Chemical characterization, nano-particle mineralogy and particle size distribution of basalt dust wastes.

PubMed

Dalmora, Adilson C; Ramos, Claudete G; Oliveira, Marcos L S; Teixeira, Elba C; Kautzmann, Rubens M; Taffarel, Silvio R; de Brum, Irineu A S; Silva, Luis F O

2016-01-01

Understanding the geochemistry of basalt alteration is central to the study of agriculture systems. Various nano-minerals play an important role in the mobilization of contaminants and their subsequent uptake by plants. We present a new analytical experimental approach in combination with an integrated analytical protocol designed to study basalt alteration processes. Recently, throughout the world, ultra-fine and nano-particles derived from basalt dust wastes (BDW) during "stonemeal" soil fertilizer application have been of great concern for their possible adverse effects on human health and environmental pollution. Samples of BDW utilized were obtained from companies in the Nova Prata mining district in southern Brazil for chemical characterization and nano-mineralogy investigation, using an integrated application of advanced characterization techniques such as X-ray diffraction (XRD), High Resolution-Transmission Electron microscopy (HR-TEM)/Energy Dispersive Spectroscopy (EDS)/(selected-area diffraction pattern) SAED, Field Emission-Scanning Electron Microscopy (FE-SEM/EDS), and granulometric distribution analysis. The investigation has revealed that BDW materials are dominated by SiO2, Al2O3, and Fe2O3, with a complex micromineralogy including alkali feldspar, augite, barite, labradorite, hematite, heulandrite, gypsum, kaolinite, quartz, and smectite. In addition, we have identified a number of trace metals such as Cd, Cu, Cr, and Zn, that are preferentially concentrated into the finer, inhalable, dust fraction and, thus, could present a health hazard in the urban areas around the basalt mining zone. The implication of this observation is that use of these nanometric-sized particulates as soil fertilizer may present different health challenges to those of conventional fertilizers, inviting future work regarding the relative toxicities of these materials. Our investigation on the particle size distribution, nano-particle mineralogy and chemical composition in

Classification of Magnetic Nanoparticle Systems—Synthesis, Standardization and Analysis Methods in the NanoMag Project

PubMed Central

Bogren, Sara; Fornara, Andrea; Ludwig, Frank; del Puerto Morales, Maria; Steinhoff, Uwe; Fougt Hansen, Mikkel; Kazakova, Olga; Johansson, Christer

2015-01-01

This study presents classification of different magnetic single- and multi-core particle systems using their measured dynamic magnetic properties together with their nanocrystal and particle sizes. The dynamic magnetic properties are measured with AC (dynamical) susceptometry and magnetorelaxometry and the size parameters are determined from electron microscopy and dynamic light scattering. Using these methods, we also show that the nanocrystal size and particle morphology determines the dynamic magnetic properties for both single- and multi-core particles. The presented results are obtained from the four year EU NMP FP7 project, NanoMag, which is focused on standardization of analysis methods for magnetic nanoparticles. PMID:26343639

Membrane fouling by extracellular polymeric substances after ozone pre-treatment: Variation of nano-particles size.

PubMed

Yu, Wenzheng; Zhang, Dizhong; Graham, Nigel J D

2017-09-01

The application of ozone pre-treatment for ultrafiltration (UF) in drinking water treatment has been studied for more than 10 years, but its performance in mitigating or exacerbating membrane fouling has been inconclusive, and sometimes contradictory. To help explain this, our study considers the significance of the influent organic matter and its interaction with ozone on membrane fouling, using solutions of two representative types of extracellular polymeric substances (EPS), alginate and bovine serum albumin (BSA), and samples of surface water. The results show that at typical ozone doses there is no measurable mineralization of alginate and BSA, but substantial changes in their structure and an increase in the size of nano-particle aggregates (micro-flocculation). The impact of ozonation on membrane fouling, as indicated by the membrane flux, was markedly different for the two types of EPS and found to be related to the size of the nano-particle aggregates formed in comparison with the UF pore size. Thus, for BSA, ozonation created aggregate sizes similar to the UF pore size (100 k Dalton) which led to an increase in fouling. In contrast, ozonation of alginate created the nano-particle aggregates greater than the UF pore size, giving reduced membrane fouling/greater flux. For solutions containing a mixture of the two species of EPS the overall impact of ozonation on UF performance depends on the relative proportion of each, and the ozone dose, and the variable behaviour has been demonstrated by the surface water. These results provide new information about the role of nano-particle aggregate size in explaining the reported ambiguity over the benefits of applying ozone as pre-treatment for ultrafiltration. Copyright © 2017. Published by Elsevier Ltd.

Optical Detection and Sizing of Single Nano-Particles Using Continuous Wetting Films

PubMed Central

Hennequin, Yves; McLeod, Euan; Mudanyali, Onur; Migliozzi, Daniel; Ozcan, Aydogan; Dinten, Jean-Marc

2013-01-01

The physical interaction between nano-scale objects and liquid interfaces can create unique optical properties, enhancing the signatures of the objects with sub-wavelength features. Here we show that the evaporation on a wetting substrate of a polymer solution containing sub-micrometer or nano-scale particles creates liquid micro-lenses that arise from the local deformations of the continuous wetting film. These micro-lenses have properties similar to axicon lenses that are known to create beams with a long depth of focus. This enhanced depth of focus allows detection of single nanoparticles using a low magnification microscope objective lens, achieving a relatively wide field-of-view, while also lifting the constraints on precise focusing onto the object plane. Hence, by creating these liquid axicon lenses through spatial deformations of a continuous thin wetting film, we transfer the challenge of imaging individual nano-particles to detecting the light focused by these lenses. As a proof of concept, we demonstrate the detection and sizing of single nano-particles (100 and 200 nm), CpGV granuloviruses as well as Staphylococcus epidermidis bacteria over a wide field of view of e.g., 5.10×3.75 mm2 using a ×5 objective lens with a numerical aperture of 0.15. In addition to conventional lens-based microscopy, this continuous wetting film based approach is also applicable to lensfree computational on-chip imaging, which can be used to detect single nano-particles over a large field-of-view of e.g., >20-30 mm2. These results could be especially useful for high-throughput field-analysis of nano-scale objects using compact and cost-effective microscope designs. PMID:23889001

Modulation in magnetic exchange interaction, core shell structure and Hopkinson's peak with chromium substitution into Ni0.75Co0.25Fe2O4 nano particles

NASA Astrophysics Data System (ADS)

Uday Bhasker, S.; Choudary, G. S. V. R. K.; Reddy, M. V. Ramana

2018-05-01

The ever growing applications and ever evolving challenges of magnetic nano particles has been motivating the researchers from various disciplines towards this area of magnetic nano particles. Cation substitutional effect on the magnetic structure of the nanoparticles forms a crucial aspect in their applications. Here the environmentally benign auto combustion method was employed to synthesize chromium substituted nickel cobalt ferrite (Ni0.75Co0.25Fe2-xCrxO4; x = 0, 0.10, 0.15) nano particles, from aqueous metal nitrate solutions. Chromium substitution has shown its effect on the structural, magnetic and electrical properties of Ni0.75Co0.25Fe2O4. Structural and phase analysis of the prepared samples show increased phase purity of ferrite sample with increasing Cr substitution. The TEM (Transmission Electron Microscope) image confirms the nano size of the particles, EDS (Energy dispersive X-ray Spectroscopy) has supported the stoichiometry of the prepared samples and FTIR (Fourier-transform infrared spectroscopic) analysis confirms the spinel structure and also suggests cation redistributions with chromium substitution. VSM (Vibrational Sample Magnetometer) is used to study the magnetic properties through magnetic hysteresis (M-H) loop and magnetic Hopkinson effect. All samples show hysteresis and show reduction in magnetic properties with increase in chromium content. The thermo magnetic study shows Hopkinson peak(s) in the magnetization vs. temperature (M-T) graph and also shows variation in the nature of Hopkinson peak with chromium substitution. Possible reasons for the changes in the nature of the peak are discussed.

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

The role of particle size of particulate nano-zinc oxide wood preservatives on termite mortality and leach resistance

NASA Astrophysics Data System (ADS)

Clausen, Carol A.; Kartal, S. Nami; Arango, Rachel A.; Green, Frederick

2011-06-01

Historically most residential wood preservatives were aqueous soluble metal formulations, but recently metals ground to submicron size and dispersed in water to give particulate formulations have gained importance. In this study, the specific role nano-zinc oxide (ZnO) particle size and leach resistance plays in termite mortality resulting from exposure to particulate ZnO-treated wood was investigated. Southern yellow pine (SYP) sapwood impregnated with three concentrations of two particle sizes (30 and 70 nm) of ZnO were compared to wood treated with soluble zinc sulphate (ZnSO4) preservative for leach resistance and termite resistance. Less than four percent leached from the particulate nano-ZnO-treated specimens, while 13 to 25% of the zinc sulphate leached from the soluble treated wood. Nano-ZnO was essentially non-leachable from wood treated with 5% formulation for the 30-nm particle size. In a no-choice laboratory test, eastern subterranean termites ( Reticulitermes flavipes) consumed less than 10% of the leached nano-ZnO-treated wood with 93 to 100% mortality in all treatment concentrations. In contrast, termites consumed 10 to 12% of the leached ZnSO4-treated wood, but with lower mortality: 29% in the 1% treatment group and less than 10% (5 and 8%, respectively) in the group of wood blocks treated with 2.5 and 5.0% ZnSO4. We conclude that termites were repelled from consuming wood treated with nano-ZnO, but when consumed it was more toxic to eastern subterranean termites than wood treated with the soluble metal oxide formulation. There were no differences in leaching or termite mortality between the two particle sizes of nano-ZnO.

TRANSPORT AND DEPOSITION OF NANO-SIZE PARTICLES IN THE UPPER HUMAN RESPIRATORY AIRWAYS

EPA Science Inventory

TRANSPORT AND DEPOSITION OF NANO-SIZE PARTICLES IN THE UPPER HUMAN RESPIRATORY AIRWAYS. Zhe Zhang*, Huawei Shi, Clement Kleinstreuer, Department of Mechanical and Aerospace Engineering, North Carolina State University, Raleigh, NC 27695-7910; Chong S. Kim, National Health and En...

Nano-magnetic particles used in biomedicine: core and coating materials.

PubMed

Karimi, Z; Karimi, L; Shokrollahi, H

2013-07-01

Magnetic nanoparticles for medical applications have been developed by many researchers. Separation, immunoassay, drug delivery, magnetic resonance imaging and hyperthermia are enhanced by the use of suitable magnetic nanoparticles and coating materials in the form of ferrofluids. Due to their low biocompatibility and low dispersion in water solutions, nanoparticles that are used for biomedical applications require surface treatment. Various kinds of coating materials including organic materials (polymers), inorganic metals (gold, platinum) or metal oxides (aluminum oxide, cobalt oxide) have been attracted during the last few years. Based on the recent advances and the importance of nanomedicine in human life, this paper attempts to give a brief summary on the different ferrite nano-magnetic particles and coatings used in nanomedicine. Copyright © 2013 Elsevier B.V. All rights reserved.

Preparation of hemoglobin-loaded nano-sized particles with porous structure as oxygen carriers.

PubMed

Zhao, Jian; Liu, Chang-Sheng; Yuan, Yuan; Tao, Xin-Yi; Shan, Xiao-Qian; Sheng, Yan; Wu, Fan

2007-03-01

Hb (hemoglobin)-loaded particles (HbP) encapsulated by a biodegradable polymer used as oxygen carrier were prepared. A modified double emulsion and solvent diffusion/evaporation method was adopted. All experiments were performed based on two types of biodegradable polymers, poly(epsilon-caprolactone) (PCL) and poly(epsilon-caprolactone-ethylene glycol) (PCL-PEG). The biodistribution and the survival time in blood of the particles were investigated in a mouse model. Encapsulation efficiency and pore-connecting efficiency were evaluated by a novel sulfocyanate potassium method. The influence of process parameters on the particle size and pore-connecting efficiency (PCE%) of nanoparticles have been discussed. The prepared conditions: solvent, external aqueous phase, pressure were discussed. The system utilizing dichloromethane (DCM)/ethyl acetate (EA) as a solvent with an unsaturated external aqueous phase yielded the highest encapsulation efficiency (87.35%) with a small mean particle size (153 nm). The formation of porous channels was attributed to the diffusion of solvent. The PCE% was more sensitive to the rate of solvent diffusion that was obviously affected by the preparation temperature. The PCE% reached 87.47% when PCL-PEG was employed at 25 degrees C. P(50) of HbP was 27 mmHg, which does not seem to be greatly affected by the encapsulation procedure. In vivo, following intravenous injection of 6-coumarin labeled HbP, the major organ accumulating Hb-loaded particles was the liver. The half-life of nano-sized PCL HbP was 3.1 times as long as the micro-sized PCL HbP. Also, Nano-sized as well as a PEGylated surface on HbP is beneficial for prolonged blood residence (7.2 fold increase).

Enhancement of integrated photonic biosensing by magnetic controlled nano-particles

NASA Astrophysics Data System (ADS)

Peserico, N.; Sharma, P. Pratim; Belloni, A.; Damin, F.; Chiari, M.; Bertacco, R.; Melloni, A.

2018-02-01

Integrated Mach-Zehnder interferometers, ring resonators, Bragg reflectors or simple waveguides are commonly used as photonic biosensing elements. They can be used for label-free detection relating the changes in the optical signal in realtime, as optical power or spectral response, to the presence and even the quantity of a target analyte on the surface of the photonic waveguide. The label-free method has advantages in term of sample preparation but it is more sensitive to spurious effects such as temperature and refractive index sample variation, biological noise, etc. Label methods can be more robust, more sensitive and able to manipulate the biological targets. In this work, we present an innovative labeled biosensing technique exploiting magnetic nano-beads for enhancement of sensitivity over integrated optic microrings. A sandwich binding is exploited to bring the magnetic labels close to the surface of the optical waveguide and interact with the optical evanescent field. The proximity and the quantity of the magnetic nano-beads are seen as a shift in the resonance of the microring. Detection of antibodies permits to reach a high level of sensitivity, down to 8 pM with a high confidence level. The sizes of the nano-beads are 50 to 250 nm. Furthermore, time-varying magnetic fields permit to manipulate the beads and even induce specific signals on the detected light to easy the processing and provide a reliable identification of the presence of the desired analyte. Multiple analytes detection is also possible.

Synthesis, structural, dielectric and magnetic properties of polyol assisted copper ferrite nano particles

NASA Astrophysics Data System (ADS)

Pavithradevi, S.; Suriyanarayanan, N.; Boobalan, T.

2017-03-01

Nanocrystalline copper ferrite CuFe2O4 is synthesized by co-precipitation method in ethylene glycol as chelating agent, using sodium Hydroxide as precipitator at pH 8. The as synthesized CuFe2O4 is annealed at temperatures of 350 °C, 700 °C, and 1050 °C for 2 h respectively. The thermal analysis of the synthesized sample is done by TG technique. It is shown that at 260 °C ethylene glycol has evaporated completely and after 715 °C, spinel ferrite is formed with a cubic structure. The calculated lattice parameters are in agreement with the reported values. FTIR spectra of CuFe2O4 nano particles are as synthesized and annealed at 1050 °C and recorded between 400 cm-1 and 4000 cm-1. It shows that when the temperature increases ethylene glycol gradually evaporates. Finally, nano crystalline single phase spinel ferrite is obtained. X-ray diffraction (XRD) and electron diffraction (EDS) studies show that the sample is indexed as the face centered cubic spinel structure. Scanning electron microscopy (SEM) and transmission electron microscopy (TEM) indicated that the particles are flaky and spherical with the crystallite size in the range of 25-34 nm. From the dielectric studies, the dielectric constant decreases as the frequency increases. Low value of dielectric loss at higher frequencies suggests that the material is suitable for high frequency applications. AC conductivity increases with frequency. The magnetic properties of the samples are measured using a vibrating sample magnetometer (VSM) at room temperature, which shows that the sample exhibited a typical super paramagnetic behavior at low temperature. The saturation magnetization, remanant magnetism, and coercivity increases with applied field.

Synthesis and characterization of magnetic and non-magnetic core-shell polyepoxide micrometer-sized particles of narrow size distribution.

PubMed

Omer-Mizrahi, Melany; Margel, Shlomo

2009-01-15

Core polystyrene microspheres of narrow size distribution were prepared by dispersion polymerization of styrene in a mixture of ethanol and 2-methoxy ethanol. Uniform polyglycidyl methacrylate/polystyrene core-shell micrometer-sized particles were prepared by emulsion polymerization at 73 degrees C of glycidyl methacrylate in the presence of the core polystyrene microspheres. Core-shell particles with different properties (size, surface morphology and composition) have been prepared by changing various parameters belonging to the above seeded emulsion polymerization process, e.g., volumes of the monomer glycidyl methacrylate and the crosslinker monomer ethylene glycol dimethacrylate. Magnetic Fe(3)O(4)/polyglycidyl methacrylate/polystyrene micrometer-sized particles were prepared by coating the former core-shell particles with magnetite nanoparticles via a nucleation and growth mechanism. Characterization of the various particles has been accomplished by routine methods such as light microscopy, SEM, FTIR, BET and magnetic measurements.

Preparation and magnetic properties of nano size nickel ferrite particles using hydrothermal method

PubMed Central

2012-01-01

Background Nickel ferrite, a kind of soft magnetic materials is one of the most attracting class of materials due to its interesting and important properties and has many technical applications, such as in catalysis, sensors and so on. In this paper the synthesis of NiFe2O4 nanoparticles by the hydrothermal method is reported and the inhibition of surfactant (Glycerol or Sodium dodecyl sulfate) on the particles growth is investigated. Methods For investigation of the inhibition effect of surfactant on NiFe2O4 particles growth, the samples were prepared in presence of Glycerol and Sodium dodecyl sulfate. The X-ray powder diffraction (XRD), transmission electron microscopy (TEM), Fourier transform infrared spectroscopy (FT-IR), vibrating sample magnetometer (VSM) and inductively coupled plasma atomic emission spectrometer (ICP-AES) techniques were used to characterize the samples. Results The results of XRD and ICP-AES show that the products were pure NiFe2O4 and also nanoparticles grow with increasing the temperature, while surfactant prevents the particle growth under the same condition. The average particle size was determined from the Scherrer's equation and TEM micrographs and found to be in the range of 50-60 nm that decreased up to 10-15 nm in presence of surfactant. The FT-IR results show two absorption bands near to 603 and 490 cm-1 for the tetrahedral and octahedral sites respectively. Furthermore, the saturated magnetization and coercivity of NiFe2O4 nanoparticles were in the range of 39.60 emu/g and 15.67 Qe that decreased for samples prepared in presence of surfactant. As well as, the nanoparticles exhibited a superparamagnetic behavior at room temperature. Conclusions Nanosized nickel ferrite particles were synthesized with and without surfactant assisted hydrothermal methods. The results show that with increasing of temperature, the crystallinity of nanoparticles is increased. In the presence of surfactants, the crystallinity of NiFe2O4 nanoparticles

Preparation and magnetic properties of nano size nickel ferrite particles using hydrothermal method.

PubMed

Nejati, Kamellia; Zabihi, Rezvanh

2012-03-30

Nickel ferrite, a kind of soft magnetic materials is one of the most attracting class of materials due to its interesting and important properties and has many technical applications, such as in catalysis, sensors and so on. In this paper the synthesis of NiFe2O4 nanoparticles by the hydrothermal method is reported and the inhibition of surfactant (Glycerol or Sodium dodecyl sulfate) on the particles growth is investigated. For investigation of the inhibition effect of surfactant on NiFe2O4 particles growth, the samples were prepared in presence of Glycerol and Sodium dodecyl sulfate. The X-ray powder diffraction (XRD), transmission electron microscopy (TEM), Fourier transform infrared spectroscopy (FT-IR), vibrating sample magnetometer (VSM) and inductively coupled plasma atomic emission spectrometer (ICP-AES) techniques were used to characterize the samples. The results of XRD and ICP-AES show that the products were pure NiFe2O4 and also nanoparticles grow with increasing the temperature, while surfactant prevents the particle growth under the same condition. The average particle size was determined from the Scherrer's equation and TEM micrographs and found to be in the range of 50-60 nm that decreased up to 10-15 nm in presence of surfactant. The FT-IR results show two absorption bands near to 603 and 490 cm-1 for the tetrahedral and octahedral sites respectively. Furthermore, the saturated magnetization and coercivity of NiFe2O4 nanoparticles were in the range of 39.60 emu/g and 15.67 Qe that decreased for samples prepared in presence of surfactant. As well as, the nanoparticles exhibited a superparamagnetic behavior at room temperature. Nanosized nickel ferrite particles were synthesized with and without surfactant assisted hydrothermal methods. The results show that with increasing of temperature, the crystallinity of nanoparticles is increased. In the presence of surfactants, the crystallinity of NiFe2O4 nanoparticles decreased in comparison with surfactant

Synthesis, characterization and magnetic behavior of Co/MCM-41 nano-composites

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

Cuello, N.; Elías, V.; CONICET

2013-09-15

Synthesis, structure and magnetic properties of Co/MCM-41 as magnetic nano-composites have been investigated. Mesoporous materials with different degrees of metal loading were prepared by wet impregnation and characterized by ICP, XRD, N{sub 2} adsorption, UV–vis DRS, TPR and EPMA-EDS. Cobalt oxide clusters and Co{sub 3}O{sub 4} nano-particles could be confined inside the mesopores of MCM-41, being this fact favored by the Co loading increasing. In addition, larger crystals of Co{sub 3}O{sub 4} detectable by XRD also grow on the surface when the Co loading is enhanced. The magnetic characterization was performed in a SQUID magnetometer using a maximum magnetic appliedmore » field µ{sub 0}Ha=1 T. While the samples with the higher Co loadings showed a behavior typically paramagnetic, a superparamagnetic contribution is more notorious for lower loadings, suggesting high Co species dispersion. - Graphical abstract: Room temperature hysteresis loops as a function of the Co content. Display Omitted - Highlights: • Co species as isolated Co{sup 2+}, oxide clusters and Co{sub 3}O{sub 4} nano-particles were detected. • For higher Co loads were detected, by XRD, Co{sub 3}O{sub 4} particles on the external surface. • The confining of Co species inside the mesopores was achieved by increasing Co load. • Paramagnetism from oxide clusters/nano-particles becomes dominant for higher Co loads. • Superparamagnetism can be assigned to Co species of small size and finely dispersed.« less

Temperature dependent and applied field strength dependent magnetic study of cobalt nickel ferrite nano particles: Synthesized by an environmentally benign method

NASA Astrophysics Data System (ADS)

Sontu, Uday Bhasker; G, Narsinga Rao; Chou, F. C.; M, V. Ramana Reddy

2018-04-01

Spinel ferrites have come a long way in their versatile applications. The ever growing applications of these materials demand detailed study of material properties and environmental considerations in their synthesis. In this article, we report the effect of temperature and applied magnetic field strength on the magnetic behavior of the cobalt nickel ferrite nano powder samples. Basic structural properties of spinel ferrite nano particles, that are synthesized by an environmentally benign method of auto combustion, are characterized through XRD, TEM, RAMAN spectroscopy. Diffuse Reflectance Spectroscopy (DRS) is done to understand the nickel substitution effect on the optical properties of cobalt ferrite nano particles. Thermo magnetic studies using SQUID in the temperature range 5 K to 400 K and room temperature (300 K) VSM studies are performed on these samples. Fields of 0Oe (no applied field: ZF), 1 kOe (for ZFC and FC curves), 5 kOe (0.5 T), 50 kOe (5T) (for M-H loop study) are used to study the magnetic behavior of these nano particles. The XRD,TEM analysis suggest 40 nm crystallites that show changes in the cation distribution and phase changes in the spinel structure with nickel substitution. Raman micrographs support phase purity changes and cation redistributions with nickel substitution. Diffuse reflectance study on powder samples suggests two band gap values for nickel rich compounds. The Magnetic study of these sample nano particles show varied magnetic properties from that of hard magnetic, positive multi axial anisotropy and single-magnetic-domain structures at 5 K temperature to soft magnetic core shell like structures at 300 K temperature. Nickel substitution effect is non monotonous. Blocking temperature of all the samples is found to be higher than the values suggested in the literature.

Validation of a particle tracking analysis method for the size determination of nano- and microparticles

NASA Astrophysics Data System (ADS)

Kestens, Vikram; Bozatzidis, Vassili; De Temmerman, Pieter-Jan; Ramaye, Yannic; Roebben, Gert

2017-08-01

Particle tracking analysis (PTA) is an emerging technique suitable for size analysis of particles with external dimensions in the nano- and sub-micrometre scale range. Only limited attempts have so far been made to investigate and quantify the performance of the PTA method for particle size analysis. This article presents the results of a validation study during which selected colloidal silica and polystyrene latex reference materials with particle sizes in the range of 20 nm to 200 nm were analysed with NS500 and LM10-HSBF NanoSight instruments and video analysis software NTA 2.3 and NTA 3.0. Key performance characteristics such as working range, linearity, limit of detection, limit of quantification, sensitivity, robustness, precision and trueness were examined according to recommendations proposed by EURACHEM. A model for measurement uncertainty estimation following the principles described in ISO/IEC Guide 98-3 was used for quantifying random and systematic variations. For nominal 50 nm and 100 nm polystyrene and a nominal 80 nm silica reference materials, the relative expanded measurement uncertainties for the three measurands of interest, being the mode, median and arithmetic mean of the number-weighted particle size distribution, varied from about 10% to 12%. For the nominal 50 nm polystyrene material, the relative expanded uncertainty of the arithmetic mean of the particle size distributions increased up to 18% which was due to the presence of agglomerates. Data analysis was performed with software NTA 2.3 and NTA 3.0. The latter showed to be superior in terms of sensitivity and resolution.

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.

Effect of size on bulk and surface cohesion energy of metallic nano-particles

NASA Astrophysics Data System (ADS)

Yaghmaee, M. S.; Shokri, B.

2007-04-01

The knowledge of nano-material properties not only helps us to understand the extreme behaviour of small-scale materials better (expected to be different from what we observe from their bulk value) but also helps us to analyse and design new advanced functionalized materials through different nano technologies. Among these fundamental properties, the cohesion (binding) energy mainly describes most behaviours of materials in different environments. In this work, we discuss this fundamental property through a nano-thermodynamical approach using two algorithms, where in the first approach the size dependence of the inner (bulk) cohesion energy is studied, and in the second approach the surface cohesion energy is considered too. The results, which are presented through a computational demonstration (for four different metals: Al, Ga, W and Ag), can be compared with some experimental values for W metallic nano-particles.

Exposure to nano-size titanium dioxide causes oxidative damages in human mesothelial cells: The crystal form rather than size of particle contributes to cytotoxicity.

PubMed

Hattori, Kenji; Nakadate, Kazuhiko; Morii, Akane; Noguchi, Takumi; Ogasawara, Yuki; Ishii, Kazuyuki

2017-10-14

Exposure to nanoparticles such as carbon nanotubes has been shown to cause pleural mesothelioma similar to that caused by asbestos, and has become an environmental health issue. Not only is the percutaneous absorption of nano-size titanium dioxide particles frequently considered problematic, but the possibility of absorption into the body through the pulmonary route is also a concern. Nevertheless, there are few reports of nano-size titanium dioxide particles on respiratory organ exposure and dynamics or on the mechanism of toxicity. In this study, we focused on the morphology as well as the size of titanium dioxide particles. In comparing the effects between nano-size anatase and rutile titanium dioxide on human-derived pleural mesothelial cells, the anatase form was shown to be actively absorbed into cells, producing reactive oxygen species and causing oxidative damage to DNA. In contrast, we showed for the first time that the rutile form is not easily absorbed by cells and, therefore, does not cause oxidative DNA damage and is significantly less damaging to cells. These results suggest that with respect to the toxicity of titanium dioxide particles on human-derived mesothelial cells, the crystal form rather than the particle size has a greater effect on cellular absorption. Also, it was indicated that the difference in absorption is the primary cause of the difference in the toxicity against mesothelial cells. Copyright © 2017 Elsevier Inc. All rights reserved.

Magnetic Particles Coupled to Disposable Screen Printed Transducers for Electrochemical Biosensing

PubMed Central

Yáñez-Sedeño, Paloma; Campuzano, Susana; Pingarrón, José M.

2016-01-01

Ultrasensitive biosensing is currently a growing demand that has led to the development of numerous strategies for signal amplification. In this context, the unique properties of magnetic particles; both of nano- and micro-size dimensions; have proved to be promising materials to be coupled with disposable electrodes for the design of cost-effective electrochemical affinity biosensing platforms. This review addresses, through discussion of selected examples, the way that nano- and micro-magnetic particles (MNPs and MMPs; respectively) have contributed significantly to the development of electrochemical affinity biosensors, including immuno-, DNA, aptamer and other affinity modes. Different aspects such as type of magnetic particles, assay formats, detection techniques, sensitivity, applicability and other relevant characteristics are discussed. Research opportunities and future development trends in this field are also considered. PMID:27681733

Synthesis and characterization of monosodium urate (MSU) nano particles

NASA Astrophysics Data System (ADS)

Tank, Nirali S.; Rathod, K. R.; Parekh, B. B.; Parikh, K. D.; Joshi, M. J.

2016-05-01

In Gout the deposition of crystals of Monosodium Urate (MSU) in various connective tissues and joints occurs, which is very painful with immflamation. The deposition likely to begin with nano particles form and expected to grow in to micro-paricles and hence it is important to synthesize and characrterize MSU nano-particles. The MSU nano particles were synthesized by wet chemical method using NaOH and uric acid (C5H4N4O3) and then characterized by powder XRD, TEM, FT-IR and thermal analysis. From the powder XRD the triclinic structure was found and 40 nm average particle size was estimated by using Scherrer's formula. From TEM the particle size was found to be in the range of 20 to 60 nm. The FT-IR spectrum for the MSU nano particles confirmed the presence of O-H stretching, N-H stretching, N-H rocking, C = O, C = C Enol or Keto and C = N vibrations. The thermal analysis was carried out from room temperature to 900°C. With comparison to the bulk MSU the thermal stability of MSU nano particles was slightly higher and 1.5 water molecules were found to be associated with MSU nano particles. Present results are compared with the bulk MSU.

Synthesis and characterization of struvite nano particles

NASA Astrophysics Data System (ADS)

Rathod, K. R.; Jogiya, B. V.; Chauhan, C. K.; Joshi, M. J.

2015-06-01

Struvite, Ammonium Magnesium Phosphate Hexahydrate [(AMPH) - (NH4)MgPO4.6(H2O)], is one of the fascinating inorganic phosphate minerals. Struvite is one of the components of the urinary stones. Struvite occurs as crystallites in urine and grows as a type of kidney stone. In this study, struvite nano particles were synthesized by wet chemical technique. The aqueous solutions containing dissolved Mg(CH3COO)2.4H2O and (NH4)H2PO4 mixed at the Mg/P molar ratio of 1.00. The synthesized struvite nano particles were characterized by XRD, FT-IR, Thermal Analysis and TEM. From XRD, crystal structure of the nano particle was found to be orthorhombic and crystalline size was found to be within 11 to 26 nm. The FT-IR spectrum for the struvite nano particles confirmed the presence of a water molecule and metal-oxygen stretching vibration, O-H stretching and bending, N-H bending and stretching, P-O bending and stretching vibrations. The Thermal Analysis was carried out from room temperature to 900°C. From TEM analysis, particle size was 23 to 30 nm. All the results were compared with bulk struvite.

Magnetic bead detection using nano-transformers.

PubMed

Kim, Hyung Kwon; Hwang, Jong Seung; Hwang, Sung Woo; Ahn, Doyeol

2010-11-19

A novel scheme to detect magnetic beads using a nano-scale transformer with a femtoweber resolution is reported. We have performed a Faraday's induction experiment with the nano-transformer at room temperature. The transformer shows the linear output voltage responses to the sinusoidal input current. When magnetic beads are placed on the transformer, the output responses are increased by an amount corresponding to the added magnetic flux from the beads when compared with the case of no beads on the transformer. In this way, we could determine whether magnetic beads are on top of the transformer in a single particle level.

Exposure assessment of nano-sized and respirable particles at different workplaces

NASA Astrophysics Data System (ADS)

Tsai, Chuen-Jinn; Huang, Cheng-Yu; Chen, Sheng-Chieh; Ho, Chi-En; Huang, Cheng-Hsiung; Chen, Chun-Wan; Chang, Cheng-Ping; Tsai, Su-Jung; Ellenbecker, Michael J.

2011-09-01

In this study, nanoparticle (NP, diameter < 100 nm) and respirable particles measurements were conducted at three different nanopowder workplaces, including the mixing area of a nano-SiO2-epoxy molding compound plant (primary diameter: 15 nm), bagging areas of a nano-carbon black (nano-CB) (primary diameter: 32 nm) and a nano-CaCO3 (primary diameter: 94 nm) manufacturing plant. Chemical analysis of respirable particle mass (RPM) and NPs was performed to quantify the content of manufactured nanoparticles in the collected samples. Nanopowder products obtained from the plants were used in the laboratory dustiness testing using a rotating drum tester to obtain particle mass and number distributions. The obtained laboratory data were then used to elucidate the field data. Both field and laboratory data showed that NP number and mass concentrations of manufactured materials were close to the background level. Number concentration was elevated only for particles with the electrical mobility diameter >100 nm during bagging or feeding processes, unless there were combustion-related incidental sources existed. Large fraction of nanomaterials was found in the RPM due to agglomeration of nanomaterials or attachment of nanomaterials to the larger particles. From this study, it is concluded that RPM concentration measurements are necessary for the exposure assessment of nanoparticles in workplaces.

The Behaviors of Ferro-Magnetic Nano-Particles In and Around Blood Vessels under Applied Magnetic Fields

PubMed Central

Nacev, A.; Beni, C.; Bruno, O.; Shapiro, B.

2010-01-01

In magnetic drug delivery, therapeutic magnetizable particles are typically injected into the blood stream and magnets are then used to concentrate them to disease locations. The behavior of such particles in-vivo is complex and is governed by blood convection, diffusion (in blood and in tissue), extravasation, and the applied magnetic fields. Using physical first-principles and a sophisticated vessel-membrane-tissue (VMT) numerical solver, we comprehensively analyze in detail the behavior of magnetic particles in blood vessels and surrounding tissue. For any blood vessel (of any size, depth, and blood velocity) and tissue properties, particle size and applied magnetic fields, we consider a Krogh tissue cylinder geometry and solve for the resulting spatial distribution of particles. We find that there are three prototypical behaviors (blood velocity dominated, magnetic force dominated, and boundary-layer formation) and that the type of behavior observed is uniquely determined by three non-dimensional numbers (the magnetic-Richardson number, mass Péclet number, and Renkin reduced diffusion coefficient). Plots and equations are provided to easily read out which behavior is found under which circumstances (Figures 5, 6, 7, and 8). We compare our results to previously published in-vitro and in-vivo magnetic drug delivery experiments. Not only do we find excellent agreement between our predictions and prior experimental observations, but we are also able to qualitatively and quantitatively explain behavior that was previously not understood. PMID:21278859

Mixing of nanosize particles by magnetically assisted impaction techniques

NASA Astrophysics Data System (ADS)

Scicolone, James V.

Nanoparticles and nanocomposites offer unique properties that arise from their small size, large surface area, and the interactions of phases at their interfaces, and are attractive for their potential to improve performance of drugs, biomaterials, catalysts and other high-value-added materials. However, a major problem in utilizing nanoparticles is that they often lose their high surface area due to grain growth. Creating nanostructured composites where two or more nanosized constituents are intimately mixed can prevent this loss in surface area, but in order to obtain homogeneous mixing, de-agglomeration of the individual nanoparticle constituents is necessary. Due to high surface area, nano-particles form very large, fractal agglomerates. The structure of these agglomerates can have a large agglomerate composed of sub-agglomerates (SA), which itself consists of primary agglomerates (PA), that contain chain or net like nano-particle structures; typically sub-micron size. Thus the final agglomerate has a hierarchical, fractal structure, and depending upon the forces applied, it could break down to a certain size scale. The agglomerates can be fairly porous and fragile or they could be quite dense, based on primary particle size and its surface energy. Thus depending upon the agglomerate strength at different length scales, one could achieve deagglomeration and subsequent mixing at varying length scale. A better understanding of this can have a major impact on the field of nano-structured materials; thus the long term objective of this project is to gain fundamental understanding of deagglomeration and mixing of nano-agglomerates. Dry mixing is in general not effective in achieving desired mixing at nanoscale, whereas wet mixing suffers from different disadvantages like nanomaterial of interest should be insoluble, has to wet the liquid, and involves additional steps of filtration and drying. This research examines the use of environmentally friendly a novel

Cysteine-Functionalized Chitosan Magnetic Nano-Based Particles for the Recovery of Light and Heavy Rare Earth Metals: Uptake Kinetics and Sorption Isotherms

PubMed Central

Galhoum, Ahmed A.; Mafhouz, Mohammad G.; Abdel-Rehem, Sayed T.; Gomaa, Nabawia A.; Atia, Asem A.; Vincent, Thierry; Guibal, Eric

2015-01-01

Cysteine-functionalized chitosan magnetic nano-based particles were synthesized for the sorption of light and heavy rare earth (RE) metal ions (La(III), Nd(III) and Yb(III)). The structural, surface, and magnetic properties of nano-sized sorbent were investigated by elemental analysis, FTIR, XRD, TEM and VSM (vibrating sample magnetometry). Experimental data show that the pseudo second-order rate equation fits the kinetic profiles well, while sorption isotherms are described by the Langmuir model. Thermodynamic constants (ΔG°, ΔH°) demonstrate the spontaneous and endothermic nature of sorption. Yb(III) (heavy RE) was selectively sorbed while light RE metal ions La(III) and Nd(III) were concentrated/enriched in the solution. Cationic species RE(III) in aqueous solution can be adsorbed by the combination of chelating and anion-exchange mechanisms. The sorbent can be efficiently regenerated using acidified thiourea. PMID:28347004

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.

Influence of Poly (Ethylene Glycol) and Oleylamine on the Formation of Nano to Micron Size Spherical SiO2 Particles

EPA Science Inventory

We report an eco-friendly synthesis of well–controlled, nano-to-micron-size, spherical SiO2 particles using non-hazardous solvent and a byproducts-producing system. It was found that the morphology and size of spherical SiO2 particles are controlled by adjusting the concentration...

Enhanced sun protection of nano-sized metal oxide particles over conventional metal oxide particles: an in vitro comparative study.

PubMed

Singh, P; Nanda, A

2014-06-01

A systematic and detailed study has been designed and conducted, taking into account some of the proposed benefits such as increased efficiency, transparency, unique texture, protection of active ingredient and higher consumer compliance of cosmetics containing nano-sized metal oxides. This study also presents an in vitro method to determine sun protection factor of the investigational sunscreen cream samples containing zinc oxide and titanium dioxide with a varied range of particle size. Finally, a comparative study has been conducted between metal oxide particles, conventional as well as nanoparticles. All the skin cosmetics formulated were thermally stable with a pH ranging from 7.9 to 8.2. Moreover, the fatty acid substance content and residue were found to be analogous to the standard values in each skin cosmetic. The skin cosmetics containing the titanium or zinc oxide nanoparticles were found to have improved spreadability as compared to skin cosmetics containing conventional titanium or zinc oxide particles, respectively. All skin cosmetics were found to have uniform distribution of the particles. The sunscreen creams containing zinc oxide nanoparticles and titanium dioxide nanoparticles were found to have higher in vitro sun protection factor (SPF of 3.65 for ZnO nanoparticles and 4.93 for TiO2 nanoparticles) as compared to that of sunscreen creams containing conventional zinc oxide particles (SPF = 2.90) and conventional titanium dioxide (SPF = 1.29), clearly indicating the effect of reduction in particles size, from micro to nano, on the sun protection factor. Good texture, better spreadability and enhanced in vitro SPF proved the advantageous role of nanoparticles in cosmetics. © 2014 Society of Cosmetic Scientists and the Société Française de Cosmétologie.

Grafting of allylimidazole and n-vinylcaprolactam as a thermosensitive polymer onto magnetic nano-particles for the extraction and determination of celecoxib in biological samples.

PubMed

Morovati, Atefeh; Ahmad Panahi, Homayon; Yazdani, Farzaneh

2016-11-20

In this research, a novel method is reported for the surface grafting of n-vinylcaprolactam as a thermosensitive agent and allylimidazole with affinity toward celecoxib onto magnetic nano-particles. The grafted nano-particles were characterized by Fourier transform infrared spectroscopy, elemental analysis, and thermogravimetric analysis. The surface morphology was studied using Scanning Electron Microscopy. The resulting grafted nano-particles were used for the determination of trace celecoxib in biological human fluids and pharmaceutical samples. The profile of celecoxib uptake by the modified magnetic nano-particles indicated good accessibility of the active sites in the grafted copolymer. It was found that the adsorption behavior could be fitted by the Langmuir adsorption isotherm model. Solid phase extraction for biological fluids such as urine and serum were investigated. In this study, urine extraction recovery of more than 95% was obtained. Copyright © 2016 Elsevier B.V. All rights reserved.

A high gradient and strength bioseparator with nano-sized immunomagnetic particles for specific separation and efficient concentration of E. coli O157:H7

NASA Astrophysics Data System (ADS)

Lin, Jianhan; Li, Min; Li, Yanbin; Chen, Qi

2015-03-01

Sample pretreatment is a key to rapid screening of pathogens for prevention and control of foodborne diseases. Magnetic immunoseparation is a specific method based on antibody-antigen reaction to capture the target bacteria and concentrate them in a smaller-volume buffer. The use of nano-sized magnetic particles could improve the separation efficiency of bacteria but require much higher gradient and strength magnetic field. In this study, a strong magnetic bioseparator with a mean field strength of 1.35 T and a mean gradient of 90 T/m was developed with the use of the 30 nm and 180 nm magnetic particles to specifically separate and efficiently concentrate foodborne bacterial pathogens using Escherichia coli O157:H7 as a model bacterium. The polyclonal antibodies against E. coli were evaluated using Dot ELISA analysis for their good affinity with the target bacteria and then used to modify the surface of the magnetic nanoparticles by 1-(3-Dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride (EDC·HCl) method and streptavidin-biotin binding. The magnetic particle concentrations were optimized to be 40 μg/ml and 100 μg/ml for the 30 nm and 180 nm particles, respectively, the immunoreaction time was optimized to be 45 min for both sizes of particles, and the separation times were optimized to be 60 min and 2 min for the 30 nm and 180 nm particles, respectively. The total magnetic separation time was 2 h and 1 h for the 30 nm and 180 nm particles, respectively. The experimental results demonstrated that the bioseparator with the use of either 30 nm or 180 nm immunomagnetic particles could achieve a separation efficiency of >90% for E. coli O157:H7 at the concentrations ranging from 102 to 105 cfu/ml. No obvious interferences from non-target foodborne pathogens, such as SalmonellaTyphimurium and Listeria innocua, were found. For overall consideration of the consuming time, the cost, and the separation efficiency, the 180 nm magnetic particles are practical for rapid

Size-tunable drug-delivery capsules composed of a magnetic nanoshell.

PubMed

Fuchigami, Teruaki; Kitamoto, Yoshitaka; Namiki, Yoshihisa

2012-01-01

Nano-sized FePt capsules with two types of ultrathin shell were fabricated using a template method for use in a nano-scale drug delivery system. One capsule was composed of an inorganic-organic hybrid shell of a water-soluble polymer and FePt nanoparticles, and the other capsule was composed of a network of fused FePt nanoparticles. We demonstrated that FePt nanoparticles selectively accumulated on the polymer molecules adsorbed on the template silica particles, and investigated the morphologies of the particle accumulation by changing the concentration of the polymer solution with which the template particles were treated. Capsular size was reduced from 340 to less than 90 nm by changing the size of the silica template particles, and the shell thickness was controlled by changing the amount of FePt nanoparticles adsorbed on the template particles. The hybrid shell was maintained by the connection of FePt nanoparticles and polymer molecules, and the shell thickness was 10 nm at the maximum. The FePt network shell was fabricated by hydrothermal treatment of the FePt/polymer-modified silica composite particles. The FePt network shell was produced from only the FePt alloy, and the shell thickness was 3 nm. Water-soluble anti-cancer drugs could be loaded into the hollow space of FePt network capsules, and lipid-coated FePt network capsules loaded with anti-cancer drugs showed cellular toxicity. The nano-sized capsular structure and the ultrathin shell suggest applicability as a drug carrier in magnetically guided drug delivery systems.

Size-tunable drug-delivery capsules composed of a magnetic nanoshell

PubMed Central

Fuchigami, Teruaki; Kitamoto, Yoshitaka; Namiki, Yoshihisa

2012-01-01

Nano-sized FePt capsules with two types of ultrathin shell were fabricated using a template method for use in a nano-scale drug delivery system. One capsule was composed of an inorganic-organic hybrid shell of a water-soluble polymer and FePt nanoparticles, and the other capsule was composed of a network of fused FePt nanoparticles. We demonstrated that FePt nanoparticles selectively accumulated on the polymer molecules adsorbed on the template silica particles, and investigated the morphologies of the particle accumulation by changing the concentration of the polymer solution with which the template particles were treated. Capsular size was reduced from 340 to less than 90 nm by changing the size of the silica template particles, and the shell thickness was controlled by changing the amount of FePt nanoparticles adsorbed on the template particles. The hybrid shell was maintained by the connection of FePt nanoparticles and polymer molecules, and the shell thickness was 10 nm at the maximum. The FePt network shell was fabricated by hydrothermal treatment of the FePt/polymer-modified silica composite particles. The FePt network shell was produced from only the FePt alloy, and the shell thickness was 3 nm. Water-soluble anti-cancer drugs could be loaded into the hollow space of FePt network capsules, and lipid-coated FePt network capsules loaded with anti-cancer drugs showed cellular toxicity. The nano-sized capsular structure and the ultrathin shell suggest applicability as a drug carrier in magnetically guided drug delivery systems. PMID:23507895

Nano polypeptide particles reinforced polymer composite fibers.

PubMed

Li, Jiashen; Li, Yi; Zhang, Jing; Li, Gang; Liu, Xuan; Li, Zhi; Liu, Xuqing; Han, Yanxia; Zhao, Zheng

2015-02-25

Because of the intensified competition of land resources for growing food and natural textile fibers, there is an urgent need to reuse and recycle the consumed/wasted natural fibers as regenerated green materials. Although polypeptide was extracted from wool by alkaline hydrolysis, the size of the polypeptide fragments could be reduced to nanoscale. The wool polypeptide particles were fragile and could be crushed down to nano size again and dispersed evenly among polymer matrix under melt extrusion condition. The nano polypeptide particles could reinforce antiultraviolet capability, moisture regain, and mechanical properties of the polymer-polypeptide composite fibers.

Effect of cobalt doping on crystallinity, stability, magnetic and optical properties of magnetic iron oxide nano-particles

NASA Astrophysics Data System (ADS)

Anjum, Safia; Tufail, Rabia; Rashid, Khalid; Zia, Rehana; Riaz, S.

2017-06-01

This paper is dedicated to investigate the effect of Co2+ ions in magnetite Fe3O4 nano-particles with stoichiometric formula CoxFe3-xO4 where (x = 0, 0.05, 0.1 and 0.15) prepared by co-precipitation method. The structural, thermal, morphological, magnetic and optical properties of magnetite and Co2+ doped magnetite nanoparticles have been carried out using X-ray Diffractometer, Fourier Transform Infrared Spectroscopy, Themogravimetric Analysis, Scanning Electron Microscopy, Vibrating Sample Magnetometer (VSM) and UV-Vis Spectrometer (UV-Vis) respectively. Structural analysis verified the formation of single phase inverse spinel cubic structure with decrease in lattice parameters due to increase in cobalt content. FTIR analysis confirms the single phase of CoxFe3-xO4 nanoparticles with the major band at 887 cm-1, which might be due to the stretching vibrations of metal-oxide bond. The DSC results corroborate the finding of an increase in the maghemite to hematite phase transition temperature with increase in Co2+ content. The decrease in enthalpy with increase in Co2+ concentration attributed to the fact that the degree of conversion from maghemite to hematite decrease which shows that the stability increases with increasing Co2+ content in B-site of Fe3O4 structure. SEM analysis demonstrated the formation of spherical shaped nanoparticles with least agglomeration. The magnetic measurements enlighten that the coercivity and anisotropy of CoxFe3-xO4 nanoparticles are significantly increased. From UV-Vis analysis it is revealed that band gap energy increases with decreasing particle size. This result has a great interest for magnetic fluid hyperthermia application (MPH).

