Suppression of NaNO3 crystal nucleation by glycerol: micro-Raman observation on the efflorescence process of mixed glycerol/NaNO3/water droplets.

PubMed

Yu, Jun-Ying; Zhang, Yun; Zeng, Guang; Zheng, Chuan-Ming; Liu, Yong; Zhang, Yun-Hong

2012-02-09

Although the hygroscopicity of a NaNO(3)/water microdroplet and a polyalcohol/water microdroplet, two of the most important aerosols in atmosphere, has been widely studied, little is known about the relationship between the hygroscopic behavior of mixed NaNO(3)/polyalcohol/water droplets and their structures on the molecular level. In this study, the hygroscopicity of mixed glycerol/NaNO(3)/water droplets deposited on a hydrophobic substrate was studied by micro-Raman spectroscopy with organic-to-inorganic molar ratios (OIRs) of 0.5, 1, and 2. In the mixed glycerol/NaNO(3)/water droplets, glycerol molecules tended to combine with Na(+) and NO(3)(-) ions by electrostatic interaction and hydrogen bonding, respectively. On the basis of the analyses of the changes of symmetric stretching (v(s)-CH(2)), asymmetric stretching (v(a)-CH(2)), their area ratio (Av(a)-CH(2)/Av(s)-CH(2)) of glycerol, and symmetric stretching band of NO(3)(-) (ν(1)-NO(3)(-)) with relative humidity (RH), it was found that the conformation of glycerol was transformed from αα mainly to γγ and partly to αγ with a decreasing RH in the mixed droplets, contrary to the case in the glycerol/water droplet. In addition, the glycerol with γγ and αγ conformation had strong interaction with Na(+) and NO(3)(-) respectively, which suppressed the formation of contact of ions and delayed the efflorescence relative humidity (ERH) for the mixed droplets compared to the NaNO(3)/water droplet. © 2012 American Chemical Society

Fabrication and condensation characteristics of metallic superhydrophobic surface with hierarchical micro-nano structures

NASA Astrophysics Data System (ADS)

Chu, Fuqiang; Wu, Xiaomin

2016-05-01

Metallic superhydrophobic surfaces have various applications in aerospace, refrigeration and other engineering fields due to their excellent water repellent characteristics. This study considers a simple but widely applicable fabrication method using a two simultaneous chemical reactions method to prepare the acid-salt mixed solutions to process the metal surfaces with surface deposition and surface etching to construct hierarchical micro-nano structures on the surface and then modify the surface with low surface-energy materials. Al-based and Cu-based superhydrophobic surfaces were fabricated using this method. The Al-based superhydrophobic surface had a water contact angle of 164° with hierarchical micro-nano structures similar to the lotus leaves. The Cu-based surface had a water contact angle of 157° with moss-like hierarchical micro-nano structures. Droplet condensation experiments were also performed on these two superhydrophobic surfaces to investigate their condensation characteristics. The results show that the Al-based superhydrophobic surface has lower droplet density, higher droplet jumping probability, slower droplet growth rate and lower surface coverage due to the more structured hierarchical structures.

Designing magnetic droplet soliton nucleation employing spin polarizer

NASA Astrophysics Data System (ADS)

Mohseni, Morteza; Mohseni, Majid

2018-04-01

We show by means of micromagnetic simulations that spin polarizer in nano-contact (NC) spin torque oscillators as the representative of the fixed layer in an orthogonal pseudo-spin valve can be employed to design and to control magnetic droplet soliton nucleation and dynamics. We found that using a tilted spin polarizer layer decreases the droplet nucleation time which is more suitable for high speed applications. However, a tilted spin polarizer increases the nucleation current and decreases the frequency stability of the droplet. Additionally, by driving the magnetization inhomogenously at the NC region, it is found that a tilted spin polarizer reduces the precession angle of the droplet and through an interplay with the Oersted field of the DC current, it breaks the spatial symmetry of the droplet profile. Our findings explore fundamental insight into nano-scale magnetic droplet soliton dynamics with potential tunability parameters for future microwave electronics.

Dynamic and spectroscopic studies of nano-micelles comprising dye in water/ dioctyl sodium sulfosuccinate /decane droplet microemulsion at constant water content

NASA Astrophysics Data System (ADS)

Rahdar, Abbas; Almasi-Kashi, Mohammad

2017-01-01

In the present work, the dynamic and spectroscopic properties of water-in-decane dioctyl sodium sulfosuccinate (AOT) microemulsions comprising dye, Rhodamine B (RB), were studied by varying content of decane at the constant water content (W = 20), by using dynamic light scattering (DLS), UV/visible, and fluorescence techniques. The characterization results of DLS of AOT micelles showed that by decreasing concentration of Rhodamine B in the water/AOT/decane microemulsion, the inter-droplet interactions changed from attractive to repulsive as the mass fraction of nano-droplets (MFD) increased. A deviation in the absorption spectra of Rhodamine B from the Beer's law at the high Rhodamine B concentration (0.001) was observed in the AOT reversed micelles. The Quenching in the emission intensity of AOT droplets comprising Rhodamine B and red shift in λmax of fluorescence of dye was observed as a function of concentration of RB in AOT RMs. The Stokes shift of AOT droplets containing the high concentration of RB, increased with mass fraction of nano-droplet (MFD), whereas at the low Rhodamine B concentration, its variation remained constant up to MFD = 0.07, and then increased.

Live single cell functional phenotyping in droplet nano-liter reactors

NASA Astrophysics Data System (ADS)

Konry, Tania; Golberg, Alexander; Yarmush, Martin

2013-11-01

While single cell heterogeneity is present in all biological systems, most studies cannot address it due to technical limitations. Here we describe a nano-liter droplet microfluidic-based approach for stimulation and monitoring of surfaceand secreted markers of live single immune dendritic cells (DCs) as well as monitoring the live T cell/DC interaction. This nano-liter in vivo simulating microenvironment allows delivering various stimuli reagents to each cell and appropriate gas exchanges which are necessary to ensure functionality and viability of encapsulated cells. Labeling bioassay and microsphere sensors were integrated into nano-liter reaction volume of the droplet to monitor live single cell surface markers and secretion analysis in the time-dependent fashion. Thus live cell stimulation, secretion and surface monitoring can be obtained simultaneously in distinct microenvironment, which previously was possible using complicated and multi-step in vitro and in vivo live-cell microscopy, together with immunological studies of the outcome secretion of cellular function.

Loss of superhydrophobicity of hydrophobic micro/nano structures during condensation.

PubMed

Jo, HangJin; Hwang, Kyung Won; Kim, DongHyun; Kiyofumi, Moriyama; Park, Hyun Sun; Kim, Moo Hwan; Ahn, Ho Seon

2015-04-23

Condensed liquid behavior on hydrophobic micro/nano-structured surfaces is a subject with multiple practical applications, but remains poorly understood. In particular, the loss of superhydrophobicity of hydrophobic micro/nanostructures during condensation, even when the same surface shows water-repellant characteristics when exposed to air, requires intensive investigation to improve and apply our understanding of the fundamental physics of condensation. Here, we postulate the criterion required for condensation to form from inside the surface structures by examining the grand potentials of a condensation system, including the properties of the condensed liquid and the conditions required for condensation. The results imply that the same hydrophobic micro/nano-structured surface could exhibit different liquid droplet behavior depending on the conditions. Our findings are supported by the observed phenomena: the initiation of a condensed droplet from inside a hydrophobic cavity, the apparent wetted state changes, and the presence of sticky condensed droplets on the hydrophobic micro/nano-structured surface.

Crystal Nucleation and Crystal Growth and Mass Transfer in Internally Mixed Sucrose/NaNO3 Particles.

PubMed

Ji, Zhi-Ru; Zhang, Yun; Pang, Shu-Feng; Zhang, Yun-Hong

2017-10-19

Secondary organic aerosols (SOA) can exist in a glassy or semisolid state under low relative humidity (RH) conditions, in which the particles show nonequilibrium kinetic characteristics with changing ambient RH. Here, we selected internally mixed sucrose/NaNO 3 droplets with organic to inorganic molar ratios (OIRs) of 1:8, 1:4, 1:2, and 1:1 as a proxy for multicomponent ambient aerosols to study crystal nucleation and growth processes and water transport under a highly viscous state with the combination of an RH-controlling system and a vacuum Fourier transform infrared (FTIR) spectrometer. The initial efflorescence RH (ERH) of NaNO 3 decreased from ∼45% for pure NaNO 3 droplets to ∼38.6 and ∼37.9% for the 1:8 and 1:4 sucrose/NaNO 3 droplets, respectively, while no crystallization of NaNO 3 occurred for the 1:2 and 1:1 droplets in the whole RH range. Thus, the addition of sucrose delayed the ERH and even completely inhibited nucleation of NaNO 3 in the mixed droplets. In addition, the crystal growth of NaNO 3 was suppressed in the 1:4 and 1:8 droplets most likely due to the slow diffusion of Na + and NO 3 - ions at low RH. Water uptake/release of sucrose/NaNO 3 particles quickly arrived at equilibrium at high RH, while the hygroscopic process was kinetically controlled under low RH. The half-time ratio between the liquid water content and the RH was used to describe the mass transfer behavior. For the 1:1 droplets, no mass limitation was observed with the ratio approaching to 1 when the RH was higher than 53%. The ratio increased 1 order of magnitude under an ultraviscous state with RH ranging from 53 to 15% and increased a further 1 order of magnitude at RH < 15% under a glassy state.

Nano Liquid Crystal Droplet Impact on Solid Surfaces

NASA Astrophysics Data System (ADS)

Zhang, Rui; de Pablo, Juan; dePablo Team

2015-03-01

Liquid droplet impaction on solid surfaces is an important problem with a wide range of applications in everyday life. Liquid crystals (LCs) are anisotropic liquids whose internal structure gives rise to rich optical and morphological phenomena. In this work we study the liquid crystal droplet impaction on solid surfaces by molecular dynamics simulations. We employ a widely used Gay-Berne model to describe the elongated liquid crystal molecules and their interactions. Our work shows that, in contrast to isotropic liquids, drop deformation is symmetric unless an instability kicks in, in which case a nano scale liquid crystal droplet exhibits distinct anisotropic spreading modes that do not occur in simple liquids. The drop prefers spreading along the low viscosity direction, but inertia can in some cases overcome that bias. The effects of the director field of the droplet, preferred anchoring direction and the anchoring strength of the wall are investigated. Large scale (0.1 micron) simulations are performed to connect our nano scale results to the experiments. Our studies indicate that LCs could provide an interesting alternative for development of next-generation printing inks.

Exploring Chondrule and CAI Rims Using Micro- and Nano-Scale Petrological and Compositional Analysis

NASA Astrophysics Data System (ADS)

Cartwright, J. A.; Perez-Huerta, A.; Leitner, J.; Vollmer, C.

2017-12-01

As the major components within chondrites, chondrules (mm-sized droplets of quenched silicate melt) and calcium-aluminum-rich inclusions (CAI, refractory) represent the most abundant and the earliest materials that solidified from the solar nebula. However, the exact formation mechanisms of these clasts, and whether these processes are related, remains unconstrained, despite extensive petrological and compositional study. By taking advantage of recent advances in nano-scale tomographical techniques, we have undertaken a combined micro- and nano-scale study of CAI and chondrule rim morphologies, to investigate their formation mechanisms. The target lithologies for this research are Wark-Lovering rims (WLR), and fine-grained rims (FGR) around CAIs and chondrules respectively, present within many chondrites. The FGRs, which are up to 100 µm thick, are of particular interest as recent studies have identified presolar grains within them. These grains predate the formation of our Solar System, suggesting FGR formation under nebular conditions. By contrast, WLRs are 10-20 µm thick, made of different compositional layers, and likely formed by flash-heating shortly after CAI formation, thus recording nebular conditions. A detailed multi-scale study of these respective rims will enable us to better understand their formation histories and determine the potential for commonality between these two phases, despite reports of an observed formation age difference of up to 2-3 Myr. We are using a combination of complimentary techniques on our selected target areas: 1) Micro-scale characterization using standard microscopic and compositional techniques (SEM-EBSD, EMPA); 2) Nano-scale characterization of structures using transmission electron microscopy (TEM) and elemental, isotopic and tomographic analysis with NanoSIMS and atom probe tomography (APT). Preliminary nano-scale APT analysis of FGR morphologies within the Allende carbonaceous chondrite has successfully discerned complex chondritic mineralogies and compositional differences across boundaries, which is one of the first applications of in-situ APT techniques to chondrites. Further data reduction will allow us to characterize the exact phases present, and further chondrite analyses are in progress.

Reverse micelle-loaded lipid nano-emulsions: new technology for nano-encapsulation of hydrophilic materials.

PubMed

Anton, Nicolas; Mojzisova, Halina; Porcher, Emilien; Benoit, Jean-Pierre; Saulnier, Patrick

2010-10-15

This study presents novel, recently patented technology for encapsulating hydrophilic species in lipid nano-emulsions. The method is based on the phase-inversion temperature method (the so-called PIT method), which follows a low-energy and solvent-free process. The nano-emulsions formed are stable for months, and exhibit droplet sizes ranging from 10 to 200 nm. Hydrophilic model molecules of fluorescein sodium salt are encapsulated in the oily core of these nano-emulsion droplets through their solubilisation in the reverse micellar system. As a result, original, multi-scaled nano-objects are generated with a 'hydrophilic molecule in a reverse-micelles-in-oil-in-water' structure. Once fluorescein has been encapsulated it remains stable, for thermodynamic reasons, and the encapsulation yields can reach 90%. The reason why such complex objects can be formed is due to the soft method used (PIT method) which allows the conservation of the structure of the reverse micelles throughout the formulation process, up to their entrapment in the nano-emulsion droplets. In this study, we focus the investigation on the process itself, revealing its potential and limits. Since the formulation of nanocarriers for the encapsulation of hydrophilic substances still remains a challenge, this study may constitute a significant advance in this field. Copyright 2010 Elsevier B.V. All rights reserved.

Explosion of Leidenfrost Droplets

NASA Astrophysics Data System (ADS)

Moreau, Florian; Colinet, Pierre; Dorbolo, Stephane

2012-11-01

When a drop is released on a plate heated above a given temperature, a thin layer of vapour can isolate the droplet so that it levitates over the plate. This effect was first reported by Leidenfrost in 1756. However, this fascinating subject remains an active field of research in both fundamental and applied researches. In this work, we focus on what happens when surfactant is added to the drop. The aim is to study the influence of a decrease of the surface tension. Surprisingly, as the droplet evaporates, suddenly it explodes. The evolution of the droplet and the resulting explosion are followed using a high speed camera. We show that when a critical concentration of surfactant is reached inside the drop, a shell of surfactant is formed leading to the explosion. The authors would like to thank FNRS for financial support. This work is financially supported by ODILE project (Contract No. FRFC 2.4623.11).

On-chip dilution in nanoliter droplets.

PubMed

Thakur, Raviraj; Amin, Ahmed M; Wereley, Steve

2015-09-07

Droplet microfluidics is enabling reactions at nano- and picoliter scale, resulting in faster and cheaper biological and chemical analyses. However, varying concentrations of samples on a drop-to-drop basis is still a challenging task in droplet microfluidics, primarily limited due to lack of control over individual droplets. In this paper, we report an on-chip microfluidic droplet dilution strategy using three-valve peristaltic pumps.

Advances and patents about grinding equipments with nano-particle jet minimum quantity lubrication.

PubMed

Jia, Dongzhou; Li, Changhe; Wang, Sheng; Zhang, Qiang; Hou, Yali

2014-01-01

In recent years, a large number of patents have been devoted to developing minimum quantity lubrication (MQL) grinding techniques that can significantly improve both environmentally conscious and energy saving and costeffective sustainable grinding fluid alternatives. Among them, one patent is about a controllable nano-fluids jet MQL grinding system based on electrostatic atomization. Using the principle of electrostatics, it can achieve the control of droplet transfer by charging the sprayed droplets. This system can improve the uniformity of the droplet spectrum, liquid deposition efficiency and effective utilization of liquid. It can also effectively control the movement patterns of the droplets, thereby reducing the pollution of the environment and providing better health protection for workers. Although researchers accomplished profound and systematic studies on MQL, especially on nano-particles jet MQL. It can solve the shortage of MQL in cooling performance, greatly improve the working environment, save energy and reduce costs to achieve a low-carbon manufacturing. The unique lubricating performance and tribological property of solid nano-particles form nano-particle shearing films at the grinding wheel/workpiece interface, which can enhance the lubricating performance of MQL grinding. Existing studies on MQL grinding equipments, however, cannot meet the needs of the technological development. Therefore, our research provided a general introduction of the latest patients and research progress of nanoparticles jet MQL grinding equipments presented by the research team from Qingdao Technological University.

Live single cell functional phenotyping in droplet nano-liter reactors.

PubMed

Konry, Tania; Golberg, Alexander; Yarmush, Martin

2013-11-11

While single cell heterogeneity is present in all biological systems, most studies cannot address it due to technical limitations. Here we describe a nano-liter droplet microfluidic-based approach for stimulation and monitoring of surface and secreted markers of live single immune dendritic cells (DCs) as well as monitoring the live T cell/DC interaction. This nano-liter in vivo simulating microenvironment allows delivering various stimuli reagents to each cell and appropriate gas exchanges which are necessary to ensure functionality and viability of encapsulated cells. Labeling bioassay and microsphere sensors were integrated into nano-liter reaction volume of the droplet to monitor live single cell surface markers and secretion analysis in the time-dependent fashion. Thus live cell stimulation, secretion and surface monitoring can be obtained simultaneously in distinct microenvironment, which previously was possible using complicated and multi-step in vitro and in vivo live-cell microscopy, together with immunological studies of the outcome secretion of cellular function.

Multilevel and Latent Variable Modeling with Composite Links and Exploded Likelihoods

ERIC Educational Resources Information Center

Rabe-Hesketh, Sophia; Skrondal, Anders

2007-01-01

Composite links and exploded likelihoods are powerful yet simple tools for specifying a wide range of latent variable models. Applications considered include survival or duration models, models for rankings, small area estimation with census information, models for ordinal responses, item response models with guessing, randomized response models,…

Coalescence-induced jumping of nanoscale droplets on super-hydrophobic surfaces

NASA Astrophysics Data System (ADS)

Liang, Zhi; Keblinski, Pawel; Nanoscale Science; Engineering Center Team

The coalescence-induced jumping of tens of microns size droplets on super-hydrophobic surfaces has been observed in both experiments and simulations. However, whether the coalescence-induced jumping would occur for smaller, particularly nanoscale droplets, is an open question. Using molecular dynamics simulations, we demonstrate that in spite of the large internal viscous dissipation, coalescence of two nanoscale droplets on a super-hydrophobic surface can result in a jumping of the coalesced droplet from the surface with a speed of a few m/s. Similar to the coalescence-induced jumping of microscale droplets, we observe that the bridge between the coalescing nano-droplets expands and impacts the solid surface, which leads to an acceleration of the coalesced droplet by the pressure force from the solid surface. We observe that the jumping velocity decreases with the droplet size and its ratio to the inertial-capillary velocity is a constant of about 0.126, which is close to the minimum value of 0.111 predicted by continuum-level modeling of Enright et al. [R. Enright, N. Miljkovic, J. Sprittles, K. Nolan, R. Mitchell, and E. N. Wang, ACS Nano 8, 10352 (2014)].

Development of method of optimized flavor production systems design based on nano-emulsification Kawista (Feronia limonia) Fruit extraction

NASA Astrophysics Data System (ADS)

Suyanto, A.; Noor, E.; Fahma, F.; Rusli, M. S.; Djatna, T.

2018-01-01

‘Kawista’ (Feronia limonia) as a tropical fruit has unique flavor that can be applied as a flavor for food products. Flavor as volatile components are unstable by environment factors such as temperature and storage. Flavor nano emulsification form to improve the stability towards environment and increase its use in food products. Research carried out is system development of the nano emulsification Kawista extract flavor with sonication method. The best treatments are selected by Response Surface Methodology (RSM) for independent variable are amplitude (70-100%), time (90-150s) and temperature (5-45°C) controlled by the software of the device. The Flavor Extraction by maceration technique extended highest yield and flavor components. Nano-emulsions made with composition 1% (w/w) flavor extract, 2% (w/w) surfactant (tween 80), 0.25% Gum, and 96.75% (w/w) deionized water. The probe of sonication successfully for preparing stable O/W nano emulsions at amplitude, time and temperature 81.01%, 150s, 45°C, respectively. Characteristic of nano-emulsions i.e energy input (15.489J), viscosity (2.076 mPa.s), droplet size (13.446nm), and Polydispersity index (0.469).

Secondary atomization in the combustion of electrostatic sprays

NASA Technical Reports Server (NTRS)

Gomez, Alessandro; Chen, Gung

1993-01-01

The combustion of electrosprays in a laminar counterflow diffusion flame has been experimentally studied by measuring droplet size and velocity distributions and gas-phase temperature. Detailed examination of the evolution of droplet size distribution as droplets approach the flame shows that, if substantial evaporation occurs before droplets 'interact' with the flame, the size distribution becomes bimodal. A secondary, sharp peak, in fact, develops in correspondence of diameters about one order of magnitude smaller than the mean. No evaporation mechanism can account for the development of such bimodality, that can be explained only in terms of a disintegration of droplets into finer fragments of size much smaller than the parent ones. This fission is of electric nature and it occurs when the repulsion of electric charges overcomes the surface tension cohesive force ultimately leading to a disintegration into finer fragments at or about the so-called Rayleigh limit. We here report on the first observation in combustion environments of such 'explosions'. If, on the other hand, droplets enter the very high temperature region before exploding, there appears to be no evidence of bimodality in their size distribution. In this case, in fact, flame chemi-ions may neutralize the charge on the droplets and thus prevent disruption.

Self-organization of quantum-dot pairs by high-temperature droplet epitaxy

PubMed Central

Holmes, Kyland; Mazur, Yuriy I; Ramsey, Kimberly A; Salamo, Gregory J

2006-01-01

The spontaneously formation of epitaxial GaAs quantum-dot pairs was demonstrated on an AlGaAs surface using Ga droplets as a Ga nano-source. The dot pair formation was attributed to the anisotropy of surface diffusion during high-temperature droplet epitaxy.

Combustion diagnosis for analysis of solid propellant rocket abort hazards: Role of spectroscopy

NASA Astrophysics Data System (ADS)

Gill, W.; Cruz-Cabrera, A. A.; Donaldson, A. B.; Lim, J.; Sivathanu, Y.; Bystrom, E.; Haug, A.; Sharp, L.; Surmick, D. M.

2014-11-01

Solid rocket propellant plume temperatures have been measured using spectroscopic methods as part of an ongoing effort to specify the thermal-chemical-physical environment in and around a burning fragment of an exploded solid rocket at atmospheric pressures. Such specification is needed for launch safety studies where hazardous payloads become involved with large fragments of burning propellant. The propellant burns in an off-design condition producing a hot gas flame loaded with burning metal droplets. Each component of the flame (soot, droplets and gas) has a characteristic temperature, and it is only through the use of spectroscopy that their temperature can be independently identified.

Flow-induced voltage generation by moving a nano-sized ionic liquids droplet over a graphene sheet: Molecular dynamics simulation.

PubMed

Shao, Qunfeng; Jia, Jingjing; Guan, Yongji; He, Xiaodong; Zhang, Xiaoping

2016-03-28

In this work, the phenomenon of the voltage generation is explored by using the molecular dynamics simulations, which is performed by driving a nano-sized droplet of room temperature ionic liquids moving along the monolayer graphene sheet for the first time. The studies show that the cations and anions of the droplet will move with velocity nonlinearly increasing to saturation arising by the force balance. The traditional equation for calculating the induced voltage is developed by taking the charge density into consideration, and larger induced voltages in μV-scale are obtained from the nano-size simulation systems based on the ionic liquids (ILs) for its enhanced ionic drifting velocities. It is also derived that the viscosity acts as a reduction for the induced voltage by comparing systems composed of two types of ILs with different viscosity and temperature.

Deposition pattern and tracer particle motion of evaporating multi-component sessile droplets.

PubMed

Amjad, Muhammad; Yang, Yang; Raza, Ghulam; Gao, Hui; Zhang, Jun; Zhou, Leping; Du, Xiaoze; Wen, Dongsheng

2017-11-15

The understanding of near-wall motion, evaporation behavior and dry pattern of sessile nanofluid droplets is fundamental to a wide range of applications such as painting, spray drying, thin film coating, fuel injection and inkjet printing. However, a deep insight into the heat transfer, fluid flow, near-wall particle velocity and their effects on the resulting dry patterns is still much needed to take the full advantage of these nano-sized particles in the droplet. This work investigates the effect of direct absorptive silicon/silver (Si/Ag) hybrid nanofluids via two experiments. The first experiment identifies the motion of tracer particles near the triple line of a sessile nanofluid droplet on a super-hydrophilic substrate under ambient conditions by the multilayer nanoparticle image velocimetry (MnPIV) technique. The second experiment reveals the effect of light-sensitive Si/Ag composite nanoparticles on the droplet evaporation rate and subsequent drying patterns under different radiation intensities. The results show that the presence of nanoparticle in a very small proportion significantly affects the motion of tracer particles, leading to different drying patterns and evaporation rates, which can be very important for the applications such as spray coating and inkjet printing. Copyright © 2017 Elsevier Inc. All rights reserved.

Controlled and tunable polymer particles' production using a single microfluidic device

NASA Astrophysics Data System (ADS)

Amoyav, Benzion; Benny, Ofra

2018-04-01

Microfluidics technology offers a new platform to control liquids under flow in small volumes. The advantage of using small-scale reactions for droplet generation along with the capacity to control the preparation parameters, making microfluidic chips an attractive technology for optimizing encapsulation formulations. However, one of the drawback in this methodology is the ability to obtain a wide range of droplet sizes, from sub-micron to microns using a single chip design. In fact, typically, droplet chips are used for micron-dimension particles, while nanoparticles' synthesis requires complex chips design (i.e., microreactors and staggered herringbone micromixer). Here, we introduce the development of a highly tunable and controlled encapsulation technique, using two polymer compositions, for generating particles ranging from microns to nano-size using the same simple single microfluidic chip design. Poly(lactic-co-glycolic acid) (PLGA 50:50) or PLGA/polyethylene glycol polymeric particles were prepared with focused-flow chip, yielding monodisperse particle batches. We show that by varying flow rate, solvent, surfactant and polymer composition, we were able to optimize particles' size and decrease polydispersity index, using simple chip designs with no further related adjustments or costs. Utilizing this platform, which offers tight tuning of particle properties, could offer an important tool for formulation development and can potentially pave the way towards a better precision nanomedicine.

Counterion-enhanced cyanine dye loading into lipid nano-droplets for single-particle tracking in zebrafish.

PubMed

Kilin, Vasyl N; Anton, Halina; Anton, Nicolas; Steed, Emily; Vermot, Julien; Vandamme, Thierry F; Mely, Yves; Klymchenko, Andrey S

2014-06-01

Superior brightness of fluorescent nanoparticles places them far ahead of the classical fluorescent dyes in the field of biological imaging. However, for in vivo applications, inorganic nanoparticles, such as quantum dots, are limited due to the lack of biodegradability. Nano-emulsions encapsulating high concentrations of organic dyes are an attractive alternative, but classical fluorescent dyes are inconvenient due to their poor solubility in the oil and their tendency to form non-fluorescent aggregates. This problem was solved here for a cationic cyanine dye (DiI) by substituting its perchlorate counterion for a bulky and hydrophobic tetraphenylborate. This new dye salt, due to its exceptional oil solubility, could be loaded at 8 wt% concentration into nano-droplets of controlled size in the range 30-90 nm. Our 90 nm droplets, which contained >10,000 cyanine molecules, were >100-fold brighter than quantum dots. This extreme brightness allowed, for the first time, single-particle tracking in the blood flow of live zebrafish embryo, revealing both the slow and fast phases of the cardiac cycle. These nano-droplets showed minimal cytotoxicity in cell culture and in the zebrafish embryo. The concept of counterion-based dye loading provides a new effective route to ultra-bright lipid nanoparticles, which enables tracking single particles in live animals, a new dimension of in vivo imaging. Copyright © 2014 Elsevier Ltd. All rights reserved.

Physical properties of a frozen yogurt fortified with a nano-emulsion containing purple rice bran oil

USDA-ARS?s Scientific Manuscript database

The objectives of this study were to develop and evaluate a frozen yogurt (FY) fortified with a nano-emulsion containing purple rice bran oil (NPRBO). A nano-emulsion with a droplet size range of 150-300 nm was produced by sonication followed by ultra-shear homogenization. The nano-emulsion was mi...

Conductivity of laser printed copper structures limited by nano-crystal grain size and amorphous metal droplet shell

NASA Astrophysics Data System (ADS)

Winter, Shoshana; Zenou, Michael; Kotler, Zvi

2016-04-01

We present a study of the morphology and electrical properties of copper structures which are printed by laser induced forward transfer from bulk copper. The percentage of voids and the oxidation levels are too low to account for the high resistivities (~4 to 14 times the resistivity of bulk monocrystalline copper) of these structures. Transmission electron microscope (TEM) images of slices cut from the printed areas using a focused ion beam (FIB) show nano-sized crystal structures with grain sizes that are smaller than the electron free path length. Scattering from such grain boundaries causes a significant increase in the resistivity and can explain the measured resistivities of the structures. The TEM images also show a nano-amorphous layer (~5 nm) at the droplet boundaries which also contributes to the overall resistivity. Such morphological characteristics are best explained by the ultrafast cooling rate of the molten copper droplets during printing.

From Initial Nucleation to Cassie-Baxter State of Condensed Droplets on Nanotextured Superhydrophobic Surfaces.

PubMed

Lv, Cunjing; Zhang, Xiwen; Niu, Fenglei; He, Feng; Hao, Pengfei

2017-02-16

Understanding how droplet condensation happens plays an essential role for our fundamental insights of wetting behaviors in nature and numerous applications. Since there is a lack of study of the initial formation and growing processes of condensed droplets down to nano-/submicroscale, relevant underlying mechanisms remain to be explored. We report an in situ observation of vapor condensation on nano-/microtextured superhydrophobic surfaces using optical microscopy. An interesting picture of the vapor condensation, from the initial appearance of individual small droplets (≤1 μm) to a Cassie-Baxter wetting state (>30 μm), are exhibited. It is found that individual droplets preferentially nucleate at the top and the edge of single micropillars with very high apparent contact angles on the nanotextures. Scenarios of two distinguished growing modes are reported statistically and the underlying mechanisms are discussed in the view of thermodynamics. We particularly reveal that the formation of the Cassie-Baxter wetting state is a result of a continuous coalescence of individual small droplets, in which the nanotexture-enhanced superhydrophobicity plays a crucial role. We envision that these fundamental findings can deepen our understanding of the nucleation and development of condensed droplets in nanoscale, so as to optimize design strategies of superhydrophobic materials for a broad range of water-harvesting and heat-transfer systems.

From Initial Nucleation to Cassie-Baxter State of Condensed Droplets on Nanotextured Superhydrophobic Surfaces

NASA Astrophysics Data System (ADS)

Lv, Cunjing; Zhang, Xiwen; Niu, Fenglei; He, Feng; Hao, Pengfei

2017-02-01

Understanding how droplet condensation happens plays an essential role for our fundamental insights of wetting behaviors in nature and numerous applications. Since there is a lack of study of the initial formation and growing processes of condensed droplets down to nano-/submicroscale, relevant underlying mechanisms remain to be explored. We report an in situ observation of vapor condensation on nano-/microtextured superhydrophobic surfaces using optical microscopy. An interesting picture of the vapor condensation, from the initial appearance of individual small droplets (≤1 μm) to a Cassie-Baxter wetting state (>30 μm), are exhibited. It is found that individual droplets preferentially nucleate at the top and the edge of single micropillars with very high apparent contact angles on the nanotextures. Scenarios of two distinguished growing modes are reported statistically and the underlying mechanisms are discussed in the view of thermodynamics. We particularly reveal that the formation of the Cassie-Baxter wetting state is a result of a continuous coalescence of individual small droplets, in which the nanotexture-enhanced superhydrophobicity plays a crucial role. We envision that these fundamental findings can deepen our understanding of the nucleation and development of condensed droplets in nanoscale, so as to optimize design strategies of superhydrophobic materials for a broad range of water-harvesting and heat-transfer systems.

Statistical effects related to low numbers of reacting molecules analyzed for a reversible association reaction A + B = C in ideally dispersed systems: An apparent violation of the law of mass action

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

Szymanski, R., E-mail: rszymans@cbmm.lodz.pl; Sosnowski, S.; Maślanka, Ł.

2016-03-28

Theoretical analysis and computer simulations (Monte Carlo and numerical integration of differential equations) show that the statistical effect of a small number of reacting molecules depends on a way the molecules are distributed among the small volume nano-reactors (droplets in this study). A simple reversible association A + B = C was chosen as a model reaction, enabling to observe both thermodynamic (apparent equilibrium constant) and kinetic effects of a small number of reactant molecules. When substrates are distributed uniformly among droplets, all containing the same equal number of substrate molecules, the apparent equilibrium constant of the association is highermore » than the chemical one (observed in a macroscopic—large volume system). The average rate of the association, being initially independent of the numbers of molecules, becomes (at higher conversions) higher than that in a macroscopic system: the lower the number of substrate molecules in a droplet, the higher is the rate. This results in the correspondingly higher apparent equilibrium constant. A quite opposite behavior is observed when reactant molecules are distributed randomly among droplets: the apparent association rate and equilibrium constants are lower than those observed in large volume systems, being the lower, the lower is the average number of reacting molecules in a droplet. The random distribution of reactant molecules corresponds to ideal (equal sizes of droplets) dispersing of a reaction mixture. Our simulations have shown that when the equilibrated large volume system is dispersed, the resulting droplet system is already at equilibrium and no changes of proportions of droplets differing in reactant compositions can be observed upon prolongation of the reaction time.« less

Moisture condensation behavior of hierarchically carbon nanotube-grafted carbon nanofibers.

PubMed

Park, Kyu-Min; Lee, Byoung-Sun; Youk, Ji Ho; Lee, Jinyong; Yu, Woong-Reol

2013-11-13

Hierarchical micro/nanosurfaces with nanoscale roughness on microscale uneven substrates have been the subject of much recent research interest because of phenomena such as superhydrophobicity. However, an understanding of the effect of the difference in the scale of the hierarchical entities, i.e., nanoscale roughness on microscale uneven substrates as opposed to nanoscale roughness on (a larger) nanoscale uneven surface, is still lacking. In this study, we investigated the effect of the difference in scale between the nano- and microscale features. We fabricated carbon nanotube-grafted carbon nanofibers (CNFs) by dispersing a catalyst precursor in poly (acrylonitrile) (PAN) solution, electrospinning the PAN/catalyst precursor solution, carbonization of electrospun PAN nanofibers, and direct growth of carbon nanotubes (CNTs) on the CNFs. We investigated the relationships between the catalyst concentrations, the size of catalyst nanoparticles on CNFs, and the sizes of CNFs and CNTs. Interestingly, the hydrophobic behavior of micro/nano and nano/nano hierarchical surfaces with water droplets was similar; however a significant difference in the water condensation behavior was observed. Water condensed into smaller droplets on the nano/nano hierarchical surface, causing it to dry much faster.

Preparation and characterization of a new lipid nano-emulsion containing two cosurfactants, sodium palmitate for droplet size reduction and sucrose palmitate for stability enhancement.

PubMed

Takegami, Shigehiko; Kitamura, Keisuke; Kawada, Hiroto; Matsumoto, Yu; Kitade, Tatsuya; Ishida, Hiroharu; Nagata, Chieyo

2008-08-01

A new lipid nano-emulsion (LNE) was prepared from soybean oil and phosphatidylcholine (PC) employing two cosurfactants, sodium palmitate (PA) for reduced droplet size and sucrose palmitate (SP) for stability enhancement. The mean droplet size of LNEs prepared at a PA/PC (w/w) ratio of larger than 1/10 was found to be ca. 50 nm by dynamic light scattering and atomic force microscopy. However, during the 12-month storage, the PA/PC (1/10)-LNE showed an increase in mean droplet size and broadening of the droplet size distribution due to coalescence of the LNE particles. In a saline solution, the coalescence proceeded very rapidly, i.e., the mean droplet size increased to more than 150 nm within 0.5 h. To suppress the coalescence of LNE particles, four sucrose fatty acid esters of different chain lengths were examined as candidate cosurfactants. The results showed that PA/SP/PC (1/4/10)-LNE could maintain a mean droplet size around 50 nm for 12 months. In a saline solution, the mean droplet size could be maintained within 100 nm even after 24 h. Slight formation of flocculation in the LNEs depending on the storage period was suggested by measurement of the 31P nuclear magnetic resonance line width of the LNEs.

Traversing the Skin Barrier with Nano-emulsions.

PubMed

Burger, Cornel; Shahzad, Yasser; Brummer, Alicia; Gerber, Minja; du Plessis, Jeanetta

2017-01-01

In recent years, colloidal delivery systems based on nano-emulsion are gaining popularity; being used for encapsulation and delivery of many drugs. This review therefore aims at summarizing various methods of nano-emulsion formulation and their use as a topical and transdermal delivery vehicle for a number of active pharmaceutical ingredients from different pharmacological classes. This article represents a systematic review of nano-emulsions for topical and transdermal drug delivery. A vast literature was searched and critically analysed. Nano-emulsions are thermokinetically stable dispersion systems, which have been used in topical and transdermal delivery of a number of pharmaceutically active compounds. Nano-emulsions have a narrow droplet size range with tuneable surface properties, which make them an ideal delivery vehicle. Nanoemulsions have a number of advantages over conventional emulsions, including easy preparation using various low and high energy methods, optical transparency, high solubilisation capacity, high stability to droplet aggregation and the ability to penetrate the skin; thus allowing the transdermal delivery of drugs. This review indicated that nano-emulsions are promising vehicle for entrapping various drugs and are suitable for traversing the skin barrier for systemic effects. Copyright© Bentham Science Publishers; For any queries, please email at epub@benthamscience.org.

Merging magnetic droplets by a magnetic field pulse

NASA Astrophysics Data System (ADS)

Wang, Chengjie; Xiao, Dun; Liu, Yaowen

2018-05-01

Reliable manipulation of magnetic droplets is of immense importance for their applications in spin torque oscillators. Using micromagnetic simulations, we find that the antiphase precession state, which originates in the dynamic dipolar interaction effect, is a favorable stable state for two magnetic droplets nucleated at two identical nano-contacts. A magnetic field pulse can be used to destroy their stability and merge them into a big droplet. The merging process strongly depends on the pulse width as well as the pulse strength.

Acoustic droplet vaporization of vascular droplets in gas embolotherapy

NASA Astrophysics Data System (ADS)

Bull, Joseph

2016-11-01

This work is primarily motivated by a developmental gas embolotherapy technique for cancer treatment. In this methodology, infarction of tumors is induced by selectively formed vascular gas bubbles that arise from the acoustic vaporization of vascular droplets. Additionally, micro- or nano-droplets may be used as vehicles for localized drug delivery, with or without flow occlusion. In this talk, we examine the dynamics of acoustic droplet vaporization through experiments and theoretical/computational fluid mechanics models, and investigate the bioeffects of acoustic droplet vaporization on endothelial cells and in vivo. Functionalized droplets that are targeted to tumor vasculature are examined. The influence of fluid mechanical and acoustic parameters, as well as droplet functionalization, is explored. This work was supported by NIH Grant R01EB006476.

Insights into Aqueous-phase processing through Comparison of the Organic Chemical Composition of Atmospheric Particles and Cloud Water in the Southeast United States

NASA Astrophysics Data System (ADS)

Boone, E.; Laskin, J.; Laskin, A.; Wirth, C.; Shepson, P. B.; Stirm, B. H.; Pratt, K.

2014-12-01

Organic compounds comprise a significant mass fraction of submicron atmospheric particles with considerable contribution from secondary organic aerosol (SOA), a large fraction of which is formed from the oxidation of biogenic volatile organic compounds. Aqueous-phase reactions in particles and cloud droplets are suggested to increase SOA mass and change the chemical composition the particles following cloud evaporation. Aqueous-phase processing may also explain discrepancies between measurements and models. To gain a better understanding of these processes, cloud water and below-cloud atmospheric particles were collected onboard a research aircraft during the Southeast Oxidants and Aerosol Study (SOAS) over Alabama in June 2013. Nanospray desorption electrospray ionization (nano-DESI) and direct electrospray ionization (ESI) coupled with high resolution mass spectrometry were utilized to compare the organic molecular composition of the particle and cloud water samples, respectively. Several hundred unique compounds have been identified in the particle and cloud water samples, allowing possible aqueous-phase reactions to be examined. Hydrolysis of organosulfate compounds, aqueous-phase formation of nitrogen-containing compounds, and possible fragmentation of oligomeric compounds will be discussed, with comparisons to previous laboratory studies. This study provides insights into aqueous-phase reactions in ambient cloud droplets.

Nano-LC/MALDI-MS using a column-integrated spotting probe for analysis of complex biomolecule samples.

PubMed

Hioki, Yusaku; Tanimura, Ritsuko; Iwamoto, Shinichi; Tanaka, Koichi

2014-03-04

Nanoflow liquid chromatography (nano-LC) is an essential technique for highly sensitive analysis of complex biological samples, and matrix-assisted laser desorption/ionization mass spectrometry (MALDI-MS) is advantageous for rapid identification of proteins and in-depth analysis of post-translational modifications (PTMs). A combination of nano-LC and MALDI-MS (nano-LC/MALDI-MS) is useful for highly sensitive and detailed analysis in life sciences. However, the existing system does not fully utilize the advantages of each technique, especially in the interface of eluate transfer from nano-LC to a MALDI plate. To effectively combine nano-LC with MALDI-MS, we integrated a nano-LC column and a deposition probe for the first time (column probe) and incorporated it into a nano-LC/MALDI-MS system. Spotting nanoliter eluate droplets directly from the column onto the MALDI plate prevents postcolumn diffusion and preserves the chromatographic resolution. A DHB prespotted plate was prepared to suit the fabricated column probe to concentrate the droplets of nano-LC eluate. The performance of the advanced nano-LC/MALDI-MS system was substantiated by analyzing protein digests. When the system was coupled with multidimensional liquid chromatography (MDLC), trace amounts of glycopeptides that spiked into complex samples were successfully detected. Thus, a nano-LC/MALDI-MS direct-spotting system that eliminates postcolumn diffusion was constructed, and the efficacy of the system was demonstrated through highly sensitive analysis of the protein digests or spiked glycopeptides.

Application of dynamic light scattering for studying the evolution of micro- and nano-droplets

NASA Astrophysics Data System (ADS)

Derkachov, G.; Jakubczyk, D.; Kolwas, K.; Shopa, Y.; Woźniak, M.; Wojciechowski, T.

2018-01-01

The dynamic light scattering (DLS) technique was used for studying the processes of aggregation of spherical SiO2 particles in various diethylene glycol (DEG) suspensions. The suspensions were studied in a cuvette, in a millimeter-sized droplet and in a micrometer-sized droplet. For the first time DLS signals for droplets of picolitre volume, levitated in an electrodynamic quadrupole trap, were obtained. It is shown that the correlation analysis of light scattered from a micro-droplet allows monitoring the changes of its internal structure, as well as its motions: trap-constricted Brownian motions and random rotations.

From Initial Nucleation to Cassie-Baxter State of Condensed Droplets on Nanotextured Superhydrophobic Surfaces

PubMed Central

Lv, Cunjing; Zhang, Xiwen; Niu, Fenglei; He, Feng; Hao, Pengfei

2017-01-01

Understanding how droplet condensation happens plays an essential role for our fundamental insights of wetting behaviors in nature and numerous applications. Since there is a lack of study of the initial formation and growing processes of condensed droplets down to nano-/submicroscale, relevant underlying mechanisms remain to be explored. We report an in situ observation of vapor condensation on nano-/microtextured superhydrophobic surfaces using optical microscopy. An interesting picture of the vapor condensation, from the initial appearance of individual small droplets (≤1 μm) to a Cassie-Baxter wetting state (>30 μm), are exhibited. It is found that individual droplets preferentially nucleate at the top and the edge of single micropillars with very high apparent contact angles on the nanotextures. Scenarios of two distinguished growing modes are reported statistically and the underlying mechanisms are discussed in the view of thermodynamics. We particularly reveal that the formation of the Cassie-Baxter wetting state is a result of a continuous coalescence of individual small droplets, in which the nanotexture-enhanced superhydrophobicity plays a crucial role. We envision that these fundamental findings can deepen our understanding of the nucleation and development of condensed droplets in nanoscale, so as to optimize design strategies of superhydrophobic materials for a broad range of water-harvesting and heat-transfer systems. PMID:28202939

A lattice Boltzmann model for substrates with regularly structured surface roughness

NASA Astrophysics Data System (ADS)

Yagub, A.; Farhat, H.; Kondaraju, S.; Singh, T.

2015-11-01

Superhydrophobic surface characteristics are important in many industrial applications, ranging from the textile to the military. It was observed that surfaces fabricated with nano/micro roughness can manipulate the droplet contact angle, thus providing an opportunity to control the droplet wetting characteristics. The Shan and Chen (SC) lattice Boltzmann model (LBM) is a good numerical tool, which holds strong potentials to qualify for simulating droplets wettability. This is due to its realistic nature of droplet contact angle (CA) prediction on flat smooth surfaces. But SC-LBM was not able to replicate the CA on rough surfaces because it lacks a real representation of the physics at work under these conditions. By using a correction factor to influence the interfacial tension within the asperities, the physical forces acting on the droplet at its contact lines were mimicked. This approach allowed the model to replicate some experimentally confirmed Wenzel and Cassie wetting cases. Regular roughness structures with different spacing were used to validate the study using the classical Wenzel and Cassie equations. The present work highlights the strength and weakness of the SC model and attempts to qualitatively conform it to the fundamental physics, which causes a change in the droplet apparent contact angle, when placed on nano/micro structured surfaces.

Tip-induced nanoreactor for silicate

NASA Astrophysics Data System (ADS)

Gao, Ming; Ma, Liran; Liang, Yong; Gao, Yuan; Luo, Jianbin

2015-09-01

Nanoscale scientific issues have attracted an increasing amount of research interest due to their specific size-effect and novel structure-property. From macro to nano, materials present some unique chemical reactivity that bulk materials do not own. Here we introduce a facile method to generate silicate with nanoscale control based on the establishment of a confined space between a meso/nanoscale tungsten tip and a smooth silica/silicon substrate. During the process, local water-like droplets deposition can be obviously observed in the confinement between the Si/SiO2 surfaces and the KOH-modified tungsten tip. By the combination of in-situ optical microscopy and Raman spectroscopy, we were able to take a deep insight of both the product composition and the underlying mechanism of such phenomena. It was indicated that such nanoreactor for silicate could be quite efficient as a result of the local capillarity and electric field effect, with implications at both nano and meso scales.

Tip-induced nanoreactor for silicate.

PubMed

Gao, Ming; Ma, Liran; Liang, Yong; Gao, Yuan; Luo, Jianbin

2015-09-14

Nanoscale scientific issues have attracted an increasing amount of research interest due to their specific size-effect and novel structure-property. From macro to nano, materials present some unique chemical reactivity that bulk materials do not own. Here we introduce a facile method to generate silicate with nanoscale control based on the establishment of a confined space between a meso/nanoscale tungsten tip and a smooth silica/silicon substrate. During the process, local water-like droplets deposition can be obviously observed in the confinement between the Si/SiO2 surfaces and the KOH-modified tungsten tip. By the combination of in-situ optical microscopy and Raman spectroscopy, we were able to take a deep insight of both the product composition and the underlying mechanism of such phenomena. It was indicated that such nanoreactor for silicate could be quite efficient as a result of the local capillarity and electric field effect, with implications at both nano and meso scales.

Tip-induced nanoreactor for silicate

PubMed Central

Gao, Ming; Ma, Liran; Liang, Yong; Gao, Yuan; Luo, Jianbin

2015-01-01

Nanoscale scientific issues have attracted an increasing amount of research interest due to their specific size-effect and novel structure-property. From macro to nano, materials present some unique chemical reactivity that bulk materials do not own. Here we introduce a facile method to generate silicate with nanoscale control based on the establishment of a confined space between a meso/nanoscale tungsten tip and a smooth silica/silicon substrate. During the process, local water-like droplets deposition can be obviously observed in the confinement between the Si/SiO2 surfaces and the KOH-modified tungsten tip. By the combination of in-situ optical microscopy and Raman spectroscopy, we were able to take a deep insight of both the product composition and the underlying mechanism of such phenomena. It was indicated that such nanoreactor for silicate could be quite efficient as a result of the local capillarity and electric field effect, with implications at both nano and meso scales. PMID:26364882

Hierarchical Micro/Nano Structures by Combined Self-Organized Dewetting and Photopatterning of Photoresist Thin Films.

PubMed

Sachan, Priyanka; Kulkarni, Manish; Sharma, Ashutosh

2015-11-17

Photoresists are the materials of choice for micro/nanopatterning and device fabrication but are rarely used as a self-assembly material. We report for the first time a novel interplay of self-assembly and photolithography for fabrication of hierarchical and ordered micro/nano structures. We create self-organized structures by the intensified dewetting of unstable thin (∼10 nm to 1 μm) photoresist films by annealing them in an optimal solvent and nonsolvent liquid mixture that allows spontaneous dewetting to form micro/nano smooth dome-like structures. The density, size (∼100 nm to millimeters), and curvature/contact angle of the dome/droplet structures are controlled by the film thickness, composition of the dewetting liquid, and time of annealing. Ordered dewetted structures are obtained simply by creating spatial variation of viscosity by ultraviolet exposure or by photopatterning before dewetting. Further, the structures thus fabricated are readily photopatterned again on the finer length scales after dewetting. We illustrate the approach by fabricating several three-dimensional structures of varying complexity with secondary and tertiary features.

Seeing Below the Drop: Direct Nano-to-microscale Imaging of Complex Interfaces involving Solid, Liquid, and Gas Phases

NASA Astrophysics Data System (ADS)

Rykaczewski, Konrad; Landin, Trevan; Walker, Marlon L.; Scott, John Henry J.; Varanasi, Kripa K.

2012-11-01

Nanostructured surfaces with special wetting properties have the potential to transform number of industries, including power generation, water desalination, gas and oil production, and microelectronics thermal management. Predicting the wetting properties of these surfaces requires detailed knowledge of the geometry and the composition of the contact volume linking the droplet to the underlying substrate. Surprisingly, a general nano-to-microscale method for direct imaging of such interfaces has previously not been developed. Here we introduce a three dimensional imaging method which resolves this one-hundred-year-old metrology gap in wetting research. Specifically, we demonstrate direct nano-to-microscale imaging of complex fluidic interfaces using cryofixation in combination with cryo-FIB/SEM. We show that application of this method yields previously unattainable quantitative information about the interfacial geometry of water condensed on silicon nanowire forests with hydrophilic and hydrophobic surface termination in the presence or absence of an intermediate water repelling oil. We also discuss imaging artifacts and the advantages of secondary and backscatter electron imaging, Energy Dispersive Spectrometry (EDS), and three dimensional FIB/SEM tomography.

Shock Initiated Reactions of Reactive Multiphase Blast Explosives

NASA Astrophysics Data System (ADS)

Wilson, Dennis; Granier, John; Johnson, Richard; Littrell, Donald

2015-06-01

This paper describes a new class of reactive multiphase blast explosives (RMBX) and characterization of their blast characteristics. These RMBXs are non-ideal explosive compositions of perfluoropolyether (PFPE), nano aluminum, and a micron-size high-density reactive metal - Tantalum, Zirconium, or Zinc in mass loadings of 66 to 83 percent. Unlike high explosives, these PFPE-metal compositions release energy via a fast self-oxidized combustion wave (rather than a true self-sustaining detonation) that is shock dependent, and can be overdriven to control energy release rate. The term ``reactive multiphase blast'' refers to the post-dispersion blast behavior: multiphase in that there are a gas phase that imparts pressure and a solid (particulate) phase that imparts momentum; and reactive in that the hot metal particles react with atmospheric oxygen and the explosive gas products to give an extended pressure pulse. The RMBX formulations were tested in two spherical core-shell geometries - an RMBX shell exploded by a high explosive core, and an RMBX core imploded by a high explosive shell. The fireball and blast characteristics were compared to a C-4 baseline charge.

Development of ingan quantum dots by the Stranski-Krastanov method and droplet heteroepitaxy

NASA Astrophysics Data System (ADS)

Woodward, Jeffrey Michael

The development of InGaN quantum dots (QDs) is both scienti?cally challenging and promising for applications in visible spectrum LEDs, lasers, detectors, electroabsorption modulators and photovoltaics. Such QDs are typically grown using the Stranski-Krastanov (SK) growth mode, in which accumulated in-plane compressive strain induces a transition from 2D to 3D growth. This method has a number of inherent limitations, including the unavoidable formation of a 2D wetting layer and the di?culty of controlling the composition, areal density, and size of the dots. In this research, I have developed InGaN QDs by two methods using a plasma-assisted molecular beam epitaxy reactor. In the ?rst method, InGaN QDs were formed by SK growth mode on (0001) GaN/sapphire. In the second, I have addressed the limitations of the SK growth of InGaN QDs by developing a novel alternative method, which was utilized to grow on both (0001) GaN/sapphire and AlN/sapphire. This method relies upon the ability to form thermodynamically stable In-Ga liquid solutions throughout the entire compositional range at relatively low temperatures. Upon simultaneous or sequential deposition of In and Ga on a substrate, the adatoms form a liquid solution, whose composition is controlled by the ratio of the fluxes of the two constituents FIn/(FIn+FGa ). Depending on the interfacial free energy between the liquid deposit and substrate, the liquid deposit and vapor, and the vapor and substrate, the liquid deposit forms Inx-Ga1- x nano-droplets on the substrate. These nano-droplets convert into InxGa1-xN QDs upon exposure to nitrogen RF plasma. InGaN QDs produced by both methods were investigated in-situ by reflection high-energy electron diffraction and ex-situ by atomic force microscopy, field emission scanning electron microscopy, transmission electron microscopy, high resolution x-ray diffraction, and grazing incidence small angle x-ray scattering. The optical activity and device potential of the QDs were investigated by photoluminescence measurements and the formation and evaluation of PIN devices (in which the intrinsic region contains QDs embedded within a higher bandgap matrix). InGaN QDs with areal densities ranging from 109 to 1011 cm -2 and diameters ranging from 11 to 39 nm were achieved.

Nanoscale Footprints of Self-Running Gallium Droplets on GaAs Surface

PubMed Central

Wu, Jiang; Wang, Zhiming M.; Li, Alvason Z.; Benamara, Mourad; Li, Shibin; Salamo, Gregory J.

2011-01-01

In this work, the nanoscale footprints of self-driven liquid gallium droplet movement on a GaAs (001) surface will be presented and analyzed. The nanoscale footprints of a primary droplet trail and ordered secondary droplets along primary droplet trails are observed on the GaAs surface. A well ordered nanoterrace from the trail is left behind by a running droplet. In addition, collision events between two running droplets are investigated. The exposed fresh surface after a collision demonstrates a superior evaporation property. Based on the observation of droplet evolution at different stages as well as nanoscale footprints, a schematic diagram of droplet evolution is outlined in an attempt to understand the phenomenon of stick-slip droplet motion on the GaAs surface. The present study adds another piece of work to obtain the physical picture of a stick-slip self-driven mechanism in nanoscale, bridging nano and micro systems. PMID:21673965

The comparison of CHCA solvent compositions for improving LC-MALDI performance and its application to study the impact of aflatoxin B1 on the liver proteome of diabetes mellitus type 1 mice.

PubMed

Tsai, Fuu-Jen; Chen, Shih-Yin; Liu, Yu-Ching; Liao, Hsin-Yi; Chen, Chao-Jung

2017-01-01

In nanoflow liquid chromatography-matrix-assisted laser desorption/ionization tandem time-of-flight (nanoLC-MALDI-TOF/TOF) approaches, it is critical to directly apply small amounts of the sample elutes on the sample target using a nanoLC system due to its low flow rate of 200 ~ 300 nl/min. It is recommended to apply a sheath liquid containing a matrix with a several μL/min flow rate at the end of the nanoLC column to ensure a larger co-eluted droplet for more reproducible sample spotting and avoid the laborious task of post-manual matrix spotting. In this study, to achieve a better nanoLC-MALDI performance on sample spotting, we first compared α-Cyano-4-hydroxycinnamic acid (CHCA) solvent composition for efficiently concentrating nanoLC elutes on an anchor chip. The solvent composition of isopropanol (IPA): acetonitrile (ACN):acetone:0.1% Trifluoroacetic acid (TFA) (2:7:7:2) provided strong and homogeneous signals with higher peptide ion yields than the other solvent compositions. Then, nanoLC-MALDI-TOF/TOF was applied to study the impact of aflatoxin B1 on the liver proteome from diabetes mellitus type 1 mice. Aflatoxin B1 (AFB1), produced by Aspergillus flavus and Aspergillus parasiticus is a carcinogen and a known causative agent of liver cancer. To evaluate the effects of long-term exposure to AFB1 on type 1 diabetes mellitus (TIDM), the livers of T1DM control mice and mice treated with AFB1 were analyzed using isotope-coded protein labeling (ICPL)-based quantitative proteomics. Our results showed that gluconeogenesis, lipid, and oxidative phosphorylation mechanisms, normally elevated in T1DM, were disordered following AFB1 treatment. In addition, major urinary protein 1 (MUP1), an indicator of increased insulin sensitivity, was significantly decreased in the T1DM/AFB1 group and may have resulted in higher blood glucose levels compared to the T1DM group. These results indicate that T1DM patients should avoid the AFB1 intake, as they could lead to increased blood glucose levels and disorders of energy-producing mechanisms.

How surface functional groups influence fracturation in nanofluids droplets dry-outs

NASA Astrophysics Data System (ADS)

Brutin, David; Carle, Florian

2012-11-01

We report an experimental investigation of the drying of a deposited droplets of nanofluids with different surface functional groups. For identical nano-particles diameter, material and concentration, identical drying conditions, the substrate and the functional groups at the nano-particles surface are changed. Both flow motion, adhesion, gelation and fracturation occur during the evaporation of this complex matter leading to different final typical patterns. The differences in between the patterns are explained based on the surface chemical potential. Crack shapes and wavelengths are globally proportional to the electrical charges carried at the nano- particles surface which is a new parameter to implement in existing predicting models. Presently only the colloid concentration and softness and the deposit thickness are used (Allain and Limat, 1995). The authors gratefully acknowledge the help and the fruitful discussions raised with J.B. Lang.

Direct Observation of Zhang-Li Torque Expansion of Magnetic Droplet Solitons

NASA Astrophysics Data System (ADS)

Chung, Sunjae; Le, Q. Tuan; Ahlberg, Martina; Awad, Ahmad A.; Weigand, Markus; Bykova, Iuliia; Khymyn, Roman; Dvornik, Mykola; Mazraati, Hamid; Houshang, Afshin; Jiang, Sheng; Nguyen, T. N. Anh; Goering, Eberhard; Schütz, Gisela; Gräfe, Joachim; Åkerman, Johan

2018-05-01

Magnetic droplets are nontopological dynamical solitons that can be nucleated in nanocontact based spin torque nano-oscillators (STNOs) with perpendicular magnetic anisotropy free layers. While theory predicts that the droplet should be of the same size as the nanocontact, its inherent drift instability has thwarted attempts at observing it directly using microscopy techniques. Here, we demonstrate highly stable magnetic droplets in all-perpendicular STNOs and present the first detailed droplet images using scanning transmission X-ray microscopy. In contrast to theoretical predictions, we find that the droplet diameter is about twice as large as the nanocontact. By extending the original droplet theory to properly account for the lateral current spread underneath the nanocontact, we show that the large discrepancy primarily arises from current-in-plane Zhang-Li torque adding an outward pressure on the droplet perimeter. Electrical measurements on droplets nucleated using a reversed current in the antiparallel state corroborate this picture.

Phenomenology and control of buckling dynamics in multicomponent colloidal droplets

NASA Astrophysics Data System (ADS)

Pathak, Binita; Basu, Saptarshi

2015-06-01

Self-assembly of nano sized particles during natural drying causes agglomeration and shell formation at the surface of micron sized droplets. The shell undergoes sol-gel transition leading to buckling at the weakest point on the surface and produces different types of structures. Manipulation of the buckling rate with inclusion of surfactant (sodium dodecyl sulphate, SDS) and salt (anilinium hydrochloride, AHC) to the nano-sized particle dispersion (nanosilica) is reported here in an acoustically levitated single droplet. Buckling in levitated droplets is a cumulative, complicated function of acoustic streaming, chemistry, agglomeration rate, porosity, radius of curvature, and elastic energy of shell. We put forward our hypothesis on how buckling occurs and can be suppressed during natural drying of the droplets. Global precipitation of aggregates due to slow drying of surfactant-added droplets (no added salts) enhances the rigidity of the shell formed and hence reduces the buckling probability of the shell. On the contrary, adsorption of SDS aggregates on salt ions facilitates the buckling phenomenon with an addition of minute concentration of the aniline salt to the dispersion. Variation in the concentration of the added particles (SDS/AHC) also leads to starkly different morphologies and transient behaviour of buckling (buckling modes like paraboloid, ellipsoid, and buckling rates). Tuning of the buckling rate causes a transition in the final morphology from ring and bowl shapes to cocoon type of structure.

Self-Assembly of Diblock Molecular Polymer Brushes in the Spherical Confinement of Nanoemulsion Droplets.

PubMed

Steinhaus, Andrea; Pelras, Théophile; Chakroun, Ramzi; Gröschel, André H; Müllner, Markus

2018-05-02

Understanding the self-assembly behavior of polymers of various topologies is key to a reliable design of functional polymer materials. Self-assembly under confinement conditions emerges as a versatile avenue to design polymer particles with complex internal morphologies while simultaneously facilitating scale-up. However, only linear block copolymers have been studied to date, despite the increasing control over macromolecule composition and architecture available. This study extends the investigation of polymer self-assembly in confinement from regular diblock copolymers to diblock molecular polymer brushes (MPBs). Block-type MPBs with polystyrene (PS) and polylactide (PLA) compartments of different sizes are incorporated into surfactant-stabilized oil-in-water (chloroform/water) emulsions. The increasing confinement in the nanoemulsion droplets during solvent evaporation directs the MPBs to form solid nano/microparticles. Microscopy studies reveal an intricate internal particle structure, including interpenetrating networks and axially stacked lamellae of PS and PLA, depending on the PS/PLA ratio of the brushes. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

A Computational Study of the Rheology and Structure of Surfactant Covered Droplets

NASA Astrophysics Data System (ADS)

Maia, Joao; Boromand, Arman; Jamali, Safa

2015-11-01

The use of different types of surface-active agents is ubiquitous practice in different industrial applications ranging from cosmetic and food industries to polymeric nano-composite and blends. This allows stable multiphasic systems like foams and emulsions to be produced. Stability and shelf-life of those products are directly determined by the efficiency of the surfactant molecules. Although the effect of molecular configuration of the surface-active molecules on the planar interfaces has been studied both experimentally and computationally, it remains challenging to track the efficiency and effectiveness of different surfactant molecules on curved interfaces. In this study we address this gap by using Dissipative Particle Dynamics, to study the effectiveness and efficiency of different surfactant molecules (linear vs. branched) on a curved interface in equilibrium and far from equilibrium. In particular, we are interested to relate interfacial properties of the surface covered droplets and its dynamics to the molecular configuration of the surface active molecules under equilibrium and far from equilibrium condition.

Development of a novel nanoscratch technique for quantitative measurement of ice adhesion strength

NASA Astrophysics Data System (ADS)

Loho, T.; Dickinson, M.

2018-04-01

The mechanism for the way that ice adheres to surfaces is still not well understood. Currently there is no standard method to quantitatively measure how ice adheres to surfaces which makes ice surface studies difficult to compare. A novel quantitative lateral force adhesion measurement at the micro-nano scale for ice was created which shears micro-nano sized ice droplets (less than 3 μm in diameter and 100nm in height) using a nanoindenter. By using small ice droplets, the variables associated with bulk ice measurements were minimised which increased data repeatability compared to bulk testing. The technique provided post- testing surface scans to confirm that the ice had been removed and that measurements were of ice adhesion strength. Results show that the ice adhesion strength of a material is greatly affected by the nano-scale surface roughness of the material with rougher surfaces having higher ice adhesion strength.

Computing fluid-particle interaction forces for nano-suspension droplet spreading: molecular dynamics simulations

NASA Astrophysics Data System (ADS)

Zhou, Weizhou; Shi, Baiou; Webb, Edmund

2017-11-01

Recently, there are many experimental and theoretical studies to understand and control the dynamic spreading of nano-suspension droplets on solid surfaces. However, fundamental understanding of driving forces dictating the kinetics of nano-suspension wetting and spreading, especially capillary forces that manifest during the process, is lacking. Here, we present results from atomic scale simulations that were used to compute forces between suspended particles and advancing liquid fronts. The role of nano-particle size, particle loading, and interaction strength on forces computed from simulations will be discussed. Results demonstrate that increasing the particle size dramatically changes observed wetting behavior from depinning to pinning. From simulations on varying particle size, a relationship between computed forces and particle size is advanced and compared to existing expressions in the literature. High particle loading significantly slowed spreading kinetics, by introducing tortuous transport paths for liquid delivery to the advancing contact line. Lastly, we show how weakening the interaction between the particle and the underlying substrate can change a system from exhibiting pinning behavior to de-pinning.

Nano-scaled top-down of bismuth chalcogenides based on electrochemical lithium intercalation

NASA Astrophysics Data System (ADS)

Chen, Jikun; Zhu, Yingjie; Chen, Nuofu; Liu, Xinling; Sun, Zhengliang; Huang, Zhenghong; Kang, Feiyu; Gao, Qiuming; Jiang, Jun; Chen, Lidong

2011-12-01

A two-step method has been used to fabricate nano-particles of layer-structured bismuth chalcogenide compounds, including Bi2Te3, Bi2Se3, and Bi2Se0.3Te2.7, through a nano-scaled top-down route. In the first step, lithium (Li) atoms are intercalated between the van der Waals bonded quintuple layers of bismuth chalcogenide compounds by controllable electrochemical process inside self-designed lithium ion batteries. And in the second step, the Li intercalated bismuth chalcogenides are subsequently exposed to ethanol, in which process the intercalated Li atoms would explode like atom-scaled bombs to exfoliate original microscaled powder into nano-scaled particles with size around 10 nm. The influence of lithium intercalation speed and amount to three types of bismuth chalcogenide compounds are compared and the optimized intercalation conditions are explored. As to maintain the phase purity of the final nano-particle product, the intercalation lithium amount should be well controlled in Se contained bismuth chalcogenide compounds. Besides, compared with binary bismuth chalcogenide compound, lower lithium intercalation speed should be applied in ternary bismuth chalcogenide compound.

Surfactant induced stabilization of nano liquid crystalline (dodecane-phytantriol) droplet

NASA Astrophysics Data System (ADS)

Abbas, S.; Saha, Debasish; Kumar, Sugam; Aswal, V. K.; Kohlbrecher, J.

2018-04-01

The study of formation and stabilization of dodecane-phytantriol (DPT) microemulsions using ionic and nonionic surfactants are investigated. Small Angle Neutron Scattering (SANS) and Dynamic Light Scattering (DLS) techniques have been employed to study the resulting structures of the micro emulsion droplets. We show the formation of stable microemulsion droplets with absence of lyotropic liquid crystalline phase on addition of nonionic surfactant C12E10. The oil to surfactant ratio plays the crucial role in formation of stable droplet and its size. The dense presence of C12E10 molecules between microemulsion droplets protect them from coalescence while less number of C12E10 between the surface of droplets easily triggers the coalescence process. The interaction with both anionic (SDS) as well as cationic (DTAB) surfactants with DPT phase leads to formation of microemulsion droplets with lyotropic liquid crystalline phase.

Phase behavior and formation of o/w nano-emulsion in vegetable oil/ mixture of polyglycerol polyricinoleate and polyglycerin fatty acid ester/water systems.

PubMed

Wakisaka, Satoshi; Nakanishi, Masami; Gohtani, Shoichi

2014-01-01

It is reported that mixing polyglycerol polyricinoleate (PGPR) and polyglycerol laurilester has a great emulsifying capacity, and consequently fine oil-in-water (o/w) emulsions can be formed. However, the role of PGPR is not clear. The objective of this research is to investigate the phase behavior of vegetable oil/mixture of PGPR and polyglycerol fatty acid ester/water systems, and to clarify the role of PGPR in making a fine emulsion. Phase diagrams were constructed to elucidate the optimal process for preparing fine emulsions. In all the systems examined in this study, the phases, including the liquid crystal phase (L(c)) and sponge phase (L(3)), spread widely in the phase diagrams. We examined droplet size of the emulsions prepared from each phase and found that o/w nano-emulsions with droplet sizes as small as 50 nm were formed by emulsifying either from a single L(3) phase or a two-phase region, L(c) + L(3). These results indicate that a sponge phase L(3) or liquid crystal phase L(c) or both is necessary to form an o/w nano-emulsion whose average droplet diameter is less than 50 nm for PGPR and polyglycerin fatty acid ester mixtures used as surfactant.

In situ observation on the dynamic process of evaporation and crystallization of sodium nitrate droplets on a ZnSe substrate by FTIR-ATR.

PubMed

Zhang, Qing-Nuan; Zhang, Yun; Cai, Chen; Guo, Yu-Cong; Reid, Jonathan P; Zhang, Yun-Hong

2014-04-17

Sodium nitrate is a main component of aging sea salt aerosol, and its phase behavior has been studied repeatedly with wide ranges observed in the efflorescence relative humidity (RH) in particular. Studies of the efflorescence dynamics of NaNO3 droplets deposited on a ZnSe substrate are reported, using an in situ Fourier transform infrared attenuated total reflection (FTIR-ATR) technique. The time-dependence of the infrared spectra of NaNO3 aerosols accompanying step changes in RH have been measured with high signal-to-noise ratio. From the IR difference spectra recorded, changes of the time-dependent absorption peak area of the O-H stretching band (ν-OH, ∼3400 cm(-1)) and the nitrate out-of-plane bending band (ν2-NO3(-), ∼836 cm(-1)) are obtained. From these measurements, changes in the IR signatures can be attributed to crystalline and solution phase nitrate ions, allowing the volume fraction of the solution droplets that have crystallized to be determined. Then, using these clear signatures of the volume fraction of droplets that have yet to crystallize, the homogeneous and heterogeneous nucleation kinetics can be studied from conventional measurements using a steady decline in RH. The nucleation rate measurements confirm that the rate of crystallization in sodium nitrate droplets is considerably less than in ammonium sulfate droplets at any particular degree of solute supersaturation, explaining the wide range of efflorescence RHs observed for sodium nitrate in previous studies. We demonstrate that studying nucleation kinetics using the FTIR-ATR approach has many advantages over brightfield imaging studies on smaller numbers of larger droplets or measurements made on single levitated particles.

Combinatorial microfluidic droplet engineering for biomimetic material synthesis

PubMed Central

Bawazer, Lukmaan A.; McNally, Ciara S.; Empson, Christopher J.; Marchant, William J.; Comyn, Tim P.; Niu, Xize; Cho, Soongwon; McPherson, Michael J.; Binks, Bernard P.; deMello, Andrew; Meldrum, Fiona C.

2016-01-01

Although droplet-based systems are used in a wide range of technologies, opportunities for systematically customizing their interface chemistries remain relatively unexplored. This article describes a new microfluidic strategy for rapidly tailoring emulsion droplet compositions and properties. The approach uses a simple platform for screening arrays of droplet-based microfluidic devices and couples this with combinatorial selection of the droplet compositions. Through the application of genetic algorithms over multiple screening rounds, droplets with target properties can be rapidly generated. The potential of this method is demonstrated by creating droplets with enhanced stability, where this is achieved by selecting carrier fluid chemistries that promote titanium dioxide formation at the droplet interfaces. The interface is a mixture of amorphous and crystalline phases, and the resulting composite droplets are biocompatible, supporting in vitro protein expression in their interiors. This general strategy will find widespread application in advancing emulsion properties for use in chemistry, biology, materials, and medicine. PMID:27730209

Aqueous Processing of Atmospheric Organic Particles in Cloud Water Collected via Aircraft Sampling.

PubMed

Boone, Eric J; Laskin, Alexander; Laskin, Julia; Wirth, Christopher; Shepson, Paul B; Stirm, Brian H; Pratt, Kerri A

2015-07-21

Cloudwater and below-cloud atmospheric particle samples were collected onboard a research aircraft during the Southern Oxidant and Aerosol Study (SOAS) over a forested region of Alabama in June 2013. The organic molecular composition of the samples was studied to gain insights into the aqueous-phase processing of organic compounds within cloud droplets. High resolution mass spectrometry (HRMS) with nanospray desorption electrospray ionization (nano-DESI) and direct infusion electrospray ionization (ESI) were utilized to compare the organic composition of the particle and cloudwater samples, respectively. Isoprene and monoterpene-derived organosulfates and oligomers were identified in both the particles and cloudwater, showing the significant influence of biogenic volatile organic compound oxidation above the forested region. While the average O:C ratios of the organic compounds were similar between the atmospheric particle and cloudwater samples, the chemical composition of these samples was quite different. Specifically, hydrolysis of organosulfates and formation of nitrogen-containing compounds were observed for the cloudwater when compared to the atmospheric particle samples, demonstrating that cloud processing changes the composition of organic aerosol.

Cryptoachneliths: Hidden glassy ash in composite spheroidal lapilli

NASA Astrophysics Data System (ADS)

Carracedo Sánchez, M.; Arostegui, J.; Sarrionandia, F.; Larrondo, E.; Gil Ibarguchi, J. I.

2010-09-01

Cryptoachneliths, perceptible by means of electron microscopy but unresolved under the optical microscope, occur unnoticed inside spheroidal lapilli of ultrabasic composition of the Cabezo Segura volcano (Calatrava volcanic province, Spain). The cryptoachneliths are glassy spherical particles that have compositions of Al-rich silicate with minor amounts of Fe, Ca and other elements. The smallest cryptoachneliths of < 1 μm in diameter (nanoachneliths) joined by coalescence to form microspheres > 1 μm (microachneliths) and homogeneous less regular masses of similar composition. Nano and microachneliths welded each other or to other types of volcanic particles (crystals, crystal fragments, spinning droplets, cognate lithic clasts, etc.) to form spheroidal lapilli and even bomb size clasts within proximal fall deposits of the Cabezo Segura volcano. The welding processes took place inside the eruptive column, previous to the fall of the spheroidal lapilli on top of the volcanic cone. The presence of the cryptoachneliths implies that lapilli and even bomb size tephra within deposits formed during explosive eruptions of low-viscosity basic to ultrabasic magmas should be carefully examined in order to establish key parameters of eruption dynamics, like size, amount and distribution of juvenile fine particles.

