Morphology selection for cupric oxide thin films by electrodeposition.

PubMed

Dhanasekaran, V; Mahalingam, T; Chandramohan, R

2011-10-01

Polycrystalline cupric oxide thin films were deposited using alkaline solution bath employing cathodic electrodeposition method. The thin films were electrodeposited at various solution pH. The surface morphology and elemental analyzes of the films were studied using scanning electron microscopy (SEM) and energy dispersive X-ray analysis, respectively. SEM studies revealed that the surface morphology could be tailored suitably by adjusting the pH value during deposition. Mesh average on multiple lattice mode atomic force microscopy image was obtained and reported. Copyright © 2011 Wiley-Liss, Inc.

The variation in surface morphology and hardness of human deciduous teeth samples after laser irradiation

NASA Astrophysics Data System (ADS)

Khalid, Arooj; Bashir, Shazia; Akram, Mahreen; Salman Ahmed, Qazi

2017-11-01

The variation in surface morphology and hardness of human deciduous teeth samples has been investigated after laser irradiation at different wavelengths and energies. Nd:YAG was employed as a source of irradiation for IR (1064 nm) and visible (532 nm) radiation, whereas an excimer laser was used as the source of UV (248 nm) radiation. Scanning electron microscope (SEM) analysis was carried out to reveal the surface morphological evolution of teeth samples. Vickers microhardness tester was employed to investigate the modifications in the hardness of the laser-treated samples. It is observed from SEM analysis that IR wavelength is responsible for ablation of collagen matrix and intertubular dentine. For visible radiation, the ablation of collagen along with hydroxypatite is observed. With UV radiation, the ablation of peritubular dentine is dominant and is responsible for the sealing of tubules. The decrease in hardness at lower energy for both wavelengths is due to the evaporation of carbon content. With increasing energy, evaporation of water along with carbon content, and resolidification and re-organization of inorganic content causes the increase in hardness of the treated dentine. SEM as well as microhardness analyses reveal that laser wavelengths and energy of laser radiation significantly influence the surface morphology and hardness of samples.

Automated Transmission-Mode Scanning Electron Microscopy (tSEM) for Large Volume Analysis at Nanoscale Resolution

PubMed Central

Kuwajima, Masaaki; Mendenhall, John M.; Lindsey, Laurence F.; Harris, Kristen M.

2013-01-01

Transmission-mode scanning electron microscopy (tSEM) on a field emission SEM platform was developed for efficient and cost-effective imaging of circuit-scale volumes from brain at nanoscale resolution. Image area was maximized while optimizing the resolution and dynamic range necessary for discriminating key subcellular structures, such as small axonal, dendritic and glial processes, synapses, smooth endoplasmic reticulum, vesicles, microtubules, polyribosomes, and endosomes which are critical for neuronal function. Individual image fields from the tSEM system were up to 4,295 µm2 (65.54 µm per side) at 2 nm pixel size, contrasting with image fields from a modern transmission electron microscope (TEM) system, which were only 66.59 µm2 (8.160 µm per side) at the same pixel size. The tSEM produced outstanding images and had reduced distortion and drift relative to TEM. Automated stage and scan control in tSEM easily provided unattended serial section imaging and montaging. Lens and scan properties on both TEM and SEM platforms revealed no significant nonlinear distortions within a central field of ∼100 µm2 and produced near-perfect image registration across serial sections using the computational elastic alignment tool in Fiji/TrakEM2 software, and reliable geometric measurements from RECONSTRUCT™ or Fiji/TrakEM2 software. Axial resolution limits the analysis of small structures contained within a section (∼45 nm). Since this new tSEM is non-destructive, objects within a section can be explored at finer axial resolution in TEM tomography with current methods. Future development of tSEM tomography promises thinner axial resolution producing nearly isotropic voxels and should provide within-section analyses of structures without changing platforms. Brain was the test system given our interest in synaptic connectivity and plasticity; however, the new tSEM system is readily applicable to other biological systems. PMID:23555711

Morphology and chemical composition of dentin in permanent first molars with the diagnose MIH.

PubMed

Heijs, Suzanne C B; Dietz, Wolfram; Norén, Jörgen G; Blanksma, Nynke G; Jälevik, Birgitta

2007-01-01

The purpose of this investigation was to study the morphology and distribution of some inorganic elements in dentin in first permanent molars from children with Molar-Incisor Hypomineralization (MIH). Sixty four tooth sections from thirty two children were examined in polarized light. Fifteen representative sections were selected for SEM/XRMA analysis; 5 were used for SEM analysis and 10 for XRMA analysis. No morphological changes in the dentin were revealed in polarized light microscopy (PLM). However, in all but two sections interglobular dentin was found. The SEM analyzes confirmed the findings of the PLM with no structural changes to be found in the dentin. The XRMA results showed a difference in the concentration of elements between dentin below normal and dentin below carious or hypomineralized enamel. Elements related to organic matter appeared with higher values in dentin below hypomineralized and carious enamel. The morphological and chemical findings in dentin below hypomineralized enamel imply that the odontoblasts are not affected in cases of MIH, but may be affected by hypocalcemia, reflected by the presence of interglobular dentin.

CdS thin films prepared by continuous wave Nd:YAG laser

NASA Astrophysics Data System (ADS)

Wang, H.; Tenpas, Eric W.; Vuong, Khanh D.; Williams, James A.; Schuesselbauer, E.; Bernstein, R.; Fagan, J. G.; Wang, Xing W.

1995-08-01

We report new results on continuous wave Nd:YAG laser deposition of cadmium sulfide thin films. Substrates were soda-lime silicate glass, silica glass, silicon, and copper coated formvar sheets. As deposited films were mixtures of cubic and hexagonal phases, with two different grain sizes. As revealed by SEM micrographs, films had smooth surface morphology. As revealed by TEM analysis, grain sizes were extremely small.

Investigation of Structure and Property of Indian Cocos nucifera L. Fibre

NASA Astrophysics Data System (ADS)

Basu, Gautam; Mishra, Leena; Samanta, Ashis Kumar

2017-12-01

Structure and physico-mechanical properties of Cocos nucifera L. fibre from a specific agro-climatic region of India, was thoroughly studied. Fine structure of the fibre was examined by Fourier Transform Infra-Red (FTIR) spectroscopy, Thermo-Gravimetric Analysis (TGA), X-Ray Diffraction (XRD), component analysis, Scanning Electron Microscope (SEM) and optical microscope. SEM shows prominent longitudinal cracks and micro-pores on the surface. XRD shows a low degree of crystallinity (45%), bigger crystallite size, and even the presence of appreciable amount of non-cellulose matter. FTIR reveals presence of large quantities of hydroxyl, phenolic and aldehyde groups. Component and thermal analyses indicates presence of cellulose and lignin as major components. Physical parameters reveal that, fibres are highly variable in length (range 44-305 mm), and diameter (range 100-795 µm). Mechanical properties of the fibre viz. breaking tenacity, breaking extensibility, specific work of rupture, and coefficient of friction were measured. Microbial decomposition test under soil reveals excellent durability of coconut fibre which makes it appropriate for the application in geotextiles. Mass specific electrical resistance of 4 Ω-kg/m2 indicates its enhanced insulation as compared to the jute.

Characterization of microorganisms isolated from the black dirt of toilet bowls and componential analysis of the black dirt.

PubMed

Mori, Miho; Nagata, Yusuke; Niizeki, Kazuma; Gomi, Mitsuhiro; Sakagami, Yoshikazu

2014-01-01

We have previously conducted a microflora analysis and examined the biofilm-forming activity of bacteria isolated from toilet bowl biofilms. In the present investigation, to reveal the strain involved in the formation of black dirt in toilet bowls, we performed a microflora analysis of the bacteria and fungi isolated from the black dirt of toilet bowls at ten homes. Among samples from different isolation sites and sampling seasons, although a similar tendency was not seen in bacterial microflora, Exophiala sp. was detected in the fungal microflora from all samples of black dirt except for one, and constituted the major presence. By scanning electron microscope (SEM) analysis of the formed black dirt, SEM image at × 1,000 and × 5,000 magnification showed objects like hyphae and many bacteria adhering to them, respectively. Micro fourier transform infrared spectroscopy (micro FT-IR) and SEM with X-ray microanalysis (SEM-XMA) were used to investigate the components of black dirt. IR spectra of micro-FT-IR showed typical absorptions associated with amide compounds and protein, and the elements such as C, N, O, Na, Mg, Al, Si, P, S, K, and Ba were detected with SEM-XMA. These results showed that black dirt had living body ingredients. Furthermore, Exophiala sp. and Cladosporium sp. strains, which were observed at a high frequency, accumulated 2-hydroxyjuglone (2-HJ) and flaviolin as one of the intermediates in the melanin biosynthetic pathway by the addition of a melanin synthesis inhibitor (tricyclazole) at the time of cultivation. These results suggested strongly that the pigment of black dirt in toilet bowls was melanin produced by Exophiala sp. and Cladosporium sp. strains.

Predictors of Satisfaction in Geographically Close and Long-Distance Relationships

ERIC Educational Resources Information Center

Lee, Ji-yeon; Pistole, M. Carole

2012-01-01

In this study, the authors examined geographically close (GCRs) and long-distance (LDRs) romantic relationship satisfaction as explained by insecure attachment, self-disclosure, gossip, and idealization. After college student participants (N = 536) completed a Web survey, structural equation modeling (SEM) multigroup analysis revealed that the GCR…

Biocompatibility evaluation of cigarette and carbon papers used in repair of traumatic tympanic membrane perforations: experimental study.

PubMed

Altuntaş, Emine Elif; Sümer, Zeynep

2013-01-01

The purposes of this study were to investigate the biocompatibility of two different paper patches (carbon and cigarette papers) and compare the adhesion and proliferation features of L929 fibroblast cells by using 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide (MTT Test) test and scanning electron microscopy (SEM). In this study, time-dependent cytotoxic effects of cigarette and carbon papers used in repairing small traumatic TM perforations were investigated in vitro by using MTT test. And also adhesion and spreading of cells over disk surface were observed by SEM. Cytotoxicity test carried out by MTT analysis on leakage products collected from two types of paper patches at the end of 24 and 48 h revealed no cytotoxicity (P > 0.05). In SEM studies, it was observed that cells started to proliferate over disk surface as a result of 48-h incubation, and SEM revealed that the cell proliferation over cigarette paper was more compared to the one over carbon paper. We believe that this is the first study where biocompatibility and adhesion features of carbon and cigarette paper have been studied by using L929 fibroblast cell culture. As a result, biocompatibility of cigarette paper and also whether cigarette paper was superior to carbon paper in cell attachment and biocompatibility were studied. It was found, by MTT test and SEM test, that cigarette paper had a higher biocompatibility and cell attachment, and thus cigarette paper should be the patch to be preferred in cases where TM perforations are repaired by paper-patch method.

Detailed methodology for high resolution scanning electron microscopy (SEM) of murine malaria parasitized-erythrocytes.

PubMed

Hayakawa, Eri H; Matsuoka, Hiroyuki

2016-10-01

Scanning electron microscopy (SEM) is a powerful tool used to investigate object surfaces and has been widely applied in both material science and biology. With respect to the study of malaria, SEM revealed that erythrocytes infected with Plasmodium falciparum, a human parasite, display 'knob-like' structures on their surface comprising parasitized proteins. However, detailed methodology for SEM studies of malaria parasites is lacking in the literature making such studies challenging. Here, we provide a step-by-step guide to preparing Plasmodium-infected erythrocytes from two mouse strains for SEM analysis with minimal structural deterioration. We tested three species of murine malaria parasites, P. berghei, P. yoelii, and P. chabaudi, as well as non-parasitized human erythrocytes and P. falciparum-infected erythrocytes for comparisons. Our data demonstrated that the surface structures of parasitized erythrocytes between the three species of murine parasites in the two different strains of mice were indistinguishable and no surface alterations were observed in P. falciparum-erythrocytes. Our SEM observations contribute towards an understanding of the molecular mechanisms of parasite maturation in the erythrocyte cytoplasm and, along with future studies using our detailed methodology, may help to gain insight into the clinical phenomena of human malaria. Copyright © 2016 The Authors. Published by Elsevier Ireland Ltd.. All rights reserved.

Structural analysis of zeolite NaA synthesized by a cost-effective hydrothermal method using kaolin and its use as water softener.

PubMed

Loiola, A R; Andrade, J C R A; Sasaki, J M; da Silva, L R D

2012-02-01

Zeolite 4A (LTA) has been successfully synthesized by a hydrothermal method, where kaolin was used as silica and alumina source. The synthesized zeolite was characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), laser granulometry, and FTIR spectroscopy. XRD data from the Rietveld refinement method confirmed only one crystallographic phase. Zeolite A morphology was observed by SEM analysis, and it showed well-defined crystals with slightly different sizes but with the same cubic shape. Particle size distribution of the crystals was confirmed by laser granulometry, whereas FTIR spectroscopy revealed significant structural differences between the starting material and the final zeolite product used as water softener. Copyright © 2010 Elsevier Inc. All rights reserved.

Modeling of Individual and Organizational Factors Affecting Traumatic Occupational Injuries Based on the Structural Equation Modeling: A Case Study in Large Construction Industries.

PubMed

Mohammadfam, Iraj; Soltanzadeh, Ahmad; Moghimbeigi, Abbas; Akbarzadeh, Mehdi

2016-09-01

Individual and organizational factors are the factors influencing traumatic occupational injuries. The aim of the present study was the short path analysis of the severity of occupational injuries based on individual and organizational factors. The present cross-sectional analytical study was implemented on traumatic occupational injuries within a ten-year timeframe in 13 large Iranian construction industries. Modeling and data analysis were done using the structural equation modeling (SEM) approach and the IBM SPSS AMOS statistical software version 22.0, respectively. The mean age and working experience of the injured workers were 28.03 ± 5.33 and 4.53 ± 3.82 years, respectively. The portions of construction and installation activities of traumatic occupational injuries were 64.4% and 18.1%, respectively. The SEM findings showed that the individual, organizational and accident type factors significantly were considered as effective factors on occupational injuries' severity (P < 0.05). Path analysis of occupational injuries based on the SEM reveals that individual and organizational factors and their indicator variables are very influential on the severity of traumatic occupational injuries. So, these should be considered to reduce occupational accidents' severity in large construction industries.

Scanning Electron Microscope-Cathodoluminescence Analysis of Rare-Earth Elements in Magnets.

PubMed

Imashuku, Susumu; Wagatsuma, Kazuaki; Kawai, Jun

2016-02-01

Scanning electron microscope-cathodoluminescence (SEM-CL) analysis was performed for neodymium-iron-boron (NdFeB) and samarium-cobalt (Sm-Co) magnets to analyze the rare-earth elements present in the magnets. We examined the advantages of SEM-CL analysis over conventional analytical methods such as SEM-energy-dispersive X-ray (EDX) spectroscopy and SEM-wavelength-dispersive X-ray (WDX) spectroscopy for elemental analysis of rare-earth elements in NdFeB magnets. Luminescence spectra of chloride compounds of elements in the magnets were measured by the SEM-CL method. Chloride compounds were obtained by the dropwise addition of hydrochloric acid on the magnets followed by drying in vacuum. Neodymium, praseodymium, terbium, and dysprosium were separately detected in the NdFeB magnets, and samarium was detected in the Sm-Co magnet by the SEM-CL method. In contrast, it was difficult to distinguish terbium and dysprosium in the NdFeB magnet with a dysprosium concentration of 1.05 wt% by conventional SEM-EDX analysis. Terbium with a concentration of 0.02 wt% in an NdFeB magnet was detected by SEM-CL analysis, but not by conventional SEM-WDX analysis. SEM-CL analysis is advantageous over conventional SEM-EDX and SEM-WDX analyses for detecting trace rare-earth elements in NdFeB magnets, particularly dysprosium and terbium.

Microscopy based studies on the interaction of bio-based silver nanoparticles with Bombyx mori Nuclear Polyhedrosis virus.

PubMed

Tamilselvan, Selvaraj; Ashokkumar, Thirunavukkarasu; Govindaraju, Kasivelu

2017-04-01

In the present investigation, silver nanoparticles (AgNPs) interactions with Bombyx mori Nuclear Polyhedrosis virus (BmNPV) were characterized using High-Resolution Scanning Electron Microscopy (HR-SEM), Energy Dispersive X-ray Analysis (EDAX), Transmission Electron Microscopy (TEM), Atomic Force Microcopy (AFM) and Confocal Microscope (CM). HR-SEM study reveals that the biosynthesized AgNPs have interacted with BmNPV and were found on the surface. TEM micrographs of normal and viral polyhedra treated with AgNPs showed that the nanoparticles were accumulated in the membrane and it was noted that some of the AgNPs successfully penetrated the membrane by reaching the capsid of BmNPV. AFM and confocal microscopy studies reveal that the disruption in the shell membrane tends to lose its stability due to exposure of AgNPs to BmNPV. Copyright © 2017 Elsevier B.V. All rights reserved.

Reliability and validity of CODA motion analysis system for measuring cervical range of motion in patients with cervical spondylosis and anterior cervical fusion.

PubMed

Gao, Zhongyang; Song, Hui; Ren, Fenggang; Li, Yuhuan; Wang, Dong; He, Xijing

2017-12-01

The aim of the present study was to evaluate the reliability of the Cartesian Optoelectronic Dynamic Anthropometer (CODA) motion system in measuring the cervical range of motion (ROM) and verify the construct validity of the CODA motion system. A total of 26 patients with cervical spondylosis and 22 patients with anterior cervical fusion were enrolled and the CODA motion analysis system was used to measure the three-dimensional cervical ROM. Intra- and inter-rater reliability was assessed by interclass correlation coefficients (ICCs), standard error of measurement (SEm), Limits of Agreements (LOA) and minimal detectable change (MDC). Independent samples t-tests were performed to examine the differences of cervical ROM between cervical spondylosis and anterior cervical fusion patients. The results revealed that in the cervical spondylosis group, the reliability was almost perfect (intra-rater reliability: ICC, 0.87-0.95; LOA, -12.86-13.70; SEm, 2.97-4.58; inter-rater reliability: ICC, 0.84-0.95; LOA, -13.09-13.48; SEm, 3.13-4.32). In the anterior cervical fusion group, the reliability was high (intra-rater reliability: ICC, 0.88-0.97; LOA, -10.65-11.08; SEm, 2.10-3.77; inter-rater reliability: ICC, 0.86-0.96; LOA, -10.91-13.66; SEm, 2.20-4.45). The cervical ROM in the cervical spondylosis group was significantly higher than that in the anterior cervical fusion group in all directions except for left rotation. In conclusion, the CODA motion analysis system is highly reliable in measuring cervical ROM and the construct validity was verified, as the system was sufficiently sensitive to distinguish between the cervical spondylosis and anterior cervical fusion groups based on their ROM.

A comparative study of heterostructured CuO/CuWO4 nanowires and thin films

NASA Astrophysics Data System (ADS)

Polyakov, Boris; Kuzmin, Alexei; Vlassov, Sergei; Butanovs, Edgars; Zideluns, Janis; Butikova, Jelena; Kalendarev, Robert; Zubkins, Martins

2017-12-01

A comparative study of heterostructured CuO/CuWO4 core/shell nanowires and double-layer thin films was performed through X-ray diffraction, confocal micro-Raman spectroscopy and electron (SEM and TEM) microscopies. The heterostructures were produced using a two-step process, starting from a deposition of amorphous WO3 layer on top of CuO nanowires and thin films by reactive DC magnetron sputtering and followed by annealing at 650 °C in air. The second step induced a solid-state reaction between CuO and WO3 oxides through a thermal diffusion process, revealed by SEM-EDX analysis. Morphology evolution of core/shell nanowires and double-layer thin films upon heating was studied by electron (SEM and TEM) microscopies. A formation of CuWO4 phase was confirmed by X-ray diffraction and confocal micro-Raman spectroscopy.

SEM/EDS and optical microscopy analyses of microplastics in ocean trawl and fish guts.

PubMed

Wang, Zhong-Min; Wagner, Jeff; Ghosal, Sutapa; Bedi, Gagandeep; Wall, Stephen

2017-12-15

Microplastic particles from Atlantic and Pacific Ocean trawls, lab-fed fish guts and ocean fish guts have been characterized using optical microscopy and SEM/EDS in terms of size, morphology, and chemistry. We assessed whether these measurements could serve as a rapid screening process for subsequent identification of the likely microplastic candidates by micro-spectroscopy. Optical microscopy enabled morphological classification of the types of particles or fibers present in the sample, as well as the quantification of particle size ranges and fiber lengths. SEM/EDS analysis was used to rule out non-plastic particles and screen the prepared samples for potential microplastic, based on their element signatures and surface characteristics. Chlorinated plastics such as polyvinyl chloride (PVC) could be easily identified with SEM/EDS due to their unique elemental signatures including chlorine, as could mineral species that are falsely identified as plastics by optical microscopy. Particle morphology determined by optical microscopy and SEM suggests the fish ingested particles contained both degradation fragments from larger plastic pieces and also manufactured microplastics. SEM images of microplastic particle surfaces revealed characteristic cracks consistent with environmental exposure, as well as pigment particles consistent with manufactured materials. Most of the microplastic surfaces in the fish guts and ocean trawls were covered with biofilms, radiolarians, and crustaceans. Many of the fish stomachs contained micro-shell pieces which visually resembled microplastics. Copyright © 2017 Elsevier B.V. All rights reserved.

Electrophoretic Deposition of Hydroxyapatite Film Containing Re-Doped MoS₂ Nanoparticles.

PubMed

Shalom, Hila; Feldman, Yishay; Rosentsveig, Rita; Pinkas, Iddo; Kaplan-Ashiri, Ifat; Moshkovich, Alexey; Perfilyev, Vladislav; Rapoport, Lev; Tenne, Reshef

2018-02-26

Films combining hydroxyapatite (HA) with minute amounts (ca. 1 weight %) of (rhenium doped) fullerene-like MoS₂ (IF) nanoparticles were deposited onto porous titanium substrate through electrophoretic process (EPD). The films were analyzed by scanning electron microscopy (SEM), X-ray diffraction and Raman spectroscopy. The SEM analysis showed relatively uniform coatings of the HA + IF on the titanium substrate. Chemical composition analysis using energy dispersive X-ray spectroscopy (EDS) of the coatings revealed the presence of calcium phosphate minerals like hydroxyapatite, as a majority phase. Tribological tests were undertaken showing that the IF nanoparticles endow the HA film very low friction and wear characteristics. Such films could be of interest for various medical technologies. Means for improving the adhesion of the film to the underlying substrate and its fracture toughness, without compromising its biocompatibility are discussed at the end.

3D imaging of cells and tissues by focused ion beam/scanning electron microscopy (FIB/SEM).

PubMed

Drobne, Damjana

2013-01-01

Integration of a scanning electron microscope (SEM) and focused ion beam (FIB) technology into a single FIB/SEM system permits use of the FIB as a nano-scalpel to reveal site-specific subsurface microstructures which can be examined in great detail by SEM. The FIB/SEM technology is widely used in the semiconductor industry and material sciences, and recently its use in the life sciences has been initiated. Samples for FIB/SEM investigation can be either embedded in a plastic matrix, the traditional means of preparation of transmission electron microscopy (TEM) specimens, or simply dried as in samples prepared for SEM imaging. Currently, FIB/SEM is used in the life sciences for (a) preparation by the lift-out technique of lamella for TEM analysis, (b) tomography of samples embedded in a matrix, and (c) in situ site-specific FIB milling and SEM imaging using a wide range of magnifications. Site-specific milling and imaging has attracted wide interest as a technique in structural research of single eukaryotic and prokaryotic cells, small animals, and different animal tissue, but it still remains to be explored more thoroughly. In the past, preparation of samples for site-specific milling and imaging by FIB/SEM has typically adopted the embedding techniques used for TEM samples, and which have been very well described in the literature. Sample preparation protocols for the use of dried samples in FIB/SEM have been less well investigated. The aim of this chapter is to encourage application of FIB/SEM on dried biological samples. A detailed description of conventional dried sample preparation and FIB/SEM investigation of dried biological samples is presented. The important steps are described and illustrated, and direct comparison between embedded and dried samples of same tissues is provided. The ability to discover links between gross morphology of the tissue or organ, surface characteristics of any selected region, and intracellular structural details on the nanometer scale is an appealing application of electron microscopy in the life sciences and merits further exploration.

Increased thyrotropin binding in hyperfunctioning thyroid nodules.

PubMed

Müller-Gärtner, H W; Schneider, C; Bay, V; Tadt, A; Rehpenning, W; de Heer, K; Jessel, M

1987-08-01

The object of this study was to investigate TSH receptors in hyperfunctioning thyroid nodules (HFN). In HFN, obtained from seven patients, 125-I-TSH binding as determined by equilibrium binding analysis on particulate membrane preparations, was found to be significantly increased as compared with normal thyroid tissues (five patients; P less than 0.001). Scatchard analysis of TSH-binding revealed two kinds of binding sites for both normal thyroid tissue and HFN, and displayed significantly increased association constants of high- and low-affinity binding sites in HFN (Ka = 11.75 +/- 6.8 10(9) M-1, P less than 0.001 and Ka = 2.1 +/- 1.0 10(7) M-1, P less than 0.025; x +/- SEM) as compared with normal thyroid tissue (Ka = 0.25 +/- 0.06 10(9) M-1, Ka = 0.14 +/- 0.03 10(7) M-1; x +/- SEM). The capacity of the high-affinity binding sites in HFN was found to be decreased (1.8 +/- 1.1 pmol/mg protein, x +/- SEM) in comparison with normal thyroid tissue (4.26 +/- 1.27 pmol/mg protein; x +/- SEM). TSH-receptor autoradiography applied to cryostatic tissue sections confirmed increased TSH binding of the follicular epithelium in HFN. These data suggest that an increased affinity of TSH-receptor sites in HFN in iodine deficient areas may be an important event in thyroid autonomy.

Comparing the detection of iron-based pottery pigment on a carbon-coated sherd by SEM-EDS and by Micro-XRF-SEM.

PubMed

Pendleton, Michael W; Washburn, Dorothy K; Ellis, E Ann; Pendleton, Bonnie B

2014-03-01

The same sherd was analyzed using a scanning electron microscope with energy dispersive spectroscopy (SEM-EDS) and a micro X-ray fluorescence tube attached to a scanning electron microscope (Micro-XRF-SEM) to compare the effectiveness of elemental detection of iron-based pigment. To enhance SEM-EDS mapping, the sherd was carbon coated. The carbon coating was not required to produce Micro-XRF-SEM maps but was applied to maintain an unbiased comparison between the systems. The Micro-XRF-SEM analysis was capable of lower limits of detection than that of the SEM-EDS system, and therefore the Micro-XRF-SEM system could produce elemental maps of elements not easily detected by SEM-EDS mapping systems. Because SEM-EDS and Micro-XRF-SEM have been used for imaging and chemical analysis of biological samples, this comparison of the detection systems should be useful to biologists, especially those involved in bone or tooth (hard tissue) analysis.

Comparing the Detection of Iron-Based Pottery Pigment on a Carbon-Coated Sherd by SEM-EDS and by Micro-XRF-SEM

PubMed Central

Pendleton, Michael W.; Washburn, Dorothy K.; Ellis, E. Ann; Pendleton, Bonnie B.

2014-01-01

The same sherd was analyzed using a scanning electron microscope with energy dispersive spectroscopy (SEM-EDS) and a micro X-ray fluorescence tube attached to a scanning electron microscope (Micro-XRF-SEM) to compare the effectiveness of elemental detection of iron-based pigment. To enhance SEM-EDS mapping, the sherd was carbon coated. The carbon coating was not required to produce Micro-XRF-SEM maps but was applied to maintain an unbiased comparison between the systems. The Micro-XRF-SEM analysis was capable of lower limits of detection than that of the SEM-EDS system, and therefore the Micro-XRF-SEM system could produce elemental maps of elements not easily detected by SEM-EDS mapping systems. Because SEM-EDS and Micro-XRF-SEM have been used for imaging and chemical analysis of biological samples, this comparison of the detection systems should be useful to biologists, especially those involved in bone or tooth (hard tissue) analysis. PMID:24600333

Multiple-Group Analysis Using the sem Package in the R System

ERIC Educational Resources Information Center

Evermann, Joerg

2010-01-01

Multiple-group analysis in covariance-based structural equation modeling (SEM) is an important technique to ensure the invariance of latent construct measurements and the validity of theoretical models across different subpopulations. However, not all SEM software packages provide multiple-group analysis capabilities. The sem package for the R…

Effect of endodontic irrigation with 1% sodium hypochlorite and 17% EDTA on primary teeth: a scanning electron microscope analysis.

PubMed

Ximenes, Marcos; Triches, Thaisa C; Beltrame, Ana Paula C A; Hilgert, Leandro A; Cardoso, Mariane

2013-01-01

This study evaluated the efficacy of 2 final irrigation solutions for removal of the smear layer (SL) from root canals of primary teeth, using scanning electron microscope (SEM) analysis. Thirty primary molars were selected and a single operator instrumented the canals. The initial irrigation was done with a 1% sodium hypochlorite (NaOCl) solution. After the preparation, the roots were randomly divided into 3 groups for final irrigation: Group 1, 1% NaOCl (n = 10); Group 2, 17% EDTA + 1% NaOCl (n = 10); and Group 3, 17% EDTA + saline solution (n = 10). The roots were prepared for SEM analysis (magnification 1000X). The photomicrographs were independently analyzed by 2 investigators with SEM experience, attributing scores to each root third in terms of SL removal. Kruskal-Wallis and Mann-Whitney tests revealed that there was no statistical difference between the groups (P = 0.489). However, a statistical difference was found (P < 0.05) in a comparison of root thirds, with the apical third having the worst results. Comparing the thirds within the same group, all canals showed statistical differences between the cervical and apical thirds (P < 0.05). The authors determined that no substance or association of substances were able to completely remove SL.

Characterization of wood dust from furniture by scanning electron microscopy and energy-dispersive x-ray analysis.

PubMed

Gómez Yepes, Milena Elizabeth; Cremades, Lázaro V

2011-01-01

Study characterized and analyzed form factor, elementary composition and particle size of wood dust, in order to understand its harmful health effects on carpenters in Quindío (Colombia). Once particle characteristics (size distributions, aerodynamic equivalent diameter (D(α)), elemental composition and shape factors) were analyzed, particles were then characterized via scanning electron microscopy (SEM) in conjunction with energy dispersive X-ray analysis (EDXRA). SEM analysis of particulate matter showed: 1) cone-shaped particle ranged from 2.09 to 48.79 µm D(α); 2) rectangular prism-shaped particle from 2.47 to 72.9 µm D(α); 3) cylindrically-shaped particle from 2.5 to 48.79 µm D(α); and 4) spherically-shaped particle from 2.61 to 51.93 µm D(α). EDXRA reveals presence of chemical elements from paints and varnishes such as Ca, K, Na and Cr. SEM/EDXRA contributes in a significant manner to the morphological characterization of wood dust. It is obvious that the type of particles sampled is a complex function of shapes and sizes of particles. Thus, it is important to investigate the influence of particles characteristics, morphology, shapes and D(α) that may affect the health of carpenters in Quindío.

Modeling of Individual and Organizational Factors Affecting Traumatic Occupational Injuries Based on the Structural Equation Modeling: A Case Study in Large Construction Industries

PubMed Central

Mohammadfam, Iraj; Soltanzadeh, Ahmad; Moghimbeigi, Abbas; Akbarzadeh, Mehdi

2016-01-01

Background Individual and organizational factors are the factors influencing traumatic occupational injuries. Objectives The aim of the present study was the short path analysis of the severity of occupational injuries based on individual and organizational factors. Materials and Methods The present cross-sectional analytical study was implemented on traumatic occupational injuries within a ten-year timeframe in 13 large Iranian construction industries. Modeling and data analysis were done using the structural equation modeling (SEM) approach and the IBM SPSS AMOS statistical software version 22.0, respectively. Results The mean age and working experience of the injured workers were 28.03 ± 5.33 and 4.53 ± 3.82 years, respectively. The portions of construction and installation activities of traumatic occupational injuries were 64.4% and 18.1%, respectively. The SEM findings showed that the individual, organizational and accident type factors significantly were considered as effective factors on occupational injuries’ severity (P < 0.05). Conclusions Path analysis of occupational injuries based on the SEM reveals that individual and organizational factors and their indicator variables are very influential on the severity of traumatic occupational injuries. So, these should be considered to reduce occupational accidents’ severity in large construction industries. PMID:27800465

Symposium U: Thermoelectric Power Generation. Held in Boston, Massachusetts on November 26-29, 2007

DTIC Science & Technology

2008-04-01

including X - ray /electron diffraction, TGA analysis, Raman / Fourier Transform Infrared Spectroscopy, electron microscopy, Rutherford back-scattering and...Energy dispersive X - ray analysis were performed on the treated sample. The results revealed that a surface layer (from 10 nm to up to micron in...nanoparticles into a matrix of bulk Bi2Te 3 material via a hot pressing process. These nanocomposites have been examined by SEM and X - ray powder

Discopersicus n. gen., a New Member of the Family Tylenchidae Örley, 1880 with Detailed SEM Study on Two Known Species of the Genus Discotylenchus Siddiqi, 1980 (Nematoda; Tylenchidae) from Iran.

PubMed

Yaghoubi, Ali; Pourjam, Ebrahim; Álvarez-Ortega, Sergio; Liébanas, Gracia; Atighi, Mohammad Reza; Pedram, Majid

2016-09-01

Discopersicus iranicus n. gen., n. comb., previously described from Iran as a new species under the genus Discotylenchus , is illustrated using light microscope and scanning electron microscope (SEM) observations and further studied using molecular characters. SEM studies revealed the newly proposed genus has oblique amphidial apertures on the lateral sides of the lip region. SEM images are also provided for two species of Discotylenchus , namely D. discretus and D. brevicaudatus , as the first SEM study of the genus . These results confirmed longitudinal amphidial aperture type on lateral sides of the lip region in genus Discotylenchus , as noted by Siddiqi while erecting the genus with D. discretus as the type species . Molecular phylogenetic analyses using partial small subunit (SSU) and large subunit (LSU) rDNA sequences revealed the affinity of the genus Discopersicus n. gen. with members of the subfamily Boleodorinae, as supported by morphological characters (mainly, the oblique amphidial opening).

Risk assessment of heavy metals in Vembanad Lake sediments (south-west coast of India), based on acid-volatile sulfide (AVS)-simultaneously extracted metal (SEM) approach.

PubMed

Shyleshchandran, Mohanachandran Nair; Mohan, Mahesh; Ramasamy, Eswara Venkatesaperumal

2018-03-01

Contamination of estuarine system due to heavy metals is a severe issue in tropical countries, especially in India. For the evaluation of the risk due to heavy metals, the current study assessed spatial and temporal variation of acid-volatile sulfide (AVS), simultaneously extracted metal (SEM), and total metal concentration as toxicity indicator of aquatic sediments in Vembanad Lake System (VLS), India. Surface sediment samples collected from 12 locations from the northern portion of VLS for 4 years during different seasons. The results suggest, in post-monsoon season, 91% of the sampling locations possessed high bioavailability of metals and results in toxicity to aquatic biota. The average seasonal distribution of SEM during the period of observations was in the order post-monsoon > pre-monsoon > monsoon (1.76 ± 2.00 > 1.35 ± 0.60 > 0.80 ± 0.54 μmol/g). The concentration of individual metals on ∑SEM are in the order SEM Zn > SEM Cu> SEM Cd ≈ SEM Pb > SEM Hg. Considering annual ΣSEM/AVS ratio, 83% of the sites cross the critical value of 'One,' reveals that active sulfide phase of the sediment for fixing the metals is saturated. The molar ratio (differences between SEM and AVS) and its normalized organic carbon ratio reveals that in the post-monsoon season, about 42% of the sites are in the category of adverse effects are possible. The study suggests the toxicity and mobility of the metals largely depend on the available AVS, and the current situation may pose harm to benthic organisms.

Three-dimensional architecture of ribosomal DNA within barley nucleoli revealed with electron microscopy.

PubMed

Iwano, Megumi; Che, Fang-Sik; Takayama, Seiji; Fukui, Kiichi; Isogai, Akira

2003-01-01

To elucidate the topological positioning of ribosomal RNA genes (rDNA) and nucleolar structure in three dimensions, we examined the localization of rDNA using in situ hybridization (ISH) analysis by scanning electron microscopy (SEM). The rDNA genes within the three-dimensional architecture of nucleoli were detected on chromatin fibers that connect a thick strand-like structure and a protrusion of rDNA into the inner nuclear hole where the nucleolus is formed. This novel use of ISH together with SEM is useful for the analysis of nucleolar structure in detail. Furthermore, rDNA was detected at the periphery of the fibrillar centers (FCs) of the nucleolus using immuno-gold labeling together with transmission electron microscopy (TEM). In situ hybridization with TEM confirmed that rDNA is naked and thus active in the FCs of nucleoli; ISH with SEM confirmed that rDNA is not covered with ribonucleo proteins at the protruding point and is thus inactive. We also show that the distribution pattern of FCs differs from sample to sample. These results indicate that rDNA is transcribed dynamically in a time- and region-specific manner over the course of the cell cycle.

Effect of Plasma Treatment on Air and Water-Vapor Permeability of Bamboo Knitted Fabric

NASA Astrophysics Data System (ADS)

Prakash, C.; Ramakrishnan, G.; Chinnadurai, S.; Vignesh, S.; Senthilkumar, M.

2013-11-01

In this paper, the effects of oxygen and atmospheric plasma on air and water-vapor permeability properties of single jersey bamboo fabric have been investigated. The changes in these properties are believed to be related closely to the inter-fiber and inter-yarn friction force induced by the plasma treatments. The outcomes showed that the water-vapor permeability increased, although the air permeability decreased along with the plasma treatments. The SEM images clearly showed that the plasma modified the fiber surface outwardly. The results showed that the atmospheric plasma has an etching effect and increases the functionality of a bamboo surface, which is evident from SEM and FTIR-ATR analysis. These results reveal that atmospheric pressure plasma treatment is an effective method to improve the performance of bamboo fabric. Statistical analysis also indicates that the results are significant for air permeability and water-vapor permeability of the plasma-treated bamboo fabric.

Electrophoretic Deposition of Hydroxyapatite Film Containing Re-Doped MoS2 Nanoparticles

PubMed Central

Shalom, Hila; Feldman, Yishay; Rosentsveig, Rita; Pinkas, Iddo; Kaplan-Ashiri, Ifat; Moshkovich, Alexey; Perfilyev, Vladislav; Rapoport, Lev

2018-01-01

Films combining hydroxyapatite (HA) with minute amounts (ca. 1 weight %) of (rhenium doped) fullerene-like MoS2 (IF) nanoparticles were deposited onto porous titanium substrate through electrophoretic process (EPD). The films were analyzed by scanning electron microscopy (SEM), X-ray diffraction and Raman spectroscopy. The SEM analysis showed relatively uniform coatings of the HA + IF on the titanium substrate. Chemical composition analysis using energy dispersive X-ray spectroscopy (EDS) of the coatings revealed the presence of calcium phosphate minerals like hydroxyapatite, as a majority phase. Tribological tests were undertaken showing that the IF nanoparticles endow the HA film very low friction and wear characteristics. Such films could be of interest for various medical technologies. Means for improving the adhesion of the film to the underlying substrate and its fracture toughness, without compromising its biocompatibility are discussed at the end. PMID:29495394

Thermo-structural analysis and electrical conductivity behavior of epoxy/metals composites

NASA Astrophysics Data System (ADS)

Boumedienne, N.; Faska, Y.; Maaroufi, A.; Pinto, G.; Vicente, L.; Benavente, R.

2017-05-01

This paper reports on the elaboration and characterization of epoxy resin filled with metallic particles powder (aluminum, tin and zinc) composites. The scanning electron microscopy (SEM) pictures, density measurements and x-ray diffraction analysis (DRX) showed a homogeneous phase of obtained composites. The differential scanning calorimetry revealed a good adherence at matrix-filler interfaces, confirming the SEM observations. The measured glass transition temperatures depend on composites fillers' nature. Afterwards, the electrical conductivity of composites versus their fillers' contents has been investigated. The obtained results depict a nonlinear behavior, indicating an insulator to conductor phase transition at a conduction threshold; with high contrast of ten decades. Hence, the elaborated materials give a possibility to obtain dielectric or electrically conducting phases, which can to be interesting in the choice of desired applications. Finally, the obtained results have been successfully simulated on the basis of different percolation models approach combined with structural characterization inferences.

Optimization of chemical displacement deposition of copper on porous silicon.

PubMed

Bandarenka, Hanna; Redko, Sergey; Nenzi, Paolo; Balucani, Marco; Bondarenko, Vitaly

2012-11-01

Copper (II) sulfate was used as a source of copper to achieve uniform distribution of Cu particles deposited on porous silicon. Layers of the porous silicon were formed by electrochemical anodization of Si wafers in a mixture of HF, C3H7OH and deionized water. The well-known chemical displacement technique was modified to grow the copper particles of specific sizes. SEM and XRD analysis revealed that the outer surface of the porous silicon was covered with copper particles of the crystal orientation inherited from the planes of porous silicon skeleton. The copper crystals were found to have the cubic face centering elementary cell. In addition, the traces of Cu2O cubic primitive crystalline phases were identified. The dimensions of Cu particles were determined by the Feret's analysis of the SEM images. The sizes of the particles varied widely from a few to hundreds of nanometers. A phenomenological model of copper deposition was proposed.

Scanning Electron Microscopy Investigation of a Sample Depth Profile Through the Martian Meteorite Nakhla

NASA Technical Reports Server (NTRS)

Toporski, Jan; Steele, Andrew; Westall, Frances; McKay, David S.

2000-01-01

The ongoing scientific debate as to whether or not the Martian meteorite ALH84001 contained evidence of possible biogenic activities showed the need to establish consistent methods to ascertain the origin of such evidence. To distinguish between terrestrial organic material/microbial contaminants and possible indigenous microbiota within meteorites is therefore crucial. With this in mind a depth profile consisting of four samples from a new sample allocation of Martian meteorite Nakhla was investigated using scanning electron microscopy (SEM) and energy dispersive X-ray analysis. SEM imaging of freshly broken fractured chips revealed structures strongly recent terrestrial microorganisms, in some cases showing evidence of active growth. This conclusion was supported by EDX analysis, which showed the presence of carbon associated with these structures, we concluded that these structures represent recent terrestrial contaminants rather than structures indigenous to the meteorite. Page

Sol-gel synthesis and characterizations of crystalline NaGd(WO4)2 powder for anisotropic transparent ceramic laser application

NASA Astrophysics Data System (ADS)

Durairajan, A.; Thangaraju, D.; Balaji, D.; Moorthy Babu, S.

2013-02-01

NaGd(WO4)2 powders were synthesized at different pH (3.5, 4.5, 5.5, 6.5 and 7.5) values by conventional Pechini method. Sodium and gadolinium nitrate salts and ammonium paratungstate are used as starting precursors. Metal cations were chelated by citric acid and individual citrates were bound together with ethylene glycol. Synthesized gel was analyzed using differential thermal analysis (DTA), thermo gravimetric (TG) and FT-IR spectroscopy to understand the degradation of gel and formation of metal citrates. Calcined powders (250, 600, 700 and 800 °C) were characterized by powder XRD, FT-IR, Raman and FE-SEM analysis. The temperature dependent phase formation was examined by powder XRD. The morphological changes at different pH derived powders were observed with FE-SEM micrographs. Stepwise organic liberation with respect to temperature and presence of carbon content in the pre-fired powder were analyzed using FT-IR analysis. Raman spectrum reveals disordered tungstate vibrations in the NGW matrix.

Effect of surface modified kaolin on properties of polypropylene grafted maleic anhydride

NASA Astrophysics Data System (ADS)

Yang, Ni; Zhang, Zuo-Cai; Ma, Ning; Liu, Huan-Li; Zhan, Xue-Qing; Li, Bing; Gao, Wei; Tsai, Fang-Chang; Jiang, Tao; Chang, Chang-Jung; Chiang, Tai-Chin; Shi, Dean

To achieve reinforcement of mechanical and thermal performances of polypropylene (PP) product, this work aimed at fabrication of surface modified kaolin (M-kaolin) filled polypropylene grafted maleic anhydride (PP-g-MAH) composites with varying contents of fillers and investigation of their mechanical and thermal properties. And the prepared PP-g-MAH/M-kaolin composites were characterized by means of Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM) and thermogravimetric analysis (TGA). Fracture analysis by SEM showed M-kaolin particles were well dispersed in the PP-g-MAH matrix. Mechanical behaviors were determined by tensile strength, tensile strain at break and impact strength analysis. Impact strength of PP-g-MAH/2 wt% M-kaolin composites was improved up to 30% comparing with unfilled composites. Thermostability had been found enhanced when M-kaolin added. The results revealed PP-g-MAH/M-kaolin composites showed the optimal thermal and mechanical properties when 2 wt% of M-kaolin was added.

Evaluation of poly (vinyl alcohol) based cryogel-zinc oxide nanocomposites for possible applications as wound dressing materials.

PubMed

Chaturvedi, Archana; Bajpai, Anil K; Bajpai, Jaya; K Singh, Sunil

2016-08-01

In this investigation cryogels composed of poly (vinyl alcohol) (PVA) were prepared by repeated freeze thaw method followed by in situ precipitation of zinc oxide nanoparticles within the cryogel networks. Fourier transformed infrared spectroscopy (FTIR), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and X-ray diffraction (XRD), Energy dispersive X-ray spectroscopy (EDX) were used to characterize the nanocomposites. The morphologies of native PVA cryogels and PVA cryogel-ZnO nanocomposites were observed by scanning electron microscopy (SEM), transmission electron microscopy (TEM) techniques. The SEM analysis suggested that cryogels show a well-defined porous morphology whereas TEM micrographs revealed the presence of nearly spherical and well separated zinc oxide nanoparticles with diameter<100nm. XRD results showed all relevant Bragg's reflections for crystal structure of zinc oxide nanoparticles. Thermo gravimetric-differential thermal analysis (TG-DTA) was conducted to evaluate thermal stability of the nanocomposites. Mechanical properties of nanocomposites were determined in terms of tensile strength and percent elongation. Biocompatible nature was ascertained by anti-haemolytic activity, bovine serum albumin (blood protein) adsorption and in vitro cytotoxicity tests. The prepared nanocomposites were also investigated for swelling and deswelling behaviours. The results revealed that both the swelling and deswelling process depend on the chemical composition of the nanocomposites, number of freeze-thaw cycles, pH and temperature of the swelling medium. The developed biocompatible PVA cryogel-ZnO nanocomposites were also tested for antibacterial activities against both Gram-negative and Gram-positive bacteria. Copyright © 2016 Elsevier B.V. All rights reserved.

FIB/SEM technology and high-throughput 3D reconstruction of dendritic spines and synapses in GFP-labeled adult-generated neurons.

PubMed

Bosch, Carles; Martínez, Albert; Masachs, Nuria; Teixeira, Cátia M; Fernaud, Isabel; Ulloa, Fausto; Pérez-Martínez, Esther; Lois, Carlos; Comella, Joan X; DeFelipe, Javier; Merchán-Pérez, Angel; Soriano, Eduardo

2015-01-01

The fine analysis of synaptic contacts is usually performed using transmission electron microscopy (TEM) and its combination with neuronal labeling techniques. However, the complex 3D architecture of neuronal samples calls for their reconstruction from serial sections. Here we show that focused ion beam/scanning electron microscopy (FIB/SEM) allows efficient, complete, and automatic 3D reconstruction of identified dendrites, including their spines and synapses, from GFP/DAB-labeled neurons, with a resolution comparable to that of TEM. We applied this technology to analyze the synaptogenesis of labeled adult-generated granule cells (GCs) in mice. 3D reconstruction of dendritic spines in GCs aged 3-4 and 8-9 weeks revealed two different stages of dendritic spine development and unexpected features of synapse formation, including vacant and branched dendritic spines and presynaptic terminals establishing synapses with up to 10 dendritic spines. Given the reliability, efficiency, and high resolution of FIB/SEM technology and the wide use of DAB in conventional EM, we consider FIB/SEM fundamental for the detailed characterization of identified synaptic contacts in neurons in a high-throughput manner.

FIB/SEM technology and high-throughput 3D reconstruction of dendritic spines and synapses in GFP-labeled adult-generated neurons

PubMed Central

Bosch, Carles; Martínez, Albert; Masachs, Nuria; Teixeira, Cátia M.; Fernaud, Isabel; Ulloa, Fausto; Pérez-Martínez, Esther; Lois, Carlos; Comella, Joan X.; DeFelipe, Javier; Merchán-Pérez, Angel; Soriano, Eduardo

2015-01-01

The fine analysis of synaptic contacts is usually performed using transmission electron microscopy (TEM) and its combination with neuronal labeling techniques. However, the complex 3D architecture of neuronal samples calls for their reconstruction from serial sections. Here we show that focused ion beam/scanning electron microscopy (FIB/SEM) allows efficient, complete, and automatic 3D reconstruction of identified dendrites, including their spines and synapses, from GFP/DAB-labeled neurons, with a resolution comparable to that of TEM. We applied this technology to analyze the synaptogenesis of labeled adult-generated granule cells (GCs) in mice. 3D reconstruction of dendritic spines in GCs aged 3–4 and 8–9 weeks revealed two different stages of dendritic spine development and unexpected features of synapse formation, including vacant and branched dendritic spines and presynaptic terminals establishing synapses with up to 10 dendritic spines. Given the reliability, efficiency, and high resolution of FIB/SEM technology and the wide use of DAB in conventional EM, we consider FIB/SEM fundamental for the detailed characterization of identified synaptic contacts in neurons in a high-throughput manner. PMID:26052271

Mechanical behavior and failure analysis of prosthetic retaining screws after long-term use in vivo. Part 4: Failure analysis of 10 fractured retaining screws retrieved from three patients.

PubMed

Al Jabbari, Youssef S; Fournelle, Raymond; Ziebert, Gerald; Toth, Jeffrey; Iacopino, Anthony M

2008-04-01

The aim of this study was to perform a failure analysis on fractured prosthetic retaining screws after long-term use in vivo. Additionally, the study addresses the commonly asked question regarding whether complex repeated functional occlusal forces initiate fatigue-type cracks in prosthetic retaining screws. Ten fractured prosthetic retaining screws retrieved from three patients treated with fixed detachable hybrid prostheses were subjected to a failure analysis. In patients 1 and 2, the middle three retaining screws of the prostheses were found fractured at retrieval time after they had been in service for 20 and 19 months, respectively. In patient 3, the middle three and one of the posterior retaining screws were found to be fractured at retrieval after they had been in service for 18 months. Low power stereomicroscopy and high-power scanning electron microscopy (SEM) were performed to analyze the fractured surfaces of the retaining screws examining fatigue cracks in greater detail. Typical fatigue failure characterized by ratchet mark formation was revealed by light microscopy and SEM for all examined screws. Using low magnification light microscopy, ratchet marks were visible on the fracture surfaces of only two screws. SEM examination revealed all three classical stages of fatigue failure, and it was possible to see the ratchet marks on the fracture surfaces of all specimens, indicating a fatigue zone. The final catastrophic overload fracture appeared fibrous, indicating ductile fracture. The final overload ductile fracture surfaces showed equiaxed dimples, suggesting tensile overload in all examined screws except in two specimens that showed an elongated dimple pattern indicating shear/tearing overload forces. Fracture of prosthetic retaining screws in hybrid prostheses occurs mainly through a typical fatigue mode involving mostly the middle anterior three screws. Fatigue cracks can grow in more than one prosthetic retaining screw, leading to fracture before the patient or clinician determines that any problem exists.

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

Multifunctional Polymers and Composites for Self-Healing Applications

DTIC Science & Technology

2006-09-30

linkages (Chen et al. 2002), and a phase separated system based on polydimethylsiloxane (Cho et al. 2006). Self-healing occurs when monomer is released...WCI6 is shown in Figure 1.1a. The average particle sizes determined by analysis of SEM images for all three delivery methods are listed in Table 1.1...were then sieved and the beads smaller than 355 um were kept for further study. Elemental analysis of the wax beads revealed that the concentration of

A facile synthesis of metal nanoparticle - graphene composites for better absorption of solar radiation

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

Sharma, Bindu; Mulla, Rafiq; Rabinal, M. K., E-mail: mkrabinal@yahoo.com

2015-06-24

Herein, a facile chemical approach has been adopted to prepare silver nanoparticles (AgNPs)- graphene (G) composite to study photothermal effect. Sodium borohydride (SBH), a strong reducing agent has been selected for this work. Effect of SBH concentrations on optical behavior of AgNPs-G composite was also investigated. Resultant materials were characterized by various techniques including X-ray diffraction (XRD), fourier transform infrared spectroscopy (FTIR), optical absorption, scanning electron microscopy (SEM) and transmission electron microscopy (TEM). SEM micrographs confirm wrapping of AgNPs into graphene whereas XRD analysis reveals their particle size variation between 47 nm to 69 nm. Optical studies throw a light on theirmore » strong absorption behavior towards solar radiation.« less

Nanoplate-like tungsten trioxide (hydrate) films prepared by crystal-seed-assisted hydrothermal reaction

NASA Astrophysics Data System (ADS)

Wang, P.; Yang, L.; Dai, B.; Yang, Z.; Guo, S.; Zhu, J.

2017-07-01

Vertically-aligned WO3 nanoplates on transparent conducting fluorine-doped tin oxide (FTO) glass were prepared by a facile template-free crystal-seed-assisted hydrothermal method. The effects of the hydrothermal temperature and reaction time on the crystal structure and morphology of the products were investigated by XRD and SEM. The XRD results showed that the as-prepared thin films obtained below 150∘C comprised orthorhombic WO3 ṡ H2O and completely converted to monoclinic WO3 at 180∘C. It was also noted that there was a phase transformation from orthorhombic to monoclinic by increasing the reaction time from 1 to 12 h. SEM analysis revealed that WO3 thin films are composed of plate-like nanostructures.

Preparation of poly (arylene ether nitrile)/NzdFeB composite film with excellent thermal properties and tensile strength

NASA Astrophysics Data System (ADS)

Pan, Hai; Xu, Mingzhen; Liu, Xiaobo

2017-12-01

PEN/NdFeB composite films were prepared by the solution casting method. The thermal properties, fracture morphology and tensile strength of the composite films were tested by DSC, TGA, SEM and electromechanical universal testing machine, respectively. The results reveal that the composite film has good thermal properties and tensile strength. Glass-transition temperature and decomposition temperatures at weight loss of 5% ot the composite films retain at 166±1 C and 462±4 C, respectively. The composite film with 5 wt.% NdFeB has the best tensile strength value for 100.5 MPa. In addition, it was found that the NdFeB filler was well dispersed in PEN matrix by SEM analysis.

Inhibitive effect of Xylopia ferruginea extract on the corrosion of mild steel in 1M HCl medium

NASA Astrophysics Data System (ADS)

Raja, Pandian Bothi; Rahim, Afidah Abdul; Osman, Hasnah; Awang, Khalijah

2011-08-01

The alkaloid content of the leaves and stem bark of Xylopia ferruginea plant was isolated and tested for its anticorrosion potential on mild steel corrosion in a hydrochloric acid medium by using electrochemical impedance spectroscopy, potentiodynamic polarization measurement, scanning electron microscopy (SEM), and Fourier transform infra red (FTIR) analysis. The experimental results reveal the effective anticorrosion potential of the plant extract. The mixed mode of action exhibited by the plant extract is evidenced from the polarization study. SEM images proof the formation of a protective layer over the mild steel surface, and this is supported by the FTIR study. The possible mode of the corrosion inhibition mechanism has also been discussed.

Method variation in the impact of missing data on response shift detection.

PubMed

Schwartz, Carolyn E; Sajobi, Tolulope T; Verdam, Mathilde G E; Sebille, Veronique; Lix, Lisa M; Guilleux, Alice; Sprangers, Mirjam A G

2015-03-01

Missing data due to attrition or item non-response can result in biased estimates and loss of power in longitudinal quality-of-life (QOL) research. The impact of missing data on response shift (RS) detection is relatively unknown. This overview article synthesizes the findings of three methods tested in this special section regarding the impact of missing data patterns on RS detection in incomplete longitudinal data. The RS detection methods investigated include: (1) Relative importance analysis to detect reprioritization RS in stroke caregivers; (2) Oort's structural equation modeling (SEM) to detect recalibration, reprioritization, and reconceptualization RS in cancer patients; and (3) Rasch-based item-response theory-based (IRT) models as compared to SEM models to detect recalibration and reprioritization RS in hospitalized chronic disease patients. Each method dealt with missing data differently, either with imputation (1), attrition-based multi-group analysis (2), or probabilistic analysis that is robust to missingness due to the specific objectivity property (3). Relative importance analyses were sensitive to the type and amount of missing data and imputation method, with multiple imputation showing the largest RS effects. The attrition-based multi-group SEM revealed differential effects of both the changes in health-related QOL and the occurrence of response shift by attrition stratum, and enabled a more complete interpretation of findings. The IRT RS algorithm found evidence of small recalibration and reprioritization effects in General Health, whereas SEM mostly evidenced small recalibration effects. These differences may be due to differences between the two methods in handling of missing data. Missing data imputation techniques result in different conclusions about the presence of reprioritization RS using the relative importance method, while the attrition-based SEM approach highlighted different recalibration and reprioritization RS effects by attrition group. The IRT analyses detected more recalibration and reprioritization RS effects than SEM, presumably due to IRT's robustness to missing data. Future research should apply simulation techniques in order to make conclusive statements about the impacts of missing data according to the type and amount of RS.

Graphene-supporting films and low-voltage STEM in SEM toward imaging nanobio materials without staining: Observation of insulin amyloid fibrils.

PubMed

Ogawa, Takashi; Gang, Geun Won; Thieu, Minh Thu; Kwon, Hyuksang; Ahn, Sang Jung; Ha, Tai Hwan; Cho, Boklae

2017-05-01

Utilization of graphene-supporting films and low-voltage scanning transmission electron microscopy (LV-STEM) in scanning electron microscopy (SEM) is shown to be an effective means of observing unstained nanobio materials. Insulin amyloid fibrils, which are implicated as a cause of type II diabetes, are formed in vitro and observed without staining at room temperature. An in-lens cold field-emission SEM, equipped with an additional homemade STEM detector, provides dark field (DF)-STEM images in the low energy range of 5-30keV, together with secondary electron (SE) images. Analysis based on Lenz's theory is used to interpret the experimental results. Graphene films, where the fibrils are deposited, reduce the background level of the STEM images compared with instances when conventional amorphous carbon films are used. Using 30keV, which is lower than that for conventional TEM (100-300keV), together with low detection angles (15-55mrad) enhances the signals from the fibrils. These factors improve image quality, which enables observation of thin fibrils with widths of 7-8nm. STEM imaging clearly reveals a twisted-ribbon structure of a fibril, and SE imaging shows an emphasized striped pattern of the fibril. The LV-STEM in SEM enables acquisition of two types of images of an identical fibril in a single instrument, which is useful for understanding the structure. This study expands the application of SEM to other systems of interest, which is beneficial to a large number of users. The method in this study can be applied to the observation of various nanobio materials and analysis of their native structures, thus contributing to research in materials and life sciences. Copyright © 2017 Elsevier Ltd. All rights reserved.

Synthesis, characterization and visible-light driven photocatalysis by differently structured CdS/ZnS sandwich and core-shell nanocomposites

NASA Astrophysics Data System (ADS)

Qutub, Nida; Pirzada, Bilal Masood; Umar, Khalid; Mehraj, Owais; Muneer, M.; Sabir, Suhail

2015-11-01

CdS/ZnS sandwich and core-shell nanocomposites were synthesized by a simple and modified Chemical Precipitation method under ambient conditions. The synthesized composites were characterized by XRD, SEM, TEM, EDAX and FTIR. Optical properties were analyzed by UV-vis. Spectroscopy and the photoluminescence study was done to monitor the recombination of photo-generated charge-carriers. Thermal stability of the synthesized composites was analyzed by Thermal Gravimetric Analysis (TGA). XRD revealed the formation of nanocomposites as mixed diffraction peaks were observed in the XRD pattern. SEM and TEM showed the morphology of the nanocomposites particles and their fine particle size. EDAX revealed the appropriate molar ratios exhibited by the constituent elements in the composites and FTIR gave some characteristic peaks which indicated the formation of CdS/ZnS nanocomposites. Electrochemical Impedance Spectroscopy was done to study charge transfer properties along the nanocomposites. Photocatalytic properties of the synthesized composites were monitored by the photocatalytic kinetic study of Acid Blue dye and p-chlorophenol under visible light irradiation. Results revealed the formation of stable core-shell nanocomposites and their efficient photocatalytic properties.

Synthesis of Carbon Nanotubes and Nanospheres from Coconut Fibre and the Role of Synthesis Temperature on Their Growth

NASA Astrophysics Data System (ADS)

Adewumi, Gloria A.; Inambao, Freddie; Eloka-Eboka, Andrew; Revaprasadu, Neerish

2018-07-01

Carbon nanotubes (CNT) and carbon nanospheres were successfully synthesized from coconut fibre-activated carbon. The biomass was first carbonized then physically activated, followed by treatment using ethanol vapor at 700°C to 1100°C at 100°C intervals. The effect of synthesis temperature on the formation of the nanomaterials was studied using scanning electron microscopy (SEM), transmission electron microscopy (TEM), energy dispersive x-ray spectrometry, x-ray diffraction (XRD), Fourier transform infrared microscopy (FTIR) and thermogravimetric analysis. SEM analysis revealed that nanospheres were formed at higher temperatures of 1000°C and 1100°C, while lower temperatures of 800°C and 900°C favored the growth of CNT. At 700°C, however, no tubes or spheres were formed. TEM and FTIR were used to observe spectral features, such as the peak positions, intensity and bandwidth, which are linked to some structural properties of the samples investigated. All these observations provided facts on the nanosphere and nanotube dimensions, vibrational modes and the degree of purity of the obtained samples. The TEM results show spheres of diameter in the range 50 nm to 250 nm while the tubes had diameters between 50 nm to 100 nm. XRD analysis reveals the materials synthesized are amorphous in nature with a hexagonal graphite structure.

Synthesis of Carbon Nanotubes and Nanospheres from Coconut Fibre and the Role of Synthesis Temperature on Their Growth

NASA Astrophysics Data System (ADS)

Adewumi, Gloria A.; Inambao, Freddie; Eloka-Eboka, Andrew; Revaprasadu, Neerish

2018-04-01

Carbon nanotubes (CNT) and carbon nanospheres were successfully synthesized from coconut fibre-activated carbon. The biomass was first carbonized then physically activated, followed by treatment using ethanol vapor at 700°C to 1100°C at 100°C intervals. The effect of synthesis temperature on the formation of the nanomaterials was studied using scanning electron microscopy (SEM), transmission electron microscopy (TEM), energy dispersive x-ray spectrometry, x-ray diffraction (XRD), Fourier transform infrared microscopy (FTIR) and thermogravimetric analysis. SEM analysis revealed that nanospheres were formed at higher temperatures of 1000°C and 1100°C, while lower temperatures of 800°C and 900°C favored the growth of CNT. At 700°C, however, no tubes or spheres were formed. TEM and FTIR were used to observe spectral features, such as the peak positions, intensity and bandwidth, which are linked to some structural properties of the samples investigated. All these observations provided facts on the nanosphere and nanotube dimensions, vibrational modes and the degree of purity of the obtained samples. The TEM results show spheres of diameter in the range 50 nm to 250 nm while the tubes had diameters between 50 nm to 100 nm. XRD analysis reveals the materials synthesized are amorphous in nature with a hexagonal graphite structure.

Estimation and comparison of cumulative incidences of biliary self-expandable metallic stent dysfunction accounting for competing risks.

PubMed

Hamada, Tsuyoshi; Nakai, Yousuke; Isayama, Hiroyuki; Togawa, Osamu; Kogure, Hirofumi; Kawakubo, Kazumichi; Tsujino, Takeshi; Sasahira, Naoki; Hirano, Kenji; Yamamoto, Natsuyo; Ito, Yukiko; Sasaki, Takashi; Mizuno, Suguru; Toda, Nobuo; Tada, Minoru; Koike, Kazuhiko

2014-03-01

Self-expandable metallic stent (SEMS) placement is widely carried out for distal malignant biliary obstruction, and survival analysis is used to evaluate the cumulative incidences of SEMS dysfunction (e.g. the Kaplan-Meier [KM] method and the log-rank test). However, these statistical methods might be inappropriate in the presence of 'competing risks' (here, death without SEMS dysfunction), which affects the probability of experiencing the event of interest (SEMS dysfunction); that is, SEMS dysfunction can no longer be observed after death. A competing risk analysis has rarely been done in studies on SEMS. We introduced the concept of a competing risk analysis and illustrated its impact on the evaluation of SEMS outcomes using hypothetical and actual data. Our illustrative study included 476 consecutive patients who underwent SEMS placement for unresectable distal malignant biliary obstruction. A significant difference between cumulative incidences of SEMS dysfunction in male and female patients via theKM method (P = 0.044 by the log-rank test) disappeared after applying a competing risk analysis (P = 0.115 by Gray's test). In contrast, although cumulative incidences of SEMS dysfunction via the KM method were similar with and without chemotherapy (P = 0.647 by the log-rank test), cumulative incidence of SEMS dysfunction in the non-chemotherapy group was shown to be significantly lower (P = 0.031 by Gray's test) in a competing risk analysis. Death as a competing risk event needs to be appropriately considered in estimating a cumulative incidence of SEMS dysfunction, otherwise analytical results may be biased. © 2013 The Authors. Digestive Endoscopy © 2013 Japan Gastroenterological Endoscopy Society.

Roughness-controlled self-assembly of mannitol/LB agar microparticles by polymorphic transformation for pulmonary drug delivery.

PubMed

Zhang, Fengying; Ngoc, Nguyen Thi Quynh; Tay, Bao Hui; Mendyk, Aleksander; Shao, Yu-Hsuan; Lau, Raymond

2015-01-05

Novel roughness-controlled mannitol/LB Agar microparticles were synthesized by polymorphic transformation and self-assembly method using hexane as the polymorphic transformation reagent and spray-dried mannitol/LB Agar microparticles as the starting material. As-prepared microparticles were characterized by Fourier transform infrared spectra (FTIR), X-ray diffraction spectra (XRD), differential scanning calorimetry (DSC), scanning electron microscopy (SEM), thermal gravimetric analysis (TGA), and Andersen Cascade Impactor (ACI). The XRD and DSC results indicate that after immersing spray-dried mannitol/LB Agar microparticles in hexane, β-mannitol was completely transformed to α-mannitol in 1 h, and all the δ-mannitol was transformed to α form after 14 days. SEM shows that during the transformation the nanobelts on the spray-dried mannitol/LB Agar microparticles become more dispersed and the contour of the individual nanobelts becomes more noticeable. Afterward, the nanobelts self-assemble to nanorods and result in rod-covered mannitol/LB Agar microparticles. FTIR indicates new hydrogen bonds were formed among mannitol, LB Agar, and hexane. SEM images coupled with image analysis software reveal that different surface morphology of the microparticles have different drug adhesion mechanisms. Comparison of ACI results and image analysis of SEM images shows that an increase in the particle surface roughness can increase the fine particle fractions (FPFs) using the rod-covered mannitol microparticles as drug carriers. Transformed microparticles show higher FPFs than commercially available lactose carriers. An FPF of 28.6 ± 2.4% was achieved by microparticles transformed from spray-dried microparticles using 2% mannitol(w/v)/LB Agar as feed solution. It is comparable to the highest FPF reported in the literature using lactose and spray-dried mannitol as carriers.

SEM observation on microbial like structure in the ferromanganese crust from the western Pacific Magellan Seamount

NASA Astrophysics Data System (ADS)

Yang, K.; Park, H.; Baik, H.; Kim, J.; Park, K. R.; Yoon, J.; Kim, J. W.

2016-12-01

Understanding the biogeochemical process in the Fe-Mn crust layer is important to reconstruct the paleo-environment when the Fe-Mn crust layer forms. Scanning Electron Microscopy (SEM), Transmission Electron Microscopy (TEM), Electron Energy Loss Spectroscopy (EELS), and Polymerase Chain Reaction (PCR) were utilized to determine the redox states of Fe/Mn and microbial diversity at each layer. Samples were dredged from the western Pacific Magellan Seamount (OSM11) that consists of five well-defined layers from the rim (L1) to the core (L5). Some microbial like structures of sheath-like with filaments (L1 - L3), capsule-shaped (L2), fossilized coccolith mounds with phosphatized globules (L4), and bean-shaped (L4) were detected in entire layers. The cross sectional observation of bean-shaped microbe like structures encrusted with Fe-vernadite (L3) by Scanning Transmission Electron Microscopy (STEM) and Focused Ion Beam (FIB) technique revealed 1-μm diameter cavity in the center and porous structures of encrusting Fe-vernadite in periphery. Moreover, the organic carbon in the center cavity compared with inorganic C (from carbonate) in periphery was differentiated by C-K edge EELS spectra, suggesting that the microbe used to occupy. Indeed, the PCR analysis indicated the presence of functional gene (cumA; 1056bp & coxC; 810bp) association with Mn & Fe oxidizer that promote the formation of the crust. The cloning and sequencing of DNA PCR fragments revealed the appearance of geobacter species in L3 (G. sulfurreducens and G. lovleyi). The DNA molecular biological analysis and SEM direct observations suggest the evidence of biotic process in the formation of Fe-Mn crust.

Antagonistic effects of Bacillus subtilis subsp. subtilis and B. amyloliquefaciens against Macrophomina phaseolina: SEM study of fungal changes and UV-MALDI-TOF MS analysis of their bioactive compounds.

PubMed

Torres, M J; Brandan, C Pérez; Petroselli, G; Erra-Balsells, R; Audisio, M C

2016-01-01

The antifungal effect of Bacillus subtilis subsp. subtilis PGPMori7 and Bacillus amyloliquefaciens PGPBacCA1 was evaluated against Macrophomina phaseolina (Tassi) Goid. Cell suspension (CS), cell-free supernatant (CFS) and the lipopeptide fraction (LF) of PGPMori7 and PGPBacCA1 were screened against three different M. phaseolina strains. CS exhibited the highest inhibitory effect (around 50%) when compared to those of CFS and LF, regardless of the fungal strain studied. The synthesis of lipopeptides was studied by UV-MALDI TOF. Chemical analysis of Bacillus metabolite synthesis revealed that surfactin and iturin were mainly produced in liquid medium. Potential fengycin was also co-produced when both Bacillus were cultivated in solid medium. In co-culture assays, the bacterial colony-fungal mycelium interface at the inhibition zone was evaluated by both scanning electron microscopy (SEM) and UV-MALDI TOF, the former to determine the structural changes on M. phaseolina cells and the latter to identify the main bioactive molecules involved in the inhibitory effect. PGPBacCA1 produced surfactin, iturin and fengycin in the inhibition zone while PGPMori7 only produced these metabolites within its colony and not in the narrow inhibition zone. Interestingly, SEM revealed that PGPBacCA1 induced damage in M. phaseolina sclerotia, generating a fungicidal effect as no growth was observed when normal growth conditions were reestablished. In turn, PGPMori7 inhibited the growth of the Macrophomina mycelium without fungal injury, resulting only in a fungistatic activity. From these results, it was determined that the two bacilli significantly inhibited the growth of an important phytopathogenic fungus by at least two different mechanisms: lipopeptide synthesis and competition among microorganisms. Copyright © 2015 Elsevier GmbH. All rights reserved.

In-situ laser-induced synthesis of associated YVO4:Eu3+@SiO2@Au-Ag/C nanohybrids with enhanced luminescence

NASA Astrophysics Data System (ADS)

Kolesnikov, I. E.; lvanova, T. Yu.; Ivanov, D. A.; Kireev, A. A.; Mamonova, D. V.; Golyeva, E. V.; Mikhailov, M. D.; Manshina, A. A.

2018-02-01

Associated luminescence/plasmonic nanoparticles were prepared in a single step process as a result of laser illumination (low intensity CW He-Cd laser) of colloidal solution of YVO4:Eu3+@SiO2 mixed with heterometallic supramolecular complex. The results of SEM-EDX analysis, absorption, steady-state luminescence and luminescence decay measurements revealed formation of associated nanohybrids with core/shell morphology. The obtained nanostructures demonstrated metal enhanced luminescence with enhancement factor of 1.6. The theoretical calculations revealed strong correlation of enhancement factor and plasmonic nanoparticles number.

The synthesis of Ba2+ doped multiferroic BiFeO3 nanoparticles by using a hydrothermal approach in the presence of different surface activators and the investigation of structural and magnetic features

NASA Astrophysics Data System (ADS)

Mardani, Reza

2017-05-01

In this work, Bi1-x Ba x FeO3 nanoparticles were synthesized by a hydrothermal method in the presence of various surface activators, and different amounts of barium were inserted in a bismuth ferrite (x  =  0.1, 0.15, 0.2) structure instead of bismuth. The structural and magnetic properties, morphology, and size of the synthesized nanoparticles were investigated by XRD, FT-IR, FE-SEM, TEM, DLS and VSM. The XRD analysis results reveal that the synthetic nanoparticles have a single phase. A phase shift from a rhombohedral structure to a tetragonal structure occurs due to the enhanced barium amount in the bismuth ferrite structure. The SEM analysis exhibits a uniform shape of the Bi0.85Ba0.15FeO3 particles and the image observed by TEM clarifies the size of the particles as 11 nm. Furthermore, the effect of the diverse surfaces of activators in the synthesis of Bi0.85Ba0.15FeO3 nanoparticles was studied, revealing that when sugar was used as a surfactant, the particle size reduced and the magnetic properties increased notably.

Synthesis of functional ceramic supports by ice templating and atomic layer deposition

NASA Astrophysics Data System (ADS)

Klotz, Michaela; Weber, Matthieu; Deville, Sylvain; Oison, Didier; Iatsunskyi, Igor; Coy, Emerson; Bechelany, Mikhael

2018-05-01

In this work, we report an innovative route for the manufacturing of functional ceramic supports, by combining ice templating of yttria stabilized zirconia (YSZ) and atomic layer deposition (ALD) of Al2O3 processes. Ceramic YSZ monoliths are prepared using the ice-templating process, which is based on the controlled crystallization of water following a thermal gradient. Sublimation of the ice and the sintering of the material reveal the straight micrometer sized pores shaped by the ice crystal growth. The high temperature sintering allows for the ceramic materials to present excellent mechanical strength and porosities of 67%. Next, the conformality benefit of ALD is used to deposit an alumina coating at the surface of the YSZ pores, in order to obtain a functional material. The Al2O3 thin films obtained by ALD are 100 nm thick and conformally deposited within the macroporous ceramic supports, as shown by SEM and EDS analysis. Mercury intrusion experiments revealed a reduction of the entrance pore diameter, in line with the growth per cycle of 2 Å of the ALD process. In addition to the manufacture of the innovative ceramic nanomaterials, this article also describes the fine characterization of the coatings obtained using mercury intrusion, SEM and XRD analysis.

Silicone intraocular lens surface calcification in a patient with asteroid hyalosis.

PubMed

Matsumura, Kazuhiro; Takano, Masahiko; Shimizu, Kimiya; Nemoto, Noriko

2012-07-01

To confirm a substance presence on the posterior intraocular lens (IOL) surface in a patient with asteroid hyalosis. An 80-year-old man had IOLs for approximately 12 years. Opacities and neodymium-doped yttrium aluminum garnet pits were observed on the posterior surface of the right IOL. Asteroid hyalosis and an epiretinal membrane were observed OD. An IOL exchange was performed on 24 March 2008, and the explanted IOL was analyzed using a light microscope and a transmission electron microscope with a scanning electron micrograph and an energy-dispersive X-ray spectrometer for elemental analysis. To confirm asteroid hyalosis, asteroid bodies were examined with the ionic liquid (EtMeIm+ BF4-) method using a field emission scanning electron microscope (FE-SEM) with digital beam control RGB mapping. X-ray spectrometry of the deposits revealed high calcium and phosphorus peaks. Spectrometry revealed that the posterior IOL surface opacity was due to a calcium-phosphorus compound. Examination of the asteroid bodies using FE-SEM with digital beam control RGB mapping confirmed calcium and phosphorus as the main components. Calcium hydrogen phosphate dihydrate deposits were probably responsible for the posterior IOL surface opacity. Furthermore, analysis of the asteroid bodies demonstrated that calcium and phosphorus were its main components.

Measuring motivation and volition of nursing students in nontraditional learning environments.

PubMed

Nagelsmith, Laurie; Bryer, Jason; Yan, Zheng

2012-01-01

The purpose of this study was to identify the best fitting model to represent interrelationships between motivation, volition, and academic success for adult nursing students learning in nontraditional environments. Participants (N=297) completed a survey that incorporated two measures: the Motivated Strategies for Learning Questionnaire (MSLQ) and the academic volitional strategies inventory (AVSI) as well as demographic information. Exploratory factor analysis (EFA), confirmatory factor analysis (CFA), and structural equation modeling (SEM) were used for data analysis. In phase 1, EFA resulted in factors that generally aligned with previous theoretical factors as defined by the psychometrics used. In Phase 2 of the analysis, CFA validated the use of predefined factor structures. In Phase 3, SEM analysis revealed that motivation has a larger effect on grade point average (GPA; beta = .28, p < .01) than volition (beta = .15, p < .05). The covariance between motivation and volition (r = .42, p < .01) was also found to be significant. These results suggest that there is a significant relationship among motivation, volition, and academic success for adult learners studying in nontraditional learning environments. These findings are consistent with and elaborate the relationship between motivation and volition with a population and setting underrepresented in the research.

Green engineering of biomolecule-coated metallic silver nanoparticles and their potential cytotoxic activity against cancer cell lines

NASA Astrophysics Data System (ADS)

Prasannaraj, Govindaraj; Venkatachalam, Perumal

2017-06-01

This report describes the synthesis of metallic silver nanoparticles (AgNPs) using extracts of four medicinal plants (Aegle marmelos (A. marmelos), Alstonia scholaris (A. scholaris), Andrographis paniculata (A. paniculata) and Centella asiatica (C. asiatica)). The bio-conjugates were characterized by UV-visible spectroscopy, scanning electron microscopy-energy dispersive spectroscopy (SEM-EDS), Fourier transform infrared spectrometry (FTIR), x-ray diffraction (XRD) and zeta potential. This analysis confirmed that UV-Vis spectral peaks at 375 nm, 380 nm, 420 nm and 380 nm are corresponding to A. marmelos, A. scholaris, A. paniculata and C. asiatica mediated AgNPs, respectively. SEM images revealed that all the obtained four AgNPs are predominantly spherical, fibres and rectangle in shape with an average size of 36-97 nm. SEM-EDS and XRD analysis confirmed the presence of elemental AgNPs in crystalline form for all the four nanoparticle samples. The phytochemicals of various medicinal plant extracts with different functional groups were responsible for reduction of Ag+ to AgNPs, which act as capping and stabilizing agent. Among four types of AgNPs tested for anticancer activity, the Ap mediated AgNPs had shown enhanced activity against HepG2 cells (27.01 µg ml-1) and PC3 cells (32.15 µg ml-1).