Modulation of mesenchymal stem cell behavior by nano- and micro-sized β-tricalcium phosphate particles in suspension and composite structures

NASA Astrophysics Data System (ADS)

Smoak, Mollie; Hogan, Katie; Kriegh, Lisa; Chen, Cong; Terrell, LeKeith B.; Qureshi, Ammar T.; Todd Monroe, W.; Gimble, Jeffrey M.; Hayes, Daniel J.

2015-04-01

Interest has grown in the use of microparticles and nanoparticles for modifying the mechanical and biological properties of synthetic bone composite structures. Micro- and nano-sized calcium phosphates are of interest for their osteoinductive behavior. Engineered composites incorporating polymers and ceramics, such as poly-l-lactic acid (PLLA) and beta-tricalcium phosphate (β-TCP), for bone tissue regeneration have been well investigated for their proliferative and osteoinductive abilities. Only limited research has been done to investigate the effects of different sizes of β-TCP particles on human mesenchymal stromal cell behavior. As such, the aim of this study was to investigate the modulations of human adipose-derived stem cell (hASCs) behavior within cell/particle and cell/composite systems as functions of particle size, concentration, and exposure time. The incorporation of nanoscale calcium phosphate resulted in improved mechanical properties and osteogenic behavior within the scaffold compared to the microscale calcium phosphate additives. Particle exposure results indicate that cytotoxicity on hASCs correlates inversely with particle size and increases with the increasing exposure time and particle concentration. Composites with increasing β-TCP content, whether microparticles or nanoparticles, were less toxic than colloidal micro- and nano-sized β-TCP particles directly supplied to hASCs. The difference in viability observed as a result of varying exposure route is likely related to the increased cell-particle interactions in the direct exposure compared to the particles becoming trapped within the scaffold/polymer matrix.

Structure and magnetic properties of Co and Ni nano-ferrites prepared by a two step direct microemulsions synthesis

NASA Astrophysics Data System (ADS)

Pulišová, P.; Kováč, J.; Voigt, A.; Raschman, P.

2013-09-01

Nano-particles of CoFe2O4, NiFe2O4 and Co0.5Ni0.5Fe2O4 were synthesized by a two step microemulsion precipitation where inverse micelles of water in hexanol were stabilized using cetyltrimethylammonium bromide. Powder X-ray diffraction analysis and Transmission electron microscopy measurements provided data to clarify the crystal structure and size of the produced nano-particles. Different measurements of magnetic properties at low temperatures of 2 K revealed that nano-particles of NiFe2O4 represent magnetically soft ferrite with a coercivity ∼40 kA/m, whereas nano-particles of CoFe2O4 and Co0.5Ni0.5Fe2O4 were magnetically harder with a coercivity of 815 and 947 kA/m, respectively. Additionally zero field cooling and field cooling measurements provided data for estimating the blocking temperature of the materials produced. For NiFe2O4 this temperature is lower, 23 K. The blocking temperature of CoFe2O4 of 238 K and Co0.5Ni0.5Fe2O4 of 268 K are higher in comparison with NiFe2O4.

Particle Size Influence on the Effective Permeability of Composite Materials

NASA Astrophysics Data System (ADS)

Xiang, Tai; Zhong, Ru-Neng; Yao, Bin; Qin, Shao-Jing; Zheng, Qin-Hong

2018-05-01

The energy method, which estimates the effective permeability of composite material is proposed. We approximate the effective static magnetic permeability by energy method and Maxwell-Garnett method for spherical particles dispersing system. Considering the effect of the interface layer between the medium and the particle, we study the nanoparticles embedded in a medium exactly. The interface layer property plays a significant factor for the effective permeability of the composite material in which nano-sized particles embedded. Supported by National Natural Science Foundation of Yunnan province under Grant No. 2014FB141 and National Natural Science Foundation under Grant No. 1121403 of China

Permanent magnet system to guide superparamagnetic particles

NASA Astrophysics Data System (ADS)

Baun, Olga; Blümler, Peter

2017-10-01

A new concept of using permanent magnet systems for guiding superparamagnetic nano-particles on arbitrary trajectories over a large volume is proposed. The basic idea is to use one magnet system which provides a strong, homogeneous, dipolar magnetic field to magnetize and orient the particles, and a second constantly graded, quadrupolar field, superimposed on the first, to generate a force on the oriented particles. In this configuration the motion of the particles is driven predominantly by the component of the gradient field which is parallel to the direction of the homogeneous field. As a result, particles are guided with constant force and in a single direction over the entire volume. The direction is simply adjusted by varying the angle between quadrupole and dipole. Since a single gradient is impossible due to Gauß' law, the other gradient component of the quadrupole determines the angular deviation of the force. However, the latter can be neglected if the homogeneous field is stronger than the local contribution of the quadrupole field. A possible realization of this idea is a coaxial arrangement of two Halbach cylinders. A dipole to evenly magnetize and orient the particles, and a quadrupole to generate the force. The local force was calculated analytically for this particular geometry and the directional limits were analyzed and discussed. A simple prototype was constructed to demonstrate the principle in two dimensions on several nano-particles of different size, which were moved along a rough square by manual adjustment of the force angle. The observed velocities of superparamagnetic particles in this prototype were always several orders of magnitude higher than the theoretically expected value. This discrepancy is attributed to the observed formation of long particle chains as a result of their polarization by the homogeneous field. The magnetic moment of such a chain is then the combination of that of its constituents, while its hydrodynamic radius

Synthesis of nano-sized ZnO particles by co-precipitation method with variation of heating time

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

Purwaningsih, S. Y., E-mail: sriyanisaputri@gmail.com; Pratapa, S.; Triwikantoro

Zinc oxide powders have been synthesized by a co-precipitation method at low temperature (85 °C), using zinc acetate dihydrate, ammonia, hydrochloric acid solutions as the reactants. A number of process parameters such as reaction temperature, solution basicity or pH and heating time are the main factors affecting the morphology and physical properties of the ZnO nanostructures. In this work the effect of heating time on the morphology and particles size were studied. The as-synthesized ZnO powders were characterized using transmission electron microscopy (TEM) and X-ray diffraction (XRD) techniques. The samples were also analyzed using Fourier transform infrared (FTIR). Rietveld refinementmore » of XRD data confirms that ZnO crystallizes in the hexagonal wurtzite structure with high degree of purity and the (101) plane predominant. The XRD results show that the average crystallite sizes were about 66, 27 and 12 nm for 3, 4 and 5 h of heating times, respectively. The XRD analysis indicated that a fraction of nano-sized ZnO powders were in the form of aggregates, which was also verified by TEM image. The TEM photograph demonstrated that the nano-sized ZnO particles were a pseudo-spherical shape.« less

Shape, size, and distribution of magnetic particles in Bjurbole chondrules

NASA Technical Reports Server (NTRS)

Nava, David F.

1994-01-01

Chondrules from the Bjurbole chondritic meteorite (L4) exhibit saturation remanence magnetization (SIRM) values which vary over three orders of magnitude. REM values (Natural Remanence Magnetization/SIRM) for Allende (C3V) and Chainpur (LL3) are less than 0.01 but in Bjurbole some chondrules were found to have REM values greater than 0.1 with several greater than 0.2. REM values greater than 0.1 are abnormal and cannot be acquired during weak field cooling. If exposure to a strong field (whatever the source) during the chondrules' history is responsible for the high REM values, was such history associated with a different processing which might have resulted in different shape, size, and distribution of metal particles compared to chondrules having REM values of less than 0.01? Furthermore, magnetic hysteresis results show a broad range of magnetic hardness and other intrinsic magnetic properties. These features must be related to (1) size and amount of metal; and (2) properties of, and amount of, tetrataenite in the chondrules (all chondrules thus far subjected to thermomagnetic analysis show the presence of tetrataenite). A scanning electron microscopy (SEM) study is underway to determine the relationship between the shape, size, and distribution of metal particles within individual chondrules and the magnetic properties of these chondrules. Results from the SEM study in conjunction with magnetic property data may also help to discern effects from possible lightning strikes in the nebula prior to incorporation of the chondrules into the parent body.

Particle Transport in Therapeutic Magnetic Fields

NASA Astrophysics Data System (ADS)

Puri, Ishwar K.; Ganguly, Ranjan

2014-01-01

Iron oxide magnetic nanoparticles, in ferrofluids or as magnetic microspheres, offer magnetic maneuverability, biochemical surface functionalization, and magnetic relaxation under the influence of an alternating field. The use of these properties for clinical applications requires an understanding of particles, forces, and scalar transport at various length scales. This review explains the behavior of magnetic nano- and microparticles during magnetic drug targeting and magnetic fluid hyperthermia, and the microfluidic transport of these particles in bioMEMS (biomedical microelectromechanical systems) devices for ex vivo therapeutic and diagnostic applications. Magnetic particle transport, the momentum interaction of these particles with a host fluid in a flow, and thermal transport in a particle-infused tissue are characterized through the governing electrodynamic, hydrodynamic, and scalar transport equations.

Effect of a nano-sized TiC particle addition on the flow-assisted corrosion resistance of SA 106B carbon steel

NASA Astrophysics Data System (ADS)

Park, Jin-Ju; Park, Eun-Kwang; Lee, Gyoung-Ja; Rhee, Chang-Kyu; Lee, Min-Ku

2017-09-01

Carbon steel with dispersed nano-sized TiC ceramic particles was fabricated by the ex-situ introduction of the particles into the melt, with the flow-assisted corrosion (FAC) resistance then investigated in the presence and absence of TiC nanoparticles using a once-through type of FAC loop test. From the potentiodynamic polarization curves, the current density at any given anodic potential was decreased and the open-circuit potential was increased by the addition of TiC nanoparticles. In addition, when the nano-sized TiC particles were added, the FAC rate was 1.38 times lower than that of carbon steel without TiC nanoparticles, indicating an improvement of the FAC resistance due to the homogeneous distribution of the TiC reinforcing nanoparticles.

Nano-sized and micro-sized polystyrene particles affect phagocyte function

PubMed Central

Prietl, B.; Meindl, C.; Roblegg, E.; Pieber, T. R.; Lanzer, G.; Fröhlich, E.

2015-01-01

Adverse effect of nanoparticles may include impairment of phagocyte function. To identify the effect of nanoparticle size on uptake, cytotoxicity, chemotaxis, cytokine secretion, phagocytosis, oxidative burst, nitric oxide production and myeloperoxidase release, leukocytes isolated from human peripheral blood, monocytes and macrophages were studied. Carboxyl polystyrene (CPS) particles in sizes between 20 and 1,000 nm served as model particles. Twenty nanometers CPS particles were taken up passively, while larger CPS particles entered cells actively and passively. Twenty nanometers CPS were cytotoxic to all phagocytes, ≥500 nm CPS particles only to macrophages. Twenty nanometers CPS particles stimulated IL-8 secretion in human monocytes and induced oxidative burst in monocytes. Five hundred nanometers and 1,000 nm CPS particles stimulated IL-6 and IL-8 secretion in monocytes and macrophages, chemotaxis towards a chemotactic stimulus of monocytes and phagocytosis of bacteria by macrophages and provoked an oxidative burst of granulocytes. At very high concentrations, CPS particles of 20 and 500 nm stimulated myeloperoxidase release of granulocytes and nitric oxide generation in macrophages. Cytotoxic effect could contribute to some of the observed effects. In the absence of cytotoxicity, 500 and 1,000 nm CPS particles appear to influence phagocyte function to a greater extent than particles in other sizes. PMID:24292270

Nano-sized and micro-sized polystyrene particles affect phagocyte function.

PubMed

Prietl, B; Meindl, C; Roblegg, E; Pieber, T R; Lanzer, G; Fröhlich, E

2014-02-01

Adverse effect of nanoparticles may include impairment of phagocyte function. To identify the effect of nanoparticle size on uptake, cytotoxicity, chemotaxis, cytokine secretion, phagocytosis, oxidative burst, nitric oxide production and myeloperoxidase release, leukocytes isolated from human peripheral blood, monocytes and macrophages were studied. Carboxyl polystyrene (CPS) particles in sizes between 20 and 1,000 nm served as model particles. Twenty nanometers CPS particles were taken up passively, while larger CPS particles entered cells actively and passively. Twenty nanometers CPS were cytotoxic to all phagocytes, ≥500 nm CPS particles only to macrophages. Twenty nanometers CPS particles stimulated IL-8 secretion in human monocytes and induced oxidative burst in monocytes. Five hundred nanometers and 1,000 nm CPS particles stimulated IL-6 and IL-8 secretion in monocytes and macrophages, chemotaxis towards a chemotactic stimulus of monocytes and phagocytosis of bacteria by macrophages and provoked an oxidative burst of granulocytes. At very high concentrations, CPS particles of 20 and 500 nm stimulated myeloperoxidase release of granulocytes and nitric oxide generation in macrophages. Cytotoxic effect could contribute to some of the observed effects. In the absence of cytotoxicity, 500 and 1,000 nm CPS particles appear to influence phagocyte function to a greater extent than particles in other sizes.

Characterisation of nano- and micron-sized airborne and collected subway particles, a multi-analytical approach.

PubMed

Midander, Klara; Elihn, Karine; Wallén, Anna; Belova, Lyuba; Karlsson, Anna-Karin Borg; Wallinder, Inger Odnevall

2012-06-15

Continuous daily measurements of airborne particles were conducted during specific periods at an underground platform within the subway system of the city center of Stockholm, Sweden. Main emphasis was placed on number concentration, particle size distribution, soot content (analyzed as elemental and black carbon) and surface area concentration. Conventional measurements of mass concentrations were conducted in parallel as well as analysis of particle morphology, bulk- and surface composition. In addition, the presence of volatile and semi volatile organic compounds within freshly collected particle fractions of PM(10) and PM(2.5) were investigated and grouped according to functional groups. Similar periodic measurements were conducted at street level for comparison. The investigation clearly demonstrates a large dominance in number concentration of airborne nano-sized particles compared to coarse particles in the subway. Out of a mean particle number concentration of 12000 particles/cm(3) (7500 to 20000 particles/cm(3)), only 190 particles/cm(3) were larger than 250 nm. Soot particles from diesel exhaust, and metal-containing particles, primarily iron, were observed in the subway aerosol. Unique measurements on freshly collected subway particle size fractions of PM(10) and PM(2.5) identified several volatile and semi-volatile organic compounds, the presence of carcinogenic aromatic compounds and traces of flame retardants. This interdisciplinary and multi-analytical investigation aims to provide an improved understanding of reported adverse health effects induced by subway aerosols. Copyright © 2012 Elsevier B.V. All rights reserved.

Optimization of perfluoro nano-scale emulsions: the importance of particle size for enhanced oxygen transfer in biomedical applications.

PubMed

Fraker, Christopher A; Mendez, Armando J; Inverardi, Luca; Ricordi, Camillo; Stabler, Cherie L

2012-10-01

Nano-scale emulsification has long been utilized by the food and cosmetics industry to maximize material delivery through increased surface area to volume ratios. More recently, these methods have been employed in the area of biomedical research to enhance and control the delivery of desired agents, as in perfluorocarbon emulsions for oxygen delivery. In this work, we evaluate critical factors for the optimization of PFC emulsions for use in cell-based applications. Cytotoxicity screening revealed minimal cytotoxicity of components, with the exception of one perfluorocarbon utilized for emulsion manufacture, perfluorooctylbromide (PFOB), and specific w% limitations of PEG-based surfactants utilized. We optimized the manufacture of stable nano-scale emulsions via evaluation of: component materials, emulsification time and pressure, and resulting particle size and temporal stability. The initial emulsion size was greatly dependent upon the emulsion surfactant tested, with pluronics providing the smallest size. Temporal stability of the nano-scale emulsions was directly related to the perfluorocarbon utilized, with perfluorotributylamine, FC-43, providing a highly stable emulsion, while perfluorodecalin, PFD, coalesced over time. The oxygen mass transfer, or diffusive permeability, of the resulting emulsions was also characterized. Our studies found particle size to be the critical factor affecting oxygen mass transfer, as increased micelle size resulted in reduced oxygen diffusion. Overall, this work demonstrates the importance of accurate characterization of emulsification parameters in order to generate stable, reproducible emulsions with the desired bio-delivery properties. Copyright © 2012 Elsevier B.V. All rights reserved.

Ultrasonic agitation-floating classification of nano-sized Ba-Mg ferrites particles formed by using self-propagating high temperature synthesis and fabrication of nickel-ferrites thin sheet by pulse-electroforming.

PubMed

Choi, Yong

2013-01-01

Nickel-nano-sized ferrites composites sheet for electromagnetic shielding was produced by pulse-electroforming in a modified nickel sulfamate solution. The ferrite particles were prepared by self-propagating high temperature synthesis (SHS) followed by mechanical milling, and classified with an ultrasonic agitation-floating unit to obtain about 100 nm in size. Average combustion temperature and combustion propagating rate during SHS reaction were 1190 K and 5.8 mm/sec at the oxygen pressure of 1.0 MPa, respectively. The nickel-ferrite composite sheet had preferred orientation which (100) pole clearly concentrated to normal direction, whereas, (110) and (111) poles tended to split to the longitudinal direction, respectively. Maximum magnetization, residual magnetization and coercive force of the nano-sized ferrites were 27.13 A x m2/kg, 6.4 A x m2/kg and 14.58 kA/m, respectively. Complex permeability of the composites decreased with an increase in frequency, and its real value (mu'r) had the maximum at about 0.3 GHz. The dielectric constants of the composites were epsilon'r = 6.7 and epsilon"r = 0.

Thermal conductivity enhancement and sedimentation reduction of magnetorheological fluids with nano-sized Cu and Al additives

NASA Astrophysics Data System (ADS)

Rahim, M. S. A.; Ismail, I.; Choi, S. B.; Azmi, W. H.; Aqida, S. N.

2017-11-01

This work presents enhanced material characteristics of smart magnetorheological (MR) fluids by utilizing nano-sized metal particles. Especially, enhancement of thermal conductivity and reduction of sedimentation rate of MR fluids those are crucial properties for applications of MR fluids are focussed. In order to achieve this goal, a series of MR fluid samples are prepared using carbonyl iron particles (CIP) and hydraulic oil, and adding nano-sized particles of copper (Cu), aluminium (Al), and fumed silica (SiO2). Subsequently, the thermal conductivity is measured by the thermal property analyser and the sedimentation of MR fluids is measured using glass tubes without any excitation for a long time. The measured thermal conductivity is then compared with theoretical models such as Maxwell model at various CIP concentrations. In addition, in order to show the effectiveness of MR fluids synthesized in this work, the thermal conductivity of MRF-132DG which is commercially available is measured and compared with those of the prepared samples. It is observed that the thermal conductivity of the samples is much better than MRF-132DG showing the 148% increment with 40 vol% of the magnetic particles. It is also observed that the sedimentation rate of the prepared MR fluid samples is less than that of MRF-132DG showing 9% reduction with 40 vol% of the magnetic particles. The mixture optimized sample with high conductivity and low sedimentation was also obtained. The magnetization of the sample recorded an enhancement of 70.5% when compared to MRF-132DG. Furthermore, the shear yield stress of the sample were also increased with and without the influence of magnetic field.

Micro/nano-particles and Cells: Manipulation, Transport, and Self-assembly

DTIC Science & Technology

2014-10-23

SECURITY CLASSIFICATION OF: Technologies that control nano- and micron- sized inert as well as biological materials are crucial to realizing engineered...that control nano- and micron- sized inert as well as biological materials are crucial to realizing engineered systems that can assemble, transport, and...nano-scale particles offer several advantages as building blocks of artificial materials . The relative ease of modifying their charge states

The behaviors of ferromagnetic nano-particles in and around blood vessels under applied magnetic fields

NASA Astrophysics Data System (ADS)

Nacev, A.; Beni, C.; Bruno, O.; Shapiro, B.

2011-03-01

In magnetic drug delivery, therapeutic magnetizable particles are typically injected into the blood stream and magnets are then used to concentrate them to disease locations. The behavior of such particles in-vivo is complex and is governed by blood convection, diffusion (in blood and in tissue), extravasation, and the applied magnetic fields. Using physical first-principles and a sophisticated vessel-membrane-tissue (VMT) numerical solver, we comprehensively analyze in detail the behavior of magnetic particles in blood vessels and surrounding tissue. For any blood vessel (of any size, depth, and blood velocity) and tissue properties, particle size and applied magnetic fields, we consider a Krogh tissue cylinder geometry and solve for the resulting spatial distribution of particles. We find that there are three prototypical behaviors (blood velocity dominated, magnetic force dominated, and boundary-layer formation) and that the type of behavior observed is uniquely determined by three non-dimensional numbers (the magnetic-Richardson number, mass Péclet number, and Renkin reduced diffusion coefficient). Plots and equations are provided to easily read out which behavior is found under which circumstances (Figs. 5-8). We compare our results to previously published in-vitro and in-vivo magnetic drug delivery experiments. Not only do we find excellent agreement between our predictions and prior experimental observations, but we are also able to qualitatively and quantitatively explain behavior that was previously not understood.

Thermoresponsive magnetic nano-biosensors for rapid measurements of inorganic arsenic and cadmium.

PubMed

Siddiki, Mohammad Shohel Rana; Shimoaoki, Shun; Ueda, Shunsaku; Maeda, Isamu

2012-10-18

Green fluorescent protein-tagged sensor proteins, ArsR-GFP and CadC-GFP, have been produced as biosensors for simple and low-cost quantification of As(III) or Cd(II). In this study, the sensor protein-promoter DNA complexes were reconstructed on the surfaces of magnetic particles of different sizes. After the surface modification all the particles could be attracted by magnets, and released different amounts of GFP-tagged protein, according to the metal concentrations within 5 min, which caused significant increases in fluorescence. A detection limit of 1 µg/L for As(III) and Cd(II) in purified water was obtained only with the nanoparticles exhibiting enough magnetization after heat treatment for 1 min. Therefore, thermoresponsive magnetic nano-biosensors offer great advantages of rapidity and sensitivity for the measurement of the toxic metals in drinking water.

Thermoresponsive Magnetic Nano-Biosensors for Rapid Measurements of Inorganic Arsenic and Cadmium

PubMed Central

Siddiki, Mohammad Shohel Rana; Shimoaoki, Shun; Ueda, Shunsaku; Maeda, Isamu

2012-01-01

Green fluorescent protein-tagged sensor proteins, ArsR-GFP and CadC-GFP, have been produced as biosensors for simple and low-cost quantification of As(III) or Cd(II). In this study, the sensor protein-promoter DNA complexes were reconstructed on the surfaces of magnetic particles of different sizes. After the surface modification all the particles could be attracted by magnets, and released different amounts of GFP-tagged protein, according to the metal concentrations within 5 min, which caused significant increases in fluorescence. A detection limit of 1 μg/L for As(III) and Cd(II) in purified water was obtained only with the nanoparticles exhibiting enough magnetization after heat treatment for 1 min. Therefore, thermoresponsive magnetic nano-biosensors offer great advantages of rapidity and sensitivity for the measurement of the toxic metals in drinking water. PMID:23202034

Dark field imaging system for size characterization of magnetic micromarkers

NASA Astrophysics Data System (ADS)

Malec, A.; Haiden, C.; Kokkinis, G.; Keplinger, F.; Giouroudi, I.

2017-05-01

In this paper we demonstrate a dark field video imaging system for the detection and size characterization of individual magnetic micromarkers suspended in liquid and the detection of pathogens utilizing magnetically labelled E.coli. The system follows dynamic processes and interactions of moving micro/nano objects close to or below the optical resolution limit, and is especially suitable for small sample volumes ( 10 μl). The developed detection method can be used to obtain clinical information about liquid contents when an additional biological protocol is provided, i.e., binding of microorganisms (e.g. E.coli) to specific magnetic markers. Some of the major advantages of our method are the increased sizing precision in the micro- and nano-range as well as the setup's simplicity making it a perfect candidate for miniaturized devices. Measurements can thus be carried out in a quick, inexpensive, and compact manner. A minor limitation is that the concentration range of micromarkers in a liquid sample needs to be adjusted in such a manner that the number of individual particles in the microscope's field of view is sufficient.

Magnetic properties in an ash flow tuff with continuous grain size variation: a natural reference for magnetic particle granulometry

USGS Publications Warehouse

Till, J.L.; Jackson, M.J.; Rosenbaum, J.G.; Solheid, P.

2011-01-01

The Tiva Canyon Tuff contains dispersed nanoscale Fe-Ti-oxide grains with a narrow magnetic grain size distribution, making it an ideal material in which to identify and study grain-size-sensitive magnetic behavior in rocks. A detailed magnetic characterization was performed on samples from the basal 5 m of the tuff. The magnetic materials in this basal section consist primarily of (low-impurity) magnetite in the form of elongated submicron grains exsolved from volcanic glass. Magnetic properties studied include bulk magnetic susceptibility, frequency-dependent and temperature-dependent magnetic susceptibility, anhysteretic remanence acquisition, and hysteresis properties. The combined data constitute a distinct magnetic signature at each stratigraphic level in the section corresponding to different grain size distributions. The inferred magnetic domain state changes progressively upward from superparamagnetic grains near the base to particles with pseudo-single-domain or metastable single-domain characteristics near the top of the sampled section. Direct observations of magnetic grain size confirm that distinct transitions in room temperature magnetic susceptibility and remanence probably denote the limits of stable single-domain behavior in the section. These results provide a unique example of grain-size-dependent magnetic properties in noninteracting particle assemblages over three decades of grain size, including close approximations of ideal Stoner-Wohlfarth assemblages, and may be considered a useful reference for future rock magnetic studies involving grain-size-sensitive properties.

Impact of agglomeration state of nano- and submicron sized gold particles on pulmonary inflammation

PubMed Central

2010-01-01

Background Nanoparticle (NP) toxicity testing comes with many challenges. Characterization of the test substance is of crucial importance and in the case of NPs, agglomeration/aggregation state in physiological media needs to be considered. In this study, we have addressed the effect of agglomerated versus single particle suspensions of nano- and submicron sized gold on the inflammatory response in the lung. Rats were exposed to a single dose of 1.6 mg/kg body weight (bw) of spherical gold particles with geometric diameters of 50 nm or 250 nm diluted either by ultrapure water or by adding phosphate buffered saline (PBS). A single dose of 1.6 mg/kg bw DQ12 quartz was used as a positive control for pulmonary inflammation. Extensive characterization of the particle suspensions has been performed by determining the zetapotential, pH, gold concentration and particle size distribution. Primary particle size and particle purity has been verified using transmission electron microscopy (TEM) techniques. Pulmonary inflammation (total cell number, differential cell count and pro-inflammatory cytokines), cell damage (total protein and albumin) and cytotoxicity (alkaline phosphatase and lactate dehydrogenase) were determined in bronchoalveolar lavage fluid (BALF) and acute systemic effects in blood (total cell number, differential cell counts, fibrinogen and C-reactive protein) 3 and 24 hours post exposure. Uptake of gold particles in alveolar macrophages has been determined by TEM. Results Particles diluted in ultrapure water are well dispersed, while agglomerates are formed when diluting in PBS. The particle size of the 50 nm particles was confirmed, while the 250 nm particles appear to be 200 nm using tracking analysis and 210 nm using TEM. No major differences in pulmonary and systemic toxicity markers were observed after instillation of agglomerated versus single gold particles of different sizes. Both agglomerated as well as single nanoparticles were taken up by

Effects of parallel magnetic field on electrocodeposition behavior of Fe/nano-Si particles composite electroplating

NASA Astrophysics Data System (ADS)

Zhou, Pengwei; Zhong, Yunbo; Wang, Huai; Long, Qiong; Li, Fu; Sun, Zongqian; Dong, Licheng; Fan, Lijun

2013-10-01

The influence of an external parallel strong parallel magnetic field (respect to current) on the electrocodeposition of nano-silicon particles into an iron matrix has been studied in this paper. Test results show that magnetic field has a great influence on the distribution of silicon, as well as the surface morphology and the thickness of the composite coatings. When no magnetic field was applied, a high current density was needed to get high concentration of silicon particles, while that could be easily obtained at a low current density with a 2 T parallel magnetic field. However, Owing to the unevenness of the current density J-distribution on the surface of the electrode in 8 T, the thicker and rougher composite deposits appear in the edge region (L or R region), and the thinner and smoother ones appear in the middle region (M). Meanwhile, the distribution curve of silicon content looks like a “pan” along the center line of coatings. A possible mechanism combining to the numerical simulation results was suggested out to illustrate the obtained experiment results.

On the possibility of magnetic nano-markers use for hydraulic fracturing in shale gas mining

NASA Astrophysics Data System (ADS)

Zawadzki, Jaroslaw; Bogacki, Jan

2016-04-01

Recently shale gas production became essential for the global economy, thanks to fast advances in shale fracturing technology. Shale gas extraction can be achieved by drilling techniques coupled with hydraulic fracturing. Further increasing of shale gas production is possible by improving the efficiency of hydraulic fracturing and assessing the spatial distribution of fractures in shale deposits. The latter can be achieved by adding magnetic markers to fracturing fluid or directly to proppant, which keeps the fracture pathways open. After that, the range of hydraulic fracturing can be assessed by measurement of vertical and horizontal component of earth's magnetic field before and after fracturing. The difference in these components caused by the presence of magnetic marker particles may allow to delineate spatial distribution of fractures. Due to the fact, that subterranean geological formations may contain minerals with significant magnetic properties, it is important to provide to the markers excellent magnetic properties which should be also, independent of harsh chemical and geological conditions. On the other hand it is of great significance to produce magnetic markers at an affordable price because of the large quantities of fracturing fluids or proppants used during shale fracturing. Examining the properties of nano-materials, it was found, that they possess clearly superior magnetic properties, as compared to the same structure but having a larger particle size. It should be then possible, to use lower amount of magnetic marker, to obtain the same effect. Although a research on properties of new magnetic nano-materials is very intensive, cheap magnetic nano-materials are not yet produced on a scale appropriate for shale gas mining. In this work we overview, in detail, geological, technological and economic aspects of using magnetic nano-markers in shale gas mining. Acknowledgment This work was supported by the NCBiR under Grant "Electromagnetic method to

Urban runoff treatment using nano-sized iron oxide coated sand with and without magnetic field applying

PubMed Central

2013-01-01

Increase of impervious surfaces in urban area followed with increases in runoff volume and peak flow, leads to increase in urban storm water pollution. The polluted runoff has many adverse impacts on human life and environment. For that reason, the aim of this study was to investigate the efficiency of nano iron oxide coated sand with and without magnetic field in treatment of urban runoff. In present work, synthetic urban runoff was treated in continuous separate columns system which was filled with nano iron oxide coated sand with and without magnetic field. Several experimental parameters such as heavy metals, turbidity, pH, nitrate and phosphate were controlled for investigate of system efficiency. The prepared column materials were characterized with Scanning Electron Microscopy (SEM) and Energy Dispersive X-ray analysis (EDXA) instruments. SEM and EDXA analyses proved that the sand has been coated with nano iron oxide (Fe3O4) successfully. The results of SEM and EDXA instruments well demonstrate the formation of nano iron oxide (Fe3O4) on sand particle. Removal efficiency without magnetic field for turbidity; Pb, Zn, Cd and PO4 were observed to be 90.8%, 73.3%, 75.8%, 85.6% and 67.5%, respectively. When magnetic field was applied, the removal efficiency for turbidity, Pb, Zn, Cd and PO4 was increased to 95.7%, 89.5%, 79.9%, 91.5% and 75.6% respectively. In addition, it was observed that coated sand and magnetic field was not able to remove NO3 ions. Statistical analyses of data indicated that there was a significant difference between removals of pollutants in two tested columns. Results of this study well demonstrate the efficiency of nanosized iron oxide-coated sand in treatment of urban runoff quality; upon 75% of pollutants could be removed. In addition, in the case of magnetic field system efficiency can be improved significantly. PMID:24360061

Elucidation of the mechanisms of action of Bacteriophage K/nano-emulsion formulations against S. aureus via measurement of particle size and zeta potential.

PubMed

Esteban, Patricia Perez; Jenkins, A Toby A; Arnot, Tom C

2016-03-01

In earlier work we have demonstrated the effect that nano-emulsions have on bacterial growth, and most importantly the enhanced bacteriophage infectivity against Staphylococcus aureus in planktonic culture when phage are carried in nano-emulsions. However, the mechanisms of enhancement of the bacteriophage killing effect are not specifically understood. This work focuses on the investigation of the possible interactions between emulsion droplets and bacterial cells, between emulsion droplets and bacteriophages, and finally interactions between all three components: nano-emulsion droplets, bacteria, and bacteriophages. The first approach consists of simple calculations to determine the spatial distribution of the components, based on measurements of particle size. It was found that nano-emulsion droplets are much more numerous than bacteria or bacteriophage, and due to their size and surface area they must be covering the surface of both cells and bacteriophage particles. Stabilisation of bacteriophages due to electrostatic forces and interaction with nano-emulsion droplets is suspected, since bacteriophages may be protected against inactivation due to 'charge shielding'. Zeta potential was measured for the individual components in the system, and for all of them combined. It was concluded that the presence of nano-emulsions could be reducing electrostatic repulsion between bacterial cells and bacteriophage, both of which are very negatively 'charged'. Moreover, nano-emulsions lead to more favourable interaction between bacteriophages and bacteria, enhancing the anti-microbial or killing effect. These findings are relevant since the physicochemical properties of nano-emulsions (i.e. particle size distribution and zeta potential) are key in determining the efficacy of the formulation against infection in the context of responsive burn wound dressings-which is the main target for this work. Copyright © 2015 The Authors. Published by Elsevier B.V. All rights reserved.

Nano-sized particles, processes of making, compositions and uses thereof

DOEpatents

O'Brien, Stephen [New York, NY; Yin, Ming [Los Alamos, NM

2012-05-22

The present invention describes methods for preparing high quality nanoparticles, i.e., metal oxide based nanoparticles of uniform size and monodispersity. The nanoparticles advantageously comprise organic alkyl chain capping groups and are stable in air and in nonpolar solvents. The methods of the invention provide a simple and reproducible procedure for forming transition metal oxide nanocrystals, with yields over 80%. The highly crystalline and monodisperse nanocrystals are obtained directly without further size selection; particle size can be easily and fractionally increased by the methods. The resulting nanoparticles can exhibit magnetic and/or optical properties. These properties result from the methods used to prepare them. Also advantageously, the nanoparticles of this invention are well suited for use in a variety of industrial applications, including cosmetic and pharmaceutical formulations and compositions.

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.

Numerical simulation of magnetic nano drug targeting in patient-specific lower respiratory tract

NASA Astrophysics Data System (ADS)

Russo, Flavia; Boghi, Andrea; Gori, Fabio

2018-04-01

Magnetic nano drug targeting, with an external magnetic field, can potentially improve the drug absorption in specific locations of the body. However, the effectiveness of the procedure can be reduced due to the limitations of the magnetic field intensity. This work investigates this technique with the Computational Fluid Dynamics (CFD) approach. A single rectangular coil generates the external magnetic field. A patient-specific geometry of the Trachea, with its primary and secondary bronchi, is reconstructed from Digital Imaging and Communications in Medicine (DICOM) formatted images, throughout the Vascular Modelling Tool Kit (VMTK) software. A solver, coupling the Lagrangian dynamics of the magnetic nanoparticles with the Eulerian dynamics of the air, is used to perform the simulations. The resistive pressure, the pulsatile inlet velocity and the rectangular coil magnetic field are the boundary conditions. The dynamics of the injected particles is investigated without and with the magnetic probe. The flow field promotes particles adhesion to the tracheal wall. The particles volumetric flow rate in both cases has been calculated. The magnetic probe is shown to increase the particles flow in the target region, but at a limited extent. This behavior has been attributed to the small particle size and the probe configuration.

Compression Properties and Electrical Conductivity of In-Situ 20 vol.% Nano-Sized TiCx/Cu Composites with Different Particle Size and Morphology

PubMed Central

Zhang, Dongdong; Bai, Fang; Sun, Liping; Wang, Yong; Wang, Jinguo

2017-01-01

The compression properties and electrical conductivity of in-situ 20 vol.% nano-sized TiCx/Cu composites fabricated via combustion synthesis and hot press in Cu-Ti-CNTs system at various particles size and morphology were investigated. Cubic-TiCx/Cu composite had higher ultimate compression strength (σUCS), yield strength (σ0.2), and electric conductivity, compared with those of spherical-TiCx/Cu composite. The σUCS, σ0.2, and electrical conductivity of cubic-TiCx/Cu composite increased by 4.37%, 20.7%, and 17.8% compared with those of spherical-TiCx/Cu composite (526 MPa, 183 MPa, and 55.6% International Annealed Copper Standard, IACS). Spherical-TiCx/Cu composite with average particle size of ~94 nm exhibited higher ultimate compression strength, yield strength, and electrical conductivity compared with those of spherical-TiCx/Cu composite with 46 nm in size. The σUCS, σ0.2, and electrical conductivity of spherical-TiCx/Cu composite with average size of ~94 nm in size increased by 17.8%, 33.9%, and 62.5% compared with those of spherical-TiCx/Cu composite (417 MPa, 121 MPa, and 40.3% IACS) with particle size of 49 nm, respectively. Cubic-shaped TiCx particles with sharp corners and edges led to stress/strain localization, which enhanced the compression strength of the composites. The agglomeration of spherical-TiCx particles with small size led to the compression strength reduction of the composites. PMID:28772859

Airflow structures and nano-particle deposition in a human upper airway model

NASA Astrophysics Data System (ADS)

Zhang, Z.; Kleinstreuer, C.

2004-07-01

Considering a human upper airway model, or equivalently complex internal flow conduits, the transport and deposition of nano-particles in the 1-150 nm diameter range are simulated and analyzed for cyclic and steady flow conditions. Specifically, using a commercial finite-volume software with user-supplied programs as a solver, the Euler-Euler approach for the fluid-particle dynamics is employed with a low-Reynolds-number k- ω model for laminar-to-turbulent airflow and the mass transfer equation for dispersion of nano-particles or vapors. Presently, the upper respiratory system consists of two connected segments of a simplified human cast replica, i.e., the oral airways from the mouth to the trachea (Generation G0) and an upper tracheobronchial tree model of G0-G3. Experimentally validated computational fluid-particle dynamics results show the following: (i) transient effects in the oral airways appear most prominently during the decelerating phase of the inspiratory cycle; (ii) selecting matching flow rates, total deposition fractions of nano-size particles for cyclic inspiratory flow are not significantly different from those for steady flow; (iii) turbulent fluctuations which occur after the throat can persist downstream to at least Generation G3 at medium and high inspiratory flow rates (i.e., Qin⩾30 l/min) due to the enhancement of flow instabilities just upstream of the flow dividers; however, the effects of turbulent fluctuations on nano-particle deposition are quite minor in the human upper airways; (iv) deposition of nano-particles occurs to a relatively greater extent around the carinal ridges when compared to the straight tubular segments in the bronchial airways; (v) deposition distributions of nano-particles vary with airway segment, particle size, and inhalation flow rate, where the local deposition is more uniformly distributed for large-size particles (say, dp=100 nm) than for small-size particles (say, dp=1 nm); (vi) dilute 1 nm particle

Huge Inverse Magnetization Generated by Faraday Induction in Nano-Sized Au@Ni Core@Shell Nanoparticles.

PubMed

Kuo, Chen-Chen; Li, Chi-Yen; Lee, Chi-Hung; Li, Hsiao-Chi; Li, Wen-Hsien

2015-08-25

We report on the design and observation of huge inverse magnetizations pointing in the direction opposite to the applied magnetic field, induced in nano-sized amorphous Ni shells deposited on crystalline Au nanoparticles by turning the applied magnetic field off. The magnitude of the induced inverse magnetization is very sensitive to the field reduction rate as well as to the thermal and field processes before turning the magnetic field off, and can be as high as 54% of the magnetization prior to cutting off the applied magnetic field. Memory effect of the induced inverse magnetization is clearly revealed in the relaxation measurements. The relaxation of the inverse magnetization can be described by an exponential decay profile, with a critical exponent that can be effectively tuned by the wait time right after reaching the designated temperature and before the applied magnetic field is turned off. The key to these effects is to have the induced eddy current running beneath the amorphous Ni shells through Faraday induction.

Dynamics of magnetic particles in cylindrical Halbach array: implications for magnetic cell separation and drug targeting.

PubMed

Babinec, Peter; Krafcík, Andrej; Babincová, Melánia; Rosenecker, Joseph

2010-08-01

Magnetic nanoparticles for therapy and diagnosis are at the leading edge of the rapidly developing field of bionanotechnology. In this study, we have theoretically studied motion of magnetic nano- as well as micro-particles in the field of cylindrical Halbach array of permanent magnets. Magnetic flux density was modeled as magnetostatic problem by finite element method and particle motion was described using system of ordinary differential equations--Newton law. Computations were done for nanoparticles Nanomag-D with radius 65 nm, which are often used in magnetic drug targeting, as well as microparticles DynaBeads-M280 with radius 1.4 microm, which can be used for magnetic separation. Analyzing snapshots of trajectories of hundred magnetite particles of each size in the water as well as in the air, we have found that optimally designed magnetic circuits of permanent magnets in quadrupolar Halbach array have substantially shorter capture time than simple blocks of permanent magnets commonly used in experiments, therefore, such a Halbach array may be useful as a potential source of magnetic field for magnetic separation and targeting of magnetic nanoparticles as well as microparticles for delivery of drugs, genes, and cells in various biomedical applications.

Copper Modified Magnetic Bimetallic Nano-catalysts Ligand Regulated Catalytic Activity

EPA Science Inventory

Postsynthetic modification of magnetic nano ferrites (Fe3O4) has been accomplished by anchoring glutathione and dopamine on the surface. The Cu nano particles immobilized over these surfaces were investigated for the coupling and cyclo addition reactions. The Fe3O4-DOPA-Cu (na...

The Isolation of DNA by Polycharged Magnetic Particles: An Analysis of the Interaction by Zeta Potential and Particle Size

PubMed Central

Haddad, Yazan; Xhaxhiu, Kledi; Kopel, Pavel; Hynek, David; Zitka, Ondrej; Adam, Vojtech

2016-01-01

Magnetic isolation of biological targets is in major demand in the biotechnology industry today. This study considers the interaction of four surface-modified magnetic micro- and nanoparticles with selected DNA fragments. Different surface modifications of nanomaghemite precursors were investigated: MAN37 (silica-coated), MAN127 (polyvinylpyrrolidone-coated), MAN158 (phosphate-coated), and MAN164 (tripolyphosphate-coated). All particles were positive polycharged agglomerated monodispersed systems. Mean particle sizes were 0.48, 2.97, 2.93, and 3.67 μm for MAN37, MAN127, MAN164, and MAN158, respectively. DNA fragments exhibited negative zeta potential of −0.22 mV under binding conditions (high ionic strength, low pH, and dehydration). A decrease in zeta potential of particles upon exposure to DNA was observed with exception of MAN158 particles. The measured particle size of MAN164 particles increased by nearly twofold upon exposure to DNA. Quantitative PCR isolation of DNA with a high retrieval rate was observed by magnetic particles MAN127 and MAN164. Interaction between polycharged magnetic particles and DNA is mediated by various binding mechanisms such as hydrophobic and electrostatic interactions. Future development of DNA isolation technology requires an understanding of the physical and biochemical conditions of this process. PMID:27104527

The Isolation of DNA by Polycharged Magnetic Particles: An Analysis of the Interaction by Zeta Potential and Particle Size.

PubMed

Haddad, Yazan; Xhaxhiu, Kledi; Kopel, Pavel; Hynek, David; Zitka, Ondrej; Adam, Vojtech

2016-04-20

Magnetic isolation of biological targets is in major demand in the biotechnology industry today. This study considers the interaction of four surface-modified magnetic micro- and nanoparticles with selected DNA fragments. Different surface modifications of nanomaghemite precursors were investigated: MAN37 (silica-coated), MAN127 (polyvinylpyrrolidone-coated), MAN158 (phosphate-coated), and MAN164 (tripolyphosphate-coated). All particles were positive polycharged agglomerated monodispersed systems. Mean particle sizes were 0.48, 2.97, 2.93, and 3.67 μm for MAN37, MAN127, MAN164, and MAN158, respectively. DNA fragments exhibited negative zeta potential of -0.22 mV under binding conditions (high ionic strength, low pH, and dehydration). A decrease in zeta potential of particles upon exposure to DNA was observed with exception of MAN158 particles. The measured particle size of MAN164 particles increased by nearly twofold upon exposure to DNA. Quantitative PCR isolation of DNA with a high retrieval rate was observed by magnetic particles MAN127 and MAN164. Interaction between polycharged magnetic particles and DNA is mediated by various binding mechanisms such as hydrophobic and electrostatic interactions. Future development of DNA isolation technology requires an understanding of the physical and biochemical conditions of this process.

Engineered nano particles: Nature, behavior, and effect on the environment.

PubMed

Goswami, Linee; Kim, Ki-Hyun; Deep, Akash; Das, Pallabi; Bhattacharya, Satya Sundar; Kumar, Sandeep; Adelodun, Adedeji A

2017-07-01

Increased application of engineered nano particles (ENPs) in production of various appliances and consumer items is increasing their presence in the natural environment. Although a wide variety of nano particles (NPs) are ubiquitously dispersed in ecosystems, risk assessment guidelines to describe their ageing, direct exposure, and long-term accumulation characteristics are poorly developed. In this review, we describe what is known about the life cycle of ENPs and their impact on natural systems and examine if there is a cohesive relationship between their transformation processes and bio-accessibility in various food chains. Different environmental stressors influence the fate of these particles in the environment. Composition of solid media, pore size, solution chemistry, mineral composition, presence of natural organic matter, and fluid velocity are some environmental stressors that influence the transformation, transport, and mobility of nano particles. Transformed nano particles can reduce cell viability, growth and morphology, enhance oxidative stress, and damage DNA in living organisms. Copyright © 2017 Elsevier Ltd. All rights reserved.

Performance evaluation of bimodal thermite composites : nano- vs miron-scale particles

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

Moore, K. M.; Pantoya, M.; Son, S. F.

2004-01-01

In recent years many studies of metastable interstitial composites (MIC) have shown vast combustion improvements over traditional thermite materials. The main difference between these two materials is the size of the fuel particles in the mixture. Decreasing the fuel size from the micron to nanometer range significantly increases the combustion wave speed and ignition sensitivity. Little is known, however, about the critical level of nano-sized fuel particles needed to enhance the performance of the traditional thermite. Ignition sensitivity experiments were performed using Al/MoO{sub 3} pellets at a theoretical maximum density of 50% (2 g/cm{sup 3}). The Al fuel particles weremore » prepared as bi-modal size distributions with micron (i.e., 4 and 20 {micro}m diameter) and nano-scale Al particles. The micron-scale Al was replaced in 10% increments by 80 nm Al particles until the fuel was 100% 80 nm Al. These bi-modal distributions allow the unique characteristics of nano-scale materials to be better understood. The pellets were ignited using a 50-W CO{sub 2} laser. High speed imaging diagnostics were used to measure ignition delay times, and micro-thermocouples were used to measure ignition temperatures. Combustion wave speeds were also examined.« less

The Entry of Nano-dust Particles into the Terrestrial Magnetosphere

NASA Astrophysics Data System (ADS)

Horanyi, M.; Juhasz, A.

2016-12-01

Nano-dust particles have been suggested to be responsible for spurious antenna signals on several spacecraft near 1 AU. Most of these tiny motes are generated in the solar vicinity where the collision-rate between larger inward migrating dust particles increases generating copious amounts of smaller dust grains. The vast majority of the dust grains is predicted to be lost to the Sun, but a fraction of them can be expelled by radiation pressure, and the solar wind plasma flow. Particles in the nano-meter size range can be incorporated in the solar wind, and arrive near 1 AU with characteristic speeds of approximately 400 km/s. Larger, but still submicron sized particles, that are expelled by radiation pressure, represent the so-called beta-meteoroid population. Both of these populations of dust particles can be detected by dedicated dust instruments near 1 AU. A fraction of these particles can also penetrate the terrestrial magnetosphere and possibly bombard spacecraft orbiting the Earth. This talk will explore the dynamics of nano-grains and beta-meteoroids entering the magnetosphere, and predict their spatial, mass and speed distributions as function of solar wind conditions.

Dynamics of magnetic single domain particles embedded in a viscous liquid

NASA Astrophysics Data System (ADS)

Usadel, K. D.; Usadel, C.

2015-12-01

Kinetic equations for magnetic nano particles dispersed in a viscous liquid are developed and analyzed numerically. Depending on the amplitude of an applied oscillatory magnetic field, the particles orient their time averaged anisotropy axis perpendicular to the applied field for low magnetic field amplitudes and nearly parallel to the direction of the field for high amplitudes. The transition between these regions takes place in a narrow field interval. In the low field region, the magnetic moment is locked to some crystal axis and the energy absorption in an oscillatory driving field is dominated by viscous losses associated with particle rotation in the liquid. In the opposite limit, the magnetic moment rotates within the particle while its easy axis being nearly parallel to the external field direction oscillates. The kinetic equations are generalized to include thermal fluctuations. This leads to a significant increase of the power absorption in the low and intermediate field regions with a pronounced absorption peak as function of particle size. In the high field region, on the other hand, the inclusion of thermal fluctuations reduces the power absorption. The illustrative numerical calculations presented are performed for magnetic parameters typical for iron oxide.