Development of novel nano-composite membranes as introduction systems for mass spectrometers: Contrasting nano-composite membranes and conventional inlet systems

NASA Astrophysics Data System (ADS)

Miranda, Luis Diego

This dissertation presents the development of novel nano-composite membranes as introduction systems for mass spectrometers. These nano-composite membranes incorporate anodic aluminum oxide (AAO) membranes as templates that can be used by themselves or modified by a variety of chemical deposition processes. Two types of nano-composite membranes are presented. The first nano-composite membrane has carbon deposited within the pores of an AAO membrane. The second nano-composite membrane is made by coating an AAO membrane with a thin polymer film. The following chapters describe the transmission properties these nano-composite membranes and compare them to conventional mass spectrometry introduction systems. The nano- composite membranes were finally coupled to the inlet system of an underwater mass spectrometer revealing their utility in field deployments.

DebriSat Laboratory Analyses

DTIC Science & Technology

2015-01-05

droplets. Fluorine from Teflon wire insulation was also common in the SEM stub and witness plates deposits. Nano droplets of metallic materials...and Debris-LV debris. Aluminum was from the Al honeycomb, nadir and zenith panels, structural core and COPV liner. Aluminum oxide particles were...three pieces: Outer Nylon shell (sabot) with 2 part hollow aluminum insert. • ~600 grams, 8.6 cm diameter X 10.3 cm long – size of a soup can

Exploratory Experiments in the Tribological Behavior of Engineering Surfaces with Nano-Coating Using a Tribo-Rheometer

DTIC Science & Technology

2008-05-30

Tribological behavior and graphitization of carbon nanotubes grown on 440C stainless steel . Tribo. Lett., 19(2):119-125, 2005. D-2 ...with a stainless steel parallel plate configuration as shown in figure 1. Due to the radial variation of the local shear stress T in the parallel...using a force transducer that is mounted below the surface. B-1 Exploded View Stainless Steel Plate Lower Fixture Microscale View Figure 1:

Comparision on dynamic behavior of diesel spray and rapeseed oil spray in diesel engine

NASA Astrophysics Data System (ADS)

Sapit, Azwan; Azahari Razali, Mohd; Faisal Hushim, Mohd; Jaat, Norrizam; Nizam Mohammad, Akmal; Khalid, Amir

2017-04-01

Fuel-air mixing is important process in diesel combustion. It significantly affects the combustion and emission of diesel engine. Biomass fuel has high viscosity and high distillation temperature and may negatively affect the fuel-air mixing process. Thus, study on the spray development and atomization of this type of fuel is important. This study investigates the atomization characteristics and droplet dynamic behaviors of diesel engine spray fuelled by rapeseed oil (RO) and comparison to diesel fuel (GO). Optical observation of RO spray was carried out using shadowgraph photography technique. Single nano-spark photography technique was used to study the characteristics of the spray while dual nano-spark shadowgraph technique was used to study the spray droplet behavior. Using in-house image processing algorithm, the images were processed and the boundary condition of each spray was also studied. The results show that RO has very poor atomization due to the high viscosity nature of the fuel when compared to GO. This is in agreement with the results from spray droplet dynamic behavior studies that shows due to the high viscosity, the RO spray droplets are large in size and travel downward, with very little influence of entrainment effect due to its large kinematic energy.

Preparation and optimization of tablets containing a self-nano-emulsifying drug delivery system loaded with rosuvastatin.

PubMed

Salem, Heba F; Kharshoum, Rasha M; Halawa, Abdel Khalek A; Naguib, Demiana M

2018-06-01

Rosuvastatin (ROS) calcium is the latest synthetic drug in the statin group that has an anti-hyperlipidemic activity. It is available as tablets, and its poor aqueous solubility, slow dissolution rate and low-absorption extent result in less than 20% bioavailability and about 80% being excreted unchanged in the feces without absorption. To utilize nanotechnology to reformulate ROS as a self-nano-emulsifying drug delivery system (SNEDDS), and utilizing design optimization to fabricate the SNEDDS as a tablet. The solubility of ROS in different oils, surfactants and co-surfactants was tested. Pseudo-ternary phase diagrams were developed and various SNEDDS formulations were prepared and evaluated regarding globule size, self-emulsification, viscosity and transmittance. The optimized system was examined using transmission electron microscopy. The self-nano-emulsifying tablets were prepared using two types of nano-silica and different percentages of Avicel as a binder and Ac-Di-Sol as a disintegrant. The prepared tablets were evaluated for their physicochemical properties. Bioavailability in human volunteers was assessed. A SNEDDS system was successfully developed with a droplet size range of 15 nm and a composition of 10% Labrafac, 80% Cremophore RH40 and 10% Propylene glycol. The optimized tablet formula contained: hydrophilic nano-silica, 3% Ac-Di-Sol and 30% Avicel. The pharmacokinetic study revealed that the bioavailability was enhanced by more than 2.4-fold compared with the commercially available tablet. Tablets containing SNEDDS loaded with ROS represent a promising novel formula that has higher gastrointestinal absorption and enhanced systemic bioavailability.

Preparation of hybrid nano biocomposite κ-carrageenan/cellulose nanocrystal/nanoclay

NASA Astrophysics Data System (ADS)

Zakuwan, Siti Zarina; Ahmad, Ishak; Ramli, Nazaruddin

2013-11-01

Biodegradable composites film based on κ-carrageenan and nano particles as filler was prepared to study the mechanical strength of carrageenan composites. Solution casting technique was used to prepare_this biocomposite. Preparation of composite film and nano filler involve two stages, preparation of cellulose nanocrystals (CNC) from kenaf with alkali treatment, bleaching, and hydrolysis followed by the preparation of two types of nano composite. Tensile test was carried on the composite film based on κ-carrageenan with the variation percentage of CNC and nano clay to obtain the optimum CNC and nano clay loading. After that hybrid nano-biocomposite film based on κ-carrageenan with the variation percentage of CNC/nano clay (OMMT) according to optimum value of composite carrageenan/CNC and composite carrageenan/nano clay film was prepared. The effect of nano filler on the mechanical properties of carrageenan films was examined. κ-carrageenan biocomposite increased with the optimum at 4% CNC and nano clay composition. Additional improvement of tensile strength with hybridization of CNC and nanoclay indicated better mechanical properties.

Distillation-based Droplet Modeling of Non-Ideal Oxygenated Gasoline Blends: Investigating the Role of Droplet Evaporation on PM Emissions

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

Burke, Stephen C.; Ratcliff, Matthew; McCormick, Robert

In some studies, a relationship has been observed between increasing ethanol content in gasoline and increased particulate matter (PM) emissions from vehicles equipped with spark ignition engines. The fundamental cause of the PM increase seen for moderate ethanol concentrations is not well understood. Ethanol features a greater heat of vaporization (HOV) than gasoline and also influences vaporization by altering the liquid and vapor composition throughout the distillation process. A droplet vaporization model was developed to explore ethanol's effect on the evaporation of aromatic compounds known to be PM precursors. The evolving droplet composition is modeled as a distillation process, withmore » non-ideal interactions between oxygenates and hydrocarbons accounted for using UNIFAC group contribution theory. Predicted composition and distillation curves were validated by experiments. Detailed hydrocarbon analysis was applied to fuel samples and to distillate fractions, and used as input for the initial droplet composition. With composition calculated throughout the distillation, the changing HOV and other physical properties can be found using reference data. The droplet can thus be modeled in terms of energy transfer, which in turn provides the transient mass transfer, droplet temperature, and droplet diameter. Model predictions suggest that non-ideal vapor-liquid equilibrium along with an increase in HOV can alter the droplet composition evolution. Results predict that the presence of ethanol causes enrichment of the higher boiling fractions (T90+) in the aromatic components as well as lengthens the droplet lifetime. A simulation of the evaporation process in a transient environment as experienced within an engine cylinder predicts a decrease in mixing time of the heaviest fractions of the fuel prior to spark initiation, possibly explaining observations linking ethanol to PM.« less

Distillation-based Droplet Modeling of Non-Ideal Oxygenated Gasoline Blends: Investigating the Role of Droplet Evaporation on PM Emissions

DOE PAGES

Burke, Stephen C.; Ratcliff, Matthew; McCormick, Robert; ...

2017-03-28

In some studies, a relationship has been observed between increasing ethanol content in gasoline and increased particulate matter (PM) emissions from vehicles equipped with spark ignition engines. The fundamental cause of the PM increase seen for moderate ethanol concentrations is not well understood. Ethanol features a greater heat of vaporization (HOV) than gasoline and also influences vaporization by altering the liquid and vapor composition throughout the distillation process. A droplet vaporization model was developed to explore ethanol's effect on the evaporation of aromatic compounds known to be PM precursors. The evolving droplet composition is modeled as a distillation process, withmore » non-ideal interactions between oxygenates and hydrocarbons accounted for using UNIFAC group contribution theory. Predicted composition and distillation curves were validated by experiments. Detailed hydrocarbon analysis was applied to fuel samples and to distillate fractions, and used as input for the initial droplet composition. With composition calculated throughout the distillation, the changing HOV and other physical properties can be found using reference data. The droplet can thus be modeled in terms of energy transfer, which in turn provides the transient mass transfer, droplet temperature, and droplet diameter. Model predictions suggest that non-ideal vapor-liquid equilibrium along with an increase in HOV can alter the droplet composition evolution. Results predict that the presence of ethanol causes enrichment of the higher boiling fractions (T90+) in the aromatic components as well as lengthens the droplet lifetime. A simulation of the evaporation process in a transient environment as experienced within an engine cylinder predicts a decrease in mixing time of the heaviest fractions of the fuel prior to spark initiation, possibly explaining observations linking ethanol to PM.« less

Stable superhydrophilic coating on superhydrophobic porous media by functionalized nanoparticles

NASA Astrophysics Data System (ADS)

Khazaei, Masoud; Taghi Sadeghi, Mohammad; Sadat Hosseini, Marzieh

2018-01-01

In this study, the hydrophilicity property of TiO2 nano-coating was improved by zinc acetate-assisted sol-gel method. The stable superhydrophilic coating was fabricated on a superhydrophobic mineral rock surface. The wettability of surface before and after coating was characterized by contact angle measurements. The n-heptane and water droplet contact angle was 0° and 168° respectively, so the untreated rock was superhydrophobic. After nano-treatment, the n-heptane and water contact angle changed to 172° and 0° respectively, so the superhydrophilic coating was formed on the superhydrophobic surface. The thermal, mechanical and salinity stability of the fabricated coatings was investigated. The coatings had high thermal and salinity stability; they also had moderate mechanical stability that was evaluated by abrasion test. The morphology and composition of synthesized nanoparticles were characterized by scanning electron microscopy (SEM), Fourier transform infrared spectroscopy and x-ray diffraction (XRD) analyses. Characterization of the coated surfaces was conducted by SEM and XRD analyses. Applications of these nano-coatings include surfaces where cleanliness is paramount such as in hospitals as well as the protection of public monuments and building facades from weathering. Novel industrial application includes wettability alteration of oil wet carbonate rock for enhanced oil recovery.

Measuring the emulsification dynamics and stability of self-emulsifying drug delivery systems.

PubMed

Vasconcelos, Teófilo; Marques, Sara; Sarmento, Bruno

2018-02-01

Self-emulsifying drug delivery systems (SEDDS) are one of the most promising technologies in the drug delivery field, particularly for addressing solubility and bioavailability issues of drugs. The development of these drug carriers excessively relies in visual observations and indirect determinations. The present manuscript intended to describe a method able to measure the emulsification of SEDDS, both micro and nano-emulsions, able to measure the droplet size and to evaluate the physical stability of these formulations. Additionally, a new process to evaluate the physical stability of SEDDS after emulsification was also proposed, based on a cycle of mechanical stress followed by a resting period. The use of a multiparameter continuous evaluation during the emulsification process and stability was of upmost value to understand SEDDS emulsification process. Based on this method, SEDDS were classified as fast and slow emulsifiers. Moreover, emulsification process and stabilization of emulsion was subject of several considerations regarding the composition of SEDDS as major factor that affects stability to physical stress and the use of multicomponent with different properties to develop a stable and robust SEDDS formulation. Drug loading level is herein suggested to impact droplets size of SEDDS after dispersion and SEDDS stability to stress conditions. The proposed protocol allows an online measurement of SEDDS droplet size during emulsification and a rationale selection of excipients based on its emulsification and stabilization performance. Copyright © 2017. Published by Elsevier B.V.

A Rapid One-Step Process for Fabrication of Biomimetic Superhydrophobic Surfaces by Pulse Electrodeposition.

PubMed

Jiang, Shuzhen; Guo, Zhongning; Liu, Guixian; Gyimah, Glenn Kwabena; Li, Xiaoying; Dong, Hanshan

2017-10-25

Inspired by some typical plants such as lotus leaves, superhydrophobic surfaces are commonly prepared by a combination of low surface energy materials and hierarchical micro/nano structures. In this work, superhydrophobic surfaces on copper substrates were prepared by a rapid, facile one-step pulse electrodepositing process, with different duty ratios in an electrolyte containing lanthanum chloride (LaCl₃·6H₂O), myristic acid (CH₃(CH₂) 12 COOH), and ethanol. The equivalent electrolytic time was only 10 min. The surface morphology, chemical composition and superhydrophobic property of the pulse electrodeposited surfaces were fully investigated with SEM, EDX, XRD, contact angle meter and time-lapse photographs of water droplets bouncing method. The results show that the as-prepared surfaces have micro/nano dual scale structures mainly consisting of La[CH₃(CH₂) 12 COO]₃ crystals. The maximum water contact angle (WCA) is about 160.9°, and the corresponding sliding angle is about 5°. This method is time-saving and can be easily extended to other conductive materials, having a great potential for future applications.

A Rapid One-Step Process for Fabrication of Biomimetic Superhydrophobic Surfaces by Pulse Electrodeposition

PubMed Central

Jiang, Shuzhen; Guo, Zhongning; Liu, Guixian; Gyimah, Glenn Kwabena; Li, Xiaoying; Dong, Hanshan

2017-01-01

Inspired by some typical plants such as lotus leaves, superhydrophobic surfaces are commonly prepared by a combination of low surface energy materials and hierarchical micro/nano structures. In this work, superhydrophobic surfaces on copper substrates were prepared by a rapid, facile one-step pulse electrodepositing process, with different duty ratios in an electrolyte containing lanthanum chloride (LaCl3·6H2O), myristic acid (CH3(CH2)12COOH), and ethanol. The equivalent electrolytic time was only 10 min. The surface morphology, chemical composition and superhydrophobic property of the pulse electrodeposited surfaces were fully investigated with SEM, EDX, XRD, contact angle meter and time-lapse photographs of water droplets bouncing method. The results show that the as-prepared surfaces have micro/nano dual scale structures mainly consisting of La[CH3(CH2)12COO]3 crystals. The maximum water contact angle (WCA) is about 160.9°, and the corresponding sliding angle is about 5°. This method is time-saving and can be easily extended to other conductive materials, having a great potential for future applications. PMID:29068427

Responsiveness of emulsions stabilized by lactoferrin nano-particles to simulated intestinal conditions.

PubMed

Meshulam, Dafna; Lesmes, Uri

2014-01-01

There is an upsurge of interest in the use of nano-particles to fabricate emulsions and modulate their functionality, with particular emphasis on modulating emulsion digestive fate. Food grade nano-particles formed through controlled processing and electrostatic biopolymer interactions are yet to be systematically studied for their ability to stabilize emulsions and modulate emulsion digestibility. This study focused on the responsiveness of emulsions stabilized by lactoferrin (LF) nano-particles (NPs) and dietary fibers to key digestive parameters. Compared to native LF, LF-NPs comprised emulsion exhibited elevated creaming rates as evident from accelerated stability tests performed by analytical centrifugation. The electrostatic deposition of alginate or carrageenan onto the LF-NPs significantly improved the stability of the corresponding emulsions. Further, the use of various nano-particles showed to have both beneficial and deleterious effects on emulsion responsiveness to pH (2.0 < pH < 10.0), CaCl2 (0-40 mM) and bile (0-25 mg mL(-1)). Simulated pH-stat lipolysis experiments show that the use of LF or LF-NPs had no marked effect on lipolysis. Intriguingly, the use of LF-NPs and alginate reduced emulsion lipolysis by 14% while the use of LF-NPs and carrageenan increased lipolysis by 10%. Microscopy images as well as droplet characterization in terms of size and charge indicate that the altered emulsion responsiveness may be due to physical differences in emulsion properties (e.g. droplet size) and overall organization during digestion (e.g. aggregation vs. coalescence). Overall, this study's insights could prospectively be used to harness protein nano-particles to tweak emulsion behavior during digestion.

Nanoformulation of poly(ethylene glycol) polymerized organic insect repellent by PIT emulsification method and its application for Japanese encephalitis vector control.

PubMed

Balaji, A P B; Mishra, Prabhakar; Suresh Kumar, R S; Mukherjee, Amitava; Chandrasekaran, Natarajan

2015-04-01

The utilization of increased dosage of insect repellents to overcome mosquito resistance has raised environmental concerns globally. In accord to this, we have formulated an efficacious, water-dispersive, nanometric formulation of a poor water-soluble insect repellent, diethylphenylacetamide (DEPA) by poly(ethylene glycol) (PEG) polymerization followed by PIT emulsification method. The critical micelle concentration of PEG in the spontaneously emulsified conventional DEPA droplets was determined, based on the droplets physical stability. Subjecting them to PIT emulsification yielded monodispersed polymeric nanomicelles of DEPA (Nano DEPA) with hydrodynamic mean diameter of 153.74 nm. The high-resolution scanning and transmission electron microscopic studies revealed the characteristic core-shell structure of micelle. The comparative efficacy of Bulk DEPA and Nano DEPA was evaluated by larvicidal and WHO cone bioassay against the Japanese encephalitis vector Culex tritaeniorhynchus. The median lethal concentrations (48 h) for 3rd instars C. tritaeniorhynchus larvae were found to be 0.416 mg/L for Bulk DEPA and 0.052 mg/L for Nano DEPA, respectively. The median knockdown concentrations (60 min) for the two to three-day-old, sucrose-fed, female adult mosquitoes were 5.372% (v/v) and 3.471% (v/v) for Bulk and Nano DEPA, respectively. Further investigation by histopathological and biochemical studies propound that Nano DEPA exerted better bioefficacy as comparative to its bulk form even at minimal exposure concentrations. Hence, Nano DEPA will serve as an effective alternate in controlling the vector expansion with reduced dosage. Copyright © 2015 Elsevier B.V. All rights reserved.

Electrowetting in a water droplet with a movable floating substrate

NASA Astrophysics Data System (ADS)

Shahzad, Amir; Masud, A. R.; Song, Jang-Kun

2016-05-01

Electrowetting (EW) enables facile manipulation of a liquid droplet on a hydrophobic surface. In this study, manipulation of an electrolyte droplet having a small floating object on it was investigated on a solid hydrophobic substrate under the EW process. Herein, the floating object exhibited a vertical motion under an applied electric field owing to the spreading and contraction of the droplet on its connecting substrates. The field-induced height variation of the floating object was significantly influenced by the thicknesses of the dielectric and hydrophobic materials. A small mass was also placed on the top floating object and its effect on the spreading of the droplet was observed. In this system, the height of the top floating object is precisely controllable under the application of an electric voltage. The proposed system is expected to be highly useful in the design of nano- and micro-oscillatory systems for microengineering.

Electrowetting in a water droplet with a movable floating substrate.

PubMed

Shahzad, Amir; Masud, A R; Song, Jang-Kun

2016-05-01

Electrowetting (EW) enables facile manipulation of a liquid droplet on a hydrophobic surface. In this study, manipulation of an electrolyte droplet having a small floating object on it was investigated on a solid hydrophobic substrate under the EW process. Herein, the floating object exhibited a vertical motion under an applied electric field owing to the spreading and contraction of the droplet on its connecting substrates. The field-induced height variation of the floating object was significantly influenced by the thicknesses of the dielectric and hydrophobic materials. A small mass was also placed on the top floating object and its effect on the spreading of the droplet was observed. In this system, the height of the top floating object is precisely controllable under the application of an electric voltage. The proposed system is expected to be highly useful in the design of nano- and micro-oscillatory systems for microengineering.

Measurement of interaction between water droplets and curved super-hydrophobic substrates in the air

NASA Astrophysics Data System (ADS)

Wang, Zhiyi; Zhao, Meirong; Jiang, Jile; Zhang, Lele; Zhuang, Shuya; Zhao, Yuchen; Huang, Yinguo; Zheng, Yelong

2018-04-01

The interaction force is very important in the study of the contact process of droplets and super-hydrophobic substrates. Accurate interaction force measurement in the air has far-reaching impact on industrial production and biomimetic field. However, limited by the evaporation of small droplets, interaction force can only be measured in the liquid by AFM and other devices. A millimetric cantilever was used to make it possible to measure the interaction between droplets and super-hydrophobic substrates in the air. The optical lever was calibrated with the electrostatic force. The super- hydrophobic substrates were fabricated using nano particles and copper grids. We finally acquired the interaction force and wetting time between the droplet and super- hydrophobic substrates with different grid fractions and similar contact angle. The results showed that the interaction force decreased with the increase of the grid fraction. These would open a new way of understanding the mechanism of hydrophobic.

Droplet Microfluidics for Chip-Based Diagnostics

PubMed Central

Kaler, Karan V. I. S.; Prakash, Ravi

2014-01-01

Droplet microfluidics (DMF) is a fluidic handling technology that enables precision control over dispensing and subsequent manipulation of droplets in the volume range of microliters to picoliters, on a micro-fabricated device. There are several different droplet actuation methods, all of which can generate external stimuli, to either actively or passively control the shape and positioning of fluidic droplets over patterned substrates. In this review article, we focus on the operation and utility of electro-actuation-based DMF devices, which utilize one or more micro-/nano-patterned substrates to facilitate electric field-based handling of chemical and/or biological samples. The underlying theory of DMF actuations, device fabrication methods and integration of optical and opto-electronic detectors is discussed in this review. Example applications of such electro-actuation-based DMF devices have also been included, illustrating the various actuation methods and their utility in conducting chip-based laboratory and clinical diagnostic assays. PMID:25490590

Drop Impingement on Highly Wetting Micro/Nano Porous Surfaces

NASA Astrophysics Data System (ADS)

Buie, Cullen; Joung, Youngsoo

2011-11-01

Recently, we developed a novel fabrication method using a combination of electrophoretic deposition (EPD) and break down anodization (BDA) to achieve highly wetting nanoporous surfaces with microscale features. In this study we investigate droplet impingement behavior on these surfaces as a function of impact velocity, droplet size, and liquid properties. We observe impingement modes we denote as ``necking'' (droplet breaks before full penetration in the porous surface), ``spreading'' (continuous wicking into the porous surface), and ``jetting'' (jets of liquid emanate from the edges of the wicking liquid). To predict the droplet impingement modes, we've developed a non-dimensional parameter that is a function of droplet velocity, dynamic viscosity, effective pore radius and contact angle. The novel dimensionless parameter successfully predicts drop impingement modes across multiple fluids. Results of this study will inform the design of spray impingement cooling systems for electronics applications where the ``spreading'' mode is preferred.

[Biomimetic mineralization of rod-like cellulose nano-whiskers and spectrum analysis].

PubMed

Qu, Ping; Wang, Xuan; Cui, Xiao-xia; Zhang, Li-ping

2012-05-01

Cellulose nano-whiskers/nano-hydroxyapatite composite was prepared with biomimetic mineralization using rod-like cellulose nano-whiskers as template. The cellulose nano-whiskers and cellulose nano-whiskers/nano-hydroxyapatite composite were characterized by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS) and scanning electron microscope-energy dispersive analysis of X-rays (SEM-EDXA). Variation and distribution of carbon, oxygen, calcium, and phosphorus in the composites were studied. The morphologies and growth mechanism of nano-hydroxyapatite were analyzed. The results showed that nano-hydroxyapatite was formed on the surface of cellulose nano-whiskers; the carbon-oxygen ratio of cellulose nano-whiskers and cellulose nano-whiskers/nano-hydroxyapatite composite was 1.81 and 1.54, respectively; the calcium-phosphorus ratio of the composite was 1.70. The nucleation of nano-hydroxyapatite was around the hydroxyl groups of cellulose nano-whiskers. It is suggested that there is coordination between the hydroxyl groups of cellulose nano-whiskers and calcium ions of nano-hydroxyapatite. The nano-hydroxyapatite can distribute in the matrix of cellulose nano-whiskers. From the atomic force microscope (AFM) images, we can see that the diameter of the spherical nano-hydroxyapatite particles was about 20 nm.

Method and Apparatus for Forming Nanodroplets

NASA Technical Reports Server (NTRS)

Ackley, Donald; Forster, Anita

2011-01-01

This innovation uses partially miscible fluids to form nano- and microdroplets in a microfluidic droplet generator system. Droplet generators fabricated in PDMS (polydimethylsiloxane) are currently being used to fabricate engineered nanoparticles and microparticles. These droplet generators were first demonstrated in a T-junction configuration, followed by a cross-flow configuration. All of these generating devices have used immiscible fluids, such as oil and water. This immiscible fluid system can produce mono-dispersed distributions of droplets and articles with sizes ranging from a few hundred nanometers to a few hundred microns. For applications such as drug delivery, the ability to encapsulate aqueous solutions of drugs within particles formed from the droplets is desirable. Of particular interest are non-polar solvents that can dissolve lipids for the formation of liposomes in the droplet generators. Such fluids include ether, cyclohexane, butanol, and ethyl acetate. Ethyl acetate is of particular interest for two reasons. It is relatively nontoxic and it is formed from ether and acetic acid, and maybe broken down into its constituents at relatively low concentrations.

Modeling the Influence of Injection Modes on the Evolution of Solution Sprays in a Plasma Jet

NASA Astrophysics Data System (ADS)

Shan, Y.; Coyle, T. W.; Mostaghimi, J.

2010-01-01

Solution precursor plasma spraying (SPPS) is a novel technology with great potential for depositing finely structured ceramic coatings with nano- and sub-micrometric features. The solution is injected into the plasma jet either as a liquid stream or gas atomized droplets. Solution droplets or the stream interact with the plasma jet and break up into fine droplets. The solvent vaporizes very fast as the droplets travel downstream. Solid particles are finally formed, and the particle are heated up and accelerated to the substrate to generate the coating. The deposition process and the properties of coatings obtained are extremely sensitive to the process parameters, such as torch operating conditions, injection modes, injection parameters, and substrate temperatures. This article numerically investigates the effect of injection modes, a liquid stream injection and a gas-blast injection, on the size distribution of injected droplets. The particle/droplet size, temperature, and position distributions on the substrate are predicted for different injection modes.

Bioeffects due to acoustic droplet vaporization

NASA Astrophysics Data System (ADS)

Bull, Joseph

2015-11-01

Encapsulated micro- and nano-droplets can be vaporized via ultrasound, a process termed acoustic droplet vaporization. Our interest is primarily motivated by a developmental gas embolotherapy technique for cancer treatment. In this methodology, infarction of tumors is induced by selectively formed vascular gas bubbles that arise from the acoustic vaporization of vascular microdroplets. Additionally, the microdroplets may be used as vehicles for localized drug delivery, with or without flow occlusion. In this talk, we examine the dynamics of acoustic droplet vaporization through experiments and theoretical/computational fluid mechanics models, and investigate the bioeffects of acoustic droplet vaporization on endothelial cells and in vivo. Early timescale vaporization events, including phase change, are directly visualized using ultra-high speed imaging, and the influence of acoustic parameters on droplet/bubble dynamics is discussed. Acoustic and fluid mechanics parameters affecting the severity of endothelial cell bioeffects are explored. These findings suggest parameter spaces for which bioeffects may be reduced or enhanced, depending on the objective of the therapy. This work was supported by NIH grant R01EB006476.

Ionic liquid-facilitated preparation of lignocellulosic composites

USDA-ARS?s Scientific Manuscript database

Lignocellulosic composites (LCs) were prepared by partially dissolving cotton along with steam exploded Aspen wood and burlap fabric reinforcements utilizing an ionic liquid (IL) solvent. Two methods of preparation were employed. In the first method, a controlled amount of IL was added to preassembl...

Inter-particle interaction dependent evaporation-induced assembly in contact-free micro-colloidal droplets

NASA Astrophysics Data System (ADS)

Sen, Debasis; Biswas, Priyanka; Melo, J. S.

2018-04-01

Evaporation-induced assembly of constituent particles in tiny dispersion droplet allows an efficient way to realize nano-structured micro-granules with potential for various applications. Morphology of the granules, obtained by such one-step dispersion to granular transformation, is decided by several physicochemical conditions. Here we demonstrate that the inter-particle interaction plays a crucial role in deciding the assembled morphology. Resultant granules are investigated by complementary techniques, Electron microscopy and small-angle scattering.

A novel coarsening mechanism of droplets in immiscible fluid mixtures

NASA Astrophysics Data System (ADS)

Shimizu, Ryotaro; Tanaka, Hajime

2015-06-01

In our daily lives, after shaking a salad dressing, we see the coarsening of oil droplets suspended in vinegar. Such a demixing process is observed everywhere in nature and also of technological importance. For a case of high droplet density, domain coarsening proceeds with inter-droplet collisions and the resulting coalescence. This phenomenon has been explained primarily by the so-called Brownian-coagulation mechanism: stochastic thermal forces exerted by molecules induce random motion of individual droplets, causing accidental collisions and subsequent interface-tension-driven coalescence. Contrary to this, here we demonstrate that the droplet motion is not random, but hydrodynamically driven by the composition Marangoni force due to an interfacial tension gradient produced in each droplet as a consequence of composition correlation among droplets. This alters our physical understanding of droplet coarsening in immiscible liquid mixtures on a fundamental level.

Lecithin-Based Nano-emulsification Improves the Bioavailability of Conjugated Linoleic Acid.

PubMed

Heo, Wan; Kim, Jun Ho; Pan, Jeong Hoon; Kim, Young Jun

2016-02-17

In this study, we investigated the effects of lecithin-based nano-emulsification on the heat stability and bioavailability of conjugated linoleic acid (CLA) in different free fatty acid (FFA) and triglyceride (TG) forms. CLA nano-emulsion in TG form exhibited a small droplet size (70-120 nm) compared to CLA nano-emulsion in FFA form (230-260 nm). Nano-emulsification protected CLA isomers in TG form, but not in free form, against thermal decomposition during the heat treatment. The in vitro bioavailability test using monolayers of Caco-2 human intestinal cells showed that nano-emulsification increased the cellular uptake of CLA in both FFA and TG forms. More importantly, a rat feeding study showed that CLA content in small intestinal tissues or plasma was higher when CLA was emulsified, indicating an enhanced oral bioavailability of CLA by nano-emulsification. These results provide important information for development of nano-emulsion-based delivery systems that improve thermal stability and bioavailability of CLA.

Phase Structures and Magnetic Properties of Graphite Nanosheets and Ni-Graphite Nanocomposite Synthesized by Electrical Explosion of Wire in Liquid

NASA Astrophysics Data System (ADS)

Nguyen, Minh-Thuyet; Kim, Jin-Hyung; Lee, Jung-Goo; Kim, Jin-Chun

2018-03-01

The present work studied on phases and magnetic properties of graphite nanosheets and Ni-graphite nanocomposite synthesized using the electrical explosion of wire (EEW) in ethanol. X-ray diffraction and field emission scanning electron microscope were used to investigate the phases and the morphology of the nanopowders obtained. It was found that graphite nanosheets were absolutely fabricated by EEW with a thickness of 29 nm and 3 μm diameter. The as-synthesized Ni-graphite composite powders had a Ni-coating on the surfaces of graphite sheets. The hysteresis loop of the as-exploded, the hydrogen-treated composite nanopowders and the sintered samples were examined with a vibrating sample magnetometer at room temperature. The Ni-graphite composite exposed the magnetic behaviors which are attributed to Ni component. The magnetic properties of composite had the improvement from 10.2 emu/g for the as-exploded powders to 15.8 emu/g for heat-treated powders and 49.16 emu/g for sintered samples.

Foraminiferal Metabolism Under Hypoxia: Sub-Cellular NanoSIMS Imaging of Intertidal Ammonia tepida Feeding Behavior

NASA Astrophysics Data System (ADS)

LeKieffre, C.; Spangenberg, J.; Geslin, E.; Meibom, A.

2016-02-01

Hypoxic events particularly affect benthic ecosystems on continental shelves and in coastal areas where renewal of bottom waters slow. Foraminifera living in such environments are among the most tolerant to hypoxia in the meiofauna. Some foraminifera species are able to survive hypoxia, and even anoxia, for weeks to months. Different species must have developed different mechanisms for survival - hypotheses include reduction of the metabolism, symbiosis with bacteria, or denitrification. NanoSIMS (Secondary Ion Mass Spectrometry) imaging is a powerful analytical technique to visualize and quantify the incorporation and transfer of isotopically labeled compounds in organisms with subcellular resolution. We used NanoSIMS imaging, correlated with TEM ultrastructural observations of individual foraminifera, to study the metabolism of intertidal Ammonia tepida, which has shown strongly reduced metabolism under anoxia. Individuals were fed with a 13C-labeled microalgal biofilm and incubated for 4 weeks in oxic and anoxic conditions, respectively. NanoSIMS imaging reveal strongly contrasting cellular-level dynamics of integration and transfer of the ingested biofilm components under the two conditions. In oxic conditions, ingested biofilm components are internalized, metabolized, and used for biosynthesis of different cellular components on a time scale of 24 hours: Lipid droplets are formed, then consumed through respiration. In contrast, upon the onset of anoxia, individual internalized biofilm components remain visible within the cytoplasm after 4 weeks. Lipids of different compositions are initially formed but then not respired. These observations indicate that foraminifera do initially have an active heterotrophic metabolism in the absence of oxygen, but this it is strongly reduced when oxygen is no longer available. Isotopic labeling experiments, NanoSIMS and TEM imaging, and GC-MS will be key to study metabolic mechanisms under anoxic conditions in marine environments.

Studies on the formation of polymeric nano-emulsions obtained via low-energy emulsification and their use as templates for drug delivery nanoparticle dispersions.

PubMed

Calderó, G; Montes, R; Llinàs, M; García-Celma, M J; Porras, M; Solans, C

2016-09-01

Ethylcellulose nanoparticles have been obtained from O/W nano-emulsions of the water/polyoxyethylene 10 oleyl ether/[ethyl acetate+4wt% ethylcellulose] system by low energy-energy emulsification at 25°C. Nano-emulsions with droplet sizes below 200nm and high kinetic stability were chosen for solubilising dexamethasone (DXM). Phase behaviour, conductivity and optical analysis studies of the system have evidenced for the first time that both, the polymer and the drug play a role on the structure of the aggregates formed along the emulsification path. Nano-emulsion formation may take place by both, phase inversion and self-emulsification. Spherical polymeric nanoparticles containing surfactant, showing sizes below 160nm have been obtained from the nano-emulsions by organic solvent evaporation. DXM loading in the nanoparticles was high (>90%). The release kinetics of nanoparticle dispersions with similar particle size and encapsulated DXM but different polymer to surfactant ratio were studied and compared to an aqueous DXM solution. Drug release from the nanoparticle dispersions was slower than from the aqueous solution. While the DXM solution showed a Fickian release pattern, the release behaviour from the nanoparticle dispersions was faster than that expected from a pure Fickian release. A coupled diffusion/relaxation model fitted the results very well, suggesting that polymer chains undergo conformational changes enhancing drug release. The contribution of diffusion and relaxation to drug transport in the nanoparticle dispersions depended on their composition and release time. Surfactant micelles present in the nanoparticle dispersion may exert a mild reservoir effect. The small particle size and the prolonged DXM release provided by the ethylcellulose nanoparticle dispersions make them suitable vehicles for controlled drug delivery applications. Copyright © 2016 Elsevier B.V. All rights reserved.

Multifunctional carbon nano-paper composite

NASA Astrophysics Data System (ADS)

Zhang, Zhichun; Chu, Hetao; Wang, Kuiwen; Liu, Yanjv; Leng, Jinsong

2013-08-01

Carbon Nanotube (CNT), for its excellent mechanical, electrical properties and nano size, large special surface physical property, become the most promising material. But carbon nanotube can still fabricated in micro dimension, and can't be made into macro size, so to the carbon nanotube filled composite can't explore the properties of the CNT. Carbon nano-paper is made of pure CNT, with micro pore, and it turn micro sized CNT into macro shaped membrane. Based on the piezo-resistivity and electrical conductivity of the carbon nano-paper, we used the carbon nano-paper as functional layers fabricate functional composite, and studies its strain sensing, composite material deicing and shape memory polymer (SMP) material electric actuation performance. The results shown that the resin can pregnant the nano paper, and there was good bond for nano paper and composite. The functional composite can monitoring the strain with high sensitivity comparing to foil strain gauge. The functional composite can be heated via the carbon nano paper with low power supply and high heating rate. The composite has good deicing and heat actuation performance to composite material. For the good strain sensing, electric conductivity and self-heating character of the carbon nano-paper composite, it can be used for self sensing, anti lightning strike and deicing of composite materials in aircrafts and wind turbine blades.

Improvement of mechanical and thermal properties of high energy electron beam irradiated HDPE/hydroxyapatite nano-composite

NASA Astrophysics Data System (ADS)

Mohammadi, M.; Ziaie, F.; Majdabadi, A.; Akhavan, A.; Shafaei, M.

2017-01-01

In this research work, the nano-composites of high density polyethylene/hydroxyapatite samples were manufactured via two methods: In the first method, the granules of high density polyethylene and nano-structure hydroxyapatite were processed in an internal mixer to prepare the nano-composite samples with a different weight percentage of the reinforcement phase. As for the second one, high density polyethylene was prepared in nano-powder form in boiling xylene. During this procedure, the hydroxyapatite nano-powder was added with different weight percentages to the solvent to obtain the nano-composite. In both of the procedures, the used hydroxyapatite nano-powder was synthesized via hydrolysis methods. The samples were irradiated under 10 MeV electron beam in 70-200 kGy of doses. Mechanical, thermal and morphological properties of the samples were investigated and compared. The results demonstrate that the nano-composites which we have prepared using nano-polyethylene, show better mechanical and thermal properties than the composites prepared from normal polyethylene granules, due to the better dispersion of nano-particles in the polymer matrix.

Composition measurements of binary mixture droplets by rainbow refractometry.

PubMed

Wilms, J; Weigand, B

2007-04-10

So far, refractive index measurements by rainbow refractometry have been used to determine the temperature of single droplets and ensembles of droplets. Rainbow refractometry is, for the first time, to the best of our knowledge, applied to measure composition histories of evaporating, binary mixture droplets. An evaluation method is presented that makes use of Airy theory and the simultaneous size measurement by Mie scattering imaging. The method further includes an empirical correction function for a certain diameter and refractive index range. The measurement uncertainty was investigated by numerical simulations with Lorenz-Mie theory. For the experiments, an optical levitation setup was used allowing for long measurement periods. Temperature measurements of single-component droplets at different temperature levels are shown to demonstrate the accuracy of rainbow refractometry. Measurements of size and composition histories of binary mixture droplets are presented for two different mixtures. Experimental results show good agreement with numerical results using a rapid-mixing model.

Mechanically modulated dewetting by atomic force microscope for micro- and nano- droplet array fabrication.

PubMed

Wang, Feifei; Li, Pan; Wang, Dong; Li, Longhai; Xie, Shuangxi; Liu, Lianqing; Wang, Yuechao; Li, Wen Jung

2014-10-06

Organizing a material into well-defined patterns during the dewetting process provides an attractive micro-/nano-fabrication method without using a conventional lithographic process, and hence, offers potential applications in organic electronics, optics systems, and memory devices. We report here how the mechanical modification of polymer surface by an Atomic Force Microscope (AFM) can be used to guide thin film dewetting evolution and break the intrinsic spatial correlation of spontaneous instability. An AFM is used to implement the mechanical modification of progressively narrow grids to investigate the influence of pattern size on the modulation of ultrathin polystyrene films dewetting evolution. For films with different initial thicknesses, when grid size is close to or below the characteristic wavelength of instability, the spinodal dewetting is suppressed, and film rupture is restricted to the cutting trench. We will show in this paper it is possible to generate only one droplet per gridded area on a thin film subsequent to nucleation dominated dewetting on a non-patterned substrate. Furthermore, when the grid periodicity exceeds the spinodal length, the number of droplets in predefined areas gradually approaches that associated with unconfined dewetting.

Mechanically Modulated Dewetting by Atomic Force Microscope for Micro- and Nano- Droplet Array Fabrication

PubMed Central

Wang, Feifei; Li, Pan; Wang, Dong; Li, Longhai; Xie, Shuangxi; Liu, Lianqing; Wang, Yuechao; Li, Wen Jung

2014-01-01

Organizing a material into well-defined patterns during the dewetting process provides an attractive micro-/nano-fabrication method without using a conventional lithographic process, and hence, offers potential applications in organic electronics, optics systems, and memory devices. We report here how the mechanical modification of polymer surface by an Atomic Force Microscope (AFM) can be used to guide thin film dewetting evolution and break the intrinsic spatial correlation of spontaneous instability. An AFM is used to implement the mechanical modification of progressively narrow grids to investigate the influence of pattern size on the modulation of ultrathin polystyrene films dewetting evolution. For films with different initial thicknesses, when grid size is close to or below the characteristic wavelength of instability, the spinodal dewetting is suppressed, and film rupture is restricted to the cutting trench. We will show in this paper it is possible to generate only one droplet per gridded area on a thin film subsequent to nucleation dominated dewetting on a non-patterned substrate. Furthermore, when the grid periodicity exceeds the spinodal length, the number of droplets in predefined areas gradually approaches that associated with unconfined dewetting. PMID:25283744

Modelling and investigation of partial wetting surfaces for drop dynamics using lattice Boltzmann method

NASA Astrophysics Data System (ADS)

Pravinraj, T.; Patrikar, Rajendra

2017-07-01

Partial wetting surfaces and its influence on the droplet movement of micro and nano scale being contemplated for many useful applications. The dynamics of the droplet usually analyzed with a multiphase lattice Boltzmann method (LBM). In this paper, the influence of partial wetting surface on the dynamics of droplet is systematically analyzed for various cases. Splitting of droplets due to chemical gradient of the surface is studied and analyses of splitting time for various widths of the strips for different Weber numbers are computed. With the proposed model one can tune the splitting volume and time by carefully choosing a strip width and droplet position. The droplet spreading on chemically heterogeneous surfaces shows that the spreading can be controlled not only by parameters of Weber number but also by tuning strip width ratio. The transportation of the droplet from hydrophobic surface to hydrophilic surface due to chemical gradient is simulated and analyzed using our hybrid thermodynamic-image processing technique. The results prove that with the progress of time the surface free energy decreases with increase in spreading area. Finally, the transportation of a droplet on microstructure gradient is demonstrated. The model explains the temporal behaviour of droplet during the spreading, recoiling and translation along with tracking of contact angle hysteresis phenomenon.

Eutectic Nano-Droplet Template Injection into Bulk Silicon to Construct Porous Frameworks with Concomitant Conformal Coating as Anodes for Li-Ion Batteries

PubMed Central

Qu, Fei; Li, Chilin; Wang, Zumin; Wen, Yuren; Richter, Gunther; Strunk, Horst P.

2015-01-01

Building porosity in monolithic materials is highly desired to design 3D electrodes, however ex-situ introduction or in-situ generation of nano-scale sacrificial template is still a great challenge. Here Al-Si eutectic droplet templates are uniformly injected into bulk Si through Al-induced solid-solid convection to construct a highly porous Si framework. This process is concomitant with process-inherent conformal coating of ion-conductive oxide. Such an all-in-one method has generated a (continuously processed) high-capacity Si anode integrating longevity and stable electrolyte-anode diaphragm for Li-ion batteries (e.g. a reversible capacity as large as ~1800 mAh/g or ~350 μAh/cm2-μm with a CE of ~99% at 0.1 C after long-term 400 cycles). PMID:25988370

Producing colloids with microfluidics

NASA Astrophysics Data System (ADS)

Pannacci, Nicolas; Willaime, Herve; Tabeling, Patrick

2008-11-01

Submicronic emulsions are commonly used in pharmaceutical, food, cosmetic and material industries. Standard microfluidic tool is particularly convenient to produce in a very controlled way either droplets of typical diameter ranging from 10 to 300 microns with a perfect monodispersity (<3%), or double emulsions as well as double droplets (janus). We report the use of microfluidic devices to produce submicronic objects. We use a hydrodynamic flow-focusing that has the advantage to generate nanodrops in a way that is slightly dependent on the fluids used. The control on such a flow authorizes the adjustment of the diameter of the colloids formed. We will show brownian particles from 860 nm to 1.3 μm in diameter obtained in such way and their clustering into crystals thanks to their high monodispersity. These first experimental results are very promising and make evident the great potential of micro and nano-fluidics to produce nano-emulsions or colloids with very controlled size that metamaterials can require.

Electro-suppression of water nano-droplets' solidification in no man's land: Electromagnetic fields' entropic trapping of supercooled water

NASA Astrophysics Data System (ADS)

Nandi, Prithwish K.; Burnham, Christian J.; English, Niall J.

2018-01-01

Understanding water solidification, especially in "No Man's Land" (NML) (150 K < T < 235 K) is crucially important (e.g., upper-troposphere cloud processes) and challenging. A rather neglected aspect of tropospheric ice-crystallite formation is inevitably present electromagnetic fields' role. Here, we employ non-equilibrium molecular dynamics of aggressively quenched supercooled water nano-droplets in the gas phase under NML conditions, in externally applied electromagnetic (e/m) fields, elucidating significant differences between effects of static and oscillating fields: although static fields induce "electro-freezing," e/m fields exhibit the contrary - solidification inhibition. This anti-freeze action extends not only to crystal-ice formation but also restricts amorphisation, i.e., suppression of low-density amorphous ice which forms otherwise in zero-field NML environments. E/m-field applications maintain water in the deeply supercooled state in an "entropic trap," which is ripe for industrial impacts in cryo-freezing, etc.

Eutectic nano-droplet template injection into bulk silicon to construct porous frameworks with concomitant conformal coating as anodes for Li-ion batteries.

PubMed

Qu, Fei; Li, Chilin; Wang, Zumin; Wen, Yuren; Richter, Gunther; Strunk, Horst P

2015-05-19

Building porosity in monolithic materials is highly desired to design 3D electrodes, however ex-situ introduction or in-situ generation of nano-scale sacrificial template is still a great challenge. Here Al-Si eutectic droplet templates are uniformly injected into bulk Si through Al-induced solid-solid convection to construct a highly porous Si framework. This process is concomitant with process-inherent conformal coating of ion-conductive oxide. Such an all-in-one method has generated a (continuously processed) high-capacity Si anode integrating longevity and stable electrolyte-anode diaphragm for Li-ion batteries (e.g. a reversible capacity as large as ~1800 mAh/g or ~350 μAh/cm(2)-μm with a CE of ~99% at 0.1 C after long-term 400 cycles).

Biochar-based nano-composites for the decontamination of wastewater: A review.

PubMed

Tan, Xiao-Fei; Liu, Yun-Guo; Gu, Yan-Ling; Xu, Yan; Zeng, Guang-Ming; Hu, Xin-Jiang; Liu, Shao-Bo; Wang, Xin; Liu, Si-Mian; Li, Jiang

2016-07-01

Synthesizing biochar-based nano-composites can obtain new composites and combine the advantages of biochar with nano-materials. The resulting composites usually exhibit great improvement in functional groups, pore properties, surface active sites, catalytic degradation ability and easy to separation. These composites have excellent abilities to adsorb a range of contaminants from aqueous solutions. Particularly, catalytic material-coated biochar can exert simultaneous adsorption and catalytic degradation function for organic contaminants removal. Synthesizing biochar-based nano-composites has become an important practice for expanding the environmental applications of biochar and nanotechnology. This paper aims to review and summarize the various synthesis techniques for biochar-based nano-composites and their effects on the decontamination of wastewater. The characteristic and advantages of existing synthesis methods are summarized and discussed. Application of biochar-based nano-composites for different contaminants removal and the underlying mechanisms are reviewed. Furthermore, knowledge gaps that exist in the fabrication and application of biochar-based nano-composites are also identified. Copyright © 2016 Elsevier Ltd. All rights reserved.

Preparation of Pickering emulsions stabilized by metal organic frameworks using oscillatory woven metal micro-screen.

PubMed

Sabouni, R; Gomaa, H G

2015-06-14

Uniform Pickering emulsions stabilized by metal organic frameworks (MOFs) MIL-101 and ZIF-8 nanoparticles (NPs) were successfully prepared using an oscillatory woven metal microscreen (WMMS) emulsification system in the presence and the absence of surfactants. The effects of operating and system parameters including the frequency and amplitude of oscillation, the type of nano-particle and/or surfactant on the droplet size and coefficient of variance of the prepared emulsions are investigated. The results showed that both the hydrodynamics of the system and the hydrophobic/hydrophilic nature of the NP influenced the interfacial properties of the oil-water interface during droplet formation and after detachment, which in turn affected the final droplet size and distribution. Comparison between the measured and predicted droplet size using a simple torque balance (TB) model is discussed.

Close-packed monolayer self-assembly of silica nanospheres assisted by infrared irradiation

NASA Astrophysics Data System (ADS)

Minh, Nguyen Van; Hue, Nguyen Thi; Lien, Nghiem Thi Ha; Hoang, Chu Manh

2018-01-01

In this paper, we report on a fast and cost-effective drop coating technique for the self-assembly of silica nano-spheres from a mono-dispersed colloidal suspension into close-packed monolayer (CMP) on hydrophilic single-crystal silicon substrate. The technique includes the self-assembly of silica nano-spheres on slanted silicon substrate and infrared irradiation during evaporation process of the coated droplet. The influence of the substrate slant angle and infrared irradiation on the formation of silica nano-sphere monolayer is investigated. This achievement is promising for various applications, such as a mask layer for nano-sphere lithography that is employed for producing fundamental elements in photonics, plasmonics, and solar cell. [Figure not available: see fulltext.

Interdroplet bilayer arrays in millifluidic droplet traps from 3D-printed moulds.

PubMed

King, Philip H; Jones, Gareth; Morgan, Hywel; de Planque, Maurits R R; Zauner, Klaus-Peter

2014-02-21

In droplet microfluidics, aqueous droplets are typically separated by an oil phase to ensure containment of molecules in individual droplets of nano-to-picoliter volume. An interesting variation of this method involves bringing two phospholipid-coated droplets into contact to form a lipid bilayer in-between the droplets. These interdroplet bilayers, created by manual pipetting of microliter droplets, have proved advantageous for the study of membrane transport phenomena, including ion channel electrophysiology. In this study, we adapted the droplet microfluidics methodology to achieve automated formation of interdroplet lipid bilayer arrays. We developed a 'millifluidic' chip for microliter droplet generation and droplet packing, which is cast from a 3D-printed mould. Droplets of 0.7-6.0 μL volume were packed as homogeneous or heterogeneous linear arrays of 2-9 droplets that were stable for at least six hours. The interdroplet bilayers had an area of up to 0.56 mm(2), or an equivalent diameter of up to 850 μm, as determined from capacitance measurements. We observed osmotic water transfer over the bilayers as well as sequential bilayer lysis by the pore-forming toxin melittin. These millifluidic interdroplet bilayer arrays combine the ease of electrical and optical access of manually pipetted microdroplets with the automation and reproducibility of microfluidic technologies. Moreover, the 3D-printing based fabrication strategy enables the rapid implementation of alternative channel geometries, e.g. branched arrays, with a design-to-device time of just 24-48 hours.

Application of nano-TiO2/LDPE composite film on photocatalytic oxidation degradation of dichloromethane.

PubMed

Suwannahong, Kowit; Liengcharernsit, Winai; Sanongraj, Wipada; Kruenate, Jittiporn

2012-09-01

This study focused on the photocatalytic destruction of dichloromethane (DCM) in indoor air using the nano-TiO2/LDPE composite film as an economical photocatalyst. The nano-TiO2 was dispersed in a polyethylene matrix to form composite film. The photocatalytic activity of the nano-TiO2/LDPE composite films was evaluated through the degradation of dichloromethane(DCM) under UV-C irradiance at specific wavelength of 254 nm. The percentage of nano-TiO2 contents varied from 0, 5, and 10% (wt cat./wt LDPE composite film). The results derived from the kinetic model revealed that the photocatalytic rates of 5 and 10 wt.% nano-TiO2/ LDPE composite films follow the first order reaction while the rate of the film without TiO2 followed the zero order reaction. At low concentration of DCM, the rate of photocatalytic degradation of the DCM was slower than that at high DCM concentration. The 10 wt.% of TiO2 content of the nano-TiO2/LDPE composite film yielded the highest degradation efficiency of 78%, followed by the removal efficiency of 55% for the 5 wt.% of TiO2 content of the nano-TiO2/LDPE composite film. In contrast with the composite film containing nano-TiO2, the LDPE film without adding nano-TiO2 expressed the degradation efficiency of 28%.

Nano-Fiber Reinforced Enhancements in Composite Polymer Matrices

NASA Technical Reports Server (NTRS)

Chamis, Christos C.

2009-01-01

Nano-fibers are used to reinforce polymer matrices to enhance the matrix dependent properties that are subsequently used in conventional structural composites. A quasi isotropic configuration is used in arranging like nano-fibers through the thickness to ascertain equiaxial enhanced matrix behavior. The nano-fiber volume ratios are used to obtain the enhanced matrix strength properties for 0.01,0.03, and 0.05 nano-fiber volume rates. These enhanced nano-fiber matrices are used with conventional fiber volume ratios of 0.3 and 0.5 to obtain the composite properties. Results show that nano-fiber enhanced matrices of higher than 0.3 nano-fiber volume ratio are degrading the composite properties.

Mechanical and Morphological Study of Synthesized PMMA/CaCO3 Nano composites

NASA Astrophysics Data System (ADS)

Alam Md., Azad; Arif, Sajjad; Ansari, Akhter H.

2017-08-01

In this study, Nano-composites have been synthesized in which PMMA is the matrix material and calcium carbonate nanoparticles as the filler by In-situ polymerization reaction. Nano-CaCO3 added during polymerization and the quantity of nano-CaCO3 varied as 0.2, 0.4 and 0.6 wt. % of monomer quantity. The Nano-composites were prepared at three distinct stirring speeds 600, 800, 1000 rpm in order to observe the property with respect to stirring speeds. XRD gram depicts that the presence of nano-CaCO3 has given crystalline nature to Nano-composites. The effects of different concentrations of nano-CaCO3 loading on PMMA morphology were studied by using scanning electron microscope (SEM). The mechanical property is increasing with the stirring speed and concentration. Relative to neat PMMA a 62% increase in impact strength were observed in PMMA based Nano-composites using 0.6 wt.% nano-CaCO3.

Microfluidic control of droplet formation from stable emulsions formed by aqueous two-phase systems

NASA Astrophysics Data System (ADS)

Teixeira, Alyne G.; Tsai, Meng-Chiao; Frampton, John P.

2018-02-01

Aqueous two-phase systems (ATPSs) form from the thermodynamic separation of two dissolved incompatible solutes, such as two polymers, a polymer and a salt, and a polymer and a surfactant. At most supercritical concentrations, ATPS emulsions can be formed by vigorous mixing. These emulsions typically settle into distinct layers in minutes to hours. However, it is also possible to choose ATPS compositions with extremely long settling times that resemble stable emulsions. Here, we generated stable emulsions from a polyethylene glycol (PEG)-dextran ATPS by selecting ATPS compositions at the extreme ends of the tie lines connecting the binodal curve delineating phase-separating compositions. Droplets of PEG in a continuous dextran phase did not coalesce appreciably over the course of several days when stored in a conical tube or syringe. However, upon exposure to laminar flow conditions in a microfluidic channel, droplets were observed to coalesce. Through microscopic characterization of droplet volume, an increase in droplet size and decrease in overall droplet number was observed as a function of channel distance, suggesting a progressive droplet merging phenomenon. This novel approach to control droplet size by encouraging coalescence of stable emulsions under laminar flow in a microfluidic channel enables the production of droplets ranging from fL to several pL, which may enable various future biotechnology applications.

Conceptual Design Studies of Composite AMST

DTIC Science & Technology

1974-10-01

WEIGHT OF THE AIRFRAME THE PROPERTIES OF HIGH -STRENGTH GRAPHITE-EPOXY COMPOSITES (REPRESENTATIVE OF THORNEL 300 FIBERS) WERE USED IN THE APPLICATION...The primary advanced composite material selected was a high -strength graphite-epoxy (Thornel 300/Narmco 5208). Boron-infiltrated aluminum extrusions...Figure Page 25 Trimming Irregular Cutouts in Wing Box Attach Angles ...... 71 26 Hydroforming W-Truss Web Beaded Panels ................ 72 27 Exploded

Ice nucleation rates near ˜225 K

NASA Astrophysics Data System (ADS)

Amaya, Andrew J.; Wyslouzil, Barbara E.

2018-02-01

We have measured the ice nucleation rates, Jice, in supercooled nano-droplets with radii ranging from 6.6 nm to 10 nm and droplet temperatures, Td, ranging from 225 K to 204 K. The initial temperature of the 10 nm water droplets is ˜250 K, i.e., well above the homogeneous nucleation temperature for micron sized water droplets, TH ˜235 K. The nucleation rates increase systematically from ˜1021 cm-3 s-1 to ˜1022 cm-3 s-1 in this temperature range, overlap with the nucleation rates of Manka et al. [Phys. Chem. Chem. Phys. 14, 4505 (2012)], and suggest that experiments with larger droplets would extrapolate smoothly the rates of Hagen et al. [J. Atmos. Sci. 38, 1236 (1981)]. The sharp corner in the rate data as temperature drops is, however, difficult to match with available theory even if we correct classical nucleation theory and the physical properties of water for the high internal pressure of the nanodroplets.

Efficiency of emulsifier-free emulsions and emulsions containing rapeseed lecithin as delivery systems for vectorization and release of coenzyme Q10: physico-chemical properties and in vitro evaluation.

PubMed

Kaci, M; Arab-Tehrany, E; Dostert, G; Desjardins, I; Velot, E; Desobry, S

2016-11-01

To improve the encapsulation and release of coenzyme Q10 (CoQ10), emulsifier-free-emulsions were developed with a new emulsification process using high-frequency ultrasound (HFU) at 1.7MHz. Nano-emulsions containing CoQ10 were prepared with or without rapeseed lecithin as an emulsifier. The emulsions prepared with HFU were compared with an emulsion of CoQ10 containing emulsifier prepared with the same emulsification technique as well as with emulsions prepared with low-frequency ultrasound coupled with high-pressure homogenization (LFU+HPH). The physico-chemical properties of the emulsions were determined by average droplet size measurement with nano-droplet tracking analysis, droplet surface charge with ζ potential measurement, surface tension and rheological behaviour. Emulsions made by LFU+HPH with an emulsifier showed lower droplet sizes due to cavitation generated by the HFU process. Surface tension results showed that there was no significant difference between emulsions containing lecithin emulsifier regardless of the preparation process or the inclusion of CoQ10. In vitro biocompatibility tests were performed on human mesenchymal stem cells in order to show the cytotoxicity of various formulations and the efficiency of CoQ10-loaded emulsions. In vitro tests proved that the vectors were not toxic. Furthermore, CoQ10 facilitated a high rate of cell proliferation and metabolic activity especially when in an emulsifier-free formulation. Copyright © 2016 Elsevier B.V. All rights reserved.

Porous block nanofiber composite filters

DOEpatents

Ginley, David S.; Curtis, Calvin J.; Miedaner, Alexander; Weiss, Alan J.; Paddock, Arnold

2016-08-09

Porous block nano-fiber composite (110), a filtration system (10) and methods of using the same are disclosed. An exemplary porous block nano-fiber composite (110) includes a porous block (100) having one or more pores (200). The porous block nano-fiber composite (110) also includes a plurality of inorganic nano-fibers (211) formed within at least one of the pores (200).

Tribological behavior of Al-WC nano-composites fabricated by ultrasonic cavitation assisted stir-cast method

NASA Astrophysics Data System (ADS)

Pal, Arpan; Poria, Suswagata; Sutradhar, Goutam; Sahoo, Prasanta

2018-03-01

In the present study, the effects of WC nano-particles content on the microstructure, hardness, wear, and friction behavior of aluminum matrix composites are investigated. Al-WC nano composites with varying wt% of WC (0, 1, 1.5, and 2) are fabricated using ultrasonic cavitation assisted stir-cast method. The microstructure of the nano-composite samples is analyzed using optical microscopy and scanning electron microscopy. Elemental composition is determined by energy dispersive x-ray analysis. Vicker’s microhardness test is performed in different locations on the composite sample surface with a load of 50 gf and 10s dwell time. Wear and friction of the composites under dry sliding is studied using a pin-on-disk tribotester for varying normal load (10–40 N) and sliding speed (0.1–0.4 m/s). Uniform distribution of nano-WC is observed over composite surface without noticeable clustering. Reinforcement of nano-WC particles improves wear resistance and frictional behavior of the composite. Hardness is seen to increase with increase in wt% of nano-particles. Wear behavior of composites depends on formation of layers over the surface mixed with oxidized debris and counter-face particles. Wear mechanism changes from adhesion to abrasion with increase in wt% of hard nano particles.

Chemical consequences of the initial diffusional growth of cloud droplets - A clean marine case

NASA Technical Reports Server (NTRS)

Twohy, C. H.; Charlson, R. J.; Austin, P. H.

1989-01-01

A simple microphysical cloud parcel model and a simple representation of the background marine aerosol are used to predict the concentrations and compositions of droplets of various sizes near cloud base. The aerosol consists of an externally-mixed ammonium bisulfate accumulation mode and a sea-salt coarse particle mode. The difference in diffusional growth rates between the small and large droplets as well as the differences in composition between the two aerosol modes result in substantial differences in solute concentration and composition with size of droplets in the parcel. The chemistry of individual droplets is not, in general, representative of the bulk (volume-weighted mean) cloud water sample. These differences, calculated to occur early in the parcel's lifetime, should have important consequences for chemical reactions such as aqueous phase sulfate production.

Effects of SiO2 nano-particles on tribological and mechanical properties of aluminum matrix composites by different dispersion methods

NASA Astrophysics Data System (ADS)

Azadi, Mahboobeh; Zolfaghari, Mehrdad; Rezanezhad, Saeid; Azadi, Mohammad

2018-05-01

This study has been presented with mechanical properties of aluminum matrix composites, reinforced by SiO2 nano-particles. The stir casting method was employed to produce various aluminum matrix composites. Different composites by varying the SiO2 nano-particle content (including 0.5 and 1 weight percents) and two dispersion methods (including ball-milling and pre-heating) were made. Then, the density, the hardness, the compression strength, the wear resistance and the microstructure of nano-composites have been studied in this research. Besides, the distribution of nano-particles in the aluminum matrix for all composites has been also evaluated by the field emission scanning electron microscopy (FESEM). Obtained results showed that the density, the elongation and the ultimate compressive strength of various nano-composites decreased by the presence of SiO2 nano-particles; however, the hardness, the wear resistance, the yield strength and the elastic modulus of composites increased by auditioning of nano-particles to the aluminum alloy. FESEM images indicated better wetting of the SiO2 reinforcement in the aluminum matrix, prepared by the pre-heating dispersion method, comparing to ball-milling. When SiO2 nano-particles were added to the aluminum alloy, the morphology of the Si phase and intermetallic phases changed, which enhanced mechanical properties. In addition, the wear mechanism plus the friction coefficient value were changed for various nano-composites with respect to the aluminum alloy.

Composition measurements of binary mixture droplets by rainbow refractometry

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

Wilms, J.; Weigand, B

2007-04-10

So far, refractive index measurements by rainbow refractometry have been used to determine the temperature of single droplets and ensembles of droplets. Rainbow refractometry is, for the first time, to the best of our knowledge, applied to measure composition histories of evaporating, binary mixture droplets. An evaluation method is presented that makes use of Airy theory and the simultaneous size measurement by Mie scattering imaging. The method further includes an empirical correction function for a certain diameter and refractive index range. The measurement uncertainty was investigated by numerical simulations with Lorenz-Mie theory. For the experiments, an optical levitation setup wasmore » used allowing for long measurement periods. Temperature measurements of single-component droplets at different temperature levels are shown to demonstrate the accuracy of rainbow refractometry. Measurements of size and composition histories of binary mixture droplets are presented for two different mixtures. Experimental results show good agreement with numerical results using a rapid-mixing model.« less

Lipidomic and proteomic analysis of Caenorhabditis elegans lipid droplets and identification of ACS-4 as a lipid droplet-associated protein

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

Vrablik, Tracy L.; Petyuk, Vladislav A.; Larson, Emily M.

2015-06-27

Lipid droplets are cytoplasmic organelles that store neutral lipids for membrane synthesis and energy reserves. In this study, we characterized the lipid and protein composition of purified C. elegans lipid droplets. These lipid droplets are composed mainly of triacylglycerols, surrounded by a phospholipid monolayer composed primarily of phosphatidylcholine and phosphatidylethanolamine. The fatty acid composition of the triacylglycerols was rich in fatty acid species obtained from the dietary E. coli, including cyclopropane fatty acids and cis-vaccenic acid. Unlike other organisms, C. elegans lipid droplets contain very little cholesterol or cholesterol esters. Comparison of the lipid droplet proteomes of wild type andmore » high-fat daf-2 mutant strains shows a relative decrease of MDT-28 abundance in lipid droplets isolated from daf-2 mutants. Functional analysis of lipid droplet proteins identified in our proteomic studies indicated an enrichment of proteins required for growth and fat homeostasis in C. elegans.« less

Atomic-level study on mechanical properties and strengthening mechanisms of Al/SiC nano-composites

NASA Astrophysics Data System (ADS)

Huo, Shiyan; Xie, Lijing; Xiang, Junfeng; Pang, Siqin; Hu, Fang; Umer, Usama

2018-02-01

Molecular dynamics (MD) models for the study on the mechanical properties of β-SiC particles-reinforced aluminum matrix nano-composites (Al/SiC nano-composites) are established. The nano-composites in the model are fabricated by a powder metallurgy (P/M) process, followed by a hot isostatic pressing and then annealing to room temperature. The fabricated nano-composites have dense and even distributions of reinforced particles. Then representative volume elements (RVEs) of the fabricated nano-composites are built by adding periodic boundary conditions (PBCs). In this way, RVEs with different volume fractions and particle sizes of SiC are produced and put into the simulation of tension tests. The elasticity and strength in single axial tension obtained from MD analysis are in good agreement with those calculated according to the rule of mixture. It is found that the dispersion of SiC particles into the Al matrix leads to a significant enhancement in the strength of nano-composites compared to pure Al, which is also dramatically affected by both the volume fraction and particle size. Additionally, the Al/SiC nano-composites with finer SiC particles get greater enhancement in the mechanical behavior than those with coarser ones. MD analysis clearly shows the contributions of load-transfer effect, thermal mismatch strengthening and Orowan strengthening to the strengthening of Al/SiC nano-composites.

Mechanical characterization of scalable cellulose nano-fiber based composites made using liquid composite molding process

Treesearch

Bamdad Barari; Thomas K. Ellingham; Issam I. Ghamhia; Krishna M. Pillai; Rani El-Hajjar; Lih-Sheng Turng; Ronald Sabo

2016-01-01

Plant derived cellulose nano-fibers (CNF) are a material with remarkable mechanical properties compared to other natural fibers. However, efforts to produce nano-composites on a large scale using CNF have yet to be investigated. In this study, scalable CNF nano-composites were made from isotropically porous CNF preforms using a freeze drying process. An improvised...

Fabrication of micro/nano-structures by electrohydrodynamic jet technique

NASA Astrophysics Data System (ADS)

Wang, Dazhi; Zhao, Xiaojun; Lin, Yigao; Ren, Tongqun; Liang, Junsheng; Liu, Chong; Wang, Liding

2017-12-01

Electrohydrodynamic jet (E-Jet) is an approach to the fabrication of micro/nano-structures by the use of electrical forces. In this process, the liquid is subjected to electrical and mechanical forces to form a liquid jet, which is further disintegrated into droplets. The major advantage of the E-Jet technique is that the sizes of the jet formed can be at the nanoscale far smaller than the nozzle size, which can realize high printing resolution with less risk of nozzle blockage. The E-Jet technique, which mainly includes E-Jet deposition and E-Jet printing, has a wide range of applications in the fabrication of micro/nano-structures for micro/nano-electromechanical system devices. This technique is also considered a micro/nano-fabrication method with a great potential for commercial use. This study mainly reviews the E-Jet deposition/printing fundamentals, fabrication process, and applications.

Changes in composition of spider orb web sticky droplets with starvation and web removal, and synthesis of sticky droplet compounds

PubMed Central

Townley, Mark A.; Tillinghast, Edward K.; Neefus, Christopher D.

2006-01-01

Summary The sticky spiral of araneoid spider orb webs consists of silk fibers coated with adhesive droplets. The droplets contain a variety of low-molecular-mass compounds (LMM). Within a species, a fairly consistent ratio of LMM is often observed, but substantial variability can exist. To gain insight into factors influencing LMM composition, spiders of three araneid species were starved and LMM from their webs were analyzed for changes in composition. To determine if these changes were consistent with the spider’s ability to synthesize the different organic LMM, synthetic capacities were estimated following the feeding of radiolabeled metabolites. Some changes in droplet composition were broadly consistent with differing synthetic capacities: molar percentages of less readily synthesized compounds (e.g., choline, isethionate, n-acetyltaurine) typically declined with starvation, at least during a portion of the imposed fast, while more readily synthesized compounds (e.g., GABamide, glycine) tended to increase. Most striking was the apparent partial substitution of n-acetylputrescine by the more readily synthesized GABamide in fasting Argiope trifasciata. However, departures from expected compositional shifts demonstrated that synthetic capacity alone does not adequately predict sticky droplet compositional shifts with starvation. Moreover, feeding controls exhibited some changes in composition similar to starving spiders. As the webs of both feeding and starving spiders were removed for chemical analysis and could not be recycled, the loss of LMM contained in these webs likely contributed to similarities between treatments. In addition, feeding spiders molted, oviposited, and/or built heavier webs. The added metabolic demands of these activities may have contributed to changes in composition similar to those resulting from starvation. PMID:16574806

Changes in composition of spider orb web sticky droplets with starvation and web removal, and synthesis of sticky droplet compounds.

PubMed

Townley, Mark A; Tillinghast, Edward K; Neefus, Christopher D

2006-04-01

The sticky spiral of araneoid spider orb webs consists of silk fibers coated with adhesive droplets. The droplets contain a variety of low-molecular-mass compounds (LMM). Within a species, a fairly consistent ratio of LMM is often observed, but substantial variability can exist. To gain insight into factors influencing LMM composition, spiders of three araneid species were starved and LMM from their webs were analyzed for changes in composition. To determine if these changes were consistent with the spider's ability to synthesize the different organic LMM, synthetic capacities were estimated following the feeding of radiolabeled metabolites. Some changes in droplet composition were broadly consistent with differing synthetic capacities: molar percentages of less readily synthesized compounds (e.g. choline, isethionate, N-acetyltaurine) typically declined with starvation, at least during a portion of the imposed fast, while more readily synthesized compounds (e.g. GABamide, glycine) tended to increase. Most striking was the apparent partial substitution of N-acetylputrescine by the more readily synthesized GABamide in fasting Argiope trifasciata. However, departures from expected compositional shifts demonstrated that synthetic capacity alone does not adequately predict sticky droplet compositional shifts with starvation. Moreover, feeding controls exhibited some changes in composition similar to starving spiders. As the webs of both feeding and starving spiders were removed for chemical analysis and could not be recycled, the loss of LMM contained in these webs likely contributed to similarities between treatments. In addition, feeding spiders molted, oviposited and/or built heavier webs. The added metabolic demands of these activities may have contributed to changes in composition similar to those resulting from starvation.

Flame Retardant Effect of Nano Fillers on Polydimethylsiloxane Composites.

PubMed

Jagdale, Pravin; Salimpour, Samera; Islam, Md Hujjatul; Cuttica, Fabio; Hernandez, Francisco C Robles; Tagliaferro, Alberto; Frache, Alberto

2018-02-01

Polydimethylsiloxane has exceptional fire retardancy characteristics, which make it a popular polymer in flame retardancy applications. Flame retardancy of polydimethylsiloxane with different nano fillers was studied. Polydimethylsiloxane composite fire property varies because of the shape, size, density, and chemical nature of nano fillers. In house made carbon and bismuth oxide nano fillers were used in polydimethylsiloxane composite. Carbon from biochar (carbonised bamboo) and a carbon by-product (carbon soot) were selected. For comparative study of nano fillers, standard commercial multiwall carbon nano tubes (functionalised, graphitised and pristine) as nano fillers were selected. Nano fillers in polydimethylsiloxane positively affects their fire retardant properties such as total smoke release, peak heat release rate, and time to ignition. Charring and surface ceramization are the main reasons for such improvement. Nano fillers in polydimethylsiloxane may affect the thermal mobility of polymer chains, which can directly affect the time to ignition. The study concludes that the addition of pristine multiwall carbon nano tubes and bismuth oxide nano particles as filler in polydimethylsiloxane composite improves the fire retardant property.

Meteorological and Aerosol effects on Marine Cloud Microphysical Properties

NASA Astrophysics Data System (ADS)

Sanchez, K. J.; Russell, L. M.; Modini, R. L.; Frossard, A. A.; Ahlm, L.; Roberts, G.; Hawkins, L. N.; Schroder, J. C.; Wang, Z.; Lee, A.; Abbatt, J.; Lin, J.; Nenes, A.; Wonaschuetz, A.; Sorooshian, A.; Noone, K.; Jonsson, H.; Albrecht, B. A.; Desiree, T. S.; Macdonald, A. M.; Seinfeld, J.; Zhao, R.