How Hedstrom files fail during clinical use? A retrieval study based on SEM, optical microscopy and micro-XCT analysis.

PubMed

Zinelis, Spiros; Al Jabbari, Youssef S

2018-05-01

This study was conducted to evaluate the failure mechanism of clinically failed Hedstrom (H)-files. Discarded H-files (n=160) from #8 to #40 ISO sizes were collected from different dental clinics. Retrieved files were classified according to their macroscopic appearance and they were investigated under scanning electron microscopy (SEM) and X-ray micro-computed tomography (mXCT). Then the files were embedded in resin along their longitudinal axis and after metallographic grinding and polishing, studied under an incident light microscope. The macroscopic evaluation showed that small ISO sizes (#08-#15) failed by extensive plastic deformation, while larger sizes (≥#20) tended to fracture. Light microscopy and mXCT results coincided showing that unused and plastically deformed files were free of internal defects, while fractured files demonstrate the presence of intense cracking in the flute region. SEM analysis revealed the presence of striations attributed to the fatigue mechanism. Secondary cracks were also identified by optical microscopy and their distribution was correlated to fatigue under bending loading. Experimental results demonstrated that while overloading of cutting instruments is the predominating failure mechanism of small file sizes (#08-#15), fatigue should be considered the fracture mechanism for larger sizes (≥#20).

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

Vilches, J.; Lopez, A.; Martinez, M.C.

This paper discusses the value of scanning electron microscopy (SEM) and x-ray microanalysis in the classification of craniopharyngiomas. This neoplasm shows epithelial nest, cords of cuboid cells, foci of squamous metaplasia, and microcystic degeneration. SEM reveals that the epithelial cysts are lined with elongated cells that possess numerous microvilli and blebs and that some cysts are lined with polyhedral cells. The microvilli are interpreted as characteristic of the fast growing craniopharyngiomas. A microanalytical study of the calcified areas reveals the presence of magnesium, phosphorus, and calcium.

Studies on the Inhibition of Mild Steel Corrosion by Rauvolfia serpentina in Acid Media

NASA Astrophysics Data System (ADS)

Bothi Raja, P.; Sethuraman, M. G.

2010-07-01

Alkaloid extract of Rauvolfia serpentina was tested as corrosion inhibitor for mild steel in 1 M HCl and H2SO4 using weight loss method at three different temperatures, viz., 303, 313, and 323 K, potentiodynamic polarization, electrochemical impedance spectroscopy and scanning electron microscope (SEM) studies. It is evident from the results of this study that R. serpentina effectively inhibits the corrosion in both the acids through adsorption process following Tempkin adsorption isotherm. The protection efficiency increased with increase in inhibitor concentration and temperature. Free energy of adsorption calculated from the temperature studies also revealed the chemisorption. The mixed mode of action exhibited by the inhibitor was confirmed by the polarization studies while SEM analysis substantiated the formation of protective layer over the mild steel surface.

Phase study and surface morphology of beta-alumina

NASA Astrophysics Data System (ADS)

Tak, S. K.

2018-05-01

Beta alumina ceramic is well known as a polycrystalline ceramic material. The characteristic crystal structure of beta-alumina makes it useful as a separator in sodium sulphur batteries and other electrochemical devices requiring the passage of sodium ions. β"-alumina powders for this study were prepared by zeta process. The pellets were sintered at different microwave power levels and power schedule to optimize the sintering conditions to obtain preferred β" phase with improved microstructure. Phase identification was studied by X-ray diffraction (XRD). XRD analysis shows increase in β'' phase as the sintering temperature was increased from 1400°C to 1600°C. Surface morphology of the pellets was carried out by Scanning Electron microscopy (SEM). SEM studies revealed the formation and growth of platelet grains with interconnected porosity.

In Search of Search Engine Marketing Strategy Amongst SME's in Ireland

NASA Astrophysics Data System (ADS)

Barry, Chris; Charleton, Debbie

Researchers have identified the Web as a searchers first port of call for locating information. Search Engine Marketing (SEM) strategies have been noted as a key consideration when developing, maintaining and managing Websites. A study presented here of SEM practices of Irish small to medium enterprises (SMEs) reveals they plan to spend more resources on SEM in the future. Most firms utilize an informal SEM strategy, where Website optimization is perceived most effective in attracting traffic. Respondents cite the use of ‘keywords in title and description tags’ as the most used SEM technique, followed by the use of ‘keywords throughout the whole Website’; while ‘Pay for Placement’ was most widely used Paid Search technique. In concurrence with the literature, measuring SEM performance remains a significant challenge with many firms unsure if they measure it effectively. An encouraging finding is that Irish SMEs adopt a positive ethical posture when undertaking SEM.

Determination of precursor sites for pitting corrosion of polycrystalline titanium by using different techniques

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

Garfias-Mesias, L.F.; Alodan, M.; James, P.I.

1998-06-01

Scanning electrochemical microscopy (SECM) in ferrocyanide and bromide solutions was used to locate active sites (pitting precursors) on polycrystalline Ti where oxidation of Br{sup {minus}} and Fe(CN){sub 6}{sup 4{minus}} was possible. Analysis of the electrochemically active sites was done by using electron microscopy (SEM), energy dispersive X-ray analysis (EDX), atomic force microscopy (AFM), and in situ confocal laser scanning microscopy (CLSM). In most cases, the active sites were found to be associated with particles (inclusions) which contained mainly Al and Si; however, some other areas not associated with particles were also found to be active. Although the size of themore » inclusions was normally smaller than 20 {micro}m, as revealed by SEM and AFM imaging, in some cases larger particles were also found. Pitting corrosion tests in bromide solution at potentials above 1.5 V{sub SCE} followed by EDX analysis inside the pits and in situ CLSM observation, confirmed that most of the localized attack started in the areas where particles had been located.« less

Radiation grafting of various water-soluble monomers on ultra-high molecular weight polyethylene powder. Part II: Thermal, FTIR and morphological characterisation

NASA Astrophysics Data System (ADS)

Aydınlı, Bahattin; Tin c̡er, Teoman

2001-10-01

Radiation induced grafted polyacrylic acid (PAA), polymethacrylic acid (PMAA), polyacrylamide (PAAm), poly N,N-dimethyl acrylamide (PNDAAm) and poly 1-vinyl-2 pyrrolidone (PVP) on ultra-high molecular weight polyethylene (UHMWPE) were characterised by DSC, FTIR and SEM analysis. While the effect of irradiation on pure UHMWPE was found to increase crystallinity and cause higher enthalpy of crystallisation, grafted UHMWPE powders showed lower crystallinity and enthalpy of crystallisation. In all grafted UHMWPE there existed secondary transitions corresponding to grafting polymers in the first run of DSC above 60°C and they became clearer at a higher grafting level. In the second run of DSC some Tg values appeared to shift to higher temperatures while some were not detected. FTIR analysis indicated the presence of water-soluble polymers in the grafted UHMWPE. The characteristic peaks of water-soluble polymers became sharper in the grafted UHMWPE. SEM analysis revealed that the grafting occurs both on fiber and microparticles of UHMWPE while flowing characteristic of powder is retained.

Analysis of particulates on tape lift samples

NASA Astrophysics Data System (ADS)

Moision, Robert M.; Chaney, John A.; Panetta, Chris J.; Liu, De-Ling

2014-09-01

Particle counts on tape lift samples taken from a hardware surface exceeded threshold requirements in six successive tests despite repeated cleaning of the surface. Subsequent analysis of the particle size distributions of the failed tests revealed that the handling and processing of the tape lift samples may have played a role in the test failures. In order to explore plausible causes for the observed size distribution anomalies, scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDX), and time-of-flight secondary ion mass spectrometry (ToF-SIMS) were employed to perform chemical analysis on collected particulates. SEM/EDX identified Na and S containing particles on the hardware samples in a size range identified as being responsible for the test failures. ToF-SIMS was employed to further examine the Na and S containing particulates and identified the molecular signature of sodium alkylbenzene sulfonates, a common surfactant used in industrial detergent. The root cause investigation suggests that the tape lift test failures originated from detergent residue left behind on the glass slides used to mount and transport the tape following sampling and not from the hardware surface.

Synthesis and characterization of FeSe1-xTex (x=0, 0.5, 1) superconductors

NASA Astrophysics Data System (ADS)

Zargar, Rayees A.; Hafiz, A. K.; Awana, V. P. S.

2015-08-01

In this study, FeTe1-xSex (x=0,0.5,1) samples were prepared by conventional solid state reaction method and investigated by powder XRD, SEM, Raman and resistivity measurement techniques to reveal the effect of tellurium (Te) substitution in FeSe matrix. Rietveld analysis was performed on room temperature recorded, X-ray diffraction (XRD) patterns of pure FeSe, FeTe and FeSe0.5Te0.5 which shows that all the compounds are crystallized in a tetragonal structure. SEM images show the dense surface morphology. Raman spectra recorded in the range from 100 to 700 cm-1 at ambient temperature has been interpreted by P4/nmm space group of the lattice. The variation in intensity and shift in peak positions of some phonon modes has been discussed on the basis of variation in crystalline field effect by substituting Te in FeSe lattice. The resistivity versus temperature curves reveals that FeSe becomes superconductor at 7 K and FeSe0.5Te0.5 shows superconductivity below 14 K while FeTe is non-superconducting compound.

Scalable synthesis of aligned carbon nanotubes bundles using green natural precursor: neem oil

NASA Astrophysics Data System (ADS)

Kumar, Rajesh; Tiwari, Radhey Shyam; Srivastava, Onkar Nath

2011-12-01

Practical application of aligned carbon nanotubes (ACNTs) would have to be determined by a matter of its economical and large-scale preparation. In this study, neem oil (also named Margoaa oil, extracted from the seeds of the neem-- Azadirachta indica) was used as carbon source to fabricate the bundles of ACNTs. ACNTs have been synthesized by spray pyrolysis of neem oil and ferrocene mixture at 825°C. The major components of neem oil are hydrocarbon with less amount of oxygen, which provided the precursor species in spray pyrolysis growth of CNTs. The bundles of ACNTs have been grown directly inside the quartz tube. The as-grown ACNTs have been characterized through Raman spectroscopy, scanning and transmission electron microscopic (SEM/TEM) techniques. SEM images reveal that the bundles of ACNTs are densely packed and are of several microns in length. High-resolution TEM analysis reveals these nanotubes to be multi-walled CNTs. These multi-walled CNTs were found to have inner diameter between 15 and 30 nm. It was found that present technique gives high yield with high density of bundles of ACNTs.

Scalable synthesis of aligned carbon nanotubes bundles using green natural precursor: neem oil.

PubMed

Kumar, Rajesh; Tiwari, Radhey Shyam; Srivastava, Onkar Nath

2011-01-18

Practical application of aligned carbon nanotubes (ACNTs) would have to be determined by a matter of its economical and large-scale preparation. In this study, neem oil (also named Margoaa oil, extracted from the seeds of the neem--Azadirachta indica) was used as carbon source to fabricate the bundles of ACNTs. ACNTs have been synthesized by spray pyrolysis of neem oil and ferrocene mixture at 825°C. The major components of neem oil are hydrocarbon with less amount of oxygen, which provided the precursor species in spray pyrolysis growth of CNTs. The bundles of ACNTs have been grown directly inside the quartz tube. The as-grown ACNTs have been characterized through Raman spectroscopy, scanning and transmission electron microscopic (SEM/TEM) techniques. SEM images reveal that the bundles of ACNTs are densely packed and are of several microns in length. High-resolution TEM analysis reveals these nanotubes to be multi-walled CNTs. These multi-walled CNTs were found to have inner diameter between 15 and 30 nm. It was found that present technique gives high yield with high density of bundles of ACNTs.

Sexually explicit media on the internet: a content analysis of sexual behaviors, risk, and media characteristics in gay male adult videos.

PubMed

Downing, Martin J; Schrimshaw, Eric W; Antebi, Nadav; Siegel, Karolynn

2014-05-01

Recent research suggests that viewing sexually explicit media (SEM), i.e., adult videos, may influence sexual risk taking among men who have sex with men. Despite this evidence, very little is known about the content of gay male SEM on the Internet, including the prevalence of sexual risk behaviors and their relation to video- and performer-characteristics, viewing frequency, and favorability. The current study content analyzed 302 sexually explicit videos featuring male same-sex performers that were posted to five highly trafficked adult-oriented websites. Findings revealed that gay male SEM on the Internet features a variety of conventional and nonconventional sexual behaviors. There was a substantial prevalence of unprotected anal intercourse (UAI) (34 %) and was virtually the same as the prevalence of anal sex with a condom (36 %). The presence of UAI was not associated with video length, amateur production, number of video views, favorability, or website source. However, the presence of other potentially high-risk behaviors (e.g., ejaculation in the mouth, and ejaculation on/in/rubbed into the anus) was associated with longer videos, more views, and group sex videos (three or more performers). The findings of high levels of sexual risk behavior and the fact that there was virtually no difference in the prevalence of anal sex with and without a condom in gay male SEM have important implications for HIV prevention efforts, future research on the role of SEM on sexual risk taking, and public health policy.

Quantifying Golgi structure using EM: combining volume-SEM and stereology for higher throughput.

PubMed

Ferguson, Sophie; Steyer, Anna M; Mayhew, Terry M; Schwab, Yannick; Lucocq, John Milton

2017-06-01

Investigating organelles such as the Golgi complex depends increasingly on high-throughput quantitative morphological analyses from multiple experimental or genetic conditions. Light microscopy (LM) has been an effective tool for screening but fails to reveal fine details of Golgi structures such as vesicles, tubules and cisternae. Electron microscopy (EM) has sufficient resolution but traditional transmission EM (TEM) methods are slow and inefficient. Newer volume scanning EM (volume-SEM) methods now have the potential to speed up 3D analysis by automated sectioning and imaging. However, they produce large arrays of sections and/or images, which require labour-intensive 3D reconstruction for quantitation on limited cell numbers. Here, we show that the information storage, digital waste and workload involved in using volume-SEM can be reduced substantially using sampling-based stereology. Using the Golgi as an example, we describe how Golgi populations can be sensed quantitatively using single random slices and how accurate quantitative structural data on Golgi organelles of individual cells can be obtained using only 5-10 sections/images taken from a volume-SEM series (thereby sensing population parameters and cell-cell variability). The approach will be useful in techniques such as correlative LM and EM (CLEM) where small samples of cells are treated and where there may be variable responses. For Golgi study, we outline a series of stereological estimators that are suited to these analyses and suggest workflows, which have the potential to enhance the speed and relevance of data acquisition in volume-SEM.

A Detailed Analysis of Visible Defects Formed in Commercial Silicon Thin-Film Modules During Outdoor Exposure

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

Gerber, Andreas; Johnston, Steve; Olivera-Pimentel, Guillermo

We analyzed defects in silicon thin-film tandem (a-Si:H/..mu..c-Si:H) modules from an outdoor installation in India. The inspection of several affected modules reveals that most of the defects -- which optically appear as bright spots -- were formed primarily nearby the separation and series connection laser lines. Cross-sectional SEM analysis reveals that the bright spots emerge due to electrical isolation, caused by a delamination of the cell from the front TCO in the affected area. In addition, the morphology of the a-Si:H top cell differs in the delaminated area compared to the surrounding unaffected area. We propose that these effects aremore » potentially caused by an explosive and thermally triggered liberation of hydrogen from the a-Si:H layer. Electrical and thermal measurements reveal that these defects can impact the cell performance significantly.« less

Hydrogen Gas Sensing Characteristics of Nanostructured NiO Thin Films Synthesized by SILAR Method

NASA Astrophysics Data System (ADS)

Karaduman, Irmak; Çorlu, Tugba; Yıldırım, M. Ali; Ateş, Aytunç; Acar, Selim

2017-07-01

Nanostructured NiO thin films have been synthesized by a facile, low-cost successive ionic layer adsorption and reaction (SILAR) method, and the effects of the film thickness on their hydrogen gas sensing properties investigated. The samples were characterized by scanning electron microscopy (SEM), x-ray diffraction (XRD) analysis, and energy-dispersive x-ray analysis. The XRD results revealed that the crystallinity improved with increasing thickness, exhibiting polycrystalline structure. SEM studies showed that all the films covered the glass substrate well. According to optical absorption measurements, the optical bandgap decreased with increasing film thickness. The gas sensing properties of the nanostructured NiO thin films were studied as a function of operating temperature and gas concentration. The samples showed good sensing performance of H2 gas with high response. The maximum response was 75% at operating temperature of 200°C for hydrogen gas concentration of 40 ppm. These results demonstrate that nanostructured NiO thin films synthesized by the SILAR method have potential for application in hydrogen detection.

Cigarette smoke affects bonding to dentin.

PubMed

Almeida e Silva, Junio S; de Araujo, Edson Medeiro; Araujo, Elito

2010-01-01

This in vitro study evaluated the microtensile bond strength (muTBS) of composite resin bonded to dentin that had been contaminated by cigarette smoke. Ten extracted unerupted human third molars were used: Six molars were prepared for muTBS testing, while the other four molars were assigned to pre- and post-etching scanning electronic microscopy (SEM) analysis. The 20 specimens obtained from the 10 coronal portions were distributed into two experimental groups so that each tooth served as its own control. Group 1 underwent a daily toothbrushing simulation and exposure to a smoking simulation chamber, while Group 2 received only a daily simulated toothbrushing. Student's t-test demonstrated that Group 1 samples demonstrated significantly lower bond strength (49.58 MPa) than Group 2 samples (58.48 MPa). Pre and postetching SEM analysis revealed the presence of contaminants on the dentinal surfaces of the Group 1 specimens. It was concluded that contamination by cigarette smoke decreases the bond strength between dentin and composite resin.

Microbial population Diversity of indigenous acidophilic bacteria for recovering the valuable resources

NASA Astrophysics Data System (ADS)

Kim, B.; Cho, K.; Lee, D.; Choi, N.; Park, C.

2011-12-01

A taxon- or group-specific PCR primer serves as a valuable tool for studying the bioleaching mechanisms of a particular group of microorganisms. Especially for an uncultured (or very difficult to isolate from their environments) group of microorganisms, the group-specific PCR primer is essential for the investigation of distribution patterns and the estimation of genetic diversity of the target microorganisms. This study investigated the Biodiversity through molecular biology method using the three different indigenous acidophilic bacteria collected from acid mine drainage in Go-seong and Yeon-hwa, Korea and acidic hot spring in Hatchnobaru, Japan. We performed the optical analysis (phase-contrast microscope and SEM), base sequencing. In the phase-contrast microscope(X 4,000) and SEM analysis, the rod-shaped bacteria with 1μm in length were observed. The results of base sequencing using EzTaxon server data revealed Acidithiobacillus ferrooxidans (Go-seong - 97.79%, Yeon-hwa - 97.90% and Hatchnobaru - 97.97%)

Control of the shape and size of iron oxide (α-Fe2O3) nanoparticles synthesized through the chemical precipitation method

NASA Astrophysics Data System (ADS)

Lassoued, Abdelmajid; Dkhil, Brahim; Gadri, Abdellatif; Ammar, Salah

Hematite (α-Fe2O3) nanoparticles were synthesized via a simple chemical precipitation method. The impact of varying the concentration of precursor on the crystalline phase, size and morphology of α-Fe2O3 products was explored. The characteristic of the synthesized hematite nanoparticles were evaluated by X-ray diffraction (XRD), Transmission Electron Microscopy (TEM), Scanning Electron Microscopy (SEM), Fourier Transform Infra-Red (FT-IR) spectroscopy, Raman spectroscopy, Differential Thermal Analysis (DTA), Thermo Gravimetric Analysis (TGA), Ultraviolet-Visible (UV-Vis) analysis and Photoluminescence (PL). XRD data revealed a rhombohedral (hexagonal) structure with the space group R-3c in all samples. Uniform spherical like morphology was confirmed by TEM and SEM. The result revealed that the particle sizes were varied between 21 and 82 nm and that the increase in precursor concentration (FeCl3, 6H2O) is accompanied by an increase in the particle size of 21 nm for pure α-Fe2O3 synthesized with [Fe3+] = 0.05 M at 82 nm for pure α-Fe2O3 synthesized with [Fe3+] = 0.4 M. FT-IR confirms the phase purity of the nanoparticles synthesized. The Raman spectroscopy was used not only to prove that we have synthesized pure hematite but also to identify their phonon modes. The thermal behavior of compound was studied by using TGA/DTA results: The TGA showed three mass losses, whereas DTA resulted in three endothermic peaks. Besides, the optical investigation revealed that samples have an optical gap of about 2.1 eV and that this value varies as a function of the precursor concentration.

Correlated Raman micro-spectroscopy and scanning electron microscopy analyses of flame retardants in environmental samples: a micro-analytical tool for probing chemical composition, origin and spatial distribution.

PubMed

Ghosal, Sutapa; Wagner, Jeff

2013-07-07

We present correlated application of two micro-analytical techniques: scanning electron microscopy/energy dispersive X-ray spectroscopy (SEM/EDS) and Raman micro-spectroscopy (RMS) for the non-invasive characterization and molecular identification of flame retardants (FRs) in environmental dusts and consumer products. The SEM/EDS-RMS technique offers correlated, morphological, molecular, spatial distribution and semi-quantitative elemental concentration information at the individual particle level with micrometer spatial resolution and minimal sample preparation. The presented methodology uses SEM/EDS analyses for rapid detection of particles containing FR specific elements as potential indicators of FR presence in a sample followed by correlated RMS analyses of the same particles for characterization of the FR sub-regions and surrounding matrices. The spatially resolved characterization enabled by this approach provides insights into the distributional heterogeneity as well as potential transfer and exposure mechanisms for FRs in the environment that is typically not available through traditional FR analysis. We have used this methodology to reveal a heterogeneous distribution of highly concentrated deca-BDE particles in environmental dust, sometimes in association with identifiable consumer materials. The observed coexistence of deca-BDE with consumer material in dust is strongly indicative of its release into the environment via weathering/abrasion of consumer products. Ingestion of such enriched FR particles in dust represents a potential for instantaneous exposure to high FR concentrations. Therefore, correlated SEM/RMS analysis offers a novel investigative tool for addressing an area of important environmental concern.

Broadly Applicable Nanowafer Drug Delivery System for Treating Eye Injuries

DTIC Science & Technology

2014-09-01

the drug molecular transport into the cornea. Intravital laser confocal imaging of the live mouse cornea demonstrating the presence of drug in the...vivo drug release in the mouse cornea by laser confocal fluorescence imaging study revealed that the nanowafers upon instillation on mouse eye were...C) 500nm; (D) 1µm; (E) 1.5µm; and (F) 3µm A B C D E F microscopy (SEM) for the feature integrity and uniformity. The SEM images revealed the presence

In situ micro-compression testing of He2+ ion irradiated titanium aluminide

NASA Astrophysics Data System (ADS)

Wei, Tao; Xu, Alan; Zhu, Hanliang; Ionescu, Mihail; Bhattacharyya, Dhriti

2017-10-01

A titanium aluminide (TiAl) alloy 45XD has been irradiated by a He ion beam with an energy of 5 MeV on a tandem accelerator at the Australian Nuclear Science and Technology Organization (ANSTO). The total fluence of He ions was 5 × 1017 ion cm-2. A 17 μm uniform damage region from the material surface with a helium concentration of about 5000 appm was achieved by using an energy degrading wheel in front of the TiAl target. The micro-size test specimens from the damage layer were fabricated using a focused ion beam & scanning electron microscope (FIB-SEM) system. The in situ SEM micromechanical compressive testing was carried out inside an SEM and the results indicated irradiation embrittlement in the helium affected region. Electron back scatter diffraction (EBSD) analysis has been applied to reveal the orientation of the lamellae in the TiAl specimens, and used to understand the deformation processes in the sample. The irradiation damage of gallium ion beam from FIB on the surface of TiAl sample was also investigated.

Axial displacement of external and internal implant-abutment connection evaluated by linear mixed model analysis.

PubMed

Seol, Hyon-Woo; Heo, Seong-Joo; Koak, Jai-Young; Kim, Seong-Kyun; Kim, Shin-Koo

2015-01-01

To analyze the axial displacement of external and internal implant-abutment connection after cyclic loading. Three groups of external abutments (Ext group), an internal tapered one-piece-type abutment (Int-1 group), and an internal tapered two-piece-type abutment (Int-2 group) were prepared. Cyclic loading was applied to implant-abutment assemblies at 150 N with a frequency of 3 Hz. The amount of axial displacement, the Periotest values (PTVs), and the removal torque values(RTVs) were measured. Both a repeated measures analysis of variance and pattern analysis based on the linear mixed model were used for statistical analysis. Scanning electron microscopy (SEM) was used to evaluate the surface of the implant-abutment connection. The mean axial displacements after 1,000,000 cycles were 0.6 μm in the Ext group, 3.7 μm in the Int-1 group, and 9.0 μm in the Int-2 group. Pattern analysis revealed a breakpoint at 171 cycles. The Ext group showed no declining pattern, and the Int-1 group showed no declining pattern after the breakpoint (171 cycles). However, the Int-2 group experienced continuous axial displacement. After cyclic loading, the PTV decreased in the Int-2 group, and the RTV decreased in all groups. SEM imaging revealed surface wear in all groups. Axial displacement and surface wear occurred in all groups. The PTVs remained stable, but the RTVs decreased after cyclic loading. Based on linear mixed model analysis, the Ext and Int-1 groups' axial displacements plateaued after little cyclic loading. The Int-2 group's rate of axial displacement slowed after 100,000 cycles.

Structural and optical properties of ZnO nanorods synthesized via template free approach

NASA Astrophysics Data System (ADS)

Kajal, Priyanka; D, Pooja; Jaggi, Neena

2016-06-01

In this paper, we report a novel method for synthesis of semiconducting ZnO nanorods using Zinc acetate dehydrate precursor in a methanol—de-ionized (1:5) mixture via template free approach. Scanning electron microscope (SEM) and transmission electron microscope (TEM) images of as synthesized nanorods revealed hexagonal symmetry of rods, whereas x-ray diffraction (XRD) analysis for structure and phase has shown high crystallinity with wurtzite crystal structure. The structural characterization by FT-IR analysis revealed presence of various groups on as synthesized ZnO nanorods, whereas the UV-Vis analysis has shown a blue shift in the absorption spectra as compared to bulk ZnO due to quantum confinement of charge carriers. Photoluminescence (PL) spectroscopy study has also been performed revealing a good degree of phosphorescence in the ZnO nanorods. Further, thermo gravimetric analysis (TGA) revealed that as synthesized nanorods by present method are highly stable at high temperature (1000 °C). This study provides an alternative, less expensive and a very simple method for the fabrication of ZnO nanorods in abundance, which can be further used for various sensing applications, in particular, gas sensing.

Mechanical and interfacial characterization of laser welded Co-Cr alloy with different joint configurations

PubMed Central

Kokolis, John; Chakmakchi, Makdad; Theocharopoulos, Antonios; Prombonas, Anthony

2015-01-01

PURPOSE The mechanical and interfacial characterization of laser welded Co-Cr alloy with two different joint designs. MATERIALS AND METHODS Dumbbell cast specimens (n=30) were divided into 3 groups (R, I, K, n=10). Group R consisted of intact specimens, group I of specimens sectioned with a straight cut, and group K of specimens with a 45° bevel made at the one welding edge. The microstructure and the elemental distributions of alloy and welding regions were examined by an SEM/EDX analysis and then specimens were loaded in tension up to fracture. The tensile strength (TS) and elongation (ε) were determined and statistically compared among groups employing 1-way ANOVA, SNK multiple comparison test (α=.05) and Weibull analysis where Weibull modulus m and characteristic strength σο were identified. Fractured surfaces were imaged by a SEM. RESULTS SEM/EDX analysis showed that cast alloy consists of two phases with differences in mean atomic number contrast, while no mean atomic number was identified for welded regions. EDX analysis revealed an increased Cr and Mo content at the alloy-joint interface. All mechanical properties of group I (TS, ε, m and σο) were found inferior to R while group K showed intermediated values without significant differences to R and I, apart from elongation with group R. The fractured surfaces of all groups showed extensive dendritic pattern although with a finer structure in the case of welded groups. CONCLUSION The K shape joint configuration should be preferred over the I, as it demonstrates improved mechanical strength and survival probability. PMID:25722836

Scanning electron microscopy of clays and clay minerals

USGS Publications Warehouse

Bohor, B.F.; Hughes, R.E.

1971-01-01

The scanning electron microscope (SEM) proves to be ideally suited for studying the configuration, texture, and fabric of clay samples. Growth mechanics of crystalline units—interpenetration and interlocking of crystallites, crystal habits, twinning, helical growth, and topotaxis—also are uniquely revealed by the SEM.Authigenic kaolins make up the bulk of the examples because their larger crystallite size, better crystallinity, and open texture make them more suited to examination by the SEM than most other clay mineral types.

RuO2/Activated Carbon Composite Electrode Prepared by Modified Colloidal Procedure and Thermal Decomposition Method

NASA Astrophysics Data System (ADS)

Li, Xiang; Zheng, Feng; Gan, Weiping; Luo, Xun

2016-01-01

RuO2/activated carbon (AC) composite electrode was prepared by a modified colloidal procedure and a thermal decomposition method. The precursor for RuO2/AC was coated on tantalum sheet and annealed at 150°C to 190°C for 3 h to develop thin-film electrode. The microstructure and morphology of the RuO2/AC film were characterized by thermogravimetric analysis (TGA), x-ray diffraction (XRD) analysis, and scanning electron microscopy (SEM). The TGA results showed the maximum loss of RuO2/AC composite film at 410°C, with residual RuO2 of 23.17 wt.%. The amorphous phase structure of the composite was verified by XRD analysis. SEM analysis revealed that fine RuO2 particles were dispersed in an activated carbon matrix after annealing. The electrochemical properties of RuO2/AC electrode were examined by cycling voltammetry, galvanostatic charge-discharge, and cyclic behavior measurements. The specific capacitance of RuO2/AC electrode reached 245 F g-1. The cyclic behavior of RuO2/AC electrode was stable. Optimal annealing was achieved at 170°C for 3 h.

Flame retardancy and thermal behavior of intumescent flame-retardant EVA composites with an efficient triazine-based charring agent

NASA Astrophysics Data System (ADS)

Xu, Bo; Ma, Wen; Wu, Xiao; Qian, Lijun; Jiang, Shan

2018-04-01

Intumescent flame retardant (IFR) EVA composites were prepared based on a hyperbranched triazine charring-foaming agent (HTCFA) and ammonium polyphosphate (APP). The synergistic effect of HTCFA and APP on the flame retardancy and thermal behavior of the composites were investigated through flammability tests, cone calorimeter measurements, thermogravimetric analysis (TGA) including evolved gas analysis (TG-IR) and residue analysis (Fourier transform infrared (FTIR), laser Raman spectroscopy (LRS), x-ray Photoelectron Spectroscopy (XPS) and scanning electron microscopy (SEM)). The flammability test results showed HTCFA/APP (1/3) system presented the best synergistic effect in flame-retardant EVA composites with the highest LOI value and UL-94 V-0 rating. As for cone calorimeter results, IFR changed the combustion behavior of EVA and resulted in remarkable decrease of flammability and smoke product. TGA results showed the synergistic effect between APP and HTCFA could strengthen the char-forming ability of composites. TG-IR results indicated the melt viscosities and gas release with increasing temperature were well-correlated for EVA/IFR composite. The residue analysis results from SEM, LRS, FT-IR and XPS revealed IFR promoted forming more compact graphitic char layer, connected by rich P–O–C and P–N structures.

Balantioides coli: morphological and ultrastructural characteristics of pig and non-human primate isolates.

PubMed

Barbosa, Alynne da Silva; Barbosa, Helene Santos; Souza, Sandra Maria de Oliveira; Dib, Laís Verdan; Uchôa, Claudia Maria Antunes; Bastos, Otilio Machado Pereira; Amendoeira, Maria Regina Reis

2018-06-26

Balantioides coli is a ciliated protozoon that inhabits the intestine of pigs, non-human primates and humans. Light microscopy studies have described over 50 species of the genus Balantioides but their validity is in doubt. Due to the limited information about this genus, this study is aimed to identify morphological characteristics of Balantioides coli isolated using fluorescence microscopy and both scanning (SEM) and transmission electron microscopy (TEM). Trophozoites isolated from the feces of pig and macaque were washed and subjected to centrifugation. These cells were fixed with paraformaldehyde for immunofluorescence. Other aliquots of these trophozoites were fixed with glutaraldehyde, post fixed with osmium tetroxide and processed for SEM and TEM. Immunofluorescence studies revealed microtubules with a longitudinal distribution to the main axis of the parasite and in the constitution of cilia. SEM demonstrated a high concentration of cilia covering the oral apparatus and a poor presence of such structures in cytopyge. TEM revealed in the plasma membrane, several associated structures were observed to delineate the cellular cortex and mucocysts. The cytoskeleton of the oral region was observed in detail and had an organization pattern consisting of microtubules, which formed files and nematodesmal networks. Organelles such as hydrogenosomes like and peroxisomes were observed close to the cortex. Macronuclei were observed, but structures that were consistent with micronuclei were not identified. Ultrastructural morphological analysis of isolates confirms its similarity to Balantioides coli. In this study were identified structures that had not yet been described, such as hydrogenosomes like and cytoskeletal structures.

Microstructural and optical properties of Mn doped NiO nanostructures synthesized via sol-gel method

NASA Astrophysics Data System (ADS)

Shah, Shamim H.; Khan, Wasi; Naseem, Swaleha; Husain, Shahid; Nadeem, M.

2018-04-01

Undoped and Mn(0, 5%, 10% and 15%) doped NiO nanostructures were synthesized by sol-gel method. Structure, morphology and optical properties were investigated through XRD, FTIR, SEM/EDS and UV-visible absorption spectroscopy techniques. XRD data analysis reveals the single phase nature with cubic crystal symmetry of the samples and the average crystallite size decreases with the doping of Mn ions upto 10%. FTIR spectra further confirmed the purity and composition of the synthesized samples. The non-spherical shape of the nanostructures was observed from SEM micrographs and gain size of the nanostructures reduces with Mn doping in NiO, whereas agglomeration increases in doped sample. Optical band gap was estimated using Tauc'srelation and found to increase on incorporation of Mn upto 10% in host lattice and then decreases for further doping.

Synthesis of nanocrystalline α-Fe2O3 by using thermal oxidation of Fe Films

NASA Astrophysics Data System (ADS)

Fortas, G.; Saidoun, I.; Abboud, H.; Gabouze, N.; Haine, N.; Manseri, A.; Zergoug, M.; Menari, H.; Sam, S.; Cheraga, H.; Bozetine, I.

2018-03-01

α-Fe2O3 hematite films were prepared by thermal oxidation from Fe films electroplated on silicon. Electrodeposition of Fe thin films was carried out from a sulfate bath containing an ammonium chloride complexing agent. The electrochemical study was performed by cyclic voltammetry. The SEM analysis of the films obtained at a -1.3 V constant polarization shows dendritic grains in the form of islet. The DRX spectra exhibit characteristic iron peaks according to the face centered cubic (Fcc) structure. These samples were annealed. At a temperature of 650 ° C, a single iron oxide phase was well formed, with the hematite structure. The SEM photos show a well-assembled columnar structure with formation of nanowires at the surface of the deposit. The absorbance spectra reveal an absorption features in the ultraviolet range

Atomic force microscopy imaging of fragments from the Martian meteorite ALH84001

NASA Technical Reports Server (NTRS)

Steele, A.; Goddard, D.; Beech, I. B.; Tapper, R. C.; Stapleton, D.; Smith, J. R.

1998-01-01

A combination of scanning electron microscopy (SEM) and environmental scanning electron microscopy (ESEM) techniques, as well as atomic force microscopy (AFM) methods has been used to study fragments of the Martian meteorite ALH84001. Images of the same areas on the meteorite were obtained prior to and following gold/palladium coating by mapping the surface of the fragment using ESEM coupled with energy-dispersive X-ray analysis. Viewing of the fragments demonstrated the presence of structures, previously described as nanofossils by McKay et al. (Search for past life on Mars--possible relic biogenic activity in martian meteorite ALH84001. Science, 1996, pp. 924-930) of NASA who used SEM imaging of gold-coated meteorite samples. Careful imaging of the fragments revealed that the observed structures were not an artefact introduced by the coating procedure.

Deformation and failure mechanism of secondary cell wall in Spruce late wood

NASA Astrophysics Data System (ADS)

Adusumalli, Ramesh-Babu; Raghavan, Rejin; Ghisleni, Rudy; Zimmermann, Tanja; Michler, Johann

2010-08-01

The deformation and failure of the secondary cell wall of Spruce wood was studied by in-situ SEM compression of micropillars machined by the focused ion beam technique. The cell wall exhibited yield strength values of approximately 160 MPa and large scale plasticity. High resolution SEM imaging post compression revealed bulging of the pillars followed by shear failure. With additional aid of cross-sectional analysis of the micropillars post compression, a model for deformation and failure mechanism of the cell wall has been proposed. The cell wall consists of oriented cellulose microfibrils with high aspect ratio embedded in a hemicellulose-lignin matrix. The deformation of the secondary wall occurs by asymmetric out of plane bulging because of buckling of the microfibrils. Failure of the cell wall following the deformation occurs by the formation of a shear or kink band.

Synthesis and toxicity test of magnetic nanoparticle via biocompatible microemulsion system as template for application in targeted drug delivery

NASA Astrophysics Data System (ADS)

Kader, Razinah Abdul; Rose, Laili Che; Suhaimi, Hamdan; Manickam, Mariessa Soosai

2017-09-01

This work reports the preparation of magnetic nanoparticles (FeNPs) using biocompatible W/O microemulsion for biomedical applications. W/O microemulsion was formed using decane as oil phase, water, tween 80 as non-ionic surfactant and hexanol as organic solvent. The synthesized FeNPs were characterised by using Fourier Transform Infrared Resonance Spectroscopy (FTIR), Scanning Electron Microscopy (SEM) and X-Ray Diffraction (XRD). The FTIR showed that Fe-O bond exist on 581cm-1 having strong magnetic strength whereas SEM showed the morphology surface of magnetic nanoparticles (FeNPs). Furthermore, analysis of XRD pattern magnetic nanoparticles (FeNPs) reveals a cubic iron oxide phase with good crystallize structure. Furthermore, toxicity test on human liver cells proved that it is 70% safe on human and proved to be a safety nanomedicine.

Facile and Chemically Pure Preparation of YVO4:Eu3+ Colloid with Novel Nanostructure via Laser Ablation in Water

PubMed Central

Wang, Haohao; Odawara, Osamu; Wada, Hiroyuki

2016-01-01

A YVO4:Eu3+ colloid with an interesting nanostructure was formed by pulsed laser ablation in deionized water without any additives or surfactants. Analyses of particle morphology, composition and optical properties were accomplished by SEM, TEM, EDS PL and UV-vis. Ovoid-like particles formed by the agglomeration of numerous nanocrystals were observed by SEM and TEM, while EDS with area-mode analysis revealed that the content of dopant ion was well retained within the nanoparticles. In addition, the formation mechanism is deduced and discussed for the first time in this research. The findings of this study could provide new insights into the understanding of laser-induced oxide materials and offer an opportunity for other research groups to pursue red emitting nanophosphors with outstandingly purity. PMID:26842419

Copper Oxide Nanograss for Efficient and Stable Photoelectrochemical Hydrogen Production by Water Splitting

NASA Astrophysics Data System (ADS)

Borkar, Rajnikant; Dahake, Rashmi; Rayalu, Sadhana; Bansiwal, Amit

2018-03-01

A biphasic copper oxide thin film of grass-like appendage morphology is synthesized by two-step electro-deposition method and later investigated for photoelectrochemical (PEC) water splitting for hydrogen production. Further, the thin film was characterized by UV-Visible spectroscopy, x-ray diffraction (XRD), Scanning electron microscopy (SEM) and PEC techniques. The XRD analysis confirms formation of biphasic copper oxide phases, and SEM reveals high surface area grass appendage-like morphology. These grass appendage structures exhibit a high cathodic photocurrent of - 1.44 mAcm-2 at an applied bias of - 0.7 (versus Ag/AgCl) resulting in incident to photon current efficiency (IPCE) of ˜ 10% at 400 nm. The improved light harvesting and charge transport properties of grass appendage structured biphasic copper oxides makes it a potential candidate for PEC water splitting for hydrogen production.

Electrical properties of palladium-doped CaCu3Ti4O12 ceramics

NASA Astrophysics Data System (ADS)

Singh, Arashdeep; Md Mursalin, Sk.; Rana, P.; Sen, Shrabanee

2015-09-01

The effect of doping palladium (Pd) at the Cu site of CaCu3Ti4O12 powders (CCPTO) synthesized by sol-gel technique on electrical properties was studied. XRD analysis revealed the formation of CCTO and CCPTO ceramics with some minor quantities of impurities. SEM micrographs revealed that the grain size decreased with Pd doping. TEM micrographs of CCPTO powder showed the formation of irregular-shaped particles of ~40 nm. The dielectric constant and dielectric loss showed a significant enhancement with Pd doping. A significant decrease in grain-boundary resistance with Pd doping was ascertained by impedance spectroscopy study.

The effects of sexually explicit material use on romantic relationship dynamics

PubMed Central

Minarcik, Jenny; Wetterneck, Chad T.; Short, MARY B.

2016-01-01

Background and aims Pornography use has become increasingly common. Studies have shown that individuals who use sexually explicit materials (SEMs) report negative effects (Schneider, 2000b). However, Bridges (2008b) found that couples who use SEM together have higher relationship satisfaction than those who use SEM independently. A further investigation into various types of SEM use in relationships may highlight how SEM is related to various areas of couple satisfaction. Thus, the purpose of the current study is to examine the impact of SEM use related to different relationship dynamics. Methods The current study included a college and Internet sample of 296 participants divided into groups based upon the SEM use in relationships (i.e., SEM alone, SEM use with partner, and no SEM use). Results There were significant differences between groups in relationship satisfaction [F(2, 252) = 3.69, p = .026], intimacy [F(2, 252) = 7.95, p = <.001], and commitment [F(2, 252) = 5.30, p = .006]. Post-hoc analyses revealed additional differences in relationship satisfaction [t(174) = 2.13, p = .035] and intimacy [t(174) = 2.76, p = .006] based on the frequency of SEM use. Discussion Further exploration of the SEM use function in couples will provide greater understanding of its role in romantic relationships. PMID:27784182

Eu2+,Dy3+ codoped SrAl2O4 nanocrystalline phosphor for latent fingerprint detection in forensic applications

NASA Astrophysics Data System (ADS)

Sharma, Vishal; Das, Amrita; Kumar, Vinay

2016-01-01

In this work, europium and dysprosium doped strontium aluminate (SrAl2O4:Eu2+,Dy3+) nanophosphor is synthesized and its novel application for the detection of latent fingerprints on various contact surfaces is reported. The SrAl2O4:Eu2+,Dy3+ is synthesized using a combustion method and shows long-lasting afterglow luminescence. The powder particles are characterized using field emission scanning electron microscopy (FE-SEM), SEM-energy dispersive x-ray analysis, x-ray diffraction and photoluminescence spectrophotometry. The FE-SEM image analysis reveals that the nanoparticles are mostly 8-15 nm in size with an irregular spherical shape. This nano-structured powder was applied to fresh and aged fingerprints deposited on porous, semi-porous and non-porous contact surfaces, such as ordinary colored paper, glossy paper, glass, aluminum foil, a yellow foil chocolate wrapper, a soft drink can, a PET bottle, a compact disc and a computer mouse. The results are reproducible and show great sensitivity and high contrast in the developed fingermark regions on these surfaces. These nanophosphor particles also show a strong and long-lasting afterglow property, making them a suitable candidate for use as a fingerprint developing agent on luminescent and highly patterned surfaces. These kinds of powders have shown that they can remove the interference from background luminescence, which is not possible using ordinary luminescent fingerprinting powders.

Degradation of polyester polyurethane by a newly isolated soil bacterium, Bacillus subtilis strain MZA-75.

PubMed

Shah, Ziaullah; Krumholz, Lee; Aktas, Deniz Fulya; Hasan, Fariha; Khattak, Mutiullah; Shah, Aamer Ali

2013-11-01

A polyurethane (PU) degrading bacterial strain MZA-75 was isolated from soil through enrichment technique. The bacterium was identified through 16S rRNA gene sequencing, the phylogenetic analysis indicated the strain MZA-75 belonged to genus Bacillus having maximum similarity with Bacillus subtilis strain JBE0016. The degradation of PU films by strain MZA-75 in mineral salt medium (MSM) was analyzed by scanning electron microscopy (SEM), fourier transform infra-red spectroscopy (FT-IR) and gel permeation chromatography (GPC). SEM revealed the appearance of widespread cracks on the surface. FTIR spectrum showed decrease in ester functional group. Increase in polydispersity index was observed in GPC, which indicates chain scission as a result of microbial treatment. CO2 evolution and cell growth increased when PU was used as carbon source in MSM in Sturm test. Increase in both cell associated and extracellular esterases was observed in the presence of PU indicated by p-Nitrophenyl acetate (pNPA) hydrolysis assay. Analysis of cell free supernatant by gas chromatography-mass spectrometry (GC-MS) revealed that 1,4-butanediol and adipic acid monomers were produced. Bacillus subtilis strain MZA-75 can degrade the soft segment of polyester polyurethane, unfortunately no information about the fate of hard segment could be obtained. Growth of strain MZA-75 in the presence of these metabolites indicated mineralization of ester hydrolysis products into CO2 and H2O.

Physicochemical characterization and antitumour activity of exopolysaccharides produced by Lactobacillus casei SB27 from yak milk.

PubMed

Di, Wei; Zhang, Lanwei; Wang, Shumei; Yi, Huaxi; Han, Xue; Fan, Rongbo; Zhang, Yingchun

2017-09-01

Two high molecular weight fractions (LW1 and LW2) of exopolysaccharides (EPSs) produced by Lactobacillus casei SB27 were isolated from yak milk obtained from the Gansu Tibetan area of China. GC-MS, FTIR spectroscopy, methylation analysis and FE-SEM analysis were performed to elucidate the physicochemical characterization of these two fractions, and their in vitro antitumour activities were also evaluated. The molecular weights (Mws) of LW1 and LW2 as determined by HPGPC were 25.10 and 12.34kDa, respectively. Monosaccharide composition analysis revealed that LW1 and LW2 were mainly composed of galactose (52.4% and 57.4%, mol%) and glucose (29.1% and 22.2%, mol%), respectively. Methylation results showed that the main chain of LW1 likely involves (1→4)-linked Galp and (1→4)-linked Glcp with its side chains being (1→4,6)-linked Galp through the O-6 position connected to the backbone, whereas the main chain of LW2 likely involves (1→4)-linked Galp and (1→4)-linked Glcp with its side chains being (1→3)-Galp through the O-6 position of (1→3,6)-Galp linked to the main chain. Evaluation of the microcosmic morphology, as revealed by FE-SEM analysis of the two EPS fractions, showed a sheet-like appearance with a folded surface and a compact structure. The results from in vitro antitumour tests indicated that both LW1 and LW2 could significantly inhibit the proliferation of HT-29 colorectal cancer cells and up-regulated the expressions of Bad, Bax, Caspase-3 and -8 genes. Finally, TEM images revealed the apoptotic morphological changes of HT-29 cells induced by LW1 and LW2. Our results suggested that LW1 and LW2 possess potential not only for use in functional food products but also as a source of natural antitumour drugs. Copyright © 2017 Elsevier Ltd. All rights reserved.

Comparison between gastrostomy feeding and self-expandable metal stent insertion for patients with esophageal cancer and dysphagia.

PubMed

Min, Yang Won; Jang, Eun Young; Jung, Ji Hey; Lee, Hyuk; Min, Byung-Hoon; Lee, Jun Haeng; Rhee, Poong-Lyul; Kim, Jae J

2017-01-01

Self-expandable metal stent (SEMS) insertion and percutaneous gastrostomy (PG) feeding are commonly used for patients with esophageal cancer and dysphagia. This study aimed to compare outcomes between SEMS insertion and PG feeding for them. We retrospectively analyzed 308 patients with esophageal cancer who underwent fully covered SEMS insertion (stent group) or PG (gastrostomy group) for dysphagia due to tumor. Patients with other causes of dysphagia, such as radiation-induced or postoperative stricture, were excluded from the study. Clinical outcomes were compared between the two groups, including overall survival and need for additional intervention and postprocedural nutritional status. At baseline, the stent group (n = 169) had more stage IV patients, less cervical cancers, and received radiotherapy and esophagectomy less often than the gastrostomy group (n = 64). The Kaplan-Meier curves showed higher overall survival in the gastrostomy group than in the stent group. Multivariate analysis revealed that PG was associated with better survival compared with SEMS insertion (hazard ratio 0.541, 95% confidence interval 0.346-0.848, p = 0.007). In addition, the gastrostomy group needed additional intervention less often (3.1% vs. 21.9%, p < 0.001) and experienced less decrease in serum albumin levels (-0.15 ± 0.56 g/dL vs. -0.39 ± 0.58 g/dL, p = 0.011) than the stent group after procedure. Our data suggested that, compared with SEMS insertion, PG is associated with better overall survival in patients with esophageal cancer and dysphagia. Stabilized nutritional status by PG may play a role in improving patient survival.

Sexually Explicit Media on the Internet: A Content Analysis of Sexual Behaviors, Risk, and Media Characteristics in Gay Male Adult Videos

PubMed Central

Downing, Martin J.; Schrimshaw, Eric W.; Antebi, Nadav; Siegel, Karolynn

2013-01-01

Recent research suggests that viewing sexually explicit media (SEM), i.e., adult videos, may influence sexual risk taking among men who have sex with men (MSM). Despite this evidence, very little is known about the content of gay male SEM on the Internet, including the prevalence of sexual risk behaviors and their relation to video- and performer-characteristics, viewing frequency, and favorability. The current study content analyzed 302 sexually explicit videos featuring male same-sex performers that were posted to five highly trafficked adult-oriented websites. Findings revealed that gay male SEM on the Internet features a variety of conventional and nonconventional sexual behaviors. There was a substantial prevalence of unprotected anal intercourse (UAI) (34%) and was virtually the same as the prevalence of anal sex with a condom (36%). The presence of UAI was not associated with video length, amateur production, number of video views, favorability, or website source. However, the presence of other potentially high-risk behaviors (e.g., ejaculation in the mouth, and ejaculation on/in/rubbed into the anus) was associated with longer videos, more views, and group sex videos (three or more performers). The findings of high levels of sexual risk behavior and the fact that there was virtually no difference in the prevalence of anal sex with and without a condom in gay male SEM have important implications for HIV prevention efforts, future research on the role of SEM on sexual risk taking, and public health policy. PMID:23733156

Bioaccumulation and distribution of selenium in Enterococcus durans.

PubMed

Pieniz, Simone; Andreazza, Robson; Mann, Michele Bertoni; Camargo, Flávio; Brandelli, Adriano

2017-03-01

Selenium is an essential nutrient for all living organisms. Under appropriate conditions lactic acid bacteria (LAB) are capable for accumulating large amounts of trace elements, such as selenium, and incorporating them into organic compounds. In this study, the capacity of selenium bioaccumulation by Enterococcus durans LAB18s was evaluated. The distribution of organic selenium in selenium-enriched E. durans LAB18s biomass was analyzed, and the highest percentage of organic selenium was found in the fraction of total protein, followed by the fractions of polysaccharides and nucleic acids. When the protein fraction was obtained by different extractions (water, NaCl, ethanol and NaOH) it was demonstrated that alkali-soluble protein showed the higher Selenium content. Analysis of protein fractions by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) revealed that selenium was present in the proteins ranging from 23 to 100kDa. The cells were analyzed by scanning electron microscopy (SEM); scanning electron microscopy/energy dispersive spectrometry (SEM/EDS) and transmission electron microscopy (TEM). SEM, TEM and SEM/EDS showed the morphology, the selenium particles bioaccumulated into and on the cells and the amounts of selenium present into the cells, respectively. Thus, the isolate E. durans LAB18s can be a promising probiotic to be used as selenium-enriched biomass in feed trials. Copyright © 2016 Elsevier GmbH. All rights reserved.

A selective biomarker for confirming nitrofurazone residues in crab and shrimp using ultra-performance liquid chromatography-tandem mass spectrometry.

PubMed

Zhang, Shuai; Guo, Yuanming; Yan, Zhongyong; Sun, Xiumei; Zhang, Xiaojun

2015-12-01

Reliably detecting nitrofurazone (NFZ) residues in farmed crab and shrimp was previously hindered by lack of appropriately specific analytical methodology. Parent NFZ rapidly breaks down in meat, and the commonly used side-chain metabolite, semicarbazide (SEM), is non-specific as it occurs naturally in crustacean shell often leading to 'false positive' detections in meat. Using 5-nitro-2-furaldehyde (NF) as marker metabolite, following pre-column derivatization with 2,4-dinitrophenylhydrazine (DNPH), ultra-performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) analysis in negative electrospray ionization mode enabled confirmation of NFZ residues in deliberately treated whole crab, crab meat and shrimp meat, with a limit of detection (LOD) and limit of quantification (LOQ) below 1 ng g(-1). Meanwhile, the derivatives of DNPH-NF were synthesized for the first time, purified by preparative liquid chromatography and structure characterized with nuclear magnetic resonance spectroscopy ((1)H-NMR). The purity of derivative was checked by ultra-performance liquid chromatography-tunable ultraviolet (UPLC-TUV), and the contents were beyond 99.9%. For comparison purposes, crustacean samples were analysed using both NF and SEM marker metabolites. NFZ treatment was revealed by both NF and SEM marker metabolites, but untreated crab also showed measurable levels of SEM which could potentially be misinterpreted as evidence of illegal NFZ use.

SEM-induced shrinkage and site-selective modification of single-crystal silicon nanopores

NASA Astrophysics Data System (ADS)

Chen, Qi; Wang, Yifan; Deng, Tao; Liu, Zewen

2017-07-01

Solid-state nanopores with feature sizes around 5 nm play a critical role in bio-sensing fields, especially in single molecule detection and sequencing of DNA, RNA and proteins. In this paper we present a systematic study on shrinkage and site-selective modification of single-crystal silicon nanopores with a conventional scanning electron microscope (SEM). Square nanopores with measurable sizes as small as 8 nm × 8 nm and rectangle nanopores with feature sizes (the smaller one between length and width) down to 5 nm have been obtained, using the SEM-induced shrinkage technique. The analysis of energy dispersive x-ray spectroscopy and the recovery of the pore size and morphology reveal that the grown material along with the edge of the nanopore is the result of deposition of hydrocarbon compounds, without structural damage during the shrinking process. A simplified model for pore shrinkage has been developed based on observation of the cross-sectional morphology of the shrunk nanopore. The main factors impacting on the task of controllably shrinking the nanopores, such as the accelerating voltage, spot size, scanned area of e-beam, and the initial pore size have been discussed. It is found that single-crystal silicon nanopores shrink linearly with time under localized irradiation by SEM e-beam in all cases, and the pore shrinkage rate is inversely proportional to the initial equivalent diameter of the pore under the same e-beam conditions.

Connected component analysis of review-SEM images for sub-10nm node process verification

NASA Astrophysics Data System (ADS)

Halder, Sandip; Leray, Philippe; Sah, Kaushik; Cross, Andrew; Parisi, Paolo

2017-03-01

Analysis of hotspots is becoming more and more critical as we scale from node to node. To define true process windows at sub-14 nm technology nodes, often defect inspections are being included to weed out design weak spots (often referred to as hotspots). Defect inspection sub 28 nm nodes is a two pass process. Defect locations identified by optical inspection tools need to be reviewed by review-SEM's to understand exactly which feature is failing in the region flagged by the optical tool. The images grabbed by the review-SEM tool are used for classification but rarely for quantification. The goal of this paper is to see if the thousands of review-SEM images which are existing can be used for quantification and further analysis. More specifically we address the SEM quantification problem with connected component analysis.

In Situ Characterization of Boehmite Particles in Water Using Liquid SEM

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

Yao, Juan; Arey, Bruce W.; Yang, Li

In situ imaging and elemental analysis of boehmite (AlOOH) particles in water is realized using the System for Analysis at the Liquid Vacuum Interface (SALVI) and Scanning Electron Microscopy (SEM). This paper describes the method and key steps in integrating the vacuum compatible SAVLI to SEM and obtaining secondary electron (SE) images of particles in liquid in high vacuum. Energy dispersive x-ray spectroscopy (EDX) is used to obtain elemental analysis of particles in liquid. A synthesized AlOOH particle is used as a model in the liquid SEM illustration. Our results demonstrate that particles can be imaged in the SE modemore » with good resolution. The AlOOH EDX spectrum shows significant signal from the Al compared with deionized water and the empty channel control. In situ liquid SEM is a powerful technique to study particles in liquid with many exciting applications. This procedure aims to provide technical details in how to conduct liquid SEM imaging and EDX analysis using SALVI and reduce potential pitfalls using this approach for other researchers.« less

The relationship between cost estimates reliability and BIM adoption: SEM analysis

NASA Astrophysics Data System (ADS)

Ismail, N. A. A.; Idris, N. H.; Ramli, H.; Rooshdi, R. R. Raja Muhammad; Sahamir, S. R.

2018-02-01

This paper presents the usage of Structural Equation Modelling (SEM) approach in analysing the effects of Building Information Modelling (BIM) technology adoption in improving the reliability of cost estimates. Based on the questionnaire survey results, SEM analysis using SPSS-AMOS application examined the relationships between BIM-improved information and cost estimates reliability factors, leading to BIM technology adoption. Six hypotheses were established prior to SEM analysis employing two types of SEM models, namely the Confirmatory Factor Analysis (CFA) model and full structural model. The SEM models were then validated through the assessment on their uni-dimensionality, validity, reliability, and fitness index, in line with the hypotheses tested. The final SEM model fit measures are: P-value=0.000, RMSEA=0.079<0.08, GFI=0.824, CFI=0.962>0.90, TLI=0.956>0.90, NFI=0.935>0.90 and ChiSq/df=2.259; indicating that the overall index values achieved the required level of model fitness. The model supports all the hypotheses evaluated, confirming that all relationship exists amongst the constructs are positive and significant. Ultimately, the analysis verified that most of the respondents foresee better understanding of project input information through BIM visualization, its reliable database and coordinated data, in developing more reliable cost estimates. They also perceive to accelerate their cost estimating task through BIM adoption.

A scanning electron microscopy study of early development in vitro of Contracaecum multipapillatum s.l. (Nematoda: Anisakidae) from a brown pelican (Pelecanus occidentalis) from the Gulf of California, Mexico.

PubMed

Molina-Fernández, Dolores; Valles-Vega, Isabel; Hernández-Trujillo, Sergio; Adroher, Francisco Javier; Benítez, Rocío

2017-10-01

Eggs obtained from the uteri of female nematodes, genetically identified as Contracaecum multipapillatum s.l., found in a brown pelican (Pelecanus occidentalis) from Bahía de La Paz, Gulf of California, Mexico, were used to study the early developmental stages of this anisakid by scanning electron microscopy (SEM). Egg dimensions were approximately 54 × 45 μm measured by SEM. Observation of the eggs revealed an outer surface of fibrous appearance. The newly hatched larvae were ensheathed and highly motile. Observation with SEM showed that the sheaths of the larvae were striated and revealed an excretory pore and a cleft near the anterior end of the sheath, presumably to facilitate the opening of the sheath for the emergence of the larva. The hatched larvae were placed in nutritive culture medium, where they grew within their sheath, some exsheathing completely 2 weeks later. The surface patterns of the sheath and the cuticle of the exsheathed larvae were clearly different. Although they did not moult during culture, SEM revealed a morphology typical of third-stage larvae of Contracaecum from fish, as previously observed by optical microscopy. Thus, we suggest that newly hatched larvae from eggs of C. multipapillatum are third larval stage but with sheath of the second larval stage, as occuring in other anisakids.

Cooked Food Waste-An Efficient and Less Expensive Precursor for the Generation of Activated Carbon.

PubMed

Krithiga, Thangavelu; Sabina, Xavier Janet; Rajesh, Baskaran; Ilbeygi, Hamid; Shetty, Adka Nityananda; Reddy, Ramanjaneya; Karthikeyan, Jayabalan

2018-06-01

Activated carbon was synthesized from cooked food waste, especially dehydrated rice kernels, by chemical activation method using NaOH and KOH as activating agents. It was then characterized by ultimate and proximate analysis, BET surface analysis, XRD, FTIR, Raman and SEM. The XRD patterns and Raman spectra confirmed the amorphous nature of the prepared activated carbons. Ultimate analysis showed an increase in the carbon content after activation of the raw carbon samples. Upon activation with NaOH and KOH, the surface area of the carbon sample was found to have increased from 0.3424 to 539.78 and 306.83 m2g-1 respectively. The SEM images revealed the formation of heterogeneous pores on the surface of the activated samples. The samples were then tested for their adsorption activity using acetic acid and methylene blue. Based on the regression coefficients, the adsorption kinetics of methylene blue dye were fitted with pseudo-second order model for both samples. Similarly, the Freundlich isotherm was found to be a better fit than Langmuir isotherm for both samples. The activity of thus prepared activated carbons was found to be comparable with the commercial carbon.

Comparative studies of mononuclear Ni(II) and UO2(II) complexes having bifunctional coordinated groups: Synthesis, thermal analysis, X-ray diffraction, surface morphology studies and biological evaluation

NASA Astrophysics Data System (ADS)

Fahem, Abeer A.

2012-03-01

Two Schiff base ligands derived from condensation of phthalaldehyde and o-phenylenediamine in 1:2 (L1) and 2:1 (L2) having bifunctional coordinated groups (NH2 and CHO groups, respectively) and their metal complexes with Ni(II) and UO2(II) have been synthesized and characterized by elemental analysis, molar conductance, magnetic susceptibilities and spectral data (IR, 1H NMR, mass and solid reflectance) as well as thermal, XRPD and SEM analysis. The formula [Ni(L1)Cl2]·2.5H2O, [UO2(L1)(NO3)2]·2H2O, [Ni(L2)Cl2]·1.5H2O and [UO2(L2)(NO3)2] have been suggested for the complexes. The vibrational spectral data show that the ligands behave as neutral ligands and coordinated to the metal ions in a tetradentate manner. The Ni(II) complexes are six coordinate with octahedral geometry and the ligand field parameters: Dq, B, β and LFSE were calculated while, UO2(II) complexes are eight coordinate with dodecahedral geometry and the force constant, FUsbnd O and bond length, RUsbnd O were calculated. The thermal decomposition of complexes ended with metal chloride/nitrate as a final product and the highest thermal stability is displayed by [UO2(L2)(NO3)2] complex. The X-ray powder diffraction data revealed the formation of nano sized crystalline complexes. The SEM analysis provides the morphology of the synthesized compounds and SEM image of [UO2(L2)(NO3)2] complex exhibits nano rod structure. The growth-inhibiting potential of the ligands and their complexes has been assessed against a variety of bacterial and fungal strains.

SEM-EDX analysis in the source apportionment of particulate matter on Hypogymnia physodes lichen transplants around the Cu smelter and former mining town of Karabash, South Urals, Russia.

PubMed

Williamson, B J; Mikhailova, I; Purvis, O W; Udachin, V

2004-04-25

Scanning electron microscopy with energy-dispersive X-ray analysis (SEM-EDX) of particulate matter on lichen transplant thalli (Hypogymnia physodes) was assessed as a complementary technique to wet chemical analysis for source apportionment of airborne contaminants. Transplants (2 month exposure) stationed in the Cu smelter and former mining town of Karabash were compared with those from a control site 30 km south. Particulate matter in Karabash samples (715 analyses) showed higher levels of S, Pb, Cu, Sn and Zn compared with the control (598 analyses). Complex element associations among the particles confounded detailed mineralogical identifications, and therefore a simplified particle classification scheme was devised for source apportionment. Karabash samples contained high levels of particles classified as mining-related (MRP), and these were also identified in control samples, indicating wide spatial dispersion from the smelter and highlighting the sensitivity of the method. It was noted that MRP <2.5-microm diameter were poorly represented on lichen surfaces suggesting this may limit the usefulness of Hypogymnia transplants as proxies when assessing human health impacts from airborne particulates. Analyses of the lichen thallus surface (away from surface particulates) revealed high levels of Cu, Zn, Fe and Pb associated with organics in the Karabash samples compared with the control, with a proportionate loss of K, interpreted as being due to a stress-related increase in cell membrane permeability. This type of analysis may provide a novel SEM-EDX-based method for assessing lichen vitality. The techniques developed are presented and further implications of the study are discussed.

Synthesis and characterization of an effective organic/inorganic hybrid green corrosion inhibitive complex based on zinc acetate/Urtica Dioica

NASA Astrophysics Data System (ADS)

Salehi, E.; Naderi, Reza; Ramezanzadeh, B.

2017-02-01

This study aims at synthesis and characterization of an effective corrosion inhibitive complex based on zinc acetate/Urtica Dioica (ZnA-U.D) for corrosion protection of mild steel in chloride solution. The chemical structure and morphology of the complex were characterized by Fourier transform infrared spectroscopy (FT-IR), UV-vis, thermal gravimetric analysis (TGA), X-ray photoelectron spectroscopy (XPS) and scanning electron microscopy (SEM). The corrosion protection performance of the mild steel samples dipped in 3.5 wt.% NaCl solutions with and without ZnA-U.D extract was investigated by visual observations, open circuit potential (OCP) measurements, electrochemical impedance spectroscopy (EIS) and polarization test. Results revealed that the ZnA successfully chelated with organic inhibitive compounds (i.e Quercetin, Quinic acid, Caffeic acid, Hystamine and Serotonin) present in the U.D extract. The electrochemical measurements revealed the effective inhibition action of ZnA-U.D complex in the sodium chloride solution on the mild steel. The synergistic effect between Zn2+ and organic compounds present in the U.D extract resulted in protective film deposition on the steel surface, which was proved by SEM and XPS analyses.

Mechanistic Insight into the Elastin Degradation Process by the Metalloprotease Myroilysin from the Deep-Sea Bacterium Myroides profundi D25

PubMed Central

Yang, Jie; Zhao, Hui-Lin; Tang, Bai-Lu; Chen, Xiu-Lan; Su, Hai-Nan; Zhang, Xi-Ying; Song, Xiao-Yan; Zhou, Bai-Cheng; Xie, Bin-Bin; Weiss, Anthony S.; Zhang, Yu-Zhong

2015-01-01

Elastases have been widely studied because of their important uses as medicine and meat tenderizers. However, there are relatively few studies on marine elastases. Myroilysin, secreted by Myroides profundi D25 from deep-sea sediment, is a novel elastase. In this study, we examined the elastin degradation mechanism of myroilysin. When mixed with insoluble bovine elastin, myroilysin bound hydrophobically, suggesting that this elastase may interact with the hydrophobic domains of elastin. Consistent with this, analysis of the cleavage pattern of myroilysin on bovine elastin and recombinant tropoelastin revealed that myroilysin preferentially cleaves peptide bonds with hydrophobic residues at the P1 and/or P1′ positions. Scanning electron microscopy (SEM) of cross-linked recombinant tropoelastin degraded by myroilysin showed preferential damages of spherules over cross-links, as expected for a hydrophobic preference. The degradation process of myroilysin on bovine elastin fibres was followed by light microscopy and SEM, revealing that degradation begins with the formation of crevices and cavities at the fibre surface, with these openings increasing in number and size until the fibre breaks into small pieces, which are subsequently fragmented. Our results are helpful for developing biotechnological applications for myroilysin. PMID:25793427

Evaluation of Microstructure and Mechanical Properties of Al-TiC Metal Matrix Composite Prepared by Conventional, Microwave and Spark Plasma Sintering Methods

PubMed Central

Ghasali, Ehsan; Fazili, Ali; Alizadeh, Masoud; Shirvanimoghaddam, Kamyar; Ebadzadeh, Touradj

2017-01-01

In this research, the mechanical properties and microstructure of Al-15 wt % TiC composite samples prepared by spark plasma, microwave, and conventional sintering were investigated. The sintering process was performed by the speak plasma sintering (SPS) technique, microwave and conventional furnaces at 400 °C, 600 °C, and 700 °C, respectively. The results showed that sintered samples by SPS have the highest relative density (99% of theoretical density), bending strength (291 ± 12 MPa), and hardness (253 ± 23 HV). The X-ray diffraction (XRD) investigations showed the formation of TiO2 from the surface layer decomposition of TiC particles. Scanning electron microscopy (SEM) micrographs demonstrated uniform distribution of reinforcement particles in all sintered samples. The SEM/EDS analysis revealed the formation of TiO2 around the porous TiC particles. PMID:29088114

Processing and Characterization of Fe-Mn-Cu-Sn-C Alloys Prepared by Ball Milling and Spark Plasma Sintering

NASA Astrophysics Data System (ADS)

Bączek, Elżbieta; Konstanty, Janusz; Romański, Andrzej; Podsiadło, Marcin; Cyboroń, Jolanta

2018-03-01

In this work, Fe-Mn-Cu-Sn-C alloys were prepared by means of powder metallurgy (PM). Powder mixtures were ball-milled for 8, 30 and 120 h and densified to < 1% porosity using spark plasma sintering (SPS) at 900 °C and 35 MPa. After consolidation, all samples of the Fe alloys were characterized by x-ray diffraction (XRD), scanning electron microscopy (SEM), hardness and flexural strength tests. Resistance to abrasive wear was evaluated in both three-body abrasion and two-body abrasion tests. The SEM observations revealed an evident dependence of grain size and microstructural homogeneity on milling time. The XRD analysis showed a marked increase in austenite content in the as-sintered specimens with milling time. Although the proportion of deformation-induced martensite was small, the strengthening effect of abrasion on the subsurface layer of the investigated alloys was clearly indicated by Knoop hardness measurements.

The effects of deposition parameters on surface morphology and crystallographic orientation of electroless Ni-B coatings

NASA Astrophysics Data System (ADS)

Bulbul, Ferhat

2011-02-01

Electroless Ni-B coatings were deposited on AISI 304 stainless steels by electroless deposition method, which was performed for nine different test conditions at various levels of temperature, concentration of NaBH4, concentration of NiCl2, and time, using the Taguchi L9(34) experimental method. The effects of deposition parameters on the crystallographic orientation of electroless Ni-B coatings were investigated using SEM and XRD equipment. SEM analysis revealed that the Ni-B coatings developed six types (pea-like, maize-like, primary nodular, blackberry-like or grapes-like, broccoli-like, and cauliflower-like) of morphological structures depending on the deposition parameters. XRD results also showed that these structures exhibited different levels of amorphous character. The concentration of NaBH4 had the most dominant effect on the morphological and crystallographic development of electroless Ni-B coatings.

[Spectral characteristics of decomposition of incorporated straw in compound polluted arid loess].

PubMed

Fan, Chun-Hui; Zhang, Ying-Chao; Xu, Ji-Ting; Wang, Jia-Hong

2014-04-01

The original loess from western China was used as soil sample, the spectral methods of scanning electron microscope-energy dispersive X-ray spectroscopy (SEM-EDS), elemental analysis, Fourier transform infrared spectroscopy (FT-IR) and 13C nuclear magnetic resonance (13C NMR) were used to investigate the characteristics of decomposed straw and formed humic acids in compound polluted arid loess. The SEM micrographs show the variation from dense to decomposed surface, and finally to damaged structure, and the EDS data reveal the phenomenon of element transfer. The newly-formed humic acids are of low aromaticity, helpful for increasing the activity of organic matters in loess. The FTIR spectra in the whole process are similar, indicating the complexity of transformation dynamics of humic acids. The molecular structure of humic acids becomes simpler, shown from 13C NMR spectra. The spectral methods are useful for humic acids identification in loess region in straw incorporation process.

Surface morphology of chitin highly related with the isolated body part of butterfly (Argynnis pandora).

PubMed

Kaya, Murat; Bitim, Betül; Mujtaba, Muhammad; Koyuncu, Turgay

2015-11-01

This study was conducted to understand the differences in the physicochemical properties of chitin samples isolated from the wings and the other body parts except the wings (OBP) of a butterfly species (Argynnis pandora). The same isolation method was used for obtaining chitin specimens from both types of body parts. The chitin content of the wings (22%) was recorded as being much higher than the OBP (8%). The extracted chitin samples were characterized via FT-IR, TGA, XRD, SEM, and elemental analysis techniques. Results of these characterizations revealed that the chitins from both structures (wings and OBP) were very similar, except for their surface morphologies. SEM results demonstrated one type of surface morphology for the wings and four different surface morphologies for the OBP. Therefore, it can be hypothesized that the surface morphology of the chitin is highly related with the body part. Copyright © 2015 Elsevier B.V. All rights reserved.

Oxygen ion irradiation effect on corrosion behavior of titanium in nitric acid medium

NASA Astrophysics Data System (ADS)

Ningshen, S.; Kamachi Mudali, U.; Mukherjee, P.; Barat, P.; Raj, Baldev

2011-01-01

The corrosion assessment and surface layer properties after O 5+ ion irradiation of commercially pure titanium (CP-Ti) has been studied in 11.5 N HNO 3. CP-Ti specimen was irradiated at different fluences of 1 × 10 13, 1 × 10 14 and 1 × 10 15 ions/cm 2 below 313 K, using 116 MeV O 5+ ions source. The corrosion resistance and surface layer were evaluated by using potentiodynamic polarization, electrochemical impedance spectroscopy (EIS), scanning electron microscopy (SEM) and glancing-angle X-ray diffraction (GXRD) methods. The potentiodynamic anodic polarization results of CP-Ti revealed that increased in ion fluence (1 × 10 13-1 × 10 15 ions/cm 2) resulted in increased passive current density due to higher anodic dissolution. SEM micrographs and GXRD analysis corroborated these results showing irradiation damage after corrosion test and modified oxide layer by O 5+ ion irradiation was observed. The EIS studies revealed that the stability and passive film resistance varied depending on the fluence of ion irradiation. The GXRD patterns of O 5+ ion irradiated CP-Ti revealed the oxides formed are mostly TiO 2, Ti 2O 3 and TiO. In this paper, the effects of O 5+ ion irradiation on material integrity and corrosion behavior of CP-Ti in nitric acid are described.

The relation between family adversity and social anxiety among adolescents in Taiwan: effects of family function and self-esteem.

PubMed

Yen, Cheng-Fang; Yang, Pinchen; Wu, Yu-Yu; Cheng, Chung-Ping

2013-11-01

This study aimed to examine the relationship between three indicators of family adversity (domestic violence, family substance use, and broken parental marriage) and the severity of social anxiety among adolescents in Taiwan, as well as the mediating effects of perceived family function and self-esteem on that relationship, using structural equation modeling (SEM). A total of 5607 adolescents completed the social anxiety subscale of the Multidimensional Anxiety Scale for Children; the Family APGAR Index; the Rosenberg Self-Esteem Scale; and a questionnaire for domestic violence, family substance use, and broken parental marriage. The relation between family adversity and social anxiety, as well as the mediating effects of family function and self-esteem, was examined using SEM. SEM analysis revealed that all three indicators of family adversity reduced the level of family function, that decreased family function compromised the level of self-esteem, and that a low level of self-esteem further increased the severity of social anxiety. The results indicated that, along with intervening to change family adversity, evaluating and improving adolescents' self-esteem and family function are also important clinical issues when helping adolescents reduce their social anxiety.

Relationships among Communication Self-Efficacy, Communication Burden, and the Mental Health of the Families of Persons with Aphasia.

PubMed

Tatsumi, Hiroshi; Nakaaki, Shutaro; Satoh, Masayuki; Yamamoto, Masahiko; Chino, Naohito; Hadano, Kazuo

2016-01-01

The purpose of this study was to elucidate the relationships among communication self-efficacy (SE), communication burden, and the mental health of the families of persons with aphasia using structural equation modeling (SEM). This study examined 110 pairs of persons with aphasia receiving home care and 1 family caregiver per person with aphasia. The survey items for this study consisted of the Communication Self-efficacy Scale, the Communication Burden Scale, the Geriatric Depression Scale-Short Form-Japanese, and the Health-Related Quality of Life: SF-8 Health Survey. The relationships between the constructive concept of "communication self-efficacy" and "communication burden," and "mental-health status" were analyzed using SEM. The results of the SEM analysis revealed that a high communication SE of the families was associated with low burden of communication and good mental-health status. Psychoeducational programs that address the communication SE of family caregivers may have the potential to reduce the burden of communication and to improve the mental health of caregivers. These programs could lead to an enhanced quality of life for both persons with aphasia and their families. Copyright © 2015 National Stroke Association. Published by Elsevier Inc. All rights reserved.

PVP capped CdS nanoparticles for UV-LED applications

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

Sivaram, H.; Selvakumar, D.; Jayavel, R., E-mail: rjvel@annauniv.edu

Polyvinlypyrrolidone (PVP) capped cadmium sulphide (CdS) nanoparticles are synthesized by wet chemical method. The powder X-ray diffraction (XRD) result indicates that the nanoparticles are crystallized in cubic phase. The optical properties are characterized by UV-Vis absorption. The morphology of CdS nanoparticles are studied using Scanning electron microscope (SEM). The thermal behavior of the as prepared nanoparticles has been examined by Thermo gravimetric analysis (TGA). The optical absorption study of pvp capped CdS reveal a red shift confirms the UV-LED applications.

Microstructures of Pd-containing dispersants for admixed dental amalgams.

PubMed

Chern Lin, J H; Greener, E H

1991-10-01

Blended Pd-containing dispersants were developed by the utilization of a Ag-Cu eutectic into which Pd was substituted for Ag or Cu in concentrations of up to 20 wt%. Compositions were melted either in argon-filled sealed vycor tubes or in a graphite-linked carbon crucible of an induction furnace with an argon blanket. Ingots of approximately 1.5 cm in diameter were sectioned to 0.2 cm in thickness and polished through standard metallographic polishing procedures. The possible compounds were identified by XRD. The microstructures of the alloys were examined by SEM/EDS. XRD analysis of the alloys revealed the preferential dissolution of Pd in Cu when the Pd concentration was less than or equal to 10 wt%. When the Pd concentration exceeded 20 wt%, Pd was found to be dissolved in both Ag and Pd. No Cu3Pd x-ray diffraction peaks were found for alloys with Pd concentration of up to 20 wt%. SEM/EDS analysis confirmed XRD results; lamellae of Ag and Cu-Pd were found in alloys with Pd concentration less than or equal to 10 wt%.

Combined PIXE and X-ray SEM studies on time-resolved deposits of welding shop aerosols

NASA Astrophysics Data System (ADS)

Barfoot, K. M.; Mitchell, I. V.; Verheyen, F.; Babeliowsky, T.

1981-03-01

Time-resolved deposits of welding shop air particulates have been obtained using a streak sampling system. PIXE analysis of these deposits, using 2 MeV protons, typically revealed the presence of a large number of elements, with many in the range Z = 11-30. Strong variations, up to three orders of magnitude, in the concentrations of several elements such as Al, Si and Fe as well as Zn, Na, K and Ca were found. The 2 h sampling resolution normally used was found to be insufficient to follow the short pollution episodes that regularly occur in a welding shop environment and so sampling with a 20 min resolution was used. The variation of elemental concentrations for different sampling times together with information on the physical nature of these air particulates, determined with a scanning electron microscope (SEM) and Si(Li) X-ray detector attachment, are presented. This type of information together with that obtained from the PIXE analysis is of importance in industrial hygiene studies. The need to make corrections for partial filter clogging, based on air-flow rate monitoring, is discussed.

