Growth of high-quality AlN epitaxial film by optimizing the Si substrate surface

NASA Astrophysics Data System (ADS)

Huang, Liegen; Li, Yuan; Wang, Wenliang; Li, Xiaochan; zheng, Yulin; Wang, Haiyan; Zhang, Zichen; Li, Guoqiang

2018-03-01

High-quality AlN epitaxial films have been grown on Si substrates by optimizing the hydrofluoric acid (HF) solution for cleaning of Si substrates. Effect of the Si substrate surface on the surface morphology and structural property of AlN epitaxial films is investigated in detail. It is revealed that as the concentration of HF solution increases from 0 to 2.0%, the surface morphology and the crystalline quality are initially improved and then get worse, and show an optimized value at 1.5%. The as-grown ∼200 nm-thick AlN epitaxial films on Si substrates grown with HF solution of 1.5% reveal the root-mean-square (RMS) surface roughness of 0.49 nm and the full-width at half-maximum for AlN(0002) X-ray rocking curve of 0.35°, indicating the smooth surface morphology and the high crystalline quality. The corresponding mechanism is proposed to interpret the effect of Si substrate surface on surface morphology and structural property of AlN epitaxial films, and provides an effective approach for the perspective fabrication of AlN-based devices.

Effect of the Cold-Sprayed Aluminum Coating-Substrate Interface Morphology on Bond Strength for Aircraft Repair Application

NASA Astrophysics Data System (ADS)

Blochet, Quentin; Delloro, Francesco; N'Guyen, Franck; Jeulin, Dominique; Borit, François; Jeandin, Michel

2017-04-01

This article is dealing with the effects of surface preparation of the substrate on aluminum cold-sprayed coating bond strength. Different sets of AA2024-T3 specimens have been coated with pure Al 1050 feedstock powder, using a conventional cold spray coating technique. The sets were grit-blasted (GB) before coating. The study focuses on substrate surface topography evolution before coating and coating-substrate interface morphology after coating. To study coating adhesion by LASAT® technique for each set, specimens with and without preceding GB treatment were tested in load-controlled conditions. Then, several techniques were used to evaluate the effects of substrate surface treatment on the final coating mechanical properties. Irregularities induced by the GB treatment modify significantly the interface morphology. Results showed that particle anchoring was improved dramatically by the presence of craters. The substrate surface was characterized by numerous anchors. Numerical simulation results exhibited the increasing deformation of particle onto the grit-blasted surface. In addition, results showed a strong relationship between the coating-substrate bond strength on the deposited material and surface preparation.

Experimental and theoretical study to explain the morphology of CaMoO4 crystals

NASA Astrophysics Data System (ADS)

Oliveira, F. K. F.; Oliveira, M. C.; Gracia, L.; Tranquilin, R. L.; Paskocimas, C. A.; Motta, F. V.; Longo, E.; Andrés, J.; Bomio, M. R. D.

2018-03-01

CaMoO4 crystals were prepared by a controlled co-precipitation method and processed in a domestic microwave-assisted hydrothermal system with two different surfactants (ethyl 4-dimethylaminobenzoate and 1,2,4,5-benzenetetracarboxylic dianhydride). The corresponding structures were characterized by X-ray diffraction and Rietveld refinement techniques, Fourier transform infrared spectroscopy, ultraviolet-visible absorption spectroscopy, and photoluminescence measurements. Field emission scanning electron microscopy was used to investigate the morphology of the as-synthesized aggregates. The structure, the surface stability of the (001), (112), (100), (110), (101), and (111) surfaces of CaMoO4, and their morphological transformations were investigated through systematic first-principles calculations within the density functional theory method at the B3LYP level. Analysis of the surface structures showed that the electronic properties were associated with the presence of undercoordinated [CaOx] (x = 5 and 6) and [MoOy] (y = 4 and 3) clusters. The relative surfaces energies were tuned to predict a complete map of the morphologies available through a Wulff construction approach. The results reveal that the experimental and theoretical morphologies obtained coincide when the surface energies of the (001) and (101) surfaces increase, while the surface energy of the (100) facet decreases simultaneously. The results provide a comprehensive catalog of the morphologies most likely to be present under realistic conditions, and will serve as a starting point for future studies on the surface chemistry of CaMoO4 crystals.

Surface morphology and structure of Ge layer on Si(111) after solid phase epitaxy

NASA Astrophysics Data System (ADS)

Yoshida, Ryoma; Tosaka, Aki; Shigeta, Yukichi

2018-05-01

The surface morphology change of a Ge layer on a Si(111) surface formed by solid phase epitaxy has been investigated with a scanning tunneling microscope (STM). The Ge film was deposited at room temperature and annealed at 400 °C or 600 °C. The STM images of the sample surface after annealing at 400 °C show a flat wetting layer (WL) with small three-dimensional islands on the WL. After annealing at 600 °C, the STM images show a surface roughening with large islands. From the relation between the average height of the roughness and the deposited layer thickness, it is confirmed that the diffusion of Ge atoms becomes very active at 600 °C. The Si crystal at the interface is reconstructed and the intermixing occurs over 600 °C. However, the intermixing is fairly restricted in the solid phase epitaxy growth at 400 °C. The surface morphology changes with the crystallization at 400 °C are discussed by the shape of the islands formed on the WL surface. It is shown that the diffusion of the Ge atoms in the amorphous phase is active even at 400 °C.

Strain relaxation induced surface morphology of heterogeneous GaInNAs layers grown on GaAs substrate

NASA Astrophysics Data System (ADS)

Gelczuk, Ł.; Jóźwiak, G.; Moczała, M.; Dłużewski, P.; Dąbrowska-Szata, M.; Gotszalk, T. P.

2017-07-01

The partially-relaxed heterogeneous GaInNAs layers grown on GaAs substrate by atmospheric pressure vapor phase epitaxy (AP-MOVPE) were investigated by transmission electron microscopy (TEM) and atomic force microscopy (AFM). The planar-view TEM image shows a regular 2D network of misfit dislocations oriented in two orthogonal 〈1 1 0〉 crystallographic directions at the (0 0 1) layer interface. Moreover, the cross-sectional view TEM image reveals InAs-rich and V-shaped precipitates in the near surface region of the GaInNAs epitaxial layer. The resultant undulating surface morphology, known as a cross-hatch pattern, is formed as observed by AFM. The numerical analysis of the AFM image of the GaInNAs layer surface with the well-defined cross-hatch morphology enabled us to determine a lower bound of actual density of misfit dislocations. However, a close correspondence between the asymmetric distribution of interfacial misfit dislocations and undulating surface morphology is observed.

Molecular-Scale Structural Controls on Nanoscale Growth Processes: Step-Specific Regulation of Biomineral Morphology

NASA Astrophysics Data System (ADS)

Dove, P. M.; Davis, K. J.; De Yoreo, J. J.; Orme, C. A.

2001-12-01

Deciphering the complex strategies by which organisms produce nanocrystalline materials with exquisite morphologies is central to understanding biomineralizing systems. One control on the morphology of biogenic nanoparticles is the specific interactions of their surfaces with the organic functional groups provided by the organism and the various inorganic species present in the ambient environment. It is now possible to directly probe the microscopic structural controls on crystal morphology by making quantitative measurements of the dynamic processes occurring at the mineral-water interface. These observations can provide crucial information concerning the actual mechanisms of growth that is otherwise unobtainable through macroscopic techniques. Here we use in situ molecular-scale observations of step dynamics and growth hillock morphology to directly resolve roles of principal impurities in regulating calcite surface morphologies. We show that the interactions of certain inorganic as well as organic impurities with the calcite surface are dependent upon the molecular-scale structures of step-edges. These interactions can assume a primary role in directing crystal morphology. In calcite growth experiments containing magnesium, we show that growth hillock structures become modified owing to the preferential inhibition of step motion along directions approximately parallel to the [010]. Compositional analyses have shown that Mg incorporates at different levels into the two types of nonequivalent steps, which meet at the hillock corner parallel to [010]. A simple calculation of the strain caused by this difference indicates that we should expect a significant retardation at this corner, in agreement with the observed development of [010] steps. If the low-energy step-risers produced by these [010] steps is perpendicular to the c-axis as seems likely from crystallographic considerations, this effect provides a plausible mechanism for the elongated calcite crystal habits found in natural environments that contain magnesium. In a separate study, step-specific interactions are also found between chiral aspartate molecules and the calcite surface. The L and D- aspartate enantiomers exhibit structure preferences for the different types of step-risers on the calcite surface. These site-specific interactions result in the transfer of asymmetry from the organic molecule to the crystal surface through the formation of chiral growth hillocks and surface morphologies. These studies yield direct experimental insight into the molecular-scale structural controls on nanocrystal morphology in biomineralizing systems.

Effects of nanoparticle shape on the morphology and properties of porous CdSe assemblies (aerogels).

PubMed

Yu, Hongtao; Brock, Stephanie L

2008-08-01

We demonstrate the effect of differently shaped CdSe nanoscale building blocks (dots, rods, branched nanoparticles, and hyperbranched nanoparticles) on the morphologies, surface characteristics, and optical properties of resultant porous CdSe nanostructured aerogels. Monolithic CdSe aerogels were produced by controlled oxidative removal of surface thiolate ligands from differently shaped CdSe nanoparticles to yield a wet gel, followed by CO(2) supercritical drying. The X-ray diffraction data show that the resultant CdSe aerogels maintain the crystalline phase of the building blocks without significant grain growth. However, the transmission electron microscopy images indicate that the morphology of CdSe aerogels changes from a colloid-type morphology to a polymer-type morphology when the building block changes from dot to rod or the branched nanoparticle. The morphology of the CdSe aerogel assembled from hyperbranched nanoparticles appears to be intermediate between the colloid-type and the polymer-type. Nitrogen physisorption measurements suggest that the surface areas and porosity are a direct function of the shape of the primary building blocks, with aerogels formed from rods or branched particles exhibiting the greatest surface areas (>200 m(2)/g) and those prepared from hyperbranched nanoparticles exhibiting the least (<100 m(2)/g). Band gap measurements and photoluminescence studies show that the as-prepared CdSe aerogels retain to a large extent the intrinsic quantum confinement of the differently shaped building blocks, despite being connected into a 3D network.

Buckling Instabilities in Polymer Brush Surfaces via Postpolymerization Modification

DOE PAGES

Guo, Wei; Reese, Cassandra M.; Xiong, Li; ...

2017-10-30

We report a simple route to engineer ultrathin polymer brush surfaces with wrinkled morphologies using postpolymerization modification (PPM), where the length scale of the buckled features can be tuned using PPM reaction time. Here, we show that partial crosslinking of the outer layer of the polymer brush under poor solvent conditions is critical to obtain wrinkled morphologies upon swelling.

Bio-inspired scale-like surface textures and their tribological properties.

PubMed

Greiner, Christian; Schäfer, Michael

2015-06-30

Friction, wear and the associated energy dissipation are major challenges in all systems containing moving parts. Examples range from nanoelectromechanical systems over hip prosthesis to off-shore wind turbines. Bionic approaches have proven to be very successful in many engineering problems, while investigating the potential of a bio-inspired approach in creating morphological surface textures is a relatively new field of research. Here, we developed laser-created textures inspired by the scales found on the skin of snakes and certain lizards. We show that this bio-inspired surface morphology reduced dry sliding friction forces by more than 40%. In lubricated contacts the same morphology increased friction by a factor of three. Two different kinds of morphologies, one with completely overlapping scales and one with the scales arranged in individual rows, were chosen. In lubricated as well as unlubricated contacts, the surface texture with the scales in rows showed lower friction forces than the completely overlapping ones. We anticipate that these results could have significant impact in all dry sliding contacts, ranging from nanoelectromechanical and micro-positioning systems up to large-scale tribological contacts which cannot be lubricated, e.g. because they are employed in a vacuum environment.

Influence of Chemical Precleaning on the Plasma Treatment Efficiency of Aluminum by RF Plasma Pencil

NASA Astrophysics Data System (ADS)

Vadym, Prysiazhnyi; Pavel, Slavicek; Eliska, Mikmekova; Milos, Klima

2016-04-01

This paper is aimed to show the influence of initial chemical pretreatment prior to subsequent plasma activation of aluminum surfaces. The results of our study showed that the state of the topmost surface layer (i.e. the surface morphology and chemical groups) of plasma modified aluminum significantly depends on the chemical precleaning. Commonly used chemicals (isopropanol, trichlorethane, solution of NaOH in deionized water) were used as precleaning agents. The plasma treatments were done using a radio frequency driven atmospheric pressure plasma pencil developed at Masaryk University, which operates in Ar, Ar/O2 gas mixtures. The effectiveness of the plasma treatment was estimated by the wettability measurements, showing high wettability improvement already after 0.3 s treatment. The effects of surface cleaning (hydrocarbon removal), surface oxidation and activation (generation of OH groups) were estimated using infrared spectroscopy. The changes in the surface morphology were measured using scanning electron microscopy. Optical emission spectroscopy measurements in the near-to-surface region with temperature calculations showed that plasma itself depends on the sample precleaning procedure.

Effects of aqueous ammonia treatment on fiber's surface morphology and enzymatic digestibility of empty fruit bunch fiber (EFBF)

NASA Astrophysics Data System (ADS)

Ling, Tang Pei; Hassan, Osman

2013-11-01

This study was conducted to investigate the effects of aqueous ammonia reflux and soaked treatment on the fiber's surface morphology and enzymatic digestibility of empty fruit bunch fiber (EFBF). The surface morphological changes of the fiber after aqueous ammonia treatment was linked to the sugars yield by enzymatic hydrolysis. The effectiveness of 6.25% aqueous ammonia treatment in improving enzymatic digestibility of EFBF was initially studied in reflux system and by soaking. The results showed that soaked treatment was more effective than reflux system. Further study on soaked treatment of EFBF was carried out by increasing the ammonia concentration to 12.50%. Soaking in aqueous ammonia was conducted at 30°C and 50°C for 24 hours. The results of enzymatic hydrolysis showed that sugar yield from EFBF soaked in 12.50% aqueous ammonia at 50°C was the highest. Approximately 242.91±15.50 mg/g EFBF of xylose and 320.49±28.31 mg/g EFBF of glucose were produced by the action of enzyme Cellic Ctec 2. Results of scanning electron microscopic showed that aqueous ammonia treatment by soaking had caused a more severe structural distortion on the fiber's surface and higher removal of silica bodies that embedded on the fiber than those in reflux system. The changes on the fiber's surface morphology were believed is the contributing factor that improved the enzymatic digestibility of EFBF after aqueous ammonia treatment.

Complexation of lysozyme with adsorbed PtBS-b-SCPI block polyelectrolyte micelles on silver surface.

PubMed

Papagiannopoulos, Aristeidis; Christoulaki, Anastasia; Spiliopoulos, Nikolaos; Vradis, Alexandros; Toprakcioglu, Chris; Pispas, Stergios

2015-01-20

We present a study of the interaction of the positively charged model protein lysozyme with the negatively charged amphiphilic diblock polyelectrolyte micelles of poly(tert-butylstyrene-b-sodium (sulfamate/carboxylate)isoprene) (PtBS-b-SCPI) on the silver/water interface. The adsorption kinetics are monitored by surface plasmon resonance, and the surface morphology is probed by atomic force microscopy. The micellar adsorption is described by stretched-exponential kinetics, and the micellar layer morphology shows that the micelles do not lose their integrity upon adsorption. The complexation of lysozyme with the adsorbed micellar layers depends on the micelles arrangement and density in the underlying layer, and lysozyme follows the local morphology of the underlying roughness. When the micellar adsorbed amount is small, the layers show low capacity in protein complexation and low resistance in loading. When the micellar adsorbed amount is high, the situation is reversed. The adsorbed layers both with or without added protein are found to be irreversibly adsorbed on the Ag surface.

Effect of mass density on surface morphology of electrodeposited manganese oxide films

NASA Astrophysics Data System (ADS)

Singh, Avtar; Kumar, Davinder; Thakur, Anup; Kaur, Raminder

2018-05-01

This work focus on high surface area morphology of manganese oxide films which are currently required for electrochemical capacitor electrode to enhance their performance. Electrodeposition of manganese oxide films was carried out using Chronoamperometry for different deposition time ranging from 30 to 120 sec. Cronoamperomertic I-T integrated data have been used to analyze active mass of all electrodeposited films. Morphological study of the deposited films with different mass was carried out through scanning electron microscopy. Film deposited for 30 sec time show highest porous morphology than others. Manganese oxide films with high porosity are suitable for electrochemical capacitor electrode.

The Role of Surface Chemistry in Adhesion and Wetting of Gecko Toe Pads

PubMed Central

Badge, Ila; Stark, Alyssa Y.; Paoloni, Eva L.; Niewiarowski, Peter H.; Dhinojwala, Ali

2014-01-01

An array of micron-sized setal hairs offers geckos a unique ability to walk on vertical surfaces using van der Waals interactions. Although many studies have focused on the role of surface morphology of the hairs, very little is known about the role of surface chemistry on wetting and adhesion. We expect that both surface chemistry and morphology are important, not only to achieve optimum dry adhesion but also for increased efficiency in self-cleaning of water and adhesion under wet conditions. Here, we used a plasma-based vapor deposition process to coat the hairy patterns on gecko toe pad sheds with polar and non-polar coatings without significantly perturbing the setal morphology. By a comparison of wetting across treatments, we show that the intrinsic surface of gecko setae has a water contact angle between 70–90°. As expected, under wet conditions, adhesion on a hydrophilic surface (glass) was lower than that on a hydrophobic surface (alkyl-silane monolayer on glass). Surprisingly under wet and dry conditions the adhesion was comparable on the hydrophobic surface, independent of the surface chemistry of the setal hairs. This work highlights the need to utilize morphology and surface chemistry in developing successful synthetic adhesives with desirable adhesion and self-cleaning properties. PMID:25323067

The Role of Surface Chemistry in Adhesion and Wetting of Gecko Toe Pads

NASA Astrophysics Data System (ADS)

Badge, Ila; Stark, Alyssa Y.; Paoloni, Eva L.; Niewiarowski, Peter H.; Dhinojwala, Ali

2014-10-01

An array of micron-sized setal hairs offers geckos a unique ability to walk on vertical surfaces using van der Waals interactions. Although many studies have focused on the role of surface morphology of the hairs, very little is known about the role of surface chemistry on wetting and adhesion. We expect that both surface chemistry and morphology are important, not only to achieve optimum dry adhesion but also for increased efficiency in self-cleaning of water and adhesion under wet conditions. Here, we used a plasma-based vapor deposition process to coat the hairy patterns on gecko toe pad sheds with polar and non-polar coatings without significantly perturbing the setal morphology. By a comparison of wetting across treatments, we show that the intrinsic surface of gecko setae has a water contact angle between 70-90°. As expected, under wet conditions, adhesion on a hydrophilic surface (glass) was lower than that on a hydrophobic surface (alkyl-silane monolayer on glass). Surprisingly under wet and dry conditions the adhesion was comparable on the hydrophobic surface, independent of the surface chemistry of the setal hairs. This work highlights the need to utilize morphology and surface chemistry in developing successful synthetic adhesives with desirable adhesion and self-cleaning properties.

Morphology-Driven Control of Metabolite Selectivity Using Nanostructure-Initiator Mass Spectrometry

DOE PAGES

Gao, Jian; Louie, Katherine B.; Steinke, Philipp; ...

2017-05-26

Nanostructure-initiator mass spectrometry (NIMS) is a laser desorption/ionization analysis technique based on the vaporization of a nanostructure-trapped liquid "initiator" phase. Here we report an intriguing relationship between NIMS surface morphology and analyte selectivity. Scanning electron microscopy and spectroscopic ellipsometry were used to characterize the surface morphologies of a series of NIMS substrates generated by anodic electrochemical etching. Mass spectrometry imaging was applied to compare NIMS sensitivity of these various surfaces toward the analysis of diverse analytes. The porosity of NIMS surfaces was found to increase linearly with etching time where the pore size ranged from 4 to 12 nm withmore » corresponding porosities estimated to be 7-70%. Surface morphology was found to significantly and selectively alter NIMS sensitivity. The small molecule ( < 2k Da) sensitivity was found to increase with increased porosity, whereas low porosity had the highest sensitivity for the largest molecules examined. Estimation of molecular sizes showed that this transition occurs when the pore size is < 3× the maximum of molecular dimensions. While the origins of selectivity are unclear, increased signal from small molecules with increased surface area is consistent with a surface area restructuring-driven desorption/ionization process where signal intensity increases with porosity. In contrast, large molecules show highest signal for the low-porosity and small-pore-size surfaces. We attribute this to strong interactions between the initiator-coated pore structures and large molecules that hinder desorption/ionization by trapping large molecules. This finding may enable us to design NIMS surfaces with increased specificity to molecules of interest.« less

Effects of different substrates on the sprint performance of lizards.

PubMed

Tulli, Maria Jose; Abdala, Virginia; Cruz, Felix B

2012-03-01

The variation in substrate structure is one of the most important determinants of the locomotor abilities of lizards. Lizards are found across a range of habitats, from large rocks to loose sand, each of them with conflicting mechanical demands on locomotion. We examined the relationships among sprint speed, morphology and different types of substrate surfaces in species of lizards that exploit different structural habitats (arboreal, saxicolous, terrestrial and arenicolous) in a phylogenetic context. Our main goals were to assess which processes drive variability in morphology (i.e. phylogeny or adaptation to habitat) in order to understand how substrate structure affects sprint speed in species occupying different habitats and to determine the relationship between morphology and performance. Liolaemini lizards show that most morphological traits are constrained by phylogeny, particularly toe 3, the femur and foot. All ecological groups showed significant differences on rocky surfaces. Surprisingly, no ecological group performed better on the surface resembling its own habitat. Moreover, all groups exhibited significant differences in sprint speed among the three different types of experimental substrates and showed the best performance on sand, with the exception of the arboreal group. Despite the fact that species use different types of habitats, the highly conservative morphology of Liolaemini species and the similar levels of performance on different types of substrates suggest that they confer to the 'jack of all trades and master of none' principle.

Structural and morphological modifications of polymer thin film in the presence of nonsolvent

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

Talukdar, Hrishikesh, E-mail: hiasst@yahoo.in; Kundu, Sarathi

Thin films of sodium poly(acrylic acid) salt (Na-PAA) have been investigated to obtain the modification of the out-of-plane structure and surface morphology in the presence of toluene which is considered as nonsolvent for Na-PAA. X-ray reflectivity analysis show that the out-of-plane thickness of the Na-PAA film increases if the film is kept for longer time inside the toluene. For the thicker film the effect of toluene is more pronounced than the thinner one. Surface morphology obtained from the atomic force microscopy shows that the top surface becomes relatively rough after the dipping of the Na-PAA film inside toluene. Although toluenemore » is nonsolvent for Na-PAA molecules, however, the effect of restructuring of the nanometer-thick polymer film cannot be ignored. The reason for such structural modification has been proposed.« less

Morphological characterization of the anuran integument of the Proceratophrys and Odontophrynus genera (Amphibia, Anuran, Leptodactylidae).

PubMed

Felsemburgh, F A; Carvalho-e-Silva, S P; de Brito-Gitirana, L

2007-01-01

The morphological characteristics of the leptodactylid integument of Proceratophrys and Odontophrynus genera were investigated by means of stereoscopic, low vacuum scanning electron and light microscopy. The integument surface of Proceratophrys boiei, Proceratophrys laticeps and Proceratophrys appendiculata exhibited several projections, while the integument of Odontophrynus americanus had rounded elevations with smooth profile. Light microscopic observations showed the basic integument morphology for all anurans, i.e., an epidermis and a dermis, which is subdivided into a spongious layer and a compact layer. The epidermis is formed by basal, intermediary and cornified layers. However, in Proceratophrys genus the cornified layer had an irregular outline, while in O. americanus the external surface was smooth. In the spongious dermis, mucous and venom exocrine glands were observed, but in O. americanus an exclusive glandular type with apocrine secretory pattern was identified. The integument morphology showed peculiar characteristics that may be helpful for genus distinction. Thus, morphological methods may be considered as an efficient means to characterize and to differentiate anuran genera.

Origin of phase shift in atomic force microscopic investigation of the surface morphology of NR/NBR blend film.

PubMed

Thanawan, S; Radabutra, S; Thamasirianunt, P; Amornsakchai, T; Suchiva, K

2009-01-01

Atomic force microscopy (AFM) was used to study the morphology and surface properties of NR/NBR blend. Blends at 1/3, 1/1 and 3/1 weight ratios were prepared in benzene and formed film by casting. AFM phase images of these blends in tapping mode displayed islands in the sea morphology or matrix-dispersed structures. For blend 1/3, NR formed dispersed phase while in blends 1/1 and 3/1 phase inversion was observed. NR showed higher phase shift angle in AFM phase imaging for all blends. This circumstance was governed by adhesion energy hysteresis between the device tip and the rubber surface rather than surface stiffness of the materials, as proved by force distance measurements in the AFM contact mode.

Changes in surface morphology and mineralization level of human enamel following in-office bleaching with 35% hydrogen peroxide and light irradiation.

PubMed

Berger, Sandrine Bittencourt; Cavalli, Vanessa; Ambrosano, Glaucia Maria Bovi; Giannini, Marcelo

2010-01-01

The objective of this study was to evaluate the alterations on surface morphology and mineral loss of human enamel following in-office bleaching with 35% hydrogen peroxide and light irradiation. Dental enamel samples were obtained from human third molars and randomly divided into 10 groups (n = 10). The control group remained untreated. Bleached groups were treated with one of three whitening products. Bleaching was performed in a single session, during which bleaching gel was applied to the enamel surface three times for 10 minutes each time. During treatment, the bleaching agents were either irradiated by a halogen light or an LED/diode laser or were not irradiated at all. Microhardness testing was performed with a Knoop indentor and the surface morphologic observations were carried out by scanning electron microscopy (SEM). Cross-sectional microhardness (CSMH) and polarized light microscopy (PLM) were used to measure the depth of demineralization. The results revealed a significant decrease in surface microhardness values and changes to the enamel morphology after bleaching. CSMH and PLM showed that bleached enamel presented lower volume percentage of mineral up to 40 micrometers from the enamel surface and demineralization areas located in the subsuperficial region of enamel, respectively. It was concluded that 35% hydrogen peroxide can alter the surface morphology and the mineralization level of the dental enamel surface and sub-surface regardless of what type of bleaching light is used.

Pinus Monophylla (Single Needled Pinyon Pine) show morphological changes in needle cell size and stomata over the past 100 years of rising CO2 in Western Arid Ecosystems.

NASA Astrophysics Data System (ADS)

Van De Water, P. K.

2016-12-01

The size, frequency, and morphology of leaf surface stomata is used to reconstruct past levels of atmospheric carbon dioxide over geologic time. This technique relies on measuring cell and cell-clusters to correlate with changes of known carbon dioxide levels in the atmosphere. Unfortunately, not all plants are suitable because the occurrence and placement of stomatal cell-complexes differ significantly between plant families. Monocot and dicot angiosperms exhibit different types of stomata and stomatal complexes that lack order and thus are unsuitable. But, in gymnosperms, the number and distribution of stomata and pavement cells is formalized and can be used to reconstruct past atmospheric carbon dioxide levels. However, characteristic of each plant species must still be considered. For example, conifers are useful but are divided into two-needle to five-needle pines, or have irregular surface morphology (Pseudotsuga sp. and Tsuga sp. needles). This study uses Pinus monophylla an undivided needle morphology, that being a cylinder has no interior surface cells. Pinus monophylla (single needle pinyon) needles were collected along Geiger Grade (Nevada State Highway 341, Reno) in 2005 and 2013 from 1500m to 2195m. Herbarium samples were also collected from 13 historic collections made between 1911 and 1994. The study determined changes with elevation and/or over time using in these populations. Using Pinus monophylla, insured needles represented a single surface with stomata, stomatal complex cells, and co-occurring pavement cell types. Results show decreased stomatal densities (stomata/area), stomatal index (stomata/stomata + epidermal cells) and stable stomata per row (stomata/row) . Epidermal cell density (Epidermal Cells /Area), and Pavement cell density (Pavement cell/area) track stomatal density similarly. Data comparison, using elevation in the 2005 and 2013 collections showed no-significant trends. Individual stomatal complexes show no differences in the size and shape over time or with elevation. Stomata morphology and the stomatal pores appear conservative. However some complex cells show a morphology suggesting they are not fully formed and functional. These characteristics appear often in the modern material suggesting some stomata never fully develop.

Characterization of retrieved orthodontic miniscrew implants.

PubMed

Eliades, Theodore; Zinelis, Spiros; Papadopoulos, Moschos A; Eliades, George

2009-01-01

The purposes of this study were to characterize the morphologic, structural, and compositional alterations and to assess any hardness changes in used orthodontic miniscrew implants. Eleven miniscrew implants (Aarhus Anchorage System, Medicon eG, Tuttlingen, Germany) placed in 5 patients were retrieved after successful service of 3.5 to 17.5 months; none showed signs of mobility or failure. These implants, and brand-, type-, and size-matched specimens as controls, were subjected to multi-technique characterization. Optical microscopy indicated loss of gloss with variable discoloration. Scanning electron microscopy and x-ray microanalysis showed morphologic alteration of the miniscrew implant surfaces with integuments formed on the surface. The materials precipitated on the surfaces were sodium, potassium, chlorine, iron, calcium, and phosphorus from the contact of the implant with biologic fluids such as blood and exudates, forming sodium chloride, potassium chloride, and calcium-phosphorus precipitates. The composition of the implant was similar to that of a titanium alloy. X-ray microtomography analysis showed no bulk structure alterations. Vickers microhardness testing showed no increased bulk or surface hardness of the retrieved specimens compared with the controls, excluding the possibility of strain-hardening phenomena as a result of self-tapping and self-drilling placement and related loading conditions. Used titanium-alloy miniscrew implants have morphologic and surface structural alterations including adsorption of an integument that is calcified as a result of contact of the implants with biologic fluids. Randomly organized osseointegration islets on these smooth titanium-alloy miniscrew surfaces might be enhanced by the extended period of retention in alveolar bone in spite of the smooth surface and immediate loading pattern of these implants.

Nano-scale surface morphology, wettability and osteoblast adhesion on nitrogen plasma-implanted NiTi shape memory alloy.

PubMed

Liu, X M; Wu, S L; Chu, Paul K; Chung, C Y; Chu, C L; Chan, Y L; Lam, K O; Yeung, K W K; Lu, W W; Cheung, K M C; Luk, K D K

2009-06-01

Plasma immersion ion implantation (PIII) is an effective method to increase the corrosion resistance and inhibit nickel release from orthopedic NiTi shape memory alloy. Nitrogen was plasma-implanted into NiTi using different pulsing frequencies to investigate the effects on the nano-scale surface morphology, structure, wettability, as well as biocompatibility. X-ray photoelectron spectroscopy (XPS) results show that the implantation depth of nitrogen increases with higher pulsing frequencies. Atomic force microscopy (AFM) discloses that the nano-scale surface roughness increases and surface features are changed from islands to spiky cones with higher pulsing frequencies. This variation in the nano surface structures leads to different surface free energy (SFE) monitored by contact angle measurements. The adhesion, spreading, and proliferation of osteoblasts on the implanted NiTi surface are assessed by cell culture tests. Our results indicate that the nano-scale surface morphology that is altered by the implantation frequencies impacts the surface free energy and wettability of the NiTi surfaces, and in turn affects the osteoblast adhesion behavior.

Effects of aqueous ammonia treatment on fiber’s surface morphology and enzymatic digestibility of empty fruit bunch fiber (EFBF)

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

Ling, Tang Pei; Hassan, Osman

This study was conducted to investigate the effects of aqueous ammonia reflux and soaked treatment on the fiber’s surface morphology and enzymatic digestibility of empty fruit bunch fiber (EFBF). The surface morphological changes of the fiber after aqueous ammonia treatment was linked to the sugars yield by enzymatic hydrolysis. The effectiveness of 6.25% aqueous ammonia treatment in improving enzymatic digestibility of EFBF was initially studied in reflux system and by soaking. The results showed that soaked treatment was more effective than reflux system. Further study on soaked treatment of EFBF was carried out by increasing the ammonia concentration to 12.50%.more » Soaking in aqueous ammonia was conducted at 30°C and 50°C for 24 hours. The results of enzymatic hydrolysis showed that sugar yield from EFBF soaked in 12.50% aqueous ammonia at 50°C was the highest. Approximately 242.91±15.50 mg/g EFBF of xylose and 320.49±28.31 mg/g EFBF of glucose were produced by the action of enzyme Cellic Ctec 2. Results of scanning electron microscopic showed that aqueous ammonia treatment by soaking had caused a more severe structural distortion on the fiber’s surface and higher removal of silica bodies that embedded on the fiber than those in reflux system. The changes on the fiber’s surface morphology were believed is the contributing factor that improved the enzymatic digestibility of EFBF after aqueous ammonia treatment.« less

Surface Morphology of Vapor-Deposited Chitosan: Evidence of Solid-State Dewetting during the Formation of Biopolymer Films.

PubMed

Retamal, Maria Jose; Corrales, Tomas P; Cisternas, Marcelo A; Moraga, Nicolas H; Diaz, Diego I; Catalan, Rodrigo E; Seifert, Birger; Huber, Patrick; Volkmann, Ulrich G

2016-03-14

Chitosan is a useful and versatile biopolymer with several industrial and biological applications. Whereas its physical and physicochemical bulk properties have been explored quite intensively in the past, there is a lack of studies regarding the morphology and growth mechanisms of thin films of this biopolymer. Of particular interest for applications in bionanotechnology are ultrathin films with thicknesses under 500 Å. Here, we present a study of thin chitosan films prepared in a dry process using physical vapor deposition and in situ ellipsometric monitoring. The prepared films were analyzed with atomic force microscopy in order to correlate surface morphology with evaporation parameters. We find that the surface morphology of our final thin films depends on both the optical thickness, i.e., measured with ellipsometry, and the deposition rate. Our work shows that ultrathin biopolymer films can undergo dewetting during film formation, even in the absence of solvents and thermal annealing.

Theoretical approach for determining the relation between the morphology and surface magnetism of Co3O4

NASA Astrophysics Data System (ADS)

Ribeiro, R. A. P.; de Lazaro, S. R.; Gracia, L.; Longo, E.; Andrés, J.

2018-05-01

Precisely controlling the different aspects of the morphology and magnetic properties of metal oxides are fundamental to materials design. A theoretical approach, based on the Wulff construction and magnetization density (M) index, is presented to clarify the relation between the morphology and surface magnetism. The M index allows us to evaluate the uncompensated spins at the (1 0 0), (1 1 0), (1 1 1) and (1 1 2) surfaces of Co3O4 with a spinel structure. The investigated morphologies show an excellent agreement with the experimental results, with the main contribution coming from the (1 0 0) and (1 1 1) magnetic planes. The present results are also helpful in clarifying the intriguing magnetic properties reported for Co3O4 nanoparticles, suggesting that the same technique may serve as a guide for the study of shape-oriented magnetic materials.

Secondary instabilities modulate cortical complexity in the mammalian brain

NASA Astrophysics Data System (ADS)

Budday, Silvia; Steinmann, Paul; Kuhl, Ellen

2015-10-01

Disclosing the origin of convolutions in the mammalian brain remains a scientific challenge. Primary folds form before we are born: they are static, well defined and highly preserved across individuals. Secondary folds occur and disappear throughout our entire lifetime: they are dynamic, irregular and highly variable among individuals. While extensive research has improved our understanding of primary folding in the mammalian brain, secondary folding remains understudied and poorly understood. Here, we show that secondary instabilities can explain the increasing complexity of our brain surface as we age. Using the nonlinear field theories of mechanics supplemented by the theory of finite growth, we explore the critical conditions for secondary instabilities. We show that with continuing growth, our brain surface continues to bifurcate into increasingly complex morphologies. Our results suggest that even small geometric variations can have a significant impact on surface morphogenesis. Secondary bifurcations, and with them morphological changes during childhood and adolescence, are closely associated with the formation and loss of neuronal connections. Understanding the correlation between neuronal connectivity, cortical thickness, surface morphology and ultimately behaviour, could have important implications on the diagnostics, classification and treatment of neurological disorders.

Biogeography, phylogeny, and morphological evolution of central Texas cave and spring salamanders

PubMed Central

2013-01-01

Background Subterranean faunal radiations can result in complex patterns of morphological divergence involving both convergent or parallel phenotypic evolution and cryptic species diversity. Salamanders of the genus Eurycea in central Texas provide a particularly challenging example with respect to phylogeny reconstruction, biogeography and taxonomy. These predominantly aquatic species inhabit karst limestone aquifers and spring outflows, and exhibit a wide range of morphological and genetic variation. We extensively sampled spring and cave populations of six Eurycea species within this group (eastern Blepsimolge clade), to reconstruct their phylogenetic and biogeographic history using mtDNA and examine patterns and origins of cave- and surface-associated morphological variation. Results Genetic divergence is generally low, and many populations share ancestral haplotypes and/or show evidence of introgression. This pattern likely indicates a recent radiation coupled with a complex history of intermittent connections within the aquatic karst system. Cave populations that exhibit the most extreme troglobitic morphologies show no or very low divergence from surface populations and are geographically interspersed among them, suggesting multiple instances of rapid, parallel phenotypic evolution. Morphological variation is diffuse among cave populations; this is in contrast to surface populations, which form a tight cluster in morphospace. Unexpectedly, our analyses reveal two distinct and previously unrecognized morphological groups encompassing multiple species that are not correlated with spring or cave habitat, phylogeny or geography, and may be due to developmental plasticity. Conclusions The evolutionary history of this group of spring- and cave-dwelling salamanders reflects patterns of intermittent isolation and gene flow influenced by complex hydrogeologic dynamics that are characteristic of karst regions. Shallow genetic divergences among several species, evidence of genetic exchange, and nested relationships across morphologically disparate cave and spring forms suggests that cave invasion was recent and many troglobitic morphologies arose independently. These patterns are consistent with an adaptive-shift hypothesis of divergence, which has been proposed to explain diversification in other karst fauna. While cave and surface forms often do not appear to be genetically isolated, morphological diversity within and among populations may be maintained by developmental plasticity, selection, or a combination thereof. PMID:24044519

Prolymphocytic leukaemia: surface morphology in 21 cases as seen by scanning electron microscopy and comparison with B-type CLL and CLL in 'prolymphocytoid' transformation.

PubMed

Polliack, A; Leizerowitz, R; Berrebi, A; Gamliel, H; Galili, N; Gurfel, D; Catovsky, D

1984-08-01

The surface architecture of leukaemic cells obtained from 21 cases of proven prolymphocytic leukaemia (PLL) and eight cases of chronic lymphocytic leukaemia (CLL) with 'prolymphocytoid' transformation (PL-CLL) was compared with the cell surface morphology of leukaemic cells obtained from 46 cases of B-type CLL, using the scanning electron microscope (SEM). All cases were defined by cytochemistry, immunological markers and transmission electron microscopy prior to SEM examination. B-CLL cells showed the well-recognized spectrum of surface architecture described in earlier studies. The majority of cells had moderate numbers of short microvilli, although in a minority, cells with relatively smooth surfaces predominated. In seven of the eight cases of PL-CLL, cells were villous in nature and in this respect similar to CLL cells; however, more cells with dense microvilli were seen. The prolymphocytic cells were recognized by their larger size and in 18 of the 19 cases of B-derived PLL, villous cells predominated. Two cases of T-derived PLL showed variable cell surface morphology ranging from smooth to moderately villous. It appears that B-PLL cells are most frequently villous and display more surface microvilli than B-CLL cells. B-prolymphocytes display the surface features regarded as characteristic for neoplastic B-cells as seen in patients with B-type lymphoma and leukaemia.

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

Yan, Wei; Liu, Hongtao, E-mail: liuht100@126.com; Sun, Qinghe

A facile and quick fabrication method was proposed to prepare superhydrophobic surfaces on iron substrate by chemical immersion and subsequent stearic acid modification. The association between wettability and surface morphology was studied through altering the copper ion concentration and immersion time. Surface tension instrument, scanning electron microscopy, x-ray diffraction, x-ray photoelectron spectroscopy, and electrochemical workstation were used to characterize the wettability, physical morphology, chemical composition, and corrosion resistance ability of the prepared film. Results showed that both the rough micro/nanostructures and low surface energy material play critical roles in surface wettability. The superhydrophobic film achieved a better anticorrosion property comparedmore » to barrier iron by analysis of open circuit potential, potentiodynamic polarization curves, and Nyquist plots. In addition, the superhydrophobic surface showed excellent performance of acid and alkali resistance, anti-icing, and self-cleaning through a series of environmental tests. This study provides a valid method for quick-preparation of the stable superhydrophobic surfaces, which has a promising application in steel buildings and facilities.« less

Influence of surface phenomena in oxidative desulfurization with WOx/ZrO2 catalysts

NASA Astrophysics Data System (ADS)

Torres-García, E.; Canizal, G.; Velumani, S.; Ramírez-Verduzco, L. F.; Murrieta-Guevara, F.; Ascencio, J. A.

2004-12-01

Oil refinery related catalysis, particularly hydro desulfurization is viewed as a mature technology, but still we view that more efforts have to be made to boost the efficiency of the existing catalysts. So in this article we report the use of WOx/ZrO2 catalysts for the oxidation of dibenzothiophene (DBT) as a more effective material in nanometer scales. The WOx/ZrO2 samples were prepared by solid impregnation of ZrO2-x(OH)2x with ammonium metatungstate solution maintaining the pH at 10. Detailed structural and surface morphological analyses were carried out using Raman spectroscopy and Atomic force microscopy. In order to understand the catalytic activity which is largely influenced by the surface morphology, an interpretation based on the experimental results is given. The results showed an important correlation between the catalytic efficiency with the morphology of the surface which is identified as arrays of planes with steps of around 10 nm with the structures showing faceting with a preferential angle of 90°. It was established that when the number of W atoms in the surface increase the catalytic efficiency also increases. Thus we conclude that the material efficiency as a catalyst is directly related with the surface structure.

Evaluation of Fine Aggregate Morphology by Image Method and Its Effect on Skid-Resistance of Micro-Surfacing.

PubMed

Xiao, Yue; Wang, Feng; Cui, Peide; Lei, Lei; Lin, Juntao; Yi, Mingwei

2018-05-29

Micro-surfacing is a widely used pavement preventive maintenance technology used all over the world, due to its advantages of fast construction, low maintenance cost, good waterproofness, and skid-resistance performance. This study evaluated the fine aggregate morphology and surface texture of micro-surfacing by AIMS (aggregate image measurement system), and explored the effect of aggregate morphology on skid-resistance of single-grade micro-surfacing. Sand patch test and British pendulum test were also used to detect skid-resistance for comparison with the image-based method. Wet abrasion test was used to measure skid-resistance durability for feasibility verification of single-grade micro-surfacing. The results show that the effect of Form2D on the skid-resistance of micro-surfacing is much stronger than that of angularity. Combining the feasibility analysis of durability and skid-resistance, 1.18⁻2.36 grade micro-surfacing meets the requirements of durability and skid-resistance at the same time. This study also determined that, compared with British pendulum test, the texture result obtained by sand patch test fits better with results of image method.

Nanoscale Morphology Evolution Under Ion Irradiation

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

Aziz, Michael J.

We showed that the half-century-old paradigm of morphological instability under irradiation due to the curvature-dependence of the sputter yield, can account neither for the phase diagram nor the amplification or decay rates that we measure in the simplest possible experimental system -- an elemental semiconductor with an amorphous surface under noble-gas ion irradiation; We showed that a model of pattern formation based on the impact-induced redistribution of atoms that do not get sputtered away explains our experimental observations; We developed a first-principles, parameter-free approach for predicting morphology evolution, starting with molecular dynamics simulations of single ion impacts, lasting picoseconds, andmore » upscaling through a rigorous crater-function formalism to develop a partial differential equation that predicts morphology evolution on time scales more than twelve orders of magnitude longer than can be covered by the molecular dynamics; We performed the first quantitative comparison of the contributions to morphological instability from sputter removal and from impact-induced redistribution of atoms that are removed, and showed that the former is negligible compared to the latter; We established a new paradigm for impact-induced morphology evolution based on crater functions that incorporate both redistribution and sputter effects; and We developed a model of nanopore closure by irradiation-induced stress and irradiationenhanced fluidity, for the near-surface irradiation regime in which nuclear stopping predominates, and showed that it explains many aspects of pore closure kinetics that we measure experimentally.« less

Non-native three-dimensional block copolymer morphologies

DOE PAGES

Rahman, Atikur; Majewski, Pawel W.; Doerk, Gregory; ...

2016-12-22

Self-assembly is a powerful paradigm, wherein molecules spontaneously form ordered phases exhibiting well-defined nanoscale periodicity and shapes. However, the inherent energy-minimization aspect of self-assembly yields a very limited set of morphologies, such as lamellae or hexagonally packed cylinders. Here, we show how soft self-assembling materials—block copolymer thin films—can be manipulated to form a diverse library of previously unreported morphologies. In this iterative assembly process, each polymer layer acts as both a structural component of the final morphology and a template for directing the order of subsequent layers. Specifically, block copolymer films are immobilized on surfaces, and template successive layers throughmore » subtle surface topography. As a result, this strategy generates an enormous variety of three-dimensional morphologies that are absent in the native block copolymer phase diagram.« less

Non-native three-dimensional block copolymer morphologies

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

Rahman, Atikur; Majewski, Pawel W.; Doerk, Gregory

Self-assembly is a powerful paradigm, wherein molecules spontaneously form ordered phases exhibiting well-defined nanoscale periodicity and shapes. However, the inherent energy-minimization aspect of self-assembly yields a very limited set of morphologies, such as lamellae or hexagonally packed cylinders. Here, we show how soft self-assembling materials—block copolymer thin films—can be manipulated to form a diverse library of previously unreported morphologies. In this iterative assembly process, each polymer layer acts as both a structural component of the final morphology and a template for directing the order of subsequent layers. Specifically, block copolymer films are immobilized on surfaces, and template successive layers throughmore » subtle surface topography. As a result, this strategy generates an enormous variety of three-dimensional morphologies that are absent in the native block copolymer phase diagram.« less

Influence of Processing Conditions on the Mechanical Behavior and Morphology of Injection Molded Poly(lactic-co-glycolic acid) 85:15

PubMed Central

Fancello, Eduardo Alberto

2017-01-01

Two groups of PLGA specimens with different geometries (notched and unnotched) were injection molded under two melting temperatures and flow rates. The mechanical properties, morphology at the fracture surface, and residual stresses were evaluated for both processing conditions. The morphology of the fractured surfaces for both specimens showed brittle and smooth fracture features for the majority of the specimens. Fracture images of the notched specimens suggest that the surface failure mechanisms are different from the core failure. Polarized light techniques indicated birefringence in all specimens, especially those molded with lower temperature, which suggests residual stress due to rapid solidification. DSC analysis confirmed the existence of residual stress in all PLGA specimens. The specimens molded using the lower injection temperature and the low flow rate presented lower loss tangent values according to the DMA and higher residual stress as shown by DSC, and the photoelastic analysis showed extensive birefringence. PMID:28848605

Stability diagrams for the surface patterns of GaN(0001bar) as a function of Schwoebel barrier height

NASA Astrophysics Data System (ADS)

Krzyżewski, Filip; Załuska-Kotur, Magdalena A.

2017-01-01

Height and type of Schwoebel barriers (direct or inverse) decides about the character of the surface instability. Different surface morphologies are presented. Step bunches, double steps, meanders, mounds and irregular patterns emerge at the surface as a result of step (Schwoebel) barriers at some temperature or miscut values. The study was carried out on the two-component kinetic Monte Carlo (kMC) model of GaN(0001bar) surface grown in nitrogen rich conditions. Diffusion of gallium adatoms over N-polar surface is slow and nitrogen adatoms are almost immobile. We show that in such conditions surfaces remain smooth when gallium adatoms diffuse in the presence of low inverse Schwoebel barrier. It is illustrated by adequate stability diagrams for surface morphologies.

Dynamics of yield-stress droplets: Morphology of impact craters

NASA Astrophysics Data System (ADS)

Neufeld, Jerome; Sohr, David; Ferrari, Leo; Dalziel, Stuart

2017-11-01

Yield strength can play an important role for the dynamics of droplets impacting on surfaces, whether at the industrial or planetary scale, and can capture a zoo of impact crater morphologies, from simple parabolic craters, to more complex forms with forms with, for example, multiple rings, central peaks. Here we show that the morphology of planetary impact craters can be reproduced in the laboratory using carbopol, a transparent yield-stress fluid, as both impactor and bulk fluid. Using high-speed video photography, we characterise the universal, transient initial excavation stage of impact and show the dependence of the subsequent relaxation to final crater morphology on impactor size, impact speed and yield stress. To further interrogate our laboratory impacts, we dye our impactor to map its final distribution and use particle tracking to determine the flow fields during impact and the maximal extent of the yield surface. We characterise the flow-fields induced during impact, and the maximal extent of the yield surface, by tracking particles within the bulk fluid and map the distribution of impactor and bulk by tracing the final distribution of dyed impactor. The results of laboratory impact droplets are used to infer the properties of planetary impactors, and aid in inter.

Optical properties and surface morphology studies of palladium contacts on mercuric iodide single crystals

NASA Astrophysics Data System (ADS)

George, M. A.; Azoulay, M.; Burger, A.; Biao, Y.; Silberman, E.; Nason, D.

1993-04-01

Palladium is chemically suitable for electric contacts on mercuric iodide detectors for photon and nuclear radiation detection, so the understanding of palladium contacts is important for fundamental and practical scientific purposes. A study has been conducted on the surface morphology of evaporated contacts using atomic force microscopy (AFM) and optical transmission and reflection. Evaporated palladium coatings are typically nonuniform and may deposit selectively on mercuric iodide surface defects. Reflection measurements show that coating thickness and surface treatment affect intensity, position, and shape of a reflected peak characteristic of the mercuric iodide structure. Results indicate that the band gap energy in the surface of the mercuric iodide is lowered by palladium contacts.

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

Lazauskas, A., E-mail: Algirdas.LAZAUSKAS@stud.ktu.lt; Guobienė, A., E-mail: Asta.GUOBIENE@ktu.lt; Prosyčevas, I., E-mail: IGORPROS@mail.ru

This work investigates water droplet behavior on superhydrophobic (water contact angle value of 162 ± 1°) SiO{sub 2} nanocomposite films subjected to repetitive icing/deicing treatments, changes in SiO{sub 2} nanocomposite film surface morphology and their non-wetting characteristics. During the experiment, water droplets on SiO{sub 2} nanocomposite film surface are subjected to a series of icing and deicing cycles in a humid (∼ 70% relative humidity) atmosphere and the resulting morphological changes are monitored and characterized using atomic force microscopy (AFM) and contact angle measurements. Our data show that the formation of the frozen or thawed water droplet, with no furthermore » shape change, on superhydrophobic SiO{sub 2} nanocomposite film, is obtained faster within each cycle as the number of the icing/deicing cycles increases. After 10 icing and deicing cycles, the superhydrophobic SiO{sub 2} nanocomposite film had a water contact angle value of 146 ± 2° which is effectively non-superhydrophobic. AFM analysis showed that the superhydrophobic SiO{sub 2} nanocomposite film surface area under the water droplet undergoes gradual mechanical damage during the repetitive icing/deicing cycles. We propose a possible mechanism of the morphological changes to the film surface that take place during the consecutive icing/deicing experiments. - Highlights: • Superhydrophobic film is subjected to repetitive icing/deicing treatments. • Water droplet shape transition is recorded and characterized thereafter. • Atomic force microscopy and contact angle measurements are performed. • The surface undergoes gradual mechanical damage during repetitive icing/deicing. • Mechanism for the observed surface morphological changes is suggested.« less

Morphology and Kinetics of Growth of CaCO3 Precipitates Formed in Saline Water at 30°C

NASA Astrophysics Data System (ADS)

Sui, Xin; Wang, Baohui; Wu, Haiming

2018-02-01

The crystallization kinetics and morphology of CaCO3 crystals precipitated from the high salinity oilfield water were studied. The crystallization kinetics measurements show that nucleation and nuclei growth obey the first order reaction kinetics. The induction period of precipitation is extended in the high salinity solutions. Morphological studies show that impurity ions remain mostly in the solution phase instead of filling the CaCO3 crystal lattice. The morphology of CaCO3 precipitates can be changed from a smooth surface (calcite) to rough spheres (vaterite), and spindle rod bundles, or spherical, ellipsoid, flowers, plates and other shapes (aragonite).

Surface Morphology and Tooth Adhesion of a Novel Nanostructured Dental Restorative Composite

PubMed Central

Salerno, Marco; Loria, Patrizia; Matarazzo, Giunio; Tomè, Francesco; Diaspro, Alberto; Eggenhöffner, Roberto

2016-01-01

Recently, a novel dental restorative composite based on nanostructured micro-fillers of anodic porous alumina has been proposed. While its bulk properties are promising thanks to decreased aging and drug delivery capabilities, its surface properties are still unknown. Here we investigated the surface morphology and the adhesion to tooth dentin of this composite as prepared. For comparison, we used two commercial composites: Tetric EVO Flow (Ivoclar) and Enamel HRi Plus (Micerium). The surface morphology was characterized by atomic force microscopy and the adhesion strength by tensile tests. The experimental composite is rougher than the commercial composites, with root mean square roughness of ~549 nm against 170–511 nm, and presents an adhesion strength of ~15 MPa against 19–21 MPa. These results show at the same time some proximity to the commercial composites, but also the need for optimization of the experimental material formulation. PMID:28773327

Facile and rapid synthesis of Pd nanodendrites for electrocatalysis and surface-enhanced Raman scattering applications

NASA Astrophysics Data System (ADS)

Kannan, Palanisamy; Dolinska, Joanna; Maiyalagan, Thandavarayan; Opallo, Marcin

2014-09-01

Numerous properties from metal nanostructures can be tuned by controlling both their size and shape. In particular, the latter is extremely important because the type of crystalline surface affects the surface electronic density. This paper describes a simple approach to the synthesis of highly-structured, anisotropic palladium nanostructured dendrites. They were obtained using an eco-friendly biomolecule 5-hydroxytryptophan, which acts as both a reducing and stabilizing agent. The growth mechanism is proposed for the evolution of dendrites morphology. It was found that the concentration of 5-hydroxytryptophan played a vital role on the morphology of the nanostructured Pd dendrites. This nanomaterial shows enhanced electrocatalytic performance towards the oxidation of formic acid, and it exhibits surface-enhanced Raman scattering properties towards the prostate specific antigen. These properties may be explored in fuel cells and biosensors, respectively.Numerous properties from metal nanostructures can be tuned by controlling both their size and shape. In particular, the latter is extremely important because the type of crystalline surface affects the surface electronic density. This paper describes a simple approach to the synthesis of highly-structured, anisotropic palladium nanostructured dendrites. They were obtained using an eco-friendly biomolecule 5-hydroxytryptophan, which acts as both a reducing and stabilizing agent. The growth mechanism is proposed for the evolution of dendrites morphology. It was found that the concentration of 5-hydroxytryptophan played a vital role on the morphology of the nanostructured Pd dendrites. This nanomaterial shows enhanced electrocatalytic performance towards the oxidation of formic acid, and it exhibits surface-enhanced Raman scattering properties towards the prostate specific antigen. These properties may be explored in fuel cells and biosensors, respectively. Electronic supplementary information (ESI) available. See DOI: 10.1039/c4nr02896a

Formation of Nanocones on Highly Oriented Pyrolytic Graphite by Oxygen Plasma

PubMed Central

Vesel, Alenka; Eleršič, Kristina; Modic, Martina; Junkar, Ita; Mozetič, Miran

2014-01-01

Improvement in hemocompatibility of highly oriented pyrolytic graphite (HOPG) by formation of nanostructured surface by oxygen plasma treatment is reported. We have showed that by appropriate fine tuning of plasma and discharge parameters we are able to create nanostructured surface which is densely covered with nanocones. The size of the nanocones strongly depended on treatment time. The optimal results in terms of material hemocompatibility were obtained after treatment with oxygen plasma for 15 s, when both the nanotopography and wettability were the most favorable, since marked reduction in adhesion and activation of platelets was observed on this surface. At prolonged treatment times, the rich surface topography was lost and thus also its antithrombogenic properties. Chemical composition of the surface was always more or less the same, regardless of its morphology and height of the nanocones. Namely, on all plasma treated samples, only a few atomic percent of oxygen was found, meaning that plasma caused mostly etching, leading to changes in the surface morphology. This indicates that the main preventing mechanism against platelets adhesion was the right surface morphology. PMID:28788553

Thickness-dependent spontaneous dewetting morphology of ultrathin Ag films.

PubMed

Krishna, H; Sachan, R; Strader, J; Favazza, C; Khenner, M; Kalyanaraman, R

2010-04-16

We show here that the morphological pathway of spontaneous dewetting of ultrathin Ag films on SiO2 under nanosecond laser melting is dependent on film thickness. For films with thickness h of 2 nm < or = h < or = 9.5 nm, the morphology during the intermediate stages of dewetting consisted of bicontinuous structures. For films with 11.5 nm < or = h < or = 20 nm, the intermediate stages consisted of regularly sized holes. Measurement of the characteristic length scales for different stages of dewetting as a function of film thickness showed a systematic increase, which is consistent with the spinodal dewetting instability over the entire thickness range investigated. This change in morphology with thickness is consistent with observations made previously for polymer films (Sharma and Khanna 1998 Phys. Rev. Lett. 81 3463-6; Seemann et al 2001 J. Phys.: Condens. Matter 13 4925-38). Based on the behavior of free energy curvature that incorporates intermolecular forces, we have estimated the morphological transition thickness for the intermolecular forces for Ag on SiO2. The theory predictions agree well with observations for Ag. These results show that it is possible to form a variety of complex Ag nanomorphologies in a consistent manner, which could be useful in optical applications of Ag surfaces, such as in surface enhanced Raman sensing.

Effects of scaffold surface morphology on cell adhesion and survival rate in vitreous cryopreservation of tenocyte-scaffold constructs

NASA Astrophysics Data System (ADS)

Wang, Zhi; Qing, Quan; Chen, Xi; Liu, Cheng-Jun; Luo, Jing-Cong; Hu, Jin-Lian; Qin, Ting-Wu

2016-12-01

The purpose of this study was to investigate the effects of scaffold surface morphology on cell adhesion and survival rate in vitreous cryopreservation of tenocyte-scaffold constructs. Tenocytes were obtained from tail tendons of rats. Polydimethylsiloxane (PDMS) was used to fabricate three types of scaffolds with varying surface morphological characteristics, i.e., smooth, micro-grooved, and porous surfaces, respectively. The tenocytes were seeded on the surfaces of the scaffolds to form tenocyte-scaffold constructs. The constructs were cryopreserved in a vitreous cryoprotectant (CPA) with a multi-step protocol. The cell adhesion to scaffolds was observed with electronic scanning microscopy (SEM). The elongation index of the living tenocytes and ratio of live/dead cell number were examined based on a live/dead dual fluorescent staining technique, and the survival rate of tenocytes was studied with flow cytometry (FC). The results showed the shapes of tenocytes varied between the different groups: flat or polygonal (on smooth surface), spindle (on micro-grooved surface), and spindle or ellipse (on porous surface). After thawing, the porous surface got the most living tenocytes and a higher survival rate, suggesting its potential application for vitreous cryopreservation of engineered tendon constructs.

Water striders adjust leg movement speed to optimize takeoff velocity for their morphology.

PubMed

Yang, Eunjin; Son, Jae Hak; Lee, Sang-Im; Jablonski, Piotr G; Kim, Ho-Young

2016-12-07

Water striders are water-walking insects that can jump upwards from the water surface. Quick jumps allow striders to avoid sudden dangers such as predators' attacks, and therefore their jumping is expected to be shaped by natural selection for optimal performance. Related species with different morphological constraints could require different jumping mechanics to successfully avoid predation. Here we show that jumping striders tune their leg rotation speed to reach the maximum jumping speed that water surface allows. We find that the leg stroke speeds of water strider species with different leg morphologies correspond to mathematically calculated morphology-specific optima that maximize vertical takeoff velocity by fully exploiting the capillary force of water. These results improve the understanding of correlated evolution between morphology and leg movements in small jumping insects, and provide a theoretical basis to develop biomimetic technology in semi-aquatic environments.

Water striders adjust leg movement speed to optimize takeoff velocity for their morphology

NASA Astrophysics Data System (ADS)

Yang, Eunjin; Son, Jae Hak; Lee, Sang-Im; Jablonski, Piotr G.; Kim, Ho-Young

2016-12-01

Water striders are water-walking insects that can jump upwards from the water surface. Quick jumps allow striders to avoid sudden dangers such as predators' attacks, and therefore their jumping is expected to be shaped by natural selection for optimal performance. Related species with different morphological constraints could require different jumping mechanics to successfully avoid predation. Here we show that jumping striders tune their leg rotation speed to reach the maximum jumping speed that water surface allows. We find that the leg stroke speeds of water strider species with different leg morphologies correspond to mathematically calculated morphology-specific optima that maximize vertical takeoff velocity by fully exploiting the capillary force of water. These results improve the understanding of correlated evolution between morphology and leg movements in small jumping insects, and provide a theoretical basis to develop biomimetic technology in semi-aquatic environments.

A comparative scanning electron microscopy study between hand instrument, ultrasonic scaling and erbium doped:Yttirum aluminum garnet laser on root surface: A morphological and thermal analysis

PubMed Central

Mishra, Mitul Kumar; Prakash, Shobha

2013-01-01

Background and Objectives: Scaling and root planing is one of the most commonly used procedures for the treatment of periodontal diseases. Removal of calculus using conventional hand instruments is incomplete and rather time consuming. In search of more efficient and less difficult instrumentation, investigators have proposed lasers as an alternative or as adjuncts to scaling and root planing. Hence, the purpose of the present study was to evaluate the effectiveness of erbium doped: Yttirum aluminum garnet (Er:YAG) laser scaling and root planing alone or as an adjunct to hand and ultrasonic instrumentation. Subjects and Methods: A total of 75 freshly extracted periodontally involved single rooted teeth were collected. Teeth were randomly divided into five treatment groups having 15 teeth each: Hand scaling only, ultrasonic scaling only, Er:YAG laser scaling only, hand scaling + Er:YAG laser scaling and ultrasonic scaling + Er:YAG laser scaling. Specimens were subjected to scanning electron microscopy and photographs were evaluated by three examiners who were blinded to the study. Parameters included were remaining calculus index, loss of tooth substance index, roughness loss of tooth substance index, presence or absence of smear layer, thermal damage and any other morphological damage. Results: Er:YAG laser treated specimens showed similar effectiveness in calculus removal to the other test groups whereas tooth substance loss and tooth surface roughness was more on comparison with other groups. Ultrasonic treated specimens showed better results as compared to other groups with different parameters. However, smear layer presence was seen more with hand and ultrasonic groups. Very few laser treated specimens showed thermal damage and morphological change. Interpretation and Conclusion: In our study, ultrasonic scaling specimen have shown root surface clean and practically unaltered. On the other hand, hand instrument have produced a plane surface, but removed more tooth structure. The laser treated specimens showed rough surfaces without much residual deposit or any other sign of morphological change. PMID:24015009

Morphology of Er:YAG-laser-treated root surfaces

NASA Astrophysics Data System (ADS)

Keller, Ulrich; Stock, Karl; Hibst, Raimund

1997-12-01

From previous studies it could be demonstrated that an efficient ablation of dental calculus is possible using an Er:YAG laser with a special contact fiber tip. After improving of the design and the efficiency of light transmission of the contact tip laser treated tooth root surfaces were investigated due to morphological changes in comparison to conventional root scaling and planing. Surface modifications were observed histologically under the light microscope and by means of a Scanning Electron Microscope. During laser treatment the intrapulpal temperature increase was measured. The results show that the improved contact tip a microstructured surface can be generated, which shows no signs of thermal effects even when a laser pulse repetition rate of 15 Hz was used. Temperature increase was limited to 4 K at a repetition rate of 10 Hz and to 5.5 K at a repetition rate of 15 Hz.

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

Guo, Wei; Reese, Cassandra M.; Xiong, Li

We report a simple route to engineer ultrathin polymer brush surfaces with wrinkled morphologies using postpolymerization modification (PPM), where the length scale of the buckled features can be tuned using PPM reaction time. Here, we show that partial crosslinking of the outer layer of the polymer brush under poor solvent conditions is critical to obtain wrinkled morphologies upon swelling.

Electroless controllable growth of ZnO films and their morphology-dependent antimicrobial properties.

PubMed

Ruíz-Gómez, M A; Figueroa-Torres, M Z; Alonso-Lemus, I L; Vega-Becerra, O E; González-López, J R; Zaldívar-Cadena, A A

2018-04-05

An electroless deposition process was used to synthesize with a controlled morphology, polycrystalline ZnO on glass substrates as antimicrobial coatings. The influence of deposition temperature (T dep ) on the physicochemical and antimicrobial properties of the ZnO films was analyzed. The results indicated that a change in deposition temperature greatly affected the morphology and the degree of crystallinity of the films. Scanning electron microscope images show that the film surface is porous at a deposition temperature of 40 and 50 °C, whereas hexagonal-plate shaped morphology predominated at 60 °C and finally at 70 and 80 °C the films consisted of rod-like particles. The films showed good transparency in the visible region. All ZnO films presented notable antimicrobial activity against the gram-negative bacteria Escherichia coli (E. coli) and the gram-positive Staphylococcus aureus (S. aureus). It was found that the antimicrobial efficiency is strongly dependent on morphology and structural properties. The best antimicrobial performance was recorded for the films consisting of rod-like morphology with a high degree of crystallinity. The procedure used in this investigation is strongly recommended for the development of functional surfaces. Copyright © 2017 Elsevier B.V. All rights reserved.

Three-dimensional OCT based guinea pig eye model: relating morphology and optics.

PubMed

Pérez-Merino, Pablo; Velasco-Ocana, Miriam; Martinez-Enriquez, Eduardo; Revuelta, Luis; McFadden, Sally A; Marcos, Susana

2017-04-01

Custom Spectral Optical Coherence Tomography (SOCT) provided with automatic quantification and distortion correction algorithms was used to measure the 3-D morphology in guinea pig eyes (n = 8, 30 days; n = 5, 40 days). Animals were measured awake in vivo under cyclopegia. Measurements showed low intraocular variability (<4% in corneal and anterior lens radii and <8% in the posterior lens radii, <1% interocular distances). The repeatability of the surface elevation was less than 2 µm. Surface astigmatism was the individual dominant term in all surfaces. Higher-order RMS surface elevation was largest in the posterior lens. Individual surface elevation Zernike terms correlated significantly across corneal and anterior lens surfaces. Higher-order-aberrations (except spherical aberration) were comparable with those predicted by OCT-based eye models.

Studies on the nematode; Moaciria icosiensis (Seurat, 1917) from Chalcides ocellatus (Forsk.) in Egypt.

PubMed

al-Deen, A; al-Shareef, M F

1996-12-01

With the aid of scanning electron microscopy certain morphological features (e.g.lateral alae, posterior end of male and cuticular surface) are used as principal pilars in the description of the nematode Moaciria icosiensis (Seurat, 1917) from Chalcides ocellatus (Forsk). Cuticular surface is distinguished by minute striations. Lateral alae are smooth and showing undulation. The posterior end of the male is curved and carries specific papillae. These morphological features are specific and aid in proper identification of Moaciria icosiensis.

Surface Morphology of Undoped and Doped ZnSe Films

NASA Technical Reports Server (NTRS)

George, T.; Hayes, M.; Chen, H.; Chattopadhyay, K.; Thomas E.; Morgan, S.; Burger, A.

1998-01-01

Rare-earth doped ions in polar II-VI semiconductors have recently played an important role in the optical properties of materials and devices. In this study, undoped ZnSe and erbium doped ZnSe films were grown by radio frequency (RF) magnetron sputtering method. Atomic Force Microscopy (AFM) was used together with optical microscopy and UV-Vis spectroscopy to characterize the films. Doped samples were found to have higher surface roughness and quite different surface morphology compared to that of undoped samples. The grown films generally show a relatively smooth and uniform surface indicating that they are of overall good quality. The impact of plasma etching on ZnSe:Er film examined under AFM is also discussed.

Droplet sliding on inclined superhydrophobic surfaces: the effect of anisotropic contact line

NASA Astrophysics Data System (ADS)

Jiang, Youhua; Cao, Lile; Guo, Zongqi; Choi, Chang-Hwan

2017-11-01

Although the effects of solid structures on droplet retention on superhydrophobic surfaces have been studied extensively, the investigation has been restricted to the sessile droplets on horizontal surfaces where the contact line motions are axisymmetric or isotropic (either advancing or receding). In the droplet retention on inclined surfaces, the contact line motions are asymmetric or anisotropic; the advancing and receding motions coexist. In this study, we investigate the correlation between the droplet boundary pinning and the surface morphology on inclined superhydrophobic surfaces. The evolution of the droplet contact angle and width show contrary behaviors between pillar- and pore-structured surfaces due to the distinctive microscopic contact line motions. Therefore, the visualizations of the contact line motions at different locations of the boundary on inclined superhydrophobic surfaces are performed and the averaged contact line density of the boundary is quantified. The result shows that the droplet retentive force monotonously increase with the increase in contact line density, regardless of the surface morphological types, dimensions, or the direction of contact line motion (advancing, receding, or both). The result indicates that the droplet retentive force on superhydrophobic surfaces is mainly determined by the contact line density, regardless of the isotropy of the contact line.

Measuring the specific surface area of natural and manmade glasses: effects of formation process, morphology, and particle size

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

Papelis, Charalambos; Um, Wooyong; Russel, Charles E.

2003-03-28

The specific surface area of natural and manmade solid materials is a key parameter controlling important interfacial processes in natural environments and engineered systems, including dissolution reactions and sorption processes at solid-fluid interfaces. To improve our ability to quantify the release of trace elements trapped in natural glasses, the release of hazardous compounds trapped in manmade glasses, or the release of radionuclides from nuclear melt glass, we measured the specific surface area of natural and manmade glasses as a function of particle size, morphology, and composition. Volcanic ash, volcanic tuff, tektites, obsidian glass, and in situ vitrified rock were analyzed.more » Specific surface area estimates were obtained using krypton as gas adsorbent and the BET model. The range of surface areas measured exceeded three orders of magnitude. A tektite sample had the highest surface area (1.65 m2/g), while one of the samples of in situ vitrified rock had the lowest surf ace area (0.0016 m2/g). The specific surface area of the samples was a function of particle size, decreasing with increasing particle size. Different types of materials, however, showed variable dependence on particle size, and could be assigned to one of three distinct groups: (1) samples with low surface area dependence on particle size and surface areas approximately two orders of magnitude higher than the surface area of smooth spheres of equivalent size. The specific surface area of these materials was attributed mostly to internal porosity and surface roughness. (2) samples that showed a trend of decreasing surface area dependence on particle size as the particle size increased. The minimum specific surface area of these materials was between 0.1 and 0.01 m2/g and was also attributed to internal porosity and surface roughness. (3) samples whose surface area showed a monotonic decrease with increasing particle size, never reaching an ultimate surface area limit within the particle size range examined. The surface area results were consistent with particle morphology, examined by scanning electron microscopy, and have significant implications for the release of radionuclides and toxic metals in the environment.« less

Experimental evaluation of a new morphological approximation of the articular surfaces of the ankle joint.

PubMed

Belvedere, Claudio; Siegler, Sorin; Ensini, Andrea; Toy, Jason; Caravaggi, Paolo; Namani, Ramya; Giannini, Giulia; Durante, Stefano; Leardini, Alberto

2017-02-28

The mechanical characteristics of the ankle such as its kinematics and load transfer properties are influenced by the geometry of the articulating surfaces. A recent, image-based study found that these surfaces can be approximated by a saddle-shaped, skewed, truncated cone with its apex oriented laterally. The goal of this study was to establish a reliable experimental technique to study the relationship between the geometry of the articular surfaces of the ankle and its mobility and stability characteristics and to use this technique to determine if morphological approximations of the ankle surfaces based on recent discoveries, produce close to normal behavior. The study was performed on ten cadavers. For each specimen, a process based on medical imaging, modeling and 3D printing was used to produce two subject specific artificial implantable sets of the ankle surfaces. One set was a replica of the natural surfaces. The second approximated the ankle surfaces as an original saddle-shaped truncated cone with apex oriented laterally. Testing under cyclic loading conditions was then performed on each specimen following a previously established technique to determine its mobility and stability characteristics under three different conditions: natural surfaces; artificial surfaces replicating the natural surface morphology; and artificial approximation based on the saddle-shaped truncated cone concept. A repeated measure analysis of variance was then used to compare between the three conditions. The results show that (1): the artificial surfaces replicating natural morphology produce close to natural mobility and stability behavior thus establishing the reliability of the technique; and (2): the approximated surfaces based on saddle-shaped truncated cone concept produce mobility and stability behavior close to the ankle with natural surfaces. Copyright © 2017 Elsevier Ltd. All rights reserved.

Influence of surface microroughness by plasma deposition and chemical erosion followed by TiO2 coating upon anticoagulation, hydrophilicity, and corrosion resistance of NiTi alloy stent.

PubMed

Wang, Gui-Xue; Shen, Yang; Zhang, He; Quan, Xue-Jun; Yu, Qing-Song

2008-06-15

Two different surface modification techniques were used to change the surface morphology and roughness of stents at the micrometer level, and eventually improve their surface adhesion properties with respect to endothelial cells. One was chemical erosion followed by sol-gel TiO(2) coating, and the other was low temperature gas plasma deposition. After surface modification, the biocompatibility including the anticoagulation properties, hydrophilicity, and corrosion resistance of these stents was evaluated. It was found that both techniques could change the surface morphology of the stents with microroughness. In comparison with the control, the treated NiTi alloy intravascular stents showed increased surface hydrophilicity and enhanced anticoagulation properties. However, the corrosion properties of the stents were not improved significantly.

The effects of electrospun substrate-mediated cell colony morphology on the self-renewal of human induced pluripotent stem cells.

PubMed

Maldonado, Maricela; Wong, Lauren Y; Echeverria, Cristina; Ico, Gerardo; Low, Karen; Fujimoto, Taylor; Johnson, Jed K; Nam, Jin

2015-05-01

The development of xeno-free, chemically defined stem cell culture systems has been a primary focus in the field of regenerative medicine to enhance the clinical application of pluripotent stem cells (PSCs). In this regard, various electrospun substrates with diverse physiochemical properties were synthesized utilizing various polymer precursors and surface treatments. Human induced pluripotent stem cells (IPSCs) cultured on these substrates were characterized by their gene and protein expression to determine the effects of the substrate physiochemical properties on the cells' self-renewal, i.e., proliferation and the maintenance of pluripotency. The results showed that surface chemistry significantly affected cell colony formation via governing the colony edge propagation. More importantly, when surface chemistry of the substrates was uniformly controlled by collagen conjugation, the stiffness of substrate was inversely related to the sphericity, a degree of three dimensionality in colony morphology. The differences in sphericity subsequently affected spontaneous differentiation of IPSCs during a long-term culture, implicating that the colony morphology is a deciding factor in the lineage commitment of PSCs. Overall, we show that the capability of controlling IPSC colony morphology by electrospun substrates provides a means to modulate IPSC self-renewal. Copyright © 2015 Elsevier Ltd. All rights reserved.

Phase transition of LB films of mixed diblock copolymer at the air/water interface

NASA Astrophysics Data System (ADS)

Seo, Y. S.; Kim, K. S.; Samuilov, V.; Rafailovich, M. H.; Sokolov, J.; Lammertink, Rob G. H.; Vancso, G. J.

2000-03-01

We have studied the morphology of Langmuir blodgett films at the air/water interface of mixed diblock copolymer films. Solutions of poly(styrene-b-ferrocenyldimethylsilane) and PS-b-P2VP mixed in a ratio of 20/80 in chloroform were spread at the air/water interface. The morphology of the films was studied with AFM as a function of the surface pressure and the diblock copolymer molecular weight. The results show that the two diblock copolymers can be induced to mix at the air/water interface with increasing surface pressure. A reversible transition from spherical to cylindrical morphologies is induced in the mixture which can not be observed in films formed of the two components separately. The effective surface phase diagram as a function of block copolymer composition and pressure will be presented.

Surface morphological properties of Ag-Al2O3 nanocermet layers using dip-coating technique

NASA Astrophysics Data System (ADS)

Muhammad, Nor Adhila; Suhaimi, Siti Fatimah; Zubir, Zuhana Ahmad; Daud, Sahhidan

2017-12-01

Ag-Al2O3 nanocermet layer was deposited on Cu coated glass substrate using dip-coating technique. The aim of this study was to observe the surface morphology properties of Ag-Al2O3 nanocermet layers after annealing process at 350°C in H2. The surface morphology of Ag-Al2O3 nanocermet will be characterized by Scanning Electron Microscopy (SEM), Atomic Force Microscopy (AFM) and X-Ray Diffractometer (XRD), respectively. The results show that nearly isolated Ag particles having a large and small size were present in the Al2O3 dielectric matrix after annealing process. The face centered cubic crystalline structure of Ag nanoparticles inclusion in the amorphous alumina dielectric matrix was confirmed using XRD pattern and supported by EDX spectra analysis.

Correlating yeast cell stress physiology to changes in the cell surface morphology: atomic force microscopic studies.

PubMed

Canetta, Elisabetta; Walker, Graeme M; Adya, Ashok K

2006-07-06

Atomic Force Microscopy (AFM) has emerged as a powerful biophysical tool in biotechnology and medicine to investigate the morphological, physical, and mechanical properties of yeasts and other biological systems. However, properties such as, yeasts' response to environmental stresses, metabolic activities of pathogenic yeasts, cell-cell/cell-substrate adhesion, and cell-flocculation have rarely been investigated so far by using biophysical tools. Our recent results obtained by AFM on one strain each of Saccharomyces cerevisiae and Schizosaccharomyces pombe show a clear correlation between the physiology of environmentally stressed yeasts and the changes in their surface morphology. The future directions of the AFM related techniques in relation to yeasts are also discussed.

[Three-dimensional evaluation of condylar morphology remodeling after orthognathic surgery in mandibular retrognathism by cone-beam computed tomography].

PubMed

Chen, Shuo; Liu, Xiao-jing; Li, Zi-li; Liang, Cheng; Wang, Xiao-xia; Fu, Kai-yuan; Yi, Biao

2015-08-18

To evaluate the effect of orthognathic surgery on condylar morphology changes by comparing three-dimension surface reconstructions of condyles using cone-beam computed tomography (CBCT) data. In the study, 18 patients with mandible retrognathism deformities were included and CBCT data of 36 temporomandibular joints were collected before surgery and 12 months after surgery. Condyles were reconstructed and superimposed pre- and post-operatively to compare the changes of condylar surfaces. One-sample t test and χ2 test were performed for the analysis of three-dimension metric measurement and condylar head remodeling signs. P<0.05 was considered significant. The root-mean-square (RMS) of condylar surface changes before and after the surgery was (0.37±0.11) mm, which was significant statistically (P<0.05). The distribution of condylar remodeling signs showed significant difference (P<0.05). Bone resorption occurred predominantly in the posterior area of condylar head and bone formation occurred mainly in the anterior area. Three-dimension superimposition method based on CBCT data showed that condylar morphology had undergone remodeling after mandibular advancement.