2015-12-01

Both meteorology and microphysics affect cloud formation and consequently their droplet distributions and shortwave reflectance. The Eastern Pacific Emitted Aerosol Cloud Experiment (EPEACE) and the Stratocumulus Observations of Los-Angeles Emissions Derived Aerosol-Droplets (SOLEDAD) studies provide detailed measurements in 6 case studies of both cloud thermodynamic properties and initial particle number distribution and composition, as well as the resulting cloud drop distribution and composition. This study uses simulations of a detailed chemical and microphysical aerosol-cloud parcel (ACP) model with explicit kinetic drop activation to reproduce the observed cloud droplet distribution and composition. Four of the cases examined had a sub-adiabatic lapse rate, which was shown to have fewer droplets due to decreased maximum supersaturation, lower LWC and higher cloud base height, consistent with previous findings. These detailed case studies provided measured thermodynamics and microphysics that constrained the simulated droplet size distribution sufficiently to match the droplet number within 6% and the size within 19% for 4 of the 6 cases, demonstrating "closure" or consistency of the measured composition with the measured CCN spectra and the inferred and modeled supersaturation. The contribution of organic components to droplet formation shows small effects on the droplet number and size in the 4 marine cases that had background aerosol conditions with varying amounts of coastal, ship or other non-biogenic sources. In contrast, the organic fraction and hygroscopicity increased the droplet number and size in the cases with generated smoke and cargo ship plumes that were freshly emitted and not yet internally mixed with the background particles. The simulation results show organic hygroscopicity causes small effects on cloud reflectivity (<0.7%) with the exception of the cargo ship plume and smoke plume which increased absolute cloud reflectivity fraction by 0.02 and 0.20 respectively. In addition, the ACP model simulations are compared to those from a numerical parameterization of cloud droplet activation that is suitable for GCMs and show droplet concentrations are comparable between the two methods.

Evolution of temperature of a droplet of liquid composite fuel interacting with heated airflow

NASA Astrophysics Data System (ADS)

Glushkov, D. O.; Zakharevich, A. V.; Strizhak, P. A.; Syrodoy, S. V.

2016-11-01

The macroscopic patterns of a temperature change at the center of a droplet of three-component (coal, water, petroleum) composite liquid fuel (CLF) were studied using a low-inertia thermoelectric converter and system of high-speed (up to 105 frames per second) video recording during the induction period at different heating intensity by the air flow with variable parameters: temperature of 670-870 K and motion velocity of 1-4 m/s. The studies were carried out for two groups of CLF compositions: fuel based on brown coal and coal cleaning rejects (filter cake). To assess the effect of liquid combustible component of CLF on characteristics of the ignition process, the corresponding composition of two-component coal-water fuel (CWF) was studied. The stages of inert heating of CLF and CWF droplets with characteristic size corresponding to radius of 0.75-1.5 mm, evaporation of moisture and liquid oil (for CLF), thermal decomposition of the organic part of coal, gas mixture ignition, and carbon burnout were identified. Regularities of changes in the temperature of CLF and CWF droplets at each of identified stages were identified for the cooccurrence of phase transitions and chemical reactions. Comparative analysis of the times of ignition delay and complete combustion of the droplets of examined fuel compositions was performed with varying droplet dimensions, temperatures, and oxidant flow velocity.

Dance of the Light Echoes

NASA Image and Video Library

2008-05-29

This composite image from NASA Spitzer Space Telescope shows the remnant of a star that exploded, called Cassiopeia A center and its surrounding light echoes -- dances of light through dusty clouds, created when stars blast apart.

Mathematical tool from corn stover TGA to determine its composition.

PubMed

Freda, Cesare; Zimbardi, Francesco; Nanna, Francesco; Viola, Egidio

2012-08-01

Corn stover was treated by steam explosion process at four different temperatures. A fraction of the four exploded matters was extracted by water. The eight samples (four from steam explosion and four from water extraction of exploded matters) were analysed by wet chemical way to quantify the amount of cellulose, hemicellulose and lignin. Thermogravimetric analysis in air atmosphere was executed on the eight samples. A mathematical tool was developed, using TGA data, to determine the composition of corn stover in terms of cellulose, hemicellulose and lignin. It uses the biomass degradation temperature as multiple linear function of the cellulose, hemicellulose and lignin content of the biomass with interactive terms. The mathematical tool predicted cellulose, hemicellulose and lignin contents with average absolute errors of 1.69, 5.59 and 0.74 %, respectively, compared to the wet chemical method.

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.

Transparent Oxyfluoride Nano-Glass-Ceramics Doped with Pr3+ and Pr3+-Yb3+ for NIR Emission

NASA Astrophysics Data System (ADS)

Gorni, Giulio; Cosci, Alessandro; Pelli, Stefano; Pascual, Laura; Durán, Alicia; Pascual, M. J.

2016-12-01

Pr3+-Yb3+ co-doped oxyfluoride glasses and glass-ceramics (GC) containing LaF3 nanocrystals have been prepared to obtain NIR emission of Yb3+ ions upon Pr3+ excitation in the blue region of the visible spectrum. Two different compositions have been tested 0.1-0.5 Pr-Yb and 0.5-1 Pr-Yb, in addition to Pr3+ singly doped samples. The crystallization mechanism of the nano-glass-ceramics was studied by DTA revealing that it occurs from a constant number of nuclei, the crystal growth being limited by diffusion. HR-TEM demonstrated that phase separation acts as precursor for LaF3 crystallization and a detailed analysis of the chemical composition (EDXS) revealed the enrichment in RE3+ ions inside the initial phase separated droplets, from which the LaF3 crystals are formed. The RE3+ ions incorporation inside LaF3 crystals was also proved by photoluminescence measurements showing Stark splitting of the RE3+ ions energy levels in the glass-ceramic samples. Lifetimes measurements showed the existence of a better energy transfer process between Pr3+ and Yb3+ ions in the glass-ceramics compared to the as made glass, and the highest value of energy transfer efficiency is 59% and the highest theoretical quantum efficiency is 159%, obtained for glass-ceramics GC0.1-0.5 Pr-Yb treated at 620 ºC-40 h.

A Novel Approach of Using Ground CNTs as the Carbon Source to Fabricate Uniformly Distributed Nano-Sized TiCx/2009Al Composites.

PubMed

Wang, Lei; Qiu, Feng; Ouyang, Licheng; Wang, Huiyuan; Zha, Min; Shu, Shili; Zhao, Qinglong; Jiang, Qichuan

2015-12-17

Nano-sized TiC x /2009Al composites (with 5, 7, and 9 vol% TiC x ) were fabricated via the combustion synthesis of the 2009Al-Ti-CNTs system combined with vacuum hot pressing followed by hot extrusion. In the present study, CNTs were used as the carbon source to synthesize nano-sized TiC x particles. An attempt was made to correlate the effect of ground CNTs by milling and the distribution of synthesized nano-sized TiC x particles in 2009Al as well as the tensile properties of nano-sized TiC x /2009Al composites. Microstructure analysis showed that when ground CNTs were used, the synthesized nano-sized TiC x particles dispersed more uniformly in the 2009Al matrix. Moreover, when 2 h-milled CNTs were used, the 5, 7, and 9 vol% nano-sized TiC x /2009Al composites had the highest tensile properties, especially, the 9 vol% nano-sized TiC x /2009Al composites. The results offered a new approach to improve the distribution of in situ nano-sized TiC x particles and tensile properties of composites.

A Novel Approach of Using Ground CNTs as the Carbon Source to Fabricate Uniformly Distributed Nano-Sized TiCx/2009Al Composites

PubMed Central

Wang, Lei; Qiu, Feng; Ouyang, Licheng; Wang, Huiyuan; Zha, Min; Shu, Shili; Zhao, Qinglong; Jiang, Qichuan

2015-01-01

Nano-sized TiCx/2009Al composites (with 5, 7, and 9 vol% TiCx) were fabricated via the combustion synthesis of the 2009Al-Ti-CNTs system combined with vacuum hot pressing followed by hot extrusion. In the present study, CNTs were used as the carbon source to synthesize nano-sized TiCx particles. An attempt was made to correlate the effect of ground CNTs by milling and the distribution of synthesized nano-sized TiCx particles in 2009Al as well as the tensile properties of nano-sized TiCx/2009Al composites. Microstructure analysis showed that when ground CNTs were used, the synthesized nano-sized TiCx particles dispersed more uniformly in the 2009Al matrix. Moreover, when 2 h-milled CNTs were used, the 5, 7, and 9 vol% nano-sized TiCx/2009Al composites had the highest tensile properties, especially, the 9 vol% nano-sized TiCx/2009Al composites. The results offered a new approach to improve the distribution of in situ nano-sized TiCx particles and tensile properties of composites. PMID:28793749

Nano ZnO embedded in Chitosan matrix for vibration sensor application

NASA Astrophysics Data System (ADS)

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

2015-06-01

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

New High-Performance Droplet Freezing Assay (HP-DFA) for the Analysis of Ice Nuclei with Complex Composition

NASA Astrophysics Data System (ADS)

Kunert, Anna Theresa; Scheel, Jan Frederik; Helleis, Frank; Klimach, Thomas; Pöschl, Ulrich; Fröhlich-Nowoisky, Janine

2016-04-01

Freezing of water above homogeneous freezing is catalyzed by ice nucleation active (INA) particles called ice nuclei (IN), which can be of various inorganic or biological origin. The freezing temperatures reach up to -1 °C for some biological samples and are dependent on the chemical composition of the IN. The standard method to analyze IN in solution is the droplet freezing assay (DFA) established by Gabor Vali in 1970. Several modifications and improvements were already made within the last decades, but they are still limited by either small droplet numbers, large droplet volumes or inadequate separation of the single droplets resulting in mutual interferences and therefore improper measurements. The probability that miscellaneous IN are concentrated together in one droplet increases with the volume of the droplet, which can be described by the Poisson distribution. At a given concentration, the partition of a droplet into several smaller droplets leads to finely dispersed IN resulting in better statistics and therefore in a better resolution of the nucleation spectrum. We designed a new customized high-performance droplet freezing assay (HP-DFA), which represents an upgrade of the previously existing DFAs in terms of temperature range and statistics. The necessity of observing freezing events at temperatures lower than homogeneous freezing due to freezing point depression, requires high-performance thermostats combined with an optimal insulation. Furthermore, we developed a cooling setup, which allows both huge and tiny temperature changes within a very short period of time. Besides that, the new DFA provides the analysis of more than 750 droplets per run with a small droplet volume of 5 μL. This enables a fast and more precise analysis of biological samples with complex IN composition as well as better statistics for every sample at the same time.

Preparation of RuO2-TiO2/Nano-graphite composite anode for electrochemical degradation of ceftriaxone sodium.

PubMed

Li, Dong; Guo, Xiaolei; Song, Haoran; Sun, Tianyi; Wan, Jiafeng

2018-06-05

Graphite-like material is widely used for preparing various electrodes for wastewater treatment. To enhance the electrochemical degradation efficiency of Nano-graphite (Nano-G) anode, RuO 2 -TiO 2 /Nano-G composite anode was prepared through the sol-gel method and hot-press technology. RuO 2 -TiO 2 /Nano-G composite was characterized by X-ray diffraction, X-ray photoelectron spectroscopy, transmission electron microscopy and N 2 adsorption-desorption. Results showed that RuO 2 , TiO 2 and Nano-G were composited successfully, and RuO 2 and TiO 2 nanoparticles were distributed uniformly on the surface of Nano-G sheet. Specific surface area of RuO 2 -TiO 2 /Nano-G composite was higher than that of TiO 2 /Nano-G composite and Nano-G. Electrochemical performances of RuO 2 -TiO 2 /Nano-G anode were investigated by cyclic voltammetry, electrochemical impedance spectroscopy. RuO 2 -TiO 2 /Nano-G anode was applied to electrochemical degradation of ceftriaxone. The generation of hydroxyl radical (OH) was measured. Results demonstrated that RuO 2 -TiO 2 /Nano-G anode displayed enhanced electrochemical degradation efficiency towards ceftriaxone and yield of OH, which is derived from the synergetic effect between RuO 2 , TiO 2 and Nano-G, which enhance the specific surface area, improve the electrochemical oxidation activity and lower the charge transfer resistance. Besides, the possible degradation intermediates and pathways of ceftriaxone sodium were identified. This study may provide a viable and promising prospect for RuO 2 -TiO 2 /Nano-G anode towards effective electrochemical degradation of antibiotics from wastewater. Copyright © 2018 Elsevier B.V. All rights reserved.

Simultaneous measurement of monocomponent droplet temperature/refractive index, size and evaporation rate with phase rainbow refractometry

NASA Astrophysics Data System (ADS)

Wu, Yingchun; Crua, Cyril; Li, Haipeng; Saengkaew, Sawitree; Mädler, Lutz; Wu, Xuecheng; Gréhan, Gérard

2018-07-01

The accurate measurements of droplet temperature, size and evaporation rate are of great importance to characterize the heat and mass transfer during evaporation/condensation processes. The nanoscale size change of a micron-sized droplet exactly describes its transient mass transfer, but is difficult to measure because it is smaller than the resolutions of current size measurement techniques. The Phase Rainbow Refractometry (PRR) technique is developed and applied to measure droplet temperature, size and transient size changes and thereafter evaporation rate simultaneously. The measurement principle of PRR is theoretically derived, and it reveals that the phase shift of the time-resolved ripple structures linearly depends on, and can directly yield, nano-scale size changes of droplets. The PRR technique is first verified through the simulation of rainbows of droplets with changing size, and results show that PRR can precisely measure droplet refractive index, absolute size, as well as size change with absolute and relative errors within several nanometers and 0.6%, respectively, and thus PRR permits accurate measurements of transient droplet evaporation rates. The evaporations of flowing single n-nonane droplet and mono-dispersed n-heptane droplet stream are investigated by two PRR systems with a high speed linear CCD and a low speed array CCD, respectively. Their transient evaporation rates are experimentally determined and quantitatively agree well with the theoretical values predicted by classical Maxwell and Stefan-Fuchs models. With the demonstration of evaporation rate measurement of monocomponent droplet in this work, PRR is an ideal tool for measurements of transient droplet evaporation/condensation processes, and can be extended to multicomponent droplets in a wide range of industrially-relevant applications.

Development of a Tandem Electrodynamic Trap Apparatus for Merging Charged Droplets and Spectroscopic Characterization of Resultant Dried Particles.

PubMed

Kohno, Jun-Ya; Higashiura, Tetsu; Eguchi, Takaaki; Miura, Shumpei; Ogawa, Masato

2016-08-11

Materials work in multicomponent forms. A wide range of compositions must be tested to obtain the optimum composition for a specific application. We propose optimization using a series of small levitated single particles. We describe a tandem-trap apparatus for merging liquid droplets and analyzing the merged droplets and/or dried particles that are produced from the merged droplets under levitation conditions. Droplet merging was confirmed by Raman spectroscopic studies of the levitated particles. The tandem-trap apparatus enables the synthesis of a particle and spectroscopic investigation of its properties. This provides a basis for future investigation of the properties of levitated single particles.

Secondary atomization of single coal-water fuel droplets

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

Hassel, G.R.; Scaroni, A.W.

1989-03-01

The evaporative behavior of single, well characterized droplets of a lignite coal-water slurry fuel (CWSF) and a carbon black in water slurry was studied as a function of heating rate and droplet composition. Induced droplet heating rates were varied from 0 to 10{sup 5} K/s. Droplets studied were between 97 and 170 {mu}m in diameter, with compositions ranging from 25 to 60% solids by weight. The effect of a commercially available surfactant additive package on droplet evaporation rate, explosive boiling energy requirements, and agglomerate formation was assessed. Surfactant concentrations were varied from none to 2 and 4% by weight solutionmore » (1.7 and 3.6% by weight of active species on a dry coal basis). The experimental system incorporated an electrodynamic balance to hold single, free droplets, a counterpropagating pulsed laser heating arrangement, and both video and high speed cinematographic recording systems. Data were obtained for ambient droplet evaporation by monitoring the temporal size, weight, and solids concentration changes. 49 refs., 31 figs.« less

Density functional theory studies on the nano-scaled composites consisted of graphene and acyl hydrazone molecules

NASA Astrophysics Data System (ADS)

Ren, J. L.; Zhou, L.; Lv, Z. C.; Ding, C. H.; Wu, Y. H.; Bai, H. C.

2016-07-01

Graphene, which is the first obtained single atomic layer 2D materials, has drawn a great of concern in nano biotechnology due to the unique property. On one hand, acyl hydrazone compounds belonging to the Schif bases have aroused considerable attention in medicine, pharmacy, and analytical reagent. However, few understanding about the interaction between graphene and acyl hydrazone molecules is now available. And such investigations are much crucial for the applications of these new nano-scaled composites. The current work revealed theoretical investigations on the nano-scaled composites built by acyl hydrazone molecules loaded on the surface of graphene. The relative energy, electronic property and the interaction between the counterparts of graphene/acyl hydrazone composites are investigated based on the density functional theory calculations. According to the obtained adsorption energy, the formation of the nano-scaled composite from the isolated graphene and acyl hydrazone molecule is exothermic, and thus it is energetically favorable to form these nano composites in viewpoint of total energy change. The frontier molecular orbital for the nano composite is mainly distributed at the graphene part, leading to that the energy levels of the frontier molecular orbital of the nano composites are very close to that of isolated graphene. Moreover, the counterpart interaction for the graphene/acyl hydrazone composites is also explored based on the discussions of orbital hybridization, charge redistribution and Van der Waals interaction.

Fabrication and Evaluation of Bis-GMA/TEGDMA Dental Resins/Composites Containing Nano Fibrillar Silicate

PubMed Central

Tian, Ming; Gao, Yi; Liu, Yi; Liao, Yiliang; Hedin, Nyle E.; Fong, Hao

2008-01-01

Objective To investigate the reinforcement of Bis-GMA/TEGDMA dental resins (without conventional glass filler) and composites (with conventional glass filler) with various mass fractions of nano fibrillar silicate (FS). Methods Three dispersion methods were studied to separate the silanized FS as nano-scaled single crystals and uniformly distribute them into dental matrices. The photo-curing behaviors of the Bis-GMA/TEGDMA/FS resins were monitored in situ by RT-NIR to study the photopolymerization rate and the vinyl double bond conversion. Mechanical properties (flexural strength, elastic modulus and work of fracture) of the nano FS reinforced resins/composites were tested, and Analysis of Variance (ANOVA) was used for the statistical analysis of the acquired data. The morphology of nano FS and the representative fracture surfaces of its reinforced resins/composites were examined by SEM/TEM. Results Impregnation of small mass fractions (1 % and 2.5 %) of nano FS into Bis-GMA/TEGDMA (50/50 mass ratio) dental resins/composites improved the mechanical properties substantially. Larger mass fraction of impregnation (7.5 %), however, did not further improve the mechanical properties (one way ANOVA, P > 0.05) and may even reduce the mechanical properties. The high degree of separation and uniform distribution of nano FS into dental resins/composites was a challenge. Impregnation of nano FS into dental resins/composites could result in two opposite effects: a reinforcing effect due to the highly separated and uniformly distributed nano FS single crystals, or a weakening effect due to the formation of FS agglomerates/particles. Significance Uniform distribution of highly separated nano FS single crystals into dental resins/composites could significantly improve the mechanical properties of the resins/composites. PMID:17572485

Fabrication and evaluation of Bis-GMA/TEGDMA dental resins/composites containing nano fibrillar silicate.

PubMed

Tian, Ming; Gao, Yi; Liu, Yi; Liao, Yiliang; Hedin, Nyle E; Fong, Hao

2008-02-01

To investigate the reinforcement of Bis-GMA/TEGDMA dental resins (without conventional glass filler) and composites (with conventional glass filler) with various mass fractions of nano fibrillar silicate (FS). Three dispersion methods were studied to separate the silanized FS as nano-scaled single crystals and uniformly distribute them into dental matrices. The photo-curing behaviors of the Bis-GMA/TEGDMA/FS resins were monitored in situ by RT-NIR to study the photopolymerization rate and the vinyl double bond conversion. Mechanical properties (flexural strength, elastic modulus and work-of-fracture) of the nano FS reinforced resins/composites were tested, and analysis of variance (ANOVA) was used for the statistical analysis of the acquired data. The morphology of nano FS and the representative fracture surfaces of its reinforced resins/composites were examined by SEM/TEM. Impregnation of small mass fractions (1% and 2.5%) of nano FS into Bis-GMA/TEGDMA (50/50 mass ratio) dental resins/composites improved the mechanical properties substantially. Larger mass fraction of impregnation (7.5%), however, did not further improve the mechanical properties (one way ANOVA, P>0.05) and may even reduce the mechanical properties. The high degree of separation and uniform distribution of nano FS into dental resins/composites was a challenge. Impregnation of nano FS into dental resins/composites could result in two opposite effects: a reinforcing effect due to the highly separated and uniformly distributed nano FS single crystals, or a weakening effect due to the formation of FS agglomerates/particles. Uniform distribution of highly separated nano FS single crystals into dental resins/composites could significantly improve the mechanical properties of the resins/composites.

Effect of wettability and topological features of Namib beetle inspired bumps on dropwise condensation

NASA Astrophysics Data System (ADS)

Ahmad, Shakeel; Tang, Hui; Yao, Haimin

2017-11-01

The Stenocara beetle lives in arid desert environment where the only available source of water is fog droplets. The beetle contains many hydrophobic/hydrophilic bumps on its back. Water collection occurs on the hydrophilic patches. Once the droplet reaches the critical volume, it sheds down due to gravity. Although a number of studies on condensation and water collection on beetle inspired structures have been reported in literature, most of them were on micro/nano scale textures. However, in nature the beetle bumps are in millimeter scale. At this scale the role of topological features and gravity becomes crucial for early droplet shedding. Therefore, in this work we numerically investigated the effects of bump shape, wettability contrast, surface slope and hydrophilic patch to total area ratio on droplet shedding volume and time. A three-dimensional lattice Boltzmann method (LBM) based numerical framework was used for the simulations. Compared with bumps of other shapes such a cube or a circular cylinder, faster droplet shedding was obtained over a hemispherical bump. Furthermore, it was found that larger hydrophilic patch to total area ratio for the hemispherical bump significantly increased the droplet shedding time.

Modeling the Transport Phenomena in the Solution Precursor Plasma Spraying

NASA Astrophysics Data System (ADS)

Shan, Yanguang

2008-10-01

Solution precursor plasma spraying has been used to produce finely structured ceramic coatings with nano- and sub-micrometric features. This process involves the injection of a solution spray of ceramic salts into a DC plasma jet under atmospheric condition. During the process, the solvent vaporizes as the droplet travel downstream. Solid particles are finally formed due to the precipitation of the solute, and the particle are heated up and accelerated to the substrate to generate the coating. This work describes a 3D model to simulate the transport phenomena and the trajectory and heating of the solution spray in the process. The jet-spray two-way interactions are considered. A simplified model is employed to simulate the evolution process and the formation of the solid particle from the solution droplet in the plasma jet. O'Rourke's droplet collision model is used to take into account of the influence of droplet collision. The influence of droplet breakup is also considered by implementing TAB droplet breakup models into the plasma jet model. The temperature and velocity fields of the jet are obtained and validated. The particle size, velocity, temperature and position distribution on the substrate are predicted.

Exploding the Myth: Enhancing the Expression of Faith and Spirituality through the Study of Dance Composition in Christian Tertiary Education

ERIC Educational Resources Information Center

Coleman, Lucinda

2011-01-01

For dance educators engaged in teaching choreography in Christian tertiary institutes, encouraging students to develop foundational compositional skills whilst exploring personal expression of the Christian faith is undoubtedly a challenging objective. In 2005, a Christian tertiary education provider in South Australia enrolled six female dance…

Direct current dielectrophoretic manipulation of the ionic liquid droplets in water.

PubMed

Zhao, Kai; Li, Dongqing

2018-07-13

The ionic liquids (ILs) as the environmentally benign solvents show great potentials in microemulsion carrier systems and have been widely used in the biochemical and pharmaceutical fields. In the work, the ionic liquid-in-water microemulsions were fabricated by using two kinds of hydrophobic ionic liquid, 1-Butyl-3-methylimidazolium hexafluorophosphate [Bmim][PF 6 ] and 1-Hexyl-3-methylimidazolium hexafluorophosphate [Hmim][PF 6 ] with Tween 20. The ionic liquid droplets in water experience the dielectrophoretic (DEP) forces induced by applying electrical field via a nano-orifice and a micron orifice on the opposite channel walls of a microchannel. The dielectrophoretic behaviors of the ionic liquid-in-water emulsion droplets were investigated under direct current (DC) electric field. The positive and negative DEP behaviors of the ionic liquid-in-water droplets varying with the electrical conductivity of the suspending medium were investigated and two kinds of the ionic liquid droplets of similar sizes were separated by their different DEP behaviors. In addition, the separation of the ionic liquid-in-water droplets by size was conducted. This paper, for the first time to our knowledge, presents the DC-DEP manipulation of the ionic liquid-in-water emulsion droplets by size and by type. This method provides a platform to manipulate the ionic liquid droplets individually. Copyright © 2018 Elsevier B.V. All rights reserved.

Instability of nano- and microscale liquid metal filaments: Transition from single droplet collapse to multidroplet breakup

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

Hartnett, Chris A.; Mahady, Kyle; Fowlkes, Jason Davidson

We carry out experimental and numerical studies to investigate the collapse and breakup of finite size, nano- and microscale, liquid metal filaments supported on a substrate. We find the critical dimensions below which filaments do not break up but rather collapse to a single droplet. The transition from collapse to breakup can be described as a competition between two fluid dynamic phenomena: the capillary driven end retraction and the Rayleigh–Plateau type instability mechanism that drives the breakup. We focus on the unique spatial and temporal transition region between these two phenomena using patterned metallic thin film strips and pulsed-laser-induced dewetting.more » The experimental results are compared to an analytical model proposed by Driessen et al. and modified to include substrate interactions. Additionally, we report the results of numerical simulations based on a volume-of-fluid method to provide additional insight and highlight the importance of liquid metal resolidification, which reduces inertial effects.« less

Instability of nano- and microscale liquid metal filaments: Transition from single droplet collapse to multidroplet breakup

DOE PAGES

Hartnett, Chris A.; Mahady, Kyle; Fowlkes, Jason Davidson; ...

2015-11-23

We carry out experimental and numerical studies to investigate the collapse and breakup of finite size, nano- and microscale, liquid metal filaments supported on a substrate. We find the critical dimensions below which filaments do not break up but rather collapse to a single droplet. The transition from collapse to breakup can be described as a competition between two fluid dynamic phenomena: the capillary driven end retraction and the Rayleigh–Plateau type instability mechanism that drives the breakup. We focus on the unique spatial and temporal transition region between these two phenomena using patterned metallic thin film strips and pulsed-laser-induced dewetting.more » The experimental results are compared to an analytical model proposed by Driessen et al. and modified to include substrate interactions. Additionally, we report the results of numerical simulations based on a volume-of-fluid method to provide additional insight and highlight the importance of liquid metal resolidification, which reduces inertial effects.« less

Surfaces for high heat dissipation with no Leidenfrost limit

NASA Astrophysics Data System (ADS)

Sajadi, Seyed Mohammad; Irajizad, Peyman; Kashyap, Varun; Farokhnia, Nazanin; Ghasemi, Hadi

2017-07-01

Heat dissipation from hot surfaces through cooling droplets is limited by the Leidenfrost point (LFP), in which an insulating vapor film prevents direct contact between the cooling droplet and the hot surface. A range of approaches have been developed to raise this limit to higher temperatures, but the limit still exists. Recently, a surface architecture, decoupled hierarchical structure, was developed that allows the suppression of LFP completely. However, heat dissipation by the structure in the low superheat region was inferior to other surfaces and the structure required an extensive micro/nano fabrication procedure. Here, we present a metallic surface structure with no LFP and high heat dissipation capacity in all temperature ranges. The surface features the nucleate boiling phenomenon independent of the temperature with an approximate heat transfer coefficient of 20 kW m-2 K-1. This surface is developed in a one-step process with no micro/nano fabrication. We envision that this metallic surface provides a unique platform for high heat dissipation in power generation, photonics/electronics, and aviation systems.

Fabrication of magnetic nano liquid metal fluid through loading of Ni nanoparticles into gallium or its alloy

NASA Astrophysics Data System (ADS)

Xiong, Mingfeng; Gao, Yunxia; Liu, Jing

2014-03-01

In this study, Ni nanoparticles were loaded into the partially oxidized gallium and its alloys to fabricate desired magnetic nanofluid. It was disclosed that the Ni nanoparticles sharply increased the freezing temperature and latent heat of the obtained magnetic nano liquid metal fluid, while the melting process was less affected. For the gallium sample added with 10 vol% coated Ni particles, a hysteresis loop was observed and the magnetization intensity decreased with the increase of the temperature. The slope for the magnetization-temperature curve within 10-30 K was about 20 times of that from 40 K to 400 K. Further, the dynamic impact experiments of striking magnetic liquid metal droplets on the magnet revealed that the regurgitating of the leading edge of the liquid disk and the subsequent wave that often occurred in the gallium-indium droplets would disappear for the magnetic fluids case due to attraction force of the magnet.

Development of optimized self-nano-emulsifying drug delivery systems (SNEDDS) of carvedilol with enhanced bioavailability potential.

PubMed

Singh, Bhupinder; Khurana, Lalit; Bandyopadhyay, Shantanu; Kapil, Rishi; Katare, O O P

2011-11-01

Carvedilol, a widely prescribed cardiovascular drug for hypertension and congestive heart failure, exhibits low and variable bioavailability owing to poor absorption and extensive hepatic first-pass metabolism. The current research work, therefore, entails formulation development of liquid self-nano-emulsifying drug delivery systems (SNEDDS) to enhance the bioavailability of carvedilol by facilitating its transport via lymphatic circulation. The formulation constituents, i.e. lipids, surfactants, and co-surfactants, were selected on the basis of solubility studies. Pseudo-ternary phase diagrams were constructed to embark upon the selection of blend of lipidic (i.e. Capmul PG8) and hydrophilic components (i.e. Cremophor EL as surfactant and Transcutol HP as co-surfactant) for efficient and robust formulation of SNEDDS. The SNEDDS, systematically optimized employing a central composite design (CCD), were evaluated for various response variables viz drug release parameters, emulsification time, emulsion droplet size, and mean dissolution time. In vitro drug release studies depicted that the release from SNEDDS systems followed a non-Fickian kinetic behavior. The TEM imaging of the optimized formulation affirmed the uniform shape and nano size of the system. Accelerated studies of the optimized formulation indicated high stability of the formulation for 6 months. The in situ perfusion studies carried out in wistar rats construed several fold augmentation in the permeability and absorption potential of the optimized formulation vis-à-vis marketed formulation. Thus, the present studies ratified the potential of SNEDDS in augmenting the oral bioavailability of BCS class II drugs.

Grain Refinement and Mechanical Properties of Cu–Cr–Zr Alloys with Different Nano-Sized TiCp Addition

PubMed Central

Zhang, Dongdong; Bai, Fang; Wang, Yong; Wang, Jinguo; Wang, Wenquan

2017-01-01

The TiCp/Cu master alloy was prepared via thermal explosion reaction. Afterwards, the nano-sized TiCp/Cu master alloy was dispersed by electromagnetic stirring casting into the melting Cu–Cr–Zr alloys to fabricate the nano-sized TiCp-reinforced Cu–Cr–Zr composites. Results show that nano-sized TiCp can effectively refine the grain size of Cu–Cr–Zr alloys. The morphologies of grain in Cu–Cr–Zr composites changed from dendritic grain to equiaxed crystal because of the addition and dispersion of nano-sized TiCp. The grain size decreased from 82 to 28 μm with the nano-sized TiCp content. Compared with Cu–Cr–Zr alloys, the ultimate compressive strength (σUCS) and yield strength (σ0.2) of 4 wt% TiCp-reinforced Cu–Cr–Zr composites increased by 6.7% and 9.4%, respectively. The wear resistance of the nano-sized TiCp-reinforced Cu–Cr–Zr composites increased with the increasing nano-sized TiCp content. The wear loss of the nano-sized TiCp-reinforced Cu–Cr–Zr composites decreased with the increasing TiCp content under abrasive particles. The eletrical conductivity of Cu–Cr–Zr alloys, 2% and 4% nano-sized TiCp-reinforced Cu–Cr–Zr composites are 64.71% IACS, 56.77% IACS and 52.93% IACS, respectively. PMID:28786937

Are nano-composites and nano-ionomers suitable for orthodontic bracket bonding?

PubMed

Uysal, Tancan; Yagci, Ahmet; Uysal, Banu; Akdogan, Gülsen

2010-02-01

The aim of this study was to test nano-composite (Filtek Supreme Plus Universal) and a newly introduced nano-ionomer (Ketac N100 Light Curing Nano-Ionomer) restorative to determine their shear bond strength (SBS) and failure site locations in comparison with a conventional light-cure orthodontic bonding adhesive (Transbond XT). Sixty freshly extracted human maxillary premolar teeth were arbitrarily divided into three equal groups. The brackets were bonded to the teeth in each group with different composites, according to the manufacturers' instructions. The SBS values of the brackets were recorded in Megapascals (MPa) using a universal testing machine. Adhesive remnant index scores were determined after failure of the brackets. The data were analysed using analysis of variance, Tukey honestly significant difference, and chi-square tests. The results demonstrated that group 1 (Transbond XT, mean: 12.60 +/- 4.48 MPa) had a higher SBS than that of group 2 (nano-composite, mean: 8.33 +/- 5.16 MPa; P < 0.05) and group 3 (nano-ionomer, mean: 6.14 +/- 2.12 MPa; P < 0.001). No significant differences in debond locations were found among the three groups. Nano-composites and nano-ionomers may be suitable for bonding since they fulfil the previously suggested SBS ranges for clinical acceptability, but they are inferior to a conventional orthodontic composite.

Nano-composite materials

DOEpatents

Lee, Se-Hee; Tracy, C. Edwin; Pitts, J. Roland

2010-05-25

Nano-composite materials are disclosed. An exemplary method of producing a nano-composite material may comprise co-sputtering a transition metal and a refractory metal in a reactive atmosphere. The method may also comprise co-depositing a transition metal and a refractory metal composite structure on a substrate. The method may further comprise thermally annealing the deposited transition metal and refractory metal composite structure in a reactive atmosphere.

A review on the application of inorganic nano-structured materials in the modification of textiles: focus on anti-microbial properties.

PubMed

Dastjerdi, Roya; Montazer, Majid

2010-08-01

Textiles can provide a suitable substrate to grow micro-organisms especially at appropriate humidity and temperature in contact to human body. Recently, increasing public concern about hygiene has been driving many investigations for anti-microbial modification of textiles. However, using many anti-microbial agents has been avoided because of their possible harmful or toxic effects. Application of inorganic nano-particles and their nano-composites would be a good alternative. This review paper has focused on the properties and applications of inorganic nano-structured materials with good anti-microbial activity potential for textile modification. The discussed nano-structured anti-microbial agents include TiO(2) nano-particles, metallic and non-metallic TiO(2) nano-composites, titania nanotubes (TNTs), silver nano-particles, silver-based nano-structured materials, gold nano-particles, zinc oxide nano-particles and nano-rods, copper nano-particles, carbon nanotubes (CNTs), nano-clay and its modified forms, gallium, liposomes loaded nano-particles, metallic and inorganic dendrimers nano-composite, nano-capsules and cyclodextrins containing nano-particles. This review is also concerned with the application methods for the modification of textiles using nano-structured materials. Copyright 2010 Elsevier B.V. All rights reserved.

A critical review of nanotechnologies for composite aerospace structures

NASA Astrophysics Data System (ADS)

Kostopoulos, Vassilis; Masouras, Athanasios; Baltopoulos, Athanasios; Vavouliotis, Antonios; Sotiriadis, George; Pambaguian, Laurent

2017-03-01

The past decade extensive efforts have been invested in understanding the nano-scale and revealing the capabilities offered by nanotechnology products to structural materials. Integration of nano-particles into fiber composites concludes to multi-scale reinforced composites and has opened a new wide range of multi-functional materials in industry. In this direction, a variety of carbon based nano-fillers has been proposed and employed, individually or in combination in hybrid forms, to approach the desired performance. Nevertheless, a major issue faced lately more seriously due to the interest of industry is on how to incorporate these nano-species into the final composite structure through existing manufacturing processes and infrastructure. This interest originates from several industrial applications needs that request the development of new multi-functional materials which combine enhanced mechanical, electrical and thermal properties. In this work, an attempt is performed to review the most representative processes and related performances reported in literature and the experience obtained on nano-enabling technologies of fiber composite materials. This review focuses on the two main composite manufacturing technologies used by the aerospace industry; Prepreg/Autoclave and Resin Transfer technologies. It addresses several approaches for nano-enabling of composites for these two routes and reports latest achieved results focusing on performance of nano-enabled fiber reinforced composites extracted from literature. Finally, this review work identifies the gap between available nano-technology integration routes and the established industrial composite manufacturing techniques and the challenges to increase the Technology Readiness Level to reach the demands for aerospace industry applications.

Nano-composites for water remediation: a review.

PubMed

Tesh, Sarah J; Scott, Thomas B

2014-09-17

As global populations continue to increase, the pressure on water supplies will inevitably intensify. Consequently the international need for more efficient and cost effective water remediation technologies will also rise. The introduction of nano-technology into the industry may represent a significant advancement and zero-valent iron nano-particles (INPs) have been thoroughly studied for potential remediation applications. However, the application of water dispersed INP suspensions is limited and somewhat contentious on the grounds of safety, whilst INP reaction mechanisms, transport properties and ecotoxicity are areas still under investigation. Theoretically, the development of nano-composites containing INPs to overcome these issues provides the logical next step for developing nano-materials that are better suited to wide application across the water industry. This review provides an overview of the range of static, bulk nano-composites containing INPs being developed, whilst highlighting the limitations of individual solutions, overall classes of technology, and lack of comparative testing for nano-composites. The review discusses what further developments are needed to optimize nano-composite water remediation systems to subsequently achieve commercial maturity. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Research on the Dielectric Properties of Nano-ZnO/Silicone Rubber Composites

NASA Astrophysics Data System (ADS)

Wang, Fei-feng; Yan, Dan-dan; Su, Yi; Lu, Yu-feng; Xia, Xiao-fei; Huang, Hui-min

2017-09-01

The samples of 1%, 2%, 3% and 4% Zinc Oxide (ZnO) nano-composite silicone rubber were prepared by mechanical method. The dielectric properties of each sample were measured by dielectric spectroscopy. The experimental results showed that the dielectric constant of the silicone rubber composite increases with the increase of the content of nano-ZnO. The breakdown test results showed that with the increase of the content of nano-ZnO, the breakdown strength of silicone rubber composites increased first and then decreased. The breakdown test results indicate that the nano-ZnO can reduce the breakdown strength of silicone rubber. The hydrophobic test results showed that nano-ZnO will reduce the hydrophobic of silicone rubber.

Engineering Interfacial Processes at Mini-Micro-Nano Scales Using Sessile Droplet Architecture.

PubMed

Bansal, Lalit; Sanyal, Apratim; Kabi, Prasenjit; Pathak, Binita; Basu, Saptarshi

2018-03-01

Evaporating sessile functional droplets act as the fundamental building block that controls the cumulative outcome of many industrial and biological applications such as surface patterning, 3D printing, photonic crystals, and DNA sequencing, to name a few. Additionally, a drying single sessile droplet forms a high-throughput processing technique using low material volume which is especially suitable for medical diagnosis. A sessile droplet also provides an elementary platform to study and analyze fundamental interfacial processes at various length scales ranging from macroscopically observable wetting and evaporation to microfluidic transport to interparticle forces operating at a nanometric length scale. As an example, to ascertain the quality of 3D printing we must understand the fundamental interfacial processes at the droplet scale. In this article, we review the coupled physics of evaporation flow-contact-line-driven particle transport in sessile colloidal droplets and provide methodologies to control the same. Through natural alterations in droplet vaporization, one can change the evaporative pattern and contact line dynamics leading to internal flow which will modulate the final particle assembly in a nontrivial fashion. We further show that control over particle transport can also be exerted by external stimuli which can be thermal, mechanical oscillations, vapor confinement (walled or a fellow droplet), or chemical (surfactant-induced) in nature. For example, significant augmentation of an otherwise evaporation-driven particle transport in sessile droplets can be brought about simply through controlled interfacial oscillations. The ability to control the final morphologies by manipulating the governing interfacial mechanisms in the precursor stages of droplet drying makes it perfectly suitable for fabrication-, mixing-, and diagnostic-based applications.

A comparative study of gelatin and starch-based nano-composite films modified by nano-cellulose and chitosan for food packaging applications.

PubMed

Noorbakhsh-Soltani, S M; Zerafat, M M; Sabbaghi, S

2018-06-01

Environmental concerns have led to extensive research for replacing polymer-based food packaging with bio-nano-composites. In this study, incorporation of nano-cellulose into gelatin and starch matrices is investigated for this purpose. Chitosan is used to improve mechanical, anti-fungal and waterproof properties. Experiments are designed and analyzed using response surface methodology. Nano-Cellulose is synthesized via acid hydrolysis and incorporated in base matrices through wet processing. Also, tensile strength test, food preservation, transparency in visible and UV and water contact angle are performed on the nano-composite films. DSC/TGA and air permeability tests are also performed on the optimal films. The results show that increasing nano-cellulose composition to 10% leads to increase the tensile strength at break to 8121 MN/m 2 and decrease the elongation at break. Also, increasing chitosan composition from 5% to 30% can enhance food preservation up to 15 days. Copyright © 2018 Elsevier Ltd. All rights reserved.

[Dental plaque microcosm biofilm behavior on a resin composite incorporated with nano-antibacterial inorganic filler containing long-chain alkyl quaternary ammonium salt].

PubMed

Junling, Wu; Qiang, Zhang; Ruinan, Sun; Ting, Zhu; Jianhua, Ge; Chuanjian, Zhou

2015-12-01

To develop a resin composite incorporated with nano-antibacterial inorganic filler containing long-chain alkyl quaternary ammonium salt, and to measure its effect on human dental plaque microcosm biofilm. A novel nano-antibacterial inorganic filler containing long-chain alkyl quaternary ammonium salt was synthesized according to methods introduced in previous research. Samples of the novel nano-antibacterial inorganic fillers were modified by a coupling agent and then added into resin composite at 0%, 5%, 10%, 15% or 20% mass fractions; 0% composite was used as control. A flexural test was used to measure resin composite mechanical properties. Results showed that a dental plaque microcosm biofilm model with human saliva as inoculum was formed. Colony-forming unit (CFU) counts, lactic acid production, and live/dead assay of biofilm on the resin composite were calculated to test the effect of the resin composite on human dental plaque microcosm biofilm. The incorporation of nano-antibacterial inorganic fillers with as much as 15% concentration into the resin composite showed no adverse effect on the mechanical properties of the resin composite (P > 0.05). Resin composite containing 5% or more nano-antibacterial inorganic fillers significantly inhibited the metabolic activity of dental plaque microcosm biofilm, suggesting its strong antibacterial potency (P < 0.05). This novel resin composite exhibited a strong antibacterial property upon the addition of up to 5% nano-antibacterial inorganic fillers, thereby leading to effective caries inhibition in dental application.

Grain Refinement and Mechanical Properties of Cu-Cr-Zr Alloys with Different Nano-Sized TiCp Addition.

PubMed

Zhang, Dongdong; Bai, Fang; Wang, Yong; Wang, Jinguo; Wang, Wenquan

2017-08-08

The TiC p /Cu master alloy was prepared via thermal explosion reaction. Afterwards, the nano-sized TiC p /Cu master alloy was dispersed by electromagnetic stirring casting into the melting Cu-Cr-Zr alloys to fabricate the nano-sized TiC p -reinforced Cu-Cr-Zr composites. Results show that nano-sized TiC p can effectively refine the grain size of Cu-Cr-Zr alloys. The morphologies of grain in Cu-Cr-Zr composites changed from dendritic grain to equiaxed crystal because of the addition and dispersion of nano-sized TiC p . The grain size decreased from 82 to 28 μm with the nano-sized TiC p content. Compared with Cu-Cr-Zr alloys, the ultimate compressive strength (σ UCS ) and yield strength (σ 0.2 ) of 4 wt% TiC p -reinforced Cu-Cr-Zr composites increased by 6.7% and 9.4%, respectively. The wear resistance of the nano-sized TiCp-reinforced Cu-Cr-Zr composites increased with the increasing nano-sized TiCp content. The wear loss of the nano-sized TiC p -reinforced Cu-Cr-Zr composites decreased with the increasing TiC p content under abrasive particles. The eletrical conductivity of Cu-Cr-Zr alloys, 2% and 4% nano-sized TiCp-reinforced Cu-Cr-Zr composites are 64.71% IACS, 56.77% IACS and 52.93% IACS, respectively.

Green synthesis of tea Ag nanocomposite hydrogels via mint leaf extraction for effective antibacterial activity.

PubMed

Jayaramudu, Tippabattini; Varaprasad, Kokkarachedu; Raghavendra, Gownolla Malegowd; Sadiku, E R; Mohana Raju, Konduru; Amalraj, John

2017-10-01

In this report, we investigated the swelling behavior and antibacterial property of nanosilver composite hydrogels made from tea with polyacrylamide via a free-radical polymerization and green process technique. This is probably for the first time; tea-based nano silver composite hydrogels were developed. The composite hydrogels comprise embedded nano silver particles in the tea hydrogel matrix via a green process with mint leaf extract. The size of the nano silver particles in the hydrogel matrix was found to be < 10 nm. The nano silver composite hydrogels formed and their blank hydrogels from the mint leaf were characterized by using ultraviolet-visible spectroscopy, scanning electron microscopy with energy dispersive spectroscopy, transmission electron microscopy, thermogravimetric analysis and X-ray diffraction studies. The nano silver composite hydrogels developed exhibit eminent antibacterial activity against Escherichia coli and Staphylococcus aureus. This clearly indicates that the nano silver composite hydrogels are potential candidates for antimicrobial applications.

Acoustic and photoacoustic characterization of micron-sized perfluorocarbon emulsions

NASA Astrophysics Data System (ADS)

Strohm, Eric M.; Gorelikov, Ivan; Matsuura, Naomi; Kolios, Michael C.

2012-09-01

Perfluorocarbon droplets containing nanoparticles (NPs) have recently been investigated as theranostic and dual-mode contrast agents. These droplets can be vaporized via laser irradiation or used as photoacoustic contrast agents below the vaporization threshold. This study investigates the photoacoustic mechanism of NP-loaded droplets using photoacoustic frequencies between 100 and 1000 MHz, where distinct spectral features are observed that are related to the droplet composition. The measured photoacoustic spectrum from NP-loaded perfluorocarbon droplets was compared to a theoretical model that assumes a homogenous liquid. Good agreement in the location of the spectral features was observed, which suggests the NPs act primarily as optical absorbers to induce thermal expansion of the droplet as a single homogenous object. The NP size and composition do not affect the photoacoustic spectrum; therefore, the photoacoustic signal can be maximized by optimizing the NP optical absorbing properties. To confirm the theoretical parameters in the model, photoacoustic, ultrasonic, and optical methods were used to estimate the droplet diameter. Photoacoustic and ultrasonic methods agreed to within 1.4%, while the optical measurement was 8.5% higher; this difference decreased with increasing droplet size. The small discrepancy may be attributed to the difficulty in observing the small droplets through the partially translucent phantom.

Acoustic and photoacoustic characterization of micron-sized perfluorocarbon emulsions.

PubMed

Strohm, Eric M; Gorelikov, Ivan; Matsuura, Naomi; Kolios, Michael C

2012-09-01

Perfluorocarbon droplets containing nanoparticles (NPs) have recently been investigated as theranostic and dual-mode contrast agents. These droplets can be vaporized via laser irradiation or used as photoacoustic contrast agents below the vaporization threshold. This study investigates the photoacoustic mechanism of NP-loaded droplets using photoacoustic frequencies between 100 and 1000 MHz, where distinct spectral features are observed that are related to the droplet composition. The measured photoacoustic spectrum from NP-loaded perfluorocarbon droplets was compared to a theoretical model that assumes a homogenous liquid. Good agreement in the location of the spectral features was observed, which suggests the NPs act primarily as optical absorbers to induce thermal expansion of the droplet as a single homogenous object. The NP size and composition do not affect the photoacoustic spectrum; therefore, the photoacoustic signal can be maximized by optimizing the NP optical absorbing properties. To confirm the theoretical parameters in the model, photoacoustic, ultrasonic, and optical methods were used to estimate the droplet diameter. Photoacoustic and ultrasonic methods agreed to within 1.4%, while the optical measurement was 8.5% higher; this difference decreased with increasing droplet size. The small discrepancy may be attributed to the difficulty in observing the small droplets through the partially translucent phantom.

Preparation of SiC based Aluminium metal matrix nano composites by high intensity ultrasonic cavitation process and evaluation of mechanical and tribological properties

NASA Astrophysics Data System (ADS)

Murthy, N. V.; Prasad Reddy, A.; Selvaraj, N.; Rao, C. S. P.

2016-09-01

Request augments on a worldwide scale for the new materials. The metal matrix nano composites can be used in numerous applications of helicopter structural parts, gas turbine exit guide vane's, space shuttle, and other structural applications. The key mailman to ameliorate performance of composite matrix in aluminium alloy metal reinforces nano particles in the matrix of alloy uniformly, which ameliorates composite properties without affecting limit of ductility. The ultrasonic assisted stir casting helped agitation was successfully used to fabricate Al 2219 metal matrix of alloy reinforced with (0.5, 1, 1.5 and 2) wt.% of nano silicon carbide (SiC) particles of different sizes 50nm and 150nm. The micrographs of scanning electron microscopy of nano composite were investigated it reveals that the uniform dispersion of nano particles silicon carbide in aluminium alloy 2219 matrix and with the low porosity. How the specific wear rate was vary with increasing weight percentage of nano particles at constant load and speed as shown in results and discussions. And the mechanical properties showed that the ultimate tensile strength and hardness of metal matrix nano composite AA 2219 / nano SiC of 50nm and 150nm lean to augment with increase weight percentage of silicon carbide content in the matrix alloy.

Cooperative cytotoxic activity of Zn and Cu in bovine serum albumin-conjugated ZnS/CuS nano-composites in PC12 cancer cells

NASA Astrophysics Data System (ADS)

Wang, Hua-Jie; Yu, Xue-Hong; Wang, Cai-Feng; Cao, Ying

2013-11-01

Series of self-assembled and mono-dispersed bovine serum albumin (BSA)-conjugated ZnS/CuS nano-composites with different Zn/Cu ratios had been successfully synthesized by a combination method of the biomimetic synthesis and ion-exchange strategy under the gentle conditions. High-resolution transmission electron microscopy observation, Fourier transform infrared spectra and zeta potential analysis demonstrated that BSA-conjugated ZnS/CuS nano-composites with well dispersity had the hierarchical structure and BSA was a key factor to control the morphology and surface electro-negativity of final products. The real-time monitoring by atomic absorption spectroscopy and powder X-ray diffraction revealed that the Zn/Cu ratio of nano-composites could be controlled by adjusting the ion-exchange time. In addition, the metabolic and morphological assays indicated that the metabolic proliferation and spread of rat pheochromocytoma (PC12) cells could be inhibited by nano-composites, with the high anti-cancer activity at a low concentration (4 ppm). What were more important, Zn and Cu in nano-composites exhibited a positive cooperativity at inhibiting cancer cell functions. The microscope observation and biochemical marker analysis clearly revealed that the nano-composites-included lipid peroxidation and disintegration of membrane led to the death of PC12 cells. Summarily, the present study substantiated the potential of BSA-conjugated ZnS/CuS nano-composites as anti-cancer drug.

Nanotechnologies for Composite Structures- From Nanocomposites to Multifunctional Nano-Enabled Fibre Reinforced Composites for Spacecrafts

NASA Astrophysics Data System (ADS)

Kostopoulos, Vassilis; Vavouliotis, Antonios; Baltopoulos, Athanasios; Sotiririadis, George; Masouras, Athanasios; Pambaguian, Laurent

2014-06-01

The past decade, extensive efforts have been invested in understanding the nano-scale and revealing the capabilities offered by nanotechnology products to structural materials. Nevertheless, a major issue faced lately more seriously due to the interest of industry is on how to incorporate these nano-species into the final composite structure through existing manufacturing processes and infrastructure. In this work, we present the experience obtained from the latest nanotechnology research activities supported by ESA. The paper focuses on prepreg composite manufacturing technology and addresses:- Approaches for nano-enabling of composites- Up-scaling strategies towards final structures- Latest results on performance of nano-enabledfiber reinforced compositesSeveral approaches for the utilization of nanotechnology products in structural composite structures have been proposed and are reviewed, in short along with respective achieved results. A variety of nano-fillers has been proposed and employed, individually or in combination in hybrid forms, to approach the desired performance. A major part of the work deals with the up-scaling routes of these technologies to reach final products and industrial scales and processes while meeting end-user performance.

Au-assisted fabrication of nano-holes on c-plane sapphire via thermal treatment guided by Au nanoparticles as catalysts

NASA Astrophysics Data System (ADS)

Sui, Mao; Pandey, Puran; Li, Ming-Yu; Zhang, Quanzhen; Kunwar, Sundar; Lee, Jihoon

2017-01-01

Nanoscale patterning of sapphires is a challenging task due to the high mechanical strength, chemical stability as well as thermal durability. In this paper, we demonstrate a gold droplet assisted approach of nano-hole fabrication on c-plane sapphire via a thermal treatment. Uniformly distributed nano-holes are fabricated on the sapphire surface guided by dome shaped Au nanoparticles (NPs) as catalysts and the patterning process is discussed based on the disequilibrium of vapor, liquid, solid interface energies at the Au NP/sapphire interface induced by the Au evaporation at high temperature. Followed by the re-equilibration of interface energy, transport of alumina from the beneath of NPs to the sapphire surface can occur along the NP/sapphire interface resulting in the formation of nano-holes. The fabrication of nano-holes using Au NPs as catalysts is a flexible, economical and convenient approach and can find applications in various optoelectronics.

Lipidomic and proteomic analysis of Caenorhabditis elegans lipid droplets and identification of ACS-4 as a lipid droplet-associated protein

DOE PAGES

Vrablik, Tracy L.; Petyuk, Vladislav A.; Larson, Emily M.; ...

2015-06-27

Lipid droplets are cytoplasmic organelles that store neutral lipids for membrane synthesis and energy reserves. In this study, we characterized the lipid and protein composition of purified Caenorhabditis elegans lipid droplets. These lipid droplets are composed mainly of triacylglycerols, surrounded by a phospholipid monolayer composed primarily of phosphatidylcholine and phosphatidylethanolamine. The fatty acid composition of the triacylglycerols is rich in fatty acid species obtained from the dietary Escherichia coli, including cyclopropane fatty acids and cis-vaccenic acid. Unlike other organisms, C. elegans lipid droplets contain very little cholesterol or cholesterol esters. Comparison of the lipid droplet proteomes of wild type andmore » high-fat daf-2 mutant strains shows a very similar proteome in both strains, except that the most abundant protein in the C. elegans lipid droplet proteome, MDT-28, is relatively less abundant in lipid droplets isolated from daf-2 mutants. Functional analysis of lipid droplet proteins identified in our proteomic studies indicated an enrichment of proteins required for growth and fat homeostasis in C. elegans. Finally, we confirmed the localization of one of the newly identified lipid droplet proteins, ACS-4. We found that ACS-4 localizes to the surface of lipid droplets in the C. elegans intestine and skin. This study bolsters C. elegans as a model to study the dynamics and functions of lipid droplets in a multicellular organism.« less

Instrumentation for Nano-porous, Nano-particulate Geopolymeric Materials Research

DTIC Science & Technology

2008-11-04

and their composites . This grant was used to procure equipment to synthesize and characterize the nano- and meso-porous geopolymers , and study their...and meso-porosity and microstructure of geopolymers and their composites is part of an ongoing research project in the PIs research group, which has...the synthesis and processing of geopolymers and geopolymer composites . The attritor mill enables synthesis Technical Report of nano-sized high

Instrumentation for Nano-porous, Nano-particulate Geopolymeric Materials Research

DTIC Science & Technology

2008-11-04

working on tailoring the nano- and meso-porosity, and the microstructure of geopolymers and their composites . This grant was used to procure equipment...and tailor the nano and meso-porosity and microstructure of geopolymers and their composites is part of an ongoing research project in the Pis...purchased to improve the synthesis and processing of geopolymers and geopolymer composites . The attritor mill enables synthesis Technical Report of

Droplet activation, separation, and compositional analysis: laboratory studies and atmospheric measurements

NASA Astrophysics Data System (ADS)

Hiranuma, N.; Kohn, M.; Pekour, M. S.; Nelson, D. A.; Shilling, J. E.; Cziczo, D. J.

2011-10-01

Droplets produced in a cloud condensation nuclei chamber (CCNC) as a function of supersaturation have been separated from unactivated aerosol particles using counterflow virtual impaction. Residual material after droplets were evaporated was chemically analyzed with an Aerodyne Aerosol Mass Spectrometer (AMS) and the Particle Analysis by Laser Mass Spectrometry (PALMS) instrument. Experiments were initially conducted to verify activation conditions for monodisperse ammonium sulfate particles and to determine the resulting droplet size distribution as a function of supersaturation. Based on the observed droplet size, the counterflow virtual impactor cut-size was set to differentiate droplets from unactivated interstitial particles. Validation experiments were then performed to verify that only droplets with sufficient size passed through the counterflow virtual impactor for subsequent analysis. A two-component external mixture of monodisperse particles was also exposed to a supersaturation which would activate one of the types (hygroscopic salts) but not the other (polystyrene latex spheres or adipic acid). The mass spectrum observed after separation indicated only the former, validating separation of droplets from unactivated particles. Results from ambient measurements using this technique and AMS analysis were inconclusive, showing little chemical differentiation between ambient aerosol and activated droplet residuals, largely due to low signal levels. When employing as single particle mass spectrometer for compositional analysis, however, we observed enhancement of sulfate in droplet residuals.

Kinetic control of the coverage of oil droplets by DNA-functionalized colloids

PubMed Central

Joshi, Darshana; Bargteil, Dylan; Caciagli, Alessio; Burelbach, Jerome; Xing, Zhongyang; Nunes, André S.; Pinto, Diogo E. P.; Araújo, Nuno A. M.; Brujic, Jasna; Eiser, Erika

2016-01-01

We report a study of reversible adsorption of DNA-coated colloids on complementary functionalized oil droplets. We show that it is possible to control the surface coverage of oil droplets using colloidal particles by exploiting the fact that, during slow adsorption, compositional arrest takes place well before structural arrest occurs. As a consequence, we can prepare colloid-coated oil droplets with a “frozen” degree of loading but with fully ergodic colloidal dynamics on the droplets. We illustrate the equilibrium nature of the adsorbed colloidal phase by exploring the quasi–two-dimensional phase behavior of the adsorbed colloids under the influence of depletion interactions and present simulations of a simple model that illustrates the nature of the compositional arrest and the structural ergodicity. PMID:27532053

Characteristics of Nano-emulsion for Cold Thermal Storage

NASA Astrophysics Data System (ADS)

Fumoto, Koji; Kawaji, Masahiro; Kawanami, Tsuyoshi

Phase change emulsion (PCE) is novel kind of heat storage and heat transfer fluids. It has characteristics as follows; greater apparent specific heat and higher heat transfer abilities in the phase change temperature range than conventional single phase heat transfer fluid. In this paper, a phase change emulsion, which has droplet diameter distribution of nanometer, were prepared. The Nano-emulsion was formed by low energy emulsification methods, as known the phase inversion temperature (PIT) method. Physical properties, such as viscosity, diameter and its distribution of emulsion were investigated. Especially, the relationships between preparation method and the concentration of surfactant have been discussed in detail. The results show that the viscosity of the Nano-emulsion is lower than the micro-emulsion, which was made by same mixing ratio of surfactant and concentration of phase change material. In addition, the Nano-emulsion clarified that stability was higher than microemulsions.

Direct comparison of fatty acid ratios in single cellular lipid droplets as determined by Raman spectroscopy and gas chromatography

USDA-ARS?s Scientific Manuscript database

Cellular lipid droplets are the least studied and least understood cellular organelles in eukaryotic and prokaryotic cells. Despite a broad research trying to understand lipid droplets it has not been possible to determine the composition of individual cellular lipid droplets. In this paper we prese...

Effect of nanofiber content on bone regeneration of silk fibroin/poly(ε-caprolactone) nano/microfibrous composite scaffolds

PubMed Central

Kim, Beom Su; Park, Ko Eun; Kim, Min Hee; You, Hyung Keun; Lee, Jun; Park, Won Ho

2015-01-01

The broad application of electrospun nanofibrous scaffolds in tissue engineering is limited by their small pore size, which has a negative influence on cell migration. This disadvantage could be significantly improved through the combination of nano- and microfibrous structure. To accomplish this, different nano/microfibrous scaffolds were produced by hybrid electrospinning, combining solution electrospinning with melt electrospinning, while varying the content of the nanofiber. The morphology of the silk fibroin (SF)/poly(ε-caprolactone) (PCL) nano/microfibrous composite scaffolds was investigated with field-emission scanning electron microscopy, while the mechanical and pore properties were assessed by measurement of tensile strength and mercury porosimetry. To assay cell proliferation, cell viability, and infiltration ability, human mesenchymal stem cells were seeded on the SF/PCL nano/microfibrous composite scaffolds. From in vivo tests, it was found that the bone-regenerating ability of SF/PCL nano/microfibrous composite scaffolds was closely associated with the nanofiber content in the composite scaffolds. In conclusion, this approach of controlling the nanofiber content in SF/PCL nano/microfibrous composite scaffolds could be useful in the design of novel scaffolds for tissue engineering. PMID:25624762

Nanomaterials enhance osteogenic differentiation of human mesenchymal stem cells similar to a short peptide of BMP-7

PubMed Central

Lock, Jaclyn; Liu, Huinan

2011-01-01

Background Nanomaterials have unique advantages in controlling stem cell function due to their biomimetic characteristics and special biological and mechanical properties. Controlling adhesion and differentiation of stem cells is critical for tissue regeneration. Methods This in vitro study investigated the effects of nano-hydroxyapatite, nano-hydroxyapatite-polylactide- co-glycolide (PLGA) composites, and a bone morphogenetic protein (BMP-7)- derived short peptide (DIF-7c) on osteogenic differentiation of human mesenchymal stem cells (MSC). The peptide was chemically functionalized onto nano-hydroxyapatite, incorporated into a nanophase hydroxyapatite-PLGA composite or PLGA control, or directly injected into culture media. Results Unlike the PLGA control, the nano-hydroxyapatite-PLGA composites promoted adhesion of human MSC. Importantly, nano-hydroxyapatite and nano-hydroxyapatite-PLGA composites promoted osteogenic differentiation of human MSCs, comparable with direct injection of the DIF-7c peptide into culture media. Conclusion Nano-hydroxyapatite and nano-hydroxyapatite-PLGA composites provide a promising alternative in directing the adhesion and differentiation of human MSC. These nanocomposites should be studied further to clarify their effects on MSC functions and bone remodeling in vivo, eventually translating to clinical applications. PMID:22114505

Modeling of Fume Formation from Shielded Metal Arc Welding Process

NASA Astrophysics Data System (ADS)

Sivapirakasam, S. P.; Mohan, Sreejith; Santhosh Kumar, M. C.; Surianarayanan, M.

2017-04-01

In this study, a semi-empirical model of fume formation rate (FFR) from a shielded metal arc welding (SMAW) process has been developed. The model was developed for a DC electrode positive (DCEP) operation and involves the calculations of droplet temperature, surface area of the droplet, and partial vapor pressures of the constituents of the droplet to predict the FFR. The model was further extended for predicting FFR from nano-coated electrodes. The model estimates the FFR for Fe and Mn assuming constant proportion of other elements in the electrode. Fe FFR was overestimated, while Mn FFR was underestimated. The contribution of spatters and other mechanism in the arc responsible for fume formation were neglected. A good positive correlation was obtained between the predicted and experimental FFR values which highlighted the usefulness of the model.

Arrested of coalescence of emulsion droplets of arbitrary size

NASA Astrophysics Data System (ADS)

Mbanga, Badel L.; Burke, Christopher; Blair, Donald W.; Atherton, Timothy J.

2013-03-01

With applications ranging from food products to cosmetics via targeted drug delivery systems, structured anisotropic colloids provide an efficient way to control the structure, properties and functions of emulsions. When two fluid emulsion droplets are brought in contact, a reduction of the interfacial tension drives their coalescence into a larger droplet of the same total volume and reduced exposed area. This coalescence can be partially or totally hindered by the presence of nano or micron-size particles that coat the interface as in Pickering emulsions. We investigate numerically the dependance of the mechanical stability of these arrested shapes on the particles size, their shape anisotropy, their polydispersity, their interaction with the solvent, and the particle-particle interactions. We discuss structural shape changes that can be induced by tuning the particles interactions after arrest occurs, and provide design parameters for the relevant experiments.

Water-walled microfluidics for high-optical finesse cavities

NASA Astrophysics Data System (ADS)

Maayani, Shai; Martin, Leopoldo L.; Carmon, Tal

2016-01-01

In submerged microcavities there is a tradeoff between resonant enhancement for spatial water and light overlap. Why not transform the continuously resonating optical mode to be fully contained in a water microdroplet per se? Here we demonstrate a sustainable 30-μm-pure water device, bounded almost completely by free surfaces, enabling >1,000,000 re-circulations of light. The droplets survive for >16 h using a technique that is based on a nano-water bridge from the droplet to a distant reservoir to compensate for evaporation. More than enabling a nearly-perfect optical overlap with water, atomic-level surface smoothness that minimizes scattering loss, and ~99% coupling efficiency from a standard fibre. Surface tension in our droplet is 8,000 times stronger than gravity, suggesting a new class of devices with water-made walls, for new fields of study including opto-capillaries.

Wear Resistance Properties Reinforcement Using Nano-Al/Cu Composite Coating in Sliding Bearing Maintenance.

PubMed

Liu, Hongtao; Li, Zhixiong; Wang, Jianmei; Sheng, Chenxing; Liu, Wanli

2018-03-01

Sliding bearing maintenance is crucial for reducing the cost and extending the service life. An efficient and practical solution is to coat a restorative agent onto the worn/damaged bearings. Traditional pure-copper (Cu) coating results in a soft surface and poor abrasion resistance. To address this issue, this paper presents a nano-composite repairing coating method. A series of nano-Al/Cu coatings were prepared on the surface of 45 steel by composite electro-brush plating (EBP). Their micro-hardness was examined by a MHV-2000 Vickers hardness tester, and tribological properties by a UMT-2M Micro-friction tester, 3D profiler and SEM. Then, the influence of processing parameters such as nano-particle concentration and coating thickness on the micro-hardness of nano-Al/Cu coating was analyzed. The experimental analysis results demonstrate that, when the nano-Al particle concentration in electrolyte was 10 g/L, the micro-hardness of the composite coating was 1.1 times as much as that of pure-Cu coating. When the Al nano-particle concentration in electrolyte was 20 g/L, the micro-hardness of the composite coating reached its maximum value (i.e., 231.6 HV). Compared with the pure-Cu coating, the hardness and wear resistance of the nano-composite coating were increased, and the friction coefficient and wear volume were decreased, because of the grain strengthening and dispersion strengthening. The development in this work may provide a feasible and effective nano-composite EBP method for sliding bearing repair.

Could Nano-Structured Materials Enable the Improved Pressure Vessels for Deep Atmospheric Probes?

NASA Technical Reports Server (NTRS)

Srivastava, D.; Fuentes, A.; Bienstock, B.; Arnold, J. O.

2005-01-01

A viewgraph presentation on the use of Nano-Structured Materials to enable pressure vessel structures for deep atmospheric probes is shown. The topics include: 1) High Temperature/Pressure in Key X-Environments; 2) The Case for Use of Nano-Structured Materials Pressure Vessel Design; 3) Carbon based Nanomaterials; 4) Nanotube production & purification; 5) Nanomechanics of Carbon Nanotubes; 6) CNT-composites: Example (Polymer); 7) Effect of Loading sequence on Composite with 8% by volume; 8) Models for Particulate Reinforced Composites; 9) Fullerene/Ti Composite for High Strength-Insulating Layer; 10) Fullerene/Epoxy Composite for High Strength-Insulating Layer; 11) Models for Continuous Fiber Reinforced Composites; 12) Tensile Strength for Discontinuous Fiber Composite; 13) Ti + SWNT Composites: Thermal/Mechanical; 14) Ti + SWNT Composites: Tensile Strength; and 15) Nano-structured Shell for Pressure Vessels.

Multifunctional Composites through Inkjet-printed Architectures

DTIC Science & Technology

2015-03-27

were printed onto prepreg before curing, and remained arrested between composite plies without direct contact with the neighboring micro-droplets after...micro-droplets were printed onto prepreg before curing, and remained arrested between composite plies without direct contact with the neighbouring...unidirectional carbon fibre prepreg (Cycom 977-2, Cytec Industries Inc., USA) was chosen as substrate in this work. Poly(methyl methacrylate) (PMMA) (Mn = 15 kDa

Characterization of microwave assisted sintered graphene toughened alumina (GTA) nano composites

NASA Astrophysics Data System (ADS)

Vandana, K. I. Vishnu; Suman, K. N. S.; Viswabaskaran, V.

2017-07-01

The objective of the present work is to characterize different mechanical properties of a nano composite made out of a combination of nano alumina and nano graphene. The nano powders of alumina and Graphene were mixed using High Energy Ball Mill and weight ratio of Al:G-C was maintained in the range of 0 to 2wt%. The prepared alumoorganic nano Composite Powders were compacted by Uniaxial Pellet Press and Graphene Toughened alumina (GTA) based composites were sintered in inert atmosphere at 1600°C using Hybrid Microwave Furnace. XRD and SEM studies are conducted on these specimens. Density and hardness tests are also performed on these specimens. In addition, wear and fracture toughness tests will also be carried out. In order to strengthen the experimental observations obtained, theoretical interpretation will be given to enhance the present work.

[Study on spectroscopic characterization and property of PES/ micro-nano cellulose composite membrane material].

PubMed

Tang, Huan-Wei; Zhang, Li-Ping; Li, Shuai; Zhao, Guang-Jie; Qin, Zhu; Sun, Su-Qin

2010-03-01

In the present paper, the functional groups of PES/micro-nano cellulose composite membrane materials were characterized by Fourier transform infrared spectroscopy (FTIR). Also, changes in crystallinity in composite membrane materials were analyzed using X-ray diffraction (XRD). The effects of micro-nano cellulose content on hydrophilic property of composite membrane material were studied by measuring hydrophilic angle. The images of support layer structure of pure PES membrane material and composite membrane material were showed with scanning electron microscope (SEM). These results indicated that in the infrared spectrogram, the composite membrane material had characteristic peaks of both PES and micro-nano cellulose without appearance of other new characteristics peaks. It revealed that there were no new functional groups in the composite membrane material, and the level of molecular compatibility was achieved, which was based on the existence of inter-molecular hydrogen bond association between PES and micro-nano cellulose. Due to the existence of micro-nano cellulose, the crystallinity of composite membrane material was increased from 37.7% to 47.9%. The more the increase in micro-nano cellulose mass fraction, the better the van de Waal force and hydrogen bond force between composite membrane material and water were enhanced. The hydrophilic angle of composite membrane material was decreased from 55.8 degrees to 45.8 degrees and the surface energy was raised from 113.7 to 123.5 mN x m(-2). Consequently, the hydrophilic property of composite membrane material was improved. The number of pores in the support layer of composite membrane material was lager than that of pure PES membrane. Apparently, pores were more uniformly distributed.

Effective reduction of p-nitrophenol by silver nanoparticle loaded on magnetic Fe3O4/ATO nano-composite

NASA Astrophysics Data System (ADS)

Karki, Hem Prakash; Ojha, Devi Prashad; Joshi, Mahesh Kumar; Kim, Han Joo

2018-03-01

A silver loaded hematite (Fe3O4) and antimony doped tin oxide (ATO) magnetic nano-composite (Ag-Fe3O4/ATO) was successfully synthesized by in situ one pot green and facile hydrothermal process. The formation of nano-composite, its structure, morphology, and stability were characterized by field emission scanning electron microscopy (FE-SEM), high resolution transmission electron microscopy (HRTEM), electron diffraction spectroscopy (EDS), elemental mapping by high resolution scanning transmission electron microscopy (STEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), Fourier transform infra-red spectroscopy (FTIR). UV-vis spectroscopy was used to monitor the catalytic reduction of p-nitrophenol (PNP) into p-aminophenol (PAP) in presence of Ag-Fe3O4/ATO nano-composite with excess of sodium borohydride (NaBH4). The pseudo-first order kinetic equation could describe the reduction of p-nitrophenol with excess of NaBH4. For the first time, ATO surface was used for hydrothermal growth of silver and iron oxide magnetic nanoparticles. The in situ growth of these nanoparticles provided an effective bonding of components of the nano-composite over the surface of ATO nanoparticles. This nano-composite exhibited easy synthesis, high stability, cost effective and rapid separation using external magnet. The excellent catalytic and anti-bacterial activity of as-synthesized silver nano-composite makes it potential nano-catalyst for waste water treatment as well as biomedical application.

Layer-by-layer cell membrane assembly

NASA Astrophysics Data System (ADS)

Matosevic, Sandro; Paegel, Brian M.

2013-11-01

Eukaryotic subcellular membrane systems, such as the nuclear envelope or endoplasmic reticulum, present a rich array of architecturally and compositionally complex supramolecular targets that are as yet inaccessible. Here we describe layer-by-layer phospholipid membrane assembly on microfluidic droplets, a route to structures with defined compositional asymmetry and lamellarity. Starting with phospholipid-stabilized water-in-oil droplets trapped in a static droplet array, lipid monolayer deposition proceeds as oil/water-phase boundaries pass over the droplets. Unilamellar vesicles assembled layer-by-layer support functional insertion both of purified and of in situ expressed membrane proteins. Synthesis and chemical probing of asymmetric unilamellar and double-bilayer vesicles demonstrate the programmability of both membrane lamellarity and lipid-leaflet composition during assembly. The immobilized vesicle arrays are a pragmatic experimental platform for biophysical studies of membranes and their associated proteins, particularly complexes that assemble and function in multilamellar contexts in vivo.

Novel Preparation of Nano-Composite CuO-Cr2O3 Using Ctab-Template Method and Efficient for Hydrogenation of Biomass-Derived Furfural

NASA Astrophysics Data System (ADS)

Yan, Kai; Wu, Xu; An, Xia; Xie, Xianmei

2013-02-01

A simple route to fabricate nano-composite oxides CuO-Cr2O3 using hexadecyltrimethylammonium bromide (CTAB)-templated Cu-Cr hydrotalcite as the precursor is presented. This novel method is based on CTAB-templating effect for mesostructure directing and using the cheap metal nitrate, followed by removal of CTAB. It was indicated that the nano-composite CuO-Cr2O3 was formed during the removal of CTAB. X-ray diffraction (XRD) and transitional electronic microscopy (TEM) revealed nice nano-composite oxides CuO-Cr2O3 were formed with high crystallinity. N2 adsorption and desorption indicated that a high surface area of 170.5 m2/g with a pore size of 2.7 nm of the nano-composite CuO-Cr2O3 was facilely resulted. The as-synthesized nano-composite oxides CuO-Cr2O3 display good catalytic activities for hydrogenation of furfural to furfuryl alcohol, whereas 86% selectivity was achieved at 75% conversion of furfural.