SEM and TEM Analyses of Minerals Xifengite, Gupeiite, Fe2Si (Hapkeite?), Titanium Carbide (TiC) and Cubic Moissanite (SiC) from the Subsoil in the Alpine Foreland: Are they Cosmochemical?

NASA Astrophysics Data System (ADS)

Hiltl, M.; Bauer, F.; Ernstson, K.; Mayer, W.; Neumair, A.; Rappenglück, M. A.

2011-03-01

SEM and TEM analyses of millimeter- to centimeter-sized particles from Holocene soils reveal a multi-stoichiometric iron silicide matrix containing purest crystals of titanium carbide and cubic moissanite. A cosmochemical origin is suggested.

Karyotype variation in cultivars and spontaneous cocoa mutants (Theobroma cacao L.).

PubMed

Figueiredo, G S F; Melo, C A F; Souza, M M; Araújo, I S; Zaidan, H A; Pires, J L; Ahnert, D

2013-10-18

Four mutant cocoa accessions with morphological changes and a cultivar sample were karyomorphologically characterized. Slides were prepared by enzymatic digestion of the root meristem and squashed in 45% acetic acid, followed by 2% Giemsa staining. The chromosome number of 2n = 20 was seen in all accessions. The karyotype formula for Cacau Comum and Cacau Rui was 2n = 20m. Submetacentric chromosomes were observed in Cacau Pucala and Cacau Jaca, both with 2n = 18m + 2sm, but the karyotype formula for Cacau Sem Vidro was 2n = 16m + 4sm. Satellites were located on the long arm of the 1st and 2nd chromosome pairs of Cacau Comum, whereas Cacau Pucala had satellites on the 6th chromosome pair. Greater karyotypic variation in Cacau Sem Vidro was found, whose 1st and 2nd chromosome pairs had satellites on the long arm and 6th and 10th pairs had satellites on the short arm. Analysis revealed a lower average chromosome length in Cacau Comum (1.53 ± 0.026 µm) and a higher length in Cacau Sem Vidro (2.26 ± 0.038 µm). ANOVA revealed significant difference (P < 0.01) for the average chromosome length and the length of chromosome pairs within and between accessions. The average chromosome lengths of mutants of Cacau Rui and Cacau Jaca were not statistically different by the Tukey test at 5% probability. The karyotypic diversity observed in this study is not necessarily associated with the changing character of the accessions analyzed, but may reflect the genetic variation observed in Theobroma cacao.

Structural analysis of HyFlex EDM instruments.

PubMed

Iacono, F; Pirani, C; Generali, L; Bolelli, G; Sassatelli, P; Lusvarghi, L; Gandolfi, M G; Giorgini, L; Prati, C

2017-03-01

To compare the phase transformation behaviour, the microstructure, the nano-hardness and the surface chemistry of electro-discharge machined HyFlex EDM instruments with conventionally manufactured HyFlex CM. New and laboratory used HyFlex EDM were examined by X-ray diffraction (XRD) and differential scanning calorimetry (DSC). Nano-hardness and modulus of elasticity were also investigated using a maximum load of 20 mN with a minimum of 40 significant indentations for each sample. Raman spectroscopy and field emission-scanning electron microscope (FE-SEM) were used to assess the surface chemistry of HyFlex EDM. HyFlex CM were subjected to the same investigations and used as a comparison. Nano-indentation data were statistically analysed using the Student's t-test. XRD analysis on HyFlex EDM revealed the presence of martensite and rhombohedral R-phase, while a mixture of martensite and austenite structure was identified in HyFlex CM. DSC analysis also disclosed higher austenite finish (Af) temperatures for electro-discharge machining (EDM) instruments. Significant differences in nano-hardness and modulus of elasticity were found between EDM and CM files (P < 0.05). FE-SEM and EDS analyses confirmed that both new EDM and CM files were covered by an oxide layer. Micro-Raman spectroscopy assessed the presence of rutile-TiO 2 . HyFlex EDM revealed peculiar structural properties, such as increased phase transformation temperatures and hardness. Present results corroborated previous findings and shed light on the enhanced mechanical behaviour of these instruments. © 2016 International Endodontic Journal. Published by John Wiley & Sons Ltd.

Chemical Species, Micromorphology, and XRD Fingerprint Analysis of Tibetan Medicine Zuotai Containing Mercury

PubMed Central

Li, Cen; Yang, Hongxia; Xiao, Yuancan; Zhandui; Sanglao; Wang, Zhang; Ladan, Duojie; Bi, Hongtao

2016-01-01

Zuotai (gTso thal) is one of the famous drugs containing mercury in Tibetan medicine. However, little is known about the chemical substance basis of its pharmacodynamics and the intrinsic link of different samples sources so far. Given this, energy dispersive spectrometry of X-ray (EDX), scanning electron microscopy (SEM), atomic force microscopy (AFM), and powder X-ray diffraction (XRD) were used to assay the elements, micromorphology, and phase composition of nine Zuotai samples from different regions, respectively; the XRD fingerprint features of Zuotai were analyzed by multivariate statistical analysis. EDX result shows that Zuotai contains Hg, S, O, Fe, Al, Cu, and other elements. SEM and AFM observations suggest that Zuotai is a kind of ancient nanodrug. Its particles are mainly in the range of 100–800 nm, which commonly further aggregate into 1–30 μm loosely amorphous particles. XRD test shows that β-HgS, S8, and α-HgS are its main phase compositions. XRD fingerprint analysis indicates that the similarity degrees of nine samples are very high, and the results of multivariate statistical analysis are broadly consistent with sample sources. The present research has revealed the physicochemical characteristics of Zuotai, and it would play a positive role in interpreting this mysterious Tibetan drug. PMID:27738409

Chemical Species, Micromorphology, and XRD Fingerprint Analysis of Tibetan Medicine Zuotai Containing Mercury.

PubMed

Li, Cen; Yang, Hongxia; Du, Yuzhi; Xiao, Yuancan; Zhandui; Sanglao; Wang, Zhang; Ladan, Duojie; Bi, Hongtao; Wei, Lixin

2016-01-01

Zuotai ( gTso thal ) is one of the famous drugs containing mercury in Tibetan medicine. However, little is known about the chemical substance basis of its pharmacodynamics and the intrinsic link of different samples sources so far. Given this, energy dispersive spectrometry of X-ray (EDX), scanning electron microscopy (SEM), atomic force microscopy (AFM), and powder X-ray diffraction (XRD) were used to assay the elements, micromorphology, and phase composition of nine Zuotai samples from different regions, respectively; the XRD fingerprint features of Zuotai were analyzed by multivariate statistical analysis. EDX result shows that Zuotai contains Hg, S, O, Fe, Al, Cu, and other elements. SEM and AFM observations suggest that Zuotai is a kind of ancient nanodrug. Its particles are mainly in the range of 100-800 nm, which commonly further aggregate into 1-30  μ m loosely amorphous particles. XRD test shows that β -HgS, S 8 , and α -HgS are its main phase compositions. XRD fingerprint analysis indicates that the similarity degrees of nine samples are very high, and the results of multivariate statistical analysis are broadly consistent with sample sources. The present research has revealed the physicochemical characteristics of Zuotai , and it would play a positive role in interpreting this mysterious Tibetan drug.

Structural Equation Model Trees

ERIC Educational Resources Information Center

Brandmaier, Andreas M.; von Oertzen, Timo; McArdle, John J.; Lindenberger, Ulman

2013-01-01

In the behavioral and social sciences, structural equation models (SEMs) have become widely accepted as a modeling tool for the relation between latent and observed variables. SEMs can be seen as a unification of several multivariate analysis techniques. SEM Trees combine the strengths of SEMs and the decision tree paradigm by building tree…

SIMS analysis of extended impact features on LDEF experiment

NASA Technical Reports Server (NTRS)

Amari, S.; Foote, J.; Jessberger, E. K.; Simon, C.; Stadermann, F. J.; Swan, P.; Walker, R.; Zinner, E.

1991-01-01

Discussed here are the first Secondary Ion Mass Spectroscopy (SIMS) analysis of projectile material deposited in extended impact features on Ge wafers from the trailing edge. Although most capture cells lost their plastic film covers, they contain extended impact features that apparently were produced by high velocity impacts when the plastic foils were still intact. Detailed optical scanning of all bare capture cells from the trailing edge revealed more than 100 impacts. Fifty-eight were selected by scanning electron microscope (SEM) inspection as prime candidates for SIMS analysis. Preliminary SIMS measurements were made on 15 impacts. More than half showed substantial enhancements of Mg, Al, Si, Ca, and Fe in the impact region, indicating micrometeorites as the projectiles.

Sol-gel synthesis of thorn-like ZnO nanoparticles endorsing mechanical stirring effect and their antimicrobial activities: Potential role as nano-antibiotics

PubMed Central

Khan, Mohd Farhan; Ansari, Akhter H.; Hameedullah, M.; Ahmad, Ejaz; Husain, Fohad Mabood; Zia, Qamar; Baig, Umair; Zaheer, Mohd Rehan; Alam, Mohammad Mezbaul; Khan, Abu Mustafa; AlOthman, Zeid A.; Ahmad, Iqbal; Ashraf, Ghulam Md; Aliev, Gjumrakch

2016-01-01

The effect of mechanical stirring on sol-gel synthesis of thorn-like ZnO nanoparticles (ZnO-NPs) and antimicrobial activities is successfully reported in this study. The in-house synthesized nanoparticles were characterized by XRD, SEM, TEM, FTIR, TGA, DSC and UV-visible spectroscopy. The X-Ray Diffraction analysis revealed the wurtzite crystal lattice for ZnO-NPs with no impurities present. The diametric measurements of the synthesized thorn-like ZnO-NPs (morphology assessed by SEM) were well accounted to be less than 50 nm with the help of TEM. Relative decrease in aspect ratio was observed on increasing the agitation speed. The UV-visible spectroscopy showed the absorption peaks of the ZnO-NPs existed in both UVA and UVB region. A hypsochromic shift in λmax was observed when stirring pace was increased from 500 rpm to 2000 rpm. The FTIR spectroscopy showed the absorption bands of the stretching modes of Zn-O between 500 cm−1 to 525 cm−1. The Thermal analysis studies revealed better stability for ZnO-NPs prepared at 2000 rpm (ZnO-2000 rpm). TGA revealed the weight loss between two main temperatures ranges viz. around (90 °C–120 °C) and (240 °C–280 °C). Finally, the effect of ZnO-NPs prepared at different stirring conditions on the growth of Gram-positive (Bacillus subtilis), Gram-negative (Escherichia coli) bacteria and a fungi (Candida albicans) were examined; which showed good antibacterial as well as antifungal properties. These findings introduce a simple, inexpensive process to synthesize ZnO-NPs using conventional methods without the use of sophisticated equipments and its application as a potent nano-antibiotic. PMID:27349836

In Situ Characterization of Boehmite Particles in Water Using Liquid SEM.

PubMed

Yao, Juan; Arey, Bruce W; Yang, Li; Zhang, Fei; Komorek, Rachel; Chun, Jaehun; Yu, Xiao-Ying

2017-09-27

In situ imaging and elemental analysis of boehmite (AlOOH) particles in water is realized using the System for Analysis at the Liquid Vacuum Interface (SALVI) and Scanning Electron Microscopy (SEM). This paper describes the method and key steps in integrating the vacuum compatible SAVLI to SEM and obtaining secondary electron (SE) images of particles in liquid in high vacuum. Energy dispersive x-ray spectroscopy (EDX) is used to obtain elemental analysis of particles in liquid and control samples including deionized (DI) water only and an empty channel as well. Synthesized boehmite (AlOOH) particles suspended in liquid are used as a model in the liquid SEM illustration. The results demonstrate that the particles can be imaged in the SE mode with good resolution (i.e., 400 nm). The AlOOH EDX spectrum shows significant signal from the aluminum (Al) when compared with the DI water and the empty channel control. In situ liquid SEM is a powerful technique to study particles in liquid with many exciting applications. This procedure aims to provide technical know-how in order to conduct liquid SEM imaging and EDX analysis using SALVI and to reduce potential pitfalls when using this approach.

Comparison between gastrostomy feeding and self-expandable metal stent insertion for patients with esophageal cancer and dysphagia

PubMed Central

Jung, Ji Hey; Lee, Hyuk; Min, Byung-Hoon; Lee, Jun Haeng; Rhee, Poong-Lyul; Kim, Jae J.

2017-01-01

Background Self-expandable metal stent (SEMS) insertion and percutaneous gastrostomy (PG) feeding are commonly used for patients with esophageal cancer and dysphagia. This study aimed to compare outcomes between SEMS insertion and PG feeding for them. Methods We retrospectively analyzed 308 patients with esophageal cancer who underwent fully covered SEMS insertion (stent group) or PG (gastrostomy group) for dysphagia due to tumor. Patients with other causes of dysphagia, such as radiation-induced or postoperative stricture, were excluded from the study. Clinical outcomes were compared between the two groups, including overall survival and need for additional intervention and postprocedural nutritional status. Results At baseline, the stent group (n = 169) had more stage IV patients, less cervical cancers, and received radiotherapy and esophagectomy less often than the gastrostomy group (n = 64). The Kaplan-Meier curves showed higher overall survival in the gastrostomy group than in the stent group. Multivariate analysis revealed that PG was associated with better survival compared with SEMS insertion (hazard ratio 0.541, 95% confidence interval 0.346–0.848, p = 0.007). In addition, the gastrostomy group needed additional intervention less often (3.1% vs. 21.9%, p < 0.001) and experienced less decrease in serum albumin levels (-0.15 ± 0.56 g/dL vs. -0.39 ± 0.58 g/dL, p = 0.011) than the stent group after procedure. Conclusions Our data suggested that, compared with SEMS insertion, PG is associated with better overall survival in patients with esophageal cancer and dysphagia. Stabilized nutritional status by PG may play a role in improving patient survival. PMID:28632744

The effect of home bleaching agents on the surface roughness of five different composite resins: A SEM evaluation.

PubMed

Cengiz, Esra; Kurtulmus-Yilmaz, Sevcan; Ulusoy, Nuran; Deniz, Sule Tugba; Yuksel-Devrim, Ece

2016-05-01

The aim of this study was to investigate the effect of hydrogen peroxide (HP) and carbamide peroxide (CP) on the surface roughness of five different composite resins using profilometer and scanning electron microscope (SEM). Thirty-six specimens (1 mm thick, 10 mm in diameter) of five composite resins were fabricated. Each composite group was equally divided into three subgroups as control, CP and HP. In control group, specimens were stored in daily refreshed distilled water during the 14-day testing period. In other groups, 10% HP (Opalescence Treswhite) and 10% CP (Opalescence PF) were applied and surface roughness values (Ra) of each specimen were measured with a profilometer at the end of 14 days. Additionally, SEM analysis was performed to evaluate the surface deformations of composite resins. Data were analyzed with Kruskal-Wallis and Mann-Whitney U tests. Ra values of composite groups exposed to bleaching agents were statistically higher than control group (p < 0.05). There was no significant difference between Ra values after HP and CP application within each composite group while SEM micrographs showed higher surface alterations at HP group compared to CP. Among the composite resins tested, Ceram-X Mono revealed the lowest Ra values after CP and HP applications as seen at SEM images. Home bleaching agents increased the surface roughness of all composites. Except CP applied Ceram-X mono specimens, Ra values of all composite resins evaluated in this study exceeded the critical limit of 0.2 μm. Ceram-X mono was the least affected composite material after bleaching application. SCANNING 38:277-283, 2016. © 2016 Wiley Periodicals, Inc. © Wiley Periodicals, Inc.

Scanning electron microscopy study of new bone formation following small and large defects preserved with xenografts supplemented with pamidronate-A pilot study in Fox-Hound dogs at 4 and 8 weeks.

PubMed

Lozano-Carrascal, Naroa; Satorres-Nieto, Marta; Delgado-Ruiz, Rafael; Maté-Sánchez de Val, José Eduardo; Gehrke, Sergio Alexandre; Gargallo-Albiol, Jorge; Calvo-Guirado, José Luis

2017-01-01

The aim of the present study was to evaluate the feasibility of SEM and EDX microanalysis on evaluating the effect of porcine xenografts (MP3 ® ) supplemented with pamidronate during socket healing. Mandibular second premolars (P2) and first molars (M1) were extracted from six Beagle dogs. P2 were categorized as small defects (SD) and M1 as large defects (LD). Four random groups were created: SC (small control defects with MP3 ® ), ST (small test defects MP3 ® +pamidronate), LC (large control defects with MP3 ® ), and LT (large test defects MP3 ® +pamidronate). At four and eight weeks of healing the samples were evaluated fisically through scanning electron microscopy (SEM), and chemical element mapping was carried out by Energy dispersive X-ray spectroscopy (EDX). After four weeks of healing, SEM and EDX analysis revealed more mineralized bone in ST and LT groups compared with control groups (p<0.05). After eight weeks, Ca/P ratios were slightly higher for small defects (groups SC and ST); in SEM description, in both control and test groups, trabecular bone density was similar to the adjacent mineralized cortical bone. Within the limitations of this experimental study, SEM description and EDX elemental microanalysis have demonstrated to be useful techniques to assess bone remodelling of small and large defects. Both techniques show increased bone formation in test groups (MP3 ® modified with pamidronate) after four and eight weeks of healing. Copyright © 2016 Elsevier GmbH. All rights reserved.

Comparative Study of Esophageal Self-expandable Metallic Stent Insertion and Gastrostomy Feeding for Dysphagia Caused by Lung Cancer.

PubMed

Kim, Jihye; Min, Yang Won; Lee, Hyuk; Min, Byung Hoon; Lee, Joon Haeng; Rhee, Poong Lyul; Kim, Jae J

2018-03-25

Dysphagia is encountered in a large proportion of patients with lung cancer and is associated with malnutrition and a poor quality of life. This study compared the clinical outcomes of self-expandable metallic stent (SEMS) insertion and percutaneous gastrostomy (PG) feeding for patients with lung cancer and dysphagia. A total of 261 patients with lung cancer, who underwent either SEMS insertion (stent group) or PG (gastrostomy group) as an initial treatment procedure for dysphagia between July 1997 and July 2015 at the Samsung Medical Center, were reviewed retrospectively, and 84 patients with esophageal obstruction were identified. The clinical outcomes, including the overall survival, additional intervention, complications, and post-procedural nutritional status in the two groups, were compared. Among the 84 patients finally analyzed, 68 patients received SEMS insertion and 16 had PG. The stent group had less cervical obstruction and more mid-esophageal obstruction than the gastrostomy group. The Kaplan-Meier curves revealed similar overall survival in the two groups. Multivariate analysis showed that the two modalities had similar survival rates (PG compared with SEMS insertion, hazard ratio 0.682, p=0.219). Fifteen patients (22.1%) in the stent group received additional intervention, whereas there was no case in the gastrostomy group (p=0.063). The decrease in the serum albumin level after the procedure was lower in the gastrostomy group than in the stent group (-0.20±0.54 g/dL vs. -0.65±0.57 g/dL, p=0.013). SEMS insertion and PG feeding for relieving dysphagia by lung cancer had a comparable survival outcome. On the other hand, PG was associated with a better nutritional status.

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.

Viewing Integrated-Circuit Interconnections By SEM

NASA Technical Reports Server (NTRS)

Lawton, Russel A.; Gauldin, Robert E.; Ruiz, Ronald P.

1990-01-01

Back-scattering of energetic electrons reveals hidden metal layers. Experiment shows that with suitable operating adjustments, scanning electron microscopy (SEM) used to look for defects in aluminum interconnections in integrated circuits. Enables monitoring, in situ, of changes in defects caused by changes in temperature. Gives truer picture of defects, as etching can change stress field of metal-and-passivation pattern, causing changes in defects.

Development of uncertainty-based work injury model using Bayesian structural equation modelling.

PubMed

Chatterjee, Snehamoy

2014-01-01

This paper proposed a Bayesian method-based structural equation model (SEM) of miners' work injury for an underground coal mine in India. The environmental and behavioural variables for work injury were identified and causal relationships were developed. For Bayesian modelling, prior distributions of SEM parameters are necessary to develop the model. In this paper, two approaches were adopted to obtain prior distribution for factor loading parameters and structural parameters of SEM. In the first approach, the prior distributions were considered as a fixed distribution function with specific parameter values, whereas, in the second approach, prior distributions of the parameters were generated from experts' opinions. The posterior distributions of these parameters were obtained by applying Bayesian rule. The Markov Chain Monte Carlo sampling in the form Gibbs sampling was applied for sampling from the posterior distribution. The results revealed that all coefficients of structural and measurement model parameters are statistically significant in experts' opinion-based priors, whereas, two coefficients are not statistically significant when fixed prior-based distributions are applied. The error statistics reveals that Bayesian structural model provides reasonably good fit of work injury with high coefficient of determination (0.91) and less mean squared error as compared to traditional SEM.

SEM method for direct visual tracking of nanoscale morphological changes of platinum based electrocatalysts on fixed locations upon electrochemical or thermal treatments.

PubMed

Zorko, Milena; Jozinović, Barbara; Bele, Marjan; Hodnik, Nejc; Gaberšček, Miran

2014-05-01

A general method for tracking morphological surface changes on a nanometer scale with scanning electron microscopy (SEM) is introduced. We exemplify the usefulness of the method by showing consecutive SEM images of an identical location before and after the electrochemical and thermal treatments of platinum-based nanoparticles deposited on a high surface area carbon. Observations reveal an insight into platinum based catalyst degradation occurring during potential cycling treatment. The presence of chloride clearly increases the rate of degradation. At these conditions the dominant degradation mechanism seems to be the platinum dissolution with some subsequent redeposition on the top of the catalyst film. By contrast, at the temperature of 60°C, under potentiostatic conditions some carbon corrosion and particle aggregation was observed. Temperature treatment simulating the annealing step of the synthesis reveals sintering of small platinum based composite aggregates into uniform spherical particles. The method provides a direct proof of induced surface phenomena occurring on a chosen location without the usual statistical uncertainty in usual, random SEM observations across relatively large surface areas. Copyright © 2014 Elsevier B.V. All rights reserved.

Preliminary SEM Observations on the Surface of Elastomeric Impression Materials after Immersion or Ozone Disinfection

PubMed Central

Prombonas, Anthony; Yannikakis, Stavros; Karampotsos, Thanasis; Katsarou, Martha-Spyridoula; Drakoulis, Nikolaos

2016-01-01

Introduction Surface integrity of dental elastomeric impression materials that are subjected to disinfection is of major importance for the quality of the final prosthetic restorations. Aim The aim of this qualitative Scanning Electronic Microscopy (SEM) study was to reveal the effects of immersion or ozone disinfection on the surface of four dental elastomeric impression materials. Materials and Methods Four dental elastomeric impression material brands were used (two vinyl polysiloxane silicones, one polyether, and one vinyl polyether silicone). Total of 32 specimens were fabricated, eight from each impression material. Specimens were immersion (0.525% sodium hypochlorite solution or 0.3% benzalkonium chloride solution) or ozone disinfected or served as controls and examined with SEM. Results Surface degradation was observed on several speci-mens disinfected with 0.525% sodium hypochlorite solution. Similar wavy-wrinkling surface structures were observed in almost all specimens, when treated either with 0.3% benzalkonium chloride solution or ozone. Conclusion The SEM images obtained from this study revealed that both immersion disinfectants and ozone show similar impression material surface alterations. Ozone seems to be non-inferior as compared to immersion disinfectants, but superior as to environmental protection. PMID:28208993

The molecular identification of Streptococcus equi subsp. equi strains isolated within New Zealand.

PubMed

Patty, O A; Cursons, R T M

2014-03-01

To identify Streptococcus equi subsp. equi (S. equi) by PCR analysis and obtain isolates by culture, in order to investigate the strains of S. equi infecting horses within New Zealand. A diagnostic PCR, based on the amplification of the seeI gene for S. equi, was used on 168 samples submitted from horses with and without clinical signs of strangles. Samples were also processed and cultured on selective media for the isolation of β-haemolytic colonies. In addition, the hypervariable region of the seM gene of S. equi was amplified and then sequenced for strain typing purposes. Of the 168 samples, 35 tested positive for S. equi using PCR. Thirty-two confirmed samples were from horses with a clinical diagnosis of strangles and three were from horses where clinical information was unavailable. Only 22/35 (63%) confirmed S. equi samples were successfully isolated following culture. Strain typing demonstrated that two novel seM alleles of S. equi were found in New Zealand with SeM-99 strains being restricted to the North Island while SeM-100 strains were found in both North and South Islands. The application of PCR for the laboratory confirmation of strangles allowed for a rapid and sensitive identification of S. equi. Moreover, seM typing revealed that within the samples examined two strains of S. equi co-circulated within the North Island of New Zealand but only one strain in the South Island. PCR reduces the time required to obtain laboratory confirmation of strangles compared with culture methods. It also has greater sensitivity in detecting S. equi infections, which is of particular importance in the detection of carrier animals which normally shed low numbers of bacteria. Additionally, seM molecular typing can differentiate between bacterial strains, assisting in the monitoring of local strains of S. equi subsp. equi causing disease.

Impedance spectroscopy of the oxide films formed during high temperature oxidation of a cobalt-plated ferritic alloy

NASA Astrophysics Data System (ADS)

Velraj, S.; Zhu, J. H.; Painter, A. S.; Du, S. W.; Li, Y. T.

2014-02-01

Impedance spectroscopy was used to evaluate the oxide films formed on cobalt-coated Crofer 22 APU ferritic stainless steel after thermal oxidation at 800 °C in air for different times (i.e. 2, 50, 100 and 500 h). Impedance spectra of the oxide films exhibited two or three semicircles depending on the oxidation time, which correspond to the presence of two or three individual oxide layers. Coupled with scanning electron microscopy/energy-dispersive spectroscopy (SEM/EDS) and X-ray diffraction (XRD), the individual oxide layer corresponding to each semicircle was determined unambiguously. Impedance spectrum analysis of the oxide films formed on the sample after thermal exposure at 800 °C in air for 2 h led to the identification of the low-frequency and high-frequency semicircles as being from Cr2O3 and Co3O4, respectively. SEM/EDS and XRD analysis of the 500-h sample clearly revealed the presence of three oxide layers, analyzed to be Co3-xCrxO4, CoCr2O4, and Cr2O3. Although the SEM images of the 50-h and 100-h samples did not clearly show the CoCr2O4 layer, impedance plots implied their presence. The oxide scales were assigned to their respective semicircles and the electrical properties of Co3-xCrxO4, CoCr2O4 and Cr2O3 were determined from the impedance data.

Elemental composition study of heavy metal (Ni, Cu, Zn) in riverbank soil by electrokinetic-assisted phytoremediation using XRF and SEM/EDX

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

Jamari, Suhailly; Embong, Zaidi; Bakar, Ismail

Electrokinetic (EK)-assisted phytoremediation is one of the methods that have a big potential in enhancing the ability of plant uptake in soils remediation process. This research was conducted to investigate the difference in elemental composition concentration of riverbank soil and the change of pH between pre- and post-phytoremediation under the following condition: 1) control or as-receive sample; 2) Dieffenbachia spp plant with EK system (a pair of EK electrodes connected to a direct current (DC) power supply). After the electrodes were connected to a magnitude of 6V/cm{sup −1} electric field for 4 hours/day, the soil and plant samples were analyzedmore » using and X-ray Fluorescence Spectrometer (XRF) and Scanning Electron Microscope / Energy Dispersive X-ray Spectroscopy (SEM/EDX). The SEM/EDX analysis showed that concentration of elemental composition (Ni, Cu and Zn) in post-phytoremediation plant powder samples had increase while elemental concentrations in the post-phytoremediation soil samples were decreased. XRF analysis presented a variation in soil elemental composition concentration from anode to cathode where the concentration near anode region increased while decreased near the cathode region. A significant changes in soil pH were obtained where the soil pH increase in cathode region while decrease in anode region. The results reveal that the assistance of EK in phytoremediation process has increase the efficiency of plant uptake.« less

Using structural equation modeling for network meta-analysis.

PubMed

Tu, Yu-Kang; Wu, Yun-Chun

2017-07-14

Network meta-analysis overcomes the limitations of traditional pair-wise meta-analysis by incorporating all available evidence into a general statistical framework for simultaneous comparisons of several treatments. Currently, network meta-analyses are undertaken either within the Bayesian hierarchical linear models or frequentist generalized linear mixed models. Structural equation modeling (SEM) is a statistical method originally developed for modeling causal relations among observed and latent variables. As random effect is explicitly modeled as a latent variable in SEM, it is very flexible for analysts to specify complex random effect structure and to make linear and nonlinear constraints on parameters. The aim of this article is to show how to undertake a network meta-analysis within the statistical framework of SEM. We used an example dataset to demonstrate the standard fixed and random effect network meta-analysis models can be easily implemented in SEM. It contains results of 26 studies that directly compared three treatment groups A, B and C for prevention of first bleeding in patients with liver cirrhosis. We also showed that a new approach to network meta-analysis based on the technique of unrestricted weighted least squares (UWLS) method can also be undertaken using SEM. For both the fixed and random effect network meta-analysis, SEM yielded similar coefficients and confidence intervals to those reported in the previous literature. The point estimates of two UWLS models were identical to those in the fixed effect model but the confidence intervals were greater. This is consistent with results from the traditional pairwise meta-analyses. Comparing to UWLS model with common variance adjusted factor, UWLS model with unique variance adjusted factor has greater confidence intervals when the heterogeneity was larger in the pairwise comparison. The UWLS model with unique variance adjusted factor reflects the difference in heterogeneity within each comparison. SEM provides a very flexible framework for univariate and multivariate meta-analysis, and its potential as a powerful tool for advanced meta-analysis is still to be explored.

Green synthesis of silver nanoparticles using tannins

NASA Astrophysics Data System (ADS)

Raja, Pandian Bothi; Rahim, Afidah Abdul; Qureshi, Ahmad Kaleem; Awang, Khalijah

2014-09-01

Colloidal silver nanoparticles were prepared by rapid green synthesis using different tannin sources as reducing agent viz. chestnut (CN), mangrove (MG) and quebracho (QB). The aqueous silver ions when exposed to CN, MG and QB tannins were reduced which resulted in formation of silver nanoparticles. The resultant silver nanoparticles were characterized using UV-Visible, X-ray diffraction (XRD), scanning electron microscopy (SEM/EDX), and transmission electron microscopy (TEM) techniques. Furthermore, the possible mechanism of nanoparticles synthesis was also derived using FT-IR analysis. Spectroscopy analysis revealed that the synthesized nanoparticles were within 30 to 75 nm in size, while XRD results showed that nanoparticles formed were crystalline with face centered cubic geometry.

Chemical route for formation of intermetallic Zn 4Sb 3 phase

NASA Astrophysics Data System (ADS)

Denoix, A.; Solaiappan, A.; Ayral, R. M.; Rouessac, F.; Tedenac, J. C.

2010-05-01

Synthesis of intermetallic zinc antimonide phases via low temperature solution route was investigated. Trial experiments were carried out under inert atmosphere at 70 °C using metallic Zn, SbCl 3 and NaBH 4 as reactants and tetrahydrofuran (THF), dimethylsulfoxide (DMSO) as organic media. Powder X-ray analysis confirmed the nucleation and growth of ZnSb phases in presence of excess Zn. SEM analysis revealed the existence of core-shell structure comprising of Zn core and Sb shell. Such particles get transformed into Zn 4Sb 3 crystalline phases upon thermal treatment at 300 °C/6 h in a silica tube closed under high secondary vacuum.

Molecularly imprinted nanopatterns for the recognition of biological warfare agent ricin.

PubMed

Pradhan, Santwana; Boopathi, M; Kumar, Om; Baghel, Anuradha; Pandey, Pratibha; Mahato, T H; Singh, Beer; Vijayaraghavan, R

2009-11-15

Molecularly imprinted polymer (MIP) for biological warfare agent (BWA) ricin was synthesized using silanes in order to avoid harsh environments during the synthesis of MIP. The synthesized MIP was utilized for the recognition of ricin. The complete removal of ricin from polymer was confirmed by fluorescence spectrometer and SEM-EDAX. SEM and EDAX studies confirmed the attachment of silane polymer on the surface of silica gel matrix. SEM image of Ricin-MIP exhibited nanopatterns and it was found to be entirely different from the SEM image of non-imprinted polymer (NIP). BET surface area analysis revealed more surface area (227 m(2)/g) for Ricin-MIP than that of NIP (143 m(2)/g). In addition, surface area study also showed more pore volume (0.5010 cm(3)/g) for Ricin-MIP than that of NIP (0.2828 cm(3)/g) at 12 nm pore diameter confirming the presence of imprinted sites for ricin as the reported diameter of ricin is 12 nm. The recognition and rebinding ability of the Ricin-MIP was tested in aqueous solution. Ricin-MIP rebound more ricin when compared to the NIP. Chromatogram obtained with Ricin-MIP exhibited two peaks due to imprinting, however, chromatogram of NIP exhibited only one peak for free ricin. SDS-PAGE result confirmed the second peak observed in chromatogram of Ricin-MIP as ricin peak. Ricin-MIP exhibited an imprinting efficiency of 1.76 and it also showed 10% interference from the structurally similar protein abrin.

The internalization of posterior subcapsular cataracts (PSCs) in Royal College of Surgeons (RCS) rats. II. The inter-relationship of optical quality and structure as a function of age.

PubMed

Kuszak, J R; Al-Ghoul, K J; Novak, L A; Peterson, K L; Herbert, K L; Sivak, J G

1999-05-06

The Royal College of Surgeons (RCS) rat is an animal model for human retinal degenerative disease and posterior subcapsular cataracts (PSCs). The purpose of this study was to correlate the structure and optical quality of RCS lenses with PSCs as a function of their internalization, with normal, non-cataractous, age-matched control lenses. Correlative light (LM), scanning electron microscopic (SEM), three-dimensional computer assisted drawings (3D-CADs) and low power helium-neon laser scan analysis were used to examine the structure and function of lenses. The optical properties (average focal length variability; sharpness of focus) of RCS rat lenses are quantitatively compromised by PSCs. Correlative LM and SEM analysis of RCS lenses at various stages of PSC internalization (1.5, 3, 6, 9, 12 and 15 months of age), revealed that the sutures formed by additional fiber growth were progressively more abnormal. During PSC internalization, two to nine small suture branches were formed and arranged in modified line to multiple y configurations rather than the normal three branch y sutures. These temporal changes were also chronicled in animated 3D-CAD videos derived from lens reconstructions based on LM and SEM micrographs from the selected time points stated above. However, laser scan analysis also revealed that as the PSCs of RCS rat lenses were progressively internalized, there was a steady improvement in total sharpness of focus that reached normal levels by 12 months of age. The correlation of laser scan and structural data from specific regions of lenses revealed the following: 1. The abnormal posterior sutures of RCS rats with internalized PSCs effect a greater reduction in optical quality than normal posterior sutures of age-matched controls; 2. However, the resulting abnormal suture plane area was cumulatively similar to that of age-matched controls; 3. Thus, total optical quality was similar between RCS lenses with internalized PSCs and age-matched controls by 12 months of age. The results of this study show that RCS lenses with internalized PSCs can appear grossly, and indeed optically perform, at levels comparable to aged lenses. These findings are consistent with clinical observations of spontaneous recovery from PSC. The results suggest that human PSCs that occur as a consequence of retinal degenerative disease could also be the result of abnormal posterior suture growth. If this is proven to be the case, such PSCs may have some capacity for repair or recovery thereby obviating their surgical removal.

Characterization of Sweetmeat Waste and Its Suitability for Sorption of As(III) in Aqueous Media.

PubMed

Islam, Md Mirajul; Adak, Asok; Paul, Prabir K

2017-04-01

  Presence of arsenic in effluents from mining, mineral processing, and metal plating industries pose a serious health hazard to human beings. In this research, suitability of cheap sweetmeat waste (SMW), which is sweet industry byproduct, was investigated for the treatment of As(III). The physicochemical properties of the sorbent were characterized. The SEM images revealed highly heterogeneous sorbent surface. XRD analysis showed the presence of different polysaccharides mainly containing hydroxyl functional group. FTIR analysis was also performed to confirm the functional groups present in the sorbent. Batch experiments were conducted for kinetic analysis, effect of initial As(III) concentration, sorbent dose, electrolytes, pH, and temperature in order to understand sorption behavior. Presence of electrolyte, solution pH, and temperature were found to affect the performance of the sorbent. The sorption followed pseudo-second order reaction and Langmuir isotherm model best. The studies revealed SMW to be an efficient media for removal of As(III) from aqueous environment.

SHI induced modification in structural, optical, dielectric and thermal properties of poly ethylene oxide films

NASA Astrophysics Data System (ADS)

Patel, Gnansagar B.; Bhavsar, Shilpa; Singh, N. L.; Singh, F.; Kulriya, P. K.

2016-07-01

Poly ethylene oxide (PEO) films were synthesized by solution cast method. These self-standing films were exposed with 60 MeV C+5 ion and 100 MeV Ni+7 ion at different fluences. SHI induced effect was investigated by employing various techniques. The crystalline size decreased upon irradiation as observed from XRD analysis. FTIR analysis reveals the decrement in the peak intensity upon irradiation. Tauc's method was used to determine the optical band gap (Eg), which shows decreasing trends with increase of fluence. The dielectric properties were investigated in the frequency range 10 Hz to 10 MHz for unirradiated and irradiated films. The dielectric constant remains same for the broad-spectrum of frequency and increases at lower frequency. The dielectric loss also moderately influence as a function of frequency due to irradiation. DSC analysis validated the results of XRD. Scanning electron microscopy (SEM) reveals that there is significant change in the surface morphology due to irradiation.

Optimization of SEM-EDS to determine the C–A–S–H composition in matured cement paste samples

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

Rossen, J.E., E-mail: john.rossen@alumni.epfl.ch

Microanalysis of characteristic X-rays in the SEM is a powerful method to assess the chemical composition of phases in cement pastes, in particular the calcium silicate hydrate containing aluminium (C–A–S–H). Nevertheless, many variables may influence the results obtained, due mainly to the intimate mixing of C–A–S–H with other hydrate phases and the susceptibility of this phase to damage by the electron beam. In this study the effect of various acquisition parameters was examined, along with methods to determine an “average” C–A–S–H composition. The results acquired in the SEM were compared with the analysis of the same samples in the TEM,more » where phases can be analyzed without intermixing. A simple method was used to obtain compositions from SEM based analysis that are very close to those which can be obtained in the TEM. - Highlights: •The intermixing of phases is the limiting factor in the analysis of C–A–S–H composition by SEM-EDS •Guidelines to limit beam damage and properly analyze C–A–S–H composition by SEM-EDS are given •SEM-EDS and TEM-EDS give similar results when proper data treatment is made.« less

Novel synthesis and structural analysis of zinc oxide nanoparticles for the non enzymatic glucose biosensor.

PubMed

Dayakar, T; Venkateswara Rao, K; Bikshalu, K; Rajendar, V; Park, Si-Hyun

2017-06-01

A non-enzymatic glucose biosensor was developed by utilizing the zinc oxide nanoparticles (ZnO NPs) synthesized by a novel green method using the leaf extract of Ocimum tenuiflorum. The structural, optical and morphological properties of ZnO NPs characterized by means of X-ray diffraction (XRD), ultraviolet-visible (UV-vis) spectroscopy, Fourier transform infrared (FTIR) spectroscopy, scanning electron microscopy (SEM), energy-dispersive X-ray (EDAX) spectroscopy, and transmission electron microscopy (TEM). The XRD analysis revealed that the ZnO NPs were crystalline and had a hexagonal wurtzite structure. The crystallite size measured by XRD was the same as that measured using SEM and TEM. The UV-vis absorption spectrum estimates the band gap of ZnO NPs present in the range of 2.82 to 3.45eV. The reduction and formation of ZnO NPs mainly due to the involvement of leaf extract bio-molecular compounds analyzed from the FTIR spectra. The SEM result confirms the morphology of the NPs responsible from the various concentration of leaf extract in the synthesis process. HRTEM analysis depicts the spherical structure of ZnO NPs. The synthesized NPs have the average size ranges from 10 to 20nm. The fabricated GCE/ZnO glucose sensor represents superior electro catalytic activity that has been observed for ZnO NPs with a reproducible sensitivity of 631.30μAmM -1 cm -2 , correlation coefficient of R=0.998, linear dynamic range from 1-8.6mM, low detection limit of 0.043μM (S/N=3) and response time<4s. Copyright © 2017 Elsevier B.V. All rights reserved.

Nondestructive SEM for surface and subsurface wafer imaging

NASA Technical Reports Server (NTRS)

Propst, Roy H.; Bagnell, C. Robert; Cole, Edward I., Jr.; Davies, Brian G.; Dibianca, Frank A.; Johnson, Darryl G.; Oxford, William V.; Smith, Craig A.

1987-01-01

The scanning electron microscope (SEM) is considered as a tool for both failure analysis as well as device characterization. A survey is made of various operational SEM modes and their applicability to image processing methods on semiconductor devices.

Human bloodstains on bone artefacts: an SEM intra- and inter-sample comparative study using ratite bird tibiotarsus.

PubMed

Hortolà, Policarp

2016-11-01

Apart from their forensic significance in crime investigation, human bloodstains have an anthropological interest due to their occurrence on certain traditional weapons and ritual objects. Previously, a guiding study of erythrocytes in experimental samples including domestic sheep (Ovis aries) tibia was carried out using a scanning electron microscope (SEM). Here, a comparative SEM study to reveal the potential differences in bloodstain surface morphology as a function of intra-sample (smear region) and inter-sample (individual smear, smearing mechanism, bone origin) parameters is reported. A fragment of emu (Dromaius novaehollandiae) tibiotarsus was smeared with an adult man's peripheral blood. After air-drying and storing indoors, the boundary and neighbouring inner areas of the three individual bloodstains obtained were examined via secondary electrons in a variable-pressure SEM working in low-vacuum mode. As a whole, desiccation microcracks were present, the limits between the smear and the substrate appeared poorly defined, and no erythrocyte negative replicas were observed in the examined areas. In addition, a putative fibrin network, more or less embedded in the dried plasma matrix, was observed in the smears' boundary. Regarding the smear region in sliding smears, the periphery and boundary revealed to be different, while the head and tail were similar. Considering individual sliding smears, they had similar characteristics. Relating to the smear region as a function of the smearing mechanism, the periphery was different whether sliding or touching, while the boundary was similar in sliding and touching smears. Concerning the smear region as a function of the bone origin, the periphery revealed to be similar in both ratite and mammalian bone, while the boundary did different in ratite and mammalian bone. The results of this study show that SEM examination can be used fruitfully to detect bloodstains on ratite bone. Combined with previous SEM results in domestic sheep bone, they suggest, further, that blood remains can be detected on objects made of bone irrespectively of the mammalian or ratite origin of this raw material. Copyright © 2016 Elsevier Ltd. All rights reserved.

Fabrication of mesoporous cerium dioxide films by cathodic electrodeposition.

PubMed

Kim, Young-Soo; Lee, Jin-Kyu; Ahn, Jae-Hoon; Park, Eun-Kyung; Kim, Gil-Pyo; Baeck, Sung-Hyeon

2007-11-01

Mesoporous cerium dioxide (Ceria, CeO2) thin films have been successfully electrodeposited onto ITO-coated glass substrates from an aqueous solution of cerium nitrate using CTAB (Cetyltrimethylammonium Bromide) as a templating agent. The synthesized films underwent detailed characterizations. The crystallinity of synthesized CeO2 film was confirmed by XRD analysis and HR-TEM analysis, and surface morphology was investigated by SEM analysis. The presence of mesoporosity in fabricated films was confirmed by TEM and small angle X-ray analysis. As-synthesized film was observed from XRD analysis and HR-TEM image to have well-crystallized structure of cubic phase CeO2. Transmission electron microscopy and small angle X-ray analysis revealed the presence of uniform mesoporosity with a well-ordered lamellar phase in the CeO2 films electrodeposited with CTAB templating.

Cryo-Scanning Electron Microscopy (SEM) and Scanning Transmission Electron Microscopy (STEM)-in-SEM for Bio- and Organo-Mineral Interface Characterization in the Environment.

PubMed

Wille, Guillaume; Hellal, Jennifer; Ollivier, Patrick; Richard, Annie; Burel, Agnes; Jolly, Louis; Crampon, Marc; Michel, Caroline

2017-12-01

Understanding biofilm interactions with surrounding substratum and pollutants/particles can benefit from the application of existing microscopy tools. Using the example of biofilm interactions with zero-valent iron nanoparticles (nZVI), this study aims to apply various approaches in biofilm preparation and labeling for fluorescent or electron microscopy and energy dispersive X-ray spectrometry (EDS) microanalysis for accurate observations. According to the targeted microscopy method, biofilms were sampled as flocs or attached biofilm, submitted to labeling using 4',6-diamidino-2-phenylindol, lectins PNA and ConA coupled to fluorescent dye or gold nanoparticles, and prepared for observation (fixation, cross-section, freezing, ultramicrotomy). Fluorescent microscopy revealed that nZVI were embedded in the biofilm structure as aggregates but the resolution was insufficient to observe individual nZVI. Cryo-scanning electron microscopy (SEM) observations showed nZVI aggregates close to bacteria, but it was not possible to confirm direct interactions between nZVI and cell membranes. Scanning transmission electron microscopy in the SEM (STEM-in-SEM) showed that nZVI aggregates could enter the biofilm to a depth of 7-11 µm. Bacteria were surrounded by a ring of extracellular polymeric substances (EPS) preventing direct nZVI/membrane interactions. STEM/EDS mapping revealed a co-localization of nZVI aggregates with lectins suggesting a potential role of EPS in nZVI embedding. Thus, the combination of divergent microscopy approaches is a good approach to better understand and characterize biofilm/metal interactions.

Fabrication and physical-chemical characterisation of polyelectrolyte microparticles: platform for controlled release of bioactives.

PubMed

Sun, Yuhui; Travas-Sejdic, Jadranka; Wen, Jingyuan; Alany, Raid G

2009-08-01

Porous CaCO(3) microparticles were fabricated by colloidal crystallization. Two oppositely charged polyelectrolytes, poly (styrene sulfonate, PSS) and poly (allylamine hydrochloride, PAH) were adsorbed layer-by-layer on the CaCO(3) templates. Polyelectrolyte microcapsules were then obtained by removing the CaCO(3) core. Scanning electron microscopy (SEM), energy-dispersion X-ray analysis (EDX), laser diffraction particle sizing and Raman spectroscopy were employed to characterize the physico-chemical properties of the constructed microcapsules. In vitro drug release studies were conducted using the model water-soluble drug Rhodamine B. Factors such as the number of polyelectrolyte layers and pH were investigated. SEM micrographs revealed uniform CaCO(3) microparticles, nearly spherical in shape with pronounced surface roughness, and highly developed interior porous structure. The surface of polyelectrolyte coated particles became rougher than the initial CaCO(3) microparticles. The acquired SEM micrographs of the (PSS/PAH)(n) microcapsules indicated that the number of layers affected the morphology of the microcapsules. The (PSS/PAH)(3) microcapsules revealed a very porous network with many holes resembling the initial morphology of CaCO(3) microparticles. Raman spectra showed peaks at 1125 cm(-1) (S=O bond) and 1600 cm(-1) (aromatic ring stretching) which represented the PSS molecule. The thickness of each layer was about 10 to 20 nm and it can be tailored to such nanometer level by controlling the number of adsorbed layers. The in vitro release of Rhodamine B was dependent on both the number of wall bilayers as well as the pH of the release media. These systems provide an opportunity for the development of controlled release dosage forms with greater effectiveness in the treatment of chronic conditions.

Effect of cadmium incorporation on the properties of zinc oxide thin films

NASA Astrophysics Data System (ADS)

Bharath, S. P.; Bangera, Kasturi V.; Shivakumar, G. K.

2018-02-01

Cd x Zn1- x O (0 ≤ x ≤ 0.20) thin films are deposited on soda lime glass substrates using spray pyrolysis technique. To check the thermal stability, Cd x Zn1- x O thin films are subjected to annealing. Both the as-deposited and annealed Cd x Zn1- x O thin films are characterized using X-ray diffraction (XRD), scanning electron microscope (SEM) and energy-dispersive X-ray analysis (EDAX) to check the structural, surface morphological and compositional properties, respectively. XRD analysis reveals that the both as-deposited and annealed Cd x Zn1- x O thin films are (002) oriented with wurtzite structure. SEM studies confirm that as-deposited, as well as annealed Cd x Zn1- x O thin films are free from pinholes and cracks. Compositional analysis shows the deficiency in Cd content after annealing. Optical properties evaluated from UV-Vis spectroscopy shows red shift in the band gap for Cd x Zn1- x O thin films. Electrical property measured using two probe method shows a decrease in the resistance after Cd incorporation. The results indicate that cadmium can be successfully incorporated in zinc oxide thin films to achieve structural changes in the properties of films.

Synthesis, characterization and cytotoxicity of rare earth metal ion complexes of N,N‧-bis-(2-thiophenecarboxaldimine)-3,3‧-diaminobenzidene, Schiff base ligand

NASA Astrophysics Data System (ADS)

Shakir, Mohammad; Abbasi, Ambreen; Faraz, Mohammad; Sherwani, Asif

2015-12-01

Lanthanide complexes of La3+, Pr3+, Nd3+, Gd3+, Er3+ of general formula [Ln2 L(H2O)4(NO3)4](NO3)2·2H2O have been synthesized from Schiff base, N,N‧-bis-(2-thiophenecarboxaldimine)-3,3‧-diaminobenzidene. The complexes were characterized by elemental analysis, molar conductance, UV-Vis, fluorescence, FT-IR,1H NMR, mass spectroscopy, EDX, SEM and thermal analysis. FT-IR spectral data suggested that ligand coordinate with metal ions through azomethine nitrogen and uncondensed amino group. Molar conductance data revealed 1:2 electrolytic nature of complexes. From the analytical data, the stoichiometry of the complexes was found to be 1:2 (ligand:metal). Thephysico-chemical data suggested eight coordination number for Ln(III)Schiffbase complexes. SEM analysis shows morphological changes in the surfaces of complexes as compared to free ligand. Thermal decomposition profiles were consistent with proposed formulations. The anticancer activity of the complexes and theSchiffbase ligand has been studied towards human cervical cancer celllines (HeLa) and human breast cancer cell lines (MCF-7) and it was found that complexes exhibited greater activity than theSchiffbase.

Quantifying grain shape with MorpheoLV: A case study using Holocene glacial marine sediments

NASA Astrophysics Data System (ADS)

Charpentier, Isabelle; Staszyc, Alicia B.; Wellner, Julia S.; Alejandro, Vanessa

2017-06-01

As demonstrated in earlier works, quantitative grain shape analysis has revealed to be a strong proxy for determining sediment transport history and depositional environments. MorpheoLV, devoted to the calculation of roughness coefficients from pictures of unique clastic sediment grains using Fourier analysis, drives computations for a collection of samples of grain images. This process may be applied to sedimentary deposits assuming core/interval/image archives for the storage of samples collected along depth. This study uses a 25.8 m jumbo piston core, NBP1203 JPC36, taken from a 100 m thick sedimentary drift deposit from Perseverance Drift on the northern Antarctic Peninsula continental shelf. Changes in ocean and ice conditions throughout the Holocene recorded in this sedimentary archive can be assessed by studying grain shape, grain texture, and other proxies. Ninety six intervals were sampled and a total of 2319 individual particle images were used. Microtextures of individual grains observed by SEM show a very high abundance of authigenically precipitated silica that obscures the original grain shape. Grain roughness, computed along depth with MorpheoLV, only shows small variation confirming the qualitative observation deduced from the SEM. Despite this, trends can be seen confirming the reliability of MorpheoLV as a tool for quantitative grain shape analysis.

MALDI-TOF mass spectrometry imaging reveals molecular level changes in ultrahigh molecular weight polyethylene joint implants in correlation with lipid adsorption.

PubMed

Fröhlich, Sophie M; Archodoulaki, Vasiliki-Maria; Allmaier, Günter; Marchetti-Deschmann, Martina

2014-10-07

Ultrahigh molecular weight polyethylene (PE-UHMW), a material with high biocompatibility and excellent mechanical properties, is among the most commonly used materials for acetabular cup replacement in artificial joint systems. It is assumed that the interaction with synovial fluid in the biocompartment leads to significant changes relevant to material failure. In addition to hyaluronic acid, lipids are particularly relevant for lubrication in an articulating process. This study investigates synovial lipid adsorption on two different PE-UHMW materials (GUR-1050 and vitamin E-doped) in an in vitro model system by matrix-assisted laser desorption/ionization time-of-flight (MALDI-TOF) mass spectrometry imaging (MSI). Lipids were identified by high performance thin layer chromatography (HP-TLC) and tandem mass spectrometry (MS/MS) analysis, with an analytical focus on phospholipids and cholesterol, both being species of high importance for lubrication. Scanning electron microscopy (SEM) analysis was applied in the study to correlate molecular information with PE-UHMW material qualities. It is demonstrated that lipid adsorption preferentially occurs in rough or oxidized polymer regions. Polymer modifications were colocalized with adsorbed lipids and found with high density in regions identified by SEM. Explanted, the in vivo polymer material showed comparable and even more obvious polymer damage and lipid adsorption when compared with the static in vitro model. A three-dimensional reconstruction of MSI data from consecutive PE-UHMW slices reveals detailed information about the diffusion process of lipids in the acetabular cup and provides, for the first time, a promising starting point for future studies correlating molecular information with commonly used techniques for material analysis (e.g., Fourier-transform infrared spectroscopy, nanoindentation).

Pore Structure Characterization of Sodium Hydroxide Activated Slag Using Mercury Intrusion Porosimetry, Nitrogen Adsorption, and Image Analysis.

PubMed

Zuo, Yibing; Ye, Guang

2018-06-19

The pore structure of alkali-activated slag has a significant influence on its performance. However, the literature shows insufficient studies regarding the suitability of different techniques for characterizing the pore structure and the influences of Na₂O and curing age on pore structure development. In pursuit of a better understanding, the pore structure of sodium hydroxide activated slag paste was characterized by multiple techniques, e.g., mercury intrusion porosimetry (MIP), nitrogen (N₂) adsorption, and scanning electron microscopy (SEM) image analysis. The sodium hydroxide activated slag pastes were prepared with three different contents of Na₂O (Na₂O/slag = 4, 6, and 8%) and cured for different times up to 360 days. The microstructure observation reveals that outer C⁻(N⁻)A⁻S⁻H and inner C⁻(N⁻)A⁻S⁻H grow successively around the reacting slag grains, along with crystalline reaction products which are formed in the empty coarse pore space. The increase of Na₂O content and curing age lead to a finer pore structure. The MIP measurements show that the total porosity drops about 70% within the first day, and that one peak at most, corresponding to gel pores, was identified in the differential curves of all the investigated samples from 1 to 360 days. On the contrary, only one peak, corresponding to capillary pores, was identified by SEM-image analysis. The differential curves derived from N₂ adsorption generally reveal two peaks, and the trend that the pore diameters of those two peaks vary with curing age depends on the content of Na₂O. Compared to Portland cement, sodium hydroxide activated slag has a higher pore space filling capacity ( χ , V products / V slag-reacted ), while the capacity decreases with increasing Na₂O content and curing age.

Surface characterization of LDEF materials

NASA Astrophysics Data System (ADS)

Wightman, J. P.; Grammer, Holly Little

1993-10-01

The NASA Long Duration Exposure Facility (LDEF), a passive experimental satellite, was placed into low-Earth orbit by the Shuttle Challenger in Apr. 1984. The LDEF spent an unprecedented 69 months in space. The flight and recovery of the LDEF provided a wealth of information on the longterm space environmental effects of a variety of materials exposed to the low-Earth orbit environment. Surface characterization of LDEF materials included polymers, composites, thermal control paints, and aluminum. X-ray photoelectron spectroscopy (XPS), Auger electron spectroscopy (AES), scanning electron microscopy (SEM), and contact angle analysis were used to document changes in both the surface composition and surface chemistry of these materials. Detailed XPS analysis of the polymer systems, such as Kapton, polyimide polysiloxane copolymers, and fluorinated ethylene propylene thermal blankets on the backside of the LDEF revealed significant changes in both the surface composition and surface chemistry as a result of exposure to the low-Earth orbit environment. Polymer systems such as Kapton, polyimide polysiloxane copolymers, and polysulfone showed a common trend of decreasing carbon content and increasing oxygen content with respect to the control sample. Carbon 1s curve fit XPS analysis of the composite samples, in conjunction with SEM photomicrographs, revealed significant ablation of the polymer matrix resin to expose the carbon fibers of the composite during exposure to the space environment. Surface characterization of anodized aluminum tray clamps, which were located at regular intervals over the entire LDEF frame, provided the first results to evaluate the extent of contamination with respect to position on the LDEF. The XPS results clearly showed that the amount and state of both silicon and fluorine contamination were directly dependent upon the position of the tray clamp on the LDEF.

Surface characterization of LDEF materials

NASA Technical Reports Server (NTRS)

Wightman, J. P.; Grammer, Holly Little

1993-01-01

The NASA Long Duration Exposure Facility (LDEF), a passive experimental satellite, was placed into low-Earth orbit by the Shuttle Challenger in Apr. 1984. The LDEF spent an unprecedented 69 months in space. The flight and recovery of the LDEF provided a wealth of information on the longterm space environmental effects of a variety of materials exposed to the low-Earth orbit environment. Surface characterization of LDEF materials included polymers, composites, thermal control paints, and aluminum. X-ray photoelectron spectroscopy (XPS), Auger electron spectroscopy (AES), scanning electron microscopy (SEM), and contact angle analysis were used to document changes in both the surface composition and surface chemistry of these materials. Detailed XPS analysis of the polymer systems, such as Kapton, polyimide polysiloxane copolymers, and fluorinated ethylene propylene thermal blankets on the backside of the LDEF revealed significant changes in both the surface composition and surface chemistry as a result of exposure to the low-Earth orbit environment. Polymer systems such as Kapton, polyimide polysiloxane copolymers, and polysulfone showed a common trend of decreasing carbon content and increasing oxygen content with respect to the control sample. Carbon 1s curve fit XPS analysis of the composite samples, in conjunction with SEM photomicrographs, revealed significant ablation of the polymer matrix resin to expose the carbon fibers of the composite during exposure to the space environment. Surface characterization of anodized aluminum tray clamps, which were located at regular intervals over the entire LDEF frame, provided the first results to evaluate the extent of contamination with respect to position on the LDEF. The XPS results clearly showed that the amount and state of both silicon and fluorine contamination were directly dependent upon the position of the tray clamp on the LDEF.

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.

Antibacterial and antioxidant properties of biosynthesized zinc oxide nanoparticles from Ceropegia candelabrum L. - An endemic species

NASA Astrophysics Data System (ADS)

Murali, M.; Mahendra, C.; Nagabhushan; Rajashekar, N.; Sudarshana, M. S.; Raveesha, K. A.; Amruthesh, K. N.

2017-05-01

Zinc oxide nanoparticles (ZnO-NPs) were synthesized for the first time from any of the species of Ceropegia. Presently, ZnO-NPs were synthesized from the leaf extract of Ceropegia candelabrum with zinc nitrate using a simple hydrothermal process. The synthesized ZnO-NPs showed an absorption peak at 320 nm which is one of the characteristic features of ZnO-NPs. The FT-IR characterization revealed a spectrum band at 551.93 cm- 1 corresponding to the functional group metal oxide. SEM images showed agglomeration of nanoparticles with a hexagonal shape. XRD results are in corroboration with SEM images as the synthesized particles were of hexagonal wurtzite shape and the size of the particles was in the range of 12-35 nm calculated using Scherrer's formula. The elemental analysis using EDS confirmed high zinc content of 70.48% stating that the process of biosynthesis of nanoparticles was carried out in accordance. The biosynthesized ZnO-NPs offered significant antibacterial potential against S. aureus, B. subtilis, E. coli and S. typhi. The antioxidant results revealed significant (p ≤ 0.05) RSA from 0% to 55.43% (IC50 = 95.09 μg mL- 1). The results affirm that biosynthesized ZnO-NPs can be used as an alternative to present-day chemical compounds.

Nano characterization of gunshot residues from Brazilian ammunition.

PubMed

Melo, Lis G A; Martiny, Andrea; Pinto, André L

2014-07-01

Gunshot residues (GSR) from a total of nine different caliber ammunitions produced in Brazil were analyzed and characterized by transmission (TEM) and scanning electron microscopy (SEM). GSR particles are composed of spherical particles of several micrometers of diameter containing distinct amounts of lead, barium and antimony, along with other organic and inorganic elements arising from the primer, gunpowder, the gun and the bullet itself. This study was carried out to obtain additional information on the properties of GSR nanoparticles originated from different types of regular ammunition produced in Brazil by CBC. Besides the SEM, we have used a TEM, exploring its high magnification capability and ability to explore internal structure and chemical composition of submicron particles. We observed that CBC ammunition generated smaller particles than usually reported for other ammunitions and that the three component particles are not a majority. TEM analysis revealed that GSR are partially composed of sub-micron particles as well. The electron diffraction pattern from these particles confirmed them to be mainly composed of lead oxides crystalline nanoparticles that may be agglomerated into larger particles. Energy dispersive X-ray spectroscopy revealed that most of them were composed of two elements, especially PbSb. Ba was not a common element found in the nanoparticles. Copyright © 2014 Elsevier Ireland Ltd. All rights reserved.

Pronounced effects of the nominal concentrations of WO3 and Ag: WO3 nano-plates (obtained by a co-precipitation method) on their structural, morphological and optical properties

NASA Astrophysics Data System (ADS)

Rajendran, V.; Deepa, B.

2018-03-01

Tungsten oxide and different concentration of silver (Ag)-doped tungsten oxide nano material were synthesized by co-precipitation technique. The functional vibrations, structure, and morphology of as-prepared nano material were studied by Fourier transmission infrared spectroscopy, X-ray diffraction, scanning electron microscopy (SEM) and High-resolution transmission electron microscopy (HR-TEM) techniques. The SEM and HR-TEM analysis revealed the formation of nano-plate/nano rods with an average diameter of 40-80 nm diameter and 1-1.5 mm length. Fluorescence (PL) and UV-visible absorption techniques have been used to study the optical properties of the prepared nanoparticles. The observed red shift in the visible absorption spectra confirmed the promoted electron-phonon interaction in WO3 and Ag: WO3 nanoparticles compared to bulk structures. The photoluminescence of nanocrystalline Ag2+ doped WO3 exhibited a strong violet-blue, blue-green emission. Concentration dependence of the emission intensity of Ag2+ in WO3 was studied, and the significant concentration was found to be 0.5% of Ag: WO3. The effluent dye degradation executed for the 0.5% of Ag: WO3 sample under the visible light which reveals the highest degradation efficiency in appropriate time.

The utility of the bifactor model in understanding unique components of anxiety sensitivity in a South Korean sample.

PubMed

Ebesutani, Chad; Kim, Mirihae; Park, Hee-Hoon

2016-08-01

The present study was the first to examine the applicability of the bifactor structure underlying the Anxiety Sensitivity Index-3 (ASI-3) in an East Asian (South Korean) sample and to determine which factors in the bifactor model were significantly associated with anxiety, depression, and negative affect. Using a sample of 289 South Korean university students, we compared (a) the original 3-factor AS model, (b) a 3-group bifactor AS model, and (c) a 2-group bifactor AS model (with only the physical and social concern group factors present). Results revealed that the 2-group bifactor AS model fit the ASI-3 data the best. Relatedly, although all ASI-3 items loaded on the general AS factor, the Cognitive Concern group factor was not defined in the bifactor model and may therefore need to be omitted in order to accurately model AS when conducting factor analysis and structural equation modeling (SEM) in cross cultural contexts. SEM results also revealed that the general AS factor was the only factor from the 2-group bifactor model that significantly predicted anxiety, depression, and negative affect. Implications and importance of this new bifactor structure of Anxiety Sensitivity in East Asian samples are discussed. Copyright © 2016 Elsevier B.V. All rights reserved.

Biosynthesis of silver nanoparticles using Alternanthera sessilis (Linn.) extract and their antimicrobial, antioxidant activities.

PubMed

Niraimathi, K L; Sudha, V; Lavanya, R; Brindha, P

2013-02-01

The present work focuses the use of the aqueous extract of Alternanthera sessilis Linn. (Amaranthaceae) in producing silver nanoparticles (AgNPs) from silver nitrate aqueous. Phytochemical analysis of the extract revealed the presence of alkaloid, tannins, ascorbic acid, carbohydrates and proteins and they serve as effective reducing and capping agents for converting silver nitrate into nanoparticles. The synthesized silver nanoparticles (AgNPs) were also tested for proteins and ascorbic acid. Its pH was also determined (5.63). The AgNPs obtained was characterized by UV-vis spectroscopy, FT-IR spectroscopy, SEM, Zeta sizer and TG-DSC. SEM images which revealed the presence of various shapes and sizes. FT-IR spectrum showed the AgNPs having a coating of proteins indicating a dual role of bio-molecules responsible for capping and efficient stabilization of the silver nanoparticles. Presence of impurities and melting point profile were screened by TG-DSC analyzer. AgNPs were synthesized from the silver nitrate through the reducing power of ascorbic acid present in A. sessilis leaves. In this study, we also investigated antimicrobial and antioxidant activity of green synthesized AgNPs. The antimicrobial activity is investigated by Bauer et al.'s method. Antioxidant activity was done by DPPH method. Copyright © 2012 Elsevier B.V. All rights reserved.

The double capsules in macro-textured breast implants.

PubMed

Giot, Jean-Philippe; Paek, Laurence S; Nizard, Nathanael; El-Diwany, Mostafa; Gaboury, Louis A; Nelea, Monica; Bou-Merhi, Joseph S; Harris, Patrick G; Danino, Michel A

2015-10-01

Breast implants are amongst the most widely used types of permanent implants in modern medicine and have both aesthetic and reconstructive applications with excellent biocompatibility. The double capsule is a complication associated with textured prostheses that leads to implant displacement; however, its etiology has yet to be elucidated. In this study, 10 double capsules were sampled from breast expander implants for in-depth analysis; histologically, the inner capsular layer demonstrated highly organized collagen in sheets with delamination of fibers. At the prosthesis interface (PI) where the implant shell contacts the inner capsular layer, scanning electron microscopy (SEM) revealed a thin layer which mirrored the three-dimensional characteristics of the implant texture; the external surface of the inner capsular layer facing the intercapsular space (ICS) was flat. SEM examination of the inner capsule layer revealed both a large bacterial presence as well as biofilm deposition at the PI; a significantly lower quantity of bacteria and biofilm were found at the ICS interface. These findings suggest that the double capsule phenomenon's etiopathogenesis is of mechanical origin. Delamination of the periprosthetic capsule leads to the creation of the ICS; the maintained separation of the 2 layers subsequently alters the biostability of the macro-textured breast implant. Copyright © 2015 Elsevier Ltd. All rights reserved.

Motivational climate, goal orientation, perceived sport ability, and enjoyment within Finnish junior ice hockey players.

PubMed

Jaakkola, T; Ntoumanis, N; Liukkonen, J

2016-01-01

The aim of this study was to investigate the relations among situational motivational climate, dispositional approach and avoidance achievement goals, perceived sport ability, and enjoyment in Finnish male junior ice hockey players. The sample comprised 265 junior B-level male players with a mean age of 17.03 years (SD = 0.63). Players filled questionnaires tapping their perceptions of coach motivational climate, achievement goals, perceived sport ability, and enjoyment. For the statistical analysis, players were divided into high and low perceived sport ability groups. Multigroup structural equation modeling (SEM) revealed an indirect path from task-involving motivational climate via task-approach goal to enjoyment. Additionally, SEM demonstrated four other direct associations, which existed in both perceived ability groups: from ego-involving motivational climate to ego-approach and ego-avoidance goals; from ego-approach goal to ego-avoidance goal; and from task-avoidance goal to ego-avoidance goal. Additionally, in the high perceived sport ability group, there was an association from task-involving motivational climate to enjoyment. The results of this study reveal that motivational climate emphasizing effort, personal development and improvement, and achievement goal mastering tasks are significant elements of enjoyment in junior ice hockey. © 2015 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

Structural analysis of reactionary dentin formed in response to polymicrobial invasion

PubMed Central

Charadram, Nattida; Austin, Christine; Trimby, Patrick; Simonian, Mary; Swain, Michael V.; Hunter, Neil

2013-01-01

In response to microbial invasion of dentin odontoblasts secrete an altered calcified matrix termed reactionary dentin (Rd). 3D reconstruction of focused-ion-beam scanning electron microscopy (FIB-SEM) image slices revealed helical tubular structures in Rd that contrasted with regular cylindrical tubules characteristic of dentin from healthy teeth and affected so-called physiological dentin (Pd) lying exterior to Rd. This helical structure in Rd provided effective constriction of tubule lumen diameter that formed a barrier to bacterial advance towards the dental pulp. SEM of resin cast preparations revealed altered extension of odontoblast processes through Rd. The distribution of key mineral elements was studied by combination of 3D reconstruction of focused-ion-beam based X-ray microanalysis (FIB-EDS), laser ablation-inductively coupled plasma-mass spectrometry (LA-ICP-MS) and diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS). There was a marked redistribution of calcium and phosphorous in Rd together with an increase of diffusely deposited magnesium compatible with the mineral deposition phase of synthesis of this altered matrix. Changes in tubule structure and mineral content characteristic of Rd are consistent with reduced hardness and lower elastic modulus reported for this matrix. Findings provide insight into the unique structure of Rd synthesised as a primary response to infection. PMID:23261402

FIB/SEM and SEM/EDS microstructural analysis of metal-ceramic and zirconia-ceramic interfaces.

PubMed

Massimi, F; Merlati, G; Sebastiani, M; Battaini, P; Menghini, P; Bemporad, E

2012-01-10

Recently introduced FIB/SEM analysis in microscopy seems to provide a high-resolution characterization of the samples by 3D (FIB) cross-sectioning and (SEM) high resolution imaging. The aim of this study was to apply the FIB/SEM and SEM/EDS analysis to the interfaces of a metal-ceramic vs. two zirconia-ceramic systems. Plate samples of three different prosthetic systems were prepared in the dental lab following the manufacturers' instructions, where metal-ceramic was the result of a ceramic veneering (porcelain-fused-to-metal) and the two zirconia-ceramic systems were produced by the dedicated CAD-CAM procedures of the zirconia cores (both with final sintering) and then veneered by layered or heat pressed ceramics. In a FIB/SEM equipment (also called DualBeam), a thin layer of platinum (1 μm) was deposited on samples surface crossing the interfaces, in order to protect them during milling. Then, increasingly deeper trenches were milled by a focused ion beam, first using a relatively higher and later using a lower ion current (from 9 nA to 0.28 nA, 30KV). Finally, FEG-SEM (5KV) micrographs (1000-50,000X) were acquired. In a SEM the analysis of the morphology and internal microstructure was performed by 13KV secondary and backscattered electrons signals (in all the samples). The compositional maps were then performed by EDS probe only in the metal-ceramic system (20kV). Despite the presence of many voids in all the ceramic layers, it was possible to identify: (1) the grain structures of the metallic and zirconia substrates, (2) the thin oxide layer at the metal-ceramic interface and its interactions with the first ceramic layer (wash technique), (3) the roughness of the two different zirconia cores and their interactions with the ceramic interface, where the presence of zirconia grains in the ceramic layer was reported in two system possibly due to sandblasting before ceramic firing.

The effect of CO2 and Nd:YAP lasers on CAD/CAM Ceramics: SEM, EDS and thermal studies.

PubMed

El Gamal, Ahmed; Fornaini, Carlo; Rocca, Jean Paul; Muhammad, Omid H; Medioni, Etienne; Cucinotta, Annamaria; Brulat-Bouchard, Nathalie

2016-03-31

The objective of this study was to investigate the interaction of infrared laser light on Computer Aided Design and Computer Aided Manufacturing (CAD/CAM) ceramic surfaces. Sixty CAD/CAM ceramic discs were prepared and divided into two different groups: lithiumdisilicate ceramic (IPSe.maxCADs) and Zirconia ceramic (IPSe.maxZirCADs). The laser irradiation was performed on graphite and non-graphite surfaces with a Carbon Dioxide laser at 5W and 10W power in continuous mode (CW mode) and with Neodymium Yttrium Aluminum Perovskite (Nd:YAP) laser at 10W. Surface textures and compositions were examined using Scanning Electron Microscopy (SEM), and Energy Dispersive Spectroscopy (EDS). Thermal elevation was measured by thermocouple during laser irradiation. The SEM observation showed a rough surface plus cracks and fissures on CO2 10W samples and melting areas in Nd:YAP samples; moreover, with CO2 5W smooth and shallow surfaces were observed. EDS analysis revealed that laser irradiation does not result in modifications of the chemical composition even if minor changes in the atomic mass percentage of the components were registered. Thermocouple showed several thermal changes during laser irradiation. CO2 and Nd:YAP lasers modify CAD/CAM ceramic surface without chemical composition modifications.

Does Depressive Affect Mediate the Relationship between Self-Care Capacity and Nutritional Status Among Rural Older Adults? : A Structural Equation Modeling Approach.

PubMed

Jung, Seung Eun; Bishop, Alex J; Kim, Minjung; Hermann, Janice; Kim, Giyeon; Lawrence, Jeannine

2017-01-01

This study examined the relationships of self-care capacity and depressive affect on nutritional status and whether depressive affect mediated the relationship of self-care capacity on nutritional status. A convenience sample of 171 rural community-dwelling older adults, 65 years and above, participated. Structural equation modeling (SEM) was conducted to test a mediation model. The hypothesized SEM model was supported with adequate fit (χ 2 (1) = 1.87, p = 0.17; CFI = 0.94; RMSEA = 0.07; SRMR = 0.03). SEM analysis revealed a significant positive direct effect of self-care capacity on nutritional status (γ = 0.14, p = 0.042). Significant negative direct effects were observed for self-care capacity on depressive affect (γ = -0.15, p = 0.027) and for depressive affect on nutritional status (β = -0.27, p < 0.01). Depressive affect was also observed to partially mediate the relationship of self-care capacity on nutrition status (γ = 0.04, p = 0.046). Findings highlight the importance of emotional well-being on rural older adults' nutritional status, particularly those with decreased ability to engage in self-care practices.

Evaluation of environmental scanning electron microscopy for analysis of Proteus mirabilis crystalline biofilms in situ on urinary catheters

PubMed Central

Holling, Nina; Dedi, Cinzia; Jones, Caroline E; Hawthorne, Joseph A; Hanlon, Geoffrey W; Salvage, Jonathan P; Patel, Bhavik A; Barnes, Lara M; Jones, Brian V

2014-01-01

Proteus mirabilis is a common cause of catheter-associated urinary tract infections and frequently leads to blockage of catheters due to crystalline biofilm formation. Scanning electron microscopy (SEM) has proven to be a valuable tool in the study of these unusual biofilms, but entails laborious sample preparation that can introduce artefacts, undermining the investigation of biofilm development. In contrast, environmental scanning electron microscopy (ESEM) permits imaging of unprocessed, fully hydrated samples, which may provide much insight into the development of P. mirabilis biofilms. Here, we evaluate the utility of ESEM for the study of P. mirabilis crystalline biofilms in situ, on urinary catheters. In doing so, we compare this to commonly used conventional SEM approaches for sample preparation and imaging. Overall, ESEM provided excellent resolution of biofilms formed on urinary catheters and revealed structures not observed in standard SEM imaging or previously described in other studies of these biofilms. In addition, we show that energy-dispersive X-ray spectroscopy (EDS) may be employed in conjunction with ESEM to provide information regarding the elemental composition of crystalline structures and demonstrate the potential for ESEM in combination with EDS to constitute a useful tool in exploring the mechanisms underpinning crystalline biofilm formation. PMID:24786314

Role of different chelating agent in synthesis of copper doped tin oxide (Cu-SnO2) nanoparticles

NASA Astrophysics Data System (ADS)

Saravanakumar, B.; Anusiya, A.; Rani, B. Jansi; Ravi, G.; Yuvakkumar, R.

2018-05-01

An attempt was made to synthesis the copper doped tin oxide (Cu-SnO2) nanoparticles by adopting different chelating agents (NaOH, KOH and C2H2O4) by Sol-gel process. The synthesized products were characterized by XRD, Photoluminescence (PL), Infra- Red (FTIR) and SEM analysis. The XRD confirms the formation of Cu-SnO2 shows the maximum peak at 33.8° with lattice plane (101). The PL peak at 361 and 382 nm due to the recombination of electron in conduction band to valence band infers the optical properties. The IR spectra correspond to the peak at 551 and 620 cm-1 attributed to the characteristics peak for Cu-SnO2 nanoparticles. The SEM images for all three Cu-SnO2 nanoparticles formed by three chelating agent (NaOH, KOH and C2H2O4) facilitates the formation mechanism and the chelating agent Oxalic acid results in formation of nano flowers with diverse layers orientated in random direction. Further SEM studies reveal that, the Cu-SnO2 nanoparticles formed by oxalic acid could posses high surface area with large number layered structured enables the better electrochemical properties and its applications.

Quantitative light and scanning electron microscopy of ferret sperm.

PubMed

Van der Horst, G; Curry, P T; Kitchin, R M; Burgess, W; Thorne, E T; Kwiatkowski, D; Parker, M; Atherton, R W

1991-11-01

Sperm were obtained via electroejaculation from Domestic ferret, (Mustela putorius furo), Siberian ferret (M. eversmanni), Black-footed ferret (M. nigripes), and a hybrid between Siberian and Domestic, called the Fitch ferret (M. sp.). Comparisons of sperm were made by four different microscopy techniques to determine whether differences exist among species. First, Nomarski differential interference microscopy could be used to distinguish domestic ferret sperm from the others on the basis of the structure of the posterior part of the acrosome. Second, both silver staining, which demonstrates argentophilic protein distribution, and scanning electron microscopy (SEM), revealed differences among the morphology of sperm for each species; variation in the unique appearance of the acrosome in ferret sperm was detected especially well by SEM. To quantify differences in morphology, five sperm head parameters were measured using image analysis; light microscopy produced significantly larger values than did SEM (all parameters and all species but Fitch), and there were significant differences owing to species for all parameters but one. Generally, our data demonstrate the value of complementary techniques to distinguish among sperm of closely related species and more specifically may help establish evolutionary relationships among the ferret species studied. In addition, they provide baseline data important for the captive breeding of the endangered Black-footed ferret.