Morphology Tuning of Strontium Tungstate Nanoparticles

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

Joseph, S.; George, T.; George, K. C.

2007-08-22

Strontium tungstate nanocrystals in two different morphologies are successfully synthesized by controlled precipitation in aqueous and in poly vinyl alcohol (PVA) medium. Structural characterizations are carried out by XRD and SEM. The average particle size calculated for the SrWO4 prepared in the two different solvents ranges 20-24 nm. The SEM pictures show that the surface morphologies of the SrWO4 nanoparticles in aqueous medium resemble mushroom and the SrWO4 nanoparticles in PVA medium resemble cauliflower. Investigations on the room temperature luminescent properties of the strontium tungstate nanoparticles prepared in aqueous and PVA medium shows strong emissions around 425 nm.

Morphological driven photocatalytic activity of ZnO nanostructures

NASA Astrophysics Data System (ADS)

Abbas, Khaldoon N.; Bidin, Noriah

2017-02-01

Using a simple combination of pulse laser ablation in liquid and hydrothermal (PLAL-H) approaches, we control the morphology of ZnO nanostructures (ZNSs) to determine the feasibility of their photocatalytic efficacy. These ZNSs are deposited on Si (100) substrates and two different morphologies are achieved. In this synergistic approach, PLAL synthesized NSs are used as a nutrient solution with different pH for further hydrothermal treatment at 110 °C under varying growth time (5, 30 and 60 min). Surface morphology, structure, composition, and optical characteristics of the prepared ZNSs are determined using FESEM, XRD, FTIR and Photoluminescence (PL) and UV-vis absorption measurements. The morphology revealed remarkable transformation from nanorods (NRs)/nanoflowers (NFs) (at pH 7.6) to nanoparticles (NPs)-like (at pH 10.5) structure. XRD patterns showed better polycrystallinity for NPs with enlarged band gap than NR/NF-like structures. Both PL and UV-vis spectral analysis of ZNPs exhibited higher surface area and deep level defects density dependent morphology, where the nutrient pH and growth time variation are found to play a significant role towards structural evolution. Furthermore, the photocatalytic activities of, such ZNSs are evaluated via sunlight driven photo-degradation of methylene blue (MB) dye. The photocatalytic efficiency of ZNPs is demonstrated to be much superior (97.4%) than ZNRs/ZNFs-like morphology (86%). Such enhanced photocatalytic activities of as-synthesized ZNPs is attributed to the synergism of the improved surface area and defects density, which is useful for promoting the adsorption of the MB dye and suppressed surface recombination of photo-generated charge carriers.

Studies on morphology of Langmuir-Blodgett films of stearic acid deposited with different orientation of substrates with respect to compression

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

Choudhary, Keerti; Manjuladevi, V.; Gupta, R. K., E-mail: raj@pilani.bits-pilani.ac.in

2016-05-06

The Langmuir monolayer at an air-water interface shows remarkably different surface pressure – area isotherm, when measured with the surface normal of a Wilhemly plate parallel or perpendicular to the direction of compression of the monolayer. Such difference arises due to difference in stress exerted by the monolayer on the plate in different direction. In this article, we report the effect of changing the direction of substrate normal with respect to the compression of the monolayer during Langmuir-Blodgett (LB) film deposition on the morphology of the films. The morphology of the LB film of stearic acid was studied using anmore » atomic force microscope (AFM). The morphology of the LB films was found to be different due to difference in the stress in different directions.« less

Durability of Pt-Co Alloy Polymer Electrolyte Fuel Cell Cathode Catalysts under Accelerated Stress Tests

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

Papadias, D. D.; Ahluwalia, R. K.; Kariuki, N.

The durability of Pt-Co alloy cathode catalysts supported on high surface area carbon is investigated by subjecting them to accelerated stress tests (ASTs). The catalysts had different initial Co contents and nanoparticle morphologies: a “spongy” porous morphology for the high-Co (H) content catalyst, and a fully alloyed crystalline morphology for the medium-Co (M) and low-Co (L) content catalysts. The specific activity of the catalysts depends on their initial Co content, morphology and nanoparticle size, and remained higher than 1000 μA/cm 2-Pt after 27–50% Co loss. The H-catalyst electrode showed the smallest kinetic overpotentials (η c s) due to higher initialmore » Pt loading than the other two electrodes, but it had the fastest increase in ηcs with AST cycling due to lower Co retention; the L-catalyst electrode showed higher η c s due to a lower initial Pt loading, but had a smaller increase in η c s with aging due to higher Co retention; the M-catalyst electrode showed a similar increase in η c s with aging, but this increase was due to the combined effects of Co dissolution and electrochemically active surface area (ECSA) loss. In conclusion, the modeled increase in mass transfer overpotentials with aging correlates with the initial Pt loading, ECSA loss and the initial catalyst morphology« less

Durability of Pt-Co Alloy Polymer Electrolyte Fuel Cell Cathode Catalysts under Accelerated Stress Tests

DOE PAGES

Papadias, D. D.; Ahluwalia, R. K.; Kariuki, N.; ...

2018-03-17

The durability of Pt-Co alloy cathode catalysts supported on high surface area carbon is investigated by subjecting them to accelerated stress tests (ASTs). The catalysts had different initial Co contents and nanoparticle morphologies: a “spongy” porous morphology for the high-Co (H) content catalyst, and a fully alloyed crystalline morphology for the medium-Co (M) and low-Co (L) content catalysts. The specific activity of the catalysts depends on their initial Co content, morphology and nanoparticle size, and remained higher than 1000 μA/cm 2-Pt after 27–50% Co loss. The H-catalyst electrode showed the smallest kinetic overpotentials (η c s) due to higher initialmore » Pt loading than the other two electrodes, but it had the fastest increase in ηcs with AST cycling due to lower Co retention; the L-catalyst electrode showed higher η c s due to a lower initial Pt loading, but had a smaller increase in η c s with aging due to higher Co retention; the M-catalyst electrode showed a similar increase in η c s with aging, but this increase was due to the combined effects of Co dissolution and electrochemically active surface area (ECSA) loss. In conclusion, the modeled increase in mass transfer overpotentials with aging correlates with the initial Pt loading, ECSA loss and the initial catalyst morphology« less

Effect of copper concentration in the electrolyte on the surface morphology and the microstructure of CuInSe2 films

NASA Astrophysics Data System (ADS)

Hung, Pin-Kun; Kuo, Ting-Wei; Huang, Kuo-Chan; Wang, Na-Fu; Hsieh, Po-Tsung; Houng, Mau-Phon

2012-07-01

The surface morphology and the microstructure of CuInSe2 precursor films have been investigated by co-electrodeposition with different [Cu2+] concentrations from 2 mM to 4 mM. The characteristic of the precursor films was examined using field-emission scanning electron microscopy (FE-SEM), energy dispersive X-ray spectroscopy (EDS), glancing incidence angle X-ray diffraction (GIXRD) and micro-Raman spectrometer, respectively. The surface morphology of the precursor films become more smoother and compact with choice of appropriate [Cu2+] concentration (3-3.5 mM) in the electrolyte. The relation between surface morphology and [Cu2+] concentration is also considered in terms of electrodeposition nucleation mechanisms using the mathematical models of Scharifker and Hills. It is suggested that the higher [Cu2+] concentrations can provide more numbers of nucleation sites on the surface of the electrode. Results simulated from the Rietveld refinement method suggest that decreasing dCusbnd Se is related to charge transfer from interstitial copper atoms and can affect the film microstructure. Micro-Raman spectrum also shows that the excess Cu atoms in the precursor films does not contribute significantly to large amounts of secondary phases but rather exists in the crystallite structure as other defect types.

An investigation of the degradation of Fluorinated Ethylene Propylene (FEP) copolymer thermal blanketing materials aboard LDEF in the laboratory

NASA Technical Reports Server (NTRS)

Stiegman, A. E.; Brinza, David E.; Anderson, Mark S.; Minton, Timothy K.; Laue, Eric G.; Liang, Ranty H.

1991-01-01

Samples of fluorinated ethylene propylene copolymer thermal blanketing material, recovered from the Long Duration Exposure Facility (LDEF), were investigated to determine the nature and the extent of degradation due to exposure to the low-Earth-orbit environment. Samples recovered from the ram-facing direction of LDEF, which received vacuum-ultraviolet (VUV) radiation and atomic-oxygen impingement, and samples from the trailing edge, which received almost exclusively VUV exposure, were investigated by scanning electron microscopy and atomic force microscopy. The most significant result of this investigation was found on samples that received only VUV exposure. These samples possessed a hard, embrittled surface layer that was absent from the atomic-oxygen exposed sample and from unexposed control samples. This surface layer is believed to be responsible for the 'synergistic' effect between VUV and atomic oxygen. Overall, the investigation revealed dramatically different morphologies for the two samples. The sample receiving both atomic-oxygen and VUV exposure was deeply eroded and had a characteristic 'rolling' surface morphology, while the sample that received only VUV exposure showed mild erosion and a surface morphology characterized by sharp high-frequency peaks. The morphologies observed in the LDEF samples, including the embrittled surface layer, were successfully duplicated in the laboratory.

Effects of aging procedures on the molecular, biochemical, morphological, and mechanical properties of vacuum-formed retainers.

PubMed

Ahn, Hyo-Won; Ha, Hye-Ryun; Lim, Ho-Nam; Choi, Samjin

2015-11-01

The influence of intraoral exposure procedures on the physical characteristics of thermoplastic vacuum-formed retainers (VFRs) is still unclear. The effects of thermoforming and intraoral use on the molecular, chemical, morphological, and mechanical properties of thermoplastic VFRs were investigated. VFRs with a 0.8-mm-thick thermoplastic PETG sheet acquired from 48 patients were investigated with two aging procedures, including vacuum forming and intraoral exposure, for 2-week and 6-month. Eight evaluating sites for thermoplastic VFRs were assessed with seven analytical techniques. LM, SEM, and AFM microscopic findings showed that the surface characteristics increased with increasing in vivo exposure time (a four-fold increase) and varied depending on the sites evaluated (an occlusal surface). Raman and EDX spectroscopic findings showed that aging procedures led to a significant change in the molecular composition of VFRs, leading to a decrease in the composition rate of carbon (C) and the presence of silicon (Si), phosphorus (P), and calcium (Ca). Compressive strength and tensile tests showed that aging procedures led to a significant increase (P<0.01) in ultimate tensile strength, elastic modulus, the stored energy at a 6-mm deflection (u6 mm), and the compressed load at a 3-mm deflection (σ3 mm). Thermoforming led to a smoother surface and no crystallization of PETG sheets. Intraoral exposure accelerated changes in surface morphology, tensile strength, and elastic modulus of VFRs. This change was site-specific and enhanced with an increase in intraoral exposure time. Therefore, thermoforming and in vivo oral exposure procedures led to the molecular, morphological, and mechanical properties of thermoplastic VFRs. Copyright © 2015 Elsevier Ltd. All rights reserved.

The ultrastructural surface morphology of oral cancer cells and keratinocytes after exposure to chitosan

NASA Astrophysics Data System (ADS)

Fatimah; Sarsito, A. S.; Wimardhani, Y. S.

2017-08-01

Low-molecular-weight chitosan (LMWC) has the same selective cytotoxic effects on oral cancer cells as cisplatin. The cell deaths caused by the anticancer characteristics of chitosan show that apoptosis is not the death pathway of the primary cells involved. The interactions between LMWC and the cells need to be explored. The objective of this study was to compare the ultrastructural morphology of oral Squamous Cell Carcinoma (SCC Ca)-922 and noncancer keratinocyte HaCaT cell lines after exposure to LMWC and cisplatin. The cells were treated with LMWC and cisplatin, and their ultrastructural morphology was analyzed using scanning electron micrographs. Features of early apoptosis, seen as the loss of microvilli, were detected in the LMWC-exposed Ca9-22 cells, and there was a material surrounding the cells. In contrast, the LMWC-exposed HaCaT cells showed no changes related to apoptosis. The results were the opposite when cisplatin was used. This study confirms that there are differences in the ultrastructural surface morphology of LMWC-exposed and cisplatin-exposed oral cancer cells and keratinocytes that could be correlated with their biological activity.

A novel approach to enhancement of surface properties of CdO films by using surfactant: dextrin

NASA Astrophysics Data System (ADS)

Sahin, Bünyamin; Bayansal, Fatih; Yüksel, Mustafa

2015-12-01

We studied the effect of an organic surfactant, dextrin, concentration on structural, morphological and optical properties of nanostructured CdO films deposited on glass substrates by using an easy and low-cost SILAR method. Microstructures of the nanostructured CdO films were optimized by adjusting dextrin concentration. XRD, SEM and UV-Vis Spectroscopy were used to study phase structure, surface morphology and optical properties of CdO films. Furthermore, effects of dextrin concentration on the surface roughness characteristics of CdO samples were reported. The results showed that the presence of organic surfactant highly affected the physical properties of CdO nanomaterials.

Surface modification of an Mg-1Ca alloy to slow down its biocorrosion by chitosan.

PubMed

Gu, X N; Zheng, Y F; Lan, Q X; Cheng, Y; Zhang, Z X; Xi, T F; Zhang, D Y

2009-08-01

The surface morphologies before and after immersion corrosion test of various chitosan-coated Mg-1Ca alloy samples were studied to investigate the effect of chitosan dip coating on the slowdown of biocorrosion. It showed that the corrosion resistance of the Mg-Ca alloy increased after coating with chitosan, and depended on both the chitosan molecular weight and layer numbers of coating. The Mg-Ca alloy coated by chitosan with a molecular weight of 2.7 x 10(5) for six layers has smooth and intact surface morphology, and exhibits the highest corrosion resistance in a simulated body fluid.

TiO2 nanofibers resembling 'yellow bristle grass' in morphology by a soft chemical transformation.

PubMed

Nandan, Sandeep; Deepak, T G; Nair, Shantikumar V; Nair, A Sreekumaran

2015-05-28

We synthesized a uniquely shaped one-dimensional (1-D) TiO2 nanostructure having the morphology of yellow bristle grass with high surface area by the titanate route under mild reaction conditions. The electrospun TiO2-SiO2 composite nanofibers upon treatment with concentrated NaOH at 80 °C under ambient pressure for 24 h resulted in sodium titanate (Na2Ti3O7) nanostructures. The Na2Ti3O7 nanostructures have an overall 1-D fibrous morphology but the highly porous fiber surfaces were decorated with layered thorn-like features (a morphology resembling that of yellow bristle grass) resulting in high surface area (113 m(2) g(-1)) and porosity. The Na2Ti3O7 nanostructures were converted into TiO2 nanostructures of the same morphology by acidification (0.1 N HCl) followed by low temperature sintering (110 °C) processes. Dye-sensitized solar cells (DSCs) constructed out of the material (cells of area 0.20 cm(2) and thickness 12 μm) showed a power conversion efficiency (η) of 8.02% in comparison with commercial P-25 TiO2 (η = 6.1%).

Quantitative Correlation of 7B04 Aluminum Alloys Pitting Corrosion Morphology Characteristics with Stress Concentration Factor

NASA Astrophysics Data System (ADS)

Liu, Zhiguo; Yan, Guangyao; Mu, Zhitao; Li, Xudong

2018-01-01

The accelerated pitting corrosion test of 7B04 aluminum alloy specimen was carried out according to the spectrum which simulated airport environment, and the corresponding pitting corrosion damage was obtained and was defined through three parameters A and B and C which respectively denoted the corrosion pit surface length and width and corrosion pit depth. The ratio between three parameters could determine the morphology characteristics of corrosion pits. On this basis the stress concentration factor of typical corrosion pit morphology under certain load conditions was quantitatively analyzed. The research shows that the corrosion pits gradually incline to be ellipse in surface and moderate in depth, and most value of B/A and C/A lies in 1 between 4 and few maximum exceeds 4; The stress concentration factor Kf of corrosion pits is obviously affected by the its morphology, the value of Kf increases with corrosion pits depth increasement under certain corrosion pits surface geometry. Also, the value of Kf decreases with surface width increasement under certain corrosion pits depth. The research conclusion can set theory basis for corrosion fatigue life analysis of aircraft aluminum alloy structure.

Texturing Carbon-carbon Composite Radiator Surfaces Utilizing Atomic Oxygen

NASA Technical Reports Server (NTRS)

Raack, Taylor

2004-01-01

Future space nuclear power systems will require radiator technology to dissipate excess heat created by a nuclear reactor. Large radiator fins with circulating coolant are in development for this purpose and an investigation of how to make them most efficient is underway. Maximizing the surface area while minimizing the mass of such radiator fins is critical for obtaining the highest efficiency in dissipating heat. Processes to develop surface roughness are under investigation to maximize the effective surface area of a radiator fin. Surface roughness is created through several methods including oxidation and texturing. The effects of atomic oxygen impingement on carbon-carbon surfaces are currently being investigated for texturing a radiator surface. Early studies of atomic oxygen impingement in low Earth orbit indicate significant texturing due to ram atomic oxygen. The surface morphology of the affected surfaces shows many microscopic cones and valleys which have been experimentally shown to increase radiation emittance. Further study of this morphology proceeded in the Long Duration Exposure Facility (LDEF). Atomic oxygen experiments on the LDEF successfully duplicated the results obtained from materials in spaceflight by subjecting samples to 4.5 eV atomic oxygen from a fixed ram angle. These experiments replicated the conical valley morphology that was seen on samples subjected to low Earth orbit.

Stem cell behavior on tailored porous oxide surface coatings.

PubMed

Lavenus, Sandrine; Poxson, David J; Ogievetsky, Nika; Dordick, Jonathan S; Siegel, Richard W

2015-07-01

Nanoscale surface topographies are known to have a profound influence on cell behavior, including cell guidance, migration, morphology, proliferation, and differentiation. In this study, we have observed the behavior of human mesenchymal stem cells cultured on a range of tailored porous SiO2 and TiO2 nanostructured surface coatings fabricated via glancing angle electron-beam deposition. By controlling the physical vapor deposition angle during fabrication, we could control systematically the deposited coating porosity, along with associated topographic features. Immunocytochemistry and image analysis quantitatively revealed the number of adherent cells, as well as their basic cellular morphology, on these surfaces. Signaling pathway studies showed that even with subtle changes in nanoscale surface structures, the behavior of mesenchymal stem cells was strongly influenced by the precise surface structures of these porous coatings. Copyright © 2015 Elsevier Ltd. All rights reserved.

Vertical self-sorting behavior in juvenile Chinook salmon (Oncorhynchus tshawytscha): evidence for family differences and variation in growth and morphology

USGS Publications Warehouse

Unrein, Julia R.; Billman, E.J.; Cogliati, Karen M.; Chitwood, Rob S.; Noakes, David L. G.; Schreck, Carl B.

2018-01-01

Life history variation is fundamental to the evolution of Pacific salmon and their persistence under variable conditions. We discovered that Chinook salmon sort themselves into surface- and bottom-oriented groups in tanks within days after exogenous feeding. We hypothesised that this behaviour is correlated with subsequent differences in body morphology and growth (as measured by final length and mass) observed later in life. We found consistent morphological differences between surface and bottom phenotypes. Furthermore, we found that surface and bottom orientation within each group is maintained for at least one year after the phenotypes were separated. These surface and bottom phenotypes are expressed across genetic stocks, brood years, and laboratories and we show that the proportion of surface- and bottom-oriented offspring also differed among families. Importantly, feed delivery location did not affect morphology or growth, and the surface fish were longer than bottom fish at the end of the rearing experiment. The body shape of the former correlates with wild individuals that rear in mainstem habitats and migrate in the fall as subyearlings and the latter resemble those that remain in the upper tributaries and migrate as yearling spring migrants. Our findings suggest that early self-sorting behaviour may have a genetic basis and be correlated with other phenotypic traits that are important indicators for juvenile migration timing.

A study of structural and mechanical properties of nano-crystalline tungsten nitride film synthesis by plasma focus

NASA Astrophysics Data System (ADS)

Hussnain, Ali; Singh Rawat, Rajdeep; Ahmad, Riaz; Hussain, Tousif; Umar, Z. A.; Ikhlaq, Uzma; Chen, Zhong; Shen, Lu

2015-02-01

Nano-crystalline tungsten nitride thin films are synthesized on AISI-304 steel at room temperature using Mather-type plasma focus system. The surface properties of the exposed substrate against different deposition shots are examined for crystal structure, surface morphology and mechanical properties using X-ray diffraction (XRD), atomic force microscope, field emission scanning electron microscope and nano-indenter. The XRD results show the growth of WN and WN2 phases and the development of strain/stress in the deposited films by varying the number of deposition shots. Morphology of deposited films shows the significant change in the surface structure with different ion energy doses (number of deposition shots). Due to the effect of different ion energy doses, the strain/stress developed in the deposited film leads to an improvement of hardness of deposited films.

Molecular dynamics simulation of potentiometric sensor response: the effect of biomolecules, surface morphology and surface charge.

PubMed

Lowe, B M; Skylaris, C-K; Green, N G; Shibuta, Y; Sakata, T

2018-05-10

The silica-water interface is critical to many modern technologies in chemical engineering and biosensing. One technology used commonly in biosensors, the potentiometric sensor, operates by measuring the changes in electric potential due to changes in the interfacial electric field. Predictive modelling of this response caused by surface binding of biomolecules remains highly challenging. In this work, through the most extensive molecular dynamics simulation of the silica-water interfacial potential and electric field to date, we report a novel prediction and explanation of the effects of nano-morphology on sensor response. Amorphous silica demonstrated a larger potentiometric response than an equivalent crystalline silica model due to increased sodium adsorption, in agreement with experiments showing improved sensor response with nano-texturing. We provide proof-of-concept that molecular dynamics can be used as a complementary tool for potentiometric biosensor response prediction. Effects that are conventionally neglected, such as surface morphology, water polarisation, biomolecule dynamics and finite-size effects, are explicitly modelled.

Coarse-grained molecular simulation of self-assembly for nonionic surfactants on graphene nanostructures.

PubMed

Wu, Dan; Yang, Xiaoning

2012-10-04

Self-assembly of amphiphilic molecules on the surfaces of nanoscale materials has an important application in a variety of nanotechnology. Here, we report a coarse-grained molecular dynamics simulation on the structure and morphology of the nonionic surfactant, n-alkyl poly(ethylene oxide) (PEO), adsorbed on planar graphene nanostructures. The effects of concentration, surfactant structure, and size of graphene sheet are explored. Because of the finite dimension effect, various morphological hemimicelles can be formed on nanoscale graphene surfaces, which is somewhat different from the self-assembly structures on infinite carbon surfaces. The aggregate morphology is highly dependent on the concentration, the chain lengths, and the size of graphene nanosheets. For the nonionic surfactant, the PEO headgroups show strong dispersion interaction with the carbon surface, leading to a side edge adsorption behavior. This simulation provides insight into the supramolecular self-assembly nanostructures and the adsorption mechanism for the nonionic surfactants aggregated on graphene nanostructures, which could be exploited to guide fabrication of graphene-based nanocomposites.

Impact of plasma treatment under atmospheric pressure on surface chemistry and surface morphology of extruded and injection-molded wood-polymer composites (WPC)

NASA Astrophysics Data System (ADS)

Hünnekens, Benedikt; Avramidis, Georg; Ohms, Gisela; Krause, Andreas; Viöl, Wolfgang; Militz, Holger

2018-05-01

The influence of plasma treatment performed at atmospheric pressure and ambient air as process gas by a dielectric barrier discharge (DBD) on the morphological and chemical surface characteristics of wood-polymer composites (WPC) was investigated by applying several surface-sensitive analytical methods. The surface free energy showed a distinct increase after plasma treatment for all tested materials. The analyzing methods for surface topography-laser scanning microscopy (LSM) and atomic force microscopy (AFM)-revealed a roughening induced by the treatment which is likely due to a degradation of the polymeric surface. This was accompanied by the formation of low-molecular-weight oxidized materials (LMWOMs), appearing as small globular structures. With increasing discharge time, the nodules increase in size and the material degradation proceeds. The surface degradation seems to be more serious for injection-molded samples, whereas the formation of nodules became more apparent and were evenly distributed on extruded surfaces. These phenomena could also be confirmed by scanning electron microscopy (SEM). In addition, differences between extruded and injection-molded surfaces could be observed. Besides the morphological changes, the chemical composition of the substrates' surfaces was affected by the plasma discharge. Infrared spectroscopy (ATR-FTIR) and X-ray photoelectron spectroscopy (XPS) indicated the formation of new oxygen containing polar groups on the modified surfaces.

Wear Behavior of Medium Carbon Steel with Biomimetic Surface Under Starved Lubricated Conditions

NASA Astrophysics Data System (ADS)

Zhang, Zhihui; Shao, Feixian; Liang, Yunhong; Lin, Pengyu; Tong, Xin; Ren, Luquan

2017-07-01

Friction and wear under starved lubrication condition are both key life-related factors for mechanical performance of many structural parts. In this paper, different surface morphologies on medium carbon steel were fabricated using laser, inspired by the surface coupling effect of biological system. The friction and sliding wear behaviors of biomimetic specimens (characterized by convex and concave units on the specimen surface) were studied under starved lubrication condition. The stress distribution on different sliding surfaces under sliding friction was studied using finite element method. The results showed that the tribological performance of studied surfaces under starved lubrication condition depended not only on the surface morphology but also on the structure of biomimetic units below surface (subsurface structure). The friction coefficient of biomimetic surface was effectively reduced by the concave unit depth, while the refined microstructure with higher hardness led to the much better wear resistance. In addition to lubricant reserving and wear debris trapping effect derived from the surface concave morphology, it was believed that the well-formed subsurface structure of biomimetic units could carry much heavy loads against tribopair, which enhanced the function of surface topography and resulted in complementary lubrication in the wear contact area. The uniform stress distribution on the entire biomimetic surface also played an important role in stabilizing the friction coefficient and reducing the wear cracks.

In-Vitro Comparative Study of In-office and Home Bleaching Agents on Surface Micro-morphology of Enamel.

PubMed

Fatima, Nazish

2016-01-01

To evaluate the effect of home-use bleaching agent containing 16% Carbamide Peroxide (CP) and in-office bleaching agent with 38% Hydrogen Peroxide (HP) on surface micro-morphology of enamel. An experimental study. The discs were prepared at Material Engineering Department of NED University of Engineering and Technology, Karachi, and surface morphology was analyzed at Centralized Science Laboratory of Karachi University, Pakistan. Duration of study was one year from January to December 2012. Forty five sound human third molar crowns, extracted for periodontal reason, were included in the study. Longitudinal sections were made using diamond disks (0.2 mm) under water lubrication to obtain enamel slabs measuring (3 mm x 3 mm). The slabs were embedded in polystyrene resin by using 2.0 cm diameter PVC molds, leaving the outer enamel surface uncovered by the resin. Ninety dental enamel slabs were prepared. The slabs were then randomly divided into 3 groups. Each group contained thirty specimens (n=30). Group 1 was kept in artificial saliva at 37°C in incubator (Memart, Germany) during whole experiment. Group 2 was treated with power whitening gel (White Smile 2011, Germany). Group 3 was treated with tooth whitening pen (White Smile 2011, Germany). The most central region or the region that was most representative of the entire surface area was used. The SEM (Jeol-Japan-JSM6380A, JAPAN) micrographs were examined to determine the type of surface presented. The enamel changes were classified as no or mild alteration, moderate alteration and severe altered surface. Regarding micro-morphology, the enamel surface of control groups showed smooth surface in general with some scattered clear scratches due to the polishing procedure. The specimens bleached in group 2 and group 3, represented areas of mild erosion. Bleaching with 38% Hydrogen Peroxide (HP) and 16% Carbamide Peroxide (CP) resulted in mild changes in surface micro-morphology of enamel.

Local-Scale Simulations of Nucleate Boiling on Micrometer Featured Surfaces: Preprint

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

Sitaraman, Hariswaran; Moreno, Gilberto; Narumanchi, Sreekant V

2017-08-03

A high-fidelity computational fluid dynamics (CFD)-based model for bubble nucleation of the refrigerant HFE7100 on micrometer-featured surfaces is presented in this work. The single-fluid incompressible Navier-Stokes equations, along with energy transport and natural convection effects are solved on a featured surface resolved grid. An a priori cavity detection method is employed to convert raw profilometer data of a surface into well-defined cavities. The cavity information and surface morphology are represented in the CFD model by geometric mesh deformations. Surface morphology is observed to initiate buoyancy-driven convection in the liquid phase, which in turn results in faster nucleation of cavities. Simulationsmore » pertaining to a generic rough surface show a trend where smaller size cavities nucleate with higher wall superheat. This local-scale model will serve as a self-consistent connection to larger device scale continuum models where local feature representation is not possible.« less

Local-Scale Simulations of Nucleate Boiling on Micrometer-Featured Surfaces

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

Sitaraman, Hariswaran; Moreno, Gilberto; Narumanchi, Sreekant V

2017-07-12

A high-fidelity computational fluid dynamics (CFD)-based model for bubble nucleation of the refrigerant HFE7100 on micrometer-featured surfaces is presented in this work. The single-fluid incompressible Navier-Stokes equations, along with energy transport and natural convection effects are solved on a featured surface resolved grid. An a priori cavity detection method is employed to convert raw profilometer data of a surface into well-defined cavities. The cavity information and surface morphology are represented in the CFD model by geometric mesh deformations. Surface morphology is observed to initiate buoyancy-driven convection in the liquid phase, which in turn results in faster nucleation of cavities. Simulationsmore » pertaining to a generic rough surface show a trend where smaller size cavities nucleate with higher wall superheat. This local-scale model will serve as a self-consistent connection to larger device scale continuum models where local feature representation is not possible.« less

Carbon decorative coatings by dip-, spin-, and spray-assisted layer-by-layer assembly deposition.

PubMed

Hong, Jinkee; Kang, Sang Wook

2011-09-01

We performed a comparative surface analysis of all-carbon nano-objects (multiwall carbon nanotubes (MWNT) or graphene oxide (GO) sheets) based multilayer coatings prepared using three widely used nanofilm fabrication methods: dip-, spin-, and spray-assisted layer-by-layer (LbL) deposition. The resultant films showed a marked difference in their growth mechanisms and surface morphologies. Various carbon decorative coatings were synthesized with different surface roughness values, despite identical preparation conditions. In particular, smooth to highly rough all-carbon surfaces, as determined by atomic force microscopy (AFM) and scanning electron microscopy (SEM), were readily obtained by manipulating the LbL deposition methods. As was confirmed by the AFM and SEM analyses, this finding indicated the fundamental morphological evolution of one-dimensional nano-objects (MWNT) and two-dimensional nano-objects (GO) by control of the surface roughness through the deposition method. Therefore, an analysis of the three LbL-assembly methods presented herein may offer useful information about the industrial use of carbon decorative coatings and provide an insight into ways to control the structures of multilayer coatings by tuning the morphologies of carbon nano-objects.

Chip morphology as a performance predictor during high speed end milling of soda lime glass

NASA Astrophysics Data System (ADS)

Bagum, M. N.; Konneh, M.; Abdullah, K. A.; Ali, M. Y.

2018-01-01

Soda lime glass has application in DNA arrays and lab on chip manufacturing. Although investigation revealed that machining of such brittle material is possible using ductile mode under controlled cutting parameters and tool geometry, it remains a challenging task. Furthermore, ability of ductile machining is usually assed through machined surface texture examination. Soda lime glass is a strain rate and temperature sensitive material. Hence, influence on attainment of ductile surface due to adiabatic heat generated during high speed end milling using uncoated tungsten carbide tool is investigated in this research. Experimental runs were designed using central composite design (CCD), taking spindle speed, feed rate and depth of cut as input variable and tool-chip contact point temperature (Ttc) and the surface roughness (Rt) as responses. Along with machined surface texture, Rt and chip morphology was examined to assess machinability of soda lime glass. The relation between Ttc and chip morphology was examined. Investigation showed that around glass transition temperature (Tg) ductile chip produced and subsequently clean and ductile final machined surface produced.

Linking morphology with activity through the lifetime of pretreated PtNi nanostructured thin film catalysts

DOE PAGES

Cullen, David A.; Lopez-Haro, Miguel; Bayle-Guillemaud, Pascale; ...

2015-04-10

In this study, the nanoscale morphology of highly active Pt 3Ni 7 nanostructured thin film fuel cell catalysts is linked with catalyst surface area and activity following catalyst pretreatments, conditioning and potential cycling. The significant role of fuel cell conditioning on the structure and composition of these extended surface catalysts is demonstrated by high resolution imaging, elemental mapping and tomography. The dissolution of Ni during fuel cell conditioning leads to highly complex, porous structures which were visualized in 3D by electron tomography. Quantification of the rendered surfaces following catalyst pretreatment, conditioning, and cycling shows the important role pore structure playsmore » in surface area, activity, and durability.« less

Growth and modelling of spherical crystalline morphologies of molecular materials

NASA Astrophysics Data System (ADS)

Shalev, O.; Biswas, S.; Yang, Y.; Eddir, T.; Lu, W.; Clarke, R.; Shtein, M.

2014-10-01

Crystalline, yet smooth, sphere-like morphologies of small molecular compounds are desirable in a wide range of applications but are very challenging to obtain using common growth techniques, where either amorphous films or faceted crystallites are the norm. Here we show solvent-free, guard flow-assisted organic vapour jet printing of non-faceted, crystalline microspheroids of archetypal small molecular materials used in organic electronic applications. We demonstrate how process parameters control the size distribution of the spheroids and propose an analytical model and a phase diagram predicting the surface morphology evolution of different molecules based on processing conditions, coupled with the thermophysical and mechanical properties of the molecules. This experimental approach opens a path for exciting applications of small molecular organic compounds in optical coatings, textured surfaces with controlled wettability, pharmaceutical and food substance printing and others, where thick organic films and particles with high surface area are needed.

Spine micromorphology of normal and hyperhydric Mammillaria gracilis Pfeiff. (Cactaceae) shoots.

PubMed

Peharec, P; Posilović, H; Balen, B; Krsnik-Rasol, M

2010-07-01

Artificial conditions of tissue culture affect growth and physiology of crassulacean acid metabolism plants which often results in formation of hyperhydric shoots. In in vitro conditions Mammillaria gracilis Pfeiff. (Cactaceae) growth switches from organized to unorganized way, producing a habituated organogenic callus which simultaneously regenerates morphologically normal as well as altered hyperhydric shoots. In this study, influence of tissue culture conditions on morphology of cactus spines of normal and hyperhydric shoots was investigated. Spines of pot-grown Mammillaria plants and of in vitro regenerated shoots were examined with stereo microscope and scanning electron microscope. The pot-grown plants had 16-17 spines per areole. In vitro grown normal shoots, even though they kept typical shoot morphology, had lower number of spines (11-12) and altered spine morphology. This difference was even more pronounced in spine number (six to seven) and morphology of the hyperhydric shoots. Scanning electron microscopy analysis revealed remarkable differences in micromorphology of spine surface between pot-grown and in vitro grown shoots. Spines of in vitro grown normal shoots showed numerous long trichomes, which were more elongated on spines of the hyperhydric shoots; the corresponding structures on spine surface of pot-grown plants were noticed only as small protrusions. Scanning electron microscopy morphometric studies showed that the spines of pot-grown plants were significantly longer compared to the spines of shoots grown in tissue culture. Moreover, transverse section shape varies from elliptical in pot-grown plants to circular in normal and hyperhydric shoots grown in vitro. Cluster and correspondence analyses performed on the scanning electron microscope obtained results suggest great variability among spines of pot-grown plants. Spines of in vitro grown normal and hyperhydric shoots showed low level of morphological variation among themselves despite the significant difference in shoot morphology.

Optimization of surface morphology and scattering properties of TCO/AIT textured glass front electrode for thin film solar cells

NASA Astrophysics Data System (ADS)

Addonizio, M. L.; Fusco, L.; Antonaia, A.; Cominale, F.; Usatii, I.

2015-12-01

Aluminium induced texture (AIT) method has been used for obtaining highly textured glass substrate suitable for silicon based thin film solar cell technology. Wet etch step parameters of AIT process have been varied and effect of different etchants and different etching times on morphological and optical properties has been analyzed. The resulting morphology features (shape, size distribution, inclination angle) have been optimized in order to obtain the best scattering properties. ZnO:Ga (GZO) films have been deposited by sputtering technique on AIT-processed glass. Two different ZnO surface morphologies have been obtained, strongly depending on the underlying glass substrate morphology induced by different etching times. Very rough and porous texture (σrms ∼ 150 nm) was obtained on glass etched 2 min showing cauliflower-like structure, whereas a softer texture (σrms ∼ 78 nm) was obtained on glass etched 7 min giving wider and smoother U-shaped craters. The effect of different glass textures on optical confinement has been tested in amorphous silicon based p-i-n devices. Devices fabricated on GZO/high textured glass showed a quantum efficiency enhancement due to both an effective light trapping phenomenon and an effective anti-reflective optical behaviour. Short etching time produce smaller cavities (<1 μm) with deep U-shape characterized by high roughness, high inclination angle and low autocorrelation length. This surface morphology promoted a large light scattering phenomenon, as evidenced by haze value and by angular resolved scattering (ARS) behaviour, into a large range of diffraction angles, giving high probability of effective light trapping inside a PV device.

Graphene as a Coating for Plasma Facing Components

NASA Astrophysics Data System (ADS)

Navarro, Marcos; Zamiri, Marziyeh; Kulcinski, Gerald; Lagally, Max; Santarius, John

2017-10-01

This research explores the protection by graphene of plasma facing materials bombarded with energetic ions of helium. Few studies have shown that graphene can act as a protective layer against sputtering due to energetic ions. In the presence of such irradiation, plasma facing components (PFC's) tend to develop surface morphologies that lead to the sputtering of wall material, potentially diminishing the lifetime of the PFC's and plasma performance. Since plasmas have broad applications and the quality of transferred and grown graphene is different, we have used a chemical vapor deposition method to grow on other substrates. We have also shown that graphene can reduce changes on surface morphology due to energetic helium. After irradiation, in the case of graphene-covered tungsten, our results show that, compared to the uncovered W, graphene suppresses these morphologies that form on the surface of hot W. Using Raman spectroscopy as a diagnostic, the graphene coating shows little sign of damage after being irradiated, indicating that there is little to no sputtering of carbon impurities from the surface. We have determined that the mass losses in W have been reduced significantly, which may lead to an improved plasma performance and longer PFC lifetimes. Supported by DHS Project 2015-DN-077-ARI095 and the Grainger Foundation.

Effects of hydrogen peroxide on the light reflectance and morphology of bovine enamel.

PubMed

Kwon, Y H; Huo, M S; Kim, K H; Kim, S K; Kim, Y J

2002-05-01

The purpose of this study was to examine the effects of a bleaching agent (30% hydrogen peroxide) on the surface of bovine enamel using a scanning electron microscope and a UV-VIS-NIR spectrophotometer. Five non-carious bovine incisors were bleached for 0, 1, 2 and 3 days using 30% hydrogen peroxide. The light reflectance spectrum was measured using a spectrophotometer with diffuse reflectance mode. Colour values and colour differences in the teeth were evaluated from the reflectance measurements with the CIE L*a*b* colour coordinate system. Surface alterations in the bleached and unbleached teeth were studied using a scanning electron microscope. The change of reflectance in the teeth was related to the change of colour. Most reflectance change occurred within a 1-day bleaching, and this result was confirmed by a CIE L*a*b* colour coordinate system. The colour differences in the bleached teeth were significant enough to be perceived by the observer's eye. The comparison of bleached to unbleached bovine enamel revealed that the bleached surface showed non-uniform slight morphological alterations, and it developed varying degrees of surface porosity. This study indicates that the bleached bovine teeth showed apparent colour differences as well as slight morphological alterations after bleaching.

Bi-stage time evolution of nano-morphology on inductively coupled plasma etched fused silica surface caused by surface morphological transformation

NASA Astrophysics Data System (ADS)

Jiang, Xiaolong; Zhang, Lijuan; Bai, Yang; Liu, Ying; Liu, Zhengkun; Qiu, Keqiang; Liao, Wei; Zhang, Chuanchao; Yang, Ke; Chen, Jing; Jiang, Yilan; Yuan, Xiaodong

2017-07-01

In this work, we experimentally investigate the surface nano-roughness during the inductively coupled plasma etching of fused silica, and discover a novel bi-stage time evolution of surface nano-morphology. At the beginning, the rms roughness, correlation length and nano-mound dimensions increase linearly and rapidly with etching time. At the second stage, the roughening process slows down dramatically. The switch of evolution stage synchronizes with the morphological change from dual-scale roughness comprising long wavelength underlying surface and superimposed nano-mounds to one scale of nano-mounds. A theoretical model based on surface morphological change is proposed. The key idea is that at the beginning, etched surface is dual-scale, and both larger deposition rate of etch inhibitors and better plasma etching resistance at the surface peaks than surface valleys contribute to the roughness development. After surface morphology transforming into one-scale, the difference of plasma resistance between surface peaks and valleys vanishes, thus the roughening process slows down.

Effects of Laser Shock Processing on Morphologies and Mechanical Properties of ANSI 304 Stainless Steel Weldments Subjected to Cavitation Erosion

PubMed Central

Zhang, Lei; Lu, Jin-Zhong; Zhang, Yong-Kang; Ma, Hai-Le; Luo, Kai-Yu; Dai, Feng-Ze

2017-01-01

Effects of laser shock processing (LSP) on the cavitation erosion resistance of laser weldments were investigated by optical microscope (OM), scanning electron microscope (SEM) observations, roughness tester, micro hardness tester, and X-ray diffraction (XRD) technology. The morphological microstructures were characterized. Cumulative mass loss, incubation period, erosion rate, and damaged surface areas were monitored during cavitation erosion. Surface roughness, micro-hardness, and residual stress were measured in different zones. Results showed that LSP could improve the damage of morphological microstructures and mechanical properties after cavitation erosion. The compressive residual stresses were generated during the process of LSP, which was an effective guarantee for the improvement of the above mentioned properties. PMID:28772652

Surface alloying in Sn/Au(111) at elevated temperature

NASA Astrophysics Data System (ADS)

Sadhukhan, Pampa; Singh, Vipin Kumar; Rai, Abhishek; Bhattacharya, Kuntala; Barman, Sudipta Roy

2018-04-01

On the basis of x-ray photoelectron spectroscopy, we show that when Sn is deposited on Au(111) single crystal surface at a substrate temperature TS=373 K, surface alloying occurs with the formation of AuSn phase. The evolution of the surface structure and the surface morphology has been studied by low energy electron diffraction and scanning tunneling microscopy, respectively as a function of Sn coverage and substrate temperatures.

Evaluation of enamel by scanning electron microscopy green LED associated to hydrogen peroxide 35% for dental bleaching

NASA Astrophysics Data System (ADS)

Monteiro, Juliana S. C.; de Oliveira, Susana C. P. S.; Zanin, Fátima A. A.; Santos, Gustavo M. P.; Sampaio, Fernando J. P.; Gomes Júnior, Rafael Araújo; Gesteira, Maria F. M.; Vannier-Santos, Marcos A.; Pinheiro, Antônio Luiz B.

2014-02-01

Dental bleaching is a frequently requested procedure in clinical dental practice. The literature is contradictory regarding the effects of bleaching agents on both morphology and demineralization of enamel after bleaching. The aim of this study was to analyze by SEM the effect of 35% neutral hydrogen peroxide cured by green LED. Buccal surfaces of 15 pre-molars were sectioned and marked with a central groove to allow experimental and control groups on the same specimen. For SEM, 75 electron micrographs were evaluated by tree observers at 43X, 220X and 1000X. Quantitative analysis for the determination of the surface elemental composition of the samples through X-ray microanalysis by SEM was also performed. The protocol tested neither showed significant changes in mineral composition of the samples nor to dental enamel structure when compared to controls. SEM analysis allowed inferring that there were marked morphological differences between the enamel samples highlighting the need for the use of the same tooth in comparative morphological studies. The tested protocol did not cause morphological damage the enamel surface when compared to their respective controls.

ZnO nanostructures with different morphology for enhanced photocatalytic activity

NASA Astrophysics Data System (ADS)

Peter, I. John; Praveen, E.; Vignesh, G.; Nithiananthi, P.

2017-12-01

ZnO nanomaterials of different morphologies have been synthesized and the effect of morphology on Photocatalytic activity on natural dye has been investigated. Crystalline size and lattice strain of the synthesized particles are determined by XRD analysis and Williamson-Hall (W-H) method respectively. All other important physical parameters such as strain, stress and energy density values are also calculated using W-H analysis using different models such as uniform deformation model, uniform deformation stress model and uniform deformation energy density model. A shift in the peak of FTIR spectrum of ZnO is observed due to morphology effects. The SEM analysis reveals that the synthesized ZnO nanoparticles appear as flake, rod and dot. ZnO quantum dot exhibits higher photocatalytic activity comparing to the other morphologies. Larger surface area, high adsorption rate, large charge separation and the slow recombination of electrons/holes in ZnO dots establish dots as favorable morphology for good photocatalysis. Among the three, ZnO quantum dot shows three-times enhancement in the kinetic rate constants of photocatalysis. The results confirm that availability of specific (active) surface area, photocatalytic potential and quantum confinement of photo-induced carriers differ with morphology.

Characteristics of hierarchical micro/nano surface structure formation generated by picosecond laser processing in water and air

NASA Astrophysics Data System (ADS)

Rajab, Fatema H.; Whitehead, David; Liu, Zhu; Li, Lin

2017-12-01

Laser surface texturing or micro/nano surface structuring in the air has been extensively studied. However, until now, there are very few studies on the characteristics of laser-textured surfaces in water, and there was no reported work on picosecond laser surface micro/nano-structuring in water. In this work, the surface properties of picosecond laser surface texturing in water and air were analysed and compared. 316L stainless steel substrates were textured using a picosecond laser. The surface morphology and the chemical composition were characterised using Philips XL30 FEG-SEM, EDX and confocal laser microscopy. The wettability of the textured surfaces was determined using a contact angle analyser FTA 188. Results showed that a variety of hierarchical micro/nano surface patterns could be controlled by a suitable adjustment of laser parameters. Not only surface morphology but also remarkable differences in wettability, optical reflectivity and surface oxygen content were observed for different types of surface textures produced by laser surface texture in water and air. The possible mechanisms of the changes in the behaviour of laser-textured surfaces are discussed.

Degradation of blue and red inks by Ag/AgCl photocatalyst under UV light irradiation

NASA Astrophysics Data System (ADS)

Daupor, Hasan; Chenea, Asmat

2017-08-01

Objective of this research, cubic Ag/AgCl photocatalysts with an average particle size of 500 nm has been successfully synthesized via a modified precipitation reaction between ZrCl4 and AgNO3. Method for analysis, the crystal structure of the product was characterized by X-ray powder diffraction (XRD). The morphology and composition were studied by scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), UV-vis diffuse-reflection spectra (DRS) and so on. The result showed that the optical absorption spectrum exhibited strong absorption in the visible region around 500-600 nm due to surface plasmon resonance (SPR) of metallic silver nanoparticles. SEM micrographs showed that the obtained Ag/AgCl had cubic morphology and appeared on the porous surface as the cubic cage morphology. As a result, this porous surface also positively affected the photocatalytic reaction. The photocatalytic activity of the obtained product was evaluated by the photodegradation of blue and red ink solutions under UV light irradiation, and it was interestingly, discovered that AgCl could degrade 0.25% and 0.10% in 7 hours for blue and red inks solution respectively, Which were higher than of commercial AgCl. The result suggested that the morphology of Ag/AgCl strongly affected their photocatalytic activities. O2-, OH- reaction. radicals and Cl° atom are main species during photocatalytic reaction.

Emphasizing the role of surface chemistry on hydrophobicity and cell adhesion behavior of polydimethylsiloxane/TiO2 nanocomposite films.

PubMed

Yousefi, Seyedeh Zahra; Tabatabaei-Panah, Pardis-Sadat; Seyfi, Javad

2018-07-01

Improving the bioinertness of materials is of great importance for developing biomedical devices that contact human tissues. The main goal of this study was to establish correlations among surface morphology, roughness and chemistry with hydrophobicity and cell adhesion in polydimethylsiloxane (PDMS) nanocomposites loaded with titanium dioxide (TiO 2 ) nanoparticles. Firstly, wettability results showed that the nanocomposite loaded with 30 wt.% of TiO 2 exhibited a superhydrophobic behavior; however, the morphology and roughness analysis proved that there was no discernible difference between the surface structures of samples loaded with 20 and 30 wt.% of nanoparticles. Both cell culture and MTT assay experiments showed that, despite the similarity between the surface structures, the sample loaded with 30 wt.% nanoparticles exhibits the greatest reduction in the cell viability (80%) as compared with the pure PDMS film. According to the X-ray photoelectron spectroscopy results, the remarkable reduction in cell viability of the superhydrophobic sample could be majorly attributed to the role of surface chemistry. The obtained results emphasize the importance of adjusting the surface properties especially surface chemistry to gain the optimum cell adhesion behavior. Copyright © 2018 Elsevier B.V. All rights reserved.

Exploring Statistical Characterizations of Morphologic Change and Variability: Fire Island, New York

NASA Astrophysics Data System (ADS)

Lentz, E. E.; Hapke, C. J.

2012-12-01

A comprehensive understanding of coastal barrier behavior requires high-resolution observations that capture a wide range of morphological changes occurring over a range of spatial and temporal scales. Fire Island National Seashore, located along the coast of Long Island, New York, is a well studied barrier island coast where understanding how morphological changes contribute to barrier island vulnerability have important implications for coastal land management. Previous work has shown that morphologic differences in eastern and western reaches are attributable to the underlying geology and variations sediment transport in the system. In this study, we further explore western and eastern differences and variability with lidar-derived topographic surfaces to provide a unique and comprehensive investigation of dune-beach change at Fire Island, New York. Continuous topographic surfaces generated from 12 lidar surveys collected between 1998 and 2011 are used to examine the three-dimensional variability over a range of time periods over the 50 km long island. Because surveys were collected over a range of seasons and in response to a number of storm events, we explore morphologic configurations reflecting the seasonality, post-storm configuration, and replenishment response to the system through the generation of a representative or average surface. These averaged surfaces provide the context for what would be an expected or typical coastal configuration under certain conditions, and through comparison with an individual event, can be used to derive an event-specific spatial-change signature. To investigate anthropogenic influences, differences in morphology between a survey collected after a substantial beach replenishment project and a typical fair-weather configuration averaged from six surveys are determined. Storm response variations are also explored by assessing differences between Tropical Storm Irene (2011), Nor'Ida (2009), and a typical post-storm configuration averaged from five post-storm surveys. In addition to averaged surfaces, surveys are combined to generate a new raster surface reflecting cell by cell standard deviations over a defined period. Standard deviation surfaces are generated to highlight 1) where areas of highest and lowest morphologic variation are located over the entire period, and 2) whether spatial similarities exist in variability between storm and non-storm morphologies. Results show there are distinct and variable responses in eastern and western reaches attributable to wave climate, profile gradient, and offshore bathymetry, as well as to a general along-coast increase in sediment availability.

On the influence of substrate morphology and surface area on phytofauna

USGS Publications Warehouse

Becerra-Munoz, S.; Schramm, H.L.

2007-01-01

The independent effects and interactions between substrate morphology and substrate surface area on invertebrate density or biomass colonizing artificial plant beds were assessed in a clear-water and a turbid playa lake in Castro County, Texas, USA. Total invertebrate density and biomass were consistently greater on filiform substrates than on laminar substrates with equivalent substrate surface areas. The relationship among treatments (substrates with different morphologies and surface areas) and response (invertebrate density or biomass) was assessed with equally spaced surface areas. Few statistically significant interactions between substrate morphology and surface area were detected, indicating that these factors were mostly independent from each other in their effect on colonizing invertebrates. Although infrequently, when substrate morphology and surface area were not independent, the effects of equally spaced changes in substrate surface area on the rate of change of phytofauna density or biomass per unit of substrate surface area were dependent upon substrate morphology. The absence of three-way interactions indicated that effects of substrate morphology and substrate area on phytofauna density or biomass were independent of environmental conditions outside and inside exclosures. ?? 2006 Springer Science+Business Media B.V.

Nano hydroxyapatite-blasted titanium surface affects pre-osteoblast morphology by modulating critical intracellular pathways.

PubMed

Bezerra, Fábio; Ferreira, Marcel R; Fontes, Giselle N; da Costa Fernandes, Célio Jr; Andia, Denise C; Cruz, Nilson C; da Silva, Rodrigo A; Zambuzzi, Willian F

2017-08-01

Although, intracellular signaling pathways are proposed to predict the quality of cell-surface relationship, this study addressed pre-osteoblast behavior in response to nano hydroxyapatite (HA)-blasted titanium (Ti) surface by exploring critical intracellular pathways and pre-osteoblast morphological change. Physicochemical properties were evaluated by atomic force microscopy (AFM) and wettability considering water contact angle of three differently texturized Ti surfaces: Machined (Mac), Dual acid-etching (DAE), and nano hydroxyapatite-blasted (nHA). The results revealed critical differences in surface topography, impacting the water contact angle and later the osteoblast performance. In order to evaluate the effect of those topographical characteristics on biological responses, we have seeded pre-osteoblast cells on the Ti discs for up to 4 h and subjected the cultures to biological analysis. First, we have observed pre-osteoblasts morphological changes resulting from the interaction with the Ti texturized surfaces whereas the cells cultured on nHA presented a more advanced spreading process when compared with the cells cultured on the other surfaces. These results argued us for analyzing the molecular machinery and thus, we have shown that nHA promoted a lower Bax/Bcl2 ratio, suggesting an interesting anti-apoptotic effect, maybe explained by the fact that HA is a natural element present in bone composition. Thereafter, we investigated the potential effect of those surfaces on promoting pre-osteoblast adhesion and survival signaling by performing crystal violet and immunoblotting approaches, respectively. Our results showed that nHA promoted a higher pre-osteoblast adhesion supported by up-modulating FAK and Src activations, both signaling transducers involved during eukaryotic cell adhesion. Also, we have shown Ras-Erk stimulation by the all evaluated surfaces. Finally, we showed that all Ti-texturing surfaces were able to promote osteoblast differentiation up to 10 days, when alkaline phosphatase (ALP) activity and osteogenic transcription factors were up-modulated. Altogether, our results showed for the first time that nano hydroxyapatite-blasted titanium surface promotes crucial intracellular signaling network responsible for cell adapting on the Ti-surface.Biotechnol. Bioeng. 2017;114: 1888-1898. © 2017 Wiley Periodicals, Inc. © 2017 Wiley Periodicals, Inc.

Au-nanoparticles grafted on plasma treated PE

NASA Astrophysics Data System (ADS)

Švorčík, V.; Chaloupka, A.; Řezanka, P.; Slepička, P.; Kolská, Z.; Kasálková, N.; Hubáček, T.; Siegel, J.

2010-03-01

Polyethylene (PE) surface was treated with Ar plasma. Activated surface was grafted from methanol solution of 1,2-ethanedithiol. Then the sample was immersed into freshly prepared colloid solution of Au-nanoparticles. Finally Au layer was sputtered on the samples. Properties of the modified PE were studied using various methods: AFM, EPR, RBS and nanoindentation. It was shown that the plasma treatment results in degradation of polymer chain (AFM) and creation of free radicals by EPR. After grafting with dithiol, the concentration of free radicals declines. The presence of Au and S in the surface layer after the coating with Au-nanoparticles was proved by RBS. Plasma treatment changes PE surface morphology and increases surface roughness, too. Another significant change in surface morphology and roughness was observed after deposition of Au-nanoparticles. Nanoindentation measurements show that the grafting with Au-nanoparticles increases adhesion of subsequently sputtered Au layer.

Nanoscale analysis of the morphology and surface stability of calcium carbonate polymorphs

PubMed Central

Sekkal, W.; Zaoui, A.

2013-01-01

Under earth surface conditions, in ocean and natural water, calcium carbonate is ubiquitous, forming anhydrous and hydrous minerals. These hydrous phases are of considerable interest for their role as precursors to stable carbonate minerals. Atomistic simulation techniques have been employed here to perform a comprehensive and quantitative study of the structural and energetic stability of dry and hydrous surfaces of calcium carbonate polymorphs using two recently developed forcefields. Results show that the dry forms are prone to ductility; while hydrous phases are found to be brittle. The (001) surface of monohydrocalcite appears to be the most stable (0.99 J/m2) whereas for the ikaite phase, the (001) surface is the most stable. The corresponding value is 0.2 J/m2, i.e. even lower than the surface energy of the Beautiful computed morphology pictures are obtained with Xiao's model and are very similar to the observed SEM images. PMID:23545842

Nanoscale analysis of the morphology and surface stability of calcium carbonate polymorphs.

PubMed

Sekkal, W; Zaoui, A

2013-01-01

Under earth surface conditions, in ocean and natural water, calcium carbonate is ubiquitous, forming anhydrous and hydrous minerals. These hydrous phases are of considerable interest for their role as precursors to stable carbonate minerals. Atomistic simulation techniques have been employed here to perform a comprehensive and quantitative study of the structural and energetic stability of dry and hydrous surfaces of calcium carbonate polymorphs using two recently developed forcefields. Results show that the dry forms are prone to ductility; while hydrous phases are found to be brittle. The (001) surface of monohydrocalcite appears to be the most stable (0.99 J/m(2)) whereas for the ikaite phase, the (001) surface is the most stable. The corresponding value is 0.2 J/m(2), i.e. even lower than the surface energy of the Beautiful computed morphology pictures are obtained with Xiao's model and are very similar to the observed SEM images.

Nanoscale analysis of the morphology and surface stability of calcium carbonate polymorphs

NASA Astrophysics Data System (ADS)

Sekkal, W.; Zaoui, A.

2013-04-01

Under earth surface conditions, in ocean and natural water, calcium carbonate is ubiquitous, forming anhydrous and hydrous minerals. These hydrous phases are of considerable interest for their role as precursors to stable carbonate minerals. Atomistic simulation techniques have been employed here to perform a comprehensive and quantitative study of the structural and energetic stability of dry and hydrous surfaces of calcium carbonate polymorphs using two recently developed forcefields. Results show that the dry forms are prone to ductility; while hydrous phases are found to be brittle. The (001) surface of monohydrocalcite appears to be the most stable (0.99 J/m2) whereas for the ikaite phase, the (001) surface is the most stable. The corresponding value is 0.2 J/m2, i.e. even lower than the surface energy of the Beautiful computed morphology pictures are obtained with Xiao's model and are very similar to the observed SEM images.

Experimental and FDTD study of silicon surface morphology induced by femtosecond laser irradiation at a high substrate temperature.

PubMed

Deng, Guoliang; Feng, Guoying; Zhou, Shouhuan

2017-04-03

Substrate temperature is an important parameter for controlling the properties of femtosecond laser induced surface structures besides traditional ways. The morphology on silicon surface at different temperatures are studied experimentally. Compared to those formed at 300 K, smoother ripples, micro-grooves and nano/micro-holes are formed at 700 K. A two temperature model and FDTD method are used to discuss the temperature dependence of surface structures. The results show that the increased light absorption at elevated temperature leads to the reduction of surface roughness. The type-g feature in the FDTD-η map at 700 K, which corresponds to the energy deposition modulation parallel to the laser polarization with a periodicity bigger than the wavelength, is the origin of the formation of grooves. This work can benefit both surface structures based applications and the study of femtosecond laser-matter interactions.

Structural, morphological and optical studies of F doped SnO2 thin films

NASA Astrophysics Data System (ADS)

Chandel, Tarun; Thakur, Vikas; Dwivedi, Shailendra Kumar; Zaman, M. Burhanuz; Rajaram, Poolla

2018-05-01

Highly conducting and transparent FTO (flourine doped tin Oxide) thin films were grown on the glass substrates using a low cost spray pyrolysis technique. The films were characterized for their structural, morphological and optical studies using XRD, SEM and UV-Vis spectroscopy. XRD studies show that the FTO films crystallize in Tetragonal cassiterite structure. Morphological analysis using SEM show that the films are uniformly covered with spherical grains albeit high in surface roughness. The average optical transmission greater than 80% in the visible region along with the appearance of interference fringes in the transmission curves confirms the high quality of the films. Electrical studies show that the films exhibit sheet resistance below 10 Ω ϒ-1.

Effect of laser irradiation on surface hardness and structural parameters of 7178 aluminium alloy

NASA Astrophysics Data System (ADS)

Maryam, Siddra; Bashir, Farooq

2018-04-01

Aluminium 7178 samples were prepared and irradiated with Nd:YAG laser. The surfaces of exposed samples were investigated using optical microscopy, which revealed that the surface morphology of the samples is changed drastically as a function of laser shots. It is revealed from the micrographs that the laser heat effected area increases with the increase in the number of the laser pulses. Furthermore morphological and mechanical properties were studied using XRD and Vickers hardness testing. XRD study shows an increasing trend in Grain size with the increasing number of laser shots. And the hardness of the samples as a function of the laser shots shows that the hardness first increases and then it decreases gradually. It was observed that the grain size has no pronouncing effect on the hardness. Hardness profile has a decreasing trend with the increase in linear distance from the boundary of the laser heat affected area.

Correlation between morphology, electron band structure, and resistivity of Pb atomic chains on the Si(5 5 3)-Au surface

NASA Astrophysics Data System (ADS)

Jałochowski, M.; Kwapiński, T.; Łukasik, P.; Nita, P.; Kopciuszyński, M.

2016-07-01

Structural and electron transport properties of multiple Pb atomic chains fabricated on the Si(5 5 3)-Au surface are investigated using scanning tunneling spectroscopy, reflection high electron energy diffraction, angular resolved photoemission electron spectroscopy and in situ electrical resistance. The study shows that Pb atomic chains growth modulates the electron band structure of pristine Si(5 5 3)-Au surface and hence changes its sheet resistivity. Strong correlation between chains morphology, electron band structure and electron transport properties is found. To explain experimental findings a theoretical tight-binding model of multiple atomic chains interacting on effective substrate is proposed.

Influence of low concentration acid treatment on lithium disilicate core/veneer ceramic bond strength

PubMed Central

Garcia, Rudan P.; Conti, Paulo CR.; Pereira, Jefferson R.; Valle, Accácio Ld.

2013-01-01

Objective: This study evaluated the influence of low concentration acid treatment on the shear bond strength between lithium disilicate (LD) infrastructure and veneering porcelain. The surface morphology characteristic after this acid treatment was also examined. Study Design: LD reinforced ceramic cylinders (n=10) (IPS e.max Press, Ivoclar-Vivadent, Schaan, Liechtenstein) were treated (LD-treated) with a low concentration acid solution (Invex Liquid – Ivoclar-Vivadent, Schaan, Liechtenstein) or not treated with the acid solution (LD-untreated). They were veneered with a glass ceramic (IPS e.max Ceram, Ivoclar-Vivadent, Schaan, Liechtenstein). A metal ceramic group (CoCr) was tested as control. Shear bond strength (SBS) was conducted using a universal testing machine at 0.5 mm/min. Surface morphology characteristics after acid treatment were analyzed using scanning electron microscopy. Results: The acid treatment at low concentrations did not influence the SBS of the LD/veneering porcelain interface. The CoCr group showed the significant higher SBS value (35.59 ± 5.97 MPa), followed by LD-untreated group (27.76 ± 3.59 MPa) and LD-treated (27.02 ± 4.79 MPa). The fracture modes were predominantly adhesive for CoCr group and cohesive within the infrastructure for DL groups. Scanning Electron Microscopy (SEM) analysis showed no morphological differences between treated and untreated LD surfaces. Conclusions: Low concentration acid treatment did not improved SBS of veneering ceramic to LD and did not cause morphological changes on the LD surface. Key words:Lithium disilicate, glass ceramics, acid etching, shear bond strength, scanning electron microscopy. PMID:24455073

Morphological, anatomical, and ultrastructural changes (visualized through scanning electron microscopy) induced in Triticum aestivum by Pb²⁺ treatment.

PubMed

Kaur, Gurpreet; Singh, Harminder Pal; Batish, Daizy Rani; Kohli, Ravinder Kumar

2014-11-01

Lead (Pb) causes severe damage to crops, ecosystems, and humans, and alters the physiology and biochemistry of various plant species. It is hypothesized that Pb-induced metabolic alterations could manifest as structural variations in the roots of plants. In light of this, the morphological, anatomical, and ultrastructural variations (through scanning electron microscopy, SEM) were studied in 4-day-old seedlings of Triticum aestivum grown under Pb stress (0, 8, 16, 40, and 80 mg Pb(2+) l(-1); mild to highly toxic). The toxic effect was more pronounced in radicle growth than on the plumule growth. The SEM of the root of T. aestivum depicted morphological alterations and surface ultrastructural changes. Compared to intact and uniform surface cells in the control roots, cells were irregular and desiccated in Pb(2+)-treated roots. In Pb(2+)-treated roots, the number of root hairs increased manifold, showing dense growth, and these were apparently longer. Apart from the deformity in surface morphology and anatomy of the roots in response to Pb(2+) toxicity, considerable anatomical alterations were also observed. Pb(2+)-treated root exhibited signs of injury in the form of cell distortion, particularly in the cortical cells. The endodermis and pericycle region showed loss of uniformity post Pb(2+) exposure (at 80 mg l(-1) Pb(2+)). The cells appeared to be squeezed with greater depositions observed all over the tissue. The study concludes that Pb(2+) treatment caused structural anomalies and induced anatomical and surface ultrastructural changes in T. aestivum.

Historical GIS Data and Changes in Urban Morphological Parameters for the Analysis of Urban Heat Islands in Hong Kong

NASA Astrophysics Data System (ADS)

Peng, F.; Wong, M. S.; Nichol, J. E.; Chan, P. W.

2016-06-01

Rapid urban development between the 1960 and 2010 decades have changed the urban landscape and pattern in the Kowloon Peninsula of Hong Kong. This paper aims to study the changes of urban morphological parameters between the 1985 and 2010 and explore their influences on the urban heat island (UHI) effect. This study applied a mono-window algorithm to retrieve the land surface temperature (LST) using Landsat Thematic Mapper (TM) images from 1987 to 2009. In order to estimate the effects of local urban morphological parameters to LST, the global surface temperature anomaly was analysed. Historical 3D building model was developed based on aerial photogrammetry technique using aerial photographs from 1964 to 2010, in which the urban digital surface models (DSMs) including elevations of infrastructures and buildings have been generated. Then, urban morphological parameters (i.e. frontal area index (FAI), sky view factor (SVF)), vegetation fractional cover (VFC), global solar radiation (GSR), Normalized Difference Built-Up Index (NDBI), wind speed were derived. Finally, a linear regression method in Waikato Environment for Knowledge Analysis (WEKA) was used to build prediction model for revealing LST spatial patterns. Results show that the final apparent surface temperature have uncertainties less than 1 degree Celsius. The comparison between the simulated and actual spatial pattern of LST in 2009 showed that the correlation coefficient is 0.65, mean absolute error (MAE) is 1.24 degree Celsius, and root mean square error (RMSE) is 1.51 degree Celsius of 22,429 pixels.

Electrocatalytic reduction of carbon dioxide on electrodeposited tin-based surfaces

NASA Astrophysics Data System (ADS)

Alba, Bianca Christina S.; Camayang, John Carl A.; Mopon, Marlon L.; del Rosario, Julie Anne D.

2017-08-01

The electrocatalytic reduction of carbon dioxide to small organic molecular compounds provides a means of generating alternative fuel source while suppressing climate change. Suitable catalysts, however, are necessary to optimize its reaction kinetics towards more valuable products. Consequently, in this study, electrodeposited Sn electrodes have been developed as catalysts for CO2 electroreduction. Deposition potential was varied to produce different Sn catalysts. SEM showed varying morphologies and increasing amount as the applied potential becomes more negative. Cyclic voltammetry and chronoamperometry showed that the activity and stability of the catalysts towards CO2 reduction depend on the morphology and presence of tin oxides. These results provide a better understanding on the performance of electrodeposited Sn-based surfaces as catalysts for CO2 reduction.

Controlling Film Morphology in Conjugated Polymer

PubMed Central

Park, Lee Y.; Munro, Andrea M.; Ginger, David S.

2009-01-01

We study the effects of patterned surface chemistry on the microscale and nanoscale morphology of solution-processed donor/acceptor polymer-blend films. Focusing on combinations of interest in polymer solar cells, we demonstrate that patterned surface chemistry can be used to tailor the film morphology of blends of semiconducting polymers such as poly-[2-(3,7-dimethyloctyloxy)-5-methoxy-p-phenylenevinylene] (MDMO-PPV), poly-3-hexylthiophene (P3HT), poly[(9,9-dioctylflorenyl-2,7-diyl)-co-benzothiadiazole)] (F8BT), and poly(9,9-dioctylfluorene-co-bis-N,N’-(4-butylphenyl)-bis-N,N’-phenyl-1,4-phenylendiamine) (PFB) with the fullerene derivative, [6,6]-phenyl-C61-butyric acid methyl ester (PCBM). We present a method for generating patterned, fullerene-terminated monolayers on gold surfaces, and use microcontact printing and Dip-Pen Nanolithography (DPN) to pattern alkanethiols with both micro- and nanoscale features. After patterning with fullerenes and other functional groups, we backfill the rest of the surface with a variety of thiols to prepare substrates with periodic variations in surface chemistry. Spin coating polymer:PCBM films onto these substrates, followed by thermal annealing under nitrogen, leads to the formation of structured polymer films. We characterize these films with Atomic Force Microscopy (AFM), Raman spectroscopy, and fluorescence microscopy. The surface patterns are effective in guiding phase separation in all of the polymer:PCBM systems investigated, and lead to a rich variety of film morphologies that are inaccessible with unpatterned substrates. We demonstrate our ability to guide pattern formation in films thick enough of be of interest for actual device applications (up to 200 nm in thickness) using feature sizes as small as 100 nm. Finally, we show that the surface chemistry can lead to variations in film morphology on length scales significantly smaller than those used in generating the original surface patterns. The variety of behaviors observed and the wide range of control over polymer morphology achieved at a variety of different length scales have important implications for the development of bulk heterojunction solar cells. PMID:18983150

Surface Characterization of Mechanochemically Modified Exfoliated Halloysite Nanoscrolls.

PubMed

Zsirka, Balázs; Táborosi, Attila; Szabó, Péter; Szilágyi, Róbert K; Horváth, Erzsébet; Juzsakova, Tatjána; Fertig, Dávid; Kristóf, János

2017-04-11

Surface modifications fundamentally influence the morphology of kaolinite nanostructures as a function of crystallinity and the presence of contaminants. Besides morphology, the catalytic properties of 1:1-type exfoliated aluminosilicates are also influenced by the presence of defect sites that can be generated in a controlled manner by mechanochemical activation. In this work, we investigated exfoliated halloysite nanoparticles with a quasi-homogeneous, scroll-type secondary structure toward developing structural/functional relationships for composition, atomic structure, and morphology. The surface properties of thin-walled nanoscrolls were studied as a function of mechanochemical activation expressed by the duration of dry-grinding. The surface characterizations were carried out using N 2 , NH 3 , and CO 2 adsorption measurements. The effects of grinding on the nanohalloysite structure were followed using thermoanalytical thermogravimetric/derivative thermogravimetric (TG/DTG) and infrared spectroscopic [Fourier transform infrared/attenuated total reflection (FTIR/ATR)] techniques. Grinding results in partial dehydroxylation with similar changes as those observed for heat treatment above 300 °C. Mechanochemical activation shows a decrease in the dehydroxylation mass loss and the DTG peak temperature, a decrease in the specific surface area and the number of mesopores, an increase in the surface acidity, blue shift of surface hydroxide bands, and a decrease in the intensity of FTIR/ATR bands as a function of the grinding time. The experimental observations were used to guide atomic-scale structural and energetic simulations using realistic molecular cluster models for a nanohalloysite particle. A full potential energy surface description was developed for the mechanochemical activation and/or heating toward nanometahalloysite formation that aids the interpretation of experimental results. The calculated differences upon dehydroxylation show a remarkable agreement with the mass loss values from DTG measurements.

Biocompatibility of modified ultra-high-molecular-weight polyethylene

NASA Astrophysics Data System (ADS)

Novotná, Z.; Lacmanová, V.; Rimpelová, S.; Juřik, P.; Polívková, M.; Å vorčik, V.

2016-09-01

Ultra-high-molecular-weight polyethylene (UHMWPE, PE) is a synthetic polymer used for biomedical applications because of its high impact resistance, ductility and stability in contact with physiological fluids. Therefore this material is being used in human orthopedic implants such as total joint replacements. Surface modification of this material relates to changes of its surface hydrophilicity, energy, microstructure, roughness, and morphology, all influencing its biological response. In our recent work, PE was treated by an Ar+ plasma discharge and then grafted with biologically active polyethylene glycol in order to enhance adhesion and proliferation of mouse fibroblast (L929). The surface properties of pristine PE and its grafted counterparts were studied by goniometry (surface wettability). Furthermore, Atomic Force Microscopy was used to determine the surface morphology and roughness. The biological response of the L929 cell lines seeded on untreated and plasma treated PE matrices was quantified in terms of the cell adhesion, density, and metabolic activity. Plasma treatment leads to the ablation of the polymer surface layers. Plasma treatment and subsequent poly(ethylene glycol) grafting lead to dramatic changes in the polymer surface morphology and roughness. Biological tests, performed in vitro, show increased adhesion and proliferation of cells on modified polymers. Grafting with poly(ethylene glycol) increases cell proliferation compared to plasma treatment.

Multipulse nanosecond laser irradiation of silicon for the investigation of surface morphology and photoelectric properties

NASA Astrophysics Data System (ADS)

Sardar, Maryam; Chen, Jun; Ullah, Zaka; Jelani, Mohsan; Tabassum, Aasma; Cheng, Ju; Sun, Yuxiang; Lu, Jian

2017-12-01

We irradiate the single crystal boron-doped silicon (Si) with different number of laser pulses at constant fluence (7.5 J cm-2) in ambient air using Nd:YAG laser and examine its surface morphology and photoelectric properties in details. The results obtained from optical micrographs reveal the increase in heat affected zone (HAZ) and melted area of laser irradiated Si with increasing number of laser pulses. The SEM micrographs evidence the formation of various surface morphologies like laser induced periodic surface structures, crater, microcracks, clusters, cavities, pores, trapped bubbles, nucleation sites, micro-bumps, redeposited material and micro- and nano-particles on the surface of irradiated Si. The surface profilometry analysis informs that the depth of crater is increased with increase in number of incident laser pulses. The spectroscopic ellipsometry reveals that the multipulse irradiation of Si changes its optical properties (refractive index and extinction coefficient). The current-voltage (I-V) characteristic curves of laser irradiated Si show that although the multipulse laser irradiation produces considerable number of surface defects and damages, the electrical properties of Si are well sustained after the multipulse irradiation. The current findings suggest that the multipulse irradiation can be an effective way to tune the optical properties of Si for the fabrication of wide range of optoelectronic devices.

The effect of sibutramine on platelet morphology of Spraque-Dawley rats fed a high energy diet.

PubMed

Oberholzer, Hester Magdalena; Van Der Schoor, Ciska; Pretorius, Etheresia

2013-06-01

The aim of this study was to investigate the effect of Sibutramine on platelet ultrastructure and discuss the morphological observations in relation to known physiological effects of the compound. Six-week-old, female Spraque-Dawley rats were used in this study. The animals were placed on a high energy diet after which sibutramine administration followed. Blood was drawn on the day of termination and platelet rich plasma was obtained to prepare plasma smears for analysis. Scanning electron microscopy was used to investigate the ultrastructure of the platelets. Platelets of the Sibutramine-treated animals showed smooth surface with limited pseudopodia formation when compared with that of the control animals. Higher magnification of the platelet surface showed membrane tears and swelling, typically seen in necrotic cells. It can therefore be concluded from these results that Sibutramine alters the membrane morphology of platelets to that typical of necrotic cells. Copyright © 2013 Wiley Periodicals, Inc.

Surface smoothing of indium tin oxide film by laser-induced photochemical etching

NASA Astrophysics Data System (ADS)

Kang, JoonHyun; Kim, Young-Hwan; Kwon, Seok Joon; Park, Joon-Suh; Park, Kyoung Wan; Park, Jae-Gwan; Han, Il Ki

2017-12-01

Surface smoothing of indium tin oxide (ITO) film by laser irradiation was demonstrated. The ITO surface was etched by choline radicals, which were activated by laser irradiation at a wavelength of 532 nm. The RMS surface roughness was improved from 5.6 to 4.6 nm after 10 min of laser irradiation. We also showed the changes in the surface morphology of the ITO film with various irradiation powers and times.

Studies of SERS efficiency of gold coated porous silicon formed on rough silicon backside

NASA Astrophysics Data System (ADS)

Dridi, H.; Haji, L.; Moadhen, A.

2017-12-01

Starting from a rough backside of silicon wafer, we have formed a porous layer by electrochemical anodization and then coated by a thin film of gold. The morphological characteristics of the porous silicon and in turn the metal film are governed by the anodization process and also by the starting surface. So, in order to investigate the Plasmonic aspect of such rough surface which combines roughness inherent to the porous nature and that due to rough starting surface, we have used a dye target molecule to study its SERS signal using a porous silicon layer obtained on the rough backside surface. The use of unusual backside of silicon wafer could be, beside the others, an interesting way to made SERS effective substrate thanks to reproducible rough porous gold on porous layer from this starting face. The morphological results correspond to the silicon rough surface as a function of the crystallographic orientation showed the presence of two different substrate structure. The optical reflectivity results obtained of gold deposited on oxidized porous silicon showed a dependence of its Localized Surface Plasmon band frequency of the deposit time. SERS results, obtained for a dye target molecule (Rhodamine 6G), show a higher intensities in the case of the 〈110〉 orientation, which characterized by the higher roughness surface. Voici "the most relevant and important aspects of our work".

Channel morphology effect on water transport through graphene bilayers.

PubMed

Liu, Bo; Wu, Renbing; Law, Adrian Wing-Keung; Feng, Xi-Qiao; Bai, Lichun; Zhou, Kun

2016-12-08

The application of few-layered graphene-derived functional thin films for molecular filtration and separation has recently attracted intensive interests. In practice, the morphology of the nanochannel formed by the graphene (GE) layers is not ideally flat and can be affected by various factors. This work investigates the effect of channel morphology on the water transport behaviors through the GE bilayers via molecular dynamics simulations. The simulation results show that the water flow velocity and transport resistance highly depend on the curvature of the graphene layers, particularly when they are curved in non-synergic patterns. To understand the channel morphology effect, the distributions of water density, dipole moment orientation and hydrogen bonds inside the channel are investigated, and the potential energy surface with different distances to the basal GE layer is analyzed. It shows that the channel morphology significantly changes the distribution of the water molecules and their orientation and interaction inside the channel. The energy barrier for water molecules transport through the channel also significantly depends on the channel morphology.

