. We theoretically compare the silicon and silver coating effectiveness for the thin-film photovoltaic applications. Silver nanoparticles can be more efficient, enabling up to 30% increase of the overall absorbance in semiconductor layer. Nevertheless, silicon coatings allow up to 64% absorbance increase in the narrow band spectral range because of the substrate-mediated Kerker effect, and band position can be effectively tuned by varying the nanoparticles sizes. PMID:26926602

Nanoparticles based fiber optic SPR sensor

NASA Astrophysics Data System (ADS)

Shah, Kruti; Sharma, Navneet K.

2018-05-01

Localized surface plasmon resonance based fiber optic sensor using platinum nanoparticles is proposed and theoretically analyzed. Increase in thickness of nanoparticles layer increases the sensitivity of sensor. 50 nm thick platinum nanoparticles layer based sensor reveals highest sensitivity.

Gold-coated nanoparticles for use in biotechnology applications

DOEpatents

Berning, Douglas E [Los Alamos, NM; Kraus, Jr., Robert H.; Atcher, Robert W [Los Alamos, NM; Schmidt, Jurgen G [Los Alamos, NM

2009-07-07

A process of preparing gold-coated magnetic nanoparticles is disclosed and includes forming a suspension of magnetic nanoparticles within a suitable liquid, adding an amount of a reducible gold compound and a reducing agent to the suspension, and, maintaining the suspension for time sufficient to form gold-coated magnetic nanoparticles.

Gold-coated nanoparticles for use in biotechnology applications

DOEpatents

Berning, Douglas E [Los Alamos, NM; Kraus, Jr., Robert H.; Atcher, Robert W [Los Alamos, NM; Schmidt, Jurgen G [Los Alamos, NM

2007-06-05

A process of preparing gold-coated magnetic nanoparticles is disclosed and includes forming a suspension of magnetic nanoparticles within a suitable liquid, adding an amount of a reducible gold compound and a reducing agent to the suspension, and, maintaining the suspension for time sufficient to form gold-coated magnetic nanoparticles.

Multifunctional biocompatible coatings on magnetic nanoparticles

NASA Astrophysics Data System (ADS)

Bychkova, A. V.; Sorokina, O. N.; Rosenfeld, M. A.; Kovarski, A. L.

2012-11-01

Methods for coating formation on magnetic nanoparticles used in biology and medicine are considered. Key requirements to the coatings are formulated, namely, biocompatibility, stability, the possibility of attachment of pharmaceutical agents, and the absence of toxicity. The behaviour of nanoparticle/coating nanosystems in the body including penetration through cellular membranes and the excretion rates and routes is analyzed. Parameters characterizing the magnetic properties of these systems and their magnetic controllability are described. Factors limiting the applications of magnetically controlled nanosystems for targeted drug delivery are discussed. The bibliography includes 405 references.

Effect of BN coating on the strength of a mullite type fiber

NASA Astrophysics Data System (ADS)

Chawla, K. K.; Xu, Z. R.; Ha, J.-S.; Schmücker, M.; Schneider, H.

1997-09-01

Nextel 480 is a polycrystalline essentially mullite fiber (70 wt.-% Al2O3+28 wt.-% SiO2+2 wt.-% B2O3). Different thicknesses of BN were applied as coatings on this fiber. Optical, scanning electron, and transmission electron microscopy were used to characterize the microstructure of the coatings and fibers. The effects of coating and high temperature exposure on the fiber strength were investigated using two-parameter Weibull distribution. TEM examination showed that the BN coating has a turbostratic structure, with the basal planes lying predominantly parallel to the fiber surface. Such an orientation of coating is desirable for easy crack deflection and subsequent fiber pullout in a composite. The BN coated Nextel 480 fiber showed that Weibull mean strength increased first and then decreased with increasing coating thickness. This was due to the surface flaw healing effect of the coating (up to 0.3 μm) while in the case of thick BN coating (1 μm), the soft nature of the coating material had a more dominant effect and resulted in a decrease of the fiber strength. High temperature exposure of Nextel 480 resulted in grain growth, which led to a strength loss.

Surface modification and characterization of aramid fibers with hybrid coating

NASA Astrophysics Data System (ADS)

Chen, Jianrui; Zhu, Yaofeng; Ni, Qingqing; Fu, Yaqin; Fu, Xiang

2014-12-01

Aramid fibers were modified through solution dip-coating and interfacial in situ polymerization using a newly synthesized SiO2/shape memory polyurethane (SiO2/SMPU) hybrid. Fourier transform infrared and X-ray photoelectron spectroscopy indicated that the synthesized SiO2/SMPU hybrid successfully coated the fiber surface. The surface morphology of the aramid fibers and the single fiber tensile strength and interfacial shear strength (IFSS) of the composites were determined. The IFSS of the fiber coated with the hybrid improved by 45%, which benefited from a special "pizza-like" structure on the fiber surface.

Silica Coating of Nonsilicate Nanoparticles for Resin-Based Composite Materials

PubMed Central

Kaizer, M.R.; Almeida, J.R.; Gonçalves, A.P.R.; Zhang, Y.; Cava, S.S.; Moraes, R.R.

2016-01-01

This study was designed to develop and characterize a silica-coating method for crystalline nonsilicate ceramic nanoparticles (Al2O3, TiO2, and ZrO2). The hypothesis was that the coated nonsilicate nanoparticles would stably reinforce a polymeric matrix due to effective silanation. Silica coating was applied via a sol-gel method, with tetraethyl orthosilicate as a silica precursor, followed by heat treatment. The chemical and microstructural characteristics of the nanopowders were evaluated before and after silica coating through x-ray diffraction, BET (Brunauer-Emmett-Teller), energy-dispersive x-ray spectroscopy, field emission scanning electron microscopy, and transmission electron microscopy analyses. Coated and noncoated nanoparticles were silanated before preparation of hybrid composites, which contained glass microparticles in addition to the nanoparticles. The composites were mechanically tested in 4-point bending mode after aging (10,000 thermal cycles). Results of all chemical and microstructural analyses confirmed the successful obtaining of silica-coated nanoparticles. Two distinct aspects were observed depending on the type of nanoparticle tested: 1) formation of a silica shell on the surface of the particles and 2) nanoparticle clusters embedded into a silica matrix. The aged hybrid composites formulated with the coated nanoparticles showed improved flexural strength (10% to 30% higher) and work of fracture (35% to 40% higher) as compared with composites formulated with noncoated nanoparticles. The tested hypothesis was confirmed: silanated silica-coated nonsilicate nanoparticles yielded stable reinforcement of dimethacrylate polymeric matrix due to effective silanation. The silica-coating method presented here is a versatile and promising novel strategy for the use of crystalline nonsilicate ceramics as a reinforcing phase of polymeric composite biomaterials. PMID:27470069

Performance Stability of Silicone Oxide-Coated Plastic Parenteral Vials.

PubMed

Weikart, Christopher M; Pantano, Carlo G; Shallenberger, Jeff R

2017-01-01

A new packaging system was developed for parenteral pharmaceuticals that combines the best attributes of plastic and glass without their respective drawbacks. This technological advancement is based on the synergy between high-precision injection-molded plastics and plasma coating technology. The result is a shatter-resistant, optically clear, low-particulate, and chemically durable packaging system. The demand for this product is driven by the expanding market, regulatory constraints, and product recalls for injectable drugs and biologics packaged in traditional glass materials. It is shown that this new packaging system meets or exceeds the important performance characteristics of glass, especially in eliminating the glass delamination and breakage that has been observed in many products. The new packaging system is an engineered, multilayer, glass-coated plastic composite that provides a chemically stable contact surface and oxygen barrier performance that exceeds a 2 year shelf life requirement. Evaluation of the coating system characteristics and performance stability to chemical, temperature, and mechanical extremes are reported herein. LAY ABSTRACT: A new packaging system for parenteral pharmaceuticals was developed that combines the best attributes of plastic and glass without their respective drawbacks. This technological advancement is based on the synergy between high-precision injection-molded plastics and plasma coating technology. The result is a shatter-resistant, optically clear, low-particulate, and chemically durable packaging system. It is shown that this new packaging system meets or exceeds the important performance characteristics of glass, especially in eliminating the glass delamination and breakage that has been observed in many products. The new packaging system is an engineered, multilayer, glass-coated plastic composite that provides a chemically stable contact surface and oxygen barrier performance that exceeds a 2 year shelf life

Durability Characteristics Analysis of Plastic Worm Wheel with Glass Fiber Reinforced Polyamide.

PubMed

Kim, Gun-Hee; Lee, Jeong-Won; Seo, Tae-Il

2013-05-10

Plastic worm wheel is widely used in the vehicle manufacturing field because it is favorable for weight lightening, vibration and noise reduction, as well as corrosion resistance. However, it is very difficult for general plastics to secure the mechanical properties that are required for vehicle gears. If the plastic resin is reinforced by glass fiber in the fabrication process of plastic worm wheel, it is possible to achieve the mechanical properties of metallic material levels. In this study, the mechanical characteristic analysis of the glass-reinforced plastic worm wheel, according to the contents of glass fiber, is performed by analytic and experimental methods. In the case of the glass fiber-reinforced resin, the orientation and contents of glass fibers can influence the mechanical properties. For the characteristic prediction of plastic worm wheel, computer-aided engineering (CAE) analysis processes such as structural and injection molding analysis were executed with the polyamide resin reinforcement glass fiber (25 wt %, 50 wt %). The injection mold for fabricating the prototype plastic worm wheel was designed and made to reflect the CAE analysis results. Finally, the durability of prototype plastic worm wheel fabricated by the injection molding process was evaluated by the experimental method and the characteristics according to the glass fiber contents.

Durability Characteristics Analysis of Plastic Worm Wheel with Glass Fiber Reinforced Polyamide

PubMed Central

Kim, Gun-Hee; Lee, Jeong-Won; Seo, Tae-Il

2013-01-01

Plastic worm wheel is widely used in the vehicle manufacturing field because it is favorable for weight lightening, vibration and noise reduction, as well as corrosion resistance. However, it is very difficult for general plastics to secure the mechanical properties that are required for vehicle gears. If the plastic resin is reinforced by glass fiber in the fabrication process of plastic worm wheel, it is possible to achieve the mechanical properties of metallic material levels. In this study, the mechanical characteristic analysis of the glass-reinforced plastic worm wheel, according to the contents of glass fiber, is performed by analytic and experimental methods. In the case of the glass fiber-reinforced resin, the orientation and contents of glass fibers can influence the mechanical properties. For the characteristic prediction of plastic worm wheel, computer-aided engineering (CAE) analysis processes such as structural and injection molding analysis were executed with the polyamide resin reinforcement glass fiber (25 wt %, 50 wt %). The injection mold for fabricating the prototype plastic worm wheel was designed and made to reflect the CAE analysis results. Finally, the durability of prototype plastic worm wheel fabricated by the injection molding process was evaluated by the experimental method and the characteristics according to the glass fiber contents. PMID:28809248

Corrosion Prevention of Aluminum Nanoparticles by a Polyurethane Coating.

PubMed

Nishimura, Toshiyasu; Raman, Vedarajan

2014-06-19

In order to prevent corrosion, aluminum nanoparticles were coated with a polyurethane polymer. The coverage of the polyurethane polymer was controlled from 0 to 100%, which changed the corrosion rate of the nanoparticles quantitatively. The surface of the polymer coating was investigated by Transmission Electron Microscopy (TEM) and Atomic Force Microscopy (AFM), and the corrosion resistance of the nanoparticles was estimated by a wet/dry corrosion test on a Pt plate with a NaCl solution. From a TEM with EDAX analysis, the 10 mass% polymer coated Al particles in the synthesis were almost 100% covered on the surface by a polymer film of 10 nm thick. On the other hand, the 3 mass% polymer coated Al was almost 40% covered by a film. In the AFM, the potential around the Al particles had a relatively low value with the polymer coating, which indicated that the conductivity of the Al was isolated from the Pt plate by the polymer. Both the corrosion and H₂ evolution reaction rates were quantitatively reduced by the mass% of polymer coating. In the case of the 10 mass% coated sample, there was no corrosion of Al nanoparticles. This fact suggested that the electrochemical reaction was suppressed by the polymer coating. Moreover, the reaction rate of Al nanoparticles was suppressed in proportion to the coverage percentage of the coating. Thus, to conclude, it was found that the corrosion rate of Al nanoparticles could be quantitatively suppressed by the coverage percentage of the polymer coating.

Quantitation of Surface Coating on Nanoparticles Using Thermogravimetric Analysis.

PubMed

Dongargaonkar, Alpana A; Clogston, Jeffrey D

2018-01-01

Nanoparticles are critical components in nanomedicine and nanotherapeutic applications. Some nanoparticles, such as metallic nanoparticles, consist of a surface coating or surface modification to aid in its dispersion and stability. This surface coating may affect the behavior of nanoparticles in a biological environment, thus it is important to measure. Thermogravimetric analysis (TGA) can be used to determine the amount of coating on the surface of the nanoparticle. TGA experiments run under inert atmosphere can also be used to determine residual metal content present in the sample. In this chapter, the TGA technique and experimental method are described.

Formation of boron nitride coatings on silicon carbide fibers using trimethylborate vapor

NASA Astrophysics Data System (ADS)

Yuan, Mengjiao; Zhou, Tong; He, Jing; Chen, Lifu

2016-09-01

High quality boron nitride (BN) coatings have been grown on silicon carbide (SiC) fibers by carbothermal nitridation and at atmospheric pressure. SiC fibers were first treated in chlorine gas to form CDC (carbide-derived carbon) film on the fiber surface. The CDC-coated SiC fibers were then reacted with trimethylborate vapor and ammonia vapor at high temperature, forming BN coatings by carbothermal reduction. The FT-IR, XPS, XRD, SEM, TEM and AES were used to investigate the formation of the obtained coatings. It has been found that the obtained coatings are composed of phase mixture of h-BN and amorphous carbon, very uniform in thickness, have smooth surface and adhere well with the SiC fiber substrates. The BN-coated SiC fibers retain ∼80% strength of the as-received SiC fibers and show an obvious interfacial debonding and fiber pullout in the SiCf/SiOC composites. This method may be useful for the large scale production of high quality BN coating on silicon carbide fiber.

Surface spins disorder in uncoated and SiO2 coated maghemite nanoparticles

NASA Astrophysics Data System (ADS)

Zeb, F.; Nadeem, K.; Shah, S. Kamran Ali; Kamran, M.; Gul, I. Hussain; Ali, L.

2017-05-01

We studied the surface spins disorder in uncoated and silica (SiO2) coated maghemite (γ-Fe2O3) nanoparticles using temperature and time dependent magnetization. The average crystallite size for SiO2 coated and uncoated nanoparticles was about 12 and 29 nm, respectively. Scanning electron microscopy (SEM) showed that the nanoparticles are spherical in shape and well separated. Temperature scans of zero field cooled (ZFC)/field cooled (FC) magnetization measurements showed lower average blocking temperature (TB) for SiO2 coated maghemite nanoparticles as compared to uncoated nanoparticles. The saturation magnetization (Ms) of SiO2 coated maghemite nanoparticles was also lower than the uncoated nanoparticles and is attributed to smaller average crystallite size of SiO2 coated nanoparticles. For saturation magnetization vs. temperature data, Bloch's law (M(T)= M(0).(1- BTb)) was fitted well for both uncoated and SiO2 coated nanoparticles and yields: B =3×10-7 K-b, b=2.22 and B=0.0127 K-b, b=0.57 for uncoated and SiO2 coated nanoparticles, respectively. Higher value of B for SiO2 coated nanoparticles depicts decrease in exchange coupling due to enhanced surface spins disorder (broken surface bonds) as compared to uncoated nanoparticles. The Bloch's exponent b was decreased for SiO2 coated nanoparticles which is due to their smaller average crystallite size or finite size effects. Furthermore, a sharp increase of coercivity at low temperatures (<25 K) was observed for SiO2 coated nanoparticles which is also due to contribution of increased surface anisotropy or frozen surface spins in these smaller nanoparticles. The FC magnetic relaxation data was fitted to stretched exponential law which revealed slower magnetic relaxation for SiO2 coated nanoparticles. All these measurements revealed smaller average crystallite size and enhanced surface spins disorder in SiO2 coated nanoparticles than in uncoated γ-Fe2O3 nanoparticles.

Tensile Strength and Microstructural Characterization of Uncoated and Coated HPZ Ceramic Fibers

NASA Technical Reports Server (NTRS)

Bansal, Narottam P.; Wheeler, Donald R.; Dickerson, Robert M.

1996-01-01

Tensile strengths of as-received HPZ fiber and those surface coated with BN, BN/SiC, and BN/Si3N4 have been determined at room temperature using a two-parameter Weibull distribution. Nominally approx. 0.4 micron BN and 0.2 micron SiC or Si3N4 coatings were deposited on the fibers by chemical vapor deposition using a continuous reactor. The average tensile strength of uncoated HPZ fiber was 2.0 +/- 0.56 GPa (290 +/- 81 ksi) with a Weibull modulus of 4.1. For the BN coated fibers, the average strength and the Weibull modulus increased to 2.39 +/- 0.44 GPa (346 +/- 64 ksi) and 6.5, respectively. The HPZ/BN/SiC fibers showed an average strength of 2.0 +/- 0.32 GPa (290 +/- 47 ksi) and Weibull modulus of 7.3. Average strength of the fibers having a dual BN/Si3N4 surface coating degraded to 1.15 +/- 0.26 GPa (166 +/- 38 ksi) with a Weibull modulus of 5.3. The chemical composition and thickness of the fiber coatings were determined using scanning Auger analysis. Microstructural analysis of the fibers and the coatings was carried out by scanning electron microscopy and transmission electron microscopy. A microporous silica-rich layer approx. 200 nm thick is present on the as-received HPZ fiber surface. The BN coatings on the fibers are amorphous to partly turbostratic and contaminated with carbon and oxygen. Silicon carbide coating was crystalline whereas the silicon nitride coating was amorphous. The silicon carbide and silicon nitride coatings are non-stoichiometric, non-uniform, and granular. Within a fiber tow, the fibers on the outside had thicker and more granular coatings than those on the inside.

Mechanical, Chemical and Microstructural Characterization of Monazite-Coated Silicon Carbide Fibers

NASA Technical Reports Server (NTRS)

Bansal, N. P.; Wheeler, D. R.; Chen, Y. L.

2000-01-01

Tensile strengths of as-received Hi-Nicalon and Sylramic fibers and those having monazite surface coatings, deposited by atmospheric pressure chemical vapor deposition, were measured at room temperature and the Weibull statistical parameters determined. The average tensile strengths of uncoated Hi-Nicalon and Sylramic fibers were 3.19 +/- 0.73 and 2.78 +/- 0.53 GPa with a Weibull modulus of 5.41 and 5.52, respectively. The monazite-coated Hi-Nicalon and Sylramic fibers showed strength loss of approx. 10 and 15 percent, respectively, compared with the as-received fibers. The elemental compositions of the fibers and the coatings were analyzed using scanning Auger microprobe and energy dispersive X-ray spectroscopy. The LaPO4 coating on Hi-Nicalon fibers was approximately stoichiometric and about 50 nm thick. The coating on the Sylramic fibers extended to a depth of about 100 to 150 nm. The coating may have been stoichiometric LaPO4 in the first 30 to 40 nm of the layer. However, the surface roughness of Sylramic fiber made this profile somewhat difficult to interpret. Microstructural analyses of the fibers and the coatings were done by scanning electron microscopy, transmission electron microscopy, and selected area electron diffraction. Hi-Nicalon fiber consists of fine beta-SiC nanocrystals ranging in size from 1 to 30 mn embedded in an amorphous matrix. Sylramic is a polycrystalline stoichiometric silicon carbide fiber consisting of submicron beta-SiC crystallites ranging from 100 to 300 nm. Small amount of TiB2 nanocrystallites (approx. 50 nm) are also present. The LaPO4 coating on Hi-Nicalon fibers consisted of a chain of peanut shape particles having monazite-(La) structure. The coating on Sylramic fibers consisted of two layers. The inner layer was a chain of peanut shape particles having monazite-(La) structure. The outer layer was comprised of much smaller particles with a microcrystalline structure.

Nanoparticles from Degradation of Biodegradable Plastic Mulch

NASA Astrophysics Data System (ADS)

Flury, Markus; Sintim, Henry; Bary, Andy; English, Marie; Schaefer, Sean

2017-04-01

Plastic mulch films are commonly used in crop production. They provide multiple benefits, including control of weeds and insects, increase of soil and air temperature, reduction of evaporation, and prevention of soil erosion. The use of plastic mulch film in agriculture has great potential to increase food production and security. Plastic mulch films must be retrieved and disposed after usage. Biodegradable plastic mulch films, who can be tilled into the soil after usage offer great benefits as alternative to conventional polyethylene plastic. However, it has to be shown that the degradation of these mulches is complete and no micro- and nanoparticles are released during degradation. We conducted a field experiment with biodegradable mulches and tested mulch degradation. Mulch was removed from the field after the growing season and composted to facilitate degradation. We found that micro- and nanoparticles were released during degradation of the mulch films in compost. This raises concerns about degradation in soils as well.

Nanoparticle coated optical fibers for single microbubble generation

NASA Astrophysics Data System (ADS)

Pimentel-Domínguez, Reinher; Hernández-Cordero, Juan

2011-09-01

The study of bubbles and bubbly flows is important in various fields such as physics, chemistry, medicine, geophysics, and even the food industry. A wide variety of mechanical and acoustic techniques have been reported for bubble generation. Although a single bubble may be generated with these techniques, controlling the size and the mean lifetime of the bubble remains a difficult task. Most of the optical methods for generation of microbubbles involve high-power pulsed laser sources focused in absorbing media such as liquids or particle solutions. With these techniques, single micron-sized bubbles can be generated with typical mean lifetimes ranging from nano to microseconds. The main problem with these bubbles is their abrupt implosion: this produces a shock wave that can potentially produce damages on the surroundings. These effects have to be carefully controlled in biological applications and in laser surgery, but thus far, not many options are available to effectively control micron-size bubble growth. In this paper, we present a new technique to generate microbubbles in non-absorbing liquids. In contrast to previous reports, the proposed technique uses low-power and a CW radiation from a laser diode. The laser light is guided through an optical fiber whose output end has been coated with nanostructures. Upon immersing the tip of the fiber in ethanol or water, micron-size bubbles can be readily generated. With this technique, bubble growth can be controlled through adjustments on the laser power. We have obtained micron-sized bubbles with mean lifetimes in the range of seconds. Furthermore, the generated bubbles do not implode, as verified with a high-speed camera and flow visualization techniques.

Arrangement for connecting a fiber-reinforced plastic pipe to a stainless steel flange

DOEpatents

Allais, Arnaud [D-30625 Hannover, DE; Hoffmann, Ernst [D-30855 Langenhagen, DE

2008-02-05

Arrangement for connecting a fiber-reinforced plastic pipe (18) to a stainless steel flange (12, 16), in which the end of the fiber-reinforced plastic pipe (18) is accommodated in a ring-shaped groove (12a, 16a) in the flange (12, 16), the groove conforming to the dimensions of the fiber-reinforced plastic pipe (18), where the gap remaining between the end of the fiber-reinforced plastic pipe (18) and the ring-shaped groove (12a, 16a) is filled with a sealant (19).

Nitric Oxide-Releasing Silica Nanoparticle-Doped Polyurethane Electrospun Fibers

PubMed Central

Koh, Ahyeon; Carpenter, Alexis W.; Slomberg, Danielle L.; Schoenfisch, Mark H.

2013-01-01

Electrospun polyurethane fibers doped with nitric oxide (NO)-releasing silica particles are presented as novel macromolecular scaffolds with prolonged NO-release and high porosity. Fiber diameter (119–614 nm) and mechanical strength (1.7–34.5 MPa of modulus) were varied by altering polyurethane type and concentration, as well as the NO-releasing particle composition, size, and concentration. The resulting NO-releasing electrospun nanofibers exhibited ~83% porosity with flexible plastic or elastomeric behavior. The use of N-diazeniumdiolate- or S-nitrosothiol-modified particles yielded scaffolds exhibiting a wide range of NO release totals and durations (7.5 nmol mg−1–0.12 μmol mg−1 and 7 h to 2 weeks, respectively). The application of NO-releasing porous materials as coating for subcutaneous implants may improve tissue biocompatibility by mitigating the foreign body response and promoting cell integration. PMID:23915047

Coatings influencing thermal stress in photonic crystal fiber laser

NASA Astrophysics Data System (ADS)

Pang, Dongqing; Li, Yan; Li, Yao; Hu, Minglie

2018-06-01

We studied how coating materials influence the thermal stress in the fiber core for three holding methods by simulating the temperature distribution and the thermal stress distribution in the photonic-crystal fiber laser. The results show that coating materials strongly influence both the thermal stress in the fiber core and the stress differences caused by holding methods. On the basis of the results, a two-coating PCF was designed. This design reduces the stress differences caused by variant holding conditions to zero, then the stability of laser operations can be improved.

Comparison of cell uptake, biodistribution and tumor retention of folate-coated and PEG-coated gadolinium nanoparticles in tumor-bearing mice.

PubMed

Oyewumi, Moses O; Yokel, Robert A; Jay, Michael; Coakley, Tricia; Mumper, Russell J

2004-03-24

The purpose of these studies was to compare the cell uptake, biodistribution and tumor retention of folate-coated and PEG-coated gadolinium (Gd) nanoparticles. Gd is a potential agent for neutron capture therapy (NCT) of tumors. Gd nanoparticles were engineered from oil-in-water microemulsion templates. To obtain folate-coated nanoparticles, a folate ligand [folic acid chemically linked to distearoylphosphatidylethanolamine (DSPE) via a PEG spacer MW 3350] was included in nanoparticle preparations. Similarly, control nanoparticles were coated with DSPE-PEG-MW 3350 (PEG-coated). Nanoparticles were characterized based on size, size distribution, morphology, biocompatibility and tumor cell uptake. In vivo studies were carried out in KB (human nasopharyngeal carcinoma) tumor-bearing athymic mice. Biodistribution and tumor retention studies were carried out at pre-determined time intervals after injection of nanoparticles (10 mg/kg). Gd nanoparticles did not aggregate platelets or activate neutrophils. The retention of nanoparticles in the blood 8, 16 and 24 h post-injection was 60%, 13% and 11% of the injected dose (ID), respectively. A maximum Gd tumor localization of 33+/-7 microg Gd/g was achieved. Both folate-coated and PEG-coated nanoparticles had comparable tumor accumulation. However, the cell uptake and tumor retention of folate-coated nanoparticles was significantly enhanced over PEG-coated nanoparticles. Thus, the benefits of folate ligand coating were to facilitate tumor cell internalization and retention of Gd-nanoparticles in the tumor tissue. The engineered nanoparticles may have potential in tumor-targeted delivery of Gd thereby enhancing the therapeutic success of NCT.

Sol-gel antireflective coating on plastics

DOEpatents

Ashley, C.S.; Reed, S.T.

1988-01-26

An antireflection film made from reliquified sol-gel hydrolyzation, condensation polymeric reaction product of a silicon, alkoxides and/or metal alkoxides, or mixtures thereof. The film is particularly useful for coating plastics.

The toxicity of plastic nanoparticles to green algae as influenced by surface modification, medium hardness and cellular adsorption.

PubMed

Nolte, Tom M; Hartmann, Nanna B; Kleijn, J Mieke; Garnæs, Jørgen; van de Meent, Dik; Jan Hendriks, A; Baun, Anders

2017-02-01

To investigate processes possibly underlying accumulation and ecological effects of plastic nano-particles we have characterized their interaction with the cell wall of green algae. More specifically, we have investigated the influence of particle surface functionality and water hardness (Ca 2+ concentration) on particle adsorption to algae cell walls. Polystyrene nanoparticles with different functional groups (non-functionalized, -COOH and -NH 2 ) as well as coated (starch and PEG) gold nanoparticles were applied in these studies. Depletion measurements and atomic force microscopy (AFM) showed that adsorption of neutral and positively charged plastic nanoparticles onto the cell wall of P. subcapitata was stronger than that of negatively charged plastic particles. Results indicated that binding affinity is a function of both inter-particle and particle-cell wall interactions which are in turn influenced by the medium hardness and particle concentration. Physicochemical modelling using DLVO theory was used to interpret the experimental data, using also values for interfacial surface free energies. Our study shows that material properties and medium conditions play a crucial role in the rate and state of nanoparticle bio-adsorption for green algae. The results show that the toxicity of nanoparticles can be better described and assessed by using appropriate dose metrics including material properties, complexation/agglomeration behavior and cellular attachment and adsorption. The applied methodology provides an efficient and feasible approach for evaluating potential accumulation and hazardous effects of nanoparticles to algae caused by particle interactions with the algae cell walls. Copyright © 2016 Elsevier B.V. All rights reserved.

Polymer Coating of Carbon Nanotube Fibers for Electric Microcables

PubMed Central

Alvarez, Noe T.; Ochmann, Timothy; Kienzle, Nicholas; Ruff, Brad; Haase, Mark R.; Hopkins, Tracy; Pixley, Sarah; Mast, David; Schulz, Mark J.; Shanov, Vesselin

2014-01-01

Carbon nanotubes (CNTs) are considered the most promising candidates to replace Cu and Al in a large number of electrical, mechanical and thermal applications. Although most CNT industrial applications require macro and micro size CNT fiber assemblies, several techniques to make conducting CNT fibers, threads, yarns and ropes have been reported to this day, and improvement of their electrical and mechanical conductivity continues. Some electrical applications of these CNT conducting fibers require an insulating layer for electrical insulation and protection against mechanical tearing. Ideally, a flexible insulator such as hydrogenated nitrile butadiene rubber (HNBR) on the CNT fiber can allow fabrication of CNT coils that can be assembled into lightweight, corrosion resistant electrical motors and transformers. HNBR is a largely used commercial polymer that unlike other cable-coating polymers such as polyvinyl chloride (PVC), it provides unique continuous and uniform coating on the CNT fibers. The polymer coated/insulated CNT fibers have a 26.54 μm average diameter—which is approximately four times the diameter of a red blood cell—is produced by a simple dip-coating process. Our results confirm that HNBR in solution creates a few microns uniform insulation and mechanical protection over a CNT fiber that is used as the electrically conducting core. PMID:28344254

Polymer Coating of Carbon Nanotube Fibers for Electric Microcables.

PubMed

Alvarez, Noe T; Ochmann, Timothy; Kienzle, Nicholas; Ruff, Brad; Haase, Mark R; Hopkins, Tracy; Pixley, Sarah; Mast, David; Schulz, Mark J; Shanov, Vesselin

2014-11-04

Carbon nanotubes (CNTs) are considered the most promising candidates to replace Cu and Al in a large number of electrical, mechanical and thermal applications. Although most CNT industrial applications require macro and micro size CNT fiber assemblies, several techniques to make conducting CNT fibers, threads, yarns and ropes have been reported to this day, and improvement of their electrical and mechanical conductivity continues. Some electrical applications of these CNT conducting fibers require an insulating layer for electrical insulation and protection against mechanical tearing. Ideally, a flexible insulator such as hydrogenated nitrile butadiene rubber (HNBR) on the CNT fiber can allow fabrication of CNT coils that can be assembled into lightweight, corrosion resistant electrical motors and transformers. HNBR is a largely used commercial polymer that unlike other cable-coating polymers such as polyvinyl chloride (PVC), it provides unique continuous and uniform coating on the CNT fibers. The polymer coated/insulated CNT fibers have a 26.54 μm average diameter-which is approximately four times the diameter of a red blood cell-is produced by a simple dip-coating process. Our results confirm that HNBR in solution creates a few microns uniform insulation and mechanical protection over a CNT fiber that is used as the electrically conducting core.

Sol-gel antireflective coating on plastics

DOEpatents

Ashley, Carol S.; Reed, Scott T.

1990-01-01

An antireflection film made from a reliquified sol-gel hydrolyzation, condensation polymeric reaction product of a silicon, alkoxides and/or metal alkoxides, or mixtures thereof. The film is particularly useful for coating plastics.

The effect of irradiation process on the optical fiber coating

NASA Astrophysics Data System (ADS)

Wang, Zeyu; Xiao, Chun; Rong, Liang; Ji, Wei

2018-03-01

Protective fiber coating decides the mechanical strength of an optical fiber as well as its resistance against the influence of environment, especially in some special areas like irradiation atmospheres. According to the experiment in this paper, it was found that the tensile force and peeling force of resistant radiation optical fiber was improved because of the special optical fiber coating.

Polysaccharide-Coated Magnetic Nanoparticles for Imaging and Gene Therapy

PubMed Central

Uthaman, Saji; Cherukula, Kondareddy; Cho, Chong-Su; Park, In-Kyu

2015-01-01

Today, nanotechnology plays a vital role in biomedical applications, especially for the diagnosis and treatment of various diseases. Among the many different types of fabricated nanoparticles, magnetic metal oxide nanoparticles stand out as unique and useful tools for biomedical applications, because of their imaging characteristics and therapeutic properties such as drug and gene carriers. Polymer-coated magnetic particles are currently of particular interest to investigators in the fields of nanobiomedicine and fundamental biomaterials. Theranostic magnetic nanoparticles that are encapsulated or coated with polymers not only exhibit imaging properties in response to stimuli, but also can efficiently deliver various drugs and therapeutic genes. Even though a large number of polymer-coated magnetic nanoparticles have been fabricated over the last decade, most of these have only been used for imaging purposes. The focus of this review is on polysaccharide-coated magnetic nanoparticles used for imaging and gene delivery. PMID:26078971

Bidirectional optical coupler for plastic optical fibers.

PubMed

Sugita, Tatsuya; Abe, Tomiya; Hirano, Kouki; Itoh, Yuzo

2005-05-20

We have developed a low-loss bidirectional optical coupler for high-speed optical communication with plastic optical fibers (POFs). The coupler, which is fabricated by an injection molding method that uses poly (methyl methacrylate), has an antisymmetric tapered shape. We show that the coupler has low insertion and branching losses. The tapered shape of the receiving branch reduces beam diameter and increases detection efficiency coupling to a photodetector, whose area is smaller than that of the plastic optical fiber. The possibility of more than 15-m bidirectional transmission with a signaling bit rate up to 500 Mbits/s for simplex step-index POFs is demonstrated.

Metal-coated optical fibers for high temperature sensing applications

NASA Astrophysics Data System (ADS)

Fidelus, Janusz D.; Wysokiński, Karol; Stańczyk, Tomasz; Kołakowska, Agnieszka; Nasiłowski, Piotr; Lipiński, Stanisław; Tenderenda, Tadeusz; Nasiłowski, Tomasz

2017-10-01

An novel low-temperature method was used to enhance the corrosion resistance of copper or gold-coated optical fibers. A characterization of the elaborated materials and reports on selected studies such as cyclic temperature tests together with tensile tests is presented. Gold-coated optical fibers are proposed as a component of optical fiber sensors working in oxidizing atmospheres under temperatures exceeding 900 °C.

Effects of Fiber Coating Composition on Mechanical Behavior of Silicon Carbide Fiber-Reinforced Celsian Composites

NASA Technical Reports Server (NTRS)

Bansal, Narottam P.; Elderidge, Jeffrey I.

1998-01-01

Celsian matrix composites reinforced with Hi-Nicalon fibers, precoated with a dual layer of BN/SiC by chemical vapor deposition in two separate batches, were fabricated. Mechanical properties of the composites were measured in three-point flexure. Despite supposedly identical processing, the composite panels fabricated with fibers coated in two batches exhibited substantially different mechanical behavior. The first matrix cracking stresses (sigma(sub mc)) of the composites reinforced with fibers coated in batch 1 and batch 2 were 436 and 122 MPa, respectively. This large difference in sigma(sub mc) was attributed to differences in fiber sliding stresses(tau(sub friction)), 121.2+/-48.7 and 10.4+/-3.1 MPa, respectively, for the two composites as determined by the fiber push-in method. Such a large difference in values of tau(sub friction) for the two composites was found to be due to the difference in the compositions of the interface coatings. Scanning Auger microprobe analysis revealed the presence of carbon layers between the fiber and BN, and also between the BN and SiC coatings in the composite showing lower tau(sub friction). This resulted in lower sigma(sub mc) in agreement with the ACK theory. The ultimate strengths of the two composites, 904 and 759 MPa, depended mainly on the fiber volume fraction and were not significantly effected by tau(sub friction) values, as expected. The poor reproducibility of the fiber coating composition between the two batches was judged to be the primary source of the large differences in performance of the two composites.

Plastic optical fiber level measurement sensor based on side holes

NASA Astrophysics Data System (ADS)

Park, Young June; Shin, Jong-Dug; Park, Jaehee

2014-10-01

Plastic optical fiber level measurement sensor based on in-line side holes is investigated theoretically and experimentally. The sensor consists of a plastic optical fiber with in-line side holes spaced about 5 cm apart. The 0.9 diameter in-line side holes were fabricated by micro-drilling. An analytical expression of the sensor transmittance was obtained using a simple ray optics approach. The measurements of the sensor transmittance were performed with a 55 cm height Mass cylinder. Both results show that the sensor transmittance increases as the number of side holes filled with water increases. The research results indicate that the plastic optical fiber based on in-line side holes can be used for water level measurement.

Carbide coated fibers in graphites-aluminum composites. [(fabrication of metal matrix composites)

NASA Technical Reports Server (NTRS)

Imprescia, R. J.; Levinson, L. S.; Reiswig, R. D.; Wallace, T. C.; Williams, J. M.

1976-01-01

Research activities are described for a NASA-supported program at the Los Alamos Scientific Laboratory to develop graphite fiber-aluminum matrix composites. A chemical vapor deposition apparatus was constructed for continuously coating graphite fibers with TiC. As much as 150 meters of continuously coated fibers were produced. Deposition temperatures were varied from 1365 K to about 1750 K, and deposition time from 6 to 150 seconds. The 6 sec deposition time corresponded to a fiber feed rate of 2.54 m/min through the coater. Thin, uniform, adherent TiC coats, with thicknesses up to approximately 0.1 micrometer were produced on the individual fibers of Thornel 50 graphite yarns without affecting fiber strength. Although coat properties were fairly uniform throughout a given batch, more work is needed to improve the batch-to-batch reproducibility. Samples of TiC-coated Thornel 50 fibers were infiltrated with an aluminum alloy and hot-pressed in vacuum to produce small composite bars for flexure testing. Strengths as high as 90% of the rule-of-mixtures strength were achieved. Results of the examination of the fracture surfaces indicate that the bonding between the aluminum and the TiC-coated fibers is better than that achieved in a similar, commercially infiltrated material made with fibers having no observable surface coats. Several samples of Al-infiltrated, TiC-coated Thornel 50 graphite yarns, together with samples of the commercially infiltrated, uncoated fibers, were heated for 100 hours at temperatures near the alloy solidus. The TiC-coated samples appear to undergo less reaction than do the uncoated samples. Photomicrographs are shown.

Fracture detection in concrete by glass fiber cloth reinforced plastics

NASA Astrophysics Data System (ADS)

Shin, Soon-Gi; Lee, Sung-Riong

2006-04-01

Two types of carbon (carbon fiber and carbon powder) and a glass cloth were used as conductive phases and a reinforcing fiber, respectively, in polymer rods. The carbon powder was used for fabricating electrically conductive carbon powder-glass fiber reinforced plastic (CP-GFRP) rods. The carbon fiber tows and the CP-GFRP rods were adhered to mortar specimens using epoxy resin and glass fiber cloth. On bending, the electrical resistance of the carbon fiber tow attached to the mortar specimen increased greatly after crack generation, and that of the CP-GFRP rod increased after the early stages of deflection in the mortar. Therefore, the CP-GFRP rod is superior to the carbon fiber tow in detecting fractures. Also, by reinforcing with a glass fiber cloth reinforced plastic, the strength of the mortar specimens became more than twice as strong as that of the unreinforced mortar.

Gas-Phase Synthesis of Gold- and Silica-Coated Nanoparticles

NASA Astrophysics Data System (ADS)

Boies, Adam Meyer

2011-12-01

Composite nanoparticles consisting of separate core-shell materials are of interest for a variety of biomedical and industrial applications. By combining different materials at the nanoscale, particles can exhibit enhanced or multi-functional behavior such as plasmon resonance combined with superparamagnetism. Gas-phase nanoparticle synthesis processes are promising because they can continuously produce particles with high mass-yield rates. In this dissertation, new methods are investigated for producing gas-phase coatings of nanoparticles in an "assembly-line" fashion. Separate processes are developed to create coatings from silica and gold that can be used with a variety of core-particle chemistries. A photoinduced chemical vapor deposition (photo-CVD) method is used to produce silica coatings from tetraethyl orthosilicate (TEOS) on the surface of nanoparticles (diameter ˜5--70 nm). Tandem differential mobility analysis (TDMA) of the process demonstrates that particle coatings can be produced with controllable thicknesses (˜1--10 nm) by varying system parameters such as precursor flow rate. Electron microscopy and infrared spectroscopy confirm that the photo-CVD films uniformly coat the particles and that the coatings are silica. In order to describe the coating process a chemical mechanism is proposed that includes gas-phase, surface and photochemical reactions. A chemical kinetics model of the mechanism indicates that photo-CVD coating proceeds primarily through the photodecomposition of TEOS which removes ethyl groups, thus creating activated TEOS species. The activated TEOS then adsorbs onto the surface of the particle where a series of subsequent reactions remove the remaining ethyl groups to produce a silica film with an open site for further attachment. The model results show good agreement with the experimentally measured coating trends, where increased TEOS flow increases coating thickness and increased nitrogen flow decreases coating thickness. Gold

Miniaturization and automation of an internally cooled coated fiber device.