Microstructural analysis and thermoelectric properties of Sn-Al co-doped ZnO ceramics

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

Hoemke, Joshua, E-mail: jhoemke@sigma.t.u-tokyo.ac.jp; Tochigi, Eita; Shibata, Naoya

2016-08-26

Sn-Al co-doped polycrystalline ZnO ceramics were prepared by sintering in air. Phase and microstructure analysis was performed by X-ray diffraction and SEM-EDS and thermoelectric properties were measured. XRD analysis showed a ZnO primary phase as well as secondary phase peaks due to the formation of a Zn{sub 2}SnO{sub 4} spinel phase or SnO{sub 2}(ZnO:Sn-Al){sub m} intergrowth phase. SEM analysis revealed a dense microstructure with a small number of nanometric pores, consistent with the measured density of 5.48 g/cm{sup 3}. An activated electrical conductivity characteristic of a semiconducting material was observed as well as a negative Seebeck coefficient with both valuesmore » increasing in absolute value from RT to 730 °C. The power factor had a maximum value of 3.73×10{sup −4} W m{sup −1} K{sup −2} at 730 °C. Thermal conductivity measurements showed a significant reduction over the measured temperature range compared to undoped ZnO. This could be attributed to grain size reduction, the formation of a nanoscale secondary phase or a reduction in crystallinity caused by Sn-Al co-doping. A maximum ZT of 0.06 was obtained at 750 °C for the Sn-Al co-doped ZnO ceramics.« less

Using multiple group modeling to test moderators in meta-analysis.

PubMed

Schoemann, Alexander M

2016-12-01

Meta-analysis is a popular and flexible analysis that can be fit in many modeling frameworks. Two methods of fitting meta-analyses that are growing in popularity are structural equation modeling (SEM) and multilevel modeling (MLM). By using SEM or MLM to fit a meta-analysis researchers have access to powerful techniques associated with SEM and MLM. This paper details how to use one such technique, multiple group analysis, to test categorical moderators in meta-analysis. In a multiple group meta-analysis a model is fit to each level of the moderator simultaneously. By constraining parameters across groups any model parameter can be tested for equality. Using multiple groups to test for moderators is especially relevant in random-effects meta-analysis where both the mean and the between studies variance of the effect size may be compared across groups. A simulation study and the analysis of a real data set are used to illustrate multiple group modeling with both SEM and MLM. Issues related to multiple group meta-analysis and future directions for research are discussed. Copyright © 2016 John Wiley & Sons, Ltd. Copyright © 2016 John Wiley & Sons, Ltd.

A SEM-correlation of the anatomy of the vitreous body: making visible the invisible.

PubMed

Jongebloed, W L; Humalda, D; Worst, J F

1986-12-30

The naked human vitreous (sclera, iris and cornea removed) suspended in water does not reveal inner structures. After ink injection into the vitreous, the presence of different compartments and the existence of cisterns becomes evident. A concept of the internal system of cisterns is given on the basis of stereoscopic-lightmicroscopic images. An attempt is made to correlate images of the complete vitreous body, obtained with a stereo-lightmicroscope, with images of segments of cisternal walls produced with a scanning electron-microscope (SEM). A comparison is made between SEM-images of the vitreous bodies of human and rabbit eyes.

Laboratory plant study on the melting process of asbestos waste

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

Sakai, Shinichi; Terazono, Atsushi; Takatsuki, Hiroshi

The melting process was studied as a method of changing asbestos into non-hazardous waste and recovering it as a reusable resource. In an initial effort, the thermal behaviors of asbestos waste in terms of physical and chemical structure have been studied. Then, 10 kg/h-scale laboratory plant experiments were carried out. By X-ray diffraction analysis, the thermal behaviors of sprayed-on asbestos waste revealed that chrysotile asbestos waste change in crystal structure at around 800 C, and becomes melted slag, mainly composed of magnesium silicate, at around 1,500 C. Laboratory plant experiments on the melting process of sprayed-on asbestos have shown thatmore » melted slag can be obtained. X-ray diffraction analysis of the melted slag revealed crystal structure change, and SEM analysis showed the slag to have a non-fibrous form. And more, TEM analysis proved the very high treatment efficiency of the process, that is, reduction of the asbestos content to 1/10{sup 6} as a weight basis. These analytical results indicate the effectiveness of the melting process for asbestos waste treatment.« less

Why semicarbazide (SEM) is not an appropriate marker for the usage of nitrofurazone on agricultural animals.

PubMed

Stadler, Richard H; Verzegnassi, Ludovica; Seefelder, Walburga; Racault, Lucie

2015-01-01

A comprehensive global database on semicarbazide (SEM) in foodstuffs and food ingredients is presented, with over 4000 data collected in foods such as seafood (crustaceans, fish powders), meat (beef, chicken powders), dairy products (e.g. raw milk, milk powders, whey, sweet buttermilk powder, caseinate, yoghurt, cheese), honey and other ingredients. The results provide evidence that the presence of SEM in certain dairy ingredients (whey, milk protein concentrates) is a by-product of chemical reactions taking place during the manufacturing process. Of the dairy ingredients tested (c. 2000 samples), 5.3% showed traces of SEM > 0.5 µg/kg. The highest incidence of SEM-positive samples in the dairy category were whey (powders, liquid) and milk protein concentrates (35% positive), with up to 13 µg/kg measured in a whey powder. Sweet buttermilk powder and caseinate followed, with 27% and 9.3% positives, respectively. SEM was not detected in raw milk, or in yoghurt or cheese. Of the crustacean products (shrimp and prawn powders) tested, 44% were positive for SEM, the highest value measured at 284 µg/kg. Fish powders revealed an unexpectedly high incidence of positive samples (25%); in this case, fraudulent addition of shellfish shells or carry-over during processing cannot be excluded. Overall, the data provide new insights into the occurrence of SEM (for dairy products and fish powders), substantially strengthening the arguments that SEM in certain food categories is not a conclusive marker of the use of the illegal antibiotic nitrofurazone.

Characterization of dermal plates from armored catfish Pterygoplichthys pardalis reveals sandwich-like nanocomposite structure.

PubMed

Ebenstein, Donna; Calderon, Carlos; Troncoso, Omar P; Torres, Fernando G

2015-05-01

Dermal plates from armored catfish are bony structures that cover their body. In this paper we characterized structural, chemical, and nanomechanical properties of the dermal plates from the Amazonian fish Pterygoplichthys pardalis. Analysis of the morphology of the plates using scanning electron microscopy (SEM) revealed that the dermal plates have a sandwich-like structure composed of an inner porous matrix surrounded by two external dense layers. This is different from the plywood-like laminated structure of elasmoid fish scales but similar to the structure of osteoderms found in the dermal armour of some reptiles and mammals. Chemical analysis performed using Fourier transform infrared spectroscopy (FTIR), differential scanning calorimetry (DSC) and X-ray diffraction (XRD) results revealed similarities between the composition of P. pardalis plates and the elasmoid fish scales of Arapaima gigas. Reduced moduli of P. pardalis plates measured using nanoindentation were also consistent with reported values for A. gigas scales, but further revealed that the dermal plate is an anisotropic and heterogeneous material, similar to many other fish scales and osteoderms. It is postulated that the sandwich-like structure of the dermal plates provides a lightweight and tough protective layer. Copyright © 2015 Elsevier Ltd. All rights reserved.

ADHESION OF AN ENDODONTIC SEALER TO DENTIN AND GUTTA-PERCHA: SHEAR AND PUSH-OUT BOND STRENGTH MEASUREMENTS AND SEM ANALYSIS

PubMed Central

Teixeira, Cleonice Silveira; Alfredo, Edson; Thomé, Luis Henrique de Camargo; Gariba-Silva, Ricardo; Silva-Sousa, Yara T. Correa; Sousa, Manoel Damião

2009-01-01

The use of an adequate method for evaluation of the adhesion of root canal filling materials provides more reliable results to allow comparison of the materials and substantiate their clinical choice. The aims of this study were to compare the shear bond strength (SBS) test and push-out test for evaluation of the adhesion of an epoxy-based endodontic sealer (AH Plus) to dentin and guttapercha, and to assess the failure modes on the debonded surfaces by means of scanning electron microscopy (SEM). Three groups were established (n=7): in group 1, root cylinders obtained from human canines were embedded in acrylic resin and had their canals prepared and filled with sealer; in group 2, longitudinal sections of dentin cylinders were embedded in resin with the canal surface smoothed and turned upwards; in group 3, gutta-percha cylinders were embedded in resin. Polyethylene tubes filled with sealer were positioned on the polished surface of the specimens (groups 2 and 3). The push-out test (group 1) and the SBS test (groups 2 and 3) were performed in an Instron universal testing machine running at crosshead speed of 1 mm/min. Means (±SD) in MPa were: G1 (8.8±1.13), G2 (5.9±1.05) and G3 (3.8±0.55). Statistical analysis by ANOVA and Student's t-test (α=0.05) revealed statistically significant differences (p<0.01) among the groups. SEM analysis showed a predominance of adhesive and mixed failures of AH Plus sealer. The tested surface affected significantly the results with the sealer reaching higher bond strength to dentin than to guttapercha with the SBS test. The comparison of the employed methodologies showed that the SBS test produced significantly lower bond strength values than the push-out test, was skilful in determining the adhesion of AH Plus sealer to dentin and gutta-percha, and required specimens that could be easily prepared for SEM, presenting as a viable alternative for further experiments. PMID:19274399

Application of biocompatible magnetite nanoparticles for the removal of arsenic and copper from water

NASA Astrophysics Data System (ADS)

Iconaru, S. L.; Beuran, M.; Turculet, C. S.; Negoi, I.; Teleanu, G.; Prodan, A. M.; Motelica-Heino, M.; Guégan, R.; Ciobanu, C. S.; Jiga, G.; Predoi, Daniela

2018-02-01

The progress of nanotechnology made possible the use of nanomaterials as adsorbents and magnetic iron oxides represents one of the first generations of nanoscale materials used in environment technologies [1]. A systematic characterization of commercial magnetite (Fe3O4) is presented in this research. The commercial (Fe3O4) magnetic adsorbents were characterized by various characterizations methods such as X-ray diffraction (XRD), Scanning Electron Microscopy (SEM) and Energy Dispersive X-ray analysis (EDX). This study was also focused on the study of adsorption isotherms and the kinetics evaluation. X-ray studies indicated that As3+ and Cu2+ removed by Fe3O4 did not seem to alter the structure of Fe3O4 but they were highlighted in the EDX analysis. In addition, the SEM studies were consistent with the XRD results. The rate of adsorption of contaminants, in contaminated solutions decreases when the amount of contaminant increases in all experiments performed. The results revealed that Fe3O4 nanoparticles are promising candidates which could be used as sorbents for the removal of arsenic from the marine environment, for site remediation and groundwater treatment.

Zr doping dependence of structural and magnetic properties of cobalt ferrite synthesized by sol-gel based Pechini method

NASA Astrophysics Data System (ADS)

Motavallian, Pourya; Abasht, Behzad; Abdollah-Pour, Hassan

2018-04-01

Nanocrystalline CoZrxFe2-xO4 (0 ≤ x ≤ 0.3 in a step of 0.05) powders were synthesized by Pechini sol-gel method. The dry gel was grinded and calcined at 700 °C in a static air atmosphere for 1 h. Some tests such as thermo gravimetric analysis (TGA) combined with differential analysis (DTA), fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM) and vibrating sample magnetometer (VSM) were carried out to investigate the thermal behaviour, structural bonds identification, crystallographic properties, morphology and magnetic properties of the obtained powders. X-ray diffraction revealed a single-phase cubic spinel structure for all samples, where the crystallite size decreases; the lattice parameter simultaneously increases with substitution of Zr. The results of FE-SEM showed that the particle size is in the 20-70 nm range. The magnetic properties such as saturation magnetization (Ms), remanent magnetization (Mr) and coercivity (Hc) were measured from the hysteresis loops. The greatest amount of saturation magnetization for CoZr0.05Fe1.95O4 sample was 67.9 emu·g-1.

Comparative biomechanical and microstructural analysis of native versus peracetic acid-ethanol treated cancellous bone graft.

PubMed

Rauh, Juliane; Despang, Florian; Baas, Jorgen; Liebers, Cornelia; Pruss, Axel; Gelinsky, Michael; Günther, Klaus-Peter; Stiehler, Maik

2014-01-01

Bone transplantation is frequently used for the treatment of large osseous defects. The availability of autologous bone grafts as the current biological gold standard is limited and there is a risk of donor site morbidity. Allogenic bone grafts are an appealing alternative, but disinfection should be considered to reduce transmission of infection disorders. Peracetic acid-ethanol (PE) treatment has been proven reliable and effective for disinfection of human bone allografts. The purpose of this study was to evaluate the effects of PE treatment on the biomechanical properties and microstructure of cancellous bone grafts (CBG). Forty-eight human CBG cylinders were either treated by PE or frozen at -20 °C and subjected to compression testing and histological and scanning electron microscopy (SEM) analysis. The levels of compressive strength, stiffness (Young's modulus), and fracture energy were significantly decreased upon PE treatment by 54%, 59%, and 36%, respectively. Furthermore, PE-treated CBG demonstrated a 42% increase in ultimate strain. SEM revealed a modified microstructure of CBG with an exposed collagen fiber network after PE treatment. We conclude that the observed reduced compressive strength and reduced stiffness may be beneficial during tissue remodeling thereby explaining the excellent clinical performance of PE-treated CBG.

Preparation of isolated nuclei from K 562 haemopoietic cell line for high resolution scanning electron microscopy.

PubMed

Reipert, S; Reipert, B M; Allen, T D

1994-09-01

The aim of the work is to visualise nuclear pore complexes (NPCs) in mammalian cells by high resolution scanning electron microscopy. A detergent-free isolation protocol was employed to obtain clean nuclei from the haemopoietic cell line K 562. Nuclear isolation was performed by mechanical homogenisation under hypotonic conditions followed by purification of the nuclear fraction. The isolated nuclei were attached to silicon chips, fixed, critical point dried, and sputter coated with a thin film (3-4 nm) of tantalum. Analysis of the nuclear surface by scanning electron microscopy (SEM) revealed a strong sensitivity of the outer nuclear membrane (ONM) to disruption during the isolation procedure. A significant reduction of the characteristic pattern of damage to the ONM was achieved by means of an isopicnic centrifugation on an isoosmolar balanced Percoll gradient. Analysis of the population of isolated nuclei by flow cytometry showed no signs of cell cycle specific losses of nuclei during isolation. The SEM investigations of the morphology of the nuclear envelope (NE) and of substructural details of NPCs and polyribosomes were performed using an in-lens field emission scanning electron microscope.

Structural and electrical properties of CZTS thin films by electrodeposition

NASA Astrophysics Data System (ADS)

Rao, M. C.; Basha, Sk. Shahenoor

2018-06-01

CZTS (Cu2ZnSnS4) thin films were coated on ITO glass substrates by single bath electrodeposition technique. The prepared films were subsequently characterized by XRD, SEM, FTIR, UV-visible spectroscopy and Raman studies. The thickness of the thin films was measured by wedge method. X-ray diffraction studies revealed the formation of polycrystalline phase. The morphological surface of the prepared thin films was examined by SEM and AFM and showed the presence of microcrystals on the surface of the samples. The elemental analysis and their compositional ratios present in the samples were confirmed by the energy dispersive X-ray analysis. Functional groups and the position of band structure involved in the materials were confirmed by FTIR. Optical absorption studies were performed on the prepared thin films in the wavelength ranging from 300 to 1000 nm and the energy bandgap values were found to be in the range from 1.39 to 1.60 eV. Raman spectral peak which was observed at 360 cm-1 correspond to kesterite phase, was formed due to the vibration of the molecules. Electrical measurements confirmed the nature of the thin film depending on the charge concentration present in the samples.

Laser irradiation effects on the surface, structural and mechanical properties of Al-Cu alloy 2024

NASA Astrophysics Data System (ADS)

Yousaf, Daniel; Bashir, Shazia; Akram, Mahreen; kalsoom, Umm-i.-; Ali, Nisar

2014-02-01

Laser irradiation effects on surface, structural and mechanical properties of Al-Cu-Mg alloy (Al-Cu alloy 2024) have been investigated. The specimens were irradiated for various fluences ranging from 3.8 to 5.5 J/cm2 using an Excimer (KrF) laser (248 nm, 18 ns, 30 Hz) under vacuum environment. The surface and structural modifications of the irradiated targets have been investigated by scanning electron microscope (SEM) and X-ray diffractometer (XRD), respectively. SEM analysis reveals the formation of micro-sized craters along the growth of periodic surface structures (ripples) at their peripheries. The size of the craters initially increases and then decreases by increasing the laser fluence. XRD analysis shows an anomalous trend in the peak intensity and crystallite size of the specimen irradiated for various fluences. A universal tensile testing machine and Vickers microhardness tester were employed in order to investigate the mechanical properties of the irradiated targets. The changes in yield strength, ultimate tensile strength and microhardness were found to be anomalous with increasing laser fluences. The changes in the surface and structural properties of Al-Cu alloy 2024 after laser irradiation have been associated with the changes in mechanical properties.

Synthesis and dc electrical conductivity of Cr-doped CeO2 nanoparticles by solution combustion method

NASA Astrophysics Data System (ADS)

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

2018-04-01

NPs of Ce1-xCrxO2 (x=0, 0.04, 0.08, 0.12) have been synthesized by solution combustion method using glycine as fuel. The effect of chromium on structural and dc electrical conductivity of cerium oxide nanoparticles were investigated. The obtained powder is characterized by UV-visible spectrometer, X-ray diffractometer (XRD), Scanning electron microscope (SEM) and Energy dispersive X-Ray analysis (EDS). X-ray diffraction analysis carried out on calcined samples reveals that successful incorporation of Cr2+ in CeO2 lattice where as SEM studies confirms the porous morphological structure of the prepared sample. The Keithley source meter is used to measure the dc conductivity of samples in the temperature range from 303K to 623K. The conductivity was found to be increases with increase of temperature as well as the Cr concentration due to semiconducting behavior of material and change in the charge carrier concentration. The activation energy decreases with increasing chromium concentration. The present work deals with the effect of chromium additive on structural and the D.C electrical properties Ce1-xCrxO2 NPs.

A comparative study of green composites based on tapioca starch and celluloses

NASA Astrophysics Data System (ADS)

Owi, Wei Tieng; Lin, Ong Hui; Sam, Sung Ting; Mern, Chin Kwok; Villagracia, Al Rey; Santos, Gil Nonato C.; Akil, Hazizan Md

2017-07-01

The objective of this study was to compare the properties of green composites based on tapioca starch (TS) and celluloses isolated from empty fruit bunches (EFB) and commercial celluloses from cotton linter (supplied by Sigma). Empty fruit bunches (EFB) acted as the main source to obtain the cellulose by using a chemical approach whereas the commercial cellulose from Sigma was used as reference. The TS/cellulose composite films were prepared using cellulose in varying proportions as filler into TS matrix by a casting method. The amount of celluloses added into the tapioca starch were 5, 10, 15, 20 and 25 phr (as per dry mass of TS). The celluloses were characterized using Fourier transform infrared (FTTR) spectroscopy, X-ray diffraction (XRD) and scanning electron microscopy (SEM). While the green composite films were analyzed in terms of thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), SEM and tensile properties. FTTR analysis confirmed the removal of non-cellulosic materials such as hemicelluloses and lignin from raw EFB after the chemical treatment. XRD diffractograms revealed that the crystallinity of celluloses EFB increased from 43.1 % of raw EFB to 52.1 %. SEM images showed the fibrillar structure of cellulose isolated from EFB. The TGA and derivative thermogravimetric (DTG) curves of green composite films showed no significant effect on the thermal stability. Melting temperature of TS/cellulose EFB higher than neat TS while TS/cellulose Sigma lower than neat TS. The green composite films with 15 phr cellulose from EFB filler loading provided the best tensile properties in term of its strength and modulus. However, in term of elongation at break, the percentage elongation decreased with the increased of the amount of filler loading. SEM images of the films demonstrated a good interaction between cellulose filler and TS matrix especially with the addition of 15 phr of cellulose from EFB.

Agro-industrial residue from starch extraction of Pachyrhizus ahipa as filler of thermoplastic corn starch films.

PubMed

López, O V; Versino, F; Villar, M A; García, M A

2015-12-10

Biocomposites films based on thermoplastic corn starch (TPS) containing 0.5% w/w fibrous residue from Pachyrhizus ahipa starch extraction (PASR) were obtained by melt-mixing and compression molding. PASR is mainly constituted by remaining cell walls and natural fibers, revealed by Scanning Electron Microscopy (SEM). Chemical composition of the residue indicated that fiber and starch were the principal components. Biocomposites thermo-stability was determined by Thermo-Gravimetric Analysis. A continuous PASR-TPS interface was observed by SEM, as a result of a good adhesion of the fibrous residue to starch matrix. Likewise, films containing PASR presented fewer superficial cracks than TPS ones, whereas their fracture surfaces were more irregular. Besides, the presence of PASR increased starch films roughness, due to fibers agglomerates. Films reinforced with PASR showed significantly lower water vapor permeability (WVP). In addition, PARS filler increased maximum tensile strength and Young's modulus of TPS films, thus leading to more resistant starch matrixes. Copyright © 2015 Elsevier Ltd. All rights reserved.

Correlative scanning-transmission electron microscopy reveals that a chimeric flavivirus is released as individual particles in secretory vesicles.

PubMed

Burlaud-Gaillard, Julien; Sellin, Caroline; Georgeault, Sonia; Uzbekov, Rustem; Lebos, Claude; Guillaume, Jean-Marc; Roingeard, Philippe

2014-01-01

The intracellular morphogenesis of flaviviruses has been well described, but flavivirus release from the host cell remains poorly documented. We took advantage of the optimized production of an attenuated chimeric yellow fever/dengue virus for vaccine purposes to study this phenomenon by microscopic approaches. Scanning electron microscopy (SEM) showed the release of numerous viral particles at the cell surface through a short-lived process. For transmission electron microscopy (TEM) studies of the intracellular ultrastructure of the small number of cells releasing viral particles at a given time, we developed a new correlative microscopy method: CSEMTEM (for correlative scanning electron microscopy - transmission electron microscopy). CSEMTEM analysis suggested that chimeric flavivirus particles were released as individual particles, in small exocytosis vesicles, via a regulated secretory pathway. Our morphological findings provide new insight into interactions between flaviviruses and cells and demonstrate that CSEMTEM is a useful new method, complementary to SEM observations of biological events by intracellular TEM investigations.

Extraction and characterization of gelatin biopolymer from black tilapia (Oreochromis mossambicus) scales

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

Sockalingam, K., E-mail: gd130106@siswa.uthm.edu.my; Abdullah, H. Z., E-mail: hasan@uthm.edu.my

2015-07-22

Black tilapia (Oreochromis mossambicus) fish wastes (scales) were evaluated for its suitability as sources of gelatin. Scales were subjected to acid treatment for demineralization before it undergoes thermal extraction process. The raw scales were characterized via Scanning Electron Microscopy (SEM), which demarcated the cycloid pattern of the scales. SEM images also reveal the presence of collagen fiber in the fish scale. The black tilapia fish scales yields 11.88 % of gelatin, indicating the possibility of this fish species as sources of gelatin. Further characterizations were done on both raw scale and extracted gelatin through Fourier Transform Infrared Spectroscopy (FTIR) andmore » proximate analysis. The scale gelatin shows high protein content (86.9 %) with low moisture (8.2 %) and ash (1.4 %). This further proves the effectiveness of the demineralization and extraction method used. The black tilapia fish scale is found to be a prospective source of gelatin with good chemical and functional properties.« less

Structural, morphological and optical studies of ripple-structured ZnO thin films

NASA Astrophysics Data System (ADS)

Navin, Kumar; Kurchania, Rajnish

2015-11-01

Ripple-structured ZnO thin films were prepared on Si (100) substrate by sol-gel spin-coating method with different heating rates during preheating process and finally sintered at 500 °C for 2 h in ambient condition. The structural, morphological and photoluminescence (PL) properties of the nanostructured films were analyzed by X-ray diffraction (XRD), atomic force microscopy (AFM), scanning electron microscopy (SEM) and PL spectroscopy. XRD analysis revealed that films have hexagonal wurtzite structure and texture coefficient increases along (002) plane with preheating rate. The faster heating rate produced higher crystallization and larger average crystallite size. The AFM and SEM images indicate that all the films have uniformly distributed ripple structure with skeletal branches. The number of ripples increases, while the rms roughness, amplitude and correlation length of the ripple structure decrease with preheating rates. The PL spectra show the presence of different defects in the structure. The ultraviolet emission improved with the heating rate which indicates its better crystallinity.

Improved magnetic and electrical properties of Cu doped Fe-Ni invar alloys synthesized by chemical reduction technique

NASA Astrophysics Data System (ADS)

Ahmad, Sajjad; Ziya, Amer Bashir; Ashiq, Muhammad Naeem; Ibrahim, Ather; Atiq, Shabbar; Ahmad, Naseeb; Shakeel, Muhammad; Khan, Muhammad Azhar

2016-12-01

Fe-Ni-Cu invar alloys of various compositions (Fe65Ni35-xCux, x=0, 0.2, 0.6, 1, 1.4 and 1.8) were synthesized via chemical reduction route. These alloys were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM) and vibrating sample magnetometry (VSM) techniques. The XRD analysis revealed the formation of face centered cubic (fcc) structure. The lattice parameter and the crystallite size of the investigated alloys were calculated and the line broadening indicated the nano-crystallites size of alloy powder. The particle size was estimated from SEM and it decreases by the incorporation of Cu and found to be in the range of 24-40 nm. The addition of Cu in these alloys appreciably enhances the saturation magnetization and it increases from 99 to 123 emu/g. Electrical conductivity has been improved with Cu addition. The thermal conductivity was calculated using the Wiedemann-Franz law.

Improved flotation performance of hematite fines using citric acid as a dispersant

NASA Astrophysics Data System (ADS)

Luo, Xi-mei; Yin, Wan-zhong; Sun, Chuan-yao; Wang, Nai-ling; Ma, Ying-qiang; Wang, Yun-fan

2016-10-01

In this study, citric acid was used as a dispersant to improve the flotation performance of hematite fines. The effect and mechanism of citric acid on the reverse flotation of hematite fines were investigated by flotation tests, sedimentation experiments, scanning electron microscopy (SEM), zeta-potential measurements, and X-ray photoelectron spectroscopy (XPS). The results of SEM analysis and flotation tests reveal that a strong heterocoagulation in the form of slime coating or coagulation in hematite fine slurry affects the beneficiation of hematite ores by froth flotation. The addition of a small amount of citric acid (less than 300 g/t) favorably affects the reverse flotation of hematite fines by improving particle dispersion. The results of sedimentation experiments, zeta-potential measurements, and XPS measurements demonstrate that citric acid adsorbs onto hematite and quartz surfaces via hydrogen bonding, thereby reducing the zeta potentials of mineral surfaces, strengthening the electrical double-layer repulsion between mineral particles, and dispersing the pulp particles.

Synergistic effect between ammonium polyphosphate and expandable graphite on flame-retarded poly(butylene terephthalate)

NASA Astrophysics Data System (ADS)

Zhang, Weizhou; Ren, Jiawei; Wei, Ting; Guo, Weihong

2018-02-01

In this paper, the synergistic effect of ammonium polyphosphate (APP) and expandable graphite (EG) on flame-retarded poly(butylene terephthalate) (PBT) was systermically investigated using limiting oxygen index (LOI), UL-94 testing, microscale combustion calorimetry (MCC), thermal-gravimetric analysis (TGA) and scanning electronic microscopy (SEM). PBT composites containing 20 wt% of APP: EG (1:3) combinations exhibits a high LOI value of 29.8 and reaches V-0 rating in UL-94 testing, indicating that the flame retardant property is greatly enhanced compared to the composites solely with APP or EG. SEM images show that the combination of APP and EG could promote the formation of a compact char layer. The compact char layer protects the PBT resin efficiently by preventing penetration of heat flux inside the matrix and retards the decomposition of PBT, consequently improves the thermal stability of PBT materials as revealed by TGA. All of the results demonstrate that APP and EG are high efficiency synergists for improving the flame retardation of PBT materials.

Optimization of polysaccharides extraction from watermelon rinds: Structure, functional and biological activities.

PubMed

Romdhane, Molka Ben; Haddar, Anissa; Ghazala, Imen; Jeddou, Khawla Ben; Helbert, Claire Boisset; Ellouz-Chaabouni, Semia

2017-02-01

In the present work, optimization of hot water extraction, structural characteristics, functional properties, and biological activities of polysaccharides extracted from watermelon rinds (WMRP) were investigated. The physicochemical characteristics and the monosaccharide composition of these polysaccharides were then determined using chemical composition analysis, Fourier transform infrared (FT-IR) spectroscopy, scanning electron microscopy (SEM) and gas chromatography-flame ionization detection (GC-FID). SEM images showed that extracted polysaccharides had a rough surface with many cavities. GC-FID results proved that galactose was the dominant sugar in the extracted polysaccharides, followed by arabinose, glucose, galacturonic acid, rhamnose, mannose, xylose and traces of glucuronic acid. The findings revealed that WMRP displayed excellent antihypertensive and antioxidant activities. Those polysaccharides had also a protection effect against hydroxyl radical-induced DNA damage. Functional properties of extracted polysaccharides were also evaluated. WMRP showed good interfacial dose-dependent proprieties. Overall, the results suggested that WMRP presents a promising natural source of antioxidants and antihypertensive agents. Copyright © 2016 Elsevier Ltd. All rights reserved.

Microstructure, crystallography and diagenetic alteration in fossil ostrich eggshells from Upper Palaeolithic sites of Indian peninsular region.

PubMed

Jain, Sonal; Bajpai, Sunil; Kumar, Giriraj; Pruthi, Vikas

2016-05-01

Biominerals studies are of importance as they provide an understanding of natural evolutionary processes. In this study we have investigated the fossil ostrich eggshells using Scanning Electron Microscopy (SEM), X-ray Diffraction (XRD) and Electron Backscatter Diffraction (EBSD). SEM studies demonstrated the ultrastructure of fossil eggshells and formation of calcified cuticular layer. The presence of calcified cuticle layer in eggshell is the basis for ancient DNA studies as it contains preserved biomolecules. EBSD accentuates the crystallographic structure of the ostrich eggshells with sub-micrometer resolution. It is a non-destructive tool for evaluating the extent of diagenesis in a biomineral. EBSD analysis revealed the presence of dolomite in the eggshells. This research resulted in the complete recognition of the structure of ostrich eggshells as well as the nature and extent of diagenesis in these eggshells which is vital for genetic and paleoenvironmental studies. Copyright © 2016 Elsevier Ltd. All rights reserved.

Alginate-hydroxypropylcellulose hydrogel microbeads for alkaline phosphatase encapsulation.

PubMed

Karewicz, A; Zasada, K; Bielska, D; Douglas, T E L; Jansen, J A; Leeuwenburgh, S C G; Nowakowska, M

2014-01-01

There is a growing interest in using proteins as therapeutics agents. Unfortunately, they suffer from limited stability and bioavailability. We aimed to develop a new delivery system for proteins. ALP, a model protein, was successfully encapsulated in the physically cross-linked sodium alginate/hydroxypropylcellulose (ALG-HPC) hydrogel microparticles. The obtained objects had regular, spherical shape and a diameter of ∼4 µm, as confirmed by optical microscopy and SEM analysis. The properties of the obtained microbeads could be controlled by temperature and additional coating or crosslinking procedures. The slow, sustained release of ALP in its active form with no initial burst effect was observed for chitosan-coated microspheres at pH = 7.4 and 37 °C. Activity of ALP released from ALG/HPC microspheres was confirmed by the occurance of effectively induced mineralization. SEM and AFM images revealed formation of the interpenetrated three-dimensional network of mineral, originating from the microbeads' surfaces. FTIR and XRD analyses confirmed formation of hydroxyapatite.

Correlative Scanning-Transmission Electron Microscopy Reveals that a Chimeric Flavivirus Is Released as Individual Particles in Secretory Vesicles

PubMed Central

Burlaud-Gaillard, Julien; Sellin, Caroline; Georgeault, Sonia; Uzbekov, Rustem; Lebos, Claude; Guillaume, Jean-Marc; Roingeard, Philippe

2014-01-01

The intracellular morphogenesis of flaviviruses has been well described, but flavivirus release from the host cell remains poorly documented. We took advantage of the optimized production of an attenuated chimeric yellow fever/dengue virus for vaccine purposes to study this phenomenon by microscopic approaches. Scanning electron microscopy (SEM) showed the release of numerous viral particles at the cell surface through a short-lived process. For transmission electron microscopy (TEM) studies of the intracellular ultrastructure of the small number of cells releasing viral particles at a given time, we developed a new correlative microscopy method: CSEMTEM (for correlative scanning electron microscopy - transmission electron microscopy). CSEMTEM analysis suggested that chimeric flavivirus particles were released as individual particles, in small exocytosis vesicles, via a regulated secretory pathway. Our morphological findings provide new insight into interactions between flaviviruses and cells and demonstrate that CSEMTEM is a useful new method, complementary to SEM observations of biological events by intracellular TEM investigations. PMID:24681578

Spectroscopic studies on sidewall carboxylic acid functionalization of multi-walled carbon nanotubes with valine

NASA Astrophysics Data System (ADS)

Deborah, M.; Jawahar, A.; Mathavan, T.; Dhas, M. Kumara; Benial, A. Milton Franklin

2015-03-01

The valine functionalized multi-walled carbon nanotubes (MWCNTS) were prepared and characterized by using XRD, UV-Vis, FT-IR, EPR, SEM, and EDX, spectroscopic techniques. The enhanced XRD peak (0 0 2) intensity was observed for valine functionalized MWCNTs compared with oxidized MWCNTs, which is likely due to sample purification by acid washing. UV-Vis study shows the formation of valine functionalized MWCNTs. FT-IR study confirms the presence of functional groups of oxidized MWCNTs and valine functionalized MWCNTs. The ESR line shape analysis indicates that the observed EPR line shape is a Gaussian line shape. The g-values indicate that the systems are isotropic in nature. The morphology study was carried out for oxidized MWCNTs and valine functionalized MWCNTs by using SEM. The EDX spectra revealed that the high purity of oxidized MWCNTs and valine functionalized MWCNTs. The functionalization has been chosen because, functionalization of CNTs with amino acids makes them soluble and biocompatible. Thus, they have potential applications in the field of biosensors and targeted drug delivery.

Synthesis and Characterization of Hydroxyapatite Powder by Wet Precipitation Method

NASA Astrophysics Data System (ADS)

Cahyaningrum, S. E.; Herdyastuty, N.; Devina, B.; Supangat, D.

2018-01-01

Hydroxyapatite is main inorganic component of the bone with formula Ca10(PO4)6(OH)2. Hydroxyapatite can be used as substituted bone biomaterial because biocompatible, non toxic, and osteoconductive. In this study, hydroxyapatite is synthesized using wet precipitation method from egg shell. The product was sintered at different temperatures of 800°C to 1000°C to improve its crystallinity. The hydroxyapatite was characterized by X-ray analysis, Scanning Electron Microscopy (SEM) and Fourier Transform Infrared Spectroscopy (FTIR) to reveal its phase content, morphology and types of bond present within it. The analytical results showed hydroxyapatite had range in crystallinity from 85.527 to 98.753%. The analytical functional groups showed that presence of functional groups such as OH, (PO4)3 2-, and CO3 2- that indicated as hydroxyapatite. The result of characterization SEM indicated that hydroxyapatite without sintering and HAp sintering at 800 °C were irregular shape without pore. The best hydroxyapatite with temperature sintering at 900 °C showed oval shaped with pores without agglomerated.

Physicochemical characterization of chitosan/nylon6/polyurethane foam chemically cross-linked ternary blends.

PubMed

Jayakumar, S; Sudha, P N

2013-03-15

Chitosan/nylon6/polyurethane foam (CS/Ny6/PUF) ternary blend was prepared and chemically cross-linked with glutaraldehyde. Structural, thermal and morphological studies were performed for the prepared ternary blends. Characterizations of the ternary blends were investigated by Fourier transform infrared spectroscopy (FTIR), thermo gravimetric analysis (TGA), differential scanning calorimetry (DSC), X-ray diffraction (XRD) and scanning electron microscope (SEM). The FTIR results showed that the strong intermolecular hydrogen bonds took place between CS, Ny6 and PUF. TGA and DSC studies reveal that the thermal stability of the blend is enhanced by glutaraldehyde as crosslinking agent. Results of XRD indicated that the relative crystalline of pure CS film was reduced when the polymeric network was reticulated by glutaraldehyde. Finally, the results of scanning electron microscopy (SEM) indicated that the morphology of the blend is rough and heterogeneous, further it confirms the interaction between the functional groups of the blend components. Copyright © 2012 Elsevier B.V. All rights reserved.

Electron-beam-induced post-grafting polymerization of acrylic acid onto the surface of Kevlar fibers

NASA Astrophysics Data System (ADS)

Xu, Lu; Hu, Jiangtao; Ma, Hongjuan; Wu, Guozhong

2018-04-01

The surface of Kevlar fibers was successfully modified by electron beam (EB)-induced post-grafting of acrylic acid (AA). The generation of radicals in the fibers was confirmed by electron spin resonance (ESR) measurements, and the concentration of radicals was shown to increase as the absorbed dose increased, but decrease with increasing temperature. The influence of the synthesis conditions on the degree of grafting was also investigated. The surface microstructure and chemical composition of the modified Kevlar fibers were characterized by scanning electron microscopy (SEM) and X-ray photoelectron spectroscopy (XPS). The SEM images revealed that the surface of the grafted fibers was rougher than those of the pristine and irradiated fibers. XPS analysis confirmed an increase in C(O)OH groups on the surface of the Kevlar fibers, suggesting successful grafting of AA. These results indicate that EB-induced post-grafting polymerization is effective for modifying the surface properties of Kevlar fibers.

Attempt of correlative observation of morphological synaptic connectivity by combining confocal laser-scanning microscope and FIB-SEM for immunohistochemical staining technique.

PubMed

Sonomura, Takahiro; Furuta, Takahiro; Nakatani, Ikuko; Yamamoto, Yo; Honma, Satoru; Kaneko, Takeshi

2014-11-01

Ten years have passed since a serial block-face scanning electron microscopy (SBF-SEM) method was developed [1]. In this innovative method, samples were automatically sectioned with an ultramicrotome placed inside a scanning electron microscope column, and the block surfaces were imaged one after another by SEM to capture back-scattered electrons. The contrast-inverted images obtained by the SBF-SEM were very similar to those acquired using conventional TEM. SFB-SEM has made easy to acquire image stacks of the transmission electron microscopy (TEM) in the mesoscale, which is taken with the confocal laser-scanning microcopy(CF-LSM).Furthermore, serial-section SEM has been combined with the focused ion beam (FIB) milling method [2]. FIB-incorporated SEM (FIB-SEM) has enabled the acquisition of three-dimensional images with a higher z-axis resolution com- pared to ultramicrotome-equipped SEM.We tried immunocytochemistry for FIB-SEM and correlated this immunoreactivity with that in CF-LSM. Dendrites of neurons in the rat neostriatum were visualized using a recombinant viral vector. Moreover, the thalamostriatal afferent terminals were immunolabeled with Cy5 fluorescence for vesicular glutamate transporter 2 (VGluT2). After detection of the sites of terminals apposed to the dendrites by using CF-LSM, GFP and VGluT2 immunoreactivities were further developed for EM by using immunogold/silver enhancement and immunoperoxidase/diaminobenzidine (DAB) methods, respectively.We showed that conventional immuno-cytochemical staining for TEM was applicable to FIB-SEM. Furthermore, several synaptic contacts, which were thought to exist on the basis of CF-LSM findings, were confirmed with FIB-SEM, revealing the usefulness of the combined method of CF-LSM and FIB-SEM. © 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.

Performance of SEM scintillation detector evaluated by modulation transfer function and detective quantum efficiency function.

PubMed

Bok, Jan; Schauer, Petr

2014-01-01

In the paper, the SEM detector is evaluated by the modulation transfer function (MTF) which expresses the detector's influence on the SEM image contrast. This is a novel approach, since the MTF was used previously to describe only the area imaging detectors, or whole imaging systems. The measurement technique and calculation of the MTF for the SEM detector are presented. In addition, the measurement and calculation of the detective quantum efficiency (DQE) as a function of the spatial frequency for the SEM detector are described. In this technique, the time modulated e-beam is used in order to create well-defined input signal for the detector. The MTF and DQE measurements are demonstrated on the Everhart-Thornley scintillation detector. This detector was alternated using the YAG:Ce, YAP:Ce, and CRY18 single-crystal scintillators. The presented MTF and DQE characteristics show good imaging properties of the detectors with the YAP:Ce or CRY18 scintillator, especially for a specific type of the e-beam scan. The results demonstrate the great benefit of the description of SEM detectors using the MTF and DQE. In addition, point-by-point and continual-sweep e-beam scans in SEM were discussed and their influence on the image quality was revealed using the MTF. © 2013 Wiley Periodicals, Inc.

Mitigating effects of L-selenomethionine on low-dose iron ion radiation-induced changes in gene expression associated with cellular stress.

PubMed

Nuth, Manunya; Kennedy, Ann R

2013-07-01

Ionizing radiation associated with highly energetic and charged heavy (HZE) particles poses a danger to astronauts during space travel. The aim of the present study was to evaluate the patterns of gene expression associated with cellular exposure to low-dose iron ion irradiation, in the presence and absence of L-selenomethionine (SeM). Human thyroid epithelial cells (HTori-3) were exposed to low-dose iron ion (1 GeV/n) irradiation at 10 or 20 cGy with or without SeM pretreatment. The cells were harvested 6 and 16 h post-irradiation and analyzed by the Affymetrix U133Av2 gene chip arrays. Genes exhibiting a 1.5-fold expression cut-off and 5% false discovery rate (FDR) were considered statistically significant and subsequently analyzed using the Database for Annotation, Visualization and Integrated Discovery (DAVID) for pathway analysis. Representative genes were further validated by real-time RT-PCR. Even at low doses of radiation from iron ions, global genome profiling of the irradiated cells revealed the upregulation of genes associated with the activation of stress-related signaling pathways (ubiquitin-mediated proteolysis, p53 signaling, cell cycle and apoptosis), which occurred in a dose-dependent manner. A 24-h pretreatment with SeM was shown to reduce the radiation effects by mitigating stress-related signaling pathways and downregulating certain genes associated with cell adhesion. The mechanism by which SeM prevents radiation-induced transformation in vitro may involve the suppression of the expression of genes associated with stress-related signaling and certain cell adhesion events.

[Imprints of coronary plaque particles in the PTCA balloon surface during the dilatation processing].

PubMed

Werner, D; Behrend, D; Schmitz, K P; Urbaszek, W

1995-05-01

Seventy-six PTCA-balloons after coronary angioplasty were studied for superficial changes using scanning electron microscopy (SEM) after fixing in glutardialdehyde. Coronary plaque particles were identified on the balloon surface in 52 cases (68%). Twelve new and unused balloons were subjected to the same chemical treatment and SEM showed no imprints. The average length of the longest imprinted plaques was 128 +/- 201 microns and the average number of plaque particles per balloon was 4.9 +/- 2.7. The maximal dilatation pressure and the number of dilatations showed no influence on the impregnation of plaque particles. However, longer plaque imprints tended to occur under low dilatation pressure. Imprints of plaque particles were significantly higher in patients with low cholesterol (p = 0.0001) and low triglycerides (p = 0.0016). No correlation was seen between imprint length and lipid levels. Similarly, the different balloon materials (polyethylene, polyolefincopolymer) showed no significant differences with regard to plaque occurrence. The PTCA-balloons, plaque particles and six coronary plaques obtained after endatherectomy were subjected to energy dispersive x-ray analysis (EDX) under SEM as EDX reveals qualitative and quantitative information about the structural elements. Highly significant differences in calcium, sodium, phosphorus and silicon contents (p = 0.0000) between plaque particles and balloon surface were observed, owing to the absence of these in balloon material. Thus EDX offers additional advantages over SEM in that it clearly differentiates deformed balloon surface, plaque particle, and retained contrast medium. Plaque particles can be recovered from balloon surfaces after PTCA. Depending upon their size, they could lead to coronary spasm or microembolic phenomenon.

Snow crystal imaging using scanning electron microscopy: III. Glacier ice, snow and biota

USGS Publications Warehouse

Rango, A.; Wergin, W.P.; Erbe, E.F.; Josberger, E.G.

2000-01-01

Low-temperature scanning electron microscopy (SEM) was used to observe metamorphosed snow, glacial firn, and glacial ice obtained from South Cascade Glacier in Washington State, USA. Biotic samples consisting of algae (Chlamydomonas nivalis) and ice worms (a species of oligochaetes) were also collected and imaged. In the field, the snow and biological samples were mounted on copper plates, cooled in liquid nitrogen, and stored in dry shipping containers which maintain a temperature of -196??C. The firn and glacier ice samples were obtained by extracting horizontal ice cores, 8 mm in diameter, at different levels from larger standard glaciological (vertical) ice cores 7.5 cm in diameter. These samples were cooled in liquid nitrogen and placed in cryotubes, were stored in the same dry shipping container, and sent to the SEM facility. In the laboratory, the samples were sputter coated with platinum and imaged by a low-temperature SEM. To image the firn and glacier ice samples, the cores were fractured in liquid nitrogen, attached to a specimen holder, and then imaged. While light microscope images of snow and ice are difficult to interpret because of internal reflection and refraction, the SEM images provide a clear and unique view of the surface of the samples because they are generated from electrons emitted or reflected only from the surface of the sample. In addition, the SEM has a great depth of field with a wide range of magnifying capabilities. The resulting images clearly show the individual grains of the seasonal snowpack and the bonding between the snow grains. Images of firn show individual ice crystals, the bonding between the crystals, and connected air spaces. Images of glacier ice show a crystal structure on a scale of 1-2 mm which is considerably smaller than the expected crystal size. Microscopic air bubbles, less than 15 ??m in diameter, clearly marked the boundaries between these crystal-like features. The life forms associated with the glacier were easily imaged and studied. The low-temperature SEM sample collecting and handling methods proved to be operable in the field; the SEM analysis is applicable to glaciological studies and reveals details unattainable by conventional light microscopic methods.Low temperature scanning electron microscopy (SEM) was used to observe metamorphosed snow, glacial firn, and glacial ice obtained from South Cascade Glacier in Washington State, USA. Biotic samples consisting of algae and ice worms were also collected and imaged. The SEM images provide a clear and unique view of the surface of the samples because they are generated from electrons emitted or reflected only from the surface of the sample. The SEM has a great depth of field with a wide range of magnifying capabilities.

Characterization of As-polluted soils by laboratory X-ray-based techniques coupled with sequential extractions and electron microscopy: the case of Crocette gold mine in the Monte Rosa mining district (Italy).

PubMed

Allegretta, Ignazio; Porfido, Carlo; Martin, Maria; Barberis, Elisabetta; Terzano, Roberto; Spagnuolo, Matteo

2018-06-24

Arsenic concentration and distribution were studied by combining laboratory X-ray-based techniques (wavelength dispersive X-ray fluorescence (WDXRF), micro X-ray fluorescence (μXRF), and X-ray powder diffraction (XRPD)), field emission scanning electron microscopy equipped with microanalysis (FE-SEM-EDX), and sequential extraction procedure (SEP) coupled to total reflection X-ray fluorescence (TXRF) analysis. This approach was applied to three contaminated soils and one mine tailing collected near the gold extraction plant at the Crocette gold mine (Macugnaga, VB) in the Monte Rosa mining district (Piedmont, Italy). Arsenic (As) concentration, measured with WDXRF, ranged from 145 to 40,200 mg/kg. XRPD analysis evidenced the presence of jarosite and the absence of any As-bearing mineral, suggesting a high weathering grade and strong oxidative conditions. However, small domains of Fe arsenate were identified by combining μXRF with FE-SEM-EDX. SEP results revealed that As was mainly associated to amorphous Fe oxides/hydroxides or hydroxysulfates (50-80%) and the combination of XRPD and FE-SEM-EDX suggested that this phase could be attributed to schwertmannite. On the basis of the reported results, As is scarcely mobile, even if a consistent As fraction (1-3 g As/kg of soil) is still potentially mobilizable. In general, the proposed combination of laboratory X-ray techniques could be successfully employed to unravel environmental issues related to metal(loid) pollution in soil and sediments.

Endoscopic ultrasound staging is adversely affected by placement of a self-expandable metal stent: fact or fiction?

PubMed

Shami, Vanessa M; Mahajan, Anshu; Sundaram, Vinay; Davis, Eric M; Loch, Michelle M; Kahaleh, Michel

2008-11-01

Accurate preoperative staging of pancreatic cancer (Pca) is crucial to direct management. There is a perception that endoscopic ultrasound (EUS) staging should be performed before biliary decompression because of artifact caused by self-expandable metal stents (SEMS). Our aim is to determine whether placement of SEMS affects the staging of Pca. Fifty-five patients (35 men; mean age, 67 years) with newly diagnosed Pca staged in the last 5 years and captured prospectively were divided into 2 groups matched by age, sex, and final staging. The staging accuracy of EUS in patients who had a SEMS (n = 28) was compared with patients without a SEMS (n = 27). The gold standard was surgical pathology, or cytologic confirmation of metastatic disease. Multivariate analysis was effected on age, sex, presence of SEMS, and presence of metastasis to assess prediction of staging inaccuracy. Endoscopic ultrasound correctly staged 14 (52%) of 27 patients in the no-SEMS group and 13 (46%) of 28 in the SEMS group. Logistic regression analysis identified only metastasis as a predictor of inaccuracy in EUS staging. Endoscopic ultrasound staging of Pca does not seem to be affected by the presence of a SEMS. The major reason for misstaging in both groups was failure to detect metastatic disease.

Characteristics of different frequency ranges in scanning electron microscope images

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

Sim, K. S., E-mail: kssim@mmu.edu.my; Nia, M. E.; Tan, T. L.

2015-07-22

We demonstrate a new approach to characterize the frequency range in general scanning electron microscope (SEM) images. First, pure frequency images are generated from low frequency to high frequency, and then, the magnification of each type of frequency image is implemented. By comparing the edge percentage of the SEM image to the self-generated frequency images, we can define the frequency ranges of the SEM images. Characterization of frequency ranges of SEM images benefits further processing and analysis of those SEM images, such as in noise filtering and contrast enhancement.

Computer image analysis of etched tracks from ionizing radiation

NASA Technical Reports Server (NTRS)

Blanford, George E.

1994-01-01

I proposed to continue a cooperative research project with Dr. David S. McKay concerning image analysis of tracks. Last summer we showed that we could measure track densities using the Oxford Instruments eXL computer and software that is attached to an ISI scanning electron microscope (SEM) located in building 31 at JSC. To reduce the dependence on JSC equipment, we proposed to transfer the SEM images to UHCL for analysis. Last summer we developed techniques to use digitized scanning electron micrographs and computer image analysis programs to measure track densities in lunar soil grains. Tracks were formed by highly ionizing solar energetic particles and cosmic rays during near surface exposure on the Moon. The track densities are related to the exposure conditions (depth and time). Distributions of the number of grains as a function of their track densities can reveal the modality of soil maturation. As part of a consortium effort to better understand the maturation of lunar soil and its relation to its infrared reflectance properties, we worked on lunar samples 67701,205 and 61221,134. These samples were etched for a shorter time (6 hours) than last summer's sample and this difference has presented problems for establishing the correct analysis conditions. We used computer counting and measurement of area to obtain preliminary track densities and a track density distribution that we could interpret for sample 67701,205. This sample is a submature soil consisting of approximately 85 percent mature soil mixed with approximately 15 percent immature, but not pristine, soil.

Quantifying Morphological Features of α-U3O8 with Image Analysis for Nuclear Forensics.

PubMed

Olsen, Adam M; Richards, Bryony; Schwerdt, Ian; Heffernan, Sean; Lusk, Robert; Smith, Braxton; Jurrus, Elizabeth; Ruggiero, Christy; McDonald, Luther W

2017-03-07

Morphological changes in U 3 O 8 based on calcination temperature have been quantified enabling a morphological feature to serve as a signature of processing history in nuclear forensics. Five separate calcination temperatures were used to synthesize α-U 3 O 8 , and each sample was characterized using powder X-ray diffraction (p-XRD) and scanning electron microscopy (SEM). The p-XRD spectra were used to evaluate the purity of the synthesized U-oxide; the morphological analysis for materials (MAMA) software was utilized to quantitatively characterize the particle shape and size as indicated by the SEM images. Analysis comparing the particle attributes, such as particle area at each of the temperatures, was completed using the Kolmogorov-Smirnov two sample test (K-S test). These results illustrate a distinct statistical difference between each calcination temperature. To provide a framework for forensic analysis of an unknown sample, the sample distributions at each temperature were compared to randomly selected distributions (100, 250, 500, and 750 particles) from each synthesized temperature to determine if they were statistically different. It was found that 750 particles were required to differentiate between all of the synthesized temperatures with a confidence interval of 99.0%. Results from this study provide the first quantitative morphological study of U-oxides, and reveals the potential strength of morphological particle analysis in nuclear forensics by providing a framework for a more rapid characterization of interdicted uranium oxide samples.

Bonding of contemporary glass ionomer cements to dentin.

PubMed

Yip, H K; Tay, F R; Ngo, H C; Smales, R J; Pashley, D H

2001-09-01

The objective of this study was to investigate the microtensile bond strength (microTBS) of contemporary glass ionomer cements (GIC) to sound coronal dentin. Three specimen teeth were prepared for each material tested: Fuji IX GP (GC), ChemFlex (Dentsply) and Ketac-Molar Aplicap (ESPE). GIC buildups were made according to the manufacturers' instructions. After being stored at 37 degrees C, 100% humidity for 24h, the teeth were vertically sectioned into 1x1mm beams for microTBS evaluation. Representative fractured beams were prepared for scanning (SEM) and transmission electron microscopic (TEM) examination. Results of the microTBS test were: Fuji IX GP (12.4+/-8.6MPa), ChemFlex (15.0+/-9.3MPa) and Ketac-Molar Aplicap (11.4+/-7.7MPa). One-way ANOVA and a multiple comparison test showed that ChemFlex had a statistically higher microTBS (p<0.05). SEM fractographic analysis showed that the predominant failure modes were interfacial and mixed failures. The GIC side of the fractured beams revealed dehydration cracks, a high level of porosity, and voids with an eggshell-like crust. TEM analysis of the demineralized dentin sides of the fractured beams revealed the presence of an intermediate layer along the GIC-dentin interface. This zone was present on the fractured dentin surface in the case of interfacial failure, and beneath GIC remnants in specimens that exhibited a mixed failure mode. The findings suggest that the bonding of GIC to dentin is not weak and that the microTBS values probably represent the weak yield strengths of GICs under tension.

Optimization, characterization, and efficacy evaluation of 2% chitosan scaffold for tissue engineering and wound healing

PubMed Central

Chhabra, Priyanka; Tyagi, Priyanka; Bhatnagar, Aseem; Mittal, Gaurav; Kumar, Amit

2016-01-01

Objective: To develop a chitosan-based scaffold and carry out a complete comprehensive study encompassing optimization of exact chitosan strength, product characterization, toxicity evaluation, in vitro validation in cell culture experiments, and finally in vivo efficacy in animal excision wound model. Materials and Methods: Developed chitosan scaffolds (CSs) were optimized for tissue engineering and wound healing efficacy by means of microstructure, toxicity, and biocompatibility evaluation. Results: Scanning electron microscope (SEM) studies revealed that porosity of CS decreased with increase in chitosan concentration. Chemical stability and integrity of scaffolds were confirmed by Fourier transform infrared studies. Highest swelling percentage (SP) of 500% was observed in 2%, while lowest (200%) was observed in 1% CS. Reabsorption and noncytotoxic property of optimized scaffold were established by enzymatic degradation and MTT assay. Enzymatic degradation suggested 20–45% of weight loss (WL) within 14 days of incubation. Cytotoxicity analysis showed that scaffolds were noncytotoxic against normal human dermal fibroblast human dermal fibroblast cell lines. Significant cellular adherence over the scaffold surface with normal cellular morphology was confirmed using SEM analysis. In vivo efficacy evaluation was carried out by means of reduction in wound size on Sprague-Dawley rats. Sprague-Dawley rats treated with optimized scaffold showed ~ 100% wound healing in comparison to ~80% healing in betadine-treated animals within 14 days. Histological examination depicted advance re-epithelization with better organization of collagen bundle in wound area treated with 2% CS in comparison to conventional treatment or no treatment. Conclusion: This study, thus, reveals that 2% CSs were found to have a great potential in wound healing. PMID:28216954

In Vitro Ultrastructural Changes of MCF-7 for Metastasise Bone Cancer and Induction of Apoptosis via Mitochondrial Cytochrome C Released by CaCO3/Dox Nanocrystals

PubMed Central

Shafiu Kamba, Abdullahi; Ismail, Maznah; Tengku Ibrahim, Tengku Azmi; Zakaria, Zuki Abu Bakar; Hassan Gusau, Lawal

2014-01-01

Bones are the most frequent site for breast cancer cells to settle and spread (metastasise); bone metastasis is considered to have a substantial impact on the quality of patients with common cancers. However, majority of breast cancers develop insensitivity to conventional chemotherapy which provides only palliation and can induce systemic side effects. In this study we evaluated the effect of free Dox and CaCO3/Dox nanocrystal on MCF-7 breast cancer using MTT (3-[4, 5-dimethylthiazol-2-yl]-2, 5-diphenyl tetrazolium bromide), neural red, and lactate dehydrogenase colorimetric assays while DNA fragmentation and BrdU genotoxicity were also examined. Apoptogenic protein Bax, cytochrome C, and caspase-3 protein were analysed. Morphological changes of MCF-7 were determined using contrast light microscope and scanning and transmission electron microscope (SEM and TEM). The findings of the analysis revealed higher toxicity of CaCO3/Dox nanocrystal and effective cells killing compared to free Dox, morphological changes such as formation of apoptotic bodies, membrane blebbing, and absent of microvilli as indicated by the SEM analysis while TEM revealed the presence of chromatin condensation, chromosomal DNA fragmentation, cell shrinkage, and nuclear fragmentation. Results of TUNEL assay verified that most of the cells undergoes apoptosis by internucleosomal fragmentation of genomic DNA whereas the extent of apoptotic cells was calculated using the apoptotic index (AI). Therefore, the biobased calcium carbonate nanocrystals such as Dox carriers may serve as an alternative to conventional delivery system. PMID:25028650

Magnetic properties and microstructure of gas atomized MRE2(Fe, Co)14B powder with ZrC addition (MRE=Nd + Y + Dy)

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

Tang, W.; Wu, Y. Q.; Dennis, K.

2009-05-12

Gas atomization powder with Zr substitutions for the MRE and ZrC additions were systematically studied. The results show that the partial substitutions of Zr and the ZrC additions effectively improved glass formability in the alloys. Scanning electron microscopy (SEM) revealed that the as-atomized powder with a particle size of less than 32 {micro}m is predominately uniform equiaxed grains with an average grain size of 1.5 {micro}m. X-ray diffraction and differential thermal analysis measurements detected very tiny amounts of amorphous phase. After annealing at 700 C for 15 min, the SEM grain microstructure exhibits a minor change, but magnetic properties aremore » substantially improved. M versus T measurements reveal that the phase composition evolved from 2:14:1 plus a small amount of 2:17 phases to a single 2:14:1 phase during the annealing process. The sieve analysis of the powders showed a particle size distribution with 90 wt % of the powder less than 45 {micro}m. The magnetic properties of the annealed powder varied with particle size. (BH){sub max} first increases with increasing particle size from 5 {micro}m, reaches the peak value in the size range of 20-25 {micro}m, and then decreases with increasing particle size. For the 20-25 {micro}m powder sample annealed at 700 C for 15 min, the (BH){sub max} of 9.6 MG Oe at room temperature and 5.6 MG Oe at 200 C were obtained, respectively.« less

Three-dimensional ultrastructure of osteocytes assessed by focused ion beam-scanning electron microscopy (FIB-SEM).

PubMed

Hasegawa, Tomoka; Yamamoto, Tomomaya; Hongo, Hiromi; Qiu, Zixuan; Abe, Miki; Kanesaki, Takuma; Tanaka, Kawori; Endo, Takashi; de Freitas, Paulo Henrique Luiz; Li, Minqi; Amizuka, Norio

2018-04-01

The aim of this study is to demonstrate the application of focused ion beam-scanning electron microscopy, FIB-SEM for revealing the three-dimensional features of osteocytic cytoplasmic processes in metaphyseal (immature) and diaphyseal (mature) trabeculae. Tibiae of eight-week-old male mice were fixed with aldehyde solution, and treated with block staining prior to FIB-SEM observation. While two-dimensional backscattered SEM images showed osteocytes' cytoplasmic processes in a fragmented fashion, three-dimensional reconstructions of FIB-SEM images demonstrated that osteocytes in primary metaphyseal trabeculae extended their cytoplasmic processes randomly, thus maintaining contact with neighboring osteocytes and osteoblasts. In contrast, diaphyseal osteocytes extended thin cytoplasmic processes from their cell bodies, which ran perpendicular to the bone surface. In addition, these osteocytes featured thick processes that branched into thinner, transverse cytoplasmic processes; at some point, however, these transverse processes bend at a right angle to run perpendicular to the bone surface. Osteoblasts also possessed thicker cytoplasmic processes that branched off as thinner processes, which then connected with cytoplasmic processes of neighboring osteocytes. Thus, FIB-SEM is a useful technology for visualizing the three-dimensional structures of osteocytes and their cytoplasmic processes.

Synthesis and structural characterization of polyaniline/cobalt chloride composites

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

Asha, E-mail: arana5752@gmail.com; Goyal, Sneh Lata; Kishore, Nawal

2016-05-23

Polyaniline (PANI) and PANI /cobalt chloride composites were synthesized by in situ chemical oxidative polymerization of aniline with CoCl{sub 2}.6H{sub 2}O using ammonium peroxidisulphate as an oxidant. These composites were characterized by X-ray diffraction (XRD) and Scanning electron microscopy (SEM). The XRD study reveals that both PANI and composites are amorphous. The XRD and SEM results confirm the presence of cobalt chloride in the composites.

Freeze-fracture of infected plant leaves in ethanol for scanning electron microscopic study of fungal pathogens.

PubMed

Moore, Jayma A; Payne, Scott A

2012-01-01

Fungi often are found within plant tissues where they cannot be visualized with the scanning electron microscope (SEM). We present a simple way to reveal cell interiors while avoiding many common causes of artifact. Freeze-fracture of leaf tissue using liquid nitrogen during the 100% ethanol step of the dehydration process just before critical point drying is useful in exposing intracellular fungi to the SEM.

Stent migration following endoscopic suture fixation of esophageal self-expandable metal stents: a systematic review and meta-analysis.

PubMed

Law, Ryan; Prabhu, Anoop; Fujii-Lau, Larissa; Shannon, Carol; Singh, Siddharth

2018-02-01

Covered self-expandable metal stents (SEMS) are utilized for the management of benign and malignant esophageal conditions; however, covered SEMS are prone to migration. Endoscopic suture fixation may mitigate the migration risk of covered esophageal SEMS. Hence, we conducted a systematic review and meta-analysis to evaluate the effectiveness and safety of endoscopic suture fixation for covered esophageal SEMS. Following PRISMA guidelines, we performed a systematic review from 2011 to 2016 to identify studies (case control/case series) reporting the technical success and migration rate of covered esophageal SEMS following endoscopic suture fixation. We searched multiple electronic databases and conference proceedings. We calculated pooled rates (and 95% confidence intervals [CI]) of technical success and stent migration using a random effects model. We identified 14 studies (212 patients) describing covered esophageal SEMS placement with endoscopic suture fixation. When reported, SEMS indications included leak/fistula (n = 75), stricture (n = 65), perforation (n = 10), and achalasia (n = 4). The pooled technical success rate was 96.7% (95% CI 92.3-98.6), without heterogeneity (I 2  = 0%). We identified 29 SEMS migrations at rate of 15.9% (95% CI 11.4-21.6), without heterogeneity (I 2  = 0%). Publication bias was observed, and using the trim-and-fill method, a more conservative estimate for stent migration was 17.0%. Suture-related adverse events were estimated to occur in 3.7% (95% CI 1.6-8.2) of cases. Endoscopic suture fixation of covered esophageal SEMS appears to reduce stent migration when compared to published rates of non-anchored SEMS. However, SEMS migration still occurs in approximately 1 out of 6 cases despite excellent immediate technical success and low risk of suture-related adverse events.

Monodispersed fabrication and dielectric studies on ethylenediamine passivated α-manganese dioxide nanorods

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

Joseph, A. Martin; Kumar, R. Thilak, E-mail: manojthilak@yahoo.com

2016-09-15

Highlights: • Monodispersed ethylenediamine (EDA) passivated α-MnO{sub 2} nanorods were fabricated by inexpensive wet chemical method. • FTIR analysis indicated that surface passivation is strongly influenced by the introduction of the organic ligand. • XRD and HR-SEM revealed the structure and morphology of the fabricated α-MnO{sub 2} nanorods with an average size of about 40 × 200 nm. • Dielectric studies pointed out that the fabricated α-MnO{sub 2} is semiconducting in nature with resistivity, ρ = 1.46 to 5.76 × 10{sup 3} Ωcm. • The optical energy gap for the fabricated α-MnO{sub 2} nanorods is found to be around 1.37more » eV. - Abstract: In this present work, pure α-MnO{sub 2} nanorods were fabricated by the reduction of 0.2 m/L of KMnO{sub 4} with 0.2 m/L of Na{sub 2}S{sub 2}O{sub 3}·5H{sub 2}O and by passivating with the organic ligand Ethylenediamine (EDA). The structural, functional, morphological and chemical composition of the nanorods were investigated by X-Ray Diffractometer (XRD), Fourier Transform Infrared Spectrometer (FTIR), High Resolution Scanning Electron Microscope (HR-SEM) and Energy Dispersive X-Ray Spectrometry (EDX). The XRD analysis indicated high crystalline nature of the product and FTIR confirmed the contribution of the organic ligand in surface passivation. HR-SEM image revealed the morphology of the α-MnO{sub 2} nanorods with an average size of about 40 × 200 nm. EDX confirmed the presence of Mn and O in the material. UV–visible spectrophotometery was used to determine the absorption behavior of the nanorods and an indirect band gap of 1.37 eV was acquired by Taucplot. Dielectric studies were carried out using Broadband Dielectric Spectrometer(BDS) and the resistivity was found to be around the semiconductor range (ρ = 1.46 to 5.76 × 10{sup 3} Ωcm).« less

Sharing of secondary electrons by in-lens and out-lens detector in low-voltage scanning electron microscope equipped with immersion lens.

PubMed

Kumagai, Kazuhiro; Sekiguchi, Takashi

2009-03-01

To understand secondary electron (SE) image formation with in-lens and out-lens detector in low-voltage scanning electron microscopy (LV-SEM), we have evaluated SE signals of an in-lens and an out-lens detector in LV-SEM. From the energy distribution spectra of SEs with various boosting voltages of the immersion lens system, we revealed that the electrostatic field of the immersion lens mainly collects electrons with energy lower than 40eV, acting as a low-pass filter. This effect is also observed as a contrast change in LV-SEM images taken by in-lens and out-lens detectors.

MnMoO4 nanolayers : Synthesis characterizations and electrochemical detection of QA

NASA Astrophysics Data System (ADS)

Muthamizh, S.; Kumar, S. Praveen; Munusamy, S.; Narayanan, V.

2018-04-01

MnMoO4 nanolayers were prepared by precipitation method. The MnMoO4 nanolayers were synthesized by using commercially available (CH3COO)2Mn.4H2O and Na2WO4.2H2O. The XRD pattern reveals that the synthesized MnMoO4 has monoclinic structure. In addition, lattice parameter values were also calculated using XRD data. The Raman analysis confirm the presence of Mo-O in MnMoO4 nanolayers. DRS-UV analysis shows that MnMoO4 has a band gap of 2.59 eV. FE-SEM and HR-TEM analysis along with EDAX confirms the material morphology in stacked layers like structure in nano scale. Synthesized nanolayers were utilized for the detection of biomolecule quercetin (QA).

Simulation of FIB-SEM images for analysis of porous microstructures.

PubMed

Prill, Torben; Schladitz, Katja

2013-01-01

Focused ion beam nanotomography-scanning electron microscopy tomography yields high-quality three-dimensional images of materials microstructures at the nanometer scale combining serial sectioning using a focused ion beam with SEM. However, FIB-SEM tomography of highly porous media leads to shine-through artifacts preventing automatic segmentation of the solid component. We simulate the SEM process in order to generate synthetic FIB-SEM image data for developing and validating segmentation methods. Monte-Carlo techniques yield accurate results, but are too slow for the simulation of FIB-SEM tomography requiring hundreds of SEM images for one dataset alone. Nevertheless, a quasi-analytic description of the specimen and various acceleration techniques, including a track compression algorithm and an acceleration for the simulation of secondary electrons, cut down the computing time by orders of magnitude, allowing for the first time to simulate FIB-SEM tomography. © Wiley Periodicals, Inc.

Effect of TiO2 Nanofiller Concentration on the Mechanical, Thermal and Biological Properties of HDPE/TiO2 Nanocomposites

NASA Astrophysics Data System (ADS)

Mozumder, Mohammad Sayem; Mourad, Abdel-Hamid I.; Mairpady, Anusha; Pervez, Hifsa; Haque, Md Emdadul

2018-03-01

The necessity for advanced and effective biomimetic tissue engineering materials has increased massively as bone diseases such as osteoporosis and bone cancer have become a major public health problem. Therefore, the objective of this study is to develop titanium dioxide (TiO2) nanoparticles-enriched high-density polyethylene (HDPE) nanocomposites that could serve as potential biomaterials. HDPE/TiO2 nanocomposites with varying TiO2 nanoparticles content were fabricated by using injection molding technique and were subjected to mechanical, thermal and biological characterization. SEM-EDS analysis confirmed even dispersion of TiO2 nanoparticles into the HDPE matrix. It was observed from the mechanical testing that the addition of TiO2 nanoparticles to HDPE noticeably improved the stiffness (from 345 to 378 MPa) while maintaining almost similar yield strength of pure HDPE. The thermal analyses revealed that TiO2 nanoparticles inclusion to HDPE matrix enhanced the thermal stability of nanocomposites, as the overall rate of crystallization increased by almost 4%. Furthermore, biocompatibility of nanocomposites was also studied by means of various cell culture experiments; human osteoblasts (hFOB) were seeded on the HDPE/TiO2 nanocomposites and were visualized through SEM after 72 h of incubation; surface morphology revealed normal cell growth and spreading with more attachment on PNC-10 that contains 10 wt.% of TiO2. Moreover, cell viability assays (i.e., MTT and cell attachment) revealed consistent increase in cell count and metabolic activity when triplicate cultures were incubated for 1, 3 and 7 days.

Effect of TiO2 Nanofiller Concentration on the Mechanical, Thermal and Biological Properties of HDPE/TiO2 Nanocomposites

NASA Astrophysics Data System (ADS)

Mozumder, Mohammad Sayem; Mourad, Abdel-Hamid I.; Mairpady, Anusha; Pervez, Hifsa; Haque, Md Emdadul

2018-05-01

The necessity for advanced and effective biomimetic tissue engineering materials has increased massively as bone diseases such as osteoporosis and bone cancer have become a major public health problem. Therefore, the objective of this study is to develop titanium dioxide (TiO2) nanoparticles-enriched high-density polyethylene (HDPE) nanocomposites that could serve as potential biomaterials. HDPE/TiO2 nanocomposites with varying TiO2 nanoparticles content were fabricated by using injection molding technique and were subjected to mechanical, thermal and biological characterization. SEM-EDS analysis confirmed even dispersion of TiO2 nanoparticles into the HDPE matrix. It was observed from the mechanical testing that the addition of TiO2 nanoparticles to HDPE noticeably improved the stiffness (from 345 to 378 MPa) while maintaining almost similar yield strength of pure HDPE. The thermal analyses revealed that TiO2 nanoparticles inclusion to HDPE matrix enhanced the thermal stability of nanocomposites, as the overall rate of crystallization increased by almost 4%. Furthermore, biocompatibility of nanocomposites was also studied by means of various cell culture experiments; human osteoblasts (hFOB) were seeded on the HDPE/TiO2 nanocomposites and were visualized through SEM after 72 h of incubation; surface morphology revealed normal cell growth and spreading with more attachment on PNC-10 that contains 10 wt.% of TiO2. Moreover, cell viability assays (i.e., MTT and cell attachment) revealed consistent increase in cell count and metabolic activity when triplicate cultures were incubated for 1, 3 and 7 days.

EVALUATION OF COMPUTER-CONTROLLED SCANNING ELECTRON MICROSCOPY APPLIED TO AN AMBIENT URBAN AEROSOL SAMPLE

EPA Science Inventory

Recent interest in monitoring and speciation of particulate matter has led to increased application of scanning electron microscopy (SEM) coupled with energy-dispersive x-ray analysis (EDX) to individual particle analysis. SEM/EDX provides information on the size, shape, co...

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.

A study of the UV and VUV degradation of FEP

NASA Technical Reports Server (NTRS)

George, Graeme A.; Hill, David J. T.; Odonnell, James H.; Pomery, Peter J.; Rasoul, Firas A.

1993-01-01

UV and VUV degradation of fluorinated ethylene propylene (FEP) copolymer was studied using electron spin resonance (ESR) spectroscopy, x-ray photoelectron spectroscopy (XPS), and scanning electron microscopy (SEM). The ESR study revealed the formation of a terminal polymer radical. The stability of this radical was investigated under different environments. An XPS study of FEP film exposed to VUV and atomic oxygen showed that oxidation takes place on the polymer surface. The study revealed also that the percentage of CF2 in the polymer surface decreased with exposure time and the percentage of CF, CF3, and carbon attached to oxygen increased. SEM micrographs of FEP film exposed to VUV and atomic oxygen identified a rough surface with undulations similar to sand dunes.

The advancement of the built environment research through employment of structural equation modeling (SEM)

NASA Astrophysics Data System (ADS)

Wasilah, S.; Fahmyddin, T.

2018-03-01

The employment of structural equation modeling (SEM) in research has taken an increasing attention in among researchers in built environment. There is a gap to understand the attributes, application, and importance of this approach in data analysis in built environment study. This paper intends to provide fundamental comprehension of SEM method in data analysis, unveiling attributes, employment and significance and bestow cases to assess associations amongst variables and constructs. The study uses some main literature to grasp the essence of SEM regarding with built environment research. The better acknowledgment of this analytical tool may assist the researcher in the built environment to analyze data under complex research questions and to test multivariate models in a single study.

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

Guener, M.; Gueler, E.; Aktas, H.

Kinetic, morphological and some thermal properties of thermally induced and deformation-induced martensite were studied in a Fe-32%Ni-0.4%Cr alloy. Scanning electron microscopy (SEM), differential scanning calorimetry (DSC) and compression deformation test techniques were used for these studies. SEM observations revealed the occurrence of both athermal and isothermal martensitic transformation kinetics for producing a lenticular martensite morphology for different homogenization conditions of the prior austenite phase. The DSC measurement results showed a fair agreement with those of previous studies on ferrous alloys.

SD-SEM: sparse-dense correspondence for 3D reconstruction of microscopic samples.

PubMed

Baghaie, Ahmadreza; Tafti, Ahmad P; Owen, Heather A; D'Souza, Roshan M; Yu, Zeyun

2017-06-01

Scanning electron microscopy (SEM) imaging has been a principal component of many studies in biomedical, mechanical, and materials sciences since its emergence. Despite the high resolution of captured images, they remain two-dimensional (2D). In this work, a novel framework using sparse-dense correspondence is introduced and investigated for 3D reconstruction of stereo SEM images. SEM micrographs from microscopic samples are captured by tilting the specimen stage by a known angle. The pair of SEM micrographs is then rectified using sparse scale invariant feature transform (SIFT) features/descriptors and a contrario RANSAC for matching outlier removal to ensure a gross horizontal displacement between corresponding points. This is followed by dense correspondence estimation using dense SIFT descriptors and employing a factor graph representation of the energy minimization functional and loopy belief propagation (LBP) as means of optimization. Given the pixel-by-pixel correspondence and the tilt angle of the specimen stage during the acquisition of micrographs, depth can be recovered. Extensive tests reveal the strength of the proposed method for high-quality reconstruction of microscopic samples. Copyright © 2017 Elsevier Ltd. All rights reserved.

Difficult removal of fully covered self expandable metal stents (SEMS) for benign biliary strictures: the "SEMS in SEMS" technique.

PubMed

Tringali, Andrea; Blero, Daniel; Boškoski, Ivo; Familiari, Pietro; Perri, Vincenzo; Devière, Jacques; Costamagna, Guido

2014-06-01

Removal of biliary Fully Covered Self Expandable Metal Stents can fail due to stent migration and/or hyperplastic ingrowth/overgrowth. A case series of 5 patients with benign biliary strictures (2 post-cholecystectomy, 2 following liver transplantation and 1 related to chronic pancreatitis) is reported. The biliary stricture was treated by temporary insertion of Fully Covered Self Expandable Metal Stents. Stent removal failed due to proximal stent migration and/or overgrowth. Metal stent removal was attempted a few weeks after the insertion of another Fully Covered Metal Stent into the first one. The inner Fully Covered Self Expandable Metal Stent compressed the hyperplastic tissue, leading to the extraction of both the stents in all cases. Two complications were reported as a result of the attempt to stents removal (mild pancreatitis and self-limited haemobilia). In the present series, the "SEMS in SEMS" technique revealed to be effective when difficulties are encountered during Fully Covered Self Expandable Metal Stents removal. Copyright © 2014 Editrice Gastroenterologica Italiana S.r.l. Published by Elsevier Ltd. All rights reserved.

Development and Evaluation of Cefadroxil Drug Loaded Biopolymeric Films Based on Chitosan-Furfural Schiff Base

PubMed Central

Dixit, Ritu B.; Uplana, Rahul A.; Patel, Vishnu A.; Dixit, Bharat C.; Patel, Tarosh S.

2010-01-01

Cefadroxil drug loaded biopolymeric films of chitosan-furfural schiff base were prepared by reacting chitosan with furfural in presence of acetic acid and perchloric acid respectively for the external use. Prepared films were evaluated for their strength, swelling index, thickness, drug content, uniformity, tensile strength, percent elongation, FTIR spectral analysis and SEM. The results of in vitro diffusion studies revealed that the films exhibited enhanced drug diffusion as compared to the films prepared using untreated chitosan. The films also demonstrated good to moderate antibacterial activities against selective gram positive and gram negative bacteria. PMID:21179325

Petrographic studies of refractory inclusions from the Murchison meteorite

NASA Technical Reports Server (NTRS)

Macpherson, G. J.; Grossman, L.; Hashimoto, A.; Bar-Matthews, M.; Tanaka, T.

1984-01-01

Textural and mineral-chemical data on freeze-thaw disaggregated refractory inclusions from the Murchison meteorite are reported. The data were obtained with neutron activation analysis, SEM, and spectroscopy, the study revealed corundum-bearing inclusions, spinel-hibonite aggregates and spherules, and spinel-pyroxene and elivine-pyroxene inclusions. One of the three spinel-, pyroxene-, forsterite-rich inclusions had an amoeba-shaped spinel-pyroxene core, implying vapor-to-solid condensation and therefore crystallization from a melt. It is concluded that the meteorite formation encompassed diverse nebular materials, and that further studies of the meteorite will enhance the data base on the planetary nebular processes.

Experimental Characterization of Aluminum-Based Hybrid Composites Obtained Through Powder Metallurgy

NASA Astrophysics Data System (ADS)

Marcu, D. F.; Buzatu, M.; Ghica, V. G.; Petrescu, M. I.; Popescu, G.; Niculescu, F.; Iacob, G.