Channel morphology effect on water transport through graphene bilayers

PubMed Central

Liu, Bo; Wu, Renbing; Law, Adrian Wing-Keung; Feng, Xi-Qiao; Bai, Lichun; Zhou, Kun

2016-01-01

The application of few-layered graphene-derived functional thin films for molecular filtration and separation has recently attracted intensive interests. In practice, the morphology of the nanochannel formed by the graphene (GE) layers is not ideally flat and can be affected by various factors. This work investigates the effect of channel morphology on the water transport behaviors through the GE bilayers via molecular dynamics simulations. The simulation results show that the water flow velocity and transport resistance highly depend on the curvature of the graphene layers, particularly when they are curved in non-synergic patterns. To understand the channel morphology effect, the distributions of water density, dipole moment orientation and hydrogen bonds inside the channel are investigated, and the potential energy surface with different distances to the basal GE layer is analyzed. It shows that the channel morphology significantly changes the distribution of the water molecules and their orientation and interaction inside the channel. The energy barrier for water molecules transport through the channel also significantly depends on the channel morphology. PMID:27929106

Influences of MAA on the porous morphology of P(St-MAA) latex particles produced by batch soap-free emulsion polymerization followed by stepwise alkali/acid post-treatment.

PubMed

Deng, Wei; Li, Ronglong; Zhang, Mengjun; Gong, Lixiang; Kan, Chengyou

2010-09-01

Soap-free P(St-MAA) latex particles with variable styrene (St)/methacrylic acid (MAA) ratio were synthesized by batch emulsion copolymerization at 70 degrees C for 7h, and the particles with porous structure were obtained after stepwise alkali/acid post-treatment. The effects of MAA amount on the particle morphologies after the alkali and the stepwise alkali/acid post-treatments were investigated by transmission electron microscopy (TEM) and scanning electron microscopy (SEM). Results indicated that the alkali-treated latex particles showed anomalous structure with rough surface, and no hollow was clearly identified inside them. When these alkali-treated particles were further treated with acid solution, the particle surface became much smoother, and porous morphology appeared. It was found that when the MAA amount was less than or equal to 4mol%, no obvious morphological variation was observed; while the latex particles showed clearly porous structure as the MAA amount increased to 6mol%; with the further increase of MAA amount to 8mol%, the pore size decreased distinctly. Copyright 2010 Elsevier Inc. All rights reserved.

Uniting Superhydrophobic, Superoleophobic and Lubricant Infused Slippery Behavior on Copper Oxide Nano-structured Substrates

PubMed Central

Ujjain, Sanjeev Kumar; Roy, Pritam Kumar; Kumar, Sumana; Singha, Subhash; Khare, Krishnacharya

2016-01-01

Alloys, specifically steel, are considered as the workhorse of our society and are inimitable engineering materials in the field of infrastructure, industry and possesses significant applications in our daily life. However, creating a robust synthetic metallic surface that repels various liquids has remained extremely challenging. The wettability of a solid surface is known to be governed by its geometric nano-/micro structure and the chemical composition. Here, we are demonstrating a facile and economical way to generate copper oxide micro-nano structures with spherical (0D), needle (1D) and hierarchical cauliflower (3D) morphologies on galvanized steel substrates using a simple chemical bath deposition method. These nano/micro textured steel surfaces, on subsequent coating of a low surface energy material display excellent superhydrophobic, superoleophobic and slippery behavior. Polydimethylsiloxane coated textured surfaces illustrate superhydrophobicity with water contact angle about 160°(2) and critical sliding angle ~2°. When functionalized with low-surface energy perfluoroalkylsilane, these surfaces display high repellency for low surface tension oils as well as hydrocarbons. Among them, the hierarchical cauliflower morphology exhibits re-entrant structure thereby showing the best superoleophobicity with contact angle 149° for dodecane. Once infused with a lubricant like silicone oil, they show excellent slippery behavior with low contact angle hysteresis (~ 2°) for water drops. PMID:27752098

Uniting Superhydrophobic, Superoleophobic and Lubricant Infused Slippery Behavior on Copper Oxide Nano-structured Substrates

NASA Astrophysics Data System (ADS)

Ujjain, Sanjeev Kumar; Roy, Pritam Kumar; Kumar, Sumana; Singha, Subhash; Khare, Krishnacharya

2016-10-01

Alloys, specifically steel, are considered as the workhorse of our society and are inimitable engineering materials in the field of infrastructure, industry and possesses significant applications in our daily life. However, creating a robust synthetic metallic surface that repels various liquids has remained extremely challenging. The wettability of a solid surface is known to be governed by its geometric nano-/micro structure and the chemical composition. Here, we are demonstrating a facile and economical way to generate copper oxide micro-nano structures with spherical (0D), needle (1D) and hierarchical cauliflower (3D) morphologies on galvanized steel substrates using a simple chemical bath deposition method. These nano/micro textured steel surfaces, on subsequent coating of a low surface energy material display excellent superhydrophobic, superoleophobic and slippery behavior. Polydimethylsiloxane coated textured surfaces illustrate superhydrophobicity with water contact angle about 160°(2) and critical sliding angle ~2°. When functionalized with low-surface energy perfluoroalkylsilane, these surfaces display high repellency for low surface tension oils as well as hydrocarbons. Among them, the hierarchical cauliflower morphology exhibits re-entrant structure thereby showing the best superoleophobicity with contact angle 149° for dodecane. Once infused with a lubricant like silicone oil, they show excellent slippery behavior with low contact angle hysteresis (~ 2°) for water drops.

Femtosecond laser-induced blazed periodic grooves on metals.

PubMed

Hwang, Taek Yong; Guo, Chunlei

2011-07-01

In this Letter, we generate laser-induced periodic surface structures (LIPSSs) on platinum following femtosecond laser pulse irradiation. For the first time to our knowledge, we study the morphological profile of LIPSSs over a broad incident angular range, and find that the morphological profile of LIPSSs depends significantly on the incident angle of the laser beam. We show that LIPSS grooves become more asymmetric at a larger incident angle, and the morphological profile of LIPSSs formed at an incident angle over 55° eventually resembles that of a blazed grating. Our study suggests that the formation of the blazed groove structures is attributed to the selective ablation of grooves through the asymmetric periodic surface heating following femtosecond pulse irradiation. The blazed grooves are useful for controlling the diffraction efficiency of LIPSSs.

Control of periodic surface structures on silicon by combined temporal and polarization shaping of femtosecond laser pulses

NASA Astrophysics Data System (ADS)

Fraggelakis, F.; Stratakis, E.; Loukakos, P. A.

2018-06-01

We demonstrate the capability to exercise advanced control on the laser-induced periodic surface structures (LIPSS) on silicon by combining the effect of temporal shaping, via tuning the interpulse temporal delay between double femtosecond laser pulses, along with the independent manipulation of the polarization state of each of the individual pulses. For this, cross-polarized (CP) as well as counter-rotating (CR) double circularly polarized pulses have been utilized. The pulse duration was 40 fs and the central wavelength of 790 nm. The linearly polarized double pulses are generated by a modified Michelson interferometer allowing the temporal delay between the pulses to vary from Δτ = -80 ps to Δτ = +80 ps with an accuracy of 0.2 fs. We show the significance of fluence balance between the two pulse components and its interplay with the interpulse delay and with the order of arrival of the individually polarized pulse components of the double pulse sequence on the final surface morphology. For the case of CR pulses we found that when the pulses are temporally well separated the surface morphology attains no axial symmetry. But strikingly, when the two CP pulses temporally overlap, we demonstrate, for the first time in our knowledge, the detrimental effect that the phase delay has on the ripple orientation. Our results provide new insight showing that temporal pulse shaping in combination with polarization control gives a powerful tool for drastically controlling the surface nanostructure morphology.

Martian stepped-delta formation by rapid water release.

PubMed

Kraal, Erin R; van Dijk, Maurits; Postma, George; Kleinhans, Maarten G

2008-02-21

Deltas and alluvial fans preserved on the surface of Mars provide an important record of surface water flow. Understanding how surface water flow could have produced the observed morphology is fundamental to understanding the history of water on Mars. To date, morphological studies have provided only minimum time estimates for the longevity of martian hydrologic events, which range from decades to millions of years. Here we use sand flume studies to show that the distinct morphology of martian stepped (terraced) deltas could only have originated from a single basin-filling event on a timescale of tens of years. Stepped deltas therefore provide a minimum and maximum constraint on the duration and magnitude of some surface flows on Mars. We estimate that the amount of water required to fill the basin and deposit the delta is comparable to the amount of water discharged by large terrestrial rivers, such as the Mississippi. The massive discharge, short timescale, and the associated short canyon lengths favour the hypothesis that stepped fans are terraced delta deposits draped over an alluvial fan and formed by water released suddenly from subsurface storage.

Various nanoparticle morphologies and surface properties of waterborne polyurethane controlled by water

PubMed Central

Zhou, Xing; Fang, Changqing; Lei, Wanqing; Du, Jie; Huang, Tingyi; Li, Yan; Cheng, Youliang

2016-01-01

Water plays important roles in organic reactions such as polyurethane synthesis, and the aqueous solution environment affects polymer morphology and other properties. This paper focuses on the morphology and surface properties of waterborne polyurethane resulting from the organic reaction in water involving different forms (solid and liquid), temperatures and aqueous solutions. We provide evidence from TEM observations that the appearance of polyurethane nanoparticles in aqueous solutions presents diverse forms, including imperfect spheres, perfect spheres, perfect and homogenous spheres and tubes. Based on the results on FTIR, GPC, AFM and XRD experiments, we suggest that the shape of the nanoparticles may be decided by the crimp degree (i.e., the degree of polyurethane chains intertangling in the water environment) and order degree, which are determined by the molecular weight (Mn) and hydrogen bonds. Meanwhile, solid water and high-temperature water can both reduce hard segments that gather on the polyurethane film surface to reduce hydrophilic groups and produce a soft surface. Our findings show that water may play key roles in aqueous polymer formation and bring order to molecular chains. PMID:27687001

The effect of thermal and organic additive in morphology of ceramic based silicate

NASA Astrophysics Data System (ADS)

Ginting, J.; Bangun, N.; Sembiring, H. Br; Putri, N. K.

2017-04-01

M-Silicate (M = Mg, Ca) has been prepared by exchange metal reaction from M-Chloride salts and sodium silicate. The resulting white solid of chloride salts then heated at 700, 800, 900 and 1000 °C. Due to increase the porosity of M-Silicate, 1,2-propanediol, oleic acid and glycerol were added, then formed M-silicates were heated at 800 °C. Then, obtained white solid M-Silicates were characterized by Scanning Electron Microscopy (SEM). SEM images show the variance of surface morphology when the temperature increases. The addition of organic compounds is involved in surface modification.

Effect of bath temperature on surface morphology and photocatalytic activity of ZnO nanorods

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

Sriharan, N.; Senthil, T. S., E-mail: tssenthi@gmail.com; Muthukumarasamy, N.

2016-05-06

ZnO nanorods were prepared by using simple hydrothermal method using four different bath temperatures. All the prepared ZnO nanorods are annealed at 450°C and are characterized by using various techniques such as X-ray diffraction, UV spectra and scanning electron microscopy. Photocatalytic activity of the prepared ZnO nanorods is analyzed. A novel photocatalytic reactor designed with ZnO nanorods prepared at 90°C shows enhanced catalytic efficiency. The role of light irradiation time, bath temperature and surface morphology of the ZnO nanorods on the performance of photocatalytic reaction is analyzed.

Growth mechanism of surface roughed platinum nanowires through electrodeposition current control and their electrochemical applications

NASA Astrophysics Data System (ADS)

Ruan, Dajiang

The aim of this work is to investigate the effect of current density on the grain size and surface morphology of electrodeposited platinum nanowires and their applications. Platinum (Pt) nanowires were fabricated by a galvanostatic electrodeposition method in a porous anodic alumina oxide (AAO) template with different current densities. Both direct current and pulse current electrodeposition were used to synthesize the Pt nanowires. The grain size and surface morphology of the Pt nanowires were studied by field emission scanning electron microscopy (FE-SEM), transmission electron microcopy (TEM) and X-ray diffraction (XRD). The experimental results showed that the current density was the key factor to control the surface roughness. The surface of the Pt nanowires became rougher and the grain sizes were increased by increasing the current densities. From the experimental results, a growth mechanism of Pt nanowires based on progressive nucleation and crystallization was proposed in order to find out the relationship between the surface morphology and current density. The electrochemical properties and catalytic activities of these surface roughed Pt nanowires were investigated in the detection of H20 2 and for the methanol oxidation. Cyclic voltammograms of Pt nanowire modified electrodes were obtained using a potentiostat, which showed that rougher Pt nanowires have higher response and better activity than that of smooth nanowires. For H202 detection, the effect of scan rate and H202 concentration were studied and it was found that the peak current for hydrogen peroxide reduction became larger with the increasing of either scan rate or H202 concentration. It can be inferred that the process of electrocatalytic hydrogen peroxide reduction may be controlled by diffusion of hydrogen peroxide and the Pt nanowire modified glassy carbon electrode (GCE) is well suited for the detection of H202. From the relationship between the peak current and square root of scan rates for methanol oxidation, it can be inferred that the process of electrocatalytic methanol oxidation was controlled by diffusion of methanol. To understand the effect of the morphological feature on the electrocatalytic activity of the Pt nanowire catalysts, the electrochemically active surface area (ECSA) as a function of deposited current density was investigated, which suggests that Pt nanowire catalysts deposited at highest current density had the most ECSA surface morphology of the Pt nanowires. The chronoamperometric curves and electrochemical impedance spectroscopy (EIS) results confirmed that the Pt nanowire catalyst synthesized at higher current density possessed longer durability and gave more efficient electrochemical performance.

In situ X-ray nanotomography of metal surfaces during electropolishing

DOE PAGES

Nave, Maryana I.; Allen, Jason P.; Karen Chen-Wiegart, Yu-chen; ...

2015-10-15

A low voltage electropolishing of metal wires is attractive for nanotechnology because it provides centimeter long and micrometer thick probes with the tip radius of tens of nanometers. Using X-ray nanotomography we studied morphological transformations of the surface of tungsten wires in a specially designed electrochemical cell where the wire is vertically submersed into the KOH electrolyte. We show that stability and uniformity of the probe span is supported by a porous shell growing at the surface of tungsten oxide and shielding the wire surface from flowing electrolyte. We discovered that the kinetics of shell growth at the triple line,more » where meniscus meets the wire, is very different from that of the bulk of electrolyte. Many metals follow similar electrochemical transformations hence the discovered morphological transformations of metal surfaces are expected to play significant role in many natural and technological applications.« less

Computer-assisted quantification of the skull deformity for craniosynostosis from 3D head CT images using morphological descriptor and hierarchical classification

NASA Astrophysics Data System (ADS)

Lee, Min Jin; Hong, Helen; Shim, Kyu Won; Kim, Yong Oock

2017-03-01

This paper proposes morphological descriptors representing the degree of skull deformity for craniosynostosis in head CT images and a hierarchical classifier model distinguishing among normal and different types of craniosynostosis. First, to compare deformity surface model with mean normal surface model, mean normal surface models are generated for each age range and the mean normal surface model is deformed to the deformity surface model via multi-level threestage registration. Second, four shape features including local distance and area ratio indices are extracted in each five cranial bone. Finally, hierarchical SVM classifier is proposed to distinguish between the normal and deformity. As a result, the proposed method showed improved classification results compared to traditional cranial index. Our method can be used for the early diagnosis, surgical planning and postsurgical assessment of craniosynostosis as well as quantitative analysis of skull deformity.

Designing robust alumina nanowires-on-nanopores structures: superhydrophobic surfaces with slippery or sticky water adhesion.

PubMed

Peng, Shan; Tian, Dong; Miao, Xinrui; Yang, Xiaojun; Deng, Wenli

2013-11-01

Hierarchical alumina surfaces with different morphologies were fabricated by a simple one-step anodization method. These alumina films were fabricated by a new raw material: silica gel plate (aluminum foil with a low purity of 97.17%). The modulation of anodizing time enabled the formation of nanowires-on-nanopores hybrid nanostructures having controllable nanowires topographies through a self-assembly process. The resultant structures were demonstrated to be able to achieve superhydrophobicity without any hydrophobic coating layer. More interestingly, it is found that the as-prepared superhydrophobic alumina surfaces exhibited high contrast water adhesion. Hierarchical alumina film with nanowire bunches-on-nanopores (WBOP) morphology presents extremely slippery property which can obtain a sliding angle (SA) as low as 1°, nanowire pyramids-on-nanopores (WPOP) structure shows strongly sticky water adhesion with the adhesive ability to support 15 μL inverted water droplet at most. The obtained superhydrophobic alumina surfaces show remarkable mechanical durability even treated by crimping or pressing without impact on the water-repellent performance. Moreover, the created surfaces also show excellent resistivity to ice water, boiling water, high temperature, organic solvent and oil contamination, which could expand their usefulness and efficacy in harsh conditions. Copyright © 2013 Elsevier Inc. All rights reserved.

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.

Distribution of olfactory epithelium in the primate nasal cavity: are microsmia and macrosmia valid morphological concepts?

PubMed

Smith, Timothy D; Bhatnagar, Kunwar P; Tuladhar, Praphul; Burrows, Annie M

2004-11-01

The terms "microsmatic" and "macrosmatic" are used to compare species with greater versus lesser olfactory capabilities, such as carnivores compared to certain primates. These categories have been morphologically defined based on the size of olfactory bulb and surface area of olfactory epithelium in the nasal fossa. The present study examines assumptions regarding the morphological relationship of bony elements to the olfactory mucosa, the utility of olfactory epithelial surface area as a comparative measurement, and the utility of the microsmatic concept. We examined the distribution of olfactory neuroepithelium (OE) across the anteroposterior length of the nasal fossa (from the first completely enclosed cross-section of the nasal fossa to the choanae) in the microsmatic marmoset (Callithrix jacchus) compared to four species of nocturnal strepsirrhines (Otolemur crassicaudatus, O. garnetti, Microcebus murinus, and Cheirogaleus medius). Adults of all species were examined and infant C. jacchus, O. crassicaudatus, M. murinus, and C. medius were also examined. All specimens were serially sectioned in the coronal plane and prepared for light microscopic study. Distribution of OE across all the turbinals, nasal septal surfaces, and accessory spaces of the nasal chamber was recorded for each specimen. The right nasal fossae of one adult C. jacchus and one neonatal M. murinus were also three-dimensionally reconstructed using Scion Image software to reveal OE distribution. Findings showed OE to be distributed relatively more anteriorly in adult C. jacchus compared to strepsirrhines. It was also distributed more anteriorly along the nasal septal walls and recesses in neonates than adults. Our findings also showed that OE surface area was not a reliable proxy for receptor neuron numbers due to differing OE thickness among species. Such results indicate that nasal cavity morphology must be carefully reconsidered regarding traditional functional roles (olfaction versus air conditioning) assigned to various nasal cavity structures. At present, the microsmatic concept itself lacks a basis in nasal chamber morphology, since OE may have varying patterns of distribution among different primates. (c) 2004 Wiley-Liss, Inc.

NanoTopoChip: High-throughput nanotopographical cell instruction.

PubMed

Hulshof, Frits F B; Zhao, Yiping; Vasilevich, Aliaksei; Beijer, Nick R M; de Boer, Meint; Papenburg, Bernke J; van Blitterswijk, Clemens; Stamatialis, Dimitrios; de Boer, Jan

2017-10-15

Surface topography is able to influence cell phenotype in numerous ways and offers opportunities to manipulate cells and tissues. In this work, we develop the Nano-TopoChip and study the cell instructive effects of nanoscale topographies. A combination of deep UV projection lithography and conventional lithography was used to fabricate a library of more than 1200 different defined nanotopographies. To illustrate the cell instructive effects of nanotopography, actin-RFP labeled U2OS osteosarcoma cells were cultured and imaged on the Nano-TopoChip. Automated image analysis shows that of many cell morphological parameters, cell spreading, cell orientation and actin morphology are mostly affected by the nanotopographies. Additionally, by using modeling, the changes of cell morphological parameters could by predicted by several feature shape parameters such as lateral size and spacing. This work overcomes the technological challenges of fabricating high quality defined nanoscale features on unprecedented large surface areas of a material relevant for tissue culture such as PS and the screening system is able to infer nanotopography - cell morphological parameter relationships. Our screening platform provides opportunities to identify and study the effect of nanotopography with beneficial properties for the culture of various cell types. The nanotopography of biomaterial surfaces can be modified to influence adhering cells with the aim to improve the performance of medical implants and tissue culture substrates. However, the necessary knowledge of the underlying mechanisms remains incomplete. One reason for this is the limited availability of high-resolution nanotopographies on relevant biomaterials, suitable to conduct systematic biological studies. The present study shows the fabrication of a library of nano-sized surface topographies with high fidelity. The potential of this library, called the 'NanoTopoChip' is shown in a proof of principle HTS study which demonstrates how cells are affected by nanotopographies. The large dataset, acquired by quantitative high-content imaging, allowed us to use predictive modeling to describe how feature dimensions affect cell morphology. Copyright © 2017 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

Biodegradation of orthodontic metallic brackets and associated implications for friction.

PubMed

Regis, Saulo; Soares, Paulo; Camargo, Elisa S; Guariza Filho, Odilon; Tanaka, Orlando; Maruo, Hiroshi

2011-10-01

This study aimed to assess the effect of clinical exposure on the surface morphology, dimensions, and frictional behavior of metallic orthodontic brackets. Ninety-five brackets, of 3 commercial brands, were retrieved from patients who had finished orthodontic treatment. As-received brackets, matched by type and brand, were used for comparisons. Surface morphology and precipitated material were analyzed by optical and scanning electron microscopy and x-ray microanalysis. Bracket dimensions were measured with a measuring microscope. Resistance to sliding on a stainless steel wire was assessed. Retrieved brackets showed surface alterations from corrosion, wear, and plastic deformation, especially in the external slot edges. Film deposition over the alloy surface was observed to a variable extent. The main elements in the film were carbon, oxygen, calcium, and phosphorus. The as-received brackets showed differences (P <0.05) in the slot sizes among brands, and 1 brand showed a 3% increase in the retrieved brackets' slots. The frictional behavior differed among brands. Retrieved brackets of 2 brands showed 10% to 20% increases in resistance to sliding. Metallic brackets undergo significant degradation during orthodontic treatment, possibly with increased friction. At present, it is difficult to predict the impact of these changes on the clinical performance of orthodontic components. Copyright © 2011 American Association of Orthodontists. Published by Mosby, Inc. All rights reserved.

Investigation of submerged waterjet cavitation through surface property and flow information in ambient water

NASA Astrophysics Data System (ADS)

Kang, Can; Liu, Haixia; Zhang, Tao; Li, Qing

2017-12-01

To illuminate primary factors influencing the morphology of the surface impinged by submerged waterjet, experiments were performed at high jet pressures from 200 to 320 MPa. The cavitation phenomenon involved in the submerged waterjet was emphasized. Copper specimens were used as the targets enduring the impingement of high-pressure waterjets. The microhardness of the specimen was measured. Surface morphology was observed using an optical profiling microscope. Pressure fluctuations near the jet stream were acquired with miniature pressure transducers. The results show that microhardness increases with jet pressure and impingement time, and the hardening effect is restricted within a thin layer underneath the target surface. A synthetic effect is testified with the plastic deformation and cavities on the specimen surfaces. Characteristics of different cavitation erosion stages are illustrated by surface morphology. At the same jet pressure, the smallest standoff distance is not corresponding to the highest mass removal rate. Instead, there is an optimal standoff distance. With the increase of jet pressure, overall mass removal rate rises as well. Low-frequency components are predominant in the pressure spectra and the dual-peak pattern is typical. As the streamwise distance from the nozzle is enlarged, pressure amplitudes associated with cavitation bubble collapse are improved.

Human monocyte adhesion and activation on crystalline polymers with different morphology and wettability in vitro.

PubMed

Young, T H; Lin, D T; Chen, L Y

2000-06-15

This study evaluated the effects of crystalline polyamide (Nylon-66), poly(ethylene-co-vinyl alcohol) (PEVA), and poly(vinylidene fluoride) (PVDF) polymers with nonporous and porous morphologies on the ability of monocytes to adhere and subsequently activate to produce IL-1beta, IL-6, and tumor necrosis factor alpha. The results indicated monocyte adhesion and activation on a material might differ to a great extent, depending on the surface morphology and wettability. As the polymer wettability increases, the ability of monocytes to adhere increases but the ability to produce cytokines decreases. Similarly, these polymers, when prepared with porous surfaces, enhance monocyte adhesion but suppress monocyte release of cytokines. Therefore, the hydrophobic PVDF with a nonporous surface stimulates the most activity in adherent monocytes but shows the greatest inhibition of monocyte adhesion when compared with all of the other membranes. In contrast, the hydrophilic Nylon-66, which has a porous surface, is a relatively better substrate for this work. Therefore, monocyte behavior on a biomaterial may be influenced by a specific surface property. Based on this result, we propose that monocyte adhesion is regulated by a different mechanism than monocyte activation. Consequently, the generation of cytokines by monocytes is not proportional to the number of cells adherent to the surface. Copyright 2000 John Wiley & Sons, Inc.

Improved Epitaxy and Surface Morphology in YBa2Cu3Oy Thin Films Grown on Double Buffered Si Wafers

NASA Astrophysics Data System (ADS)

Gao, J.; Kang, L.; Wong, H. Y.; Cheung, Y. L.; Yang, J.

Highly epitaxial thin films of YBCO have been obtained on silicon wafers using a Eu2CuO4/YSZ (yttrium-stabilized ZrO2) double buffer. Our results showed that application of such a double buffer can significantly enhance the epitaxy of grown YBCO. It also leads to an excellent surface morphology. The average surface roughness was found less than 5 nm in a large range. The results of X-ray small angle reflection and positron spectroscpy demonstrate a very clear and flat interface between YBCO and buffer layers. The Eu2CuO4/YSZ double buffer could be promising for coating high-TC superconducting films on various reactive substrates.

Morphology studies of hydrophobic silica on filter surface prepared via spray technique

NASA Astrophysics Data System (ADS)

Shahfiq Zulkifli, Nazrul; Zaini Yunos, Muhamad; Ahmad, Azlinnorazia; Harun, Zawati; Akhair, Siti Hajar Mohd; Adibah Raja Ahmad, Raja; Hafeez Azhar, Faiz; Rashid, Abdul Qaiyyum Abd; Ismail, Al Emran

2017-08-01

This study investigated the effect of the hydrophobic surface treatment effect of air filter performance by using silica aerogel powder as an additive by using spray coating techniques. The membrane characterization tests were carried out on a filter prepared from different additive concentration. Studies on the cross-section and the distribution of particles on the membrane were carried out using a scanning electron microscope (SEM), and the surface morphology was investigated by x-ray spectroscopy (EDS). The results are shown by SEM and EDS that the microstructure filter, especially in the upper layer and sub-layer has been changed. The results also show an increase of hydrophobicity due to the increased quantity of silica aerogel powder.

Morphology, composition and electrical properties of SnO{sub 2}:Cl thin films grown by atomic layer deposition

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

Cheng, Hsyi-En, E-mail: sean@mail.stust.edu.tw; Wen, Chia-Hui; Hsu, Ching-Ming

2016-01-15

Chlorine doped SnO{sub 2} thin films were prepared using atomic layer deposition at temperatures between 300 and 450 °C using SnCl{sub 4} and H{sub 2}O as the reactants. Composition, structure, surface morphology, and electrical properties of the as-deposited films were examined. Results showed that the as-deposited SnO{sub 2} films all exhibited rutile structure with [O]/[Sn] ratios between 1.35 and 1.40. The electrical conductivity was found independent on [O]/[Sn] ratio but dependent on chlorine doping concentration, grain size, and surface morphology. The 300 °C-deposited film performed a higher electrical conductivity of 315 S/cm due to its higher chlorine doping level, larger grain size, andmore » smoother film surface. The existence of Sn{sup 2+} oxidation state was demonstrated to minimize the effects of chlorine on raising the electrical conductivity of films.« less

Experiment and simulation study of laser dicing silicon with water-jet

NASA Astrophysics Data System (ADS)

Bao, Jiading; Long, Yuhong; Tong, Youqun; Yang, Xiaoqing; Zhang, Bin; Zhou, Zupeng

2016-11-01

Water-jet laser processing is an internationally advanced technique, which combines the advantages of laser processing with water jet cutting. In the study, the experiment of water-jet laser dicing are conducted with ns pulsed laser of 1064 nm irradiating, and Smooth Particle Hydrodynamic (SPH) technique by AUTODYN software was modeled to research the fluid dynamics of water and melt when water jet impacting molten material. The silicon surface morphology of the irradiated spots has an appearance as one can see in porous formation. The surface morphology exhibits a large number of cavities which indicates as bubble nucleation sites. The observed surface morphology shows that the explosive melt expulsion could be a dominant process for the laser ablating silicon in liquids with nanosecond pulse laser of 1064 nm irradiating. Self-focusing phenomenon was found and its causes are analyzed. Smooth Particle Hydrodynamic (SPH) modeling technique was employed to understand the effect of water and water-jet on debris removal during water-jet laser machining.

Comparative analysis of surface wax in mature fruits between Satsuma mandarin (Citrus unshiu) and 'Newhall' navel orange (Citrus sinensis) from the perspective of crystal morphology, chemical composition and key gene expression.

PubMed

Wang, Jinqiu; Hao, Haohao; Liu, Runsheng; Ma, Qiaoli; Xu, Juan; Chen, Feng; Cheng, Yunjiang; Deng, Xiuxin

2014-06-15

Surface wax of mature Satsuma mandarin (Citrus unshiu) and 'Newhall' navel orange (Citrus sinensis) was analysed by crystal morphology, chemical composition, and gene expression levels. The epicuticular and total waxes of both citrus cultivars were mostly composed of aldehydes, alkanes, fatty acids and primary alcohols. The epicuticular wax accounted for 80% of the total wax in the Newhall fruits and was higher than that in the Satsuma fruits. Scanning electron microscopy showed that larger and more wax platelets were deposited on the surface of Newhall fruits than on the Satsuma fruits. Moreover, the expression levels of genes involved in the wax formation were consistent with the biochemical and crystal morphological analyses. These diversities of fruit wax between the two cultivars may contribute to the differences of fruit postharvest storage properties, which can provide important information for the production of synthetic wax for citrus fruits. Copyright © 2013 Elsevier Ltd. All rights reserved.

Separating Bulk and Surface Contributions to Electronic Excited-State Processes in Hybrid Mixed Perovskite Thin Films via Multimodal All-Optical Imaging.

PubMed

Simpson, Mary Jane; Doughty, Benjamin; Das, Sanjib; Xiao, Kai; Ma, Ying-Zhong

2017-07-20

A comprehensive understanding of electronic excited-state phenomena underlying the impressive performance of solution-processed hybrid halide perovskite solar cells requires access to both spatially resolved electronic processes and corresponding sample morphological characteristics. Here, we demonstrate an all-optical multimodal imaging approach that enables us to obtain both electronic excited-state and morphological information on a single optical microscope platform with simultaneous high temporal and spatial resolution. Specifically, images were acquired for the same region of interest in thin films of chloride containing mixed lead halide perovskites (CH 3 NH 3 PbI 3-x Cl x ) using femtosecond transient absorption, time-integrated photoluminescence, confocal reflectance, and transmission microscopies. Comprehensive image analysis revealed the presence of surface- and bulk-dominated contributions to the various images, which describe either spatially dependent electronic excited-state properties or morphological variations across the probed region of the thin films. These results show that PL probes effectively the species near or at the film surface.

Linking hygroscopicity and the surface microstructure of model inorganic salts, simple and complex carbohydrates, and authentic sea spray aerosol particles.

PubMed

Estillore, Armando D; Morris, Holly S; Or, Victor W; Lee, Hansol D; Alves, Michael R; Marciano, Meagan A; Laskina, Olga; Qin, Zhen; Tivanski, Alexei V; Grassian, Vicki H

2017-08-09

Individual airborne sea spray aerosol (SSA) particles show diversity in their morphologies and water uptake properties that are highly dependent on the biological, chemical, and physical processes within the sea subsurface and the sea surface microlayer. In this study, hygroscopicity data for model systems of organic compounds of marine origin mixed with NaCl are compared to data for authentic SSA samples collected in an ocean-atmosphere facility providing insights into the SSA particle growth, phase transitions and interactions with water vapor in the atmosphere. In particular, we combine single particle morphology analyses using atomic force microscopy (AFM) with hygroscopic growth measurements in order to provide important insights into particle hygroscopicity and the surface microstructure. For model systems, a range of simple and complex carbohydrates were studied including glucose, maltose, sucrose, laminarin, sodium alginate, and lipopolysaccharides. The measured hygroscopic growth was compared with predictions from the Extended-Aerosol Inorganics Model (E-AIM). It is shown here that the E-AIM model describes well the deliquescence transition and hygroscopic growth at low mass ratios but not as well for high ratios, most likely due to a high organic volume fraction. AFM imaging reveals that the equilibrium morphology of these single-component organic particles is amorphous. When NaCl is mixed with the organics, the particles adopt a core-shell morphology with a cubic NaCl core and the organics forming a shell similar to what is observed for the authentic SSA samples. The observation of such core-shell morphologies is found to be highly dependent on the salt to organic ratio and varies depending on the nature and solubility of the organic component. Additionally, single particle organic volume fraction AFM analysis of NaCl : glucose and NaCl : laminarin mixtures shows that the ratio of salt to organics in solution does not correspond exactly for individual particles - showing diversity within the ensemble of particles produced even for a simple two component system.

To What Extent is Primate Second Molar Enamel Occlusal Morphology Shaped by the Enamel-Dentine Junction?

PubMed Central

Gilissen, Emmanuel; Thiery, Ghislain

2015-01-01

The form of two hard tissues of the mammalian tooth, dentine and enamel, is the result of a combination of the phylogenetic inheritance of dental traits and the adaptive selection of these traits during evolution. Recent decades have been significant in unveiling developmental processes controlling tooth morphogenesis, dental variation and the origination of dental novelties. The enamel-dentine junction constitutes a precursor for the morphology of the outer enamel surface through growth of the enamel cap which may go along with the addition of original features. The relative contribution of these two tooth components to morphological variation and their respective response to natural selection is a major issue in paleoanthropology. This study will determine how much enamel morphology relies on the form of the enamel-dentine junction. The outer occlusal enamel surface and the enamel-dentine junction surface of 76 primate second upper molars are represented by polygonal meshes and investigated using tridimensional topometrical analysis. Quantitative criteria (elevation, inclination, orientation, curvature and occlusal patch count) are introduced to show that the enamel-dentine junction significantly constrains the topographical properties of the outer enamel surface. Our results show a significant correlation for elevation, orientation, inclination, curvature and occlusal complexity between the outer enamel surface and the enamel dentine junction for all studied primate taxa with the exception of four modern humans for curvature (p<0.05). Moreover, we show that, for all selected topometrical parameters apart from occlusal patch count, the recorded correlations significantly decrease along with enamel thickening in our sample. While preserving tooth integrity by providing resistance to wear and fractures, the variation of enamel thickness may modify the curvature present at the occlusal enamel surface in relation to enamel-dentine junction, potentially modifying dental functionalities such as blunt versus sharp dental tools. In terms of natural selection, there is a balance between increasing tooth resistance and maintaining efficient dental tools. In this sense the enamel cap acts as a functional buffer for the molar occlusal pattern. In primates, results suggest a primary emergence of dental novelties on the enamel-dentine junction and a secondary transposition of these novelties with no or minor modifications of dental functionalities by the enamel cap. Whereas enamel crenations have been reported by previous studies, our analysis do not support the presence of enamel tubercles without dentine relief nuclei. As is, the enamel cap is, at most, a secondary source of morphological novelty. PMID:26406597

Experimental investigation on photoelectric properties of ZAO thin film deposited on flexible substrate by magnetron sputtering

NASA Astrophysics Data System (ADS)

Hao, Ming; Liu, Kun; Liu, Xinghua; Wang, Dongyang; Ba, Dechun; Xie, Yuanhua; Du, Guangyu; Ba, Yaoshuai

2016-12-01

Transparent conductive ZAO (Zinc Aluminum Oxide) films on flexible substrates have a great potential for low-cost mass-production solar cells. ZAO thin films were achieved on flexible PET (polyethylene terephthalate) substrates by RF magnetron sputtering technology. The surface morphology and element content, the transmittance and the sheet resistance of the films were measured to determine the optical process parameters. The results show that the ZAO thin film shows the best parameters in terms of photoelectric performance including sputtering power, working pressure, sputtering time, substrate temperature (100 W, 1.5 Pa, 60 min, 125 °C). The sheet resistance of 510 Ω and transmittance in visible region of 92% were obtained after characterization. Surface morphology was uniform and compact with a good crystal grain.

Morphology effect on photocatalytic activity in Bi3Fe0.5Nb1.5O9.

PubMed

Yin, Xiaofeng; Li, Xiaoning; Gu, Wen; Zou, Wei; Liu, Huan; Zhu, Liuyang; Fu, Zhengping; Lu, Yalin

2018-06-29

In this work, the Aurivillius-phase ferroelectric Bi 3 Fe 0.5 Nb 1.5 O 9 were synthesized by hydrothermal (BFNO-H) and solid state methods (BFNO-S), respectively. The BFNO-H shows a hierarchical morphology, which is stacked by intersecting single-crystal nanosheets with {001} and {110} exposed facets, while the BFNO-S shows disorganized micron-scale morphology. BFNO-H shows a much stronger photodegradation activity (10.4 times and 9.8 times) than BFNO-S in the visible-light photodegradation of rhodamine B (RhB) and salicylic acid. The higher photodegradation activity of BFNO-H was firstly ascribed to the hierarchical structure and the larger specific surface area (16.586 m 2 g -1 ) because a large specific surface area can increase reactive sites and shorten photogenerated carrier migration distance. However, after being normalized by the specific surface area, BFNO-H still performs better than BFNO-S, implying that the specific surface area is not the only factor that determines the photocatalytic activity. Considering that the built-in electric field originating from spontaneous polarization in Bi 3 Fe 0.5 Nb 1.5 O 9 has existed in both ab plane and c direction, it matches well with the {001} and {110} exposed facets of BFNO-H nanosheets. This appropriate matching in BFNO-H nanosheets may improve the separation and transmission of photogenerated electron-hole pairs and further enhance its photocatalytic activity. Moreover, the trapping experiments reveals that holes (h + ) are the main active species and hole-derived oxidation is the main redox reaction during photodegradation of organic pollutions.

Morphology effect on photocatalytic activity in Bi3Fe0.5Nb1.5O9

NASA Astrophysics Data System (ADS)

Yin, Xiaofeng; Li, Xiaoning; Gu, Wen; Zou, Wei; Liu, Huan; Zhu, Liuyang; Fu, Zhengping; Lu, Yalin

2018-06-01

In this work, the Aurivillius-phase ferroelectric Bi3Fe0.5Nb1.5O9 were synthesized by hydrothermal (BFNO-H) and solid state methods (BFNO-S), respectively. The BFNO-H shows a hierarchical morphology, which is stacked by intersecting single-crystal nanosheets with {001} and {110} exposed facets, while the BFNO-S shows disorganized micron-scale morphology. BFNO-H shows a much stronger photodegradation activity (10.4 times and 9.8 times) than BFNO-S in the visible-light photodegradation of rhodamine B (RhB) and salicylic acid. The higher photodegradation activity of BFNO-H was firstly ascribed to the hierarchical structure and the larger specific surface area (16.586 m2 g‑1) because a large specific surface area can increase reactive sites and shorten photogenerated carrier migration distance. However, after being normalized by the specific surface area, BFNO-H still performs better than BFNO-S, implying that the specific surface area is not the only factor that determines the photocatalytic activity. Considering that the built-in electric field originating from spontaneous polarization in Bi3Fe0.5Nb1.5O9 has existed in both ab plane and c direction, it matches well with the {001} and {110} exposed facets of BFNO-H nanosheets. This appropriate matching in BFNO-H nanosheets may improve the separation and transmission of photogenerated electron–hole pairs and further enhance its photocatalytic activity. Moreover, the trapping experiments reveals that holes (h +) are the main active species and hole-derived oxidation is the main redox reaction during photodegradation of organic pollutions.

Catastrophic failure of contaminated fused silica optics at 355 nm

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

Genin, F. Y., LLNL

1996-12-03

For years, contamination has been known to degrade the performance of optics and to sometimes initiate laser-induced damage to initiate. This study has W to quantify these effects for fused silica windows used at 355 mm Contamination particles (Al, Cu, TiO{sub 2} and ZrO{sub 2}) were artificially deposited onto the surface and damage tests were conducted with a 3 ns NdYAG laser. The damage morphology was characterized by Nomarski optical microscopy. The results showed that the damage morphology for input and output surface contamination is different. For input surface contamination, both input and output surfaces can damage. In particular, themore » particle can induce pitting or drilling of the surface where the beam exits. Such damage usually grows catastrophically. Output surface contamination is usually ablated away on the shot but can also induce catastrophic damage. Plasmas are observed during illumination and seem to play an important role in the damage mechanism. The relationship between fluence and contamination size for which catastrophic damage occurred was plotted for different contamination materials. The results show that particles even as small as 10 {micro}m can substantially decrease the damage threshold of the window and that metallic particles on the input surface have a more negative effect than oxide particles.« less

A study of the solvent effect on the morphology of RDX crystal by molecular modeling method.

PubMed

Chen, Gang; Xia, Mingzhu; Lei, Wu; Wang, Fengyun; Gong, Xuedong

2013-12-01

Molecular dynamics simulations have been performed to investigate the effect of acetone solvent on the crystal morphology of RDX. The results show that the growth morphology of RDX crystal in vacuum is dominated by the (111), (020), (200), (002), and (210) faces using the BFDH laws, and (111) face is morphologically the most important. The analysis of surface structures of RDX crystal indicates that (020) face is non-polar, while (210), (111), (002), and (200) faces are polar among which (210) face has the strongest polarity. The interaction between acetone solvent and each RDX crystal face is different, and the order of binding energy on these surfaces is (210) > (111) > (002) > (200) > (020). The analysis of interactions among RDX and acetone molecules reveal that the system nonbond interactions are primary strong van der Waals and electrostatic interactions containing π-hole interactions, the weak hydrogen bond interactions are also existent. The effect of acetone on the growth of RDX crystal can be evaluated by comparing the binding energies of RDX crystalline faces. It can be predicted that compared to that in vacuum, in the process of RDX crystallization from acetone, the morphological importance of (210) face is increased more and (111) face is not the most important among RDX polar surfaces, while the non-polar (020) face probably disappears. The experimentally obtained RDX morphology grown from acetone is in agreement with the theoretical prediction.

Roller compaction: Effect of morphology and amorphous content of lactose powder on product quality.

PubMed

Omar, Chalak S; Dhenge, Ranjit M; Osborne, James D; Althaus, Tim O; Palzer, Stefan; Hounslow, Michael J; Salman, Agba D

2015-12-30

The effect of morphology and amorphous content, of three types of lactose, on the properties of ribbon produced using roller compaction was investigated. The three types of lactose powders were; anhydrous SuperTab21AN, α-lactose monohydrate 200 M, and spray dried lactose SuperTab11SD. The morphology of the primary particles was identified using scanning electron microscopy (SEM) and the powder amorphous content was quantified using NIR technique. SEM images showed that 21AN and SD are agglomerated type of lactose whereas the 200 M is a non-agglomerated type. During ribbon production, an online thermal imaging technique was used to monitor the surface temperature of the ribbon. It was found that the morphology and the amorphous content of lactose powders have significant effects on the roller compaction behaviour and on ribbon properties. The agglomerated types of lactose produced ribbon with higher surface temperature and tensile strength, larger fragment size, lower porosity and lesser fines percentages than the non-agglomerated type of lactose. The lactose powder with the highest amorphous content showed to result in a better binding ability between the primary particles. This type of lactose produced ribbons with the highest temperature and tensile strength, and the lowest porosity and amount of fines in the product. It also produced ribbon with more smooth surfaces in comparison to the other two types of lactose. It was noticed that there is a relationship between the surface temperature of the ribbon during production and the tensile strength of the ribbon; the higher the temperature of the ribbon during production the higher the tensile strength of the ribbon. Copyright © 2015 Elsevier B.V. All rights reserved.

The simple preparation of birnessite-type manganese oxide with flower-like microsphere morphology and its remarkable capacity retention

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

Zhu, Gang; Deng, Lingjuan; Wang, Jianfang

Graphical abstract: Flower-like birnessite-type manganese oxide microspheres with large specific surface area and excellent electrochemical properties have been prepared by a facile hydrothermal method. Highlights: ► Birnessite-type manganese oxide with flower-like microsphere morphology and large specific surface area. ► A facile low-temperature hydrothermal method. ► Novel flower-like microsphere consists of the thin nano-platelets. ► Birnessite-type manganese oxide exhibits an ideal capacitive behavior and excellent cycling stability. -- Abstract: Birnessite-type manganese oxide with flower-like microsphere morphology and large specific surface area has been prepared by hydrothermal treating a mixture solution of KMnO{sub 4} and (NH{sub 4}){sub 2}SO{sub 4} at 90 °Cmore » for 24 h. The obtained material is characterized by X-ray diffraction, scanning electron microscopy, transmission electron microscopy and N{sub 2} adsorption–desorption. Results indicate that the birnessite-type manganese oxide shows novel flower-like microsphere morphology and a specific surface area of 280 m{sup 2} g{sup −1}, and the flower-like microsphere consists of the thin nano-platelets. Electrochemical characterization indicates that the prepared material exhibits an ideal capacitive behavior with a capacitance value of 278 F g{sup −1} in 1 mol L{sup −1} Na{sub 2}SO{sub 4} aqueous solution at a scan rate of 5 mV s{sup −1}. Moreover, the prepared manganese oxide electrode shows excellent cycle stability, and the specific capacitance can maintain 98.6% of the initial one after 5000 cycles.« less

Differential Effects of Tissue Culture Coating Substrates on Prostate Cancer Cell Adherence, Morphology and Behavior

PubMed Central

Liberio, Michelle S.; Sadowski, Martin C.; Soekmadji, Carolina; Davis, Rohan A.; Nelson, Colleen C.

2014-01-01

Weak cell-surface adhesion of cell lines to tissue culture surfaces is a common problem and presents technical limitations to the design of experiments. To overcome this problem, various surface coating protocols have been developed. However, a comparative and precise real-time measurement of their impact on cell behavior has not been conducted. The prostate cancer cell line LNCaP, derived from a patient lymph node metastasis, is a commonly used model system in prostate cancer research. However, the cells’ characteristically weak attachment to the surface of tissue culture vessels and cover slips has impeded their manipulation and analysis and use in high throughput screening. To improve the adherence of LNCaP cells to the culture surface, we compared different coating reagents (poly-l-lysine, poly-l-ornithine, collagen type IV, fibronectin, and laminin) and culturing conditions and analyzed their impact on cell proliferation, adhesion, morphology, mobility and gene expression using real-time technologies. The results showed that fibronectin, poly-l-lysine and poly-l-ornithine improved LNCaP cells adherence and provoked cell morphology alterations, such as increase of nuclear and cellular area. These coating reagents also induced a higher expression of F-actin and reduced cell mobility. In contrast, laminin and collagen type IV did not improve adherence but promoted cell aggregation and affected cell morphology. Cells cultured in the presence of laminin displayed higher mobility than control cells. All the coating conditions significantly affected cell viability; however, they did not affect the expression of androgen receptor-regulated genes. Our comparative findings provide important insight for the selection of the ideal coating reagent and culture conditions for the cancer cell lines with respect to their effect on proliferation rate, attachment, morphology, migration, transcriptional response and cellular cytoskeleton arrangement. PMID:25375165

Particle self-assembly at ionic liquid-based interfaces.

PubMed

Frost, Denzil S; Nofen, Elizabeth M; Dai, Lenore L

2014-04-01

This review presents an overview of the nature of ionic liquid (IL)-based interfaces and self-assembled particle morphologies of IL-in-water, oil- and water-in-IL, and novel IL-in-IL Pickering emulsions with emphasis on their unique phenomena, by means of experimental and computational studies. In IL-in-water Pickering emulsions, particles formed monolayers at ionic liquid-water interfaces and were close-packed on fully covered emulsion droplets or aggregated on partially covered droplets. Interestingly, other than equilibrating at the ionic liquid-water interfaces, microparticles with certain surface chemistries were extracted into the ionic liquid phase with a high efficiency. These experimental findings were supported by potential of mean force calculations, which showed large energy drops as hydrophobic particles crossed the interface into the IL phase. In the oil- and water-in-IL Pickering emulsions, microparticles with acidic surface chemistries formed monolayer bridges between the internal phase droplets rather than residing at the oil/water-ionic liquid interfaces, a significant deviation from traditional Pickering emulsion morphology. Molecular dynamics simulations revealed aspects of the mechanism behind this bridging phenomenon, including the role of the droplet phase, surface chemistry, and inter-particle film. Novel IL-in-IL Pickering emulsions exhibited an array of self-assembled morphologies including the previously observed particle absorption and bridging phenomena. The appearance of these morphologies depended on the particle surface chemistry as well as the ILs used. The incorporation of particle self-assembly with ionic liquid science allows for new applications at the intersection of these two fields, and have the potential to be numerous due to the tunability of the ionic liquids and particles incorporated, as well as the particle morphology by combining certain groups of particle surface chemistry, IL type (protic or aprotic), and whether oil or water is incorporated. © 2013.

The effect of Pb addition on the morphology of CdSe quantum dot

NASA Astrophysics Data System (ADS)

Kim, Young-Kuk; Cho, Young-Sang; Chung, Kookchae; Choi, Chul-Jin

2010-08-01

CdSe quantum dots had been synthesized with a hot injection method. It was shown that the addition of Pb ions in the initial precursor solution changed the morphology of CdSe nanocrystals from slightly prolate ellipsoid to branched rod. Photoluminescence (PL) of the branched nanocrystals showed rapid depression of emission intensity due to the morphological development to the branched nanocrystal induced by Pb addition. Low temperature PL spectrum indicated that the surface recombination of charge carrier resulted in the large depression of emission from the branched nanocrystal.

Miscut dependent surface evolution in the process of N-polar GaN(000 1 bar) growth under N-rich condition

NASA Astrophysics Data System (ADS)

Krzyżewski, Filip; Załuska-Kotur, Magdalena A.; Turski, Henryk; Sawicka, Marta; Skierbiszewski, Czesław

2017-01-01

The evolution of surface morphology during the growth of N-polar (000 1 bar) GaN under N-rich conditions is studied by kinetic Monte Carlo (kMC) simulations for two substrates miscuts 2° and 4°. The results are compared with experimentally observed surface morphologies of (000 1 bar) GaN layers grown by plasma-assisted molecular beam epitaxy. The proposed kMC two-component model of GaN(000 1 bar) surface where both types of atoms, nitrogen and gallium, attach to the surface and diffuse independently shows that at relatively high rates of the step flow (miscut angle < 2 °) the low mobility of gallium adatoms causes surface instabilities and leads to experimentally observed roughening while for low rates of the step flow (miscut 4°), smooth surface can be obtained. In the presence of almost immobile nitrogen atoms under N-rich conditions crystal growth is realized by the process of two-dimensional island nucleation and coalescence. Larger crystal miscut, lower growth rate or higher temperature results in similar effect of the surface smoothening. We show that the surface also smoothens for the growth conditions with very high N-excess. In the presence of large number of nitrogen atoms the mobility of gallium atoms changes locally thus providing easier coalescence of separated island.

A comparative study of different bleaching agents on the morphology of human enamel: an in vitro SEM study.

PubMed

Uthappa, Roshan; Suprith, M L; Bhandary, Shreetha; Dash, Sumit

2012-11-01

The purpose of the study was to compare two different commercial bleaching agents, Opalescence with Colgate Platinum, and 30% phosphoric acid used as aggressive agent on the morphology of human enamel. Ten freshly extracted, noncarious, human maxillary central incisors extracted for periodontal reasons were used in this study. The labial surface of the disinfected teeth were polished using a polishing paste with the help of rubber cup and a slow speed handpiece. Each tooth was sectioned at cement-enamel junction and the crown was separated into four specimens, all taken from labial surface. Group 1 was treated with Colgate Platinum for 7 hours, group 2 with Opalescence for 7 hours, group 3 was treated with 30% phosphoric acid for 30 seconds and group 4 was untreated and used as control. After the treatment period, the specimens were washed with normal saline and stored in sterile bottle and sealed. Photomicrographs obtained from the scanning electron microscopy (SEM) after surface treatments were examined for no alteration, slight alteration, moderate alteration and severe alterations. The specimens treated with commercial bleaching agents revealed no enamel surface morphologic alterations compared to control group. The specimen treated with phosphoric acid showed severe alterations. Ten percent carbamide peroxide evaluated in this study does not etch tooth enamel or alter enamel surface morphology as do conventional etching techniques. Carbamine peroxide is a safe and effective tooth whitening agent even when used for extended period of time. The enamel surface remains smooth which reduces caries due to plaque collection.

Evaluation of PBS Treatment and PEI Coating Effects on Surface Morphology and Cellular Response of 3D-Printed Alginate Scaffolds.

PubMed

Mendoza García, María A; Izadifar, Mohammad; Chen, Xiongbiao

2017-11-01

Three-dimensional (3D) printing is an emerging technology for the fabrication of scaffolds to repair/replace damaged tissue/organs in tissue engineering. This paper presents our study on 3D printed alginate scaffolds treated with phosphate buffered saline (PBS) and polyethyleneimine (PEI) coating and their impacts on the surface morphology and cellular response of the printed scaffolds. In our study, sterile alginate was prepared by means of the freeze-drying method and then, used to prepare the hydrogel for 3D printing into calcium chloride, forming 3D scaffolds. Scaffolds were treated with PBS for a time period of two days and seven days, respectively, and PEI coating; then they were seeded with Schwann cells (RSC96) for the examination of cellular response (proliferation and differentiation). In addition, swelling and stiffness (Young's modulus) of the treated scaffolds was evaluated, while their surface morphology was assessed using scanning electron microscopy (SEM). SEM images revealed significant changes in scaffold surface morphology due to degradation caused by the PBS treatment over time. Our cell proliferation assessment over seven days showed that a two-day PBS treatment could be more effective than seven-day PBS treatment for improving cell attachment and elongation. While PEI coating of alginate scaffolds seemed to contribute to cell growth, Schwann cells stayed round on the surface of alginate over the period of cell culture. In conclusion, PBS-treatment may offer the potential to induce surface physical cues due to degradation of alginate, which could improve cell attachment post cell-seeding of 3D-printed alginate scaffolds.

Annealing induced low coercivity, nanocrystalline Co-Fe-Si thin films exhibiting inverse cosine angular variation

NASA Astrophysics Data System (ADS)

Hysen, T.; Al-Harthi, Salim; Al-Omari, I. A.; Geetha, P.; Lisha, R.; Ramanujan, R. V.; Sakthikumar, D.; Anantharaman, M. R.

2013-09-01

Co-Fe-Si based films exhibit high magnetic moments and are highly sought after for applications like soft under layers in perpendicular recording media to magneto-electro-mechanical sensor applications. In this work the effect of annealing on structural, morphological and magnetic properties of Co-Fe-Si thin films was investigated. Compositional analysis using X-ray photoelectron spectroscopy and secondary ion mass spectroscopy revealed a native oxide surface layer consisting of oxides of Co, Fe and Si on the surface. The morphology of the as deposited films shows mound like structures conforming to the Volmer-Weber growth model. Nanocrystallisation of amorphous films upon annealing was observed by glancing angle X-ray diffraction and transmission electron microscopy. The evolution of magnetic properties with annealing is explained using the Herzer model. Vibrating sample magnetometry measurements carried out at various angles from 0° to 90° to the applied magnetic field were employed to study the angular variation of coercivity. The angular variation fits the modified Kondorsky model. Interestingly, the coercivity evolution with annealing deduced from magneto-optical Kerr effect studies indicates a reverse trend compared to magetisation observed in the bulk. This can be attributed to a domain wall pinning at native oxide layer on the surface of thin films. The evolution of surface magnetic properties is correlated with morphology evolution probed using atomic force microscopy. The morphology as well as the presence of the native oxide layer dictates the surface magnetic properties and this is corroborated by the apparent difference in the bulk and surface magnetic properties.

Structure-to-property relationships in fuel cell catalyst supports: Correlation of surface chemistry and morphology with oxidation resistance of carbon blacks

NASA Astrophysics Data System (ADS)

Artyushkova, Kateryna; Pylypenko, Svitlana; Dowlapalli, Madhu; Atanassov, Plamen

2012-09-01

Linking durability of carbon blacks, expressed as their oxidation resistance, used in PEMFCs as catalyst supports, with their chemistry and morphology is an important task towards designing carbon blacks with desired properties. Structure-to-property relationship between surface chemistry determined by X-ray photoelectron spectroscopy (XPS), morphological structure determined by digital image processing of scanning electron microscopy (SEM) images, physical properties, and electrochemical corrosion behavior determined in an air-breathing gas-diffusion electrode is studied for several un-altered and several modified carbon blacks. We are showing that surface chemistry, graphitic content and certain physical characteristics such as Brunauer-Emmett-Teller (BET) surface area and pore volume, determined by nitrogen adsorptions are not sufficient to explain high corrosion instability of types of carbon blacks. Inclusion of morphological characteristics, such as roughness, texture and shape parameters provide for more inclusive description and therefore more complete structure-to-property correlations of corrosion behavior of carbon blacks. This paper presents the first direct statistically-derived structure-to-property relationship, developed by multivariate analysis (MVA) that links chemical and physical structural properties of the carbon blacks to their critical properties as supports for PEMFC catalysts. We have found that balance between electrocatalytic activity and high resistance towards oxidation and corrosion is achieved by balance between amount of graphitic content and surface oxide coverage, smaller overall roughness and, finally, larger amount of big elongated and loose, and, hypothetically, more hydrophobic pores.

Ultrastructural investigation of intact orbital implant surfaces using atomic force microscopy.

PubMed

Choi, Samjin; Lee, Seung Jun; Shin, Jae-Ho; Cheong, Youjin; Lee, Hui-Jae; Paek, Joo Hee; Kim, Jae Sik; Jin, Kyung-Hyun; Park, Hun-Kuk

2011-01-01

This study examined the surface nanostructures of three orbital implants: nonporous poly(methyl methacrylate) (PMMA), porous aluminum oxide and porous polyethylene. The morphological characteristics of the orbital implants surfaces were observed by atomic force microscopy (AFM). The AFM topography, phase shift and deflection images of the intact implant samples were obtained. The surface of the nonporous PMMA implant showed severe scratches and debris. The surface of the aluminum oxide implant showed a porous structure with varying densities and sizes. The PMMA implant showed nodule nanostructures, 215.56 ± 52.34 nm in size, and the aluminum oxide implant showed crystal structures, 730.22 ± 341.02 nm in size. The nonporous PMMA implant showed the lowest roughness compared with other implant biomaterials, followed by the porous aluminum oxide implant. The porous polyethylene implant showed the highest roughness and severe surface irregularities. Overall, the surface roughness of orbital implants might be associated with the rate of complications and cell adhesion. Copyright © 2011 Wiley Periodicals, Inc.

Correlation between surface morphology and surface forces of protein A adsorbed on mica.

PubMed Central

Ohnishi, S; Murata, M; Hato, M

1998-01-01

We have investigated the morphology and surface forces of protein A adsorbed on mica surface in the protein solutions of various concentrations. The force-distance curves, measured with a surface force apparatus (SFA), were interpreted in terms of two different regimens: a "large-distance" regimen in which an electrostatic double-layer force dominates, and an "adsorbed layer" regimen in which a force of steric origin dominates. To further clarify the forces of steric origin, the surface morphology of the adsorbed protein layer was investigated with an atomic force microscope (AFM) because the steric repulsive forces are strongly affected by the adsorption mode of protein A molecules on mica. At lower protein concentrations (2 ppm, 10 ppm), protein A molecules were adsorbed "side-on" parallel to the mica surfaces, forming a monolayer of approximately 2.5 nm. AFM images at higher concentrations (30 ppm, 100 ppm) showed protruding structures over the monolayer, which revealed that the adsorbed protein A molecules had one end oriented into the solution, with the remainder of each molecule adsorbed side-on to the mica surface. These extending ends of protein A overlapped each other and formed a "quasi-double layer" over the mica surface. These AFM images proved the existence of a monolayer of protein A molecules at low concentrations and a "quasi-double layer" with occasional protrusions at high concentrations, which were consistent with the adsorption mode observed in the force-distance curves. PMID:9449346

Surface morphology diagram for cylinder-forming block copolymer thin films.

PubMed

Zhang, Xiaohua; Berry, Brian C; Yager, Kevin G; Kim, Sangcheol; Jones, Ronald L; Satija, Sushil; Pickel, Deanna L; Douglas, Jack F; Karim, Alamgir

2008-11-25

We investigate the effect of the ordering temperature (T) and film thickness (h(f)) on the surface morphology of flow-coated block copolymer (BCP) films of asymmetric poly(styrene-block-methyl methacrylate). Morphology transitions observed on the ordered film surface by atomic force microscopy (AFM) are associated with a perpendicular to a parallel cylinder BCP microphase orientation transition with respect to the substrate with increasing h(f). "Hybrid" surface patterns for intermediate h(f) between these limiting morphologies are correspondingly interpreted by a coexistence of these two BCP microphase orientations so that two "transitional" h(f) exist for each T. This explanation of our surface patterns is supported by both neutron reflectivity and rotational SANS measurements. The transitional h(f) values as a function of T define upper and lower surface morphology transition lines, h(fu) (T) and h(fl) (T), respectively, and a surface morphology diagram that should be useful in materials fabrication. Surprisingly, the BCP film surface morphology depends on the method of film formation (flow-coated versus spun-cast films) so that nonequilibrium effects are evidently operative. This morphological variability is attributed primarily to the trapping of residual solvent (toluene) within the film (quantified by neutron reflectivity) due to film vitrification while drying. This effect has significant implications for controlling film structure in nanomanufacturing applications based on BCP templates.

Correlation between optical properties surface morphology of porous silicon electrodeposited by Fe3+ ion

NASA Astrophysics Data System (ADS)

Mabrouk, Asma; Lorrain, N.; Haji, M. L.; Oueslati, Meherzi

2015-01-01

In this paper, we analyze the photoluminescence spectra (PL) of porous silicon (PS) layer which is elaborated by electrochemical etching and passivated by Fe3+ ions (PSF) via current density, electro-deposition and temperature measurements. We observe unusual surface morphology of PSF surface and anomalous emission behavior. The PSF surface shows regular distribution of cracks, leaving isolated regions or ;platelets; of nearly uniform thickness. These cracks become more pronounced for high current densities. The temperature dependence of the PL peak energy (EPL) presents anomalous behaviors, i.e., the PL peak energy shows a successive red/blue/redshift (S-shaped behavior) with increasing temperature that we attribute to the existence of strong potential fluctuations induced by the electrochemical etching of PS layers. A competition process between localized and delocalized excitons is used to discuss these PL properties. In this case, the potential confinement plays a key role on the enhancement of PL intensity in PSF. To explain the temperature dependence of the PL intensity, we have proposed a recombination model based on the tunneling and dissociation of excitons.

Novel Gemini cationic surfactants as anti-corrosion for X-65 steel dissolution in oilfield produced water under sweet conditions: Combined experimental and computational investigations

NASA Astrophysics Data System (ADS)

Migahed, M. A.; elgendy, Amr.; EL-Rabiei, M. M.; Nady, H.; Zaki, E. G.

2018-05-01

Two new sequences of Gemini di-quaternary ammonium salts were synthesized characterized by FTIR and 1HNMR spectroscopic techniques and evaluated as corrosion inhibitor for X-65 steel dissolution in deep oil wells formation water saturated with CO2. The anti-corrosion performance of these compounds was studied by different electrochemical techniques i.e. (potentiodynamic polarization and AC impedance methods), Surface morphology (SEM and EDX) analysis and quantum chemical calculations. Results showed that the synthesized compounds were of mixed-type inhibitors and the inhibition capability was influenced by the inhibitor dose and the spacer substitution in their structure as indicated by Tafel plots. Surface active parameters were determined from the surface tension profile. The synthesized compounds adsorbed via Langmuir adsorption model with physiochemical adsorption as inferred from the standard free energy (ΔG°ads) values. Surface morphology (SEM and EDX) data for inhibitor (II) shows the development of adsorbed film on steel specimen. Finally, the experimental results were supported by the quantum chemical calculations using DFT theory.

Fe doped TiO2 nanofibers on the surface of graphene sheets for photovoltaics applications

NASA Astrophysics Data System (ADS)

Farhangi, Nasrin; Medina-Gonzalez, Yaocihuatl; Charpentier, Paul A.

2011-08-01

Highly ordered, visible light driven TiO2 nanowire arrays doped with Fe photocatalysts were grown on the surface of functionalized graphene sheets (FGSs) using a sol-gel method with titanium isopropoxide (TIP) monomer, acetic acid (HAc) as the polycondensation agent and iron chloride in the green solvent, supercritical carbon dioxide (scCO2). The morphology of the synthesized materials was studied by SEM and TEM, which showed uniform formation of Fe doped TiO2 nanofibers on the surface of graphene sheets, which acted as a template for nanowire growth through surface -COOH functionalities. Increasing Fe content in the nanowires did not change the morphology significantly. Optical properties of the synthesized composites were examined by UV spectroscopy which showed a significant reduction in band gap with increasing Fe content, i.e. 2.25 eV at 0.6% Fe. The enhancement of the optical properties of synthesized materials was confirmed by photocurrent measurement. The optimum sample containing 0.6% Fe doped TiO2 on the graphene sheets increased the power conversation efficiency by 6-fold in comparison to TiO2 alone.

Microhardness and morphological changes induced by Nd:Yag laser on dental enamel: an in vitro study.

PubMed

Bedini, Rossella; Manzon, Licia; Fratto, Giovanni; Pecci, Raffaella

2010-01-01

The aim of this work was a scanning electron microscopy (SEM) evaluation of the hardness and morphological changes of enamel irradiated by neodymium: yttrium aluminium garnet (Nd:YAG) laser with different energy levels. Twenty-eight human teeth samples were divided into 4 groups: control, where enamel surface was not lased, and 3 test treated with 3 different levels of energy power 0.6, 1.2 and 2.4 Watt, respectively. In each group, 5 samples underwent Vickers micro-hardness test and 2 samples were processed for SEM. No significant differences between treated and non treated samples were found by micro-hardness test. However, by SEM, test samples showed a rougher enamel surface than control. Specifically, the 0.6 Watt treated samples showed vertical scratches and glass-like areas, while in the other 2 groups enamel surface was covered by craters and cracks. These findings suggest that enamel should be lased at a low energy level to preserve its integrity and reduce demineralization, and thus for dental caries prevention purposes; while high energy level creates a retentive surface suitable for sealant or composite anchorage.

The Morphology of Silver Layers on SU8 polymers prepared by Electroless Deposition

NASA Astrophysics Data System (ADS)

Dutta, Aniruddha; Yuan, Biao; Heinrich, Helge; Grabill, Chris; Williams, Henry; Kuebler, Stephen; Bhattacharya, Aniket

2010-03-01

Silver was deposited onto the functionalized surface of polymeric SU-8 where gold nanoparticles (Au-NPs) act as nucleation sites using electroless metallization chemistry. Here we report on the evolution of the nanoscale morphology of deposited Ag studied by Transmission Electron Microscopy (TEM). In TEM of sample cross sections correlations between the original gold and the silver nanoparticles were obtained while plan-view TEM results showed the distribution of nanoparticles on the surface. Scanning TEM with a high-angle annular dark field detector was used to obtain atomic number contrast. The morphology of the deposited Ag was controlled through the presence and absence of gum Arabic. The thickness and height fluctuations of the Ag layer were determined as a function of time and a statistical analysis of the growth process was conducted for the initial deposition periods.

Effect of synthesis method on structure, band gap and surface morphology of delafossite oxides, CuAlO2 and CuFeO2

NASA Astrophysics Data System (ADS)

Shah, Aadil Abass; Azam, Ameer

2018-04-01

In this research work we have reported the synthesis of two different delafossites, CuAlO2 and CuFeO2 by two different synthesis methods viz hydrothermal method and the combustion method. The effect of synthesis on structure, band gap and morphology of the synthesized delafossites was carried out using various techniques. The phase and structure of the synthesized delafossites were studied and confirmed using X-ray diffraction and the crystallite size was calculated. FTIR measurements showed the presence of different stretching modes and functional groups in the synthesized oxides. The surface morphology was studied using the scanning electron microscopy. The band gap of the synthesized delafossite oxides was found to be in the range of 2.8 and 3.3 eV.

Automatic Brain Portion Segmentation From Magnetic Resonance Images of Head Scans Using Gray Scale Transformation and Morphological Operations.

PubMed

Somasundaram, Karuppanagounder; Ezhilarasan, Kamalanathan

2015-01-01

To develop an automatic skull stripping method for magnetic resonance imaging (MRI) of human head scans. The proposed method is based on gray scale transformation and morphological operations. The proposed method has been tested with 20 volumes of normal T1-weighted images taken from Internet Brain Segmentation Repository. Experimental results show that the proposed method gives better results than the popular skull stripping methods Brain Extraction Tool and Brain Surface Extractor. The average value of Jaccard and Dice coefficients are 0.93 and 0.962 respectively. In this article, we have proposed a novel skull stripping method using intensity transformation and morphological operations. This is a low computational complexity method but gives competitive or better results than that of the popular skull stripping methods Brain Surface Extractor and Brain Extraction Tool.

Synthesis and Characterization of Bionanoparticle-Silica Composites and Mesoporous Silica with Large Pores

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

Niu, Z.; Yang, L.; Kabisatpathy, S.

2009-03-24

A sol-gel process has been developed to incorporate bionanoparticles, such as turnip yellow mosaic virus, cowpea mosaic virus, tobacco mosaic virus, and ferritin into silica, while maintaining the integrity and morphology of the particles. The structures of the resulting materials were characterized by transmission electron microscopy, small angle X-ray scattering, and N{sub 2} adsorption-desorption analysis. The results show that the shape and surface morphology of the bionanoparticles are largely preserved after being embedded into silica. After removal of the bionanoparticles by calcination, mesoporous silica with monodisperse pores, having the shape and surface morphology of the bionanoparticles replicated inside the silica,more » was produced,. This study is expected to lead to both functional composite materials and mesoporous silica with structurally well-defined large pores.« less

Ion beam induced optical and surface modification in plasmonic nanostructures

NASA Astrophysics Data System (ADS)

Singh, Udai B.; Gautam, Subodh K.; Kumar, Sunil; Hooda, Sonu; Ojha, Sunil; Singh, Fouran

2016-07-01

In present work, ion irradiation induced nanostructuring has been exploited as an efficient and effective tool for synthesis of coupled plasmonics nanostructures by using 1.2 MeV Xe ions on Au/ZnO/Au system deposited on glass substrate. The results are correlated on the basis of their optical absorption, surface morphologies and enhanced sensitivity of evolved phonon modes by using UV Visible spectroscopy, scanning electron microscopy (SEM), and Raman spectroscopy (RS), respectively. Optical absorbance spectra of plasmonic nanostructures (NSs) show a decrease in band gap, which may be ascribed to the formation of defects with ion irradiation. The surface morphology reveals the formation of percolated NSs upon ion irradiation and Rutherford backscattering spectrometry (RBS) study clearly shows the formation of multilayer system. Furthermore, RS measurements on samples are studied to understand the enhanced sensitivity of ion irradiation induced phonon mode at 573 cm-1 along with other modes. As compared to pristine sample, a stronger and pronounced evolution of these phonon modes is observed with further ion irradiation, which indicates localized surface plasmon results with enhanced intensity of phonon modes of Zinc oxide (ZnO) material. Thus, such plasmonic NSs can be used as surface enhanced Raman scattering (SERS) substrates.

Insight of DFT and ab initio atomistic thermodynamics on the surface stability and morphology of In2O3

NASA Astrophysics Data System (ADS)

Zhang, Minhua; Wang, Wenyi; Chen, Yifei

2018-03-01

In2O3 catalysts show remarkable activity and selectivity in methanol synthesis from CO2 hydrogenation. In order to get insight into the surface stability of this catalyst, density functional theory and ab initio atomistic thermodynamics method were used to investigate the surface free energies of various facets as a function of oxygen chemical potential, as well as the influences of temperature, pressure and gas compositions. The results show that the (111) facet presents lowest surface free energy under oxygen-rich condition, while the indium-terminated (100) facet is the most stable one under oxygen-lean condition. Moreover, we applied Wulff construction to determine the equilibrium shape of In2O3 with different oxygen chemical potentials. The equilibrium shape under oxygen-lean condition is cubic, which only expose (100) facet, while, the equilibrium shape under oxygen-rich condition is octahedron, which only expose (111) facet. Meanwhile, the results agree well with what is observed experimentally. It is further predicted that Wulff shape of In2O3 exists in a truncated octahedron morphology in which the (100) surface becomes predominant plane under CO2 hydrogenation reaction conditions.

Surface modification to prevent oxide scale spallation

DOEpatents

Stephens, Elizabeth V; Sun, Xin; Liu, Wenning; Stevenson, Jeffry W; Surdoval, Wayne; Khaleel, Mohammad A

2013-07-16

A surface modification to prevent oxide scale spallation is disclosed. The surface modification includes a ferritic stainless steel substrate having a modified surface. A cross-section of the modified surface exhibits a periodic morphology. The periodic morphology does not exceed a critical buckling length, which is equivalent to the length of a wave attribute observed in the cross section periodic morphology. The modified surface can be created using at least one of the following processes: shot peening, surface blasting and surface grinding. A coating can be applied to the modified surface.

Interface layer to tailor the texture and surface morphology of Al-doped ZnO polycrystalline films on glass substrates

NASA Astrophysics Data System (ADS)

Nomoto, Junichi; Inaba, Katsuhiko; Kobayashi, Shintaro; Makino, Hisao; Yamamoto, Tetsuya

2017-06-01

A 10-nm-thick radio frequency magnetron-sputtered aluminum-doped zinc oxide (AZO) showing a texture with a preferential (0001) orientation on amorphous glass substrates was used as an interface layer for tailoring the orientation of 490-nm-thick polycrystalline AZO films subsequently deposited by direct current (DC) magnetron sputtering at a substrate temperature of 200 °C. Wide-angle X-ray diffraction pole figure analysis showed that the resulting 500-nm-thick AZO films showed a texture with a highly preferential c-axis orientation. This showed that DC-magnetron-sputtered AZO films grew along with the orientation matching that of the interface layer, whereas 500-nm-thick AZO films deposited on bare glass substrates by DC magnetron sputtering exhibited a mixed orientation of the c-plane and other planes. The surface morphology was also improved while retaining the lateral grain size by applying the interface layer as revealed by atomic force microscopy.

The surface stability and morphology of tobermorite 11 Å from first principles

NASA Astrophysics Data System (ADS)

Mutisya, Sylvia M.; Miranda, Caetano R.

2018-06-01

Tobermorite minerals are important in many industrial processes typically occurring in hydrous environment. Their functionality is therefore governed in various aspects by their morphology and surface stability/reactivity. Here, we present the results of the surface energies and morphology of normal tobermorite 11 Å in a water vapor environment investigated by employing first principles atomistic thermodynamic calculations. For the low index tobermorite surfaces studied, the calculated surface energies fall within a narrow range (0.41-0.97 J/m2) with the (0 0 4) surface being the most stable. The equilibrium morphology is a thin pseudohexagonal plate elongated along the b axis. The hydrated surfaces are more stable at high water vapor chemical potentials with the stability enhanced as the water partial pressures are varied from ambient to supercritical hydrothermal conditions. Increasing the water vapor chemical potential gives rise to a smaller size of the tobermorite crystal, with the equilibrium morphology remaining unaltered.

Effect of Water Vapor and Surface Morphology on the Low Temperature Response of Metal Oxide Semiconductor Gas Sensors

PubMed Central

Maier, Konrad; Helwig, Andreas; Müller, Gerhard; Hille, Pascal; Eickhoff, Martin

2015-01-01

In this work the low temperature response of metal oxide semiconductor gas sensors is analyzed. Important characteristics of this low-temperature response are a pronounced selectivity to acid- and base-forming gases and a large disparity of response and recovery time constants which often leads to an integrator-type of gas response. We show that this kind of sensor performance is related to the trend of semiconductor gas sensors to adsorb water vapor in multi-layer form and that this ability is sensitively influenced by the surface morphology. In particular we show that surface roughness in the nanometer range enhances desorption of water from multi-layer adsorbates, enabling them to respond more swiftly to changes in the ambient humidity. Further experiments reveal that reactive gases, such as NO2 and NH3, which are easily absorbed in the water adsorbate layers, are more easily exchanged across the liquid/air interface when the humidity in the ambient air is high. PMID:28793583

[Apatite-forming ability of pure titanium implant after micro-arc oxidation treatment].

PubMed

Tian, Zhihui; Zhang, Yu; Wang, Lichao; Nan, Kaihui

2013-10-01

To investigate the apatite forming ability of pure titanium implant after micro-arc oxidation treatment in simulated body fluid (SBF) and obtain implants with calcium phosphate (Ca-P) layers. The implants were immersed in (SBF) after micro-arc oxidation treatment for different time lengths, and their apatite forming ability and the morphology and constituents of the Ca-P layers formed on the sample surface were analyzed using X-ray diffraction, scanning electron microscopy, X-ray photoelectron spectroscopy, and energy dispersive electron probe. After immersion in SBF, large quantities of Ca-P layers were induced on the surface of the samples. The Ca-P layers were composed of octacalcium phosphate and carbonated hydroxyapatite, and the crystals showed a plate-like morphology with an oriented growth. The implants with micro-arc oxidation treatment show good apatite forming ability on the surface with rich calcium and phosphorus elements. The formed layers are composed of bone-like apatite including octacalcium phosphate and carbonated hydroxyapatite.

Nanostructured medical device coatings based on self-assembled poly(lactic-co-glycolic acid) nanoparticles.

PubMed

Dayyoub, Eyas; Hobler, Christian; Nonnweiler, Pierina; Keusgen, Michael; Bakowsky, Udo

2013-07-01

Here we present a new method for providing nanostructured drug-loaded polymer films which enable control of film surface morphology and delivery of therapeutic agents. Silicon wafers were employed as models for implanted biomaterials and poly(lactic-co-glycolic acid) (PLGA) nanoparticles were assembled onto the silicon surface by electrostatic interaction. Monolayers of the PLGA particles were deposited onto the silicon surface upon incubation in an aqueous particle suspension. Particle density and surface coverage of the silicon wafers were varied by altering particle concentration, incubation time in nanoparticle suspension and ionic strength of the suspension. Dye loaded nanoparticles were prepared and assembled to silicon surface to form nanoparticle films. Fluorescence intensity measurements showed diffusion-controlled release of the dye over two weeks and atomic force microscopy (AFM) analysis revealed that these particles remained attached to the surface during the incubation time. This work suggests that coating implants with PLGA nanoparticles is a versatile technique which allows drug release from the implant surface and modulation of surface morphology. Copyright © 2013 Elsevier B.V. All rights reserved.