Thermal annealing behavior of nano-size metal-oxide particles synthesized by ion implantation in Fe-Cr alloy

NASA Astrophysics Data System (ADS)

Zheng, C.; Gentils, A.; Ribis, J.; Borodin, V. A.; Descoins, M.; Mangelinck, D.; Dalle, F.; Arnal, B.; Delauche, L.

2017-05-01

Oxide dispersion strengthened (ODS) steels are promising structural materials for the next generation nuclear reactors, as well as fusion facilities. The detailed understanding of the mechanisms involved in the precipitation of nano-oxides during ODS steel production would strongly contribute to the improvement of the mechanical properties and the optimization of manufacturing of ODS steels, with a potentially strong economic impact for their industrialization. A useful tool for the experimental study of nano-oxide precipitation is ion implantation, a technique that is widely used to synthesize precipitate nanostructures in well-controlled conditions. Earlier, we have demonstrated the feasibility of synthesizing aluminum-oxide particles in the high purity Fe-10Cr alloy by consecutive implantation with Al and O ions at room temperature. This paper describes the effects of high-temperature annealing after the ion implantation stage on the development of the aluminum based oxide nanoparticle system. Using transmission electron microscopy and atom probe tomography experiments, we demonstrate that post-implantation heat treatment induces the growth of the nano-sized oxides in the implanted region and nucleation of new oxide precipitates behind the implantation zone as a result of the diffusion driven broadening of implant profiles. A tentative scenario for the development of metal-oxide nano-particles at both ion implantation and heat treatment stages is suggested based on the experimental observations.

Synthesis and Characterization of Cholesterol Nano Particles by Using w/o Microemulsion Technique

NASA Astrophysics Data System (ADS)

Vyas, Poorvesh M.; Vasant, Sonal R.; Hajiyani, Rakesh R.; Joshi, Mihir J.

2010-10-01

Cholesterol is one of the most abundant and well known steroids in the animal kingdom. Cholesterol rich micro-emulsions and nano-emulsions are useful for the treatment of breast cancer and gynecologic cancers. The nano particles of cholesterol and other pharmaceutically important materials have been reported. In the present investigation, the nano particles of cholesterol were synthesized by direct precipitation technique using triton X-100/water/n-butanol micro-emulsion. The average particle size of cholesterol nano particles was estimated by applying Scherrer's formula to the powder X-ray diffraction pattern, which was found to be 22 nm. The nanoparticles of cholesterol were observed by using TEM and the particle size was found within the range from 15 nm-31 nm. The distribution of particle size was studied through DLS. The nanoparticles of cholesterol were characterized by using FT-IR spectroscopy and the force constant was also calculated for O-H, C-H and C-O bonds. The thermal response of nanoparticles of cholesterol was studied by TGA, which showed that the nanoparticles were stable up to 200 °C and then decomposed. Kinetic and thermodynamic parameters of decomposition process were also calculated by applying Coats and Redfern formula to thermo-gram.

A comparison of two nano-sized particle air filtration tests in the diameter range of 10 to 400 nanometers

NASA Astrophysics Data System (ADS)

Japuntich, Daniel A.; Franklin, Luke M.; Pui, David Y.; Kuehn, Thomas H.; Kim, Seong Chan; Viner, Andrew S.

2007-01-01

Two different air filter test methodologies are discussed and compared for challenges in the nano-sized particle range of 10-400 nm. Included in the discussion are test procedure development, factors affecting variability and comparisons between results from the tests. One test system which gives a discrete penetration for a given particle size is the TSI 8160 Automated Filter tester (updated and commercially available now as the TSI 3160) manufactured by the TSI, Inc., Shoreview, MN. Another filter test system was developed utilizing a Scanning Mobility Particle Sizer (SMPS) to sample the particle size distributions downstream and upstream of an air filter to obtain a continuous percent filter penetration versus particle size curve. Filtration test results are shown for fiberglass filter paper of intermediate filtration efficiency. Test variables affecting the results of the TSI 8160 for NaCl and dioctyl phthalate (DOP) particles are discussed, including condensation particle counter stability and the sizing of the selected particle challenges. Filter testing using a TSI 3936 SMPS sampling upstream and downstream of a filter is also shown with a discussion of test variables and the need for proper SMPS volume purging and filter penetration correction procedure. For both tests, the penetration versus particle size curves for the filter media studied follow the theoretical Brownian capture model of decreasing penetration with decreasing particle diameter down to 10 nm with no deviation. From these findings, the authors can say with reasonable confidence that there is no evidence of particle thermal rebound in the size range.

Magnetic agglomeration method for size control in the synthesis of magnetic nanoparticles

DOEpatents

Huber, Dale L [Albuquerque, NM

2011-07-05

A method for controlling the size of chemically synthesized magnetic nanoparticles that employs magnetic interaction between particles to control particle size and does not rely on conventional kinetic control of the reaction to control particle size. The particles are caused to reversibly agglomerate and precipitate from solution; the size at which this occurs can be well controlled to provide a very narrow particle size distribution. The size of particles is controllable by the size of the surfactant employed in the process; controlling the size of the surfactant allows magnetic control of the agglomeration and precipitation processes. Agglomeration is used to effectively stop particle growth to provide a very narrow range of particle sizes.

A Facile Method for Separating and Enriching Nano and Submicron Particles from Titanium Dioxide Found in Food and Pharmaceutical Products.

PubMed

Faust, James J; Doudrick, Kyle; Yang, Yu; Capco, David G; Westerhoff, Paul

2016-01-01

Recent studies indicate the presence of nano-scale titanium dioxide (TiO2) as an additive in human foodstuffs, but a practical protocol to isolate and separate nano-fractions from soluble foodstuffs as a source of material remains elusive. As such, we developed a method for separating the nano and submicron fractions found in commercial-grade TiO2 (E171) and E171 extracted from soluble foodstuffs and pharmaceutical products (e.g., chewing gum, pain reliever, and allergy medicine). Primary particle analysis of commercial-grade E171 indicated that 54% of particles were nano-sized (i.e., < 100 nm). Isolation and primary particle analysis of five consumer goods intended to be ingested revealed differences in the percent of nano-sized particles from 32%‒58%. Separation and enrichment of nano- and submicron-sized particles from commercial-grade E171 and E171 isolated from foodstuffs and pharmaceuticals was accomplished using rate-zonal centrifugation. Commercial-grade E171 was separated into nano- and submicron-enriched fractions consisting of a nano:submicron fraction of approximately 0.45:1 and 3.2:1, respectively. E171 extracted from gum had nano:submicron fractions of 1.4:1 and 0.19:1 for nano- and submicron-enriched, respectively. We show a difference in particle adhesion to the cell surface, which was found to be dependent on particle size and epithelial orientation. Finally, we provide evidence that E171 particles are not immediately cytotoxic to the Caco-2 human intestinal epithelium model. These data suggest that this separation method is appropriate for studies interested in isolating the nano-sized particle fraction taken directly from consumer products, in order to study separately the effects of nano and submicron particles.

A Facile Method for Separating and Enriching Nano and Submicron Particles from Titanium Dioxide Found in Food and Pharmaceutical Products

PubMed Central

Yang, Yu; Capco, David G.; Westerhoff, Paul

2016-01-01

Recent studies indicate the presence of nano-scale titanium dioxide (TiO2) as an additive in human foodstuffs, but a practical protocol to isolate and separate nano-fractions from soluble foodstuffs as a source of material remains elusive. As such, we developed a method for separating the nano and submicron fractions found in commercial-grade TiO2 (E171) and E171 extracted from soluble foodstuffs and pharmaceutical products (e.g., chewing gum, pain reliever, and allergy medicine). Primary particle analysis of commercial-grade E171 indicated that 54% of particles were nano-sized (i.e., < 100 nm). Isolation and primary particle analysis of five consumer goods intended to be ingested revealed differences in the percent of nano-sized particles from 32%‒58%. Separation and enrichment of nano- and submicron-sized particles from commercial-grade E171 and E171 isolated from foodstuffs and pharmaceuticals was accomplished using rate-zonal centrifugation. Commercial-grade E171 was separated into nano- and submicron-enriched fractions consisting of a nano:submicron fraction of approximately 0.45:1 and 3.2:1, respectively. E171 extracted from gum had nano:submicron fractions of 1.4:1 and 0.19:1 for nano- and submicron-enriched, respectively. We show a difference in particle adhesion to the cell surface, which was found to be dependent on particle size and epithelial orientation. Finally, we provide evidence that E171 particles are not immediately cytotoxic to the Caco-2 human intestinal epithelium model. These data suggest that this separation method is appropriate for studies interested in isolating the nano-sized particle fraction taken directly from consumer products, in order to study separately the effects of nano and submicron particles. PMID:27798677

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

Lab-on-a-disc agglutination assay for protein detection by optomagnetic readout and optical imaging using nano- and micro-sized magnetic beads.

PubMed

Uddin, Rokon; Burger, Robert; Donolato, Marco; Fock, Jeppe; Creagh, Michael; Hansen, Mikkel Fougt; Boisen, Anja

2016-11-15

We present a biosensing platform for the detection of proteins based on agglutination of aptamer coated magnetic nano- or microbeads. The assay, from sample to answer, is integrated on an automated, low-cost microfluidic disc platform. This ensures fast and reliable results due to a minimum of manual steps involved. The detection of the target protein was achieved in two ways: (1) optomagnetic readout using magnetic nanobeads (MNBs); (2) optical imaging using magnetic microbeads (MMBs). The optomagnetic readout of agglutination is based on optical measurement of the dynamics of MNB aggregates whereas the imaging method is based on direct visualization and quantification of the average size of MMB aggregates. By enhancing magnetic particle agglutination via application of strong magnetic field pulses, we obtained identical limits of detection of 25pM with the same sample-to-answer time (15min 30s) using the two differently sized beads for the two detection methods. In both cases a sample volume of only 10µl is required. The demonstrated automation, low sample-to-answer time and portability of both detection instruments as well as integration of the assay on a low-cost disc are important steps for the implementation of these as portable tools in an out-of-lab setting. Copyright © 2016 Elsevier B.V. All rights reserved.

Synthesis of Calcite Nano Particles from Natural Limestone assisted with Ultrasonic Technique

NASA Astrophysics Data System (ADS)

Handayani, M.; Sulistiyono, E.; Firdiyono, F.; Fajariani, E. N.

2018-03-01

This article represents a precipitation method assisted with ultrasonic process to synthesize precipitated calcium carbonate nano particles from natural limestone. The synthesis of nanoparticles material of precipitated calcium carbonate from commercial calcium carbonate was done for comparison. The process was performed using ultrasonic waves at optimum condition, that is, at temperature of 80oC for 10 minutes with various amplitudes. Synthesized precipitated calcium carbonate nanoparticles were characterized using X-Ray Diffraction (XRD), Scanning Electron Microscope (SEM) and Particle Size Analyzer (PSA). The result of PSA measurements showed that precipitated calcium carbonate nano particles was obtained with the average size of 109 nm.

Radiopacifier Particle Size Impacts the Physical Properties of Tricalcium Silicate–based Cements

PubMed Central

Saghiri, Mohammad Ali; Gutmann, James L.; Orangi, Jafar; Asatourian, Armen; Sheibani, Nader

2016-01-01

Introduction The aim of this study was to evaluate the impact of radiopaque additive, bismuth oxide, particle size on the physical properties, and radiopacity of tricalcium silicate–based cements. Methods Six types of tricalcium silicate cement (CSC) including CSC without bismuth oxide, CSC + 10% (wt%) regular bismuth oxide (particle size 10 μm), CSC + 20% regular bismuth oxide (simulating white mineral trioxide aggregate [WMTA]) as a control, CSC + 10% nano bismuth oxide (particle size 50–80 nm), CSC + 20% nano-size bismuth oxide, and nano WMTA (a nano modification of WMTA comprising nanoparticles in the range of 40–100 nm) were prepared. Twenty-four samples from each group were divided into 4 groups and subjected to push-out, surface microhardness, radiopacity, and compressive strength tests. Data were analyzed by 1-way analysis of variance with the post hoc Tukey test. Results The push-out and compressive strength of CSC without bismuth oxide and CSC with 10% and 20% nano bismuth oxide were significantly higher than CSC with 10% or 20% regular bismuth oxide (P < .05). The surface micro-hardness of CSC without bismuth oxide and CSC with 10% regular bismuth oxide had the lowest values (P < .05). The lowest radiopacity values were seen in CSC without bismuth oxide and CSC with 10% nano bismuth oxide (P < .05). Nano WMTA samples showed the highest values for all tested properties (P < .05) except for radiopacity. Conclusions The addition of 20% nano bismuth oxide enhanced the physical properties of CSC without any significant changes in radiopacity. Regular particle-size bismuth oxide reduced the physical properties of CSC material for tested parameters. PMID:25492489

Spatial redistribution of nano-particles using electrokinetic micro-focuser

NASA Astrophysics Data System (ADS)

Garcia, Daniel E.; Silva, Aleidy; Ho, Chih-Ming

2007-09-01

Current microfabrication technologies rely on top-down, photolithographic techniques that are ultimately limited by the wavelength of light. While systems for nanofabrication do exist, they frequently suffer from high costs and slow processing times, creating a need for a new manufacturing paradigm. The combination of top-down and bottom-up fabrication approaches in device construction creates a new paradigm in micro- and nano-manufacturing. The pre-requisite for the realization of the manufacturing paradigm relies on the manipulation of molecules in a deterministic and controlled manner. The use of AC electrokinetic forces, such as dielectrophoresis (DEP) and AC electroosmosis, is a promising technology for manipulating nano-sized particle in a parallel fashion. A three-electrode micro-focusing system was designed to expoit this forces in order to control the spatial distribution of nano-particles in different frequency ranges. Thus far, we have demonstrated the ability to concentrate 40 nm and 300 nm diameter particles using a 50 μm diameter focusing system. AC electroosmotic motion of the nano-particles was observed while using low frequencies (in a range of 30 Hz - 1 KHz). By using different frequencies and changing the ground location, we have manipulated the nano-particles into circular band structures with different width, and focused the nanoparticles into circular spots with different diameters. Currently, we are in the progress of optimizing the operation parameters (e.g. frequency and AC voltages) by using the technique of particle image velocimetry (PIV). In the future, design of different electrode geometries and the numerical simulation of electric field distribution will be carried out to manipulate the nano-particles into a variety of geometries.

DEPOSITION DISTRIBUTION OF NANO AND ULTRAFINE PARTICLES IN HUMAN LUNGS DURING CONTROLLED MOUTH BREATHING

EPA Science Inventory

Nano and ultrafine particles are abundant in the atmosphere and the level of human exposure to these tiny particles is expected to increase markedly as industrial activities increase manufacturing nano-sized materials. Exposure-dose relationships and site-specific internal dose a...

Magnetic properties of Magneto-Rheological fluids with uniformly dispersed Fe nanoparticles

NASA Astrophysics Data System (ADS)

Poddar, P.; Wilson, J. L.; Srikanth, H.; Wereley, N. M.; Radhakrishnan, R.

2003-03-01

A systematic study of the magnetic properties of MR fluids containing micron-size and nano-size iron particles is presented. Nano-particles with a size range of 15-20 nm were prepared using microwave plasma technique. The MR-fluids were prepared with hydraulic oil as the carrier liquid and lecithin as an effective surfactant medium that promotes uniform particle dispersion. Static and dynamic magnetic measurements clearly indicate that the replacement of the micron-size particles by nano-particles results in a much better suspension. The magnetization in the nanoparticulate MR fluid is dominated by superparamagnetic particle response. In addition, collective behavior due to strong dipolar interactions associated with chaining of the particles in the field direction was also observed. A sharp drop in susceptibility at 250K was noted and this is ascribed to the carrier fluid freezing transition. We also present optical micrographs of showing chain formation and rheological performance as measured by field-dependent yield stress experiments. Sharper magnetic response to applied fields and lower field requirement for saturation make nano-particles attractive candidates for improved MR-fluid based sensors, actuators and microfluidics for clinical diagnostics. HS acknowledges support from NSF through grants ECS-0140047 and ECS-0102622. NMW and RR acknowledge support from NSF grant DMI-0110447.

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.

Sediment toxicity and bioaccumulation of nano and micron-sized aluminum oxide.

PubMed

Stanley, Jacob K; Coleman, Jessica G; Weiss, Charles A; Steevens, Jeffery A

2010-02-01

Nano-aluminum oxide (Al(2)O(3)) is used commercially in coatings and abrasives. Nano-Al(2)O(3) can also be generated through the oxidation of nano-aluminum in military propellants and energetics. The purpose of the present study was to assess toxicity and bioaccumulation of nano-Al(2)O(3) to a variety of sediment organisms (Tubifex tubifex, Hyalella azteca, Lumbriculus variegatus, and Corbicula fluminea). The bioaccumulation and toxicity of nano-Al(2)O(3) was compared with that of micron-sized Al(2)O(3) to investigate potential size-related effects. Results of the present study show species-specific differences in relative bioaccumulation of nano and micron-sized Al(2)O(3). Significant toxic effects (survival and growth) were observed in H. azteca testing, but only at high concentrations unlikely to be found in the environment. Nano-Al(2)O(3) was found to be more toxic than micron-sized Al(2)O(3) to H. azteca survival in a 14-d study in which organisms were in direct contact with a thin layer of 625 or 2,500 mg of Al(2)O(3) dispersed on the surface of either sediment or sand. A significant growth effect was also observed for nano but not micron-sized Al(2)O(3) at the highest treatment level tested (100 g/kg Al(2)O(3)) in a 10-d H. azteca bioassay in which Al(2)O(3) was homogenized with sediment. However, differences in measured sediment Al concentrations (micron-sized = 55.1 [+/-0.6] g/kg Al; nano-sized = 66.2 [+/-0.6] g/kg Al) in the nano and micron-sized Al(2)O(3) preclude direct comparison of the toxicity of these two treatments based on particle size. Copyright 2009 SETAC.

Deposition of ultrafine (nano) particles in the human lung.

PubMed

Asgharian, Bahman; Price, Owen T

2007-10-01

Increased production of industrial devices constructed with nanostructured materials raises the possibility of environmental and occupational human exposure with consequent adverse health effects. Ultrafine (nano) particles are suspected of having increased toxicity due to their size characteristics that serve as carrier transports. For this reason, it is critical to refine and improve existing deposition models in the nano-size range. A mathematical model of nanoparticle transport by airflow convection, axial diffusion, and convective mixing (dispersion) was developed in realistic stochastically generated asymmetric human lung geometries. The cross-sectional averaged convective-diffusion equation was solved analytically to find closed-form solutions for particle concentration and losses per lung airway. Airway losses were combined to find lobar, regional, and total lung deposition. Axial transport by diffusion and dispersion was found to have an effect on particle deposition. The primary impact was in the pulmonary region of the lung for particles larger than 10 nm in diameter. Particles below 10 nm in diameter were effectively removed from the inhaled air in the tracheobronchial region with little or no penetration into the pulmonary region. Significant variation in deposition was observed when different asymmetric lung geometries were used. Lobar deposition was found to be highest in the left lower lobe. Good agreement was found between predicted depositions of ultrafine (nano) particles with measurements in the literature. The approach used in the proposed model is recommended for more realistic assessment of regional deposition of diffusion-dominated particles in the lung, as it provides a means to more accurately relate exposure and dose to lung injury and other biological responses.

Engineering and Scaling the Spontaneous Magnetization Reversal of Faraday Induced Magnetic Relaxation in Nano-Sized Amorphous Ni Coated on Crystalline Au.

PubMed

Li, Wen-Hsien; Lee, Chi-Hung; Kuo, Chen-Chen

2016-05-28

We report on the generation of large inverse remanent magnetizations in nano-sized core/shell structure of Au/Ni by turning off the applied magnetic field. The remanent magnetization is very sensitive to the field reduction rate as well as to the thermal and field processes before the switching off of the magnetic field. Spontaneous reversal in direction and increase in magnitude of the remanent magnetization in subsequent relaxations over time were found. All of the various types of temporal relaxation curves of the remanent magnetizations are successfully scaled by a stretched exponential decay profile, characterized by two pairs of relaxation times and dynamic exponents. The relaxation time is used to describe the reduction rate, while the dynamic exponent describes the dynamical slowing down of the relaxation through time evolution. The key to these effects is to have the induced eddy current running beneath the amorphous Ni shells through Faraday induction.

Effect of Sc{sup 3+} on structural and magnetic properties of Mn-Zn nano ferrites

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

Angadi, Jagadeesha V.; Matteppanavar, Shidaling; Srinatha, N.

2016-05-23

In the present investigation, for the first time, we report on the effect of Sc{sup 3+} on the structural and magnetic properties of Mn{sub 0.5}Zn{sub 0.5}Sc{sub y}Fe{sub 2-y}O{sub 4} (y = 0.01, 0.03 and 0.05) nanoferrites synthesized by solution combustion method using the mixture of fuels. As synthesized powders were characterized for the detailed structural analysis by X-ray diffractometer (XRD), Fourier transmission infrared spectroscopy (FTIR) and room temperature magnetic properties by using vibrating sample magnetometer (VSM). The results of XRD and FTIR confirm that the formation of nano crystalline, single-phased Mn-Zn ferrite with cubic spinel structure belongs to Fd-3m spacemore » group. The room temperature magnetic studies shows that, the saturation magnetization (M{sub S}), remanence magnetization (M{sub R}) and magnetic moment (η{sub B}), magnetic particle size (D{sub m}) have found to increase with Sc{sup 3+} ion concentration up to x = 0.3 and then decrease. The values of αY-K and the magnetic particle size (D{sub m}) are found to be in the range of 68-75° and 10-19 nm respectively, with Sc{sup 3+} concentration.« less

Synthesis and characterization of Al & SiCp nano particles by non-contact ultrasonic assisted method

NASA Astrophysics Data System (ADS)

Swain, Pradyut Kumar; Das, Ratnakar; Sahoo, Ashok Kumar; Naik, Bikash; Padhi, Payodhar

2018-05-01

The present study deals with proper mixing of SiCp nano particle in the aluminum metal matrix in two stages of processing i.e. primary and secondary. During primary processing, the breaking of agglomeration of nano particles take place and these are mixed with liquid aluminum powder using high frequency(35kHz) mechanical vibration. But, during secondary processing, mixing of nano particles along with subsequent cooling take place using high frequency non contact ultrasonic method. The study also reveals that in the liquid metal nano particle were uniformly dispersed and the segregation of the particles near the grain boundaries is due to pushing of the nano particle during grain growth. The study was performed by taking aluminum as matrix and SiCp as reinforcement with weight fraction of 2% and 3% and SiCp particles sizes of 30nm each. Scanning electron microscopy(SEM) and X-ray diffraction(XRD) were conducted for characterization of nano composite material.

High surface area neodymium phosphate nano particles by modified aqueous sol-gel method

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

Sankar, Sasidharan; Warrier, Krishna Gopakumar, E-mail: wwarrierkgk@yahoo.co.in; Komban, Rajesh

2011-12-15

Graphical abstract: Synthesis of nano rod shaped neodymium phosphate particles with specific surface area as high as 107 m{sup 2} g{sup -1} and particles could be compacted and sintered at as low as 1300 Degree-Sign C to a density of 98.5% (theoretical) with an average grain size of {approx}1 {mu}m. Highlights: Black-Right-Pointing-Pointer Nano size neodymium phosphate is synthesized and characterized using a novel modified aqueous sol gel process. Black-Right-Pointing-Pointer Specific surface area above 100 m{sup 2} g{sup -1} achieved without the addition of any complexing agents. Black-Right-Pointing-Pointer High sintered density reported than the density obtained for powder synthesized through conventionalmore » solid state reaction. Black-Right-Pointing-Pointer The particles are nano sized and have rod shape morphology and are retained at higher temperatures. Black-Right-Pointing-Pointer An average grain size of {approx}1 {mu}m obtained for sintered NdPO{sub 4} after thermal etching at 1400 Degree-Sign C. -- Abstract: Synthesis of nano rod shaped neodymium phosphate (NdPO{sub 4}) particles with specific surface area as high as 107 m{sup 2}g{sup -1} and an average length of 50 nm with aspect ratio 5 was achieved using modified sol gel method. Crystallite size calculated from the X-ray diffraction data by applying Scherer equation was 5 nm for the precursor gel after calcination at 400 Degree-Sign C. NdPO{sub 4} was first precipitated from neodymium nitrate solution using phosphoric acid followed by peptization using dilute nitric acid and further gelation in ammonia atmosphere. The calcined gel powders were further characterized by surface area (Brunauer-Emmet-Teller nitrogen adsorption analysis), Transmission electron microscopy, scanning electron microscopy, UV-vis and FT-IR analysis. Transmission electron microscopy confirms the formation of rod like morphology from the sol, gel and the calcined particles in nano size range. These particles could be

NanoXCT: a novel technique to probe the internal architecture of pharmaceutical particles.

PubMed

Wong, Jennifer; D'Sa, Dexter; Foley, Matthew; Chan, John Gar Yan; Chan, Hak-Kim

2014-11-01

To demonstrate the novel application of nano X-ray computed tomography (NanoXCT) for visualizing and quantifying the internal structures of pharmaceutical particles. An Xradia NanoXCT-100, which produces ultra high-resolution and non-destructive imaging that can be reconstructed in three-dimensions (3D), was used to characterize several pharmaceutical particles. Depending on the particle size of the sample, NanoXCT was operated in Zernike Phase Contrast (ZPC) mode using either: 1) large field of view (LFOV), which has a two-dimensional (2D) spatial resolution of 172 nm; or 2) high resolution (HRES) that has a resolution of 43.7 nm. Various pharmaceutical particles with different physicochemical properties were investigated, including raw (2-hydroxypropyl)-beta-cyclodextrin (HβCD), poly (lactic-co-glycolic) acid (PLGA) microparticles, and spray-dried particles that included smooth and nanomatrix bovine serum albumin (BSA), lipid-based carriers, and mannitol. Both raw HβCD and PLGA microparticles had a network of voids, whereas spray-dried smooth BSA and mannitol generally had a single void. Lipid-based carriers and nanomatrix BSA particles resulted in low quality images due to high noise-to-signal ratio. The quantitative capabilities of NanoXCT were also demonstrated where spray-dried mannitol was found to have an average void volume of 0.117 ± 0.247 μm(3) and average void-to-material percentage of 3.5%. The single PLGA particle had values of 1993 μm(3) and 59.3%, respectively. This study reports the first series of non-destructive 3D visualizations of inhalable pharmaceutical particles. Overall, NanoXCT presents a powerful tool to dissect and observe the interior of pharmaceutical particles, including those of a respirable size.

Light absorption by coated nano-sized carbonaceous particles

NASA Astrophysics Data System (ADS)

Gangl, Martin; Kocifaj, Miroslav; Videen, Gorden; Horvath, Helmuth

The optical properties of strongly absorbing soot particles coated by transparent material are investigated experimentally and described by several modeling approaches. Soot is produced by spark discharge and passed through a Sinclair-La Mer generator where non-absorbing carnauba wax is condensed onto it to obtain internal soot-wax mixtures in a controlled way. Measurements of the extinction and volume scattering coefficient show an amplification of absorption by a factor of approximately 1.8. This behavior was described by different approaches of internally mixed materials for the modal diameters of the measured size distributions: concentric-sphere model, effective medium approximations and heterogeneous ellipsoids. The concentric-sphere model describes the absorption increase quantitatively; and hence, it is chosen to be applied to the entire particle population in the size distribution. The growth of the soot particles by condensing wax is described by a simplified growth model to estimate the different contributions of several soot particle diameters to the overall absorption cross-section.

Palm-size miniature superconducting bulk magnet

NASA Astrophysics Data System (ADS)

Saho, Norihide; Matsuda, Kazuya; Nishijima, Noriyo

The development of a small, light, powerful and energy-efficient superconducting magnet has been desired in order to realize better efficiency and manipulability in guiding magnetic nano-particles, magnetic organic cells and other items to the right place. This study focuses on the development of a high-temperature superconducting (HTS) bulk magnet characterized by comparatively low leak magnetism despite a relatively high magnetic field. On this basis, the authors developed a palm-sized superconducting bulk magnet, which is the world's smallest, lightest, and lowest power consuming, as well as a new technology to effectively magnetize such a bulk magnet in a compact Stirling-cycle cryocooler (magnet C) with a pre-magnetized HTS bulk magnet (magnet B) in a compact cryocooler. This technology is demonstrated in two steps. In the first step, magnet B is magnetized using a superconducting solenoid magnet with a high magnetic field (magnet A) via the field cooling method. In the second step, magnet C is magnetized in the high magnetic field of magnet B. The prototype magnet C weighs 1.8 kg, and measures 235 × 65 × 115 mm (L × W × H). Magnet B was magnetized to 4.9 T using a 5 T magnet, and the target, magnet C, was magnetized using magnet B so that its maximum trapped magnetic flux density reached the value of 3.15 T. The net power consumption in a steady cooling state was 23 W, which is very low and comparable to that of a laptop computer.

Effects of Particle Size and Bubble Characteristics on Transport of Micro- and Nano-Bubbles in Saturated Porous Media

NASA Astrophysics Data System (ADS)

Hamamoto, S.; Nihei, N.; Ueda, Y.; Moldrup, P.; Nishimura, T.

2016-12-01

The micro- and nano-bubbles (MNBs) have considerable potentials for the remediation of soil contaminated by organic compounds when used in conjunction with bioremediation technology. Understanding a transport mechanism of MNBs in soils is essential to optimize remediation techniques using MNBs. In this study, column transport experiments using glass beads with different size fractions (average particles size: 0.1 mm and 0.4 mm) were conducted, where MNBs created by oxygen gas were injected to the column with different flow rates. Effects of particle size and bubble characteristics on MNB transport in porous media were investigated based on the column experiments. The results showed that attachments of MNBs were enhanced under lower flow rate. Under higher flow rate condition, there were not significant differences of MNBs transport in porous media with different particle size. A convection-dispersion model including bubble attachment, detachment, and straining terms was applied to the obtained breakthrough curves for each experiment, showing good fitness against the measured data. Further investigations will be conducted to understand bubble characteristics including bubble size and zeta potential on MNB transport in porous media. Relations between in model parameters in the transport model and physical and chemical properties in porous media and MNBs will be discussed.

Synthesis and characterization of nano-sized CaCO3 in purified diet

NASA Astrophysics Data System (ADS)

Mulyaningsih, N. N.; Tresnasari, D. R.; Ramahwati, M. R.; Juwono, A. L.; Soejoko, D. S.; Astuti, D. A.

2017-07-01

The growth and development of animals depend strongly on the balanced nutrition in the diet. This research aims is to characterize the weight variations of nano-sized calcium carbonate (CaCO3) in purified diet that to be fed to animal model of rat. The nano-sized CaCO3 was prepared by milling the calcium carbonate particles for 20 hours at a rotation speed of 1000 rpm and resulting particle size in a range of 2-50 nm. Nano-sized CaCO3 added to purified diet to the four formulas that were identified as normal diet (N), deficiency calcium (DC), rich in calcium (RC), and poor calcium (PC) with containing in nano-sized CaCO3 much as 0.50 %, 0.00 %, 0.75 % and 0.25 % respectively. The nutritional content of the purified diet was proximate analyzed, it resulted as followed moisture, ash, fat, protein, crude fiber. The quantities of chemical element were analyzed by atomic absorption spectrometry (AAS), it resulted iron, magnesium, potassium and calcium. The results showed that N diet (Ca: 16,914.29 ppm) were suggested for healthy rats and RC diet (Ca: 33,696.13 ppm) for conditioned osteoporosis rats. The crystalline phases of the samples that were examined by X-ray diffraction showed that crystalline phase increased with the increasing concentration of CaCO3.

Studying the effect of particle size and coating type on the blood kinetics of superparamagnetic iron oxide nanoparticles.

PubMed

Roohi, Farnoosh; Lohrke, Jessica; Ide, Andreas; Schütz, Gunnar; Dassler, Katrin

2012-01-01

Magnetic resonance imaging (MRI), one of the most powerful imaging techniques available, usually requires the use of an on-demand designed contrast agent to fully exploit its potential. The blood kinetics of the contrast agent represent an important factor that needs to be considered depending on the objective of the medical examination. For particulate contrast agents, such as superparamagnetic iron oxide nanoparticles (SPIOs), the key parameters are particle size and characteristics of the coating material. In this study we analyzed the effect of these two properties independently and systematically on the magnetic behavior and blood half-life of SPIOs. Eleven different SPIOs were synthesized for this study. In the first set (a), seven carboxydextran (CDX)-coated SPIOs of different sizes (19-86 nm) were obtained by fractionating a broadly size-distributed CDX-SPIO. The second set (b) contained three SPIOs of identical size (50 nm) that were stabilized with different coating materials, polyacrylic acid (PAA), poly-ethylene glycol, and starch. Furthermore, small PAA-SPIOs (20 nm) were synthesized to gain a global insight into the effects of particle size vs coating characteristics. Saturation magnetization and proton relaxivity were determined to represent the magnetic and imaging properties. The blood half-life was analyzed in rats using MRI, time-domain nuclear magnetic resonance, and inductively coupled plasma optical emission spectrometry. By changing the particle size without modifying any other parameters, the relaxivity r(2) increased with increasing mean particle diameter. However, the blood half-life was shorter for larger particles. The effect of the coating material on magnetic properties was less pronounced, but it had a strong influence on blood kinetics depending on the ionic character of the coating material. In this report we systematically demonstrated that both particle size and coating material influence blood kinetics and magnetic properties of

Studying the effect of particle size and coating type on the blood kinetics of superparamagnetic iron oxide nanoparticles

PubMed Central

Roohi, Farnoosh; Lohrke, Jessica; Ide, Andreas; Schütz, Gunnar; Dassler, Katrin

2012-01-01

Purpose: Magnetic resonance imaging (MRI), one of the most powerful imaging techniques available, usually requires the use of an on-demand designed contrast agent to fully exploit its potential. The blood kinetics of the contrast agent represent an important factor that needs to be considered depending on the objective of the medical examination. For particulate contrast agents, such as superparamagnetic iron oxide nanoparticles (SPIOs), the key parameters are particle size and characteristics of the coating material. In this study we analyzed the effect of these two properties independently and systematically on the magnetic behavior and blood half-life of SPIOs. Methods: Eleven different SPIOs were synthesized for this study. In the first set (a), seven carboxydextran (CDX)-coated SPIOs of different sizes (19–86 nm) were obtained by fractionating a broadly size-distributed CDX–SPIO. The second set (b) contained three SPIOs of identical size (50 nm) that were stabilized with different coating materials, polyacrylic acid (PAA), poly-ethylene glycol, and starch. Furthermore, small PAA–SPIOs (20 nm) were synthesized to gain a global insight into the effects of particle size vs coating characteristics. Saturation magnetization and proton relaxivity were determined to represent the magnetic and imaging properties. The blood half-life was analyzed in rats using MRI, time-domain nuclear magnetic resonance, and inductively coupled plasma optical emission spectrometry. Results: By changing the particle size without modifying any other parameters, the relaxivity r2 increased with increasing mean particle diameter. However, the blood half-life was shorter for larger particles. The effect of the coating material on magnetic properties was less pronounced, but it had a strong influence on blood kinetics depending on the ionic character of the coating material. Conclusion: In this report we systematically demonstrated that both particle size and coating material influence

Multi scale modeling of ignition and combustion of micro and nano aluminum particles

NASA Astrophysics Data System (ADS)

Puri, Puneesh

With renewed interest in nano scale energetic materials like aluminum, many fundamental issues concerning the ignition and combustion characteristics at nano scales, remain to be clarified. The overall aim of the current study is the establishment of a unified theory accommodating the various processes and mechanisms involved in the combustion and ignition of aluminum particles at micro and nano scales. A comprehensive review on the ignition and combustion of aluminum particles at multi scales was first performed identifying various processes and mechanisms involved. Research focus was also placed on the establishment of a Molecular Dynamics (MD) simulation tool to investigate the characteristics of nano-particulate aluminum through three major studies. The general computational framework involved parallelized preprocessing, post-processing and main code with capability to simulate different ensembles using appropriate algorithms. Size dependence of melting temperature of pure aluminum particles was investigated in the first study. Phenomena like dynamic coexistence of solid and liquid phase and effect of surface charges on melting were explored. The second study involved the study of effect of defects in the form of voids on melting of bulk and particulate phase aluminum. The third MD study was used to analyze the thermo-mechanical behavior of nano-sized aluminum particles with total diameter of 5-10 nm and oxide thickness of 1-2.5 nm. The ensuing solid-solid and solid-liquid phase changes in the core and shell, stresses developed within the shell, and the diffusion of aluminum cations in the oxide layer, were explored in depth for amorphous and crystalline oxide layers. In the limiting case, the condition for pyrophoricity/explosivity of nano-particulate aluminum was analyzed and modified. The size dependence of thermodynamic properties at nano scales were considered and incorporated into the existing theories developed for micro and larger scales. Finally, a

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.

Nano-Sized Natural Colorants from Rocks and Soils

NASA Astrophysics Data System (ADS)

Ahmad, W. Y. W.; Ruznan, W. S.; Hamid, H. A.; Kadir, M. I. A.; Yusoh, M. K. M.; Ahmad, M. R.

2010-03-01

Colored rocks (lateritic) and soils (shales) are available in abundant all around Malaysia and they are from natural sources. The colorants will be useful if they can be transferred to substrates using dyeing, printing or brushing with acceptable fastness. First of all the rocks need to be crushed into powder form before coloration can take place. The sizes of the colorants particles obtained with coffee grinder were of 7-8 microns. They can be reduced to 3-5 micron using fluidized bed jetmill and to nano sizes with the help of planetary mono mill grinders. The experiment was conducted in both dyeing and printing of textiles using all three sizes (7-8 microns, 3-5 microns and nano sizes) of colorants on silk fabric. The colorants were applied on silk fabrics by dyeing and tie and dye techniques. In addition, the colorants can also be applied by brushing technique as in batik canting or batik block as well as silk screen printing. The evaluations of colored materials were based on the levelness of dyeing, fastness properties (washing, light and rubbing fastness) and color strength. The wash fastness testing shows that all colorants sizes have more or less the same fastness to washing but nano sized colorants produced better uniform dyes distribution (levelness of dyeing) and higher color strength.

Geometrical effects on the electron residence time in semiconductor nano-particles.

PubMed

Koochi, Hakimeh; Ebrahimi, Fatemeh

2014-09-07

We have used random walk (RW) numerical simulations to investigate the influence of the geometry on the statistics of the electron residence time τ(r) in a trap-limited diffusion process through semiconductor nano-particles. This is an important parameter in coarse-grained modeling of charge carrier transport in nano-structured semiconductor films. The traps have been distributed randomly on the surface (r(2) model) or through the whole particle (r(3) model) with a specified density. The trap energies have been taken from an exponential distribution and the traps release time is assumed to be a stochastic variable. We have carried out (RW) simulations to study the effect of coordination number, the spatial arrangement of the neighbors and the size of nano-particles on the statistics of τ(r). It has been observed that by increasing the coordination number n, the average value of electron residence time, τ̅(r) rapidly decreases to an asymptotic value. For a fixed coordination number n, the electron's mean residence time does not depend on the neighbors' spatial arrangement. In other words, τ̅(r) is a porosity-dependence, local parameter which generally varies remarkably from site to site, unless we are dealing with highly ordered structures. We have also examined the effect of nano-particle size d on the statistical behavior of τ̅(r). Our simulations indicate that for volume distribution of traps, τ̅(r) scales as d(2). For a surface distribution of traps τ(r) increases almost linearly with d. This leads to the prediction of a linear dependence of the diffusion coefficient D on the particle size d in ordered structures or random structures above the critical concentration which is in accordance with experimental observations.

Geometrical effects on the electron residence time in semiconductor nano-particles

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

Koochi, Hakimeh; Ebrahimi, Fatemeh, E-mail: f-ebrahimi@birjand.ac.ir; Solar Energy Research Group, University of Birjand, Birjand

2014-09-07

We have used random walk (RW) numerical simulations to investigate the influence of the geometry on the statistics of the electron residence time τ{sub r} in a trap-limited diffusion process through semiconductor nano-particles. This is an important parameter in coarse-grained modeling of charge carrier transport in nano-structured semiconductor films. The traps have been distributed randomly on the surface (r{sup 2} model) or through the whole particle (r{sup 3} model) with a specified density. The trap energies have been taken from an exponential distribution and the traps release time is assumed to be a stochastic variable. We have carried out (RW)more » simulations to study the effect of coordination number, the spatial arrangement of the neighbors and the size of nano-particles on the statistics of τ{sub r}. It has been observed that by increasing the coordination number n, the average value of electron residence time, τ{sup ¯}{sub r} rapidly decreases to an asymptotic value. For a fixed coordination number n, the electron's mean residence time does not depend on the neighbors' spatial arrangement. In other words, τ{sup ¯}{sub r} is a porosity-dependence, local parameter which generally varies remarkably from site to site, unless we are dealing with highly ordered structures. We have also examined the effect of nano-particle size d on the statistical behavior of τ{sup ¯}{sub r}. Our simulations indicate that for volume distribution of traps, τ{sup ¯}{sub r} scales as d{sup 2}. For a surface distribution of traps τ{sup ¯}{sub r} increases almost linearly with d. This leads to the prediction of a linear dependence of the diffusion coefficient D on the particle size d in ordered structures or random structures above the critical concentration which is in accordance with experimental observations.« less

Light extinction method for diagnostics of particles sizes formed in magnetic field

NASA Astrophysics Data System (ADS)

Myshkin, Vyacheslav; Izhoykin, Dmitry; Grigoriev, Alexander; Gamov, Denis; Leonteva, Daria

2018-03-01

The results of laser diagnostics of dispersed particles formed upon cooling of Zn vapor are presented. The radiation attenuation in the wavelength range 420-630 nm with a step of 0.3 nm was registered. The attenuation coefficients spectral dependence was processed using known algorithms for integral equation solving. The 10 groups of 8 attenuation coefficients were formed. Each group was processed taking with considering of previous decisions. After processing of the 10th group of data, calculations were repeated from the first one. Data of the particles sizes formed in a magnetic field of 0, 44 and 76 mT are given. A model of physical processes in a magnetic field is discussed.

[Preparation and release exam of magnetic chitosan nano-spheres of doxorubicin].

PubMed

Han, Tao; Xiao, Qingping; Zhang, Yuanming

2010-02-01

Magnetic chitosan (CS) nano-spheres were prepared by the modified suspension cross-linking technique. The results demonstrated that the magnetic drug nano-spheres are mainly spherical in form with a size of 200 to 800 nm, and show good magnetic responsivity. Here, Doxorubicin was used as exam drug. Glutaraldehyde connects Doxorubicin to CS by the chemical bond (-N = C-), and the drug content is in range of 1% to 15% (w/w). The chemical bond is broken depending on pH, so pH is the important factor for the release of doxorubicin. The doxorubicin release was 22.0%, 13.4%, and 4.1% in the space of 7d, when pH was 1, 2, 4. So the nano-spheres are pH-sensitive magnetic targeting drug micro-spheres.

Bias field tunable magnetic configuration and magnetization dynamics in Ni80Fe20 nano-cross structures with varying arm length

NASA Astrophysics Data System (ADS)

Adhikari, K.; Choudhury, S.; Mandal, R.; Barman, S.; Otani, Y.; Barman, A.

2017-01-01

Ferromagnetic nano-cross structures promise exotic static magnetic configurations and very rich and tunable magnetization dynamics leading towards potential applications in magnetic logic and communication devices. Here, we report an experimental study of external magnetic field tunable static magnetic configurations and magnetization dynamics in Ni80Fe20 nano-cross structures with varying arm lengths (L). Broadband ferromagnetic resonance measurements showed a strong variation in the number of spin-wave (SW) modes and mode frequencies (f) with bias field magnitude (H). Simulated static magnetic configurations and SW mode profiles explain the rich variation of the SW spectra, including mode softening, mode crossover, mode splitting, and mode merging. Such variation of SW spectra is further modified by the size of the nano-cross. Remarkably, with decreasing arm length of nano-cross structures, the onion magnetization ground state becomes more stable. Calculated magnetostatic field distributions support the above observations and revealed the non-collective nature of the dynamics in closely packed nano-cross structures. The latter is useful for their possible applications in magnetic storage and memory devices.

Solid oxide fuel cell cathode infiltrate particle size control and oxygen surface exchange resistance determination

NASA Astrophysics Data System (ADS)

Burye, Theodore E.

Over the past decade, nano-sized Mixed Ionic Electronic Conducting (MIEC) -- micro-sized Ionic Conducting (IC) composite cathodes produced by the infiltration method have received much attention in the literature due to their low polarization resistance (RP) at intermediate (500-700°C) operating temperatures. Small infiltrated MIEC oxide nano-particle size and low intrinsic MIEC oxygen surface exchange resistance (Rs) have been two critical factors allowing these Nano-Micro-Composite Cathodes (NMCCs) to achieve high performance and/or low temperature operation. Unfortunately, previous studies have not found a reliable method to control or reduce infiltrated nano-particle size. In addition, controversy exists on the best MIEC infiltrate composition because: 1) Rs measurements on infiltrated MIEC particles are presently unavailable in the literature, and 2) bulk and thin film Rs measurements on nominally identical MIEC compositions often vary by up to 3 orders of magnitude. Here, two processing techniques, precursor nitrate solution desiccation and ceria oxide pre-infiltration, were developed to systematically produce a reduction in the average La0.6Sr0.4Co0.8Fe 0.2O3-delta (LSCF) infiltrated nano-particle size from 50 nm to 22 nm. This particle size reduction reduced the SOFC operating temperature, (defined as the temperature where RP=0.1 Ocm 2) from 650°C to 540°C. In addition, Rs values for infiltrated MIEC particles were determined for the first time through finite element modeling calculations on 3D Focused Ion Beam-Scanning Electron Microscope (FIB-SEM) reconstructions of electrochemically characterized infiltrated electrodes.

Effect of particle size on band gap and DC electrical conductivity of TiO2 nanomaterial

NASA Astrophysics Data System (ADS)

Avinash, B. S.; Chaturmukha, V. S.; Jayanna, H. S.; Naveen, C. S.; Rajeeva, M. P.; Harish, B. M.; Suresh, S.; Lamani, Ashok R.

2016-05-01

Materials reduced to the Nano scale can exhibit different properties compared to what they exhibit on a micro scale, enabling unique applications. When TiO2 is reduced to Nano scale it shows unique properties, of which the electrical aspect is highly important. This paper presents increase in the energy gap and decrease in conductivity with decrease in particle size of pure Nano TiO2 synthesized by hydrolysis and peptization of titanium isopropoxide. Aqueous solution with various pH and peptizing the resultant suspension will form Nano TiO2 at different particle sizes. As the pH of the solution is made acidic reduction in the particle size is observed. And it is confirmed from XRD using Scherer formula and SEM, as prepared samples are studied for UV absorbance, and DC conductivity from room temperature to 400°C. From the tauc plot it was observed, and calculated the energy band gap increases as the particle size decreases and shown TiO2 is direct band gap. From Arrhenius plot clearly we encountered, decrease in the conductivity for the decrease in particle size due to hopping of charge carriers and it is evident that, we can tailor the band gap by varying particle size.

Effect of pulsed and continuous ultrasound on structural and magnetic properties of nano-sized Ni0.4Cu0.2Zn0.4Fe2O4 ferrite

NASA Astrophysics Data System (ADS)

Hassen, Harzali; Adel, Megriche; Arbi, Mgaidi

2018-03-01

Ultrasound-assisted co-precipitation has been used to prepare nano-sized Ni0.4Cu0.2Zn0.4Fe2O4 ferrite. Continuous (C-US) and pulsed (P-US) ultrasound modes are used at constant frequency = 20 kHz, reaction time = 2 h and pulse durations of 10 s on and 10 s off. All experiments were conducted at two temperatures 90 and 100°C. Samples were characterized by X-ray diffraction (XRD), Fourier transform spectroscopy (FT-IR), N2 adsorption isotherms at 77 k analysis (BET), transmission electron microscopy (TEM) and vibrating sample magnetometry (VSM) techniques. A nanocrystalline single-phase with particle size in the range 12-18 nm is obtained in both modes: continuous and pulsed ultrasound mode. FT-IR measurements show two absorption bands assigned to the tetrahedral and octahedral vibrations (ν1 and ν2) characteristics of cubic spinel ferrite. The specific surface area (S BET) is in the range of 110-140 m2 g-1 and an average pore size between 5.5 and 6.5 nm. The lowest values are obtained in pulsed mode. Finally, this work shows that the magnetic properties are affected by the ultrasound conditions, without affecting the particle shape. The saturation magnetization (Ms) values obtained for all samples are comparable. In P-US mode, the saturation magnetization (Ms) increases as temperature increases. Moreover, P-US mode opens a new avenue for synthesis of NiCuZn ferrites.