Lipidomic data on lipid droplet triglyceride remodelling associated with protection of breast cancer cells from lipotoxic stress.

PubMed

Jarc, Eva; Eichmann, Thomas O; Zimmermann, Robert; Petan, Toni

2018-06-01

The data presented here is related to the research article entitled "Lipid droplets induced by secreted phospholipase A 2 and unsaturated fatty acids protect breast cancer cells from nutrient and lipotoxic stress" by E. Jarc et al., Biochim. Biophys. Acta 1863 (2018) 247-265. Elevated uptake of unsaturated fatty acids and lipid droplet accumulation are characteristic of aggressive cancer cells and have been associated with the cellular stress response. The present study provides lipidomic data on the triacylglycerol (TAG) and phosphatidylcholine (PC) composition of MDA-MB-231 breast cancer cells exposed to docosahexaenoic acid (DHA; 22:6, ω-3). Datasets provide information on the changes in lipid composition induced by depletion of adipose triglyceride lipase (ATGL) and by exogenous addition of secreted phospholipase A 2 (sPLA 2 ) in DHA-treated cells. The presented alterations in lipid composition, mediated by targeting lipid droplet biogenesis and lipolysis, are associated with protection from lipotoxicity and allow further investigation into the role of lipid droplets in the resistance of cancer cells to lipotoxic stress.

Water Evaporation from Acoustically Levitated Aqueous Solution Droplets.

PubMed

Combe, Nicole A; Donaldson, D James

2017-09-28

We present a systematic study of the effect of solutes on the evaporation rate of acoustically levitated aqueous solution droplets by suspending individual droplets in a zero-relative humidity environment and measuring their size as a function of time. The ratios of the early time evaporation rates of six simple salts (NaCl, NaBr, NaNO 3 , KCl, MgCl 2 , CaCl 2 ) and malonic acid to that of water are in excellent agreement with predictions made by modifying the Maxwell equation to include the time-dependent water activity of the evaporating aqueous salt solution droplets. However, the early time evaporation rates of three ammonium salt solutions (NH 4 Cl, NH 4 NO 3 , (NH 4 ) 2 SO 4 ) are not significantly different from the evaporation rate of pure water. This finding is in accord with a previous report that ammonium sulfate does not depress the evaporation rate of its solutions, despite reducing its water vapor pressure, perhaps due to specific surface effects. At longer evaporation times, as the droplets approach crystallization, all but one (MgCl 2 ) of the solution evaporation rates are well described by the modified Maxwell equation.

Regulation of Lipid Droplet Size in Mammary Epithelial Cells by Remodeling of Membrane Lipid Composition—A Potential Mechanism

PubMed Central

Cohen, Bat-Chen; Shamay, Avi; Argov-Argaman, Nurit

2015-01-01

Milk fat globule size is determined by the size of its precursors—intracellular lipid droplets—and is tightly associated with its composition. We examined the relationship between phospholipid composition of mammary epithelial cells and the size of both intracellular and secreted milk fat globules. Primary culture of mammary epithelial cells was cultured in medium without free fatty acids (control) or with 0.1 mM free capric, palmitic or oleic acid for 24 h. The amount and composition of the cellular lipids and the size of the lipid droplets were determined in the cells and medium. Mitochondrial quantity and expression levels of genes associated with mitochondrial biogenesis and polar lipid composition were determined. Cells cultured with oleic and palmitic acids contained similar quantities of triglycerides, 3.1- and 3.8-fold higher than in controls, respectively (P < 0.0001). When cultured with oleic acid, 22% of the cells contained large lipid droplets (>3 μm) and phosphatidylethanolamine concentration was higher by 23 and 63% compared with that in the control and palmitic acid treatments, respectively (P < 0.0001). In the presence of palmitic acid, only 4% of the cells contained large lipid droplets and the membrane phosphatidylcholine concentration was 22% and 16% higher than that in the control and oleic acid treatments, respectively (P < 0.0001). In the oleic acid treatment, approximately 40% of the lipid droplets were larger than 5 μm whereas in that of the palmitic acid treatment, only 16% of the droplets were in this size range. Triglyceride secretion in the oleic acid treatment was 2- and 12-fold higher compared with that in the palmitic acid and control treatments, respectively. Results imply that membrane composition of bovine mammary epithelial cells plays a role in controlling intracellular and secreted lipid droplets size, and that this process is not associated with cellular triglyceride content. PMID:25756421

Design Concepts, Fabrication and Advanced Characterization Methods of Innovative Piezoelectric Sensors Based on ZnO Nanowires.

PubMed

Araneo, Rodolfo; Rinaldi, Antonio; Notargiacomo, Andrea; Bini, Fabiano; Pea, Marialilia; Celozzi, Salvatore; Marinozzi, Franco; Lovat, Giampiero

2014-12-08

Micro- and nano-scale materials and systems based on zinc oxide are expected to explode in their applications in the electronics and photonics, including nano-arrays of addressable optoelectronic devices and sensors, due to their outstanding properties, including semiconductivity and the presence of a direct bandgap, piezoelectricity, pyroelectricity and biocompatibility. Most applications are based on the cooperative and average response of a large number of ZnO micro/nanostructures. However, in order to assess the quality of the materials and their performance, it is fundamental to characterize and then accurately model the specific electrical and piezoelectric properties of single ZnO structures. In this paper, we report on focused ion beam machined high aspect ratio nanowires and their mechanical and electrical (by means of conductive atomic force microscopy) characterization. Then, we investigate the suitability of new power-law design concepts to accurately model the relevant electrical and mechanical size-effects, whose existence has been emphasized in recent reviews.

Design Concepts, Fabrication and Advanced Characterization Methods of Innovative Piezoelectric Sensors Based on ZnO Nanowires

PubMed Central

Araneo, Rodolfo; Rinaldi, Antonio; Notargiacomo, Andrea; Bini, Fabiano; Pea, Marialilia; Celozzi, Salvatore; Marinozzi, Franco; Lovat, Giampiero

2014-01-01

Micro- and nano-scale materials and systems based on zinc oxide are expected to explode in their applications in the electronics and photonics, including nano-arrays of addressable optoelectronic devices and sensors, due to their outstanding properties, including semiconductivity and the presence of a direct bandgap, piezoelectricity, pyroelectricity and biocompatibility. Most applications are based on the cooperative and average response of a large number of ZnO micro/nanostructures. However, in order to assess the quality of the materials and their performance, it is fundamental to characterize and then accurately model the specific electrical and piezoelectric properties of single ZnO structures. In this paper, we report on focused ion beam machined high aspect ratio nanowires and their mechanical and electrical (by means of conductive atomic force microscopy) characterization. Then, we investigate the suitability of new power-law design concepts to accurately model the relevant electrical and mechanical size-effects, whose existence has been emphasized in recent reviews. PMID:25494351

Characterization of Antimicrobial Poly (Lactic Acid)/Nano-Composite Films with Silver and Zinc Oxide Nanoparticles

PubMed Central

Chu, Zhuangzhuang; Zhao, Tianrui; Li, Lin; Fan, Jian; Qin, Yuyue

2017-01-01

Antimicrobial active films based on poly (lactic acid) (PLA) were prepared with nano-silver (nano-Ag) and nano-zinc oxide (nano-ZnO) using a solvent volatilizing method. The films were characterized for mechanical, structural, thermal, physical and antimicrobial properties. Scanning electron microscopy (SEM) images characterized the fracture morphology of the films with different contents of nano-Ag and nano-ZnO. The addition of nanoparticles into the pure PLA film decreased the tensile strength and elasticity modulus and increased the elongation of breaks—in other words, the flexibility and extensibility of these composites improved. According to the results of differential scanning calorimetry (DSC), the glass transition temperature of the PLA nano-composite films decreased, and the crystallinity of these films increased; a similar result was apparent from X-ray diffraction (XRD) analysis. The water vapor permeability (WVP) and opacity of the PLA nano-composite films augmented compared with pure PLA film. Incorporation of nanoparticles to the PLA films significantly improved the antimicrobial activity to inhibit the growth of Escherichia coli. The results indicated that PLA films with nanoparticles could be considered a potential environmental-friendly packaging material. PMID:28773018

Fullerene reinforced ionic polymer transducer

NASA Astrophysics Data System (ADS)

Jung, J. H.; Cheng, T. H.; Oh, I. K.

2009-07-01

Novel fullerene reinforced nano-composite transducers based on nafion were developed inorder to improve the ionic polymer metal composite transducer. The fullerene reinforced nano-composite membranes were fabricated by recasting method with 0.1 and 0.5 weight percentage of a Fullerenes. Stress-Strain tests showed tremendous increase in stiffness and modulus of the nano-composite membranes even at these minute concentrations of Fullerenes. Ionic exchange capacity analysis and proton conductivity test were performed to calculate the electrical property of the composite films. Water uptake was measured to understand the liquid adsorbing characteristics of the membranes. Also, tip displacement of the nano-composite membrane transducer was investigated under AC excitations with various magnitudes and frequencies. Furthermore, the generated energy was measured from external sinusoidal physical input vibration with several displacements and frequencies by using a mechanical shaker. As a result, the fullerene reinforced nanocomposite membrane based on nafion shows higher stiffness and Young's modulus than that of pure nafion membrane. Also, the nano-composite membrane had better water uptake and proton conductivity than the pure membrane. Fullerene reinforced nano-composite membrane transducer actuates to a much larger deformations than pure nafion membrane transducer. The developed membrane transducer dissipates more energy from the physical input vibration than that of unfilled(or virgin) Nafion membrane transducer.

The Effect of Nano Loading and Ultrasonic Compounding of EVA/LDPE/Nano-magnesium Hydroxide on Mechanical Properties and Distribution of Nano Particles

NASA Astrophysics Data System (ADS)

Azman, I. A.; Salleh, R. M.; Alauddin, S. M.; Shueb, M. I.

2018-05-01

Blends of Ethylene Vinyl Acetate (EVA) and Low-Density Polyethylene (LDPE) are promising composite which have good mechanical properties to environmental stress cracking. However, they lack fire resistant properties, which limits it usage in wire and cable industry. In order to improve flame retardancy ability, a range of nano-magnesium hydroxide (nano-MH) loading which is from 0 phr to maximum of 20 phr with ultrasonic extrusion 0-100 kHz frequencies have been introduced. Ultrasonic extrusion was used to improve the distribution of nano-MH. It was found that, 10 phr of nano loading with 100 kHz ultrasonic assisted has greater tensile strength compared to the nanocomposite without ultrasonication. Further increase of nano MH loading, will decrease the tensile properties. Better elongation at break was observed at10 phr nano-MH with the frequency of 50 kHz. The sample of 20 phr of nanoMH assisted with 50 kHz ultrasonic exhibits good flexural properties while 10 phr of nano-MH without the ultrasonic assisted demonstrates good in izod impact properties. From the evaluation of mechanical properties studied, it was found that 10 phr of nano-MH has shown the best performance among all the samples tested for EVA/LDPE/nano-MH composites. Transmission Electron Microscopy (TEM) has been conducted on 10 phr sample with different frequencies in order to observe the distribution of nano-MH particles. The sample with 100 kHz frequency shows more uniform dispersion of nano-MH in EVA/LDPE composites. This investigation indicates that the ultrasonic technology can enhance the mechanical properties studied as well as the dispersion of nano particles in the composite.

SIMULATION STUDIES OF THE WETTING OF CRYSTALLINE FACES OF COTTON CELLULOSE

USDA-ARS?s Scientific Manuscript database

Models of the surfaces of nano-sized cellulose crystals were constructed and a model droplet of water was placed on each. Then, the model atoms were given motion that corresponds to room temperature (a molecular dynamics simulation), and the spreading of the water over the surfaces was studied. Besi...

Nanotechnology: current uses and future applications in the food industry.

PubMed

Thiruvengadam, Muthu; Rajakumar, Govindasamy; Chung, Ill-Min

2018-01-01

Recent advances in nanoscience and nanotechnology intend new and innovative applications in the food industry. Nanotechnology exposed to be an efficient method in many fields, particularly the food industry and the area of functional foods. Though as is the circumstance with the growth of any novel food processing technology, food packaging material, or food ingredient, additional studies are needed to demonstrate the potential benefits of nanotechnologies and engineered nanomaterials designed for use in foods without adverse health effects. Nanoemulsions display numerous advantages over conventional emulsions due to the small droplets size they contain: high optical clarity, excellent physical constancy against gravitational partition and droplet accumulation, and improved bioavailability of encapsulated materials, which make them suitable for food applications. Nano-encapsulation is the most significant favorable technologies having the possibility to ensnare bioactive chemicals. This review highlights the applications of current nanotechnology research in food technology and agriculture, including nanoemulsion, nanocomposites, nanosensors, nano-encapsulation, food packaging, and propose future developments in the developing field of agrifood nanotechnology. Also, an overview of nanostructured materials, and their current applications and future perspectives in food science are also presented.

Selective intracellular vaporisation of antibody-conjugated phase-change nano-droplets in vitro

NASA Astrophysics Data System (ADS)

Ishijima, A.; Minamihata, K.; Yamaguchi, S.; Yamahira, S.; Ichikawa, R.; Kobayashi, E.; Iijima, M.; Shibasaki, Y.; Azuma, T.; Nagamune, T.; Sakuma, I.

2017-03-01

While chemotherapy is a major mode of cancer therapeutics, its efficacy is limited by systemic toxicities and drug resistance. Recent advances in nanomedicine provide the opportunity to reduce systemic toxicities. However, drug resistance remains a major challenge in cancer treatment research. Here we developed a nanomedicine composed of a phase-change nano-droplet (PCND) and an anti-cancer antibody (9E5), proposing the concept of ultrasound cancer therapy with intracellular vaporisation. PCND is a liquid perfluorocarbon nanoparticle with a liquid-gas phase that is transformable upon exposure to ultrasound. 9E5 is a monoclonal antibody targeting epiregulin (EREG). We found that 9E5-conjugated PCNDs are selectively internalised into targeted cancer cells and kill the cells dynamically by ultrasound-induced intracellular vaporisation. In vitro experiments show that 9E5-conjugated PCND targets 97.8% of high-EREG-expressing cancer cells and kills 57% of those targeted upon exposure to ultrasound. Furthermore, direct observation of the intracellular vaporisation process revealed the significant morphological alterations of cells and the release of intracellular contents.

Accounting for changes in particle charge, dry mass and composition occurring during studies of single levitated particles.

PubMed

Haddrell, Allen E; Davies, James F; Yabushita, Akihiro; Reid, Jonathan P

2012-10-11

The most used instrument in single particle hygroscopic analysis over the past thirty years has been the electrodynamic balance (EDB). Two general assumptions are made in hygroscopic studies involving the EDB. First, it is assumed that the net charge on the droplet is invariant over the time scale required to record a hygroscopic growth cycle. Second, it is assumed that the composition of the droplet is constant (aside from the addition and removal of water). In this study, we demonstrate that these assumptions cannot always be made and may indeed prove incorrect. The presence of net charge in the humidified vapor phase reduces the total net charge retained by the droplet over prolonged levitation periods. The gradual reduction in charge limits the reproducibility of hygroscopicity measurements made on repeated RH cycles with a single particle, or prolonged experiments in which the particle is held at a high relative humidity. Further, two contrasting examples of the influence of changes in chemical composition changes are reported. In the first, simple acid-base chemistry in the droplet leads to the irreversible removal of gaseous ammonia from a droplet containing an ammonium salt on a time scale that is shorter than the hygroscopicity measurement. In the second example, the net charge on the droplet (<100 fC) is high enough to drive redox chemistry within the droplet. This is demonstrated by the reduction of iodic acid in a droplet made solely of iodic acid and water to form iodine and an iodate salt.

Solution and interfacial behavior of modified silicone polymers and their interactions with solid substrates

NASA Astrophysics Data System (ADS)

Purohit, Parag

Surface treatment is very important step in many applications such as fabric finishing, coatings, cosmetics and personal care. Silicone polymers are a class of organic/inorganic materials that show unique properties such as weak intermolecular forces and high flexibility enabling even a very high molecular weight chain to achieve optimal orientation on surfaces. Material properties such as softness, repellency, bounciness and friction can therefore be tailored by using appropriately modified silicone polymers. Despite wide applications, the underlying mechanisms of material modification are unknown and tailoring silicones for applications remains mostly empirical. Thus the objective of this research is to understand the solution and interfacial behavior of functionalized silicone polymers, which govern their performance in material modification. Modified silicones are simultaneously hydrophobic and oleophobic in nature and due to this nearly universal non-compatibility, the studies of these polymers present unusual challenges. Due to this incompatible nature, the functionalized silicone polymers were emulsified into O/W emulsions to study their solution and interfacial properties. The colloidal properties such as electrokinetic and droplet distribution of these emulsions are assumed to play an important role in the observed surface and physical properties of solid substrates (in present study, cellulosic substrates) as well the stability of emulsions itself. To understand the effects of modified silicones on cellulosic substrates a variety of techniques such as frictional analysis, scanning electron microscopy and atomic force microscopy that can probe from macro to nano level were used. It is hypothesized that the size distribution and charge of silicone emulsions as well as the physiochemical conditions such as pH, control silicone conformation which in turn affect the modification of the substrate properties. With bimodal droplet distribution of silicone emulsions, the nano-sized droplets can penetrate deeper into the substrate to provide bounciness, whereas macro-sized droplets can coat the top layer leading to friction reduction. It was observed that at pH 5.5 the silicone treatment resulted in charge reversal of fibers as opposed to treatment at pH 9.5. On a macroscopic scale 20% reduction in frictional coefficient of the fabric was observed after treatment with quaternized (cationically modified) silicones as compared to untreated fibers. It was also observed using AFM that the fibrils treated with quaternized silicones are uniform, well stacked and smoother than the untreated fibers. Spectroscopic analysis of treated fibers using Raman spectroscopy indicated a decrease in fiber stress as a function of modification of silicone polymer and the interaction pH. It is concluded that the protonated amine functional silicone (below pH 7) as well as the quaternized silicone interacts with the negatively charged cellulose fibers primarily through electrostatic interactions. It is proposed that this initial surface coating is a uniform thin film which allows further deposition of polymer from the emulsion. It was observed that at high pH the zetapotential of silicone emulsions decreases drastically and the nano emulsions turn turbid. It is proposed that the observed electrophoretic and nephelometric behavior at high pH is due to flocculation of nanosized droplets to micron size, which eventually leads to droplets coalescing and emulsion destabilization. It is also postulated that the nano emulsion possess a critical dilution concentration (CDC), above which dilution leads to rapid coalescence. This critical dilution phase was further confirmed through polarity parameter and excimer formation studies which show significantly different polymer and surfactant microstructures near the CDC. Hence it is concluded that the observed surface properties of the substrate obtained above the CDC are significantly different than those below the CDC. The results reveal the vital role of physiochemical parameters such as pH, droplet size, and concentration on the emulsion stability as well as the observed physical/chemical properties of the substrates.

Fabrication of nano piezoelectric based vibration accelerometer for mechanical sensing

NASA Astrophysics Data System (ADS)

Murugan, S.; Prasad, M. V. N.; Jayakumar, K.

2016-05-01

An electromechanical sensor unit has been fabricated using nano PZT embedded in PVDF polymer. Such a polymer nano composite has been used as vibration sensor element and sensitivity, detection of mechanical vibration, and linearity measurements have been investigated. It is found from its performance, that this nano composite sensor is suitable for mechanical sensing applications.

Studies on Effective Elastic Properties of CNT/Nano-Clay Reinforced Polymer Hybrid Composite

NASA Astrophysics Data System (ADS)

Thakur, Arvind Kumar; Kumar, Puneet; Srinivas, J.

2016-02-01

This paper presents a computational approach to predict elastic propertiesof hybrid nanocomposite material prepared by adding nano-clayplatelets to conventional CNT-reinforced epoxy system. In comparison to polymers alone/single-fiber reinforced polymers, if an additional fiber is added to the composite structure, it was found a drastic improvement in resultant properties. In this regard, effective elastic moduli of a hybrid nano composite are determined by using finite element (FE) model with square representative volume element (RVE). Continuum mechanics based homogenization of the nano-filler reinforced composite is considered for evaluating the volumetric average of the stresses and the strains under different periodic boundary conditions.A three phase Halpin-Tsai approach is selected to obtain the analytical result based on micromechanical modeling. The effect of the volume fractions of CNTs and nano-clay platelets on the mechanical behavior is studied. Two different RVEs of nano-clay platelets were used to investigate the influence of nano-filler geometry on composite properties. The combination of high aspect ratio of CNTs and larger surface area of clay platelets contribute to the stiffening effect of the hybrid samples. Results of analysis are validated with Halpin-Tsai empirical formulae.

Magnetic droplet soliton nucleation in oblique fields

NASA Astrophysics Data System (ADS)

Mohseni, Morteza; Hamdi, M.; Yazdi, H. F.; Banuazizi, S. A. H.; Chung, S.; Sani, S. R.; Åkerman, Johan; Mohseni, Majid

2018-05-01

We study the auto-oscillating magnetodynamics in orthogonal spin-torque nano-oscillators (STNOs) as a function of the out-of-plane (OOP) magnetic-field angle. In perpendicular fields and at OOP field angles down to approximately 50°, we observe the nucleation of a droplet. However, for field angles below 50°, experiments indicate that the droplet gives way to propagating spin waves, in agreement with our micromagnetic simulations. Theoretical calculations show that the physical mechanism behind these observations is the sign changing of spin-wave nonlinearity (SWN) by angle. In addition, we show that the presence of a strong perpendicular magnetic anisotropy free layer in the system reverses the angular dependence of the SWN and dynamics in STNOs with respect to the known behavior determined for the in-plane magnetic anisotropy free layer. Our results are of fundamental interest in understanding the rich dynamics of nanoscale solitons and spin-wave dynamics in STNOs.

Mechanical properties and strengthening mechanism of epoxy resin reinforced with nano-SiO2 particles and multi-walled carbon nanotubes

NASA Astrophysics Data System (ADS)

Xiao, Chufan; Tan, Yefa; Yang, Xupu; Xu, Ting; Wang, Lulu; Qi, Zehao

2018-03-01

Nano-SiO2 particles and MWCNTs were used to reinforce the EPs. The mechanical properties of the composites and the strengthening mechanisms of nano-SiO2 and MWCNTs on the mechanical properties of epoxy composites were studied. The results show that the mechanical properties of the reinforced epoxy composites are greatly improved. Especially, nano-SiO2/MWCNTs/EP composites exhibit the most excellent mechanical properties. The synergistic strengthening mechanisms of nano-SiO2 and MWCNTs on the EP are the micro plastic deformation effect, micro-cracks and their divarication effect, and the pull-out effect of MWCNTs in EP matrix, which can reduce the extent of stress concentration and absorb more energy.

Structural and magnetic characteristics of PVA/CoFe{sub 2}O{sub 4} nano-composites prepared via mechanical alloying method

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

Rashidi, S.; Ataie, A., E-mail: aataie@ut.ac.ir

Highlights: • Single phase CoFe{sub 2}O{sub 4} nano-particles synthesized in one step by mechanical alloying. • PVA/CoFe{sub 2}O{sub 4} magnetic nano-composites were fabricated via mechanical milling. • FTIR confirmed the interaction between PVA and magnetic CoFe{sub 2}O{sub 4} particles. • Increasing in milling time and PVA amount led to well dispersion of CoFe{sub 2}O{sub 4}. - Abstract: In this research, polyvinyl alcohol/cobalt ferrite nano-composites were successfully synthesized employing a two-step procedure: the spherical single-phase cobalt ferrite of 20 ± 4 nm mean particle size was synthesized via mechanical alloying method and then embedded into polymer matrix by intensive milling. Themore » results revealed that increase in polyvinyl alcohol content and milling time causes cobalt ferrite particles disperse more homogeneously in polymer matrix, while the mean particle size and shape of cobalt ferrite have not been significantly affected. Transmission electron microscope images indicated that polyvinyl alcohol chains have surrounded the cobalt ferrite nano-particles; also, the interaction between polymer and cobalt ferrite particles in nano-composite samples was confirmed. Magnetic properties evaluation showed that saturation magnetization, coercivity and anisotropy constant values decreased in nano-composite samples compared to pure cobalt ferrite. However, the coercivity values of related nano-composite samples enhanced by increasing PVA amount due to domain wall mechanism.« less

[Study on biocompatibility of hydroxyapatite/high density polyethylene (HA/HDPE) nano-composites artificial ossicle].

PubMed

Wang, Guohui; Zhu, Shaihong; Tan, Guolin; Zhou, Kechao; Huang, Suping; Zhao, Yanzhong; Li, Zhiyou; Huang, Boyun

2008-06-01

This study was aimed to evaluate the biocompatibility of Hydroxyapatite/High density polyethylene (HA/ HDPE) nano-composites artificial ossicle. The percentage of S-period cells were detected by flow cytometry after L929 cells being incubated with extraction of the HA/HDPE nano-composites; the titanium materials for clinical application served as the contrast. In addition, both materials were implanted in animals and the histopathological evaluations were conducted. There were no statistically significant differences between the two groups (P >0.05). The results demonstrated that the HA/HDPE nano-composite artificial ossicle made by our laboratory is of a good biocompatibility and clinical application outlook.

On the Size Dependence of Molar and Specific Properties of Independent Nano-phases and Those in Contact with Other Phases

NASA Astrophysics Data System (ADS)

Kaptay, George

2018-05-01

Nano-materials are materials with at least one nano-phase. A nano-phase is a phase with at least one of its dimensions below 100 nm. It is shown here that nano-phases have at least 1% of their atoms along their surface layer. The ratio of surface atoms is proportional to the specific surface area of the phase, defined as the ratio of its surface area to its volume. Each specific/molar property has its bulk value and its surface value for the given phase, being always different, as the energetic states of the atoms in the bulk and in the surface layer of a phase are different. The average specific/molar property of a nano-phase is modeled here as a linear combination of the bulk and surface values of the same property, scaled with the ratio of the surface atoms. That makes the performance of all nano-phases proportional to their specific surface area. As the characteristic size of the nano-phase is inversely proportional to its specific surface area, all specific/molar properties of nano-phases are inversely proportional to the characteristic size of the phase. This is applied to the size dependence of the molar Gibbs energy of the nano-phase, which appears to be in agreement with the thermodynamics of Gibbs. This agreement proves the general validity of the present model on the size dependence of the specific/molar properties of independent nano-phases. It is shown that the properties of nano-phases are different for independent nano-phases (surrounded only by their equilibrium vapor phase) and for nano-phases in multi-phase situations, such as a liquid nano-droplet in the sessile drop configuration.

Effects of Nanoparticulate Additives on Acoustically Coupled Fuel Droplet Combustion

NASA Astrophysics Data System (ADS)

Vargas, Andres; Plascencia, Miguel; Sim, Hyung Sub; Smith, Owen; Karagozian, Ann

2017-11-01

The present study investigates interactions between applied acoustic perturbations and burning ethanol droplets containing nano particulate additives. Reactive nanoscale aluminum (nAl) as well as inert silica (nSiO2), each with an 80 nm average diameter. Continuously-fed fuel droplet combustion experiments were conducted in the vicinity of a pressure node created in a closed acoustic waveguide, with a range of applied forcing frequencies, pressure or velocity perturbation amplitudes, and particle loading concentrations. Simultaneous phase-locked OH* chemiluminescence and high-speed visible imaging enabled quantification of the influences of nanoparticle concentration on burning rate constant K and combustion-acoustic coupling. Results indicated that nAl particles in ethanol yielded measurable increases in K with increasing applied perturbation amplitudes, as compared to pure ethanol in the presence of acoustic excitation. Droplets with nAl exposed to moderate acoustic excitation exhibited sustained combustion for much longer periods of time than for unforced conditions. Post analysis of particulate matter collected from residue via electron microscopy aids in interpreting these trends and findings. Supported by AFOSR Grant FA9550-15-1-0339.

A review of nanoelectrospray ionization applications for drug metabolism and pharmacokinetics.

PubMed

Wickremsinhe, Enaksha R; Singh, Gurkeerat; Ackermann, Bradley L; Gillespie, Todd A; Chaudhary, Ajai K

2006-12-01

Although traditionally reserved for proteomic analysis, nanoESI has found increased use for small molecule applications related to drug metabolism/pharmacokinetics (DMPK). NanoESI, which refers to ESI performed at flow rates in the range of 200 to 1000 nL/min using smaller diameter emitters (10 to 100 microm id), produces smaller droplets than conventional ESI resulting in more efficient ionization. Benefits include greater sensitivity, enhanced dynamic range, and a reduced competition for ionization. These advantages may now be harnessed largely due to the introduction of a commercial system for automated nanoESI infusion. This development in turn has allowed ADME (absorption, distribution, metabolism, and excretion) scientists to consider novel approaches to mass spectrometric analysis without direct LC interfacing. While it is freely acknowledged that nanoESI infusion is not likely to supplant LC-MS as the primary analytical platform for ADME, nanoESI infusion has been successfully applied to both quantitative (bioanalysis) and qualitative (metabolite identification) applications. This review summarizes published applications of this technology and offers a perspective on where it fits best into the DMPK laboratory.

Design of ice-free nanostructured surfaces based on repulsion of impacting water droplets.

PubMed

Mishchenko, Lidiya; Hatton, Benjamin; Bahadur, Vaibhav; Taylor, J Ashley; Krupenkin, Tom; Aizenberg, Joanna

2010-12-28

Materials that control ice accumulation are important to aircraft efficiency, highway and powerline maintenance, and building construction. Most current deicing systems include either physical or chemical removal of ice, both energy and resource-intensive. A more desirable approach would be to prevent ice formation rather than to fight its build-up. Much attention has been given recently to freezing of static water droplets resting on supercooled surfaces. Ice accretion, however, begins with the droplet/substrate collision followed by freezing. Here we focus on the behavior of dynamic droplets impacting supercooled nano- and microstructured surfaces. Detailed experimental analysis of the temperature-dependent droplet/surface interaction shows that highly ordered superhydrophobic materials can be designed to remain entirely ice-free down to ca. -25 to -30 °C, due to their ability to repel impacting water before ice nucleation occurs. Ice accumulated below these temperatures can be easily removed. Factors contributing to droplet retraction, pinning and freezing are addressed by combining classical nucleation theory with heat transfer and wetting dynamics, forming the foundation for the development of rationally designed ice-preventive materials. In particular, we emphasize the potential of hydrophobic polymeric coatings bearing closed-cell surface microstructures for their improved mechanical and pressure stability, amenability to facile replication and large-scale fabrication, and opportunities for greater tuning of their material and chemical properties.

Role of red cells and plasma composition on blood sessile droplet evaporation

NASA Astrophysics Data System (ADS)

Lanotte, Luca; Laux, Didier; Charlot, Benoît; Abkarian, Manouk

2017-11-01

The morphology of dried blood droplets derives from the deposition of red cells, the main components of their solute phase. Up to now, evaporation-induced convective flows were supposed to be at the base of red cell distribution in blood samples. Here, we present a direct visualization by videomicroscopy of the internal dynamics in desiccating blood droplets, focusing on the role of cell concentration and plasma composition. We show that in diluted suspensions, the convection is promoted by the rich molecular composition of plasma, whereas it is replaced by an outward red blood cell displacement front at higher hematocrits. We also evaluate by ultrasounds the effect of red cell deposition on the temporal evolution of sample rigidity and adhesiveness.

Facile fabrication and characterization of poly(tetrafluoroethylene)@polypyrrole/nano-silver composite membranes with conducting and antibacterial property

NASA Astrophysics Data System (ADS)

Shi, Zhiquan; Zhou, Hui; Qing, Xutang; Dai, Tingyang; Lu, Yun

2012-06-01

Porous poly(tetrafluoroethylene) (PTFE) membranes play an important role in air purification and separation engineering. To achieve the bi-functionality of conducting and antibacterial property, two kinds of poly(tetrafluoroethylene)@ polypyrrole/nano-silver composite membranes have been prepared. One involves hydrophobic polypyrrole/nano-silver composite with hollow capsule nanostructures immobilized on the surface of the PTFE membranes. The other is a type of composite membranes with polypyrrole/nano-silver composite wholly packed on the fibrils of the expand PTFE membrane to form core/shell coaxial cable structures. The structure and morphology of the two kinds of composite membranes have been characterized by FTIR, UV-vis, XRD, TGA and SEM measurements. Possible formation mechanisms of the hollow capsules and the core/shell nanocable structures have been discussed in detail. The antibacterial effects of composite membranes are also briefly investigated.

3-dimensional free standing micro-structures by proton beam writing of Su 8-silver nanoParticle polymeric composite

NASA Astrophysics Data System (ADS)

Igbenehi, H.; Jiguet, S.

2012-09-01

Proton beam lithography a maskless direct-write lithographic technique (well suited for producing 3-Dimensional microstructures in a range of resist and semiconductor materials) is demonstrated as an effective tool in the creation of electrically conductive freestanding micro-structures in an Su 8 + Nano Silver polymer composite. The structures produced show non-ohmic conductivity and fit the percolation theory conduction model of tunneling of separated nanoparticles. Measurements show threshold switching and a change in conductivity of at least 4 orders of magnitude. The predictable range of protons in materials at a given energy is exploited in the creation of high aspect ratio, free standing micro-structures, made from a commercially available SU8 Silver nano-composite (GMC3060 form Gersteltec Inc. a negative tone photo-epoxy with added metallic nano-particles(Silver)) to create films with enhanced electrical properties when exposed and cured. Nano-composite films are directly written on with a finely focused MeV accelerated Proton particle beam. The energy loss of the incident proton beams in the target polymer nano- composite film is concentrated at the end of its range, where damage occurs; changing the chemistry of the nano-composite film via an acid initiated polymerization - creating conduction paths. Changing the energy of the incident beams provide exposed regions with different penetration and damage depth - exploited in the demonstrated cantilever microstructure.

Effect of graphene oxide nano filler on dynamic behaviour of GFRP composites

NASA Astrophysics Data System (ADS)

Pujar, Nagabhushan V.; Nanjundaradhya, N. V.; Sharma, Ramesh S.

2018-04-01

Nano fillers like Alumina oxide, Titanium oxide, Carbon nano tube, Nano clay have been used to improve the mechanical and damping properties of fiber reinforced polymer composites. In the recent years Graphene oxide nano filler is receiving considerable attention for its outstanding properties. Literature available shows that Graphene oxide nano filler can be used to improve the mechanical properties. The use of Graphene oxide in vibration attenuation by enhancing the passive damping in fiber reinforced polymer composite has not been fully explored. The objective of this work is to investigate the dynamic behaviour of Glass fiber-reinforced composite embedded with Graphene oxide nano filler. Graphene oxide is dispersed in epoxy resin with various concentration (0.1%, 0.5% and 1%wt) using ultra-sonification process. Composite laminates were made using the traditional hand-lay-up followed by vacuum bag process. Experimental modal analysis using traditional `strike method' is used to evaluate modal parameters using FFT analyzer and Data Acquisition System. Experiments were carried out for two different fiber orientations viz 0 ➙ & 45 ➙ and two boundary conditions (Free-Free and Cantilever). The modal parameters such as natural frequency, mode shape, damping ratio were studied. This research work demonstrates the vibration damping behaviour with incorporation of Graphene oxide and provides a basic understanding of the damping characteristics in design and manufacture of high performance composites.

Fabrication of nano-Fe3O4 3D structure on carbon fibers as a microwave absorber and EMI shielding composite by modified EPD method

NASA Astrophysics Data System (ADS)

Gholampoor, Mahdi; Movassagh-Alanagh, Farid; Salimkhani, Hamed

2017-02-01

Recently, electromagnetic interference (EMI) shielding materials have absorbed a lot of attention due to a growing need for application in the area of electronic and wireless devices. In this study, a carbon-based EMI shielding composite was fabricated by electrophoretic deposition of Fe3O4 nano-particles on carbon fibers (CFs) as a 3D structure incorporated with an epoxy resin. Co-precipitation method was employed to synthesize Fe3O4 nano-particles. This as-synthesized Fe3O4 nano-powder was then successfully deposited on CFs using a modified multi-step electrophoretic deposition (EPD) method. The results of structural studies showed that the Fe3O4 nano-particles (25 nm) were successfully and uniformly deposited on CFs. The measured magnetic properties of as-synthesized Fe3O4 nano-powder and nano-Fe3O4/CFs composite showed that the saturation magnetization of bare Fe3O4 was decreased from Ms = 72.3 emu/g to Ms = 33.1 emu/g for nano-Fe3O4/CFs composite and also corecivity of Fe3O4 was increased from Hc = 4.9 Oe to Hc = 168 Oe for composite. The results of microwave absorption tests revealed that the reflection loss (RL) of an epoxy-based nano-Fe3O4/CFs composite are significantly influenced by layer thickness. The maximum RL value of -10.21 dB at 10.12 GHz with an effective absorption bandwidth about 2 GHz was obtained for the sample with the thickness of 2 mm. It also exhibited an EMI shielding performance of -23 dB for whole the frequency range of 8.2-12.4 GHz.

Dancing droplets: Contact angle, drag, and confinement

NASA Astrophysics Data System (ADS)

Benusiglio, Adrien; Cira, Nate; Prakash, Manu

2015-11-01

When deposited on a clean glass slide, a mixture of water and propylene glycol forms a droplet of given contact angle, when both pure liquids spread. (Cira, Benusiglio, Prakash: Nature, 2015). The droplet is stabilized by a gradient of surface tension due to evaporation that induces a Marangoni flow from the border to the apex of the droplets. The apparent contact angle of the droplets depends on both their composition and the external humidity as captured by simple models. These droplets present remarkable properties such as lack of a large pinning force. We discuss the drag on these droplets as a function of various parameters. We show theoretical and experimental results of how various confinement geometries change the vapor gradient and the dynamics of droplet attraction.

Thermoelectric properties of SrTiO3 nano-particles dispersed indium selenide bulk composites

NASA Astrophysics Data System (ADS)

Lee, Min Ho; Rhyee, Jong-Soo; Vaseem, Mohammad; Hahn, Yoon-Bong; Park, Su-Dong; Jin Kim, Hee; Kim, Sung-Jin; Lee, Hyeung Jin; Kim, Chilsung

2013-06-01

We investigated the thermoelectric properties of the InSe, InSe/In4Se3 composite, and SrTiO3 (STO) nano-particles dispersed InSe/In4Se3 bulk composites. The electrical conductivity of the InSe/In4Se3 composite with self-assembled phase separation is significantly increased compared with those of InSe and In4Se3-δ implying the enhancement of surface conductivity between grain boundaries. The thermal conductivity of InSe/In4Se3 composite is decreased compared to those of InSe. When the STO nano-particle dispersion was employed in the InSe/In4Se3 composite, a coherent interface was observed between nano-particle precipitates and the InSe bulk matrix with a reduction of the thermal conductivity.

Thermal Conductivity Measurement of Molten Cu-Co Alloy Using an Electromagnetic Levitator Superimposed with a Static Magnetic Field

NASA Astrophysics Data System (ADS)

Nakamura, Yuki; Takahashi, Ryuji; Shoji, Eita; Kubo, Masaki; Tsukada, Takao; Uchikoshi, Masahito; Fukuyama, Hiroyuki

2017-12-01

The thermal conductivity of molten Cu-Co alloy with different compositions around the liquidus line temperature was measured by the periodic laser-heating method using an electromagnetic levitator superimposed with a static magnetic field to suppress convection in a levitated droplet sample. During the measurement, a static magnetic field of 10 T was applied to the levitated droplet. To confirm that the strength of the static magnetic field was sufficient to suppress convection in the droplet, numerical simulations were performed for the flow and thermal fields in an electromagnetically levitated droplet under a static magnetic field, and moreover, for the periodic laser-heating method to determine the thermal conductivity. It was found that the thermal conductivity of molten Cu-Co alloy increased gradually with increasing Cu composition up to 80 at. pct, beyond which it increased markedly and reached that of pure Cu. In addition, it was found that the composition dependence of the thermal conductivity can be explainable by the Wiedemann-Franz law.

Preparation of biocompatible magnetite-carboxymethyl cellulose nanocomposite: characterization of nanocomposite by FTIR, XRD, FESEM and TEM.

PubMed

Habibi, Neda

2014-10-15

The preparation and characterization of magnetite-carboxymethyl cellulose nano-composite (M-CMC) material is described. Magnetite nano-particles were synthesized by a modified co-precipitation method using ferrous chloride tetrahydrate and ferric chloride hexahydrate in ammonium hydroxide solution. The M-CMC nano-composite particles were synthesized by embedding the magnetite nanoparticles inside carboxymethyl cellulose (CMC) using a freshly prepared mixture of Fe3O4 with CMC precursor. Morphology, particle size, and structural properties of magnetite-carboxymethyl cellulose nano-composite was accomplished using X-ray powder diffraction (XRD), transmission electron microscopy (TEM), Fourier transformed infrared (FTIR) and field emission scanning electron microscopy (FESEM) analysis. As a result, magnetite nano-particles with an average size of 35nm were obtained. The biocompatible Fe3O4-carboxymethyl cellulose nano-composite particles obtained from the natural CMC polymers have a potential range of application in biomedical field. Copyright © 2014 Elsevier B.V. All rights reserved.

Precise, contactless measurements of the surface tension of picolitre aerosol droplets† †Electronic supplementary information (ESI) available: Parametrizations used to infer concentration, density, viscosity, and surface tension from refractive index for sodium chloride and glutaric acid; description of the semi-analytical T-matrix calculations; Fig. S1 and S2. See DOI: 10.1039/c5sc03184b Click here for additional data file.

PubMed Central

Bzdek, Bryan R.; Power, Rory M.; Simpson, Stephen H.; Royall, C. Patrick

2016-01-01

The surface composition and surface tension of aqueous droplets can influence key aerosol characteristics and processes including the critical supersaturation required for activation to form cloud droplets in the atmosphere. Despite its fundamental importance, surface tension measurements on droplets represent a considerable challenge owing to their small volumes. In this work, we utilize holographic optical tweezers to study the damped surface oscillations of a suspended droplet (<10 μm radius) following the controlled coalescence of a pair of droplets and report the first contactless measurements of the surface tension and viscosity of droplets containing only 1–4 pL of material. An advantage of performing the measurement in aerosol is that supersaturated solute states (common in atmospheric aerosol) may be accessed. For pairs of droplets starting at their equilibrium surface composition, surface tensions and viscosities are consistent with bulk equilibrium values, indicating that droplet surfaces respond to changes in surface area on microsecond timescales and suggesting that equilibrium values can be assumed for growing atmospheric droplets. Furthermore, droplet surfaces are shown to be rapidly modified by trace species thereby altering their surface tension. This equilibration of droplet surface tension to the local environmental conditions is illustrated for unknown contaminants in laboratory air and also for droplets exposed to gas passing through a water–ethanol solution. This approach enables precise measurements of surface tension and viscosity over long time periods, properties that currently are poorly constrained. PMID:28758004

Study on preparation of SnO2-TiO2/Nano-graphite composite anode and electro-catalytic degradation of ceftriaxone sodium.

PubMed

Guo, Xiaolei; Wan, Jiafeng; Yu, Xiujuan; Lin, Yuhui

2016-12-01

In order to improve the electro-catalytic activity and catalytic reaction rate of graphite-like material, Tin dioxide-Titanium dioxide/Nano-graphite (SnO 2 -TiO 2 /Nano-G) composite was synthesized by a sol-gel method and SnO 2 -TiO 2 /Nano-G electrode was prepared in hot-press approach. The composite was characterized by X-ray photoelectron spectroscopy, fourier transform infrared, Raman, N 2 adsorption-desorption, scanning electrons microscopy, transmission electron microscopy and X-ray diffraction. The electrochemical performance of the SnO 2 -TiO 2 /Nano-G anode electrode was investigated via cyclic voltammetry and electrochemical impedance spectroscopy. The electro-catalytic performance was evaluated by the degradation of ceftriaxone sodium and the yield of ·OH radicals in the reaction system. The results demonstrated that TiO 2 , SnO 2 and Nano-G were composited successfully, and TiO 2 and SnO 2 particles dispersed on the surface and interlamination of the Nano-G uniformly. The specific surface area of SnO 2 modified anode was higher than that of TiO 2 /Nano-G anode and the degradation rate of ceftriaxone sodium within 120 min on SnO 2 -TiO 2 /Nano-G electrode was 98.7% at applied bias of 2.0 V. The highly efficient electro-chemical property of SnO 2 -TiO 2 /Nano-G electrode was attributed to the admirable conductive property of the Nano-G and SnO 2 -TiO 2 /Nano-G electrode. Moreover, the contribution of reactive species ·OH was detected, indicating the considerable electro-catalytic activity of SnO 2 -TiO 2 /Nano-G electrode. Copyright © 2016 Elsevier Ltd. All rights reserved.

Volatility of organic aerosol: evaporation of ammonium sulfate/succinic acid aqueous solution droplets.

PubMed

Yli-Juuti, Taina; Zardini, Alessandro A; Eriksson, Axel C; Hansen, Anne Maria K; Pagels, Joakim H; Swietlicki, Erik; Svenningsson, Birgitta; Glasius, Marianne; Worsnop, Douglas R; Riipinen, Ilona; Bilde, Merete

2013-01-01

Condensation and evaporation modify the properties and effects of atmospheric aerosol particles. We studied the evaporation of aqueous succinic acid and succinic acid/ammonium sulfate droplets to obtain insights on the effect of ammonium sulfate on the gas/particle partitioning of atmospheric organic acids. Droplet evaporation in a laminar flow tube was measured in a Tandem Differential Mobility Analyzer setup. A wide range of droplet compositions was investigated, and for some of the experiments the composition was tracked using an Aerosol Mass Spectrometer. The measured evaporation was compared to model predictions where the ammonium sulfate was assumed not to directly affect succinic acid evaporation. The model captured the evaporation rates for droplets with large organic content but overestimated the droplet size change when the molar concentration of succinic acid was similar to or lower than that of ammonium sulfate, suggesting that ammonium sulfate enhances the partitioning of dicarboxylic acids to aqueous particles more than currently expected from simple mixture thermodynamics. If extrapolated to the real atmosphere, these results imply enhanced partitioning of secondary organic compounds to particulate phase in environments dominated by inorganic aerosol.

Volatility of Organic Aerosol: Evaporation of Ammonium Sulfate/Succinic Acid Aqueous Solution Droplets

PubMed Central

2013-01-01

Condensation and evaporation modify the properties and effects of atmospheric aerosol particles. We studied the evaporation of aqueous succinic acid and succinic acid/ammonium sulfate droplets to obtain insights on the effect of ammonium sulfate on the gas/particle partitioning of atmospheric organic acids. Droplet evaporation in a laminar flow tube was measured in a Tandem Differential Mobility Analyzer setup. A wide range of droplet compositions was investigated, and for some of the experiments the composition was tracked using an Aerosol Mass Spectrometer. The measured evaporation was compared to model predictions where the ammonium sulfate was assumed not to directly affect succinic acid evaporation. The model captured the evaporation rates for droplets with large organic content but overestimated the droplet size change when the molar concentration of succinic acid was similar to or lower than that of ammonium sulfate, suggesting that ammonium sulfate enhances the partitioning of dicarboxylic acids to aqueous particles more than currently expected from simple mixture thermodynamics. If extrapolated to the real atmosphere, these results imply enhanced partitioning of secondary organic compounds to particulate phase in environments dominated by inorganic aerosol. PMID:24107221

Ultra-low temperature curable nano-silver conductive adhesive for piezoelectric composite material

NASA Astrophysics Data System (ADS)

Yan, Chao; Liao, Qingwei; Zhou, Xingli; Wang, Likun; Zhong, Chao; Zhang, Di

2018-01-01

Limited by the low thermal resistance of composite material, ultra-low temperature curable conductive silver adhesive with curing temperature less than 100 °C needed urgently for the surface conduction treatment of piezoelectric composite material. An ultra-low temperature curable nano-silver conductive adhesive with high adhesion strength for the applications of piezoelectric composite material was investigated. The crystal structure of cured adhesive, SEM/EDS analysis, thermal analysis, adhesive properties and conductive properties of different content of nano-silver filler or micron-silver doping samples were studied. The results show that with 60 wt.% nano-silver filler the ultra-low temperature curable conductive silver adhesive had the relatively good conductivity as volume resistivity of 2.37 × 10-4 Ω cm, and good adhesion strength of 5.13 MPa. Minor micron-doping (below 15 wt.%) could improve conductivity, but would decrease other properties. The ultra-low temperature curable nano-silver conductive adhesive could successfully applied to piezoelectric composite material.

Study on dielectric and piezoelectric properties of 0.7 Pb(Mg1/3Nb2/3)O3-0.3 PbTiO3 single crystal with nano-patterned composite electrode

PubMed Central

Chang, Wei-Yi; Huang, Wenbin; Bagal, Abhijeet; Chang, Chih-Hao; Tian, Jian; Han, Pengdi; Jiang, Xiaoning

2013-01-01

Effect of nano-patterned composite electrode and backswitching poling technique on dielectric and piezoelectric properties of 0.7 Pb(Mg1/3Nb2/3)O3-0.3 PbTiO3 was studied in this paper. Composite electrode consists of Mn nano-patterns with pitch size of 200 nm, and a blanket layer of Ti/Au was fabricated using a nanolithography based lift-off process, heat treatment, and metal film sputtering. Composite electrode and backswitching poling resulted in 27% increase of d33 and 25% increase of dielectric constant, and we believe that this is attributed to regularly defined nano-domains and irreversible rhombohedral to monoclinic phase transition in crystal. The results indicate that nano-patterned composite electrode and backswitching poling has a great potential in domain engineering of relaxor single crystals for advanced devices. PMID:24170960

Lithography-free nanofluidic concentrator based on droplets-on-demand system

NASA Astrophysics Data System (ADS)

Yu, Miao; Zhou, Hongbo; Yao, Shuhuai

2013-11-01

Biomarkers are usually low-abundance proteins in biofluids and below detection limit of conventional biosensors. Nanofluidic concentration devices allow efficient biomolecules trapping by utilizing ion concentration polarization near nanochannels. However, once the electric field is turned off, the electrokinetic concentration plug cannot maintain its concentration status and starts to diffuse. In order to maintain the high concentration and extract the concentrated sample for further analysis, a good approach is to encapsulate these plugs into water-in-oil droplets. Here we developed a nanofluidic concentrator based on droplet-on-demand generator to encapsulate concentrated sample in nL droplets. The lithography-free nanochannels were patterned by thermal cracking on the surface of PS Petri-dish. The resulting nanochannel arrays were 30 nm in depth. In combination with microchannels on PDMS, the micro-nano hybrid chip was developed. We used FITC solution to demonstrate that the chip significantly increased the sample concentration for more than 100 folds within 5 minutes. By tuning the pulsed pressure imposed by the solenoid valve connected to the concentration channel, the system can generate a desired volume of droplet with a target sample concentration at a prescribed time. This work was supported by the Research Grants Council of Hong Kong under General Research Fund (Grant No. 621110).

Suppression of coffee ring: (Particle) size matters

NASA Astrophysics Data System (ADS)

Bansal, Lalit; Seth, Pranjal; Murugappan, Bhubesh; Basu, Saptarshi

2018-05-01

Coffee ring patterns in drying sessile droplets are undesirable in various practical applications. Here, we experimentally demonstrate that on hydrophobic substrates, the coffee ring can be suppressed just by increasing the particle diameter. Particles with larger size flocculate within the evaporation timescale, leading to a significant gravimetric settling (for Pe > 1) triggering a uniform deposit. Interestingly, the transition to a uniform deposit is found to be independent of the internal flow field and substrate properties. Flocculation of particles also alters the particle packing at the nanoscale resulting in order to disorder transitions. In this letter, we exhibit a physical exposition on how particle size affects morphodynamics of the droplet drying at macro-nano length scales.

Single-layer nano-carbon film, diamond film, and diamond/nano-carbon composite film field emission performance comparison

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

Wang, Xiaoping, E-mail: wxpchina64@aliyun.com, E-mail: wxpchina@sohu.com; Shanghai Key Laboratory of Modern Optical System, Shanghai 200093; Wang, Jinye

A series of single-layer nano-carbon (SNC) films, diamond films, and diamond/nano-carbon (D/NC) composite films have been prepared on the highly doped silicon substrate by using microwave plasma chemical vapor deposition techniques. The films were characterised by scanning electron microscopy, Raman spectroscopy, and field emission I-V measurements. The experimental results indicated that the field emission maximum current density of D/NC composite films is 11.8–17.8 times that of diamond films. And the field emission current density of D/NC composite films is 2.9–5 times that of SNC films at an electric field of 3.0 V/μm. At the same time, the D/NC composite film exhibitsmore » the advantage of improved reproducibility and long term stability (both of the nano-carbon film within the D/NC composite cathode and the SNC cathode were prepared under the same experimental conditions). And for the D/NC composite sample, a high current density of 10 mA/cm{sup 2} at an electric field of 3.0 V/μm was obtained. Diamond layer can effectively improve the field emission characteristics of nano-carbon film. The reason may be due to the diamond film acts as the electron acceleration layer.« less

Co-precipitation synthesis of nano-composites consists of zinc and tin oxides coatings on glass with enhanced photocatalytic activity on degradation of Reactive Blue 160 KE2B.

PubMed

Habibi, Mohammad Hossein; Mardani, Maryam

2015-02-25

Nano-composite containing zinc oxide-tin oxide was obtained by a facile co-precipitation route using tin chloride tetrahydrate and zinc chloride as precursors and coated on glass by Doctor Blade deposition. The crystalline structure and morphology of composites were evaluated by X-ray diffraction (XRD) and field emission scanning electron microscopy (FESEM). The XRD results showed peaks relative to zinc oxide with hexagonal wurtzite structure and tin oxide with tetragonal structure. FESEM observations showed that the nano-composite consisted of aggregates of particles with an average particle size of 18 nm. The photocatalytic activity of the pure SnO2, pure ZnO, ZnSnO3-Zn2SnO4 and ZnO-SnO2 nano-structure thin films was examined using the degradation of a textile dye Reactive Blue 160 (KE2B). ZnO-SnO2 nano-composite showed enhanced photo-catalytic activity than the pure zinc oxide and tin oxide. The enhanced photo-catalytic activity of the nano-composite was ascribed to an improved charge separation of the photo-generated electron-hole pairs. Copyright © 2014 Elsevier B.V. All rights reserved.

[Study on preparation of composite nano-scale Fe3O4 for phosphorus control].

PubMed

Li, Lei; Pan, Gang; Chen, Hao

2010-03-01

Composite nano-scale Fe3O4 particles were prepared in sodium carboxymethyl cellulose (CMC) solution by the oxidation deposition method. The adsorptions of phosphorus by micro-scale Fe3O4 and composite nano-scale Fe3O4 were investigated in water and soil, and the role of cellulase in the adsorption of composite nano-scale Fe3O4 was studied. Kinetic tests indicated that the equilibrium adsorption capacity of phosphorous on the composite nano-scale Fe3O4 (2.1 mg/g) was less than that of micro-scale Fe3O4 (3.2 mg/g). When cellulase was added to the solution of composite nano-scale Fe3O4 to degrade CMC, the removal rate of P by the nanoparticles (86%) was enhanced to the same level as the microparticles (90%). In the column tests, when the composite nano-scale Fe3O4 suspension was introduced in the downflow mode through the soil column, 72% of Fe3O4 penetrated through the soil bed under gravity. In contrast, the micro-scale Fe3O4 failed to pass through the soil column. The retention rate of P was 45% in the soil column when treated by the CMC-stabilized nanoparticles, in comparison with only 30% for the untreated soil column, however it could be improved to 74% in the soil column when treated by both the CMC-stabilized nanoparticles and cellulase, which degraded CMC after the nanoparticles were delivered into the soil.

A review of mechanical and tribological behaviour of polymer composite materials

NASA Astrophysics Data System (ADS)

Prabhakar, K.; Debnath, S.; Ganesan, R.; Palanikumar, K.

2018-04-01

Composite materials are finding increased applications in many industrial applications. A nano-composite is a matrix to which nanosized particles have been incorporated to drastically improve the mechanical performance of the original material. The structural components produced using nano-composites will exhibit a high strength-to-weight ratio. The properties of nano-composites have caused researchers and industries to consider using this material in several fields. Polymer nanocomposites consists of a polymer material having nano-particles or nano-fillers dispersed in the polymer matrix which may be of different shapes with at least one of the dimensions less than 100nm. In this paper, comprehensive review of polymer nanocomposites was done majorly in three different areas. First, mechanical behaviour of polymer nanocomposites which focuses on the mechanical property evaluation such as tensile strength, impact strength and modulus of elasticity based on the different combination of filler materials and nanoparticle inclusion. Second, wear behavior of Polymer composite materials with respect to different impingement angles and variation of filler composition using different processing techniques. Third, tribological (Friction and Wear) behaviour of nanocomposites using various combination of nanoparticle inclusion and time. Finally, it summarized the challenges and prospects of polymer nanocomposites.

a Study of Composite Coatings on 22MnCrNiMo Steel for Mooring Chain

NASA Astrophysics Data System (ADS)

Shen, Yan; Sahoo, Prasanta K.; Pan, Yipeng

In order to enhance the corrosion resistance of mooring chain, the composite coatings are carried out on the surface of 22MnCrNiMo steel for mooring chain by double-pulsed electrodeposition technology using centrifugal force in the rotating device. The microstructure and anti-corrosion performance of the composite coatings have been investigated experimentally. This paper mainly focuses on the experimental work to determine the structural characteristics and corrosion resistance of composite coatings in the presence of nano-SiC. The results show that the presence of nano-SiC has a significant effect on the preparation of composite coating during the process. The surface of the coating becomes compact and smooth at a moderate concentration of nano-SiC particles. Furthermore, the best corrosion resistance of the composite coatings can be obtained when the concentration of nano-SiC particles is 2.0g.L-1 after salt spray treatment.

Fiber-Reinforced Reactive Nano-Epoxy Composites

NASA Technical Reports Server (NTRS)

Zhong, Wei-Hong

2011-01-01

An ultra-high-molecular-weight polyethylene/ matrix interface based on the fabrication of a reactive nano-epoxy matrix with lower surface energy has been improved. Enhanced mechanical properties versus pure epoxy on a three-point bend test include: strength (25 percent), modulus (20 percent), and toughness (30 percent). Increased thermal properties include higher Tg (glass transition temperature) and stable CTE (coefficient of thermal expansion). Improved processability for manufacturing composites includes faster wetting rates on macro-fiber surfaces, lower viscosity, better resin infusion rates, and improved rheological properties. Improved interfacial adhesion properties with Spectra fibers by pullout tests include initial debonding force of 35 percent, a maximum pullout force of 25 percent, and energy to debond at 65 percent. Improved mechanical properties of Spectra fiber composites (tensile) aging resistance properties include hygrothermal effects. With this innovation, high-performance composites have been created, including carbon fibers/nano-epoxy, glass fibers/nano-epoxy, aramid fibers/ nano-epoxy, and ultra-high-molecularweight polyethylene fiber (UHMWPE).

Superconducting properties of Nb-Cu nano-composites and nano-alloys

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

Parab, Pradnya, E-mail: pradnyaprb@gmail.com; Kumar, Sanjeev; Bhui, Prabhjyot

The evolution of the superconducting transition temperature (T{sub c}) in nano-composite and nano-alloys of Nb-Cu, grown by DC magnetron co-sputtering are investigated. Microstructure of these films depends less strongly on the ratio of Nb:Cu but more on the growth temperature. At higher growth temperature, phase separated granular films of Nb and Cu were formed which showed superconducting transition temperatures (T{sub c}) of ~ 7.2±0.5 K, irrespective of the composition. Our results show that this is primarily influenced by the microstructure of the films determined during growth which rules out the superconducting proximity effect expected in these systems. At room temperaturemore » growth, films with nano-scale alloying were obtained at the optimal compositional range of 45-70 atomic% (At%) of Nb. These were also superconducting with a T{sub c} of 3.2 K.« less

Preparation and mechanical properties of photo-crosslinked poly(trimethylene carbonate) and nano-hydroxyapatite composites.

PubMed

Geven, Mike A; Barbieri, Davide; Yuan, Huipin; de Bruijn, Joost D; Grijpma, Dirk W

2015-01-01

Composite materials of photo-crosslinked poly(trimethylene carbonate) and nanoscale hydroxyapatite were prepared and their mechanical characteristics for application as orbital floor implants were assessed. The composites were prepared by solvent casting poly(trimethylene carbonate) macromers with varying amounts of nano-hydroxyapatite and subsequent photo-crosslinking. The incorporation of the nano-hydroxyapatite into the composites was examined by thermogravimetric analysis, scanning electron microscopy and gel content measurements. The mechanical properties were investigated by tensile testing and trouser tearing experiments. Our results show that nano-hydroxyapatite particles can readily be incorporated into photo-crosslinked poly(trimethylene carbonate) networks. Compared to the networks without nano-hydroxyapatite, incorporation of 36.3 wt.% of the apatite resulted in an increase of the E modulus, yield strength and tensile strength from 2.2 MPa to 51 MPa, 0.5 to 1.4 N/mm2 and from 1.3 to 3.9 N/mm2, respectively. We found that composites containing 12.4 wt.% nano-hydroxyapatite had the highest values of strain at break, toughness and average tear propagation strength (376% , 777 N/mm2 and 3.1 N/mm2, respectively).

Graphene Nano-Composites for Hypervelocity Impact Applications

NASA Astrophysics Data System (ADS)

Manasrah, Alharith

The Low Earth Orbit (LEO) is a harsh environment cluttered with natural meteoroids and man-made debris, which can travel at velocities approaching 15 km/s. Most space activities within the LEO will encounter this environment. Thus, the spacecraft and its hardware must be designed to survive debris impact. This research introduces new procedures to produce a nano-composite material with mortar-brick nano-structure inspired from nacre. Nacre-like composites were successfully manufactured, based on three host polymers, with a wide range of graphene concentrations. The manufactured exfoliated graphene nano-platelet, embedded in a host polymer, provided good potential for enhancement of the hypervelocity impact (HVI) shield resistance. The nano-composites are suggested for use as a coating. Moreover, explicit dynamic finite element studies were conducted for further investigation of the hypervelocity impact of the graphene-based coatings in order to understand the effect of the coating on the crater formation and the exit velocity. This dissertation presents the results of the characterization and numerical sensitivity study of the developed material parameters. The numerical simulations were performed by implementing Autodyn smooth particle hydrodynamics. This study provides innovative, low-weight shielding enhancements for spacecraft, as well as other promising applications for the manufactured nano-composites.

Experimental Assessment of the Mass of Ash Residue During the Burning of Droplets of a Composite Liquid Fuel

NASA Astrophysics Data System (ADS)

Glushkov, D. O.; Zakharevich, A. V.; Strizhak, P. A.; Syrodoi, S. V.

2018-03-01

An experimental study has been made of the regularities of burning of single droplets of typical compositions of a composite liquid fuel during the heating by an air flow with a varied temperature (600-900 K). As the basic components of the compositions of the composite liquid fuel, use was made of the: waste of processing (filter cakes) of bituminous coals of ranks K, C, and T, waste motor, turbine, and transformer oils, process mixture of mazut and oil, heavy crude, and plasticizer. The weight fraction of a liquid combustible component (petroleum) product) ranged within 0-15%. Consideration has been given to droplets of a composite liquid fuel with dimensions (radius) of 0.5 to 2 mm. Conditions of low-temperature initiation of combustion to ensure a minimum possible mass of solid incombustible residue have been determined. Petroleum products have been singled out whose addition to the composition of the composite liquid fuel tends to increase the ash mass (compared to the corresponding composition without a liquid combustible component). Approximation dependences have been obtained which permit predicting the influence of the concentration of the liquid petroleum product as part of the composite liquid fuel on the ash-residue mass.

Experimental Assessment of the Mass of Ash Residue During the Burning of Droplets of a Composite Liquid Fuel

NASA Astrophysics Data System (ADS)

Glushkov, D. O.; Zakharevich, A. V.; Strizhak, P. A.; Syrodoi, S. V.

2018-05-01

An experimental study has been made of the regularities of burning of single droplets of typical compositions of a composite liquid fuel during the heating by an air flow with a varied temperature (600-900 K). As the basic components of the compositions of the composite liquid fuel, use was made of the: waste of processing (filter cakes) of bituminous coals of ranks K, C, and T, waste motor, turbine, and transformer oils, process mixture of mazut and oil, heavy crude, and plasticizer. The weight fraction of a liquid combustible component (petroleum) product) ranged within 0-15%. Consideration has been given to droplets of a composite liquid fuel with dimensions (radius) of 0.5 to 2 mm. Conditions of low-temperature initiation of combustion to ensure a minimum possible mass of solid incombustible residue have been determined. Petroleum products have been singled out whose addition to the composition of the composite liquid fuel tends to increase the ash mass (compared to the corresponding composition without a liquid combustible component). Approximation dependences have been obtained which permit predicting the influence of the concentration of the liquid petroleum product as part of the composite liquid fuel on the ash-residue mass.

Effect of gamma radiation and accelerated aging on the mechanical and thermal behavior of HDPE/HA nano-composites for bone tissue regeneration

PubMed Central

2013-01-01

Background The replacement of hard tissues demands biocompatible and sometimes bioactive materials with properties similar to those of bone. Nano-composites made of biocompatible polymers and bioactive inorganic nano particles such as HDPE/HA have attracted attention as permanent bone substitutes due to their excellent mechanical properties and biocompatibility. Method The HDPE/HA nano-composite is prepared using melt blending at different HA loading ratios. For evaluation of the degradation by radiation, gamma rays of 35 kGy, and 70 kGy were used to irradiate the samples at room temperature in vacuum. The effects of accelerated ageing after gamma irradiation on morphological, mechanical and thermal properties of HDPE/HA nano-composites were measured. Results In Vitro test results showed that the HDPE and all HDPE/HA nano-composites do not exhibit any cytotoxicity to WISH cell line. The results also indicated that the tensile properties of HDPE/HA nano-composite increased with increasing the HA content except fracture strain decreased. The dynamic mechanical analysis (DMA) results showed that the storage and loss moduli increased with increasing the HA ratio and the testing frequency. Finally, it is remarked that all properties of HDPE/HA is dependent on the irradiation dose and accelerated aging. Conclusion Based on the experimental results, it is found that the addition of 10%, 20% and 30% HA increases the HDPE stiffness by 23%, 44 and 59% respectively. At the same time, the G’ increased from 2.25E11 MPa for neat HDPE to 4.7E11 MPa when 30% HA was added to the polymer matrix. Also, significant improvements in these properties have been observed due to irradiation. Finally, the overall properties of HDPE and its nano-composite properties significantly decreased due to aging and should be taken into consideration in the design of bone substitutes. It is attributed that the developed HDPE/HA nano-composites could be a good alternative material for bone tissue regeneration due to their acceptable properties. PMID:24059280

Effect of gamma radiation and accelerated aging on the mechanical and thermal behavior of HDPE/HA nano-composites for bone tissue regeneration.

PubMed

Alothman, Othman Y; Almajhdi, Fahad N; Fouad, H

2013-09-24

The replacement of hard tissues demands biocompatible and sometimes bioactive materials with properties similar to those of bone. Nano-composites made of biocompatible polymers and bioactive inorganic nano particles such as HDPE/HA have attracted attention as permanent bone substitutes due to their excellent mechanical properties and biocompatibility. The HDPE/HA nano-composite is prepared using melt blending at different HA loading ratios. For evaluation of the degradation by radiation, gamma rays of 35 kGy, and 70 kGy were used to irradiate the samples at room temperature in vacuum. The effects of accelerated ageing after gamma irradiation on morphological, mechanical and thermal properties of HDPE/HA nano-composites were measured. In Vitro test results showed that the HDPE and all HDPE/HA nano-composites do not exhibit any cytotoxicity to WISH cell line. The results also indicated that the tensile properties of HDPE/HA nano-composite increased with increasing the HA content except fracture strain decreased. The dynamic mechanical analysis (DMA) results showed that the storage and loss moduli increased with increasing the HA ratio and the testing frequency. Finally, it is remarked that all properties of HDPE/HA is dependent on the irradiation dose and accelerated aging. Based on the experimental results, it is found that the addition of 10%, 20% and 30% HA increases the HDPE stiffness by 23%, 44 and 59% respectively. At the same time, the G' increased from 2.25E11 MPa for neat HDPE to 4.7E11 MPa when 30% HA was added to the polymer matrix. Also, significant improvements in these properties have been observed due to irradiation. Finally, the overall properties of HDPE and its nano-composite properties significantly decreased due to aging and should be taken into consideration in the design of bone substitutes. It is attributed that the developed HDPE/HA nano-composites could be a good alternative material for bone tissue regeneration due to their acceptable properties.

The Evolution of Electrospray Generated Droplets is Not Affected by Ionization Mode

NASA Astrophysics Data System (ADS)

Liigand, Piia; Heering (Suu), Agnes; Kaupmees, Karl; Leito, Ivo; Girod, Marion; Antoine, Rodolphe; Kruve, Anneli

2017-10-01

Ionization efficiency and mechanism in ESI is strongly affected by the properties of mobile phase. The use of mobile-phase properties to accurately describe droplets in ESI source is convenient but may be inadequate as the composition of the droplets is changing in the plume due to electrochemical reactions occurring in the needle tip as well as continuous drying and fission of droplets. Presently, there is paucity of research on the effect of the polarity of the ESI mode on mobile phase composition in the droplets. In this paper, the change in the organic solvent content, pH, and droplet size are studied in the ESI plume in both ESI+ and ESI- ionization mode. We introduce a rigorous way - the absolute pH (pHabs H 2 O) - to describe pH change in the plume that takes into account organic solvent content in the mobile phase. pHabs H 2 O enables comparing acidities of ESI droplets with different organic solvent contents. The results are surprisingly similar for both ionization modes, indicating that the dynamics of the change of mobile-phase properties is independent from the ESI mode used. This allows us to conclude that the evolution of ESI droplets first of all proceeds via the evaporation of the organic modifier and to a lesser extent via fission of smaller droplets from parent droplets. Secondly, our study shows that qualitative findings related to the ESI process obtained on the ESI+ mode can almost directly be applied also in the ESI- mode. [Figure not available: see fulltext.

Acoustic Properties of Polyurethane Composition Reinforced with Carbon Nanotubes and Silicon Oxide Nano-powder

NASA Astrophysics Data System (ADS)

Orfali, Wasim A.

This article demonstrates the acoustic properties of added small amount of carbon-nanotube and siliconoxide nano powder (S-type, P-Type) to the host material polyurethane composition. By adding CNT and/or nano-silica in the form of powder at different concentrations up to 2% within the PU composition to improve the sound absorption were investigated in the frequency range up to 1600 Hz. Sound transmission loss measurement of the samples were determined using large impedance tube. The tests showed that addition of 0.2 wt.% Silicon Oxide Nano-powder and 0.35 wt.% carbon nanotube to polyurethane composition improved sound transmissions loss (Sound Absorption) up to 80 dB than that of pure polyurethane foam sample.

Chemically designed Pt/PPy nano-composite for effective LPG gas sensor.

PubMed

Gaikwad, Namrata; Bhanoth, Sreenu; More, Priyesh V; Jain, G H; Khanna, P K

2014-03-07

Simultaneous in situ reduction of hexachloroplatinic acid by the amine group in the pyrrole monomer and oxidation of pyrrole to form polypyrrole (PPy) was examined. The reactions were performed at various temperatures to understand the degree of reduction of platinum precursor as well as doping of polypyrrole with Pt(II) chloro-complex. Spectroscopic images revealed different morphologies for the Pt/PPy nano-composite prepared at various temperatures. The as-prepared Pt/PPy nano-composite samples were tested for their ability to sense liquefied petroleum gas (LPG) which resulted in excellent sensing at relatively low temperature. The porous nature and ohmic contact between the PPy and platinum nanoparticles makes the as-prepared Pt/PPy nano-composite highly useful for sensors as well as electronic applications.

Compositional evolution of particle-phase reaction products and water in the heterogeneous OH oxidation of model aqueous organic aerosols

NASA Astrophysics Data System (ADS)

Chim, Man Mei; Cheng, Chiu Tung; Davies, James F.; Berkemeier, Thomas; Shiraiwa, Manabu; Zuend, Andreas; Nin Chan, Man

2017-12-01

Organic compounds present at or near the surface of aqueous droplets can be efficiently oxidized by gas-phase OH radicals, which alter the molecular distribution of the reaction products within the droplet. A change in aerosol composition affects the hygroscopicity and leads to a concomitant response in the equilibrium amount of particle-phase water. The variation in the aerosol water content affects the aerosol size and physicochemical properties, which in turn governs the oxidation kinetics and chemistry. To attain better knowledge of the compositional evolution of aqueous organic droplets during oxidation, this work investigates the heterogeneous OH-radical-initiated oxidation of aqueous methylsuccinic acid (C5H8O4) droplets, a model compound for small branched dicarboxylic acids found in atmospheric aerosols, at a high relative humidity of 85 % through experimental and modeling approaches. Aerosol mass spectra measured by a soft atmospheric pressure ionization source (Direct Analysis in Real Time, DART) coupled with a high-resolution mass spectrometer reveal two major products: a five carbon atom (C5) hydroxyl functionalization product (C5H8O5) and a C4 fragmentation product (C4H6O3). These two products likely originate from the formation and subsequent reactions (intermolecular hydrogen abstraction and carbon-carbon bond scission) of tertiary alkoxy radicals resulting from the OH abstraction occurring at the methyl-substituted carbon site. Based on the identification of the reaction products, a kinetic model of oxidation (a two-product model) coupled with the Aerosol Inorganic-Organic Mixtures Functional groups Activity Coefficients (AIOMFAC) model is built to simulate the size and compositional changes of aqueous methylsuccinic acid droplets during oxidation. Model results show that at the maximum OH exposure, the droplets become slightly more hygroscopic after oxidation, as the mass fraction of water is predicted to increase from 0.362 to 0.424; however, the diameter of the droplets decreases by 6.1 %. This can be attributed to the formation of volatile fragmentation products that partition to the gas phase, leading to a net loss of organic species and associated particle-phase water, and thus a smaller droplet size. Overall, fragmentation and volatilization processes play a larger role than the functionalization process in determining the evolution of aerosol water content and droplet size at high-oxidation stages.

Manufacture and characterisation of EmDerm-novel hierarchically structured bio-active scaffolds for tissue regeneration.