Atomic force microscopy analysis of different surface treatments of Ti dental implant surfaces

NASA Astrophysics Data System (ADS)

Bathomarco, Ti R. V.; Solorzano, G.; Elias, C. N.; Prioli, R.

2004-06-01

The surface of commercial unalloyed titanium, used in dental implants, was analyzed by atomic force microscopy. The morphology, roughness, and surface area of the samples, submitted to mechanically-induced erosion, chemical etching and a combination of both, were compared. The results show that surface treatments strongly influence the dental implant physical and chemical properties. An analysis of the length dependence of the implant surface roughness shows that, for scan sizes larger than 50 μm, the average surface roughness is independent of the scanning length and that the surface treatments lead to average surface roughness in the range of 0.37 up to 0.48 μm. It is shown that the implant surface energy is sensitive to the titanium surface area. As the area increases there is a decrease in the surface contact angle.

Simple chemical synthesis of novel ZnO nanostructures: Role of counter ions

NASA Astrophysics Data System (ADS)

Pudukudy, Manoj; Yaakob, Zahira

2014-04-01

This article reports the synthesis, characterisation and photocatalytic activity of novel ZnO nanostructures prepared via the thermal decomposition of hydrozincite. Hydrozincites were obtained by the conventional precipitation route using different zinc salts such as acetate, nitrate, chloride and sulphate. The effect of counter ions (CH3COO-, Cl-, NO3-, and SO42-) on the structural, textural, morphological and optical properties was investigated. Various characterisations depicted the active role of counter ions in the properties of ZnO. Hexagonal wurtzite structure of ZnO with fine crystalline size was obvious from the XRD results, irrespective of the counter ions. Electron microscopic images indicated the role of counter ions in the surface and internal morphology of ZnO nanomaterials. Special coral like agglomerated morphology of elongated particles with high porosity was observed for the ZnO prepared from acetate precursor. Spherical, elongated and irregular shaped bigger lumps of ZnO nanoparticles with various novel morphologies were resulted for the sulphate, nitrate and chloride precursors respectively. Highly ordered porous micro disc like morphology was noted for the ZnO samples prepared from the sulphate and nitrate salts. Photoluminescence spectra showed the characteristic blue and green emission bands, depicting the presence of large crystal defects and high oxygen vacancies in the samples. Photocatalytic activity of the as-prepared ZnO catalysts was examined by the degradation of methylene blue under UV light irradiation. Degradation results indicated their substantial activity with respect to the counter ions. ZnO prepared from the acetate precursor showed highest photoactivity due to its high surface area, special morphology and high oxygen vacancies.

The effect of different chemical agents on human enamel: an atomic force and scanning electron microscopy study

NASA Astrophysics Data System (ADS)

Rominu, Roxana O.; Rominu, Mihai; Negrutiu, Meda Lavinia; Sinescu, Cosmin; Pop, Daniela; Petrescu, Emanuela

2010-12-01

PURPOSE: The goal of our study was to investigate the changes in enamel surface roughess induced by the application of different chemical substances by atomic force microscopy and scanning electron microscopy. METHOD: Five sound human first upper premolar teeth were chosen for the study. The buccal surface of each tooth was treated with a different chemical agent as follows: Sample 1 - 38% phosphoric acid etching (30s) , sample 2 - no surface treatment (control sample), 3 - bleaching with 37.5 % hydrogen peroxide (according to the manufacturer's instructions), 4 - conditioning with a self-etching primer (15 s), 5 - 9.6 % hydrofluoric acid etching (30s). All samples were investigated by atomic force microscopy in a non-contact mode and by scanning electron microscopy. Several images were obtained for each sample, showing evident differences regarding enamel surface morphology. The mean surface roughness and the mean square roughness were calculated and compared. RESULTS: All chemical substances led to an increased surface roughness. Phosphoric acid led to the highest roughness while the control sample showed the lowest. Hydrofluoric acid also led to an increase in surface roughness but its effects have yet to be investigated due to its potential toxicity. CONCLUSIONS: By treating the human enamel with the above mentioned chemical compounds a negative microretentive surface is obtained, with a morphology depending on the applied substance.

A comparative study of the influence of alpha-lactose monohydrate particle morphology on granule and tablet properties after roll compaction/dry granulation.

PubMed

Grote, Simon; Kleinebudde, Peter

2018-05-29

The influence of particle morphology and size of alpha-lactose monohydrate on dry granules and tablets was studied. Four different morphologies were investigated: Two grades of primary crystals, which differed in their particle size and structure (compact crystals vs. agglomerates). The materials were roll compacted at different specific compaction forces and changes in the particle size distribution and the specific surface area were measured. Afterwards, two fractions of granules were pressed to tablets and the tensile strength was compared to that from tablets compressed from the raw materials. The specific surface area was increased induced by roll compaction/dry granulation for all materials. At increased specific compaction forces, the materials showed sufficient size enlargement. The morphology of lactose determined the strength of direct compressed tablets. In contrast, the strength of granule tablets was leveled by the previous compression step during roll compaction/dry granulation. Thus, the tensile strength of tablets compressed directly from the powder mixtures determined whether materials exhibited a loss in tabletability after roll compaction/dry granulation or not. The granule size had only a slight influence on the strength of produced tablets. In some cases, the fraction of smaller granules showed a higher tensile strength compared to the larger fraction.

Preparation and characterization of microporous poly(d,l-lactic acid) film for tissue engineering scaffold

PubMed Central

Shi, Shuai; Wang, Xiu Hong; Guo, Gang; Fan, Min; Huang, Mei Juan; Qian, Zhi Yong

2010-01-01

We prepared a series of microporous films based on poly(d,l-lactic acid) (PLA) via phase separation. According to scanning electron microscopy (SEM), a 3-dimensional foamy structure with multimicrometer scale pores on the air surface of film could be observed. As the morphology of PLA film could not be stabilized using solvent–nonsolvent phase separation, we investigated the effect of temperature, air movement, and concentration on the properties of microporous PLA films. The results show that when the temperature was 25°C in a vacuum, it was easy to prepare PLA film with micropores, and it was stable. As the relationship between the morphology and formation factors was clear and the morphology of the PLA film was controllable, we studied the PLA film’s potential use for cell culture. SEM results showed that NIH3T3 cell could be adhered on the surface of film well after incubation for 2 days. Meanwhile, in vitro culture experiments revealed the great biocompatibility of the scaffold for adsorption and proliferation of fibroblasts. PMID:21179227

Adsorbate-driven morphological changes on Cu(111) nano-pits

DOE PAGES

Mudiyanselage, K.; Xu, F.; Hoffmann, F. M.; ...

2014-12-09

Adsorbate-driven morphological changes of pitted-Cu(111) surfaces have been investigated following the adsorption and desorption of CO and H. The morphology of the pitted-Cu(111) surfaces, prepared by Ar + sputtering, exposed a few atomic layers deep nested hexagonal pits of diameters from 8 to 38 nm with steep step bundles. The roughness of pitted-Cu(111) surfaces can be healed by heating to 450-500 K in vacuum. Adsorption of CO on the pitted-Cu(111) surface leads to two infrared peaks at 2089-2090 and 2101-2105 cm -1 for CO adsorbed on under-coordinated sites in addition to the peak at 2071 cm -1 for CO adsorbedmore » on atop sites of the close-packed Cu(111) surface. CO adsorbed on under-coordinated sites is thermally more stable than that of atop Cu(111) sites. Annealing of the CO-covered surface from 100 to 300 K leads to minor changes of the surface morphology. In contrast, annealing of a H covered surface to 300 K creates a smooth Cu(111) surface as deduced from infrared data of adsorbed CO and scanning tunnelling microscopy (STM) imaging. The observation of significant adsorbate-driven morphological changes with H is attributed to its stronger modification of the Cu(111) surface by the formation of a sub-surface hydride with a hexagonal structure, which relaxes into the healed Cu(111) surface upon hydrogen desorption. These morphological changes occur ~150 K below the temperature required for healing of the pitted-Cu(111) surface by annealing in vacuum. In contrast, the adsorption of CO, which only interacts with the top-most Cu layer and desorbs by 160 K, does not significantly change the morphology of the pitted-Cu(111) surface.« less

The effects of argon ion bombardment on the corrosion resistance of tantalum

NASA Astrophysics Data System (ADS)

Ramezani, A. H.; Sari, A. H.; Shokouhy, A.

2017-02-01

Application of ion beam has been widely used as a surface modification method to improve surface properties. This paper investigates the effect of argon ion implantation on surface structure as well as resistance against tantalum corrosion. In this experiment, argon ions with energy of 30 keV and in doses of 1 × 1017-10 × 1017 ions/cm2 were used. The surface bombardment with inert gases mainly produces modified topography and morphology of the surface. Atomic Force Microscopy was also used to patterned the roughness variations prior to and after the implantation phase. Additionally, the corrosion investigation apparatus wear was applied to compare resistance against tantalum corrosion both before and after ion implantation. The results show that argon ion implantation has a substantial impact on increasing resistance against tantalum corrosion. After the corrosion test, scanning electron microscopy (SEM) analyzed the samples' surface morphologies. In addition, the elemental composition is characterized by energy-dispersive X-ray (EDX) analysis. The purpose of this paper was to obtain the perfect condition for the formation of tantalum corrosion resistance. In order to evaluate the effect of the ion implantation on the corrosion behavior, potentiodynamic tests were performed. The results show that the corrosion resistance of the samples strongly depends on the implantation doses.

Hierarchically porous carbon/polyaniline hybrid for use in supercapacitors.

PubMed

Joo, Min Jae; Yun, Young Soo; Jin, Hyoung-Joon

2014-12-01

A hierarchically porous carbon (HPC)/polyaniline (PANI) hybrid electrode was prepared by the polymerization of PANI on the surface of the HPC via rapid-mixing polymerization. The surface morphologies and chemical composition of the HPC/PANI hybrid electrode were characterized using transmission electron microscopy and X-ray photoelectron spectroscopy (XPS), respectively. The surface morphologies and XPS results for the HPC, PANI and HPC/PANI hybrids indicate that PANI is coated on the surface of HPC in the HPC/PANI hybrids which have two different nitrogen groups as a benzenoid amine (-NH-) peak and positively charged nitrogen (N+) peak. The electrochemical performances of the HPC/PANI hybrids were analyzed by performing cyclic voltammetry and galvanostatic charge-discharge tests. The HPC/PANI hybrids showed a better specific capacitance (222 F/g) than HPC (111 F/g) because of effect of pseudocapacitor behavior. In addition, good cycle stabilities were maintained over 1000 cycles.

Chemical and morphological characteristics of lithium electrode surfaces

NASA Technical Reports Server (NTRS)

Yen, S. P. S.; Shen, D.; Vasquez, R. P.; Grunthaner, F. J.; Somoano, R. B.

1981-01-01

Lithium electrode surfaces were analyzed for chemical and morphological characteristics, using electron spectroscopy chemical analysis (ESCA) and scanning electron microscopy (SEM). Samples included lithium metal and lithium electrodes which were cycled in a 1.5 M lithium arsenic hexafluoride/two-methyl tetrahydrofuran electrolyte. Results show that the surface of the as-received lithium metal was already covered by a film composed of LiO2 and an Li2O/CO2 adduct with a thickness of approximately 100-200 A. No evidence of Ni3 was found. Upon exposure of the lithium electrode to a 1.5 M LiAsF6/2-Me-THF electrochemical environment, a second film was observed to form on the surface, consisting primarily of As, Si, and F, possibly in the form of lithium arsenic oxyfluorides or lithium fluorosilicates. It is suggested that the film formation may be attributed to salt degradation.

Morphology variation, composition alteration and microstructure changes in ion-irradiated 1060 aluminum alloy

NASA Astrophysics Data System (ADS)

Wan, Hao; Si, Naichao; Wang, Quan; Zhao, Zhenjiang

2018-02-01

Morphology variation, composition alteration and microstructure changes in 1060 aluminum irradiated with 50 keV helium ions were characterized by field emission scanning electron microscopy (FESEM) equipped with x-ray elemental scanning, 3D measuring laser microscope and transmission electron microscope (TEM). The results show that, helium ions irradiation induced surface damage and Si-rich aggregates in the surfaces of irradiated samples. Increasing the dose of irradiation, more damages and Si-rich aggregates would be produced. Besides, defects such as dislocations, dislocation loops and dislocation walls were the primary defects in the ion implanted layer. The forming of surface damages were related with preferentially sputtering of Al component. While irradiation-enhanced diffusion and irradiation-induced segregation resulted in the aggregation of impurity atoms. And the aggregation ability of impurity atoms were discussed based on the atomic radius, displacement energy, lattice binding energy and surface binding energy.

Ablation of gold irradiated by femtosecond laser pulse: Experiment and modeling

NASA Astrophysics Data System (ADS)

Ashitkov, S. I.; Komarov, P. S.; Zhakhovsky, V. V.; Petrov, Yu V.; Khokhlov, V. A.; Yurkevich, A. A.; Ilnitsky, D. K.; Inogamov, N. A.; Agranat, M. B.

2016-11-01

We report on the ablation phenomena in gold sample irradiated by femtosecond laser pulses of moderate intensity. Dynamics of optical constants and expansion of a heated surface layer was investigated in a range from picosecond up to subnanosecond using ultrafast interferometry. Also morphology of the ablation craters and value of an ablation threshold (for absorbed fluence) were measured. The experimental data are compared with simulations of mass flows obtained by two-temperature hydrodynamics and molecular dynamics methods. Simulation shows evolution of a thin surface layer pressurized by a laser pulse. Unloading of the pressurized layer proceeds together with electron-ion thermalization, melting, cavitation and spallation of a part of surface liquid layer. The experimental and simulation results on two-temperature physics and on a fracture, surface morphology and strength of liquid gold at a strain rate ∼ 109 s-1 are discussed.

Two-dimensional and three-dimensional evaluation of the deformation relief

NASA Astrophysics Data System (ADS)

Alfyorova, E. A.; Lychagin, D. V.

2017-12-01

This work presents the experimental results concerning the research of the morphology of the face-centered cubic single crystal surface after compression deformation. Our aim is to identify the method of forming a quasiperiodic profile of single crystals with different crystal geometrical orientation and quantitative description of deformation structures. A set of modern methods such as optical and confocal microscopy is applied to determine the morphology of surface parameters. The results show that octahedral slip is an integral part of the formation of the quasiperiodic profile surface starting with initial strain. The similarity of the formation process of the surface profile at different scale levels is given. The size of consistent deformation regions is found. This is 45 µm for slip lines ([001]-single crystal) and 30 µm for mesobands ([110]-single crystal). The possibility of using two- and three-dimensional roughness parameters to describe the deformation structures was shown.

Evaluation of primary tooth enamel surface morphology and microhardness after Nd:YAG laser irradiation and APF gel treatment--an in vitro study.

PubMed

Banda, Naveen Reddy; Vanaja Reddy, G; Shashikiran, N D

2011-01-01

Laser irradiation and fluoride has been used as a preventive tool to combat dental caries in permanent teeth, but little has been done for primary teeth which are more prone to caries. The purpose of this study was to evaluate microhardness alterations in the primary tooth enamel after Nd-YAG laser irradiation alone and combined with topical fluoride treatment either before or after Nd-YAG laser irradiation. Ten primary molars were sectioned and assigned randomly to: control group, Nd-YAG laser irradiation, Nd-YAG lasing before APF and APF followed by Nd-YAG lasing. The groups were evaluated for microhardness. Surface morphological changes were observed using SEM. Statistical comparisons were performed. The control group's SEM showed a relatively smooth enamel surface and lasing group had fine cracks and porosities. In the lasing + fluoride group a homogenous confluent surface was seen. In the fluoride + lasing group an irregular contour with marked crack propagation was noted. There was a significant increase in the microhardness of the treatment groups. Nd-YAG laser irradiation and combined APF treatment of the primary tooth enamel gave morphologically hardened enamel surface which can be a protective barrier against a cariogenic attack.

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

Pariona, Moises Meza, E-mail: mmpariona@uepg.br; Teleginski, Viviane; Santos, Kelly dos

Laser beam welding has recently been incorporated into the fabrication process of aircraft and automobile structures. Surface roughness is an important parameter of product quality that strongly affects the performance of mechanical parts, as well as production costs. This parameter influences the mechanical properties such as fatigue behavior, corrosion resistance, creep life, etc., and other functional characteristics such as friction, wear, light reflection, heat transmission, lubrification, electrical conductivity, etc. The effects of laser surface remelting (LSR) on the morphology of Al-Fe aerospace alloys were examined before and after surface treatments, using optical microscopy (OM), scanning electron microscopy (SEM), low-angle X-raymore » diffraction (LA-XRD), atomic force microscopy (AFM), microhardness measurements (Vickers hardness), and cyclic voltammetry. This analysis was performed on both laser-treated and untreated sanded surfaces, revealing significant differences. The LA-XRD analysis revealed the presence of alumina, simple metals and metastable intermetallic phases, which considerably improved the microhardness of laser-remelted surfaces. The morphology produced by laser surface remelting enhanced the microstructure of the Al-Fe alloys by reducing their roughness and increasing their hardness. The treated surfaces showed passivity and stability characteristics in the electrolytic medium employed in this study. - Highlights: Black-Right-Pointing-Pointer The samples laser-treated and untreated showed significant differences. Black-Right-Pointing-Pointer The La-XRD revealed the presence of alumina in Al-1.5 wt.% Fe. Black-Right-Pointing-Pointer The laser-treated reducing the roughness and increasing the hardness. Black-Right-Pointing-Pointer The laser-treated surfaces showed characteristic passive in the electrolytic medium. Black-Right-Pointing-Pointer The laser-treated is a promising technique for applications technological.« less

Surface morphology of molybdenum silicide films upon low-energy ion beam sputtering.

PubMed

Gago, R; Jaafar, M; Palomares, F J

2018-07-04

The surface morphology of molybdenum silicide (Mo x Si 1-x ) films has been studied after low-energy Ar + ion beam sputtering (IBS) to explore eventual pattern formation on compound targets and, simultaneously, gather information about the mechanisms behind silicide-assisted nanopatterning of silicon surfaces by IBS. For this purpose, Mo x Si 1-x films with compositions below, equal and above the MoSi 2 stoichiometry (x  =  0.33) have been produced by magnetron sputtering, as assessed by Rutherford backscattering spectrometry (RBS). The surface morphology of silicon and silicide films before and after IBS has been imaged by atomic force microscopy (AFM), comprising conditions where typical nanodot or ripple patterns emerge on the former. In the case of irradiated Mo x Si 1-x surfaces, AFM shows a marked surface smoothing at normal incidence with and without additional Mo incorporation (the former results in nanodot patterns on Si). The morphological analysis also provides no evidence of ion-induced phase separation in irradiated Mo x Si 1-x . Contrary to silicon, Mo x Si 1-x surfaces also do not display ripple formation for (impurity free) oblique irradiations, except at grazing incidence conditions where parallel ripples emerge in a more evident fashion than in the Si counterpart. By means of RBS, irradiated Mo x Si 1-x films with 1 keV Ar + at normal incidence have also been used to measure experimentally the (absolute) sputtering yield and rate of Si and Mo x Si 1-x materials. The analysis reveals that, under the present working conditions, the erosion rate of silicides is larger than for silicon, supporting simulations from the TRIDYN code. This finding questions the shielding effect from silicide regions as roughening mechanism in metal-assisted nanopatterning of silicon. On the contrary, the results highlight the relevance of in situ silicide formation. Ripple formation on Mo x Si 1-x under grazing incidence is also attributed to the dominance of sputtering effects under this geometry. In conclusion, our work provides some insights into the complex morphological evolution of compound surfaces and solid experimental evidences regarding the mechanisms behind silicide-assisted nanopatterning.

Combinatorial growth of oxide nanoscaffolds and its influence in osteoblast cell adhesion

NASA Astrophysics Data System (ADS)

Acevedo-Morantes, Claudia Y.; Irizarry-Ortiz, Roberto A.; Caceres-Valencia, Pablo G.; Singh, Surinder P.; Ramirez-Vick, Jaime E.

2012-05-01

We report a novel method for high-throughput investigations on cell-material interactions based on metal oxide nanoscaffolds. These scaffolds possess a continuous gradient of various titanium alloys allowing the compositional and morphological variation that could substantially improve the formation of an osseointegrative interface with bone. The model nanoscaffold has been fabricated on commercially pure titanium (cp-Ti) substrate with a compositional gradients of tin (Sn), chromium (Cr), and niobium (Nb) deposited using a combinatorial approach followed by annealing to create native oxide surface. As an invitro test system, the human fetal osteoblastic cell line (hFOB 1.19) has been used. Cell-adhesion of hFOB 1.19 cells and the suitability of these alloys have been evaluated for cell-morphology, cell-number, and protein adsorption. Although, cell-morphology was not affected by surface composition, cell-proliferation rates varied significantly with surface metal oxide composition; with the Sn- and Nb-rich regions showing the highest proliferation rate and the Cr-rich regions presenting the lowest. The results suggest that Sn and Nb rich regions on surface seems to promote hFOB 1.19 cell proliferation and may therefore be considered as implant material candidates that deserve further analysis.

The lateral In2O3 nanowires and pyramid networks manipulation by controlled substrate surface energy in annealing evolution

NASA Astrophysics Data System (ADS)

Shariati, Mohsen; Darjani, Mojtaba

2016-02-01

The continuous laterally aligned growth of In2O3 nanocrystal networks extended with nanowire and pyramid connections under annealing influence has been reported. These nanostructures have been grown on Si substrate by using oxygen-assisted annealing process through PVD growth technique. The formation of In2O3 nanocrystals has been achieved by the successive growth of critical self-nucleated condensation in three orientations. The preferred direction was the route between two pyramids especially in the smallest surface energy. The effects of substrate temperature in annealing process on the morphological properties of the as-grown nanostructures were investigated. The annealing technique showed that by controlling the surface energy, the morphology of structures was changed from unregulated array to defined nanostructures; especially nanowires 50 nm in width. The obtained nanostructures also were investigated by the (transmission electron microscopy) TEM, Raman spectrum and the (X-ray diffraction) XRD patterns. They indicated that the self-assembled In2O3 nanocrystal networks have been fabricated by the vapor-solid (VS) growth mechanism. The growth mechanism process was prompted to attribute the relationship among the kinetics parameters, surface diffusion and morphology of nanostructures.

Structural changes of anodic layer on titanium in sulfate solution as a function of anodization duration in constant current mode

NASA Astrophysics Data System (ADS)

Komiya, Shinji; Sakamoto, Kouta; Ohtsu, Naofumi

2014-03-01

The present study investigated the effect of anodization time, in constant current mode, on the anodic oxide layer formed on titanium (Ti). Anodization of the Ti substrate was　carried out in a 0.1 M (NH4)2SO4 aqueous solution with reaction times of various durations, after which the characteristics and photocatalytic activity were investigated in detail. The TiO2 layer fabricated in a short duration exhibited comparatively flat surface morphology and an anatase-type crystal structure. This layer acted as a photocatalyst only under ultraviolet light (UV) illumination. Upon prolonging the anodization, the layer structure changed drastically. The surface morphology became rough, and the crystal structure changed to rutile-type TiO2. Furthermore, the layer showed photocatalytic activity both under UV and visible light illumination. Further anodization increased the amount of methylene blue (MB) adsorbed on the surface, but did not cause additional change to the structure of the anodic layer. The surface morphology and crystal structure of the anodic layer were predominantly controlled by the anodization time; thus, the anodization time is an important parameter for controlling the characteristics of the anodic layer.

Effects of hydroxyapatite/Zr and bioglass/Zr coatings on morphology and corrosion behaviour of Rex-734 alloy.

PubMed

Say, Y; Aksakal, B

2016-06-01

To improve corrosion resistance of metallic implant surfaces, Rex-734 alloy was coated with two different bio-ceramics; single-Hydroxyapatite (HA), double-HA/Zirconia(Zr) and double-Bioglass (BG)/Zr by using sol-gel method. Porous surface morphologies at low crack density were obtained after coating and sintering processes. Corrosion characteristics of coatings were determined by Open circuit potential and Potentiodynamic polarization measurements during corrosion tests. Hardness and adhesion strength of coating layers were measured and their surface morphologies before and after corrosion were characterized by scanning electron microscope (SEM), XRD and EDX. Through the SEM analysis, it was observed that corrosion caused degradation and sphere-like formations appeared with dimples on the coated surfaces. The coated substrates that exhibit high crack density, the corrosion was more effective by disturbing and transmitting through the coating layer, produced CrO3 and Cr3O8 oxide formation. It was found that the addition of Zr provided an increase in adhesion strength and corrosion resistance of the coatings. However, BG/Zr coatings had lower adhesion strength than the HA/Zr coatings, but showed higher corrosion resistance.

Effects of helium ion implantation on the surface morphology of tungsten at high temperature for the first wall armor and divertor plates of fusion reactors

NASA Astrophysics Data System (ADS)

Zenobia, Samuel J.

Three devices at the University of Wisconsin-Madison Inertial Electrostatic Confinement (UW IEC) laboratory were used to implant W and W alloys with helium ions at high temperatures. These devices were HOMER, HELIOS, and the Materials Irradiation Experiment (MITE-E). The research presented in this thesis will focus on the experiments carried out utilizing the MITE-E. Early UW work in HOMER and HELIOS on silicon carbide, carbon velvet, W-coated carbon velvet, fine-grain W, nano-grain W, W needles, and single- and polycrystalline W showed that these materials were not resistant to He+ implantation above ˜800 °C. Unalloyed W developed a "coral-like" surface morphology after He+ implantation, but appeared to be the most robust material investigated. The MITE-E used an ion gun technology to implant tungsten with 30 keV He+. Tungsten specimens were implanted at 900 °C to total average fluences of 6x1016 -- 6x1018 He +/cm2. Other specimens were implanted to a total average fluence of 5x1018 He+/cm2 at temperatures between 500 and 900 °C. Micrographs of the implanted W specimens revealed the development of three distinct surface morphologies. These morphologies are classified as "blistering", "pitting", and "orientated ridges". Preferential sputtering of the W by the energetic He+ appears to be responsible for pitting and orientated ridges which developed at high fluences (1019 He+/cm2) in the MITE-E. While the orientated ridges were the dominant morphology on the W surface above 700 °C, the pitting was prevalent below 700 °C. The blister morphology was observed at all of the examined temperatures at fluences ≥5x1017 He+/cm2 but disappeared above fluences of 1019 He+/cm 2. The "coral-like" surface morphology on W inherent to He + implantation experiments in HOMER and HELIOS developed from a combination of sources: multiangular ion incidence, ion energy spread (softening), and electron field emission from nano-scale surface features induced by He + implantation. The HOMER and HELIOS devices were found to be better suited for simulation of magnetic fusion environments with off-normal particle incidences, and the MITE-E was found to be more suited for simulating the normal particle incidence of inertial fusion environments.

Quantitative investigation of red blood cell three-dimensional geometric and chemical changes in the storage lesion using digital holographic microscopy.

PubMed

Jaferzadeh, Keyvan; Moon, Inkyu

2015-11-01

Quantitative phase information obtained by digital holographic microscopy (DHM) can provide new insight into the functions and morphology of single red blood cells (RBCs). Since the functionality of a RBC is related to its three-dimensional (3-D) shape, quantitative 3-D geometric changes induced by storage time can help hematologists realize its optimal functionality period. We quantitatively investigate RBC 3-D geometric changes in the storage lesion using DHM. Our experimental results show that the substantial geometric transformation of the biconcave-shaped RBCs to the spherocyte occurs due to RBC storage lesion. This transformation leads to progressive loss of cell surface area, surface-to-volume ratio, and functionality of RBCs. Furthermore, our quantitative analysis shows that there are significant correlations between chemical and morphological properties of RBCs.

Microstructure, Mechanical and Surface Morphological Properties of Al5Ti5Cr Master Alloy as Friction Material Prepared by Stir Die Casting

NASA Astrophysics Data System (ADS)

Ahmed, Syed Faisal; Srivastava, Sanjay; Agarwal, Alka Bani

2018-04-01

Metal matrix composite offers outstanding properties for better performance of disc brakes. In the present study, the composite of AlTiCr master alloy was prepared by stir die casting method. The developed material was reinforced with (0-10 wt%) silicon carbide (SiC) and boron carbide (B4C). The effects of SiC reinforcement from 0 to 10 wt% on mechanical, microstructure and surface morphological properties of Al MMC was investigated and compared with B4C reinforcement. Physical properties like density and micro Vickers hardness number show an increasing trend with an increase in the percentage of SiC and B4C reinforcement. Mechanical properties viz. UTS, yield strength and percentage of elongation are improved with increasing the fraction of reinforcement. The surface morphology and phase were identified from scanning electron microscopy (SEM) and X-ray diffraction analysis and the oxidized product formed during the casting was investigated by Fourier transformation infrared spectroscopy. This confirms the presence of crystallization of corundum (α-Al2O3) in small traces as one of the alumina phases, within casting sample. Micro-structural characterization by SEM depicted that the particles tend to be more agglomerated more and more with the percentage of the reinforcement. The AFM results reveal that the surface roughness value shows a decreasing trend with SiC reinforcement while roughness increases with increase the percentage of B4C.

Morphological Aspects of Oral Denticles in the Sharpnose Shark Rhizoprionodon lalandii (Müller and Henle, 1839) (Elasmobranchii, Carcharhinidae).

PubMed

Ciena, A P; de S Rangel, B; Bruno, C E M; Miglino, M A; de Amorim, A F; Rici, R E G; Watanabe, I

2016-04-01

The oral denticles of some elasmobranchs are found on the surface of the oral cavity and are homologous to those on the body surface, being well developed, independent and non-growing, with varying morphology and distribution depending on the species. The structural and three-dimensional characteristics of oral denticles from the rostro-ventral surface of the sharpnose shark Rhizoprionodon lalandii were described following imaging by both light and scanning electron microscopy. The light microscopy results showed that the triangular shape of the denticles consisted of a base and an apex. Picrosirius staining showed the arrangement of collagen fibres and oral denticles, and a predominance of type-I collagen was found in both structures under polarized light. There was a broad homogeneous distribution of denticles on the ventral surface, forming a leaf-like shape with the cusp facing the caudal region. Interlocking, hexagonal, geometric structures on its rostral side and ridges on the rostral side of the oral denticles were observed under increased magnification. We concluded that the denticle morphology found in R. lalandii differ of others analysed species, and the descriptions of these structures therefore provide important information for the classification of the species. In this species, the main functions can be assigned to help reduce hydrodynamic drag, particularly by this being a species that uses ram ventilation, and to protect the epithelium of the oropharynx of abrasion and parasites. © 2015 Blackwell Verlag GmbH.

Surface morphology of caldera-forming eruption deposits revealed by lidar mapping of Crater Lake National Park, Oregon- Implications for emplacement and surface modification

USGS Publications Warehouse

Robinson, Joel E.; Bacon, Charles R.; Major, Jon J.; Wright, Heather M.; Vallance, James W.

2017-01-01

Large explosive eruptions of silicic magma can produce widespread pumice fall, extensive ignimbrite sheets, and collapse calderas. The surfaces of voluminous ignimbrites are rarely preserved or documented because most terrestrial examples are heavily vegetated, or severely modified by post-depositional processes. Much research addresses the internal sedimentary characteristics, flow processes, and depositional mechanisms of ignimbrites, however, surface features of ignimbrites are less well documented and understood, except for comparatively small-volume deposits of historical eruptions. The ~7,700 calendar year B.P. climactic eruption of Mount Mazama, USA vented ~50 km3 of magma, deposited first as rhyodacite pumice fall and then as a zoned rhyodacite-to-andesite ignimbrite as Crater Lake caldera collapsed. Lidar collected during summer 2010 reveals the remarkably well-preserved surface of the Mazama ignimbrite and related deposits surrounding Crater Lake caldera in unprecedented detail despite forest cover. The ±1 m lateral and ±4 cm vertical resolution lidar allows surface morphologies to be classified. Surface morphologies are created by internal depositional processes and can point to the processes at work when pyroclastic flows come to rest. We describe nine surface features including furrow-ridge sets and wedge-shaped mounds in pumice fall eroded by high-energy pyroclastic surges, flow- parallel ridges that record the passage of multiple pyroclastic flows, perched benches of marginal deposits stranded by more-mobile pyroclastic-flow cores, hummocks of dense clasts interpreted as lag deposit, transverse ridges that mark the compression and imbrication of flows as they came to rest, scarps indicating ignimbrite remobilization, fields of pit craters caused by phreatic explosions, fractures and cracks caused by extensional processes resulting from ignimbrite volume loss, and stream channels eroded in the newly formed surface. The nine morphologies presented here illustrate a dynamic depositional environment that varied spatially and with time during the eruption, and show that multiple processes modified the ignimbrite after deposition, both during and after the eruption.

Surface morphology of caldera-forming eruption deposits revealed by lidar mapping of Crater Lake National Park, Oregon - Implications for deposition and surface modification

NASA Astrophysics Data System (ADS)

Robinson, Joel E.; Bacon, Charles R.; Major, Jon J.; Wright, Heather M.; Vallance, James W.

2017-08-01

Large explosive eruptions of silicic magma can produce widespread pumice fall, extensive ignimbrite sheets, and collapse calderas. The surfaces of voluminous ignimbrites are rarely preserved or documented because most terrestrial examples are heavily vegetated, or severely modified by post-depositional processes. Much research addresses the internal sedimentary characteristics, flow processes, and depositional mechanisms of ignimbrites, however, surface features of ignimbrites are less well documented and understood, except for comparatively small-volume deposits of historical eruptions. The 7700 calendar year B.P. climactic eruption of Mount Manama, USA, vented 50 km3 of magma, deposited first as rhyodacite pumice fall and then as a zoned rhyodacite-to-andesite ignimbrite as Crater Lake caldera collapsed. Lidar collected during summer 2010 reveals the remarkably well-preserved surface of the Manama ignimbrite and related deposits surrounding Crater Lake caldera in unprecedented detail despite forest cover. The ± 1 m lateral and ± 4 cm vertical resolution lidar allows surface morphologies to be classified. Surface morphologies are created by internal depositional processes and can point to the processes at work when pyroclastic flows come to rest. We describe nine surface features including furrow-ridge sets and wedge-shaped mounds in pumice fall eroded by high-energy pyroclastic surges, flow-parallel ridges that record the passage of multiple pyroclastic flows, perched benches of marginal deposits stranded by more-mobile pyroclastic-flow cores, hummocks of dense clasts interpreted as lag deposit, transverse ridges that mark the compression and imbrication of flows as they came to rest, scarps indicating ignimbrite remobilization, fields of closely spaced pits caused by phreatic explosions, fractures and cracks due to extensional processes resulting from ignimbrite volume loss, and stream channels eroded in the newly formed surface. The nine morphologies presented here illustrate a dynamic depositional environment that varied spatially and with time during the eruption, and show that multiple processes modified the ignimbrite after deposition, both during and after the eruption.

Bacterial attachment on titanium surfaces is dependent on topography and chemical changes induced by nonthermal atmospheric pressure plasma.

PubMed

Jeong, Won-Seok; Kwon, Jae-Sung; Lee, Jung-Hwan; Uhm, Soo-Hyuk; Ha Choi, Eun; Kim, Kwang-Mahn

2017-07-26

Here, we investigated the antibacterial effects of chemical changes induced by nonthermal atmospheric pressure plasma (NTAPP) on smooth and rough Ti. The morphologies of smooth and rough surfaces of Ti were examined using scanning electron microscopy (SEM). Both Ti specimens were then treated for 10 min by NTAPP with nitrogen gas. The surface roughness, chemistry, and wettability were examined by optical profilometry, x-ray photoelectron spectroscopy, and water contact angle analysis, respectively. Bacterial attachment was measured by determining the number of colony forming units and by SEM analysis. The rough Ti showed irregular micropits, whereas smooth Ti had a relatively regular pattern on the surface. There were no differences in morphology between samples before and after NTAPP treatment. NTAPP treatment resulted in changes from hydrophobic to hydrophilic properties on rough and smooth Ti; rough Ti showed relatively higher hydrophilicity. Before NTAPP treatment, Streptococcus sanguinis (S. sanguinis) showed greater attachment on rough Ti, and after NTAPP treatment, there was a significant reduction in bacterial attachment. Moreover, the bacterial attachment rate was significantly lower on rough Ti, and the structure of S. sanguinis colonies were significantly changed on NTAPP-treated Ti. NTAPP treatment inhibited bacterial attachment surrounding titanium implants, regardless of surface topography. Therefore, NTAPP treatment on Ti is a next-generation tool for antibacterial applications in the orthopaedic and dental fields.

Distinct differences in striatal dysmorphology between attention deficit hyperactivity disorder boys with and without a comorbid reading disability.

PubMed

Goradia, Dhruman D; Vogel, Sherry; Mohl, Brianne; Khatib, Dalal; Zajac-Benitez, Caroline; Rajan, Usha; Robin, Arthur; Rosenberg, David R; Stanley, Jeffrey A

2016-12-30

There is evidence of greater cognitive deficits in attention deficit hyperactivity disorder with a comorbid reading disability (ADHD/+RD) compared to ADHD alone (ADHD/-RD). Additionally, the striatum has been consistently implicated in ADHD. However, the extent of morphological alterations in the striatum of ADHD/+RD is poorly understood, which is the main purpose of this study. Based on structural MRI images, the surface deformation of the caudate and putamen was assessed in 59 boys matching in age and IQ [19 ADHD/-RD, 15 ADHD/+RD and 25 typically developing controls (TDC)]. A vertex based analysis with multiple comparison correction was conducted to compare ADHD/-RD and ADHD/+RD to TDC. Compared to TDC, ADHD/+RD showed multiple bilateral significant clusters of surface compression. In contrast, ADHD/-RD showed fewer significant clusters of surface compression and restricted to the left side. Regarding the putamen, only ADHD/-RD showed significant clusters of surface compression. Results demonstrate for the first time a greater extent of morphological alterations in the caudate of ADHD/+RD than ADHD/-RD compared to TDC, which may suggest greater implicated cortical areas projecting to the caudate that are associated with the greater neuropsychological impairments observed in ADHD/+RD. Copyright © 2016 Elsevier Ireland Ltd. All rights reserved.

Growth and characterization of epitaxial silver indium diselenide

NASA Astrophysics Data System (ADS)

Pena Martin, Pamela

Photovoltaics (solar cells) are a key player in the renewable energy frontier, and will become increasingly important as their cost per watt continues to drop, especially if fossil fuel costs increase. One particularly promising photovoltaic technology is based on chalcopyrite-structure semiconductors. Within the chalcopyrite compounds the highest efficiency thin film solar cell absorber material to date is Cu(In,Ga)Se2 (CIGS). While current efficiency records are over 21% for single-junction cells, there is still room for improvement. Replacing some of the Cu with Ag has been shown to be beneficial in CIGS devices. However, the Ag- containing chalcopyrites are still relatively unknown in terms of their growth mechanism, energetics, and surface atomic and electronic properties. These are best inferred through study of epitaxial films, yet they have little mention in literature and have not been the subject of a detailed study. This work describes the growth of epitaxial AgInSe2 (AIS) on GaAs substrates, studying the morphology, structure, and surface properties to understand how growth takes place. It also seeks to experimentally determine the surface electronic and atomic structure at the atomic scale to gain insight into the part of the material that forms the heterojunction that collects photon energy in the device. Finally, this work seeks to compare and contrast these findings with what is known about CIGS to determine where similarities and, more importantly, the differences may lie. This study has found that single phase tetragonal AIS can be epitaxially grown on GaAs, as illustrated by x-ray diffraction (XRD), transmission electron microscope (TEM), and surface morphology data. Like CIGS, the close packed polar (112) planes have the lowest energy. The morphology points to a difference in step dynamics, leading to less faceted, straight edged island shapes compared to CIGS. Epitaxial temperature as a function of growth direction shows a different trend in AIS than in CIGS. Interdiffusion of the group III elements across the substrate interface was found to result in an epitaxial intermixed layer between the film and substrate in some cases, which may help mediate the lattice mismatch. At the atomic scale, scanning tunneling microscopy (STM) was used to observe details of the surface morphology, which indicated growth of the (112)A orientation of AIS by a screw dislocation mechanism (other surfaces were not examined by STM but are expected to show similar results). The surface atomic structure was directly imaged for the first time, revealing an arrangement similar to that expected from a bulk terminated surface. The electronic structure shows a gap in surface electronic states with a width comparable to bulk AIS, n-type conduction, and a tail of states near the valence band edge that decay well into the gap. The conduction and valence bands show fluctuations as a function of position on the surface, with greater magnitude in the valence band. The fluctuations in both bands are less than those observed on the surface of CIS by STM. It seems to indicate a reduction in band tails, both in magnitude and spacial extent, in AIS compared to CIS, likely tied to a reduction in point defect concentration at the surface.

Influence of Substrate Bonding and Surface Morphology on Dynamic Organic Layer Growth: Perylenetetracarboxylic Dianhydride on Au(111).

PubMed

Schmidt, Thomas; Marchetto, Helder; Groh, Ullrich; Fink, Rainer H; Freund, Hans-Joachim; Umbach, Eberhard

2018-05-15

We investigated the dynamics of the initial growth of the first epitaxial layers of perylenetetracarboxylic dianhydride (PTCDA) on the Au(111) surface with high lateral resolution using the aberration-corrected spectro-microscope SMART. With this instrument, we could simultaneously study the different adsorption behaviors and layer growth on various surface areas consisting of either a distribution of flat (111) terraces, separated by single atomic steps ("ideal surface"), or on areas with a high density of step bunches and defects ("realistic surface"). The combined use of photoemission electron microscopy, low-energy electron microscopy, and μ-spot X-ray absorption provided a wealth of new information, showing that the growth of the archetype molecule PTCDA not only has similarities but also has significant differences when comparing Au(111) and Ag(111) substrate surfaces. For instance, under otherwise identical preparation conditions, we observed different growth mechanisms on different surface regions, depending on the density of step bunches. In addition, we studied the spatially resolved desorption behavior which also depends on the substrate morphology.

Fabrication of superhydrophobic surface on zinc substrate by 3-trifluoromethylbenzene diazonium tetrafluoroborate salts

NASA Astrophysics Data System (ADS)

Li, Hong; Huang, Chengya; Zhang, Long; Lou, Wanqiu

2014-09-01

In this study we report a new and efficient method of fabricating superhydrophobic surface on zinc plate modified with 3-trifluoromethylbenzene diazonium tetrafluoroborate salts (CF3BD), which shows a water contact angle of 160° for a 4 μl water droplet and a low sliding angle of about 1°. The morphology and chemical composition of as-prepared superhydrophobic zinc surfaces are investigated by means of scanning electron microscopy (SEM), electron probe microanalyzer (EPMA) and FT-IR spectrum. The results show that the organic layers formed on zinc plate surface are provided with the special hierarchical porous microstructure and the low surface energy, which lead to the superhydrophobicity surface on the modified zinc.

Solvothermal synthesis and surface chemistry to control the size and morphology of nanoquartz

DOE PAGES

Sochalski-Kolbus, Lindsay M.; Wang, Hsiu-Wen; Rondinone, Adam Justin; ...

2015-09-29

In this paper, we report a solvothermal synthesis method that allows the crystallization of quartz to occur at a relatively low temperature of 300°C in the form of isolated nanosized euhedral crystals. Transmission electron microscopy (TEM) and small area electron diffraction (SAED) were used to confirm the phases present and their particle sizes, morphologies, and crystallinity of the products. In conclusion, the results show that it is possible to control the size and morphology of the nanoquartz from rough nanospheres to nanorods using fluoride, which templates the nanocrystals and moderates growth.

Characterization and cell behavior of titanium surfaces with PLL/DNA modification via a layer-by-layer technique.

PubMed

Gao, Wenli; Feng, Bo; Lu, Xiong; Wang, Jianxin; Qu, Shuxin; Weng, Jie

2012-08-01

This study describes the fabrication of two types of multilayered films onto titanium by layer-by-layer (LBL) self-assembly, using poly-L-lysine (PLL) as the cationic polyelectrolyte and deoxyribonucleic acid (DNA) as the anionic polyelectrolyte. The assembling process of each component was studied using atomic force microscopy (AFM) and quartz crystal balance (QCM). Zeta potential of the LBL-coated microparticles was measured by dynamic light scattering. Titanium substrates with or without multilayered films were used in osteoblast cell culture experiments to study cell proliferation, viability, differentiation, and morphology. Results of AFM and QCM indicated the progressive build-up of the multilayered coatings. The surface morphology of three types of multilayered films showed elevations in the nanoscale range. The data of zeta potential showed that the surface terminated with PLL displayed positive charge while the surface terminated with DNA displayed negative charge. The proliferation of osteoblasts on modified titanium films was found to be greater than that on control (p < 0.05) after 3 and 7 days culture, respectively. Alamar blue measurement showed that the PLL/DNA-modified films have higher cell viability (p < 0.05) than the control. Still, the alkaline phosphatase activity assay revealed a better differentiated phenotype on three types of multilayered surfaces compared to noncoated controls. Collectively our results suggest that PLL/DNA were successfully used to surface engineer titanium via LBL technique, and enhanced its cell biocompatibility. Copyright © 2012 Wiley Periodicals, Inc.

An Improved Representation of Regional Boundaries on Parcellated Morphological Surfaces

PubMed Central

Hao, Xuejun; Xu, Dongrong; Bansal, Ravi; Liu, Jun; Peterson, Bradley S.

2010-01-01

Establishing the correspondences of brain anatomy with function is important for understanding neuroimaging data. Regional delineations on morphological surfaces define anatomical landmarks and help to visualize and interpret both functional data and morphological measures mapped onto the cortical surface. We present an efficient algorithm that accurately delineates the morphological surface of the cerebral cortex in real time during generation of the surface using information from parcellated 3D data. With this accurate region delineation, we then develop methods for boundary-preserved simplification and smoothing, as well as procedures for the automated correction of small, misclassified regions to improve the quality of the delineated surface. We demonstrate that our delineation algorithm, together with a new method for double-snapshot visualization of cortical regions, can be used to establish a clear correspondence between brain anatomy and mapped quantities, such as morphological measures, across groups of subjects. PMID:21144708

Quantitative Morphologic Analysis of Boulder Shape and Surface Texture to Infer Environmental History: A Case Study of Rock Breakdown at the Ephrata Fan, Channeled Scabland, Washington

NASA Technical Reports Server (NTRS)

Ehlmann, Bethany L.; Viles, Heather A.; Bourke, Mary C.

2008-01-01

Boulder morphology reflects both lithology and climate and is dictated by the combined effects of erosion, transport, and weathering. At present, morphologic information at the boulder scale is underutilized as a recorder of environmental processes, partly because of the lack of a systematic quantitative parameter set for reporting and comparing data sets. We develop such a parameter set, incorporating a range of measures of boulder form and surface texture. We use standard shape metrics measured in the field and fractal and morphometric classification methods borrowed from landscape analysis and applied to laser-scanned molds. The parameter set was pilot tested on three populations of basalt boulders with distinct breakdown histories in the Channeled Scabland, Washington: (1) basalt outcrop talus; (2) flood-transported boulders recently excavated from a quarry; and (3) flood-transported boulders, extensively weathered in situ on the Ephrata Fan surface. Size and shape data were found to distinguish between flood-transported and untransported boulders. Size and edge angles (approximately 120 degrees) of flood-transported boulders suggest removal by preferential fracturing along preexisting columnar joints, and curvature data indicate rounding relative to outcrop boulders. Surface textural data show that boulders which have been exposed at the surface are significantly rougher than those buried by fan sediments. Past signatures diagnostic of flood transport still persist on surface boulders, despite ongoing overprinting by processes in the present breakdown environment through roughening and fracturing in situ. Further use of this quantitative boulder parameter set at other terrestrial and planetary sites will aid in cataloging and understanding morphologic signatures of environmental processes.

Bioinspired, cysteamine-catalyzed co-silicification of (1H, 1H, 2H, 2HPerfluorooctyl) triethoxysilane and tetraethyl orthosilicate: formation of superhydrophobic surfaces.

PubMed

Park, Ji Hun; Kim, Ji Yup; Cho, Woo Kyung; Choi, Insung S

2014-03-01

Bioinspired silicification attracts a great deal of interest because of its physiologically relevant, mild conditions for hydrolysis and condensation of silica precursors, which makes the bioinspired approach superior to the conventional sol–gel process, particularly when dealing with biological entities. However, the morphological control of silica structures with incorporation of functional groups in the bioinspired silicilication has been unexplored. In this work, we co-silicificated (1H, 1H, 2H, 2H-perfluorooctyl)triethoxysilane and tetraethyl orthosilicate to investigate the morphological evolution of fluorinated silica structures in the cetyltrimethylammonium bromide-mediated, cysteamine-catalyzed silicification. The generated micrometer-long wormlike and spherical silica structures display superhydrophobicity after film formation. Interestingly, the measurement of dynamic water contact angles shows that the morphological difference leads to a different wetting state, either the self-cleaning or the pinning state of the superhydrophobic surface.

Normal age-related brain morphometric changes: nonuniformity across cortical thickness, surface area and gray matter volume?

PubMed

Lemaitre, Herve; Goldman, Aaron L; Sambataro, Fabio; Verchinski, Beth A; Meyer-Lindenberg, Andreas; Weinberger, Daniel R; Mattay, Venkata S

2012-03-01

Normal aging is accompanied by global as well as regional structural changes. While these age-related changes in gray matter volume have been extensively studied, less has been done using newer morphological indexes, such as cortical thickness and surface area. To this end, we analyzed structural images of 216 healthy volunteers, ranging from 18 to 87 years of age, using a surface-based automated parcellation approach. Linear regressions of age revealed a concomitant global age-related reduction in cortical thickness, surface area and volume. Cortical thickness and volume collectively confirmed the vulnerability of the prefrontal cortex, whereas in other cortical regions, such as in the parietal cortex, thickness was the only measure sensitive to the pronounced age-related atrophy. No cortical regions showed more surface area reduction than the global average. The distinction between these morphological measures may provide valuable information to dissect age-related structural changes of the brain, with each of these indexes probably reflecting specific histological changes occurring during aging. Published by Elsevier Inc.

Phytoremediation in the tropics--influence of heavy crude oil on root morphological characteristics of graminoids.

PubMed

Merkl, Nicole; Schultze-Kraft, Rainer; Infante, Carmen

2005-11-01

When studying species for phytoremediation of petroleum-contaminated soils, one of the main traits is the root zone where enhanced petroleum degradation takes place. Root morphological characteristics of three tropical graminoids were studied. Specific root length (SRL), surface area, volume and average root diameter (ARD) of plants grown in crude oil-contaminated and uncontaminated soil were compared. Brachiaria brizantha and Cyperus aggregatus showed coarser roots in polluted soil compared to the control as expressed in an increased ARD. B. brizantha had a significantly larger specific root surface area in contaminated soil. Additionally, a shift of SRL and surface area per diameter class towards higher diameters was found. Oil contamination also caused a significantly smaller SRL and surface area in the finest diameter class of C. aggregatus. The root structure of Eleusine indica was not significantly affected by crude oil. Higher specific root surface area was related to higher degradation of petroleum hydrocarbons found in previous studies.

Critical Role of Surface Energy in Guiding Crystallization of Solution-Coated Conjugated Polymer Thin Films

DOE PAGES

Zhang, Fengjiao; Mohammadi, Erfan; Luo, Xuyi; ...

2017-10-02

It is well-known that substrate surface properties have a profound impact on morphology of thin films solution coated atop and the resulting solid-state properties. However, design rules for guiding the substrate selection have not yet been established. Such design rules are particularly important for solution coated semiconducting polymers, as the substratedirected thin film morphology can impact charge transport properties by orders of magnitude. We hypothesize that substrate surface energies dictate the thin film morphology by modulating the free energy barrier to heterogeneous nucleation. To test this hypothesis, we systematically vary the substrate surface energy via surface functionalization techniques. We performmore » in-depth morphology and device characterizations to establish the relationship between substrate surface energy, thin film morphology and charge transport properties, employing a donor-accepter (D-A) conjugated polymer. Here, we find that decreasing the substrate surface energy progressively increases thin film crystallinity, degree of molecular ordering and extent of domain alignment. Notably, the enhanced morphology on the lowest surface energy substrate lead to a 10-fold increase in the charge carrier mobility. We further develop a free energy model relating the substrate surface energy to the penalty of heterogeneous nucleation from solution in the thin film geometry. The model correctly predicts the experimental trend, thereby validating our hypothesis. This work is a significant step towards establishing design rules and understanding the critical role of substrates in determining morphology of solution coated thin films.« less

Critical Role of Surface Energy in Guiding Crystallization of Solution-Coated Conjugated Polymer Thin Films

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

Zhang, Fengjiao; Mohammadi, Erfan; Luo, Xuyi

It is well-known that substrate surface properties have a profound impact on morphology of thin films solution coated atop and the resulting solid-state properties. However, design rules for guiding the substrate selection have not yet been established. Such design rules are particularly important for solution coated semiconducting polymers, as the substratedirected thin film morphology can impact charge transport properties by orders of magnitude. We hypothesize that substrate surface energies dictate the thin film morphology by modulating the free energy barrier to heterogeneous nucleation. To test this hypothesis, we systematically vary the substrate surface energy via surface functionalization techniques. We performmore » in-depth morphology and device characterizations to establish the relationship between substrate surface energy, thin film morphology and charge transport properties, employing a donor-accepter (D-A) conjugated polymer. Here, we find that decreasing the substrate surface energy progressively increases thin film crystallinity, degree of molecular ordering and extent of domain alignment. Notably, the enhanced morphology on the lowest surface energy substrate lead to a 10-fold increase in the charge carrier mobility. We further develop a free energy model relating the substrate surface energy to the penalty of heterogeneous nucleation from solution in the thin film geometry. The model correctly predicts the experimental trend, thereby validating our hypothesis. This work is a significant step towards establishing design rules and understanding the critical role of substrates in determining morphology of solution coated thin films.« less

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

PubMed

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

2017-10-01

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

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

Wang, Hongfen, E-mail: wanghongfen11@163.com; Wang, Zhiqi; Chen, Shougang

Molybdenum carbides with surfactants as carbon sources were prepared using the carbothermal reduction of the appropriate precursors (molybdenum oxides deposited on surfactant micelles) at 1023 K under hydrogen gas. The carburized products were characterized using scanning electron microscopy (SEM), X-ray diffraction and BET surface area measurements. From the SEM images, hollow microspherical and rod-like molybdenum carbides were observed. X-ray diffraction patterns showed that the annealing time of carburization had a large effect on the conversion of molybdenum oxides to molybdenum carbides. And BET surface area measurements indicated that the difference of carbon sources brought a big difference in specific surfacemore » areas of molybdenum carbides. - Graphical abstract: Molybdenum carbides having hollow microspherical and hollow rod-like morphologies that are different from the conventional monodipersed platelet-like morphologies. Highlights: Black-Right-Pointing-Pointer Molybdenum carbides were prepared using surfactants as carbon sources. Black-Right-Pointing-Pointer The kinds of surfactants affected the morphologies of molybdenum carbides. Black-Right-Pointing-Pointer The time of heat preservation at 1023 K affected the carburization process. Black-Right-Pointing-Pointer Molybdenum carbides with hollow structures had larger specific surface areas.« less

Separating Bulk and Surface Contributions to Electronic Excited-State Processes in Hybrid Mixed Perovskite Thin Films via Multimodal All-Optical Imaging

DOE PAGES

Simpson, Mary Jane; Doughty, Benjamin; Das, Sanjib; ...

2017-07-04

A comprehensive understanding of electronic excited-state phenomena underlying the impressive performance of solution-processed hybrid halide perovskite solar cells requires access to both spatially resolved electronic processes and corresponding sample morphological characteristics. In this paper, we demonstrate an all-optical multimodal imaging approach that enables us to obtain both electronic excited-state and morphological information on a single optical microscope platform with simultaneous high temporal and spatial resolution. Specifically, images were acquired for the same region of interest in thin films of chloride containing mixed lead halide perovskites (CH 3NH 3PbI 3–xCl x) using femtosecond transient absorption, time-integrated photoluminescence, confocal reflectance, and transmissionmore » microscopies. Comprehensive image analysis revealed the presence of surface- and bulk-dominated contributions to the various images, which describe either spatially dependent electronic excited-state properties or morphological variations across the probed region of the thin films. Finally, these results show that PL probes effectively the species near or at the film surface.« less

Morphology of size-selected Ptn clusters on CeO2(111)

NASA Astrophysics Data System (ADS)

Shahed, Syed Mohammad Fakruddin; Beniya, Atsushi; Hirata, Hirohito; Watanabe, Yoshihide

2018-03-01

Supported Pt catalysts and ceria are well known for their application in automotive exhaust catalysts. Size-selected Pt clusters supported on a CeO2(111) surface exhibit distinct physical and chemical properties. We investigated the morphology of the size-selected Ptn (n = 5-13) clusters on a CeO2(111) surface using scanning tunneling microscopy at room temperature. Ptn clusters prefer a two-dimensional morphology for n = 5 and a three-dimensional (3D) morphology for n ≥ 6. We further observed the preference for a 3D tri-layer structure when n ≥ 10. For each cluster size, we quantitatively estimated the relative fraction of the clusters for each type of morphology. Size-dependent morphology of the Ptn clusters on the CeO2(111) surface was attributed to the Pt-Pt interaction in the cluster and the Pt-O interaction between the cluster and CeO2(111) surface. The results obtained herein provide a clear understanding of the size-dependent morphology of the Ptn clusters on a CeO2(111) surface.

Morphology of size-selected Ptn clusters on CeO2(111).

PubMed

Shahed, Syed Mohammad Fakruddin; Beniya, Atsushi; Hirata, Hirohito; Watanabe, Yoshihide

2018-03-21

Supported Pt catalysts and ceria are well known for their application in automotive exhaust catalysts. Size-selected Pt clusters supported on a CeO 2 (111) surface exhibit distinct physical and chemical properties. We investigated the morphology of the size-selected Pt n (n = 5-13) clusters on a CeO 2 (111) surface using scanning tunneling microscopy at room temperature. Pt n clusters prefer a two-dimensional morphology for n = 5 and a three-dimensional (3D) morphology for n ≥ 6. We further observed the preference for a 3D tri-layer structure when n ≥ 10. For each cluster size, we quantitatively estimated the relative fraction of the clusters for each type of morphology. Size-dependent morphology of the Pt n clusters on the CeO 2 (111) surface was attributed to the Pt-Pt interaction in the cluster and the Pt-O interaction between the cluster and CeO 2 (111) surface. The results obtained herein provide a clear understanding of the size-dependent morphology of the Pt n clusters on a CeO 2 (111) surface.

Influence of mechanical and chemical surface treatments on the formation of bone-like structure in cpTi for endosseous dental implants

NASA Astrophysics Data System (ADS)

Parsikia, Farhang; Amini, Pupak; Asgari, Sirous

2012-10-01

Commercially pure titanium samples were exposed to grit blasting and acid-alkali treatments to obtain a variety of surface compositions and morphologies. Contact roughness test and microstructural studies were employed to study the surface topography of the samples. The nature and chemical composition of surface phases were evaluated using X-ray diffraction and microanalysis techniques. Selected samples first exposed to in vitro environment were then tested to determine the surface morphology and surface microstructure. Based on the data presented in this work, it is suggested that grit blasting process utilized prior to chemical treatment stage, yields a high quality surface morphology. Such a surface morphology is expected to have superior tribological characteristics after osseointegration. Also, it appeared that the reverse sequence of processing resulted in a better biocompatibility of the product manifested by negligible amount of residual alumina on the sample surface.

Effect of laser activated bleaching on the chemical stability and morphology of intracoronal dentin.

PubMed

Lopes, Fabiane Carneiro; Roperto, Renato; Akkus, Anna; Akkus, Ozan; Palma-Dibb, Regina Guenka; de Sousa-Neto, Manoel Damião

2018-02-01

To evaluate the effect of the bleaching with 35% hydrogen peroxide either activated or not by a 970nm diode laser on the chemical stability and dentin surface morphology of intracoronary dentin. Twenty-seven slabs of intracoronary dentin specimens (3×3mm) were distributed into three groups (n=9), according to surface treatment: HP - 35% hydrogen peroxide (1×4'), DL - 970nm diode laser (1×30"/0,8W/10Hz), HP+DL - 35% HP activated with 970nm diode laser (1×30"/0,8W/10Hz leaving the gel in contact to the surface for 4' after activation). Three Raman spectra from each fragment were obtained to calculate the mean intensity of peaks of inorganic component (a.u.), organic collagen content (a.u.), and the ratio of inorganic/organic content, before and after treatment. Analyses of the samples by confocal laser microscopy were performed to evaluate the surface roughness, percentage of tubules, perimeter and area percentage of tubules, before and after treatment. Data were analyzed by Kruskal-Wallis, Dunn's, and Wilcoxon test (P<0.05). Data analysis showed that HP+DL did not change the inorganic content peaks 8.31 [29.78] or the inorganic/organic ratio 3.37 [14.67] (P>0.05). Similarly, DL did not affect the chemical stability of the dentin surface (P>0.05). However, HP significantly increased inorganic content peaks 10.87 [22.62], as well as the inorganic/organic ratio 6.25 [27.78] (P<0.05). Regarding the morphological alterations, all surface treatments increase tubules exposure; HP treatment significantly increases perimeter and area percentage; and HP+DL increases surface roughness. Bleaching HP combined with DL offers an improvement in terms of intracoronal dentin surface protection, yielding better maintenance of dentin chemical stability and morphology. Copyright © 2017 Elsevier Ltd. All rights reserved.

Electron mobility enhancement in metalorganic-vapor-phase-epitaxy-grown InAlN high-electron-mobility transistors by control of surface morphology of spacer layer

NASA Astrophysics Data System (ADS)

Yamada, Atsushi; Ishiguro, Tetsuro; Kotani, Junji; Nakamura, Norikazu

2018-01-01

We demonstrated low-sheet-resistance metalorganic-vapor-phase-epitaxy-grown InAlN high-electron-mobility transistors using AlGaN spacers with excellent surface morphology. We systematically investigated the effects of AlGaN spacer growth conditions on surface morphology and electron mobility. We found that the surface morphology of InAlN barriers depends on that of AlGaN spacers. Ga desorption from AlGaN spacers was suppressed by increasing the trimethylaluminum (TMA) supply rate, resulting in the small surface roughnesses of InAlN barriers and AlGaN spacers. Moreover, we found that an increase in the NH3 supply rate also improved the surface morphologies of InAlN barriers and AlGaN spacers as long as the TMA supply rate was high enough to suppress the degradation of GaN channels. Finally, we realized a low sheet resistance of 185.5 Ω/sq with a high electron mobility of 1210 cm2 V-1 s-1 by improving the surface morphologies of AlGaN spacers and InAlN barriers.

Assembling strategy to synthesize palladium modified kaolin nanocomposites with different morphologies

PubMed Central

Li, Xiaoyu; Ouyang, Jing; Zhou, Yonghua; Yang, Huaming

2015-01-01

Nanocomposites of aluminosilicate minerals, kaolins (kaolinite and halloysite) with natural different morphologies assembling with palladium (Pd) nanoparticles have been successfully synthesized through strong electrostatic adsorption and chemical bonding after surface modification with 3-aminopropyl triethoxysilane (APTES). Meanwhile, the influence of different morphologies supports on catalytic hydrogenation properties was explored. The surface concentration of amino groups on the kaolins was related to the morphology and surface nature. Electronmicroscopy revealed that the monodisperse Pd nanoparticles were uniformly deposited onto the surface of kaolins, ranging in diameter from 0.5 nm to 5.5 nm. The functional groups could not only improve the dispersion of kaolins with different morphologies in solution, but also enhance the interaction between Pd precursors and kaolins, thus preventing small Pd nanoparticles from agglomerating and leading to high activity for the catalytic hydrogenation of styrene. Pd-FK@APTES was more active compared to other samples. Selecting the kaolin morphology with a different surface nature allows the selective surface modification of a larger fraction of the reactive facets on which the active sites can be enriched and tuned. This desirable surface coordination of catalytically active atoms could substantially improve catalytic activity. PMID:26333629

Assembling strategy to synthesize palladium modified kaolin nanocomposites with different morphologies

NASA Astrophysics Data System (ADS)

Li, Xiaoyu; Ouyang, Jing; Zhou, Yonghua; Yang, Huaming

2015-09-01

Nanocomposites of aluminosilicate minerals, kaolins (kaolinite and halloysite) with natural different morphologies assembling with palladium (Pd) nanoparticles have been successfully synthesized through strong electrostatic adsorption and chemical bonding after surface modification with 3-aminopropyl triethoxysilane (APTES). Meanwhile, the influence of different morphologies supports on catalytic hydrogenation properties was explored. The surface concentration of amino groups on the kaolins was related to the morphology and surface nature. Electronmicroscopy revealed that the monodisperse Pd nanoparticles were uniformly deposited onto the surface of kaolins, ranging in diameter from 0.5 nm to 5.5 nm. The functional groups could not only improve the dispersion of kaolins with different morphologies in solution, but also enhance the interaction between Pd precursors and kaolins, thus preventing small Pd nanoparticles from agglomerating and leading to high activity for the catalytic hydrogenation of styrene. Pd-FK@APTES was more active compared to other samples. Selecting the kaolin morphology with a different surface nature allows the selective surface modification of a larger fraction of the reactive facets on which the active sites can be enriched and tuned. This desirable surface coordination of catalytically active atoms could substantially improve catalytic activity.

Assembling strategy to synthesize palladium modified kaolin nanocomposites with different morphologies.

PubMed

Li, Xiaoyu; Ouyang, Jing; Zhou, Yonghua; Yang, Huaming

2015-09-03

Nanocomposites of aluminosilicate minerals, kaolins (kaolinite and halloysite) with natural different morphologies assembling with palladium (Pd) nanoparticles have been successfully synthesized through strong electrostatic adsorption and chemical bonding after surface modification with 3-aminopropyl triethoxysilane (APTES). Meanwhile, the influence of different morphologies supports on catalytic hydrogenation properties was explored. The surface concentration of amino groups on the kaolins was related to the morphology and surface nature. Electronmicroscopy revealed that the monodisperse Pd nanoparticles were uniformly deposited onto the surface of kaolins, ranging in diameter from 0.5 nm to 5.5 nm. The functional groups could not only improve the dispersion of kaolins with different morphologies in solution, but also enhance the interaction between Pd precursors and kaolins, thus preventing small Pd nanoparticles from agglomerating and leading to high activity for the catalytic hydrogenation of styrene. Pd-FK@APTES was more active compared to other samples. Selecting the kaolin morphology with a different surface nature allows the selective surface modification of a larger fraction of the reactive facets on which the active sites can be enriched and tuned. This desirable surface coordination of catalytically active atoms could substantially improve catalytic activity.

Processing and Characterization of Graphene/Polyimide-Nickel Oxide Hybrid Nanocomposites for Advanced Energy Storage in Supercapacitor Applications

NASA Astrophysics Data System (ADS)

Okafor, Patricia A.

This research is focused on enhancing electrochemical properties/energy storage capabilities of graphene-polyimide composites. The composite's dense morphology/structure limits ionic penetration owing to high bulk resistances resulting in poor electrochemical performance. Modification of the composite's morphology by incorporation of facile pores during curing increases total available surface area to electrolyte species. Presence of pores increases adsorption sites for double layer formation and increases overall capacitance. In this work, aromatic polyimide precursors were reacted in the presence of nano-graphene fillers to synthesize graphene-polyimide composite films. The resulting composite was very stiff and dense with a high glass transition temperature (Tg) of 400 °C and storage modulus of 7.20 GPa. Selective decomposition of a thermally labile poly(acrylic ester) resin introduced into the composite during synthesis creates pores of varying size and shapes which increases available surface area of embedded stacked graphene sheets available for ion adsorption and double layer formation. Proper control over pore size and specific surface area of pores was required to ensure good performance in terms of both power delivery rate and energy storage capacity. Dynamic mechanical studies on modified composite showed very good mechanical property while shifts in imide peaks to lower wave numbers in Raman and Fourier transform spectroscopy (FTIR) confirms presence of chemical interaction between graphene filler and polymer matrix confirming uniform dispersion of fillers in the material. Thermogravimetric analysis (TGA) shows thermal stability for the composite systems at temperatures above 700°C. To further optimize material's energy storage capabilities, a hybrid composite was formed by depositing relatively cheap nickel oxide onto the modified porous composite system by a two-step process. A remarkable improvement in electrochemical properties up to an order of magnitude was observed. Electrochemical performance of the hybrid system showed strong dependence on deposition current density, deposition time and substrate pore morphology. Increased NiO particle size (aggregates) was observed with increased deposition time and current density which had a significant impact on charge transfer resistance and specific capacitance. Several correlations were made between composite's morphology and obtained properties. The material's morphology showed direct correlation with double layer capacitance, charge capacity, bulk resistance and sheet conductivity measured using cyclic voltammetry (CV), cyclic charge discharge (CCD), electrochemical impedance spectroscopy (EIS) and four probe measurements respectively. It was observed that smaller well distributed pores showed enhanced properties compared to larger pores. Material's overall performance shows a linear dependence on porosity. The overall electrochemical and electrical behavior of the system is directly linked to the composite's morphology and structure as will be demonstrated in this thesis work.

Mechanism for atmosphere dependence of laser damage morphology in HfO2/SiO2 high reflective films

NASA Astrophysics Data System (ADS)

Pu, Yunti; Ma, Ping; Chen, Songlin; Zhu, Jiliang; Wang, Gang; Pan, Feng; Sun, Ping; Zhu, Xiaohong; Zhu, Jianguo; Xiao, Dingquan

2012-07-01

We show in this paper single-shot and multi-shot laser-induced damage thresholds (LIDTs) of HfO2/SiO2 high reflective films (the reflectance = 99.9%) are affected by the presence of a water layer absorbed on the surface of the porous films. When the water layer was removed with the process of pumping, the single-shot LIDT measured in vacuum dropped to ˜48% of that measured in air, while the multi-shot LIDT in vacuum dropped to ˜47% of its atmospheric value for the high reflective films. Typical damage micrographs of the films in air and in vacuum were obtained, showing distinct damage morphologies. Such atmosphere dependence of the laser damage morphology was found to originate from that formation of a water layer on the surface of porous films could cause an increase of horizontal thermal conductivity and a reduction of vertical thermal conductivity. Moreover, laser-induced periodic ripple damages in air were found in the SiO2 layer from the micrographs. A model of deformation kinematics was used to illustrate the occurrence of the periodic ripple damage, showing that it could be attributed to a contraction of the HfO2 layer under irradiation by the 5-ns laser pulses in air.

The role of surface implant treatments on the biological behavior of SaOS-2 osteoblast-like cells. An in vitro comparative study.

PubMed

Conserva, Enrico; Menini, Maria; Ravera, Giambattista; Pera, Paolo

2013-08-01

The aim of this study was an in vitro comparison of osteoblast adhesion, proliferation and differentiation related to six dental implants with different surface characteristics, and to determine if the interaction between cells and implant is influenced by surface structure and chemical composition. Six types of implants were tested, presenting four different surface treatments: turned, sandblasted, acid-etched, anodized. The implant macro- and microstructure were analyzed using SEM, and the surface chemical composition was investigated using energy-dispersive X-ray analysis. SaOS-2 osteoblasts were used for the evaluation of cell adhesion and proliferation by SEM, and cell viability in contact with the various surfaces was determined using cytotoxicity MTT assays. Alkaline phosphatase (ALP) enzymatic activity in contact with the six surfaces was evaluated. Data relative to MTT assay and ALP activity were statistically analyzed using Kruskal-Wallis not parametric test and Nemenyi-Damico-Wolfe-Dunn post hoc test. All the implants tested supported cell adhesion, proliferation and differentiation, revealing neither organic contaminants nor cytotoxicity effects. The industrial treatments investigated changed the implant surface microscopic aspect and SaOS-2 cell morphology appeared to be influenced by the type of surface treatment at 6, 24, and 72 h of growth. SaOS-2 cells spread more rapidly on sandblasted surfaces. Turned surfaces showed the lowest cell proliferation at SEM observation. Sandblasted surfaces showed the greatest ALP activity values per cell, followed by turned surfaces (P < 0.05). On the base of this in vitro investigation, differently surfaced implants affected osteoblast morphology, adhesion, proliferation, and differentiation. Sandblasted surfaces promoted the most suitable osteoblast behavior. © 2012 John Wiley & Sons A/S.

Correlation and sex differences between ankle and knee cartilage morphology determined by quantitative magnetic resonance imaging

PubMed Central

Eckstein, F; Siedek, V; Glaser, C; Al-Ali, D; Englmeier, K; Reiser, M; Graichen, H

2004-01-01

Objective: To study the correlation between ankle and knee cartilage morphology to test the hypothesis that knee joint cartilage loss in gonarthritis can be estimated retrospectively using quantitative MRI analysis of the knee and ankle and established regression equations; and to test the hypothesis that sex differences in joint surface area are larger in the knee than the ankle, which may explain the greater incidence of knee osteoarthritis in elderly women than in elderly men. Methods: Sagittal MR images (3D FLASH WE) of the knee and hind foot were acquired in 29 healthy subjects (14 women, 15 men; mean (SD) age, 25 (3) years), with no signs joint disease. Cartilage volume, thickness, and joint surface area were determined in the knee, ankle, and subtalar joint. Results: Knee cartilage volumes and joint surface areas showed only moderate correlations with those of the ankle and subtalar joint (r = 0.33 to 0.81). The correlations of cartilage thickness between the two joints were weaker still (r = –0.05 to 0.53). Sex differences in cartilage morphology at the knee and the ankle were similar, with surface areas being –17.5% to –23.5% lower in women than in men. Conclusions: Only moderate correlations in cartilage morphology of healthy subjects were found between knee and ankle. It is therefore impractical to estimate knee joint cartilage loss a posteriori in cross sectional studies by measuring the hind foot and then applying a scaling factor. Sex differences in cartilage morphology do not explain differences in osteoarthritis incidence between men and women in the knee and ankle. PMID:15479900

Effect of thermal treatment on Zn nanodisks

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

Acuña-Avila, Pedro E., E-mail: pacunaa004@alumno.uaemex.mx; López, Roberto; Vigueras-Santiago, Enrique

2015-06-15

Metallic Zn nanodisks with hexagonal morphology were obtained onto glass substrate under vacuum thermal evaporation. A thermal characterization of Zn nanodiks showed a lower oxidation temperature than source powder Zn. Different thermal treatment on Zn nanodisks played an important role on the morphology, crystal size and surface vibrational modes of ZnO. The growth of ZnO nanoneedles started at the edge of metallic zinc hexagonal structures according with SEM images, the higher temperature the longer needles were grown. XRD diffractogram confirmed the wurtzite structure of ZnO with metallic nuclei. A wide band between 530 and 580 cm{sup −1} of Raman scatteringmore » corresponded at surface vibrational modes not observed at higher temperature.« less

Synthesis of Bi0.9Nd0.1FeO3 multiferroic nanoceramic by sol-gel method and its structural, surface morphology and dielectric analysis

NASA Astrophysics Data System (ADS)

Das, S.; Bera, K. P.; Nath, T. K.

2017-05-01

Synthesis of Nd-doped BFO multiferroic nanoceramic by the conventional sol-gel method has been carried out. HRXRD and FESEM have been used for the structural analysis to confirm the triclinic structure and to obtain the surface morphology showing agglomeration and to find out the size of the nanoparticles. A high precision LCR meter has been used to record the dielectric constants at various temperatures. Several anomalies are observed whose physical explanations have been given. Space charge polarization effect and magnetoelectric coupling have been confirmed in the synthesized Bi0.9Nd0.1FeO3 nanoceramic sample.

Novel insights into pericarp, protein body globoids of aleurone layer, starchy granules of three cereals gained using atomic force microscopy and environmental scanning electronic microscopy

PubMed Central

Antonini, Elena; Zara, Carolina; Valentini, Laura; Gobbi, Pietro; Menotta, Michele

2018-01-01

In this study, we applied Environmental Scanning Electron Microscopy-Energy Dispersive Spectroscopy (ESEM-EDS) and Atomic Force Microscopy (AFM) analysis to three different cereal caryopses: barley, oat and einkorn wheat. The morphological structures, chemical elemental composition and surface characteristics of the three cereals were described. Regarding the morphology, barley showed the thickest pericarp, providing a strong barrier to digestion and absorption of nutrients. The aleurone layer of each cereal type contained protein body globoids within its cells. Large type-A and small type-B starchy granules were revealed in the endosperm of barley and einkorn wheat, whereas irregular starchy granules were found in oats. The starchy granule elemental composition, detected by ESEM-EDS, was rather homogenous in the three cereals, whereas the pericarp and protein body globoids showed heterogeneity. In the protein body globoids, oats showed higher P and K concentrations than barley and einkorn wheat. Regarding the topographic profiles, detected by AFM, einkorn wheat starchy granules showed a surface profile that differed significantly from that of oats and barley, which were quite similar to one another. The present work provides insights into the morphological and chemical makeup of the three grains shedding light on the higher bio-accessibility of einkorn wheat nutrients compared to barley and oats, providing important suggestions for human nutrition and technological standpoints. PMID:29569870

Novel insights into pericarp, protein body globoids of aleurone layer, starchy granules of three cereals gained using atomic force microscopy and environmental scanning electronic microscopy.

PubMed

Antonini, Elena; Zara, Carolina; Valentini, Laura; Gobbi, Pietro; Ninfali, Paolino; Menotta, Michele

2018-02-05

In this study, we applied Environmental Scanning Electron Microscopy-Energy Dispersive Spectroscopy (ESEM-EDS) and Atomic Force Microscopy (AFM) analysis to three different cereal caryopses: barley, oat and einkorn wheat. The morphological structures, chemical elemental composition and surface characteristics of the three cereals were described. Regarding the morphology, barley showed the thickest pericarp, providing a strong barrier digestion and absorption of nutrients. The aleurone layer of each cereal type contained protein body globoids within its cells. Large type-A and small type-B starchy granules were revealed in the endosperm of barley and einkorn wheat, whereas irregular starchy granules were found in oats. The starchy granule elemental composition, detected by ESEM-EDS, was rather homogenous in the three cereals, whereas the pericarp and protein body globoids showed heterogeneity. In the protein body globoids, oats showed higher P and K concentrations than barley and einkorn wheat. Regarding the topographic profiles, detected by AFM, einkorn wheat starchy granules showed a surface profile that differed significantly from that of oats and barley, which were quite similar to one another. The present work provides insights into the morphological and chemical makeup of the three grains shedding light on the higher bio-accessibility of einkorn wheat nutrients compared to barley and oats, providing important suggestions for human nutrition and technological standpoints.