PubMed

Chen, Yong; Pawliszyn, Janusz

2006-07-15

The internally cooled coated fiber device was miniaturized to allow its direct introduction into a gas chromatography injector, while maintaining a reasonable lifetime of the septum. The device was robust, and its fiber, which was accommodated in an 18-gauge needle, was reproducibly used for more than 100 injections without any coating failure. The fiber temperature was controlled within 5 degrees C of the preset value by use of a temperature controller, a solenoid valve, and stainless steel tubings with different inner diameter. The device was mounted and used on the CTC CombiPAL autosampler with minor modifications, such as enlarging the hole of the needle guide of the autosampler and coupling the temperature control system of the device to the autosampler through a logic circuit. The device was validated with the back equilibration of hydrocarbons preloaded in the fiber in air. The automation of the internally cooled coated fiber device provided the feasibility of high throughput for the analysis of analytes in complex matrixes that required simultaneous heating of the sample matrixes and cooling of the fiber coating.

Solubility parameters of hypromellose acetate succinate and plasticization in dry coating procedures.

PubMed

Klar, Fabian; Urbanetz, Nora Anne

2016-10-01

Solubility parameters of HPMCAS have not yet been investigated intensively. On this account, total and three-dimensional solubility parameters of HPMCAS were determined by using different experimental as well as computational methods. In addition, solubility properties of HPMCAS in a huge number of solvents were tested and a Teas plot for HPMCAS was created. The total solubility parameter of about 24 MPa(0.5) was confirmed by various procedures and compared with values of plasticizers. Twenty common pharmaceutical plasticizers were evaluated in terms of their suitability for supporting film formation of HPMCAS under dry coating conditions. Therefore, glass transition temperatures of mixtures of polymer and plasticizers were inspected and film formation of potential ones was further investigated in dry coating of pellets. Contact angles of plasticizers on HPMCAS were determined in order to give a hint of achievable coating efficiencies in dry coating, but none was found to spread on HPMCAS. A few common substances, e.g. dimethyl phthalate, glycerol monocaprylate, and polyethylene glycol 400, enabled plasticization of HPMCAS; however, only triethyl citrate and triacetin were found to be suitable for use in dry coating. Addition of acetylated monoglycerides to triacetin increased coating efficiency, which was likewise previously demonstrated for triethyl citrate.

Metal-Coated Optical Fibers for High Temperature Applications

NASA Technical Reports Server (NTRS)

Zeakes, Jason; Murphy, Kent; Claus, Richard; Greene, Jonathan; Tran, Tuan

1996-01-01

This poster will highlight on-going research at the Virginia Tech Fiber & Electro-Optics Research Center (FEORC) in the area of thin films on optical fibers. Topics will include the sputter deposition of metals and metal; alloys onto optical fiber and fiber optic sensors for innovative applications. Specific information will be available on thin film fiber optic hydrogen sensors, corrosion sensors, and metal-coated optical fiber for high temperature aerospace applications.

Acute toxicity and pharmacokinetics of 13 nm-sized PEG-coated gold nanoparticles

DOE Office of Scientific and Technical Information (OSTI.GOV)

Cho, Wan-Seob; Cho, Minjung; Jeong, Jinyoung

2009-04-01

In general, gold nanoparticles are recognized as being as nontoxic. Still, there have been some reports on their toxicity, which has been shown to depend on the physical dimension, surface chemistry, and shape of the nanoparticles. In this study, we carry out an in vivo toxicity study using 13 nm-sized gold nanoparticles coated with PEG (MW 5000). In our findings the 13 nm sized PEG-coated gold nanoparticles were seen to induce acute inflammation and apoptosis in the liver. These nanoparticles were found to accumulate in the liver and spleen for up to 7 days after injection and to have longmore » blood circulation times. In addition, transmission electron microscopy showed that numerous cytoplasmic vesicles and lysosomes of liver Kupffer cells and spleen macrophages contained the PEG-coated gold nanoparticles. These findings of toxicity and kinetics of PEG-coated gold nanoparticles may have important clinical implications regarding the safety issue as PEG-coated gold nanoparticles are widely used in biomedical applications.« less

Conductive paper fabricated by layer-by-layer assembly of polyelectrolytes and ITO nanoparticles

NASA Astrophysics Data System (ADS)

Peng, C. Q.; Thio, Y. S.; Gerhardt, R. A.

2008-12-01

A new salt-free approach was developed for fabricating conductive paper by layer-by-layer (LBL) assembly of conductive indium tin oxide (ITO) nanoparticles and polyelectrolytes onto wood fibers. Subsequent to the coating procedure, the fibers were manufactured into conductive paper using traditional paper making methods. The wood fibers were first coated with polyethyleneimine (PEI) and then LBL assembled with poly(sodium 4-styrenesulfonate) (PSS) and ITO for several bilayers. The surface charge intensity of both the ITO nanoparticles and the coated wood fibers were evaluated by measuring the ζ-potential of the nanoparticles and short fibers, respectively. The ITO nanoparticles were found to preferentially aggregate on defects on the fiber surfaces and formed interconnected paths, which led to the formation of conductive percolation paths throughout the whole paper. With ten bilayer coatings, the as-made paper was made DC conductive, and its σdc was measured to be 5.2 × 10-6 S cm-1 in the in-plane (IP) direction, while the conductivity was 1.9 × 10-8 S cm-1 in the through-the-thickness (TT) direction. The percolation phenomena in these LBL-assembled ITO-coated paper fibers was evaluated using scanning electron microscopy (SEM), current atomic force microscopy (I-AFM), and impedance measurements. The AC electrical properties are reported for frequencies ranging from 0.01 Hz to 1 MHz. A clear transition from insulating to conducting behavior is observed in the AC conductivity.

Processing and Characterization of Nanoparticle Coatings for Quartz Crystal Microbalance Measurements

PubMed Central

Torrey, Jessica D.; Kirschling, Teresa L.; Greenlee, Lauren F.

2015-01-01

The quartz-crystal microbalance is a sensitive and versatile tool for measuring adsorption of a variety of compounds (e.g. small molecules, polymers, biomolecules, nanoparticles and cells) to surfaces. While the technique has traditionally been used for measuring adsorption to flat surfaces and thin ridged films, it can also be extended to study adsorption to nanoparticle surfaces when the nanoparticles are fixed to the crystal surface. The sensitivity and accuracy of the measurement depend on the users’ ability to reproducibly prepare a thin uniform nanoparticle coating. This study evaluated four coating techniques, including spin coating, spray coating, drop casting, and electrophoretic deposition, for two unique particle chemistries [nanoscale zero valent iron (nZVI) and titanium dioxide (TiO2)] to produce uniform and reproducible nanoparticle coatings for real-time quartz-crystal microbalance measurements. Uniform TiO2 coatings were produced from a 50 mg/mL methanol suspension via spin coating. Nanoscale zero-valent iron was best applied by spray coating a low concentration 1.0 mg/mL suspended in methanol. The application of multiple coatings, rather than an increase in the suspension concentration, was the best method to increase the mass of nanoparticles on the crystal surface while maintaining coating uniformity. An upper mass threshold was determined to be approximately 96 µg/cm2; above this mass, coatings no longer maintained their uniform rigid characteristic, and a low signal to noise ratio resulted in loss of measurable signal from crystal resonances above the fundamental. PMID:26958434

Practical Aspects of Access Network Indoor Extensions Using Multimode Glass and Plastic Optical Fibers

NASA Astrophysics Data System (ADS)

Keiser, Gerd; Liu, Hao-Yu; Lu, Shao-Hsi; Devi Pukhrambam, Puspa

2012-07-01

Low-cost multimode glass and plastic optical fibers are attractive for high-capacity indoor telecom networks. Many existing buildings already have glass multimode fibers installed for local area network applications. Future indoor applications will use combinations of glass multimode fibers with plastic optical fibers that have low losses in the 850-nm-1,310-nm range. This article examines real-world link losses when randomly interconnecting glass and plastic fiber segments having factory-installed connectors. Potential interconnection issues include large variations in connector losses among randomly selected fiber segments, asymmetric link losses in bidirectional links, and variations in bandwidths among different types of fibers.

Controlled assembly of nanoparticle structures: spherical and toroidal superlattices and nanoparticle-coated polymeric beads.

PubMed

Isojima, Tatsushi; Suh, Su Kyung; Vander Sande, John B; Hatton, T Alan

2009-07-21

The emulsion droplet solvent evaporation method has been used to prepare nanoclusters of monodisperse magnetite nanoparticles of varying morphologies depending on the temperature and rate of solvent evaporation and on the composition (solvent, presence of polymer, nanoparticle concentration, etc.) of the emulsion droplets. In the absence of a polymer, and with increasing solvent evaporation temperatures, the nanoparticles formed single- or multidomain crystalline superlattices, amorphous spherical aggregates, or toroidal clusters, as determined by the energetics and dynamics of the solvent evaporation process. When polymers that are incompatible with the nanoparticle coatings were included in the emulsion formulation, monolayer- and multilayer-coated polymer beads and partially coated Janus beads were prepared; the nanoparticles were expelled by the polymer as its concentration increased on evaporation of the solvent and accumulated on the surfaces of the beads in a well-ordered structure. The precise number of nanoparticle layers depended on the polymer/magnetic nanoparticle ratio in the oil droplet phase parent emulsion. The magnetic nanoparticle superstructures responded to the application of a modest magnetic field by forming regular chains with alignment of nonuniform structures (e.g., toroids and Janus beads) that are in accord with theoretical predictions and with observations in other systems.

Bioresponsive polymer coating on nanoparticles

NASA Astrophysics Data System (ADS)

Laemthong, Tunyaboon

Nanotechnology incorporated with molecular biology became a promising way to treat cancer. The size of nanoparticles enables them to overcome the side effects noticed in cancer treatment like chemotherapy and surgery. Various types and shapes of nanoparticles have been synthesized and used in drug delivery to tumor sites. However, one of problems of using these nanoparticles is the aggregation after injecting them into human body due to flow rate of bloodstream. The coagulation and aggregation will result in clogging blood vessel and lower therapeutic efficacy. In this thesis, a solution to the aggregation problem was proposed, which is coating biopolymer on nanoparticles (NPs). The experimental sections covered synthesis and characterization of breast cancer specific targeting drug-encapsulated NPs and biopolymer coating on the surface of Au-Fe3O4 NPs for thermal therapy. Furthermore, in vitro studies of these NPs with breast cancer cells were also included. The specific targeting anticancer drug-encapsulated NRs showed significant inhibition in BT-474 breast cancer cell growth. The Au-Fe3O4 NPs has a possibility to treat cancer cells using the thermal therapy approach.

Fogging technique used to coat magnesium with plastic

NASA Technical Reports Server (NTRS)

Mroz, T. S.

1967-01-01

Cleaning process and a fogging technique facilitate the application of a plastic coating to magnesium plates. The cleaning process removes general organic and inorganic surface impurities, oils and greases, and oxides and carbonates from the magnesium surfaces. The fogging technique produces a thin-filmlike coating in a clean room atmosphere.

Characteristic Analysis Light Intensity Sensor Based On Plastic Optical Fiber At Various Configuration

NASA Astrophysics Data System (ADS)

Arifin, A.; Lusiana; Yunus, Muhammad; Dewang, Syamsir

2018-03-01

This research discusses the light intensity sensor based on plastic optical fiber. This light intensity sensor is made of plastic optical fiber consisting of two types, namely which is cladding and without cladding. Plastic optical fiber used multi-mode step-index type made of polymethyl metacrylate (PMMA). The infrared LED emits light into the optical fiber of the plastic and is subsequently received by the phototransistor to be converted to an electric voltage. The sensor configuration is made with three models: straight configuration, U configuration and gamma configuration with cladding and without cladding. The measured light source uses a 30 Watt high power LED with a light intensity of 0 to 10 Klux. The measured light intensity will affect the propagation of light inside the optical fiber sensor. The greater the intensity of the measured light, the greater the output voltage that is read on the computer. The results showed that the best optical fiber sensor characteristics were obtained in U configuration. Sensors with U-configuration without cladding had the best sensitivity and resolution values of 0.0307 volts/Klux and 0.0326 Klux. The advantages of this measuring light intensity based on the plastic optical fiber instrument are simple, easy-to-make operational systems, low cost, high sensitivity and resolution.

Influence of BN fiber coatings on the interfacial structure of sapphire fiber reinforced NiAl composites

NASA Astrophysics Data System (ADS)

Reichert, K.; Wen, K.; Cremer, R.; Hu, W.; Neuschütz, D.; Gottstein, G.

2001-07-01

A new concept for a tailored fiber-matrix interface for sapphire fiber reinforced NiAl matrix composites is proposed, consisting of an initial hexagonal boron nitride (hBN) fiber coating. For this, single crystal Al 2O 3 fibers were coated with hBN by chemical vapor deposition (CVD). Following a comprehensive characterization of the CVD coating as to composition and structure by means of X-ray photoelectron spectroscopy (XPS) and grazing incidence X-ray diffraction (GIXRD), the fiber reinforced NiAl matrix composites were fabricated by diffusion bonding at 1400°C. The interfaces NiAl/BN and BN/Al 2O 3 were analyzed by scanning electron microscopy (SEM), analytical transmission electron microscopy (TEM), and selected area diffraction (SAD). An interfacial reaction between NiAl and hBN to form AlN was revealed using these analytical techniques.

A photochemical approach designed to improve the coating of nanoscale silver films onto food plastic wrappings intended to control bacterial hazards

NASA Astrophysics Data System (ADS)

Mustatea, Gabriel; Vidal, Loïc; Calinescu, Ioan; Dobre, Alina; Ionescu, Mariana; Balan, Lavinia

2015-01-01

Plasmonic silver film was directly generated on a variety of substrates through a facile and environmentally friendly method, which involves a UV-photoreduction process without any reducing or stabilizing agent and requiring no thermal step. Top-coated films of unprotected silver nanoparticles (3-11 nm) were generated from hydroalcoholic AgNO3 solution and directly on glass substrates or food packaging plastic wraps, low density polyethylene film, and polyvinyl chloride. The natural antibacterial activity of the material was evaluated. The correlation between silver migration and antimicrobial activity of silver-functionalized substrates against pure strains of gram-negative bacteria ( Escherichia coli) and gram-positive bacteria ( Staphylococcus aureus) was demonstrated. By way of illustration, food plastic wraps top-coated in this way exhibited a high antibacterial activity. The metal nanoparticle film obtained in this way was characterized and the influence of several parameters (fluence, exposure, silver nitrate concentration, and nature of the free radicals generator) on their formation was studied. Moreover, by shaping the actinic beam with an appropriate device, it is very easy to pattern the brown yellow silver nanofilm or to print messages in plain text.

Synthesis of superparamagnetic silica-coated magnetite nanoparticles for biomedical applications

NASA Astrophysics Data System (ADS)

Kaur, Navjot; Chudasama, Bhupendra

2015-05-01

Multifunctional superparamagnetic iron oxide nanoparticles (SPIONs) coated with silica are widely researched for biomedical applications such as magnetic resonance imaging, tissue repair, cell separation, hyperthermia, drug delivery, etc. In this article synthesis of magnetite (Fe3O4) nanoparticles and their coating with SiO2 is reported. Fe3O4 nanoparticles were synthesized by chemical co-precipitation and it was coated with silica by hydrolysis and condensation of tetraethylorthosilicate. XRD, FTIR, TEM and VSM techniques were used to characterize bare and coated nanoparticles. Results indicated that the average size of SPIONS was 8.4 nm. X-ray diffraction patterns of silica coated SPIONS were identical to that of SPIONS confirming the inner spinal structure of SPIONS. FTIR results confirmed the binding of silica with the magnetite and the formation of the silica shell around the magnetite core. Magnetic properties of SPIONS and silica coated SPIONS are determined by VSM. They are superparamagnetic. The major conclusion drawn from this study is that the synthesis route yields stable, non-aggregated magnetite-silica core-shell nanostructures with tailored morphology and excellent magnetic properties.

Study of high resistance inorganic coatings on graphite fibers. [for graphite-epoxy composite materials

NASA Technical Reports Server (NTRS)

Galasso, F. S.; Veltri, R. D.; Scola, D. A.

1979-01-01

Coatings made of boron, silicon carbide, silica, and silica-like materials were studied to determine their ability to increase resistance of graphite fibers. The most promising results were attained by chemical vapor depositing silicon carbide on graphite fiber followed by oxidation, and drawing graphite fiber through ethyl silicate followed by appropriate heat treatments. In the silicon carbide coating studies, no degradation of the graphite fibers was observed and resistance values as high as three orders of magnitude higher than that of the uncoated fiber was attained. The strength of a composite fabricated from the coated fiber had a strength which compared favorably with those of composites prepared from uncoated fiber. For the silica-like coated fiber prepared by drawing the graphite fiber through an ethyl silicate solution followed by heating, coated fiber resistances about an order of magnitude greater than that of the uncoated fiber were attained. Composites prepared using these fibers had flexural strengths comparable with those prepared using uncoated fibers, but the shear strengths were lower.

Silicon-doped boron nitride coated fibers in silicon melt infiltrated composites

DOEpatents

Corman, Gregory Scot; Luthra, Krishan Lal

2002-01-01

A fiber-reinforced silicon-silicon carbide matrix composite having improved oxidation resistance at high temperatures in dry or water-containing environments is produced. The invention also provides a method for protecting the reinforcing fibers in the silicon-silicon carbide matrix composites by coating the fibers with a silicon-doped boron nitride coating.

Silicon-doped boron nitride coated fibers in silicon melt infiltrated composites

DOEpatents

Corman, Gregory Scot; Luthra, Krishan Lal

1999-01-01

A fiber-reinforced silicon--silicon carbide matrix composite having improved oxidation resistance at high temperatures in dry or water-containing environments is produced. The invention also provides a method for protecting the reinforcing fibers in the silicon--silicon carbide matrix composites by coating the fibers with a silicon-doped boron nitride coating.

Development of fine-celled bio-fiber composite foams using physical blowing agents and nano-particles

NASA Astrophysics Data System (ADS)

Guo, Gangjian

As one of eco-friendly bio-fibers, wood-fiber has been incorporated in plastics to make wood-fiber/plastic composites (WPC) with an increased stiffness, durability and lowered cost. However, these improvements are usually accompanied by loss in the ductility and impact strength of the composites. These shortcomings can be significantly improved by incorporating a fine-cell foam structure in the composites. This thesis presents the development of the foaming technology for the manufacture of fine-cell WPC foams with environmentally benign physical blowing agents (PBAs), and focuses on the elucidation of the fundamental foaming mechanisms and the related issues involved. One critical issue comes from the volatiles evolved from the wood-fiber during high temperature processing. The volatiles, as a blowing agent, can contribute to the foaming process. However, they lead to gross deterioration of the cell structure of WPC foams. The presence of volatiles makes foaming of WPC "a poorly understood black art". With the use of PBAs, a strategy of lowering processing temperature becomes feasible, to suppress the generation of volatiles. A series of PBA-based experiments were designed using a statistical design of experiments (DOE) technique, and were performed to establish the relationship of processing and material variables with the structure of WPC foams. Fundamental foaming behaviors for two different PBAs and two different polymer systems were identified. WPC foams with a fine-cell morphology and a desired density were successfully obtained at the optimized conditions. Another limitation for the wider application of WPC is their flammability. Innovative use of a small amount of nano-clay in WPC significantly improved the flame-retarding property of WPC, and the key issue was to achieve a high degree of exfoliation of nano-particles in the polymer matrix, to achieve a desired flammability reduction. The synergistic effects of nano-particles in foaming of WPC were

High efficiency protein separation with organosilane assembled silica coated magnetic nanoparticles

NASA Astrophysics Data System (ADS)

Chang, Jeong Ho; Kang, Ki Ho; Choi, Jinsub; Jeong, Young Keun

2008-10-01

This work describes the development of high efficiency protein separation with functionalized organosilanes on the surface of silica coated magnetic nanoparticles. The magnetic nanoparticles were synthesized with average particle size of 9 nm and silica coated magnetic nanoparticles were obtained by controlling the coating thicknesses on magnetic nanoparticles. The silica coating thickness could be uniformly sized with a diameter of 10-40 nm by a sol-gel approach. The surface modification was performed with four kinds of functionalized organosilanes such as carboxyl, aldehyde, amine, and thiol groups. The protein separation work with organosilane assembled silica coated magnetic nanoparticles was achieved for model proteins such as bovine serum albumin (BSA) and lysozyme (LSZ) at different pH conditions. Among the various functionalities, the thiol group showed good separation efficiency due to the change of electrostatic interactions and protein conformational structure. The adsorption efficiency of BSA and LSZ was up to 74% and 90% corresponding pH 4.65 and pH 11.

Rare Earth Oxide Fluoride Nanoparticles And Hydrothermal Method For Forming Nanoparticles

DOEpatents

Fulton, John L.; Hoffmann, Markus M.

2003-12-23

A hydrothermal method for forming nanoparticles of a rare earth element, oxygen and fluorine has been discovered. Nanoparticles comprising a rare earth element, oxygen and fluorine are also described. These nanoparticles can exhibit excellent refractory properties as well as remarkable stability in hydrothermal conditions. The nanoparticles can exhibit excellent properties for numerous applications including fiber reinforcement of ceramic composites, catalyst supports, and corrosion resistant coatings for high-temperature aqueous solutions.

Rare earth oxide fluoride nanoparticles and hydrothermal method for forming nanoparticles

DOEpatents

Fulton, John L [Richland, WA; Hoffmann, Markus M [Richland, WA

2001-11-13

A hydrothermal method for forming nanoparticles of a rare earth element, oxygen and fluorine has been discovered. Nanoparticles comprising a rare earth element, oxygen and fluorine are also described. These nanoparticles can exhibit excellent refractory properties as well as remarkable stability in hydrothermal conditions. The nanoparticles can exhibit excellent properties for numerous applications including fiber reinforcement of ceramic composites, catalyst supports, and corrosion resistant coatings for high-temperature aqueous solutions.

Properties of carbon fibers with various coatings

NASA Technical Reports Server (NTRS)

Seegel, V.; Mcmahon, P.

1983-01-01

It is shown that all high modulus carbon fibers are durable with respect to thermal oxidation in air. Among the more widely used and economical materials with low modulus, Celion displays particularly good oxidative durability at high temperatures. This contrast to other materials is due to the low content of Natrium and Kalium in Celion carbon fibers. It is also noted that improved characteristics are attained in Celion carbon fiber/polyimide systems when fibers are used with high temperature resistant polyimide coatings.

Biodesulfurization of Dibenzothiophene by Microbial Cells Coated with Magnetite Nanoparticles

PubMed Central

Shan, GuoBin; Xing, JianMin; Zhang, HuaiYing; Liu, HuiZhou

2005-01-01

Microbial cells of Pseudomonas delafieldii were coated with magnetic Fe3O4 nanoparticles and then immobilized by external application of a magnetic field. Magnetic Fe3O4 nanoparticles were synthesized by a coprecipitation method followed by modification with ammonium oleate. The surface-modified Fe3O4 nanoparticles were monodispersed in an aqueous solution and did not precipitate in over 18 months. Using transmission electron microscopy (TEM), the average size of the magnetic particles was found to be in the range from 10 to 15 nm. TEM cross section analysis of the cells showed further that the Fe3O4 nanoparticles were for the most part strongly absorbed by the surfaces of the cells and coated the cells. The coated cells had distinct superparamagnetic properties. The magnetization (δs) was 8.39 emu · g−1. The coated cells not only had the same desulfurizing activity as free cells but could also be reused more than five times. Compared to cells immobilized on Celite, the cells coated with Fe3O4 nanoparticles had greater desulfurizing activity and operational stability. PMID:16085841

Localized coating removal using plastic media blasting

NASA Technical Reports Server (NTRS)

Novak, Howard L.; Wyckoff, Michael G.; Zook, Lee M.

1988-01-01

Steps taken to qualify the use of plastic media blasting for safely and effectively removing paint and other coatings from solid rocket booster aluminum structures are described. As a result of the effort, an improvement was made in the design of surface finishing equipment for processing flight hardware, in addition to a potentially patentable idea on improved plastic media composition. The general arrangement of the blast equipment and the nozzle configuration are presented.

Influence of pretreatment on the surface characteristics of PLLA fibers and subsequent hydroxyapatite coating.

PubMed

Peng, F; Olson, J R; Shaw, M T; Wei, M

2009-01-01

A fibrous precursor for bone repair composites was made by coating poly(L-lactide) (PLLA) fibers with hydroxyapatite (HA) using a biomimetic method. To enhance the bonding between the HA coating and the PLLA fiber, PLLA fibers were etched with either sodium hydroxide or sodium hypochlorite to generate carboxyl groups on fiber surfaces. The experiments were designed to determine the influence of etching on the fiber surface morphology and chemistry as well as the subsequent HA coating on the etched fiber surfaces. It was found that the etching pretreatment increased the roughness as well as the hydrophilicity of fibers, indicating that hydrolysis of PLLA chains had taken place on fiber surfaces. The etching pretreatment also promoted HA coating formation by introducing thicker coating on the surface of fibers with a longer etching time, a higher etching concentration, or with NaOCl as the etching agent. A mechanism of surface hydrolysis and oxidation of PLLA was proposed. (c) 2008 Wiley Periodicals, Inc.

Plasticized methylcellulose coating for reducing oil uptake in potato chips.

PubMed

Tavera-Quiroz, María José; Urriza, Marina; Pinotti, Adriana; Bertola, Nora

2012-05-01

As a result of consumers' health concerns and the trend towards healthier and low-fat food products, research has been undertaken to reduce the amount of fat absorbed in fried foods. This work focused on studying the efficacy of sorbitol and glycerol as plasticizers of methylcellulose coatings used to reduce oil uptake during the frying process of potato chips Changes in color, mechanical properties, water activity and lipid oxidation during storage were monitored. Also, an explanation regarding the different performances between both methylcellulose coatings with and without plasticizer was attained and techniques from the field of packaging films such as dynamic mechanical analyzer (DMA) and Fourier transform infrared spectroscopy were applied to analyze the behavior of coatings submitted to the frying operation. The application of a methylcellulose coating was an adequate choice to reduce oil absorption in fried potato chips. The most effective formulation was 10 g L(-1) methylcellulose with the addition of 7.5 g L(-1) sorbitol. With the incorporation of this formulation, oil absorption was reduced by 30%. Neither the sorbitol concentration nor the presence of the MC coating affected the puncture maximum force and color parameters L and a*. The results of the sensory analysis indicated that the panelists could not distinguish between the coated and uncoated potato chips. Methylcellulose-based coating plasticized with sorbitol could be an alternative for obtaining healthier potato chips. Copyright © 2011 Society of Chemical Industry.

An elasto-plastic solution for channel cracking of brittle coating on polymer substrate

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zhang, Chao; Chen, Fangliang; Gray, Matthew H.

In this study, an elasto-plastic channel-cracking model is presented to study the open-mode fracture of a thin layer brittle coating grown on a polymer substrate. A linear elastic shear interlayer is introduced to describe the stress transfer from the elasto-plastic substrate to the brittle coating, on basis of the shear-lag principle. The channel cracking behavior involves three stages: elastic, elasto-plastic and plastic stages, which are solved in a continuous manner based on the deformation status of the substrate. Explicit solutions are derived for the mutli-stage cracking process. Corresponding experimental tests for a titanium oxide (TiO 2) coating on a polymore » (ethylene terephthalate) substrate are conducted. The fracture toughness of the coating layer is estimated based on the crack spacing versus layer thickness relationship at certain strain levels. This method is found to be more reliable than the traditional methods using crack onset strain. Parametric studies of the fracture energy release rate for the coating and interfacial compliance of the thin film system are conducted, through which the effect of plastic deformation on the channel cracking behavior is studied extensively. The results indicate that the tangent modulus of the substrate controls the evolution curvature of crack spacing where a smaller tangent modulus corresponds to a slower saturation of crack spacing. The energy release rate also varies significantly with the properties of the interlayer. The study highlights the necessity of an elasto-plastic model for the thin film systems of brittle coating on a plastic substrate.« less

An elasto-plastic solution for channel cracking of brittle coating on polymer substrate

DOE PAGES

Zhang, Chao; Chen, Fangliang; Gray, Matthew H.; ...

2017-04-25

In this study, an elasto-plastic channel-cracking model is presented to study the open-mode fracture of a thin layer brittle coating grown on a polymer substrate. A linear elastic shear interlayer is introduced to describe the stress transfer from the elasto-plastic substrate to the brittle coating, on basis of the shear-lag principle. The channel cracking behavior involves three stages: elastic, elasto-plastic and plastic stages, which are solved in a continuous manner based on the deformation status of the substrate. Explicit solutions are derived for the mutli-stage cracking process. Corresponding experimental tests for a titanium oxide (TiO 2) coating on a polymore » (ethylene terephthalate) substrate are conducted. The fracture toughness of the coating layer is estimated based on the crack spacing versus layer thickness relationship at certain strain levels. This method is found to be more reliable than the traditional methods using crack onset strain. Parametric studies of the fracture energy release rate for the coating and interfacial compliance of the thin film system are conducted, through which the effect of plastic deformation on the channel cracking behavior is studied extensively. The results indicate that the tangent modulus of the substrate controls the evolution curvature of crack spacing where a smaller tangent modulus corresponds to a slower saturation of crack spacing. The energy release rate also varies significantly with the properties of the interlayer. The study highlights the necessity of an elasto-plastic model for the thin film systems of brittle coating on a plastic substrate.« less

Layer-by-layer polyelectrolyte coating for surface-enhanced Raman scattering on gold nanostars inside hollow core photonic crystal fibers

NASA Astrophysics Data System (ADS)

Burmistrova, Natalia A.; Bondarenko, Sergei D.; Bratashov, Daniil N.; Shuvalov, Andrei A.; Chibrova, Anastasiya A.; Khlebtsov, Boris N.; Skibina, Julia S.; Goryacheva, Irina Y.

2018-04-01

Photonic crystal fibers with hollow core (HC PCFs) are a specific class of optical fibers characterized by microstructure with periodic holes oriented along fiber. The combination of HC PCF with Raman spectroscopy for biosensors creation is attractive in the terms of the low sample volume, the possibility to increase the integration time without sample degradation and maintaining constant focus during experiments. Here we propose layer-by-layer polyelectrolyte coating of HC PCF inner surface in order to obtain charge-selective absorption of analyte, stabilization of Surface-Enhanced Raman scattering (SERS)-active gold nanoparticles. Distance between SERS hotspots and glass reduces nonlinear signals from glass, and increases signal-to-noise ratio of SERS spectra.

Synthesis of superparamagnetic silica-coated magnetite nanoparticles for biomedical applications

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kaur, Navjot, E-mail: navjot.dhindsa2989@gmail.com; Chudasama, Bhupendra, E-mail: bnchudasama@gmail.com

Multifunctional superparamagnetic iron oxide nanoparticles (SPIONs) coated with silica are widely researched for biomedical applications such as magnetic resonance imaging, tissue repair, cell separation, hyperthermia, drug delivery, etc. In this article synthesis of magnetite (Fe{sub 3}O{sub 4}) nanoparticles and their coating with SiO{sub 2} is reported. Fe{sub 3}O{sub 4} nanoparticles were synthesized by chemical co-precipitation and it was coated with silica by hydrolysis and condensation of tetraethylorthosilicate. XRD, FTIR, TEM and VSM techniques were used to characterize bare and coated nanoparticles. Results indicated that the average size of SPIONS was 8.4 nm. X-ray diffraction patterns of silica coated SPIONS were identicalmore » to that of SPIONS confirming the inner spinal structure of SPIONS. FTIR results confirmed the binding of silica with the magnetite and the formation of the silica shell around the magnetite core. Magnetic properties of SPIONS and silica coated SPIONS are determined by VSM. They are superparamagnetic. The major conclusion drawn from this study is that the synthesis route yields stable, non-aggregated magnetite-silica core-shell nanostructures with tailored morphology and excellent magnetic properties.« less

Synthesis of boron nitride coatings on quartz fibers: Thickness control and mechanism research

NASA Astrophysics Data System (ADS)

Zheng, Yu; Wang, Shubin

2011-10-01

Boron nitride (BN) coatings were successfully synthesized on quartz fibers by dip-coating in boric acid and urea solutions at 700 °C. The SEM micrographs indicated that the quartz fibers were fully covered by coatings with smooth surface. The XRD, FT-IR, XPS spectra and HR-TEM results showed that the composition of the coatings which combined closely with the quartz fibers was polycrystalline h-BN. By changing the dip circles, the coating thickness was well controlled. The thicknesses of samples dipped less than six circles increased linearly with dipping-circles; and the increment of coating thickness would slow down when the fibers were dipped 10 circles. After being dipped for 10 circles, the thickness was about 300 nm. The coating thickness was also established by calculation and the calculated results were consistent with the results measured by micrograph.

Pulsed operation of Tm-doped fiber lasers using piezoelectric-driven microbend applied to elliptical coating fibers

NASA Astrophysics Data System (ADS)

Sakata, H.; Kimpara, K.; Komori, K.; Tomiki, M.

2014-05-01

We report Q-switched pulse generation in Tm-doped fiber lasers by introducing piezoelectric-driven microbend into an elliptical coating fiber in a fiber ring resonator. Compared with the untreated circular fiber having a diameter of 240 μm, the elliptical coating fiber was flattened to have a major axis diameter of about 300 μm. We employed a pair of comblike plates attached on the piezoelectric actuators in order to bend the fiber from both sides. The output pulse power is improved by optimizing the tooth-width and spatial period of the comb-like plates, so that the elliptical coating fiber is easily bent and the propagation mode is efficiently coupled to radiation modes around λ = 1.9 μm. The Tm-doped fiber is pumped by a laser diode emitting at 1.63 μm and the pump light is introduced to the fiber ring resonator via the wavelength division multiplexing coupler. The emission spectra showed that the center oscillation wavelength was typically 1.92 μm. When the pump power was increased to 156 mW, the output pulse showed a peak power of 42.5 W with a pulse width of 1.06 μs. We expect that the in-fiber Q-switching technique will provide simple laser systems for environmental sensing and medical applications.

Thermal optical nonlinearity in photonic crystal fibers filled with nematic liquid crystals doped with gold nanoparticles

NASA Astrophysics Data System (ADS)

Lesiak, Piotr; Budaszewski, Daniel; Bednarska, Karolina; Wójcik, Michał; Sobotka, Piotr; Chychłowski, Miłosz; Woliński, Tomasz R.

2017-05-01

In this work we studied a newly reported class of nonlinear effects observed in 5CB liquid crystals doped with gold nanoparticles (GNPs). The size of the GNP was determined by direct TEM imaging and by X-ray scattering of the diluted NP solution. GNPs was coated by thiols with the ratio of mesogenic to n-alkyl thiols varying from 1:2 to 1:1. The research involved comparing properties of both undoped and doped 5CB (nematic LC) by infiltrating LC cell and microholes of the photonic crystal fiber (PCF) separately. In our experiment the PCF fiber type LMA-10 made by NKT Photonics as host material has been used.

CVD Fiber Coatings for Al2O3/NiAl Composites

NASA Technical Reports Server (NTRS)

Boss, Daniel E.

1995-01-01

While sapphire-fiber-reinforced nickel aluminide (Al2O3/NiAl) composites are an attractive candidate for high-temperature structures, the significant difference in the coefficient of thermal expansion between the NiAl matrix and the sapphire fiber creates substantial residual stresses in the composite. This study seeks to produce two fiber-coating systems with the potential to reduce the residual stresses in the sapphire/NiAl composite system. Chemical vapor deposition (CVD) was used to produce both the compensating and compliant-fiber coatings for use in sapphire/NiAl composites. A special reactor was designed and built to produce the FGM and to handle the toxic nickel precursors. This process was successfully used to produce 500-foot lengths of fiber with coating thicknesses of approximately 3 microns, 5 microns, and 10 microns.

Ultrathin fiber poly-3-hydroxybutyrate, modified by silicon carbide nanoparticles

NASA Astrophysics Data System (ADS)

Olkhov, A. A.; Krutikova, A. A.; Goldshtrakh, M. A.; Staroverova, O. V.; Iordanskii, A. L.; Ischenko, A. A.

2016-11-01

The article presents the results of studies the composite fibrous material based on poly-3-hydroxybutyrate (PHB) and nano-size silicon carbide obtained by the electrospinning method. Size distribution of the silicon carbide nanoparticles in the fiber was estimated by X-ray diffraction technique. It is shown that immobilization of the SiC nanoparticles to the PHB fibers contributes to obtaining essentially smaller diameter of fibers, high physical-mechanical characteristics and increasing resistance to degradation in comparison with the fibers of PHB.

Generation of drugs coated iron nanoparticles through high energy ball milling

DOE Office of Scientific and Technical Information (OSTI.GOV)

Radhika Devi, A.; Murty, B. S.; Chelvane, J. A.

The iron nanoparticles coated with oleic acid and drugs such as folic acid/Amoxicillin were synthesized by high energy ball milling and characterized by X-ray diffraction, Transmission electron microscope, zeta potential, dynamic light scattering, Fourier Transform Infra red (FT-IR) measurements, and thermo gravimetric analysis (TGA). FT-IR and TGA measurements show good adsorption of drugs on oleic acid coated nanoparticles. Magnetic measurements indicate that saturation magnetization is larger for amoxicillin coated particles compared to folic acid coated particles. The biocompatibility of the magnetic nanoparticles prepared was evaluated by in vitro cytotoxicity assay using L929 cells as model cells.

A Novel Method of Coating Orthodontic Archwires with Nanoparticles

PubMed Central

Syed, Shibli S; Kulkarni, Dinraj; Todkar, Rohit; Bagul, Ravikiran S; Parekh, Kreena; Bhujbal, Nikita

2015-01-01

Background: The major hazard to the orthodontic tooth movement is the friction developing at the bracket wire interface. In the past, there have been various attempts to reduce this friction. We believe that coating the commercially available orthodontic wires with nanoparticles can result in a successful reduction of this friction. The objective of this study is to develop a novel method of coating orthodontic archwires with nanoparticles. Materials and Methods: Stainless steel (Ormco, CA, USA), titanium molybdenum alloy (Ormco, CA, USA) and nickel-titanium (G and H Wire Company, USA) orthodontic wires with a rectangular cross-section dimension of 0.019”× 0.025”, were selected. The wires were later coated with a uniform and smooth nanoparticle film using 100 ml nanocremics. The coating procedure described in this article is a sol-gel thin film dip coating method. Results: The coating procedure was verified by comparing the surface topography of nanocoated archwires with the commercially available archwires in an environmental scanning electron microscope (ESEM). The ESEM images prove that the surface topography of the coated wires was found to be smoother with less surface deteriorations as compared to the commercially available wires. Conclusion: Commercially available orthodontic wires can be successfully coated using a novel method of sol-gel thin film dip coating method. PMID:26028899

Fire resistance properties of ceramic wool fiber reinforced intumescent coatings

NASA Astrophysics Data System (ADS)

Amir, N.; Othman, W. M. S. W.; Ahmad, F.

2015-07-01

This research studied the effects of varied weight percentage and length of ceramic wool fiber (CWF) reinforcement to fire retardant performance of epoxy-based intumescent coating. Ten formulations were developed using ammonium polyphosphate (APP), expandable graphite (EG), melamine (MEL) and boric acid (BA). The mixing was conducted in two stages; powdered materials were grinded in Rocklabs mortar grinder and epoxy-mixed using Caframo mixer at low speed mixing. The samples were applied on mild steel substrate and exposed to 500°C heat inside Carbolite electric furnace. The char expansion and its physical properties were observed. Scanning electron microscopy (SEM) analyses were conducted to inspect the fiber dispersion, fiber condition and the cell structure of both coatings and chars produced. Thermogravimetric analyses (TGA) were conducted to study the thermal properties of the coating such as degradation temperature and residual weight. Fire retardant performance was determined by measuring backside temperature of substrate in 1-hour, 1000°C Bunsen burner test according to UL 1709 fire regime. The results showed that intumescent coating reinforced with CWF produced better fire resistance performance. When compared to unreinforced coating, formulation S6-15 significantly reduced steel temperature at approximately 34.7% to around 175°C. However, higher fiber weight percentage had slightly decreased fire retardant performance of the coating.