PubMed

Lim, Xuxin; Potter, Matthew; Cui, Zhanfeng; Dye, Julian F

2018-06-05

There are significant challenges for using emulsion templating as a method of manufacturing macro-porous protein scaffolds. Issues include protein denaturation by adsorption at hydrophobic interfaces, emulsion instability, oil droplet and surfactant removal after protein gelation, and compatible cross-linking methods. We investigated an oil-in-water macro-emulsion stabilised with a surfactant blend, as a template for manufacturing protein-based nano-structured bio-intelligent scaffolds (EmDerm) with tuneable micro-scale porosity for tissue regeneration. Prototype EmDerm scaffolds were made using either collagen, through thermal gelation, fibrin, through enzymatic coagulation or collagen-fibrin composite. Pore size was controlled via surfactant-to-oil phase ratio. Scaffolds were crosslink-stabilised with EDC/NHS for varying durations. Scaffold micro-architecture and porosity were characterised with SEM, and mechanical properties by tensiometry. Hydrolytic and proteolytic degradation profiles were quantified by mass decrease over time. Human dermal fibroblasts, endothelial cells and bone marrow derived mesenchymal stem cells were used to investigate cytotoxicity and cell proliferation within each scaffold. EmDerm scaffolds showed nano-scale based hierarchical structures, with mean pore diameters ranging from 40-100 microns. The Young's modulus range was 1.1-2.9 MPa, and ultimate tensile strength was 4-16 MPa. Degradation rate was related to cross-linking duration. Each EmDerm scaffold supported excellent cell ingress and proliferation compared to the reference materials Integra™ and Matriderm™. Emulsion templating is a novel rapid method of fabricating nano-structured fibrous protein scaffolds with micro-scale pore dimensions. These scaffolds hold promising clinical potential for regeneration of the dermis and other soft tissues, e.g., for burns or chronic wound therapies.

A novel crystallization technique of hydroxyapatite utilizing contact reaction of minute droplet with atmospheric plasmas: Effects of the liquid source composition on the produced crystal properties

NASA Astrophysics Data System (ADS)

Wada, Y.; Kobayashi, T.; Matsumoto, M.; Onoe, K.

2017-10-01

To develop the technique for the control of the crystal composition and properties such as size distribution and morphology utilizing the contact reaction field around the minute droplets in atmospheric pressure plasma, fine spherical particles of hydroxyapatite ((Ca10(PO4)6(OH)2); HAp) were synthesized by a new plasma crystallization method. In this work, to elucidate the effects of the production region and crystal properties of hydroxyapatite for the liquid source composition, Ca2+ concentration and the Ca/P molar ratio in minute droplets were varied. The following results were obtained: (1) fine spherical HAp particles can be produced by the introduction of minute droplets with the initial Ca2+ concentration ((CCa)0) of 0.50 mol/l and the Ca/P molar ratio of 1.67. (2) When the (CCa)0 is set in the range higher than 1.00 mol/l at the constant Ca/P molar ratio of 1.67, fine spherical particles of β-TCP and HAp mixture are crystallized. (3) For the Ca/P molar ratio below 1.67, α-TCP and HAp co-precipitated. (4) The composition of the produced particles depends on both the reactant concentration and Ca/P molar ratio in the HAp source solution. (5) The dependence of the reactant concentration on the average size of the produced HAp particles is large compared with droplet size.

The SPRING Nanoenergetics Hub at UTD

DTIC Science & Technology

2008-12-01

synthesis and processing of advanced nanostructured materials, the structure and property characterization needed for materials optimization, the...nano-particles into hexane solvent a deposited films. Here we are modeling that processes to see how the droplet evaporation progresses in time. What...nanofibers was determined by powder X-ray diffraction (XRD) (Scintag XDS 2000 X-ray diffractometer with Cu Ka radiation). The fiber morphology was

Influences of surface modification of nano-silica by silane coupling agents on the thermal and frictional properties of cyanate ester resin

NASA Astrophysics Data System (ADS)

Chuang, Wang; Geng-sheng, Jiao; Lei, Peng; Bao-lin, Zhu; Ke-zhi, Li; Jun-long, Wang

2018-06-01

The surface of nano-silicon dioxide (nano-SiO2) particles was modified by small molecular coupling agent KH-560 and macromolecular coupling agent SEA-171, respectively, to change the surface activity and structure. The modified nano-SiO2 was then used for reinforcing cyanate ester resin (CE). Influences of the content of nano-SiO2 and the interfacial structure over the thermal and frictional properties of nano-SiO2/CE composites were investigated. The mechanism of the surface modification of silicon dioxide by KH-560 and SEA-171 was discussed. The experimental results show that the addition of coupling agents increased the interfacial bonding between nano-SiO2 particles and the CE resin so that the heat resistance and friction properties of the composites were improved. After surface treatment of nano-SiO2 by SEA-171, the thermal decomposition temperature of the 3.0 wt% nano-SiO2/CE composites increased nearly by 75 °C and the frictional coefficient was reduced by 25% compared with that of the pure CE, and the wear resistance increased by 77%.

Synthesis and Characterization of Nano Boron Nitride Reinforced Magnesium Composites Produced by the Microwave Sintering Method

PubMed Central

Seetharaman, Sankaranarayanan; Subramanian, Jayalakshmi; Tun, Khin Sandar; Hamouda, Abdelmagid S.; Gupta, Manoj

2013-01-01

In this study, magnesium composites with nano-size boron nitride (BN) particulates of varying contents were synthesized using the powder metallurgy (PM) technique incorporating microwave-assisted two-directional sintering followed by hot extrusion. The effect of nano-BN addition on the microstructural and the mechanical behavior of the developed Mg/BN composites were studied in comparison with pure Mg using the structure-property correlation. Microstructural characterization revealed uniform distribution of nano-BN particulates and marginal grain refinement. The coefficient of thermal expansion (CTE) value of the magnesium matrix was improved with the addition of nano-sized BN particulates. The results of XRD studies indicate basal texture weakening with an increase in nano-BN addition. The composites showed improved mechanical properties measured under micro-indentation, tension and compression loading. While the tensile yield strength improvement was marginal, a significant increase in compressive yield strength was observed. This resulted in the reduction of tension-compression yield asymmetry and can be attributed to the weakening of the strong basal texture. PMID:28809252

Screening of lipid composition for scalable fabrication of solvent free lipid microarrays

NASA Astrophysics Data System (ADS)

Ghazanfari, Lida; Lenhert, Steven

2016-12-01

Liquid microdroplet arrays on surfaces are a promising approach to the miniaturization of laboratory processes such as high throughput screening. The fluid nature of these droplets poses unique challenges and opportunities in their fabrication and application, particularly for the scalable integration of multiple materials over large areas and immersion into cell culture solution. Here we use pin spotting and nanointaglio printing to screen a library of lipids and their mixtures for their compatibility with these fabrication processes, as well as stability upon immersion into aqueous solution. More than 200 combinations of natural and synthetic oils composed of fatty acids, triglycerides, and hydrocarbons were tested for their pin-spotting and nanointaglio print quality and their ability to contain the fluorescent compound TRITC upon immersion in water. A combination of castor oil and hexanoic acid at the ratio of 1:1 (w/w) was found optimal for producing reproducible patterns that are stable upon immersion into water. This method is capable of large scale nano-materials integration.

Spray forming process for producing molds, dies and related tooling

DOEpatents

McHugh, Kevin M.; Key, James F.

1998-01-01

A method for spray forming manufacturing of near-net-shape molds, dies and related toolings, wherein liquid material such as molten metal, metallic alloys, or polymers are atomized into fine droplets by a high temperature, high velocity gas and deposited onto a pattern. Quenching of the atomized droplets provides a heat sink, thereby allowing undercooled and partially solidified droplets to be formed in-flight. Composites can be formed by combining the atomized droplets with solid particles such as whiskers or fibers.

Spray forming system for producing molds, dies and related tooling

DOEpatents

McHugh, Kevin M.

2000-01-01

A system for the spray forming manufacturing of near-net-shape molds, dies and related toolings, wherein liquid material such as molten metal, metallic alloys, or polymers are atomized into fine droplets by a high temperature, high velocity gas and deposited onto a pattern. Quenching of the atomized droplets provides a heat sink, thereby allowing undercooled and partially solidified droplets to be formed in-flight. Composites can be formed by combining the atomized droplets with solid particles such as powders, whiskers or fibers.

Spray forming process for producing molds, dies and related tooling

DOEpatents

McHugh, K.M.; Key, J.F.

1998-02-17

A method is disclosed for spray forming manufacturing of near-net-shape molds, dies and related toolings, wherein liquid material such as molten metal, metallic alloys, or polymers are atomized into fine droplets by a high temperature, high velocity gas and deposited onto a pattern. Quenching of the atomized droplets provides a heat sink, thereby allowing undercooled and partially solidified droplets to be formed in-flight. Composites can be formed by combining the atomized droplets with solid particles such as whiskers or fibers. 17 figs.

Fabrication and mechanical evaluation of hydroxyapatite/oxide nano-composite materials.

PubMed

Mohamed, Khaled R; Beherei, Hanan H; El Bassyouni, Gehan T; El Mahallawy, Nahed

2013-10-01

In the current study, the semiconducting metal oxides such as nano-ZnO and SiO2 powders were prepared via sol-gel technique and conducted on nano-hydroxyapatite (nHA) which was synthesized by chemical precipitation. The properties of fabricated nano-structured composites containing different ratios of HA, ZnO and SiO2 were examined using X-ray diffraction (XRD), Fourier transform infrared (FT-IR) spectroscopy, scanning electron microscope (SEM) and transmission electron microscope (TEM) techniques. The effect of the variation of ratios between the three components on mechanical, microstructure and in-vitro properties was assessed to explore the possibility of enhancing these properties. The results proved that the mechanical properties exhibited an increment with increasing the ZnO content at the extent of HA. In-vitro study proved the formation and nucleation of apatite onto the surface of the fabricated composites after one week of immersion. It is concluded that HA composites containing SiO2 or SiO2/ZnO content had a suitable mechanical properties and ability to form apatite particles onto the composite surface. Based on bioactivity behavior, Si-HA is more bioactive than pure hydroxyapatite and nano-arrangements will provide an interface for better bone formation. Therefore, these nano-composites will be promising as bone substitutes especially in load bearing sites. Copyright © 2013 Elsevier B.V. All rights reserved.

The effect of nano-SiC on characteristics of ADC12/nano-SiC composite with Sr and TiB addition produced by stir casting process

NASA Astrophysics Data System (ADS)

Anne Zulfia, S.; Salshabia, Nadella; Dhaneswara, Donanta; Utomo, Budi Wahyu

2018-05-01

ADC12 reinforced nano SiC has been successfully produced by stir casting process. Nano SiC was added into ADC12 alloy varied from 0.05 to 0.3 vf-% while Al-5Ti-1B and Sr were kept constant at 0.04 and 0.02 wt-% respectively to all composites. Mg was added 10 wt% to improve reinforce's wettability. The addition of Al-5Ti-1B to the alloy was as grain refiner while Sr was added to modify Mg2Si. All composites were characterized both microstructures analysis and mechanical properties include tensile strength, hardness, wear rate, impact strength, and porosity. The highest properties of composites was obtained at 0.3 vf-% nano SiC addition with UTS of 155.4 MPa, hardness of 46.16 HRB, impact strength of 0.22 J/mm2, and wear rate of 1.71 × 10-5 mm3/m. Tensile strength and hardness increased as grain size and porosities decreased. The highest wear resistance was investigated on the composition with the highest hardness. Impact strength decreased due to increasing volume fraction of nano-SiC. The phases present in microsturucture was dominantly Mg2Si which also affected mechanical properties of these composites.

Two-year clinical comparison of a flowable-type nano-hybrid composite and a paste-type composite in posterior restoration.

PubMed

Hirata-Tsuchiya, Shizu; Yoshii, Shinji; Ichimaru-Suematsu, Miki; Washio, Ayako; Saito, Noriko; Urata, Mariko; Hanada, Kaori; Morotomi, Takahiko; Kitamura, Chiaki

2017-08-01

The purpose of the present study was to compare the clinical efficacy between a flowable-type nano-hybrid composite and a paste-type composite for posterior restoration. Of 62 posterior teeth in 33 patients (mean age: 34.1 years), 31 were filled with a paste-type composite (Heliomolar [HM] group), and another 31 with a flowable nano-hybrid composite (MI FIL [MI] group). Clinical efficacy was evaluated at 2 years after the restoration. There were no differences for retention, surface texture deterioration, anatomical form change, deterioration of marginal adaptation, and secondary caries, while a statistical difference was found for marginal discoloration, which was significantly greater in the HM group (P < 0.05). Furthermore, color matching in the MI group was superior to that in the HM group immediately after the restoration throughout the study period. The present 2-year clinical evaluation of different composites showed that the flowable nano-hybrid composite could be an effective esthetic material for posterior restoration. © 2016 John Wiley & Sons Australia, Ltd.

Optical, thermal and morphological study of ZnS doped PVA polymer nano composites

NASA Astrophysics Data System (ADS)

Guruswamy, B.; Ravindrachary, V.; Shruthi, C.; Sagar, Rohan N.; Hegde, Shreedatta

2018-05-01

The effect of ZnS nano particle doping on optical, thermal properties and morphological study of the PVA polymer has been investigated using FTIR, UV-Visible and TGA, FESEM techniques. Nano sized ZnS particles were synthesized by a simple wet chemical route. Pure and ZnS/PVA nano composites were prepared using solution casting technique. The FTIR study confirms that the ZnS nano particles interacts with the OH group of PVA polymer and forms the complex. The formation of these complexes affects the optical and thermal properties of the composite. The changes in optical properties were studied using UV-Vis absorption method. The variation in thermal property was analysed using TGA results. The modified surface morphology analysis was carried out using FESEM.

Composition and formation of organic aerosol particles in the Amazon

NASA Astrophysics Data System (ADS)

Pöhlker, C.; Wiedemann, K.; Sinha, B.; Shiraiwa, M.; Gunthe, S. S.; Artaxo, P.; Gilles, M. K.; Kilcoyne, A. L. D.; Moffet, R. C.; Smith, M.; Weigand, M.; Martin, S. T.; Pöschl, U.; Andreae, M. O.

2012-04-01

We applied scanning transmission X-ray microscopy with near edge X-ray absorption fine structure (STXM-NEXAFS) analysis to investigate the morphology and chemical composition of aerosol samples from a pristine tropical environment, the Amazon Basin. The samples were collected in the Amazonian rainforest during the rainy season and can be regarded as a natural background aerosol. The samples were found to be dominated by secondary organic aerosol (SOA) particles in the fine and primary biological aerosol particles (PBAP) in the coarse mode. Lab-generated SOA-samples from isoprene and terpene oxidation as well as pure organic compounds from spray-drying of aqueous solution were measured as reference samples. The aim of this study was to investigate the microphysical and chemical properties of a tropical background aerosol in the submicron size range and its internal mixing state. The lab-generated SOA and pure organic compounds occurred as spherical and mostly homogenous droplet-like particles, whereas the Amazonian SOA particles comprised a mixture of homogeneous droplets and droplets having internal structures due to atmospheric aging. In spite of the similar morphological appearance, the Amazon samples showed considerable differences in elemental and functional group composition. According to their NEXAFS spectra, three chemically distinct types of organic material were found and could be assigned to the following three categories: (1) particles with a pronounced carboxylic acid (COOH) peak similar to those of laboratory-generated SOA particles from terpene oxidation; (2) particles with a strong hydroxy (COH) signal similar to pure carbohydrate particles; and (3) particles with spectra resembling a mixture of the first two classes. In addition to the dominant organic component, the NEXAFS spectra revealed clearly resolved potassium (K) signals for all analyzed particles. During the rainy season and in the absence of anthropogenic influence, active biota is regarded to be the major potassium source. In addition a strong size dependence of the K mass fraction in the SOA particles has been found, with highest K content in small particles. We suggest that K-rich biogenic salts act as a template for condensational growth by low-volatility organic compounds from atmospheric isoprene and terpene oxidation. The presence of K-rich salts in SOA particles has been confirmed by scanning electron microscopy (SEM) and secondary ion mass spectrometry (nanoSIMS) techniques. Seeding of SOA particles by biogenic salts may explain the absence of new particle formation events in pristine boundary layer air over the Amazonian rainforest.

Effect of Temperature on Nucleation of Nanocrystalline Indium Tin Oxide Synthesized by Electron-Beam Evaporation

NASA Astrophysics Data System (ADS)

Shen, Yan; Zhao, Yujun; Shen, Jianxing; Xu, Xiangang

2017-07-01

Indium tin oxide (ITO) has been widely applied as a transparent conductive layer and optical window in light-emitting diodes, solar cells, and touch screens. In this paper, crystalline nano-sized ITO dendrites are obtained using an electron-beam evaporation technique. The surface morphology of the obtained ITO was studied for substrate temperatures of 25°C, 130°C, 180°C, and 300°C. Nano-sized crystalline dendrites were synthesized only at a substrate temperature of 300°C. The dendrites had a cubic structure, confirmed by the results of x-ray diffraction and transmission electron microscopy. The growth mechanism of the nano-crystalline dendrites could be explained by a vapor-liquid-solid (VLS) growth model. The catalysts of the VLS process were indium and tin droplets, confirmed by varying the substrate temperature, which further influenced the nucleation of the ITO dendrites.

Nano-emulsions as vehicles for topical delivery of forskolin.

PubMed

Miastkowska, Małgorzata; Sikora, Elżbieta; Lasoń, Elwira; Garcia-Celma, Maria Jose; Escribano-Ferrer, Elvira; Solans, Conxita; Llinas, Meritxell

2017-01-01

Two O/W forskolin-loaded nano-emulsions (0.075% wt.) based on medium chain triglycerides (MCT) and stabilized by a nonionic surfactant (Polysorbate 80 or Polysorbate 40) were studied as forskolin delivery systems. The nano-emulsions were prepared by the PIC method. The mean droplet size of the nano-emulsions with Polysorbate 80 and Polysorbate 40 with oil/surfactant (O/S) ratios of 20/80 and 80% water concentration, measured by Dynamic Light Scattering (DLS), was of 118 nm and 111 nm, respectively. Stability of the formulations, as assessed by light backscattering for 24 h, showed that both nano-emulsions were stable at 25°C. Studies of forskolin in vitro skin permeation from the nano-emulsions and from a triglyceride solution were carried out at 32°C, using Franz-type diffusion cells. A mixture of PBS/ethanol (60/40 v/v) was used as a receptor solution. The highest flux and permeability coefficient was obtained for the system stabilized with Polysorbate 80 (6.91±0.75 µg · cm -2 ·h -1 and 9.21 · 10 -3 ±1.00 · 10 -3 cm · h -1 , respectively) but no significant differences were observed with the flux and permeability coefficient value of forskolin dissolved in oil. The obtained results showed that the nano-emulsions developed in this study could be used as effective carriers for topical administration of forskolin.

Polymer formulations for gettering hydrogen

DOEpatents

Shepodd, Timothy J.; Even, Jr., William R.

2000-01-01

A novel method for preparing a hydrogenation composition comprising organic polymer molecules having carbon--carbon double bonds, for removing hydrogen from the atmosphere within enclosed spaces and particularly from atmospheres within enclosed spaces that contain air, water vapor, oxygen, carbon dioxide or ammonia. The organic polymers molecules containing carbon--carbon double bonds throughout their structures, preferably polybutadiene, polyisoprene and derivatives thereof, intimately mixed with an insoluble noble metal catalyst composition. High molecular weight polymers may be added to the organic polymer/catalyst mixture in order to improve their high temperature performance. The hydrogenation composition is prepared by dispersing the polymers in a suitable solvent, forming thereby a solution suspension, flash-freezing droplets of the solution in a liquid cryogen, freeze-drying the frozen droplets to remove frozen solvent incorporated in the droplets, and recovering the dried powder thus formed.

Study on the repeatability of manufacturing nano-silica (SiO2) reinforced composite laminates

NASA Astrophysics Data System (ADS)

Prince Jeya Lal, L.; Ramesh, S.; Natarajan, Elango

2018-04-01

Repeatability to manufacture nano-silica reinforced composite laminates with consistent mechanical properties is studied. In this study, composite laminates are manufactured by hand layup and there after mechanical properties of the laminates are evaluated under tensile and flexural loading conditions. Composite laminates are fabricated and tested under equivalent conditions. Plain weave E-Glass fabric and epoxy LY556 are used as reinforcement and matrix. Nano-silica of size 17nm is used as filler. To enhance the reliability of composite characterization, utmost care is taken to avoid defects like voids, surface defects and under-saturations. Homogeneous distribution of nano silica in matrix is analyzed using TEM study. Inconsistencies in mechanical properties are quantified by coefficient of variation. In this study, the coefficient of variation is estimated in terms of break load for tensile test is 4.45 and for flexural test is 2.27 and is well within the limits.

Focusing experiments in plasma coaxial railguns

NASA Astrophysics Data System (ADS)

Driga, M. D.; Cook, R. W.; Thelen, R. F.

1986-11-01

Results are reported from experiments on focusing of plasma fired from a coaxial electromagnetic gun (CEMG). The plasma used, obtained by exploding a metallic fuse at the gun breech, comprised metal vapor, metallic liquid droplets and small chunks of solid metal. An azimuthal current, and thereby an axial field, was introduced at the breech of the CEMG by a solenoid. Previous studies indicated that the field would cause vaporized metal to form into a self-stabilizing toroidal plasma. Test shots instrumented with Languir probes and pick-up coils did not reveal the presence of toroidal plasma rings. However, post-mortem of the 30 cm rail showed that only one-third of the 3 mg Al fuse metal remained in the bore. Further, a toroidal hole was punched in a diagnostic screen at the bore exit after one shot.

Data reduction and analysis of graphite fiber release experiments

NASA Technical Reports Server (NTRS)

Lieberman, P.; Chovit, A. R.; Sussholz, B.; Korman, H. F.

1979-01-01

The burn and burn/explode effects on aircraft structures were examined in a series of fifteen outdoor tests conducted to verify the results obtained in previous burn and explode tests of carbon/graphite composite samples conducted in a closed chamber, and to simulate aircraft accident scenarios in which carbon/graphite fibers would be released. The primary effects that were to be investigaged in these tests were the amount and size distribution of the conductive fibers released from the composite structures, and how these various sizes of fibers transported downwind. The structures included plates, barrels, aircraft spoilers and a cockpit. The heat sources included a propane gas burner and 20 ft by 20 ft and 40 ft by 60 ft JP-5 pool fires. The larger pool fire was selected to simulate an aircraft accident incident. The passive instrumentation included sticky paper and sticky bridal veil over an area 6000 ft downwind and 3000 ft crosswind. The active instrumentation included instrumented meteorological towers, movies, infrared imaging cameras, LADAR, high voltage ball gages, light emitting diode gages, microwave gages and flame velocimeter.

3D Modeling of Transport Phenomena and the Injection of the Solution Droplets in the Solution Precursor Plasma Spraying

NASA Astrophysics Data System (ADS)

Shan, Yanguang; Coyle, Thomas W.; Mostaghimi, Javad

2007-12-01

Solution precursor plasma spraying has been used to produce finely structured ceramic coatings with nano- and sub-micrometric features. This process involves the injection of a solution spray of ceramic salts into a DC plasma jet under atmospheric condition. During the process, the solvent vaporizes as the droplet travel downstream. Solid particles are finally formed due to the precipitation of the solute, and the particle are heated up and accelerated to the substrate to generate the coating. This article describes a 3D model to simulate the transport phenomena and the trajectory and heating of the solution spray in the process. The jet-spray two-way interactions are considered. A simplified model is employed to simulate the evolution process and the formation of the solid particle from the solution droplet in the plasma jet. The temperature and velocity fields of the jet are obtained and validated. The particle size, velocity, temperature, and position distribution on the substrate are predicted.

Structure Shift of GaN Among Nanowall Network, Nanocolumn, and Compact Film Grown on Si (111) by MBE.

PubMed

Zhong, Aihua; Fan, Ping; Zhong, Yuanting; Zhang, Dongping; Li, Fu; Luo, Jingting; Xie, Yizhu; Hane, Kazuhiro

2018-02-13

Structure shift of GaN nanowall network, nanocolumn, and compact film were successfully obtained on Si (111) by plasma-assisted molecular beam epitaxy (MBE). As is expected, growth of the GaN nanocolumns was observed in N-rich condition on bare Si, and the growth shifted to compact film when the Ga flux was improved. Interestingly, if an aluminum (Al) pre-deposition for 40 s was carried out prior to the GaN growth, GaN grows in the form of the nanowall network. Results show that the pre-deposited Al exits in the form of droplets with typical diameter and height of ~ 80 and ~ 6.7 nm, respectively. A growth model for the nanowall network is proposed and the growth mechanism is discussed. GaN grows in the area without Al droplets while the growth above Al droplets is hindered, resulting in the formation of continuous GaN nanowall network that removes the obstacles of nano-device fabrication.

Structure Shift of GaN Among Nanowall Network, Nanocolumn, and Compact Film Grown on Si (111) by MBE

NASA Astrophysics Data System (ADS)

Zhong, Aihua; Fan, Ping; Zhong, Yuanting; Zhang, Dongping; Li, Fu; Luo, Jingting; Xie, Yizhu; Hane, Kazuhiro

2018-02-01

Structure shift of GaN nanowall network, nanocolumn, and compact film were successfully obtained on Si (111) by plasma-assisted molecular beam epitaxy (MBE). As is expected, growth of the GaN nanocolumns was observed in N-rich condition on bare Si, and the growth shifted to compact film when the Ga flux was improved. Interestingly, if an aluminum (Al) pre-deposition for 40 s was carried out prior to the GaN growth, GaN grows in the form of the nanowall network. Results show that the pre-deposited Al exits in the form of droplets with typical diameter and height of 80 and 6.7 nm, respectively. A growth model for the nanowall network is proposed and the growth mechanism is discussed. GaN grows in the area without Al droplets while the growth above Al droplets is hindered, resulting in the formation of continuous GaN nanowall network that removes the obstacles of nano-device fabrication.

Harvesting electrostatic energy using super-hydrophobic surfaces

NASA Astrophysics Data System (ADS)

Pociecha, Dominik; Zylka, Pawel

2016-11-01

Almost all environments are now being extensively populated by miniaturized, nano-powered electronic sensor devices communicated together through wireless sensor networks building Internet of Things (IoT). Various energy harvesting techniques are being more and more frequently proposed for battery-less powering of such remote, unattended, implantable or wearable sensors or other low-power electronic gadgets. Energy harvesting relays on extracting energy from the ambient sources readily accessible at the sensor location and converting it into electrical power. The paper exploits possibility of generating electric energy safely accessible for nano-power electronics using tribo-electric and electrostatic induction phenomena displayed at super-hydrophobic surfaces impinged by water droplets. Mechanism of such interaction is discussed and illustrated by experimental results.

A nano lamella NbTi–NiTi composite with high strength

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

Jiang, Jiang; Jiang, Daqiang; Hao, Shijie

A hypereutectic Nb60Ti24Ni16 (at%) alloy was prepared by vacuum induction melting, and a nano lamellae NbTi-NiTi composite was obtained by hot-forging and wire-drawing of the ingot Microscopic analysis showed that NbTi and NiTi nano lamellae distributed alternatively in the composite, and aligned along the wire axial direction, with a high volume fraction (similar to 70%) of NbTi nano lamellae. In situ synchrotron X-ray diffraction analysis revealed that stress induced martensitic transformation occurred upon loading, which would effectively weaken the stress concentration at the interface and avoid the introduction of defects into the nano reinforced phase. Then the embedded NbTi nanomore » lamellae exhibited a high elastic strain up to 2.72%, 1.5 times as high as that of the Nb nanowires embedded in a conventional plastic matrix, and the corresponding stress carried by NbTi was evaluated as 2.53 GPa. The high volume fraction of NbTi nano lamellae improved the translation of high strength from the nano reinforced phase into bulk properties of the composite, with a platform stress of similar to 1.7 GPa and a fracture strength of similar to 1.9 GPa. (C) 2015 Elsevier B.V. All rights reserved.« less

ABC Triblock Copolymer Worms: Synthesis, Characterization, and Evaluation as Pickering Emulsifiers for Millimeter-Sized Droplets

PubMed Central

2016-01-01

Polymerization-induced self-assembly (PISA) is used to prepare linear poly(glycerol monomethacrylate)–poly(2-hydroxypropyl methacrylate)–poly(benzyl methacrylate) [PGMA–PHPMA–PBzMA] triblock copolymer nano-objects in the form of a concentrated aqueous dispersion via a three-step synthesis based on reversible addition–fragmentation chain transfer (RAFT) polymerization. First, GMA is polymerized via RAFT solution polymerization in ethanol, then HPMA is polymerized via RAFT aqueous solution polymerization, and finally BzMA is polymerized via “seeded” RAFT aqueous emulsion polymerization. For certain block compositions, highly anisotropic worm-like particles are obtained, which are characterized by small-angle X-ray scattering (SAXS) and transmission electron microscopy (TEM). The design rules for accessing higher order morphologies (i.e., worms or vesicles) are briefly explored. Surprisingly, vesicular morphologies cannot be accessed by targeting longer PBzMA blocks—instead, only spherical nanoparticles are formed. SAXS is used to rationalize these counterintuitive observations, which are best explained by considering subtle changes in the relative enthalpic incompatibilities between the three blocks during the growth of the PBzMA block. Finally, the PGMA–PHPMA–PBzMA worms are evaluated as Pickering emulsifiers for the stabilization of oil-in-water emulsions. Millimeter-sized oil droplets can be obtained using low-shear homogenization (hand-shaking) in the presence of 20 vol % n-dodecane. In contrast, control experiments performed using PGMA–PHPMA diblock copolymer worms indicate that these more delicate nanostructures do not survive even these mild conditions. PMID:27795581

Evaluating Weathering of Food Packaging Polyethylene-Nano-clay Composites: Release of Nanoparticles and their Impacts.

PubMed

Han, Changseok; Zhao, Amy; Varughese, Eunice; Sahle-Demessie, E

2018-01-01

Nano-fillers are increasingly incorporated into polymeric materials to improve the mechanical, barrier or other matrix properties of nanocomposites used for consumer and industrial applications. However, over the life cycle, these nanocomposites could degrade due to exposure to environmental conditions, resulting in the release of embedded nanomaterials from the polymer matrix into the environment. This paper presents a rigorous study on the degradation and the release of nanomaterials from food packaging composites. Films of nano-clay-loaded low-density polyethylene (LDPE) composite for food packaging applications were prepared with the spherilene technology and exposed to accelerated weathering of ultraviolet (UV) irradiation or low concentration of ozone at 40 °C. The changes in the structural, surface morphology, chemical and physical properties of the films during accelerated weathering were investigated. Qualitative and quantitative changes in properties of pristine and aged materials and the release of nano-clay proceeded slowly until 130 hr irradiation and then accelerated afterward resulting complete degradation. Although nano-clay increased the stability of LDPE and improved thermal and barrier properties, they accelerated the UV oxidation of LDPE. With increasing exposure to UV, the surface roughness, chemiluminescence index, and carbonyl index of the samples increased while decreasing the intensity of the wide-angle X-ray diffraction pattern. Nano-clay particles with sizes ranging from 2-8 nm were released from UV and ozone weathered composite. The concentrations of released nanoparticles increased with an increase in aging time. Various toxicity tests, including reactive oxygen species generation and cell activity/viability were also performed on the released nano-clay and clay polymer. The released nano-clays basically did not show toxicity. Our combined results demonstrated the degradation properties of nano-clay particle-embedded LDPE composites toxicity of released nano-clay particles to A594 adenocarcinomic human alveolar basal epithelial cells was observed, which will help with future risk based-formulations of exposure.

Exploding conducting film laser pumping apparatus

DOEpatents

Ware, Kenneth D.; Jones, Claude R.

1986-01-01

Exploding conducting film laser optical pumping apparatus. The 342-nm molecular iodine and the 1.315-.mu.m atomic iodine lasers have been optically pumped by intense light from exploding-metal-film discharges. Brightness temperatures for the exploding-film discharges were approximately 25,000 K. Although lower output energies were achieved for such discharges when compared to exploding-wire techniques, the larger surface area and smaller inductance inherent in the exploding-film should lead to improved efficiency for optically-pumped gas lasers.

Interfacial complexation in microfluidic droplets for single-step fabrication of microcapsule

NASA Astrophysics Data System (ADS)

Kaufman, Gilad; Nejati, Siamak; Sarfati, Raphael; Boltyanskiy, Rostislav; Williams, Danielle; Liu, Wei; Schloss, Ashley; Regan, Lynn; Yan, Elsa; Dufrense, Eric; Loewenberg, Michael; Osuji, Chinedum

We present microfluidic interfacial complexation in emulsion droplets as a simple single-step approach for fabricating a large variety of stable monodisperse microcapsules with tailored mechanical properties, protein binding and controlled release behavior. We rely on electrostatic interactions and hydrogen bonding to direct the assembly of complementary species at oil-water droplet interfaces to form microcapsules with polyelectrolyte shells, composite polyelectrolyte-nanoparticle shells, and copolymer-nanofiber shells. Additionally, we demonstrate the formation of microcapsules by adsorption of an amphiphilic bacterial hydrophobin, BslA, at oil-in-water and water-in-oil droplets, and protein capture on these capsules using engineered variants of the hydrophobin. We discuss the composition dependence of mechanical properties, shell thickness and release behavior, and regimes of stability for microcapsule fabrication. Nanoparticle based microcapsules display an intriguing plastic deformation response which enables the formation of large aspect ratio asperities by pipette aspiration of the shell.

Chemical reactions studied at ultra-low temperature in liquid helium clusters

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

Huisken, Friedrich; Krasnokutski, Serge A.

Low-temperature reaction rates are important ingredients for astrophysical reaction networks modeling the formation of interstellar matter in molecular clouds. Unfortunately, such data is difficult to obtain by experimental means. In an attempt to study low-temperature reactions of astrophysical interest, we have investigated relevant reactions at ultralow temperature in liquid helium droplets. Being prepared by supersonic expansion of helium gas at high pressure through a nozzle into a vacuum, large helium clusters in the form of liquid droplets constitute nano-sized reaction vessels for the study of chemical reactions at ultra-low temperature. If the normal isotope {sup 4}He is used, the heliummore » droplets are superfluid and characterized by a constant temperature of 0.37 K. Here we present results obtained for Mg, Al, and Si reacting with O{sub 2}. Mass spectrometry was employed to characterize the reaction products. As it may be difficult to distinguish between reactions occurring in the helium droplets before they are ionized and ion-molecule reactions taking place after the ionization, additional techniques were applied to ensure that the reactions actually occurred in the helium droplets. This information was provided by measuring the chemiluminescence light emitted by the products, the evaporation of helium atoms by the release of the reaction heat, or by laser-spectroscopic identification of the reactants and products.« less

Intercalation of acrylic acid and sodium acrylate into kaolinite and their in situ polymerization

NASA Astrophysics Data System (ADS)

Zhang, Bo; Li, Yanfeng; Pan, Xiaobing; Jia, Xin; Wang, Xiaolong

2007-02-01

Novel nano-composites of poly (acrylic acid)-kaolinite were prepared, and intercalation and in situ polymerization were used in this process. The nano-composites were obtained by in situ polymerization of acrylic acid (AA) and sodium acrylate (AANa) intercalated into organo-kaolinite, which was obtained by refining and chemically modifying with solution intercalation step in order to increase the basal plane distance of the original clay. The modification was completed by using dimethyl-sulfoxide (DMSO)/methanol and potassium acetate (KAc)/water systems step by step. The materials were characterized with the help of XRD, FT-IR and TEM; the results confirmed that poly(acrylic acid) (PAA) and poly(sodium acrylate) (PAANa) were intercalated into the interlamellar spaces of kaolinite, the resulting copolymer composites (CC0 : copolymer crude kaolinite composite, CC1 : copolymer DMSO kaolinite composite, CC2 : copolymer KAc kaolinite composite) of CC2 exhibited a lamellar nano-composite with a mixed nano-morphology, and partial exfoliation of the intercalating clay platelets should be the main morphology. Finally, the effect of neutralization degree on the intercalation behavior was also investigated.

Investigation of mechanical properties of hemp/glass fiber reinforced nano clay hybrid composites

NASA Astrophysics Data System (ADS)

Unki, Hanamantappa Ningappa; Shivanand, H. K.; Vidyasagar, H. N.

2018-04-01

Over the last twenty to thirty years composite materials have been used in engineering field. Composite materials possess high strength, high strength to weight ratio due to these facts composite materials are becoming popular among researchers and scientists. The major proportion of engineering materials consists of composite materials. Composite materials are used in vast applications ranging from day-to-day household articles to highly sophisticated applications. In this paper an attempt is made to prepare three different composite materials using e-glass and Hemp. In this present investigation hybrid composite of Hemp, Glass fiber and Nano clay will be prepared by Hand-layup technique. The glass fiber used in this present investigation is E-glass fiber bi-directional: 90˚ orientation. The composite samples will be made in the form of a Laminates. The wt% of nanoclay added in the preparation of sample is 20 gm constant. The fabricated composite Laminate will be cut into corresponding profiles as per ASTM standards for Mechanical Testing. The effect of addition of Nano clay and variation of Hemp/glass fibers will be studied. In the present work, a new Hybrid composite is developed in which Hemp, E glass fibers is reinforced with epoxy resin and with Nano clay.

Study of nano mechanical properties polydimethylsiloxane (PDMS)/MWCNT composites

NASA Astrophysics Data System (ADS)

Murudkar, Vrishali; Gaonkar, Amita; Deshpande, V. D.; Mhaske, S. T.

2018-05-01

Polydimethylsiloxane (PDMS), a clear elastomer, is a common material used in many applications; but has poor mechanical properties. Carbon nano tubes (CNT) exhibit excellent mechanical properties & hence are used as filler in PDMS. It was found that the elastic modulus and strength of the PDMS/MWCNT nano composites were enhanced by adding MWCNT [1]. Through the nano indentation experiment, the hardness (H), the elastic modulus (E), and other mechanical properties can be determined from very small volumes of materials [2]; hence nano indentation is widely used to study mechanical properties. PDMS/MWCNT composites have enhanced mechanical properties over neat PDMS. FTIR analysis shows bonding between MWCNT and PDMS; which affects the mechanical properties. From AFM study it shows decreasing roughness for increasing MWCNT concentration. Surface morphology (SEM) study shows well dispersion of MWCNT into PDMS matrix.

The influence of the surface composition of mixed monolayer films on the evaporation coefficient of water.

PubMed

Miles, Rachael E H; Davies, James F; Reid, Jonathan P

2016-07-20

We explore the dependence of the evaporation coefficient of water from aqueous droplets on the composition of a surface film, considering in particular the influence of monolayer mixed component films on the evaporative mass flux. Measurements with binary component films formed from long chain alcohols, specifically tridecanol (C13H27OH) and pentadecanol (C15H31OH), and tetradecanol (C14H29OH) and hexadecanol (C16H33OH), show that the evaporation coefficient is dependent on the mole fractions of the two components forming the monolayer film. Immediately at the point of film formation and commensurate reduction in droplet evaporation rate, the evaporation coefficient is equal to a mole fraction weighted average of the evaporation coefficients through the equivalent single component films. As a droplet continues to diminish in surface area with continued loss of water, the more-soluble, shorter alkyl chain component preferentially partitions into the droplet bulk with the evaporation coefficient tending towards that through a single component film formed simply from the less-soluble, longer chain alcohol. We also show that the addition of a long chain alcohol to an aqueous-sucrose droplet can facilitate control over the degree of dehydration achieved during evaporation. After undergoing rapid gas-phase diffusion limited water evaporation, binary aqueous-sucrose droplets show a continued slow evaporative flux that is limited by slow diffusional mass transport within the particle bulk due to the rapidly increasing particle viscosity and strong concentration gradients that are established. The addition of a long chain alcohol to the droplet is shown to slow the initial rate of water loss, leading to a droplet composition that remains more homogeneous for a longer period of time. When the sucrose concentration has achieved a sufficiently high value, and the diffusion constant of water has decreased accordingly so that bulk phase diffusion arrest occurs in the monolayer coated particle, the droplet is found to have lost a greater proportion of its initial water content. A greater degree of slowing in the evaporative flux can be achieved by increasing the chain length of the surface active alcohol, leading to a greater degree of dehydration.

Geometries in Soft Matter From Geometric Frustration, Liquid Droplets to Electrostatics in Solution

NASA Astrophysics Data System (ADS)

Yao, Zhenwei

This thesis explores geometric aspects of soft matter systems. The topics covered fall into three categories: (i) geometric frustrations, including the interplay of geometry and topological defects in two dimensional systems, and the frustration of a planar sheet attached to a curved surface; (ii) geometries of liquid droplets, including the curvature driven instabilities of toroidal liquid droplets and the self-propulsion of droplets on a spatially varying surface topography; (iii) the study of the electric double layer structure around charged spherical interfaces by a geometric method. In (i), we study the crystalline order on capillary bridges with varying Gaussian curvature. Energy requires the appearance of topological defects on the surface, which are natural spots for biological activity and chemical functionalization. We further study how liquid crystalline order deforms flexible structured vesicles. In particular we find faceted tetrahedral vesicle as the ground state, which may lead to the design of supra-molecular structures with tetrahedral symmetry and new classes of nano-carriers. Furthermore, by a simple paper model we explore the geometric frustration on a planar sheet when brought to a negative curvature surface in a designed elasto-capillary system. In (ii), motivated by the idea of realizing crystalline order on a stable toroidal droplet and a beautiful experiment on toroidal droplets, we study the Rayleigh instability and the shrinking instability of thin and fat toroidal droplets, where the toroidal geometry plays an essential role. In (iii), by a geometric mapping we construct an approximate analytic spherical solution to the nonlinear Poisson-Boltzmann equation, and identify the applicability regime of the solution. The derived geometric solution enables further analytical study of spherical electrostatic systems such as colloidal suspensions.

A coating of silane modified silica nanoparticles on PET substrate film for inkjet printing

NASA Astrophysics Data System (ADS)

Wu, J.; Liu, L.; Jiang, B.; Hu, Z.; Wang, X. Q.; Huang, Y. D.; Lin, D. R.; Zhang, Q. H.

2012-04-01

The paper aims to design nanoporous coatings for inkjet printing and study its microstructure influence on the ink absorption. In the present work, two inkjet materials were prepared: one with unmodified nano-SiO2 (S_1), the other with silica coupling agent modified nano-SiO2 (S_2). The surface characteristic changing after modification was investigated by scanning electron microscopy (SEM), atomic force microscopy (AFM). Wetting with contact angles was determined by the dynamic contact angle analysis test (DCAT). Through measurements, the dispersion of modified nano-SiO2 particles in the coating was superior to the dispersion of unmodified nano-SiO2 particles, surface roughness value (Ra) of S_1 was significantly higher than that of S_2, dynamic contact angle of S_2 is smaller than that of S_1 and ink droplet absorption in S_2 was much faster than in S_1. These results also reveal that the modification method is effective and offers a potential way to fabricate inkjet material with the advantages of microstructure and ink absorption over traditional methods.

Multicomponent Droplet Evaporation on Chemical Micro-Patterned Surfaces

PubMed Central

He, Minghao; Liao, Dong; Qiu, Huihe

2017-01-01

The evaporation and dynamics of a multicomponent droplet on a heated chemical patterned surface were presented. Comparing to the evaporation process of a multicomponent droplet on a homogenous surface, it is found that the chemical patterned surface can not only enhance evaporation by elongating the contact line, but also change the evaporation process from three regimes for the homogenous surface including constant contact line (CCL) regime, constant contact angle (CCA) regime and mix mode (MM) to two regimes, i.e. constant contact line (CCL) and moving contact line (MCL) regimes. The mechanism of contact line stepwise movement in MCL regimes in the microscopic range is investigated in detail. In addition, an improved local force model on the contact line was employed for analyzing the critical receding contact angles on homogenous and patterned surfaces. The analysis results agree well for both surfaces, and confirm that the transition from CCL to MCL regimes indicated droplet composition changes from multicomponent to monocomponent, providing an important metric to predict and control the dynamic behavior and composition of a multicomponent droplet using a patterned surface. PMID:28157229

Mechanical Properties of Polymer Nano-composites

NASA Astrophysics Data System (ADS)

Srivastava, Iti

Thermoset polymer composites are increasingly important in high-performance engineering industries due to their light-weight and high specific strength, finding cutting-edge applications such as aircraft fuselage material and automobile parts. Epoxy is the most widely employed thermoset polymer, but is brittle due to extensive cross-linking and notch sensitivity, necessitating mechanical property studies especially fracture toughness and fatigue resistance, to ameliorate the low crack resistance. Towards this end, various nano and micro fillers have been used with epoxy to form composite materials. Particularly for nano-fillers, the 1-100 nm scale dimensions lead to fascinating mechanical properties, oftentimes proving superior to the epoxy matrix. The chemical nature, topology, mechanical properties and geometry of the nano-fillers have a profound influence on nano-composite behavior and hence are studied in the context of enhancing properties and understanding reinforcement mechanisms in polymer matrix nano-composites. Using carbon nanotubes (CNTs) as polymer filler, uniquely results in both increased stiffness as well as toughness, leading to extensive research on their applications. Though CNTs-polymer nano-composites offer better mechanical properties, at high stress amplitude their fatigue resistance is lost. In this work covalent functionalization of CNTs has been found to have a profound impact on mechanical properties of the CNT-epoxy nano-composite. Amine treated CNTs were found to give rise to effective fatigue resistance throughout the whole range of stress intensity factor, in addition to significantly enhancing fracture toughness, ductility, Young's modulus and average hardness of the nano-composite by factors of 57%, 60%, 30% and 45% respectively over the matrix as a result of diminished localized cross-linking. Graphene, a one-atom-thick sheet of atoms is a carbon allotrope, which has garnered significant attention of the scientific community and is predicted to out-perform nanotubes. In the last few years, work has been done by researchers to study bulk mechanical properties of graphene platelets in polymer matrix. This thesis reports the extensive improvements observed in fatigue resistance and fracture toughness of epoxy using graphene platelet as a filler in very small quantities. Though significant property improvements like 75% increase in fracture toughness and 25-fold increase in fatigue resistance were observed for graphene epoxy nano-composites, the toughening mechanisms could not be delineated without thermo-mechanical and micro-mechanical tests. In this work, the bulk mechanical properties of graphene platelet-polymer nano-composites are studied and presented and the toughness mechanisms are identified by fractography, differential scanning calorimetry, and Raman spectroscopy; and then compared to predictions by theoretical models. Strong adherence to the matrix was found to be the key mechanism responsible for the effective reinforcement provided by graphene to the polymer. The strong graphene platelet-matrix interface also leads to extensive crack deflection, which was observed to be the major toughening mechanism in the nano-composite. In this thesis, the bulk mechanical property results are complemented by in-depth characterization of filler-polymer interfacial interactions and interphase formation using a battery of techniques including Raman spectroscopy and atomic force microscopy. Theoretical and empirical models proposed by Faber & Evans and Pezzotti were critically studied and applied. Pezzotti's model was found to corroborate well with experimental results and provided insight into enhancement mechanisms and explains the mechanisms underpinning the toughness loss at high graphene platelet weight fraction. The thesis provides conclusive evidences for the superiority of graphene as a filler for reinforcing polymer matrices. In conclusion, the thesis presents a thorough investigation of one- and two-dimensional carbon nanomaterials as fillers for high-performance polymer nano-composites. The extensive studies performed on graphene provide a strong foundation for graphene as a potential candidate for reinforcing polymers. The superior performance of graphene as a filler is attributed to graphene's high specific surface area, two-dimensional sheet geometry, strong filler-matrix adhesion and the outstanding mechanical properties of the sp2 carbon-bonding network in graphene. The improved mechanical properties of the graphene-polymer nano-composites, concurrent with the cost-effective production are both vital requirements of the industry in adoption of high strength-to-weight ratio polymer composites for various structural applications.

Electrophoretic manipulation of multiple-emulsion droplets

NASA Astrophysics Data System (ADS)

Schoeler, Andreas M.; Josephides, Dimitris N.; Chaurasia, Ankur S.; Sajjadi, Shahriar; Mesquida, Patrick

2014-02-01

Electrophoretic manipulation of multiple-emulsion oil-in-water-in-oil (O/W)/O and water-in-oil-in-water-in-oil (W/O/W)/O core-shell droplets is shown. It was found that the electrophoretic mobility of the droplets is determined solely by the outer water shell, regardless of size or composition of the inner droplets. It was observed that the surface charge of the outer water shell can be changed and the polarity can be reversed through contact with a biased electrode in a similar way as with simple W/O droplets. Furthermore, addition of the anionic surfactant, sodium dodecyl sulfate to the outer water shell reverses the initial polarity and hence, electrophoretic mobility of the core-shell droplets before contact with an electrode. The results have practical implications for the manipulation of oil droplets in a continuous oil phase.

Synthesis and characterization of Au-MWCNT/PEDOT: PSS composite film for optoelectronic applications

NASA Astrophysics Data System (ADS)

Jasna, M.; Anjana, R.; Jayaraj, M. K.

2017-08-01

Recently, flexible organic optoelectronics have got great attention because of their light weight, mechanical flexibility and cost effective fabrication process. Conjugated polymers like PEDOT: PSS are widely used for the transparent electrode applications due to its chemical stability, high conductivity, flexibility and optical transparency in the visible region. Conductivity of the PEDOT: PSS polymer can be enhanced by adding organic solvents or conducting nano fillers like CNT, graphene, etc. Carbon nanotubes are good nano fillers to enhance the conductivity and mechanical strength of PEDOT: PSS composite film. Inthe present work, the effect of gold nano particles in PEDOT: PSS/CNT composite is studied. The conductivity enhancement in PEDOT: PSS/CNT thin films can be attributed to the formation of CNT network in the polymer matrix and conformational change of the PEDOT from benzoid to quinoid structure. Even though the conductivity was enhanced, the transparency of the composite thin films decreased with increase in CNT concentration. To overcome this problem, gold nano particles were attached to CNT walls via chemical route. AuMWCNT/PEDOT: PSS composite films were prepared by spin coating method. TEM images confirmed the decoration of gold nano particles on CNT walls. Electrical and optical properties of the composite films were studied. This simple solution processed conducting films are suitable for optoelectronic applications

Rapid solidification processing system for producing molds, dies and related tooling

DOEpatents

McHugh, Kevin M.

2004-06-08

A system for the spray forming manufacturing of near-net-shape molds, dies and related toolings, wherein liquid material such as molten metal, metallic alloys, or polymers are atomized into fine droplets by a high temperature, high velocity gas and deposited onto a pattern. Quenching of the in-flight atomized droplets provides a heat sink, thereby allowing undercooled and partially solidified droplets to be formed in-flight. Composites can be formed by combining the atomized droplets with solid particles such as powders, whiskers or fibers.

Compositional evolution of particle-phase reaction products and water in the heterogeneous OH oxidation of model aqueous organic aerosols

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

Chim, Man Mei; Cheng, Chiu Tung; Davies, James F.

Organic compounds present at or near the surface of aqueous droplets can be efficiently oxidized by gas-phase OH radicals, which alter the molecular distribution of the reaction products within the droplet. A change in aerosol composition affects the hygroscopicity and leads to a concomitant response in the equilibrium amount of particle-phase water. The variation in the aerosol water content affects the aerosol size and physicochemical properties, which in turn governs the oxidation kinetics and chemistry. To attain better knowledge of the compositional evolution of aqueous organic droplets during oxidation, this work investigates the heterogeneous OH-radical-initiated oxidation of aqueous methylsuccinic acid (C 5Hmore » 8O 4) droplets, a model compound for small branched dicarboxylic acids found in atmospheric aerosols, at a high relative humidity of 85 % through experimental and modeling approaches. Aerosol mass spectra measured by a soft atmospheric pressure ionization source (Direct Analysis in Real Time, DART) coupled with a high-resolution mass spectrometer reveal two major products: a five carbon atom (C 5) hydroxyl functionalization product (C 5H 8O 5) and a C 4 fragmentation product (C 4H 6O 3). These two products likely originate from the formation and subsequent reactions (intermolecular hydrogen abstraction and carbon–carbon bond scission) of tertiary alkoxy radicals resulting from the OH abstraction occurring at the methyl-substituted carbon site. Based on the identification of the reaction products, a kinetic model of oxidation (a two-product model) coupled with the Aerosol Inorganic–Organic Mixtures Functional groups Activity Coefficients (AIOMFAC) model is built to simulate the size and compositional changes of aqueous methylsuccinic acid droplets during oxidation. Model results show that at the maximum OH exposure, the droplets become slightly more hygroscopic after oxidation, as the mass fraction of water is predicted to increase from 0.362 to 0.424; however, the diameter of the droplets decreases by 6.1 %. This can be attributed to the formation of volatile fragmentation products that partition to the gas phase, leading to a net loss of organic species and associated particle-phase water, and thus a smaller droplet size. Overall, fragmentation and volatilization processes play a larger role than the functionalization process in determining the evolution of aerosol water content and droplet size at high-oxidation stages.« less

Compositional evolution of particle-phase reaction products and water in the heterogeneous OH oxidation of model aqueous organic aerosols

DOE PAGES

Chim, Man Mei; Cheng, Chiu Tung; Davies, James F.; ...

2017-12-05

Organic compounds present at or near the surface of aqueous droplets can be efficiently oxidized by gas-phase OH radicals, which alter the molecular distribution of the reaction products within the droplet. A change in aerosol composition affects the hygroscopicity and leads to a concomitant response in the equilibrium amount of particle-phase water. The variation in the aerosol water content affects the aerosol size and physicochemical properties, which in turn governs the oxidation kinetics and chemistry. To attain better knowledge of the compositional evolution of aqueous organic droplets during oxidation, this work investigates the heterogeneous OH-radical-initiated oxidation of aqueous methylsuccinic acid (C 5Hmore » 8O 4) droplets, a model compound for small branched dicarboxylic acids found in atmospheric aerosols, at a high relative humidity of 85 % through experimental and modeling approaches. Aerosol mass spectra measured by a soft atmospheric pressure ionization source (Direct Analysis in Real Time, DART) coupled with a high-resolution mass spectrometer reveal two major products: a five carbon atom (C 5) hydroxyl functionalization product (C 5H 8O 5) and a C 4 fragmentation product (C 4H 6O 3). These two products likely originate from the formation and subsequent reactions (intermolecular hydrogen abstraction and carbon–carbon bond scission) of tertiary alkoxy radicals resulting from the OH abstraction occurring at the methyl-substituted carbon site. Based on the identification of the reaction products, a kinetic model of oxidation (a two-product model) coupled with the Aerosol Inorganic–Organic Mixtures Functional groups Activity Coefficients (AIOMFAC) model is built to simulate the size and compositional changes of aqueous methylsuccinic acid droplets during oxidation. Model results show that at the maximum OH exposure, the droplets become slightly more hygroscopic after oxidation, as the mass fraction of water is predicted to increase from 0.362 to 0.424; however, the diameter of the droplets decreases by 6.1 %. This can be attributed to the formation of volatile fragmentation products that partition to the gas phase, leading to a net loss of organic species and associated particle-phase water, and thus a smaller droplet size. Overall, fragmentation and volatilization processes play a larger role than the functionalization process in determining the evolution of aerosol water content and droplet size at high-oxidation stages.« less

Self-nanoemulsifying drug delivery system for enhanced bioavailability and improved hepatoprotective activity of biphenyl dimethyl dicarboxylate.

PubMed

El-Laithy, Hanan M

2008-07-01

Biphenyl Dimethyl Dicarboxylate (BDD) is insoluble in aqueous solution and the bioavailability after oral administration is low. Self-nanoemulsifying drug delivery system (SNEDDS) containing BDD has been successfully prepared using carefully selected ingredients which are less affected by pH and ionic strength changes to improve its bioavailability. SNEDDS is an isotropic mixture of lipid, surfactant, and cosurfactant which are spontaneously emulsified in aqueous medium under gentle digestive motility in the gastrointestinal tract. Pseudo ternary phase diagrams composed of various excipients were plotted to identify self -nano -emulsifying area. Droplet size changes upon dilution with aqueous media and in vitro release of BDD from SNEDDS in 0.1N HCl and phosphate buffer (pH 7.4) were studied and compared with commercial chinese pilules and Pennel capsules. The hepatoprotective activity upon oral administration of SNEDDS against carbon tetrachloride-induced oxidative stress in albino rats was assessed by measuring biochemical parameters like serum glutamic oxalacetate transaminase (SGOT), serum glutamic pyruvate transaminase (SGPT) and lactate dehydrogenase (LDH). Results showed that using a proper ratio of Tween 80 to Transcutol as surfactant and co-surfactant respectively and Miglyol 812 as oil to surfactants mixture resulted in production of infinitely diluted formulations in nano droplet size range. BDD self nano emulsified formula composed of 20% Miglyol 812, 60% Tween 80 and 20% Transcutol released 99% of the drug very rapidly within 10-15 minutes regardless of the pH condition. The oral absorption and bioavailability of BDD self nano emulsified formula in albino rats were significantly enhanced (P<0.01) with an average improvement of 1.7 and 6-folds that of commercial chinese pilules and Pennel capsules respectively. This improvement was also confirmed histopathologically in chemically injured rats and by the significant decrease in elevated liver enzymes level.

Asphaltenes-based polymer nano-composites

DOEpatents

Bowen, III, Daniel E

2013-12-17

Inventive composite materials are provided. The composite is preferably a nano-composite, and comprises an asphaltene, or a mixture of asphaltenes, blended with a polymer. The polymer can be any polymer in need of altered properties, including those selected from the group consisting of epoxies, acrylics, urethanes, silicones, cyanoacrylates, vulcanized rubber, phenol-formaldehyde, melamine-formaldehyde, urea-formaldehyde, imides, esters, cyanate esters, allyl resins.

Polymer-Attached Functional Inorganic-Organic Hybrid Nano-Composite Aerogels

DTIC Science & Technology

2003-01-01

drugs. The chemistry to synthesize polyamino- siloxane based aerogel composite was discussed. In addition, two approaches to synthesize PHEMA aerogel... Composite Aerogels DISTRIBUTION: Approved for public release, distribution unlimited This paper is part of the following report: TITLE: Materials...Proc. Vol. 740 © 2003 Materials Research Society 112.24 Polymer-Attached Functional Inorganic-Organic Hybrid Nano- composite Aerogels Xipeng Liu, Mingzhe

Evaluation of shear bond strength of orthodontic brackets bonded with nano-filled composites.

PubMed

Chalipa, Javad; Akhondi, Mohammad Sadegh Ahmad; Arab, Sepideh; Kharrazifard, Mohammad Javad; Ahmadyar, Maryam

2013-09-01

The purpose of this study was to evaluate the shear bond strength (SBS) of orthodontic brackets bonded with two types of nano-composites in comparison to a conventional orthodontic composite. Sixty extracted human first premolars were randomly divided into 3 groups each containing 20 teeth. In group I, a conventional orthodontic composite (Transbond XT) was used to bond the brackets, while two nano-composites (Filtek TM Supreme XT and AELITE Aesthetic Enamel) were used in groups II and III respectively. The teeth were stored in distilled water at 37°C for 24 hours, thermocycled in distilled water and debonded with a universal testing machine at a crosshead speed of 1 mm/min. The adhesive remnant index (ARI) was also evaluated using a stereomicroscope. AELITE Aesthetic Enamel nano-composite revealed a SBS value of 8.44±2.09 MPa, which was higher than Transbond XT (6.91±2.13) and Filtek TM Supreme XT (6.04±2.01). Statistical analysis revealed a significant difference between groups II and III (P < 0.05). No significant difference was found between groups I and III, and between groups I and II (P > 0.05). Evaluation of ARI showed that Transbond XT left fewer adhesive remains on teeth after debonding. Results of this study indicate that the aforementioned nano-composites can be successfully used for bonding orthodontic brackets.

Wear and friction behavior of Al-TiB2-nano-Gr hybrid composites fabricated through ultrasonic cavitation assisted stir casting

NASA Astrophysics Data System (ADS)

Poria, Suswagata; Sutradhar, Goutam; Sahoo, Prasanta

2018-05-01

The present study reports the role of nano-graphite particles in determining wear and friction behavior of Al-TiB2-nano-Gr hybrid composites. Ultrasonic cavitation assisted stir casting method has been used for fabrication of composites. Al-Si5Cu3 alloy is used as base alloy along with micro sized TiB2 hard ceramic particles (2.5 and 5.5 wt%) as reinforcement and nano-Gr particles (2 and 4 wt%) as solid lubricant additives. SEM micrographs, EDAX spectrum and optical images are considered to observe uniform dispersion of reinforcing phases. Micro-hardness is evaluated using Vicker’s microhardness tester. Hardness is seen to increase with incorporation of TiB2 while the same decreases with incorporation of graphite. Wear and friction of composites are tested for varying load (10 to 40 N) and sliding speed (0.2 to 0.4 m s‑1) using a pin-on-disk tribometer. Worn surfaces are characterized using SEM and EDAX analysis. Wear resistance of composites increases with incorporation of reinforcing phases together. Nano-Gr particles are easily sheared out from the sub-surface and provide a layer over the tribo-surface of composite that enhances friction and wear behavior. Wear mechanism in composites is predominantly adhesion while abrasion and ploughing is prominent in base alloy.

Exploding dissipative solitons in the cubic-quintic complex Ginzburg-Landau equation in one and two spatial dimensions. A review and a perspective

NASA Astrophysics Data System (ADS)

Cartes, C.; Descalzi, O.; Brand, H. R.

2014-10-01

We review the work on exploding dissipative solitons in one and two spatial dimensions. Features covered include: the transition from modulated to exploding dissipative solitons, the analogue of the Ruelle-Takens scenario for dissipative solitons, inducing exploding dissipative solitons by noise, two classes of exploding dissipative solitons in two spatial dimensions, diffusing asymmetric exploding dissipative solitons as a model for a two-dimensional extended chaotic system. As a perspective we outline the interaction of exploding dissipative solitons with quasi one-dimensional dissipative solitons, breathing quasi one-dimensional solutions and their possible connection with experimental results on convection, and the occurence of exploding dissipative solitons in reaction-diffusion systems. It is a great pleasure to dedicate this work to our long-time friend Hans (Prof. Dr. Hans Jürgen Herrmann) on the occasion of his 60th birthday.

50th Annual Fuze Conference.Session 3 and 4

DTIC Science & Technology

2006-05-11

Exploding Foil Initiator Research • Research on Explosives • Conclusion Wim Prinse Research Scientist3 TNO has organised...Research Scientist6 Exploding Foil Initiator Research • Electrical circuit • Exploding foil • Velocity of the flyer • Driver Explosive • Secondary...90% efficiency of energy deposited in the exploding foil (50 % other circuits) Wim Prinse Research Scientist8 Exploding foil • Dimension of the foil

Surface morphology and improved electrical conductivity of camphorsulfonic acid surfactant based PANI nano composite

NASA Astrophysics Data System (ADS)

Niranjana, M.; Yesappa, L.; Ashokkumar, S. P.; Vijeth, H.; Devendrappa, H.

2018-05-01

Polyaniline and its composites at different wt. % of Copper oxide nano (PCC1 and PCC5) were prepared by in-situ chemical reaction method. The composites were characterized by Fourier Transform Infrared (FT-IR) Spectroscopy, Field Emission Scanning Electron Microscopy (FESEM) and the impedance measurement was carried out at different temperature. FTIR and SEM image reveals the presence of copper metal ions uniformly embedded into PANI. The dc electrical conductivity increases with increasing nano concentration in PANI and achieved high conductivity for PCC5. These results are suggesting PCC composite is a prominent candidate for supercapacitor properties and optoelectronics devices applications.

Studies on gallium nitride doped ferrite-polypyrrole nanocomposites

NASA Astrophysics Data System (ADS)

Indrakanti, Rajani; Brahmaji Rao, V.; Udaya Kiran, C.

2018-06-01

This communication reports the synthesis and characterisation of two novel Intrinsic conducting polymer nano composites (ICPN s) with the formulae Ga (2x+2) N Fe 2(49-x) O3—PPY synthesized using Impregnation technique. The Gallium nitride ferrite nano particles were synthesized for x = 1 and x = 5 using the above stichiometric equation earlier by Sol—Gel route. The chemical composition in the assembly of the ICPNs were Ga4NFe96O3-3%,10%,30% Polypyrrole, Ga12NFe88O3-3%,10%,30% Polypyrrole by weight. The Sci-Finder software failed to trace any earlier articles or reviews related to these ICNPs synthesised by us in the literature. X-ray Diffractometric (Structural), Morphological, EDAX SAED, IR spectroscopic characterizations were done on the synthesized nanocomposites. Structural studies reveal the semi-crystalline nature of composites. The average crystallite size of nano composites is decreased when compared with nano ferrites. SEM findings reveal that the shape for higher percentage of PPY is nano rods; for lower percentage it is globular. TEM reveals good dispersion and average particle size from histograms are calculated. The FT- IR bands of PPY and GaNFe2O3 are observed which show strong interaction between PPY- GaNFe2O3. Also there is a shift of bands in GaNFe2O3-PPY nano composites when compared to the bands of PPY.

Scalable Preparation of Ternary Hierarchical Silicon Oxide-Nickel-Graphite Composites for Lithium-Ion Batteries

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

Wang , Jing; Bao, Wurigumula; Ma, Lu

2015-11-09

Silicon monoxide is a promising anode candidate because of its high theoretical capacity and good cycle performance. To solve the problems associated with this material, including large volume changes during charge-discharge processes, we report a ternary hierarchical silicon oxide–nickel–graphite composite prepared by a facile two-step ball-milling method. The composite consists of nano-Si dispersed silicon oxides embedded in nano-Ni/graphite matrices (Si@SiOx/Ni/graphite). In the composite, crystalline nano-Si particles are generated by the mechanochemical reduction of SiO by ball milling with Ni. These nano-Si dispersed oxides have abundant electrochemical activity and can provide high Li-ion storage capacity. Furthermore, the milled nano-Ni/graphite matrices stickmore » well to active materials and interconnect to form a crosslinked framework, which functions as an electrical highway and a mechanical backbone so that all silicon oxide particles become electrochemically active. Owing to these advanced structural and electrochemical characteristics, the composite enhances the utilization efficiency of SiO, accommodates its large volume expansion upon cycling, and has good ionic and electronic conductivity. The composite electrodes thus exhibit substantial improvements in electrochemical performance. This ternary hierarchical Si@SiOx/Ni/graphite composite is a promising candidate anode material for high-energy lithium-ion batteries. Additionally, the mechanochemical ball-milling method is low cost and easy to reproduce, indicating potential for the commercial production of the composite materials.« less

Scalable Preparation of Ternary Hierarchical Silicon Oxide-Nickel-Graphite Composites for Lithium-Ion Batteries.

PubMed

Wang, Jing; Bao, Wurigumula; Ma, Lu; Tan, Guoqiang; Su, Yuefeng; Chen, Shi; Wu, Feng; Lu, Jun; Amine, Khalil

2015-12-07

Silicon monoxide is a promising anode candidate because of its high theoretical capacity and good cycle performance. To solve the problems associated with this material, including large volume changes during charge-discharge processes, we report a ternary hierarchical silicon oxide-nickel-graphite composite prepared by a facile two-step ball-milling method. The composite consists of nano-Si dispersed silicon oxides embedded in nano-Ni/graphite matrices (Si@SiOx /Ni/graphite). In the composite, crystalline nano-Si particles are generated by the mechanochemical reduction of SiO by ball milling with Ni. These nano-Si dispersed oxides have abundant electrochemical activity and can provide high Li-ion storage capacity. Furthermore, the milled nano-Ni/graphite matrices stick well to active materials and interconnect to form a crosslinked framework, which functions as an electrical highway and a mechanical backbone so that all silicon oxide particles become electrochemically active. Owing to these advanced structural and electrochemical characteristics, the composite enhances the utilization efficiency of SiO, accommodates its large volume expansion upon cycling, and has good ionic and electronic conductivity. The composite electrodes thus exhibit substantial improvements in electrochemical performance. This ternary hierarchical Si@SiOx /Ni/graphite composite is a promising candidate anode material for high-energy lithium-ion batteries. Additionally, the mechanochemical ball-milling method is low cost and easy to reproduce, indicating potential for the commercial production of the composite materials. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Investigating NO2 gas sensing behavior of flower-like MoS2 and rGO based nano-composite

NASA Astrophysics Data System (ADS)

Kanaujiya, Neha; Anupam, Golimar, Kapil; Pandey, Prateek Chandra; Jyoti, Varma, G. D.

2018-05-01

In the present work, MoS2 nano-sheets with flower-like morphology have been synthesized by facile hydrothermal method. The nano-composite of MoS2 and reduced graphene oxide (rGO) nano-sheets has been synthesized to study the gas sensing behavior. The structural and morphological characteristics of the as prepared samples are investigated by X-ray diffraction (XRD) and Field emission scanning electron microscopy (FESEM) respectively. The gas sensing behavior of the as synthesized MoS2 and composite samples have been studied for different concentrations of NO2 at different temperatures. Improvement in sensing response of composite sample as compared to bare MoS2 sample has been observed. Percentage response of ˜ 23% has been observed at room temperature for 40ppm NO2. The detail correlation between gas sensing behavior and structural characteristics of the composite sample will be described and discussed in this paper.

Droplet microfluidic technology for single-cell high-throughput screening.

PubMed

Brouzes, Eric; Medkova, Martina; Savenelli, Neal; Marran, Dave; Twardowski, Mariusz; Hutchison, J Brian; Rothberg, Jonathan M; Link, Darren R; Perrimon, Norbert; Samuels, Michael L

2009-08-25

We present a droplet-based microfluidic technology that enables high-throughput screening of single mammalian cells. This integrated platform allows for the encapsulation of single cells and reagents in independent aqueous microdroplets (1 pL to 10 nL volumes) dispersed in an immiscible carrier oil and enables the digital manipulation of these reactors at a very high-throughput. Here, we validate a full droplet screening workflow by conducting a droplet-based cytotoxicity screen. To perform this screen, we first developed a droplet viability assay that permits the quantitative scoring of cell viability and growth within intact droplets. Next, we demonstrated the high viability of encapsulated human monocytic U937 cells over a period of 4 days. Finally, we developed an optically-coded droplet library enabling the identification of the droplets composition during the assay read-out. Using the integrated droplet technology, we screened a drug library for its cytotoxic effect against U937 cells. Taken together our droplet microfluidic platform is modular, robust, uses no moving parts, and has a wide range of potential applications including high-throughput single-cell analyses, combinatorial screening, and facilitating small sample analyses.

Improving the corrosion wear resistance of AISI 316L stainless steel by particulate reinforced Ni matrix composite alloying layer

NASA Astrophysics Data System (ADS)

Xu, Jiang; Zhuo, Chengzhi; Tao, Jie; Jiang, Shuyun; Liu, Linlin

2009-01-01

In order to overcome the problem of corrosion wear of AISI 316L stainless steel (SS), two kinds of composite alloying layers were prepared by a duplex treatment, consisting of Ni/nano-SiC and Ni/nano-SiO2 predeposited by brush plating, respectively, and subsequent surface alloying with Ni-Cr-Mo-Cu by a double glow process. The microstructure of the two kinds of nanoparticle reinforced Ni-based composite alloying layers was investigated by means of SEM and TEM. The electrochemical corrosion behaviour of composite alloying layers compared with the Ni-based alloying layer and 316L SS under different conditions was characterized by potentiodynamic polarization test and electrochemical impedance spectroscopy. Results showed that under alloying temperature (1000 °C) conditions, amorphous nano-SiO2 particles still retained the amorphous structure, whereas nano-SiC particles were decomposed and Ni, Cr reacted with SiC to form Cr6.5Ni2.5Si and Cr23C6. In static acidic solution, the corrosion resistance of the composite alloying layer with the brush plating Ni/nano-SiO2 particles interlayer is lower than that of the Ni-based alloying layer. However, the corrosion resistance of the composite alloying layer with the brush plating Ni/nano-SiO2 particles interlayer is prominently superior to that of the Ni-based alloying layer under acidic flow medium condition and acidic slurry flow condition. The corrosion resistance of the composite alloying layer with the brush plating Ni/nano-SiC particles interlayer is evidently lower than that of the Ni-based alloying layer, but higher than that of 316L SS under all test conditions. The results show that the highly dispersive nano-SiO2 particles are helpful in improving the corrosion wear resistance of the Ni-based alloying layer, whereas carbides and silicide phase are deleterious to that of the Ni-based alloying layer due to the fact that the preferential removal of the matrix around the precipitated phase takes place by the chemical attack of an aggressive medium.

Performance of glucose/O2 enzymatic fuel cell based on supporting electrodes over-coated by polymer-nanogold particle composite with entrapped enzymes

NASA Astrophysics Data System (ADS)

Huo, W. S.; Zeng, H.; Yang, Y.; Zhang, Y. H.

2017-03-01

Enzymatic electrodes over-coated by thin film of nano-composite made up of polymer and functionalized nano-gold particle was prepared. Glucose/O2 membrane-free enzymatic fuel cell based on nano-composite based electrodes with incorporated glucose oxidase and laccase was assembled. This enzymatic fuel cell exhibited high energy out-put density even when applied in human serum. Catalytic cycle involved in enzymatic fuel cell was limited by oxidation of glucose occurred on bioanode resulting from impact of sophisticated interaction between active site in glucose oxidase and nano-gold particle on configuration of redox center of enzyme molecule which crippled catalytic efficiency of redox protein.

Synthesis and photocatalytic activity of sepiolite supportednano-TiO2 composites prepared by a mild solid-state sintering process

NASA Astrophysics Data System (ADS)

Liao, L. M.; Wang, Z. Q.; Liang, H.; Feng, J.; Zhang, D.

2016-08-01

Supported nano-TiO2photocatalysts play an important role in water environment restoration because of their potential application to photocatalytic degradation of organic contaminants in waste water. With sepiolite as the support, the nano-TiO2/sepiolite composite photocatalysts were synthesized by an easily operated and mild solid-state sintering process.The microstructureand photocatalytic property of the sepiolite supportednano-TiO2 composites were characterized and analyzed by X-ray diffraction spectroscopy, UV-Visible spectroscopy and fluorescence spectroscopy. In addition, the influences of calcination temperature and load ratios on the photocatalytic activity of sepiolite supported nano-TiO2 composites were studied.The results indicated that appropriate ratios of sepiolite supports to nano-TiO2contributed to uniform dispersion of nanoparticles, and enhanced the absorption ability within the UV-Vis range, and consequently increased the photocatalytic activity of the composites.Under the preparation conditions of 90 wt. % TiO2 loading and calcinated at 400 °C, a maximum in photocatalytic activity ofnano-TiO2 sepiolite composite was obtained.

Improvement of silicone rubber properties by addition of nano-SiO2 particles.

