Structural and magnetic properties of chromium doped zinc ferrite

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

Sebastian, Rintu Mary; Thankachan, Smitha; Xavier, Sheena

2014-01-28

Zinc chromium ferrites with chemical formula ZnCr{sub x}Fe{sub 2−x}O{sub 4} (x = 0.0, 0.2, 0.4, 0.6, 0.8, 1.0) were prepared by Sol - Gel technique. The structural as well as magnetic properties of the synthesized samples have been studied and reported here. The structural characterizations of the samples were analyzed by using X – Ray Diffraction (XRD), Fourier Transform Infrared Spectroscopy (FTIR), Scanning Electron Microscope (SEM), and Transmission Electron Microscope (TEM). The single phase spinel cubic structure of all the prepared samples was tested by XRD and FTIR. The particle size was observed to decrease from 18.636 nm to 6.125more » nm by chromium doping and induced a tensile strain in all the zinc chromium mixed ferrites. The magnetic properties of few samples (x = 0.0, 0.4, 1.0) were investigated using Vibrating Sample Magnetometer (VSM)« less

Piper nigrum Leaf and Stem Assisted Green Synthesis of Silver Nanoparticles and Evaluation of Its Antibacterial Activity Against Agricultural Plant Pathogens

PubMed Central

Paulkumar, Kanniah; Gnanajobitha, Gnanadhas; Vanaja, Mahendran; Rajeshkumar, Shanmugam; Malarkodi, Chelladurai; Pandian, Kannaiyan; Annadurai, Gurusamy

2014-01-01

Utilization of biological materials in synthesis of nanoparticles is one of the hottest topics in modern nanoscience and nanotechnology. In the present investigation, the silver nanoparticles were synthesized by using the leaf and stem extract of Piper nigrum. The synthesized nanoparticle was characterized by UV-vis spectroscopy, X-ray diffraction (XRD), scanning electron microscope (SEM), transmission electron microscope (TEM), energy dispersive X-ray analysis (EDAX), and Fourier Transform Infrared Spectroscopy (FTIR). The observation of the peak at 460 nm in the UV-vis spectra for leaf- and stem-synthesized silver nanoparticles reveals the reduction of silver metal ions into silver nanoparticles. Further, XRD analysis has been carried out to confirm the crystalline nature of the synthesized silver nanoparticles. The TEM images show that the leaf- and stem-synthesized silver nanoparticles were within the size of about 7–50 nm and 9–30 nm, respectively. The FTIR analysis was performed to identify the possible functional groups involved in the synthesis of silver nanoparticles. Further, the antibacterial activity of the green-synthesized silver nanoparticles was examined against agricultural plant pathogens. The antibacterial property of silver nanoparticles is a beneficial application in the field of agricultural nanotechnology. PMID:24558336

Synthesis, characterization and antibacterial activity of colloidal NiO nanoparticles.

PubMed

Khashan, Khawlah Salah; Sulaiman, Ghassan Mohammad; Abdul Ameer, Farah Abdul Kareem; Napolitano, Giuliana

2016-03-01

The Colloidal solutions of nickel oxide (NiO) nanoparticles synthesized via Nd-Yag pulse ablation of nickel immersed in H2O were studied. The created nanoparticles were characterized by UV-VIS absorption, Fourier transform infrared spectroscopy (FTIR) and transmission electron microscope (TEM). FTIR characterization confirms the formation of nickel oxide nanoparticles. The optical band gap values, determined by UV-VIS absorption measurements, are found to be (4.5 ev). TEM shows that nanoparticles size ranged from 2-21 nm. The antimicrobial activity was carried out against pseudomonas aurogenisa, Escherichia coli (gram negative bacteria), Staphylococcus aureus and Streptococcus pneumonia (gram positive bacteria). The NiO nanoparticles showed inhibitory activity in both strains of bacteria with best selectivity against gram-positive bacteria. The findings of present study indicate that NiO nanoparticles could potentiate the permeability of bacterial cell wall, and remarkably increase the accumulation of amoxicillin in bacteria, suggesting that NiO nanoparticles together with amoxicillin would facilitate the synergistic impact on growth inhibition of bacterial strains.

Solution combustion method for synthesis of nanostructured hydroxyapatite, fluorapatite and chlorapatite

NASA Astrophysics Data System (ADS)

Zhao, Junjie; Dong, Xiaochen; Bian, Mengmeng; Zhao, Junfeng; Zhang, Yao; Sun, Yue; Chen, JianHua; Wang, XuHong

2014-09-01

Hydroxyapatite (HAP), fluorapatite (Fap) and chlorapatite (Clap) were prepared by solution combustion method with further annealing at 800 °C. The characterization and structural features of the synthesized powders were evaluated by the powder X-ray diffraction (XRD, Fourier transform infrared spectroscopy (FT-IR), scanning electron microscope (SEM) and transmission electron microscopy (TEM) techniques. Characterization results from XRD and Rietveld analysis revealed that OH- in the HAP lattice were gradually substituted with the increase of F- and Cl- content and totally substituted at the molar concentration of 0.28 and 0.6, respectively. The results from FI-IR have also confirmed the incorporation of substituted anions in the apatite structure.

Nanocellulose based polymer composite for acoustical materials

NASA Astrophysics Data System (ADS)

Farid, Mohammad; Purniawan, Agung; Susanti, Diah; Priyono, Slamet; Ardhyananta, Hosta; Rahmasita, Mutia E.

2018-04-01

Natural fibers are biodegradable materials that are innovatively and widely used for composite reinforcement in automotive components. Nanocellulose derived from natural fibers oil palm empty bunches have properties that are remarkable for use as a composite reinforcement. However, there have not been many investigations related to the use of nanocellulose-based composites for wideband sound absorption materials. The specimens of nanocellulose-based polyester composite were prepared using a spray method. An impedance tube method was used to measure the sound absorption coefficient of this composite material. To reveal the characteristics of the nanocellulose-based polyester composite material, SEM (scanning electron microscope), TEM (Transmission Electron Microscope), FTIR (Fourier Transform Infra Red), TGA (Thermogravimetric Analysis), and density tests were performed. Sound absorption test results showed the average value of sound absorption coefficient of 0.36 to 0,46 for frequency between 500 and 4000 Hz indicating that this nanocellulose-based polyester composite materials had a tendency to wideband sound absorption materials and potentially used as automotive interior materials.

[Studies on interaction of acid-treated nanotube titanic acid and amino acids].

PubMed

Zhang, Huqin; Chen, Xuemei; Jin, Zhensheng; Liao, Guangxi; Wu, Xiaoming; Du, Jianqiang; Cao, Xiang

2010-06-01

Nanotube titanic acid (NTA) has distinct optical and electrical character, and has photocatalysis character. In accordance with these qualities, NTA was treated with acid so as to enhance its surface activity. Surface structures and surface groups of acid-treated NTA were characterized and analyzed by Transmission Electron Microscope (TEM) and Fourier Transform Infrared Spectrometry (FT-IR). The interaction between acid-treated NTA and amino acids was investigated. Analysis results showed that the lengths of acid-treated NTA became obviously shorter. The diameters of nanotube bundles did not change obviously with acid-treating. Meanwhile, the surface of acid-treated NTA was cross-linked with carboxyl or esterfunction. In addition, acid-treated NTA can catch amino acid residues easily, and then form close combination.

Morphological and spectroscopic analysis of cellulose nanocrystals extracted from oil palm empty fruit bunch fiber

NASA Astrophysics Data System (ADS)

Dasan, Y. K.; Bhat, A. H.; Faiz, A.

2015-07-01

This work evaluates the use of oil palm empty fruit bunch (OPEFB) fiber as a source of cellulose to obtain nanocrystalline cellulose (CNC) by acid hydrolysis reaction. The raw OPEFB fibers were pretreated with aqueous Sodium hydroxide at 80°C followed by bleaching treatment and further hydrolyzed with Sulphuric acid at 45°C with limited range of hydrolysis time and acid concentration. The resulting CNC's were characterized for spectroscopic, crystallographic and morphological properties using Fourier Transform Infrared Spectroscopy (FTIR), X-ray Diffractometer (XRD), Transmission Electron Microscope (TEM) and Atomic Force Microscopy (AFM). Finding of this study shows that the properties of CNC's are strongly dependent on the hydrolysis time and acid concentration.

Biosynthesis of CdS nanoparticles in banana peel extract.

PubMed

Zhou, Guang Ju; Li, Shuo Hao; Zhang, Yu Cang; Fu, Yun Zhi

2014-06-01

Cadmium sulfide (CdS) nanoparticles (NPs) were synthesized by using banana peel extract as a convenient, non-toxic, eco-friendly 'green' capping agent. Cadmium nitrate and sodium sulfide are main reagents. A variety of CdS NPs are prepared through changing reaction conditions (banana extracts, the amount of banana peel extract, solution pH, concentration and reactive temperature). The prepared CdS colloid displays strong fluorescence spectrum. X-ray diffraction analysis demonstrates the successful formation of CdS NPs. Fourier transform infra-red (FTIR) spectrogram indicates the involvement of carboxyl, amine and hydroxyl groups in the formation of CdS NPs. Transmission electron microscope (TEM) result reveals that the average size of the NPs is around 1.48 nm.

Erratum to: Psammoma bodies in two types of human ovarian tumours: a mineralogical study

NASA Astrophysics Data System (ADS)

Meng, Fanlu; Wang, Changqiu; Li, Yan; Lu, Anhuai; Mei, Fang; Liu, Jianying; Du, Jingyun; Zhang, Yan

2015-06-01

Psammoma body (PB) is a common form of calcification in pathological diagnosis and closely relevant to tumours. This paper focuses on the mineralogical characteristics of PBs in ovarian serous cancer and teratoma by using polarization microscope (POM), environmental scanning electron microscope (ESEM), micro-Fourier transform infrared spectroscopy (micro-FT-IR), transmission electron microscope (TEM), micro-area synchrotron radiation X-ray powder diffraction (μ-SRXRD) and fluorescence (μ-SRXRF). Both the PBs in tissues and separated from eight typical cases were investigated. POM and ESEM observation revealed the inside-out growth pattern of PBs. μ-SRXRD and micro-FT-IR results demonstrated the dominant mineral phase of PBs in ovarian serous cancer and teratoma was AB-type carbonate hydroxyapatite (Ca10[(PO4)6-x-y(CO3)x(HPO4)y][(OH)2-u(CO3)u] with 0 ≤ x,y,u ≤ 2). As observed by ESEM and TEM, the layer-rich PBs in teratoma were up to 70 μm and mainly consisted of 5 nm-wide, 5-12 nm-long columnar crystals; the PBs in ovarian serous cancer with a maximum diameter of 35 μm were composed of slightly longer columnar crystals and granulates with 20-100 nm in diameter. The selected area electron diffraction patterns showed dispersed polycrystalline diffraction rings with arching behavior of (002) diffraction, indicating the aggregated nanocrystals grew in the preferred orientation of (002) face. The EDX and μ-SRXRF results together indicated the existence of Na, Mg, Zn and Sr in PBs. These detailed mineralogical characteristics may help uncover the nature of the pathological PBs in ovary.

Psammoma bodies in two types of human ovarian tumours: a mineralogical study

NASA Astrophysics Data System (ADS)

Fanlu, Meng; Changqiu, Wang; Yan, Li; Anhuai, Lu; Fang, Mei; Jianying, Liu; Jingyun, Du; Yan, Zhang

2015-06-01

Psammoma body (PB) is a common form of calcification in pathological diagnosis and closely relevant to tumours. This paper focuses on the mineralogical characteristics of PBs in ovarian serous cancer and teratoma by using polarization microscope (POM), environmental scanning electron microscope (ESEM), micro-Fourier transform infrared spectroscopy (micro-FT-IR), transmission electron microscope (TEM), micro-area synchrotron radiation X-ray powder diffraction (μ-SRXRD) and fluorescence (μ-SRXRF). Both the PBs in tissues and separated from eight typical cases were investigated. POM and ESEM observation revealed the inside-out growth pattern of PBs. μ-SRXRD and micro-FT-IR results demonstrated the dominant mineral phase of PBs in ovarian serous cancer and teratoma was AB-type carbonate hydroxyapatite (Ca10[(PO4)6-x-y(CO3)x(HPO4 2-)y][(OH)2-u(CO3)u] with 0 ≤ x,y,u ≤ 2). As observed by ESEM and TEM, the layer-rich PBs in teratoma were up to 70 μm and mainly consisted of 5 nm-wide, 5-12 nm-long columnar crystals; the PBs in ovarian serous cancer with a maximum diameter of 35 μm were composed of slightly longer columnar crystals and granulates with 20-100 nm in diameter. The selected area electron diffraction patterns showed dispersed polycrystalline diffraction rings with arching behavior of (002) diffraction, indicating the aggregated nanocrystals grew in the preferred orientation of (002) face. The EDX and μ-SRXRF results together indicated the existence of Na, Mg, Zn and Sr in PBs. These detailed mineralogical characteristics may help uncover the nature of the pathological PBs in ovary.

Green synthesis and characterization of Au@Pt core-shell bimetallic nanoparticles using gallic acid

NASA Astrophysics Data System (ADS)

Zhang, Guojun; Zheng, Hongmei; Shen, Ming; Wang, Lei; Wang, Xiaosan

2015-06-01

In this study, we developed a facile and benign green synthesis approach for the successful fabrication of well-dispersed urchin-like Au@Pt core-shell nanoparticles (NPs) using gallic acid (GA) as both a reducing and protecting agent. The proposed one-step synthesis exploits the differences in the reduction potentials of AuCl4- and PtCl62-, where the AuCl4- ions are preferentially reduced to Au cores and the PtCl62- ions are then deposited continuously onto the Au core surface as a Pt shell. The as-prepared Au@Pt NPs were characterized by transmission electron microscope (TEM); high-resolution transmission electron microscope (HR-TEM); scanning electron microscope (SEM); UV-vis absorption spectra (UV-vis); X-ray diffraction (XRD); Fourier transmission infrared spectra (FT-IR). We systematically investigated the effects of some experimental parameters on the formation of the Au@Pt NPs, i.e., the reaction temperature, the molar ratios of HAuCl4/H2PtCl6, and the amount of GA. When polyvinylpyrrolidone K-30 (PVP) was used as a protecting agent, the Au@Pt core-shell NPs obtained using this green synthesis method were better dispersed and smaller in size. The as-prepared Au@Pt NPs exhibited better catalytic activity in the reaction where NaBH4 reduced p-nitrophenol to p-aminophenol. However, the results showed that the Au@Pt bimetallic NPs had a lower catalytic activity than the pure Au NPs obtained by the same method, which confirmed the formation of Au@Pt core-shell nanostructures because the active sites on the surfaces of the Au NPs were covered with a Pt shell.

The synthesis of Ag/polypyrrole coaxial nanocables via ion adsorption method using different oxidants

NASA Astrophysics Data System (ADS)

Qiu, Teng; Xie, Huxiao; Zhang, Jiangru; Zahoor, Amad; Li, Xiaoyu

2011-03-01

Ag/polypyrrole (PPy) coaxial nanocables (NCs) were synthesized by an ion adsorption method. In this method, the pre-made Ag nanowires (NWs) were dispersed in the aqueous solution of copper acetate (Cu(Ac)2), and the Cu2+ ions adsorbed onto the surface of Ag NWs can oxidize pyrrole monomers to polymerize into uniform PPy sheath outside Ag NWs after the Cu(Ac)2-treated Ag NWs were re-dispersed in the aqueous solution of pyrrole. The morphology of NCs was characterized by transmission electron microscope (TEM) and scanning electron microscope (SEM). The relationship between the thickness of polymer sheath and the concentration of Cu(Ac)2 was established. As Cu(Ac)2 which served as the oxidant can also be replaced by AgNO3 in this synthesis, the differences on the structure of polymer sheath caused by different oxidants were studied by surface-enhanced Raman scattering (SERS), high-resolution transmission electron microscope (HR-TEM), Fourier transform infrared spectroscopy (FT-IR), and X-ray photoelectron spectroscopy (XPS). Comparing with the characterization results of Ag/PPy NCs synthesized using AgNO3 as the oxidant which indicates the random arrangement of PPy chains at the interface between polymer sheath and Ag NWs, PPy chain oxidized by Cu2+ tends to show a relatively ordered conformation at the interface with the pyrrole rings identically taking the plane vertical to the surface of Ag NWs. In addition, although the main part of the polymer sheath was composed of PPy whatever kind of oxidant was used, the sheath of the NCs oxidized by Cu2+ is typical for the existence of Cu(I)-pyrrole coordinate structures with strong Cu(I)-N bond signal shown in XPS characterization.

The effect of PVP on morphology, optical properties and electron paramagnetic resonance of Zn0.5Co0.5Fe2-xPrxO4 nanoparticles

NASA Astrophysics Data System (ADS)

Bitar, Z.; El-Said Bakeer, D.; Awad, R.

2017-07-01

Zinc Cobalt nano ferrite doped with Praseodymium, Zn0.5Co0.5Fe2-xPrxO4 (0 ≤ x ≤ 0.2), were prepared by co-precipitation method from an aqueous solution containing metal chlorides and two concentrations of poly(vinylpyrrolidone) (PVP) 0 and 30g/L as capping agent. The samples were characterized using X-ray powder diffraction (XRD), Transmission Electron Microscope (TEM), UV-visible optical spectroscopy, Fourier transform infrared (FTIR) and Electron Paramagnetic Resonance (EPR). XRD results display the formation of cubic spinel structure with space group Fd3m and the lattice parameter (a) is slightly decreased for PVP capping samples. The particle size that determined by TEM, decreases for PVP capping samples. The optical band energy Eg increases for PVP capping samples, confirming the variation of energy gap with the particle size. The FTIR results indicate that the metal oxide bands were shifted for the PVP capping samples. EPR data shows that the PVP addition increases the magnetic resonance field and hence decreases the g-factor.

Green synthesis of silver nanoparticles using marine algae Caulerpa racemosa and their antibacterial activity against some human pathogens

NASA Astrophysics Data System (ADS)

Kathiraven, T.; Sundaramanickam, A.; Shanmugam, N.; Balasubramanian, T.

2015-04-01

We present the synthesis and antibacterial activity of silver nanoparticles using Caulerpa racemosa, a marine algae. Fresh C. racemosa was collected from the Gulf of Mannar, Southeast coast of India. The seaweed extract was used for the synthesis of AgNO3 at room temperature. UV-visible spectrometry study revealed surface plasmon resonance at 413 nm. The characterization of silver nanoparticle was carried out using Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD) and transmission electron microscope (TEM). FT-IR measurements revealed the possible functional groups responsible for reduction and stabilization of the nanoparticles. X-ray diffraction analysis showed that the particles were crystalline in nature with face-centered cubic geometry.TEM micrograph has shown the formation of silver nanoparticles with the size in the range of 5-25 nm. The synthesized AgNPs have shown the best antibacterial activity against human pathogens such as Staphylococcus aureus and Proteus mirabilis. The above eco-friendly synthesis procedure of AgNPs could be easily scaled up in future for the industrial and therapeutic needs.

Green Synthesis of Silver Nanoparticles by using Eucalyptus Globulus Leaf Extract

NASA Astrophysics Data System (ADS)

Balamurugan, Madheswaran; Saravanan, Shanmugam

2017-12-01

A single step eco-friendly, energy efficient and economically scalable green method was employed to synthesize silver nanoparticles. In this work, the synthesis of silver nanoparticles using Eucalyptus globulus leaf extract as reducing and capping agent along with water as solvent at normal room temperature is described. Silver nanoparticles were prepared from aqueous silver nitrate solution by adding the leaf extract. The prepared nanoparticles were characterized by using UV-visible Spectrophotometer, X-ray diffractometer, High Resolution Transmission Electron Microscope (HR-TEM) and Fourier Transform Infrared Spectroscope (FTIS). X-ray diffraction studies brought to light the crystalline nature and the face centered cubic structure of the silver nanoparticles. Using HR-TEM. the nano sizes and morphology of the particles were studied. The mean sizes of the prepared silver nanoparticles ranged from 30 to 36 nm. The density of the particles was tuned by varying the molar ratio of silver nitrate. FTIS studies showed the functional group of organic molecules which were located on the surface of the silver nanoparticles. Originating from the leaf extracts, these organic molecules reduced and capped the particles.

Kyllinga brevifolia mediated greener silver nanoparticles

NASA Astrophysics Data System (ADS)

Isa, Norain; Bakhari, Nor Aziyah; Sarijo, Siti Halimah; Aziz, Azizan; Lockman, Zainovia

2017-12-01

Kyllinga brevifolia extract (KBE) was studied in this research as capping as well as reducing agent for the synthesis of greener plant mediated silver nanoparticles. This research was conducted in order to identify the compounds in the KBE that probable to work as reductant for the synthesis of Kyllinga brevifolia-mediated silver nanoparticles (AgNPs). Screening test such as Thin Layer Chromatography (TLC), Fourier Transform Infra-Red (FTIR), Carlo Erba Elemental analysis and Gas Chromatography-Mass Spectroscopy (GCMS) were used in identifying the natural compounds in KBE. The as-prepared AgNPs were characterized by UV-vis spectroscopy (UV-vis), Transmission Electron Microscope (TEM) and X-ray Diffraction (XRD). The TEM images showed that the as-synthesized silver have quasi-spherical particles are distributed uniformly with a narrow distribution from 5 nm to 40 nm. The XRD results demonstrated that the obtained AgNPs were face centre-cubic (FCC) structure. The catalytic activity of AgNPs on reduction of methylene blue (MB) using sodium borohydride (SB) was analyzed using UV-vis spectroscopy. This study showed that the efficacy of mediated AgNPs in catalysing the reduction of MB.

Photocatalytic degradation of organic contaminants under solar light using carbon dot/titanium dioxide nanohybrid, obtained through a facile approach

NASA Astrophysics Data System (ADS)

Hazarika, Deepshikha; Karak, Niranjan

2016-07-01

In the present study, a novel, simple and green method was developed to synthesize highly luminescent nitrogen containing carbon dot (CD) using carbon resources like bio-based citric acid and glycerol in the presence of cost free cow urine. The as-synthesized CD showed exciting wavelength dependent down- and up-conversion flourescence properties. To utilize the advantage of up-conversion flourescence, a nanohybrid (CD@TiO2) was synthesized from the above carbon resources and titanium butoxide through a facile one pot single step hydrothermal protocol. Nanomaterials like bare TiO2 and nanohybrid of TiO2 in presence of CD (CD/TiO2) were also synthesized for comparison purpose. The optical properties and structural characteristics of the prepared CD, bare TiO2, CD@TiO2 and CD/TiO2 were examined by Fourier transform infrared (FTIR), UV-vis and fluorescence spectroscopic, scanning electron microscopic (SEM), transmission electron microscopic (TEM) and X-ray diffraction (XRD) studies. The elemental compositions of bare CD and CD@TiO2 nanohybrid were obtained from EDX analyses. The poor crystalline nature and narrow distribution of spherical CD and anatase form of TiO2 were confirmed from XRD and TEM studies. Amongst the studied nanomaterials, CD@TiO2 exhibited the most promising photocatalytic degradation of organic pollutants like benzene and phenol as well as an anthrogenic pesticide under sunlight.

Morphological and spectroscopic analysis of cellulose nanocrystals extracted from oil palm empty fruit bunch fiber

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

Dasan, Y. K., E-mail: aamir.bhat@petronas.com.my; Bhat, A. H., E-mail: aamir.bhat@petronas.com.my; Faiz, A., E-mail: faizahmad@petronas.com.my

2015-07-22

This work evaluates the use of oil palm empty fruit bunch (OPEFB) fiber as a source of cellulose to obtain nanocrystalline cellulose (CNC) by acid hydrolysis reaction. The raw OPEFB fibers were pretreated with aqueous Sodium hydroxide at 80°C followed by bleaching treatment and further hydrolyzed with Sulphuric acid at 45°C with limited range of hydrolysis time and acid concentration. The resulting CNC’s were characterized for spectroscopic, crystallographic and morphological properties using Fourier Transform Infrared Spectroscopy (FTIR), X-ray Diffractometer (XRD), Transmission Electron Microscope (TEM) and Atomic Force Microscopy (AFM). Finding of this study shows that the properties of CNC’s aremore » strongly dependent on the hydrolysis time and acid concentration.« less

High-pressure freezing for scanning transmission electron tomography analysis of cellular organelles.

PubMed

Walther, Paul; Schmid, Eberhard; Höhn, Katharina

2013-01-01

Using an electron microscope's scanning transmission mode (STEM) for collection of tomographic datasets is advantageous compared to bright field transmission electron microscopic (TEM). For image formation, inelastic scattering does not cause chromatic aberration, since in STEM mode no image forming lenses are used after the beam has passed the sample, in contrast to regular TEM. Therefore, thicker samples can be imaged. It has been experimentally demonstrated that STEM is superior to TEM and energy filtered TEM for tomography of samples as thick as 1 μm. Even when using the best electron microscope, adequate sample preparation is the key for interpretable results. We adapted protocols for high-pressure freezing of cultivated cells from a physiological state. In this chapter, we describe optimized high-pressure freezing and freeze substitution protocols for STEM tomography in order to obtain high membrane contrast.

Synthesis of di-functional ligand and fluorescently labeling SiO2 microspheres

NASA Astrophysics Data System (ADS)

Chen, Kexu; Kang, Ming; Liu, Min; Shen, Simin; Sun, Rong

2018-05-01

In order to complete the fluorescent labeling of SiO2 microspheres, a kind of di-functional ligand was synthesized and purified, which could not only coordinate rare earth ions but also react with the active groups to bond host materials with an alkoxysilane groups. Fourier transform infrared spectroscopy (FT-IR), 1H NMR spectra, MS spectra, field emission scanning electron microscope (FESEM), transmission electron microscope (TEM), X-ray photoelectron spectroscopy (XPS) and luminescence spectrophotometer were used to study the structure of di-functional ligand and properties of fluorescent coupling agent and fluorescent labeled SiO2 microspheres. The optimal experiment conditions were acquired as follows: molar ratio as 1: 4 (MDBM: MICPTES), reaction time at 6 h and reaction temperature as 65 °C (yield up to 40%) through the orthogonal experiment and purification process. The results indicated that fluorescent coupling agent presented red photoluminesence of Eu3+ ions at 610 nm, and the absolute quantum yield was 11%. On the other hand, the hydrolysis of the coupling agent reacted on the surface of SiO2 microspheres and presented fluorescent labeling homogeneously.

Ligand exchange synthesis of organometallic Rh nanoparticles and application in explosive sensing

NASA Astrophysics Data System (ADS)

Srivastav, Amit K.; Agrawal, Bhavesh; Swami, Bhavya; Agrawal, Yadvendra K.; Maity, Prasenjit

2017-06-01

Alkyne {phenyl acetylene (PA) and 9-ethynylphenanthrene (EPT)}-ligated Rh nanoparticles ( 1 and 2, respectively) with mean diameter of 1.5 ± 0.2 nm were synthesized via a facile and high-yield biphasic ligand exchange protocol using similar sized ethylene glycol (EG)-stabilized Rh nanoparticles as precursors (EG:Rh). The synthesized organometallic Rh nanoparticles were convincingly characterized using several spectroscopic and microscopic techniques, e.g., Fourier transform infrared spectroscopy (FTIR), proton nuclear magnetic resonance (1H NMR), optical absorption spectroscopy (UV-Vis), photoluminescence spectroscopy (PL), powder X-ray diffraction (PXRD), X-ray photoelectron spectroscopy (XPS), and transmission electron microscope (TEM). We propose that the syntheses mechanism relies on catalytic acetylenic (≡C-H, carbon-hydrogen) bond breaking by EG:Rh followed by strong metal-carbon bond formation with a vinyldiene (>C═C═M) motif. The obtained 1 and 2 showed luminescence property, which arises from ligand structure through intraparticle conjugation. Electron-rich phenanthrene-ligated Rh nanoparticles ( 2) showed good sensing performance for detection of electron deficient nitro-aromatic explosive molecules (NA) in solution phase through luminescence quenching method.

Fabrication and characterization of a novel hydrophobic CaCO3 grafted by hydroxylated poly(vinyl chloride) chains

NASA Astrophysics Data System (ADS)

Bao, Lixia; Yang, Simei; Luo, Xin; Lei, Jingxin; Cao, Qiue; Wang, Jiliang

2015-12-01

The hydroxylated PVC (PVC-OH) was successfully synthesized by a suspension polymerization of vinyl chloride (VC), butyl acrylate (BA) and hydroxyethyl acrylate (HEA). Novel hydrophobic CaCO3 was then prepared by a urethane formation reaction between methylene diphenyl diisocyanate (MDI) and the sbnd OH groups both in the PVC-OH chains and on the surface of pristine CaCO3 particles. The effect of the PVC-OH content on the grafting ratio of treated CaCO3 particles was extensively investigated. Combining the result of Fourier transform infrared (FTIR) with that of water contact angle, it can be concluded that the hydrophobicity of CaCO3 had been efficiently improved by the PVC-OH segments grafted on the surface of CaCO3 particles. X-ray diffraction (XRD), thermal gravity analysis (TGA), scanning electron microscope (SEM) and transmission electron microscope (TEM) were also used to study crystalline behaviors, thermal stability and surface morphology of the modified CaCO3 particles, respectively. The change of specific surface area implying surface modification was investigated as well.

Optical, Magnetic and Photocatalytic Activity Studies of Li, Mg and Sr Doped and Undoped Zinc Oxide Nanoparticles.

PubMed

Shanthi, S I; Poovaragan, S; Arularasu, M V; Nithya, S; Sundaram, R; Magdalane, C Maria; Kaviyarasu, K; Maaza, M

2018-08-01

Nanoparticles of Li, Mg and Sr doped and undoped zinc oxide was prepared by simple precipitation method. The structural, optical, and magnetic properties of the samples were investigated by the Powder X-ray Diffraction (XRD), Scanning Electron Microscope (SEM), Transmission Electron Microscope (TEM), Fourier Transform Infrared (FTIR) spectroscopy, Ultra-violet Visible spectroscopy (UV-vis) spectra, Photoluminescence (PL) and Vibrational Sample Magnetometer (VSM). The Powder X-ray diffraction data confirm the formation of hexagonal wurtzite structure of all doped and undoped ZnO. The SEM photograph reveals that the pores availability and particles size in the range of 10 nm-50 nm. FTIR and UV-Visible spectra results confirm the incorporation of the dopant into the ZnO lattice nanostructure. The UV-Visible spectra indicate that the shift of blue region (lower wavelength) due to bandgap widening. Photoluminescence intensity varies with doping due to the increase of oxygen vacancies in prepared ZnO. The pure ZnO exist paramagnetic while doped (Li, Mg and Sr) ZnO exist ferromagnetic property. The photocatalytic activity of the prepared sample also carried out in detail.

Influence of the synthesis parameters on the properties of amidoxime grafted sepiolite nanocomposites

NASA Astrophysics Data System (ADS)

Taimur, Shaista; Yasin, Tariq

2017-11-01

Novel polyacrylonitrile (PAN) grafted sepiolite nanocomposites were synthesized via emulsion polymerization. The influence of synthesis parameters on the degree of grafting was studied by varying the concentrations of monomer, initiator and surfactant. The nitrile groups of PAN were chemically modified into amidoxime. Both the grafting and amidoxime percentages were determined gravimetrically and maximum grafting of 373% was achieved at 5% acrylonitrile, 1% surfactant and 0.1% initiator concentrations. The presence of vibration at 2242 cm-1 in Fourier transform infrared (FT-IR) spectrum and x-ray diffraction (XRD) reflection at 2θ = 16.9° (010) confirmed the grafting of PAN chains onto modified sepiolite. XRD patterns also indicated a decrease in crystallinity of sepiolite and appearance of new amorphous region in grafted nanocomposites. The morphological changes of sepiolite during silanization and grafting of PAN is also confirmed by field emission scanning electron microscope (FESEM). Transmission electron microscope (TEM) images clearly showed the shortening of fibers after silanization of sepiolite and the same were involved in heterogeneous nucleation in micelles. These developed amidoxime grafted sepiolite nanocomposites can be used as adsorbent for the metal recovery.

Fabrication and electric measurements of nanostructures inside transmission electron microscope.

PubMed

Chen, Qing; Peng, Lian-Mao

2011-06-01

Using manipulation holders specially designed for transmission electron microscope (TEM), nanostructures can be characterized, measured, modified and even fabricated in-situ. In-situ TEM techniques not only enable real-time study of structure-property relationships of materials at atomic scale, but also provide the ability to control and manipulate materials and structures at nanoscale. This review highlights in-situ electric measurements and in-situ fabrication and structure modification using manipulation holder inside TEM. Copyright © 2011 Elsevier B.V. All rights reserved.

Sulfur Nanoparticles Synthesis and Characterization from H2S Gas, Using Novel Biodegradable Iron Chelates in W/O Microemulsion

NASA Astrophysics Data System (ADS)

Deshpande, Aniruddha S.; Khomane, Ramdas B.; Vaidya, Bhalchandra K.; Joshi, Renuka M.; Harle, Arti S.; Kulkarni, Bhaskar D.

2008-06-01

Sulfur nanoparticles were synthesized from hazardous H2S gas using novel biodegradable iron chelates in w/o microemulsion system. Fe3+ malic acid chelate (0.05 M aqueous solution) was studied in w/o microemulsion containing cyclohexane, Triton X-100 and n-hexanol as oil phase, surfactant, co-surfactant, respectively, for catalytic oxidation of H2S gas at ambient conditions of temperature, pressure, and neutral pH. The structural features of sulfur nanoparticles have been characterized by X-ray diffraction (XRD), transmission electron microscope (TEM), energy dispersive spectroscopy (EDS), diffused reflectance infra-red Fourier transform technique, and BET surface area measurements. XRD analysis indicates the presence of α-sulfur. TEM analysis shows that the morphology of sulfur nanoparticles synthesized in w/o microemulsion system is nearly uniform in size (average particle size 10 nm) and narrow particle size distribution (in range of 5 15 nm) as compared to that in aqueous surfactant systems. The EDS analysis indicated high purity of sulfur (>99%). Moreover, sulfur nanoparticles synthesized in w/o microemulsion system exhibit higher antimicrobial activity (against bacteria, yeast, and fungi) than that of colloidal sulfur.

Alterations in mineral properties of zebrafish skeletal bone induced by liliput dtc232 gene mutation

NASA Astrophysics Data System (ADS)

Wang, Xiu-Mei; Cui, Fu-Zhai; Ge, Jun; Ma, Chen

2003-11-01

The alterations of mineral properties of bone by gene mutation in the zebrafish, which is associated with abnormal bone mineralization and bone diseases, were reported for the first time in this paper. Transmission electron microscope (TEM), Fourier transform infrared microspectroscopy (FTIRM) and thermogravimetric analysis (TGA) were used to investigate the changes in the mineral. Significant variations of the morphologies of the minerals and the mineral/matrix ratio after liliputdtc232(lil) gene mutation have been observed. The morphologies of the minerals, examined by TEM, revealed that the mutated mineral was in bigger size and the shape was block shaped but not plate shaped. The results of FTIRM indicated that the lil mutant zebrafish skeleton exhibited a greater mineral/matrix ratio (phosphate/matrix=4.86±0.28) than that of wild-type zebrafish bone (phosphate/matrix=4.17±0.67), which was confirmed by TGA analysis. Furthermore, the mineral of lil bone became less mature and crystalline with more ion substitutions. And the selected areas electron diffraction (SAED) patterns showed that the main crystal phases of the two type fishes were both hydroxyapatite. In addition, we have discussed the relationship among the mineral properties, nanomechanical properties and biomineralization process.

Green synthesis of Silver and Gold Nanoparticles for Enhanced catalytic and bactericidal activity

NASA Astrophysics Data System (ADS)

Naraginti, S.; Tiwari, N.; Sivakumar, A.

2017-11-01

A rapid one step green synthetic method using kiwi fruit extract was employed for preparation of silver and gold nanoparticles. The synthesized nanoparticles were successfully used as green catalysts for the reduction of 4-nitrophenol (4-NP) and methylene blue (MB). They also exhibited excellent antimicrobial activity against clinically isolated Pseudomonas aeruginosa (P.aeruginosa) and Staphylococcus aureus (S.aureus). It was noticed that with increase in concentration of the aqueous silver and gold solutions, particle size of the Ag and Au NPS showed increase as evidenced from UV-Visible spectroscopy and TEM micrograph. The method employed for the synthesis required only a few minutes for more than 90% formation of nanoparticles when the temperature was raised to 80°C. It was also noticed that the catalytic activity of nanoparticles depends upon the size of the particles. These nanoparticles were observed to be crystalline from the clear lattice fringes in the transmission electron microscopic (TEM) images, bright circular spots in the selected area electron diffraction (SAED) pattern and peaks in the X-ray diffraction (XRD) pattern. The Fourier-transform infrared (FTIR) spectrum indicated the presence of different functional groups in the biomolecule capping the nanoparticles.

Sulfur Nanoparticles Synthesis and Characterization from H2S Gas, Using Novel Biodegradable Iron Chelates in W/O Microemulsion

PubMed Central

2008-01-01

Sulfur nanoparticles were synthesized from hazardous H2S gas using novel biodegradable iron chelates in w/o microemulsion system. Fe3+–malic acid chelate (0.05 M aqueous solution) was studied in w/o microemulsion containing cyclohexane, Triton X-100 andn-hexanol as oil phase, surfactant, co-surfactant, respectively, for catalytic oxidation of H2S gas at ambient conditions of temperature, pressure, and neutral pH. The structural features of sulfur nanoparticles have been characterized by X-ray diffraction (XRD), transmission electron microscope (TEM), energy dispersive spectroscopy (EDS), diffused reflectance infra-red Fourier transform technique, and BET surface area measurements. XRD analysis indicates the presence of α-sulfur. TEM analysis shows that the morphology of sulfur nanoparticles synthesized in w/o microemulsion system is nearly uniform in size (average particle size 10 nm) and narrow particle size distribution (in range of 5–15 nm) as compared to that in aqueous surfactant systems. The EDS analysis indicated high purity of sulfur (>99%). Moreover, sulfur nanoparticles synthesized in w/o microemulsion system exhibit higher antimicrobial activity (against bacteria, yeast, and fungi) than that of colloidal sulfur.

Isolation and characterization of Bacillus cereus IST105 from electroplating effluent for detoxification of hexavalent chromium.

PubMed

Naik, Umesh Chandra; Srivastava, Shaili; Thakur, Indu Shekhar

2011-08-01

Electroplating industries are the main sources of heavy metals, chromium, nickel, lead, zinc, cadmium and copper. The highest concentrations of chromium (VI) in the effluent cause a direct hazards to human and animals. Therefore, there is a need of an effective and affordable biotechnological solution for removal of chromium from electroplating effluent. Bacterial strains were isolated from electroplating effluent to find out higher tolerant isolate against chromate. The isolate was identified by 16S rDNA sequence analysis. Absorbed chromium level of bacterium was determined by inductively coupled plasma-atomic emission spectrometer (ICP-AES), atomic absorption spectrophotometer (AAS), scanning electron microscope (SEM), transmission electron microscope (TEM) and energy dispersive X-ray analysis (EDX). Removal of metals by bacterium from the electroplating effluent eventually led to the detoxification of effluent confirmed by MTT assay. Conformational changes of functional groups of bacterial cell surface were studied through Fourier transform infrared spectroscopy. The chromate tolerant isolate was identified as Bacillus cereus. Bacterium has potency to remove more than 75% of chromium as measured by ICP-AES and AAS. The study indicated the accumulation of chromium (VI) on bacterial cell surface which was confirmed by the SEM-EDX and TEM analysis. The biosorption of metals from the electroplating effluent eventually led to the detoxification of effluent. The increased survivability of Huh7 cells cultured with treated effluent also confirmed the detoxification as examined by MTT assay. Isolated strain B. cereus was able to remove and detoxify chromium (VI). It would be an efficient tool of the biotechnological approach in mitigating the heavy metal pollutants.

Green biosynthesis of silver nanoparticles using leaves extract of Artemisia vulgaris and their potential biomedical applications.

PubMed

Rasheed, Tahir; Bilal, Muhammad; Iqbal, Hafiz M N; Li, Chuanlong

2017-10-01

Biosynthesis of nanoparticles from plant extracts is receiving enormous interest due to their abundant availability and a broad spectrum of bioactive reducing metabolites. In this study, the reducing potential of Artemisia vulgaris leaves extract (AVLE) was investigated for synthesizing silver nanoparticles without the addition of any external reducing or capping agent. The appearance of blackish brown color evidenced the complete synthesis of nanoparticles. The synthesized silver nanoparticles were characterized by UV-vis spectroscopy, scanning electron microscope (SEM), energy dispersive X-ray spectroscopy (EDX), transmission electron microscope (TEM), atomic force microscopy (AFM) and Fourier transforms infrared spectroscopy (FT-IR) analysis. UV-vis absorption profile of the bio-reduced sample elucidated the main peak around 420nm, which correspond to the surface plasmon resonance of silver nanoparticles. SEM and AFM analyses confirmed the morphology of the synthesized nanoparticles. Similarly, particles with a distinctive peak of silver were examined with EDX. The average diameter of silver nanoparticles was about 25nm from Transmission Electron Microscopy (TEM). FTIR spectroscopy scrutinized the involvement of various functional groups during nanoparticle synthesis. The green synthesized nanoparticles presented effective antibacterial activity against pathogenic bacteria than AVLE alone. In-vitro antioxidant assays revealed that silver nanoparticles (AV-AgNPs) exhibited promising antioxidant properties. The nanoparticles also displayed a potent cytotoxic effect against HeLa and MCF-7 cell lines. In conclusion, the results supported the advantages of employing a bio-green approach for developing silver nanoparticles with antimicrobial, antioxidant, and antiproliferative activities in a simple and cost- competitive manner. Copyright © 2017 Elsevier B.V. All rights reserved.

Frequency and time domain three-dimensional inversion of electromagnetic data for a grounded-wire source

NASA Astrophysics Data System (ADS)

Sasaki, Yutaka; Yi, Myeong-Jong; Choi, Jihyang; Son, Jeong-Sul

2015-01-01

We present frequency- and time-domain three-dimensional (3-D) inversion approaches that can be applied to transient electromagnetic (TEM) data from a grounded-wire source using a PC. In the direct time-domain approach, the forward solution and sensitivity were obtained in the frequency domain using a finite-difference technique, and the frequency response was then Fourier-transformed using a digital filter technique. In the frequency-domain approach, TEM data were Fourier-transformed using a smooth-spectrum inversion method, and the recovered frequency response was then inverted. The synthetic examples show that for the time derivative of magnetic field, frequency-domain inversion of TEM data performs almost as well as time-domain inversion, with a significant reduction in computational time. In our synthetic studies, we also compared the resolution capabilities of the ground and airborne TEM and controlled-source audio-frequency magnetotelluric (CSAMT) data resulting from a common grounded wire. An airborne TEM survey at 200-m elevation achieved a resolution for buried conductors almost comparable to that of the ground TEM method. It is also shown that the inversion of CSAMT data was able to detect a 3-D resistivity structure better than the TEM inversion, suggesting an advantage of electric-field measurements over magnetic-field-only measurements.

Characterization of process-induced damage in Cu/low-k interconnect structure by microscopic infrared spectroscopy with polarized infrared light

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

Seki, Hirofumi, E-mail: Hirofumi-Seki@trc.toray.co.jp; Hashimoto, Hideki; Ozaki, Yukihiro

Microscopic Fourier-transform infrared (FT-IR) spectra are measured for a Cu/low-k interconnect structure using polarized IR light for different widths of low-k spaces and Cu lines, and for different heights of Cu lines, on Si substrates. Although the widths of the Cu line and the low-k space are 70 nm each, considerably smaller than the wavelength of the IR light, the FT-IR spectra of the low-k film were obtained for the Cu/low-k interconnect structure. A suitable method was established for measuring the process-induced damage in a low-k film that was not detected by the TEM-EELS (Transmission Electron Microscope-Electron Energy-Loss Spectroscopy) using microscopicmore » IR polarized light. Based on the IR results, it was presumed that the FT-IR spectra mainly reflect the structural changes in the sidewalls of the low-k films for Cu/low-k interconnect structures, and the mechanism of generating process-induced damage involves the generation of Si-OH groups in the low-k film when the Si-CH{sub 3} bonds break during the fabrication processes. The Si-OH groups attract moisture and the OH peak intensity increases. It was concluded that the increase in the OH groups in the low-k film is a sensitive indicator of low-k damage. We achieved the characterization of the process-induced damage that was not detected by the TEM-EELS and speculated that the proposed method is applicable to interconnects with line and space widths of 70 nm/70 nm and on shorter scales of leading edge devices. The location of process-induced damage and its mechanism for the Cu/low-k interconnect structure were revealed via the measurement method.« less

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

Yashchuk, V.V.; Conley, R.; Anderson, E.H.

Verification of the reliability of metrology data from high quality X-ray optics requires that adequate methods for test and calibration of the instruments be developed. For such verification for optical surface profilometers in the spatial frequency domain, a modulation transfer function (MTF) calibration method based on binarypseudo-random (BPR) gratings and arrays has been suggested and and proven to be an effective calibration method for a number of interferometric microscopes, a phase shifting Fizeau interferometer, and a scatterometer. Here we describe the details of development of binarypseudo-random multilayer (BPRML) test samples suitable for characterization of scanning (SEM) and transmission (TEM) electronmore » microscopes. We discuss the results of TEM measurements with the BPRML test samples fabricated from a WiSi{sub 2}/Si multilayer coating with pseudo-randomly distributed layers. In particular, we demonstrate that significant information about the metrological reliability of the TEM measurements can be extracted even when the fundamental frequency of the BPRML sample is smaller than the Nyquist frequency of the measurements. The measurements demonstrate a number of problems related to the interpretation of the SEM and TEM data. Note that similar BPRML testsamples can be used to characterize X-ray microscopes. Corresponding work with X-ray microscopes is in progress.« less

In situ nanomechanical testing of twinned metals in a transmission electron microscope

DOE PAGES

Li, Nan; Wang, Jiangwei; Mao, Scott; ...

2016-04-01

This paper focuses on in situ transmission electron microscope (TEM) characterization to explore twins in face-centered-cubic and body-centered-cubic monolithic metals, and their impact on the overall mechanical performance. Taking advantage of simultaneous nanomechanical deformation and nanoscale imaging using versatile in situ TEM tools, direct correlation of these unique microscopic defects with macroscopic mechanical performance becomes possible. This article summarizes recent evidence to support the mechanisms related to strengthening and plasticity in metals, including nanotwinned Cu, Ni, Al, Au, and others in bulk, thin film, and nanowire forms.

In situ nanomechanical testing of twinned metals in a transmission electron microscope

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

Li, Nan; Wang, Jiangwei; Mao, Scott

This paper focuses on in situ transmission electron microscope (TEM) characterization to explore twins in face-centered-cubic and body-centered-cubic monolithic metals, and their impact on the overall mechanical performance. Taking advantage of simultaneous nanomechanical deformation and nanoscale imaging using versatile in situ TEM tools, direct correlation of these unique microscopic defects with macroscopic mechanical performance becomes possible. This article summarizes recent evidence to support the mechanisms related to strengthening and plasticity in metals, including nanotwinned Cu, Ni, Al, Au, and others in bulk, thin film, and nanowire forms.

Thermophysical ESEM and TEM Characterization of Carbon Fibers CTE, Spectroscopy and Roughness Studies at High Temperatures

NASA Technical Reports Server (NTRS)

Ochoa, Ozden O.

2004-01-01

Accurate determination of the transverse properties of carbon fibers is important for assessment and prediction of local material as well as global structural response of composite components. However the measurements are extremely difficult due to the very small diameters of the fibers (few microns only) and must be conducted within a microscope. In this work, environmental scanning electron microscope (ESEM) and transmission electron microscope (TEM) are used to determine the transverse coefficient of thermal expansion of different carbon fibers as a function of temperature.

Antibacterial and cytotoxic potential of silver nanoparticles synthesized using latex of Calotropis gigantea L.

NASA Astrophysics Data System (ADS)

Rajkuberan, Chandrasekaran; Sudha, Kannaiah; Sathishkumar, Gnanasekar; Sivaramakrishnan, Sivaperumal

2015-02-01

The present study aimed to synthesis silver nanoparticles (AgNPs) in a greener route using aqueous latex extract of Calotropis gigantea L. toward biomedical applications. Initially, synthesis of AgNPs was confirmed through UV-Vis spectroscopy which shows the surface plasmonic resonance peak (SPR) at 420 nm. Fourier transform infrared spectroscopy (FTIR) analysis provides clear evidence that protein fractions present in the latex extract act as reducing and stabilizing bio agents. Energy dispersive X-ray (EDAX) spectroscopy confirms the presence of silver as a major constituent element. X-ray diffractograms displays that the synthesized AgNPs were biphasic crystalline nature. Electron microscopic studies such as Field emission scanning electron microscopic (Fe-SEM) and Transmission electron microscope (TEM) reveals that synthesized AgNPs are spherical in shape with the size range between 5 and 30 nm. Further, crude latex aqueous extract and synthesized AgNPs were evaluated against different bacterial pathogens such as Bacillus cereus, Enterococci sp, Shigella sp, Pseudomonas aeruginosa, Klebsiella pneumonia, Staphylococcus aureus and Escherichia coli. Compared to the crude latex aqueous extract, biosynthesized AgNPs exhibits a remarkable antimicrobial activity. Likewise invitro anticancer study manifests the cytotoxicity value of synthesized AgNPs against tested HeLa cells. The output of this study clearly suggesting that biosynthesized AgNPs using latex of C. gigantea can be used as promising nanomaterial for therapeutic application in context with nanodrug formulation.

Fabrication, Characterization and Cytotoxicity of Spherical-Shaped Conjugated Gold-Cockle Shell Derived Calcium Carbonate Nanoparticles for Biomedical Applications

NASA Astrophysics Data System (ADS)

Kiranda, Hanan Karimah; Mahmud, Rozi; Abubakar, Danmaigoro; Zakaria, Zuki Abubakar

2018-01-01

The evolution of nanomaterial in science has brought about a growing increase in nanotechnology, biomedicine, and engineering fields. This study was aimed at fabrication and characterization of conjugated gold-cockle shell-derived calcium carbonate nanoparticles (Au-CSCaCO3NPs) for biomedical application. The synthetic technique employed used gold nanoparticle citrate reduction method and a simple precipitation method coupled with mechanical use of a Programmable roller-ball mill. The synthesized conjugated nanomaterial was characterized for its physicochemical properties using transmission electron microscope (TEM), field emission scanning electron microscope (FESEM) equipped with energy dispersive X-ray (EDX) and Fourier transform infrared spectroscopy (FTIR). However, the intricacy of cellular mechanisms can prove challenging for nanomaterial like Au-CSCaCO3NPs and thus, the need for cytotoxicity assessment. The obtained spherical-shaped nanoparticles (light-green purplish) have an average diameter size of 35 ± 16 nm, high carbon and oxygen composition. The conjugated nanomaterial, also possesses a unique spectra for aragonite polymorph and carboxylic bond significantly supporting interactions between conjugated nanoparticles. The negative surface charge and spectra absorbance highlighted their stability. The resultant spherical shaped conjugated Au-CSCaCO3NPs could be a great nanomaterial for biomedical applications.

Graphene Dendrimer-stabilized silver nanoparticles for detection of methimazole using Surface-enhanced Raman scattering with computational assignment

NASA Astrophysics Data System (ADS)

Saleh, Tawfik A.; Al-Shalalfeh, Mutasem M.; Al-Saadi, Abdulaziz A.

2016-08-01

Graphene functionalized with polyamidoamine dendrimer, decorated with silver nanoparticles (G-D-Ag), was synthesized and evaluated as a substrate with surface-enhanced Raman scattering (SERS) for methimazole (MTZ) detection. Sodium borohydride was used as a reducing agent to cultivate silver nanoparticles on the dendrimer. The obtained G-D-Ag was characterized by using UV-vis spectroscopy, scanning electron microscope (SEM), high-resolution transmission electron microscope (TEM), Fourier-transformed infrared (FT-IR) and Raman spectroscopy. The SEM image indicated the successful formation of the G-D-Ag. The behavior of MTZ on the G-D-Ag as a reliable and robust substrate was investigated by SERS, which indicated mostly a chemical interaction between G-D-Ag and MTZ. The bands of the MTZ normal spectra at 1538, 1463, 1342, 1278, 1156, 1092, 1016, 600, 525 and 410 cm-1 were enhanced due to the SERS effect. Correlations between the logarithmical scale of MTZ concentrations and SERS signal intensities were established, and a low detection limit of 1.43 × 10-12 M was successfully obtained. The density functional theory (DFT) approach was utilized to provide reliable assignment of the key Raman bands.

Fabrication of magnetic water-soluble hyperbranched polyol functionalized graphene oxide for high-efficiency water remediation

PubMed Central

Hu, Lihua; Li, Yan; Zhang, Xuefei; Wang, Yaoguang; Cui, Limei; Wei, Qin; Ma, Hongmin; Yan, Liangguo; Du, Bin

2016-01-01

Magnetic water-soluble hyperbranched polyol functionalized graphene oxide nanocomposite (MWHPO-GO) was successfully prepared and applied to water remediation in this paper. MWHPO-GO was characterized by Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), thermogravimetric analysis (TGA), magnetization curve, zeta potential, scanning electron microscope (SEM) and transmission electron microscope (TEM) analyses. MWHPO-GO exhibited excellent adsorption performance for the removal of synthetic dyes (methylene blue (MB) and methyl violet (MV)) and heavy metal (Pb(II)). Moreover, MWHPO-GO could be simply recovered from water with magnetic separation. The pseudo-second order equation and the Langmuir model exhibited good correlation with the adsorption kinetic and isotherm data, respectively, for these three pollutants. The thermodynamic results (ΔG < 0, ΔH < 0, ΔS < 0) implied that the adsorption process of MB, MV and Pb(II) was feasible, exothermic and spontaneous in nature. A possible adsorption mechanism has been proposed where π-π stacking interactions, H-bonding interaction and electrostatic attraction dominated the adsorption of MB/MV and chelation and electrostatic attraction dominated the adsorption of Pb(II). In addition, the excellent reproducibility endowed MWHPO-GO with the potential for application in water remediation. PMID:27354318

Green synthesis of silver nanoparticle and silver based chitosan bionanocomposite using stem extract of Saccharum officinarum and assessment of its antibacterial activity

NASA Astrophysics Data System (ADS)

Paulkumar, Kanniah; Gnanajobitha, Gnanadhas; Vanaja, Mahendran; Pavunraj, Manickam; Annadurai, Gurusamy

2017-09-01

Synthesis of nanoparticles and nanocomposites using green route is a major focus of modern nanotechnology. Herein we demonstrate the synthesis of silver nanoparticle and silver based chitosan bionanocomposite using the stem extract of Saccharum officinarum. The absorbance peak at 460 nm in the UV-Vis spectrum reveals the synthesis of silver nanoparticles using the stem extract of Saccharum officinarum. The size of the synthesized silver nanoparticle was in the range of 10-60 nm obtained from transmission electron microscope (TEM) analysis. The presence of silver nanoparticles on the chitosan suspension was identified by scanning electron microscope (SEM) and energy dispersive x-ray spectroscopy (EDS). The presence of possible functional group involved in the reduction of silver metal ions into silver nanoparticles was identified by Fourier transform infrared spectroscopy (FTIR) analysis. The antibacterial activity of the synthesized silver based chitosan bionanocomposite was evaluated against Bacillus subtilis (MTCC 3053), Klebsiella planticola (MTCC 2277), Streptococcus faecalis (ATCC 8043), Pseudomonas aeruginosa (ATCC 9027) and Escherichia coli (ATCC 8739). The antibacterial activity of silver based chitosan bionanocomposite has remarkable scope in medicine, food packaging, textile and pharmaceuticals.

High-efficiency and conveniently recyclable photo-catalysts for dye degradation based on urchin-like CuO microparticle/polymer hybrid composites

NASA Astrophysics Data System (ADS)

Liu, Xiong; Cheng, Yuming; Li, Xuefeng; Dong, Jinfeng

2018-05-01

In this work, we developed a new type of photo-catalysts composed of the urchin-like cupric oxide (CuO) microparticle and polyvinylidene fluoride (PVDF) hybrid composites by the convenient organic-inorganic hybrid strategy, which show high-efficiency and conveniently recyclable for dye degradation including methylene blue (MB), Congo red (CR), and malachite green (MG) by visible light irradiation. The micro-structural characteristics of urchin-like CuO microparticles are crucial and dominant over the photo-degrading efficiency of hybrid catalyst because of their highly exposed {0 0 2} facet and larger specific surface area. Simultaneously, the intrinsic porous framework of PVDF membrane not only remains the excellent photo-catalytic activity of urchin-like CuO microparticles but also facilitates the enrichment of dyes on the membrane, and thereby synergistically contributing to the photo-catalytic efficiency. The microstructures of both urchin-like CuO microparticles and hybrid catalysts are systematically characterized by various techniques including scanning electron microscopy (SEM), transmission electron microscope (TEM), high-resolution transmission electron microscope (HRTEM), powder X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), Fourier transform infrared spectroscopy (FTIR), and nitrogen adsorption/desorption isotherms, which evidently support the mentioned mechanism.

Synthesis of hydroxyapatite nanoparticles by a novel ultrasonic assisted with mixed hollow sphere template method

NASA Astrophysics Data System (ADS)

Gopi, D.; Indira, J.; Kavitha, L.; Sekar, M.; Mudali, U. Kamachi

Hydroxyapatite (HAP) is the main inorganic component of bone material and is widely used in various biomedical applications due to its excellent bioactivity and biocompatibility. In this paper, we have reported the synthesis of hydroxyapatite nanoparticles by a novel ultrasonic assisted mixed template directed method. In this method glycine-acrylic acid (GLY-AA) hollow spheres were used as an organic template which could be prepared by mixing of glycine with acrylic acid. The as-synthesized HAP nanoparticles were characterized by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), scanning electron microscope (SEM) and tunnelling electron microscope (TEM) to investigate the nature of bonding, crystallinity, size and shape. The thermal stability of as-synthesized nanoparticles was also investigated by the thermo gravimetric analysis (TGA). The effect of ultrasonic irradiation time on the crystallinity and size of the HAP nanoparticles in presence of glycine-acrylic acid hollow spheres template were investigated. From the inspection of the above results it is confirmed that the crystallinity and size of the HAP nanoparticles decrease with increasing ultrasonic irradiation time. Hence the proposed synthesis strategy provides a facile pathway to obtain nano sized HAP with high quality, suitable size and morphology.

Graphene Dendrimer-stabilized silver nanoparticles for detection of methimazole using Surface-enhanced Raman scattering with computational assignment

PubMed Central

Saleh, Tawfik A.; Al-Shalalfeh, Mutasem M.; Al-Saadi, Abdulaziz A.

2016-01-01

Graphene functionalized with polyamidoamine dendrimer, decorated with silver nanoparticles (G-D-Ag), was synthesized and evaluated as a substrate with surface-enhanced Raman scattering (SERS) for methimazole (MTZ) detection. Sodium borohydride was used as a reducing agent to cultivate silver nanoparticles on the dendrimer. The obtained G-D-Ag was characterized by using UV-vis spectroscopy, scanning electron microscope (SEM), high-resolution transmission electron microscope (TEM), Fourier-transformed infrared (FT-IR) and Raman spectroscopy. The SEM image indicated the successful formation of the G-D-Ag. The behavior of MTZ on the G-D-Ag as a reliable and robust substrate was investigated by SERS, which indicated mostly a chemical interaction between G-D-Ag and MTZ. The bands of the MTZ normal spectra at 1538, 1463, 1342, 1278, 1156, 1092, 1016, 600, 525 and 410 cm−1 were enhanced due to the SERS effect. Correlations between the logarithmical scale of MTZ concentrations and SERS signal intensities were established, and a low detection limit of 1.43 × 10−12 M was successfully obtained. The density functional theory (DFT) approach was utilized to provide reliable assignment of the key Raman bands. PMID:27572919

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.

Enhanced capacitance and rate capability of graphene/polypyrrole composite as electrode material for supercapacitors

NASA Astrophysics Data System (ADS)

Zhang, Dacheng; Zhang, Xiong; Chen, Yao; Yu, Peng; Wang, Changhui; Ma, Yanwei

Graphene and polypyrrole composite (PPy/GNS) is synthesized via in situ polymerization of pyrrole monomer in the presence of graphene under acid conditions. The structure and morphology of the composite are characterized by X-ray diffraction (XRD), Raman spectroscopy, Fourier transform infrared spectrometer (FTIR), X-rays photoelectron spectroscopy (XPS) and transmission electron microscope (TEM). It is found that a uniform composite is formed with polypyrrole being homogeneously surrounded by graphene nanosheets (GNS). The composite is a promising candidate for supercapacitors to have higher specific capacitance, better rate capability and cycling stability than those of pure polypyrrole. The specific capacitance of PPy/GNS composite based on the three-electrode cell configuration is as high as 482 F g -1 at a current density of 0.5 A g -1. After 1000 cycles, the attenuation of the specific capacitance is less than 5%, indicating that composite has excellent cycling performance.

Sonochemically synthesized MnO2 nanoparticles as electrode material for supercapacitors.

PubMed

Gnana Sundara Raj, Balasubramaniam; Asiri, Abdullah M; Qusti, Abdullah H; Wu, Jerry J; Anandan, Sambandam

2014-11-01

In this study, manganese oxide (MnO2) nanoparticles were synthesized by sonochemical reduction of KMnO4 using polyethylene glycol (PEG) as a reducing agent as well as structure directing agent under room temperature in short duration of time and characterized by powder X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), Scanning electron microscope (SEM), Transmission electron microscopy (TEM) and Brunauer-Emmett-Teller (BET) analysis. A supercapacitor device constructed using the ultrasonically-synthesized MnO2 nanoparticles showed maximum specific capacitance (SC) of 282Fg(-1) in the presence of 1M Ca(NO3)2 as an electrolyte at a current density of 0.5mAcm(-2) in the potential range from 0.0 to 1.0V and about 78% of specific capacitance was retained even after 1000 cycles indicating its high electrochemical stability. Copyright © 2013 Elsevier B.V. All rights reserved.

Synthesis, characterization and catalytic activity of silver nanoparticles using Tribulus terrestris leaf extract.

PubMed

Ashokkumar, S; Ravi, S; Kathiravan, V; Velmurugan, S

2014-01-01

Biomediated silver nanoparticles were synthesized with the aid of an eco-friendly biomaterial, namely, aqueous Tribulus terrestris extract. Silver nanoparticles were synthesized using a rapid, single step, and completely green biosynthetic method employing aqueous T. terrestris leaf extracts as both the reducing and capping agent. Silver ions were rapidly reduced by aqueous T. terrestris leaf extracts, leading to the formation of highly crystalline silver nanoparticles. An attempt has been made and formation of the silver nanoparticles was verified by surface plasmon spectra using an UV-vis (Ultra violet), spectrophotometer. Morphology and crystalline structure of the prepared silver nanoparticles were characterized by TEM (Transmission Electron Microscope) and XRD (X-ray Diffraction), techniques, respectively. FT-IR (Fourier Transform Infrared), analysis suggests that the obtained silver nanoparticles might be stabilized through the interactions of carboxylic groups, carbonyl groups and the flavonoids present in the T. terrestris extract. Copyright © 2013 Elsevier B.V. All rights reserved.

Reusable magnetic nanobiocatalyst for synthesis of silver and gold nanoparticles.

PubMed

Mazumder, Jahirul Ahmed; Ahmad, Razi; Sardar, Meryam

2016-12-01

In the present work, we describe a simple procedure for the biosynthesis of nanosilver and gold by the reduction of silver nitrate and auric chloride respectively using a nanobiocatalyst. The nanobiocatalyst was prepared by covalent coupling of alpha amylase on (3-aminopropyl)triethoxysilane (APTES) modified iron oxide magnetic nanoparticles. The nanobiocatalyst retains 77% of its activity as compared to free alpha amylase. The nanobiocatalyst can be used up to three consecutive cycles for the synthesis of nano silver and gold. The biosynthesized nanoparticles after each cycle were characterized by UV-vis spectrophotometer, Dynamic Light Spectroscopy (DLS), Transmission Electron Microscope (TEM), X-ray powder diffraction (XRD), and Fourier transform infrared spectroscopy (FTIR). Silver and gold nanoparticles of same morphology and dimensions were formed in each cycle. The procedure for synthesis of nanoparticles using an immobilized enzyme is eco-friendly and can be used repeatedly. Copyright © 2016 Elsevier B.V. All rights reserved.

Optimization and stabilization of gold nanoparticles by using herbal plant extract with microwave heating

NASA Astrophysics Data System (ADS)

Yasmin, Akbar; Ramesh, Kumaraswamy; Rajeshkumar, Shanmugam

2014-04-01

In this study, we have synthesized the gold nanoparticles by using Hibiscus rosa-sinensis, a medicinal plant. The gold nanoparticles were synthesized rapidly by the involvement of microwave heating. By changing of plant extract concentration, gold solution concentration, microwave heating time and power of microwave heating the optimized condition was identified. The surface Plasmon resonance found at 520 nm confirmed the gold nanoparticles synthesis. The spherical sized nanoparticles in the size range of 16-30 nm were confirmed by Transmission Electron Microscope (TEM). The stability of the nanoparticles is very well proved in the invitro stability tests. The biochemical like alkaloids and flavonoids play a vital role in the nanoparticles synthesis was identified using the Fourier Transform Infrared Spectroscopy (FTIR). Combining the phytochemical and microwave heating, the rapid synthesis of gold nanoparticles is the novel process for the medically applicable gold nanoparticles production.

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

Padmaja, S.; Jayakumar, S., E-mail: s_jayakumar_99@yahoo.com; Balaji, R.

Cadmium Sulphide (CdS) nanoparticles were reinforced in Poly(ethylene Oxide) (PEO) and Poly(methyl methacrylate) (PMMA) matrices by in situ technique. The presence of CdS in PEO and PMMA matrix was confirmed using X-ray photoelectron spectroscopy (XPS). Fourier Transform Infrared spectroscopy (FTIR) analysis disclosed the co-ordination of CdS in the matrices. Thermal analysis of the nanocomposites was carried out using Differential Scanning calorimetric studies (DSC). The optical studies using UV–vis spectroscopy were carried out to find the band gap of the materials and the absorption onset. The CdS particle size in the matrices was found by Effective Mass Approximation (EMA) model usingmore » the band gap values and was confirmed by TEM studies. The surface trapped emissions of the nanocomposites were observed from the photoluminescence (PL) spectra. The distribution of CdS particles in the polymer matrices were presented by Atomic force microscopic studies (AFM).« less

Mussel inspired polymerized P(TA-TETA) for facile functionalization of carbon nanotube

NASA Astrophysics Data System (ADS)

Si, Shuxian; Gao, Tingting; Wang, Junhao; Liu, Qinze; Zhou, Guowei

2018-03-01

This article describes a novel and effective approach for non-covalent modification of carbon nanotube (CNT) via the mussel inspired polymerization of tannic acid (TA) and triethylenetetramine (TETA) and subsequent surface initiated atom transfer radical polymerization (SI-ATRP). Fourier transform infrared spectroscopy (FT-IR), thermo-gravimetric analysis (TGA), transmission electron microscope (TEM), X-ray photoelectron spectroscopy (XPS) and photograph were used to study the successful preparation of polymer brush grafted CNT (CNT-P(TA-TETA)-PDMAEMA) composite as well as the pH-responsive behavior of the composite. Furthermore, by amine protonation and in situ reduction, gold nanoparticles were successfully uploaded and the catalytic property of CNT-P(TA-TETA)-PDMAEMA/Au was investigated. We believe that the surface functionalization strategy can be extended to graphene and other substrates, and the surface properties can be regulated by grafting polymer brushes with different functionalities.

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

V Yashchuk; R Conley; E Anderson

Verification of the reliability of metrology data from high quality X-ray optics requires that adequate methods for test and calibration of the instruments be developed. For such verification for optical surface profilometers in the spatial frequency domain, a modulation transfer function (MTF) calibration method based on binary pseudo-random (BPR) gratings and arrays has been suggested [1] and [2] and proven to be an effective calibration method for a number of interferometric microscopes, a phase shifting Fizeau interferometer, and a scatterometer [5]. Here we describe the details of development of binary pseudo-random multilayer (BPRML) test samples suitable for characterization of scanningmore » (SEM) and transmission (TEM) electron microscopes. We discuss the results of TEM measurements with the BPRML test samples fabricated from a WiSi2/Si multilayer coating with pseudo-randomly distributed layers. In particular, we demonstrate that significant information about the metrological reliability of the TEM measurements can be extracted even when the fundamental frequency of the BPRML sample is smaller than the Nyquist frequency of the measurements. The measurements demonstrate a number of problems related to the interpretation of the SEM and TEM data. Note that similar BPRML test samples can be used to characterize X-ray microscopes. Corresponding work with X-ray microscopes is in progress.« less

Optimising electron microscopy experiment through electron optics simulation.

PubMed

Kubo, Y; Gatel, C; Snoeck, E; Houdellier, F

2017-04-01

We developed a new type of electron trajectories simulation inside a complete model of a modern transmission electron microscope (TEM). Our model incorporates the precise and real design of each element constituting a TEM, i.e. the field emission (FE) cathode, the extraction optic and acceleration stages of a 300kV cold field emission gun, the illumination lenses, the objective lens, the intermediate and projection lenses. Full trajectories can be computed using magnetically saturated or non-saturated round lenses, magnetic deflectors and even non-cylindrical symmetry elements like electrostatic biprism. This multi-scale model gathers nanometer size components (FE tip) with parts of meter length (illumination and projection systems). We demonstrate that non-trivial TEM experiments requiring specific and complex optical configurations can be simulated and optimized prior to any experiment using such model. We show that all the currents set in all optical elements of the simulated column can be implemented in the real column (I2TEM in CEMES) and used as starting alignment for the requested experiment. We argue that the combination of such complete electron trajectory simulations in the whole TEM column with automatic optimization of the microscope parameters for optimal experimental data (images, diffraction, spectra) allows drastically simplifying the implementation of complex experiments in TEM and will facilitate the development of advanced use of the electron microscope in the near future. Copyright © 2017 Elsevier B.V. All rights reserved.

The binary complex of poly(PEGMA-co-MAA) hydrogel and PLGA nanoparticles as a novel oral drug delivery system for ibuprofen delivery.

PubMed

Shang, Qing; Huang, Sijin; Zhang, Aixin; Feng, Jia; Yang, Song

2017-11-01

To improve the bioavailability of ibuprofen (IBU), we developed a novel binary complex of poly(PEGMA-co-MAA) hydrogel and IBU-loaded PLGA nanoparticles (IBU-PLGA NPs@hydrogels) as an oral intestinal targeting drug delivery system (OIDDS). The IBU-loaded PLGA NPs and pH-sensitive hydrogels were obtained via the solvent evaporation method and radical polymerization, respectively. The final OIDDS was obtained by immersing the hydrogel chips in the IBU-loaded PLGA NPs solutions (pH 7.4) for 3 d. The size distribution and morphology of cargo-free NPs were studied by laser granularity analyzer and transmission electron microscope (TEM). The inner structures of the pH-sensitive hydrogel chips were observed with an S-4800 scanning electron microscope (SEM). The distribution states of IBU in the OIDDS were also studied with X-ray diffraction (XRD) and differential scanning calorimetry (DSC). TEM photographs illustrated that the PLGA NPs had a round shape with an average diameter about 100 nm. Fourier transform infrared spectrum (FTIR) confirmed the synthesis of poly(PEGMA-co-MAA) hydrogel. The SEM picture showed that the final hydrogel had 3D net-work structures. Moreover, the poly(PEGMA-co-MAA) hydrogel showed an excellent pH-sensitivity. The XRD and DSC curves suggested that IBU distributed in the OIDDS with an amorphous state. The cumulated release profiles indicated that the final OIDDS could release IBU in alkaline environment (e.g. intestinal tract) at a sustained manner. Therefore, the novel OIDDS could improve the oral bioavailability of IBU, and had a potential application in drug delivery.

Improvement on controllable fabrication of streptavidin-modified three-layer core-shell Fe3O4@SiO2@Au magnetic nanocomposites with low fluorescence background.

PubMed

Jiang, Hongrong; Zeng, Xin; Xi, Zhijiang; Liu, Ming; Li, Chuanyan; Li, Zhiyang; Jin, Lian; Wang, Zhifei; Deng, Yan; He, Nongyue

2013-04-01

In present study, we put forward an approach to prepare three-layer core-shell Fe3O4@SiO2@Au magnetic nanocomposites via the combination of self-assembling, seed-mediated growing and multi-step chemical reduction. The Fe3O4@SiO2@Au magnetic nanocomposites were analyzed and characterized by transmission electron microscope (TEM), scanning electronic microscope (SEM), energy dispersive spectrometer analysis (EDS), Fourier transform infrared spectroscopy (FT-IR), vibrating sample magnetometer (VSM), and ultraviolet and visible spectrophotometer (UV-Vis). TEM and SEM characterizations showed that the FeO4@SiO2@Au nanocomposites were obtained successfully with three-layer structures, especially a layer of thin, smooth and continuous gold shell. The average diameter of Fe3O4@SiO2@Au nanocomposites was about 600 nm and an excellent dispersity was observed for the as-prepared nanoparticles. EDS characterizations demonstrated that the nanocomposites contained three elements of the precursors, Fe, Si, and Au. Furthermore, FT-IR showed that the silica and gold shell were coated successfully. UV-Vis and VSM characterizations showed that the Fe3O4@SiO2@Au nanocomposites exhibited good optical and magnetic property, and the saturation magnetization was 25.76 emu/g. In conclusion, the Fe3O4@SiO2@Au magnetic nanocomposites with three-layer core-shell structures were prepared. Furthermore, Fe3O4@SiO2@Au magnetic nanocomposites were modified with streptavidin (SA) successfully, and it was validated that they performed low fluorescence background, suggesting that they should have good applications especially in bioassay based on fluorescence detection through bonding the biotinylated fluorescent probes.