Adsorption of Heavy Metals in Industrial Wastewater by Magnetic Nano-particles

NASA Astrophysics Data System (ADS)

Tu, Y.; You, C.

2010-12-01

Industrial wastewater containing heavy metals is of great concern because of their toxic impact to living species and environments. Removal of metal ions from industrial effluent using nano-particles is an area of extensive research. This study collected wastewaters and effluents from 11 industrial companies in tanning, electronic plating, printed circuit board manufacturing, semi-conductor, and metal surface treatment industry and studied in detailed the major and trace element compositions to develop potential fingerprinting technique for pollutant source identification. The results showed that electronic plating and metal surface treatment industry produce high Fe, Mn, Cr, Zn, Ni and Mo wastewater. The tanning industry and the printed circuit board manufacturing industry released wastewater with high Fe and Cr, Cu and Ni, respectively. For semi-conductor industry, significant dissolved In was detected in wastewater. The absorption experiments to remove heavy metals in waters were conducted using Fe3O4 nano-particles. Under optimal conditions, more than 99 % dissolved metals were removed in a few minutes.

Elemental selenium particles at nano-size (Nano-Se) are more toxic to Medaka (Oryzias latipes) as a consequence of hyper-accumulation of selenium: a comparison with sodium selenite.

PubMed

Li, Hongcheng; Zhang, Jinsong; Wang, Thanh; Luo, Wenru; Zhou, Qunfang; Jiang, Guibin

2008-09-29

Recent studies have shown that elemental selenium particles at nano-size (Nano-Se) exhibited comparable bioavailability and less toxicity in mice and rats when compared to sodium selenite, selenomethinine and methylselenocysteine. However, little is known about the toxicity profile of Nano-Se in aquatic animals. In the present study, toxicities of Nano-Se and selenite in selenium-sufficient Medaka fish were compared. Selenium bioaccumulation and subsequent clearance in fish livers, gills, muscles and whole bodies were examined after 10 days of exposure to Nano-Se and selenite (100 microg Se/L) and again after 7 days of depuration. Both forms of selenium exposure effectively increased selenium concentrations in the investigated tissues. Surprisingly, Nano-Se was found to be more hyper-accumulated in the liver compared to selenite with differences as high as sixfold. Selenium clearance of both Nano-Se and selenite occurred at similar ratios in whole bodies and muscles but was not rapidly cleared from livers and gills. Nano-Se exhibited strong toxicity for Medaka with an approximately fivefold difference in terms of LC(50) compared to selenite. Nano-Se also caused larger effects on oxidative stress, most likely due to more hyper-accumulation of selenium in liver. The present study suggests that toxicity of nanoparticles can largely vary between different species and concludes that the evaluation of nanotoxicology should be carried out on a case-by-case basis.

Detection of bisphenol A using palm-size NanoAptamer analyzer.

PubMed

Lim, Hyun Jeong; Chua, Beelee; Son, Ahjeong

2017-08-15

We have demonstrated a palm-size NanoAptamer analyzer capable of detecting bisphenol A (BPA) at environmentally relevant concentrations (<1ng/mL or ppb). It is designed for performing reaction and fluorescence measurement on single cuvette sample. Modified NanoGene assay was used as the sensing mechanism where signaling DNA and QD 655 was tethered to QD 565 and magnetic bead via the aptamer. Aptamer affinity with BPA resulted in the release of the signaling DNA and QD 655 from the complex and hence corresponding decrease in QD 655 fluorescence measurement signal. Baseline characterization was first performed with empty cuvettes, quantum dots and magnetic beads under near-ideal conditions to establish essential functionality of the NanoAptamer analyzer. Duration of incubation time, number of rinse cycles, and necessity of cuvette vibration were also investigated. In order to demonstrate the capability of the NanoAptamer analyzer to detect BPA, samples with BPA concentrations ranging from 0.0005 to 1.0ng/mL (ppb) were used. The performance of the NanoAptamer analyzer was further examined by using laboratory protocol and commercial spectrofluorometer as reference. Correlation between NanoAptamer analyzer and laboratory protocol as well as commercial spectrofluorometer was evaluated via correlation plots and correlation coefficients. Copyright © 2017 Elsevier B.V. All rights reserved.

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.

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.

Effects of exposure to nano and bulk sized TiO2 and CuO in Lemna minor.

PubMed

Dolenc Koce, Jasna

2017-10-01

Nanoparticles of TiO 2 and CuO are among most commonly used nanoparticles, and elevated concentrations of them are expected to be found in all environments, including aquatic. A standard growth inhibition test ISO/CD 20079 was used to determine the toxicity of nano sized and larger micro sized (bulk) particles in the concentrations of 0.1, 1, 10, 100 and 1000 μM CuO and TiO 2 on common duckweed (Lemna minor L.). Both nano and bulk CuO particles caused changes in the structure and function of treated plants. The number of fronds and colonies decreased by as much as 78%, the length of roots and fronds decreased by 99% and 14%, respectively. Furthermore, photochemical efficiency was reduced by up to 35%, and the activities of antioxidative enzymes guaiacol peroxidase, ascorbate peroxidase and glutathione reductase increased by more than 240%. The altered physiological state of the CuO exposed plants was also reflected in the elevated occurrence of necrosis and bleaching in the duckweed colonies. Nano sized particles of CuO proved more phytotoxic than bulk particles, and the effects of both studied CuO sizes were concentration dependent. On the other hand, both bulk and nano sized particles of TiO 2 caused no severe phytotoxic effects, there was no concentration dependence and they could be considered as non-harmful to common duckweed. Copyright © 2017 Elsevier Masson SAS. All rights reserved.

Mass production of polymer nano-wires filled with metal nano-particles.

PubMed

Lomadze, Nino; Kopyshev, Alexey; Bargheer, Matias; Wollgarten, Markus; Santer, Svetlana

2017-08-17

Despite the ongoing progress in nanotechnology and its applications, the development of strategies for connecting nano-scale systems to micro- or macroscale elements is hampered by the lack of structural components that have both, nano- and macroscale dimensions. The production of nano-scale wires with macroscale length is one of the most interesting challenges here. There are a lot of strategies to fabricate long nanoscopic stripes made of metals, polymers or ceramics but none is suitable for mass production of ordered and dense arrangements of wires at large numbers. In this paper, we report on a technique for producing arrays of ordered, flexible and free-standing polymer nano-wires filled with different types of nano-particles. The process utilizes the strong response of photosensitive polymer brushes to irradiation with UV-interference patterns, resulting in a substantial mass redistribution of the polymer material along with local rupturing of polymer chains. The chains can wind up in wires of nano-scale thickness and a length of up to several centimeters. When dispersing nano-particles within the film, the final arrangement is similar to a core-shell geometry with mainly nano-particles found in the core region and the polymer forming a dielectric jacket.

Magnetofluidic concentration and separation of non-magnetic particles using two magnet arrays

PubMed Central

Hejazian, Majid

2016-01-01

The present paper reports the use of diluted ferrofluid and two arrays of permanent magnets for the size-selective concentration of non-magnetic particles. The micro magnetofluidic device consists of a straight channels sandwiched between two arrays of permanent magnets. The permanent magnets create multiple capture zones with minimum magnetic field strength along the channel. The complex interaction between magnetic forces and hydrodynamic force allows the device to operate in different regimes suitable for concentration of non-magnetic particles with small difference in size. Our experimental results show that non-magnetic particles with diameters of 3.1 μm and 4.8 μm can be discriminated and separated with this method. The results from this study could be used as a guide for the design of size-sensitive separation devices for particle and cell based on negative magnetophoresis. PMID:27478527

Preparation of nano fluids by mechanical method

NASA Astrophysics Data System (ADS)

Boopathy, J.; Pari, R.; Kavitha, M.; Angelo, P. C.

2012-07-01

Nanofluids are conventional heat transfer fluids that contain nano particles of metals, oxides, carbides, nitrides, or nanotubes. Nanofluids exhibit enhanced thermal conductivity and heat transfer coefficients compared to the base fluids. This paper presents the procedure for preparing nanofluids consisting of Copper and Aluminium nano powders in base fluids. Copper and Aluminium nano powders were produced by planetary ball wet milling at 300rpm for 50hrs. Toluene was added to ensure wet milling. These powders were characterized in XRD and SEM for their purity, particle size and shape. The XRD results confirmed the final particle sizes of Copper and Aluminium in the nano range. Then the 0.01 gm of nano metal powders was added in 150 ml of double distilled water and magnetic stirring was done at 1500 rpm for 15 minutes. Sodium lauryl sulphate (0.05%) was added in water as surfactant to ensure the stability of the dispersion. Ultrasonication in the 3000 watts bath was done for 10 minutes to enhance the uniform dispersion of metal powders in water. The pH, dynamic viscosity, ionic conductivity and the stability of the fluids were determined for further usage of synthesized nanofluids as coolant during grinding operation.

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

PubMed

Peters, Ruud; Kramer, Evelien; Oomen, Agnes G; Rivera, Zahira E Herrera; Oegema, Gerlof; Tromp, Peter C; Fokkink, Remco; Rietveld, Anton; Marvin, Hans J P; Weigel, Stefan; Peijnenburg, Ad A C M; Bouwmeester, Hans

2012-03-27

The presence, dissolution, agglomeration state, and release of materials in the nano-size range from food containing engineered nanoparticles during human digestion is a key question for the safety assessment of these materials. We used an in vitro model to mimic the human digestion. Food products subjected to in vitro digestion included (i) hot water, (ii) coffee with powdered creamer, (iii) instant soup, and (iv) pancake which either contained silica as the food additive E551, or to which a form of synthetic amorphous silica or 32 nm SiO(2) particles were added. The results showed that, in the mouth stage of the digestion, nano-sized silica particles with a size range of 5-50 and 50-500 nm were present in food products containing E551 or added synthetic amorphous silica. However, during the successive gastric digestion stage, this nano-sized silica was no longer present for the food matrices coffee and instant soup, while low amounts were found for pancakes. Additional experiments showed that the absence of nano-sized silica in the gastric stage can be contributed to an effect of low pH combined with high electrolyte concentrations in the gastric digestion stage. Large silica agglomerates are formed under these conditions as determined by DLS and SEM experiments and explained theoretically by the extended DLVO theory. Importantly, in the subsequent intestinal digestion stage, the nano-sized silica particles reappeared again, even in amounts higher than in the saliva (mouth) digestion stage. These findings suggest that, upon consumption of foods containing E551, the gut epithelium is most likely exposed to nano-sized silica. © 2012 American Chemical Society

Effect of magnetic anisotropy and particle size distribution on temperature dependent magnetic hyperthermia in Fe3O4 ferrofluids

NASA Astrophysics Data System (ADS)

Palihawadana Arachchige, Maheshika; Nemala, Humeshkar; Naik, Vaman; Naik, Ratna

Magnetic hyperthermia (MHT) has a great potential as a non-invasive cancer therapy technique. Specific absorption rate (SAR) which measures the efficiency of heat generation, mainly depends on magnetic properties of nanoparticles such as saturation magnetization (Ms) and magnetic anisotropy (K) which depend on the size and shape. Therefore, MHT applications of magnetic nanoparticles often require a controllable synthesis to achieve desirable magnetic properties. We have synthesized Fe3O4 nanoparticles using two different methods, co-precipitation (CP) and hydrothermal (HT) techniques to produce similar XRD crystallite size of 12 nm, and subsequently coated with dextran to prepare ferrofluids for MHT. However, TEM measurements show average particle sizes of 13.8 +/-3.6 nm and 14.6 +/-3.6 nm for HT and CP samples, implying the existence of an amorphous surface layer for both. The MHT data show the two samples have very different SAR values of 110 W/g (CP) and 40W/g (HT) at room temperature, although they have similar Ms of 70 +/-4 emu/g regardless of their different TEM sizes. We fitted the temperature dependent SAR using linear response theory to explain the observed results. CP sample shows a larger magnetic core with a narrow size distribution and a higher K value compared to that of HT sample.

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

NASA Astrophysics Data System (ADS)

Siegmann, Stephan; Leparoux, Marc; Rohr, Lukas

2005-06-01

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

'Nano-immuno test' for the detection of live Mycobacterium avium subspecies paratuberculosis bacilli in the milk samples using magnetic nano-particles and chromogen.

PubMed

Singh, Manju; Singh, Shoor Vir; Gupta, Saurabh; Chaubey, Kundan Kumar; Stephan, Bjorn John; Sohal, Jagdip Singh; Dutta, Manali

2018-04-26

Early rapid detection of Mycobacterium avium subspecies paratuberculosis (MAP) bacilli in milk samples is the major challenge since traditional culture method is time consuming and laboratory dependent. We report a simple, sensitive and specific nano-technology based 'Nano-immuno test' capable of detecting viable MAP bacilli in the milk samples within 10 h. Viable MAP bacilli were captured by MAP specific antibody-conjugated magnetic nano-particles using resazurin dye as chromogen. Test was optimized using true culture positive (10-bovine and 12-goats) and true culture negative (16-bovine and 25-goats) raw milk samples. Domestic livestock species in India are endemically infected with MAP. After successful optimization, sensitivity and specificity of the 'nano-immuno test' in goats with respect to milk culture was 91.7% and 96.0%, respectively. Whereas, it was 90.0% (sensitivity) and 92.6% (specificity) with respect to IS900 PCR. In bovine milk samples, sensitivity and specificity of 'nano-immuno test' with respect to milk culture was 90.0% and 93.7%, respectively. However, with respect to IS900 PCR, the sensitivity and specificity was 88.9% and 94.1%, respectively. Test was validated with field raw milk samples (goats-258 and bovine-138) collected from domestic livestock species to detect live/viable MAP bacilli. Of 138 bovine raw milk samples screened by six diagnostic tests, 81 (58.7%) milk samples were positive for MAP infection in one or more than one diagnostic tests. Of 81 (58.7%) positive bovine raw milk samples, only 24 (17.4%) samples were detected positive for the presence of viable MAP bacilli. Of 258 goats raw milk samples screened by six diagnostic tests, 141 (54.6%) were positive for MAP infection in one or more than one test. Of 141 (54.6%) positive raw milk samples from goats, only 48 (34.0%) were detected positive for live MAP bacilli. Simplicity and efficiency of this novel 'nano-immuno test' makes it suitable for wide-scale screening of milk

Chemical speciation of size-segregated floor dusts and airborne magnetic particles collected at underground subway stations in Seoul, Korea.

PubMed

Jung, Hae-Jin; Kim, BoWha; Malek, Md Abdul; Koo, Yong Sung; Jung, Jong Hoon; Son, Youn-Suk; Kim, Jo-Chun; Kim, HyeKyoung; Ro, Chul-Un

2012-04-30

Previous studies have reported the major chemical species of underground subway particles to be Fe-containing species that are generated from wear and friction processes at rail-wheel-brake and catenaries-pantographs interfaces. To examine chemical composition of Fe-containing particles in more details, floor dusts were collected at five sampling locations of an underground subway station. Size-segregated floor dusts were separated into magnetic and non-magnetic fractions using a permanent magnet. Using X-ray diffraction (XRD) and scanning electron microscopy/energy dispersive X-ray spectrometry (SEM/EDX), iron metal, which is relatively harmless, was found to be the dominating chemical species in the floor dusts of the <25 μm size fractions with minor fractions of Mg, Al, Si, Ca, S, and C. From SEM analysis, the floor dusts of the <25 μm size fractions collected on railroad ties appeared to be smaller than 10 μm, indicating that their characteristics should somewhat reflect the characteristics of airborne particles in the tunnel and the platform. As most floor dusts are magnetic, PM levels at underground subway stations can be controlled by removing magnetic indoor particles using magnets. In addition, airborne subway particles, most of which were smaller than 10 μm, were collected using permanent magnets at two underground subway stations, namely Jegi and Yangjae stations, in Seoul, Korea. XRD and SEM/EDX analyses showed that most of the magnetic aerosol particles collected at Jegi station was iron metal, whereas those at Yangjae station contained a small amount of Fe mixed with Na, Mg, Al, Si, S, Ca, and C. The difference in composition of the Fe-containing particles between the two subway stations was attributed to the different ballast tracks used. Copyright © 2012 Elsevier B.V. All rights reserved.

Theoretical and experimental study on the effects of particle size and temperature on the reaction kinetics of cubic nano-Cu2O

NASA Astrophysics Data System (ADS)

Tang, Huanfeng; Huang, Zaiyin; Xiao, Ming; Liang, Min; Chen, Liying; Tan, XueCai

2017-09-01

The activities, selectivities, and stabilities of nanoparticles in heterogeneous reactions are size-dependent. In order to investigate the influencing laws of particle size and temperature on kinetic parameters in heterogeneous reactions, cubic nano-Cu2O particles of four different sizes in the range of 40-120 nm have been controllably synthesized. In situ microcalorimetry has been used to attain thermodynamic data on the reaction of Cu2O with aqueous HNO3 and, combined with thermodynamic principles and kinetic transition-state theory, the relevant reaction kinetic parameters have been evaluated. The size dependences of the kinetic parameters are discussed in terms of the established kinetic model and the experimental results. It was found that the reaction rate constants increased with decreasing particle size. Accordingly, the apparent activation energy, pre-exponential factor, activation enthalpy, activation entropy, and activation Gibbs energy decreased with decreasing particle size. The reaction rate constants and activation Gibbs energies increased with increasing temperature. Moreover, the logarithms of the apparent activation energies, pre-exponential factors, and rate constants were found to be linearly related to the reciprocal of particle size, consistent with the kinetic models. The influence of particle size on these reaction kinetic parameters may be explained as follows: the apparent activation energy is affected by the partial molar enthalpy, the pre-exponential factor is affected by the partial molar entropy, and the reaction rate constant is affected by the partial molar Gibbs energy. [Figure not available: see fulltext.

Comparison on exfoliated graphene nano-sheets and triturated graphite nano-particles for mode-locking the Erbium-doped fibre lasers

NASA Astrophysics Data System (ADS)

Yang, Chun-Yu; Lin, Yung-Hsiang; Wu, Chung-Lun; Cheng, Chih-Hsien; Tsai, Din-Ping; Lin, Gong-Ru

2018-06-01

Comparisons on exfoliated graphene nano-sheets and triturated graphite nano-particles for mode-locking the Erbium-doped fiber lasers (EDFLs) are performed. As opposed to the graphite nano-particles obtained by physically triturating the graphite foil, the tri-layer graphene nano-sheets is obtained by electrochemically exfoliating the graphite foil. To precisely control the size dispersion and the layer number of the exfoliated graphene nano-sheet, both the bias of electrochemical exfoliation and the speed of centrifugation are optimized. Under a threshold exfoliation bias of 3 volts and a centrifugation at 1000 rpm, graphene nano-sheets with an average diameter of 100  ±  40 nm can be obtained. The graphene nano-sheets with an area density of 15 #/µm2 are directly imprinted onto the end-face of a single-mode fiber made patchcord connector inside the EDFL cavity. Such electrochemically exfoliated graphene nano-sheets show comparable saturable absorption with standard single-graphene and perform the self-amplitude modulation better than physically triturated graphite nano-particles. The linear transmittance and modulation depth of the inserted graphene nano-sheets are 92.5% and 53%, respectively. Under the operation with a power gain of 21.5 dB, the EDFL can be passively mode-locked to deliver a pulsewidth of 454.5 fs with a spectral linewidth of 5.6 nm. The time-bandwidth product of 0.31 is close to the transform limit. The Kelly sideband frequency spacing of 1.34 THz is used to calculate the chirp coefficient as  ‑0.0015.

Solution-processed photodetectors from colloidal silicon nano/micro particle composite.

PubMed

Tu, Chang-Ching; Tang, Liang; Huang, Jiangdong; Voutsas, Apostolos; Lin, Lih Y

2010-10-11

We demonstrate solution-processed photodetectors composed of heavy-metal-free Si nano/micro particle composite. The colloidal Si particles are synthesized by electrochemical etching of Si wafers, followed by ultra-sonication to pulverize the porous surface. With alkyl ligand surface passivation through hydrosilylation reaction, the particles can form a stable colloidal suspension which exhibits bright photoluminescence under ultraviolet excitation and a broadband extinction spectrum due to enhanced scattering from the micro-size particles. The efficiency of the thin film photodetectors has been substantially improved by preventing oxidation of the particles during the etching process.

Effective heating of magnetic nanoparticle aggregates for in vivo nano-theranostic hyperthermia.

PubMed

Wang, Chencai; Hsu, Chao-Hsiung; Li, Zhao; Hwang, Lian-Pin; Lin, Ying-Chih; Chou, Pi-Tai; Lin, Yung-Ya

2017-01-01

Magnetic resonance (MR) nano-theranostic hyperthermia uses magnetic nanoparticles to target and accumulate at the lesions and generate heat to kill lesion cells directly through hyperthermia or indirectly through thermal activation and control releasing of drugs. Preclinical and translational applications of MR nano-theranostic hyperthermia are currently limited by a few major theoretical difficulties and experimental challenges in in vivo conditions. For example, conventional models for estimating the heat generated and the optimal magnetic nanoparticle sizes for hyperthermia do not accurately reproduce reported in vivo experimental results. In this work, a revised cluster-based model was proposed to predict the specific loss power (SLP) by explicitly considering magnetic nanoparticle aggregation in in vivo conditions. By comparing with the reported experimental results of magnetite Fe 3 O 4 and cobalt ferrite CoFe 2 O 4 magnetic nanoparticles, it is shown that the revised cluster-based model provides a more accurate prediction of the experimental values than the conventional models that assume magnetic nanoparticles act as single units. It also provides a clear physical picture: the aggregation of magnetic nanoparticles increases the cluster magnetic anisotropy while reducing both the cluster domain magnetization and the average magnetic moment, which, in turn, shift the predicted SLP toward a smaller magnetic nanoparticle diameter with lower peak values. As a result, the heating efficiency and the SLP values are decreased. The improvement in the prediction accuracy in in vivo conditions is particularly pronounced when the magnetic nanoparticle diameter is in the range of ~10-20 nm. This happens to be an important size range for MR cancer nano-theranostics, as it exhibits the highest efficacy against both primary and metastatic tumors in vivo. Our studies show that a relatively 20%-25% smaller magnetic nanoparticle diameter should be chosen to reach the maximal

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

NASA Astrophysics Data System (ADS)

Li, Bo; Guo, Bo; Fan, Hongsong; Zhang, Xingdong

2008-11-01

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

Shielding properties of the ordinary concrete loaded with micro- and nano-particles against neutron and gamma radiations.

PubMed

Mesbahi, Asghar; Ghiasi, Hosein

2018-06-01

The shielding properties of ordinary concrete doped with some micro and nano scaled materials were studied in the current study. Narrow beam geometry was simulated using MCNPX Monte Carlo code and the mass attenuation coefficient of ordinary concrete doped with PbO 2 , Fe 2 O 3 , WO 3 and H 4 B (Boronium) in both nano and micro scales was calculated for photon and neutron beams. Mono-energetic beams of neutrons (100-3000 keV) and photons (142-1250 keV) were used for calculations. The concrete doped with nano-sized particles showed higher neutron removal cross section (7%) and photon attenuation coefficient (8%) relative to micro-particles. Application of nano-sized material in the composition of new concretes for dual protection against neutrons and photons are recommended. For further studies, the calculation of attenuation coefficients of these nano-concretes against higher energies of neutrons and photons and different particles are suggested. Copyright © 2018 Elsevier Ltd. All rights reserved.

Recovery of Neodymium from Aqueous Solution Using Magnetic Nano-particles

NASA Astrophysics Data System (ADS)

Tu, Y. J.; You, C. F.; Lo, S. C.

2015-12-01

This study investigates the recovery of spiked Nd from seawater media by magnetic nano-particles Fe3O4. A rapid increase of Nd recovery from 0.06 to 23.6 mg g-1 was observed when the solution pH adjusted from 2.01 to 8.18 at 298 K. A maxima Nd adsorption capacity was estimated to be 25.02 mg g-1 at 308 K and 8.18 pH. A negative change in standard free energy (ΔGo = -5.87, -6.69, -7.68 kJ mol-1 at 288, 298, and 308 K, respectively) suggests that Nd adsorption is spontaneous. The positive ΔHo value (2.42 kJ mol-1) supports its endothermic nature of the adsorption and agrees with the observed enhanced Nd adsorption at high temperatures. Besides, the positive ΔSo (10.84 J mol-1 K-1) displays that the randomness increase at the solid-solution interface during Nd adsorption. More importantly, we observed that the Nd adsorption only decreased slightly while the NaCl ionic strength increased from 0.001 to 1.0 N, implying the involvement of inner-sphere mechanism. These data indicated that the adsorbent of ferrite has a great potential in selective and fast recovery of spiked Nd from seawater matrix.

Modifications in Glass Ionomer Cements: Nano-Sized Fillers and Bioactive Nanoceramics

PubMed Central

Najeeb, Shariq; Khurshid, Zohaib; Zafar, Muhammad Sohail; Khan, Abdul Samad; Zohaib, Sana; Martí, Juan Manuel Nuñez; Sauro, Salvatore; Matinlinna, Jukka Pekka; Rehman, Ihtesham Ur

2016-01-01

Glass ionomer cements (GICs) are being used for a wide range of applications in dentistry. In order to overcome the poor mechanical properties of glass ionomers, several modifications have been introduced to the conventional GICs. Nanotechnology involves the use of systems, modifications or materials the size of which is in the range of 1–100 nm. Nano-modification of conventional GICs and resin modified GICs (RMGICs) can be achieved by incorporation of nano-sized fillers to RMGICs, reducing the size of the glass particles, and introducing nano-sized bioceramics to the glass powder. Studies suggest that the commercially available nano-filled RMGIC does not hold any significant advantage over conventional RMGICs as far as the mechanical and bonding properties are concerned. Conversely, incorporation of nano-sized apatite crystals not only increases the mechanical properties of conventional GICs, but also can enhance fluoride release and bioactivity. By increasing the crystallinity of the set matrix, apatites can make the set cement chemically more stable, insoluble, and improve the bond strength with tooth structure. Increased fluoride release can also reduce and arrest secondary caries. However, due to a lack of long-term clinical studies, the use of nano-modified glass ionomers is still limited in daily clinical dentistry. In addition to the in vitro and in vivo studies, more randomized clinical trials are required to justify the use of these promising materials. The aim of this paper is to review the modification performed in GIC-based materials to improve their physicochemical properties. PMID:27428956

Continual model of magnetic dynamics for antiferromagnetic particles in analyzing size effects on Morin transition in hematite nanoparticles

NASA Astrophysics Data System (ADS)

Mishchenko, I.; Chuev, M.; Kubrin, S.; Lastovina, T.; Polyakov, V.; Soldatov, A.

2018-05-01

Alternative explanation to the effect of disappearance of the Morin transition on hematite nanoparticles with their size decreasing is proposed basing on an idea of the predominant role of the shape anisotropy for nanosize particles. Three types of the magnetic structure of hematite nanoparticles with various sizes are found by Mössbauer spectroscopy: coexistence of the well-pronounced antiferromagnetic and weakly ferromagnetic phases for particles with average diameters of about 55 nm, non-uniform distribution of the magnetization axes which concentrate on the vicinity of the basal plane (111) for prolonged particles with cross sections of about 20 nm, and uniform distribution of the easy axes in regard to the crystalline directions for 3-nm particles. Description of the temperature evolution of experimental data within novel model of the magnetic dynamics for antiferromagnetic particles which accounts the exchange, relativistic, and anisotropy interactions is provided, and the structural as well as energy characteristics of the studied systems are reconstructed.

Particle Size Distribution of Heavy Metals and Magnetic Susceptibility in an Industrial Site.

PubMed

Ayoubi, Shamsollah; Soltani, Zeynab; Khademi, Hossein

2018-05-01

This study was conducted to explore the relationships between magnetic susceptibility and some soil heavy metals concentrations in various particle sizes in an industrial site, central Iran. Soils were partitioned into five fractions (< 28, 28-75, 75-150, 150-300, and 300-2000 µm). Heavy metals concentrations including Zn, Pb, Fe, Cu, Ni and Mn and magnetic susceptibility were determined in bulk soil samples and all fractions in 60 soil samples collected from the depth of 0-5 cm. The studied heavy metals except for Pb and Fe displayed a substantial enrichment in the < 28 µm. These two elements seemed to be independent of the selected size fractions. Magnetic minerals are specially linked with medium size fractions including 28-75, 75-150 and 150-300 µm. The highest correlations were found for < 28 µm and heavy metals followed by 150-300 µm fraction which are susceptible to wind erosion risk in an arid environment.

Saturn's Icy satellites: The Role of Sub-Micron Ice Particles and Nano-sized Contaminants (Invited)

NASA Astrophysics Data System (ADS)

Clark, R. N.; Cruikshank, D. P.; Dalle Ore, C. M.; Jaumann, R.; Brown, R. H.; Stephan, K.; Buratti, B. J.; Filacchione, G.; Baines, K. H.; Nicholson, P.

2010-12-01

The Visual and Infrared Mapping Spectrometer (VIMS) has obtained spatially resolved imaging spectroscopy data on numerous satellites of Saturn. The spectral trends on individual satellites and as compositional gradients within the Saturn system show systematic trends that indicate variable ice grain sizes and contaminants. Compositional mapping shows that the satellite surfaces are composed largely of H2O ice, with small amounts of CO2, trace organics, bound water or OH-bearing minerals, and possible signatures of ammonia, H2O or OH-bearing minerals, and dark, fine-grained materials. The E-ring coats the inner satellites with sub-micron ice particles. The Cassini Rev 49 Iapetus fly-by on September 10, 2007, provided imaging spectroscopy data on both the dark material and the transition zone between the dark material and the visually bright ice on the trailing side. The dark material has very low albedo with a linear increase in reflectance with wavelength, a 3-micron water absorption, and a CO2 absorption. The only reflectance models that can explain the trends include highly absorbing sub-micron materials that create Rayleigh absorption. Radiative transfer models that include diffraction from Rayleigh scattering and Rayleigh absorption are necessary to match observed data. The dark material is well matched by a high component of fine-grained metallic iron plus a small component of nano-phase hematite. Spatially resolved Iapetus data show mixing of dark material with ice and the mixtures display a blue scattering peak and a UV absorption. The blue scattering peak and UV-Visible absorption is observed in spectra of all satellites at some locations where dark material is mixed with the ice. Rayleigh scattering and Rayleigh absorption have also been observed in spectral properties of the Earth's moon. Rayleigh absorption requires high absorption coefficient nano-sized particles, which is also consistent with metallic iron. The UV absorber appears to have increased

Selective laser processing of ink-jet printed nano-scaled tin-clad copper particles

NASA Astrophysics Data System (ADS)

Yung, K. C.; Plura, T. S.

2010-11-01

The deposition of tin-clad nano-size copper particles was carried out by means of ink-jet printing. Curing the particles on Polyimide (PI) turned them into soldered structures using an Nd-YAG laser. Area coverage of 55% was achieved for a single-layer print. Subsequent laser sintering increased this value to 95%. A Butanol-based copper ink and an aqueous tin (Sn)-clad Copper (Cu) ink were produced and were ink-jetted in this work. These nano-metallic inks showed excellent suspension stability with particle weight concentrations as high as 5%. The ink components were examined by measuring the particle size distribution in a dispersed condition, and the melting temperature. A piezo ink-jet print head was used to deposit the inks onto a moveable substrate. The thermal effect of the laser irradiation allowed approaching and connecting adjacent particles by melting the particle’s tin coating. The results were examined with regard to structure and soldering properties using EDX, SEM and optical microscopy.

Improvement of the tool life of a micro-end mill using nano-sized SiC/Ni electroplating method.

PubMed

Park, Shinyoung; Kim, Kwang-Su; Roh, Ji Young; Jang, Gyu-Beom; Ahn, Sung-Hoon; Lee, Caroline Sunyong

2012-04-01

High mechanical properties of a tungsten carbide micro-end-mill tool was achieved by extending its tool life by electroplating nano-sized SiC particles (< 100 nm) that had a hardness similar to diamond in a nickel-based material. The co-electroplating method on the surface of the micro-end-mill tool was applied using SiC particles and Ni particles. Organic additives (saccharin and ammonium chloride) were added in a Watts bath to improve the nickel matrix density in the electroplating bath and to smooth the surface of the co-electroplating. The morphology of the coated nano-sized SiC particles and the composition were measured using Scanning Electron Microscope and Energy Dispersive Spectrometer. As the Ni/SiC co-electroplating layer was applied, the hardness and friction coefficient improved by 50%. Nano-sized SiC particles with 7 wt% were deposited on the surface of the micro-end mill while the Ni matrix was smoothed by adding organic additives. The tool life of the Ni/SiC co-electroplating coating on the micro-end mill was at least 25% longer than that of the existing micro-end mills without Ni/SiC co-electroplating. Thus, nano-sized SiC/Ni coating by electroplating significantly improves the mechanical properties of tungsten carbide micro-end mills.

Effects of nano-SiO{sub 2} particles on surface tracking characteristics of silicone rubber composites

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

Liu, Yong, E-mail: tjuliuyong@tju.edu.cn; Li, Zhonglei; Du, Boxue

Compared with neat silicone rubber composites (SiRCs), SiRCs filled with nano-sized SiO{sub 2} particles at weight ratios from 0.1 to 1.0 wt. % exhibit a higher surface flashover voltage and a greater resistance to surface tracking. Scanning electron microscopy images of tracking morphologies indicate that the SiO{sub 2} particles are situated in close proximity to the polymeric chains and act as bridges to stabilize the chains and maintain the structure of the composite. Higher concentrations of nano-sized SiO{sub 2} particles, however, (above 0.3 wt. %) produce defects in the molecular network which lead to reductions in both the surface flashover voltage and the resistancemore » to surface tracking, although these reduced values are still superior to those of neat SiRCs. Therefore, SiRCs filled with nano-sized SiO{sub 2} particles, especially at an optimal weight ratio (0.1 to 0.3 wt. %), may have significant potential applications as outdoor insulators for power systems.« less

Neuroprotective effect of curcumin-loaded lactoferrin nano particles against rotenone induced neurotoxicity.

PubMed

Bollimpelli, V Satish; Kumar, Prashant; Kumari, Sonali; Kondapi, Anand K

2016-05-01

Curcumin is known to have neuroprotective role and possess antioxidant, anti-inflammatory activities. Rotenone, a flavonoid induced neurotoxicity in dopaminergic cells is being widely studied in Parkinson's Disease (PD) research. In the present study, curcumin loaded lactoferrin nano particles prepared by sol-oil chemistry were used to protect dopaminergic cell line SK-N-SH against rotenone induced neurotoxicity. These curcumin loaded nano particles were of 43-60 nm diameter size and around 100 nm hydrodynamic size as assessed by transmission electron microscopy, atomic force microscopy and dynamic light scattering analysis respectively. The encapsulation efficiency was 61.3% ± 2.4%. Cellular uptake of curcumin through these nano particles was confirmed by confocal imaging and spectrofluorimetric analysis. The curcumin loaded lactoferrin nanoparticles showed greater intracellular drug uptake, sustained retention and greater neuroprotection than soluble counterpart. Neuroprotective activity was characterized through viability assays and by estimating ROS levels. Furthermore rotenone induced PD like features were characterized by decrease in tyrosine hydroxylase expression and increase in α-synuclein expression. Taken together curcumin loaded lactoferrin nanoparticles could be a promising drug delivery strategy against neurotoxicity in dopaminergic neurons. Copyright © 2016 Elsevier Ltd. All rights reserved.

Quantifying the motion of magnetic particles in excised tissue: Effect of particle properties and applied magnetic field

NASA Astrophysics Data System (ADS)

Kulkarni, Sandip; Ramaswamy, Bharath; Horton, Emily; Gangapuram, Sruthi; Nacev, Alek; Depireux, Didier; Shimoji, Mika; Shapiro, Benjamin

2015-11-01

This article presents a method to investigate how magnetic particle characteristics affect their motion inside tissues under the influence of an applied magnetic field. Particles are placed on top of freshly excised tissue samples, a calibrated magnetic field is applied by a magnet underneath each tissue sample, and we image and quantify particle penetration depth by quantitative metrics to assess how particle sizes, their surface coatings, and tissue resistance affect particle motion. Using this method, we tested available fluorescent particles from Chemicell of four sizes (100 nm, 300 nm, 500 nm, and 1 μm diameter) with four different coatings (starch, chitosan, lipid, and PEG/P) and quantified their motion through freshly excised rat liver, kidney, and brain tissues. In broad terms, we found that the applied magnetic field moved chitosan particles most effectively through all three tissue types (as compared to starch, lipid, and PEG/P coated particles). However, the relationship between particle properties and their resulting motion was found to be complex. Hence, it will likely require substantial further study to elucidate the nuances of transport mechanisms and to select and engineer optimal particle properties to enable the most effective transport through various tissue types under applied magnetic fields.

Powder XRD, TEM, FTIR and thermal studies of strontium tartrate nano particles

NASA Astrophysics Data System (ADS)

Lathiya, U. M.; Jethva, H. O.; Joshi, M. J.; Vyas, P. M.

2017-05-01

Strontium tartrate finds several applications, e.g., as non-linear optical and dielectric material, in tracer composition and ammunition unit, in treating structural integrity of bone. The growth of single crystals of strontium tartrate in silica gel has been widely reported. In the present study, strontium tartrate nano particles were synthesized by wet chemical method using strontium chloride, tartaric acid and sodium meta-silicate solutions in the presence of Triton X -100 surfactant. It was found that the presence of sodium meta-silicate facilitated the reaction for strontium tartrate product. The powder XRD study of strontium tartrate nano-particles suggested monoclinic crystal system and the average crystallite size was found to be 40 nm determined by applying Scherrer's formula. The TEM analysis indicated that the nano particles were spherical in nature. The FTIR spectrum confirmed the presence of various functional groups such as O-H,C-H, and C=O stretching mode. The thermal analysis was carried out by using TGA and DTA studies. The nano-particles were found to be stable up to 175°C and then decomposed through various stages. The results are compared with the bulk crystalline material available in the literature.

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

Nano-fabricated size exclusion chromatograph

NASA Technical Reports Server (NTRS)

Svehla, D.; Feldman, S.; Feldman, J.; Grunthaner, F.; Shakkottai, P.; Castillo, L. del; White, V.

2002-01-01

This paper describes the development of a nano-fabricated size exclusion chromatograph (nSEC) based on the principle that molecules traveling through amicrocolumn containing nano-fabricated features will have characteristic elution times that directly correlate to molecular weight. Compared to conventional size exclusion chromatography, the nSEC offers greater control over the size exclusion process; mass fabrication; integration of the separation column with associated valves, pumps, and detectors; and dramatic reductions in instrument mass and power requirements.

Enhanced thermal effect using magnetic nano-particles during high-intensity focused ultrasound.

PubMed

Devarakonda, Surendra Balaji; Myers, Matthew R; Giridhar, Dushyanth; Dibaji, Seyed Ahmad Reza; Banerjee, Rupak Kumar

2017-01-01

Collateral damage and long sonication times occurring during high-intensity focused ultrasound (HIFU) ablation procedures limit clinical advancement. In this reserarch, we investigated whether the use of magnetic nano-particles (mNPs) can reduce the power required to ablate tissue or, for the same power, reduce the duration of the procedure. Tissue-mimicking phantoms containing embedded thermocouples and physiologically acceptable concentrations (0%, 0.0047%, and 0.047%) of mNPs were sonicated at acoustic powers of 5.2 W, 9.2 W, and 14.5 W, for 30 seconds. Lesion volumes were determined for the phantoms with and without mNPs. It was found that with the 0.047% mNP concentration, the power required to obtain a lesion volume of 13 mm3 can be halved, and the time required to achieve a 21 mm3 lesion decreased by a factor of 5. We conclude that mNPs have the potential to reduce damage to healthy tissue, and reduce the procedure time, during tumor ablation using HIFU.

Structure of Nano-sized CeO 2 Materials: Combined Scattering and Spectroscopic Investigations

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

Marchbank, Huw R.; Clark, Adam H.; Hyde, Timothy I.

Here, the nature of nano-sized ceria, CeO 2, systems were investigated using neutron and X-ray diffraction and X-ray absorption spectroscopy. Whilst both diffraction andtotal pair distribution functions (PDFs) revealed that in all the samples the occupancy of both Ce 4+ and O 2- are very close to the ideal stoichiometry, the analysis using reverse Monte Carlo technique revealedsignificant disorder around oxygen atoms in the nano sized ceria samples in comparison to the highly crystalline NIST standard.In addition, the analysis reveal that the main differences observed in the pair correlations from various X-ray and neutron diffraction techniques were attributed to themore » particle size of the CeO 2 prepared by the reported three methods. Furthermore, detailed analysis of the Ce L 3– and K-edge EXAFS data support this finding; in particular the decrease in higher shell coordination numbers with respect to the NIST standard, are attributed to differences in particle size.« less

Structure of Nano-sized CeO 2 Materials: Combined Scattering and Spectroscopic Investigations

DOE PAGES

Marchbank, Huw R.; Clark, Adam H.; Hyde, Timothy I.; ...

2016-08-29

Here, the nature of nano-sized ceria, CeO 2, systems were investigated using neutron and X-ray diffraction and X-ray absorption spectroscopy. Whilst both diffraction andtotal pair distribution functions (PDFs) revealed that in all the samples the occupancy of both Ce 4+ and O 2- are very close to the ideal stoichiometry, the analysis using reverse Monte Carlo technique revealedsignificant disorder around oxygen atoms in the nano sized ceria samples in comparison to the highly crystalline NIST standard.In addition, the analysis reveal that the main differences observed in the pair correlations from various X-ray and neutron diffraction techniques were attributed to themore » particle size of the CeO 2 prepared by the reported three methods. Furthermore, detailed analysis of the Ce L 3– and K-edge EXAFS data support this finding; in particular the decrease in higher shell coordination numbers with respect to the NIST standard, are attributed to differences in particle size.« less

Review on characterization of nano-particle emissions and PM morphology from internal combustion engines: Part 2 [Review on morphology and nanostructure characterization of nano-particle emission from internal combustion engines

DOE PAGES

Choi, Seungmok; Myung, C. L.; Park, S.

2014-03-05

This study presents a review of the characterization of physical properties, morphology, and nanostructure of particulate emissions from internal combustion engines. Because of their convenience and readiness of measurement, various on-line commercial instruments have been used to measure the mass, number, and size distribution of nano-particles from different engines. However, these on-line commercial instruments have inherent limitations in detailed analysis of chemical and physical properties, morphology, and nanostructure of engine soot agglomerates, information that is necessary to understand the soot formation process in engine combustion, soot particle behavior in after-treatment systems, and health impacts of the nano-particles. For these reasons,more » several measurement techniques used in the carbon research field, i.e., highresolution transmission electron microscopy (HRTEM), X-ray diffraction (XRD), and Raman spectroscopy, were used for analysis of engine particulate matter (PM). This review covers a brief introduction of several measurement techniques and previous results from engine nano-particle characterization studies using those techniques.« less

Superconducting properties of nano-sized SiO2 added YBCO thick film on Ag substrate

NASA Astrophysics Data System (ADS)

Almessiere, Munirah Abdullah; Al-Otaibi, Amal lafy; Azzouz, Faten Ben

2017-10-01

The microstructure and the flux pinning capability of SiO2-added YBa2Cu3Oy thick films on Ag substrates were investigated. A series of YBa2Cu3Oy thick films with small amounts (0-0.5 wt%) of nano-sized SiO2 particles (12 nm) was prepared. The thicknesses of the prepared thick films was approximately 100 µm. Phase analysis by x-ray diffraction and microstructure examination by scanning electron microscopy were performed and the critical current density dependence on the applied magnetic field Jc(H) and electrical resistivity ρ(T) were investigated. The magnetic field and temperature dependence of the critical current density (Jc) was calculated from magnetization measurements using Bean's critical state model. The results showed that the addition of a small amount (≤0.02 wt%) of SiO2 was effective in enhancing the critical current densities in the applied magnetic field. The sample with 0.01 wt% of added SiO2 exhibited a superconducting characteristics under an applied magnetic field for a temperature ranging from 10 to 77 K.

The magnetic particle plume solar sail concept

NASA Astrophysics Data System (ADS)

Knuth, William H.

2000-01-01

A magnetic particle space radiator was proposed in the late 1950s as a means to dissipate waste heat from space nuclear systems. The concept was a plume of hot magnetic particles confined to and traversing a magnetic field produced by super conducting magnets in the space vehicle. The large surface area of the hot particles was expected to effectively radiate away the heat. The cooling particles followed along the lines of the magnetic field and eventually returned to the vehicle where they again picked up a fresh charge of waste heat for return out to the plume. This paper presents a new concept for consideration. The same basic magnetic particle plume idea is proposed in this paper, except the purpose of the plume would be to receive momentum (and possibly electric power) from the solar wind in the manner of a solar sail. Recent nano-technologies allow the magnetic particles to be 2-3 orders of magnitude smaller than envisioned for the heat radiator, and the magnetic field would be stronger than we envisioned in the '50s. The application of the magnetic solar sail would be for propelling space-faring vehicles on long duration exploration of the solar system and possibly beyond. A first look is provided at the elements of the system, together with an estimate of the thrust potential and the approximate weights of the system. The system appears to have the potential to develop on the order of 50lb and 100lb of thrust and weight on the order of 15,000lb .

Nano red elemental selenium has no size effect in the induction of seleno-enzymes in both cultured cells and mice.

PubMed

Zhang, Jinsong; Wang, Huali; Bao, Yongping; Zhang, Lide

2004-05-28

We previous reported that a nano red elemental selenium (Nano-Se) in the range from 20 approximately 60 nm had similar bioavailability to sodium selenite (BioFactors 15 (2001) 27). We recently found that Nano-Se with different size had marked difference in scavenging an array of free radicals in vitro, the smaller the particle, the better scavenging activity (Free Radic. Biol. Med. 35 (2003) 805). In order to examine whether there is a size effect of Nano-Se in the induction of Se-dependent enzymes, a range of Nano-Se (5 approximately 200 nm) have been prepared based on the control of elemental Se atom aggregation. The sizes of Nano-Se particles were inversely correlated with protein levels in the redox system of selenite and glutathione. Different sizes of red elemental Se were prepared by adding varying amount of bovine serum albumin (BSA). Three different sizes of Nano-Se (5 approximately 15 nm, 20 approximately 60 nm, and 80 approximately 200 nm) have been chosen for the comparison of biological activity in terms of the induction of seleno-enzyme activities. Results showed that there was no significant size effect of Nano-Se from 5 to 200 nm in the induction of glutathione peroxidase (GPx), phospholipid hydroperoxide glutathione peroxidase (PHGPx) and thioredoxin reductase-1 (TrxR-1) in human hepatoma HepG2 cells and the livers of mice.

Comparative study of three magnetic nano-particles (FeSO4, FeSO4/SiO2, FeSO4/SiO2/TiO2) in plasmid DNA extraction.

PubMed

Rahnama, H; Sattarzadeh, A; Kazemi, F; Ahmadi, N; Sanjarian, F; Zand, Z

2016-11-15

Recent updates on Magnetic Nano-Particles (MNPs) based separation of nucleic acids have received more attention due to their easy manipulation, simplicity, ease of automation and cost-effectiveness. It has been indicated that DNA molecules absorb on solid surfaces via hydrogen-bonding, and hydrophobic and electrostatic interactions. These properties highly depend on the surface condition of the solid support. Therefore, surface modification of MNPs may enhance their functionality and specification. In the present study, we functionalized Fe3O4 nano-particle surface utilizing SiO2 and TiO2 layer as Fe3O4/SiO2 and Fe3O4/SiO2/TiO2 and then compare their functionality in the adsorption of plasmid DNA molecules with the naked Fe3O4 nano-particles. The result obtained showed that the purity and amount of DNA extracted by Fe3O4 coated by SiO2 or SiO2/TiO2 were higher than the naked Fe3O4 nano-particles. Furthermore, we obtained pH 8 and 1.5 M NaCl as an optimal condition for desorption of DNA from MNPs. The result further showed that, 0.2 mg nano-particle and 10 min at 55 °C are the optimal conditions for DNA desorption from nano-particles. In conclusion, we recommended Fe3O4/SiO2/TiO2 as a new MNP for separation of DNA molecules from biological sources. Copyright © 2016 Elsevier Inc. All rights reserved.