PubMed

Wu, Lianfeng; Wang, Xianming; Ning, Liang; Han, Jianjun; Wan, Zhong; Lu, Min

2016-07-04

To improve the comprehensive performances of a one-part room temperature vulcanized silicone rubber(RTV-1 SiR), Nano-SiO2 particles are employed as the reinforcing agent. The SiO2/RTV-1 SiR composite is prepared using PDMS, ND42, D-60 and HMDS-modified SiO2 particles by mixing method. And then, the mechanical and electrical properties, including shear strength, tensile strength, hardness Shore A and volume resistivity, are investigated using experimental method. The addition of nano-SiO2 particles can improve the properties of the SiO2/RTV-1 SiR composite in different degrees. And, the incorporation of 25~30 phr nano-SiO2 particles is found to be reasonable for silicone rubber composite with the best comprehensive performances. The significant improvement of mechanical properties and electrical insulation of SiO2 may be contributed to the addition of modified nano-SiO2 particles. Additionally, the excellent comprehensive performances of SiO2/RTV-1 SiR composite guarantee a potential applications as electrical-insulating adhesives.

Preparation and characterization of PVP-PVA–ZnO blend polymer nano composite films

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

Divya, S., E-mail: divi.fysics@gmail.com; Saipriya, G.; Hemalatha, J., E-mail: hemalatha@nitt.edu

Flexible self-standing films of PVP-PVA blend composites are prepared by using ZnO as a nano filler at different concentrations. The structural, compositional, morphological and optical studies made with the help of X-ray diffraction (XRD), Fourier Transform Infra-Red spectroscopy (FTIR), Scanning electron microscope (SEM), Atomic Force Microscopy (AFM), Ultraviolet-visible spectroscopy (UV-vis) and Photoluminescence (PL) spectra are presented in this paper. The results of XRD indicate that ZnO nanoparticles are formed with hexagonal phase in the polymeric matrix. SEM images show the dispersion of ZnO nano filler in the polymer matrix. UV–vis spectra reveal that the absorption peak is centered around 235more » nm and 370 nm for the nano composite films. The blue shift is observed with decrease in the concentration of the nano filler. PL spectra shows the excitation wavelength is given at 320 nm.The emission peaks were observed at 383 nm ascribing to the electronic transitions between valence band and conduction band and the peak at 430 nm.« less

[Histocompatibility of nano-hydroxyapatite/poly-co-glycolic acid tissue engineering bone modified by mesenchymal stem cells with vascular endothelial frowth factor].

PubMed

Zhang, Minglei; Wang, Dapeng; Yin, Ruofeng

2015-10-06

To explorec Histocompatibility of nano-hydroxyapatite/poly-co-glycolic acid tissue engineering bone modified by mesenchymal stem cells with vascular endothelial frowth factor transinfected. Rat bone marrow mesenchymal stem cells (BMSCs) was separated, using BMSCs as target cells, and then vascular endothelial growth factor (VEGF) gene was transfected. Composite bone marrow mesenchymal stem cells and cells transfected with nano-hydroxyapatite (HA)/polylactic-co-glycolic acid (PLGA). The composition of cell and scaffold was observed. The blank plasmid transfection was 39.1%, 40.1% in VEGF group. The cell adhesion and growth was found on the scaffold pore wall after 5 days, and the number of adherent cells in the nano-HA/PLGA composite scaffold material basically had no significant difference in both. Although the nano-HA/PLGA scaffold material is still not fully meet the requirements of the matrix material for bone tissue engineering, but good biocompatibility, structure is its rich microporous satisfaction in material mechanics, toughening, enhanced obviously. Composition scaffold with BMSCs transfected by VEGF plasmid, the ability of angiogenesis is promoted.

Electrophoretic deposition of hydroxyapatite-hexagonal boron nitride composite coatings on Ti substrate.

PubMed

Göncü, Yapıncak; Geçgin, Merve; Bakan, Feray; Ay, Nuran

2017-10-01

In this study, commercial pure titanium samples were coated with nano hydroxyapatite-nano hexagonal boron nitride (nano HA-nano hBN) composite by electrophoretic deposition (EPD). The effect of process parameters (applied voltage, deposition time and solid concentration) on the coating morphology, thickness and the adhesion behavior were studied systematically and crack free nano hBN-nano HA composite coating production was achieved for developing bioactive coatings on titanium substrates for orthopedic applications. For the examination of structural and morphological characteristics of the coating surfaces, various complementary analysis methods were performed. For the structural characterization, XRD and Raman Spectroscopy were used while, Scanning Electron Microscopy (SEM) equipped with an energy dispersive spectrometer (EDS) and Transmission Electron Microscopy (TEM) techniques were carried out for revealing the morphological characterization. The results showed that nano HA-nano hBN were successfully deposited on Ti surface with uniform, crack-free coating by EPD. The amounts of hBN in suspension are considered to have no effect on coating thickness. By adding hBN into HA, the morphology of HA did not change and hBN has no significant effect on porous structure. These nanostructured surfaces are expected to be suitable for proliferation of cells and have high potential for bioactive materials. Copyright © 2017 Elsevier B.V. All rights reserved.

Slow relaxation mode in concentrated oil-in-water microemulsions consisting of repulsive droplets

NASA Astrophysics Data System (ADS)

Hattori, Y.; Ushiki, H.; Courbin, L.; Panizza, P.

2007-02-01

The present contribution reports on the observation of two diffusive relaxation modes in a concentrated microemulsion made of repulsive droplets. These two modes can be interpreted in the frame of Weissman’s and Pusey’s theoretical pioneering works. The fast mode is associated to the collective diffusion of droplets whereas the slow one corresponds to the relaxation of droplet concentration fluctuations associated with composition and/or size. We show that (i) repulsive interactions considerably slow down the latter and (ii) a generalized Stokes Einstein relationship between its coefficient of diffusion and the Newtonian viscosity of the solutions, similar to the Walden’s rule for electrolytes, holds for concentrated microemulsion systems made of repulsive droplets.

Characterization of mechanical properties of hydroxyapatite-silicon-multi walled carbon nano tubes composite coatings synthesized by EPD on NiTi alloys for biomedical application.

PubMed

Khalili, Vida; Khalil-Allafi, Jafar; Sengstock, Christina; Motemani, Yahya; Paulsen, Alexander; Frenzel, Jan; Eggeler, Gunther; Köller, Manfred

2016-06-01

Release of Ni(1+) ions from NiTi alloy into tissue environment, biological response on the surface of NiTi and the allergic reaction of atopic people towards Ni are challengeable issues for biomedical application. In this study, composite coatings of hydroxyapatite-silicon multi walled carbon nano-tubes with 20wt% Silicon and 1wt% multi walled carbon nano-tubes of HA were deposited on a NiTi substrate using electrophoretic methods. The SEM images of coated samples exhibit a continuous and compact morphology for hydroxyapatite-silicon and hydroxyapatite-silicon-multi walled carbon nano-tubes coatings. Nano-indentation analysis on different locations of coatings represents the highest elastic modulus (45.8GPa) for HA-Si-MWCNTs which is between the elastic modulus of NiTi substrate (66.5GPa) and bone tissue (≈30GPa). This results in decrease of stress gradient on coating-substrate-bone interfaces during performance. The results of nano-scratch analysis show the highest critical distance of delamination (2.5mm) and normal load before failure (837mN) as well as highest critical contact pressure for hydroxyapatite-silicon-multi walled carbon nano-tubes coating. The cell culture results show that human mesenchymal stem cells are able to adhere and proliferate on the pure hydroxyapatite and composite coatings. The presence of both silicon and multi walled carbon nano-tubes (CS3) in the hydroxyapatite coating induce more adherence of viable human mesenchymal stem cells in contrast to the HA coated samples with only silicon (CS2). These results make hydroxyapatite-silicon-multi walled carbon nano-tubes a promising composite coating for future bone implant application. Copyright © 2016 Elsevier Ltd. All rights reserved.

Co-Compartmentation of Terpene Biosynthesis and Storage via Synthetic Droplet.

PubMed

Zhao, Cheng; Kim, YongKyoung; Zeng, Yining; Li, Man; Wang, Xin; Hu, Cheng; Gorman, Connor; Dai, Susie Y; Ding, Shi-You; Yuan, Joshua S

2018-03-16

Traditional bioproduct engineering focuses on pathway optimization, yet is often complicated by product inhibition, downstream consumption, and the toxicity of certain products. Here, we present the co-compartmentation of biosynthesis and storage via a synthetic droplet as an effective new strategy to improve the bioproduct yield, with squalene as a model compound. A hydrophobic protein was designed and introduced into the tobacco chloroplast to generate a synthetic droplet for terpene storage. Simultaneously, squalene biosynthesis enzymes were introduced to chloroplasts together with the droplet-forming protein to co-compartmentalize the biosynthesis and storage of squalene. The strategy has enabled a record yield of squalene at 2.6 mg/g fresh weight without compromising plant growth. Confocal fluorescent microscopy imaging, stimulated Raman scattering microscopy, and droplet composition analysis confirmed the formation of synthetic storage droplet in chloroplast. The co-compartmentation of synthetic storage droplet with a targeted metabolic pathway engineering represents a new strategy for enhancing bioproduct yield.

Formation of Core-Shell Ethane-Silver Clusters in He Droplets.

PubMed

Loginov, Evgeny; Gomez, Luis F; Sartakov, Boris G; Vilesov, Andrey F

2017-08-17

Ethane core-silver shell clusters consisting of several thousand particles have been assembled in helium droplets upon capture of ethane molecules followed by Ag atoms. The composite clusters were studied via infrared laser spectroscopy in the range of the C-H stretching vibrations of ethane. The spectra reveal a splitting of the vibrational bands, which is ascribed to interaction with Ag. A rigorous analysis of band intensities for a varying number of trapped ethane molecules and Ag atoms indicates that the composite clusters consist of a core of ethane that is covered by relatively small Ag clusters. This metastable structure is stabilized due to fast dissipation in superfluid helium droplets of the cohesion energy of the clusters.

Methods Development for Blood Borne Macrophage Carriage of Nanoformulated Antiretroviral Drugs

PubMed Central

Roy, Upal; Martinez-Skinner, Andrea; McMillan, JoEllyn; Gendelman, Howard E.

2010-01-01

Nanoformulated drugs can improve pharmacodynamics and bioavailability while serving also to reduce drug toxicities for antiretroviral (ART) medicines. To this end, our laboratory has applied the principles of nanomedicine to simplify ART regimens and as such reduce toxicities while improving compliance and drug pharmacokinetics. Simple and reliable methods for manufacturing nanoformulated ART (nanoART) are shown. Particles of pure drug are encapsulated by a thin layer of surfactant lipid coating and produced by fractionating larger drug crystals into smaller ones by either wet milling or high-pressure homogenization. In an alternative method free drug is suspended in a droplet of a polymer. Herein, drug is dissolved within a polymer then agitated by ultrasonication until individual nanosized droplets are formed. Dynamic light scattering and microscopic examination characterize the physical properties of the particles (particle size, charge and shape). Their biologic properties (cell uptake and retention, cytotoxicity and antiretroviral efficacy) are determined with human monocyte-derived macrophages (MDM). MDM are derived from human peripheral blood monocytes isolated from leukopacks using centrifugal elutriation for purification. Such blood-borne macrophages may be used as cellular transporters for nanoART distribution to human immunodeficiency virus (HIV) infected organs. We posit that the repackaging of clinically available antiretroviral medications into nanoparticles for HIV-1 treatments may improve compliance and positively affect disease outcomes. PMID:21178968

Magnetic stage with environmental control for optical microscopy and high-speed nano- and microrheology

NASA Astrophysics Data System (ADS)

Aprelev, Pavel; McKinney, Bonni; Walls, Chadwick; Kornev, Konstanin G.

2017-07-01

A novel design of a low-field magnetic stage for optical microscopy of droplets and films within a controlled environment is described. The stage consists of five magnetic coils with a 3D magnetic sensor in a feedback control loop, which allows one to manipulate magnetic nano- and microprobes with microtesla fields. A locally uniform time-dependent field within the focal plane of the microscope objective enables one to rotate the probes in a precisely set manner and observe their motion. The probe tracking protocol was developed to follow the probe rotation in real time and relate it with the viscosity of the host liquid. Using this magnetic stage, a method for measuring mPa s-level viscosity of nanoliter droplets and micron thick films in a 10-20 s timeframe is presented and validated. The viscosity of a rapidly changing liquid can be tracked by using only a few visible probes rotating simultaneously. Vapor pressure and temperature around the sample can be controlled to directly measure viscosity as a function of equilibrium vapor pressure; this addresses a significant challenge in characterization of volatile nanodroplets and thin films. Thin films of surfactant solutions undergoing phase transitions upon solvent evaporation were studied and their rheological properties were related to morphological changes in the material.

Oil Contact Angles in a Water-Decane-Silicon Dioxide System: Effects of Surface Charge

NASA Astrophysics Data System (ADS)

Xu, Shijing; Wang, Jingyao; Wu, Jiazhong; Liu, Qingjie; Sun, Chengzhen; Bai, Bofeng

2018-04-01

Oil wettability in the water-oil-rock systems is very sensitive to the evolution of surface charges on the rock surfaces induced by the adsorption of ions and other chemical agents in water flooding. Through a set of large-scale molecular dynamics simulations, we reveal the effects of surface charge on the oil contact angles in an ideal water-decane-silicon dioxide system. The results show that the contact angles of oil nano-droplets have a great dependence on the surface charges. As the surface charge density exceeds a critical value of 0.992 e/nm2, the contact angle reaches up to 78.8° and the water-wet state is very apparent. The variation of contact angles can be confirmed from the number density distributions of oil molecules. With increasing the surface charge density, the adsorption of oil molecules weakens and the contact areas between nano-droplets and silicon dioxide surface are reduced. In addition, the number density distributions, RDF distributions, and molecular orientations indicate that the oil molecules are adsorbed on the silicon dioxide surface layer-by-layer with an orientation parallel to the surface. However, the layered structure of oil molecules near the silicon dioxide surface becomes more and more obscure at higher surface charge densities.

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

NASA Astrophysics Data System (ADS)

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

2018-06-01

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

Experimental and theoretical studies of light-to-heat conversion and collective heating effects in metal nanoparticle solutions.

PubMed

Richardson, Hugh H; Carlson, Michael T; Tandler, Peter J; Hernandez, Pedro; Govorov, Alexander O

2009-03-01

We perform a set of experiments on photoheating in a water droplet containing gold nanoparticles (NPs). Using photocalorimetric methods, we determine efficiency of light-to-heat conversion (eta) which turns out to be remarkably close to 1, (0.97 < eta < 1.03). Detailed studies reveal a complex character of heat transfer in an optically stimulated droplet. The main mechanism of equilibration is due to convectional flow. Theoretical modeling is performed to describe thermal effects at both nano- and millimeter scales. Theory shows that the collective photoheating is the main mechanism. For a large concentration of NPs and small laser intensity, an averaged temperature increase (at the millimeter scale) is significant (approximately 7 degrees C), whereas on the nanometer scale the temperature increase at the surface of a single NP is small (approximately 0.02 degrees C). In the opposite regime, that is, a small NP concentration and intense laser irradiation, we find an opposite picture: a temperature increase at the millimeter scale is small (0.1 degrees C) but a local, nanoscale temperature has strong local spikes at the surfaces of NPs (approximately 3 degrees C). These studies are crucial for the understanding of photothermal effects in NPs and for their potential and current applications in nano- and biotechnologies.

Oil Contact Angles in a Water-Decane-Silicon Dioxide System: Effects of Surface Charge.

PubMed

Xu, Shijing; Wang, Jingyao; Wu, Jiazhong; Liu, Qingjie; Sun, Chengzhen; Bai, Bofeng

2018-04-19

Oil wettability in the water-oil-rock systems is very sensitive to the evolution of surface charges on the rock surfaces induced by the adsorption of ions and other chemical agents in water flooding. Through a set of large-scale molecular dynamics simulations, we reveal the effects of surface charge on the oil contact angles in an ideal water-decane-silicon dioxide system. The results show that the contact angles of oil nano-droplets have a great dependence on the surface charges. As the surface charge density exceeds a critical value of 0.992 e/nm 2 , the contact angle reaches up to 78.8° and the water-wet state is very apparent. The variation of contact angles can be confirmed from the number density distributions of oil molecules. With increasing the surface charge density, the adsorption of oil molecules weakens and the contact areas between nano-droplets and silicon dioxide surface are reduced. In addition, the number density distributions, RDF distributions, and molecular orientations indicate that the oil molecules are adsorbed on the silicon dioxide surface layer-by-layer with an orientation parallel to the surface. However, the layered structure of oil molecules near the silicon dioxide surface becomes more and more obscure at higher surface charge densities.

The Detection Rate of Early UV Emission from Supernovae: A Dedicated Galex/PTF Survey and Calibrated Theoretical Estimates

NASA Astrophysics Data System (ADS)

Ganot, Noam; Gal-Yam, Avishay; Ofek, Eran. O.; Sagiv, Ilan; Waxman, Eli; Lapid, Ofer; Kulkarni, Shrinivas R.; Ben-Ami, Sagi; Kasliwal, Mansi M.; The ULTRASAT Science Team; Chelouche, Doron; Rafter, Stephen; Behar, Ehud; Laor, Ari; Poznanski, Dovi; Nakar, Ehud; Maoz, Dan; Trakhtenbrot, Benny; WTTH Consortium, The; Neill, James D.; Barlow, Thomas A.; Martin, Christofer D.; Gezari, Suvi; the GALEX Science Team; Arcavi, Iair; Bloom, Joshua S.; Nugent, Peter E.; Sullivan, Mark; Palomar Transient Factory, The

2016-03-01

The radius and surface composition of an exploding massive star, as well as the explosion energy per unit mass, can be measured using early UV observations of core-collapse supernovae (SNe). We present the first results from a simultaneous GALEX/PTF search for early ultraviolet (UV) emission from SNe. Six SNe II and one Type II superluminous SN (SLSN-II) are clearly detected in the GALEX near-UV (NUV) data. We compare our detection rate with theoretical estimates based on early, shock-cooling UV light curves calculated from models that fit existing Swift and GALEX observations well, combined with volumetric SN rates. We find that our observations are in good agreement with calculated rates assuming that red supergiants (RSGs) explode with fiducial radii of 500 R ⊙, explosion energies of 1051 erg, and ejecta masses of 10 M ⊙. Exploding blue supergiants and Wolf-Rayet stars are poorly constrained. We describe how such observations can be used to derive the progenitor radius, surface composition, and explosion energy per unit mass of such SN events, and we demonstrate why UV observations are critical for such measurements. We use the fiducial RSG parameters to estimate the detection rate of SNe during the shock-cooling phase (<1 day after explosion) for several ground-based surveys (PTF, ZTF, and LSST). We show that the proposed wide-field UV explorer ULTRASAT mission is expected to find >85 SNe per year (˜0.5 SN per deg2), independent of host galaxy extinction, down to an NUV detection limit of 21.5 mag AB. Our pilot GALEX/PTF project thus convincingly demonstrates that a dedicated, systematic SN survey at the NUV band is a compelling method to study how massive stars end their life.

[Study on the antibacterial activity of four kinds of nano-hydroxyapatite composites against Enterococcus faecalis].

PubMed

Liu, Yi; Zhou, Rongjing; Wu, Hongkun

2015-06-01

This study aims to compare and determine a kind of nano-hydroxyapatite composite material with good antibacterial efficacy on Enterococcusfaecalis (E. faecalis) in vitro. We investigated the antimicrobial activity of four kinds of nano-hydroxyapatite composites, namely, silver/hydroxyapatite composite nanoparticles (Ag/nHA), yttrium/hydroxyapatite composite nanoparticles (Yi/nHA), cerium/hydroxyapatite composite nanoparticles (Ce/nHA), and hydroxyapatite nanoparticles (nHA), against E. faecalis in vitro using the agar diffusion and broth dilution method by measuring the growth inhibition zone and the minimum inhibitory concentration (MIC), respectively. The agar diffusion test results showed that Ag/nHA displayed an obvious growth inhibition zone, whereas Yi/nHA, Ce/nHA, and nHA showed no influence on E. faecalis. The MIC value of Ag/nHA was 1.0 g.L-1, and the three other materials had no effect on E.faecalis even at the high concentration of 32.0 g.L-1. Ag/nHA display a potential antimicrobial efficacy to planktonic E.faecalis. Whereas, the three other kinds of nano-hydroxyapatite composites (Yi/nHA, Ce/nHA, nHA) show no influence.

Contrasting cloud composition between coupled and decoupled marine boundary layer clouds

NASA Astrophysics Data System (ADS)

Wang, Zhen; Mora Ramirez, Marco; Dadashazar, Hossein; MacDonald, Alex B.; Crosbie, Ewan; Bates, Kelvin H.; Coggon, Matthew M.; Craven, Jill S.; Lynch, Peng; Campbell, James R.; Azadi Aghdam, Mojtaba; Woods, Roy K.; Jonsson, Haflidi; Flagan, Richard C.; Seinfeld, John H.; Sorooshian, Armin

2016-10-01

Marine stratocumulus clouds often become decoupled from the vertical layer immediately above the ocean surface. This study contrasts cloud chemical composition between coupled and decoupled marine stratocumulus clouds for dissolved nonwater substances. Cloud water and droplet residual particle composition were measured in clouds off the California coast during three airborne experiments in July-August of separate years (Eastern Pacific Emitted Aerosol Cloud Experiment 2011, Nucleation in California Experiment 2013, and Biological and Oceanic Atmospheric Study 2015). Decoupled clouds exhibited significantly lower air-equivalent mass concentrations in both cloud water and droplet residual particles, consistent with reduced cloud droplet number concentration and subcloud aerosol (Dp > 100 nm) number concentration, owing to detachment from surface sources. Nonrefractory submicrometer aerosol measurements show that coupled clouds exhibit higher sulfate mass fractions in droplet residual particles, owing to more abundant precursor emissions from the ocean and ships. Consequently, decoupled clouds exhibited higher mass fractions of organics, nitrate, and ammonium in droplet residual particles, owing to effects of long-range transport from more distant sources. Sodium and chloride dominated in terms of air-equivalent concentration in cloud water for coupled clouds, and their mass fractions and concentrations exceeded those in decoupled clouds. Conversely, with the exception of sea-salt constituents (e.g., Cl, Na, Mg, and K), cloud water mass fractions of all species examined were higher in decoupled clouds relative to coupled clouds. Satellite and Navy Aerosol Analysis and Prediction System-based reanalysis data are compared with each other, and the airborne data to conclude that limitations in resolving boundary layer processes in a global model prevent it from accurately quantifying observed differences between coupled and decoupled cloud composition.

50th Annual Fuze Conference Sessions 3 and 4 Held in Norfolk, Virginia on May 9-11, 2006

DTIC Science & Technology

2006-05-11

Exploding Foil Initiator Research • Research on Explosives • Conclusion Wim Prinse Research Scientist3 TNO has organised...Research Scientist6 Exploding Foil Initiator Research • Electrical circuit • Exploding foil • Velocity of the flyer • Driver Explosive • Secondary...90% efficiency of energy deposited in the exploding foil (50 % other circuits) Wim Prinse Research Scientist8 Exploding foil • Dimension of the foil

Exploding conducting film laser pumping apparatus

DOEpatents

Ware, K.D.; Jones, C.R.

1984-04-27

The 342-nm molecular iodine and the 1.315-..mu..m atomic iodine lasers have been optically pumped by intense light from exploding-metal-film discharges. Brightness temperatures for the exploding-film discharges were approximately 25,000 K. Although lower output energies were achieved for such discharges when compared to exploding-wire techniques, the larger surface area and smaller inductance inherent in the exploding-film should lead to improved efficiency for optically-pumped gas lasers.

Development and characterization of sugarcane bagasse fiber and nano-silica reinforced epoxy hybrid composites

NASA Astrophysics Data System (ADS)

Fong, A. L.; Khandoker, N. A. N.; Debnath, S.

2018-04-01

This paper presents an experimental study on the mechanical performance of sugarcane bagasse fiber reinforced epoxy composite. Tensile and flexural properties of the composites were investigated in this research. Different weightage of short fiber and fiber particulates were utilized to study their effects on the mechanical performance of the composites in terms of tensile and flexural properties. 1% of nano-silica was reinforced to investigate its effect on the mechanical performance of the composites. Hand lay-up composite molding process was used to fabricate the composite samples. During fabrication, ultrasonic mixing was carried out to study the effects on mechanical performance of the fiber particulate reinforced composites. In overall, ultrasonic mixing and addition of nano-silica particles has improved the mechanical performance of the fiber particulate composites. Morphology analysis on surface of composites has shown the removal of air bubbles and deagglomeration. 1wt% of short fiber reinforced composite exhibits the highest tensile and flexural properties among all the samples. Sugarcane bagasse particulates reinforced composites were shown to have better performance compared to short fiber reinforced composites when the wt% of the fiber increase.

Alterations in the endometrium of rats, rabbits, and Macaca mulatta that received an implantation of copper/low-density polyethylene nanocomposite

PubMed Central

Hu, Li-Xia; Wang, Hong; Rao, Meng; Zhao, Xiao-Ling; Yang, Jing; Hu, Shi-Fu; He, Jing; Xia, Wei; Liu, Hefang; Zhen, Bo; Di, Haihong; Xie, Changsheng; Xia, Xianping; Zhu, Changhong

2014-01-01

A copper/low-density polyethylene nanocomposite (nano-Cu/LDPE), a potential intrauterine device component material, has been developed from our research. A logical extension of our previous work, this study was conducted to investigate the expression of plasminogen activator inhibitor 1 (PAI-1), substance P (SP), and substance P receptor (SP-R) in the endometrium of Sprague Dawley rats, New Zealand White rabbits, and Macaca mulatta implanted with nano-Cu/LDPE composite. The influence of the nano-Cu/LDPE composite on the morphology of the endometrium was also investigated. Animals were randomly divided into five groups: the sham-operated control group (SO group), bulk copper group (Cu group), LDPE group, and nano-Cu/LDPE groups I and II. An expression of PAI-1, SP, and SP-R in the endometrial tissues was examined by immunohistochemistry at day 30, 60, 90, and 180 postimplantation. The significant difference for PAI-1, SP, and SP-R between the nano-Cu/LDPE groups and the SO group (P<0.05) was identified when the observation period was terminated, and the changes of nano-Cu/LDPE on these parameters were less remarkable than those of the Cu group (P<0.05). The damage to the endometrial morphology caused by the nano-Cu/LDPE composite was much less than that caused by bulk copper. The nano-Cu/LDPE composite might be a potential substitute for conventional materials for intrauterine devices in the future because of its decreased adverse effects on the endometrial microenvironment. PMID:24596465

Alterations in the endometrium of rats, rabbits, and Macaca mulatta that received an implantation of copper/low-density polyethylene nanocomposite.

PubMed

Hu, Li-Xia; Wang, Hong; Rao, Meng; Zhao, Xiao-Ling; Yang, Jing; Hu, Shi-Fu; He, Jing; Xia, Wei; Liu, Hefang; Zhen, Bo; Di, Haihong; Xie, Changsheng; Xia, Xianping; Zhu, Changhong

2014-01-01

A copper/low-density polyethylene nanocomposite (nano-Cu/LDPE), a potential intrauterine device component material, has been developed from our research. A logical extension of our previous work, this study was conducted to investigate the expression of plasminogen activator inhibitor 1 (PAI-1), substance P (SP), and substance P receptor (SP-R) in the endometrium of Sprague Dawley rats, New Zealand White rabbits, and Macaca mulatta implanted with nano-Cu/LDPE composite. The influence of the nano-Cu/LDPE composite on the morphology of the endometrium was also investigated. Animals were randomly divided into five groups: the sham-operated control group (SO group), bulk copper group (Cu group), LDPE group, and nano-Cu/LDPE groups I and II. An expression of PAI-1, SP, and SP-R in the endometrial tissues was examined by immunohistochemistry at day 30, 60, 90, and 180 postimplantation. The significant difference for PAI-1, SP, and SP-R between the nano-Cu/LDPE groups and the SO group (P<0.05) was identified when the observation period was terminated, and the changes of nano-Cu/LDPE on these parameters were less remarkable than those of the Cu group (P<0.05). The damage to the endometrial morphology caused by the nano-Cu/LDPE composite was much less than that caused by bulk copper. The nano-Cu/LDPE composite might be a potential substitute for conventional materials for intrauterine devices in the future because of its decreased adverse effects on the endometrial microenvironment.

Undercooling and solidification behavior in the InSb-Sb system. M.S. Thesis. Final Report

NASA Technical Reports Server (NTRS)

Graves, J. A.

1985-01-01

Use of the droplet emulsion technique has been successful in studying the undercooling and crystallization behavior of Sb, InSb, and an InSb-Sb eutectic alloy. Both droplet size and imposed cooling rate were influential in controlling the extent of liquid undercooling. The droplet surface coating was of significant importance in determining the resultant solidification product structure through its effect on nucleation kinetics. The maximum undercooling for pure Sb was extended from 0.08 to 0.23 T sub m. While simple crushing techniques provided a dramatic increase in droplet undercooling over the bulk material, emulsification treatments both enhanced this undercooling and allowed successful formation of a metastable simple cubic Sb phase. This phase was stable to temperatures approaching the melting point. The simple cubic phase was detected in droplet samples processed using DTA, air and water quenching, and drop tube processing under a helium gas atmosphere. A deviation in the InSb parent ingot composition limited interpretation of the line compound results, however, emulsification techniques extended the undercooling of this material to 0.17 T sub L and provided a stable, protective surface coating for the droplets. Emulsification of the eutectic alloy was effective at producing various levels of undercooling from 0.1 to 0.2 T sub E. Microstructural examination revealed a normal-type eutectic structure in the undercooled droplets indicating that solidification occurred within the coupled zone and that this zone is somewhat symmetric about the eutectic composition.

"Micro to macro (M2M)"--A novel approach for intravenous delivery of propofol.

PubMed

Damitz, Robert; Chauhan, Anuj

2015-10-15

Propofol emulsions have limited shelf life and safety concerns for injection. Microemulsions of propofol are thermodynamically stable and simpler to manufacture, but cause additional pain on injection. We propose a novel micro to macro (M2M) approach of destabilizing a microemulsion immediately prior to injection. Microemulsions of propofol were prepared at two to three times the drug loadings of commercial formulations. We determined suitable microemulsion compositions which destabilize into macroemulsions after two or three fold dilutions with water. Droplet growth after dilution was measured with dynamic light scattering. Increasing solution turbidity after dilution was also measured optically with millisecond resolution. Experimental data was analyzed in the context of a coalescence model. Microemulsions rapidly coalesce into larger droplet size macroemulsions after dilution according to the phase diagram shift. The resulting macroemulsions are metastable retaining their droplet size for several hours. Droplet growth occurs on the order of seconds and a metastable size of about 1 micron is reached in minutes. Rates of droplet growth and metastable droplet sizes depend on the surfactant composition. The coalescence model predicts droplet growth with good agreement but only after accounting for the finite probability of coalescence from each collision. The M2M concept has been demonstrated for the anesthetic drug propofol which may improve stability and manufacturability in addition to reducing pain on injection. This approach could be adapted to other hydrophobic vesicant drugs as well. Copyright © 2015 Elsevier B.V. All rights reserved.

Evolutionarily conserved gene family important for fat storage

PubMed Central

Kadereit, Bert; Kumar, Pradeep; Wang, Wen-Jun; Miranda, Diego; Snapp, Erik L.; Severina, Nadia; Torregroza, Ingrid; Evans, Todd; Silver, David L.

2008-01-01

The ability to store fat in the form of cytoplasmic triglyceride droplets is conserved from Saccharomyces cerevisiae to humans. Although much is known regarding the composition and catabolism of lipid droplets, the molecular components necessary for the biogenesis of lipid droplets have remained obscure. Here we report the characterization of a conserved gene family important for lipid droplet formation named fat-inducing transcript (FIT). FIT1 and FIT2 are endoplasmic reticulum resident membrane proteins that induce lipid droplet accumulation in cell culture and when expressed in mouse liver. shRNA silencing of FIT2 in 3T3-LI adipocytes prevents accumulation of lipid droplets, and depletion of FIT2 in zebrafish blocks diet-induced accumulation of lipid droplets in the intestine and liver, highlighting an important role for FIT2 in lipid droplet formation in vivo. Together these studies identify and characterize a conserved gene family that is important in the fundamental process of storing fat. PMID:18160536

Study of rheological, viscoelastic and vulcanization behavior of sponge EPDM/NR blended nano- composites

NASA Astrophysics Data System (ADS)

Arshad Bashir, M.; Shahid, M.; Ahmed, Riaz; Yahya, A. G.

2014-06-01

In this research paper the effect of blending ratio of natural rubber (NR) with Ethylene Propylene Diene Monomer (EPDM) were investigated. Different samples of EPDM/NR ratio were prepared to study the variation of NR in EPDM on rheology, curing characteristics, tangent δ, and viscosity variation during vulcanization of sponge nano composites.The main aim of present research is to develop elastomeric based sponge composites with the blending ratio of base elastomers along with the carbon nano particles for high energy absorbing and damping applications. The curing characteristics, rheology and viscoelastic nature of the composite is remarkably influenced with the progressive blending ratio of the base elastomeric matrix.

Technologies That Enable Accurate and Precise Nano- to Milliliter-Scale Liquid Dispensing of Aqueous Reagents Using Acoustic Droplet Ejection.

PubMed

Sackmann, Eric K; Majlof, Lars; Hahn-Windgassen, Annett; Eaton, Brent; Bandzava, Temo; Daulton, Jay; Vandenbroucke, Arne; Mock, Matthew; Stearns, Richard G; Hinkson, Stephen; Datwani, Sammy S

2016-02-01

Acoustic liquid handling uses high-frequency acoustic signals that are focused on the surface of a fluid to eject droplets with high accuracy and precision for various life science applications. Here we present a multiwell source plate, the Echo Qualified Reservoir (ER), which can acoustically transfer over 2.5 mL of fluid per well in 25-nL increments using an Echo 525 liquid handler. We demonstrate two Labcyte technologies-Dynamic Fluid Analysis (DFA) methods and a high-voltage (HV) grid-that are required to maintain accurate and precise fluid transfers from the ER at this volume scale. DFA methods were employed to dynamically assess the energy requirements of the fluid and adjust the acoustic ejection parameters to maintain a constant velocity droplet. Furthermore, we demonstrate that the HV grid enhances droplet velocity and coalescence at the destination plate. These technologies enabled 5-µL per destination well transfers to a 384-well plate, with accuracy and precision values better than 4%. Last, we used the ER and Echo 525 liquid handler to perform a quantitative polymerase chain reaction (qPCR) assay to demonstrate an application that benefits from the flexibility and larger volume capabilities of the ER. © 2015 Society for Laboratory Automation and Screening.

Evaluation of Shear Bond Strength of Orthodontic Brackets Bonded with Nano-Filled Composites

PubMed Central

Chalipa, Javad; Akhondi, Mohammad Sadegh Ahmad; Arab, Sepideh; Kharrazifard, Mohammad Javad; Ahmadyar, Maryam

2013-01-01

Objectives: The purpose of this study was to evaluate the shear bond strength (SBS) of orthodontic brackets bonded with two types of nano-composites in comparison to a conventional orthodontic composite. Materials and Methods: Sixty extracted human first premolars were randomly divided into 3 groups each containing 20 teeth. In group I, a conventional orthodontic composite (Transbond XT) was used to bond the brackets, while two nano-composites (Filtek TM Supreme XT and AELITE Aesthetic Enamel) were used in groups II and III respectively. The teeth were stored in distilled water at 37°C for 24 hours, thermocycled in distilled water and debonded with a universal testing machine at a crosshead speed of 1 mm/min. The adhesive remnant index (ARI) was also evaluated using a stereomicroscope. Results: AELITE Aesthetic Enamel nano-composite revealed a SBS value of 8.44±2.09 MPa, which was higher than Transbond XT (6.91±2.13) and Filtek TM Supreme XT (6.04±2.01). Statistical analysis revealed a significant difference between groups II and III (P < 0.05). No significant difference was found between groups I and III, and between groups I and II (P > 0.05). Evaluation of ARI showed that Transbond XT left fewer adhesive remains on teeth after debonding. Conclusion: Results of this study indicate that the aforementioned nano-composites can be successfully used for bonding orthodontic brackets. PMID:24910655

Effect of mechanical properties of fillers on the grindability of composite resin adhesives.

PubMed

Iijima, Masahiro; Muguruma, Takeshi; Brantley, William A; Yuasa, Toshihiro; Uechi, Jun; Mizoguchi, Itaru

2010-10-01

The purpose of this study was to investigate the effect of filler properties on the grindability of composite resin adhesives. Six composite resin products were selected: Transbond XT (3M Unitek, Monrovia, Calif), Transbond Plus (3M Unitek), Enlight (Ormco, Glendora, Calif), Kurasper F (Kuraray Medical, Tokyo, Japan), Beauty Ortho Bond (Shofu, Kyoto, Japan), and Beauty Ortho Bond Salivatect (Shofu). Compositions and weight fractions of fillers were determined by x-ray fluorescence analysis and ash test, respectively. The polished surface of each resin specimen was examined with a scanning electron microscope. Vickers hardness of plate specimens (15 × 10 × 3 mm) was measured, and nano-indentation was performed on large filler particles (>10 μm). Grindability for a low-speed tungsten-carbide bur was estimated. Data were compared with anlaysis of variance (ANOVA) and the Tukey multiple range test. Relationships among grindability, filler content, filler nano-indentation hardness (nano-hardness), filler elastic modulus, and Vickers hardness of the composite resins were investigated with the Pearson correlation coefficient test. Morphology and filler size of these adhesives showed great variations. The products could be divided into 2 groups, based on composition, which affected grindability. Vickers hardness of the adhesives did not correlate (r = 0.140) with filler nano-hardness, which showed a significant negative correlation (r = -0.664) with grindability. Filler nano-hardness greatly influences the grindability of composite resin adhesives. Copyright © 2010 American Association of Orthodontists. Published by Mosby, Inc. All rights reserved.

Nitrate removal by Fe0/Pd/Cu nano-composite in groundwater.

PubMed

Liu, Hongyuan; Guo, Min; Zhang, Yan

2014-01-01

Nitrate pollution in groundwater shows a great threat to the safety of drinking water. Chemical reduction by zero-valent iron is being considered as a promising technique for nitrate removal from contaminated groundwater. In this paper, Fe0/Pd/Cu nano-composites were prepared by the liquid-phase reduction method, and batch experiments of nitrate reduction by the prepared Fe0/Pd/Cu nano-composites under various operating conditions were carried out. It has been found that nano-Fe0/Pd/Cu composites processed dual functions: catalytic reduction and chemical reduction. The introduction of Pd and Cu not only improved nitrate removal rate, but also reduced the generation of ammonia. Nitrate removal rate was affected by the amount of Fe0/Pd/Cu, initial nitrate concentration, solution pH, dissolved oxygen (DO), reaction temperature, the presence of anions, and organic pollutant. Moreover, nitrate reduction by Fe0/Pd/Cu composites followed the pseudo-first-order reaction kinetics. The removal rate of nitrate and total nitrogen were about 85% and 40.8%, respectively, under the reaction condition of Fe-6.0%Pd-3.0%Cu amount of 0.25 g/L, pH value of 7.1, DO of 0.42 mg/L, and initial nitrate concentration of 100 mg/L. Compared with the previous studies with Fe0 alone or Fe-Cu, nano-Fe-6%Pd-3%Cu composites showed a better selectivity to N2.

Nano-fabricated superconducting radio-frequency composites, method for producing nano-fabricated superconducting rf composites

DOEpatents

Norem, James H.; Pellin, Michael J.

2013-06-11

Superconducting rf is limited by a wide range of failure mechanisms inherent in the typical manufacture methods. This invention provides a method for fabricating superconducting rf structures comprising coating the structures with single atomic-layer thick films of alternating chemical composition. Also provided is a cavity defining the invented laminate structure.

Contrasting Cloud Composition Between Coupled and Decoupled Marine Boundary Layer Clouds

NASA Astrophysics Data System (ADS)

WANG, Z.; Mora, M.; Dadashazar, H.; MacDonald, A.; Crosbie, E.; Bates, K. H.; Coggon, M. M.; Craven, J. S.; Xian, P.; Campbell, J. R.; AzadiAghdam, M.; Woods, R. K.; Jonsson, H.; Flagan, R. C.; Seinfeld, J.; Sorooshian, A.

2016-12-01

Marine stratocumulus clouds often become decoupled from the vertical layer immediately above the ocean surface. This study contrasts cloud chemical composition between coupled and decoupled marine stratocumulus clouds. Cloud water and droplet residual particle composition were measured in clouds off the California coast during three airborne experiments in July-August of separate years (E-PEACE 2011, NiCE 2013, BOAS 2015). Decoupled clouds exhibited significantly lower overall mass concentrations in both cloud water and droplet residual particles, consistent with reduced cloud droplet number concentration and sub-cloud aerosol (Dp > 100 nm) number concentration, owing to detachment from surface sources. Non-refractory sub-micrometer aerosol measurements show that coupled clouds exhibit higher sulfate mass fractions in droplet residual particles, owing to more abundant precursor emissions from the ocean and ships. Consequently, decoupled clouds exhibited higher mass fractions of organics, nitrate, and ammonium in droplet residual particles, owing to effects of long-range transport from more distant sources. Total cloud water mass concentration in coupled clouds was dominated by sodium and chloride, and their mass fractions and concentrations exceeded those in decoupled clouds. Conversely, with the exception of sea salt constituents (e.g., Cl, Na, Mg, K), cloud water mass fractions of all species examined were higher in decoupled clouds relative to coupled clouds. These results suggest that an important variable is the extent to which clouds are coupled to the surface layer when interpreting microphysical data relevant to clouds and aerosol particles.

Achieving Higher Strength and Sensitivity toward UV Light in Multifunctional Composites by Controlling the Thickness of Nano-Layer on the Surface of Glass Fiber.

PubMed

Sun, Chao; Zhang, Jie; Gao, Shanglin; Zhang, Nan; Zhang, Yijun; Zhuang, Jian; Liu, Ming; Zhang, Xiaohui; Ren, Wei; Wu, Hua; Ye, Zuo-Guang

2018-06-18

The interphase between fiber and matrix plays an essential role in the performance of composites. Therefore, the ability to design or modify the interphase is a key technology needed to manufacture stronger and smarter composite. Recently, depositing nano-materials onto the surface of the fiber has become a promising approach to optimize the interphase and composites. But, the modified composites have not reached the highest strength yet, because the determining parameters, such as thickness of the nano-layer, are hardly controlled by the mentioned methods in reported works. Here, we deposit conformal ZnO nano-layer with various thicknesses onto the surfaces of glass fibers via the atomic layer deposition (ALD) method and a tremendous enhancement of interfacial shear strength of composites is achieved. Importantly, a critical thickness of ZnO nano-layer is obtained for the first time, giving rise to a maximal relative enhancement in the interfacial strength, which is more than 200% of the control fiber. In addition, the single modified fiber exhibits a potential application as a flexible, transparent, in-situ UV detector in composites. And, we find the UV-sensitivity also shows a strong correlation with the thickness of ZnO. To reveal the dependence of UV-sensitivity on thickness, a depletion thickness is estimated by a proposed model which is an essential guide to design the detectors with higher sensitivity. Consequently, such precise tailoring of the interphase offers an advanced way to improve and to flexibly control various macroscopic properties of multifunctional composites of the next generation.

The free radical chemistry of cloud droplets and its impact upon the composition of rain

NASA Technical Reports Server (NTRS)

Chameides, W. L.; Davis, D. D.

1982-01-01

Calculations are presented that simulate the free radical chemistries of the gas phase and aqueous phase within a warm cloud during midday. It is demonstrated that in the presence of midday solar fluxes, the heterogeneous scavenging of OH and HO2 from the gas phase by cloud droplets can represent a major source of free radicals to cloud water, provided the accommodation or sticking coefficient for these species impinging upon water droplets is not less than 0.0001. The aqueous-phase of HO2 radicals are found to be converted to H2O2 by aqueous-phase chemical reactions at a rate that suggests that this mechanism could produce a significant fraction of the H2O2 found in cloud droplets. The rapid oxidation of sulfur species dissolved in cloudwater by this free-radical-produced H2O2 as well as by aqueous-phase OH radicals could conceivably have a significant impact upon the chemical composition of rain.

Effect of Calcium Sulphate Nanoparticles on Fusion, Mechanical and Thermal Behaviour Polyvinyl Chloride (pvc)

NASA Astrophysics Data System (ADS)

Patil, C. B.; Shisode, P. S.; Kapadi, U. R.; Hundiwale, D. G.; Mahulikar, P. P.

Calcium Sulphate [CaSO4] was synthesized by in-situ deposition technique and its nano size (60 to 100 nm) was confirmed by Transmission Electron Microscopy (TEM). Composites of the filler CaSO4 (micro and nano) and the matrix poly (vinyl chloride) (PVC) were prepared with different filler loading (0-5 wt. %) by melt mixing. The Brabender torque rheometer equipped with an internal mixer was used for preparation and evaluation of fusion behaviour of composites of different formulations. The effect of nano and micro-CaSO4 content on the structure and properties of composites was studied. The nanostructures and dispersion were studied by wide angle X-ray diffraction (WAXD) and scanning electron microscopy (SEM). The mechanical and thermal properties of PVC/ micro and nano-CaSO4 composites were characterized using Universal Testing Machine (UTM) and Thermo Gravimetric Analyzer (TGA). From the results of WAXD and SEM the flocculation of CaSO4 nanoparticles were observed on the surfaces of PVC matrix. The thermal analysis results showed that the first thermal degradation onset (T onset) of PVC/nano-CaSO4 composites for 1 wt. % of filler were higher as compared with corresponding microcomposites and pristine PVC. However, the tensile strength was decreasing with increasing filler content while, it shows increment in magnitude at 1 and 2 wt. % of nano-CaSO4 as compared with corresponding micro-CaSO4 as well as pristine PVC.

In Vitro Cytotoxicity Assessment of an Orthodontic Composite Containing Titanium-dioxide Nano-particles.

PubMed

Heravi, Farzin; Ramezani, Mohammad; Poosti, Maryam; Hosseini, Mohsen; Shajiei, Arezoo; Ahrari, Farzaneh

2013-01-01

Background and aims. Incorporation of nano-particles to orthodontic bonding systems has been considered to prevent enamel demineralization around appliances. This study investigated cytotoxicity of Transbond XT adhesive containing 1 wt% titanium dioxide (TiO2) nano-particles. Materials and methods. Ten composite disks were prepared from each of the conventional and TiO2-containg composites and aged for 1, 3, 5, 7 and 14 days in Dulbecco's Modified Eagle's Medium (DMEM). The extracts were obtained and exposed to culture media of human gingival fibroblasts (HGF) and mouse L929 fibroblasts. Cell viability was measured using the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay. Results. Both adhesives were moderately toxic for HGF cells on the first day of the experiment, but the TiO2-containing adhesive produced significantly lower toxicity than the pure adhesive (P<0.05). No significant differences were found in cell viability percentages between the two groups on the other days (P>0.05). There was a significant reduction in cell toxicity with increasing pre-incubation time (P<0.001). L929 cells showed similar toxicity trends, but lower sensitivity to detect cytotoxicity of dental composites. Conclusion. The orthodontic adhesive containing TiO2 nano-particles indicated comparable or even lower toxicity than its nano-particle-free counterpart, indicating that incorporation of 1 wt% TiO2 nano-particles to the composite structure does not result in additional health hazards compared to that occurring with the pure adhesive.

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

PubMed

Benea, Lidia; Celis, Jean-Pierre

2016-04-06

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

Effects of ultrasonic vibration on microstructure and mechanical properties of nano-sized SiC particles reinforced Al-5Cu composites.

PubMed

Li, Jianyu; Lü, Shulin; Wu, Shusen; Gao, Qi

2018-04-01

Ultrasonic vibration (UV) treatment has been successfully applied to improve the particles distribution of nano-sized SiC particles (SiC p ) reinforced Al-5Cu alloy matrix composites which were prepared by combined processes of dry high energy ball milling and squeeze casting. When UV treatment is applied, the distribution of nano-sized SiC p has been greatly improved. After UV for 1 min, large particles aggregates are broken up into small aggregates due to effects of cavitation and the acoustic streaming. After UV for 5 min, all the particles aggregates are dispersed and the particles are uniformly distributed in the composites. Compared with the Al-5Cu matrix alloy, the ultimate tensile strength, yield strength and elongation of the 1 wt% nano-sized SiC p /Al-5Cu composites treated by UV for 5 min are 270 MPa, 173 MPa and 13.3%, which are increased by 7.6%, 6.8% and 29%, respectively. The improvements of mechanical properties after UV are attributed to the uniform distribution of nano particles, grain refinement of aluminum matrix alloy and reduction of porosity in the composites. Copyright © 2017 Elsevier B.V. All rights reserved.

Substrate stiffness influences high resolution printing of living cells with an ink-jet system.

PubMed

Tirella, Annalisa; Vozzi, Federico; De Maria, Carmelo; Vozzi, Giovanni; Sandri, Tazio; Sassano, Duccio; Cognolato, Livio; Ahluwalia, Arti

2011-07-01

The adaptation of inkjet printing technology for the realisation of controlled micro- and nano-scaled biological structures is of great potential in tissue and biomaterial engineering. In this paper we present the Olivetti BioJet system and its applications in tissue engineering and cell printing. BioJet, which employs a thermal inkjet cartridge, was used to print biomolecules and living cells. It is well known that high stresses and forces are developed during the inkjet printing process. When printing living particles (i.e., cell suspensions) the mechanical loading profile can dramatically damage the processed cells. Therefore computational models were developed to predict the velocity profile and the mechanical load acting on a droplet during the printing process. The model was used to investigate the role of the stiffness of the deposition substrate during droplet impact and compared with experimental investigations on cell viability after printing on different materials. The computational model and the experimental results confirm that impact forces are highly dependent on the deposition substrate and that soft and viscous surfaces can reduce the forces acting on the droplet, preventing cell damage. These results have high relevance for cell bioprinting; substrates should be designed to have a good compromise between substrate stiffness to conserve spatial patterning without droplet coalescence but soft enough to absorb the kinetic energy of droplets in order to maintain cell viability. Copyright © 2011. Published by Elsevier B.V.

Fuel Droplet Burning During Droplet Combustion Experiment

NASA Technical Reports Server (NTRS)

2003-01-01

Fuel ignites and burns in the Droplet Combustion Experiment (DCE) on STS-94 on July 4 1997, MET:2/05:40 (approximate). The DCE was designed to investigate the fundamental combustion aspects of single, isolated droplets under different pressures and ambient oxygen concentrations for a range of droplet sizes varying between 2 and 5 mm. DCE used various fuels -- in drops ranging from 1 mm (0.04 inches) to 5 mm (0.2 inches) -- and mixtures of oxidizers and inert gases to learn more about the physics of combustion in the simplest burning configuration, a sphere. The experiment elapsed time is shown at the bottom of the composite image. The DCE principal investigator was Forman Williams, University of California, San Diego. The experiment was part of the space research investigations conducted during the Microgravity Science Laboratory-1R mission (STS-94, July 1-17 1997). Advanced combustion experiments will be a part of investigations plarned for the International Space Station. (1.4MB, 13-second MPEG, screen 320 x 240 pixels; downlinked video, higher quality not available)A still JPG composite of this movie is available at http://mix.msfc.nasa.gov/ABSTRACTS/MSFC-0300168.html.

The role of lipid droplets and adipocytes in cancer. Raman imaging of cell cultures: MCF10A, MCF7, and MDA-MB-231 compared to adipocytes in cancerous human breast tissue.

PubMed

Abramczyk, Halina; Surmacki, Jakub; Kopeć, Monika; Olejnik, Alicja Klaudia; Lubecka-Pietruszewska, Katarzyna; Fabianowska-Majewska, Krystyna

2015-04-07

We have studied live non-malignant (MCF10A), mildly malignant (MCF7) and malignant (MDA-MB-231) breast cancer cells and human breast cancer tissue. We demonstrate the first application of Raman imaging and spectroscopy in diagnosing the role of lipid droplets in cell line cultures that closely mimic an in vivo environment of various stages in human breast cancer tissue. We have analyzed the composition of the lipid droplets in non-malignant and malignant human breast epithelial cell lines and discussed the potential of lipid droplets as a prognostic marker in breast cancer. To identify any difference in the lipid droplet-associated biochemistry and to correlate it with different stages of breast cancer, the PCA method was employed. The chemical composition of lipids and proteins, both in the cell line models and in human breast tissue has been analyzed. The paper shows the alterations in lipid metabolism that have been reported in cancer, at both the cellular and tissue levels, and discusses how they contribute to the different aspects of tumourigenesis.

Controlled Gelation of Particle Suspensions Using Controlled Solvent Removal in Picoliter Droplets

NASA Astrophysics Data System (ADS)

Vuong, Sharon; Walker, Lynn; Anna, Shelley

2013-11-01

Droplets in microfluidic devices have proven useful as uniform picoliter reactors for nanoparticle synthesis and as components in tunable emulsions. However, there can be significant transport between the component phases depending on solubility and other factors. In the present talk, we show that water droplets trapped within a microfluidic device for tens of hours slowly dehydrate, concentrating the contents encapsulated within. We use this slow dehydration along with control of the initial droplet composition to monitor gelation of aqueous suspensions of spherical silica particles (Ludox) and disk-shaped clay particles (Laponite). Droplets are generated in a microfluidic device containing small wells that trap the droplets. We monitor the concentration process through size and shape changes of these droplets as a function of time in tens of droplets and use the large number of individual reactors to generate statistics regarding the gelation process. We also examine changes in suspension viscosity through fluorescent particle tracking as a function of dehydration rate, initial suspension concentration and initial droplet volume, and added salt, and compare the results with the Krieger-Dougherty model in which viscosity increases dramatically with particle volume fraction.

Income Inequality, Race, and Child Well-Being: An Aggregate Analysis in the 50 United States

ERIC Educational Resources Information Center

McLeod, Jane D.; Nonnemaker, James M.; Call, Kathleen Thiede

2004-01-01

Interest in income inequality as a predictor of health has exploded since the mid-1990s. Recent analyses suggest, however, that the effect of income inequality on population health is not robust to a control for the racial composition of the population. That observation raises two interpretational questions. First, does income inequality have an…

Oxygen Isotope Composition of Almahata Sitta

NASA Technical Reports Server (NTRS)

Rumble, D.; Zolensky, M. E.; Friedrich, J. M.; Jenniskens, P.; Shaddad, M. H.

2010-01-01

The name Almahata Sitta is applied collectively to some hundreds of stones that were found in a linear strewn field in the Nubian Desert coincident with the projected Earth-impacting orbit of the Asteroid 2008 TC3. Fragments of the meteorite were collected in December 2008 and March 2009, 2 to 5 months after the asteroid exploded in Earths atmosphere on 7 October 2008.

Dispersion of iron nano-particles on expanded graphite for the shielding of electromagnetic radiation

NASA Astrophysics Data System (ADS)

Xu, Zheng; Huang, Yu'an; Yang, Yang; Shen, Jianyi; Tang, Tao; Huang, Runsheng

2010-10-01

Composite materials containing electrically conductive expanded graphite (EG) and magnetic iron nano-particles for electromagnetic shielding were prepared by impregnating EG with an ethanol solution containing iron nitrate and acetic acid, followed by drying and reduction in H 2. Magnetic nano-iron particles were found to be highly dispersed on the surface of EG in the Fe/EG composites, and played the role of enhancing the electromagnetic shielding effectiveness (SE) at low frequencies (0.3-10 MHz), which seemed to depend proportionally on magnetic hysteresis loss of loaded iron nano-particles.

Design and fabrication of highly hydrophobic Mn nano-sculptured thin films and evaluation of surface properties on hydrophobicity

NASA Astrophysics Data System (ADS)

Hosseini, Somaye; Savaloni, Hadi; Gholipour-Shahraki, Mehran

2017-03-01

The wettability of solid surfaces is important from the aspects of both science and technology. The Mn nano-sculptured thin films were designed and fabricated by oblique angle deposition of Mn on glass substrates at room temperature. The obtained structure was characterized by field emission scanning electron microscopy and atomic force microscopy. The wettability of thin films samples was investigated by water contact angle (WCA). The 4-pointed helical star-shaped structure exhibits hydrophobicity with static WCAs of more than 133° for a 10-mg distilled water droplet. This sample also shows the rose petal effect with the additional property of high adhesion. The Mn nano-sculptured thin films also act as a sticky surface which is confirmed by hysteresis of the contact angle obtained from advancing and receding contact angles measurements. Physicochemical property of liquid phase could effectively change the contact angle, and polar solvents in contact with hydrophobic solid surfaces do not necessarily show high contact angle value.

Bead-on-string structure printed by electrohydrodynamic jet under alternating current electric field

NASA Astrophysics Data System (ADS)

Liu, Juan; Lin, Yihuang; Jiang, Jiaxin; Liu, Haiyan; Zhao, Yang; Zheng, Gaofeng

2016-09-01

Electrohydrodynamic printing (EHDP) under alternating current (AC) electric field provides a novel way for the precise micro-/nano-droplet printing. The AC electric field induces the free charge to reciprocate along the EHDP jet and changes the electric field force on the jet periodically. The stability of jet can be enhanced by increasing the voltage frequency, and the regular bead-on-string structure is direct-written along the trajectory of collector. The deposition frequency of bead structure increases with the increasing of voltage frequency, due to the short period of AC electric field. As the voltage frequency is increased from 10 to 60 Hz, the diameter of bead structure decreases from 200 to 110 µm. As the duty ration increased from 10 to 60 %, the diameter of bead structure increased from 100 to 140 µm. This work would accelerate the development and the application of micro-/nano-printing technology in the fields of flexible electronic and micro-/nano-system.

The effect of acid–base clustering and ions on the growth of atmospheric nano-particles

DOE PAGES

Lehtipalo, Katrianne; Rondo, Linda; Kontkanen, Jenni; ...

2016-05-20

The growth of freshly formed aerosol particles can be the bottleneck in their survival to cloud condensation nuclei. It is therefore crucial to understand how particles grow in the atmosphere. Insufficient experimental data has impeded a profound understanding of nano-particle growth under atmospheric conditions. Here we study nano-particle growth in the CLOUD (Cosmics Leaving OUtdoors Droplets) chamber, starting from the formation of molecular clusters. We present measured growth rates at sub-3 nm sizes with different atmospherically relevant concentrations of sulphuric acid, water, ammonia and dimethylamine. We find that atmospheric ions and small acid-base clusters, which are not generally accounted formore » in the measurement of sulphuric acid vapour, can participate in the growth process, leading to enhanced growth rates. The availability of compounds capable of stabilizing sulphuric acid clusters governs the magnitude of these effects and thus the exact growth mechanism. Furthermore, we bring these observations into a coherent framework and discuss their significance in the atmosphere.« less

The effect of acid–base clustering and ions on the growth of atmospheric nano-particles

PubMed Central

Lehtipalo, Katrianne; Rondo, Linda; Kontkanen, Jenni; Schobesberger, Siegfried; Jokinen, Tuija; Sarnela, Nina; Kürten, Andreas; Ehrhart, Sebastian; Franchin, Alessandro; Nieminen, Tuomo; Riccobono, Francesco; Sipilä, Mikko; Yli-Juuti, Taina; Duplissy, Jonathan; Adamov, Alexey; Ahlm, Lars; Almeida, João; Amorim, Antonio; Bianchi, Federico; Breitenlechner, Martin; Dommen, Josef; Downard, Andrew J.; Dunne, Eimear M.; Flagan, Richard C.; Guida, Roberto; Hakala, Jani; Hansel, Armin; Jud, Werner; Kangasluoma, Juha; Kerminen, Veli-Matti; Keskinen, Helmi; Kim, Jaeseok; Kirkby, Jasper; Kupc, Agnieszka; Kupiainen-Määttä, Oona; Laaksonen, Ari; Lawler, Michael J.; Leiminger, Markus; Mathot, Serge; Olenius, Tinja; Ortega, Ismael K.; Onnela, Antti; Petäjä, Tuukka; Praplan, Arnaud; Rissanen, Matti P.; Ruuskanen, Taina; Santos, Filipe D.; Schallhart, Simon; Schnitzhofer, Ralf; Simon, Mario; Smith, James N.; Tröstl, Jasmin; Tsagkogeorgas, Georgios; Tomé, António; Vaattovaara, Petri; Vehkamäki, Hanna; Vrtala, Aron E.; Wagner, Paul E.; Williamson, Christina; Wimmer, Daniela; Winkler, Paul M.; Virtanen, Annele; Donahue, Neil M.; Carslaw, Kenneth S.; Baltensperger, Urs; Riipinen, Ilona; Curtius, Joachim; Worsnop, Douglas R.; Kulmala, Markku

2016-01-01

The growth of freshly formed aerosol particles can be the bottleneck in their survival to cloud condensation nuclei. It is therefore crucial to understand how particles grow in the atmosphere. Insufficient experimental data has impeded a profound understanding of nano-particle growth under atmospheric conditions. Here we study nano-particle growth in the CLOUD (Cosmics Leaving OUtdoors Droplets) chamber, starting from the formation of molecular clusters. We present measured growth rates at sub-3 nm sizes with different atmospherically relevant concentrations of sulphuric acid, water, ammonia and dimethylamine. We find that atmospheric ions and small acid-base clusters, which are not generally accounted for in the measurement of sulphuric acid vapour, can participate in the growth process, leading to enhanced growth rates. The availability of compounds capable of stabilizing sulphuric acid clusters governs the magnitude of these effects and thus the exact growth mechanism. We bring these observations into a coherent framework and discuss their significance in the atmosphere. PMID:27197574

Printing of highly conductive solution by alternating current electrohydrodynamic direct-write

NASA Astrophysics Data System (ADS)

Jiang, Jiaxin; Zheng, Gaofeng; Wang, Xiang; Zheng, Jianyi; Liu, Juan; Liu, Yifang; Li, Wenwang; Guo, Shumin

2018-03-01

Electrohydrodynamic Direct-Write (EDW) is a novel technology for the printing of micro/nano structures. In this paper, Alternating Current (AC) electrical field was introduced to improve the ejection stability of jet with highly conductive solution. By alternating the electrical field, the polarity of free charges on the surface of jet was changed and the average density of charge, as well as the repulsive force, was reduced to stabilize the jet. When the frequency of AC electrical field increased, the EDW process became more stable and the shape of deposited droplets became more regular. The diameter of printed droplets decreased and the deposition frequency increased with the increase of voltage frequency. The phenomenon of corona discharge was overcome effectively as well. To further evaluate the performance of AC EDW for highly conductive solution, more NaCl was added to the solution and the conductivity was increased to 2810μs/cm. With such high conductivity, the problem of serious corona discharge could still be prevented by AC EDW, and the diameter of printed droplets decreased significantly. This work provides an effective way to accelerate industrial applications of EDW.

Monodisperse Polyethylene Glycol Diacrylate Hydrogel Microsphere Formation by Oxygen-Controlled Photopolymerization in a Microfluidic Device

PubMed Central

Krutkramelis, K.; Xia, B.; Oakey, J.

2016-01-01

PEG-based hydrogels have become widely used as drug delivery and tissue scaffolding materials. Common among PEG hydrogel-forming polymers are photopolymerizable acrylates such as polyethylene glycol diacrylate (PEGDA). Microfluidics and microfabrication technologies have recently enabled the miniaturization of PEGDA structures, thus enabling many possible applications for nano- and micro- structured hydrogels. The presence of oxygen, however, dramatically inhibits the photopolymerization of PEGDA, which in turn frustrates hydrogel formation in environments of persistently high oxygen concentration. Using PEGDA that has been emulsified in fluorocarbon oil via microfluidic flow focusing within polydimethylsiloxane (PDMS) devices, we show that polymerization is completely inhibited below critical droplet diameters. By developing an integrated model incorporating reaction kinetics and oxygen diffusion, we demonstrate that the critical droplet diameter is largely determined by the oxygen transport rate, which is dictated by the oxygen saturation concentration of the continuous oil phase. To overcome this fundamental limitation, we present a nitrogen micro-jacketed microfluidic device to reduce oxygen within the droplet, enabling the continuous on-chip photopolymerization of microscale PEGDA particles. PMID:26987384

Method for gas-metal arc deposition

DOEpatents

Buhrmaster, C.L.; Clark, D.E.; Smartt, H.B.

1990-11-13

Method and apparatus for gas-metal arc deposition of metal, metal alloys, and metal matrix composites are disclosed. The apparatus contains an arc chamber for confining a D.C. electrical arc discharge, the arc chamber containing an outlet orifice in fluid communication with a deposition chamber having a deposition opening in alignment with the orifice for depositing metal droplets on a coatable substrate. Metal wire is passed continuously into the arc chamber in alignment with the orifice. Electric arcing between the metal wire anode and the orifice cathode produces droplets of molten metal from the wire which pass through the orifice and into the deposition chamber for coating a substrate exposed at the deposition opening. When producing metal matrix composites, a suspension of particulates in an inert gas enters the deposition chamber via a plurality of feed openings below and around the orifice so that reinforcing particulates join the metal droplets to produce a uniform mixture which then coats the exposed substrate with a uniform metal matrix composite. 1 fig.

Method for gas-metal arc deposition

DOEpatents

Buhrmaster, Carol L.; Clark, Denis E.; Smartt, Herschel B.

1990-01-01

Method and apparatus for gas-metal arc deposition of metal, metal alloys, and metal matrix composites. The apparatus contains an arc chamber for confining a D.C. electrical arc discharge, the arc chamber containing an outlet orifice in fluid communication with a deposition chamber having a deposition opening in alignment wiht the orifice for depositing metal droplets on a coatable substrate. Metal wire is passed continuously into the arc chamber in alignment with the orifice. Electric arcing between the metal wire anode and the orifice cathode produces droplets of molten metal from the wire which pass through the orifice and into the deposition chamber for coating a substrate exposed at the deposition opening. When producing metal matrix composites, a suspension of particulates in an inert gas enters the deposition chamber via a plurality of feed openings below and around the orifice so that reinforcing particulates join the metal droplets to produce a uniform mixture which then coats the exposed substrate with a uniform metal matrix composite.

Apparatus for gas-metal arc deposition

DOEpatents

Buhrmaster, Carol L.; Clark, Denis E.; Smartt, Herschel B.

1991-01-01

Apparatus for gas-metal arc deposition of metal, metal alloys, and metal matrix composites. The apparatus contains an arc chamber for confining a D.C. electrical arc discharge, the arc chamber containing an outlet orifice in fluid communication with a deposition chamber having a deposition opening in alignment with the orifice for depositing metal droplets on a coatable substrate. Metal wire is passed continuously into the arc chamber in alignment with the orifice. Electric arcing between the metal wire anode and the orifice cathode produces droplets of molten metal from the wire which pass through the orifice and into the deposition chamber for coating a substrate exposed at the deposition opening. When producing metal matrix composites, a suspenion of particulates in an inert gas enters the deposition chamber via a plurality of feed openings below and around the orifice so that reinforcing particulates join the metal droplets to produce a uniform mixture which then coats the exposed substrate with a uniform metal matrix composite.

Preparation and Investigation of Electrodeposited Ni-NANO-Cr2O3 Composite Coatings

NASA Astrophysics Data System (ADS)

Jiang, Jibo; Feng, Chenqi; Qian, Wei; Yu, Libin; Ye, Fengying; Zhong, Qingdong; Han, Sheng

2016-12-01

The electrodeposition of Ni-nano-Cr2O3 composite coatings was studied in electrolyte containing different contents of Cr2O3 nanoparticles (Cr2O3 NPs) on mild steel surfaces. Some techniques such as X-ray diffraction (XRD), scanning electron microscopy (SEM), microhardness, the potentiodynamic polarization curves (Tafel) and electrochemical impedance spectroscopy (EIS) were used to compare pure Ni coatings and Ni-nano-Cr2O3 composite coatings. The results show that the incorporation of Cr2O3 NPs resulted in an increase of hardness and corrosion resistance, and the maximum microhardness of Ni-nano-Cr2O3 composite coatings reaches about 495 HV. The coatings exhibit an active-passive transition and relatively large impedance values. Moreover, the effect of Cr2O3 NPs on Ni electrocrystallization is also investigated by cyclic voltammetry (CV) and EIS spectroscopy, which demonstrates that the nature of Ni-based composite coatings changes attributes to Cr2O3 NPs by offering more nucleation sites and less charge transfer resistance.

In vitro investigation of nanohydroxyapatite/poly(L-lactic acid) spindle composites used for bone tissue engineering.

PubMed

Yan, W; Zhang, C Y; Xia, L L; Zhang, T; Fang, Q F

2016-08-01

Calcium phosphate ceramics such as synthetic hydroxyapatite and tricalcium phosphate are widely used in the clinic, but they stimulate less bone regeneration. In this paper, nano-hydroxyapatite/poly(L-lactic acid) (nano-HA/PLLA) spindle composites with good mechanical performance were fabricated by a modified in situ precipitation method. The HA part of composite, distributing homogenously in PLLA matrix, is spindle shape with size of 10-30 nm in diameter and 60-100 nm in length. The molar ratio of Ca/P in the synthesized nano-HA spindles was deduced as 1.52 from the EDS spectra, which is close to the stoichiometric composition of HA (Ca/P & 1.67). The compress strength is up to 150 MPa when the HA content increase to 20 %. The in vitro tests indicate that HA/PLLA bio-composites have good biodegradability and bioactivity when immersed in simulated body fluid solutions. All the results suggested that HA/PLLA nano-biocomposites are appropriate to be applied as bone substitute in bone tissue engineering.

Nano-structured polymer composites and process for preparing same

DOEpatents

Hillmyer, Marc; Chen, Liang

2013-04-16

A process for preparing a polymer composite that includes reacting (a) a multi-functional monomer and (b) a block copolymer comprising (i) a first block and (ii) a second block that includes a functional group capable of reacting with the multi-functional monomer, to form a crosslinked, nano-structured, bi-continuous composite. The composite includes a continuous matrix phase and a second continuous phase comprising the first block of the block copolymer.

Candle soot nanoparticles-polydimethylsiloxane composites for laser ultrasound transducers

NASA Astrophysics Data System (ADS)

Chang, Wei-Yi; Huang, Wenbin; Kim, Jinwook; Li, Sibo; Jiang, Xiaoning

2015-10-01

Generation of high power laser ultrasound strongly demands the advanced materials with efficient laser energy absorption, fast thermal diffusion, and large thermoelastic expansion capabilities. In this study, candle soot nanoparticles-polydimethylsiloxane (CSNPs-PDMS) composite was investigated as the functional layer for an optoacoustic transducer with high-energy conversion efficiency. The mean diameter of the collected candle soot carbon nanoparticles is about 45 nm, and the light absorption ratio at 532 nm wavelength is up to 96.24%. The prototyped CSNPs-PDMS nano-composite laser ultrasound transducer was characterized and compared with transducers using Cr-PDMS, carbon black (CB)-PDMS, and carbon nano-fiber (CNFs)-PDMS composites, respectively. Energy conversion coefficient and -6 dB frequency bandwidth of the CSNPs-PDMS composite laser ultrasound transducer were measured to be 4.41 × 10-3 and 21 MHz, respectively. The unprecedented laser ultrasound transduction performance using CSNPs-PDMS nano-composites is promising for a broad range of ultrasound therapy applications.

Microstructure evolution and mechanical properties of nano-SiCp/AZ91 composite processed by extrusion and equal channel angular pressing (ECAP)

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

Qiao, X.G.; Ying, T.

Nano-SiCp/AZ91 magnesium matrix composite was fabricated by stir casting. The as-cast ingots were extruded at 350 °C, then processed by equal channel angular pressing (ECAP) at various temperatures (250 °C, 300 °C and 350 °C). Grains are significantly refined after the extrusion and the ECAP. A basal fibre texture was detected by neutron diffraction after the extrusion, which inclines about 45° to the extrusion direction (ED) after the ECAP. Nano-scaled SiC particles agglomerate in the as-cast composite. After the extrusion, the agglomeration tends to form continuous or discontinuous strips along the extrusion direction. By application of the ECAP, the agglomeratedmore » SiC particles are partly dispersed and the strips formed during the extrusion tend to be thinner and broken with the increasing pass number. The yield tensile strength (YTS) and the ultimate tensile strength (UTS) of the composite are dramatically increased after the extrusion. ECAP for one pass at various temperatures further increases the strength, however, the YTS decreases with the increasing ECAP temperature and the pass number. The Orowan equations predict the maximum YTS of the composite may be up to 400 MPa providing SiC particles are homogenously distributed in the matrix. - Highlights: •Nano-scaled SiC particles were successfully added into AZ91 by stirring casting. •Agglomeration of nano-particles were improved by extrusion and ECAP. •Yield strength of the composite is 328 MPa after one pass of ECAP. •Further ECAP process with optimized parameters may fully disperse nano-particles. •Yield strength is predicted to up to 400 MPa when particles are fully dispersed.« less

The baffling human body and the boundless nanomaterial boon-a trap for cancer crab.

PubMed

Jeelani, S; Asokan, G S; Anuradha, G; Parthiban, J; Sivasankari, T

2014-07-01

Life is a balance of infinite physiochemical balanced harmonies and the basic unit cell is responsible in maintaining it. Cardiovascular diseases and Cancer are the prime causes of death worldwide. Cancerous cells break the harmonious balance and result in uncontrolled growth and spread. Emerging among the existing modalities for management of cancer, as a ray of hope is Nanotechnology based treatment. Dendrimers, Quantum dots and nanobubbles contribute significantly as part of nano based diagnosis and treatment in the management of cancer. Dendrimers are nanoparticles which employ the principle of Trojan horse strategy in that encapsulation and conjugation of anti cancer agents helps in targeting the cancerous cells specifically without affecting the adjacent healthy cells. Quantum dots are cadmium based nanoparticles which when exposed to UV light glow and help in destroying the cancerous cells in the incipient stage. Nanobubbles are generated with short pulses of laser, which helps in identifying the individual cancerous cells and explodes them. Apart from them other technologies such as liposomes, fullerenes, carbon nanotubes, nanoshells, paramagnetic nanoparticles, nanoburrs, respirocytes, microbiovores, nanopores, smart coating and nano bandaid contribute a great lot as boundless nanomaterial boon for the management of cancer, cardiovascular problems and overall systemic health.

Tight coupling of particle size and composition in atmospheric cloud droplet activation

NASA Astrophysics Data System (ADS)

Topping, D.; McFiggans, G.