Thermoplastic coating of carbon fibers

NASA Technical Reports Server (NTRS)

Edie, D. D.; Lickfield, G. C.; Drews, M. J.; Ellison, M. S.; Allen, L. E.; Mccollum, J. R.; Thomas, H. L.

1988-01-01

Now that quantities of prepreg were made on the thermoplastic coating line, they are being formed into both textile preform structures and directly into composite samples. The textile preforms include both woven and knitted structures which will be thermoformed into a finished part. In order to determine if the matrix resin is properly adhering to the fibers or if voids are being formed in the coating process, the tensile strength and modulus of these samples will be tested. The matrix uniformity of matrix distribution in these samples is also being determined using an image analyzer.

Magnesium coated phosphate glass fibers for unidirectional reinforcement of polycaprolactone composites.

PubMed

Liu, Xiaoling; Grant, David M; Palmer, Graham; Parsons, Andrew J; Rudd, Chris D; Ahmed, Ifty

2015-10-01

Bioresorbable composites have shown much potential for bone repair applications, as they have the ability to degrade completely over time and their degradation and mechanical properties can be tailored to suit the end application. In this study, phosphate glass fiber (from the system 45% P2 O5-16% CaO-24% MgO-11% Na2 O-4% Fe2 O3 (given in mol%)) were used to reinforce polycaprolactone (PCL) with approximately 20% fiber volume fraction. The glass fiber surfaces were coated with magnesium (Mg) through magnetron sputtering to improve the fiber-matrix interfacial properties. The Mg coating provided a rough fiber surface (roughness (Ra) of about 44nm). Both noncoated and Mg-coated fiber-reinforced composites were assessed. The water uptake and mass loss properties for the composites were assessed in phosphate-buffered saline (PBS) at 37°C for up to 28 days, and ion release profiles were also investigated in both water and PBS media. Inhibition of media influx was observed for the Mg-coated composites. The composite mechanical properties were characterized on the basis of both tensile and flexural tests and their retention in PBS media at 37°C was also investigated. A higher retention of the mechanical properties was observed for the Mg-coated composites over the 28 days degradation period. © 2014 Wiley Periodicals, Inc.

Room-temperature aqueous plasma electrolyzing Al2O3 nano-coating on carbon fiber

NASA Astrophysics Data System (ADS)

Zhang, Yuping; Meng, Yang; Shen, Yonghua; Chen, Weiwei; Cheng, Huanwu; Wang, Lu

2017-10-01

A novel room-temperature aqueous plasma electrolysis technique has been developed in order to prepared Al2O3 nano-coating on each fiber within a carbon fiber bundle. The microstructure and formation mechanism of the Al2O3 nano-coating were systematically investigated. The oxidation resistance and tensile strength of the Al2O3-coated carbon fiber was measured at elevated temperatures. It showed that the dense Al2O3 nano-coating was relatively uniformly deposited with 80-120 nm in thickness. The Al2O3 nano-coating effectively protected the carbon fiber, evidenced by the slower oxidation rate and significant increase of the burn-out temperature from 800 °C to 950 °C. Although the bare carbon fiber remained ∼25 wt.% after oxidation at 700 °C for 20 min, a full destruction was observed, evidenced by the ∼0 GPa of the tensile strength, compared to ∼1.3 GPa of the Al2O3-coated carbon fiber due to the effective protection from the Al2O3 nano-coating. The formation mechanism of the Al2O3 nano-coating on carbon fiber was schematically established mainly based on the physic-chemical effect in the cathodic plasma arc zone.

Elasto-optics in double-coated optical fibers induced by axial strain and hydrostatic pressure.

PubMed

Yang, Yu-Ching; Lee, Haw-Long; Chou, Huann-Ming

2002-04-01

Stresses, microbending loss, and refractive-index changes induced simultaneously by axial strain and hydrostatic pressure in double-coated optical fibers are analyzed. The lateral pressure and normal stresses in the optical fiber, primary coating, and secondary coating are derived. Also presented are the microbending loss and refractive-index changes in the glass fiber. The normal stresses are affected by axial strain, hydrostatic pressure, material properties, and thickness of the primary and secondary coatings. It is found that microbending loss decreases with increasing thickness, the Young's modulus, and the Poisson's ratio of the secondary coating but increases with the increasing Young's modulus and Poisson's ratio of the primary coating. Similarly, changes in refractive index in the glass fiber decrease with the increasing Young's modulus and Poisson's ratio of the secondary coating but increase with the increasing Young's modulus and Poisson's ratio of the primary coating. Therefore, to minimize microbending loss induced simultaneously by axial strain and hydrostatic pressure in the glass fiber, the polymeric coatings should be suitably selected. An optimal design procedure is also indicated.

Sonochemical coating of textile fabrics with antibacterial nanoparticles

NASA Astrophysics Data System (ADS)

Beddow, Jamie; Singh, Gagandeep; Blanes, María; Molla, Korina; Perelshtein, Ilana; Gedanken, Aharon; Joyce, Eadaoin; Mason, Timothy

2012-05-01

The high incidence of hospital-acquired infections places a huge financial burden on our healthcare systems. These infections are also responsible for many millions of deaths each year. Antibacterial fabrics for use in medical textiles, such as hospital uniforms, bedding and wound dressings, can provide a useful weapon in the on-going fight against these infections. The aim of this EU funded Framework 7 project is to develop a pilot line sonochemical coating machine for the production of antibacterial fabrics. The sonochemical coating technology under development is based on a lab scale process that was developed at Bar-Ilan University (BIU). It involves two processes that are driven by acoustic cavitation; the in situ generation of the metal oxide (MO) nanoparticles and the simultaneous high velocity propulsion of these nanoparticles onto a fabric leading to impregnation. Here we report on a comparison of 2 different MO nanoparticle coatings, ZnO and CuO, that were sonochemically applied on to a plain cotton fabric. Both of these coatings were prepared by BIU. In this work, the antibacterial efficacy of the coated fabrics was quantitatively assessed using the absorption method from BS EN ISO 20743:2007. Both types of metal oxide nanoparticle displayed antibacterial activity against all of the test bacteria with particularly high levels of bacterial reduction observed with the CuO coating. The results presented here are from an EU Framework 7 funded project (SONO, EU Project Number: 228730). The project is a collaboration between 17 partner organizations from 10 different European countries. Further details can be found on the project website at: www.fp7-sono.eu.

Sheddable Coatings for Long-Circulating Nanoparticles

PubMed Central

Romberg, Birgit; Hennink, Wim E.

2007-01-01

Nanoparticles, such as liposomes, polymeric micelles, lipoplexes and polyplexes are frequently studied as targeted drug carrier systems. The ability of these particles to circulate in the bloodstream for a prolonged period of time is often a prerequisite for successful targeted delivery. To achieve this, hydrophilic ‘stealth’ polymers, such as poly(ethylene glycol) (PEG), are used as coating materials. Such polymers shield the particle surface and thereby reduce opsonization by blood proteins and uptake by macrophages of the mononuclear phagocyte system. Yet, after localizing in the pathological site, nanoparticles should deliver their contents in an efficient manner to achieve a sufficient therapeutic response. The polymer coating, however, may hinder drug release and target cell interaction and can therefore be an obstacle in the realization of the therapeutic response. Attempts have been made to enhance the therapeutic efficacy of sterically stabilized nanoparticles by means of shedding, i.e. a loss of the coating after arrival at the target site. Such an ‘unmasking’ process may facilitate drug release and/or target cell interaction processes. This review presents an overview of the literature regarding different shedding strategies that have been investigated for the preparation of sterically stabilized nanoparticulates. Detach mechanisms and stimuli that have been used are described. PMID:17551809

IR fiber temperature sensing system

NASA Technical Reports Server (NTRS)

Tran, D. C.; Levin, K. H.; Mossadegh, R.; Koontz, Steve

1988-01-01

Infrared fiber optic pyrometry has become a practical reality using improved strength fluoride glass fibers. The addition of a plastic coating and rugged cabling allows the fibers to be used in the field. A detailed theoretical model of the infrared fiber optic pyrometer (non-contact or radiative thermometer) has been derived and compared with data produced by a prototype fluoride glass fiber radiative thermometer. Excellent agreement was obtained between theory and experiment over a temperature range of 30 to 700 C.

Clad-pumped Er-nanoparticle-doped fiber laser (Conference Presentation)

NASA Astrophysics Data System (ADS)

Baker, Colin C.; Friebele, E. Joseph; Rhonehouse, Daniel L.; Marcheschi, Barbara A.; Peele, John R.; Kim, Woohong; Sanghera, Jasbinder S.; Zhang, Jun; Chen, Youming; Pattnaik, Radha K.; Dubinskii, Mark

2017-03-01

Erbium-doped fiber lasers are attractive for directed energy weapons applications because they operate in a wavelength region that is both eye-safer and a window of high atmospheric transmission. For these applications a clad-pumped design is desirable, but the Er absorption must be high because of the areal dilution of the doped core vs. the pump cladding. High Er concentrations typically lead to Er ion clustering, resulting in quenching and upconversion. Nanoparticle (NP) doping of the core overcomes these problems by physically surrounding the Er ions with a cage of Al and O in the NP, which keeps them separated to minimize excited state energy transfer. A significant issue is obtaining high Er concentrations without the NP agglomeration that degrades the optical properties of the fiber core. We have developed the process for synthesizing stable Er-NP suspension which have been used to fabricate EDFs with Er concentrations >90 dB/m at 1532 nm. Matched clad fibers have been evaluated in a core-pumped MOPA with pump and signal wavelengths of 1475 and 1560 nm, respectively, and efficiencies of 72% with respect to absorbed pump have been obtained. We have fabricated both NP- and solution-doped double clad fibers, which have been measured in a clad-pumped laser testbed using a 1532 nm pump. The 1595 nm laser efficiency of the NP-doped fiber was 47.7%, which is high enough for what is believed to be the first laser experiment with the cladding pumped, NP-doped fiber. Further improvements are likely with a shaped cladding and new low-index polymer coatings with lower absorption in the 1500 - 1600 nm range.

Amine-functionalized MIL-53(Al)-coated stainless steel fiber for efficient solid-phase microextraction of synthetic musks and organochlorine pesticides in water samples.

PubMed

Xie, Lijun; Liu, Shuqin; Han, Zhubing; Jiang, Ruifen; Zhu, Fang; Xu, Weiqin; Su, Chengyong; Ouyang, Gangfeng

2017-09-01

The fiber coating is the key part of the solid-phase microextraction (SPME) technique, and it determines the sensitivity, selectivity, and repeatability of the analytical method. In this work, amine (NH 2 )-functionalized material of Institute Lavoisier (MIL)-53(Al) nanoparticles were successfully synthesized, characterized, and applied as the SPME fiber coating for efficient sample pretreatment owing to their unique structures and excellent adsorption properties. Under optimized conditions, the NH 2 -MIL-53(Al)-coated fiber showed good precision, low limits of detection (LODs) [0.025-0.83 ng L -1 for synthetic musks (SMs) and 0.051-0.97 ng L -1 for organochlorine pesticides (OCPs)], and good linearity. Experimental results showed that the NH 2 -MIL-53(Al) SPME coating was solvent resistant and thermostable. In addition, the extraction efficiencies of the NH 2 -MIL-53(Al) coating for SMs and OCPs were higher than those of commercially available SPME fiber coatings such as polydimethylsiloxane, polydimethylsiloxane-divinylbenzene, and polyacrylate. The reasons may be that the analytes are adsorbed on NH 2 -MIL-53(Al) primarily through π-π interactions, electron donor-electron acceptor interactions, and hydrogen bonds between the analytes and organic linkers of the material. Direct immersion (DI) SPME-gas chromatography-mass spectrometry methods based on NH 2 -MIL-53(Al) were successfully applied for the analysis of tap and river water samples. The recoveries were 80.3-115% for SMs and 77.4-117% for OCPs. These results indicate that the NH 2 -MIL-53(Al) coating may be a promising alternative to SPME coatings for the enrichment of SMs and OCPs.

Interactions of DNA coated upconversion nanoparticles with 2D materials

NASA Astrophysics Data System (ADS)

Giust, Davide; Lucío, María. Isabel; Muskens, Otto L.; Kanaras, Antonios G.

2018-02-01

In this work we investigated the nature of quenching between different types of 2D materials (WS2, MoS2 and graphene oxide) and oligonucleotide coated-upconversion nanoparticles. This study contributes towards the efficient design of biosensors based on 2D materials and DNA-coated upconversion nanoparticles.

Glass frits coated with silver nanoparticles for silicon solar cells

NASA Astrophysics Data System (ADS)

Li, Yingfen; Gan, Weiping; Zhou, Jian; Li, Biyuan

2015-06-01

Glass frits coated with silver nanoparticles were prepared by electroless plating. Gum Arabic (GA) was used as the activating agent of glass frits without the assistance of stannous chloride or palladium chloride. The silver-coated glass frits prepared with different GA dosages were characterized by X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), and thermogravimetric analysis (TGA). The characterization results indicated that silver-coated glass frits had the structures of both glass and silver. Spherical silver nanoparticles were distributed on the glass frits evenly. The density and particle size of silver nanoparticles on the glass frits can be controlled by adjusting the GA dosage. The silver-coated glass frits were applied to silver pastes to act as both the densification promoter and silver crystallite formation aid in the silver electrodes. The prepared silver-coated glass frits can improve the photovoltaic performances of solar cells.

Effects of coating spherical iron oxide nanoparticles

DOE Office of Scientific and Technical Information (OSTI.GOV)

Milosevic, Irena; Motte, Laurence; Aoun, Bachir

2017-01-01

We investigate the effect of several coatings applied in biomedical applications to iron oxide nanoparticles on the size, structure and composition of the particles. The four structural techniques employed - TEM, DLS, VSM, SAXS and EXAFS - show no significant effects of the coatings on the spherical shape of the bare nanoparticles, the average sizes or the local order around the Fe atoms. The NPs coated with hydroxylmethylene bisphosphonate or catechol have a lower proportion of magnetite than the bare and citrated ones, raising the question whether the former are responsible for increasing the valence state of the oxide onmore » the NP surfaces and lowering the overall proportion of magnetite in the particles. VSM measurements show that these two coatings lead to a slightly higher saturation magnetization than the citrate. This article is part of a Special Issue entitled "Science for Life" Guest Editor: Dr. Austen Angell, Dr. Salvatore Magazu and Dr. Federica Migliardo.« less

Gas chromatographic detection of some nitro explosive compounds in soil samples after solid-phase microextraction with carbon ceramic copper nanoparticle fibers.

PubMed

Farhadi, Khalil; Bochani, Shayesteh; Hatami, Mehdi; Molaei, Rahim; Pirkharrati, Hossein

2014-07-01

In this research, a new solid-phase microextraction fiber based on carbon ceramic composites with copper nanoparticles followed by gas chromatography with flame ionization detection was applied for the extraction and determination of some nitro explosive compounds in soil samples. The proposed method provides an overview of trends related to synthesis of solid-phase microextraction sorbents and their applications in preconcentration and determination of nitro explosives. The sorbents were prepared by mixing of copper nanoparticles with a ceramic composite produced by mixture of methyltrimethoxysilane, graphite, methanol, and hydrochloric acid. The prepared sorbents were coated on copper wires by dip-coating method. The prepared nanocomposites were evaluated statistically and provided better limits of detection than the pure carbon ceramic. The limit of detection of the proposed method was 0.6 μg/g with a linear response over the concentration range of 2-160 μg/g and square of correlation coefficient >0.992. The new proposed fiber has been demonstrated to be a suitable, inexpensive, and sensitive candidate for extraction of nitro explosive compounds in contaminated soil samples. The constructed fiber can be used more than 100 times without the need for surface generation. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Microstructural, Chemical and Mechanical Characterization of Polymer-Derived Hi-Nicalon Fibers with Surface Coatings

NASA Technical Reports Server (NTRS)

Bansal, Narottam P.; Chen, Yuan L.

1998-01-01

Room temperature tensile strengths of as-received Hi-Nicalon fibers and those having BN/SiC, p-BN/SiC, and p-B(Si)N/SiC surface coatings, deposited by chemical vapor deposition, were measured using an average fiber diameter of 13.5 microns. The Weibull statistical parameters were determined for each fiber. The average tensile strength of uncoated Hi-Nicalon on was 3.19 +/- 0.73 GPa with a Weibull modulus of 5.41. Strength of fibers coated with BN/SiC did not change. However, coat with p-BN/SiC and p-B(Si)N/SiC surface layers showed strength loss of approx. 10 and 35 percent, respectively, compared with as-received fibers. The elemental compositions of the fibers and the coatings were analyzed using scanning Auger microprobe and energy dispersive x-ray spectroscopy. The BN coating was contaminated with a large concentration of carbon and some oxygen. In contrast, p-BN, p-B(Si)N, and SiC coatings did not show any contamination. Microstructural analyses of the fibers and the coatings were done by scanning electron microscopy (SEM), transmission electron microscopy (TEM), and selected area electron diffraction. Hi-Nicalon fiber consists of the P-SIC nanocrystals ranging in size from 1 to 30 nm embedded in an amorphous matrix. TEM analysis of the BN coating revealed four distinct layers with turbostatic structure. The p-BN layer was turbostratic and showed considerable preferred orientation. The p-B(Si)N was glassy and the silicon and boron were uniformly distributed. The silicon carbide coating was polycrystalline with a columnar structure along the growth direction. The p-B(Si)N/SiC coatings were more uniform, less defective and of better quality than the BN/SiC or the p-BN/SiC coatings.

Wear resistance of WC/Co HVOF-coatings and galvanic Cr coatings modified by diamond nanoparticles

NASA Astrophysics Data System (ADS)

Kandeva, M.; Grozdanova, T.; Karastoyanov, D.; Assenova, E.

2017-02-01

The efforts in the recent 20 years are related to search of ecological solutions in the tribotechnologies for the replacement of galvanic Cr coatings in the contact systems operating under extreme conditions: abrasion, erosion, cavitation, corrosion, shock and vibration loads. One of the solutions is in the composite coatings deposited by high velocity gas-flame process (HVOF). The present paper presents comparative study results for mechanical and tribological characteristics of galvanic Cr coatings without nanoparticles, galvanic Cr coatings modified by diamond nanoparticles NDDS of various concentration 0.6; 10; 15 и 20% obtained under three technological regimes, and composite WC-12Co coating. Comparative results about hardness, wear, wear resistance and friction coefficient are obtained for galvanic Cr-NDDS and WC-12Co coatings operating at equal friction conditions of dry friction on abrasive surface. The WC-12Co coating shows 5.4 to 7 times higher wear resistance compared to the galvanic Cr-NDDS coatings.

The improvement of wave-absorbing ability of silicon carbide fibers by depositing boron nitride coating

NASA Astrophysics Data System (ADS)

Ye, Fang; Zhang, Litong; Yin, Xiaowei; Liu, Yongsheng; Cheng, Laifei

2013-04-01

This work investigated electromagnetic wave (EMW) absorption and mechanical properties of silicon carbide (SiC) fibers with and without boron nitride (BN) coating by chemical vapor infiltration (CVI). The dielectric property and EM shielding effectiveness of SiC fiber bundles before and after being coated by BN were measured by wave guide method. The EM reflection coefficient of SiC fiber laminates with and without BN coating was determined by model calculation and NRL-arc method, respectively. Tensile properties of SiC fiber bundles with and without BN coating were tested at room temperature. Results show that SiC fibers with BN coating had a great improvement of EMW absorbing property because the composites achieved the impedance matching. BN with the low permittivity and dielectric loss contributed to the enhancive introduction and reduced reflection of EMW. The tensile strength and Weibull modulus of SiC fiber bundles coated by BN increased owing to the decrease of defects in SiC fibers and the protection of coating during loading.

Coated Fused Silica Fibers for Enhanced Sensitivity Torsion Pendulum

NASA Technical Reports Server (NTRS)

Numata, Kenji; Horowitz, Jordan; Camp, Jordan

2007-01-01

In order to investigate the fundamental thermal noise limit of a torsion pendulum using a fused silica fiber, we systematically measured and modeled the mechanical losses of thin fused silica fibers coated by electrically conductive thin metal films. Our results indicate that it is possible to achieve a thermal noise limit for coated silica lower by a factor between 3 and 9, depending on the silica diameter, compared to the best tungsten fibers available. This will allow a corresponding increase in sensitivity of torsion pendula used for weak force measurements, including the gravitational constant measurement and ground-based force noise testing for the Laser Interferometer Space Antenna (LISA) mission.

A solid-phase microextraction fiber with carbon nanoparticles as sorbent material prepared by a simple flame-based preparation process.

PubMed

Sun, Min; Feng, Juanjuan; Qiu, Huamin; Fan, Lulu; Li, Leilei; Luo, Chuannan

2013-07-26

A novel carbon nanoparticles-coated solid-phase microextraction (SPME) fiber was prepared via a simple and low-cost flame-based preparation process, with stainless steel wire as support. Surface characteristic of the fiber was studied with scanning electron microscope. A nano-scaled brushy structure was observed. Coupled to gas chromatography (GC), the fiber was used to extract phthalate esters (PAEs) and polycyclic aromatic hydrocarbons (PAHs) in aqueous samples. Analytical performances of the proposed method were investigated under the optimum extraction conditions (extraction temperature, 40°C; content of KCl, 30% (w/v); extraction time, 50min for PAEs and 40min for PAHs) and compared with other reports for the same analytes. Calibration ranges were 0.06-500μgL(-1) for di-n-butyl phthalate (DBP), and 0.1-300μgL(-1) for di-cyclohexyl phthalate (DCHP) and di-(2-ethyl-hexyl) phthalate (DEHP). For the eight PAHs, good linearity was obtained ranging from 0.01 to 150μgL(-1). Limits of detection were 0.005μgL(-1) for three PAEs and 0.001-0.003μgL(-1) for eight PAHs. The fiber exhibited excellent stability. It can be used for 100 times with RSDs of extraction efficiency less than 22.4%. The as-established SPME-GC method was applied to determine PAEs in food-wrap and PAHs in cigarette ash and snow water, and satisfactory results were obtained. The carbon nanoparticles-coated SPME fiber was efficient for sampling of organic compounds from aqueous samples. Copyright © 2013 Elsevier B.V. All rights reserved.

The detection of HBV DNA with gold-coated iron oxide nanoparticle gene probes

NASA Astrophysics Data System (ADS)

Xi, Dong; Luo, XiaoPing; Lu, QiangHua; Yao, KaiLun; Liu, ZuLi; Ning, Qin

2008-03-01

Gold-coated iron oxide nanoparticle Hepatitis B virus (HBV) DNA probes were prepared, and their application for HBV DNA measurement was studied. Gold-coated iron oxide nanoparticles were prepared by the citrate reduction of tetra-chloroauric acid in the presence of iron oxide nanoparticles which were added as seeds. With a fluorescence-based method, the maximal surface coverage of hexaethiol 30-mer oligonucleotides and the maximal percentage of hybridization strands on gold-coated iron oxide nanoparticles were (120 ± 8) oligonucleotides per nanoparticle, and (14 ± 2%), respectively, which were comparable with those of (132 ± 10) and (22 ± 3%) in Au nanoparticle groups. Large network aggregates were formed when gold-coated iron oxide nanoparticle HBV DNA gene probe was applied to detect HBV DNA molecules as evidenced by transmission electron microscopy and the high specificity was verified by blot hybridization. Our results further suggested that detecting DNA with iron oxide nanoparticles and magnetic separator was feasible and might be an alternative effective method.

Self-Assembled Double-Quarter Antireflective Coatings using Silica and Titania Nanoparticles

NASA Astrophysics Data System (ADS)

Lal, Anitesh; Castedo Velasco, Raisa; Mazilu, Dan

2011-03-01

Antireflective coatings have a wide range of applications, from eyeglass and camera lenses, to solar panels and optoelectronic devices, to name just a few. Our study examines several factors that affect the quality of antireflective coatings created by the self-assembly of alternating layers of SiO2 and/or TiO2 nanoparticles and poly(diallyldimethylammonium chloride) polycation on glass substrates. We use a factorial design to investigate the effects of the molarity of the nanoparticle solution, the size of the nanoparticles, the pH of the nanoparticle and polycation solutions, and the number of nanoparticle-polycation bilayers on the optical properties of the films. The first order effects of these factors, as well as their interactions, on the reflectance, transmittance, and uniformity of the coatings are reported.

Spectral engineering of optical fiber through active nanoparticle doping

NASA Astrophysics Data System (ADS)

Lindstrom-James, Tiffany

The spectral engineering of optical fiber is a method of intentional doping of the core region in order to absorb/emit specific wavelengths of light therby providing enhanced performance over current fibers. Efforts here focused on developing an understanding of optically active nanoparticles based on alkaline earth fluorides that could be easily and homogeneously incorporated into the core of a silica based optical fiber preform and result in efficient and tailorable spectral emissions. Doped and undoped calcium, strontium and barium fluoride nanoparticles were successfully synthesized and characterized for their physical, chemical, and optical behavior. Distinct spectroscopic differences as a result of different host materials, varying rare earth doping levels and processing conditions, indicated the ability to influence the spectral behavior of the doped nanoparticle. By using photoluminescence to predict diffusion behavior, the application of a simple one dimensional model for diffusion provided a method for predicting the diffusion coefficient of europium ions in alkaline earth fluorides with order of magnitude accuracy. Modified chemical vapor deposition derived silica preforms were individually solution doped with europium doped alkaline earth fluoride nanoparticles. By using the rare earth doped alkaline earth fluoride nanoparticles as the dopant materials in the core of optical fiber preforms, the resultant optical properties of the glass were significantly influenced by their presence in the core. The incorporation of these rare earth doped alkaline earth fluoride nanoparticles was found to significantly influence the local chemical and structural environment about the rare earth ion, demonstrated homogeneity and uniform distribution of the rare earth dopant and resulted in specifically unique spectral behavior when compared to conventional doping methods. A more detailed structural model of the doped core glass region has been developed based on the

Supercritical fluid technology of nanoparticle coating for new ceramic materials.

PubMed

Aymonier, Cyril; Elissalde, Catherine; Reveron, Helen; Weill, François; Maglione, Mario; Cansell, François

2005-06-01

This work highlights, for the first time, the coating of ferroelectric nanoparticles with a chemical fluid deposition process in supercritical fluids. BaTiO3 nanoparticles of about 50 nm are coated with a shell of a few nanometers of amorphous alumina and can be recovered as a dry powder for processing. The sintering of these core-shell nanoparticles gives access to a ceramic material with very interesting ferroelectric properties, in particular, dielectric losses below 1%.

Ion-imprinted nanoparticles for the concurrent estimation of Pb(II) and Cu(II) ions over a two channel surface plasmon resonance-based fiber optic platform

NASA Astrophysics Data System (ADS)

Shrivastav, Anand Mohan; Gupta, Banshi D.

2018-01-01

We report the design, fabrication, and characterization of an optical fiber sensor based on the surface plasmon resonance (SPR) technique for the simultaneous determination of lead (Pb) and copper (Cu) metal ions in aqueous samples. Two cascade channels over a single optical fiber are fabricated by removing cladding from two well-separated regions of the fiber. SPR working as a transducing mechanism for the sensor is realized by coating thin films of copper and silver over unclad cores of channel I and channel II, respectively. Ion-imprinted nanoparticles for both ions are separately synthesized and coated over the metal-coated unclad cores of the fiber as the recognition layers for sensor fabrication. A first channel having layer of Pb(II) ion-imprinted nanoparticles detects Pb(II) ions and a second channel having layer of Cu(II) ion-imprinted nanoparticles are used for the detection of Cu(II) ions. Both channels are characterized using the wavelength interrogation method. The sensor operates in the range between 0 to 1000 μg/L and 0 to 1000 mg/L for Pb(II) and Cu(II) ions, respectively. These ranges cover water resources and the human body for these ions. The sensitivities of channel I and channel II are found to be 8.19×104 nm/(μg/L) and 4.07×105 nm/(mg/L) near the lowest concentration of Pb(II) and Cu(II) ions, respectively. The sensor can detect concentrations of Pb(II) and Cu(II) ions as low as 4.06 × 10-12 g/L and 8.18 × 10-10 g/L, respectively, which are the least among the reported values in the literature. Further, the probe is simple, cost effective, highly selective, and applicable for online monitoring and remote sensing.

Silica coating of nanoparticles by the sonogel process.

PubMed

Chen, Quan; Boothroyd, Chris; Tan, Gim Hong; Sutanto, Nelvi; Soutar, Andrew McIntosh; Zeng, Xian Ting

2008-02-05

A modified aqueous sol-gel route was developed using ultrasonic power for the silica coating of indium tin oxide (ITO) nanoparticles. In this approach, organosilane with an amino functional group was first used to cover the surface of as-received nanoparticles. Subsequent silica coating was initiated and sustained under power ultrasound irradiation in an aqueous mixture of surface-treated particles and epoxy silane. This process resulted in a thin but homogeneous coverage of silica on the particle surface. Particles coated with a layer of silica show better dispersability in aqueous and organic media compared with the untreated powder. Samples were characterized by high-resolution transmission electron microscopy (HRTEM), X-ray photoelectron spectroscopy (XPS), and the zeta potential.

Investigations of surface coatings to reduce memory effect in plastic scintillator detectors used for radioxenon detection

NASA Astrophysics Data System (ADS)

Bläckberg, L.; Fay, A.; Jõgi, I.; Biegalski, S.; Boman, M.; Elmgren, K.; Fritioff, T.; Johansson, A.; Mårtensson, L.; Nielsen, F.; Ringbom, A.; Rooth, M.; Sjöstrand, H.; Klintenberg, M.

2011-11-01

In this work Al2O3 and SiO2 coatings are tested as Xe diffusion barriers on plastic scintillator substrates. The motivation is improved beta-gamma coincidence detection systems, used to measure atmospheric radioxenon within the verification regime of the Comprehensive Nuclear-Test-Ban Treaty. One major drawback with the current setup of these systems is that the radioxenon tends to diffuse into the plastic scintillator material responsible for the beta detection, resulting in an unwanted memory effect. Here, coatings with thicknesses between 20 and 900 nm have been deposited onto plastic scintillators, and investigated using two different experimental techniques. The results show that all tested coatings reduce the Xe diffusion into the plastic. The reduction is observed to increase with coating thickness for both coating materials. The 425 nm Al2O3 coating is the most successful one, presenting a diffusion reduction of a factor 100, compared to uncoated plastic. In terms of memory effect reduction this coating is thus a viable solution to the problem in question.

The effect of coating on heat generation properties of Iron oxide nanoparticles

NASA Astrophysics Data System (ADS)

Yuan, Yuan

Magnetic nanoparticles have attracted more and more attention for their potential application as heating agents in cancer hyperthermia. The effectiveness of cancer hyperthermia can be increased by using particles that have a higher heat generation rate, quantified by specific absorption rate (SAR), at a smaller applied field. In order to optimize the functionality of nanoparticles as heating agents, it is essential to have a comprehensive understanding of factors that may influence SAR including coating and aggregation. In all biomedical applications, the magnetic particles are coated with surfactants and polymers to enhance biocompatibility, prevent agglomeration and add functionality. Coatings may profoundly influence particles' clustering behavior and magnetic properties. Yet its effect on the heat generation rate of the nanoparticles has been scarcely investigated. In this context, a systematic investigation was carried out in this dissertation in order to understand the impact of the surface coating of magnetic nanoparticles on their heat generation rate. The study also includes investigation of normal nerve cell viability in presence of biofunctionalized magnetic nanoparticles with and without exposure to magnetic heating. Commercially available suspensions of iron oxide nanoparticles with a diameter of approximately 10 nm and different coatings relevant to biomedical applications such as aminosilane, carboxymethyl-dextran, protein A, biotin were extensively characterized. First of all, magnetic phase reduction of magnetite nanoparticles was examined by studying the discrepancy between the volume fraction of magnetic phase calculated from magnetization curve and the magnetic core concentration obtained from Tiron chelation test. The findings indicated that coatings might interact with the surface atoms of the magnetic core and form a magnetically disordered layer reducing the total amount of the magnetic phase. Secondly, the impact of coating and aggregation

Nanoparticle-coated micro-optofluidic ring resonator as a detector for microscale gas chromatographic vapor analysis

NASA Astrophysics Data System (ADS)

Scholten, K.; Collin, W. R.; Fan, X.; Zellers, E. T.

2015-05-01

A vapor sensor comprising a nanoparticle-coated microfabricated optofluidic ring resonator (μOFRR) is introduced. A multilayer film of polyether functionalized, thiolate-monolayer-protected gold nanoparticles (MPN) was solvent cast on the inner wall of the hollow cylindrical SiOx μOFRR resonator structure, and whispering gallery mode (WGM) resonances were generated with a 1550 nm tunable laser via an optical fiber taper. Reversible shifts in the WGM resonant wavelength upon vapor exposure were detected with a photodetector. The μOFRR chip was connected to a pair of upstream etched-Si chips containing PDMS-coated separation μcolumns and calibration curves were generated from the peak-area responses to five volatile organic compounds (VOCs). Calibration curves were linear, and the sensitivities reflected the influence of analyte volatility and analyte-MPN functional group affinity. Sorption-induced changes in film thickness apparently dominate over changes in the refractive index of the film as the determinant of responses for all VOCs. Peaks from the MPN-coated μOFRR were just 20-50% wider than those from a flame ionization detector for similar μcolumn separation conditions, reflecting the rapid response of the sensor for VOCs. The five VOCs were baseline separated in <1.67 min, with detection limits as low as 38 ng.

Nanoparticle-coated micro-optofluidic ring resonator as a detector for microscale gas chromatographic vapor analysis.

PubMed

Scholten, K; Collin, W R; Fan, X; Zellers, E T

2015-05-28

A vapor sensor comprising a nanoparticle-coated microfabricated optofluidic ring resonator (μOFRR) is introduced. A multilayer film of polyether functionalized, thiolate-monolayer-protected gold nanoparticles (MPN) was solvent cast on the inner wall of the hollow cylindrical SiOxμOFRR resonator structure, and whispering gallery mode (WGM) resonances were generated with a 1550 nm tunable laser via an optical fiber taper. Reversible shifts in the WGM resonant wavelength upon vapor exposure were detected with a photodetector. The μOFRR chip was connected to a pair of upstream etched-Si chips containing PDMS-coated separation μcolumns and calibration curves were generated from the peak-area responses to five volatile organic compounds (VOCs). Calibration curves were linear, and the sensitivities reflected the influence of analyte volatility and analyte-MPN functional group affinity. Sorption-induced changes in film thickness apparently dominate over changes in the refractive index of the film as the determinant of responses for all VOCs. Peaks from the MPN-coated μOFRR were just 20-50% wider than those from a flame ionization detector for similar μcolumn separation conditions, reflecting the rapid response of the sensor for VOCs. The five VOCs were baseline separated in <1.67 min, with detection limits as low as 38 ng.

Highly stretchable and conductive fibers enabled by liquid metal dip-coating

NASA Astrophysics Data System (ADS)

Zhang, Qiang; Roach, Devin J.; Geng, Luchao; Chen, Haosen; Qi, H. Jerry; Fang, Daining

2018-03-01

Highly stretchable and conductive fibers have been fabricated by dip-coating of a layer of liquid metal (eutectic gallium indium, EGaIn) on printed silicone elastomer filaments. This fabrication method exploits a nanolayer of oxide skin that rapidly forms on the surface of EGaIn when exposed to air. Through dip-coating, the sticky nature of the oxide skin leads to the formation of a thin EGaIn coating (˜5 μm thick) on the originally nonconductive filaments and renders these fibers excellent conductivity. Electrical characterization shows that the fiber resistance increases moderately as the fiber elongates but always maintains conductivity even when stretched by 800%. Besides this, these fibers possess good cyclic electrical stability with little degradation after hundreds of stretching cycles, which makes them an excellent candidate for stretchable conductors. We then demonstrate a highly stretchable LED circuit as well as a conductive stretchable net that extends the 1D fibers into a 2D configuration. These examples demonstrate potential applications for topologically complex stretchable electronics.

Fabrication and optical characterization of silica optical fibers containing gold nanoparticles.

PubMed

de Oliveira, Rafael E P; Sjödin, Niclas; Fokine, Michael; Margulis, Walter; de Matos, Christiano J S; Norin, Lars

2015-01-14

Gold nanoparticles have been used since antiquity for the production of red-colored glasses. More recently, it was determined that this color is caused by plasmon resonance, which additionally increases the material's nonlinear optical response, allowing for the improvement of numerous optical devices. Interest in silica fibers containing gold nanoparticles has increased recently, aiming at the integration of nonlinear devices with conventional optical fibers. However, fabrication is challenging due to the high temperatures required for silica processing and fibers with gold nanoparticles were solely demonstrated using sol-gel techniques. We show a new fabrication technique based on standard preform/fiber fabrication methods, where nanoparticles are nucleated by heat in a furnace or by laser exposure with unprecedented control over particle size, concentration, and distribution. Plasmon absorption peaks exceeding 800 dB m(-1) at 514-536 nm wavelengths were observed, indicating higher achievable nanoparticle concentrations than previously reported. The measured resonant nonlinear refractive index, (6.75 ± 0.55) × 10(-15) m(2) W(-1), represents an improvement of >50×.

On-line defect detection of aluminum coating using fiber optic sensor

NASA Astrophysics Data System (ADS)

Patil, Supriya S.; Shaligram, A. D.

2015-03-01

Aluminum metallization using the sprayed coating for exhaust mild steel (MS) pipes of tractors is a standard practice for avoiding rusting. Patches of thin metal coats are prone to rusting and are thus considered as defects in the surface coating. This paper reports a novel configuration of the fiber optic sensor for on-line checking the aluminum metallization uniformity and hence for defect detection. An optimally chosen high bright 440 nm BLUE LED (light-emitting diode) launches light into a transmitting fiber inclined at the angle of 60° to the surface under inspection placed adequately. The reflected light is transported by a receiving fiber to a blue enhanced photo detector. The metallization thickness on the coated surface results in visually observable variation in the gray shades. The coated pipe is spirally inspected by a combination of linear and rotary motions. The sensor output is the signal conditioned and monitored with RISHUBH DAS. Experimental results show the good repeatability in the defect detection and coating non-uniformity measurement.

Coupling Light Emitting Diodes with Photocatalyst-Coated Optical Fibers Improves Quantum Yield of Pollutant Oxidation.

PubMed

Ling, Li; Tugaoen, Heather; Brame, Jonathon; Sinha, Shahnawaz; Li, Chuanhao; Schoepf, Jared; Hristovski, Kiril; Kim, Jae-Hong; Shang, Chii; Westerhoff, Paul

2017-11-21

A photocatalyst-coated optical fiber was coupled with a 318 nm ultraviolet-A light emitting diode, which activated the photocatalysts by interfacial photon-electron excitation while minimizing photonic energy losses due to conventional photocatalytic barriers. The light delivery mechanism was explored via modeling of evanescent wave energy produced upon total internal reflection and photon refraction into the TiO 2 surface coating. This work explores aqueous phase LED-irradiated optical fibers for treating organic pollutants and for the first time proposes a dual-mechanistic approach to light delivery and photocatalytic performance. Degradation of a probe organic pollutant was evaluated as a function of optical fiber coating thickness, fiber length, and photocatalyst attachment method and compared against the performance of an equivalent catalyst mass in a completely mixed slurry reactor. Measured and simulated photon fluence through the optical fibers decreased as a function of fiber length, coating thickness, or TiO 2 mass externally coated on the fiber. Thinner TiO 2 coatings achieved faster pollutant removal rates from solution, and dip coating performed better than sol-gel attachment methods. TiO 2 attached to optical fibers achieved a 5-fold higher quantum yield compared against an equivalent mass of TiO 2 suspended in a slurry solution.

Improvement of Interaction in a Composite Structure by Using a Sol-Gel Functional Coating on Carbon Fibers.

PubMed

Szczurek, Anna; Barcikowski, Michał; Leluk, Karol; Babiarczuk, Bartosz; Kaleta, Jerzy; Krzak, Justyna

2017-08-25

The modification of carbon fibers for improving adhesion between fibers and an epoxy resin in composite materials has become the focus of attention. In this work the carbon fiber coating process has been devised in a way preventing the stiffening and clumping of fibers. To improve interactions between coated fibers and a resin in composites, four types of silica coatings with different organic functional groups (3-aminopropyl-coating 1, 3-mercaptopropyl-coating 2, 2-(3,4-epoxycyclohexyl) ethyl-coating 3, methyl-coating 4) were obtained. Scanning electron microscopy (SEM) and atomic force microscopy (AFM) were used to distinguish the changes of a carbon fibers surface after coating deposition. The thickness of the obtained coatings, including the diversity of thickness, was determined by transmission electron microscopy (TEM). The increase in surface free energy (SFE) of modified fibers, including the distinction between the polar and dispersive parts, was examined by wettability measurements using a tensometric test. The developed coating preparation process allowed to cover fibers separately with nanoscale silica layers, which changed their morphology. The introduction of organic functional groups resulted in surface free energy changes, especially an increase in specific polar surface energy components.