2018-06-01

The paper presents some experimental results concerning fabrication through powder metallurgy (P/M) of aluminum-based hybrid composites - Al/Al2O3/Gr. In order to understand the mechanisms that occur during the P/M processes of obtaining Al/Al2O3/Gr composite, we correlated the physical characteristics with their micro-structural characteristics. The characterization was performed using analysis techniques specific for P/M process, SEM-EDS and XRD analyses. Micro-structural characterization of the composites has revealed fairly uniform distribution this resulting in good properties of the final composite material.

Formation Mechanism of Spherical TiC in Ni-Ti-C System during Combustion Synthesis.

PubMed

Zhu, Guoliang; Wang, Wei; Wang, Rui; Zhao, Chuanbao; Pan, Weitao; Huang, Haijun; Du, Dafan; Wang, Donghong; Shu, Da; Dong, Anping; Sun, Baode; Jiang, Sheng; Pu, Yilong

2017-08-29

The formation mechanism of TiC particles in a Ni-Ti-C system were revealed by using differential thermal analysis (DTA), XRD, and SEM to identify the reaction products in different temperature ranges. The results indicated that the synthesis mechanism of TiC in Ni-Ti-C system was complex; several reactions were involved in the combustion synthesis of TiC-Ni composite. The Ni-Ti intermediate phases play important roles during the formation of TiC. Moreover, the influence of heating rate on the size range of TiC was also discussed.

Formation Mechanism of Spherical TiC in Ni-Ti-C System during Combustion Synthesis

PubMed Central

Zhu, Guoliang; Wang, Wei; Wang, Rui; Zhao, Chuanbao; Pan, Weitao; Huang, Haijun; Du, Dafan; Wang, Donghong; Shu, Da; Dong, Anping; Sun, Baode; Jiang, Sheng; Pu, Yilong

2017-01-01

The formation mechanism of TiC particles in a Ni-Ti-C system were revealed by using differential thermal analysis (DTA), XRD, and SEM to identify the reaction products in different temperature ranges. The results indicated that the synthesis mechanism of TiC in Ni-Ti-C system was complex; several reactions were involved in the combustion synthesis of TiC-Ni composite. The Ni-Ti intermediate phases play important roles during the formation of TiC. Moreover, the influence of heating rate on the size range of TiC was also discussed. PMID:28850088

Synthesis and Characterization of Molybdenum (Mo) Thin Films Using DC-Magnetron Sputtering

NASA Astrophysics Data System (ADS)

Pandharkar, Subhash M.; Rondiya, Sachin R.; Rokade, Avinash V.; Gabhale, Bharat B.; Pathan, Habib M.; Jadkar, Sandesh R.

2018-03-01

In present work, we report synthesis of Mo thin films by DC-magnetron sputtering method. The structural, optical, morphological and electrical properties were investigated as a function of target-to-substrate distance. From the results, it is evident that with increase in target-to-substrate distance the thickness of films decreases while its sheet resistance and electrical resistivity increases, which is confirmed by van der Pauw method. Low angle XRD analysis revealed that with increase in target-to-substrate distance preferred orientation of Mo crystallites changes from (211) to (110) and its size decreases. The FE-SEM analysis revealed a significant change in surface morphology with increase in target-to-substrate distance. UV-Visible spectroscopy analysis showed that Mo films deposited at high target-to-substrate distance have more reflection than those deposited at lower target-to-substrate. Finally, adhesion test was performed using scotch hatch tape adhesion test which show all Mo films have excellent adhesion over the entire range of target-to-substrate distance studied. The employment of such Mo films as back contact can be useful to improve efficiency of CZTS solar cells.

Graft polymerization of guar gum with acryl amide irradiated by microwaves for colonic drug delivery.

PubMed

Shahid, Muhammad; Bukhari, Shazia Anwer; Gul, Yousra; Munir, Hira; Anjum, Fozia; Zuber, Mohammad; Jamil, Tahir; Zia, Khalid Mahmood

2013-11-01

This article is aimed to discuss the modification of guar gum through microwave irradiation by varying the time of irradiation. The characterization of the modified products was carried out using FTIR spectroscopic analysis. The FT-IR spectrum of the pure guar gum (GG) sample showed a broad peak at 3298 cm(-1) while the modified GG sample displayed a peak at 1541 cm(-1) which was absent in the crude sample. The X-ray diffraction (XRD) analysis confirmed the increase in crystallinity due to grafting of the sample with polyacrylamide (GG-g-PAM). Scanning electron microscope (SEM) images revealed that granular form of guar gum was changed into fibrillar structure after grafting. Thermo-gravimetric analysis of the modified samples was also carried out and discussed. The role of guar gum as a matrix for controlled release of drug triamcinolone was evaluated. The GG-acrylamide grafted samples presented a correlation between drug release and time of microwave exposure. The results revealed that such modified product has potential applications in colonic drug delivery system. Copyright © 2013 Elsevier B.V. All rights reserved.

Effect of catalyst on deposition of vanadium oxide in plasma ambient

NASA Astrophysics Data System (ADS)

Singh, Megha; Kumar, Prabhat; Saini, Sujit K.; Reddy, G. B.

2018-05-01

In this paper, we have studied effect of catalyst (buffer layer) on structure, morphology, crystallinity, uniformity of nanostructured thin films deposited in nitrogen plasma ambient keeping all other process parameters constant. The process used for deposition is novel known as Plasma Assisted Sublimation Process (PASP). Samples were then studied using SEM, TEM, HRTEM, Raman spectroscopy. By structural analysis it was found out that samples deposited on Ni layer composed chiefly of α-V2O5 but minor amount of other phases were present in the sample. Samples deposited on Al catalyst layer revealed different phase of V2O5, where sample deposited on Ag was composed chiefly of VO2±x phase. Further analysis revealed that morphology of samples is also affected by catalyst. While samples deposited in Al and Ag layer tend to have reasonably defined geometry, sample deposited on Ni layer were irregular in shape and size. All the results well corroborate with each other.

Evaluation of microwave-assisted pretreatment of lignocellulosic biomass immersed in alkaline glycerol for fermentable sugars production.

PubMed

Diaz, Ana Belen; Moretti, Marcia Maria de Souza; Bezerra-Bussoli, Carolina; Carreira Nunes, Christiane da Costa; Blandino, Ana; da Silva, Roberto; Gomes, Eleni

2015-06-01

A pretreatment with microwave irradiation was applied to enhance enzyme hydrolysis of corn straw and rice husk immersed in water, aqueous glycerol or alkaline glycerol. Native and pretreated solids underwent enzyme hydrolysis using the extract obtained from the fermentation of Myceliophthora heterothallica, comparing its efficiency with that of the commercial cellulose cocktail Celluclast®. The highest saccharification yields, for both corn straw and rice husk, were attained when biomass was pretreated in alkaline glycerol, method that has not been previously reported in literature. Moreover, FTIR, TG and SEM analysis revealed a more significant modification in the structure of corn straw subjected to this pretreatment. Highest global yields were attained with the crude enzyme extract, which might be the result of its content in a great variety of hydrolytic enzymes, as revealed zymogram analysis. Moreover, its hydrolysis efficiency can be improved by its supplementation with commercial β-glucosidase. Copyright © 2015 Elsevier Ltd. All rights reserved.

AES and SIMS analysis of non-metallic inclusions in a low-carbon chromium-steel.

PubMed

Gammer, Katharina; Rosner, M; Poeckl, G; Hutter, H

2003-05-01

In the final step of secondary metallurgical steel processing, calcium is added. Besides Mg, Ca is the most powerful deoxidiser and desulfurisation agent. It reacts with dissolved oxygen and sulfur and reduces oxides and sulfides thereby forming non-metallic inclusions. Within this paper we present the analysis of such inclusions in a low-carbon chromium-steel. Depending on the time of quenching of the steel sample, different structures were revealed by REM, Auger and SIMS: If the steel was quenched immediately after Ca-addition, non-metallic inclusions that appeared to have "cavities" could be detected with SEM. SIMS investigations of these particles showed ring-shaped structures and revealed that the ring is made up of Al, Ca, Mg, O and S. No secondary ions however could be retrieved from the core inside the ring, thus leaving the nature of the "cavities" unclear. If the steel sample was quenched 3 min after Ca addition, inclusions did not have a ring-shaped structure but a compact one.

The effect of CO2 and Nd:YAP lasers on CAD/CAM Ceramics: SEM, EDS and thermal studies

PubMed Central

Fornaini, Carlo; Rocca, Jean Paul; Muhammad, Omid H; Medioni, Etienne; Cucinotta, Annamaria; Brulat-Bouchard, Nathalie

2016-01-01

Background and aims: The objective of this study was to investigate the interaction of infrared laser light on Computer Aided Design and Computer Aided Manufacturing (CAD/CAM) ceramic surfaces. Material and Methods: Sixty CAD/CAM ceramic discs were prepared and divided into two different groups: lithiumdisilicate ceramic (IPSe.maxCADs) and Zirconia ceramic (IPSe.maxZirCADs). The laser irradiation was performed on graphite and non-graphite surfaces with a Carbon Dioxide laser at 5W and 10W power in continuous mode (CW mode) and with Neodymium Yttrium Aluminum Perovskite (Nd:YAP) laser at 10W. Surface textures and compositions were examined using Scanning Electron Microscopy (SEM), and Energy Dispersive Spectroscopy (EDS). Thermal elevation was measured by thermocouple during laser irradiation. Results: The SEM observation showed a rough surface plus cracks and fissures on CO2 10W samples and melting areas in Nd:YAP samples; moreover, with CO2 5W smooth and shallow surfaces were observed. EDS analysis revealed that laser irradiation does not result in modifications of the chemical composition even if minor changes in the atomic mass percentage of the components were registered. Thermocouple showed several thermal changes during laser irradiation. Conclusion: CO2 and Nd:YAP lasers modify CAD/CAM ceramic surface without chemical composition modifications. PMID:27141152

Importance-Performance Matrix Analysis (IPMA) Of Transport Disadvantage Variables on Social Exclusion in a Rural Context

NASA Astrophysics Data System (ADS)

Larasati, Ophilia; Puspita Dirgahayani, Eng., Dr.

2018-05-01

Transport services are essential to support daily life. A lack of transport supply leads to the existence of transport disadvantaged (TDA) groups who are vulnerable to social exclusion, which happens when a particular group or individual is having difficulties to access certain activities that are considered normal in society. To tackle this phenomenon, the understanding of the influence of TDA variables on social exclusion is needed. The aim of this study is to analyze the influences of TDA variables on social exclusion in a rural context, with Cibeureum Village (Bandung Barat Regency) and Bunikasih Village (Subang Regency) as the study case. Both case studies provide different characteristics of accessibility. Partial Least Squares (PLS) Structural Equation Modeling (SEM) is chosen as the method to analyze the influences of TDA variables on social exclusion. The PLS-SEM model is developed according to the social exclusion variable and four TDA variables, i.e., accessibility, individual characteristics, private vehicle existence, and travel behavior. IPMA is done after the PLS-SEM model is evaluated. The study reveals that among four of the TDA variables, accessibility has the most influence on social exclusion, hence interventions related to improving accessibility are needed to tackle social exclusion. More specifically, the provision of alternative modes is needed in both study areas, while in Bunikasih Village the cost of travel is also an important variable to consider.

Identification of possible sources of particulate matter in the personal cloud using SEM/EDX

NASA Astrophysics Data System (ADS)

Conner, Teri L.; Williams, Ronald W.

2004-10-01

The United States Environmental Protection Agency (US EPA) conducted the Baltimore Particulate Matter (PM) Epidemiology-Exposure Study of the Elderly during the summer of 1998. The study design included PM2.5 samples obtained from elderly (65+ years of age) retirement facility residents using personal exposure sampling devices. These sampling devices were also used to obtain PM2.5 samples at fixed locations within the personal monitoring subjects' apartments. Selected personal and apartment samples were examined using scanning electron microscopy with individual-particle X-ray analysis (SEM/EDX), providing a qualitative assessment of the chemical and physical characteristics of geological and trace element particles collected within these micro-environments at the retirement facility. This information was used to identify possible indoor source particles. The manual surveys of the personal samples revealed that some particles larger than 2.5 μm reached the filter surface. Using SEM/EDX, several particle types with possible indoor origins were identified. The Al-Zr-Cl particle is likely to have originated from a personal antiperspirant product. Particles with a talc or alumino-silicate composition point to cosmetics as a possible source. Large cadmium-containing particles were also found, which may indicate the use of art pigments or ceramic glazes, or emissions from television screen phosphors. A greater variety of particles was observed in a personal sample compared with its corresponding fixed-location apartment sample.

Evaluation of environmental scanning electron microscopy for analysis of Proteus mirabilis crystalline biofilms in situ on urinary catheters.

PubMed

Holling, Nina; Dedi, Cinzia; Jones, Caroline E; Hawthorne, Joseph A; Hanlon, Geoffrey W; Salvage, Jonathan P; Patel, Bhavik A; Barnes, Lara M; Jones, Brian V

2014-06-01

Proteus mirabilis is a common cause of catheter-associated urinary tract infections and frequently leads to blockage of catheters due to crystalline biofilm formation. Scanning electron microscopy (SEM) has proven to be a valuable tool in the study of these unusual biofilms, but entails laborious sample preparation that can introduce artefacts, undermining the investigation of biofilm development. In contrast, environmental scanning electron microscopy (ESEM) permits imaging of unprocessed, fully hydrated samples, which may provide much insight into the development of P. mirabilis biofilms. Here, we evaluate the utility of ESEM for the study of P. mirabilis crystalline biofilms in situ, on urinary catheters. In doing so, we compare this to commonly used conventional SEM approaches for sample preparation and imaging. Overall, ESEM provided excellent resolution of biofilms formed on urinary catheters and revealed structures not observed in standard SEM imaging or previously described in other studies of these biofilms. In addition, we show that energy-dispersive X-ray spectroscopy (EDS) may be employed in conjunction with ESEM to provide information regarding the elemental composition of crystalline structures and demonstrate the potential for ESEM in combination with EDS to constitute a useful tool in exploring the mechanisms underpinning crystalline biofilm formation. © 2014 The Authors. FEMS Microbiology Letters published by John Wiley & Sons Ltd on behalf of Federation of European Microbiological Societies.

[Stabilization Treatment of Pb and Zn in Contaminated Soils and Mechanism Studies].

PubMed

Xie, Wei-qiang; Li, Xiao-mingi; Chen, Can; Chen, Xun-feng; Zhong, Yu; Zhong, Zhen-yu; Wan, Yong; Wang, Yan

2015-12-01

In the present work, the combined application of potassium dihydrogen phosphate, quick lime and potassium chloride was used to immobilize the Pb and Zn in contaminated soils. The efficiency of the process was evaluated through leaching tests and Tessier sequential extraction procedure. The mechanism of stabilization was analyzed by X-ray diffraction (XRD) and scanning electron microscope (SEM) to reveal the mechanism of stabilization. The results showed that the stabilizing efficiency of Pb contaminated soils was above 80% and the leaching concentrations of Pb, Zn were far below the threshold when the ratio of exogenous P and soil (mol · mol⁻¹) was 2:1-4: 1, the dosing ratio of CaO was 0.1%-0.5% ( mass fraction) and the dosage of potassium chloride was 0.02-0. 04 mol. Meanwhile, Pb and Zn in soil were transformed from the exchangeable fraction into residual fraction, which implied that the migration of Pb, Zn in soil could be confined by the stabilization treatment. XRD and SEM analysis revealed that Ca-P-Pb precipitation, lead orthophosphate [PbHP0₄, Pb₃ (PO₄)₂], pyromorphite (Pb-PO₄-Cl/OH) and mixed heavy metal deposits (Fe-PO₄- Ca-Pb-Zn-OH) could be formed after solidification/stabilization in which Pb and Zn could be wrapped up to form a solidified composition and to prevent leaching.

Microsponges based novel drug delivery system for augmented arthritis therapy

PubMed Central

Osmani, Riyaz Ali M.; Aloorkar, Nagesh H.; Ingale, Dipti J.; Kulkarni, Parthasarathi K.; Hani, Umme; Bhosale, Rohit R.; Jayachandra Dev, Dandasi

2015-01-01

The motive behind present work was to formulate and evaluate gel containing microsponges of diclofenac diethylamine to provide prolonged release for proficient arthritis therapy. Quasi-emulsion solvent diffusion method was implied using Eudragit RS-100 and microsponges with varied drug–polymer ratios were prepared. For the sake of optimization, diverse factors affecting microparticles physical properties were too investigated. Microsponges were characterized by SEM, DSC, FT-IR, XRPD and particle size analysis, and evaluated for morphology, drug loading, in vitro drug release and ex vivo diffusion as well. There were no chemical interactions between drug and polymers used as revealed by compatibility studies outcomes. The drug polymer ratio reflected notable effect on drug content, encapsulation efficiency and particle size. SEM results revealed spherical microsponges with porous surface, and had 7.21 μm mean particle size. The microsponges were then incorporated in gel; which exhibited viscous modulus along with pseudoplastic behavior. In vitro drug release results depicted that microsponges with 1:2 drug–polymer ratio were more efficient to give extended drug release of 75.88% at the end of 8 h; while conventional formulation get exhausted incredibly earlier by releasing 81.11% drug at the end of 4 h only. Thus the formulated microsponge-based gel of diclofenac diethylamine would be a promising alternative to conventional therapy for safer and efficient treatment of arthritis and musculoskeletal disorders. PMID:26594124

Microsponges based novel drug delivery system for augmented arthritis therapy.

PubMed

Osmani, Riyaz Ali M; Aloorkar, Nagesh H; Ingale, Dipti J; Kulkarni, Parthasarathi K; Hani, Umme; Bhosale, Rohit R; Jayachandra Dev, Dandasi

2015-10-01

The motive behind present work was to formulate and evaluate gel containing microsponges of diclofenac diethylamine to provide prolonged release for proficient arthritis therapy. Quasi-emulsion solvent diffusion method was implied using Eudragit RS-100 and microsponges with varied drug-polymer ratios were prepared. For the sake of optimization, diverse factors affecting microparticles physical properties were too investigated. Microsponges were characterized by SEM, DSC, FT-IR, XRPD and particle size analysis, and evaluated for morphology, drug loading, in vitro drug release and ex vivo diffusion as well. There were no chemical interactions between drug and polymers used as revealed by compatibility studies outcomes. The drug polymer ratio reflected notable effect on drug content, encapsulation efficiency and particle size. SEM results revealed spherical microsponges with porous surface, and had 7.21 μm mean particle size. The microsponges were then incorporated in gel; which exhibited viscous modulus along with pseudoplastic behavior. In vitro drug release results depicted that microsponges with 1:2 drug-polymer ratio were more efficient to give extended drug release of 75.88% at the end of 8 h; while conventional formulation get exhausted incredibly earlier by releasing 81.11% drug at the end of 4 h only. Thus the formulated microsponge-based gel of diclofenac diethylamine would be a promising alternative to conventional therapy for safer and efficient treatment of arthritis and musculoskeletal disorders.

Preparation, characterisation and viability of encapsulated Trichoderma harzianum UPM40 in alginate-montmorillonite clay.

PubMed

Adzmi, Fariz; Meon, Sariah; Musa, Mohamed Hanafi; Yusuf, Nor Azah

2012-01-01

Microencapsulation is a process by which tiny parcels of an active ingredient are packaged within a second material for the purpose of shielding the active ingredient from the surrounding environment. This study aims to determine the ability of the microencapsulation technique to improve the viability of Trichoderma harzianum UPM40 originally isolated from healthy groundnut roots as effective biological control agents (BCAs). Alginate was used as the carrier for controlled release, and montmorillonite clay (MMT) served as the filler. The encapsulated Ca-alginate-MMT beads were characterised using Fourier transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA) and scanning electron microscopy (SEM). The FTIR results showed the interaction between the functional groups of alginate and MMT in the Ca-alginate-MMT beads. Peaks at 1595, 1420 and 1020 cm(-1) characterised alginate, and peaks at 1028 and 453 cm(-1) characterised MMT; both sets of peaks appeared in the Ca-alginate-MMT FTIR spectrum. The TGA analysis showed an improvement in the thermal stability of the Ca-alginate-MMT beads compared with the alginate beads alone. SEM analysis revealed a homogeneous distribution of the MMT particles throughout the alginate matrix. T. harzianum UPM40 was successfully encapsulated in the Ca-alginate-MMT beads. Storage analysis of the encapsulated T. harzianum UPM40 showed that the low storage temperature of 5°C resulted in significantly (p < 0.05) better storage compared with room temperature (30°C).

Titanium Ions Release from an Innovative Titanium-Magnesium Composite: an in Vitro Study.

PubMed

Stanec, Zlatko; Halambek, Jasna; Maldini, Krešimir; Balog, Martin; Križik, Peter; Schauperl, Zdravko; Ćatić, Amir

2016-03-01

The innovative titanium-magnesium composite (Ti-Mg) was produced by powder metallurgy (P/M) method and is characterized in terms of corrosion behavior. Two groups of experimental material, 1 mass% (Ti-1Mg) and 2 mass% (Ti-2Mg) of magnesium in titanium matrix, were tested and compared to commercially pure titanium (CP Ti). Immersion test and chemical analysis of four solutions: artificial saliva; artificial saliva pH 4; artificial saliva with fluoride and Hank balanced salt solution were performed after 42 days of immersion, using inductively coupled plasma mass spectrometry (ICP-MS) to detect the amount of released titanium ions (Ti). SEM and EDS analysis were used for surface characterization. The difference between the results from different test solutions was assessed by ANOVA and Newman-Keuls test at p<0.05. The influence of predictor variables was found by multiple regression analysis. The results of the present study revealed a low corrosion rate of titanium from the experimental Ti-Mg group. Up to 46 and 23 times lower dissolution of Ti from Ti-1Mg and Ti-2Mg, respectively was observed compared to the control group. Among the tested solutions, artificial saliva with fluorides exhibited the highest corrosion effect on all specimens tested. SEM micrographs showed preserved dual phase surface structure and EDS analysis suggested a favorable surface bioactivity. In conclusion, Ti-Mg produced by P/M as a material with better corrosion properties when compared to CP Ti is suggested.

Structural Equation Model Trees

PubMed Central

Brandmaier, Andreas M.; von Oertzen, Timo; McArdle, John J.; Lindenberger, Ulman

2015-01-01

In the behavioral and social sciences, structural equation models (SEMs) have become widely accepted as a modeling tool for the relation between latent and observed variables. SEMs can be seen as a unification of several multivariate analysis techniques. SEM Trees combine the strengths of SEMs and the decision tree paradigm by building tree structures that separate a data set recursively into subsets with significantly different parameter estimates in a SEM. SEM Trees provide means for finding covariates and covariate interactions that predict differences in structural parameters in observed as well as in latent space and facilitate theory-guided exploration of empirical data. We describe the methodology, discuss theoretical and practical implications, and demonstrate applications to a factor model and a linear growth curve model. PMID:22984789

Reliability of measuring sciatic and tibial nerve movement with diagnostic ultrasound during a neural mobilisation technique.

PubMed

Ellis, Richard; Hing, Wayne; Dilley, Andrew; McNair, Peter

2008-08-01

Diagnostic ultrasound provides a technique whereby real-time, in vivo analysis of peripheral nerve movement is possible. This study measured sciatic nerve movement during a "slider" neural mobilisation technique (ankle dorsiflexion/plantar flexion and cervical extension/flexion). Transverse and longitudinal movement was assessed from still ultrasound images and video sequences by using frame-by-frame cross-correlation software. Sciatic nerve movement was recorded in the transverse and longitudinal planes. For transverse movement, at the posterior midthigh (PMT) the mean value of lateral sciatic nerve movement was 3.54 mm (standard error of measurement [SEM] +/- 1.18 mm) compared with anterior-posterior/vertical (AP) movement of 1.61 mm (SEM +/- 0.78 mm). At the popliteal crease (PC) scanning location, lateral movement was 6.62 mm (SEM +/- 1.10 mm) compared with AP movement of 3.26 mm (SEM +/- 0.99 mm). Mean longitudinal sciatic nerve movement at the PMT was 3.47 mm (SEM +/- 0.79 mm; n = 27) compared with the PC of 5.22 mm (SEM +/- 0.05 mm; n = 3). The reliability of ultrasound measurement of transverse sciatic nerve movement was fair to excellent (Intraclass correlation coefficient [ICC] = 0.39-0.76) compared with excellent (ICC = 0.75) for analysis of longitudinal movement. Diagnostic ultrasound presents a reliable, noninvasive, real-time, in vivo method for analysis of sciatic nerve movement.

Effect of air polishing with glycine powder on titanium abutment surfaces.

PubMed

Cochis, Andrea; Fini, Milena; Carrassi, Antonio; Migliario, Mario; Visai, Livia; Rimondini, Lia

2013-08-01

The aim of the present study was to evaluate morphological changes induced by glycine powder air polishing on titanium surfaces and its effect on bacteria recolonization in comparison with sodium bicarbonate powder. 5 mm wide and 1 mm thick titanium grade II disks were divided into three groups of treatments: (i) no treatment; (ii) air polishing with glycine powder; (iii) air polishing with sodium bicarbonate powder. Specimens were characterized by laser profilometry, scanning electron microscopy (SEM) and then installed onto removable appliances worn for 24 h by healthy volunteers. Surface contamination was evaluated using SEM and counting the number of colony forming units (CFU). SEM observation revealed an increased roughness with the formation of craters on samples treated with sodium bicarbonate powder, while not in glycine ones. Statistical analysis failed to show significant differences of both Ra and Rmax parameters in treated groups. SEM observation of specimens surfaces, after 24 h of permanence in the oral cavity, showed a higher contamination of the disks treated with sodium bicarbonate compared with those not treated (P < 0.05). Conversely, the group treated with glycine showed the lower contamination if compared with bicarbonate-treated group (P < 0.05). Air polishing with glycine powder may be considered as a better method to remove plaque from dental implant because glycine is less aggressive than sodium bicarbonate powder. Moreover, the use of glycine powder seems to have an active role on the inhibition of bacterial recolonization of implants in a short test period (24 h). Further studies are needed to demonstrate the bacteriostatic properties of glycine, envisaged on the basis of reduced contamination of the disks polished with glycine compared with those not treated. © 2012 John Wiley & Sons A/S.

The reliability of three devices used for measuring vertical jump height.

PubMed

Nuzzo, James L; Anning, Jonathan H; Scharfenberg, Jessica M

2011-09-01

The purpose of this investigation was to assess the intrasession and intersession reliability of the Vertec, Just Jump System, and Myotest for measuring countermovement vertical jump (CMJ) height. Forty male and 39 female university students completed 3 maximal-effort CMJs during 2 testing sessions, which were separated by 24-48 hours. The height of the CMJ was measured from all 3 devices simultaneously. Systematic error, relative reliability, absolute reliability, and heteroscedasticity were assessed for each device. Systematic error across the 3 CMJ trials was observed within both sessions for males and females, and this was most frequently observed when the CMJ height was measured by the Vertec. No systematic error was discovered across the 2 testing sessions when the maximum CMJ heights from the 2 sessions were compared. In males, the Myotest demonstrated the best intrasession reliability (intraclass correlation coefficient [ICC] = 0.95; SEM = 1.5 cm; coefficient of variation [CV] = 3.3%) and intersession reliability (ICC = 0.88; SEM = 2.4 cm; CV = 5.3%; limits of agreement = -0.08 ± 4.06 cm). Similarly, in females, the Myotest demonstrated the best intrasession reliability (ICC = 0.91; SEM = 1.4 cm; CV = 4.5%) and intersession reliability (ICC = 0.92; SEM = 1.3 cm; CV = 4.1%; limits of agreement = 0.33 ± 3.53 cm). Additional analysis revealed that heteroscedasticity was present in the CMJ when measured from all 3 devices, indicating that better jumpers demonstrate greater fluctuations in CMJ scores across testing sessions. To attain reliable CMJ height measurements, practitioners are encouraged to familiarize athletes with the CMJ technique and then allow the athletes to complete numerous repetitions until performance plateaus, particularly if the Vertec is being used.

SEM-based overlay measurement between via patterns and buried M1 patterns using high-voltage SEM

NASA Astrophysics Data System (ADS)

Hasumi, Kazuhisa; Inoue, Osamu; Okagawa, Yutaka; Shao, Chuanyu; Leray, Philippe; Halder, Sandip; Lorusso, Gian; Jehoul, Christiane

2017-03-01

The miniaturization of semiconductors continues, importance of overlay measurement is increasing. We measured overlay with analysis SEM called Miracle Eye which can output ultrahigh acceleration voltage in 1998. Meanwhile, since 2006, we have been working on SEM based overlay measurement and developed overlay measurement function of the same layer using CD-SEM. Then, we evaluated overlay of the same layer pattern after etching. This time, in order to measure overlay after lithography, we evaluated the see-through overlay using high voltage SEM CV5000 released in October 2016. In collaboration between imec and Hitachi High-Technologies, we evaluated repeatability, TIS of SEM-OVL as well as correlation between SEM-OVL and Opt-OVL in the M1@ADI and V0@ADI process. Repeatability and TIS results are reasonable and SEM-OVL has good correlation with Opt-OVL. By overlay measurement using CV 5000, we got the following conclusions. (1)SEM_OVL results of both M1 and V0 at ADI show good correlation to OPT_OVL. (2)High voltage SEM can prove the measurement capability of a small pattern(Less than 1 2um) like device that can be placed in-die area. (3)"In-die SEM based overlay" shows possibility for high order control of scanner

Information or resolution: Which is required from an SEM to study bulk inorganic materials?: Evaluate SEMs’ practical performance

DOE PAGES

Xing, Q.

2016-07-11

Significant technological advances in scanning electron microscopy (SEM) have been achieved over the past years. Different SEMs can have significant differences in functionality and performance. This work presents the perspectives on selecting an SEM for research on bulk inorganic materials. Understanding materials demands quantitative composition and orientation information, and informative and interpretable images that reveal subtle differences in chemistry, orientation/structure, topography, and electronic structure. The capability to yield informative and interpretable images with high signal-to-noise ratios and spatial resolutions is an overall result of the SEM system as a whole, from the electron optical column to the detection system. Themore » electron optical column determines probe performance. The roles of the detection system are to capture, filter or discriminate, and convert signal electrons to imaging information. The capability to control practical operating parameters including electron probe size and current, acceleration voltage or landing voltage, working distance, detector selection, and signal filtration is inherently determined by the SEM itself. As a platform for various accessories, e.g. an energydispersive spectrometer and an electron backscatter diffraction detector, the properties of the electron optical column, specimen chamber, and stage greatly affect the performance of accessories. Ease-of-use and ease-of-maintenance are of practical importance. It is practically important to select appropriate test specimens, design suitable imaging conditions, and analyze the specimen chamber geometry and dimensions to assess the overall functionality and performance of an SEM. Finally, for an SEM that is controlled/operated with a computer, the stable software and user-friendly interface significantly affect the usability of the SEM.« less

Information or resolution: Which is required from an SEM to study bulk inorganic materials?

PubMed

Xing, Q

2016-11-01

Significant technological advances in scanning electron microscopy (SEM) have been achieved over the past years. Different SEMs can have significant differences in functionality and performance. This work presents the perspectives on selecting an SEM for research on bulk inorganic materials. Understanding materials demands quantitative composition and orientation information, and informative and interpretable images that reveal subtle differences in chemistry, orientation/structure, topography, and electronic structure. The capability to yield informative and interpretable images with high signal-to-noise ratios and spatial resolutions is an overall result of the SEM system as a whole, from the electron optical column to the detection system. The electron optical column determines probe performance. The roles of the detection system are to capture, filter or discriminate, and convert signal electrons to imaging information. The capability to control practical operating parameters including electron probe size and current, acceleration voltage or landing voltage, working distance, detector selection, and signal filtration is inherently determined by the SEM itself. As a platform for various accessories, e.g. an energy-dispersive spectrometer and an electron backscatter diffraction detector, the properties of the electron optical column, specimen chamber, and stage greatly affect the performance of accessories. Ease-of-use and ease-of-maintenance are of practical importance. It is practically important to select appropriate test specimens, design suitable imaging conditions, and analyze the specimen chamber geometry and dimensions to assess the overall functionality and performance of an SEM. For an SEM that is controlled/operated with a computer, the stable software and user-friendly interface significantly improve the usability of the SEM. SCANNING 38:864-879, 2016. © 2016 Wiley Periodicals, Inc. © Wiley Periodicals, Inc.

Information or resolution: Which is required from an SEM to study bulk inorganic materials?: Evaluate SEMs’ practical performance

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

Xing, Q.

Significant technological advances in scanning electron microscopy (SEM) have been achieved over the past years. Different SEMs can have significant differences in functionality and performance. This work presents the perspectives on selecting an SEM for research on bulk inorganic materials. Understanding materials demands quantitative composition and orientation information, and informative and interpretable images that reveal subtle differences in chemistry, orientation/structure, topography, and electronic structure. The capability to yield informative and interpretable images with high signal-to-noise ratios and spatial resolutions is an overall result of the SEM system as a whole, from the electron optical column to the detection system. Themore » electron optical column determines probe performance. The roles of the detection system are to capture, filter or discriminate, and convert signal electrons to imaging information. The capability to control practical operating parameters including electron probe size and current, acceleration voltage or landing voltage, working distance, detector selection, and signal filtration is inherently determined by the SEM itself. As a platform for various accessories, e.g. an energydispersive spectrometer and an electron backscatter diffraction detector, the properties of the electron optical column, specimen chamber, and stage greatly affect the performance of accessories. Ease-of-use and ease-of-maintenance are of practical importance. It is practically important to select appropriate test specimens, design suitable imaging conditions, and analyze the specimen chamber geometry and dimensions to assess the overall functionality and performance of an SEM. Finally, for an SEM that is controlled/operated with a computer, the stable software and user-friendly interface significantly affect the usability of the SEM.« less

Rapid degradation of phenol by ultrasound-dispersed nano-metallic particles (NMPs) in the presence of hydrogen peroxide: A possible mechanism for phenol degradation in water.

PubMed

Singh, Jiwan; Yang, Jae-Kyu; Chang, Yoon-Young

2016-06-15

The present study was carried out to investigate the degradation of phenol by ultrasonically dispersed nano-metallic particles (NMPs) in an aqueous solution of phenol. Leaching liquor from automobile shredder residue (ASR) was used to obtain the NMPs. The prepared NMPs were analyzed by scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), Fourier transform infrared spectroscopy (FTIR), and by X-ray diffraction (XRD). The SEM images show that the diameters of the NMPs were less than 50 nm. An SEM-EDX elemental analysis reveals that Fe was the most commonly found element (weight %) in the NMPs. The FTIR and XRD peaks indicate the presence of metals oxides on the surfaces of the NMPs. The results of the XPS analysis indicate that various elements (e.g., C, O, Zn, Cu, Mn, Fe) are present on the surfaces of the NMPs. The effects of the NMP dose, the initial solution pH, and of different concentrations of phenol and H2O2 on the phenol degradation characteristics were evaluated. The results of this study demonstrate that phenol degradation can be improved by increasing the amount of NMPs, whereas it is reduced with an increase in the phenol concentration. The degradation of phenol by ultrasonically dispersed NMPs followed the pseudo-first-order kinetics. The probable mechanism of phenol degradation by ultrasonically dispersed NMPs was the oxidation of phenol caused by the hydroxyl radicals produced during the reaction between H2O2 and the NMPs during the ultrasonication process. Copyright © 2016 Elsevier Ltd. All rights reserved.

Protective effect of fluoride varnish and fluoride gel on enamel erosion: roughness, SEM-EDS, and µ-EDXRF studies.

PubMed

Soares, Luís Eduardo Silva; De Carvalho Filho, Antonio Carlos Belfort

2015-03-01

The effects of fluoride treatment on bovine enamel subjected to acid erosion were studied by roughness (Ra) measurements, scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), and microenergy-dispersive X-ray fluorescence spectrometry (μ-EDXRF). Enamel samples (63) were divided into nine groups (n = 7): artificial saliva (AS), Pepsi Twist(®) (PT), orange juice (OJ), Duraphat(®)  + Pepsi Twist(®) (DPH/PT), Duraphat(®)  + orange juice (DPH/OJ), Duofluorid(®)  + Pepsi Twist(®) (DUO/PT), Duofluorid(®)  + orange juice (DUO/OJ), fluoride gel + Pepsi Twist(®) (FG/PT), and fluoride gel + orange juice (FG/OJ). Fluoride was applied and the samples were submitted to six cycles (demineralization: Pepsi Twist(®) or orange juice, 10 min; remineralization: saliva, 1 h). The enamel surface in depth was exposed and 63 line-scan maps were performed. The elemental analysis by EDS revealed that only fluoride treated groups had any detectable fluorine after erosion cycles (DPH/PT: 3.50 wt%; DPH/OJ: 3.37 wt%; DUO/PT: 2.69 wt%; DUO/OJ: 3.54 wt%; FG/PT: 2.17 wt%; FG/OJ: 2.77 wt%). PT treatment resulted in significantly higher Ra values than the artificial saliva (P < 0.001). Scanning electron microscopy (SEM) analysis of fluoride protected enamel showed areas with some globular structures or a residual layer of varnish. The enamel thickness was significantly lower in PT (0.63 ± 0.087 mm) than in DPH/PT (0.87 ± 0.16 mm) and DUO/PT (0.92 ± 0.14 mm) groups (P < 0.01). Fluoride treatments protected enamel without Ra increase and loss of enamel tissue. © 2015 Wiley Periodicals, Inc.

In vitro and in vivo evaluation of the marine sponge skeleton as a bone mimicking biomaterial.

PubMed

Nandi, Samit K; Kundu, Biswanath; Mahato, Arnab; Thakur, Narsinh L; Joardar, Siddhartha N; Mandal, Biman B

2015-02-01

This investigation was carried out to identify and characterize marine sponges as potential bioscaffolds in bone tissue engineering. The marine sponge (Biemna fortis) samples were collected from the rocky intertidal region of Anjuna, Goa, India, freeze-dried and converted to pure cristobalite at low temperature. After thorough evaluation of sponge samples by DTA-TGA thermography, XRD, FTIR, SEM and cell cytotoxicity by MTT assay, bare sponge scaffolds were fabricated by firing at 1190 °C. These scaffolds were loaded with growth factors (IGF-1 and BMP-2), checked for quasi-dynamic in vitro release kinetics and finally implanted into femoral bone defects in rabbits for up to 90 days, by keeping an empty defect as a control. The in vivo bone healing process was evaluated and compared using chronological radiology, histology, SEM and fluorochrome labeling studies. SEM revealed that the sponge skeleton possesses a collagenous fibrous network consisting of highly internetworked porosity in the size range of 10-220 μm. XRD and FTIR analysis showed a cristobalite phase with acicular crystals of high aspect ratio, and crystallinity was found to increase from 725 to 1190 °C. MTT assay demonstrated the non-cytotoxicity of the samples. A combination of burst and sustained release profile was noticed for both the growth factors and about 74.3% and 83% total release at day 28. In the radiological, histological, scanning electron microscopy and fluorochrome labeling analysis, the IGF-1 impregnated converted sponge scaffold promoted excellent osseous tissue formation followed by the BMP-2 loaded and bare one. These observations suggest that the marine sponge alone and in combination with growth factors is a promising biomaterial for bone repair and bone augmentation.

Atomic force microscopy and scanning electron microscopy analysis of daily disposable limbal ring contact lenses.

PubMed

Lorenz, Kathrine Osborn; Kakkassery, Joseph; Boree, Danielle; Pinto, David

2014-09-01

Limbal ring (also known as 'circle') contact lenses are becoming increasingly popular, especially in Asian markets because of their eye-enhancing effects. The pigment particles that give the eye-enhancing effects of these lenses can be found on the front or back surface of the contact lens or 'enclosed' within the lens matrix. The purpose of this research was to evaluate the pigment location and surface roughness of seven types of 'circle' contact lenses. Scanning electron microscopic (SEM) analysis was performed using a variable pressure Hitachi S3400N instrument to discern the placement of lens pigments. Atomic force microscopy (Dimension Icon AFM from Bruker Nano) was used to determine the surface roughness of the pigmented regions of the contact lenses. Atomic force microscopic analysis was performed in fluid phase under contact mode using a Sharp Nitride Lever probe (SNL-10) with a spring constant of 0.06 N/m. Root mean square (RMS) roughness values were analysed using a generalised linear mixed model with a log-normal distribution. Least square means and their corresponding 95% confidence intervals were estimated for each brand, location and pigment combination. SEM cross-sectional images at 500× and 2,000× magnification showed pigment on the surface of six of the seven lens types tested. The mean depth of pigment for 1-DAY ACUVUE DEFINE (1DAD) lenses was 8.1 μm below the surface of the lens, while the remaining lens types tested had pigment particles on the front or back surface. Results of the atomic force microscopic analysis indicated that 1DAD lenses had significantly lower root mean square roughness values in the pigmented area of the lens than the other lens types tested. SEM and AFM analysis revealed pigment on the surface of the lens for all types tested with the exception of 1DAD. Further research is required to determine if the difference in pigment location influences on-eye performance. © 2014 The Authors. Clinical and Experimental Optometry © 2014 Optometrists Association Australia.

Atomic force microscopy and scanning electron microscopy analysis of daily disposable limbal ring contact lenses

PubMed Central

Lorenz, Kathrine Osborn; Kakkassery, Joseph; Boree, Danielle; Pinto, David

2014-01-01

Background Limbal ring (also known as ‘circle’) contact lenses are becoming increasingly popular, especially in Asian markets because of their eye-enhancing effects. The pigment particles that give the eye-enhancing effects of these lenses can be found on the front or back surface of the contact lens or ‘enclosed’ within the lens matrix. The purpose of this research was to evaluate the pigment location and surface roughness of seven types of ‘circle’ contact lenses. Methods Scanning electron microscopic (SEM) analysis was performed using a variable pressure Hitachi S3400N instrument to discern the placement of lens pigments. Atomic force microscopy (Dimension Icon AFM from Bruker Nano) was used to determine the surface roughness of the pigmented regions of the contact lenses. Atomic force microscopic analysis was performed in fluid phase under contact mode using a Sharp Nitride Lever probe (SNL-10) with a spring constant of 0.06 N/m. Root mean square (RMS) roughness values were analysed using a generalised linear mixed model with a log-normal distribution. Least square means and their corresponding 95% confidence intervals were estimated for each brand, location and pigment combination. Results SEM cross-sectional images at 500× and 2,000× magnification showed pigment on the surface of six of the seven lens types tested. The mean depth of pigment for 1-DAY ACUVUE DEFINE (1DAD) lenses was 8.1 μm below the surface of the lens, while the remaining lens types tested had pigment particles on the front or back surface. Results of the atomic force microscopic analysis indicated that 1DAD lenses had significantly lower root mean square roughness values in the pigmented area of the lens than the other lens types tested. Conclusions SEM and AFM analysis revealed pigment on the surface of the lens for all types tested with the exception of 1DAD. Further research is required to determine if the difference in pigment location influences on-eye performance. PMID:24689948

Scanning electron microscope observation of dislocations in semiconductor and metal materials.

PubMed

Kuwano, Noriyuki; Itakura, Masaru; Nagatomo, Yoshiyuki; Tachibana, Shigeaki

2010-08-01

Scanning electron microscope (SEM) image contrasts have been investigated for dislocations in semiconductor and metal materials. It is revealed that single dislocations can be observed in a high contrast in SEM images formed by backscattered electrons (BSE) under the condition of a normal configuration of SEM. The BSE images of dislocations were compared with those of the transmission electron microscope and scanning transmission electron microscope (STEM) and the dependence of BSE image contrast on the tilting of specimen was examined to discuss the origin of image contrast. From the experimental results, it is concluded that the BSE images of single dislocations are attributed to the diffraction effect and related with high-angle dark-field images of STEM.

CdZnO coated film: A material for photovoltaic applications

NASA Astrophysics Data System (ADS)

Zargar, R. A.; Bhat, M. A.; Reshi, H. A.; Khan, S. D.

2018-06-01

The present study reports structural and optical parameters of wide band gap oxide thick film prepared by screen-printing followed by sintering route. Characterization of the samples was carried out with UV-spectroscopy, XRD, SEM, and Photoluminous study. The XRD and SEM studies reveal that the film deposited is polycrystalline, double phase, and porous with unsymmetrical grain distributions. Optical diffused reflection spectroscopy and Pl measurements give optical band gap of 2.87 eV and near band edge emission at 430 nm.

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.

Electrical and magnetic properties of spherical SmFeO{sub 3} synthesized by aspartic acid assisted combustion method

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

Yuvaraj, Subramanian; Layek, Samar; Vidyavathy, S. Manisha

2015-12-15

Highlights: • SmFeO{sub 3} is synthesized by simple combustion method using aspartic acid as the fuel. • The particles are spherical in shape with the size ranges between 150 and 300 nm. • Cole–Cole plot infers the bulk conduction mechanism. • Room temperature VSM analysis reveal the weak ferromagnetic behaviour of SmFeO{sub 3}. • Mössbauer analysis elucidates the +3 oxidation state of Fe atoms. - Abstract: Samarium orthoferrite (SmFeO{sub 3}) is synthesized by a simple combustion method using aspartic acid as fuel. Phase purity and functional groups are analyzed via X-ray diffraction (XRD) and Fourier transform infrared (FT-IR) analysis, whichmore » confirms the single phase formation of orthorhombic SmFeO{sub 3}. Approximately spherical particles with size range 150–300 nm is revealed by scanning electron microscope (SEM). The conductivity of the material is identified by the single semicircle obtained in the solid state impedance spectra at elevated temperatures. The calculated electrical conductivity increases with increasing temperature, inferring the semiconducting nature of SmFeO{sub 3}. A magnetic study at room temperature revealed weak ferromagnetic behaviour in SmFeO{sub 3} due to Dzyaloshinsky–Moriya antisymmetric exchange interaction mechanism. Mössbauer analysis confirmed the +3 oxidation state of iron and magnetic ordering of the sample at room temperature.« less

Provenance and depositional environment of epi-shelf lake sediment from Schirmacher Oasis, East Antarctica, vis-à-vis scanning electron microscopy of quartz grain, size distribution and chemical parameters

NASA Astrophysics Data System (ADS)

Shrivastava, Prakash K.; Asthana, Rajesh; Roy, Sandip K.; Swain, Ashit K.; Dharwadkar, Amit

2012-07-01

The scientific study of quartz grains is a powerful tool in deciphering the depositional environment and mode of transportation of sediments, and ultimately the origin and classification of sediments. Surface microfeatures, angularity, chemical features, and grain-size analysis of quartz grains, collectively reveal the sedimentary and physicochemical processes that acted on the grains during different stages of their geological history. Here, we apply scanning electron microscopic (SEM) analysis to evaluating the sedimentary provenance, modes of transport, weathering characteristics, alteration, and sedimentary environment of selected detrital quartz grains from the peripheral part of two epi-shelf lakes (ESL-1 and ESL-2) of the Schirmacher Oasis of East Antarctica. Our study reveals that different styles of physical weathering, erosive signatures, and chemical precipitation variably affected these quartz grains before final deposition as lake sediments. Statistical analysis (central tendencies, sorting, skewness, and kurtosis) indicates that these quartz-bearing sediments are poorly sorted glaciofluvial sediments. Saltation and suspension seem to have been the two dominant modes of transportation, and chemical analysis of these sediments indicates a gneissic provenance.

Pb(II) adsorption by biomass from chemically modified aquatic macrophytes, Salvinia sp. and Pistia stratiotes.

PubMed

de Moraes Ferreira, Rachel; de Souza, Michael Douglas Peçanha; Takase, Iracema; de Araujo Stapelfeldt, Danielle Marques

2016-01-01

This study used two biosorbents obtained from the aquatic plants Salvinia sp. and Pistia stratiotes to establish a sustainable and alternative treatment for industrial wastewater and other water bodies that contain Pb(II). The biosorbent named Salvinia with NaOH (SOH) was obtained from Salvinia sp., and Salvinia and Pistia mixture with NaOH (SPOH) was obtained from a mixture of the two plants in a 1:1 ratio. The biosorbents were characterized by zeta potential, infrared (IR) spectroscopy, scanning electron microscopy (SEM), energy-dispersive spectroscopy and Boehm titration. The results of Boehm titration and IR analysis indicated the presence of basic functional groups, whereas those of SEM analysis indicated that the biosorbents have a structure conducive to adsorption. Batch adsorption experiments were performed to observe the effects of pH, contact time, initial lead concentration and temperature on the metal removal process. The results revealed that the biosorbents efficiently removed Pb(II) from aqueous solutions, with a maximum observed adsorption capacity (saturation limits, qmax) of 202 mg g(-1) and 210.1 mg g(-1) for SPOH and SOH, respectively. The Freundlich, Langmuir and Dubinin-Radushkevich models were applied to the data; these biosorbent studies did not satisfactorily adjust to either of the models, but the information obtained helped us understand the adsorption mechanism.

Inhibition of early biofilm formation by glass-ionomer incorporated with chlorhexidine in vivo: a pilot study.

PubMed

Du, X; Huang, X; Huang, C; Frencken, J E; Yang, T

2012-03-01

This pilot study investigated the antibiofilm effects of glass-ionomer cements (GICs) and resin-modified glass-ionomer cements (RMGICs) incorporated with chlorhexidine (CHX) in vivo. Experimental GICs and RMGICs containing 2% CHX were obtained by mixing CHX with the powder of GICs (CHXGIC) and RMGICs (CHXRMGIC). Four groups of specimens were prepared in a standardized size. After polishing and sterilization, they were bonded to the buccal surface of the molars in the first and second quadrant of volunteers and left untouched for 4 hours and 24 hours, respectively. The bacterial vitality of plaque was then analysed by confocal laser scanning microscopy (CLSM). The bacterial morphology and biofilm accumulation were determined by scanning electron microscopy (SEM). The pH value of biofilm was assessed by Plaque Indicator Kits. CLSM analysis revealed that bacterial vitality of the biofilm on CHXGIC and CHXRMGIC was significantly lower than that on GIC and RMGIC. SEM analysis indicated that the morphology of bacteria on CHXGIC and CHXRMGIC was irregular. The pH value of biofilm on the experimental materials presented no statistically significant difference. Twenty-four hour bacterial vitality on GICs and RMGICs with CHX are lower in micro-organisms than on conventional GICs and RMGICs. © 2012 Australian Dental Association.

The relationship between perceived discrimination and psychological distress among Chinese pulmonary tuberculosis patients: the moderating role of self-esteem.

PubMed

Feng, Danjun; Xu, Lingzhong

2015-01-01

This study described the prevalence of psychological distress and examined the moderating effect of self-esteem in the relationship between perceived discrimination and psychological distress among Chinese pulmonary tuberculosis (TB) patients. Seven hundred and twenty patients with TB from three cities of Shandong Province in eastern China participated in a cross-sectional survey. Patients were measured with the Kessler 10 (K10), the Rosenberg self-esteem scale, and a self-developed perceived discrimination questionnaire. A total of 58.6% of patients with TB scored above 16 on the K10, indicating moderate and serious psychological distress. Chi-square test revealed that female patients reported higher psychological distress than male patients. The structural equation modeling (SEM) analysis among the whole sample indicated that perceived discrimination was significantly related with psychological distress (β = .28, p ≤ .01). The multiple group analysis of SEM showed that perceived discrimination had a significantly substantial (β = .50, p ≤ .001), significantly moderate (β = .15, p ≤ .01), and insignificant effect (β = .05, p ≥ .05) on psychological distress among low self-esteem, moderate self-esteem, and high self-esteem patients with TB, respectively, which verified the moderating effect of self-esteem in the relationship between perceived discrimination and psychological distress.

Comparative Biomechanical and Microstructural Analysis of Native versus Peracetic Acid-Ethanol Treated Cancellous Bone Graft

PubMed Central

Rauh, Juliane; Despang, Florian; Baas, Jorgen; Liebers, Cornelia; Pruss, Axel; Günther, Klaus-Peter; Stiehler, Maik

2014-01-01

Bone transplantation is frequently used for the treatment of large osseous defects. The availability of autologous bone grafts as the current biological gold standard is limited and there is a risk of donor site morbidity. Allogenic bone grafts are an appealing alternative, but disinfection should be considered to reduce transmission of infection disorders. Peracetic acid-ethanol (PE) treatment has been proven reliable and effective for disinfection of human bone allografts. The purpose of this study was to evaluate the effects of PE treatment on the biomechanical properties and microstructure of cancellous bone grafts (CBG). Forty-eight human CBG cylinders were either treated by PE or frozen at −20°C and subjected to compression testing and histological and scanning electron microscopy (SEM) analysis. The levels of compressive strength, stiffness (Young's modulus), and fracture energy were significantly decreased upon PE treatment by 54%, 59%, and 36%, respectively. Furthermore, PE-treated CBG demonstrated a 42% increase in ultimate strain. SEM revealed a modified microstructure of CBG with an exposed collagen fiber network after PE treatment. We conclude that the observed reduced compressive strength and reduced stiffness may be beneficial during tissue remodeling thereby explaining the excellent clinical performance of PE-treated CBG. PMID:24678514

Effect of molarity on sol-gel routed nano TiO2 thin films

NASA Astrophysics Data System (ADS)

Lourduraj, Stephen; Williams, Rayar Victor

The nanostructured titanium dioxide (TiO2) thin films have been prepared for the molar concentrations of titanium tetra isopropoxide (TTIP) 0.05M, 0.1M, 0.15M and 0.2M by sol-gel routed spin coating technique with calcination at 450∘C. The processing parameters such as, pH value (8), catalyst HCl (0.1ml), spin speed (3000rpm) and calcination temperature (450∘C) are optimized. The crystalline nature and surface morphology were analyzed by XRD, SEM and AFM analysis. The XRD results confirm that the films are crystalline with anatase phase, and are nanostructured. The SEM micrographs of the TiO2 film reveal the spherical nature of the particle. AFM analysis establishes that the uniformity of the TiO2 thin film was optimized at 0.2M. The optical measurements show that the transmittance depends on the molarity, and the optical band gap energy of TiO2 films is found to be inversely proportional to molarity. The I-V characteristics exhibit that the molarity strongly influences the electrical conductivity of the film. The results indicate that the significant effect of molarity on structural, optical and electrical properties of the nanostructured TiO2 thin films will be useful to photovoltaic application.

Surface characteristic of chemically converted graphene coated low carbon steel by electro spray coating method for polymer electrolyte membrane fuel cell bipolar plate.

PubMed

Kim, Jungsoo; Kim, Yang Do; Nam, Dae Geun

2013-05-01

Graphene was coated on low carbon steel (SS400) by electro spray coating method to improve its properties of corrosion resistance and contact resistance. Exfoliated graphite was made of the graphite by chemical treatment (Chemically Converted Graphene, CCG). CCG is distributed using dispersing agent, and low carbon steel was coated with diffuse graphene solution by electro spray coating method. The structure of the CCG was analyzed using XRD and the coating layer of surface was analyzed using SEM. Analysis showed that multi-layered graphite structure was destroyed and it was transformed in to fine layers graphene structure. And the result of SEM analysis on the surface and the cross section, graphene layer was uniformly formed with 3-5 microm thickness on the surface of substrate. Corrosion resistance test was applied in the corrosive solution which is similar to the polymer electrolyte membrane fuel cell (PEMFC) stack inside. And interfacial contact resistance (ICR) test was measured to simulate the internal operating conditions of PEMFC stack. As a result of measuring corrosion resistance and contact resistance, it could be confirmed that low carbon steel coated with CCG was revealed to be more effective in terms of its applicability as PEMFC bipolar plate.

Plackett-Burman experimental design for bacterial cellulose-silica composites synthesis.

PubMed

Guzun, Anicuta Stoica; Stroescu, Marta; Jinga, Sorin Ion; Voicu, Georgeta; Grumezescu, Alexandru Mihai; Holban, Alina Maria

2014-09-01

Bacterial cellulose-silica hybrid composites were prepared starting from wet bacterial cellulose (BC) membranes using Stöber reaction. The structure and surface morphology of hybrid composites were examined by FTIR and SEM. The SEM pictures revealed that the silica particles are attached to BC fibrils and are well dispersed in the BC matrix. The influence of silica particles upon BC crystallinity was studied using XRD analysis. Thermogravimetric (TG) analysis showed that the composites are stable up to 300°C. A Plackett-Burman design was applied in order to investigate the influence of process parameters upon silica particle sizes and silica content of BC-silica composites. The statistical model predicted that it is possible for silica particles size to vary the synthesis parameters in order to obtain silica particles deposed on BC membranes in the range from 34.5 to 500 nm, the significant parameters being ammonia concentration, reaction time and temperature. The silica content also varies depending on process parameters, the statistical model predicting that the most influential parameters are water-tetraethoxysilane (TEOS) ratio and reaction temperature. The antimicrobial behavior on Staphylococcus aureus of BC-silica composites functionalized with usnic acid (UA) was also studied, in order to create improved surfaces with antiadherence and anti-biofilm properties. Copyright © 2014 Elsevier B.V. All rights reserved.

Improving anti-felting characteristics of Merino wool fiber by 2.5 MHz atmosphere pressure air plasma

NASA Astrophysics Data System (ADS)

Chandwani, Nisha; Dave, Purvi; Jain, Vishal; Nema, Sudhir; Mukherjee, Subroto

2017-04-01

The present work investigates the effect of high frequency (2.5 MHz) Dielectric Barrier Discharge (DBD) in air on surface characteristics of Merino wool as a function of plasma exposure time (5s to 15s). The FE-SEM (Field Emission Scanning Electron Microscopy), EDS (Energy Dispersive X-ray spectrum) and Derivative ATR-FTIR (Attenuated Total Reflection- Fourier Transform Infrared) Spectroscopy are used to study physio-chemical changes induced by plasma. These physio-chemical properties of fibers can be co-related with the felting behaviour of the wool fiber, which leads to shrinkage and pilling of garments while laundering. Felting occurs mainly because of presence of outermost hydrophobic cuticle layer having sharp scales. The FE-SEM analysis of wool fiber surface reveals that cuticle scales on wool fiber become blunt after plasma processing. The ATR-FTIR analysis along with second order derivative spectroscopy demonstrates the cleavage of di-sulphide bonds of cuticle and formation of sulphur-oxygen groups such as Cystine Sulphonate (-S-SO3-), cysteic acid (-SO3-), cystine monoxide(-SO-S-), cysteine di-oxide (-SO2-S-). A possible explanation about how the combined effect of morphological and chemical changes induced by plasma results in minimizing the felting of wool fibers is discussed.

Synthesis of Galaxite, Mn0.9Co0.1Al2O4, and its application as a novel nanocatalyst for electrochemical hydrogen evolution reaction

NASA Astrophysics Data System (ADS)

Saeidfirozeh, Homa; Shafiekhani, Azizollah; Beheshti-Marnani, Amirkhosro; Askari, Mohammad Bagher

2018-06-01

A new compound Mn0.9Co0.1Al2O4 nanowires were synthesized by thermal method. The resulting powder samples were characterized by scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDX), and X-ray diffraction (XRD). We found that a set of phase transformation occurred during the process. Eventually, five phases including three spinal phases, the corundum (á-Al2O3) and MnO were formed at 1100 °C.As dominant morphology, the cubic galaxite nanowires were identified by X-ray analysis. Moreover, X-ray analysis showed that Mn3O4 and Co3O4 nanoparticles were formed in tetragonal and cubic symmetry respectively. The SEM image revealed that a dominate morphology of product has cubic nanowires shape with an average diameter in range 38-43 nm. Furthermore, we observed that influence of temperature was very important in the nanowire formation process. Electrochemical hydrogen evolution reaction (HER) of synthetic composite was evaluated and the over potential of HER was calculated about 110 mV with low Tafel slope equal to 42 mV dec-1, which was comparable with amounts reported transition metal dichalcogenides with satisfying durability.

The risk assessment of heavy metals in Futian mangrove forest sediment in Shenzhen Bay (South China) based on SEM-AVS analysis.

PubMed

Chai, Minwei; Shen, Xiaoxue; Li, Ruili; Qiu, Guoyu

2015-08-15

The risks of heavy metal in Futian mangrove forest sediment were assessed using the acid-volatile sulfide (AVS) and simultaneously extracted metals (SEM) methods. The results indicated that AVS distributions were more variable than the SEM distributions at all 16 sampling sites. The positive correlation between AVS and SEM indicated that their similar formative and existing conditions and that AVS acted as an important carrier for SEM. The major SEM component was Zn (69.7.3-94.2%), whereas the Cd contribution (the most toxic metal present) to SEM was no more than 1%. The possible adverse effects caused by heavy metals at ten sampling sites may be due to higher levels of SEMs, rather than AVSs. The total organic carbon (TOC) was an important metal-binding phase in the sediments. Taking into account the TOC concentration, there were no adverse effects due to heavy metals in any of the Futian mangrove forest sediments. Copyright © 2015 Elsevier Ltd. All rights reserved.

Standard deviation and standard error of the mean.

PubMed

Lee, Dong Kyu; In, Junyong; Lee, Sangseok

2015-06-01

In most clinical and experimental studies, the standard deviation (SD) and the estimated standard error of the mean (SEM) are used to present the characteristics of sample data and to explain statistical analysis results. However, some authors occasionally muddle the distinctive usage between the SD and SEM in medical literature. Because the process of calculating the SD and SEM includes different statistical inferences, each of them has its own meaning. SD is the dispersion of data in a normal distribution. In other words, SD indicates how accurately the mean represents sample data. However the meaning of SEM includes statistical inference based on the sampling distribution. SEM is the SD of the theoretical distribution of the sample means (the sampling distribution). While either SD or SEM can be applied to describe data and statistical results, one should be aware of reasonable methods with which to use SD and SEM. We aim to elucidate the distinctions between SD and SEM and to provide proper usage guidelines for both, which summarize data and describe statistical results.

Standard deviation and standard error of the mean

PubMed Central

In, Junyong; Lee, Sangseok

2015-01-01

In most clinical and experimental studies, the standard deviation (SD) and the estimated standard error of the mean (SEM) are used to present the characteristics of sample data and to explain statistical analysis results. However, some authors occasionally muddle the distinctive usage between the SD and SEM in medical literature. Because the process of calculating the SD and SEM includes different statistical inferences, each of them has its own meaning. SD is the dispersion of data in a normal distribution. In other words, SD indicates how accurately the mean represents sample data. However the meaning of SEM includes statistical inference based on the sampling distribution. SEM is the SD of the theoretical distribution of the sample means (the sampling distribution). While either SD or SEM can be applied to describe data and statistical results, one should be aware of reasonable methods with which to use SD and SEM. We aim to elucidate the distinctions between SD and SEM and to provide proper usage guidelines for both, which summarize data and describe statistical results. PMID:26045923

A brief discussion about image quality and SEM methods for quantitative fractography of polymer composites.

PubMed

Hein, L R O; Campos, K A; Caltabiano, P C R O; Kostov, K G

2013-01-01

The methodology for fracture analysis of polymeric composites with scanning electron microscopes (SEM) is still under discussion. Many authors prefer to use sputter coating with a conductive material instead of applying low-voltage (LV) or variable-pressure (VP) methods, which preserves the original surfaces. The present work examines the effects of sputter coating with 25 nm of gold on the topography of carbon-epoxy composites fracture surfaces, using an atomic force microscope. Also, the influence of SEM imaging parameters on fractal measurements is evaluated for the VP-SEM and LV-SEM methods. It was observed that topographic measurements were not significantly affected by the gold coating at tested scale. Moreover, changes on SEM setup leads to nonlinear outcome on texture parameters, such as fractal dimension and entropy values. For VP-SEM or LV-SEM, fractal dimension and entropy values did not present any evident relation with image quality parameters, but the resolution must be optimized with imaging setup, accompanied by charge neutralization. © Wiley Periodicals, Inc.

A simple method for detection of gunshot residue particles from hands, hair, face, and clothing using scanning electron microscopy/wavelength dispersive X-ray (SEM/WDX).

PubMed

Kage, S; Kudo, K; Kaizoji, A; Ryumoto, J; Ikeda, H; Ikeda, N

2001-07-01

We devised a simple and rapid method for detection of gunshot residue (GSR) particles, using scanning electron microscopy/wavelength dispersive X-ray (SEM/WDX) analysis. Experiments were done on samples containing GSR particles obtained from hands, hair, face, and clothing, using double-sided adhesive coated aluminum stubs (tape-lift method). SEM/WDX analyses for GSR were carried out in three steps: the first step was map analysis for barium (Ba) to search for GSR particles from lead styphnate primed ammunition, or tin (Sn) to search for GSR particles from mercury fulminate primed ammunition. The second step was determination of the location of GSR particles by X-ray imaging of Ba or Sn at a magnification of x 1000-2000 in the SEM, using data of map analysis, and the third step was identification of GSR particles, using WDX spectrometers. Analysis of samples from each primer of a stub took about 3 h. Practical applications were shown for utility of this method.

The development of comparative bias index

NASA Astrophysics Data System (ADS)

Aimran, Ahmad Nazim; Ahmad, Sabri; Afthanorhan, Asyraf; Awang, Zainudin

2017-08-01

Structural Equation Modeling (SEM) is a second generation statistical analysis techniques developed for analyzing the inter-relationships among multiple variables in a model simultaneously. There are two most common used methods in SEM namely Covariance-Based Structural Equation Modeling (CB-SEM) and Partial Least Square Path Modeling (PLS-PM). There have been continuous debates among researchers in the use of PLS-PM over CB-SEM. While there is few studies were conducted to test the performance of CB-SEM and PLS-PM bias in estimating simulation data. This study intends to patch this problem by a) developing the Comparative Bias Index and b) testing the performance of CB-SEM and PLS-PM using developed index. Based on balanced experimental design, two multivariate normal simulation data with of distinct specifications of size 50, 100, 200 and 500 are generated and analyzed using CB-SEM and PLS-PM.

Flexible regenerated cellulose/polypyrrole composite films with enhanced dielectric properties.

PubMed

Raghunathan, Sreejesh Poikavila; Narayanan, Sona; Poulose, Aby Cheruvathur; Joseph, Rani

2017-02-10

Flexible regenerated cellulose/polypyrrole (RC-PPy) conductive composite films were prepared by insitu polymerization of pyrrole on regenerated cellulose (RC) matrix using ammonium persulphate as oxidant. FTIR, XPS and XRD analysis of RC-PPy composite films revealed strong interaction between polypyrrole (PPy) and RC matrix. XRD results indicated that crystalline structure of RC matrix remains intact even after composite formation. SEM micrographs revealed the formation of a continuous conductive network of PPy particles in the RC matrix, leading to significant improvement in electrical and dielectric properties. The electrical conductivity of RC-PPy composites with 12wt% of PPy was 3.2×10 -5 S/cm, which is approximately seven fold higher than that of RC. Composites showed high dielectric constant and low dielectric loss values, which is essential in capacitor application. Copyright © 2016 Elsevier Ltd. All rights reserved.

Surface Characteristics and Catalytic Activity of Copper Deposited Porous Silicon Powder

PubMed Central

Abdul Halim, Muhammad Yusri; Tan, Wei Leng; Abu Bakar, Noor Hana Hanif; Abu Bakar, Mohamad

2014-01-01

Porous structured silicon or porous silicon (PS) powder was prepared by chemical etching of silicon powder in an etchant solution of HF: HNO3: H2O (1:3:5 v/v). An immersion time of 4 min was sufficient for depositing Cu metal from an aqueous solution of CuSO4 in the presence of HF. Scanning electron microscopy (SEM) analysis revealed that the Cu particles aggregated upon an increase in metal content from 3.3 wt% to 9.8 wt%. H2-temperature programmed reduction (H2-TPR) profiles reveal that re-oxidation of the Cu particles occurs after deposition. Furthermore, the profiles denote the existence of various sizes of Cu metal on the PS. The Cu-PS powders show excellent catalytic reduction on the p-nitrophenol regardless of the Cu loadings. PMID:28788272

Type 1 diabetes mellitus effects on dental enamel formation revealed by microscopy and microanalysis.

PubMed

Silva, Bruna Larissa Lago; Medeiros, Danila Lima; Soares, Ana Prates; Line, Sérgio Roberto Peres; Pinto, Maria das Graças Farias; Soares, Telma de Jesus; do Espírito Santo, Alexandre Ribeiro

2018-03-01

Type 1 diabetes mellitus (T1DM) largely affects children, occurring therefore at the same period of deciduous and permanent teeth development. The aim of this work was to investigate birefringence and morphology of the secretory stage enamel organic extracellular matrix (EOECM), and structural and mechanical features of mature enamel from T1DM rats. Adult Wistar rats were maintained alive for a period of 56 days after the induction of experimental T1DM with a single dose of streptozotocin (60 mg/kg). After proper euthanasia of the animals, fixed upper incisors were accurately processed, and secretory stage EOECM and mature enamel were analyzed by transmitted polarizing and bright field light microscopies (TPLM and BFLM), energy-dispersive x-ray (EDX) analysis, scanning electron microscopy (SEM), and microhardness testing. Bright field light microscopies and transmitted polarizing light microscopies showed slight morphological changes in the secretory stage EOECM from diabetic rats, which also did not exhibit statistically significant alterations in birefringence brightness when compared to control animals (P > .05). EDX analysis showed that T1DM induced statistically significant little increases in the amount of calcium and phosphorus in outer mature enamel (P < .01) with preservation of calcium/phosphorus ratio in that structure (P > .05). T1DM also caused important ultrastructural alterations in mature enamel as revealed by SEM and induced a statistically significant reduction of about 13.67% in its microhardness at 80 μm from dentin-enamel junction (P < .01). This study shows that T1DM may disturb enamel development, leading to alterations in mature enamel ultrastructure and in its mechanical features. © 2017 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

Effect of autoclaving on the surfaces of TiN -coated and conventional nickel-titanium rotary instruments.

PubMed

Spagnuolo, G; Ametrano, G; D'Antò, V; Rengo, C; Simeone, M; Riccitiello, F; Amato, M

2012-12-01

To evaluate the effects of repeated autoclave sterilization cycles on surface topography of conventional nickel-titanium ( NiTi ) and titanium nitride ( TiN )-coated rotary instruments. A total of 60 NiTi rotary instruments, 30 ProTaper (Dentsply Maillefer) and 30 TiN -coated AlphaKite (Komet/Gebr. Brasseler), were analysed. Instruments were evaluated in the as-received condition and after 1, 5 and 10 sterilization cycles. After sterilization, the samples were observed using scanning electron microscope (SEM), and surface chemical analysis was performed on each instrument with energy dispersive X-ray spectroscopy (EDS). Moreover, the samples were analysed by atomic force microscopy (AFM), and roughness average (Ra) and the root mean square value (RMS) of the scanned surface profiles were recorded. Data were analysed by means of anova followed by Tukey's test. Scanning electron microscope observations revealed the presence of pitting and deep milling marks in all instruments. EDS analysis confirmed that both types of instruments were composed mainly of nickel and titanium, whilst AlphaKite had additional nitride. After multiple autoclave sterilization cycles, SEM examinations revealed an increase in surface alterations, and EDS values indicated changes in chemical surface composition in all instruments. Ra and RMS values of ProTaper significantly increased after 5 (P = 0.006) and 10 cycles (P = 0.002) with respect to the as-received instruments, whilst AlphaKite showed significant differences compared with the controls after 10 cycles (P = 0.03). Multiple autoclave sterilization cycles modified the surface topography and chemical composition of conventional and TiN -coated NiTi rotary instruments. © 2012 International Endodontic Journal.

Hybrid Aorta Constructs via In Situ Crosslinking of Poly(glycerol-sebacate) Elastomer Within a Decellularized Matrix.

PubMed

Guler, Selcan; Hosseinian, Pezhman; Aydin, Halil Murat

2017-01-01

Decellularization of tissues and organs has high potential to obtain unique conformation and composition as native tissue structure but may result in weakened tissue mechanical strength. In this study, poly(glycerol-sebacate) (PGS) elastomers were combined with decellularized aorta fragments to investigate the changes in mechanical properties. PGS prepolymer was synthesized via microwave irradiation and then in situ crosslinked within the decellularized aorta extracellular matrix (ECM). Tensile strength (σ) values were found comparable as 0.44 ± 0.10 MPa and 0.57 ± 0.18 MPa for native and hybrid aorta samples, respectively, while elongation at break (ɛ) values were 261% ± 17%, 7.5% ± 0.57%, and 22.18% ± 2.48% for wet control (native), decellularized dried aortae, and hybrid matrices, showing elastic contribution. Young's modulus data indicate that there was a threefold decrease in stiffness compared to decellularized samples once PGS is introduced into the ECM structure. Scanning electron microscopy (SEM) analysis of hybrid grafts revealed that the construct preserves porosity in medial layer of the vessel. Biocompatibility analyses showed no cytotoxic effects on human abdominal aorta smooth muscle cells. Cell studies showed 98% activity in hybrid graft extracts. As a control, collagen coating of the hybrid grafts was performed in the recellularization stage. SEM analysis of recellularized hybrid grafts revealed that cells were attached to the surface of the hybrid graft and proliferated during the 14 days of culture in both groups. This study shows that introducing an elastomer into the native ECM structure following decellularization process can be a useful approach for the preparation of mechanically enhanced composites for soft tissues.

Subgrain boundary analyses in deformed orthopyroxene by TEM/STEM with EBSD-FIB sample preparation technique

NASA Astrophysics Data System (ADS)

Kogure, Toshihiro; Raimbourg, Hugues; Kumamoto, Akihito; Fujii, Eiko; Ikuhara, Yuichi

2014-12-01

High-resolution structure analyses using electron beam techniques have been performed for the investigation of subgrain boundaries (SGBs) in deformed orthopyroxene (Opx) in mylonite from Hidaka Metamorphic Belt, Hokkaido, Japan, to understand ductile deformation mechanism of silicate minerals in shear zones. Scanning electron microscopy (SEM) and electron backscatter diffraction (EBSD) analysis of Opx porphyroclasts in the mylonitic rock indicated that the crystal orientation inside the Opx crystals gradually changes by rotation about the b-axis by SGBs and crystal folding. In order to observe the SGBs along the b-axis by transmission electron microscopy (TEM) or scanning TEM (STEM), the following sample preparation protocol was adopted. First, petrographic thin sections were slightly etched with hydrofluoric acid to identify SGBs in SEM. The Opx crystals whose b-axes were oriented close to the normal of the surface were identified by EBSD, and the areas containing SGBs were picked and thinned for (S) TEM analysis with a focused ion beam instrument with micro-sampling system. High-resolution TEM imaging of the SGBs in Opx revealed various boundary structures from a periodic array of dissociated (100) [001] edge dislocations to partially or completely incoherent crystals, depending on the misorientation angle. Atomic-resolution STEM imaging clearly confirmed the formation of clinopyroxene (Cpx) structure between the dissociated partial dislocations. Moreover, X-ray microanalysis in STEM revealed that the Cpx contains a considerable amount of calcium replacing iron. Such chemical inhomogeneity may limit glide motion of the dislocation and eventually the plastic deformation of the Opx porphyroclasts at a low temperature. Chemical profiles across the high-angle incoherent SGB also showed an enrichment of the latter in calcium at the boundary, suggesting that SGBs are an efficient diffusion pathway of calcium out of host Opx grain during cooling.

Nanohybrid vs. fine hybrid composite in Class II cavities: clinical results and margin analysis after four years.

PubMed

Krämer, Norbert; Reinelt, Christian; Richter, Gert; Petschelt, Anselm; Frankenberger, Roland

2009-06-01

This controlled prospective split-mouth study evaluated the clinical behavior of two different resin composites in extended Class II cavities over a period of four years. Thirty patients received 68 direct resin composite restorations (Grandio bonded with Solobond M: n=36, Tetric Ceram bonded with Syntac: n=32) by one dentist in a private practice. All restorations were replacement fillings, 24 cavities (35%) revealed no enamel at the bottom of the proximal box, in 33 cavities (48%) the proximal enamel width was less than 0.5mm. The restorations were examined according to modified USPHS criteria at baseline, and after six months, one, two, and four years. At each recall, impressions were taken for replica preparation. Replicas of 44 select subjects were assessed for marginal quality under a stereo light microscope (SLM) at 130x and 22 replicas were assessed under a scanning electron microscope (SEM) at 200x. Both recall rate and survival rate were 100% after four years of clinical service. No significant difference was found between the restorative materials (p>0.05; Mann-Whitney U-test). Hypersensitivities were significantly reduced over time (p<0.05; Friedman test). A significant deterioration over time was found for the criteria marginal integrity (66% bravo after four years), tooth integrity (15% bravo), filling integrity (73% bravo) and proximal contact (p<0.05; Friedman test). SLM and SEM analysis of restoration margins revealed differences in the amount of perfect margins, in favor of Tetric Ceram (p<0.05). Both materials performed satisfactorily over the four-year observation period. Due to the extension of the restorations, wear was clearly visible after four years of clinical service with 50% bravo ratings.

A fractographic study of clinically retrieved zirconia-ceramic and metal-ceramic fixed dental prostheses.

PubMed

Pang, Zhen; Chughtai, Asima; Sailer, Irena; Zhang, Yu

2015-10-01

A recent 3-year randomized controlled trial (RCT) of tooth supported three- to five-unit zirconia-ceramic and metal-ceramic posterior fixed dental prostheses (FDPs) revealed that veneer chipping and fracture in zirconia-ceramic systems occurred more frequently than those in metal-ceramic systems [1]. This study seeks to elucidate the underlying mechanisms responsible for the fracture phenomena observed in this RCT using a descriptive fractographic analysis. Vinyl-polysiloxane impressions of 12 zirconia-ceramic and 6 metal-ceramic FDPs with veneer fractures were taken from the patients at the end of a mean observation of 40.3±2.8 months. Epoxy replicas were produced from these impressions [1]. All replicas were gold coated, and inspected under the optical microscope and scanning electron microscope (SEM) for descriptive fractography. Among the 12 zirconia-ceramic FDPs, 2 had small chippings, 9 had large chippings, and 1 exhibited delamination. Out of 6 metal-ceramic FDPs, 5 had small chippings and 1 had large chipping. Descriptive fractographic analysis based on SEM observations revealed that fracture initiated from the wear facet at the occlusal surface in all cases, irrespective of the type of restoration. Zirconia-ceramic and metal-ceramic FDPs all fractured from microcracks that emanated from occlusal wear facets. The relatively low fracture toughness and high residual tensile stress in porcelain veneer of zirconia restorations may contribute to the higher chipping rate and larger chip size in zirconia-ceramic FDPs relative to their metal-ceramic counterparts. The low veneer/core interfacial fracture energy of porcelain-veneered zirconia may result in the occurrence of delamination in zirconia-ceramic FDPs. Copyright © 2015 Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved.