Magnetic hyperthermia in magnetic nanoemulsions: Effects of polydispersity, particle concentration and medium viscosity

NASA Astrophysics Data System (ADS)

Lahiri, B. B.; Ranoo, Surojit; Zaibudeen, A. W.; Philip, John

2017-11-01

Magnetic fluid hyperthermia (MFH) is a promising cancer treatment modality where alternating magnetic field is used for heating cancerous cells loaded with magnetic nanofluids. Of late, it is realized that magnetic nano-carriers in the size range ∼100-200 nm (e.g. magnetic nanocomposites, magnetic liposomes and magnetic nanoemulsions) are ideal candidates for multimodal MFH coupled with drug delivery or photodynamic therapy due to enhanced permeation and retention (EPR) in the leaky vasculature of cancerous tissues. Here, we study the radiofrequency alternating magnetic field induced heating in magnetically polarizable oil-in-water nanoemulsions of hydrodynamic diameter ∼200 nm, containing single domain superparamagnetic nanoparticles of average diameter ∼10 nm in the oil phase. We probe the effects of size polydispersity of the droplets and medium viscosity on the field induced heating efficiency. The contribution of Neel and Brown relaxation of the magnetic nanoparticles on specific absorption rate (SAR) of the magnetic nanoemulsions, was found to increase linearly with the square of the applied field, with a maximum value of 164.4 ± 4.3 W/gFe. In magnetic nanoemulsions, the heating is induced by the Neel-Brown relaxation of the MNP over a length scale of 10 nm, and the whole scale Brownian relaxation of the emulsion droplets has over a length scale of 200 nm. The magnetic nanoemulsion sample with lower polydispersity (σ = 0.2) exhibited a significantly higher SAR value (3.3 times higher) as compared to the sample with larger polydispersity (σ = 0.4). The SAR values of the samples with 4.6 and 1.7 wt.% of MNP loading with σ values 0.4 a 0.3, respectively were comparable, suggesting a higher heating efficiency in nanofluid containing particles of lower size polydispersity even at lower particle loading. The emulsion droplets, immobilized in an agar matrix (4 wt.%), gave a maximum SAR value of 41.7 ± 2.4 W/gFe as compared to 111.8 ± 3.4 W/gFe in the

Electrical, thermal, catalytic and magnetic properties of nano-structured materials and their applications

NASA Astrophysics Data System (ADS)

Liu, Zuwei

Nanotechnology is a subject that studies the fabrication, properties, and applications of materials on the nanometer-scale. Top-down and bottom-up approaches are commonly used in nano-structure fabrication. The top-down approach is used to fabricate nano-structures from bulk materials by lithography, etching, and polishing etc. It is commonly used in mechanical, electronic, and photonic devices. Bottom-up approaches fabricate nano-structures from atoms or molecules by chemical synthesis, self-assembly, and deposition, such as sol-gel processing, molecular beam epitaxy (MBE), focused ion beam (FIB) milling/deposition, chemical vapor deposition (CVD), and electro-deposition etc. Nano-structures can have several different dimensionalities, including zero-dimensional nano-structures, such as fullerenes, nano-particles, quantum dots, nano-sized clusters; one-dimensional nano-structures, such as carbon nanotubes, metallic and semiconducting nanowires; two-dimensional nano-structures, such as graphene, super lattice, thin films; and three-dimensional nano-structures, such as photonic structures, anodic aluminum oxide, and molecular sieves. These nano-structured materials exhibit unique electrical, thermal, optical, mechanical, chemical, and magnetic properties in the quantum mechanical regime. Various techniques can be used to study these properties, such as scanning probe microscopy (SPM), scanning/transmission electron microscopy (SEM/TEM), micro Raman spectroscopy, etc. These unique properties have important applications in modern technologies, such as random access memories, display, solar energy conversion, chemical sensing, and bio-medical devices. This thesis includes four main topics in the broad area of nanoscience: magnetic properties of ferro-magnetic cobalt nanowires, plasmonic properties of metallic nano-particles, photocatalytic properties of titanium dioxide nanotubes, and electro-thermal-optical properties of carbon nanotubes. These materials and their

Effect of particle size on ferroelectric and magnetic properties of BiFeO₃ nanopowders.

PubMed

Escobar Castillo, M; Shvartsman, V V; Gobeljic, D; Gao, Y; Landers, J; Wende, H; Lupascu, D C

2013-09-06

The ferroelectric and magnetic behaviour of multiferroic BiFeO₃ nanoparticles has been studied using piezoresponse force microscopy (PFM), Mössbauer spectroscopy and SQUID magnetometry. The results of the PFM studies indicate a decay of the spontaneous polarization with decreasing particle size. Nevertheless, particles with diameter ∼50 nm still manifest ferroelectric behaviour. At the same time these particles are weakly ferromagnetic. The Mössbauer spectroscopy studies prove that the weak ferromagnetic state is due to non-compensated surface spins rather than distortions of the cycloidal spin structure characteristic for bulk BiFeO₃.

Effect of drying environment on grain size of titanium dioxide nano-powder synthesized via sol-gel method

NASA Astrophysics Data System (ADS)

Zandi, Pegah; Hosseini, Elham; Rashchi, Fereshteh

2018-01-01

Titanium dioxide Nano powder has been synthesized from titanium isopropoxide (TTIP) in chloride media by sol-gel method. In this research, the effect of the drying environment, from air to oven drying at 100 °C, calcination time and temperature on nano TiO2 grain size was investigated. The synthesized powder was analyzed by x-ray diffraction and scanning electron microscope. Based on the results, the powder has been crystallized in anatase and rutile phases, due to different calcination temperatures. At temperatures above 600 °C, the Titanium dioxide nano powder has been crystallized as rutile. The crystalline structure of titanium dioxide nano powder changed because of the different calcination temperatures and time applied. The average particle size of the powder dried in air was larger than the powder dried in oven. The minimum particle size of the powder dried in air was 50 nm and in the oven was 9 nm, observed and calculated Williamson-Hall equation. All in all, with overall increasing of calcination time and temperature the grain size increased. Moreover, in the case of temperature, after a certain temperature, the grain size became constant and didn't change significantly.

Superhydrophobic and transparent coatings prepared by self-assembly of dual-sized silica particles

NASA Astrophysics Data System (ADS)

Xu, Qian-Feng; Wang, Jian-Nong

2010-06-01

Superhydrophobic and transparent coatings have been prepared by self-assembly of dual-sized silica particles from a mixed dispersion. The desirable micro/nano hierarchical structure for superhydrophobicity is constructed simply by adjusting the size and ratio of the dual-sized particles without organic/inorganic templates. The transparency of the prepared coatings is also researched, and the light scattering can be reduced by lowering the ratio of big sub-micro particles while the superhydrophobicity maintains unchanged. When nano particles with a diameter of 50 nm and sub-micro particles with a diameter of 350 nm are assembled, a superhydrophobic property with a water contact angle of 161° is achieved. Additionally, the coated glass is also very transparent. The highest transmittance of the coated glass can reach 85%. Compared to traditional colloid self-assembly approach, which often involves dozens of steps of layer-by-layer processing and organic/inorganic templates, the present approach is much simpler and has advantages for large-scale coating.

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.

Effective heating of magnetic nanoparticle aggregates for in vivo nano-theranostic hyperthermia

PubMed Central

Wang, Chencai; Hsu, Chao-Hsiung; Li, Zhao; Hwang, Lian-Pin; Lin, Ying-Chih; Chou, Pi-Tai; Lin, Yung-Ya

2017-01-01

Magnetic resonance (MR) nano-theranostic hyperthermia uses magnetic nanoparticles to target and accumulate at the lesions and generate heat to kill lesion cells directly through hyperthermia or indirectly through thermal activation and control releasing of drugs. Preclinical and translational applications of MR nano-theranostic hyperthermia are currently limited by a few major theoretical difficulties and experimental challenges in in vivo conditions. For example, conventional models for estimating the heat generated and the optimal magnetic nanoparticle sizes for hyperthermia do not accurately reproduce reported in vivo experimental results. In this work, a revised cluster-based model was proposed to predict the specific loss power (SLP) by explicitly considering magnetic nanoparticle aggregation in in vivo conditions. By comparing with the reported experimental results of magnetite Fe3O4 and cobalt ferrite CoFe2O4 magnetic nanoparticles, it is shown that the revised cluster-based model provides a more accurate prediction of the experimental values than the conventional models that assume magnetic nanoparticles act as single units. It also provides a clear physical picture: the aggregation of magnetic nanoparticles increases the cluster magnetic anisotropy while reducing both the cluster domain magnetization and the average magnetic moment, which, in turn, shift the predicted SLP toward a smaller magnetic nanoparticle diameter with lower peak values. As a result, the heating efficiency and the SLP values are decreased. The improvement in the prediction accuracy in in vivo conditions is particularly pronounced when the magnetic nanoparticle diameter is in the range of ~10–20 nm. This happens to be an important size range for MR cancer nano-theranostics, as it exhibits the highest efficacy against both primary and metastatic tumors in vivo. Our studies show that a relatively 20%–25% smaller magnetic nanoparticle diameter should be chosen to reach the maximal

Nano-sized calcium phosphate particles for periodontal gene therapy.

PubMed

Elangovan, Satheesh; Jain, Shardool; Tsai, Pei-Chin; Margolis, Henry C; Amiji, Mansoor

2013-01-01

Growth factors such as platelet-derived growth factor (PDGF) have significantly enhanced periodontal therapy outcomes with a high degree of variability, mostly due to the lack of continual supply for a required period of time. One method to overcome this barrier is gene therapy. The aim of this in vitro study is to evaluate PDGF-B gene delivery in fibroblasts using nano-sized calcium phosphate particles (NCaPP) as vectors. NCaPP incorporating green fluorescent protein (NCaPP-GFP) and PDGF-B (NCaPP-PDGF-B) plasmids were synthesized using an established precipitation system and characterized using transmission electron microscopy and 1.2% agarose gel electrophoresis. Biocompatibility and transfection of the nanoplexes in fibroblasts were evaluated using cytotoxicity assay and florescence microscopy, respectively. Polymerase chain reaction and enzyme-linked immunosorbent assay were performed to evaluate PDGF-B transfection after different time points of treatments, and the functionality of PDGF-B transfection was evaluated using the cell proliferation assay. Synthesized NCaPP nanoplexes incorporating the genes of GFP and PDGF-B were spherical in shape and measured about 30 to 50 nm in diameter. Gel electrophoresis confirmed DNA incorporation and stability within the nanoplexes, and 3-(4,5-dimethylthiazol-2-yl)-5-(3-carboxymethoxyphenyl)-2-(4-sulfophenyl)-2H-tetrazolium reagent assay demonstrated their biocompatibility in fibroblasts. In vitro transfection studies revealed a higher and longer lasting transfection after NCaPP-PDGF-B treatment, which lasted up to 96 hours. Significantly enhanced fibroblast proliferation observed in NCaPP-PDGF-B-treated cells confirmed the functionality of these nanoplexes. NCaPP demonstrated higher levels of biocompatibility and efficiently transfected PDGF plasmids into fibroblasts under described in vitro conditions.

Effects of micro-sized and nano-sized WO3 on mass attenauation coefficients of concrete by using MCNPX code.

PubMed

Tekin, H O; Singh, V P; Manici, T

2017-03-01

In the present work the effect of tungsten oxide (WO 3 ) nanoparticles on mass attenauation coefficients of concrete has been investigated by using MCNPX (version 2.4.0). The validation of generated MCNPX simulation geometry has been provided by comparing the results with standard XCOM data for mass attenuation coefficients of concrete. A very good agreement between XCOM and MCNPX have been obtained. The validated geometry has been used for definition of nano-WO 3 and micro-WO 3 into concrete sample. The mass attenuation coefficients of pure concrete and WO 3 added concrete with micro-sized and nano-sized have been compared. It was observed that shielding properties of concrete doped with WO 3 increased. The results of mass attenauation coefficients also showed that the concrete doped with nano-WO 3 significanlty improve shielding properties than micro-WO 3 . It can be concluded that addition of nano-sized particles can be considered as another mechanism to reduce radiation dose. Copyright © 2016 Elsevier Ltd. All rights reserved.

A review on preparation of silver nano-particles

NASA Astrophysics Data System (ADS)

Haider, Adawiya J.; Haider, Mohammad J.; Mehde, Mohammad S.

2018-05-01

The term "nano particle" (NP) refers to particle diameter in nanometers in size. Nanoparticles contain a small number of constituent atoms or molecules that differ from the properties inherent in their bulk counterparts, found in various forms such as spherical, triangular, cubic, pentagonal, rod-shaped, shells, elliptical and so on. In this chapter, it has been presented the theoretical concepts of the preparation of AgNPS as powders and collide nanoparticles, techniques of preparation with their characterization (morphology, sign charge and potential value, particle distribution ….etc.). Also, included unique properties of AgNPS that are different from those of their bulk materials like: High surface area to volume ratio effects Quantization of electronic and vibration properties.

Meissner effect measurement of single indium particle using a customized on-chip nano-scale superconducting quantum interference device system

NASA Astrophysics Data System (ADS)

Wu, Long; Chen, Lei; Wang, Hao; Liu, Xiaoyu; Wang, Zhen

2017-04-01

As many emergent phenomena of superconductivity appear on a smaller scale and at lower dimension, commercial magnetic property measurement systems (MPMSs) no longer provide the sensitivity necessary to study the Meissner effect of small superconductors. The nano-scale superconducting quantum interference device (nano-SQUID) is considered one of the most sensitive magnetic sensors for the magnetic characterization of mesoscopic or microscopic samples. Here, we develop a customized on-chip nano-SQUID measurement system based on a pulsed current biasing method. The noise performance of our system is approximately 4.6 × 10-17 emu/Hz1/2, representing an improvement of 9 orders of magnitude compared with that of a commercial MPMS (~10-8 emu/Hz1/2). Furthermore, we demonstrate the measurement of the Meissner effect of a single indium (In) particle (of 47 μm in diameter) using our on-chip nano-SQUID system. The system enables the observation of the prompt superconducting transition of the Meissner effect of a single In particle, thereby providing more accurate characterization of the critical field Hc and temperature Tc. In addition, the retrapping field Hre as a function of temperature T of single In particle shows disparate behavior from that of a large ensemble.

Using DNA-labelled nano- and microparticles to track particle transport in the environment

NASA Astrophysics Data System (ADS)

McNew, Coy; Wang, Chaozi; Dahlke, Helen; Lyon, Steve; Walter, Todd

2017-04-01

By utilizing bio-molecular nanotechnology developed for nano-medicines and drug delivery, we are able to produce DNA-labelled nano- and microparticle tracers for use in a myriad of environmental systems. The use of custom sequenced DNA allows for the fabrication of an enormous number of uniquely labelled tracers with identical transport properties (approximately 1.61 x 1060 unique sequences), each independently quantifiable, that can be applied simultaneously in any hydrologic system. By controlling the fabrication procedure to produce particles of custom size and charge, we are able to tag each size-charge combination uniquely in order to directly probe the effect of these variables on the transport properties of the particles. Here we present our methods for fabrication, extraction, and analysis of the DNA nano- and microparticle tracers, along with results from several successful applications of the tracers, including transport and retention analysis at the lab, continuum, and field scales. To date, our DNA-labelled nano- and microparticle tracers have proved useful in surface and subsurface water applications, soil retention, and even subglacial flow pathways. The range of potential applications continue to prove nearly limitless.

Characterization of nano-sized oxides in Fe-12Cr oxide-dispersion-strengthened ferritic steel using small-angle neutron scattering

NASA Astrophysics Data System (ADS)

Han, Young-Soo; Mao, Xiaodong; Jang, Jinsung; Kim, Tae-Kyu

2015-04-01

The ferritic ODS steel was manufactured by hot isostatic pressing and heat treatment. The nano-sized microstructures such as yttrium oxides and Cr oxides were quantitatively analyzed by small-angle neutron scattering (SANS). The effects of the fabrication conditions on the nano-sized microstructure were investigated in relation to the quantitative analysis results obtained by SANS. The ratio between magnetic and nuclear scattering components was calculated, and the characteristics of the nano-sized yttrium oxides are discussed based on the SANS analysis results.

Synthesis and characterization of CaCO3 (calcite) nano particles from cockle shells (Anadara granosa Linn) by precipitation method

NASA Astrophysics Data System (ADS)

Widyastuti, Sri; Intan Ayu Kusuma, P.

2017-06-01

Calcium supplements can reduce the risk of osteoporosis, but they are not automatically absorbed in the gastrointestinal tract. Nanotechnology is presumed to have a capacity in resolving this problem. The preparation and characterization of calcium carbonate nano particle to improve the solubility was performed. Calcium carbonate nano particles were synthesized using precipitation method from cockle shells (Anadara granosa Linn). Samples of the cockle shells were dried in an oven at temperature of 50°C for 7 (seven) days and subsequently they were crushed and blended into fine powder that was sieved through 125-μm sieve. The synthesis of calcium carbonate nanocrystals was done by extracting using hydro chloride acid and various concentrations of sodium hydroxide were used to precipitate the calcium carbonate nano particles. The size of the nano particles was determined by SEM, XRD data, and Fourier transform infrared spectroscopy (FT-IR). The results of XRD indicated that the overall crystalline structure and phase purity of the typical calcite phase CaCO3 particles were approximately 300 nm in size. The method to find potential applications in industry to yield the large scale synthesis of aragonite nano particles by a low cost but abundant natural resource such as cockle shells is required.

Role of nano and micron-sized inclusions on the oxygen controlled preform optimized infiltration growth processed YBCO superconductors

NASA Astrophysics Data System (ADS)

Pavan Kumar Naik, S.; Bai, V. Seshu

2017-02-01

In the present work, with the aim of improving the local flux pinning at the unit cell level in the YBa2Cu3O7-δ (YBCO) bulk superconductors, 20 wt% of nanoscale Sm2O3 and micron sized (Nd, Sm, Gd)2BaCuO5 secondary phase particles were added to YBCO and processed in oxygen controlled preform optimized infiltration growth process. Nano Dispersive Sol Casting method is employed to homogeneously distribute the nano Sm2O3 particles of 30-50 nm without any agglomeration in the precursor powder. Microstructural investigations on doped samples show the chemical fluctuations as annuli cores in the 211 phase particles. The introduction of mixed rare earth elements at Y-site resulted in compositional fluctuations in the superconducting matrix. The associated lattice mismatch defects have provided flux pinning up to large magnetic fields. Magnetic field dependence of current density (Jc(H)) at different temperatures revealed that the dominant pinning mechanism is caused by spatial variations of critical temperatures, due to the spatial fluctuations in the matrix composition. As the number of rare earth elements increased in the YBCO, the peak field position in the scaling of the normalized pinning force density (Fp/Fp max) significantly gets shifted towards the higher fields. The curves of Jc(H) and Fp/Fp max at different temperatures clearly indicate the LRE substitution for LRE' or Ba-sites for δTc pinning.

Nano-sized, quaternary titanium(IV) metal-organic frameworks with multidentate ligands.

PubMed

Baranwal, Balram Prasad; Singh, Alok Kumar

2010-12-01

Some mononuclear nano-sized, quaternary titanium(IV) complexes having the general formula [Ti(acac)(OOCR)2(SB)] (where Hacac=acetylacetone, R=C15H31 or C17H35, HSB=Schiff bases) have been synthesized using different multidentate ligands. These were characterized by elemental analyses, molecular weight determinations and spectral (FTIR, 1H NMR and powder XRD) studies. Conductance measurement indicated their non-conducting nature which may behave like insulators. Structural parameters like the values of limiting indices h, k, l, cell constants a, b, c, angles α, β, γ and particle size are calculated from powder XRD data for complex 1 which indicated nano-sized triclinic system in them. Bidentate chelating nature of acetylacetone, carboxylate and Schiff base anions in the complexes was established by their infrared spectra. Molecular weight determinations confirmed mononuclear nature of the complexes. On the basis of physico-chemical studies, coordination number 8 was assigned for titanium(IV) in the complexes. Transmission electron microscopy (TEM) and the selected area electron diffraction (SAED) studies indicated spherical particles with poor crystallinity. Copyright © 2010 Elsevier B.V. All rights reserved.

Al3+ ions dependent structural and magnetic properties of Co-Ni nano-alloys.

PubMed

Kadam, R H; Alone, Suresh T; Gaikwad, Anil S; Birajdar, A P; Shirsath, Sagar E

2014-06-01

Ferrite samples with a chemical formula Co0.5Ni0.5Al(x)Fe(2-x)O4 (where x = 0.0, 0.25, 0.5, 0.75 and 1.0) were synthesized by sol-gel auto-combustion method. The synthesized samples were annealed at 600 degrees C for 4 h. An analysis of X-ray diffraction (XRD) patterns reveals the formation of single phase cubic spinel structure. The lattice parameter decreased linearly with the increasing Al content x. Nano size of the powders were confirmed by the transmission electron micrographs (TEM). Particle size, bulk density decreased whereas specific surface area and porosity of the samples increased with the Al substitution. Cation distribution of constituent ions shows linear dependence of Al substitution. Based on the cation distribution obtained from XRD data, structural parameters such as lattice parameters, ionic radii of available sites and the oxygen parameter 'u' is calculated. Saturation magnetization (M(s)), magneton number (n(B)) and coercivity (H(c)) decreased with the Al substitution. Possible explanation for the observed structural and magnetic behavior with various Al content are discussed.

Size-Dependent Mechanism of Intracellular Localization and Cytotoxicity of Mono-Disperse Spherical Mesoporous Nano- and Micron-Bioactive Glass Particles

PubMed Central

Li, Yuli; Hu, Qing; Miao, Guohou; Zhang, Qing; Yuan, Bo; Zhu, Ye; Fu, Xiaoling; Chen, Xiaofeng; Mao, Chuanbin

2016-01-01

Mono-disperse spherical mesoporous nano- and micro- bioactive glass particles (NMBGs) can find potential use in bone tissue engineering. However, their size-dependent interaction with osteoblasts has never been studied. Herein, the proliferation, morphology, cytoskeleton organization and apoptosis of MC3T3-E1 osteoblasts are studied in response to the NMBGs with varying sizes (from 61 to 1085 nm) at different concentrations. Generally, smaller NMBGs at a lower dose show weaker cytotoxicity compared to the larger particles and higher doses, arising from a novel size-dependent mechanism of intracellular localization of NMBGs observed by electron and confocal microscopy. Specifically, NMBGs pass through perinuclear membrane of the cells to initiate endocytosis. Once internalized, the sizes of NMBGs are found to play a significant role in determining their intracellular localization. When the NMBGs are smaller than 174 nm, they are transported via the lysosomal pathway and phagocytized in lysosomes, resulting in little cytotoxicity at later time points. On the contrary, larger NMBGs (over 174 nm) escape from the lysosomes after endocytosis, and are localized inside the intra-cytoplasmic vacuoles or randomly in the cytoplasm of cells. Their lysosomal escape may damage the lysosomes, inducing cell apoptosis and thus the greater cytotoxicity. PMID:27305811

Differential effect of hydroxyapatite nano-particle versus nano-rod decorated titanium micro-surface on osseointegration.

PubMed

Bai, Long; Liu, Yanlian; Du, Zhibin; Weng, Zeming; Yao, Wei; Zhang, Xiangyu; Huang, Xiaobo; Yao, Xiaohong; Crawford, Ross; Hang, Ruiqiang; Huang, Di; Tang, Bin; Xiao, Yin

2018-06-15

Coating materials applied for intraosseous implants must be optimized to stimulate osseointegration. Osseointegration is a temporal and spatial physiological process that not only requires interactions between osteogenesis and angiogenesis but also necessitates a favorable immune microenvironment. It is now well-documented that hierarchical nano-micro surface structures promote the long-term stability of implants, the interactions between nano-micro structure and the immune response are largely unknown. Here, we report the effects of microporous titanium (Ti) surfaces coated with nano-hydroxyapatite (HA) produced by micro-arc oxidation and steam-hydrothermal treatment (SHT) on multiple cell behavior and osseointegration. By altering the processing time of SHT it was possible to shift HA structures from nano-particles to nano-rods on the microporous Ti surfaces. Ti surfaces coated with HA nano-particles were found to modulate the inflammatory response resulting in an osteoimmune microenvironment more favorable for osteo-/angio-genesis, most likely via the activation of certain key signaling pathways (TGF-β, OPG/RANKL, and VEGF). By contrast, Ti surfaces coated with nano-rod shaped HA particles had a negative impact on osteo-/angio-genesis and osteoimmunomodulation. In vivo results further demonstrated that Ti implant surfaces decorated with HA nano-particles can stimulate new bone formation and osseointegration with enhanced interaction between osteocytes and implant surfaces. This study demonstrated that Ti implants with micro-surfaces coated with nano-particle shaped HA have a positive impact on osseointegration. Osteo-/angio-genesis are of importance during osteointegration of the implants. Recent advances unravel that immune response of macrophages and its manipulated osteoimmunomodulation also exerts a pivotal role to determine the fate of the implant. Surface nano-micro modification has evidenced to be efficient to influence osteogenesis, however, little is

Preparation of uniform-sized multiple emulsions and micro/nano particulates for drug delivery by membrane emulsification.

PubMed

Liu, Wei; Yang, Xiang-Liang; Ho, W S Winston

2011-01-01

Much attention has in recent years been paid to fine applications of drug delivery systems, such as multiple emulsions, micro/nano solid lipid and polymer particles (spheres or capsules). Precise control of particle size and size distribution is especially important in such fine applications. Membrane emulsification can be used to prepare uniform-sized multiple emulsions and micro/nano particulates for drug delivery. It is a promising technique because of the better control of size and size distribution, the mildness of the process, the low energy consumption, easy operation and simple equipment, and amendable for large scale production. This review describes the state of the art of membrane emulsification in the preparation of monodisperse multiple emulsions and micro/nano particulates for drug delivery in recent years. The principles, influence of process parameters, advantages and disadvantages, and applications in preparing different types of drug delivery systems are reviewed. It can be concluded that the membrane emulsification technique in preparing emulsion/particulate products for drug delivery will further expand in the near future in conjunction with more basic investigations on this technique. Copyright © 2010 Wiley-Liss, Inc. and the American Pharmacists Association

Size dependent compressibility of nano-ceria: Minimum near 33 nm

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

Rodenbough, Philip P.; Chemistry Department, Columbia University, New York, New York 10027; Song, Junhua

2015-04-20

We report the crystallite-size-dependency of the compressibility of nanoceria under hydrostatic pressure for a wide variety of crystallite diameters and comment on the size-based trends indicating an extremum near 33 nm. Uniform nano-crystals of ceria were synthesized by basic precipitation from cerium (III) nitrate. Size-control was achieved by adjusting mixing time and, for larger particles, a subsequent annealing temperature. The nano-crystals were characterized by transmission electron microscopy and standard ambient x-ray diffraction (XRD). Compressibility, or its reciprocal, bulk modulus, was measured with high-pressure XRD at LBL-ALS, using helium, neon, or argon as the pressure-transmitting medium for all samples. As crystallite sizemore » decreased below 100 nm, the bulk modulus first increased, and then decreased, achieving a maximum near a crystallite diameter of 33 nm. We review earlier work and examine several possible explanations for the peaking of bulk modulus at an intermediate crystallite size.« less

NanoRocks: A Long-Term Microgravity Experiment to Stydy Planet Formation and Planetary Ring Particles

NASA Astrophysics Data System (ADS)

Brisset, J.; Colwell, J. E.; Dove, A.; Maukonen, D.; Brown, N.; Lai, K.; Hoover, B.

2015-12-01

We report on the results of the NanoRocks experiment on the International Space Station (ISS), which simulates collisions that occur in protoplanetary disks and planetary ring systems. A critical stage of the process of early planet formation is the growth of solid bodies from mm-sized chondrules and aggregates to km-sized planetesimals. To characterize the collision behavior of dust in protoplanetary conditions, experimental data is required, working hand in hand with models and numerical simulations. In addition, the collisional evolution of planetary rings takes place in the same collisional regime. The objective of the NanoRocks experiment is to study low-energy collisions of mm-sized particles of different shapes and materials. An aluminum tray (~8x8x2cm) divided into eight sample cells holding different types of particles gets shaken every 60 s providing particles with initial velocities of a few cm/s. In September 2014, NanoRocks reached ISS and 220 video files, each covering one shaking cycle, have already been downloaded from Station. The data analysis is focused on the dynamical evolution of the multi-particle systems and on the formation of cluster. We track the particles down to mean relative velocities less than 1 mm/s where we observe cluster formation. The mean velocity evolution after each shaking event allows for a determination of the mean coefficient of restitution for each particle set. These values can be used as input into protoplanetary disk and planetary rings simulations. In addition, the cluster analysis allows for a determination of the mean final cluster size and the average particle velocity of clustering onset. The size and shape of these particle clumps is crucial to understand the first stages of planet formation inside protoplanetary disks as well as many a feature of Saturn's rings. We report on the results from the ensemble of these collision experiments and discuss applications to planetesimal formation and planetary ring

Nano-particle modified stationary phases for high-performance liquid chromatography.

PubMed

Nesterenko, Ekaterina P; Nesterenko, Pavel N; Connolly, Damian; He, Xiaoyun; Floris, Patrick; Duffy, Emer; Paull, Brett

2013-08-07

This review covers the latest developments and applications of nano-materials in stationary phase development for various modes of high-performance liquid chromatography. Specific attention is placed upon the development of new composite phases, including the synthetic and immobilisation strategies used, to produce either encapsulated nano-particles, or surface attached nano-particles, layers, coatings and other structures. The resultant chromatographic applications, where applicable, are discussed with comment upon enhanced selectivity and/or efficiency of the nano-particle modified phases, where such effects have been identified. In the main this review covers developments over the past five years and is structured according to the nature of the nano-particles themselves, including carbonaceous, metallic, inorganic, and organopolymer based materials.

Effect of synthesis methods with different annealing temperatures on micro structure, cations distribution and magnetic properties of nano-nickel ferrite

NASA Astrophysics Data System (ADS)

El-Sayed, Karimat; Mohamed, Mohamed Bakr; Hamdy, Sh.; Ata-Allah, S. S.

2017-02-01

Nano-crystalline NiFe2O4 was synthesized by citrate and sol-gel methods at different annealing temperatures and the results were compared with a bulk sample prepared by ceramic method. The effect of methods of preparation and different annealing temperatures on the crystallize size, strain, bond lengths, bond angles, cations distribution and degree of inversions were investigated by X-ray powder diffraction, high resolution transmission electron microscope, Mössbauer effect spectrometer and vibrating sample magnetometer. The cations distributions were determined at both octahedral and tetrahedral sites using both Mössbauer effect spectroscopy and a modified Bertaut method using Rietveld method. The Mössbauer effect spectra showed a regular decrease in the hyperfine field with decreasing particle size. Saturation magnetization and coercivity are found to be affected by the particle size and the cations distribution.

Sintered magnetic cores of high Bs Fe84.3Si4B8P3Cu0.7 nano-crystalline alloy with a lamellar microstructure

NASA Astrophysics Data System (ADS)

Zhang, Yan; Sharma, Parmanand; Makino, Akihiro

2014-05-01

Fabrication of bulk cores of nano-crystalline Fe84.3Si4B8P3Cu0.7 alloy with a lamellar type of microstructure is reported. Amorphous ribbon flakes of size ˜1.0-2.0 mm were compacted in the bulk form by spark plasma sintering technique at different sintering temperatures. High density (˜96.4%) cores with a uniform nano-granular structure made from α-Fe (˜31 nm) were obtained. These cores show excellent mechanical and soft magnetic properties. The lamellar micro-structure is shown to be important in achieving significantly lower magnetic core loss than the non-oriented silicon steel sheets, commercial powder cores and even the core made of the same alloy with finer and randomly oriented powder particles.

Preparation of magnetic TNT-imprinted polymer nanoparticles and their accumulation onto magnetic carbon paste electrode for TNT determination.

PubMed

Alizadeh, Taher

2014-11-15

In this study, the TNT-imprinted polymer shell was created on nano-sized Fe3O4 cores in order to construct the nano-sized magnetic molecularly imprinted polymer (nano-MMIP). For this purpose, the surface of the synthesized magnetic nanoparticles was modified with methacrylic acid. The modified particles were then utilized as the core on which the TNT-imprinted polymeric shell was synthesized. The synthesized materials were then characterized by scanning electron microscopy, FT-IR and thermal gravimetric analysis (TGA). The resulting nano-MMIP particles were suspended in TNT solution and then collected on the surface of a carbon paste electrode via a permanent magnet, situated within the CP electrode. The extracted TNT was analyzed on the CP electrode by applying square wave voltammetry (SWV). It was found that the oxidative signal of TNT is much favorable for TNT detection on the resulting magnetic carbon paste electrode. The electrode with nano-MMIP showed distinctly higher signal to TNT, compared to that containing magnetic non-imprinted polymer (MNIP) nanoparticles. All parameters influencing the method performance including extraction pH, extraction time and sorbent amount were evaluated and optimized. The developed method showed a dynamic linear concentration range of 1.0-130.0 nM for TNT measurement. The detection limit of the method was calculated to be 0.5 nM. The method showed appropriate capability for TNT analysis in real water samples. Copyright © 2014. Published by Elsevier B.V.

Nano-size metallic oxide particle synthesis in Fe-Cr alloys by ion implantation

NASA Astrophysics Data System (ADS)

Zheng, C.; Gentils, A.; Ribis, J.; Borodin, V. A.; Delauche, L.; Arnal, B.

2017-10-01

Oxide Dispersion Strengthened (ODS) steels reinforced with metal oxide nanoparticles are advanced structural materials for nuclear and thermonuclear reactors. The understanding of the mechanisms involved in the precipitation of nano-oxides can help in improving mechanical properties of ODS steels, with a strong impact for their commercialization. A perfect tool to study these mechanisms is ion implantation, where various precipitate synthesis parameters are under control. In the framework of this approach, high-purity Fe-10Cr alloy samples were consecutively implanted with Al and O ions at room temperature and demonstrated a number of unexpected features. For example, oxide particles of a few nm in diameter could be identified in the samples already after ion implantation at room temperature. This is very unusual for ion beam synthesis, which commonly requires post-implantation high-temperature annealing to launch precipitation. The observed particles were composed of aluminium and oxygen, but additionally contained one of the matrix elements (chromium). The crystal structure of aluminium oxide compound corresponds to non-equilibrium cubic γ-Al2O3 phase rather than to more common corundum. The obtained experimental results together with the existing literature data give insight into the physical mechanisms involved in the precipitation of nano-oxides in ODS alloys.

Chitosan-coated doxorubicin nano-particles drug delivery system inhibits cell growth of liver cancer via p53/PRC1 pathway.

PubMed

Ye, Bai-Liang; Zheng, Ru; Ruan, Xiao-Jiao; Zheng, Zhi-Hai; Cai, Hua-Jie

2018-01-01

Nano-particles have been widely used in target-specific drug delivery system and showed advantages in cancers treatment. This study aims to evaluate the effect of chitosan coated doxorubicin nano-particles drug delivery system in liver cancer. The chitosan nano-particles were prepared by using the ionic gelation method. The characterizations of the nano-particles were determined by transmission electron microscopy. The cytotoxicity was detected by MTT assay, and the endocytosis, cell apoptosis and cell cycle were examined by flow cytometry. The protein level was analyzed with western blot. The dual luciferase reporter assay was performed to assess the interaction between p53 and the promoter of PRC1, and chromatin immune-precipitation was used to verify the binding between them. The FA-CS-DOX nano-particles were irregular and spherical particles around 30-40 nm, with uniform size and no adhesion. No significant difference was noted in doxorubicin release rate between CS-DOX and FA-CS-DOX. FA-CS-DOX nano-particles showed stronger cytotoxicity than CS-DOX. FA-CS-DOX nano-particles promoted the apoptosis and arrested cell cycle at G2/M phase, and they up-regulated p53. FA-CS-DOX nano-particles inhibited cell survival through p53/PRC1 pathway. Chitosan-coated doxorubicin nano-particles drug delivery system inhibits cell growth of liver cancer by promoting apoptosis and arresting cell cycle at G2/M phase through p53/PRC1 pathway. Copyright © 2017 Elsevier Inc. All rights reserved.

Alignment of SWNTs by protein-ligand interaction of functionalized magnetic particles under low magnetic fields.

PubMed

Park, Tae Jung; Park, Jong Pil; Lee, Seok Jae; Jung, Dae-Hwan; Ko, Young Koan; Jung, Hee-Tae; Lee, Sang Yup

2011-05-01

Carbon nanotubes (CNTs) have attracted considerable attention for applications using their superior mechanical, thermal and electrical properties. A simple method to controllably align single-walled CNTs (SWNTs) by using magnetic particles embedded with superparamagnetic iron oxide as an accelerator under the magnetic field was developed. The functionalization of SWNTs using biotin, interacted with streptavidin-coupled magnetic particles (micro-to-nano in diameter), and layer-by-layer assembly were performed for the alignment of a particular direction onto the clean silicon and the gold substrate at very low magnetic forces (0.02-0.89 T) at room temperature. The successful alignment of the SWNTs with multi-layer film was observed by scanning electron microscopy (SEM) and transmission electron microscopy (TEM). By changing the orientation and location of the substrates, crossed-networks of SWNTs-magnetic particle complex could easily be fabricated. We suggest that this approach, which consists of a combination of biological interaction among streptavidin-biotin and magnetite particles, should be useful for lateral orientation of individual SWNTs with controllable direction.

Toxicogenomic analysis of the particle dose- and size-response relationship of silica particles-induced toxicity in mice

NASA Astrophysics Data System (ADS)

Lu, Xiaoyan; Jin, Tingting; Jin, Yachao; Wu, Leihong; Hu, Bin; Tian, Yu; Fan, Xiaohui

2013-01-01

This study investigated the relationship between particle size and toxicity of silica particles (SP) with diameters of 30, 70, and 300 nm, which is essential to the safe design and application of SP. Data obtained from histopathological examinations suggested that SP of these sizes can all induce acute inflammation in the liver. In vivo imaging showed that intravenously administrated SP are mainly present in the liver, spleen and intestinal tract. Interestingly, in gene expression analysis, the cellular response pathways activated in the liver are predominantly conserved independently of particle dose when the same size SP are administered or are conserved independently of particle size, surface area and particle number when nano- or submicro-sized SP are administered at their toxic doses. Meanwhile, integrated analysis of transcriptomics, previous metabonomics and conventional toxicological results support the view that SP can result in inflammatory and oxidative stress, generate mitochondrial dysfunction, and eventually cause hepatocyte necrosis by neutrophil-mediated liver injury.

Investigation of the capture of magnetic particles from high-viscosity fluids using permanent magnets

PubMed Central

Garraud, A.; Velez, C.; Shah, Y.; Garraud, N.; Kozissnik, B.; Yarmola, E. G.; Allen, K. D.; Dobson, J.; Arnold, D. P.

2015-01-01

Goal This paper investigates the practicality of using a small, permanent magnet to capture magnetic particles out of high-viscosity biological fluids, such as synovial fluid. Methods Numerical simulations are used to predict the trajectory of magnetic particles toward the permanent magnet. The simulations are used to determine a “collection volume” with a time-dependent size and shape, which determines the number of particles that can be captured from the fluid in a given amount of time. Results The viscosity of the fluid strongly influences the velocity of the magnetic particles towards the magnet, hence the collection volume after a given time. In regards to the design of the magnet, the overall size is shown to most strongly influence the collection volume in comparison to the magnet shape or aspect ratio. Conclusion Numerical results showed good agreement with in vitro experimental magnetic collection results. Significance In the long-term, this work aims to facilitate optimization of the collection of magnetic particle-biomarker conjugates from high-viscosity biological fluids without the need to remove the fluid from a patient. PMID:26208261

Investigation of the Capture of Magnetic Particles From High-Viscosity Fluids Using Permanent Magnets.

PubMed

Garraud, Alexandra; Velez, Camilo; Shah, Yash; Garraud, Nicolas; Kozissnik, Bettina; Yarmola, Elena G; Allen, Kyle D; Dobson, Jon; Arnold, David P

2016-02-01

This paper investigates the practicality of using a small, permanent magnet to capture magnetic particles out of high-viscosity biological fluids, such as synovial fluid. Numerical simulations are used to predict the trajectory of magnetic particles toward the permanent magnet. The simulations are used to determine a "collection volume" with a time-dependent size and shape, which determines the number of particles that can be captured from the fluid in a given amount of time. The viscosity of the fluid strongly influences the velocity of the magnetic particles toward the magnet, hence, the collection volume after a given time. In regards to the design of the magnet, the overall size is shown to most strongly influence the collection volume in comparison to the magnet shape or aspect ratio. Numerical results showed good agreement with in vitro experimental magnetic collection results. In the long term, this paper aims to facilitate optimization of the collection of magnetic particle-biomarker conjugates from high-viscosity biological fluids without the need to remove the fluid from a patient.

Clinically viable magnetic poly(lactide-co-glycolide) (PLGA) particles for MRI-based cell tracking

PubMed Central

Granot, Dorit; Nkansah, Michael K.; Bennewitz, Margaret F.; Tang, Kevin S.; Markakis, Eleni A.; Shapiro, Erik M.

2013-01-01

Purpose To design, fabricate, characterize and in vivo assay clinically viable magnetic particles for MRI-based cell tracking. Methods PLGA encapsulated magnetic nano- and microparticles were fabricated. Multiple biologically relevant experiments were performed to assess cell viability, cellular performance and stem cell differentiation. In vivo MRI experiments were performed to separately test cell transplantation and cell migration paradigms, as well as in vivo biodegradation. Results Highly magnetic nano- (~100 nm) and microparticles (~1–2 μm) were fabricated. Magnetic cell labeling in culture occurred rapidly achieving 3–50 pg Fe/cell at 3 hrs for different particles types, and >100 pg Fe/cell after 10 hours, without the requirement of a transfection agent, and with no effect on cell viability. The capability of magnetically labeled mesenchymal or neural stem cells to differentiate down multiple lineages, or for magnetically labeled immune cells to release cytokines following stimulation, was uncompromised. An in vivo biodegradation study revealed that NPs degraded ~80% over the course of 12 weeks. MRI detected as few as 10 magnetically labeled cells, transplanted into the brains of rats. Also, these particles enabled the in vivo monitoring of endogenous neural progenitor cell migration in rat brains over 2 weeks. Conclusion The robust MRI properties and benign safety profile of these particles make them promising candidates for clinical translation for MRI-based cell tracking. PMID:23568825

Sunscreens with Titanium Dioxide (TiO2) Nano-Particles: A Societal Experiment

PubMed Central

van de Poel, Ibo; Osseweijer, Patricia

2010-01-01

The risks of novel technologies, such as nano(bio)technology cannot be fully assessed due to the existing uncertainties surrounding their introduction into society. Consequently, the introduction of innovative technologies can be conceptualised as a societal experiment, which is a helpful approach to evaluate moral acceptability. This approach is illustrated with the marketing of sunscreens containing nano-sized titanium dioxide (TiO2) particles. We argue that the marketing of this TiO2 nanomaterial in UV protective cosmetics is ethically undesirable, since it violates four reasonable moral conditions for societal experimentation (absence of alternatives, controllability, limited informed consent, and continuing evaluation). To remedy the current way nano-sized TiO2 containing sunscreens are utilised, we suggest five complementing actions (closing the gap, setup monitoring tools, continuing review, designing for safety, and regulative improvements) so that its marketing can become more acceptable. PMID:20835397

Synthesis and characterization of magnetically hard Fe-Pt alloy nanoparticles and nano-islands

NASA Astrophysics Data System (ADS)

Hu, Xiaocao

In this dissertation, we explored the fabrication of FePt nanoparticles and nano-islands with the face-centered tetragonal (fct, L10) phase prepared by both chemical synthesis routes and physical vapor deposition. Microstructure and magnetic properties characterizations were used to gain a fundamental understanding of the nano-structure formation and atomic ordering behavior and determine the possible applications in the next generation ultra-high density magnetic storage media. FePt nanoparticles prepared by thermal decomposition of iron pentacarbonyl [Fe(CO)5] have been widely investigated and by tuning the processing procedure monodispersed FePt nanoparticles with good assembly can be obtained. The as-made FePt nanoparticles are usually in the magnetically soft face-centered cubic (fcc) phase. To transformation to the fct phase, post-annealing at above 600°C is needed which, however, introduces undesirable agglomeration and sintering. To address this problem, we used three different fabrication processes which are discussed below. In the first fabrication experiment, the FePt nanoparticles were fabricated by a novel environmental friendly method involving crystalline saline complex hexaaquairon (II) hexachloroplatinate ([Fe(H2O)6]PtCl 6) with a special layered structure. Then the precursor was ball milled with NaCl and annealed at temperatures above 400°C under a reducing atmosphere of forming gas (95% Ar and 5% H2) FePt nanoparticles were obtained after washing away NaCl with deionized water. This method avoids the use of the very poisonous Fe(CO)5 and other organic solvents such as oleylamine and oleic acid. Instead, environmentally friendly NaCl and water were used. The size of FePt nanoparticles was controlled by varying the proportion of precursor and NaCl (from 10mg/20g to 50mg/20g). Particles with size in the range of 6.2--13.2 nm were obtained. All the nanoparticles annealed above 400°C are in the highly ordered fct phase with a coercivity range of 4

Interaction of micron and nano-sized particles with cells of the dura mater.

PubMed

Papageorgiou, Iraklis; Marsh, Rainy; Tipper, Joanne L; Hall, Richard M; Fisher, John; Ingham, Eileen

2014-10-01

Intervertebral total disc replacements (TDR) are used in the treatment of degenerative spinal disc disease. There are, however, concerns that they may be subject to long-term failure due to wear. The adverse effects of TDR wear have the potential to manifest in the dura mater and surrounding tissues. The aim of this study was to investigate the physiological structure of the dura mater, isolate the resident dural epithelial and stromal cells and analyse the capacity of these cells to internalise model polymer particles. The porcine dura mater was a collagen-rich structure encompassing regularly arranged fibroblastic cells within an outermost epithelial cell layer. The isolated dural epithelial cells had endothelial cell characteristics (positive for von Willebrand factor, CD31, E-cadherin and desmoplakin) and barrier functionality whereas the fibroblastic cells were positive for collagen I and III, tenascin and actin. The capacity of the dural cells to take up model particles was dependent on particle size. Nanometer sized particles readily penetrated both types of cells. However, dural fibroblasts engulfed micron-sized particles at a much higher rate than dural epithelial cells. The study suggested that dural epithelial cells may offer some barrier to the penetration of micron-sized particles but not nanometer sized particles. © 2014 The Authors. Journal of Biomedical Materials Research Part B: Applied Biomaterials Published by Wiley Periodicals, Inc.

Perfluorocarbon Particle Size Influences Magnetic Resonance Signal and Immunological Properties of Dendritic Cells

PubMed Central

Waiczies, Helmar; Lepore, Stefano; Janitzek, Nicole; Hagen, Ulrike; Seifert, Frank; Ittermann, Bernd; Purfürst, Bettina; Pezzutto, Antonio; Paul, Friedemann; Niendorf, Thoralf; Waiczies, Sonia

2011-01-01

The development of cellular tracking by fluorine (19F) magnetic resonance imaging (MRI) has introduced a number of advantages for following immune cell therapies in vivo. These include improved signal selectivity and a possibility to correlate cells labeled with fluorine-rich particles with conventional anatomic proton (1H) imaging. While the optimization of the cellular labeling method is clearly important, the impact of labeling on cellular dynamics should be kept in mind. We show by 19F MR spectroscopy (MRS) that the efficiency in labeling cells of the murine immune system (dendritic cells) by perfluoro-15-crown-5-ether (PFCE) particles increases with increasing particle size (560>365>245>130 nm). Dendritic cells (DC) are professional antigen presenting cells and with respect to impact of PFCE particles on DC function, we observed that markers of maturation for these cells (CD80, CD86) were also significantly elevated following labeling with larger PFCE particles (560 nm). When labeled with these larger particles that also gave an optimal signal in MRS, DC presented whole antigen more robustly to CD8+ T cells than control cells. Our data suggest that increasing particle size is one important feature for optimizing cell labeling by PFCE particles, but may also present possible pitfalls such as alteration of the immunological status of these cells. Therefore depending on the clinical scenario in which the 19F-labeled cellular vaccines will be applied (cancer, autoimmune disease, transplantation), it will be interesting to monitor the fate of these cells in vivo in the relevant preclinical mouse models. PMID:21811551

PREFACE: 8th International Conference on Fine Particle Magnetism (ICFPM2013)

NASA Astrophysics Data System (ADS)

2014-06-01

. Nanomagnetism has provided physicists with a rich and challenging playground for the generalization and application of the concepts and techniques of statistical mechanics at equilibrium and out of equilibrium. In particular, the great efforts devoted to the investigation of nanomagnetism have been rewarded by a noticeable progress in shedding light on our understanding of the finite-size and surface effects on the static and dynamic properties of nano-scaled magnetic systems. Today, active investigation of the fundamental properties of magnetic nanoparticles and the novelties they exhibit, continues with the development of new materials using a variety of modern chemical and physical techniques. Likewise, the characterization and measurements of their properties are becoming more precise than ever thanks to a large choice of cutting-edge new techniques with ever increasing temporal and spatial resolution. This opens up, once again, new perspectives for a better control of the properties of single particles and their more efficient assemblage into more complex structures with ever more promising day-to-day applications such as magnetic recording, magneto-plasmonics, magneto-optics, magneto-calorics, micro- and nano-electronics, magnetic catalysis, and bio-nanomaterials. Hamid Kachkachi Chair of the 8th International Conference on Fine Particle Magnetism (ICFPM)

Size-uniform 200 nm particles: fabrication and application to magnetofection.