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

Yashchuk, Valeriy V; Conley, Raymond; Anderson, Erik H.

We discuss the results of SEM and TEM measurements with the BPRML test samples fabricated from a BPRML (WSi2/Si with fundamental layer thickness of 3 nm) with a Dual Beam FIB (focused ion beam)/SEM technique. In particular, we demonstrate that significant information about the metrological reliability of the TEM measurements can be extracted even when the fundamental frequency of the BPRML sample is smaller than the Nyquist frequency of the measurements. The measurements demonstrate a number of problems related to the interpretation of the SEM and TEM data. Note that similar BPRML test samples can be used to characterize x-raymore » microscopes. Corresponding work with x-ray microscopes is in progress.« less

Green way genesis of silver nanoparticles using multiple fruit peels waste and its antimicrobial, anti-oxidant and anti-tumor cell line studies

NASA Astrophysics Data System (ADS)

Naganathan, Kiruthika; Thirunavukkarasu, Somanathan

2017-04-01

Green synthesis of silver nanoparticles (SNP) opens a new path to kill and prevent various infectious diseases and also tumor. In this study, we have synthesized silver nanoparticles using multiple fruit peel waste (pomegranate, orange, banana and apple (POBA)). The primarily nanoparticles formation has been confirmed by the color change. The synthesized SNP were analyzed by various physicochemical techniques such as UV- Visible spectroscopy, x-ray diffraction (XRD), fourier transform infra red (FT-IR) spectroscopy and transmission electron microscope (TEM). The formation of SNP was confirmed by its absorbance peak observed at 430 nm in UV-Visible spectrum. Further, the obtained SNP were identified by XRD and TEM, respectively to know the crystalline nature and size and shape of the particles. The activities of SNP were checked with human pathogens (Salmonella, E.coli and Pseudomonas), plant pathogen (Fusarium) and marine pathogen (Aeromonas hydrophila) and also studied the scavenging effect and anticancer properties against MCF-7 cell lines. This studies proves that the SNP prepared from fruit waste peel extract approach appears extremely fast, cost efficient, eco-friendly and alternative for conventional methods of SNP synthesis to promote the usage of these nanoparticles in medicinal application.

Organic-Inorganic Hydrophobic Nanocomposite Film with a Core-Shell Structure

PubMed Central

Liu, Peng; Chen, Ying; Yu, Zhiwu

2016-01-01

A method to prepare novel organic-inorganic hydrophobic nanocomposite films was proposed by a site-specific polymerization process. The inorganic part, the core of the nanocomposite, is a ternary SiO2–Al2O3–TiO2 nanoparticles, which is grafted with methacryloxy propyl trimethoxyl silane (KH570), and wrapped by fluoride and siloxane polymers. The synthesized samples are characterized by transmission electron microscopy (TEM), Fourier transform infrared (FTIR) spectrscopy, X-ray diffractometry (XRD), contact angle meter (CA), and scanning electron microscope (SEM). The results indicate that the novel organic-inorganic hydrophobic nanocomposite with a core-shell structure was synthesized successfully. XRD analysis reveals the nanocomposite film has an amorphous structure, and FTIR analysis indicates the nanoparticles react with a silane coupling agent (methacryloxy propyl trimethoxyl silane KH570). Interestingly, the morphology of the nanoparticle film is influenced by the composition of the core. Further, comparing with the film synthesized by silica nanoparticles, the film formed from SiO2–Al2O3–TiO2 nanoparticles has higher hydrophobic performance, i.e., the contact angle is greater than 101.7°. In addition, the TEM analysis reveals that the crystal structure of the particles can be changed at high temperatures. PMID:28774141

Nanoscale characterization of the thermal interface resistance of a heat-sink composite material by in situ TEM.

PubMed

Kawamoto, Naoyuki; Kakefuda, Yohei; Mori, Takao; Hirose, Kenji; Mitome, Masanori; Bando, Yoshio; Golberg, Dmitri

2015-11-20

We developed an original method of in situ nanoscale characterization of thermal resistance utilizing a high-resolution transmission electron microscope (HRTEM). The focused electron beam of the HRTEM was used as a contact-free heat source and a piezo-movable nanothermocouple was developed as a thermal detector. This method has a high flexibility of supplying thermal-flux directions for nano/microscale thermal conductivity analysis, and is a powerful way to probe the thermal properties of complex or composite materials. Using this method we performed reproducible measurements of electron beam-induced temperature changes in pre-selected sections of a heat-sink α-Al(2)O(3)/epoxy-based resin composite. Observed linear behavior of the temperature change in a filler reveals that Fourier's law holds even at such a mesoscopic scale. In addition, we successfully determined the thermal resistance of the nanoscale interfaces between neighboring α-Al(2)O(3) fillers to be 1.16 × 10(-8) m(2)K W(-1), which is 35 times larger than that of the fillers themselves. This method that we have discovered enables evaluation of thermal resistivity of composites on the nanoscale, combined with the ultimate spatial localization and resolution sample analysis capabilities that TEM entails.

The Potential Protective Effects of 2-aminoethyl Diphenylborinate against Inner Ear Acoustic Trauma: Experimental Study Using Transmission and Scanning Electron Microscopy.

PubMed

Kaymakçı, Mustafa; Acar, Mustafa; Burukoglu, Dilek; Kutlu, Hatice Mehtap; Shojaolsadati, Paria; Cingi, Cemal; Bayar Muluk, Nuray

2015-04-01

In this prospective experimental study, we investigated the preventive effects of 2-aminoethyl diphenylborinate (2-APB) in rats exposed to acoustic trauma (AT). Light microscopic, transmission electron microscopic (TEM), and scanning electron microscopic (SEM) examinations were performed. Eighteen healthy Wistar albino rats were divided into the following three groups: groups 1 (control), 2 (AT), and 3 (AT+APB). The rats in groups 2 and 3 were exposed to AT; in group 3 rats, 2-APB at 2 mg/kg was also administered, initially transperitoneally, after 10 min. During the light microscopic, TEM, and SEM examinations, the structures of the cochlear hair cells, stereocilia, and Deiter's cells were normal in the control group. In the AT group, the organ of Corti and proximate structures were damaged according to the light microscopic examination. During the TEM examination, intense cellular damage and stereocilia loss were detected, while during the SEM examination, extensive damage and stereocilia loss were observed. Decreased damage with preserved cochlear structure was detected during the light microscopic examination in the AT+APB group than in the AT group. During the TEM and SEM examinations, although stereocilia loss occurred in the AT+APB group, near-normal cell, cilia, and tectorial membrane structures were also observed in the AT+APB group compared with the AT group. 2-APB may have protective effects against AT damage of the cochlea. The main mechanism underlying this effect is the inhibition of the vasoconstriction of the cochlear spiral modiolar artery, thereby improving cochlear blood flow. We conclude that 2-APB may also be effective if used immediately following AT.

Fourier-space TEM reconstructions with symmetry adapted functions for all rotational point groups.

PubMed

Trapani, Stefano; Navaza, Jorge

2013-05-01

A general-purpose and simple expression for the coefficients of symmetry adapted functions referred to conveniently oriented symmetry axes is given for all rotational point groups. The expression involves the computation of reduced Wigner-matrix elements corresponding to an angle specific to each group and has the computational advantage of leading to Fourier-space TEM (transmission electron microscopy) reconstruction procedures involving only real valued unknowns. Using this expression, a protocol for ab initio view and center assignment and reconstruction so far used for icosahedral particles has been tested with experimental data in other point groups. Copyright © 2013 Elsevier Inc. All rights reserved.

Electron tomography of whole cultured cells using novel transmission electron imaging technique.

PubMed

Okumura, Taiga; Shoji, Minami; Hisada, Akiko; Ominami, Yusuke; Ito, Sukehiro; Ushiki, Tatsuo; Nakajima, Masato; Ohshima, Takashi

2018-01-01

Since a three-dimensional (3D) cellular ultrastructure is significant for biological functions, it has been investigated using various electron microscopic techniques. Although transmission electron microscopy (TEM)-based techniques are traditionally used, cells must be embedded in resin and sliced into ultrathin sections in sample preparation processes. Block-face observation using a scanning electron microscope (SEM) has also been recently applied to 3D observation of cellular components, but this is a destructive inspection and does not allow re-examination. Therefore, we developed electron tomography using a transmission electron imaging technique called Plate-TEM. With Plate-TEM, the cells cultured directly on a scintillator plate are inserted into a conventional SEM equipped with a Plate-TEM observation system, and their internal structures are observed by detecting scintillation light produced by electrons passing through the cells. This technology has the following four advantages. First, the cells cultured on the plate can be observed at electron-microscopic resolution since they remain on the plate. Second, both surface and internal information can be obtained simultaneously by using electron- and photo-detectors, respectively, because a Plate-TEM detector is installed in an SEM. Third, the cells on the scintillator plate can also be inspected using light microscopy because the plate has transparent features. Finally, correlative observation with other techniques, such as conventional TEM, is possible after Plate-TEM observation because Plate-TEM is a non-destructive analysis technique. We also designed a sample stage to tilt the samples for tomography with Plate-TEM, by which 3D organization of cellular structures can be visualized as a whole cell. In the present study, Mm2T cells were investigated using our tomography system, resulting in 3D visualization of cell organelles such as mitochondria, lipid droplets, and microvilli. Correlative observations with various imaging techniques were also conducted by successive observations with light microscopy, SEM, Plate-TEM, and conventional TEM. Consequently, the Plate-TEM tomography technique encourages understanding of cellular structures at high resolution, which can contribute to cellular biological research. Copyright © 2017 Elsevier Ltd. All rights reserved.

Fourier plane imaging microscopy

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

Dominguez, Daniel, E-mail: daniel.dominguez@ttu.edu; Peralta, Luis Grave de; Nano Tech Center, Texas Tech University, Lubbock, Texas 79409

We show how the image of an unresolved photonic crystal can be reconstructed using a single Fourier plane (FP) image obtained with a second camera that was added to a traditional compound microscope. We discuss how Fourier plane imaging microscopy is an application of a remarkable property of the obtained FP images: they contain more information about the photonic crystals than the images recorded by the camera commonly placed at the real plane of the microscope. We argue that the experimental results support the hypothesis that surface waves, contributing to enhanced resolution abilities, were optically excited in the studied photonicmore » crystals.« less

Interaction of electrons with light metal hydrides in the transmission electron microscope.

PubMed

Wang, Yongming; Wakasugi, Takenobu; Isobe, Shigehito; Hashimoto, Naoyuki; Ohnuki, Somei

2014-12-01

Transmission electron microscope (TEM) observation of light metal hydrides is complicated by the instability of these materials under electron irradiation. In this study, the electron kinetic energy dependences of the interactions of incident electrons with lithium, sodium and magnesium hydrides, as well as the constituting element effect on the interactions, were theoretically discussed, and electron irradiation damage to these hydrides was examined using in situ TEM. The results indicate that high incident electron kinetic energy helps alleviate the irradiation damage resulting from inelastic or elastic scattering of the incident electrons in the TEM. Therefore, observations and characterizations of these materials would benefit from increased, instead decreased, TEM operating voltage. © The Author 2014. Published by Oxford University Press on behalf of The Japanese Society of Microscopy. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

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

Yashchuk, Valeriy V; Conley, Raymond; Anderson, Erik H

Verification of the reliability of metrology data from high quality x-ray optics requires that adequate methods for test and calibration of the instruments be developed. For such verification for optical surface profilometers in the spatial frequency domain, a modulation transfer function (MTF) calibration method based on binary pseudo-random (BPR) gratings and arrays has been suggested [Proc. SPIE 7077-7 (2007), Opt. Eng. 47(7), 073602-1-5 (2008)} and proven to be an effective calibration method for a number of interferometric microscopes, a phase shifting Fizeau interferometer, and a scatterometer [Nucl. Instr. and Meth. A 616, 172-82 (2010)]. Here we describe the details ofmore » development of binary pseudo-random multilayer (BPRML) test samples suitable for characterization of scanning (SEM) and transmission (TEM) electron microscopes. We discuss the results of TEM measurements with the BPRML test samples fabricated from a WiSi2/Si multilayer coating with pseudo randomly distributed layers. In particular, we demonstrate that significant information about the metrological reliability of the TEM measurements can be extracted even when the fundamental frequency of the BPRML sample is smaller than the Nyquist frequency of the measurements. The measurements demonstrate a number of problems related to the interpretation of the SEM and TEM data. Note that similar BPRML test samples can be used to characterize x-ray microscopes. Corresponding work with x-ray microscopes is in progress.« less

Size determination of Acipenser ruthenus spermatozoa in different types of electron microscopy.

PubMed

Psenicka, Martin; Tesarová, Martina; Tesitel, Jakub; Nebesárová, Jana

2010-07-01

In this study three types of scanning electron microscopes were used for the size determination of spermatozoa of sterlet Acipenser ruthenus - high vacuum scanning electron microscope (SEM, JEOL 6300), environmental scanning electron microscope (ESEM, Quanta 200 FEG), field emission scanning electron microscope (FESEM, JEOL 7401F) with cryoattachment Alto 2500 (Gatan) and transmission electron microscope (TEM, JEOL 1010). The use of particular microscopes was tied with different specimen preparation techniques. The aim of this study was to evaluate to what degree the type of used electron microscope can influence the size of different parts of spermatozoa. For high vacuum SEM the specimen was prepared using two slightly different procedures. After chemical fixation with 2.5% glutaraldehyde in 0.1M phosphate buffer and post-fixation by 1% osmium tetroxide, the specimen was dehydrated by acetone series and dried either by critical point method or by means of t-butylalcohol. For ESEM fresh, unfixed material was used, which was dropped on microscopic copper grids. In FESEM working in cryo-mode the specimen was observed in a frozen state. Ultrathin sections from chemically fixed and Epon embedded specimens were prepared for TEM observation. Distinct parts of sterlet spermatozoa were measured in each microscope and the data obtained was statistically processed. Results confirmed that the classical chemical procedure of specimen preparation for SEM including critical point drying method led to a significant contraction of all measured values, which could deviate up to 30% in comparison with values measured on the fresh chemically untreated specimen in ESEM. Surprisingly sperm dimensions determinated on ultrathin sections by TEM are comparable with values obtained in ESEM or FESEM. Copyright 2010 Elsevier Ltd. All rights reserved.

Ultrastructural changes in tracheal epithelial cells exposed to oxygen

NASA Technical Reports Server (NTRS)

Philpott, D. E.; Harrison, G. A.; Turnbill, C.; Black, S.

1977-01-01

White albino rats were sacrificed after 24, 36, 48, 72, and 96 h of exposure to 100% O2 at 1 atm. Tissue was prepared for the scanning electron microscope (SEM) by Critical Point Drying and for the transmission electron microscope (TEM) by plastic embedding. Scanning microscopy showed a loss of microvilli after 48 h of exposure. Cilia appeared relatively normal with SEM, but TEM revealed changes in the outer membrane. In TEM, nonciliated cells appeared swollen and often encroached on the ciliated cells. A heavy mucous blanket remained even after processing. All the changes observed that are induced by oxygen exposure contribute to mucostasis, reducing and/or halting mucociliary clearance.

Detection and measurement of electroreflectance on quantum cascade laser device using Fourier transform infrared microscope

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

Enobio, Eli Christopher I.; Ohtani, Keita; Ohno, Yuzo

2013-12-02

We demonstrate the use of a Fourier Transform Infrared microscope system to detect and measure electroreflectance (ER) from mid-infrared quantum cascade laser (QCL) device. To characterize intersubband transition (ISBT) energies in a functioning QCL device, a microscope is used to focus the probe on the QCL cleaved mirror. The measured ER spectra exhibit resonance features associated to ISBTs under applied electric field in agreement with the numerical calculations and comparable to observed photocurrent, and emission peaks. The method demonstrates the potential as a characterization tool for QCL devices.

Synthesis of the Novel Type of Bimodal Ceramic Nanowires from Polymer and Composite Fibrous Mats

PubMed Central

Matysiak, Wiktor

2018-01-01

The purpose of this paper was to produce SiO2 and TiO2 nanowires via the electrospinning process from a polyvinylpyrrolidone (PVP)/Tetraethyl orthosilicate (TEOS)/Titanium (IV) butoxide (TNBT)/dimethylformamide (DMF) and ethanol (EtOH) solution. The as-obtained nanofibers were calcined at temperatures ranging from 400 °C to 600 °C in order to remove the organic phase. The one-dimensional ceramic nanostructures were studied using a scanning electron microscope (SEM) and a transmission electron microscope (TEM) to analyze the influence of the used temperature on the morphology and structures of the obtained ceramic nanomaterials. In order to examine the chemical structure of the nanowires, energy dispersive spectrometry (EDX) and Fourier-Transform Infrared spectroscopy (FTIR) were used. The optical property analysis was performed on the basis of UV-Vis spectra of absorbance as a function of the wavelength. Using the modified Swanepoel method, which the authors proposed and the recorded absorbance spectra allowed to determine the banded refractive index n, real n′ and imaginary k part of the refractive index as a function of the wavelength, complex dielectric permeability ε, and real and imaginary part εr and εi of the dielectric permeability as a function of the radiation energy of the produced ceramic nanowires. PMID:29558456

Driving the photoluminescent and structural properties of X2-Y2SiO5 by varying the dopant Dy3+ concentration towards cool WLED applications

NASA Astrophysics Data System (ADS)

Ramakrishna, G.; Nagabhushana, H.; Hareesh, K.; Sunitha, D. V.

2017-07-01

Dy3+ doped Y2SiO5 nanophosphors were synthesized by solution combustion technique using Calotropis gigantean milk latex and NaCl as fuel and flux respectively. Powder X-ray diffraction (PXRD) confirmed the formation of monoclinic X2-phase Y2SiO5 belonging to the phase group C2/c. Fourier transform infrared spectroscopy (FTIR) shows characteristic metal-oxygen (Y-O) vibration band at 721 cm-1. Transmission electron microscopic (TEM) and Scanning electron microscopic (SEM) morphological feature exhibits non-uniform almost spherical shaped nanosized particles. The photoluminescence (PL) emission peaks, recorded at 388 nm, showed radiative emissions at 483, 575 and 636 nm respectively. Judd-Ofelt (JO) analysis was carried out to estimate the radiative (AR) properties, radiative life time (τR), branching ratio (βR) and stimulated emission crossection (σλp). The CIE and CCT was estimated using McCamy empirical formula. In the beginning, the CIE co-ordinate values were lying in the light blue region. However, with increase in Dy3+ concentration the values shifted towards white region. CCT value was found to be ∼6984 K. Therefore, Y2SiO5:Dy3+ (9 mol%) can be used for cool day light and WLED applications.

Synthesis of hydroxyapatite nanoparticles by a novel ultrasonic assisted with mixed hollow sphere template method.

PubMed

Gopi, D; Indira, J; Kavitha, L; Sekar, M; Mudali, U Kamachi

2012-07-01

Hydroxyapatite (HAP) is the main inorganic component of bone material and is widely used in various biomedical applications due to its excellent bioactivity and biocompatibility. In this paper, we have reported the synthesis of hydroxyapatite nanoparticles by a novel ultrasonic assisted mixed template directed method. In this method glycine-acrylic acid (GLY-AA) hollow spheres were used as an organic template which could be prepared by mixing of glycine with acrylic acid. The as-synthesized HAP nanoparticles were characterized by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), scanning electron microscope (SEM) and tunnelling electron microscope (TEM) to investigate the nature of bonding, crystallinity, size and shape. The thermal stability of as-synthesized nanoparticles was also investigated by the thermo gravimetric analysis (TGA). The effect of ultrasonic irradiation time on the crystallinity and size of the HAP nanoparticles in presence of glycine-acrylic acid hollow spheres template were investigated. From the inspection of the above results it is confirmed that the crystallinity and size of the HAP nanoparticles decrease with increasing ultrasonic irradiation time. Hence the proposed synthesis strategy provides a facile pathway to obtain nano sized HAP with high quality, suitable size and morphology. Copyright © 2012 Elsevier B.V. All rights reserved.

Fabrication of nano-silver particles using Cymodocea serrulata and its cytotoxicity effect against human lung cancer A549 cells line

NASA Astrophysics Data System (ADS)

Palaniappan, P.; Sathishkumar, G.; Sankar, R.

2015-03-01

The present study reports, green synthesis of bioactive silver nanoparticles (AgNPs) under different temperature (60 °C, room temperature and 4° refrigerator) using the aqueous extract of sea grass Cymodocea serrulata as a potential bioreductant. Increased temperature fabricates more AgNPs compare to room temperature and refrigerator condition. At first the reduction of Ag+ ions were confirmed through color change which produces an absorbance spectra at 420 nm in UV-Visible spectrophotometer. Additionally various exclusive instrumentations such as X-ray diffraction (XRD), Dynamic light scattering (DLS), scanning electron microscope (SEM) analysis and Transmission electron microscope (TEM) were authorizes the biosynthesis and physio-chemical characterization of AgNPs. From Fourier transform infrared spectroscopy (FTIR) analysis, it was identified that the water soluble fractions of the sea grass mainly responsible for reduction of ionic silver (Ag+) into (Ag0) nano-ranged particles and also they act as stabilizing agent to sustain the durability of NPs for long period of time. Further, synthesized AgNPs shows potential cytotoxicity against human lung cancer A549 cells (LD50-100 μg/ml). The overall results suggest that C. serrulata is a valuable bioresource to generate rapid and eco-friendly bioactive AgNPs towards cancer therapy.

Preparation and effect of thermal treatment on Gd2O3:SiO2 nanocomposite

NASA Astrophysics Data System (ADS)

Ahlawat, Rachna

2015-04-01

Rare earth oxides have been extensively investigated due to their fascinating properties such as enhanced luminescence efficiency, lower lasing threshold, high-performance luminescent devices, drug-carrying vehicle, contrast agent in magnetic resonance imaging (MRI), up-conversion materials, catalysts and time-resolved fluorescence (TRF) labels for biological detection etc. Nanocomposites of silica gadolinium oxide have been successfully synthesized by sol-gel process using hydrochloric acid as a catalyst. Gd(NO3)3ṡ6H2O and tetraethyl orthosilicate (TEOS) were used as precursors to obtain powdered form of gadolinum oxide:silica (Gd2O3:SiO2) composite. The powdered samples having 2.8 mol% Gd2O3 were annealed at 500°C and 900°C temperature for 6 h and characterized by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), scanning electron microscope (SEM) and transmission electron microscope (TEM). The effect of annealing on the phase evolution of the composite system has been discussed in detail. It was found that the sintering of gadolinium precursor plays a pivotal role to obtain crystalline phase of Gd2O3. Cubic phase of gadolinium oxide was developed for annealed sample at 900°C (6 h) with an average grain size 12 nm.

Three dimensional profile measurement using multi-channel detector MVM-SEM

NASA Astrophysics Data System (ADS)

Yoshikawa, Makoto; Harada, Sumito; Ito, Keisuke; Murakawa, Tsutomu; Shida, Soichi; Matsumoto, Jun; Nakamura, Takayuki

2014-07-01

In next generation lithography (NGL) for the 1x nm node and beyond, the three dimensional (3D) shape measurements such as side wall angle (SWA) and height of feature on photomask become more critical for the process control. Until today, AFM (Atomic Force Microscope), X-SEM (cross-section Scanning Electron Microscope) and TEM (Transmission Electron Microscope) tools are normally used for 3D measurements, however, these techniques require time-consuming preparation and observation. And both X-SEM and TEM are destructive measurement techniques. This paper presents a technology for quick and non-destructive 3D shape analysis using multi-channel detector MVM-SEM (Multi Vision Metrology SEM), and also reports its accuracy and precision.

Preparation and physicochemical characterization of cellulose nanocrystals from industrial waste cotton

NASA Astrophysics Data System (ADS)

Thambiraj, S.; Ravi Shankaran, D.

2017-08-01

We aimed to develop a simple and low-cost method for the production of high-performance cellulose nanomaterials from renewable and sustainable resources. Here, cellulose microcrystals (CMCs) were prepared by controlled acidic and basic hydrolysis of cotton from textile industry wastes. The resulted CMCs were further converted into cellulose nanocrystals (CNCs) with high crystallinity by acidic hydrolysis. The physicochemical characteristics and morphological feature of CMCs and CNCs were studied by various analytical techniques such as UV-vis spectroscopy, Fourier-transform infrared spectroscopy (FT-IR), Scanning electron microscope (SEM), Fluorescence spectroscopy, Atomic force microscopy (AFM), High-resolution transmission electron microscopy (HR-TEM), X-ray photoelectron spectroscopy (XPS) and X-ray diffraction (XRD). The isolated CNCs possess a needle-like morphological structure with the longitudinal and lateral dimensions of 180 ± 60 nm, 10 ± 1 nm, respectively. The AFM result reveals that the CNCs have a high aspect ratio of 40 ± 14 nm and the average thickness of 6.5 nm. The XRD and TEM analysis indicate that the synthesized CNCs possess face-centered cubic crystal structure. Preliminary experiments were carried out to fabricate CNCs incorporated poly (vinyl alcohol) (PVA) film. The results suggest that the concept of waste to wealth could be well executed from the prepared CNCs, which have great potential for various applications including bio-sensors, food packaging and drug delivery applications.

Amphiphilic chitosan derivatives as carrier agents for rotenone

NASA Astrophysics Data System (ADS)

Kamari, Azlan; Aljafree, Nurul Farhana Ahmad

2017-08-01

In the present study, the feasibility of amphiphilic chitosan derivatives, namely oleoyl carboxymethyl chitosan (OCMCs), N,N-dimethylhexadecyl carboxymethyl chitosan (DCMCs) and deoxycholic acid carboxymethyl chitosan (DACMCs) as carrier agents for rotenone in water-insoluble pesticide formulations was investigated. Fourier Transform Infrared (FTIR) Spectrometer, CHN-O Elemental Analyser (CHN-O) and Transmission Electron Microscope (TEM) were used to characterise amphiphilic chitosan derivatives. The critical micelle concentration (CMC) of amphiphilic chitosan derivatives was determined using a Fluorescence Spectrometer. A High Performance Liquid Chromatography (HPLC) was used to determine the ability of OCMCs, DCMCs and DACMCs to load and release rotenone in an in vitro system. Based on TEM analysis, results have shown that amphiphilic chitosan derivatives formed self-assembly and exhibited spherical shape. The CMC values determined for OCMCs, DCMCs and DACMCs were 0.093, 0.098 and 0.468 mg/mL, respectively. The encapsulation efficiency (EE) values for the materials were more than 97.0%, meanwhile the loading capacity (LC) values were greater than 0.90%. OCMCs, DCMCs and DACMCs micelles exhibited an excellent ability to control the release of rotenone, of which 90.0% of rotenone was released within 40 to 52 h. In conclusion, OCMCs, DCMCs and DACMCs possess several key features to act as effective carrier agents for rotenone. Overall, amphiphilic chitosan derivatives produced in this study were successfully increased the solubility of rotenone by 49.0 times higher than free rotenone.

Green synthesis of gold nanoparticles using Citrus maxima peel extract and their catalytic/antibacterial activities.

PubMed

Yuan, Chun-Gang; Huo, Can; Gui, Bing; Cao, Wei-Ping

2017-08-01

The peel of Citrus maxima ( C. maxima ) is the primary byproducts during the process of fruit or juice in food industries, and it was always considered as biomass waste for further treatments. In this study, the authors reported a simple and eco-friendly method to synthesise gold nanoparticles (AuNPs) using C. maxima peel extract as reducing and capping agents. The synthesised AuNPs were characterised by UV-visible spectrum, X-ray diffraction (XRD), transmission electron microscope (TEM) and Fourier-transform infrared spectroscopy (FTIR). The UV-visible spectrum of the AuNPs colloid showed a characteristic peak at 540 nm. The peaks of XRD analysis at (2 θ ) 38.30°, 44.28°, 64.62°, 77.57° and 81.75° were assigned to (111), (200), (220), (311) and (222) planes of the face-centered cubic (fcc) lattice of gold. The TEM images showed that AuNPs were nearly spherical in shape with the size of 8-25 nm. The FTIR spectrum revealed that some bioactive compounds capped the surface of synthesised AuNPs. The biosynthesised AuNPs performed strong catalytic activity in degradation of 4-nitrophenol to 4-aminophenol and good antibacterial activity against both gram negative ( Escherichia coli ) and gram positive ( Staphylococcus aureus ) bacterium. The synthesis procedure was proved simple, cost effective and environment friendly.

Methotrexate-conjugated magnetic nanoparticles for thermochemotherapy and magnetic resonance imaging of tumor

NASA Astrophysics Data System (ADS)

Gao, Fuping; Yan, Zixing; Zhou, Jing; Cai, Yuanyuan; Tang, Jintian

2012-10-01

There is significant interest in recent years in developing magnetic nanoparticles (MNPs) having multifunctional characteristics with complimentary roles. In this study, methotrexate (MTX) was conjugated on the iron oxide magnetic nanoparticles surface via a poly(ethyleneimine) self-assembled monolayer (MTX-MNPs). The novel platform combined cancer chemotherapy, hyperthermia and potential monitoring of the progression of disease through magnetic resonance imaging (MRI). The conjugation of MTX on the magnetite surface was confirmed by Fourier transform infrared spectroscopy and change of zeta potential. Transmission electron microscope (TEM) showed that MTX-MNPs were morphologically spherical. The average diameter of MTX-MNPs was 30.1 ± 5.2 nm determined by dynamic light scattering. Magnetic measurements revealed that the saturation magnetization of MTX-MNPs reached 68.8 emu/g and the nanoparticles were superparamagnetic. The MTX-MNPs had good heating properties in an alternating magnetic field. TEM results showed that a larger number of MTX-MNPs were internalized into the MCF-7 cellular cytoplasm compared with the MNPs. The MTX-MNPs demonstrated highly synergistic antiproliferative effects of simultaneous chemotherapy and hyperthermia in MCF-7 breast cancer cells. A significant negative contrast enhancement was observed with magnetic resonance phantom imaging for MCF-7 cells over L929cells, when both were cultured with the nanoconjugate. The MTX-MNPs with combined characteristics of thermochemotherapy and MRI could be of high clinical significance in the treatment of tumor.

Comparative analysis of imaging configurations and objectives for Fourier microscopy.

PubMed

Kurvits, Jonathan A; Jiang, Mingming; Zia, Rashid

2015-11-01

Fourier microscopy is becoming an increasingly important tool for the analysis of optical nanostructures and quantum emitters. However, achieving quantitative Fourier space measurements requires a thorough understanding of the impact of aberrations introduced by optical microscopes that have been optimized for conventional real-space imaging. Here we present a detailed framework for analyzing the performance of microscope objectives for several common Fourier imaging configurations. To this end, we model objectives from Nikon, Olympus, and Zeiss using parameters that were inferred from patent literature and confirmed, where possible, by physical disassembly. We then examine the aberrations most relevant to Fourier microscopy, including the alignment tolerances of apodization factors for different objective classes, the effect of magnification on the modulation transfer function, and vignetting-induced reductions of the effective numerical aperture for wide-field measurements. Based on this analysis, we identify an optimal objective class and imaging configuration for Fourier microscopy. In addition, the Zemax files for the objectives and setups used in this analysis have been made publicly available as a resource for future studies.

Fabrication of a temperature-responsive and recyclable MoS2 nanocatalyst through composting with poly (N-isopropylacrylamide)

NASA Astrophysics Data System (ADS)

Liu, Yan; Chen, Pengpeng; Nie, Wangyan; Zhou, Yifeng

2018-04-01

A temperature-responsive, recyclable nanocatalyst was fabricated by composting the exfoliated molybdenum disulfide (MoS2) nanosheets with poly (N-isopropylacry lamide) (PNIPAM). The structure and morphology of MoS2/PNIPAM nanocatalyst was fully characterized by Fourier transform infrared spectroscopy (FT-IR), X-ray photoelectron spectroscopy (XPS), Thermogravimetry analysis (TGA), Scanning electron microscope (SEM) and Transmission electron microscopy (TEM). The temperature-responsive properties of the MoS2/PNIPAM nanocatalyst were confirmed by Dynamic Light Scattering (DLS) and Ultraviolet-visible ((UV-vis)) absorption spectroscopy. The catalytic activities of the MoS2/PNIPAM nanocatalyst were studied using the reduction reaction of 4-nitrophenol (4-NP) to 4-aminophenol (4-AP) as the model reaction. Results showed that the catalytic activity of the MoS2/PNIPAM nanocatalyst could be regulated by temperature. Furthermore, when the temperature went higher than the low critical solution temperature (LCST) of PNIPAM, the MoS2/PNIPAM nanocatalyst tended to aggregated to form bulk materials from homogeneous suspension.

Radioactive Cobalt(II) Removal from Aqueous Solutions Using a Reusable Nanocomposite: Kinetic, Isotherms, and Mechanistic Study

PubMed Central

Wang, Ximing; Chen, Zhangjing

2017-01-01

A lignocellulose/montmorillonite (LMT) nanocomposite was prepared as a reusable adsorbent for cobalt(II) ions, and characterized by nitrogen (N2) adsorption/desorption isotherm, X-ray Diffraction (XRD), Scanning Electron Microscope (SEM), Transmission Electron Microscopy (TEM), and Fourier Transform Infrared Spectroscopy (FTIR). LMT exhibited efficient adsorption of cobalt ions (Co(II)), and the adsorbed Co(II) was readily desorbed by nitric acid (HNO3). All parameters affecting the adsorption and/or desorption of Co(II), including initial Co(II) concentration, pH value, temperature, HNO3 concentration, and time, were optimized. The kinetic data analysis showed that the adsorption followed the pseudo-second-order kinetic model and fit well into the Langmuir isotherm equation. Notably, the nanocomposite can be used four times without significantly losing adsorbent capability. The Energy-Dispersive X-ray (EDX) and FTIR spectra analysis also revealed that the adsorption mechanism may be mainly a chemical adsorption dominated process. PMID:29186794

An electrochemical sensor based on nitrogen doped carbon material prepared from nitrogen-containing precursors

NASA Astrophysics Data System (ADS)

Cui, G. Y.; Wang, C. Y.; Xiang, G. Q.; Zhou, B.

2018-01-01

In this work, a nitrogen doped carbon material (NDC) was prepared by using a copper adenine complex as precursor and applied to electrochemical sensing of Vitamin B2 (VB2). The experimental results show that the nitrogen doped carbon material is obtained after calcination at 650 °C under argon atmosphere, afterwards, which were characterized by X-ray diffraction (XRD), transmission electron microscope (TEM), fourier transform infrared (FT-IR), and electrochemical method. According to the XRD data, the product was a carbon material, and infrared data demonstrates that there are two kinds of carbonyl nitrogen combination, respectively, C-N and C = N combination of ways. Importantly, we used NDC to construct electrochemical biosensor to detect VB2 by differential pulse voltammetry (DPV). The linear range was 6 × 10-6 - 3.5 × 10-4 M (R=0.9962), the minimum detection limit was 5.4 × 10-6 M, and the sensitivity is better. Consequently, it has better sensing performance.

Synthesis, characterization and microwave characteristics of ATP/BaFe12O19/PANI ternary composites

NASA Astrophysics Data System (ADS)

Bai, Dezhong; Feng, Huixia; Chen, Nali; Tan, Lin; Qiu, Jianhui

2018-07-01

In this paper, we introduced attapulgite (ATP) into the system of ferrite composites for the first time. By sol-gel self-propagating combustion method, attapulgite/barium ferrite (ATP/BaFe12O19) was prepared, and then ternary composites of attapulgite/barium ferrite/polyaniline (ATP/BaFe12O19/PANI) were obtained by in-situ oxidative polymerization of aniline on ATP/BaFe12O19 mixture. The phase composition, morphology and electromagnetic properties of the as-prepared composites were characterized by X-ray diffraction (XRD), Transmission election microscope (TEM), Fourier transform infrared (FTIR), vibrating sample magnetometer (VSM) and vector network analyzer (VNA). We found that the ATP/BaFe12O19/PANI composites at a thickness of 2 mm have the minimum reflection loss of -11.89 dB at 11.28 GHz, besides the effective absorption bandwidth (less than -5 dB) reached 6.39 GHz (from 8.42 GHz to 14.81 GHz).

Spectroscopic properties in Er3+-doped germanotellurite glasses and glass ceramics for mid-infrared laser materials.

PubMed

Kang, Shiliang; Xiao, Xiudi; Pan, Qiwen; Chen, Dongdan; Qiu, Jianrong; Dong, Guoping

2017-03-07

Transparent Er 3+ -doped germanotellurite glass ceramics (GCs) with variable Te/Ge ratio were prepared by controllable heat-treated process. X-ray diffraction (XRD) and transmission electron microscope (TEM) confirmed the formation of nanocrystals in glass matrix. Raman spectra were used to investigate the evolution of glass structure and photon energy. Fourier transform infrared (FTIR) spectra were introduced to characterize the change of hydroxyl group (OH - ) content. Enhanced 2.7 μm emission was achieved from Er 3+ -doped GCs upon excitation with a 980 nm laser diode (LD), and the influence of GeO 2 concentration and heat-treated temperature on the spectroscopic properties were also discussed in detail. It is found that the present Er 3+ -doped GC possesses large stimulated emission cross section at around 2.7 μm (0.85 × 10 -20  cm 2 ). The advantageous spectroscopic characteristics suggest that the obtained GC may be a promising material for mid-infrared fiber lasers.

Preparation of silver nano-particles immobilized onto chitin nano-crystals and their application to cellulose paper for imparting antimicrobial activity.

PubMed

Li, Zhihan; Zhang, Ming; Cheng, Dong; Yang, Rendang

2016-10-20

Immobilized silver nano-particles (Ag NPs) possess excellent antimicrobial properties due to their unique surface characteristics. In this paper, immobilized silver nano-particles were synthesized in the presence of chitin nano-crystals (CNC) based on the Tollens mechanism (reduction of silver ion by aldehydes in the chitosan oligosaccharides (COS)) under microwave-assisted conditions. The prepared Ag NPs-loaded CNC nano-composites were then applied onto the paper surface via coating for the preparation of antibacterial paper. Fourier transform infrared (FT-IR) and X-ray diffraction (XRD) results confirmed that the Ag NPs were immobilized onto the CNC. The transmission electron microscope (TEM) and scanning electron microscopy (SEM) results further revealed that the spherical Ag NPs (5-12nm) were well dispersed on the surface of CNC. The coated paper made from the Ag NPs-loaded CNC nano-composites exhibited a high effectiveness of the antibacterial activity against E. coli or S. aureus. Copyright © 2016 Elsevier Ltd. All rights reserved.

A novel flexible room temperature ethanol gas sensor based on SnO2 doped poly-diallyldimethylammonium chloride.

PubMed

Zhan, Shuang; Li, Dongmei; Liang, Shengfa; Chen, Xin; Li, Xia

2013-04-02

A novel flexible room temperature ethanol gas sensor was fabricated and demonstrated in this paper. The polyimide (PI) substrate-based sensor was formed by depositing a mixture of SnO2 nanopowder and poly-diallyldimethylammonium chloride (PDDAC) on as-patterned interdigitated electrodes. PDDAC acted both as the binder, promoting the adhesion between SnO2 and the flexible PI substrate, and the dopant. We found that the response of SnO2-PDDAC sensor is significantly higher than that of SnO2 alone, indicating that the doping with PDDAC effectively improved the sensor performance. The SnO2-PDDAC sensor has a detection limit of 10 ppm at room temperature and shows good selectivity to ethanol, making it very suitable for monitoring drunken driving. The microstructures of the samples were examined by scanning electron microscopy (SEM), X-ray diffraction (XRD), transmission electron microscope (TEM) and Fourier transform infrared spectra (FT-IR), and the sensing mechanism is also discussed in detail.

Spectroscopic properties in Er3+-doped germanotellurite glasses and glass ceramics for mid-infrared laser materials

PubMed Central

Kang, Shiliang; Xiao, Xiudi; Pan, Qiwen; Chen, Dongdan; Qiu, Jianrong; Dong, Guoping

2017-01-01

Transparent Er3+-doped germanotellurite glass ceramics (GCs) with variable Te/Ge ratio were prepared by controllable heat-treated process. X-ray diffraction (XRD) and transmission electron microscope (TEM) confirmed the formation of nanocrystals in glass matrix. Raman spectra were used to investigate the evolution of glass structure and photon energy. Fourier transform infrared (FTIR) spectra were introduced to characterize the change of hydroxyl group (OH−) content. Enhanced 2.7 μm emission was achieved from Er3+-doped GCs upon excitation with a 980 nm laser diode (LD), and the influence of GeO2 concentration and heat-treated temperature on the spectroscopic properties were also discussed in detail. It is found that the present Er3+-doped GC possesses large stimulated emission cross section at around 2.7 μm (0.85 × 10−20 cm2). The advantageous spectroscopic characteristics suggest that the obtained GC may be a promising material for mid-infrared fiber lasers. PMID:28266570

Preparation of nanostructured and nanosheets of MoS2 oxide using oxidation method.

PubMed

Amini, Majed; Ramazani S A, Ahmad; Faghihi, Morteza; Fattahpour, Seyyedfaridoddin

2017-11-01

Molybdenum disulfide (MoS 2 ), a two-dimensional transition metal has a 2D layered structure and has recently attracted attention due to its novel catalytic properties. In this study, MoS 2 has been successfully intercalated using chemical and physical intercalation techniques, while enhancing its surface properties. The final intercalated MoS 2 is of many interests because of its low-dimensional and potential properties in in-situ catalysis. In this research, we report different methods to intercalate the layers of MoS 2 successfully using acid-treatment, ultrasonication, oxidation and thermal shocking. The other goal of this study is to form SO bonds mainly because of expected enhanced in-situ catalytic operations. The intercalated MoS 2 is further characterized using analyses such as Fourier Transform Infrared Spectroscopy (FTIR), Raman, Contact Angle, X-ray diffraction (XRD), Field Emission Scanning Electron Microscope (FESEM), Energy Dispersive X-Ray Microanalysis (EDAX), Transmission electron microscopy (TEM), and BET. Copyright © 2017. Published by Elsevier B.V.

Fabrication and characterization of morphology-tuned single-crystal monodisperse Fe3O4 nanocrystals

NASA Astrophysics Data System (ADS)

Yu, Xuegang; Shan, Yan; Chen, Kezheng

2018-05-01

Monodisperse Fe3O4 nanocrystals with different size and morphology have been successfully fabricated by a facile high temperature reflow method. The presented materials were characterized by X-ray diffraction (XRD), fourier transform infrared (FTIR) spectroscopy, transmission electron microscope (TEM), selection area electron diffraction (SAED) and magnetic property measurement system (MPMS). The results showed that the as-prepared materials have face-centered cubic structures. Oleic acid plays a key role in the dispersion of Fe3O4 nanocrystals. The cubic and octahedral nanocrystals are enclosed by {1 0 0} and {1 1 1} lattice planes. The MPMS measurements show that magnetic properties are closely related to the sizes of the materials, and there is a stronger dipolar interaction between Fe3O4 nanocrystals with larger sizes. The controllable magnetic property and good dispersion endow the as-synthesized materials with great potential applications in magnetic fluid fields including sealing, medical equipment, mineral processing and other aspects.

The preparation and performance of calcium carbide-derived carbon/polyaniline composite electrode material for supercapacitors

NASA Astrophysics Data System (ADS)

Zheng, Liping; Wang, Ying; Wang, Xianyou; Li, Na; An, Hongfang; Chen, Huajie; Guo, Jia

Calcium carbide (CaC 2)-derived carbon (CCDC)/polyaniline (PANI) composite materials are prepared by in situ chemical oxidation polymerization of an aniline solution containing well-dispersed CCDC. The structure and morphology of CCDC/PANI composite are characterized by Fourier infrared spectroscopy (FTIR), scanning electron microscope (SEM), transmission electron microscopy (TEM) and N 2 sorption isotherms. It has been found that PANI was uniformly deposited on the surface and the inner pores of CCDC. The supercapacitive behaviors of the CCDC/PANI composite materials are investigated with cyclic voltammetry (CV), galvanostatic charge/discharge and cycle life measurements. The results show that the CCDC/PANI composite electrodes have higher specific capacitances than the as grown CCDC electrodes and higher stability than the conducting polymers. The capacitance of CCDC/PANI composite electrode is as high as 713.4 F g -1 measured by cyclic voltammetry at 1 mV s -1. Besides, the capacitance retention of coin supercapacitor remained 80.1% after 1000 cycles.

Preparation of high-quality planar FeRh thin films for in situ TEM investigations

NASA Astrophysics Data System (ADS)

Almeida, Trevor P.; McGrouther, Damien; Pivak, Yevheniy; Perez Garza, Hector Hugo; Temple, Rowan; Massey, Jamie; Marrows, Christopher H.; McVitie, Stephen

2017-10-01

The preparation of a planar FeRh thin film using a focused ion beam (FIB) secondary electron microscope (SEM) for the purpose of in situ transmission electron microscopy (TEM) is presented. A custom SEM stub with 45° faces allows for the transfer and milling of the sample on a TEM heating chip, whilst Fresnel imaging within the TEM revealed the presence of the magnetic domain walls, confirming the quality of the FIB-prepared sample.

Microstructural studies of 35 degrees C copper Ni-Ti orthodontic wire and TEM confirmation of low-temperature martensite transformation.

PubMed

Brantley, William A; Guo, Wenhua; Clark, William A T; Iijima, Masahiro

2008-02-01

Previous temperature-modulated differential scanning calorimetry (TMDSC) study of nickel-titanium orthodontic wires revealed a large exothermic low-temperature peak that was attributed to transformation within martensitic NiTi. The purpose of this study was to use transmission electron microscopy (TEM) to verify this phase transformation in a clinically popular nickel-titanium wire, identify its mechanism and confirm other phase transformations found by TMDSC, and to provide detailed information about the microstructure of this wire. The 35 degrees C Copper nickel-titanium wire (Ormco) with cross-section dimensions of 0.016 in. x 0.022 in. used in the earlier TMDSC investigation was selected. Foils were prepared for TEM analyses by mechanical grinding, polishing, dimpling, ion milling and plasma cleaning. Standard bright-field and dark-field TEM images were obtained, along with convergent-beam electron diffraction patterns. A cryo-stage with the electron microscope (Phillips CM 200) permitted the specimen to be observed at -187, -45, and 50 degrees C, as well as at room temperature. Microstructures were also observed with an optical microscope and a scanning electron microscope. Room temperature microstructures had randomly oriented, elongated grains that were twinned. Electron diffraction patterns confirmed that phase transformations took place over temperature ranges previously found by TMDSC. TEM observations revealed a high dislocation density and fine-scale oxide particles, and that twinning is the mechanism for the low-temperature transformation in martensitic NiTi. TEM confirmed the low-temperature peak and other phase transformations observed by TMDSC, and revealed that twinning in martensite is the mechanism for the low-temperature peak. The high dislocation density and fine-scale oxide particles in the microstructure are the result of the wire manufacturing process.

Biologically synthesized titanium oxide nanostructures combined with morphogenetic protein as wound healing agent in the femoral fracture after surgery.

PubMed

Zhang, Yushu; Zhang, Chuanlian; Liu, Kemiao; Zhu, Xia; Liu, Fang; Ge, Xiaofen

2018-05-01

The aim of the present study is to develop novel approach for the green synthesis of titanium oxide nanoparticles (TiO 2 NPs) using Eichhornia crassipes extract and calcined at different temperatures for evaluate the wound healing activity in the femoral fracture. The synthesized TiO 2 are formed different (plate and rod-like) nanostructures at various calcination temperatures. These samples were characterized by X-ray diffraction (XRD), Fourier transform-infrared spectroscopy (FTIR), Field emission scanning electron microscope (FE-SEM) and transmission electron microscope (TEM). Microscopic studies of TiO 2 NPs revealed that the synthesized TiO 2 NPs are formed well-defined rod-like structures at 400 °C with size ranged from 200 nm to 500 nm. The characterized plate and rod-like TiO 2 NPs are combined with human morphogenetic protein (HbMP) to improving its wound healing activity and osteoblast properties on femoral fractures. The biocompatibility was tested by using human bone marrow mesenchymal stem cells (BMSC) cells and antibacterial efficacy analyzed using human pathogenica bacteria Staphylococcus aureus and Escherichia coli through agar well diffusion assay. The green synthesized rod-like TiO 2 NPs combined with HbMP has been exhibited effective bone fusion behaviors with biomechanical properties and also improved antibacterial activity against pathogenic bacteria. From this study results, it is suggested that green synthesized TiO 2 NPs could be used effectively in biomedical application. Copyright © 2018. Published by Elsevier B.V.

Electron Microscopist | Center for Cancer Research

Cancer.gov

PROGRAM DESCRIPTION The Cancer Research Technology Program (CRTP) develops and implements emerging technology, cancer biology expertise and research capabilities to accomplish NCI research objectives. The CRTP is an outward-facing, multi-disciplinary hub purposed to enable the external cancer research community and provides dedicated support to NCI’s intramural Center for Cancer Research (CCR). The dedicated units provide electron microscopy, protein characterization, protein expression, optical microscopy and genetics. These research efforts are an integral part of CCR at the Frederick National Laboratory for Cancer Research (FNLCR). CRTP scientists also work collaboratively with intramural NCI investigators to provide research technologies and expertise. KEY ROLES/RESPONSIBILITIES - THIS POSITION IS CONTINGENT UPON FUNDING APPROVAL The Electron Microscopist will: Operate ultramicrotomes (Leica) and other instrumentation related to the preparation of embedded samples for EM (TEM and SEM) Operate TEM microscopes, (specifically Hitachi, FEI T20 and FEI T12) as well as SEM microscopes (Hitachi); task will include loading samples, screening, and performing data collection for a variety of samples: from cells to proteins Manage maintenance for the TEM and SEM microscopes Provide technical advice to investigators on sample preparation and data collection

Multiple double cross-section transmission electron microscope sample preparation of specific sub-10 nm diameter Si nanowire devices.

PubMed

Gignac, Lynne M; Mittal, Surbhi; Bangsaruntip, Sarunya; Cohen, Guy M; Sleight, Jeffrey W

2011-12-01

The ability to prepare multiple cross-section transmission electron microscope (XTEM) samples from one XTEM sample of specific sub-10 nm features was demonstrated. Sub-10 nm diameter Si nanowire (NW) devices were initially cross-sectioned using a dual-beam focused ion beam system in a direction running parallel to the device channel. From this XTEM sample, both low- and high-resolution transmission electron microscope (TEM) images were obtained from six separate, specific site Si NW devices. The XTEM sample was then re-sectioned in four separate locations in a direction perpendicular to the device channel: 90° from the original XTEM sample direction. Three of the four XTEM samples were successfully sectioned in the gate region of the device. From these three samples, low- and high-resolution TEM images of the Si NW were taken and measurements of the NW diameters were obtained. This technique demonstrated the ability to obtain high-resolution TEM images in directions 90° from one another of multiple, specific sub-10 nm features that were spaced 1.1 μm apart.

Investigation of C3 S hydration mechanism by transmission electron microscope (TEM) with integrated Super-XTM EDS system.

PubMed

Sakalli, Y; Trettin, R

2017-07-01

Tricalciumsilicate (C 3 S, Alite) is the major component of the Portland cement clinker. Hydration of Alite is decisive in influencing the properties of the resulting material. This is due to its high content in cement. The mechanism of the hydration of C 3 S is very complicated and not yet fully understood. There are different models describing the hydration of C 3 S in various ways. In this work for a better understanding of hydration mechanism, the hydrated C 3 S was investigated by using the transmission electron microscope (TEM) and for the first time, the samples for the investigations were prepared by using of focused ion beam from sintered pellets of C 3 S. Also, an FEI Talos F200x with an integrated Super-X EDS system was used for the investigations. FEI Talos F200X combines outstanding high-resolution S/TEM and TEM imaging with energy dispersive X-ray spectroscopy signal detection, and 3D chemical characterization with compositional mapping. TEM is a very powerful tool for material science. A high energy beam of electrons passes through a very thin sample, and the interactions between the electrons and the atoms can be used to observe the structure of the material and other features in the structure. TEM can be used to study the growth of layers and their composition. TEM produces high-resolution, two-dimensional images and will be used for a wide range of educational, science and industry applications. Chemical analysis can also be performed. The purpose of these investigations was to get the information about the composition of the C-S-H phases and some details of the nanostructure of the C-S-H phases. © 2017 The Authors Journal of Microscopy © 2017 Royal Microscopical Society.

Structural and spectral properties of undoped and tungsten doped Zn3(PO4)2ZnO nanopowders

NASA Astrophysics Data System (ADS)

Satyavathi, K.; Subba Rao, M.; Nagabhaskararao, Y.; Cole, Sandhya

2018-01-01

Pure and tungsten doped Zn3(PO4)2ZnO nanopowders (NPs) are prepared using sol-gel method. It has the longest track record of used in dentistry. It is used for cementation of inlays, crowns and orthodontic appliances. The systematic investigations like X-ray Diffraction (XRD), Scanning electron microscope (SEM) with energy dispersive X-ray (EDX) spectroscope, Transmission electron microscope (TEM), Fourier transform infrared (FT-IR) spectroscopy, Optical absorption, Photoluminescence (PL) and Electron Paramagnetic Resonance (EPR) spectroscopic techniques are carried out for the prepared NPs. XRD pattern reveals that the prepared samples are in crystalline nature in which Zn3(PO4)2 corresponding to monoclinic phase and ZnO corresponding to hexagonal wurtzite phase, the average crystallite size of prepared nanopowders is in the range of 20-30 nm. The lattice strain, lattice cell parameters, unit cell volume and dislocation density of the prepared NPs are also calculated. The morphology of the prepared NPs is analyzed with SEM and TEM images. The distribution of Zn, P, O and W species in the prepared samples are identified by the chemical composition mapping through EDX. IR spectra of prepared samples exhibit the characteristic sharp absorption band peaks. The sharp absorption bands observed in the region 1200-900 cm-1 are due to complex stretching of characteristic PO43- groups. The absorption spectra exhibit a broad band around 696 nm is recognized due to 2B2g → 2B1g (dxy → dx2- y2) transition of tungsten ions. The PL spectra exhibit four emission peaks in the visible region indicating the quantum-confinement-induced photoluminescence. The CIE chromaticity diagram suggests that the prepared NPs have good color purity. The EPR spectra indicate that the W5+ ions occupy octahedral site symmetry in the host lattice.

Effect of different physicochemical conditions on the synthesis of silver nanoparticles using fungal cell filtrate of Aspergillus oryzae (MTCC No. 1846) and their antibacterial effect

NASA Astrophysics Data System (ADS)

Phanjom, Probin; Ahmed, Giasuddin

2017-12-01

Synthesis of silver nanoparticles (AgNPs) under different physicochemical conditions like concentration of silver nitrate (AgNO3), pH and temperature, using fungal cell filtrate of Aspergillus oryzae (MTCC No. 1846) and its antibacterial properties were demonstrated. When fungal cell filtrate having neutral pH was exposed to different concentrations of aqueous solution AgNO3 (1-10 mM), formation of stable AgNPs of different sizes was observed. The size of the AgNPs decreased with the increase of AgNO3 concentration from 1 mM to 8 mM, however, the particles size increased with the increase of AgNO3 concentration from 9 mM to 10 mM. When fungal cell filtrate exposed to aqueous solution of 1 mM AgNO3 at different pH (4-10), the silver ions (Ag+) were reduced leading to the formation of stable AgNPs of different sizes. The size of the AgNPs decreased with the increase of alkaline conditions. When aqueous solution of 1mM AgNO3 with fungal cell filtrate, having neutral pH, was exposed to different temperatures (10, 30, 50, 70 and 90 °С), formation of stable AgNPs having different sizes were obtained. The size of the AgNPs decreased with the increase of temperature. Synergetic effect with antibiotics and size dependent antibacterial activities were also demonstrated against Escherichia coli (MTCC 1687), Staphylococcus aureus (MTCC 737), Bacillus subtilis (MTCC 441) and Klebseilla pneumoniae (MTCC 4030). The formation AgNPs was characterized by UV-vis spectrophotometer. Transmission electron microscope (TEM) confirmed the sizes of the obtained nanoparticles. X-ray diffractometer (XRD) spectrum confirmed the formation of metallic silver. The Fourier transform infrared spectroscopy (FTIR) confirmed the presence of protein as stabilizing agent around AgNPs. Scanning electron microscope (TEM) confirmed the morphological changes in the treated bacterial organisms.

Image processing enhancement of high-resolution TEM micrographs of nanometer-size metal particles

NASA Technical Reports Server (NTRS)

Artal, P.; Avalos-Borja, M.; Soria, F.; Poppa, H.; Heinemann, K.

1989-01-01

The high-resolution TEM detectability of lattice fringes from metal particles supported on substrates is impeded by the substrate itself. Single value decomposition (SVD) and Fourier filtering (FFT) methods were applied to standard high resolution micrographs to enhance lattice resolution from particles as well as from crystalline substrates. SVD produced good results for one direction of fringes, and it can be implemented as a real-time process. Fourier methods are independent of azimuthal directions and allow separation of particle lattice planes from those pertaining to the substrate, which makes it feasible to detect possible substrate distortions produced by the supported particle. This method, on the other hand, is more elaborate, requires more computer time than SVD and is, therefore, less likely to be used in real-time image processing applications.

Synthesis, characterization and application of iron (II, III) oxide (Fe3O4) magnetic nanoparticles in mimic of wound healing model

NASA Astrophysics Data System (ADS)

Konyala, Divya

The research study focused on synthesis, characterization and applications of Fe3O4 core-shelled magnetic nanomaterials. This Fe3O4 magnetic nanomaterials will be prepared by using cost effective and convenient wet-chemistry method and will encapsulated using aqueous extracts of medicinal natural products. Three natural products namely Symplocos racemosa, Picrorhiza kurroa and Butea monosperma used to encapsulate Fe3O 4 MNMs due to their scope to reduce the risk of cancer, improves health, increase energy and enhance the immunity. These three medicinal natural products are synthesize by using water as a solvents to derive its active constituents, which will further used to functionalize the magnetic nanomaterials. The magnetic nanoparticles characterization studies performed using X-ray powder diffraction, Scanning electron microscope, Transmission electron microscope, Ultraviolet-visible spectroscopy, Fourier Transform Infrared spectroscopy (FT-IR) and Magnetic property. Fe3O4 magnetic nanomaterials biological activity was tested on Gram-negative bacteria (Escherichia coli). The results pointed out that, due to the adequate coating of Fe 3O4 (Iron Oxide) core by the medicinal chemical constituents from the natural products, the absorption of Fe3O4 magnetic nanomaterials was not detected in the UV-VIS Spectroscopy. TEM images showed that Fe3O4 coated with natural product extract in core-shelled structure, and the size of the particle ranges from 6 nm to 10 nm. Fourier Transform Infrared spectroscopy (FT-IR) was performed to determine the nature of chemicals present in natural extracts and functionalized Fe3O 4 magnetic nanomaterials. The model of wound healing mimic and antibacterial activity performed on gram-negative (Escherichia coli), indicating steady increasing cell growth after adding Fe3O4 MNMs. It was also found that MNMs synthesized at high temperatures shows less wound healing activity, when compared to MNMs prepared at room temperature due to formation of clusters at high temperatures.

Poly-L-lysine/hydroxyapatite/carbon nanotube hybrid nanocomposite applied for piezoelectric immunoassay of carbohydrate antigen 19-9.

PubMed

Ding, Yanjun; Liu, Jia; Jin, Xiaoyong; Lu, Haixia; Shen, Guoli; Yu, Ruqin

2008-02-01

Hybrid composites are of special scientific interest for biochemical applications wherein the abilities to modulate the morphology and property of the hybrid material are important. In this paper, the formation of poly-L-lysine/hydroxyapatite/carbon nanotube (PLL/HA/CNT) hybrid nanoparticles is described and a general design strategy for an immunosensing platform has been proposed on the basis of PLL/HA/CNT nanocomposite adsorption of antibodies. Quartz crystal microbalance (QCM) used as a model transducer and the detection performances of the resulting immunosensor were investigated by use of the immuno-system of carbohydrate antigen 19-9 (CA19-9), an important indicator in the diagnosis of clinical cancers. The hybrid nanocomposite was characterized by the transmission electron microscope (TEM), scanning electron microscope (SEM) and Fourier transform-infrared (FT-IR) spectrum measurements. The frequency response characteristics for the processes of immobilization and immunoreaction of anchored anti-CA19-9 antibodies were studied in detail. It was found that the developed sensing interface has some advantages such as the activation-free immobilization and the high antigen-binding activities of antibodies. The as-prepared immunosensor can allow for the determination of CA19-9 in the concentration range of around 12.5-270.0 U ml(-1). Such an interface design with the hybrid nanocomposite should be tailored as a new alternative used for biosensor design.

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

PubMed

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

2013-10-01

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

Synthesis and characterization of polyaniline/MnWO4 nanocomposites as electrodes for pseudocapacitors

NASA Astrophysics Data System (ADS)

Saranya, S.; Selvan, R. Kalai; Priyadharsini, N.

2012-03-01

Polyaniline (PAni)/MnWO4 nanocomposite was successfully synthesized by in situ polymerization method under ultrasonication and the MnWO4 was prepared by surfactant assisted ultrasonication method. The thermal stability of PAni was determined by TG/DTA (Thermo Gravimetric/ Differential thermal analysis). The structural and morphological features of PAni, MnWO4 and PAni/MnWO4 composite was analyzed using Fourier transform infrared spectrometry, X-ray diffraction (XRD), scanning electron microscope (SEM) and Transmission electron microscope (TEM) images. The electro-chemical properties of PAni, MnWO4 and its composites with different weight percentage of MnWO4 loading were studied through cyclic voltammetry (CV) for the application of supercapacitors as active electrode materials. From the cyclic voltammogram, 50% of MnWO4 impregnated PAni showed a high specific capacitance (SC) of 481 F/g than their individual counterparts of PAni (396 F/g) and MnWO4 (18 F/g). The galvanostatic charge-discharge studies indicate the in situ polymerized composite shows greater specific capacitance (475 F/g) than the physical mixture (346 F/g) at a constant discharge current of 1 mA/cm2 with reasonable cycling stability. The charge transfer resistance (Rct) of PAni/MnWO4 composite (22 ohm) was calculated using electrochemical impedance spectroscopy (EIS) and compared with its physical mixture (58 ohm).

Highly selective adsorption of hydroquinone by hydroxyethyl cellulose functionalized with magnetic/ionic liquid.

PubMed

Ding, Chaofan; Li, Yue; Wang, Yanhui; Li, Jianbo; Sun, Yuanling; Lin, Yanna; Sun, Weiyan; Luo, Chuannan

2018-02-01

Magnetic hydroxyethyl cellulose/ionic liquid (MHEC/IL) materials were fabricated through a facile and fast process and their application as excellent adsorbents for hydroquinone was also demonstrated. The thermal stability, chemical structure and magnetic property of the MHEC/IL were characterized by the Scanning electron microscope (SEM), Transmission Electron Microscope (TEM), Fourier transform infrared spectrometer (FT-IR) and X-ray diffraction (XRD), respectively. The adsorbents were used for the removal of hydroquinone from simulated wastewater with a fast solid-liquid separation in the presence of external magnetic field. The influence of various analytical parameters on the adsorption of hydroquinone such as pH, contact time and initial ion concentration were studied in detail. The results showed that the maximum adsorption capacity was 335.68mgg -1 , observed at pH 5 and temperature 30°C. Equilibrium adsorption was achieved within 30min. The kinetic data, obtained at the optimum pH 5, could be fitted with a pseudo-second order equation. Adsorption process could be well described by Freundlich adsorption isotherms. The obtained results indicated that the impregnation of the room temperature IL significantly enhances the removal efficiency of hydroquinone. The MHEC/IL may be suitable materials in phenols pollution cleanup if they are synthesized in largescale and at low price in near future. Copyright © 2017 Elsevier B.V. All rights reserved.

Microscopic molecular dynamics characterization of the second-order non-Navier-Fourier constitutive laws in the Poiseuille gas flow

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

Rana, A.; Ravichandran, R.; Park, J. H.

The second-order non-Navier-Fourier constitutive laws, expressed in a compact algebraic mathematical form, were validated for the force-driven Poiseuille gas flow by the deterministic atomic-level microscopic molecular dynamics (MD). Emphasis is placed on how completely different methods (a second-order continuum macroscopic theory based on the kinetic Boltzmann equation, the probabilistic mesoscopic direct simulation Monte Carlo, and, in particular, the deterministic microscopic MD) describe the non-classical physics, and whether the second-order non-Navier-Fourier constitutive laws derived from the continuum theory can be validated using MD solutions for the viscous stress and heat flux calculated directly from the molecular data using the statistical method.more » Peculiar behaviors (non-uniform tangent pressure profile and exotic instantaneous heat conduction from cold to hot [R. S. Myong, “A full analytical solution for the force-driven compressible Poiseuille gas flow based on a nonlinear coupled constitutive relation,” Phys. Fluids 23(1), 012002 (2011)]) were re-examined using atomic-level MD results. It was shown that all three results were in strong qualitative agreement with each other, implying that the second-order non-Navier-Fourier laws are indeed physically legitimate in the transition regime. Furthermore, it was shown that the non-Navier-Fourier constitutive laws are essential for describing non-zero normal stress and tangential heat flux, while the classical and non-classical laws remain similar for shear stress and normal heat flux.« less

Microcellular nanocomposite injection molding process

Treesearch

Mingjun Yuan; Lih-Sheng Turng; Rick Spindler; Daniel Caulfield; Chris Hunt

2003-01-01

This study aims to explore the processing benefits and property improvements of combining nanocomposites with microcellular injection molding. The molded parts produced based on the Design of Experiments (DOE) matrices were subjected to tensile testing, impact testing, and Scanning Electron Microscope (SEM), Transmission Electron Microscope (TEM), Dynamic Mechanical...

High-resolution electron microscope

NASA Technical Reports Server (NTRS)

Nathan, R.

1977-01-01

Employing scanning transmission electron microscope as interferometer, relative phases of diffraction maximums can be determined by analysis of dark field images. Synthetic aperture technique and Fourier-transform computer processing of amplitude and phase information provide high resolution images at approximately one angstrom.

Opto-mechano-electrical tripling in ZnO nanowires probed by photocurrent spectroscopy in a high-resolution transmission electron microscope

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

Zhang, C.; Golberg, D., E-mail: xuzhi@iphy.ac.cn, E-mail: golberg.dmitri@nims.go.jp; Graduate School of Pure and Applied Sciences, University of Tsukuba, Tennodai 1, Tsukuba, Ibaraki 3058577

2015-08-31

Photocurrent spectroscopy of individual free-standing ZnO nanowires inside a high-resolution transmission electron microscope (TEM) is reported. By using specially designed optical in situ TEM system capable of scanning tunneling microscopy probing paired with light illumination, opto-mechano-electrical tripling phenomenon in ZnO nanowires is demonstrated. Splitting of photocurrent spectra at around 3.3 eV under in situ TEM bending of ZnO nanowires directly corresponds to nanowire deformation and appearance of expanded and compressed nanowire sides. Theoretical simulation of a bent ZnO nanowire has an excellent agreement with the experimental data. The splitting effect could be explained by a change in the valence band structuremore » of ZnO nanowires due to a lattice strain. The strain-induced splitting provides important clues for future flexible piezo-phototronics.« less

Automated grain mapping using wide angle convergent beam electron diffraction in transmission electron microscope for nanomaterials.

PubMed

Kumar, Vineet

2011-12-01

The grain size statistics, commonly derived from the grain map of a material sample, are important microstructure characteristics that greatly influence its properties. The grain map for nanomaterials is usually obtained manually by visual inspection of the transmission electron microscope (TEM) micrographs because automated methods do not perform satisfactorily. While the visual inspection method provides reliable results, it is a labor intensive process and is often prone to human errors. In this article, an automated grain mapping method is developed using TEM diffraction patterns. The presented method uses wide angle convergent beam diffraction in the TEM. The automated technique was applied on a platinum thin film sample to obtain the grain map and subsequently derive grain size statistics from it. The grain size statistics obtained with the automated method were found in good agreement with the visual inspection method.

Green synthesis and characterization of monodispersed silver nanoparticles using root bark aqueous extract of Annona muricata Linn and their antimicrobial activity

NASA Astrophysics Data System (ADS)

Ezealisiji, K. M.; Noundou, X. S.; Ukwueze, S. E.

2017-11-01

In recent time, various phytosynthetic methods have been employed for the fabrication of silver nanoparticles; these unique metal nanoparticles are used in several applications which include pharmaceuticals and material engineering. The current research reports a rapid and simple synthetic partway for silver nanoparticles (AgNPs) using root bark aqueous extract of Annona muricata and the evaluation of its antimicrobial efficacy against pathogenic microorganisms. The root bark extract was treated with aqueous silver nitrate solution. Silver ions were reduced to silver atoms which on aggregation gave Silver nanoparticles; the biosynthesized AgNPs were characteristically spherical, discreet and stabilized by phytochemical entities and were characterized using ultraviolet visible spectroscopy, transmission electron microscope (TEM) and photon correlation microscopy. The aqueous plant extract-AgNPs suspension was subjected to Fourier transform infrared spectroscopy. TEM result for the average particle size is 22 ± 2 nm. The polydispersity index and zeta-potential were found to be 0.44 ± 0.02 and - 27.90 ± 0.01 mV, respectively (Zeta-Sizer). The antimicrobial evaluation result showed that the synthesized silver nanoparticles at different concentration were very active against the Gram-positive bacteria ( B. subtilis, S. aureous) and Gram-negative bacteria ( K. Pneumonia, E. Coli and Pseudomonas aeruginosa), P. aeruginosa being most susceptible to the anti microbial effect of the silver nanoparticles. Stable silver nanoparticles with antimicrobial activity were obtained through biosynthesis.

Synthesis of SiC nanoparticles by SHG 532 nm Nd:YAG laser ablation of silicon in ethanol

NASA Astrophysics Data System (ADS)

Khashan, Khawla S.; Ismail, Raid A.; Mahdi, Rana O.

2018-06-01

In this work, colloidal spherical nanoparticles NPs of silicon carbide SiC have been synthesized using second harmonic generation 532 nm Nd:YAG laser ablation of silicon target dipped in ethanol solution at various laser fluences (1.5-5) J/cm2. X-Ray diffraction XRD, scanning electron microscopy SEM, transmission electron microscope TEM, Fourier transformed infrared spectroscopy FT-IR, Raman spectroscopy, photoluminescence PL spectroscopy, and UV-Vis absorption were employed to examine the structural, chemical and optical properties of SiC NPs. XRD results showed that all synthesised SiC nanoparticles are crystalline in nature and have hexagonal structure with preferred orientation along (103) plane. Raman investigation showed three characteristic peaks 764,786 and 954 cm-1, which are indexing to transverse optic TO phonon mode and longitudinal optic LO phonon mode of 4H-SiC structure. The optical absorption data showed that the values of optical energy gap of SiC nanoparticles prepared at 1.5 J/cm2 was 3.6 eV and was 3.85 eV for SiC synthesised at 5 J/cm2. SEM investigations confirmed that the nanoparticles synthesised at 5 J/cm2 are agglomerated to form larger particles. TEM measurements showed that SiC particles prepared at 1.5 J/cm2 have spherical shape with average size of 25 nm, while the particles prepared at 5 J/cm2 have an average size of 55 nm.

Preparation of carbon-free TEM microgrids by metal sputtering.

PubMed

Janbroers, S; de Kruijff, T R; Xu, Q; Kooyman, P J; Zandbergen, H W

2009-08-01

A new method for preparing carbon-free, temperature-stable Transmission Electron Microscope (TEM) grids is presented. An 80% Au/20% Pd metal film is deposited onto a 'holey' microgrid carbon supported on standard mixed-mesh Au TEM grids. Subsequently, the carbon film is selectively removed using plasma cleaning. In this way, an all-metal TEM film is made containing the 'same' microgrid as the original carbon film. Although electron transparency of the foil is reduced significantly, the open areas for TEM inspection of material over these areas are maintained. The metal foil can be prepared with various thicknesses and ensures good electrical conductivity. The new Au/Pd grids are stable to at least 775K under vacuum conditions.

CHARACTERISTICS OF INDIVIDUAL PARTICLES AT A RURAL SITE IN THE EASTERN UNITED STATES

EPA Science Inventory

To determine the nature of aerosol particles in a rural area of the eastern United States, aerosol samples were collected at Deep Creek Lake, Maryland, on various substrates and analyzed by a scanning electron microscope (SEM) and a transmission electron microscope (TEM). SEM ana...

DNA translocation measurements in solid-state nanopores fabricated using helium-ion microscope

NASA Astrophysics Data System (ADS)

Liu, Liping; Miao, Wang; Huynh, Chuong; Liu, Quanjun; Ling, Xinsheng

2012-02-01

We report high-quality DNA translocation measurements in solid-state nanopores drilled in free-standing SiN membranes by using a helium-ion beam in a Zeiss helium-ion microscope (HIM). We show that the HIM nanopores have similar performance as the TEM-drilled pores.

Scanning and transmission electron microscopic observation of the parasitic form of Trichophyton violaceum in the infected hair from tinea capitis.

PubMed

Zhuang, Kaiwen; Ran, Xin; Lei, Song; Zhang, Chaoliang; Lama, Jebina; Ran, Yuping

2014-01-01

Trichophyton violaceum is a pathogen of tinea capitis and usually cause infection of scalp and hair in children. To investigate the parasitic form of T. violaceum in the human hair tissue, the infected hair strands were collected from a 9-year-old boy with tinea capitis due to T. violaceum and observed under both the scanning electron microscope (SEM) and transmission electron microscope (TEM). The SEM and TEM findings revealed that T. violaceum parasitically lives in the hair shaft in various forms and the morphological transformation of the fungus from hyphae into arthrospores was noted. The involved hair shaft was damaged to the great extent and its ultrastructural changes were evident. Those morphological characteristics of T. violaceum and the three-dimensional ultastructure changes of infected hairs give a better knowledge about the host-fungus relationship in tinea capitis. © 2014 Wiley Periodicals, Inc.