Improvement of Interaction in a Composite Structure by Using a Sol-Gel Functional Coating on Carbon Fibers

PubMed Central

Barcikowski, Michał; Leluk, Karol; Babiarczuk, Bartosz; Kaleta, Jerzy

2017-01-01

The modification of carbon fibers for improving adhesion between fibers and an epoxy resin in composite materials has become the focus of attention. In this work the carbon fiber coating process has been devised in a way preventing the stiffening and clumping of fibers. To improve interactions between coated fibers and a resin in composites, four types of silica coatings with different organic functional groups (3-aminopropyl–coating 1, 3-mercaptopropyl–coating 2, 2-(3,4-epoxycyclohexyl) ethyl–coating 3, methyl–coating 4) were obtained. Scanning electron microscopy (SEM) and atomic force microscopy (AFM) were used to distinguish the changes of a carbon fibers surface after coating deposition. The thickness of the obtained coatings, including the diversity of thickness, was determined by transmission electron microscopy (TEM). The increase in surface free energy (SFE) of modified fibers, including the distinction between the polar and dispersive parts, was examined by wettability measurements using a tensometric test. The developed coating preparation process allowed to cover fibers separately with nanoscale silica layers, which changed their morphology. The introduction of organic functional groups resulted in surface free energy changes, especially an increase in specific polar surface energy components. PMID:28841187

Microneedle-mediated transcutaneous immunization with plasmid DNA coated on cationic PLGA nanoparticles.

PubMed

Kumar, Amit; Wonganan, Piyanuch; Sandoval, Michael A; Li, Xinran; Zhu, Saijie; Cui, Zhengrong

2012-10-28

Previously, it was shown that microneedle-mediated transcutaneous immunization with plasmid DNA can potentially induce a stronger immune response than intramuscular injection of the same plasmid DNA. In the present study, we showed that the immune responses induced by transcutaneous immunization by applying plasmid DNA onto a skin area pretreated with solid microneedles were significantly enhanced by coating the plasmid DNA on the surface of cationic nanoparticles. In addition, the net surface charge of the DNA-coated nanoparticles significantly affected their in vitro skin permeation and their ability to induce immune responses in vivo. Transcutaneous immunization with plasmid DNA-coated net positively charged nanoparticles elicited a stronger immune response than with plasmid DNA-coated net negatively charged nanoparticles or by intramuscular immunization with plasmid DNA alone. Transcutaneous immunization with plasmid DNA-coated net positively charged nanoparticles induced comparable immune responses as intramuscular injection of them, but transcutaneous immunization was able to induce specific mucosal immunity and a more balanced T helper type 1 and type 2 response. The ability of the net positively charged DNA-coated nanoparticles to induce a strong immune response through microneedle-mediated transcutaneous immunization may be attributed to their ability to increase the expression of the antigen gene encoded by the plasmid and to more effectively stimulate the maturation of antigen-presenting cells. Copyright © 2012 Elsevier B.V. All rights reserved.

Transfer of Wire Arc-Sprayed Metal Coatings onto Plastic Parts

NASA Astrophysics Data System (ADS)

Bobzin, K.; Öte, M.; Knoch, M. A.; Liao, X.; Hopmann, Ch.; Ochotta, P.

2018-01-01

By means of In-Mold-Metal-Spraying (IMMS), metal coatings deposited by means of arc spraying process (ASP) can be transferred onto plastic parts during injection molding, thus realizing an efficient production of metallized plastic parts. Parts produced by means of IMMS can be used in electrical applications. In the current study, the electrical resistivity of coatings applied with different feedstock materials was determined. As a starting point, pressurized air is used as atomizing gas for ASP. In contrast to Zn coatings, Cu coatings applied with pressurized air exhibit a significantly higher electrical resistivity in comparison with massive material. One possible reason is the more pronounced oxidation of Cu particles during ASP. Therefore, N2 and a mixture of N2 and H2 were used as atomizing gas. As a result, the electrical resistivity of coatings applied by means of IMMS could be significantly reduced. Furthermore, standoff distance, current and pressure of the atomizing gas were varied to investigate the influence of these process parameters on the electrical resistivity of Zn coatings using a full factorial experiment design with center point. It can be observed that the electrical resistivity of the Zn coatings increases with decreasing current and increasing standoff distance and pressure.

Transfer of Wire Arc-Sprayed Metal Coatings onto Plastic Parts

NASA Astrophysics Data System (ADS)

Bobzin, K.; Öte, M.; Knoch, M. A.; Liao, X.; Hopmann, Ch.; Ochotta, P.

2017-12-01

By means of In-Mold-Metal-Spraying (IMMS), metal coatings deposited by means of arc spraying process (ASP) can be transferred onto plastic parts during injection molding, thus realizing an efficient production of metallized plastic parts. Parts produced by means of IMMS can be used in electrical applications. In the current study, the electrical resistivity of coatings applied with different feedstock materials was determined. As a starting point, pressurized air is used as atomizing gas for ASP. In contrast to Zn coatings, Cu coatings applied with pressurized air exhibit a significantly higher electrical resistivity in comparison with massive material. One possible reason is the more pronounced oxidation of Cu particles during ASP. Therefore, N2 and a mixture of N2 and H2 were used as atomizing gas. As a result, the electrical resistivity of coatings applied by means of IMMS could be significantly reduced. Furthermore, standoff distance, current and pressure of the atomizing gas were varied to investigate the influence of these process parameters on the electrical resistivity of Zn coatings using a full factorial experiment design with center point. It can be observed that the electrical resistivity of the Zn coatings increases with decreasing current and increasing standoff distance and pressure.

Magnetic studies of SiO2 coated CoFe2O4 nanoparticles

NASA Astrophysics Data System (ADS)

Limaye, Mukta V.; Singh, Shashi B.; Das, Raja; Poddar, Pankaj; Abyaneh, Majid K.; Kulkarni, Sulabha K.

2017-11-01

Oleic acid capped CoFe2O4 nanoparticles which exhibit a high coercivity of ∼9.47 kOe at room temperature were coated with a robust coating of SiO2. We have used chemical synthesis method to obtain SiO2 coated CoFe2O4 nanoparticles with different weight percentages of CoFe2O4 in SiO2 (1.5, 3.1 and 4.8 wt.%). The morphological investigation of the coated nanoparticles by transmission electron microscopy shows that the particles are spherical with average size ∼160 nm. Infrared spectroscopy reveals that oleic acid capping on the surface of CoFe2O4 nanoparticles is retained after silica coating process. The complete coating of SiO2 on CoFe2O4 nanoparticles is confirmed by X-ray photoelectron spectroscopy as there is no signature of cobalt or iron ions on the surface. Magnetic measurements show that coercivity of SiO2 coated CoFe2O4 particles remains more or less unaffected as in CoFe2O4 nanoparticles at room temperature. In addition, the temperature dependent magnetic measurements show that at 5 K the CoFe2O4 and SiO2 coated 1.5 wt.% CoFe2O4 samples exhibit a very high value of coercivity (∼20 kOe) which is more than twice as compared to room temperature coercivity value (∼9.47 kOe). We conclude that silica coating in our study does not significantly affect the coercivity of CoFe2O4 nanoparticles.

Porous Aromatic Framework 48/Gel Hybrid Material Coated Solid-Phase Microextraction Fiber for the Determination of the Migration of Styrene from Polystyrene Food Contact Materials.

PubMed

Jin, Yuanyuan; Li, Zhongyue; Yang, Lei; Xu, Jun; Zhao, Le; Li, Zhonghao; Niu, Jiajia

2017-01-17

A novel solid-phase microextraction (SPME) fiber was fabricated by a porous aromatic framework 48 (PAF-48)/gel hybrid material through a sol-gel process. PAF-48 is a porous organic framework (POF) material that was polymerized from 1,3,5-triphenylbenzene. The uniform pore structure, high surface area, continuous conjugate network, and hydrophobicity make PAF-48 expected to have special abilities to absorb and extract styrene as well as some other harmful volatile aromatic compounds (VACs). The PAF-48/gel-coated fiber was explored for the extraction of styrene and six VACs (benzene, toluene, ethylbenzene, and xylenes) from aqueous food simulants followed by gas chromatography (GC) separation. The fiber was found to be very sensitive for the determination of the target molecules with wide linear ranges (0.1-200 or 500 μg·kg -1 ), low limits of detection (LODs, 0.003-0.060 μg·kg -1 ), acceptable precisions (intraday relative standard deviation, RSD < 5.9%, interday RSD < 7.3%), and long lifetime (>200 times). Particularly for styrene, the PAF-48/gel-coated fiber exhibited a much lower LOD (0.006 μg·kg -1 ) compared with most of the reported fibers. Moreover, the PAF-48/gel-coated fiber had a high extraction selectivity for styrene and VACs over alcohols, phenols, aromatic amines, and alkanes and show a molecular sieving effect for the different molecule sizes. Finally, the PAF-48/gel-coated SPME fiber was successfully applied in GC for the determination of the specific migrations of styrene and VACs from polystyrene (PS) plastic food contact materials (FCMs).

Ytterbium-doped Y 2O 3 nanoparticle silica optical fibers for high power fiber lasers with suppressed photodarkening

NASA Astrophysics Data System (ADS)

Yoo, S.; Kalita, M. P.; Boyland, A. J.; Webb, A. S.; Standish, R. J.; Sahu, J. K.; Paul, M. C.; Das, S.; Bhadra, S. K.; Pal, M.

2010-09-01

We report efficient laser demonstration and spectroscopic characteristics of a Yb-doped Y 2O 3 (or Y 3Al 5O 12) nanoparticle silica fiber developed by conventional fiber fabrication technique. The spectroscopy study evidences modification in the environment of Yb ions by the Y 2O 3 nanoparticles. As a result, photodarkening induced loss is reduced by 20 times relative to Yb-doped aluminosilicate fibers. The fiber is suitable for power scaling with good laser slope efficiency of 79%.

Evasion of the accelerated blood clearance phenomenon by coating of nanoparticles with various hydrophilic polymers.

PubMed

Ishihara, Tsutomu; Maeda, Taishi; Sakamoto, Haruka; Takasaki, Naoko; Shigyo, Masao; Ishida, Tatsuhiro; Kiwada, Hiroshi; Mizushima, Yutaka; Mizushima, Tohru

2010-10-11

The accelerated blood clearance (ABC) phenomenon is induced upon repeated injections of poly(ethylene glycol) (PEG)-coated colloidal carriers. It is essential to suppress this phenomenon in a clinical setting because the pharmacokinetics must be reproducible. In this study, we evaluated the induction of the ABC phenomenon using nanoparticles coated with various hydrophilic polymers instead of PEG. Nanoparticles encapsulating prostaglandin E1 were prepared by the solvent diffusion method from a blend of poly(lactic acid) (PLA) and block copolymers consisting of various hydrophilic polymers and PLA. Coating of nanoparticles with poly(N-vinyl-2-pyrrolidone) (PVP), poly(4-acryloylmorpholine), or poly(N,N-dimethylacrylamide) led to extended residence of the nanoparticles in blood circulation in rats, although they had a shorter half-life than the PEG-coated nanoparticles. The ABC phenomenon was not induced upon repeated injection of PVP-coated nanoparticles at various time intervals, dosages, or frequencies, whereas it was elicited by PEG-coated nanoparticles. In addition, anti-PVP IgM antibody, which is estimated to be one of the crucial factors for induction of the ABC phenomenon, was not produced after injection of PVP-coated nanoparticles. These results suggest that the use of PVP, instead of PEG, as a coating material for colloidal carriers can evade the ABC phenomenon.

Engineering nanoparticle-coated bacteria as oral DNA vaccines for cancer immunotherapy.

PubMed

Hu, Qinglian; Wu, Min; Fang, Chun; Cheng, Changyong; Zhao, Mengmeng; Fang, Weihuan; Chu, Paul K; Ping, Yuan; Tang, Guping

2015-04-08

Live attenuated bacteria are of increasing importance in biotechnology and medicine in the emerging field of cancer immunotherapy. Oral DNA vaccination mediated by live attenuated bacteria often suffers from low infection efficiency due to various biological barriers during the infection process. To this end, we herein report, for the first time, a new strategy to engineer cationic nanoparticle-coated bacterial vectors that can efficiently deliver oral DNA vaccine for efficacious cancer immunotherapy. By coating live attenuated bacteria with synthetic nanoparticles self-assembled from cationic polymers and plasmid DNA, the protective nanoparticle coating layer is able to facilitate bacteria to effectively escape phagosomes, significantly enhance the acid tolerance of bacteria in stomach and intestines, and greatly promote dissemination of bacteria into blood circulation after oral administration. Most importantly, oral delivery of DNA vaccines encoding autologous vascular endothelial growth factor receptor 2 (VEGFR2) by this hybrid vector showed remarkable T cell activation and cytokine production. Successful inhibition of tumor growth was also achieved by efficient oral delivery of VEGFR2 with nanoparticle-coated bacterial vectors due to angiogenesis suppression in the tumor vasculature and tumor necrosis. This proof-of-concept work demonstrates that coating live bacterial cells with synthetic nanoparticles represents a promising strategy to engineer efficient and versatile DNA vaccines for the era of immunotherapy.

Laser pulse power transmission limits of silica fibers with antireflective coating

NASA Astrophysics Data System (ADS)

Meister, St.; Wosniok, A.; Seewald, G.; Scharfenorth, Ch.; Eichler, H. J.

2005-04-01

Multimode optical fibers are used for the transmission of high power laser pulses and as phase conjugated mirrors by stimulated Brillouin scattering. Both applications are enhanced by antireflection coatings on the fiber end-faces. Fiber transmissions reach more than 99.5% for pulse energies below the threshold of stimulated Brillouin scattering. Laser-induced damage thresholds of the fibers coated with Ta2O5 / SiO2 were measured at 1064 nm and 24 ns pulse duration. A damage threshold of up to 101 J/cm2 could be achieved. The damage morphology was investigated using atomic force microscopy and scanning electron microscopy.

The light transmission and distribution in an optical fiber coated with TiO2 particles.

PubMed

Wang, Wen; Ku, Young

2003-03-01

The light delivery and distribution phenomena along the optical fiber coated with the P-25 TiO(2) particles by dipping was investigated. The surface properties (coverage, roughness and thickness) of the TiO(2) layer coated on the optical fiber were characterized by SEM micrographs. For TiO(2) layer prepared from solutions containing less than 20 wt.% of TiO(2) slurry, the thickness of layer was increased linearly with the TiO(2) slurry content in solutions. The UV light intensity transmitted along a TiO(2)-coated optical fiber decreased more rapidly than that transmitted along a non-coated fiber. Based on the experimental results, the light intensity distribution around a coated optical fiber was modeled to determine the optimum configuration for the design of optical fiber reactors under various operational conditions. Copyright 2002 Elsevier Science Ltd.

Fabrication and Characterization of Conductive Conjugated Polymer-Coated Antheraea mylitta Silk Fibroin Fibers for Biomedical Applications.

PubMed

Gh, Darshan; Kong, Dexu; Gautrot, Julien; Vootla, Shyam Kumar

2017-07-01

Conductive polymers are interesting materials for a number of biological and medical applications requiring electrical stimulation of cells or tissues. Highly conductive polymers (polypyrrole and polyaniline)/Antheraea mylitta silk fibroin coated fibers are fabricated successfully by in situ polymerization without any modification of the native silk fibroin. Coated fibers characterized by scanning electron microscopy confirm the silk fiber surface is covered by conductive polymers. Thermogravimetric analysis reveals preserved thermal stability of silk fiber after coating process. X-ray diffraction of degummed fiber diffraction peaks at around 2θ = 20.4 and 16.5 confirms the preservation of the β-sheet structure typical of degummed silk II fibers. This phenomenon implies that both polypyrrole and polyaniline chains form interactions with peptide linkages in degummed fiber macromolecules, without significantly disrupting protein assembly. Fourier transform infrared spectroscopy of coated fibers indicates hydrogen bonding and electrostatic interactions exist between silk fibroin macromolecules and conductive polymers. Resulting fibers display good conductive properties compared to corresponding conjugated polymers. In vitro analysis (live/dead assay) of the behavior of human immortalized keratinocytes (HaCaTs) on coated fibers demonstrates improved cell-adhesive properties and viability after polymers coating. Hence, polypyrrole- and polyaniline-coated A. mylitta silk fibers are suitable for application in cell culture and for tissue engineering, where electrical conduction properties are required. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

PEG-stearate coated solid lipid nanoparticles as levothyroxine carriers for oral administration

NASA Astrophysics Data System (ADS)

Kashanian, Soheila; Rostami, Elham

2014-03-01

In this study, poly ethylene glycol 100 stearate (PEG 100-S) was used to prepare coated solid lipid nanoparticles with loading levothyroxine sodium (levo-loaded PEG 100-S-coated SLNs) by microemulsification technique. Evaluation of the release kinetic of prepared colloidal carriers was conducted. The particle size and zeta potential of levo-loaded PEG 100-S-coated SLNs have been measured to be 187.5 nm and -23.0 mV, respectively, using photon correlation spectroscopy (PCS). Drug entrapment efficiency (EE) was calculated to be 99 %. Differential scanning calorimetry indicated that the majority of drug loaded in PEG 100-S-coated SLNs were in amorphous state which could be considered desirable for drug delivery. The purpose of this study was to develop a new nanoparticle system, consisting lipid nanoparticles coated with PEG 100-S. The modification procedure led to a reduction in the zeta potential values, varying from -40.0 to -23.0 mV for the uncoated and PEG-coated SLNs, respectively. Stability results of the nanoparticles in gastric and intestinal media show that the low pH of the gastric medium is responsible for the critical aggregation and degradation of the uncoated lipid nanoparticles. PEG 100-S-coated SLNs were more stable due to their polymer coating layer which prevented aggregation of SLNs. Consequently, it is possible that the PEG surrounds the particles reducing the attachment of enzymes and further degradation of the triglyceride cores. Shape and surface morphology of particles were determined by transition electron microscopy and scanning electron microscopy that revealed spherical shape of nanoparticles. In vitro drug release of PEG 100-S-coated SLNs was characterized using diffusion cell which showed a controlled release for drug.

The effect of SiO 2-doped boron nitride multiple coatings on mechanical properties of quartz fibers

NASA Astrophysics Data System (ADS)

Zheng, Yu; Wang, Shubin

2012-01-01

SiO2-doped boron nitride multiple coatings (SiO2/BN multiple coatings) were prepared on quartz fibers surface at 700 °C. Single fiber tensile test was employed to evaluate fiber tensile strength; Scanning Electron Microscopy (SEM) and Transmission Electron Microscopy (TEM) were employed to evaluate morphology and structure of the fibers. Fiber tensile test results indicated that the strength of quartz fibers with SiO2/BN multiple coatings was about twice of the fibers with BN coatings and original fibers which were heated at 700 °C for 10 h. The SiO2/BN multiple coatings would provide compressive stress on quartz fibers, which would help to seal the defects on fiber surface. Furthermore, TEM images showed that the nano-SiO2 powders crystallized in advance of quartz fibers, which would suppress crystallization of quartz fibers and reduce damage from crystallization. Thus, nano-SiO2 powders would help to keep mechanical properties of quartz fibers.

Substrates coated with silver nanoparticles as a neuronal regenerative material

PubMed Central

Alon, Noa; Miroshnikov, Yana; Perkas, Nina; Nissan, Ifat; Gedanken, Aharon; Shefi, Orit

2014-01-01

Much effort has been devoted to the design of effective biomaterials for nerve regeneration. Here, we report the novel use of silver nanoparticles (AgNPs) as regenerative agents to promote neuronal growth. We grew neuroblastoma cells on surfaces coated with AgNPs and studied the effect on the development of the neurites during the initiation and the elongation growth phases. We find that the AgNPs function as favorable anchoring sites, and the growth on the AgNP-coated substrates leads to a significantly enhanced neurite outgrowth. Cells grown on substrates coated with AgNPs have initiated three times more neurites than cells grown on uncoated substrates, and two times more than cells grown on substrates sputtered with a plain homogenous layer of silver. The growth of neurites on AgNPs in the elongation phase was enhanced as well. A comparison with substrates coated with gold nanoparticles (AuNPs) and zinc oxide nanoparticles (ZnONPs) demonstrated a clear silver material-driven promoting effect, in addition to the nanotopography. The growth on substrates coated with AgNPs has led to a significantly higher number of initiating neurites when compared to substrates coated with AuNPs or ZnONPs. All nanoparticle-coated substrates affected and promoted the elongation of neurites, with a significant positive maximal effect for the AgNPs. Our results, combined with the well-known antibacterial effect of AgNPs, suggest the use of AgNPs as an attractive nanomaterial – with dual activity – for neuronal repair studies. PMID:24872701

Ceramic fiber insulation impregnated with an infra-red retardant coating and method for production thereof

NASA Technical Reports Server (NTRS)

Zinn, Alfred A. (Inventor); Tarkanian, Ryan Jeffrey (Inventor)

2007-01-01

The invented insulation is a ceramic fiber insulation wherein the ceramic fibers are treated with a coating which contains transition metal oxides. The invented process for coating the insulation is a process of applying the transition metal oxide coating to the fibers of the insulation after the fibers have been formed into a tile or other porous body. The coating of transition metal oxide lowers the transmittance of radiation through the insulation thereby lowering the temperature of the backface of the insulation and better protecting the structure that underlies the insulation.

Influence of natural organic matter (NOM) coatings on nanoparticle adsorption onto supported lipid bilayers.

PubMed

Bo, Zhang; Avsar, Saziye Yorulmaz; Corliss, Michael K; Chung, Minsub; Cho, Nam-Joon

2017-10-05

As the worldwide usage of nanoparticles in commercial products continues to increase, there is growing concern about the environmental risks that nanoparticles pose to biological systems, including potential damage to cellular membranes. A detailed understanding of how different types of nanoparticles behave in environmentally relevant conditions is imperative for predicting and mitigating potential membrane-associated toxicities. Herein, we investigated the adsorption of two popular nanoparticles (silver and buckminsterfullerene) onto biomimetic supported lipid bilayers of varying membrane charge (positive and negative). The quartz crystal microbalance-dissipation (QCM-D) measurement technique was employed to track the adsorption kinetics. Particular attention was focused on understanding how natural organic matter (NOM) coatings affect nanoparticle-bilayer interactions. Both types of nanoparticles preferentially adsorbed onto the positively charged bilayers, although NOM coatings on the nanoparticle and lipid bilayer surfaces could either inhibit or promote adsorption in certain electrolyte conditions. While past findings showed that NOM coatings inhibit membrane adhesion, our findings demonstrate that the effects of NOM coatings are more nuanced depending on the type of nanoparticle and electrolyte condition. Taken together, the results demonstrate that NOM coatings can modulate the lipid membrane interactions of various nanoparticles, suggesting a possible way to improve the environmental safety of nanoparticles. Copyright © 2017 Elsevier B.V. All rights reserved.

Targeting to carcinoma cells with chitosan- and starch-coated magnetic nanoparticles for magnetic hyperthermia.

PubMed

Kim, Dong-Hyun; Kim, Kyoung-Nam; Kim, Kwang-Mahn; Lee, Yong-Keun

2009-01-01

The delivery of hyperthermic thermoseeds to a specific target site with minimal side effects is an important challenge in targeted hyperthermia, which employs magnetic method and functional polymers. An external magnetic field is used to control the site-specific targeting of the magnetic nanoparticles. Polymer-coated magnetic nanoparticles can confer a higher affinity to the biological cell membranes. In this study, uncoated, chitosan-coated, and starch-coated magnetic nanoparticles were synthesized for use as a hyperthermic thermoseed. Each sample was examined with respect to their applications to hyperthermia using XRD, VSM, and FTIR. In addition, the temperature changes under an alternating magnetic field were observed. As in vitro tests, the magnetic responsiveness of chitosan- and starch-coated magnetite was determined by a simple blood vessel model under various intensities of magnetic field. L929 normal cells and KB carcinoma cells were used to examine the cytotoxicity and affinity of each sample using the MTT method. The chitosan-coated magnetic nanoparticles generated a higher DeltaT of 23 degrees C under an AC magnetic field than the starch-coated magnetite, and the capturing rate of the particles was 96% under an external magnetic field of 0.4 T. The highest viability of L929 cells was 93.7%. Comparing the rate of KB cells capture with the rate of L929 cells capture, the rate of KB cells capture relatively increased with 10.8% in chitosan-coated magnetic nanoparticles. Hence, chitosan-coated magnetic nanoparticles are biocompatible and have a selective affinity to KB cells. The targeting of magnetic nanoparticles in hyperthermia was improved using a controlled magnetic field and a chitosan-coating. Therefore, chitosan-coated magnetic nanoparticles are expected to be promising materials for use in magnetic targeted hyperthermia. 2008 Wiley Periodicals, Inc.

Material Properties of Silicon Carbide Fibers with Continuously Applied Sol-Gel Alumina Coatings

DTIC Science & Technology

1990-12-01

71 Coating Characterization ...................... 73 iii Two-Dimensional Plane Strain Analysis .................. 78 VI ...Axial Load in the Coating of Fiber Serie T ...... .82 vi List of Figures (continued) Figure Page 39. Tangential Stress Due to Axial Load in the Coating...residual stress will be presented 17 Fiur Vi o a CaFber EfIVfef Sic=’/. Figure 1. Sectional View of a Coated Fiber first, since these stresses are of

Brain damage and behavioural disorders in fish induced by plastic nanoparticles delivered through the food chain.

PubMed

Mattsson, Karin; Johnson, Elyse V; Malmendal, Anders; Linse, Sara; Hansson, Lars-Anders; Cedervall, Tommy

2017-09-13

The tremendous increases in production of plastic materials has led to an accumulation of plastic pollution worldwide. Many studies have addressed the physical effects of large-sized plastics on organisms, whereas few have focused on plastic nanoparticles, despite their distinct chemical, physical and mechanical properties. Hence our understanding of their effects on ecosystem function, behaviour and metabolism of organisms remains elusive. Here we demonstrate that plastic nanoparticles reduce survival of aquatic zooplankton and penetrate the blood-to-brain barrier in fish and cause behavioural disorders. Hence, for the first time, we uncover direct interactions between plastic nanoparticles and brain tissue, which is the likely mechanism behind the observed behavioural disorders in the top consumer. In a broader perspective, our findings demonstrate that plastic nanoparticles are transferred up through a food chain, enter the brain of the top consumer and affect its behaviour, thereby severely disrupting the function of natural ecosystems.

Poly(vinylpyrrolidone) coated iron nanoparticles in polar aprotic solvent.

PubMed

Ban, Zhihui; Cushing, Brian L; O'Connor, Charles J

2008-04-01

Poly(vinylpyrrolidone) (PVP) coated iron nanoparticles which show well-defined core-shell structures have been successfully synthesized in a polar aprotic solvent. In this approach, PVP was employed not as capping agent, but as coating polymer directly applied to the metallic (iron) core nanoparticles. The morphologies, structures, compositions and magnetic properties of the products were investigated by transmission electron microscopy (TEM), X-ray powder diffraction (XRD), energy dispersive X-ray spectroscopy (EDXS), SQUID magnetometry and FTIR spectroscopy.

Synthesis and application of surfactants coated magnetite nanoparticles for demulsification of crude oil in water emulsion

NASA Astrophysics Data System (ADS)

Yau, Xin Hui; Khe, Cheng Seong; Liu, Wei Wen; Lai, Chin Wei; Oo, Zeya

2017-10-01

Magnetite nanoparticles were synthesized through co-precipitation method, in which surfactant such as polyvinylpyrrolidone (PVP) and sodium dodecyl benzene sulfonate (SDBS) were applied as stabilizing agent. Various techniques were employed to characterize the synthesized magnetite nanoparticles. Magnetite nanoparticles with spinel structure are successfully synthesized and confirmed by X-ray diffraction (XRD). X-ray photoelectron spectroscopy (XPS) and Fourier transform infrared spectroscopy (FTIR) results proved that surface of magnetite nanoparticles were successfully coated with PVP and SDBS. From the transmission electron microscope (TEM), it showed that surfactant coated magnetite nanoparticles possess smaller particle size than that of bare magnetite nanoparticles. In comparison with SDBS, PVP has a better capping efficiency and the PVP coated magnetite nanoparticles have an average particle size of 10.8 nm. In addition, surfactant coated magnetite nanoparticles also exhibited lower value of saturation magnetization (Ms). Lower value of Ms might be attributed to the small sized nanoparticles. All magnetite nanoparticles synthesized with and without surfactant showed superparamagnetic behaviour. Bare and surfactant coated magnetite nanoparticles have been utilized as a demulsifier for crude oil in water emulsion. Those nanoparticles that produced using SDBS (ED= 87%) showed higher efficiency than that of PVP coated (ED=80%) and bare magnetite nanoparticles (ED=85%) in demulsification tests.

Guanidine Soaps As Vehicles For Coating Ceramic Fibers

NASA Technical Reports Server (NTRS)

Philipp, Warren H.; Veitch, Lisa C.; Jaskowiak, Martha H.

1994-01-01

Soaps made from strong organic base guanidine and organic fatty acids serve as vehicles and binders for coating ceramic fibers, various smooth substrates, and other problematic surfaces with thin precious-metal or metal-oxide films. Films needed to serve as barriers to diffusion in fiber/matrix ceramic composite materials. Guanidine soaps entirely organic and burn off, leaving no residues.

Improving the interfacial and mechanical properties of short glass fiber/epoxy composites by coating the glass fibers with cellulose nanocrystals

Treesearch

A. Asadi; M. Miller; Robert Moon; K. Kalaitzidou

2016-01-01

In this study, the interfacial and mechanical properties of cellulose nanocrystals (CNC) coated glass fiber/epoxy composites were investigated as a function of the CNC content on the surface of glass fibers (GF). Chopped GF rovings were coated with CNC by immersing the GF in CNC (0–5 wt%) aqueous suspensions. Single fiber fragmentation (SFF) tests showed that the...

Self-Cleaning Ceramic Tiles Produced via Stable Coating of TiO₂ Nanoparticles.

PubMed

Shakeri, Amid; Yip, Darren; Badv, Maryam; Imani, Sara M; Sanjari, Mehdi; Didar, Tohid F

2018-06-13

The high photocatalytic power of TiO₂ nanoparticles has drawn great attention in environmental and medical applications. Coating surfaces with these particles enables us to benefit from self-cleaning properties and decomposition of pollutants. In this paper, two strategies have been introduced to coat ceramic tiles with TiO₂ nanoparticles, and the self-cleaning effect of the surfaces on degradation of an organic dye under ultraviolent (UV) exposure is investigated. In the first approach, a simple one-step heat treatment method is introduced for coating, and different parameters of the heat treatment process are examined. In the second method, TiO₂ nanoparticles are first aminosilanized using (3-Aminopropyl)triethoxysilane (APTES) treatment followed by their covalently attachment onto CO₂ plasma treated ceramic tiles via N -(3-Dimethylaminopropyl)- N ′-ethylcarbodiimide hydrochloride (EDC) and N -Hydroxysuccinimide (NHS) chemistry. We monitor TiO₂ nanoparticle sizes throughout the coating process using dynamic light scattering (DLS) and characterize developed surfaces using X-ray photoelectron spectroscopy (XPS). Moreover, hydrophilicity of the coated surfaces is quantified using a contact angle measurement. It is shown that applying a one-step heat treatment process with the optimum temperature of 200 °C for 5 h results in successful coating of nanoparticles and rapid degradation of dye in a short time. In the second strategy, the APTES treatment creates a stable covalent coating, while the photocatalytic capability of the particles is preserved. The results show that coated ceramic tiles are capable of fully degrading the added dyes under UV exposure in less than 24 h.

Photo-crosslinked hyaluronic acid coated upconverting nanoparticles

NASA Astrophysics Data System (ADS)

Mrazek, Jiri; Kettou, Sofiane; Matuska, Vit; Svozil, Vit; Huerta-Angeles, Gloria; Pospisilova, Martina; Nesporova, Kristina; Velebny, Vladimir

2017-02-01

Hyaluronic acid (HA)-coated inorganic nanoparticles display enhanced interaction with the CD44 receptors which are overexpressed in many types of cancer cells. Here, we describe a modification of core-shell β-NaY0.80Yb0.18Er0.02F4@NaYF4 nanoparticles (UCNP) by HA derivative bearing photo-reactive groups. UCNP capped with oleic acid were firstly transferred to aqueous phase by an improved protocol using hydrochloric acid or lactic acid treatment. Subsequently, HA bearing furanacryloyl moieties (HA-FU) was adsorbed on the nanoparticle surface and crosslinked by UV irradiation. The crosslinking resulted in stable HA coating, and no polymer desorption was observed. As-prepared UCNP@HA-FU show a hydrodynamic diameter of about 180 nm and are colloidally stable in water and cell culture media. The cellular uptake by normal human fibroblasts and MDA MB-231 cancer cell line was investigated by upconversion luminescence imaging.

Study of the technics of coating stripping and FBG writing on polyimide fiber

NASA Astrophysics Data System (ADS)

Song, ZhiQiang; Qi, HaiFeng; Ni, JiaSheng; Wang, Chang

2017-10-01

Compared with ordinary optical fiber, polyimide fiber has the characteristics of high temperature resistance and high strength, which has important application in the field of optical fiber sensing. The common methods of polyimide coating stripping were introduced in this paper, including high temperature stripping, chemical stripping and arc ablation. In order to meet the requirements of FBG writing technology, a method using argon ion laser ablation coating was proposed. The method can precisely control the stripping length of the coating and completely does not affect the tensile strength of the optical fiber. According to the experiment, the fabrication process of polyimide FBG is stripping-hydrogen loadingwriting. Under the same conditions, 10 FBG samples were fabricated with good uniformity of wavelength bandwidth and reflectivity. UV laser ablation of polyimide coating has been proved to be a safe, reliable and efficient method.

Microneedle-mediated transcutaneous immunization with plasmid DNA coated on cationic PLGA nanoparticles

PubMed Central

Kumar, Amit; Wonganan, Piyanuch; Sandoval, Michael A.; Li, Xinran; Zhu, Saijie; Cui, Zhengrong

2012-01-01

Previously, it was shown that microneedle-mediated transcutaneous immunization with plasmid DNA can potentially induce a stronger immune response than intramuscular injection of the same plasmid DNA. In the present study, we showed that the immune responses induced by transcutaneous immunization by applying plasmid DNA onto a skin area pretreated with solid microneedles were significantly enhanced by coating the plasmid DNA on the surface of cationic nanoparticles. In addition, the net surface charge of the DNA-coated nanoparticles significantly affected their in vitro skin permeation and their ability to induce immune responses in vivo. Transcutaneous immunization with plasmid DNA-coated net positively charged anoparticles elicited a stronger immune response than with plasmid DNA-coated net negatively charged nanoparticles or by intramuscular immunization with plasmid DNA alone. Transcutaneous immunization with plasmid DNA-coated net positively charged nanoparticles induced comparable immune responses as intramuscular injection of them, but transcutaneous immunization was able to induce specific mucosal immunity and a more balanced T helper type 1 and type 2 response. The ability of the net positively charged DNA-coated nanoparticles to induce a strong immune response through microneedle-mediated transcutaneous immunization may be attributed to their ability to increase the expression of the antigen gene encoded by the plasmid and to more effectively stimulate the maturation of antigen-presenting cells. PMID:22921518

Synthesis of Ag/CNT hybrid nanoparticles and fabrication of their Nylon-6 polymer nanocomposite fibers for antimicrobial applications

NASA Astrophysics Data System (ADS)

Rangari, Vijaya K.; Mohammad, Ghouse M.; Jeelani, Shaik; Hundley, Angel; Vig, Komal; Ram Singh, Shree; Pillai, Shreekumar

2010-03-01

Ag-coated CNTs hybrid nanoparticles (Ag/CNTs) were prepared by ultrasonic irradiation of dimethylformamide (DMF) and silver (I) acetate precursors in the presence of CNTs. The morphology of Ag/CNTs was characterized using x-ray diffraction and transmission electron microscopy (TEM) techniques. The Nylon-6 powder and 1 wt% Ag/CNTs mixture was dispersed uniformly using a noncontact spinning technique. The dried mixture was melted in a single screw extrusion machine and then extruded through an orifice. Extruded filaments were later stretched and stabilized by sequentially passing them through a set of tension adjusters and a secondary heater. The Nylon-6/Ag/CNT hybrid polymer nanocomposite (HPNC) fibers, which were of ~ 80 µm size, were tested for their tensile properties. The failure stress and modulus of the extruded HPNC fibers (doped with 1% Ag/CNTs) was about 72.19 % and 342.62% higher than the neat extruded Nylon-6 fiber, respectively. DSC results indicated an increase in the thermal stability and crystallization for HPNC fibers. The antibacterial activity of the Ag-coated CNTs, commercial Ag, neat Nylon-6 and plain CNTs were evaluated. Ag-coated CNTs at 25 µg demonstrated good antimicrobial activity against four common bacterial pathogens as tested by the Kirby-Bauer assay. The mean diameters of the zones of inhibition were 27.9 ± 6.72 mm, 19.4 ± 3.64 mm, 21.9 ± 4.33 mm, and 24.1 ± 4.14 mm, respectively, for Staphylococcus aureus, Streptococcus pyogenes, Escherichia coli and Salmonella enterica serovar Typhimurium. By comparison, those obtained using the broad spectrum antibiotic amoxicillin-clavulanic acid were 37.7 ± 2.13 mm, 28.6 ± 4.27 mm, 22.6 ± 1.27 mm, and 27.0 ± 1.41 mm, respectively, for the same strains. The zones of inhibition obtained for Nylon-6 Ag-coated CNT powder at 25 µg were also high, ranging from 15.2 to 25.3 mm in contrast to commercial silver or neat Nylon-6, which did not inhibit the bacterial strains tested. Further, the

Fiber temperature sensor with nanostructured cladding by TiO2 nanoparticles self-assembled onto a side polished optical fiber

NASA Astrophysics Data System (ADS)

Yang, Bing; Chen, Zhe; Wang, Yiting; Zhang, Jun; Liao, Guozhen; Tian, Zhengwen; Yu, Jianhui; Tang, Jieyuan; Luo, Yunhan; Lu, Huihui

2015-07-01

A temperature fiber sensor with nanostructured cladding composed ted by titanium dioxide (TiO2) nanoparticles was demonstrated. The nanoparticles self-assembled onto a side polished optical fiber (SPF). The enhancement of interaction between the propagating light and the TiO2 nanoparticles (TN) can be obtained via strong evanescent field of the SPF. The strong light-TN interaction gives rise to temperature sensing with a optical power variation of ~4dB in SPF experimentally for an environment temperature ranging from -7.8°C to 77.6°C. The novel temperature sensor shows a sensitivity of ~0.044 dB/°C. The TN-based fiber-optic temperature sensor is facile to manufactured, compatible with fiber-optic interconnections and high potential in photonics applications.

Femtosecond laser direct-write of optofluidics in polymer-coated optical fiber

NASA Astrophysics Data System (ADS)

Joseph, Kevin A. J.; Haque, Moez; Ho, Stephen; Aitchison, J. Stewart; Herman, Peter R.

2017-03-01

Multifunctional lab in fiber technology seeks to translate the accomplishments of optofluidic, lab on chip devices into silica fibers. a robust, flexible, and ubiquitous optical communication platform that can underpin the `Internet of Things' with distributed sensors, or enable lab on chip functions deep inside our bodies. Femtosecond lasers have driven significant advances in three-dimensional processing, enabling optical circuits, microfluidics, and micro-mechanical structures to be formed around the core of the fiber. However, such processing typically requires the stripping and recoating of the polymer buffer or jacket, increasing processing time and mechanically weakening the device. This paper reports on a comprehensive assessment of laser damage in urethane-acrylate-coated fiber. The results show a sufficient processing window is available for femtosecond laser processing of the fiber without damaging the polymer jacket. The fiber core, cladding, and buffer could be simultaneously processed without removal of the buffer jacket. Three-dimensional lab in fiber devices were successfully fabricated by distortion-free immersionlens focusing, presenting fiber-cladding optical circuits and progress towards chemically-etched channels, microfluidic cavities, and MEMS structure inside buffer-coated fiber.

Fiber Optic Magnetic Field Sensors Using Metallic Glass Coatings.

NASA Astrophysics Data System (ADS)

Wang, Yu.