2011-09-01

The substantial uncertainty in the indirect effect on radiative forcing in large part arises from the influences of atmospheric aerosol particles on (i) the brightness of clouds, exerting significant shortwave cooling with no appreciable compensation in the longwave, and on (ii) their ability to precipitate, with implications for cloud cover and lifetime. Predicting the ambient conditions at which aerosol particles may become cloud droplets is largely reliant on an equilibrium relationship derived in 1936. However, the theoretical basis of the relationship restricts its application to particles solely comprising involatile compounds and water, whereas a substantial fraction of particles in the real atmosphere will contain potentially thousands of semi-volatile organic compounds in addition to containing semi-volatile inorganic components such as ammonium nitrate. We show that equilibration of atmospherically reasonable concentrations of organic compounds with a growing particle as the ambient humidity increases has larger implications on cloud droplet formation than any other equilibrium compositional dependence, owing to inextricable linkage between the aerosol composition and a particles size under ambient conditions. Whilst previous attempts to account for co-condensation of gases other than water vapour have been restricted to one inorganic condensate, our method demonstrates that accounting for the co-condensation of any number of organic compounds substantially decreases the saturation ratio of water vapour required for droplet activation. This effect is far greater than any other compositional dependence; moreso even than the unphysical effect of surface tension reduction in aqueous organic mixtures, ignoring differences in bulk and surface surfactant concentrations.

Fire retardancy assessment of polypropylene composite filed with nano clay prepared from Iraqi bentonite

NASA Astrophysics Data System (ADS)

Kareem Salih, Watheq

2018-05-01

Fire retardants have an extraordinary importance because of their role in saving the people, property and reducing the damages and minimizing the dangers resulting from fires and burning of polymeric composites which are used in different civil and industrial fields. The work in this paper can be divided into two main stages. In first one nano-clay was manufactured from Iraqi bentonite and it was characterized using AFM, XRD, XRF, SEM, and BET. The AFM test showed the particle size of prepared nano clay was about 99.25 nm. In the second stage, polypropylene/nano clay composites at three low loading percents (0%,2%,4%,6%) were formulated via twin screw extruder. The fire retardancy tests included burning rate according to ASTM:D-635 and maximum flame height of flame according to ASTM:D-3014. Besides, the mechanical tests and thermal behavior of prepared samples were investigated. The results showed that (4%) of nano-clay had the maximum fire retardancy and while at (2%) loading, the maximum value of tensile strength and Yong modulus were obtained. The maximum heat of fusion was recorded for 6% nano clay sample. The final results assessment confirmed on the possibility of using low loadings of prepared nano clay to improve the fire retardancy, mechanical and thermal properties successfully.

Old Cellulose for New Multifunctional Networks

NASA Astrophysics Data System (ADS)

Yong, Geng

Cellulose is considered to be the most abundant and renewable natural polymer on earth. It is the main component of plant cells. The exploration of the utility and applications of this material and its derivatives has never stopped since human's birth. It is well known that cellulose based materials can generate films and fibers, which can be, for instance, produced from cellulosic solutions. The Cellulose rich chemical structure allows different behaviors of the polymer in solution, which is the driving force for diverse films and fibers features. The main goal of this work is the manufacture and characterization of new application of the renewable cellulosic-based materials, which are at the origin of stimuli-responsive and/or functional soft films and fibers. The several materials obtained have in common the main chain cellulose backbone but present different liquid crystalline properties. Firstly rheology coupled to nuclear magnetic resonance techniques (rheo-NMR) were used to characterize a cellulose-water based liquid crystalline solution in order to establish structure/properties relationships, which were the basis to improve the design of films and fibers produced in the framework of this work. The results achieved were at the origin of a paper published in Macromolecules. Then films were produced and due to their structure and enhanced mechanical properties, different applications were realized by producing cellulosic gratings, which mimic the periodic structures that can be found in some petals of plants and a soft cellulose moisture motor was built for the first time. Two manuscripts were published, one related to the grating mimics, in Macromolecular Chemistry and Physics, and the other one dedicated to the mechanical properties and the bending of a cellulosic film controlled by moisture action in Scientific Reports (Nature Publishing Group). Concerning cellulosic fibers, two methods were selected to fabricate micro/nano networks. In order to produce suspended aligned arrays, electrospinning was chosen due to its versatility. On the obtained nano/micro cylinders, nematic and cholesteric droplets were threaded producing necklaces of liquid crystal beads for the first time. The fiber changes not only the topology of the droplet but also distorts its spherical shape to an approximately ellipsoidal droplet. An additional cylindrical surface with planar anchoring along the droplet's long axis was also added. Designing nematic and cholesteric liquid crystal microdroplets on thin long threads opened new routes to produce fiber waveguides decorated with complex microresonators. Two Soft Matter scientific papers were published based on this work (One was chosen as the cover of that issue). Finally, nano-fibers produced by cellulose acid hydrolises were prepared and a new electro-optical sensor was built up and characterized and the results published in Liquid Crystals journal. Throughout this work Landau-de-Gennes theory was used in order to interpret and understand some of the experimental results achieved.

Chitosan-Based Nano-Embedded Microparticles: Impact of Nanogel Composition on Physicochemical Properties

PubMed Central

Islam, Paromita; Water, Jorrit J.; Bohr, Adam; Rantanen, Jukka

2016-01-01

Chitosan-based nanogels have been widely applied as drug delivery vehicles. Spray-drying of said nanogels allows for the preparation of dry powder nano-embedded microparticles. In this work, chitosan-based nanogels composed of chitosan, alginate, and/or sodium tri-penta phosphate were investigated, particularly with respect to the impact of composition on the resulting physicochemical properties. Different compositions were obtained as nanogels with sizes ranging from 203 to 561 nm. The addition of alginate and exclusion of sodium tri-penta phosphate led to an increase in nanogel size. The nanogels were subsequently spray-dried to form nano-embedded microparticles with trehalose or mannitol as matrix excipient. The microparticles of different composition were mostly spherical with a smooth surface and a mass median aerodynamic diameter of 6–10 µm. Superior redispersibility was observed for microparticles containing amorphous trehalose. This study demonstrates the potential of nano-embedded microparticles for stabilization and delivery of nanogel-based delivery systems. PMID:28025505

Synthesis of Silver Embedded Poly(o-Anisidine) Molybdophosphate Nano Hybrid Cation-Exchanger Applicable for Membrane Electrode

PubMed Central

Khan, Anish; Khan, Aftab Aslam Parwaz; Asiri, Abdullah M.; Rub, Malik Abdul

2014-01-01

Poly(o-anisidine) molybdophosphate was expediently obtained by sol-gel mixing of Poly(o-anisidine) into the inorganic matrices of molybdophosphate, which was allowed to react with silver nitrate to the formation of poly(o-anisidine) molybdophosphate embedded silver nano composite. The composite was characterized by Fourier Transform Infrared Spectroscopy, X-ray powder diffraction, UV-Vis Spectrophotometry, Fluorescence Spectroscopy, Scanning Electron Microscopy/Energy-dispersive X-ray Spectroscopy and Thermogravimertic Analysis. Ion exchange capacity and distribution studies were carried out to understand the ion-exchange capabilities of the nano composite. On the basis of highest distribution studies, this nano composite cation exchanger was used as preparation of heavy metal ion selective membrane. Membrane was characterized for its performance as porosity and swelling later on was used for the preparation of membrane electrode for Hg(II), having better linear range, wide working pH range (2–4.5) with fast response in the real environment. PMID:24805257

Chitosan-Based Nano-Embedded Microparticles: Impact of Nanogel Composition on Physicochemical Properties.

PubMed

Islam, Paromita; Water, Jorrit J; Bohr, Adam; Rantanen, Jukka

2016-12-22

Chitosan-based nanogels have been widely applied as drug delivery vehicles. Spray-drying of said nanogels allows for the preparation of dry powder nano-embedded microparticles. In this work, chitosan-based nanogels composed of chitosan, alginate, and/or sodium tri-penta phosphate were investigated, particularly with respect to the impact of composition on the resulting physicochemical properties. Different compositions were obtained as nanogels with sizes ranging from 203 to 561 nm. The addition of alginate and exclusion of sodium tri-penta phosphate led to an increase in nanogel size. The nanogels were subsequently spray-dried to form nano-embedded microparticles with trehalose or mannitol as matrix excipient. The microparticles of different composition were mostly spherical with a smooth surface and a mass median aerodynamic diameter of 6-10 µm. Superior redispersibility was observed for microparticles containing amorphous trehalose. This study demonstrates the potential of nano-embedded microparticles for stabilization and delivery of nanogel-based delivery systems.

CO oxidation on Alsbnd Au nano-composite systems

NASA Astrophysics Data System (ADS)

Rajesh, C.; Majumder, C.

2018-03-01

Using first principles method we report the CO oxidation behaviour of Alsbnd Au nano-composites in three different size ranges: Al6Au8, Al13Au42 and a periodic slab of Alsbnd Au(1 1 1) surface. The clusters prefer enclosed structures with alternating arrangement of Al and Au atoms, maximising Auδ-sbnd Alδ+ bonds. Charge distribution analysis suggests the charge transfer from Al to Au atoms, corroborated by the red shift in the density of states spectrum. Further, CO oxidation on these nano-composite systems was investigated through both Eley - Rideal and Langmuir Hinshelwood mechanism. While, these clusters interact with O2 non-dissociatively with an elongation of the Osbnd O bond, further interaction with CO led to formation of CO2 spontaneously. On contrary, the CO2 evolution by co-adsorption of O2 and CO molecules has a transition state barrier. On the basis of the results it is inferred that nano-composite material of Alsbnd Au shows significant promise toward effective oxidative catalysis.

Nano-hydroxyapatite-coated metal-ceramic composite of iron-tricalcium phosphate: Improving the surface wettability, adhesion and proliferation of mesenchymal stem cells in vitro.

PubMed

Surmeneva, Maria A; Kleinhans, Claudia; Vacun, Gabriele; Kluger, Petra Juliane; Schönhaar, Veronika; Müller, Michaela; Hein, Sebastian Boris; Wittmar, Alexandra; Ulbricht, Mathias; Prymak, Oleg; Oehr, Christian; Surmenev, Roman A

2015-11-01

Thin radio-frequency magnetron sputter deposited nano-hydroxyapatite (HA) films were prepared on the surface of a Fe-tricalcium phosphate (Fe-TCP) bioceramic composite, which was obtained using a conventional powder injection moulding technique. The obtained nano-hydroxyapatite coated Fe-TCP biocomposites (nano-HA-Fe-TCP) were studied with respect to their chemical and phase composition, surface morphology, water contact angle, surface free energy and hysteresis. The deposition process resulted in a homogeneous, single-phase HA coating. The ability of the surface to support adhesion and the proliferation of human mesenchymal stem cells (hMSCs) was studied using biological short-term tests in vitro. The surface of the uncoated Fe-TCP bioceramic composite showed an initial cell attachment after 24h of seeding, but adhesion, proliferation and growth did not persist during 14 days of culture. However, the HA-Fe-TCP surfaces allowed cell adhesion, and proliferation during 14 days. The deposition of the nano-HA films on the Fe-TCP surface resulted in higher surface energy, improved hydrophilicity and biocompatibility compared with the surface of the uncoated Fe-TCP. Furthermore, it is suggested that an increase in the polar component of the surface energy was responsible for the enhanced cell adhesion and proliferation in the case of the nano-HA-Fe-TCP biocomposites. Copyright © 2015 Elsevier B.V. All rights reserved.

Nano lead oxide and epdm composite for development of polymer based radiation shielding material: Gamma irradiation and attenuation tests

NASA Astrophysics Data System (ADS)

Özdemir, T.; Güngör, A.; Akbay, I. K.; Uzun, H.; Babucçuoglu, Y.

2018-03-01

It is important to have a shielding material that is not easily breaking in order to have a robust product that guarantee the radiation protection of the patients and radiation workers especially during the medical exposure. In this study, nano sized lead oxide (PbO) particles were used, for the first time, to obtain an elastomeric composite material in which lead oxide nanoparticles, after the surface modification with silane binding agent, was used as functional material for radiation shielding. In addition, the composite material including 1%, 5%, 10%, 15% and 20% weight percent nano sized lead oxide was irradiated with doses of 81, 100 and 120 kGy up to an irradiation period of 248 days in a gamma ray source with an initial dose rate of 21.1 Gy/h. Mechanical, thermal properties of the irradiated materials were investigated using DSC, DMA, TGA and tensile testing and modifications in thermal and mechanical properties of the nano lead oxide containing composite material via gamma irradiation were reported. Moreover, effect of bismuth-III oxide addition on radiation attenuation of the composite material was investigated. Nano lead oxide and bismuth-III oxide particles were mixed with different weight ratios. Attenuation tests have been conducted to determine lead equivalent values for the developed composite material. Lead equivalent thickness values from 0.07 to 0.65 (2-6 mm sample thickness) were obtained.

dropEst: pipeline for accurate estimation of molecular counts in droplet-based single-cell RNA-seq experiments.

PubMed

Petukhov, Viktor; Guo, Jimin; Baryawno, Ninib; Severe, Nicolas; Scadden, David T; Samsonova, Maria G; Kharchenko, Peter V

2018-06-19

Recent single-cell RNA-seq protocols based on droplet microfluidics use massively multiplexed barcoding to enable simultaneous measurements of transcriptomes for thousands of individual cells. The increasing complexity of such data creates challenges for subsequent computational processing and troubleshooting of these experiments, with few software options currently available. Here, we describe a flexible pipeline for processing droplet-based transcriptome data that implements barcode corrections, classification of cell quality, and diagnostic information about the droplet libraries. We introduce advanced methods for correcting composition bias and sequencing errors affecting cellular and molecular barcodes to provide more accurate estimates of molecular counts in individual cells.

Multifunctional polymer nano-composite based superhydrophobic surface

NASA Astrophysics Data System (ADS)

Maitra, Tanmoy; Asthana, Ashish; Buchel, Robert; Tiwari, Manish K.; Poulikakos, Dimos

2014-11-01

Superhydrophobic surfaces become desirable in plethora of applications in engineering fields, automobile industry, construction industries to name a few. Typical fabrication of superhydrophobic surface consists of two steps: first is to create rough morphology on the substrate of interest, followed by coating of low energy molecules. However, typical exception of the above fabrication technique would be direct coating of functional polymer nanocomposites on substrate where superhydrophobicity is needed. Also in this case, the use of different nanoparticles in the polymer matrix can be exploited to impart multi-functional properties to the superhydrophobic coatings. Herein, different carbon nanoparticles like graphene nanoplatelets (GNP), carbon nanotubes (CNT) and carbon black (CB) are used in fluropolymer matrix to prepare superhydrophobic coatings. The multi-functional properties of coatings are enhanced by combining two different carbon fillers in the matrix. The aforementioned superhydrophobic coatings have shown high electrical conductivity and excellent droplet meniscus impalement resistance. Simultaneous superhydrophobic and oleophillic character of the above coating is used to separate mineral oil and water through filtration of their mixture. Swiss National Science Foundation (SNF) Grant 200021_135479.

Preparation of hydroxyapatite/poly(lactic acid) hybrid microparticles for local drug delivery

NASA Astrophysics Data System (ADS)

Loca, D.; Locs, J.; Berzina-Cimdina, L.

2013-12-01

Calcium phosphate (CaP) bioceramic is well known as bioactive and biocompatible material in bone tissue regeneration applications. Apatitic CaP, especially nano sized hydroxyapatite (NHAp), is more similar to the natural apatite presented in the bone tissue than CaP bioceramics. In the current research NHAp was modified using biodegradable polymer - poly(lactic acid) (PLA) to develop composites providing bone regeneration and local drug delivery. NHAp/PLA microcapsules were prepared using solid-in-water-in-oil-in-water (s/w1/o/w2) encapsulation technology. The impact of primary and secondary emulsion stability on the emulsion droplet and microparticle properties was evaluated. The stability of final emulsion can be increased by varying the process parameters. Stable s/w1/o/w2 emulsion using 3ml of NHAp suspension, not less than 100ml of 4% PVA water solution and 10ml of 10% PLA solution in dichloromethane can be obtained. S/w1/o/w2 microencapuslation method can be effectively used for the preparation of multi-domain microcapsules achieving high NHAp encapsulation efficacy (93%).

"Solvent-in-salt" systems for design of new materials in chemistry, biology and energy research.

PubMed

Azov, Vladimir A; Egorova, Ksenia S; Seitkalieva, Marina M; Kashin, Alexey S; Ananikov, Valentine P

2018-02-21

Inorganic and organic "solvent-in-salt" (SIS) systems have been known for decades but have attracted significant attention only recently. Molten salt hydrates/solvates have been successfully employed as non-flammable, benign electrolytes in rechargeable lithium-ion batteries leading to a revolution in battery development and design. SIS with organic components (for example, ionic liquids containing small amounts of water) demonstrate remarkable thermal stability and tunability, and present a class of admittedly safer electrolytes, in comparison with traditional organic solvents. Water molecules tend to form nano- and microstructures (droplets and channel networks) in ionic media impacting their heterogeneity. Such microscale domains can be employed as microreactors for chemical and enzymatic synthesis. In this review, we address known SIS systems and discuss their composition, structure, properties and dynamics. Special attention is paid to the current and potential applications of inorganic and organic SIS systems in energy research, chemistry and biochemistry. A separate section of this review is dedicated to experimental methods of SIS investigation, which is crucial for the development of this field.

Synthesis and characterization of beta-Ga2O3 nanorod array clumps by chemical vapor deposition.

PubMed

Shi, Feng; Wei, Xiaofeng

2012-11-01

beta-Ga2O3 nanorod array clumps were successfully synthesized on Si (111) substrates by chemical vapor deposition. The composition, microstructure, morphology, and light-emitting property of these clumps were characterized by X-ray diffraction, Fourier transform infrared spectrophotometry, X-ray photoelectron spectroscopy, scanning electron microscopy, high-resolution transmission electron microscopy, Raman spectroscopy, and photoluminescence. The results demonstrate that the sample synthesized at 1050 degrees C for 15 min was composed of monoclinic beta-Ga2O3 nanorod array clumps, where each single nanorod was about 300 nm in diameter with some nano-droplets on its tip. These results reveal that the growth mechanism agrees with the vapor-liquid-solid (VLS) process. The photoluminescence spectrum shows that the Ga2O3 nanorods have a blue emission at 438 nm, which may be attributed to defects, such as oxygen vacancies and gallium-oxygen vacancy pairs. Defect-energy aggregation confinement growth theory was proposed to explain the growth mechanism of Ga2O3 nanorod array clumps collaborated with the VLS mechanism.

Co-Compartmentation of Terpene Biosynthesis and Storage via Synthetic Droplet

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

Zhao, Cheng; Kim, YongKyoung; Zeng, Yining

Traditional bioproduct engineering focuses on pathway optimization, yet is often complicated by product inhibition, downstream consumption, and the toxicity of certain products. Here, we present the co-compartmentation of biosynthesis and storage via a synthetic droplet as an effective new strategy to improve the bioproduct yield, with squalene as a model compound. A hydrophobic protein was designed and introduced into the tobacco chloroplast to generate a synthetic droplet for terpene storage. Simultaneously, squalene biosynthesis enzymes were introduced to chloroplasts together with the droplet-forming protein to co-compartmentalize the biosynthesis and storage of squalene. The strategy has enabled a record yield of squalenemore » at 2.6 mg/g fresh weight without compromising plant growth. Confocal fluorescent microscopy imaging, stimulated Raman scattering microscopy, and droplet composition analysis confirmed the formation of synthetic storage droplet in chloroplast. The co-compartmentation of synthetic storage droplet with a targeted metabolic pathway engineering represents a new strategy for enhancing bioproduct yield.« less

Co-Compartmentation of Terpene Biosynthesis and Storage via Synthetic Droplet

DOE PAGES

Zhao, Cheng; Kim, YongKyoung; Zeng, Yining; ...

2018-02-13

Traditional bioproduct engineering focuses on pathway optimization, yet is often complicated by product inhibition, downstream consumption, and the toxicity of certain products. Here, we present the co-compartmentation of biosynthesis and storage via a synthetic droplet as an effective new strategy to improve the bioproduct yield, with squalene as a model compound. A hydrophobic protein was designed and introduced into the tobacco chloroplast to generate a synthetic droplet for terpene storage. Simultaneously, squalene biosynthesis enzymes were introduced to chloroplasts together with the droplet-forming protein to co-compartmentalize the biosynthesis and storage of squalene. The strategy has enabled a record yield of squalenemore » at 2.6 mg/g fresh weight without compromising plant growth. Confocal fluorescent microscopy imaging, stimulated Raman scattering microscopy, and droplet composition analysis confirmed the formation of synthetic storage droplet in chloroplast. The co-compartmentation of synthetic storage droplet with a targeted metabolic pathway engineering represents a new strategy for enhancing bioproduct yield.« less

In Vitro Cytotoxicity Assessment of an Orthodontic Composite Containing Titanium-dioxide Nano-particles

PubMed Central

Heravi, Farzin; Ramezani, Mohammad; Poosti, Maryam; Hosseini, Mohsen; Shajiei, Arezoo; Ahrari, Farzaneh

2013-01-01

Background and aims. Incorporation of nano-particles to orthodontic bonding systems has been considered to prevent enamel demineralization around appliances. This study investigated cytotoxicity of Transbond XT adhesive containing 1 wt% titanium dioxide (TiO2) nano-particles. Materials and methods. Ten composite disks were prepared from each of the conventional and TiO2-containg composites and aged for 1, 3, 5, 7 and 14 days in Dulbecco’s Modified Eagle’s Medium (DMEM). The extracts were obtained and exposed to culture media of human gingival fibroblasts (HGF) and mouse L929 fibroblasts. Cell viability was measured using the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay. Results. Both adhesives were moderately toxic for HGF cells on the first day of the experiment, but the TiO2-containing adhesive produced significantly lower toxicity than the pure adhesive (P<0.05). No significant differences were found in cell viability percentages between the two groups on the other days (P>0.05). There was a significant reduction in cell toxicity with increasing pre-incubation time (P<0.001). L929 cells showed similar toxicity trends, but lower sensitivity to detect cytotoxicity of dental composites. Conclusion. The orthodontic adhesive containing TiO2 nano-particles indicated comparable or even lower toxicity than its nano-particle-free counterpart, indicating that incorporation of 1 wt% TiO2 nano-particles to the composite structure does not result in additional health hazards compared to that occurring with the pure adhesive. PMID:24578816

Biocompatible fluorinated polyglycerols for droplet microfluidics as an alternative to PEG-based copolymer surfactants.

PubMed

Wagner, Olaf; Thiele, Julian; Weinhart, Marie; Mazutis, Linas; Weitz, David A; Huck, Wilhelm T S; Haag, Rainer

2016-01-07

In droplet-based microfluidics, non-ionic, high-molecular weight surfactants are required to stabilize droplet interfaces. One of the most common structures that imparts stability as well as biocompatibility to water-in-oil droplets is a triblock copolymer surfactant composed of perfluoropolyether (PFPE) and polyethylene glycol (PEG) blocks. However, the fast growing applications of microdroplets in biology would benefit from a larger choice of specialized surfactants. PEG as a hydrophilic moiety, however, is a very limited tool in surfactant modification as one can only vary the molecular weight and chain-end functionalization. In contrast, linear polyglycerol offers further side-chain functionalization to create custom-tailored, biocompatible droplet interfaces. Herein, we describe the synthesis and characterization of polyglycerol-based triblock surfactants with tailored side-chain composition, and exemplify their application in cell encapsulation and in vitro gene expression studies in droplet-based microfluidics.

Scanning electron microscope study of Apollo 15 green glass

NASA Technical Reports Server (NTRS)

Mckay, D. S.; Clanton, U. S.; Ladle, G.

1973-01-01

Apollo 15 green glass droplets and related forms show a variety of low velocity impact features which occurred at the time of formation of the droplets. Composite forms, which consist of a crystallized core on which mounds of glass adhere, indicate a sequence of core formation and crystallization, followed by impact of molten droplets. The complicated and time dependent texture and morphology of the green glass forms are best explained by formation in a volcanic lava fountain rather than by meteorite impact.

Computational Prediction of Cryogenic Micro-nano Solid Nitrogen Particle Production Using Laval Nozzle for Physical Photo Resist Removal-cleaning Technology

NASA Astrophysics Data System (ADS)

Ishimoto, Jun; Abe, Haruto; Ochiai, Naoya

The fundamental characteristics of the cryogenic single-component micro-nano solid nitrogen (SN2) particle production using super adiabatic Laval nozzle and its application to the physical photo resist removal-cleaning technology are investigated by a new type of integrated measurement coupled computational technique. As a result of present computation, it is found that high-speed ultra-fine SN2 particles are continuously generated due to the freezing of liquid nitrogen (LN2) droplets induced by rapid adiabatic expansion of transonic subcooled two-phase nitrogen flow passing through the Laval nozzle. Furthermore, the effect of SN2 particle diameter, injection velocity, and attack angle to the wafer substrate on resist removal-cleaning performance is investigated in detail by integrated measurement coupled computational technique.

Surface morphology and electrochemical studies on polyaniline/CuO nano composites

NASA Astrophysics Data System (ADS)

Ashokkumar, S. P.; Vijeth, H.; Yesappa, L.; Niranjana, M.; Vandana, M.; Basappa, M.; Devendrappa, H.

2018-05-01

An electrochemically synthesized Polyaniline (PANI) and Polyaniline/copper oxide (PCN) nano composite have studied the morphology and electrochemical properties. The composite is characterized by X-ray diffraction (XRD) and surface morphology was studied using FESEM and electrochemical behavior is studied using cyclic voltammetry (CV) technique. The CV curves shows rectangular shaped curve and they have contribution to electrical double layer capacitance (EDCL).

Preparation of silver nano-particles immobilized onto chitin nano-crystals and their application to cellulose paper for imparting antimicrobial activity.

PubMed

Li, Zhihan; Zhang, Ming; Cheng, Dong; Yang, Rendang

2016-10-20

Immobilized silver nano-particles (Ag NPs) possess excellent antimicrobial properties due to their unique surface characteristics. In this paper, immobilized silver nano-particles were synthesized in the presence of chitin nano-crystals (CNC) based on the Tollens mechanism (reduction of silver ion by aldehydes in the chitosan oligosaccharides (COS)) under microwave-assisted conditions. The prepared Ag NPs-loaded CNC nano-composites were then applied onto the paper surface via coating for the preparation of antibacterial paper. Fourier transform infrared (FT-IR) and X-ray diffraction (XRD) results confirmed that the Ag NPs were immobilized onto the CNC. The transmission electron microscope (TEM) and scanning electron microscopy (SEM) results further revealed that the spherical Ag NPs (5-12nm) were well dispersed on the surface of CNC. The coated paper made from the Ag NPs-loaded CNC nano-composites exhibited a high effectiveness of the antibacterial activity against E. coli or S. aureus. Copyright © 2016 Elsevier Ltd. All rights reserved.

Parallel generation of uniform fine droplets at hundreds of kilohertz in a flow-focusing module.

PubMed

Bardin, David; Kendall, Michael R; Dayton, Paul A; Lee, Abraham P

2013-01-01

Droplet-based microfluidic systems enable a variety of biomedical applications from point-of-care diagnostics with third world implications, to targeted therapeutics alongside medical ultrasound, to molecular screening and genetic testing. Though these systems maintain the key advantage of precise control of the size and composition of the droplet as compared to conventional methods of production, the low rates at which droplets are produced limits translation beyond the laboratory setting. As well, previous attempts to scale up shear-based microfluidic systems focused on increasing the volumetric throughput and formed large droplets, negating many practical applications of emulsions such as site-specific therapeutics. We present the operation of a parallel module with eight flow-focusing orifices in the dripping regime of droplet formation for the generation of uniform fine droplets at rates in the hundreds of kilohertz. Elevating the capillary number to access dripping, generation of monodisperse droplets of liquid perfluoropentane in the parallel module exceeded 3.69 × 10(5) droplets per second, or 1.33 × 10(9) droplets per hour, at a mean diameter of 9.8 μm. Our microfluidic method offers a novel means to amass uniform fine droplets in practical amounts, for instance, to satisfy clinical needs, with the potential for modification to form massive amounts of more complex droplets.

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

PubMed Central

Benea, Lidia; Celis, Jean-Pierre

2016-01-01

This research work describes the effect of dispersed titanium carbide (TiC) nanoparticles into nickel plating bath on Ni/TiC nanostructured composite layers obtained by electro-codeposition. The surface morphology of Ni/TiC nanostructured composite layers was characterized by scanning electron microscopy (SEM). The composition of coatings and the incorporation percentage of TiC nanoparticles into Ni matrix were studied and estimated by using energy dispersive X-ray analysis (EDX). X-ray diffractometer (XRD) has been applied in order to investigate the phase structure as well as the corresponding relative texture coefficients of the composite layers. The results show that the concentration of nano-TiC particles added in the nickel electrolyte affects the inclusion percentage of TiC into Ni/TiC nano strucured layers, as well as the corresponding morphology, relative texture coefficients and thickness indicating an increasing tendency with the increasing concentration of nano-TiC concentration. By increasing the amount of TiC nanoparticles in the electrolyte, their incorporation into nickel matrix also increases. The hybrid Ni/nano-TiC composite layers obtained revealed a higher roughness and higher hardness; therefore, these layers are promising superhydrophobic surfaces for special application and could be more resistant to wear than the pure Ni layers. PMID:28773395

The effect of remin pro and MI paste plus on bleached enamel surface roughness.

PubMed

Ahmad Akhoundi, Mohammad Sadegh; Aghajani, Farzaneh; Chalipa, Javad; Sadrhaghighi, Amir Hooman

2014-03-01

Increased number of adult patients requesting orthodontic treatment result in bonding bracket to ceramic restorations more than before. The aim of this study was to evaluate and compare the shear bond strength of orthodontic brackets bonded to two types of ceramic bases with conventional orthodontic bonding resin and a new nano-filled composite resin. Twenty four feldespathic porcelain and 24 lithium disilicate ceramic disks were fabricated. All of the samples were conditioned by sandblasting, hydrofluoric acid and silane. Maxillary incisor metal brackets were bonded to half of the disks in each group by conventional orthodontic bonding resin and the other half bonded with a nano-filled composite. The samples then were thermocycled for 2000 cycle between 5-55° C. Shear bond strength was measured and the mode of failure was examined. Randomly selected samples were also evaluated by SEM. The lowest bond strength value was found infeldespathic ceramic bonded by nano-filled composite (p<0.05). There was not any statistically significant difference between other groups regarding bond strength. The mode of failure in the all groups except group 1 was cohesive and porcelain damages were detected. Since less damages to feldspathic porcelain was observed when the nano-filled composite was used to bond brackets, the use of nano-filled composite resins can be suggested for bonding brackets to feldspathic porcelain restorations.

The Effect of Remin Pro and MI Paste Plus on Bleached Enamel Surface Roughness

PubMed Central

Ahmad Akhoundi, Mohammad Sadegh; Aghajani, Farzaneh; Chalipa, Javad; Sadrhaghighi, Amir Hooman

2014-01-01

Objective Increased number of adult patients requesting orthodontic treatment result in bonding bracket to ceramic restorations more than before. The aim of this study was to evaluate and compare the shear bond strength of orthodontic brackets bonded to two types of ceramic bases with conventional orthodontic bonding resin and a new nano-filled composite resin. Materials and Methods: Twenty four feldespathic porcelain and 24 lithium disilicate ceramic disks were fabricated. All of the samples were conditioned by sandblasting, hydrofluoric acid and silane. Maxillary incisor metal brackets were bonded to half of the disks in each group by conventional orthodontic bonding resin and the other half bonded with a nano-filled composite. The samples then were thermocycled for 2000 cycle between 5–55° C. Shear bond strength was measured and the mode of failure was examined. Randomly selected samples were also evaluated by SEM. Results: The lowest bond strength value was found infeldespathic ceramic bonded by nano-filled composite (p<0.05). There was not any statistically significant difference between other groups regarding bond strength. The mode of failure in the all groups except group 1 was cohesive and porcelain damages were detected. Conclusion: Since less damages to feldspathic porcelain was observed when the nano-filled composite was used to bond brackets, the use of nano-filled composite resins can be suggested for bonding brackets to feldspathic porcelain restorations. PMID:24910698

Engineered electrospun poly(caprolactone)/polycaprolactone-g-hydroxyapatite nano-fibrous scaffold promotes human fibroblasts adhesion and proliferation.

PubMed

Keivani, F; Shokrollahi, P; Zandi, M; Irani, S; F Shokrolahi; Khorasani, S C

2016-11-01

Polycaprolactone (PCL)/hydroxyapatite nano-composites are among the best candidates for tissue engineering. However, interactions between nHAp and PCL are difficult to control leading to inhomogeneous dispersion of the bio-ceramic particles. Grafting of polymer chains at high density/chain length while promotes the phase compatibility may result in reduced HAp exposed surface area and therefore, bioactivity is compromised. This issue is addressed here by grafting PCL chains onto HAp nano-particles through ring opening polymerization of ε-caprolactone (PCL-g-HAp). FTIR and TGA analysis showed that PCL (6.9wt%), was successfully grafted on the HAp. PCL/PCL-g-HAp nano-fibrous scaffold showed up to 10 and 33% enhancement in tensile strength and modulus, respectively, compared to those of PCL/HAp. The effects of HAp on the in vitro HAp formation were investigated for both the PCL/HAp and PCL/PCL-g-HAp scaffolds. Precipitation of HAp on the nano-composite scaffolds observed after 15days incubation in simulated body fluid (SBF), as confirmed by scanning electron microscopy (SEM), and energy dispersive X-ray spectroscopy (EDX). Human fibroblasts were seeded on PCL, PCL/HAp and PCL/PCL-g-HAp scaffolds. According to MTT assay, the highest cell proliferation was recorded for PCL/PCL-g-HAp nano-composite, at all time intervals (1-21days, P<0.001). Fluorescent microscopy (of DAPI stained samples) and electron microscopy images showed that all nano-fibrous scaffolds (PCL, PCL/HAp, and PCL/PCL-g-HAp), were non-toxic against cells, while more cell adhesion, and the most uniform cell distribution observed on the PCL/PCL-g-HAp. Overall, grafting of relatively short chains of PCL on the surface of HAp nano-particles stimulates fibroblasts adhesion and proliferation on the PCL/PCL-g-HAp nano-composite. Copyright © 2016 Elsevier B.V. All rights reserved.

Patterning of Thick Parylene Films by Oxygen Plasma for Application as Exploding Foil Initiator Flyer Material

DTIC Science & Technology

2009-09-01

exploding foil initiator ( EFI ) type fuzes are being explored to...Acronyms Au gold Cr chromium Cu copper EFI exploding foil initiator BOE buffered oxide etch MEMS microelectromechanical systems RIE reactive ion...Patterning of Thick Parylene Films by Oxygen Plasma for Application as Exploding Foil Initiator Flyer Material by Eugene Zakar and Michael

Biogenic, urban, and wildfire influences on the molecular composition of dissolved organic compounds in cloud water

NASA Astrophysics Data System (ADS)

Cook, Ryan D.; Lin, Ying-Hsuan; Peng, Zhuoyu; Boone, Eric; Chu, Rosalie K.; Dukett, James E.; Gunsch, Matthew J.; Zhang, Wuliang; Tolic, Nikola; Laskin, Alexander; Pratt, Kerri A.

2017-12-01

Organic aerosol formation and transformation occurs within aqueous aerosol and cloud droplets, yet little is known about the composition of high molecular weight organic compounds in cloud water. Cloud water samples collected at Whiteface Mountain, New York, during August-September 2014 were analyzed by ultra-high-resolution mass spectrometry to investigate the molecular composition of dissolved organic carbon, with a focus on sulfur- and nitrogen-containing compounds. Organic molecular composition was evaluated in the context of cloud water inorganic ion concentrations, pH, and total organic carbon concentrations to gain insights into the sources and aqueous-phase processes of the observed high molecular weight organic compounds. Cloud water acidity was positively correlated with the average oxygen : carbon ratio of the organic constituents, suggesting the possibility for aqueous acid-catalyzed (prior to cloud droplet activation or during/after cloud droplet evaporation) and/or radical (within cloud droplets) oxidation processes. Many tracer compounds recently identified in laboratory studies of bulk aqueous-phase reactions were identified in the cloud water. Organosulfate compounds, with both biogenic and anthropogenic volatile organic compound precursors, were detected for cloud water samples influenced by air masses that had traveled over forested and populated areas. Oxidation products of long-chain (C10-12) alkane precursors were detected during urban influence. Influence of Canadian wildfires resulted in increased numbers of identified sulfur-containing compounds and oligomeric species, including those formed through aqueous-phase reactions involving methylglyoxal. Light-absorbing aqueous-phase products of syringol and guaiacol oxidation were observed in the wildfire-influenced samples, and dinitroaromatic compounds were observed in all cloud water samples (wildfire, biogenic, and urban-influenced). Overall, the cloud water molecular composition depended on air mass source influence and reflected aqueous-phase reactions involving biogenic, urban, and biomass burning precursors.

Preparation and characteristic of gelatine/oxidized corn starch and gelatin/corn starch blend microspheres.

PubMed

Chen, Hui; Shan, Zhi Hua; Woo, Meng Wai; Chen, Xiao Dong

2017-01-01

Combinations of gelatin (G) and oxidized corn starch (OCS) were explored as a new microcapsule composite for single droplet spray drying. The blending solutions property, gel time, transparency and viscosity of G/CS (corn starch) and G/OCS blend solutions were compared at different ratios (10:0;9:1;8:2;7:3;6:4;5:5) and concentrations(1%wt; 3%wt; 5%wt). The drying and dissolution behaviors of composite droplet have been studied using the single droplet drying technique. Possible reaction mechanisms in the composite blend were elucidated by SEM and FTIR techniques. Blends solutions of G/OCS showed longer Gel time, higher transparency and lower viscosity; further displayed faster dissolution rate than that of G/CS under similar conditions. This was attributed to the formed Schiff base between the aldehyde group of OCS and amino group of G which improved the compatibility between G and OCS. All results indicated that the composites could be prepared with excellent properties by G/OCS (6:4) which would overcome some disadvantage such as thermodynamic incompatibility and phase separation by G/CS. Copyright © 2016. Published by Elsevier B.V.

Dispersion of Multi-Walled Carbon Nanotubes in Skutterudites and Its Effect on Thermoelectric and Mechanical Properties.

PubMed

Schmitz, Andreas; Schmid, Carolin; de Boor, Johannes; Müller, Eckhard

2017-03-01

Filled cobalt-antimony based skutterudites have proven themselves as very promising thermoelectric materials for generator applications in an intermediate temperature range between 400 and 800 K due to their high figure of merit. Besides the functional thermoelectric properties also the skutterudites’ mechanical properties play an important role to withstand external mechanical and internal thermomechanical loads during operation. Properties of interest are hardness as well as fracture toughness and resistance to fatigue. Carbon nano tubes are well known for their high tensile strength and may therefore be used to increase the mechanical strength of composite materials. Additionally, the thermoelectric properties of the composite material might benefit from the high electrical conductivity of carbon nano tubes and increased phonon scattering at interfaces between matrix and carbon nano tube. A main precondition for benefiting from embedded nano-tubes is to achieve a homogeneous distribution of the CNTs and good adhesion between carbon nano tube and matrix material. In this work we present the influence of the introduction of multi-walled carbon nano tubes on the thermoelectric and mechanical properties of p-type skutterudites Ce(0.14)La(0.06)Co(2)Fe(2)Sb(12). The influence of different carbon nano tube concentrations and preparation routes on the resulting composite material’s thermoelectric, mechanical and microstructural properties is studied. A reduction of electrical and thermal conductivity as well as fracture strength is observed with increasing carbon nano tube content which is attributed to strong agglomeration of the nano tubes. The results underline the pivotal role of a homogeneous distribution of the carbon nano tubes for improving the mechanical properties of skutterudites.

Method for making generally cylindrical underground openings

DOEpatents

Routh, J.W.

1983-05-26

A rapid, economical and safe method for making a generally cylindrical underground opening such as a shaft or a tunnel is described. A borehole is formed along the approximate center line of where it is desired to make the underground opening. The borehole is loaded with an explodable material and the explodable material is detonated. An enlarged cavity is formed by the explosive action of the detonated explodable material forcing outward and compacting the original walls of the borehole. The enlarged cavity may be increased in size by loading it with a second explodable material, and detonating the second explodable material. The process may be repeated as required until the desired underground opening is made. The explodable material used in the method may be free-flowing, and it may be contained in a pipe.

Characterization of Electrical Properties of Polymers for Conductive Nano-Composites

DTIC Science & Technology

2011-05-01

Research Triangle Park, NC 27709-2211 15. SUBJECT TERMS Nano composites, piezo -resistivity, quantum tunneling Oliver K. Johnson, Daniel Seegmiller, David T...plate component of the circuit (i.e. ) with known resistors from 1Ω to 2×10 9 Ω and recording the corresponding output voltage. Using this

Thermal and mechanical properties of compression-moulded poly(lactic acid)/gluten/clays bio(nano)composites

USDA-ARS?s Scientific Manuscript database

Bio(nano)composites comprising agricultural-based polymers blended with biodegradable plant-based fillers and clays were produced to develop novel hydrophobic, yet biodegradable materials that have properties comparable to those of petroleum-based plastics. Poly (lactic acid) (PLA), wheat vital glut...

Positron annihilation lifetime study of Nafion/titanium dioxide nano-composite membranes

NASA Astrophysics Data System (ADS)

Lei, M.; Wang, Y. J.; Liang, C.; Huang, K.; Ye, C. X.; Wang, W. J.; Jin, S. F.; Zhang, R.; Fan, D. Y.; Yang, H. J.; Wang, Y. G.

2014-01-01

Positron annihilation lifetime (PAL) technique is applied for investigation of size and number density of free volumes in Nafion/TiO2-nanoparticles composite membrane. The proton transporting ability is correlated with the properties of free volume inside the membrane. It is revealed that composite membrane with 5 wt% of TiO2 nano-fillers exhibits good electrochemical performance under reduced humidity and it can be saturated with water at relative humidity of 50%, under which ionic clusters and proton transporting channels are formed, indicating that composite membranes with 5 wt% of TiO2 nano-fillers are effective electrolyte for fuel cells operated at reduced humidification levels. The results suggest that PAL can be a powerful tool for elucidating the relationship between microstructure and ion transport in polymer electrolyte membranes.

Ignition of a Droplet of Composite Liquid Fuel in a Vortex Combustion Chamber

NASA Astrophysics Data System (ADS)

Valiullin, T. R.; Vershinina, K. Yu; Glushkov, D. O.; Strizhak, P. A.

2017-11-01

Experimental study results of a droplet ignition and combustion were obtained for coal-water slurry containing petrochemicals (CWSP) prepared from coal processing waste, low-grade coal and waste petroleum products. A comparative analysis of process characteristics were carried out in different conditions of fuel droplet interaction with heated air flow: droplet soars in air flow in a vortex combustion chamber, droplet soars in ascending air flow in a cone-shaped combustion chamber, and droplet is placed in a thermocouple junction and motionless in air flow. The size (initial radii) of CWSP droplet was varied in the range of 0.5-1.5 mm. The ignition delay time of fuel was determined by the intensity of the visible glow in the vicinity of the droplet during CWSP combustion. It was established (under similar conditions) that ignition delay time of CWSP droplets in the combustion chamber is lower in 2-3.5 times than similar characteristic in conditions of motionless droplet placed in a thermocouple junction. The average value of ignition delay time of CWSP droplet is 3-12 s in conditions of oxidizer temperature is 600-850 K. Obtained experimental results were explained by the influence of heat and mass transfer processes in the droplet vicinity on ignition characteristics in different conditions of CWSP droplet interaction with heated air flow. Experimental results are of interest for the development of combustion technology of promising fuel for thermal power engineering.

Room-temperature solution-processed and metal oxide-free nano-composite for the flexible transparent bottom electrode of perovskite solar cells

NASA Astrophysics Data System (ADS)

Lu, Haifei; Sun, Jingsong; Zhang, Hong; Lu, Shunmian; Choy, Wallace C. H.

2016-03-01

The exploration of low-temperature and solution-processed charge transporting and collecting layers can promote the development of low-cost and large-scale perovskite solar cells (PVSCs) through an all solution process. Here, we propose a room-temperature solution-processed and metal oxide-free nano-composite composed of a silver nano-network and graphene oxide (GO) flawless film for the transparent bottom electrode of a PVSC. Our experimental results show that the amount of GO flakes play a critical role in forming the flawless anti-corrosive barrier in the silver nano-network through a self-assembly approach under ambient atmosphere, which can effectively prevent the penetration of liquid or gaseous halides and their corrosion against the silver nano-network underneath. Importantly, we simultaneously achieve good work function alignment and surface wetting properties for a practical bottom electrode by controlling the degree of reduction of GO flakes. Finally, flexible PVSC adopting the room-temperature and solution-processed nano-composite as the flexible transparent bottom electrode has been demonstrated on a polyethylene terephthalate (PET) substrate. As a consequence, the demonstration of our room-temperature solution-processed and metal oxide-free flexible transparent bottom electrode will contribute to the emerging large-area flexible PVSC technologies.The exploration of low-temperature and solution-processed charge transporting and collecting layers can promote the development of low-cost and large-scale perovskite solar cells (PVSCs) through an all solution process. Here, we propose a room-temperature solution-processed and metal oxide-free nano-composite composed of a silver nano-network and graphene oxide (GO) flawless film for the transparent bottom electrode of a PVSC. Our experimental results show that the amount of GO flakes play a critical role in forming the flawless anti-corrosive barrier in the silver nano-network through a self-assembly approach under ambient atmosphere, which can effectively prevent the penetration of liquid or gaseous halides and their corrosion against the silver nano-network underneath. Importantly, we simultaneously achieve good work function alignment and surface wetting properties for a practical bottom electrode by controlling the degree of reduction of GO flakes. Finally, flexible PVSC adopting the room-temperature and solution-processed nano-composite as the flexible transparent bottom electrode has been demonstrated on a polyethylene terephthalate (PET) substrate. As a consequence, the demonstration of our room-temperature solution-processed and metal oxide-free flexible transparent bottom electrode will contribute to the emerging large-area flexible PVSC technologies. Electronic supplementary information (ESI) available. See DOI: 10.1039/c6nr00011h

Diffusion, swelling, cross linkage study and mechanical properties of ZnO doped PVA/NaAlg blend polymer nanocomposite

NASA Astrophysics Data System (ADS)

Guruswamy, B.; Ravindrachary, V.; Shruthi, C.; Hegde, Shreedatta; Sagar, Rohan N.

2018-04-01

ZnO nano particles were synthesized using a chemical precipitation method. Pure and ZnO nano particle doped PVA-NaAlg blend composite films were prepared using solution casing method. Structural information of these composites was studied using FTIR. Diffusion kinetics of these polymer blend composite were studied using Flory-Huggins theory. Using these diffusion studies, cross-linking density and swelling properties of the films were analyzed. Mechanical properties of these composite are also studied.

Synthesis and Characterization of Multi Wall Carbon Nanotubes (MWCNT) Reinforced Sintered Magnesium Matrix Composites

NASA Astrophysics Data System (ADS)

Vijaya Bhaskar, S.; Rajmohan, T.; Palanikumar, K.; Bharath Ganesh Kumar, B.

2016-04-01

Metal matrix composites (MMCs) reinforced with ceramic nano particles (less than 100 nm), termed as metal matrix nano composites (MMNCs), can overcome those disadvantages associated with the conventional MMCs. MMCs containing carbon nanotubes are being developed and projected for diverse applications in various fields of engineering like automotive, avionic, electronic and bio-medical sectors. The present investigation deals with the synthesis and characterization of hybrid magnesium matrix reinforced with various different wt% (0-0.45) of multi wall carbon nano tubes (MWCNT) and micro SiC particles prepared through powder metallurgy route. Microstructure and mechanical properties such as micro hardness and density of the composites were examined. Microstructure of MMNCs have been investigated by scanning electron microscope, X-ray diffraction and energy dispersive X-ray spectroscopy (EDS) for better observation of dispersion of reinforcement. The results indicated that the increase in wt% of MWCNT improves the mechanical properties of the composite.

A new simple synthesis of CdS nano-particles by composite-molten-salt method and their high photocatalytic degradation activity

NASA Astrophysics Data System (ADS)

Xiang, Donghu; Zhu, Yabo; Cai, Cunjin; He, Zhanjun; Liu, Zhangsheng; Yin, Dagen; Luo, Jin

2011-12-01

Nano-CdS crystal has been succesfully synthesized by composite molten salt (CMS) method for the first time, using composite molten salt as a reaction solvent, sodium sulfide and cadmium nitrate hexahydrate as reactants at temperature of 200 °C for 24 h in the absence of organic dispersant or capping agents. X-ray diffraction and field emission scanning electron microscopy (FESEM) images indicated that the as-synthesized product were well crystallized and belonged to nano-scale. Their UV-vis absorption spectrum demonstrated a band gap of 2.49 eV corresponding to the absorption edge of 499 nm. The experimental result of photocatalytic degradation on methyl orange by the nano-CdS showed much better photocatalysis than that by the commercial CdS powder under the irradiation of ultraviolet light source.

Droplet Combustion Experiment Operates

NASA Technical Reports Server (NTRS)

2003-01-01

Fuel ignites and burns in the Droplet Combustion Experiment (DCE) on STS-94 on July 12, 1997, MET:11/07:00 (approximate). DCE used various fuels -- in drops ranging from 1 mm (0.04 inches) to 5 mm (0.2 inches) -- and mixtures of oxidizers and inert gases to learn more about the physics of combustion in the simplest burning configuration, a sphere. The DCE was designed to investigate the fundamental combustion aspects of single, isolated droplets under different pressures and ambient oxygen concentrations for a range of droplet sizes varying between 2 and 5 mm. The experiment elapsed time is shown at the bottom of the composite image. The DCE principal investigator was Forman Williams, University of California, San Diego. The experiment was part of the space research investigations conducted during the Microgravity Science Laboratory-1R mission (STS-94, July 1-17 1997). Advanced combustion experiments will be a part of investigations plarned for the International Space Station. (119KB JPEG, 658 x 982 pixels; downlinked video, higher quality not available) The MPG from which this composite was made is available at http://mix.msfc.nasa.gov/ABSTRACTS/MSFC-0300171.html.

Burning Fuel Droplet

NASA Technical Reports Server (NTRS)

2003-01-01

Fuel ignites and burns in the Droplet Combustion Experiment (DCE) on STS-94 on July 4 1997, MET:2/05:40 (approximate). The DCE was designed to investigate the fundamental combustion aspects of single, isolated droplets under different pressures and ambient oxygen concentrations for a range of droplet sizes varying between 2 and 5 mm. DCE used various fuels -- in drops ranging from 1 mm (0.04 inches) to 5 mm (0.2 inches) -- and mixtures of oxidizers and inert gases to learn more about the physics of combustion in the simplest burning configuration, a sphere. The experiment elapsed time is shown at the bottom of the composite image. The DCE principal investigator was Forman Williams, University of California, San Diego. The experiment was part of the space research investigations conducted during the Microgravity Science Laboratory-1R mission (STS-94, July 1-17 1997). Advanced combustion experiments will be a part of investigations plarned for the International Space Station. (121KB JPEG, 654 x 977 pixels; downlinked video, higher quality not available) The MPG from which this composite was made is available at http://mix.msfc.nasa.gov/ABSTRACTS/MSFC-0300169.html.

Unusual behavior in magnesium-copper cluster matter produced by helium droplet mediated deposition.

PubMed

Emery, S B; Xin, Y; Ridge, C J; Buszek, R J; Boatz, J A; Boyle, J M; Little, B K; Lindsay, C M

2015-02-28

We demonstrate the ability to produce core-shell nanoclusters of materials that typically undergo intermetallic reactions using helium droplet mediated deposition. Composite structures of magnesium and copper were produced by sequential condensation of metal vapors inside the 0.4 K helium droplet baths and then gently deposited onto a substrate for analysis. Upon deposition, the individual clusters, with diameters ∼5 nm, form a cluster material which was subsequently characterized using scanning and transmission electron microscopies. Results of this analysis reveal the following about the deposited cluster material: it is in the un-alloyed chemical state, it maintains a stable core-shell 5 nm structure at sub-monolayer quantities, and it aggregates into unreacted structures of ∼75 nm during further deposition. Surprisingly, high angle annular dark field scanning transmission electron microscopy images revealed that the copper appears to displace the magnesium at the core of the composite cluster despite magnesium being the initially condensed species within the droplet. This phenomenon was studied further using preliminary density functional theory which revealed that copper atoms, when added sequentially to magnesium clusters, penetrate into the magnesium cores.

Rheological investigation of self-emulsification process.

PubMed

Biradar, Shailesh V; Dhumal, Ravindra S; Paradkar, Anant

2009-01-01

Aim of this study is to investigate the mechanism of self-emulsification through rheological analysis of intermediate liquid crystalline (LC) phase formed during self-emulsification process. Binary system of tween 80 (T80) and imwitor 742 (I742) was used and different SES were prepared with I742 at 10, 30, 50, 70 and 90% w/w concentration levels. Self-emulsification was monitored by visual observations and droplet size measurement. Mesophases obtained by 50% v/v hydration of SES were utilized for polarizing microscopy, differential scanning calorimetry and rheological studies. Good emulsification with nano sized droplets was observed for SES 30% as compared to micron sized droplets for other SES. In polarizing microscopy, formation of intermediate LC phase was observed in all SES. Lamellar phase was evident in 30% SES while other SES exhibited micellar cubic phase. Presence of high level of structurally bound water in thermal analysis confirmed mesophase formation in all SES. In frequency sweep, decrease in elastic modulus, and an increase in phase degree and loss tangent was observed for 30% SES. Exactly opposite trend was seen in other SES. Thus, rheological studies concluded presence of weak and fragile mesophase structure in 30% SES while LC phase structure with little structural buildup was observed in other SES. This weak mesosphere structure in SES 30% presented no or very little resistance against strain induced deformation. Therefore, during emulsification, weak mesophase in SES 30% ruptured with ease and released jet of nanosize droplets compared to coarse droplets for other SES. This study signifies the effect of viscoelastic properties of intermediate LC phase on self-emulsification performance.

Wettability Patterning for Enhanced Dropwise Condensation

NASA Astrophysics Data System (ADS)

Ghosh, Aritra; Ganguly, Ranjan; Megaridis, Constantine

2014-11-01

Dropwise condensation (DwC), in order to be sustainable, requires removal of the condensate droplets. This removal is frequently facilitated by gravity. The rate of DwC heat transfer depends strongly on the maximum departing droplet diameter. Based on wettability patterning, we present a facile technique designed to control the maximum droplet size in DwC within vapor/air atmospheres, and demonstrate how this approach can be used to enhance the corresponding heat transfer rate. We examine various hydrophilic-superhydrophilic patterns, which, respectively sustain DwC and filmwise (FwC) condensation on the substrate. The fabrication method does notemploy any hydrophobizing agent. By juxtaposing parallel lines of hydrophilic (CA ~ 78°) and superhydrophilic (CA ~ 0°) regions on the condensing surface, we create alternating domains of DwC and FwC. The average droplet size on the DwC domain is reduced by ~ 60% compared to the theoretical maximum, which corresponds to the line width. We compare heat transfer rate between unpatternend DwC surfaces and patterned DwC surfaces. Even after sacrificing 40% of condensing area, we achieve up to 20% improvement in condensate collection rate using an interdigitated superhydrophilic pattern, inspired by the vein network of plant leaves. The bioinspired interdigitated pattern is found to outperform the straight hydrophilic-superhydrophilic pattern, particularly under higher vapor loadings in an air/vapor ambient atmosphere. NSF STTR Grant 1331817 via NBD Nano.

Synthesis of hierarchical Mg-doped Fe3O4 micro/nano materials for the decomposition of hexachlorobenzene.

PubMed

Su, Guijin; Liu, Yexuan; Huang, Linyan; Lu, Huijie; Liu, Sha; Li, Liewu; Zheng, Minghui

2014-03-01

An ethylene-glycol (EG) mediated self-assembly process was firstly developed to synthesize micrometer-sized nanostructured Mg-doped Fe3O4 composite oxides to decompose hexachlorobenzene (HCB) at 300°C. The synthesized samples were characterized by scanning electron microscopy, transmission electron microscopy, X-ray diffraction, energy dispersive X-ray spectroscopy and inductively coupled plasma optical emission spectrometer. The morphology and composition of the composite oxide precursor were regulated by the molar ratio of the magnesium acetate and ferric nitrate as the reactants. Calcination of the precursor particles, prepared with different molar ratio of the metal salts, under a reducing nitrogen atmosphere, generated three kinds of Mg doped Fe3O4 composite oxide micro/nano materials. Their reactivity toward HCB decomposition was likely influenced by the material morphology and content of Mg dopants. Ball-like MgFe2O4-Fe3O4 composite oxide micro/nano material showed superior HCB dechlorination efficiencies when compared with pure Fe3O4 micro/nano material, prepared under similar experimental conditions, thus highlighting the benefits of doping Mg into Fe3O4 matrices. Copyright © 2013 Elsevier Ltd. All rights reserved.

The global impact of mineral dust on cloud droplet number concentration

NASA Astrophysics Data System (ADS)

Karydis, V.; Tsimpidi, A.; Bacer, S.; Pozzer, A.; Nenes, A.; Lelieveld, J.

2016-12-01

This study assesses the importance of mineral dust for cloud droplet formation by taking into account i) the adsorption of water on the surface of insoluble dust particles, ii) the coating of soluble material on the surface of mineral particles which augments their cloud condensation nuclei activity, and iii) the effect of dust on the inorganic aerosol concentrations through thermodynamic interactions with mineral cations. Simulations are carried out with the EMAC chemistry climate model that calculates the global atmospheric aerosol composition using the ISORROPIA-II thermodynamic equilibrium model and considers the gas phase interactions with K+-Ca2+-Mg2+-NH4+-Na+-SO42-NO3-Cl-H2O particle components. Emissions of the inert mineral dust and the reactive dust aerosol components are calculated online by taking into account the soil particle size distribution and chemical composition of different deserts worldwide (Karydis et al., 2016). We have implemented the "unified dust activation parameterization" (Kumar et al., 2011; Karydis et al., 2011) to calculate the droplet number concentration by taking into account the inherent hydrophilicity from adsorption and the acquired hygroscopicity from soluble salts by dust particles. Our simulations suggest that mineral dust significantly increases the cloud droplet number concentration (CDNC) over the main deserts and the adjacent oceans. However, over polluted areas the CDNC decreases significantly in the presence of dust. Furthermore, we investigate the role of adsorption activation of insoluble aerosols and the mineral dust thermodynamic interactions with inorganic anions on the cloud droplet formation. The CDNC sensitivity to the emission load, chemical composition, and inherent hydrophilicity of mineral dust is also tested. ReferencesKarydis, et al. (2011). "On the effect of dust particles on global cloud condensation nuclei and cloud droplet number." J. Geophys. Res. Atmos. 116. Karydis, et al. (2016). "Effects of mineral dust on global atmospheric nitrate concentrations." Atmos. Chem. Phys. 16(3): 1491-1509. Kumar, et al. (2011). "Measurements of cloud condensation nuclei activity and droplet activation kinetics of wet processed regional dust samples and minerals." Atmos. Chem. Phys. Discuss. 11(4): 12561-12605.

Self-sensing and thermal energy experimental characterization of multifunctional cement-matrix composites with carbon nano-inclusions

NASA Astrophysics Data System (ADS)

D'Alessandro, A.; Pisello, A. L.; Sambuco, Sara; Ubertini, F.; Asdrubali, F.; Materazzi, A. L.; Cotana, F.

2016-04-01

The recent progress of Nanotechnology allowed the development of new smart materials in several fields of engineering. In particular, innovative construction materials with multifunctional enhanced properties can be produced. The paper presents an experimental characterization on cement-matrix pastes doped with Carbon Nanotubes, Carbon Nano-fibers, Carbon Black and Graphene Nano-platelets. Both electro-mechanical and thermo-physical investigations have been carried out. The conductive nano-inclusions provide the cementitious matrix with piezo-resistive properties allowing the detection of external strain and stress changes. Thereby, traditional building materials, such as concrete and cementitious materials in general, would be capable of self-monitoring the state of deformation they are subject to, giving rise to diffuse sensing systems of structural integrity. Besides supplying self-sensing abilities, carbon nano-fillers may change mechanical, physical and thermal properties of cementitious composites. The experimental tests of the research have been mainly concentrated on the thermal conductivity and the optical properties of the different nano-modified materials, in order to make a critical comparison between them. The aim of the work is the characterization of an innovative multifunctional composite capable of combining self-monitoring properties with proper mechanical and thermal-energy efficiency characteristics. The potential applications of these nano-modified materials cover a wide range of possibilities, such as structural elements, floors, geothermal piles, radiant systems and more.

Scavenging processes of marine aerosols by sea fog over the northern North Pacific

NASA Astrophysics Data System (ADS)

Narita, Y.; Iwamoto, Y.; Yoshida, K.; Kondo, M.; Uematsu, M.

2007-12-01

Sea fog appears frequently over the subarctic North Pacific in summertime. Typical advection fog over this region may affect the distribution of natural and anthropogenic substances from lands as well as marine biogenic substances. To clarify the variation of chemical composition in fog water, size distribution of fog droplets and fog scavenging processes, investigation was conducted over the northern North Pacific, where sea fog appears frequently in summer, during the KH-04-3 cruise of R/V Hakuho-maru in 2004. The sea salt composition is governed 65% of total concentration of inorganic ions and the non-sea-salt (nss-) sulfate occupied 10 % in the 90 sea fog water samples. The average size distribution of liquid water content (LWC) of sea fog showed a bimodal pattern with peaks of 7.0 and 27.5 μm in diameter, while its distribution on land fog commonly showed a monomodal pattern. LWC, number concentrations of fog droplets and concentrations of sea salt composition were high at the edge of the fog area, and decreased toward the center of the fog area. The peak of LWC size distribution was shifted from 17.0 μm at the edge to 36.5 μm in the center area. Based on the relationship of chemical compositions between aerosols and fog droplets, nss-SO42- and NH 4 + in sea fog water consisted of 85 % of the coarse mode aerosol and 15 % of the fine mode by ion basis. The fog droplets are expected to deposit with growing of its droplet size with coagulation and adsorbing reactive gases as a function of the distance from the edge of the sea fog area. These results suggest that sea fog over the subarctic North Pacific is an important as a scavenger of natural and anthropogenic substances transported from the Asian continent and its nitrogen flux to the marine environment may stimulate phytoplankton growth.

Mechanical Behavior of Polymer Nano Bio Composite for Orthopedic Implants

NASA Astrophysics Data System (ADS)

Marimuthu, K., Dr.; Rajan, Sankar

2018-04-01

The bio-based polymer composites have been the focus of many scientific and research projects, as well as many commercial programs. In recent years, scientists and engineers have been working together to use the inherent strength and performance of the new class of bio-based composites which is compactable with human body and can act as a substitute for living cells. In this stage the polymer composites also stepped into human bone implants as a replacement for metallic implants which was problems like corrosion resistance and high cost. The polymer composite have the advantage that it can be molded to the required shape, the polymers have high corrosion resistance, less weight and low cost. The aim of this research is to develop and analyze the suitable bio compactable polymer composite for human implants. The nano particles reinforced polymer composites provides good mechanical properties and shows good tribological properties especially in the total hip and knee replacements. The graphene oxide powders are bio compactable and acts as anti biotic. GO nano powder where reinforced into High-density polyethylene in various weight percentage of 0.5% to 2%. The performance of GO nano powder shows better tribological properties. The material produced does not cause any pollution to the environment and at the same time it can be bio compactable and sustainable. The product will act environmentally friendly.

Physics-Based Simulation and Experiment on Blast Protection of Infill Walls and Sandwich Composites Using New Generation of Nano Particle Reinforced Materials

NASA Astrophysics Data System (ADS)

Irshidat, Mohammad

A critical issue for the development of nanotechnology is our ability to understand, model, and simulate the behavior of small structures and to make the connection between nano structure properties and their macroscopic functions. Material modeling and simulation helps to understand the process, to set the objectives that could guide laboratory efforts, and to control material structures, properties, and processes at physical implementation. These capabilities are vital to engineering design at the component and systems level. In this research, experimental-computational-analytical program was employed to investigate the performance of the new generation of polymeric nano-composite materials, like nano-particle reinforced elastomeric materials (NPREM), for the protection of masonry structures against blast loads. New design tools for using these kinds of materials to protect Infill Walls (e.g. masonry walls) against blast loading were established. These tools were also extended to cover other type of panels like sandwich composites. This investigation revealed that polymeric nano composite materials are strain rate sensitive and have large amount of voids distributed randomly inside the materials. Results from blast experiments showed increase in ultimate flexural resistance achieved by both unreinforced and nano reinforced polyurea retrofit systems applied to infill masonry walls. It was also observed that a thin elastomeric coating on the interior face of the walls could be effective at minimizing the fragmentation resulting from blast. More conclusions are provided with recommended future research.

Mechanical and thermal properties and morphological studies of 10 MeV electron beam irradiated LDPE/hydroxyapatite nano-composite

NASA Astrophysics Data System (ADS)

Soltani, Z.; Ziaie, F.; Ghaffari, M.; Afarideh, H.; Ehsani, M.

2013-02-01

In this work the nano-composite samples were prepared using the LDPE filled with different weight percentages of hydroxyapatite powder which was synthesized via hydrolysis method. The samples were subjected to irradiation under 10 MeV electron beam in 75-250 kGy doses. Mechanical and thermal properties as well as the morphology of the nano-composite samples were investigated and compared. The hot-set and swelling tests confirmed the radiation crosslinking induced in the polymer matrix especially between the matrix and reinforcement phase. The result indicates that the mechanical and thermal parameters are strongly dependent on the hydroxyapatite content in comparison to radiation.

Mechanically Stretchable and Electrically Insulating Thermal Elastomer Composite by Liquid Alloy Droplet Embedment.

PubMed

Jeong, Seung Hee; Chen, Si; Huo, Jinxing; Gamstedt, Erik Kristofer; Liu, Johan; Zhang, Shi-Li; Zhang, Zhi-Bin; Hjort, Klas; Wu, Zhigang

2015-12-16

Stretchable electronics and soft robotics have shown unsurpassed features, inheriting remarkable functions from stretchable and soft materials. Electrically conductive and mechanically stretchable materials based on composites have been widely studied for stretchable electronics as electrical conductors using various combinations of materials. However, thermally tunable and stretchable materials, which have high potential in soft and stretchable thermal devices as interface or packaging materials, have not been sufficiently studied. Here, a mechanically stretchable and electrically insulating thermal elastomer composite is demonstrated, which can be easily processed for device fabrication. A liquid alloy is embedded as liquid droplet fillers in an elastomer matrix to achieve softness and stretchability. This new elastomer composite is expected useful to enhance thermal response or efficiency of soft and stretchable thermal devices or systems. The thermal elastomer composites demonstrate advantages such as thermal interface and packaging layers with thermal shrink films in transient and steady-state cases and a stretchable temperature sensor.

Free energy of formation of a crystal nucleus in incongruent solidification: Implication for modeling the crystallization of aqueous nitric acid droplets in polar stratospheric clouds

NASA Astrophysics Data System (ADS)

Djikaev, Yuri S.; Ruckenstein, Eli

2017-04-01

Using the formalism of classical thermodynamics in the framework of the classical nucleation theory, we derive an expression for the reversible work W* of formation of a binary crystal nucleus in a liquid binary solution of non-stoichiometric composition (incongruent crystallization). Applied to the crystallization of aqueous nitric acid droplets, the new expression more adequately takes account of the effects of nitric acid vapor compared to the conventional expression of MacKenzie, Kulmala, Laaksonen, and Vesala (MKLV) [J. Geophys. Res.: Atmos. 102, 19729 (1997)]. The predictions of both MKLV and modified expressions for the average liquid-solid interfacial tension σls of nitric acid dihydrate (NAD) crystals are compared by using existing experimental data on the incongruent crystallization of aqueous nitric acid droplets of composition relevant to polar stratospheric clouds (PSCs). The predictions for σls based on the MKLV expression are higher by about 5% compared to predictions based on our modified expression. This results in similar differences between the predictions of both expressions for the solid-vapor interfacial tension σsv of NAD crystal nuclei. The latter can be obtained by using the method based on the analysis of experimental data on crystal nucleation rates in aqueous nitric acid droplets; it exploits the dominance of the surface-stimulated mode of crystal nucleation in small droplets and its negligibility in large ones. Applying that method to existing experimental data, our expression for the free energy of formation provides an estimate for σsv of NAD in the range ≈92 dyn/cm to ≈100 dyn/cm, while the MKLV expression predicts it in the range ≈95 dyn/cm to ≈105 dyn/cm. The predictions of both expressions for W* become identical for the case of congruent crystallization; this was also demonstrated by applying our method for determining σsv to the nucleation of nitric acid trihydrate crystals in PSC droplets of stoichiometric composition.

Combining Hard with Soft Materials in Nanoscale Under High-Pressure High-Temperature Conditions

NASA Technical Reports Server (NTRS)

Palosz, B.; Gierlotka, S.; Swiderska-Sroda, A.; Fietkiewicz, K.; Kalisz, G.; Grzanka, E.; Stel'makh, S.; Palosz, W.

2004-01-01

Nano-composites with a primary nanocrystalline ceramic matrix and a secondary nanocrystalline material (metal or semiconductor) were synthesized by infiltration of an appropriate liquid into ceramic compacts under pressures of up to 8 GPa and temperatures of up to 2000 K. The purpose of our work is to obtain nanocomposites which constitute homoger?ous mixtures of two phases, both forming nano- grains of about 10 nm in size. The high pressure is used to bring the porosity of the compacted powders down to the nano-scale and force a given liquid into the nano-sized pores. The advantage of the infiltration technique is that, in a single, continuous process, we start with a nanocrystalline powder, compress it to form the matrix of the composite, and crystallize and/or synthesize a second nanomaterial in the matrix pores. The key limitation of this technology is, that the pores in the matrix need to stay open during the entire process of infiltration. Thus the initial powder should form a rigid skeleton, otherwise the so-called self-stop process can limit cr block a further flow of the liquid phase and hinder the process of the composite formation. Therefore powders of only very hard ceramic materials like diamond, Sic, or Alz03, which can withstand a substantial external load without undesired deformation, can be used as the primary phase. With this technique, using diamond and S i c ceramic powders infiltrated by liquid metals (AI, Zn, Sn, Ag, Au) and semiconductors (Si, Ge, GaAs, CdTe), we obtained nano-composites with the grain size in the range of 10 - 30 nm. Our work addresses the key problem in manufacturing bulk nanocrystalline materials, i.e. preservation of nano-scale during the fabrication process. In this paper we discuss basic technical and methodological problems associated with nano-infiltration based on the results obtained for Zn-Sic composites.

Gold surface supported spherical liposome-gold nano-particle nano-composite for label free DNA sensing.

PubMed

Bhuvana, M; Narayanan, J Shankara; Dharuman, V; Teng, W; Hahn, J H; Jayakumar, K

2013-03-15

Immobilization of 1,2-dioleoyl-sn-glycero-3-phosphoethanolamine (DOPE) liposome-gold nano-particle (DOPE-AuNP) nano-composite covalently on 3-mercaptopropionic acid (MPA) on gold surface is demonstrated for the first time for electrochemical label free DNA sensing. Spherical nature of the DOPE on the MPA monolayer is confirmed by the appearance of sigmoidal voltammetric profile, characteristic behavior of linear diffusion, for the MPA-DOPE in presence of [Fe(CN)(6)](3-/4-) and [Ru(NH(3))(6)](3+) redox probes. The DOPE liposome vesicle fusion is prevented by electroless deposition of AuNP on the hydrophilic amine head groups of the DOPE. Immobilization of single stranded DNA (ssDNA) is made via simple gold-thiol linkage for DNA hybridization sensing in the presence of [Fe(CN)(6)](3-/4-). The sensor discriminates the hybridized (complementary target hybridized), un-hybridized (non-complementary target hybridized) and single base mismatch target hybridized surfaces sensitively and selectively without signal amplification. The lowest target DNA concentration detected is 0.1×10(-12)M. Cyclic voltammetry (CV), electrochemical impedance (EIS), differential pulse voltammetry (DPV) and quartz crystal microbalance (QCM) techniques are used for DNA sensing on DOPE-AuNP nano-composite. Transmission Electron Microscopy (TEM), Fourier Transform Infrared Spectroscopy (FTIR), Atomic Force Microscopy (AFM), Dynamic Light Scattering (DLS) and Ultraviolet-Visible (UV) spectroscopic techniques are used to understand the interactions between the DOPE, AuNP and ssDNA. The results indicate the presence of an intact and well defined spherical DOPE-AuNP nano-composite on the gold surface. The method could be applied for fabrication of the surface based liposome-AuNP-DNA composite for cell transfection studies at reduced reagents and costs. Copyright © 2012 Elsevier B.V. All rights reserved.

Hydrogen storage properties of nano-structural carbon and metal hydrides composites

NASA Astrophysics Data System (ADS)

Miyaoka, Hiroki; Ichikawa, Takayuki; Isobe, Shigehito; Fujii, Hironobu

2006-08-01

Thermodynamic and structural properties of some ball-milled mixtures composed of the hydrogenated nanostructural carbon (C nanoH x) and metal hydride (MH; M=Li, Na, Mg and Ca) were examined from thermal desoroption mass spectroscopy and powder X-ray diffraction, respectively. The results showed that the hydrogen desorption temperatures are significantly lowered from those of each hydride (C nanoH x, MH) in the composites. This indicates that a new type of interaction exists between C nanoH x and MH, which destabilizes C-H and/or M-H bonding as well. Therefore, the above Metal-C-H system would be recognized as a new family of hydrogen storage materials.

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

NASA Astrophysics Data System (ADS)

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

2018-04-01

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

Dynamically reconfigurable complex emulsions via tunable interfacial tensions.

PubMed

Zarzar, Lauren D; Sresht, Vishnu; Sletten, Ellen M; Kalow, Julia A; Blankschtein, Daniel; Swager, Timothy M

2015-02-26

Emulsification is a powerful, well-known technique for mixing and dispersing immiscible components within a continuous liquid phase. Consequently, emulsions are central components of medicine, food and performance materials. Complex emulsions, including Janus droplets (that is, droplets with faces of differing chemistries) and multiple emulsions, are of increasing importance in pharmaceuticals and medical diagnostics, in the fabrication of microparticles and capsules for food, in chemical separations, in cosmetics, and in dynamic optics. Because complex emulsion properties and functions are related to the droplet geometry and composition, the development of rapid, simple fabrication approaches allowing precise control over the droplets' physical and chemical characteristics is critical. Significant advances in the fabrication of complex emulsions have been made using a number of procedures, ranging from large-scale, less precise techniques that give compositional heterogeneity using high-shear mixers and membranes, to small-volume but more precise microfluidic methods. However, such approaches have yet to create droplet morphologies that can be controllably altered after emulsification. Reconfigurable complex liquids potentially have great utility as dynamically tunable materials. Here we describe an approach to the one-step fabrication of three- and four-phase complex emulsions with highly controllable and reconfigurable morphologies. The fabrication makes use of the temperature-sensitive miscibility of hydrocarbon, silicone and fluorocarbon liquids, and is applied to both the microfluidic and the scalable batch production of complex droplets. We demonstrate that droplet geometries can be alternated between encapsulated and Janus configurations by varying the interfacial tensions using hydrocarbon and fluorinated surfactants including stimuli-responsive and cleavable surfactants. This yields a generalizable strategy for the fabrication of multiphase emulsions with controllably reconfigurable morphologies and the potential to create a wide range of responsive materials.