Scanning electron microscope cathodoluminescence imaging of subgrain boundaries, twins and planar deformation features in quartz

NASA Astrophysics Data System (ADS)

Hamers, M. F.; Pennock, G. M.; Drury, M. R.

2017-04-01

The study of deformation features has been of great importance to determine deformation mechanisms in quartz. Relevant microstructures in both growth and deformation processes include dislocations, subgrains, subgrain boundaries, Brazil and Dauphiné twins and planar deformation features (PDFs). Dislocations and twin boundaries are most commonly imaged using a transmission electron microscope (TEM), because these cannot directly be observed using light microscopy, in contrast to PDFs. Here, we show that red-filtered cathodoluminescence imaging in a scanning electron microscope (SEM) is a useful method to visualise subgrain boundaries, Brazil and Dauphiné twin boundaries. Because standard petrographic thin sections can be studied in the SEM, the observed structures can be directly and easily correlated to light microscopy studies. In contrast to TEM preparation methods, SEM techniques are non-destructive to the area of interest on a petrographic thin section.

Adsorption of methyl orange on mesoporous γ-Fe2O3/SiO2 nanocomposites

NASA Astrophysics Data System (ADS)

Deligeer, W.; Gao, Y. W.; Asuha, S.

2011-02-01

Mesoporous γ-Fe2O3/SiO2 nanocomposite containing 30 mol% of γ-Fe2O3 was prepared by a template-free sol-gel method, and its removal ability for methyl orange (MO) was investigated. The nanocomposite was characterized using X-ray powder diffraction (XRD), transmission electron microscopy (TEM), scanning electron microscope (SEM), Fourier transform infrared (FTIR) absorption measurements, nitrogen adsorption-desorption measurements, and magnetic measurements. The synthesized γ-Fe2O3/SiO2 nanocomposite has a mesoporous structure with an average pore size of 3.5 nm and a specific surface area of 245 m2/g, and it exhibits ferrimagnetic characteristics with the maximum saturation magnetization of 20.9 emu/g. The adsorption of MO on the nanocomposite reaches the maximum adsorbed percentage of ca. 80% within a few minutes, showing that most of MO can be removed in a short time. The MO adsorption data fit well with both Langmuir and Freundlich adsorption isotherms. The maximum adsorption capacity of MO is estimated to be 476 mg/g.

Antibacterial properties of amino acid functionalized silver nanoparticles decorated on graphene oxide sheets

NASA Astrophysics Data System (ADS)

Chandraker, Kumudini; Nagwanshi, Rekha; Jadhav, S. K.; Ghosh, Kallol K.; Satnami, Manmohan L.

2017-06-01

Graphene oxide (GO) sheets decorated with amino acid L-cysteine (L-cys) functionalized silver nanoparticles (GO-L-cys-Ag) was synthesized by AgNO3, trisodium citrate, and NaBH4. GO-L-cys-Ag nanocomposite was characterized by transmission electron microscopy (TEM), Fourier transform infrared (FTIR) spectra, ultraviolet-visible (UV-vis) absorption spectra, which demonstrated that a diameter of L-cys-AgNPs compactly deposited on GO. Antibacterial activity tests of GO-L-cys-Ag nanocomposite were carried out using Escherichia coli MTCC 1687 and Staphylococcus aureus MTCC 3160 as model strains of Gram-negative and Gram-positive bacteria, respectively. The effect of bactericide dosage on antibacterial activity of GO-L-cys-Ag nanocomposite was examined by plate count, well diffusion and broth dilution methods. Morphological observation of bacterial cells by scanning electron microscope (SEM) showed that GO-L-cys-Ag nanocomposite was more destructive to cell membrane of Escherichia coli than that of Staphylococcus aureus. The above technique establish that the bactericidal property of GO-L-cys-Ag nanocomposite with wide range of applications in biomedical science.

Multimodal nanoporous silica nanoparticles functionalized with aminopropyl groups for improving loading and controlled release of doxorubicin hydrochloride.

PubMed

Wang, Xin; Li, Chang; Fan, Na; Li, Jing; He, Zhonggui; Sun, Jin

2017-09-01

The purpose of this study was to develop amino modified multimodal nanoporous silica nanoparticles (M-NSNs-NH 2 ) loaded with doxorubicin hydrochloride (DOX), intended to enhance the drug loading capacity and to achieve controlled release effect. M-NSNs were functionalized with aminopropyl groups through post-synthesis. The contribution of large pore sizes and surface chemical groups on DOX loading and release were systemically studied using transmission electron microscope (TEM), nitrogen adsorption/desorption measurement, Fourier transform infrared spectroscopy (FTIR), zeta potential analysis, X-ray photoelectron spectroscopy (XPS) and ultraviolet spectrophotometer (UV). The results demonstrated that the NSNs were functionalized with aminopropyl successfully and the DOX molecules were adsorbed inside the nanopores by the hydrogen bonding. The release performance indicated that DOX loaded M-NSNs significantly controlled DOX release, furthermore DOX loaded M-NSNs-NH 2 performed slower controlled release, which was mainly attributed to its stronger hydrogen bonding forces. As expected, we developed a novel carrier with high drug loading capacity and controlled release for DOX. Copyright © 2017 Elsevier B.V. All rights reserved.

Synergistic effect on the visible light activity of Ti3+ doped TiO2 nanorods/boron doped graphene composite

PubMed Central

Xing, Mingyang; Li, Xiao; Zhang, Jinlong

2014-01-01

TiO2/graphene (TiO2-x/GR) composites, which are Ti3+ self-doped TiO2 nanorods decorated on boron doped graphene sheets, were synthesized via a simple one-step hydrothermal method using low-cost NaBH4 as both a reducing agent and a boron dopant on graphene. The resulting TiO2 nanorods were about 200 nm in length with exposed (100) and (010) facets. The samples were characterized by X-ray diffraction (XRD), UV-visible diffuse reflectance spectroscopy, X-band electron paramagnetic resonance (EPR), X-ray photoelectron spectra (XPS), transmission electron microscope (TEM), Raman, and Fourier-transform infrared spectroscopy (FTIR). The XRD results suggest that the prepared samples have an anatase crystalline structure. All of the composites tested exhibited improved photocatalytic activities as measured by the degradation of methylene blue and phenol under visible light irradiation. This improvement was attributed to the synergistic effect of Ti3+ self-doping on TiO2 nanorods and boron doping on graphene. PMID:24974890

Optical and structure characterization of cinnamon nanoparticles synthesized by pulse laser ablation in liquid (PLAL)

NASA Astrophysics Data System (ADS)

Aqeel Salim, Ali; Bidin, Noriah; Bakhtiar, Hazri; Krishna Ghoshal, Sib; Azawi, Mohammed Al; Krishnan, Ganesan

2018-05-01

Organic nanoparticles development is under exploration due to its beneficial applications in nanobiomedical and research interests. PLAL technique of Q-switched 1064-Nd: YAG (10 ns pulse duration, repetition rate 1 Hz and laser energy 20-100 mJ) has inherent advantages and rapid growth of nanoparticles when compared to conventional methods because of the controlled fabricated nanoparticles, stability, and purity. Cinnamon sticks as a target are immersed in 5 ml ethanol medium and irradiated by a laser beam for the growth process. The morphology, optical characteristic, and bonding structure of cinnamon nanoparticles (CNPs) are determined and evaluated by transmission electron microscope (TEM), UV-Visible spectroscopy and Fourier transform infrared spectroscopy (FTIR). Spherical, homogenous and high crystallinity CNPs was revealed within the particle size range of 2 - 28 nm. The absorption band was found in the ultraviolent region around 259 nm and 319 nm. The present of FTIR spectra confirmed that the nanoparticles were covered by plant secondary metabolites. The experimental findings revealed that the synthesize CNPs in ethanol has a potential for nanomedicine applications.

Enhancement of antioxidant and antibacterial properties for tannin acid/chitosan/tripolyphosphate nanoparticles filled electrospinning films: Surface modification of sliver nanoparticles.

PubMed

Zhan, Fuchao; Sheng, Feng; Yan, Xiangxing; Zhu, Yingrui; Jin, Weiping; Li, Jing; Li, Bin

2017-11-01

The tannin acid/chitosan/tripolyphosphate nanoparticles were encapsulated in polyvinyl alcohol (PVA)/poly-acrylic acid (PAA) electrospinning films by electrostatic spinning technology. To optimize the prepared condition, properties and morphology of nanoparticles were characterized by dynamic light scattering (DLS) and transmission electron microscope (TEM). The optimized initial concentration of tannin, chitosan and tripolyphosphate solutions were 1, 1, 0.5mg/ml, respectively, with adding proportion for 5:5:1. The average diameter of tannin acid/chitosan/tripolyphosphate nanoparticles was ∼80nm. The electrospinning films showed an excellent water-resistant property with 0.5wt%N,N'-Methylenebisacrylamide (MBA). Due to the antioxidant and antibacterial of tannic acid, the films possessed these properties. The antioxidant and antibacterial of these fibers significantly improved after in situ formation of silver nanoparticles (AgNPs). Electrospun films were characterized by scanning electron microscopy (SEM), Fourier transform infrared spectra (FT-IR), X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS). Copyright © 2017 Elsevier B.V. All rights reserved.

Plant-mediated synthesis of silver nanoparticles using parsley ( Petroselinum crispum) leaf extract: spectral analysis of the particles and antibacterial study

NASA Astrophysics Data System (ADS)

Roy, Kaushik; Sarkar, C. K.; Ghosh, C. K.

2015-12-01

Synthesis of nanomaterials may involve various routes including physical, chemical and biological approaches. Here, the biological green route was chosen to prepare silver nanoparticles from silver salts to avoid the requirement of costly instruments and involvement of hazardous chemicals as well. To make the process clean and green, leaf extract of parsley ( Petroselinum crispum) was used to synthesize Ag nanoparticles at room temperature. The formation of Ag-nanoparticles was monitored by UV-Vis spectroscopy. The presence of silver in the sample and its crystalline nature were verified by X-ray diffraction (XRD) analysis. The size distribution profile and particle size in the suspension were manipulated from dynamic light scattering (DLS) pattern. The shape, size and morphology of the biogenic nanoparticles were studied using high resolution transmission electron microscope (TEM). Fourier transform infra-red spectroscopy was used to detect the biomolecules responsible for reduction of silver ions. These biogenic Ag-nanoparticles showed appreciable antibacterial efficacy against three bacteria— Klebsiella pneumoniae, Escherichia coli and Staphylococcus aureus.

Gamma radiation mediated green synthesis of gold nanoparticles using fermented soybean-garlic aqueous extract and their antimicrobial activity.

PubMed

El-Batal, Ahmed Ibrahim; Hashem, Abd-Algawad M; Abdelbaky, Noha M

2013-12-01

Aspergillus oryzae was used to enhance the mobilization of antioxidants of soybean matrix along with garlic as a co-substrate by modulating polyphenolic substances during solid-state fermentation. Mobilized polyphenols were used as a green tool for synthesis and stabilization of gold nanoparticles (AuNPs). The radiation-induced AuNPs synthesis is a simple, clean and inexpensive process which involves radiolysis of aqueous solution that provides an efficient method to reduce metal ions. Gamma irradiated aqueous extract of fermented soybean and garlic was used for rapid preparation of AuNPs combining both effects of radiolytic reactions by radiation and stabilization by bioactive components of fermented extract. The synthesized AuNPs were confirmed by UV-Visible spectrophotometry, dynamic light scattering (DLS), Fourier Transform infra red (FT-IR) spectrophotometry, and transmission electron microscope (TEM) analysis which revealed morphology of spherical AuNPs with size ranging from 7-12 nm. The synthesized AuNPs exhibited antimicrobial activity against both Gram positive and Gram negative bacteria, as measured by well diffusion assay.

Purchase of a Transmission Electron Microscope for Xavier University of Louisiana

DTIC Science & Technology

2015-05-15

imaging facility on the second floor of the Pharmacy Addition at Xavier University that already includes two scanning electron microscopes. The new TEM...is now in use. Xavier University has formally pledged to provide funds for the 1. REPORT DATE (DD-MM-YYYY) 4. TITLE AND SUBTITLE 13. SUPPLEMENTARY...for Public Release; Distribution Unlimited Final Report: Purchase of a Transmission Electron Microscope for Xavier University of Louisiana The views

Localised corrosion in aluminium alloy 2024-T3 using in situ TEM.

PubMed

Malladi, Sairam; Shen, Chenggang; Xu, Qiang; de Kruijff, Tom; Yücelen, Emrah; Tichelaar, Frans; Zandbergen, Henny

2013-11-28

An approach to carry out chemical reactions using aggressive gases in situ in a transmission electron microscope (TEM), at ambient pressures of 1.5 bar using a windowed environmental cell, called a nanoreactor, is presented here. The nanoreactor coupled with a specially developed holder with platinum tubing permits the usage of aggressive chemicals like hydrochloric acid (HCl).

Three-dimensional cytomorphology in fine needle aspiration biopsy of medullary thyroid carcinoma.

PubMed

Chang, T C; Lai, S M; Wen, C Y; Hsiao, Y L; Huang, S H

2001-01-01

To elucidate three-dimensional (3-D) cytomorphology in fine needle aspiration biopsy (FNAB) of medullary thyroid carcinoma (MTC). ENAB was performed on tumors from five patients with MTC. The aspirate was stained and observed under a light microscope (LM). The aspirate was also fixed, dehydrated, critical point dried, spattered with gold ions and observed with a scanning electron microscope (SEM). For transmission electron microscopy (TEM), the specimen was fixed, dehydrated, embedded in an Epon mixture, cut with an ultramicrotome, mounted on copper grids, electron doubly stained with uranium acetate and lead citrate, and observed with TEM. Findings under SEM were correlated with those under LM and TEM. Under SEM, 3-D cytomorphology of MTC displayed a disorganized cellular arrangement with indistinct cell borders in three cases. The cell surface was uneven and had granular protrusions that corresponded to secretory granules observed under TEM. In one case with multiple endocrine neoplasia type IIB, there were abundant granules on the cell surface. In one case of sporadic MTC with multinucleated tumor giant cells and small cells, granular protrusions also were noted on the cell surface. Granular protrusion was a characteristic finding in FNAB of MTC tinder SEM and might be helpful in the differential diagnosis.

Design of a 300-kV gas environmental transmission electron microscope equipped with a cold field emission gun.

PubMed

Isakozawa, Shigeto; Nagaoki, Isao; Watabe, Akira; Nagakubo, Yasuhira; Saito, Nobuhiro; Matsumoto, Hiroaki; Zhang, Xiao Feng; Taniguchi, Yoshifumi; Baba, Norio

2016-08-01

A new in situ environmental transmission electron microscope (ETEM) was developed based on a 300 kV TEM with a cold field emission gun (CFEG). Particular caution was taken in the ETEM design to assure uncompromised imaging and analytical performance of the TEM. Because of the improved pumping system between the gun and column, the vacuum of CFEG was largely improved and the probe current was sufficiently stabilized to operate without tip flashing for 2-3 h or longer. A high brightness of 2.5 × 10(9) A/cm(2) sr was measured at 300 kV, verifying the high quality of the CFEG electron beam. A specially designed gas injection-heating holder was used in the in situ TEM study at elevated temperatures with or without gas around the TEM specimen. Using this holder in a 10 Pa gas atmosphere and specimen temperatures up to 1000°C, high-resolution ETEM performance and analysis were achieved. © The Author 2016. Published by Oxford University Press on behalf of The Japanese Society of Microscopy. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

Structural refinement, band-gap analysis and optical properties of GdAlO3 nanophosphors influenced by Dy3+ ion concentrations for white light emitting device applications

NASA Astrophysics Data System (ADS)

Jisha, P. K.; Naik, Ramachandra; Prashantha, S. C.; Nagaswarupa, H. P.; Nagabhushana, H.; Basavaraj, R. B.; Sharma, S. C.; Prasad, Daruka

2016-04-01

Nanosized GdAlO3 phosphors activated with Dy3+ were prepared by a combustion method. Synthesized phosphors were calcined at 1000 °C for 3 h in order to achieve crystallinity. Powder x-ray diffraction (XRD), scanning electron microscope (SEM) and transmission electron microscope (TEM) analysis was used to characterize the prepared product. The orthorhombic phase was observed in the XRD pattern. The particle size of the samples was calculated as around 25 nm. The SEM images show an irregular shape of the prepared nanophosphor. Functional groups of the phosphors were examined by Fourier transform infrared (FTIR) spectroscopy. Photoluminescence (PL) properties of Dy3+ doped GdAlO3 for near-ultraviolet excitation (352 nm) were studied in order to investigate the possibility of its use in white light emitting device applications. Judd-Ofelt intensity parameters, radiative transition rate (A T) and radiative lifetimes (τ rad) were evaluated from the emission spectrum by adopting a standard procedure. The Commission International de l’Eclairage (CIE) color coordinates and correlated color temperature (CCT) are studied for the optimized phosphor. It is found that the color coordinates of Dy3+ doped GdAlO3 powders fall in the white region of the CIE diagram, and the average CCT value was found to be about 6276 K. Therefore, the present phosphor is highly useful for display applications.

Luminescent and transparent nanopaper based on rare-earth up-converting nanoparticle grafted nanofibrillated cellulose derived from garlic skin.

PubMed

Zhao, Jingpeng; Wei, Zuwu; Feng, Xin; Miao, Miao; Sun, Lining; Cao, Shaomei; Shi, Liyi; Fang, Jianhui

2014-09-10

Highly flexible, transparent, and luminescent nanofibrillated cellulose (NFC) nanopaper with heterogeneous network, functionalized by rare-earth up-converting luminescent nanoparticles (UCNPs), was rapidly synthesized by using a moderate pressure extrusion paper-making process. NFC was successfully prepared from garlic skin using an efficient extraction approach combined with high frequency ultrasonication and high pressure homogenization after removing the noncellulosic components. An efficient epoxidation treatment was carried out to enhance the activity of the UCNPs (NaYF4:Yb,Er) with oleic acid ligand capped on the surface. The UCNPs after epoxidation then reacted with NFC in aqueous medium to form UCNP-grafted NFC nanocomposite (NFC-UCNP) suspensions at ambient temperature. Through the paper-making process, the assembled fluorescent NFC-UCNP hybrid nanopaper exhibits excellent properties, including high transparency, strong up-conversion luminescence, and good flexibility. The obtained hybrid nanopaper was characterized by transmission electron microscopy (TEM), atomic force microscope (AFM), Fourier transform infrared spectroscopy (FTIR), field emission-scanning electron microscope (FE-SEM), up-conversion luminescence (UCL) spectrum, and ultraviolet and visible (UV-vis) spectrophotometer. The experimental results demonstrate that the UCNPs have been successfully grafted to the NFC matrix with heterogeneous network. And the superiorly optical transparent and luminescent properties of the nanopaper mainly depend on the ratio of UCNPs to NFC. Of importance here is that, NFC and UCNPs afford the nanopaper a prospective candidate for multimodal anti-counterfeiting, sensors, and ion probes applications.

Conservation of Monuments by a Three-Layered Compatible Treatment of TEOS-Nano-Calcium Oxalate Consolidant and TEOS-PDMS-TiO₂ Hydrophobic/Photoactive Hybrid Nanomaterials.

PubMed

Kapridaki, Chrysi; Verganelaki, Anastasia; Dimitriadou, Pipina; Maravelaki-Kalaitzaki, Pagona

2018-04-27

In the conservation of monuments, research on innovative nanocomposites with strengthening, hydrophobic and self-cleaning properties have attracted the interest of the scientific community and promising results have been obtained as a result. In this study, stemming from the need for the compatibility of treatments in terms of nanocomposite/substrate, a three-layered compatible treatment providing strengthening, hydrophobic, and self-cleaning properties is proposed. This conservation approach was implemented treating lithotypes and mortars of different porosity and petrographic characteristics with a three-layered treatment comprising: (a) a consolidant, tetraethoxysilane (TEOS)-nano-Calcium Oxalate; (b) a hydrophobic layer of TEOS-polydimethylsiloxane (PDMS); and (c) a self-cleaning layer of TiO₂ nanoparticles from titanium tetra-isopropoxide with oxalic acid as hole-scavenger. After the three-layered treatment, the surface hydrophobicity was improved due to PDMS and nano-TiO₂ in the interface substrate/atmosphere, as proven by the homogeneity and the Si⁻O⁻Ti hetero-linkages of the blend protective/self-cleaning layers observed by Scanning Electron Microscope (SEM), Transmission Electron Microscope (TEM) and Fourier-Transform Infrared Spectroscopy (FTIR). The aesthetic, microstructural, mechanical and permeabile compatibility of the majority of treated substrates ranged within acceptability limits. The improved photocatalytic activity, as proven by the total discoloration of methylene blue in the majority of cases, was attributed to the anchorage of TiO₂, through the Si⁻O⁻Ti bonds to SiO₂, in the interface with the atmosphere, thus enhancing photoactivation.

Biocompatibility assessment of graphene oxide-hydroxyapatite coating applied on TiO2 nanotubes by ultrasound-assisted pulse electrodeposition.

PubMed

Fathyunes, Leila; Khalil-Allafi, Jafar; Sheykholeslami, Seyed Omid Reza; Moosavifar, Maryam

2018-06-01

In this study, the ultrasound-assisted pulse electrodeposition was introduced to fabricate the graphene oxide (GO)-hydroxyapatite (HA) coating on TiO 2 nanotubes. The results of the X-ray diffraction (XRD), Fourier Transform Infrared spectroscope (FTIR), Transmission Electron Microscope (TEM) and micro-Raman spectroscopy showed the successful synthesis of GO. The Scanning Electron Microscope (SEM) images revealed that in the presence of ultrasonic waves and GO sheets a more compact HA-based coating with refined microstructure could be formed on the pretreated titanium. The results of micro-Raman analysis confirmed the successful incorporation of the reinforcement filler of GO into the coating electrodeposited by the ultrasound-assisted method. The FTIR analysis showed that the GO-HA coating was consisted predominantly of the B-type carbonated HA (CHA) phase. The pretreatment of the substrate and incorporation of the GO sheets into the HA coating had a significant effect on improving the bonding strength at the coating-substrate interface. Moreover, the results of the fibroblast cell culture and 3‑(4,5‑dimethylthiazolyl‑2)‑2, 5‑diphenyltetrazolium bromide (MTT) assay after 2 days demonstrated a higher percentage of cell activity for the GO-HA coated sample. Finally, the 7-day exposure to simulated body fluid (SBF) showed a faster rate of apatite precipitation on the GO-HA coating, as compared to the HA coating and pretreated titanium. Copyright © 2018 Elsevier B.V. All rights reserved.

TiO2 nanoparticles versus TiO2-SiO2 nanocomposites: A comparative study of photo catalysis on acid red 88

NASA Astrophysics Data System (ADS)

Balachandran, K.; Venckatesh, Rajendran; Sivaraj, Rajeshwari; Rajiv, P.

2014-07-01

A novel, simple, less time-consuming and cost-effective wet chemical technique was used to synthesis TiO2 nanoparticles and TiO2-SiO2 nanocomposites using Titanium tetra isopropoxide (TTIP) as a precursor relatively at low temperature in acidic pH. Titania sol was prepared by hydrolysis of TTIP and was mixed with silicic acid and tetrahydrofuran mixture. The reaction was carried out under vigorous stirring for 6 h and dried at room temperature. The resulting powders were characterized by UV-Visible spectroscopy, Fourier transform infrared (FT-IR), X-ray diffraction, scanning electron microscope (SEM) and transmission electron microscope (TEM). The grain size of the particles was calculated by X-ray diffraction, surface morphology and chemical composition was determined from scanning electron microscopy-energy dispersive spectroscopy, metal oxide stretching was confirmed from FT-IR spectroscopy, band gap was calculated using UV-Visible spectroscopy. Surface area of the composite as calculated by BET analyzer and it was found to be 65 and 75 m2/g for TiO2 and TiO2-SiO2 respectively. The photocatalytic experiments were performed with aqueous solution of acid red 88 with TiO2 and TiO2-SiO2 batch studies for 4 h irradiation, direct photolysis of TiO2 and TiO2-SiO2 contributed 94.2% and 96.5% decomposition in solar radiation for the optimized concentration of acid red 88.

Formation of the YBa2Cu2NbOy Phase in Thin Films (POSTPRINT)

DTIC Science & Technology

2010-03-01

protective layer was deposited on the top of YBCNO film by dc sputtering . A 200 nm 200 nm area film was selected and cut with a Ga ion beam (30 kV...200 TEM at 200 kV. Samples for TEM were prepared using a focused ion beam (FIB (Eindhoven, The Netherlands)) microscope. For TEM examination, a thin Pt...by dc magnetron sputtering deposition of Ag with 93 mm thickness. Transport current measurements were made in liquid nitrogen with the 4-probe method

Glucose biosensor based on GOx/HRP bienzyme at liquid-crystal/aqueous interface.

PubMed

Khan, Mashooq; Park, Soo-Young

2015-11-01

Glucose oxidase (GOx) and horseradish peroxidase (HRP) were co-immobilized to the polyacrylicacid block of a poly(acrylicacid-b-4-cyanobiphenyl-4'-undecylacrylate) (PAA-b-LCP) copolymer in water. PAA-b-LCP was strongly anchored by the LCP block in 4-cyano-4'-pentylbiphenyl (5CB) which was contained in a transmission electron microscope (TEM) grid for glucose detection. The optimal conditions for the performance of the TEM grid glucose biosensor were studied in terms of the activity and stability of the immobilized enzymes. Glucose in water was detected by the 5CB changing from a planar to a homeotropic orientation, as observed through a polarized optical microscope. The TEM biosensor detected glucose concentrations at ⩾0.02 mM, with an optimal GOx/HRP molar ratio of 3/1. This glucose biosensor has characteristics of enzyme sensitivity and stability, reusability, the ease and selective glucose detection which may provide a new way of detecting glucose. Copyright © 2015 Elsevier Inc. All rights reserved.

Dopant concentration dependent growth of Fe:ZnO nanostructures

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

Sahai, Anshuman; Goswami, Navendu, E-mail: navendugoswami@gmail.com

2016-05-23

Systematic investigations of structural properties of 1-10% Fe doped ZnO nanostructure (Fe:ZnO NS) prepared via chemical precipitation method have been reported. Structural properties were probed thoroughly employing scanning electron microscope (SEM) and transmission electron microscope (TEM), energy dispersive X-ray (EDAX) analysis and X-ray diffraction (XRD). Morphological transformation of nanostructures (NS) with Fe incorporation is evident in SEM/TEM images. Nanoparticles (NP) obtained with 1% Fe, evolve to nanorods (NR) for 3% Fe; NR transform to nanocones (NC) (for 5% and 7% Fe) and finally NC transform to nanoflakes (NF) at 10% Fe. Morover, primary phase of Zn{sub 1-x}Fe{sub x}O along withmore » secondary phases of ZnFe{sub 2}O{sub 4} and Fe{sub 2}O{sub 3} were also revealed through XRD measurements. Based on collective XRD, SEM, TEM, and EDAX interpretations, a model for morphological evolution of NS was proposed and the pivotal role of Fe dopant was deciphered.« less

[In vivo study on influence of a discrete nano-hydroxyapatite on leukemia P388 tissue in BALB/C mice].

PubMed

Li, Ge; Huang, Jian-ming; Aoki, Hideki; Li, Yan; Zhang, Rong; Deng, Bi-fang

2007-09-01

To study the influence of a discrete nano-hydroxyapatite crystal (nano-HAp) on lymphatic leukemia P388 behavior by in vivo techniques. A nano-HAp was prepared by a neutralization reaction of 0.1 mol calcium hydroxide suspension and 0.06 mol phosphoric acid solutions at room temperature over pH7. The various doses of the nano-HAp only and the nano-HAp mixture with cyclophosphamide (CY) were injected into mice inoculated with solid tumor lymphatic leukemia P388 and dispersed into PRMI 1640 media harvested the leukemia P388 cells. Sixty P388 BALB/C mice were randomly grouped; 36 of them were used as nano-HAp treated groups and 24 mice as the control groups. The leukemia growth in the mice was examined morphologically, histopathologically and under a transmission electron microscope (TEM). The nano-HAp was identified as a hydroxyapatite by an X-ray diffractometry (XRD) and a Fourier transform infrared spectroscopy (FTIR). The morphology and sizes were observed under a TEM. The tissue growth inhibition ratio (weight%) of solid lymphatic leukemia P388 bearing mice treated with nano-HAp at doses 35 mg/kg, 53 mg/kg and nano-HAp (53 mg/kg) combined with CY (35 mg/kg) in 3 consecutive days via intraperitineal injections were 14.95%, 32.67% and 60.45% respectively. Apoptosis of P388 cell cocultured with nano-HAp was confirmed by TEM. The tissue growth restriction of solid tumor lymphatic leukemia P388 was greater after an injection of nano-HAp only or nano-HAp mixed with CY than that obtained after injection with physiological saline solution as a control (P < 0.01), and the tissue growth restriction of solid tumor after an injection of nano-HAp combined with CY was greater than that obtained after nano-HAp or CY injection only (P < 0.01).

Remote microscopy and volumetric imaging on the surface of icy satellites

NASA Astrophysics Data System (ADS)

Soto, Alejandro; Nowicki, Keith; Howett, Carly; Feldkhun, Daniel; Retherford, Kurt D.

2017-10-01

With NASA PIDDP support we have applied recent advancements in Fourier-domain microscopy to develop an instrument capable of microscopic imaging from meter-scale distances for use on a planetary lander on the surface of an icy satellite or other planetary bodies. Without moving parts, our instrument projects dynamic patterns of laser light onto a distant target using a lightweight large-aperture reflector, which then collects the light scattered or fluoresced by the target on a fast photon-bucket detector. Using Fourier Transform based techniques, we reconstruct an image from the detected light. The remote microscope has been demonstrated to produce 2D images with better than 15 micron lateral resolution for targets at a distance of 5 meters and is capable of linearly proportionally higher resolution at shorter distances. The remote microscope is also capable of providing three-dimensional (3D) microscopic imaging capabilities, allowing future surface scientists to explore the morphology of microscopic features in surface ices, for example. The instrument enables microscopic in-situ imaging during day or night without the use of a robotic arm, greatly facilitating the surface operations for a lander or rover while expanding the area of investigation near a landing site for improved science targeting. We are developing this remote microscope for in-situ planetary exploration as a collaboration between the Southwest Research Institute, LambdaMetrics, and the University of Colorado.

Microscopic and spectroscopic characterization of humic substances from a compost amended copper contaminated soil: main features and their potential effects on Cu immobilization.

PubMed

Medina, Jorge; Monreal, Carlos; Chabot, Denise; Meier, Sebastián; González, María Eugenia; Morales, Esteban; Parillo, Rita; Borie, Fernando; Cornejo, Pablo

2017-06-01

We characterized humic substances (HS) extracted from a Cu-contaminated soil without compost addition (C) or amended with a wheat straw-based compost (WSC) (H1), co-composted with Fe 2 O 3 (H2), or co-composted with an allophane-rich soil (H3). Extracted HS were characterized under electron microscopy (SEM/TEM), energy-dispersive X-ray (X-EDS), and Fourier transform infrared (FTIR) spectroscopy. In addition, HS extracted from WSC (H4) were characterized at pH 4.0 and 8.0 with descriptive purposes. At pH 4.0, globular structures of H4 were observed, some of them aggregating within a large network. Contrariwise, at pH 8.0, long tubular and disaggregated structures prevailed. TEM microscopy suggests organo-mineral interactions at scales of 1 to 200 nm with iron oxide nanoparticles. HS extracted from soil-compost incubations showed interactions at nanoscale with minerals and crystal compounds into the organic matrix of HS. Bands associated to acidic functional groups of HS may suggest potential sorption interactions with transition metals. We conclude that metal ions and pH have an important role controlling the morphology and configuration of HS from WSC. Characterization of H4 extracted from WSC showed that physicochemical protection of HS could be present in composting systems treated with inorganic materials. Finally, the humified fractions obtained from compost-amended soils may have an important effect on metal-retention, supporting their potential use in metal-contaminated soils.

Synthesis and characterization of Ag@polycarbazole coaxial nanocables and their enhanced dispersion behavior

NASA Astrophysics Data System (ADS)

Zahoor, Ahmad; Teng, Qiu; Wang, Haiqiao; Choudhry, M. A.; Li, Xiaoyu

2011-06-01

Ag@polycarbazole coaxial nanocables (CNCs) have been successfully fabricated by the oxidative polymerization of carbazole over Ag nanowires (NWs) in acetonitrile. The morphology of Ag NWs and CNCs was studied by employing a transmission electron microscope (TEM) and a scanning electron microscope (SEM), which showed them to be a monodisperse material. The thickness of the polymer sheath was found to be 5 nm to 8 nm by observation under a high-resolution transmission electron microscope (HR-TEM). Energy dispersive X-ray spectroscopy (EDS), FT-IR and Raman measurements were used to characterize the polymer sheath, which demonstrated it to be a carbon material in polycarbazole form. X-ray photoelectron spectroscopy (XPS) was used for an interfacial study, which revealed that Ag surface atoms remained intact during polymer growth. In the end, zeta potential showed that the dispersion stability of Ag NWs increased due to polymer encapsulation, which is significant to obtain a particular alignment for anisotropic measurement of electrical conductivity.

Growing Carbon Nanotubes

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

None

In situ transmission electron microscope (TEM) video (accelerated 10 times) of nucleation and self-organization of a high-density carbon nanotube network from catalytic iron nanoparticles, forming a vertically aligned forest.

Structural analysis of ion-implanted chemical-vapor-deposited diamond by transmission electron microscope

NASA Astrophysics Data System (ADS)

Jiang, N.; Deguchi, M.; Wang, C. L.; Won, J. H.; Jeon, H. M.; Mori, Y.; Hatta, A.; Kitabatake, M.; Ito, T.; Hirao, T.; Sasaki, T.; Hiraki, A.

1997-04-01

A transmission electron microscope (TEM) study of ion-implanted chemical-vapor-deposited (CVD) diamond is presented. CVD diamond used for transmission electron microscope observation was directly deposited onto Mo TEM grids. As-deposited specimens were irradiated by C (100 keV) ions at room temperature with a wide range of implantation doses (10 12-10 17/cm 2). Transmission electron diffraction (TED) patterns indicate that there exists a critical dose ( Dc) for the onset of amorphization of CVD diamond as a result of ion induced damage and the value of critical dose is confirmed to be about 3 × 10 15/cm 2. The ion-induced transformation process is clearly revealed by high resolution electron microscope (HREM) images. For a higher dose implantation (7 × 10 15/cm 2) a large amount of diamond phase is transformed into amorphous carbon and many tiny misoriented diamond blocks are found to be left in the amorphous solid. The average size of these misoriented diamond blocks is only about 1-2 nm. Further bombardment (10 17/cm 2) almost kills all of the diamond phase within the irradiated volume and moreover leads to local formation of micropolycrystalline graphite.

Strain mapping in TEM using precession electron diffraction

DOEpatents

Taheri, Mitra Lenore; Leff, Asher Calvin

2017-02-14

A sample material is scanned with a transmission electron microscope (TEM) over multiple steps having a predetermined size at a predetermined angle. Each scan at a predetermined step and angle is compared to a template, wherein the template is generated from parameters of the material and the scanning. The data is then analyzed using local mis-orientation mapping and/or Nye's tensor analysis to provide information about local strain states.

Solar Flare Track Exposure Ages in Regolith Particles: A Calibration for Transmission Electron Microscope Measurements

NASA Technical Reports Server (NTRS)

Berger, Eve L.; Keller, Lindsay P.

2015-01-01

Mineral grains in lunar and asteroidal regolith samples provide a unique record of their interaction with the space environment. Space weathering effects result from multiple processes including: exposure to the solar wind, which results in ion damage and implantation effects that are preserved in the rims of grains (typically the outermost 100 nm); cosmic ray and solar flare activity, which result in track formation; and impact processes that result in the accumulation of vapor-deposited elements, impact melts and adhering grains on particle surfaces. Determining the rate at which these effects accumulate in the grains during their space exposure is critical to studies of the surface evolution of airless bodies. Solar flare energetic particles (mainly Fe-group nuclei) have a penetration depth of a few millimeters and leave a trail of ionization damage in insulating materials that is readily observable by transmission electron microscope (TEM) imaging. The density of solar flare particle tracks is used to infer the length of time an object was at or near the regolith surface (i.e., its exposure age). Track measurements by TEM methods are routine, yet track production rate calibrations have only been determined using chemical etching techniques [e.g., 1, and references therein]. We used focused ion beam-scanning electron microscope (FIB-SEM) sample preparation techniques combined with TEM imaging to determine the track density/exposure age relations for lunar rock 64455. The 64455 sample was used earlier by [2] to determine a track production rate by chemical etching of tracks in anorthite. Here, we show that combined FIB/TEM techniques provide a more accurate determination of a track production rate and also allow us to extend the calibration to solar flare tracks in olivine.

Extending Single-Molecule Microscopy Using Optical Fourier Processing

PubMed Central

2015-01-01

This article surveys the recent application of optical Fourier processing to the long-established but still expanding field of single-molecule imaging and microscopy. A variety of single-molecule studies can benefit from the additional image information that can be obtained by modulating the Fourier, or pupil, plane of a widefield microscope. After briefly reviewing several current applications, we present a comprehensive and computationally efficient theoretical model for simulating single-molecule fluorescence as it propagates through an imaging system. Furthermore, we describe how phase/amplitude-modulating optics inserted in the imaging pathway may be modeled, especially at the Fourier plane. Finally, we discuss selected recent applications of Fourier processing methods to measure the orientation, depth, and rotational mobility of single fluorescent molecules. PMID:24745862

Extending single-molecule microscopy using optical Fourier processing.

PubMed

Backer, Adam S; Moerner, W E

2014-07-17

This article surveys the recent application of optical Fourier processing to the long-established but still expanding field of single-molecule imaging and microscopy. A variety of single-molecule studies can benefit from the additional image information that can be obtained by modulating the Fourier, or pupil, plane of a widefield microscope. After briefly reviewing several current applications, we present a comprehensive and computationally efficient theoretical model for simulating single-molecule fluorescence as it propagates through an imaging system. Furthermore, we describe how phase/amplitude-modulating optics inserted in the imaging pathway may be modeled, especially at the Fourier plane. Finally, we discuss selected recent applications of Fourier processing methods to measure the orientation, depth, and rotational mobility of single fluorescent molecules.

Evolution of the magnesium incorporated amorphous calcium phosphate to nano-crystallized hydroxyapatite in alkaline solution

NASA Astrophysics Data System (ADS)

Zhang, Xiao-Juan; Lin, Dong-Yang; Yan, Xiao-Hui; Wang, Xiao-Xiang

2011-12-01

A homogeneous amorphous calcium phosphate (ACP) coating containing magnesium was achieved on titanium substrates by electrochemical deposition (ECD). Its amorphous structure is confirmed by transmission electron microscope (TEM) together with grazing reflection absorption infrared spectroscopy (IR) spectrometer. In the images of high-resolution transmission electron microscope (HRTEM), the ACP spheres are assembled by nano-particles with the diameter of 5-10 nm. In the alkaline environment, nucleation of hydroxyapatite (HAP) occurs on the surfaces of ACP spheres. By consuming the Ca and PO 4 ions inside the ACP spheres, the HAP nuclei grow outward. Confirmed by TEM, the ACP spheres converse to hollow HAP spheres composed of HAP nano-needles. The coating is finally constructed by the HAP nano-needles, which are themselves aggregated by numerous nano-particles.

Report on the Installation and Preparedness of a Protochips Fusion in-situ Heating Holder for TEM

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

Edmondson, Philip D.

2017-03-01

This brief report documents the procurement and installation of a Protochips Fusion (formerly Aduro) high-temperature, high stability transmission electron microscopy (TEM) specimen holder that allows for the high spatial resolution characterization of material specimens at high temperature in situ of an electron microscope. This specimen holder was specifically procured for use with The FEI Talos F200X Scanning/Transmission Electron Microscope (STEM) in Oak Ridge National Laboratory’s (ORNL’s) Low Activation Materials Development and Analysis (LAMDA) Laboratory. The Protochips Fusion holder will enable high-resolution structural and chemical analysis of irradiated materials at high temperature, becoming a unique capability worldwide, and would encourage high-qualitymore » in situ experiments to be conducted on irradiated materials.« less

Studying dynamic processes in liquids by TEM/STEM/DTEM

NASA Astrophysics Data System (ADS)

Abellan, Patricia; Evans, James; Woehl, Taylor; Jungjohann, Katherine; Parent, Lucas; Arslan, Ilke; Ristenpart, William; Browning, Nigel; Mater. Sci. Group Team; Microsc. Group Team; Catal. Sci. Group Collaboration; Ristenpart Res. Group Collaboration

2013-03-01

In order to study dynamic phenomena such as corrosion or catalysis, extreme environmental conditions must be reproduced around the specimen - these include high-temperatures, high-pressures, specific oxidizing/reducing atmospheres or a liquid environment. The use of environmental stages specifically designed to fit in any transmission electron microscope (TEM) allows us to apply the distinct capabilities of each instrument to study dynamic processes. Localized gas/fluid conditions are created around the sample and separated from the high vacuum inside the microscope using hermetically sealed windowed-cells. Advanced capabilities of these techniques include spatial resolutions of ~1 Angstrom or better in aberration corrected instruments or temporal resolutions in the microsecond-nanosecond range in a dynamic TEM (DTEM). Here, unique qualities of the DTEM that benefit the in-situ experiments with gas/fluid environmental cells will be discussed. We also present our results with a liquid stage allowing atomic resolution imaging of nanomaterials in a colloidal suspension, core EEL spectra acquisition, continuous flow, controlled growth of nanocrystals and systematic calibration of the effect of the electron dose on silver nuclei formation.

Naval Research Laboratory Major Facilities 2008

DTIC Science & Technology

2008-10-01

Development Laboratory • Secure Supercomputing Facility • CBD/Tilghman Island IR Field Evaluation Facility • Ultra-Short-Pulse Laser Effects Research...EMI Test Facility • Proximity Operations Testbed GENERAL INFORMATION • Maps EX EC U TI V E D IR EC TO RA TE Code 1100 – Institute for Nanoscience...facility: atomic force microscope (AFM); benchtop transmission electron microscope (TEM); cascade probe station; critical point dryer ; dual beam focused

Fabrication and characterization of dendrimer-functionalized nano-hydroxyapatite and its application in dentin tubule occlusion.

PubMed

Lin, Xuandong; Xie, Fangfang; Ma, Xueling; Hao, Yuhong; Qin, Hejia; Long, Jindong

2017-06-01

The occlusion of dentinal tubules is an effective method to alleviate the symptoms of dentin hypersensitivity. In this paper, we successfully modified nano-hydroxyapatite (n-HAP) with carboxyl-terminated polyamidoamine dendrimers by an aqueous-based chemical method and verified by fourier transform infrared spectroscopy (FTIR) and transmission electron microscope (TEM). Then the demineralization dentin discs were randomly divided into 4 groups, corresponding to subsequent brushing experiments: deionized water and kept in artificial saliva (AS), dendrimer-functionalized n-HAP and stored in AS, n-HAP and saved in AS, dendrimer-functionalized n-HAP and stored in deionized water. After 7 days of simulated brushing, dentin discs followed the in vitro characterization using scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy and microhardness test. These data suggested that dendrimer-functionalized n-HAP could crosslink with collagen fibers and resulted in effective dentinal tubule occlusion. Moreover, the new material can induce the HAP formation with the help of superficial carboxyl and fill the spaces in dentinal tubules furtherly. The microhardness of dendrimer-functionalized n-HAP-treated specimens was significantly higher than others. In summary, dendrimer-functionalized n-HAP can be a new therapeutic material for the treatment of dentin hypersensitivity.

Soybean peroxidase immobilized onto silica-coated superparamagnetic iron oxide nanoparticles: Effect of silica layer on the enzymatic activity.

PubMed

Donadelli, Jorge A; García Einschlag, Fernando S; Laurenti, Enzo; Magnacca, Giuliana; Carlos, Luciano

2018-01-01

Peroxidase immobilization onto magnetic supports is considered an innovative strategy for the development of technologies that involves enzymes in wastewater treatment. In this work, magnetic biocatalysts were prepared by immobilization of soybean peroxidase (SBP) onto different silica-coated superparamagnetic iron oxide nanoparticles. The obtained magnetic biocatalysts were tested for the degradation of malachite green (MG), a pollutant often found in industrial wastewaters and with significant drawbacks for the human and environmental health. A deep physicochemical characterization of the materials was performed by means of X-ray diffraction (XRD), Fourier Transform Infrared Spectroscopy (FTIR), High Resolution-Transmission Electron Microscope (HR-TEM) and magnetization measurements among others techniques. Results showed high immobilization yield of SBP onto nanomaterials with excellent properties for magnetic recoverability. A partial loss of activity with respect to free SBP was observed, compatible with the modification of the conformational structure of the enzyme after immobilization. The structural modification depended on the amount (and thickness) of silica present in the hybrid materials and the activity yield of 43% was obtained for the best biocatalyst. Thermal stability and reusability capacity were also evaluated. Copyright © 2017 Elsevier B.V. All rights reserved.

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.

Construction of Chitosan-Zn-Based Electrochemical Biosensing Platform for Rapid and Accurate Assay of Actin.

PubMed

Sun, Chong; Zou, Ye; Wang, Daoying; Geng, Zhiming; Xu, Weimin; Liu, Fang; Cao, Jinxuan

2018-06-07

This work reports a study on the development of a sensitive immunosensor for the assay of actin, which is fabricated using sensing material chitosan-Zn nanoparticles (NPs) and anti-actin modified on glassy carbon electrode respectively. The prepared materials were characterized using transmission electron microscope (TEM), fourier transform infrared spectra (FTIR), X-ray diffraction (XRD) spectra, and circular dichroism (CD) techniques. Meanwhile, the electrochemical properties were studied by linear sweep voltammetric (LSV), electrochemical impedance spectra (EIS), and differential pulse voltammetry (DPV). According to the experiments, under the optimum conditions, the linear fitting equation was I (μA) = -17.31 + 78.97c (R² = 0.9948). The linear range was from 0.0001 to 0.1 mg/mL and the detection limit (LOD, S/N = 3) was 21.52 ng/mL. The interference studies were also performed for checking the sensors' selectivity to actin. With better properties of the chitosan-Zn NPs, the modified electrode is considered as a better candidate than Western blot or immunohistochemical method for real-time usability. The detection limit reported is the lowest till date and this method provides a new approach for quality evaluation.

Synthesis and characterization of Cu0.3Zn0.5Mg0.2Fe2O4 nanoparticles as a magnetic drug delivery system

NASA Astrophysics Data System (ADS)

Ansari, Mohammad; Bigham, Ashkan; Hassanzadeh-Tabrizi, S. A.; Abbastabar Ahangar, H.

2017-10-01

Mixed spinel ferrite nanoparticles are being applied in biomedical applications due to their biocompatibility, antibacterial activity, particular magnetic and electronic properties with chemical and thermal stabilities. The Cu0.3Zn0.5Mg0.2Fe2O4 nanoparticles are synthesized through the thermal treatment method. Polyvinyl alcohol (PVA) is used as the capping agent to stabilize the particles and prevent their agglomeration. The synthesized nanoparticles are characterized through X-ray diffractometer (XRD), Fourier transform infrared spectroscopy (FTIR), N2 adsorption-desorption, field emission scanning electron microscopy (FESEM), and transmission electron microscope (TEM). The magnetic characterization is made on a vibrating sample magnetometer (VSM), which displayed super-paramagnetic behavior of the synthesized sample. Potential application of the Cu0.3Zn0.5Mg0.2Fe2O4 nanoparticles as a drug delivery agent is assessed in vitro by estimating their release properties. The obtained results indicate that the amount of ibuprofen (IBU) adsorbed into the nanocarrier of Cu0.3Zn0.5Mg0.2Fe2O4 is 104 mg/g and the drug release is sustained up to 72 h.

Preparation and characterization of new photoluminescent nano-powder based on Eu3+:La2Ti2O7 and dispersed into silica matrix for latent fingerprint detection

NASA Astrophysics Data System (ADS)

Saif, M.; Alsayed, N.; Mbarek, A.; El-Kemary, M.; Abdel-Mottaleb, M. S. A.

2016-12-01

Pure lanthanum titanate doped with europium metal ions (La2Ti2O7:Eu3+) and dispersed in silica matrix phosphor powder was prepared by sol-gel process followed by thermal treatment. The prepared nanophosphors were characterized by powder X-ray Diffraction (XRD), Fourier Transform Infrared (FT-IR), Transmission Electron Microscope (TEM), Energy Dispersive Spectroscopy (EDX), and Photoluminescence Spectroscopy (PL). The effects of silica, thermal treatment, Eu3+ ion, and surfactant (CTAB) concentrations on the crystal, morphology, and photoluminescence properties were investigated. The present work found that dispersion of La2Ti2O7:Eu3+ into silica matrix significantly altered the morphology of La2Ti2O7:Eu3+ from high crystalline micro-plate like shape into amorphous aggregated Nano-spherical shape. The high separated spherical shape with intense red PL emission and long lifetime was obtained from 10 mol% Eu3+:La2Ti2O7:Eu3+, dispersed into silica matrix, and prepared in the presence of CTAB. The high PL Nano-phosphor has been successfully used in developing latent fingerprint from various forensic relevant materials.

Effective degradation of rhodamine B by electro-Fenton process, using ferromagnetic nanoparticles loaded on modified graphite felt electrode as reusable catalyst: in neutral pH condition and without external aeration.

PubMed

Tian, Jiangnan; Zhao, Jixiang; Olajuyin, Ayobami Matthew; Sharshar, Moustafa Mohamed; Mu, Tingzhen; Yang, Maohua; Xing, Jianmin

2016-08-01

Polytetrafluoroethylene/ferromagnetic nanoparticle/carbon black (PTFE/MNP/CB)-modified graphite felt (GF) was successfully applied as cathode for the mineralization of rhodamine B (RhB) in electro-Fenton (EF) process. The modified cathode showed high decolorization efficiency for RhB solution even in neutral pH condition and without external aeration, achieving nearly complete decolorization and 89.52 % total organic carbon (TOC) removal after 270-min oxidation with the MNP load 1.2 g at 50 A/m(2). Moreover, the operational parameters (current density, MNP load, initial pH, and airflow rate) were optimized. After that, adsorption isotherm was also conducted to compare the absorption quantity of CB and carbon nanotube (CNT). Then, the surface morphologies of MNPs were characterized by transmission electron microscope (TEM), energy-dispersive X-ray detector (EDX), and Fourier transform infrared spectroscopy (FTIR); and the modified cathode was characterized by SEM and contact angle. Finally, the stability and reusability of modified cathode were tested. Result uncovered that the PTFE/MNP/CB-modified cathode has the potential for industrial application and the solution after treatment was easily biodegradable.

A novel application of carbon dots for colorimetric determination of fenitrothion insecticide based on the microextraction method

NASA Astrophysics Data System (ADS)

Larki, A.

2017-02-01

In this work, the intrinsic colorimetric property of carbon dots (CDs) was utilized for the determination of fenitrothion by applying dispersive liquid-liquid microextraction (DLLME) method. Label free CDs are extracted into carbon tetrachloride via assistance of trioctylmethylammonium chloride (Aliquat 336), which also acts as a disperser agent in this technique. The enriched CDs show an absorption signal at 365 nm, which increases in the presence of fenitrothion. The absorbance increase of CDs in organic phase was used as an analytical signal for the determination of fenitrothion. The synthesized CDs were characterized by UV-visible, fluorescence, Fourier transform infrared (FT-IR) and transmission electron microscopic (TEM). Under the optimized conditions, beer's law was obeyed in the range of 1.0-250.0 ng mL- 1 of fenitrothion with the limit of detection for fenitrothion was 0.2 ng mL- 1. The relative standard deviation for eight replicate measurements of fenitrothion at concentrations of 25 and 100 ng mL- 1 were calculated to be 1.5 and 3.7%, respectively. The proposed method was successfully applied in the determination of fenitrothion in water samples with satisfactory results.

Effect of SiO2 grafted MWCNTs on the mechanical and dielectric properties of PEN composite films

NASA Astrophysics Data System (ADS)

Jin, Fei; Feng, Mengna; Huang, Xu; Long, Cheng; Jia, Kun; Liu, Xiaobo

2015-12-01

In this study, the functional poly (arylene ether nitrile) (PEN)/multiwall carbon nanotubes (MWCNTs)/SiO2 nanocomposite with high mechanical and good electrical properties were fabricated through a simple and effective method. Specifically, the surface modification using highly ordered and porous SiO2 not only improves the dispersion of the MWCNTs in polymer matrix, but also combines the excellent properties of SiO2 and MWCNTs. Transmission electron microscopy (TEM), Fourier transform infrared spectra (FTIR), and scanning electron microscope (SEM) were employed to confirm the surface functionalization of MWCNTs. As a result, all the composite films exhibited good dielectric properties with high dielectric constant of 7 as well as low dielectric loss of 0.04. Besides, the results of mechanical tests showed that the tensile strength and modulus reached their highest values at the 2 wt% MWCNTs-SiO2 loading content (125 MPa and 2950 MPa, respectively). The rheological results showed that MWCNTs-SiO2/PEN composites have a typical solid-like viscoelastic response as frequencies changes. Therefore, all the results revealed that surface functionalization has strong influence on the dispersion state of MWCNTs in PEN matrix.

TiO2 nanoparticles versus TiO2-SiO2 nanocomposites: a comparative study of photo catalysis on acid red 88.

PubMed

Balachandran, K; Venckatesh, Rajendran; Sivaraj, Rajeshwari; Rajiv, P

2014-07-15

A novel, simple, less time-consuming and cost-effective wet chemical technique was used to synthesis TiO2 nanoparticles and TiO2-SiO2 nanocomposites using Titanium tetra isopropoxide (TTIP) as a precursor relatively at low temperature in acidic pH. Titania sol was prepared by hydrolysis of TTIP and was mixed with silicic acid and tetrahydrofuran mixture. The reaction was carried out under vigorous stirring for 6h and dried at room temperature. The resulting powders were characterized by UV-Visible spectroscopy, Fourier transform infrared (FT-IR), X-ray diffraction, scanning electron microscope (SEM) and transmission electron microscope (TEM). The grain size of the particles was calculated by X-ray diffraction, surface morphology and chemical composition was determined from scanning electron microscopy-energy dispersive spectroscopy, metal oxide stretching was confirmed from FT-IR spectroscopy, band gap was calculated using UV-Visible spectroscopy. Surface area of the composite as calculated by BET analyzer and it was found to be 65 and 75 m(2)/g for TiO2 and TiO2-SiO2 respectively. The photocatalytic experiments were performed with aqueous solution of acid red 88 with TiO2 and TiO2-SiO2 batch studies for 4h irradiation, direct photolysis of TiO2 and TiO2-SiO2 contributed 94.2% and 96.5% decomposition in solar radiation for the optimized concentration of acid red 88. Copyright © 2014 Elsevier B.V. All rights reserved.

Fabrication, characterization and gamma rays shielding properties of nano and micro lead oxide-dispersed-high density polyethylene composites

NASA Astrophysics Data System (ADS)

Mahmoud, Mohamed E.; El-Khatib, Ahmed M.; Badawi, Mohamed S.; Rashad, Amal R.; El-Sharkawy, Rehab M.; Thabet, Abouzeid A.

2018-04-01

Polymer composites of high-density polyethylene (HD-PE) filled with powdered lead oxide nanoparticles (PbO NPs) and bulk lead oxide (PbO Blk) were prepared with filler weight fraction [10% and 50%]. These polymer composites were investigated for radiation-shielding of gamma-rays emitted from radioactive point sources [241Am, 133Ba, 137Cs, and 60Co]. The polymer was found to decrease the heaviness of the shielding material and increase the flexibility while the metal oxide fillers acted as principle radiation attenuators in the polymer composite. The prepared composites were characterized by Fourier transform infrared spectrophotometer (FT-IR), X-ray diffraction (XRD), thermogravimetric analysis (TGA), scanning electron microscope (SEM), Brunauer-Emmett-Teller surface area (BET) and field emission transmission electron microscope (FE-TEM). The morphological analysis of the assembled composites showed that, PbO NPs and PbO Blk materials exhibited homogenous dispersion in the polymer-matrix. Thermogravimetric analysis (TGA) demonstrated that the thermal-stability of HD-PE was enhanced in the presence of both PbO Blk and PbO NPs. The results declared that, the density of polymer composites was increase with the percentage of filler contents. The highest density value was identified as 1.652 g cm-3 for 50 wt% of PbO NPs. Linear attenuation coefficients (μ) have been estimated from the use of XCOM code and measured results. Reasonable agreement was attended between theoretical and experimental results. These composites were also found to display excellent percentage of heaviness with respect to other conventional materials.

Ammonium nitrogen removal from coking wastewater by chemical precipitation recycle technology.

PubMed

Zhang, Tao; Ding, Lili; Ren, Hongqiang; Xiong, Xiang

2009-12-01

Ammonium nitrogen removal from wastewater has been of considerable concern for several decades. In the present research, we examined chemical precipitation recycle technology (CPRT) for ammonium nitrogen removal from coking wastewater. The pyrolysate resulting from magnesium ammonium phosphate (MAP) pyrogenation in sodium hydroxide (NaOH) solution was recycled for ammonium nitrogen removal from coking wastewater. The objective of this study was to investigate the conditions for MAP pyrogenation and to characterize of MAP pyrolysate for its feasibility in recycling. Furthermore, MAP pyrolysate was characterized by scanning electron microscope (FESEM), transmission electron microscope (TEM), Fourier transform infrared spectroscopy (FTIR) as well as X-ray diffraction (XRD). The MAP pyrolysate could be produced at the optimal condition of a hydroxyl (OH(-)) to ammonium molar ratio of 2:1, a heating temperature of 110 degrees C, and a heating time of 3h. Surface characterization analysis indicated that the main component of the pyrolysate was amorphous magnesium sodium phosphate (MgNaPO(4)). The pyrolysate could be recycled as a magnesium and phosphate source at an optimum pH of 9.5. When the recycle times were increased, the ammonium nitrogen removal ratio gradually decreased if the pyrolysate was used without supplementation. When the recycle times were increased, the ammonium nitrogen removal efficiency was not decreased if the added pyrolysate was supplemented with MgCl(2).6H(2)O plus Na(2)HPO(4).12H(2)O during treatment. A high ammonium nitrogen removal ratio was obtained by using pre-formed MAP as seeding material.

Detecting single-electron events in TEM using low-cost electronics and a silicon strip sensor.

PubMed

Gontard, Lionel C; Moldovan, Grigore; Carmona-Galán, Ricardo; Lin, Chao; Kirkland, Angus I

2014-04-01

There is great interest in developing novel position-sensitive direct detectors for transmission electron microscopy (TEM) that do not rely in the conversion of electrons into photons. Direct imaging improves contrast and efficiency and allows the operation of the microscope at lower energies and at lower doses without loss in resolution, which is especially important for studying soft materials and biological samples. We investigate the feasibility of employing a silicon strip detector as an imaging detector for TEM. This device, routinely used in high-energy particle physics, can detect small variations in electric current associated with the impact of a single charged particle. The main advantages of using this type of sensor for direct imaging in TEM are its intrinsic radiation hardness and large detection area. Here, we detail design, simulation, fabrication and tests in a TEM of the front-end electronics developed using low-cost discrete components and discuss the limitations and applications of this technology for TEM.

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

Kawasaki, Tadahiro; PRESTO-JST, 4-1-8 Honcho, Kawaguchi, Saitama 332-0012; Ueda, Kouta

We have developed an improved, windowed type environmental-cell (E-cell) transmission electron microscope (TEM) for in situ observation of gas-solid interactions, such as catalytic reactions at atmospheric pressure. Our E-cell TEM includes a compact E-cell specimen holder with mechanical stability, resulting in smoother introduction of the desired gases compared with previous E-cell TEMs. In addition, the gas control unit was simplified by omitting the pressure control function of the TEM pre-evacuation chamber. This simplification was due to the successful development of remarkably tough thin carbon films as the window material. These films, with a thickness of <10 nm, were found tomore » withstand pressure differences >2 atm. Appropriate arrangement of the specimen position inside the E-cell provided quantitatively analyzable TEM images, with no disturbances caused by the windowed films. As an application, we used this E-cell TEM to observe the dynamic shape change in a catalytic gold nanoparticle supported on TiO{sub 2} during the oxidation of CO gas.« less

Miscibility and thermal behavior of poly (ε-caprolactone)/long-chain ester of cellulose blends

Treesearch

Yuzhi Xu; Chunpeng Wang; Nicole M. Stark; Zhiyong Cai; Fuxiang Chu

2012-01-01

The long-chain cellulose ester (LCCE) cellulose laurate, poly(ε-caprolactone) (PCL) and their blends were characterized by tensile strength, Fourier transform infrared spectroscopy (FTIR), dynamic mechanical thermal analysis, thermogravimetric analysis (TGA), and transmission electron microscopy (TEM). The compatibility of the blends was...

Preparation and characterization of novel polyimide/functionalized ZnO bionanocomposite for gas separation and study of their antibacterial activity

NASA Astrophysics Data System (ADS)

Esmaielzadeh, Sheida; Ahmadizadegan, Hashem

2018-04-01

In the present investigation novel Polyimide/functionalized ZnO (PI/ZnO) bionanocomposites containing amino acid (Methionine) and benzimidazole pendent groups with different amounts of modified ZnO nanoparticles (ZnO NPs) were successfully prepared through ultrasonic irradiation technique. Due to the high surface energy and tendency for agglomeration, the surface ZnO NPs was modified by a coupling agent as 3- methacryloxypropyl-trimethoxysilane (MPS) to form MPS-ZnO nanoparticles. The ultrasonic irradiation effectively changes the rheology and the glass transition temperature and the crystallinity of the composite polymer. PI/ZnO nanocomposites were characterized by Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), scanning electron microscopy (SEM) and transmission electron microscope (TEM). TEM analysis showed that the modified ZnO nanoparticles were homogeneously dispersed in polymer matrix. The TGA results of PI/ZnO nanocomposites showed that the thermal stability is obviously improved the presence of MPS-ZnO NPs in comparison with the pure PI and that this increase is higher when the NP content increases. The permeabilities of pure H2, CH4, O2, and N2 gases through prepared membranes were determined at room temperature (25 °C) and 20 bar feed pressure. The membranes having 20% ZnO showed higher values of H2 permeability, and H2/CH4 and H2/N2 ideal selectivities (the ratio of pair gas permeabilities) compared with other membranes. The antibacterial activity of bionanocomposite films was tested against gram-positive bacteria (Staphylococcus aureus and Bacillus subtilis) and gram-negative bacteria (Escherichia coli and Pseudomonas aeruginosa). Further, it was observed that antibacterial activity of the resulting hybrid biofilms showed somewhat higher for gram-positive bacteria compared to gram-negative bacteria.

Collisional Histories of Comets and Trojan Asteroids: Diopside, Magnesite, and Fayalite Impact Studies

NASA Technical Reports Server (NTRS)

Lederer, S. M.; Jensen, E. A.; Wooden, D. H.; Lindsay, S. S.; Nakamura-Messenger, K.; Smith, D. C.; Keller, L. P.; Cintala, M. J.; Zolensky, M. E.

2012-01-01

Comets and asteroids have weathered dynamic histories, as evidenced by their rough surfaces. The Nice model describes a violent reshuffling of small bodies during the Late Heavy Bombardment, with collisions acting to grind these planetesimals away. This creates an additional source of impact material that can re-work the surfaces of the larger bodies over the lifetime of the solar system. Here, we investigate the possibility that signatures due to impacts (e.g. from micrometeoroids or meteoroids) could be detected in their spectra, and how that can be explained by the physical manifestation of shock in the crystalline structure of minerals. All impact experiments were conducted in the Johnson Space Center Experimental Impact Laboratory using the vertical gun. Impact speeds ranged from approx.2.0 km/s to approx.2.8 km/s. All experiments were conducted at room temperature. Minerals found in comets and asteroids were chosen as targets, including diopside (MgCaSi2O6, monoclinic pyroxene), magnesite (MgCO3, carbonate), and fayalite (FeSiO4, olivine). Impacted samples were analyzed using a Fourier Transform Infrared Spectrometer (FTIR) and a Transmission Electron Microscope (TEM). Absorbance features in the 8-13 m spectral region demonstrate relative amplitude changes as well as wavelength shifts. Corresponding TEM images exhibit planar shock dislocations in the crystalline structure, attributed to deformation at high strain and low temperatures. Elongating or shortening the axes of the crystalline structure of forsterite (Mg2SiO4, olivine) using a discrete dipole approximation model (Lindsay et al., submitted) yields changes in spectral features similar to those observed in our impacted laboratory minerals.

A Fourier collocation time domain method for numerically solving Maxwell's equations

NASA Technical Reports Server (NTRS)

Shebalin, John V.

1991-01-01

A new method for solving Maxwell's equations in the time domain for arbitrary values of permittivity, conductivity, and permeability is presented. Spatial derivatives are found by a Fourier transform method and time integration is performed using a second order, semi-implicit procedure. Electric and magnetic fields are collocated on the same grid points, rather than on interleaved points, as in the Finite Difference Time Domain (FDTD) method. Numerical results are presented for the propagation of a 2-D Transverse Electromagnetic (TEM) mode out of a parallel plate waveguide and into a dielectric and conducting medium.

A simple way to obtain backscattered electron images in a scanning transmission electron microscope.

PubMed

Tsuruta, Hiroki; Tanaka, Shigeyasu; Tanji, Takayoshi; Morita, Chiaki

2014-08-01

We have fabricated a simple detector for backscattered electrons (BSEs) and incorporated the detector into a scanning transmission electron microscope (STEM) sample holder. Our detector was made from a 4-mm(2) Si chip. The fabrication procedure was easy, and similar to a standard transmission electron microscopy (TEM) sample thinning process based on ion milling. A TEM grid containing particle objects was fixed to the detector with a silver paste. Observations were carried out using samples of Au and latex particles at 75 and 200 kV. Such a detector provides an easy way to obtain BSE images in an STEM. © The Author 2014. Published by Oxford University Press on behalf of The Japanese Society of Microscopy. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

Preparation and Loading Process of Single Crystalline Samples into a Gas Environmental Cell Holder for In Situ Atomic Resolution Scanning Transmission Electron Microscopic Observation.

PubMed

Straubinger, Rainer; Beyer, Andreas; Volz, Kerstin

2016-06-01

A reproducible way to transfer a single crystalline sample into a gas environmental cell holder for in situ transmission electron microscopic (TEM) analysis is shown in this study. As in situ holders have only single-tilt capability, it is necessary to prepare the sample precisely along a specific zone axis. This can be achieved by a very accurate focused ion beam lift-out preparation. We show a step-by-step procedure to prepare the sample and transfer it into the gas environmental cell. The sample material is a GaP/Ga(NAsP)/GaP multi-quantum well structure on Si. Scanning TEM observations prove that it is possible to achieve atomic resolution at very high temperatures in a nitrogen environment of 100,000 Pa.

Metal dusting behavior of 321 stainless steel: Effects of edge and corner

NASA Astrophysics Data System (ADS)

Chang, Chia-Hao; Tsai, Wen-Ta

2011-04-01

The metal dusting behavior of 321 stainless steel (SS) in a flowing mixed CO/H2/H2O gas stream at 600 °C for 500 h and 1000 h was investigated. The microstructures and chemical compositions of the reaction products at the surface and those in the substrate under the pits were examined by using a scanning electron microscope (SEM) and a transmission electron microscope (TEM), each combined with an energy dispersive spectrometer (EDS). The phenomenon of a pitting attack that occurred preferentially at the edges and corners of the specimens was the focus of this study. The carburization behavior in the steel substrate under the pits was also characterized. Matrix carbide in the form of Cr7C3 and grain boundary carbide in the form of Cr23C6 were identified by TEM.

Optical Scatter Imaging with a digital micromirror device.

PubMed

Zheng, Jing-Yi; Pasternack, Robert M; Boustany, Nada N

2009-10-26

We had developed Optical Scatter Imaging (OSI) as a method which combines light scattering spectroscopy with microscopic imaging to probe local particle size in situ. Using a variable diameter iris as a Fourier spatial filter, the technique consisted of collecting images that encoded the intensity ratio of wide-to-narrow angle scatter at each pixel in the full field of view. In this paper, we replace the variable diameter Fourier filter with a digital micromirror device (DMD) to extend our assessment of morphology to the characterization of particle shape and orientation. We describe our setup in detail and demonstrate how to eliminate aberrations associated with the placement of the DMD in a conjugate Fourier plane of our microscopic imaging system. Using bacteria and polystyrene spheres, we show how this system can be used to assess particle aspect ratio even when imaged at low resolution. We also show the feasibility of detecting alterations in organelle aspect ratio in situ within living cells. This improved OSI system could be further developed to automate morphological quantification and sorting of non-spherical particles in situ.

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

Buck, E.C.; Dietz, N.L.; Bates, J.K.

Uranium contaminated soils from the Fernald Operation Site, Ohio, have been examined by a combination of optical microscopy, scanning electron microscopy with backscattered electron detection (SEM/BSE), and analytical electron microscopy (AEM). A method is described for preparing of transmission electron microscopy (TEM) thin sections by ultramicrotomy. By using these thin sections, SEM and TEM images can be compared directly. Uranium was found in iron oxides, silicates (soddyite), phosphates (autunites), and fluorite. Little uranium was associated with clays. The distribution of uranium phases was found to be inhomogeneous at the microscopic level.

Direct Observation Through In Situ Transmission Electron Microscope of Early States of Crystallization in Nanoscale Metallic Glasses

NASA Astrophysics Data System (ADS)

Xie, Y.; Sohn, S.; Schroers, J.; Cha, J. J.

2017-11-01

Crystallization is a complex process that involves multiscale physics such as diffusion of atomic species over multiple length scales, thermodynamic energy considerations, and multiple possible intermediate states. In situ crystallization experiments inside a transmission electron microscope (TEM) using nanostructured metallic glasses (MGs) provide a unique platform to study directly crystallization kinetics and pathways. Here, we study the embryonic state of eutectic growth using Pt-Ni-Cu-P MG nanorods under in situ TEM. We directly observe the nucleation and growth of a Ni-rich polymorphic phase, followed by the nucleation and slower growth of a Cu-rich phase. The suppressed growth kinetics of the Cu-rich phase is attributed to locally changing chemical compositions. In addition, we show that growth can be controlled by incorporation of an entire nucleus instead of individual atoms. Such a nucleus has to align with the crystallographic orientation of a larger grain before it can be incorporated into the crystal. By directly observing the crystallization processes, particularly the early stages of non-polymorphic growth, in situ TEM crystallization studies of MG nanostructures provide a wealth of information, some of which can be applied to typical bulk crystallization.

EBSD and TEM characterization of high burn-up mixed oxide fuel

NASA Astrophysics Data System (ADS)

Teague, Melissa; Gorman, Brian; Miller, Brandon; King, Jeffrey

2014-01-01

Understanding and studying the irradiation behavior of high burn-up oxide fuel is critical to licensing of future fast breeder reactors. Advancements in experimental techniques and equipment are allowing for new insights into previously irradiated samples. In this work dual column focused ion beam (FIB)/scanning electron microscope (SEM) was utilized to prepared transmission electron microscope samples from mixed oxide fuel with a burn-up of 6.7% FIMA. Utilizing the FIB/SEM for preparation resulted in samples with a dose rate of <0.5 mRem/h compared to ∼1.1 R/h for a traditionally prepared TEM sample. The TEM analysis showed that the sample taken from the cooler rim region of the fuel pellet had ∼2.5× higher dislocation density than that of the sample taken from the mid-radius due to the lower irradiation temperature of the rim. The dual column FIB/SEM was additionally used to prepared and serially slice ∼25 μm cubes. High quality electron back scatter diffraction (EBSD) were collected from the face at each step, showing, for the first time, the ability to obtain EBSD data from high activity irradiated fuel.

Radiation sensitivity of quartz crystal oscillators experiment for the Long Duration Exposure Facility (LDEF)

NASA Technical Reports Server (NTRS)

Ahearn, J. S.; Venables, J. D.

1992-01-01

Factors determining the radiation sensitivity of quartz crystal oscillators were studied on NASA's LDEF. Quartz materials were examined in the transmission electron microscope (TEM) and classified as to their sensitivity to radiation damage by establishing the rate of damage caused by the electron beam in the microscope. Two types of materials, i.e., swept premium Q quartz and natural quartz were chosen because clear differences were observed in their response to the electron beam in the TEM studies. Quartz resonators were then fabricated from them, tested for frequency stability over a greater than 6 mo. period and flown on the LDEF satellite. After retrieval (more than 7 yrs in space) the stability of the resonators was again determined. All of the space exposed resonators fabricated with swept premium Q material exhibited a frequency shift above that of the control resonators: none of the resonators fabricated from the natural quartz materials exhibited such a shift. The significant differences observed between the two types of materials in both the ground-based TEM studies and the space radiation induced frequency changes suggest that there may be a correlation between the two observations.

EBSD and TEM Characterization of High Burn-up Mixed Oxide Fuel

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

Teague, Melissa C.; Gorman, Brian P.; Miller, Brandon D.