Membrane translocation of t-SNARE protein syntaxin-4 abrogates ground-state pluripotency in mouse embryonic stem cells

PubMed Central

Hagiwara-Chatani, Natsumi; Shirai, Kota; Kido, Takumi; Horigome, Tomoatsu; Yasue, Akihiro; Adachi, Naoki; Hirai, Yohei

2017-01-01

Embryonic stem (ES) and induced pluripotent stem (iPS) cells are attractive tools for regenerative medicine therapies. However, aberrant cell populations that display flattened morphology and lose ground-state pluripotency often appear spontaneously, unless glycogen synthase kinase 3β (GSK3β) and mitogen-activated protein kinase kinase (MEK1/2) are inactivated. Here, we show that membrane translocation of the t-SNARE protein syntaxin-4 possibly is involved in this phenomenon. We found that mouse ES cells cultured without GSK3β/MEK1/2 inhibitors (2i) spontaneously extrude syntaxin-4 at the cell surface and that artificial expression of cell surface syntaxin-4 induces appreciable morphological changes and mesodermal differentiation through dephosphorylation of Akt. Transcriptome analyses revealed several candidate elements responsible for this, specifically, an E-to P-cadherin switch and a marked downregulation of Zscan4 proteins, which are DNA-binding proteins essential for ES cell pluripotency. Embryonic carcinoma cell lines F9 and P19CL6, which maintain undifferentiated states independently of Zscan4 proteins, exhibited similar cellular behaviors upon stimulation with cell surface syntaxin-4. The functional ablation of E-cadherin and overexpression of P-cadherin reproduced syntaxin-4-induced cell morphology, demonstrating that the E- to P-cadherin switch executes morphological signals from cell surface syntaxin-4. Thus, spontaneous membrane translocation of syntaxin-4 emerged as a critical element for maintenance of the stem-cell niche. PMID:28057922

Effect of TiO2 nanoparticles doping on structural and electrical properties of PVA: NaBr polymer electrolyte

NASA Astrophysics Data System (ADS)

Sagar, Rohan N.; Ravindrachary, V.; Guruswamy, B.; Hegde, Shreedatta; Mahanthesh, B. K.; Kumari, R. Padma

2018-05-01

The effect of TiO2 nanoparticles on morphology and electrical properties of PVA: NaBr composite films were carried out using various techniques. The pure and TiO2 nanoparticle doped PVA: NaBr composite films were prepared using solvent casting method. The FTIR spectral studies shows that the Ti+ ions of TiO2 interacts with hydroxyl group (OH) of PVA via hydrogen bonding and forms the charge transfer complexes (CTC). These interactions are of inter/intra molecular type and affects the surface morphology as well as the electrical properties of composite films. XRD study shows that the crystallinity of the composite increases with doping level. SEM studies shows that the increase in roughness of the surface of the composite films and uniform dispersion of nanofillers in polymer matrix. Electrical properties are analyzed using impedance analyzer and higher conductivity (10-4Scm-1) is achieved for 5 wt % TiO2 doping concentration.

In-situ Polymerization of Polyaniline/Polypyrrole Copolymer using Different Techniques

NASA Astrophysics Data System (ADS)

Hammad, A. S.; Noby, H.; Elkady, M. F.; El-Shazly, A. H.

2018-01-01

The morphology and surface area of the poly(aniline-co-pyrrole) copolymer (PANPY) are important properties which improve the efficiency of the copolymer in various applications. In this investigation, different techniques were employed to produce PANPY in different morphologies. Aniline and pyrrole were used as monomers, and ammonium peroxydisulfate (APS) was used as an oxidizer with uniform molar ratio. Rapid mixing, drop-wise mixing, and supercritical carbon dioxide (ScCO2) polymerization techniques were appointed. The chemical structure, crystallinity, porosity, and morphology of the composite were distinguished by Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD), Brunauer, Emmett and Teller (BET) analysis, and transmission electron microscopy (TEM) respectively. The characterization tests indicated that the polyaniline/polypyrrole copolymer was successfully prepared with different morphologies. Based on the obtained TEM, hollow nanospheres were formed using rapid mixing technique with acetic acid that have a diameter of 75 nm and thickness 26 nm approximately. Also, according to the XRD, the produced structures have a semi- crystalline structure. The synthesized copolymer with ScCO2-assisted polymerization technique showed improved surface area (38.1 m2/g) with HCl as dopant.

Synthesis and Characterization of TiO2/SiO2 Thin Film via Sol-Gel Method

NASA Astrophysics Data System (ADS)

Halin, D. S. C.; Abdullah, M. M. A. B.; Mahmed, N.; Malek, S. N. A. Abdul; Vizureanu, P.; Azhari, A. W.

2017-06-01

TiO2/SiO2 thin films were prepared by sol-gel spin coating method. Structural, surface morphology and optical properties were investigated for different annealing temperatures at 300°C, 400°C and 500°C. X-ray diffraction pattern show that brookite TiO2 crystalline phase with SiO2 phase presence at 300°C. At higher temperatures of 400-500°C, the only phase presence was brookite. The surface morphology of film was characterized by scanning electron microscopy (SEM). The films annealed at 300°C shows an agglomeration of small flaky with crack free. When the temperature of annealing increase to 400-500°C, the films with large flaky and large cracks film were formed which was due to surface tension between the film and the air during the drying process. The UV-Vis spectroscopy shows that the film exhibits a low transmittance around 30% which was due to the substrate is inhomogeneously covered by the films. In order to improve the coverage of the film on the substrate, it has to repeatable the spin coating to ensure the substrate is fully covered by the films.

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

Atanasov, Petar A., E-mail: paatanas@ie.bas.bg; Nedyalkov, Nikolay N.; Valova, Eugenia I.

We present an experimental analysis on surface structuring of polydimethylsiloxane films with UV (263 nm) femtosecond laser pulses, in air. Laser processed areas are analyzed by optical microscopy, SEM, and μ-Raman spectroscopy. The laser-treated sample shows the formation of a randomly nanostructured surface morphology. μ-Raman spectra, carried out at both 514 and 785 nm excitation wavelengths, prior and after laser treatment allow evidencing the changes in the sample structure. The influence of the laser fluence on the surface morphology is studied. Finally, successful electro-less metallization of the laser-processed sample is achieved, even after several months from the laser-treatment contrary to previous observationmore » with nanosecond pulses. Our findings address the effectiveness of fs-laser treatment and chemical metallization of polydimethylsiloxane films with perspective technological interest in micro-fabrication devices for MEMS and nano-electromechanical systems.« less

Structure, composition and morphology of bioactive titanate layer on porous titanium surfaces

NASA Astrophysics Data System (ADS)

Li, Jinshan; Wang, Xiaohua; Hu, Rui; Kou, Hongchao

2014-07-01

A bioactive coating was produced on pore surfaces of porous titanium samples by an amendatory alkali-heat treatment method. Porous titanium was prepared by powder metallurgy and its porosity and average size were 45% and 135 μm, respectively. Coating morphology, coating structure and phase constituents were examined by SEM, XPS and XRD. It was found that a micro-network structure with sizes of <200 nm mainly composed of bioactive sodium titanate and rutile phases of TiO2 covered the interior and exterior of porous titanium cells, and redundant Ca ion was detected in the titanate layer. The concentration distribution of Ti, O, Ca and Na in the coating showed a compositional gradient from the intermediate layer toward the outer surface. These compositional gradients indicate that the coating bonded to Ti substrate without a distinct interface. After immersion into the SBF solution for 3 days, a bone-like carbonate-hydroxylapatite showing a good biocompatibility was detected on the coating surface. And the redundant Ca advanced the bioactivity of the coating. Thus, the present modification is expected to allow the use of the bioactive porous titanium as artificial bones even under load-bearing conditions.

Formation mechanism and adhesive strength of a hydroxyapatite/TiO2 composite coating on a titanium surface prepared by micro-arc oxidation

NASA Astrophysics Data System (ADS)

Liu, Shimin; Li, Baoe; Liang, Chunyong; Wang, Hongshui; Qiao, Zhixia

2016-01-01

A hydroxyapatite (HA)/TiO2 composite coating was prepared on a titanium surface by one-step micro-arc oxidation (MAO). The formation mechanism of the composite coating was investigated and the adhesion of the coating to the substrate was also measured. The results showed that flocculent structures could be obtained during the early stages of treatment. As the treatment period extended, increasing amounts of Ca-P precipitate appeared on the surface, and the flocculent morphology transformed into a plate-like morphology. Then the plate-like calcium and phosphate salt self-assembled to form flower-like apatite. The Ca/P atomic ratio gradually decreased, indicating that the amounts of Ca2+ ions which diffused into the coating decreased more rapidly than that of PO43- or HPO42-. The adhesive strength between the apatite and TiO2 coating was improved. This improvement is attributed to the interlocking effect between the apatite and TiO2 layer which formed simultaneously during the early stages of the one-step MAO. This study shows that it is a promising method to prepare bioactive coating on a titanium surface.

The influence of gamma irradiation on natural dyeing properties of cotton and flax fabrics

NASA Astrophysics Data System (ADS)

Chirila, Laura; Popescu, Alina; Cutrubinis, Mihalis; Stanculescu, Ioana; Moise, Valentin Ioan

2018-04-01

Fabrics made of 100% cotton and 100% flax respectively were exposed at ambient temperature to gamma radiation doses, from 5 to 40 kGy, using a Co-60 research irradiator. After the irradiation treatment the fabrics were subjected to dyeing process with Itodye Nat Pomegranate commercial natural dye. The influence of gamma irradiation treatment on the physical-mechanical properties, dyeing and surface morphology of natural fibres were investigated. Gamma ray treatment of 40 kGy was the most effective in the case of fabrics made from 100% cotton, enhancing the colour strength as evidenced by K/S value. The results obtained from the mechanical properties of fabrics made of 100% flax indicated that the dose of 40 kGy leads to a decrease of tensile strength up of to 41.5%. Infrared spectroscopy was used to monitor chemical and structural changes in cellulosic fibres induced during processing. Crystallinity indices calculated from various bands ratio showed insignificant variations for cotton and small variations in the case of flax. The surface morphology of irradiated cotton fabrics did not show significant changes even at the highest dose of 40 kGy, while the low doses applied on flax fabrics led to an appearance of small changes of surface morphology. The gamma irradiation increased the uptake of natural dyes on natural cellulosic fibres.

Functionalized coatings by cold spray: An in vitro study of micro- and nanocrystalline hydroxyapatite compared to porous titanium.

PubMed

Vilardell, A M; Cinca, N; Garcia-Giralt, N; Dosta, S; Cano, I G; Nogués, X; Guilemany, J M

2018-06-01

Three different surface treatments on a Ti6Al4V alloy have been in vitro tested for possible application in cementless joint prosthesis. All of them involve the novelty of using the Cold Spray technology for their deposition: (i) an as-sprayed highly rough titanium and, followed by the deposition of a thin hydroxyapatite layer with (ii) microcrystalline or (iii) nanocrystalline structure. Primary human osteoblasts were extracted from knee and seeded onto the three different surfaces. Cell viability was tested by MTS and LIVE/DEAD assays, cell differentiation by alkaline phosphatase (ALP) quantification and cell morphology by Phalloidin staining. All tests were carried out at 1, 7 and 14 days of cell culture. Different cell morphologies between titanium and hydroxyapatite surfaces were exhibited. At 1 day of cell culture, cells on the titanium coating were spread and flattened, expanding the filopodia actin filaments in all directions, while cells on the hydroxyapatite coatings showed round like-shape morphology due to slower attachment. Higher cell viability was detected at all times of cell culture on titanium coating due to a better attachment at 1 day. However, from 7 days of cell culture, cells on hydroxyapatite showed good attachment onto surfaces and highly increased their proliferation, mostly on nanocrystalline, achieving similar cell viability levels than titanium coatings. ALP levels were significantly higher in titanium, in part, because of greatest cell number. Overall, the best cell functional results were obtained on titanium coatings whereas microcrystalline hydroxyapatite presented the worst cellular parameters. However, results indicate that nanocrystalline hydroxyapatite coatings may achieve promising results for the faster cell proliferation once cells are attached on the surface. Copyright © 2018 Elsevier B.V. All rights reserved.

Illuminating Low Surface Brightness Galaxies with the Hyper Suprime-Cam Survey

NASA Astrophysics Data System (ADS)

Greco, Johnny P.; Greene, Jenny E.; Strauss, Michael A.; Macarthur, Lauren A.; Flowers, Xzavier; Goulding, Andy D.; Huang, Song; Kim, Ji Hoon; Komiyama, Yutaka; Leauthaud, Alexie; Leisman, Lukas; Lupton, Robert H.; Sifón, Cristóbal; Wang, Shiang-Yu

2018-04-01

We present a catalog of extended low surface brightness galaxies (LSBGs) identified in the Wide layer of the Hyper Suprime-Cam Subaru Strategic Program (HSC-SSP). Using the first ∼200 deg2 of the survey, we have uncovered 781 LSBGs, spanning red (g ‑ i ≥ 0.64) and blue (g ‑ i < 0.64) colors and a wide range of morphologies. Since we focus on extended galaxies (r eff = 2.″5–14″), our sample is likely dominated by low-redshift objects. We define LSBGs to have mean surface brightnesses {\\bar{μ }}eff}(g)> 24.3 mag arcsec‑2, which allows nucleated galaxies into our sample. As a result, the central surface brightness distribution spans a wide range of μ 0(g) = 18–27.4 mag arcsec‑2, with 50% and 95% of galaxies fainter than 24.3 and 22 mag arcsec‑2, respectively. Furthermore, the surface brightness distribution is a strong function of color, with the red distribution being much broader and generally fainter than that of the blue LSBGs, and this trend shows a clear correlation with galaxy morphology. Red LSBGs typically have smooth light profiles that are well characterized by single-component Sérsic functions. In contrast, blue LSBGs tend to have irregular morphologies and show evidence for ongoing star formation. We cross-match our sample with existing optical, H I, and ultraviolet catalogs to gain insight into the physical nature of the LSBGs. We find that our sample is diverse, ranging from dwarf spheroidals and ultradiffuse galaxies in nearby groups to gas-rich irregulars to giant LSB spirals, demonstrating the potential of the HSC-SSP to provide a truly unprecedented view of the LSBG population.

Effect of Cu Alloying on S Poisoning of Ni Surfaces and Nanoparticle Morphologies Using Ab-Initio Thermodynamics Calculations.

PubMed

Kim, Ji-Su; Kim, Byung-Kook; Kim, Yeong-Cheol

2015-10-01

We investigated the effect of Cu alloying on S poisoning of Ni surfaces and nanoparticle morphologies using ab-initio thermodynamics calculations. Based on the Cu segregation energy and the S adsorption energy, the surface energy and nanoparticle morphology of pure Ni, pure Cu, and NiCu alloys were evaluated as functions of the chemical potential of S and the surface orientations of (100), (110), and (111). The constructed nanoparticle morphology was varied as a function of chemical potential of S. We find that the Cu added to Ni for NiCu alloys is strongly segregated into the top surface, and increases the S tolerance of the NiCu nanoparticles.

The effect of metallic oxide deposition on the electrochemical behaviour of Al-Zn-Mg-Sn alloy in natural tropical seawater

NASA Astrophysics Data System (ADS)

Din Yati, M. S.; Nazree Derman, Mohd; Isa, M. C.; Y Ahmad, M.; Yusoff, N. H. N.; Muhammad, M. M.; Nain, H.

2014-06-01

The potential of aluminium alloys as anode materials in cathodic protection system has been explored and a significant improvement has been achieved. However, for marine application, it is quite difficult to maintain continuous activation process due to passivation behavior of aluminum alloys. Therefore, to choose the best activation mechanism for aluminium alloy in marine environment, it has to be considered from various points such as alloy composition and surface treatment. This paper report the effect of metallic ruthenium oxide (RuO2) deposition on the surface of as-cast Al-Zn-Mg-Sn alloy and to study the effect of its presence on the electrochemical behavior using direct current (DC) electrochemical polarization and current capacity measurement. The morphology and topography of corroded surface were studied by the aid of scanning electron microscope (SEM) and confocal laser scanning microscope (CLSM) respectively. Results from this study showed that the presence of intermetallic compound (Mg2Sn) and also mixed metal oxide compound (Al2O3 and RuO2) on the alloy surface has been very useful in improving electrochemical reaction and charge transfer activities in chloride containing solution. This study also showed that RuO2 catalytic coating applied on the surface of Al-Zn-Mg-Sn alloy has slightly increased the corrosion current density compared to Al-Zn-Mg-Sn without RuO2. The corrosion morphology and topography of corroded surface of Al-Zn-Mg-Sn alloy deposited with RuO2 was found more uniform corrosion attack with the formation of porous and fibrous mud-like crack on outer layer. Based on surface morphology and 3D topographic studies, these features were believed to facilitate ionic species adsorption and diffusion through corrosion product layer at solution-alloy interface. Deposited RuO2 films also was found to increase of current efficiency by more than 10%.

Analytical Modeling for Mechanical Strength Prediction with Raman Spectroscopy and Fractured Surface Morphology of Novel Coconut Shell Powder Reinforced: Epoxy Composites

NASA Astrophysics Data System (ADS)

Singh, Savita; Singh, Alok; Sharma, Sudhir Kumar

2017-06-01

In this paper, an analytical modeling and prediction of tensile and flexural strength of three dimensional micro-scaled novel coconut shell powder (CSP) reinforced epoxy polymer composites have been reported. The novel CSP has a specific mixing ratio of different coconut shell particle size. A comparison is made between obtained experimental strength and modified Guth model. The result shows a strong evidence for non-validation of modified Guth model for strength prediction. Consequently, a constitutive modeled equation named Singh model has been developed to predict the tensile and flexural strength of this novel CSP reinforced epoxy composite. Moreover, high resolution Raman spectrum shows that 40 % CSP reinforced epoxy composite has high dielectric constant to become an alternative material for capacitance whereas fractured surface morphology revealed that a strong bonding between novel CSP and epoxy polymer for the application as light weight composite materials in engineering.

Effect of deposition parameters on the structural properties of ZnO nanopowders prepared by microwave-assisted hydrothermal synthesis.

PubMed

Caglar, Yasemin; Gorgun, Kamuran; Aksoy, Seval

2015-03-05

ZnO nanopowders were synthesized via microwave-assisted hydrothermal method at different deposition (microwave irradiation) times and pH values. The effects of pH and deposition (microwave irradiation) time on the crystalline structure and orientation of the ZnO nanopowders have been investigated by X-ray diffraction (XRD) study. XRD observations showed that the crystalline quality of ZnO nanopowders increased with increasing pH value. The crystallite size and texture coefficient values of ZnO nanopowders were calculated. The structural quality of ZnO nanopowder was improved by deposition parameters. Field emission scanning electron microscope (FESEM) was used to analyze the surface morphology of the ZnO nanopowders. Microwave irradiation time and pH value showed a significant effect on the surface morphology. Copyright © 2014 Elsevier B.V. All rights reserved.

Influence of Synthesis Temperature on the Growth and Surface Morphology of Co₃O₄ Nanocubes for Supercapacitor Applications.

PubMed

Samal, Rashmirekha; Dash, Barsha; Sarangi, Chinmaya Kumar; Sanjay, Kali; Subbaiah, Tondepu; Senanayake, Gamini; Minakshi, Manickam

2017-10-31

A facile hydrothermal route to control the crystal growth on the synthesis of Co₃O₄ nanostructures with cube-like morphologies has been reported and tested its suitability for supercapacitor applications. The chemical composition and morphologies of the as-prepared Co₃O₄ nanoparticles were extensively characterized using X-ray diffraction (XRD) and transmission electron microscopy (TEM). Varying the temperature caused considerable changes in the morphology, the electrochemical performance increased with rising temperature, and the redox reactions become more reversible. The results showed that the Co₃O₄ synthesized at a higher temperature (180 °C) demonstrated a high specific capacitance of 833 F/g. This is attributed to the optimal temperature and the controlled growth of nanocubes.

Surface modification of LiNbO3 and KTa1-xNbxO3 crystals irradiated by intense pulsed ion beam

NASA Astrophysics Data System (ADS)

Cui, Xiaojun; Shen, Jie; Zhong, Haowen; Zhang, Jie; Yu, Xiao; Liang, Guoying; Qu, Miao; Yan, Sha; Zhang, Xiaofu; Le, Xiaoyun

2017-10-01

In this work, we studied the surface modification of LiNbO3 and KTa1-xNbxO3 irradiated by intense pulsed ion beam, which was mainly composed of H+ (70%) and Cn+ (30%) at an acceleration voltage of about 450 kV. The surface morphologies, microstructural evolution and elemental analysis of the sample surfaces after IPIB irradiation have been analyzed by scanning electron microscope, atomic force microscope, X-ray diffraction and energy dispersive spectrometer techniques, respectively. The results show that the surface morphologies have significant difference impacted by the irradiation effect. Regular gully damages range from 200 to 400 nm in depth appeared in LiNbO3 under 2 J/cm2 energy density for 1 pulse, block cracking appeared in KTa1-xNbxO3 at the same condition. Surface of the crystals have melted and were darkened with the increasing number up to 5 pulses. Crystal lattice arrangement is believed to be the dominant reason for the different experimental results irradiated by intense pulsed ion beam.

Morphology and inhibition performance of Ag thin film as antimicrobial coating deposited by RF-PVD on 316 L stainless steel

NASA Astrophysics Data System (ADS)

Purniawan, A.; Khrisna, Y. S. A.; Rasyida, A.; Atmono, T. M.

2018-04-01

Foreign body related infection (FBRIs) is caused by forming biofilm of bacterial colony of medical equipment surfaces. In many cases, the FBRIs is still happened on the surface after medical sterilization process has been performed. In order to avoid the case, surface modification by antimicrobial coating was used. In this work, we present silver (Ag) thin film on 316 L stainless steel substrate surface was deposited using Radio Frequency Sputtering PVD (RF-PVD). The morphology of Ag thin film were characterized using SEM-EDX. Surface roughness of the thin film was measured by AFM. In addition, Kirby Bauer Test in Escherichia coli (E. coli) was conducted in order to evaluate the inhibition performance of the Ag thin film antimicrobial coating. Based on SEM and AFM results show that the particle size is increased from 523 nm to 708 nm and surface roughness from 9 to 20 nm for deposition time 10 minutes to 20 minutes, respectively. In addition, the inhibition layer of the coating is about 29 mm.

Investigation on Selective Laser Melting AlSi10Mg Cellular Lattice Strut: Molten Pool Morphology, Surface Roughness and Dimensional Accuracy

PubMed Central

Han, Xuesong; Zhu, Haihong; Nie, Xiaojia; Wang, Guoqing; Zeng, Xiaoyan

2018-01-01

AlSi10Mg inclined struts with angle of 45° were fabricated by selective laser melting (SLM) using different scanning speed and hatch spacing to gain insight into the evolution of the molten pool morphology, surface roughness, and dimensional accuracy. The results show that the average width and depth of the molten pool, the lower surface roughness and dimensional deviation decrease with the increase of scanning speed and hatch spacing. The upper surface roughness is found to be almost constant under different processing parameters. The width and depth of the molten pool on powder-supported zone are larger than that of the molten pool on the solid-supported zone, while the width changes more significantly than that of depth. However, if the scanning speed is high enough, the width and depth of the molten pool and the lower surface roughness almost keep constant as the density is still high. Therefore, high dimensional accuracy and density as well as good surface quality can be achieved simultaneously by using high scanning speed during SLMed cellular lattice strut. PMID:29518900

Growth morphology of CL-20/HMX cocrystal explosive: insights from solvent behavior under different temperatures.

PubMed

Han, Gang; Li, Qi-Fa; Gou, Rui-Jun; Zhang, Shu-Hai; Ren, Fu-de; Wang, Li; Guan, Rong

2017-11-28

A 2,4,6,8,10,12-hexanitro-2,4,6,8,10,12-hexaazaisowurtzitane (CL-20) /1,3,5,7-tetranitro-1,3,5,7-tetrazacyclooctane (HMX)-isopropanol (IPA) interfacial model was constructed to investigate the effect of temperature on cocrystal morphology. A constant volume and temperature molecular dynamics (NVT-MD) simulation was performed on the interfacial model at various temperatures (295-355 K, 20 K intervals). The surface electrostatic potential (ESP) of the CL-20/HMX cocrystal structure and IPA molecule were studied by the B3LYP method at 6-311++G (d, p) level. The surface energies, polarities, adsorption energy, mass density distribution, radial distribution function (RDF), mean square displacement (MSD) and relative changes of attachment energy were analyzed. The results show that polarities of (1 0 0) and (0 1 1) cocrystal surfaces may be more negative and affected by IPA solvent. The adsorption energy per area indicates that growth of the (1 0-2) face in IPA conditions may be more limited, while the (1 0 0) face tends to grow more freely. MSD and diffusion coefficient (D) analyses demonstrated that IPA molecules gather more easily on the cocrystal surface at lower temperatures, and hence have a larger effect on the growth of cocrystal faces. RDF analysis shows that, with the increasing of temperature, the strength of hydrogen bond interactions between cocrystal and solvent becomes stronger, being highest at 335 K for the (1 0 0) and (0 1 1) interfacial models. Results of relative changes of modified attachment energy show that (1 0 0) and (0 1 1) faces tends to be larger than other faces. Moreover, the predicted morphologies at 295 and 355 K are consistent with experimental values, proving that the CL-20/HMX-IPA interfacial model is a reasonable one for this study. Graphical Abstract Construction of 2,4,6,8,10,12-hexanitro-2,4,6,8,10,12-hexaazaisowurtzitane (CL-20) /1,3,5,7-tetranitro-1,3,5,7-tetrazacyclooctane (HMX)-isopropanol (IPA) interfacial model, analysis, and morphology prediction of cocrystal.

The Influence of Crustal Thickness and Slope on the Surface Morphology of Active Lava Flows: an Experimental Approach

NASA Astrophysics Data System (ADS)

Applegarth, L. J.; James, M. R.; van Wyk de Vries, B.; Pinkerton, H.

2007-12-01

Many of the surface features that develop on `a`a and blocky lava flows relate to internal dynamics during flow emplacement, but it can be difficult to infer the precise relationships between morphology and dynamics from observations of flows either during or after their emplacement. Experiments using PEG have greatly improved our understanding of the behaviour of lavas with relatively thin crusts. Here we describe an alternative approach (similar to that of Lescinsky and Merle (2005), GSA Special Paper 396, p.136) in which the crust plays a significant role in flow development. Our experiments investigated the effect of crustal thickness and slope on the morphological development of channelised distal flows. The materials used were high viscosity (104 Pa s) silicone gel to simulate the still-fluid lava, and a mix of sand and plaster to represent the cohesive brittle crust and the confining levees. Experiments were conducted on an inclined board with a reservoir constructed at one end. Silicone was released from the reservoir through a sliding gate, where it encountered a seed flow consisting of a silicone sheet topped with a crust of known depth and constrained by levees. The models therefore represented the influx of fresh lava into a channel. Sequential digital images taken over the course of each experiment allowed marker points on the flow surface to be tracked, and these data were used to construct surface velocity maps. Several experiments were recorded using stereo imagery, allowing changes in the surface relief to be monitored. The insights from these quantitative techniques, combined with morphological observations, are used to illustrate the effect of the crust on the flow dynamics, and to show the response of the brittle crust to the movement of the viscous flow interior. An overview of the experimental techniques and results will be presented, together with an assessment of how the observed model morphologies can be related to features observed in the field.

Design and characterization of textured surfaces for applications in the food industry

NASA Astrophysics Data System (ADS)

Lazzini, G.; Romoli, L.; Blunt, L.; Gemini, L.

2017-12-01

The aim of this work is to design, manufacture and characterize surface morphologies on AISI 316L stainless steel produced by a custom designed laser-texturing strategy. Surface textures were characterized at a micrometric dimension in terms of areal parameters compliant with ISO 25178, and correlations between these parameters and processing parameters (e.g. laser energy dose supplied to the material, repetition rate of the laser pulses and scanning velocity) were investigated. Preliminary efforts were devoted to the research of special requirements for surface morphology that, according to the commonly accepted research on the influence of surface roughness on cellular adhesion on surfaces, should discourage the formation of biofilms. The topographical characterization of the surfaces was performed with a coherence scanning interferometer. This approach showed that increasing doses of energy to the surfaces increased the global level of roughness as well as the surface complexity. Moreover, the behavior of the parameters S pk, S vk also indicates that, due to the ablation process, an increase in the energy dose causes an average increase in the height of the highest peaks and in the depth of the deepest dales. The study of the density of peaks S pd showed that none of the surfaces analyzed here seem to perfectly match the conditions dictated by the theories on cellular adhesion to confer anti-biofouling properties. However, this result seems to be mainly due to the limits of the resolving power of coherence scanning interferometry, which does not allow the resolution of sub-micrometric features which could be crucial in the prevention of cellular attachment.

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.

Laser processing of metallic biomaterials: An approach for surface patterning and wettability control

NASA Astrophysics Data System (ADS)

Razi, Sepehr; Mollabashi, Mahmoud; Madanipour, Khosro

2015-12-01

Q -switched Nd:YAG laser is used to manipulate the surface morphology and wettability characteristic of 316L stainless steel (SS) and titanium biomaterials. Water and glycerol are selected as wettability testing liquids and the sessile drop method is used for the contact angle measurements. Results indicate that on both of the metals, wettability toward water improves significantly after the laser treatment. Different analyses including the study of the surface morphology, free energy and oxidation are assessed in correlation with wettability. Beside the important role of the laser-induced surface patterns, the increase in the surface roughness, oxygen content and the polar component of the surface energy, are detected as the most important physical and chemical phenomena controlling the improvement in the wettability. However, all the processed hydrophilic surfaces that are exposed to air become hydrophobic over time. The time dependency of the surface wettability is related to the chemical activities on the treated surfaces and the reduction of oxygen/carbon (O/C) ratio on them. The behavior is further studied with investigating the effect of the keeping environment and changes of the components of the surface tension. Results show that the pulsed laser treatment is a versatile approach to create either hydrophobic or super hydrophilic surfaces for industrial and medical applications.

Surface compositional variation on the comet 67P/Churyumov-Gerasimenko by OSIRIS data

NASA Astrophysics Data System (ADS)

Barucci, M. A.; Fornasier, S.; Feller, C.; Perna, D.; Hasselmann, H.; Deshapriya, J. D. P.; Fulchignoni, M.; Besse, S.; Sierks, H.; Forgia, F.; Lazzarin, M.; Pommerol, A.; Oklay, N.; Lara, L.; Scholten, F.; Preusker, F.; Leyrat, C.; Pajola, M.; Osiris-Rosetta Team

2015-10-01

Since the Rosetta mission arrived at the comet 67P/Churyumov-Gerasimenko (67/P C-G) on July 2014, the comet nucleus has been mapped by both OSIRIS (Optical, Spectroscopic, and Infrared Remote Imaging System, [1]) NAC (Narrow Angle Camera) and WAC (Wide Angle Camera) acquiring a huge quantity of surface's images at different wavelength bands, under variable illumination conditions and spatial resolution, and producing the most detailed maps at the highest spatial resolution of a comet nucleus surface.67/P C-G's nucleus shows an irregular bi-lobed shape of complex morphology with terrains showing intricate features [2, 3] and a heterogeneity surface at different scales.

Solvent-vapor-assisted dewetting of prepatterned thin polymer films: control of morphology, order, and pattern miniaturization.

PubMed

Bhandaru, Nandini; Goohpattader, Partho Sarathi; Faruqui, Danish; Mukherjee, Rabibrata; Sharma, Ashutosh

2015-03-17

Ultrathin (<100 nm) unstable polymer films exposed to a solvent vapor dewet by the growth of surface instability, the wavelength (λ) of which depends on the film thickness (h(f)). While the dewetting of a flat polymer thin film results in random structures, we show that the dewetting of a prepatterned film results in myriad ordered mesoscale morphologies under specific conditions. Such a film undergoes rupture over the thinnest parts when the initial local thickness of these zones (h(rm)) is lower than a limiting thickness h(lim) ≈ 10 nm. Additionally, the width of the pattern grooves (l(s)) must be wider than λ(s) corresponding to a flat film having a thickness of h(rm) for pattern-directed dewetting to take place over surface-tension-induced flattening. We first present an experimentally obtained morphology phase diagram that captures the conditions where a transition from surface-tension-induced flattening to pattern-directed-rupture takes place. Subsequently, we show the versatility of this technique in achieving a variety of aligned mesopatterns starting from a prepatterned film with simple grating geometry. The morphology of the evolving patterns depends on several parameters such as the initial film thickness (h(f)), prepattern amplitude (h(st)), duration of solvent vapor exposure (SVE), and wettability of the stamp used for patterning. Periodic rupture of the film at regular intervals imposes directionality on the evolving patterns, resulting in isolated long threads/cylindrical ridges of polymers, which subsequently disintegrate into an aligned array of droplets due to Rayleigh-Plateau instability under specific conditions. Other patterns such as a double periodic array of droplets and an array of holes are also possible to obtain. The evolution can be interrupted at any intermediate stage by terminating the solvent vapor annealing, allowing the creation of pattern morphology on demand. The created patterns are significantly miniaturized in size as compared to features obtained from dewetting a flat film with the same hf.

Comparative study on morphologic changes and cell attachment of periodontitis-affected root surfaces following conditioning with CO2 and Er:YAG laser irradiations.

PubMed

Belal, Mahmoud Helmy; Watanabe, Hisashi

2014-10-01

Clinical application of lasers in periodontal therapy has continued to expand in last decades; however there are still some controversies. The present study aimed to compare the conditioning effects of the carbon dioxide (CO2) or erbium-doped: yttrium, aluminum and garnet (Er:YAG) laser on periodontally diseased root surfaces following scaling and root planing (SRP) in terms of the alteration of morphologies as well as the attachment of periodontal ligament cells. Forty-five periodontally affected root specimens were prepared and randomly assigned into three groups: I control (untreated diseased), II. SRP+CO2 laser (pulsed, noncontact mode), and III. SRP+Er:YAG laser (slight contact mode). After treatment, five specimens in each group were used for surface topographic examination. The remaining 10 specimens in each group were incubated with human periodontal ligament cell suspension. All the specimens were finally evaluated by scanning electron microscopy. The control specimens showed the lowest number of cultured cells, mostly in oval shape, with no tightly attached cells. The CO2 lased specimens showed a significant increase in the number of attached cells compared with controls, but demonstrated some major thermal alterations on the surfaces. The Er:YAG lased specimens showed the significantly highest number of attached cells, mostly in flat form, and did not show distinct thermal damage. The present study suggests that compared with the CO2 laser, the Er:YAG laser may constitute a more useful conditioning tool for enhancing periodontal cell attachment to periodontally diseased root surfaces, with fewer undesirable thermal side effects.

Optimizing ultrathin Ag films for high performance oxide-metal-oxide flexible transparent electrodes through surface energy modulation and template-stripping procedures

PubMed Central

Yang, Xi; Gao, Pingqi; Yang, Zhenhai; Zhu, Juye; Huang, Feng; Ye, Jichun

2017-01-01

Among new flexible transparent conductive electrode (TCE) candidates, ultrathin Ag film (UTAF) is attractive for its extremely low resistance and relatively high transparency. However, the performances of UTAF based TCEs critically depend on the threshold thickness for growth of continuous Ag films and the film morphologies. Here, we demonstrate that these two parameters could be strongly altered through the modulation of substrate surface energy. By minimizing the surface energy difference between the Ag film and substrate, a 9 nm UTAF with a sheet resistance down to 6.9 Ω sq−1 can be obtained using an electron-beam evaporation process. The resultant UTAF is completely continuous and exhibits smoother morphologies and smaller optical absorbances in comparison to the counterpart of granular-type Ag film at the same thickness without surface modulation. Template-stripping procedure is further developed to transfer the UTAFs to flexible polymer matrixes and construct Al2O3/Ag/MoOx (AAM) electrodes with excellent surface morphology as well as optical and electronic characteristics, including a root-mean-square roughness below 0.21 nm, a transparency up to 93.85% at 550 nm and a sheet resistance as low as 7.39 Ω sq−1. These AAM based electrodes also show superiority in mechanical robustness, thermal oxidation stability and shape memory property. PMID:28291229

Optimizing ultrathin Ag films for high performance oxide-metal-oxide flexible transparent electrodes through surface energy modulation and template-stripping procedures

NASA Astrophysics Data System (ADS)

Yang, Xi; Gao, Pingqi; Yang, Zhenhai; Zhu, Juye; Huang, Feng; Ye, Jichun

2017-03-01

Among new flexible transparent conductive electrode (TCE) candidates, ultrathin Ag film (UTAF) is attractive for its extremely low resistance and relatively high transparency. However, the performances of UTAF based TCEs critically depend on the threshold thickness for growth of continuous Ag films and the film morphologies. Here, we demonstrate that these two parameters could be strongly altered through the modulation of substrate surface energy. By minimizing the surface energy difference between the Ag film and substrate, a 9 nm UTAF with a sheet resistance down to 6.9 Ω sq-1 can be obtained using an electron-beam evaporation process. The resultant UTAF is completely continuous and exhibits smoother morphologies and smaller optical absorbances in comparison to the counterpart of granular-type Ag film at the same thickness without surface modulation. Template-stripping procedure is further developed to transfer the UTAFs to flexible polymer matrixes and construct Al2O3/Ag/MoOx (AAM) electrodes with excellent surface morphology as well as optical and electronic characteristics, including a root-mean-square roughness below 0.21 nm, a transparency up to 93.85% at 550 nm and a sheet resistance as low as 7.39 Ω sq-1. These AAM based electrodes also show superiority in mechanical robustness, thermal oxidation stability and shape memory property.

Nanofibers grafted on titanium alloy: the effects of fiber alignment and density on osteoblast mineralization.

PubMed

Lin, Hsin-Yi; Peng, Zhao-Xiang

2017-08-17

The surface of medical implant alloy Ti-6Al-4V was chemically modified to allow it to covalently bond with collagen/PVA nanofibers. These nanofibers were successfully attached to the Ti-6Al-4V surface in three different morphologies: randomly oriented high-density fiber, COL(H); randomly oriented low-density fiber, COL(L); and aligned high-density fiber, COL(A). The effects of the morphology of these covalently-bound collagen nanofibers on the growth and differentiation of osteoblasts were studied for 21 days. The low-density nanofibers covered approximately 80% of the Ti64 surface, while the high-density nanofibers covered nearly 100%. These covalently attached fibrous coatings remained attached to the metal surface after 3 weeks of cell culture. In the first week the aligned fibers of COL(A) allowed the osteoblasts to stretch and elongate in the direction of the fibers. This directional elongation was not seen in the cells on the randomly-oriented samples. Cells proliferated and differentiated on all three surfaces over time. By the end of the test, the amount of type I collagen secreted by the cells on COL(H) was the highest, while the degree of mineralization was highest on COL(A) among the three samples (p < 0.05). Different nanofiber morphologies changed the cell morphology and the secretion of cellular products. The mechanisms remained to be investigated. The surface of medical implant alloy Ti-6Al-4V was chemically modified to allow it to covalently bond with collagen/PVA nanofibers. The SEM micrographs in the top row show the random and aligned morphology of the collagen-PVA nanofibers. The nanofibers on COL(A) were aligned in the general direction indicated by the arrow. The second row are images from EDX titanium element mapping. The location of the titanium elements are shown as bright dots. The low-density nanofibers, COL(L), covered approximately 80% of the Ti64 surface, while the high-density nanofibers, COL(H) and COL(A), covered nearly 100%. All three surfaces demonstrated good biocompatibility for the cultured osteoblasts. The fiber alignment seemed to have an effect on early cellular morphology (day 7), collagen secretion and calcium deposition, while the density of the fibers seemed to have no significant effect on cell behavior. SEM micrographs of osteoblasts after 7 and 14 days of cell culture are shown in the third and fourth rows. The surface of COL(L) has more cell-free spots indicated by (*) on day 7 as other two surfaces were covered by cells. The nanofibers could no longer be observed and were covered with mineralized granules (circles) after 14 days of cell culture. The cells appear stretched out on the mineralized granules.

Tuning the Morphology of Li2O2 by Noble and 3d metals: A Planar Model Electrode Study for Li-O2 Battery.

PubMed

Yang, Yao; Liu, Wei; Wu, Nian; Wang, Xiaochen; Zhang, Tao; Chen, Linfeng; Zeng, Rui; Wang, Yingming; Lu, Juntao; Fu, Lei; Xiao, Li; Zhuang, Lin

2017-06-14

In this work, a planar model electrode method has been used to investigate the structure-activity relationship of multiple noble and 3d metal catalysts for the cathode reaction of Li-O 2 battery. The result shows that the battery performance (discharge/charge overpotential) strongly depends not only on the type of catalysts but also on the morphology of the discharge product (Li 2 O 2 ). Specifically, according to electrochemical characterization and scanning electron microscopy (SEM) observation, noble metals (Pd, Pt, Ru, Ir, and Au) show excellent battery performance (smaller discharge/charge overpotential), with wormlike Li 2 O 2 particles with size less than 200 nm on their surfaces. On the other hand, 3d metals (Fe, Co, Ni, and Mn) offered poor battery performance (larger discharge/charge overpotential), with much larger Li 2 O 2 particles (1 μm to a few microns) on their surfaces after discharging. Further research shows that a "volcano plot" is found by correlating the discharging/charging plateau voltage with the adsorption energy of LiO 2 on different metals. The metals with better battery performance and worm-like-shaped Li 2 O 2 are closer to the top of the "volcano", indicating adsorption energy of LiO 2 is one of the key characters for the catalyst to reach a good performance for the oxygen electrode of Li-O 2 battery, and it has a strong influence on the morphology of the discharge product on the electrode surface.

Brain Morphology Links Systemic Inflammation to Cognitive Function in Midlife Adults

PubMed Central

Marsland, Anna L.; Gianaros, Peter J.; Kuan, Dora C-H.; Sheu, Lei K.; Krajina, Katarina; Manuck, Stephen B.

2015-01-01

Background Inflammation is linked to cognitive decline in midlife, but the neural basis for this link is unclear. One possibility is that inflammation associates with adverse changes in brain morphology, which accelerates cognitive aging and later dementia risk. Clear evidence is lacking, however, regarding whether inflammation relates to cognition in midlife via changes in brain morphology. Accordingly, the current study examines whether associations of inflammation with cognitive function are mediated by variation in cortical gray matter volume among midlife adults. Methods Plasma levels of interleukin (IL)-6 and C-reactive protein (CRP), relatively stable markers of peripheral systemic inflammation, were assessed in 408 community volunteers aged 30–54 years. All participants underwent structural neuroimaging to assess global and regional brain morphology and completed neuropsychological tests sensitive to early changes in cognitive function. Measurements of brain morphology (regional tissue volumes and cortical thickness and surface area) were derived using Freesurfer. Results Higher peripheral inflammation was associated with poorer spatial reasoning, short term memory, verbal proficiency, learning and memory, and executive function, as well as lower cortical gray and white matter volumes, hippocampal volume and cortical surface area. Mediation models with age, sex and intracranial volume as covariates showed cortical gray matter volume to partially mediate the association of inflammation with cognitive performance. Exploratory analyses of body mass suggested that adiposity may be a source of the inflammation linking brain morphology to cognition. Conclusions Inflammation and adiposity might relate to cognitive decline via influences on brain morphology. PMID:25882911

Carbon foam/hydroxyapatite coating for carbon/carbon composites: Microstructure and biocompatibility

NASA Astrophysics Data System (ADS)

Zhang, Leilei; Li, Hejun; Li, Kezhi; Zhang, Shouyang; Lu, Jinhua; Li, Wei; Cao, Sheng; Wang, Bin

2013-12-01

To improve the surface biocompatibility of carbon/carbon composites, a carbon foam/hydroxyapatite coating was applied using a combination method of slurry procedure and ultrasound-assisted electrochemical deposition procedure. The morphology, microstructure and chemical composition of the coating were investigated by scanning electron microscopy, energy dispersive X-ray spectroscopy, Fourier transform infrared spectroscopy, Raman spectroscopy and X-ray diffraction. The biocompatibility of the carbon foam/hydroxyapatite coating was investigated by osteoblast-like MG63 cell culture tests. The results showed that the carbon foam could provide a large number of pores on the surface of carbon/carbon composites. The hydroxyapatite crystals could infiltrate into the pores and form the carbon foam/hydroxyapatite coating. The coating covered the carbon/carbon composites fully and uniformly with slice morphology. The cell response tests showed that the MG63 cells on carbon foam/hydroxyapatite coating had a better cell adhesion and cell proliferation than those on uncoated carbon/carbon composites. The carbon foam/hydroxyapatite coatings were cytocompatible and were beneficial to improve the biocompatibility. The approach presented here may be exploited for fabrication of carbon/carbon composite implant surfaces.

Influence of Under-layer Morphology on Structural and Magnetic Properties of Sputtered Co81Pd19 Films

NASA Astrophysics Data System (ADS)

Ponchaiya, Pairin; Rattanasakulthong, Watcharee

2017-09-01

Sputtered Co81Pd19 films with thickness of about 60 nm were deposited on various under-layers (Co, Ni, Cr and Al) and on glass substrate. Structural, morphological and magnetic properties of Co81Pd19 films were investigated. All of prepared Co81Pd19 film showed CoPd-FCC phase in (111) direction on CoO-FCC (111), NiO-FCC (200), Cr-BCC (200) and (201) and AlO-FCC (200) phases of Co, Ni, Cr and Al under-layer, respectively. AFM images revealed that the film on Cr under-layers and glass substrate exhibited the maximum roughness with the highest grain size and the minimum roughness with the continuous grain size, respectively. Both parallel and perpendicular maximum coercive field were found in the film on glass under-layer and the film on Co-under-layer film showed the highest saturation magnetization from both in-plane and out-of-plane measurements. These results confirmed that the structural and magnetic properties of sputtered Co81Pd19 films were affected by under-layer surface roughness and morphology by the virtue of particle size and distribution on the under-layer film surface.

Step Permeability on the Pt(111) Surface

NASA Astrophysics Data System (ADS)

Altman, Michael

2005-03-01

Surface morphology will be affected, or even dictated, by kinetic limitations that may be present during growth. Asymmetric step attachment is recognized to be an important and possibly common cause of morphological growth instabilities. However, the impact of this kinetic limitation on growth morphology may be hindered by other factors such as the rate limiting step and step permeability. This strongly motivates experimental measurements of these quantities in real systems. Using low energy electron microscopy, we have measured step flow velocities in growth on the Pt(111) surface. The dependence of step velocity upon adjacent terrace width clearly shows evidence of asymmetric step attachment and step permeability. Step velocity is modeled by solving the diffusion equation simultaneously on several adjacent terraces subject to boundary conditions at intervening steps that include asymmetric step attachment and step permeability. This analysis allows a quantitative evaluation of step permeability and the kinetic length, which characterizes the rate limiting step continuously between diffusion and attachment-detachment limited regimes. This work provides information that is greatly needed to set physical bounds on the parameters that are used in theoretical treatments of growth. The observation that steps are permeable even on a simple metal surface should also stimulate more experimental measurements and theoretical treatments of this effect.

Multicompartmental Microcapsules from Star Copolymer Micelles

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

Choi, Ikjun; Malak, Sidney T.; Xu, Weinan

2013-02-26

We present the layer-by-layer (LbL) assembly of amphiphilic heteroarm pH-sensitive star-shaped polystyrene-poly(2-pyridine) (PSnP2VPn) block copolymers to fabricate porous and multicompartmental microcapsules. Pyridine-containing star molecules forming a hydrophobic core/hydrophilic corona unimolecular micelle in acidic solution (pH 3) were alternately deposited with oppositely charged linear sulfonated polystyrene (PSS), yielding microcapsules with LbL shells containing hydrophobic micelles. The surface morphology and internal nanopore structure of the hollow microcapsules were comparatively investigated for shells formed from star polymers with a different numbers of arms (9 versus 22) and varied shell thickness (5, 8, and 11 bilayers). The successful integration of star unimers into themore » LbL shells was demonstrated by probing their buildup, surface segregation behavior, and porosity. The larger arm star copolymer (22 arms) with stretched conformation showed a higher increment in shell thickness due to the effective ionic complexation whereas a compact, uniform grainy morphology was observed regardless of the number of deposition cycles and arm numbers. Small-angle neutron scattering (SANS) revealed that microcapsules with hydrophobic domains showed different fractal properties depending upon the number of bilayers with a surface fractal morphology observed for the thinnest shells and a mass fractal morphology for the completed shells formed with the larger number of bilayers. Moreover, SANS provides support for the presence of relatively large pores (about 25 nm across) for the thinnest shells as suggested from permeability experiments. The formation of robust microcapsules with nanoporous shells composed of a hydrophilic polyelectrolyte with a densely packed hydrophobic core based on star amphiphiles represents an intriguing and novel case of compartmentalized microcapsules with an ability to simultaneously store different hydrophilic, charged, and hydrophobic components within shells.« less

Structural characterization of cup-stacked-type nanofibers with an entirely hollow core

NASA Astrophysics Data System (ADS)

Endo, M.; Kim, Y. A.; Hayashi, T.; Fukai, Y.; Oshida, K.; Terrones, M.; Yanagisawa, T.; Higaki, S.; Dresselhaus, M. S.

2002-02-01

Straight long carbon nanofibers with a large hollow core obtained by a floating reactant method show a stacking morphology of truncated conical graphene layers, which in turn exhibit a large portion of open edges on the outer surface and also in the inner channels. Through a judicious choice of oxidation conditions, nanofibers with increased active edge sites are obtained without disrupting the fiber's morphology. A graphitization process induces a morphological change from a tubular type to a reversing saw-toothed type and the formation of loops along the inner channel of the nanofibers, accompanied by a decrease in interlayer spacing.

Morphological effects on the selectivity of intramolecular versus intermolecular catalytic reaction on Au nanoparticles.

PubMed

Wang, Dan; Sun, Yuanmiao; Sun, Yinghui; Huang, Jing; Liang, Zhiqiang; Li, Shuzhou; Jiang, Lin

2017-06-14

It is hard for metal nanoparticle catalysts to control the selectivity of a catalytic reaction in a simple process. In this work, we obtain active Au nanoparticle catalysts with high selectivity for the hydrogenation reaction of aromatic nitro compounds, by simply employing spine-like Au nanoparticles. The density functional theory (DFT) calculations further elucidate that the morphological effect on thermal selectivity control is an internal key parameter to modulate the nitro hydrogenation process on the surface of Au spines. These results show that controlled morphological effects may play an important role in catalysis reactions of noble metal NPs with high selectivity.

Modeling the characteristic etch morphologies along specific crystallographic orientations by anisotropic chemical etching

NASA Astrophysics Data System (ADS)

Li, Kun-Dar; Miao, Jin-Ru

2018-02-01

To improve the advanced manufacturing technology for functional materials, a sophisticated control of chemical etching process is highly demanded, especially in the fields of environment and energy related applications. In this study, a phase-field-based model is utilized to investigate the etch morphologies influenced by the crystallographic characters during anisotropic chemical etching. Three types of etching modes are inspected theoretically, including the isotropic, <100> and <111> preferred oriented etchings. Owing to the specific etching behavior along the crystallographic directions, different characteristic surface structures are presented in the simulations, such as the pimple-like, pyramidal hillock and ridge-like morphologies. In addition, the processing parameters affecting the surface morphological formation and evolution are also examined systematically. According to the numerical results, the growth mechanism of surface morphology in a chemical etching is revealed distinctly. While the etching dynamics plays a dominant role on the surface formation, the characteristic surface morphologies corresponding to the preferred etching direction become more apparent. As the atomic diffusion turned into a determinative factor, a smoothened surface would appear, even under the anisotropic etching conditions. These simulation results provide fundamental information to enhance the development and application of anisotropic chemical etching techniques.

Physicochemical properties of calcium silicate-based formulations MTA Repair HP and MTA Vitalcem.

PubMed

Guimarães, Bruno Martini; Prati, Carlo; Duarte, Marco Antonio Hungaro; Bramante, Clovis Monteiro; Gandolfi, Maria Giovanna

2018-04-05

This study aimed to analyze the following physicochemical properties: radiopacity, final setting time, calcium release, pH change, solubility, water sorption, porosity, surface morphology, and apatite-forming ability of two calcium silicate-based materials. We tested MTA Repair HP and MTA Vitalcem in comparison with conventional MTA, analyzing radiopacity and final setting time. Water absorption, interconnected pores and apparent porosity were measured after 24-h immersion in deionized water at 37°C. Calcium and pH were tested up to 28 d in deionized water. We analyzed data using two-way ANOVA with Student-Newman-Keuls tests (p<0.05). We performed morphological and chemical analyses of the material surfaces using ESEM/EDX after 28 d in HBSS. MTA Repair HP showed similar radiopacity to that of conventional MTA. All materials showed a marked alkalinizing activity within 3 h, which continued for 28 d. MTA Repair HP showed the highest calcium release at 28 d (p<0.05). MTA Vitalcem showed statistically higher water sorption and solubility values (p<0.05). All materials showed the ability to nucleate calcium phosphate on their surface after 28 d in HBSS. MTA Repair HP and MTA Vitalcem had extended alkalinizing activity and calcium release that favored calcium phosphate nucleation. The presence of the plasticizer in MTA HP might increase its solubility and porosity. The radiopacifier calcium tungstate can be used to replace bismuth oxide.

Mechanical properties of NiTi and CuNiTi wires used in orthodontic treatment. Part 2: Microscopic surface appraisal and metallurgical characteristics

PubMed Central

Gravina, Marco Abdo; Canavarro, Cristiane; Elias, Carlos Nelson; Chaves, Maria das Graças Afonso Miranda; Brunharo, Ione Helena Vieira Portella; Quintão, Cátia Cardoso Abdo

2014-01-01

Objective This research aimed at comparing the qualitative chemical compositions and the surface morphology of fracture regions of eight types of Nickel (Ni) Titanium (Ti) conventional wires, superelastic and heat-activated (GAC, TP, Ormco, Masel, Morelli and Unitek), to the wires with addition of copper (CuNiTi 27ºC and 35ºC, Ormco) after traction test. Methods The analyses were performed in a scanning electronic microscope (JEOL, model JSM-5800 LV) with EDS system of microanalysis (energy dispersive spectroscopy). Results The results showed that NiTi wires presented Ni and Ti as the main elements of the alloy with minimum differences in their composition. The CuNiTi wires, however, presented Ni and Ti with a significant percentage of copper (Cu). As for surface morphology, the wires that presented the lowest wire-surface roughness were the superelastic ones by Masel and Morelli, while those that presented the greatest wire-surface roughness were the CuNiTi 27ºC and 35ºC ones by Ormco, due to presence of microcavity formed as a result of pulling out some particles, possibly of NiTi.4 The fracture surfaces presented characteristics of ductile fracture, with presence of microcavities. The superelastic wires by GAC and the CuNiTi 27ºC and the heat-activated ones by Unitek presented the smallest microcavities and the lowest wire-surface roughness with regard to fracture, while the CuNiTi 35ºC wires presented inadequate wire-surface roughness in the fracture region. Conclusion CuNiTi 35ºC wires did not present better morphologic characteristics in comparison to the other wires with regard to surfaces and fracture region. PMID:24713562

Sharp Morphological Transitions from Nanoscale Mixed-Anchoring Patterns in Confined Nematic Liquid Crystals

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

Armas-Pérez, Julio C.; Li, Xiao; Martínez-González, José A.

Liquid crystals are known to be particularly sensitive to orientational cues provided at surfaces or interfaces. In this work, we explore theoretically, computationally, and experimentally the behavior of liquid crystals on isolated nanoscale patterns with controlled anchoring characteristics at small length scales. The orientation of the liquid crystal is controlled through the use of chemically patterned polymer brushes that are tethered to a surface. This system can be engineered with remarkable precision, and the central question addressed here is whether a characteristic length scale exists at which information encoded on a surface is no longer registered by a liquid crystal.more » To do so, we adopt a tensorial description of the free energy of the hybrid liquidcrystal surface system, and we investigate its morphology in a systematic manner. For long and narrow surface stripes, it is found that the liquid crystal follows the instructions provided by the pattern down to 100 nm widths. This is accomplished through the creation of line defects that travel along the sides of the stripes. We show that a "sharp" morphological transition occurs from a uniform undistorted alignment to a dual uniform/splay-bend morphology. The theoretical and numerical predictions advanced here are confirmed by experimental observations. Our combined analysis suggests that nanoscale patterns can be used to manipulate the orientation of liquid crystals at a fraction of the energetic cost that is involved in traditional liquid crystal-based devices. The insights presented in this work have the potential to provide a new fabrication platform to assemble low power bistable devices, which could be reconfigured upon application of small external fields.« less

Coma Morphology Due to an Extended Active Region and Implications for the Spin State of Comet Hale-Bopp

NASA Technical Reports Server (NTRS)

Samarasinha, Nalin H.

2000-01-01

We show that the circular character of continuum structures observed in the coma of comet Hale-Bopp around the perihelion passage is most likely due to a dust jet from a large extended active region on the surface. Coma morphology due to a wide jet is different from that due to a narrow jet. The latter shows foreshortening effects due to observing geometry, wider jet produces more circular features. This circularization effect provides a self-consistent explanation for the evolution of near-perihelion coma morphology. No changes in the direction of the rotational angular momentum vector are required during this period in contrast to the models of Schleicher et al. This circularization effect also enables us to produce near-circular coma features in the S-E quadrant during 1997 late February and therefore questions the basic premise on which Sekanina bases his morphological arguments for a gravitationally bound satellite nucleus.

Role of carbon impurities on the surface morphology evolution of tungsten under high dose helium ion irradiation

NASA Astrophysics Data System (ADS)

Al-Ajlony, A.; Tripathi, J. K.; Hassanein, A.

2015-11-01

The effect of carbon impurities on the surface evolution (e.g., fuzz formation) of tungsten (W) surface during 300 eV He ions irradiation was studied. Several tungsten samples were irradiated by He ion beam with a various carbon ions percentage. The presence of minute carbon contamination within the He ion beam was found to be effective in preventing the fuzz formation. At higher carbon concentration, the W surface was found to be fully covered with a thick graphitic layer on the top of tungsten carbide (WC) layer that cover the sample surface. Lowering the ion beam carbon percentage was effective in a significant reduction in the thickness of the surface graphite layer. Under these conditions the W surface was also found to be immune for the fuzz formation. The effect of W fuzz prevention by the WC formation on the sample surface was more noticeable when the He ion beam had much lower carbon (C) ions content (0.01% C). In this case, the fuzz formation was prevented on the vast majority of the W sample surface, while W fuzz was found in limited and isolated areas. The W surface also shows good resistance to morphology evolution when bombarded by high flux of pure H ions at 900 °C.

Surface morphology of molybdenum silicide films upon low-energy ion beam sputtering

NASA Astrophysics Data System (ADS)

Gago, R.; Jaafar, M.; Palomares, F. J.

2018-07-01

The surface morphology of molybdenum silicide (Mo x Si1‑x ) films has been studied after low-energy Ar+ ion beam sputtering (IBS) to explore eventual pattern formation on compound targets and, simultaneously, gather information about the mechanisms behind silicide-assisted nanopatterning of silicon surfaces by IBS. For this purpose, Mo x Si1‑x films with compositions below, equal and above the MoSi2 stoichiometry (x  =  0.33) have been produced by magnetron sputtering, as assessed by Rutherford backscattering spectrometry (RBS). The surface morphology of silicon and silicide films before and after IBS has been imaged by atomic force microscopy (AFM), comprising conditions where typical nanodot or ripple patterns emerge on the former. In the case of irradiated Mo x Si1‑x surfaces, AFM shows a marked surface smoothing at normal incidence with and without additional Mo incorporation (the former results in nanodot patterns on Si). The morphological analysis also provides no evidence of ion-induced phase separation in irradiated Mo x Si1‑x . Contrary to silicon, Mo x Si1‑x surfaces also do not display ripple formation for (impurity free) oblique irradiations, except at grazing incidence conditions where parallel ripples emerge in a more evident fashion than in the Si counterpart. By means of RBS, irradiated Mo x Si1‑x films with 1 keV Ar+ at normal incidence have also been used to measure experimentally the (absolute) sputtering yield and rate of Si and Mo x Si1‑x materials. The analysis reveals that, under the present working conditions, the erosion rate of silicides is larger than for silicon, supporting simulations from the TRIDYN code. This finding questions the shielding effect from silicide regions as roughening mechanism in metal-assisted nanopatterning of silicon. On the contrary, the results highlight the relevance of in situ silicide formation. Ripple formation on Mo x Si1‑x under grazing incidence is also attributed to the dominance of sputtering effects under this geometry. In conclusion, our work provides some insights into the complex morphological evolution of compound surfaces and solid experimental evidences regarding the mechanisms behind silicide-assisted nanopatterning.

Effect of heavy oil on the development of the nervous system of floating and sinking teleost eggs.

PubMed

Irie, Kouta; Kawaguchi, Masahumi; Mizuno, Kaori; Song, Jun-Young; Nakayama, Kei; Kitamura, Shin-Ichi; Murakami, Yasunori

2011-01-01

Heavy oil (HO) on the sea surface penetrates into fish eggs and prevents the normal morphogenesis. To identify the toxicological effects of HO in the context of the egg types, we performed exposure experiments using floating eggs and sinking eggs. In the course of development, HO-exposed embryos of floating eggs showed abnormal morphology, whereas early larva of the sinking eggs had almost normal morphology. However, the developing peripheral nervous system of sinking eggs showed abnormal projections. These findings suggest that HO exposed fishes have problems in the developing neurons, although they have no morphological malformations. Through these observations, we conclude that HO is strongly toxic to floating eggs in the morphogenesis, and also affect the neuron development in both floating and sinking eggs. Copyright © 2011 Elsevier Ltd. All rights reserved.

RNA nanopatterning on graphene

NASA Astrophysics Data System (ADS)

Li, Q.; Froning, J. P.; Pykal, M.; Zhang, S.; Wang, Z.; Vondrák, M.; Banáš, P.; Čépe, K.; Jurečka, P.; Šponer, J.; Zbořil, R.; Dong, M.; Otyepka, M.

2018-07-01

Graphene-based materials enable the sensing of diverse biomolecules using experimental approaches based on electrochemistry, spectroscopy, or other methods. Although basic sensing was achieved, it had until now not been possible to understand and control biomolecules’ structural and morphological organization on graphene surfaces (i.e. their stacking, folding/unfolding, self-assembly, and nano-patterning). Here we present the insight into structural and morphological organization of biomolecules on graphene in water, using an RNA hairpin as a model system. We show that the key parameters governing the RNA’s behavior on the graphene surface are the number of graphene layers, RNA concentration, and temperature. At high concentrations, the RNA forms a film on the graphene surface with entrapped nanobubbles. The density and the size of the bubbles depend on the number of graphene layers. At lower concentrations, unfolded RNA stacks on the graphene and forms molecular clusters on the surface. Such a control over the conformational behavior of interacting biomolecules at graphene/water interfaces would facilitate new applications of graphene derivatives in biotechnology and biomedicine.

Growth of strained Si/relaxed SiGe heterostructures on Si(110) substrates using solid-source molecular beam epitaxy

NASA Astrophysics Data System (ADS)

Arimoto, Keisuke; Nakazawa, Hiroki; Mitsui, Shohei; Utsuyama, Naoto; Yamanaka, Junji; Hara, Kosuke O.; Usami, Noritaka; Nakagawa, Kiyokazu

2017-11-01

A strained Si/relaxed SiGe heterostructure grown on Si(110) substrate is attractive as a platform for high-hole-mobility Si-based electronic devices. To improve the electrical property, a smoother surface is desirable. In this study, we investigated surface morphology and microstructural aspects of strained Si/relaxed SiGe/Si(110) heterostructures grown by solid-source (SS) molecular beam epitaxy (MBE). It was revealed that SSMBE provides a way to grow strained Si/relaxed SiGe heterostructures with smooth surfaces. In addition, it was found that the strain in the SiGe layer of the SSMBE-grown sample is highly anisotropic whereas that of the GSMBE-grown sample is almost biaxially relaxed. Along with the surface morphology, the symmetry in degree of strain relaxation has implications for the electrical property. Results of a calculation shows that anisotropic strain is preferable for device application since it confines holes solely in the strained Si layer where hole mobility is enhanced.

Morphology and the Strength of Intermolecular Contact in Protein Crystals

NASA Technical Reports Server (NTRS)

Matsuura, Yoshiki; Chernov, Alexander A.

2002-01-01

The strengths of intermolecular contacts (macrobonds) in four lysozyme crystals were estimated based on the strengths of individual intermolecular interatomic interaction pairs. The periodic bond chain of these macrobonds accounts for the morphology of protein crystals as shown previously. Further in this paper, the surface area of contact, polar coordinate representation of contact site, Coulombic contribution on the macrobond strength, and the surface energy of the crystal have been evaluated. Comparing location of intermolecular contacts in different polymorphic crystal modifications, we show that these contacts can form a wide variety of patches on the molecular surface. The patches are located practically everywhere on this surface except for the concave active site. The contacts frequently include water molecules, with specific intermolecular hydrogen-bonds on the background of non-specific attractive interactions. The strengths of macrobonds are also compared to those of other protein complex systems. Making use of the contact strengths and taking into account bond hydration we also estimated crystal-water interfacial energies for different crystal faces.

Nanoscale morphological and chemical changes of high voltage lithium-manganese rich NMC composite cathodes with cycling.

PubMed

Yang, Feifei; Liu, Yijin; Martha, Surendra K; Wu, Ziyu; Andrews, Joy C; Ice, Gene E; Pianetta, Piero; Nanda, Jagjit

2014-08-13

Understanding the evolution of chemical composition and morphology of battery materials during electrochemical cycling is fundamental to extending battery cycle life and ensuring safety. This is particularly true for the much debated high energy density (high voltage) lithium-manganese rich cathode material of composition Li(1 + x)M(1 - x)O2 (M = Mn, Co, Ni). In this study we combine full-field transmission X-ray microscopy (TXM) with X-ray absorption near edge structure (XANES) to spatially resolve changes in chemical phase, oxidation state, and morphology within a high voltage cathode having nominal composition Li1.2Mn0.525Ni0.175Co0.1O2. Nanoscale microscopy with chemical/elemental sensitivity provides direct quantitative visualization of the cathode, and insights into failure. Single-pixel (∼ 30 nm) TXM XANES revealed changes in Mn chemistry with cycling, possibly to a spinel conformation and likely including some Mn(II), starting at the particle surface and proceeding inward. Morphological analysis of the particles revealed, with high resolution and statistical sampling, that the majority of particles adopted nonspherical shapes after 200 cycles. Multiple-energy tomography showed a more homogeneous association of transition metals in the pristine particle, which segregate significantly with cycling. Depletion of transition metals at the cathode surface occurs after just one cycle, likely driven by electrochemical reactions at the surface.

Nanoscale Morphological and Chemical Changes of High Voltage Lithium–Manganese Rich NMC Composite Cathodes with Cycling

PubMed Central

2015-01-01

Understanding the evolution of chemical composition and morphology of battery materials during electrochemical cycling is fundamental to extending battery cycle life and ensuring safety. This is particularly true for the much debated high energy density (high voltage) lithium–manganese rich cathode material of composition Li1 + xM1 – xO2 (M = Mn, Co, Ni). In this study we combine full-field transmission X-ray microscopy (TXM) with X-ray absorption near edge structure (XANES) to spatially resolve changes in chemical phase, oxidation state, and morphology within a high voltage cathode having nominal composition Li1.2Mn0.525Ni0.175Co0.1O2. Nanoscale microscopy with chemical/elemental sensitivity provides direct quantitative visualization of the cathode, and insights into failure. Single-pixel (∼30 nm) TXM XANES revealed changes in Mn chemistry with cycling, possibly to a spinel conformation and likely including some Mn(II), starting at the particle surface and proceeding inward. Morphological analysis of the particles revealed, with high resolution and statistical sampling, that the majority of particles adopted nonspherical shapes after 200 cycles. Multiple-energy tomography showed a more homogeneous association of transition metals in the pristine particle, which segregate significantly with cycling. Depletion of transition metals at the cathode surface occurs after just one cycle, likely driven by electrochemical reactions at the surface. PMID:25054780

Hexagonally ordered nanodots: Result of substrate rotation during oblique incidence low energy IBS

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

Chowdhury, Debasree, E-mail: debasree.chowdhury@saha.ac.in; Ghose, Debabrata, E-mail: debasree.chowdhury@saha.ac.in

The anisotropic regular patterns are often results during oblique incidence ion beam sputtering (IBS). Simultaneous substrate rotation (SR) during IBS can suppress surface roughening and removes anisotropic nature of surface pattern. Here, the evolution of Si surface morphology as result of with and without SR is studied during oblique incidence low energy Ar{sup +} sputtering. Resultant topography shows smooth surface to hexagonally ordered nanodots at different rotating conditions. Interestingly, surface roughness exhibits non-monotonic dependence on rotation frequency. The underlying mechanism for dot formation can be described within the framework of isotropic DKS equation.

Enhancing the biocompatibility of the polyurethane methacrylate and off-stoichiometry thiol-ene polymers by argon and nitrogen plasma treatment.

PubMed

Chen, Tiam Foo; Siow, Kim Shyong; Ng, Pei Yuen; Majlis, Burhanuddin Yeop

2017-10-01

Our studies focused on improving the biocompatibility properties of two microfluidic prototyping substrates i.e. polyurethane methacrylate (PUMA) and off-stoichiometry thiol-ene (OSTE-80) polymer by Ar and N 2 plasma treatment. The contact angle (CA) measurement showed that both plasma treatments inserted oxygen and nitrogen moieties increased the surface energy and hydrophilicity of PUMA and OSTE-80 polymer which corresponded to an increase of nitrogen to carbon ratios (N/C), as measured by XPS, to provide a conducive environment for cell attachments and proliferation. Under the SEM observation, the surface topography of PUMA and OSTE-80 polymer showed minimal changes after the plasma treatments. Furthermore, ageing studies showed that plasma-treated PUMA and OSTE-80 polymer had stable hydrophilicity and nitrogen composition during storage in ambient air for 15days. After in vitro cell culture of human umbilical vein endothelial cells (HUVECs) on these surfaces for 24h and 72h, both trypan blue and alamar blue assays indicated that PUMA and OSTE-80 polymer treated with N 2 plasma had the highest viability and proliferation. The polar nitrogen moieties, specifically amide groups, encouraged the HUVECs adhesion on the plasma-treated PUMA and OSTE-80 surfaces. Interestingly, PUMA polymer treated with Ar and N 2 plasma showed different HUVECs morphology which was spindle and cobblestone-shaped respectively after 72h of incubation. On the contrary, a monolayer of well-spread HUVECs formed on the Ar and N 2 plasma-treated OSTE-80 polymers. These variable morphologies observed can be ascribed to the adherence HUVECs on the different elastic moduli of these surfaces whereby further investigation might be needed. Overall, Ar and N 2 plasma treatment had successfully altered the surface properties of PUMA and OSTE-80 polymer by increasing its surface energy, hydrophilicity and chemical functionalities to create a biocompatible surface for HUVECs adhesion and proliferation. Copyright © 2017 Elsevier B.V. All rights reserved.

Solvothermal synthesis of hierarchical TiO2 nanostructures with tunable morphology and enhanced photocatalytic activity

NASA Astrophysics Data System (ADS)

Fan, Zhenghua; Meng, Fanming; Zhang, Miao; Wu, Zhenyu; Sun, Zhaoqi; Li, Aixia

2016-01-01

This paper presents controllable growth and photocatalytic activity of TiO2 hierarchical nanostructures by solvothermal method at different temperatures. It is revealed by scanning electron microscopy (SEM) and transmission electron microscopy (TEM) that the morphology of TiO2 can be effectively controlled as rose-like, chrysanthemum-like and sea-urchin-like only changing solvothermal temperature. BET surface area analysis confirms the presence of a mesoporous network in all the nanostructures, and shows high surface area at relatively high temperature. The photocatalytic activities of the photocatalysts are evaluated by the photodegradation of RhB under UV light irradiation. The TiO2 samples exhibit high activity on the photodegradation of RhB, which is higher than that of the commercial P25. The enhancement in photocatalytic performance can be attributed to the synergetic effect of the surface area, crystallinity, band gap and crystalline size.

Effect of Morphology and Manganese Valence on the Voltage Fade and Capacity Retention of Li[Li 2/12Ni 3/12Mn 7/12]O 2

DOE PAGES

Verde, Michael G.; Liu, Haodong; Carroll, Kyler J.; ...

2014-10-02

We have determined the electrochemical characteristics of the high voltage, high capacity Li-ion battery cathode material Li[Li 2/12Ni 3/12Mn 7/12]O 2 prepared using three different synthesis routes: sol-gel, hydroxide co-precipitation, and carbonate co-precipitation. Each route leads to distinct morphologies and surface areas while maintaining the same crystal structures. X-ray photoelectron spectroscopy (XPS) measurements reveal differences in their surface chemistries upon cycling, which correlate with voltage fading. As expected, we observed the valence state of Mn on the surface to decrease upon lithiation, and this reduction is specifically correlated to discharging below 3.6V. Furthermore, the data shows a correlation of themore » formation of Li 2CO 3 with Mn oxidation state from the« less

Microstructure of Sinter Deposit Formed at Hot Springs in West Sumatera

NASA Astrophysics Data System (ADS)

Putra, A.; Inanda, D. Y.; Buspa, F.; Salim, A. F.

2018-03-01

Sinter deposit emerged and spread at several hot springs in West Sumatera is divided into three types, they are full silica, half silica-carbonate and full carbonate. This work intends to investigate the characteristic of each type by its crystalline structure and morphology and its correlation to surface temperature. The research is focused on Sapan Maluluang hot spring (full silica), Garara hot spring (half silica-carbonate) and Bawah Kubang hot spring (full carbonate). Crystalline structure is analyzed by X-Ray Diffraction (XRD) methods, it showed that deposit from Sapan Maluluang has opal-A structure, Garara has opal-CT structure and Bawah Kubang has crystalline structure. The Scanning Electron Microscopy (SEM) methods is applied to describe its morphology surface, in which spherical, almost rounded and irregular textured was formed at each deposit, respectively. Surface temperature of hot spring also has given impact on deposit texture.

Endocytosis and interaction of poly (amidoamine) dendrimers with Caco-2 cells.

PubMed

Kitchens, Kelly M; Foraker, Amy B; Kolhatkar, Rohit B; Swaan, Peter W; Ghandehari, Hamidreza

2007-11-01

To investigate the internalization and subcellular trafficking of fluorescently labeled poly (amidoamine) (PAMAM) dendrimers in intestinal cell monolayers. PAMAM dendrimers with positive or negative surface charge were conjugated to fluorescein isothiocyanate (FITC) and visualized for colocalization with endocytosis markers using confocal microscopy. Effect of concentration, generation and charge on the morphology of microvilli was observed using transmission electron microscopy. Both cationic and anionic PAMAM dendrimers internalized within 20 min, and differentially colocalized with endocytosis markers clathrin, EEA-1, and LAMP-1. Transmission electron microscopy analysis showed a concentration-, generation- and surface charge-dependent effect on microvilli morphology. These studies provide visual evidence that endocytic mechanism(s) contribute to the internalization and subcellular trafficking of PAMAM dendrimers across the intestinal cells, and that appropriate selection of PAMAM dendrimers based on surface charge, concentration and generation number allows the application of these polymers for oral drug delivery.

Effect of nitric acid treatment on activated carbon derived from oil palm shell

NASA Astrophysics Data System (ADS)

Allwar, Allwar; Hartati, Retno; Fatimah, Is

2017-03-01

The primary object of this work is to study the effect of nitric acid on the porous and morphology structure of activated carbon. Production of activated carbon from oil palm shell was prepared with pyrolysis process at temperature 900°C and by introduction of 10 M nitric acid. Determination of surface area, pore volume and pore size distribution of activated carbon was conducted by the N2 adsorption-desorption isotherm at 77 K. Morphology structure and elemental micro-analysis of activated carbon were estimated by Scanning Electron Microscopy (SEM) and energy dispersive X-ray (EDX), respectively. The result shows that activated carbon after treating with nitric acid proved an increasing porous characteristics involving surface area, pore volume and pore size distribution. It also could remove the contaminants including metals and exhibit an increasing of pores and crevices all over the surface.

Magnetic field controlled graphene oxide-based origami with enhanced surface area and mechanical properties.

PubMed

Park, Ok-Kyung; Tiwary, Chandra Sekhar; Yang, Yang; Bhowmick, Sanjit; Vinod, Soumya; Zhang, Qingbo; Colvin, Vicki L; Asif, S A Syed; Vajtai, Robert; Penev, Evgeni S; Yakobson, Boris I; Ajayan, Pulickel M

2017-06-01

One can utilize the folding of paper to build fascinating 3D origami architectures with extraordinary mechanical properties and surface area. Inspired by the same, the morphology of 2D graphene can be tuned by addition of magnetite (Fe 3 O 4 ) nanoparticles in the presence of a magnetic field. The innovative 3D architecture with enhanced mechanical properties also shows a high surface area (∼2500 m 2 g -1 ) which is utilized for oil absorption. Detailed microscopy and spectroscopy reveal rolling of graphene oxide (GO) sheets due to the magnetic field driven action of magnetite particles, which is further supported by molecular dynamics (MD) simulations. The macroscopic and local deformation resulting from in situ mechanical loading inside a scanning electron microscope reveals a change in the mechanical response due to a change internal morphology, which is further supported by MD simulation.

Corn stalks char from fast pyrolysis as precursor material for preparation of activated carbon in fluidized bed reactor.

PubMed

Wang, Zhiqi; Wu, Jingli; He, Tao; Wu, Jinhu

2014-09-01

Corn stalks char from fast pyrolysis was activated by physical and chemical activation process in a fluidized bed reactor. The structure and morphology of the carbons were characterized by N2 adsorption and SEM. Effects of activation time and activation agents on the structure of activation carbon were investigated. The physically activated carbons with CO2 have BET specific surface area up to 880 m(2)/g, and exhibit microporous structure. The chemically activated carbons with H3PO4 have BET specific surface area up to 600 m(2)/g, and exhibit mesoporous structure. The surface morphology shows that physically activated carbons exhibit fibrous like structure in nature with long ridges, resembling parallel lines. Whereas chemically activated carbons have cross-interconnected smooth open pores without the fibrous like structure. Copyright © 2014 Elsevier Ltd. All rights reserved.

Influence of bases on hydrothermal synthesis of titanate nanostructures

NASA Astrophysics Data System (ADS)

Sikhwivhilu, Lucky M.; Sinha Ray, Suprakas; Coville, Neil J.

2009-03-01

A hydrothermal treatment of titanium dioxide (TiO2) with various bases (i.e., LiOH, NaOH, KOH, and NH4OH) was used to prepare materials with unique morphologies, relatively small crystallite sizes, and large specific surface areas. The experimental results show that the formation of TiO2 is largely dependent on the type, strength and concentration of a base. The effect of the nature of the base used and the concentration of the base on the formation of nanostructures were investigated using X-ray diffraction, Raman spectroscopy, transmission and scanning electron microscopy, as well as surface area measurements. Sodium hydroxide (NaOH) and potassium hydroxide (KOH) were both used to transform the morphology of starting TiO2 material.

Transport (electrical and thermal) properties and surface morphology of Y1-xCaxFeO3 (where x = 0.03 and 0.05) ceramics

NASA Astrophysics Data System (ADS)

Suthar, Lokesh; Bhadala, Falguni; Roy, M.; Jha, V. K.