PubMed

Mair, Lamar; Ford, Kris; Alam, M d Rowshon; Kole, Ryszard; Fisher, Michael; Superfine, Richard

2009-04-01

We report on the fabrication of arrays of mono- and multimetallic particles via metal evaporation onto lithographically patterned posts, as well as the magnetic force calibration and successful magnetofection of iron particles grown via this method. This work represents the first instance in which metal evaporation onto post structures was used for the formation of released, shape-defined metal particles. Also, our work represents the first use of lithographically defined particles as agents of magnetofection. Using these techniques it is possible to create particles with complex shapes and lateral dimensions as small as 40 nm. Our demonstrated compositionally flexible particles are highly size-uniform due to their photolithographically defined growth substrates, with particle dimensions along two axes fixed at 200 nm; the third axis dimension can be varied from 20 nm to 300 nm during the deposition procedure. Atomic percent of metals incorporated into the particle volume is highly tunable and particles have been synthesized with as many as four different metals. We performed magnetic force calibrations on a single particle size for iron particles using an axially magnetized NeFeB permanent magnet and comparisons are made with commercially available magnetic beads. In order to evalutate their usefulness as magnetofection agents, an antisense oligonucleotide (ODN) designed to correct the aberrant splicing of enhanced green fluorescent protein mRNA, was successfully transfected into a modified HeLa cell line. Magnetically enhanced gene delivery was accomplished in vitro using antisense ODN-laden iron particles followed by application of a field gradient. Magnetically enhanced transfection resulted in a 76% and 139% increase in fluorescence intensity when compared to Lipofectamine and antisense ODN-loaded particles delivered without magnetic treatment, respectively. To our knowledge, these experiments constitute the first use of lithographically defined particles as

Size-Uniform 200 nm Particles: Fabrication and Application to Magnetofection

PubMed Central

Mair, Lamar; Ford, Kris; Alam, Rowshon; Kole, Ryszard; Fisher, Michael; Superfine, Richard

2009-01-01

We report on the fabrication of arrays of mono- and multimetallic particles via metal evaporation onto lithographically patterned posts, as well as the magnetic force calibration and successful magnetofection of iron particles grown via this method. This work represents the first instance in which metal evaporation onto post structures was used for the formation of released, shape-defined metal particles. Also, our work represents the first use of lithographically defined particles as agents of magnetofection. Using these techniques it is possible to create particles with complex shapes and lateral dimensions as small as 40 nm. Our demonstrated compositionally flexible particles are highly size-uniform due to their photolithographically defined growth substrates, with particle dimensions along two axes fixed at 200 nm; the third axis dimension can be varied from 20 nm to 300 nm during the deposition procedure. Atomic percent of metals incorporated into the particle volume is highly tunable and particles have been synthesized with as many as four different metals. We performed magnetic force calibrations on a single particle size for iron particles using an axially magnetized NeFeB permanent magnet and comparisons are made with commercially available magnetic beads. In order to evalutate their usefulness as magnetofection agents, an antisense oligonucleotide (ODN) designed to correct the aberrant splicing of enhanced green fluorescent protein mRNA, was successfully transfected into a modified HeLa cell line. Magnetically enhanced gene delivery was accomplished in vitro using antisense ODN-laden iron particles followed by application of a field gradient. Magnetically enhanced transfection resulted in a 76% and 139% increase in fluorescence intensity when compared to Lipofectamine and antisense ODN-loaded particles delivered without magnetic treatment, respectively. To our knowledge, these experiments constitute the first use of lithographically defined particles as

Magnetic manipulation of particles and cells in ferrofluid flow through straight microchannels using two magnets

NASA Astrophysics Data System (ADS)

Zeng, Jian

Microfluidic devices have been increasingly used in the past two decades for particle and cell manipulations in many chemical and biomedical applications. A variety of force fields have been demonstrated to control particle and cell transport in these devices including electric, magnetic, acoustic, and optical forces etc. Among these particle handling techniques, the magnetic approach provides clear advantages over others such as low cost, noninvasive, and free of fluid heating issues. However, the current knowledge of magnetic control of particle transport is still very limited, especially lacking is the handling of diamagnetic particle. This thesis is focused on the magnetic manipulation of diamagnetic particles and cells in ferrofluid flow through the use of a pair of permanent magnets. By varying the configuration of the two magnets, diverse operations of particles and cells is implemented in a straight microchannel that can potentially be integrated into lab-on-a-chip devices for various applications. First, an approach for embedding two, symmetrically positioned, repulsive permanent magnets about a straight rectangular microchannel in a PDMS-based microfluidic device is developed for particle focusing. Focusing particles and cells into a tight stream is often required in order for continuous detection, counting, and sorting. The closest distance between the magnets is limited only by the size of the magnets involved in the fabrication process. The device is used to implement and investigate the three-dimensional magnetic focusing of polystyrene particles in ferrofluid microflow with both top-view and side-view visualizations. The effects of flow speed and particle size on the particle focusing effectiveness are studied. This device is also applied to magnetically focus yeast cells in ferrofluid, which proves to be biocompatible as verified by cell viability test. In addition, an analytical model is developed and found to be able to predict the experimentally

Synthesis and characterization of magnetic poly(divinyl benzene)/Fe3O4, C/Fe3O4/Fe, and C/Fe onionlike fullerene micrometer-sized particles with a narrow size distribution.

PubMed

Snovski, Ron; Grinblat, Judith; Margel, Shlomo

2011-09-06

Magnetic poly(divinyl benzene)/Fe(3)O(4) microspheres with a narrow size distribution were produced by entrapping the iron pentacarbonyl precursor within the pores of uniform porous poly(divinyl benzene) microspheres prepared in our laboratory, followed by the decomposition in a sealed cell of the entrapped Fe(CO)(5) particles at 300 °C under an inert atmosphere. Magnetic onionlike fullerene microspheres with a narrow size distribution were produced by annealing the obtained PDVB/Fe(3)O(4) particles at 500, 600, 800, and 1100 °C, respectively, under an inert atmosphere. The formation of carbon graphitic layers at low temperatures such as 500 °C is unique and probably obtained because of the presence of the magnetic iron nanoparticles. The annealing temperature allowed control of the composition, size, size distribution, crystallinity, porosity, and magnetic properties of the produced magnetic microspheres. © 2011 American Chemical Society

Magnetization reversal modes in fourfold Co nano-wire systems

NASA Astrophysics Data System (ADS)

Blachowicz, T.; Ehrmann, A.

2015-09-01

Magnetic nano-wire systems are, as well as other patterned magnetic structures, of special interest for novel applications, such as magnetic storage media. In these systems, the coupling between neighbouring magnetic units is most important for the magnetization reversal process of the complete system, leading to a variety of magnetization reversal mechanisms. This article examines the influence of the magnetic material on hysteresis loop shape, coercive field, and magnetization reversal modes. While iron nano-wire systems exhibit flat or one-step hysteresis loops, systems consisting of cobalt nano-wires show hysteresis loops with several longitudinal steps and transverse peaks, correlated to a rich spectrum of magnetization reversal mechanisms. We show that changing the material parameters while the system geometry stays identical can lead to completely different hysteresis loops and reversal modes. Thus, especially for finding magnetic nano-systems which can be used as quaternary or even higher-order storage devices, it is rational to test several materials for the planned systems. Apparently, new materials may lead to novel and unexpected behaviour - and can thus result in novel functionalities.

Nano-plastics in the aquatic environment.

PubMed

Mattsson, K; Hansson, L-A; Cedervall, T

2015-10-01

The amount of plastics released to the environment in modern days has increased substantially since the development of modern plastics in the early 1900s. As a result, concerns have been raised by the public about the impact of plastics on nature and on, specifically, aquatic wildlife. Lately, much attention has been paid to macro- and micro-sized plastics and their impact on aquatic organisms. However, micro-sized plastics degrade subsequently into nano-sizes whereas nano-sized particles may be released directly into nature. Such particles have a different impact on aquatic organisms than larger pieces of plastic due to their small size, high surface curvature, and large surface area. This review describes the possible sources of nano-sized plastic, its distribution and behavior in nature, the impact of nano-sized plastic on the well-being of aquatic organisms, and the difference of impact between nano- and micro-sized particles. We also identify research areas which urgently need more attention and suggest experimental methods to obtain useful data.

Biosensing Using Magnetic Particle Detection Techniques

PubMed Central

Chen, Yi-Ting; Kolhatkar, Arati G.; Zenasni, Oussama; Xu, Shoujun

2017-01-01

Magnetic particles are widely used as signal labels in a variety of biological sensing applications, such as molecular detection and related strategies that rely on ligand-receptor binding. In this review, we explore the fundamental concepts involved in designing magnetic particles for biosensing applications and the techniques used to detect them. First, we briefly describe the magnetic properties that are important for bio-sensing applications and highlight the associated key parameters (such as the starting materials, size, functionalization methods, and bio-conjugation strategies). Subsequently, we focus on magnetic sensing applications that utilize several types of magnetic detection techniques: spintronic sensors, nuclear magnetic resonance (NMR) sensors, superconducting quantum interference devices (SQUIDs), sensors based on the atomic magnetometer (AM), and others. From the studies reported, we note that the size of the MPs is one of the most important factors in choosing a sensing technique. PMID:28994727

Preparation and characterization of SiO2-coated submicron-sized L10 Fe-Pt particles

NASA Astrophysics Data System (ADS)

Hayashi, Yoshiaki; Ogawa, Tomoyuki; Ishiyama, Kazushi

2018-05-01

The development of magnets with higher performance is attracting increasing interest. The optimization of their microstructure is essential to enhance their properties, and a microstructure comprising magnetically isolated hard magnetic grains of a single-domain size has been proposed as an ideal structure for enhancing the coercivity of magnets. To obtain magnets with an ideal structure, we consider the fabrication of magnets by an approach based on core/shell nanoparticles with a hard magnetic core and a non-magnetic shell. In this study, to obtain particles for our proposed approach, we attempted to fabricate L10 Fe-Pt/SiO2-core/shell particles with submicron-sized cores less than the critical single-domain size. The fabrication of such core/shell particles was confirmed from morphology observations and XRD analysis of the particles. Although the formation of more desirable core/shell particles with submicron-sized single-crystal cores in the single-domain size range was not achieved, the fabricated core/shell particles showed a high coercivity of 25 kOe.

Effects of crystallite size on the structure and magnetism of ferrihydrite

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

Wang, Xiaoming; Zhu, Mengqiang; Koopal, Luuk K.

2015-12-15

The structure and magnetic properties of nano-sized (1.6 to 4.4 nm) ferrihydrite samples are systematically investigated through a combination of X-ray diffraction (XRD), X-ray pair distribution function (PDF), X-ray absorption spectroscopy (XAS) and magnetic analyses. The XRD, PDF and Fe K-edge XAS data of the ferrihydrite samples are all fitted well with the Michel ferrihydrite model, indicating similar local-, medium- and long-range ordered structures. PDF and XAS fitting results indicate that, with increasing crystallite size, the average coordination numbers of Fe–Fe and the unit cell parameter c increase, while Fe2 and Fe3 vacancies and the unit cell parameter a decrease.more » Mössbauer results indicate that the surface layer is relatively disordered, which might have been caused by the random distribution of Fe vacancies. These results support Hiemstra's surface-depletion model in terms of the location of disorder and the variations of Fe2 and Fe3 occupancies with size. Magnetic data indicate that the ferrihydrite samples show antiferromagnetism superimposed with a ferromagnetic-like moment at lower temperatures (100 K and 10 K), but ferrihydrite is paramagnetic at room temperature. In addition, both the magnetization and coercivity decrease with increasing ferrihydrite crystallite size due to strong surface effects in fine-grained ferrihydrites. Smaller ferrihydrite samples show less magnetic hyperfine splitting and a lower unblocking temperature (T B) than larger samples. The dependence of magnetic properties on grain size for nano-sized ferrihydrite provides a practical way to determine the crystallite size of ferrihydrite quantitatively in natural environments or artificial systems.« less

Synthesis of Ferrite Nickel Nano-particles and Its Role as a p-Dopant in the Improvement of Hole Injection of an Organic Light-Emitting Diode

NASA Astrophysics Data System (ADS)

Noori, Maryam; Jafari, Mohammad Reza; Hosseini, Sayed Mohsen; Shahedi, Zahra

2017-07-01

We fabricated an organometallic complex based on zinc ions using zinc complex as a fluorescent in organic light-emitting diodes (OLEDs). Also, the nano-particles of ferrite nickel were produced in a simple aqueous system prepared by mixing Ni (NO3)2, Fe (NO3)3 and deionized water solutions. The synthesized zinc bis (8-hydroxyquinoline) (Znq2) complex and NiFe2O4 nano-particles were characterized by using x-ray diffraction (XRD), ultraviolet-visible (UV-Vis), Fourier transform infrared spectroscopy (FT-IR) as well as photoluminescence spectroscopy analysis. Their energy level was also determined by some cyclic voltammetry (CV) measurements. The maximum green photoluminescence was observed at 565 nm. The nano-particles of ferrite nickel were utilized in preparation of OLEDs by blending of the magnetic nano-particles with PEDOT:PSS and Zn-complex solutions. The electrical and optical performance of prepared OLEDs with/without doped nano-particle was studied. The samples were configured into two structures: (1) Indium Tin Oxide (ITO)/ poly(3,4-ethylenedi-oxythiophene):poly(styrenesulfonate) (PEDOT:PSS)/Znq2/(2-4-biphenylyl)-5-phenyl-oxadiazole (PBD)/aluminum (Al) and (2) ITO/PEDOT:PSS:NiFe2O4(NPs)/Znq2/PBD/Al. Obtained results showed that the current density and electroluminescence efficiency were increased and the turn-on voltage decreased (about 3 V) by using nano-particles into a PEDOT:PSS layer (Hole transport layer). Also, the electroluminescence efficiency was decreased by incorporating magnetic nano-particles into a Zn-complex layer (emissive layer). It was found that utilizing NiFe2O4 nano-particles caused an increase of hole-injection layer conductivity effectively and a decrease of the turn-on voltage.

Characteristics of Sodium Polyacrylate/Nano-Sized Carbon Hydrogel for Biomedical Patch.

PubMed

Park, Jong-Kyu; Seo, Sun-Kyo; Cho, Seungkwan; Kim, Han-Sung; Lee, Chi-Hwan

2018-03-01

Conductive hydrogels were prepared for biomedical patch in order to improve the electrical conductivity. Sodium polyacrylate and nano-sized carbon were mixed and fabricated by aqueous solution gelation process in various contents of nano-sized carbon with 0.1, 0.5, 1.0 and 2.0 wt%. Sodium polyacrylate/nano-sized carbon conductive hydrogels were investigated by molecular structure, surface morphology and electrical conductivity. The conductivity of the hydrogel/nano-sized carbon conductive hydrogel proved to be 10% higher than conductive hydrogel without nano-sized carbon. However, it was founded that conductive hydrogels with nano-sized carbon content from 0.5 up to 2.0 wt% were remarkably decreased. This may be due to the non-uniform distribution of nano-sized carbon, resulting from agglomerates of nano-sized carbon. The developed hydrogel is intended for use in the medical and cosmetic fields that is applicable to supply micro-current from device to human body.

Microwave electromagnetic properties of carbonyl iron particles and Si/C/N nano-powder filled epoxy-silicone coating

NASA Astrophysics Data System (ADS)

Qing, Yuchang; Zhou, Wancheng; Luo, Fa; Zhu, Dongmei

2010-02-01

The electromagnetic characteristics of carbonyl iron particles and Si/C/N nano-powder filled epoxy-silicone coatings were studied. The reflection loss of the coatings exceeds -10 dB at 8-18 GHz and -9 dB at 2-18 GHz when the coating thickness is 1 and 3 mm, respectively. The dielectric and magnetic absorbers filled coatings possess excellent microwave absorption, which could be attributed to the proper incorporate of the multi-polarization mechanisms as well as strong natural resonance. It is feasible to develop the thin and wideband microwave absorbing coatings using carbonyl iron particles and Si/C/N nano-powder.

Impact of nano and bulk ZrO2, TiO2 particles on soil nutrient contents and PGPR.

PubMed

Karunakaran, Gopalu; Suriyaprabha, Rangaraj; Manivasakan, Palanisamy; Yuvakkumar, Rathinam; Rajendran, Venkatachalam; Kannan, Narayanasamy

2013-01-01

Currently, nanometal oxides are used extensively in different industries such as medicine, cosmetics and food. The increased consumption of nanoparticles (NPs) leads the necessity to understand the fate of the nanoparticles in the environment. The present study focused on the ecotoxicological behaviour of bulk and nano ZrO2 (Zirconia) and TiO2 (Titania) particles on PGPR (plant growth promoting rhizobacteria), soil and its nutrient contents. The microbial susceptibility study showed that nano TiO2 had 13 +/- 0.9 mm (B. megaterium), 15 +/- 0.2 mm (P. fluorescens), 16 +/- 0.2 mm (A. vinelandii) and 12 +/- 0.3 mm (B. brevis) zones of inhibition. However, nano and bulk ZrO2 particles were non-toxic to PGPR. In addition, it was found that toxicity varied depends on the medium of reaction. The soil study showed that nano TiO2 was found to be highly toxic, whereas bulk TiO2 was less toxic towards soil bacterial populations at 1000 mg L(-1). In contrast, nano and bulk ZrO2 were found to be inert at 1000 mg L(-1). The observed zeta potential and hydrophobicity of TiO2 particles causes more toxic than ZrO2 in parallel with particle size. However, nano TiO2 decreases the microbial population as well as nutrient level of the soil but not zirconia. Our finding shows that the mechanism of toxicity depends on size, hydrophobic potential and zeta potential of the metal oxide particles. Thus, it is necessary to take safety measures during the disposal and use of such toxic nanoparticles in the soil to prevent their hazardous effects.

Structural and Morphological Evaluation of Nano-Sized MoSi2 Powder Produced by Mechanical Milling

NASA Astrophysics Data System (ADS)

Sameezadeh, Mahmood; Farhangi, Hassan; Emamy, Masoud

Nano-sized intermetallic powders have received great attention owing to their property advantages over conventional micro-sized counterparts. In the present study nano-sized MoSi2 powder has been produced successfully from commercially available MoSi2 (3 μm) by a mechanical milling process carried out for a period of 100 hours. The effects of milling time on size and morphology of the powders were studied by SEM and TEM and image analyzing system. The results indicate that the as-received micrometric powder with a wide size distribution of irregular shaped morphology changes to a narrow size distribution of nearly equiaxed particles with the progress of attrition milling up to 100 h, reaching an average particle size of 71 nm. Structural evolution of milled samples was characterized by XRD to determine the crystallite size and lattice microstrain using Williamson-Hall method. According to the results, the crystallite size of the powders decreases continuously down to 23 nm with increasing milling time up to 100 h and this size refinement is more rapid at the early stages of the milling process. On the other hand, the lattice strain increases considerably with milling up to 65 h and further milling causes no significant changes of lattice strain.

Interaction of micron and nano-sized particles with cells of the dura mater

PubMed Central

Papageorgiou, Iraklis; Marsh, Rainy; Tipper, Joanne L; Hall, Richard M; Fisher, John; Ingham, Eileen

2014-01-01

Intervertebral total disc replacements (TDR) are used in the treatment of degenerative spinal disc disease. There are, however, concerns that they may be subject to long-term failure due to wear. The adverse effects of TDR wear have the potential to manifest in the dura mater and surrounding tissues. The aim of this study was to investigate the physiological structure of the dura mater, isolate the resident dural epithelial and stromal cells and analyse the capacity of these cells to internalise model polymer particles. The porcine dura mater was a collagen-rich structure encompassing regularly arranged fibroblastic cells within an outermost epithelial cell layer. The isolated dural epithelial cells had endothelial cell characteristics (positive for von Willebrand factor, CD31, E-cadherin and desmoplakin) and barrier functionality whereas the fibroblastic cells were positive for collagen I and III, tenascin and actin. The capacity of the dural cells to take up model particles was dependent on particle size. Nanometer sized particles readily penetrated both types of cells. However, dural fibroblasts engulfed micron-sized particles at a much higher rate than dural epithelial cells. The study suggested that dural epithelial cells may offer some barrier to the penetration of micron-sized particles but not nanometer sized particles. © 2014 The Authors. Journal of Biomedical Materials Research Part B: Applied Biomaterials Published by Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 102B: 1496–1505, 2014. PMID:24604838

Properties of CuInS₂ Nano-Particles on TiO₂ by Spray Pyrolysis for CuInS₂/TiO₂ Composite Solar Cell.

PubMed

Park, Gye-Choon; Li, Zhen-Yu; Yang, O-Bong

2017-04-01

In this letter, for the absorption layer of a CuInS₂/TiO₂ composite solar cell, I–III–VI2 chalcopyrite semiconductor CuInS₂ nano-particles were deposited by using spray pyrolysis method on TiO2 porous film. Their material characteristics including structural and optical properties of CuInS₂ nano-particles on TiO₂ nanorods were analyzed as a function of its composition ratios of Cu:In:S. Crystalline structure, surface morphology and crystalline size were also investigated by X-ray Diffraction (XRD), Field Emission Scanning Electron Microscope (FESEM), and High-Resolution TEM (HRTEM), respectively. On the other hand, optical property was characterized by an UV-Visible Spectrophotometer. As a result, it was found that the size of CuInS₂ nano-particles, which was formed at 300±5 °C, was smaller than 16 nm from HRTEM analyses, and it was identified that the CuInS₂ particle size was increased as increasing the heat-treatment temperature and time. However, as the size of CuInS₂ nano-particle becomes smaller, optical absorption edge of ternary compound film tends to move to the blue wavelength band. It turns out that the optical energy-band gap of the compound films was ranging from 1.48 eV to 1.53 eV.

Effect of TiC nano-particles on the mechanical properties of an Al-5Cu alloy after various heat treatments

NASA Astrophysics Data System (ADS)

Zhang, Qingquan; Zhang, Wei; Tian, Weisi; Zhao, Qinglong

2017-12-01

In this paper, the effects of TiC nano-particles on the mechanical properties of Al-5Cu alloy were investigated. Adding TiC nano-particles can effectively refine grain size and secondary dendritic arm. The ultimate tensile strength, yield strength and elongation of the Al-5Cu alloy in each of the three states (i.e. as-cast, solid-solution state and T6 state) were also improved by adding TiC nano-particles. Moreover, the elastic-plastic plane-strain fracture toughness (K J) and work of fracture ( wof) of Al-5Cu containing TiC were significantly higher than those of Al-5Cu without TiC after aging for 10 h. The addition of TiC nano-particles also led to finer and denser ‧ precipitates.

On the use of high-gradient magnetic force field in capturing airborne particles

DOE PAGES

Cheng, Mengdawn; Murphy, Bart L.; Moon, Ji Won; ...

2018-06-01

Airborne particles in the environment are generally smaller than a couple of microns. Use of magnetic force to collect aerosol particles thus has not been popular as the other means. There are billions of airborne particles emitted by a host of man-made sources with the particle size smaller than 1 µm and possess some magnetic susceptibility. We are thus interested in the use of high-gradient magnetic collection to extract the magnetic fraction in an aerosol population. Here in this study, we reported that the magnetic force is the dominant force in collection of ferromagnetic particles of mobility equivalent size largermore » than or equal to 50 nm in a high-gradient permanent-magnetic aerosol collector, while the diffusiophoretic force is responsible for particles smaller than 10 nm. Both forces compete for particles in between these two sizes in the magnetic aerosol collector designed for this study. To enable a wide-range effective collection of aerosol particles across entire size spectrum from a few nanometers to tens of a micron, the ORNL-designed high-gradient magnetic collector would require the use of an engineered matrix. Thus, the matrix design for a specific application becomes application specific. Irrespective of the collection efficiency, the use of permanent magnets to collect magnetic particles is feasible and also highly selective because it tunes into the magnetic susceptibility of the particles as well as the size. Lastly, the use of permanent magnets enables the collector to be operated at a minimal power requirement, which is a critical factor in long-term field operation.« less

On the use of high-gradient magnetic force field in capturing airborne particles

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

Cheng, Mengdawn; Murphy, Bart L.; Moon, Ji Won

Airborne particles in the environment are generally smaller than a couple of microns. Use of magnetic force to collect aerosol particles thus has not been popular as the other means. There are billions of airborne particles emitted by a host of man-made sources with the particle size smaller than 1 µm and possess some magnetic susceptibility. We are thus interested in the use of high-gradient magnetic collection to extract the magnetic fraction in an aerosol population. Here in this study, we reported that the magnetic force is the dominant force in collection of ferromagnetic particles of mobility equivalent size largermore » than or equal to 50 nm in a high-gradient permanent-magnetic aerosol collector, while the diffusiophoretic force is responsible for particles smaller than 10 nm. Both forces compete for particles in between these two sizes in the magnetic aerosol collector designed for this study. To enable a wide-range effective collection of aerosol particles across entire size spectrum from a few nanometers to tens of a micron, the ORNL-designed high-gradient magnetic collector would require the use of an engineered matrix. Thus, the matrix design for a specific application becomes application specific. Irrespective of the collection efficiency, the use of permanent magnets to collect magnetic particles is feasible and also highly selective because it tunes into the magnetic susceptibility of the particles as well as the size. Lastly, the use of permanent magnets enables the collector to be operated at a minimal power requirement, which is a critical factor in long-term field operation.« less

Self-assembly of smallest magnetic particles

PubMed Central

Mehdizadeh Taheri, Sara; Michaelis, Maria; Friedrich, Thomas; Förster, Beate; Drechsler, Markus; Römer, Florian M.; Bösecke, Peter; Narayanan, Theyencheri; Weber, Birgit; Rehberg, Ingo; Rosenfeldt, Sabine; Förster, Stephan

2015-01-01

The assembly of tiny magnetic particles in external magnetic fields is important for many applications ranging from data storage to medical technologies. The development of ever smaller magnetic structures is restricted by a size limit, where the particles are just barely magnetic. For such particles we report the discovery of a kind of solution assembly hitherto unobserved, to our knowledge. The fact that the assembly occurs in solution is very relevant for applications, where magnetic nanoparticles are either solution-processed or are used in liquid biological environments. Induced by an external magnetic field, nanocubes spontaneously assemble into 1D chains, 2D monolayer sheets, and large 3D cuboids with almost perfect internal ordering. The self-assembly of the nanocubes can be elucidated considering the dipole–dipole interaction of small superparamagnetic particles. Complex 3D geometrical arrangements of the nanodipoles are obtained under the assumption that the orientation of magnetization is freely adjustable within the superlattice and tends to minimize the binding energy. On that basis the magnetic moment of the cuboids can be explained. PMID:26554000

Synthesis of suitable SiO2 nano particles as the core in core-shell nanostructured materials.

PubMed

Ghahari, Mehdi; Aghababazadeh, Roya; Ebadzadeh, Touradj; Mirhabibi, Alireza; Brydson, Rik; Fabbri, Paola; Najafi, Farhod

2011-06-01

The effect of surfactant on the luminescent intensity of SiO2 @Y2O3:Eu3+ particles with a core shell structure is described. Core-shell particles are used in phosphor materials and employing spherical particles with a narrow size distribution is vital for the enhancement of luminescent properties. Three kinds of different surfactants were used to synthesis SiO2 nano particles via a sol gel process. The results demonstrated that comb polycarboxylic acid surfactant had a significant influence on the morphology and particle size distribution. Somehow, particles with 100 nm size and narrow size distribution were produced. These particles had relatively uniform packing, unlike particles produced with other surfactants or without surfactant which had irregular assembly. The photoluminescence intensity of SiO2 @Y2O3:Eu3+ particles that was synthesized by comb polycarboxylic acid surfactant was higher than those which were produced without surfactant.

Effect of nano/micro B4C and SiC particles on fracture properties of aluminum 7075 particulate composites under chevron-notch plane strain fracture toughness test

NASA Astrophysics Data System (ADS)

Morovvati, M. R.; Lalehpour, A.; Esmaeilzare, A.

2016-12-01

Reinforcing aluminum with SiC and B4C nano/micro particles can lead to a more efficient material in terms of strength and light weight. The influence of adding these particles to an aluminum 7075 matrix is investigated using chevron-notch fracture toughness test method. The reinforcing factors are type, size (micro/nano), and weight percent of the particles. The fracture parameters are maximum load, notch opening displacement, the work up to fracture and chevron notch plane strain fracture toughness. The findings demonstrate that addition of micro and nano size particles improves the fracture properties; however, increasing the weight percent of the particles leads to increase of fracture properties up to a certain level and after that due to agglomeration of the particles, the improvement does not happen for both particle types and size categories. Agglomeration of particles at higher amounts of reinforcing particles results in improper distribution of particles and reduction in mechanical properties.

Fe–Ni solid solutions in nano-size dimensions: Effect of hydrogen annealing

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

Kumar, Asheesh, E-mail: asheeshk@barc.gov.in; Meena, S.S.; Banerjee, S.

Highlights: • Fe–Ni solid solution with nano-size dimensions were prepared and characterized. • Both as prepared and hydrogenated solid solutions have FCC structure of Ni. • Paramagnetic and ferromagnetic domains coexist in these samples. - Abstract: Nanoparticles of Ni{sub 0.50}Fe{sub 0.50} and Ni{sub 0.75}Fe{sub 0.25} alloys were prepared by chemical reduction in ethylene glycol medium. XRD and {sup 57}Fe Mössbauer studies have confirmed the formation of Fe–Ni solid solution in nano-size dimensions with FCC structure. These samples consist of both ferromagnetic and paramagnetic domains which have been attributed to the coexistence of large and small particles as confirmed by atomicmore » force microscopic (AFM) and {sup 57}Fe Mössbauer spectroscopic studies. Improved extent of Fe–Fe exchange interaction existing in Ni{sub 0.50}Fe{sub 0.50} alloy compared to Ni{sub 0.75}Fe{sub 0.25} alloy explains the observed increase in the relative extent of ferromagnetic domains compared to paramagnetic domains in the former sample. Increase in the relative extent of ferromagnetic domains for hydrogenated alloys is due to increase in particle size brought about by the high temperature activation prior to hydrogenation.« less

Bidirectional particle transport and size selective sorting of Brownian particles in a flashing spatially periodic energy landscape.

PubMed

Martinez-Pedrero, Fernando; Massana-Cid, Helena; Ziegler, Till; Johansen, Tom H; Straube, Arthur V; Tierno, Pietro

2016-09-29

We demonstrate a size sensitive experimental scheme which enables bidirectional transport and fractionation of paramagnetic colloids in a fluid medium. It is shown that two types of magnetic colloidal particles with different sizes can be simultaneously transported in opposite directions, when deposited above a stripe-patterned ferrite garnet film subjected to a square-wave magnetic modulation. Due to their different sizes, the particles are located at distinct elevations above the surface, and they experience two different energy landscapes, generated by the modulated magnetic substrate. By combining theoretical arguments and numerical simulations, we reveal such energy landscapes, which fully explain the bidirectional transport mechanism. The proposed technique does not require pre-imposed channel geometries such as in conventional microfluidics or lab-on-a-chip systems, and permits remote control over the particle motion, speed and trajectory, by using relatively low intense magnetic fields.

Magnetic Nano-Materials: Truly Sustainable Green Chemistry Nano Catalysis

EPA Science Inventory

We envisioned a novel nano-catalyst system, which can bridge the homogenous and heterogeneous system, and simultaneously be cheaper, easily accessible (sustainable) and possibly does not require elaborate work-up. Because of its nano-size, i.e. high surface area, the contact betw...

Quadrupole magnetic field-flow fractionation: A novel technique for the characterization of magnetic particles

NASA Astrophysics Data System (ADS)

Carpino, Francesca

In the last few decades, the development and use of nanotechnology has become of increasing importance. Magnetic nanoparticles, because of their unique properties, have been employed in many different areas of application. They are generally made of a core of magnetic material coated with some other material to stabilize them and to help disperse them in suspension. The unique feature of magnetic nanoparticles is their response to a magnetic field. They are generally superparamagnetic, in which case they become magnetized only in a magnetic field and lose their magnetization when the field is removed. It is this feature that makes them so useful for drug targeting, hyperthermia and bioseparation. For many of these applications, the synthesis of uniformly sized magnetic nanoparticles is of key importance because their magnetic properties depend strongly on their dimensions. Because of the difficulty of synthesizing monodisperse particulate materials, a technique capable of characterizing the magnetic properties of polydisperse samples is of great importance. Quadrupole magnetic field-flow fractionation (MgFFF) is a technique capable of fractionating magnetic particles based on their content of magnetite or other magnetic material. In MgFFF, the interplay of hydrodynamic and magnetic forces separates the particles as they are carried along a separation channel. Since the magnetic field and the gradient in magnetic field acting on the particles during their migration are known, it is possible to calculate the quantity of magnetic material in the particles according to their time of emergence at the channel outlet. Knowing the magnetic properties of the core material, MgFFF can be used to determine both the size distribution and the mean size of the magnetic cores of polydisperse samples. When magnetic material is distributed throughout the volume of the particles, the derived data corresponds to a distribution in equivalent spherical diameters of magnetic material in

Pb(II) sorption from aqueous solution by novel biochar loaded with nano-particles.

PubMed

Wang, Chongqing; Wang, Hui

2018-02-01

Novel sorbent (HBC) is prepared by introducing nano-particles (Maghemite and EDTA functionalized layered double hydroxides) on biochar surface. FTIR, XRD, SEM and EDS are used to characterize the biochar nanocomposites. Pb(II) sorption is highly dependent on solution pH. Sorption kinetics and isotherms indicate that Pb(II) sorption onto the sorbents follows pseudo-second order model and Langmuir isotherm. The maximum sorption capacity of Pb(II) onto HBC is up to146.84 mg g -1 , higher than previously reported sorbents. The magnetic particles enable easy separation of HBC from aqueous solution by external magnetic fields. HBC can be used as effective sorbent for removal of heavy metals from wastewater. Copyright © 2017 Elsevier Ltd. All rights reserved.

Hemoglobin level and lipoprotein particle size.

PubMed

Hämäläinen, Päivi; Saltevo, Juha; Kautiainen, Hannu; Mäntyselkä, Pekka; Vanhala, Mauno

2018-01-10

Alterations in lipoprotein size are associated with increased cardiovascular disease risk. Higher hemoglobin levels may indicate a higher risk of atherosclerosis and was previously associated with obesity, metabolic syndrome, and insulin resistance. No previous studies have investigated an association between hemoglobin concentration and lipoprotein particle size. We conducted a population-based, cross-sectional study of 766 Caucasian, middle-aged subjects (341 men and 425 women) born in Pieksämäki, Finland, who were categorized into five age groups. The concentrations and sizes of lipoprotein subclass particles were analyzed by high-throughput nuclear magnetic resonance (NMR) spectroscopy. Larger very low density lipoprotein (VLDL) particle diameter was associated with higher hemoglobin concentrations in men (p = 0.003). There was a strong relationship between smaller high density lipoprotein (HDL) particle size and higher hemoglobin concentration in both men and women as well as with smaller low density lipoprotein (LDL) particle size and higher hemoglobin concentration in men and women (p < 0.001; p = 0.009, p = 0.008). VLDL particle concentration had a moderate positive correlation with hemoglobin concentration (r = 0.15; p < 0.001). LDL particle concentration showed a statistical trend suggesting increasing particle concentration with increasing hemoglobin levels (r = 0.08; p = 0.05). Higher hemoglobin levels are associated with larger VLDL, smaller LDL, and smaller HDL particle sizes and increasing amounts of larger VLDL and smaller LDL particles. This suggests that a higher hemoglobin concentration is associated with an unfavorable lipoprotein particle profile that is part of states that increase cardiovascular disease risk like diabetes and metabolic syndrome.

Coal emissions adverse human health effects associated with ultrafine/nano-particles role and resultant engineering controls.

PubMed

Oliveira, Marcos L S; Navarro, Orlando G; Crissien, Tito J; Tutikian, Bernardo F; da Boit, Kátia; Teixeira, Elba C; Cabello, Juan J; Agudelo-Castañeda, Dayana M; Silva, Luis F O

2017-10-01

There are multiple elements which enable coal geochemistry: (1) boiler and pollution control system design parameters, (2) temperature of flue gas at collection point, (3) feed coal and also other fuels like petroleum coke, tires and biomass geochemistry and (4) fuel feed particle size distribution homogeneity distribution, maintenance of pulverisers, etc. Even though there is a large number of hazardous element pollutants in the coal-processing industry, investigations on micrometer and nanometer-sized particles including their aqueous colloids formation reactions and their behaviour entering the environment are relatively few in numbers. X-ray diffraction (XRD), High Resolution-Transmission Electron microscopy (HR-TEM)/ (Energy Dispersive Spectroscopy) EDS/ (selected-area diffraction pattern) SAED, Field Emission-Scanning Electron Microscopy (FE-SEM)/EDS and granulometric distribution analysis were used as an integrated characterization techniques tool box to determine both geochemistry and nanomineralogy for coal fly ashes (CFAs) from Brazil´s largest coal power plant. Ultrafine/nano-particles size distribution from coal combustion emissions was estimated during the tests. In addition the iron and silicon content was determined as 54.6% of the total 390 different particles observed by electron bean, results aimed that these two particles represent major minerals in the environment particles normally. These data may help in future investigations to asses human health actions related with nano-particles. Copyright © 2017 Elsevier Inc. All rights reserved.

Synthesis and characterization of CdO nano particles by the sol-gel method

NASA Astrophysics Data System (ADS)

Vadgama, V. S.; Vyas, R. P.; Jogiya, B. V.; Joshi, M. J.

2017-05-01

Cadmium Oxide (CdO) is an inorganic compound and one of the main precursors to other cadmium compounds. It finds applications in cadmium plating, storage batteries, in transparent conducting film, etc. Here, an attempt is made to synthesize CdO nano particles by sol-gel technique. The gel was prepared using cadmium nitrate tetra hydrate (Cd(NO3)2.4H2O) and aqueous ammonium hydroxide (NH4OH) as a precursor. The synthesized powder is further characterized by techniques like Powder X-ray diffraction (XRD), Transmission electron microscopy (TEM), Fourier transform infrared spectroscopy (FT-IR) and Thermal gravimetric analysis (TGA). Powder XRD analysis suggested the nano-crystalline nature of the sample with the cubic crystal system. Nano scaled particles of spherical morphology with the size ranging from 50-100 nm are observed from TEM images. While, FT-IR study is used to confirm the presence of different functional groups. Thermo-gravimetric analysis suggests the highly thermally stable nature of the samples. The results are discussed.

Self assembly of nano metric metallic particles for realization of photonic and electronic nano transistors.

PubMed

Shahmoon, Asaf; Limon, Ofer; Girshevitz, Olga; Zalevsky, Zeev

2010-05-25

In this paper, we present the self assembly procedure as well as experimental results of a novel method for constructing well defined arrangements of self assembly metallic nano particles into sophisticated nano structures. The self assembly concept is based on focused ion beam (FIB) technology, where metallic nano particles are self assembled due to implantation of positive gallium ions into the insulating material (e.g., silica as in silicon on insulator wafers) that acts as intermediary layer between the substrate and the negatively charge metallic nanoparticles.

Coupling Fe0 nano particles with living and dead Azolla filicoloides to improve removal of methylene blue from aqueous solution

NASA Astrophysics Data System (ADS)

Rakhshaee, Roohan

2015-11-01

Fe0 nano particles (FNPs) were connected to the cell wall of the dead and living Azolla filicoloides as an aquatic fern, individually. FNPs mean size was decreased due to the stabilization, especially using the living one. It was compared the results of X-ray photoelectron spectroscopy (XPS), saturation magnetization (Ms), zeta potential (ZP) and thermal analysis (DSC and TGA) of the dead and living Azolla connected to FNPs, and also the findings of potentiometric titration (PT) of the cell wall's pectin of the dead and living Azolla. It was confirmed (by XRD and XPS) that Fe0 nano particles when were connected to the living Azolla did not produce Fe3O4 due to oxidation unlike the bare FNPs and the connected form to the dead Azolla, by reason of the more stabilization (more surface protection) of nano iron particles after connecting to the living Azolla. To adsorb methylene blue by these agents at the optimum pre-treatment pH 10 and adsorption pH 8, the parameters of equilibrium sorption, rate constant of second-order sorption and activation energy were obtained as: living Azolla-FNPs > dead Azolla-FNPs > FNPs > dead Azolla, while, their thermodynamic parameters (ΔG°, ΔH° and ΔS°) had the reverse arrangement. It was also studied the various factors rule such as photoperiod and the presence of heavy metals on the living Azolla growth coupled with FNPs and its MB removal ability.

Deposition of gold nano-particles and nano-layers on polyethylene modified by plasma discharge and chemical treatment

NASA Astrophysics Data System (ADS)

Švorčík, V.; Chaloupka, A.; Záruba, K.; Král, V.; Bláhová, O.; Macková, A.; Hnatowicz, V.

2009-08-01

Polyethylene (PE) was treated in Ar plasma discharge and then grafted from methanol solution of 1,2-ethanedithiol to enhance adhesion of gold nano-particles or sputtered gold layers. The modified PE samples were either immersed into freshly prepared colloid solution of Au nano-particles or covered by sputtered, 50 nm thick gold nano-layer. Properties of the plasma modified, dithiol grafted and gold coated PE were studied using XPS, UV-VIS, AFM, EPR, RBS methods and nanoindentation. It was shown that the plasma treatment results in degradation of polymer chain, creation of excessive free radicals and conjugated double bonds. After grafting with 1,2-ethanedithiol the concentration of free radicals declined but the concentration of double bonds remained unchanged. Plasma treatment changes PE surface morphology and increases surface roughness too. Another significant change in the surface morphology and roughness was observed after deposition of Au nano-particles. The presence of Au on the sample surface after the coating with Au nano-particles was proved by XPS and RBS methods. Nanoindentation measurements shown that the grafting of plasma activated PE surface with dithiol increases significantly adhesion of sputtered Au nano-layer.

Self Assembly of Nano Metric Metallic Particles for Realization of Photonic and Electronic Nano Transistors

PubMed Central

Shahmoon, Asaf; Limon, Ofer; Girshevitz, Olga; Zalevsky, Zeev

2010-01-01

In this paper, we present the self assembly procedure as well as experimental results of a novel method for constructing well defined arrangements of self assembly metallic nano particles into sophisticated nano structures. The self assembly concept is based on focused ion beam (FIB) technology, where metallic nano particles are self assembled due to implantation of positive gallium ions into the insulating material (e.g., silica as in silicon on insulator wafers) that acts as intermediary layer between the substrate and the negatively charge metallic nanoparticles. PMID:20559513

Method of producing carbon coated nano- and micron-scale particles

DOEpatents

Perry, W. Lee; Weigle, John C; Phillips, Jonathan

2013-12-17

A method of making carbon-coated nano- or micron-scale particles comprising entraining particles in an aerosol gas, providing a carbon-containing gas, providing a plasma gas, mixing the aerosol gas, the carbon-containing gas, and the plasma gas proximate a torch, bombarding the mixed gases with microwaves, and collecting resulting carbon-coated nano- or micron-scale particles.

MD Simulation on Collision Behavior Between Nano-Scale TiO₂ Particles During Vacuum Cold Spraying.

PubMed

Yao, Hai-Long; Yang, Guan-Jun; Li, Chang-Jiu

2018-04-01

Particle collision behavior influences significantly inter-nano particle bonding formation during the nano-ceramic coating deposition by vacuum cold spraying (or aerosol deposition method). In order to illuminate the collision behavior between nano-scale ceramic particles, molecular dynamic simulation was applied to explore impact process between nano-scale TiO2 particles through controlling impact velocities. Results show that the recoil efficiency of the nano-scale TiO2 particle is decreased with the increase of the impact velocity. Nano-scale TiO2 particle exhibits localized plastic deformation during collision at low velocities, while it is intensively deformed by collision at high velocities. This intensive deformation promotes the nano-particle adhesion rather than rebounding off. A relationship between the adhesion energy and the rebound energy is established for the bonding formation of the nano-scale TiO2 particle. The adhesion energy required to the bonding formation between nano-scale ceramic particles can be produced by high velocity collision.

Size effects on the magnetic properties of LaCoO3 nanoparticles

NASA Astrophysics Data System (ADS)

Wei, Q.; Zhang, T.; Wang, X. P.; Fang, Q. F.

2012-02-01

Magnetic properties of LaCoO3 nanoparticles prepared by a sol-gel method with average particle size (D) ranging from 20 to 500 nm are investigated. All samples exhibit obvious ferromagnetic transition. With decreasing particle size from 500 to 120 nm, the transition temperature Tc decreases slightly from 85 K, however Tc decreases dramatically when D ≤ 85 nm. Low-field magnetic moment at 10 K decreases with reduction of particle size, while the high-field magnetization exhibits a converse behavior, which is different with previous reports. The coercivity Hc decreases as the particle size is reduced. It is different with other nanosystems that no exchange bias effect is observed in nanosized LaCoO3 particles. These interesting results arise from the surface effect induced by sized effect and the structure change in LaCoO3 nanoparticles.

Melatonin potentiates "inside-out" nano-thermotherapy in human breast cancer cells: a potential cancer target multimodality treatment based on melatonin-loaded nanocomposite particles.

PubMed

Xie, Wensheng; Gao, Qin; Wang, Dan; Wang, Wei; Yuan, Jie; Guo, Zhenhu; Yan, Hao; Wang, Xiumei; Sun, Xiaodan; Zhao, Lingyun

2017-01-01

With the wide recognition of oncostatic effect of melatonin, the current study proposes a potential breast cancer target multimodality treatment based on melatonin-loaded magnetic nanocomposite particles (Melatonin-MNPs). Melatonin-MNPs were fabricated by the single emulsion solvent extraction/evaporation method. Based on the facilitated transport of melatonin by the GLUT overexpressed on the cell membrane, such Melatonin-MNPs can be more favorably uptaken by MCF-7 cells compared with the melatonin-free nanocomposite particles, which indicates the cancer targeting ability of melatonin molecule. Inductive heating can be generated by exposure to the Melatonin-MNPs internalized within cancer cells under alternative magnetic field, so as to achieve the "inside-out" magnetic nano-thermotherapy. In addition to demonstrating the superior cytotoxic effect of such nano-thermotherapy over the conventional exogenous heating by metal bath, more importantly, the sustainable release of melatonin from the Melatonin-MNPs can be greatly promoted upon responsive to the magnetic heating. The multimodality treatment based on Melatonin-MNPs can lead to more significant decrease in cell viability than any single treatment, suggesting the potentiated effect of melatonin on the cytotoxic response to nano-thermotherapy. This study is the first to fabricate the precisely engineered melatonin-loaded multifunctional nanocomposite particles and demonstrate the potential in breast cancer target multimodality treatment.

Particle size related bacterial recovery in immunomagnetic separation

USDA-ARS?s Scientific Manuscript database

Magnetic nanoparticles (MNPs) have demonstrated superior capture efficiencies in small molecule targets during immunomagnetic separation (IMS), but the potentials of MNPs in bacterial isolation have not been verified. The objective of this study was to evaluate the effect of magnetic particle size o...

Multimodal magnetic nano-carriers for cancer treatment: Challenges and advancements

NASA Astrophysics Data System (ADS)

Aadinath, W.; Ghosh, Triroopa; Anandharamakrishnan, C.

2016-03-01

Iron oxide nanoparticles (IONPs) have been a propitious topic for cancer treatment in recent years because of its multifunctional theranostic applications under magnetic field. Two such widely used applications in cancer biology are gradient magnetic field guided targeting and alternative magnetic field (AMF) induced local hyperthermia. Gradient magnetic field guided targeting is a mode of active targeting of therapeutics conjugated with iron oxide nanoparticles. These particles also dissipate heat in presence of AMF which causes thermal injury to the cells of interest, for example tumour cells and subsequent death. Clinical trials divulge the feasibility of such magnetic nano-carrier as a promising candidate in cancer biology. However, these techniques need further investigations to curtail certain limitations manifested. Recent progresses in response have shrunken the barricade to certain extent. In this context, principles, challenges associated with these applications and recent efforts made in response will be discussed.