2014-01-01

Understanding and studying the irradiation behavior of high burn-up oxide fuel is critical to licensing of future fast breeder reactors. Advancements in experimental techniques and equipment are allowing for new insights into previously irradiated samples. In this work dual column focused ion beam (FIB)/scanning electron microscope (SEM) was utilized to prepared transmission electron microscope samples from mixed oxide fuel with a burn-up of 6.7% FIMA. Utilizing the FIB/SEM for preparation resulted in samples with a dose rate of <0.5 mRem/h compared to approximately 1.1 R/h for a traditionally prepared TEM sample. The TEM analysis showed that the sample taken frommore » the cooler rim region of the fuel pellet had approximately 2.5x higher dislocation density than that of the sample taken from the mid-radius due to the lower irradiation temperature of the rim. The dual column FIB/SEM was additionally used to prepared and serially slice approximately 25 um cubes. High quality electron back scatter diffraction (EBSD) were collected from the face at each step, showing, for the first time, the ability to obtain EBSD data from high activity irradiated fuel.« less

A Structural Study of Escherichia coli Cells Using an In Situ Liquid Chamber TEM Technology.

PubMed

Wang, Yibing; Chen, Xin; Cao, Hongliang; Deng, Chao; Cao, Xiaodan; Wang, Ping

2015-01-01

Studying cell microstructures and their behaviors under living conditions has been a challenging subject in microbiology. In this work, in situ liquid chamber TEM was used to study structures of Escherichia coli cells in aqueous solutions at a nanometer-scale resolution. Most of the cells remained intact under electron beam irradiation, and nanoscale structures were observed during the TEM imaging. The analysis revealed structures of pili surrounding the E. coli cells; the movements of the pili in the liquid were also observed during the in situ tests. This technology also allowed the observation of features of the nucleoid in the E. coli cells. Overall, in situ TEM can be applied as a valuable tool to study real-time microscopic structures and processes in microbial cells residing in native aqueous solutions.

Heterodyne Interferometry with a Scanning Optical Microscope.

NASA Astrophysics Data System (ADS)

Hobbs, Philip Charles Danby

The design and implementation of a confocal optical microscope which functions as an electronically scanned heterodyne interferometer are described. Theoretical models based on Fourier optics for general samples and on exact series solution of the scalar Helmholtz equation for a class of trench structures are developed and compared with experimental data. Good agreement is obtained. The associated data acquisition system, also described, enables the system to measure both the amplitude (to 12 bits) and the phase (to 0.1^circ) of a returned optical beam, at a continuous rate of 30,000 points per second. The microscope system uses a wide-band tellurium dioxide acousto-optic cell for electronic scanning, frequency shifting, and beam splitting/combining. It uses a stationary reference beam on the sample for vibration cancellation, which results in a system of great vibration immunity. It can measure relief ranging from a few tenths of a micron down to a few Angstroms, and line widths down to well below 0.4 micron, using light of 0.5 micron wavelength. Angstrom resolution can be achieved in a single full-speed scan, without special vibration isolation equipment, providing that folding mirrors are avoided. A signal processing algorithm based on Fourier deconvolution is presented; it takes advantage of the extra bandwidth of a confocal system and the availability of both amplitude and phase, to improve the lateral resolution by approximately a factor of two. Experimental results are shown, which demonstrate phase edge resolution (10%-90%) of 0.45 lambda (raw data), and 0.18 lambda (after filtering), in excellent agreement with the Fourier optics prediction. The exact scalar theory calculates the response of the microscope as it scans over an infinitely long rectangular trench in a plane boundary on which Dirichlet boundary conditions apply. An expansion in cavity modes inside the trench is used to match the field and its derivatives across the mouth of the trench to get the self-consistent solution. A listing is appended of a program for an HP personal computer which performs the simulation in 1 to 5 minutes' running time for most cases. The trench theory is compared with the Fourier theory and with experimental results for actual metal trenches, with good results.

Room temperature chemical synthesis of lead selenide thin films with preferred orientation

NASA Astrophysics Data System (ADS)

Kale, R. B.; Sartale, S. D.; Ganesan, V.; Lokhande, C. D.; Lin, Yi-Feng; Lu, Shih-Yuan

2006-11-01

Room temperature chemical synthesis of PbSe thin films was carried out from aqueous ammoniacal solution using Pb(CH3COO)2 as Pb2+ and Na2SeSO3 as Se2- ion sources. The films were characterized by a various techniques including, X-ray diffraction (XRD), energy dispersive X-ray analysis (EDAX), scanning electron microscopy (SEM), transmission electron microscopy (TEM), high resolution transmission electron microscopy (HR-TEM), selected area electron diffraction (SAED), Fast Fourier transform (FFT) and UV-vis-NIR techniques. The study revealed that the PbSe thin film consists of preferentially oriented nanocubes with energy band gap of 0.5 eV.

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

Janeoo, Shashi; Sharma, Mamta, E-mail: mamta.phy85@gmail.com; Goswamy, J.

Polyaniline-indium oxide (In{sub 2}O{sub 3}/PANI) nanocomposite have been prepared by in-situ polymerization of aniline and as-synthesized In{sub 2}O{sub 3} nanoparticles. X-ray diffraction (XRD), Transmission electron microscopy (TEM), Fourier transformation infrared (FTIR) and UV/Vis spectroscopy techniques are used to investigate the structural and optical properties of In{sub 2}O{sub 3}/PANI nanocomposite. TEM analysis shows In{sub 2}O{sub 3} nanoparticles are embedded in PANI nanofibers. FTIR spectra show the good interactions between PANI nanofibers and In{sub 2}O{sub 3} nanoparticles. The band gap and electronic transitions in In{sub 2}O{sub 3}/PANI nanocomposite is determined by using UV/Vis spectra.

Fabrication and In Situ Transmission Electron Microscope Characterization of Free-Standing Graphene Nanoribbon Devices.

PubMed

Wang, Qing; Kitaura, Ryo; Suzuki, Shoji; Miyauchi, Yuhei; Matsuda, Kazunari; Yamamoto, Yuta; Arai, Shigeo; Shinohara, Hisanori

2016-01-26

Edge-dependent electronic properties of graphene nanoribbons (GNRs) have attracted intense interests. To fully understand the electronic properties of GNRs, the combination of precise structural characterization and electronic property measurement is essential. For this purpose, two experimental techniques using free-standing GNR devices have been developed, which leads to the simultaneous characterization of electronic properties and structures of GNRs. Free-standing graphene has been sculpted by a focused electron beam in transmission electron microscope (TEM) and then purified and narrowed by Joule heating down to several nanometer width. Structure-dependent electronic properties are observed in TEM, and significant increase in sheet resistance and semiconducting behavior become more salient as the width of GNR decreases. The narrowest GNR width we obtained with the present method is about 1.6 nm with a large transport gap of 400 meV.

Novel perovskite coating of strontium zirconate in Inconel substrate

NASA Astrophysics Data System (ADS)

Venkatesh, G.; Blessto, B.; Rao, C. Santhosh Kumar; Subramanian, R.; Berchmans, L. John

2018-02-01

Thermal Barrier Coatings (TBC) provides a low thermal conductivity barrier to heat transfer from the hot gas in the engine to the surface of the coated alloy component. SrZrO3 powder are prepared by Sol Gel synthesis method. The synthesized powder sample is characterized by X Ray Diffraction Technique (XRD), Scanning Electron Microscope (SEM) and Transmission Electron Microscope (TEM) and the results are interpreted. The Polycrystalline nature of SrZrO3 is confirmed and lattice spacing are determined in XRD. SEM shows sub-micron sized particles and a fringed pattern is observed in TEM. The IN718 specimen is Wire Cut and Sand Blasted. A SrZrO3 double layer is coated over the Inconel specimen through a Bond Coat made of NiCoCrAlY by Plasma spraying Process and also characterized. SEM analysis of the Coating shows diffusion of Fe, Sr into the substrate.

Synthesis and characterization of silver-copper core-shell nanoparticles using polyol method for antimicrobial agent

NASA Astrophysics Data System (ADS)

Hikmah, N.; Idrus, N. F.; Jai, J.; Hadi, A.

2016-06-01

Silver and copper nanoparticles are well-known as the good antimicrobial agent. The nano-size of particles influences in enhancing the antimicrobial activity. This paper discusses the effect of molarity on the microstructure and morphology of silver-copper core-shell nanoparticles prepared by a polyol method. In this study, silver-copper nanoparticles are synthesized through the green approach of polyol method using ethylene glycol (EG) as green solvent and reductant, and polyoxyethylene-(80)-sorbitan monooleate (Tween 80) as a nontoxic stabilizer. The phase and morphology of silver-copper nanoparticles are characterized by X-ray diffraction (XRD) and Field emission scanning electron microscope (FESEM) and Transmission electron microscope (TEM). The results XRD confirm the pure crystalline of silver and copper nanoparticles with face-centered cubic (FCC) structure. FESEM and TEM analysis confirm the existence of Ag and Cu nanoparticles in core-shell shape.

New innovations for contrast enhancement in electron microscopy

NASA Astrophysics Data System (ADS)

Mohan, A.

In this study two techniques for producing and improving contrast in Electron Microscopy are discussed. The first technique deals with the production of secondary contrast in a Variable Pressure SEM under poor vacuum conditions using the specimen current signal. A review of the prior work in this field shows that the presence of the gas ions in the microscope column results in the amplification of the specimen current signal which is enriched in secondary content. The focus of this study is to establish practical conditions for imaging samples in the microscope using specimen current with gas amplification. This is done by understanding the different variables in the microscope which affect the image formation process and then finding out optimum conditions for obtaining the best possible image, i.e., the image most enhanced in secondary contrast. A few 'real life' samples analyzed using this technique show that the gas amplified specimen current images contain secondary information and, in some cases, provide clear advantages to imaging with conventional secondary and backscattered detectors. The second technique dealing with the production of phase contrast in the TEM for extremely thin, electron transparent samples, is analyzed. A review of the literature regarding prior work in the field shows that, while the theoretical aspects of production of phase contrast in the TEM using a phase plate are well understood, there have been problems in practically implementing this in the microscope. One major assumption with most of the studies is that a fiber, partially coated with gold, results in the formation of point charges which is an essential requirement for symmetrically shifting the phase of the electron beam. The focus of this portion of the dissertation is to image the type of fields associated with such a phase plate using the technique of electron holography. It is found that there are two types of fields associated with a phase plate of this sort. One is a cylindrical field which extends along the length of the fiber while the other is a localized spherically symmetric field. A series of simulations show that the spherical field can produce phase contrast in the TEM and also improve the contrast transfer properties of the microscope.

Phase Imaging: A Compressive Sensing Approach

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

Schneider, Sebastian; Stevens, Andrew; Browning, Nigel D.

Since Wolfgang Pauli posed the question in 1933, whether the probability densities |Ψ(r)|² (real-space image) and |Ψ(q)|² (reciprocal space image) uniquely determine the wave function Ψ(r) [1], the so called Pauli Problem sparked numerous methods in all fields of microscopy [2, 3]. Reconstructing the complete wave function Ψ(r) = a(r)e-iφ(r) with the amplitude a(r) and the phase φ(r) from the recorded intensity enables the possibility to directly study the electric and magnetic properties of the sample through the phase. In transmission electron microscopy (TEM), electron holography is by far the most established method for phase reconstruction [4]. Requiring a highmore » stability of the microscope, next to the installation of a biprism in the TEM, holography cannot be applied to any microscope straightforwardly. Recently, a phase retrieval approach was proposed using conventional TEM electron diffractive imaging (EDI). Using the SAD aperture as reciprocal-space constraint, a localized sample structure can be reconstructed from its diffraction pattern and a real-space image using the hybrid input-output algorithm [5]. We present an alternative approach using compressive phase-retrieval [6]. Our approach does not require a real-space image. Instead, random complimentary pairs of checkerboard masks are cut into a 200 nm Pt foil covering a conventional TEM aperture (cf. Figure 1). Used as SAD aperture, subsequently diffraction patterns are recorded from the same sample area. Hereby every mask blocks different parts of gold particles on a carbon support (cf. Figure 2). The compressive sensing problem has the following formulation. First, we note that the complex-valued reciprocal-space wave-function is the Fourier transform of the (also complex-valued) real-space wave-function, Ψ(q) = F[Ψ(r)], and subsequently the diffraction pattern image is given by |Ψ(q)|2 = |F[Ψ(r)]|2. We want to find Ψ(r) given a few differently coded diffraction pattern measurements yn = |F[HnΨ(r)]|2, where the matrices Hn encode the mask structure of the aperture. This is a nonlinear inverse problem, but has been shown to be solvable even in the underdetermined case [6]. Since each diffraction pattern yn contains diffraction information from selected regions of the same sample, the differences in each pattern contain local phase information, which can be combined to form a full estimate of the real-space wave-function[7]. References: [1] W. Pauli in “Die allgemeinen Prinzipien der Wellenmechanik“, ed. H Geiger and W Scheel, (Julius Springer, Berlin). [2] A. Tonomura, Rev. Mod. Phys. 59 (1987), p. 639. [3] J. Miao et al, Nature 400 (1999), p. 342. [4] H. Lichte et al, Annu. Rev. Mater. Res. 37 (2007), p. 539. [5] J. Yamasaki et al, Appl. Phys. Lett. 101 (2012), 234105. [6] P Schniter and S Rangan. Signal Proc., IEEE Trans. on. 64(4), (2015), pp. 1043. [7] Supported by the Chemical Imaging, Signature Discovery, and Analytics in Motion initiatives at PNNL. PNNL is operated by Battelle Memorial Inst. for the US DOE; contract DE-AC05-76RL01830.« less

Fourier transform infrared spectroscopy microscopic imaging classification based on spatial-spectral features

NASA Astrophysics Data System (ADS)

Liu, Lian; Yang, Xiukun; Zhong, Mingliang; Liu, Yao; Jing, Xiaojun; Yang, Qin

2018-04-01

The discrete fractional Brownian incremental random (DFBIR) field is used to describe the irregular, random, and highly complex shapes of natural objects such as coastlines and biological tissues, for which traditional Euclidean geometry cannot be used. In this paper, an anisotropic variable window (AVW) directional operator based on the DFBIR field model is proposed for extracting spatial characteristics of Fourier transform infrared spectroscopy (FTIR) microscopic imaging. Probabilistic principal component analysis first extracts spectral features, and then the spatial features of the proposed AVW directional operator are combined with the former to construct a spatial-spectral structure, which increases feature-related information and helps a support vector machine classifier to obtain more efficient distribution-related information. Compared to Haralick’s grey-level co-occurrence matrix, Gabor filters, and local binary patterns (e.g. uniform LBPs, rotation-invariant LBPs, uniform rotation-invariant LBPs), experiments on three FTIR spectroscopy microscopic imaging datasets show that the proposed AVW directional operator is more advantageous in terms of classification accuracy, particularly for low-dimensional spaces of spatial characteristics.

A Transmission Electron Microscope Investigation of Space Weathering Effects in Hayabusa Samples

NASA Technical Reports Server (NTRS)

Keller, Lindsay P.; Berger, Eve L.

2014-01-01

The Hayabusa mission to asteroid 25143 Itokawa successfully returned the first direct samples of the regolith from the surface of an asteroid. The Hayabusa samples thus present a special opportunity to directly investigate the evolution of asteroidal surfaces, from the development of the regolith to the study of the more complex effects of space weathering. Here we describe the mineralogy, microstructure and composition of three Hayabusa mission particles using transmission electron microscope (TEM) techniques

Characterization of some biological specimens using TEM and SEM

NASA Astrophysics Data System (ADS)

Ghosh, Nabarun; Smith, Don W.

2009-05-01

The advent of novel techniques using the Transmission and Scanning Electron Microscopes improved observation on various biological specimens to characterize them. We studied some biological specimens using Transmission and Scanning Electron Microscopes. We followed negative staining technique with Phosphotungstic acid using bacterial culture of Bacillus subtilis. Negative staining is very convenient technique to view the structural morphology of different samples including bacteria, phage viruses and filaments in a cell. We could observe the bacterial cell wall and flagellum very well when trapped the negative stained biofilm from bacterial culture on a TEM grid. We cut ultra thin sections from the fixed root tips of Pisum sativum (Garden pea). Root tips were pre fixed with osmium tetroxide and post fixed with uranium acetate and placed in the BEEM capsule for block making. The ultrathin sections on the grid under TEM showed the granular chromatin in the nucleus. The protein bodies and large vacuoles with the storage materials were conspicuous. We followed fixation, critical point drying and sputter coating with gold to view the tissues with SEM after placing on stubs. SEM view of the leaf surface of a dangerous weed Tragia hispida showed the surface trichomes. These trichomes when break on touching releases poisonous content causing skin irritation. The cultured tissue from in vitro culture of Albizia lebbeck, a tree revealed the regenerative structures including leaf buds and stomata on the tissue surface. SEM and TEM allow investigating the minute details characteristic morphological features that can be used for classroom teaching.

Label-Free Ferrocene-Loaded Nanocarrier Engineering for In Vivo Cochlear Drug Delivery and Imaging.

PubMed

Youm, Ibrahima; Musazzi, Umberto M; Gratton, Michael Anne; Murowchick, James B; Youan, Bi-Botti C

2016-10-01

It is hypothesized that ferrocene (FC)-loaded nanocarriers (FC-NCs) are safe label-free contrast agents for cochlear biodistribution study by transmission electron microscopy (TEM). To test this hypothesis, after engineering, the poly(epsilon-caprolactone)/polyglycolide NCs are tested for stability with various types and ratios of sugar cryoprotectants during freeze-drying. Their physicochemical properties are characterized by UV-visible spectroscopy, dynamic light scattering, Fourier transform infrared spectroscopy, and scanning electron microscopy coupled with energy dispersive X-ray spectroscopy (SEM/EDS). The biodistribution of the FC-NCs in the cochlear tissue after intratympanic injection in guinea pigs is visualized by TEM. Auditory brainstem responses are measured before and after 4-day treatments. These FC-NCs have 153.4 ± 8.7 nm, 85.5 ± 11.2%, and -22.1 ± 1.1 mV as mean diameters, percent drug association efficiency, and zeta potential, respectively (n = 3). The incorporation of FC into the NCs is confirmed by Fourier transform infrared spectroscopy and SEM/EDS spectra. Lactose (3:1 ratio, v/v) is the most effective stabilizer after a 12-day study. The administered NCs are visible by TEM in the scala media cells of the cochlea. Based on auditory brainstem response data, FC-NCs do not adversely affect hearing. Considering the electrondense, radioactive, and magnetic properties of iron inside FC, FC-NCs are promising nanotemplate for future inner ear theranostics. Copyright © 2016 American Pharmacists Association®. Published by Elsevier Inc. All rights reserved.

A new formulation of curcumin using poly (lactic-co-glycolic acid)—polyethylene glycol diblock copolymer as carrier material

NASA Astrophysics Data System (ADS)

Phuong Tuyen Dao, Thi; Hoai Nguyen, To; To, Van Vinh; Ho, Thanh Ha; Nguyen, Tuan Anh; Chien Dang, Mau

2014-09-01

The aim of this study is to fabricate a nanoparticle formulation of curcumin using a relatively new vehicle as the matrix polymer: poly(lactic-co-glycolic acid) (PLGA)- polyethylene glycol (PEG) diblock copolymer, and to investigate the effects of the various processing parameters on the characteristics of nanoparticles (NPs). We successfully synthesized the matrix polymer of PLGA-PEG by conjugation of PLGA copolymer with a carboxylate end group to a heterobifunctional amine-PEG-methoxy using N-(3-dimethylaminopropyl)-N’-ethylcarbodiimide hydrochloride and N-hydroxysuccinimide as conjugation crosslinkers. The composition of the formed product (PLGA-PEG) was characterized with 500 MHz 1H nuclear magnetic resonance (NMR). The conjugation of PLGA-PEG was confirmed using Fourier transform infrared (FTIR) spectrum study. This diblock copolymer was then used to prepare the curcumin-loaded NPs through nanoprecipitation technique. With this method, we found that the size distribution depends on the type of solvent, the concentration of polymer and the concentration of surfactant. The particle size and size distribution were measured by dynamic light scattering (DLS). Transmission electron microscope (TEM) and scanning electron microscope (SEM) were used to confirm the size, structure and morphology of the successfully prepared NPs. All of our results showed that they are spherical and quite homologous with mean diameter around of 100-300 nm. Further, we evaluated encapsulation efficiency and some characteristics of NPs through high performance liquid chromatography (HPLC) analyses, zeta-potential measurements and x-ray diffraction studies. The HPLC analyses were performed to determine the amount of curcumin entrapped in NPs. The zeta-potential measurements confirmed the stability of NPs and the successful encapsulation of curcumin within NPs and the x-ray diffraction patterns showed the disordered-crystalline phase of curcumin inside the polymeric matrix.

Bio-synthesis of silver nanoparticles using Potentilla fulgens Wall. ex Hook. and its therapeutic evaluation as anticancer and antimicrobial agent.

PubMed

Mittal, Amit Kumar; Tripathy, Debabrata; Choudhary, Alka; Aili, Pavan Kumar; Chatterjee, Anupam; Singh, Inder Pal; Banerjee, Uttam Chand

2015-08-01

The present study aims to develop an easy and eco-friendly method for the synthesis of silver nanoparticles using extracts from the medicinal plant, Potentilla fulgens and evaluation of its anticancer and antimicrobial properties. The various parts of P. fulgens were screened and the root extract was found to have the highest potential for the synthesis of nanoparticles. The root extracts were able to quickly reduce Ag(+) to Ag(0) and stabilized the nanoparticles. The synthesis of nanoparticles was confirmed by UV-Visible spectrophotometry and further characterized using Zeta sizer, Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), transmission electron microscope (TEM) and X-ray diffraction (XRD). Electron microscopic study showed that the size of the nanoparticle was in the range of 10 to 15 nm and spherical in shape. The studies of phytochemical analysis of nanoparticles indicated that the adsorbed components on the surface of nanoparticles were mainly flavonoid in nature. Furthermore, nanoparticles were evaluated as cytotoxic against various cancer cell lines and 0.2 to 12 μg/mL nanoparticles showed good toxicity. The IC50 value of nanoparticles was found to be 4.91 and 8.23 μg/mL against MCF-7 and U-87 cell lines, respectively. Additionally, the apoptotic effect of synthesized nanoparticles on normal and cancer cells was studied using trypan blue assay and flow-cytometric analysis. The results indicate the synthesized nanoparticle ability to kill cancer cells compared to normal cells. The nanoparticles also exhibited comparable antimicrobial activity against both Gram-positive and Gram-negative bacteria. Copyright © 2015 Elsevier B.V. All rights reserved.

A novel electrochemical sensor for detecting hyperin with a nanocomposite of ZrO2-SDS-SWCNTs as decoration.

PubMed

Li, Shuo; Lei, Sheng; Yu, Qian; Zou, Lina; Ye, Baoxian

2018-08-01

A novel high-sensitive electrochemical sensor with glassy carbon electrode (GCE) as support for hyperin determination is successfully designed and constructed, and the well-shaped nano-meter modified material is synthesized via a one-step and facile route. Functionalized with surfactant sodium dodecyl sulfate (SDS), Single-Walled Carbon Nanotubes (SWCNTs) are synchronously grafted with ZrO 2 nanoparticles to develop into the as-prepared nano-composite (ZrO 2 -SDS-SWCNTs). Compared to the previous reports related with hyperin detection, the linear range gets wider and detection limit (LOD) becomes lower with the aid of this novel nano-composite modified glassy carbon electrode (ZrO 2 -SDS-SWCNTs/GCE). The crystalline phases and functionalization of the preparation process has been investigated by X-ray diffraction (XRD) and Fourier transform infrared (FT-IR) instrument analysis, respectively, and the micro-morphology of related modified materials is also visibly characterized by scanning electron microscope (SEM) and transmission electron microscope (TEM). In addition, electrochemical properties of the modified materials are comparably explored by means of impedance spectroscopy (EIS) and cyclic voltammograms (CV). According to the established calibration curve under optimized condition, the peak current (Differential pulse voltammetry (DPV) signal) keeps a linear relationship with hyperin concentration in the ranges of 1.0 × 10 -9 - 3.0 × 10 -7 mol L -1 , meanwhile detection limit reaches as low as 5 × 10 -10 mol L -1 (S/N = 3). As for practical applications, the proposed sensor has also worked well on sensitive hyperin determination in real species Abelmoschus manihot. Copyright © 2018 Elsevier B.V. All rights reserved.

Preparation, characterization and application of dispersible and spherical Nano-SiO2@Copolymer nanocomposite in leather tanning

NASA Astrophysics Data System (ADS)

Pan, Hui; Li, Guang-Long; Liu, Rui-Qi; Wang, Su-Xia; Wang, Xiao-Dong

2017-12-01

Dispersible and spherical silica nanoparticles (nano-SiO2) were prepared with tetraethyl silicate and different surface-modifiers via a simple method. The silica nanoparticles surface-modified with methacryloxy (propyl) trimethoxysilane (denoted as MPS-SiO2), dimethyl diallyl ammoniumchloride (denoted as DMDAAC-SiO2) and poly (methacrylic acid) (denoted as PMAA-SiO2) which are known as hydrophobic, amphiphilic and hydrophilic modifiers, respectively, exhibited excellent dispersibility in various solvents or polymer matrix. The obtained bare silica nanoparticles, MPS-SiO2, DMDAAC-SiO2 and PMAA-SiO2 were characterized by Fourier transform infrared spectra (FTIR), thermogravimetric analysis (TGA), transmission electron microscope (TEM) and scanning electron microscope (SEM). A series of nanocomposites (denoted as SiO2/P, MPS-SiO2/P, DMDAAC-SiO2/P and PMAA-SiO2/P, respectively) were also prepared with the bare or surface-modified silica nanoparticles and methacrylic acid-co-acrylamide-co-acrylonitrile-co-salicylic acid tetrabasic copolymer (denoted as PMAAS) and applied in leather tanning. Compared with those of the leather tanned with the commercial acrylic resin (CHINATAN OM) and pure tetrabasic copolymer tanning agents, the physical and mechanical properties, rheological properties and thermal stabilities of the leather treated with SiO2/P, MPS-SiO2/P, DMDAAC-SiO2/P or PMAA-SiO2/P founded to be improved in a significant way. Moreover, the highest shrinkage temperature of the wet-white sheepskin tanned with PMAA-SiO2/P reached to 76 °C and the thickness increase reached to 105%.

Numerical restoration of surface vortices in Nb films measured by a scanning SQUID microscope

NASA Astrophysics Data System (ADS)

Ito, Atsuki; Thanh Huy, Ho; Dang, Vu The; Miyoshi, Hiroki; Hayashi, Masahiko; Ishida, Takekazu

2017-07-01

In the present work, we investigated a vortex profile appeared on a pure Nb film (500 nm in thickness, 10 mm x 10 mm) by using a scanning SQUID microscope. We found that the local magnetic distribution thus observed is broadened compared to a true vortex profile in the superconducting film. We therefore applied the numerical method to improve a spatial resolution of the scanning SQUID microscope. The method is based on the inverse Biot-Savart law and the Fourier transformation to recover a real-space image. We found that the numerical analyses give a smaller vortex than the raw vortex profile observed by the scanning microscope.

Bio-inspired sustainable and green synthesis of plasmonic Ag/AgCl nanoparticles for enhanced degradation of organic compound from aqueous phase.

PubMed

Devi, Th Babita; Ahmaruzzaman, M

2016-09-01

In the current study, we report the utilization of the biogenic potential of Benincasa hispida (ash gourd) peel extract for the synthesis of Ag embedded AgCl nanoparticles nanoparticles (Ag/AgCl NPs) without the use of any external organic solvents. The appearance of dark brown color from the pale yellow color confirmed the formation of Ag/AgCl nanoparticles which was further validated by absorbance peak using UV-visible spectroscopy. The phytochemicals (flavones) present in the B. hispida peel extract acts as a reducing/stabilizing agents. The morphology and size of the synthesized NPs were characterized by transmission electron microscope (TEM), selected area electron microscope (SAED) and high resolution transmission electron microscope (HR-TEM). FT-IR spectra of the B. hispida peel extract and after the development of nanoparticles are determined to identify the functional groups responsible for the conversion of metal ions to metal nanoparticles. The synthesized nanoparticles showed an excellent photocatalytic property in the degradation of toxic dye like malachite green oxalate under sunlight irradiation. For the first time, malachite green oxalate dye was degraded by Ag/AgCl nanoparticles under sunlight irradiation.

Comments on ”Evidence of the hydrogen release mechanism in bulk MgH2”

NASA Astrophysics Data System (ADS)

Surrey, Alexander; Nielsch, Kornelius; Rellinghaus, Bernd

2017-04-01

The effect of an electron beam induced dehydrogenation of MgH2 in the transmission electron microscope (TEM) is largely underestimated by Nogita et al., and led the authors to a misinterpretation of their TEM observations. Firstly, the selected area diffraction (SAD) pattern is falsely interpreted. A re-evaluation of the SAD pattern reveals that no MgH2 is present in the sample, but that it rather consists of Mg and MgO only. Secondly, the transformation of the sample upon in-situ heating in the TEM cannot be ascribed to dehydrogenation, but is rather to be explained by the (nanoscale) Kirkendall effect, which leads to the formation of hollow MgO shells without any metallic Mg in their cores. Hence, the conclusions drawn from the TEM investigation are invalid, as the authors apparently have never studied MgH2.

Development of 1500mm Wide Wrought Magnesium Alloys by Twin Roll Casting Technique in Turkey

NASA Astrophysics Data System (ADS)

Duygulu, Ozgur; Ucuncuoglu, Selda; Oktay, Gizem; Temur, Deniz Sultan; Yucel, Onuralp; Kaya, Ali Arslan

Magnesium alloy AZ31, AZ61, AZ91, AM50 and AM60 sheets were produced by twin roll casting first time in Turkey. Sheets of 4.5-6.5mm thick and 1500mm width were successfully achieved. Microstructure of the sheet was analyzed by optical microscope, scanning electron microscope (SEM) and transmission electron microscope (TEM). Semi-quantitative analyses were performed by SEM-EDS. In addition, X-ray studies were performed for both characterization and texture purposes. Mechanical properties were investigated by tensile tests and also hardness measurements. Homogenization and annealing heat treatments were performed on the produced sheets.

Real-time quantum cascade laser-based infrared microspectroscopy in-vivo

NASA Astrophysics Data System (ADS)

Kröger-Lui, N.; Haase, K.; Pucci, A.; Schönhals, A.; Petrich, W.

2016-03-01

Infrared microscopy can be performed to observe dynamic processes on a microscopic scale. Fourier-transform infrared spectroscopy-based microscopes are bound to limitations regarding time resolution, which hampers their potential for imaging fast moving systems. In this manuscript we present a quantum cascade laser-based infrared microscope which overcomes these limitations and readily achieves standard video frame rates. The capabilities of our setup are demonstrated by observing dynamical processes at their specific time scales: fermentation, slow moving Amoeba Proteus and fast moving Caenorhabditis elegans. Mid-infrared sampling rates between 30 min and 20 ms are demonstrated.

An electron energy loss spectrometer based streak camera for time resolved TEM measurements.

PubMed

Ali, Hasan; Eriksson, Johan; Li, Hu; Jafri, S Hassan M; Kumar, M S Sharath; Ögren, Jim; Ziemann, Volker; Leifer, Klaus

2017-05-01

We propose an experimental setup based on a streak camera approach inside an energy filter to measure time resolved properties of materials in the transmission electron microscope (TEM). In order to put in place the streak camera, a beam sweeper was built inside an energy filter. After exciting the TEM sample, the beam is swept across the CCD camera of the filter. We describe different parts of the setup at the example of a magnetic measurement. This setup is capable to acquire time resolved diffraction patterns, electron energy loss spectra (EELS) and images with total streaking times in the range between 100ns and 10μs. Copyright © 2016 Elsevier B.V. All rights reserved.

A sensitive glucose biosensor based on Ag@C core-shell matrix.

PubMed

Zhou, Xuan; Dai, Xingxin; Li, Jianguo; Long, Yumei; Li, Weifeng; Tu, Yifeng

2015-04-01

Nano-Ag particles were coated with colloidal carbon (Ag@C) to improve its biocompatibility and chemical stability for the preparation of biosensor. The core-shell structure was evidenced by transmission electron microscope (TEM) and the Fourier transfer infrared (FTIR) spectra revealed that the carbon shell is rich of function groups such as -OH and -COOH. The as-prepared Ag@C core-shell structure can offer favorable microenvironment for immobilizing glucose oxidase and the direct electrochemistry process of glucose oxidase (GOD) at Ag@C modified glassy carbon electrode (GCE) was realized. The modified electrode exhibited good response to glucose. Under optimum experimental conditions the biosensor linearly responded to glucose concentration in the range of 0.05-2.5mM, with a detection limit of 0.02mM (S/N=3). The apparent Michaelis-Menten constant (KM(app)) of the biosensor is calculated to be 1.7mM, suggesting high enzymatic activity and affinity toward glucose. In addition, the GOD-Ag@C/Nafion/GCE shows good reproducibility and long-term stability. These results suggested that core-shell structured Ag@C is an ideal matrix for the immobilization of the redox enzymes and further the construction of the sensitive enzyme biosensor. Copyright © 2015 Elsevier B.V. All rights reserved.

Preparation and properties of hybrid monodispersed magnetic α-Fe2O3 based chitosan nanocomposite film for industrial and biomedical applications.

PubMed

Singh, Jay; Srivastava, M; Dutta, Joydeep; Dutta, P K

2011-01-01

In this study, hydrothermally prepared magnetic α-Fe2O3 nanoparticles were dispersed in chitosan (CH) solution to fabricate nanocomposite film. X-ray diffraction (XRD) patterns indicated that the α-Fe2O3 nanoparticles were pure α-Fe2O3 with rhombohedral structures, and the fabrication of CH did not result in a phase change. The scanning electron microscopy (SEM) and transmission electron microscope (TEM) results showed that the hexagonal and spherical monodispersed α-Fe2O3 nanoparticles were encapsulated into the spherical dumb shaped CH-α-Fe2O3 nanocomposite film with a mean diameter of ∼87 and ∼110 nm respectively. The α-Fe2O3 nanoparticles and CH-α-Fe2O3 nanocomposite film were also characterized by Fourier transform infrared (FTIR) spectroscopy, thermogravimetric analysis (TGA), differential scanning calorimetry (DSC) and vibrating sample magnetometer (VSM). Magnetic measurements revealed that the saturated magnetization (Ms) and remanent magnetization (Mr) of the pure α-Fe2O3 nanoparticles reached 0.573 emu/g and 0.100 emu/g respectively and the nanoparticles showed the characteristics of weak ferromagnetic before and after coating with CH. Copyright © 2010 Elsevier B.V. All rights reserved.

Preparation and characterization of poly(AA co PVP)/PGS composite and its application for methylene blue adsorption.

PubMed

Yang, Cai-xia; Lei, Lei; Zhou, Peng-xin; Zhang, Zhe; Lei, Zi-qiang

2015-04-01

Poly (AA co PVP)/PGS (PAPP) composite adsorbent was prepared by radical polymerization from Acrylic acid (AA), Polyvinylpyrrolidone (PVP) and Palygorskite (PGS), using N,N-methylenebisacrylamide (MBA) as cross-linker and potassium persulfate (KPS) as initiator. The PAPP was characterized with Fourier transform infrared (FT-IR), thermogravimetric analysis (TG), scanning electron microscope (SEM) and transmission electron microscopy (TEM). PAPP was used as adsorbent for the removal of methylene blue from aqueous solutions. The influences of pH, adsorption temperature and adsorption time on the adsorption properties of the composite to the dye were also investigated. Meanwhile, the adsorption rate data and adsorption equilibrium date were analyzed based on the pseudo-first-order and pseudo-second-order kinetic model, Langmuir and Freundlich isotherm models, respectively. The results indicating that the kinetic behavior better fit with the pseudo-second-order kinetic model. The maximum equilibrium adsorption capacity (q(m)) is 1815 mg/g at 289 K. The isotherm behavior can be explained by the Langmuir isotherm models. The activation energy was also evaluated for the removal of methylene blue onto PAPP. These results demonstrate that this composite material could be used as a good adsorbent for the removal of cationic dyes from wastewater. Copyright © 2014 Elsevier Inc. All rights reserved.

Preparation and electrochemical characterization of polyaniline/activated carbon composites as an electrode material for supercapacitors.

PubMed

Oh, Misoon; Kim, Seok

2012-01-01

Polyaniline (PANI)/activated carbon (AC) composites were prepared by a chemical oxidation polymerization. To find an optimum ratio between PANI and AC which shows superior electrochemical properties, the preparation was carried out in changing the amount of added aniline monomers. The morphology of prepared composites was investigated by scanning electron microscopy (SEM) and transmission electron microscope (TEM). The structural and thermal properties were investigated by Fourier transform infrared spectra (FT-IR) and thermal gravimetric analysis (TGA), respectively. The electrochemical properties were characterized by cyclic voltammetry (CV). Composites showed a summation of capacitances that consisted of two origins. One is double-layer capacitance by ACs and the other is faradic capacitance by redox reaction of PANI. Fiber-like PANIs are coated on the surface of ACs and they contribute to the large surface for redox reaction. The vacancy among fibers provided the better diffusion and accessibility of ion. High capacitances of composites were originated from the network structure having vacancy made by PANI fibers. It was found that the composite prepared with 5 ml of aniline monomer and 0.25 g of AC showed the highest capacitance. Capacitance of 771 F/g was obtained at a scan rate of 5 mV/s.

Electrical, structural and thermal studies of carbon nanotubes from natural legume seeds: kala chana

NASA Astrophysics Data System (ADS)

Ranu, Rachana; Chauhan, Yatishwar; Singh, Pramod K.; Bhattacharya, B.; Tomar, S. K.

2016-12-01

Carbon nanotubes (CNTs) are the carbon materials measured at nanoscale level and they are defined in two types according to the number of concentric layers, i.e. single-layer tube is single-walled nanotubes, while multi-layer tube structure is called multi-walled nanotubes. The green method synthesis for the preparation of CNTs begins with the smashing of legume seeds kala chana, and then they form complex with cobalt salt. Desiccation of the complex compound forms cobalt salt and seed protein. The complex is then decomposed at 625 °C in muffle furnace for 20 min. Purification of the decomposed sample is done through acid wash treatment and dried in vacuum oven. The confirmations of CNTs are done by nuclear magnetic resonance and Fourier transform infrared, which analyzes the denatured protein, reacted to the metal salt. X-Ray diffraction determines the MWNTs with transmission electron microscope (TEM) reports the network structure of CNTs. thermal gravimetric analysis (TGA)-differential thermal analysis (DTA)-thermogravimetric analysis (DTG) tests the amount of sample under thermal treatment. Vibrating sample magnetometer determines the paramagnetic nature of CNTs. CNTs thus prepared can be used in mechanical fields, in solar cells, in electronics fields, etc. because of their multidisciplinary properties. The synthesized CNTs are eco-friendly in nature, prepared by the legume seed natural precursor.

Electrochemical Reduction of CO2 to Organic Acids by a Pd-MWNTs Gas-Diffusion Electrode in Aqueous Medium

PubMed Central

Lu, Guang; Bian, Zhaoyong; Liu, Xin

2013-01-01

Pd-multiwalled carbon nanotubes (Pd-MWNTs) catalysts for the conversion of CO2 to organic acids were prepared by the ethylene glycol reduction and fully characterized by Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), transmission electron microscope (TEM), X-ray photoelectron spectroscopy (XPS), and cyclic voltammetry (CV) technologies. The amorphous Pd particles with an average size of 5.7 nm were highly dispersed on the surface of carbon nanotubes. Functional groups of the MWNTs played a key role in the palladium deposition. The results indicated that Pd-MWNTs could transform CO2 into organic acid with high catalytic activity and CO2 could take part in the reduction reaction directly. Additionally, the electrochemical reduction of CO2 was investigated by a diaphragm electrolysis device, using a Pd-MWNTs gas-diffusion electrode as a cathode and a Ti/RuO2 net as an anode. The main products in present system were formic acid and acetic acid identified by ion chromatograph. The selectivity of the products could be achieved by reaction conditions changing. The optimum faraday efficiencies of formic and acetic acids formed on the Pd-MWNTs gas-diffusion electrode at 4 V electrode voltages under 1 atm CO2 were 34.5% and 52.3%, respectively. PMID:24453849

Preparation of epoxy-acrylate copolymer/nano-silica via Pickering emulsion polymerization and its application as printing binder

NASA Astrophysics Data System (ADS)

Gao, Dangge; Chang, Rui; Lyu, Bin; Ma, Jianzhong; Duan, Xiying

2018-03-01

This paper presents a facile and efficient synthesis method to fabricate epoxy-acrylate copolymer/nano-silica latex via Pickering emulsion polymerization stabilized by silica sol. The effects of solid contents, silica concentration and polymerization time on emulsion polymerization were studied. The core-shell epoxy-acrylate copolymer/nano-silica was obtained with average diameter 690 nm, was observed by Transmission Electron Microscopy (TEM) and Dynamic Light Scattering (DLS). The formation mechanism of epoxy-acrylate copolymer/nano-silica emulsion polymerization was proposed through observing the morphology of latex particles at different polymerization time. Fourier Transformation Infrared (FT-IR) and Thermogravimetric Analysis (TGA) were used to study structure and thermostability of the composites. Morphology of the latex film was characterized by Scanning Electron Microscope (SEM). The results indicated that nano-silica particles existed in the composite emulsion and could improve the thermal stability of the film. The epoxy-acrylate copolymer/nano-silica latex was used as binder applied to cotton fabric for pigment printing. The application results demonstrated that Pickering emulsion stabilized by silica sol has good effects in the pigment printing binder without surfactant. Compared with commodity binder, the resistance to wet rubbing fastness and soaping fastness were improved half grade.

Structural, optical and magnetic properties of gadolinium sesquioxide nanobars synthesized via thermal decomposition of gadolinium oxalate

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

Manigandan, R.; Giribabu, K.; Suresh, R.

2013-10-15

Graphical abstract: - Highlights: • The cubic Gd{sub 2}O{sub 3} nanobars are synthesized by decomposition of C{sub 6}H{sub 20}Gd{sub 2}O{sub 22}. • The nanoparticles are rectangular bar shape with high porous surface. • The combination of magnetic and optical properties within a single particle. • The Gd{sub 2}O{sub 3} nanobars have tailorable nanostructure, wide bandgap and are paramagnetic. - Abstract: Gadolinium oxide nanobars were obtained by thermal decomposition of gadolinium oxalate, which was synthesized by the chemical precipitation method along with glycerol. The functional group analysis and formation of gadolinium oxide from gadolinium oxalate were characterized by the Fourier transformmore » infrared spectroscopy and thermo gravimetric analyzer. The crystal structure, average crystallite size, and lattice parameter were analyzed by X-ray diffraction technique. Moreover, Raman shifts, elemental composition and morphology of the gadolinium oxide was widely investigated by the laser Raman microscope, X-ray photoelectron spectroscopy, FE-SEM-EDAX and HR-TEM, respectively. Furthermore, the optical properties like band gap, absorbance measurement of the gadolinium oxide were extensively examined. In addition, the paramagnetic property of gadolinium oxide nanobars was explored by the vibrating sample magnetometer.« less

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

NASA Astrophysics Data System (ADS)

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

2017-10-01

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

The structure-directed effect of Al-based metal–organic frameworks on fabrication of alumina by thermal treatment

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

Liu, Dandan, E-mail: liudandan_upc@126.com; Dai, Fangna, E-mail: fndai@upc.edu.cn; Collage of Science, China University of Petroleum

2015-05-15

Highlights: • We use Al-MOFs as precursor in the fabrication process of mesoporous alumina by thermal treatment. • The obtained mesoporous alumina has dual pore system and five-fold aluminum. • The aluminum building units in the precursor show structure-directed effect on the formation of alumina. - Abstract: In this work, the block-shaped Al-based metal–organic frameworks (Al-MOFs) MIL-53 have been synthesized by hydrothermal method. To detect the correlation between the structure of Al-MOFs and the formation of alumina, the ligands are eliminated by thermal treatment. MIL-53 and the calcination products were characterized by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR),more » scanning electron microscope (SEM), transmission electron microscopy (TEM), nitrogen adsorption–desorption and solid-state {sup 27}Al nuclear magnetic resonance ({sup 27}Al NMR). It was found that after calcination, the block-shaped Al-MOFs precursor turns into high-crystallinity mesoporous alumina nanosheets, and the thermal treatment product γ-alumina possesses a dual pore system and a large surface area (146 m{sup 2}/g), with five-fold aluminum. During the thermal treatment process, the structure of MIL-53 and its secondary building units have structure-directed effect in the formation of alumina.« less

Evaluation of antibacterial efficacy of phyto fabricated silver nanoparticles using Mukia scabrella (Musumusukkai) against drug resistance nosocomial gram negative bacterial pathogens.

PubMed

Prabakar, Kandasamy; Sivalingam, Periyasamy; Mohamed Rabeek, Siyed Ibrahim; Muthuselvam, Manickam; Devarajan, Naresh; Arjunan, Annavi; Karthick, Rajamanickam; Suresh, Micky Maray; Wembonyama, John Pote

2013-04-01

Given the fact in the limitation of the therapeutic options for emerging multidrug resistance gram-negative bacteria (MDR-GNB) of respiratory tract infections, the present study was focused on green synthesis of antimicrobial silver nanoparticles (AgNPs) using leaf extract of Mukia scabrella. An obvious color change to brown color and surface plasmon resonance by UV-visible spectroscopy (UV-vis) indicated a well observable peak at 440 nm confirming the synthesis of AgNPs. Fourier transform infra-red spectroscopy (FTIR) analysis indicates protein as possible capping agents. Energy dispersive X-ray (EDAX) spectroscopy results showed major signal for elemental silver. X-ray diffraction (XRD) analysis indicates the formation of metallic silver nanomaterials. Transmission electron microscopic (TEM) study showed the nanoparticles in the size range of 18-21 nm with spherical shape. Zeta potential analysis showed -21.7 mV characteristic for stable AgNPs. The biosynthesized AgNPs exhibited significant antimicrobial activity against MDR-GNB nosocomial pathogens of Acinetobacter sp., Klebsiella pneumoniae and Pseudomonas aeruginosa. Results from the current study suggested that M. scabrella material could be exploited for the fabrication of AgNPs with potential therapeutic applications in nanomedicine especially for nosocomial bacterial infections. Copyright © 2012 Elsevier B.V. All rights reserved.

Adaptive Neuro-Fuzzy Inference system analysis on adsorption studies of Reactive Red 198 from aqueous solution by SBA-15/CTAB composite

NASA Astrophysics Data System (ADS)

Aghajani, Khadijeh; Tayebi, Habib-Allah

2017-01-01

In this study, the Mesoporous material SBA-15 were synthesized and then, the surface was modified by the surfactant Cetyltrimethylammoniumbromide (CTAB). Finally, the obtained adsorbent was used in order to remove Reactive Red 198 (RR 198) from aqueous solution. Transmission electron microscope (TEM), Fourier transform infra-red spectroscopy (FTIR), Thermogravimetric analysis (TGA), X-ray diffraction (XRD), and BET were utilized for the purpose of examining the structural characteristics of obtained adsorbent. Parameters affecting the removal of RR 198 such as pH, the amount of adsorbent, and contact time were investigated at various temperatures and were also optimized. The obtained optimized condition is as follows: pH = 2, time = 60 min and adsorbent dose = 1 g/l. Moreover, a predictive model based on ANFIS for predicting the adsorption amount according to the input variables is presented. The presented model can be used for predicting the adsorption rate based on the input variables include temperature, pH, time, dosage, concentration. The error between actual and approximated output confirm the high accuracy of the proposed model in the prediction process. This fact results in cost reduction because prediction can be done without resorting to costly experimental efforts. SBA-15, CTAB, Reactive Red 198, adsorption study, Adaptive Neuro-Fuzzy Inference systems (ANFIS).

Collaborative Research and Development (CR&D). Delivery Order 0051: Atomic Scale Transmission Electron Microscope Image Modeling and Application to Semiconductor Heterointerface Characterization

DTIC Science & Technology

2008-01-01

information if it does not display a currently valid OMB control number. PLEASE DO NOT RETURN YOUR FORM TO THE ABOVE ADDRESS. 1. REPORT DATE (DD...microscopy ( AEM ), to characterize a variety of III-V semiconductor thin films. The materials investigated include superlattices based on the InAs- GaSb...technique. TEM observations were performed using a Philips-CM 200 FEG transmission electron microscope equipped with a field emission gun, operated at an

Transmission Electron Microscope Measures Lattice Parameters

NASA Technical Reports Server (NTRS)

Pike, William T.

1996-01-01

Convergent-beam microdiffraction (CBM) in thermionic-emission transmission electron microscope (TEM) is technique for measuring lattice parameters of nanometer-sized specimens of crystalline materials. Lattice parameters determined by use of CBM accurate to within few parts in thousand. Technique developed especially for use in quantifying lattice parameters, and thus strains, in epitaxial mismatched-crystal-lattice multilayer structures in multiple-quantum-well and other advanced semiconductor electronic devices. Ability to determine strains in indivdual layers contributes to understanding of novel electronic behaviors of devices.

Ponderomotive phase plate for transmission electron microscopes

DOEpatents

Reed, Bryan W [Livermore, CA

2012-07-10

A ponderomotive phase plate system and method for controllably producing highly tunable phase contrast transfer functions in a transmission electron microscope (TEM) for high resolution and biological phase contrast imaging. The system and method includes a laser source and a beam transport system to produce a focused laser crossover as a phase plate, so that a ponderomotive potential of the focused laser crossover produces a scattering-angle-dependent phase shift in the electrons of the post-sample electron beam corresponding to a desired phase contrast transfer function.

Crossover from ballistic to normal heat transport in the ϕ4 lattice: If nonconservation of momentum is the reason, what is the mechanism?

NASA Astrophysics Data System (ADS)

Xiong, Daxing; Saadatmand, Danial; Dmitriev, Sergey V.

2017-10-01

Anomalous (non-Fourier) heat transport is no longer just a theoretical issue since it has been observed experimentally in a number of low-dimensional nanomaterials, such as SiGe nanowires, carbon nanotubes, and others. To understand these anomalous behaviors, exploring the microscopic origin of normal (Fourier) heat transport is a fascinating theoretical topic. However, this issue has not yet been fully understood even for one-dimensional (1D) model chains, in spite of a great amount of thorough studies done to date. From those studies, it has been widely accepted that the conservation of momentum is a key ingredient to induce anomalous heat transport, while momentum-nonconserving systems usually support normal heat transport where Fourier's law is valid. But if the nonconservation of momentum is the reason, what is the underlying microscopic mechanism for the observed normal heat transport? Here we carefully revisit a typical 1D momentum-nonconserving ϕ4 model, and we present evidence that the mobile discrete breathers, or, in other words, the moving intrinsic localized modes with frequency components above the linear phonon band, can be responsible for that.

High-resolution retinal imaging using adaptive optics and Fourier-domain optical coherence tomography

DOEpatents

Olivier, Scot S.; Werner, John S.; Zawadzki, Robert J.; Laut, Sophie P.; Jones, Steven M.

2010-09-07

This invention permits retinal images to be acquired at high speed and with unprecedented resolution in three dimensions (4.times.4.times.6 .mu.m). The instrument achieves high lateral resolution by using adaptive optics to correct optical aberrations of the human eye in real time. High axial resolution and high speed are made possible by the use of Fourier-domain optical coherence tomography. Using this system, we have demonstrated the ability to image microscopic blood vessels and the cone photoreceptor mosaic.

Quasi-parallel precession diffraction: Alignment method for scanning transmission electron microscopes.

PubMed

Plana-Ruiz, S; Portillo, J; Estradé, S; Peiró, F; Kolb, Ute; Nicolopoulos, S

2018-06-06

A general method to set illuminating conditions for selectable beam convergence and probe size is presented in this work for Transmission Electron Microscopes (TEM) fitted with µs/pixel fast beam scanning control, (S)TEM, and an annular dark field detector. The case of interest of beam convergence and probe size, which enables diffraction pattern indexation, is then used as a starting point in this work to add 100 Hz precession to the beam while imaging the specimen at a fast rate and keeping the projector system in diffraction mode. The described systematic alignment method for the adjustment of beam precession on the specimen plane while scanning at fast rates is mainly based on the sharpness of the precessed STEM image. The complete alignment method for parallel condition and precession, Quasi-Parallel PED-STEM, is presented in block diagram scheme, as it has been tested on a variety of instruments. The immediate application of this methodology is that it renders the TEM column ready for the acquisition of Precessed Electron Diffraction Tomographies (EDT) as well as for the acquisition of slow Precessed Scanning Nanometer Electron Diffraction (SNED). Examples of the quality of the Precessed Electron Diffraction (PED) patterns and PED-STEM alignment images are presented with corresponding probe sizes and convergence angles. Copyright © 2018. Published by Elsevier B.V.

Microwave-assisted hydrothermal synthesis of biocompatible silver sulfide nanoworms

NASA Astrophysics Data System (ADS)

Xing, Ruimin; Liu, Shanhu; Tian, Shufang

2011-10-01

In this study, silver sulfide nanoworms were prepared via a rapid microwave-assisted hydrothermal method by reacting silver nitrate and thioacetamide in the aqueous solution of the Bovine Serum Albumin (BSA) protein. The morphology, composition, and crystallinity of the nanoworms were characterized by field emission scanning electron microscopy (FESEM), X-ray powder diffraction (XRD), transmission electron microscopy (TEM), selected area electron diffraction (SAED), X-ray energy dispersive spectroscopy (EDS), and Fourier transform infrared (FTIR) spectroscopy. The results show that the nanoworms were assembled by multiple adjacent Ag2S nanoparticles and stabilized by a layer of BSA attached to their surface. The nanoworms have the sizes of about 50 nm in diameter and hundreds of nanometers in length. The analyses of high-resolution TEM and their correlative Fast Fourier Transform (FFT) indicate that the adjacent Ag2S nanoparticles grow by misoriented attachment at the connective interfaces to form the nanoworm structure. In vitro assays on the human cervical cancer cell line HeLa show that the nanoworms exhibit good biocompatibility due to the presence of BSA coating. This combination of features makes the nanoworms attractive and promising building blocks for advanced materials and devices.

Structural and morphological peculiarities of hybrid Au/nanodiamond engineered nanostructures

NASA Astrophysics Data System (ADS)

Matassa, Roberto; Orlanducci, Silvia; Reina, Giacomo; Cassani, Maria Cristina; Passeri, Daniele; Terranova, Maria Letizia; Rossi, Marco

2016-08-01

Nanostructured Au nano-platelets have been synthesized from an Au(III) complex by growth process triggered by nanodiamond (ND). An electroless synthetic route has been used to obtain 2D Au/ND architectures, where individual nanodiamond particles are intimately embedded into face-centered cubic Au platelets. The combined use of high resolution transmission electron microscopy (HR-TEM) and selected area electron diffraction (SAED), was able to reveal the unusual organization of these hybrid nanoparticles, ascertaining the existence of preferential crystallographic orientations for both nanocrystalline species and highlighting their mutual locations. Detailed information on the sample microstructure have been gathered by fast Fourier transform (FFT) and inverse fast Fourier transform (IFFT) of HR-TEM images, allowing us to figure out the role of Au defects, able to anchor ND crystallites and to provide specific sites for heteroepitaxial Au growth. Aggregates constituted by coupled ND and Au, represent interesting systems conjugating the best optoelectronics and plasmonics properties of the two different materials. In order to promote realistically the applications of such outstanding Au/ND materials, the cooperative mechanisms at the basis of material synthesis and their influence on the details of the hybrid nanostructures have to be deeply understood.

Structural and morphological peculiarities of hybrid Au/nanodiamond engineered nanostructures

PubMed Central

Matassa, Roberto; Orlanducci, Silvia; Reina, Giacomo; Cassani, Maria Cristina; Passeri, Daniele; Terranova, Maria Letizia; Rossi, Marco

2016-01-01

Nanostructured Au nano-platelets have been synthesized from an Au(III) complex by growth process triggered by nanodiamond (ND). An electroless synthetic route has been used to obtain 2D Au/ND architectures, where individual nanodiamond particles are intimately embedded into face-centered cubic Au platelets. The combined use of high resolution transmission electron microscopy (HR-TEM) and selected area electron diffraction (SAED), was able to reveal the unusual organization of these hybrid nanoparticles, ascertaining the existence of preferential crystallographic orientations for both nanocrystalline species and highlighting their mutual locations. Detailed information on the sample microstructure have been gathered by fast Fourier transform (FFT) and inverse fast Fourier transform (IFFT) of HR-TEM images, allowing us to figure out the role of Au defects, able to anchor ND crystallites and to provide specific sites for heteroepitaxial Au growth. Aggregates constituted by coupled ND and Au, represent interesting systems conjugating the best optoelectronics and plasmonics properties of the two different materials. In order to promote realistically the applications of such outstanding Au/ND materials, the cooperative mechanisms at the basis of material synthesis and their influence on the details of the hybrid nanostructures have to be deeply understood. PMID:27514638

Laryngeal teflonoma identified by Fourier-transform infrared microspectroscopy after forensic autopsy: an interesting tool for foreign material identification in forensic cases.

PubMed

Duband, Sébastien; Govin, Alexandre; Dumollard, Jean-Marc; Forest, Fabien; Basset, Thierry; Péoc'h, Michel

2012-01-10

Forensic pathologists are sometimes confronted with microscopic foreign bodies mixed in with soft tissues surrounding wounds and which are thus difficult to identify. This identification, however, could be primordial in investigating a crime and in determining the weapon used. A case of a fatal respiratory distress syndrome due to conjoining suicidal drug intoxication and laryngeal obstruction by a voluminous foreign body giant cell granuloma is presented. The classical histological examination showed exogenous particles in the vocal cord tumor with birefringent qualities. Their analysis with Fourier-Transform infrared (FTIR) spectrometry coupled with infrared microscope allows the determination of their chemical nature as polytetrafluoroethylene and to the diagnosis of teflonoma. This case report put the emphasis on the forensic interest of the FTIR imaging. Copyright © 2011 Elsevier Ireland Ltd. All rights reserved.

Improvements in low-cost label-free QPI microscope for live cell imaging

NASA Astrophysics Data System (ADS)

Seniya, C.; Towers, C. E.; Towers, D. P.

2017-07-01

This paper reports an improvement in the development of a low-cost QPI microscope offering new capabilities in term of phase measurement accuracy for label-free live samples in the longer term (i.e., hours to days). The spatially separated scattered and non-scattered image light fields are reshaped in the Fourier plane and modulated to form an interference image at a CCD camera. The apertures that enable these two beams to be generated have been optimised by means of laser-cut apertures placed on the mirrors of a Michelson interferometer and has improved the phase measuring and reconstruction capability of the QPI microscope. The microscope was tested with transparent onion cells as an object of interest.

Comprehensive study of unexpected microscope condensers formed in sample arrangements commonly used in optical microscopy.

PubMed

Desai, Darshan B; Aldawsari, Mabkhoot Mudith S; Alharbi, Bandar Mohammed H; Sen, Sanchari; Grave de Peralta, Luis

2015-09-01

We show that various setups for optical microscopy which are commonly used in biomedical laboratories behave like efficient microscope condensers that are responsible for observed subwavelength resolution. We present a series of experiments and simulations that reveal how inclined illumination from such unexpected condensers occurs when the sample is perpendicularly illuminated by a microscope's built-in white-light source. In addition, we demonstrate an inexpensive add-on optical module that serves as an efficient and lightweight microscope condenser. Using such add-on optical module in combination with a low-numerical-aperture objective lens and Fourier plane imaging microscopy technique, we demonstrate detection of photonic crystals with a period nearly eight times smaller than the Rayleigh resolution limit.

Microscopy illumination engineering using a low-cost liquid crystal display.

PubMed

Guo, Kaikai; Bian, Zichao; Dong, Siyuan; Nanda, Pariksheet; Wang, Ying Min; Zheng, Guoan

2015-02-01

Illumination engineering is critical for obtaining high-resolution, high-quality images in microscope settings. In a typical microscope, the condenser lens provides sample illumination that is uniform and free from glare. The associated condenser diaphragm can be manually adjusted to obtain the optimal illumination numerical aperture. In this paper, we report a programmable condenser lens for active illumination control. In our prototype setup, we used a $15 liquid crystal display as a transparent spatial light modulator and placed it at the back focal plane of the condenser lens. By setting different binary patterns on the display, we can actively control the illumination and the spatial coherence of the microscope platform. We demonstrated the use of such a simple scheme for multimodal imaging, including bright-field microscopy, darkfield microscopy, phase-contrast microscopy, polarization microscopy, 3D tomographic imaging, and super-resolution Fourier ptychographic imaging. The reported illumination engineering scheme is cost-effective and compatible with most existing platforms. It enables a turnkey solution with high flexibility for researchers in various communities. From the engineering point-of-view, the reported illumination scheme may also provide new insights for the development of multimodal microscopy and Fourier ptychographic imaging.

Evaluation of the microscopic distribution of florfenicol in feed pellets for salmon by Fourier Transform infrared imaging and multivariate analysis.

PubMed

Bastidas, Camila Y; von Plessing, Carlos; Troncoso, José; Del P Castillo, Rosario

2018-04-15

Fourier Transform infrared imaging and multivariate analysis were used to identify, at the microscopic level, the presence of florfenicol (FF), a heavily-used antibiotic in the salmon industry, supplied to fishes in feed pellets for the treatment of salmonid rickettsial septicemia (SRS). The FF distribution was evaluated using Principal Component Analysis (PCA) and Augmented Multivariate Curve Resolution with Alternating Least Squares (augmented MCR-ALS) on the spectra obtained from images with pixel sizes of 6.25 μm × 6.25 μm and 1.56 μm × 1.56 μm, in different zones of feed pellets. Since the concentration of the drug was 3.44 mg FF/g pellet, this is the first report showing the powerful ability of the used of spectroscopic techniques and multivariate analysis, especially the augmented MCR-ALS, to describe the FF distribution in both the surface and inner parts of feed pellets at low concentration, in a complex matrix and at the microscopic level. The results allow monitoring the incorporation of the drug into the feed pellets. Copyright © 2018 Elsevier B.V. All rights reserved.

Nucleation and Growth of Crystalline Grains in RF-Sputtered TiO 2 Films

DOE PAGES

Johnson, J. C.; Ahrenkiel, S. P.; Dutta, P.; ...

2009-01-01

Amore » morphous TiO 2 thin films were radio frequency sputtered onto siliconmonoxide and carbon support films on molybdenum transmission electron microscope (TEM) grids and observed during in situ annealing in a TEM heating stage at 250 ∘ C. The evolution of crystallization is consistent with a classical model of homogeneous nucleation and isotropic grain growth. The two-dimensional grain morphology of the TEM foil allowed straightforward recognition of amorphous and crystallized regions of the films, for measurement of crystalline volume fraction and grain number density. By assuming that the kinetic parameters remain constant beyond the onset of crystallization, the final average grain size was computed, using an analytical extrapolation to the fully crystallized state. Electron diffraction reveals a predominance of the anatase crystallographic phase.« less

Iridovirus infections in farm-reared tropical ornamental fish.

PubMed

Paperna, I; Vilenkin, M; de Matos, A P

2001-12-20

A systemic viral infection in both gourami Trichogaster spp. and swordtail Xiphophorus hellerii and an outbreak of lymphocystis in scalare Pterophyllum scalarae and gourami are reported to have occurred in fish reared in ornamental fish farms in Israel. The systemic infection developed in endothelial cells that became hypertrophic and their contents were modified. The presence of such cells in light-microscopically examined stained smears and sections provides an initial indication for this systemic viral infection. Infection in gourami caused hemorrhagic dropsy. Transmission electron microscopic (TEM) images of iridovirus-like particles recovered from gouramies showed them to be 138 to 201 nm from vertex to vertex (v-v); those from swordtails were 170 to 188 nm v-v. TEM images of lymphocystis virions from scalare were 312 to 342 nm v-v and from gourami 292 to 341 nm v-v. Lymphocystis cells from the gourami were joined by a solid hyaline plate, which was lacking in the infection in scalare where the intercellular spaces between the lymphocystis cells consisted of loose connective tissue.

Microstructural Study of Micron-Sized Craters Simulating Stardust Impacts in Aluminum 1100 Targets

NASA Technical Reports Server (NTRS)

Leroux, Hugues; Borg, Janet; Troadec, David; Djouadi, Zahia; Horz, Friedrich

2006-01-01

Various microscopic techniques were used to characterize experimental micro- craters in aluminium foils to prepare for the comprehensive analysis of the cometary and interstellar particle impacts in aluminium foils to be returned by the Stardust mission. First, SEM (Scanning Electron Microscopy) and EDS (Energy Dispersive X-ray Spectroscopy) were used to study the morphology of the impact craters and the bulk composition of the residues left by soda-lime glass impactors. A more detailed structural and compositional study of impactor remnants was then performed using TEM (Transmission Electron Microscopy), EDS, and electron diffraction methods. The TEM samples were prepared by Focused Ion Beam (FIB) methods. This technique proved to be especially valuable in studying impact crater residues and impact crater morphology. Finally, we also showed that InfraRed microscopy (IR) can be a quick and reliable tool for such investigations. The combination of all of these tools enables a complete microscopic characterization of the craters.

An ultrastructural study on corkscrew hairs and cigarette-ash-shaped hairs observed by dermoscopy of tinea capitis.

PubMed

Lu, Mao; Ran, Yuping; Dai, Yaling; Lei, Song; Zhang, Chaoliang; Zhuang, Kaiwen; Hu, Wenying

2016-01-01

This study was aimed to explain the formation mechanisms of corkscrew hairs and cigarette-ash-shaped hairs observed by dermoscopy of tinea capitis. In the present work, the ultrastructure of the involved hairs collected from a girl with tinea capitis caused by Trichophyton violaceum was observed by scanning electron microscope (SEM) and transmission electron microscope (TEM). SEM observation of the corkscrew hair revealed bent hair shaft and asymmetrically disrupted cuticle layer. TEM findings demonstrated the hair shaft became weak. The corkscrew hairs closely covered by scales on the scalp were observed under dermoscopy. We speculate that the formation of corkscrew hairs is a result of a combination of internal damage due to hair degradation by T. violaceum and external resistance due to scales covering the hair. SEM observation of the cigarette-ash-shaped hair revealed irregularly disrupted and incompact end, which might represent the stump of the broken corkscrew hair after treatment. © Wiley Periodicals, Inc.

Morphological and Microstructural Evolution of Phosphorous-Rich Layer in SnAgCu/Ni-P UBM Solder Joint

NASA Astrophysics Data System (ADS)

Lin, Yung-Chi; Shih, Toung-Yi; Tien, Shih-Kang; Duh, Jenq-Gong

2007-11-01

Interfacial morphologies and microstructure of Sn-3Ag-0.5Cu/Ni-P under bump metallization (UBM) with various phosphorous contents were investigated by transmission electron microscope (TEM) and field emission electron probe microanalyzer (FE-EPMA). It was revealed that as the Ni-Sn-P compound was formed between the solder matrix and Ni-P UBM, the conventionally so-called phosphorous-rich (P-rich) layer was transformed to a series of layer compounds, including Ni3P, Ni12P5 and Ni2P. The relationship between Ni-Sn-P formation and evolution of P-rich layers was probed by electron microscopic characterization with the aid of the phase diagram of Ni-P. On the basis of the TEM micrograph, the selected area diffraction (SAD) pattern, and the FE-EPMA results, the detailed phase evolution of P-rich layers in the SnAgCu/Ni-P joint was revealed and proposed.

The preparation of nanosized polyethylene particles via novel heterogeneous non-metallocene catalyst (m-CH3PhO)TiCl3/CNTs/AlEt3

NASA Astrophysics Data System (ADS)

Wang, J.; Guo, J. P.; Yi, J. J.; Huang, Q. G.; Li, H. M.; Li, Y. F.; Gao, K. J.; Yang, W. T.

2014-08-01

This paper reports the preparation of coral-shaped topological morphology nascent polyethylene (PE) particles promoted by the novel heterogeneous non-metallocene catalyst (m-CH3PhO)TiCl3/carbon nanotubes (CNTs), with AlEt3 used as a cocatalyst. Scanning electron microscope (SEM), high resolution transmission electron microscope (HR-TEM) and inductively coupled plasma (ICP) emission spectroscopy were used to determine the morphology of the catalyst particles and the content of (m-CH3PhO)TiCl3. The carbon nanotube surface was treated with Grignard Reagent prior to reacting with (m-CH3PhO)TiCl3. The catalyst system could effectively catalyze ethylene polymerization and ethylene with 1- hexene copolymerization, the catalytic activity could reach up to 5.8 kg/((gTi)h). Morphology of the obtained polymer particles by SEM and HR-TEM technique revealed that the nascent polyethylene particles looked like coral shape in micro-size. The multiwalled carbon nanotubes (MWCNTs) supported catalysts polymerized ethylene to form polymer nanocomposite in situ. The microscopic examination of this nanocomposite revealed that carbon nanoparticles in PE matrix had a good distribution and the cryogenically fractured surface was ductile-like when polymerization time was 2 min.

Electron microscopic visualization of complementary labeled DNA with platinum-containing guanine derivative.

PubMed

Loukanov, Alexandre; Filipov, Chavdar; Mladenova, Polina; Toshev, Svetlin; Emin, Saim

2016-04-01

The object of the present report is to provide a method for a visualization of DNA in TEM by complementary labeling of cytosine with guanine derivative, which contains platinum as contrast-enhanced heavy element. The stretched single-chain DNA was obtained by modifying double-stranded DNA. The labeling method comprises the following steps: (i) stretching and adsorption of DNA on the support film of an electron microscope grid (the hydrophobic carbon film holding negative charged DNA); (ii) complementary labeling of the cytosine bases from the stretched single-stranded DNA pieces on the support film with platinum containing guanine derivative to form base-specific hydrogen bond; and (iii) producing a magnified image of the base-specific labeled DNA. Stretched single-stranded DNA on a support film is obtained by a rapid elongation of DNA pieces on the surface between air and aqueous buffer solution. The attached platinum-containing guanine derivative serves as a high-dense marker and it can be discriminated from the surrounding background of support carbon film and visualized by use of conventional TEM observation at 100 kV accelerated voltage. This method allows examination of specific nucleic macromolecules through atom-by-atom analysis and it is promising way toward future DNA-sequencing or molecular diagnostics of nucleic acids by electron microscopic observation. © 2016 Wiley Periodicals, Inc.

Distinction between amorphous and healed planar deformation features in shocked quartz using composite color scanning electron microscope cathodoluminescence (SEM-CL) imaging

NASA Astrophysics Data System (ADS)

Hamers, Maartje F.; Pennock, Gill M.; Herwegh, Marco; Drury, Martyn R.

2016-10-01

Planar deformation features (PDFs) in quartz are one of the most reliable and most widely used forms of evidence for hypervelocity impact. PDFs can be identified in scanning electron microscope cathodoluminescence (SEM-CL) images, but not all PDFs show the same CL behavior: there are nonluminescent and red luminescent PDFs. This study aims to explain the origin of the different CL emissions in PDFs. Focused ion beam (FIB) thin foils were prepared of specific sample locations selected in composite color SEM-CL images and were analyzed in a transmission electron microscope (TEM). The FIB preparation technique allowed a direct, often one-to-one correlation between the CL images and the defect structure observed in TEM. This correlation shows that composite color SEM-CL imaging allows distinction between amorphous PDFs on one hand and healed PDFs and basal Brazil twins on the other: nonluminescent PDFs are amorphous, while healed PDFs and basal Brazil twins are red luminescent, with a dominant emission peak at 650 nm. We suggest that the red luminescence is the result of preferential beam damage along dislocations, fluid inclusions, and twin boundaries. Furthermore, a high-pressure phase (possibly stishovite) in PDFs can be detected in color SEM-CL images by its blue luminescence.

STEM-HAADF electron microscopy analysis of the central dark line defect of human tooth enamel crystallites.

PubMed

Gasga, Jose Reyes; Carbajal-de-la-Torre, Georgina; Bres, Etienne; Gil-Chavarria, Ivet M; Rodríguez-Hernández, Ana G; Garcia-Garcia, Ramiro

2008-02-01

When human tooth enamel is observed with the Transmission Electron Microscope (TEM), a structural defect is registered in the central region of their nanometric grains or crystallites. This defect has been named as Central Dark Line (CDL) and its structure and function in the enamel structure have been unknown yet. In this work we present the TEM analysis to these crystallites using the High Angle Annular Dark Field (HAADF) technique. Our results suggest that the CDL region is the calcium richest part of the human tooth enamel crystallites.

Atomic-Scale Insights into the Oxidation of Aluminum.

PubMed

Nguyen, Lan; Hashimoto, Teruo; Zakharov, Dmitri N; Stach, Eric A; Rooney, Aidan P; Berkels, Benjamin; Thompson, George E; Haigh, Sarah J; Burnett, Tim L

2018-01-24

The surface oxidation of aluminum is still poorly understood despite its vital role as an insulator in electronics, in aluminum-air batteries, and in protecting the metal against corrosion. Here we use atomic resolution imaging in an environmental transmission electron microscope (TEM) to investigate the mechanism of aluminum oxide formation. Harnessing electron beam sputtering we prepare a pristine, oxide-free metal surface in the TEM. This allows us to study, as a function of crystallographic orientation and oxygen gas pressure, the full oxide growth regime from the first oxide nucleation to a complete saturated, few-nanometers-thick surface film.

Measurement of the Elastic Modulus of a Single Boron Nitride Nanotube

NASA Astrophysics Data System (ADS)

Chopra, Nasreen G.; Cohen, Marvin L.; Louie, Steven G.; Zettl, A.

1997-03-01

In situ transmission electron microscope (TEM) measurements of thermally-excited vibrational characteristics of boron nitride (BN) nanotubes are used to extract the elastic modulus. We find BN nanotubes to have a higher axial Young's modulus, 1.2 TPa, than any other insulating fiber. This value is consistent with theoretical predictions and confirms previous TEM observations of the high degree of crystallinity of these structures. This work was supported by the U. S. Department of Energy under contract No. DE-AC03-76-SF00098 and the Office of Naval Research, Order No. N00014-95-F-0099

Atomic-Scale Insights into the Oxidation of Aluminum

DOE PAGES

Nguyen, Lan; Hashimoto, Teruo; Zakharov, Dmitri N.; ...