A fractographic study of clinically retrieved zirconia–ceramic and metal–ceramic fixed dental prostheses

PubMed Central

Pang, Zhen; Chughtai, Asima; Sailer, Irena; Zhang, Yu

2015-01-01

Objectives A recent 3-year randomized controlled trial (RCT) of tooth supported three- to five-unit zirconia–ceramic and metal–ceramic posterior fixed dental prostheses (FDPs) revealed that veneer chipping and fracture in zirconia–ceramic systems occurred more frequently than those in metal–ceramic systems [1]. This study seeks to elucidate the underlying mechanisms responsible for the fracture phenomena observed in this RCT using a descriptive fractographic analysis. Methods Vinyl-polysiloxane impressions of 12 zirconia–ceramic and 6 metal–ceramic FDPs with veneer fractures were taken from the patients at the end of a mean observation of 40.3 ± 2.8 months. Epoxy replicas were produced from these impressions [1]. All replicas were gold coated, and inspected under the optical microscope and scanning electron microscope (SEM) for descriptive fractography. Results Among the 12 zirconia–ceramic FDPs, 2 had small chippings, 9 had large chippings, and 1 exhibited delamination. Out of 6 metal–ceramic FDPs, 5 had small chippings and 1 had large chipping. Descriptive fractographic analysis based on SEM observations revealed that fracture initiated from the wear facet at the occlusal surface in all cases, irrespective of the type of restoration. Significance Zirconia–ceramic and metal–ceramic FDPs all fractured from microcracks that emanated from occlusal wear facets. The relatively low fracture toughness and high residual tensile stress in porcelain veneer of zirconia restorations may contribute to the higher chipping rate and larger chip size in zirconia–ceramic FDPs relative to their metal–ceramic counterparts. The low veneer/core interfacial fracture energy of porcelain-veneered zirconia may result in the occurrence of delamination in zirconia–ceramic FDPs. PMID:26233469

Reliability of intestinal temperature using an ingestible telemetry pill system during exercise in a hot environment.

PubMed

Ruddock, Alan D; Tew, Garry A; Purvis, Alison J

2014-03-01

Ingestible telemetry pill systems are being increasingly used to assess the intestinal temperature during exercise in hot environments. The purpose of this investigation was to assess the interday reliability of intestinal temperature during an exercise-heat challenge. Intestinal temperature was recorded as 12 physically active men (25 ± 4 years, stature 181.7 ± 7.0 cm, body mass 81.1 ± 10.6 kg) performed two 60-minute bouts of recumbent cycling (50% of peak aerobic power [watts]) in an environmental chamber set at 35° C 50% relative humidity 3-10 days apart. A range of statistics were used to calculate the reliability, including a paired t-test, 95% limits of agreement (LOA), coefficient of variation (CV), standard error of measurement (SEM), Pearson's correlation coefficient (r), intraclass correlation coefficient (ICC), and Cohen's d. Statistical significance was set at p ≤ 0.05. The method indicated a good overall reliability (LOA = ± 0.61° C, CV = 0.58%, SEM = 0.12° C, Cohen's d = 0.12, r = 0.84, ICC = 0.84). Analysis revealed a statistically significant (p = 0.02) mean systematic bias of -0.07 ± 0.31° C, and the investigation of the Bland-Altman plot suggested the presence of heteroscedasticity. Further analysis revealed the minimum "likely" change in intestinal temperature to be 0.34° C. Although the method demonstrates a good reliability, researchers should be aware of heteroscedasticity. Changes in intestinal temperature >0.34° C as a result of exercise or an intervention in a hot environment are likely changes and less influenced by error associated with the method.

The pollen complex from postglacial sediments of the Laptev Sea as a bioindicator

NASA Astrophysics Data System (ADS)

Naidina, O. D.

2014-05-01

The first results of comparison of palynological analysis (pollen of terrestrial plants), SEM analysis of pollen morphology, and radiocarbon age dating (AMS14C) of sediments of the eastern shelf of the Laptev Sea show that the diverse taxonomic composition of pollen spectra provides an integrated idea of the vegetation and climate of the region over 11.2 calendar kiloyears. It is found that phases of the tree and shrub vegetation development (maxima of pollen of Betula sect. Nanae and Pinus s/g Haploxylon) correspond to the warm epochs in the Holocene. It is obvious that birch phytocoenoses first settled in the southern tundra subzone with increasing temperature, and then coniferous communities of forest tundra. An occurrence of pollen of shrubby birches (Nanae) suggests compliance of permafrost landscapes with cold climate conditions, i.e., with an annual average temperature of -2°C and amount of precipitation of less than 500 mm. Owing to a progressive increase in summer temperatures, dwarf cedar and pine communities advanced toward the seashore. The SEM analysis results show that a significant proportion of regional coniferous pollen belongs to representatives of Pinus pumila (Pall.) and P. sylvestris L. In addition, the SEM study of the exine of Pinus sylvestris L. and P. pumila (Pall.) Regel pollen grains confirmed polymorphism in coniferous pollen. According to the inverse relationship between climate and vegetation, frequent climate fluctuations that are typical of progressive and differential postglacial transgression were revealed. An increase in arboreal pollen transfer onto the shelf later than 9.1 cal. ka coincides with the time of forest boundary migration to the north due to the warming of the Earth's climate. At that time, the tundra vegetation was replaced by forest-tundra vegetation, the maximum stage of sea transgression began, and there appeared a trend of increasing temperature and moisture.

SEM Imaging and Chemical Analysis of Aerosol Particles from Surface and Hi-altitudes in New Jersey.

NASA Astrophysics Data System (ADS)

Bandamede, M.; Boaggio, K.; Bancroft, L.; Hurler, K.; Magee, N. B.

2016-12-01

We report on Scanning Electron Microscopy analysis of aerosol particle morphology and chemistry. The work includes the first comparative SEM analysis of aerosol particles captured by balloon at high altitude. The particles were acquired in an urban/suburban environment in central New-Jersey. Particles were sampled from near the surface using ambient air filtration and at high-altitudes using a novel balloon-borne instrument (ICE-Ball, see abstract by K. Boaggio). Particle images and 3D geometry are acquired by a Hitachi SU-5000 SEM, with resolution to approximately 3 nm. Elemental analysis on particles is provided by Energy Dispersive X-Ray Spectroscopy (EDS, EDAX, Inc.). Uncoated imaging is conducted in low vacuum within the variable-pressure SEM, which provides improved detection and analysis of light-element compositions including Carbon. Preliminary results suggest that some similar particle types and chemical species are sampled at both surface and high-altitude. However, as expected, particle morphologies, concentrations, chemistry, and apparent origin vary significantly at different altitudes and under different atmospheric flow regimes. Improved characterization of high-altitude aerosol particles, and differences from surface particulate composition, may advance inputs for atmospheric cloud and radiation models.

Environmental scanning electron microscope imaging examples related to particle analysis.

PubMed

Wight, S A; Zeissler, C J

1993-08-01

This work provides examples of some of the imaging capabilities of environmental scanning electron microscopy applied to easily charged samples relevant to particle analysis. Environmental SEM (also referred to as high pressure or low vacuum SEM) can address uncoated samples that are known to be difficult to image. Most of these specimens are difficult to image by conventional SEM even when coated with a conductive layer. Another area where environmental SEM is particularly applicable is for specimens not compatible with high vacuum, such as volatile specimens. Samples from which images were obtained that otherwise may not have been possible by conventional methods included fly ash particles on an oiled plastic membrane impactor substrate, a one micrometer diameter fiber mounted on the end of a wire, uranium oxide particles embedded in oil-bearing cellulose nitrate, teflon and polycarbonate filter materials with collected air particulate matter, polystyrene latex spheres on cellulosic filter paper, polystyrene latex spheres "loosely" sitting on a glass slide, and subsurface tracks in an etched nuclear track-etch detector. Surface charging problems experienced in high vacuum SEMs are virtually eliminated in the low vacuum SEM, extending imaging capabilities to samples previously difficult to use or incompatible with conventional methods.

Indium hexagonal island as seed-layer to boost a-axis orientation of AlN thin films

NASA Astrophysics Data System (ADS)

Redjdal, N.; Salah, H.; Azzaz, M.; Menari, H.; Manseri, A.; Guedouar, B.; Garcia-Sanchez, A.; Chérif, S. M.

2018-06-01

Highly a-axis oriented aluminum nitride films have been grown on Indium coated (100) Si substrate by DC reactive magnetron sputtering. It is shown that In incorporated layer improve the extent of preferential growth along (100) axis and form dense AlN films with uniform surface and large grains, devoid of micro-cracks. As revealed by SEM cross section images, AlN structure consists of oriented columnar grains perpendicular to the Si surface, while AlN/In structure results in uniformely tilted column. SEM images also revealed the presence of In hexagonal islands persistent throughout the entire growth. Micro -Raman spectroscopy of the surface and the cross section of the AlN/In grown films evidenced their high degree of homogeneity and cristallinity.

Automated SEM and TEM sample preparation applied to copper/low k materials

NASA Astrophysics Data System (ADS)

Reyes, R.; Shaapur, F.; Griffiths, D.; Diebold, A. C.; Foran, B.; Raz, E.

2001-01-01

We describe the use of automated microcleaving for preparation of both SEM and TEM samples as done by SELA's new MC500 and TEMstation tools. The MC500 is an automated microcleaving tool that is capable of producing cleaves with 0.25 μm accuracy resulting in SEM-ready samples. The TEMstation is capable of taking a sample output from the MC500 (or from SELA's earlier MC200 tool) and producing a FIB ready slice of 25±5 μm, mounted on a TEM-washer and ready for FIB thinning to electron transparency for TEM analysis. The materials selected for the tool set evaluation mainly included the Cu/TaN/HOSP low-k system. The paper is divided into three sections, experimental approach, SEM preparation and analysis of HOSP low-k, and TEM preparation and analysis of Cu/TaN/HOSP low-k samples. For the samples discussed, data is presented to show the quality of preparation provided by these new automated tools.

Demographics and sexual characteristics of sex-enhancing medication users: Study of a web-based cross-sectional sample of sexually active men.

PubMed

Ahmed, Abul-Fotouh; Alshahrani, Saad; Morgan, Anthony; Gabr, Ahmed H; Abdel-Razik, Mohamed; Daoud, Abdallah

2017-12-01

To evaluate the frequency of sex-enhancing medications (S-EM) use and to investigate the demographics and sexual characteristics of the S-EM users amongst a Saudi Arabian male population. A cross-sectional sample of 1176 Saudi Arabian men was recruited using a web-based survey between 1 January and 1 April 2015. The survey included multiple open and closed questions to assess the frequency of S-EM use; and demographics, clinical, and sexual characteristics of S-EM users, as well as their perceptions of S-EM. Amongst the participants, 1008 were sexually active and included in the data analysis. Of the sexually active participants, 402 (39.9%) reported S-EM use in the form of herbal or phosphodiesterase type 5 inhibitors at some time in their lives. Comparing S-EM users with S-EM non-users, the S-EM users had a number of demographic and sexual characteristics including: higher education level, higher income, smoking, more than one sexual partner, longer sexual activity duration, higher frequency of sexual intercourse, and lower sexual satisfaction level. Most of the S-EM users (82.1%) bought S-EM without a medical prescription and 62.5% had used them recreationally. In all, 52% of respondents used S-EM to treat ED and 69% of those who used it recreationally reported enhancement of erection with S-EM usage. Demographic and sexual characteristics of S-EM users and the attitude of the users towards the S-EM were identified amongst a Saudi Arabian male population.

Relationship between borderline personality symptoms and Internet addiction: The mediating effects of mental health problems.

PubMed

Lu, Wei-Hsin; Lee, Kun-Hua; Ko, Chih-Hung; Hsiao, Ray C; Hu, Huei-Fan; Yen, Cheng-Fang

2017-09-01

Aim To examine the relationship between borderline personality symptoms and Internet addiction as well as the mediating role of mental health problems between them. Methods A total of 500 college students from Taiwan were recruited and assessed for symptoms of Internet addiction using the Chen Internet Addiction Scale, borderline personality symptoms using the Taiwanese version of the Borderline Symptom List and mental health problems using four subscales from the Symptom Checklist-90-Revised Scale (interpersonal sensitivity, depression, anxiety, and hostility). Structural equation modeling (SEM) was used to test our hypothesis that borderline personality symptoms are associated with the severity of Internet addiction directly and also through the mediation of mental health problems. Results SEM analysis revealed that all paths in the hypothesized model were significant, indicating that borderline personality symptoms were directly related to the severity of Internet addiction as well as indirectly related to the severity of Internet addiction by increasing the severity of mental health problems. Conclusion Borderline personality symptoms and mental health problems should be taken into consideration when designing intervention programs for Internet addiction.

Monodisperse ferrous phosphate colloids in an anoxic groundwater plume

USGS Publications Warehouse

Gschwend, Philip M.; Reynolds, Matthew D.

1987-01-01

Groundwater samples collected near a secondary-sewage infiltration site on Cape Cod, Massachusetts were examined for colloidal materials (10–1000 nm). In two wells the water contained a population of monodisperse 100-nm particles, detected using laser-light scattering and autocorrelation data processing. SEM and SEM-EDAX analysis of these colloidal materials collected on ultrafilters confirmed the laser light scattering result and revealed that these microparticles consisyed of primarily iron and phosphorus in a 1.86 Fe to 1.0 P stoichiometric ratio. Chemical analyses of the water samples, together with equilibrium solubility calculations, strongly suggest that the ion-activity product should exceed the solubility product of a 100-nm diameter predominantly vivianite-type (Fe3(PO4)2 · 8H2O) colloidal phase. In light of our results, we conclude that these microparticles were formed by sewage-derived phosphate combining with ferrous iron released from the aquifer solids, and that these colloids may be moving in the groundwater flow. Such a subsurface transport process could have major implications regarding the movement of particle-reactive pollutants traditionally viewed as non-mobile in groundwater.

Tribological and corrosion behaviour of electroless Ni-B coating possessing a blackberry like structure

NASA Astrophysics Data System (ADS)

Bülbül, Ferhat; Altun, Hikmet; Küçük, Özkan; Ezirmik, Vefa

2012-08-01

This study aims to evaluate the tribological and corrosion properties of the electroless Ni-B coating deposited on AISI 304 stainless steels. The microstructure of the coating was characterized using x-ray diffraction (XRD) and scanning electron microscopy-energy dispersive spectrometry (SEM-EDS). XRD analysis revealed that the prepared coating possessed an amorphous character. SEM-EDS investigation also indicated that a non-stoichiometric Ni-B coating was deposited with a columnar growth mechanism on the stainless steel substrate and the morphology of the growth surface was blackberry-like. The hardness and tribological properties were characterized by microhardness and a pin-on-disc wear test. The electroless Ni-B coated sample had a higher degree of hardness, a lower friction coefficient and a lower wear rate than the uncoated substrate. The electrochemical potentiodynamic polarization method was used to evaluate the corrosion resistance of the coating. The electroless Ni-B coating offered cathodic protection on the substrate by acting as a sacrificial anode although it was electrochemically more reactive than the stainless steel substrate.

Facile fabrication of ultrathin hybrid membrane for highly flexible supercapacitors via in-situ phase separation of polyethersulfone

NASA Astrophysics Data System (ADS)

Zhao, Xiaoning; Ran, Fen; Shen, Kuiwen; Yang, Yunlong; Wu, Jiayu; Niu, Xiaoqin; Kong, Lingbin; Kang, Long; Chen, Shaowei

2016-10-01

In this article, a facile method based on in-situ phase-separation was developed for the fabrication of ultrathin hybrid membranes for highly flexible supercapacitors. The structures and morphologies of the prepared electrodes were characterized by scanning electron microscopy (SEM), Fourier-transformed infrared spectroscopy (FTIR), and thermogravimetric analysis (TGA) measurements; and the electrochemical behaviors were examined in 2 M KOH solution. SEM and FTIR characterizations reveal that activated carbon was imbedded into the polymer membrane of polyethersulfone to form a uniform and flexible hybrid membrane. When the thin polymer-carbon membrane (PCM) was used as an electrode material for supercapacitor, a high specific capacitance of 169.4 Fg-1 was obtained at a current density of 0.5 Ag-1 along with good long-term cycle life of 94.6% capacity retention after 2000 charging-discharging cycles. Benefiting from these merits, the as-fabricated PCM//PCM cell shows an excellent electrochemical property. These results suggest a promising route towards the fabrication of highly flexible electrodes for high-performance supercapacitors.

Chain length effect on the structure and stability of antimicrobial peptides of the (RW)n series.

PubMed

Phambu, Nsoki; Almarwani, Bashiyar; Garcia, Arlette M; Hamza, Nafisa S; Muhsen, Amira; Baidoo, Jacqueline E; Sunda-Meya, Anderson

2017-08-01

Three peptides containing (RW) n -NH 2 units (where n=4, 6, and 8) have been chosen to study the effect of the chain length on the structure and stability of the peptide using Fourier transform infrared (FTIR), scanning electron microscopy (SEM), thermogravimetric analysis (TGA), and differential scanning calorimetry (DSC) techniques. Their interactions with Escherichia coli (E. coli) membrane mimetic vesicles are discussed. Infrared results indicate that addition of (RW) n -NH 2 units increases intermolecular H bonds with antiparallel orientation. TGA and DSC results reveal that (RW) 6 -NH 2 shows the optimal chain length in terms of stability and all three peptides show a preferential interaction with one of the anionic lipids in E. coli membranes. SEM images of (RW) 4 -NH 2 present large aggregates while those of (RW) 6 -NH 2 and (RW) 8 -NH 2 present layers of sheet-like structure. In the presence of model membranes, (RW) n -NH 2 show fibrillar peptide superstructures. This study suggests that repeating structures of (RW) n -NH 2 promotes lateral assembly. Copyright © 2017 Elsevier B.V. All rights reserved.

Using SEM Analysis on Ion-Milled Shale Surface to Determine Shale-Fracturing Fluid Interaction

NASA Astrophysics Data System (ADS)

Lu, J.; Mickler, P. J.; Nicot, J. P.

2014-12-01

It is important to document and assess shale-fluid interaction during hydraulic fracturing (HF) in order to understand its impact on flowback water chemistry and rock property. A series of autoclave experiments were conducted to react shale samples from major oil and gas shales with synthetic HF containing various additives. To better determine mineral dissolution and precipitation at the rock-fluid interface, ion-milling technique was applied to create extremely flat rock surfaces that were examined before and after the autoclave experiments using a scanning electron microscope (SEM) coupled with energy dispersive spectroscopy (EDS) detectors. This method is able to reveal a level of detail not observable on broken surface or mechanically polished surface. It allows direct comparison of the same mineral and organic matter particles before and after the reaction experiments. Minerals undergone dissolution and newly precipitated materials are readily determined by comparing to the exact locations before reaction. The dissolution porosity and the thickness of precipitates can be quantified by tracing and measuring the geometry of the pores and precipitates. Changes in porosity and permeability were confirmed by mercury intrusion capillary tests.

Rapid extra-/intracellular biosynthesis of gold nanoparticles by the fungus Penicillium sp.

NASA Astrophysics Data System (ADS)

Du, Liangwei; Xian, Liang; Feng, Jia-Xun

2011-03-01

In this work, the fungus Penicillium was used for rapid extra-/intracellular biosynthesis of gold nanoparticles. AuCl4 - ions reacted with the cell filtrate of Penicillium sp. resulting in extracellular biosynthesis of gold nanoparticles within 1 min. Intracellular biosynthesis of gold nanoparticles was obtained by incubating AuCl4 - solution with fungal biomass for 8 h. The gold nanoparticles were characterized by means of visual observation, UV-Vis absorption spectroscopy, X-ray diffraction (XRD), transmission electron microscopy (TEM), scanning electron microscopy (SEM), and energy-dispersive X-ray spectroscopy (EDX). The extracellular nanoparticles exhibited maximum absorbance at 545 nm in UV-Vis spectroscopy. The XRD spectrum showed Bragg reflections corresponding to the gold nanocrystals. TEM exhibited the formed spherical gold nanoparticles in the size range from 30 to 50 nm with an average size of 45 nm. SEM and TEM revealed that the intracellular gold nanoparticles were well dispersed on the cell wall and within the cell, and they are mostly spherical in shape with an average diameter of 50 nm. The presence of gold was confirmed by EDX analysis.

Measuring topographies from conventional SEM acquisitions.

PubMed

Shi, Qiwei; Roux, Stéphane; Latourte, Félix; Hild, François; Loisnard, Dominique; Brynaert, Nicolas

2018-04-27

The present study extends the stereoscopic imaging principle for estimating the surface topography to two orientations, namely, normal to the electron beam axis and inclined at 70° as suited for EBSD analyses. In spite of the large angle difference, it is shown that the topography can be accurately determined using regularized global Digital Image Correlation. The surface topography is compared to another estimate issued from a 3D FIB-SEM procedure where the sample surface is first covered by a Pt layer, and its initial topography is progressively revealed from successive FIB-milling. These two methods are successfully compared on a 6% strained steel specimen in an in situ mechanical test. This analysis is supplemented by a third approach estimating the change of topography from crystal rotations as measured from successive EBSD images. This last technique ignores plastic deformation, and thus only holds in an elastic regime. For the studied example, despite the large plastic flow, it is shown that crystal rotation already accounts for a significant part of the deformation-induced topography. Copyright © 2018 Elsevier B.V. All rights reserved.

Sb-Te alloy nanostructures produced on a graphite surface by a simple annealing process

NASA Astrophysics Data System (ADS)

Kuwahara, Masashi; Uratsuji, Hideaki; Abe, Maho; Sone, Hayato; Hosaka, Sumio; Sakai, Joe; Uehara, Yoichi; Endo, Rie; Tsuruoka, Tohru

2015-08-01

We have produced Sb-Te alloy nanostructures from a thin Sb2Te3 layer deposited on a highly oriented pyrolytic graphite substrate using a simple rf-magnetron sputtering and annealing technique. The size, shape, and chemical composition of the structures were investigated by scanning electron microscopy (SEM), atomic force microscopy (AFM), and energy dispersive X-ray spectrometry (EDX), respectively. The shape of the nanostructures was found to depend on the annealing temperature; nanoparticles appear on the substrate by annealing at 200 °C, while nanoneedles are formed at higher temperatures. Chemical composition analysis has revealed that all the structures were in the composition of Sb:Te = 1:3, Te rich compared to the target composition Sb2Te3, probably due to the higher movability of Te atoms on the substrate compared with Sb. We also tried to observe the production process of nanostructures in situ using SEM. Unfortunately, this was not possible because of evaporation in vacuum, suggesting that the formation of nanostructures is highly sensitive to the ambient pressure.

Anticorrosion Coating using Olea sp. Leaves Extract

NASA Astrophysics Data System (ADS)

Ikhmal, W. M. K. W. M.; Yasmin, M. Y. N.; Fazira, M. F. M.; Rafizah, W. A. W.; Nik, W. B. Wan; Sabri, M. G. M.

2018-04-01

Olive leaves extract (OLE) was evaluated as green corrosion inhibitor for stainless steel grade 316L (SS316L) in several media using scanning electron microscope (SEM), electrochemical impedance spectroscopy (EIS) and potentiodynamic polarization techniques. The Fourier Transform Infrared (FTIR) spectroscopy results reveals several active compound indicated by O-H stretch, C=O stretch, C-OH stretch and C-N stretch which can be attributed to oleuropein and hydroxtyrosol acting as the main inhibiting sources for corrosion. The results obtained also show the inhibition efficiency of OLE increase with the increase of OLE concentration. Through its inhibitive action elucidate from the electrochemical analysis, the extract was found to act as a mixed type inhibitor. Micrographs by SEM showed that the surface of steel which has been coated with 0% and 20% of OLE coating extract possess a lot of pin holes or pores while the steel with 10% of OLE coating extract shows the surface has multiple cracks. This study clearly shows the efficiency of OLE as anticorrosion coating for control of stainless steel in marine application.

Genotype-dependent efficiency of endosperm development in culture of selected cereals: histological and ultrastructural studies.

PubMed

Popielarska-Konieczna, Marzena; Kozieradzka-Kiszkurno, Małgorzata; Tuleja, Monika; Ślesak, Halina; Kapusta, Paweł; Marcińska, Izabela; Bohdanowicz, Jerzy

2013-02-01

The paper reports studies, including histological and ultrastructural analyses, of in vitro cell proliferation and development of immature endosperm tissue isolated from caryopses of Triticum aestivum, Triticum durum, and Triticosecale plants. Endosperm isolated at 7-10 days post-anthesis developed well on MS medium supplemented with auxins and/or cytokinins. The efficiency of endosperm response was highly genotype-dependent and best in two winter cultivars of hexaploid species. The pathways of development and proliferation were very similar among the selected species and cultivars. Histological and scanning electron microscope (SEM) analysis revealed that only the part of the endosperm not touching the medium surface continued growth and development, resulting in swelling. The central part of swollen regions was composed mainly of cells containing many large starch grains. The peripheric parts of developed endosperm consisted of highly vacuolated cells and small cells with dense cytoplasm. SEM showed that cells from the swollen region were covered partially with a membraneous structure. Transmission electron microscope studies of cells from the outer part of the developing region showed features typical for cell activity connected with lipid metabolism.

A novel biphasic calcium phosphate derived from fish otoliths

NASA Astrophysics Data System (ADS)

Montañez-Supelano, N. D.; Sandoval-Amador, A.; Estupiñan-Durán, H. A.; Y Peña-Ballesteros, D.

2017-12-01

Calcium phosphates are bioceramics that have been widely used as bone substitutes because they encourage the formation of bone on their surface and can improve the healing of the bone. Hydroxyapatite HA (calcium/phosphorus ratio of 1.67) and tricalcium phosphate TCP (calcium/phosphorus ratio of 1.50) are the most common calcium phosphates. Natural materials have begun to be tested to make HA or TCP such as shells of cardiidae (family of mollusks) and eggshells. The calcium phosphate obtained has a high ability to precipitate apatite. In this work, the mixed phase ceramic of beta-Tri-calcium phosphate / hydroxyapatite (β-TCP/HA) was synthesized by aqueous precipitation from fish otoliths, which are monomineralic species composed of aragonite. Otoliths of the specie Plagioscion squamosissimus, commonly called the river croaker, were used. Techniques such as DRX, Raman spectroscopy and SEM-EDS were used to characterize the raw material and the obtained material. X-ray diffraction analysis revealed the presence of two crystalline phases of calcium phosphates with 86.2% crystallinity. SEM micrographs showed agglomeration of particles with porous structure and submicron particle sizes.

Role of SrO on the bioactivity behavior of some ternary borate glasses and their glass ceramic derivatives

NASA Astrophysics Data System (ADS)

Abdelghany, A. M.; Ouis, M. A.; Azooz, M. A.; ElBatal, H. A.; El-Bassyouni, G. T.

2016-01-01

Borate glasses containing SrO substituting both CaO and NaO were prepared and characterized for their bioactivity or bone bonding ability. Glass ceramic derivatives were prepared by thermal heat treatment process. FTIR, XRD and SEM measurements for the prepared glass and glass-ceramics before and after immersion in sodium phosphate solution for one and two weeks were carried out. The appearance of two IR peaks within the range 550-680 cm-1 after immersion in phosphate solution indicates the formation of hydroxyapatite or equivalent Sr phosphate layer. X-ray diffraction data agree with the FTIR spectral analysis. The solubility test was carried out for both glasses and glass ceramics derivatives in the same phosphate solution. The introduction of SrO increases the solubility for both glasses and glass ceramics and this is assumed to be due to the formation of Sr phosphate which is more soluble than calcium phosphate (hydroxyapatite). SEM images reveal varying changes in the surfaces of glass ceramics after immersion according to the SrO content.

Preparation and biocompatibility study of in situ forming polymer implants in rat brains.

PubMed

Nasongkla, Norased; Boongird, Atthaporn; Hongeng, Suradej; Manaspon, Chawan; Larbcharoensub, Noppadol

2012-02-01

We describe the development of polymer implants that were designed to solidify once injected into rat brains. These implants comprised of glycofurol and copolymers of D: ,L: -lactide (LA), ε-caprolactone and poly(ethylene glycol) (PLECs). Scanning electron microscopy (SEM) and gel permeation chromatography (GPC) showed that the extent of implant degradation was increased with LA: content in copolymers. SEM analysis revealed the formation of porosity on implant surface as the degradation proceeds. PLEC with 19.3% mole of LA: was chosen to inject in rat brains at the volume of 10, 25 and 40 μl. Body weights, hematological and histopathological data of rats treated with implants were evaluated on day 3, 6, 14, 30 and 45 after the injection. Polymer solution at the injection volume of 10 μl were tolerated relatively well compared to those of 25 and 40 μl as confirmed by higher body weight and healing action (fibrosis tissue) 30 days after treatment. The results from this study suggest a possible application as drug delivery systems that can bypass the blood brain barrier.

Characterization of Antibiotic-Loaded Alginate-Osa Starch Microbeads Produced by Ionotropic Pregelation

PubMed Central

Fontes, Gizele Cardoso; Calado, Verônica Maria Araújo; Rossi, Alexandre Malta; da Rocha-Leão, Maria Helena Miguez

2013-01-01

The aim of this study was to characterize the penicillin-loaded microbeads composed of alginate and octenyl succinic anhydride (OSA) starch prepared by ionotropic pregelation with calcium chloride and to evaluate their in vitro drug delivery profile. The beads were characterized by size, scanning electron microscopy (SEM), zeta potential, swelling behavior, and degree of erosion. Also, the possible interaction between penicillin and biopolymers was investigated by differential scanning calorimetry (DSC), powder X-ray diffraction (XRD), and Fourier transform infrared (FTIR) analysis. The SEM micrograph results indicated a homogeneous drug distribution in the matrix. Also, based on thermal analyses (TGA/DSC), interactions were detected between microbead components. Although FTIR spectra of penicillin-loaded microbeads did not reveal the formation of new chemical entities, they confirmed the chemical drug stability. XRD patterns showed that the incorporated crystalline structure of penicillin did not significantly alter the primarily amorphous polymeric network. In addition, the results confirmed a prolonged penicillin delivery system profile. These results imply that alginate and OSA starch beads can be used as a suitable controlled-release carrier for penicillin. PMID:23862146

Electrodeposition of Nanocrystalline Ni–Fe Alloy Coatings Based on 1-Butyl-3-Methylimidazolium-Hydrogen Sulfate Ionic Liquid.

PubMed

He, Xinkuai; Zhang, Chuang; Zhu, Qingyun; Lu, Haozi; Cai, Youxing; Wu, Luye

2017-02-01

The electrodeposition of nanocrystalline Ni–Fe alloy coatings and associated nucleation/growth processes are investigated on the glassy carbon (GC) electrode in 1-butyl-3-methylimidazolium-hydrogen sulfate ([BMIM]HSO4) ionic liquid (IL). Cyclic voltammetric data suggest that the co-electrodeposition of Ni–Fe alloys is quasi-reversible. Moreover, chronoamperometry results indicate that the electrodeposition proceeds via a simultaneous nucleation and three-dimensional growth mechanism. In addition, the effects of electrodeposition potential and electrolyte temperature on the coating thickness and Fe content are also studied. The microstructure and composition of the Ni–Fe alloy coatings on Cu substrate are investigated using scanning electron microscopy (SEM), X-ray diffraction (XRD) and energy-dispersive spectroscopy (EDS). SEM observations show that these electrodeposits present a dense and compact structure, EDS analysis indicates that the coatings are composed of Ni and Fe, XRD pattern shows the coatings are crystalline with a face-centred cubic (fcc) structure. Tafel plots reveal that the Ni–Fe alloy prepared from [BMIM]HSO4 IL presents better corrosion resistance than that of pure Ni.

Synthesis and Characterization of Titanium Dioxide Thin Film for Sensor Applications

NASA Astrophysics Data System (ADS)

Latha, H. K. E.; Lalithamba, H. S.

2018-03-01

Titanium oxide (TiO2) nanoparticles (metal oxide semiconductor) are successfully synthesized using hydrothermal method for sensor application. Titanium dioxide and Sodium hydroxide are used as precursors. These reactants are mixed and calcinated at 400 °C to produce TiO2 nanoparticles. The crystalline structure, morphology of synthesized TiO2 nanoparticles are studied using x-ray diffraction (XRD), Fourier Transform Infrared (FTIR) analysis and scanning electron microscopy (SEM). XRD results revealed that the prepared TiO2 sample is highly crystalline, having Anatase crystal structure. FT-IR spectra peak at 475 cm‑1 indicated characteristic absorption bands of TiO2 nanoparticles. The XRD and FTIR result confirmed the formation of high purity of TiO2 nanoparticles. The SEM image shows that TiO2 nanoparticles prepared in this study are spherical in shape. Synthesized TiO2 nanoparticles are deposited on glass substrate at room temperature using E beam evaporation method to determine gauge factor and found to be 4.7. The deposited TiO2 thin films offer tremendous potential in the applications of electronic and magneto–electric devices.

Extraction of high value added gelatin biopolymer from black tilapia (Oreochromis mossambicus) head bones

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

Sockalingam, K., E-mail: gd130106@siswa.uthm.edu.my; Abdullah, H. Z., E-mail: hasan@uthm.edu.my

Black tilapia (Oreochromis mossambicus) fish head bones were evaluated for its possibilities in extracting gelatin. Head bones were subjected to pre-treatment with 3% of hydrochloric acid (HCl) for demineralization before undergoes thermal extraction process. The raw head bones were characterized via Scanning Electron Microscopy (SEM) in order to investigate the external and internal surface morphology. SEM images also reveal the presence of collagen fiber with 1 µm diameter in the head bone. The black tilapia fish head bones yields 5.75 % of gelatin in wet weight basis, indicating the possibility of this fish species as sources of gelatin. Further characterizations weremore » done on both raw head bones and extracted gelatin through Fourier Transform Infrared Spectroscopy (FTIR) and proximate analysis. The head bones gelatin shows high protein (10.55%) and ash (3.11 %) content with low moisture. This further proves the effectiveness of demineralization and extraction method used. The black tilapia fish head bones are found to be a prospective source of gelatin with good chemical and functional properties.« less

A new method of nanocrystalline nickel powder formation by magnetron sputtering on the water-soluble substrates

NASA Astrophysics Data System (ADS)

Tučkutė, S.; Urbonavičius, M.; Lelis, M.; Maiorov, M.; Díaz Ordaz, J. R.; Milčius, D.

2018-01-01

Due to the accurate and relatively easy control magnetron sputtering is an attractive technique for the synthesis of metallic particles. This work describes a new method of nickel powder production by depositing nickel on the surface of sodium chloride particles which were used as the template and are soluble in water. Ni powder with flake-like structure was obtained after washing Ni coated salt particles in ultrasonic cleaner. Salt particles and nickel powder were characterized using scanning electron microscope (SEM), energy-dispersive x-ray spectrometer, XRD and X-ray photoelectron spectroscopy (XPS) techniques. SEM images showed that thickness of the received Ni particles varied in the nanoscale and depended on the magnetron deposition time but did not depend on the size of salt particles. On the other hand initial size of the salt particles was successfully employed a measure to control lateral dimensions of Ni powder. XRD and XPS analysis results revealed that Ni particles had metallic core and oxidized shell which was a cause of the slightly deteriorated magnetic properties.

Plasma Electrolytic Oxidation Coatings on Pure Ti Substrate: Effects of Na3PO4 Concentration on Morphology and Corrosion Behavior of Coatings in Ringer's Physiological Solution

NASA Astrophysics Data System (ADS)

Roknian, Masoud; Fattah-alhosseini, Arash; Gashti, Seyed Omid

2018-03-01

Plasma electrolytic oxidation has been used as a relatively new method for applying ceramic coatings having different features. In the present study, commercially pure titanium is used as substrate, and effects of trisodium phosphate electrolyte concentration on the microstructure, as well as corrosion behavior of the coating in Ringer's physiological solution are investigated. The morphology and phase compositions of coatings were analyzed by using scanning electron microscopy (SEM) and x-ray diffraction patterns. The study on the corrosion behavior of samples in a Ringer's physiological solution was carried out using open-circuit potential potentiodynamic polarization and electrochemical impedance spectroscopy. The results of electrochemical analysis proved that higher concentration of phosphate electrolyte leads to increase in the corrosion resistance of applied coatings. Accordingly, obtained results revealed that the optimum electrolyte concentration for the best corrosion behavior was 20 g L-1. Furthermore, SEM images and reduction in the dielectric breakdown potential indicated that increase in the electrolyte concentration leads to morphological improvement and smoothening of the surface.

Retentive force and microleakage of stainless steel crowns cemented with three different luting agents.

PubMed

Yilmaz, Yucel; Dalmis, Anya; Gurbuz, Taskin; Simsek, Sera

2004-12-01

The aim of this investigation was to compare the tensile strength, microleakage, and Scanning Electron Microscope (SEM) evaluations of SSCs cemented using different adhesive cements on primary molars. Sixty-three extracted primary first molars were used. Tooth preparations were done. Crowns were altered and adapted for investigation purpose, and then cemented using glass ionomer cement (Aqua Meron), resin modified cement (RelyX Luting), and resin cement (Panavia F) on the prepared teeth. Samples were divided into two groups of 30 samples each for tensile strength and microleakage tests. The remaining three samples were used for SEM evaluation. Data were analyzed with one-way ANOVA and Tukey test. The statistical analysis of ANOVA revealed significant differences among the groups for both tensile strength and microleakage tests (p < 0.05). Tukey test showed statistically significant difference between Panavia F and RelyX Luting (p < 0.05), but none between the others (p > 0.05). This study showed that the higher the retentive force a crown possessed, the lower would be the possibility of microleakage.

Cyanidation Study of Slag Rich in Silver

NASA Astrophysics Data System (ADS)

Pérez-Labra, Miguel; Romero-Serrano, J. Antonio; Ávila-Davila, E. O.; Reyes-Pérez, M.; Barrientos-Hernández, F. R.; Hernández, I. A. Lira

Slag from smelting reduction processes were characterized by chemical analysis, XRD, SEM-EDS and XRF. The results revealed Ag concentrations of 362 g/t of slag, the slag mineralogical characterization by XRD and SEM-EDS showed mineralogical species oxidized complex containing Pb, Zn, Ca, Si, Fe, As, S in its structure, silver was found in globules associated lead in the slag and the furutobeite specie. The leaching study was conducted to evaluate process variables such as NaCN concentration: from 7.8×10-3M - 1.26×10-1M, temperature: 25-50°C, particle size: +140 mesh to -400 mesh, stirring speed of 750 rpm - 900 rpm. All studies were performed with a NaOH concentration of 0.2 M. The optimal values of silver recovery encountered in conditions of 7.8×10-3M NaCN, agitation rate of 750 rpm, temperature of 35°C and with a treatment time of 240 min. We also observed that a particle size -400 mesh will have optimum recoveries compared to +140 mesh, +200, +270 and +325.

Spectroscopic studies on sidewall carboxylic acid functionalization of multi-walled carbon nanotubes with valine.

PubMed

Deborah, M; Jawahar, A; Mathavan, T; Dhas, M Kumara; Benial, A Milton Franklin

2015-03-15

The valine functionalized multi-walled carbon nanotubes (MWCNTS) were prepared and characterized by using XRD, UV-Vis, FT-IR, EPR, SEM, and EDX, spectroscopic techniques. The enhanced XRD peak (002) intensity was observed for valine functionalized MWCNTs compared with oxidized MWCNTs, which is likely due to sample purification by acid washing. UV-Vis study shows the formation of valine functionalized MWCNTs. FT-IR study confirms the presence of functional groups of oxidized MWCNTs and valine functionalized MWCNTs. The ESR line shape analysis indicates that the observed EPR line shape is a Gaussian line shape. The g-values indicate that the systems are isotropic in nature. The morphology study was carried out for oxidized MWCNTs and valine functionalized MWCNTs by using SEM. The EDX spectra revealed that the high purity of oxidized MWCNTs and valine functionalized MWCNTs. The functionalization has been chosen because, functionalization of CNTs with amino acids makes them soluble and biocompatible. Thus, they have potential applications in the field of biosensors and targeted drug delivery. Copyright © 2014 Elsevier B.V. All rights reserved.

Enhanced Bioavailability and Anticancer Effect of Curcumin-Loaded Electrospun Nanofiber: In Vitro and In Vivo Study

NASA Astrophysics Data System (ADS)

Wang, Chuan; Ma, Chao; Wu, Zhenkai; Liang, He; Yan, Peng; Song, Jia; Ma, Nan; Zhao, Qinghua

2015-11-01

Nanofibers have attracted increasing attention in drug delivery and other biomedical applications due to their some special properties. The present study aims to prepare a fiber-based nanosolid dispersion system to enhance the bioavailability of curcumin (CUR). CUR-loaded polyvinyl pyrrolidone (CUR@PVP) nanofibers were successfully prepared via electrospinning. Scanning electron microscopy (SEM) was employed to observe the morphology of the nanofibers, and the SEM image showed that the drug-loaded nanofibers were smooth, and no CUR clusters were found on the surface of the nanofibers. The results of X-ray diffraction (XRD) demonstrated that the CUR was evenly distributed in the nanofibers in an amorphous state. Fourier transform infrared (FTIR) spectroscopy analysis indicated that intermolecular hydrogen bonding occurred between the CUR and the polymer matrix. In vitro dissolution profiles showed that CUR@PVP nanofiber could be quickly dissolved in phosphate-buffered saline (PBS) solution, while negligible dissolution was observed in pure CUR sample. Importantly, in vitro cell viability assays and in vivo animal tests revealed that the nanosolid dispersion system dramatically enhanced the bioavailability and showed effective anticancer effect of the CUR.

Effect of sonic vibration of an ultrasonic toothbrush on the removal of Streptococcus mutans biofilm from enamel surface.

PubMed

Hashizume, Lina Naomi; Dariva, Alessandra

2015-12-01

To evaluate in vitro the effect of sonic vibration of an ultrasonic toothbrush in the removal of Streptococcus mutans (S. mutans) biofilm from human enamel. S. mutans dental biofilm was formed in vitro on human enamel blocks coated by salivary pellicle. The blocks were incubated with a suspension of S. mutans at 37°C for 24 or 72 hours. The blocks were divided to one of three conditions according to the different toothbrush action modes: ultrasound plus sonic vibration (U+SV), ultrasound-only (U) and no ultrasound and no sonic vibration (control). Samples were exposed to each mode for 3 minutes with the toothbrush bristles placed 5 mm away from the enamel block surface. The samples were observed by scanning electron microscopy (SEM) and quantification of S. mutans was performed. U+SV showed lower bacterial counts compared to U and control on the 72 hour-biofilm (P < 0.05). The SEM analysis revealed that U+SV and U disrupted the S. mutans chains in the 24- and 72-hour biofilm.

Role of SrO on the bioactivity behavior of some ternary borate glasses and their glass ceramic derivatives.

PubMed

Abdelghany, A M; Ouis, M A; Azooz, M A; ElBatal, H A; El-Bassyouni, G T

2016-01-05

Borate glasses containing SrO substituting both CaO and NaO were prepared and characterized for their bioactivity or bone bonding ability. Glass ceramic derivatives were prepared by thermal heat treatment process. FTIR, XRD and SEM measurements for the prepared glass and glass-ceramics before and after immersion in sodium phosphate solution for one and two weeks were carried out. The appearance of two IR peaks within the range 550-680cm(-1) after immersion in phosphate solution indicates the formation of hydroxyapatite or equivalent Sr phosphate layer. X-ray diffraction data agree with the FTIR spectral analysis. The solubility test was carried out for both glasses and glass ceramics derivatives in the same phosphate solution. The introduction of SrO increases the solubility for both glasses and glass ceramics and this is assumed to be due to the formation of Sr phosphate which is more soluble than calcium phosphate (hydroxyapatite). SEM images reveal varying changes in the surfaces of glass ceramics after immersion according to the SrO content. Copyright © 2015 Elsevier B.V. All rights reserved.

Process Parameters on the Crystallization and Morphology of Hydroxyapatite Powders Prepared by a Hydrolysis Method

NASA Astrophysics Data System (ADS)

Wang, Moo-Chin; Hon, Min-Hsiung; Chen, Hui-Ting; Yen, Feng-Lin; Hung, I.-Ming; Ko, Horng-Huey; Shih, Wei-Jen

2013-07-01

The effects of process parameters on the crystallization and morphology of hydroxyapatite (Ca10(PO4)6(OH)2, HA) powders synthesized from dicalcium phosphate dihydrate (CaHPO4·2H2O, DCPD) using a hydrolysis method have been investigated. X-ray diffraction (XRD), Fourier-transform infrared (FT-IR) spectra, scanning electron microscopy (SEM), transmission electron microscopy (TEM), and selected area electron diffraction (SAED) were used to characterize the synthesized powders. When DCPD underwent hydrolysis in 2.5 NaOH solution (Na(aq)) at 303 K to 348 K (30 °C to 75 °C) for 1 hour, the XRD results revealed that HA was obtained for all the as-dried samples. The SEM morphology of the HA powders for DCPD hydrolysis produced at 348 K (75 °C) shows regular alignment and a short rod shape with a size of 200 nm in length and 50 nm in width. With DCPD hydrolysis in 2.5 M NaOH(aq) holding at 348 K (75 °C) for 1 to 24 hours, XRD results demonstrated that all samples were HA and no other phases could be detected. Moreover, the XRD results also show that all the as-dried powders still maintained the HA structure when DCPD underwent hydrolysis in 0.1 to 5 M NaOH(aq) at 348 K (75 °C) for 1 hour. Otherwise, the full transformation from HA to octa-calcium phosphate (OCP, Ca8H2(PO4)6·5H2O) occurred when hydrolysis happened in 10 M NaOH(aq). FT-IR spectra analysis revealed that some carbonated HA (Ca10(PO4)6(CO3), CHA) had formed. The SEM morphology results show that the 60 to 65 nm width of the uniformly long rods with regular alignment formed in the HA powder aggregates when DCPD underwent hydrolysis in 2.5 M NaOH(aq) at 348 K (75 °C) for 1 hour.

Molecular and Microscopic Analysis of Bacteria and Viruses in Exhaled Breath Collected Using a Simple Impaction and Condensing Method

PubMed Central

Xu, Zhenqiang; Shen, Fangxia; Li, Xiaoguang; Wu, Yan; Chen, Qi; Jie, Xu; Yao, Maosheng

2012-01-01

Exhaled breath condensate (EBC) is increasingly being used as a non-invasive method for disease diagnosis and environmental exposure assessment. By using hydrophobic surface, ice, and droplet scavenging, a simple impaction and condensing based collection method is reported here. Human subjects were recruited to exhale toward the device for 1, 2, 3, and 4 min. The exhaled breath quickly formed into tiny droplets on the hydrophobic surface, which were subsequently scavenged into a 10 µL rolling deionized water droplet. The collected EBC was further analyzed using culturing, DNA stain, Scanning Electron Microscope (SEM), polymerase chain reaction (PCR) and colorimetry (VITEK 2) for bacteria and viruses. Experimental data revealed that bacteria and viruses in EBC can be rapidly collected using the method developed here, with an observed efficiency of 100 µL EBC within 1 min. Culturing, DNA stain, SEM, and qPCR methods all detected high bacterial concentrations up to 7000 CFU/m3 in exhaled breath, including both viable and dead cells of various types. Sphingomonas paucimobilis and Kocuria variants were found dominant in EBC samples using VITEK 2 system. SEM images revealed that most bacteria in exhaled breath are detected in the size range of 0.5–1.0 µm, which is able to enable them to remain airborne for a longer time, thus presenting a risk for airborne transmission of potential diseases. Using qPCR, influenza A H3N2 viruses were also detected in one EBC sample. Different from other devices restricted solely to condensation, the developed method can be easily achieved both by impaction and condensation in a laboratory and could impact current practice of EBC collection. Nonetheless, the reported work is a proof-of-concept demonstration, and its performance in non-invasive disease diagnosis such as bacterimia and virus infections needs to be further validated including effects of its influencing matrix. PMID:22848436

Morphology of the European species of the aphid genus Eulachnus (Hemiptera: Aphididae: Lachninae) - A SEM comparative and integrative study.

PubMed

Kanturski, Mariusz; Karcz, Jagna; Wieczorek, Karina

2015-09-01

Scanning electron microscopy (SEM) methods were used for the first time to elucidate the external morphology of the European species of the genus Eulachnus (Hemiptera: Aphididae: Lachninae), a representative genus of the conifer-feeding aphids tribe Eulachnini. We examined and compared the external morphology of apterous and alate viviparous females from the parthenogenetic generation as well as oviparous females and alate males belonging to the sexual generation. FE-SEM images based on HMDS and cryo-SEM preparation techniques revealed better image quality than the CPD technique in regard to surface tension and morphological signs of cell deteriorations (i.e., existence of depressions, drying artifacts and membrane blebs). Three morphologically different species groups "agilis", "brevipilosus" and "cembrae" were proposed due to the differences in head, antennae, legs and dorsal chaetotaxy as well as dorsal sclerotization. The most characteristic features and differences of representatives of these groups are presented and discussed. Copyright © 2015 Elsevier Ltd. All rights reserved.

Structural equation modeling for observational studies

USGS Publications Warehouse

Grace, J.B.

2008-01-01

Structural equation modeling (SEM) represents a framework for developing and evaluating complex hypotheses about systems. This method of data analysis differs from conventional univariate and multivariate approaches familiar to most biologists in several ways. First, SEMs are multiequational and capable of representing a wide array of complex hypotheses about how system components interrelate. Second, models are typically developed based on theoretical knowledge and designed to represent competing hypotheses about the processes responsible for data structure. Third, SEM is conceptually based on the analysis of covariance relations. Most commonly, solutions are obtained using maximum-likelihood solution procedures, although a variety of solution procedures are used, including Bayesian estimation. Numerous extensions give SEM a very high degree of flexibility in dealing with nonnormal data, categorical responses, latent variables, hierarchical structure, multigroup comparisons, nonlinearities, and other complicating factors. Structural equation modeling allows researchers to address a variety of questions about systems, such as how different processes work in concert, how the influences of perturbations cascade through systems, and about the relative importance of different influences. I present 2 example applications of SEM, one involving interactions among lynx (Lynx pardinus), mongooses (Herpestes ichneumon), and rabbits (Oryctolagus cuniculus), and the second involving anuran species richness. Many wildlife ecologists may find SEM useful for understanding how populations function within their environments. Along with the capability of the methodology comes a need for care in the proper application of SEM.

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.

The role of advanced reactive surface area characterization in improving predictions of mineral reaction rates

NASA Astrophysics Data System (ADS)

Beckingham, L. E.; Zhang, S.; Mitnick, E.; Cole, D. R.; Yang, L.; Anovitz, L. M.; Sheets, J.; Swift, A.; Kneafsey, T. J.; Landrot, G.; Mito, S.; Xue, Z.; Steefel, C. I.; DePaolo, D. J.; Ajo Franklin, J. B.

2014-12-01

Geologic sequestration of CO2 in deep sedimentary formations is a promising means of mitigating carbon emissions from coal-fired power plants but the long-term fate of injected CO2 is challenging to predict. Reactive transport models are used to gain insight over long times but rely on laboratory determined mineral reaction rates that have been difficult to extrapolate to field systems. This, in part, is due to a lack of understanding of mineral reactive surface area. Many models use an arbitrary approximation of reactive surface area, applying orders of magnitude scaling factors to measured BET or geometric surface areas. Recently, a few more sophisticated approaches have used 2D and 3D image analyses to determine mineral-specific reactive surface areas that account for the accessibility of minerals. However, the ability of these advanced surface area estimates to improve predictions of mineral reaction rates has yet to be determined. In this study, we fuse X-ray microCT, SEM QEMSCAN, XRD, SANS, and SEM-FIB analysis to determine mineral-specific accessible reactive surface areas for a core sample from the Nagaoka pilot CO2 injection site (Japan). This sample is primarily quartz, plagioclase, smectite, K-feldspar, and pyroxene. SEM imaging shows abundant smectite cement and grain coatings that decrease the fluid accessibility of other minerals. However, analysis of FIB-SEM images reveals that smectite nano-pores are well connected such that access to underlying minerals is not occluded by smectite coatings. Mineral-specific accessible surfaces are determined, accounting for the connectivity of the pore space with and without connected smectite nano-pores. The large-scale impact of variations in accessibility and dissolution rates are then determined through continuum scale modeling using grid-cell specific information on accessible surface areas. This approach will be compared with a traditional continuum scale model using mineral abundances and common surface area estimates. Ultimately, the effectiveness of advanced surface area characterization to improve mineral dissolution rates will be evaluated by comparison of model results with dissolution rates measured from a flow-through column experiment.

Three-dimensional profile extraction from CD-SEM image and top/bottom CD measurement by line-edge roughness analysis

NASA Astrophysics Data System (ADS)

Yamaguchi, Atsuko; Ohashi, Takeyoshi; Kawasaki, Takahiro; Inoue, Osamu; Kawada, Hiroki

2013-04-01

A new method for calculating critical dimension (CDs) at the top and bottom of three-dimensional (3D) pattern profiles from a critical-dimension scanning electron microscope (CD-SEM) image, called as "T-sigma method", is proposed and evaluated. Without preparing a library of database in advance, T-sigma can estimate a feature of a pattern sidewall. Furthermore, it supplies the optimum edge-definition (i.e., threshold level for determining edge position from a CDSEM signal) to detect the top and bottom of the pattern. This method consists of three steps. First, two components of line-edge roughness (LER); noise-induced bias (i.e., LER bias) and unbiased component (i.e., bias-free LER) are calculated with set threshold level. Second, these components are calculated with various threshold values, and the threshold-dependence of these two components, "T-sigma graph", is obtained. Finally, the optimum threshold value for the top and the bottom edge detection are given by the analysis of T-sigma graph. T-sigma was applied to CD-SEM images of three kinds of resist-pattern samples. In addition, reference metrology was performed with atomic force microscope (AFM) and scanning transmission electron microscope (STEM). Sensitivity of CD measured by T-sigma to the reference CD was higher than or equal to that measured by the conventional edge definition. Regarding the absolute measurement accuracy, T-sigma showed better results than the conventional definition. Furthermore, T-sigma graphs were calculated from CD-SEM images of two kinds of resist samples and compared with corresponding STEM observation results. Both bias-free LER and LER bias increased as the detected edge point moved from the bottom to the top of the pattern in the case that the pattern had a straight sidewall and a round top. On the other hand, they were almost constant in the case that the pattern had a re-entrant profile. T-sigma will be able to reveal a re-entrant feature. From these results, it is found that T-sigma method can provide rough cross-sectional pattern features and achieve quick, easy and accurate measurements of top and bottom CD.

Nail Damage (Severe Onychodystrophy) Induced by Acrylate Glue: Scanning Electron Microscopy and Energy Dispersive X-Ray Investigations

PubMed Central

Pinteala, Tudor; Chiriac, Anca Eduard; Rosca, Irina; Larese Filon, Francesca; Pinteala, Mariana; Chiriac, Anca; Podoleanu, Cristian; Stolnicu, Simona; Coros, Marius Florin; Coroaba, Adina

2017-01-01

Background Scanning electron microscopy (SEM) and energy dispersive X-ray (EDX) techniques have been used in various fields of medical research, including different pathologies of the nails; however, no studies have focused on obtaining high-resolution microscopic images and elemental analysis of disorders caused by synthetic nails and acrylic adhesives. Methods Damaged/injured fingernails caused by the use of acrylate glue and synthetic nails were investigated using SEM and EDX methods. Results SEM and EDX proved that synthetic nails, acrylic glue, and nails damaged by contact with acrylate glue have a different morphology and different composition compared to healthy human nails. Conclusions SEM and EDX analysis can give useful information about the aspects of topography (surface sample), morphology (shape and size), hardness or reflectivity, and the elemental composition of nails. PMID:28232921

Standardization and quality control parameters for Muktā Bhasma (calcined pearl)

PubMed Central

Joshi, Namrata; Sharma, Khemchand; Peter, Hema; Dash, Manoj Kumar

2015-01-01

Background: Muktā Bhasma (MB) is a traditional Ayurvedic preparation for cough, breathlessness, and eye disorders and is a powerful cardiac tonic, mood elevator, and known to promote strength, intellect, and semen production. Objectives: The present research work was conducted to generate fingerprint for raw and processed MB for quality assessment and standardization using classical and other techniques. Setting and Design: Three samples of MB were prepared by purification (śodhana) of Muktā (pearl) followed by repeated calcinations (Māraṇa). Resultant product was subjected to organoleptic tests and Ayurvedic tests for quality control such as rekhāpūrṇatā, vāritaratva, and nirdhūmatva. Materials and Methods: For quality control, physicochemical parameters such as loss on drying, total ash value, acid insoluble ash, specific gravity, pH value, and other tests using techniques such as elemental analysis with energy dispersive X-ray analysis (EDAX), Structural study with powder X-ray diffraction, particle size with scanning electron microscopy (SEM) were carried out on raw Muktā, Śodhita Muktā, and triplicate batches of MB. Results: The study showed that the raw material Muktā was calcium carbonate in aragonite form, which on repeated calcinations was converted into a more stable calcite form. SEM studies revealed that in raw and purified materials the particles were found scattered and unevenly arranged in the range of 718.7–214.7 nm while in final product, uniformly arranged, stable, rod-shaped, and rounded particles with more agglomerates were observed in the range of 279.2–79.93 nm. EDAX analysis revealed calcium as a major ingredient in MB (average 46.32%) which increased gradually in the stages of processing (raw 34.11%, Śodhita 37.5%). Conclusion: Quality control parameters have been quantified for fingerprinting of MB prepared using a particular method. PMID:26600667

3D-printing zirconia implants; a dream or a reality? An in-vitro study evaluating the dimensional accuracy, surface topography and mechanical properties of printed zirconia implant and discs.

PubMed

Osman, Reham B; van der Veen, Albert J; Huiberts, Dennis; Wismeijer, Daniel; Alharbi, Nawal

2017-11-01

The aim of this study was to evaluate the dimensional accuracy, surface topography of a custom designed, 3D-printed zirconia dental implant and the mechanical properties of printed zirconia discs. A custom designed implant was 3D-printed in zirconia using digital light processing technique (DLP). The dimensional accuracy was assessed using the digital-subtraction technique. The mechanical properties were evaluated using biaxial flexure strength test. Three different build angles were adopted to print the specimens for the mechanical test; 0°(Vertical), 45° (Oblique) and 90°(Horizontal) angles. The surface topography, crystallographic phase structure and surface roughness were evaluated using scanning electron microscopy analysis (SEM), X-ray diffractometer and confocal microscopy respectively. The printed implant was dimensionally accurate with a root mean square (RMSE) value of 0.1mm. The Weibull analysis revealed a statistically significant higher characteristic strength (1006.6MPa) of 0° printed specimens compared to the other two groups and no significant difference between 45° (892.2MPa) and 90° (866.7MPa) build angles. SEM analysis revealed cracks, micro-porosities and interconnected pores ranging in size from 196nm to 3.3µm. The mean Ra (arithmetic mean roughness) value of 1.59µm (±0.41) and Rq (root mean squared roughness) value of 1.94µm (±0.47) was found. A crystallographic phase of primarily tetragonal zirconia typical of sintered Yttria tetragonal stabilized zirconia (Y-TZP) was detected. DLP prove to be efficient for printing customized zirconia dental implants with sufficient dimensional accuracy. The mechanical properties showed flexure strength close to those of conventionally produced ceramics. Optimization of the 3D-printing process parameters is still needed to improve the microstructure of the printed objects. Copyright © 2017 Elsevier Ltd. All rights reserved.

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

Bekar, Kursat B; Miller, Thomas Martin; Patton, Bruce W

The characteristic X-rays produced by the interactions of the electron beam with the sample in a scanning electron microscope (SEM) are usually captured with a variable-energy detector, a process termed energy dispersive spectrometry (EDS). The purpose of this work is to exploit inverse simulations of SEM-EDS spectra to enable rapid determination of sample properties, particularly elemental composition. This is accomplished using penORNL, a modified version of PENELOPE, and a modified version of the traditional Levenberg Marquardt nonlinear optimization algorithm, which together is referred to as MOZAIK-SEM. The overall conclusion of this work is that MOZAIK-SEM is a promising method formore » performing inverse analysis of X-ray spectra generated within a SEM. As this methodology exists now, MOZAIK-SEM has been shown to calculate the elemental composition of an unknown sample within a few percent of the actual composition.« less

X-ray diffraction, FTIR, UV-VIS and SEM studies on chromium (III) complexes

NASA Astrophysics Data System (ADS)

Mishra, Ashutosh; Dwivedi, Jagrati; Shukla, Kritika

2015-06-01

Five Chromium (III) complexes have been prepared using Schiff base ligands which derived from benzoin and five different amino acids (H2N-R). Samples were characterized by XRD, FTIR, UV-VIS and SEM method. X-Ray diffraction pattern analyzed that all chromium (III) complexes have hexagonal structure and crystalline, in nature, using Bruker D8 Advance instrument. Using VERTAX 70, FTIR spectroscopy reveals that Samples have (C=N), (C-O), (M-N) and (M-O) bonds in the range of 4000-400cm-1. UV-VIS spectroscopy give information that samples absorb the visible light which is in the range of 380-780nm. For this, Lambda 960 spectrometer used. SEM is designed for studying of the solid objects, using JEOL JSM 5600 instrument.

Miniature Variable Pressure Scanning Electron Microscope for In-Situ Imaging and Chemical Analysis

NASA Technical Reports Server (NTRS)

Gaskin, Jessica A.; Jerman, Gregory; Gregory, Don; Sampson, Allen R.

2012-01-01

NASA Marshall Space Flight Center (MSFC) is leading an effort to develop a Miniaturized Variable Pressure Scanning Electron Microscope (MVP-SEM) for in-situ imaging and chemical analysis of uncoated samples. This instrument development will be geared towards operation on Mars and builds on a previous MSFC design of a mini-SEM for the moon (funded through the NASA Planetary Instrument Definition and Development Program). Because Mars has a dramatically different environment than the moon, modifications to the MSFC lunar mini-SEM are necessary. Mainly, the higher atmospheric pressure calls for the use of an electron gun that can operate at High Vacuum, rather than Ultra-High Vacuum. The presence of a CO2-rich atmosphere also allows for the incorporation of a variable pressure system that enables the in-situ analysis of nonconductive geological specimens. Preliminary testing of Mars meteorites in a commercial Environmental SEM(Tradmark) (FEI) confirms the usefulness of lowcurrent/low-accelerating voltage imaging and highlights the advantages of using the Mars atmosphere for environmental imaging. The unique capabilities of the MVP-SEM make it an ideal tool for pursuing key scientific goals of NASA's Flagship Mission Max-C; to perform in-situ science and collect and cache samples in preparation for sample return from Mars.

New insights into micro/nanoscale combined probes (nanoAuger, μXPS) to characterize Ag/Au@SiO2 core-shell assemblies

NASA Astrophysics Data System (ADS)

Ledeuil, J. B.; Uhart, A.; Soulé, S.; Allouche, J.; Dupin, J. C.; Martinez, H.

2014-09-01

This work has examined the elemental distribution and local morphology at the nanoscale of core@shell Ag/Au@SiO2 particles. The characterization of such complex metal/insulator materials becomes more efficient when using an initial cross-section method of preparation of the core@shell nanoparticles (ion milling cross polisher). The originality of this route of preparation allows one to obtain undamaged, well-defined and planar layers of cross-cut nano-objects. Once combined with high-resolution techniques of characterization (XPS, Auger and SEM), the process appears as a powerful way to minimize charging effects and enhance the outcoming electron signal (potentially affected by the topography of the material) during analysis. SEM experiments have unambiguously revealed the hollow-morphology of the metal core, while Auger spectroscopy observations showed chemical heterogeneity within the particles (as silver and gold are randomly found in the core ring). To our knowledge, this is the first time that Auger nano probe spectroscopy has been used and successfully optimized for the study of some complex metal/inorganic interfaces at such a high degree of resolution (~12 nm). Complementarily, XPS Au 4f and Ag 3d peaks were finally detected attesting the possibility of access to the whole chemistry of such nanostructured assemblies.This work has examined the elemental distribution and local morphology at the nanoscale of core@shell Ag/Au@SiO2 particles. The characterization of such complex metal/insulator materials becomes more efficient when using an initial cross-section method of preparation of the core@shell nanoparticles (ion milling cross polisher). The originality of this route of preparation allows one to obtain undamaged, well-defined and planar layers of cross-cut nano-objects. Once combined with high-resolution techniques of characterization (XPS, Auger and SEM), the process appears as a powerful way to minimize charging effects and enhance the outcoming electron signal (potentially affected by the topography of the material) during analysis. SEM experiments have unambiguously revealed the hollow-morphology of the metal core, while Auger spectroscopy observations showed chemical heterogeneity within the particles (as silver and gold are randomly found in the core ring). To our knowledge, this is the first time that Auger nano probe spectroscopy has been used and successfully optimized for the study of some complex metal/inorganic interfaces at such a high degree of resolution (~12 nm). Complementarily, XPS Au 4f and Ag 3d peaks were finally detected attesting the possibility of access to the whole chemistry of such nanostructured assemblies. Electronic supplementary information (ESI) available. See DOI: 10.1039/c4nr03211j

Carbide-derived carbon (CDC) linear actuator properties in combination with conducting polymers

NASA Astrophysics Data System (ADS)

Kiefer, Rudolf; Aydemir, Nihan; Torop, Janno; Kilmartin, Paul A.; Tamm, Tarmo; Kaasik, Friedrich; Kesküla, Arko; Travas-Sejdic, Jadranka; Aabloo, Alvo

2014-03-01

Carbide-derived Carbon (CDC) material is applied for super capacitors due to their nanoporous structure and their high charging/discharging capability. In this work we report for the first time CDC linear actuators and CDC combined with polypyrrole (CDC-PPy) in ECMD (Electrochemomechanical deformation) under isotonic (constant force) and isometric (constant length) measurements in aqueous electrolyte. CDC-PPy actuators showing nearly double strain under cyclic voltammetric and square wave potential measurements in comparison to CDC linear actuators. The new material is investigated by SEM (scanning electron microscopy) and EDX (energy dispersive X-ray analysis) to reveal how the conducting polymer layer and the CDC layer interfere together.

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.

Spray deposited gallium doped tin oxide thinfilm for acetone sensor application

NASA Astrophysics Data System (ADS)

Preethi, M. S.; Bharath, S. P.; Bangera, Kasturi V.

2018-04-01

Undoped and gallium doped (1 at.%, 2 at.% and 3 at.%) tin oxide thin films were prepared using spray pyrolysis technique by optimising the deposition conditions such as precursor concentration, substrate temperature and spraying rate. X-ray diffraction analysis revealed formation of tetragonally structured polycrystalline films. The SEM micrographs of Ga doped films showed microstructures. The electrical resistivity of the doped films was found to be more than that of the undoped films. The Ga-doped tin oxide thin films were characterised for gas sensors. 1 at.% Ga doped thin films were found to be better acetone gas sensor, showed 68% sensitivity at 350°C temperature.

Investigations of the historic textiles excavated from Ancient Ainos (Enez - Turkey) by multiple analytical techniques

NASA Astrophysics Data System (ADS)

Akyuz, Sevim; Akyuz, Tanil; Cakan, Banu; Basaran, Sait

2014-09-01

Some metal ornamented textile specimens and a textile button, excavated from Ancient Ainos (Enez - Turkey), have been investigated using FTIR and EDXRF spectrometry, for the purpose of material identification. FTIR spectral results indicated that textiles were made from partially degummed Bombyx mori silk. The IR spectral investigation of the textile button revealed that some cellulose fillings were used inside the button. The EDXRF analysis of the metal ornaments showed that they were silver plated copper. Surface morphology of the textiles and the metal ornaments were investigated by SEM images. It was shown that textile fibers were highly degraded.

Assessing the utility of FIB-SEM images for shale digital rock physics

NASA Astrophysics Data System (ADS)

Kelly, Shaina; El-Sobky, Hesham; Torres-Verdín, Carlos; Balhoff, Matthew T.

2016-09-01

Shales and other unconventional or low permeability (tight) reservoirs house vast quantities of hydrocarbons, often demonstrate considerable water uptake, and are potential repositories for fluid sequestration. The pore-scale topology and fluid transport mechanisms within these nanoporous sedimentary rocks remain to be fully understood. Image-informed pore-scale models are useful tools for studying porous media: a debated question in shale pore-scale petrophysics is whether there is a representative elementary volume (REV) for shale models? Furthermore, if an REV exists, how does it differ among petrophysical properties? We obtain three dimensional (3D) models of the topology of microscale shale volumes from image analysis of focused ion beam-scanning electron microscope (FIB-SEM) image stacks and investigate the utility of these models as a potential REV for shale. The scope of data used in this work includes multiple local groups of neighboring FIB-SEM images of different microscale sizes, corresponding core-scale (milli- and centimeters) laboratory data, and, for comparison, series of two-dimensional (2D) cross sections from broad ion beam SEM images (BIB-SEM), which capture a larger microscale field of view than the FIB-SEM images; this array of data is larger than the majority of investigations with FIB-SEM-derived microscale models of shale. Properties such as porosity, organic matter content, and pore connectivity are extracted from each model. Assessments of permeability with single phase, pressure-driven flow simulations are performed in the connected pore space of the models using the lattice-Boltzmann method. Calculated petrophysical properties are compared to those of neighboring FIB-SEM images and to core-scale measurements of the sample associated with the FIB-SEM sites. Results indicate that FIB-SEM images below ∼5000 μm3 volume (the largest volume analyzed) are not a suitable REV for shale permeability and pore-scale networks; i.e. field of view is compromised at the expense of detailed, but often unconnected, nanopore morphology. Further, we find that it is necessary to acquire several local FIB-SEM or BIB-SEM images and correlate their extracted geometric properties to improve the likelihood of achieving representative values of porosity and organic matter volume. Our work indicates that FIB-SEM images of microscale volumes of shale are a qualitative tool for petrophysical and transport analysis. Finally, we offer alternatives for quantitative pore-scale assessments of shale.

An overview of structural equation modeling: its beginnings, historical development, usefulness and controversies in the social sciences.

PubMed

Tarka, Piotr

2018-01-01

This paper is a tribute to researchers who have significantly contributed to improving and advancing structural equation modeling (SEM). It is, therefore, a brief overview of SEM and presents its beginnings, historical development, its usefulness in the social sciences and the statistical and philosophical (theoretical) controversies which have often appeared in the literature pertaining to SEM. Having described the essence of SEM in the context of causal analysis, the author discusses the years of the development of structural modeling as the consequence of many researchers' systematically growing needs (in particular in the social sciences) who strove to effectively understand the structure and interactions of latent phenomena. The early beginnings of SEM models were related to the work of Spearman and Wright, and to that of other prominent researchers who contributed to SEM development. The importance and predominance of theoretical assumptions over technical issues for the successful construction of SEM models are also described. Then, controversies regarding the use of SEM in the social sciences are presented. Finally, the opportunities and threats of this type of analytical strategy as well as selected areas of SEM applications in the social sciences are discussed.

Synthesis, characterization, microstructure, optical and magnetic properties of strontium cobalt carbonate precursor and Sr2Co2O5 oxide material

NASA Astrophysics Data System (ADS)

Agilandeswari, K.; Ruban Kumar, A.

2014-04-01

Sr2Co2O5 ceramic synthesized by the coprecipitation of strontium cobalt carbonate method. XRD analysis shows the single phase strontianite precursor and decomposed oxide product as orthorhombic structure of Sr2Co2O5. Thermal analysis proves the Sr2Co2O5 phase formation temperature of 800 °C. SEM image indicates crystalline rod shaped carbonate precursor transformed to oxide as porous diffused sphere shape particles. Optical band gap it reveals the strontium cobalt carbonate precursor as insulating material and the Sr2Co2O5 as semiconducting nature. The room temperature magnetic study indicates the carbonate precursor as paramagnetic but its oxide Sr2Co2O5 as superparamagnetic behavior.

EPA Region 2 SEMS_CERCLIS Sites All [R2] and SEMS_CERCLIS Sites NPL [R2] GIS Layers

EPA Pesticide Factsheets

The Region 2 SEMS_CERCLIS Sites All [R2] GIS layer contains unique Superfund Enterprise Management System (SEMS) site records. These records have the following NPL_STATUS designations: CURRENTLY ON FINAL NPL, DELETED FROM FINAL NPL, NOT ON NPL, PROPOSED FOR NPL, REMOVED FROM PROPOSED NPL, and SITE IS PART OF NPL SITE. The Region 2 SEMS_CERCLIS NPL Sites [R2] GIS layer only has SEMS records with the following NPL_STATUS designations: 'CURRENTLY ON FINAL NPL', 'DELETED FROM FINAL NPL', 'PROPOSED FOR NPL'.The Superfund Enterprise Management System (SEMS) is EPA's official record for tracking hazardous waste sites, potentially hazardous waste sites, and remedial activities performed in support of the Superfund Program across the nation. This includes sites that are on the National Priorities List (NPL) or are being considered for the NPL. SEMS represents a joint development and ongoing collaboration between Superfund's Remedial, Removal, Federal Facilities, Enforcement, and Emergency Response programs. It provides its wide audience base with a means of ongoing analysis of Superfund Program activities and informational needs at the site, regional management, and national management levels. The customers of SEMS or SEMS data are five EPA Headquarters offices and regional staff, citizens, the regulated community, other Federal agencies, States, Tribes, local agencies, and industry. SEMS stakeholders are States, Congress, other Federal agencies, industry groups, and cit

Acceptability of Sexually Explicit Images in HIV Prevention Messages Targeting Men Who Have Sex With Men.

PubMed

Iantaffi, Alex; Wilkerson, J Michael; Grey, Jeremy A; Rosser, B R Simon

2015-01-01

Sexually explicit media (SEM) have been used in HIV-prevention advertisements to engage men who have sex with men (MSM) and to communicate content. These advertisements exist within larger discourses, including a dominant heteronormative culture and a growing homonormative culture. Cognizant of these hegemonic cultures, this analysis examined the acceptable level of sexual explicitness in prevention advertisements. Seventy-nine MSM participated in 13 online focus groups, which were part of a larger study of SEM. Three macro themes-audience, location, and community representation-emerged from the analysis, as did the influence of homonormativity on the acceptability of SEM in HIV-prevention messages.

Automated SEM-EDS GSR Analysis for Turkish Ammunitions

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

Cakir, Ismail; Uner, H. Bulent

2007-04-23

In this work, Automated Scanning Electron Microscopy with Energy Dispersive X-ray Spectrometry (SEM-EDS) was used to characterize 7.65 and 9mm cartridges Turkish ammunition. All samples were analyzed in a SEM Jeol JSM-5600LV equipped BSE detector and a Link ISIS 300 (EDS). A working distance of 20mm, an accelerating voltage of 20 keV and gunshot residue software was used in all analysis. Automated search resulted in a high number of particles analyzed containing gunshot residues (GSR) unique elements (PbBaSb). The obtained data about the definition of characteristic GSR particles was concordant with other studies on this topic.

Acceptability of Sexually Explicit Images in HIV Prevention Messages Targeting Men Who Have Sex with Men

PubMed Central

Iantaffi, Alex; Wilkerson, J. Michael; Grey, Jeremy A.; Rosser, B. R. Simon

2014-01-01

Sexually explicit media (SEM) have been used in HIV-prevention advertisements to engage men who have sex with men (MSM), and to communicate content. These advertisements exist within larger discourses, including a dominant heternormative culture, and a growing homonormative culture. Cognizant of these hegemonic cultures, this analysis examined the acceptable level of sexual explicitness in prevention advertisements. 79 MSM participated in 13 online focus groups, which were part of a larger study of SEM. Three macro-themes—audience, location and community representation—emerged from the analysis, as did the influence of homonormativity on the acceptability of SEM in HIV-prevention messages. PMID:26075485

Oral mucosa tissue response to titanium cover screws.

PubMed

Olmedo, Daniel G; Paparella, María L; Spielberg, Martín; Brandizzi, Daniel; Guglielmotti, María B; Cabrini, Rómulo L

2012-08-01

Titanium is the most widely used metal in dental implantology. The release of particles from metal structures into the biologic milieu may be the result of electrochemical processes (corrosion) and/or mechanical disruption during insertion, abutment connection, or removal of failing implants. The aim of the present study is to evaluate tissue response of human oral mucosa adjacent to titanium cover screws. One hundred fifty-three biopsies of the supra-implant oral mucosa adjacent to the cover screw of submerged dental implants were analyzed. Histologic studies were performed to analyze epithelial and connective tissue as well as the presence of metal particles, which were identified using microchemical analysis. Langerhans cells, macrophages, and T lymphocytes were studied using immunohistochemical techniques. The surface of the cover screws was evaluated by scanning electron microscopy (SEM). Forty-one percent of mucosa biopsies exhibited metal particles in different layers of the section thickness. Particle number and size varied greatly among specimens. Immunohistochemical study confirmed the presence of macrophages and T lymphocytes associated with the metal particles. Microchemical analysis revealed the presence of titanium in the particles. On SEM analysis, the surface of the screws exhibited depressions and irregularities. The biologic effects seen in the mucosa in contact with the cover screws might be associated with the presence of titanium or other elements, such as aluminum or vanadium. The potential long-term biologic effects of particles on soft tissues adjacent to metallic devices should be further investigated because these effects might affect the clinical outcome of the implant.

Synthesis, characterization and effect of calcination temperature on phase transformation and photocatalytic activity of Cu,S-codoped TiO 2 nanoparticles

NASA Astrophysics Data System (ADS)

Hamadanian, M.; Reisi-Vanani, A.; Majedi, A.

2010-01-01

A novel copper and sulfur codoped TiO 2 photocatalyst was synthesized by modified sol-gel method using titanium(IV) isopropoxide, CuCl 2·2H 2O and thiourea as precursors. The samples were characterized by X-ray diffraction (XRD), diffuse reflectance spectroscopy (DRS), scanning electron microscopy equipped with energy dispersive X-ray micro-analysis (SEM-EDX), transmission electron microscopy (TEM) and Fourier transform infrared (FT-IR) analysis. The XRD results showed undoped and Cu,S-codoped TiO 2 nanoparticles only include anatase phase. Effect of calcination temperature showed rutile phase appears in 650 and 700 °C for undoped and 0.1% Cu,S-codoped TiO 2, respectively. The SEM analysis revealed the doping of Cu and S does not leave any change in morphology of the catalyst surface. The increase of copper doping enhanced "red-shift" in the UV-vis absorption spectra. The TEM images confirmed the dopants suppressed the growth of TiO 2 grains. The photocatalytic activity of samples was tested for degradation of methyl orange (MO) solutions. The results showed photocatalytic activity of the catalysts with 0.05% Cu,0.05% S and 0.1% Cu,0.05% S were higher than that of other catalysts under ultraviolet (UV) and visible irradiation, respectively. Because of synergetic effect of S and Cu, the Cu,S-codoped TiO 2 catalyst has higher activity than undoped and Cu or S doped TiO 2 catalysts.

Metallurgical characterization of orthodontic brackets produced by Metal Injection Molding (MIM).

PubMed

Zinelis, Spiros; Annousaki, Olga; Makou, Margarita; Eliades, Theodore

2005-11-01

The aim of this study was to investigate the bonding base surface morphology, alloy type, microstructure, and hardness of four types of orthodontic brackets produced by Metal Injection Molding technology (Discovery, Extremo, Freedom, and Topic). The bonding base morphology of the brackets was evaluated by scanning electron microscopy (SEM). Brackets from each manufacturer were embedded in epoxy resin, and after metallographic grinding, polishing and coating were analyzed by x-ray energy-dispersive spectroscopic (EDS) microanalysis to assess their elemental composition. Then, the brackets were subjected to metallographic etching to reveal their metallurgical structure. The same specimen surfaces were repolished and used for Vickers microhardness measurements. The results were statistically analyzed with one-way analysis of variance and Student-Newman-Keuls multiple comparison test at the 0.05 level of significance. The findings of SEM observations showed a great variability in the base morphology design among the brackets tested. The x-ray EDS analysis demonstrated that each bracket was manufactured from different ferrous or Co-based alloys. Metallographic analysis showed the presence of a large grain size for the Discovery, Freedom, and Topic brackets and a much finer grain size for the Extremo bracket. Vickers hardness showed great variations among the brackets (Topic: 287 +/- 16, Freedom: 248 +/- 13, Discovery: 214 +/- 12, and Extremo: 154 +/- 9). The results of this study showed that there are significant differences in the base morphology, composition, microstructure, and microhardness among the brackets tested, which may anticipate significant clinical implications.