1990-01-01

In this thesis we have investigated the use of a magnetostrictive material with a single-mode optical fiber for detecting weak magnetic fields. The amorphous alloy Metglas^circler 2605SC (Fe_{81}B_ {13.5}Si_{3.5} C_2) was chosen as the magnetostrictive material because of the combination of its large magnetostriction and small magnetic anisotropy field among all available metals. For efficient coupling between the magnetostrictive material and the optical fiber, the magnetostrictive material was directly deposited onto the single-mode optical fiber. The coated fibers were used as the sensing element in the fiber optic magnetic field sensor (FOMS). Very high quality thick metallic glass films of the Metglas 2605 SC have been deposited using triode-magneton sputtering. This is the first time such material has been successfully deposited onto an optical fiber or onto any other substrate. The films were also deposited onto glass slides to allow the study of the magnetic properties of the film. The thicknesses of these films were 5-15 mum. The magnetic property of primary interest for our sensor application is the induced longitudinal magnetostrictive strain. However, the other magnetic properties such as magnetic anisotropy, surface and bulk coercivities, magnetic homogeneity and magnetization all affect the magnetostrictive response of the material. We have used ferromagnetic resonance (FMR) at microwave frequencies to study the magnetic anisotropy and homogeneity; vibrating sample magnetometry (VSM) to study the bulk magnetic hysteresis responses and coercivity; and the longitudinal magneto-optic kerr effect (LMOKE) to study the surface magnetic hysteresis responses and coercivity. The isothermalmagnetic annealing effect on these properties has also been studied in detail. The fiber optic magnetic field sensor constructed using the metallic-glass-coated fiber was tested. An electronic feedback control loop using a PZT cylinder was constructed for stabilizing the

Human-like collagen protein-coated magnetic nanoparticles with high magnetic hyperthermia performance and improved biocompatibility

NASA Astrophysics Data System (ADS)

Liu, Xiaoli; Zhang, Huan; Chang, Le; Yu, Baozhi; Liu, Qiuying; Wu, Jianpeng; Miao, Yuqing; Ma, Pei; Fan, Daidi; Fan, Haiming

2015-01-01

Human-like collagen (HLC)-coated monodispersed superparamagnetic Fe3O4 nanoparticles have been successfully prepared to investigate its effect on heat induction property and cell toxicity. After coating of HLC, the sample shows a faster rate of temperature increase under an alternating magnetic field although it has a reduced saturation magnetization. This is most probably a result of the effective heat conduction and good colloid stability due to the high charge of HLC on the surface. In addition, compared with Fe3O4 nanoparticles before coating with HLC, HLC-coated Fe3O4 nanoparticles do not induce notable cytotoxic effect at higher concentration which indicates that HLC-coated Fe3O4 nanoparticles has improved biocompatibility. Our results clearly show that Fe3O4 nanoparticles after coating with HLC not only possess effective heat induction for cancer treatment but also have improved biocompatibility for biomedicine applications.

Alterations in nanoparticle protein corona by biological surfactants: impact of bile salts on β-lactoglobulin-coated gold nanoparticles.

PubMed

Winuprasith, Thunnalin; Chantarak, Sirinya; Suphantharika, Manop; He, Lili; McClements, David Julian

2014-07-15

The impact of biological surfactants (bile salts) on the protein (β-lactoglobulin) corona surrounding gold nanoparticles (200 nm) was studied using a variety of analytical techniques at pH 7: dynamic light scattering (DLS); particle electrophoresis (ζ-potential); UV-visible (UV) spectroscopy; transmission electron microscopy (TEM); and surface-enhanced Raman scattering (SERS). The bile salts adsorbed to the protein-coated nanoparticle surfaces and altered their interfacial composition, charge, and structure. SERS spectra of protein-coated nanoparticles after bile salt addition contained bands from both protein and bile salts, indicating that the protein was not fully displaced by the bile salts. UV, DLS and TEM techniques also indicated that the protein coating was not fully displaced from the nanoparticle surfaces. The impact of bile salts could be described by an orogenic mechanism: mixed interfaces were formed that consisted of islands of aggregated proteins surrounded by a sea of bile salts. This knowledge is useful for understanding the interactions of bile salts with protein-coated colloidal particles, which may be important for controlling the fate of colloidal delivery systems in the human gastrointestinal tract, or the gastrointestinal fate of ingested inorganic nanoparticles. Copyright © 2014 Elsevier Inc. All rights reserved.

Synthesis and characterization of polymer-coated manganese ferrite nanoparticles as controlled drug delivery

NASA Astrophysics Data System (ADS)

Wang, Guangshuo; Zhao, Dexing; Ma, Yingying; Zhang, Zhixiao; Che, Hongwei; Mu, Jingbo; Zhang, Xiaoliang; Zhang, Zheng

2018-01-01

In this study, monodisperse and superparamagnetic manganese ferrite (MnFe2O4) nanoparticles have been synthesized by a one-pot sonochemical method using polyvinylpyrrolidone (PVP) as stabilizer. The as-prepared MnFe2O4 nanoparticles were investigated systematically by TEM, XRD, FTIR, XPS, SQUID and MTT. The TEM observation showed that the PVP-coated MnFe2O4 nanoparticles had uniform dispersion with narrow particle size distribution. The magnetization curves demonstrated superparamagnetic properties of the coated MnFe2O4 nanoparticles with good hydrophilicity at room temperature. The in vitro cytotoxicity experiments exhibited negligible cytotoxicity of the obtained PVP-coated MnFe2O4 nanoparticles even at the high concentration of 150 μg/mL after 24 h treatment. More importantly, anti-cancer model drug of doxorubicin hydrochloride (DOX) was loaded on the surface of MnFe2O4 nanoparticles. The drug loading capacity of the developed nanocarrier reached 0.45 mg/mg and the loaded DOX exhibited interesting pH-dependent release behavior. In conclusion, the as-prepared PVP-coated MnFe2O4 nanoparticles were proposed as a potential candidate for controlled drug delivery.

ZnO nanorod array polydimethylsiloxane composite solid phase micro-extraction fiber coating: fabrication and extraction capability.

PubMed

Wang, Dan; Wang, Qingtang; Zhang, Zhuomin; Chen, Guonan

2012-01-21

ZnO nanorod array coating is a novel kind of solid-phase microextraction (SPME) fiber coating which shows good extraction capability due to the nanostructure. To prepare the composite coating is a good way to improve the extraction capability. In this paper, the ZnO nanorod array polydimethylsiloxane (PDMS) composite SPME fiber coating has been prepared and its extraction capability for volatile organic compounds (VOCs) has been studied by headspace sampling the typical volatile mixed standard solution of benzene, toluene, ethylbenzene and xylene (BTEX). Improved detection limit and good linear ranges have been achieved for this composite SPME fiber coating. Also, it is found that the composite SPME fiber coating shows good extraction selectivity to the VOCs with alkane radicals.

[Fusion implants of carbon fiber reinforced plastic].

PubMed

Früh, H J; Liebetrau, A; Bertagnoli, R

2002-05-01

Carbon fiber reinforced plastics (CFRP) are used in the medical field when high mechanical strength, innovative design, and radiolucency (see spinal fusion implants) are needed. During the manufacturing process of the material CFRP carbon fibers are embedded into a resin matrix. This resin material could be thermoset (e.g., epoxy resin EPN/DDS) or thermoplastic (e.g., PEAK). CFRP is biocompatible, radiolucent, and has higher mechanical capabilities compared to other implant materials. This publication demonstrates the manufacturing process of fusion implants made of a thermoset matrix system using a fiber winding process. The material has been used clinically since 1994 for fusion implants of the cervical and lumbar spine. The results of the fusion systems CORNERSTONE-SR C (cervical) and UNION (lumbar) showed no implant-related complications. New implant systems made of this CFRP material are under investigation and are presented.

Solid-stabilized emulsion formation using stearoyl lactylate coated iron oxide nanoparticles

NASA Astrophysics Data System (ADS)

Vengsarkar, Pranav S.; Roberts, Christopher B.

2014-10-01

Iron oxide nanoparticles can exhibit highly tunable physicochemical properties that are extremely important in applications such as catalysis, biomedicine and environmental remediation. The small size of iron oxide nanoparticles can be used to stabilize oil-in-water Pickering emulsions due to their high energy of adsorption at the interface of oil droplets in water. The objective of this work is to investigate the effect of the primary particle characteristics and stabilizing agent chemistry on the stability of oil-in-water Pickering emulsions. Iron oxide nanoparticles were synthesized by the co-precipitation method using stoichiometric amounts of Fe2+ and Fe3+ salts. Sodium stearoyl lactylate (SSL), a Food and Drug Administration approved food additive, was used to functionalize the iron oxide nanoparticles. SSL is useful in the generation of fat-in-water emulsions due to its high hydrophilic-lipophilic balance and its bilayer-forming capacity. Generation of a monolayer or a bilayer coating on the nanoparticles was controlled through systematic changes in reagent concentrations. The coated particles were then characterized using various analytical techniques to determine their size, their crystal structure and surface functionalization. The capacity of these bilayer coated nanoparticles to stabilize oil-in-water emulsions under various salt concentrations and pH values was also systematically determined using various characterization techniques. This study successfully demonstrated the ability to synthesize iron oxide nanoparticles (20-40 nm) coated with SSL in order to generate stable Pickering emulsions that were pH-responsive and resistant to significant destabilization in a saline environment, thereby lending themselves to applications in advanced oil spill recovery and remediation.

Design of Oil Viscosity Sensor Based on Plastic Optical Fiber

NASA Astrophysics Data System (ADS)

Yunus, Muhammad; Arifin, A.

2018-03-01

A research of plastic optical fiber based sensors have been studied for measurement of oil viscosity. This sensor was made with straight configuration, U configuration, and gamma configuration have two types, there are optical fiber sensor with cladding and without cladding. Viscosity sensor was made, dipped into an oil sample with a concentration of viscosity percentage about 270 mPa.s - 350 mPa.s. The light from the LED propagated into the optical fiber, then it was received by the photodetector converted to output power. When plastic optical fiber dipped into an oil sample, viscosity of oil affect increase of refractive index on optical fiber resulting in a bigger loss of power so the light intensity will be smaller, consequences the measured output power will be smaller. Sensitivity and resolution viscosity sensor without cladding peel showed the best result rather than viscosity sensor with cladding peel. The best result in the measurement showed in gamma configuration with 3 cm length of cladding peel and the diameter of bending 0,25 cm is the range 103,090 nWatt, sensitivity 1,289 nWatt/mPa.s, and resolution 0,776 mPa.s. This method is effectively and efficiently used as an oil viscosity sensor with high sensitivity and resolution.

Synthesis and characterization of pHLIP® coated gold nanoparticles.

PubMed

Daniels, Jennifer L; Crawford, Troy M; Andreev, Oleg A; Reshetnyak, Yana K

2017-07-01

Novel approaches in synthesis of spherical and multispiked gold nanoparticles coated with polyethylene glycol (PEG) and pH Low Insertion Peptide (pHLIP ® ) were introduced. The presence of a tumor-targeting pHLIP ® peptide in the nanoparticle coating enhances the stability of particles in solution and promotes a pH-dependent cellular uptake. The spherical particles were prepared with sodium citrate as a gold reducing agent to form particles of 7.0±2.5 nm in mean metallic core diameter and ∼43 nm in mean hydrodynamic diameter. The particles that were injected into tumors in mice (21 µg of gold) were homogeneously distributed within a tumor mass with no staining of the muscle tissue adjacent to the tumor. Up to 30% of the injected gold dose remained within the tumor one hour post-injection. The multispiked gold nanoparticles with a mean metallic core diameter of 146.0±50.4 nm and a mean hydrodynamic size of ~161 nm were prepared using ascorbic acid as a reducing agent and disk-like bicelles as a template. Only the presence of a soft template, like bicelles, ensured the appearance of spiked nanoparticles with resonance in the near infrared region. The irradiation of spiked gold nanoparticles by an 805 nm laser led to the time- and concentration-dependent increase of temperature. Both pHLIP ® and PEG coated gold spherical and multispiked nanoparticles might find application in radiation and thermal therapies of tumors.

Nanoparticle-Based Receptors Mimic Protein-Ligand Recognition.

PubMed

Riccardi, Laura; Gabrielli, Luca; Sun, Xiaohuan; De Biasi, Federico; Rastrelli, Federico; Mancin, Fabrizio; De Vivo, Marco

2017-07-13

The self-assembly of a monolayer of ligands on the surface of noble-metal nanoparticles dictates the fundamental nanoparticle's behavior and its functionality. In this combined computational-experimental study, we analyze the structure, organization, and dynamics of functionalized coating thiols in monolayer-protected gold nanoparticles (AuNPs). We explain how functionalized coating thiols self-organize through a delicate and somehow counterintuitive balance of interactions within the monolayer itself and with the solvent. We further describe how the nature and plasticity of these interactions modulate nanoparticle-based chemosensing. Importantly, we found that self-organization of coating thiols can induce the formation of binding pockets in AuNPs. These transient cavities can accommodate small molecules, mimicking protein-ligand recognition, which could explain the selectivity and sensitivity observed for different organic analytes in NMR chemosensing experiments. Thus, our findings advocate for the rational design of tailored coating groups to form specific recognition binding sites on monolayer-protected AuNPs.

Flexible fiber-reinforced composites with improved interfacial adhesion by mussel-inspired polydopamine and poly(methyl methacrylate) coating.

PubMed

Yi, Mi; Sun, Hongyang; Zhang, Hongcheng; Deng, Xuliang; Cai, Qing; Yang, Xiaoping

2016-01-01

To obtain a kind of light-curable fiber-reinforced composite for dental restoration, an excellent interfacial adhesion between the fiber and the acrylate resin matrix is quite essential. Herein, surface modification on glass fibers were carried out by coating them with poly(methyl methacrylate) (PMMA), polydopamine (PDA), or both. The PMMA or PDA coating was performed by soaking fibers in PMMA/acetone solution or dopamine aqueous solution. PDA/PMMA co-coated glass fibers were obtained by further soaking PDA-coated fibers in PMMA/acetone solution. These modified fibers were impregnated with bisphenol A glycidyl methacrylate (Bis-GMA)/triethylene glycol dimethacrylate (TEGDMA) (5:5, w/w) dental resin at a volume fraction of 75%, using unmodified fibers as reference. Light-cured specimens were submitted to evaluations including flexural properties, morphological observation, dynamic mechanical thermal analysis (DMTA) and pull-out test. In comparison with unmodified glass fibers, all the modified glass fibers showed enhancements in flexural strength and modulus of Bis-GMA/TEGDMA resin composites. Results of DMTA and pull-out tests confirmed that surface modification had significantly improved the interfacial adhesion between the glass fiber and the resin matrix. Particularly, the PDA/PMMA co-coated glass fibers displayed the most efficient reinforcement and the strongest interfacial adhesion due to the synergetic effects of PDA and PMMA. It indicated that co-coating method was a promising approach in modifying the interfacial compatibility between inorganic glass fiber and organic resin matrix. Copyright © 2015 Elsevier B.V. All rights reserved.

Preceramic Polymers for Use as Fiber Coatings

NASA Technical Reports Server (NTRS)

Heimann, P. J.; Hurwitz, F. I.; Wheeler, D.; Eldridge, J.; Baranwal, R.; Dickerson, R.

1996-01-01

Polymeric precursors to Si-C-O, SI-B-N and Si-C were evaluated for use as ceramic interfaces in ceramic matrix composites. Use of the preceramic polymers allows for easy dip coating of fibers from dilute solutions of a polymer, which are then pyrolyzed to obtain the ceramic. SCS-0 fibers (Textron Specialty Materials, Lowell, MA) were coated with polymers from three systems: polysilsesquioxanes, polyborosilazanes and polycarbosilanes. The polysilsesquioxane systems were shown to produce either silicon oxycarbide or silicon oxynitride, depending on the pyrolysis conditions, and demonstrated some promise in an RBSN (reaction-bonded silicon nitride) matrix model system. Polyborosilazanes were shown, in studies of bulk polymers, to give rise to oxidation resistant Si-B-N ceramics which remain amorphous to temperatures of 1600 C, and should therefore provide a low modulus interface. Polycarbosilanes produce amorphous carbon-rich Si-C materials which have demonstrated oxidation resistance.

Precipitation Coating of Monazite on Woven Ceramic Fibers: 1. Feasibility (Postprint)

DTIC Science & Technology

2007-02-01

08 Aug 2006. Paper contains color . 14. ABSTRACT Monazite coatings were deposited on woven cloths and tows of NextelTM 610 fibers by heterogeneous...by dissolving concentrated phosphoric acid ( Fish - er Scientific Co., Pittsburgh, PA) or a combination of lantha- num nitrate (Aldrich Chemical Co...Boccaccini, P. Karapappas, J. M. Marijuan, and C. Kaya, ‘‘ TiO2 Coat- ings on Silicon Carbide Fiber Substrates by Electrophoretic Deposition,’’ J.Mater. Sci

Coating of Carbon Fiber with Polyhedral Oligomeric Silsesquioxane (POSS) to Enhance Mechanical Properties and Durability of Carbon/Vinyl Ester Composites

PubMed Central

Mahfuz, Hassan; Powell, Felicia; Granata, Richard; Hosur, Mahesh; Khan, Mujib

2011-01-01

Our continuing quest to improve the performance of polymer composites under moist and saltwater environments has gained momentum in recent years with the reinforcement of inorganic nanoparticles into the polymer. The key to mitigate degradation of composites under such environments is to maintain the integrity of the fiber/matrix (F/M) interface. In this study, the F/M interface of carbon/vinyl ester composites has been modified by coating the carbon fiber with polyhedral oligomeric silsesquioxane (POSS). POSS is a nanostructured inorganic-organic hybrid particle with a cubic structure having silicon atoms at the core and linked to oxygen atoms. The advantage of using POSS is that the silicon atoms can be linked to a substituent that can be almost any chemical group known in organic chemistry. Cubic silica cores are ‘hard particles’ and are about 0.53 nm in diameter. The peripheral organic unit is a sphere of about 1–3 nm in diameter. Further, cubic structure of POSS remains intact during the polymerization process and therefore with appropriate functional groups, if installed on the fiber surface, would provide a stable and strong F/M interface. Two POSS systems with two different functional groups; namely, octaisobutyl and trisilanolphenyl have been investigated. A set of chemical and mechanical procedures has been developed to coat carbon fibers with POSS, and to fabricate layered composites with vinyl ester resin. Interlaminar shear and low velocity impact tests have indicated around 17–38% improvement in mechanical properties with respect to control samples made without the POSS coating. Saltwater and hygrothermal tests at various environmental conditions have revealed that coating with POSS reduces water absorption by 20–30% and retains the composite properties. PMID:28824160

Surface functionalization of dopamine coated iron oxide nanoparticles for various surface functionalities

NASA Astrophysics Data System (ADS)

Sherwood, Jennifer; Xu, Yaolin; Lovas, Kira; Qin, Ying; Bao, Yuping

2017-04-01

We present effective conjugation of four small molecules (glutathione, cysteine, lysine, and Tris(hydroxymethyl)aminomethane) onto dopamine-coated iron oxide nanoparticles. Conjugation of these molecules could improve the surface functionality of nanoparticles for more neutral surface charge at physiological pH and potentially reduce non-specific adsorption of proteins to nanoparticles surfaces. The success of conjugation was evaluated with dynamic light scattering by measuring the surface charge changes and Fourier transform infrared spectroscopy for surface chemistry analysis. The stability of dopamine-coated nanoparticles and the ability of conjugated nanoparticles to reduce the formation of protein corona were evaluated by measuring the size and charge of the nanoparticles in biological medium. This facile conjugation method opens up possibilities for attaching various surface functionalities onto iron oxide nanoparticle surfaces for biomedical applications.

Enhanced antibacterial nanocomposite mats by coaxial electrospinning of polycaprolactone fibers loaded with Zn-based nanoparticles.

PubMed

Prado-Prone, Gina; Silva-Bermudez, Phaedra; Almaguer-Flores, Argelia; García-Macedo, Jorge A; García, Victor I; Rodil, Sandra E; Ibarra, Clemente; Velasquillo, Cristina

2018-04-16

ZnO and Zn acetate nanoparticles were embedded in polycaprolactone coaxial-fibers and uniaxial-fibers matrices to develop potential antibacterial nanocomposite wound dressings (mats). Morphology, composition, wettability, crystallinity and fiber structure of mats were characterized. Antibacterial properties of mats were tested against E. coli and S. aureus by turbidity and MTT assays. The effect of UVA illumination (prior to bacteria inoculation) on mats' antibacterial activity was also studied. Results showed that a coaxial-fibers design maintained nanoparticles distributed in the outer-shell of fibers and, in general, enhanced the antibacterial effect of the mats, in comparison to conventional uniaxial-fibers mats. Results indicated that mats simultaneously inhibited planktonic and biofilm bacterial growth by, probably, two main antibacterial mechanisms; 1) release of Zn 2+ ions (mainly from Zn acetate nanoparticles) and 2) photocatalytic oxidative processes exerted by ZnO nanoparticles. Antibacterial properties of mats were significantly improved by coaxial-fibers design and exposure to UVA-light prior to bacteria inoculation. Copyright © 2018 Elsevier Inc. All rights reserved.

The Role of Dextran Coatings on the Cytotoxicity Properties of Ceria Nanoparticles Toward Bone Cancer Cells

NASA Astrophysics Data System (ADS)

Yazici, Hilal; Alpaslan, Ece; Webster, Thomas J.

2015-04-01

Cerium oxide nanoparticles have demonstrated great potential as antioxidant and radioprotective agents for nanomedicine applications especially for cancer therapy. The surface chemistry of nanoparticles is an important property that has a significant effect on their performance in biological applications including cancer diagnosis, cancer treatment, and bacterial infection. Recently, various nanosized cerium oxide particles with different types of polymer coatings have been developed to improve aqueous solubility and allow for surface functionalization for distinct applications. In this study, the role of ceria nanoparticles coated with dextran on the cytotoxicity properties of bone cancer cells was shown. Specifically, 0.1 M and 0.01 M dextran-coated, <5-nm ceria nanoparticles, were synthesized. The cytotoxicity of 0.1 M and 0.01 M dextran-coated ceria nanoparticles was evaluated against osteosarcoma cells. A change in cell viability was observed when treating osteosarcoma cells with 0.1 M dextran-coated ceria nanoparticles in the 250 -1000 μg/mL concentration range. In contrast, minimal toxicity to bone cancer cells was observed for the 0.01 M dextran coating after 3 days compared with the 0.1 M dextran coating. These results indicated that surface dextran functionalization had a positive impact on the cytotoxicity of cerium oxide nanoparticles against osteosarcoma cells.

On the origin of the visible light responsible for proton dose measurement using plastic optical fibers

NASA Astrophysics Data System (ADS)

Darafsheh, Arash; Taleei, Reza; Kassaee, Alireza; Finlay, Jarod C.

2017-03-01

We experimentally and by means of Monte Carlo simulations investigated the origin of the visible signal responsible for proton therapy dose measurement using bare plastic optical fibers. Experimentally, the fiber optic probe, embedded in tissue-mimicking plastics, was irradiated with a proton beam produced by a proton therapy cyclotron and the luminescence spectroscopy was performed by a CCD-coupled spectrograph to analyze the emission spectrum of the fiber tip. Monte Carlo simulations were performed using FLUKA Monte Carlo code to stochastically simulate radiation transport, ionizing radiation dose deposition, and optical emission of Čerenkov radiation. The spectroscopic study of proton-irradiated plastic fibers showed a continuous spectrum with shape different from that of Čerenkov radiation. The Monte Carlo simulations confirmed that the amount of the generated Čerenkov light does not follow the radiation absorbed dose in a medium. Our results show that the origin of the optical signal responsible for the proton dose measurement using bare optical fibers is not Čerenkov radiation. Our results point toward a connection between the scintillation of the plastic material of the fiber and the origin of the signal responsible for dose measurement.

Plastic fiber scintillator response to fast neutrons

NASA Astrophysics Data System (ADS)

Danly, C. R.; Sjue, S.; Wilde, C. H.; Merrill, F. E.; Haight, R. C.

2014-11-01

The Neutron Imaging System at NIF uses an array of plastic scintillator fibers in conjunction with a time-gated imaging system to form an image of the neutron emission from the imploded capsule. By gating on neutrons that have scattered from the 14.1 MeV DT energy to lower energy ranges, an image of the dense, cold fuel around the hotspot is also obtained. An unmoderated spallation neutron beamline at the Weapons Neutron Research facility at Los Alamos was used in conjunction with a time-gated imaging system to measure the yield of a scintillating fiber array over several energy bands ranging from 1 to 15 MeV. The results and comparison to simulation are presented.

Plastic fiber scintillator response to fast neutrons.

PubMed

Danly, C R; Sjue, S; Wilde, C H; Merrill, F E; Haight, R C

2014-11-01

The Neutron Imaging System at NIF uses an array of plastic scintillator fibers in conjunction with a time-gated imaging system to form an image of the neutron emission from the imploded capsule. By gating on neutrons that have scattered from the 14.1 MeV DT energy to lower energy ranges, an image of the dense, cold fuel around the hotspot is also obtained. An unmoderated spallation neutron beamline at the Weapons Neutron Research facility at Los Alamos was used in conjunction with a time-gated imaging system to measure the yield of a scintillating fiber array over several energy bands ranging from 1 to 15 MeV. The results and comparison to simulation are presented.

Magnetic field sensing based on tilted fiber Bragg grating coated with nanoparticle magnetic fluid

NASA Astrophysics Data System (ADS)

Yang, Dexing; Du, Lei; Xu, Zengqi; Jiang, Yajun; Xu, Jian; Wang, Meirong; Bai, Yang; Wang, Haiyan

2014-02-01

A magnetic field sensor based on a tilted fiber Bragg grating (TFBG) coated with magnetic fluid is proposed and demonstrated experimentally. The sensing element is made by injecting the magnetic fluid into a capillary tube which contains a TFBG. The resonant wavelengths of the cladding modes of TFBG shift by varying the magnetic field which is perpendicular to the axis of TFBG. The results indicate that the resonant wavelength shifts of the cladding modes show a nonlinear dependence on the magnetic field. As the magnetic field increases to 32 mT, the largest resonant wavelength shift reaches to 106 pm. Moreover, this sensor shows good repeatability when it is used for magnetic field sensing.

Au-coated 3-D nanoporous titania layer prepared using polystyrene-b-poly(2-vinylpyridine) block copolymer nanoparticles.

PubMed

Shin, Won-Jeong; Basarir, Fevzihan; Yoon, Tae-Ho; Lee, Jae-Suk

2009-04-09

New nanoporous structures of Au-coated titania layers were prepared by using amphiphilic block copolymer nanoparticles as a template. A 3-D template composed of self-assembled quaternized polystyrene-b-poly(2-vinylpyridine) (Q-PS-b-P2VP) block copolymer nanoparticles below 100 nm was prepared. The core-shell-type nanoparticles were well ordered three-dimensionally using the vertical immersion method on the substrate. The polar solvents were added to the polymer solution to prevent particle merging at 40 degrees C when considering the interaction between polymer nanoparticles and solvents. Furthermore, Au-coated PS-b-P2VP nanoparticles were prepared using thiol-capped Au nanoparticles (3 nm). The 3-D arrays with Au-coated PS-b-P2VP nanoparticles as a template contributed to the preparation of the nanoporous Au-coated titania layer. Therefore, the nanoporous Au-coated titania layer was fabricated by removing PS-b-P2VP block copolymer nanoparticles by oxygen plasma etching.

Textile fibers coated with carbon nanotubes for smart clothing applications

NASA Astrophysics Data System (ADS)

Lepak, Sandra; Lalek, Bartłomiej; Janczak, Daniel; Dybowska-Sarapuk, Łucja; Krzemiński, Jakub; Jakubowska, Małgorzata; Łekawa-Raus, Agnieszka

2017-08-01

Carbon nanomaterials: graphene, fullerenes and in particular carbon nanotubes (CNTs) are extremely interesting and extraordinary materials. It is mostly thanks to theirs unusual electrical and mechanical properties. Carbon nanotubes are increasingly examined to enable its usage in many fields of science and technology. It has been reported that there is a high possibility to use CNTs in electronics, optics, material engineering, biology or medicine. However, this material still interests and inspire scientists around the world and the list of different CNTs applications is constantly expanding. In this paper we are presenting a study on the possibility of application carbon nanotubes as a textile fiber coating for smart clothing applications. Various suspensions and pastes containing CNTs have been prepared as a possible coating onto textile fibers. Different application techniques have also been tested. Those techniques included painting with nanotube suspension, spray coating of suspensions and immersion. Following textile fibers were subject to tests: cotton, silk, polyester, polyamide and wool. Obtained composites materials were then characterized electrically by measuring the electrical resistance.

ZnO nanoparticles based fiber optic gas sensor

DOE Office of Scientific and Technical Information (OSTI.GOV)

Narasimman, S.; Sivacoumar, R.; Alex, Z. C.

In this work, ZnO nanoparticles were synthesized by simple aqueous chemical route method. The synthesized ZnO nanoparticles were characterized by X-ray diffraction and scanning electron microscope. The sensitivity of the nanoparticles was studied for different gases like acetone, ammonia and ethanol in terms of variation in spectral light intensity. The XRD and SEM analysis confirms the formation of hexagonal wurtzite structure with the grain size of 11.2 nm. The small cladding region of the optical fiber was replaced with the synthesized nanoparticles. The light spectrum was recorded for different gas concentrations. The synthesized nanoparticles showed high sensitivity towards ammonia in lowmore » ppm level and acetone in high ppm level.« less

Detection of Hydrofluoric Acid by a SiO2 Sol-Gel Coating Fiber-Optic Probe Based on Reflection-Based Localized Surface Plasmon Resonance

PubMed Central

Chen, I-Cherng; Lin, Shiu-Shiung; Lin, Tsao-Jen; Du, Je-Kang

2011-01-01

A novel fiber-optic probe based on reflection-based localized surface plasmon resonance (LSPR) was developed to quantify the concentration of hydrofluoric acid (HF) in aqueous solutions. The LSPR sensor was constructed with a gold nanoparticle-modified PMMA fiber, integrated with a SiO2 sol-gel coating. This fiber-sensor was utilized to assess the relationship between HF concentration and SiO2 sol-gel layer etching reduction. The results demonstrated the LSPR sensor was capable of detecting HF-related erosion of hydrofluoric acid solutions of concentrations ranging from 1% to 5% using Relative RI Change Rates. The development of the LSPR sensor constitutes the basis of a detector with significant sensitivity for practical use in monitoring HF solution concentrations. PMID:22319388

Nanostructured copper-coated solid-phase microextraction fiber for gas chromatographic analysis of dibutyl phthalate and diethylhexyl phthalate environmental estrogens.

PubMed

Feng, Juanjuan; Sun, Min; Bu, Yanan; Luo, Chuannan

2015-01-01

A novel nanostructured copper-based solid-phase microextraction fiber was developed and applied for determining the two most common types of phthalate environmental estrogens (dibutyl phthalate and diethylhexyl phthalate) in aqueous samples, coupled to gas chromatography with flame ionization detection. The copper film was coated onto a stainless-steel wire via an electroless plating process, which involved a surface activation process to improve the surface properties of the fiber. Several parameters affecting extraction efficiency such as extraction time, extraction temperature, ionic strength, desorption temperature, and desorption time were optimized by a factor-by-factor procedure to obtain the highest extraction efficiency. The as-established method showed wide linear ranges (0.05-250 μg/L). Precision of single fiber repeatability was <7.0%, and fiber-to-fiber repeatability was <10%. Limits of detection were 0.01 μg/L. The proposed method exhibited better or comparable extraction performance compared with commercial and other lab-made fibers, and excellent thermal stability and durability. The proposed method was applied successfully for the determination of model analytes in plastic soaking water. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Polymer blends used for the aqueous coating of solid dosage forms: importance of the type of plasticizer.

PubMed

Lecomte, F; Siepmann, J; Walther, M; MacRae, R J; Bodmeier, R

2004-09-14

The aim of this study was to investigate the importance of the type of plasticizer in polymer blends used for the coating of solid dosage forms, comparing a lipophilic and a hydrophilic plasticizer (dibutyl sebacate (DBS) and triethyl citrate (TEC)). In vitro drug release from propranolol hydrochloride (propranolol HCl)-loaded pellets coated with blends of ethyl cellulose (EC) and Eudragit L (100:0, 75:25, 50:50, 25:75 and 0:100 w/w) was investigated at low as well as at high pH. To better understand the underlying mass transport mechanisms, the physicochemical properties of the film coatings (e.g. mechanical resistance, water uptake and dry weight loss behavior) were determined. Interestingly, drug release strongly depended on the type of plasticizer. Importantly, not only the slope but also the shape of the release curves was affected, indicating that the chemical nature of the plasticizer plays a major role for the underlying drug release mechanisms. Diffusion through the intact polymer coatings and/or through water-filled cracks was found to be dominating for the control of drug release. The relative importance of these pathways strongly depended on the polymer blend ratio and type of plasticizer. In contrast to DBS, TEC rapidly leached out of the coatings, resulting in decreasing mechanical resistances of the films and, thus, facilitated crack formation. In addition, the hydrophilicity of the plasticizer significantly affected the water uptake behavior of the film coatings and, hence, changes in the coatings' toughness and drug permeability. Also the relative affinity of the plasticizer to the different polymers was found to be of significance. In contrast to TEC, DBS has a higher affinity to EC than to Eudragit L, resulting in potential redistributions of this plasticizer within the polymeric systems and changes in the release profiles during storage. Importantly, these effects could be avoided with appropriate curing conditions and preparation techniques for

Potassium methyl siliconate-treated pulp fibers and their effects on wood plastic composites: Water sorption and dimensional stability

Treesearch

Cheng Piao; Zhiyong Cai; Nicole M. Stark; Charles J. Monlezun

2013-01-01

Potassium methyl siliconate (PMS) was investigated as a new nano modifier of wood fiber and wood flour to improve the compatibility between the fiber/flour and the plastic matrix in fiber reinforced plastic composites. Before injection molding, bleached and brown pulp fibers and mixed species wood flour were pretreated in PMS solutions. The morphology of the treated...

In vitro antiplasmodial activity of PDDS-coated metal oxide nanoparticles against Plasmodium falciparum

NASA Astrophysics Data System (ADS)

Jacob Inbaneson, Samuel; Ravikumar, Sundaram

2013-06-01

Malaria is the most important parasitic disease, leading to annual death of about one million people and the Plasmodium falciparum develops resistant to well-established antimalarial drugs. The newest antiplasmodial drug from metal oxide nanoparticles helps in addressing this problem. Commercial nanoparticles such as Fe3O4, MgO, ZrO2, Al2O3 and CeO2 coated with PDDS and all the coated and non-coated nanoparticles were screened for antiplasmodial activity against P. falciparum. The Al2O3 nanoparticles (71.42 ± 0.49 μg ml-1) showed minimum level of IC50 value and followed by MgO (72.33 ± 0.37 μg ml-1) and Fe3O4 nanoparticles (77.23 ± 0.42 μg ml-1). The PDDS-Fe3O4 showed minimum level of IC50 value (48.66 ± 0.45 μg ml-1), followed by PDDS-MgO (60.28 ± 0.42 μg ml-1) and PDDS-CeO2 (67.06 ± 0.61 μg ml-1). The PDDS-coated metal oxide nanoparticles showed superior antiplasmodial activity than the non-PDDS-coated metal oxide nanoparticles. Statistical analysis reveals that, significant in vitro antiplasmodial activity ( P < 0.05) was observed between the concentrations and time of exposure. The chemical injury to erythrocytes showed no morphological changes in erythrocytes by the nanoparticles after 48 h of incubation. It is concluded from the present study that, the PDDS-Fe3O4 showed good antiplasmodial activity and it might be used for the development of antiplasmodial drugs.

Simultaneous hyperthermia and doxorubicin delivery from polymer-coated magnetite nanoparticles

NASA Astrophysics Data System (ADS)

Iglesias, G. R.; Delgado, A. V.; González-Caballero, F.; Ramos-Tejada, M. M.

2017-06-01

In this work, the hyperthermia response, (i.e., heating induced by an externally applied alternating magnetic field) and the simultaneous release of an anti-cancer drug (doxorubicin) by polymer-coated magnetite nanoparticles have been investigated. After describing the setup for hyperthermia measurements in suspensions of magnetic nanoparticles, the hyperthermia (represented by the rate of suspension heating and, ultimately, by the specific absorption rate or SAR) of magnetite nanoparticles (both bare and polymer-coated as drug nanocarriers) is discussed. The effect of the applied ac magnetic field on doxorubicin release is also studied, and it is concluded that the field does not interfere with the release process, demonstrating the double functionality of the investigated particles.

Silica Nanoparticles Functionalized with Zwitterionic Sulfobetaine Siloxane for Application as a Versatile Antifouling Coating System.

PubMed

Knowles, Brianna R; Wagner, Pawel; Maclaughlin, Shane; Higgins, Michael J; Molino, Paul J

2017-06-07

The growing need to develop surfaces able to effectively resist biological fouling has resulted in the widespread investigation of nanomaterials with potential antifouling properties. However, the preparation of effective antifouling coatings is limited by the availability of reactive surface functional groups and our ability to carefully control and organize chemistries at a materials' interface. Here, we present two methods of preparing hydrophilic low-fouling surface coatings through reaction of silica-nanoparticle suspensions and predeposited silica-nanoparticle films with zwitterionic sulfobetaine (SB). Silica-nanoparticle suspensions were functionalized with SB across three pH conditions and deposited as thin films via a simple spin-coating process to generate hydrophilic antifouling coatings. In addition, coatings of predeposited silica nanoparticles were surface functionalized via exposure to zwitterionic solutions. Quartz crystal microgravimetry with dissipation monitoring was employed as a high throughput technique for monitoring and optimizing reaction to the silica-nanoparticle surfaces. Functionalization of nanoparticle films was rapid and could be achieved over a wide pH range and at low zwitterion concentrations. All functionalized particle surfaces presented a high degree of wettability and resulted in large reductions in adsorption of bovine serum albumin protein. Particle coatings also showed a reduction in adhesion of fungal spores (Epicoccum nigrum) and bacteria (Escherichia coli) by up to 87 and 96%, respectively. These results indicate the potential for functionalized nanosilicas to be further developed as versatile fouling-resistant coatings for widespread coating applications.

Effects of functional groups and ionization on the structure of alkanethiol coated gold nanoparticles

NASA Astrophysics Data System (ADS)

Bolintineanu, Dan S.; Lane, J. Matthew D.; Grest, Gary S.

2013-03-01

We report fully atomistic molecular dynamics simulations of alkanethiol coated gold nanoparticles solvated in water and decane. The structure of the coatings is analyzed as a function of various functional end groups, including amine and carboxyl groups in different neutralization states. We study the effects of charge in the end groups for two different chain lengths (10 and 18 carbons) and different counterions (mono- and divalent). For the longer alkanes we find significant local phase segregation of chains on the nanoparticle surface, which results in highly asymmetric coating structures. In general, the charged end groups attenuate this effect by enhancing the water solubility of the nanoparticles. Based on the coating structures and density profiles, we can qualitatively infer the overall solubility of the nanoparticles. The asymmetry in the alkanethiol coatings is also likely to have a significant effect on aggregation behavior. More importantly, our simulations suggest the ability to modulate end group charge states (e.g. by changing the pH of the solution) in order to control coating structure, and therefore control solubility and aggregation behavior.

Gold Coating of Fiber Tips in Near-Field Scanning Optical Microscopy

NASA Technical Reports Server (NTRS)

Vikram, Chandra S.; Witherow, William K.

2000-01-01

We report what is believed to be the first experimental demonstration of gold coating by a chemical baking process on tapered fiber tips used in near-field scanning optical microscopy. Many tips can be simultaneously coated.

Continuous fiber reinforced mesh bond coat for environmental barrier coating system

DOEpatents

Zhang, James; Das, Rupak; Roberts III, Herbert Chidsey; Delvaux, John McConnell

2017-09-26

A gas turbine blade may have a bond coat applied to its surface. A porous substrate may be applied to the bond layer and one or more protective layers may be applied to the bond layer such that the fiber mesh is embedded between the bond layer and the protective layer to prevent creep.

Carbon fiber CVD coating by carbon nanostructured for space materials protection against atomic oxygen

NASA Astrophysics Data System (ADS)

Pastore, Roberto; Bueno Morles, Ramon; Micheli, Davide

2016-07-01

adhesion and durability in the environment. Though these coatings are efficient in protecting polymer composites, their application imposes severe constraints. Their thermal expansion coefficients may differ markedly from those of polymer composite substrates: as a result, cracks develop in the coatings on thermal cycling and AO can penetrate through them to the substrate. In addition to the technicalities of forming an effective barrier, such factors as cost, convenience of application and ease of repair are important considerations in the selection of a coating for a particular application. The latter issues drive the aerospace research toward the development of novel light composite materials, like the so called polymer nanocomposites, which are materials with a polymer matrix and a filler with at least one dimension less than 100 nanometers. Current interest in nanocomposites has been generated and maintained because nanoparticle-filled polymers exhibit unique combinations of properties not achievable with traditional composites. These combinations of properties can be achieved because of the small size of the fillers, the large surface area the fillers provide, and in many cases the unique properties of the fillers themselves. In particular, the carbon fiber-based polymeric composite materials are the basic point of interest: the aim of the present study is to find new solution to produce carbon fiber-based composites with even more upgraded performances. One intriguing strategy to tackle such an issue has been picked out in the coupling between the carbon fibers and the carbon nanostructures. That for two main reasons: first, carbon nanostructures have shown fancy potentialities for any kind of technological applications since their discovery, second, the chemical affinity between fiber and nanostructure (made of the same element) should be a likely route to approach the typical problems due to thermo-mechanical compatibility. This work is joined in such framework

Preparation and characterization of polydimethylsiloxane/poly(vinylalcohol) coated solid phase microextraction fibers using sol-gel technology.