2018-01-10

Here, the surface oxidation of aluminum is still poorly understood despite its vital role as an insulator in electronics, in aluminum–air batteries, and in protecting the metal against corrosion. Here we use atomic resolution imaging in an environmental transmission electron microscope (TEM) to investigate the mechanism of aluminum oxide formation. Harnessing electron beam sputtering we prepare a pristine, oxide-free metal surface in the TEM. This allows us to study, as a function of crystallographic orientation and oxygen gas pressure, the full oxide growth regime from the first oxide nucleation to a complete anometers-thick surface film.

Fourier Transform Infrared Spectroscopy Part III. Applications.

ERIC Educational Resources Information Center

Perkins, W. D.

1987-01-01

Discusses the use of the FT-IR spectrometer in analyses that were previously avoided. Examines some of the applications of this spectroscopy with aqueous solutions, circular internal reflection, samples with low transmission, diffuse reflectance, infrared emission, and the infrared microscope. (TW)

Electron microscopic diagnosis of human flavivirus encephalitis: use of confocal microscopy as an aid.

PubMed

Chu, C T; Howell, D N; Morgenlander, J C; Hulette, C M; McLendon, R E; Miller, S E

1999-10-01

The distinction between intracranial viral infections and inflammatory conditions requiring immunosuppression is important. Although specific laboratory reagents are readily available for some viruses, diagnosis of arbovirus infection is more difficult. Transmission electron microscopy (TEM) theoretically allows identification of viral particles independent of reagent availability, but it has limited sensitivity. We report two cases of human flavivirus encephalitis diagnosed by TEM. Laser scanning confocal microscopy (LSCM) was used in one case to survey unembedded tissue slices for focal abnormalities, from which fragments smaller than 1 mm2 were excised for epoxy embedding. This facilitated TEM identification of intracytoplasmic, budding, 35-40 nm spherical virus particles, confirmed by serology as St. Louis encephalitis. In contrast to mosquitoes and newborn mice, in which high viral loads are associated with minimal tissue responses, these biopsies showed florid angiodestructive inflammation and microgliosis, with rare virions in necrotic perivascular cells and astrocytes. To our knowledge, this represents the first ultrastructural study of St. Louis encephalitis in humans, indicating the potential value of LSCM-aided TEM.

TEM in situ micropillar compression tests of ion irradiated oxide dispersion strengthened alloy

NASA Astrophysics Data System (ADS)

Yano, K. H.; Swenson, M. J.; Wu, Y.; Wharry, J. P.

2017-01-01

The growing role of charged particle irradiation in the evaluation of nuclear reactor candidate materials requires the development of novel methods to assess mechanical properties in near-surface irradiation damage layers just a few micrometers thick. In situ transmission electron microscopic (TEM) mechanical testing is one such promising method. In this work, microcompression pillars are fabricated from a Fe2+ ion irradiated bulk specimen of a model Fe-9%Cr oxide dispersion strengthened (ODS) alloy. Yield strengths measured directly from TEM in situ compression tests are within expected values, and are consistent with predictions based on the irradiated microstructure. Measured elastic modulus values, once adjusted for the amount of deformation and deflection in the base material, are also within the expected range. A pillar size effect is only observed in samples with minimum dimension ≤100 nm due to the low inter-obstacle spacing in the as received and irradiated material. TEM in situ micropillar compression tests hold great promise for quantitatively determining mechanical properties of shallow ion-irradiated layers.

Artifacts introduced by ion milling in Al-Li-Cu alloys.

PubMed

Singh, A K; Imam, M A; Sadananda, K

1988-04-01

Ion milling is commonly used to prepare specimens for observation under transmission electron microscope (TEM). This technique sometimes introduces artifacts in specimens contributing to misleading interpretation of TEM results as observed in the present investigation of Al-Li-Cu alloys. This type of alloy, in general, contains several kinds of precipitates, namely delta', T1, and theta'. It is found that ion milling even for a short time produces drastic changes in the precipitate characteristics as compared to standard electropolishing methods of specimen preparation for TEM. Careful analysis of selected area diffraction patterns and micrographs shows that after ion milling delta' precipitates are very irregular, whereas other precipitates coarsen and they are surrounded by misfit dislocations. In situ hot-stage TEM experiments were performed to relate the microstructure to that observed in the ion-milled specimen. Results and causes of ion milling effects on the microstructure are discussed in relation to standard electropolishing techniques and in situ hot-stage experiment.

Transmission electron microscope studies of extraterrestrial materials

NASA Technical Reports Server (NTRS)

Keller, Lindsay P.

1995-01-01

Transmission Electron Microscopy, X-Ray spectrometry and electron-energy-loss spectroscopy are used to analyse carbon in interplanetary dust particles. Optical micrographs are shown depicting cross sections of the dust particles embedded in sulphur. Selected-area electron diffraction patterns are shown. Transmission Electron Microscope specimens of lunar soil were prepared using two methods: ion-milling and ultramicrotomy. A combination of high resolution TEM imaging and electron diffraction is used to characterize the opaque assemblages. The opaque assemblages analyzed in this study are dominated by ilmenite with lesser rutile and spinel exsolutions, and traces of Fe metal.

One-dimensional nanoferroic rods; synthesis and characterization

NASA Astrophysics Data System (ADS)

Ahmed, M. A.; Seddik, U.; Okasha, N.; Imam, N. G.

2015-11-01

One-dimensional nanoferroic rods of BaTiO3 were synthesized by improved citrate auto-combustion technology using tetrabutyl titanate. X-ray diffraction (XRD), scanning electron microscopy (SEM), energy-dispersive X-ray (EDX), transmission electron microscopy (TEM), atomic force microscopy (AFM) and Fourier transform infrared spectroscopy (FTIR) have been used to characterize the prepared sample. The results indicated that the crystal structure of BaTiO3 is tetragonal phase with an average crystallite size of 47 nm. SEM image gives a cauliflower-like morphology of the agglomerated nanorods. The stoichiometry of the chemical composition of the BaTiO3 ceramic was confirmed by EDX. TEM micrograph exhibited that BaTiO3 nanoparticles have rod-like shape with an average length of 120 nm and width of 43 nm. AFM was used to investigate the surface topography and its roughness. The topography image in 3D showed that the BaTiO3 particles have a rod shape with an average particle size of 116 nm which in agreement with 3D TEM result.

TEM in situ cube-corner indentation analysis using ViBe motion detection algorithm

NASA Astrophysics Data System (ADS)

Yano, K. H.; Thomas, S.; Swenson, M. J.; Lu, Y.; Wharry, J. P.

2018-04-01

Transmission electron microscopic (TEM) in situ mechanical testing is a promising method for understanding plasticity in shallow ion irradiated layers and other volume-limited materials. One of the simplest TEM in situ experiments is cube-corner indentation of a lamella, but the subsequent analysis and interpretation of the experiment is challenging, especially in engineering materials with complex microstructures. In this work, we: (a) develop MicroViBE, a motion detection and background subtraction-based post-processing approach, and (b) demonstrate the ability of MicroViBe, in combination with post-mortem TEM imaging, to carry out an unbiased qualitative interpretation of TEM indentation videos. We focus this work around a Fe-9%Cr oxide dispersion strengthened (ODS) alloy, irradiated with Fe2+ ions to 3 dpa at 500 °C. MicroViBe identifies changes in Laue contrast that are induced by the indentation; these changes accumulate throughout the mechanical loading to generate a "heatmap" of features in the original TEM video that change the most during the loading. Dislocation loops with b = ½ <111> identified by post-mortem scanning TEM (STEM) imaging correspond to hotspots on the heatmap, whereas positions of dislocation loops with b = <100> do not correspond to hotspots. Further, MicroViBe enables consistent, objective quantitative approximation of the b = ½ <111> dislocation loop number density.

Synthesis and luminescence properties of Sm3+ doped CaTiO3 nanophosphor for application in white LED under NUV excitation.

PubMed

Shivaram, M; Nagabhushana, H; Sharma, S C; Prashantha, S C; Daruka Prasad, B; Dhananjaya, N; Hari Krishna, R; Nagabhushana, B M; Shivakumara, C; Chakradhar, R P S

2014-07-15

CaTiO3:Sm(3+) (1-11 mol%) nanophosphors were successfully synthesized by a low temperature solution combustion method [LCS]. The structural and morphological properties of the phosphors were studied by using Powder X-ray diffractometer (PXRD), Fourier transform infrared (FTIR), X-ray photo electron spectroscopy (XPS), scanning electron microscope (SEM) and transmission electron microscopy (TEM). TEM studies indicate that the size of the phosphor is ∼20-35 nm. Photoluminescence (PL) properties of Sm(3+) (1-11 mol%) doped CaTiO3 for NUV excitation (407 nm) was studied in order to investigate the possibility of its use in White light emitting diode (WLED) applications. The emission spectra consists of intra 4f transitions of Sm(3+), such as (4)G5/2→(6)H5/2 (561 nm), (4)G5/2→(6)H7/2 (601-611 nm), (4)G5/2→(6)H9/2 (648 nm) and (4)G5/2→(6)H11/2 (703 nm) respectively. Further, the emission at 601-611 nm show strong orange-red emission and can be applied to the orange-red emission of phosphor for the application for near ultra violet (NUV) excitation. Thermoluminescence (TL) of the samples irradiated with gamma source in the dose range 100-500 Gy was recorded at a heating rate of 5°Cs(-1). Two well resolved glow peaks at 164°C and 214°C along with shouldered peak at 186°C were recorded. TL intensity increases up to 300 Gy and thereafter, it decreases with further increase of dose. The kinetic parameters namely activation energy (E), frequency factor (s) and order of kinetics were estimated and results were discussed in detail. Copyright © 2014 Elsevier B.V. All rights reserved.

Unveiling Clues from Spacecraft Missions to Comets and Asteroids through Impact Experiments

NASA Technical Reports Server (NTRS)

Lederer, Susan M.; Jensen, Elizabeth; Fane, Michael; Smith, Douglas; Holmes, Jacob; Keller, Lindasy P.; Lindsay, Sean S.; Wooden, Diane H.; Whizin, Akbar; Cintala, Mark J.;

Line-width roughness of advanced semiconductor features by using FIB and planar-TEM as reference metrology

NASA Astrophysics Data System (ADS)

Takamasu, Kiyoshi; Takahashi, Satoru; Kawada, Hiroki; Ikota, Masami

2018-03-01

LER (Line Edge Roughness) and LWR (Line Width Roughness) of the semiconductor device are an important evaluation scale of the performance of the device. Conventionally, LER and LWR is evaluated from CD-SEM (Critical Dimension Scanning Electron Microscope) images. However, CD-SEM measurement has a problem that high frequency random noise is large, and resolution is not sufficiently high. For random noise of CD-SEM measurement, some techniques are proposed. In these methods, it is necessary to set parameters for model and processing, and it is necessary to verify the correctness of these parameters using reference metrology. We have already proposed a novel reference metrology using FIB (Focused Ion Beam) process and planar-TEM (Transmission Electron Microscope) method. In this study, we applied the proposed method to three new samples such as SAQP (Self-Aligned Quadruple Patterning) FinFET device, EUV (Extreme Ultraviolet Lithography) conventional resist, and EUV new material resist. LWR and PSD (Power Spectral Density) of LWR are calculated from the edge positions on planar-TEM images. We confirmed that LWR and PSD of LWR can be measured with high accuracy and evaluated the difference by the proposed method. Furthermore, from comparisons with PSD of the same sample by CD-SEM, the validity of measurement of PSD and LWR by CD-SEM can be verified.

Focused ion beam (FIB)/scanning electron microscopy (SEM) in tissue structural research.

PubMed

Leser, Vladka; Milani, Marziale; Tatti, Francesco; Tkalec, Ziva Pipan; Strus, Jasna; Drobne, Damjana

2010-10-01

The focused ion beam (FIB) and scanning electron microscope (SEM) are commonly used in material sciences for imaging and analysis of materials. Over the last decade, the combined FIB/SEM system has proven to be also applicable in the life sciences. We have examined the potential of the focused ion beam/scanning electron microscope system for the investigation of biological tissues of the model organism Porcellio scaber (Crustacea: Isopoda). Tissue from digestive glands was prepared as for conventional SEM or as for transmission electron microscopy (TEM). The samples were transferred into FIB/SEM for FIB milling and an imaging operation. FIB-milled regions were secondary electron imaged, back-scattered electron imaged, or energy dispersive X-ray (EDX) analyzed. Our results demonstrated that FIB/SEM enables simultaneous investigation of sample gross morphology, cell surface characteristics, and subsurface structures. The same FIB-exposed regions were analyzed by EDX to provide basic compositional data. When samples were prepared as for TEM, the information obtained with FIB/SEM is comparable, though at limited magnification, to that obtained from TEM. A combination of imaging, micro-manipulation, and compositional analysis appears of particular interest in the investigation of epithelial tissues, which are subjected to various endogenous and exogenous conditions affecting their structure and function. The FIB/SEM is a promising tool for an overall examination of epithelial tissue under normal, stressed, or pathological conditions.

3D-profile measurement of advanced semiconductor features by using FIB as reference metrology

NASA Astrophysics Data System (ADS)

Takamasu, Kiyoshi; Iwaki, Yuuki; Takahashi, Satoru; Kawada, Hiroki; Ikota, Masami

2017-03-01

A novel method of sub-nanometer uncertainty for the 3D-profile measurement and LWR (Line Width Roughness) measurement by using FIB (Focused Ion Beam) processing, and TEM (Transmission Electron Microscope) and CD-SEM (Critical Dimension Scanning Electron Microscope) images measurement is proposed to standardize 3D-profile measurement through reference metrology. In this article, we apply the methodology to line profile measurements and roughness measurement of advanced FinFET (Fin-shaped Field-Effect Transistor) features. The FinFET features are horizontally sliced as a thin specimen by FIB micro sampling system. Horizontally images of the specimens are obtained then by a planar TEM. LWR is calculated from the edges positions on TEM images. Moreover, we already have demonstrated the novel on-wafer 3D-profile metrology as "FIB-to-CDSEM method" with FIB slope cut and CD-SEM measuring. Using the method, a few micrometers wide on a wafer is coated and cut by 45-degree slope using FIB tool. Then, the wafer is transferred to CD-SEM to measure the cross section image by top down CD-SEM measurement. We applied FIB-to-CDSEM method to a CMOS image sensor feature. The 45-degree slope cut surface is observed using AFM. The surface profile of slope cut surface and line profiles are analyzed for improving the accuracy of FIB-to-CDSEM method.

Size controlled biogenic silver nanoparticles as antibacterial agent against isolates from HIV infected patients

NASA Astrophysics Data System (ADS)

Suganya, K. S. Uma; Govindaraju, K.; Kumar, V. Ganesh; Dhas, T. Stalin; Karthick, V.; Singaravelu, G.; Elanchezhiyan, M.

2015-06-01

Silver nanoparticles (AgNPs) are synthesized using biological sources due to its high specificity in biomedical applications. Herein, we report the size and shape controlled synthesis of AgNPs using the aqueous extract of blue green alga, Spirulina platensis. Size, shape and elemental composition of AgNPs were characterized using UV-vis spectroscopy, Fluorescence spectroscopy, FT-IR (Fourier Transform-Infrared Spectroscopy), FT-RS (Fourier Transform-Raman Spectroscopy), SEM-EDAX (Scanning Electron Microscopy-Energy Dispersive X-ray analysis) and HR-TEM (High Resolution Transmission Electron Microscopy). AgNPs were stable, well defined and monodispersed (spherical) with an average size of 6 nm. The synthesized AgNPs were tested for its antibacterial potency against isolates obtained from HIV patients.

Transmission Electron Microscope Observations of Phyllosilicate Development During Experimental Aqueous Alteration of Allende

NASA Technical Reports Server (NTRS)

Jones, C. L.; Brearley, A. J.

2000-01-01

Samples of Allende have been altered hydrothermally under oxidizing conditions at 200 C. TEM studies show that within 30 days evidence of replacement of matrix olivines by fine-grained serpentine is present and by 90 days complete alteration of many grains has occurred.

eV-TEM: Transmission electron microscopy in a low energy cathode lens instrument.

PubMed

Geelen, Daniël; Thete, Aniket; Schaff, Oliver; Kaiser, Alexander; van der Molen, Sense Jan; Tromp, Rudolf

2015-12-01

We are developing a transmission electron microscope that operates at extremely low electron energies, 0-40 eV. We call this technique eV-TEM. Its feasibility is based on the fact that at very low electron energies the number of energy loss pathways decreases. Hence, the electron inelastic mean free path increases dramatically. eV-TEM will enable us to study elastic and inelastic interactions of electrons with thin samples. With the recent development of aberration correction in cathode lens instruments, a spatial resolution of a few nm appears within range, even for these very low electron energies. Such resolution will be highly relevant to study biological samples such as proteins and cell membranes. The low electron energies minimize adverse effects due to radiation damage. Copyright © 2015. Published by Elsevier B.V.

Excitation of propagating surface plasmons with a scanning tunnelling microscope.

PubMed

Wang, T; Boer-Duchemin, E; Zhang, Y; Comtet, G; Dujardin, G

2011-04-29

Inelastic electron tunnelling excitation of propagating surface plasmon polaritons (SPPs) on a thin gold film is demonstrated. This is done by combining a scanning tunnelling microscope (STM) with an inverted optical microscope. Analysis of the leakage radiation in both the image and Fourier planes unambiguously shows that the majority (up to 99.5%) of the detected photons originate from propagating SPPs with propagation lengths of the order of 10  µm. The remaining photon emission is localized under the STM tip and is attributed to a tip-gold film coupled plasmon resonance as evidenced by the bimodal spectral distribution and enhanced emission intensity observed using a silver STM tip for excitation.

Electron microscopic visualization of autophagosomes induced by infection of human papillomavirus pseudovirions

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

Ishii, Yoshiyuki, E-mail: yishii@nih.go.jp

2013-04-19

Highlights: •HPV16 pseudovirions (16PsVs) infection induces an autophagy response. •The autophagy was analyzed by transmission electron microscope (TEM). •TEM showed the double-membrane vesicles in HeLa cells inoculated with 16PsVs. •These vesicles incorporated 16PsVs particles in the lumen. •These results imply that autophagosomes are generated from the plasma membrane. -- Abstract: Autophagy is a bulk degradation process for subcellular proteins and organelles to manage cell starvation. Autophagy is associated with the formation of autophagosomes and further functions as a defense mechanism against infection by various pathogens. Human papillomavirus (HPV) infection induces an autophagy response, such as up-regulation of marker proteins formore » autophagy, in host keratinocytes. However, direct microscopic evidence for autophagy induction by HPV infection is still lacking. Here, I report an electron microscopic analysis of autophagosomes elicited by the entry of HPV pseudovirions (PsVs). HeLa cells showed enhanced infectivity for PsVs of HPV type 16 (16PsVs) when treated with an autophagy inhibitor, suggesting the involvement of autophagy in HPV infection. In HeLa cells inoculated with 16PsVs, transmission electron microscopy showed the presence of cup-shaped, double-membrane vesicles (phagophores) and double-membrane-bound vesicles, which are typical structures of autophagosomes. These double-membrane vesicles displayed a large lumen volume and incorporated 10–50 16PsVs particles in the lumen. These results demonstrate that autophagy is indeed induced during the HPV16 entry process and imply that autophagosomes are generated from the plasma membrane by HPV infection.« less

Quantitative characterization of chitosan in the skin by Fourier-transform infrared spectroscopic imaging and ninhydrin assay: application in transdermal sciences.

PubMed

Nawaz, A; Wong, T W

2016-07-01

The chitosan has been used as the primary excipient in transdermal particulate dosage form design. Its distribution pattern across the epidermis and dermis is not easily accessible through chemical assay and limited to radiolabelled molecules via quantitative autoradiography. This study explored Fourier-transform infrared spectroscopy imaging technique with built-in microscope as the means to examine chitosan molecular distribution over epidermis and dermis with the aid of histology operation. Fourier-transform infrared spectroscopy skin imaging was conducted using chitosan of varying molecular weights, deacetylation degrees, particle sizes and zeta potentials, obtained via microwave ligation of polymer chains at solution state. Both skin permeation and retention characteristics of chitosan increased with the use of smaller chitosan molecules with reduced acetyl content and size, and increased positive charge density. The ratio of epidermal to dermal chitosan content decreased with the use of these chitosan molecules as their accumulation in dermis (3.90% to 18.22%) was raised to a greater extent than epidermis (0.62% to 1.92%). A larger dermal chitosan accumulation nonetheless did not promote the transdermal polymer passage more than the epidermal chitosan. A small increase in epidermal chitosan content apparently could fluidize the stratum corneum and was more essential to dictate molecular permeation into dermis and systemic circulation. The histology technique aided Fourier-transform infrared spectroscopy imaging approach introduces a new dimension to the mechanistic aspect of chitosan in transdermal delivery. © 2015 The Authors Journal of Microscopy © 2015 Royal Microscopical Society.

A fast iterative convolution weighting approach for gridding-based direct Fourier three-dimensional reconstruction with correction for the contrast transfer function.

PubMed

Abrishami, V; Bilbao-Castro, J R; Vargas, J; Marabini, R; Carazo, J M; Sorzano, C O S

2015-10-01

We describe a fast and accurate method for the reconstruction of macromolecular complexes from a set of projections. Direct Fourier inversion (in which the Fourier Slice Theorem plays a central role) is a solution for dealing with this inverse problem. Unfortunately, the set of projections provides a non-equidistantly sampled version of the macromolecule Fourier transform in the single particle field (and, therefore, a direct Fourier inversion) may not be an optimal solution. In this paper, we introduce a gridding-based direct Fourier method for the three-dimensional reconstruction approach that uses a weighting technique to compute a uniform sampled Fourier transform. Moreover, the contrast transfer function of the microscope, which is a limiting factor in pursuing a high resolution reconstruction, is corrected by the algorithm. Parallelization of this algorithm, both on threads and on multiple CPU's, makes the process of three-dimensional reconstruction even faster. The experimental results show that our proposed gridding-based direct Fourier reconstruction is slightly more accurate than similar existing methods and presents a lower computational complexity both in terms of time and memory, thereby allowing its use on larger volumes. The algorithm is fully implemented in the open-source Xmipp package and is downloadable from http://xmipp.cnb.csic.es. Copyright © 2015 Elsevier B.V. All rights reserved.

An investigation into the rapid removal of tetracycline using multilayered graphene-phase biochar derived from waste chicken feather.

PubMed

Li, Huiqin; Hu, Jingtao; Meng, Yue; Su, Jinhua; Wang, Xiaojing

2017-12-15

This study investigated the removal of tetracycline (TC) using multilayered graphene-phase biochar (MGB) derived from waste chicken feather. MGB was produced through a two-stage carbonization and KOH-activation method. MGB was characterized by scanning electron microscopy (SEM), transmission electron microscope (TEM), Fourier transform infrared (FT-IR), Raman spectra, Zeta potential and elemental analysis. Various chemical functional groups were demonstrated on the surface of MGB. MGB was featured by a very large BET surface area of 1838m 2 /g. A rapid equilibrium (within 30s) and an ultrahigh removal efficiency (up to 99.65%) were obtained when MGB was used in the adsorption of TCs. The adsorption processes were temperature-dependent and the maximum adsorption capacity of MGB was 388.33mg/g at 30°C. The data of adsorption isotherms and kinetics were represented well by the Langmuir and Elovich models, respectively. The chemical monolayer adsorption could play an important role in this process. Furthermore, the adsorption of MGB was tolerant with wide pH, high ionic strength and even co-existing anions. Regeneration experiments indicated the removal efficiency was still satisfied (96.61%) even after four cycles. These results have important implications for the future application of animal waste-derived adsorbents in the treatment of wastewater containing antibiotic residues. Copyright © 2017 Elsevier B.V. All rights reserved.

Synthesis of graphene oxide grafted poly(lactic acid) with palladium nanoparticles and its application to serotonin sensing

NASA Astrophysics Data System (ADS)

Han, Hyoung Soon; You, Jung-Min; Jeong, Haesang; Jeon, Seungwon

2013-11-01

Graphene oxide (GO) has treated with methylene diphenyl diisocyanate (MDI) and subsequent 1,4-butanediol (BD) to create an anchoring OH site on the surface of GO (GO-MDI-OH). The OH groups of GO-MDI-OH were the initiators of the polymerization of poly(lactic acid) (PLA). The subsequent GO-g-PLA was synthesized by the polymerization reaction in the presence of GO-MDI-OH and PLA. The synthesized materials were characterized via 1H-NMR, Fourier transform infrared spectroscopy (FT-IR), Raman spectroscopy, X-ray photoelectron spectroscopy (XPS), thermal analysis (differential scanning calorimeter (DSC), and thermogravimetric analysis (TGA)). The surface morphologies and degree of dispersions at G-g-PLA-metals were observed using a field emission scanning electron microscope (FE-SEM) and a transmission electron microscopy (TEM). The electrical conductivity of G-g-PLA-Pd was largely enhanced compared with those of GO and GO-g-PLA. G-g-PLA-Pd was used for the electrochemical detection of serotonin. Electrocatalytic activities were verified from the cyclic voltammetry (CV) and amperometric response in a 0.1 M phosphate buffer solution (PBS). A significantly higher concentration range (0.1-100.0 μM) and a lower detection limit (8.0 × 10-8 M, where s/n = 3) were found at the G-g-PLA-Pd modified glassy carbon electrode (GCE).

Studies on magnetic properties of chemically synthesized crystalline calcium ferrite nanoparticles

NASA Astrophysics Data System (ADS)

Debnath, A.; Bera, A.; Chattopadhyay, K. K.; Saha, B.

2016-05-01

Spinel-type ferrites have taken a very important role for modern electronic industry. Most of these ferrites exhibit low-loss dielectric properties, high resistivity, low eddy current and also high temperature ferromagnetism. Calcium ferrite is one such important metal oxide which is environmentally safe, chemically stable, low cost and greatly abundant. This outstanding material of calcium ferrite is synthesized by a simple chemical precipitation method using NaOH as the precipitating agent. Ferric chloride anhydrous (FeCl3) and Calcium chloride dihydrate (CaCl2.2H2O) were used as iron and calcium sources respectively. The samples were heated at 200°C for 8h to obtain homogeneous powder of Calcium ferrite. The powders were characterized by using X-ray diffraction (XRD), field emission scanning electron microscope (FESEM), Transmission electrical microscopy (TEM), and Fourier transform infrared spectroscopic (FTIR) measurements. The polycrystalline nature of the sample was confirmed by X-ray diffraction study. The magnetic properties of the sample were investigated by vibrating sample magnetometer (VSM) measurements. Magnetization curve of the prepared sample depicts that as synthesized calcium ferrite nanoparticles have saturation magnetic moment of 1.74 emu/g and the coercivity of 35.08 Oe with superparamagnetic behavior. The synthesized calcium ferrite nanoparticles with such magnetic properties will be a candidate material for different applications in electronics and exploring its functionality in the field of recently developing semiconductor device physics and spintronics.

Preparation of highly active manganese oxides supported on functionalized MWNTs for low temperature NOx reduction with NH3

NASA Astrophysics Data System (ADS)

Pourkhalil, Mahnaz; Moghaddam, Abdolsamad Zarringhalam; Rashidi, Alimorad; Towfighi, Jafar; Mortazavi, Yadollah

2013-08-01

Manganese oxide catalysts (MnOx) supported on functionalized multi-walled carbon nanotubes (FMWNTs) for low temperature selective catalytic reduction (LTSCR) of nitrogen oxides (NOx) with NH3 in the presence of excess O2 were prepared by the incipient wetness impregnation method. These catalysts were characterized by N2 adsorption, Fourier transform infrared spectroscopy (FTIR), transmission electron microscope (TEM), X-ray diffraction (XRD), thermal gravimetric analysis (TGA) and H2-temperature programmed reduction (H2-TPR) methods. The effects of reaction temperature, MnOx loading, calcination temperature and calcination time were investigated. The presence of surface nitrate species under moderate calcination conditions may play a favorable role in the LTSCR of NOx with NH3. Under the reaction conditions of 200 °C, 1 bar, NO = NH3 = 900 ppm, O2 = 5 vol%, GHSV = 30,000 h-1 and 12 wt% MnOx, NOx conversion and N2 selectivity were 97% and 99.5%, respectively. The SCR activity was reduced in the presence of 100 ppm SO2 and 2.5 vol% H2O from 97% to 92% within 6 h at 200 °C, however such an effect was shown to be reversible by exposing the catalyst to a helium flow for 2 h at 350 °C due to thermal decomposition of ammonium sulphate salts.

Anticancer and enhanced antimicrobial activity of biosynthesizd silver nanoparticles against clinical pathogens

NASA Astrophysics Data System (ADS)

Rajeshkumar, Shanmugam; Malarkodi, Chelladurai; Vanaja, Mahendran; Annadurai, Gurusamy

2016-07-01

The present investigation shows the biosynthesis of eco-friendly silver nanoparticles using culture supernatant of Enterococcus sp. and study the effect of enhanced antimicrobial activity, anticancer activity against pathogenic bacteria, fungi and cancer cell lines. Silver nanoparticles was synthesized by adding 1 mM silver nitrate into the 100 ml of 24 h freshly prepared culture supernatant of Enterococcus sp. and were characterized by UV-vis spectroscopy, X-ray diffraction (XRD), Transmission Electron Microscope (TEM), Selected Area Diffraction X-Ray (SAED), Energy Dispersive X Ray (EDX) and Fourier Transform Infra red Spectroscopy (FT-IR). The synthesized silver nanoparticles were impregnated with commercial antibiotics for evaluation of enhanced antimicrobial activity. Further these synthesized silver nanoparticles were assessed for its anticancer activity against cancer cell lines. In this study crystalline structured nanoparticles with spherical in the size ranges from 10 to 80 nm and it shows excellent enhanced antimicrobial activity than the commercial antibiotics. The in vitro assay of silver nanoparticles on anticancer have great potential to inhibit the cell viability. Amide linkages and carboxylate groups of proteins from Enterococcus sp. may bind with silver ions and convert into nanoparticles. The activities of commercial antibiotics were enhanced by coating silver nanoparticles shows significant improved antimicrobial activity. Silver nanoparticles have the great potential to inhibit the cell viability of liver cancer cells lines (HepG2) and lung cancer cell lines (A549).

One-step electrospinning synthesis of TiO2/g-C3N4 nanofibers with enhanced photocatalytic properties

NASA Astrophysics Data System (ADS)

Tang, Qian; Meng, Xianfeng; Wang, Zhiying; Zhou, Jianwei; Tang, Hua

2018-02-01

TiO2/g-C3N4 composite nanofibers have been successfully synthesized by one-step electrospinning method, using titanium (IV) n-butoxide (TNBT) and urea as raw materials. The structure and compositions of TiO2/g-C3N4 samples are characterized by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), Diffuse reflectance spectroscopy (DRS), Scanning electron microscopy (SEM), Transmission electron microscope (TEM), X-ray photoelectron spectrometer (XPS) and Brunauer-Emmett-Teller (BET), respectively. The results show that the porous uniform TiO2/g-C3N4 composite nanofibers, with diameter of 100-150 nm, can be successfully prepared through electrospinning method combining 550 °C calcination process. The photocatalytic activity is evaluated by the degradation of rhodamine B (RhB) under simulated solar light. The enhanced catalytic activity is attributed predominantly to the heterojunction between TiO2 and g-C3N4, which promotes the transferring of carriers and prohibits their recombination. With the optimal doping amount of 0.6 g urea (corresponding to 3 g TNBT), the TiO2/g-C3N4 composite nanofibers exhibit the highest rate towards the photocatalytic degradation of RhB. A diagram is presented to explicate the mechanism of the whole catalytic experiment. This study might provide a promising future of applying green catalysts to solving water pollution problems.

Comparative study on the process behavior and reaction kinetics in sonocatalytic degradation of organic dyes by powder and nanotubes TiO2.

PubMed

Pang, Yean Ling; Abdullah, Ahmad Zuhairi

2012-05-01

Sonocatalytic degradation of various organic dyes (Congo Red, Reactive Blue 4, Methyl Orange, Rhodamine B and Methylene Blue) catalyzed by powder and nanotubes TiO(2) was studied. Both catalysts were characterized using transmission electron microscope (TEM), surface analyzer, Raman spectroscope and thermal gravimetric analyzer (TGA). Sonocatalytic activity of powder and nanotubes TiO(2) was elucidated based on the degradation of various organic dyes. The former catalyst was favorable for treatment of anionic dyes, while the latter was more beneficial for cationic dyes. Sonocatalytic activity of TiO(2) nanotubes could be up to four times as compared to TiO(2) powder under an ultrasonic power of 100 W and a frequency of 42 kHz. This was associated with the higher surface area and the electrostatic attraction between dye molecules and TiO(2) nanotubes. Fourier transform-infrared spectrometer (FT-IR) was used to identify changes that occurred on the functional group in Rhodamine B molecules and TiO(2) nanotubes after the reaction. Sonocatalytic degradation of Rhodamine B by TiO(2) nanotubes apparently followed the Langmuir-Hinshelwood adsorption kinetic model with surface reaction rate of 1.75 mg/L min. TiO(2) nanotubes were proven for their high potential to be applied in sonocatalytic degradation of organic dyes. Copyright © 2011 Elsevier B.V. All rights reserved.

Polypyrrole-coated LiCoO2 nanocomposite with enhanced electrochemical properties at high voltage for lithium-ion batteries

NASA Astrophysics Data System (ADS)

Cao, Jingchao; Hu, Guorong; Peng, Zhongdong; Du, Ke; Cao, Yanbing

2015-05-01

A conducting polypyrrole thin film is successfully coated onto the surface of LiCoO2 by a simple chemical polymerization method. The structure and morphology of pristine LiCoO2 and PPy-coated LiCoO2 are investigated by the techniques of X-ray diffraction (XRD), scanning electron microscopy (SEM) and transmission electron microscope (TEM). Energy dispersive X-ray spectroscopy (EDXS), Fourier transform infrared spectrometry (FTIR) and thermogravimetric analysis (TGA) further demonstrate the existence of PPy. The electrochemical properties of the composites are investigated by galvanostatic charge-discharge test and AC impedance measurements, which show that the conductive PPy film on the surface significantly decrease the charge-transfer resistance of LiCoO2. The PPy-coated LiCoO2 exhibits a good electrochemical performance, showing initial discharge capacity of 182 mAh g-1 and retains 94.3% after 170 cycles. However, the retention of pristine LiCoO2 is only 83.5%. The rate capability results show that the reversible capacity retention (10C/0.2C) of LiCoO2 increases from 52.4% to 80.1% after being coated with PPy. The continuously coated thin PPy film is just like a capsule shell, which can protect the core (LiCoO2) from corrosion causing by the HF attacking and greatly reduce the dissolution of Co into electrolyte.

Magnetic liposomes for colorectal cancer cells therapy by high-frequency magnetic field treatment

NASA Astrophysics Data System (ADS)

Hardiansyah, Andri; Huang, Li-Ying; Yang, Ming-Chien; Liu, Ting-Yu; Tsai, Sung-Chen; Yang, Chih-Yung; Kuo, Chih-Yu; Chan, Tzu-Yi; Zou, Hui-Ming; Lian, Wei-Nan; Lin, Chi-Hung

2014-09-01

In this study, we developed the cancer treatment through the combination of chemotherapy and thermotherapy using doxorubicin-loaded magnetic liposomes. The citric acid-coated magnetic nanoparticles (CAMNP, ca. 10 nm) and doxorubicin were encapsulated into the liposome (HSPC/DSPE/cholesterol = 12.5:1:8.25) by rotary evaporation and ultrasonication process. The resultant magnetic liposomes ( ca. 90 to 130 nm) were subject to characterization including transmission electron microscopy (TEM), dynamic light scattering (DLS), X-ray diffraction (XRD), zeta potential, Fourier transform infrared (FTIR) spectrophotometer, and fluorescence microscope. In vitro cytotoxicity of the drug carrier platform was investigated through 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay using L-929 cells, as the mammalian cell model. In vitro cytotoxicity and hyperthermia (inductive heating) studies were evaluated against colorectal cancer (CT-26 cells) with high-frequency magnetic field (HFMF) exposure. MTT assay revealed that these drug carriers exhibited no cytotoxicity against L-929 cells, suggesting excellent biocompatibility. When the magnetic liposomes with 1 μM doxorubicin was used to treat CT-26 cells in combination with HFMF exposure, approximately 56% cells were killed and found to be more effective than either hyperthermia or chemotherapy treatment individually. Therefore, these results show that the synergistic effects between chemotherapy (drug-controlled release) and hyperthermia increase the capability to kill cancer cells.

A Label-Free Photoluminescence Genosensor Using Nanostructured Magnesium Oxide for Cholera Detection

NASA Astrophysics Data System (ADS)

Patel, Manoj Kumar; Ali, Md. Azahar; Krishnan, Sadagopan; Agrawal, Ved Varun; Al Kheraif, Abdulaziz A.; Fouad, H.; Ansari, Z. A.; Ansari, S. G.; Malhotra, Bansi D.

2015-11-01

Nanomaterial-based photoluminescence (PL) diagnostic devices offer fast and highly sensitive detection of pesticides, DNA, and toxic agents. Here we report a label-free PL genosensor for sensitive detection of Vibrio cholerae that is based on a DNA hybridization strategy utilizing nanostructured magnesium oxide (nMgO; size >30 nm) particles. The morphology and size of the synthesized nMgO were determined by transmission electron microscopic (TEM) studies. The probe DNA (pDNA) was conjugated with nMgO and characterized by X-ray photoelectron and Fourier transform infrared spectroscopic techniques. The target complementary genomic DNA (cDNA) isolated from clinical samples of V. cholerae was subjected to DNA hybridization studies using the pDNA-nMgO complex and detection of the cDNA was accomplished by measuring changes in PL intensity. The PL peak intensity measured at 700 nm (red emission) increases with the increase in cDNA concentration. A linear range of response in the developed PL genosensor was observed from 100 to 500 ng/μL with a sensitivity of 1.306 emi/ng, detection limit of 3.133 ng/μL and a regression coefficient (R2) of 0.987. These results show that this ultrasensitive PL genosensor has the potential for applications in the clinical diagnosis of cholera.

Enhanced magneto-optical and photo-catalytic properties of transition metal cobalt (Co2+ ions) doped spinel MgFe2O4 ferrite nanocomposites

NASA Astrophysics Data System (ADS)

Abraham, A. Godlyn; Manikandan, A.; Manikandan, E.; Vadivel, S.; Jaganathan, S. K.; Baykal, A.; Renganathan, P. Sri

2018-04-01

In this study, spinel magnesium cobalt ferrite (CoxMg1-xFe2O4: x = 0.0, 0.2, 0.4, 0.6, 0.8 and 1.0) nanocomposites were synthesized successfully by modified sol-gel combustion method. Magnesium nitrate, cobalt nitrate and iron nitrate were used as the source of divalent (Mg2+ and Co2+) and trivalent (Fe3+) cations, respectively and urea were used as the reducing (fuel) agent. The effects of cobalt ions on morphology, structural, optical, magnetic and photo-catalytic properties of spinel CoxMg1-xFe2O4 nanocomposites were investigated. Various characterization methods, including X-ray powder diffraction (XRD), high resolution scanning electron microscope (HR-SEM), transmission electron microscopy (HR-TEM), energy-dispersive X-ray spectroscopy (EDX), Fourier transforms infrared (FT-IR) spectroscopy, vibrating sample magnetometer (VSM) and photo-catalytic degradation (PCD) activity were used to study the phase purity, microstructure, particle size, elemental composition, functional group determination, band gap calculation, magnetic properties and degradation efficiency of nanoparticles, respectively. The observed results showed that the final products consists cubic spinel phase with sphere-like nanoparticles morphologies. Furthermore, spinel Co0.6Mg0.4Fe2O4 nanocomposite showed highest PCD efficiency (98.55%) than other composition of ferrite nanoparticles.

One-pot synthesis and lubricity of fluorescent carbon dots applied on PCL-PEG-PCL hydrogel.

PubMed

Guo, Junde; Mei, Tangjie; Li, Yue; Hafezi, Mahshid; Lu, Hailin; Li, Jianhui; Dong, Guangneng

2018-06-12

This work presents a method for one-pot synthesis of N-doped nanometer-size carbon dots, which can be assembled with thermosensitive poly(ε-caprolactone)-poly(ethylene glycol)-poly(ε-caprolactone) (PCL-PEG-PCL, PCEC) hydrogel to achieve slow-release lubricity. The typical property of this green production was studied by fourier transform infrared (FT-IR), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS) and transmission electron microscope (TEM). The photoluminescence of composite PCEC/CDs hydrogel and its released solutions were characterized by ultraviolet spectrum, and the rheological properties were tested by rotary rheometer. Tribological performance of the released solution from composite PCEC/CDs hydrogel was obtained to compare with PBS and pure CDs solution. The experimental results reveal that the CDs contain the chemical groups of N-H, C-OH/C-O-C and -COOH, etc. In addition, the diameter of the CDs is in the range of 6~8 nm. The phase transition behavior of PCEC/CDs hydrogel can be still kept and its viscoelasticity hydrogel is improved by approximatively 7%. Furthermore, friction coefficient of the released solution from composite PCEC/CDs hydrogel decreases by about 70% than that of PBS. Besides, the wear condition can be improved by a lubricating transfer film formed by released CDs. This novel strategy for slow-release application is valuable for drug delivery and bio-tribology.

Design and synthesis of pH-sensitive polyamino-ester magneto-dendrimers: Surface functional groups effect on viability of human prostate carcinoma cell lines DU145.

PubMed

Dayyani, Nahid; Khoee, Sepideh; Ramazani, Ali

2015-06-15

Novel pH-sensitive, biocompatible and biodegradable magneto-dendrimers with OH and/or NH2 functional groups based on poly amino-ester were synthesized for delivery of anti-cancer drugs. Magnetite nanoparticles (MNPs) were synthesized by the co-precipitation method and their surfaces were modified by 3-aminopropyl triethoxysilane. The first and second generations of the magneto-dendrimer with hydroxyl end groups were produced by sequential acrylation and Michael addition reactions using the required amounts of acryloyl chloride and diethanolamine, respectively. The dendrimer containing amino functional surface groups up to second generation was synthesized by the same method using the necessary amounts of acryloyl chloride and ethylenediamine. These dendrimers were fully characterized by the Fourier transform infrared spectroscopy (FT-IR), thermogravimetric analysis (TGA), dynamic light scattering (DLS) and zeta potential analysis, vibrating-sample magnetometer (VSM), scanning electron microscope (SEM), transmission electron microscopy (TEM) and selected area electron diffraction (SAED). In-vitro release profiles of the drug-loaded magnetic nanoparticles and their cytotoxicity assay were investigated at two pHs (7.4 and 5.8). The hydrolytic degradation behavior of magneto-dendrimers was evaluated in PBS buffer. Our research suggests that magneto-dendrimers having amine or hydroxyl functional groups could be considered as the suitable nanocarriers for therapy applications. Copyright © 2015 Elsevier Masson SAS. All rights reserved.

Precursor preparation for Ca-Al layered double hydroxide to remove hexavalent chromium coexisting with calcium and magnesium chlorides

NASA Astrophysics Data System (ADS)

Zhong, Lihua; He, Xiaoman; Qu, Jun; Li, Xuewei; Lei, Zhiwu; Zhang, Qiwu; Liu, Xinzhong

2017-01-01

Al(OH)3 and Ca(OH)2 powders are co-ground to prepare a precursor which hydrates into a layered double hydroxide (LDH) phase by agitation in aqueous solution with target hexavalent chromium (Cr(VI)) at room temperature, to achieve an obvious improvement in removal efficiency of Cr(VI) through an easy incorporation into the structure. Although the prepared precursor transforms into LDH phases also when agitated in the solutions of calcium and magnesium chlorides, it incorporates Cr(VI) preferentially to the chloride salts when they coexist. The adsorption isotherm and kinetic studies show that the phenomena occurring on the Al-Ca precursor fit a pseudo-second-order kinetics with a Langmuir adsorption capacity of 59.45 mg/g. Besides, characterizations of the prepared precursor and the samples after adsorption are also performed by X-ray diffraction (XRD), Fourier transform infrared (FT-IR), Transmission electron microscope (TEM) to understand the reason of the preferential incorporation of Cr(VI) to the coexisting chloride salts during the LDH phase formation. Ca-Al precursor (C3A) was agitated in a hexavalent chromium (Cr(VI)) solution to form Al-Ca-CrO4 LDH product. Ca-Al-CrO4 LDH phase occurred preferentially to Ca-Al-MCl2 LDH phases in the solutions of calcium and magnesium chlorides, it incorporates Cr(VI) preferentially to the chloride salts when they coexist.

FPscope: a field-portable high-resolution microscope using a cellphone lens.

PubMed

Dong, Siyuan; Guo, Kaikai; Nanda, Pariksheet; Shiradkar, Radhika; Zheng, Guoan

2014-10-01

The large consumer market has made cellphone lens modules available at low-cost and in high-quality. In a conventional cellphone camera, the lens module is used to demagnify the scene onto the image plane of the camera, where image sensor is located. In this work, we report a 3D-printed high-resolution Fourier ptychographic microscope, termed FPscope, which uses a cellphone lens in a reverse manner. In our platform, we replace the image sensor with sample specimens, and use the cellphone lens to project the magnified image to the detector. To supersede the diffraction limit of the lens module, we use an LED array to illuminate the sample from different incident angles and synthesize the acquired images using the Fourier ptychographic algorithm. As a demonstration, we use the reported platform to acquire high-resolution images of resolution target and biological specimens, with a maximum synthetic numerical aperture (NA) of 0.5. We also show that, the depth-of-focus of the reported platform is about 0.1 mm, orders of magnitude longer than that of a conventional microscope objective with a similar NA. The reported platform may enable healthcare accesses in low-resource settings. It can also be used to demonstrate the concept of computational optics for educational purposes.

Synthesis and characterization of nanocrystalline graphite from coconut shell with heating process

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

Wachid, Frischa M., E-mail: frischamw@yahoo.com, E-mail: adhiyudhaperkasa@yahoo.com, E-mail: afandisar@yahoo.com, E-mail: nurulrosyidah92@gmail.com, E-mail: darminto@physics.its.ac.id; Perkasa, Adhi Y., E-mail: frischamw@yahoo.com, E-mail: adhiyudhaperkasa@yahoo.com, E-mail: afandisar@yahoo.com, E-mail: nurulrosyidah92@gmail.com, E-mail: darminto@physics.its.ac.id; Prasetya, Fandi A., E-mail: frischamw@yahoo.com, E-mail: adhiyudhaperkasa@yahoo.com, E-mail: afandisar@yahoo.com, E-mail: nurulrosyidah92@gmail.com, E-mail: darminto@physics.its.ac.id

Graphite were synthesized and characterized by heating process of coconut shell with varying temperature (400, 800 and 1000°C) and holding time (3 and 5 hours). After heating process, the samples were characterized by X-ray diffraction (XRD) and analyzed by X'pert HighScore Plus Software, Scanning Electron Microcope-Energy Dispersive X-Ray (SEM-EDX) and Transmission Electron Microscope-Energy Dispersive X-Ray (TEM-EDX). Graphite and londsdaelite phase were analyzed by XRD. According to EDX analysis, the sample was heated in 1000°C got the highest content of carbon. The amorphous carbon and nanocrystalline graphite were observed by SEM-EDX and TEM-EDX.

Clay minerals in primitive meteorites and interplanetary dust 2. Smectites and micas

NASA Technical Reports Server (NTRS)

Keller, L. P.; Zolensky, M. E.

1991-01-01

The classification is briefly summarized of stony meteorites and cosmic dust, and the mineralogy and chemistry is described of serpentine group minerals. The occurrence of smectites and micas in extraterrestrial materials is examined. The characterization of fine grained minerals in meteorites and IDPs relies heavily on electron beam instruments, especially the transmission electron microscope (TEM). Typically, phyllosilicates are identified by a combination of high resolution imaging of basal spacings, electron diffraction, and chemical analysis. Smectites can be difficult to differentiate from micas because the smectites lose their interlayer water and the interlayer partly collapse in the high vacuum of the TEM.

About the contrast of δ' precipitates in bulk Al-Cu-Li alloys in reflection mode with a field-emission scanning electron microscope at low accelerating voltage.

PubMed

Brodusch, Nicolas; Voisard, Frédéric; Gauvin, Raynald

2017-11-01

Characterising the impact of lithium additions in the precipitation sequence in Al-Li-Cu alloys is important to control the strengthening of the final material. Since now, transmission electron microscopy (TEM) at high beam voltage has been the technique of choice to monitor the size and spatial distribution of δ' precipitates (Al 3 Li). Here we report on the imaging of the δ' phase in such alloys using backscattered electrons (BSE) and low accelerating voltage in a high-resolution field-emission scanning electron microscope. By applying low-energy Ar + ion milling to the surface after mechanical polishing (MP), the MP-induced corroded layers were efficiently removed and permitted the δ's to be visible with a limited impact on the observed microstructure. The resulting BSE contrast between the δ's and the Al matrix was compared with that obtained using Monte Carlo modelling. The artefacts possibly resulting from the sample preparation procedure were reviewed and discussed and permitted to confirm that these precipitates were effectively the metastable δ's. The method described in this report necessitates less intensive sample preparation than that required for TEM and provides a much larger field of view and an easily interpretable contrast compared to the transmission techniques. © 2017 The Authors Journal of Microscopy © 2017 Royal Microscopical Society.

A study of over production and enhanced secretion of enzymes. Quarterly report 1

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

Dashek, W.V.

1992-12-28

The current project is concerned with the over-production and enhanced secretion of PPO, cellulase and lignin peroxidase. The project is divided into two segments: over-production of lignocellulolytic enzymes by genetic engineering methodologies and hyper-production and enhanced secretion of these enzymes by biochemical/electron microscopical techniques. The former approach employs recombinant DNA procedures, ligation of appropriate nuclease generated DNA fragments into a vector and the subsequent transformation of Escherichia coli to yield E. coli harboring a C. versicolor DNA insert. The biochemistry/electron microscopical method involves substrate induction and the time-dependent addition of respiration and PPO inhibitors to elevate C.versicolor`s ability to synthesizemore » and secrete lignocellulosic enzymes. In this connection, cell fractionation/kinetic analysis, TEM immunoelectron microscopic localization and TEM substrate localization of PPO are being employed to assess the route of secretion. Both approaches will culminate in the batch culture of either E. coli or C. versicolor, in a fermentor with the subsequent development of rapid isolation and purification procedures to yield elevated quantities of pure lignocellulosic enzymes. During the past year, research effort were directed toward determining the route of polyphenol oxidase (PPO) secretion by the wood-decay fungus, Coriolus versicolor. In addition, research activities were continued to over-produce and to purify PPO as well as define the time-dependent intra- and extra-cellular appearances of C. versicolor ligninases and cellulases.« less

Standardized Polyalthia longifolia leaf extract (PLME) inhibits cell proliferation and promotes apoptosis: The anti-cancer study with various microscopy methods.

PubMed

Vijayarathna, Soundararajan; Chen, Yeng; Kanwar, Jagat R; Sasidharan, Sreenivasan

2017-07-01

Over the years a number of microscopy methods have been developed to assess the changes in cells. Some non-invasive techniques such as holographic digital microscopy (HDM), which although does not destroy the cells, but helps to monitor the events that leads to initiation of apoptotic cell death. In this study, the apoptogenic property and the cytotoxic effect of P. longifolia leaf methanolic extract (PLME) against the human cervical carcinoma cells (HeLa) was studied using light microscope (LM), holographic digital microscopy (HDM), scanning electron microscope (SEM) and transmission electron microscope (TEM). The average IC 50 value of PLME against HeLa cells obtained by MTT and CyQuant assay was 22.00μg/mL at 24h. However, noncancerous Vero cells tested with PLME exhibited no cytotoxicity with the IC 50 value of 51.07μg/mL at 24h by using MTT assay. Cytological observations showed nuclear condensation, cell shrinkage, multinucleation, abnormalities of mitochondrial cristae, membrane blebbing, disappearance of microvilli and filopodia, narrowing of lamellipodia, holes, formation of numerous smaller vacuoles, cytoplasmic extrusions and formation of apoptotic bodies as confirmed collectively by HDM, LM, SEM and TEM. In conclusion, PLME was able to produce distinctive morphological features of HeLa cell death that corresponds to apoptosis. Copyright © 2017 Elsevier Masson SAS. All rights reserved.

To study the effect of doping concentration of silver on structural and optical properties of cadmium oxide (CdO) nanostructure

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

Kumar, Rajesh, E-mail: rkkaushik06@gmail.com; Dept. of Physics, Vaish College of Engineering, Rohtak-124001, Haryana; Sharma, Ashwani

The present work deals with study of structural and optical properties of Silver (Ag) doped Cadmium oxide (CdO) nanostructured synthesized by Chemical Co-precipitation Techniques followed by calcinations at small temperature. The doping concentrations were changing from 0.1 to 10 at% respectively. Structural analysis study of these calcined materials is carried out by X-ray diffraction (XRD), Scanning Electron Microscopy (SEM) and Transmission Electron Microscopy (TEM). The optical properties of calcined samples were investigating by Fourier transformation infrared (FTIR)spectroscopy, UV-Visible Spectroscopy (UV-Vis). The structural properties analysis results revels that crystallite size are in the range of nano region and TEM results aremore » quite in accordance with XRD results.« less

NASA Astrophysics Data System (ADS)

Wang, Mao-Hua; Zhang, Bo; Zhou, Fu

2014-07-01

Silica was homogeneously coated on the surface of CaCu3Ti4O12 (CCTO) particles via the sol-gel method. The obtained powders were characterized by x-ray diffraction analysis, Fourier-transform infrared spectroscopy, transmission electron microscopy (TEM), energy-dispersive spectroscopy, scanning electron microscopy, and zeta potential analysis. The results demonstrate that there were silica layers on the surface of the CCTO particles. Physical and dielectric properties of silica-coated CCTO were also studied. TEM imaging showed that the thickness of the silica layer on the CCTO particles was about 20 nm to 35 nm. The specimen coated with 1.0 wt.% silica showed the maximum relative density of 96.7% with high dielectric constant (12.78 × 104) and low dielectric loss (0.005) at 20°C after sintering at 1000°C for 6 h.

Hydroxyapatite nanocrystals: simple preparation, characterization and formation mechanism.

PubMed

Mohandes, Fatemeh; Salavati-Niasari, Masoud; Fathi, Mohammadhossein; Fereshteh, Zeinab

2014-12-01

Crystalline hydroxyapatite (HAP) nanoparticles and nanorods have been successfully synthesized via a simple precipitation method. To control the shape and particle size of HAP nanocrystals, coordination ligands derived from 2-hydroxy-1-naphthaldehyde were first prepared, characterized by Fourier transform infrared (FT-IR) and proton nuclear magnetic resonance ((1)H-NMR) spectroscopies, and finally applied in the synthesis process of HAP. On the other hand, the HAP nanocrystals were also characterized by several techniques including powder X-ray diffraction (XRD), field-emission scanning electron microscopy (FE-SEM) and transmission electron microscopy (TEM). According to the FE-SEM and TEM micrographs, it was found that the morphology and crystallinity of the HAP powders depended on the coordination mode of the ligands. Copyright © 2014 Elsevier B.V. All rights reserved.

Synthesis, characterization and antibacterial property of ZnO:Mg nanoparticles

NASA Astrophysics Data System (ADS)

Kompany, A.; Madahi, P.; Shahtahmasbi, N.; Mashreghi, M.

2012-09-01

Sol-gel method was successfully used for the synthesis of ZnO nanoparticles (NPs) doped with different concentrations of Mg and the structural, optical and antibacterial properties of the nanoparticles were studied. The synthesized ZnO:Mg powders were characterized using x-ray diffraction (XRD), transmission electron microscopy (TEM), Fourier transformation Infrared (FTIR) and UV-Vis spectroscopy. It was revealed that the samples have hexagonal Wurtzite structure, and the phase segregation takes place for 15% Mg content. TEM images show that the average size of the particles is about 50 nm. Also, the antibacterial activities of the nanoparticles were tested against Escherichia coli (Gram negative) cultures. ZnO:Mg nanofluid showed good antibacterial activity which increases with the increase of NPs concentration, and decreases slightly with the amount of Mg.

Synthesis and characterization of dextran-coated iron oxide nanoparticles

NASA Astrophysics Data System (ADS)

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

2018-03-01

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

Plasmonic characterization of photo-induced silver nanoparticles extracted from silver halide based TEM film

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

Sudheer,, E-mail: sudheer@rrcat.gov.in; Tiwari, P.; Rai, V. N.

The plasmonic responses of silver nanoparticles extracted from silver halide based electron microscope film are investigated. Photo-reduction process is carried out to convert the silver halide grains into the metallic silver. The centrifuge technique is used for separating the silver nanoparticles from the residual solution. Morphological study performed by field emission scanning electron microscope (FESEM) shows that all the nanoparticles have an average diameter of ~120 nm with a high degree of mono dispersion in size. The localized surface plasmon resonance (LSPR) absorption peak at ~537 nm confirms the presence of large size silver nanoparticles.

Nanoscale welding of multi-walled carbon nanotubes by 1064 nm fiber laser

NASA Astrophysics Data System (ADS)

Yuan, Yanping; Liu, Zhi; Zhang, Kaihu; Han, Weina; Chen, Jimin

2018-07-01

This study proposes an efficient approach which uses 1064 nm continuous fiber laser to achieve nanoscale welding of crossed multi-walled carbon nanotubes (MWCNTs). By changing the irradiation time, different quality of nanoscale welding is obtained. The morphology changes are investigated by scanning electron microscope (SEM) and transmission electron microscope (TEM). The experiments demonstrate that better quality of MWCNTs nanoscale welding after 3 s irradiation can be obtained. It is found that new graphene layers between crossed nanotubes induced by laser make the nanoscale welding achieved due to the absorption of laser energy.

The Application of High-Resolution Electron Microscopy to Problems in Solid State Chemistry: The Exploits of a Peeping TEM.

ERIC Educational Resources Information Center

Eyring, LeRoy

1980-01-01

Describes methods for using the high-resolution electron microscope in conjunction with other tools to reveal the identity and environment of atoms. Problems discussed include the ultimate structure of real crystalline solids including defect structure and the mechanisms of chemical reactions. (CS)

Rapid Sintering of Li₂O-Nb₂O₅-TiO₂ Solid Solution by Air Pressure Control and Clarification of Its Mechanism.

PubMed

Nakano, Hiromi; Kamimoto, Konatsu; Yamamoto, Takahisa; Furuta, Yoshio

2018-06-11

We first successfully synthesized Li 1+ x − y Nb 1− x −3 y Ti x +4 y O₃ (LNT) solid solutions (0.13 ≤ x ≤ 0.18, 0 ≤ y ≤ 0.06) rapidly at 1373 K for one hour under 0.35 MPa by the controlling of air pressure using an air-pressure control atmosphere furnace. The composition is a formation area of a superstructure for LNT, in which the periodical intergrowth layer was formed in the matrix, and where it can be controlled by Ti content. Therefore, the sintering time depended on Ti content, and annealing was repeated for over 24 h until a homogeneous structure was formed using a conventional electric furnace. We clarified the mechanism of the rapid sintering using various microscale to nanoscale characterization techniques: X-ray diffraction, a scanning electron microscope, a transmission electron microscope (TEM), a Cs-corrected scanning TEM equipped with electron energy-loss spectroscopy, and X-ray absorption fine structure spectroscopy.

Optoelectronic and Electrochemical Properties of Vanadium Pentoxide Nanowires Synthesized by Vapor-Solid Process

PubMed Central

Pan, Ko-Ying; Wei, Da-Hua

2016-01-01

Substantial synthetic vanadium pentoxide (V2O5) nanowires were successfully produced by a vapor-solid (VS) method of thermal evaporation without using precursors as nucleation sites for single crystalline V2O5 nanowires with a (110) growth plane. The micromorphology and microstructure of V2O5 nanowires were analyzed by scanning electron microscope (SEM), energy-dispersive X-ray spectroscope (EDS), transmission electron microscope (TEM) and X-ray diffraction (XRD). The spiral growth mechanism of V2O5 nanowires in the VS process is proved by a TEM image. The photo-luminescence (PL) spectrum of V2O5 nanowires shows intrinsic (410 nm and 560 nm) and defect-related (710 nm) emissions, which are ascribable to the bound of inter-band transitions (V 3d conduction band to O 2p valence band). The electrical resistivity could be evaluated as 64.62 Ω·cm via four-point probe method. The potential differences between oxidation peak and reduction peak are 0.861 V and 0.470 V for the first and 10th cycle, respectively. PMID:28335268

Nanostructures formed by cyclodextrin covered procainamide through supramolecular self assembly - Spectral and molecular modeling study

NASA Astrophysics Data System (ADS)

Rajendiran, N.; Mohandoss, T.; Sankaranarayanan, R. K.

2015-02-01

Inclusion complexation behavior of procainamide (PCA) with two cyclodextrins (α-CD and β-CD) were analyzed by absorption, fluorescence, scanning electron microscope (SEM), transmission electron microscope (TEM), Raman image, FT-IR, differential scanning colorimeter (DSC), Powder X ray diffraction (XRD) and 1H NMR. Blue shift was observed in β-CD whereas no significant spectral shift observed in α-CD. The inclusion complex formation results suggest that water molecules also present in the inside of the CD cavity. The present study revealed that the phenyl ring of the PCA drug is entrapped in the CD cavity. Cyclodextrin studies show that PCA forms 1:2 inclusion complex with α-CD and β-CD. PCA:α-CD complex form nano-sized particles (46 nm) and PCA:β-CD complex form self-assembled to micro-sized tubular structures. The shape-shifting of 2D nanosheets into 1D microtubes by simple rolling mechanism were analysed by micro-Raman and TEM images. Thermodynamic parameters (ΔH, ΔG and ΔS) of inclusion process were determined from semiempirical PM3 calculations.

Characterization of Sulfur and Nanostructured Sulfur Battery Cathodes in Electron Microscopy Without Sublimation Artifacts

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

Levin, Barnaby D. A.; Zachman, Michael J.; Werner, Jörg G.

Abstract Lithium sulfur (Li–S) batteries have the potential to provide higher energy storage density at lower cost than conventional lithium ion batteries. A key challenge for Li–S batteries is the loss of sulfur to the electrolyte during cycling. This loss can be mitigated by sequestering the sulfur in nanostructured carbon–sulfur composites. The nanoscale characterization of the sulfur distribution within these complex nanostructured electrodes is normally performed by electron microscopy, but sulfur sublimates and redistributes in the high-vacuum conditions of conventional electron microscopes. The resulting sublimation artifacts render characterization of sulfur in conventional electron microscopes problematic and unreliable. Here, we demonstratemore » two techniques, cryogenic transmission electron microscopy (cryo-TEM) and scanning electron microscopy in air (airSEM), that enable the reliable characterization of sulfur across multiple length scales by suppressing sulfur sublimation. We use cryo-TEM and airSEM to examine carbon–sulfur composites synthesized for use as Li–S battery cathodes, noting several cases where the commonly employed sulfur melt infusion method is highly inefficient at infiltrating sulfur into porous carbon hosts.« less

Development of an analytical environmental TEM system and its application.

PubMed

Kishita, Keisuke; Sakai, Hisashi; Tanaka, Hiromochi; Saka, Hiroyasu; Kuroda, Kotaro; Sakamoto, Masayuki; Watabe, Akira; Kamino, Takeo

2009-12-01

Many automotive materials, such as catalysts and fuel cell materials, undergo significant changes in structure or properties when subjected to temperature change or the addition of a gas. For this reason, in the development of these materials, it is important to study the behavior of the material under controlled temperatures and gaseous atmospheres. Recently, a new environmental transmission electron microscope (TEM) has been developed for observation with a high resolution at high temperatures and under gaseous atmospheres, thus making it possible to analyze reaction processes in details. Also, the new TEM provides a high degree of reproducibility of observation conditions, thus making it possible to compare and validate observation of various specimens under a given set of conditions. Furthermore, easiness of gas condition and temperature control can provide a powerful tool for the studying of the mechanism of material change, such as oxidation and reduction reactions.

Cryo-FIB specimen preparation for use in a cartridge-type cryo-TEM.

PubMed

He, Jie; Hsieh, Chyongere; Wu, Yongping; Schmelzer, Thomas; Wang, Pan; Lin, Ying; Marko, Michael; Sui, Haixin

2017-08-01

Cryo-electron tomography (cryo-ET) is a well-established technique for studying 3D structural details of subcellular macromolecular complexes and organelles in their nearly native context in the cell. A primary limitation of the application of cryo-ET is the accessible specimen thickness, which is less than the diameters of almost all eukaryotic cells. It has been shown that focused ion beam (FIB) milling can be used to prepare thin, distortion-free lamellae of frozen biological material for high-resolution cryo-ET. Commercial cryosystems are available for cryo-FIB specimen preparation, however re-engineering and additional fixtures are often essential for reliable results with a particular cryo-FIB and cryo-transmission electron microscope (cryo-TEM). Here, we describe our optimized protocol and modified instrumentation for cryo-FIB milling to produce thin lamellae and subsequent damage-free cryotransfer of the lamellae into our cartridge-type cryo-TEM. Published by Elsevier Inc.

Making the practically impossible "Merely difficult"--Cryogenic FIB lift-out for "Damage free" soft matter imaging.

PubMed

Parmenter, Christopher D J; Fay, Michael W; Hartfield, Cheryl; Eltaher, Hoda M

2016-04-01

The preparation of thinned lamellae from bulk samples for transmission electron microscopy (TEM) analysis has been possible in the focussed ion beam scanning electron microscope (FIB-SEM) for over 20 years via the in situ lift-out method. Lift-out offers a fast and site specific preparation method for TEM analysis, typically in the field of materials science. More recently it has been applied to a low-water content biological sample (Rubino 2012). This work presents the successful lift-out of high-water content lamellae, under cryogenic conditions (cryo-FIB lift-out) and using a nanomanipulator retaining its full range of motion, which are advances on the work previously done by Rubino (2012). Strategies are explored for maintaining cryogenic conditions, grid attachment using cryo-condensation of water and protection of the lamella when transferring to the TEM. © 2016 Wiley Periodicals, Inc.

Chapter 14: Electron Microscopy on Thin Films for Solar Cells

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

Romero, Manuel; Abou-Ras, Daniel; Nichterwitz, Melanie

2016-07-22

This chapter overviews the various techniques applied in scanning electron microscopy (SEM) and transmission electron microscopy (TEM), and highlights their possibilities and also limitations. It gives the various imaging and analysis techniques applied on a scanning electron microscope. The chapter shows that imaging is divided into that making use of secondary electrons (SEs) and of backscattered electrons (BSEs), resulting in different contrasts in the images and thus providing information on compositions, microstructures, and surface potentials. Whenever aiming for imaging and analyses at scales of down to the angstroms range, TEM and its related techniques are appropriate tools. In many cases,more » also SEM techniques provide the access to various material properties of the individual layers, not requiring specimen preparation as time consuming as TEM techniques. Finally, the chapter dedicates to cross-sectional specimen preparation for electron microscopy. The preparation decides indeed on the quality of imaging and analyses.« less

Distortion of DNA Origami on Graphene Imaged with Advanced TEM Techniques.

PubMed

Kabiri, Yoones; Ananth, Adithya N; van der Torre, Jaco; Katan, Allard; Hong, Jin-Yong; Malladi, Sairam; Kong, Jing; Zandbergen, Henny; Dekker, Cees

2017-08-01

While graphene may appear to be the ultimate support membrane for transmission electron microscopy (TEM) imaging of DNA nanostructures, very little is known if it poses an advantage over conventional carbon supports in terms of resolution and contrast. Microscopic investigations are carried out on DNA origami nanoplates that are supported onto freestanding graphene, using advanced TEM techniques, including a new dark-field technique that is recently developed in our lab. TEM images of stained and unstained DNA origami are presented with high contrast on both graphene and amorphous carbon membranes. On graphene, the images of the origami plates show severe unwanted distortions, where the rectangular shape of the nanoplates is significantly distorted. From a number of comparative control experiments, it is demonstrated that neither staining agents, nor screening ions, nor the level of electron-beam irradiation cause this distortion. Instead, it is suggested that origami nanoplates are distorted due to hydrophobic interaction of the DNA bases with graphene upon adsorption of the DNA origami nanoplates. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Thinning of Large Biological Cells for Cryo-TEM Characterization by Cryo-FIB Milling

PubMed Central

Strunk, Korrinn M.; Ke, Danxia; Gray, Jennifer L.; Zhang, Peijun

2013-01-01

SUMMARY Focused ion beam milling at cryogenic temperatures (cryo-FIB) is a valuable tool that can be used to thin vitreous biological specimens for subsequent imaging and analysis in a cryo-transmission electron microscope (cryo-TEM) in their frozen-hydrated state. This technique offers the potential benefit of eliminating the mechanical artifacts that are typically found with cryo-ultramicrotomy. However, due to the additional complexity in transferring samples in and out of the FIB, contamination and devitrification of the amorphous ice is commonly encountered. In order to address these problems, we have designed a new sample cryo-shuttle that specifically accepts Polara TEM cartridges directly in order to simplify the transfer process between the FIB and TEM. We used the quality of the ice in the sample as an indicator to test various parameters used the process, and demonstrated with successful milling of large mammalian cells. By comparing the results from larger HeLa cells to those from E. coli cells, we discuss some of the artifacts and challenges we have encountered using this technique. PMID:22906009

Laterally modulated excitation microscopy: improvement of resolution by using a diffraction grating

NASA Astrophysics Data System (ADS)

Heintzmann, Rainer; Cremer, Christoph G.

1999-01-01

High spatial frequencies in the illuminating light of microscopes lead to a shift of the object spatial frequencies detectable through the objective lens. If a suitable procedure is found for evaluation of the measured data, a microscopic image with a higher resolution than under flat illumination can be obtained. A simple method for generation of a laterally modulated illumination pattern is discussed here. A specially constructed diffraction grating was inserted in the illumination beam path at the conjugate object plane (position of the adjustable aperture) and projected through the objective into the object. Microscopic beads were imaged with this method and evaluated with an algorithm based on the structure of the Fourier space. The results indicate an improvement of resolution.

Infrared imaging of cotton fibers using a focal-plane array detector

USDA-ARS?s Scientific Manuscript database

Vibrational spectroscopy studies can be used to examine the quality and structure of cotton fibers. An emerging area of research relates to the imaging of cotton fibers. Herein, we report the use of a Fourier-transform infrared (FTIR) microscope to image developing cotton fibers. Studies were perfor...

Chitosan/banana peel powder nanocomposites for wound dressing application: Preparation and characterization.

PubMed

Kamel, Nagwa A; Abd El-Messieh, Salwa L; Saleh, Neveen M

2017-03-01

Wound infection is a serious infection has been spread worldwide. In order to provide fast aid treatments for such infection, banana peels have been incorporated within chitosan as wound dressing. Banana was collected from Egyptian markets peeled and the dried peels were grounded to powder, Incorporated as nano fillers within chitosan matrix with different concentrations (0, 2, 5 and 10wt%). Glycerol was added as plasticizer and crosslinker to the membranes. The banana peel powder (BPP) particle shape and size were determined using Transmission Electron Microscope (TEM), The homogeneity and distribution of BPP in the membranes were investigated through Scanning Electron Microscope (SEM). The interaction between BPP and chitosan was characterized by Fourier Transform Infrared (FTIR). The dielectric properties of chitosan and BPP-chitosan membranes studied via dielectric constant, dielectric loss and conductivity measurements over a frequency range 100Hz up to 100kHz. The curves relating ε″ and the applied frequency are broad enough reflecting more than one relaxation process. These processes may be attributed to the relaxation processes of the main chain and its related motions. The higher values of ε″ at low frequency range may be a combination of the losses due to the electrical conductivity and the interfacial polarization process called "Maxwell Wagner Sillers" effect. By increasing BPP content in the sample a pronounced shift towards lower frequency was noticed. This shift may be due to some sort of polymer/filler interaction which causes an increase in the relaxed units and consequently the relaxation time. The addition of BPP decreases the swelling degree of chitosan matrix. The antimicrobial properties of the membranes were done against Gram positive, Gram negative bacteria and yeast. The results showed that chitosan/BPP membranes have a synergistic action with the highest activity at 10wt%. Moreover, Candida albicans was the most sensitive strain recorded for these membranes. Copyright © 2016 Elsevier B.V. All rights reserved.

Electron microscopic study of soot particulate matter emissions from aircraft turbine engines.

PubMed

Liati, Anthi; Brem, Benjamin T; Durdina, Lukas; Vögtli, Melanie; Dasilva, Yadira Arroyo Rojas; Eggenschwiler, Panayotis Dimopoulos; Wang, Jing

2014-09-16

The microscopic characteristics of soot particulate matter (PM) in gas turbine exhaust are critical for an accurate assessment of the potential impacts of the aviation industry on the environment and human health. The morphology and internal structure of soot particles emitted from a CFM 56-7B26/3 turbofan engine were analyzed in an electron microscopic study, down to the nanoscale, for ∼ 100%, ∼ 65%, and ∼ 7% static engine thrust as a proxy for takeoff, cruising, and taxiing, respectively. Sampling was performed directly on transmission electron microscopy (TEM) grids with a state-of-the-art sampling system designed for nonvolatile particulate matter. The electron microscopy results reveal that ∼ 100% thrust produces the highest amount of soot, the highest soot particle volume, and the largest and most crystalline primary soot particles with the lowest oxidative reactivity. The opposite is the case for soot produced during taxiing, where primary soot particles are smallest and most reactive and the soot amount and volume are lowest. The microscopic characteristics of cruising condition soot resemble the ones of the ∼ 100% thrust conditions, but they are more moderate. Real time online measurements of number and mass concentration show also a clear correlation with engine thrust level, comparable with the TEM study. The results of the present work, in particular the small size of primary soot particles present in the exhaust (modes of 24, 20, and 13 nm in diameter for ∼ 100%, ∼ 65% and ∼ 7% engine thrust, respectively) could be a concern for human health and the environment and merit further study. This work further emphasizes the significance of the detailed morphological characteristics of soot for assessing environmental impacts.