2018-05-01

The electrical transport behaviour of polycrystalline Calcium doped Yttrium orthoferrite (Y1-xCaxFeO3, where x = 0.03 and 0.05) have been synthesized by high temperature Solid state reaction route. The I-V characteristics have been measured which revels that Y1-xCaxFeO3 (where x = 0.03 and 0.05), behaves like semiconductor and its conductivity increases with increase in doping concentration. The thermal analysis experiment shows no phase change with the minor weight loss which reflects the high temperature thermal stability of the materials. The surface morphology was analyzed using the AFM. The results are discussed in detail.

Effects of different crystal faces on the surface charge of colloidal goethite (α-FeOOH) particles: an experimental and modeling study

NASA Astrophysics Data System (ADS)

Gaboriaud, Fabien; Ehrhardt, Jean-Jacques

2003-03-01

The surface charge of colloidal particles is usually determined by potentiometric titration. These acid-base titrations make it possible to measure the pH of point-of-zero charge (pzc) for oxide minerals. This macroscopic property is the most important parameter used in surface complexation modeling to reproduce experimental data. The pzc values of goethite reported in the literature vary between 7.0 and 9.5. Carbonate adsorption and/or surface morphology are thought to account for this wide range. We demonstrate a procedure for the removal of the carbonate ions that initially adsorb on goethite and strongly affect the titration curves and pzc determination. We also investigated the crystal-face-specific reactivity of two morphologically different goethites. The z-profiles obtained from atomic force microscopy (AFM) images showed that the goethite with the smallest specific surface area ( S = 49 m 2/g, denoted G49) exhibits 70% of the (001) face, whereas this value is only 30% for the goethite with largest specific surface area ( S = 95 m 2/g, denoted G95). This morphologic difference results in slightly different pzc values: 9.0 for G49 goethite and 9.1 for G95 geothite. These experimental pzc values have been correlated with multisite complexation calculations using both the full-site and the 1-pK approaches. We used the full-site approach to consider all of the configurations of hydrogen bond interactions with surface site. The resulting mean charges gave estimated pzc values of 8.9 and 9.2 for the (001) and (101) faces, respectively. Considering these theoretical pzc values for individual faces and the face distributions obtained from AFM analysis, the calculated pzc values are in full agreement with the experimental pzc values. However, this morphologic difference is more expressed in surface charge values than in the pzc values. Indeed, the surface charge of G49 goethite is much higher than that of G95 goethite, and the 1-pK calculations make it possible to fit the titration data satisfactorily.

Simultaneous tuning of chemical composition and topography of copolymer surfaces: micelles as building blocks.

PubMed

Zhao, Ning; Zhang, Xiaoyan; Zhang, Xiaoli; Xu, Jian

2007-05-14

A simple method is described for controlling the surface chemical composition and topography of the diblock copolymer poly(styrene)-b-poly(dimethylsiloxane)(PS-b-PDMS) by casting the copolymer solutions from solvents with different selectivities. The surface morphology and chemical composition were characterized by scanning electron microscopy (SEM) and X-ray photoelectron spectroscopy (XPS), respectively, and the wetting behavior was studied by water contact angle (CA) and sliding angle (SA) and by CA hysteresis. Chemical composition and morphology of the surface depend on solvent properties, humidity of the air, solution concentration, and block lengths. If the copolymer is cast from a common solvent, the resultant surface is hydrophobic, with a flat morphology, and dominated by PDMS on the air side. From a PDMS-selective solvent, the surface topography depends on the morphology of the micelles. Starlike micelles give rise to a featureless surface nearly completely covered by PDMS, while crew-cut-like micelles lead to a rough surface with a hierarchical structure that consists partly of PDMS. From a PS-selective solvent, however, surface segregation of PDMS was restricted, and the surface morphology can be controlled by vapor-induced phase separation. On the basis of the tunable surface roughness and PDMS concentration on the air side, water repellency of the copolymer surface could be tailored from hydrophobic to superhydrophobic. In addition, reversible switching behavior between hydrophobic and superhydrophobic can be achieved by exposing the surface to solvents with different selectivities.

2D scaling behavior of nanotextured GaN surfaces: A case study of hillocked and terraced surfaces

NASA Astrophysics Data System (ADS)

Mutta, Geeta Rani; Carapezzi, Stefania

2018-07-01

The 2D scaling properties of GaN surfaces have been studied by means of the 2D height-height correlation function (HHCF). The GaN layers under investigation presented exemplar morphologies, generated by distinct growth methods: a molecular beam epitaxy (MBE) grown surface decorated by hillocks and a metal organic vapor phase epitaxy (MOVPE) grown surface with terraced structure. The 2D statistical analysis of these surfaces has allowed assessing quantitatively the degree of morphological variability along all the different directions across each surface, their corresponding roughness exponents and correlation lengths. A scaling anisotropy as well as correlation length anisotropy has been detected for both hillocked and terraced surfaces. Especially, a marked dependence of correlation length from the direction across the terraced surface has been observed. Additionally, the terraced surfaces showed the lower root mean square (RMS) roughness value and at the same time, the lower roughness exponent value. This could appear as a contradiction, given that a low RMS value is associated to a smooth surface, and usually the roughness exponent is interpreted as a "measure" of the smoothness of the surface, the smoother the surface, the higher (approaching the unity) is the roughness exponent. Our case study is an experimental demonstration in which the roughness exponent should be, more appropriately, interpreted as a quantification of how the roughness changes with length scale.

Comparison study of biomimetic strontium-doped calcium phosphate coatings by electrochemical deposition and air plasma spray: morphology, composition and bioactive performance.

PubMed

Li, Ling; Lu, Xia; Meng, Yizhi; Weyant, Christopher M

2012-10-01

In this study, strontium-doped calcium phosphate coatings were deposited by electrochemical deposition and plasma spray under different process parameters to achieve various coating morphologies. The coating composition was investigated by energy dispersive X-ray spectroscopy and X-ray diffraction. The surface morphologies of the coatings were studied through scanning electron microscopy while the cytocompatibility and bioactivity of the strontium-doped calcium phosphate coatings were evaluated using bone cell culture using MC3T3-E1 osteoblast-like cells. The addition of strontium leads to enhanced proliferation suggesting the possible benefits of strontium incorporation in calcium phosphate coatings. The morphology and composition of deposited coatings showed a strong influence on the growth of cells.

Influence of Synthesis Temperature on the Growth and Surface Morphology of Co3O4 Nanocubes for Supercapacitor Applications

PubMed Central

Samal, Rashmirekha; Dash, Barsha; Sarangi, Chinmaya Kumar; Subbaiah, Tondepu; Senanayake, Gamini; Minakshi, Manickam

2017-01-01

A facile hydrothermal route to control the crystal growth on the synthesis of Co3O4 nanostructures with cube-like morphologies has been reported and tested its suitability for supercapacitor applications. The chemical composition and morphologies of the as-prepared Co3O4 nanoparticles were extensively characterized using X-ray diffraction (XRD) and transmission electron microscopy (TEM). Varying the temperature caused considerable changes in the morphology, the electrochemical performance increased with rising temperature, and the redox reactions become more reversible. The results showed that the Co3O4 synthesized at a higher temperature (180 °C) demonstrated a high specific capacitance of 833 F/g. This is attributed to the optimal temperature and the controlled growth of nanocubes. PMID:29088061

MC3T3-E1 Cells on Titanium Surfaces with Nanometer Smoothness and Fibronectin Immobilization

PubMed Central

Hayakawa, Tohru; Yoshida, Eiji; Yoshimura, Yoshitaka; Uo, Motohiro; Yoshinari, Masao

2012-01-01

The present study was aimed to evaluate the viability and total protein contents of osteoblast-like cells on the titanium surface with different surface mechanical treatment, namely, nanometer smoothing (Ra: approximately 2.0 nm) and sandblasting (Ra: approximately 1.0 μm), and biochemical treatment, namely, with or without fibronectin immobilization. Fibronectin could be easily immobilized by tresyl chloride-activation technique. MC3T3-E1 cells were seeded on the different titanium surfaces. Cell viability was determined by MTT assay. At 1 day of cell culture, there were no significant differences in cell viability among four different titanium surfaces. At 11 days, sandblasted titanium surface with fibronectin immobilization showed the significantly highest cell viability than other titanium surface. No significant differences existed for total protein contents among four different titanium surfaces at 11 days of cell culture. Scanning electron microscopy observation revealed that smoothness of titanium surface produced more spread cell morphologies, but that fibronectin immobilization did not cause any changes of the morphologies of attached cells. Fibronectin immobilization provided greater amount of the number of attached cells and better arrangement of attached cells. In conclusion, the combination of sandblasting and fibronectin immobilization enhanced the cell viability and fibronectin immobilization providing better arrangements of attached cells. PMID:22675359

Ultrathin Au film on polymer surface for surface plasmon polariton waveguide application

NASA Astrophysics Data System (ADS)

Liu, Tong; Ji, Lanting; He, Guobing; Sun, Xiaoqiang; Wang, Fei; Zhang, Daming

2017-11-01

Formation of laterally continuous ultrathin gold films on polymer substrates is a technological challenge. In this work, the vacuum thermal evaporation method is adopted to form continuous Au films in the thickness range of 7-17 nm on polymers of Poly(methyl-methacrylate-glycidly-methacrylate) and SU-8 film surface without using the adhesion or metallic seeding layers. Absorption spectrum, scanning electron microscope and atomic force microscope images are used to characterize the Au film thickness, roughness and optical loss. The result shows that molecular-scale structure, surface energy and electronegativity have impacts on the Au film morphology on polymers. Wet chemical etching is used to fabricate 7-nm thick Au stripes embedded in polymer claddings. These long-range surface plasmon polariton waveguides demonstrate the favorable morphological configurations and cross-sectional states. Through the end-fire excitation method, propagation losses of 6-μm wide Au stripes are compared to theoretical values and analyzed from practical film status. The smooth, patternable gold films on polymer provide potential applications to plasmonic waveguides, biosensing, metamaterials and optical antennas.

Adhering grains and surface features on two Itokawa particles

DOE PAGES

Dobrica, E.; Ogliore, R. C.

2016-02-13

We investigated the surface texture and chemical compositions of two ~40-μm particles returned from the surface regolith of asteroid Itokawa (RB-DQ04-0062 and RB-DQ04-0091) by the Japan Aerospace Exploration Agency’s Hayabusa mission. We identified splash melts, surface blistering, and many small adhering particles. Seven focused ion beam sections were extracted from both Itokawa particles, targeting one splash melt and ten adhering particles to investigate their composition and provenance and the role of micrometeoroid impacts on Itokawa’s surface. Based on the particle’s structure, mineralogy, and interface between the adhering particle and host grain, we identified lithic fragments and particles deposited by impact.more » These have morphologies and compositions consistent with impact-generated deposits: two have morphologies and compositions that are consistent with impact-generated silica glass, and one was a Ni-free, metallic Fe, and S-rich assemblage that was likely generated by vapor recondensation during a micrometeoroid impact. Here this study shows that, even though its regolith is young, micrometeoroid impacts have altered the regolith of asteroid Itokawa.« less

Shrink-induced graphene sensor for alpha-fetoprotein detection with low-cost self-assembly and label-free assay

NASA Astrophysics Data System (ADS)

Sando, Shota; Zhang, Bo; Cui, Tianhong

2017-12-01

Combination of shrink induced nano-composites technique and layer-by-layer (LbL) self-assembled graphene challenges controlling surface morphology. Adjusting shrink temperature achieves tunability on graphene surface morphology on shape memory polymers, and it promises to be an alternative in fields of high-surface-area conductors and molecular detection. In this study, self-assembled graphene on a shrink polymer substrate exhibits nanowrinkles after heating. Induced nanowrinkles on graphene with different shrink temperature shows distinct surface roughness and wettability. As a result, it becomes more hydrophilic with higher shrink temperatures. The tunable wettability promises to be utilized in, for example, microfluidic devices. The graphene on shrink polymer also exhibits capability of being used in sensing applications for pH and alpha-fetoprotein (AFP) detection with advantages of label free and low cost, due to self-assembly technique, easy functionalization, and antigen-antibody reaction on graphene surface. The detection limit of AFP detection is down to 1 pg/mL, and therefore the sensor also has a significant potential for biosensing as it relies on low-cost self-assembly and label-free assay.

AFM study of the morphologic change of HDPE surface photografted with glycidyl methacrylate.

PubMed

Wang, Huiliang; Han, Jianmei

2009-05-01

The UV-induced grafting of glycidyl methacrylate (GMA) onto high-density polyethylene (HDPE) and the atomic force microscopy (AFM) study of the morphologic change of the grafted surface are reported. The grafting was carried out in GMA acetone solutions with different monomer concentrations. Grafting was much faster in a solution with a higher monomer concentration. FTIR analyses proved that GMA had been successfully grafted onto HDPE. The morphologies of grafted HDPE surfaces changed with UV irradiation time. The monomer concentration had a significant effect on the morphologies of the grafted HDPE surfaces. The HDPE surface grafted in a solution with a higher monomer concentration was much rougher than that grafted in a solution with a lower monomer concentration. The growth models of the grafted granules or clusters are also proposed.

Morphology of sustentaculum tali: Biomechanical importance and correlation with angular dimensions of the talus.

PubMed

Mahato, Niladri Kumar

2011-12-01

The talus and the calcaneus share the bulk of load transmitted from the leg to the skeleton of the foot. The present study analyses the inter-relationship between the superior articular surface and the angular dimensions of the talus with the morphology of the sustentaculum tali. Identification of possible relationships between different angular parameters of the talus morphology and the sustentaculum tali in context of load transmission through the foot. One articular surface and three angular parameters at the junction of the head and the body were measured from dried human talar bones. Corresponding calcaneal samples were measured for four dimensions at the sustentaculum tali. Correlation and regression statistical values between parameters were worked out and analysed. Several parameters within the talus demonstrated significant correlations amongst themselves. The neck vertical angle showed a strong correlation with the articulating surface area below the head of the talus. The inter-relationship between articular and angular parameters within the talus demonstrates strong correlation for certain parameters. Data presented in the study may be helpful to adjust calcaneal and talar screw placement techniques, prosthesis designing and bio-mechanical studies at this important region. Copyright © 2011 Elsevier Ltd. All rights reserved.

Architecture-dependent surface chemistry for Pt monolayers on carbon-supported Au.

PubMed

Cheng, Shuang; Rettew, Robert E; Sauerbrey, Marc; Alamgir, Faisal M

2011-10-01

Pt monolayers were grown by surface-limited redox replacement (SLRR) on two types of Au nanostructures. The Au nanostructures were fabricated electrochemically on carbon fiber paper (CFP) by either potentiostatic deposition (PSD) or potential square wave deposition (PSWD). The morphology of the Au/CFP heterostructures, examined using scanning electron microscopy (SEM), was found to depend on the type of Au growth method employed. The properties of the Pt deposit, as studied using X-ray photoelectron spectroscopy (XPS), X-ray absorption spectroscopy (XAS), and cyclic voltammetry (CV), were found to depend strongly on the morphology of the support. Specifically, it was found that smaller Au morphologies led to a higher degree of cationicity in the resulting Pt deposit, with Pt(4+) and Pt(2+) species being identified using XPS and XAS. For fuel-cell catalysts, the resistance of ultrathin catalyst deposits to surface area loss through dissolution, poisoning, and agglomeration is critical. This study shows that an equivalent of two monolayers (ML) is the low-loading limit of Pt on Au. At 1 ML or below, the Pt film decreases in activity and durability very rapidly due to presence of cationic Pt. © 2011 American Chemical Society

Morphology and defect structure of the CeO 2(1 1 1) films grown on Ru(0 0 0 1) as studied by scanning tunneling microscopy

NASA Astrophysics Data System (ADS)

Lu, J.-L.; Gao, H.-J.; Shaikhutdinov, S.; Freund, H.-J.

2006-11-01

The morphology of ceria films grown on a Ru(0 0 0 1) substrate was studied by scanning tunneling microscopy in combination with low-energy electron diffraction and Auger electron spectroscopy. The preparation conditions were determined for the growth of nm-thick, well-ordered CeO 2(1 1 1) films covering the entire surface. The recipe has been adopted from the one suggested by Mullins et al. [D.R. Mullins, P.V. Radulovic, S.H. Overbury, Surf. Sci. 429 (1999) 186] and modified in that significantly higher oxidation temperatures are required to form atomically flat terraces, up to 500 Å in width, with a low density of the point defects assigned to oxygen vacancies. The terraces often consist of several rotational domains. A circular shape of terraces suggest a large variety of undercoordinated sites at the step edges which preferentially nucleate gold particles deposited onto these films. The results show that reactivity studies over ceria and metal/ceria surfaces should be complemented with STM studies, which provide direct information on the film morphology and surface defects, which are usually considered as active sites for catalysis over ceria.

Revealing Surface States in In-Doped SnTe Nanoplates with Low Bulk Mobility.

PubMed

Shen, Jie; Xie, Yujun; Cha, Judy J

2015-06-10

Indium (In) doping in topological crystalline insulator SnTe induces superconductivity, making In-doped SnTe a candidate for a topological superconductor. SnTe nanostructures offer well-defined nanoscale morphology and high surface-to-volume ratios to enhance surface effects. Here, we study In-doped SnTe nanoplates, In(x)Sn(1-x)Te, with x ranging from 0 to 0.1 and show they superconduct. More importantly, we show that In doping reduces the bulk mobility of In(x)Sn(1-x)Te such that the surface states are revealed in magnetotransport despite the high bulk carrier density. This is manifested by two-dimensional linear magnetoresistance in high magnetic fields, which is independent of temperature up to 10 K. Aging experiments show that the linear magnetoresistance is sensitive to ambient conditions, further confirming its surface origin. We also show that the weak antilocalization observed in In(x)Sn(1-x)Te nanoplates is a bulk effect. Thus, we show that nanostructures and reducing the bulk mobility are effective strategies to reveal the surface states and test for topological superconductors.

Expanding Cancer Detection Using Molecular Imprinting for a Novel Point-of-Care Diagnostic Device

NASA Astrophysics Data System (ADS)

Yu, Yingjie; Rafailovich, Miriam; Wang, Yantian; Ranjbaran, Alina; Wang, Tom; Nam, David

2012-02-01

We propose the use of a potentiometric biosensor that incorporates the efficient and specific molecular imprinting (MI) method with a self-assembled monolayer (SAM). We first tested the biosensor using carcinoembryonic antigen, CEA, a biomarker associated with pancreatic cancer. No change in detection efficiency was observed when detection was performed in the presence of 100% serum albumin, indicating that the sensor is able to discriminate for the template analyte even in concentrated solution of similar substances. Computer simulations of the protein structure were performed in order to estimate the changes in morphology and determine the sensitivity of the biosensor to conformational changes in the proteins. We found that even small changes in PH can generate rotation of the surface functional groups, without significant change in the morphology. Yet, the results show that only when the detection and imprinting conditions are similar, robust signals occurs. Hence we concluded that both morphology and surface chemistry play a role in the recognition.

Nanomanufacturing of titania interfaces with controlled structural and functional properties by supersonic cluster beam deposition

NASA Astrophysics Data System (ADS)

Podestà, Alessandro; Borghi, Francesca; Indrieri, Marco; Bovio, Simone; Piazzoni, Claudio; Milani, Paolo

2015-12-01

Great emphasis is placed on the development of integrated approaches for the synthesis and the characterization of ad hoc nanostructured platforms, to be used as templates with controlled morphology and chemical properties for the investigation of specific phenomena of great relevance in interdisciplinary fields such as biotechnology, medicine, and advanced materials. Here, we discuss the crucial role and the advantages of thin film deposition strategies based on cluster-assembling from supersonic cluster beams. We select cluster-assembled nanostructured titania (ns-TiO2) as a case study to demonstrate that accurate control over morphological parameters can be routinely achieved, and consequently, over several relevant interfacial properties and phenomena, like surface charging in a liquid electrolyte, and proteins and nanoparticles adsorption. In particular, we show that the very good control of nanoscale morphology is obtained by taking advantage of simple scaling laws governing the ballistic deposition regime of low-energy, mass-dispersed clusters with reduced surface mobility.

Nanomanufacturing of titania interfaces with controlled structural and functional properties by supersonic cluster beam deposition

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

Podestà, Alessandro, E-mail: alessandro.podesta@mi.infn.it, E-mail: pmilani@mi.infn.it; Borghi, Francesca; Indrieri, Marco

Great emphasis is placed on the development of integrated approaches for the synthesis and the characterization of ad hoc nanostructured platforms, to be used as templates with controlled morphology and chemical properties for the investigation of specific phenomena of great relevance in interdisciplinary fields such as biotechnology, medicine, and advanced materials. Here, we discuss the crucial role and the advantages of thin film deposition strategies based on cluster-assembling from supersonic cluster beams. We select cluster-assembled nanostructured titania (ns-TiO{sub 2}) as a case study to demonstrate that accurate control over morphological parameters can be routinely achieved, and consequently, over several relevantmore » interfacial properties and phenomena, like surface charging in a liquid electrolyte, and proteins and nanoparticles adsorption. In particular, we show that the very good control of nanoscale morphology is obtained by taking advantage of simple scaling laws governing the ballistic deposition regime of low-energy, mass-dispersed clusters with reduced surface mobility.« less

Evolution of Morphology and Crystallinity of Silica Minerals Under Hydrothermal Conditions

NASA Astrophysics Data System (ADS)

Isobe, H.

2011-12-01

Silica minerals are quite common mineral species in surface environment of the terrestrial planets. They are good indicator of terrestrial processes including hydrothermal alteration, diagenesis and soil formation. Hydrothermal quartz, metastable low temperature cristobalite and amorphous silica show characteristic morphology and crystallinity depending on their formation processes and kinetics under wide range of temperature, pressure, acidity and thermal history. In this study, silica minerals produced by acidic hydrothermal alteration related to volcanic activities and hydrothermal crystallization experiments from diatom sediment are examined with crystallographic analysis and morphologic observations. Low temperature form of cistobalite is a metastable phase and a common alteration product occured in highly acidic hydrothermal environment around fumaroles in geothermal / volcanic areas. XRD analysis revealed that the alteration degree of whole rock is represented by abundance of cristobalite. Detailed powder XRD analysis show that the primary diffraction peak of cristobalite composed with two or three phases with different d-spacing and FWHM by peak profile fitting analysis. Shorter d-spacing and narrower FWHM cristobalite crystallize from precursor materials with less-crystallized, longer d-spacing and wider FWHM cristobalite. Textures of hydrothermal cristobalite in altered rock shows remnant of porphylitic texture of the host rock, pyroxene-amphibole andesite. Diatom has amorphous silica shell and makes diatomite sediment. Diatomite found in less diagenetic Quarternary formation keeps amorphous silica diatom shells. Hydrothermal alteration experiments of amorphous silica diatomite sediment are carried out from 300 °C to 550 °C. Mineral composition of run products shows crystallization of cristobalite and quartz progress depending on temperature and run durations. Initial crystallization product, cristobalite grains occur as characteristic lepispheres and granules with various surface structures. At the very initial stage of cristobalite crystallization within 2 days run duration, cristobalite shows lepispheres a few micron meters in diameter with irregular, submicron scale ridges and grooves on the surface. With the run duration up to 7 days, lepispheres change to granules with smooth surface remaining a few micron meters in diameter. Crystallinity of cristobalite lepispheres and granules corresponds to opal-CT. Euhedral quartz crystals grow with dissolution of cristobalite grains. Growth rate of cristobalite and quartz is controlled by crystallization kinetics with induction period strongly depending on temperature. Induction period of cristobalite crystallization from amorphous silica may exceed several million years at temperature below 100 °C. Crystallinity, morphology and growth rate of silica minerals occurred in various terrestrial and planetary processes are controlled by temperature and acidity of hydrothermal fluid and nucleation and growth kinetics of silica minerals.

Morphology and mechanism of the very large dunes in the tidal reach of the Yangtze River, China

NASA Astrophysics Data System (ADS)

Shuwei, Zheng; Heqin, Cheng; Shuaihu, Wu; Shengyu, Shi; Wei, Xu; Quanping, Zhou; Yuehua, Jiang

2017-05-01

High-resolution multibeam data was used to interpret the surface morphology of very large dunes (VLDs) in the tidal reach of the Yangtze River, China. These VLDs can be divided into three categories according to their surface morphological characteristics. (1) VLDs-I: those with a smooth surface and cross-section; (2) VLDs-II: those accompanied by secondary dunes; (3) VLDs-III: those accompanied by secondary dunes and numerous elliptical pits. Parameters and spatial distribution of VLDs, and bed surface sediment were analyzed in the laboratory. Overall, channel morphology is an important factor affecting the development of VLDs, and channels with narrow and straight and certain water surface slope are facilitating the development of VLDs by constraining stream power. Meanwhile, distribution density of VLDs depicts a decreasing trend from Chizhou towards the estuary, are probably influenced by channel morphology and width. Associated pits in VLDs-III change the 3D dune morphology by distributing in secondary dunes as beads. The Three Gorges Dam project (TGP) leads to the bed surface sediment activity frequently and leads to the riverbed surface sediment coarsens, which promotes the further development of dunes. Moreover, other human activities, such as river regulation project, sand mining and Deep Water Channel Regulation Project have changed the regional river boundary conditions and hydrodynamic conditions are influential on the development of VLDs.

The Effect of Cutting Speed in Metallic Glass Grinding

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

Serbest, Erdinc; Bakkal, Mustafa; Karipcin, Ilker

2011-01-17

In this paper, the effects of the cutting speed in metallic glass grinding were investigated in dry conditions. The results showed that grinding forces decrease as grinding energy increase with the increasing cutting speeds. The present investigations on ground surface and grinding chips morphologies -shows that material removal and surface formation of the BMG are mainly due to the ductile chip deformation and ploughing as well as brittle fracture of some particles from the edges of the tracks. The roughness values obtained with the Cubic Boron Nitride wheels are acceptable for the grinding operation.

Preparation and cupric ion release behavior of Cu/LDPE porous composites with tunable pore morphology for intrauterine devices.

PubMed

Xiao, Lian; Xia, Xianping; Xie, Changsheng; Ge, Man; Xiao, Cheng; Cai, Shuizhou

2013-07-01

Copper/low-density polyethylene (Cu/LDPE) porous composites are novel materials for copper-containing intrauterine devices (Cu-IUDs). Here we report a method, i.e., by changing the mass ratio of two kinds of porogens that have different melting points through the combined techniques of injection molding and particulate leaching, to prepare the Cu/LDPE porous composites with tunable pore morphology. After these Cu/LDPE porous composites with different pore morphologies were obtained, the influences of pore morphologies on their cupric ion release behaviors were studied. The results show that the pore morphology has great influence on the cupric ion release behavior of Cu/LDPE porous composites. This phenomenon is caused by the different influences of different pore morphologies on the effective porosity and the surface hydrophilicity. And those results can be applied to guide the fabrication of Cu/LDPE porous composite Cu-IUDs with minimal weight at an appropriate cupric ion release rate. Copyright © 2013 Elsevier B.V. All rights reserved.

Surface-functionalized cockle shell–based calcium carbonate aragonite polymorph as a drug nanocarrier

PubMed Central

Mohd Abd Ghafar, Syairah Liyana; Hussein, Mohd Zobir; Rukayadi, Yaya; Abu Bakar Zakaria, Md Zuki

2017-01-01

Calcium carbonate aragonite polymorph nanoparticles derived from cockle shells were prepared using surface functionalization method followed by purification steps. Size, morphology, and surface properties of the nanoparticles were characterized using transmission electron microscopy, field emission scanning electron microscopy, dynamic light scattering, zetasizer, X-ray powder diffraction, and Fourier transform infrared spectrometry techniques. The potential of surface-functionalized calcium carbonate aragonite polymorph nanoparticle as a drug-delivery agent were assessed through in vitro drug-loading test and drug-release test. Transmission electron microscopy, field emission scanning electron microscopy, and particle size distribution analyses revealed that size, morphology, and surface characterization had been improved after surface functionalization process. Zeta potential of the nanoparticles was found to be increased, thereby demonstrating better dispersion among the nanoparticles. Purification techniques showed a further improvement in the overall distribution of nanoparticles toward more refined size ranges <100 nm, which specifically favored drug-delivery applications. The purity of the aragonite phase and their chemical analyses were verified by X-ray powder diffraction and Fourier transform infrared spectrometry studies. In vitro biological response of hFOB 1.19 osteoblast cells showed that surface functionalization could improve the cytotoxicity of cockle shell–based calcium carbonate aragonite nanocarrier. The sample was also sensitive to pH changes and demonstrated good abilities to load and sustain in vitro drug. This study thus indicates that calcium carbonate aragonite polymorph nanoparticles derived from cockle shells, a natural biomaterial, with modified surface characteristics are promising and can be applied as efficient carriers for drug delivery. PMID:28572724

Hydration kinetics and morphology of cement pastes with pozzolanic volcanic ash studied via synchrotron-based techniques

DOE PAGES

Kupwade-Patil, Kunal; Chin, Stephanie; Ilavsky, Jan; ...

2017-10-13

Here, this study investigates the early ages of hydration behavior when basaltic volcanic ash was used as a partial substitute to ordinary Portland cement using ultra-small-angle X-ray scattering and wide-angle X-ray scattering (WAXS). The mix design consisted of 10, 30 and 50% substitution of Portland cement with two different-sized volcanic ashes. The data showed that substitution of volcanic ash above 30% results in excess unreacted volcanic ash, rather than additional pozzolanic reactions along longer length scales. WAXS studies revealed that addition of finely ground volcanic ash facilitated calcium-silicate-hydrate related phases, whereas inclusion of coarser volcanic ash caused domination by calcium-aluminum-silicate-hydratemore » and unreacted MgO phases, suggesting some volcanic ash remained unreacted throughout the hydration process. Addition of more than 30% volcanic ash leads to coarser morphology along with decreased surface area and higher intensity of scattering at early-age hydration. This suggests an abrupt dissolution indicated by changes in surface area due to the retarding gel formation that can have implication on early-age setting influencing the mechanical properties of the resulting cementitious matrix. The findings from this work show that the concentration of volcanic ash influences the specific surface area and morphology of hydration products during the early age of hydration. Therefore, natural pozzolanic volcanic ashes can be a viable substitute to Portland cement by providing environmental benefits in terms of lower-carbon footprint along with long-term durability.« less

Platinum clusters supported in zeolite LTL: Influence of catalyst morphology on performance in n-hexane reforming

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

Jentoft, R.E.; Gates, B.C.; Tsapatsis, M.

KLTL zeolite-supported platinum catalysts were synthesized from aqueous tetraammineplatinum(II) nitrate solutions and nonacidic KLTL zeolite crystallites, including some with dimensions as little as 300 x 500 {angstrom}. The zeolite crystallites had various morphologies, some being predominantly disk-shaped particles and some predominantly mosaics of rod-like domains with a range of c-dimension lengths. The activity and selectivity of each catalyst were evaluated for dehydrocyclization of n-hexane in the presence of H{sub 2} to form predominantly benzene at conversions of typically 45--90%. The data presented here provide a detailed characterization of the deactivation of such catalysts in the absence of sulfur. EXAFS datamore » show that the platinum in each catalyst was present in clusters of about 20 atoms each, on average. Electron micrographs show that the platinum clusters were nearly evenly dispersed on the surfaces of the zeolite crystallites, including the intracrystalline and extracrystalline surfaces. The catalytic performance was virtually independent of the zeolite channel length, but activity, selectivity, and resistance to deactivation were found to be correlated with the ratio of the surface area external to the crystallite domains to that within the intracrystalline pores. The catalyst performance is dependent on this ratio (which is related to the zeolite morphology) as follows: in comparison with the others, the catalysts with the relatively low fractions of platinum outside the intracrystalline pores are more active, more selective for benzene formation, and more resistant to deactivation.« less

Hydration kinetics and morphology of cement pastes with pozzolanic volcanic ash studied via synchrotron-based techniques

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

Kupwade-Patil, Kunal; Chin, Stephanie; Ilavsky, Jan

Here, this study investigates the early ages of hydration behavior when basaltic volcanic ash was used as a partial substitute to ordinary Portland cement using ultra-small-angle X-ray scattering and wide-angle X-ray scattering (WAXS). The mix design consisted of 10, 30 and 50% substitution of Portland cement with two different-sized volcanic ashes. The data showed that substitution of volcanic ash above 30% results in excess unreacted volcanic ash, rather than additional pozzolanic reactions along longer length scales. WAXS studies revealed that addition of finely ground volcanic ash facilitated calcium-silicate-hydrate related phases, whereas inclusion of coarser volcanic ash caused domination by calcium-aluminum-silicate-hydratemore » and unreacted MgO phases, suggesting some volcanic ash remained unreacted throughout the hydration process. Addition of more than 30% volcanic ash leads to coarser morphology along with decreased surface area and higher intensity of scattering at early-age hydration. This suggests an abrupt dissolution indicated by changes in surface area due to the retarding gel formation that can have implication on early-age setting influencing the mechanical properties of the resulting cementitious matrix. The findings from this work show that the concentration of volcanic ash influences the specific surface area and morphology of hydration products during the early age of hydration. Therefore, natural pozzolanic volcanic ashes can be a viable substitute to Portland cement by providing environmental benefits in terms of lower-carbon footprint along with long-term durability.« less

Mild chemical strategy to grow micro-roses and micro-woolen like arranged CuO nanosheets for high performance supercapacitors

NASA Astrophysics Data System (ADS)

Dubal, Deepak P.; Gund, Girish S.; Holze, Rudolf; Lokhande, Chandrakant D.

2013-11-01

The hierarchical structures of nanosheets, micro-roses and micro-woolen like CuO nanosheets were directly fabricated on stainless steel via surfactant-free and inexpensive chemical bath deposition (CBD) method. Further, these CuO nanostructures demonstrate excellent surface properties like uniform surface morphology, high surface area and uniform pore size distribution of CuO samples. The electrochemical properties of CuO nanostructures have been investigated by cyclic voltammetry, charge-discharge and electrochemical impedance spectroscopy techniques. The electrochemical studies of the CuO samples show obvious influence of surface properties on the pseudocapacitance performance. The maximum specific capacitances of nanosheets, micro-roses and micro-woolen like CuO nanosheets are found to be 303 Fg-1, 279 Fg-1 and 346 Fg-1, respectively at 5 mV s-1 scan rate. Further, the EIS analysis shows lower ESR value, high power performance, excellent rate as well as frequency response of micro-woolen like CuO sample. The Ragone plot ascertains better power and energy densities of all three CuO nanostructured samples than other electrical energy storage devices. The long-term cycling performance of CuO is examined at different scan rates and the morphology changes of the electrode materials were studied. Present investigation suggests the inexpensive CBD approach for fine-tuning surface properties of oxide materials for energy storage applications.

A novel approach for quantitative evaluation of the physicochemical interactions between rough membrane surface and sludge foulants in a submerged membrane bioreactor.

PubMed

Lin, Hongjun; Zhang, Meijia; Mei, Rongwu; Chen, Jianrong; Hong, Huachang

2014-11-01

This study proposed a novel approach for quantitative evaluation of the physicochemical interactions between a particle and rough surface. The approach adopts the composite Simpson's rule to numerically calculate the double integrals in the surface element integration of these physicochemical interactions. The calculation could be achieved by a MATLAB program based on this approach. This approach was then applied to assess the physicochemical interactions between rough membrane surface and sludge foulants in a submerged membrane bioreactor (MBR). The results showed that, as compared with smooth membrane surface, rough membrane surface had a much lower strength of interactions with sludge foulants. Meanwhile, membrane surface morphology significantly affected the strength and properties of the interactions. This study showed that the newly developed approach was feasible, and could serve as a primary tool for investigating membrane fouling in MBRs. Copyright © 2014 Elsevier Ltd. All rights reserved.

Investigations of morphological features of picosecond dual-wavelength laser ablation of stainless steel

NASA Astrophysics Data System (ADS)

Zhao, Wanqin; Wang, Wenjun; Mei, Xuesong; Jiang, Gedong; Liu, Bin

2014-06-01

Investigations on the morphological features of holes and grooves ablated on the surface of stainless steel using the picosecond dual-wavelength laser system with different powers combinations are presented based on the scarce researches on morphology of dual-wavelength laser ablation. The experimental results show the profiles of holes ablated by the visible beam appear V-shaped while those for the near-infrared have large openings and display U-shaped, which are independent of the ablation mechanism of ultrafast laser. For the dual-wavelength beam (a combination of visible beam and near-infrared), the holes resemble sunflower-like structures and have smoother ring patterns on the bottom. In general, the holes ablated by the dual-wavelength beam appear to have much flatter bottoms, linearly sloped side-walls and spinodal structures between the bottoms of the holes and the side-walls. Furthermore, through judiciously combining the powers of the dual-wavelength beam, high-quality grooves could be obtained with a flat worm-like structure at the bottom surface and less resolidified melt ejection edges. This study provides insight into optimizing ultrafast laser micromachining in order to obtain desired morphology.

Morphology and Growth Kinetics of Straight and Kinked Tin Whiskers

NASA Astrophysics Data System (ADS)

Susan, Donald; Michael, Joseph; Grant, Richard P.; McKenzie, Bonnie; Yelton, W. Graham

2013-03-01

Time-lapse SEM studies of Sn whiskers were conducted to estimate growth kinetics and document whisker morphologies. For straight whiskers, growth rates of 3 to 4 microns per day were measured at room temperature. Two types of kinked whiskers were observed. For Type A kinks, the original growth segment spatial orientation remains unchanged, there are no other changes in morphology or diameter, and growth continues. For Type B kinks, the spatial orientation of the original segment changes and it appears that the whisker bends over. Whiskers with Type B kinks show changes in morphology and diameter at the base, indicating grain boundary motion in the film, which eliminates the conditions suitable for long-term whisker growth. To estimate the errors in the whisker growth measurements, a technique is presented to correct for SEM projection effects. With this technique, the actual growth angles and lengths of a large number of whiskers were collected. It was found that most whiskers grow at moderate or shallow angles with respect to the surface; few straight whiskers grow nearly normal to the surface. In addition, there is no simple correlation between growth angles and lengths for whiskers observed over an approximate 2-year period.

Porous Silicon Covered with Silver Nanoparticles as Surface-Enhanced Raman Scattering (SERS) Substrate for Ultra-Low Concentration Detection.

PubMed

Kosović, Marin; Balarin, Maja; Ivanda, Mile; Đerek, Vedran; Marciuš, Marijan; Ristić, Mira; Gamulin, Ozren

2015-12-01

Microporous and macro-mesoporous silicon templates for surface-enhanced Raman scattering (SERS) substrates were produced by anodization of low doped p-type silicon wafers. By immersion plating in AgNO3, the templates were covered with silver metallic film consisting of different silver nanostructures. Scanning electron microscopy (SEM) micrographs of these SERS substrates showed diverse morphology with significant difference in an average size and size distribution of silver nanoparticles. Ultraviolet-visible-near-infrared (UV-Vis-NIR) reflection spectroscopy showed plasmonic absorption at 398 and 469 nm, which is in accordance with the SEM findings. The activity of the SERS substrates was tested using rhodamine 6G (R6G) dye molecules and 514.5 nm laser excitation. Contrary to the microporous silicon template, the SERS substrate prepared from macro-mesoporous silicon template showed significantly broader size distribution of irregular silver nanoparticles as well as localized surface plasmon resonance closer to excitation laser wavelength. Such silver morphology has high SERS sensitivity that enables ultralow concentration detection of R6G dye molecules up to 10(-15) M. To our knowledge, this is the lowest concentration detected of R6G dye molecules on porous silicon-based SERS substrates, which might even indicate possible single molecule detection.

Anti-biofilm efficacy of 100 MeV gold ion irradiated polycarbonate against Salmonella typhi

NASA Astrophysics Data System (ADS)

Joshi, R. P.; Hareesh, K.; Bankar, A.; Sanjeev, G.; Asokan, K.; Kanjilal, D.; Dahiwale, S. S.; Bhoraskar, V. N.; Dhole, S. D.

2017-12-01

Polycarbonate (PC) films were irradiated by 100 MeV gold (Au7+) ions and characterized to study changes in its optical, chemical, surface morphology and thermal properties. UV-Visible spectroscopic results revealed the decrease in the optical band gap of PC after ion irradiation due to chain scission mainly at the carbonyl group which is corroborated by Fourier Transform Infrared spectroscopic results. X-ray diffractogram study showed decrease in crystallinity of PC film after irradiation. Scanning electron microscopic results showed the micropores formation in PC which results in surface roughening. Differential scanning calorimetric results revealed decrease in glass transition temperature indicating the decrease in molecular weight of PC corroborated by rheometric studies. PC films irradiated by 100 MeV Au7+ ions showed increased anti-biofilm activity against the human pathogen, Salmonella typhi (S. typhi). Morphology of S. typhi was changed due to stress of Au7+ irradiated PC. Cells length was increased with increasing fluences. The average cell length, cell volume and surface area was increased significantly (P<0.05) with increasing ion fluences. Biofilm formation was inhibited ≈ 20% at lower fluence and 96% at higher fluence, which observed to be enhanced anti-biofilm activity in Au7+ irradiated PC.

Patterning of Biomolecules on Plasma-Enhanced Chemical Vapor Deposited Generated Surfaces

DTIC Science & Technology

2006-01-01

utilized conventional 1 -Ethyl- 3 -[ 3 - dimethylaminopropyl ]carbodiimide hydrochloride (EDC) to couple carboxyl groups to primary amines and thiol oxidation...RETURN YOUR FORM TO THE ABOVE ADDRESS. 1 . REPORT DATE (DD-MM-YY) 2. REPORT TYPE 3 . DATES COVERED (From - To) January 2006 Journal Article Preprint...morphology, allowing for robust surface deposited 3 materials. More specifically, bulk pp-benzene shows less than 1 % sol fraction when immersed in

Development of nanostructured ZnO thin film via electrohydrodynamic atomization technique and its photoconductivity characteristics.

PubMed

Duraisamy, Navaneethan; Kwon, Ki Rin; Jo, Jeongdai; Choi, Kyung-Hyun

2014-08-01

This article presents the non-vacuum technique for the preparation of nanostructured zinc oxide (ZnO) thin film on glass substrate through electrohydrodynamic atomization (EHDA) technique. The detailed process parameters for achieving homogeneous ZnO thin films are clearly discussed. The crystallinity and surface morphology of ZnO thin film are investigated by X-ray diffraction and field emission scanning electron microscopy. The result shows that the deposited ZnO thin film is oriented in the wurtzite phase with void free surface morphology. The surface roughness of deposited ZnO thin film is found to be ~17.8 nm. The optical properties of nanostructured ZnO thin films show the average transmittance is about 90% in the visible region and the energy band gap is found to be 3.17 eV. The surface chemistry and purity of deposited ZnO thin films are analyzed by fourier transform infrared and X-ray photoelectron spectroscopy, conforming the presence of Zn-O in the deposited thin films without any organic moiety. The photocurrent measurement of nanostructured ZnO thin film is examined in the presence of UV light illumination with wavelength of 365 nm. These results suggest that the deposited nanostructured ZnO thin film through EHDA technique possess promising applications in the near future.

Self-Healing Thermal Annealing: Surface Morphological Restructuring Control of GaN Nanorods

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

Conroy, Michele; Li, Haoning; Zubialevich, Vitaly Z.

With advances in nanolithography and dry etching, top-down methods of nanostructuring have become a widely used tool for improving the efficiency of optoelectronics. These nano dimensions can offer various benefits to the device performance in terms of light extraction and efficiency, but often at the expense of emission color quality. Broadening of the target emission peak and unwanted yellow luminescence are characteristic defect-related effects due to the ion beam etching damage, particularly for III–N based materials. In this article we focus on GaN based nanorods, showing that through thermal annealing the surface roughness and deformities of the crystal structure canmore » be “self-healed”. Correlative electron microscopy and atomic force microscopy show the change from spherical nanorods to faceted hexagonal structures, revealing the temperature-dependent surface morphology faceting evolution. The faceted nanorods were shown to be strain- and defect-free by cathodoluminescence hyperspectral imaging, micro-Raman, and transmission electron microscopy (TEM). In-situ TEM thermal annealing experiments allowed for real time observation of dislocation movements and surface restructuring observed in ex-situ annealing TEM sampling. This thermal annealing investigation gives new insight into the redistribution path of GaN material and dislocation movement post growth, allowing for improved understanding and in turn advances in optoelectronic device processing of compound semiconductors.« less

The effect of silver or gallium doped titanium against the multidrug resistant Acinetobacter baumannii.

PubMed

Cochis, A; Azzimonti, B; Della Valle, C; De Giglio, E; Bloise, N; Visai, L; Cometa, S; Rimondini, L; Chiesa, R

2016-02-01

Implant-related infection of biomaterials is one of the main causes of arthroplasty and osteosynthesis failure. Bacteria, such as the rapidly-emerging Multi Drug Resistant (MDR) pathogen Acinetobacter Baumannii, initiate the infection by adhering to biomaterials and forming a biofilm. Since the implant surface plays a crucial role in early bacterial adhesion phases, titanium was electrochemically modified by an Anodic Spark Deposition (ASD) treatment, developed previously and thought to provide osseo-integrative properties. In this study, the treatment was modified to insert gallium or silver onto the titanium surface, to provide antibacterial properties. The material was characterized morphologically, chemically, and mechanically; biological properties were investigated by direct cytocompatibility assay, Alkaline Phosphatase (ALP) activity, Scanning Electron Microscopy (SEM), and Immunofluorescent (IF) analysis; antibacterial activity was determined by counting Colony Forming Units, and viability assay. The various ASD-treated surfaces showed similar morphology, micrometric pore size, and uniform pore distribution. Of the treatments studied, gallium-doped specimens showed the best ALP synthesis and antibacterial properties. This study demonstrates the possibility of successfully doping the surface of titanium with gallium or silver, using the ASD technique; this approach can provide antibacterial properties and maintain high osseo-integrative potential. Copyright © 2015 Elsevier Ltd. All rights reserved.

In-situ growth of ZIF-8 on layered double hydroxide: Effect of Zn/Al molar ratios on their structural, morphological and adsorption properties.

PubMed

Yang, Yingli; Yan, Xinlong; Hu, Xiaoyan; Feng, Rui; Zhou, Min

2017-11-01

In-situ growth of Zeolite imidazolate frameworks (ZIFs) on layered double hydroxides (LDHs) to form porous composites is a promising and challenging strategy to develop materials for separation application. Herein, the Zn-Al LDH with different Zn/Al molar ratios was prepared and used as matrix for the growth of ZIF-8 on its surface. The resulting composites were characterized by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), N 2 physisorption, thermogravimetric (TG), scanning electron microscope (SEM) and elemental analysis followed by testing for As V removal from aqueous solution. Results showed that ZIF-8 could form on the surface of LDH with different Zn/Al molar ratios. At low Zn/Al molar ratios, the morphology and surface area of the ZIF/LDH composites and the content of ZIF-8 in the composites were little affected by the Zn/Al molar ratio. With increasing Zn/Al molar ratio, ZIF-8/LDH exhibited a lower surface area, which resulted from reduced content of ZIF-8 caused by impurities generated in the LDH matrix. All ZIF-8/LDH samples showed high As V adsorption capacity, which was significantly higher than that of pure LDH or ZIF-8. Copyright © 2017 Elsevier Inc. All rights reserved.

Development of Biomimetic and Functionally Responsive Surfaces

NASA Astrophysics Data System (ADS)

Anastasiadis, Spiros H.

2010-03-01

Controlling the surface morphology of solids and manufacturing of functional surfaces with special responsive properties has been the subject of intense research. We report a methodology for creating multifunctionally responsive surfaces by irradiating silicon wafers with femtosecond laser pulses and subsequently coating them with different types of functional conformal coatings. Such surfaces exhibit controlled dual-scale roughness at the micro- and the nano-scale, which mimics the hierarchical morphology of water repellent natural surfaces. When a simple alkylsilane coating is utilized, highly water repellent surfaces are produced that quantitatively compare to those of the Lotus leaf. When a polymer brush is ``grafted from" these surfaces based on a pH-sensitive polymer, the surfaces can alter their behavior from super-hydrophilic (after immersion in a low pH buffer) to super-hydrophobic and water-repellent (following immersion to a high pH buffer). We quantify the water repellency of such responsive systems by drop elasticity measurements whereas we demonstrate that the water repellent state of such surface requires appropriate hydrophobicity of the functionalizing polymer. When a photo-responsive azobenzene-type polymer is deposited, a dynamic optical control of the wetting properties is obtained and the surface can be switched from super-hydrophilic (following UV irradiation) to hydrophobic (following green irradiation). In all the above cases we show that the principal effect of roughness is to cause amplification of the response to the different external stimuli.

Morphological Evolution of Block Copolymer Particles: Effect of Solvent Evaporation Rate on Particle Shape and Morphology.

PubMed

Shin, Jae Man; Kim, YongJoo; Yun, Hongseok; Yi, Gi-Ra; Kim, Bumjoon J

2017-02-28

Shape and morphology of polymeric particles are of great importance in controlling their optical properties or self-assembly into unusual superstructures. Confinement of block copolymers (BCPs) in evaporative emulsions affords particles with diverse structures, including prolate ellipsoids, onion-like spheres, oblate ellipsoids, and others. Herein, we report that the evaporation rate of solvent from emulsions encapsulating symmetric polystyrene-b-polybutadiene (PS-b-PB) determines the shape and internal nanostructure of micron-sized BCP particles. A distinct morphological transition from the ellipsoids with striped lamellae to the onion-like spheres was observed with decreasing evaporation rate. Experiments and dissipative particle dynamics (DPD) simulations showed that the evaporation rate affected the organization of BCPs at the particle surface, which determined the final shape and internal nanostructure of the particles. Differences in the solvent diffusion rates in PS and PB at rapid evaporation rates induced alignment of both domains perpendicular to the particle surface, resulting in ellipsoids with axial lamellar stripes. Slower evaporation rates provided sufficient time for BCP organization into onion-like structures with PB as the outermost layer, owing to the preferential interaction of PB with the surroundings. BCP molecular weight was found to influence the critical evaporation rate corresponding to the morphological transition from ellipsoid to onion-like particles, as well as the ellipsoid aspect ratio. DPD simulations produced morphologies similar to those obtained from experiments and thus elucidated the mechanism and driving forces responsible for the evaporation-induced assembly of BCPs into particles with well-defined shapes and morphologies.

Effects of surface stability on the morphological transformation of metals and metal oxides as investigated by first-principles calculations.

PubMed

Andrés, Juan; Gracia, Lourdes; Gouveia, Amanda Fernandes; Ferrer, Mateus Meneghetti; Longo, Elson

2015-10-09

Morphology is a key property of materials. Owing to their precise structure and morphology, crystals and nanocrystals provide excellent model systems for joint experimental and theoretical investigations into surface-related properties. Faceted polyhedral crystals and nanocrystals expose well-defined crystallographic planes depending on the synthesis method, which allow for thoughtful investigations into structure-reactivity relationships under practical conditions. This feature article introduces recent work, based on the combined use of experimental findings and first-principles calculations, to provide deeper knowledge of the electronic, structural, and energetic properties controlling the morphology and the transformation mechanisms of different metals and metal oxides: Ag, anatase TiO2, BaZrO3, and α-Ag2WO4. According to the Wulff theorem, the equilibrium shapes of these systems are obtained from the values of their respective surface energies. These investigations are useful to gain further understanding of how to achieve morphological control of complex three-dimensional crystals by tuning the ratio of the surface energy values of the different facets. This strategy allows the prediction of possible morphologies for a crystal and/or nanocrystal by controlling the relative values of surface energies.

Analysis of carotid lumen surface morphology using three-dimensional ultrasound imaging

NASA Astrophysics Data System (ADS)

Chiu, Bernard; Beletsky, Vadim; Spence, J. David; Parraga, Grace; Fenster, Aaron

2009-03-01

Carotid plaque surface irregularity and ulcerations play an important role in the risk of ischemic stroke. Ulcerated or fissured plaque, characterized by irregular surface morphology, exposes thrombogenic materials to the bloodstream, possibly leading to life- or brain-threatening thrombosis and embolization. Therefore, the quantification of plaque surface irregularity is important to identify high-risk plaques that would likely lead to vascular events. Although a number of studies have characterized plaque surface irregularity using subjective classification schemes with two or more categories, only a few have quantified surface irregularity using an objective and continuous quantity, such as Gaussian or mean curvature. In this work, our goal was to use both Gaussian and mean curvatures for identifying ulcers from 3D carotid ultrasound (US) images of human subjects. Before performing experiments using patient data, we verified the numerical accuracy of the surface curvature computation method using discrete spheres and tori with different sampling intervals. We also showed that three ulcers of the vascular phantom with 2 mm, 3 mm and 4 mm diameters were associated with high Gaussian and mean curvatures, and thus, were easily detected. Finally, we demonstrated the application of the proposed method for detecting ulcers on luminal surfaces, which were segmented from the 3D US images acquired for two human subjects.

Surface Morphology and Hardness Analysis of TiCN Coated AA7075 Aluminium Alloy

NASA Astrophysics Data System (ADS)

Srinath, M. K.; Ganesha Prasad, M. S.

2017-12-01

Successful titanium carbonitride (TiCN) coating on AA7075 plates using the PVD technique depends upon many variables, including temperature, pressure, incident angle and energy of the reactive ions. Coated specimens have shown an increase in their surface hardness of 2.566 GPa. In this work, an attempt to further augment the surface hardness and understand its effects on the surface morphology was performed through heat treatments at 500°C for different duration of times. Specimen's heat treated at 500°C for 1 h exhibited a maximum surface hardness of 6.433 GPa, corresponding to an increase of 92.07%. The XRD results showed the presence of Al2Ti and AlTi3N and indicate the bond created between them. Unit cell lattice parameters in the XRD data are calculated using Bragg's law. The SEM images exhibit increasing crack sizes as the heat treatment time is increased. From the studies, the heat treatment duration can be optimized to 1 h, which exhibited an augmented surface hardness, as further increases in durations caused a drop in the surface hardness. The heat treatment effectively modified the surface hardness. Equations providing the relationships that temperature and time have with the reaction parameters are presented.

Effect of Shot Peening in Different Shot Distance and Shot Angle on Surface Morphology, Surface Roughness and Surface Hardness of 316L Biomaterial

NASA Astrophysics Data System (ADS)

Umbu Kondi Maliwemu, Erich; Malau, Viktor; Iswanto, Priyo Tri

2018-01-01

Shot peening is a mechanical surface treatment with a beneficial effect to generate compressive residual stress caused by plastic deformation on the surface of material. This plastic deformation can improve the surface characteristics of metallic materials, such as modification of surface morphology, surface roughness, and surface hardness. The objective of this study is to investigate the effect of shot peening in different shot distance and shot angle on surface morphology, surface roughness, and surface hardness of 316L biomaterial. Shot distance was varied at 6, 8, 10, and 12 cm and shot angle at 30, 60, and 90°, working pressure at 7 kg/cm2, shot duration for 20 minutes, and using steel balls S-170 with diameter of 0.6 mm. The results present that the shot distance and shot angle of shot peening give the significant effect to improve the surface morphology, surface roughness, and surface hardness of 316 L biomaterial. Shot peening can increase the surface roughness by the increasing of shot distance and by the decreasing of shot angle. The nearest shot distance (6 cm) and the largest shot angle (90°) give the best results on the grain refinement with the surface roughness of 1.04 μm and surface hardness of 534 kg/mm2.

Towards Enhanced Performance Thin-film Composite Membranes via Surface Plasma Modification

PubMed Central

Reis, Rackel; Dumée, Ludovic F.; Tardy, Blaise L.; Dagastine, Raymond; Orbell, John D.; Schutz, Jürg A.; Duke, Mikel C.

2016-01-01

Advancing the design of thin-film composite membrane surfaces is one of the most promising pathways to deal with treating varying water qualities and increase their long-term stability and permeability. Although plasma technologies have been explored for surface modification of bulk micro and ultrafiltration membrane materials, the modification of thin film composite membranes is yet to be systematically investigated. Here, the performance of commercial thin-film composite desalination membranes has been significantly enhanced by rapid and facile, low pressure, argon plasma activation. Pressure driven water desalination tests showed that at low power density, flux was improved by 22% without compromising salt rejection. Various plasma durations and excitation powers have been systematically evaluated to assess the impact of plasma glow reactions on the physico-chemical properties of these materials associated with permeability. With increasing power density, plasma treatment enhanced the hydrophilicity of the surfaces, where water contact angles decreasing by 70% were strongly correlated with increased negative charge and smooth uniform surface morphology. These results highlight a versatile chemical modification technique for post-treatment of commercial membrane products that provides uniform morphology and chemically altered surface properties. PMID:27363670

Abnormal growth kinetics of h-BN epitaxial monolayer on Ru(0001) enhanced by subsurface Ar species

NASA Astrophysics Data System (ADS)

Wei, Wei; Meng, Jie; Meng, Caixia; Ning, Yanxiao; Li, Qunxiang; Fu, Qiang; Bao, Xinhe

2018-04-01

Growth kinetics of epitaxial films often follows the diffusion-limited aggregation mechanism, which shows a "fractal-to-compact" morphological transition with increasing growth temperature or decreasing deposition flux. Here, we observe an abnormal "compact-to-fractal" morphological transition with increasing growth temperature for hexagonal boron nitride growth on the Ru(0001) surface. The unusual growth process can be explained by a reaction-limited aggregation (RLA) mechanism. Moreover, introduction of the subsurface Ar atoms has enhanced this RLA growth behavior by decreasing both reaction and diffusion barriers. Our work may shed light on the epitaxial growth of two-dimensional atomic crystals and help to control their morphology.

Can Cr( iii ) substitute for Al( iii ) in the structure of boehmite?

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

Chatterjee, Sayandev; Conroy, Michele A.; Smith, Frances N.

2016-01-01

The dissolution of boehmite is a technical issue for the Al industry because of its recalcitrant nature. In fact, a similar problem exists with boehmite in nuclear waste sludge at the Hanford site in eastern Washington State, USA. Dissolution of Al phases is required to reduce the waste loadings in the final borosilicate glass waste form. Although not the most common Al-bearing species in the sludge, boehmite may become a rate limiting step in the processing of the wastes. Hanford boehmite is an order of magnitude more resistant to dissolution in hot caustic solutions than expected from surface-normalized rates. Wemore » are exploring potential intrinsic and extrinsic effects that may limit boehmite reactivity; one clue comes from microstructural analyses that indicate an association of Cr with Al in the Hanford nuclear waste. Hence, in this first paper, we investigated the potential role of chromium on the reactivity of boehmite in caustic solution. An important finding was that irrespective of the synthesis pathway, amount of Cr(III), or the resultant morphology, there was no evidence for Cr incorporation in the bulk structure, in agreement with QM calculations. In fact, electron microscopic (EM) and spectroscopic analyses showed that Cr was enriched at the (101) edges of the boehmite. However, Cr had no measurable effect on the morphology during the synthesis step. In contrast, comparison of the morphologies of the synthetic Cr-doped and pure boehmite samples after exposure to caustic solutions provided evidence that Cr inhibited the corrosion. TEM showed that Cr was not homogeneously distributed at the surface. Consequently, Cr may have partially passivated the surface by blocking discrete energetic sites on the lateral surfaces of boehmite.« less

The interplay of plasma treatment and gold coating and ultra-high molecular weight polyethylene: On the cytocompatibility.

PubMed

Novotná, Zdenka; Rimpelová, Silvie; Juřík, Petr; Veselý, Martin; Kolská, Zdenka; Hubáček, Tomáš; Ruml, Tomáš; Švorčík, Václav

2017-02-01

We have investigated the application of Ar plasma for creation of nanostructured ultra high molecular weight polyethylene (PE) surface in order to enhance adhesion of mouse embryonic fibroblasts (L929). The aim of this study was to investigate the effect of the interface between plasma-treated and gold-coated PE on adhesion and spreading of cells. The surface properties of pristine samples and its modified counterparts were studied by different experimental techniques (gravimetry, goniometry and X-ray photoelectron spectroscopy (XPS), electrokinetic analysis), which were used for characterization of treated and sputtered layers, polarity and surface chemical structure, respectively. Further, atomic force microscopy (AFM) was employed to study the surface morphology and roughness. Biological responses of cells seeded on PE samples were evaluated in terms of cell adhesion, spreading, morphology and proliferation. Detailed cell morphology and intercellular connections were followed by scanning electron microscopy (SEM). As it was expected the thickness of a deposited gold film was an increasing function of the sputtering time. Despite the fact that plasma treatment proceeded in inert plasma, oxidized degradation products were formed on the PE surface which would contribute to increased hydrophilicity (wettability) of the plasma treated polymer. The XPS method showed a decrease in carbon concentration with increasing plasma treatment. Cell adhesion measured on the interface between plasma treated and gold coated PE was inversely proportional to the thickness of a gold layer on a sample. Copyright © 2016. Published by Elsevier B.V.

Manipulating mammalian cell morphologies using chemical-mechanical polished integrated circuit chips

NASA Astrophysics Data System (ADS)

Moussa, Hassan I.; Logan, Megan; Siow, Geoffrey C.; Phann, Darron L.; Rao, Zheng; Aucoin, Marc G.; Tsui, Ting Y.

2017-12-01

Tungsten chemical-mechanical polished integrated circuits were used to study the alignment and immobilization of mammalian (Vero) cells. These devices consist of blanket silicon oxide thin films embedded with micro- and nano-meter scale tungsten metal line structures on the surface. The final surfaces are extremely flat and smooth across the entire substrate, with a roughness in the order of nanometers. Vero cells were deposited on the surface and allowed to adhere. Microscopy examinations revealed that cells have a strong preference to adhere to tungsten over silicon oxide surfaces with up to 99% of cells adhering to the tungsten portion of the surface. Cells self-aligned and elongated into long threads to maximize contact with isolated tungsten lines as thin as 180 nm. The orientation of the Vero cells showed sensitivity to the tungsten line geometric parameters, such as line width and spacing. Up to 93% of cells on 10 μm wide comb structures were aligned within ± 20° of the metal line axis. In contrast, only 22% of cells incubated on 0.18 μm comb patterned tungsten lines were oriented within the same angular interval. This phenomenon is explained using a simple model describing cellular geometry as a function of pattern width and spacing, which showed that cells will rearrange their morphology to maximize their contact to the embedded tungsten. Finally, it was discovered that the materials could be reused after cleaning the surfaces, while maintaining cell alignment capability.

Manipulating mammalian cell morphologies using chemical-mechanical polished integrated circuit chips.

PubMed

Moussa, Hassan I; Logan, Megan; Siow, Geoffrey C; Phann, Darron L; Rao, Zheng; Aucoin, Marc G; Tsui, Ting Y

2017-01-01

Tungsten chemical-mechanical polished integrated circuits were used to study the alignment and immobilization of mammalian (Vero) cells. These devices consist of blanket silicon oxide thin films embedded with micro- and nano-meter scale tungsten metal line structures on the surface. The final surfaces are extremely flat and smooth across the entire substrate, with a roughness in the order of nanometers. Vero cells were deposited on the surface and allowed to adhere. Microscopy examinations revealed that cells have a strong preference to adhere to tungsten over silicon oxide surfaces with up to 99% of cells adhering to the tungsten portion of the surface. Cells self-aligned and elongated into long threads to maximize contact with isolated tungsten lines as thin as 180 nm. The orientation of the Vero cells showed sensitivity to the tungsten line geometric parameters, such as line width and spacing. Up to 93% of cells on 10 μm wide comb structures were aligned within ± 20° of the metal line axis. In contrast, only ~22% of cells incubated on 0.18 μm comb patterned tungsten lines were oriented within the same angular interval. This phenomenon is explained using a simple model describing cellular geometry as a function of pattern width and spacing, which showed that cells will rearrange their morphology to maximize their contact to the embedded tungsten. Finally, it was discovered that the materials could be reused after cleaning the surfaces, while maintaining cell alignment capability.

Manipulating mammalian cell morphologies using chemical-mechanical polished integrated circuit chips

PubMed Central

Moussa, Hassan I.; Logan, Megan; Siow, Geoffrey C.; Phann, Darron L.; Rao, Zheng; Aucoin, Marc G.; Tsui, Ting Y.

2017-01-01

Abstract Tungsten chemical-mechanical polished integrated circuits were used to study the alignment and immobilization of mammalian (Vero) cells. These devices consist of blanket silicon oxide thin films embedded with micro- and nano-meter scale tungsten metal line structures on the surface. The final surfaces are extremely flat and smooth across the entire substrate, with a roughness in the order of nanometers. Vero cells were deposited on the surface and allowed to adhere. Microscopy examinations revealed that cells have a strong preference to adhere to tungsten over silicon oxide surfaces with up to 99% of cells adhering to the tungsten portion of the surface. Cells self-aligned and elongated into long threads to maximize contact with isolated tungsten lines as thin as 180 nm. The orientation of the Vero cells showed sensitivity to the tungsten line geometric parameters, such as line width and spacing. Up to 93% of cells on 10 μm wide comb structures were aligned within ± 20° of the metal line axis. In contrast, only ~22% of cells incubated on 0.18 μm comb patterned tungsten lines were oriented within the same angular interval. This phenomenon is explained using a simple model describing cellular geometry as a function of pattern width and spacing, which showed that cells will rearrange their morphology to maximize their contact to the embedded tungsten. Finally, it was discovered that the materials could be reused after cleaning the surfaces, while maintaining cell alignment capability. PMID:29152017

Stick-slip friction and wear of articular joints

PubMed Central

Lee, Dong Woog; Banquy, Xavier; Israelachvili, Jacob N.

2013-01-01

Stick-slip friction was observed in articular cartilage under certain loading and sliding conditions and systematically studied. Using the Surface Forces Apparatus, we show that stick-slip friction can induce permanent morphological changes (a change in the roughness indicative of wear/damage) in cartilage surfaces, even under mild loading and sliding conditions. The different load and speed regimes can be represented by friction maps—separating regimes of smooth and stick-slip sliding; damage generally occurs within the stick-slip regimes. Prolonged exposure of cartilage surfaces to stick-slip sliding resulted in a significant increase of surface roughness, indicative of severe morphological changes of the cartilage superficial zone. To further investigate the factors that are conducive to stick-slip and wear, we selectively digested essential components of cartilage: type II collagen, hyaluronic acid (HA), and glycosaminoglycans (GAGs). Compared with the normal cartilage, HA and GAG digestions modified the stick-slip behavior and increased surface roughness (wear) during sliding, whereas collagen digestion decreased the surface roughness. Importantly, friction forces increased up to 2, 10, and 5 times after HA, GAGs, and collagen digestion, respectively. Also, each digestion altered the friction map in different ways. Our results show that (i) wear is not directly related to the friction coefficient but (ii) more directly related to stick-slip sliding, even when present at small amplitudes, and that (iii) the different molecular components of joints work synergistically to prevent wear. Our results also suggest potential noninvasive diagnostic tools for sensing stick-slip in joints. PMID:23359687

Morphological comparison of Astropecten cingulatus and a new species of Astropecten (Paxillosida, Astropectinidae) from the Gulf of Mexico.

PubMed

Lawrence, John M; Cobb, Janessa C; Herrera, Joan C; DurÁn-gonzÁlez, Alicia; SolÍs-marÍn, Francisco Alonso

2018-04-09

Astropecten cingulatus is a conspicuous species, which displays a large superomarginal plate series on the abactinal surface. Herein we describe a new species from off the Texas coast that shows the superficial appearance of A. cingulatus, including these large superomarginal plates, but with armature differing from that of typological A. cingulatus. This species shows the actinal surface of the inferomarginal plates without the squamules present on A. cingulatus. In addition, the adambulacral plates possessed but a single central large spine surrounded by a circle of spines rather than spine rows. The abactinal paxillar region was also very narrow. Statistical analysis of these and other morphological characters showed the specimens differed significantly from those of A. cingulatus. The regression of the slope of R:SM# vs. R was significant but the intercept was not. Therefore the two species are indistinguishable at small sizes based on R:SM. Compared to known Atlantic Astropecten spp. these observed characters warrant the description of a new species, Astropecten karankawai, for the specimens from off the coasts of Texas and Mexico.

McGET: A rapid image-based method to determine the morphological characteristics of gravels on the Gobi desert surface

NASA Astrophysics Data System (ADS)

Mu, Yue; Wang, Feng; Zheng, Bangyou; Guo, Wei; Feng, Yiming

2018-03-01

The relationship between morphological characteristics (e.g. gravel size, coverage, angularity and orientation) and local geomorphic features (e.g. slope gradient and aspect) of desert has been used to explore the evolution process of Gobi desert. Conventional quantification methods are time-consuming, inefficient and even prove impossible to determine the characteristics of large numbers of gravels. We propose a rapid image-based method to obtain the morphological characteristics of gravels on the Gobi desert surface, which is called the "morphological characteristics gained effectively technique" (McGET). The image of the Gobi desert surface was classified into gravel clusters and background by a machine-learning "classification and regression tree" (CART) algorithm. Then gravel clusters were segmented into individual gravel clasts by separating objects in images using a "watershed segmentation" algorithm. Thirdly, gravel coverage, diameter, aspect ratio and orientation were calculated based on the basic principles of 2D computer graphics. We validated this method with two independent datasets in which the gravel morphological characteristics were obtained from 2728 gravels measured in the field and 7422 gravels measured by manual digitization. Finally, we applied McGET to derive the spatial variation of gravel morphology on the Gobi desert along an alluvial-proluvial fan located in Hami, Xinjiang, China. The validated results show that the mean gravel diameter measured in the field agreed well with that calculated by McGET for large gravels (R2 = 0.89, P < 0.001). Compared to manual digitization, the McGET accuracies for gravel coverage, gravel diameter and aspect ratio were 97%, 83% and 96%, respectively. The orientation distributions calculated were consistent across two different methods. More importantly, McGET significantly shortens the time cost in obtaining gravel morphological characteristics in the field and laboratory. The spatial variation results show that the gravel coverage ranged from 88% to 65%, the gravel diameter was unimodally distributed and ranged from 19 mm to 13 mm. Most gravels were bladed or rod-like, with a mean aspect ratio of 1.57, and had no preferred orientation on the surveyed Gobi desert. From the center to the edge of the fan, gravel coverage decreased 2.2% per 100 m elevation decrease (R2 = 0.69, P < 0.001), mean gravel diameter decreased 0.5 mm per 100 m elevation decrease (R2 = 0.52, P < 0.001), and mean aspect ratio slightly increased 0.004 per 100 m elevation decrease (R2 = 0.26, P < 0.05). These results imply that surface washing was the main process on the investigated Gobi desert. This study demonstrates that the new method can quickly and accurately calculate the gravel coverage, diameter, aspect ratio and orientation from the images of Gobi desert.

Ultramorphology of the root surface subsequent to hand-ultrasonic simultaneous instrumentation during non-surgical periodontal treatments. An in vitro study

PubMed Central

D. ASPRIELLO, Simone; PIEMONTESE, Matteo; LEVRINI, Luca; SAURO, Salvatore

2011-01-01

Objective The purpose of this study was to investigate the ultramorphology of the root surfaces induced by mechanical instrumentation performed using conventional curettes or piezoelectric scalers when used single-handedly or with a combined technique. Material and Methods Thirty single-rooted teeth were selected and divided into 3 groups: Group A, instrumentation with curettes; Group B instrumentation with titanium nitride coated periodontal tip mounted in a piezoelectric handpiece; Group C, combined technique with curette/ultrasonic piezoelectric instrumentation. The specimens were processed and analyzed using confocal and scanning electron microscopy. Differences between the different groups of instrumentation were determined using Pearson’s χ 2 with significance predetermined at α=0.001. Results Periodontal scaling and root planing performed with curettes, ultrasonic or combined instrumentation induced several morphological changes on the root surface. The curettes produced a compact and thick multilayered smear layer, while the morphology of the root surfaces after ultrasonic scaler treatment appeared irregular with few grooves and a thin smear layer. The combination of curette/ultrasonic instrumentation showed exposed root dentin tubules with a surface morphology characterized by the presence of very few grooves and slender remnants of smear layer which only partially covered the root dentin. In some cases, it was also possible to observe areas with exposed collagen fibrils. Conclusion The curette-ultrasonic simultaneous instrumentation may combine the beneficial effects of each instrument in a single technique creating a root surface relatively free from the physical barrier of smear layer and dentin tubules orifices partial occlusion. PMID:21437474

Origin of collapsed pits and branched valleys surrounding the Ius chasma on Mars

NASA Astrophysics Data System (ADS)

Vamshi, G. T.; Martha, T. R.; Vinod Kumar, K.

2014-11-01

Chasma is a deep, elongated and steep sided depression on planetary surfaces. Several hypothesis have been proposed regarding the origin of chasma. In this study, we analysed morphological features in north and south of Ius chasma. Collapsed pits and branched valleys alongwith craters are prominent morphological features surrounding Ius Chasma, which forms the western part of the well known Valles Marineris chasma system on Martian surface. Analysis of images from the High Resolution Stereo Camera (HRSC) in ESA's Mars Express (MEX) with a spatial resolution of 10 m shows linear arrangement of pits north of the Ius chasma. These pits were initially developed along existing narrow linear valleys parallel to Valles Merineris and are conical in shape unlike flat floored impact craters found adjacent to them. The width of conical pits ranges 1-10 km and depth ranges 1-2 km. With more subsidence, size of individual pits increased gradually and finally coalesced together to create a large depression forming a prominent linear valley. Arrangement of pits in this particular fashion can be attributed to collapse of the surface due to l arge hollows created in the subsurface because of the withdrawal of either magma or dry ice. Branched valleys which are prominent morphologic features south of the Ius chasma could have been formed due to groundwater sapping mechanism as proposed by previous researchers. Episodic release of groundwater in large quantity to the surface could have resulted in surface runoff creating V-shaped valleys, which were later modified into U-shaped valleys due to mass wasting and lack of continued surface runoff.

Surface morphology of ultrathin graphene oxide films obtained by the SAW atomization

NASA Astrophysics Data System (ADS)

Balachova, Olga V.; Balashov, Sergey M.; Costa, Carlos A. R.; Pavani Filho, A.

2015-08-01

Lately, graphene oxide (GO) thin films have attracted much attention: they can be used as humidity-sensitive coatings in the surface acoustic wave (SAW) sensors; being functionalized, they can be used in optoelectronic or biodevices, etc. In this research we study surface morphology of small-area thin GO films obtained on Si and quartz substrates by deposition of very small amounts of H2O-GO aerosols produced by the SAW atomizer. An important feature of this method is the ability to work with submicrovolumes of liquids during deposition that provides relatively good control over the film thickness and quality, in particular, minimization of the coffee ring effect. The obtained films were examined using AFM and electron microscopy. Image analysis showed that the films consist of GO sheets of different geometry and sizes and may form discrete or continuous coatings at the surface of the substrates with the minimum thickness of 1.0-1.8 nm which corresponds to one or two monolayers of GO. The thickness and quality of the deposited films depend on the parameters of the SAW atomization (number of atomized droplets, a volume of the initial droplet, etc.) and on sample surface preparation (activation in oxygen plasma). We discuss the structure of the obtained films, uniformity and the surface coverage as a function of parameters of the film deposition process and sample preparation. Qualitative analysis of adhesion of GO films is made by rinsing the samples in DI water and subsequent evaluation of morphology of the remained films.

In-depth understanding of the relation between CuAlO₂ particle size and morphology for ozone gas sensor detection at a nanoscale level.

PubMed

Thirumalairajan, S; Mastelaro, Valmor R; Escanhoela, Carlos A

2014-12-10

A morphology-dependent nanomaterial for energy and environment applications is one of the key challenges for materials science and technology. In this study, we investigate the effect of the particle size of CuAlO2 nanostructures prepared through the facile and hydrothermal process to detect ozone gas. Phase analysis and structural information were obtained using X-ray diffraction and micro-Raman studies. The chemical states of CuAlO2 atomic species were determined by X-ray photoelectron spectroscopy. Electron microscopy images revealed the flower and hexagonal shape constituted of pentagon and oval CuAlO2 nanoparticles with average size ∼40 and 80 nm. The specific surface area was measured and found to be 59.8 and 70.8 m(2) g(-1), respectively. The developed CuAlO2 nanostructures not only possess unique morphology but also influence the ozone gas sensing performance. Among the two structures, CuAlO2, with hexagonal morphology, exhibited superior ozone detection for 200 ppb at 250 °C, with a response and good recovery time of 25 and 39 s compared to the flower morphology (28 and 69 s). These results show that not only does the morphology play an major role but also the particle size, surface area, gas adsorption/desorption, and grain-grain contact, as proposed in the gas sensing mechanism. Finally, we consider CuAlO2 material as a good candidate for environment monitoring applications.

Nano-Crystalline Diamond Films with Pineapple-Like Morphology Grown by the DC Arcjet vapor Deposition Method

NASA Astrophysics Data System (ADS)

Li, Bin; Zhang, Qin-Jian; Shi, Yan-Chao; Li, Jia-Jun; Li, Hong; Lu, Fan-Xiu; Chen, Guang-Chao

2014-08-01

A nano-crystlline diamond film is grown by the dc arcjet chemical vapor deposition method. The film is characterized by scanning electron microscopy, high-resolution transmission electron microscopy (HRTEM), x-ray diffraction (XRD) and Raman spectra, respectively. The nanocrystalline grains are averagely with 80 nm in the size measured by XRD, and further proven by Raman and HRTEM. The observed novel morphology of the growth surface, pineapple-like morphology, is constructed by cubo-octahedral growth zones with a smooth faceted top surface and coarse side surfaces. The as-grown film possesses (100) dominant surface containing a little amorphous sp2 component, which is far different from the nano-crystalline film with the usual cauliflower-like morphology.

Measurement of the surface morphology of plasma facing components on the EAST tokamak by a laser speckle interferometry approach

NASA Astrophysics Data System (ADS)

Hongbei, WANG; Xiaoqian, CUI; Yuanbo, LI; Mengge, ZHAO; Shuhua, LI; Guangnan, LUO; Hongbin, DING

2018-03-01

The laser speckle interferometry approach provides the possibility of an in situ optical non-contacted measurement for the surface morphology of plasma facing components (PFCs), and the reconstruction image of the PFC surface morphology is computed by a numerical model based on a phase unwrapping algorithm. A remote speckle interferometry measurement at a distance of three meters for real divertor tiles retired from EAST was carried out in the laboratory to simulate a real detection condition on EAST. The preliminary surface morphology of the divertor tiles was well reproduced by the reconstructed geometric image. The feasibility and reliability of this approach for the real-time measurement of PFCs have been demonstrated.