PubMed

Lopes, Alexandre Leite; Augusto, Fabio

2004-11-12

The applicability of a composite composed of polydimethylsiloxane (PDMS) and poly(vinyl alcohol) (PDMS/PVA) as coating sorbent for SPME fibers is demonstrated here. Fused silica (FS) fibers were coated with PDMS/PVA composite through a sol-gel process, using methyltrimethoxysilane as reticulating agent. The chemical and physical properties of the sol-gel PDMS/PVA composite were determined by infrared spectroscopy and thermogravimetric analysis. Electron scanning microscopy of the prepared fibers, showed that the coating obtained was highly microporous, having a thickness of approximately 5 microm. The fibers were tested for the headspace extraction of several organic compounds (o-xylene, naphthalene, ethyl caprate, p-chlorotoluene and PCB) prior to gas chromatographic analysis. The extractive capacity of the PDMS/PVA coating was found to be superior to that of pure conventional PDMS fibers.

A novel Ag catalyzation process using swelling impregnation method for electroless Ni deposition on Kevlar® fiber

NASA Astrophysics Data System (ADS)

Pang, Hongwei; Bai, Ruicheng; Shao, Qinsi; Gao, Yufang; Li, Aijun; Tang, Zhiyong

2015-12-01

A novel Ag catalyzation process using swelling impregnation pretreatment method was developed for electroless nickel (EN) deposition on Kevlar fiber. Firstly, the fiber was immersed into an aqueous dimethylsulfoxide (DMSO) solution of silver nitrate to impart silver nitrate into the inner part of the fiber near the surface. Subsequently silver nitrate was reduced to metal silver nanoparticles on the fiber surface by treatment with aqueous solution of sodium borohydride. After electroless plating, a dense and homogeneous nickel coating was obtained on the fiber surface. The silver nanoparticles formed at the fiber surface functioned as a catalyst for electroless deposition as well as an anchor for the plated layer. The study also revealed that the incorporation of surfactant sodium dodecyl sulfate (SDS) in electroless nickel plating bath can enhance the adhesion strength of EN layer with the fiber surface and minimize the surface roughness of the EN coating. The Ni plated Kevlar fiber possessed excellent corrosion resistance and high tensile strength.

Stability of polyvinyl alcohol-coated biochar nanoparticles in brine

NASA Astrophysics Data System (ADS)

Griffith, Christopher; Daigle, Hugh

2017-01-01

This paper reports on the dispersion stability of 150 nm polyvinyl alcohol coated biochar nanoparticles in brine water. Biochar is a renewable, carbon based material that is of significant interest for enhanced oil recovery operations primarily due to its wide ranging surface properties, low cost of synthesis, and low environmental toxicity. Nanoparticles used as stabilizing agents for foams (and emulsions) or in nanofluids have emerged as potential alternatives to surfactants for subsurface applications due to their improved stability at reservoir conditions. If, however, the particles are not properly designed, they are susceptible to aggregation because of the high salinity brines typical of oil and gas reservoirs. Attachment of polymers to the nanoparticle surface, through covalent bonds, provides steric stabilization, and is a necessary step. Our results show that as the graft density of polyvinyl alcohol increases, so too does the stability of nanoparticles in brine solutions. A maximum of 34 wt% of 50,000 Da polyvinyl alcohol was grafted to the particle surface, and the size of the particles was reduced from 3500 nm (no coating) to 350 nm in brine. After 24 h, the particles had a size of 500 nm, and after 48 h completely aggregated. 100,000 Da PVA coated at 24 wt% on the biochar particles were stable in brine for over 1 month with no change in mean particle size of 330 nm.

Evaluation of E. coli inhibition by plain and polymer-coated silver nanoparticles.

PubMed

Ashmore, D'Andrea; Chaudhari, Atul; Barlow, Brandi; Barlow, Brett; Harper, Talia; Vig, Komal; Miller, Michael; Singh, Shree; Nelson, Edward; Pillai, Shreekumar

2018-01-01

Escherichia coli causes various ailments such as septicemia, enteritis, foodborne illnesses, and urinary tract infections which are of concern in the public health field due to antibiotic resistance. Silver nanoparticles (AgNP) are known for their biocompatibility and antibacterial activity, and may prove to be an alternative method of treatment, especially as wound dressings. In this study, we compared the antibacterial efficacy of two polymer-coated silver nanoparticles either containing 10% Ag (Ag 10% + Polymer), or 99% Ag (AgPVP) in relation to plain uncoated silver nanoparticles (AgNP). Atomic force microscopy was used to characterize the nanoparticles, and their antibacterial efficacy was compared by the minimum inhibitory concentration (MIC) and bacterial growth curve assays, followed by molecular studies using scanning electron microscopy (SEM) and (qRT- PCR). AgNP inhibited the growth of E. coli only at 0.621 mg/mL, which was double the concentration required for both coated nanoparticles (0.312 mg/mL). Similarly, bacterial growth was impeded as early as 8 h at 0.156 mg/mL of both coated nanoparticles as compared to 0.312 mg/mL for plain AgNP. SEM data showed that nanoparticles damaged the cell membrane, resulting in bacterial cell lysis, expulsion of cellular contents, and complete disintegration of some cells. The expression of genes associated with the TCA cycle (aceF and frdB) and amino acid metabolism (gadB, metL, argC) were substantially downregulated in E. coli treated with nanoparticles. The reduction in the silver ion (Ag+) concentration of polymer-coated AgNP did not affect their antibacterial efficacy against E. coli.

Preparation, characterization and dynamical mechanical properties of dextran-coated iron oxide nanoparticles (DIONPs).

PubMed

Can, Hatice Kaplan; Kavlak, Serap; ParviziKhosroshahi, Shahed; Güner, Ali

2018-03-01

Dextran-coated iron oxide nanoparticles (DIONPs) with appropriate surface chemistry exhibit many interesting properties that can be exploited in a variety of biomedical applications such as magnetic resonance imaging (MRI) contrast enhancement, tissue repair, hyperthermia, drug delivery and in cell separation. This paper reports the experimental detail for preparation, characterization and investigation of thermal and dynamical mechanical characteristics of the dextran-coated Fe 3 O 4 magnetic nanoparticles. In our work, DIONPs were prepared in a 1:2 ratio of Fe(II) and Fe(III) salt in the HCl solution with NaOH at given temperature. The obtained dextran-coated iron-oxide nanoparticles structure-property correlation was characterized by spectroscopic methods; attenuated total reflectance-Fourier transform infrared spectroscopy (ATR-FTIR) and XRD. Coating dextran on the iron-oxide proof of important peaks can be seen from the ATR-FTIR. Dramatic crystallinity increment can be observed from the XRD pattern of the iron-oxide dextran nanoparticles. The thermal analysis was examined by differential scanning calorimetry (DSC), thermal gravimetric analysis (TGA) and differential thermal analysis (DTA). Dynamical mechanical properties of dextran nanoparticles were analysed by dynamic mechanical analysis (DMA). Thermal stability of the iron oxide dextran nanoparticles is higher than that of the dextran.

Gold nanoparticle-based plasmonic random fiber laser

NASA Astrophysics Data System (ADS)

Hu, Zhijia; Liang, Yunyun; Xie, Kang; Gao, Pengfei; Zhang, Douguo; Jiang, Haiming; Shi, Fan; Yin, Leicheng; Gao, Jiangang; Ming, Hai; Zhang, Qijin

2015-03-01

We have reported the realization of a plasmonic random fiber laser based on the localized surface plasmonic resonance of gold nanoparticles (NPs) in the liquid core optical fiber. The liquid core material contains a dispersive solution of gold NPs and laser dye pyrromethene 597 in toluene. It was experimentally proved that the fluorescence quenching of the dye is restrained in the optical fiber, which is considered one of the main sources of loss in the traditional laser system. Meanwhile, the random lasing can be more easily obtained in the random laser system with more overlap between the plasmonic resonance of the gold NPs and the photoluminescence spectrum of the dye molecules.

Temperature-Triggered Protein Adsorption on Polymer-Coated Nanoparticles in Serum.

PubMed

Koshkina, Olga; Lang, Thomas; Thiermann, Raphael; Docter, Dominic; Stauber, Roland H; Secker, Christian; Schlaad, Helmut; Weidner, Steffen; Mohr, Benjamin; Maskos, Michael; Bertin, Annabelle

2015-08-18

The protein corona, which forms on the nanoparticle's surface in most biological media, determines the nanoparticle's physicochemical characteristics. The formation of the protein corona has a significant impact on the biodistribution and clearance of nanoparticles in vivo. Therefore, the ability to influence the formation of the protein corona is essential to most biomedical applications, including drug delivery and imaging. In this study, we investigate the protein adsorption on nanoparticles with a hydrodynamic radius of 30 nm and a coating of thermoresponsive poly(2-isopropyl-2-oxazoline) in serum. Using multiangle dynamic light scattering (DLS) we demonstrate that heating of the nanoparticles above their phase separation temperature induces the formation of agglomerates, with a hydrodynamic radius of 1 μm. In serum, noticeably stronger agglomeration occurs at lower temperatures compared to serum-free conditions. Cryogenic transmission electron microscopy (cryo-TEM) revealed a high packing density of agglomerates when serum was not present. In contrast, in the presence of serum, agglomerated nanoparticles were loosely packed, indicating that proteins are intercalated between them. Moreover, an increase in protein content is observed upon heating, confirming that protein adsorption is induced by the alteration of the surface during phase separation. After cooling and switching the surface back, most of the agglomerates were dissolved and the main fraction returned to the original size of approximately 30 nm as shown by asymmetrical flow-field flow fractionation (AF-FFF) and DLS. Furthermore, the amounts of adsorbed proteins are similar before and after heating the nanoparticles to above their phase-separation temperature. Overall, our results demonstrate that the thermoresponsivity of the polymer coating enables turning the corona formation on nanoparticles on and off in situ. As the local heating of body areas can be easily done in vivo, the thermoresponsive

Stress transfer in microdroplet tensile test: PVC-coated and uncoated Kevlar-29 single fiber

NASA Astrophysics Data System (ADS)

Zhenkun, Lei; Quan, Wang; Yilan, Kang; Wei, Qiu; Xuemin, Pan

2010-11-01

The single fiber/microdroplet tensile test is applied for evaluating the interfacial mechanics between a fiber and a resin substrate. It is used to investigate the influence of a polymer coating on a Kevlar-29 fiber surface, specifically the stress transfer between the fiber and epoxy resin in a microdroplet. Unlike usual tests, this new test ensures a symmetrical axial stress on the embedded fiber and reduces the stress singularity that appears at the embedded fiber entry. Using a homemade loading device, symmetrical tensile tests are performed on a Kevlar-29 fiber with or without polyvinylchloride (PVC) coating, the surface of which is in contact with two epoxy resin microdroplets during curing. Raman spectra on the embedded fiber are recorded by micro-Raman Spectroscopy under different strain levels. Then they are transformed to the distributions of fiber axis stress based on the relationship between stress and Raman shift. The Raman results reveal that the fiber axial stresses increase with the applied loads, and the antisymmetric interfacial shear stresses, obtained by a straightforward balance of shear-to-axial forces argument, lead to the appearance of shear stress concentrations at a distance to the embedded fiber entry. The load is transferred from the outer fiber to the embedded fiber in the epoxy microdroplet. As is observed by scanning electronic microscopy (SEM), the existence of a flexible polymer coating on the fiber surface reduces the stress transfer efficiency.

Wear mechanisms of the biotribological nanocomposite a-C : H coatings implanted by metallic nanoparticles.

PubMed

Major, L; Janusz, M; Lackner, J M; Kot, M; Dyner, M; Major, B

2017-10-01

Recently, to reduce the residual stress and increase the mechanical properties of a-C:H coatings, metallic nanoparticles have been implanted into their structure. In the present work, to improve the properties of the coating, metallic nanoparticles, including Cu, Nb, Ta, Zr, AgPt and Ag, were inserted into the a-C:H structure. The applied biological and mechanical analysis allowed the optimal biotribological parameters to be indicated for the potential application as protective coatings for metallic medical tools. Wear mechanisms operating at the small length of the designed biotribological coating, such as a-C:H implanted by Zr nanoparticles, were studied by means of transmission electron microscopy (TEM). The TEM analysis confirmed very good coating adhesion to the metallic substrate. © 2017 The Authors Journal of Microscopy © 2017 Royal Microscopical Society.

Nanoindentation study of electrodeposited Ag thin coating: An inverse calculation of anisotropic elastic-plastic properties

DOE Office of Scientific and Technical Information (OSTI.GOV)

Cheng, Guang; Sun, Xin; Wang, Yuxin

A new inverse method was proposed to calculate the anisotropic elastic-plastic properties (flow stress) of thin electrodeposited Ag coating utilizing nanoindentation tests, previously reported inverse method for isotropic materials and three-dimensional (3-D) finite element analyses (FEA). Indentation depth was ~4% of coating thickness (~10 μm) to avoid substrate effect and different indentation responses were observed in the longitudinal (L) and the transverse (T) directions. The estimated elastic-plastic properties were obtained in the newly developed inverse method by matching the predicted indentation responses in the L and T directions with experimental measurements considering indentation size effect (ISE). The results were validatedmore » with tensile flow curves measured from free-standing (FS) Ag film. The current method can be utilized to characterize the anisotropic elastic-plastic properties of coatings and to provide the constitutive properties for coating performance evaluations.« less

Carboxylated SiO2-coated α-Fe nanoparticles: towards a versatile platform for biomedical applications.

PubMed

Kohara, Kaori; Yamamoto, Shinpei; Seinberg, Liis; Murakami, Tatsuya; Tsujimoto, Masahiko; Ogawa, Tetsuya; Kurata, Hiroki; Kageyama, Hiroshi; Takano, Mikio

2013-03-28

Carboxylated SiO2-coated α-Fe nanoparticles have been successfully prepared via CaH2-mediated reduction of SiO2-coated Fe3O4 nanoparticles followed by surface carboxylation. These α-Fe-based nanoparticles, which are characterized by ease of coating with additional functional groups, a large magnetization of 154 emu per g-Fe, enhanced corrosion resistivity, excellent aqueous dispersibility, and low cytotoxicity, have potential to be a versatile platform in biomedical applications.

Fiber-optic anemometer based on single-walled carbon nanotube coated tilted fiber Bragg grating.

PubMed

Zhang, Yang; Wang, Fang; Liu, Zigeng; Duan, Zhihui; Cui, Wenli; Han, Jie; Gu, Yiying; Wu, Zhenlin; Jing, Zhenguo; Sun, Changsen; Peng, Wei

2017-10-02

In this work, a novel and simple optical fiber hot-wire anemometer based on single-walled carbon nanotubes (SWCNTs) coated tilted fiber Bragg grating (TFBG) is proposed and demonstrated. For the hot-wire wind speed sensor design, TFBG is an ideal in-fiber sensing structure due to its unique features. It is utilized as both light coupling and temperature sensing element without using any geometry-modified or uncommon fiber, which simplifies the sensor structure. To further enhance the thermal conversion capability, SWCNTs are coated on the surface of the TFBG instead of traditional metallic materials, which have excellent thermal characteristics. When a laser light is pumped into the sensor, the pump light propagating in the core will be easily coupled into cladding of the fiber via the TFBG and strongly absorbed by the SWCNTs thin film. This absorption acts like a hot-wire raising the local temperature of the fiber, which is accurately detected by the TFBG resonance shift. In the experiments, the sensor's performances were investigated and controlled by adjusting the inherent angle of the TFBG, the thickness of SWCNTs film, and the input power of the pump laser. It was demonstrated that the developed anemometer exhibited significant light absorption efficiency up to 93%, and the maximum temperature of the local area on the fiber was heated up to 146.1°C under the relatively low pump power of 97.76 mW. The sensitivity of -0.3667 nm/(m/s) at wind speed of 1.0 m/s was measured with the selected 12° TFBG and 1.6 μm film.

Effects of oleic acid surface coating on the properties of nickel ferrite nanoparticles/PLA composites.

PubMed

Yin, Hong; Chow, Gan-Moog

2009-11-01

Nickel ferrite nanoparticles with or without oleic acid surface coating were mixed with poly(D,L-lactide) (PLA) by double emulsion method. If the nanoparticles were prepared without oleic acid coating, they adsorbed on the PLA surface. If the nanoparticles were coated with oleic acid, they could be readily encapsulated within the PLA microspheres. A slight depression in glass transition temperature was found in all composites and it could be related to the interfacial energies between nanoparticles and PLA. Optimum mixed composite was achieved by reducing interfacial energy. However, loading capacity was limited in this composite. Increasing the amount of nickel ferrite nanoparticles was not useful to increase loading capacity. Cytotoxicity of the composite decreased significantly when nickel ferrite nanoparticles were effectively encapsulated in PLA microspheres. (c) 2008 Wiley Periodicals, Inc.

Potential of silver nanoparticle-coated polyurethane foam as an antibacterial water filter.

PubMed

Jain, Prashant; Pradeep, T

2005-04-05

Silver nanoparticles can be coated on common polyurethane (PU) foams by overnight exposure of the foams to nanoparticle solutions. Repeated washing and air-drying yields uniformly coated PU foam, which can be used as a drinking water filter where bacterial contamination of the surface water is a health risk. Nanoparticles are stable on the foam and are not washed away by water. Morphology of the foam was retained after coating. The nanoparticle binding is due to its interaction with the nitrogen atom of the PU. Online tests were conducted with a prototypical water filter. At a flow rate of 0.5 L/min, in which contact time was of the order of a second, the output count of Escherichia coli was nil when the input water had a bacterial load of 10(5) colony-forming units (CFU) per mL. Combined with the low cost and effectiveness in its applications, the technology may have large implications to developing countries. Copyright (c) 2005 Wiley Periodicals, Inc.

Nanostructural evolution during emission of CsI-coated carbon fiber cathodes

NASA Astrophysics Data System (ADS)

Drummy, Lawrence F.; Apt, Scott; Shiffler, Don; Golby, Ken; LaCour, Matt; Maruyama, Benji; Vaia, Richard A.

2010-06-01

Carbon-based nanofiber and microfiber cathodes exhibit very low voltages for the onset of electron emission, and thus provide exciting opportunities for applications ranging from high power microwave sources to field emission displays. CsI coatings have been experimentally shown to lower the work function for emission from the fiber tips, although little is known about the microstructure of the fibers themselves in their as-received state, after coating with CsI, or after being subjected to high voltage cycling. Longitudinal cross sections of the original, unused CsI-coated fibers produced by focused ion beam lift-out revealed a nanostructured graphitic core surrounded by an amorphous carbon shell with submicron sized islands of crystalline CsI on the outer surface. Aberration-corrected high resolution electron microscopy (HREM) of the fiber core achieved 0.10 nm resolution, with the graphite (200) clearly visible in digital fast Fourier transformations of the 2-4 nm highly ordered graphitic domains. As the cathode fibers are cycled at high voltage, HREM demonstrates that the graphitic ordering of the core increases with the number of cycles, however the structure and thickness of the amorphous carbon layer remains unchanged. These results are consistent with micro-Raman measurements of the fiber disordered/graphitic (D/G) band ratios. After high voltage cycling, a uniform ˜100 nm film at the fiber tip was evident in both bright field transmission electron microscopy (TEM) and high angle annular dark field scanning TEM (STEM). Low-dose electron diffraction techniques confirmed the amorphous nature of this film, and STEM with elemental mapping via x-ray energy dispersive spectroscopy indicates this layer is composed of CsIO. The oxidative evolution of tip composition and morphology due to impurities in the chamber, along with increased graphitization of the fiber core, contributes to changes in emission behavior with cycling.

Preparation and characterization of chemically functionalized silica-coated magnetic nanoparticles as a DNA separator.

PubMed

Kang, Kiho; Choi, Jinsub; Nam, Joong Hee; Lee, Sang Cheon; Kim, Kyung Ja; Lee, Sang-Won; Chang, Jeong Ho

2009-01-15

The work describes a simple and convenient process for highly efficient and direct DNA separation with functionalized silica-coated magnetic nanoparticles. Iron oxide magnetic nanoparticles and silica-coated magnetic nanoparticles were prepared uniformly, and the silica coating thickness could be easily controlled in a range from 10 to 50 nm by changing the concentration of silica precursor (TEOS) including controlled magnetic strength and particle size. A change in the surface modification on the nanoparticles was introduced by aminosilanization to enhance the selective DNA separation resulting from electrostatic interaction. The efficiency of the DNA separation was explored via the function of the amino-group numbers, particle size, the amount of the nanoparticles used, and the concentration of NaCl salt. The DNA adsorption yields were high in terms of the amount of triamino-functionalized nanoparticles used, and the average particle size was 25 nm. The adsorption efficiency of aminofunctionalized nanoparticles was the 4-5 times (80-100%) higher compared to silica-coated nanoparticles only (10-20%). DNA desorption efficiency showed an optimum level of over 0.7 M of the NaCl concentration. To elucidate the agglomeration of nanoparticles after electrostatic DNA binding, the Guinier plots were calculated from small-angle X-ray diffractions in a comparison of the results of energy diffraction TEM and confocal laser scanning microscopy. Additionally, the direct separation of human genomic DNA was achieved from human saliva and whole blood with high efficiency.

Wear resistance of thick diamond like carbon coatings against polymeric materials used in single screw plasticizing technology

NASA Astrophysics Data System (ADS)

Zitzenbacher, G.; Liu, K.; Forsich, C.; Heim, D.

2015-05-01

Wear on the screw and barrel surface accompany polymer single screw plasticizing technology from the beginning. In general, wear on screws can be reduced by using nitrided steel surfaces, fused armour alloys on the screw flights and coatings. However, DLC-coatings (Diamond Like Carbon) comprise a number of interesting properties such as a high hardness, a low coefficient of friction and an excellent corrosion resistance due to their amorphous structure. The wear resistance of about 50 µm thick DLC-coatings against polyamide 6.6, polybutylene terephthalate and polypropylene is investigated in this paper. The tribology in the solids conveying zone of a single screw extruder until the beginning of melting is evaluated using a pin on disc tribometer and a so called screw tribometer. The polymeric pins are pressed against coated metal samples using the pin on disc tribometer and the tests are carried out at a defined normal force and sliding velocity. The screw tribometer is used to perform tribological experiments between polymer pellets and rotating coated metal shafts simulating the extruder screw. Long term experiments were performed to evaluate the wear resistance of the DLC-coating. A reduction of the coefficient of friction can be observed after a frictional distance of about 20 kilometers using glass fibre reinforced polymeric materials. This reduction is independent on the polymer and accompanied by a black layer on the wear surface of the polymeric pins. The DLC-coated metal samples show an up to 16 µm deep wear track after the 100 kilometer test period against the glass fiber filled materials only.

Analytical, Numerical and Experimental Examination of Reinforced Composites Beams Covered with Carbon Fiber Reinforced Plastic

NASA Astrophysics Data System (ADS)

Kasimzade, A. A.; Tuhta, S.

2012-03-01

In the article, analytical, numerical (Finite Element Method) and experimental investigation results of beam that was strengthened with fiber reinforced plastic-FRP composite has been given as comparative, the effect of FRP wrapping number to the maximum load and moment capacity has been evaluated depending on this results. Carbon FRP qualitative dependences have been occurred between wrapping number and beam load and moment capacity for repair-strengthen the reinforced concrete beams with carbon fiber. Shown possibilities of application traditional known analysis programs, for the analysis of Carbon Fiber Reinforced Plastic (CFRP) strengthened structures.

Improved coating for silica fiber based ceramic Reusable Surface Insulation (CRSI)

NASA Technical Reports Server (NTRS)

Ormiston, T. J.

1974-01-01

A series of coatings was developed for the space shuttle type silica fiber insulation system and characterized for optical and physical properties. Reentry simulation tests were run using a radiant panel and also using a hypersonic plasma arc. The coatings produced had improved physical and optical properties as well as greater reuse capability over the GE version of the JSC-0042 coating.

Salt-Driven Deposition of Thermoresponsive Polymer-Coated Metal Nanoparticles on Solid Substrates.

PubMed

Zhang, Zhiyue; Maji, Samarendra; da Fonseca Antunes, André B; De Rycke, Riet; Hoogenboom, Richard; De Geest, Bruno G

2016-06-13

Here we report on a simple, generally applicable method for depositing metal nanoparticles on a wide variety of solid surfaces under all aqueous conditions. Noble-metal nanoparticles obtained by citrate reduction followed by coating with thermoresponsive polymers spontaneously form a monolayer-like structure on a wide variety of substrates in presence of sodium chloride whereas this phenomenon does not occur in salt-free medium. Interestingly, this phenomenon occurs below the cloud point temperature of the polymers and we hypothesize that salt ion-induced screening of electrostatic charges on the nanoparticle surface entropically favors hydrophobic association between the polymer-coated nanoparticles and a hydrophobic substrate. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Catalytic property of fiber media supported palladium containing alloy nanoparticles and electrospun ceramic fibers biodurability study

NASA Astrophysics Data System (ADS)

Shin, Hyeon Ung

The nanoscale of the supporting fibers may provide enhancements such as restricting the migration of metal catalyst particles. In this work, palladium nanoparticle doped alumina fibers were electrospun into template submicron fibers. These fibers were calcined at temperatures between 650°C and 1150°C to vary the crystal structures of the calcined fibers with the Pd particle size. Higher calcination temperatures led to higher reaction temperatures from 250 to about 450°C for total conversion, indicating the effective reactivity of the fiber-supported catalysts decreased with increase in calcination temperature. Pd-Au alloy nanoparticle doped titania fibers were also fabricated using an electrospinning method and assembled into a fibrous porous medium structure by a vacuum molding process. In reactor tests, the fiber media with Pd-Au alloy nanoparticle catalyst had greater reactivity in conversion of NO and CO gases than that of fiber media with Pd monometallic catalyst alone, attributed to a lower activation energy of the Pd-Au catalyst particles. In carbon monoxide oxidation reaction tests, the results showed that the performance was optimal for a catalyst of composition Pd2Au1 molar ratio that was active at 125°C, which had higher dispersion of active components and better catalytic performance compared to monometallic particle Au/TiO 2 and Pd/TiO2 fiber media. Moreover, the improved reaction activity of Pd2Au1/TiO2 fiber medium was attributed to a decreased in the activation energy. Further experiments were conducted using the electrospun ceramic fibers biodurability study. The properties of nano-sized fiber structures have attracted the attention of recent research on ceramic nanostructures as nonwoven media for applications in hazardous chemical and high temperature environments. However, health and safety concerns of micro and nano scale ceramic materials have not been fully investigated. Little is known about the physicochemical effects of the properties

Effects of ZnO nanoparticle-coated packaging film on pork meat quality during cold storage.

PubMed

Suo, Biao; Li, Huarong; Wang, Yuexia; Li, Zhen; Pan, Zhili; Ai, Zhilu

2017-05-01

There has been limited research on the use of ZnO nanoparticle-coated film for the quality preservation of pork meat under low temperature. In the present study, ZnO nanoparticles were mixed with sodium carboxymethyl cellulose (CMC-Na) to form a nanocomposite film, to investigate the effect of ZnO nanoparticle-coated film on pork meat quality and the growth of bacteria during storage under low temperature. When ZnO nanoparticle-coated film was used as the packaging material for pork meat for 14 days of cold storage at 4 °C, the results demonstrated a significant effect on restricting the increases in total volatile basic nitrogen and pH levels, limiting the decreases of lightness (increased L* value) and redness (increased a* value), and maintaining the water-holding capacity compared to the control pork samples (P < 0.05). The present study also discovered that the ZnO nanoparticle-coated film restrained the increase in total plate count (TPC). When Staphylococcus aureus was used as the representative strain, scanning electron microscopy revealed that ZnO nanoparticles increased the occurrence of cell membrane rupture under cold conditions. ZnO nanoparticle-coated film helps retain the quality of pork meat during cold storage by increasing the occurrence of microorganism injury. © 2016 Society of Chemical Industry. © 2016 Society of Chemical Industry.

Coatings Based on Nanodispersed Oxide Materials Produced by the Method of Pneumatic Spraying

NASA Astrophysics Data System (ADS)

Potekaev, A. I.; Lysak, I. A.; Malinovskaya, T. D.; Lysak, G. V.

2018-03-01

New approaches are proposed, relying on which the coatings from nanodispersed oxide materials are formed on polypropylene fibers. It is shown that in the course of the viscous fluid - solid state transition of the polymer its nanoparticles are stabilized on the surface of the formed fibers.

The role of nano-particles in the field of thermal spray coating technology

NASA Astrophysics Data System (ADS)

Siegmann, Stephan; Leparoux, Marc; Rohr, Lukas

2005-06-01

Nano-particles play not only a key role in recent research fields, but also in the public discussions about health and safety in nanotechnology. Nevertheless, the worldwide activities in nano-particles research increased dramatically during the last 5 to 10 years. There are different potential routes for the future production of nano-particles at large scale. The main directions envisaged are mechanical milling, wet chemical reactions or gas phase processes. Each of the processes has its specific advantages and limitations. Mechanical milling and wet chemical reactions are typically time intensive and batch processes, whereas gas phase productions by flames or plasma can be carried out continuously. Materials of interest are mainly oxide ceramics, carbides, nitrides, and pure metals. Nano-ceramics are interesting candidates for coating technologies due to expected higher coating toughness, better thermal shock and wear resistance. Especially embedded nano-carbides and-nitrides offer homogenously distributed hard phases, which enhance coatings hardness. Thermal spraying, a nearly 100 years old and world wide established coating technology, gets new possibilities thanks to optimized, nano-sized and/or nano-structured powders. Latest coating system developments like high velocity flame spraying (HVOF), cold gas deposition or liquid suspension spraying in combination with new powder qualities may open new applications and markets. This article gives an overview on the latest activities in nano-particle research and production in special relation to thermal spray coating technology.

Surface Coating of Plastic Parts for Business Machines (Industrial Surface Coating): New Source Performance Standards (NSPS)

EPA Pesticide Factsheets

Learn more about the new source performance standards (NSPS) for surface coating of plastic parts for business machines by reading the rule summary and history and finding the code of federal regulations as well as related rules.

The honey insertion cladding to improve the sensitivity of temperature polymer optical fiber sensor

NASA Astrophysics Data System (ADS)

Arwani, M.; Kuswanto, H.

2018-04-01

The sensitivity of temperature polymer optical fiber (POF) sensor has been studied. Part of cladding (9 cm) was substituted with honey. Polymer cladding was stripped mechanically and the honey inserted into the tube. Plastic gel closed the two end sides of the tubes. The optical power output was detected by Optical Power Meter (OPM). Honey cladding and temperature changing effect to the internal reflection and optical fiber output intensity. Highest output intensity changing at 20°C was shown by optical fiber coated by longan honey as cladding. The range of 10-50° C, as the rise of surroundings temperature, the attenuation was getting smaller. Best sensitivity was fiber with sensing part coated by Longan honey. Best linearity was sensing fiber with sensing part coated by Pracimantoro honey.

Optical fiber characteristics and standards; Proceedings of the Meeting, Cannes, France, November 25-27, 1985

NASA Technical Reports Server (NTRS)

Bouillie, Remy (Editor)

1986-01-01

Papers are presented on outside vapor deposition, the plasma activated CVD process for large scale production of telecommunication fibers, axial lateral plasma deposition technology from plastic clad silica, coatings for optical fibers, primary coating characterization, and radiation-induced time dependent attenuation in a fiber. Topics discussed include fibers with high tensile strength, the characteristics and specifications of airborne fiber optic components, the baseband frequency response of multimode fibers, and fibers for local and broadband networks. Consideration is given to industrial measurements for single mode and multimode fibers, the characterization of source power distribution in a multimode fiber by a splice offset technique, the measurement of chromatic dispersion in a single mode optical, and the effect of temperature on the refracted near-field optical fiber profiling technique.

PLA coated paper containing active inorganic nanoparticles: Material characterization and fate of nanoparticles in the paper recycling process.

PubMed

Zhang, Hai; Bussini, Daniele; Hortal, Mercedes; Elegir, Graziano; Mendes, Joana; Jordá Beneyto, Maria

2016-06-01

For paper and paperboard packaging, recyclability plays an important role in conserving the resources and reducing the environmental impacts. Therefore, when it comes to the nano-enabled paper packaging material, the recyclability issue should be properly addressed. This study represents our first report on the fate of nanomaterials in paper recycling process. The packaging material of concern is a PLA (Polylactic Acid) coated paper incorporating zinc oxide nanoparticles in the coating layer. The material was characterised and assessed in a lab-scale paper recycling line. The recyclability test was based on a method adapted from ATICELCA MC501-13, which enabled to recover over 99% of the solids material. The mass balance result indicates that 86-91% zinc oxide nanoparticles ended up in the rejected material stream, mostly embedded within the polymer coating; whereas 7-16% nanoparticles ended up in the accepted material stream. Besides, the tensile strength of the recycled handsheets suggests that the nano-enabled coating had no negative impacts on the recovered fibre quality. Copyright © 2016 Elsevier Ltd. All rights reserved.

Electrochemical analysis of gold-coated magnetic nanoparticles for detecting immunological interaction

NASA Astrophysics Data System (ADS)

Pham, Thao Thi-Hien; Sim, Sang Jun

2010-01-01

An electrochemical impedance immunosensor was developed for detecting the immunological interaction between human immunoglobulin (IgG) and protein A from Staphylococcus aureus based on the immobilization of human IgG on the surface of modified gold-coated magnetic nanoparticles. The nanoparticles with an Au shell and Fe oxide cores were functionalized by a self-assembled monolayer of 11-mercaptoundecanoic acid. The electrochemical analysis was conducted on the modified magnetic carbon paste electrodes with the nanoparticles. The magnetic nanoparticles were attached to the surface of the magnetic carbon paste electrodes via magnetic force. The cyclic voltammetry technique and electrochemical impedance spectroscopy measurements of the magnetic carbon paste electrodes coated with magnetic nanoparticles-human IgG complex showed changes in its alternating current (AC) response both after the modification of the surface of the electrode and the addition of protein A. The immunological interaction between human IgG on the surface of the modified magnetic carbon paste electrodes and protein A in the solution could be successfully monitored.

Water-repellent coatings prepared by modification of ZnO nanoparticles

NASA Astrophysics Data System (ADS)

Chakradhar, R. P. S.; Dinesh Kumar, V.

Superhydrophobic coatings with a static water contact angle (WCA) > 150° were prepared by modifying ZnO nanoparticles with stearic acid (ZnO@SA). ZnO nanoparticles of size ˜14 nm were prepared by solution combustion method. X-ray diffraction (XRD) studies reveal that as prepared ZnO has hexagonal wurtzite structure whereas the modified coatings convert to zinc stearate. Field emission scanning electron micrographs (FE-SEM) show the dual morphology of the coatings exhibiting both particles and flakes. The flakes are highly fluffy in nature with voids and nanopores. Fourier transformed infrared (FTIR) spectrum shows the stearate ion co-ordinates with Zn2+ in the bidentate form. The surface properties such as surface free energy (γp) and work of adhesion (W) of the unmodified and modified ZnO coatings have been evaluated. The electron paramagnetic resonance (EPR) spectroscopy reveals that surface defects play a major role in the wetting behavior.

Fast detection of humidity with a subwavelength-diameter fiber taper coated with gelatin film.

PubMed

Zhang, Lei; Gu, Fuxing; Lou, Jingyi; Yin, Xuefeng; Tong, Limin

2008-08-18

A subwavelength-diameter tapered optical fiber coated with gelatin layer for fast relative humidity (RH) sensing is reported. The sensing element is composed of a 680-nm-diameter fiber taper coated with a 80-nm-thickness 8-mm-length gelatin layer, and is operated at a wavelength of 1550 nm. When exposed to moisture, the change in refractive index of the gelatin layer changes the mode field of the guided mode of the coated fiber, and converts a portion of power from guided mode to radiation mode, resulting in RH-dependent loss for optical sensing. The sensor is operated within a wide humidity range (9-94% RH) with high sensitivity and good reversibility. Measured response time is about 70 ms, which is one or two orders of magnitude faster than other types of RH sensors relying on conventional optical fibers or films.

Respiration rate detection based on intensity modulation using plastic optical fiber

NASA Astrophysics Data System (ADS)

Anwar, Zawawi Mohd; Ziran Nurul Sufia, Nor; Hadi, Manap

2017-11-01

This paper presents the implementation of respiration rate measurement via a simple intensity-based optical fiber sensor using optical fiber technology. The breathing rate is measured based on the light intensity variation due to the longitudinal gap changes between two separated fibers. In order to monitor the breathing rate continuously, the output from the photodetector conditioning circuit is connected to a low-cost Arduino kit. At the sensing point, two optical fiber cables are positioned in series with a small gap and fitted inside a transparent plastic tube. To ensure smooth movement of the fiber during inhale and exhale processes as well as to maintain the gap of the fiber during idle condition, the fiber is attached firmly to a stretchable bandage. This study shows that this simple fiber arrangement can be applied to detect respiration activity which might be critical for patient monitoring.

Strength Analysis of Glass-Fiber-Reinforced Plastic during Buckling,

DTIC Science & Technology

An algorithm is developed for calculating and analyzing the stress tensor by the experimental function of deflections during the buckling of glass ... fiber -reinforced plastic shells loaded with a hydrostatic load. Malmeyster’s theory of strength is used to qualitatively establish the possible points of shell failure. (Author-PL)

Modeling of nanoparticle coatings for medical applications

NASA Astrophysics Data System (ADS)

Haume, Kaspar; Mason, Nigel J.; Solov'yov, Andrey V.

2016-09-01

Gold nanoparticles (AuNPs) have been shown to possess properties beneficial for the treatment of cancerous tumors by acting as radiosensitizers for both photon and ion radiation. Blood circulation time is usually increased by coating the AuNPs with poly(ethylene glycol) (PEG) ligands. The effectiveness of the PEG coating, however, depends on both the ligand surface density and length of the PEG molecules, making it important to understand the structure of the coating. In this paper the thickness, ligand surface density, and density of the PEG coating is studied with classical molecular dynamics using the software package MBN Explorer. AuNPs consisting of 135 atoms (approximately 1.4 nm diameter) in a water medium have been studied with the number of PEG ligands varying between 32 and 60. We find that the thickness of the coating is only weakly dependent on the surface ligand density and that the degree of water penetration is increased when there is a smaller number of attached ligands.

Carbon-coated nanoparticle superlattices for energy applications

NASA Astrophysics Data System (ADS)

Li, Jun; Yiliguma, Affa; Wang, Yifei; Zheng, Gengfeng

2016-07-01

Nanoparticle (NP) superlattices represent a unique material architecture for energy conversion and storage. Recent reports on carbon-coated NP superlattices have shown exciting electrochemical properties attributed to their rationally designed compositions and structures, fast electron transport, short diffusion length, and abundant reactive sites via enhanced coupling between close-packed NPs, which are distinctive from their isolated or disordered NP or bulk counterparts. In this minireview, we summarize the recent developments of highly-ordered and interconnected carbon-coated NP superlattices featuring high surface area, tailorable and uniform doping, high conductivity, and structure stability. We then introduce the precisely-engineered NP superlattices by tuning/studying specific aspects, including intermetallic structures, long-range ordering control, and carbon coating methods. In addition, these carbon-coated NP superlattices exhibit promising characteristics in energy-oriented applications, in particular, in the fields of lithium-ion batteries, fuel cells, and electrocatalysis. Finally, the challenges and perspectives are discussed to further explore the carbon-coated NP superlattices for optimized electrochemical performances.

Tailoring Interfacial Properties by Controlling Carbon Nanotube Coating Thickness on Glass Fibers Using Electrophoretic Deposition.