Improvement of the High Fluence Irradiation Facility at the University of Tokyo

NASA Astrophysics Data System (ADS)

Murakami, Kenta; Iwai, Takeo; Abe, Hiroaki; Sekimura, Naoto

2016-08-01

This paper reports the modification of the High Fluence Irradiation Facility at the University of Tokyo (HIT). The HIT facility was severely damaged during the 2011 earthquake, which occurred off the Pacific coast of Tohoku. A damaged 1.0 MV tandem Cockcroft-Walton accelerator was replaced with a 1.7 MV accelerator, which was formerly used in another campus of the university. A decision was made to maintain dual-beam irradiation capability by repairing the 3.75 MV single-ended Van de Graaff accelerator and reconstructing the related beamlines. A new beamline was connected with a 200 kV transmission electron microscope (TEM) to perform in-situ TEM observation under ion irradiation.

Transformation of multiwall carbon nanotubes to onions with layers cross-linked by sp3 bonds under high pressure and shear deformation

NASA Astrophysics Data System (ADS)

Pankov, A. M.; Bredikhina, A. S.; Kulnitskiy, B. A.; Perezhogin, I. A.; Skryleva, E. A.; Parkhomenko, Yu. N.; Popov, M. Yu.; Blank, V. D.

2017-08-01

A pressure-induced phase transition of multiwall carbon nanotubes (MWNT) to a new structure at room temperature is studied using a shear diamond anvil cell, X-ray photoelectron spectra (XPS), transmission electron microscope (TEM) and Raman procedures. We observe a cardinal pressure-induced change in the nanoparticles shape from multi-shell tubes to multi-shell spheres. MWNT transforms to onions with layers cross-linked by sp3 bonds under the 45-65 GPa compressive stress combined with shear deformation at room temperature. TEM and XPS results show that about 40% of the carbon atoms in the new phase are sp3-bounded.

Cross-sectional TEM specimen preparation for W/B{sub 4}C multilayer sample using FIB

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

Mondal, Puspen, E-mail: puspen@rrcat.gov.in; Pradhan, P. C.; Tiwari, Pragya

2016-05-23

A recent emergence of a cross-beam scanning electron microscopy (SEM)/focused-ion-beam (FIB) system have given choice to fabricate cross-sectional transmission electron microscopy (TEM) specimen of thin film multilayer sample. A 300 layer pair thin film multilayer sample of W/B{sub 4}C was used to demonstrate the specimen lift-out technique in very short time as compared to conventional cross-sectional sample preparation technique. To get large area electron transparent sample, sample prepared by FIB is followed by Ar{sup +} ion polishing at 2 kV with grazing incident. The prepared cross-sectional sample was characterized by transmission electron microscope.

Analysis of Local Structure, Chemistry and Bonding by Electron Energy Loss Spectroscopy

NASA Astrophysics Data System (ADS)

Mayer, Joachim

In the present chapter, the reader will first be introduced briefly to the basic principles of analytical transmission electron microscopy (ATEM) with special emphasis on electron energy-loss spectroscopy (EELS) and energy-filtering TEM. The quantification of spectra to obtain chemical information and the origin and interpretation of near-edge fine structures in EELS (ELNES) are discussed. Special attention will be given to the characterization of internal interfaces and the literature in this area will be reviewed. Selected examples of the application of ATEM in the investigation of internal interfaces will be given. These examples include both EELS in the energy-filtering TEM and in the scanning transmission electron microscope (STEM).

Spectral analysis of scattered light from flowers' petals

NASA Astrophysics Data System (ADS)

Ozawa, Atsumi; Uehara, Tomomi; Sekiguchi, Fumihiko; Imai, Hajime

2009-07-01

A new method was developed for studying absorption characteristics of opaque samples based on the light scattering spectroscopy. Measurements were made in white, red and violet petals of Petunia hybrida, and gave the absorption spectra in a non-destructive manner without damaging the cell structures of the petal. The red petal has absorption peak at 550 nm and the violet has three absorption peaks: at 450, 670, and 550 nm. The results were discussed in correlation with the microscopic cell structures of the petal observed with optical microscope and transmission electron microscopy (TEM). Only the cells placed in the surface have the pigments giving the color of the petal.

Cryo-electron microscopy and cryo-electron tomography of nanoparticles.

PubMed

Stewart, Phoebe L

2017-03-01

Cryo-transmission electron microscopy (cryo-TEM or cryo-EM) and cryo-electron tomography (cryo-ET) offer robust and powerful ways to visualize nanoparticles. These techniques involve imaging of the sample in a frozen-hydrated state, allowing visualization of nanoparticles essentially as they exist in solution. Cryo-TEM grid preparation can be performed with the sample in aqueous solvents or in various organic and ionic solvents. Two-dimensional (2D) cryo-TEM provides a direct way to visualize the polydispersity within a nanoparticle preparation. Fourier transforms of cryo-TEM images can confirm the structural periodicity within a sample. While measurement of specimen parameters can be performed with 2D TEM images, determination of a three-dimensional (3D) structure often facilitates more spatially accurate quantization. 3D structures can be determined in one of two ways. If the nanoparticle has a homogeneous structure, then 2D projection images of different particles can be averaged using a computational process referred to as single particle reconstruction. Alternatively, if the nanoparticle has a heterogeneous structure, then a structure can be generated by cryo-ET. This involves collecting a tilt-series of 2D projection images for a defined region of the grid, which can be used to generate a 3D tomogram. Occasionally it is advantageous to calculate both a single particle reconstruction, to reveal the regular portions of a nanoparticle structure, and a cryo-electron tomogram, to reveal the irregular features. A sampling of 2D cryo-TEM images and 3D structures are presented for protein based, DNA based, lipid based, and polymer based nanoparticles. WIREs Nanomed Nanobiotechnol 2017, 9:e1417. doi: 10.1002/wnan.1417 For further resources related to this article, please visit the WIREs website. © 2016 Wiley Periodicals, Inc.

Apparatus and methods for controlling electron microscope stages

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

Duden, Thomas

Methods and apparatus for generating an image of a specimen with a microscope (e.g., TEM) are disclosed. In one aspect, the microscope may generally include a beam generator, a stage, a detector, and an image generator. A plurality of crystal parameters, which describe a plurality of properties of a crystal sample, are received. In a display associated with the microscope, an interactive control sphere based at least in part on the received crystal parameters and that is rotatable by a user to different sphere orientations is presented. The sphere includes a plurality of stage coordinates that correspond to a pluralitymore » of positions of the stage and a plurality of crystallographic pole coordinates that correspond to a plurality of polar orientations of the crystal sample. Movement of the sphere causes movement of the stage, wherein the stage coordinates move in conjunction with the crystallographic coordinates represented by pole positions so as to show a relationship between stage positions and the pole positions.« less

Efficient and accurate two-scale FE-FFT-based prediction of the effective material behavior of elasto-viscoplastic polycrystals

NASA Astrophysics Data System (ADS)

Kochmann, Julian; Wulfinghoff, Stephan; Ehle, Lisa; Mayer, Joachim; Svendsen, Bob; Reese, Stefanie

2018-06-01

Recently, two-scale FE-FFT-based methods (e.g., Spahn et al. in Comput Methods Appl Mech Eng 268:871-883, 2014; Kochmann et al. in Comput Methods Appl Mech Eng 305:89-110, 2016) have been proposed to predict the microscopic and overall mechanical behavior of heterogeneous materials. The purpose of this work is the extension to elasto-viscoplastic polycrystals, efficient and robust Fourier solvers and the prediction of micromechanical fields during macroscopic deformation processes. Assuming scale separation, the macroscopic problem is solved using the finite element method. The solution of the microscopic problem, which is embedded as a periodic unit cell (UC) in each macroscopic integration point, is found by employing fast Fourier transforms, fixed-point and Newton-Krylov methods. The overall material behavior is defined by the mean UC response. In order to ensure spatially converged micromechanical fields as well as feasible overall CPU times, an efficient but simple solution strategy for two-scale simulations is proposed. As an example, the constitutive behavior of 42CrMo4 steel is predicted during macroscopic three-point bending tests.

Efficient and accurate two-scale FE-FFT-based prediction of the effective material behavior of elasto-viscoplastic polycrystals

NASA Astrophysics Data System (ADS)

Kochmann, Julian; Wulfinghoff, Stephan; Ehle, Lisa; Mayer, Joachim; Svendsen, Bob; Reese, Stefanie

2017-09-01

Recently, two-scale FE-FFT-based methods (e.g., Spahn et al. in Comput Methods Appl Mech Eng 268:871-883, 2014; Kochmann et al. in Comput Methods Appl Mech Eng 305:89-110, 2016) have been proposed to predict the microscopic and overall mechanical behavior of heterogeneous materials. The purpose of this work is the extension to elasto-viscoplastic polycrystals, efficient and robust Fourier solvers and the prediction of micromechanical fields during macroscopic deformation processes. Assuming scale separation, the macroscopic problem is solved using the finite element method. The solution of the microscopic problem, which is embedded as a periodic unit cell (UC) in each macroscopic integration point, is found by employing fast Fourier transforms, fixed-point and Newton-Krylov methods. The overall material behavior is defined by the mean UC response. In order to ensure spatially converged micromechanical fields as well as feasible overall CPU times, an efficient but simple solution strategy for two-scale simulations is proposed. As an example, the constitutive behavior of 42CrMo4 steel is predicted during macroscopic three-point bending tests.

FIMic: design for ultimate 3D-integral microscopy of in-vivo biological samples

PubMed Central

Scrofani, G.; Sola-Pikabea, J.; Llavador, A.; Sanchez-Ortiga, E.; Barreiro, J. C.; Saavedra, G.; Garcia-Sucerquia, J.; Martínez-Corral, M.

2017-01-01

In this work, Fourier integral microscope (FIMic), an ultimate design of 3D-integral microscopy, is presented. By placing a multiplexing microlens array at the aperture stop of the microscope objective of the host microscope, FIMic shows extended depth of field and enhanced lateral resolution in comparison with regular integral microscopy. As FIMic directly produces a set of orthographic views of the 3D-micrometer-sized sample, it is suitable for real-time imaging. Following regular integral-imaging reconstruction algorithms, a 2.75-fold enhanced depth of field and 2-time better spatial resolution in comparison with conventional integral microscopy is reported. Our claims are supported by theoretical analysis and experimental images of a resolution test target, cotton fibers, and in-vivo 3D-imaging of biological specimens. PMID:29359107

Scanning SQUID Microscope and its Application in Detecting Weak Currents

NASA Astrophysics Data System (ADS)

Zhong, Chaorong; Li, Fei; Zhang, Fenghui; Ding, Hongsheng; Luo, Sheng; Lin, Dehua; He, Yusheng

A scanning SQUID microscope based on HTS dc SQUID has been developed. One of the applications of this microscope is to detect weak currents inside the sample. Considering that what being detected by the SQUID is the vertical component of the magnetic field on a plan where the SQUID lies, whereas the current which produces the magnetic field is actually located in a plan below the SQUID, a TWO PLAN model has been established. In this model Biot-Savart force laws and Fourier transformation were used to inverse the detected magnetic field into the underneath weak current. It has been shown that the distance between the current and the SQUID and the noise ratio of the experimental data have significant effects on the quality of the inverse process.

Loading of halloysite nanotubes with BSA, α-Lac and β-Lg: a Fourier transform infrared spectroscopic and thermogravimetric study

NASA Astrophysics Data System (ADS)

Duce, Celia; Della Porta, Valentina; Bramanti, Emilia; Campanella, Beatrice; Spepi, Alessio; Tiné, Maria Rosaria

2017-02-01

Halloysite nanotubes (HNTs) are considered as ideal materials for biotechnological and medical applications. An important feature of halloysite is that it has a different surface chemistry on the inner and outer sides of the tubes. This property means that negatively-charged molecules can be selectively loaded inside the halloysite nanoscale its lumen. Loaded HNTs can be used for the controlled or sustained release of proteins, drugs, bioactive molecules and other agents. We studied the interaction between HNTs and bovine serum albumin, α lactalbumin and β -lactoglobulin loaded into HTNs using Fourier transform infrared spectroscopy and thermogravimetry. These techniques enabled us to study the protein conformation and thermal stability, respectively, and to estimate the amount of protein loaded into the HNTs. TEM images confirmed the loading of proteins into HTNs.

Mathematical and information-geometrical entropy for phenomenological Fourier and non-Fourier heat conduction

NASA Astrophysics Data System (ADS)

Li, Shu-Nan; Cao, Bing-Yang

2017-09-01

The second law of thermodynamics governs the direction of heat transport, which provides the foundational definition of thermodynamic Clausius entropy. The definitions of entropy are further generalized for the phenomenological heat transport models in the frameworks of classical irreversible thermodynamics and extended irreversible thermodynamics (EIT). In this work, entropic functions from mathematics are combined with phenomenological heat conduction models and connected to several information-geometrical conceptions. The long-time behaviors of these mathematical entropies exhibit a wide diversity and physical pictures in phenomenological heat conductions, including the tendency to thermal equilibrium, and exponential decay of nonequilibrium and asymptotics, which build a bridge between the macroscopic and microscopic modelings. In contrast with the EIT entropies, the mathematical entropies expressed in terms of the internal energy function can avoid singularity paired with nonpositive local absolute temperature caused by non-Fourier heat conduction models.

Novel Slide-Ring Material/Natural Rubber Composites with High Damping Property

PubMed Central

Wang, Wencai; Zhao, Detao; Yang, Jingna; Nishi, Toshio; Ito, Kohzo; Zhao, Xiuying; Zhang, Liqun

2016-01-01

A novel class of polymers called “slide-ring” (SR) materials with slideable junctions were used for high damping composites for the first time. The SR acts as the high damping phase dispersed in the natural rubber (NR) matrix, and epoxidized natural rubber (ENR) acts as the compatibilizer. The morphological, structural, and mechanical properties of the composites were investigated by atomic force microscope (AFM), transmission electron microscope (TEM), dynamic mechanical thermal analyzer (DMTA), rubber processing analyzer (RPA), and tensile tester. AFM and TEM results showed that the SR phase was uniformly dispersed in the composites, in a small size that is a function of ENR. DMTA and RPA results showed that the damping factor of the composites is much higher than that of NR, especially at room temperatures. Stretch hysteresis was used to study the energy dissipation of the composites at large strains. The results showed that SR and ENR can significantly improve the dissipation efficiency at strains lower than 200% strain. Wide-angle X-ray diffraction was used to study the strain-induced crystallization of the composites. The results indicated that the impact of the SR on the crystallization of NR is mitigated by the insulating effect of ENR. PMID:26949077

Effect of isovalent dopants on photodegradation ability of ZnS nanoparticles

NASA Astrophysics Data System (ADS)

Khaparde, Rohini; Acharya, Smita

2016-06-01

Isovalent (Mn, Cd, Cu, Co)-doped-ZnS nanoparticles having size vary in between 2 to 5 nm are synthesized by co-precipitation route. Their photocatalytic activity for decoloration of Cango Red and Malachite Green dyes is tested in visible radiation under natural conditions. Structural and morphological features of the samples are investigated by X-ray diffraction, Raman spectroscopy, Scanning Electron Microscope (SEM), Transmission Electron Microscope (TEM) and UVsbnd Vis spectrometer. Single phase zinc blende structure of as-synthesized undoped and doped-ZnS is confirmed by XRD and revealed by Rietveld fitting. SEM and TEM images show ultrafine nanoparticles having size in the range of 2 to 5 nm. UV-Vis absorption spectra exhibit blue shift in absorption edge of undoped and doped ZnS as compared to bulk counterpart. The photocatalytic activity as a function of dopant concentration and irradiation time is systematically studied. The rate of de-coloration of dyes is detected by UVsbnd Vis absorption spectroscopy and organic dye mineralization is confirmed by table of carbon (TOC) study. The photocatalytic activity of Mn-doped ZnS is highest amongst all dopants; however Co as a dopant is found to reduce photocatalytic activity than pure ZnS.

High fluence swift heavy ion structure modification of the SiO2/Si interface and gate insulator in 65 nm MOSFETs

NASA Astrophysics Data System (ADS)

Ma, Yao; Gao, Bo; Gong, Min; Willis, Maureen; Yang, Zhimei; Guan, Mingyue; Li, Yun

2017-04-01

In this work, a study of the structure modification, induced by high fluence swift heavy ion radiation, of the SiO2/Si structures and gate oxide interface in commercial 65 nm MOSFETs is performed. A key and novel point in this study is the specific use of the transmission electron microscopy (TEM) technique instead of the conventional atomic force microscope (AFM) or scanning electron microscope (SEM) techniques which are typically performed following the chemical etching of the sample to observe the changes in the structure. Using this method we show that after radiation, the appearance of a clearly visible thin layer between the SiO2 and Si is observed presenting as a variation in the TEM intensity at the interface of the two materials. Through measuring the EDX line scans we reveal that the Si:O ratio changed and that this change can be attributed to the migration of the Si towards interface after the Si-O bond is destroyed by the swift heavy ions. For the 65 nm MOSFET sample, the silicon substrate, the SiON insulator and the poly-silicon gate interfaces become blurred under the same irradiation conditions.

On the Progress of Scanning Transmission Electron Microscopy (STEM) Imaging in a Scanning Electron Microscope.

PubMed

Sun, Cheng; Müller, Erich; Meffert, Matthias; Gerthsen, Dagmar

2018-04-01

Transmission electron microscopy (TEM) with low-energy electrons has been recognized as an important addition to the family of electron microscopies as it may avoid knock-on damage and increase the contrast of weakly scattering objects. Scanning electron microscopes (SEMs) are well suited for low-energy electron microscopy with maximum electron energies of 30 keV, but they are mainly used for topography imaging of bulk samples. Implementation of a scanning transmission electron microscopy (STEM) detector and a charge-coupled-device camera for the acquisition of on-axis transmission electron diffraction (TED) patterns, in combination with recent resolution improvements, make SEMs highly interesting for structure analysis of some electron-transparent specimens which are traditionally investigated by TEM. A new aspect is correlative SEM, STEM, and TED imaging from the same specimen region in a SEM which leads to a wealth of information. Simultaneous image acquisition gives information on surface topography, inner structure including crystal defects and qualitative material contrast. Lattice-fringe resolution is obtained in bright-field STEM imaging. The benefits of correlative SEM/STEM/TED imaging in a SEM are exemplified by structure analyses from representative sample classes such as nanoparticulates and bulk materials.

New Developments in Cathodoluminescence Spectroscopy for the Study of Luminescent Materials

PubMed Central

den Engelsen, Daniel; Fern, George R.; Harris, Paul G.; Ireland, Terry G.; Silver, Jack

2017-01-01

Herein, we describe three advanced techniques for cathodoluminescence (CL) spectroscopy that have recently been developed in our laboratories. The first is a new method to accurately determine the CL-efficiency of thin layers of phosphor powders. When a wide band phosphor with a band gap (Eg > 5 eV) is bombarded with electrons, charging of the phosphor particles will occur, which eventually leads to erroneous results in the determination of the luminous efficacy. To overcome this problem of charging, a comparison method has been developed, which enables accurate measurement of the current density of the electron beam. The study of CL from phosphor specimens in a scanning electron microscope (SEM) is the second subject to be treated. A detailed description of a measuring method to determine the overall decay time of single phosphor crystals in a SEM without beam blanking is presented. The third technique is based on the unique combination of microscopy and spectrometry in the transmission electron microscope (TEM) of Brunel University London (UK). This combination enables the recording of CL-spectra of nanometre-sized specimens and determining spatial variations in CL emission across individual particles by superimposing the scanning TEM and CL-images. PMID:28772671

Structural and optical studies on spin coated ZnO-graphene conjugated thin films

NASA Astrophysics Data System (ADS)

Srinatha, N.; Angadi, Basavaraj; Son, D. I.; Choi, W. K.

2018-05-01

ZnO-Graphene conjugated thin films were prepared using spin coating technique for different spin rates. Prior to the deposition, ZnO-Graphene nanoparticles were synthesized and their particle size and conjugation was studied through Transmission electron microscope (TEM). The deposited films were characterized using grazing incidence x-ray diffractometer (GIXRD), atomic force microscope (AFM) and UV-Visible spectrometer for their crystallinity, surface topographic features and optical properties. GIXRD patterns confirms the presence of both ZnO and Graphene related crystalline peaks supports the TEM results, which shows the quasi core-shell type conjugation of ZnO-Graphene particles. The crystallinity as well as thickness of the films found to decrease with increase of spin rate. AFM results reveal the uniform, smooth and homogeneity of films and also good adhesivity of ZnO-Graphene with glass substrates. No significant change in the transmittance and absorption with spin rate is observed, while the band gap energy found to decrease due to the reduction in the thickness of the films and conjugation of ZnO-Graphene. All films exhibit˜90 % transmittance in the visible wavelength region, could be potential candidates for optoelectronics and transparent conducting oxide (TCO) applications.

Lights Will Guide You : Sample Preparation and Applications for Integrated Laser and Electron Microscopy

NASA Astrophysics Data System (ADS)

Karreman, M. A.

2013-03-01

Correlative microscopy is the combined use of two different forms of microscopy in the study of a specimen, allowing for the exploitation of the advantages of both imaging tools. The integrated Laser and Electron Microscope (iLEM), developed at Utrecht University, combines a fluorescence microscope (FM) and a transmission electron microscope (TEM) in a single set-up. The region of interest in the specimen is labeled or tagged with a fluorescent probe and can easily be identified within a large field of view with the FM. Next, this same area is retraced in the TEM and can be studied at high resolution. The iLEM demands samples that can be imaged with both FM and TEM. Biological specimen, typically composed of light elements, generate low image contrast in the TEM. Therefore, these samples are often ‘contrasted’ with heavy metal stains. FM, on the other hand, images fluorescent samples. Sample preparation for correlative microscopy, and iLEM in particular, is complicated by the fact that the heavy metals stains employed for TEM quench the fluorescent signal of the probe that is imaged with FM. The first part of this thesis outlines preparation procedures for biological material yielding specimen that can be imaged with the iLEM. Here, approaches for the contrasting of thin sections of cells and tissue are introduced that do not affect the fluorescence signal of the probe that marks the region of interest. Furthermore, two novel procedures, VIS2FIXH and VIS2FIX­FS are described that allow for the chemical fixation of thin sections of cryo-immobilized material. These procedures greatly expedite the sample preparation process, and open up novel possibilities for the immuno-labeling of difficult antigens, eg. proteins and lipids that are challenging to preserve. The second part of this thesis describes applications of iLEM in research in the field of life and material science. The iLEM was employed in the study of UVC induced apoptosis (programmed cell death) of human umbilical vein endothelial cells. A novel, RNA containing body was identified in the nuclei of cells going through the various stages of the apoptotic process. Furthermore, we demonstrated the potential of iLEM in the study of Facio Scapulo Humeral Dystrophy (FSHD), the third most common form of inherited muscular dystrophy. In this study, diseased cells are identified based on the immuno-labeling of proteins associated with FSHD pathology. In the field of heterogeneous catalysis, a structural and functional characterization of Fluid Catalytic Cracking (FCC) particles was performed with iLEM. FCC particles are employed in petrochemical industry, where they catalyze the breakdown of large molecules in crude oil fractions into functional products with lower molecular weight, like gasoline. The catalytic sites in the FCC particles were selectively stained with a fluorescent probe, and next their structure was investigated with TEM. The iLEM allowed for the identification and characterization of catalytically active areas in the FCC particles. Furthermore, a unique study of the deactivation processes taking place in an industrial FCC unit was performed by analyzing a sample derived from a FCC reactor

Theory of the spatial resolution of (scanning) transmission electron microscopy in liquid water or ice layers.

PubMed

de Jonge, Niels

2018-04-01

The sample dependent spatial resolution was calculated for transmission electron microscopy (TEM) and scanning TEM (STEM) of objects (e.g., nanoparticles, proteins) embedded in a layer of liquid water or amorphous ice. The theoretical model includes elastic- and inelastic scattering, beam broadening, and chromatic aberration. Different contrast mechanisms were evaluated as function of the electron dose, the detection angle, and the sample configuration. It was found that the spatial resolution scales with the electron dose to the -1/4th power. Gold- and carbon nanoparticles were examined in the middle of water layers ranging from 0.01--10 µm thickness representing relevant classes of experiments in both materials science and biology. The optimal microscope settings differ between experimental configurations. STEM performs the best for gold nanoparticles for all layer thicknesses, while carbon is best imaged with phase-contrast TEM for thin layers but bright field STEM is preferred for thicker layers. The resolution was also calculated for a water layer enclosed between thin membranes. The influence of chromatic aberration correction for TEM was examined as well. The theory is broadly applicable to other types of materials and sample configurations. Copyright © 2018 Elsevier B.V. All rights reserved.

Ultra structural changes occurring in duct ectasia and periductal mastitis and their significance in etiopathogenesis.

PubMed

Ramalingam, Kirithiga; Vuthaluru, Seenu; Srivastava, Anurag; Dinda, Amit Kumar; Dhar, Anita

2017-01-01

Duct ectasia (DE) and periductal mastitis (PDM) are the most common benign breast conditions seen in women. The etiopathogenesis of these entities is still not clear and most of the theories regarding the causation are based on the histological features as seen on light microscopy. The ultramicroscopic features associated with these conditions that may give more insight to the etiopathogenesis are unknown. To study the ultrastructural changes occurring in mammary duct cones in patients with DE and PDM using Transmission Electron Microscopic (TEM). Major ducts removed by radical duct excision from 21 patients with final histopathological diagnosis of DE and PDM were subjected to TEM study with 2 normal duct samples as controls. The TEM features of DE were denudation of the epithelial cells with focal loss of microvilli, widening of the inter-epithelial junctions with focal disruption of the T bars, periductal collagenisation without inflammation, and features suggestive of Epithelial Mesenchymal Transition (EMT). PDM features are intact epithelial lining with proliferative epithelium and periductal collagenisation with inflammation. Based on the TEM findings, we suggest that DE and PDM are two different entities. EMT a novel finding observed in DE in this study.

Ultra structural changes occurring in duct ectasia and periductal mastitis and their significance in etiopathogenesis

PubMed Central

Ramalingam, Kirithiga; Vuthaluru, Seenu; Srivastava, Anurag; Dinda, Amit Kumar; Dhar, Anita

2017-01-01

Introduction Duct ectasia (DE) and periductal mastitis (PDM) are the most common benign breast conditions seen in women. The etiopathogenesis of these entities is still not clear and most of the theories regarding the causation are based on the histological features as seen on light microscopy. The ultramicroscopic features associated with these conditions that may give more insight to the etiopathogenesis are unknown. Aim To study the ultrastructural changes occurring in mammary duct cones in patients with DE and PDM using Transmission Electron Microscopic (TEM). Method Major ducts removed by radical duct excision from 21 patients with final histopathological diagnosis of DE and PDM were subjected to TEM study with 2 normal duct samples as controls. Results The TEM features of DE were denudation of the epithelial cells with focal loss of microvilli, widening of the inter-epithelial junctions with focal disruption of the T bars, periductal collagenisation without inflammation, and features suggestive of Epithelial Mesenchymal Transition (EMT). PDM features are intact epithelial lining with proliferative epithelium and periductal collagenisation with inflammation. Conclusions Based on the TEM findings, we suggest that DE and PDM are two different entities. EMT a novel finding observed in DE in this study. PMID:28273122

Surface phenomenon in Electrochemical Systems

NASA Astrophysics Data System (ADS)

Gupta, Tanya

Interfaces play a critical role in the performance of electrochemical systems. This thesis focusses on interfaces in batteries and covers aspects of interfacial morphologies of metal anodes, including Silicon, Lithium and Zinc. Growth and cycling of electrochemically grown Lithium and Zinc metal structures is investigated. A new morphology of Zinc, called Hyper Dendritic Zinc is introduced. It is cycled against Prussian Blue Analogues and is shown to improve the performance of this couple significantly. Characterization of materials is done using various electron microscopy techniques ranging from Low Energy Electron Microscope (LEEM), to high energy Transmission Electron Microscope (TEM). LEEM is used for capturing subtle surface phenomenon occurring during epitaxial process of electrolyte on anode. The system studied is Silicon (100) during Chemical Vapor Deposition of Ethylene Carbonate. A strain driven relaxation theory is modeled to explain the unusual restructuring of Si substrate. The other extreme, TEM, is often used to study electrochemical processes, without clear understanding of how the high-energy electron beam can influence the sample under investigation. Here, we study the radiolysis in liquid cell TEM and emphasize on the enhancement of radiation dose at interfaces of the liquid due to generation of secondary and backscattered electrons from adjoining materials. It is shown that this effect is localized in a 10 nm region around the interface and can play a dominating role if there is an interface of liquid with heavy metals like Gold and Platinum which are frequently used as electrode materials. This analysis can be used to establish guidelines for experimentalists to follow, for accurate interpretation of their results.

Influence of calcinated and non calcinated nanobioglass particles on hardness and bioactivity of sol-gel-derived TiO2-SiO2 nano composite coatings on stainless steel substrates.

PubMed

Dadash, Mohammad Saleh; Karbasi, Saeed; Esfahani, Mojtaba Nasr; Ebrahimi, Mohammad Reza; Vali, Hojatollah

2011-04-01

Thick films of calcinated and non calcinated nanobioglass (NBG)-titania composite coatings were prepared on stainless steel substrates by alkoxide sol-gel process. Dip-coating method was used for the films preparation. The morphology, structure and composition of the nano composite films were evaluated using environmental scanning electron microscope, X-ray diffraction and Fourier transform infrared spectroscope. The SEM investigation results showed that prepared thick NBG-titania films are smooth and free of macrocracking, fracture or flaking. The grain size of these films was uniform and nano scale (50-60 nm) which confirmed with TEM. Also FTIR confirmed the presence of Si-O-Si bands on the calcinated NBG-titania films. The hardness of the prepared films (TiO(2)-calcinated NBG and TiO(2)-Non calcinated NBG) was compared by using micro hardness test method. The results verified that the presence of calcinated NBG particles in NBG-titania composite enhanced gradually the mechanical data of the prepared films. The in vitro bioactivity of these films was discussed based on the analysis of the variations of Ca and P concentrations in the simulated body fluid (SBF) and their surface morphologies against immersion time. Surface morphology and Si-O-Si bands were found to be of great importance with respect to the bioactivity of the studied films. The results showed that calcinated NBG-titania films have better bioactivity than non calcinated NBG-titania films.

Surface charge-switchable polymeric magnetic nanoparticles for the controlled release of anticancer drug.

PubMed

Shen, Jian-Min; Yin, Tao; Tian, Xiao-Zhu; Gao, Fei-Yun; Xu, Shuang

2013-08-14

We develop paclitaxel (PTX) and magnetic nanoparticles (MNPs) coencapsulated, surface charge-switchable, thermosensitive poly(d,l-lactic-co-glycolic acid)-l-lysine-d-galactose (PTX-MNP-PLGA-Lys-Gal) NPs for the controlled release of the anticancer drug. The novel dual signal-responsive nanovehicle is formulated to shield off target at pH 7.4 but bind avidly to tumor cells in acidity, alleviating toxicity and side effects of the drug to normal tissues. The mechanism involves pH-sensitive NPs surface charge switching by the deblocking process of galactose molecules followed by protonation of ε-NH2 in lysine residue at acidic pH. Magnetic hyperthermia under near infrared (NIR) irradiation induced the contraction of PTX-MNP-PLGA-Lys-Gal NPs and, in turn, triggered burst release of PTX. Transmission electron microscopy (TEM), fluorescence microscope analyses, Fourier transform infrared (FTIR), X-ray diffraction (XRD), vibrating sample magnetometer (VSM), dynamic light scattering (DLS), and ξ-potential analyses were performed to characterize physicochemical properties of the as-prepared NPs. The size range of the globule PTX-MNP-PLGA-Lys-Gal NPs after being prescreened was from 130 to 150 nm under simulated physiological medium. The high encapsulation efficiencies of MNPs and PTX were obtained, reaching 85 and 78 wt % for PTX-MNP-PLGA-Lys-Gal NPs, respectively. The tumor inhibitory rate of 78.8% reflected that the resulting NPs could be promising to treat cancer by specific binding and targeting release drug to tumor.

Synthesis and characterization of hydroxyapatite nanoparticles impregnated on apple pomace to enhanced adsorption of Pb(II), Cd(II), and Ni(II) ions from aqueous solution.

PubMed

Chand, Piar; Pakade, Yogesh B

2015-07-01

Hydroxyapatite nanoparticles were synthesized, characterized, and impregnated onto apple pomace surface (HANP@AP) for efficient removal of Pb(II), Cd(II), and Ni(II) ions from water. HANP@AP was characterized by Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), energy-dispersive spectroscopy (EDS), transmission electron microscope (TEM), X-ray diffraction (XRD), and surface area analysis. Batch sorption studies were carried out to investigate the influence of different parameters as amount of dose (g), pH, time (min), and initial concentration (mg L(-1)) on adsorption process. Experimental kinetic data followed pseudo-second-order model and equilibrium data well fitted to Langmuir adsorption model with maximum adsorption capacities of 303, 250, and 100 mg g(-1) for Pb(II), Cd(II), and Ni(II) ions, respectively. Competitive adsorption of Pb(II), Cd(II), and Ni(II) ions in presences of each other was studied to evaluate the removal efficiency of HANP@AP against multi metal-loaded water. HANP@AP was successfully applied to real industrial wastewater with 100 % removal of all three metal ions even at high concentration. HANP@AP could be recycled for four, four, and three cycles in case of Pb(II), Cd(II) and Ni(II), respectively. The study showed that HANP@AP is fast, cost effective, and environmental friendly adsorbent for removal of Pb(II), Cd(II), and Ni(II) ions from real industrial wastewater.

Investigate the ultrasound energy assisted adsorption mechanism of nickel(II) ions onto modified magnetic cobalt ferrite nanoparticles: Multivariate optimization.

PubMed

Mehrabi, Fatemeh; Alipanahpour Dil, Ebrahim

2017-07-01

In present study, magnetic cobalt ferrite nanoparticles modified with (E)-N-(2-nitrobenzylidene)-2-(2-(2-nitrophenyl)imidazolidine-1-yl) ethaneamine (CoFe 2 O 4 -NPs-NBNPIEA) was synthesized and applied as novel adsorbent for ultrasound energy assisted adsorption of nickel(II) ions (Ni 2+ ) from aqueous solution. The prepared adsorbent characterized by Fourier transforms infrared spectroscopy (FT-IR), transmission electron microscope (TEM), vibrating sample magnetometer (VSM) and X-ray diffraction (XRD). The dependency of adsorption percentage to variables such as pH, initial Ni 2+ ions concentration, adsorbent mass and ultrasound time were studied with response surface methodology (RSM) by considering the desirable functions. The quadratic model between the dependent and independent variables was built. The proposed method showed good agreement between the experimental data and predictive value, and it has been successfully employed to adsorption of Ni 2+ ions from aqueous solution. Subsequently, the experimental equilibrium data at different concentration of Ni 2+ ions and 10mg amount of adsorbent mass was fitted to conventional isotherm models like Langmuir, Freundlich, Tempkin, Dubinin-Radushkevich and it was revealed that the Langmuir is best model for explanation of behavior of experimental data. In addition, conventional kinetic models such as pseudo-first and second-order, Elovich and intraparticle diffusion were applied and it was seen that pseudo-second-order equation is suitable to fit the experimental data. Copyright © 2016 Elsevier B.V. All rights reserved.

Studies on magnetic properties of chemically synthesized crystalline calcium ferrite nanoparticles

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

Debnath, A., E-mail: debnathanimesh@gmail.com; Bera, A.; Saha, B.

Spinel-type ferrites have taken a very important role for modern electronic industry. Most of these ferrites exhibit low-loss dielectric properties, high resistivity, low eddy current and also high temperature ferromagnetism. Calcium ferrite is one such important metal oxide which is environmentally safe, chemically stable, low cost and greatly abundant. This outstanding material of calcium ferrite is synthesized by a simple chemical precipitation method using NaOH as the precipitating agent. Ferric chloride anhydrous (FeCl{sub 3}) and Calcium chloride dihydrate (CaCl{sub 2}.2H{sub 2}O) were used as iron and calcium sources respectively. The samples were heated at 200°C for 8h to obtain homogeneousmore » powder of Calcium ferrite. The powders were characterized by using X-ray diffraction (XRD), field emission scanning electron microscope (FESEM), Transmission electrical microscopy (TEM), and Fourier transform infrared spectroscopic (FTIR) measurements. The polycrystalline nature of the sample was confirmed by X-ray diffraction study. The magnetic properties of the sample were investigated by vibrating sample magnetometer (VSM) measurements. Magnetization curve of the prepared sample depicts that as synthesized calcium ferrite nanoparticles have saturation magnetic moment of 1.74 emu/g and the coercivity of 35.08 Oe with superparamagnetic behavior. The synthesized calcium ferrite nanoparticles with such magnetic properties will be a candidate material for different applications in electronics and exploring its functionality in the field of recently developing semiconductor device physics and spintronics.« less

Synthesis colloidal Kyllinga brevifolia-mediated silver nanoparticles at different temperature for methylene blue removal

NASA Astrophysics Data System (ADS)

Isa, Norain; Sarijo, Siti Halimah; Aziz, Azizan; Lockman, Zainovia

2017-09-01

Metallic nanoparticles are well known of having wide applications in various fields such as, catalysis, electronics, energy, chemistry and medicine due to its unique physico-chemical properties. In this study, nanocatalyst Kyllinga brevifolia-mediated silver nanoparticles (AgNPs) were prepared by reduction of silver nitrate using aqueous extract of Kyllinga brevifolia at different temperature. The formations of AgNPs were monitored using UV-visible spectroscopy. Transmission electron microscope (TEM) results reveal that the AgNPs well dispersed with average particle size are 22.34 and 6.73 nm for synthesized at room temperature and cold temperature respectively. The biomolecules present in the Kyllinga brevifolia aqueous extract responsible for the formation of AgNPs were identified using Fourier transform infrared (FTIR). Our AgNPs performed excellent catalytic activity in degradation of methylene blue (MB) dyes via electron relay effect. MB is toxic to ecological system and also has carcinogenic properties. The AgNPs nanocatalysts synthesized in this study are highly dispersed, quasi-spherical and due to their size in nanoscale, they have shown effectiveness for degradation of MB dyes. More importantly, our AgNPs were prepared using biomolecules as capping and reducing agent, which make our product "greener" than available AgNPs that are commonly prepared using hydrazine and borohydride; which are harmful substances to human and environment. Not only the AgNPs can act as nanocatalyst for degradation of MB, they can also be expected to degrade other types of toxic dyes used in textiles industry.

Fabrication of CuO-doped catalytic material containing zeolite synthesized from red mud and rice husk ash for CO oxidation

NASA Astrophysics Data System (ADS)

Hieu Do Thi, Minh; Thinh Tran, Quoc; Nguyen, Tri; Van Nguyen Thi, Thuy; Huynh, Ky Phuong Ha

2018-06-01

In this study a series of the CuO-doped materials containing zeolite with varying CuO contents were synthesized from red mud (RM) and rice husk ash (RHA). The rice husk ash/red mud with the molar ratio of , and being 1.8, 2.5 and 60, respectively, were maintained during the synthetic process of materials. The characteristic structure samples were analyzed by x-ray diffraction (XRD), Fourier transformed infrared spectroscopy (FTIR), scanning electron microscopy (SEM), transmission electron microscope (TEM), Brunauer–Emmett–Teller (BET) surface area and H2 temperature program reduction (H2-TPR). The catalytic activity of samples was evaluated in CO oxidation reaction in a microflow reactor at temperature range 200 °C–350 °C. The obtained results showed that all synthetic samples there exist the A-type zeolites with the average crystal size of 15–20 nm, the specific surface area of , and pore volume of . The material synthesized from RM and RHA with the zeolite structure (ZRM, undoped CuO) could also oxidize CO completely at 350 °C, and its activity was increase significantly when doped with CuO. CuO-doped materials with the zeolite structure exhibited excellent catalytic activity in CO oxidation. The ZRM sample loading 5 wt% CuO with particle nanosize about 10–30 nm was the best one for CO oxidation with complete conversion temperature at 275 °C.

One-pot synthesis of dextran decorated reduced graphene oxide nanoparticles for targeted photo-chemotherapy.

PubMed

Hu, Yanfang; He, Liang; Ding, Jianxun; Sun, Diankui; Chen, Li; Chen, Xuesi

2016-06-25

Graphene-based nanocarriers show great potential in photo-chemotherapy, however, to prepare desired reduced graphene oxide (rGO) nanoparticles in a facile way is still a challenge. Herein, a novel strategy has been presented to prepare rGO nanoparticle using dextran (Dex) as a reducing agent. In this strategy, Dex was directly conjugated on rGO by hydrogen bond and then self-assemble to form rGO/Dex nanoparticles. After decorated by dextran, rGO-based nanoparticles not only show excellent biocompatibility but also can load anticancer drug for photo-chemotherapy. The data of fourier transform infrared (FT-IR) analysis, Raman spectrum analysis, thermos-gravimetric analysis (TGA), X-ray photoelectron spectroscopy (XPS), the transmission electron microscope (TEM) image and dynamic light scattering (DLS) measurements powerfully proved that the stable rGO-based nanoparticles with desired nanosize have been successfully prepared. To verify the photo-chemotherapy, anticancer drug, doxorubicin (DOX), has been loaded on rGO/Dex nanoparticles (rGO/DOX/Dex). And RGD, a kind of oligopeptide which can improve the intracellular uptake by αvβ3 recognition, also has been introduced (rGO/DOX/RDex). Compared with single chemotherapy, rGO/DOX/Dex and rGO/DOX/RDex combining the local specific chemotherapy and external near-infrared (NIR) photo-thermal therapy show higher therapeutic efficacy, endowing the desired rGO-based nanoparticle with great potential for cancer treatments. Copyright © 2016 Elsevier Ltd. All rights reserved.

Characterization of silver/polystyrene nanocomposites prepared by in situ bulk radical polymerization

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

Vukoje, Ivana D., E-mail: ivanav@vinca.rs; Vodnik, Vesna V., E-mail: vodves@vinca.rs; Džunuzović, Jasna V., E-mail: jasnav2002@googlemail.com

2014-01-01

Graphical abstract: - Highlights: • Synthesis and characterization of polystyrene nanocomposites based on Ag nanoparticles. • The glass transition temperature decreased in nanocomposites with respect to the pure polymer. • Resistance of the polymer to thermal degradation enhanced with Ag nanoparticles content. - Abstract: Nanocomposites (NCs) with different content of silver nanoparticles (Ag NPs) embeded in polystyrene (PS) matrix were prepared by in situ bulk radical polymerization. The nearly monodisperse Ag NPs protected with oleylamine were synthesized via organic solvo-thermal method and further used as a filler. The as-prepared spherical Ag NPs with diameter of 7.0 ± 1.5 nm weremore » well dispersed in the PS matrix. The structural properties of the resulting Ag/PS NCs were characterized by transmission electron microscope (TEM) and Fourier transform infrared (FTIR) spectroscopy, while optical properties were characterized using optical absorption measurements. The gel permeation chromatography (GPC) measurements showed that the presence of Ag NPs stabilized with oleylamine has no influence on the molecular weight and polydispersity of the PS matrix. The influence of silver content on the thermal properties of Ag/PS NCs was investigated by thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC). The results indicated that resistance of PS to thermal degradation was improved upon incorporation of Ag NPs. The Ag/PS NCs have lower glass transition temperatures than neat PS because loosely packed oleylamine molecules at the interface caused the increase of free volume and chain segments mobility near the surface of Ag NPs.« less

Effect of Ca substitution on some physical properties of nano-structured and bulk Ni-ferrite samples

NASA Astrophysics Data System (ADS)

Assar, S. T.; Abosheiasha, H. F.

2015-01-01

Nanoparticles of Ni1-xCaxFe2O4 (x=0.0, 0.02, 0.04, 0.06 and 0.10) were prepared by citrate precursor method. A part of these samples was sintered at 600 °C for 2 h in order to keep the particles within the nano-size while the other part was sintered at 1000 °C to let the particles to grow to the bulk size. The effect of Ca2+ ion substitution in nickel ferrite on some structural, magnetic, electrical and thermal properties was investigated. All samples were characterized by using X-ray diffraction (XRD), transmission electron microscope (TEM), Fourier transform infrared spectroscopy (FTIR) and vibrating sample magnetometer (VSM). A two probe method was used to measure the dc electrical conductivity whereas the photoacoustic (PA) technique was used to determine the thermal diffusivity of the samples. To interpret different experimental results for nano and bulk samples some cation distributions were assumed based on the VSM and XRD data. These suggested cation distributions give logical explanations for other experimental results such as the observed values of the absorption bands in FTIR spectra and the dc conductivity results. Finally, in the thermal measurements it was found that increasing the Ca2+ ion content causes a decrease in the thermal diffusivity of both nano and bulk samples. The explanation of this behavior is ascribed to the phonon-phonon scattering.

Synthesis and characterization of some metal oxide nanocrystals by microwave irradiation

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

Rashad, M.; Gaber, A.; Abdelrahim, M. A.

2013-12-16

Copper oxide and cobalt oxide (CuO, Co3O4) nanocrystals (NCs) have been successfully prepared in a short time using microwave irradiation. The resulted powders of nanocrystals (NCs) were characterized by X-ray diffraction (XRD) and transmission electron microscopy (TEM). Thermogravimetric analysis (TGA) measurements are also studied. Fourier-transform infrared (FT-IR) and UV–visible absorption spectroscopy of both kind of nanoparticels are illustrated. Optical absorption analysis indicated the direct band gap for both kinds of nanocrystals.

Diamond-Based Magnetic Imaging with Fourier Optical Processing

NASA Astrophysics Data System (ADS)

Backlund, Mikael P.; Kehayias, Pauli; Walsworth, Ronald L.

2017-11-01

Diamond-based magnetic field sensors have attracted great interest in recent years. In particular, wide-field magnetic imaging using nitrogen-vacancy (NV) centers in diamond has been previously demonstrated in condensed matter, biological, and paleomagnetic applications. Vector magnetic imaging with NV ensembles typically requires a significant applied field (>10 G ) to resolve the contributions from four crystallographic orientations, hindering studies of magnetic samples that require measurement in low or independently specified bias fields. Here we model and measure the complex amplitude distribution of NV emission at the microscope's Fourier plane and show that by modulating this collected light at the Fourier plane, one can decompose the NV ensemble magnetic resonance spectrum into its constituent orientations by purely optical means. This decomposition effectively extends the dynamic range at a given bias field and enables wide-field vector magnetic imaging at arbitrarily low bias fields, thus broadening potential applications of NV imaging and sensing. Our results demonstrate that NV-based microscopy stands to benefit greatly from Fourier optical approaches, which have already found widespread utility in other branches of microscopy.

ERDA, RBS, TEM and SEM characterization of microstructural evolution in helium-implanted Hastelloy N alloy

NASA Astrophysics Data System (ADS)

Gao, Jie; Bao, Liangman; Huang, Hefei; Li, Yan; Lei, Qiantao; Deng, Qi; Liu, Zhe; Yang, Guo; Shi, Liqun

2017-05-01

Hastelloy N alloy was implanted with 30 keV, 5 × 1016 ions/cm2 helium ions at room temperature, and subsequent annealed at 600 °C for 1 h and further annealed at 850 °C for 5 h in vacuum. Using elastic recoil detection analysis (ERDA) and transmission electron microscopy (TEM), the depth profiles of helium concentration and helium bubbles in helium-implanted Hastelloy N alloy were investigated, respectively. The diffusion of helium and molybdenum elements to surface occurred during the vacuum annealing at 850 °C (5 h). It was also observed that bubbles in molybdenum-enriched region were much larger in size than those in deeper region. In addition, it is worth noting that plenty of nano-holes can be observed on the surface of helium-implanted sample after high temperature annealing by scanning electron microscope (SEM). This observation provides the evidence for the occurrence of helium release, which can be also inferred from the results of ERDA and TEM analysis.

Scanning electron microscopy imaging of dislocations in bulk materials, using electron channeling contrast.

PubMed

Crimp, Martin A

2006-05-01

The imaging and characterization of dislocations is commonly carried out by thin foil transmission electron microscopy (TEM) using diffraction contrast imaging. However, the thin foil approach is limited by difficult sample preparation, thin foil artifacts, relatively small viewable areas, and constraints on carrying out in situ studies. Electron channeling imaging of electron channeling contrast imaging (ECCI) offers an alternative approach for imaging crystalline defects, including dislocations. Because ECCI is carried out with field emission gun scanning electron microscope (FEG-SEM) using bulk specimens, many of the limitations of TEM thin foil analysis are overcome. This paper outlines the development of electron channeling patterns and channeling imaging to the current state of the art. The experimental parameters and set up necessary to carry out routine channeling imaging are reviewed. A number of examples that illustrate some of the advantages of ECCI over thin foil TEM are presented along with a discussion of some of the limitations on carrying out channeling contrast analysis of defect structures. Copyright (c) 2006 Wiley-Liss, Inc.

In situ TEM observation of FCC Ti formation at elevated temperatures

DOE PAGES

Yu, Qian; Kacher, Josh; Gammer, Christoph; ...

2017-07-04

Pure Ti traditionally exhibits the hexagonal closed packed (HCP) crystallographic structure under ambient conditions and the body centered cubic (BCC) structure at elevated temperatures. In addition to these typical structures for Ti alloys, the presence of a face centered cubic (FCC) phase associated with thin films, interfaces, or high levels of plastic deformation has occasionally been reported. Here in this paper we show that small FCC precipitates form in freestanding thin foils during in situ transmission electron microscope (TEM) heating and we discuss the potential origins of the FCC phase in light of the in situ observations. This FCC phasemore » was found to be stable upon cooling and under ambient conditions, which allowed us to explore its mechanical properties and stability via nanomechanical in situ TEM testing. It was found that FCC platelets within the HCP matrix phase were stable under mechanical deformation and exhibited similar mechanical deformation behavior as the parent HCP phase.« less

Size distribution and volume fraction of T(1) phase precipitates from TEM images: Direct measurements and related correction.

PubMed

Dorin, Thomas; Donnadieu, Patricia; Chaix, Jean-Marc; Lefebvre, Williams; Geuser, Frédéric De; Deschamps, Alexis

2015-11-01

Transmission Electron Microscopy (TEM) can be used to measure the size distribution and volume fraction of fine scale precipitates in metallic systems. However, such measurements suffer from a number of artefacts that need to be accounted for, related to the finite thickness of the TEM foil and to the projected observation in two dimensions of the microstructure. We present a correction procedure to describe the 3D distribution of disc-like particles and apply this method to the plate-like T1 precipitates in an Al-Li-Cu alloy in two ageing conditions showing different particle morphologies. The precipitates were imaged in a High-Angular Annular Dark Field Microscope (HAADF-STEM). The corrected size distribution is further used to determine the precipitate volume fraction. Atom probe tomography (APT) is finally utilised as an alternative way to measure the precipitate volume fraction and test the validity of the electron microscopy results. Copyright © 2015 Elsevier Ltd. All rights reserved.

In situ TEM observation of FCC Ti formation at elevated temperatures

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

Yu, Qian; Kacher, Josh; Gammer, Christoph

Pure Ti traditionally exhibits the hexagonal closed packed (HCP) crystallographic structure under ambient conditions and the body centered cubic (BCC) structure at elevated temperatures. In addition to these typical structures for Ti alloys, the presence of a face centered cubic (FCC) phase associated with thin films, interfaces, or high levels of plastic deformation has occasionally been reported. Here in this paper we show that small FCC precipitates form in freestanding thin foils during in situ transmission electron microscope (TEM) heating and we discuss the potential origins of the FCC phase in light of the in situ observations. This FCC phasemore » was found to be stable upon cooling and under ambient conditions, which allowed us to explore its mechanical properties and stability via nanomechanical in situ TEM testing. It was found that FCC platelets within the HCP matrix phase were stable under mechanical deformation and exhibited similar mechanical deformation behavior as the parent HCP phase.« less

Full Waveform Modeling of Transient Electromagnetic Response Based on Temporal Interpolation and Convolution Method

NASA Astrophysics Data System (ADS)

Qi, Youzheng; Huang, Ling; Wu, Xin; Zhu, Wanhua; Fang, Guangyou; Yu, Gang

2017-07-01

Quantitative modeling of the transient electromagnetic (TEM) response requires consideration of the full transmitter waveform, i.e., not only the specific current waveform in a half cycle but also the bipolar repetition. In this paper, we present a novel temporal interpolation and convolution (TIC) method to facilitate the accurate TEM modeling. We first calculate the temporal basis response on a logarithmic scale using the fast digital-filter-based methods. Then, we introduce a function named hamlogsinc in the framework of discrete signal processing theory to reconstruct the basis function and to make the convolution with the positive half of the waveform. Finally, a superposition procedure is used to take account of the effect of previous bipolar waveforms. Comparisons with the established fast Fourier transform method demonstrate that our TIC method can get the same accuracy with a shorter computing time.

Green synthesis of gold nanoparticles using extracts of Artocarpus Lakoocha fruit and its leaves, and Eriobotrya Japonica leaves

NASA Astrophysics Data System (ADS)

Sharma, Ankita; Dhiman, Naresh; Singh, Bhanu P.; Gathania, Arvind K.

2014-04-01

Gold nanoparticles (AuNPs) synthesis is demonstrated successfully using fresh young leaves of Artocarpus Lakoocha (A. Lakoocha), fruit pulp of A. Lakoocha and loquat (Eriobotrya Japonica) leaves. We have also compared green synthesis with chemical assisted tri-n-octyl-phosphine (TOP) stabilized gold nanoparticles. Samples were characterized with transmission electron microscopy (TEM), Fourier transform infrared spectroscopy and UV-Visible spectroscopy. TEM images have shown that the average size of the particles is 15.06, 36.8 and 25.08 nm for A. Lakoocha fruits, A. Lakoocha leaves and loquat leaves assisted gold nanoparticles, respectively. Hydrogen tetrachloroaurate is reduced and AuNPs are stabilized by phenols, hydroxyls and carboxyls groups such as terpenoids, flavonoids, tannins etc, present in young leaves and fruit extracts. It was observed that green synthesis using botanical extracts is a cost effective and non- toxic way for nanoparticle preparation.

Synergistic effect of reductase and keratinase for facile synthesis of protein-coated gold nanoparticles.

PubMed

Gupta, Sonali; Singh, Surinder P; Singh, Rajni

2015-05-01

We have synthesized gold nanoparticles (GNPs) using chicken feathers (poultry waste) and Bacillus subtilis RSE163. Disulfide reductase and keratinase produced by Bacillus subtilis during the degradation of chicken feather has been used to reduce Au(3+) from HAuCl4 precursor to produce gold nanoparticles. The synthesized biogenic GNPs were characterized by UV-visible spectroscopy, transmission electron microscopy (TEM), and zeta potential measurements. Fourier transform infrared (FTIR) spectroscopy indicated the presence of protein capping on synthesized GNPs, imparting multifunctionality to the GNP surface. Furthermore, the nontoxic nature of biogenic GNPs was insured by interaction with Escherichia coli (ATCC11103), where TEM images and enhancement of growth rate of E. coli in log phase signified their nontoxic nature. The results indicate that the synthesis of biocompatible GNPs using poultry waste may find potential applications in drug delivery and sensing.

Microstructural, optical and electrical transport properties of Cd-doped SnO2 nanoparticles

NASA Astrophysics Data System (ADS)

Ahmad, Naseem; Khan, Shakeel; Mohsin Nizam Ansari, Mohd

2018-03-01

We have successfully investigated the structural, optical and dielectric properties of Cd assimilated SnO2 nanoparticles synthesized via very convenient precipitation route. The structural properties were studied by x-ray diffraction method (XRD) and Fourier Transform Infrared (FTIR) Spectroscopy. As-synthesized samples in the form of powder were examined for its morphology and average particle size by Transmission electron microscopy (TEM). The optical properties were studied by diffuse reflectance spectroscopy. Dielectric properties such that complex dielectric constant and ac conductivity were investigated by LCR meter. Average crystallite size calculated by XRD and average particle size obtained from TEM were found to be consistent and below 50 nm for all samples. The optical band gap of as-synthesized powder samples from absorption study was found in the range of 3.76 to 3.97 eV. The grain boundary parameters such that Rgb, Cgb and τ were evaluated using impedance spectroscopy.

Biocatalytic and antibacterial visualization of green synthesized silver nanoparticles using Hemidesmus indicus.

PubMed

Latha, M; Sumathi, M; Manikandan, R; Arumugam, A; Prabhu, N M

2015-05-01

In the present investigation, we described the green synthesis of silver nanoparticles using plant leaf extract of Hemidesmus indicus. The synthesized silver nanoparticles were characterized by UV-visible spectroscopy, fourier transform infra-red spectroscopy (FTIR), X-ray diffraction (XRD), transmission electron microscopy (TEM) and energy dispersive X-ray spectroscopy (EDX). TEM images proved that the synthesized silver nanoparticles were spherical in shape with an average particle size of 25.24 nm. To evaluate antibacterial efficacy, bacteria was isolated from poultry gut and subjected to 16S rRNA characterization and confirmed as Shigella sonnei. The in vitro antibacterial efficacy of synthesized silver nanoparticles was studied by agar bioassay, well diffusion and confocal laser scanning microscopy (CLSM) assay. The H. indicus mediated synthesis of silver nanoparticles shows rapid synthesis and higher inhibitory activity (34 ± 0.2 mm) against isolated bacteria S. sonnei at 40 μg/ml. Copyright © 2015 Elsevier Ltd. All rights reserved.

Reusability Performance of Zinc Oxide Nanoparticles for Photocatalytic Degradation of POME

NASA Astrophysics Data System (ADS)

Zarifah Zainuri, Nur; Hanis Hayati Hairom, Nur; Abu Bakar Sidik, Dilaelyana; Misdan, Nurasyikin; Yusof, Norhaniza; Wahab Mohammad, Abdul

2018-03-01

Performance and reusability of different zinc oxide nanoparticles (ZnO-PVP and ZnO-PEG) for photocatalytic degradation of palm-mill oil effluent (POME) has been studied. The nanoparticles properties were characterised with fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD) and transmission electron microscopy (TEM). The TEM results show that ZnO-PEG nanoparticles exhibit the smaller size than ZnO-PVP with less agglomeration. It was found that ZnO-PEG shows better effectiveness than ZnO-PVP in reducing turbidity, colour and increasing the dissolved oxygen (DO). By using two types of reusability methods: (a) oven drying (b) hot water rinsing, the oven drying method portrayed the most efficient route for POME treatment. This research would be a solution to the palm oil industry for photocatalyst recovering as well as reduction of the chemical usage in order to meet the development of advanced and greener technologies.

Influence of reaction time and synthesis temperature on the physical properties of ZnO nanoparticles synthesized by the hydrothermal method

NASA Astrophysics Data System (ADS)

Wasly, H. S.; El-Sadek, M. S. Abd; Henini, Mohamed

2018-01-01

Influence of synthesis temperature and reaction time on the structural and optical properties of ZnO nanoparticles synthesized by the hydrothermal method was investigated using X-ray diffraction (XRD), high resolution transmission electron microscopy (HR-TEM), energy-dispersive X-ray, Fourier transform infra-red spectroscopy, and UV-visible and fluorescence spectroscopy. The XRD pattern and HR-TEM images confirmed the presence of crystalline hexagonal wurtzite ZnO nanoparticles with average crystallite size in the range 30-40 nm. Their energy gap determined by fluorescence was found to depend on the synthesis temperature and reaction time with values in the range 2.90-3.78 eV. Thermal analysis, thermogravimetric and the differential scanning calorimetry were used to study the thermal reactions and weight loss with heat of the prepared ZnO nanoparticles.

Non-intercalative, deoxyribose binding of boric acid to calf thymus DNA.

PubMed

Ozdemir, Ayse; Gursaclı, Refiye Tekiner; Tekinay, Turgay

2014-05-01

The present study characterizes the effects of the boric acid binding on calf thymus DNA (ct-DNA) by spectroscopic and calorimetric methods. UV-Vis absorbance spectroscopy, circular dichroism (CD) spectroscopy, transmission electron microscopy (TEM), isothermal titration calorimetry (ITC), and Fourier transform infrared (FT-IR) spectroscopy were employed to characterize binding properties. Changes in the secondary structure of ct-DNA were determined by CD spectroscopy. Sizes and morphologies of boric acid-DNA complexes were determined by transmission electron microscopy (TEM). The kinetics of boric acid binding to calf thymus DNA (ct-DNA) was investigated by isothermal titration calorimetry (ITC). ITC results revealed that boric acid exhibits a moderate affinity to ct-DNA with a binding constant (K a) of 9.54 × 10(4) M(-1). FT-IR results revealed that boric acid binds to the deoxyribose sugar of DNA without disrupting the B-conformation at tested concentrations.

Effect of acid on the aggregation of poly(ethylene xide)-poly(propylene oxide)-poly(ethylene oxide) block copolymers.

PubMed

Yang, Bin; Guo, Chen; Chen, Shu; Ma, Junhe; Wang, Jing; Liang, Xiangfeng; Zheng, Lily; Liu, Huizhou

2006-11-23

The acid effect on the aggregation of poly(ethylene oxide)-poly(propylene oxide)-poly(ethylene oxide) block copolymers EO(20)PO(70)EO(20) has been investigated by transmission electron microscopy (TEM), particle size analyzer (PSA), Fourier transformed infrared, and fluorescence spectroscopy. The critical micellization temperature for Pluronic P123 in different HCl aqueous solutions increases with the increase of acid concentration. Additionally, the hydrolysis degradation of PEO blocks is observed in strong acid concentrations at higher temperatures. When the acid concentration is low, TEM and PSA show the increase of the micelle mean diameter and the decrease of the micelle polydispersity at room temperature, which demonstrate the extension of EO corona and tendency of uniform micelle size because of the charge repulsion. When under strong acid conditions, the aggregation of micelles through the protonated water bridges was observed.

Phage Conversion for β-Lactam Antibiotic Resistance of Staphylococcus aureus from Foods.

PubMed

Lee, Young-Duck; Park, Jong-Hyun

2016-02-01

Temperate phages have been suggested to carry virulence factors and other lysogenic conversion genes that play important roles in pathogenicity. In this study, phage TEM123 in wild-type Staphylococcus aureus from food sources was analyzed with respect to its morphology, genome sequence, and antibiotic resistance conversion ability. Phage TEM123 from a mitomycin C-induced lysate of S. aureus was isolated from foods. Morphological analysis under a transmission electron microscope revealed that it belonged to the family Siphoviridae. The genome of phage TEM123 consisted of a double-stranded DNA of 43,786 bp with a G+C content of 34.06%. A bioinformatics analysis of the phage genome identified 43 putative open reading frames (ORFs). ORF1 encoded a protein that was nearly identical to the metallo-β-lactamase enzymes that degrade β-lactam antibiotics. After transduction to S. aureus with phage TEM123, the metallo-β-lactamase gene was confirmed in the transductant by PCR and sequencing analyses. In a β-lactam antibiotic susceptibility test, the transductant was more highly resistant to β-lactam antibiotics than S. aureus S133. Phage TEM123 might play a role in the transfer of β-lactam antibiotic resistance determinants in S. aureus. Therefore, we suggest that the prophage of S. aureus with its exotoxin is a risk factor for food safety in the food chain through lateral gene transfer.

Shock-produced olivine glass: First observation

USGS Publications Warehouse

Jeanloz, R.; Ahrens, T.J.; Lally, J.S.; Nord, G.L.; Christie, J.M.; Heuer, A.H.

1977-01-01

Transmission electron microscope (TEM) observations of an experimentally shock-deformed single crystal of natural peridot, (Mg0.88Fe 0.12SiO4 recovered from peak pressures of about 56 ?? 109 pascals revealed the presence of amorphous zones located within crystalline regions with a high density of tangled dislocations. This is the first reported observation ofolivine glass. The shocked sample exhibits a wide variation in the degree of shock deformation on a small scale, and the glass appears to be intimately associated with the highest density of dislocations. This study suggests that olivine glass may be formed as a result of shock at pressures above about 50 to 55 ?? 109 pascals and that further TEM observations of naturally shocked olivines may demonstrate the presence of glass.

Combustion synthesis and structural analysis of nanocrystalline nickel ferrite at low temperature regime

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

Shanmugavel, T., E-mail: gokulrajs@hotmail.com, E-mail: shanmugavelnano@gmail.com; Raj, S. Gokul, E-mail: gokulrajs@hotmail.com, E-mail: shanmugavelnano@gmail.com; Rajarajan, G.

2015-06-24

Combustion synthesis of single phase Nickel ferrite was successfully achieved at low temperature regime. The obtained powders were calcinated to increase the crystallinity and their characterization change due to calcinations is investigated in detail. Citric acid used as a chelating agent for the synthesis of nickel ferrite. Pure single phase nickel ferrites were found at this low temperature. The average crystalline sizes were measured by using powder XRD measurements. Surface morphology was investigated through Transmission Electron Microscope (TEM). Particle size calculated in XRD is compared with TEM results. Magnetic behaviour of the samples is analyzed by using Vibrating Sample Magnetometermore » (VSM). Saturation magnetization, coercivity and retentivity are measured and their results are discussed in detail.« less

A TEM analysis of nanoparticulates in a Polar ice core

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

Esquivel, E.V.; Murr, L.E

2004-03-15

This paper explores the prospect for analyzing nanoparticulates in age-dated ice cores representing times in antiquity to establish a historical reference for atmospheric particulate regimes. Analytical transmission electron microscope (TEM) techniques were utilized to observe representative ice-melt water drops dried down on carbon/formvar or similar coated grids. A 10,000-year-old Greenland ice core was melted, and representative water drops were transferred to coated grids in a clean room environment. Essentially, all particulates observed were aggregates and either crystalline or complex mixtures of nanocrystals. Especially notable was the observation of carbon nanotubes and related fullerene-like nanocrystal forms. These observations are similar withmore » some aspects of contemporary airborne particulates including carbon nanotubes and complex nanocrystal aggregates.« less

Dopant mapping in thin FIB prepared silicon samples by Off-Axis Electron Holography.

PubMed

Pantzer, Adi; Vakahy, Atsmon; Eliyahou, Zohar; Levi, George; Horvitz, Dror; Kohn, Amit

2014-03-01

Modern semiconductor devices function due to accurate dopant distribution. Off-Axis Electron Holography (OAEH) in the transmission electron microscope (TEM) can map quantitatively the electrostatic potential in semiconductors with high spatial resolution. For the microelectronics industry, ongoing reduction of device dimensions, 3D device geometry, and failure analysis of specific devices require preparation of thin TEM samples, under 70 nm thick, by focused ion beam (FIB). Such thicknesses, which are considerably thinner than the values reported to date in the literature, are challenging due to FIB induced damage and surface depletion effects. Here, we report on preparation of TEM samples of silicon PN junctions in the FIB completed by low-energy (5 keV) ion milling, which reduced amorphization of the silicon to 10nm thick. Additional perpendicular FIB sectioning enabled a direct measurement of the TEM sample thickness in order to determine accurately the crystalline thickness of the sample. Consequently, we find that the low-energy milling also resulted in a negligible thickness of electrically inactive regions, approximately 4nm thick. The influence of TEM sample thickness, FIB induced damage and doping concentrations on the accuracy of the OAEH measurements were examined by comparison to secondary ion mass spectrometry measurements as well as to 1D and 3D simulations of the electrostatic potentials. We conclude that for TEM samples down to 100 nm thick, OAEH measurements of Si-based PN junctions, for the doping levels examined here, resulted in quantitative mapping of potential variations, within ~0.1 V. For thinner TEM samples, down to 20 nm thick, mapping of potential variations is qualitative, due to a reduced accuracy of ~0.3 V. This article is dedicated to the memory of Zohar Eliyahou. Copyright © 2014 Elsevier B.V. All rights reserved.

Multi-walled carbon nanotubes decorated by platinum catalyst nanoparticles--examination and microanalysis using scanning and transmission electron microscopies.

PubMed

Guinel, M J-F; Brodusch, N; Verde-Gómez, Y; Escobar-Morales, B; Gauvin, R

2013-10-01

Carbon nanotubes (CNTs) decorated with platinum (Pt) nanoparticles (NPs) have been characterized using a cold field-emission scanning electron microscope (SEM) and a high resolution field-emission transmission electron microscope (TEM). With this particular composite material, the complementary nature of the two instruments was demonstrated. Although the long CNTs were found to be mostly bent and defective in some parts, the nucleation of Pt occurred randomly and uniformly covered the CNTs. The NPs displayed a large variation in size, were sometimes defective with twins and stacking faults, and were found to be faceted with the presence of surface steps. The shape and size of the NPs and the presence of defects may have significant consequences on the activity of the Pt catalyst material. Also, thin layers of platinum oxide were identified on the surface of some NPs. © 2013 The Authors Journal of Microscopy © 2013 Royal Microscopical Society.

Controlling dispersion of graphene nanoplatelets in aqueous solution by ultrasonic technique

NASA Astrophysics Data System (ADS)

Wang, Baomin; Jiang, Ruishuang; Song, Wanzeng; Liu, Hui

2017-08-01

The homogenous graphene nanoplatelets (GNP) suspension had been prepared through ultrasonic exfoliation in the presence of methylcellulose (MC) as dispersant. The influence of different sonication times on dispersing of aqueous GNP suspension was monitored by UV-Vis absorbance, sedimentation test, optical microscope and transmission electron microscope (TEM). The study of UV-Vis absorbance verifies that the minimum sonication time to break the 0.1 g/L concentration of bundled GNPs is 20 min; furthermore, the GNP suspension achieved the best dispersion, when sonication time increased up to 80 min. From optical microscope images of GNPs, the agglomeration of GNPs was broken by enough sonication energy, and the distribution of GNPs particles became more uniform. The dispersing mechanism had been discussed and simulated by HRTEM image. The bundled GNPs were exfoliated by cavitation effect of ultrasonic irradiation, meanwhile, the dispersant adsorbed on the surface of GNPs prevented re-entanglement by forming steric hindrance.

Acoustical nanometre-scale vibrations of live cells detected by a near-field optical setup

NASA Astrophysics Data System (ADS)

Piga, Rosaria; Micheletto, Ruggero; Kawakami, Yoichi

2007-04-01

The Scanning Near-field Optical Microscope (SNOM) is able to detect tiny vertical movement on the cell membrane in the range of only 1 nanometer or less, about 3 orders of magnitude better than conventional optical microscopes. Here we show intriguing data of cell membrane nanometer-scale dynamics associated to different phenomena of the cell’s The Scanning Near-field Optical Microscope (SNOM) is able to detect tiny vertical movement on the cell membrane in the range of only 1 nanometer or less, about 3 orders of magnitude better than conventional optical microscopes. Here we show intriguing data of cell membrane nanometer-scale dynamics associated to different phenomena of the cell’s life, such as cell cycle and cell death, on rat pheochromocytoma line PC12. Working in culture medium with alive and unperturbed samples, we could detect nanometer-sized movements; Fourier components revealed a clear distinct behavior associated to regulation of neurite outgrowth and changes on morphology after necrotic stimulus.

Novel Starch-PVA Polymer for Microparticle Preparation and Optimization Using Factorial Design Study

PubMed Central

Chattopadhyay, Helen; De, Amit Kumar; Datta, Sriparna

2015-01-01

The aim of our present work was to optimize the ratio of a very novel polymer, starch-polyvinyl alcohol (PVA), for controlled delivery of Ornidazole. Polymer-coated drug microparticles were prepared by emulsion method. Microscopic study, scanning electron microscopic study, and atomic force microscopic study revealed that the microparticles were within 10 micrometers of size with smooth spherical shape. The Fourier transform infrared spectroscopy showed absence of drug polymer interaction. A statistical 32 full factorial design was used to study the effect of different concentration of starch and PVA on the drug release profile. The three-dimensional plots gave us an idea about the contribution of each factor on the release kinetics. Hence this novel polymer of starch and polyvinyl alcohol can be utilized for control release of the drug from a targeted delivery device. PMID:27347511

Preparation and performance of broadband antireflective sub-wavelength structures on Ge substrate

NASA Astrophysics Data System (ADS)

Shen, Xiang-Wei; Liu, Zheng-Tang; Li, Yang-Ping; Lu, Hong-Cheng; Xu, Qi-Yuan; Liu, Wen-Ting

2009-01-01

Sub-wavelength structures (SWS) were prepared on Ge substrates through photolithography and reactive ion etching (RIE) technology for broadband antireflective purposes in the long wave infrared (LWIR) waveband of 8-12 μm. Topography of the etched patterns was observed using high resolution optical microscope and atomic force microscope (AFM). Infrared transmission performance of the SWS was investigated by Fourier transform infrared (FTIR) spectrometer. Results show that the etched patterns were of high uniformity and fidelity, the SWS exhibited a good broadband antireflective performance with the increment of the average transmittance which is over 8-12 μm up to 8%.

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

Gantayat, S., E-mail: subhra-gantayat@rediffmail.com; Rout, D.; Swain, S. K.