2D Thermoluminescence imaging of dielectric surface long term charge memory of plasma surface interaction in DBD discharges

NASA Astrophysics Data System (ADS)

Ambrico, Paolo F.; Ambrico, Marianna; Schiavulli, Luigi; De Benedictis, Santolo

2014-07-01

The charge trapping effect due to the exposure of alumina surfaces to plasma has been studied in a volume dielectric barrier discharge (DBD) in Ar and He noble gases. The long lasting charge trapping of alumina dielectric plates, used as barriers in DBDs, is evidenced by an ex situ thermoluminescence (TL) experiment performed with a standard and a custom two-dimensional (2D)-TL apparatus. The spatial density of trapped surface charges is found to be strongly correlated to the plasma morphology, and the surface spatial memory lasted for several minutes to hours after plasma exposure. In the case of Ar, the plasma channel impact signature on the surface shows a higher equivalent radiation dose with respect to the surface plasma wave and the post-discharge species signature. As a consequence, for the development of discharges, inside the dielectric surface the availability of lower energy trapped electrons is larger in the first region of plasma impact. The reported spatial memory increases the likelihood of the occurrence of plasma filaments in the same position in different runs. In He plasmas, the dielectric barrier shows an almost uniform distribution of trapped charges, meaning that there is no preferred region for the development of the discharge. In all cases a slight asymmetry was shown in the direction of the gas flow. This can be interpreted as being due to the long-living species moving in the direction of the gas flow, corresponding with the TL side experiment on the sample exposed to the plasma afterglow. The maximum values and the integral of the 2D-TL images showed a linear relation with the total charge per ac cycle, corresponding with findings for the TL glow curve. In conclusion, 2D-TL images allow the retrieval of information regarding the plasma surface interaction such as the plasma morphology, trap sites and their activation temperature.

Morpho-z: improving photometric redshifts with galaxy morphology

NASA Astrophysics Data System (ADS)

Soo, John Y. H.; Moraes, Bruno; Joachimi, Benjamin; Hartley, William; Lahav, Ofer; Charbonnier, Aldée; Makler, Martín; Pereira, Maria E. S.; Comparat, Johan; Erben, Thomas; Leauthaud, Alexie; Shan, Huanyuan; Van Waerbeke, Ludovic

2018-04-01

We conduct a comprehensive study of the effects of incorporating galaxy morphology information in photometric redshift estimation. Using machine learning methods, we assess the changes in the scatter and outlier fraction of photometric redshifts when galaxy size, ellipticity, Sérsic index, and surface brightness are included in training on galaxy samples from the SDSS and the CFHT Stripe-82 Survey (CS82). We show that by adding galaxy morphological parameters to full ugriz photometry, only mild improvements are obtained, while the gains are substantial in cases where fewer passbands are available. For instance, the combination of grz photometry and morphological parameters almost fully recovers the metrics of 5-band photometric redshifts. We demonstrate that with morphology it is possible to determine useful redshift distribution N(z) of galaxy samples without any colour information. We also find that the inclusion of quasar redshifts and associated object sizes in training improves the quality of photometric redshift catalogues, compensating for the lack of a good star-galaxy separator. We further show that morphological information can mitigate biases and scatter due to bad photometry. As an application, we derive both point estimates and posterior distributions of redshifts for the official CS82 catalogue, training on morphology and SDSS Stripe-82 ugriz bands when available. Our redshifts yield a 68th percentile error of 0.058(1 + z), and a outlier fraction of 5.2 per cent. We further include a deep extension trained on morphology and single i-band CS82 photometry.

Global morphological analysis of marine viruses shows minimal regional variation and dominance of non-tailed viruses.

PubMed

Brum, Jennifer R; Schenck, Ryan O; Sullivan, Matthew B

2013-09-01

Viruses influence oceanic ecosystems by causing mortality of microorganisms, altering nutrient and organic matter flux via lysis and auxiliary metabolic gene expression and changing the trajectory of microbial evolution through horizontal gene transfer. Limited host range and differing genetic potential of individual virus types mean that investigations into the types of viruses that exist in the ocean and their spatial distribution throughout the world's oceans are critical to understanding the global impacts of marine viruses. Here we evaluate viral morphological characteristics (morphotype, capsid diameter and tail length) using a quantitative transmission electron microscopy (qTEM) method across six of the world's oceans and seas sampled through the Tara Oceans Expedition. Extensive experimental validation of the qTEM method shows that neither sample preservation nor preparation significantly alters natural viral morphological characteristics. The global sampling analysis demonstrated that morphological characteristics did not vary consistently with depth (surface versus deep chlorophyll maximum waters) or oceanic region. Instead, temperature, salinity and oxygen concentration, but not chlorophyll a concentration, were more explanatory in evaluating differences in viral assemblage morphological characteristics. Surprisingly, given that the majority of cultivated bacterial viruses are tailed, non-tailed viruses appear to numerically dominate the upper oceans as they comprised 51-92% of the viral particles observed. Together, these results document global marine viral morphological characteristics, show that their minimal variability is more explained by environmental conditions than geography and suggest that non-tailed viruses might represent the most ecologically important targets for future research.

Inactivation of chemical and heat-resistant spores of Bacillus and Geobacillus by nitrogen cold atmospheric plasma evokes distinct changes in morphology and integrity of spores.

PubMed

van Bokhorst-van de Veen, Hermien; Xie, Houyu; Esveld, Erik; Abee, Tjakko; Mastwijk, Hennie; Nierop Groot, Masja

2015-02-01

Bacterial spores are resistant to severe conditions and form a challenge to eradicate from food or food packaging material. Cold atmospheric plasma (CAP) treatment is receiving more attention as potential sterilization method at relatively mild conditions but the exact mechanism of inactivation is still not fully understood. In this study, the biocidal effect by nitrogen CAP was determined for chemical (hypochlorite and hydrogen peroxide), physical (UV) and heat-resistant spores. The three different sporeformers used are Bacillus cereus a food-borne pathogen, and Bacillus atrophaeus and Geobacillus stearothermophilus that are used as biological indicators for validation of chemical sterilization and thermal processes, respectively. The different spores showed variation in their degree of inactivation by applied heat, hypochlorite, hydrogen peroxide, and UV treatments, whereas similar inactivation results were obtained with the different spores treated with nitrogen CAP. G. stearothermophilus spores displayed high resistance to heat, hypochlorite, hydrogen peroxide, while for UV treatment B. atrophaeus spores are most tolerant. Scanning electron microscopy analysis revealed distinct morphological changes for nitrogen CAP-treated B. cereus spores including etching effects and the appearance of rough spore surfaces, whereas morphology of spores treated with heat or disinfectants showed no such changes. Moreover, microscopy analysis revealed CAP-exposed B. cereus spores to turn phase grey conceivably because of water influx indicating damage of the spores, a phenomenon that was not observed for non-treated spores. In addition, data are supplied that exclude UV radiation as determinant of antimicrobial activity of nitrogen CAP. Overall, this study shows that nitrogen CAP treatment has a biocidal effect on selected Bacillus and Geobacillus spores associated with alterations in spore surface morphology and loss of spore integrity. Copyright © 2014 Elsevier Ltd. All rights reserved.

Thin-walled nanoscrolls by multi-step intercalation from tubular halloysite-10 Å and its rearrangement upon peroxide treatment

NASA Astrophysics Data System (ADS)

Zsirka, Balázs; Horváth, Erzsébet; Szabó, Péter; Juzsakova, Tatjána; Szilágyi, Róbert K.; Fertig, Dávid; Makó, Éva; Varga, Tamás; Kónya, Zoltán; Kukovecz, Ákos; Kristóf, János

2017-03-01

Surface modification of the halloysite-10 Å mineral with tubular morphology can be achieved by slightly modified procedures developed for the delamination of kaolinite minerals. The resulting delaminated halloysite nanoparticles have unexpected surface/morphological properties that display, new potentials in catalyst development. In this work, a four-step intercalation/delamination procedure is described for the preparation of thin-walled nanoscrolls from the multi-layered hydrated halloysite mineral that consists of (1) intercalation of halloysite with potassium acetate, (2) replacement intercalation with ethylene glycol, (3) replacement intercalation with hexylamine, and (4) delamination with toluene. The intercalation steps were followed by X-ray diffraction, transmission electron microscopy, N2 adsorption-desorption, thermogravimetry, and infrared spectroscopy. Delamination eliminated the crystalline order and the crystallite size along the 'c'-axis, increased the specific surface area, greatly decreased the thickness of the mineral tubes to a monolayer, and shifted the pore diameter toward the micropore region. Unexpectedly, the removal of residual organics from intercalation steps adsorbed at the nanoscroll surface with a peroxide treatment resulted in partial recovery of crystallinity and increase of crystallite size along the 'c'-crystal direction. The d(001) value showed a diffuse pattern at 7.4-7.7 Å due to the rearrangement of the thin-walled nanoscrolls toward the initial tubular morphology of the dehydrated halloysite-7 Å mineral.

Electrospun fiber surface nanotopography influences astrocyte-mediated neurite outgrowth.

PubMed

Johnson, Christopher D; D'Amato, Anthony R; Puhl, Devan L; Wich, Douglas M; Vespermann, Amanda; Gilbert, Ryan J

2018-05-15

Aligned, electrospun fiber scaffolds provide topographical guidance for regenerating neurons and glia after central nervous system injury. To date, no study has explored how fiber surface nanotopography affects astrocyte response to fibrous scaffolds. Astrocytes play important roles in the glial scar, the blood brain barrier, and in maintaining homeostasis in the central nervous system. In this study, electrospun poly L-lactic acid fibers were engineered with smooth, pitted, or divoted surface nanotopography. Cortical or spinal cord primary rat astrocytes were cultured on the surfaces for either 1 or 3 days to examine the astrocyte response over time. The results showed that cortical astrocytes were significantly shorter and broader on the pitted and divoted fibers compared to those on smooth fibers. However, spinal cord astrocyte morphology was not significantly altered by the surface features. These findings indicate that astrocytes from unique anatomical locations respond differently to the presence of nanotopography. Western Blot results show that the differences in morphology were not associated with significant changes in GFAP or vinculin in either astrocyte population, suggesting that surface pits and divots do not induce a reactive phenotype in either cortical or spinal cord astrocytes. Finally, astrocytes were co-cultured with dorsal root ganglia to determine how the surfaces affected astrocyte-mediated neurite outgrowth. Astrocytes cultured on the fibers for shorter periods of time (1 day) generally supported longer neurite outgrowth. Pitted and divoted fibers restricted spinal cord astrocyte-mediated neurite outgrowth, while smooth fibers increased 3 day spinal cord astrocyte-mediated neurite outgrowth. In total, fiber surface nanotopography can influence astrocyte elongation and influence the capability of astrocytes to direct neurites. Therefore, fiber surface characteristics should be carefully controlled to optimize astrocyte-mediated axonal regeneration. . © 2018 IOP Publishing Ltd.

Surface Texturing-Plasma Nitriding Duplex Treatment for Improving Tribological Performance of AISI 316 Stainless Steel

PubMed Central

Lin, Naiming; Liu, Qiang; Zou, Jiaojuan; Guo, Junwen; Li, Dali; Yuan, Shuo; Ma, Yong; Wang, Zhenxia; Wang, Zhihua; Tang, Bin

2016-01-01

Surface texturing-plasma nitriding duplex treatment was conducted on AISI 316 stainless steel to improve its tribological performance. Tribological behaviors of ground 316 substrates, plasma-nitrided 316 (PN-316), surface-textured 316 (ST-316), and duplex-treated 316 (DT-316) in air and under grease lubrication were investigated using a pin-on-disc rotary tribometer against counterparts of high carbon chromium bearing steel GCr15 and silicon nitride Si3N4 balls. The variations in friction coefficient, mass loss, and worn trace morphology of the tested samples were systemically investigated and analyzed. The results showed that a textured surface was formed on 316 after electrochemical processing in a 15 wt % NaCl solution. Grooves and dimples were found on the textured surface. As plasma nitriding was conducted on a 316 substrate and ST-316, continuous and uniform nitriding layers were successfully fabricated on the surfaces of the 316 substrate and ST-316. Both of the obtained nitriding layers presented thickness values of more than 30 μm. The nitriding layers were composed of iron nitrides and chromium nitride. The 316 substrate and ST-316 received improved surface hardness after plasma nitriding. When the tribological tests were carried out under dry sliding and grease lubrication conditions, the tested samples showed different tribological behaviors. As expected, the DT-316 samples revealed the most promising tribological properties, reflected by the lowest mass loss and worn morphologies. The DT-316 received the slightest damage, and its excellent tribological performance was attributed to the following aspects: firstly, the nitriding layer had high surface hardness; secondly, the surface texture was able to capture wear debris, store up grease, and then provide continuous lubrication. PMID:28773996

Physicochemical properties of calcium silicate-based formulations MTA Repair HP and MTA Vitalcem

PubMed Central

Guimarães, Bruno Martini; Prati, Carlo; Duarte, Marco Antonio Hungaro; Bramante, Clovis Monteiro; Gandolfi, Maria Giovanna

2018-01-01

Abstract Objective This study aimed to analyze the following physicochemical properties: radiopacity, final setting time, calcium release, pH change, solubility, water sorption, porosity, surface morphology, and apatite-forming ability of two calcium silicate-based materials. Material and methods We tested MTA Repair HP and MTA Vitalcem in comparison with conventional MTA, analyzing radiopacity and final setting time. Water absorption, interconnected pores and apparent porosity were measured after 24-h immersion in deionized water at 37°C. Calcium and pH were tested up to 28 d in deionized water. We analyzed data using two-way ANOVA with Student-Newman-Keuls tests (p<0.05). We performed morphological and chemical analyses of the material surfaces using ESEM/EDX after 28 d in HBSS. Results MTA Repair HP showed similar radiopacity to that of conventional MTA. All materials showed a marked alkalinizing activity within 3 h, which continued for 28 d. MTA Repair HP showed the highest calcium release at 28 d (p<0.05). MTA Vitalcem showed statistically higher water sorption and solubility values (p<0.05). All materials showed the ability to nucleate calcium phosphate on their surface after 28 d in HBSS. Conclusions MTA Repair HP and MTA Vitalcem had extended alkalinizing activity and calcium release that favored calcium phosphate nucleation. The presence of the plasticizer in MTA HP might increase its solubility and porosity. The radiopacifier calcium tungstate can be used to replace bismuth oxide. PMID:29641748

The biological response to laser-aided direct metal-coated Titanium alloy (Ti6Al4V)

PubMed Central

Shin, T.; Lim, D.; Kim, Y. S.; Kim, S. C.; Jo, W. L.

2018-01-01

Objectives Laser-engineered net shaping (LENS) of coated surfaces can overcome the limitations of conventional coating technologies. We compared the in vitro biological response with a titanium plasma spray (TPS)-coated titanium alloy (Ti6Al4V) surface with that of a Ti6Al4V surface coated with titanium using direct metal fabrication (DMF) with 3D printing technologies. Methods The in vitro ability of human osteoblasts to adhere to TPS-coated Ti6Al4V was compared with DMF-coating. Scanning electron microscopy (SEM) was used to assess the structure and morphology of the surfaces. Biological and morphological responses to human osteoblast cell lines were then examined by measuring cell proliferation, alkaline phosphatase activity, actin filaments, and RUNX2 gene expression. Results Morphological assessment of the cells after six hours of incubation using SEM showed that the TPS- and DMF-coated surfaces were largely covered with lamellipodia from the osteoblasts. Cell adhesion appeared similar in both groups. The differences in the rates of cell proliferation and alkaline phosphatase activities were not statistically significant. Conclusions The DMF coating applied using metal 3D printing is similar to the TPS coating, which is the most common coating process used for bone ingrowth. The DMF method provided an acceptable surface structure and a viable biological surface. Moreover, this method is automatable and less complex than plasma spraying. Cite this article: T. Shin, D. Lim, Y. S. Kim, S. C. Kim, W. L. Jo, Y. W. Lim. The biological response to laser-aided direct metal-coated Titanium alloy (Ti6Al4V). Bone Joint Res 2018;7:357–361. DOI: 10.1302/2046-3758.75.BJR-2017-0222.R1. PMID:29922456

Improved performance by morphology control via fullerenes in PBDT-TBT-alkoBT based organic solar cells

DOE PAGES

Khatiwada, Devendra; Venkatesan, Swaminathan; Chen, QIliang; ...

2015-07-03

In this work, we report improved performance by controlling morphology using different fullerene derivatives in poly{2-octyldodecyloxy-benzo[1,2-b;3,4-b]dithiophene-alt-5,6-bis(dodecyloxy)-4,7- di(thieno[3,2-b]thiophen-2-yl)-benzo[c][1,2,5]thiadiazole} (PBDT-TBT-alkoBT) based organic solar cells. PC60BM and PC70BM fullerenes were used to investigate the characteristic change in morphology and device performance. Fullerene affects device efficiency by changing active layer morphology. PC70BM with broader absorption than PC 60BM resulted in reduced device performance which was elucidated by the intermixed granular morphology separating each larger grain in the PC70BM/polymer composite layer which created higher density of traps. However after adding additive 1,8-diiodooctane (DIO), the fibrous morphology was observed due to reduced solubility of polymer andmore » increased solubility of PC 70BM in chloroform. The fibrous morphology improved charge transport leading to increase in overall device performance. Atomic force microscopies (AFM), photo induced charge extraction by linearly increasing voltage (photo-CELIV), and Kelvin prove force microscope (KPFM) were used to investigate nanoscale morphology of active layer with different fullerene derivatives. For PC 60BM based active layer, AFM images revealed dense fibrous morphology and more distinct fibrous morphology was observed by adding DIO. The PC 70BM based active layer only exhibited intermixed granular morphology instead of fibrous morphology observed in PC60BM based active layer. However, addition of DIO in PC 70BM based active layer led to fibrous morphology. When additive DIO was not used, a wider distribution of surface potential was observed for PC 70BM than PC 60BM based active layer by KPFM measurements, indicating 2 polymer and fullerene domains are separated. When DIO was used, narrower distribution of surface potential for both PC 70BM and PC 60BM based active layers was observed. Photo-CELIV experiment showed larger extracted charge carrier density and mobility in PC 70BM/DIO film.« less

Improved performance by morphology control via fullerenes in PBDT-TBT-alkoBT based organic solar cells

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

Khatiwada, Devendra; Venkatesan, Swaminathan; Chen, QIliang

In this work, we report improved performance by controlling morphology using different fullerene derivatives in poly{2-octyldodecyloxy-benzo[1,2-b;3,4-b]dithiophene-alt-5,6-bis(dodecyloxy)-4,7- di(thieno[3,2-b]thiophen-2-yl)-benzo[c][1,2,5]thiadiazole} (PBDT-TBT-alkoBT) based organic solar cells. PC60BM and PC70BM fullerenes were used to investigate the characteristic change in morphology and device performance. Fullerene affects device efficiency by changing active layer morphology. PC70BM with broader absorption than PC 60BM resulted in reduced device performance which was elucidated by the intermixed granular morphology separating each larger grain in the PC70BM/polymer composite layer which created higher density of traps. However after adding additive 1,8-diiodooctane (DIO), the fibrous morphology was observed due to reduced solubility of polymer andmore » increased solubility of PC 70BM in chloroform. The fibrous morphology improved charge transport leading to increase in overall device performance. Atomic force microscopies (AFM), photo induced charge extraction by linearly increasing voltage (photo-CELIV), and Kelvin prove force microscope (KPFM) were used to investigate nanoscale morphology of active layer with different fullerene derivatives. For PC 60BM based active layer, AFM images revealed dense fibrous morphology and more distinct fibrous morphology was observed by adding DIO. The PC 70BM based active layer only exhibited intermixed granular morphology instead of fibrous morphology observed in PC60BM based active layer. However, addition of DIO in PC 70BM based active layer led to fibrous morphology. When additive DIO was not used, a wider distribution of surface potential was observed for PC 70BM than PC 60BM based active layer by KPFM measurements, indicating 2 polymer and fullerene domains are separated. When DIO was used, narrower distribution of surface potential for both PC 70BM and PC 60BM based active layers was observed. Photo-CELIV experiment showed larger extracted charge carrier density and mobility in PC 70BM/DIO film.« less

Impact of uneven sample morphology on mass resolving power in linear MALDI-TOF mass spectrometry: A comprehensive theoretical investigation.

PubMed

Cai, Yi-Hong; Wang, Yi-Sheng

2018-04-01

This work discusses the correlation between the mass resolving power of matrix-assisted laser desorption/ionization time-of-flight mass analyzers and extraction condition with an uneven sample morphology. Previous theoretical calculations show that the optimum extraction condition for flat samples involves an ideal ion source design and extraction delay. A general expression of spectral feature takes into account ion initial velocity, and extraction delay is derived in the current study. The new expression extends the comprehensive calculation to uneven sample surfaces and above 90% Maxell-Boltzmann initial velocity distribution of ions to account for imperfect ionization condition. Calculation shows that the impact of uneven sample surface or initial spatial spread of ions is negligible when the extraction delay is away from the ideal value. When the extraction delay approaches the optimum value, the flight-time topology shows a characteristic curve shape, and the time-domain mass spectral feature broadens with an increase in initial spatial spread of ions. For protonated 2,5-dihydroxybenzoic acid, the mass resolving power obtained from a sample of 3-μm surface roughness is approximately 3.3 times lower than that of flat samples. For ions of m/z 3000 coexpanded with 2,5-dihydroxybenzoic acid, the mass resolving power in the 3-μm surface roughness case only reduces roughly 7%. Comprehensive calculations also show that the mass resolving power of lighter ions is more sensitive to the accuracy of the extraction delay than heavier ions. Copyright © 2018 John Wiley & Sons, Ltd.

Rough SERS substrate based on gold coated porous silicon layer prepared on the silicon backside surface

NASA Astrophysics Data System (ADS)

Dridi, H.; Haji, L.; Moadhen, A.

2017-04-01

We report in this paper a novel method to elaborate rough Surface Enhanced Raman Scattering (SERS) substrate. A single layer of porous silicon was formed on the silicon backside surface. Morphological characteristics of the porous silicon layer before and after gold deposition were influenced by the rough character (gold size). The reflectance measurements showed a dependence of the gold nano-grains size on the surface nature, through the Localized Surface Plasmon (LSP) band properties. SERS signal of Rhodamine 6G used as a model analyte, adsorbed on the rough porous silicon layer revealed a marked enhancement of its vibrational modes intensities.

Molecular beam epitaxy growth of high electron mobility InAs/AlSb deep quantum well structure

NASA Astrophysics Data System (ADS)

Wang, Juan; Wang, Guo-Wei; Xu, Ying-Qiang; Xing, Jun-Liang; Xiang, Wei; Tang, Bao; Zhu, Yan; Ren, Zheng-Wei; He, Zhen-Hong; Niu, Zhi-Chuan

2013-07-01

InAs/AlSb deep quantum well (QW) structures with high electron mobility were grown by molecular beam epitaxy (MBE) on semi-insulating GaAs substrates. AlSb and Al0.75Ga0.25Sb buffer layers were grown to accommodate the lattice mismatch (7%) between the InAs/AlSb QW active region and GaAs substrate. Transmission electron microscopy shows abrupt interface and atomic force microscopy measurements display smooth surface morphology. Growth conditions of AlSb and Al0.75Ga0.25Sb buffer were optimized. Al0.75Ga0.25Sb is better than AlSb as a buffer layer as indicated. The sample with optimal Al0.75Ga0.25Sb buffer layer shows a smooth surface morphology with root-mean-square roughness of 6.67 Å. The electron mobility has reached as high as 27 000 cm2/Vs with a sheet density of 4.54 × 1011/cm2 at room temperature.

Morphology of self assembled monolayers using liquid phase reaction on silica and their effect on the morphology of adsorbed insulin

NASA Astrophysics Data System (ADS)

Sharma, Indu; Pattanayek, Sudip K.; Aggarwal, Varsha; Ghosh, Subhasis

2017-05-01

The effect of roughness of two different categories of self-assembled monolayers (SAMs) with propyl amine and propyl groups respectively on the morphology of adsorbed insulin is observed. SAMs are obtained by liquid phase reaction of silica with organo silane coupling agents (SCA). The influence of the morphology and physical characteristics of the SAMs on the reaction time and concentration of the modifiers are explored. We have tested three SCA containing propyl amine with varying groups linked to Si present on it. In addition, we have used a silane coupling agent to prepare SAM of methyl head group. The approach of these molecules towards the surface depends on the head group and the groups linked to Si of the SCA. The morphology of the surfaces is analysed using power spectral density distribution (PSD), skewness, ellipsometry thickness and surface energy. Both chemical nature and physical morphology of the adsorbent influence the morphology of the adsorbed insulin. In general, a low number of aggregates of big size are formed on the surfaces obtained from low concentration of SAMs, while a higher number but of smaller size of aggregates are formed over surfaces obtained from 1% concentration of SAMs modifiers. The peak to valley ratio of the aggregates of insulin is strongly influenced by the size of grains of SCA over the adsorbent.

Metal-insulator transition properties of sputtered silicon-doped and un-doped vanadium dioxide films at terahertz range

NASA Astrophysics Data System (ADS)

Zhang, Huafu; Wu, Zhiming; Niu, Ruihua; Wu, Xuefei; he, Qiong; Jiang, Yadong

2015-03-01

Silicon-doped and un-doped vanadium dioxide (VO2) films were synthesized on high-purity single-crystal silicon substrates by means of reactive direct current magnetron sputtering followed by thermal annealing. The structure, morphology and metal-insulator transition properties of silicon-doped VO2 films at terahertz range were measured and compared to those of un-doped VO2 films. X-ray diffraction and scanning electron microscopy indicated that doping the films with silicon significantly affects the preferred crystallographic orientation and surface morphologies (grain size, pores and characteristics of grain boundaries). The temperature dependence of terahertz transmission shows that the transition temperature, hysteresis width and transition sharpness greatly depend on the silicon contents while the transition amplitude was relatively insensitive to the silicon contents. Interestingly, the VO2 film doped with a silicon content of 4.6 at.% shows excellent terahertz switching characteristics, namely a small hysteresis width of 4.5 °C, a giant transmission modulation ratio of about 82% and a relatively low transition temperature of 56.1 °C upon heating. This work experimentally indicates that silicon doping can effectively control not only the surface morphology but also the metal-insulator transition characteristics of VO2 films at terahertz range.

Single- and multi-pulse formation of surface structures under static femtosecond irradiation

NASA Astrophysics Data System (ADS)

Guillermin, M.; Garrelie, F.; Sanner, N.; Audouard, E.; Soder, H.

2007-07-01

Femtosecond surface structure modifications are investigated under irradiation with laser pulses of 150 fs at 800 nm, on copper and silicon. We report sub-wavelength periodic structures formation (ripples) with a periodicity of 500 nm for both materials. These ripples are perpendicular to the laser polarization and can be obtained with only one pulse. The formation of these ripples corresponds to a fluence threshold of 1 J/cm 2 for copper and 0.15 J/cm 2 for silicon. We find several morphologies when more pulses are applied: larger ripples parallel to the polarization are formed with a periodicity of 1 μm and degenerate into a worm-like morphology with a higher number of pulses. In addition, walls of deep holes also show sub-wavelength and large ripples.

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.

Gold surface plasmon crystal structure based-on polystyrene template for biosensor application.

PubMed

Cheng, Min-Zhuo; Zhang, Jing; Bao, Dequan; Huang, Xiwei

2018-05-21

In this communication, we assembled ordered polystyrene (PS) microsphere array as a template with the drop-coating method, and the oxygen plasma was used to etch the template to adjust the spacing between the PS microspheres. Nano-triangular gold array and silver nano-pyramid array were obtained by ion beam sputtering to deposit precious metal gold and silver. We observed the surface morphology of Au and Au/Ag composite films by scanning electron microscope and characterized the films by X-ray diffraction and ultraviolet/visible light spectrophotometer. The results show that the etching time of oxygen plasma has an obvious effect in adjusting the spacing between PSs and has a significant effect on the morphology of Au structure. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Microscopic structure and properties changes of cassava stillage residue pretreated by mechanical activation.

PubMed

Liao, Zhengda; Huang, Zuqiang; Hu, Huayu; Zhang, Yanjuan; Tan, Yunfang

2011-09-01

This study has focused on the pretreatment of cassava stillage residue (CSR) by mechanical activation (MA) using a self-designed stirring ball mill. The changes in surface morphology, functional groups and crystalline structure of pretreated CSR were examined by using scanning electron microscopy (SEM), Fourier transform infrared (FTIR) spectroscopy and X-ray diffraction (XRD) under reasonable conditions. The results showed that MA could significantly damage the crystal structure of CSR, resulting in the variation of surface morphology, the increase of amorphous region ratio and hydrogen bond energy, and the decrease in crystallinity and crystalline size. But no new functional groups generated during milling, and the crystal type of cellulose in CSR still belonged to cellulose I after MA. Copyright © 2011 Elsevier Ltd. All rights reserved.

Influence of gamma irradiation on the surface morphology, XRD and thermophysical properties of silicide hexoboride

NASA Astrophysics Data System (ADS)

Mirzayev, Matlab N.; Mehdiyeva, Ravan N.; Garibov, Ramin G.; Ismayilova, Narmin A.; Jabarov, Sakin H.

2018-05-01

In this study, compounds of B6Si were irradiated using a 60Co gamma source that have an energy line of 1.25 MeV at the absorbed dose rates from 14.6 kGy to 194.4 kGy. Surface morphology images of the sample obtained by Scanning Electron Microscope (SEM) show that the crystal structure at a high absorbed doses (D ≥ 145.8kGy) starts to be destroyed. X-ray diffraction studies revealed that with increasing radiation absorption dose, the spectrum intensity of the sample was decreased 1.96 times compared with the initial value. Thermal properties were studied by Differential scanning calorimetry (DSC) method in the temperature range of 30-1000∘C.

Synthesis of nano-structure tungsten nitride thin films on silicon using Mather-type plasma focus

NASA Astrophysics Data System (ADS)

Hussnain, A.; Rawat, R. S.; Ahmad, R.; Umar, Z. A.; Hussain, T.; Lee, P.; Chen, Z.

2015-07-01

Nano-structure thin film of tungsten nitride was deposited onto Si-substrate at room temperature using Mather-type plasma focus (3.3 kJ) machine. Substrate was exposed against 10, 20, 30, and 40 deposition shots and its corresponding effect on structure, morphology, conductivity and nano-hardness has been systematically studied. The X-ray diffractormeter spectra of the exposed samples show the presence of various phases of WN and WN2 that depends on number of deposition shots. Surface morphological study revealed the uniform distribution of nano-sized grains on deposited film surface. Hardness and conductivity of exposed substrate improved with higher deposition shots. X-ray photo-electron spectroscopy survey scan of 40 deposition shots confirmed the elemental presence of W and N on Si-substrate.

Deposition of Cubic AlN Films on MgO (100) Substrates by Laser Molecular Beam Epitaxy

NASA Astrophysics Data System (ADS)

Mo, Z. K.; Yang, W. J.; Weng, Y.; Fu, Y. C.; He, H.; Shen, X. M.

2017-12-01

Cubic AlN (c-AlN) films were deposited on MgO (100) substrates by laser molecular beam epitaxy (LMBE) technique. The crystal structure and surface morphology of deposited films with various laser pulse energy and substrate temperature were investigated. The results indicate that c-AlN films exhibit the (200) preferred orientation, showing a good epitaxial relationship with the substrate. The surface roughness of c-AlN films increases when the laser pulse energy and substrate temperature increase. The film grown at laser pulse energy of 150 mJ and substrate temperature of 700 °C shows the best crystalline quality and relatively smooth surface.

Sexual Dimorphisms of Appendicular Musculoskeletal Morphology Related to Social Display in Cuban Anolis Lizards.

PubMed

Anzai, Wataru; Cádiz, Antonio; Endo, Hideki

2015-10-01

In Anolis lizards, sexual dimorphism has been reported in morphological and ecological traits. Males show larger body size and longer limbs related to territorial combat and courtship display with the dewlap. Although functional-anatomical traits are closely related to locomotor behaviors, differences between sexes in musculoskeletal traits on limbs remain unclear. We explored the relationships among sexual dimorphisms in musculoskeletal morphology, habitat, and locomotor traits in Anolis lizards. Specifically, we examined appendicular musculoskeletal morphology in three species of Cuban Anolis by measuring muscle mass and lengths of moment arms. Through comparisons of crossing locomotion, we found that the runner species possessed larger extensors in hindlimbs, which are advantageous for running, whereas the masses of the humeral and femoral retractors were larger in climber species, allowing these lizards to hold up their bodies and occupy tree substrates. Comparisons between the sexes showed different trends among the three species. Males of A. porcatus, which inhabit narrow branches or leaves, had stronger elbow extensors that maintain the display posture. In contrast, males of A. sagrei, which occupy broad surfaces, did not show sexual differences that affected social display. Moreover, A. bartschi indicated sexual differences despite the absence of dewlapping behavior. Our findings suggest that both sexes show fundamentally similar relationships between muscular morphology and locomotor habits to adapt arboreal or terrestrial substrates, and yet sexual dimorphism in forelimb muscles may additionally affected by male specific display with the dewlap.

Morphology and digitally aided morphometry of the human paracentral lobule.

PubMed

Spasojević, Goran; Malobabic, Slobodan; Pilipović-Spasojević, Olivera; Djukić-Macut, Nataša; Maliković, Aleksandar

2013-02-01

The human paracentral lobule, the junction of the precentral and postcentral gyri at the medial hemispheric surface, contains several important functional regions, and its variable morphology requires exact morphological and quantitativedata. In order to obtain precise data we investigated the morphology of the paracentral lobule and quantified its visible (extrasulcal) surface. This surface corresponds to commonly used magnetic resonance imaging scout images. We studied 84 hemispheres of adult persons (42 brains; 26 males and 16 females; 20-65 years) fixed in neutral formalin for at least 4 weeks. The medial hemispheric surface was photographed at standard distance and each digital photo was calibrated. Using the intercommissural line system (commissura anterior-commissura posterior or CA-CP line), we performed standardised measurements of the paracentral lobule. Exact determination of its boundaries and morphological types was followed by digital morphometry of its extrasulcal surface using AutoCAD software. We found two distinct morphological types of the human paracentral lobule: continuous type, which was predominant (95.2%), and rare segmented type (4.8%). In hemispheres with segmented cingulate sulcus we also found the short transitional lobulo-limbic gyrus (13.1%). The mean extrasulcal surface of the left paracentral lobule was significantly larger, both in males (left 6.79 cm2 vs. right 5.76 cm2) and in females (left 6.05 cm2 vs. right 5.16 cm2). However, even larger average surfaces in males were not significantly different than the same in females. Reported morphological and quantitative data will be useful during diagnostics and treatment of pathologies affecting the human paracentral lobule, and in further studies of its cytoarchitectonic and functional parcellations.

Assessment of condylar morphology and position using MSCT in an Asian population.

PubMed

Liu, Qi; Wei, Xiaoer; Guan, Juanjuan; Wang, Ran; Zou, Derong; Yu, Lvfeng

2018-02-01

The purpose of the present study was to investigate the volume, surface, morphometric index (MI), and position of the condyle in a normal population by applying Mimics 17.0 software. Then, the difference between left and right sides, sex, and age can be explored, which will contribute to establish the reference value of condylar morphology and position in normal individuals, and help us to study characteristics of condylar morphology and position in abnormal individuals. Three-hundred subjects were enrolled in our study from the radiology department of Shanghai Jiao Tong University Affiliated Sixth People's Hospital. They were divided into three groups according to the age: group 1 (18-24 years old), group 2 (25-34 years old), and group 3 (35-44 years old). Each group included 100 subjects (with 50 males and 50 females). They were examined using multislice computed tomography (MSCT) after that. All images of condyle were reconstructed by Mimics 17.0 software, so as to measure the volume, surface, and MI of condyle, and to analyze the position of condyle in the articular fossa by means of joint spaces. The differences of condylar volume, surface, and MI between left and right sides were not obvious (P > 0.05). The condylar volume and surface were greater in males than females (P < 0.05), while their condylar MI existed no difference (P > 0.05). No statistical differences were found in volume and surface among three age groups. However, the MI of group 1 was statistically lower than that of group 3 (P < 0.05). On the other hand, no significant differences were found between left and right condylar position (P > 0.05). Nevertheless, there were significant differences of condylar position regarding the gender and age (P < 0.05). This study showed no significant differences in condylar morphology and position between left and right sides, but factors of gender and age were proven to have a certain influence on the morphology and position of the condyle. This information can be clinically useful in establishing the diagnostic criteria for condylar morphology and position in the normal Asian population. Examination of condylar morphology and position is important for evaluating the abnormalities and bony changes that affect the temporomandibular joint (TMJ). So, this will be conducive to the diagnosis and the evaluation of therapeutic effect of temporomandibular joint diseases. Also, it is important to evaluate these indexes prior to commencing orthodontic treatment, because TMJ abnormalities play a critical role in orthodontic treatment planning.

Ultrasonic vibration double scratch morphology and scratching force of BK7 glass

NASA Astrophysics Data System (ADS)

Wang, Chu; Wang, Hongxiang; Liu, Junliang; Gao, Shi

2018-03-01

In this paper, the damage morphology and scratching force of BK7 glass components were analyzed by ultrasonic vibration double-scratch test. The results showed that there was surface damage caused by plastic flow and brittle fracture during the scratching process, and the scratching depth and the distance between the two scratches had effect on the propagation and overlapping of lateral cracks. When the scratching depth was small, the jagged scratch was produced on the surface, and accompanied by a small amount of tiny pieces of debris off. With the increase in scratching depth, the lateral cracks caused by scratching overlapped and expended to form a mesh sheet, and then fell off from the surface. When the scratching distance was small, the interaction of the cracks caused large slice of material to fall off. With the increase in scratching distance, the area between the two scratches was not easy to occur the overlapping of the lateral cracks. In addition, with the increase of the scratching depth, the scratching force showed a gradual increase trend, and the scratching force of the second scratch would increase with the scratching distance.

Incorporation of Copper Enhances the Anti-Ageing Property of Flame-Sprayed High-Density Polyethylene Coatings

NASA Astrophysics Data System (ADS)

Jia, Zhengmei; Huang, Jing; Gong, Yongfeng; Jin, Peipeng; Suo, Xinkun; Li, Hua

2017-02-01

High-density polyethylene (HDPE)-copper (Cu) composite coatings were prepared through depositing HDPE-Cu core-shell particles by flame spraying. The HDPE-Cu composite coatings and the HDPE coatings were aged in xenon lamp ageing testing chamber. The variations of chemical compositions and surface morphology of the coatings before and after the ageing testing were analyzed using infrared spectroscopy, scanning electron microscopy, thermogravimetric analysis, differential scanning calorimetry and ultraviolet-visible spectrophotometer. Results show that there is no chemical composition variation in the HDPE-Cu coatings. Cracks were found on the surfaces of the HDPE coatings, while the HDPE-Cu coating shows almost intact surface morphology. These results suggest that the HDPE-Cu coatings present better anti-ageing performances than the HDPE coatings. Further assessment of the function of Cu shells on the anti-ageing property reveals that Cu shells not only enhanced the absorption of the coatings to ultraviolet, but also increased their reflectivity to visible light. Additionally, the Cu shells enhanced the decomposition temperature and thermal stability of HDPE in the composite coatings. These results give bright insight into potential anti-ageing applications of the polymer-based structures.

Effects of heat/citric acid reprocessing on high-flux polysulfone dialyzers.

PubMed

Cornelius, Rena M; McClung, W Glenn; Richardson, Robert M A; Estridge, Charles; Plaskos, Nicholas; Yip, Christopher M; Brash, John L

2002-01-01

The surface features, morphology, and tensile properties of fibers obtained from pristine, reprocessed, and reused Fresenius Polysulfone High-Flux (Hemoflow F80A) hemodialyzers have been studied. Scanning electron microscopy of the dialyzer fibers revealed a dense skin layer on the inner surface of the membrane and a relatively thick porous layer on the outer surface. Transmission electron microscopy and atomic force microscopy showed an alteration in membrane morphology due to reprocessing and reuse, or to a deposition of blood-borne material on the membrane that is not removed with reprocessing. Fluorescent microscopy images also showed that a fluorescent material not removed by heat/citric acid reprocessing builds up with continued use of the dialyzers. The tensile properties of the dialyzer fibers were not affected by the heat/citric acid reprocessing procedure. The protein layers formed on pristine and reused hemodialyzer membranes during clinical use were also studied using sodium dodecyl sulfate polyacrylamide gel electrophoresis and immunoblotting. A considerable amount of protein was found on the blood side of single and multiple use dialyzers. Proteins adsorbed on the dialysate side of the membrane were predominantly in the molecular weight region below 30 kDa. Little protein was detected on the membranes of reprocessed hemodialyzers.

Synthesis and characterization of Ni NPs-doped silica-titania nanocomposites: structural, optical and photocatalytic properties

NASA Astrophysics Data System (ADS)

Islam, S.; Bidin, N.; Osman, S. S.; Krishnan, G.; Salim, A. A.; Riaz, S.; Suan, L. P.; Naseem, S.; Sanagi, M. M.

2017-01-01

The synthesis of Ni-doped silica-titania nanocomposite is performed by sol-gel method. The samples prior and after heat treatment at 300 °C for 1 h are characterized by analytical instrumental techniques. FE-SEM and AFM results indicate the regular morphology with low surface roughness without any cracks. EDX analysis verifies the formation of nanocomposites. XRD of the films reveals crystalline titania phases after annealing at 300 °C. The FTIR confirms the bond linkage between silica, titania and nickel molecules. High surface area 155 m2/g, pore volume of 0.2 cm3/g and pore diameter of 48.10 Å are obtained after heat treatment. The magnetic results show that the composite content is reminiscent of ferromagnetic hysteresis loop, with remanence magnetization Mr of 45.35 and 13.20 emu/g for both samples. The organic dye phenol red is used for the evaluation of photocatalytic activity of the synthesized magnetic material. The homogeneous surface morphology, crystalline nature, good solubility of magnetic nanoparticles into the silica-titania matrix show that the Ni/SiO2-TiO2 magnetic photocatalyst can be efficient and reusable.

The effect of activation agent on surface morphology, density and porosity of palm shell and coconut shell activated carbon

NASA Astrophysics Data System (ADS)

Leman, A. M.; Zakaria, S.; Salleh, M. N. M.; Sunar, N. M.; Feriyanto, D.; Nazri, A. A.

2017-09-01

Activated carbon (AC) has one of the promising alternative technology for filtration and adsorption process. It inexpensive material because the sources is abundant especially in Malaysia. Main purpose of this project is to develop AC by chemical activation process to improve adsorption capacity by improving porosity of AC. AC developed via carbonization using designed burner at temperature of 650°C to 850 °C and activated by Potassium Hydroxide (KOH) in 12 hour and then dried at temperature of 300°C. Characterization and analysis is conducted by Scanning Electron Microscopy (SEM) for surface morphology analysis, Energy Dispersive Spectroscopy (EDS) for composition analysis, density and porosity analysis. Results shows that uneven surface has been observed both of AC and non-AC and also AC shows higher porosity as compared to non-AC materials. Density value of raw material has lower than AC up to 11.67% and 47.54% and porosity of raw material has higher than AC up to 31.45% and 45.69% for palm shell and coconut shell AC. It can be concluded that lower density represent higher porosity of material and higher porosity indicated higher adsorption capacity as well.

Effect of polyamide 6 on the morphology and electrical conductivity of carbon black-filled polypropylene composites

NASA Astrophysics Data System (ADS)

Zhang, Xuewei; Liu, Jiang; Wang, Yi; Wu, Wei

2017-12-01

Carbon black (CB)-filled polypropylene (PP) with surface resistivity between 106 and 109 Ω sq-1 is the ideal antistatic plastic material in the electronics and electric industry. However, a large amount of CB may have an adverse effect on the mechanical properties and processing performance of the material, thus an improved ternary system is developed. Blends of CB-filled PP and polyamide 6 (PA6) have been prepared by melt blending in order to obtain electrically conductive polymer composites with a low electrical percolation threshold based on the concept of double percolation. The morphological developments of these composites were studied by scanning electron microscopy. The results showed that CB particles were selectively dispersed in PA6 phases due to the good interaction and interfacial adhesion between CB and PA6. At the same CB loadings, the surface resistivity of PP/PA6/CB composite was smaller than that of PP/CB composite system, which indicated the better conductivity in the former composite. The increasing amount of PA6 in the composites changed the morphology from a typical sea-island morphology to a co-continuous morphology. What is more, with 8 wt% of CB and PP/PA6 phase ratio of 70/30 in which the PP and PA6 phases formed a co-continuous structure, the electrical conductivity of the composite peaked at 2.01 × 105 Ω sq-1.

Extracting hurricane eye morphology from spaceborne SAR images using morphological analysis

NASA Astrophysics Data System (ADS)

Lee, Isabella K.; Shamsoddini, Ali; Li, Xiaofeng; Trinder, John C.; Li, Zeyu

2016-07-01

Hurricanes are among the most destructive global natural disasters. Thus recognizing and extracting their morphology is important for understanding their dynamics. Conventional optical sensors, due to cloud cover associated with hurricanes, cannot reveal the intense air-sea interaction occurring at the sea surface. In contrast, the unique capabilities of spaceborne synthetic aperture radar (SAR) data for cloud penetration, and its backscattering signal characteristics enable the extraction of the sea surface roughness. Therefore, SAR images enable the measurement of the size and shape of hurricane eyes, which reveal their evolution and strength. In this study, using six SAR hurricane images, we have developed a mathematical morphology method for automatically extracting the hurricane eyes from C-band SAR data. Skeleton pruning based on discrete skeleton evolution (DSE) was used to ensure global and local preservation of the hurricane eye shape. This distance weighted algorithm applied in a hierarchical structure for extraction of the edges of the hurricane eyes, can effectively avoid segmentation errors by reducing redundant skeletons attributed to speckle noise along the edges of the hurricane eye. As a consequence, the skeleton pruning has been accomplished without deficiencies in the key hurricane eye skeletons. A morphology-based analyses of the subsequent reconstructions of the hurricane eyes shows a high degree of agreement with the hurricane eye areas derived from reference data based on NOAA manual work.

Corroded surface roughness of copper analyzed by Fourier transform infrared mapping microscopy and optical profilometric study.

PubMed

Kasperek, J; Lefez, B; Beucher, E

2004-02-01

This study shows the effects of roughness on infrared spectra shapes of thin corrosion products on metallic substrates. The calculated spectra show that the baseline is mainly affected by increasing roughness and that such effects do not shift the position of the absorption bands. The model obtained has been used to extract data of artificial patina on a copper surface. Surface defects of copper substrates can be distinguished on the whole surface, from the morphological and chemical points of view, using optical profilometry and infrared microspectroscopy. An homogeneous layer of cuprite covers the surface except in the linear defects. Fourier transform infrared (FT-IR) analysis indicates that a mixture of atacamite and clinoatacamite is mainly located in these scratches. The width of these particular areas is in good agreement with profilometric observations.

Crystal truncation rods from miscut surfaces

DOE PAGES

Petach, Trevor A.; Mehta, Apurva; Toney, Michael F.; ...

2017-05-08

Crystal truncation rods are used to study surface and interface structure. Since real surfaces are always somewhat miscut from a low index plane, it is important to study the effect of miscuts on crystal truncation rods. We develop a model that describes the truncation rod scattering from miscut surfaces that have steps and terraces. We show that nonuniform terrace widths and jagged step edges are both forms of roughness that decrease the intensity of the rods. Nonuniform terrace widths also result in a broad peak that overlaps the rods. We use our model to characterize the terrace width distribution andmore » step edge jaggedness on three SrTiO 3 (001) samples, showing excellent agreement between the model and the data, confirmed by atomic force micrographs of the surface morphology. As a result, we expect our description of terrace roughness will apply to many surfaces, even those without obvious terracing.« less

Lateral ventricle morphology analysis via mean latitude axis.

PubMed

Paniagua, Beatriz; Lyall, Amanda; Berger, Jean-Baptiste; Vachet, Clement; Hamer, Robert M; Woolson, Sandra; Lin, Weili; Gilmore, John; Styner, Martin

2013-03-29

Statistical shape analysis has emerged as an insightful method for evaluating brain structures in neuroimaging studies, however most shape frameworks are surface based and thus directly depend on the quality of surface alignment. In contrast, medial descriptions employ thickness information as alignment-independent shape metric. We propose a joint framework that computes local medial thickness information via a mean latitude axis from the well-known spherical harmonic (SPHARM-PDM) shape framework. In this work, we applied SPHARM derived medial representations to the morphological analysis of lateral ventricles in neonates. Mild ventriculomegaly (MVM) subjects are compared to healthy controls to highlight the potential of the methodology. Lateral ventricles were obtained from MRI scans of neonates (9-144 days of age) from 30 MVM subjects as well as age- and sex-matched normal controls (60 total). SPHARM-PDM shape analysis was extended to compute a mean latitude axis directly from the spherical parameterization. Local thickness and area was straightforwardly determined. MVM and healthy controls were compared using local MANOVA and compared with the traditional SPHARM-PDM analysis. Both surface and mean latitude axis findings differentiate successfully MVM and healthy lateral ventricle morphology. Lateral ventricles in MVM neonates show enlarged shapes in tail and head. Mean latitude axis is able to find significant differences all along the lateral ventricle shape, demonstrating that local thickness analysis provides significant insight over traditional SPHARM-PDM. This study is the first to precisely quantify 3D lateral ventricle morphology in MVM neonates using shape analysis.

Tailoring the morphology of raspberry-like carbon black/polystyrene composite microspheres for fabricating superhydrophobic surface

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

Bao, Yubin; Li, Qiuying, E-mail: liqy@ecust.edu.cn; Shanghai Key Laboratory Polymeric Materials

In our previous report, raspberry-like carbon black/polystyrene (CB/PS) composite microsphere was prepared through heterocoagulation process. Based on the previous study, in the present work, the morphology of raspberry-like CB/PS particle is tailored through adjusting the polarity and the concentration ratio of CB/PS colloidal suspension with the purpose to prepare particulate film for the fabrication of superhydrophobic surface. Scanning electron microscope (SEM) confirms the morphology of raspberry-like particle and the coverage of CB. Rough surfaces fabricated by raspberry-like particles with proper morphology are observed by SEM and clear evidence of superhydrophobic surface is shown. The structure of raspberry-like particle is analyzedmore » by atom force microscope. The proposed relationship between the hydrophobicity and the structure of CB aggregates on the surface of PS microsphere is discussed in details.« less

Simulating galaxies in the reionization era with FIRE-2: morphologies and sizes

NASA Astrophysics Data System (ADS)

Ma, Xiangcheng; Hopkins, Philip F.; Boylan-Kolchin, Michael; Faucher-Giguère, Claude-André; Quataert, Eliot; Feldmann, Robert; Garrison-Kimmel, Shea; Hayward, Christopher C.; Kereš, Dušan; Wetzel, Andrew

2018-06-01

We study the morphologies and sizes of galaxies at z ≥ 5 using high-resolution cosmological zoom-in simulations from the Feedback In Realistic Environments project. The galaxies show a variety of morphologies, from compact to clumpy to irregular. The simulated galaxies have more extended morphologies and larger sizes when measured using rest-frame optical B-band light than rest-frame UV light; sizes measured from stellar mass surface density are even larger. The UV morphologies are usually dominated by several small, bright young stellar clumps that are not always associated with significant stellar mass. The B-band light traces stellar mass better than the UV, but it can also be biased by the bright clumps. At all redshifts, galaxy size correlates with stellar mass/luminosity with large scatter. The half-light radii range from 0.01 to 0.2 arcsec (0.05-1 kpc physical) at fixed magnitude. At z ≥ 5, the size of galaxies at fixed stellar mass/luminosity evolves as (1 + z)-m, with m ˜ 1-2. For galaxies less massive than M* ˜ 108 M⊙, the ratio of the half-mass radius to the halo virial radius is ˜ 10 per cent and does not evolve significantly at z = 5-10; this ratio is typically 1-5 per cent for more massive galaxies. A galaxy's `observed' size decreases dramatically at shallower surface brightness limits. This effect may account for the extremely small sizes of z ≥ 5 galaxies measured in the Hubble Frontier Fields. We provide predictions for the cumulative light distribution as a function of surface brightness for typical galaxies at z = 6.

Behavior of osteoblast-like cells on calcium-deficient hydroxyapatite ceramics composed of particles with different shapes and sizes.

PubMed

Kamitakahara, Masanobu; Uno, Yuika; Ioku, Koji

2014-01-01

In designing the biomaterials, it is important to control their surface morphologies, because they affect the interactions between the materials and cells. We previously reported that porous calcium-deficient hydroxyapatite (HA) ceramics composed of rod-like particles had advantages over sintered porous HA ceramics; however, the effects of the surface morphology of calcium-deficient HA ceramics on cell behavior have remained unclear. Using a hydrothermal process, we successfully prepared porous calcium-deficient HA ceramics with different surface morphologies, composed of plate-like particles of 200-300, 500-800 nm, or 2-3 μm in width and rod-like particles of 1 or 3-5 μm in width, respectively. The effects of these surface morphologies on the behavior of osteoblast-like cells were examined. Although the numbers of cells adhered to the ceramic specimens did not differ significantly among the specimens, the proliferation rates of cells on the ceramics decreased with decreasing particle size. Our results reveal that controlling the surface morphology that is governed by particle shape and size is important for designing porous calcium-deficient HA ceramics.

Morphology control of zinc regeneration for zinc-air fuel cell and battery

NASA Astrophysics Data System (ADS)

Wang, Keliang; Pei, Pucheng; Ma, Ze; Xu, Huachi; Li, Pengcheng; Wang, Xizhong

2014-12-01

Morphology control is crucial both for zinc-air batteries and for zinc-air fuel cells during zinc regeneration. Zinc dendrite should be avoided in zinc-air batteries and zinc pellets are yearned to be formed for zinc-air fuel cells. This paper is mainly to analyze the mechanism of shape change and to control the zinc morphology during charge. A numerical three-dimensional model for zinc regeneration is established with COMSOL software on the basis of ionic transport theory and electrode reaction electrochemistry, and some experiments of zinc regeneration are carried out. The deposition process is qualitatively analyzed by the kinetics Monte Carlo method to study the morphological change from the electrocrystallization point of view. Morphological evolution of deposited zinc under different conditions of direct currents and pulse currents is also investigated by simulation. The simulation shows that parametric variables of the flowing electrolyte, the surface roughness and the structure of the electrode, the charging current and mode affect morphological evolution. The uniform morphology of deposited zinc is attained at low current, pulsating current or hydrodynamic electrolyte, and granular morphology is obtained by means of an electrode of discrete columnar structure in combination with high current and flowing electrolyte.

Regulation the morphology of cationized gold nanoparticles for effective gene delivery.

PubMed

Zhang, Peng; Li, Bangbang; Du, Jianwei; Wang, Youxiang

2017-09-01

Recent research indicated that the morphology of nanoparticles could result in distinct biological behaviors, thus played an important role in designing efficient gene delivery systems. Among them, gold nanoparticles (AuNPs) with various shapes were widely studied due to the good biocompatibility and easy modification ability. Our recent research indicated that polyethyleneimine-g-bovine serum albumin (BSA-PEI) as non-viral gene vector showed good colloid stability and high transfection efficiency. In this work, BSA-PEI was utilized to modify gold nanospheres (AuNSs) and gold nanorods (AuNRs) to investigate the influence of the morphology on gene delivery. Both AuNS@BSA-PEI and AuNR@BSA-PEI nanoparticles condensed DNA effectively at N/P ratio above 5 and maintained spherical or rod-like morphology respectively. Due to the higher surface charge density at the tips, the rod-like gene complexes were prone to use the tips to contact with cell membrane, which facilitated to be uptaked by HepG2 cells. The endocytosis inhibition experiments showed some differences in the endocytic pathway. Gene transfection experiment showed that the rod-like complexes had almost 100-fold higher of transfection level than that of spherical complexes at the N/P ratio of 20. This work provided a potential strategy for further design of gene vectors with improved transfection results by adjusting the morphology of gene vectors. Copyright © 2017. Published by Elsevier B.V.

Morphology and antimony segregation of spangles on batch hot-dip galvanized coatings

NASA Astrophysics Data System (ADS)

Peng, Shu; Lu, Jintang; Che, Chunshan; Kong, Gang; Xu, Qiaoyu

2010-06-01

Spangles produced by batch hot-dip galvanizing process have a rougher surface and a greater surface segregation of alloying element compared with those in continuous hot-dip galvanizing line (CGL), owing to the cooling rate of the former is much smaller than that of the later. Therefore, typical spangles on a batch hot-dipped Zn-0.05Al-0.2Sb alloy coating were investigated. The chemical, morphological characterization and identification of the phases on the spangles were examined by scanning electron microscopy (SEM), backscattered electron imaging (BSE), atomic force microscopy (AFM), energy dispersive spectroscopy (EDS) and X-ray diffraction analysis (XRD). The results showed that the coating surface usually exhibited three kinds of spangles: shiny, feathery and dull spangle, of which extensively antimony surface segregation was detected. The nature of precipitate on the coating surface was identified as β-Sb 3Zn 4, The precipitated β-Sb 3Zn 4 particles distributed randomly on the shiny spangle surface, both β-Sb 3Zn 4 particles and dentritic segregation of antimony dispersed in the dendritic secondary arm spacings of the feathery spangle and on the whole dull spangle surface. The dentritic segregation of antimony and precipitation of Sb 3Zn 4 compound are discussed by a proposed model.

Facile electrocatalytic redox of hemoglobin by flower-like gold nanoparticles on boron-doped diamond surface.

PubMed

Li, Mingfang; Zhao, Guohua; Geng, Rong; Hu, Huikang

2008-11-01

The flower-like gold nanoparticles together with spherical and convex polyhedron gold nanoparticles were fabricated on boron-doped diamond (BDD) surface by one-step and simple electrochemical method through easily controlling the applied potential and the concentration of HAuCl(4). The recorded X-ray diffraction (XRD) patterns confirmed that these three shapes of gold nanoparticles were dominated by different crystal facets. The cyclic voltammetric results indicated that the morphology of gold nanoparticles plays big role in their electrochemical behaviors. The direct electrochemistry of hemoglobin (Hb) was realized on all the three different shapes of nanogold-attached BDD surface without the aid of any electron mediator. In pH 4.5 acetate buffer solutions (ABS), Hb showed a pair of well defined and quasi-reversible redox peaks. However, the results obtained demonstrated that the redox peak potential, the average surface concentration of electroactive heme, and the electron transfer rates of Hb are greatly dependent upon the surface morphology of gold nanoparticles. The electron transfer rate constant of hemoglobin over flower-like nanogold/BDD electrode was more than two times higher than that over spherical and convex polyhedron nanogold. The observed differences may be ascribed to the difference in gold particle characteristics including surface roughness, exposed surface area, and crystal structure.

Solid-State Synthesized Nanostructured Au Dendritic Aggregates Towards Surface-Enhanced Raman Spectroscopy

NASA Astrophysics Data System (ADS)

Gentile, A.; Ruffino, F.; D'Andrea, C.; Gucciardi, P. G.; Reitano, R.; Grimaldi, M. G.

2016-06-01

Micrometric Au structures, presenting a dendritic nano-structure, have been fabricated on a Si-based substrate. The fabrication method involves the deposition of a thin Au film on the substrate and a high-temperature annealing (1100°C) using fast heating and cooling ramps. The thermal process produces the growth, from the substrate, of Si micro-pillars whose top surfaces, covered by a crystalline Au layer, present a nanodendritic morphology. In addition to the micro-pillars, the sample surface presents a complex structural and chemical composition including Si3N4 regions due to the silicon-nitrogen intermixing during the heating stage. By studying the kinetic processes at the Au-Si interface during the thermal treatment, we describe the stages involved in the micro-pillars growth, in the dendritic morphology development, and in the Au atoms entrapment at the top of the dendritic surfaces. Finally, we present the analyses of the optical and surface enhanced Raman scattering properties of the Au dendritic aggregates. We show, in particular, that: (1) the Au dendrites aggregates act as effective scattering elements for the electromagnetic radiation in the infrared spectral region; and (2) the higher surface area due to the branched dendritic structure is responsible for the improvement in the sensitivity of the surface enhanced Raman scattering activity.

Visualizing Morphological Changes of Abscission Zone Cells in Arabidopsis by Scanning Electron Microscope.

PubMed

Shi, Chun-Lin; Butenko, Melinka A

2018-01-01

Scanning electron microscope (SEM) is a type of electron microscope which produces detailed images of surface structures. It has been widely used in plants and animals to study cellular structures. Here, we describe a detailed protocol to prepare samples of floral abscission zones (AZs) for SEM, as well as further image analysis. We show that it is a powerful tool to detect morphologic changes at the cellular level during the course of abscission in wild-type plants and to establish the details of phenotypic alteration in abscission mutants.

Utilizing dynamic laser speckle to probe nanoscale morphology evolution in nanoporous gold thin films

DOE PAGES

Chapman, Christopher A. R.; Ly, Sonny; Wang, Ling; ...

2016-03-02

Here we show the use of dynamic laser speckle autocorrelation spectroscopy in conjunction with the photothermal treatment of nanoporous gold (np-Au) thin films to probe nanoscale morphology changes during the photothermal treatment. Utilizing this spectroscopy method, backscattered speckle from the incident laser is tracked during photothermal treatment and both the characteristic feature size and annealing time of the film are determined. These results demonstrate that this method can successfully be used to monitor laser-based surface modification processes without the use of ex-situ characterization.

Competitive Adsorption-Assisted Formation of One-Dimensional Cobalt Nanochains with High CO Hydrogenation Activity

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

Liang, Xin; Ren, Zhibo; Zhu, Xiaolin

In the present work, cobalt nanochains have been successfully synthesized by a novel co assisted self-assembling formation strategy. A dramatic morphology transformation from cobalt nanoparticles to nanochains are observed when co molecules were introduced into the synthetic system. DFT calculations further confirm that competitive co-adsorbed co and oleylamine over the cobalt nanoparticles facilitates the formation of cobalt nanochains, which show higher co hydrogenation performance. The present work provides a new strategic and promising method for controllable synthesis of catalyst nanomaterials with the preferred surface structure and morphology.

Utilizing dynamic laser speckle to probe nanoscale morphology evolution in nanoporous gold thin films

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

Chapman, Christopher A. R.; Ly, Sonny; Wang, Ling

Here we show the use of dynamic laser speckle autocorrelation spectroscopy in conjunction with the photothermal treatment of nanoporous gold (np-Au) thin films to probe nanoscale morphology changes during the photothermal treatment. Utilizing this spectroscopy method, backscattered speckle from the incident laser is tracked during photothermal treatment and both the characteristic feature size and annealing time of the film are determined. These results demonstrate that this method can successfully be used to monitor laser-based surface modification processes without the use of ex-situ characterization.

Front Instabilities and Invasiveness of Simulated Avascular Tumors

PubMed Central

Popławski, Nikodem J.; Agero, Ubirajara; Gens, J. Scott; Swat, Maciej; Glazier, James A.; Anderson, Alexander R. A.

2009-01-01

We study the interface morphology of a 2D simulation of an avascular tumor composed of identical cells growing in an homogeneous healthy tissue matrix (TM), in order to understand the origin of the morphological changes often observed during real tumor growth. We use the GlazierGraner-Hogeweg model, which treats tumor cells as extended, deformable objects, to study the effects of two parameters: a dimensionless diffusion-limitation parameter defined as the ratio of the tumor consumption rate to the substrate transport rate, and the tumor-TM surface tension. We model TM as a nondiffusing field, neglecting the TM pressure and haptotactic repulsion acting on a real growing tumor; thus our model is appropriate for studying tumors with highly motile cells, e.g., gliomas. We show that the diffusion-limitation parameter determines whether the growing tumor develops a smooth (noninvasive) or fingered (invasive) interface, and that the sensitivity of tumor morphology to tumor-TM surface tension increases with the size of the dimensionless diffusion-limitation parameter. For large diffusion-limitation parameters we find a transition (missed in previous work) between dendritic structures, produced when tumor-TM surface tension is high, and seaweed-like structures, produced when tumor-TM surface tension is low. This observation leads to a direct analogy between the mathematics and dynamics of tumors and those observed in nonbiological directional solidification. Our results are also consistent with biological observation that hypoxia promotes invasive growth of tumor cells by inducing higher levels of receptors for scatter factors that weaken cell-cell adhesion and increase cell motility. These findings suggest that tumor morphology may have value in predicting the efficiency of antiangiogenic therapy in individual patients. PMID:19234746

The role of support morphology on the performance of Cu/ZnO-catalyst for hydrogenation of CO{sub 2} to methanol

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

Tasfy, Sara Faiz Hanna, E-mail: miss25208@gmail.com; Zabidi, Noor Asmawati Mohd, E-mail: noorasmawati-mzabidi@petronas.com.my; Shaharun, Maizatul Shima, E-mail: maizats@petronas.com.my

The effects of SBA-15 support morphology on the activity of Cu/ZnO catalyst in the hydrogenation of CO{sub 2} to methanol was investigated. In the hydrogenation of CO{sub 2} to methanol at 210°C, 2.25 MPa, H{sub 2}/CO{sub 2} ratio of three remarkable difference was obtained using Cu/ZnO catalyst supported on SBA-15 with different morphology. The catalysts were characterized using N{sub 2}-adsorption, field emission scanning microscopy (FESEM/EDX), transmission electron microscopy (HRTEM), and temperature-programmed reduction (TPR). Characterization of the catalyst showed that support morphology, surface area, metals dispersion, and reducibility influenced the catalytic performance. On the fiber-shaped SBA-15, copper dispersion was 29 % whereasmore » on the spherical-shaped SBA-15, the dispersion was 20 %. The experimental results showed that the catalyst supported over fiber-shaped SBA-15 exhibit higher CO{sub 2} conversion (13.96 %) and methanol selectivity (91.32 %) compare to catalyst supported over spherical-shaped SBA-15.« less

Improved morphology for ohmic contacts to AlGaN/GaN high electron mobility transistors using WSix- or W-based metallization

NASA Astrophysics Data System (ADS)

Luo, B.; Ren, F.; Fitch, R. C.; Gillespie, J. K.; Jenkins, T.; Sewell, J.; Via, D.; Crespo, A.; Baca, A. G.; Briggs, R. D.; Gotthold, D.; Birkhahn, R.; Peres, B.; Pearton, S. J.

2003-06-01

A comparison was made of specific contact resistivity and morphology of Ti/Al/Pt/WSi/Ti/Au and Ti/Al/Pt/W/Ti/Au ohmic contacts to AlGaN/GaN heterostructures relative to the standard Ti/Al/Pt/Au metallization. The W- and WSi-based contacts show comparable specific resistivities to that of the standard contact on similar layer structures, reaching minimum values of ˜10-5 Ω cm2 after annealing in the range 850-900 °C. However, the W- and WSi-based contacts exhibit much smoother surface morphologies, even after 950 °C annealing. For example, the root-mean-square roughness of the Ti/Al/Pt/WSi/Ti/Au contact annealed at 950 °C was unchanged from the as-deposited values whereas the Ti/Al/Pt/Au contact shows significant deterioration of the morphology under these conditions. The improved thermal stability of the W- and WSix-based contacts is important for maintaining edge acuity during high-temperature operation.

Etude hydromecanique d'une fracture en cisaillement sous contrainte normale constante

NASA Astrophysics Data System (ADS)

Lamontagne, Eric

This research study deals with the effects of shear direction and injection flow rate on the flow directional anisotropy for a given normal stress. It presents experimental works on hydromechanical shear behaviour of a fracture under constant normal stress conditions that permits the characterisation of the intrinsic hydraulic transmissivity in relation with the directional anisotropy of the roughness morphology on the fracture surfaces. Tests were performed on mortar replicas of a natural fracture so that the fracture roughness and void space geometry were kept the same for each test. The experimental work program was performed through direct shear tests on the fracture replicas in four shear directions under four constant normal stress levels. The application of the normal stress was followed by several injections of fluid under constant flow rate. Then, for each defined shear displacement, several injections of fluid were done at different flow rate but under constant flow rate. The test results show that: (1) for the whole shear tests, the global intrinsic transmissivity is included within an enveloping zone of about one order of size. The transmissivity curves within the enveloping zone has a particularity to increase about two orders of size in the first millimetre of shear displacement and subsequently stabilised rapidly; (2) the highest dilatancy do not correspond necessarily with the highest intrinsic transmissivity so that, the behaviour of the global intrinsic transmissivity is not directly proportional to the fracture dilatancy during shear; (3) after the peak shear stress, the divergence is more marked between the global intrinsic transmissivity curves at various flow rate; (4) after peak shear strength and the beginning of asperity degradation, the gradual passage to residual friction shear behaviour causes a directional flow anisotropy and a reorientation of the flow chenalisation direction sub perpendicularly to the shear direction; (5) the anisotropy is not to develop equally between the two sense in the perpendicular direction to shear direction. In order to characterise the dynamics of the flow pattern in the fracture, a statistical analysis of the surfaces morphology of the fracture and the casting of void space geometry were performed before and after shear. A statistical analysis of asperity heights, on the global scale of the fracture surfaces, permits to characterise the fracture morphology and put in evidence a large morphological structure on which are superposed smaller asperities of variable dimensions. This large dimension structure generate a higher level landing occupying more than half of the fracture area. The study of the surfaces morphology of the fracture, performed with the geostatistical mean asperity heights variogram by direction before shearing, show the presence of two entangled morphologic structure families (28 and 15 mm). This same study done after shearing shows that the asperity degradation seems associated with the reduction of the global intrinsic transmissivity of the fracture. Finally, the void spaces morphology evaluated by casting techniques, during the shear tests, has permitted to verify the contacts evolution with the increasing shear displacement and visualised flow chenalisation during fracture shearing.

Cell morphology, viability, osteocalcin activity, and alkaline phosphatase activity in milled versus unmilled surface of the femoral head.

PubMed

Rhyu, Kee Hyung; Cho, Chang Hoon; Yoon, Kyung Sik; Chun, Young Soo

2016-12-01

To evaluate cellular activity in milled versus unmilled surface of the femoral head in 21 patients who underwent robot-assisted total hip arthroplasty(THA). The femoral head of 21 consecutive patients who underwent robot-assisted THA for osteonecrosis was used. 10 cc of trabecular bone from the entire milled surface was obtained using a curette. The same amount of trabecular bone was obtained at least 1 cm away from the milled surface and served as a matched control. Cell morphology, viability, osteocalcin activity, and alkaline phosphatase activity in milled versus unmilled surface were assessed. Cell morphology of the milled or unmilled surface was comparable; cells were smaller in the milled surface. Cell viability was a mean of 40% higher in the milled surface (107.4% vs. 67.2%, p<0.001); cell viability at 5 time points was comparable in each group. Osteocalcin activity of cells was slightly higher in the milled surface (1.43 vs. 1.24 ng/ml, p=0.69). Alkaline phosphatase activity of cells was slightly higher in the unmilled surface (150 105 vs. 141 789 U/L, p=0.078). The milled and unmilled surfaces of the femoral head were comparable in terms of cell morphology, viability, osteocalcin activity, and alkaline phosphatase activity.

Nanoimprinted ultrafine line and space nanogratings for liquid crystal alignment.

PubMed

Liu, Yan Jun; Loh, Wei Wei; Leong, Eunice Sok Ping; Kustandi, Tanu Suryadi; Sun, Xiao Wei; Teng, Jing Hua

2012-11-23

Ultrafine 50 nm line and space nanogratings were fabricated using nanoimprint lithography, and were further used as an alignment layer for liquid crystals. The surface morphologies of the nanogratings were characterized and their surface energies were estimated through the measurement of the contact angles for two different liquids. Experimental results show that the surface energies of the nanogratings are anisotropic: the surface free energy towards the direction parallel to the grating lines is higher than that in the direction perpendicular to the grating lines. Electro-optical characteristics were tested from a twisted nematic liquid crystal cell, which was assembled using two identical nanogratings. Experimental results show that such a kind of nanograting is promising as an alternative to the conventional rubbing process for liquid crystal alignment.

Effect of surface topological structure and chemical modification of flame sprayed aluminum coatings on the colonization of Cylindrotheca closterium on their surfaces

NASA Astrophysics Data System (ADS)

Chen, Xiuyong; He, Xiaoyan; Suo, Xinkun; Huang, Jing; Gong, Yongfeng; Liu, Yi; Li, Hua

2016-12-01

Biofouling is one of the major problems for the coatings used for protecting marine infrastructures during their long-term services. Regulation in surface structure and local chemistry is usually the key for adjusting antifouling performances of the coatings. In this study, flame sprayed multi-layered aluminum coatings with micropatterned surfaces were constructed and the effects of their surface structure and chemistry on the settlement of typical marine diatoms were investigated. Micropatterned topographical morphology of the coatings was constructed by employing steel mesh as a shielding plate during the coating deposition. A silicone elastomer layer for sealing and interconnection was further brush-coated on the micropatterned coatings. Additional surface modification was made using zwitterionic molecules via DOPA linkage. The surface-modified coatings resist effectively colonization of Cylindrotheca closterium. This is explained by the quantitative examination of a simplified conditioning layer that deteriorated adsorption of bovine calf serum proteins on the zwitterionic molecule-treated samples is revealed. The colonization behaviors of the marine diatoms are markedly influenced by the micropatterned topographical morphology. Either the surface micropatterning or the surface modification by zwitterionic molecules enhances antimicrobial ability of the coatings. However, the combined micropatterned structure and zwitterionic modification do not show synergistic effect. The results give insight into anti-corrosion/fouling applications of the modified aluminum coatings in the marine environment.

The effects of solidification on sill propagation dynamics and morphology

NASA Astrophysics Data System (ADS)

Chanceaux, L.; Menand, T.

2016-05-01

Sills are an integral part of the formation and development of larger plutons and magma reservoirs. Thus sills are essential for both the transport and the storage of magma in the Earth's crust. However, although cooling and solidification are central to magmatism, their effects on sills have been so far poorly studied. Here, the effects of solidification on sill propagation dynamics and morphology are studied by means of analogue laboratory experiments. Hot fluid vegetable oil (magma analogue), that solidifies during its propagation, is injected as a sill in a colder layered gelatine solid (elastic host rock analogue). The injection flux and temperature are maintained constant during an experiment and systematically varied between each experiment, in order to vary and quantify the amount of solidification between each experiments. The oil is injected directly at the interface between the two gelatine layers. When solidification effects are small (high injection temperatures and fluxes), the propagation is continuous and the sill has a regular and smooth surface. Inversely, when solidification effects are important (low injection temperatures and fluxes), sill propagation is discontinuous and occurs by steps of surface-area creation interspersed with periods of momentary arrest. The morphology of these sills displays folds, ropy structures on their surface, and lobes with imprints of the leading fronts that correspond to each step of area creation. These experiments show that for a given, constant injected volume, as solidification effects increase, the area of the sills decreases, their thickness increases, and the number of propagation steps increases. These results have various geological and geophysical implications. The morphology of sills, such as lobate structures (interpretation of 3D seismic studies in sedimentary basin) and ropy flow structures (field observations) can be related to solidification during emplacement. Moreover, a non-continuous morphology as observed in the field does not necessarily involve multiple injections, but could instead reflect a continuous, yet complex morphology induced by solidification effects during emplacement. Also, a discontinuous sill propagation induced by solidification effects should be associated with bursts of seismic activity. Finally, our study shows that once a sill has initiated, the dimensionless flux influences the sill thermal state, and in turn its propagation, and final extent and thickness. In restricting the lateral extent of sills, magma cooling and solidification are likely to impact directly the size of plutons constructed by amalgamated sills.

Effect of polymer coating on the osseointegration of CP-Ti dental implant

NASA Astrophysics Data System (ADS)

Al-Hassani, Emad; Al-Hassani, Fatima; Najim, Manar

2018-05-01

Modifications achieved coatings of titanium samples were investigated in order to improve their surface characteristics so as to facilitate bio-integration. Chitosan coating was use for commercial pure Ti alloys manufactured by two different methods in which commercial pure titanium rod converted in form of implant screw by using wire cut machine and lathe, second method included the used of powder technology for producing the implant screws. The coating process of chitosan polymer was carried out using advance technology (electrospnning process) to create fibrous structure from Nano to micro scale of the chitosan on the implant surface which result in a bioactive surface. The characterization includes; microstructure observation, surface chemical composition analysis (EDS), surface roughness (AFM), and the histological analysis. from the SEM No morphological differences were observed among the implants surfaces except for some inconsiderable morphological differences that results from the manufacturing process, by using EDX analysis the surfaces chemical compositions were completely changed and there was large decrease in the percentage of titanium element at the surface which indicates that the surface is covered with chitosan and had a new surface composition and topography. The sample was produced by powder technology process have higher roughness (845.36 nm) than sample produced by machining without any surface treatment (531.7nm),finally The histological view of implant samples after 4weeks of implantation, showed active bone formation in all implant surface which give clear indication of tissue acceptance.

Understanding the Growth Mechanism of GaN Epitaxial Layers on Mechanically Exfoliated Graphite

NASA Astrophysics Data System (ADS)

Li, Tianbao; Liu, Chenyang; Zhang, Zhe; Yu, Bin; Dong, Hailiang; Jia, Wei; Jia, Zhigang; Yu, Chunyan; Gan, Lin; Xu, Bingshe; Jiang, Haiwei

2018-04-01

The growth mechanism of GaN epitaxial layers on mechanically exfoliated graphite is explained in detail based on classic nucleation theory. The number of defects on the graphite surface can be increased via O-plasma treatment, leading to increased nucleation density on the graphite surface. The addition of elemental Al can effectively improve the nucleation rate, which can promote the formation of dense nucleation layers and the lateral growth of GaN epitaxial layers. The surface morphologies of the nucleation layers, annealed layers and epitaxial layers were characterized by field-emission scanning electron microscopy, where the evolution of the surface morphology coincided with a 3D-to-2D growth mechanism. High-resolution transmission electron microscopy was used to characterize the microstructure of GaN. Fast Fourier transform diffraction patterns showed that cubic phase (zinc-blend structure) GaN grains were obtained using conventional GaN nucleation layers, while the hexagonal phase (wurtzite structure) GaN films were formed using AlGaN nucleation layers. Our work opens new avenues for using highly oriented pyrolytic graphite as a substrate to fabricate transferable optoelectronic devices.

Uniformity studies of inductively coupled plasma etching in fabrication of HgCdTe detector arrays

NASA Astrophysics Data System (ADS)

Bommena, R.; Velicu, S.; Boieriu, P.; Lee, T. S.; Grein, C. H.; Tedjojuwono, K. K.

2007-04-01

Inductively coupled plasma (ICP) chemistry based on a mixture of CH 4, Ar, and H II was investigated for the purpose of delineating HgCdTe mesa structures and vias typically used in the fabrication of second and third generation infrared photo detector arrays. We report on ICP etching uniformity results and correlate them with plasma controlling parameters (gas flow rates, total chamber pressure, ICP power and RF power). The etching rate and surface morphology of In-doped MWIR and LWIR HgCdTe showed distinct dependences on the plasma chemistry, total pressure and RF power. Contact stylus profilometry and cross-section scanning electron microscopy (SEM) were used to characterize the anisotropy of the etched profiles obtained after various processes and a standard deviation of 0.06 μm was obtained for etch depth on 128 x 128 format array vias. The surface morphology and the uniformity of the etched surfaces were studied by plan view SEM. Atomic force microscopy was used to make precise assessments of surface roughness.

Understanding the Growth Mechanism of GaN Epitaxial Layers on Mechanically Exfoliated Graphite.