Nano iron particles transport in fractured rocks: laboratory and field scale

NASA Astrophysics Data System (ADS)

Cohen, Meirav; Weisbrod, Noam

2017-04-01

Our study deals with the transport potential of nano iron particles (NIPs) in fractured media. Two different systemswere used to investigate transport on two scales: (1 )a laboratory flow system of a naturally discrete fractured chalk core, 0.43 and 0.18 m in length and diamater, respectively; and (2) a field system of hydraulically connected boreholes located 47 m apart which penetrate a fractured chalk aquifer. We started by testing the transport potential of various NIPs under different conditions. Particle stability experiments were conducted using various NIPs and different stabilizersat two ionic strengths. Overall, four different NIPs and three stabilizers were tested. Particles and solution properties (stability, aggregate/particle size, viscosity and density) were tested in batch experiments, and transport experiments (breakthrough curves (BTCs) and recovery) were conduted in the fractured chalk core. We have learned that the key parameters controlling particle transport are the particle/aggregate size and stability, which govern NIP settling rates and ultimately their migration distance. The governing mechanism controlling NIP transport was found to be sedimentation, and to a much lesser extent, processes such as diffusion, straining or interception. On the basis of these experiments, Carbo-Iron® particles ( 800 nm activated carbon particles doped with nano zero valent iron particles) and Carboxymethyl cellulose (CMC) stabilizer were selected for the field test injection. In the field, Carbo-Iron particles were initially injected into the fractured aquifer using an excess of stabilizer in order to ensure maximum recovery. This resulted in high particle recovery and fast arrival time, similar to the ideal tracer (iodide). The high recovery of the stable particle solution emphasized the importance of particle stability for transport in fractures. To test mobility manipulation potential of the particles and simulate more realistic scenarios, a second field

Magnetic separation of encapsulated islet cells labeled with superparamagnetic iron oxide nano particles.

PubMed

Mettler, Esther; Trenkler, Anja; Feilen, Peter J; Wiegand, Frederik; Fottner, Christian; Ehrhart, Friederike; Zimmermann, Heiko; Hwang, Yong Hwa; Lee, Dong Yun; Fischer, Stefan; Schreiber, Laura M; Weber, Matthias M

2013-01-01

Islet cell transplantation is a promising option for the restoration of normal glucose homeostasis in patients with type 1 diabetes. Because graft volume is a crucial issue in islet transplantations for patients with diabetes, we evaluated a new method for increasing functional tissue yield in xenogeneic grafts of encapsulated islets. Islets were labeled with three different superparamagnetic iron oxide nano particles (SPIONs; dextran-coated SPION, siloxane-coated SPION, and heparin-coated SPION). Magnetic separation was performed to separate encapsulated islets from the empty capsules, and cell viability and function were tested. Islets labeled with 1000 μg Fe/ml dextran-coated SPIONs experienced a 69.9% reduction in graft volume, with a 33.2% loss of islet-containing capsules. Islets labeled with 100 μg Fe/ml heparin-coated SPIONs showed a 46.4% reduction in graft volume, with a 4.5% loss of capsules containing islets. No purification could be achieved using siloxane-coated SPIONs due to its toxicity to the primary islets. SPION labeling of islets is useful for transplant purification during islet separation as well as in vivo imaging after transplantation. Furthermore, purification of encapsulated islets can also reduce the volume of the encapsulated islets without impairing their function by removing empty capsules. © 2013 John Wiley & Sons A/S.

Nano-sized Contrast Agents to Non-Invasively Detect Renal Inflammation by Magnetic Resonance Imaging

PubMed Central

Thurman, Joshua M.; Serkova, Natalie J.

2013-01-01

Several molecular imaging methods have been developed that employ nano-sized contrast agents to detect markers of inflammation within tissues. Renal inflammation contributes to disease progression in a wide range of autoimmune and inflammatory diseases, and a biopsy is currently the only method of definitively diagnosing active renal inflammation. However, the development of new molecular imaging methods that employ contrast agents capable of detecting particular immune cells or protein biomarkers will allow clinicians to evaluate inflammation throughout the kidneys, and to assess a patient's response to immunomodulatory drugs. These imaging tools will improve our ability to validate new therapies and to optimize the treatment of individual patients with existing therapies. This review describes the clinical need for new methods of monitoring renal inflammation, and recent advances in the development of nano-sized contrast agents for detection of inflammatory markers of renal disease. PMID:24206601

Efficient recovery of nano-sized iron oxide particles from synthetic acid-mine drainage (AMD) water using fuel cell technologies.

PubMed

Cheng, Shaoan; Jang, Je-Hun; Dempsey, Brian A; Logan, Bruce E

2011-01-01

Acid mine drainage (AMD) is an important contributor to surface water pollution due to the release of acid and metals. Fe(II) in AMD reacts with dissolved oxygen to produce iron oxide precipitates, resulting in further acidification, discoloration of stream beds, and sludge deposits in receiving waters. It has recently been shown that new fuel cell technologies, based on microbial fuel cells, can be used to treat AMD and generate electricity. Here we show that this approach can also be used as a technique to generate spherical nano-particles of iron oxide that, upon drying, are transformed to goethite (α-FeOOH). This approach therefore provides a relatively straightforward way to generate a product that has commercial value. Particle diameters ranged from 120 to 700 nm, with sizes that could be controlled by varying the conditions in the fuel cell, especially current density (0.04-0.12 mA/cm(2)), pH (4-7.5), and initial Fe(II) concentration (50-1000 mg/L). The most efficient production of goethite and power occurred with pH = 6.3 and Fe(II) concentrations above 200 mg/L. These results show that fuel cell technologies can not only be used for simultaneous AMD treatment and power generation, but that they can generate useful products such as iron oxide particles having sizes appropriate for used as pigments and other applications. Copyright © 2010 Elsevier Ltd. All rights reserved.

Magnetization Reversal Process of Single Crystal α-Fe Containing a Nonmagnetic Particle

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

Li, Yi; Xu, Ben; Hu, Shenyang Y.

2015-09-25

The magnetization reversal process and hysteresis loops in a single crystal α-iron with nonmagnetic particles are simulated in this work based on the Landau-Lifshitz–Gilbert equation. The evolutions of the magnetic domain morphology are studied, and our analyses show that the magnetization reversal process is affected by the interaction between the moving domain wall and the existing nonmagnetic particles. This interaction strongly depends on the size of the particles, and it is found that particles with a particular size contribute the most to magnetic hardening.

Oleate-based hydrothermal preparation of CoFe2O4 nanoparticles, and their magnetic properties with respect to particle size and surface coating

NASA Astrophysics Data System (ADS)

Repko, Anton; Vejpravová, Jana; Vacková, Taťana; Zákutná, Dominika; Nižňanský, Daniel

2015-09-01

We present a facile and high-yield synthesis of cobalt ferrite nanoparticles by hydrothermal hydrolysis of Co-Fe oleate in the presence of pentanol/octanol/toluene and water at 180 or 220 °C. The particle size (6-10 nm) was controlled by the composition of the organic solvent and temperature. Magnetic properties were then investigated with respect to the particle size and surface modification with citric acid or titanium dioxide (leading to hydrophilic particles). The as-prepared hydrophobic nanoparticles (coated by oleic acid) had a minimum inter-particle distance of 2.5 nm. Their apparent blocking temperature (estimated as a maximum of the zero-field-cooled magnetization) was 180 K, 280 K and 330 K for the particles with size of 6, 9 and 10.5 nm, respectively. Replacement of oleic acid on the surface by citric acid decreased inter-particle distance to less than 1 nm, and increased blocking temperature by ca. 10 K. On the other hand, coating with titanium dioxide, supported by nitrilotri(methylphosphonic acid), caused increase of the particle spacing, and lowering of the blocking temperature by ca. 20 K. The CoFe2O4@TiO2 nanoparticles were sufficiently stable in water, methanol and ethanol. The particles were also investigated by Mössbauer spectroscopy and alternating-current (AC) susceptibility measurements, and their analysis with Vögel-Fulcher and power law. Effect of different particle coating and dipolar interactions on the magnetic properties is discussed.

3D Electromagnetic Particle-in-Cell simulations of the solar wind interaction with lunar magnetic anomalies

NASA Astrophysics Data System (ADS)

Deca, J.; Lapenta, G.; Divin, A. V.; Lembege, B.; Markidis, S.

2013-12-01

Unlike the Earth and Mercury, our Moon has no global magnetic field and is therefore not shielded from the impinging solar wind by a magnetosphere. However, lunar magnetic field measurements made by the Apollo missions provided direct evidence that the Moon has regions of small-scale crustal magnetic fields, ranging up to a few 100km in scale size with surface magnetic field strengths up to hundreds of nanoTeslas. More recently, the Lunar Prospector spacecraft has provided high-resolution observations allowing to construct magnetic field maps of the entire Moon, confirming the earlier results from Apollo, but also showing that the lunar plasma environment is much richer than earlier believed. Typically the small-scale magnetic fields are non-dipolar and rather tiny compared to the lunar radius and mainly clustered on the far side of the moon. Using iPic3D we present the first 3D fully kinetic and electromagnetic Particle-in-Cell simulations of the solar wind interaction with lunar magnetic anomalies. We study the behaviour of a dipole model with variable surface magnetic field strength under changing solar wind conditions and confirm that lunar crustal magnetic fields may indeed be strong enough to stand off the solar wind and form a mini-magnetosphere, as suggested by MHD and hybrid simulations and spacecraft observations. 3D-PIC simulations reveal to be very helpful to analyze the diversion/braking of the particle flux and the characteristics of the resulting particles accumulation. The particle flux to the surface is significantly reduced at the magnetic anomaly, surrounded by a region of enhanced density due to the magnetic mirror effect. Second, the ability of iPic3D to resolve all plasma components (heavy ions, protons and electrons) allows to discuss in detail the electron physics leading to the highly non-adiabatic interactions expected as well as the implications for solar wind shielding of the lunar surface, depending on the scale size (solar wind protons

Biofunctionalization of scaffold material with nano-scaled diamond particles physisorbed with angiogenic factors enhances vessel growth after implantation.

PubMed

Schimke, Magdalena M; Stigler, Robert; Wu, Xujun; Waag, Thilo; Buschmann, Peter; Kern, Johann; Untergasser, Gerold; Rasse, Michael; Steinmüller-Nethl, Doris; Krueger, Anke; Lepperdinger, Günter

2016-04-01

Biofunctionalized scaffold facilitates complete healing of large defects. Biological constraints are induction and ingrowth of vessels. Angiogenic growth factors such as vascular endothelial growth factor or angiopoietin-1 can be bound to nano-scaled diamond particles. Corresponding bioactivities need to be examined after biofunctionalization. We therefore determined the physisorptive capacity of distinctly manufactured, differently sized nDP and the corresponding activities of bound factors. The properties of biofunctionalized nDPs were investigated on cultivated human mesenchymal stem cells and on the developing chicken embryo chorio-allantoic membrane. Eventually porous bone substitution material was coated with nDP to generate an interface that allows biofactor physisorption. Angiopoietin-1 was applied shortly before scaffold implantation into an osseous defect in sheep calvaria. Biofunctionalized scaffolds exhibited significantly increased rates of angiogenesis already one month after implantation. Conclusively, nDP can be used to ease functionalization of synthetic biomaterials. With the advances in nanotechnology, many nano-sized materials have been used in the biomedical field. This is also true for nano-diamond particles (nDP). In this article, the authors investigated the physical properties of functionalized nano-diamond particles in both in-vitro and in-vivo settings. The positive findings would help improve understanding of these nanomaterials in regenerative medicine. Copyright © 2015 Elsevier Inc. All rights reserved.

Preparation of Nano-sized Bismuth-Doped Fe3O4 as an Excellent Magnetic Material for Supercapacitor Electrodes

NASA Astrophysics Data System (ADS)

Aghazadeh, Mustafa; Karimzadeh, Isa; Ganjali, Mohammad Reza

2018-03-01

Nano-sized Bi3+-doped iron oxide (n-Bi-IO) particles were prepared through a one-pot electrochemical procedure, and the product was evaluated using x-ray diffraction, field-emission scanning electron microscopy and energy-dispersive x-ray spectroscopy. Based on the analyses, the average size of the n-Bi-IO was determined to be 10 nm. Galvanostatic charge-discharge (GCD) evaluations revealed that the specific capacitance of the material reached 235 F g-1 at a discharge condition of 0.2 A g-1. n-Bi-IO had a 94.2% capacity retention after 2000 GCD cycles. Further vibrating sample magnetometery analyses showed that the product has enhanced superparamagnetic qualities (i.e. M r = 0.15 emu g-1 and H Ci = 2.71 G) in comparison to iron oxide nanoparticles (i.e. M r = 0.95 emu g-1 and H Ci = 14.62 G). Given the results, the product is considered to be a promising material for developing high performance supercapacitor electrodes.

Nano-Dust Analyzer For the Detection and Chemical Composition Measurement of Particles Originating in the Inner Heliosphere

NASA Astrophysics Data System (ADS)

O'Brien, Leela; Gruen, E.; Sternovsky, Z.; Horanyi, M.; Juhasz, A.; Eberhard, M.; Srama, R.

2013-10-01

The development of the Nano-Dust Analyzer (NDA) instrument and the results from the first laboratory testing and calibration are reported. The two STEREO spacecrafts have indicated that nanometer-sized dust particles, potentially with very high flux, are delivered to 1 AU from the inner solar system [Meyer-Vernet, N. et al., Solar Physics, 256, 463, 2009]. These particles are generated by collisional grinding or evaporation near the Sun and accelerated outward by the solar wind. The temporal variability reveals the complex interaction with the solar wind magnetic field within 1 AU and provides the means to learn about solar wind conditions and can supply additional parameters or verification for heliospheric magnetic field models. The composition analysis will report on the processes that generated the nanometer-sized particle. NDA is a highly sensitive dust analyzer that is developed under NASA's Heliophysics program. The instrument is a linear time-of-flight mass analyzer that utilizes dust impact ionization and is modeled after the Cosmic Dust Analyzer (CDA) on Cassini. By applying technologies implemented in solar wind instruments and coronagraphs, the highly sensitive dust analyzer will be able to be pointed toward the solar direction. A laboratory prototype has been built, tested, and calibrated at the dust accelerator facility at the University of Colorado, Boulder, using particles with 1 to over 50 km/s velocity. NDA is unique in its requirement to operate with the Sun in its field-of-view. A light trap system has been designed and optimized in terms of geometry and surface optical properties to mitigate Solar UV contribution to detector noise. In addition, results from laboratory tests performed with a 1 keV ion beam at the University of New Hampshire’s Space Sciences Facility confirm the effectiveness of the instrument’s solar wind particle rejection system.

[Effect of stability and dissolution of realgar nano-particles using solid dispersion technology].

PubMed

Guo, Teng; Shi, Feng; Yang, Gang; Feng, Nian-Ping

2013-09-01

To improve the stability and dissolution of realgar nano-particles by solid dispersion. Using polyethylene glycol 6000 and poloxamer-188 as carriers, the solid dispersions were prepare by melting method. XRD, microscopic inspection were used to determine the status of realgar nano-particles in solid dispersions. The content and stability test of As(2)0(3) were determined by DDC-Ag method. Hydride generation atomic absorption spectrometry was used to determine the content of Arsenic and investigated the in vitro dissolution behavior of solid dispersions. The results of XRD and microscopic inspection showed that realgar nano-particles in solid dispersions were amorphous. The dissolution amount and rate of Arsenic from realgar nano-particles of all solid dispersions were increased significantly, the reunion of realgar nano-particles and content of As(2)0(3) were reduced for the formation of solid dispersions. The solid dispersion of realgar nano-particles with poloxamer-188 as carriers could obviously improve stability, dissolution and solubility.

Nano-polarization-converter based on magnetic plasmon resonance excitation in an L-shaped slot antenna.

PubMed

Yang, Jing; Zhang, Jiasen

2013-04-08

We propose a nano-polarization-converter made of a resonant L-shaped slot antenna in a gold film and study its optical properties using the finite-difference time-domain method. Phase retardation between the fast and slow axes of the nano-polarization-converter originates from the simultaneous excitation of both single-surface first-order magnetic plasmon resonance mode and second-order magnetic plasmon resonance mode at the working wavelength. By adjusting the size of the slot antenna, which is still much smaller than the wavelength, the working wavelength can be tuned within a large wavelength range.

Enrichment of magnetic particles using temperature and magnetic field gradients induced by benchtop fabricated micro-electromagnets.

PubMed

Hosseini, A; Philpott, D N; Soleymani, L

2017-11-21

The active transport of analytes inside biosensing systems is important for reducing the response time and enhancing the limit-of-detection of these systems. Due to the ease of functionalization with bio-recognition agents and manipulation with magnetic fields, magnetic particles are widely used for active and directed transport of biological analytes. On-chip active electromagnets are ideally suited for manipulating magnetic particles in an automated and miniaturized fashion inside biosensing systems. Unfortunately, the magnetic force exerted by these devices decays rapidly as we move away from the device edges, and increasing the generated force to the levels necessary for particle manipulation requires a parallel increase in the applied current and the resultant Joule heating. In this paper, we designed a study to understand the combined role of thermal and magnetic forces on the movement of magnetic particles in order to extend the interaction distance of on-chip magnetic devices beyond the device edges. For this purpose, we used a rapid prototyping method to create an active/passive on-chip electromagnet with a micro/nano-structured active layer and a patterned ferromagnetic passive layer. We demonstrated that the measured terminal velocities of particles positioned near the electromagnet edge (∼5.5 μm) closely reflect the values obtained by multi-physics modelling. Interestingly, we observed a two orders of magnitude deviation between the experimental and modelling results for the terminal velocities of particles far from the electromagnet edge (∼55.5 μm). Heat modelling of the system using experimentally-measured thermal gradients indicates that this discrepancy is related to the enhanced fluid movement caused by thermal forces. This study enables the rational design of thermo-magnetic systems for thermally driving and magnetically capturing particles that are positioned at distances tens to hundreds of microns away from the edges of on-chip magnetic

Effect of iron particle size and volume fraction on the magnetic properties of Fe/silicate glass soft magnetic composites

NASA Astrophysics Data System (ADS)

Ding, Wei; Jiang, Longtao; Liao, Yaqin; Song, Jiabin; Li, Bingqing; Wu, Gaohui

2015-03-01

Fe/silicate glass soft magnetic composites (SMC) were fabricated by powder metallurgy with 1000 MPa pressure at room temperature, and then annealed at 700 °C for 90 min. The iron particles distributed uniformly in the composites, and have been separated from each other by a continuous silicate glass insulating layer. Fe/glass interface was well bonded and a quasi-continuous layer Fe3O4 and FeO exited. Very fine crystalline phases Na12Ca3Fe2(Si6O18)2 were formed in silicate glass. Composite containing 57 vol% 75 μm iron particles demonstrated highest resistivity of 7.8×10-3 Ω m. The μm, Bs and Bt increased while Hc of Fe/silicate glass composites decreased with the increase of average size of iron particles. The composite with highest amount (82 vol%) and largest average size (140 μm) of iron particles demonstrated best μm, Bs and Bt and Hc, which were 622, 1.57 T, 1.43 T, 278 A/m, respectively. The composite containing 57 vol% 75 μm iron particles demonstrated minimum core loss of 3.5 W/kg at 50 Hz and 28.1 W/kg at 400 Hz, while the composite containing 82 vol% 140 μm iron particles exhibited maximum core loss of 5.2 W/kg at 50 Hz and 67.7 W/kg at 400 Hz.

How comparable are size-resolved particle number concentrations from different instruments?

NASA Astrophysics Data System (ADS)

Hornsby, K. E.; Pryor, S. C.

2012-12-01

The need for comparability of particle size resolved measurements originates from multiple drivers including: (i) Recent suggestions that air quality standards for particulate matter should migrate from being mass-based to incorporating number concentrations. This move would necessarily be predicated on measurement comparability which is absolutely critical to compliance determination. (ii) The need to quantify and diagnose causes of variability in nucleation and growth rates in nano-particle experiments conducted in different locations. (iii) Epidemiological research designed to identify key parameters in human health responses to fine particle exposure. Here we present results from a detailed controlled laboratory instrument inter-comparison experiment designed to investigate data comparability in the size range of 2.01-523.3 nm across a range of particle composition, modal diameter and absolute concentration. Particle size distributions were generated using a TSI model 3940 Aerosol Generation System (AGS) diluted using zero air, and sampled using four TSI Scanning Mobility Particle Spectrometer (SMPS) configurations and a TSI model 3091 Fast Mobility Particle Sizer (FMPS). The SMPS configurations used two Electrostatic Classifiers (EC) (model 3080) attached to either a Long DMA (LDMA) (model 3081) or a Nano DMA (NDMA) (model 3085) plumbed to either a TSI model 3025A Butanol Condensed Particle Counting (CPC) or a TSI model 3788 Water CPC. All four systems were run using both high and low flow conditions, and were operated with both the internal diffusion loss and multiple charge corrections turned on. The particle compositions tested were sodium chloride, ammonium nitrate and olive oil diluted in ethanol. Particles of all three were generated at three peak concentration levels (spanning the range observed at our experimental site), and three modal particle diameters. Experimental conditions were maintained for a period of 20 minutes to ensure experimental

Enhanced copper micro/nano-particle mixed paste sintered at low temperature for 3D interconnects

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

Dai, Y. Y.; Anantha, P.; Tan, C. S., E-mail: tancs@ntu.edu.sg

2016-06-27

An enhanced copper paste, formulated by copper micro- and nano-particles mixture, is reported to prevent paste cracking and obtain an improved packing density. The particle mixture of two different sizes enables reduction in porosity of the micro-paste and resolves the cracking issue in the nano-paste. In-situ temperature and resistance measurements indicate that the mixed paste has a lower densification temperature. Electrical study also shows a ∼12× lower sheet resistance of 0.27 Ω/sq. In addition, scanning electron microscope image analysis confirms a ∼50% lower porosity, which is consistent with the thermal and electrical results. The 3:1 (micro:nano, wt. %) mixed pastemore » is found to have the strongest synergistic effect. This phenomenon is discussed further. Consequently, the mixed paste is a promising material for potential low temperature 3D interconnects fabrication.« less

Synthesis and LPG sensing properties of nano-sized cadmium oxide.

PubMed

Waghulade, R B; Patil, P P; Pasricha, Renu

2007-04-30

This paper reports the synthesis and liquid petroleum gas (LPG) sensing properties of nano-sized cadmium oxide (CdO). The nano-sized CdO powder was successfully synthesized by using a chemical co-precipitation method using cadmium acetate and the ammonium hydroxide, as starting materials and water as a carrier. The resulting nano-sized powder was characterized by X-ray diffraction (XRD) measurements and the transmission electron microscopy (TEM). The LPG sensing properties of the synthesized nano-sized CdO were investigated at different operating temperatures and LPG concentrations. It was found that the calcination temperature and the operating temperature significantly affect the sensitivity of the nano-sized CdO powder to the LPG. The sensitivity is found to be maximum when the calcination temperature was 400 degrees C. The sensitivity to 75ppm of LPG is maximum at an operating temperature 450 degrees C and it was found to be approximately 341%. The response and recovery times were found to be nearly 3-5s and 8-10s, respectively. The synthesized nano-sized CdO powder is able to detect up to 25ppm for LPG with reasonable sensitivity at an operating temperature 450 degrees C and it can be reliably used to monitor the concentration of LPG over the range (25-75ppm). The experimental results of the LPG sensing studies reveal that the nano-sized CdO powder synthesized by a simple co-precipitation method is a suitable material for the fabrication of the LPG sensor.

Effect of vanadium doping on structural and magnetic properties of defective nano-nickel ferrite

NASA Astrophysics Data System (ADS)

Heiba, Zein K.; Mohamed, Mohamed Bakr; Wahba, Adel Maher; Almalowi, M. I.

2018-04-01

Nano-nickel ferrites defected by vanadium doping (NiV x Fe2-1.67 x O4, 0 ≤ x ≤ 0.25) were prepared using a simple sol gel method. Rietveld analysis revealed a nonmonotonic change in lattice parameter, oxygen parameter and magnetization upon doping with vanadium. Cation distributions suggested from either Rietveld analysis or from experimental magnetic moments were in a good agreement. For low doping values ( x = 0.05), vanadium was residing mainly in octahedral sites, while for samples with vanadium content ( x ≥ 0.1) a significant part of vanadium ions resided at tetrahedral sites; a result which has been confirmed by the analysis of Fourier-transform infrared (FTIR) spectrums obtained for the samples. The transmission electron microscope (TEM) image showed fine spherical particles with size of ˜ 11 nm. All samples showed a superparamagnetic nature with a nonmonotonic change of either magnetization ( M S) or coercivity (H C) with the content of nonmagnetic V5+. The cation occupancies indicated presence of an enormous number of vacancies through doping with high valence cation V5+, making present samples potential electrodes for Li- or Na-ion batteries.

Preparation and Characterization of Pyrotechnics Binder-Coated Nano-Aluminum Composite Particles

NASA Astrophysics Data System (ADS)

Ye, Mingquan; Zhang, Shuting; Liu, Songsong; Han, Aijun; Chen, Xin

2017-07-01

The aim of this article is to protect the activity of nano-aluminum (Al) particles in solid rocket propellants and pyrotechnics. The morphology, structure, active aluminum content, and thermal and catalytic properties of the coated samples were characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), Fourier transform infrared spectroscopy (FTIR), thermogravimetry-differential scanning calorimetry (TG-DSC), and oxidation-reduction titration methods. The results indicated that nano-Al particles could be effectively coated with phenolic resin (PF), fluororubber (Viton B), and shellac through a solvent/nonsolvent method. The energetic composite particles have core-shell structures and the thickness of the coating film is about 5-15 nm. Analysis of the active Al content revealed that Viton B coating had a much better protective effect. The TG-DSC results showed that the energy amount and energy release rate of PF-, Viton B-, and shellac-coated Al particles were larger than those of the raw nano-Al particles. The catalytic effects of coated Al particles on the thermal decomposition of ammonium perchlorate (AP) were better than those of raw nano-Al particles, and the effect of shellac-coated Al particles was significantly better than that of Viton B-coated Al particles.

Repetitive heterocoagulation of oppositely charged particles for enhancement of magnetic nanoparticle loading into monodisperse silica particles.

PubMed

Matsumoto, Hideki; Nagao, Daisuke; Konno, Mikio

2010-03-16

Oppositely charged particles were repetitively heterocoagulated to fabricate highly monodisperse magnetic silica particles with high loading of magnetic nanoparticles. Positively charged magnetic nanoparticles prepared by surface modification with N-trimethoxysilylpropyl-N,N,N-trimethylammonium chloride (TSA) were used to heterocoagulate with silica particles under basic conditions to give rise to negative silica surface charge and prevent the oxidation of the magnetic nanoparticles. The resultant particles of silica core homogeneously coated with the magnetic nanoparticles were further coated with thin silica layer with sodium silicate in order to enhance colloidal stability and avoid desorption of the magnetic nanoparticles from the silica cores. Five repetitions of the heterocoagulation and the silica coating could increase saturation magnetization of the magnetic silica particles to 27.7 emu/g, keeping the coefficient of variation of particle sizes (C(V)) less than 6.5%. Highly homogeneous loading of the magnetic component was confirmed by measuring Fe-to-Si atomic ratios of individual particles with energy dispersive X-ray spectroscopy.

Nano-sized manganese oxides as biomimetic catalysts for water oxidation in artificial photosynthesis: a review

PubMed Central

Najafpour, Mohammad Mahdi; Rahimi, Fahimeh; Aro, Eva-Mari; Lee, Choon-Hwan; Allakhverdiev, Suleyman I.

2012-01-01

There has been a tremendous surge in research on the synthesis of various metal compounds aimed at simulating the water-oxidizing complex (WOC) of photosystem II (PSII). This is crucial because the water oxidation half reaction is overwhelmingly rate-limiting and needs high over-voltage (approx. 1 V), which results in low conversion efficiencies when working at current densities required for hydrogen production via water splitting. Particular attention has been given to the manganese compounds not only because manganese has been used by nature to oxidize water but also because manganese is cheap and environmentally friendly. The manganese–calcium cluster in PSII has a dimension of about approximately 0.5 nm. Thus, nano-sized manganese compounds might be good structural and functional models for the cluster. As in the nanometre-size of the synthetic models, most of the active sites are at the surface, these compounds could be more efficient catalysts than micrometre (or bigger) particles. In this paper, we focus on nano-sized manganese oxides as functional and structural models of the WOC of PSII for hydrogen production via water splitting and review nano-sized manganese oxides used in water oxidation by some research groups. PMID:22809849

The Evolution of Fabricated Gold Thin Films to Nano-Micro Particles Under Thermal Annealing Process

NASA Astrophysics Data System (ADS)

Hajivaliei, Mahdi; Nazari, Saeed

2016-06-01

Gold (Au) thin films with thickness of 35nm were prepared by electron beam deposition onto flat glass substrates under high vacuum (5.3×10-3Pa) condition and they were annealed in the range of 573-873 K for 1 and 2h in atmospheric pressure. The influence of the annealing temperature on the evolution of Au thin film to nano-micro particles was studied. Moreover, the basic properties of the films, namely morphological, structural and optical were investigated. The X-ray diffraction (XRD) analysis revealed that the Au thin films were cubic structure phase with lattice parameter around a=4.0786Å. The most preferential orientation is along (111) planes for all Au films. The lattice parameter and grain size in the films were calculated by X-ray patterns and correlated with annealing temperatures. The obtained results of ultraviolet-visible spectrometry (UV-Vis) indicate that with increasing annealing temperature, the surface plasmon resonance peak of gold nanocrystallite will disappear which implies the size of particles are grown. Field-emission scanning electron microscopy (FE-SEM) results show that the prepared gold thin films have been converted to nano-micro gold particles in different annealing temperatures. These results lead to controlling the size of produced nanocrystallite.

[Drug delivery systems using nano-sized drug carriers].

PubMed

Nakayama, Masamichi; Okano, Teruo

2005-07-01

Nanotechnology has attracted great attention all over the world in recent several years and has led to the establishment of the novel technical field of "nanomedicine" through collaboration with advanced medical technology. Particularly, site-specific drug targeting using particle drug carrier systems has made substantial progress and been actively developed. This review explains the essential factors (size and chemical character) of drug carriers to allow long circulation in the bloodstream avoiding the reticuloendothelial system, and shows the present status and future perspective of several types of nano-carrier systems (water-soluble polymer, liposome and polymeric micelle). We also introduce the novel concept of multi-targeting system (combination of two or more targeting methodologies) for ideal drug therapies.

Disaggregation and separation dynamics of magnetic particles in a microfluidic flow under an alternating gradient magnetic field

NASA Astrophysics Data System (ADS)

Cao, Quanliang; Li, Zhenhao; Wang, Zhen; Qi, Fan; Han, Xiaotao

2018-05-01

How to prevent particle aggregation in the magnetic separation process is of great importance for high-purity separation, while it is a challenging issue in practice. In this work, we report a novel method to solve this problem for improving the selectivity of size-based separation by use of a gradient alternating magnetic field. The specially designed magnetic field is capable of dynamically adjusting the magnetic field direction without changing the direction of magnetic gradient force acting on the particles. Using direct numerical simulations, we show that particles within a certain center-to-center distance are inseparable under a gradient static magnetic field since they are easy aggregated and then start moving together. By contrast, it has been demonstrated that alternating repulsive and attractive interaction forces between particles can be generated to avoid the formation of aggregations when the alternating gradient magnetic field with a given alternating frequency is applied, enabling these particles to be continuously separated based on size-dependent properties. The proposed magnetic separation method and simulation results have the significance for fundamental understanding of particle dynamic behavior and improving the separation efficiency.

Kinetic modeling of the formation and growth of inorganic nano-particles during pulverized coal char combustion in O 2/N 2 and O 2/CO 2 atmospheres

DOE PAGES

Shaddix, Christopher R.; Niu, Yanqing; Hui, Shi'en; ...

2016-08-01

In this formation of nano-particles during coal char combustion, the vaporization of inorganic components in char and the subsequent homogeneous particle nucleation, heterogeneous condensation, coagulation, and coalescence play decisive roles. Furthermore, conventional measurements cannot provide detailed information on the dynamics of nano-particle formation and evolution, In this study, a sophisticated intrinsic char kinetics model that considers ash effects (including ash film formation, ash dilution, and ash vaporization acting in tandem), both oxidation and gasification by CO 2 and H 2O, homogeneous particle nucleation, heterogeneous vapor condensation, coagulation, and and coalescence mechanisms is developed and used to compare the temporal evolutionmore » of the number and size of nano-particles during coal char particle combustion as a function of char particle size, ash content, and oxygen content in O 2/N 2 and O 2/CO 2 atmospheres .« less

Kinetic modeling of the formation and growth of inorganic nano-particles during pulverized coal char combustion in O 2/N 2 and O 2/CO 2 atmospheres

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

Shaddix, Christopher R.; Niu, Yanqing; Hui, Shi'en

In this formation of nano-particles during coal char combustion, the vaporization of inorganic components in char and the subsequent homogeneous particle nucleation, heterogeneous condensation, coagulation, and coalescence play decisive roles. Furthermore, conventional measurements cannot provide detailed information on the dynamics of nano-particle formation and evolution, In this study, a sophisticated intrinsic char kinetics model that considers ash effects (including ash film formation, ash dilution, and ash vaporization acting in tandem), both oxidation and gasification by CO 2 and H 2O, homogeneous particle nucleation, heterogeneous vapor condensation, coagulation, and and coalescence mechanisms is developed and used to compare the temporal evolutionmore » of the number and size of nano-particles during coal char particle combustion as a function of char particle size, ash content, and oxygen content in O 2/N 2 and O 2/CO 2 atmospheres .« less

Size effect of elemental selenium nanoparticles (Nano-Se) at supranutritional levels on selenium accumulation and glutathione S-transferase activity.

PubMed

Peng, Dungeng; Zhang, Jinsong; Liu, Qingliang; Taylor, Ethan Will

2007-10-01

-Se. Since both GST and small molecular weight selenocompounds accumulated in vivo are important intermediates for chemoprevention by Se, our results also suggest that Nano-Se should be most effective as a chemopreventive agent at smaller particle size.

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

Particle-size distribution modified effective medium theory and validation by magneto-dielectric Co-Ti substituted BaM ferrite composites

NASA Astrophysics Data System (ADS)

Li, Qifan; Chen, Yajie; Harris, Vincent G.

2018-05-01

This letter reports an extended effective medium theory (EMT) including particle-size distribution functions to maximize the magnetic properties of magneto-dielectric composites. It is experimentally verified by Co-Ti substituted barium ferrite (BaCoxTixFe12-2xO19)/wax composites with specifically designed particle-size distributions. In the form of an integral equation, the extended EMT formula essentially takes the size-dependent parameters of magnetic particle fillers into account. It predicts the effective permeability of magneto-dielectric composites with various particle-size distributions, indicating an optimal distribution for a population of magnetic particles. The improvement of the optimized effective permeability is significant concerning magnetic particles whose properties are strongly size dependent.

Characterization and Curing Kinetics of Epoxy/Silica Nano-Hybrids

PubMed Central

Yang, Cheng-Fu; Wang, Li-Fen; Wu, Song-Mao; Su, Chean-Cheng

2015-01-01

The sol-gel technique was used to prepare epoxy/silica nano-hybrids. The thermal characteristics, curing kinetics and structure of epoxy/silica nano-hybrids were studied using differential scanning calorimetry (DSC), 29Si nuclear magnetic resonance (NMR) and transmission electron microscopy (TEM). To improve the compatibility between the organic and inorganic phases, a coupling agent was used to modify the diglycidyl ether of bisphenol A (DGEBA) epoxy. The sol-gel technique enables the silica to be successfully incorporated into the network of the hybrids, increasing the thermal stability and improving the mechanical properties of the prepared epoxy/silica nano-hybrids. An autocatalytic mechanism of the epoxy/SiO2 nanocomposites was observed. The low reaction rate of epoxy in the nanocomposites is caused by the steric hindrance in the network of hybrids that arises from the consuming of epoxide group in the network of hybrids by the silica. In the nanocomposites, the nano-scale silica particles had an average size of approximately 35 nm, and the particles were well dispersed in the epoxy matrix, according to the TEM images. PMID:28793616

Controlling the size and magnetic properties of nano CoFe2O4 by microwave assisted co-precipitation method

NASA Astrophysics Data System (ADS)

Prabhakaran, T.; Mangalaraja, R. V.; Denardin, Juliano C.

2018-02-01

In this report, cobalt ferrite nanoparticles synthesized using microwave assisted co-precipitation method was reported. Efforts have been made to control the particles size, distribution, morphology and magnetic properties of cobalt ferrite nanoparticles by varying the concentration of NaOH solution and microwave irradiation time. It was observed that the rate of nucleation and crystal growth was influenced by the tuning parameters. In that way, the average crystallite size of single phase cobalt ferrite nanoparticles was controlled within 9-11 and 10-12 nm with an increase of base concentration and microwave irradiation time, respectively. A narrow size distribution of nearly spherical nanoparticles was achieved through the present procedure. A soft ferromagnetism at room temperature with the considerable saturation magnetization of 58.4 emu g-1 and coercivity of 262.7 Oe was obtained for the cobalt ferrites synthesized with 2.25 M of NaOH solution for 3 and 7 min of microwave irradiation time, respectively. The cobalt ferrite nanoparticles synthesized with a shorter reaction time of 3-7 min was found to be advantageous over other methods that involved conventional heating procedures and longer reaction time to achieve the better magnetic properties for the technological applications.

Properties of forced convection experimental with silicon carbide based nano-fluids

NASA Astrophysics Data System (ADS)

Soanker, Abhinay

With the advent of nanotechnology, many fields of Engineering and Science took a leap to the next level of advancements. The broad scope of nanotechnology initiated many studies of heat transfer and thermal engineering. Nano-fluids are one such technology and can be thought of as engineered colloidal fluids with nano-sized colloidal particles. There are different types of nano-fluids based on the colloidal particle and base fluids. Nano-fluids can primarily be categorized into metallic, ceramics, oxide, magnetic and carbon based. The present work is a part of investigation of the thermal and rheological properties of ceramic based nano-fluids. alpha-Silicon Carbide based nano-fluid with Ethylene Glycol and water mixture 50-50% volume concentration was used as the base fluid here. This work is divided into three parts; Theoretical modelling of effective thermal conductivity (ETC) of colloidal fluids, study of Thermal and Rheological properties of alpha-SiC nano-fluids, and determining the Heat Transfer properties of alpha-SiC nano-fluids. In the first part of this work, a theoretical model for effective thermal conductivity (ETC) of static based colloidal fluids was formulated based on the particle size, shape (spherical), thermal conductivity of base fluid and that of the colloidal particle, along with the particle distribution pattern in the fluid. A MATLAB program is generated to calculate the details of this model. The model is specifically derived for least and maximum ETC enhancement possible and thereby the lower and upper bounds was determined. In addition, ETC is also calculated for uniform colloidal distribution pattern. Effect of volume concentration on ETC was studied. No effect of particle size was observed for particle sizes below a certain value. Results of this model were compared with Wiener bounds and Hashin- Shtrikman bounds. The second part of this work is a study of thermal and rheological properties of alpha-Silicon Carbide based nano

Nano-catalysts with Magnetic Core: Sustainable Options for Greener Synthesis

EPA Science Inventory

Author’s perspective on nano-catalysts with magnetic core is summarized with recent work from his laboratory. Magnetically recyclable nano-catalysts and their use in benign media is an ideal blend for the development of sustainable methodologies in organic synthesis. Water or pol...

Effect of molecule-particle binding on the reduction in the mixed-frequency alternating current magnetic susceptibility of magnetic bio-reagents

NASA Astrophysics Data System (ADS)

Yang, C. C.; Yang, S. Y.; Chen, H. H.; Weng, W. L.; Horng, H. E.; Chieh, J. J.; Hong, C. Y.; Yang, H. C.

2012-07-01

By specifically bio-functionalizing magnetic nanoparticles, magnetic nanoparticles are able to label target bio-molecules. This property can be applied to quantitatively detect molecules invitro by measuring the related magnetic signals of nanoparticles bound with target molecules. One of the magnetic signals is the reduction in the mixed-frequency ac magnetic susceptibility of suspended magnetic nanoparticles due to the molecule-particle association. Many experimental results show empirically that the molecular-concentration dependent reduction in ac magnetic susceptibility follows the logistic function. In this study, it has been demonstrated that the logistic behavior is originated from the growth of particle sizes due to the molecule-particle association. The analytic relationship between the growth of particle sizes and the reduction in ac magnetic susceptibility is developed.

Dose limited reliability of quantitative annular dark field scanning transmission electron microscopy for nano-particle atom-counting.

PubMed

De Backer, A; Martinez, G T; MacArthur, K E; Jones, L; Béché, A; Nellist, P D; Van Aert, S

2015-04-01

Quantitative annular dark field scanning transmission electron microscopy (ADF STEM) has become a powerful technique to characterise nano-particles on an atomic scale. Because of their limited size and beam sensitivity, the atomic structure of such particles may become extremely challenging to determine. Therefore keeping the incoming electron dose to a minimum is important. However, this may reduce the reliability of quantitative ADF STEM which will here be demonstrated for nano-particle atom-counting. Based on experimental ADF STEM images of a real industrial catalyst, we discuss the limits for counting the number of atoms in a projected atomic column with single atom sensitivity. We diagnose these limits by combining a thorough statistical method and detailed image simulations. Copyright © 2014 Elsevier B.V. All rights reserved.

Thermal Stress Behavior of Micro- and Nano-Size Aluminum Films

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

Hanabusa, T.; Kusaka, K.; Nishida, M.

2008-03-17

In-situ observation of thermal stresses in thin films deposited on silicon substrate was made by X-ray and synchrotron radiation. Specimens prepared in this experiment were micro- and nano-size thin aluminum films with and without passivation film. The thickness of the film was 1 micrometer for micro-size films and 10, 20 and 50 nanometer for nano-size films. The stress measurement in micro-size films was made by X-ray radiation whereas the measurement of nano-size films was made by synchrotron radiation. Residual stress measurement revealed tensile stresses in all as-deposited films. Thermal stresses were measured in a series of heating- and cooling-stage. Thermalmore » stress behavior of micro-size films revealed hysteresis loop during a heating and cooling process. The width of a hysteresis loop was larger in passivated film that unpassivated film. No hysteresis loops were observed in nano-size films with SiO{sub 2} passivation. Strengthning mechanism in thin films was discussed on a passivation film and a film thickness.« less

Synthesis and characterization of porous CaCO3 micro/nano-particles

NASA Astrophysics Data System (ADS)

Achour, A.; Arman, A.; Islam, M.; Zavarian, A. A.; Basim Al-Zubaidi, A.; Szade, J.

2017-06-01

Porous CaCO3 particles, both micro and nano sized, were synthesized in a mixture of Ca(OH)2, hyaluronic acid (HA), glycine, NaOH and NaCl solution with supercritical carbon dioxide. The particles were characterized using X-Ray Diffraction (XRD), Fourier Transform Infrared (FTIR) spectroscope, Raman spectroscope (RS), X-ray photoelectron spectroscope (XPS) and scanning electron microscope techniques. All these techniques showed that the particles crystallize into only one CaCO3 structure, namely the vaterite phase. In addition, FTIR, RS and XPS indicated the presence of residual reactive species i.e. glycine, NaCl, and HA. The XRD results confirmed the presence of NaCl and γ-glycine, which is a crystalline material. Moreover, the HA seems to be mostly embedded in the bulk of the micro-particles. Such materials are promising for biomedical applications such as drug delivery.

How reliably can a material be classified as a nanomaterial? Available particle-sizing techniques at work

NASA Astrophysics Data System (ADS)

Babick, Frank; Mielke, Johannes; Wohlleben, Wendel; Weigel, Stefan; Hodoroaba, Vasile-Dan

2016-06-01

Currently established and projected regulatory frameworks require the classification of materials (whether nano or non-nano) as specified by respective definitions, most of which are based on the size of the constituent particles. This brings up the question if currently available techniques for particle size determination are capable of reliably classifying materials that potentially fall under these definitions. In this study, a wide variety of characterisation techniques, including counting, fractionating, and spectroscopic techniques, has been applied to the same set of materials under harmonised conditions. The selected materials comprised well-defined quality control materials (spherical, monodisperse) as well as industrial materials of complex shapes and considerable polydispersity. As a result, each technique could be evaluated with respect to the determination of the number-weighted median size. Recommendations on the most appropriate and efficient use of techniques for different types of material are given.

Evaluation of minimum quantity lubrication grinding with nano-particles and recent related patents.

PubMed

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

2013-06-01

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 supply system for the grinding fluid in nano-particle jet MQL, which produced MQL lubricant by adding solid nano-particles in degradable grinding fluid. The MQL supply device turns the lubricant to the pulse drops with fixed pressure, unchanged pulse frequency and the same drop diameter. The drops will be produced and injected in the grinding zone in the form of jet flow under high pressure gas and air seal. As people become increasingly demanding on our environment, minimum quantity lubrication has been widely used in the grinding and processing. Yet, it presents the defect of insufficient cooling performance, which confines its development. To improve the heat transfer efficiency of MQL, nano-particles of a certain mass fraction can be added in the minimum quantity of lubricant oil, which concomitantly will improve the lubrication effects in the processing. In this study, the grinding experiment corroborated the effect of nano-particles in surface grinding. In addition, compared with other forms of lubrication, the results presented that the grinding force, the friction coefficient and specific grinding energy of MQL grinding have been significantly weakened, while G ratio greatly rose. These are attributed to the friction oil-film with excellent anti-friction and anti-wear performance, which is generated nano-particles at the wheel/workpiece interface. In this research, the cooling performance of nano-particle jet MQL was analyzed. Based on tests and experiments, the surface temperature was assayed from different methods, including flood lubricating oil, dry grinding, MQL grinding and nano-particle jet MQL grinding. Because of the outstanding heat transfer

Nano- and Microparticles in Welding Aerosol: Granulometric Analysis

NASA Astrophysics Data System (ADS)

Kirichenko, K. Yu.; Drozd, V. A.; Chaika, V. V.; Gridasov, A. V.; Kholodov, A. S.; Golokhvast, K. S.

The paper presents the first results of the study of the size of particles appearing in the welding process by means of laser granulometry. It is shown that welding aerosol is the source of nano-and micro-sized particles extremely dangerous for human and animal health. Particle size distribution in the microrange was from 1 to 10 μm and up to 100%. It is shown that in 9 cases out of 28 with the use of various welding modes, welding rods and components the emission of aerosol with nano-sized particles (from 45.5% to 99.4%) is observed.

Fiber Bragg grating filter using evaporated induced self assembly of silica nano particles

NASA Astrophysics Data System (ADS)

Hammarling, Krister; Zhang, Renyung; Manuilskiy, Anatoliy; Nilsson, Hans-Erik

2014-03-01

In the present work we conduct a study of fiber filters produced by evaporation of silica particles upon a MM-fiber core. A band filter was designed and theoretically verified using a 2D Comsol simulation model of a 3D problem, and calculated in the frequency domain in respect to refractive index. The fiber filters were fabricated by stripping and chemically etching the middle part of an MM-fiber until the core was exposed. A mono layer of silica nano particles were evaporated on the core using an Evaporation Induced Self-Assembly (EISA) method. The experimental results indicated a broader bandwidth than indicated by the simulations which can be explained by the mismatch in the particle size distributions, uneven particle packing and finally by effects from multiple mode angles. Thus, there are several closely connected Bragg wavelengths that build up the broader bandwidth. The experimental part shows that it is possible by narrowing the particle size distributing and better control of the particle packing, the filter effectiveness can be greatly improved.

Simple preparation of magnetic field-responsive structural colored Janus particles.

PubMed

Teshima, Midori; Seki, Takahiro; Takeoka, Yukikazu

2018-03-08

We established a simple method for preparing Janus particles displaying different structural colors using submicron-sized fine silica particles and magnetic nanoparticles composed of Fe 3 O 4 . A w/o emulsion is prepared by vortex-stirring a mixed aqueous solution of suspended fine silica particles and magnetic nanoparticles and of hexadecane containing an emulsifier. Subsequent drying of the emulsion on a hot plate using a magnetic stirrer provides a polydisperse particle aggregate displaying two different structural colors according to the ratio of the amount of fine silica particles to the amount of magnetic nanoparticles. This polydisperse particle aggregate can be converted into monodisperse particles simply by using a sieve made of stainless steel. In the presence of a magnet, the monodisperse Janus particles can change their orientation and can switch between two different structural colors.