A study on structure, morphology, optical properties, and photocatalytic ability of SrTiO3/TiO2 granular composites

NASA Astrophysics Data System (ADS)

Thi Mai Oanh, Le; Xuan Huy, Nguyen; Thi Thuy Phuong, Doan; Danh Bich, Do; Van Minh, Nguyen

2018-03-01

(1-x)SrTiO3-xTiO2 granular composites with x=0.3, 0.4, 0.5, 0.6, 0.7, and 0.8 were synthesized by sol-gel process. Structure, morphology, optical properties, and photocatalytic activity were investigated in detail using x-ray diffraction (XRD) analysis, Raman scattering, field-emission scanning electron microscopy (FE-SEM), Transmission Electron Microscopy (TEM), ultraviolet-visible (UV-vis) absorption spectra, and photoluminescence (PL). XRD analysis showed the formation of single phase for parent phases and the present of two component phases in all composites without any impurity. A tight cohesion between TiO2 and SrTiO3 (STO) at grain boundary region was inferred from lattice parameter change of STO. Moreover, FE-SEM images revealed a granular structure of composite in which SrTiO3 particles were surrounded by smaller TiO2 nanoparticles. As TiO2 concentration increased, absorption edge firstly shifted to the left for composite with x=0.3 and then shifted gradually to the right with further increasing of TiO2 content from 30 mol% to 80 mol%. Composites exhibited a stronger photocatalytic activity than parent phases, with the highest efficiency at 50 mol% of TiO2. PL analysis result showed that the recombination rate of photogenerated electron-hole pairs decreased in composite sample, which partly explained the enhanced photocatalytic property.

Achromobacter xylosoxidans as a new microorganism strain colonizing high-density polyethylene as a key step to its biodegradation.

PubMed

Kowalczyk, Anna; Chyc, Marek; Ryszka, Przemysław; Latowski, Dariusz

2016-06-01

This study presents results of research on isolation new bacteria strain Achromobacter xylosoxidans able to effect on the structure of high-density polyethylene (HDPE), polymer resistant to degradation in environment. New strain of A. xylosoxidans PE-1 was isolated from the soil and identified by analysis of the 16S ribosome subunit coding sequences. The substance to be degraded was HDPE in the form of thin foil films. The foil samples were analyzed with Attenuated Total Reflectance Fourier Transform Infrared Spectroscopy (ATR-FTIR) as well as scanning electron microscope (SEM), and the results revealed degradation of chemical structure of HDPE. About 9 % loss of weight was also detected as a result of A. xylosoxidans PE-1 effect on HDPE foil. On the basis of comparative spectral analysis of the raw material before the bacteria treatment and the spectrum from a spectra database, it was assumed that the HDPE was the only source of carbon and energy for the microorganisms. No fillers or other additives used in the plastic processing were observed in HDPE before experiments. This is the first communication showing that A. xylosoxidans is able to modify chemical structure of HDPE, what was observed both on FTIR, in mass reduction of HDPE and SEM analysis. We also observed quite good growth of the bacteria also when the HDPE was the sole carbon source in the medium. These results prove that A. xylosoxidans is an organism worth applying in future HDPE biodegradation studies.

Photoreactive, core-shell cross-linked/hollow microspheres prepared by delayed addition of cross-linker in dispersion polymerization for antifouling and immobilization of protein.

PubMed

Wang, Shengliu; Yue, Kai; Liu, Lianying; Yang, Wantai

2013-01-01

When dispersion polymerization of styrene (St) had run for 3h, after particle rapidly growing stage, 4,4'-dimethacryloyloxybenzophenone (DMABP) cross-linker was added to reaction system and photoreactive, core(PSt)-shell(Poly(St-co-DMABP)) particles with rich benzophenone (BP) groups on surface were prepared. Polymerization of DMABP could occurred mainly on the preformed core of PSt because its diffusion could be impeded by (1) compactness of particles formed at the moment of cross-linker addition (more than 80% of monomer had been consumed, particles were no longer fully swollen by monomer), (2) reduced polarity of continuous phase, and (3) immediate occurrence of cross-linking. Subsequently, photoreactive, cross-linked hollow particles were yielded by removal of uncross-linked core in THF. SEM and TEM observation demonstrated the formation of core-shell structure and improvement of shell thickness when DMABP content increased. UV-vis spectra analysis on polymer dissolved in THF indicated that there is no polymer of DMABP in core. FTIR spectra analysis and XPS measurement further revealed that BP component on particle surface was enriched when amount of DMABP increased. Finally, an anti-fouling polymer (poly (ethylene glycol), PEG) and protein of mouse IgG was immobilized on particle surface under UV irradiation, as confirmed by FTIR spectra analysis, SEM observation and TMB color reaction. Crown Copyright © 2012. Published by Elsevier Inc. All rights reserved.

Physicochemical and microscopic characterization of implant-abutment joints.

PubMed

Lopes, Patricia A; Carreiro, Adriana F P; Nascimento, Rubens M; Vahey, Brendan R; Henriques, Bruno; Souza, Júlio C M

2018-01-01

The purpose of this study was to investigate Morse taper implant-abutment joints by chemical, mechanical, and microscopic analysis. Surfaces of 10 Morse taper implants and the correlated abutments were inspected by field emission gun-scanning electron microscopy (FEG-SEM) before connection. The implant-abutment connections were tightened at 32 Ncm. For microgap evaluation by FEG-SEM, the systems were embedded in epoxy resin and cross-sectioned at a perpendicular plane of the implant-abutment joint. Furthermore, nanoindentation tests and chemical analysis were performed at the implant-abutment joints. Results were statistically analyzed via one-way analysis of variance, with a significance level of P < 0.05. Defects were noticed on different areas of the abutment surfaces. The minimum and maximum size of microgaps ranged from 0.5 μm up to 5.6 μm. Furthermore, defects were detected throughout the implant-abutment joint that can, ultimately, affect the microgap size after connection. Nanoindentation tests revealed a higher hardness (4.2 ± 0.4 GPa) for abutment composed of Ti6Al4V alloy when compared to implant composed of commercially pure Grade 4 titanium (3.2 ± 0.4 GPa). Surface defects produced during the machining of both implants and abutments can increase the size of microgaps and promote a misfit of implant-abutment joints. In addition, the mismatch in mechanical properties between abutment and implant can promote the wear of surfaces, affecting the size of microgaps and consequently the performance of the joints during mastication.

Cryo-FIB-SEM serial milling and block face imaging: Large volume structural analysis of biological tissues preserved close to their native state.

PubMed

Vidavsky, Netta; Akiva, Anat; Kaplan-Ashiri, Ifat; Rechav, Katya; Addadi, Lia; Weiner, Steve; Schertel, Andreas

2016-12-01

Many important biological questions can be addressed by studying in 3D large volumes of intact, cryo fixed hydrated tissues (⩾10,000μm 3 ) at high resolution (5-20nm). This can be achieved using serial FIB milling and block face surface imaging under cryo conditions. Here we demonstrate the unique potential of the cryo-FIB-SEM approach using two extensively studied model systems; sea urchin embryos and the tail fin of zebrafish larvae. We focus in particular on the environment of mineral deposition sites. The cellular organelles, including mitochondria, Golgi, ER, nuclei and nuclear pores are made visible by the image contrast created by differences in surface potential of different biochemical components. Auto segmentation and/or volume rendering of the image stacks and 3D reconstruction of the skeleton and the cellular environment, provides a detailed view of the relative distribution in space of the tissue/cellular components, and thus of their interactions. Simultaneous acquisition of secondary and back-scattered electron images adds additional information. For example, a serial view of the zebrafish tail reveals the presence of electron dense mineral particles inside mitochondrial networks extending more than 20μm in depth in the block. Large volume imaging using cryo FIB SEM, as demonstrated here, can contribute significantly to the understanding of the structures and functions of diverse biological tissues. Copyright © 2016 Elsevier Inc. All rights reserved.

Graft union formation in artichoke grafting onto wild and cultivated cardoon: an anatomical study.

PubMed

Trinchera, Alessandra; Pandozy, Gianmarco; Rinaldi, Simona; Crinò, Paola; Temperini, Olindo; Rea, Elvira

2013-12-15

In order to develop a non-chemical method such as grafting effective against well-known artichoke soil borne diseases, an anatomical study of union formation in artichoke grafted onto selected wild and cultivated cardoon rootstocks, both resistant to Verticillium wilt, was performed. The cardoon accessions Belgio (cultivated cardoon) and Sardo (wild cardoon) were selected as rootstocks for grafting combinations with the artichoke cv. Romolo. Grafting experiments were carried out in the autumn and spring. The anatomical investigation of grafting union formation was conducted by scanning electron microscopy (SEM) on the grafting portions at the 3rd, 6th, 10th, 12th day after grafting. For the autumn experiment only, SEM analysis was also performed at 30 d after grafting. A high affinity between artichoke scion and cardoon rootstocks was observed, with some genotype differences in healing time between the two bionts. SEM images of scion/rootstock longitudinal sections revealed the appearance of many interconnecting structures between the two grafting components just 3d after grafting, followed by a vascular rearrangement and a callus development during graft union formation. De novo formation of many plasmodesmata between scion and rootstock confirmed their high compatibility, particularly in the globe artichoke/wild cardoon combination. Moreover, the duration of the early-stage grafting process could be influenced not only by the scion/rootstock compatibility, but also by the seasonal conditions, being favored by lower temperatures and a reduced light/dark photoperiod. Copyright © 2013 Elsevier GmbH. All rights reserved.

Titanium Ions Release from an Innovative Titanium-Magnesium Composite: an in Vitro Study

PubMed Central

Halambek, Jasna; Maldini, Krešimir; Balog, Martin; Križik, Peter; Schauperl, Zdravko; Ćatić, Amir

2016-01-01

Background The innovative titanium-magnesium composite (Ti-Mg) was produced by powder metallurgy (P/M) method and is characterized in terms of corrosion behavior. Material and methods Two groups of experimental material, 1 mass% (Ti-1Mg) and 2 mass% (Ti-2Mg) of magnesium in titanium matrix, were tested and compared to commercially pure titanium (CP Ti). Immersion test and chemical analysis of four solutions: artificial saliva; artificial saliva pH 4; artificial saliva with fluoride and Hank balanced salt solution were performed after 42 days of immersion, using inductively coupled plasma mass spectrometry (ICP-MS) to detect the amount of released titanium ions (Ti). SEM and EDS analysis were used for surface characterization. Results The difference between the results from different test solutions was assessed by ANOVA and Newman-Keuls test at p<0.05. The influence of predictor variables was found by multiple regression analysis. The results of the present study revealed a low corrosion rate of titanium from the experimental Ti-Mg group. Up to 46 and 23 times lower dissolution of Ti from Ti-1Mg and Ti-2Mg, respectively was observed compared to the control group. Among the tested solutions, artificial saliva with fluorides exhibited the highest corrosion effect on all specimens tested. SEM micrographs showed preserved dual phase surface structure and EDS analysis suggested a favorable surface bioactivity. Conclusion In conclusion, Ti-Mg produced by P/M as a material with better corrosion properties when compared to CP Ti is suggested. PMID:27688425

Maternal risk factors predicting child physical characteristics and dysmorphology in fetal alcohol syndrome and partial fetal alcohol syndrome.

PubMed

May, Philip A; Tabachnick, Barbara G; Gossage, J Phillip; Kalberg, Wendy O; Marais, Anna-Susan; Robinson, Luther K; Manning, Melanie; Buckley, David; Hoyme, H Eugene

2011-12-01

Previous research in South Africa revealed very high rates of fetal alcohol syndrome (FAS), of 46-89 per 1000 among young children. Maternal and child data from studies in this community summarize the multiple predictors of FAS and partial fetal alcohol syndrome (PFAS). Sequential regression was employed to examine influences on child physical characteristics and dysmorphology from four categories of maternal traits: physical, demographic, childbearing, and drinking. Then, a structural equation model (SEM) was constructed to predict influences on child physical characteristics. Individual sequential regressions revealed that maternal drinking measures were the most powerful predictors of a child's physical anomalies (R² = .30, p < .001), followed by maternal demographics (R² = .24, p < .001), maternal physical characteristics (R²=.15, p < .001), and childbearing variables (R² = .06, p < .001). The SEM utilized both individual variables and the four composite categories of maternal traits to predict a set of child physical characteristics, including a total dysmorphology score. As predicted, drinking behavior is a relatively strong predictor of child physical characteristics (β = 0.61, p < .001), even when all other maternal risk variables are included; higher levels of drinking predict child physical anomalies. Overall, the SEM model explains 62% of the variance in child physical anomalies. As expected, drinking variables explain the most variance. But this highly controlled estimation of multiple effects also reveals a significant contribution played by maternal demographics and, to a lesser degree, maternal physical and childbearing variables. Copyright © 2011 Elsevier Ireland Ltd. All rights reserved.

SEM-EDX analysis of an unknown "known" white powder found in a shipping container from Peru

NASA Astrophysics Data System (ADS)

Albright, Douglas C.

2009-05-01

In 2008, an unknown white powder was discovered spilled inside of a shipping container of whole kernel corn during an inspection by federal inspectors in the port of Baltimore, Maryland. The container was detained and quarantined while a sample of the powder was collected and sent to a federal laboratory where it was screened using chromatography for the presence of specific poisons and pesticides with negative results. Samples of the corn kernels and the white powder were forwarded to the Food and Drug Administration, Forensic Chemistry Center for further analysis. Stereoscopic Light Microscopy (SLM), Scanning Electron Microscopy/Energy Dispersive X-ray Spectrometry (SEM/EDX), and Polarized Light Microscopy/Infrared Spectroscopy (PLM-IR) were used in the analysis of the kernels and the unknown powder. Based on the unique particle analysis by SLM and SEM as well as the detection of the presence of aluminum and phosphorous by EDX, the unknown was determined to be consistent with reacted aluminum phosphide (AlP). While commonly known in the agricultural industry, aluminum phosphide is relatively unknown in the forensic community. A history of the use and acute toxicity of this compound along with some very unique SEM/EDX analysis characteristics of aluminum phosphide will be discussed.

A versatile atomic force microscope integrated with a scanning electron microscope.

PubMed

Kreith, J; Strunz, T; Fantner, E J; Fantner, G E; Cordill, M J

2017-05-01

A versatile atomic force microscope (AFM), which can be installed in a scanning electron microscope (SEM), is introduced. The flexible design of the instrument enables correlated analysis for different experimental configurations, such as AFM imaging directly after nanoindentation in vacuum. In order to demonstrate the capabilities of the specially designed AFM installed inside a SEM, slip steps emanating around nanoindents in single crystalline brass were examined. This example showcases how the combination of AFM and SEM imaging can be utilized for quantitative dislocation analysis through the measurement of the slip step heights without the hindrance of oxide formation. Finally, an in situ nanoindentation technique is introduced, illustrating the use of AFM imaging during indentation experiments to examine plastic deformation occurring under the indenter tip. The mechanical indentation data are correlated to the SEM and AFM images to estimate the number of dislocations emitted to the surface.

Complications pertaining to the detection and characterization of individual and embedded single walled carbon nanotubes by scanning electron microscopy

NASA Astrophysics Data System (ADS)

Orbaek, Alvin W.; Barron, Andrew R.

2013-03-01

Comparison of AFM and SEM images of single walled carbon nanotubes (SWNTs) grown within a dielectric matrix reveal subterranean nanotubes that are present within the matrix, and as such can be charge screened by the dielectric. Under adequate imaging conditions for the SWNT/silica sample the intensity of isolated nanotubes is found to be inversely proportional to the instrument dwell time (i.e., shorter dwell times were found to make SWNT intensities brighter). The threshold dwell time required to enable isolated tubes to be visible was found to be 10 μs moreover, the degree change in intensity was found to be nanotube specific, i.e., different SWNTs respond in a different manner at different dwell times. The results indicate that care should be taken when attempting to quantify number density and length distributions of SWNTs on or within a dielectric matrix.Comparison of AFM and SEM images of single walled carbon nanotubes (SWNTs) grown within a dielectric matrix reveal subterranean nanotubes that are present within the matrix, and as such can be charge screened by the dielectric. Under adequate imaging conditions for the SWNT/silica sample the intensity of isolated nanotubes is found to be inversely proportional to the instrument dwell time (i.e., shorter dwell times were found to make SWNT intensities brighter). The threshold dwell time required to enable isolated tubes to be visible was found to be 10 μs moreover, the degree change in intensity was found to be nanotube specific, i.e., different SWNTs respond in a different manner at different dwell times. The results indicate that care should be taken when attempting to quantify number density and length distributions of SWNTs on or within a dielectric matrix. Electronic supplementary information (ESI) available: Plots of SEM for cross over points, raw SEM images used for Fig. 5, and Fig. 6, SEM image of scattering centre, and SEM images with various scan directions at 10 μs dwell time. See DOI: 10.1039/c3nr00142c

Staying on Task: Age-Related Changes in the Relationship Between Executive Functioning and Response Time Consistency.

PubMed

Vasquez, Brandon P; Binns, Malcolm A; Anderson, Nicole D

2016-03-01

Little is known about the relationship of executive functioning with age-related increases in response time (RT) distribution indices (intraindividual standard deviation [ISD], and ex-Gaussian parameters mu, sigma, tau). The goals of this study were to (a) replicate findings of age-related changes in response time distribution indices during an engaging touch-screen RT task and (b) investigate age-related changes in the relationship between executive functioning and RT distribution indices. Healthy adults (24 young [aged 18-30], 24 young-old [aged 65-74], and 24 old-old [aged 75-85]) completed a touch-screen attention task and a battery of neuropsychological tests. The relationships between RT performance and executive functions were examined with structural equation modeling (SEM). ISD, mu, and tau, but not sigma, increased with age. SEM revealed tau as the most salient RT index associated with neuropsychological measures of executive functioning. Further analysis demonstrated that correlations between tau and a weighted executive function composite were significant only in the old-old group. Our results replicate findings of greater RT inconsistency in older adults and reveal that executive functioning is related to tau in adults aged 75-85. These results support literature identifying tau as a marker of cognitive control, which deteriorates in old age. © The Author 2014. Published by Oxford University Press on behalf of The Gerontological Society of America. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

A test of self-determination theory in school physical education.

PubMed

Standage, Martyn; Duda, Joan L; Ntoumanis, Nikos

2005-09-01

Contemporary research conducted in the context of school physical education (PE) has increasingly embraced various tenets of self-determination theory (Deci & Ryan, 1985, 1991). Despite this increase in research attention, some postulates of the framework remain unexplored (e.g. impact of a need-supportive climate). As such, the present study sought to provide a more comprehensive test of self-determination theory. The present work also examined Deci and Ryan's claim that the motivational sequence embraced by their framework is invariant across gender. (i) To examine a model of motivation based on the tenets of self-determination theory, and (ii) explore the invariance of the model across gender. Participants were 950 British secondary school students (443 male, 490 female, 17 gender not specified) Participants completed a questionnaire that included measures of need support, need satisfaction, motivation, positive and negative affect, task challenge, and concentration. Structural equation modelling (SEM) analysis revealed that students who perceived a need-supporting environment experienced greater levels of need satisfaction. Need satisfaction predicted intrinsic motivation, which, in turn, linked to adaptive PE-related outcomes. In contrast, need satisfaction negatively predicted amotivation, which, in turn, was positively predictive of feelings of unhappiness. Multisample SEM invariance testing revealed the model to be largely invariant for male and female students. The results of the study provide support for self-determination theory and corroborate the application of the framework to the context of school PE. Further, we largely found support for the invariance of the motivational processes embraced by self-determination theory across gender.

Time-Resolved Study of Nanomorphology and Nanomechanic Change of Early-Stage Mineralized Electrospun Poly(lactic acid) Fiber by Scanning Electron Microscopy, Raman Spectroscopy and Atomic Force Microscopy

PubMed Central

Wang, Mengmeng; Cai, Yin; Zhao, Bo; Zhu, Peizhi

2017-01-01

In this study, scanning electron microscopy (SEM), Raman spectroscopy and high-resolution atomic force microscopy (AFM) were used to reveal the early-stage change of nanomorphology and nanomechanical properties of poly(lactic acid) (PLA) fibers in a time-resolved manner during the mineralization process. Electrospun PLA nanofibers were soaked in simulated body fluid (SBF) for different periods of time (0, 1, 3, 5, 7 and 21 days) at 10 °C, much lower than the conventional 37 °C, to simulate the slow biomineralization process. Time-resolved Raman spectroscopy analysis can confirm that apatites were deposited on PLA nanofibers after 21 days of mineralization. However, there is no significant signal change among several Raman spectra before 21 days. SEM images can reveal the mineral deposit on PLA nanofibers during the process of mineralization. In this work, for the first time, time-resolved AFM was used to monitor early-stage nanomorphology and nanomechanical changes of PLA nanofibers. The Surface Roughness and Young’s Modulus of the PLA nanofiber quantitatively increased with the time of mineralization. The electrospun PLA nanofibers with delicate porous structure could mimic the extracellular matrix (ECM) and serve as a model to study the early-stage mineralization. Tested by the mode of PLA nanofibers, we demonstrated that AFM technique could be developed as a potential diagnostic tool to monitor the early onset of pathologic mineralization of soft tissues. PMID:28817096

Software analysis in the semantic web

NASA Astrophysics Data System (ADS)

Taylor, Joshua; Hall, Robert T.

2013-05-01

Many approaches in software analysis, particularly dynamic malware analyis, benefit greatly from the use of linked data and other Semantic Web technology. In this paper, we describe AIS, Inc.'s Semantic Extractor (SemEx) component from the Malware Analysis and Attribution through Genetic Information (MAAGI) effort, funded under DARPA's Cyber Genome program. The SemEx generates OWL-based semantic models of high and low level behaviors in malware samples from system call traces generated by AIS's introspective hypervisor, IntroVirtTM. Within MAAGI, these semantic models were used by modules that cluster malware samples by functionality, and construct "genealogical" malware lineages. Herein, we describe the design, implementation, and use of the SemEx, as well as the C2DB, an OWL ontology used for representing software behavior and cyber-environments.

Endoscopic removal of malfunctioning biliary self-expandable metallic stents.

PubMed

Familiari, Pietro; Bulajic, Milutin; Mutignani, Massimiliano; Lee, Linda S; Spera, Gianluca; Spada, Cristiano; Tringali, Andrea; Costamagna, Guido

2005-12-01

Endoscopic removal of malfunctioning self-expandable metallic biliary stents (SEMS) is difficult and not well described. The aim of this study is to review the indications, the techniques, and the results of SEMS removal in a cohort of patients with malfunctioning stents. All patients who underwent an attempt at endoscopic removal of biliary SEMS over a 5-year period were retrospectively identified. The main indications for SEMS removal were the following: distal migration of the stent or impaction to the duodenum, impaction into the bile-duct wall, tissue ingrowth, and inappropriate length of the stent causing occlusion of intrahepatic ducts. SEMS were removed by using foreign-body forceps or polypectomy snares. Endoscopic removal of 39 SEMS (13 uncovered and 26 covered) was attempted in 29 patients (17 men; mean age, 66 years). SEMS extraction was attempted after a mean of 7.5 months (8.75 months standard deviation) post-SEMS insertion. Removal was successful in 20 patients (68.9%) and in 29 SEMS (74.3%). Covered SEMS were effectively removed more frequently than uncovered ones: 24 of 26 (92.3%) and 5 of 13 (38.4%), respectively (p < 0.05). No major complications were recorded. Multivariate analysis showed that the time interval between insertion and removal, SEMS length, stent-mesh design (zigzag vs. interlaced), and indication for removal were not predictive of success at stent removal. Endoscopic removal of biliary SEMS is feasible and safe in more than 70% of cases. Because only 38% of uncovered SEMS were removable, the presence of a stent covering is the only factor predictive of successful stent extraction. The presence of diffuse and severe ingrowth was the main feature limiting SEMS removal.

Synthesis and characterisation of the uranium pyrochlore betafite [(Ca,U)₂(Ti,Nb,Ta)₂O₇].

PubMed

McMaster, Scott A; Ram, Rahul; Charalambous, Fiona; Pownceby, Mark I; Tardio, James; Bhargava, Suresh K

2014-09-15

Betafite of composition [(Ca,U)2(Ti,Nb,Ta)2O7] was prepared via a solid state synthesis route. The synthesis was shown to be sensitive to initial reactant ratios, the atmosphere used (oxidising, neutral, reducing) and time. The optimum conditions for the synthesis of betafite were found to be heating the reactants required at 1150°C for 48 h under an inert gas atmosphere. XRD characterisation revealed that the synthesised betafite contained minor impurities. EPMA analysis of a sectioned surface showed very small regions of Ca-free betafite on grain boundaries as well as minor rutile impurities. Some heterogeneity between the Nb:Ta ratio was observed by quantitative EPMA but was generally within the nomenclature requirements stated for betafite. SEM analysis revealed the synthesised betafite was comprised mostly of hexaoctohedral crystals of ∼ 3 μm in diameter. XPS analysis of the sample showed that the uranium in the synthesised betafite was predominately present in the U(5+) oxidation state. A minor amount of U(6+) was also detected which was possibly due to surface oxidation. Copyright © 2014 Elsevier B.V. All rights reserved.

Spinal electro-magnetic stimulation combined with transgene delivery of neurotrophin NT-3 and exercise: novel combination therapy for spinal contusion injury

PubMed Central

Petrosyan, Hayk A.; Alessi, Valentina; Hunanyan, Arsen S.; Sisto, Sue A.

2015-01-01

Our recent terminal experiments revealed that administration of a single train of repetitive spinal electromagnetic stimulation (sEMS; 35 min) enhanced synaptic plasticity in spinal circuitry following lateral hemisection spinal cord injury. In the current study, we have examined effects of repetitive sEMS applied as a single train and chronically (5 wk, every other day) following thoracic T10 contusion. Chronic studies involved examination of systematic sEMS administration alone and combined with exercise training and transgene delivery of neurotrophin [adeno-associated virus 10-neurotrophin 3 (AAV10-NT3)]. Electrophysiological intracellular/extracellular recordings, immunohistochemistry, behavioral testing, and anatomical tracing were performed to assess effects of treatments. We found that administration of a single sEMS train induced transient facilitation of transmission through preserved lateral white matter to motoneurons and hindlimb muscles in chronically contused rats with effects lasting for at least 2 h. These physiological changes associated with increased immunoreactivity of GluR1 and GluR2/3 glutamate receptors in lumbar neurons. Systematic administration of sEMS alone for 5 wk, however, was unable to induce cumulative improvements of transmission in spinomuscular circuitry or improve impaired motor function following thoracic contusion. Encouragingly, chronic administration of sEMS, followed by exercise training (running in an exercise ball and swimming), induced the following: 1) sustained strengthening of transmission to lumbar motoneurons and hindlimb muscles, 2) better retrograde transport of anatomical tracer, and 3) improved locomotor function. Greatest improvements were seen in the group that received exercise combined with sEMS and AAV-NT3. PMID:26424579

Spinal electro-magnetic stimulation combined with transgene delivery of neurotrophin NT-3 and exercise: novel combination therapy for spinal contusion injury.

PubMed

Petrosyan, Hayk A; Alessi, Valentina; Hunanyan, Arsen S; Sisto, Sue A; Arvanian, Victor L

2015-11-01

Our recent terminal experiments revealed that administration of a single train of repetitive spinal electromagnetic stimulation (sEMS; 35 min) enhanced synaptic plasticity in spinal circuitry following lateral hemisection spinal cord injury. In the current study, we have examined effects of repetitive sEMS applied as a single train and chronically (5 wk, every other day) following thoracic T10 contusion. Chronic studies involved examination of systematic sEMS administration alone and combined with exercise training and transgene delivery of neurotrophin [adeno-associated virus 10-neurotrophin 3 (AAV10-NT3)]. Electrophysiological intracellular/extracellular recordings, immunohistochemistry, behavioral testing, and anatomical tracing were performed to assess effects of treatments. We found that administration of a single sEMS train induced transient facilitation of transmission through preserved lateral white matter to motoneurons and hindlimb muscles in chronically contused rats with effects lasting for at least 2 h. These physiological changes associated with increased immunoreactivity of GluR1 and GluR2/3 glutamate receptors in lumbar neurons. Systematic administration of sEMS alone for 5 wk, however, was unable to induce cumulative improvements of transmission in spinomuscular circuitry or improve impaired motor function following thoracic contusion. Encouragingly, chronic administration of sEMS, followed by exercise training (running in an exercise ball and swimming), induced the following: 1) sustained strengthening of transmission to lumbar motoneurons and hindlimb muscles, 2) better retrograde transport of anatomical tracer, and 3) improved locomotor function. Greatest improvements were seen in the group that received exercise combined with sEMS and AAV-NT3.

Synthesis, microstructure and dielectric properties of zirconium doped barium titanate

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

Kumar, Rohtash; School of Physical Sciences, Jawaharlal Nehru University, New Delhi; Asokan, K.

2016-05-23

We report on synthesis, microstructural and relaxor ferroelectric properties of Zirconium(Zr) doped Barium Titanate (BT) samples with general formula Ba(Ti{sub 1-x}Zr{sub x})O{sub 3} (x=0.20, 0.35). These lead-free ceramics were prepared by solid state reaction route. The phase transition behavior and temperature dependent dielectric properties and composition dependent ferroelectric properties were investigated. XRD analysis at room temperature confirms phase purity of the samples. SEM observations revealed retarded grain growth with increasing Zr mole fraction. Dielectric properties of BZT ceramics is influenced significantly by small addition of Zr mole fraction. With increasing Zr mole fraction, dielectric constant decreases while FWHM and frequencymore » dispersion increases. Polarization vs electric field hysteresis measurements reveal ferroelectric relaxor phase at room temperature. The advantages of such substitution maneuvering towards optimizing ferroelectric properties of BaTiO{sub 3} are discussed.« less

The Microstructure of RR1000 Nickel-Base Superalloy: The FIB-SEM Dual-Beam Approach

NASA Astrophysics Data System (ADS)

Croxall, S. A.; Hardy, M. C.; Stone, H. J.; Midgley, P. A.

Nickel-base superalloys are aerospace materials that exhibit exceptional mechanical properties and corrosion resistance at very high temperatures. RR1000 is used in discs in gas turbine engines, where temperatures reach in excess of 650°C with high mechanical stresses. Study of the microstructure at the micron and sub-micron level has conventionally been undertaken using scanning electron microscope images, often meaning the underlying 3D microstructure can be inferred only with additional knowledge. Using a dual-beam workstation, we are able to interrogate directly the 3D microstructure using a serial sectioning approach. The 3D data set, typically (10µm)3 in volume, reveals microstructural detail with lateral resolution of circa 8nm and a depth resolution dictated by the slice thickness, typically 50nm. Morphological and volumetric analysis of the 3D reconstruction of RR1000 superalloy reveals microstructural details hitherto unseen.

Hydrogen-bonding A(LS)2-type low-molecular-mass gelator and its thermotropic mesomorphic behavior.

PubMed

Hou, Qiufei; Wang, Shichao; Zang, Libin; Wang, Xiaoliang; Jiang, Shimei

2009-10-15

A unique cholesterol-based A(LS)2-type gelator, which is a hydrogen-bonding complex based on an ALS-type non-gelator molecule 3-cholesteryl 4-(trans-2-(4-pyridinyl)vinyl)phenyl succinate and a counterpart 3-cholesteryloxycarbonylpropanoic acid, shows strong gelation ability in alcohol and aromatic solvents. The formed gel has a high Tg at low gelation concentration, and its xerogel shows fibrillar microstructure revealed by scanning electron microscopy (SEM). FTIR confirms the existence of intermolecular hydrogen bond in the gelator, and X-ray diffraction (XRD) analysis reveals that the gelator possesses a folded conformation in gel and self-assembles into the fibrillar structure mainly by van der Waals interaction between cholesteryl moieties of the gelator. Further more, the thermotropic behavior of the xerogel is studied by differential scanning calorimetry (DSC) and polarized optical microscopy (POM), which shows typical optical textures of liquid crystals.

Hydrophobic Coatings on Cotton Obtained by in Situ Plasma Polymerization of a Fluorinated Monomer in Ethanol Solutions.

PubMed

Molina, Ricardo; Teixidó, Josep Maria; Kan, Chi-Wai; Jovančić, Petar

2017-02-15

Plasma polymerization using hydrophobic monomers in the gas phase is a well-known technology to generate hydrophobic coatings. However, synthesis of functional hydrophobic coatings using plasma technology in liquids has not yet been accomplished. This work is consequently focused on polymerization of a liquid fluorinated monomer on cotton fabric initiated by atmospheric plasma in a dielectric barrier discharge configuration. Functional hydrophobic coatings on cotton were successfully achieved using in situ atmospheric plasma-initiated polymerization of fluorinated monomer dissolved in ethanol. Gravimetric measurements reveal that the amount of polymer deposited on cotton substrates can be modulated with the concentration of monomer in ethanol solution, and cross-linking reactions occur during plasma polymerization of a fluorinated monomer even without the presence of a cross-linking agent. FTIR and XPS analysis were used to study the chemical composition of hydrophobic coatings and to get insights into the physicochemical processes involved in plasma treatment. SEM analysis reveals that at high monomer concentration, coatings possess a three-dimensional pattern with a characteristic interconnected porous network structure. EDX analysis reveals that plasma polymerization of fluorinated monomers takes place preferentially at the surface of cotton fabric and negligible polymerization takes place inside the cotton fabric. Wetting time measurements confirm the hydrophobicity of cotton coatings obtained although equilibrium moisture content was slightly decreased. Additionally, the abrasion behavior and resistance to washing of plasma-coated cotton has been evaluated.

Preparation of a Ytterbium-tagged Gunshot Residue Standard for Quality Control in the Forensic Analysis of GSR.

PubMed

Hearns, Nigel G R; Laflèche, Denis N; Sandercock, Mark L

2015-05-01

Preparation of a ytterbium-tagged gunshot residue (GSR) reference standard for scanning electron microscopy and energy dispersive X-ray spectroscopic (SEM-EDS) microanalysis is reported. Two different chemical markers, ytterbium and neodymium, were evaluated by spiking the primers of 38 Special ammunition cartridges (no propellant, no projectile) and discharging them onto 12.7 mm diameter aluminum SEM pin stubs. Following SEM-EDS microanalysis, the majority of tri-component particles containing lead, barium, and antimony (PbBaSb) were successfully tagged with the chemical marker. Results demonstrate a primer spiked with 0.75% weight percent of ytterbium nitrate affords PbBaSb particles characteristic of GSR with a ytterbium inclusion efficiency of between 77% and 100%. Reproducibility of the method was verified, and durability of the ytterbium-tagged tri-component particles under repeated SEM-EDS analysis was also tested. The ytterbium-tagged PbBaSb particles impart synthetic traceability to a GSR reference standard and are suitable for analysis alongside case work samples, as a positive control for quality assurance purposes. © 2015 American Academy of Forensic Sciences.

Evaluation of protein immobilization capacity on various carbon nanotube embedded hydrogel biomaterials.

PubMed

Derkus, Burak; Emregul, Kaan Cebesoy; Emregul, Emel

2015-11-01

This study investigates effective immobilization of proteins, an important procedure in many fields of bioengineering and medicine, using various biomaterials. Gelatin, alginate and chitosan were chosen as polymeric carriers, and applied in both their composites and nanocomposite forms in combination with carbon nanotubes (CNTs). The prepared nano/composite structures were characterized using scanning electron microscopy (SEM), Fourier-transform infrared spectroscopy (FTIR), thermal gravimetric analysis (TG) and contact angle analysis (CA). Electrochemical impedance spectroscopy analysis revealed gelatin composites in general to exhibit better immobilization performance relative to the native gelatin which can be attributed to enhanced film morphologies of the composite structures. Moreover, superior immobilization efficiencies were obtained with the addition of carbon nanotubes, due to their conducting and surface enhancement features, especially in the gelatin-chitosan structures due to the presence of structural active groups. Copyright © 2015 Elsevier B.V. All rights reserved.

Preparation and characteristics of epoxy/clay/B4C nanocomposite at high concentration of boron carbide for neutron shielding application

NASA Astrophysics Data System (ADS)

Kiani, Mohammad Amin; Ahmadi, Seyed Javad; Outokesh, Mohammad; Adeli, Ruhollah; Mohammadi, Aghil

2017-12-01

In this research, the characteristics of the prepared samples in epoxy matrix by means of X-ray diffraction (XRD), energy dispersive X-ray spectroscopy (EDS), as well as scanning electron microscope (SEM) are evaluated. Meanwhile, the obtained mechanical properties of the specimen are investigated. Thermogravimetric analysis (TGA) is also employed to evaluate the thermal degradation of manufactured nanocomposites. The thermal neutron absorption properties of nanocomposites containing 3 wt% of montmorillonite nanoclay (closite30B) have been studied experimentally, using an Am-Be point source. Mechanical tests reveal that the higher B4C concentrations, the more tensile strengths, but lower Young's modulus in all samples under consideration. TGA analysis also shows that thermal stability of the nanocomposite, increases in presence of B4C. Finally, neutron absorption analysis shows that increasing the B4C concentration leads to a nonlinearly build-up of neutron absorption cross section.

Electrical transport properties of LiNiV O ceramics

NASA Astrophysics Data System (ADS)

Ram, Moti

2009-08-01

The LiNiV O 4 fine powder has been synthesized by chemical "pyrophoric reaction process". The formation of LiNiV O 4 is confirmed by X-ray diffraction analysis. X-ray analysis shows that the compound has cubic crystal structure with lattice constant ( a=8.2243(2) Å). Microstructure of the sintered pellet is identified by taking the field emission scanning electron microscopy (FE-SEM) pictures, which reveals the grain size as ˜0.2-2 μm. Electrical properties are measured using complex impedance spectroscopy technique. Bulk contribution to electrical response is identified by the analysis of complex plane diagrams. The activation energy calculated from σ vs 10 3/T graph is ˜0.06 eV (25-225 ∘C) and ˜0.55 eV (225-375 ∘C). Complex modulus study shows non-Debye type (polydispersive) conductivity relaxation in the compound.

Partially covered self-expandable metal stents versus polyethylene stents for malignant biliary obstruction: A cost-effectiveness analysis

PubMed Central

Barkun, Alan N; Adam, Viviane; Martel, Myriam; AlNaamani, Khalid; Moses, Peter L

2015-01-01

BACKGROUND/OBJECTIVE: Partially covered self-expandable metal stents (SEMS) and polyethylene stents (PES) are both commonly used in the palliation of malignant biliary obstruction. Although SEMS are significantly more expensive, they are more efficacious than PES. Accordingly, a cost-effectiveness analysis was performed. METHODS: A cost-effectiveness analysis compared the approach of initial placement of PES versus SEMS for the study population. Patients with malignant biliary obstruction underwent an endoscopic retrograde cholangiopancreatography to insert the initial stent. If the insertion failed, a percutaneous transhepatic cholangiogram was performed. If stent occlusion occurred, a PES was inserted at repeat endoscopic retrograde cholangiopancreatography, either in an outpatient setting or after admission to hospital if cholangitis was present. A third-party payer perspective was adopted. Effectiveness was expressed as the likelihood of no occlusion over the one-year adopted time horizon. Probabilities were based on a contemporary randomized clinical trial, and costs were issued from national references. Deterministic and probabilistic sensitivity analyses were performed. RESULTS: A PES-first strategy was both more expensive and less efficacious than an SEMS-first approach. The mean per-patient costs were US$6,701 for initial SEMS and US$20,671 for initial PES, which were associated with effectiveness probabilities of 65.6% and 13.9%, respectively. Sensitivity analyses confirmed the robustness of these results. CONCLUSION: At the time of initial endoscopic drainage for patients with malignant biliary obstruction undergoing palliative stenting, an initial SEMS insertion approach was both more effective and less costly than a PES-first strategy. PMID:26125107

Transcriptome analysis of Jatropha curcas L. flower buds responded to the paclobutrazol treatment.

PubMed

Seesangboon, Anupharb; Gruneck, Lucsame; Pokawattana, Tittinat; Eungwanichayapant, Prapassorn Damrongkool; Tovaranonte, Jantrararuk; Popluechai, Siam

2018-06-01

Jatropha seeds can be used to produce high-quality biodiesel due to their high oil content. However, Jatropha produces low numbers of female flowers, which limits seed yield. Paclobutrazol (PCB), a plant growth retardant, can increase number of Jatropha female flowers and seed yield. However, the underlying mechanisms of flower development after PCB treatment are not well understood. To identify the critical genes associated with flower development, the transcriptome of flower buds following PCB treatment was analyzed. Scanning Electron Microscope (SEM) analysis revealed that the flower developmental stage between PCB-treated and control flower buds was similar. Based on the presence of sex organs, flower buds at 0, 4, and 24 h after treatment were chosen for global transcriptome analysis. In total, 100,597 unigenes were obtained, 174 of which were deemed as interesting based on their response to PCB treatment. Our analysis showed that the JcCKX5 and JcTSO1 genes were up-regulated at 4 h, suggesting roles in promoting organogenic capacity and ovule primordia formation in Jatropha. The JcNPGR2, JcMGP2-3, and JcHUA1 genes were down-regulated indicating that they may contribute to increased number of female flowers and amount of seed yield. Expression of cell division and cellulose biosynthesis-related genes, including JcGASA3, JcCycB3;1, JcCycP2;1, JcKNAT7, and JcCSLG3 was decreased, which might have caused the compacted inflorescences. This study represents the first report combining SEM-based morphology, qRT-PCR and transcriptome analysis of PCB-treated Jatropha flower buds at different stages of flower development. Copyright © 2018 Elsevier Masson SAS. All rights reserved.

Outcome and risk factors assessment for adverse events in advanced esophageal cancer patients after self-expanding metal stents placement.

PubMed

Rodrigues-Pinto, E; Pereira, P; Coelho, R; Andrade, P; Ribeiro, A; Lopes, S; Moutinho-Ribeiro, P; Macedo, G

2017-02-01

Self-expanding metal stents (SEMS) are the treatment of choice for advanced esophageal cancers. Literature is scarce on risk factors predictors for adverse events after SEMS placement. Assess risk factors for adverse events after SEMS placement in advanced esophageal cancer and evaluate survival after SEMS placement. Cross-sectional study of patients with advanced esophageal cancer referred for SEMS placement, during a period of 3 years. Ninety-seven patients with advanced esophageal cancer placed SEMS. Adverse events were more common when tumors were located at the level of the distal esophagus/cardia (47% vs 23%, P = 0.011, OR 3.1), with statistical significance being kept in the multivariate analysis (OR 3.1, P = 0.018). Time until adverse events was lower in the tumors located at the level of the distal esophagus/cardia (P = 0.036). Survival was higher in patients who placed SEMS with curative intent (327 days [126-528] vs. 119 days [91-147], P = 0.002) and in patients submitted subsequently to surgery compared with those who did just chemo/radiotherapy or who did not do further treatment (563 days [378-748] vs. 154 days [133-175] vs. 46 days [20-72], P < 0.001). Subsequent treatment kept statistical significance in the multivariate analysis (HR 3.4, P < 0.001). SEMS allow palliation of dysphagia in advanced esophageal cancer and are associated with an increased out-of-hospital survival, as long as there are conditions for further treatments. Tumors located at the level of the distal esophagus/cardia are associated with a greater number of adverse events, which also occur earlier. © 2016 International Society for Diseases of the Esophagus.

Effect of black clay soil moisture on the electrochemical behavior of API X70 pipeline steel

NASA Astrophysics Data System (ADS)

Hendi, R.; Saifi, H.; Belmokre, K.; Ouadah, M.; Smili, B.; Talhi, B.

2018-03-01

The effect of moisture content variation (20–100 wt.%) on the electrochemical behavior of API X70 pipeline steel buried in the soil of Skikda (East of Algeria) was studied using electrochemical techniques, scanning electron microscopy (SEM), X ray diffraction analysis (XRD) and weight loss measurement. The electrochemical measurements showed that the corrosion current Icorr is directly proportional to the moisture content up to 50 wt.%, beyond this content, this value becomes almost constant. The result were confirmed by electrochemical impedance spectroscopy; the capacitance of the double layer formed on the surface is the highest at 50 wt.%. A single time constant was detected by plotting the Bode diagrams. The steel surface degradation has been appreciated using the scanning electron microscopy observations. A few pitting corrosion at 20 wt.% moisture, followed by more degradation at 50 wt.% have been revealed. However, when the moisture amount exceeded 50 wt.%, the surface became entirely covered by a corrosion product. XRD analysis revealed the dominance of FeOOH and Fe3O4 phases on steel surface for a moisture content of 50 wt.%.

Morphology and Molecular Phylogeny of Raillietina spp. (Cestoda: Cyclophyllidea: Davaineidae) from Domestic Chickens in Thailand.

PubMed

Butboonchoo, Preeyaporn; Wongsawad, Chalobol; Rojanapaibul, Amnat; Chai, Jong-Yil

2016-12-01

Raillietina species are prevalent in domestic chickens ( Gallus gallus domesticus ) in Phayao province, northern Thailand. Their infection may cause disease and death, which affects the public health and economic situation in chicken farms. The identification of Raillietina has been based on morphology and molecular analysis. In this study, morphological observations using light (LM) and scanning electron microscopies (SEM) coupled with molecular analysis of the internal transcribed spacer 2 (ITS2) region and the nicotinamide adenine dinucleotide dehydrogenase subunit 1 (ND1) gene were employed for precise identification and phylogenetic relationship studies of Raillietina spp. Four Raillietina species, including R. echinobothrida, R. tetragona, R. cesticillus , and Raillietina sp., were recovered in domestic chickens from 4 districts in Phayao province, Thailand. LM and SEM observations revealed differences in the morphology of the scolex, position of the genital pore, number of eggs per egg capsule, and rostellar opening surface structures in all 4 species. Phylogenetic relationships were found among the phylogenetic trees obtained by the maximum likelihood and distance-based neighbor-joining methods. ITS2 and ND1 sequence data recorded from Raillietina sp. appeared to be monophyletic. The query sequences of R. echinobothrida, R. tetragona, R. cesticillus , and Raillietina sp. were separated according to the different morphological characters. This study confirmed that morphological studies combined with molecular analyses can differentiate related species within the genus Raillietina in Thailand.

Zircon Supported Copper Catalysts for the Steam Reforming of Methanol

NASA Astrophysics Data System (ADS)

Widiastri, M.; Fendy, Marsih, I. N.

2008-03-01

Steam reforming of methanol (SRM) is known as one of the most favorable catalytic processes for producing hydrogen. Current research on zirconia, ZrO2 supported copper catalyst revealed that CuO/ZrO2 as an active catalyst for the SRM. Zircon, ZrSiO4 is available from the by-product of tin mining. In the work presented here, the catalytic properties of CuO/ZrSiO4 with various copper oxide compositions ranging from 2.70% (catalyst I), 4.12% (catalyst II), and 7.12%-mass (catalyst III), synthesized by an incipient wetness impregnation technique, were investigated to methanol conversion, selectivity towards CO formation, and effect of ZnO addition (7.83%CuO/8.01%ZnO/ZrSiO4 = catalyst V). The catalytic activity was obtained using a fixed bed reactor and the zircon supported catalyst activity was compared to those of CuO/ZnO/Al2O3 catalyst (catalyst IV) and commercial Kujang LTSC catalyst. An X-ray powder diffraction (XRD) analysis was done to identify the abundant phases of the catalysts. The catalysts topography and particle diameter were measured with scanning electron microscopy (SEM) and composition of the catalysts was measured by SEM-EDX, scanning electron microscope-energy dispersive using X-ray analysis. The results of this research provide information on the possibility of using zircon (ZrSiO4) as solid support for SRM catalysts.

Identification of a Multicomponent Traditional Herbal Medicine by HPLC-MS and Electron and Light Microscopy.

PubMed

Liu, Ju-Han; Cheng, Yung-Yi; Hsieh, Chen-Hsi; Tsai, Tung-Hu

2017-12-15

Commercial pharmaceutical herbal products have enabled people to take traditional Chinese medicine (TCM) in a convenient and accessible form. However, the quantity and quality should be additionally inspected. To address the issue, a combination of chemical and physical inspection methods were developed to evaluate the amount of an herbal formula, Xiang-Sha-Liu-Jun-Zi-Tang (XSLJZT), in clinical TCM practice. A high-performance liquid chromatography-tandem mass spectrometry (HPLC-MS) method with electrospray ionization was developed to measure the herbal biomarkers of guanosine, atractylenolide III, glycyrrhizic acid, dehydrocostus lactone, hesperidin, and oleanolic acid from XSLJZT. Scanning electron microscopy (SEM) photographs and light microscopy photographs with Congo red and iodine-KI staining were used to identify the cellulose fibers and starch content. Furthermore, solubility analysis, swelling power test, and crude fiber analysis were contributed to measure the starch additive in pharmaceutical products. The results demonstrated large variations in the chemical components of different pharmaceutical brands. The SEM photographs revealed that the starch was oval, smooth, and granular, and that the raw herbal powder appears stripy, stretched, and filiform. The stained light microscopy photographs of all of the pharmaceutical products showed added starch and raw herbal powder as extenders. The developed chemical and physical methods provide a standard operating procedure for the quantity control of the herbal pharmaceutical products of XSLJZT.

Evaluation of cytotoxicity and corrosion resistance of orthodontic mini-implants.

PubMed

Alves, Celha Borges Costa; Segurado, Márcio Nunes; Dorta, Miriam Cristina Leandro; Dias, Fátima Ribeiro; Lenza, Maurício Guilherme; Lenza, Marcos Augusto

2016-01-01

To evaluate and compare in vitro cytotoxicity and corrosion resistance of mini-implants from three different commercial brands used for orthodontic anchorage. Six mini-implants (Conexão(tm), Neodent(tm) and SIN(tm)) were separately immersed in artificial saliva (pH 6.76) for 30 and 60 days. The cytotoxicity of the corrosion extracts was assessed in L929 cell cultures using the violet crystal and MTT assays, as well as cell morphology under light microscopy. Metal surface characteristics before and after immersion in artificial saliva were assessed by means of scanning electron microscopy (SEM). The samples underwent atomic absorption spectrophotometry to determine the concentrations of aluminum and vanadium ions, constituent elements of the alloy that present potential toxicity. For statistical analysis, one-way ANOVA/Bonferroni tests were used for comparisons among groups with p < 0.05 considered significant. Statistical analysis was carried out with Graph Pad PRISM software Version 4.0. No changes in cell viability or morphology were observed. Mini-implants SEM images revealed smooth surfaces with no obvious traces of corrosion. The extracts assessed by means of atomic absorption spectrophotometry presented concentrations of aluminum and vanadium ions below 1.0 µg/mL and 0.5 µg/mL, respectively. Orthodontic mini-implants manufactured by Conexão(tm), Neodent(tm) and SIN(tm) present high corrosion resistance and are not cytotoxic.

Morphology and Molecular Phylogeny of Raillietina spp. (Cestoda: Cyclophyllidea: Davaineidae) from Domestic Chickens in Thailand

PubMed Central

Butboonchoo, Preeyaporn; Wongsawad, Chalobol; Rojanapaibul, Amnat; Chai, Jong-Yil

2016-01-01

Raillietina species are prevalent in domestic chickens (Gallus gallus domesticus) in Phayao province, northern Thailand. Their infection may cause disease and death, which affects the public health and economic situation in chicken farms. The identification of Raillietina has been based on morphology and molecular analysis. In this study, morphological observations using light (LM) and scanning electron microscopies (SEM) coupled with molecular analysis of the internal transcribed spacer 2 (ITS2) region and the nicotinamide adenine dinucleotide dehydrogenase subunit 1 (ND1) gene were employed for precise identification and phylogenetic relationship studies of Raillietina spp. Four Raillietina species, including R. echinobothrida, R. tetragona, R. cesticillus, and Raillietina sp., were recovered in domestic chickens from 4 districts in Phayao province, Thailand. LM and SEM observations revealed differences in the morphology of the scolex, position of the genital pore, number of eggs per egg capsule, and rostellar opening surface structures in all 4 species. Phylogenetic relationships were found among the phylogenetic trees obtained by the maximum likelihood and distance-based neighbor-joining methods. ITS2 and ND1 sequence data recorded from Raillietina sp. appeared to be monophyletic. The query sequences of R. echinobothrida, R. tetragona, R. cesticillus, and Raillietina sp. were separated according to the different morphological characters. This study confirmed that morphological studies combined with molecular analyses can differentiate related species within the genus Raillietina in Thailand. PMID:28095663

Evaluation of cytotoxicity and corrosion resistance of orthodontic mini-implants

PubMed Central

Alves, Celha Borges Costa; Segurado, Márcio Nunes; Dorta, Miriam Cristina Leandro; Dias, Fátima Ribeiro; Lenza, Maurício Guilherme; Lenza, Marcos Augusto

2016-01-01

ABSTRACT Objective: To evaluate and compare in vitro cytotoxicity and corrosion resistance of mini-implants from three different commercial brands used for orthodontic anchorage. Methods: Six mini-implants (Conexão(tm), Neodent(tm) and SIN(tm)) were separately immersed in artificial saliva (pH 6.76) for 30 and 60 days. The cytotoxicity of the corrosion extracts was assessed in L929 cell cultures using the violet crystal and MTT assays, as well as cell morphology under light microscopy. Metal surface characteristics before and after immersion in artificial saliva were assessed by means of scanning electron microscopy (SEM). The samples underwent atomic absorption spectrophotometry to determine the concentrations of aluminum and vanadium ions, constituent elements of the alloy that present potential toxicity. For statistical analysis, one-way ANOVA/Bonferroni tests were used for comparisons among groups with p < 0.05 considered significant. Statistical analysis was carried out with Graph Pad PRISM software Version 4.0. Results: No changes in cell viability or morphology were observed. Mini-implants SEM images revealed smooth surfaces with no obvious traces of corrosion. The extracts assessed by means of atomic absorption spectrophotometry presented concentrations of aluminum and vanadium ions below 1.0 µg/mL and 0.5 µg/mL, respectively. Conclusion: Orthodontic mini-implants manufactured by Conexão(tm), Neodent(tm) and SIN(tm) present high corrosion resistance and are not cytotoxic. PMID:27901227

Effect of Annealing Temperature on Structural and Optical Properties of Sol-Gel-Derived ZnO Thin Films

NASA Astrophysics Data System (ADS)

Arif, Mohd.; Sanger, Amit; Vilarinho, Paula M.; Singh, Arun

2018-04-01

Nanocrystalline ZnO thin films were deposited on glass substrate via sol-gel dip-coating technique then annealed at 300°C, 400°C, and 500°C for 1 h. Their optical, structural, and morphological properties were studied using ultraviolet-visible (UV-Vis) spectrophotometry, x-ray diffraction (XRD) analysis, and scanning electron microscopy (SEM). XRD diffraction revealed that the crystalline nature of the thin films increased with increasing annealing temperature. The c-axis orientation improved, and the grain size increased, as indicated by increased intensity of the (002) plane peak at 2θ = 34.42° corresponding to hexagonal ZnO crystal. The average crystallite size of the thin films ranged from 13 nm to 23 nm. Increasing the annealing temperature resulted in larger crystallite size and higher crystallinity with increased surface roughness. The grain size according to SEM analysis was in good agreement with the x-ray diffraction data. The optical bandgap of the thin films narrowed with increasing annealing temperature, lying in the range of 3.14 eV to 3.02 eV. The transmission of the thin films was as high as 94% within the visible region. The thickness of the thin films was 400 nm, as measured by ellipsometry, after annealing at the different temperatures of 300°C, 400°C, and 500°C.

Scanning electron microscopy fractography analysis of fractured hollow implants.

PubMed

Sbordone, Ludovico; Traini, Tonino; Caputi, Sergio; Scarano, Antonio; Bortolaia, Claudia; Piattelli, Adriano

2010-01-01

Fracture of the implant is one of the possible complications affecting dental implants; it is a rare event but of great clinical relevance. The aim of the present study was to perform a scanning electron microscopy (SEM) fractography evaluation of 7 International Team for oral Implantology (ITI) hollow implants removed because of fracture. The most common clinical risk factors, such as malocclusion, bruxism, and cantilevers on the prosthesis, were absent. Seven fractured ITI hollow implants were retrieved from 5 patients and were analyzed with the use of SEM. SEM analysis showed typical signs of a cleavage-type fracture. Fractures could be due to an association of multiple factors such as fatigue, inner defects, material electrochemical problems, and tensocorrosion.

Geomicrobiology of Fe-rich crusts in Lake Superior sediment

NASA Astrophysics Data System (ADS)

Dittrich, M.; Monreau, L.; Quazi, S.; Raoof, B.; Chesnyuk, A.; Katsev, S.; Fulthorpe, R.

2012-04-01

The limnological puzzles of Lake Superior are increasingly attracting scientists, and very little is known about the sediments and their associated microflora. The sediments are organic poor (less than 5%C) and the lake is deep oligotrophic, with water temperatures at the bottom around 3C. Previous studies reveal Fe-rich layers in the sediments at multiple loccations around the lake. The origin and mechanisms of formation of this layer remain unknown. In this study we investigated geochemical and microbiological processes that may lead to the formation of a two cm thick iron layer about 10 cm below the sediment surface. Sediment cores from two stations (EM, 230m water depth and ED, 310m water depth) in the East Basin were used. We monitored oxygen and pH depth profiles with microsensors, porewater and sediment solid matter were analyzed for nutrient and metal contents. Furthermore, phosphorus and iron sequantial extractions of sediment cores have been perfomed. The total cell count was determined using DAPI epifluoresence microscopy. DNA was extracted from the sediment samples and 16S ribosonal RNA amplicons were analyzed with denaturing gradient gel electrophoresis (DGGE). For a more in depth analysis, DNA samples from 8-10 cm and 10-12 cm were sent to the Research and Testing Lab (Texas) for pyrosequencing of 16S rRNA gene amplicons amplified using barcoded universal primers 27f-519r. The scanning electron microscope (SEM) images from the iron layer 10-12cm show filaments that were encrusted with spheres ca. 20 nm in diameter. SEM observations of thin sections also indicate the presence of very fine particles showing various morphologies. Analyses of the deposit material by SEM and energy dispersive X-ray spectroscopy (EDS) indicate that bacteria cells surfaces served as nucleation surfaces for Fe-oxide formation. EDS line-scans through bacterial cells covered with precipitates reveal phosphorus and carbon peaks at interface between cell surface and Fe-particles. The cluster analysis performed on the DGGE separation of ribosomal RNA gene fragments revealed that the two iron layers were not highly similar to each other. We obtained a total of 26,062 16S rRNA gene sequence reads from the two iron layers and the layers directly above them, which were clustered into operational taxonomic units sharing 80% similarity or more. 64-70% of these clusters could not be classified below the phylum level. While the 8-10 cm sediment layers were dominated (46.5% of reads) by relatives of Paenisporosarcina, the iron layers contained far fewer gram positive organisms, far more proteobacteria, and an a high proportion of Nitrospira species which show relatively high similarity to organisms found in an iron II rich seep.

Labyrinths, columns and cavities: new internal features of pollen grain walls in the Acanthaceae detected by FIB-SEM.

PubMed

House, Alisoun; Balkwill, Kevin

2016-03-01

External pollen grain morphology has been widely used in the taxonomy and systematics of flowering plants, especially the Acanthaceae which are noted for pollen diversity. However internal pollen wall features have received far less attention due to the difficulty of examining the wall structure. Advancing technology in the field of microscopy has made it possible, with the use of a focused ion beam-scanning electron microscope (FIB-SEM), to view the structure of pollen grain walls in far greater detail and in three dimensions. In this study the wall structures of 13 species from the Acanthaceae were investigated for features of potential systematic relevance. FIB-SEM was applied to obtain precise cross sections of pollen grains at selected positions for examining the wall ultrastructure. Exploratory studies of the exine have thus far identified five basic structural types. The investigations also show that similar external pollen wall features may have a distinctly different internal structure. FIB-SEM studies have revealed diverse internal pollen wall features which may now be investigated for their systematic and functional significance.

In situ SEM Study of Lithium Intercalation in individual V 2O 5 Nanowires

DOE PAGES

Strelcov, Evgheni; Cothren, Joshua E.; Leonard, Donovan N.; ...

2015-01-08

Progress in rational engineering of Li-ion batteries requires better understanding of the electrochemical processes and accompanying transformations in the electrode materials on multiple length scales. In spite of recent progress in utilizing transmission electron microscopy (TEM) to analyze these materials, in situ scanning electron microscopy (SEM) was mostly overlooked as a powerful tool that allows probing these phenomena on the nano and mesoscale. In this paper, we report on in situ SEM study of lithiation in a V 2O 5-based single-nanobelt battery with ionic liquid electrolyte. Coupled with cyclic voltammetry measurements, in situ SEM revealed the peculiarities of subsurface intercalation,more » formation of solid-electrolyte interface (SEI) and electromigration of liquid. We observed that single-crystalline vanadia nanobelts do not undergo large-scale amorphization or fracture during electrochemical cycling, but rather transform topochemically with only a slight shape distortion. Lastly, the SEI layer seems to have significant influence on the lithium ion diffusion and overall capacity of the single-nanobelt battery.« less

Iron encrustations on filamentous algae colonized by Gallionella-related bacteria in a metal-polluted freshwater stream

NASA Astrophysics Data System (ADS)

Mori, J. F.; Neu, T. R.; Lu, S.; Händel, M.; Totsche, K. U.; Küsel, K.

2015-09-01

Filamentous macroscopic algae were observed in slightly acidic to circumneutral (pH 5.9-6.5), metal-rich stream water that leaked out from a former uranium mining district (Ronneburg, Germany). These algae differed in color and morphology and were encrusted with Fe-deposits. To elucidate their potential interaction with Fe(II)-oxidizing bacteria (FeOB), we collected algal samples at three time points during summer 2013 and studied the algae-bacteria-mineral compositions via confocal laser scanning microscopy (CLSM), scanning electron microscopy (SEM), Fourier transform infrared (FTIR) spectra, and a 16S and 18S rRNA gene-based bacterial and algae community analysis. Surprisingly, sequencing analysis of 18S rRNA gene regions of green and brown algae revealed high homologies with the freshwater algae Tribonema (99.9-100 %). CLSM imaging indicated a loss of active chloroplasts in the algae cells, which may be responsible for the change in color in

Endoscopic stenting for hilar cholangiocarcinoma: efficacy of unilateral and bilateral placement of plastic and metal stents in a retrospective review of 480 patients

PubMed Central

2012-01-01

Background Endoscopic biliary drainage of hilar cholangiocarcinoma is controversial with respect to the optimal types of stents and the extent of drainage. This study evaluated endoscopic palliation in patients with hilar cholangiocarcinoma using self-expandable metallic stents (SEMS) and plastic stents (PS).We also compared unilateral and bilateral stent placement according to the Bismuth classification. Methods Data on 480 patients receiving endoscopic biliary drainage for hilar cholangiocarcinoma between September 1995 and December 2010 were retrospectively reviewed to evaluate the following outcome parameters: technical success (TS), functional success (FS), early and late complications, stent patency and survival. Patients were followed from stent insertion until death or stent occlusion. Patients were divided into 3 groups according to the Bismuth classification (Group 1, type I; Group 2, type II; Group 3, type > III). Results The initial stent insertion was successful in 450 (93.8%) patients. TS was achieved in 204 (88.3%) patients treated with PS and in 246 (98.8%) patients palliated with SEMS (p < 0.001). In the intention-to-treat (ITT) analysis, the FS in patients treated with SEMS (97.9%) was significantly higher than in patients treated with PS (84.8%) (p < 0.001). Late complications occurred in 115 (56.4%) patients treated with PS and 60 (24.4%) patients treated with SEMS (p < 0.001). The median duration of stent patency in weeks (w) were as follows: 20 w in patients palliated with PS and 27 w in patients treated with SEMS (p < 0.0001). In Group 2, the median duration of PS patency was 17 w and 18 w for unilateral and bilateral placement, respectively (p = 0.0004); the median duration of SEMS patency was 24 w and 29 w for unilateral and bilateral placement, respectively (p < 0.0001). Multivariate analysis using the Poisson regression showed that SEMS placement (B = 0.48; P < 0.01) and bilateral deployment (B = 0.24; P < 0.01) were the only independent prognostic factors associated with stent patency. Conclusions SEMS insertion for the palliation of hilar cholangiocarcinoma offers higher technical and clinical success rates in the ITT analysis as well as lower complication rates and a superior cumulative stent patency when compared with PS placement in all Bismuth classifications. The cumulative patency of bilateral SEMS or PS stents was significantly higher than that of unilateral SEMS or PS stents, with lower occlusion rates in Bismuth II patients. PMID:22873816

High Resolution CryoFESEM of Microbial Surfaces

NASA Astrophysics Data System (ADS)

Erlandsen, Stanley; Lei, Ming; Martin-Lacave, Ines; Dunny, Gary; Wells, Carol

2003-08-01

The outer surfaces of three microorganisms, Giardia lamblia, Enterococcus faecalis, and Proteus mirabilis, were investigated by cryo-immobilization followed by sublimation of extracellular ice and cryocoating with either Pt alone or Pt plus carbon. Cryocoated samples were examined at [minus sign]125°C in either an in-lens field emission SEM or a below-the-lens field emission SEM. Cryocoating with Pt alone was sufficient for low magnification observation, but attempts to do high-resolution imaging resulted in radiolysis and cracking of the specimen surface. Double coating with Pt and carbon, in combination with high resolution backscatter electron detectors, enabled high-resolution imaging of the glycocalyx of bacteria, revealing a sponge-like network over the surface. High resolution examination of bacterial flagella also revealed a periodic substructure. Common artifacts included radiolysis leading to “cracking” of the surface, and insufficient deposition of Pt resulting in the absence of detectable surface topography.

Improved cell viability and hydroxyapatite growth on nitrogen ion-implanted surfaces

NASA Astrophysics Data System (ADS)

Shafique, Muhammad Ahsan; Murtaza, G.; Saadat, Shahzad; Uddin, Muhammad K. H.; Ahmad, Riaz

2017-08-01

Stainless steel 306 is implanted with various doses of nitrogen ions using a 2 MV pelletron accelerator for the improvement of its surface biomedical properties. Raman spectroscopy reveals incubation of hydroxyapatite (HA) on all the samples and it is found that the growth of incubated HA is greater in higher ion dose samples. SEM profiles depict uniform growth and greater spread of HA with higher ion implantation. Human oral fibroblast response is also found consistent with Raman spectroscopy and SEM results; the cell viability is found maximum in samples treated with the highest (more than 300%) dose. XRD profiles signified greater peak intensity of HA with ion implantation; a contact angle study revealed hydrophilic behavior of all the samples but the treated samples were found to be lesser hydrophilic compared to the control samples. Nitrogen implantation yields greater bioactivity, improved surface affinity for HA incubation and improved hardness of the surface.

Three-dimensional textures and defects of soft material layering revealed by thermal sublimation.

PubMed

Yoon, Dong Ki; Kim, Yun Ho; Kim, Dae Seok; Oh, Seong Dae; Smalyukh, Ivan I; Clark, Noel A; Jung, Hee-Tae

2013-11-26

Layering is found and exploited in a variety of soft material systems, ranging from complex macromolecular self-assemblies to block copolymer and small-molecule liquid crystals. Because the control of layer structure is required for applications and characterization, and because defects reveal key features of the symmetries of layered phases, a variety of techniques have been developed for the study of soft-layer structure and defects, including X-ray diffraction and visualization using optical transmission and fluorescence confocal polarizing microscopy, atomic force microscopy, and SEM and transmission electron microscopy, including freeze-fracture transmission electron microscopy. Here, it is shown that thermal sublimation can be usefully combined with such techniques to enable visualization of the 3D structure of soft materials. Sequential sublimation removes material in a stepwise fashion, leaving a remnant layer structure largely unchanged and viewable using SEM, as demonstrated here using a lamellar smectic liquid crystal.

Third order nonlinear optical properties of Mn doped CeO2 nanostructures

NASA Astrophysics Data System (ADS)

Mani Rahulan, K.; Angeline Little Flower, N.; Annie Sujatha, R.; Mohana Priya, P.; Gopalakrishnan, C.

2018-05-01

Mn doped CeO2 nanoparticles with different ratios of Mn were synthesized by hydrothermal method and their structural properties were characterized using X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR) and Scanning electron microscopy (SEM). XRD patterns revealed that the peaks are highly crystalline structure with no segregation of Mn. The surface morphology from SEM reveals that particle size decreases with increase in Mn concentration. Nonlinear optical studies of the samples were measured by single-beam open aperture Z-scan technique using 5 ns laser pulses at 532 nm. The measured optical nonlinearity of all the samples exhibit typical third order nonlinear optical behavior including two-photon absorption (2 PA) and reverse saturable absorption (RSA). The experimental results show that the presence of RSA in these nanoparticles makes them a promising material for the fabrication of optical limiting devices. .

Analyzing indirect secondary electron contrast of unstained bacteriophage T4 based on SEM images and Monte Carlo simulations

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

Ogura, Toshihiko, E-mail: t-ogura@aist.go.jp

2009-03-06

The indirect secondary electron contrast (ISEC) condition of the scanning electron microscopy (SEM) produces high contrast detection with minimal damage of unstained biological samples mounted under a thin carbon film. The high contrast image is created by a secondary electron signal produced under the carbon film by a low acceleration voltage. Here, we show that ISEC condition is clearly able to detect unstained bacteriophage T4 under a thin carbon film (10-15 nm) by using high-resolution field emission (FE) SEM. The results show that FE-SEM provides higher resolution than thermionic emission SEM. Furthermore, we investigated the scattered electron area within themore » carbon film under ISEC conditions using Monte Carlo simulation. The simulations indicated that the image resolution difference is related to the scattering width in the carbon film and the electron beam spot size. Using ISEC conditions on unstained virus samples would produce low electronic damage, because the electron beam does not directly irradiate the sample. In addition to the routine analysis, this method can be utilized for structural analysis of various biological samples like viruses, bacteria, and protein complexes.« less

Effect of rotary cutting instruments on the resin-tooth interfacial ultra structure: An in vivo study.

PubMed

Sherawat, Sudhir; Tewari, Sanjay; Duhan, Jigyasa; Gupta, Alpa; Singla, Rakesh

2014-12-01

To evaluate the effect of cutting teeth with different types of burs at various speeds on surface topography of tooth surface and interfacial gap formation at resin-tooth interface. The human molars were divided into seven groups: Diamond bur in airrotor (DA) & micromotor (DM), crosscut carbide bur in airrotor (CCA) & micromotor (CCM), plain carbide bur in airrotor (CA) & micromotor (CM) and #600-grit silicon carbide paper (SiC). In five samples from each group Class II box-only cavities were restored. The occlusal surface of four teeth per group was flattened. Two out of four teeth were acid etched. Teeth were subjected for scanning electron microscopy (SEM). Interfacial gap was observed in all groups with no significant difference. SEM observations revealed CA, CCA & DA were coarser than CM, CCM, DM and SiC. SEM of etched tooth surfaces revealed complete removal of amorphous smear layer in CA & CM, partial removal in CCA, CCM, DA & DM and no removal in SiC. Selecting an appropriate bur and its speed may not play an important role in bonding in terms of interfacial gap formation. Variable changes were observed in surface topography with different burs before and after acid etching. Key words:Surface topography, resin-tooth interface, interfacial gap, bonding.

Effect of rotary cutting instruments on the resin-tooth interfacial ultra structure: An in vivo study

PubMed Central

Sherawat, Sudhir; Tewari, Sanjay; Duhan, Jigyasa; Singla, Rakesh

2014-01-01

Objectives: To evaluate the effect of cutting teeth with different types of burs at various speeds on surface topography of tooth surface and interfacial gap formation at resin-tooth interface. Material and Methods: The human molars were divided into seven groups: Diamond bur in airrotor (DA) & micromotor (DM), crosscut carbide bur in airrotor (CCA) & micromotor (CCM), plain carbide bur in airrotor (CA) & micromotor (CM) and #600-grit silicon carbide paper (SiC). In five samples from each group Class II box-only cavities were restored. The occlusal surface of four teeth per group was flattened. Two out of four teeth were acid etched. Teeth were subjected for scanning electron microscopy (SEM). Results: Interfacial gap was observed in all groups with no significant difference. SEM observations revealed CA, CCA & DA were coarser than CM, CCM, DM and SiC. SEM of etched tooth surfaces revealed complete removal of amorphous smear layer in CA & CM, partial removal in CCA, CCM, DA & DM and no removal in SiC. Conclusions: Selecting an appropriate bur and its speed may not play an important role in bonding in terms of interfacial gap formation. Variable changes were observed in surface topography with different burs before and after acid etching. Key words:Surface topography, resin-tooth interface, interfacial gap, bonding. PMID:25674310

In-plane and through-plane non-uniform carbon corrosion of polymer electrolyte fuel cell cathode catalyst layer during extended potential cycles

NASA Astrophysics Data System (ADS)

Ghosh, Sourov; Ohashi, Hidenori; Tabata, Hiroshi; Hashimasa, Yoshiyuki; Yamaguchi, Takeo

2017-09-01

The impact of electrochemical carbon corrosion via potential cycling durability tests mimicking start-stop operation events on the microstructure of the cathode catalyst layer in polymer electrolyte fuel cells (PEFCs) is investigated using focused ion beam (FIB) fabrication without/with the pore-filling technique and subsequent scanning electron microscope (SEM) observations. FIB/SEM investigations without pore-filling reveals that the durability test induces non-uniform cathode shrinking across the in-plane direction; the thickness of the catalyst layer decreases more under the gas flow channel compared to the area under the rim of the flow field. Furthermore, FIB/SEM investigations with the pore-filling technique reveal that the durability test also induces non-uniform cathode shrinking in the through-plane direction; the pores in the area close to the membrane are more shrunken compared with those close to the microporous layer. In particular, a thin area (1-1.5 μm) close to the membrane is found to be severely damaged; it includes closed pores that hinder mass transport through the catalyst layer. It is suggested that uneven carbon corrosion and catalyst layer compaction are responsible for the performance loss during potential cycling operation of PEFCs.

Sarcoptic mange in free-ranging raccoon dogs (Nyctereutes procyonoides) in Japan.

PubMed

Ninomiya, Hiroyoshi; Ogata, Munetsugu

2005-06-01

Sarcoptes scabiei infestation was diagnosed in three freshly dead free-ranging raccoon dogs (Nyctereutes procyonoides) in Kanagawa Prefecture, Japan. The dogs presented with an alopecic pruritic skin disease, with signs of alopecia on the ears, muzzle, around the eyes, elbow, thigh and the neck, and hyperpigmented and crusted skin lesions, which had a severe malodour. Skin scrapings revealed the presence of the mite Sarcoptes scabiei. Histopathology of lesions demonstrated marked acanthosis, hyperkeratosis, parakeratosis and fungal elements, which were subsequently identified as Acremonium sp., Alternaria sp. and an unknown fungus. Mite segments were located mainly in the stratum corneum and also in the stratum granulosum. Tunnels could be observed in the hyperkeratotic stratum corneum. Scanning electron microscopy (SEM) revealed the tortoise-like Sarcoptes scabiei with four long bristles, suckers and blade-like claws on legs 1 and 2, cuticular spines, prominent body striations and a terminal anus. SEM also revealed an adult female mite digging a tunnel with the head wedged into the very end of the closed burrow. Tunnels filled with eggshells, corneocyte debris and faecal pellets were also observed.

Reintervention for stent occlusion after bilateral self-expandable metallic stent placement for malignant hilar biliary obstruction.

PubMed

Inoue, Tadahisa; Naitoh, Itaru; Okumura, Fumihiro; Ozeki, Takanori; Anbe, Kaiki; Iwasaki, Hiroyasu; Nishie, Hirotada; Mizushima, Takashi; Sano, Hitoshi; Nakazawa, Takahiro; Yoneda, Masashi; Joh, Takashi

2016-11-01

Endoscopic reintervention for stent occlusions following bilateral self-expandable metallic stent (SEMS) placement for malignant hilar biliary obstruction (MHBO) is challenging, and time to recurrent biliary obstruction (RBO) of the revisionary stent remains unclear. We aimed to clarify a suitable reintervention method for stent occlusions following bilateral SEMS placement for MHBO. Between 2002 and 2014, 52 consecutive patients with MHBO who underwent endoscopic reintervention for stent occlusion after bilateral SEMS placement were enrolled at two university hospitals and one tertiary care referral center. We retrospectively evaluated the technical and functional success rates of the reinterventions, and the time to RBO of the revisionary stents. Technical and functional success rates of the reinterventions were 92% (48/52) and 90% (43/48), respectively. Univariate analysis did not determine any significant predictive factors for technical and functional failures. Median time to RBO of the revisionary stents was 68 days. Median time to RBO was significantly longer for revisionary SEMS placement than for plastic stent placement (131 days vs 47 days, respectively; log-rank test, P = 0.005). Revisionary SEMS placement was the only independent factor that was significantly associated with a longer time to RBO of the revisionary stent in the multivariate Cox proportional hazards analysis (hazard ratio 0.37; 95% confidence interval 0.14-0.95; P = 0.039). Revisionary SEMS placement is a suitable endoscopic reintervention method for stent occlusion following bilateral SEMS placement from the perspective of time to RBO of the revisionary stent. © 2016 Japan Gastroenterological Endoscopy Society.

Investigation of MeV-Cu implantation and channeling effects into porous silicon formation

NASA Astrophysics Data System (ADS)

Ahmad, M.; Naddaf, M.

2011-11-01

P-type (1 1 1) silicon wafers were implanted by copper ions (2.5 MeV) in channeling and random directions using ion beam accelerator of the Atomic Energy Commission of Syria (AECS). The effect of implantation direction on formation process of porous silicon (PS) using electrochemical etching method has been investigated using scanning electron microscope (SEM) and photoluminescence (PL) techniques. SEM observations revealed that the size, shape and density of the formed pores are highly affected by the direction of beam implantation. This in turn is seen to influence the PL behavior of the PS.

Fully vs. partially covered selfexpandable metal stent for palliation of malignant esophageal strictures: a randomized trial (the COPAC study).