PubMed

Tamrakar, Sandeep; An, Qi; Thostenson, Erik T; Rider, Andrew N; Haque, Bazle Z Gama; Gillespie, John W

2016-01-20

The electrophoretic deposition (EPD) method was used to deposit polyethylenimine (PEI) functionalized multiwall carbon nanotube (CNT) films onto the surface of individual S-2 glass fibers. By varying the processing parameters of EPD following Hamaker's equation, the thickness of the CNT film was controlled over a wide range from 200 nm to 2 μm. The films exhibited low electrical resistance, providing evidence of coating uniformity and consolidation. The effect of the CNT coating on fiber matrix interfacial properties was investigated through microdroplet experiments. Changes in interfacial properties due to application of CNT coatings onto the fiber surface with and without a CNT-modified matrix were studied. A glass fiber with a 2 μm thick CNT coating and the unmodified epoxy matrix showed the highest increase (58%) in interfacial shear strength (IFSS) compared to the baseline. The increase in the IFSS was proportional to CNT film thickness. Failure analysis of the microdroplet specimens indicated higher IFSS was related to fracture morphologies with higher levels of surface roughness. EPD enables the thickness of the CNT coating to be adjusted, facilitating control of fiber/matrix interfacial resistivity. The electrical sensitivity provides the opportunity to fabricate a new class of sizing with tailored interfacial properties and the ability to detect damage initiation.

Strength of anisotropic wood and synthetic materials. [plywood, laminated wood plastics, glass fiber reinforced plastics, polymeric film, and natural wood

NASA Technical Reports Server (NTRS)

Ashkenazi, Y. K.

1981-01-01

The possibility of using general formulas for determining the strength of different anisotropic materials is considered, and theoretical formulas are applied and confirmed by results of tests on various nonmetallic materials. Data are cited on the strength of wood, plywood, laminated wood plastics, fiber glass-reinforced plastics and directed polymer films.

About the role of phase matching between a coated microsphere and a tapered fiber: experimental study.

PubMed

Ristić, Davor; Rasoloniaina, Alphonse; Chiappini, Andrea; Féron, Patrice; Pelli, Stefano; Conti, Gualtiero Nunzi; Ivanda, Mile; Righini, Giancarlo C; Cibiel, Gilles; Ferrari, Maurizio

2013-09-09

Coatings of spherical optical microresonators are widely employed for different applications. Here the effect of the thickness of a homogeneous coating layer on the coupling of light from a tapered fiber to a coated microsphere has been studied. Spherical silica microresonators were coated using a 70SiO(2)- 30HfO(2) glass doped with 0.3 mol% Er(3+) ions. The coupling of a 1480 nm pump laser inside the sphere has been assessed using a tapered optical fiber and observing the 1530-1580 nm Er(3+) emission outcoupled to the same tapered fiber. The measurements were done for different coating thicknesses and compared with theoretical calculations to understand the relationship of the detected signal with the whispering gallery mode electric field profiles.

Effect of metal coating in all-fiber acousto-optic tunable filter using torsional wave.

PubMed

Song, Du-Ri; Jun, Chang Su; Do Lim, Sun; Kim, Byoung Yoon

2014-12-15

Torsional mode acousto-optic tunable filter (AOTF) is demonstrated using a metal-coated birefringent optical fiber for an improved robustness. The changes in acoustic and optical properties of a metal-coated birefringent optical fiber induced by the thin metal coating were analyzed experimentally and theoretically. The filter wavelength shift is successfully explained as a result of combined effect of acoustic wavelength change and optical birefringence change. We also demonstrated a small form-factor configuration by coiling the fiber with 6 cm diameter without performance degradation. The center wavelength of the filter can be tuned >35 nm by changing the applied frequency, and the coupling efficiency is higher than 92% with <5 nm 3-dB bandwidth.

Glucose-Coated Gold Nanoparticles Transfer across Human Brain Endothelium and Enter Astrocytes In Vitro

PubMed Central

Gromnicova, Radka; Davies, Heather A.; Sreekanthreddy, Peddagangannagari; Romero, Ignacio A.; Lund, Torben; Roitt, Ivan M.; Phillips, James B.; Male, David K.

2013-01-01

The blood-brain barrier prevents the entry of many therapeutic agents into the brain. Various nanocarriers have been developed to help agents to cross this barrier, but they all have limitations, with regard to tissue-selectivity and their ability to cross the endothelium. This study investigated the potential for 4 nm coated gold nanoparticles to act as selective carriers across human brain endothelium and subsequently to enter astrocytes. The transfer rate of glucose-coated gold nanoparticles across primary human brain endothelium was at least three times faster than across non-brain endothelia. Movement of these nanoparticles occurred across the apical and basal plasma membranes via the cytosol with relatively little vesicular or paracellular migration; antibiotics that interfere with vesicular transport did not block migration. The transfer rate was also dependent on the surface coating of the nanoparticle and incubation temperature. Using a novel 3-dimensional co-culture system, which includes primary human astrocytes and a brain endothelial cell line hCMEC/D3, we demonstrated that the glucose-coated nanoparticles traverse the endothelium, move through the extracellular matrix and localize in astrocytes. The movement of the nanoparticles through the matrix was >10 µm/hour and they appeared in the nuclei of the astrocytes in considerable numbers. These nanoparticles have the correct properties for efficient and selective carriers of therapeutic agents across the blood-brain barrier. PMID:24339894

Experimental demonstration of all-optical weak magnetic field detection using beam-deflection of single-mode fiber coated with cobalt-doped nickel ferrite nanoparticles.

PubMed

Pradhan, Somarpita; Chaudhuri, Partha Roy

2015-07-10

We experimentally demonstrate single-mode optical-fiber-beam-deflection configuration for weak magnetic-field-detection using an optimized (low coercive-field) composition of cobalt-doped nickel ferrite nanoparticles. Devising a fiber-double-slit type experiment, we measure the surrounding magnetic field through precisely measuring interference-fringe yielding a minimum detectable field ∼100  mT and we procure magnetization data of the sample that fairly predicts SQUID measurement. To improve sensitivity, we incorporate etched single-mode fiber in double-slit arrangement and recorded a minimum detectable field, ∼30  mT. To further improve, we redefine the experiment as modulating fiber-to-fiber light-transmission and demonstrate the minimum field as 2.0 mT. The device will be uniquely suited for electrical or otherwise hazardous environments.

Electrodeposited polyaniline as a fiber coating for solid-phase microextraction of organochlorine pesticides from water.

PubMed

Li, Xiang; Zhong, Ming; Chen, Jianmin

2008-08-01

The study on the performance of polyaniline as a fiber coating for solid-phase microextraction (SPME) purposes has been reported. Polyaniline coatings were directly electrodeposited on the surface of a stainless steel wire and applied for the extraction of some organochlorine pesticides (OCPs) from water samples. Analyses were performed using GC-electron capture detection (GC-ECD). The results obtained show that polyaniline fiber coating is suitable for the successful extraction of organochlorine compounds. This behavior is most probably due to the porous surface structure of polyaniline film, which provides large surface areas and allowed for high extraction efficiency. Experimental parameters such as adsorption and desorption conditions were studied and optimized. The optimized method has an acceptable linearity, with a concentration range of 1-5000 ng/L. Single fiber repeatability and fiber-to-fiber reproducibility were less than 12 and 17%, respectively. High environmental resistance and lower cost are among the advantages of polyaniline fibers over commercially available SPME fibers. The developed method was applied to the analysis of real water samples from Yangtse River and Tianmu Lake.

Synthesis and characterization of cationic lipid coated magnetic nanoparticles using multiple emulsions as microreactors

NASA Astrophysics Data System (ADS)

Akbaba, Hasan; Karagöz, Uğur; Selamet, Yusuf; Kantarcı, A. Gülten

2017-03-01

The aim of this study was to develop a novel iron oxide nanoparticle synthesis method with in-situ surface coating. For this purpose multiple emulsions were used as microreactors for the first time and magnetic iron oxide particles synthesized in the core of cationic solid lipid nanoparticles. DLS, SEM, TEM, VSM, Raman Spectrometer, XRD, and XPS techniques were performed for characterization of the magnetic nanoparticles. Obtained magnetic nanoparticles are superparamagnetic and no additional process was needed for surface adjustments. They are positively charged as a result of cationic lipid coating and has appropriate particle size (<30 nm) for drug or nucleic acid delivery. Structure analysis showed that magnetic core material is in the form of magnetite. Saturation magnetization value was measured as 15-17 emu g-1 for lipid coated magnetic nanoparticles obtained by multiple emulsion method which is reasonably sufficient for magnetic targeting.

Theoretical Analysis and Experimental Study on the Coating Removal from Passenger-Vehicle Plastics for Recycling by Using Water Jet Technology

NASA Astrophysics Data System (ADS)

Zhang, Hongshen; Chen, Ming

2015-11-01

The recovery and utilization of automotive plastics are a global concern because of the increasing number of end-of-life vehicles. In-depth studies on technologies for the removal of coatings from automotive plastics can contribute to the high value-added levels of the recycling and utilization of automotive plastic. The liquid waste generated by removing chemical paint by using traditional methods is difficult to handle and readily produces secondary pollution. Therefore, new, clean, and highly efficient techniques of paint removal must be developed. In this article, a method of coating removal from passenger-vehicle plastics was generated based on high-pressure water jet technology to facilitate the recycling of these plastics. The established technology was theoretically analyzed, numerically simulated, and experimentally studied. The high-pressure water jet equipment for the removal of automotive-plastic coatings was constructed through research and testing, and the detailed experiments on coating removal rate were performed by using this equipment. The results showed that high-pressure water jet technology can effectively remove coatings on the surfaces of passenger-vehicle plastics. The research also revealed that the coating removal rate increased as jet pressure ( P) increased and then decreased when jet moving speed ( Vn) increased. The rate decreased as the distance from nozzle to work piece ( S nw ) and the nozzle angle ( Φ) increased. The mathematical model for the rate of removal of coatings from bumper surfaces by water jet was derived based on the experiment data and can effectively predict coating removal rate under different operating conditions.

Plastic fiber optics for micro-imaging of fluorescence signals in living cells

NASA Astrophysics Data System (ADS)

Sakurai, Takashi; Natsume, Mitsuo; Koida, Kowa

2015-03-01

The fiber-coupled microscope (FCM) enables in vivo imaging at deep sites in the tissues or organs that other optical techniques are unable to reach. To develop FCM-based intravital imaging, we employed a plastic optical fiber (POF) bundle that included more than 10,000-units of polystyrene core and polymethyl methacrylate cladding. Each POF had a diameter of less than 5 μm the tip of the bundle was less than 0.5 mm wide, and the flexible wire had a length of 1,000 mm. The optical performance of the plastic FCM was sufficient for detection of significant signal changes in an acinus of rat pancreas labeled with a calcium ion-sensitive fluorescent dye. In the future, the potential power of plastic FCM is expected to increase, enabling analysis of structure and organization of specific functions in live cells within vulnerable organs.

Design of water-repellant coating using dual scale size of hybrid silica nanoparticles on polymer surface

NASA Astrophysics Data System (ADS)

Conti, J.; De Coninck, J.; Ghazzal, M. N.

2018-04-01

The dual-scale size of the silica nanoparticles is commonly aimed at producing dual-scale roughness, also called hierarchical roughness (Lotus effect). In this study, we describe a method to build a stable water-repellant coating with controlled roughness. Hybrid silica nanoparticles are self-assembled over a polymeric surface by alternating consecutive layers. Each one uses homogenously distributed silica nanoparticles of a particular size. The effect of the nanoparticle size of the first layer on the final roughness of the coating is studied. The first layer enables to adjust the distance between the silica nanoparticles of the upper layer, leading to a tuneable and controlled final roughness. An optimal size nanoparticle has been found for higher water-repellency. Furthermore, the stability of the coating on polymeric surface (Polycarbonate substrate) is ensured by photopolymerization of hybridized silica nanoparticles using Vinyl functional groups.

Preparation and characterization of boron nitride coatings on carbon fibers from borazine by chemical vapor deposition

NASA Astrophysics Data System (ADS)

Li, Jun-Sheng; Zhang, Chang-Rui; Li, Bin

2011-06-01

Boron nitride (BN) coatings were deposited on carbon fibers by chemical vapor deposition (CVD) using borazine as single source precursor. The deposited coatings were characterized by scanning electron microscopy (SEM), Auger electron spectroscopy (AES), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR) and Raman spectroscopy. The effect of temperatures on growth kinetics, morphology, composition and structure of the coatings was investigated. In the low temperature range of 900 °C-1000 °C, the growth rate increased with increasing temperature complying with Arrhenius law, and an apparent active energy of 72 kJ/mol was calculated. The coating surface was smooth and compact, and the coatings uniformly deposited on individual fibers of carbon fiber bundles. The growth was controlled by surface reaction. At 1000 °C, the deposition rate reached a maximum (2.5 μm/h). At the same time, the limiting step of the growth translated to be mass-transportation. Above 1100 °C, the growth rate decreased drastically due to the occurrence of gas-phase nucleation. Moreover, the coating surface became loose and rough. Composition and structure examinations revealed that stoichiometric BN coatings with turbostratic structure were obtained below 1000 °C, while hexagonal BN coatings were deposited above 1100 °C. A penetration of carbon element from the fibers to the coatings was observed.

Elasto-plastic analysis of interface layers for fiber reinforced metal matrix composites

NASA Technical Reports Server (NTRS)

Doghri, I.; Leckie, F. A.

1991-01-01

The mismatch in coefficients of thermal expansion (CTE) of fiber and matrix in metal matrix composites reinforced with ceramic fibers induces high thermal stresses in the matrix. Elasto-plastic analyses - with different degrees of simplification and modelization - show that an interface layer with a sufficiently high CTE can reduce the tensile hoop stress in the matrix substantially.

Erosion Characteristics of Nanoparticle-Reinforced Polyurethane Coatings on Stainless Steel Substrate

NASA Astrophysics Data System (ADS)

Syamsundar, C.; Chatterjee, Dhiman; Kamaraj, M.; Maiti, A. K.

2015-04-01

Hydropower generation from the Himalayan rivers in India faces challenge in the form of silt-laden water which can erode the turbine blades and reduce turbine life. To address this issue, polyurethane coatings reinforced with boron carbide (B4C) or silicon carbide (SiC) nanoparticles on 16Cr-5Ni martensitic stainless steel substrate were used in the present investigation to improve erosion wear resistance in silt erosion conditions. Slurry erosive wear tests were carried out based on ASTM G-73 protocol at various test conditions of impact velocity, impingement angle, and erodent particle size as well as slurry concentrations as determined by the implementation of Taguchi design of experiments. Analysis of variance studies of erosion rate indicated that nanoparticle content in PU material is the single most important parameter, and interaction of impact velocity and impingement angle was also proved to be significant. The coatings with B4C nanoparticles had higher wear resistances than those with SiC nanoparticles due to higher hardness of the former. An interesting finding from the results is that there is an optimum amount of nanoparticles at which mass removal is the minimum. This observation has been explained in terms of surface characteristics of coatings as brought out by a combination of measurements including SEM images as well as roughness measurement.

Structural and morphological characterization of anatase TiO 2 coating on χ-Alumina scale fiber fabricated by sol-gel dip-coating method

NASA Astrophysics Data System (ADS)

Nguyen, Hue Thi; Miao, Lei; Tanemura, Sakae; Tanemura, Masaki; Toh, Shoichi; Kaneko, Kenji; Kawasaki, Masahiro

2004-10-01

Anatase TiO 2 coatings 0.4 μm thick have been successfully fabricated by sol-gel dip-coating process on χ-Al 2O 3 fibers 100 μm by 10 cm long with a surface fish-scale. This was achieved by adjustment of the sol-gel parameters such as molar ratio of the precursors in TiO 2-sols, dip-coating time, drying duration in air, heating processes and number of cyclical repetitions of the process. Two samples were prepared using two sols containing different molar ratios of precursors. XRD, TEM, EDS and SEM characterization confirmed: (1) the similarity of the growth of anatase-TiO 2 from two sols under the optimal sol-gel parameters, (2) that the coatings are composed of aggregated crystallites of 10-25 nm in diameter, (3) the good compositional uniformity of Ti in the fabricated anatase-TiO 2 crystallites, (4) a surface covering ratio of anatase-TiO 2 around the fiber of at least 90%, and (5) that there is a good adherence of the fabricated anatase-TiO 2 layer on alumina fiber as evidenced by the lack of cracking and peeling off traces around the boundary between the coating and the fiber.

Graphite coated PVA fibers as the reinforcement for cementitious composites

NASA Astrophysics Data System (ADS)

Zhang, Yunhua; Zhang, Zhipeng; Liu, Zhichao

2018-02-01

A new preconditioning method was developed to PVA fibers as the reinforcement in cement-based materials. Virgin PVA fibers exhibits limited adhesion to graphite powders due to the presence of oil spots on the surface. Mixing PVA fibers with a moderately concentrated KMnO4-H2SO4 solution can efficiently remove the oil spots by oxidation without creating extra precipitate (MnO2) associated with the reduction reaction. This enhances the coating of graphite powders onto fiber surface and improves the mechanical properties of PVA fiber reinforced concrete (PVA-FRC). Graphite powders yields better fiber distribution in the matrix and reduces the fiber-matrix bonding, which is beneficial in uniformly distributing the stress among embedded fibers and creating steady generation and propagation of tight microcracks. This is evidenced by the significantly enhanced strain hardening behavior and improved flexural strength and toughness.

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

PubMed

Liu, Junpeng; Janjua, Zaid A; Roe, Martin; Xu, Fang; Turnbull, Barbara; Choi, Kwing-So; Hou, Xianghui

2016-12-02

A super-hydrophobic surface has been obtained from nanocomposite materials based on silica nanoparticles and self-assembled monolayers of 1 H ,1 H ,2 H ,2 H -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.

Synthesis of amino-rich silica-coated magnetic nanoparticles for the efficient capture of DNA for PCR.

PubMed

Bai, Yalong; Cui, Yan; Paoli, George C; Shi, Chunlei; Wang, Dapeng; Zhou, Min; Zhang, Lida; Shi, Xianming

2016-09-01

Magnetic separation has great advantages over traditional bio-separation methods and has become popular in the development of methods for the detection of bacterial pathogens, viruses, and transgenic crops. Functionalization of magnetic nanoparticles is a key factor for efficient capture of the target analytes. In this paper, we report the synthesis of amino-rich silica-coated magnetic nanoparticles using a one-pot method. This type of magnetic nanoparticle has a rough surface and a higher density of amino groups than the nanoparticles prepared by a post-modification method. Furthermore, the results of hydrochloric acid treatment indicated that the magnetic nanoparticles were stably coated. The developed amino-rich silica-coated magnetic nanoparticles were used to directly adsorb DNA. After magnetic separation and blocking, the magnetic nanoparticles and DNA complexes were used directly for the polymerase chain reaction (PCR), without onerous and time-consuming purification and elution steps. The results of real-time quantitative PCR showed that the nanoparticles with higher amino group density resulted in improved DNA capture efficiency. The results suggest that amino-rich silica-coated magnetic nanoparticles are of great potential for efficient bio-separation of DNA prior to detection by PCR. Copyright © 2016. Published by Elsevier B.V.

The effect of carboxylic acids on the oxidation of coated iron oxide nanoparticles

NASA Astrophysics Data System (ADS)

Lengyel, Attila; Tolnai, Gyula; Klencsár, Zoltán; Garg, Vijayendra Kumar; de Oliveira, Aderbal Carlos; Herojit Singh, L.; Homonnay, Zoltán; Szalay, Roland; Németh, Péter; Szabolcs, Bálint; Ristic, Mira; Music, Svetozar; Kuzmann, Ernő

2018-05-01

57Fe Mössbauer spectroscopy, XRD, and TEM were used to investigate the effect of mandelic- and salicylic acid coatings on the iron oxide nanoparticles. These two carboxylic acids have similar molecules size and stoichiometry, but different structure and acidity. Significant differences were observed between the Mössbauer spectra of samples coated with mandelic acid and salicylic acid. These results indicate that the occurrence of iron microenvironments in the mandelic- and salicylic acid-coated iron oxide nanoparticles is different. The results can be interpreted in terms of the influence of the acidity of carboxylic acids on the formation, core/shell structure, and oxidation of coated iron oxide nanocomposites.

Fabrication of Fe–Co Magnetostrictive Fiber Reinforced Plastic Composites and Their Sensor Performance Evaluation

PubMed Central

Katabira, Kenichi; Yoshida, Yu; Masuda, Atsuji; Watanabe, Akihito; Narita, Fumio

2018-01-01

The inverse magnetostrictive effect is an effective property for energy harvesting; the material needs to have large magnetostriction and ease of mass production. Fe–Co alloys being magnetostrictive materials have favorable characteristics which are high strength, ductility, and excellent workability, allowing easy fabrication of Fe–Co alloy fibers. In this study, we fabricated magnetostrictive polymer composites, in which Fe–Co fibers were woven into polyester fabric, and discussed their sensor performance. Compression and bending tests were carried out to measure the magnetic flux density change, and the effects of magnetization, bias magnetic field, and the location of the fibers on the performance were discussed. It was shown that magnetic flux density change due to compression and bending is related to the magnetization of the Fe–Co fiber and the bias magnetic field. The magnetic flux density change of Fe–Co fiber reinforced plastics was larger than that of the plastics with Terfenol-D particles. PMID:29522455

Effects of Fiber Coatings on Tensile Properties of Hi-Nicalon SiC/RBSN Tow Composites

NASA Technical Reports Server (NTRS)

Bhatt, Ramakrishna T.; Hull, David R.

1997-01-01

Uncoated Hi-Nicalon silicon carbide (SiC) fiber tows and those coated with a single surface layer of pyrolytic boron nitride (PBN), double layers of PBN/Si-rich PBN, and boron nitride (BN)/SiC coatings deposited by chemical vapor deposition (CVD) method were infiltrated with silicon slurry and then exposed to N2, for 4 hr at 1200 and 1400 C. Room temperature ultimate tensile fracture loads and microstructural characterization of uncoated and CVD coated Hi-Nicalon SiC fiber reinforced reaction-bonded silicon nitride (RBSN) tow composites were measured to select suitable interface coating(s) stable under RBSN processing conditions. Results indicate that room temperature ultimate fracture loads of the uncoated Hi-Nicalon SiC/RBSN tow composites nitrided at both temperatures were significantly lower than those of the uncoated Hi-Nicalon tows without slurry infiltration. In contrast, all CVD coated Hi-Nicalon SiC/RBSN tow composites retained a greater fraction of the dry tow fracture load after nitridation at 1200 C, but degraded significantly after nitridation at 1400 C. Reaction between metal impurities (Fe and Ni) present in the attrition milled silicon powder and uncoated regions of SiC fibers appears to be the probable cause for fiber degradation.

Applications of thin carbon coatings and films in injection molding

NASA Astrophysics Data System (ADS)

Cabrera, Eusebio Duarte

In this research, the technical feasibility of two novel applications of thin carbon coatings is demonstrated. The first application consists of using thin carbon coatings on molds for molding ultra-thin plastic parts (<0.5 mm thickness) with lower pressures by promoting wall slip. The second application consists of a new approach to provide electromagnetic interference (EMI) shielding for plastic parts using in mold coated nanoparticle thin films or nanopapers to create a conductive top layer. During this research, the technical feasibility of a new approach was proven which provides injection molding of ultra-thin parts at lower pressures, without the need of fast heating/fast cooling or other expensive mold modification. An in-house developed procedure by other members of our group, was employed for coating the mold surface using chemical vapor deposition (CVD) resulting in a graphene coating with carbide bonding to the mold surface. The coating resulted in a significant decrease of surface friction and consequently easiness of flow when compared to their uncoated counterparts. Thermoplastic polymers and their composites are a very attractive alternative but are hindered by the non-conductive nature of polymers. There are two general approaches used to date to achieve EMI shielding for plastic products. One is to spray a conductive metal coating onto the plastic surface forming a layer that must maintain its shielding effectiveness (SE), and its adhesion to the plastic throughout the expected life of the product. However, metal coatings add undesirable weight and tend to corrode over time. Furthermore, scratching the coating may create shielding failure; therefore, a protective topcoat may be required. The other approach is to use polymer composites filled with conductive fillers such as carbon black (CB), carbon nanofiber (CNF), and carbon nanotube (CNT). While conductive fillers may increase the electrical conductivity of polymer composites, the loading of

Highly porous solid-phase microextraction fiber coating based on poly(ethylene glycol)-modified ormosils synthesized by sol-gel technology.

PubMed

da Costa Silva, Raquel Gomes; Augusto, Fabio

2005-04-22

The preparation and characteristics of solid-phase microextraction (SPME) fibers coated with Carbowax 20M ormosil (organically modified silica) are described here. Raw fused silica fibers were coated with Carbowax 20M-modified silica using sol-gel process. Scanning electron micrographs of fibers revealed a highly porous, sponge-like coating with an average thickness of (8 +/- 1) microm. The sol-gel Carbowax fibers were compared to commercial fibers coated with 100 microm polydimethylsiloxane (PDMS) and 65 microm Carbowax-divinylbenzene (DVB). Shorter equilibrium times were possible with the sol-gel Carbowax fiber: for headspace extraction of the test analytes, they ranged from less than 3 min for benzene to 15 min for o-xylene. Extraction efficiencies of the sol-gel Carbowax fiber were superior to those of conventional fibers: for o-xylene, the extracted masses were 230 and 540% of that obtained with 100 microm PDMS and 65 microm Carbowax-DVB fibers, respectively.

Light-triggered 5-fluorouracil release via UiO-66 coated optical fiber

NASA Astrophysics Data System (ADS)

Nazari, Marziyeh; Rubio-Martinez, Marta; Nazari, Fatemeh; Younis, Adel Ayad; Collins, Stephen F.; Duke, Mikel C.; Hill, Matthew R.

2017-07-01

UiO-66 thin film coated optical fiber end-face is fabricated and was utilized for 5-Fluorouracil (5-FU) anti-cancer medicine encapsulation and the drug was released by applying the appropriate light delivered via the optical fiber.

Preparation and Properties of Electrospun Poly (Vinyl Pyrrolidone)/Cellulose Nanocrystal/Silver Nanoparticle Composite Fibers

PubMed Central

Huang, Siwei; Zhou, Ling; Li, Mei-Chun; Wu, Qinglin; Kojima, Yoichi; Zhou, Dingguo

2016-01-01

Poly (vinyl pyrrolidone) (PVP)/cellulose nanocrystal (CNC)/silver nanoparticle composite fibers were prepared via electrospinning using N,N′-dimethylformamide (DMF) as a solvent. Rheology, morphology, thermal properties, mechanical properties, and antimicrobial activity of nanocomposites were characterized as a function of material composition. The PVP/CNC/Ag electrospun suspensions exhibited higher conductivity and better rheological properties compared with those of the pure PVP solution. The average diameter of the PVP electrospun fibers decreased with the increase in the amount of CNCs and Ag nanoparticles. Thermal stability of electrospun composite fibers was decreased with the addition of CNCs. The CNCs help increase the composite tensile strength, while the elongation at break decreased. The composite fibers included Ag nanoparticles showed improved antimicrobial activity against both the Gram-negative bacterium Escherichia coli (E. coli) and the Gram-positive bacterium Staphylococcus aureus (S. aureus). The enhanced strength and antimicrobial performances of PVP/CNC/Ag electrospun composite fibers make the mat material an attractive candidate for application in the biomedical field. PMID:28773644

Effects of Temperature and X-rays on Plastic Scintillating Fiber and Infrared Optical Fiber.

PubMed

Lee, Bongsoo; Shin, Sang Hun; Jang, Kyoung Won; Yoo, Wook Jae

2015-05-11

In this study, we have studied the effects of temperature and X-ray energy variations on the light output signals from two different fiber-optic sensors, a fiber-optic dosimeter (FOD) based on a BCF-12 as a plastic scintillating fiber (PSF) and a fiber-optic thermometer (FOT) using a silver halide optical fiber as an infrared optical fiber (IR fiber). During X-ray beam irradiation, the scintillating light and IR signals were measured simultaneously using a dosimeter probe of the FOD and a thermometer probe of the FOT. The probes were placed in a beaker with water on the center of a hotplate, under variation of the tube potential of a digital radiography system or the temperature of the water in the beaker. From the experimental results, in the case of the PSF, the scintillator light output at the given tube potential decreased as the temperature increased in the temperature range from 25 to 60 °C. We demonstrated that commonly used BCF-12 has a significant temperature dependence of -0.263 ± 0.028%/°C in the clinical temperature range. Next, in the case of the IR fiber, the intensity of the IR signal was almost uniform at each temperature regardless of the tube potential range from 50 to 150 kVp. Therefore, we also demonstrated that the X-ray beam with an energy range used in diagnostic radiology does not affect the IR signals transmitted via a silver halide optical fiber.

In vivo two-photon imaging of climbing fibers plasticity after laser axotomy

NASA Astrophysics Data System (ADS)

Allegra Mascaro, A. L.; Cesare, P.; Sacconi, L.; Grasselli, G.; Mandolesi, G.; Maco, B.; Knott, G. W.; De Paola, V.; Strata, P.; Pavone, F. S.

2013-06-01

In the adult nervous system, different neuronal classes show different regenerative behavior. Although previous studies demonstrated that olivocerebellar fibers are capable of axonal regeneration in a suitable environment as a response to injury, we have hitherto no details about the real dynamics of fiber regeneration. We set up a model of singularly axotomized climbing fibers (CF) to investigate their reparative properties in the adult central nervous system (CNS) in vivo. Here we describe the approach followed to characterize the reactive plasticity after injury.

Synthesis of surface bound silver nanoparticles on cellulose fibers using lignin as multi-functional agent.

PubMed

Hu, Sixiao; Hsieh, You-Lo

2015-10-20

Lignin has proven to be highly effective "green" multi-functional binding, complexing and reducing agents for silver cations as well as capping agents for the synthesis of silver nanoparticles on ultra-fine cellulose fibrous membranes. Silver nanoparticles could be synthesized in 10min to be densely distributed and stably bound on the cellulose fiber surfaces at up to 2.9% in mass. Silver nanoparticle increased in sizes from 5 to 100nm and became more polydispersed in size distribution on larger fibers and with longer synthesis time. These cellulose fiber bound silver nanoparticles did not agglomerate under elevated temperatures and showed improved thermal stability. The presence of alkali lignin conferred moderate UV absorbing ability in both UV-B and UV-C regions whereas the bound silver nanoparticles exhibited excellent antibacterial activities toward Escherichia coli. Copyright © 2015 Elsevier Ltd. All rights reserved.

Characterization and Effects of Fiber Pull-Outs in Hole Quality of Carbon Fiber Reinforced Plastics Composite.

PubMed

Alizadeh Ashrafi, Sina; Miller, Peter W; Wandro, Kevin M; Kim, Dave

2016-10-13

Hole quality plays a crucial role in the production of close-tolerance holes utilized in aircraft assembly. Through drilling experiments of carbon fiber-reinforced plastic composites (CFRP), this study investigates the impact of varying drilling feed and speed conditions on fiber pull-out geometries and resulting hole quality parameters. For this study, hole quality parameters include hole size variance, hole roundness, and surface roughness. Fiber pull-out geometries are quantified by using scanning electron microscope (SEM) images of the mechanically-sectioned CFRP-machined holes, to measure pull-out length and depth. Fiber pull-out geometries and the hole quality parameter results are dependent on the drilling feed and spindle speed condition, which determines the forces and undeformed chip thickness during the process. Fiber pull-out geometries influence surface roughness parameters from a surface profilometer, while their effect on other hole quality parameters obtained from a coordinate measuring machine is minimal.

Compressibility of porous TiO2 nanoparticle coating on paperboard

PubMed Central

2013-01-01

Compressibility of liquid flame spray-deposited porous TiO2 nanoparticle coating was studied on paperboard samples using a traditional calendering technique in which the paperboard is compressed between a metal and polymer roll. Surface superhydrophobicity is lost due to a smoothening effect when the number of successive calendering cycles is increased. Field emission scanning electron microscope surface and cross‒sectional images support the atomic force microscope roughness analysis that shows a significant compressibility of the deposited TiO2 nanoparticle coating with decrease in the surface roughness and nanoscale porosity under external pressure. PACS 61.46.-w; 68.08.Bc; 81.07.-b PMID:24160373

Effects of Coating and Diametric Load on Fiber Bragg Gratings as Cryogenic Temperature Sensors

NASA Technical Reports Server (NTRS)

Wu, meng-Chou; Pater, Ruth H.; DeHaven, Stanton L.

2008-01-01

Cryogenic temperature sensing was demonstrated using pressurized fiber Bragg gratings (PFBGs) with polymer coating of various thicknesses. The PFBG was obtained by applying a small diametric load to a regular fiber Bragg grating (FBG). The Bragg wavelengths of FBGs and PFBG were measured at temperatures from 295 K to 4.2 K. The temperature sensitivities of the FBGs were increased by the polymer coating. A physical model was developed to relate the Bragg wavelength shifts to the thermal expansion coefficients, Young's moduli, and thicknesses of the coating polymers. When a diametric load of no more than 15 N was applied to a FBG, a pressure-induced transition occurred at 200 K during the cooling cycle. The pressure induced transition yielded PFBG temperature sensitivities three times greater than conventional FBGs for temperatures ranging from 80 to 200 K, and ten times greater than conventional fibers for temperatures below 80 K. PFBGs were found to produce an increased Bragg wavelength shift of 2.2 nm compared to conventional FBGs over the temperature range of 4.2 to 300 K. This effect was independent of coating thickness and attributed to the change of the fiber thermo-optic coefficient.

Conatumumab (AMG 655) coated nanoparticles for targeted pro-apoptotic drug delivery.

PubMed

Fay, Francois; McLaughlin, Kirsty M; Small, Donna M; Fennell, Dean A; Johnston, Patrick G; Longley, Daniel B; Scott, Christopher J

2011-11-01

Colloidal nanoparticle drug delivery systems have attracted much interest for their ability to enable effective formulation and delivery of therapeutic agents. The selective delivery of these nanoparticles to the disease site can be enhanced by coating the surface of the nanoparticles with targeting moieties, such as antibodies. In this current work, we demonstrate that antibodies on the surface of the particles can also elicit key biological effects. Specifically, we demonstrate the induction of apoptosis in colorectal HCT116 cancer cells using PLGA nanoparticles coated with Conatumumab (AMG 655) death receptor 5-specific antibodies (DR5-NP). We show that DR5-NP preferentially target DR5-expressing cells and present a sufficient density of antibody paratopes to induce apoptosis via DR5, unlike free AMG 655 or non-targeted control nanoparticles. We also demonstrate that DR5-targeted nanoparticles encapsulating the cytotoxic drug camptothecin are effectively targeted to the tumour cells, thereby producing enhanced cytotoxic effects through simultaneous drug delivery and apoptosis induction. These results demonstrate that antibodies on nanoparticulate surfaces can be exploited for dual modes of action to enhance the therapeutic utility of the modality. Copyright © 2011 Elsevier Ltd. All rights reserved.

Enteric-coated sustained-release nanoparticles by coaxial electrospray: preparation, characterization, and in vitro evaluation

NASA Astrophysics Data System (ADS)

Hao, Shilei; Wang, Bochu; Wang, Yazhou; Xu, Yingqian

2014-02-01

Enteric-coated formulations can delay the release of drugs until they have passed through the stomach. However, high concentration of drugs caused by rapidly released in the small intestine leads to the intestinal damage, and frequent administration would increase the probability of missing medication and reduce the patient compliance. To solve the above-mentioned problems, aspirin-loaded enteric-coated sustained-release nanoparticles with core-shell structure were prepared via one-step method using coaxial electrospray in this study. Eudragit L100-55 as pH-sensitive polymer and Eudragit RS as sustained-release polymer were used for the outer coating and inner core of the nanoparticles, respectively. The maximum loading capacity of nanoparticles was 23.66 % by changing the flow rate ratio of outer/inner solutions, and the entrapment efficiency was nearly 100 %. Nanoparticles with core-shell structure were observed via fluorescence microscope and transmission electron microscope. And pH-sensitive and sustained drug release profiles were observed in the media with different pH values (1.2 and 6.8). In addition, mild cytotoxicity in vitro was detected, and the nanoparticles could be taken up by Caco-2 cells within 1.0 h in cellular uptake study. These results indicate that prepared enteric-coated sustained-release nanoparticles would be a more safety and effective carrier for oral drug delivery.

Improvement of plastic optical fiber microphone based on moisture pattern sensing in devoiced breath

NASA Astrophysics Data System (ADS)

Taki, Tomohito; Honma, Satoshi; Morisawa, Masayuki; Muto, Shinzo

2008-03-01

Conversation is the most practical and common form in communication. However, people with a verbal handicap feel a difficulty to produce words due to variations in vocal chords. This research leads to develop a new devoiced microphone system based on distinguishes between the moisture patterns for each devoiced breaths, using a plastic optical fiber (POF) moisture sensor. In the experiment, five POF-type moisture sensors with fast response were fabricated by coating swell polymer with a slightly larger refractive index than that of fiber core and were set in front of mouth. When these sensors are exposed into humid air produced by devoiced breath, refractive index in cladding layer decreases by swelling and then the POF sensor heads change to guided type. Based on the above operation principle, the output light intensities from the five sensors set in front of mouth change each other. Using above mentioned output light intensity patterns, discernment of devoiced vowels in Japanese (a,i,u,e,o) was tried by means of DynamicProgramming-Matching (DP-matching) method. As the result, distinction rate over 90% was obtained to Japanese devoiced vowels. Therefore, using this system and a voice synthesizer, development of new microphone for the person with a functional disorder in the vocal chords seems to be possible.

Characterization of the modified nickel-zinc ferrite nanoparticles coated with APTES by salinization reaction

NASA Astrophysics Data System (ADS)

Zainal, Israa G.; Al-Shammari, Ahmed Majeed; Kachi, Wjeah

2018-05-01

Surface functionalization of magnetic iron oxide nanoparticles (NPs) is a kind of functional materials, which have been widely used in the biotechnology and catalysis. In this study, Nickel-Zinc ferrite nanoparticles was functionalized with amino propyl triethoxy silane (APTES) by silanization reaction and both non coated and organosilane-coated magnetite characterized by energy-dispersive X-ray spectroscopy (EDX), X-ray diffractometry, Fourier transformed infrared spectroscopy (FTIR) and atomic force microscopy. Basic groups of amino anchored on the external surface of the coated magnetite were observed. Our study procedure nanoparticles which have surface with free - NH2 groups which can carry out ionic interaction with carboxylic groups and act as a carrier of biological molecules, drugs and metals.

Microstructure-property relationships of chemically vapor deposited zirconia fiber coating for environmentally durable silicon carbide/silicon carbide composites

NASA Astrophysics Data System (ADS)

Li, Hao

In SiC/SiC ceramic matrix composites, toughness is obtained by adding a fiber coating, which provides a weak interface for crack deflection and debonding between the fiber and the matrix. However, the most commonly used fiber coatings, carbon and boron nitride, are unstable in oxidative environments. In the present study, the feasibility of using a chemically vapor deposited zirconia (CVD-ZrO2) fiber coating as an oxidation-resistant interphase for SiC/SiC composites was investigated. A study of morphological evolution in the CVD-ZrO2 coating suggested that a size-controlled displacive phase transformation from tetragonal ZrO2 ( t-ZrO2) to monoclinic ZrO2 (m-ZrO 2) was the key mechanism responsible for the weak interface behavior exhibited by the ZrO2 coating. It appeared that a low oxygen partial pressure in the CVD reactor chamber was essential for the nucleation of t-ZrO2 and therefore was responsible for the delamination behavior. With this understanding of the weak interface mechanism, minicomposite specimens containing various ZrO2 fiber coating morphologies were fabricated and tested. A fractographic analysis showed that in-situ fiber strength and minicomposite failure loads were strongly dependent on the phase contents and microstructure of the ZrO2 coating. We determined that an optimum microstructure of the ZrO2 coating should contain a predelaminated interface surrounded by a dense outer layer. The outer layer was needed to protect the fiber from degradation during the subsequent SiC matrix infiltration procedure. A preliminary tensile stress-rupture study indicated that the ZrO2 coating exhibited promising performance in terms of providing the weak interface behavior and maintaining the thermal and oxidative stability at elevated temperatures.

Study of the Production of a Metallic Coating on Natural Fiber Composite Through the Cold Spray Technique

NASA Astrophysics Data System (ADS)

Astarita, Antonello; Boccarusso, Luca; Durante, Massimo; Viscusi, Antonio; Sansone, Raffaele; Carrino, Luigi

2018-02-01

The deposition of a metallic coating on hemp-PLA (polylactic acid) laminate through the cold spray technique was studied in this paper. A number of different combinations of the deposition parameters were tested to investigate the feasibility of the process. The feasibility of the process was proved when processing conditions are properly set. The bonding mechanism between the substrate and the first layer of particles was studied through scanning electron microscope observations, and it was found that the polymeric matrix experiences a huge plastic deformation to accommodate the impinging particles; conversely a different mechanism was observed when metallic powders impact against a previously deposited metallic layer. The difference between the bonding mechanism and the growth of the coating was also highlighted. Depending on the spraying parameters, four different processing conditions were highlighted and discussed, and as a result the processing window was defined. The mechanical properties of the composite panel before and after the deposition were also investigated. The experiments showed that when properly carried out, the deposition process does not affect the strength of the panel; moreover, no improvements were observed because the contribution of the coating is negligible with respect to one of the reinforcement fibers.