PubMed

Li, Tianbao; Liu, Chenyang; Zhang, Zhe; Yu, Bin; Dong, Hailiang; Jia, Wei; Jia, Zhigang; Yu, Chunyan; Gan, Lin; Xu, Bingshe; Jiang, Haiwei

2018-04-27

The growth mechanism of GaN epitaxial layers on mechanically exfoliated graphite is explained in detail based on classic nucleation theory. The number of defects on the graphite surface can be increased via O-plasma treatment, leading to increased nucleation density on the graphite surface. The addition of elemental Al can effectively improve the nucleation rate, which can promote the formation of dense nucleation layers and the lateral growth of GaN epitaxial layers. The surface morphologies of the nucleation layers, annealed layers and epitaxial layers were characterized by field-emission scanning electron microscopy, where the evolution of the surface morphology coincided with a 3D-to-2D growth mechanism. High-resolution transmission electron microscopy was used to characterize the microstructure of GaN. Fast Fourier transform diffraction patterns showed that cubic phase (zinc-blend structure) GaN grains were obtained using conventional GaN nucleation layers, while the hexagonal phase (wurtzite structure) GaN films were formed using AlGaN nucleation layers. Our work opens new avenues for using highly oriented pyrolytic graphite as a substrate to fabricate transferable optoelectronic devices.

Engineering plasmonic nanostructured surfaces by pulsed laser deposition

NASA Astrophysics Data System (ADS)

Ghidelli, Matteo; Mascaretti, Luca; Bricchi, Beatrice Roberta; Zapelli, Andrea; Russo, Valeria; Casari, Carlo Spartaco; Li Bassi, Andrea

2018-03-01

The synthesis and the optical response of gold nanoparticles (NPs) and thin nanostructured films grown by pulsed laser deposition (PLD) are here studied. Different PLD process parameters - including background gas pressure and the number of laser shots as well as post-deposition annealing treatments - have been varied to control the growth of Au NPs and films, thus tuning the surface plasmon characteristics. The mechanisms of NPs and film growth have been explored performing a morphological characterization by Scanning Electron Microscopy (SEM) and Atomic Force Microscopy (AFM), and the correlation with the optical behavior is investigated. We show that the size distribution and the morphology of the as deposited Au NPs depend on growth mechanisms which are controlled by tuning the deposition process, while the optical behavior is strongly affected by the average size and surface density of NPs or by the length of percolated Au domains. Furthermore, nucleation in gas phase has been reported at high (1000 Pa Ar) background pressures, enabling independent control of NP size and coverage, contrary to surface driven NP growth by diffusion and aggregation on substrate.

Probing the Role of Zr Addition versus Textural Properties in Enhancement of CO 2 Adsorption Performance in Silica/PEI Composite Sorbents

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

Sakwa-Novak, Miles A.; Holewinski, Adam; Hoyt, Caroline B.

2015-08-08

Polymeric amines such as poly(ethylenimine) (PEI) supported on mesoporous oxides are promising candidate adsorbents for CO 2 capture processes. One important aspect to the design and optimization of these materials is a fundamental understanding of how the properties of the oxide support such as pore structure, particle morphology, and surface properties affect the efficiency of the guest polymer in its interactions with CO 2. Previously, the efficiency of impregnated PEI to adsorb CO 2 was shown to increase upon the addition of Zr as a surface modifier in SBA-15. But, the efficacy of this method to tune the adsorption performancemore » has not been explored in materials of differing textural and morphological nature. These issues are directly addressed via the preparation of an array of SBA-15 support materials with varying textural and morphological properties, as well as varying content of zirconium doped into the material. Zirconium is incorporated into the SBA-15 either during the synthesis of the SBA-15, or postsynthetically via deposition of Zr species onto pure-silica SBA-15. The method of Zr incorporation alters the textural and morphological properties of the parent SBA-15 in different ways. Importantly, the CO 2 capacity of SBA-15 impregnated with PEI increases by a maximum of ~60% with the quantity of doped Zr for a “standard” SBA-15 containing significant microporosity, while no increase in the CO 2 capacity is observed upon Zr incorporation for an SBA-15 with reduced microporosity and a larger pore size, pore volume, and particle size. Finally, adsorbents supported on SBA-15 with controlled particle morphology show only modest increases in CO 2 capacity upon inclusion of Zr to the silica framework. The data demonstrate that the textural and morphological properties of the support have a more significant impact on the ability of PEI to capture CO 2 than the support surface composition.« less

Probing the Role of Zr Addition versus Textural Properties in Enhancement of CO₂ Adsorption Performance in Silica/PEI Composite Sorbents.

PubMed

Sakwa-Novak, Miles A; Holewinski, Adam; Hoyt, Caroline B; Yoo, Chun-Jae; Chai, Song-Hai; Dai, Sheng; Jones, Christopher W

2015-09-01

Polymeric amines such as poly(ethylenimine) (PEI) supported on mesoporous oxides are promising candidate adsorbents for CO2 capture processes. An important aspect to the design and optimization of these materials is a fundamental understanding of how the properties of the oxide support such as pore structure, particle morphology, and surface properties affect the efficiency of the guest polymer in its interactions with CO2. Previously, the efficiency of impregnated PEI to adsorb CO2 was shown to increase upon the addition of Zr as a surface modifier in SBA-15. However, the efficacy of this method to tune the adsorption performance has not been explored in materials of differing textural and morphological nature. Here, these issues are directly addressed via the preparation of an array of SBA-15 support materials with varying textural and morphological properties, as well as varying content of zirconium doped into the material. Zirconium is incorporated into the SBA-15 either during the synthesis of the SBA-15, or postsynthetically via deposition of Zr species onto pure-silica SBA-15. The method of Zr incorporation alters the textural and morphological properties of the parent SBA-15 in different ways. Importantly, the CO2 capacity of SBA-15 impregnated with PEI increases by a maximum of ∼60% with the quantity of doped Zr for a "standard" SBA-15 containing significant microporosity, while no increase in the CO2 capacity is observed upon Zr incorporation for an SBA-15 with reduced microporosity and a larger pore size, pore volume, and particle size. Finally, adsorbents supported on SBA-15 with controlled particle morphology show only modest increases in CO2 capacity upon inclusion of Zr to the silica framework. The data demonstrate that the textural and morphological properties of the support have a more significant impact on the ability of PEI to capture CO2 than the support surface composition.

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

Sakwa-Novak, Miles A.; Holewinski, Adam; Hoyt, Caroline B.

Polymeric amines such as poly(ethylenimine) (PEI) supported on mesoporous oxides are promising candidate adsorbents for CO2 capture processes. An important aspect to the design and optimization of these materials is a fundamental understanding of how the properties of the oxide support such as pore structure, particle morphology, and surface properties affect the efficiency of the guest polymer in its interactions with CO2. Previously, the efficiency of impregnated PEI to adsorb CO2 was shown to increase upon the addition of Zr as a surface modifier in SBA-15. However, the efficacy of this method to tune the adsorption performance has not beenmore » explored in materials of differing textural and morphological nature. Here, these issues are directly addressed via the preparation of an array of SBA-15 support materials with varying textural and morphological properties, as well as varying content of zirconium doped into the material. Zirconium is incorporated into the SBA-15 either during the synthesis of the SBA-15, or postsynthetically via deposition of Zr species onto pure-silica SBA-15. The method of Zr incorporation alters the textural and morphological properties of the parent SBA-15 in different ways. Importantly, the CO2 capacity of SBA-15 impregnated with PEI increases by a maximum of ~60% with the quantity of doped Zr for a “standard” SBA-15 containing significant microporosity, while no increase in the CO2 capacity is observed upon Zr incorporation for an SBA-15 with reduced microporosity and a larger pore size, pore volume, and particle size. Finally, adsorbents supported on SBA-15 with controlled particle morphology show only modest increases in CO2 capacity upon inclusion of Zr to the silica framework. The data demonstrate that the textural and morphological properties of the support have a more significant impact on the ability of PEI to capture CO2 than the support surface composition.« less

Substrate micropatterns produced by polymer demixing regulate focal adhesions, actin anisotropy, and lineage differentiation of stem cells.

PubMed

Vega, Sebastián L; Arvind, Varun; Mishra, Prakhar; Kohn, Joachim; Sanjeeva Murthy, N; Moghe, Prabhas V

2018-06-12

Stem cells are adherent cells whose multipotency and differentiation can be regulated by numerous microenvironmental signals including soluble growth factors and surface topography. This study describes a simple method for creating distinct micropatterns via microphase separation resulting from polymer demixing of poly(desaminotyrosyl-tyrosine carbonate) (PDTEC) and polystyrene (PS). Substrates with co-continuous (ribbons) or discontinuous (islands and pits) PDTEC regions were obtained by varying the ratio of PDTEC and sacrificial PS. Human mesenchymal stem cells (MSCs) cultured on co-continuous PDTEC substrates for 3 days in bipotential adipogenic/osteogenic (AD/OS) induction medium showed no change in cell morphology but exhibited increased anisotropic cytoskeletal organization and larger focal adhesions when compared to MSCs cultured on discontinuous micropatterns. After 14 days in bipotential AD/OS induction medium, MSCs cultured on co-continuous micropatterns exhibited increased expression of osteogenic markers, whereas MSCs on discontinuous PDTEC substrates showed a low expression of adipogenic and osteogenic differentiation markers. Substrates with graded micropatterns were able to reproduce the influence of local underlying topography on MSC differentiation, thus demonstrating their potential for high throughput analysis. This work presents polymer demixing as a simple, non-lithographic technique to produce a wide range of micropatterns on surfaces with complex geometries to influence cellular and tissue regenerative responses. Gaining a better understanding of how engineered microenvironments influence stem cell differentiation is integral to increasing the use of stem cells and materials in a wide range of tissue engineering applications. In this study, we show the range of topography obtained by polymer demixing is sufficient for investigating how surface topography affects stem cell morphology and differentiation. Our findings show that co-continuous topographies favor early (3-day) cytoskeletal anisotropy and focal adhesion maturation as well as long-term (14-day) expression of osteogenic differentiation markers. Taken together, this study presents a simple approach to pattern topographies that induce divergent responses in stem cell morphology and differentiation. Copyright © 2018. Published by Elsevier Ltd.

Biocompatibility of hydroxyapatite coatings deposited by pulse electrodeposition technique on the Nitinol superelastic alloy.

PubMed

Marashi-Najafi, F; Khalil-Allafi, J; Etminanfar, M R

2017-07-01

The present study deals with pulse electrochemical deposition of HA on NiTi alloy and in vitro evaluation of coatings. At first step, a thermo-chemical surface modification process was applied to control the Ni release of the alloy. The electrochemical deposition of CaP coatings was examined at both dilute and concentrated solutions. The morphology and the composition of coatings were studied using scanning electron microscopy (SEM) and Fourier transform infrared spectroscopy (FTIR). Plate like and needle like morphologies were formed for dilute and concentrated solution respectively and HA phase was formed by increasing the pulse current density for both electrolyte. The thickness of the samples was measured using cross sectioning technique. Fibroblast cell culture test on the coated samples revealed that the HA coating obtained by dilute solution shows the best biocompatibility. Also, MTT assay showed the highest cell density and cell proliferation after 5days for the HA coating of dilute solution. The contact angle of samples was measured and the coated samples showed a hydrophilic surface. Soaking the sample in SBF revealed that the crystallization rate of calcium-phosphate compounds is higher on the plate like HA coating as compared to the needle like morphology. The P release of the HA coated samples was measured in a physiological saline solution and the results show that the ions releasing in the plate like coating are less than the needle like coating. It seems that the stability of the plate like coating in biological environments is responsible for the better biocompatibility of the coating. Copyright © 2017 Elsevier B.V. All rights reserved.

A dynamic monitoring approach for the surface morphology evolution measurement of plasma facing components by means of speckle interferometry

NASA Astrophysics Data System (ADS)

Wang, Hongbei; Cui, Xiaoqian; Feng, Chunlei; Li, Yuanbo; Zhao, Mengge; Luo, Guangnan; Ding, Hongbin

2017-11-01

Plasma Facing Components (PFCs) in a magnetically confined fusion plasma device will be exposed to high heat load and particle fluxes, and it would cause PFCs' surface morphology to change due to material erosion and redeposition from plasma wall interactions. The state of PFCs' surface condition will seriously affect the performance of long-pulse or steady state plasma discharge in a tokamak; it will even constitute an enormous threat to the operation and the safety of fusion plasma devices. The PFCs' surface morphology evolution measurement could provide important information about PFCs' real-time status or damage situation and it would help to a better understanding of the plasma wall interaction process and mechanism. Meanwhile through monitoring the distribution of dust deposition in a tokamak and providing an upper limit on the amount of loose dust, the PFCs' surface morphology measurement could indirectly contribute to keep fusion operational limits and fusion device safety. Aiming at in situ dynamic monitoring PFCs' surface morphology evolution, a laboratory experimental platform DUT-SIEP (Dalian University of Technology-speckle interferometry experimental platform) based on the speckle interferometry technique has been constructed at Dalian University of Technology (DUT) in China. With directional specific designing and focusing on the real detection condition of EAST (Experimental Advanced Superconducting Tokamak), the DUT-SIEP could realize a variable measurement range, widely increased from 0.1 μm to 300 μm, with high spatial resolution (<1 mm) and ultra-high time resolution (<2 s for EAST measuring conditions). Three main components of the DUT-SIEP are all integrated and synchronized by a time schedule control and data acquisition terminal and coupled with a three-dimensional phase unwrapping algorithm, the surface morphology information of target samples can be obtained and reconstructed in real-time. A local surface morphology of the real divertor tiles adopted from EAST has been measured, and the feasibility and reliability of this new experimental platform have been demonstrated.

Analysis of high-throughput screening reveals the effect of surface topographies on cellular morphology.

PubMed

Hulsman, Marc; Hulshof, Frits; Unadkat, Hemant; Papenburg, Bernke J; Stamatialis, Dimitrios F; Truckenmüller, Roman; van Blitterswijk, Clemens; de Boer, Jan; Reinders, Marcel J T

2015-03-01

Surface topographies of materials considerably impact cellular behavior as they have been shown to affect cell growth, provide cell guidance, and even induce cell differentiation. Consequently, for successful application in tissue engineering, the contact interface of biomaterials needs to be optimized to induce the required cell behavior. However, a rational design of biomaterial surfaces is severely hampered because knowledge is lacking on the underlying biological mechanisms. Therefore, we previously developed a high-throughput screening device (TopoChip) that measures cell responses to large libraries of parameterized topographical material surfaces. Here, we introduce a computational analysis of high-throughput materiome data to capture the relationship between the surface topographies of materials and cellular morphology. We apply robust statistical techniques to find surface topographies that best promote a certain specified cellular response. By augmenting surface screening with data-driven modeling, we determine which properties of the surface topographies influence the morphological properties of the cells. With this information, we build models that predict the cellular response to surface topographies that have not yet been measured. We analyze cellular morphology on 2176 surfaces, and find that the surface topography significantly affects various cellular properties, including the roundness and size of the nucleus, as well as the perimeter and orientation of the cells. Our learned models capture and accurately predict these relationships and reveal a spectrum of topographies that induce various levels of cellular morphologies. Taken together, this novel approach of high-throughput screening of materials and subsequent analysis opens up possibilities for a rational design of biomaterial surfaces. Copyright © 2015 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

Surface patterning of soft polymer film-coated cylinders via an electric field.

PubMed

Li, Bo; Li, Yue; Xu, Guang-Kui; Feng, Xi-Qiao

2009-11-04

Using the linear stability analysis method, we investigate the surface wrinkling of a thin polymer coating on a cylinder in an externally applied electric field. It is demonstrated that energy competition between surface energy, van der Waals interactive potential energy and electrostatic interaction energy may lead to ordered patterns on the film surface. The analytical solutions are derived for the critical conditions of both longitudinal and circumferential instabilities. The wavelengths of the generated surface patterns can be mediated by changing the magnitude of the electric field. Our analysis shows that the surface morphology is sensitive to the curvature radius of the fiber, especially in the micrometer and nanometer length scales. Furthermore, we suggest a potential approach for fabricating hierarchical patterns on curved surfaces.

Bone Cell–materials Interactions and Ni Ion Release of Anodized Equiatomic NiTi Alloy

PubMed Central

Bernard, Sheldon A.; Balla, Vamsi Krishna; Davies, Neal M.; Bose, Susmita; Bandyopadhyay, Amit

2011-01-01

Laser processed NiTi alloy was anodized for different durations in H2SO4 electrolyte with varying pH to create biocompatible surfaces with low Ni ion release as well as bioactive surfaces to enhance biocompatibility and bone cell-materials interactions. The anodized surfaces were assessed for their in vitro cell-materials interactions using human fetal osteoblast (hFOB) cells for 3, 7 and 11 days, and Ni ion release up to 8 weeks in simulated body fluids. The results were correlated with surface morphologies of anodized surfaces characterized using field-emission scanning electron microscopy (FESEM). The results show that the anodization creates a surface with nano/micro roughness depending on anodization conditions. The hydrophilicity of NiTi surface was found to improve after anodization due to lower contact angles in cell media, which dropped from 32° to < 5°. The improved wettability of anodized surfaces is further corroborated by their high surface energy comparable to that of cp Ti. Relatively high surface energy, especially polar component, and nano/micro surface features of anodized surfaces significantly increased the number of living cells and their adherence and growth on these surfaces. Finally, a significant drop in Ni ion release from 268 ± 11 to 136 ± 15 ppb was observed for NiTi surfaces after anodization. This work indicates that anodization of NiTi alloy has a positive influence on the surface energy and surface morphology, which in turn improve bone cell-materials interactions and reduce Ni ion release in vitro. PMID:21232641

Structure-related antibacterial activity of a titanium nanostructured surface fabricated by glancing angle sputter deposition

NASA Astrophysics Data System (ADS)

Sengstock, Christina; Lopian, Michael; Motemani, Yahya; Borgmann, Anna; Khare, Chinmay; Buenconsejo, Pio John S.; Schildhauer, Thomas A.; Ludwig, Alfred; Köller, Manfred

2014-05-01

The aim of this study was to reproduce the physico-mechanical antibacterial effect of the nanocolumnar cicada wing surface for metallic biomaterials by fabrication of titanium (Ti) nanocolumnar surfaces using glancing angle sputter deposition (GLAD). Nanocolumnar Ti thin films were fabricated by GLAD on silicon substrates. S. aureus as well as E. coli were incubated with nanostructured or reference dense Ti thin film test samples for one or three hours at 37 °C. Bacterial adherence, morphology, and viability were analyzed by fluorescence staining and scanning electron microscopy and compared to human mesenchymal stem cells (hMSCs). Bacterial adherence was not significantly different after short (1 h) incubation on the dense or the nanostructured Ti surface. In contrast to S. aureus the viability of E. coli was significantly decreased after 3 h on the nanostructured film compared to the dense film and was accompanied by an irregular morphology and a cell wall deformation. Cell adherence, spreading and viability of hMSCs were not altered on the nanostructured surface. The results show that the selective antibacterial effect of the cicada wing could be transferred to a nanostructured metallic biomaterial by mimicking the natural nanocolumnar topography.

The polymeric nanofilm of triazinedithiolsilane fabricated by self-assembled technique on copper surface. Part 2: Characterization of composition and morphology

NASA Astrophysics Data System (ADS)

Wang, Yabin; Liu, Zhong; Huang, Yudong; Qi, Yutai

2015-11-01

In the first part, a novel design route for metal protection against corrosion was proposed, and a class of triazinedithiolsilane compounds was conceived as protector for copper. The protective capability of the polymeric nanofilm, fabricated by self-assembling one representative (abbreviated as TESPA) of triazinedithiolsilane compounds onto copper surface, has been investigated and evaluated by electrochemical tests. The results show that the polymeric nanofilm significantly inhibits copper corrosion. This study, on the one hand, concentrates on the chemical composition of the TESPA polymeric nanofilm by means of X-ray photoelectron spectroscopy (XPS). The XPS results reveal that the chemical bonds between copper and TESPA monomers, three dimensional disulfide units and siloxane networks are responsible for the satisfactory protection of TESPA polymeric nanofilm against copper corrosion. On the other hand, scanning electron microscope (SEM) and energy-dispersive spectroscopy (EDS) are utilized to reveal the morphology and the uniformity of the TESPA polymeric nanofilm. The SEM-EDS results demonstrate that the copper surfaces are uniformly covered with TESPA self-assembled monolayer and the polymeric nanofilm. The TESPA-covered copper surfaces turn out to be smoother than that of the bare copper surface.

Morphological covariance in anatomical MRI scans can identify discrete neural pathways in the brain and their disturbances in persons with neuropsychiatric disorders.

PubMed

Bansal, Ravi; Hao, Xuejun; Peterson, Bradley S

2015-05-01

We hypothesize that coordinated functional activity within discrete neural circuits induces morphological organization and plasticity within those circuits. Identifying regions of morphological covariation that are independent of morphological covariation in other regions therefore may therefore allow us to identify discrete neural systems within the brain. Comparing the magnitude of these variations in individuals who have psychiatric disorders with the magnitude of variations in healthy controls may allow us to identify aberrant neural pathways in psychiatric illnesses. We measured surface morphological features by applying nonlinear, high-dimensional warping algorithms to manually defined brain regions. We transferred those measures onto the surface of a unit sphere via conformal mapping and then used spherical wavelets and their scaling coefficients to simplify the data structure representing these surface morphological features of each brain region. We used principal component analysis (PCA) to calculate covariation in these morphological measures, as represented by their scaling coefficients, across several brain regions. We then assessed whether brain subregions that covaried in morphology, as identified by large eigenvalues in the PCA, identified specific neural pathways of the brain. To do so, we spatially registered the subnuclei for each eigenvector into the coordinate space of a Diffusion Tensor Imaging dataset; we used these subnuclei as seed regions to track and compare fiber pathways with known fiber pathways identified in neuroanatomical atlases. We applied these procedures to anatomical MRI data in a cohort of 82 healthy participants (42 children, 18 males, age 10.5 ± 2.43 years; 40 adults, 22 males, age 32.42 ± 10.7 years) and 107 participants with Tourette's Syndrome (TS) (71 children, 59 males, age 11.19 ± 2.2 years; 36 adults, 21 males, age 37.34 ± 10.9 years). We evaluated the construct validity of the identified covariation in morphology using DTI data from a different set of 20 healthy adults (10 males, mean age 29.7 ± 7.7 years). The PCA identified portions of structures that covaried across the brain, the eigenvalues measuring the magnitude of the covariation in morphology along the respective eigenvectors. Our results showed that the eigenvectors, and the DTI fibers tracked from their associated brain regions, corresponded with known neural pathways in the brain. In addition, the eigenvectors that captured morphological covariation across regions, and the principal components along those eigenvectors, identified neural pathways with aberrant morphological features associated with TS. These findings suggest that covariations in brain morphology can identify aberrant neural pathways in specific neuropsychiatric disorders. Copyright © 2015. Published by Elsevier Inc.

Effect of calcination temperature on the photocatalytic reduction and oxidation processes of hydrothermally synthesized titania nanotubes.

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

Viayan, B.; Dimitrijevic, N. M.; Rajh, T.

Titania nanotubes having diameters 8 to 12 nm and lengths of 50-300 nm were prepared using a hydrothermal method. Further, the titania nanotubes were calcined over the temperature range 200-800 C in order to enhance their photocatalytic properties by altering their morphology. The calcined titania nanotubes were characterized by using X-ray diffraction and surface area analysis and their morphological features were studied by scanning and transmission electron microscopy. Nanotubes calcined at 400 C showed the maximum extent of photocatalyitc reduction of carbon dioxide to methane, whereas samples calcined at 600 C produced maximum photocatalytic oxidation of acetaldehyde. Electron paramagnetic resonancemore » (EPR) spectroscopy was used to interrogate the effects of nanotube structure on the charge separation and trapping as a function of calcination temperature. EPR results indicated that undercoordinated titania sites are associated with maximum CO{sub 2} reduction occurring in nanotubes calcined at 400 C. Despite the collapse of the nantube structure to form nanorods and the concomitant loss of surface area, the enhanced charge separation associated with increased crystallinity promoted high rates of oxidation of acetaldehyde in titania materials calcined at 600 C. These results illustrate that calcination temperature allows us to tune the morphological and surface features of the titania nanostructures for particular photocatalytic reactions.« less

Nitric acid passivation does not affect in vitro biocompatibility of titanium.

PubMed

Faria, Adriana C L; Beloti, Márcio M; Rosa, Adalberto L

2003-01-01

In general, both chemical composition and surface features of implants affect cell response. The aim of this study was to evaluate the effect of titanium (Ti) passivation on the response of rat bone marrow cells, considering cell attachment, cell morphology, cell proliferation, total protein content, alkaline phosphatase (ALP) activity, and bonelike nodule formation. Cells were cultured on both commercially pure titanium (cpTi) and titanium-aluminium-vanadium alloy (Ti-6Al-4V) discs, either passivated or not. For attachment evaluation, cells were cultured for 4 and 24 hours. Cell morphology was evaluated after 4 days. After 7, 14, and 21 days, cell proliferation, total protein content, and ALP activity were evaluated. Bonelike nodule formation was evaluated after 21 days. Data were compared by analysis of variance and the Duncan multiple range test. Cell attachment, cell morphology, cell proliferation, total protein content, ALP activity, and bonelike nodule formation all were unaffected by Ti composition or passivation. Although the protocol for passivation used here could interfere with the pattern of ions released from Ti-6Al-4V and cpTi surfaces, the present study did not show any effect of this surface treatment on in vitro biocompatibility of Ti as evaluated by osteoblast attachment, proliferation, and differentiation.

Controlled growth of standing Ag nanorod arrays on bare Si substrate using glancing angle deposition for self-cleaning applications

NASA Astrophysics Data System (ADS)

Singh, Dhruv P.; Singh, J. P.

2014-03-01

A facile approach to manipulate the hydrophobicity of surface by controlled growth of standing Ag nanorod arrays is presented. Instead of following the complicated conventional method of the template-assisted growth, the morphology or particularly average diameter and number density (nanorods cm-2) of nanorods were controlled on bare Si substrate by simply varying the deposition rate during glancing angle deposition. The contact angle measurements showed that the evolution of Ag nanorods reduces the surface energy and makes an increment in the apparent water contact angle compared to the plain Ag thin film. The contact angle was found to increase for the Ag nanorod samples grown at lower deposition rates. Interestingly, the morphology of the nanorod arrays grown at very low deposition rate (1.2 Å sec-1) results in a self-cleaning superhydrophobic surface of contact angle about 157° and a small roll-off angle about 5°. The observed improvement in hydrophobicity with change in the morphology of nanorod arrays is explained as the effect of reduction in solid fraction within the framework of Cassie-Baxter model. These self-cleaning Ag nanorod arrays could have a significant impact in wide range of applications such as anti-icing coatings, sensors and solar panels.

Effect of Coating Thickness on the Properties of TiN Coatings Deposited on Tool Steels Using Cathodic Arc Pvd Technique

NASA Astrophysics Data System (ADS)

Mubarak, A.; Akhter, Parvez; Hamzah, Esah; Mohd Toff, Mohd Radzi Hj.; Qazi, Ishtiaq A.

Titanium nitride (TiN) widely used as hard coating material, was coated on tool steels, namely on high-speed steel (HSS) and D2 tool steel by physical vapor deposition method. The study concentrated on cathodic arc physical vapor deposition (CAPVD), a technique used for the deposition of hard coatings for tooling applications, and which has many advantages. The main drawback of this technique, however, is the formation of macrodroplets (MDs) during deposition, resulting in films with rougher morphology. Various standard characterization techniques and equipment, such as electron microscopy, atomic force microscopy, hardness testing machine, scratch tester, and pin-on-disc machine, were used to analyze and quantify the following properties and parameters: surface morphology, thickness, hardness, adhesion, and coefficient of friction (COF) of the deposited coatings. Surface morphology revealed that the MDs produced during the etching stage, protruded through the TiN film, resulting in film with deteriorated surface features. Both coating thickness and indentation loads influenced the hardness of the deposited coatings. The coatings deposited on HSS exhibit better adhesion compared to those on D2 tool steel. Standard deviation indicates that the coating deposited with thickness around 6.7 μm showed the most stable trend of COF versus sliding distance.

Construction of Zinc Oxide into Different Morphological Structures to Be Utilized as Antimicrobial Agent against Multidrug Resistant Bacteria

PubMed Central

Elkady, M. F.; Shokry Hassan, H.; Hafez, Elsayed E.; Fouad, Ahmed

2015-01-01

Nano-ZnO has been successfully implemented in particles, rods, and tubes nanostructures via sol-gel and hydrothermal techniques. The variation of the different preparation parameters such as reaction temperature, time, and stabilizer agents was optimized to attain different morphological structures. The influence of the microwave annealing process on ZnO crystallinity, surface area, and morphological structure was monitored using XRD, BET, and SEM techniques, respectively. The antimicrobial activity of zinc oxide produced in nanotubes structure was examined against four different multidrug resistant bacteria: Gram-positive (Staphylococcus aureus and Bacillus subtilis) and Gram-negative (Escherichia coli and Pseudomonas aeruginosa) strains. The activity of produced nano-ZnO was determined by disc diffusion technique and the results revealed that ZnO nanotubes recorded high activity against the studied strains due to their high surface area equivalent to 17.8 m2/g. The minimum inhibitory concentration (MIC) of ZnO nanotubes showed that the low concentrations of ZnO nanotubes could be a substitution for the commercial antibiotics when approached in suitable formula. Although the annealing process of ZnO improves the degree of material crystallinity, however, it declines its surface area and consequently its antimicrobial activity. PMID:26451136

Effect of RF power and annealing on chemical bonding and morphology of a-CN{sub x} thin films as humidity sensor

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

Aziz, N. F. H; Hussain, N. S. Mohamed; Awang, R.

2013-11-27

Amorphous carbon nitride (a-CN{sub x}) thin films were deposited using radio frequency plasma enhanced chemical vapor deposition (rf-PECVD) technique. A set of a-CN{sub x} thin films were prepared using pure methane (CH{sub 4}) gas diluted with nitrogen (N{sub 2}) gas. The rf power was varied at 50, 60, 70, 80, 90 and 100 W. These films were then annealed at 400 °C in a quartz tube furnace in argon (Ar) gas. The effects of rf power and thermal annealing on the chemical bonding and morphology of these samples were studied. Surface profilometer was used to measure film thickness. Fourier transformmore » infra-red spectroscopy (FTIR) and Field emission scanning electron microscopy (FESEM) measurements were used to determine their chemical bonding and morphology respectively. The deposition rate of the films increased constantly with increasing rf power up to 80W, before decreasing with further increase in rf power. Fourier transform infra-red spectroscopy (FTIR) studies showed a systematic change in the spectra and revealed three main peaks included C-N, C=N, C=C and C≡N triple bond. C=N and C≡N bonds decreased with increased C-N bonds after thermal annealing process. The FESEM images showed that the structure is porous for as-deposited and covered by granule-like grain structure after thermal annealing process was done. The resistance of the a-CN{sub x} thin film changed from 23.765 kΩ to 5.845 kΩ in the relative humidity range of 5 to 92 % and the film shows a good response and repeatability as a humidity sensing materials. This work showed that rf power and thermal annealing has significant effects on the chemical bonding and surface morphology of the a-CN{sub x} films and but yield films which are potential candidate as humidity sensor device.« less

Suppression of surface microstructure evolution in W and W-Ta alloys during simultaneous and sequential He and D ion irradiation in fusion relevant conditions

NASA Astrophysics Data System (ADS)

Gonderman, S.; Tripathi, J. K.; Sizyuk, T.; Hassanein, A.

2017-08-01

Tungsten (W) has been selected as the divertor material in ITER based on its promising thermal and mechanical properties. Despite these advantages, continued investigation has revealed W to undergo extreme surface morphology evolution in response to relevant fusion operating conditions. These complications spur the need for further exploration of W and other innovative plasma facing components (PFCs) for future fusion devices. Recent literature has shown that alloying of W with other refractory metals, such as tantalum (Ta), results in the enhancement of key PFC properties including, but not limited to, ductility, hydrogen isotope retention, and helium ion (He+) radiation tolerance. In the present study, pure W and W-Ta alloys are exposed to simultaneous and sequential low energy, He+ and deuterium (D+) ion beam irradiations at high (1223 K) and low (523 K) temperatures. The goal of this study is to cultivate a complete understanding of the synergistic effects induced by dual and sequential ion irradiation on W and W-Ta alloy surface morphology evolution. For the dual ion beam experiments, W and W-Ta samples were subjected to four different He+: D+ ion ratios (100% He+, 60% D+  +  40% He+, 90% D+  +  10% He+ and 100% D+) having a total constant He+ fluence of 6  ×  1024 ion m-2. The W and W-Ta samples both exhibit the expected damaged surfaces under the 100% He+ irradiation, but as the ratio of D+/He+ ions increases there is a clear suppression of the surface morphology at high temperatures. This observation is supported by the sequential experiments, which show a similar suppression of surface morphology when W and W-Ta samples are first exposed to low energy He+ irradiation and then exposed to subsequent low energy D+ irradiation at high temperatures. Interestingly, this morphology suppression is not observed at low temperatures, implying there is a D-W interaction mechanism which is dependent on temperature that is driving the suppression of the microstructure evolution in both the pure W and W-Ta alloys. Minor irradiation tolerance enhancement in the performance of the W-Ta samples is also observed.

Morphological evolution in a strained-heteroepitaxial solid droplet on a rigid substrate: Dynamical simulations

NASA Astrophysics Data System (ADS)

Ogurtani, Tarik Omer; Celik, Aytac; Oren, Ersin Emre

2010-09-01

A systematic study based on the self-consistent dynamical simulations is presented for the spontaneous evolution of an isolated thin solid droplet (bump) on a rigid substrate, which is driven by the surface drift diffusion induced by the capillary and mismatch stresses. In this study, we mainly focused on the development kinetics of the "Stranski-Krastanow" island type morphology, initiated by the nucleation route rather than the surface roughening scheme. The physicomathematical model, which bases on the irreversible thermodynamics treatment of surfaces and interfaces with singularities [T. O. Ogurtani, J. Chem. Phys. 124, 144706 (2006)], furnishes us to have autocontrol on the otherwise free-motion of the triple junction contour line between the substrate and the droplet without presuming any equilibrium dihedral contract (wetting) angles at the edges. During the development of the bell-shaped Stranski-Krastanow island through the mass accumulation at the central region of the droplet via surface drift diffusion with and/or without growth, the formation of an extremely thin wetting layer is observed. This wetting layer has a thickness of a fraction of a nanometer and covers not only the initial computation domain but also its further extension beyond the original boundaries. We also observed the formation of the multiple islands separated by shallow wetting layers above a certain threshold level of the mismatch strain and/or the size (i.e., volume) of the droplets. This threshold level depends on the initial physicochemical data and the aspect ratio (i.e., shape) of the original droplets. During the course of the simulations, we continuously tracked both the morphology (i.e., the peak height, the extension of the wetting layer beyond the domain boundaries, and the triple junction contact angle) and energetic (the global Helmholtz free energy changes associated with the total strain and surface energy variations) in the system. We observed that the morphology related quantities are reaching certain saturation limits or plateaus, when the growth mode is turned-off. On the other hand, the global Helmholtz free energy showed a steady decrease in time even though the total surface free energy of the droplet reaches a stationary value as expected a priori. Based on these observations and according to the accepted irreversible thermodynamic terminology as coined by celebrated Prigogine, we state that the Stranski-Krastanow type island morphologies are genuine stationary nonequilibrium states.

Influence of surface morphology on the immersion mode ice nucleation efficiency of hematite particles

NASA Astrophysics Data System (ADS)

Hiranuma, N.; Hoffmann, N.; Kiselev, A.; Dreyer, A.; Zhang, K.; Kulkarni, G.; Koop, T.; Möhler, O.

2014-03-01

In this paper, the effect of the morphological modification of aerosol particles with respect to heterogeneous ice nucleation is comprehensively investigated for laboratory-generated hematite particles as a model substrate for atmospheric dust particles. The surface-area-scaled ice nucleation efficiencies of monodisperse cubic hematite particles and milled hematite particles were measured with a series of expansion cooling experiments using the Aerosol Interaction and Dynamics in the Atmosphere (AIDA) cloud simulation chamber. Complementary offline characterization of physico-chemical properties of both hematite subsets were also carried out with scanning electron microscopy (SEM), energy dispersive X-ray (EDX) spectroscopy, dynamic light scattering (DLS), and an electro-kinetic particle charge detector to further constrain droplet-freezing measurements of hematite particles. Additionally, an empirical parameterization derived from our laboratory measurements was implemented in the single-column version of the Community Atmospheric Model version 5 (CAM5) to investigate the model sensitivity in simulated ice crystal number concentration on different ice nucleation efficiencies. From an experimental perspective, our results show that the immersion mode ice nucleation efficiency of milled hematite particles is almost an order of magnitude higher at -35.2 °C < T < -33.5 °C than that of the cubic hematite particles, indicating a substantial effect of morphological irregularities on immersion mode freezing. Our modeling results similarly show that the increased droplet-freezing rates of milled hematite particles lead to about one order magnitude higher ice crystal number in the upper troposphere than cubic hematite particles. Overall, our results suggest that the surface irregularities and associated active sites lead to greater ice activation through droplet freezing.

Deposition and characterization of molybdenum thin films using dc-plasma magnetron sputtering

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

Khan, Majid, E-mail: majids@hotmail.com; Islam, Mohammad, E-mail: mohammad.islam@gmail.com

2013-12-15

Molebdenum (Mo) thin films were deposited on well-cleaned soda-lime glass substrates using DC-plasma magnetron sputtering. In the design of experiment deposition was optimized for maximum beneficial characteristics by monitoring effect of process variables such as deposition power (100–200 W). Their electrical, structural and morphological properties were analyzed to study the effect of these variables. The electrical resistivity of Mo thin films could be reduced by increasing deposition power. Within the range of analyzed deposition power, Mo thin films showed a mono crystalline nature and the crystallites were found to have an orientation along [110] direction. The surface morphology of thinmore » films showed that a highly dense micro structure has been obtained. The surface roughness of films increased with deposition power. The adhesion of Mo thin films could be improved by increasing the deposition power. Atomic force microscopy was used for the topographical study of the films and to determine the roughness of the films. X-ray diffractrometer and scanning electron microscopy analysis were used to investigate the crystallinity and surface morphology of the films. Hall effect measurement system was used to find resistivity, carrier mobility and carrier density of deposited films. The adhesion test was performed using scotch hatch tape adhesion test. Mo thin films prepared at deposition power of 200 W, substrate temperature of 23°C and Ar pressure of 0.0123 mbar exhibited a mono crystalline structure with an orientation along (110) direction, thickness of ∼550 nm and electrical resistivity value of 0.57 × 10{sup −4} Ω cm.« less

[Effects of tree species diversity on fine-root biomass and morphological characteristics in subtropical Castanopsis carlesii forests].

PubMed

Wang, Wei-Wei; Huang, Jin-Xue; Chen, Feng; Xiong, De-Cheng; Lu, Zheng-Li; Huang, Chao-Chao; Yang, Zhi-Jie; Chen, Guang-Shui

2014-02-01

Fine roots in the Castanopsis carlesii plantation forest (MZ), the secondary forest of C. carlesii through natural regeneration with anthropogenic promotion (AR), and the secondary forest of C. carlesii through natural regeneration (NR) in Sanming City, Fujian Province, were estimated by soil core method to determine the influence of tree species diversity on biomass, vertical distribution and morphological characteristics of fine roots. The results showed that fine root biomass for the 0-80 cm soil layer in the MZ, AR and NR were (182.46 +/- 10.81), (242.73 +/- 17.85) and (353.11 +/- 16.46) g x m(-2), respectively, showing an increased tendency with increasing tree species diversity. In the three forests, fine root biomass was significantly influenced by soil depth, and fine roots at the 0-10 cm soil layer accounted for more than 35% of the total fine root biomass. However, the interaction of stand type and soil depth on fine-root distribution was not significant, indicating no influence of tree species diversity on spatial niche segregation in fine roots. Root surface area density and root length density were the highest in NR and lowest in the MZ. Specific root length was in the order of AR > MZ > NR, while specific root surface area was in the order of NR > MZ > AR. There was no significant interaction of stand type and soil depth on specific root length and specific root surface area. Fine root morphological plasticity at the stand level had no significant response to tree species diversity.

Probing stochastic inter-galactic magnetic fields using blazar-induced gamma ray halo morphology

NASA Astrophysics Data System (ADS)

Duplessis, Francis; Vachaspati, Tanmay

2017-05-01

Inter-galactic magnetic fields can imprint their structure on the morphology of blazar-induced gamma ray halos. We show that the halo morphology arises through the interplay of the source's jet and a two-dimensional surface dictated by the magnetic field. Through extensive numerical simulations, we generate mock halos created by stochastic magnetic fields with and without helicity, and study the dependence of the halo features on the properties of the magnetic field. We propose a sharper version of the Q-statistics and demonstrate its sensitivity to the magnetic field strength, the coherence scale, and the handedness of the helicity. We also identify and explain a new feature of the Q-statistics that can further enhance its power.

Prospective in (Primate) Dental Analysis through Tooth 3D Topographical Quantification

PubMed Central

Guy, Franck; Gouvard, Florent; Boistel, Renaud; Euriat, Adelaïde; Lazzari, Vincent

2013-01-01

The occlusal morphology of the teeth is mostly determined by the enamel-dentine junction morphology; the enamel-dentine junction plays the role of a primer and conditions the formation of the occlusal enamel reliefs. However, the accretion of the enamel cap yields thickness variations that alter the morphology and the topography of the enamel–dentine junction (i.e., the differential deposition of enamel by the ameloblasts create an external surface that does not necessarily perfectly parallel the enamel–dentine junction). This self-reliant influence of the enamel on tooth morphology is poorly understood and still under-investigated. Studies considering the relationship between enamel and dentine morphologies are rare, and none of them tackled this relationship in a quantitative way. Major limitations arose from: (1) the difficulties to characterize the tooth morphology in its comprehensive tridimensional aspect and (2) practical issues in relating enamel and enamel–dentine junction quantitative traits. We present new aspects of form representation based exclusively on 3D analytical tools and procedures. Our method is applied to a set of 21 unworn upper second molars belonging to eight extant anthropoid genera. Using geometrical analysis of polygonal meshes representatives of the tooth form, we propose a 3D dataset that constitutes a detailed characterization of the enamel and of the enamel–dentine junction morphologies. Also, for the first time, to our knowledge, we intend to establish a quantitative method for comparing enamel and enamel–dentine junction surfaces descriptors (elevation, inclination, orientation, etc.). New indices that allow characterizing the occlusal morphology are proposed and discussed. In this note, we present technical aspects of our method with the example of anthropoid molars. First results show notable individual variations and taxonomic heterogeneities for the selected topographic parameters and for the pattern and strength of association between enamel–dentine junction and enamel, the enamel cap altering in different ways the “transcription” of the enamel–dentine junction morphology. PMID:23826088

Numerical modeling of salt marsh morphological change induced by Hurricane Sandy

USGS Publications Warehouse

Hu, Kelin; Chen, Qin; Wang, Hongqing; Hartig, Ellen K.; Orton, Philip M.

2018-01-01

The salt marshes of Jamaica Bay serve as a recreational outlet for New York City residents, mitigate wave impacts during coastal storms, and provide habitat for critical wildlife species. Hurricanes have been recognized as one of the critical drivers of coastal wetland morphology due to their effects on hydrodynamics and sediment transport, deposition, and erosion processes. In this study, the Delft3D modeling suite was utilized to examine the effects of Hurricane Sandy (2012) on salt marsh morphology in Jamaica Bay. Observed marsh elevation change and accretion from rod Surface Elevation Tables and feldspar Marker Horizons (SET-MH) and hydrodynamic measurements during Hurricane Sandy were used to calibrate and validate the wind-waves-surge-sediment transport-morphology coupled model. The model results agreed well with in situ field measurements. The validated model was then used to detect salt marsh morphological change due to Sandy across Jamaica Bay. Model results indicate that the island-wide morphological changes in the bay's salt marshes due to Sandy were in the range of −30 mm (erosion) to +15 mm (deposition), and spatially complex and heterogeneous. The storm generated paired deposition and erosion patches at local scales. Salt marshes inside the west section of the bay showed erosion overall while marshes inside the east section showed deposition from Sandy. The net sediment amount that Sandy brought into the bay is only about 1% of the total amount of reworked sediment within the bay during the storm. Numerical experiments show that waves and vegetation played a critical role in sediment transport and associated wetland morphological change in Jamaica Bay. Furthermore, without the protection of vegetation, the marsh islands of Jamaica Bay would experience both more erosion and less accretion in coastal storms.

Minimizing residues and strain in 2D materials transferred from PDMS.

PubMed

Jain, Achint; Bharadwaj, Palash; Heeg, Sebastian; Parzefall, Markus; Taniguchi, Takashi; Watanabe, Kenji; Novotny, Lukas

2018-06-29

Integrating layered two-dimensional (2D) materials into 3D heterostructures offers opportunities for novel material functionalities and applications in electronics and photonics. In order to build the highest quality heterostructures, it is crucial to preserve the cleanliness and morphology of 2D material surfaces that come in contact with polymers such as PDMS during transfer. Here we report that substantial residues and up to ∼0.22% compressive strain can be present in monolayer MoS 2 transferred using PDMS. We show that a UV-ozone pre-cleaning of the PDMS surface before exfoliation significantly reduces organic residues on transferred MoS 2 flakes. An additional 200 ◦ C vacuum anneal after transfer efficiently removes interfacial bubbles and wrinkles as well as accumulated strain, thereby restoring the surface morphology of transferred flakes to their native state. Our recipe is important for building clean heterostructures of 2D materials and increasing the reproducibility and reliability of devices based on them.

Adhesion modification of neural stem cells induced by nanoscale ripple patterns

NASA Astrophysics Data System (ADS)

Pedraz, P.; Casado, S.; Rodriguez, V.; Giordano, M. C.; Buatier de Mongeot, F.; Ayuso-Sacido, A.; Gnecco, E.

2016-03-01

We have studied the influence of anisotropic nanopatterns (ripples) on the adhesion and morphology of mouse neural stem cells (C17.2) on glass substrates using cell viability assay, optical microscopy and atomic force microscopy. The ripples were produced by defocused ion beam sputtering with inert Ar ions, which physically remove atoms from the surface at the energy of 800 eV. The ripple periodicity (∼200 nm) is comparable to the thickness of the cytoplasmatic microspikes (filopodia) which link the stem cells to the substrate. All methods show that the cell adhesion is significantly lowered compared to the same type of cells on flat glass surfaces. Furthermore, the AFM analysis reveals that the filopodia tend to be trapped parallel or perpendicular to the ripples, which limits the spreading of the stem cell on the rippled substrate. This opens the perspective of controlling the micro-adhesion of stem cells and the orientation of their filopodia by tuning the anisotropic substrate morphology without chemical reactions occurring at the surface.

Nanoparticle induced piezoelectric, super toughened, radiation resistant, multi-functional nanohybrids.

PubMed

Tiwari, Vimal K; Shripathi, T; Lalla, N P; Maiti, Pralay

2012-01-07

We have developed multifunctional nanohybrids of poly(vinylidene fluoride-co-chlorotrifluoroethylene) (CTFE) with a small percentage of surface modified inorganic layered silicate showing dramatic improvement in toughness, radiation resistant and piezoelectric properties vis-à-vis pristine polymer. Massive intercalation (d(001) 1.8 → 3.9 nm) of polymer inside the nanoclay galleries and unique crystallization behavior of the fluoropolymer on the surface of individual silicate layer has been reported. Toughness in the nanohybrid increases more than three orders of magnitude as compared to pure CTFE. High energy radiation (80 MeV Si(+7)) causes chain session, amorphization and creates olefinic bonds in the pure polymer while the nanohybrids are radiation resistant at a similar dose. Nanoclay induces the metastable piezoelectric β-phase in CTFE, suitable for sensor and actuator application. Molecular level changes after irradiation and controlled morphology for smart membrane have been confirmed by using spectroscopy, sol-gel technique, surface morphology studies and in situ residual gas analysis.

Effect of corona discharge on cadmium sulphide and lead sulphide films

NASA Astrophysics Data System (ADS)

Koul Chaku, Anemone; Singh, Pramod K.; Bhattacharya, Bhaskar

2018-03-01

This paper describes the effect of corona discharge on cadmium sulphide (CdS) and lead sulphide (PbS) films prepared using the chemical route. The property of films before and after exposure to corona has been described in detail. The electronic properties of the CdS and PbS films have been studied by current-voltage (I-V), capacitance-voltage (C-V) measurements. The structural properties and surface morphology were studied by using X-ray diffraction and scanning electron microscopy before and after exposing to Corona discharge. The films displayed the change in surface morphology after exposure to the corona discharge. It has been found that the films showed an increase in resistivity after exposure. This change in property has been attributed to modification in surface states. Time-dependent recovery indicated that room temperature annealing is sufficient to regain the normal resistivity of the films. The experiment was carried with the aim of studying the effect of the interaction of corona discharge on the semiconductor films and its subsequent effects.

Study of heat-moisture treatment of potato starch granules by chemical surface gelatinization.

PubMed

Bartz, Josiane; da Rosa Zavareze, Elessandra; Dias, Alvaro Renato Guerra

2017-08-01

Native potato starch was subjected to heat-moisture treatment (HMT) at 12%, 15%, 18%, 21%, and 24% of moisture content at 110 °C for 1 h, and the effects on morphology, structure, and thermal and physicochemical properties were investigated. To reveal the internal structure, 30% and 50% of the granular surface were removed by chemical surface gelatinization in concentrated LiCl solution. At moisture contents of 12% and 15%, HTM reduced the gelatinization temperatures and relative crystallinity of the starches, while at moisture contents of 21% and 24 % both increased. The alterations on morphology, X-ray pattern, physicochemical properties, and increase of amylose content were more intense with the increase of moisture content of HMT. The removal of granular layers showed that the changes promoted by HMT occur throughout the whole granule and were pronounced at the core or peripheral region, depending of the moisture content applied during HMT. © 2016 Society of Chemical Industry. © 2016 Society of Chemical Industry.

Morphology of viscoplastic drop impact on viscoplastic surfaces.

PubMed

Chen, Simeng; Bertola, Volfango

2017-01-25

The impact of viscoplastic drops onto viscoplastic substrates characterized by different magnitudes of the yield stress is investigated experimentally. The interaction between viscoplastic drops and surfaces has an important application in additive manufacturing, where a fresh layer of material is deposited on a partially cured or dried layer of the same material. So far, no systematic studies on this subject have been reported in literature. The impact morphology of different drop/substrate combinations, with yield stresses ranging from 1.13 Pa to 11.7 Pa, was studied by high speed imaging for impact Weber numbers between 15 and 85. Experimental data were compared with one of the existing models for Newtonian drop impact onto liquid surfaces. Results show the magnitude of the yield stress of drop/substrate strongly affects the final shape of the impacting drop, permanently deformed at the end of impact. The comparison between experimental data and model predictions suggests the crater evolution model is only valid when predicting the evolution of the crater at sufficiently high Weber numbers.

Minimizing residues and strain in 2D materials transferred from PDMS

NASA Astrophysics Data System (ADS)

Jain, Achint; Bharadwaj, Palash; Heeg, Sebastian; Parzefall, Markus; Taniguchi, Takashi; Watanabe, Kenji; Novotny, Lukas

2018-06-01

Integrating layered two-dimensional (2D) materials into 3D heterostructures offers opportunities for novel material functionalities and applications in electronics and photonics. In order to build the highest quality heterostructures, it is crucial to preserve the cleanliness and morphology of 2D material surfaces that come in contact with polymers such as PDMS during transfer. Here we report that substantial residues and up to ∼0.22% compressive strain can be present in monolayer MoS2 transferred using PDMS. We show that a UV-ozone pre-cleaning of the PDMS surface before exfoliation significantly reduces organic residues on transferred MoS2 flakes. An additional 200 ◦C vacuum anneal after transfer efficiently removes interfacial bubbles and wrinkles as well as accumulated strain, thereby restoring the surface morphology of transferred flakes to their native state. Our recipe is important for building clean heterostructures of 2D materials and increasing the reproducibility and reliability of devices based on them.

The Case for Cryovolcanism on Saturns Moon Titan

NASA Astrophysics Data System (ADS)

Nelson, R. M.

2009-04-01

Two regions on the surface of Saturn's satellite Titan have been observed to change reflectance during the Cassini spacecraft's four-year, orbital tour of the Saturnian system. These changes were documented by Cassini's Visual and Infrared Mapping Spectrometer. Titan's atmosphere is opaque at visual wavelengths due to methane, but VIMS is able to image the surface through "windows" at infrared wavelengths where the methane is relatively transparent[1,2]. Cassini RADAR images show that at least one of these regions, Hotei Arcus (26S,78W), exhibits lobate "flow" forms, consistent with the morphology of volcanic terrain [3]. Here we report the discovery of additional lobate "flow" patterns on Titan's surface at Hotei Arcus, based on VIMS images recently obtained during close flybys by Cassini. This new evidence, combined with the previous evidence from RADAR images, together with the earlier brightness variability seen at these same locations by VIMS, supports the hypothesis of volcanic eruptions. If so, then Titan is presently geologically active on the surface, and in its interior. Cassini encountered Titan at very close range on 2008-11-19-13:58 and again on 2008-12-05-12:38. These epochs are called T47 and T48. The slant distance from the spacecraft to Hotei Arcus was 27,051 and 31,787 km. for T47 and T48 respectively. We report changes that occurred since the T5 flyby (2005-04-16-13:17; range 117042 km). Previously, VIMS was able to see brightness changes but not morphological change. Now, comparison of earlier higher-resolution data (T5) with the recent T47 and T48 data reveal changes of the surface reflectance and morphology in the Hotei region. This is the first evidence from VIMS that shows that Hotei Arcus is morphology consistent with volcanic terrain. If Titan is currently active then these results raise for discussion the following questions: What is the full extent of current geologic activity? What are the ongoing processes? Are Titan's chemical processes today supporting a prebiotic chemistry similar to that under which life evolved on Earth? References: [1]R. M. Nelson et al., 2008a accepted in Icarus [2]R. M. Nelson et al., 2008b accepted in GRL. [3]S. D. Wall et al. 2009 accepted in GRL. This work performed at JPL under contract with NASA.

Physical and biological characterization of sericin-loaded copolymer liposomes stabilized by polyvinyl alcohol.

PubMed

Suktham, Kunat; Koobkokkruad, Thongchai; Saesoo, Somsak; Saengkrit, Nattika; Surassmo, Suvimol

2016-12-01

Sericin protein (SP) is widely used as a nutrient biomaterial for biomedical and cosmeceutical applications although it shows low stability to heat and light. To overcome these problems and add value to wastewater from the silk industry, sericin protein was recovered as sericin-loaded copolymer-liposomes (SP-PVA-LP), prepared through thin film hydration. The size and morphology of the liposomes were investigated using dynamic light scattering (DLS), and electron microscopy (SEM and TEM). The particle size, liposome surface morphology and encapsulation efficiency of SP were dependent on PVA concentration. The hydrodynamic size of the nanoparticles was between 200 and 400nm, with the degree of negative charge contingent on sericin loading. SEM and TEM images confirmed the mono-dispersity, and spherical nature of the particles, with FTIR measurements confirming the presence of surface bound PVA. Exposure of liposomes to 500ppm sericin highlighted a dependence of encapsulation efficiency on PVA content; 2% surface PVA proved the optimal level for sericin loading. Cytotoxicity and viability assays revealed that SP-loaded surface modified liposomes promote cellular attachment and proliferation of human skin fibroblasts without adverse toxic effects. Surface modified copolymer liposomes show high performance in maintaining structural stability, and promoting enhancements in the solubility and bio-viability of sericin. Taken together, these biocompatible constructs allow for effective controlled release, augmenting sericin activity and resulting in effective drug delivery systems. Copyright © 2016 Elsevier B.V. All rights reserved.

Poly(styrene-co-butadiene) random copolymer thin films and nanostructures on a mica surface: morphology and contact angles of nanodroplets.

PubMed

McClements, Jake; Buffone, Cosimo; Shaver, Michael P; Sefiane, Khellil; Koutsos, Vasileios

2017-09-20

The self-assembly of poly(styrene-co-butadiene) random copolymers on mica surfaces was studied by varying solution concentrations and polymer molecular weights. Toluene solutions of the poly(styrene-co-butadiene) samples were spin coated onto a mica surface and the resulting polymer morphology was investigated by atomic force microscopy. At higher concentrations, thin films formed with varying thicknesses; some dewetting was observed which depended on the molecular weight. Total dewetting did not occur despite the polymer's low glass transition temperature. Instead, partial dewetting was observed suggesting that the polymer was in a metastable equilibrium state. At lower concentrations, spherical cap shaped nanodroplets formed with varying sizes from single polymer chains to aggregates containing millions of chains. As the molecular weight was increased, fewer aggregates were observed on the surface, albeit with larger sizes resulting from increased solution viscosities and more chain entanglements at higher molecular weights. The contact angles of the nanodroplets were shown to be size dependent. A minimum contact angle occurs for droplets with radii of 100-250 nm at each molecular weight. Droplets smaller than 100 nm showed a sharp increase in contact angle; attributed to an increase in the elastic modulus of the droplets, in addition, to a positive line tension value. Droplets larger than 250 nm also showed an increased contact angle due to surface heterogeneities which cannot be avoided for larger droplets. This increase in contact angle plateaus as the droplet size reaches the macroscopic scale.

Bedload fluctuations in a steep macro-rough channel

NASA Astrophysics Data System (ADS)

Ghilardi, Tamara; Franca, Mário J.; Schleiss, Anton J.

2014-05-01

It is known that bedload fluctuates over time in steep rivers with wide grain size distributions, even when conditions of constant sediment feed and water discharge are met. Bedload fluctuations are periodic and related to fluctuations in the flow velocity and channel bed morphology. In cascade morphologies, the presence of large relatively immobile boulders has a strong impact on flow conditions and sediment transport; their influence on bedload fluctuations is considered in this research. Sediment transport fluctuations were investigated in a set of 38 laboratory experiments carried out on a steep tilting flume, under several conditions of constant sediment and water discharge, for three different slopes (S=6.7%, 9.9%, and 13%). The impact of the diameter and spatial density of randomly placed boulders was studied for several flow conditions. Along with the sediment transport and bulk mean flow velocity, the boulder protrusion, boulder surface, and number of hydraulic jumps, which are indicators of the channel morphology, were measured regularly during the experiments. Periodic bedload pulses are clearly visible in the data collected during the experiments, along with well correlated fluctuations in the flow velocity and bed morphology parameters. Well-behaved cyclic oscillations in the auto-correlation and cross-correlation functions confirm the periodicity of the observed fluctuations and show that the durations of these cycles are similar, although not necessarily in phase. A detailed analysis of data time series and image acquired during the tests show a link between bedload pulses and different bed states, boulder protrusion, and surface grain size distributions. A feedback system exists among channel morphology, flow kinematics and sediment transport. A phase analysis for the observed variables, based on the identification of bedload cycles in the instantaneous signal, is performed. The link between the phases of bedload and each of the morphological parameters show a hysteretic path. The relation between the phase-averaged bedload and the phase-averaged flow velocity show a considerable lesser degree of hysteresis. Comparing the phase averaged bedload of the experiments, it is observed that the shape of bedload cycles is the same for all tested hydraulic conditions. The cycles present a long duration low sediment transport event and a shorter peak transport event. This indicates that long periods of sediment aggradations alternate with short erosion periods, even under constant hydraulic conditions. The bedload pulses may be characterized by their amplitude and period as a function of various boulder spatial densities and diameters. We show that for higher stream power, the fluctuations decrease, both in cycle duration and in amplitude. The presence of boulders increases the stream power needed to transport a given amount of sediment, thus decreasing fluctuations. KEY WORDS: Bedload fluctuations; Morphological changes; Sediment transport; Boulders; Steep channel.

Beneath the Surface: Understanding Patterns of Intra-Domain Orientational Order

NASA Astrophysics Data System (ADS)

Prasad, Ishan; Seo, Youngmi; Hall, Lisa; Grason, Gregory

Block copolymers (BCP) self assemble into a rich spectrum of ordered phases due to asymmetry in copolymer architecture. Despite extensive study of spatially-ordered composition patterns of BCP, knowledge of orientational order of chain segments that underlie these spatial patterns is evidently missing. We show using self consistent field (SCF) theory and coarse-grained molecular dynamics (MD) simulations that, even without explicit orientational interactions between segments, BCP exhibit generic patterns of intra-domain segment orientation, which vary both within a given morphology and from morphology to morphology. We find that segment alignment is usually both normal and parallel to the interface within different local regions of a BCP sub-domain. We describe principles that control relative strength and directionality of alignment in different morphologies and report a surprising yet generic emergence of biaxial segment order in morphologies with anisotropic curved interfaces, such as cylinders and gyroid phases. Finally, we focus our study on cholesteric textures that pervade mesochiral BCP morphologies, specifically alternating double gyroid (aDG) and helical cylinder (H*) phases, and analyze patterns of twisted (nematic and polar) segment order within these domains.

The influence of chemical structure on thermal properties and surface morphology of polyurethane materials.

PubMed

Brzeska, Joanna; Morawska, Magda; Heimowska, Aleksandra; Sikorska, Wanda; Wałach, Wojciech; Hercog, Anna; Kowalczuk, Marek; Rutkowska, Maria

2018-01-01

The surface morphology and thermal properties of polyurethanes can be correlated to their chemical composition. The hydrophilicity, surface morphology, and thermal properties of polyurethanes (differed in soft segments and in linear/cross-linked structure) were investigated. The influence of poly([ R , S ]-3-hydroxybutyrate) presence in soft segments and blending of polyurethane with polylactide on surface topography were also estimated. The linear polyurethanes (partially crystalline) had the granular surface, whereas the surface of cross-linked polyurethanes (almost amorphous) was smooth. Round aggregates of polylactide un-uniformly distributed in matrix of polyurethane were clearly visible. It was concluded that some modification of soft segment (by mixing of poly([ R , S ]-3-hydroxybutyrate) with different polydiols and polytriol) and blending of polyurethanes with small amount of polylactide influence on crystallinity and surface topography of obtained polyurethanes.

The effect of low energy helium ion irradiation on tungsten-tantalum (W-Ta) alloys under fusion relevant conditions

NASA Astrophysics Data System (ADS)

Gonderman, S.; Tripathi, J. K.; Novakowski, T. J.; Sizyuk, T.; Hassanein, A.

2017-08-01

Currently, tungsten remains the best candidate for plasma-facing components (PFCs) for future fusion devices because of its high melting point, low erosion, and strong mechanical properties. However, continued investigation has shown tungsten to undergo severe morphology changes under fusion-like conditions. These results motivate the study of innovative PFC materials which are resistant to surface morphology evolution. The goal of this work is to examine tungsten-tantalum (W-Ta) alloys, a potential PFC material, and their response to low energy helium ion irradiation. Specifically, W-Ta samples are exposed to 100 eV helium irradiations with a flux of 1.15 × 1021 ions m-2 s-1, at 873 K, 1023 K, and 1173 K for 1 h duration. Scanning electron microscopy (SEM) reveals significant changes in surface deterioration due to helium ion irradiation as a function of both temperature and tantalum concentration in W-Ta samples. X-Ray Diffraction (XRD) studies show a slight lattice parameter expansion in W-Ta alloy samples compared to pure W samples. The observed lattice parameter expansion in W-Ta alloy samples (proportional to increasing Ta wt.% concentrations) reflect significant differences observed in the evolution of surface morphology, i.e., fuzz development processes for both increasing Ta wt.% concentration and target temperature. These results suggest a correlation between the observed morphology differences and the induced crystal structure change caused by the presence of tantalum. Shifts in the XRD peaks before and after 100 eV helium irradiation with a flux of 1.15 × 1021 ions m-2 s-1, 1023 K, for 1 h showed a significant difference in the magnitude of the shift. This has suggested a possible link between the atomic spacing of the material and the accumulated damage. Ongoing research is needed on W-Ta alloys and other innovative materials for their application as irradiation resistant materials in future fusion or irradiation environments.

Nanocomposite film prepared by depositing xylan on cellulose nanowhiskers matrix

Treesearch

Qining Sun; Anurag Mandalika; Thomas Elder; Sandeep S. Nair; Xianzhi Meng; Fang Huang; Art J. Ragauskas

2014-01-01

Novel bionanocomposite films have been prepared by depositing xylan onto cellulose nanowhiskers through a pH adjustment. Analysis of strength properties, water vapour transmission, transparency, surface morphology and thermal decomposition showed the enhancement of film performance. This provides a new green route to the utilization of biomass for sustainable...

Surface-potential undulation of Alq3 thin films prepared on ITO, Au, and n-Si.

PubMed

Ozasa, Kazunari; Ito, Hiromi; Maeda, Mizuo; Hara, Masahiko

2012-01-01

The surface potential (SP) morphology on thin films of tris(8-hydroxyquinolinato) aluminum (Alq3) was investigated with Kelvin probe force microscopy. Thin Alq3 films of 100 nm were prepared on ITO/glass substrates, Au/mica substrates, and n-Si substrates. Cloud-like morphologies of the SP undulation with 200-400 nm in lateral size were observed for all three types of the substrates. New larger peaks were observed in the cloud-like morphologies when the surfaces were exposed shortly to a light, while the SP average was reduced monotonically. The nonuniform distribution of charged traps and mobility was deduced from the SP undulation morphology and its photoexposure dependences.

The fine structure of the stomach mucosa of the Llama (Llama guanacoe). II. The fundic region of the hind stomach.

PubMed

Luciano, L; Reale, E; von Engelhardt, W

1980-01-01

The epithelium of the fundic region mucosa of the hind stomach in the Llama guanacoe has been studied using morphological and histochemical methods. Morphology suggests that solute and water absorption may occur in the epithelium of the surface and of the foveolae, although this absorption can not be estimated because of the extensive secretion of the gastric glands. The same cells of the surface and foveolar epithelium show numerous secretory granules. The glands reveal neck cells, chief cells, a large number of oxyntic cells, four types of endocrine cells (A-like, ECL, D and EC), brush cells and wandering cells. PAS and Alcian blue reactions for light microscopy suggest a secretion of neutral and acidic mucosubstances in the surface and foveolar epithelium, of neutral mucosubstances only in the neck cells. Periodic acid-thiocarbohydrazide silver proteinate (PA-TCH-SP) reaction for electron microscopy confirms the presence of neutral mucosubstances within the secretory granules of the surface, foveolar and neck epithelial cells. In all these cells, the reaction product is also evident within sacculi and vesicles of the maturing surface of the Golgi apparatus. A positive PA-TCH-SP reaction also occurs on the membrane (and not on the contents) of the Golgi apparatus (maturing surface) and of the secretory granules of the chief cells as well as on the membrane of the Golgi apparatus and of apical vesicles and tubules of the oxyntic cells. In addition, silver granules slightly enhance the electron desity of the contents of the secretory granules in the endocrine cells. Morphological and histochemical findings are discussed and compared with results described by others for monogastric mammals.

Effects of pH values of hydrogen peroxide bleaching agents on enamel surface properties.

PubMed

Xu, B; Li, Q; Wang, Y

2011-01-01

This study investigated the influence of pH values of bleaching agents on the properties of the enamel surface. Sixty freshly extracted premolars were embedded in epoxy resin and mesiodistally sectioned through the buccal aspect into two parts. The sectioned slabs were distributed among six groups (n=10) and treated using different solutions. Group HCl was treated with HCl solution (pH=3.0) and served as a positive control. Group DW, stored in distilled water (pH=7.0), served as a negative control. Four treatment groups were treated using 30% hydrogen peroxide solutions with different pH values: group HP3 (pH=3.0), group HP5 (pH=5.0), group HP7 (pH=7.0), and group HP8 (pH=8.0). The buccal slabs were subjected to spectrophotometric evaluations. Scanning electron microscopy investigation and Micro-Raman spectroscopy were used to evaluate enamel surface morphological and chemical composition alterations. pH value has a significant influence on the color changes after bleaching (p<0.001). Tukey's multiple comparisons revealed that the order of color changes was HP8, HP7>HP5, HP3>HCl>DW. No obvious morphological alterations were detected on the enamel surface in groups DW, HP7, and HP8. The enamel surface of groups HCl and HP3 showed significant alterations with an erosion appearance. No obvious chemical composition changes were detected with respect to Micro-Raman analysis. Within the limitations of this study, it was concluded that no obvious morphological or chemical composition alterations of enamel surface were detected in the neutral or alkaline bleaching solutions. Bleaching solutions with lower pH values could result in more significant erosion of enamel, which represented a slight whitening effect.

Ground-based LiDAR Measurements of Actively Inflating Pahoehoe Flows, Kilauea Volcano, Hawaii: Implications for Emplacement of Basaltic Units on Mars

NASA Astrophysics Data System (ADS)

Byrnes, J. M.; Finnegan, D. C.; Nicoll, K.; Anderson, S. W.

2007-05-01

Remote sensing datasets enable planetary volcanologists to extract information regarding eruption processes. Long-lived effusive eruptions at sites such as Kilauea Volcano (HI) provide opportunities to collect rich observational data sets, including detailed measurements of topography and extrusion rates, that allow comparisons between lava flow surface morphologies and emplacement conditions for use in interpreting similar morphological features associated with planetary lava flows. On Mars, the emplacement of basaltic lava flows is a volumetrically and spatially important process, creating both large-scale and small-scale surface morphologies. On Earth, low effusion rate eruptions on relatively horizontal slopes tend to create inflated lava flows that display hummocky topography. To better understand the processes involved in creating observed surface characteristics, we repeatedly measured the surface topography of an actively flowing and inflating basaltic unit within the Pu'u O'o flow field over a 5-day period. We used a ground-based laser-scanner (LiDAR) system that provided vertical and horizontal accuracies of 4 mm. Comparing DEMs from repeated laser scans yielded the magnitudes and styles of constructional processes, allowing us to quantify the relationship between pre- and post-emplacement surface topography. Our study site (roughly 200 m x 200 m) experienced about 5 m of vertical inflation over a 3 day period and created a new hummocky surface containing several tumuli. The temporal and spatial patterns of inflation were complex and showed no obvious relationship with underlying topography. High-precision morphometric measurements acquired using ground-based LiDAR affords us the opportunity to capture the essential boundary conditions necessary for evaluating and comparing high-resolution planetary data sets, such as those acquired by the MOC, HRSC, and HiRISE instruments.

Cortical morphology development in patients with 22q11.2 deletion syndrome at ultra-high risk of psychosis.

PubMed

Padula, Maria Carmela; Schaer, Marie; Armando, Marco; Sandini, Corrado; Zöller, Daniela; Scariati, Elisa; Schneider, Maude; Eliez, Stephan

2018-01-17

Patients with 22q11.2 deletion syndrome (22q11DS) present a high risk of developing psychosis. While clinical and cognitive predictors for the conversion towards a full-blown psychotic disorder are well defined and largely used in practice, neural biomarkers do not yet exist. However, a number of investigations indicated an association between abnormalities in cortical morphology and higher symptoms severities in patients with 22q11DS. Nevertheless, few studies included homogeneous groups of patients differing in their psychotic symptoms profile. In this study, we included 22 patients meeting the criteria for an ultra-high-risk (UHR) psychotic state and 22 age-, gender- and IQ-matched non-UHR patients. Measures of cortical morphology, including cortical thickness, volume, surface area and gyrification, were compared between the two groups using mass-univariate and multivariate comparisons. Furthermore, the development of these measures was tested in the two groups using a mixed-model approach. Our results showed differences in cortical volume and surface area in UHR patients compared with non-UHR. In particular, we found a positive association between surface area and the rate of change of global functioning, suggesting that higher surface area is predictive of improved functioning with age. We also observed accelerated cortical thinning during adolescence in UHR patients with 22q11DS. These results, although preliminary, suggest that alterations in cortical volume and surface area as well as altered development of cortical thickness may be associated to a greater probability to develop psychosis in 22q11DS.

Patterns of morphological variation in enamel–dentin junction and outer enamel surface of human molars

PubMed Central

Morita, Wataru; Yano, Wataru; Nagaoka, Tomohito; Abe, Mikiko; Ohshima, Hayato; Nakatsukasa, Masato

2014-01-01

Tooth crown patterning is governed by the growth and folding of the inner enamel epithelium (IEE) and the following enamel deposition forms outer enamel surface (OES). We hypothesized that overall dental crown shape and covariation structure are determined by processes that configurate shape at the enamel–dentine junction (EDJ), the developmental vestige of IEE. This this hypothesis was tested by comparing patterns of morphological variation between EDJ and OES in human permanent maxillary first molar (UM1) and deciduous second molar (um2). Using geometric morphometric methods, we described morphological variation and covariation between EDJ and OES, and evaluated the strength of two components of phenotypic variability, canalization and morphological integration, in addition to the relevant evolutionary flexibility, i.e. the ability to respond to selective pressure. The strength of covariation between EDJ and OES was greater in um2 than in UM1, and the way that multiple traits covary between EDJ and OES was different between these teeth. The variability analyses showed that EDJ had less shape variation and a higher level of morphological integration than OES, which indicated that canalization and morphological integration acted as developmental constraints. These tendencies were greater in UM1 than in um2. On the other hand, EDJ and OES had a comparable level of evolvability in these teeth. Amelogenesis could play a significant role in tooth shape and covariation structure, and its influence was not constant among teeth, which may be responsible for the differences in the rate and/or period of enamel formation. PMID:24689536

Complex and oriented ZnO nanostructures.

PubMed

Tian, Zhengrong R; Voigt, James A; Liu, Jun; McKenzie, Bonnie; McDermott, Matthew J; Rodriguez, Mark A; Konishi, Hiromi; Xu, Huifang

2003-12-01

Extended and oriented nanostructures are desirable for many applications, but direct fabrication of complex nanostructures with controlled crystalline morphology, orientation and surface architectures remains a significant challenge. Here we report a low-temperature, environmentally benign, solution-based approach for the preparation of complex and oriented ZnO nanostructures, and the systematic modification of their crystal morphology. Using controlled seeded growth and citrate anions that selectively adsorb on ZnO basal planes as the structure-directing agent, we prepared large arrays of oriented ZnO nanorods with controlled aspect ratios, complex film morphologies made of oriented nanocolumns and nanoplates (remarkably similar to biomineral structures in red abalone shells) and complex bilayers showing in situ column-to-rod morphological transitions. The advantages of some of these ZnO structures for photocatalytic decompositions of volatile organic compounds were demonstrated. The novel ZnO nanostructures are expected to have great potential for sensing, catalysis, optical emission, piezoelectric transduction, and actuations.

Buckling of paramagnetic chains in soft gels

NASA Astrophysics Data System (ADS)

Huang, Shilin; Pessot, Giorgio; Cremer, Peet; Weeber, Rudolf; Holm, Christian; Nowak, Johannes; Odenbach, Stefan; Menzel, Andreas M.; Auernhammer, Günter K.

We study the magneto-elastic coupling behavior of paramagnetic chains in soft polymer gels exposed to external magnetic fields. To this end, a laser scanning confocal microscope is used to observe the morphology of the paramagnetic chains together with the deformation field of the surrounding gel network. The paramagnetic chains in soft polymer gels show rich morphological shape changes under oblique magnetic fields, in particular a pronounced buckling deformation. The details of the resulting morphological shapes depend on the length of the chain, the strength of the external magnetic field, and the modulus of the gel. Based on the observation that the magnetic chains are strongly coupled to the surrounding polymer network, a simplified model is developed to describe their buckling behavior. A coarse-grained molecular dynamics simulation model featuring an increased matrix stiffness on the surfaces of the particles leads to morphologies in agreement with the experimentally observed buckling effects.

Effect of solvents on the optical and morphological properties of MEH-PPV: PC70BM nanocomposites

NASA Astrophysics Data System (ADS)

Mhamdi, Asya; Ltaief, Adnen; Bouazizi, Abdelaziz

2017-10-01

Focused on phase separation and morphologies of polymer poly [2-methoxy-5-(2'-ethyl) hexoxy-1,4-phenylenevinylene] (MEH-PPV) and [6,6]-phenylC71-butyric acid methyl ester (PC70BM) nanocomposite, we studied the effect of organic solvent on the optical and morphological properties of these blends. The MEH-PPV: PC70BM films was prepared using three different solvent; Tetrahydrofuran (THF), Chlorobenzene (CB) and Toluene. On the other hand, the effect of 1-8 octanedithiol additives is also studied with the same different solvents. These blend films are characterized by photoluminescence spectroscopy, UV-Vis absorption spectroscopy and atomic force microscopy (AFM). The photoluminescence results show that the THF solvent provide the better charge transfer. In a morphological view point, the phase segregation was clearly appearing by the addition of the additive on the surface of the blend films.

Evidences of early aqueous Mars: Implications on the origin of branched valleys in the Ius Chasma, Mars

NASA Astrophysics Data System (ADS)

Martha, Tapas R.; Jain, Nirmala; Vamshi, Gasiganti T.; Vinod Kumar, K.

2017-11-01

This study shows results of morphological and spectroscopic analyses of Ius Chasma and its southern branched valleys using Orbiter datasets such as Mars Reconnaissance Orbiter (MRO)-Compact Reconnaissance Imaging Spectrometer for Mars (CRISM), High Resolution Imaging Science Experiment (MRO-HiRISE) and digital terrain model (HRSC-DTM). Result of the spectral analysis reveals presence of hydrated minerals such as opal, nontronite and vermiculite in the floor and wall rock areas Ius Chasma indicating alteration of parent rock in an water rich environment of early Mars. Topographic gradient and morphological evidences such as V-shaped valleys with theatre shaped stubby channels, dendritic drainage and river piracy indicate that these valleys were initially developed by surface runoff due to episodic floods and further expanded due to groundwater sapping controlled by faults and fractures. Minerals formed by aqueous alteration during valley formation and their intricate association with different morphological domains suggest that surface runoff played a key role in the development of branched valleys south of Ius Chasma on Mars.

A novel copper/polydimethiylsiloxane nanocomposite for copper-containing intrauterine contraceptive devices.

PubMed

Xu, X X; Ding, M H; Zhang, J X; Zheng, W; Li, L; Zheng, Y F

2013-11-01

In this article, a novel composite of copper (Cu) nanoparticles and polydimethiylsiloxane (PDMS) has been prepared and investigated for the potential application in Cu-containing intrauterine device. The Cu/PDMS composite with various mass fraction of Cu nanoparticles was fabricated via the hot vulcanizing process. The chemical structures and surface morphologies of the Cu/PDMS composites were characterized confirming the physical interaction between Cu nanoparticles and PDMS. The surface morphology observation using scanning electron microscope and atomic force microscope showed the agglomeration of Cu nanoparticles in PDMS matrix and the distribution of the agglomerations was more uniform with increased amount of Cu nanoparticles. The cupric ion release behaviors of the Cu/PDMS composites with different amounts of Cu nanoparticles were investigated in simulated uterine fluid at 37°C for 150 days. The corrosion morphologies of the Cu/PDMS composites were also characterized. Both the burst release rate of the cupric ion in the first few days and the steady release rate after 30-day immersion were improved. The cytotoxicity test has been done for the Cu/PDMS composites. Copyright © 2013 Wiley Periodicals, Inc.