PubMed

Didden, Paul; Reijm, Agnes N; Erler, Nicole S; Wolters, Leonieke M M; Tang, Thjon J; Ter Borg, Pieter C J; Leeuwenburgh, Ivonne; Bruno, Marco J; Spaander, Manon C W

2018-06-12

 Covered esophageal self-expandable metal stents (SEMSs) are currently used for palliation of malignant dysphagia. The optimal extent of the covering to prevent recurrent obstruction is unknown. Therefore, we aimed to compare fully covered (FC) versus partially covered (PC) SEMSs in patients with incurable malignant esophageal stenosis.  In this multicenter randomized controlled trial, 98 incurable patients with dysphagia caused by a malignant stricture of the esophagus or cardia were randomized 1:1 to an FC-SEMS or PC-SEMS. The primary outcome was recurrent obstruction after endoscopic SEMS placement. Secondary outcomes were technical and clinical success, adverse events, and health-related quality of life (HRQoL). Patients were followed until 6 months after SEMS placement or to SEMS removal, second SEMS insertion, or death, whichever came first.  Recurrent obstruction after SEMS placement was similar for both types of stents: 19 % for FC-SEMSs and 22 % for PC-SEMSs ( P  = 0.65). The times to recurrent obstruction did not differ. The frequency of adverse events was similar between the two groups, with major adverse events occurring in 38 % and 47 % of patients for FC-SEMSs and PC-SEMSs, respectively ( P  = 0.34). No significant differences were seen in technical success, improvement of dysphagia, and HRQoL. Proximal esophageal stenosis and female sex were independently associated with recurrent obstruction and/or major adverse events.  Esophageal FC-SEMSs did not reveal a lower recurrent obstruction rate compared with PC-SEMSs in the palliative management of malignant dysphagia. © Georg Thieme Verlag KG Stuttgart · New York.

Crystalline TiO 2 grafted with poly(2-methacryloyloxyethyl phosphorylcholine) via surface-initiated atom-transfer radical polymerization

NASA Astrophysics Data System (ADS)

Zhao, Yuancong; Tu, Qiufen; Wang, Jin; Huang, Qiongjian; Huang, Nan

2010-12-01

Crystalline TiO 2 films were prepared by unbalanced magnetron sputtering and the structure was confirmed by XRD. An organic layer of 11-hydroxyundecylphosphonic acid (HUPA) was prepared on the TiO 2 films by self-assembling, and the HUPA on TiO 2 films was confirmed by FTIR analysis. Simultaneously, hydroxyl groups were introduced in the phosphonic acid molecules to provide a functionality for further chemical modification. 2-Methacryloyloxyethyl phosphorylcholine (MPC), a biomimetic monomer, was chemically grafted on the HUPA surfaces at room temperature by surface-initiated atom-transfer radical polymerization. The surface characters of TiO 2 films modified by poly-MPC were confirmed by FTIR, XPS and SEM analysis. Platelet adhesion experiment revealed that poly-MPC modified surface was effective to inhibit platelet adhesion in vitro.

Physicochemical properties, in-vitro digestibility and structural elucidation of RS4 from rice starch.

PubMed

Ashwar, Bilal Ahmad; Gani, Adil; Shah, Asima; Masoodi, Farooq Ahmad

2017-12-01

Starches extracted from four different rice cultivars were phosphorylated by using STMP/STPP to make modified food starches with high contents of type 4 resistant starch (RS4). The results revealed 10- fold improvement in RS4 content by the phosphorylation of starch. The phosphorus % and DS values of rice starches ranged from 0.33 to 0.35, and 0.016 to 0.018, respectively. FT-IR spectroscopy showed reduction of OH stretching band at 3290cm-1 and the appearance of PO at 1244-1266cm-1 which confirms crosslinking of starch with STMP/STPP. Phosphorylation was found to increase water absorption capacity, oil absorption capacity, bile-acid binding and lightness, whereas amylose content, swelling power, solubility index and light transmittance were decreased with phosphorylation. DSC analyses revealed increase in thermal transition temperatures of the crosslinked starches which suggests that the application of STMP/STPP as a crosslinker can improve the integrality and stability of starch. SEM micro-graphs revealed that phosphorylated rice starch granules retained their integrity, while some fissures appeared on the surface of some granules. XRD analysis revealed decreased crystallinity of RS4 rice starches. Copyright © 2017 Elsevier B.V. All rights reserved.

Silk fibroin/gold nanocrystals: a new example of biopolymer-based nanocomposites

NASA Astrophysics Data System (ADS)

Noinville, S.; Garnier, A.; Courty, A.

2017-05-01

The dispersion of nanoparticles in ordered polymer nanostructures can provide control over particle location and orientation, and pave the way for tailored nanomaterials that have enhanced mechanical, electrical, or optical properties. Here we used silk fibroin, a natural biopolymer, to embed gold nanocrystals (NCs), so as to obtain well-ordered structures such as nanowires and self-assembled triangular nanocomposites. Monodisperse gold NCs synthesized in organic media are mixed to silk fibroin and the obtained nanocomposites are characterized by UV-visible spectroscopy, transmission electron microscopy (TEM), scanning electron microscopy (FE-SEM), atomic force microscopy (AFM) and Infrared spectroscopy. The optical properties study of gold NCs and silk-gold nanocomposites shows that the Surface Plasmon band is blue shifted compared to gold NCs. The size and shape of NCs gold superlattices can be well controlled by the presence of silk fibroin giving nanowires and also self-assembled triangular nanocomposites as characterized by TEM, FE-SEM and AFM. The strong interaction between gold NCs and silk fibroin is also revealed by the conformation change of silk protein in presence of gold NCs, as shown by FTIR analysis. The formation of such ordered nanocomposites (gold NCs/silk fibroin) will provide new nanoplasmonic devices.

O electrolyte for bio-application

NASA Astrophysics Data System (ADS)

Naddaf, M.; Almariri, A.

2014-09-01

Porous silicon (PS) has been prepared in the dark by anodic etching of n+-type (111) silicon substrate in a HF:HCl:C2H5OH:H2O2:H2O electrolyte. The processed PS layer is characterized by means of photoluminescence (PL) spectroscopy, scanning electron microscope (SEM), water contact angle (CA) measurements, Fourier transform infrared (FTIR) spectroscopy, X-ray photoelectron spectroscopy (XPS) and micro-Raman scattering. The CA of fresh PS layer is found to be ~142°. On aging at ambient conditions, the CA decreases gently to reach ~133° after 3 month, and then it is stabilized for a prolonged time of aging. The visible PL emission from the PS layer also exhibits a good stability against aging time. The FTIR and XPS measurements and analysis show that the stable aged PS layer has rather SiO2-rich surface. The micro/nanostructure nature of the PS layer is revealed from SEM and micro-Raman results and correlated to CA results. Stable hydrophobic surface of oxidized PS layer is attractive for bio-applications. The efficiency of the produced PS layers as an entrapping template for specific immobilization of IgG2a antibody via physical absorption process is demonstrated.

Investigation on the storage of benzotriazole corrosion inhibitor in TiO2 nanotube

NASA Astrophysics Data System (ADS)

Nguyen, Thi Dieu Hang; Tiep Nong, Thanh; Quang Nguyen, Van; Quyen Nguyen, The; Le, Quang Trung

2018-06-01

The present paper describes different methods for storing the benzotriazole (BTA) corrosion inhibitor in the titanium dioxide nanotubes (TNT) as nanocontainers. Three methods were used, including the vacuum impregnation at ambient temperature, the vacuum impregnation at cooling temperature () and the rotary vacuum evaporation. TNT, BTA and BTA/TNT products were characterized using scanning electron microscopy (SEM), transmission electron microscopy (TEM), Brunauer-Emmett-Teller (BET) surface area, differential scanning calorimetry (DSC), thermogravimetric analysis (TGA) and Fourier transform infrared (FT-IR) spectroscopy. nanotube powder was synthesized by hydrothermal treatment from the inexpensive spherical commercial precursor. The results obtained from SEM, TEM images and BET values showed the successful synthesis of TNT with a homogeneous morphology of nano size tubes and a large specific surface . The existence of BTA in TNT was demonstrated. The BTA/TNT obtained via the rotary vacuum evaporation contained a very significant amount of BTA (66.6 weight %) but BTA existed mostly outside the nanotubes. Two processes of vacuum impregnation at ambient temperature and vacuum impregnation at cooling temperature revealed that there was about 8 weight % BTA stored in BTA/TNT product and BTA was present mostly inside the nanotubes.

Comparing the Effectiveness of Polymer Debriding Devices Using a Porcine Wound Biofilm Model.

PubMed

Wilkinson, Holly N; McBain, Andrew J; Stephenson, Christian; Hardman, Matthew J

2016-11-01

Objective: Debridement to remove necrotic and/or infected tissue and promote active healing remains a cornerstone of contemporary chronic wound management. While there has been a recent shift toward less invasive polymer-based debriding devices, their efficacy requires rigorous evaluation. Approach: This study was designed to directly compare monofilament debriding devices to traditional gauze using a wounded porcine skin biofilm model with standardized application parameters. Biofilm removal was determined using a surface viability assay, bacterial counts, histological assessment, and scanning electron microscopy (SEM). Results: Quantitative analysis revealed that monofilament debriding devices outperformed the standard gauze, resulting in up to 100-fold greater reduction in bacterial counts. Interestingly, histological and morphological analyses suggested that debridement not only removed bacteria, but also differentially disrupted the bacterially-derived extracellular polymeric substance. Finally, SEM of post-debridement monofilaments showed structural changes in attached bacteria, implying a negative impact on viability. Innovation: This is the first study to combine controlled and defined debridement application with a biologically relevant ex vivo biofilm model to directly compare monofilament debriding devices. Conclusion: These data support the use of monofilament debriding devices for the removal of established wound biofilms and suggest variable efficacy towards biofilms composed of different species of bacteria.

Cyclic fatigue resistance of ProTaper Universal instruments when subjected to static and dynamic tests.

PubMed

Lopes, Hélio P; Britto, Izabelle M O; Elias, Carlos N; Machado de Oliveira, Julio C; Neves, Mônica A S; Moreira, Edson J L; Siqueira, José F

2010-09-01

This study evaluated the number of cycles to fracture of ProTaper Universal S2 instruments when subjected to static and dynamic cyclic fatigue tests. ProTaper Universal S2 instruments were used until fracture in an artificial curved canal under rotational speed of 300 rpm in either a static or a dynamic test model. Afterward, the length of the fractured segments was measured and fractured surfaces and helical shafts analyzed by scanning electron microscopy (SEM). The number of cycles to fracture was significantly increased when instruments were tested in the dynamic model (P<.001). Instrument separation occurred at the point of maximum flexure within the artificial canals, i.e., the midpoint of the curved canal segment. SEM analysis revealed that fractured surfaces exhibited characteristics of the ductile mode. Plastic deformation was not observed in the helical shaft of fractured instruments. The number of cycles to fracture ProTaper Universal S2 instruments significantly increased with the use of instruments in a dynamic cyclic fatigue test compared with a static model. These findings reinforce the need for performing continuous pecking motions during rotary instrumentation of curved root canals. Copyright (c) 2010 Mosby, Inc. All rights reserved.

Efficacy of atmospheric pressure dielectric barrier discharge for inactivating airborne pathogens

DOE PAGES

Romero-Mangado, Jaione; Dey, Avishek; Diaz-Cartagena, Diana C.; ...

2017-07-05

Atmospheric pressure plasmas have gained attention in recent years for several environmental applications. This technology could potentially be used to deactivate airborne microorganisms, surface-bound microorganisms, and biofilms. Here, the authors explore the efficacy of the atmospheric pressure dielectric barrier discharge (DBD) to inactivate airborne Staphylococcus epidermidis and Aspergillus niger that are opportunistic pathogens associated with nosocomial infections. This technology uses air as the source of gas and does not require any process gas such as helium, argon, nitrogen, or hydrogen. Moreover, the effect of DBD was studied on aerosolized S. epidermidis and aerosolized A. niger spores via scanning electron microscopymore » (SEM). The morphology observed on the SEM micrographs showed deformations in the cellular structure of both microorganisms. Cell structure damage upon interaction with the DBD suggests leakage of vital cellular materials, which is a key mechanism for microbial inactivation. The chemical structure of the cell surface of S. epidermidis was also analyzed by near edge x-ray absorption fine structure spectroscopy before and after DBD exposure. Our results from surface analysis revealed that reactive oxygen species from the DBD discharge contributed to alterations on the chemistry of the cell membrane/cell wall of S. epidermidis.« less

Perievent panic attack and depression after the World Trade Center disaster: a structural equation model analysis.

PubMed

Adams, Richard E; Boscarino, Joseph A

2011-01-01

Research suggests that perievent panic attacks--panic attacks in temporal proximity to traumatic events--are predictive of later mental health status, including the onset of depression. Using a community sample of New York City residents interviewed 1 year and 2 years after the World Trade Center Disaster, we estimated a structural equation model (SEM) using pre-disaster psychological status and post-disaster life events, together with psychosocial resources, to assess the relationship between perievent panic and later onset depression. Bivariate results revealed a significant association between perievent panic and both year-1 and year-2 depression. Results for the SEM, however showed that perievent panic was predictive of year-1 depression, but not year-2 depression, once potential confounders were controlled Year-2 stressors and year-2 psychosocial resources were the best predictors of year-2 depression onset. Pre-disaster psychological problems were directly implicated in year-1 depression, but not year-2 depression. We conclude that a conceptual model that includes pre- and post-disaster variables best explains the complex causal pathways between psychological status, stressor exposure, perievent panic attacks, and depression onset two years after the World Trade Center attacks.

Microwave synthesis and electrochemical characterization of Mn/Ni mixed oxide for supercapacitor application

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

Prasankumar, T.; Jose, Sujin P., E-mail: sujamystica@yahoo.com; Ilangovan, R.

Nanostructured Mn/Ni mixed metal oxide was synthesized at ambient temperature by facile microwave irradiation technique. The crystal structure and surface morphology were characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM), respectively. X-ray diffraction analysis confirmed the formation of Mn/Ni mixed oxide in rhombohedral phase and the grain size calculated was found to be 87 nm. The irregular spherical morphology of the prepared sample was exhibited by the SEM images. The characteristic peaks of FTIR at about 630 cm{sup −1} and 749 cm{sup −1} were attributed to the Mn-O and Ni-O stretching vibrations respectively. The presence of both Mn and Ni inmore » the prepared sample was validated by the EDS spectra which in turn confirmed the formation of mixed oxide. Cyclic voltammetry and galvanostatic chargedischarge measurements were employed to investigate the electrochemical performance of the mixed oxide. The cyclic voltammetry curves demonstrated good capacitive performance of the sample in the potential window −0.2V to 0.9V. The charge discharge study revealed the suitability of the prepared mixed oxide for the fabrication of supercapacitor electrode.« less

Composite electrodes of activated carbon derived from cassava peel and carbon nanotubes for supercapacitor applications

NASA Astrophysics Data System (ADS)

Taer, E.; Iwantono, Yulita, M.; Taslim, R.; Subagio, A.; Salomo, Deraman, M.

2013-09-01

In this paper, a composite electrode was prepared from a mixture of activated carbon derived from precarbonization of cassava peel (CP) and carbon nanotubes (CNTs). The activated carbon was produced by pyrolysis process using ZnCl2 as an activation agent. A N2 adsorption-desorption analysis for the sample indicated that the BET surface area of the activated carbon was 1336 m2 g-1. Difference percentage of CNTs of 0, 5, 10, 15 and 20% with 5% of PVDF binder were added into CP based activated carbon in order to fabricate the composite electrodes. The morphology and structure of the composite electrodes were investigated by scanning electron microscopy (SEM) and X-ray diffraction (XRD) techniques. The SEM image observed that the distribution of CNTs was homogeneous between carbon particles and the XRD pattern shown the amorphous structure of the sample. The electrodes were fabricated for supercapacitor cells with 316L stainless steel as current collector and 1 M sulfuric acid as electrolyte. An electrochemical characterization was performed by using an electrochemical impedance spectroscopy (EIS) method using a Solatron 1286 instrument and the addition of CNTs revealed to improve the resistant and capacitive properties of supercapacitor cell.

Direct and indirect effects of sociocultural influences on disordered eating among Malaysian male and female university students. A mediation analysis of psychological distress.

PubMed

Gan, Wan Ying; Mohd Nasir, Mohd Taib; Zalilah, Mohd Shariff; Hazizi, Abu Saad

2011-06-01

This study aimed to examine the role of psychological distress in the relationships between sociocultural influences (social pressure to be thin and weight teasing) and disordered eating. Data were collected from 584 university students (59.4% females and 40.6% males), aged 18-24 years old (M=20.6, SD=1.4), selected from four universities in the Klang Valley, Malaysia. Participants completed four standardized questionnaires which measured social pressure to be thin, weight-related teasing, psychological distress and disordered eating. A good fit structural equation modeling (SEM) model was developed for both sexes. For males, the SEM model revealed that sociocultural influences showed an indirect effect on disordered eating through psychological distress. For females, the model showed an indirect effect of sociocultural influences on disordered eating through psychological distress, as well as a direct effect of sociocultural influences on disordered eating. In conclusion, psychological distress mediated the relationships between sociocultural influences and disordered eating in both males and females. Our results suggest that disordered eating intervention programs on reducing psychological distress in university students may be beneficial. Copyright © 2011 Elsevier Ltd. All rights reserved.

Upconversion luminescence of Er3+/Yb3+ doped Sr5(PO4)3OH phosphor powders

NASA Astrophysics Data System (ADS)

Mokoena, P. P.; Swart, H. C.; Ntwaeaborwa, O. M.

2018-04-01

Sr5(PO4)3OH co-doped with Er3+and Yb3+ powder phosphors were synthesized by urea combustion method. The crystal structure was analyzed using X-ray diffraction (XRD). Particle morphology was analyzed using a Jeol JSM 7800F thermal field emission scanning electron microscope (FE-SEM) and the chemical composition analysis was carried out using an Oxford Instruments AzTEC energy dispersive spectrometer (EDS) attached to the FE-SEM. Upconversion emission was measured by using a FLS980 Spectrometer equipped with a 980 nm NIR laser as the excitation source, and a photomultiplier (PMT) detector. The XRD data of the Sr5(PO4)3OH powder exhibited characteristic diffraction patterns of the hexagonal structure referenced in the standard JCPDS card number 00-033-1348. The sharp peaks revealed the formation of crystalline Sr5(PO4)3OH. The powders were made up of hexagonal nanospheres. The enhanced red emission due to the 4F9/2 → 4I15/2 transitions of Er3+ was observed and was attributed to up conversion (UC) energy transfer from Yb3+. The upconversion energy transfer mechanism from Yb3+ to Er3+ is discussed.

Microstructures and Hardness of the High Chromium Oxide Dispersion Strengthened Alloy Fe-25Cr-Y2O3Sintered by the Arc Plasma Sintering (APS)

NASA Astrophysics Data System (ADS)

Bandriyana; Dimyati, Arbi; Sujatno, Agus; Salam, Rohmad; Sumaryo; Untoro, Pudji; Suharno, Bambang

2018-03-01

High chromium ODS alloy has been developed for application as structural material in high temperature nuclear reactor. In the present study, Fe-25Cr-Y2O3 with dispersed 0.5 wt.% Ytria (Y2O3) were synthesized and characterized by means of various techniques as a function of milling time 1, 2 and 3 hours. The alloy synthesis was carried out by the Mechanical Alloying (MA) process and subsequent sintering by means the new plasma technique using the APS apparatus. Scaning Electron Microscopy (SEM) and X-ray diffraction (XRD) were conducted for morphology and phase analysis. Evaluation of the mechanical properties was studied based on the Vickers hardness measurement. SEM examination revealed that the sample after sintering by APS method at different milling duration exhibited some particle aglomeration and homogenized oxide dispersion that obviously strengthened the alloy. The XRD test, however, proved the formation of the main phase Fe-Cr. The alloy showed exceptionally high hardness of 193 VHR which is mainly due to the grain refining that increase by the increasing of the milling time.

Wear Properties of ECAP-Processed AM80 Magnesium Alloy

NASA Astrophysics Data System (ADS)

Gopi, K. R.; Shivananda Nayaka, H.; Sahu, Sandeep

2017-07-01

AM80 magnesium alloy was subjected to equal-channel angular pressing (ECAP), and microstructural evolution was studied using scanning electron microscope (SEM). Grain size was found to decrease up to 3 µm after four passes. An increase in number of ECAP passes led to a corresponding increase in hardness of the processed samples. Unprocessed and ECAP-processed samples were subjected to wear test using pin-on-disk wear test machine to study the wear behavior. Effects of varying loads (30 and 40 N) with sliding distances (2500 and 5000 m) were studied. The results showed reduction in wear mass loss for the ECAP-processed samples in comparison with unprocessed condition. Coefficient of friction (COF) was studied for different loads, and improvement in COF values was observed for ECAP-processed samples compared to unprocessed condition. Worn surfaces were studied using SEM and energy-dispersive x-ray spectrometer, and they exhibited plastic deformation, delamination, plowing, wear debris and oxidation in the sliding direction. X-ray diffraction analysis was conducted on the worn surfaces to identify the phases. It revealed the presence of magnesium oxide and magnesium aluminum oxide which led to oxidation wear in the sliding direction. Wear mechanism was found to be abrasive and oxidation wear.

Inorganic particle analysis of dental impression elastomers.

PubMed

Carlo, Hugo Lemes; Fonseca, Rodrigo Borges; Soares, Carlos José; Correr, Américo Bortolazzo; Correr-Sobrinho, Lourenço; Sinhoreti, Mário Alexandre Coelho

2010-01-01

The aim of this study was to determine quantitatively and qualitatively the inorganic particle fraction of commercially available dental elastomers. The inorganic volumetric fraction of two addition silicones (Reprosil Putty/Fluid and Flexitime Easy Putty/Fluid), three condensation silicones (Clonage Putty/Fluid, Optosil Confort/Xantopren VL and Silon APS Putty/Fluid), one polyether (Impregum Soft Light Body) and one polysulfide (Permlastic Light Body) was accessed by weighing a previously determined mass of each material in water before and after burning samples at 600 ºC, during 3 h. Unsettled material samples were soaked in acetone and chloroform for removal of the organic portion. The remaining filler particles were sputter-coated with gold evaluation of their morphology and size, under scanning electron microscopy (SEM). Flexitime Easy Putty was the material with the highest results for volumetric particle fraction, while Impregum Soft had the lowest values. Silon 2 APS Fluid presented the lowest mean filler size values, while Clonage Putty had the highest values. SEM micrographs of the inorganic particles showed several morphologies - lathe-cut, spherical, spherical-like, sticks, and sticks mixed to lathe-cut powder. The results of this study revealed differences in particle characteristics among the elastometic materials that could lead to different results when testing mechanical properties.

Effects of (Ce, Cu) Co-doping on the Structural and Optical Properties of ZnO Aerogels Synthesized in Supercritical Ethanol

NASA Astrophysics Data System (ADS)

Djouadi, D.; Slimi, O.; Hammiche, L.; Chelouche, A.; Touam, T.

2018-03-01

Undoped, Ce-doped, Cu-doped and (Ce,Cu ) co-doped ZnO aerogels were synthesized by sol-gel process in supercritical conditions of ethanol. [Cu]/[Zn] and [Ce]/[Zn] atomic ratios were fixed at 0.02 (2%). The aerogels were investigated without any additional treatments by using X-ray diffraction (XRD), UV–visible spectrophotometry, scanning electron microscopy (SEM), Energy-dispersive X-ray spectroscopy (EDS), Fourier transforms infrared spectroscopy (FTIR) and photoluminescence spectroscopy (PL). XRD results revealed that all the samples are well crystallized in hexagonal wurtzite structure. EDS measurements showed that highly pure aerogels are prepared. SEM analysis indicated that the morphology of the samples is dependent on Cu and Ce dopants. From UV-visible spectroscopy analyses, it was shown that the absorption and the band gap of the aerogels are strongly affected by Ce and Cu dopants. FTIR spectra demonstrated that co-doping induces a shift of Zn-O bond vibration band toward low wavenumbers. The room temperature photoluminescence spectra put into evidence that the visible emission intensity is influenced by Ce and Cu doping. In particular, the co-doping leads to the appearance of a blue emission band at 443 nm.

Antimicrobial and Antiproliferative Potential of Anadenanthera colubrina (Vell.) Brenan

PubMed Central

Lima, Rennaly de Freitas; Alves, Érika Ponchet; Rosalen, Pedro Luiz; Ruiz, Ana Lúcia Tasca Gois; Teixeira Duarte, Marta Cristina; Góes, Vivian Fernandes Furletti; de Medeiros, Ana Cláudia Dantas; Pereira, Jozinete Vieira; Godoy, Gustavo Pina; Melo de Brito Costa, Edja Maria

2014-01-01

The aim of the present study was to perform an in vitro analysis of the antimicrobial and antiproliferative potential of an extract from Anadenanthera colubrina (Vell.) Brenan (angico) and chemically characterize the crude extract. Antimicrobial action was evaluated based on the minimum inhibitory concentration (MIC), minimum bactericidal/fungicidal concentration, and the inhibition of formation to oral biofilm. Cell morphology was determined through scanning electron microscopy (SEM). Six strains of tumor cells were used for the determination of antiproliferative potential. The extract demonstrated strong antifungal activity against Candida albicans ATCC 18804 (MIC = 0.031 mg/mL), with similar activity found regarding the ethyl acetate fraction. The extract and active fraction also demonstrated the capacity to inhibit the formation of Candida albicans to oral biofilm after 48 hours, with median values equal to or greater than the control group, but the difference did not achieve statistical significance (P > 0.05). SEM revealed alterations in the cell morphology of the yeast. Regarding antiproliferative activity, the extract demonstrated cytostatic potential in all strains tested. The present findings suggest strong antifungal potential for Anadenanthera colubrina (Vell.) Brenan as well as a tendency toward diminishing the growth of human tumor cells. PMID:25093029

Transformation of toxic and allelopathic lantana into a benign organic fertilizer through vermicomposting

NASA Astrophysics Data System (ADS)

Hussain, Naseer; Abbasi, Tasneem; Abbasi, S. A.

2016-06-01

In a first study of its kind, the composition of vermicompost derived solely from the toxic and allelopathic weed lantana has been investigated using UV-visible and Fourier transform infrared (FT-IR) spectroscopy, thermogravimetric (TG) and differential scanning calorimetry (DSC), gas chromatography-mass spectometry (GC-MS), and scanning electron microscopy (SEM). The studies reveal that a sharp reduction in humification index, substantial mineralization of organic matter and degradation of complex aromatics such as lignin and polyphenols into simpler carbohydrates and lipids occur in the course of vermicomposting. GC-MS analysis shows significant fragmentation, bio-oxidation and molecular rearrangements of chemical compounds in vermicompost in comparison to those in lantana. SEM micrographs of vermicompost reflect strong disaggregation of material compared to the much better formed lantana matrices. The phenols and sesquiterpene lactones which are specifically responsible for the toxicity and allelopathy of lantana are seen to get significantly degraded in the course of vermicomposting - turning it into a plant-friendly organic fertilizer. The study leads to the possibility that the millions of tons of phytomass that is generated annually by lantana can be gainfully utilized in producing organic fertilizer via vermicomposting.

Observation of triple helix motif on electrospun collagen nanofibers and its effect on the physical and structural properties

NASA Astrophysics Data System (ADS)

Bürck, Jochen; Aras, Onur; Bertinetti, Luca; Ilhan, Caner A.; Ermeydan, Mahmut A.; Schneider, Reinhard; Ulrich, Anne S.; Kazanci, Murat

2018-01-01

Collagen is a very popular natural biomaterial due to its high biocompatibility and bioactivity. Electrospinning is currently the only technique that allows the fabrication of continuous fibers with diameters down to a few nanometers. In order to regenerate collagen in the forms of nanofibers, it is necessary to dissolve it in suitable solvents. The solvents and electrospinning process cause unfolding of collagen nanofibers. It is proposed that acidic solvents preserve better the natural structure of collagen fibers. In this paper, the structures of collagen nanofibers were examined by using circular dichroism (CD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), Raman spectroscopy, differential scanning calorimetry (DSC) and sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) methods in order to test this hypothesis. The increase in PP-II fraction, representing the triple helix structure in collagen, that was observed in CD analysis of HAc derived collagen nanofibers, for the first time was successfully confirmed and illustrated by using SEM and TEM methods. Furthermore, CD revealed the mostly detrimental effect of stabilization conditions such as heat, vacuum and UV treatment on the secondary structure of the collagen nanofibers.

Decontamination methods using a dental water jet and dental floss for microthreaded implant fixtures in regenerative periimplantitis treatment.

PubMed

Park, Shin-Young; Kim, Kyoung-Hwa; Shin, Seung-Yun; Koo, Ki-Tae; Lee, Yong-Moo; Chung, Chong-Pyoung; Seol, Yang-Jo

2015-06-01

This study evaluated decontamination methods using a dental water jet and dental floss on microthreaded implants for regenerative periimplantitis therapy. In 6 beagle dogs, experimental periimplantitis was induced, and decontamination procedures, including manual saline irrigation (control group), saline irrigation using a dental water jet (group 1) and saline irrigation using a dental water jet with dental flossing (group 2), were performed. After in situ decontamination procedures, some of the implant fixtures (n = 4 per group) were retrieved for analysis by SEM, whereas other fixtures (n = 4 per group) underwent regenerative therapy. After 3 months of healing, the animals were killed. The SEM examination indicated that decontamination of the implant surfaces was the most effective in group 2, with no changes in implant surface morphology. The histological examination also revealed that group 2 achieved significantly greater amounts of newly formed bone (6.75 ± 2.19 mm; P = 0.018), reosseointegration (1.88 ± 1.79 mm; P = 0.038), and vertical bone fill (26.69 ± 18.42%; P = 0.039). Decontamination using a dental water jet and dental floss on microthreaded implants showed positive mechanical debridement effects and positive bone regeneration effects.

Efficacy of atmospheric pressure dielectric barrier discharge for inactivating airborne pathogens

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

Romero-Mangado, Jaione; Dey, Avishek; Diaz-Cartagena, Diana C.

Atmospheric pressure plasmas have gained attention in recent years for several environmental applications. This technology could potentially be used to deactivate airborne microorganisms, surface-bound microorganisms, and biofilms. Here, the authors explore the efficacy of the atmospheric pressure dielectric barrier discharge (DBD) to inactivate airborne Staphylococcus epidermidis and Aspergillus niger that are opportunistic pathogens associated with nosocomial infections. This technology uses air as the source of gas and does not require any process gas such as helium, argon, nitrogen, or hydrogen. Moreover, the effect of DBD was studied on aerosolized S. epidermidis and aerosolized A. niger spores via scanning electron microscopymore » (SEM). The morphology observed on the SEM micrographs showed deformations in the cellular structure of both microorganisms. Cell structure damage upon interaction with the DBD suggests leakage of vital cellular materials, which is a key mechanism for microbial inactivation. The chemical structure of the cell surface of S. epidermidis was also analyzed by near edge x-ray absorption fine structure spectroscopy before and after DBD exposure. Our results from surface analysis revealed that reactive oxygen species from the DBD discharge contributed to alterations on the chemistry of the cell membrane/cell wall of S. epidermidis.« less

Synthesis and characterization of polyurethane/CdS-SiO 2 nanocomposites via ultrasonic process

NASA Astrophysics Data System (ADS)

Chen, Jing; Zhou, Yu-Ming; Nan, Qiu-Li; Ye, Xiao-Yun; Sun, Yan-Qing; Wang, Zhi-Qiang; Zhang, Shi-Ming

2008-12-01

In this study, the high-intensity ultrasound was applied in the preparation of chiral polyurethane/CdS-SiO 2 nanocomposites. The polyurethane/CdS-SiO 2 nanocomposites were analyzed by powder X-ray diffraction, thermogravimetric analysis (TGA), TEM and SEM. The results indicated that the heat stability of the nanocomposites was improved in the presence of CdS-SiO 2 core-shell nanoparticles. The infrared emissivity (8-14 μm) study revealed that the nanocomposites possessed much lower infrared values compared with those of the neat polymers and nanoparticles, respectively. A possible mechanism of ultrasonic induced composite reaction was proposed based on the experimental results.

Fractography used with lifetime prediction tests on commercial grades of alumina and silicon carbide

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

Kuebler, J.; Woodtli, J.; Berroth, K.

1996-12-31

Fractographic investigations were conducted on alumina and {alpha}-SSiC bend bars from a round robin test comparing a static and a dynamic lifetime test method. The investigations revealed that not all fracture origins found on {alpha}-SSiC specimens had contact with the ambient medium and therefore the dynamic lifetime tests did not measure the materials` behaviour under stress in water. In addition to the conventional SEM fractography an alternate technique, using an auto focus scanning laser profilometer was applied for characterizing the fractures. This tool is very promising for fractography because of the ability to handle topographic data by imaging procedures andmore » fractal analysis.« less

Examination of femtosecond laser matter interaction in multipulse regime for surface nanopatterning of vitreous substrates.

PubMed

Varkentina, Nadezda; Cardinal, Thierry; Moroté, Fabien; Mounaix, Patrick; André, Pascal; Deshayes, Yannick; Canioni, Lionel

2013-12-02

The paper presents our results on laser micro- and nanostructuring of sodium aluminosilicate glass for the permanent storage purposes and photonics applications. Surface structuring is realized by fs laser irradiation followed by the subsequent etching in a potassium hydroxide (10M@80 °C) for 1 to 10 minutes. As the energy deposited is lower than the damage and/or ablation threshold, the chemical etching permits to produce small craters in the laser modified region. The laser parameters dependent interaction regimes are revealed by microscopic analysis (SEM and AFM). The influence of etching time on craters formation is investigated under different incident energies, number of pulses and polarization states.

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.

Synthesis, structural and vibrational studies on mixed alkali metal gadolinium double tungstate, K1-xNaxGd(WO4)2

NASA Astrophysics Data System (ADS)

Durairajan, A.; Thangaraju, D.; Moorthy Babu, S.

2013-02-01

Mixed alkali double tungstates K1-xNaxGd(WO4)2 (KNGW) (0 ⩽ x ⩽ 1) were synthesized by solid state reaction using sodium doped monoclinic KGd(WO4)2 (KGW). Synthesized KNGW powders were characterized using powder X-ray diffraction (XRD), differential thermal analysis (DTA), scanning electron microscopy (SEM) and Raman analysis. DTA analysis confirms that the melting point of the KGW matrix increases from 1063 °C to 1255 °C with increasing sodium content. The Powder XRD analyses reveal that mixed phases were observed up to 40 wt.% of Na in the KGW matrix above that percentage there is domination of scheelite structure in the synthesized powder. Polyhedral type, bi-pyramidal shape and spheroid shape morphology was observed for KGW, NKGW and NGW powders respectively. The Raman analysis was carried out to understand the vibrational characteristic changes with mixing of sodium ions in the KGW matrix.

Framework for SEM contour analysis

NASA Astrophysics Data System (ADS)

Schneider, L.; Farys, V.; Serret, E.; Fenouillet-Beranger, C.

2017-03-01

SEM images provide valuable information about patterning capability. Geometrical properties such as Critical Dimension (CD) can be extracted from them and are used to calibrate OPC models, thus making OPC more robust and reliable. However, there is currently a shortage of appropriate metrology tools to inspect complex two-dimensional patterns in the same way as one would work with simple one-dimensional patterns. In this article we present a full framework for the analysis of SEM images. It has been proven to be fast, reliable and robust for every type of structure, and particularly for two-dimensional structures. To achieve this result, several innovative solutions have been developed and will be presented in the following pages. Firstly, we will present a new noise filter which is used to reduce noise on SEM images, followed by an efficient topography identifier, and finally we will describe the use of a topological skeleton as a measurement tool that can extend CD measurements on all kinds of patterns.

Electrophoretic fabrication of chitosan-zirconium-oxide nanobiocomposite platform for nucleic acid detection.

PubMed

Das, Maumita; Dhand, Chetna; Sumana, Gajjala; Srivastava, A K; Nagarajan, R; Nain, Lata; Iwamoto, M; Manaka, Takaaki; Malhotra, B D

2011-03-14

The present work describes electrophoretic fabrication of nanostructured chitosan-zirconium-oxide composite (CHIT-NanoZrO(2)) film (180 nm) onto indium-tin-oxide (ITO)-coated glass plate. This nanobiocomposite film has been explored as immobilization platform for probe DNA specific to M. Tuberculosis as model biomolecule to investigate its sensing characteristics. It is revealed that pH-responsive behavior of CHIT and its cationic skeleton is responsible for the movement of CHIT-NanoZrO(2) colloids toward cathode during electrophoretic deposition. The FT-IR, SEM, TEM, and EDX techniques have been employed for the structural, morphological, and composition analysis of the fabricated electrodes. The morphological studies clearly reveal uniform inter-linking and dispersion of hexagonal nanograins of ZrO(2) (30-50 nm) into the chitosan matrix, resulting in homogeneous nanobiocomposite formation. Electrochemical response measurements of DNA/CHIT-NanoZrO(2)/ITO bioelectrode, carried out using cyclic voltammetry and differential pulse voltammetry, reveal that this bioelectrode can specifically detect complementary target DNA up to 0.00078 μM with sensitivity of 6.38 × 10(-6) AμM(-1).

High resolution electrolyte for thinning InP by anodic dissolution and its applications to EC-V profiling, defect revealing and surface passivation

NASA Technical Reports Server (NTRS)

Faur, Maria; Faur, Mircea; Weinberg, Irving; Goradia, Manju; Vargas, Carlos

1991-01-01

An extensive experimental study was conducted using various electrolytes in an effort to find an appropriate electrolyte for anodic dissolution of InP. From the analysis of electrochemical characteristics in the dark and under different illumination levels, x ray photoelectron spectroscopy and SEM/Nomarski inspection of the surfaces, it was determined that the anodic dissolution of InP front surface layers by FAP electrolyte is a very good choice for rendering smooth surfaces, free of oxides and contaminants and with good electrical characteristics. The FAP electrolyte, based on HF, CH3COOH, and H2O2 appears to be inherently superior to previously reported electrolytes for performing accurate EC-V profiling of InP at current densities of up to 0.3 mA/sq cm. It can also be used for accurate electrochemical revealing of either precipitates or dislocation density with application to EPD mapping as a function of depth, and for defect revealing of multilayer InP structures at any depth and/or at the interfaces.

SEM AutoAnalysis: enhancing photomask and NIL defect disposition and review

NASA Astrophysics Data System (ADS)

Schulz, Kristian; Egodage, Kokila; Tabbone, Gilles; Ehrlich, Christian; Garetto, Anthony

2017-06-01

For defect disposition and repair verification regarding printability, AIMS™ is the state of the art measurement tool in industry. With its unique capability of capturing aerial images of photomasks it is the one method that comes closest to emulating the printing behaviour of a scanner. However for nanoimprint lithography (NIL) templates aerial images cannot be applied to evaluate the success of a repair process. Hence, for NIL defect dispositioning scanning, electron microscopy (SEM) imaging is the method of choice. In addition, it has been a standard imaging method for further root cause analysis of defects and defect review on optical photomasks which enables 2D or even 3D mask profiling at high resolutions. In recent years a trend observed in mask shops has been the automation of processes that traditionally were driven by operators. This of course has brought many advantages one of which is freeing cost intensive labour from conducting repetitive and tedious work. Furthermore, it reduces variability in processes due to different operator skill and experience levels which at the end contributes to eliminating the human factor. Taking these factors into consideration, one of the software based solutions available under the FAVOR® brand to support customer needs is the aerial image evaluation software, AIMS™ AutoAnalysis (AAA). It provides fully automated analysis of AIMS™ images and runs in parallel to measurements. This is enabled by its direct connection and communication with the AIMS™tools. As one of many positive outcomes, generating automated result reports is facilitated, standardizing the mask manufacturing workflow. Today, AAA has been successfully introduced into production at multiple customers and is supporting the workflow as described above. These trends indeed have triggered the demand for similar automation with respect to SEM measurements leading to the development of SEM AutoAnalysis (SAA). It aims towards a fully automated SEM image evaluation process utilizing a completely different algorithm due to the different nature of SEM images and aerial images. Both AAA and SAA are the building blocks towards an image evaluation suite in the mask shop industry.

Quantitative Determination of Noa (Naturally Occurring Asbestos) in Rocks : Comparison Between Pcom and SEM Analysis

NASA Astrophysics Data System (ADS)

Baietto, Oliviero; Amodeo, Francesco; Giorgis, Ilaria; Vitaliti, Martina

2017-04-01

The quantification of NOA (Naturally Occurring Asbestos) in a rock or soil matrix is complex and subject to numerous errors. The purpose of this study is to compare two fundamental methodologies used for the analysis: the first one uses Phase Contrast Optical Microscope (PCOM) while the second one uses Scanning Electron Microscope (SEM). The two methods, although they provide the same result, which is the asbestos mass to total mass ratio, have completely different characteristics and both present pros and cons. The current legislation in Italy involves the use of SEM, DRX, FTIR, PCOM (DM 6/9/94) for the quantification of asbestos in bulk materials and soils and the threshold beyond which the material is considered as hazardous waste is a concentration of asbestos fiber of 1000 mg/kg.(DM 161/2012). The most used technology is the SEM which is the one among these with the better analytical sensitivity.(120mg/Kg DM 6 /9/94) The fundamental differences among the analyses are mainly: - Amount of analyzed sample portion - Representativeness of the sample - Resolution - Analytical precision - Uncertainty of the methodology - Operator errors Due to the problem of quantification of DRX and FTIR (1% DM 6/9/94) our Asbestos Laboratory (DIATI POLITO) since more than twenty years apply the PCOM methodology and in the last years the SEM methodology for quantification of asbestos content. The aim of our research is to compare the results obtained from a PCOM analysis with the results provided by SEM analysis on the base of more than 100 natural samples both from cores (tunnel-boring or explorative-drilling) and from tunnelling excavation . The results obtained show, in most cases, a good correlation between the two techniques. Of particular relevance is the fact that both techniques are reliable for very low quantities of asbestos, even lower than the analytical sensitivity. This work highlights the comparison between the two techniques emphasizing strengths and weaknesses of the two procedures and suggests how an integrated approach, together with the skills and experience of the operator may be the best way forward in order to obtain a constructive improvement of analysis techniques.

Three-dimensional characterization of pigment dispersion in dried paint films using focused ion beam-scanning electron microscopy.

PubMed

Lin, Jui-Ching; Heeschen, William; Reffner, John; Hook, John

2012-04-01

The combination of integrated focused ion beam-scanning electron microscope (FIB-SEM) serial sectioning and imaging techniques with image analysis provided quantitative characterization of three-dimensional (3D) pigment dispersion in dried paint films. The focused ion beam in a FIB-SEM dual beam system enables great control in slicing paints, and the sectioning process can be synchronized with SEM imaging providing high quality serial cross-section images for 3D reconstruction. Application of Euclidean distance map and ultimate eroded points image analysis methods can provide quantitative characterization of 3D particle distribution. It is concluded that 3D measurement of binder distribution in paints is effective to characterize the order of pigment dispersion in dried paint films.

Effects of subacute ingestion of chlorogenic acids on sleep architecture and energy metabolism through activity of the autonomic nervous system: a randomised, placebo-controlled, double-blinded cross-over trial.

PubMed

Park, Insung; Ochiai, Ryuji; Ogata, Hitomi; Kayaba, Momoko; Hari, Sayaka; Hibi, Masanobu; Katsuragi, Yoshihisa; Satoh, Makoto; Tokuyama, Kumpei

2017-04-01

Chlorogenic acids (CGA) are the most abundant polyphenols in coffee. Continuous consumption of CGA reduces body fat and body weight. Since energy metabolism and sleep are controlled by common regulatory factors, consumption of CGA might modulate sleep. Lack of sleep has been identified as a risk factor for obesity, hypertension and type 2 diabetes. The aim of this study was to determine the effects of ingesting CGA over 5 d on energy metabolism and sleep quality in humans. A total of nine healthy subjects (four male and five female) completed a placebo-controlled, double-blinded, cross-over intervention study. Subjects consumed a test beverage containing 0 or 600 mg of CGA for 5 d. On the fifth night, subjects stayed in a whole-room metabolic chamber to measure energy metabolism; sleep was evaluated using polysomnographic recording. It was found that CGA shortened sleep latency (9 (sem 2) v. 16 (sem 4) min, P<0·05) compared with the control, whereas no effect on sleep architecture, such as slow-wave sleep, rapid eye movement or waking after sleep onset, was observed. Indirect calorimetry revealed that consumption of CGA increased fat oxidation (510 (sem 84) kJ/8 h (122 (sem 20) kcal/8 h) v. 331 (sem 79) kJ/8 h (81 (sem 19) kcal/8 h), P<0·05) but did not affect energy expenditure during sleep. Consumption of CGA enhanced parasympathetic activity assessed from heart-rate variability during sleep (999 (sem 77) v. 919 (sem 54), P<0·05). A period of 5-d CGA consumption significantly increased fat oxidation during sleep, suggesting that beverages containing CGA may be beneficial to reduce body fat and prevent obesity. Consumption of CGA shortened sleep latency and did not adversely affect sleep quality.

Synthesis, physicochemical characterization, DFT calculation and biological activities of Fe(III) and Co(II)-omeprazole complexes. Potential application in the Helicobacter pylori eradication

NASA Astrophysics Data System (ADS)

Russo, Marcos G.; Vega Hissi, Esteban G.; Rizzi, Alberto C.; Brondino, Carlos D.; Salinas Ibañez, Ángel G.; Vega, Alba E.; Silva, Humberto J.; Mercader, Roberto; Narda, Griselda E.

2014-03-01

The reaction between the antiulcer agent omeprazole (OMZ) with Fe(III) and Co(II) ions was studied, observing a high ability to form metal complexes. The isolated microcrystalline solid complexes were characterized by elemental analysis, X-ray powder diffraction (XRPD), Scanning Electron Microscopy (SEM), magnetic measurements, thermal study, FTIR, UV-Visible, Mössbauer, electronic paramagnetic resonance (EPR), and DFT calculations. The metal-ligand ratio for both complexes was 1:2 determined by elemental and thermal analysis. FTIR spectroscopy showed that OMZ acts as a neutral bidentate ligand through the pyridinic nitrogen of the benzimidazole ring and the oxygen atom of the sulfoxide group, forming a five-membered ring chelate. Electronic, Mössbauer, and EPR spectra together with magnetic measurements indicate a distorted octahedral geometry around the metal ions, where the coordination sphere is completed by two water molecules. SEM and XRPD were used to characterize the morphology and the crystal nature of the complexes. The most favorable conformation for the Fe(III)-OMZ and Co(II)-OMZ complexes was obtained by DFT calculations by using B3LYP/6-31G(d)&LanL2DZ//B3LYP/3-21G(d)&LanL2DZ basis set. Studies of solubility along with the antibacterial activity against Helicobacter pylori for OMZ and its Co(II) and Fe(III) complexes are also reported. Free OMZ and both metal complexes showed antibacterial activity against H. pylori. Co(II)-OMZ presented a minimal inhibitory concentration ˜32 times lower than that of OMZ and ˜65 lower than Fe(III)-OMZ, revealing its promising potential use for the treatment of gastric pathologies associated with the Gram negative bacteria. The morphological changes observed in the cell membrane of the bacteria after the incubation with the metal-complexes were also analyzed by SEM microscopy. The antimicrobial activity of the complexes was proved by the viability test.

Novel class of collector in electrospinning device for the fabrication of 3D nanofibrous structure for large defect load-bearing tissue engineering application.

PubMed

Hejazi, Fatemeh; Mirzadeh, Hamid; Contessi, Nicola; Tanzi, Maria Cristina; Faré, Silvia

2017-05-01

Adequate porosity, appropriate pore size, and 3D-thick shape are crucial parameters in the design of scaffolds, as they should provide the right space for cell adhesion, spreading, migration, and growth. In this work, a novel design for fabricating a 3D nanostructured scaffold by electrospinning was taken into account. Helical spring-shaped collector was purposely designed and used for electrospinning PCL fibers. Improved morphological properties and more uniform diameter distribution of collected nanofibers on the turns of helical spring-shaped collector are confirmed by SEM analysis. SEM images elaboration showed 3D pores with average diameter of 4 and 5.5 micrometer in x-y plane and z-direction, respectively. Prepared 3D scaffold possessed 99.98% porosity which led to the increased water uptake behavior in PBS at 37°C up to 10 days, and higher degradation rate compared to 2D flat structure. Uniaxial compression test on 3D scaffolds revealed an elastic modulus of 7 MPa and a stiffness of 10 2 MPa, together with very low hysteresis area and residual strain. In vitro cytocompatibility test with MG-63 osteoblast-like cells using AlamarBlue ™ colorimetric assay, indicated a continuous increase in cell viability for the 3D structure over the test duration. SEM observation showed enhanced cells spreading and diffusion into the underneath layers for 3D scaffold. Accelerated calcium deposition in 3D substrate was confirmed by EDX analysis. Obtained morphological, physical, and mechanical properties together with in vitro cytocompatibility results, suggest this novel technique as a proper method for the fabrication of 3D nanofibrous scaffolds for the regeneration of critical-size load bearing defects. © 2017 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 105A: 1535-1548, 2017. © 2017 Wiley Periodicals, Inc.

Characterization of Chlorhexidine-Loaded Calcium-Hydroxide Microparticles as a Potential Dental Pulp-Capping Material.

PubMed

Priyadarshini, Balasankar M; Selvan, Subramanian T; Narayanan, Karthikeyan; Fawzy, Amr S

2017-06-22

This study explores the delivery of novel calcium hydroxide [Ca(OH)₂] microparticles loaded with chlorhexidine (CHX) for potential dental therapeutic and preventive applications. Herein, we introduce a new approach for drug-delivery to deep dentin-surfaces in the form of drug-loaded microparticles. Unloaded Ca(OH)₂ [Ca(OH)₂/Blank] and CHX-loaded/Ca(OH)₂ microparticles were fabricated by aqueous chemical-precipitation technique. The synthesized-microparticles were characterized in vitro for determination of surface-morphology, crystalline-features and thermal-properties examined by energy-dispersive X-ray scanning and transmission electron-microscopy (EDX-SEM/TEM), Fourier-transform infrared-spectroscopy (FTIR), X-ray diffraction (XRD), thermogravimetric analysis (TGA) and differential scanning-calorimetry (DSC). Time-related pH changes, initial antibacterial/biofilm-abilities and cytotoxicity of CHX-loaded/Ca(OH)₂ microparticles were evaluated. Microparticles were delivered to dentin-surfaces with subsequent SEM examination of treated dentin-substrates. The in vitro and ex vivo CHX-release profiles were characterized. Ca(OH)₂/Blank were hexagonal-shaped with highest z -average diameter whereas CHX-inclusion evidenced micro-metric spheres with distinguishable surface "rounded deposits" and a negative-shift in diameter. CHX:Ca(OH)₂/50 mg exhibited maximum encapsulation-efficiency with good antibacterial and cytocompatible properties. SEM examination revealed an intact layer of microparticles on exposed dentin-surfaces with retention of spherical shape and smooth texture. Microparticles loaded on dentin-surfaces showed prolonged release of CHX indicating substantial retention on dentin-substrates. This study validated the inherent-applicability of this novel drug-delivery approach to dentin-surfaces using micro-metric CHX-loaded/Ca(OH)₂ microparticles.

A Mössbauer spectral study of degradation in La 0.58Sr 0.4Fe 0.5Co 0.5O 3–x after long-term operation in solid oxide electrolysis cells

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

Mahmoud, Abdelfattah; Daroukh, Mahmoud Al; Lipinska-Chwalek, Marta

Here, degradation processes of oxygen electrodes in solid oxide electrolysis cells (SOECs) were studied by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and Mössbauer spectroscopy. La 0.58Sr 0.4Fe 0.5Co 0.5O 3–x (LSCF) anodes (oxygen electrode) were analyzed after different long-term operations durations of 1774, 6100 and 9000 h. The results were compared with a cell in the initial state. Besides the LSCF anode, the SOECs were composed of a Ce 0.8Gd 0.2O 1.9 barrier layer between the anode and electrolyte, yttria-stabilized zirconia (YSZ) as electrolyte and Ni-YSZ as cathode (hydrogen electrode). Mössbauer spectra of the iron-containingmore » anode were acquired in order to determine the alteration of the iron oxidation state and its local environment during operation. Mössbauer spectroscopy yields indirect information about the degradation mechanism, especially in combination with SEM, TEM, and XRD. XRD and TEM revealed the appearance of Co 3O 4 during the SOEC operation and SEM analyses confirmed the formation of SrZrO 3 at the electrode/electrolyte interface. The spectral analysis confirmed the reduction of iron from Fe(IV) to Fe(III) in LSCF after long-term operation. The fraction of Fe(IV) in the electrode decreased with time and 18, 15, 13 and 11% were obtained for 0, 1774, 6100, and 9000 h of operation, respectively.« less

A Mössbauer spectral study of degradation in La 0.58Sr 0.4Fe 0.5Co 0.5O 3–x after long-term operation in solid oxide electrolysis cells

DOE PAGES

Mahmoud, Abdelfattah; Daroukh, Mahmoud Al; Lipinska-Chwalek, Marta; ...

2017-10-21

Here, degradation processes of oxygen electrodes in solid oxide electrolysis cells (SOECs) were studied by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and Mössbauer spectroscopy. La 0.58Sr 0.4Fe 0.5Co 0.5O 3–x (LSCF) anodes (oxygen electrode) were analyzed after different long-term operations durations of 1774, 6100 and 9000 h. The results were compared with a cell in the initial state. Besides the LSCF anode, the SOECs were composed of a Ce 0.8Gd 0.2O 1.9 barrier layer between the anode and electrolyte, yttria-stabilized zirconia (YSZ) as electrolyte and Ni-YSZ as cathode (hydrogen electrode). Mössbauer spectra of the iron-containingmore » anode were acquired in order to determine the alteration of the iron oxidation state and its local environment during operation. Mössbauer spectroscopy yields indirect information about the degradation mechanism, especially in combination with SEM, TEM, and XRD. XRD and TEM revealed the appearance of Co 3O 4 during the SOEC operation and SEM analyses confirmed the formation of SrZrO 3 at the electrode/electrolyte interface. The spectral analysis confirmed the reduction of iron from Fe(IV) to Fe(III) in LSCF after long-term operation. The fraction of Fe(IV) in the electrode decreased with time and 18, 15, 13 and 11% were obtained for 0, 1774, 6100, and 9000 h of operation, respectively.« less

Kinetics of apatite formation on a calcium-silicate cement for root-end filling during ageing in physiological-like phosphate solutions.

PubMed

Gandolfi, Maria Giovanna; Taddei, Paola; Tinti, Anna; De Stefano Dorigo, Elettra; Rossi, Piermaria Luigi; Prati, Carlo

2010-12-01

The bioactivity of calcium silicate mineral trioxide aggregate (MTA) cements has been attributed to their ability to produce apatite in presence of phosphate-containing fluids. This study evaluated surface morphology and chemical transformations of an experimental accelerated calcium-silicate cement as a function of soaking time in different phosphate-containing solutions. Cement discs were immersed in Dulbecco's phosphate-buffered saline (DPBS) or Hank's balanced salt solution (HBSS) for different times (1-180 days) and analysed by scanning electron microscopy connected with an energy dispersive X-ray analysis (SEM-EDX) and micro-Raman spectroscopy. SEM-EDX revealed Ca and P peaks after 14 days in DPBS. A thin Ca- and P-rich crystalline coating layer was detected after 60 days. A thicker multilayered coating was observed after 180 days. Micro-Raman disclosed the 965-cm(-1) phosphate band at 7 days only on samples stored in DPBS and later the 590- and 435-cm(-1) phosphate bands. After 60-180 days, a layer approximately 200-900 μm thick formed displaying the bands of carbonated apatite (at 1,077, 965, 590, 435 cm(-1)) and calcite (at 1,088, 713, 280 cm(-1)). On HBSS-soaked, only calcite bands were observed until 90 days, and just after 180 days, a thin apatite-calcite layer appeared. Micro-Raman and SEM-EDX demonstrated the mineralization induction capacity of calcium-silicate cements (MTAs and Portland cements) with the formation of apatite after 7 days in DPBS. Longer time is necessary to observe bioactivity when cements are immersed in HBSS.

Geochemical characteristics of Au in the water systemfrom abandoned gold mines area

NASA Astrophysics Data System (ADS)

Cho, Kanghee; Kim, Bongju; Kim, Byungjoo; Park, Cheonyoung; Choi, Nagchoul

2013-04-01

The AMD (acid mine drainage) poses a threat not only to the aquatic life in mountain streams and rivers, but can also contaminate groundwater and downstream water bodies. Besides pyrite, sulfides of copper, zinc, cadmium, lead and arsenic in the drainage tunnels and tailings piles also undergo similar geochemical reactions, releasing toxic metals and more H+ into the mine drainage. The fate of gold in the AMD system is reduced and precipitated with iron oxides by oxidation-reduction reaction between ferrous/ferric iron and Au3+/Au0. The objective of this study was to investigate the influence of the transport characteristic on the distance through distribution of heavy metals and gold on the interrelation between acid mine drainage and sediments in the abandoned Gwang-yang gold mine, Korea. We conducted to confirm the chemical (chemical analysis and sequential extraction) and mineralogical property (XRD, SEM-EDS and polarization microscope) from AMD, sediments and tailing samples. The result of chemical analysis showed that Fe contents in the AMD and sediments from the upstream to the downstream ranged of 10.99 to 18.60 mg/L and 478.74 to 542.98 mg/kg, respectively. Also the contents of Au and As in the sediment were respectively ranged from 14.06 to 22.85 g/t and 0.245 to 0.612 mg/kg. In XRD analysis of the sediments, x-ray diffracted d-value belong to quartz, geothite was observed. The results of SEM-EDS analysis revealed that iron hydroxide were observed in the sediment and tailing. The result of sequential extraction for Au from the sediment showed that Au predominated in 26 to 27% of Organic matter fraction(STEP 4), and 24 to 25% of Residual fraction(STEP 5).

Characterization of prepared In2O3 thin films: The FT-IR, FT-Raman, UV-Visible investigation and optical analysis.

PubMed

Panneerdoss, I Joseph; Jeyakumar, S Johnson; Ramalingam, S; Jothibas, M

2015-08-05

In this original work, the Indium oxide (In2O3) thin film is deposited cleanly on microscope glass substrate at different temperatures by spray pyrolysis technique. The physical properties of the films are characterized by XRD, SEM, AFM and AFM measurements. The spectroscopic investigation has been carried out on the results of FT-IR, FT-Raman and UV-Visible. XRD analysis exposed that the structural transformation of films from stoichiometric to non-stoichiometric orientation of the plane vice versa and also found that, the film is polycrystalline in nature having cubic crystal structure with a preferred grain orientation along (222) plane. SEM and AFM studies revealed that, the film with 0.1M at 500°C has spherical grains with uniform dimension. The complete vibrational analysis has been carried out and the optimized parameters are calculated using HF and DFT (CAM-B3LYP, B3LYP and B3PW91) methods with 3-21G(d,p) basis set. Furthermore, NMR chemical shifts are calculated by using the gauge independent atomic orbital (GIAO) technique. The molecular electronic properties; absorption wavelengths, excitation energy, dipole moment and frontier molecular orbital energies, molecular electrostatic potential energy (MEP) analysis and Polarizability first order hyperpolarizability calculations are performed by time dependent DFT (TD-DFT) approach. The energy excitation on electronic structure is investigated and the assignment of the absorption bands in the electronic spectra of steady compound is discussed. The calculated HOMO and LUMO energies showed the enhancement of energy gap by the addition of substitutions with the base molecule. The thermodynamic properties (heat capacity, entropy, and enthalpy) at different temperatures are calculated and interpreted in gas phase. Crown Copyright © 2015. Published by Elsevier B.V. All rights reserved.

Evaluation of ionic degradation and slot corrosion of metallic brackets by the action of different dentifrices.

PubMed

Brandão, Gustavo Antônio Martins; Simas, Rafael Menezes; de Almeida, Leandro Moreira; da Silva, Juliana Melo; Meneghim, Marcelo de Castro; Pereira, Antonio Carlos; de Almeida, Haroldo Amorim; Brandão, Ana Maria Martins

2013-01-01

To evaluate the in vitro ionic degradation and slot base corrosion of metallic brackets subjected to brushing with dentifrices, through analysis of chemical composition by Energy Dispersive Spectroscopy (EDS) and qualitative analysis by Scanning Electron Microscopy (SEM). Thirty eight brackets were selected and randomly divided into four experimental groups (n = 7). Two groups (n = 5) worked as positive and negative controls. Simulated orthodontic braces were assembled using 0.019 x 0.025-in stainless steel wires and elastomeric rings. The groups were divided according to surface treatment: G1 (Máxima Proteção Anticáries®); G2 (Total 12®); G3 (Sensitive®); G4 (Branqueador®); Positive control (artificial saliva) and Negative control (no treatment). Twenty eight brushing cycles were performed and evaluations were made before (T0) and after (T1) experiment. The Wilcoxon test showed no difference in ionic concentrations of titanium (Ti), chromium (Cr), iron (Fe) and nickel (Ni) between groups. G2 presented significant reduction (p < 0.05) in the concentration of aluminium ion (Al). Groups G3 and G4 presented significant increase (p < 0.05) in the concentration of aluminium ion. The SEM analysis showed increased characteristics indicative of corrosion on groups G2, G3 and G4. The EDS analysis revealed that control groups and G1 did not suffer alterations on the chemical composition. G2 presented degradation in the amount of Al ion. G3 and G4 suffered increase in the concentration of Al. The immersion in artificial saliva and the dentifrice Máxima Proteção Anticáries® did not alter the surface polishing. The dentifrices Total 12®, Sensitive® and Branqueador® altered the surface polishing.

An investigation of adhesive/adherend and fiber/matrix interactions. Part B: SEM/ESCA analysis of fracture surfaces

NASA Technical Reports Server (NTRS)

Beck, B.; Widyani, E.; Wightman, J. P.

1983-01-01

Adhesion was studied with emphasis on the characterization of surface oxide layers, the analysis of fracture surfaces, and the interaction of matrices and fibers. A number of surface features of the fractured lap shear samples were noted in the SEM photomicrographs including the beta phase alloy of the Ti 6-4 adherend, the imprint of the adherend on the adhesive failure surface, increased void density for high temperature samples, and the alumina filler particles. Interfacial failure of some of the fractured lap shear samples is invariably characterized by the appearance of an ESCA oxygen photopeak at 530.3 eV assigned to the surface oxide layer of Ti 6-4 adherend. The effect of grit blasting on carbon fiber composites is evident in the SEM analysis. A high surface fluorine concentration on the composite surface is reduced some ten fold by grit blasting.

Physicochemical and microscopic characterization of implant–abutment joints

PubMed Central

Lopes, Patricia A.; Carreiro, Adriana F. P.; Nascimento, Rubens M.; Vahey, Brendan R.; Henriques, Bruno; Souza, Júlio C. M.

2018-01-01

Objective: The purpose of this study was to investigate Morse taper implant–abutment joints by chemical, mechanical, and microscopic analysis. Materials and Methods: Surfaces of 10 Morse taper implants and the correlated abutments were inspected by field emission gun-scanning electron microscopy (FEG-SEM) before connection. The implant–abutment connections were tightened at 32 Ncm. For microgap evaluation by FEG-SEM, the systems were embedded in epoxy resin and cross-sectioned at a perpendicular plane of the implant–abutment joint. Furthermore, nanoindentation tests and chemical analysis were performed at the implant–abutment joints. Statistics: Results were statistically analyzed via one-way analysis of variance, with a significance level of P < 0.05. Results: Defects were noticed on different areas of the abutment surfaces. The minimum and maximum size of microgaps ranged from 0.5 μm up to 5.6 μm. Furthermore, defects were detected throughout the implant–abutment joint that can, ultimately, affect the microgap size after connection. Nanoindentation tests revealed a higher hardness (4.2 ± 0.4 GPa) for abutment composed of Ti6Al4V alloy when compared to implant composed of commercially pure Grade 4 titanium (3.2 ± 0.4 GPa). Conclusions: Surface defects produced during the machining of both implants and abutments can increase the size of microgaps and promote a misfit of implant–abutment joints. In addition, the mismatch in mechanical properties between abutment and implant can promote the wear of surfaces, affecting the size of microgaps and consequently the performance of the joints during mastication. PMID:29657532

Evaluation of experimental coating to improve the zirconia-veneering ceramic bond strength.

PubMed

Matani, Jay D; Kheur, Mohit; Jambhekar, Shantanu Subhashchandra; Bhargava, Parag; Londhe, Aditya

2014-12-01

To evaluate the shear bond strength (SBS) between zirconia and veneering ceramic following different surface treatments of zirconia. The efficacy of an experimental zirconia coating to improve the bond strength was also evaluated. Zirconia strips were fabricated and were divided into four groups as per their surface treatment: polished (control), airborne-particle abrasion, laser irradiation, and application of the experimental coating. The surface roughness and the residual monoclinic content were evaluated before and after the respective surface treatments. A scanning electron microscope (SEM) analysis of the experimental surfaces was performed. All specimens were subjected to shear force in a universal testing machine. The SBS values were analyzed with one-way ANOVA followed by Bonferroni post hoc for groupwise comparisons. The fractured specimens were examined to observe the failure mode. The SBS (29.17 MPa) and roughness values (0.80) of the experimental coating group were the highest among the groups. The residual monoclinic content was minimal (0.32) when compared to the remaining test groups. SEM analysis revealed a homogenous surface well adhered to an undamaged zirconia base. The other test groups showed destruction of the zirconia surface. The analysis of failure following bond strength testing showed entirely cohesive failures in the veneering ceramic in all study groups. The experimental zirconia surface coating is a simple technique to increase the microroughness of the zirconia surface, and thereby improve the SBS to the veneering ceramic. It results in the least monoclinic content and produces no structural damage to the zirconia substructure. © 2014 by the American College of Prosthodontists.

Comparison of methods for the analysis of relatively simple mediation models.

PubMed

Rijnhart, Judith J M; Twisk, Jos W R; Chinapaw, Mai J M; de Boer, Michiel R; Heymans, Martijn W

2017-09-01

Statistical mediation analysis is an often used method in trials, to unravel the pathways underlying the effect of an intervention on a particular outcome variable. Throughout the years, several methods have been proposed, such as ordinary least square (OLS) regression, structural equation modeling (SEM), and the potential outcomes framework. Most applied researchers do not know that these methods are mathematically equivalent when applied to mediation models with a continuous mediator and outcome variable. Therefore, the aim of this paper was to demonstrate the similarities between OLS regression, SEM, and the potential outcomes framework in three mediation models: 1) a crude model, 2) a confounder-adjusted model, and 3) a model with an interaction term for exposure-mediator interaction. Secondary data analysis of a randomized controlled trial that included 546 schoolchildren. In our data example, the mediator and outcome variable were both continuous. We compared the estimates of the total, direct and indirect effects, proportion mediated, and 95% confidence intervals (CIs) for the indirect effect across OLS regression, SEM, and the potential outcomes framework. OLS regression, SEM, and the potential outcomes framework yielded the same effect estimates in the crude mediation model, the confounder-adjusted mediation model, and the mediation model with an interaction term for exposure-mediator interaction. Since OLS regression, SEM, and the potential outcomes framework yield the same results in three mediation models with a continuous mediator and outcome variable, researchers can continue using the method that is most convenient to them.

Building a SEM Analytics Reporting Portfolio

ERIC Educational Resources Information Center

Goff, Jay W.; Williams, Brian G.; Kilgore, Wendy

2016-01-01

Effective strategic enrollment management (SEM) efforts require vast amounts of internal and external data to ensure that meaningful reporting and analysis systems can assist managers in decision making. A wide range of information is integral for leading effective and efficient student recruitment and retention programs. This article is designed…

GUIDELINES FOR THE APPLICATION OF SEM/EDX ANALYTICAL TECHNIQUES FOR FINE AND COARSE PM SAMPLES

EPA Science Inventory

Scanning Electron Microscopy (SEM) coupled with Energy-Dispersive X-ray analysis (EDX) is a powerful tool in the characterization and source apportionment of environmental particulate matter (PM), providing size, chemistry, and morphology of particles as small as a few tenths ...

Oral astringent stimuli alter the enamel pellicle's ultrastructure as revealed by electron microscopy.

PubMed

Rehage, Melanie; Delius, Judith; Hofmann, Thomas; Hannig, Matthias

2017-08-01

This electron microscopic study aimed at investigating effects of oral astringent stimuli on the enamel pellicle's morphology. Pellicles were formed in situ within 30min on bovine enamel slabs, fixed to individuals' upper jaw splints. The pellicle-coated specimens were immersed in vitro in seven diverse astringent solutions and subsequently analyzed by scanning electron microscopy (SEM), energy dispersive X-ray (EDX) spectroscopy, as well as transmission electron microscopy (TEM). Four biocompatible astringents, namely the polyphenol epigallocatechin gallate, the metal salt iron(III) sulfate, the basic protein lysozyme, and the aminopolysaccharide chitosan, were additionally applied in situ. After rinsing the oral cavity with these compounds, the pellicle's ultrastructure was imaged by SEM and TEM, respectively. Untreated pellicle samples served as controls. Exposure to polyphenols and lysozyme induced particularly thicker and electron-denser pellicles in comparison to the control pellicle with similar characteristics in vitro and in situ. In contrast, acidic chitosan and metal salt solutions, respectively, revealed minor pellicle alterations. The incorporation of Fe and Al into the pellicles treated with the corresponding inorganic salts was verified by EDX analysis. Astringent-induced pellicle modifications were for the first time visualized by TEM. The ultrastructural alterations of the dental pellicle may partly explain the tooth-roughening effect caused by oral astringent stimuli. Astringents might modify the pellicle's protective properties against dental erosion, attrition, as well as bacterial adhesion, and by this means may influence tooth health. The findings may thus be particularly relevant for preventive dentistry. Copyright © 2017 Elsevier Ltd. All rights reserved.

Identification of Fragile Microscopic Structures during Mineral Transformations in Wet Supercritical CO2

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

Arey, Bruce W.; Kovarik, Libor; Qafoku, Odeta

2013-04-01

In this study we examine the nature of highly fragile reaction products that form in low water content super critical carbon dioxide (scCO2) using a combination of scanning electron microscopy/focus ion beam (SEM/FIB), confocal Raman spectroscopy, helium ion microscopy (HeIM), and transmission electron microscopy (TEM). HeIM images show these precipitates to be fragile rosettes that can readily decompose even under slight heating from an electron beam. Using the TEM revealed details on the interfacial structure between the newly formed surface precipitates and the underlying initial solid phases. The detailed microscopic analysis revealed that the growth of the precipitates either followedmore » a tip growth mechanism with precipitates forming directly on the forsterite surface if the initial solid was non-porous (natural forsterite) or growth from the surface of the precipitates where fluid was conducted through the porous (nanoforsterite) agglomerates to the growth center. The mechanism of formation of the hydrated/hydroxylated magnesium carbonate compound (HHMC) phases offers insight into the possible mechanisms of carbonate mineral formation from scCO2 solutions which has recently received a great deal of attention as the result of the potential for CO2 to act as an atmospheric greenhouse gas and impact overall global warming. The techniques used here to examine these fragile structures an also be used to examine a wide range of fragile material surfaces. SEM and FIB technologies have now been brought together in a single instrument, which represents a powerful combination for the studies in biological, geological and materials science.« less

People--things and data--ideas: bipolar dimensions?

PubMed

Tay, Louis; Su, Rong; Rounds, James

2011-07-01

We examined a longstanding assumption in vocational psychology that people-things and data-ideas are bipolar dimensions. Two minimal criteria for bipolarity were proposed and examined across 3 studies: (a) The correlation between opposite interest types should be negative; (b) after correcting for systematic responding, the correlation should be greater than -.40. In Study 1, a meta-analysis using 26 interest inventories with a sample size of 1,008,253 participants showed that meta-analytic correlations between opposite RIASEC (realistic, investigative, artistic, social, enterprising, conventional) types ranged from -.03 to .18 (corrected meta-analytic correlations ranged from -.23 to -.06). In Study 2, structural equation models (SEMs) were fit to the Interest Finder (IF; Wall, Wise, & Baker, 1996) and the Interest Profiler (IP; Rounds, Smith, Hubert, Lewis, & Rivkin, 1999) with sample sizes of 13,939 and 1,061, respectively. The correlations of opposite RIASEC types were positive, ranging from .17 to .53. No corrected correlation met the criterion of -.40 except for investigative-enterprising (r = -.67). Nevertheless, a direct estimate of the correlation between data-ideas end poles using targeted factor rotation did not reveal bipolarity. Furthermore, bipolar SEMs fit substantially worse than a multiple-factor representation of vocational interests. In Study 3, a two-way clustering solution on IF and IP respondents and items revealed a substantial number of individuals with interests in both people and things. We discuss key theoretical, methodological, and practical implications such as the structure of vocational interests, interpretation and scoring of interest measures for career counseling, and expert RIASEC ratings of occupations.

FIB-SEM tomography in biology.

PubMed

Kizilyaprak, Caroline; Bittermann, Anne Greet; Daraspe, Jean; Humbel, Bruno M

2014-01-01

Three-dimensional information is much easier to understand than a set of two-dimensional images. Therefore a layman is thrilled by the pseudo-3D image taken in a scanning electron microscope (SEM) while, when seeing a transmission electron micrograph, his imagination is challenged. First approaches to gain insight in the third dimension were to make serial microtome sections of a region of interest (ROI) and then building a model of the object. Serial microtome sectioning is a tedious and skill-demanding work and therefore seldom done. In the last two decades with the increase of computer power, sophisticated display options, and the development of new instruments, an SEM with a built-in microtome as well as a focused ion beam scanning electron microscope (FIB-SEM), serial sectioning, and 3D analysis has become far easier and faster.Due to the relief like topology of the microtome trimmed block face of resin-embedded tissue, the ROI can be searched in the secondary electron mode, and at the selected spot, the ROI is prepared with the ion beam for 3D analysis. For FIB-SEM tomography, a thin slice is removed with the ion beam and the newly exposed face is imaged with the electron beam, usually by recording the backscattered electrons. The process, also called "slice and view," is repeated until the desired volume is imaged.As FIB-SEM allows 3D imaging of biological fine structure at high resolution of only small volumes, it is crucial to perform slice and view at carefully selected spots. Finding the region of interest is therefore a prerequisite for meaningful imaging. Thin layer plastification of biofilms offers direct access to the original sample surface and allows the selection of an ROI for site-specific FIB-SEM tomography just by its pronounced topographic features.

Typologies of sexually explicit media use among MSM: An application of latent class analysis

PubMed Central

Erickson, Darin J.; Galos, Dylan L; Smolenski, Derek, J.; Iantaffi, Alex; Rosser, B.R. Simon

2014-01-01

The viewing of sexually explicit media (SEM) is widespread, especially among men, and research linking SEM viewing and sexual behavior has shown a variety of results, some positive (e.g., sexuality education) and some negative (e.g., poorer body image). These results might be due to limitations in measuring SEM consumption, particularly around typology. The goal of the current study was to examine potential patterns of SEM viewing activities. Using data from an online survey of men who have sex with men (MSM), we conducted latent class analyses of 15 SEM activities. Results suggested a three-class solution. The most prevalent class included over 60% of men and was characterized by viewing primarily safer-sex or conventional behaviors. The second class included 32% of men and had a similar albeit amplified pattern of viewing. The final class included just 7% of men and was marked by high levels of viewing of all activities, including fetish and kink. Compared to the conventional or safer-sex class, the other classes had lower internalized homonegativity, lower condom use self-efficacy, and higher SEM consumption or dose. Implications for HIV prevention, sexuality research and the SEM industry are discussed. PMID:25642301

Characterization of Pu-238 Heat Source Granule Containment

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

Richardson, Paul Dean II; Sanchez, Joey Leo; Wall, Angelique Dinorah

The Milliwatt Radioisotopic Themoelectric Generator (RTG) provides power for permissive-action links. Essentially these are nuclear batteries that convert thermal energy to electrical energy using a doped silicon-germanium thermopile. The thermal energy is provided by a heat source made of 238Pu, in the form of 238PuO 2 granules. The granules are contained by 3 layers of encapsulation. A thin T-111 liner surrounds the 238PuO 2 granules and protects the second layer (strength member) from exposure to the fuel granules. An outer layer of Hastalloy-C protects the T-111 from oxygen embrittlement. The T-111 strength member is considered the critical component in thismore » 238PuO 2 containment system. Any compromise in the strength member seen during destructive testing required by the RTG surveillance program is characterized. The T-111 strength member is characterized through Scanning Electron Microscopy (SEM), and Metallography. SEM is used in the Secondary Electron mode to reveal possible grain boundary deformation and/or cracking in the region of the strength member weld. Deformation and cracking uncovered by SEM are further characterized by Metallography. Metallography sections are mounted and polished, observed using optical microscopy, then documented in the form of microphotographs. SEM mat further be used to examine polished Metallography mounts to characterize elements using the SEM mode of Energy Dispersive X-ray spectroscopy (EDS).« less

A wavelet based method for automatic detection of slow eye movements: a pilot study.

PubMed

Magosso, Elisa; Provini, Federica; Montagna, Pasquale; Ursino, Mauro

2006-11-01

Electro-oculographic (EOG) activity during the wake-sleep transition is characterized by the appearance of slow eye movements (SEM). The present work describes an algorithm for the automatic localisation of SEM events from EOG recordings. The algorithm is based on a wavelet multiresolution analysis of the difference between right and left EOG tracings, and includes three main steps: (i) wavelet decomposition down to 10 detail levels (i.e., 10 scales), using Daubechies order 4 wavelet; (ii) computation of energy in 0.5s time steps at any level of decomposition; (iii) construction of a non-linear discriminant function expressing the relative energy of high-scale details to both high- and low-scale details. The main assumption is that the value of the discriminant function increases above a given threshold during SEM episodes due to energy redistribution toward higher scales. Ten EOG recordings from ten male patients with obstructive sleep apnea syndrome were used. All tracings included a period from pre-sleep wakefulness to stage 2 sleep. Two experts inspected the tracings separately to score SEMs. A reference set of SEM (gold standard) were obtained by joint examination by both experts. Parameters of the discriminant function were assigned on three tracings (design set) to minimize the disagreement between the system classification and classification by the two experts; the algorithm was then tested on the remaining seven tracings (test set). Results show that the agreement between the algorithm and the gold standard was 80.44+/-4.09%, the sensitivity of the algorithm was 67.2+/-7.37% and the selectivity 83.93+/-8.65%. However, most errors were not caused by an inability of the system to detect intervals with SEM activity against NON-SEM intervals, but were due to a different localisation of the beginning and end of some SEM episodes. The proposed method may be a valuable tool for computerized EOG analysis.

Measurement of pattern roughness and local size variation using CD-SEM: current status

NASA Astrophysics Data System (ADS)

Fukuda, Hiroshi; Kawasaki, Takahiro; Kawada, Hiroki; Sakai, Kei; Kato, Takashi; Yamaguchi, Satoru; Ikota, Masami; Momonoi, Yoshinori

2018-03-01

Measurement of line edge roughness (LER) is discussed from four aspects: edge detection, PSD prediction, sampling strategy, and noise mitigation, and general guidelines and practical solutions for LER measurement today are introduced. Advanced edge detection algorithms such as wave-matching method are shown effective for robustly detecting edges from low SNR images, while conventional algorithm with weak filtering is still effective in suppressing SEM noise and aliasing. Advanced PSD prediction method such as multi-taper method is effective in suppressing sampling noise within a line edge to analyze, while number of lines is still required for suppressing line to line variation. Two types of SEM noise mitigation methods, "apparent noise floor" subtraction method and LER-noise decomposition using regression analysis are verified to successfully mitigate SEM noise from PSD curves. These results are extended to LCDU measurement to clarify the impact of SEM noise and sampling noise on LCDU.