Dynamically reconfigurable complex emulsions via tunable interfacial tensions

NASA Astrophysics Data System (ADS)

Zarzar, Lauren D.; Sresht, Vishnu; Sletten, Ellen M.; Kalow, Julia A.; Blankschtein, Daniel; Swager, Timothy M.

2015-02-01

Emulsification is a powerful, well-known technique for mixing and dispersing immiscible components within a continuous liquid phase. Consequently, emulsions are central components of medicine, food and performance materials. Complex emulsions, including Janus droplets (that is, droplets with faces of differing chemistries) and multiple emulsions, are of increasing importance in pharmaceuticals and medical diagnostics, in the fabrication of microparticles and capsules for food, in chemical separations, in cosmetics, and in dynamic optics. Because complex emulsion properties and functions are related to the droplet geometry and composition, the development of rapid, simple fabrication approaches allowing precise control over the droplets' physical and chemical characteristics is critical. Significant advances in the fabrication of complex emulsions have been made using a number of procedures, ranging from large-scale, less precise techniques that give compositional heterogeneity using high-shear mixers and membranes, to small-volume but more precise microfluidic methods. However, such approaches have yet to create droplet morphologies that can be controllably altered after emulsification. Reconfigurable complex liquids potentially have great utility as dynamically tunable materials. Here we describe an approach to the one-step fabrication of three- and four-phase complex emulsions with highly controllable and reconfigurable morphologies. The fabrication makes use of the temperature-sensitive miscibility of hydrocarbon, silicone and fluorocarbon liquids, and is applied to both the microfluidic and the scalable batch production of complex droplets. We demonstrate that droplet geometries can be alternated between encapsulated and Janus configurations by varying the interfacial tensions using hydrocarbon and fluorinated surfactants including stimuli-responsive and cleavable surfactants. This yields a generalizable strategy for the fabrication of multiphase emulsions with controllably reconfigurable morphologies and the potential to create a wide range of responsive materials.

Three-factor response surface optimization of nano-emulsion formation using a microfluidizer.

PubMed

Sadeghpour Galooyak, Saeed; Dabir, Bahram

2015-05-01

Emulsification of sunflower oil in water by microfluidization was studied. Response surface methodology (RSM) and the central composite design (CCD) were applied to determine the effects of certain process parameters on performance of the apparatus for optimization of nano-emulsion fabrication. Influence of pressure, oil content and number of passes on the disruption of emulsions was studied. Quadratic multiple regression models were chosen for two available responses, namely Sauter mean diameter (SMD) and Polydispersity index (PdI). Analysis of variance (ANOVA) showed a high coefficient of determination (R(2)) value for both responses, confirming adjustment of the models with experimental data. The SMD and the PdI decreased as the pressure of emulsification increased from 408 to 762.3 bar for the oil content of 5 vol% and from 408 to 854.4 bar for the oil content of 13 vol%, and thereafter, increasing the pressure up to 952 bar led to increasing the both responses. The results implied that laminar elongational flow is the alternative disruption mechanism in addition to inertia in turbulence flow, especially at low treatment pressures. Both of responses improved with increase in number of passes from 2 to 4 cycles. The oil content depicted low effect on responses; however, interaction of this parameter with other regressors pointed remarkable impact. Also, the effect of pressure on Kolmogorov micro-scale was studied. The results implied that Kolmogorov equation did not take into account the over-processing and was applicable only for disruption of droplets in the inertial turbulent flow.

Microstructure and properties of Cu-Sn-Zn-TiO 2 nano-composite coatings on mild steel

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

Gao, Weidong; Cao, Di; Jin, Yunxue

Cu-Sn-Zn coatings have been widely used in industry for their unique properties, such as good conductivity, high corrosion resistance and excellent solderability. To further improve the mechanical performance of Cu-Sn-Zn coatings, powder-enhanced method was applied and Cu-Sn-Zn-TiO 2 nano-composite coatings with different TiO 2 concentration were fabricated. The microstructure of Cu-Sn-Zn-TiO 2 nano-composite coatings were investigated by X-ray diffraction (XRD) and Scanning Electron Microscopy (SEM). The mechanical properties of coatings including microhardness and wear resistance were studied. The results indicate that the incorporation of TiO 2 nanoparticle can significantly influence the properties of Cu-Sn-Zn coatings. The microhardness of Cu-Sn-Zn coatingmore » was increased to 383 HV from 330 HV with 1 g/L TiO 2 addition. Also, the corrosion resistance of coating was enhanced. The effects of TiO 2 nanoparticle concentration on the microstructure, mechanical properties and corrosion resistance of Cu-Sn-Zn-TiO 2 nano-composite coatings were discussed.« less

Microstructure and properties of Cu-Sn-Zn-TiO 2 nano-composite coatings on mild steel

DOE PAGES

Gao, Weidong; Cao, Di; Jin, Yunxue; ...

2018-04-18

Cu-Sn-Zn coatings have been widely used in industry for their unique properties, such as good conductivity, high corrosion resistance and excellent solderability. To further improve the mechanical performance of Cu-Sn-Zn coatings, powder-enhanced method was applied and Cu-Sn-Zn-TiO 2 nano-composite coatings with different TiO 2 concentration were fabricated. The microstructure of Cu-Sn-Zn-TiO 2 nano-composite coatings were investigated by X-ray diffraction (XRD) and Scanning Electron Microscopy (SEM). The mechanical properties of coatings including microhardness and wear resistance were studied. The results indicate that the incorporation of TiO 2 nanoparticle can significantly influence the properties of Cu-Sn-Zn coatings. The microhardness of Cu-Sn-Zn coatingmore » was increased to 383 HV from 330 HV with 1 g/L TiO 2 addition. Also, the corrosion resistance of coating was enhanced. The effects of TiO 2 nanoparticle concentration on the microstructure, mechanical properties and corrosion resistance of Cu-Sn-Zn-TiO 2 nano-composite coatings were discussed.« less

Marginal and internal fit of nano-composite CAD/CAM restorations.

PubMed

Park, So-Hyun; Yoo, Yeon-Jee; Shin, Yoo-Jin; Cho, Byeong-Hoon; Baek, Seung-Ho

2016-02-01

The purpose of this study was to compare the marginal and internal fit of nano-composite CAD-CAM restorations. A full veneer crown and an mesio-occluso-distal (MOD) inlay cavity, which were prepared on extracted human molars, were used as templates of epoxy resin replicas. The prepared teeth were scanned and CAD-CAM restorations were milled using Lava Ultimate (LU) and experimental nano-composite CAD/CAM blocks (EB) under the same milling parameters. To assess the marginal and internal fit, the restorations were cemented to replicas and were embedded in an acrylic mold for sectioning at 0.5 mm intervals. The measured gap data were pooled according to the block types and measuring points for statistical analysis. Both the block type and measuring point significantly affected gap values, and their interaction was significant (p = 0.000). In crowns and inlays made from the two blocks, gap values were significantly larger in the occlusal area than in the axial area, while gap values in the marginal area were smallest (p < 0.001). Among the blocks, the restorations milled from EB had a significantly larger gap at all measuring points than those milled from LU (p = 0.000). The marginal and internal gaps of the two nano-composite CAD/CAM blocks differed according to the measuring points. Among the internal area of the two nano-composite CAD/CAM restorations, occlusal gap data were significantly larger than axial gap data. The EB crowns and inlays had significantly larger gaps than LU restorations.

In Vitro Wear Resistance of Nano-Hybrid Composite Denture Teeth.

PubMed

Munshi, Nabeel; Rosenblum, Marc; Jiang, Shuying; Flinton, Robert

2017-04-01

To evaluate the wear resistance of nano-hybrid composite denture teeth as compared to two commonly used denture teeth: interpenetrating polymer network (IPN) and double crosslinking polymethylmethacrylate (PMMA) denture teeth. 18 styli and 18 disk specimens were prepared from the three denture tooth materials: nano-hybrid composite, IPN, and double crosslinking PMMA. The specimens were mounted in a two-body wear testing machine to simulate chewing in the complete denture. The amount of wear from the styli specimens were measured before and after using a digital micrometer, and the depth of the wear track from the disk specimens was measured using a noncontact 3D optical profilometer. The total wear from each denture tooth group was compared using one-way ANOVA with a 0.05 significance level. A Tukey post hoc test was used to determine differences between the three groups. The mean total wear in the nano-hybrid composite teeth group was 1.16 mm, SD = 0.5 mm, statistically significantly higher (p ≤ 0.0001) than the IPN (mean = 0.13 mm, SD = 0.05) and double crosslinking PMMA tooth groups (mean = 0.31 mm, SD = 0.19). There was no statistically significant difference between IPN denture teeth and double crosslinking PMMA denture teeth in the amount of wear. Nano-hybrid composite denture teeth exhibited statistically significantly more wear than the IPN and double crosslinking PMMA denture teeth. © 2015 by the American College of Prosthodontists.

An Overview of Lipid Droplets in Cancer and Cancer Stem Cells

PubMed Central

Seco, J.

2017-01-01

For decades, lipid droplets have been considered as the main cellular organelles involved in the fat storage, because of their lipid composition. However, in recent years, some new and totally unexpected roles have been discovered for them: (i) they are active sites for synthesis and storage of inflammatory mediators, and (ii) they are key players in cancer cells and tissues, especially in cancer stem cells. In this review, we summarize the main concepts related to the lipid droplet structure and function and their involvement in inflammatory and cancer processes. PMID:28883835

Finite Element Model Characterization Of Nano-Composite Thermal And Environmental Barrier Coatings

NASA Technical Reports Server (NTRS)

Yamada, Yoshiki; Zhu, Dongming

2011-01-01

Thermal and environmental barrier coatings have been applied for protecting Si based ceramic matrix composite components from high temperature environment in advanced gas turbine engines. It has been found that the delamination and lifetime of T/EBC systems generally depend on the initiation and propagation of surface cracks induced by the axial mechanical load in addition to severe thermal loads. In order to prevent T/EBC systems from surface cracking and subsequent delamination due to mechanical and thermal stresses, T/EBC systems reinforced with nano-composite architectures have showed promise to improve mechanical properties and provide a potential crack shielding mechanism such as crack bridging. In this study, a finite element model (FEM) was established to understand the potential beneficial effects of nano-composites systems such as SiC nanotube-reinforced oxide T/EBC systems.

Composite materials formed with anchored nanostructures

DOEpatents

Seals, Roland D; Menchhofer, Paul A; Howe, Jane Y; Wang, Wei

2015-03-10

A method of forming nano-structure composite materials that have a binder material and a nanostructure fiber material is described. A precursor material may be formed using a mixture of at least one metal powder and anchored nanostructure materials. The metal powder mixture may be (a) Ni powder and (b) NiAl powder. The anchored nanostructure materials may comprise (i) NiAl powder as a support material and (ii) carbon nanotubes attached to nanoparticles adjacent to a surface of the support material. The process of forming nano-structure composite materials typically involves sintering the mixture under vacuum in a die. When Ni and NiAl are used in the metal powder mixture Ni.sub.3Al may form as the binder material after sintering. The mixture is sintered until it consolidates to form the nano-structure composite material.

Color Composite Image of the Supernova Remnant

NASA Technical Reports Server (NTRS)

2000-01-01

This image is a color composite of the supernova remnant E0102-72: x-ray (blue), optical (green), and radio (red). E0102-72 is the remnant of a star that exploded in a nearby galaxy known as the Small Magellanic Cloud. The star exploded outward at speeds in excess of 20 million kilometers per hour (12 million mph) and collided with surrounding gas. This collision produced two shock waves, or cosmic sonic booms, one traveling outward, and the other rebounding back into the material ejected by the explosion. The radio image, shown in red, was made using the Australia Telescope Compact Array. The radio waves are due to extremely high-energy electrons spiraling around magnetic field lines in the gas and trace the outward moving shock wave. The Chandra X-ray Observatory image, shown in blue, shows gas that has been heated to millions of degrees by the rebounding, or reverse shock wave. The x-ray data show that this gas is rich in oxygen and neon. These elements were created by nuclear reactions inside the star and hurled into space by the supernova. The Hubble Space Telescope optical image, shown in green, shows dense clumps of oxygen gas that have 'cooled' to about 30,000 degrees. Photo Credit: X-ray (NASA/CXC/SAO); optical (NASA/HST): radio: (ACTA)

Strategy to Minimize Energetics Contamination at Military Testing/Training Ranges

DTIC Science & Technology

2005-09-01

exploding foil exploding foil initiator ) initiator will minimize the energetic material...i.e., exploding foil initiator P 𔃾 𔃾 𔃾 𔃾 4. Use an electronic S&A; i.e., high voltage driven semi-conductor bridge elements P ’ 𔃾 𔃾 𔃾 5. Use...alternatives Opportunity 1. Eliminate energetics 3. Use an electronic S&A; i.e., exploding foil initiator 1 3 3 -3 2 -6 -2 1 -2 -5 4. Use an

Ternary liquid mixtures control the multiplicity, shape and internal structure of emulsion droplets

NASA Astrophysics Data System (ADS)

Haase, Martin F.; Brujic, Jasna

2014-03-01

It is important to control the shape, internal structure and stability of emulsion droplets for drug delivery, biochemical assays, and the design of materials with novel physical properties. Successful methods involve the mechanical manipulation of the flow of oil in water using complex microfluidic devices to make multiple emulsions with a sequential introduction of specific reactants. Instead, here we show how the thermodynamics of immiscible liquid mixtures tailor emulsions using a single dripping instability. For example, the initial composition and choice of surfactant govern the multiplicity of concentric alternating oil and water layers inside the droplets. Stabilizing ternary droplets using nanoparticles gives rise to a plethora of shapes whose geometry is defined by the deformability of the shell and the flow rate. Another option is to incorporate lipids to the multiple emulsion droplet, which form vesicles upon expulsion of the inner water droplets. Depending on the number of initial water droplets, these vesicles eventually form complex hollow topologies, which can be used as junctions or scaffolds for the self-assembly of colloidal particles in the future.

Dielectric Properties of Polyether Sulfone/Bismaleimide Resin Composite Based on Nanolumina Modified by Super-Critical Ethanol

NASA Astrophysics Data System (ADS)

Chen, Yufei; Li, Zhichao; Teng, Chengjun; Li, Fangliang; Han, Yang

2016-11-01

Nano-alumina was chemically modified with super-critical ethanol enabling a surface active coating. Modified nano-alumina was incorporated in polymer blends based on thermoplastic polyether sulfone and thermosetting bismaleimide resin to produce novel nanocomposites designated as SCE-Al2O3/PES-MBAE. In the SCE-Al2O3/PES-MBAE nano-composites, the matrix was originally formed from 4,4'-diamino diphenyl methane bismaleimide (MBMI) using the diluents of 3,3'-diallyl bisphenol A (BBA) and bisphenol-A diallyl ether (BBE), while polyether sulfone (PES) was used as toughening agent along with super-critically modified nano-alumina (SCE-Al2O3) as filler material. The content of SCE-Al2O3 was varied from 0 wt.% to 6 wt.%. The nano-composites were characterized for their morphological, spectroscopic and dielectric properties. Fourier transform infrared spectroscopy (FT-IR) indicated that ethanol molecules had adhered to the surface of the nano-Al2O3 in super-critical state. A reaction between MBMI and allyl compound occurred and SCE-Al2O3 was doped into the polymer matrix. Volume resistivity of the composite initially increased and then decreased. The modification due to SCE-Al2O3 could overcome the undesirable impact of PES by using a bare minimum level of SCE-Al2O3. The dielectric constant ( ɛ) and dielectric loss (tan δ) as in the case of volume resistivity were initially increased and then decreased with the content of SCE-Al2O3 in the composite. The dielectric constant, dielectric loss and dielectric strength of SCE-Al2O3 (4 wt.%)/PES (5 wt.%)-MBAE nano-composite were 3.53 (100 Hz), 1.52 × 10-3 (100 Hz) and 15.66 kV/mm, respectively, which indicated that the dielectric properties of the composite fulfilled the basic requirements of electrical and insulating material. It was evident from the morphological analysis that the SCE-Al2O3 was evenly dispersed at the nanoscale; for example, the size of SCE-Al2O3 in SCE-Al2O3 (4 wt.%)/PES (5 wt.%)-MBAE measured less than 50 nm.

Somewhere in the Rainbow

NASA Technical Reports Server (NTRS)

1998-01-01

Aerometrics, Inc.'s Rainbow Refractometer was developed through an SBIR (Small Business Innovative Research) contract with Lewis Research Center. The system is a non- intrusive instrument for measuring droplet inside of refraction. It can also derive the temperature and chemical composition of refractive droplets. The technology can be integrated with the Phase Doppler Particle Analyzer systems (featured in Spinoff 1994) or used independently.

Electrical current nanogeneration driven by spontaneous nanofluidic oscillations.

PubMed

Gimenez, R; Mercuri, M; Berli, C L A; Bellino, M G

2018-02-15

Exploiting natural phenomena is a central route for providing electricity to sustainably drive wearable electronics. Here we report a nano-scale water-driven energy generator that produces tiny electrical currents from spontaneous wetting-drying oscillations in mesoporous thin films. The system was fabricated with a wormlike mesoporous silica film, which was packed in between Cu and silicon contacts. The nanogenerator runs autonomously when a water droplet is laid over the film close to the Cu electrode, as water infiltration into the film under the electrode produces a direct-current. Wetting-drying cycles, which are spontaneously triggered by water evaporation, are perfectly correlated to the generated electrical current. The autonomous water displacement through the film yields a sustained energy conversion until the droplet reservoir vanishes. This novel water-driven nanogenerator opens new alternatives for versatile, mobile and cost-effective self-powering of nanosystems and nanodevices.

Carbon Cloth Supported Nano-Mg(OH)2 for the Enrichment and Recovery of Rare Earth Element Eu(III) From Aqueous Solution.

PubMed

Li, Yinong; Tian, Chen; Liu, Weizhen; Xu, Si; Xu, Yunyun; Cui, Rongxin; Lin, Zhang

2018-01-01

Nano-Mg(OH) 2 is attracting great attention as adsorbent for pre-concentration and recovery of rare earth elements (REEs) from low-concentration solution, due to its superior removal efficiency for REEs and environmental friendliness. However, the nanoparticles also cause some severe problems during application, including aggregation, blockage in fixed-bed column, as well as the difficulties in separation and reuse. Herein, in order to avoid the mentioned problems, a carbon cloth (CC) supported nano-Mg(OH) 2 (nano-Mg(OH) 2 @CC) was synthesized by electrodeposition. The X-ray diffraction and scanning electron microscopy analysis demonstrated that the interlaced nano-sheet of Mg(OH) 2 grew firmly and uniformly on the surface of carbon cloth fibers. Batch adsorption experiments of Eu(III) indicated that the nano-Mg(OH) 2 @CC composite maintained the excellent adsorption performance of nano-Mg(OH) 2 toward Eu(III). After adsorption, the Eu containing composite was calcined under nitrogen atmosphere. The content of Eu 2 O 3 in the calcined material was as high as 99.66%. Fixed-bed column experiments indicated that no blockage for Mg(OH) 2 @CC composite was observed during the treatment, while the complete blockage of occurred to nano-Mg(OH) 2 at an effluent volume of 240 mL. Moreover, the removal efficiency of Mg(OH) 2 @CC was still higher than 90% until 4,200 mL of effluent volume. This work provides a promising method for feasible application of nanoadsorbents in fixed-bed process to recycle low-concentration REEs from wastewater.

Carbon Cloth Supported Nano-Mg(OH)2 for the Enrichment and Recovery of Rare Earth Element Eu(III) from Aqueous Solution

NASA Astrophysics Data System (ADS)

Li, Yinong; Tian, Chen; Liu, Weizhen; Xu, Si; Xu, Yunyun; Cui, Rongxin; Lin, Zhang

2018-04-01

Nano-Mg(OH)2 is attracting great attention as adsorbent for pre-concentration and recovery of rare earth elements (REEs) from low-concentration solution, due to its superior removal efficiency for REEs and environmental friendliness. However, the nanoparticles also cause some severe problems during application, including aggregation, blockage in fixed-bed column, as well as the difficulties in separation and reuse. Herein, in order to avoid the mentioned problems, a carbon cloth (CC) supported nano-Mg(OH)2 (nano-Mg(OH)2@CC) was synthesized by electrodeposition. The X-ray diffraction and scanning electron microscopy analysis demonstrated that the interlaced nano-sheet of Mg(OH)2 grew firmly and uniformly on the surface of carbon cloth fibers. Batch adsorption experiments of Eu(III) indicated that the nano-Mg(OH)2@CC composite maintained the excellent adsorption performance of nano-Mg(OH)2 toward Eu(III). After adsorption, the Eu containing composite was calcined under nitrogen atmosphere. The content of Eu2O3 in the calcined material was as high as 99.66%. Fixed-bed column experiments indicated that no blockage for Mg(OH)2@CC composite was observed during the treatment, while the complete blockage of occurred to nano-Mg(OH)2 at an effluent volume of 240 mL. Moreover, the removal efficiency of Mg(OH)2@CC was still higher than 90% until 4200 mL of effluent volume. This work provides a promising method for feasible application of nanoadsorbents in fixed-bed process to recycle low-concentration REEs from wastewater.

Carbon Cloth Supported Nano-Mg(OH)2 for the Enrichment and Recovery of Rare Earth Element Eu(III) From Aqueous Solution

PubMed Central

Li, Yinong; Tian, Chen; Liu, Weizhen; Xu, Si; Xu, Yunyun; Cui, Rongxin; Lin, Zhang

2018-01-01

Nano-Mg(OH)2 is attracting great attention as adsorbent for pre-concentration and recovery of rare earth elements (REEs) from low-concentration solution, due to its superior removal efficiency for REEs and environmental friendliness. However, the nanoparticles also cause some severe problems during application, including aggregation, blockage in fixed-bed column, as well as the difficulties in separation and reuse. Herein, in order to avoid the mentioned problems, a carbon cloth (CC) supported nano-Mg(OH)2 (nano-Mg(OH)2@CC) was synthesized by electrodeposition. The X-ray diffraction and scanning electron microscopy analysis demonstrated that the interlaced nano-sheet of Mg(OH)2 grew firmly and uniformly on the surface of carbon cloth fibers. Batch adsorption experiments of Eu(III) indicated that the nano-Mg(OH)2@CC composite maintained the excellent adsorption performance of nano-Mg(OH)2 toward Eu(III). After adsorption, the Eu containing composite was calcined under nitrogen atmosphere. The content of Eu2O3 in the calcined material was as high as 99.66%. Fixed-bed column experiments indicated that no blockage for Mg(OH)2@CC composite was observed during the treatment, while the complete blockage of occurred to nano-Mg(OH)2 at an effluent volume of 240 mL. Moreover, the removal efficiency of Mg(OH)2@CC was still higher than 90% until 4,200 mL of effluent volume. This work provides a promising method for feasible application of nanoadsorbents in fixed-bed process to recycle low-concentration REEs from wastewater. PMID:29721492

High-rate nano-crystalline Li 4Ti 5O 12 attached on carbon nano-fibers for hybrid supercapacitors

NASA Astrophysics Data System (ADS)

Naoi, Katsuhiko; Ishimoto, Shuichi; Isobe, Yusaku; Aoyagi, Shintaro

A lithium titanate (Li 4Ti 5O 12)-based electrode which can operate at unusually high current density (300 C) was developed as negative electrode for hybrid capacitors. The high-rate Li 4Ti 5O 12 electrode has a unique nano-structure consisting of unusually small nano-crystalline Li 4Ti 5O 12 (ca. 5-20 nm) grafted onto carbon nano-fiber anchors (nc-Li 4Ti 5O 12/CNF). This nano-structured nc-Li 4Ti 5O 12/CNF composite are prepared by simple sol-gel method under ultra-centrifugal force (65,000 N) followed by instantaneous annealing at 900 °C for 3 min. A model hybrid capacitor cell consisting of a negative nc-Li 4Ti 5O 12/CNF composite electrode and a positive activated carbon electrode showed high energy density of 40 Wh L -1 and high power density of 7.5 kW L -1 comparable to conventional EDLCs.

Method of preparing copper-dendritic composite alloys for mechanical reduction

DOEpatents

Verhoeven, John D.; Gibson, Edwin D.; Schmidt, Frederick A.; Spitzig, William A.

1988-01-01

Copper-dendritic composite alloys are prepared for mechanical reduction to increase tensile strength by dispersing molten droplets of the composite alloy into an inert gas; solidifying the droplets in the form of minute spheres or platelets; and compacting a mass of the spheres or platelets into an integrated body. The spheres preferably have diameters of from 50 to 2000 .mu.m, and the platelets thicknesses of 100 to 2000 .mu.m. The resulting spheres or platelets will contain ultra-fine dendrites which produce higher strengths on mechanical reduction of the bodies formed therefrom, or comparable strengths at lower reduction values. The method is applicable to alloys of copper with vanadium, niobium, tantalum, chromium, molybdenum, tungsten, iron and cobalt.

Method of preparing copper-dendritic composite alloys for mechanical reduction

DOEpatents

Verhoeven, J.D.; Gibson, E.D.; Schmidt, F.A.; Spitzig, W.A.

1988-09-13

Copper-dendritic composite alloys are prepared for mechanical reduction to increase tensile strength by dispersing molten droplets of the composite alloy into an inert gas; solidifying the droplets in the form of minute spheres or platelets; and compacting a mass of the spheres or platelets into an integrated body. The spheres preferably have diameters of from 50 to 2,000 [mu]m, and the platelets thicknesses of 100 to 2,000 [mu]m. The resulting spheres or platelets will contain ultra-fine dendrites which produce higher strengths on mechanical reduction of the bodies formed therefrom, or comparable strengths at lower reduction values. The method is applicable to alloys of copper with vanadium, niobium, tantalum, chromium, molybdenum, tungsten, iron and cobalt. 3 figs.

Hypersonic Transition Along Curved Surfaces in the Presence of Vortices and Their Control by Using Microtextured Surfaces

DTIC Science & Technology

2015-05-13

Bhagwandin, Pierre N. Floriano, Nico- laos Christodoulides, and John T. McDevitt, “Programmable nano- bio -chip sensors : Analytical meets clinical”, Analytical...superhydrophobic surfaces can be used in many technologies such as self-cleaning coatings for satellite dishes, solar energy panels, photovoltaics and...Design of hydrophobic surfaces for liquid droplet control”, NPG Asia Mater. 3, pp. 49–56 (2011). [15] K. Liu and L. Jiang, “ Bio -inspired self-cleaning

A highly addressable static droplet array enabling digital control of a single droplet at pico-volume resolution.

PubMed

Jeong, Heon-Ho; Lee, Byungjin; Jin, Si Hyung; Jeong, Seong-Geun; Lee, Chang-Soo

2016-04-26

Droplet-based microfluidics enabling exquisite liquid-handling has been developed for diagnosis, drug discovery and quantitative biology. Compartmentalization of samples into a large number of tiny droplets is a great approach to perform multiplex assays and to improve reliability and accuracy using a limited volume of samples. Despite significant advances in microfluidic technology, individual droplet handling in pico-volume resolution is still a challenge in obtaining more efficient and varying multiplex assays. We present a highly addressable static droplet array (SDA) enabling individual digital manipulation of a single droplet using a microvalve system. In a conventional single-layer microvalve system, the number of microvalves required is dictated by the number of operation objects; thus, individual trap-and-release on a large-scale 2D array format is highly challenging. By integrating double-layer microvalves, we achieve a "balloon" valve that preserves the pressure-on state under released pressure; this valve can allow the selective releasing and trapping of 7200 multiplexed pico-droplets using only 1 μL of sample without volume loss. This selectivity and addressability completely arranged only single-cell encapsulated droplets from a mixture of droplet compositions via repetitive selective trapping and releasing. Thus, it will be useful for efficient handling of miniscule volumes of rare or clinical samples in multiplex or combinatory assays, and the selective collection of samples.

Effect of alkali ions (Na+, K+, Cs+) on reaction mechanism of CZTS nano-particles synthesis

NASA Astrophysics Data System (ADS)

Kumar, Suresh; Altosaar, Mare; Grossberg, Maarja; Mikli, Valdek

2018-04-01

The control of morphology, elemental composition and phase composition of Cu2ZnSnS4 (CZTS) nano-crystals depends on the control of complex formation and surface stabilization of nano-particles in solution-based synthesis in oleylamine. At temperatures ≥280 °C, the control of nano-crystal's morphology and homogenous growth is difficult because of fast poly-nuclear growth occurring at higher temperatures. In the present work the effect of oleylamine complex formation with different alkali ions (Na+, K+ and Cs+) on nano-crystals growth at synthesis temperature of 280 °C was studied. It was found that nano-powders synthesized in the presence of Na+ and K+ ions showed the formation of crystals of different sizes - small nano-particles (18 nm-30 nm), large aggregated crystals (few nm to 1 μm) and large single crystals (1 μm - 4 μm). The presence of Cs+ ions in the nano-powder synthesis in oleylamine-metal precursor-CsOH solution promoted growth of nano-crystals of homogenous size. It is proposed that the formed oleylamine-Cs complexes a) enhance the formation and stabilization of oleylamine-metal (Cu, Zn and Sn) complexes before the injection of sulphur precursor into the oleylamine-metal precursor solution and b) after addition of sulphur stabilize the fast nucleated nano-particles and promote diffusion limited growth.

THE DETECTION RATE OF EARLY UV EMISSION FROM SUPERNOVAE: A DEDICATED GALEX/PTF SURVEY AND CALIBRATED THEORETICAL ESTIMATES

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

Ganot, Noam; Gal-Yam, Avishay; Ofek, Eran O.

The radius and surface composition of an exploding massive star, as well as the explosion energy per unit mass, can be measured using early UV observations of core-collapse supernovae (SNe). We present the first results from a simultaneous GALEX/PTF search for early ultraviolet (UV) emission from SNe. Six SNe II and one Type II superluminous SN (SLSN-II) are clearly detected in the GALEX near-UV (NUV) data. We compare our detection rate with theoretical estimates based on early, shock-cooling UV light curves calculated from models that fit existing Swift and GALEX observations well, combined with volumetric SN rates. We find thatmore » our observations are in good agreement with calculated rates assuming that red supergiants (RSGs) explode with fiducial radii of 500 R{sub ⊙}, explosion energies of 10{sup 51} erg, and ejecta masses of 10 M{sub ⊙}. Exploding blue supergiants and Wolf–Rayet stars are poorly constrained. We describe how such observations can be used to derive the progenitor radius, surface composition, and explosion energy per unit mass of such SN events, and we demonstrate why UV observations are critical for such measurements. We use the fiducial RSG parameters to estimate the detection rate of SNe during the shock-cooling phase (<1 day after explosion) for several ground-based surveys (PTF, ZTF, and LSST). We show that the proposed wide-field UV explorer ULTRASAT mission is expected to find >85 SNe per year (∼0.5 SN per deg{sup 2}), independent of host galaxy extinction, down to an NUV detection limit of 21.5 mag AB. Our pilot GALEX/PTF project thus convincingly demonstrates that a dedicated, systematic SN survey at the NUV band is a compelling method to study how massive stars end their life.« less

Synthesis of HAP nano rods and processing of nano-size ceramic reinforced poly(L)lactic acid composites

NASA Astrophysics Data System (ADS)

Flanigan, Kyle Yusef

2000-09-01

Bone is unique among the various connective tissues in that it is a composite of organic and inorganic components. Calcium phosphates occur principally in the form of hydroxyapatite crystals {Ca10(PO4) 6(OH)2}. Secreted apatite crystals are integral to the structural rigidity of the bone. When a bone breaks, there is often a need to implant an orthotic device to support the broken bone during remodeling. Current technologies use either metal pins and screws that need to be removed (by surgery) once the healing is complete or polymeric materials that either get resorbed or are porous enough to allow bone ingrowth. Poly(L)Lactic acid and copolymers of polyglycolic acid (PGA) are thermoplastics which show promise as the matrix material in biosorbable/load bearing implants. In service this material is hydrolyzed generating water and L-lactate. Orthoses composed of neat PLLA resins require greater than three years for complete resorbtion, however; 95% of strength is lost in 2 to 3 weeks in-vitro. This has limited the deployment of load bearing PLLA to screws, pins or short bracing spans. There exists a need for the development of an implantable and biosorbable orthotic device which will retain its structural integrity long enough for remodeling and healing process to generate new bone material, about 10 weeks. The scope of this dissertation is the development of HAP nano-whisker reinforcement and a HAP/PLLA thermoplastic composite. As proof of the feasibility of generating nano-reinforcement PLLA-composites, the surface of a galleried clay, montmorillonite, was modified and clay/PLLA composites processed and then characterized. Hydroxyapatite nano-whiskers were synthesized and functionalized using organosilanes and Menhaden fish-oil (common organic dispersant). The functionalized nano-fibers were used to process HAP/PLLA composites. Characterization techniques included thermal analysis, magnetic spectroscopy, XRD and ICP analysis and electron microscopy. The montmorillonite galleries were successfully intercalated and exfoliated. Gallery spacings increased as much as 30A with ODA. NMR results demonstrated that the ODA in the galleries of the highly loaded clay is in an extended trans-configuration at lower temperatures. Furthermore the alkyl chains are nano-constrained and have limited mobility. These configurations influence the gallery spacing. The appearance of two crystalline melts (DSC) may indicate that the desired physicochemical modification of the PLLA at the clay nano-reinforcement interface was achieved. For the growth of HAP nano-rods a hydrothermal synthesis route was developed. A kinetics study revealed several unique features of the method of growth. TEM analysis indicates that the synthesis procedure was successful in generating rod-like HAP structures of 100nm length and 10 nm in width. The effect of synthesis conditions on the phase purity and the morphology of the precipitates was investigated. The surface of the HAP rods was modified using OTS and OMS. The surface modified HAP was used to process HAP/PLLA composites. The properties of the composites depend strongly on the nature of the interface. Composites made with OMS or OTS demonstrated a higher elastic modulus. At 1% solids loading the OTS treated sample generated a 40% increase in modulus. Silane treated composites had DMA transitions shifted 10 to 20 degrees higher. "Well-ordered" SAMs improve the dispersion of the inorganic reinforcement in PLLA and promote the formation of mechanical entanglements at the HAP-PLLA interface. As a result load transfer is more complete resulting in higher modulus material.

Sulfur nanocrystals anchored graphene composite with highly improved electrochemical performance for lithium-sulfur batteries

NASA Astrophysics Data System (ADS)

Zhang, Jun; Dong, Zimin; Wang, Xiuli; Zhao, Xuyang; Tu, Jiangping; Su, Qingmei; Du, Gaohui

2014-12-01

Two kinds of graphene-sulfur composites with 50 wt% of sulfur are prepared using hydrothermal method and thermal mixing, respectively. Transmission Electron Microscopy (TEM) and Energy Dispersive X-ray Spectra mapping show that sulfur nanocrystals with size of ∼5 nm dispersed on graphene sheets homogeneously for the sample prepared by hydrothermal method (NanoS@G). While for the thermal mixed graphene-sulfur composite (S-G mixture), sulfur shows larger and uneven size (50-200 nm). X-ray Photoelectron Spectra (XPS) reveals the strong chemical bonding between the sulfur nanocrystals and graphene. Comparing with the S-G mixture, the NanoS@G composite shows highly improved electrochemical performance as cathode for lithium-sulfur (Li-S) battery. The NanoS@G composite delivers an initial capacity of 1400 mAh g-1 with the sulfur utilization of 83.7% at a current density of 335 mA g-1. The capacity keeps above 720 mAh g-1 over 100 cycles. The strong adherence of the sulfur nanocrystals on graphene immobilizes sulfur and polysulfides species and suppressed the "shuttle effect", resulting higher coulombic efficiency and better capacity retention. Electrochemical impedance also suggests that the strong bonding enabled rapid electronic/ionic transport and improved electrochemical kinetics, therefore good rate capability is obtained. These results demonstrate that the NanoS@G composite is a very promising candidate for high-performance Li-S batteries.

[Photophysical properties of poly (2-methoxy-5-octyloxy)-p-phenylene vinylene/TiO2 nano-composites].

PubMed

Sun, Jian-ping; Weng, Jia-bao; Cheng, Yun-tao; Lin, Ting; Huang, Xiao-zhu

2008-12-01

The photoelectric composites of poly (2-methoxy-5-octyloxy)-p-phenylene vinylene/nanometer TiO2 (PMOCOPV/ TiO2) with different nanometer TiOz amount were synthesized through dehydrochlorination in-situ polymerization. The results of Fourier transform infrared spectroscopy and Raman spectroscopy indicated that the surface of nanometer TiO2 was coated with PMOCOPV. UV-Vis spectrum showed that the absorption of PMOCOPV/TiO2 nano-composites was strengthened in the range of violet and visible light with the contents of TiO2 increasing. The composite dimensions were observed by highly resolution transmission electron microscope, PMOCOPV/TiO2 nano-composites dispersed uniformly and possessed core-shell structure, the diameter of PMOCOPV/TiO2 was measured to be about 30 nm, and the thickness of the PMOCOPV coating was about 8-10 nm. Photoluminescence spectroscopy indicated that the maximum emission wavelength of the PMOCOPV/TiO2 was red-shifted with increasing TiO2 concentration. The fluorescence lifetime of PMOCOPV/TiO2 was about 1 ns. The intensity and lifetime of fluorescence was increased remarkably with the contents of TiO2 increasing. The mechanism of the strengthened fluorescence quantum efficiency and fluorescence intensity of PMOCOPV/TiO2 was investigated through the charge transfer, exciton dissociation and potential energy in PMOCOPV/TiO2 nano-composites.

Effect of high energy electron beam (10MeV) on specific heat capacity of low-density polyethylene/hydroxyapatite nano-composite.

PubMed

Soltani, Z; Ziaie, F; Ghaffari, M; Beigzadeh, A M

2017-02-01

In the present work, thermal properties of low density polyethylene (LDPE) and its nano composites are investigated. For this purpose LDPE reinforced with different weight percents of hydroxyapatite (HAP) powder which was synthesized via hydrolysis method are produced. The samples were irradiated with 10MeV electron beam at doses of 75 to 250kGy. Specific heat capacity measurement have been carried out at different temperatures, i.e. 25, 50, 75 and 100°C using modulated temperature differential scanning calorimetry (MTDSC) apparatus and the effect of three parameters include of temperature, irradiation dose and the amount of HAP nano particles as additives on the specific heat capacity of PE/HAP have been investigated precisely. The MTDSC results indicate that the specific heat capacity have decreased by addition of nano sized HAP as reinforcement for LDPE. On the other hand, the effect of radiation dose is reduction in the specific heat capacity in all materials including LDPE and its nano composites. The HAP nano particles along with cross-link junctions due to radiation restrain the movement of the polymer chains in the vicinity of each particle and improve the immobility of polymer chains and consequently lead to reduction in specific heat capacity. Also, the obtained results confirm that the radiation effect on the specific heat capacity is more efficient than the reinforcing effect of nano-sized hydroxyapatite. Copyright © 2016 Elsevier B.V. All rights reserved.

Series of Two Droplets on Fiber Approaching Ignition

NASA Technical Reports Server (NTRS)

2003-01-01

The Fiber-Supported Droplet Combustion (FSDC) uses two droplets positioned on the fiber wire, instead of the usual one. Two droplets more closely simulates the environment in engines, which ignite many fuel droplets at once. The behavior of the burning was also unexpected -- the droplets moved together after ignition, generating quite a bit of data for understanding the interaction of fuel droplets while they burn. Because FSDC is backlit (the bright glow behind the drops), you carnot see the glow of the droplets while they burn -- instead, you see them shrink! The small blobs left on the wire after the burn are the beads used to center the fuel droplet on the wire. This image was taken on STS-94, July 12, 1997, MET:10/19:13 (approximate). FSDC-2 studied fundamental phenomena related to liquid fuel droplet combustion in air. Pure fuels and mixtures of fuels were burned as isolated single and dual droplets with and without forced air convection. The FSDC guest investigator was Forman Williams, University of California, San Diego. The experiment was part of the space research investigations conducted during the Microgravity Science Laboratory-1R mission (STS-94, July 1-17 1997). Advanced combustion experiments will be a part of investigations planned for the International Space Station. (251KB JPEG, 1350 x 1523 pixels; downlinked video, higher quality not available) The MPG from which this composite was made is available at http://mix.msfc.nasa.gov/ABSTRACTS/MSFC-0300179.html

Dynamic measurements and simulations of airborne picolitre-droplet coalescence in holographic optical tweezers

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

Bzdek, Bryan R.; Reid, Jonathan P., E-mail: j.p.reid@bristol.ac.uk; Collard, Liam

We report studies of the coalescence of pairs of picolitre aerosol droplets manipulated with holographic optical tweezers, probing the shape relaxation dynamics following coalescence by simultaneously monitoring the intensity of elastic backscattered light (EBL) from the trapping laser beam (time resolution on the order of 100 ns) while recording high frame rate camera images (time resolution <10 μs). The goals of this work are to: resolve the dynamics of droplet coalescence in holographic optical traps; assign the origin of key features in the time-dependent EBL intensity; and validate the use of the EBL alone to precisely determine droplet surface tensionmore » and viscosity. For low viscosity droplets, two sequential processes are evident: binary coalescence first results from the overlap of the optical traps on the time scale of microseconds followed by the recapture of the composite droplet in an optical trap on the time scale of milliseconds. As droplet viscosity increases, the relaxation in droplet shape eventually occurs on the same time scale as recapture, resulting in a convoluted evolution of the EBL intensity that inhibits quantitative determination of the relaxation time scale. Droplet coalescence was simulated using a computational framework to validate both experimental approaches. The results indicate that time-dependent monitoring of droplet shape from the EBL intensity allows for robust determination of properties such as surface tension and viscosity. Finally, the potential of high frame rate imaging to examine the coalescence of dissimilar viscosity droplets is discussed.« less

Intercomparison between Individual Particles Scavenged as CCN and Those Collected at Ground-based Site on West Coast of Japan During Asian Dust Storm

NASA Astrophysics Data System (ADS)

Ma, C. J.; Tohno, S.; Kasahara, M.; Hayakawa, S.

2002-12-01

Asian dust storm particles can affect precipitation composition because they are either incorporated into cloud via condensation of water vapour (nucleation) or due to the uptake of particles by existing droplets. And subsequently they affect aquatic and terrestrial ecosystems. In order to study the intercorrelation between the chemical natures of both the particles collected at ground-based site and those scavenged as CCN, the intensive field measurement was carried out on west coast of Japan (Yasaka, Tango Peninsula, 35.62°N; 135.07°E) during dense Asian dust storm event on March 22, 2002. Due to the size dependence of the chemical composition of aerosol particle, size-segregated aerosol particles were collect using Low pressure Andersen impactor sampler. Also, to collect cloud droplets individually, a particular method for the cloud droplet replication was newly applied using collodion (nitrocellulose) film. Sampling of cloud droplets was performed at summit of a mountain (680 m) in Yasaka. To analyze the ambient individual aerosol particles and individual retained particles in cloud droplet, X-ray fluorescence (XRF) analytical method set at SPring-8 on BL39XU was applied. Analytical result enables us not only to compare the characteristics of individual particles scavenged as CCN and those collected at ground-based site, but also to estimate the influence of long-range transport.

[The photoluminescence and absorption properties of Co/AAO nano-array composites].

PubMed

Li, Shou-Yi; Wang, Cheng-Wei; Li, Yan; Wang, Jian; Ma, Bao-Hong

2008-03-01

Ordered Co/AAO nano-array structures were fabricated by alternating current (AC) electrodeposition method within the cylindrical pores of anodic aluminum oxide (AAO) template prepared in oxalic acid electrolyte. The photoluminescence (PL) emission and photoabsorption of AAO templates and Co/AAO nano-array structures were investigated respectively. The results show that a marked photoluminescence band of AAO membranes occurs in the wavelength range of 350-550 nm and their PL peak position is at 395 nm. And with the increase in the deposition amount of Co nanoparticles, the PL intensity of Co/AAO nano-array structures decreases gradually, and their peak positions of the PL are invariable (395 nm). Meanwhile the absorption edges of Co/AAO show a larger redshift, and the largest shift from the near ultraviolet to the infrared exceeds 380 nm. The above phenomena caused by Co nano-particles in Co/AAO composite were analyzed.

The effect of different surfactants/plastisizers on the electrical behavior of CNT nano-modified cement mortars

NASA Astrophysics Data System (ADS)

Dalla, P. T.; Alafogianni, P.; Tragazikis, I. K.; Exarchos, D. A.; Dassios, K.; Barkoula, N.-M.; Matikas, T. E.

2015-03-01

Cement-based materials have in general low electrical conductivity. Electrical conductivity is the measure of the ability of the material to resist the passage of electrical current. The addition of a conductive admixture such as Multi-Walled Carbon Nanotubes (MWCNTs) in a cement-based material increases the conductivity of the structure. This research aims to characterize nano-modified cement mortars with MWCNT reinforcements. Such nano-composites would possess smartness and multi-functionality. Multifunctional properties include electrical, thermal and piezo-electric characteristics. One of these properties, the electrical conductivity, was measured using a custom made apparatus that allows application of known D.C. voltage on the nano-composite. In this study, the influence of different surfactants/plasticizers on CNT nano-modified cement mortar specimens with various concentrations of CNTs (0.2% wt. cement CNTs - 0.8% wt. cement CNTs) on the electrical conductivity is assessed.

Wear characterization of nano-hydroxyapatite with addition of titanium (HA-Ti)

NASA Astrophysics Data System (ADS)

Rosmamuhamadani, R.; Arawi, A. Z. O.; Talari, M. K.; Mahat, M. M.; Bonnia, N. N.; Sabrina; Yahaya, M.; Sulaiman, S.; Ismail, M. I. S.

2018-04-01

Hydroxyapatite (Ca10 (PO4)6(OH)2, HA), is an attractive material of an inorganic compound whose chemical composition and crystallographic structures are similar to the composition of the bone. A natural source such as egg shells is composed of 94 wt. % of calcium carbonate (CaCO3), which can be calcined as calcium oxide (CaO) by the calcinations process. The efficient temperature to produce CaO is 900 °C for 2 hours. The synthesis of nano-HA was done by the mixing the diammonium phosphate (DAP) and calcium hydroxide (Ca(OH)2) and subjected into a microwave for 30 minutes at 1100 W irradiation power. Ball milling process was used for 30 minutes to mix the nano-HA with different compositions of titanium. These were pressed to form pallets by hand hydraulic pump (force=2300 psi). The pallets then were sintered at 1200 °C with the heating rate of 3 °C/min for 2 hours. The pallets were tested by several mechanical testing including hardness, compression strength and wear. From the results, HA-25wt. %Ti composite gave the highest hardness, compression and coefficient of friction for wear test values which were 89.6 Hv, 82.5MPa and 0.76μ respectively. It showed that by adding Ti to nano-HA, the mechanical properties of nano-HA could be enhanced. The microstructure analyses by optical micrograph showed that nano-HA-Ti particles displayed shape likes needle morphology. The particles showed the high tendency to form the agglomerations.

Internal and surface phenomena in metal combustion

NASA Technical Reports Server (NTRS)

Dreizin, Edward L.; Molodetsky, Irina E.; Law, Chung K.

1995-01-01

Combustion of metals has been widely studied in the past, primarily because of their high oxidation enthalpies. A general understanding of metal combustion has been developed based on the recognition of the existence of both vapor-phase and surface reactions and involvement of the reaction products in the ensuing heterogeneous combustion. However, distinct features often observed in metal particle combustion, such as brightness oscillations and jumps (spearpoints), disruptive burning, and non-symmetric flames are not currently understood. Recent metal combustion experiments using uniform high-temperature metal droplets produced by a novel micro-arc technique have indicated that oxygen dissolves in the interior of burning particles of certain metals and that the subsequent transformations of the metal-oxygen solutions into stoichiometric oxides are accompanied with sufficient heat release to cause observed brightness and temperature jumps. Similar oxygen dissolution has been observed in recent experiments on bulk iron combustion but has not been associated with such dramatic effects. This research addresses heterogeneous metal droplet combustion, specifically focusing on oxygen penetration into the burning metal droplets, and its influence on the metal combustion rate, temperature history, and disruptive burning. A unique feature of the experimental approach is the combination of the microgravity environment with a novel micro-arc Generator of Monodispersed Metal Droplets (GEMMED), ensuring repeatable formation and ignition of uniform metal droplets with controllable initial temperature and velocity. The droplet initial temperatures can be adjusted within a wide range from just above the metal melting point, which provides means to ignite droplets instantly upon entering an oxygen containing environment. Initial droplet velocity will be set equal to zero allowing one to organize metal combustion microgravity experiments in a fashion similar to usual microgravity liquid fuel droplet combustion studies. In addition, the internal compositions of rapidly quenched metal particles will be analyzed using SEM technique. Such compositions are similar to those existing during the combustion and provide new insight on metal combustion processes. The results of this experimental work will be used to model the fundamental mechanisms of metal combustion. Preliminary experimental results on Al and Zr particle combustion at normal gravity are discussed here.

Sonocatalytic degradation of some dyestuffs and comparison of catalytic activities of nano-sized TiO2, nano-sized ZnO and composite TiO2/ZnO powders under ultrasonic irradiation.

PubMed

Wang, Jun; Jiang, Zhe; Zhang, Liqun; Kang, Pingli; Xie, Yingpeng; Lv, Yanhui; Xu, Rui; Zhang, Xiangdong

2009-02-01

Here, a novel sonocatalyst, composite TiO2/ZnO powder, was prepared through the combination of nano-sized TiO2 and ZnO powders. Because of the appropriate adsorbability to organic pollutants and special crystal interphase between TiO2 and ZnO particles, the composite TiO2/ZnO powder exhibits a high sonocatalytic activity under ultrasonic irradiation during the degradation of acid red B. Especially, the sonocatalytic activity of composite TiO2/ZnO powder with 4:1 molar proportion treated at 500 degrees C for 50 min showed obvious improvement compared with pure nano-sized TiO2 and ZnO powders. When the experimental conditions such as 10mg/L acid red B concentration, 1.0 g/L catalyst addition amount, pH=7.0, 20 degrees C system temperature, 100 min ultrasonic time and 50 mL total volume were adopted, the satisfactory degradation ratio and rate were obtained. All experiments indicate that the sonocatalytic method using composite TiO2/ZnO powder may be a more advisable choice for the treatments of non- or low-transparent organic wastewaters in future.

A study on the tensile properties of silicone rubber/polypropylene fibers/silica hybrid nanocomposites.

PubMed

Ziraki, Sahar; Zebarjad, Seyed Mojtaba; Hadianfard, Mohammad Jafar

2016-04-01

Metacarpophalangeal joint implants have been usually made of silicone rubber. In the current study, silica nano particles and polypropylene fibers were added to silicone rubber to improve silicone properties. The effect of the addition of silica nano particles and polypropylene fibers on the tensile behavior of the resultant composites were investigated. Composite samples with different content of PP fibers and Silica nano particles (i. e. 0, 1 and 2wt%) as well as the hybrid composite of silicone rubber with 1wt% SiO2 and 1wt% PP fiber were prepared. Tensile tests were done at constant cross head speed. To study the body fluid effect on the mechanical properties of silicone rubber composites, samples soaked in simulated body fluid (SBF) at 37°C were also tested. The morphology of the samples were studied by scanning electron microscope. Results of analysis revealed that an increase in PP fibers and silica nano particles content to 2wt%, increases the tensile strength of silicone rubber of about 75% and 42% respectively. It was found out that the strength of the samples decreases after being soaked in simulated body fluid, though composites with PP fibers as the reinforcement showed less property degradation. Copyright © 2016 Elsevier Ltd. All rights reserved.

Magnetization enhancement due to incorporation of non-magnetic nitrogen content in (Co{sub 84}Zr{sub 16})N{sub x} nano-composite films

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

Singh, Jitendra, E-mail: jitendra@ceeri.ernet.in; Akhtar, Jamil; Academy of Scientific and Innovative Research, New Delhi 110001

We report the magnetic, electronic, and structural properties of nano-composite (Co{sub 84}Zr{sub 16})N{sub x} or CZN films prepared by reactive co-sputter deposition method. As-deposited CZN films have shown enhancement in magnetization (M{sub s}) with incorporation of nitrogen content, which is related to the evolution of nano-composite phase. X-ray diffraction study has confirmed poly-crystalline growth of CZN films with fcc(331) and fcc(422) phases. High-resolution transmission electron microscope study reveals that CZN films are composed of ordered and crystalline ferromagnetic Co nano-clusters, which are embedded in the nano-composite matrix. Photoemission measurements show the change in the intensity near the Fermi level mostmore » likely due to defects and shift in the core-levels binding energy with nitrogen concentration. Raman spectroscopy data show an increase in the intensity of the Raman lines with nitrogen concentration upto 20%. However, the intensity is significantly lower for 30% sample. This indicates that less nitrogen or defect states are being substituted into the lattice above 20% and is consistent with the observed magnetic behavior. Our studies indicate that defects induced due to the incorporation of non-magnetic nitrogen content play a key role to enhance the magnetization.« less

Combustion Stages of a Single Heavy Oil Droplet in Microgravity

NASA Technical Reports Server (NTRS)

Ikegami, M.; Xu, G.; Ikeda, K.; Honma, S.; Nagaishi, H.; Dietrich, D. L.; Struk, P. M.; Takeshita, Y.

2001-01-01

Heavy oil is a common fuel for industrial furnaces, boilers, marines and diesel engines. Previous studies showed that the combustion of heavy oil involves not only the complete burning of volatile matters but also the burn-out of coke residues. Detailed knowledge about heavy oil combustion therefore requires an understanding of the different burning stages of heavy oil droplets in the burner. This in turn, demands knowledge about the single droplet evaporation and combustion characteristics. This study measured the temperature and size histories of heavy oil (C glass) droplets burning in microgravity to elucidate the various stages that occur during combustion. The elimination of the gravity-induced gas convection in microgravity allows the droplet combustion to be studied in greater detail. Noting that the compositions of heavy oil are various, we also tested the fuel blends of a diesel light oil (LO) and a heavy oil residue (HOR).

Chemical composition of polluted mist droplets

NASA Astrophysics Data System (ADS)

Igawa, Manabu; Kamijo, Kosuke; Nanzai, Ben; Matsumoto, Kiyoshi

2017-12-01

Mist events occur frequently worldwide, but the chemical characteristics of the mist droplets has never been investigated because of very low liquid water contents of them. We estimated the concentrations of the mist water, the average concentration of the mist droplets, via the determination of water-soluble components of the coarse aerosol and the observation of the imprints of the droplets on a MgO-coated glass slide. The pH of the mist water was estimated from the equilibrium calculation with the data of the Gran plot of the solution of the dissolved coarse particles, the inorganic ion concentrations of aerosol larger than 10 μm, and the estimated volume of mist water. The mist water was measured as about 1 eq/L total concentration for typical inorganic ions and about pH 4.5 in Yokohama. Such highly concentrated mist droplets may have intense environmental effects.

Detailed finite element method modeling of evaporating multi-component droplets

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

Diddens, Christian, E-mail: C.Diddens@tue.nl

The evaporation of sessile multi-component droplets is modeled with an axisymmetic finite element method. The model comprises the coupled processes of mixture evaporation, multi-component flow with composition-dependent fluid properties and thermal effects. Based on representative examples of water–glycerol and water–ethanol droplets, regular and chaotic examples of solutal Marangoni flows are discussed. Furthermore, the relevance of the substrate thickness for the evaporative cooling of volatile binary mixture droplets is pointed out. It is shown how the evaporation of the more volatile component can drastically decrease the interface temperature, so that ambient vapor of the less volatile component condenses on the droplet.more » Finally, results of this model are compared with corresponding results of a lubrication theory model, showing that the application of lubrication theory can cause considerable errors even for moderate contact angles of 40°. - Graphical abstract:.« less

Capacitive sensing of droplets for microfluidic devices based on thermocapillary actuation.

PubMed

Chen, Jian Z; Darhuber, Anton A; Troian, Sandra M; Wagner, Sigurd

2004-10-01

The design and performance of a miniaturized coplanar capacitive sensor is presented whose electrode arrays can also function as resistive microheaters for thermocapillary actuation of liquid films and droplets. Optimal compromise between large capacitive signal and high spatial resolution is obtained for electrode widths comparable to the liquid film thickness measured, in agreement with supporting numerical simulations which include mutual capacitance effects. An interdigitated, variable width design, allowing for wider central electrodes, increases the capacitive signal for liquid structures with non-uniform height profiles. The capacitive resolution and time response of the current design is approximately 0.03 pF and 10 ms, respectively, which makes possible a number of sensing functions for nanoliter droplets. These include detection of droplet position, size, composition or percentage water uptake for hygroscopic liquids. Its rapid response time allows measurements of the rate of mass loss in evaporating droplets.

Self-Bound Quantum Droplets of Atomic Mixtures in Free Space

NASA Astrophysics Data System (ADS)

Semeghini, G.; Ferioli, G.; Masi, L.; Mazzinghi, C.; Wolswijk, L.; Minardi, F.; Modugno, M.; Modugno, G.; Inguscio, M.; Fattori, M.

2018-06-01

Self-bound quantum droplets are a newly discovered phase in the context of ultracold atoms. In this Letter, we report their experimental realization following the original proposal by Petrov [Phys. Rev. Lett. 115, 155302 (2015), 10.1103/PhysRevLett.115.155302], using an attractive bosonic mixture. In this system, spherical droplets form due to the balance of competing attractive and repulsive forces, provided by the mean-field energy close to the collapse threshold and the first-order correction due to quantum fluctuations. Thanks to an optical levitating potential with negligible residual confinement, we observe self-bound droplets in free space, and we characterize the conditions for their formation as well as their size and composition. This work sets the stage for future studies on quantum droplets, from the measurement of their peculiar excitation spectrum to the exploration of their superfluid nature.

Selective laser sintering fabrication of nano-hydroxyapatite/poly-ε-caprolactone scaffolds for bone tissue engineering applications

PubMed Central

Xia, Yan; Zhou, Panyu; Cheng, Xiaosong; Xie, Yang; Liang, Chong; Li, Chao; Xu, Shuogui

2013-01-01

The regeneration of functional tissue in osseous defects is a formidable challenge in orthopedic surgery. In the present study, a novel biomimetic composite scaffold, here called nano-hydroxyapatite (HA)/poly-ε-caprolactone (PCL) was fabricated using a selective laser sintering technique. The macrostructure, morphology, and mechanical strength of the scaffolds were characterized. Scanning electronic microscopy (SEM) showed that the nano-HA/PCL scaffolds exhibited predesigned, well-ordered macropores and interconnected micropores. The scaffolds have a range of porosity from 78.54% to 70.31%, and a corresponding compressive strength of 1.38 MPa to 3.17 MPa. Human bone marrow stromal cells were seeded onto the nano-HA/PCL or PCL scaffolds and cultured for 28 days in vitro. As indicated by the level of cell attachment and proliferation, the nano-HA/PCL showed excellent biocompatibility, comparable to that of PCL scaffolds. The hydrophilicity, mineralization, alkaline phosphatase activity, and Alizarin Red S staining indicated that the nano-HA/PCL scaffolds are more bioactive than the PCL scaffolds in vitro. Measurements of recombinant human bone morphogenetic protein-2 (rhBMP-2) release kinetics showed that after nano-HA was added, the material increased the rate of rhBMP-2 release. To investigate the in vivo biocompatibility and osteogenesis of the composite scaffolds, both nano-HA/PCL scaffolds and PCL scaffolds were implanted in rabbit femur defects for 3, 6, and 9 weeks. The wounds were studied radiographically and histologically. The in vivo results showed that both nano-HA/PCL composite scaffolds and PCL scaffolds exhibited good biocompatibility. However, the nano-HA/PCL scaffolds enhanced the efficiency of new bone formation more than PCL scaffolds and fulfilled all the basic requirements of bone tissue engineering scaffolds. Thus, they show large potential for use in orthopedic and reconstructive surgery. PMID:24204147

Material Property Characterization of Potential Nanocarbon Metal-Matrix Composite: An Investigational Study

NASA Astrophysics Data System (ADS)

Zavala, Mitchel

Metal-matrix composites (MMCs) are engineered combinations of two or more materials. Tailored properties are achieved by systematic combinations of different constituents. Specialized design and synthesis procedures allow unique sets of material properties in composites. Covetics are a new type of metal-matrix nano-composite (MMnC) material. These materials are formed from FCC metals which are super-saturated with up to 10 wt. % of activated nano-carbon powder. The idea is that the nano-carbon particles will enhance the material properties of the base metal matrix, however most of the physical and mechanical properties of covetics have not been well characterized. The foci of this study are to optimize the covetic casting synthesis process under controlled conditions, to understand and analyze the microstructures of the synthesized copper and aluminum covetic, to provide a thorough analysis of the chemical composition of the synthesized covetic materials, and to characterize physical and mechanical properties of both of these materials using meticulously prepared samples and test procedures.

Characteristics of ADC12/nano Al2O3composites with Addition of Ti Produced By Stir Casting Method

NASA Astrophysics Data System (ADS)

Zulfia, A.; Krisiphala; Ferdian, D.; Utomo, B. W.; Dhaneswara, D.

2018-03-01

The mechanical properties and microstructure of ADC12/nano Al2O3 matrix composites have been studied in this work. The composites were produced by stir casting method. ADC 12 as matrix composites was combined by Mg and Ti. The addition of Ti was varied from 0.02 to 0.08 wt-% as grain refinement wetting to improve mechanical properties such as tensile strength, hardness and wear resistance, while Mg addition was to promote wetting between ADC 12 and nano Al2O3. The optimum tensile strength was found at 0.04 wt-% addition of Ti with value of 132.5 MPa, further adding more Ti cause a poisoning mechanism that will hindered the grain refining process and reduce the tensile strength. The hardness and wear resistance of composites would also increase because of the refinement process. and the added Magnesium in the material that will form Mg2Si primary phases who have a high hardness value.

Preparation and mechanical properties of carbon nanotube-silicon nitride nano-ceramic matrix composites

NASA Astrophysics Data System (ADS)

Tian, C. Y.; Jiang, H.

2018-01-01

Carbon nanotube-silicon nitride nano-ceramic matrix composites were fabricated by hot-pressing nano-sized Si3N4 powders and carbon nanotubes. The effect of CNTs on the mechanical properties of silicon nitride was researched. The phase compositions and the microstructure characteristics of the samples as well as the distribution of carbon nanotube in the silicon nitride ceramic were analyzed by X-ray diffraction and scanning electron microscope. The results show that the microstructure of composites consists mainly of α-Si3N4, β-Si3N4, Si2N2O and carbon natubes. The addition of proper amount of carbon nanotubes can improve the fracture toughness and the flexural strength, and the optimal amount of carbon nanotube are both 3wt.%. However the Vickers hardness values decrease with the increase of carbon nanotubes content.

Carbon Nanotubes Blended Hydroxyapatite Ethanol Sensor

NASA Astrophysics Data System (ADS)

Anjum, S. R.; Khairnar, R. S.

2016-12-01

Nano crystals of Hydroxyapatite (HAp) were synthesized by a wet chemical precipitation method. The nano composite materials were developed by doping various weight concentrations of carbon nanotubes in HAp, followed by characterization using scanning electron microscopy, and X-ray diffraction. Thick films of these materials were prepared by using screen printing technique. The ethanol sensing properties of these nano crystals and nano composite films were investigated by two probe electrical method. The gas sensing features such as operating temperature, response and recovery time, maximum gas detection limit, etc. were studied, since these parameters are of prime importance for sensor. The results revealed that at room temperature, the composite materials exhibited improved sensing performance towards 100 ppm ethanol with fast response times. It also showed shorter recovery time with higher vapor uptake capacity. The ethanol adsorption processes on doped and undoped substrates can be explained by surface chemical reactions as well as providing the possible adsorption models. The novelty of this work lies in developing reusable sensor substrates for room temperature sensing.

Nano-Particle Enhanced Polymer Materials for Space Flight Applications

NASA Technical Reports Server (NTRS)

Criss, Jim M., Jr.; Powell, William D.; Connell, John W.; Stallworth-Bordain, Yemaya; Brown, Tracy R.; Mintz, Eric A.; Schlea, Michelle R.; Shofne, Meisha L.

2009-01-01

Recent advances in materials technology both in polymer chemistry and nano-materials warrant development of enhanced structures for space flight applications. This work aims to develop spacecraft structures based on polymer matrix composites (PMCs) that utilize these advancements.. Multi-wall carbon nano-tubes (MWCNTs) are expected ·to increase mechanical performance, lower coefficient of thermal expansion (CTE), increase electrical conductivity (mitigate electrostatic charge), increase thermal conductivity, and reduce moisture absorption of the resultant space structures. In this work, blends of MWCNTs with PETI-330 were prepared and characterized. The nano-reinforced resins were then resin transfer molded (RTM) into composite panels using M55J carbon fabric and compared to baseline panels fabricated from a cyanate ester (RS-3) or a polyimide (PETI-330) resin containing no MWCNTs. In addition, methods of pre-loading the fabric with the MWCNTs were also investigated. The effects of the MWCNTs on the resin processing properties and on the composite end-use properties were also determined.

The Effect of CuO Nanoparticles on Antimicrobial Effects and Shear Bond Strength of Orthodontic Adhesives

PubMed Central

Toodehzaeim, Mohammad Hossein; Zandi, Hengameh; Meshkani, Hamidreza; Hosseinzadeh Firouzabadi, Azadeh

2018-01-01

Statement of the Problem: Orthodontic appliances facilitate microbial plaque accumulation and increase the chance of white spot lesions. There is a need for new plaque control methods independent of patient's cooperation. Purpose: The aim of this study was to determine the effects of incorporating copper oxide (CuO) nanoparticles on antimicrobial properties and bond strength of orthodontic adhesive. Materials and Method: CuO nanoparticles were added to the composite transbond XT at concentrations of 0.01, 0.5 and 1 wt.%. To evaluate the antimicrobial properties of composites containing nanoparticles, the disk agar diffusion test was used. For this purpose, 10 discs from each concentration of nano-composites (totally 30 discs) and 10 discs from conventional composite (as the control group) were prepared. Then the diameter of streptococcus mutans growth inhibition around each disc was determined in blood agar medium. To evaluate the shear bond strength, with each concentration of nano-composites as well as the control group (conventional composite), 10 metal brackets were bonded to the human premolars and shear bond strength was determined using a universal testing machine. Results: Nano-composites in all three concentrations showed significant antimicrobial effect compared to the control group (p< 0.001). With increasing concentration of nanoparticles, antimicrobial effect showed an upward trend, although statistically was not significant. There was no significant difference between the shear bond strength of nano-composites compared to control group (p= 0.695). Conclusion: Incorporating CuO nanoparticles into adhesive in all three studied concentrations added antimicrobial effects to the adhesive with no adverse effects on shear bond strength. PMID:29492409

The Effect of CuO Nanoparticles on Antimicrobial Effects and Shear Bond Strength of Orthodontic Adhesives.

PubMed

Toodehzaeim, Mohammad Hossein; Zandi, Hengameh; Meshkani, Hamidreza; Hosseinzadeh Firouzabadi, Azadeh

2018-03-01

Orthodontic appliances facilitate microbial plaque accumulation and increase the chance of white spot lesions. There is a need for new plaque control methods independent of patient's cooperation. The aim of this study was to determine the effects of incorporating copper oxide (CuO) nanoparticles on antimicrobial properties and bond strength of orthodontic adhesive. CuO nanoparticles were added to the composite transbond XT at concentrations of 0.01, 0.5 and 1 wt.%. To evaluate the antimicrobial properties of composites containing nanoparticles, the disk agar diffusion test was used. For this purpose, 10 discs from each concentration of nano-composites (totally 30 discs) and 10 discs from conventional composite (as the control group) were prepared. Then the diameter of streptococcus mutans growth inhibition around each disc was determined in blood agar medium. To evaluate the shear bond strength, with each concentration of nano-composites as well as the control group (conventional composite), 10 metal brackets were bonded to the human premolars and shear bond strength was determined using a universal testing machine. Nano-composites in all three concentrations showed significant antimicrobial effect compared to the control group ( p < 0.001). With increasing concentration of nanoparticles, antimicrobial effect showed an upward trend, although statistically was not significant. There was no significant difference between the shear bond strength of nano-composites compared to control group ( p = 0.695). Incorporating CuO nanoparticles into adhesive in all three studied concentrations added antimicrobial effects to the adhesive with no adverse effects on shear bond strength.

An Experimental Examination of Combustion of Isolated Liquid Fuel Droplets with Polymeric and Nanoparticle Additives

NASA Astrophysics Data System (ADS)

Ghamari, Mohsen

In spite of recent attention to renewable sources of energy, liquid hydrocarbon fuels are still the main source of energy for industrial and transportation systems. Manufactures and consumers are consistently looking for ways to optimize the efficiency of fuel combustion in terms of cost, emissions and consumer safety. In this regard, increasing burning rate of liquid fuels has been of special interest in both industrial and transportation systems. Recent studies have shown that adding combustible nano-particles could have promising effects on improving combustion performance of liquid fuels. Combustible nano-particles could enhance radiative and conductive heat transfer and also mixing within the droplet. Polymeric additive have also shown promising effect on improving fire safety by suppressing spreading behavior and splatter formation in case of crash scenario. Polymers are also known to have higher burning rate than regular hydrocarbon fuels. Therefore adding polymeric additive could have the potential to increase the burning rate. In this work, combustion dynamics of liquid fuel droplets with both polymeric and nanoparticle additives is studied in normal gravity. High speed photography is employed and the effect of additive concentration on droplet burning rate, burning time, extinction and soot morphology is investigated. Polymer added fuel was found to have a volatility controlled combustion with four distinct regimes. The first three zones are associated with combustion of base fuel while the polymer burns last and after a heating zone because of its higher boiling point. Polymer addition reduces the burning rate of the base fuel in the first zone by means of increasing viscosity and results in nucleate boiling and increased burning rates in the second and third stages. Overall, polymer addition resulted in a higher burning rate and shorter burning time in most of the scenarios. Colloidal suspensions of carbon-based nanomaterials in liquid fuels were also tested at different particle loadings. It was found that dispersing nanoparticles results in higher burning rate by means of enhanced radiative heat absorption and thermal conductivity. An optimum particle loading was found for each particle type at which the maximum burning rate was achieved. It was observed that the burning rate again starts to reduce after this optimum point most likely due to the formation of large aggregates that reduce thermal conductivity and suppress the diffusion of species.

Improved Thermal Stability of Lithium-Rich Layered Oxide by Fluorine Doping.

PubMed

Kapylou, Andrei; Song, Jay Hyok; Missiul, Aleksandr; Ham, Dong Jin; Kim, Dong Han; Moon, San; Park, Jin Hwan

2018-01-05

The thermal stability of lithium-rich layered oxide with the composition Li(Li 1/6 Ni 1/6 Co 1/6 Mn 1/2 )O 2-x F x (x=0.00 and 0.05) is evaluated for use as a cathode material in lithium-ion batteries. Thermogravimetric analysis, evolved gas analysis, and differential scanning calorimetry show that, upon fluorine doping, degradation of the lithium-rich layered oxides commences at higher temperatures and the exothermic reaction is suppressed. Hot box tests also reveal that the prismatic cell with the fluorine-doped powder does not explode, whereas that with the undoped one explodes at about 135 °C with a sudden temperature increase. XRD analysis indicates that fluorine doping imparts the lithium-rich layered oxide with better thermal stability by mitigating oxygen release at elevated temperatures that cause an exothermic reaction with the electrolyte. The origin of the reduced oxygen release from the fluorinated lithium-rich layered oxide is also discussed. © 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

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

Cook, Ryan D.; Lin, Ying-Hsuan; Peng, Zhuoyu

Organic aerosol formation and transformation occurs within aqueous aerosol and cloud droplets, yet little is known about the composition of high molecular weight organic compounds in cloud water. Cloud water samples collected at Whiteface Mountain, New York, during August-September 2014 were analyzed by ultra-high-resolution mass spectrometry to investigate the molecular composition of dissolved organic carbon, with a focus on sulfur- and nitrogen-containing compounds. Organic molecular composition was evaluated in the context of cloud water inorganic ion concentrations, pH, and total organic carbon concentrations to gain insights into the sources and aqueous-phase processes of the observed high molecular weight organic compounds.more » Cloud water acidity was positively correlated with the average oxygen : carbon ratio of the organic constituents, suggesting the possibility for aqueous acid-catalyzed (prior to cloud droplet activation or during/after cloud droplet evaporation) and/or radical (within cloud droplets) oxidation processes. Many tracer compounds recently identified in laboratory studies of bulk aqueous-phase reactions were identified in the cloud water. Organosulfate compounds, with both biogenic and anthropogenic volatile organic compound precursors, were detected for cloud water samples influenced by air masses that had traveled over forested and populated areas. Oxidation products of long-chain (C 10-12) alkane precursors were detected during urban influence. Influence of Canadian wildfires resulted in increased numbers of identified sulfur-containing compounds and oligomeric species, including those formed through aqueous-phase reactions involving methylglyoxal. Light-absorbing aqueous-phase products of syringol and guaiacol oxidation were observed in the wildfire-influenced samples, and dinitroaromatic compounds were observed in all cloud water samples (wildfire, biogenic, and urban-influenced). Overall, the cloud water molecular composition depended on air mass source influence and reflected aqueous-phase reactions involving biogenic, urban, and biomass burning precursors.« less

Droplet Combustion Experiment on STS-94

NASA Technical Reports Server (NTRS)

2003-01-01

Fuel ignites and burns in the Droplet Combustion Experiment (DCE) on STS-94 on July 12, 1997, MET:11/07:00 (approximate). DCE used various fuels -- in drops ranging from 1 mm (0.04 inches) to 5 mm (0.2 inches) -- and mixtures of oxidizers and inert gases to learn more about the physics of combustion in the simplest burning configuration, a sphere. The DCE was designed to investigate the fundamental combustion aspects of single, isolated droplets under different pressures and ambient oxygen concentrations for a range of droplet sizes varying between 2 and 5 mm. The experiment elapsed time is shown at the bottom of the composite image. The DCE principal investigator was Forman Williams, University of California, San Diego. The experiment was part of the space research investigations conducted during the Microgravity Science Laboratory-1R mission (STS-94, July 1-17 1997). Advanced combustion experiments will be a part of investigations plarned for the International Space Station. (1.3MB, 13-second MPEG, screen 320 x 240 pixels; downlinked video, higher quality not available) A still JPG composite of this movie is available at http://mix.msfc.nasa.gov/ABSTRACTS/MSFC-0300170.html.