Size-dependent in vivo toxicity of PEG-coated gold nanoparticles

PubMed Central

Zhang, Xiao-Dong; Wu, Di; Shen, Xiu; Liu, Pei-Xun; Yang, Na; Zhao, Bin; Zhang, Hao; Sun, Yuan-Ming; Zhang, Liang-An; Fan, Fei-Yue

2011-01-01

Background Gold nanoparticle toxicity research is currently leading towards the in vivo experiment. Most toxicology data show that the surface chemistry and physical dimensions of gold nanoparticles play an important role in toxicity. Here, we present the in vivo toxicity of 5, 10, 30, and 60 nm PEG-coated gold nanoparticles in mice. Methods Animal survival, weight, hematology, morphology, organ index, and biochemistry were characterized at a concentration of 4000 μg/kg over 28 days. Results The PEG-coated gold particles did not cause an obvious decrease in body weight or appreciable toxicity even after their breakdown in vivo. Biodistribution results show that 5 nm and 10 nm particles accumulated in the liver and that 30 nm particles accumulated in the spleen, while the 60 nm particles did not accumulate to an appreciable extent in either organ. Transmission electron microscopic observations showed that the 5, 10, 30, and 60 nm particles located in the blood and bone marrow cells, and that the 5 and 60 nm particles aggregated preferentially in the blood cells. The increase in spleen index and thymus index shows that the immune system can be affected by these small nanoparticles. The 10 nm gold particles induced an increase in white blood cells, while the 5 nm and 30 nm particles induced a decrease in white blood cells and red blood cells. The biochemistry results show that the 10 nm and 60 nm PEG-coated gold nanoparticles caused a significant increase in alanine transaminase and aspartate transaminase levels, indicating slight damage to the liver. Conclusion The toxicity of PEG-coated gold particles is complex, and it cannot be concluded that the smaller particles have greater toxicity. The toxicity of the 10 nm and 60 nm particles was obviously higher than that of the 5 nm and 30 nm particles. The metabolism of these particles and protection of the liver will be more important issues for medical applications of gold-based nanomaterials in future. PMID:21976982

Stability and magnetically induced heating behavior of lipid-coated Fe3O4 nanoparticles

NASA Astrophysics Data System (ADS)

Allam, Ayat A.; Sadat, Md Ehsan; Potter, Sarah J.; Mast, David B.; Mohamed, Dina F.; Habib, Fawzia S.; Pauletti, Giovanni M.

2013-10-01

Magnetic nanoparticles that are currently explored for various biomedical applications exhibit a high propensity to minimize total surface energy through aggregation. This study introduces a unique, thermoresponsive nanocomposite design demonstrating substantial colloidal stability of superparamagnetic Fe3O4 nanoparticles (SPIONs) due to a surface-immobilized lipid layer. Lipid coating was accomplished in different buffer systems, pH 7.4, using an equimolar mixture of 1,2-dipalmitoyl- sn-glycero-3-phosphocholine (DPPC) and l-α-dipalmitoylphosphatidyl glycerol (DPPG). Particle size and zeta potential were measured by dynamic laser light scattering. Heating behavior within an alternating magnetic field was compared between the commercial MFG-1000 magnetic field generator at 7 mT (1 MHz) and an experimental, laboratory-made magnetic hyperthermia system at 16.6 mT (13.7 MHz). The results revealed that product quality of lipid-coated SPIONs was significantly dependent on the colloidal stability of uncoated SPIONs during the coating process. Greatest stability was achieved at 0.02 mg/mL in citrate buffer (mean diameter = 80.0 ± 1.7 nm; zeta potential = -47.1 ± 2.6 mV). Surface immobilization of an equimolar DPPC/DPPG layer effectively reduced the impact of buffer components on particle aggregation. Most stable suspensions of lipid-coated nanoparticles were obtained at 0.02 mg/mL in citrate buffer (mean diameter = 179.3 ± 13.9 nm; zeta potential = -19.1 ± 2.3 mV). The configuration of the magnetic field generator significantly affected the heating properties of fabricated SPIONs. Heating rates of uncoated nanoparticles were substantially dependent on buffer composition but less influenced by particle concentration. In contrast, thermal behavior of lipid-coated nanoparticles within an alternating magnetic field was less influenced by suspension vehicle but dramatically more sensitive to particle concentration. These results underline the advantages of lipid-coated

Clinical prototype of a plastic water-equivalent scintillating fiber dosimeter array for QA applications.

PubMed

Lacroix, Fréderic; Archambault, Louis; Gingras, Luc; Guillot, Mathieu; Beddar, A Sam; Beaulieu, Luc

2008-08-01

A clinical prototype of a scintillating fiber dosimeter array for quality assurance applications is presented. The array consists of a linear array of 29 plastic scintillation detectors embedded in a water-equivalent plastic sheet coupled to optical fibers used to guide optical photons to a charge coupled device (CCD) camera. The CCD is packaged in a light-tight, radiation-shielded housing designed for convenient transport. A custom designed connector is used to ensure reproducible mechanical positioning of the optical fibers relative to the CCD. Profile and depth dose characterization measurements are presented and show that the prototype provides excellent dose measurement reproducibility (+/-0.8%) in-field and good accuracy (+/-1.6% maximum deviation) relative to the dose measured with an IC10 ionization chamber.

In vivo toxicity, biodistribution, and clearance of glutathione-coated gold nanoparticles.

PubMed

Simpson, Carrie A; Salleng, Kenneth J; Cliffel, David E; Feldheim, Daniel L

2013-02-01

Gold nanoparticles are emerging as promising materials from which to construct nanoscale therapeutics and therapeutic delivery systems. However, animal studies have shown that gold nanoparticles modified with certain thiol monolayers such as tiopronin can cause renal complications and morbidity. Although these effects may be eliminated by coadsorbing small amounts of polyethylene glycol (PEG) onto the nanoparticle surface, PEG can also lower cellular internalization efficiency and binding interactions with protein disease targets, significantly reducing the potential for using gold nanoparticles as therapeutics. Using ICP-MS analysis of blood, urine, and several organs, we show in this article that glutathione-coated gold nanoparticles (1.2 nm ± 0.9 nm) cause no morbidity at any concentration up to and including 60 μM and target primary organs although providing gradual dissipation and clearance over time. This study suggests that glutathione may be an attractive alternative to PEG in the design of gold nanoparticle therapeutics. This study describes the utility and toxicity of glutathione coated gold nanoparticles in comparison to PEGylated counterparts that are commonly used to increase "Stealth" properties and lower cytotoxicity. Too much PEG on the NPs can lead to lower cellular internalization efficiency and less efficient binding interactions with protein disease targets, significantly reducing the potential for using gold nanoparticles as therapeutics. Copyright © 2013 Elsevier Inc. All rights reserved.

Polysulfone coating for hollow fiber artificial lungs operated at hypobaric and hyperbaric pressures.

PubMed

High, K M; Snider, M T; Panol, G R; Richard, R B; Gray, D N

1996-01-01

Carbon dioxide transfer is increased when the gas phase of a hollow fiber membrane lung is operated at hypobaric pressures. Oxygen transfer is augmented by hyperbaric pressures. However, uncoated hollow fibers transmit gas bubbles into the blood when operated at a pressure greater than 800 mmHg and may have increased plasma leakage when operated at hypobaric pressures. Ultrathin polymer coatings may avoid this problem while reducing thrombogenicity. The authors coated microporous polypropylene hollow fibers with 380 microns outer diameter and 50 microns walls using 1, 2, 3, and 4% solutions of polysulfone in tetrahydrofuran by dipping or continuous pull through. These fibers were mounted in small membrane lung prototypes having surface areas of 70 and 187 cm2. In gas-to-gas testing, the longer the exposure time to the solution and the greater the polymer concentration, the less the permeation rate. The 3% solutions blocked bulk gas flow. The coating was 1 micron thick by mass balance calculations. During water-to-gas tests, hypobaric gas pressures of 40 mmHg absolute were tolerated, but CO2 transfer was reduced to 40% of the bare fibers. Hyperbaric gas pressures of 2,100 mmHg absolute tripled O2 transfer without bubble formation.

Low temperature and UV curable sol-gel coatings for long lasting optical fiber biosensors

NASA Astrophysics Data System (ADS)

Otaduy, D.; Villar, A.; Gomez-Herrero, E.; Goitandia, A. M.; Gorritxategi, E.; Quintana, I.

2010-04-01

The use of optical fibers as sensing element is increasing in clinical, pharmaceutical and industrial applications. Excellent light delivery, long interaction length, low cost and ability not only to excite the target molecules but also to capture the emitted light from the targets are the hallmarks of optical fiber as biosensors. In biosensors based on fiber optics the interaction with the analyte can occur within an element of the optical fiber. One of the techniques for this kind of biosensors is to remove the fiber optic cladding and substitute it for biological coatings that will interact with the parameter to sensorize. The deposition of these layers can be made by sol-gel technology. The sol-gel technology is being increasingly used mainly due to the high versatility to tailor their optical features. Incorporation of suitable chemical and biochemical sensing agents have allowed determining pH, gases, and biochemical species, among others. Nonetheless, the relatively high processing temperatures and short lifetime values mean severe drawbacks for a successful exploitation of sol-gel based coated optical fibres. With regard to the latter, herein we present the design, preparation and characterization of novel sol-gel coated optical fibres. Low temperature and UV curable coating formulations were optimized to achieve a good adhesion and optical performance. The UV photopolymerizable formulation was comprised by glycidoxypropyltrimethoxysilane (GLYMO), Tetraethylorthosilicate (TEOS) and an initiator. While the thermoset coating was prepared by using 3-aminopropyltrimethoxysilane, GLYMO, and TEOS as main reagents. Both curable sol-gel coated fibres were analysed by FTIR, SEM and optical characterization. Furthermore, in the present work a new technique for silica cladding removal has been developed by ultra-short pulses laser processing, getting good dimensional accuracy and surface integrity.

Temperature and refractive index measurement based on a coating-enhanced dual-microspheric fiber sensor

NASA Astrophysics Data System (ADS)

Ju, Yao; Ning, Shougui; Sun, Huijin; Mo, Jun; Yang, Chao; Feng, Guoying; Zhou, Hao; Zhou, Shouhuan

2018-07-01

We propose and demonstrate a coating-enhanced dual-microspheric structure fiber sensor that measures temperature and refractive index simultaneously. The claddings of the two microspheric structured fibers are spliced together and the ends of the fibers are coated with a layer of gold film to increase reflection, thereby forming a dual-microspheric structure sensor head. Our experimental results show that the temperature sensitivity and the refractive index can reach 65.77 pm °C‑1 and  ‑19.7879 nm RIU‑1, respectively. Compared with the uncoated sensor, the refractive index sensitivity is significantly improved by the gold film. This work suggests a low-cost, high-resolution and convenient fiber-based method to achieve multifunctional sensing applications.

1550 nm modulating retroreflector based on coated nanoparticles for free-space optical communication.

PubMed

Rosenkrantz, Etai; Arnon, Shlomi

2015-06-10

Nowadays, there is a renaissance in the field of space exploration. Current and future missions depend on astronauts and a swarm of robots for reconnaissance. In order to reduce the power consumption, weight, and size of the robots, an asymmetric communication system may be used. This is achieved by installing modulating retroreflectors (MRRs) on one side of the link and an interrogating laser on the other side. In this paper, we theoretically study an innovative device that can serve as an MRR in the infrared range of the spectrum. The device is based on a ferroelectric PZT thin film containing TiO₂ coated Ag nanoparticles, which exhibit strong plasmonic resonance in the infrared range. After intensive analyses, which included calculations and simulations, we were able to design the device to operate at the 1550 nm wavelength. This is of great importance since the design of devices operating at 1550 nm as this wavelength is a mature technology widely used in free-space optics. Hence, this MRR can serve in asymmetric communication links relying on 1550 nm transmissions, which are also eye-safe. To the best of our knowledge, this is the first time coated metal nanoparticles have been proposed to modulate light in the infrared region. The performance of this device is unique, reaching a 17.5 dB modulation contrast with only a ±2 V operating voltage. This modulator may also be used for terrestrial communication such as fiber optics and optical interconnects in future data centers.

Tuning dipolar magnetic interactions by controlling individual silica coating of iron oxide nanoparticles

NASA Astrophysics Data System (ADS)

Rivas Rojas, P. C.; Tancredi, P.; Moscoso Londoño, O.; Knobel, M.; Socolovsky, L. M.

2018-04-01

Single and fixed size core, core-shell nanoparticles of iron oxides coated with a silica layer of tunable thickness were prepared by chemical routes, aiming to generate a frame of study of magnetic nanoparticles with controlled dipolar interactions. The batch of iron oxides nanoparticles of 4.5 nm radii, were employed as cores for all the coated samples. The latter was obtained via thermal decomposition of organic precursors, resulting on nanoparticles covered with an organic layer that was subsequently used to promote the ligand exchange in the inverse microemulsion process, employed to coat each nanoparticle with silica. The amount of precursor and times of reaction was varied to obtain different silica shell thicknesses, ranging from 0.5 nm to 19 nm. The formation of the desired structures was corroborated by TEM and SAXS measurements, the core single-phase spinel structure was confirmed by XRD, and superparamagnetic features with gradual change related to dipolar interaction effects were obtained by the study of the applied field and temperature dependence of the magnetization. To illustrate that dipolar interactions are consistently controlled, the main magnetic properties are presented and analyzed as a function of center to center minimum distance between the magnetic cores.

Thin film transistors on plastic substrates with reflective coatings for radiation protection

DOEpatents

Wolfe, Jesse D.; Theiss, Steven D.; Carey, Paul G.; Smith, Patrick M.; Wickboldt, Paul

2003-11-04

Fabrication of silicon thin film transistors (TFT) on low-temperature plastic substrates using a reflective coating so that inexpensive plastic substrates may be used in place of standard glass, quartz, and silicon wafer-based substrates. The TFT can be used in large area low cost electronics, such as flat panel displays and portable electronics such as video cameras, personal digital assistants, and cell phones.

Thin film transistors on plastic substrates with reflective coatings for radiation protection

DOEpatents

Wolfe, Jesse D [Fairfield, CA; Theiss, Steven D [Woodbury, MN; Carey, Paul G [Mountain View, CA; Smith, Patrick M [San Ramon, CA; Wickbold, Paul [Walnut Creek, CA

2006-09-26

Fabrication of silicon thin film transistors (TFT) on low-temperature plastic substrates using a reflective coating so that inexpensive plastic substrates may be used in place of standard glass, quartz, and silicon wafer-based substrates. The TFT can be used in large area low cost electronics, such as flat panel displays and portable electronics such as video cameras, personal digital assistants, and cell phones.

Multipositional silica-coated silver nanoparticles for high-performance polymer solar cells.

PubMed

Choi, Hyosung; Lee, Jung-Pil; Ko, Seo-Jin; Jung, Jae-Woo; Park, Hyungmin; Yoo, Seungmin; Park, Okji; Jeong, Jong-Ryul; Park, Soojin; Kim, Jin Young

2013-05-08

We demonstrate high-performance polymer solar cells using the plasmonic effect of multipositional silica-coated silver nanoparticles. The location of the nanoparticles is critical for increasing light absorption and scattering via enhanced electric field distribution. The device incorporating nanoparticles between the hole transport layer and the active layer achieves a power conversion efficiency of 8.92% with an external quantum efficiency of 81.5%. These device efficiencies are the highest values reported to date for plasmonic polymer solar cells using metal nanoparticles.

Characterization and Effects of Fiber Pull-Outs in Hole Quality of Carbon Fiber Reinforced Plastics Composite

PubMed Central

Alizadeh Ashrafi, Sina; Miller, Peter W.; Wandro, Kevin M.; Kim, Dave

2016-01-01

Hole quality plays a crucial role in the production of close-tolerance holes utilized in aircraft assembly. Through drilling experiments of carbon fiber-reinforced plastic composites (CFRP), this study investigates the impact of varying drilling feed and speed conditions on fiber pull-out geometries and resulting hole quality parameters. For this study, hole quality parameters include hole size variance, hole roundness, and surface roughness. Fiber pull-out geometries are quantified by using scanning electron microscope (SEM) images of the mechanically-sectioned CFRP-machined holes, to measure pull-out length and depth. Fiber pull-out geometries and the hole quality parameter results are dependent on the drilling feed and spindle speed condition, which determines the forces and undeformed chip thickness during the process. Fiber pull-out geometries influence surface roughness parameters from a surface profilometer, while their effect on other hole quality parameters obtained from a coordinate measuring machine is minimal. PMID:28773950

Biocompatible Polysiloxane-Containing Diblock Copolymer PEO-b-PγMPS for Coating Magnetic Nanoparticles

PubMed Central

Chen, Hongwei; Wu, Xinying; Duan, Hongwei; Wang, Y. Andrew; Wang, Liya; Zhang, Minming; Mao, Hui

2009-01-01

We report a biocompatible polysiloxane containing amphiphilic diblock copolymer, poly(ethylene oxide)-block-poly(γ-methacryloxypropyltrimethoxysilane) (PEO-b-PγMPS), for coating and stabilizing nanoparticles for biomedical applications. Such amphiphilic diblock copolymer which comprises both a hydrophobic segment with “surface anchoring moiety” (silane group) and a hydrophilic segment with PEO (Mn=5000 g/mol) was obtained by the reversible addition fragmentation chain transfer (RAFT) polymerization using the PEO macromolecular chain transfer agent. When used for coating paramagnetic iron oxide nanoparticles (IONPs), copolymers were mixed with hydrophobic oleic acid coated core size uniformed IONPs (D=13 nm) in co-solvent tetrahydrofuran. After being aged over a period of time, resulting monodispersed IONPs can be transferred into aqueous medium. With proper PγMPS block length (Mn=10,000 g/mol), polysiloxane containing diblock copolymers formed a thin layer of coating (~3 nm) around monocrystalline nanoparticles as measured by transmission electron microscopy (TEM). Magnetic resonance imaging (MRI) experiments showed excellent T2 weighted contrast effect from coated IONPs with a transverse relaxivity r2=98.6 mM−1s−1 (at 1.5 Tesla). Such thin coating layer has little effect on the relaxivity when compared to that of IONPs coated with conventional amphiphilic copolymer. Polysiloxane containing diblock copolymer coated IONPs are stable without aggregation or binding to proteins in serum when incubated for 24 h in culture medium containing 10% serum. Furthermore, much lower level of intracellular uptake by macrophage cells was observed with polysiloxane containing diblock copolymers coated IONPs, suggesting the reduction of non-specific cell uptakes and antibiofouling effect. PMID:20161520

Effects of Temperature and X-rays on Plastic Scintillating Fiber and Infrared Optical Fiber

PubMed Central

Lee, Bongsoo; Shin, Sang Hun; Jang, Kyoung Won; Yoo, Wook Jae

2015-01-01

In this study, we have studied the effects of temperature and X-ray energy variations on the light output signals from two different fiber-optic sensors, a fiber-optic dosimeter (FOD) based on a BCF-12 as a plastic scintillating fiber (PSF) and a fiber-optic thermometer (FOT) using a silver halide optical fiber as an infrared optical fiber (IR fiber). During X-ray beam irradiation, the scintillating light and IR signals were measured simultaneously using a dosimeter probe of the FOD and a thermometer probe of the FOT. The probes were placed in a beaker with water on the center of a hotplate, under variation of the tube potential of a digital radiography system or the temperature of the water in the beaker. From the experimental results, in the case of the PSF, the scintillator light output at the given tube potential decreased as the temperature increased in the temperature range from 25 to 60 °C. We demonstrated that commonly used BCF-12 has a significant temperature dependence of −0.263 ± 0.028%/°C in the clinical temperature range. Next, in the case of the IR fiber, the intensity of the IR signal was almost uniform at each temperature regardless of the tube potential range from 50 to 150 kVp. Therefore, we also demonstrated that the X-ray beam with an energy range used in diagnostic radiology does not affect the IR signals transmitted via a silver halide optical fiber. PMID:25970257

LSMO Nanoparticles Coated by Hyaluronic Acid for Magnetic Hyperthermia

NASA Astrophysics Data System (ADS)

Chen, Yuanwei; Wang, Ying; Liu, Xi; Lu, Mai; Cao, Jiangwei; Wang, Tao

2016-12-01

Magnetic hyperthermia with the treating temperature range of 41-46 °C is an alternative therapy for cancer treatment. In this article, lanthanum strontium manganates (La1- x Sr x MnO3, 0.25 ≤ × ≤ 0.35) magnetic nanoparticles coated by hyaluronic acid (HA) which possesses the ability of targeting tumor cells were prepared by a simple hydrothermal method combined with a high-energy ball milling technique. The crystal structure, morphology, magnetic properties of the HA-coated magnetic nanoparticles (MNPs), and their heating ability under alternating magnetic field were investigated. It was found the HA-coated La0.7Sr0.3MnO3, with particle diameter of 100 nm, Curie temperature of 45 °C at a concentration 6 mg/ml, gave the optimal induction heating results. The heating temperature saturates at 45.7 °C, and the ESAR is 5.7 × 10-3 W/g · kHz · (kA/m2) which is much higher than other reported results.

Initial study of sediment antagonism and characteristics of silver nanoparticle-coated biliary stents in an experimental animal model.

PubMed

Tian, Yigeng; Xia, Mingfeng; Zhang, Shuai; Fu, Zhen; Wen, Qingbin; Liu, Feng; Xu, Zongzhen; Li, Tao; Tian, Hu

2016-01-01

Plastic biliary stents used to relieve obstructive jaundice are frequently blocked by sediment, resulting in loss of drainage. We prepared stents coated with silver nanoparticles (AgNPs) and compared their ability to resist sedimentation with Teflon stents in a beagle model of obstructive jaundice. AgNP-coated Teflon biliary stents were prepared by chemical oxidation-reduction and evaluated in an obstructive jaundice model that was produced by ligation of common bile duct (CBD); animals were randomized to two equal groups for placement of AgNP-coated or Teflon control stents. Liver function and inflammatory index were found to be similar in the two groups, and the obstruction was relieved. Stents were removed 21 days after insertion and observed by scanning and transmission electron microscopy. The AgNP coating was analyzed by energy dispersive X-ray analysis (EDXA), and the composition of sediment was assayed by Fourier-transform infrared (FTIR) spectroscopy. Electron microscopy revealed a black, closely adherent AgNP stent coating, with thicknesses of 1.5-6 µm. Sediment thickness and density were greater on Teflon than on AgNP-coated stents. EDXA confirmed the stability and integrity of the AgNP coating before and after in vivo animal experimentation. FTIR spectroscopy identified stent sediment components including bilirubin, cholesterol, bile acid, protein, calcium, and other substances. AgNP-coated biliary stents resisted sediment accumulation in this canine model of obstructive jaundice caused by ligation of the CBD.

Initial study of sediment antagonism and characteristics of silver nanoparticle-coated biliary stents in an experimental animal model

PubMed Central

Tian, Yigeng; Xia, Mingfeng; Zhang, Shuai; Fu, Zhen; Wen, Qingbin; Liu, Feng; Xu, Zongzhen; Li, Tao; Tian, Hu

2016-01-01

Objective Plastic biliary stents used to relieve obstructive jaundice are frequently blocked by sediment, resulting in loss of drainage. We prepared stents coated with silver nanoparticles (AgNPs) and compared their ability to resist sedimentation with Teflon stents in a beagle model of obstructive jaundice. Methods AgNP-coated Teflon biliary stents were prepared by chemical oxidation–reduction and evaluated in an obstructive jaundice model that was produced by ligation of common bile duct (CBD); animals were randomized to two equal groups for placement of AgNP-coated or Teflon control stents. Liver function and inflammatory index were found to be similar in the two groups, and the obstruction was relieved. Stents were removed 21 days after insertion and observed by scanning and transmission electron microscopy. The AgNP coating was analyzed by energy dispersive X-ray analysis (EDXA), and the composition of sediment was assayed by Fourier-transform infrared (FTIR) spectroscopy. Results Electron microscopy revealed a black, closely adherent AgNP stent coating, with thicknesses of 1.5–6 µm. Sediment thickness and density were greater on Teflon than on AgNP-coated stents. EDXA confirmed the stability and integrity of the AgNP coating before and after in vivo animal experimentation. FTIR spectroscopy identified stent sediment components including bilirubin, cholesterol, bile acid, protein, calcium, and other substances. Conclusion AgNP-coated biliary stents resisted sediment accumulation in this canine model of obstructive jaundice caused by ligation of the CBD. PMID:27217749

X-ray detection properties of plastic scintillators containing surface-modified Bi2O3 nanoparticles

NASA Astrophysics Data System (ADS)

Hiyama, Fumiyuki; Noguchi, Takio; Koshimizu, Masanori; Kishimoto, Shunji; Haruki, Rie; Nishikido, Fumihiko; Fujimoto, Yutaka; Aida, Tsutomu; Takami, Seiichi; Adschiri, Tadafumi; Asai, Keisuke

2018-05-01

Plastic scintillators containing Bi2O3 nanoparticles (NPs) were developed as detectors for X-ray synchrotron radiation. A hydrothermal method was used to synthesize the NPs that had average particle sizes of less than 10 nm. Higher NP concentration led to a higher detection efficiency at 67.4 keV. The light yield of the scintillator containing 5 wt % Bi2O3 NPs was comparable with or higher than that of the commercially available plastic scintillator, EJ 256. The time resolution of the developed scintillation detector equipped with each sample scintillator was approximately 0.6 ns. Dispersion of nanoparticles within plastic scintillators is generally applicable and has wide application as a method for preparation of plastic scintillators for detecting X-ray synchrotron radiation.

Combined synthesis and in situ coating of nanoparticles in the gas phase

NASA Astrophysics Data System (ADS)

Lähde, Anna; Raula, Janne; Kauppinen, Esko I.

2008-12-01

Combined gas phase synthesis and coating of sodium chloride (NaCl) and lactose nanoparticles has been developed using an aerosol flow reactor. Nano-sized core particles were produced by the droplet-to-particle method and coated in situ by the physical vapour deposition of L-leucine vapour. The saturation of L-leucine in the reactor determined the resulting particle size and size distribution. In general, particle size increased with the addition of L-leucine and notable narrowing of the core particle size distribution was observed. In addition, homogeneous nucleation of the vapour, i.e. formation of pure L-leucine particles, was observed depending on the saturation conditions of L-leucine as well as the core particle characteristics. The effects of core particle properties, i.e. size and solid-state characteristics, on the coating process were studied by comparing the results for coated NaCl and lactose particles. During deposition, L-leucine formed a uniform coating on the surface of the core particles. The coating stabilised the nanoparticles and prevented the sintering of particles during storage.

Multifunctional gold coated iron oxide core-shell nanoparticles stabilized using thiolated sodium alginate for biomedical applications.

PubMed

Sood, Ankur; Arora, Varun; Shah, Jyoti; Kotnala, R K; Jain, Tapan K

2017-11-01

In this paper we report synthesis of aqueous based gold coated iron oxide nanoparticles to integrate the localized surface plasma resonance (SPR) properties of gold and magnetic properties of iron oxide in a single system. Iron oxide-gold core shell nanoparticles were stabilized by attachment of thiolated sodium alginate to the surface of nanoparticles. Transmission electron microscope (TEM) micrograph presents an average elementary particle size of 8.1±2.1nm. High resolution TEM (HR-TEM) and X-ray photon spectroscopy further confirms the presence of gold shell around iron oxide core. Gold coating is responsible for reducing saturation magnetization (M s ) value from ~41emu/g to ~24emu/g - in thiolated sodium alginate stabilized gold coated iron oxide core-shell nanoparticles. The drug (curcumin) loading efficiency for the prepared nanocomposites was estimated to be around 7.2wt% (72μgdrug/mg nanoparticles) with encapsulation efficiency of 72.8%. Gold-coated iron oxide core-shell nanoparticles could be of immense importance in the field of targeted drug delivery along with capability to be used as contrast agent for MRI & CT. Copyright © 2017 Elsevier B.V. All rights reserved.

Dye surface coating enables visible light activation of TiO2 nanoparticles leading to degradation of neighboring biological structures.

PubMed

Blatnik, Jay; Luebke, Lanette; Simonet, Stephanie; Nelson, Megan; Price, Race; Leek, Rachael; Zeng, Leyong; Wu, Aiguo; Brown, Eric

2012-02-01

Biologically and chemically modified nanoparticles are gaining much attention as a new tool in cancer detection and treatment. Herein, we demonstrate that an alizarin red S (ARS) dye coating on TiO2 nanoparticles enables visible light activation of the nanoparticles leading to degradation of neighboring biological structures through localized production of reactive oxygen species. Successful coating of nanoparticles with dye is demonstrated through sedimentation, spectrophotometry, and gel electrophoresis techniques. Using gel electrophoresis, we demonstrate that visible light activation of dye-TiO2 nanoparticles leads to degradation of plasmid DNA in vitro. Alterations in integrity and distribution of nuclear membrane associated proteins were detected via fluorescence confocal microscopy in HeLa cells exposed to perinuclear localized ARS-TiO2 nanoparticles that were photoactivated with visible light. This study expands upon previous studies that indicated dye coatings on TiO2 nanoparticles can serve to enhance imaging, by clearly showing that dye coatings on TiO2 nanoparticles can also enhance the photoreactivity of TiO2 nanoparticles by allowing visible light activation. The findings of our study suggest a therapeutic application of dye-coated TiO2 nanoparticles in cancer research; however, at the same time they may reveal limitations on the use of dye assisted visualization of TiO2 nanoparticles in live-cell imaging.

Magnetic nanoparticles coated with polyaniline to stabilize immobilized trypsin

NASA Astrophysics Data System (ADS)

Maciel, J. C.; D. Mercês, A. A.; Cabrera, M.; Shigeyosi, W. T.; de Souza, S. D.; Olzon-Dionysio, M.; Fabris, J. D.; Cardoso, C. A.; Neri, D. F. M.; C. Silva, M. P.; Carvalho, L. B.

2016-12-01

It is reported the synthesis of magnetic nanoparticles via the chemical co-precipitation of Fe 3+ ions and their preparation by coating them with polyaniline. The electronic micrograph analysis showed that the mean diameter for the nanoparticles is ˜15 nm. FTIR, powder X-ray diffraction and Mössbauer spectroscopy were used to understand the chemical, crystallographic and 57Fe hyperfine structures for the two samples. The nanoparticles, which exhibited magnetic behavior with relatively high spontaneous magnetization at room temperature, were identified as being mainly formed by maghemite ( γFe2O3). The coated magnetic nanoparticles (sample labeled "mPANI") presented a real ability to bind biological molecules such as trypsin, forming the magnetic enzyme derivative (sample "mPANIG-Trypsin"). The amount of protein and specific activity of the immobilized trypsin were found to be 13±5 μg of protein/mg of mPANI (49.3 % of immobilized protein) and 24.1±0.7 U/mg of immobilized protein, respectively. After 48 days of storage at 4 ∘C, the activity of the immobilized trypsin was found to be 89 % of its initial activity. This simple, fast and low-cost procedure was revealed to be a promising way to prepare mPANI nanoparticles if technological applications addressed to covalently link biomolecules are envisaged. This route yields chemically stable derivatives, which can be easily recovered from the reaction mixture with a magnetic field and recyclable reused.

Titania-coated manganite nanoparticles: Synthesis of the shell, characterization and MRI properties

NASA Astrophysics Data System (ADS)

Jirák, Zdeněk; Kuličková, Jarmila; Herynek, Vít; Maryško, Miroslav; Koktan, Jakub; Kaman, Ondřej

2017-04-01

Novel procedure for coating of oxide nanoparticles with titania, employing hydrolysis and polycondensation of titanium alkoxides under high-dilution conditions and cationic surfactants, is developed and applied to magnetic cores of perovskite manganite. Bare particles of the ferromagnetic La0.65Sr0.35MnO3 phase, possessing high magnetization, M10 kOe(4.5 K) = 63.5 emu g-1, and Curie temperature, TC = 355 K, are synthesized by sol-gel procedure and subsequently coated with titania. Further, a comparative silica-coated product is prepared. In order to analyse the morphology, colloidal stability, and surface properties of these two types of coated particles, a detailed study by means of transmission electron microscopy, dynamic light scattering, zeta-potential measurements, and IR spectroscopy is carried out. The experiments on the titania-coated sample reveal a continuous though porous character of the TiO2 shell, the nature of which is amorphous but can be transformed to anatase at higher temperatures. Finally, the relaxometric study at the magnetic field of 0.5 T, performed to quantity the transverse relaxivity and its temperature dependence, reveals important differences between the titania-coated and silica-coated nanoparticles.

Development of new magnetic nanoparticles: Oligochitosan obtained by γ-rays and -coated Fe3O4 nanoparticles

NASA Astrophysics Data System (ADS)

Le Thi, Thao Nguyen; Nguyen, Thi Hiep; Hoang, Dong Quy; Tran, Tuong, Vi; Nguyen, Ngoc Thuy; Nguyen, Dai Hai

2017-11-01

Oligochitosan (OCS) have been utilized as a potential bioactive material for improving food quality and human health. In this study, superparamagnetic iron oxide (Fe3O4) nanoparticles were originally coated with OCS irradiated by gamma rays for their possible biomedical applications. The formation of Fe3O4@OCS was characterized by Fourier transform infrared (FT-IR), X-ray diffraction patterns (XRD), energy dispersive X-ray spectroscopy (EDS) and thermogravimetric analysis (TGA). In addition, the superparamagnetic properties and sizes and morphologies of Fe3O4 and Fe3O4@OCS nanoparticles were demonstrated by vibrating sample magnetometer (VSM) and transmission electron microscopy (TEM), respectively. These results indicated that Fe3O4@OCS nanoparticles still maintained their superparamagnetic properties after polymeric coating, and were nearly spherical in shape with average diameter of 14.4 ± 0.31 nm, compared with 11.8 ± 0.52 nm of bare Fe3O4 nanoparticles, respectively. As a result, Fe3O4@OCS nanoparticles may serve as a promising platform for the development of new magnetic materials, which could be useful for biomedical applications.

Cross-linked gelatin/nanoparticles composite coating on micro-arc oxidation film for corrosion and drug release

NASA Astrophysics Data System (ADS)

Xu, Xinhua; Lu, Ping; Guo, Meiqing; Fang, Mingzhong

2010-02-01

A composite coating which could control drug release and biocorrosion of magnesium alloy stent materials WE42 was prepared. This composite coating was fabricated on the surface of the micro-arc oxidation (MAO) film of the magnesium alloy, WE42, by mixing different degrees of cross-linked gelatin with well-dispersed poly( DL-lactide-co-glycolide) (PLGA) nanoparticles. The PLGA nanoparticles were prepared by emulsion solvent evaporation/extraction technique. Nano ZS laser diffraction particle size analyzer detected that the size of the nanoparticles to be 150-300 nm. Scanning electron microscopy (SEM) and atomic force microscopy (AFM) was used to analyze the morphology of the nanoparticles and the composite coating. Potentiodynamic polarization and electrochemical impedance spectroscopy (EIS) were used to evaluate the corrosion behavior of the composite coating. Drug release was determined by ultraviolet-visible (UV-vis) spectrophotometer. The corrosion resistance of the composite coating was improved by preventing the corrosive ions from diffusing to the MAO films. The drug release rate of paclitaxel (PTX) exhibited a nearly linear sustained-release profile with no significant burst releases.

Characterization of QCM sensor surfaces coated with molecularly imprinted nanoparticles.

PubMed

Reimhult, Kristina; Yoshimatsu, Keiichi; Risveden, Klas; Chen, Si; Ye, Lei; Krozer, Anatol

2008-07-15

Molecularly imprinted polymers (MIPs) are gaining great interest as tailor-made recognition materials for the development of biomimetic sensors. Various approaches have been adopted to interface MIPs with different transducers, including the use of pre-made imprinted particles and the in situ preparation of thin polymer layers directly on transducer surfaces. In this work we functionalized quartz crystal microbalance (QCM) sensor crystals by coating the sensing surfaces with pre-made molecularly imprinted nanoparticles. The nanoparticles were immobilized on the QCM transducers by physical entrapment in a thin poly(ethylene terephthalate) (PET) layer that was spin-coated on the transducer surface. By controlling the deposition conditions, it was possible to gain a high nanoparticle loading in a stable PET layer, allowing the recognition sites in nanoparticles to be easily accessed by the test analytes. In this work, different sensor surfaces were studied by micro-profilometry and atomic force microscopy and the functionality was evaluated using quartz crystal microbalance with dissipation (QCM-D). The molecular recognition capability of the sensors were also confirmed using radioligand binding analysis by testing their response to the presence of the test compounds, (R)- and (S)-propranolol in aqueous buffer.

Precise micropatterning of silver nanoparticles on plastic substrates

NASA Astrophysics Data System (ADS)

Ammosova, Lena; Jiang, Yu; Suvanto, Mika; Pakkanen, Tapani A.

2017-04-01

Conventional fabrication methods to obtain metal patterns on polymer substrates are restricted by high operating temperature and complex preparation steps. The present study demonstrates a simple yet versatile method for preparation of silver nanoparticle micropatterns on polymer substrates with various surface geometry. With the microworking robot technique, we were able not only to directly structure the surface, but also precisely deposit silver nanoparticle ink on the desired surface location with the minimum usage of ink material. The prepared silver nanoparticle ink, containing silver cations and polyethylene glycol (PEG) as a reducing agent, yields silver nanoparticle micropatterns on plastic substrates at low sintering temperature without any contamination. The influence of the ink behaviour was studied, such as substrate wettability, ink volume, and sintering temperature. The ultraviolet visible (UV-vis), scanning electron microscopy (SEM), and energy dispersive spectroscopy (EDS) measurements revealed the formation of micropatterns with uniformly distributed silver nanoparticles. The prepared patterns are expected to have a broad range of applications in optics, medicine, and sensor devices owing to the unique properties of silver. Furthermore, the deposition of a chemical compound, which is different from the substrate material, not only adds a fourth dimension to the prestructured three-dimensional (3D) surfaces, but also opens new application areas to the conventional surface structures.

A protocol for the production of gliadin-cyanoacrylate nanoparticles for hydrophilic coating

USDA-ARS?s Scientific Manuscript database

This article presents a protocol for the production of protein-based nanoparticles that change the hydrophobic surface to hydrophilic by a simple spray coating. These nanoparticles are produced by the polymerization reaction of alkyl cyanoacrylate on the surface of cereal protein (gliadin) molecules...

Magnetite Nanoparticles Coated with Rifampicin and Chlortetracycline for Drug Delivery Applications

NASA Astrophysics Data System (ADS)

Nǎdejde, Claudia; Ciurlicǎ, Ecaterina Foca-nici; Creangǎ, Dorina; Cârlescu, Aurelian; Bǎdescu, Vasile

2010-12-01

Four types of biocompatible magnetic fluids based on superparamagnetic nanoparticles with Fe3O4 cores were functionalized with antibiotics (rifampicin or chlortetracycline) as potential candidates for in vivo biomedical applications, such as magnetically controlled drug delivery. The synthesis consisted in coprecipitation of iron oxide in basic, as well as in acid medium, followed by the dispersion of the resulted magnetite nanoparticles in aqueous solution containing the antibiotic. The chosen method to prepare the magnetite-core/drug-shell systems avoided intermediate organic coating of the magnetic nanoparticles. Comparative analysis of the rheological features of the aqueous magnetic fluid samples was performed. The structural features of the coated magnetic particles were investigated by X-Ray Diffraction (XRD), Transmission Electron Microscopy (TEM) and Vibrating Sample Magnetometry (VSM). Good crystallinity and adequate stability in time were evidenced. Drug delivery curves were spectrophotometrically provided.

Growth of textured thin Au coatings on iron oxide nanoparticles with near infrared absorbance

PubMed Central

Ma, L L; Borwankar, A U; Willsey, B W; Yoon, K Y; Tam, J O; Sokolov, K V; Feldman, M D; Milner, T E; Johnston, K P

2013-01-01

A homologous series of Au-coated iron oxide nanoparticles, with hydrodynamic diameters smaller than 60 nm was synthesized with very low Auto-iron mass ratios as low as 0.15. The hydrodynamic diameter was determined by dynamic light scattering and the composition by atomic absorption spectroscopy and energy dispersive x-ray spectroscopy (EDS). Unusually low Au precursor supersaturation levels were utilized to nucleate and grow Au coatings on iron oxide relative to formation of pure Au nanoparticles. This approach produced unusually thin coatings, by lowering autocatalytic growth of Au on Au, as shown by transmission electron microscopy (TEM). Nearly all of the nanoparticles were attracted by a magnet indicating a minimal amount of pure Au particles The coatings were sufficiently thin to shift the surface plasmon resonance (SPR) to the near infrared (NIR), with large extinction coefficients., despite the small particle hydrodynamic diameters, observed from dynamic light scattering to be less than 60 nm. PMID:23238021

Dielectric strength of irradiated fiber reinforced plastics