The effect of the functionalization of multiwalled carbon nanotube on the structure and electrical properties of composites was investigated. Samples based on epoxy resin with different weight percentage of MWCNTs were prepared and characterized. The interaction between MWCNT & epoxy resin was noticed by Fourier transform infrared spectroscopy (FTIR). The structure of functionalized multiwalled carbon nanotube (f-MWCNT) reinforced epoxy composite was studied by field emission scanning electron microscope (FESEM). The dispersion of f-MWCNT in epoxy resin was evidenced by high resolution transmission electron microscope (HRTEM). Electrical properties of epoxy/f-MWCNT nanocomposites were measured & the result indicated that the conductivity increasedmore » with increasing concentration of f-MWCNTs.« less

High-resolution interferometic microscope for traceable dimensional nanometrology in Brazil

NASA Astrophysics Data System (ADS)

Malinovski, I.; França, R. S.; Lima, M. S.; Bessa, M. S.; Silva, C. R.; Couceiro, I. B.

2016-07-01

The double color interferometric microscope is developed for step height standards nanometrology traceable to meter definition via primary wavelength laser standards. The setup is based on two stabilized lasers to provide traceable measurements of highest possible resolution down to the physical limits of the optical instruments in sub-nanometer to micrometer range of the heights. The wavelength reference is He-Ne 633 nm stabilized laser, the secondary source is Blue-Green 488 nm grating laser diode. Accurate fringe portion is measured by modulated phase-shift technique combined with imaging interferometry and Fourier processing. Self calibrating methods are developed to correct systematic interferometric errors.

Green synthesis and characterization of graphene nanosheets

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

Tavakoli, Farnosh; Salavati-Niasari, Masoud, E-mail: salavati@kashanu.ac.ir; Department of Inorganic Chemistry, Faculty of Chemistry, University of Kashan, Kashan, P. O. Box. 87317-51167, Islamic Republic of Iran

Highlights: • For the first time, we have synthesized graphene nanosheets in the presence of pomegranate juice. • Here pomegranate juice was used not only as reductant but also as capping agent. • FT-IR, XRD, SEM, EDS and TEM were used to characterize the samples. • According to TEM image, graphene nanosheet is individually exfoliated after stirring for 24 h. • As shown in the TEM image, graphene monolayer is obtained. - Abstract: For the first time, we have successfully synthesized graphene nanosheets in the presence of pomegranate juice. In this approach, pomegranate juice was used not only as reductantmore » but also as capping agent to form graphene nanosheets. At first, the improved Hummer method to oxidize graphite for the synthesis of graphene oxide (GO) was applied, and then the as-produced graphene oxide was reduced by pomegranate juice to form graphene nanosheets. Fourier transformed infrared (FT-IR), X-ray powder diffraction (XRD), scanning electron microscopy (SEM), energy dispersive spectrometry (EDS), high resolution transmission electron microscopy (HRTEM), atomic force microscopy (AFM) and raman were used to characterize the samples. The results obtained from the characterization techniques proved high purity of the final products.« less

Probing plasmodesmata function with biochemical inhibitors.

PubMed

White, Rosemary G

2015-01-01

To investigate plasmodesmata (PD) function, a useful technique is to monitor the effect on cell-to-cell transport of applying an inhibitor of a physiological process, protein, or other cell component of interest. Changes in PD transport can then be monitored in one of several ways, most commonly by measuring the cell-to-cell movement of fluorescent tracer dyes or of free fluorescent proteins. Effects on PD structure can be detected in thin sections of embedded tissue observed using an electron microscope, most commonly a Transmission Electron Microscope (TEM). This chapter outlines commonly used inhibitors, methods for treating different tissues, how to detect altered cell-to-cell transport and PD structure, and important caveats.

Transmission electron microscope sample holder with optical features

DOEpatents

Milas, Mirko [Port Jefferson, NY; Zhu, Yimei [Stony Brook, NY; Rameau, Jonathan David [Coram, NY

2012-03-27

A sample holder for holding a sample to be observed for research purposes, particularly in a transmission electron microscope (TEM), generally includes an external alignment part for directing a light beam in a predetermined beam direction, a sample holder body in optical communication with the external alignment part and a sample support member disposed at a distal end of the sample holder body opposite the external alignment part for holding a sample to be analyzed. The sample holder body defines an internal conduit for the light beam and the sample support member includes a light beam positioner for directing the light beam between the sample holder body and the sample held by the sample support member.

Corrosion performance of 7075 alloy under laser heat treatment

NASA Astrophysics Data System (ADS)

Liu, Tong; Su, Ruiming; Qu, Yingdong; Li, Rongde

2018-05-01

Microstructure, exfoliation corrosion (EXCO), intergranular corrosion (IGC) and potentidynamic polarization test of the 7075 aluminum alloy after retrogression and re-aging (RRA) treatment, and laser retrogression and re-aging (LRRA), respectively, were studied by using scanning electron microscope, and transmission electron microscope (TEM). The results show that after pre-aging, laser treatment (650 W, 2 mm s‑1) and re-aging a lot of matrix precipitates of alloy were precipitated again. The semi-continuous grain boundary precipitates and the wider precipitate-free zones (PFZ) improve the corrosion resistance of the alloy. The corrosion properties of the alloy after LRRA (650 W, 2 mm s‑1) treatment are better than that after RRA treatment.

Parallel excitation-emission multiplexed fluorescence lifetime confocal microscopy for live cell imaging.

PubMed

Zhao, Ming; Li, Yu; Peng, Leilei

2014-05-05

We present a novel excitation-emission multiplexed fluorescence lifetime microscopy (FLIM) method that surpasses current FLIM techniques in multiplexing capability. The method employs Fourier multiplexing to simultaneously acquire confocal fluorescence lifetime images of multiple excitation wavelength and emission color combinations at 44,000 pixels/sec. The system is built with low-cost CW laser sources and standard PMTs with versatile spectral configuration, which can be implemented as an add-on to commercial confocal microscopes. The Fourier lifetime confocal method allows fast multiplexed FLIM imaging, which makes it possible to monitor multiple biological processes in live cells. The low cost and compatibility with commercial systems could also make multiplexed FLIM more accessible to biological research community.

Study of the transverse and longitudinal electric field components of surface plasmon polaritons on flat metal film by polarization-resolved Fourier-space microscopy

NASA Astrophysics Data System (ADS)

Liu, C.; Ong, H. C.

2018-01-01

We have employed a polarization-resolved Fourier-space surface plasmon resonance microscope to determine the electric field component ratio of surface plasmon polaritons (SPPs) propagating on a flat gold film. By using a metallic nanoparticle as a probe to capture the radiation damping of the SPP scattered waves, we find the angular far-field distribution is related to the transverse and longitudinal fields of SPPs. The experiment is supported by analytical and numerical calculations. Our results present a simple but useful approach to probe the behaviors of SPPs such as the transverse spin density as well as the energy density.

Neurite outgrowth stimulatory effects of myco synthesized AuNPs from Hericium erinaceus (Bull.: Fr.) Pers. on pheochromocytoma (PC-12) cells

PubMed Central

Raman, Jegadeesh; Lakshmanan, Hariprasath; John, Priscilla A; Zhijian, Chan; Periasamy, Vengadesh; David, Pamela; Naidu, Murali; Sabaratnam, Vikineswary

2015-01-01

Background Hericium erinaceus has been reported to have a wide range of medicinal properties such as stimulation of neurite outgrowth, promotion of functional recovery of axonotmetic peroneal nerve injury, antioxidant, antihypertensive, and antidiabetic properties. In recent years, the green synthesis of gold nanoparticles (AuNPs) has attracted intense interest due to the potential use in biomedical applications. The aim of this study was to investigate the effects of AuNPs from aqueous extract of H. erinaceus on neurite outgrowth of rat pheochromocytoma (PC-12) cells. Methods The formation of AuNPs was characterized by UV–visible spectrum, energy dispersive X-ray (EDX), field-emission scanning electron microscope (FESEM), transmission electron microscopy (TEM), particle size distribution, and Fourier transform-infrared spectroscopy (FTIR). Furthermore, the neurite extension study of synthesized AuNPs was evaluated by in vitro assay. Results The AuNPs exhibited maximum absorbance between 510 and 600 nm in UV–visible spectrum. FESEM and TEM images showed the existence of nanoparticles with sizes of 20–40 nm. FTIR measurements were carried out to identify the possible biomolecules responsible for capping and efficient stabilization of the nanoparticles. The purity and the crystalline properties were confirmed by EDX diffraction analysis, which showed strong signals with energy peaks in the range of 2–2.4 keV, indicating the existence of gold atoms. The synthesized AuNPs showed significant neurite extension on PC-12 cells. Nerve growth factor 50 ng/mL was used as a positive control. Treatment with different concentrations (nanograms) of AuNPs resulted in neuronal differentiation and neuronal elongation. AuNPs induced maximum neurite outgrowth of 13% at 600 ng/mL concentration. Conclusion In this study, the AuNPs synthesis was achieved by a simple, low-cost, and rapid bioreduction approach. AuNPs were shown to have potential neuronal differentiation and stimulated neurite outgrowth. The water-soluble bioconstituents could be responsible for the neuroactivity. This is the first report for the biosynthesis of AuNPs using the hot aqueous extract of H. erinaceus. PMID:26425086

Neurite outgrowth stimulatory effects of myco synthesized AuNPs from Hericium erinaceus (Bull.: Fr.) Pers. on pheochromocytoma (PC-12) cells.

PubMed

Raman, Jegadeesh; Lakshmanan, Hariprasath; John, Priscilla A; Zhijian, Chan; Periasamy, Vengadesh; David, Pamela; Naidu, Murali; Sabaratnam, Vikineswary

2015-01-01

Hericium erinaceus has been reported to have a wide range of medicinal properties such as stimulation of neurite outgrowth, promotion of functional recovery of axonotmetic peroneal nerve injury, antioxidant, antihypertensive, and antidiabetic properties. In recent years, the green synthesis of gold nanoparticles (AuNPs) has attracted intense interest due to the potential use in biomedical applications. The aim of this study was to investigate the effects of AuNPs from aqueous extract of H. erinaceus on neurite outgrowth of rat pheochromocytoma (PC-12) cells. The formation of AuNPs was characterized by UV-visible spectrum, energy dispersive X-ray (EDX), field-emission scanning electron microscope (FESEM), transmission electron microscopy (TEM), particle size distribution, and Fourier transform-infrared spectroscopy (FTIR). Furthermore, the neurite extension study of synthesized AuNPs was evaluated by in vitro assay. The AuNPs exhibited maximum absorbance between 510 and 600 nm in UV-visible spectrum. FESEM and TEM images showed the existence of nanoparticles with sizes of 20-40 nm. FTIR measurements were carried out to identify the possible biomolecules responsible for capping and efficient stabilization of the nanoparticles. The purity and the crystalline properties were confirmed by EDX diffraction analysis, which showed strong signals with energy peaks in the range of 2-2.4 keV, indicating the existence of gold atoms. The synthesized AuNPs showed significant neurite extension on PC-12 cells. Nerve growth factor 50 ng/mL was used as a positive control. Treatment with different concentrations (nanograms) of AuNPs resulted in neuronal differentiation and neuronal elongation. AuNPs induced maximum neurite outgrowth of 13% at 600 ng/mL concentration. In this study, the AuNPs synthesis was achieved by a simple, low-cost, and rapid bioreduction approach. AuNPs were shown to have potential neuronal differentiation and stimulated neurite outgrowth. The water-soluble bioconstituents could be responsible for the neuroactivity. This is the first report for the biosynthesis of AuNPs using the hot aqueous extract of H. erinaceus.

Detection of microscopic particles present as contaminants in latent fingerprints by means of synchrotron radiation-based Fourier transform infra-red micro-imaging.

PubMed

Banas, A; Banas, K; Breese, M B H; Loke, J; Heng Teo, B; Lim, S K

2012-08-07

Synchrotron radiation-based Fourier transform infra-red (SR-FTIR) micro-imaging has been developed as a rapid, direct and non-destructive technique. This method, taking advantage of the high brightness and small effective source size of synchrotron light, is capable of exploring the molecular chemistry within the microstructures of microscopic particles without their destruction at high spatial resolutions. This is in contrast to traditional "wet" chemical methods, which, during processing for analysis, often caused destruction of the original samples. In the present study, we demonstrate the potential of SR-FTIR micro-imaging as an effective way to accurately identify microscopic particles deposited within latent fingerprints. These particles are present from residual amounts of materials left on a person's fingers after handling such materials. Fingerprints contaminated with various types of powders, creams, medications and high explosive materials (3-nitrooxy-2,2-bis(nitrooxymethyl)propyl nitrate (PETN), 1,3,5-trinitro-1,3,5-triazinane (RDX), 2-methyl-1,3,5-trinitrobenzene (TNT)) deposited on various - daily used - substrates have been analysed herein without any further sample preparation. A non-destructive method for the transfer of contaminated fingerprints from hard-to-reach areas of the substrates to the place of analysis is also presented. This method could have a significant impact on forensic science and could dramatically enhance the amount of information that can be obtained from the study of fingerprints.

Synthesis of Cu/CuO nanoparticles in mesoporous material by solid state reaction

NASA Astrophysics Data System (ADS)

Sohrabnezhad, Sh.; Valipour, A.

2013-10-01

The Mobil Composition of Matter No. 41 (MCM-41) containing 1.0 and 5.0 wt.% of Cu was synthesized under solid state reaction. The calcinations of samples were done at two different temperatures, 500 and 300 °C. X-ray diffraction (XRD), UV-Vis diffuse reflectance spectroscopy (UV-Vis DRS), Fourier transform infrared spectroscopy (FTIR) and transmission electron microscopy (TEM) were used for samples characterization. Powder X-ray diffraction showed that when Cu(CH3COO)2 content is about 1.0 wt.% in Cu/MCM-41, the guest CuO-NPs and copper ions is formed on the silica channel wall, and more exists in the crystalline state. When Cu(CH3COO)2 content exceeds this value (5.0 wt.%), CuO nanoparticles and Cu2+ ions can be observed in low crystalline state. From the diffuse reflectance spectra it was confirmed that 5 wt.% Cu/MCM-41 sample calcined at 500 °C show plasmon resonance band due to Cu nanoparticles in the range between 500 and 600 nm and small copper clusters Cun in 450 nm. It also shows that some of the Cu2+ ions are present octahedrally in extraframework position in all samples. Both fourier transform infrared and diffuse reflectance spectra indicate that some of Cu2+ ions are tetrahedrally within the framework position in 1 wt.% Cu/MCM-41 samples. TEM images indicated that nanoparticles size of CuO is in range of 30-40 nm.

Morphological studies of the developing human esophageal epithelium.

PubMed

Ménard, D

1995-06-15

This article focusses on the structural development of human esophageal ciliated epithelium. A combination of transmission electron microscopic (TEM), scanning electron microscopic (SEM), radioautographic, and light microscopic (LM) analyses were carried out using intact fetal tissues between 8 and 20 weeks of gestation as well as cultured esophageal explants. Up to the age of 10 weeks, the stratified esophageal epithelium consisted of two longitudinal primary folds. The surface cells were undifferentiated and contained large glycogen aggregates. Between 11 and 16 weeks, the primary folds (now up to four) had developed secondary folds. The thickness of the epithelium drastically increased (123%) in concomittance with a differentiation of surface columnar ciliated cells. These highly specialized surface cells exhibited junctional complexes and well-developed organelles with numerous microvilli interspersed among the cilia. Transverse sections revealed the internal structure of the cilia with a consistent pattern of nine doublet microtubules surrounding a central pair of single microtubules. Freeze-fracture studies illustrated the presence of a ciliary necklace composed of 6 ring-like rows of intramembranous particles. They also revealed the structure of ciliary cell tight junctions consisting of up to nine anastomosing strands (P-face) or complementary grooves (E-face). Ultrastructural studies (LM, TEM, SEM) of the esophageal squamous epithelium obtained after 15 days of culture showed that the newly formed epithelium was similar to adult human epithelium. Finally LM and SEM observations established that the esophagogastric junction was not yet well delineated, consisting of a transitional area composed of a mixture of esophageal ciliated cells and gastric columnar mucous cells.

What transmission electron microscopes can visualize now and in the future.

PubMed

Müller, Shirley A; Aebi, Ueli; Engel, Andreas

2008-09-01

Our review concentrates on the progress made in high-resolution transmission electron microscopy (TEM) in the past decade. This includes significant improvements in sample preparation by quick-freezing aimed at preserving the specimen in a close-to-native state in the high vacuum of the microscope. Following advances in cold stage and TEM vacuum technology systems, the observation of native, frozen hydrated specimens has become a widely used approach. It fostered the development of computer guided, fully automated low-dose data acquisition systems allowing matched pairs of images and diffraction patterns to be recorded for electron crystallography, and the collection of entire tilt-series for electron tomography. To achieve optimal information transfer to atomic resolution, field emission electron guns combined with acceleration voltages of 200-300 kV are now routinely used. The outcome of these advances is illustrated by the atomic structure of mammalian aquaporin-O and by the pore-forming bacterial cytotoxin ClyA resolved to 12 A. Further, the Yersinia injectisome needle, a bacterial pseudopilus and the binding of phalloidin to muscle actin filaments were chosen to document the advantage of the high contrast offered by dedicated scanning transmission electron microscopy (STEM) and/or the STEM's ability to measure the mass of protein complexes and directly link this to their shape. Continued progress emerging from leading research laboratories and microscope manufacturers will eventually enable us to determine the proteome of a single cell by electron tomography, and to more routinely solve the atomic structure of membrane proteins by electron crystallography.

Influence of perfluorocarbons on Carbamazepine and Benzodiazepine for a neuro-lung protective strategy.

PubMed

Natchimuthu, V; Thomas, Sabu; Ramalingam, Murugan; Ravi, S

2017-09-01

Lennox-Gastaut syndrome (LGS) is commonly characterized by a triad of features including multiple seizure types, intellectual disability or regression. LGS type of seizures is epilepsy which is due to abnormal vibrations occurring in seizures. During the time of such abnormal vibrations, both the seizures and the lungs suffer a lack in oxygen content to a considerable extent. This results in prolonged vibrations and loses of nervous control. As a neuro-lung protective strategy, a novel attempt has been made to enrich both seizures and lungs with oxygen content through the support of Perfluorodecalin (an excellent oxygen carrier) C 10 F 18 (PFD) and Perfluorohexane C 6 F 14 (PFH) along with an enhancement in the antiepileptic activity by the two chosen antiepileptic drugs (AEDs) Carbamazepine (CBZ) and Benzodiazepine (BDZ). Perfluorodecalin C 10 F 18 (PFD) and Perfluorohexane C 6 F 14 (PFH) emulsions were prepared by sonication process with combination of nonionic emulsifier, Lecithin (l-α-phosphatidylcholine) as a surfactant in Aqueous phase medium. These emulsions were mixed with Carbamazepine (CBZ) and Benzodiazepine (BDZ) drugs maintained at a temperature of about -20°C to 20°C and were set to slow evaporation process. The products are subjected to Optical microscope, Transmission electron microscopy (TEM) and Scanning Electron Microscope (SEM) - Energy dispersive X-ray Spectroscopy (EDS). Study reveals the co-existence of fluorine and drug ensuring the oxygen uptake by the drug. Morphology of TEM, Optical microscopic images and the particle diameter estimated through Image_J confirms this analysis. Copyright © 2017 Elsevier Ltd. All rights reserved.

Aspects of CO2 laser engraving of printing cylinders.

PubMed

Atanasov, P A; Maeno, K; Manolov, V P

1999-03-20

Results of the experimental and theoretical investigations of CO(2) laser-engraved cylinders are presented. The processed surfaces of test samples are examined by a phase-stepping laser interferometer, digital microscope, and computer-controlled profilometer. Fourier analysis is made on the patterns parallel to the axis of the laser-scribed test ceramic cylinders. The problem of the visually observed banding is discussed.

Microstructure characterization of Al matrix composite reinforced with Ti-6Al-4V meshes after compression by scanning electron microscope and transmission electron microscope.

PubMed

Guo, Q; Sun, D L; Han, X L; Cheng, S R; Chen, G Q; Jiang, L T; Wu, G H

2012-02-01

Compressive properties of Al matrix composite reinforced with Ti-6Al-4V meshes (TC4(m)/5A06 Al composite) under the strain rates of 10(-3)S(-1) and 1S(-1) at different temperature were measured and microstructure of composites after compression was characterized by scanning electron microscope (SEM) and transmission electron microscope (TEM). Compressive strength decreased with the test temperature increased and the strain-rate sensitivity (R) of composite increased with the increasing temperature. SEM observations showed that grains of Al matrix were elongated severely along 45° direction (angle between axis direction and fracture surface) and TC4 fibres were sheared into several parts in composite compressed under the strain rate of 10(-3)S(-1) at 25°C and 250°C. Besides, amounts of cracks were produced at the interfacial layer between TC4 fibre and Al matrix and in (Fe, Mn)Al(6) phases. With the compressive temperature increasing to 400°C, there was no damage at the interfacial layer between TC4 fibre and Al matrix and in (Fe, Mn)Al(6) phases, while equiaxed recrystal grains with sizes about 10 μm at the original grain boundaries of Al matrix were observed. However, interface separation of TC4 fibres and Al matrix occurred in composite compressed under the strain rate of 1S(-1) at 250°C and 400°C. With the compressive temperature increasing from 25°C to 100°C under the strain rate of 10(-3) S(-1), TEM microstructure in Al matrix exhibited high density dislocations and slipping bands (25°C), polygonized dislocations and dynamic recovery (100°C), equiaxed recrystals with sizes below 500 μm (250°C) and growth of equiaxed recrystals (400°C), respectively. Copyright © 2011 Elsevier Ltd. All rights reserved.

Field modeling and ray-tracing of a miniature scanning electron microscope beam column.

PubMed

Loyd, Jody S; Gregory, Don A; Gaskin, Jessica A

2017-08-01

A miniature scanning electron microscope (SEM) focusing column design is introduced and its potential performance assessed through an estimation of parameters that affect the probe radius, to include source size, spherical and chromatic aberration, diffraction and space charge broadening. The focusing column, a critical component of any SEM capable of operating on the lunar surface, was developed by the NASA Marshall Space Flight Center and Advanced Research Systems. The ray-trace analysis presented uses a model of the electrostatic field (within the focusing column) that is first calculated using the boundary element method (BEM). This method provides flexibility in modeling the complex electrode shapes of practical electron lens systems. A Fourier series solution of the lens field is then derived within a cylindrical domain whose boundary potential is provided by the BEM. Used in this way, the Fourier series solution is an accuracy enhancement to the BEM solution, allowing sufficient precision to assess geometric aberrations through direct ray-tracing. Two modes of operation with distinct lens field solutions are described. © The Author 2017. Published by Oxford University Press on behalf of The Japanese Society of Microscopy. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

Microscopic theory of optical absorption in graphene enhanced by lattices of plasmonic nanoparticles

NASA Astrophysics Data System (ADS)

Mueller, Niclas S.; Reich, Stephanie

2018-06-01

We present a microscopic description of plasmon-enhanced optical absorption in graphene, which is based on perturbation theory. We consider the interaction of graphene with a lattice of plasmonic nanoparticles, as was previously realized experimentally. By using tight-binding wave functions for the electronic states of graphene and the dipole approximation for the plasmon, we obtain analytic expressions for the coupling matrix element and enhanced optical absorption. The plasmonic nanostructure induces nonvertical optical transitions in the band structure of graphene with selection rules for the momentum transfer that depend on the periodicity of the plasmonic lattice. The plasmon-mediated optical absorption leads to an anisotropic carrier population around the K point in phase space, which depends on the polarization pattern of the plasmonic near field in the graphene plane. Using Fourier optics, we draw a connection to a macroscopic approach, which is independent from graphene-specific parameters. Each Fourier component of the plasmonic near field corresponds to the momentum transfer of an optical transition. Both approaches lead to the same expression for the integrated optical absorption enhancement, which is relevant for the photocurrent enhancement in graphene-based optoelectronic devices.

In situ transmission electron microscopic observations of redox cycling of a Ni-ScSZ cermet fuel cell anode.

PubMed

Matsuda, Junko; Kawasaki, Tatsuya; Futamura, Shotaro; Kawabata, Tsutomu; Taniguchi, Shunsuke; Sasaki, Kazunari

2018-05-19

In situ transmission electron microscopy (TEM) observations of a Ni(O)-Sc2O3-stabilized ZrO2 (ScSZ; 10 mol% Sc2O3, 1 mol% CeO2, 89 mol% ZrO2) anode in a solid oxide fuel cell (SOFC) have been performed at high temperatures under a hydrogen/oxygen gas atmosphere using an environmental transmission electron microscope (ETEM); the specimens were removed from cross-sections of the real SOFC by focused ion beam milling and lifting. When heating the NiO-ScSZ anode under a hydrogen atmosphere of 3 mbar in ETEM, nano-pores were formed at the grain boundaries and on the surface of NiO particles at around 400°C due to the volume shrinkage accompanying the reduction of NiO to Ni. Moreover, densification of Ni occurred when increasing the temperature from 600 to 700°C. High-magnification TEM images obtained in the early stages of NiO reduction revealed that the (111) planes of Ni grew almost parallel to the (111) planes of NiO. In the case of heating Ni-ScSZ under an oxygen atmosphere of 3 mbar in ETEM, oxidation of Ni starting from the surface of the particles occurred above 300°C. All Ni particles became polycrystalline NiO after the temperature was increased to 800°C. Volume expansion/contraction by mass transfer to the outside/inside of the Ni particles in the anode during repeated oxidation/reduction seems to result in the agglomeration of Ni catalysts during long-term SOFC operation. We emphasize that our in situ TEM observations will be applied to observe electrochemical reactions in SOFCs under applied electric fields.

Space Plasma Ion Processing of Ilmenite in the Lunar Soil: Insights from In-Situ TEM Ion Irradiation Experiments

NASA Technical Reports Server (NTRS)

Christoffersen, R.; Keller, L. P.

2007-01-01

Space weathering on the moon and asteroids results largely from the alteration of the outer surfaces of regolith grains by the combined effects of solar ion irradiation and other processes that include deposition of impact or sputter-derived vapors. Although no longer considered the sole driver of space weathering, solar ion irradiation remains a key part of the space weathering puzzle, and quantitative data on its effects on regolith minerals are still in short supply. For the lunar regolith, previous transmission electron microscope (TEM) studies performed by ourselves and others have uncovered altered rims on ilmenite (FeTiO3) grains that point to this phase as a unique "witness plate" for unraveling nanoscale space weathering processes. Most notably, the radiation processed portions of these ilmenite rims consistently have a crystalline structure, in contrast to radiation damaged rims on regolith silicates that are characteristically amorphous. While this has tended to support informal designation of ilmenite as a "radiation resistant" regolith mineral, there are to date no experimental data that directly and quantitatively compare ilmenite s response to ion radiation relative to lunar silicates. Such data are needed because the radiation processed rims on ilmenite grains, although crystalline, are microstructurally and chemically complex, and exhibit changes linked to the formation of nanophase Fe metal, a key space weathering process. We report here the first ion radiation processing study of ilmenite performed by in-situ means using the Intermediate Voltage Electron Microscope- Tandem Irradiation facility (IVEM-Tandem) at Argonne National Laboratory. The capability of this facility for performing real time TEM observations of samples concurrent with ion irradiation makes it uniquely suited for studying the dose-dependence of amorphization and other changes in irradiated samples.

Imaging properties and its improvements of scanning/imaging x-ray microscope

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

Takeuchi, Akihisa, E-mail: take@spring8.or.jp; Uesugi, Kentaro; Suzuki, Yoshio

A scanning / imaging X-ray microscope (SIXM) system has been developed at SPring-8. The SIXM consists of a scanning X-ray microscope with a one-dimensional (1D) X-ray focusing device and an imaging (full-field) X-ray microscope with a 1D X-ray objective. The motivation of the SIXM system is to realize a quantitative and highly-sensitive multimodal 3D X-ray tomography by taking advantages of both the scanning X-ray microscope using multi-pixel detector and the imaging X-ray microscope. Data acquisition process of a 2D image is completely different between in the horizontal direction and in the vertical direction; a 1D signal is obtained with themore » linear-scanning while the other dimensional signal is obtained with the imaging optics. Such condition have caused a serious problem on the imaging properties that the imaging quality in the vertical direction has been much worse than that in the horizontal direction. In this paper, two approaches to solve this problem will be presented. One is introducing a Fourier transform method for phase retrieval from one phase derivative image, and the other to develop and employ a 1D diffuser to produce an asymmetrical coherent illumination.« less

An ultrahigh vacuum multipurpose specimen chamber with sample introduction system for in situ transmission electron microscopy investigations

NASA Technical Reports Server (NTRS)

Heinemann, K.; Poppa, H.

1986-01-01

A commercial transmission electron microscope (TEM), with flat-plate upper pole piece configuration of the objective lens, and top-entry specimen introduction was modified by introducing an ultrahigh vacuum (UHV) specimen chamber for in situ TEM experimentation. The pumping and design principles and special features of this UHV chamber, which makes it possible to obtain 5 x 10 to the -10th mbar pressure at the site of the specimen, while maintaining the airlock system that allows operation in the 10 to the -10th mbar range within 15 min after specimen change, are described. Design operating pressures and image quality (resolution of metal particles smaller than 1 nm in size) were achieved. Schematic drawings and design dimensions are included.

A FIB/TEM Study of a Complex Wark-Lovering Rim on a Vigarano CAI

NASA Technical Reports Server (NTRS)

Keller, L. P.; Needham, A. W.; Messenger, S.

2013-01-01

Wark-Lovering (WL) rims are thin multilayered mineral sequences that surround most Ca, Al-rich inclusions (CAIs). Several processes have been proposed for WL rim formation, including condensation, flash-heating or reaction with a nebular reservoir, or combinations of these [e.g. 1-7], but no consensus exists. Our previous coordinated transmission electron microscope (TEM) and NanoSIMS O isotopic measurements showed that a WL rim experienced flash heating events in a nebular environment with planetary O isotopic composition, distinct from the (16)O-rich formation environment [6]. Our efforts have focused on CAIs from the CV(sub red) chondrites, especially Vigarano, because these have escaped much of the parent body alteration effects that are common in CAIs from CV(sub ox) group.

Grain Nucleation and Growth in Deformed NiTi Shape Memory Alloys: An In Situ TEM Study

NASA Astrophysics Data System (ADS)

Burow, J.; Frenzel, J.; Somsen, C.; Prokofiev, E.; Valiev, R.; Eggeler, G.

2017-12-01

The present study investigates the evolution of nanocrystalline (NC) and ultrafine-grained (UFG) microstructures in plastically deformed NiTi. Two deformed NiTi alloys were subjected to in situ annealing in a transmission electron microscope (TEM) at 400 and 550 °C: an amorphous material state produced by high-pressure torsion (HPT) and a mostly martensitic partly amorphous alloy produced by wire drawing. In situ annealing experiments were performed to characterize the microstructural evolution from the initial nonequilibrium states toward energetically more favorable microstructures. In general, the formation and evolution of nanocrystalline microstructures are governed by the nucleation of new grains and their subsequent growth. Austenite nuclei which form in HPT and wire-drawn microstructures have sizes close to 10 nm. Grain coarsening occurs in a sporadic, nonuniform manner and depends on the physical and chemical features of the local environment. The mobility of grain boundaries in NiTi is governed by the local interaction of each grain with its microstructural environment. Nanograin growth in thin TEM foils seems to follow similar kinetic laws to those in bulk microstructures. The present study demonstrates the strength of in situ TEM analysis and also highlights aspects which need to be considered when interpreting the results.

A method for measuring the local gas pressure within a gas-flow stage in situ in the transmission electron microscope

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

Colby, Robert J.; Alsem, Daan H.; Liyu, Andrey V.

2015-06-01

The development of environmental transmission electron microscopy (TEM) has enabled in situ experiments in a gaseous environment with high resolution imaging and spectroscopy. Addressing scientific challenges in areas such as catalysis, corrosion, and geochemistry can require pressures much higher than the ~20 mbar achievable with a differentially pumped, dedicated environmental TEM. Gas flow stages, in which the environment is contained between two semi-transparent thin membrane windows, have been demonstrated at pressures of several atmospheres. While this constitutes significant progress towards operando measurements, the design of many current gas flow stages is such that the pressure at the sample cannot necessarilymore » be directly inferred from the pressure differential across the system. Small differences in the setup and design of the gas flow stage can lead to very different sample pressures. We demonstrate a method for measuring the gas pressure directly, using a combination of electron energy loss spectroscopy and TEM imaging. This method requires only two energy filtered TEM images, limiting the measurement time to a few seconds and can be performed during an ongoing experiment at the region of interest. This approach provides a means to ensure reproducibility between different experiments, and even between very differently designed gas flow stages.« less

The influence of hair bleach on the ultrastructure of human hair with special reference to hair damage.

PubMed

Imai, Takehito

2011-05-01

The influence of human hair bleaching agents with different bleaching strength on the ultrastructure of human hair was studied using a transmission electron microscope (TEM) and an energy dispersive X-ray spectrometer equipped with TEM (EDS-TEM). Two kinds of bleaching agents were used: a lightener agent with a weak bleaching effect and a powder-bleach with a stronger bleaching effect. From the comparison of the bleaching properties obtained by the electronic staining of black and white hair samples, it was suggested that the permeability of hair was increased by bleaching, and there was an increase of the stainability of hair subjected to electronic staining. The bleaching action provoked the decomposition of melanin granules and the flow out of granular contents into the intermacrofibrillar matrix. Some metal elements were detected in the melanin granular matrix by EDS-TEM. As a result, the diffusion of metal elements into the intermacrofibrillar matrix promoted further damage to the hair by catalytic action with the hydrogen peroxide in the bleaching agents outside the melanin granules. Further study will lead us to the edge of the development of a new bleaching agent, which reacts only with melanin granules and causes the minimum of damage to outside the melanin granules.

Antibacterial properties of silver nanoparticles synthesized by marine Ochrobactrum sp.

PubMed

Thomas, Roshmi; Janardhanan, Anju; Varghese, Rintu T; Soniya, E V; Mathew, Jyothis; Radhakrishnan, E K

2014-01-01

Metal nanoparticle synthesis is an interesting area in nanotechnology due to their remarkable optical, magnetic, electrical, catalytic and biomedical properties, but there needs to develop clean, non-toxic and environmental friendly methods for the synthesis and assembly of nanoparticles. Biological agents in the form of microbes have emerged up as efficient candidates for nanoparticle synthesis due to their extreme versatility to synthesize diverse nanoparticles with varying size and shape. In the present study, an eco favorable method for the biosynthesis of silver nanoparticles using marine bacterial isolate has been attempted. Very interestingly, molecular identification proved it as a strain of Ochrobactrum anhtropi. In addition, the isolate was found to have the potential to form silver nanoparticles intracellularly at room temperature within 24 h. The biosynthesized silver nanoparticles were characterized by UV-Vis spectroscopy, transmission electron microscope (TEM) and scanning electron microscope (SEM). The UV-visible spectrum of the aqueous medium containing silver nanoparticles showed a peak at 450 nm corresponding to the plasmon absorbance of silver nanoparticles. The SEM and TEM micrographs revealed that the synthesized silver nanoparticles were spherical in shape with a size range from 38 nm - 85 nm. The silver nanoparticles synthesized by the isolate were also used to explore its antibacterial potential against pathogens like Salmonella Typhi, Salmonella Paratyphi, Vibrio cholerae and Staphylococcus aureus.

Antibacterial properties of silver nanoparticles synthesized by marine Ochrobactrum sp

PubMed Central

Thomas, Roshmi; Janardhanan, Anju; Varghese, Rintu T.; Soniya, E.V.; Mathew, Jyothis; Radhakrishnan, E.K.

2014-01-01

Metal nanoparticle synthesis is an interesting area in nanotechnology due to their remarkable optical, magnetic, electrical, catalytic and biomedical properties, but there needs to develop clean, non-toxic and environmental friendly methods for the synthesis and assembly of nanoparticles. Biological agents in the form of microbes have emerged up as efficient candidates for nanoparticle synthesis due to their extreme versatility to synthesize diverse nanoparticles with varying size and shape. In the present study, an eco favorable method for the biosynthesis of silver nanoparticles using marine bacterial isolate has been attempted. Very interestingly, molecular identification proved it as a strain of Ochrobactrum anhtropi. In addition, the isolate was found to have the potential to form silver nanoparticles intracellularly at room temperature within 24 h. The biosynthesized silver nanoparticles were characterized by UV-Vis spectroscopy, transmission electron microscope (TEM) and scanning electron microscope (SEM). The UV-visible spectrum of the aqueous medium containing silver nanoparticles showed a peak at 450 nm corresponding to the plasmon absorbance of silver nanoparticles. The SEM and TEM micrographs revealed that the synthesized silver nanoparticles were spherical in shape with a size range from 38 nm – 85 nm. The silver nanoparticles synthesized by the isolate were also used to explore its antibacterial potential against pathogens like Salmonella Typhi, Salmonella Paratyphi, Vibrio cholerae and Staphylococcus aureus. PMID:25763025

Newly recognized hosts for uranium in the Hanford Site vadose zone

USGS Publications Warehouse

Stubbs, J.E.; Veblen, L.A.; Elbert, D.C.; Zachara, J.M.; Davis, J.A.; Veblen, D.R.

2009-01-01

Uranium contaminated sediments from the U.S. Department of Energy's Hanford Site have been investigated using electron microscopy. Six classes of solid hosts for uranium were identified. Preliminary sediment characterization was carried out using optical petrography, and electron microprobe analysis (EMPA) was used to locate materials that host uranium. All of the hosts are fine-grained and intergrown with other materials at spatial scales smaller than the analytical volume of the electron microprobe. A focused ion beam (FIB) was used to prepare electron-transparent specimens of each host for the transmission electron microscope (TEM). The hosts were identified as: (1) metatorbernite [Cu(UO2)2(PO4)2??8H2O]; (2) coatings on sediment clasts comprised mainly of phyllosilicates; (3) an amorphous zirconium (oxyhydr)oxide found in clast coatings; (4) amorphous and poorly crystalline materials that line voids within basalt lithic fragments; (5) amorphous palagonite surrounding fragments of basaltic glass; and (6) Fe- and Mn-oxides. These findings demonstrate the effectiveness of combining EMPA, FIB, and TEM to identify solid-phase contaminant hosts. Furthermore, they highlight the complexity of U geochemistry in the Hanford vadose zone, and illustrate the importance of microscopic transport in controlling the fate of contaminant metals in the environment. ?? 2008 Elsevier Ltd.

On the threshold conditions for electron beam damage of asbestos amosite fibers in the transmission electron microscope (TEM).

PubMed

Martin, Joannie; Beauparlant, Martin; Sauvé, Sébastien; L'Espérance, Gilles

2016-12-01

Asbestos amosite fibers were investigated to evaluate the damage caused by a transmission electron microscope (TEM) electron beam. Since elemental x-ray intensity ratios obtained by energy dispersive x-ray spectroscopy (EDS) are commonly used for asbestos identification, the impact of beam damage on these ratios was evaluated. It was determined that the magnesium/silicon ratio best represented the damage caused to the fiber. Various tests showed that most fibers have a current density threshold above which the chemical composition of the fiber is modified. The value of this threshold current density varied depending on the fiber, regardless of fiber diameter, and in some cases could not be determined. The existence of a threshold electron dose was also demonstrated. This value was dependent on the current density used and can be increased by providing a recovery period between exposures to the electron beam. This study also established that the electron beam current is directly related to the damage rate above a current density of 165 A/cm 2 . The large number of different results obtained suggest, that in order to ensure that the amosite fibers are not damaged, analysis should be conducted below a current density of 100 A/cm 2 .

Meretrix lusoria--a natural biocomposite material: in situ analysis of hierarchical fabrication and micro-hardness.

PubMed

Zhu, Zhihong; Tong, Hua; Ren, Yaoyao; Hu, Jiming

2006-01-01

The ultrastructure of clam (Meretrix lusoria) was investigated by means of scanning electron microscope (SEM), transmission electron microscope (TEM) and X-ray diffraction analyzer (XRD) combining with in situ texture decalcified technique and the micro-hardness of clam was determined, in order to understand the spatial relationship between the mineral phase and organic matrix and further explain the correlation between the property and structure. The results showed that hierarchical fabrication is the major structure character of this mollusc shell. There is specific braided structure forming from domains composed of needle-like structure made up of the single crystal of aragonite. High magnification TEM image of clam indicates the intracrystal region of the aragonite single crystal is made up of subgrain phase and some amorphous substance. There are various crystal grain growth preferential orientations in the different growth direction of the shell. An amount of organic microtubule distribute evenly in the base of calcium carbonate as reinforcement phase. The mechanical property of this natural biological composite is better than other aragonite layer of mollusc shells and pearls according to the data of micro-hardness testing. The braided structure and organic microtubule reinforcement phase are responsible for its high mechanical performance. The stereo hierarchical fabrication of clam was elucidated for the first time.

Probing the Behaviors of Gold Nanorods in Metastatic Breast Cancer Cells Based on UV-vis-NIR Absorption Spectroscopy

PubMed Central

Zhang, Weiqi; Ji, Yinglu; Meng, Jie; Wu, Xiaochun; Xu, Haiyan

2012-01-01

In this work, behaviors of positively-charged AuNRs in a highly metastatic tumor cell line MDA-MB-231 are examined based on UV-vis-NIR absorption spectroscopy in combination with inductively coupled plasma mass spectrometry (ICP-MS), transmission electron microscopy (TEM) and dark-field microscopic observation. It is found that characteristic surface plasmon resonance (SPR) peaks of AuNRs can be detected using spectroscopic method within living cells that have taken up AuNRs. The peak area of transverse SPR band is shown to be proportionally related to the amount of AuNRs in the cells determined with ICP-MS, which suggests a facile and real time quantification method for AuNRs in living cells. The shape of longitudinal SPR band in UV-vis-NIR spectrum reflects the aggregation state of AuNRs in the cells during the incubation period, which is proved by TEM and microscopic observations. Experimental results reveal that AuNRs are internalized by the cells rapidly; the accumulation, distribution and aggregation of AuNRs in the cells compartments are time and dose dependent. The established spectroscopic analysis method can not only monitor the behaviors of AuNRs in living cells but may also be helpful in choosing the optimum laser stimulation wavelength for anti-tumor thermotherapy. PMID:22384113

Cellular distribution of uranium after acute exposure of renal epithelial cells: SEM, TEM and nuclear microscopy analysis

NASA Astrophysics Data System (ADS)

Carrière, Marie; Gouget, Barbara; Gallien, Jean-Paul; Avoscan, Laure; Gobin, Renée; Verbavatz, Jean-Marc; Khodja, Hicham

2005-04-01

The major health effect of uranium exposure has been reported to be chemical kidney toxicity, functional and histological damages being mainly observed in proximal tubule cells. Uranium enters the proximal tubule as uranyl-bicarbonate or uranyl-citrate complexes. The aim of our research is to investigate the mechanisms of uranium toxicity, intracellular accumulation and repartition after acute intoxication of rat renal proximal tubule epithelial cells, as a function of its chemical form. Microscopic observations of renal epithelial cells after acute exposure to uranyl-bicarbonate showing the presence of intracellular precipitates as thin needles of uranyl-phosphate localized in cell lysosomes have been published. However the initial site of precipitates formation has not been identified yet: they could either be formed outside the cells before internalization, or directly inside the cells. Uranium solubility as a function and initial concentration was specified by ICP-MS analysis of culture media. In parallel, uranium uptake and distribution in cell monolayers exposed to U-bicarbonate was investigated by nuclear microprobe analyses. Finally, the presence of uranium precipitates was tested out by scanning electron microscopic observations (SEM), while extracellular and/or intracellular precipitates were observed on thin sections of cells by transmission electron microscopy (TEM).

The influence of structure depth on image blurring of micrometres-thick specimens in MeV transmission electron imaging.

PubMed

Wang, Fang; Sun, Ying; Cao, Meng; Nishi, Ryuji

2016-04-01

This study investigates the influence of structure depth on image blurring of micrometres-thick films by experiment and simulation with a conventional transmission electron microscope (TEM). First, ultra-high-voltage electron microscope (ultra-HVEM) images of nanometer gold particles embedded in thick epoxy-resin films were acquired in the experiment and compared with simulated images. Then, variations of image blurring of gold particles at different depths were evaluated by calculating the particle diameter. The results showed that with a decrease in depth, image blurring increased. This depth-related property was more apparent for thicker specimens. Fortunately, larger particle depth involves less image blurring, even for a 10-μm-thick epoxy-resin film. The quality dependence on depth of a 3D reconstruction of particle structures in thick specimens was revealed by electron tomography. The evolution of image blurring with structure depth is determined mainly by multiple elastic scattering effects. Thick specimens of heavier materials produced more blurring due to a larger lateral spread of electrons after scattering from the structure. Nevertheless, increasing electron energy to 2MeV can reduce blurring and produce an acceptable image quality for thick specimens in the TEM. Copyright © 2016 Elsevier Ltd. All rights reserved.

Differences between time domain and Fourier domain optical coherence tomography in imaging tissues.

PubMed

Gao, W; Wu, X

2017-11-01

It has been numerously demonstrated that both time domain and Fourier domain optical coherence tomography (OCT) can generate high-resolution depth-resolved images of living tissues and cells. In this work, we compare the common points and differences between two methods when the continuous and random properties of live tissue are taken into account. It is found that when relationships that exist between the scattered light and tissue structures are taken into account, spectral interference measurements in Fourier domain OCT (FDOCT) is more advantageous than interference fringe envelope measurements in time domain OCT (TDOCT) in the cases where continuous property of tissue is taken into account. It is also demonstrated that when random property of tissue is taken into account FDOCT measures the Fourier transform of the spatial correlation function of the refractive index and speckle phenomena will limit the effective limiting imaging resolution in both TDOCT and FDOCT. Finally, the effective limiting resolution of both TDOCT and FDOCT are given which can be used to estimate the effective limiting resolution in various practical applications. © 2017 The Authors Journal of Microscopy © 2017 Royal Microscopical Society.

Chemical phase analysis of seed mediated synthesized anisotropic silver nanoparticles

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

Bharti, Amardeep, E-mail: abharti@pu.ac.in; Goyal, Navdeep; Singh, Suman

Noble-metal nanoparticles are of great interest because of its broad applications almost in every stream (i.e. biology, chemistry and engineering) due to their unique size/shape dependant properties. In this paper, chemical phase of seed mediated synthesized anisotropic silver nanoparticle (AgNPs) has been investigated via fourier transform infrared spectroscopy (FTIR) and thermogravimetric analysis (TGA). These nanaoparticles were synthesized by seed-growth method controlled by urea and dextrose results to highly stable 12-20 nm particle size revealed by zeta potential and transmission electron microscopy (TEM)

Structural characterization and gas reactions of small metal particles by high resolution in-situ TEM (Transmission Electron Microscopy) and TED (Transmission Electron Diffraction)

NASA Technical Reports Server (NTRS)

Heinemann, K.

1987-01-01

The detection and size analysis of small metal particles supported on amorphous substrates becomes increasingly difficult when the particle size approaches that of the phase contrast background structures of the support. An approach of digital image analysis, involving Fourier transformation of the original image, filtering, and image reconstruction was studied with respect to the likelihood of unambiguously detecting particles of less than 1 nm diameter on amorphous substrates from a single electron micrograph.

Near-common-path interferometer for imaging Fourier-transform spectroscopy in wide-field microscopy

PubMed Central

Wadduwage, Dushan N.; Singh, Vijay Raj; Choi, Heejin; Yaqoob, Zahid; Heemskerk, Hans; Matsudaira, Paul; So, Peter T. C.

2017-01-01

Imaging Fourier-transform spectroscopy (IFTS) is a powerful method for biological hyperspectral analysis based on various imaging modalities, such as fluorescence or Raman. Since the measurements are taken in the Fourier space of the spectrum, it can also take advantage of compressed sensing strategies. IFTS has been readily implemented in high-throughput, high-content microscope systems based on wide-field imaging modalities. However, there are limitations in existing wide-field IFTS designs. Non-common-path approaches are less phase-stable. Alternatively, designs based on the common-path Sagnac interferometer are stable, but incompatible with high-throughput imaging. They require exhaustive sequential scanning over large interferometric path delays, making compressive strategic data acquisition impossible. In this paper, we present a novel phase-stable, near-common-path interferometer enabling high-throughput hyperspectral imaging based on strategic data acquisition. Our results suggest that this approach can improve throughput over those of many other wide-field spectral techniques by more than an order of magnitude without compromising phase stability. PMID:29392168

Autofocus algorithm using one-dimensional Fourier transform and Pearson correlation

NASA Astrophysics Data System (ADS)

Bueno Mario, A.; Alvarez-Borrego, Josue; Acho, L.

2004-10-01

A new autofocus algorithm based on one-dimensional Fourier transform and Pearson correlation for Z automatized microscope is proposed. Our goal is to determine in fast response time and accuracy, the best focused plane through an algorithm. We capture in bright and dark field several images set at different Z distances from biological organism sample. The algorithm uses the one-dimensional Fourier transform to obtain the image frequency content of a vectors pattern previously defined comparing the Pearson correlation of these frequency vectors versus the reference image frequency vector, the most out of focus image, we find the best focusing. Experimental results showed the algorithm has fast response time and accuracy in getting the best focus plane from captured images. In conclusions, the algorithm can be implemented in real time systems due fast response time, accuracy and robustness. The algorithm can be used to get focused images in bright and dark field and it can be extended to include fusion techniques to construct multifocus final images beyond of this paper.

[Authentication of Trace Material Evidence in Forensic Science Field with Infrared Microscopic Technique].

PubMed

Jiang, Zhi-quan; Hu, Ke-liang

2016-03-01

In the field of forensic science, conventional infrared spectral analysis technique is usually unable to meet the detection requirements, because only very a few trace material evidence with diverse shapes and complex compositions, can be extracted from the crime scene. Infrared microscopic technique is developed based on a combination of Fourier-transform infrared spectroscopic technique and microscopic technique. Infrared microscopic technique has a lot of advantages over conventional infrared spectroscopic technique, such as high detection sensitivity, micro-area analysisand nondestructive examination. It has effectively solved the problem of authentication of trace material evidence in the field of forensic science. Additionally, almost no external interference is introduced during measurements by infrared microscopic technique. It can satisfy the special need that the trace material evidence must be reserved for witness in court. It is illustrated in detail through real case analysis in this experimental center that, infrared microscopic technique has advantages in authentication of trace material evidence in forensic science field. In this paper, the vibration features in infrared spectra of material evidences, including paints, plastics, rubbers, fibers, drugs and toxicants, can be comparatively analyzed by means of infrared microscopic technique, in an attempt to provide powerful spectroscopic evidence for qualitative diagnosis of various criminal and traffic accident cases. The experimental results clearly suggest that infrared microscopic technique has an incomparable advantage and it has become an effective method for authentication of trace material evidence in the field of forensic science.

Effect of reduced graphene oxide-carbon nanotubes hybrid nanofillers in mechanical properties of polymer nanocomposites

NASA Astrophysics Data System (ADS)

Sa, Kadambinee; Mahakul, Prakash C.; Subramanyam, B. V. R. S.; Raiguru, Jagatpati; Das, Sonali; Alam, Injamul; Mahanandia, Pitamber

2018-03-01

Graphene and carbon nanotubes (CNTs) have tremendous interest as reinforcing fillers due to their excellent physical properties. However, their reinforcing effect in polymer matrix is limited due to agglomeration of graphene and CNTs within the polymer matrix. Mechanical properties by the admixture of reduced graphene oxide (rGO) and CNTs in Poly (methyl methacrylate) (PMMA) prepared by solution mixing method has been investigated. The prepared samples are characterized using X-ray diffraction (XRD), scanning electron microscope (SEM), transmission electron microscope (TEM) and Raman spectroscopy. The hybrid composite shows improvement in the mechanical properties compared to rGO/PMMA and MWCNTs/PMMA composites due to better interaction between rGO-MWCNTs and polymer matrix.

Parallel excitation-emission multiplexed fluorescence lifetime confocal microscopy for live cell imaging

PubMed Central

Zhao, Ming; Li, Yu; Peng, Leilei

2014-01-01

We present a novel excitation-emission multiplexed fluorescence lifetime microscopy (FLIM) method that surpasses current FLIM techniques in multiplexing capability. The method employs Fourier multiplexing to simultaneously acquire confocal fluorescence lifetime images of multiple excitation wavelength and emission color combinations at 44,000 pixels/sec. The system is built with low-cost CW laser sources and standard PMTs with versatile spectral configuration, which can be implemented as an add-on to commercial confocal microscopes. The Fourier lifetime confocal method allows fast multiplexed FLIM imaging, which makes it possible to monitor multiple biological processes in live cells. The low cost and compatibility with commercial systems could also make multiplexed FLIM more accessible to biological research community. PMID:24921725

FT3D: three-dimensional Fourier analysis on small Unix workstations for electron microscopy and tomographic studies.

PubMed

Lanzavecchia, S; Bellon, P L; Tosoni, L

1993-12-01

FT3D is a self-contained package of tools for three-dimensional Fourier analysis, written in the C language for Unix workstations. It can evaluate direct transforms of three-dimensional real functions, inverse transforms, auto- and cross-correlations and spectra. The library has been developed to support three-dimensional reconstructions of biological structures from projections obtained in the electron microscope. This paper discusses some features of the library, which has been implemented in such a way as to profit from the resources of modern workstations. A table of elapsed times for jobs of different dimensions with different RAM buffers is reported for the particular hardware used in the authors' laboratory.

Transmission Electron Microscopy of Vacuum Sensitive, Radiation Sensitive, and Structurally Delicate Materials

NASA Astrophysics Data System (ADS)

Levin, Barnaby

The transmission electron microscope (TEM) is a powerful tool for characterizing the nanoscale and atomic structure of materials, offering insights into their fundamental physical properties. However, TEM characterization requires very thin samples of material to be placed in a high vacuum environment, and exposed to electron radiation. The high vacuum will induce some materials to evaporate or sublimate, preventing them from being accurately characterized, radiation may damage the sample, causing mass loss, or altering its structure, and structurally delicate samples may collapse and break apart when they are thinned for TEM imaging. This dissertation discusses three different projects in which each of these three difficulties pose challenges to TEM characterization of samples. Firstly, we outline strategies for minimizing radiation damage when characterizing materials in TEM at atomic resolution. We consider types of radiation damage, such as vacancy enhanced displacement, that are not included in some previous discussions of beam damage, and we consider how to minimize damage when using new imaging techniques such as annular bright-field scanning TEM. Our methodology emphasizes the general principle that variation of both signal strength and damage cross section must be considered when choosing an experimental electron beam voltage to minimize damage. Secondly, we consider samples containing sulfur, which is prone to sublimation in high vacuum. TEM is routinely used to attempt to characterize the sulfur distribution in lithium-sulfur battery electrodes, but sublimation artifacts can give misleading results. We demonstrate that sulfur sublimation can be suppressed by using cryogenic TEM to characterize sulfur at very low temperatures, or by using the recently developed airSEM to characterize sulfur without exposing it to vacuum. Finally, we discuss the characterization of aging cadmium yellow paint from early 20th century art masterpieces. The binding medium holding paint particles together bends and curls as sample thickness is reduced to 100 nm, making high resolution characterization challenging. We acquire lattice resolution images of the pigment particles through the binder using high voltage zero-loss energy filtered TEM, allowing us to measure the pigment particle size and determine the pigment crystal structure, providing insight into why the paint is aging and how it was synthesized.

Chromatic Aberration Correction for Atomic Resolution TEM Imaging from 20 to 80 kV.

PubMed

Linck, Martin; Hartel, Peter; Uhlemann, Stephan; Kahl, Frank; Müller, Heiko; Zach, Joachim; Haider, Max; Niestadt, Marcel; Bischoff, Maarten; Biskupek, Johannes; Lee, Zhongbo; Lehnert, Tibor; Börrnert, Felix; Rose, Harald; Kaiser, Ute

2016-08-12

Atomic resolution in transmission electron microscopy of thin and light-atom materials requires a rigorous reduction of the beam energy to reduce knockon damage. However, at the same time, the chromatic aberration deteriorates the resolution of the TEM image dramatically. Within the framework of the SALVE project, we introduce a newly developed C_{c}/C_{s} corrector that is capable of correcting both the chromatic and the spherical aberration in the range of accelerating voltages from 20 to 80 kV. The corrector allows correcting axial aberrations up to fifth order as well as the dominating off-axial aberrations. Over the entire voltage range, optimum phase-contrast imaging conditions for weak signals from light atoms can be adjusted for an optical aperture of at least 55 mrad. The information transfer within this aperture is no longer limited by chromatic aberrations. We demonstrate the performance of the microscope using the examples of 30 kV phase-contrast TEM images of graphene and molybdenum disulfide, showing unprecedented contrast and resolution that matches image calculations.

Micromechanical and in situ shear testing of Al–SiC nanolaminate composites in a transmission electron microscope (TEM)

DOE PAGES

Mayer, Carl; Li, Nan; Mara, Nathan Allan; ...

2014-11-07

Nanolaminate composites show promise as high strength and toughness materials. Still, due to the limited volume of these materials, micron scale mechanical testing methods must be used to determine the properties of these films. To this end, a novel approach combining a double notch shear testing geometry and compression with a flat punch in a nanoindenter was developed to determine the mechanical properties of these films under shear loading. To further elucidate the failure mechanisms under shear loading, in situ TEM experiments were performed using a double notch geometry cut into the TEM foil. Aluminum layer thicknesses of 50nm andmore » 100nm were used to show the effect of constraint on the deformation. Higher shear strength was observed in the 50 nm sample (690±54 MPa) compared to the 100 nm sample (423±28.7 MPa). Additionally, failure occurred along the Al-SiC interface in the 50 nm sample as opposed to failure within the Al layer in the 100 nm sample.« less

LDRD Final Report - In Operando Liquid Cell TEM Characterization of Nickel-Based Electrocatalyst

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

Nielsen, M. H.

2016-11-07

A commercial electrochemistry stage for transmission electron microscopy (TEM) was tested to determine whether to purchase one for the microscopes at Lawrence Livermore National Lab (LLNL). Deposition of a nickel-based electrocatalyst was pursued as a material system for the purpose of testing the stage. The stage was found to be problematic with recurring issues in the electrical connections and vacuum sealing, which has thus far precluded a systematic investigation of the original material system. However, the electrochemical cells purchased through this FS will allow the Lawrence Fellow (Nielsen) to continue testing the stage. Furthermore, discussions with a second vendor, whichmore » released a similar electrochemical TEM stage during the course of this FS, have resulted in an upcoming longterm loan of their stage at Lawrence Berkeley National Lab (LBNL) for testing. In addition, low-loss electron energy-loss spectroscopy (EELS) measurements on nickel-bearing electrolyte solutions led to a broader EELS investigation of solvents and salt solutions. These measurements form the basis of a manuscript in preparation on EELS measurements of the liquid phase.« less

In-situ TEM investigations of graphic-epitaxy and small particles

NASA Technical Reports Server (NTRS)

Heinemann, K.

1983-01-01

Palladium was deposited inside a controlled-vacuum specimen chamber of a transmission electron microscope (TEM) onto MgO and alpha-alumina substrate surfaces. Annealing and various effects of gas exposure of the particulate Pd deposits were studied in-situ by high resolution TEM and electron diffraction. Whereas substrate temperatures of 500 C or annealing of room temperature (RT) deposits to 500 C were needed to obtain epitaxy on sapphire, RT deposits on MgO were perfectly epitaxial. For Pd/MgO a lattice expansion of 2 to 4% was noted; the highest values of expansion were found for the smallest particles. The lattice expansion of small Pd particles on alumina substrates was less than 1%. Long-time RT exposure of Pd/MgO in a vacuum yielded some moblity and coalescence events, but notably fewer than for Pd on sapphire. Exposure to air or oxygen greatly enhanced the particle mobility and coalescence and also resulted in the flattening of Pd particles on MgO substrates. Electron-beam irradiation further enhanced this effect. Exposure to air for several tens of hours of Pd/MgO led to strong coalescence.

Transmission Electron Microscopy of Minerals and Rocks

NASA Astrophysics Data System (ADS)

McLaren, Alex C.

1991-04-01

Of the many techniques that have been applied to the study of crystal defects, none has contributed more to our understanding of their nature and influence on the physical and chemical properties of crystalline materials than transmission electron microscopy (TEM). TEM is now used extensively by an increasing number of earth scientists for direct observation of defect microstructures in minerals and rocks. Transmission Electron Microscopy of Rocks and Minerals is an introduction to the principles of the technique and is the only book to date on the subject written specifically for geologists and mineralogists. The first part of the book deals with the essential physics of the transmission electron microscope and presents the basic theoretical background required for the interpretation of images and electron diffraction patterns. The final chapters are concerned with specific applications of TEM in mineralogy and deal with such topics as planar defects, intergrowths, radiation-induced defects, dislocations and deformation-induced microstructures. The examples cover a wide range of rock-forming minerals from crustal rocks to those in the lower mantle, and also take into account the role of defects in important mineralogical and geological processes.

Microstructure and composition analysis of low-Z/low-Z multilayers by combining hard and resonant soft X-ray reflectivity

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

Rao, P. N., E-mail: pnrao@rrcat.gov.in; Rai, S. K.; Srivastava, A. K.

2016-06-28

Microstructure and composition analysis of periodic multilayer structure consisting of a low electron density contrast (EDC) material combination by grazing incidence hard X-ray reflectivity (GIXR), resonant soft X-ray reflectivity (RSXR), and transmission electron microscopy (TEM) are presented. Measurements of reflectivity at different energies allow combining the sensitivity of GIXR data to microstructural parameters like layer thicknesses and interfacing roughness, with the layer composition sensitivity of RSXR. These aspects are shown with an example of 10-period C/B{sub 4}C multilayer. TEM observation reveals that interfaces C on B{sub 4}C and B{sub 4}C on C are symmetric. Although GIXR provides limited structural informationmore » when EDC between layers is low, measurements using a scattering technique like GIXR with a microscopic technique like TEM improve the microstructural information of low EDC combination. The optical constants of buried layers have been derived by RSXR. The derived optical constants from the measured RSXR data suggested the presence of excess carbon into the boron carbide layer.« less

An Integrated Micro- and Macroarchitectural Analysis of the Drosophila Brain by Computer-Assisted Serial Section Electron Microscopy

PubMed Central

Cardona, Albert; Saalfeld, Stephan; Preibisch, Stephan; Schmid, Benjamin; Cheng, Anchi; Pulokas, Jim; Tomancak, Pavel; Hartenstein, Volker

2010-01-01

The analysis of microcircuitry (the connectivity at the level of individual neuronal processes and synapses), which is indispensable for our understanding of brain function, is based on serial transmission electron microscopy (TEM) or one of its modern variants. Due to technical limitations, most previous studies that used serial TEM recorded relatively small stacks of individual neurons. As a result, our knowledge of microcircuitry in any nervous system is very limited. We applied the software package TrakEM2 to reconstruct neuronal microcircuitry from TEM sections of a small brain, the early larval brain of Drosophila melanogaster. TrakEM2 enables us to embed the analysis of the TEM image volumes at the microcircuit level into a light microscopically derived neuro-anatomical framework, by registering confocal stacks containing sparsely labeled neural structures with the TEM image volume. We imaged two sets of serial TEM sections of the Drosophila first instar larval brain neuropile and one ventral nerve cord segment, and here report our first results pertaining to Drosophila brain microcircuitry. Terminal neurites fall into a small number of generic classes termed globular, varicose, axiform, and dendritiform. Globular and varicose neurites have large diameter segments that carry almost exclusively presynaptic sites. Dendritiform neurites are thin, highly branched processes that are almost exclusively postsynaptic. Due to the high branching density of dendritiform fibers and the fact that synapses are polyadic, neurites are highly interconnected even within small neuropile volumes. We describe the network motifs most frequently encountered in the Drosophila neuropile. Our study introduces an approach towards a comprehensive anatomical reconstruction of neuronal microcircuitry and delivers microcircuitry comparisons between vertebrate and insect neuropile. PMID:20957184

Fourier-Based Diffraction Analysis of Live Caenorhabditis elegans.

PubMed

Magnes, Jenny; Hastings, Harold M; Raley-Susman, Kathleen M; Alivisatos, Clara; Warner, Adam; Hulsey-Vincent, Miranda

2017-09-13

This manuscript describes how to classify nematodes using temporal far-field diffraction signatures. A single C. elegans is suspended in a water column inside an optical cuvette. A 632 nm continuous wave HeNe laser is directed through the cuvette using front surface mirrors. A significant distance of at least 20-30 cm traveled after the light passes through the cuvette ensures a useful far-field (Fraunhofer) diffraction pattern. The diffraction pattern changes in real time as the nematode swims within the laser beam. The photodiode is placed off-center in the diffraction pattern. The voltage signal from the photodiode is observed in real time and recorded using a digital oscilloscope. This process is repeated for 139 wild type and 108 "roller" C. elegans. Wild type worms exhibit a rapid oscillation pattern in solution. The "roller" worms have a mutation in a key component of the cuticle that interferes with smooth locomotion. Time intervals that are not free of saturation and inactivity are discarded. It is practical to divide each average by its maximum to compare relative intensities. The signal for each worm is Fourier transformed so that the frequency pattern for each worm emerges. The signal for each type of worm is averaged. The averaged Fourier spectra for the wild type and the "roller" C. elegans are distinctly different and reveal that the dynamic worm shapes of the two different worm strains can be distinguished using Fourier analysis. The Fourier spectra of each worm strain match an approximate model using two different binary worm shapes that correspond to locomotory moments. The envelope of the averaged frequency distribution for actual and modeled worms confirms the model matches the data. This method can serve as a baseline for Fourier analysis for many microscopic species, as every microorganism will have its unique Fourier spectrum.

Polarized Light Microscopy

NASA Technical Reports Server (NTRS)

Frandsen, Athela F.

2016-01-01

Polarized light microscopy (PLM) is a technique which employs the use of polarizing filters to obtain substantial optical property information about the material which is being observed. This information can be combined with other microscopy techniques to confirm or elucidate the identity of an unknown material, determine whether a particular contaminant is present (as with asbestos analysis), or to provide important information that can be used to refine a manufacturing or chemical process. PLM was the major microscopy technique in use for identification of materials for nearly a century since its introduction in 1834 by William Fox Talbot, as other techniques such as SEM (Scanning Electron Microscopy), FTIR (Fourier Transform Infrared spectroscopy), XPD (X-ray Powder Diffraction), and TEM (Transmission Electron Microscopy) had not yet been developed. Today, it is still the only technique approved by the Environmental Protection Agency (EPA) for asbestos analysis, and is often the technique first applied for identification of unknown materials. PLM uses different configurations in order to determine different material properties. With each configuration additional clues can be gathered, leading to a conclusion of material identity. With no polarizing filter, the microscope can be used just as a stereo optical microscope, and view qualities such as morphology, size, and number of phases. With a single polarizing filter (single polars), additional properties can be established, such as pleochroism, individual refractive indices, and dispersion staining. With two polarizing filters (crossed polars), even more can be deduced: isotropy vs. anisotropy, extinction angle, birefringence/degree of birefringence, sign of elongation, and anomalous polarization colors, among others. With the use of PLM many of these properties can be determined in a matter of seconds, even for those who are not highly trained. McCrone, a leader in the field of polarized light microscopy, often advised, If you cant determine a specific optical property of a particle after two minutes, move onto another configuration. Since optical properties can be seen so very quickly and easily under polarized light, it is only necessary to spend a maximum of two minutes on a technique to determine a particular property, though often only a few seconds are required.

Study of formation of deep trapping mechanism by UV, beta and gamma irradiated Eu(3+) activated SrY2O4 and Y4Al2O9 phosphors.

PubMed

Dubey, Vikas; Kaur, Jagjeet; Parganiha, Yogita; Suryanarayana, N S; Murthy, K V R

2016-04-01

This paper reports the thermoluminescence properties of Eu(3+) doped different host matrix phosphors (SrY2O4 and Y4Al2O9). The phosphor is prepared by high temperature solid state reaction method. The method is suitable for large scale production and fixed concentration of boric acid using as a flux. The prepared samples were characterized by X-ray diffraction technique and the crystallite size calculated by Scherer's formula. The prepared phosphor characterized by Scanning Electron Microscopic (SEM), Fourier Transform Infrared (FTIR), Energy Dispersive X-ray analysis (EDX), thermoluminescence (TL) and Transmission Electron Microscopic (TEM) techniques. The prepared phosphors for different concentration of Eu(3+) ions were examined by TL glow curve for UV, beta and gamma irradiation. The UV 254nm source used for UV irradiation, Sr(90) source was used for beta irradiation and Co(60) source used for gamma irradiation. SrY2O4:Eu(3+)and Y4Al2O9:Eu(3+) phosphors which shows both higher temperature peaks and lower temperature peaks for UV, beta and gamma irradiation. Here UV irradiated sample shows the formation of shallow trap (surface trapping) and the gamma irradiated sample shows the formation of deep trapping. The estimation of trap formation was evaluated by knowledge of trapping parameters. The trapping parameters such as activation energy, order of kinetics and frequency factor were calculated by peak shape method. Here most of the peak shows second order of kinetics. The effect of gamma, beta and UV exposure on TL studies was also examined and it shows linear response with dose which indicate that the samples may be useful for TL dosimetry. Formation of deep trapping mechanism by UV, beta and gamma irradiated Eu(3+) activated SrY2O4 and Y4Al2O9 phosphors is discussed in this paper. Copyright © 2015 Elsevier Ltd. All rights reserved.

Preparation and thermal stability of the spindle α-Fe{sub 2}O{sub 3}@SiO{sub 2} core–shell nanoparticles

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

Zhang, Xin; Niu, Yongan; Li, Yang

2014-03-15

The spindle α-Fe{sub 2}O{sub 3}@SiO{sub 2} core–shell nanoparticles (NPs) are prepared via hydrothermal synthesis and modified Stöber method. During these processes, shell thicknesses could be easily adjusted by the amount of tetraethylorthosilicate (TEOS), and the formation of core-free SiO{sub 2} could be effectively avoided. The structures and compositions of α-Fe{sub 2}O{sub 3}@SiO{sub 2} NPs are investigated by transmission electron microscope (TEM), X-ray powder diffraction (XRD), Fourier transform infrared spectroscopy (FTIR) and ultraviolet–visible (UV–vis) absorption spectroscopy. These results reveal that the α-Fe{sub 2}O{sub 3}@SiO{sub 2} NPs with certain sizes are monodisperse and homogeneous. To estimate the thermal stability, the α-Fe{sub 2}O{submore » 3}, α-Fe{sub 2}O{sub 3}@SiO{sub 2} and SiO{sub 2} NPs are annealed at 600, 800 and 1000 °C for 1 h under air atmosphere, respectively. Furthermore, the stabilities of these NPs are confirmed by thermal analysis methods. The structure and shape stabilities of these as-prepared α-Fe{sub 2}O{sub 3}@SiO{sub 2} NPs are investigated by XRD and scanning electron microscope (SEM). -- Graphical abstract: Schematic of preparation of the monodisperse spindle α-Fe{sub 2}O{sub 3}@SiO{sub 2} nanoparticles (NPs). Highlights: • The spindle α-Fe{sub 2}O{sub 3}@SiO{sub 2} nanoparticles (NPs) are successfully prepared by hydrothermal synthesis and modified Stöber method. • Optical properties are estimated and calculated by UV vis absorption spectrum. • Thermal stability of the α-Fe{sub 2}O{sub 3}, α-Fe{sub 2}O{sub 3}@SiO{sub 2} and SiO{sub 2} NPs are compared and analyzed by the SEM technique. • The structural changes of α-Fe{sub 2}O{sub 3}@SiO{sub 2} NPs are measured by XRD measurement.« less

Wintertime Experimental investigation of Morphology, Mixing States and Columnar Optical Properties of Aerosols over a Desert location in India

NASA Astrophysics Data System (ADS)

Mishra, S.; Kumar, T.; Sharma, C.; Prasad, M. V. S. N.; Singh, S.; Agnihotri, R.; Arya, B. C.; Gupta, B.; Naaraayanan, T.; Gautam, S.; Kumar, D.; Sood, K. N.; Tawale, J. S.; Sharma, A. K.; Mitra, A. K.

2014-12-01

Indian Desert (The Thar Desert) is considered as the source of mineral dust in the Indo-Gangetic Plain (IGP) especially in pre-monsoon period due to large scale convective activities during hot summer. To study the physico-chemical characteristics of aerosols over the Thar Desert (Jaisalmer, Rajasthan) during winter (December, 2013), a field campaign has been carried out in Jaisalmer in Rajasthan state. Experiments were conducted inside the city as well as far from the city. The faraway location is close to international border of another country i.e. Pakistan. PM2.5 and PM10 were collected within the city while PM5 was collected far from the city. Particles were collected on Teflon filters for bulk analysis with Fourier Transform Infrared Spectroscopy (FTIR), on Tin substrate for individual particle morphology and elemental composition analysis with Scanning Electron Microscope (SEM) equipped with Energy Dispersive Spectrometer (EDS) and on the Cu-TEM grid for individual particle morphology and mixing state characterization using High Resolution-Transmission Electron Microscope (HRTEM). Together with this, aerosol size distribution observation and columnar spectral aerosol optical properties have been carried out with OPC (Optical Particle Counter, GRIMM Model 1.108) and hand held Microtops-II, respectively. HRTEM analysis reveals occurrence of carbonaceous fractals found in various mixing states 1) aged with some hygroscopic species 2) embedded in sulfate host 3) semi-externally mixed with sulfate and other species. Core-shell particles were also observed with varying core composition (carbon, typical mineral dust, and calcite) and shell thickness (shell comprising of water). The back trajectory analysis reveals the source of wind from Karachi and Islamabad from Pakistan which may be the potential source of carbonaceous species over the sampling site. SEM-EDS analysis reveals occurrence of mineral dust 1) pure mineral dust (Ca and Si rich) 2) polluted mineral dust (mixed with carbon and Cr) together with some pollutants (rich in carbon, S, K, Cl, Mo and Nb). Signatures of various organics were traced using FTIR. Aerosol columnar spectral optical properties, size distribution and meteorology in tandem with aforementioned aerosol properties will be discussed in detail during the presentation.