Nano/microstructure and optical properties of ZnO particles precipitated from zinc acetylacetonate

NASA Astrophysics Data System (ADS)

Petrović, Željka; Ristić, Mira; Musić, Svetozar; Fabián, Martin

2015-06-01

The influence of experimental conditions on the nano/microstructure and optical properties of ZnO particles produced by rapid hydrolysis of zinc acetylacetonate, followed by aging of the precipitation system at 160 °C, was investigated. Samples were characterized by XRD, FE scanning electron microscopy (FE-SEM), FT-IR, UV/Vis/NIR and photoluminescence (PL) spectroscopies. XRD patterns of all samples were assigned to the hexagonal ZnO phase (wurtzite-type), as well as the corresponding FT-IR spectra. FE-SEM inspection showed a high dependence of the ZnO nano/microstructure on the chemical composition of the reaction mixture and autoclaving time after the rapid hydrolysis of zinc acetylacetonate. Microstructural differences were noticed between C2H5OH/H2O and H2O media, as well as under the influence of NH4OH addition. Measurements of nanocrystallite sizes showed no significant preferential orientation in the (1 0 0) and (0 0 2) directions relative to the (1 0 1) and (1 1 0) directions. Somewhat smaller crystallite sizes were noticed for ZnO samples synthesized by adding the NH4OH solution. Dissolution/recrystallization of ZnO particles played an important role in the formation of different ZnO nano/microstructures. The band gap values for prepared ZnO samples were calculated on the basis of recorded UV/Vis spectra. PL spectra were recorded for ZnO samples in powder form and their suspensions in pure ethanol. Noticed differences are discussed.

Synthesis, structural and magnetic properties of Mg0.6Zn0.4CrxFe2-xO4 (0.0 ≤ x ≤ 2.0) nano ferrite

NASA Astrophysics Data System (ADS)

Verma, R.; Kane, S. N.; Raghuvanshi, S.; Satalkar, M.; Modak, S. S.; Mazaleyrat, F.

2018-05-01

Present study reports, effect on structural, magnetic properties of Cr doped Mg-Zn nano-ferrite: Mg0.6Zn0.4CrxFe2-xO4 (0.0≤ x≤2.0), synthesized by sol-gel auto combustion method. X-ray diffraction (XRD), vibrating sample magnetometer (VSM), scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS) techniques were utilized to monitor the effect of Cr substitution on structural, magnetic properties, and correlation between them. XRD confirms the formation of single phase spinel nano ferrite with particle size ranging between 3.9 - 40.5 nm, whereas EDS confirms the formation of the estimated ferrite composition. Distribution of Mg, Zn, Cr, Fe cations on tetrahedral (A), octahedral (B) site show mixed spinel structure. Increase of Cr content leads to increase of specific surface area (4.35 - 28.28 m2/g), decrease of experimental saturation magnetization at 300 K (varies between 0.57 - 40.95 Am2/kg), and theoretical magnetization at 0 K (range between 13.37 - 56.77 Am2/kg). Observed changes in coercivity values reflect soft magnetic nature of the studied ferrites.

Enhanced photo-response of porous silicon photo-detectors by embeddingTitanium-dioxide nano-particles

NASA Astrophysics Data System (ADS)

Ali, Hiba M.; Makki, Sameer A.; Abd, Ahmed N.

2018-05-01

Porous silicon (n-PS) films can be prepared by photoelectochemical etching (PECE) Silicon chips n - types with 15 (mA / cm2), in 15 minutes etching time on the fabrication nano-sized pore arrangement. By using X-ray diffraction measurement and atomic power microscopy characteristics (AFM), PS was investigated. It was also evaluated the crystallites size from (XRD) for the PS nanoscale. The atomic force microscopy confirmed the nano-metric size chemical fictionalization through the electrochemical etching that was shown on the PS surface chemical composition. The atomic power microscopy checks showed the roughness of the silicon surface. It is also notified (TiO2) preparation nano-particles that were prepared by pulse laser eradication in ethanol (PLAL) technique through irradiation with a Nd:YAG laser pulses TiO2 target that is sunk in methanol using 400 mJ of laser energy. It has been studied the structural, optical and morphological of TiO2NPs. It has been detected that through XRD measurement, (TiO2) NPs have been Tetragonal crystal structure. While with AFM measurements, it has been realized that the synthesized TiO2 particles are spherical with an average particle size in the (82 nm) range. It has been determined that the energy band gap of TiO2 NPs from optical properties and set to be in (5eV) range.The transmittance and reflectance spectra have determined the TiO2 NPs optical constants. It was reported the effectiveness of TiO2 NPs expansion on the PS Photodetector properties which exposes the benefits in (Al/PS/Si/Al). The built-in tension values depend on the etching time current density and laser flounce. Al/TiO2/PS/Si/Al photo-detector heterojunction have two response peaks that are situated at 350 nm and (700 -800nm) with max sensitivity ≈ 0.7 A/W. The maximum given detectivity is 9.38at ≈ 780 nm wavelength.

Nano-soldering of magnetically aligned three-dimensional nanowire networks.

PubMed

Gao, Fan; Gu, Zhiyong

2010-03-19

It is extremely challenging to fabricate 3D integrated nanostructures and hybrid nanoelectronic devices. In this paper, we report a simple and efficient method to simultaneously assemble and solder nanowires into ordered 3D and electrically conductive nanowire networks. Nano-solders such as tin were fabricated onto both ends of multi-segmented nanowires by a template-assisted electrodeposition method. These nanowires were then self-assembled and soldered into large-scale 3D network structures by magnetic field assisted assembly in a liquid medium with a high boiling point. The formation of junctions/interconnects between the nanowires and the scale of the assembly were dependent on the solder reflow temperature and the strength of the magnetic field. The size of the assembled nanowire networks ranged from tens of microns to millimeters. The electrical characteristics of the 3D nanowire networks were measured by regular current-voltage (I-V) measurements using a probe station with micropositioners. Nano-solders, when combined with assembling techniques, can be used to efficiently connect and join nanowires with low contact resistance, which are very well suited for sensor integration as well as nanoelectronic device fabrication.

Nano-sized Adsorbate Structure Formation in Anisotropic Multilayer System

NASA Astrophysics Data System (ADS)

Kharchenko, Vasyl O.; Kharchenko, Dmitrii O.; Yanovsky, Vladimir V.

2017-05-01

In this article, we study dynamics of adsorbate island formation in a model plasma-condensate system numerically. We derive the generalized reaction-diffusion model for adsorptive multilayer system by taking into account anisotropy in transfer of adatoms between neighbor layers induced by electric field. It will be found that with an increase in the electric field strength, a structural transformation from nano-holes inside adsorbate matrix toward separated nano-sized adsorbate islands on a substrate is realized. Dynamics of adsorbate island sizes and corresponding distributions are analyzed in detail. This study provides an insight into details of self-organization of adatoms into nano-sized adsorbate islands in anisotropic multilayer plasma-condensate systems.

Comparative study of structural and magnetic properties of nano-crystalline Li 0.5Fe 2.5O 4 prepared by various methods

NASA Astrophysics Data System (ADS)

Verma, Vivek; Pandey, Vibhav; Singh, Sukhveer; Aloysius, R. P.; Annapoorni, S.; Kotanala, R. K.

2009-08-01

Lithium ferrite has been considered as one of the highly strategic magnetic material. Nano-crystalline Li 0.5Fe 2.5O 4 was prepared by four different techniques and characterized by X-ray diffraction, vibrating sample magnetometer (VSM), transmission electron microscope (TEM) and Fourier transform infrareds (FTIR). The effect of annealing temperature (700, 900 and 1050 °C) on microstructure has been correlated to the magnetic properties. From X-ray diffraction patterns, it is confirmed that the pure phase of lithium ferrite began to form at 900 °C annealing. The particle size of as-prepared lithium ferrite was observed around 40, 31, 22 and 93 nm prepared by flash combustion, sol-gel, citrate precursor and standard ceramic technique, respectively. Lithium ferrite prepared by citrate precursor method shows a maximum saturation magnetization 67.6 emu/g at 5 KOe.

Optical spins and nano-antenna array for magnetic therapy.

PubMed

Thammawongsa, N; Mitatha, S; Yupapin, P P

2013-09-01

Magnetic therapy is an alternative medicine practice involving the use of magnetic fields subjected to certain parts of the body and stimulates healing from a range of health problems. In this paper, an embedded nano-antenna system using the optical spins generated from a particular configuration of microrings (PANDA) is proposed. The orthogonal solitons pairs corresponding to the left-hand and right-hand optical solitons (photons) produced from dark-bright soliton conversion can be simultaneously detected within the system at the output ports. Two possible spin states which are assigned as angular momentum of either +ħ or -ħ will be absorbed by an object whenever this set of orthogonal solitons is imparted to the object. Magnetic moments could indeed arise from the intrinsic property of spins. By controlling some important parameters of the system such as soliton input power, coupling coefficients and sizes of rings, output signals from microring resonator system can be tuned and optimized to be used as magnetic therapy array.

Atomic layer deposition of titanium oxide films on As-synthesized magnetic Ni particles: Magnetic and safety properties

NASA Astrophysics Data System (ADS)

Uudeküll, Peep; Kozlova, Jekaterina; Mändar, Hugo; Link, Joosep; Sihtmäe, Mariliis; Käosaar, Sandra; Blinova, Irina; Kasemets, Kaja; Kahru, Anne; Stern, Raivo; Tätte, Tanel; Kukli, Kaupo; Tamm, Aile

2017-05-01

Spherical nickel particles with size in the range of 100-400 nm were synthesized by non-aqueous liquid phase benzyl alcohol method. Being developed for magnetically guided biomedical applications, the particles were coated by conformal and antimicrobial thin titanium oxide films by atomic layer deposition. The particles retained their size and crystal structure after the deposition of oxide films. The sensitivity of the coated particles to external magnetic fields was increased compared to that of the uncoated powder. Preliminary toxicological investigations on microbial cells and small aquatic crustaceans revealed non-toxic nature of the synthesized particles.

Label-Free Alignment of Nonmagnetic Particles in a Small Uniform Magnetic Field.

PubMed

Wang, Zhaomeng; Wang, Ying; Wu, Rui Ge; Wang, Z P; Ramanujan, R V

2018-01-01

Label-free manipulation of biological entities can minimize damage, increase viability and improve efficiency of subsequent analysis. Understanding the mechanism of interaction between magnetic and nonmagnetic particles in an inverse ferrofluid can provide a mechanism of label-free manipulation of such entities in a uniform magnetic field. The magnetic force, induced by relative magnetic susceptibility difference between nonmagnetic particles and surrounding magnetic particles as well as particle-particle interaction were studied. Label-free alignment of nonmagnetic particles can be achieved by higher magnetic field strength (Ba), smaller particle spacing (R), larger particle size (rp1), and higher relative magnetic permeability difference between particle and the surrounding fluid (Rμr). Rμr can be used to predict the direction of the magnetic force between both magnetic and nonmagnetic particles. A sandwich structure, containing alternate layers of magnetic and nonmagnetic particle chains, was studied. This work can be used for manipulation of nonmagnetic particles in lab-on-a-chip applications.

Antibacterial performance of nano polypropylene filter media containing nano-TiO2 and clay particles

NASA Astrophysics Data System (ADS)

Shafiee, Sara; Zarrebini, Mohammad; Naghashzargar, Elham; Semnani, Dariush

2015-10-01

Disinfection and elimination of pathogenic microorganisms from liquid can be achieved by filtration process using antibacterial filter media. The advent of nanotechnology has facilitated the introduction of membranes consisting of nano-fiber in filtration operations. The melt electro-spun fibers due to their extremely small diameters are used in the production of this particular filtration medium. In this work, antibacterial polypropylene filter medium containing clay particles and nano-TiO2 were made using melt electro-spun technology. Antibacterial performance of polypropylene nano-filters was evaluated using E. coli bacteria. Additionally, filtration efficiency of the samples in terms fiber diameter, filter porosity, and fiber distribution using image processing technique was determined. Air permeability and dust aerosol tests were conducted to establish the suitability of the samples as a filter medium. It was concluded that as far as antibacterial property is concerned, nano-fibers filter media containing clay particles are preferential to similar media containing TiO2 nanoparticles.

Genotoxicity assessment of magnetic iron oxide nanoparticles with different particle sizes and surface coatings

NASA Astrophysics Data System (ADS)

Liu, Yanping; Xia, Qiyue; Liu, Ying; Zhang, Shuyang; Cheng, Feng; Zhong, Zhihui; Wang, Li; Li, Hongxia; Xiao, Kai

2014-10-01

Magnetic iron oxide nanoparticles (IONPs) have been widely used for various biomedical applications such as magnetic resonance imaging and drug delivery. However, their potential toxic effects, including genotoxicity, need to be thoroughly understood. In the present study, the genotoxicity of IONPs with different particle sizes (10, 30 nm) and surface coatings (PEG, PEI) were assessed using three standard genotoxicity assays, the Salmonella typhimurium reverse mutation assay (Ames test), the in vitro mammalian chromosome aberration test, and the in vivo micronucleus assay. In the Ames test, SMG-10 (PEG coating, 10 nm) showed a positive mutagenic response in all the five test bacterial strains with and without metabolic activation, whereas SEI-10 (PEI coating, 10 nm) showed no mutagenesis in all tester strains regardless of metabolic activation. SMG-30 (PEG coating, 30 nm) was not mutagenic in the absence of metabolic activation, and became mutagenic in the presence of metabolic activation. In the chromosomal aberration test, no increase in the incidence of chromosomal aberrations was observed for all three IONPs. In the in vivo micronucleus test, there was no evidence of increased micronuclei frequencies for all three IONPs, indicating that they were not clastogenic in vivo. Taken together, our results demonstrated that IONPs with PEG coating exhibited mutagenic activity without chromosomal and clastogenic abnormalities, and smaller IONPs (SMG-10) had stronger mutagenic potential than larger ones (SMG-30); whereas, IONPs with SEI coating (SEI-10) were not genotoxic in all three standard genotoxicity assays. This suggests that the mutagenicity of IONPs depends on their particle size and surface coating.

Post-adsorption process of Yb phosphate nano-particle formation by Saccharomyces cerevisiae

NASA Astrophysics Data System (ADS)

Jiang, MingYu; Ohnuki, Toshihiko; Tanaka, Kazuya; Kozai, Naofumi; Kamiishi, Eigo; Utsunomiya, Satoshi

2012-09-01

In this study, we have investigated the post-adsorption process of ytterbium (Yb) phosphate nano-particle formation by Saccharomyces cerevisiae (yeast). The yeast grown in P-rich medium were exposed to 1.44 × 10-4 mol/L Yb(III) solution for 2-120 h, and 2 months at 25 ± 1 °C at an initial pH of 3, 4, or 5, respectively. Ytterbium concentrations in solutions decreased as a function of exposure time. Field-emission scanning electron microscopy equipped with energy-dispersive X-ray spectroscopy (FESEM), transmission electron microscopy (TEM), and synchrotron-based extended X-ray absorption fine structure (EXAFS) analyses revealed that nano-sized blocky Yb phosphate with an amorphous phase formed on the yeast cells surfaces in the solutions with Yb. These nano-sized precipitates that formed on the cell surfaces remained stable even after 2 months of exposure at 25 ± 1 °C around neutral pHs. The EXAFS data revealed that the chemical state of the accumulated Yb on the cell surfaces changed from the adsorption on both phosphate and carboxyl sites at 30 min to Yb phosphate precipitates at 5 days, indicating the Yb-phosphate precipitation as a major post-adsorption process. In addition, the precipitation of Yb phosphate occurred on cell surfaces during 7 days of exposure in Yb-free solution after 2 h of exposure (short-term Yb adsorption) in Yb solution. These results suggest that the released P from the inside of yeast cells reacted with adsorbed Yb on cell surfaces, resulting in the formation of Yb precipitates, even though no P was added to the exposure solution. In an abiotic system, the EXAFS data showed that the speciation of sorbed Yb on the reference materials, carboxymethyl cellulose and Ln resin, did not change even when the Yb was exposed to P solution, without forming Yb phosphate precipitates. This result strongly suggests that the cell surface of the yeast plays an important role in the Yb-phosphate precipitation process, not only as a carrier of the

Support for the initial attachment, growth and differentiation of MG-63 cells: a comparison between nano-size hydroxyapatite and micro-size hydroxyapatite in composites

PubMed Central

Filová, Elena; Suchý, Tomáš; Sucharda, Zbyněk; Šupová, Monika; Žaloudková, Margit; Balík, Karel; Lisá, Věra; Šlouf, Miroslav; Bačáková, Lucie

2014-01-01

Hydroxyapatite (HA) is considered to be a bioactive material that favorably influences the adhesion, growth, and osteogenic differentiation of osteoblasts. To optimize the cell response on the hydroxyapatite composite, it is desirable to assess the optimum concentration and also the optimum particle size. The aim of our study was to prepare composite materials made of polydimethylsiloxane, polyamide, and nano-sized (N) or micro-sized (M) HA, with an HA content of 0%, 2%, 5%, 10%, 15%, 20%, 25% (v/v) (referred to as N0–N25 or M0–M25), and to evaluate them in vitro in cultures with human osteoblast-like MG-63 cells. For clinical applications, fast osseointegration of the implant into the bone is essential. We observed the greatest initial cell adhesion on composites M10 and N5. Nano-sized HA supported cell growth, especially during the first 3 days of culture. On composites with micro-size HA (2%–15%), MG-63 cells reached the highest densities on day 7. Samples M20 and M25, however, were toxic for MG-63 cells, although these composites supported the production of osteocalcin in these cells. On N2, a higher concentration of osteopontin was found in MG-63 cells. For biomedical applications, the concentration range of 5%–15% (v/v) nano-size or micro-size HA seems to be optimum. PMID:25125978

Effect of relative weight group change on nuclear magnetic resonance spectroscopy derived lipoprotein particle size and concentrations among adolescents.

PubMed

Jago, Russell; Drews, Kimberly L; Otvos, James D; Foster, Gary D; Marcus, Marsha D; Buse, John B; Mietus-Snyder, Michele; Willi, Steven M

2014-05-01

To examine whether longitudinal changes in relative weight category (as indicated by change in body mass index [BMI] classification group) were associated with changes in nuclear magnetic resonance (NMR)-derived lipoprotein particles among US youth. Secondary analysis of data from a clustered randomized controlled trial. BMI and fasting blood samples were obtained from 2069 participants at the start of the 6th grade and end of the 8th grade. BMI was categorized as normal weight, overweight, or obese at both time points. Lipoprotein particle profiles were measured with NMR spectroscopy at both time points. Regression models were used to examine changes in relative weight group and change in lipoprotein variables. A total of 38% of participants changed relative weight category (BMI group) during the 2.5-year study period. Low-density lipoprotein (LDL) cholesterol and non-high-density lipoprotein (HDL) cholesterol decreased almost universally, but more with improved BMI category. There were adverse effects on LDL size and total LDL particles, HDL size, and cholesterol for participants who remained obese or whose relative weight group worsened. Changes in relative category had no impact on HDL particles. Improvement in relative weight group from 6th to 8th grade was associated with favorable changes in non-HDL cholesterol, very low-density lipoprotein size, LDL size, HDL size, and LDL particles but had no effect on HDL particles. Findings indicate that an improvement in relative weight group between 6th and 8th grade had an effect on NMR-derived particles sizes and concentrations among a large group of adolescents, which overrepresented low-income minorities. Copyright © 2014 Elsevier Inc. All rights reserved.

Effect of nano/micro-Ag compound particles on the bio-corrosion, antibacterial properties and cell biocompatibility of Ti-Ag alloys.

PubMed

Chen, Mian; Yang, Lei; Zhang, Lan; Han, Yong; Lu, Zheng; Qin, Gaowu; Zhang, Erlin

2017-06-01

In this research, Ti-Ag alloys were prepared by powder metallurgy, casting and heat treatment method in order to investigate the effect of Ag compound particles on the bio-corrosion, the antibacterial property and the cell biocompatibility. Ti-Ag alloys with different sizes of Ag or Ag-compounds particles were successfully prepared: small amount of submicro-scale (100nm) Ti 2 Ag precipitates with solid solution state of Ag, large amount of nano-scale (20-30nm) Ti 2 Ag precipitates with small amount of solid solution state of Ag and micro-scale lamellar Ti 2 Ag phases, and complete solid solution state of Ag. The mechanical tests indicated that both nano/micro-scale Ti 2 Ag phases had a strong dispersion strengthening ability and Ag had a high solid solution strengthening ability. Electrochemical results shown the Ag content and the size of Ag particles had a limited influence on the bio-corrosion resistance although nano-scale Ti 2 Ag precipitates slightly improved corrosion resistance. It was demonstrated that the nano Ag compounds precipitates have a significant influence on the antibacterial properties of Ti-Ag alloys but no effect on the cell biocompatibility. It was thought that both Ag ions release and Ti 2 Ag precipitates contributed to the antibacterial ability, in which nano-scale and homogeneously distributed Ti 2 Ag phases would play a key role in antibacterial process. Copyright © 2017 Elsevier B.V. All rights reserved.

Physical properties of elongated magnetic particles: magnetization and friction coefficient anisotropies.

PubMed

Vereda, Fernando; de Vicente, Juan; Hidalgo-Alvarez, Roque

2009-06-02

Anisotropy counts: A brief review of the main physical properties of elongated magnetic particles (EMPs) is presented. The most important characteristic of an EMP is the additional contribution of shape anisotropy to the total anisotropy energy of the particle, when compared to spherical magnetic particles. The electron micrograph shows Ni-ferrite microrods fabricated by the authors.We present an overview of the main physical properties of elongated magnetic particles (EMPs), including some of their more relevant properties in suspension. When compared to a spherical magnetic particle, the most important characteristic of an EMP is an additional contribution of shape anisotropy to the total anisotropy energy of the particle. Increasing aspect ratios also lead to an increase in both the critical single-domain size of a magnetic particle and its resistance to thermally activated spontaneous reversal of the magnetization. For single-domain EMPs, magnetization reversal occurs primarily by one of two modes, coherent rotation or curling, the latter being facilitated by larger aspect ratios. When EMPs are used to prepare colloidal suspensions, other physical properties come into play, such as their anisotropic friction coefficient and the consequent enhanced torque they experience in a shear flow, their tendency to align in the direction of an external field, to form less dense sediments and to entangle into more intricate aggregates. From a more practical point of view, EMPs are discussed in connection with two interesting types of magnetic colloids: magnetorheological fluids and suspensions for magnetic hyperthermia. Advances reported in the literature regarding the use of EMPs in these two systems are included. In the final section, we present a summary of the most relevant methods documented in the literature for the fabrication of EMPs, together with a list of the most common ferromagnetic materials that have been synthesized in the form of EMPs.

Characteristics of nano-sized yttria powder synthesized by a polyvinyl alcohol solution route at low temperature.

PubMed

Lee, Sang-Jin; Jung, Choong-Hwan

2012-01-01

Nano-sized yttria (Y2O3) powders were successfully synthesized at a low temperature of 400 degrees C by a simple polymer solution route. PVA polymer, as an organic carrier, contributed to an atom-scale homogeneous precursor gel and it resulted in fully crystallized, nano-sized yttria powder with high specific surface area through the low temperature calcination. In this process, the content of PVA, calcination temperature and heating time affected the microstructure and crystallization behavior of the powders. The development of crystalline phase and the final particle size were strongly dependant on the oxidation reaction from the polymer burn-out step and the PVA content. In this paper, the PVA solution technique for the fabrication of nano-sized yttria powders is introduced. The effects of PVA content and holding time on the powder morphology and powder specific surface area are also studied. The characterization of the synthesized powders is examined by using XRD, DTA/TG, SEM, TEM and nitrogen gas adsorption. The yttria powder synthesized from the PVA content of 3:1 ratio and calcined at 400 degrees C had a crystallite size of about 20 nm or less with a high surface areas of 93.95-120.76 m2 g(-1).

Oxidative stress, cytoxicity, and cell mortality induced by nano-sized lead in aqueous suspensions.

PubMed

Cornejo-Garrido, Hilda; Kibanova, Daria; Nieto-Camacho, Antonio; Guzmán, José; Ramírez-Apan, Teresa; Fernández-Lomelín, Pilar; Garduño, Maria Laura; Cervini-Silva, Javiera

2011-09-01

This paper reports on the effect of aqueous and nano-particulated Pb on oxidative stress (lipid peroxidation), cytoxicity, and cell mortality. As determined by the Thiobarbituric Acid Reactive Substances (TBARS) method, only 6h after incubation aqueous suspensions bearing nano-sized PbO(2), soluble Pb(II), and brain-homogenate only suspensions, were determined to contain as much as ca. 7, 5, and 1 nmol TBARS mg protein(-1), respectively. Exposure of human cells (central nervous system, prostate, leukemia, colon, breast, lung cells) to nano-PbO(2) led to cell-growth inhibition values (%) ca. ≤18.7%. Finally, as estimated by the Artemia salina test, cell mortality values were found to show high-survival larvae rates. Microscopic observations revealed that Pb particles were swallowed, but caused no mortality, however. Copyright © 2011 Elsevier Ltd. All rights reserved.

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.

The use of nano-sized eggshell powder for calcium fortification of cow?s and buffalo?s milk yogurts.

PubMed

El-Shibiny, Safinaze; El-Gawad, Mona Abd El-Kader Mohamed Abd; Assem, Fayza Mohamed; El-Sayed, Samah Mosbah

2018-01-01

Calcium is an essential element for the growth, activity, and maintenance of the human body. Eggshells are a waste product which has received growing interest as a cheap and effective source of dietary calcium. Yogurt is a food which can be fortified with functional additives, including calcium. The aim of this study was to produce yogurt with a high calcium content by fortification with nano-sized eggshell powder (nano-ESP). Nano-sized ESP was prepared from pre-boiled and dried eggshell, using a ball mill. Yogurt was prepared from cow’s milk supplemented with 3% skimmed milk powder, and from buffalo’s milk fortified with 0.1, 0.2 and 0.3% and 0.1, 0.3 and 0.5% nano-ESP respectively. Electron microscopic transmission showed that the powder consisted of nano-sized crystalline struc- tures (~10 nm). Laser scattering showed that particles followed a normal distribution pattern with z-average of 590.5 nm, and had negative zeta-potential of –9.33 ±4.2 mV. Results regarding changes in yogurt composi- tion, acid development, calcium distribution, biochemical changes, textural parameters and sensory attributes have been presented and discussed. The addition of up to 0.3% nano-ESP made cow and buffalo high-calcium yogurts with an acceptable composition and quality. High-calcium yogurt may offer better health benefits, such as combating osteoporosis.

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.

Magnetic properties of nano-multiferroic materials

NASA Astrophysics Data System (ADS)

Ramam, Koduri; Diwakar, Bhagavathula S.; Varaprasad, Kokkarachedu; Swaminadham, Veluri; Reddy, Venu

2017-11-01

Latent magnetization in the multiferroics can be achieved via the structural distortion with respect to particle size and destroying the spiral spin structure, which plays the vital role in high-performance applications. In this investigation, multifunctional single phase Bi1-xLaxFe1-yCoyO3 nanomaterials were synthesized by co-precipitation technique. The chemical composition, phase genesis, morphology and thermal characteristics of the Bi1-xLaxFe1-yCoyO3 were studied by FTIR, XRD, SEM/EDS, TEM and TGA. XRD studies confirmed single phase distorted rhombohedral structure in Bi1-xLaxFe1-yCoyO3. The novelty in magnetic behavior of the Bi0.85La0.15Fe0.75Co0.25O3 multiferroic at room temperature showed both ferro and anti-ferromagnetic nature with higher order remanent magnetization among other nanocomposites in this study. This magnetic anomaly in Bi0.85La0.15Fe0.75Co0.25O3 is due to doping and size effects on the crystal structure that leads to spin-orbit interactions. Besides, Bi0.85La0.15Fe0.75Co0.25O3 integrated graphene oxide (GO) nanocomposite has shown the change in the magnetic hysteresis that indicates the effect of the semiconducting behavior of GO on the ordered magnetic moments in the multiferroic. This kind of magnetic anomaly could form advanced multiferroic devices.

Influence of Shell Thickness on the Colloidal Stability of Magnetic Core-Shell Particle Suspensions.

PubMed

Neville, Frances; Moreno-Atanasio, Roberto

2018-01-01

We present a Discrete Element study of the behavior of magnetic core-shell particles in which the properties of the core and the shell are explicitly defined. Particle cores were considered to be made of pure iron and thus possessed ferromagnetic properties, while particle shells were considered to be made of silica. Core sizes ranged between 0.5 and 4.0 μm with the actual particle size of the core-shell particles in the range between 0.6 and 21 μm. The magnetic cores were considered to have a magnetization of one tenth of the saturation magnetization of iron. This study aimed to understand how the thickness of the shell hinders the formation of particle chains. Chain formation was studied with different shell thicknesses and particle sizes in the presence and absence of an electrical double layer force in order to investigate the effect of surface charge density on the magnetic core-shell particle interactions. For core sizes of 0.5 and 4.0 μm the relative shell thicknesses needed to hinder the aggregation process were approximately 0.4 and 0.6 respectively, indicating that larger core sizes are detrimental to be used in applications in which no flocculation is needed. In addition, the presence of an electrical double layer, for values of surface charge density of less than 20 mC/m 2 , could stop the contact between particles without hindering their vertical alignment. Only when the shell thickness was considerably larger, was the electrical double layer able to contribute to the full disruption of the magnetic flocculation process.

Effect of particle size and percentages of Boron carbide on the thermal neutron radiation shielding properties of HDPE/B4C composite: Experimental and simulation studies

NASA Astrophysics Data System (ADS)

Soltani, Zahra; Beigzadeh, Amirmohammad; Ziaie, Farhood; Asadi, Eskandar

2016-10-01

In this paper the effects of particle size and weight percentage of the reinforcement phase on the absorption ability of thermal neutron by HDPE/B4C composites were investigated by means of Monte-Carlo simulation method using MCNP code and experimental studies. The composite samples were prepared using the HDPE filled with different weight percentages of Boron carbide powder in the form of micro and nano particles. Micro and nano composite were prepared under the similar mixing and moulding processes. The samples were subjected to thermal neutron radiation. Neutron shielding efficiency in terms of the neutron transmission fractions of the composite samples were investigated and compared with simulation results. According to the simulation results, the particle size of the radiation shielding material has an important role on the shielding efficiency. By decreasing the particle size of shielding material in each weight percentages of the reinforcement phase, better radiation shielding properties were obtained. It seems that, decreasing the particle size and homogeneous distribution of nano forms of B4C particles, cause to increase the collision probability between the incident thermal neutron and the shielding material which consequently improve the radiation shielding properties. So, this result, propose the feasibility of nano composite as shielding material to have a high performance shielding characteristic, low weight and low thick shielding along with economical benefit.

Particle size effect in porous film electrodes of ligand-modified graphene for enhanced supercapacitor performance

DOE PAGES

Jang, Gyoung Gug; Song, Bo; Moon, Kyoung-sik; ...

2017-04-17

Graphene-based electrodes for high performance supercapacitors are developed by taking advantage of particle size control, large mass loading, and surface functionalization of reduced graphene oxide (rGO) sheets. Two controlled sizes of graphene sheets (100 nm vs. 45 μm average lateral dimensions) were prepared to study two-electrode system performance. The nano-size graphenes led to the formation of mesoporous films, resulting in higher capacitance, better capacitance retension and lower equivalent series resistance (ESR), indicating better surface usability for diffusion and accessibility of electrolyte ions by shortening transport paths (compared with horizontally stacked films from micro-sized graphenes). For studies using an aqueous electrolyte,more » the maximum specific capacitance of nano-rGO film was 302 F/g (at 1 A/g with 4.3 mg/cm 2 of mass loading), which was ~2.4 times higher than micro-rGO film, and achieved a ~67% reduced ESR. With an organic electrolyte, the nano-rGO delivered ~4.2 times higher capacitance (115 F/g at 2 A/g with 4.3 mg/cm 2), 4.0 times lower IR drops, and an order-of-magnitude lower charge-transfer resistance with an energy density of 18.7 Wh/kg. Finally, the results of this work indicate that the size control of graphene sheet particles for film deposit electrodes can be a simple but effective approach to improve supercapacitor performance.« less

Particle size effect in porous film electrodes of ligand-modified graphene for enhanced supercapacitor performance

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

Jang, Gyoung Gug; Song, Bo; Moon, Kyoung-sik

Graphene-based electrodes for high performance supercapacitors are developed by taking advantage of particle size control, large mass loading, and surface functionalization of reduced graphene oxide (rGO) sheets. Two controlled sizes of graphene sheets (100 nm vs. 45 μm average lateral dimensions) were prepared to study two-electrode system performance. The nano-size graphenes led to the formation of mesoporous films, resulting in higher capacitance, better capacitance retension and lower equivalent series resistance (ESR), indicating better surface usability for diffusion and accessibility of electrolyte ions by shortening transport paths (compared with horizontally stacked films from micro-sized graphenes). For studies using an aqueous electrolyte,more » the maximum specific capacitance of nano-rGO film was 302 F/g (at 1 A/g with 4.3 mg/cm 2 of mass loading), which was ~2.4 times higher than micro-rGO film, and achieved a ~67% reduced ESR. With an organic electrolyte, the nano-rGO delivered ~4.2 times higher capacitance (115 F/g at 2 A/g with 4.3 mg/cm 2), 4.0 times lower IR drops, and an order-of-magnitude lower charge-transfer resistance with an energy density of 18.7 Wh/kg. Finally, the results of this work indicate that the size control of graphene sheet particles for film deposit electrodes can be a simple but effective approach to improve supercapacitor performance.« less

A magnetic braking and sensing technique for deceleration and recovery of moving non-magnetic metallic particles

NASA Astrophysics Data System (ADS)

Cheng, David; Yoshinaka, Akio; Wu, Lawrence

2018-05-01

A magnetic braking and sensing technique developed as a potential alternative to assist with the non-contact deceleration and detection of explosively dispersed non-magnetic metallic particles is discussed. In order to verify the feasibility of such a technique and gain an understanding of how the underlying forces scale with particle size and velocity, a study was conducted whereby an aluminum particle moving along a spatially varying but time-invariant magnetic field was modeled and the corresponding experiment performed.

Attachment of micro- and nano-particles on tipless cantilevers for colloidal probe microscopy.

PubMed

D'Sa, Dexter J; Chan, Hak-Kim; Chrzanowski, Wojciech

2014-07-15

Current colloidal probe preparation techniques face several challenges in the production of functional probes using particles ⩽5 μm. Challenges include: glue encapsulated particles, glue altered particle properties, improper particle or agglomerate attachment, and lengthy procedures. We present a method to rapidly and reproducibly produce functional micro and nano-colloidal probes. Using a six-step procedure, cantilevers mounted on a custom designed 45° holder were used to approach and obtain a minimal amount of epoxy resin (viscosity of ∼14,000 cP) followed by a single micron/nano particle on the apex of a tipless cantilever. The epoxy and particles were prepared on individual glass slides and subsequently affixed to a 10× or 40× optical microscope lens using another custom designed holder. Scanning electron microscopy and comparative glue-colloidal probe measurements were used to confirm colloidal probe functionality. The method presented allowed rapid and reproducible production of functional colloidal probes (80% success). Single nano-particles were prominently affixed to the apex of the cantilever, unaffected by the epoxy. Nano-colloidal probes were used to conduct topographical, instantaneous force, and adhesive force mapping measurements in dry and liquid media conveying their versatility and functionality in studying nano-colloidal systems. Copyright © 2014 Elsevier Inc. All rights reserved.

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

PubMed

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

2018-04-01

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

Building bio-assays with magnetic particles on a digital microfluidic platform.

PubMed

Kokalj, Tadej; Pérez-Ruiz, Elena; Lammertyn, Jeroen

2015-09-25

Digital microfluidics (DMF) has emerged as a promising liquid handling technology for a variety of applications, demonstrating great potential both in terms of miniaturization and automation. DMF is based on the manipulation of discrete, independently controllable liquid droplets, which makes it highly reconfigurable and reprogrammable. One of its most exclusive advantages, compared to microchannel-based microfluidics, is its ability to precisely handle solid nano- and microsized objects, such as magnetic particles. Magnetic particles have become very popular in the last decade, since their high surface-to-volume ratio and the possibility to magnetically separate them from the matrix make them perfect suitable as a solid support for bio-assay development. The potential of magnetic particles in DMF-based bio-assays has been demonstrated for various applications. In this review we discuss the latest developments of magnetic particle-based DMF bio-assays with the aim to present, identify and analyze the trends in the field. We also discuss the state-of-the art of device integration, current status of commercialization and issues that still need to be addressed. With this paper we intend to stimulate researchers to exploit and unveil the potential of these exciting tools, which will shape the future of modern biochemistry, microbiology and biomedical diagnostics. Copyright © 2015 Elsevier B.V. All rights reserved.

Accurate quantification of magnetic particle properties by intra-pair magnetophoresis for nanobiotechnology

NASA Astrophysics Data System (ADS)

van Reenen, Alexander; Gao, Yang; Bos, Arjen H.; de Jong, Arthur M.; Hulsen, Martien A.; den Toonder, Jaap M. J.; Prins, Menno W. J.

2013-07-01

The application of magnetic particles in biomedical research and in-vitro diagnostics requires accurate characterization of their magnetic properties, with single-particle resolution and good statistics. Here, we report intra-pair magnetophoresis as a method to accurately quantify the field-dependent magnetic moments of magnetic particles and to rapidly generate histograms of the magnetic moments with good statistics. We demonstrate our method with particles of different sizes and from different sources, with a measurement precision of a few percent. We expect that intra-pair magnetophoresis will be a powerful tool for the characterization and improvement of particles for the upcoming field of particle-based nanobiotechnology.

Minimum ignition temperature of nano and micro Ti powder clouds in the presence of inert nano TiO2 powder.

PubMed

Yuan, Chunmiao; Amyotte, Paul R; Hossain, Md Nur; Li, Chang

2014-06-30

Minimum ignition temperature (MIT) of micro Ti powder increased gradually with increases in nano-sized TiO2 employed as an inertant. Solid TiO2 inertant significantly reduced ignition hazard of micro Ti powder in contact with hot surfaces. The MIT of nano Ti powder remained low (583 K), however, even with 90% TiO2. The MIT of micro Ti powder, when mixed with nano Ti powder at concentrations as low as 10%, decreased so dramatically that its application as a solid fuel may be possible. A simple MIT model was proposed for aggregate particle size estimation and better understanding of the inerting effect of nano TiO2 on MIT. Estimated particle size was 1.46-1.51 μm larger than that in the 20-L sphere due to poor dispersion in the BAM oven. Calculated MITs were lower than corresponding empirically determined values for micro Ti powder because nano-sized TiO2 coated the micro Ti powder, thereby decreasing its reaction kinetics. In the case of nano Ti powder, nano-sized TiO2 facilitated dispersion of nano Ti powder which resulted in a calculated MIT that was greater than the experimentally determined value. Copyright © 2014 Elsevier B.V. All rights reserved.

Magnetic microscopic imaging with an optically pumped magnetometer and flux guides

DOE PAGES

Kim, Young Jin; Savukov, Igor Mykhaylovich; Huang, Jen -Huang; ...

2017-01-23

Here, by combining an optically pumped magnetometer (OPM) with flux guides (FGs) and by installing a sample platform on automated translation stages, we have implemented an ultra-sensitive FG-OPM scanning magnetic imaging system that is capable of detecting magnetic fields of ~20 pT with spatial resolution better than 300 μm (expected to reach ~10 pT sensitivity and ~100 μm spatial resolution with optimized FGs). As a demonstration of one possible application of the FG-OPM device, we conducted magnetic imaging of micron-size magnetic particles. Magnetic imaging of such particles, including nano-particles and clusters, is very important for many fields, especially for medicalmore » cancer diagnostics and biophysics applications. For rapid, precise magnetic imaging, we constructed an automatic scanning system, which holds and moves a target sample containing magnetic particles at a given stand-off distance from the FG tips. We show that the device was able to produce clear microscopic magnetic images of 10 μm-size magnetic particles. In addition, we also numerically investigated how the magnetic flux from a target sample at a given stand-off distance is transmitted to the OPM vapor cell.« less

A polymer solution technique for the synthesis of nano-sized Li 2TiO 3 ceramic breeder powders

NASA Astrophysics Data System (ADS)

Jung, Choong-Hwan; Lee, Sang Jin; Kriven, Waltraud M.; Park, Ji-Yeon; Ryu, Woo-Seog

2008-02-01

Nano-sized Li 2TiO 3 powder was fabricated by an organic-inorganic solution route. A steric entrapment route employing ethylene glycol was used for the preparation of the nano-sized Li 2TiO 3 particles. Titanium isopropoxide and lithium nitrate were dissolved in liquid-type ethylene glycol without any precipitation. With the optimum amount of the polymer, the metal cations (Li and Ti) were dispersed in the solution and a homogeneous polymeric network was formed. The organic-inorganic precursor gels were turned to crystalline powders through an oxidation reaction during a calcination process. The dried precursor gel showed the carbon-free Li 2TiO 3 crystalline form which was observed above 400 °C. The primary particle size of the carbon-free Li 2TiO 3 was about 70 nm, and the structure of the crystallized powder was porous and agglomerated. The powder compact was densified to 92% of TD at a relatively low sintering temperature of 1100 °C for 2 h.

Challenges in the development of magnetic particles for therapeutic applications.

PubMed

Barry, Stephen E

2008-09-01

Certain iron-based particle formulations have useful magnetic properties that, when combined with low toxicity and desirable pharmacokinetics, encourage their development for therapeutic applications. This mini-review begins with background information on magnetic particle use as MRI contrast agents and the influence of material size on pharmacokinetics and tissue penetration. Therapeutic investigations, including (1) the loading of bioactive materials, (2) the use of stationary, high-gradient (HG) magnetic fields to concentrate magnetic particles in tissues or to separate material bound to the particles from the body, and (3) the application of high power alternating magnetic fields (AMF) to generate heat in magnetic particles for hyperthermic therapeutic applications are then surveyed. Attention is directed mainly to cancer treatment, as selective distribution to tumors is well-suited to particulate approaches and has been a focus of most development efforts. While magnetic particles have been explored for several decades, their use in therapeutic products remains minimal; a discussion of future directions and potential ways to better leverage magnetic properties and to integrate their use into therapeutic regimens is discussed.

Size effects in the magnetic properties of ε-Fe{sub 2}O{sub 3} nanoparticles

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

Dubrovskiy, A. A., E-mail: andre-do@yandex.ru; International Laboratory of High Magnetic Fields and Low Temperatures, Wroclaw 53-421; Balaev, D. A.

2015-12-07

We report the results of comparative analysis of magnetic properties of the systems based on ε-Fe{sub 2}O{sub 3}, nanoparticles with different average sizes (from ∼3 to 9 nm) and dispersions. The experimental data for nanoparticles higher than 6–8 nm in size are consistent with the available data, specifically, the transition to the magnetically ordered state occurs at a temperature of ∼500 K and the anomalies of magnetic properties observed in the range of 80–150 K correspond to the magnetic transition. At the same time, Mőssbauer and ferromagnetic resonance spectroscopy data as well as the results of static magnetic measurements show that at room temperaturemore » all the investigated samples contain ε-Fe{sub 2}O{sub 3} particles that exhibit the superparamagnetic behavior. It was established that the magnetic properties of nanoparticles significantly change with a decrease in their size to ∼6 nm. According to high-resolution electron microscopy and Mőssbauer spectroscopy data, the particle structure can be attributed to the ε–modification of trivalent iron oxide; meanwhile, the temperature of the magnetic order onset in these particles is increased, the well-known magnetic transition in the range of 80–150 K does not occur, the crystallographic magnetic anisotropy constant is significantly reduced, and the surface magnetic anisotropy plays a decisive role. This is apparently due to redistribution of cations over crystallographic positions with decreasing particle size, which was established using Mössbauer spectra. As the particle size is decreased and the fraction of surface atoms is increased, the contribution of an additional magnetic subsystem formed in a shell of particles smaller than ∼4 nm becomes significant, which manifests itself in the static magnetic measurements as paramagnetic contribution.« less

[Preparation of nano-nacre artificial bone].

PubMed

Chen, Jian-ting; Tang, Yong-zhi; Zhang, Jian-gang; Wang, Jian-jun; Xiao, Ying

2008-12-01

To assess the improvements in the properties of nano-nacre artificial bone prepared on the basis of nacre/polylactide acid composite artificial bone and its potential for clinical use. The compound of nano-scale nacre powder and poly-D, L-lactide acid (PDLLA) was used to prepare the cylindrical hollow artificial bone, whose properties including raw material powder scale, pore size, porosity and biomechanical characteristics were compared with another artificial bone made of micron-scale nacre powder and PDLLA. Scanning electron microscope showed that the average particle size of the nano-nacre powder was 50.4-/+12.4 nm, and the average pore size of the artificial bone prepared using nano-nacre powder was 215.7-/+77.5 microm, as compared with the particle size of the micron-scale nacre powder of 5.0-/+3.0 microm and the pore size of the resultant artificial bone of 205.1-/+72.0 microm. The porosities of nano-nacre artificial bone and the micron-nacre artificial bone were (65.4-/+2.9)% and (53.4-/+2.2)%, respectively, and the two artificial bones had comparable compressive strength and Young's modulus, but the flexural strength of the nano-nacre artificial bone was lower than that of the micro-nacre artificial bone. The nano-nacre artificial bone allows better biodegradability and possesses appropriate pore size, porosity and biomechanical properties for use as a promising material in bone tissue engineering.

Particle size dependent confinement and lattice strain effects in LiFePO4.

PubMed

Shahid, Raza; Murugavel, Sevi

2013-11-21

We report the intrinsic electronic properties of LiFePO4 (LFP) with different particle sizes measured by broad-band impedance spectroscopy and diffuse reflectance spectroscopy. The electronic properties show typical size-dependent effects with decreasing particle size (up to 150 nm). However, at the nanoscale level, we observed an enhancement in the polaronic conductivity about an order of magnitude. We found that the origin of the enhanced electronic conductivity in LFP is due to the significant lattice strain associated with the reduction of particle size. The observed lattice strain component corresponds to the compressive part which leads to a decrease in the hopping length of the polarons. We reproduce nonlinearities in the transport properties of LFP with particle size, to capture the interplay between confinement and lattice strain, and track the effects of strain on the electron-phonon interactions. These results could explain why nano-sized LFP has a better discharge capacity and higher rate capability than the bulk counterpart. We suggest that these new correlations will bring greater insight and better understanding for the optimization of LFP as a cathode material for advanced lithium ion batteries.

Shape and edge dependent electronic and magnetic properties of silicene nano-flakes

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

Mohan, Brij, E-mail: brijmohanhpu@yahoo.com; Pooja,; Ahluwalia, P. K.

2015-06-24

We performed first-principle study of the geometric, electronic and magnetic properties of arm-chair and zigzag edge silicene nano-flakes of triangular and hexagonal shapes. Electronic properties of silicene nano-flakes show strong dependence on their edge structure and shape. The considered nanostructures shows energy gap ranging ∼ 0.4 – 1.0 eV. Zigzag edged triangular nano-flake is magnetic and semiconducting in nature with 4.0 µ{sub B} magnetic moment and ∼ 0.4 eV energy gap.

Magnetic iron oxide nanoparticles (MIONs) cross-linked natural polymer-based hybrid gel beads: Controlled nano anti-TB drug delivery application.

PubMed

Kesavan, Mookkandi Palsamy; Ayyanaar, Srinivasan; Vijayakumar, Vijayaparthasarathi; Dhaveethu Raja, Jeyaraj; Annaraj, Jamespandi; Sakthipandi, Kathiresan; Rajesh, Jegathalaprathaban

2018-04-01

The nanosized rifampicin (RIF) has been prepared to increase the solubility in aqueous solution, which leads to remarkable enhancement of its bioavailability and their convenient delivery system studied by newly produced nontoxic, biodegradable magnetic iron oxide nanoparticles (MIONs) cross-linked polyethylene glycol hybrid chitosan (mCS-PEG) gel beads. The functionalization of both nano RIF and mCS-PEG gel beads were studied using various spectroscopic and microscopic techniques. The size of prepared nano RIF was found to be 70.20 ± 3.50 nm. The mechanical stability and swelling ratio of the magnetic gel beads increased by the addition of PEG with a maximum swelling ratio of 38.67 ± 0.29 g/g. Interestingly, this magnetic gel bead has dual responsive assets in the nano drug delivery application (pH and the magnetic field). As we expected, magnetic gel beads show higher nano drug releasing efficacy at acidic medium (pH = 5.0) with maximum efficiency of 71.00 ± 0.87%. This efficacy may also be tuned by altering the external magnetic field and the weight percentage (wt%) of PEG. These results suggest that such a dual responsive magnetic gel beads can be used as a potential system in the nano drug delivery applications. © 2017 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 106A: 1039-1050, 2018. © 2017 Wiley Periodicals, Inc.

Influence of Shell Thickness on the Colloidal Stability of Magnetic Core-Shell Particle Suspensions