Synthesis and characterization of the core-shell magnetic molecularly imprinted polymers (Fe₃O₄@MIPs) adsorbents for effective extraction and determination of sulfonamides in the poultry feed.

PubMed

Kong, Xuan; Gao, Ruixia; He, Xiwen; Chen, Langxing; Zhang, Yukui

2012-07-06

In this study, we present a general method to prepare the core-shell magnetic molecularly imprinted polymers (MIPs) nanoparticles (NPs) for sulfamethazine (SMZ). The resulting Fe₃O₄@MIPs NPs possess a highly improved imprinting effect, fast adsorption kinetics and high adsorption capacity, and can be applied to extract sulfonamide in the poultry feed. In this protocol, the magnetite NPs were synthesized by co-precipitating Fe²⁺ and Fe³⁺ in an ammonia solution first. Silica was then coated on the Fe₃O₄ NPs using a sol-gel method to obtain silica shell magnetic NPs. Subsequently, the vinyl groups were grated onto silica-modified Fe₃O₄ surface by 3-methacryloyloxypropyltrimethoxysilane. Finally, the MIPs films were formed on the surface of Fe₃O₄@SiO₂ by the copolymerization of vinyl end groups with functional monomer, methacrylic acid, cross-linking agent, ethylene glycol dimethacrylate, the initiator azo-bis-isobutyronitrile and template molecule, sulfamethazine. The morphology, magnetic, adsorption and recognition properties of Fe₃O₄@MIPs NPs were characterized using transmission electron microscope (TEM), scanning electron microscope (SEM), Fourier transform infrared (FT-IR) spectrometer, vibrating sample magnetometer (VSM) and re-binding experiments. The results showed that the binding sites of Fe₃O₄@MIPs were good accessibility, fast adsorption rate and the maximum adsorption capacity of Fe₃O₄@MIPs to SMZ was 344.8 μg g⁻¹. The selectivity of the obtained Fe₃O₄@MIPs NPs were elucidated by the different rebinding capability of SMZ and structural related sulfonamides in the mixed solution. The results indicated that the Fe₃O₄@MIPs had high imprinting factor 9.5 and significant selectivity. A method was developed for enrichment and determination of SMZ in the poultry feed samples with recoveries of duck and chicken feed ranging from 63.3 to 76.5% and 68.7 to 74.7%, respectively and the relative standard deviations (RSD) (<6.7%). Copyright © 2012 Elsevier B.V. All rights reserved.

Microscopic observations of osteoblast growth on micro-arc oxidized β titanium

NASA Astrophysics Data System (ADS)

Chen, Hsien-Te; Chung, Chi-Jen; Yang, Tsai-Ching; Tang, Chin-Hsin; He, Ju-Liang

2013-02-01

Titanium alloys are widely used in orthopedic and dental implants, owing to their excellent physical properties and biocompatibility. By using the micro-arc oxidation (MAO), we generated anatase-rich (A-TiO2) and rutile-rich (R-TiO2) titanium dioxide coatings, individually on β-Ti alloy, in which the latter achieved an enhanced in vitro and in vivo performance. Thoroughly elucidating how the osteoblasts interact with TiO2 coatings is of worthwhile interest. This study adopts the focused ion beam (FIB) to section off the TiO2 coated samples for further scanning electron microscope (SEM) and transmission electron microscope (TEM) observation. The detailed crystal structures of the TiO2 coated specimens are also characterized. Experimental results indicate osteoblasts adhered more tenaciously and grew conformably with more lamellipodia extent on the R-TiO2 specimen than on the A-TiO2 and raw β-Ti specimens. FIB/SEM cross-sectional images of the cell/TiO2 interface revealed micro gaps between the cell membrane and contact surface of A-TiO2 specimen, while it was not found on the R-TiO2 specimen. Additionally, the number of adhered and proliferated cells on the R-TiO2 specimen was visually greater than the others. Closely examining EDS line scans and elemental mappings of the FIB/TEM cross-sectional images of the cell/TiO2 interface reveals both the cell body and interior space of the TiO2 coating contain nitrogen and sulfur (the biological elements in cell). This finding supports the assumption that osteoblast can grow into the porous structure of TiO2 coatings and demonstrating that the R-TiO2 coating formed by MAO serves the best for β-Ti alloys as orthopedic and dental implants.

Surface functionalization of hexagonal boron nitride and its effect on the structure and performance of composites

NASA Astrophysics Data System (ADS)

Jin, Wenqin; Zhang, Wei; Gao, Yuwen; Liang, Guozheng; Gu, Aijuan; Yuan, Li

2013-04-01

A new organized hexagonal boron nitride (OhBN) with significantly increased amount of amine groups was synthesized, and characterized by Fourier Transform Infrared (FTIR), X-ray Photoelectron Spectroscopy (XPS), Thermogravimetric (TG) analysis, UV-vis Transmittance Spectra, Transmission Electron Microscope (TEM) and the potentiometric titration. The content of amine groups for OhBN is about 5 times of that for original hexagonal boron nitride (hBN). Based on the preparation of OhBN, new composites consisting of OhBN and bismaleimide (BD) resin were developed, which show greatly improved integrated performance (including dynamic mechanical, dielectric and thermal properties) compared with BD resin and the hBN/BD composites. In the case of the OhBN/BD composite with 15 wt% OhBN, its storage modulus, dielectric loss, thermal conductivity and coefficient of thermal expansion are about 1.2, 0.56, 1.11 and 0.92 times of the corresponding values of hBN/BD composite, respectively; moreover, the glass transition temperature of the former is 15 °C higher than that of the latter. These interesting results suggest that the integrated performance of the composites is closely related to the surface nature of the fillers because the change in the surface nature not only varies the chemical structure, free volume and crosslinking density of the composite, but also determines the interfacial nature between inorganic fillers and the resin matrix. This investigation demonstrates that the method proposed herein provides a new approach to prepare organized inorganic fillers as well as corresponding composites with controlled structure and expected performances for cutting-edge industries.

Synthesis and characterization of novel Cu(II) complex coated Fe3O4@SiO2 nanoparticles for catalytic performance

NASA Astrophysics Data System (ADS)

Nasrollahzadeh, Mahmoud; Sajjadi, Mohaddeseh; Khonakdar, Hossein Ali

2018-06-01

In this study, a convenient method for the synthesis of arylaminotetrazoles has been developed using a copper (II)-aminotetrazole complex immobilized on silica-coated Fe3O4 (Fe3O4@SiO2) nanoparticles (Fe3O4@SiO2-aminotet-Cu(II)) as a novel and efficient magnetically catalyst. The constructed superparamagnetic core-shell nanoparticles were successfully prepared, as proven using different spectroscopic techniques such as fourier-transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD), transmission electron microscope (TEM), field emission scanning electron microscopy (FESEM), energy dispersive X-ray spectroscopy (EDS), thermogravimetry and differential thermogravimetry (TG-DTG) and vibrating sample magnetometer (VSM) analysis. The applicability of Fe3O4@SiO2-aminotet-Cu(II) magnetic catalyst allows the efficient synthesis of a variety of arylaminotetrazoles from the reaction between various arylcyanamides with sodium azide in high yields. The effect of catalyst loading was investigated. In addition, the reaction mechanism for the synthesis of arylaminotetrazoles was reasonably proposed. Results show that the 1-aryl-5-amino-1H-tetrazole (B isomer) and 5-arylamino-1H-tetrazole (A isomer) can be obtained from the arylcyanamides carrying electron-donating and electron-withdrawing substituents, respectively. This procedure offers a simple methodology, relatively short reaction times, easy work-up, high yields of the products and a cleaner reaction with elimination of hydrazoic acid (HN3). Moreover, catalyst can be conveniently recovered through the use of external magnet and reused for at least 6 times without any significant loss of its activity.

Quaternized Carboxymethyl Chitosan-Based Silver Nanoparticles Hybrid: Microwave-Assisted Synthesis, Characterization and Antibacterial Activity.

PubMed

Huang, Siqi; Wang, Jing; Zhang, Yang; Yu, Zhiming; Qi, Chusheng

2016-06-17

A facile, efficient, and eco-friendly approach for the preparation of uniform silver nanoparticles (Ag NPs) was developed. The synthesis was conducted in an aqueous medium exposed to microwave irradiation for 8 min, using laboratory-prepared, water-soluble quaternized carboxymethyl chitosan (QCMC) as a chemical reducer and stabilizer and silver nitrate as the silver source. The structure of the prepared QCMC was characterized using Fourier transform infrared (FT-IR) and ¹H nuclear magnetic resonance (NMR). The formation, size distribution, and dispersion of the Ag NPs in the QCMC matrix were determined using X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), ultraviolet-visible (UV-Vis), transmission electron microscopy (TEM), and field emission scanning electron microscope (FESEM) analysis, and the thermal stability and antibacterial properties of the synthesized QCMC-based Ag NPs composite (QCMC-Ag) were also explored. The results revealed that (1) QCMC was successfully prepared by grafting quaternary ammonium groups onto carboxymethyl chitosan (CMC) chains under microwave irradiation in water for 90 min and this substitution appeared to have occurred at -NH₂ sites on C2 position of the pyranoid ring; (2) uniform and stable spherical Ag NPs could be synthesized when QCMC was used as the reducing and stabilizing agent; (3) Ag NPs were well dispersed in the QCMC matrix with a narrow size distribiution in the range of 17-31 nm without aggregation; and (4) due to the presence of Ag NPs, the thermal stability and antibacterial activity of QCMC-Ag were dramatically improved relative to QCMC.

Cytotoxicity study of Piper nigrum seed mediated synthesized SnO2 nanoparticles towards colorectal (HCT116) and lung cancer (A549) cell lines.

PubMed

Tammina, Sai Kumar; Mandal, Badal Kumar; Ranjan, Shivendu; Dasgupta, Nandita

2017-01-01

Different sized tetragonal tin oxide nanoparticles (SnO 2 NPs) were synthesized using Piper nigrum seed extract at three different calcination temperatures (300, 500, 900°C) and these nanoparticles (NPs) were characterized by transmission electron microscopy (TEM), X-ray diffraction (XRD), dynamic light scattering (DLS) and Fourier transform infrared spectrophotometry (FT-IR). The optical properties were studied using UV-Vis and photoluminescence (PL) spectrophotometers. The generation of reactive oxygen species (ROS) was monitored by using a fluorescence spectrophotometer and fluorescence microscope. The cytotoxicity of the synthesized SnO 2 NPs was checked against the colorectal (HCT116) and lung (A549) cancer cell lines and the study results show that SnO 2 NPs were toxic against cancer cell lines depending on their size and dose. IC 50 values of SnO 2 NPs having average particle sizes of 8.85±3.5, 12.76±3.9 and 29.29±10.9nm are 165, 174 and 208μgL -1 against HCT116, while these values are 135, 157 and 187μgL -1 against A549 carcinoma cell lines, respectively. The generated ROS were responsible for the cytotoxicity of SnO 2 NPs to the studied cancer cells and smaller size NPs generated more ROS and hence showed higher cytotoxicity over larger size NPs. The results of this study suggest that the synthesized stable nanoparticles could be a potent therapeutic agent towards cancerous cell lines. Copyright © 2016 Elsevier B.V. All rights reserved.

Modifying surface properties of KIT-6 zeolite with Ni and V for enhancing catalytic CO methanation

NASA Astrophysics Data System (ADS)

Cao, Hong-Xia; Zhang, Jun; Guo, Cheng-Long; Chen, Jingguang G.; Ren, Xiang-Kun

2017-12-01

The surface of the KIT-6 zeolite was modified with different amounts of Ni and V to promote the catalytic properties for CO methanation. A series of xNi-yV/KIT-6 with various Ni and V contents were prepared by the incipient-wetness impregnation method. The modified surfaces were characterized using N2 adsorption-desorption, Brunauer-Emmett-Teller (BET), X-ray diffraction (XRD), hydrogen temperature-programmed reduction (H2-TPR), Fourier transformed infrared spectroscopy (FT-IR), Raman, X-ray photoelectron spectroscopy (XPS), transmission electron microscope (TEM), and energy-dispersive X-ray spectroscopy (EDX), respectively. The characterization results illustrated that the modification of V species was able to significantly promote low-temperature catalytic performance below 350 °C compared to that of unmodified Ni/KIT-6, which was likely due to an increase in the H2 uptake accompanied by enhanced CO dissociation derived from stronger electron transfer from V species to Ni0. Correspondingly, the xNi-yV/KIT-6 catalysts exhibited a distinct enhancement in CO conversion, CH4 selectivity and CH4 yield over unmodified Ni/KIT-6. Among all catalysts, 20Ni-2V/KIT-6 showed the best catalytic performance, corresponding to nearly 100% CO conversion and 85% CH4 yield at a low temperature of 300 °C. Furthermore, 20Ni-2V/KIT-6 presented enhanced coking-resistant and anti-sintering properties during a 60h-lifetime test at 500 °C and 1 atm with a high weight hourly space velocity (WHSV) of 60000 ml/g/h.

Synthesis, structural and optical properties of ZnO spindle/reduced graphene oxide composites with enhanced photocatalytic activity under visible light irradiation

NASA Astrophysics Data System (ADS)

Prabhu, S.; Pudukudy, M.; Sohila, S.; Harish, S.; Navaneethan, M.; Navaneethan, D.; Ramesh, R.; Hayakawa, Y.

2018-05-01

In the present work, spindle-shaped ZnO and reduced graphene oxide sheets were successfully synthesized by a hydrothermal method and then ZnO/r-GO composite was prepared by a direct solution mixing method. Various characterization results confirmed the interior and surface decoration of spindle-shaped ZnO on the reduced graphene oxide sheets. The phase formation, crystalline structure, morphology, surface states and optical properties were characterized using Powder X-ray diffraction (XRD), Field emission scanning electron microscopy (FESEM), Transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), Fourier Transform Infrared Spectroscopy (FTIR) and UV-Vis spectroscopy. The X-ray diffraction analysis showed the formation of the hexagonal wurtzite crystalline structure of ZnO with high crystalline quality. The band gap of the ZnO/r-GO composite was found to be low (3.03eV) compared to the band gap of spindle shaped ZnO (3.13 eV), as calculated from optical studies. The spindle-like morphology of the single crystalline ZnO was clearly shown in the electron microscopic images. The chemical bonding and surface states of the samples were studied using XPS measurement. Moreover, a possible growth mechanism for the ZnO spindle was proposed. The catalytic activity of the as-synthesized samples was evaluated for the photodegradation of methylene blue under visible light irradiation. Among the synthesized samples, the ZnO/r-GO composite showed higher degradation efficiency of 93% and successfully reused for four consecutive run without any activity loss.

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.

Evidence of Collisional Histories of Asteroids, Comets and Meteorites: Comparisons with Shocked Minerals

NASA Technical Reports Server (NTRS)

Lederer, Susan M.; Jensen, Elizabeth; Smith, Douglas; Fane, Michael; Whizin, Akbar; Landsman, Zoe A.; Wooden, Diane H.; Lindsay, Sean S.; Cintala, Mark; Keller, Lindsay P.;

Visible light responsive sulfated rare earth doped TiO(2)@fumed SiO(2) composites with mesoporosity: enhanced photocatalytic activity for methyl orange degradation.

PubMed

Zhan, Changchao; Chen, Feng; Yang, Jintao; Dai, Daoxing; Cao, Xiaohua; Zhong, Mingqiang

2014-02-28

Visible light (VL) responsive mesoporous sulfated rare earth ions (Nd(3+), La(3+), Y(3+)) incorporated TiO2@fumed SiO2 photocatalysts were prepared by sol-gel method with P123 (EO20PO70EO20) as a template. The resultant samples were characterized by X-ray diffraction (XRD), transmission electron microscope (TEM), X-ray photoelectron spectroscopy (XPS), N2 adsorption-desorption measurements (BET), UV-vis diffuse reflectance spectroscopy, photoluminescence (PL) spectra, Fourier transform infrared spectroscopy (FTIR) and thermal analyses (TG-DTA). In comparison with nondoped sample, RE-doped samples showed not only an increase in the surface areas and pore volumes, but also an inhibition of titania phase transition from anatase to rutile. Photo-degradation results revealed that RE-doped samples could greatly improve the photocatalytic activity, and the experimental degradation rates of methyl orange (MO) were higher than that catalyzed by undoped samples and Degussa P-25, obeyed the order of Nd(3+)>La(3+)>Y(3+). Nd-doped sample expressed the highest photoactivity and the optimal dosage was 0.25mol%, which resulted in MO degradation rates of 99.8% and 90.05% irradiation under UV for 60min and VL (λ>400nm) for 40h, respectively. The enhanced photocatalytic activity could be attributed to the higher specific area, good crystallinity, strong VL absorption and effective separation of photogenerated electron-hole pairs in the catalyst. Copyright © 2014 Elsevier B.V. All rights reserved.

Quantum dots and ionic liquid-sensitized effect as an efficient and green catalyst for the sensitive determination of glucose.

PubMed

Azizi, Seyed Naser; Chaichi, Mohammad Javad; Shakeri, Parmis; Bekhradnia, Ahmadreza

2015-07-05

A novel fluorescence (FL) method using water-soluble CdSe quantum dots (QDs) is proposed for the fluorometric determination of hydrogen peroxide and glucose. Water-soluble CdSe QDs were synthesized by using thioglycolic acid as stabilizer in aqueous solutions. The nanoparticles were structurally and optically characterized by X-ray powder diffraction (XRD), dynamic light scattering (DLS), Fourier transform infrared spectroscopy (FTIR), UV-Vis absorption spectroscopy, photoluminescence (PL) emission spectroscopy and transmission electron microscope (TEM). Ionic liquid-sensitized effect in aqueous solution was then investigated. In the presence of ionic liquid as catalyst, H2O2 was decomposed into radical that could quench the fluorescence of CdSe QDs more efficiently and rapidly. Then the oxidization of glucose by glucose oxidase was coupled with the fluorescence quenching of CdSe QDs by H2O2 producer with ionic liquid catalyst, which can be used to detect glucose. Therefore, a new FL analysis system was developed for the determination of glucose. Under the optimum conditions, there is a good linear relationship between the relative PL emission intensity and the concentration of glucose in the range of 5.0×10(-7)-1.0×10(-4) M of glucose with a correlation coefficient (R(2)) of 0.9973. The limit of detection of this system was found to be 1.0×10(-7) M. This method is not only simple, sensitive and low cost, but also reliable for practical applications. Copyright © 2015. Published by Elsevier B.V.

Development of facile drug delivery platform of ranibizumab fabricated PLGA-PEGylated magnetic nanoparticles for age-related macular degeneration therapy.

PubMed

Yan, Jian; Peng, Xifeng; Cai, Yulian; Cong, Wendong

2018-06-01

The present anti-angiogenic therapies for neovascular age-related macular degeneration require effective drug delivery systems for transfer drug molecules. Ranibizumab is an active humanized monoclonal antibody that counteracts active forms of vascular endothelial growth factor A in the neovascular age-related macular degeneration therapy. The development of ranibizumab-related therapies, we have designed the effective drug career with engineered magnetic nanoparticles (Fe 3 O 4 ) as a facile platform of ranibizumab delivery for the treatment of neovascular age-related macular degeneration. Ranibizumab conjugated iron oxide (Fe 3 O 4 )/PEGylated poly lactide-co-glycolide (PEG-PLGA) was successfully designed and the synthesized materials are analyzed different analytical techniques. The microscopic techniques (Scanning Electron Microscopy (SEM) & Transmission Electron Microscopy (TEM)) are clearly displayed that spherical nanoparticles into the PEG-PLGA matrix and presence of elements and chemical interactions confirmed by the results of energy dispersive X-ray analysis (EDX) and Fourier trans-form infrared (FTIR) spectroscopic methods. The in vitro anti-angiogenic evaluation of Fe 3 O 4 /PEG-PLGA polymer nanomaterial efficiently inhibits the tube formation in the Matrigel-based assay method by using human umbilical vein endothelial cells. Ranibizumab treated Fe 3 O 4 /PEG-PLGA polymer nanomaterials not disturbed cell proliferation and the results could not display the any significant differences in human endothelial cells. The present investigated results describe that Fe 3 O 4 /PEG-PLGA polymer nanomaterials can be highly favorable and novel formulation for the treatment of neovascular age-related macular degeneration. Copyright © 2018 Elsevier B.V. All rights reserved.

An evidence on G2/M arrest, DNA damage and caspase mediated apoptotic effect of biosynthesized gold nanoparticles on human cervical carcinoma cells (HeLa)

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

Jeyaraj, M.; Arun, R.; Sathishkumar, G.

2014-04-01

Highlights: • Gold nanoparticles (AuNPs) have been synthesized using Podophyllum hexandrum L. • AuNPs induces the oxidative stress to cell death in human cervical carcinoma cells. • It activates the caspase-cascade to cellular death. • It is actively blocks G2/M phase of cell cycle. - Abstract: Current prospect of nanobiotechnology involves in the greener synthesis of nanostructured materials particularly noble metal nanoparticles for various biomedical applications. In this study, biologically (Podophyllum hexandrum L.) synthesized crystalline gold nanoparticles (AuNPs) with the size range between 5 and 35 nm were screened for its anticancereous potential against human cervical carcinoma cells (HeLa). Stoichiometricmore » proportion of the reaction mixture and conditions were optimized to attain stable nanoparticles with narrow size range. Different high throughput techniques like transmission electron microscope (TEM), X-ray diffraction (XRD) and UV–vis spectroscopy were adopted for the physio-chemical characterization of AuNPs. Additionally, Fourier transform infrared spectroscopy (FTIR) study revealed that the water soluble fractions present in the plant extract solely influences the reduction of AuNPs. Sublimely, synthesized AuNPs exhibits an effective in vitro anticancer activity against HeLa cells via induction of cell cycle arrest and DNA damage. Furthermore, it was evidenced that AuNPs treated cells are undergone apoptosis through the activation of caspase cascade which subsequently leads to mitochondrial dysfunction. Thereby, this study proves that biogenic colloidal AuNPs can be developed as a promising drug candidature for human cervical cancer therapy.« less

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

The core contribution of transmission electron microscopy to functional nanomaterials engineering

NASA Astrophysics Data System (ADS)

Carenco, Sophie; Moldovan, Simona; Roiban, Lucian; Florea, Ileana; Portehault, David; Vallé, Karine; Belleville, Philippe; Boissière, Cédric; Rozes, Laurence; Mézailles, Nicolas; Drillon, Marc; Sanchez, Clément; Ersen, Ovidiu

2016-01-01

Research on nanomaterials and nanostructured materials is burgeoning because their numerous and versatile applications contribute to solve societal needs in the domain of medicine, energy, environment and STICs. Optimizing their properties requires in-depth analysis of their structural, morphological and chemical features at the nanoscale. In a transmission electron microscope (TEM), combining tomography with electron energy loss spectroscopy and high-magnification imaging in high-angle annular dark-field mode provides access to all features of the same object. Today, TEM experiments in three dimensions are paramount to solve tough structural problems associated with nanoscale matter. This approach allowed a thorough morphological description of silica fibers. Moreover, quantitative analysis of the mesoporous network of binary metal oxide prepared by template-assisted spray-drying was performed, and the homogeneity of amino functionalized metal-organic frameworks was assessed. Besides, the morphology and internal structure of metal phosphide nanoparticles was deciphered, providing a milestone for understanding phase segregation at the nanoscale. By extrapolating to larger classes of materials, from soft matter to hard metals and/or ceramics, this approach allows probing small volumes and uncovering materials characteristics and properties at two or three dimensions. Altogether, this feature article aims at providing (nano)materials scientists with a representative set of examples that illustrates the capabilities of modern TEM and tomography, which can be transposed to their own research.Research on nanomaterials and nanostructured materials is burgeoning because their numerous and versatile applications contribute to solve societal needs in the domain of medicine, energy, environment and STICs. Optimizing their properties requires in-depth analysis of their structural, morphological and chemical features at the nanoscale. In a transmission electron microscope (TEM), combining tomography with electron energy loss spectroscopy and high-magnification imaging in high-angle annular dark-field mode provides access to all features of the same object. Today, TEM experiments in three dimensions are paramount to solve tough structural problems associated with nanoscale matter. This approach allowed a thorough morphological description of silica fibers. Moreover, quantitative analysis of the mesoporous network of binary metal oxide prepared by template-assisted spray-drying was performed, and the homogeneity of amino functionalized metal-organic frameworks was assessed. Besides, the morphology and internal structure of metal phosphide nanoparticles was deciphered, providing a milestone for understanding phase segregation at the nanoscale. By extrapolating to larger classes of materials, from soft matter to hard metals and/or ceramics, this approach allows probing small volumes and uncovering materials characteristics and properties at two or three dimensions. Altogether, this feature article aims at providing (nano)materials scientists with a representative set of examples that illustrates the capabilities of modern TEM and tomography, which can be transposed to their own research. Electronic supplementary information (ESI) available. See DOI: 10.1039/c5nr05460e

Unravelling the secret of seed-based gels in water: the nanoscale 3D network formation.

PubMed

Samateh, Malick; Pottackal, Neethu; Manafirasi, Setareh; Vidyasagar, Adiyala; Maldarelli, Charles; John, George

2018-05-09

Chia (Salvia hispanica) and basil (Ocimum basilicum) seeds have the intrinsic ability to form a hydrogel concomitant with moisture-retention, slow releasing capability and proposed health benefits such as curbing diabetes and obesity by delaying digestion process. However, the underlying mode of gelation at nanoscopic level is not clearly explained or explored. The present study elucidates and corroborates the hypothesis that the gelling behavior of such seeds is due to their nanoscale 3D-network formation. The preliminary study revealed the influence of several conditions like polarity, pH and hydrophilicity/hydrophobicity on fiber extrusion from the seeds which leads to gelation. Optical microscopic analysis clearly demonstrated bundles of fibers emanating from the seed coat while in contact with water, and live growth of fibers to form 3D network. Scanning electron microscope (SEM) and transmission electron microscope (TEM) studies confirmed 3D network formation with fiber diameters ranging from 20 to 50 nm.

Investigation of Microstructural Features Determining the Toughness of 980 MPa Bainitic Weld Metal

NASA Astrophysics Data System (ADS)

Cao, R.; Zhang, X. B.; Wang, Z.; Peng, Y.; Du, W. S.; Tian, Z. L.; Chen, J. H.

2014-02-01

The microstructural features that control the impact toughness of weld metals of a 980 MPa 8 pct Ni high-strength steel are investigated using instrumented Charpy V tester, optical microscope (OM), scanning electron microscope (SEM), transmission electron microscope (TEM), electron back-scattered diffraction (EBSD), and finite-element method (FEM) calculation. The results show that the critical event for cleavage fracture in this high-strength steel and weld metals is the propagation of a bainite packet-sized crack across the packet boundary into contiguous packets, and the bainitic packet sizes control the impact toughness. The high-angle misorientation boundaries detected in a bainite packet by EBSD form fine tear ridges on fracture surfaces. However, they are not the decisive factors controlling the cleavage fracture. The effects of Ni content are essential factors for improving the toughness. The extra large cleavage facets seriously deteriorate the toughness, which are formed on the interfaces of large columnar crystals growing in welding pools with high heat input.

Microstructure Evolution and Mechanical Properties of Mg-14%Li-1%Al Alloy During the High-Pressure Torsion

NASA Astrophysics Data System (ADS)

Tian, Chenguang; Lu, Huimin; Zhao, Liyuan

The super-light LA141 (Mg-14%Li-1%Al) alloy was produced and processed by high-pressure torsion (HPT) under the imposed pressure of 3 GPa and different shear strains γ through 3, 6, 9 and 12 turns at room temperature (RT). The microstructure evolution of the alloy during the HPT treatment was investigated by transmission electron microscope (TEM) and optical microscope (OM). It turned out that the grains were substantially refined, and the optical microscope revealed that the grains of HPT processed samples at the edge of the disc were finer by comparison with the ones near the center of the disc. Later, Vickers indentation analysis was used to evaluate the micro-hardness of deformed samples, and tension test was employed to obtain the strength and elongation at room temperature. The results indicated that the micro-hardness and tensile strength had increased to a certain extent, and the elongation had been significantly improved.

Microstructural Study of 17-4PH Stainless Steel after Plasma-Transferred Arc Welding.

PubMed

Deng, Dewei; Chen, Rui; Sun, Qi; Li, Xiaona

2015-01-29

The improvement of the surface qualities and surface hardening of precipitation hardened martensitic stainless steel 17-4PH was achieved by the plasma-transferred arc welding (PTAW) process deposited with Co-based alloy. The microstructure of the heat affected zone (HAZ) and base metal were characterized by optical microscope (OM), scanning electron microscope (SEM) and transmission electron microscope (TEM). The results show that there are obvious microstructural differences between the base metal and HAZ. For example, base material is transformed from lath martensite to austenite due to the heateffect of the welding process. On the other hand, the precipitate in the matrix (bar-like shape Cr₇C₃ phase with a width of about one hundred nanometres and a length of hundreds of nanometres) grows to a rectangular appearance with a width of about two hundred nanometres and a length of about one micron. Stacking fault could also be observed in the Cr₇C₃ after PTAW. The above means that welding can obviously improve the surface qualities.

Evaluation of Resuscitation Fluids on Endothelial Glycocalyx, Venular Blood Flow, and Coagulation Function After Hemorrhagic Shock in Rats

DTIC Science & Technology

2013-10-01

thrombin inhibition, leading to coagulopathy. Using intravital microscopy, we have obtained direct in vivo data showing glycocalyx thickness reduction...collected in 3.2% citrate for coagulation assays (ROTEM, TEM Innovations GmbH, Munich, Germany). Intravital Microscopy The system described in detail...microscopic fields containing venules were randomly selected. The first dye (TR-Dx70) was injected 5 min before baseline. Image sequences of

Experimental and simulation studies on the behavior of signal harmonics in magnetic particle imaging.

PubMed

Murase, Kenya; Konishi, Takashi; Takeuchi, Yuki; Takata, Hiroshige; Saito, Shigeyoshi

2013-07-01

Our purpose in this study was to investigate the behavior of signal harmonics in magnetic particle imaging (MPI) by experimental and simulation studies. In the experimental studies, we made an apparatus for MPI in which both a drive magnetic field (DMF) and a selection magnetic field (SMF) were generated with a Maxwell coil pair. The MPI signals from magnetic nanoparticles (MNPs) were detected with a solenoid coil. The odd- and even-numbered harmonics were calculated by Fourier transformation with or without background subtraction. The particle size of the MNPs was measured by transmission electron microscopy (TEM), dynamic light-scattering, and X-ray diffraction methods. In the simulation studies, the magnetization and particle size distribution of MNPs were assumed to obey the Langevin theory of paramagnetism and a log-normal distribution, respectively. The odd- and even-numbered harmonics were calculated by Fourier transformation under various conditions of DMF and SMF and for three different particle sizes. The behavior of the harmonics largely depended on the size of the MNPs. When we used the particle size obtained from the TEM image, the simulation results were most similar to the experimental results. The similarity between the experimental and simulation results for the even-numbered harmonics was better than that for the odd-numbered harmonics. This was considered to be due to the fact that the odd-numbered harmonics were more sensitive to background subtraction than were the even-numbered harmonics. This study will be useful for a better understanding, optimization, and development of MPI and for designing MNPs appropriate for MPI.

Preparation and characterization of ultrafine nanoparticles of Cu doped lithium tetraborate

NASA Astrophysics Data System (ADS)

Khalilzadeh, Nasrin; Saion, Elias Bin; Mirabolghasemi, Hamed; Crouse, Karen A.; Shaari, Abdul Halim Bin; Hashim, Mansor Bin

This study details an innovative single-step thermal synthesis of nano-sized lithium tetraborate doped with 0.1 %wt copper and its characterization. The heating temperature for the synthesis of the nanoparticle material was optimized by variation between 200 and 850 °C. The optimum amount of polyvinyl pyrrolidone (PVP) the capping agent was determined to be 0.027 mol per 1 g LTB-Cu. The calcination time was 2 h. Characterization of the samples was carried out using Thermogravimetry Analysis (TGA), Derivative Thermogravimetry (DTG), Differential Scanning Calorimetry (DSC), Fourier Transform Infrared (FTIR) Spectroscopy, X-ray diffractometer (XRD), transmission electron microscopy (TEM) and Ultraviolet-Visible (UV-Vis) spectroscopy. The product was thermally stable above 450 °C. FTIR, XRD and TEM results confirmed the formation of pure nano-crystalline copper doped lithium tetraborate between 450 and 750 °C. The optical bandgap was estimated to be 5.02-6.05 eV in the presence of different amounts of PVP at various calcination temperatures.

Synthesis of High Valence Silver-Loaded Mesoporous Silica with Strong Antibacterial Properties

PubMed Central

Chen, Chun-Chi; Wu, Hsin-Hsien; Huang, Hsin-Yi; Liu, Chen-Wei; Chen, Yi-Ning

2016-01-01

A simple chemical method was developed for preparing high valence silver (Ag)-loaded mesoporous silica (Ag-ethylenediaminetetraacetic acid (EDTA)-SBA-15), which showed strong antibacterial activity. Ag-EDTA-SBA-15 exhibited stronger and more effective antibacterial activity than commercial Ag nanoparticles did, and it offered high stability of high valence silver in the porous matrix and long-lasting antibacterial activity. The synthesized materials were characterized using Fourier transform infrared spectroscopy, powder X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS) analysis, and transmission electron microscopy (TEM). Ag existed in both surface complexation and Ag particles. EDTA anchored within a porous structure chelated Ag ions in higher oxidation states and prevented their agglomeration and oxidation reduction. The XRD results showed that most Ag in the Ag-EDTA-SBA-15 existed in higher oxidation states such as Ag(II) and Ag(III). However, the XPS and TEM results showed that Ag easily reduced in lower oxidation states and agglomerated as Ag particles on the exterior layer of the SBA-15. PMID:26742050

Photoluminescence of etched SiC nanowires

NASA Astrophysics Data System (ADS)

Stewart, Polite D., Jr.; Rich, Ryan; Zerda, T. W.

2010-10-01

SiC nanowires were produced from carbon nanotubes and nanosize silicon powder in a tube furnace at temperatures between 1100^oC and 1350^oC. SiC nanowires had average diameter of 30 nm and very narrow size distribution. The compound possesses a high melting point, high thermal conductivity, and excellent wear resistance. The surface of the SiC nanowires after formation is covered by an amorphous layer. The composition of that layer is not fully understood, but it is believed that in addition to amorphous SiC it contains various carbon and silicon compounds, and SiO2. The objective of the research was to modify the surface structure of these SiC nanowires. Modification of the surface was done using the wet etching method. The etched nanowires were then analyzed using Fourier Transform Infrared spectroscopy (FTIR), transmission electron microscopy (TEM), and photoluminescence (PL). FTIR and TEM analysis provided valid proof that the SiC nanowires were successfully etched. Also, the PL results showed that the SiC nanowire core did possess a fluorescent signal.

Production of new cellulose nanomaterial from red algae marine biomass Gelidium elegans.

PubMed

Chen, You Wei; Lee, Hwei Voon; Juan, Joon Ching; Phang, Siew-Moi

2016-10-20

Nanocellulose was successfully isolated from Gelidium elegans red algae marine biomass. The red algae fiber was treated in three stages namely alkalization, bleaching treatment and acid hydrolysis treatment. Morphological analysis was performed by field emission scanning electron microscopy (FESEM) and transmission electron microscopy (TEM). TEM results revealed that the isolated nanocellulose had the average diameter and length of 21.8±11.1nm and of 547.3±23.7nm, respectively. Fourier transform infrared (FTIR) spectroscopy proved that the non-cellulosic polysaccharides components were progressively removed during the chemically treatment, and the final derived materials composed of cellulose parent molecular structure. X-ray diffraction (XRD) study showed that the crystallinity of yielded product had been improved after each successive treatments subjected to the treated fiber. The prepared nano-dimensional cellulose demonstrated a network-like structure with higher crystallinity (73%) than that of untreated fiber (33%), and possessed of good thermal stability which is suitable for nanocomposite material. Copyright © 2016 Elsevier Ltd. All rights reserved.

Metalorganic Chemical Vapor Deposition of Ruthenium-Doped Diamond like Carbon Films

NASA Technical Reports Server (NTRS)

Sunkara, M. K.; Ueno, M.; Lian, G.; Dickey, E. C.

2001-01-01

We investigated metalorganic precursor deposition using a Microwave Electron Cyclotron Resonance (ECR) plasma for depositing metal-doped diamondlike carbon films. Specifically, the deposition of ruthenium doped diamondlike carbon films was investigated using the decomposition of a novel ruthenium precursor, Bis(ethylcyclopentadienyl)-ruthenium (Ru(C5H4C2H5)2). The ruthenium precursor was introduced close to the substrate stage. The substrate was independently biased using an applied RF power. Films were characterized using Fourier Transform Infrared Spectroscopy (FTIR), Transmission Electron Microscopy (TEM) and Four Point Probe. The conductivity of the films deposited using ruthenium precursor showed strong dependency on the deposition parameters such as pressure. Ruthenium doped sample showed the presence of diamond crystallites with an average size of approx. 3 nm while un-doped diamondlike carbon sample showed the presence of diamond crystallites with an average size of 11 nm. TEM results showed that ruthenium was atomically dispersed within the amorphous carbon network in the films.

Glycyrrhetinic acid-functionalized mesoporous silica nanoparticles as hepatocellular carcinoma-targeted drug carrier.

PubMed

Lv, Yongjiu; Li, Jingjing; Chen, Huali; Bai, Yan; Zhang, Liangke

2017-01-01

In this study, a glycyrrhetinic acid-functionalized mesoporous silica nanoparticle (MSN-GA) was prepared for active tumor targeting. MSN-GA exhibited satisfactory loading capacity for insoluble drugs, uniform size distribution, and specific tumor cell targeting. Glycyrrhetinic acid, a hepatocellular carcinoma-targeting group, was covalently decorated on the surface of MSN via an amido bond. The successful synthesis of MSN-GA was validated by the results of Fourier transform infrared spectroscopy, transmission electron microscopy (TEM), and zeta potential measurement. TEM images revealed the spherical morphology and uniform size distribution of the naked MSN and MSN-GA. Curcumin (CUR), an insoluble model drug, was loaded into MSN-GA (denoted as MSN-GA-CUR) with a high-loading capacity (8.78%±1.24%). The results of the in vitro cellular experiment demonstrated that MSN-GA-CUR significantly enhanced cytotoxicity and cellular uptake toward hepatocellular carcinoma (HepG2) cells via a specific GA receptor-mediated endocytosis mechanism. The results of this study provide a promising nanoplatform for the targeting of hepatocellular carcinoma.

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.

Thermal stability and electrochemical properties of PVP-protected Ru nanoparticles synthesized at room temperature

NASA Astrophysics Data System (ADS)

Kumar, Manish; Devi, Pooja; Shivling, V. D.

2017-08-01

Stable ruthenium nanoparticles (RuNPs) have been synthesized by the chemical reduction of ruthenium trichloride trihydrate (RuCl3 · 3H2O) using sodium borohydride (NaBH4) as a reductant and polyvinylpyrrolidone (PVP) as a protecting agent in the aqueous medium at room temperature. The nanoparticles thus prepared were characterized by their morphology and structural analysis from transmission electron microscopy (TEM), X-ray powder diffraction (XRD), UV-vis spectroscopy, Fourier transformation infrared and thermogravimetric analysis (TGA) techniques. The TEM image suggested a homogeneous distribution of PVP-protected RuNPs having a small average diameter of 2-4 nm with a chain-like network structure. The XRD pattern also confirmed that a crystallite size is around 2 nm of PVP-protected RuNPs having a single broad peak. The thermal stability studied using TGA, indicated good stability and the electrochemical properties of these nanoparticles revealed that saturation current increases for PVP-protected RuNPs/GC.

Effects of multiple organic ligands on size uniformity and optical properties of ZnSe quantum dots

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

Archana, J., E-mail: archana.jayaram@yahoo.com; Navaneethan, M.; Hayakawa, Y.

2012-08-15

Highlights: ► Highly monodispersed ZnSe quantum dots have been synthesized by wet chemical route. ► Strong quantum confinement effect have been observed in ∼ 4 nm ZnSe quantum dots. ► Enhanced ultraviolet near band emission have been obtained using long chain polymer. -- Abstract: The effects of multi-ligands on the formation and optical transitions of ZnSe quantum dots have been investigated. The dots are synthesized using 3-mercapto-1,2-propanediol and polyvinylpyrrolidone ligands, and have been characterized by X-ray diffraction, transmission electron microscopy (TEM), UV–visible absorption spectroscopy, photoluminescence spectroscopy, and Fourier transform infrared spectroscopy. TEM reveals high monodispersion with an average size ofmore » 4 nm. Polymer-stabilized, organic ligand-passivated ZnSe quantum dots exhibit strong UV emission at 326 nm and strong quantum confinement in the UV–visible absorption spectrum. Uniform size and suppressed surface trap emission are observed when the polymer ligand is used. The possible growth mechanism is discussed.« less

Green Synthesis of Magnetite (Fe3O4) Nanoparticles Using Seaweed ( Kappaphycus alvarezii) Extract

NASA Astrophysics Data System (ADS)

Yew, Yen Pin; Shameli, Kamyar; Miyake, Mikio; Kuwano, Noriyuki; Bt Ahmad Khairudin, Nurul Bahiyah; Bt Mohamad, Shaza Eva; Lee, Kar Xin

2016-06-01

In this study, a simple, rapid, and eco-friendly green method was introduced to synthesize magnetite nanoparticles (Fe3O4-NPs) successfully. Seaweed Kappaphycus alvarezii ( K. alvarezii) was employed as a green reducing and stabilizing agents. The synthesized Fe3O4-NPs were characterized with X-ray diffraction (XRD), ultraviolet-visible spectroscopy (UV-Vis), Fourier transform infrared (FT-IR), and transmission electron microscopy (TEM) techniques. The X-ray diffraction planes at (220), (311), (400), (422), (511), (440), and (533) were corresponding to the standard Fe3O4 patterns, which showed the high purity and crystallinity of Fe3O4-NPs had been synthesized. Based on FT-IR analysis, two characteristic absorption peaks were observed at 556 and 423 cm-1, which proved the existence of Fe3O4 in the prepared nanoparticles. TEM image displayed the synthesized Fe3O4-NPs were mostly in spherical shape with an average size of 14.7 nm.

Green Synthesis of Magnetite (Fe3O4) Nanoparticles Using Seaweed (Kappaphycus alvarezii) Extract.

PubMed

Yew, Yen Pin; Shameli, Kamyar; Miyake, Mikio; Kuwano, Noriyuki; Bt Ahmad Khairudin, Nurul Bahiyah; Bt Mohamad, Shaza Eva; Lee, Kar Xin

2016-12-01

In this study, a simple, rapid, and eco-friendly green method was introduced to synthesize magnetite nanoparticles (Fe3O4-NPs) successfully. Seaweed Kappaphycus alvarezii (K. alvarezii) was employed as a green reducing and stabilizing agents. The synthesized Fe3O4-NPs were characterized with X-ray diffraction (XRD), ultraviolet-visible spectroscopy (UV-Vis), Fourier transform infrared (FT-IR), and transmission electron microscopy (TEM) techniques. The X-ray diffraction planes at (220), (311), (400), (422), (511), (440), and (533) were corresponding to the standard Fe3O4 patterns, which showed the high purity and crystallinity of Fe3O4-NPs had been synthesized. Based on FT-IR analysis, two characteristic absorption peaks were observed at 556 and 423 cm(-1), which proved the existence of Fe3O4 in the prepared nanoparticles. TEM image displayed the synthesized Fe3O4-NPs were mostly in spherical shape with an average size of 14.7 nm.

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

PubMed

Habibi, Neda

2014-10-15

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

Fabrication, characterization and application of pectin degrading Fe3O4-SiO2 nanobiocatalyst.

PubMed

Seenuvasan, Muthulingam; Malar, Carlin Geor; Preethi, Sridhar; Balaji, Nagarajan; Iyyappan, Jeyaraj; Kumar, Madhava Anil; Kumar, Kannaiyan Sathish

2013-05-01

The covalent binding of pectinase onto amino functionalized silica-coated magnetic nanoparticles (CSMNPs) through glutaraldehyde activation was investigated for nanobiocatalyst fabrication. The average particle size and morphology of the nanoparticles were characterized using transmission electron microscopy (TEM). The statistical analysis for TEM image suggests that the coating and binding process did not cause any significant change in size of MNPs. The morphological and phase change of the magnetic nanoparticles (MNPs) after various coatings and immobilization were characterized by X-ray diffraction (XRD) studies. The various surface modifications and pectinase binding onto nanoparticles were confirmed by Fourier transform infrared (FT-IR) spectroscopy. The maximum activity of immobilized pectinase was obtained at its weight ratio of 19.0×10(-3) mg bound pectinase/mg CSMNPs. The pH, temperature, reusability, storage ability and kinetic studies were established to monitor their improved stability and activity of the fabricated nanobiocatalyst. Furthermore, the application was extended in the clarification of Malus domestica juice. Copyright © 2013 Elsevier B.V. All rights reserved.

Green synthesis of gold nanoparticles using aqueous extract of Dillenia indica

NASA Astrophysics Data System (ADS)

Sett, Arghya; Gadewar, Manoj; Sharma, Pragya; Deka, Manab; Bora, Utpal

2016-06-01

In this study, we report a novel method of gold nanoparticle (AuNP) synthesis using aqueous fruit extract of Dillenia indica. The phytochemicals present in the fruit extract act as an effective reducing and capping agent to synthesize AuNPs. The synthesized AuNPs were characterized by spectrophotometry, transmission electron microscopy (TEM), x-ray diffraction (XRD), and Fourier transform infrared (FTIR) spectroscopy. TEM studies revealed the particles of various sizes and mainly spherical in shape. Selected-area electron diffraction (SAED) patterns and high-resolution transmission electron microscopy (HRTEM) images confirmed the crystallinity of the particles. The XRD patterns showed peaks at (111), (200), (220) which exhibited preferential orientation of the AuNPs as face-centered cubic crystal. FTIR measurements confirmed the coating of phenolic compounds on the AuNPs indicating a possible role of biomolecules for the capping and efficient stabilization of the AuNPs. The synthesized AuNPs did not show any form of cytotoxicity in the normal fibroblast cell line L929.

Electric current distribution of a multiwall carbon nanotube

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

Chen, Li-Ying; Chang, Chia-Seng, E-mail: jasonc@phys.sinica.edu.tw; Institute of Physics, Academia Sinica, Taipei 11529, Taiwan

2016-07-15

The electric current distribution in a multiwall carbon nanotube (MWCNT) was studied by in situ measuring the electric potential along an individual MWCNT in the ultra-high vacuum transmission electron microscope (TEM). The current induced voltage drop along each section of a side-bonded MWCNT was measured by a potentiometric probe in TEM. We have quantitatively derived that the current on the outermost shell depends on the applied current and the shell diameter. More proportion of the total electronic carriers hop into the inner shells when the applied current is increased. The larger a MWCNT’s diameter is, the easier the electronic carriersmore » can hop into the inner shells. We observed that, for an 8 nm MWCNT with 10 μA current applied, 99% of the total current was distributed on the outer two shells.« less

Imaging of subunit complexes of thermophilic bacterium H(+)-ATPase with scanning tunneling microscopy.

PubMed

Masai, J; Shibata, T; Kagawa, Y; Kondo, S

1992-07-01

Using a scanning tunneling microscope (STM), we observed reconstructed subunit complexes of H(+)-ATPase of a thermophilic bacterium. The measurement was carried out in air without conductive coating on the samples deposited on a highly oriented pyrolytic graphite (HOPG). The F1 subunit complex of the H(+)-ATPase, and an H(+)-ATPase whose F0 portion was embedded into liposomes prepared from soybean lecithin were imaged. Overall structural images of the subunit complex F1 were obtained: the structural dimensions of the STM images are in agreement with those deduced from conventional methods such as an transmission electron microscopy (TEM) and small-angle X-ray scattering (SAX) experimentation. Regarding the STM imaging of these samples, we discuss the advantages and disadvantages of the STM over those of conventional methods such as a TEM and SAX.

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

PubMed

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

2017-10-01

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

Revelation of graphene-Au for direct write deposition and characterization

NASA Astrophysics Data System (ADS)

Bhandari, Shweta; Deepa, Melepurath; Joshi, Amish G.; Saxena, Aditya P.; Srivastava, Avanish K.

2011-06-01

Graphene nanosheets were prepared using a modified Hummer's method, and Au-graphene nanocomposites were fabricated by in situ reduction of a gold salt. The as-produced graphene was characterized by X-ray photoelectron spectroscopy, ultraviolet-visible spectroscopy, scanning electron microscopy, and high-resolution transmission electron microscopy (HR-TEM). In particular, the HR-TEM demonstrated the layered crystallites of graphene with fringe spacing of about 0.32 nm in individual sheets and the ultrafine facetted structure of about 20 to 50 nm of Au particles in graphene composite. Scanning helium ion microscopy (HIM) technique was employed to demonstrate direct write deposition on graphene by lettering with gaps down to 7 nm within the chamber of the microscope. Bare graphene and graphene-gold nanocomposites were further characterized in terms of their composition and optical and electrical properties.

Defocus and magnification dependent variation of TEM image astigmatism.

PubMed

Yan, Rui; Li, Kunpeng; Jiang, Wen

2018-01-10

Daily alignment of the microscope is a prerequisite to reaching optimal lens conditions for high resolution imaging in cryo-EM. In this study, we have investigated how image astigmatism varies with the imaging conditions (e.g. defocus, magnification). We have found that the large change of defocus/magnification between visual correction of astigmatism and subsequent data collection tasks, or during data collection, will inevitably result in undesirable astigmatism in the final images. The dependence of astigmatism on the imaging conditions varies significantly from time to time, so that it cannot be reliably compensated by pre-calibration of the microscope. Based on these findings, we recommend that the same magnification and the median defocus of the intended defocus range for final data collection are used in the objective lens astigmatism correction task during microscope alignment and in the focus mode of the iterative low-dose imaging. It is also desirable to develop a fast, accurate method that can perform dynamic correction of the astigmatism for different intended defocuses during automated imaging. Our findings also suggest that the slope of astigmatism changes caused by varying defocuses can be used as a convenient measurement of objective lens rotation symmetry and potentially an acceptance test of new electron microscopes.

New Insights into CO2 Adsorption on Layered Double Hydroxide (LDH)-Based Nanomaterials

NASA Astrophysics Data System (ADS)

Tang, Nian; He, Tingyu; Liu, Jie; Li, Li; Shi, Han; Cen, Wanglai; Ye, Zhixiang

2018-02-01

The interlamellar spacing of layered double hydroxides (LDHs) was enlarged by dodecyl sulfonate ions firstly, and then, (3-aminopropyl)triethoxysilane (APS) was chemically grafted (APS/LDHs). The structural characteristics and thermal stability of these prepared samples were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), reflectance Fourier transform infrared spectrometer (FTIR), thermogravimetric analysis (TG), and elemental analysis (EA) respectively. The CO2 adsorption performance was investigated adopting TG and diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS). The results presented that the CO2 adsorption capacity on APS/LDHs was as high as 90 mg/g and showed no obvious reduction during a five cyclic adsorption-desorption test, indicating its superior performance stability. The DRIFTS results showed that both carbamates and weakly bounded CO2 species were generated on APS/LDHs. The weakly adsorbed species was due to the different local chemical environment for CO2 capture provided by the surface moieties of LDHs like free silanol and hydrogen bonds.

Tetraspanins and Transmembrane Adaptor Proteins As Plasma Membrane Organizers-Mast Cell Case.

PubMed

Halova, Ivana; Draber, Petr

2016-01-01

The plasma membrane contains diverse and specialized membrane domains, which include tetraspanin-enriched domains (TEMs) and transmembrane adaptor protein (TRAP)-enriched domains. Recent biophysical, microscopic, and functional studies indicated that TEMs and TRAP-enriched domains are involved in compartmentalization of physicochemical events of such important processes as immunoreceptor signal transduction and chemotaxis. Moreover, there is evidence of a cross-talk between TEMs and TRAP-enriched domains. In this review we discuss the presence and function of such domains and their crosstalk using mast cells as a model. The combined data based on analysis of selected mast cell-expressed tetraspanins [cluster of differentiation (CD)9, CD53, CD63, CD81, CD151)] or TRAPs [linker for activation of T cells (LAT), non-T cell activation linker (NTAL), and phosphoprotein associated with glycosphingolipid-enriched membrane microdomains (PAG)] using knockout mice or specific antibodies point to a diversity within these two families and bring evidence of the important roles of these molecules in signaling events. An example of this diversity is physical separation of two TRAPs, LAT and NTAL, which are in many aspects similar but show plasma membrane location in different microdomains in both non-activated and activated cells. Although our understanding of TEMs and TRAP-enriched domains is far from complete, pharmaceutical applications of the knowledge about these domains are under way.

High-definition Fourier transform infrared spectroscopic imaging of prostate tissue

NASA Astrophysics Data System (ADS)

Wrobel, Tomasz P.; Kwak, Jin Tae; Kadjacsy-Balla, Andre; Bhargava, Rohit

2016-03-01

Histopathology forms the gold standard for cancer diagnosis and therapy, and generally relies on manual examination of microscopic structural morphology within tissue. Fourier-Transform Infrared (FT-IR) imaging is an emerging vibrational spectroscopic imaging technique, especially in a High-Definition (HD) format, that provides the spatial specificity of microscopy at magnifications used in diagnostic surgical pathology. While it has been shown for standard imaging that IR absorption by tissue creates a strong signal where the spectrum at each pixel is a quantitative "fingerprint" of the molecular composition of the sample, here we show that this fingerprint also enables direct digital pathology without the need for stains or dyes for HD imaging. An assessment of the potential of HD imaging to improve diagnostic pathology accuracy is presented.

Correlative Fluorescence and Electron Microscopy in 3D-Scanning Electron Microscope Perspective.

PubMed

Franks, Jonathan; Wallace, Callen T; Shibata, Masateru; Suga, Mitsuo; Erdman, Natasha; Stolz, Donna B; Watkins, Simon C

2017-04-03

The ability to correlate fluorescence microscopy (FM) and electron microscopy (EM) data obtained on biological (cell and tissue) specimens is essential to bridge the resolution gap between the data obtained by these different imaging techniques. In the past such correlations were limited to either EM navigation in two dimensions to the locations previously highlighted by fluorescence markers, or subsequent high-resolution acquisition of tomographic information using a TEM. We present a novel approach whereby a sample previously investigated by FM is embedded and subjected to sequential mechanical polishing and backscatter imaging by scanning electron microscope. The resulting three dimensional EM tomogram of the sample can be directly correlated to the FM data. © 2017 by John Wiley & Sons, Inc. Copyright © 2017 John Wiley & Sons, Inc.

The temperature-dependency of the optical band gap of ZnO measured by electron energy-loss spectroscopy in a scanning transmission electron microscope

NASA Astrophysics Data System (ADS)

Granerød, Cecilie S.; Galeckas, Augustinas; Johansen, Klaus Magnus; Vines, Lasse; Prytz, Øystein

2018-04-01

The optical band gap of ZnO has been measured as a function of temperature using Electron Energy-Loss Spectroscopy (EELS) in a (Scanning) Transmission Electron Microscope ((S)TEM) from approximately 100 K up towards 1000 K. The band gap narrowing shows a close to linear dependency for temperatures above 250 K and is accurately described by Varshni, Bose-Einstein, Pässler and Manoogian-Woolley models. Additionally, the measured band gap is compared with both optical absorption measurements and photoluminescence data. STEM-EELS is here shown to be a viable technique to measure optical band gaps at elevated temperatures, with an available temperature range up to 1500 K and the benefit of superior spatial resolution.

Exfoliation of graphite into graphene in polar solvents mediated by amphiphilic hexa-peri-hexabenzocoronene.

PubMed

Kabe, Ryota; Feng, Xinliang; Adachi, Chihaya; Müllen, Klaus

2014-11-01

A water-soluble surfactant consisting of hexa-peri-hexabenzocoronene (HBC) as hydrophobic aromatic core and hydrophilic carboxy substituents was synthesized. It exhibited a self-assembled nanofiber structure in the solid state. Profiting from the π interactions between the large aromatic core of HBC and graphene, the surfactant mediated the exfoliation of graphite into graphene in polar solvents, which was further stabilized by the bulky hydrophilic carboxylic groups. A graphene dispersion with a concentration as high as 1.1 mg L(-1) containing 2-6 multilayer nanosheets was obtained. The lateral size of the graphene sheets was in the range of 100-500 nm based on atomic force microscope (AFM) and transmission electron microscope (TEM) measurements. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

High angular and spectral selectivity of purple emperor (Lepidoptera: Apatura iris and A. ilia) butterfly wings.

PubMed

Pantelić, Dejan; Curčić, Srećko; Savić-Šević, Svetlana; Korać, Aleksandra; Kovačević, Aleksander; Curčić, Božidar; Bokić, Bojana

2011-03-28

The iridescent features of the butterfly species Apatura iris (Linnaeus, 1758) and A. ilia (Denis & Schiffermüller, 1775) were studied. We recognized the structural color of scales only on the dorsal side of both the fore and hind wings of males of both of the aforementioned butterfly species. The scale dimensions and microstructure were analyzed by a scanning electron microscope (SEM) and transmission electron microscope (TEM). The optical properties were measured and it was found that the peak reflectivity is around 380 nm, with a spectral width (full width at half maximum) of approximately 50 nm in both species. The angular selectivity is high and a purple iridescent color is observed within the angular range of only 18 degrees in both species.

A simple tool for stereological assessment of digital images: the STEPanizer.

PubMed

Tschanz, S A; Burri, P H; Weibel, E R

2011-07-01

STEPanizer is an easy-to-use computer-based software tool for the stereological assessment of digitally captured images from all kinds of microscopical (LM, TEM, LSM) and macroscopical (radiology, tomography) imaging modalities. The program design focuses on providing the user a defined workflow adapted to most basic stereological tasks. The software is compact, that is user friendly without being bulky. STEPanizer comprises the creation of test systems, the appropriate display of digital images with superimposed test systems, a scaling facility, a counting module and an export function for the transfer of results to spreadsheet programs. Here we describe the major workflow of the tool illustrating the application on two examples from transmission electron microscopy and light microscopy, respectively. © 2011 The Authors Journal of Microscopy © 2011 Royal Microscopical Society.

Structural, magnetic and electronic structure properties of Co doped ZnO nanoparticles

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

Kumar, Shalendra, E-mail: shailuphy@gmail.com; School of Materials Science and Engineering, Changwon National University, Changwon, Gyeongnam 641-773; Song, T.K., E-mail: tksong@changwon.ac.kr

Highlights: • XRD and HR-TEM results show the single phase nature of Co doped ZnO nanoparticles. • XMCD and dc magnetization results indicate the RT-FM in Co doped ZnO nanoparticles. • Co L{sub 3,2} NEXAFS spectra infer that Co ions are in 2+ valence state. • O K edge NEXAFS spectra show that O vacancy increases with Co doping in ZnO. - Abstract: We reported structural, magnetic and electronic structure studies of Co doped ZnO nanoparticles. Doping of Co ions in ZnO host matrix has been studied and confirmed using various methods; such as X-ray diffraction (XRD), field emission scanningmore » electron microscopy (FE-SEM), energy dispersed X-ray (EDX), high resolution transmission electron microscopy (HR-TEM), Fourier transform infrared spectroscopy (FT-IR), near edge X-ray absorption fine structure (NEXAFS) spectroscopy, magnetic hysteresis loop measurements and X-ray magnetic circular dichroism (XMCD). From the XRD and HR-TEM results, it is observed that Co doped ZnO nanoparticles have single phase nature with wurtzite structure and exclude the possibility of secondary phase formation. FE-SEM and TEM micrographs show that pure and Co doped nanoparticles are nearly spherical in shape. O K edge NEXAFS spectra indicate that O vacancies increase with Co doping. The Co L{sub 3,2} edge NEXAFS spectra revealed that Co ions are in 2+ valence state. DC magnetization hysteresis loops and XMCD results clearly showed the intrinsic origin of temperature ferromagnetism in Co doped ZnO nanoparticles.« less

Ultrastructural characterization and Fourier analysis of fiber cell cytoplasm in the hyperbaric oxygen treated guinea pig lens opacification model.

PubMed

Freel, Christopher D; Gilliland, Kurt O; Mekeel, Harold E; Giblin, Frank J; Costello, M Joseph

2003-04-01

The structural characteristics of differentiated fiber cells in control and hyperbaric oxygen (HBO)-treated guinea pig lenses were examined by transmission electron microscopy (TEM). Emphasis was placed on cell damage, membrane integrity, and cytoplasmic texture. Given the faint gross opacities observed in HBO-treated lenses in previous studies, it was hypothesized that subtle but significant morphological differences due to oxidative damage exist between control and treated animals. Experimental animals received either 70 or 85 treatments with HBO (2.5 atm of 100% O(2) for 2.5 hr, 3 times per week for 5-7 months). All specimens were obtained within 24 hr of death. Freshly cut Vibratome lens sections were fixed and processed for low and high-magnification thin-section TEM analysis. Cytoplasmic texture was analyzed using Fourier and autocorrelation image processing techniques. Low-magnification analysis revealed relatively insignificant differences in general appearance between the fiber cells of the inner fetal and embryonic nuclei in control and HBO-treated guinea pigs. Both groups demonstrated cells of similar morphology with equivalent membrane complexity and homogeneous cytoplasmic texture. Evidence of any major cellular damage or extracellular space debris was not obvious. High-magnification analysis of the cytoplasm of the treated lenses exhibited a mild, yet detectable increase in texture compared with controls and was confirmed by Fourier analysis. Cytoplasmic texture increased in complexity with additional treatments. The absence of major cellular damage in the lenses of HBO-treated animals suggests a less conspicuous source of light scattering. The small changes in cytoplasmic organization observed between treated and control animals may entirely account for the increase in nuclear light scattering observed by slit lamp. The results obtained with this guinea pig/HBO model parallel many of the morphological data associated with human nuclear cataracts. The high-angle scattering observed in the lens of the HBO-treated guinea pig may represent the type of cytoplasmic reorganization that occurs with mild oxidation, effectively making it a valuable model for human lens aging.

Synthesis and characterization of graphene quantum dots/cobalt ferrite nanocomposite

NASA Astrophysics Data System (ADS)

Ramachandran, Shilpa; Sathishkumar, M.; Kothurkar, Nikhil K.; Senthilkumar, R.

2018-02-01

A facile method has been developed for the synthesis of a graphene quantum dots/cobalt ferrite nanocomposite. Graphene quantum dots (GQDs) were synthesized by a simple bottom-up method using citric acid, followed by the co-precipitation of cobalt ferrite nanoparticles on the graphene quantum dots. The morphology, structural analysis, optical properties, magnetic properties were investigated using transmission electron microscopy (TEM), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), UV-vis absorption spectroscopy, fluorescence spectroscopy, vibrating sample magnetometry (VSM) measurements. The synthesized nanocomposite showed good fluorescence and superparamagnetic properties, which are important for biomedical applications.

Hydrothermal Synthesis and Biocompatibility Study of Highly Crystalline Carbonated Hydroxyapatite Nanorods

NASA Astrophysics Data System (ADS)

Xue, Caibao; Chen, Yingzhi; Huang, Yongzhuo; Zhu, Peizhi

2015-08-01

Highly crystalline carbonated hydroxyapatite (CHA) nanorods with different carbonate contents were synthesized by a novel hydrothermal method. The crystallinity and chemical structure of synthesized nanorods were studied by Fourier transform infrared spectroscopy (FTIR), X-ray photo-electronic spectroscopy (XPS), X-ray diffraction (XRD), Raman spectroscopy, and transmission electron microscopy (TEM). The biocompatibility of synthesized CHA nanorods was evaluated by cell viability and alkaline phosphatase (ALP) activity of MG-63 cell line. The biocompatibility evaluation results show that these CHA nanorods are biologically active apatites and potentially promising bone-substitute biomaterials for orthopedic application.

Wave field restoration using three-dimensional Fourier filtering method.

PubMed

Kawasaki, T; Takai, Y; Ikuta, T; Shimizu, R

2001-11-01

A wave field restoration method in transmission electron microscopy (TEM) was mathematically derived based on a three-dimensional (3D) image formation theory. Wave field restoration using this method together with spherical aberration correction was experimentally confirmed in through-focus images of amorphous tungsten thin film, and the resolution of the reconstructed phase image was successfully improved from the Scherzer resolution limit to the information limit. In an application of this method to a crystalline sample, the surface structure of Au(110) was observed in a profile-imaging mode. The processed phase image showed quantitatively the atomic relaxation of the topmost layer.

Manipulator for rotating and translating a sample holder

DOEpatents

van de Water, Jeroen [Breugel, NL; van den Oetelaar, Johannes [Eindhoven, NL; Wagner, Raymond [Gorinchem, NL; Slingerland, Hendrik Nicolaas [Venlo, NL; Bruggers, Jan Willem [Eindhoven, NL; Ottevanger, Adriaan Huibert Dirk [Malden, NL; Schmid, Andreas [Berkeley, CA; Olson, Eric A [Champaign, IL; Petrov, Ivan G [Champaign, IL; Donchev, Todor I [Urbana, IL; Duden, Thomas [Kensington, CA

2011-02-08

A manipulator for use in e.g. a Transmission Electron Microscope (TEM) is described, said manipulator capable of rotating and translating a sample holder (4). The manipulator clasps the round sample holder between two members (3A, 3B), said members mounted on actuators (2A, 2B). Moving the actuators in the same direction results in a translation of the sample holder, while moving the actuators in opposite directions results in a rotation of the sample holder.

Proceedings of International Wire and Cable Symposium (24th), Held at Cherry Hill, New Jersey, on November 18, 19 and 20, 1975

DTIC Science & Technology

1975-11-01

by acceptors such as hydrogen ion (H+) to form hydrogen gas. These microscopic batter- ies on the surface of a corroding metal are called local...session on Effects of EMP on Cable Sys- tems. Mr. I. Kolodny, General Cable, was Chairman of the session. Awards were presented by the symposium co... the conductor and on the outside of the insulation and these measurements were

The dynamic response and shock-recovery of porcine skeletal muscle tissue

NASA Astrophysics Data System (ADS)

Wilgeroth, James Michael; Hazell, Paul; Appleby-Thomas, Gareth James

2012-03-01

A soft-capture system allowing for one-dimensional shock loading and release of soft tissues via the plate-impact technique has been developed. In addition, we present the numerical simulation of a shock-recovery experiment involving porcine skeletal muscle and further investigate the effects of the transient wave on the structure of the tissue via transmission electron microscope (TEM). This paper forms part of an ongoing research programme on the dynamic behaviour of skeletal muscle tissue.

Irradiation-induced creep in metallic nanolaminates characterized by In situ TEM pillar nanocompression

DOE PAGES

Dillon, Shen J.; Bufford, Daniel C.; Jawaharram, Gowtham S.; ...

2017-04-13

Our work reports on irradiation-induced creep (IIC) measured on nanolaminate (Cu-W and Ni-Ag) and nanocrystalline alloys (Cu-W) at room temperature using a combination of heavy ion irradiation and nanopillar compression performed concurrently in situ in a transmission electron microscope. Furthermore, we observed appreciable IIC in multilayers with 50 nm layer thicknesses at high stress, ≈½ the yield strength, but not in multilayers with only 5 nm layer thicknesses.

A facile approach to prepare porous cup-stacked carbon nanotube with high performance in adsorption of methylene blue.

PubMed

Gong, Jiang; Liu, Jie; Jiang, Zhiwei; Wen, Xin; Mijowska, Ewa; Tang, Tao; Chen, Xuecheng

2015-05-01

Novel porous cup-stacked carbon nanotube (P-CSCNT) with special stacked morphology consisting of many truncated conical graphene layers was synthesized by KOH activating CSCNT from polypropylene. The morphology, microstructure, textural property, phase structure, surface element composition and thermal stability of P-CSCNT were investigated by field-emission scanning electron microscope, transmission electron microscope (TEM), high-resolution TEM, N2 sorption, X-ray diffraction, Raman spectroscopy, X-ray photoelectron spectroscopy and thermal gravimetric analysis. A part of oblique graphitic layers were etched by KOH, and many holes with a diameter of several to a doze of nanometers connecting inner tube with outside were formed, which endowed P-CSCNT with high specific surface area (558.7 m(2)/g), large pore volume (1.993 cm(3)/g) and abundant surface functional groups. Subsequently, P-CSCNT was used for adsorption of methylene blue (MB) from wastewater. Langmuir model closely fitted the adsorption results, and the maximum adsorption capacity of P-CSCNT was as high as 319.1mg/g. This was ascribed to multiple adsorption mechanisms including pore filling, hydrogen bonding, π-π and electrostatic interactions. Pseudo second-order kinetic model was more valid to describe the adsorption behavior. Besides, P-CSCNT showed good recyclablity and reusability. These results demonstrated that P-CSCNT had potential application in wastewater treatment. Copyright © 2015 Elsevier Inc. All rights reserved.

ATP-containing vesicles in stria vascular marginal cell cytoplasms in neonatal rat cochlea are lysosomes.

PubMed

Liu, Jun; Liu, Wenjing; Yang, Jun

2016-02-11

We confirmed that ATP is released from cochlear marginal cells in the stria vascular but the cell organelle in which ATP stores was not identified until now. Thus, we studied the ATP-containing cell organelles and suggest that these are lysosomes. Primary cultures of marginal cells of Sprague-Dawley rats aged 1-3 days was established. Vesicles within marginal cells stained with markers were identified under confocal laser scanning microscope and transmission electron microscope (TEM). Then ATP release from marginal cells was measured after glycyl-L-phenylalanine-ß- naphthylamide (GPN) treatment using a bioluminescent assay. Quinacrine-stained granules within marginal cells were labeled with LysoTracker, a lysosome tracer, and lysosomal-associated membrane protein 1(LAMP1), but not labeled with the mitochondrial tracer MitoTracker. Furthermore, LysoTracker-labelled puncta showed accumulation of Mant-ATP, an ATP analog. Treatment with 200 μM GPN quenched fluorescently labeled puncta after incubation with LysoTracker or quinacrine, but not MitoTracker. Quinacrine-labeled organelles observed by TEM were lysosomes, and an average 27.7 percent increase in ATP luminescence was observed in marginal cells extracellular fluid after GPN treatment. ATP-containing vesicles in cochlear marginal cells of the stria vascular from neonatal rats are likely lysosomes. ATP release from marginal cells may be via Ca(2+)-dependent lysosomal exocytosis.

Three-dimensional imaging of adherent cells using FIB/SEM and STEM.

PubMed

Villinger, Clarissa; Schauflinger, Martin; Gregorius, Heiko; Kranz, Christine; Höhn, Katharina; Nafeey, Soufi; Walther, Paul

2014-01-01

In this chapter we describe three different approaches for three-dimensional imaging of electron microscopic samples: serial sectioning transmission electron microscopy (TEM), scanning transmission electron microscopy (STEM) tomography, and focused ion beam/scanning electron microscopy (FIB/SEM) tomography. With these methods, relatively large volumes of resin-embedded biological structures can be analyzed at resolutions of a few nm within a reasonable expenditure of time. The traditional method is serial sectioning and imaging the same area in all sections. Another method is TEM tomography that involves tilting a section in the electron beam and then reconstruction of the volume by back projection of the images. When the scanning transmission (STEM) mode is used, thicker sections (up to 1 μm) can be analyzed. The third approach presented here is focused ion beam/scanning electron microscopy (FIB/SEM) tomography, in which a sample is repeatedly milled with a focused ion beam (FIB) and each newly produced block face is imaged with the scanning electron microscope (SEM). This process can be repeated ad libitum in arbitrary small increments allowing 3D analysis of relatively large volumes such as eukaryotic cells. We show that resolution of this approach is considerably improved when the secondary electron signal is used. However, the most important prerequisite for three-dimensional imaging is good specimen preparation. For all three imaging methods, cryo-fixed (high-pressure frozen) and freeze-substituted samples have been used.

Fabrication of Mesoporous Silica/Alumina Hybrid Membrane Film Nanocomposites using Template Sol-Gel Synthesis of Amphiphilic Triphenylene

NASA Astrophysics Data System (ADS)

Lintang, H. O.; Jalani, M. A.; Yuliati, L.; Salleh, M. M.

2017-05-01

Herein we reported that by introducing a one-dimensional (1D) substrate with a porous structure such as anodic aluminum oxide (AAO) membrane, mesoporous silica/alumina hybrid nanocomposites were successfully fabricated by using amphiphilic triphenylene (TPC10TEG) as a template in sol-gel synthesis (TPC10TEG/silicahex). For the optical study of the nanocomposites, TPC10TEG/silicahex showed absorption peak at 264 nm due to the ordered and long-range π-π stacking of the disc-like aromatic triphenylene core. Moreover, the hexagonal arrangement of TPC10TEG/silicahex was proven based on their diffraction peaks of d 100 and d 200 at 2θ = 2.52° and 5.04° and images of transmission electron microscopy (TEM), respectively. For fabrication of mesoporous silica/alumina hybrid membrane, TPC10TEG/silicahex was drop-casted onto AAO membrane for penetration into the porous structure via gravity. X-ray diffraction (XRD) analysis on the resulted hybrid nanocomposites showed that the diffraction peaks of d 100 and d 200 of TPC10TEG/silicahex were still preserved, indicating that the hexagonal arrangements of mesoporous silica were maintained even on AAO substrate. The morphology study on the hybrid nanocomposites using TEM, scanning electron microscope (SEM) and field emission scanning electron microscope (FE-SEM) showed the successful filling of most AAO channels with the TPC10TEG/silicahex nanocomposites.