Scale-free networks of the earth’s surface

NASA Astrophysics Data System (ADS)

Liu, Gang; He, Jing; Luo, Kaitian; Gao, Peichao; Ma, Lei

2016-06-01

Studying the structure of real complex systems is of paramount importance in science and engineering. Despite our understanding of lots of real systems, we hardly cognize our unique living environment — the earth. The structural complexity of the earth’s surface is, however, still unknown in detail. Here, we define the modeling of graph topology for the earth’s surface, using the satellite images of the earth’s surface under different spatial resolutions derived from Google Earth. We find that the graph topologies of the earth’s surface are scale-free networks regardless of the spatial resolutions. For different spatial resolutions, the exponents of power-law distributions and the modularity are both quite different; however, the average clustering coefficient is approximately equal to a constant. We explore the morphology study of the earth’s surface, which enables a comprehensive understanding of the morphological feature of the earth’s surface.

Morphological Properties of Siloxane-Hydrogel Contact Lens Surfaces.

PubMed

Stach, Sebastian; Ţălu, Ştefan; Trabattoni, Silvia; Tavazzi, Silvia; Głuchaczka, Alicja; Siek, Patrycja; Zając, Joanna; Giovanzana, Stefano

2017-04-01

The aim of this study was to quantitatively characterize the micromorphology of contact lens (CL) surfaces using atomic force microscopy (AFM) and multifractal analysis. AFM and multifractal analysis were used to characterize the topography of new and worn siloxane-hydrogel CLs made of Filcon V (I FDA group). CL surface roughness was studied by AFM in intermittent-contact mode, in air, on square areas of 25 and 100 μm 2 , by using a Nanoscope V MultiMode (Bruker). Detailed surface characterization of the surface topography was obtained using statistical parameters of 3-D (three-dimensional) surface roughness, in accordance with ISO 25178-2: 2012. Before wear, the surface was found to be characterized by out-of-plane and sharp structures, whilst after a wear of 8 h, two typical morphologies were observed. One morphology (sharp type) has a similar aspect as the unworn CLs and the other morphology (smooth type) is characterized by troughs and bumpy structures. The analysis of the AFM images revealed a multifractal geometry. The generalized dimension D q and the singularity spectrum f(α) provided quantitative values that characterize the local scale properties of CL surface geometry at nanometer scale. Surface statistical parameters deduced by multifractal analysis can be used to assess the CL micromorphology and can be used by manufacturers in developing CLs with improved surface characteristics. These parameters can also be used in understanding the tribological interactions of the back surface of the CL with the corneal surface and the front surface of the CL with the under-surface of the eyelid (friction, wear, and micro-elastohydrodynamic lubrication at a nanometer scale).

Scanning electron microscope fractography of induced fatigue-damaged saline breast implants.

PubMed

Brandon, H J; Jerina, K L; Savoy, T L; Wolf, C J

2006-01-01

Breast implant strength and durability is presently an important topic in biomaterials science. Research studies are being conducted to determine the mechanisms and rates of failure in order to assess the in vivo performance of breast implants. Fatigue life is a measure of breast implant durability since fatigue failure is a potential in vivo failure mechanism. This study describes the characterization of the fracture surface morphology of breast implant shell regions that have failed due to cyclic fatigue. Saline breast implants were fatigue tested to failure using a laboratory apparatus in which flat plates cyclically compressed the implants. The implants were unimplanted control devices of both textured and smooth saline implants. The failure surfaces of the fatigued shells were examined using scanning electron microscopy (SEM). The morphological features of the failure surfaces are described for implants with short and long fatigue lifetimes. The details of both the inside and outside surfaces of the shell at the failure location are described. Two different modes of failure were observed in both the textured and smooth shells. These modes depend on the magnitude of the cyclic load and corresponding number of fatigue cycles at failure. The first mode is a tear in the shell of about 18 mm in length, and the second mode is a pinhole approximately 1 mm in diameter. Details of the surface morphology for these two types of failure modes and shell thickness data are presented herein. There was no significant change in the crosslink density of the shell as a result of fatigue.

Strike-Slip Faulting Processes on Ganymede: Global Morphological Mapping and Structural Interpretation of Grooved and Transitional Terrains

NASA Astrophysics Data System (ADS)

Burkhard, L. M.; Cameron, M. E.; Smith-Konter, B. R.; Seifert, F.; Pappalardo, R. T.; Collins, G. C.

2015-12-01

Ganymede's fractured surface reveals many large-scale, morphologically distinct regions of inferred distributed shear and strike-slip faulting that may be important to the structural development of its surface and in the transition from dark to light (grooved) materials. To better understand the role of strike-slip tectonism in shaping Ganymede's complex icy surface, we perform a detailed mapping of key examples of strike-slip morphologies (i.e., en echelon structures, strike-slip duplexes, laterally offset pre-existing features, and possible strained craters) from Galileo and Voyager images. We focus on complex structures associated with grooved terrain (e.g. Nun Sulcus, Dardanus Sulcus, Tiamat Sulcus, and Arbela Sulcus) and terrains transitional from dark to light terrain (e.g. the boundary between Nippur Sulcus and Marius Regio, including Byblus Sulcus and Philus Sulcus). Detailed structural interpretations suggest strong evidence of strike-slip faulting in some regions (i.e., Nun and Dardanus Sulcus); however, further investigation of additional strike-slip structures is required of less convincing regions (i.e., Byblus Sulcus). Where applicable, these results are synthesized into a global database representing an inferred sense of shear for many of Ganymede's fractures. Moreover, when combined with existing observations of extensional features, these results help to narrow down the range of possible principal stress directions that could have acted at the regional or global scale to produce grooved terrain on Ganymede.

Atomic-scale analysis of deposition and characterization of a-Si:H thin films grown from SiH radical precursor

NASA Astrophysics Data System (ADS)

Sriraman, Saravanapriyan; Aydil, Eray S.; Maroudas, Dimitrios

2002-07-01

Growth of hydrogenated amorphous silicon films (a-Si:H) on an initial H-terminated Si(001)(2 x1) substrate at T=500 K was studied through molecular-dynamics (MD) simulations of repeated impingement of SiH radicals to elucidate the effects of reactive minority species on the structural quality of the deposited films. The important reactions contributing to film growth were identified through detailed visualization of radical-surface interaction trajectories. These reactions include (i) insertion of SiH into Si-Si bonds, (ii) adsorption onto surface dangling bonds, (iii) surface H abstraction by impinging SiH radicals through an Eley-Rideal mechanism, (iv) surface adsorption by penetration into subsurface layers or dissociation leading to interstitial atomic hydrogen, (v) desorption of interstitial hydrogen into the gas phase, (vi) formation of higher surface hydrides through the exchange of hydrogen, and (vii) dangling-bond-mediated dissociation of surface hydrides into monohydrides. The MD simulations of a-Si:H film growth predict an overall surface reaction probability of 95% for the SiH radical that is in good agreement with experimental measurements. Structural and chemical characterization of the deposited films was based on the detailed analysis of evolution of the films' structure, surface morphology and roughness, surface reactivity, and surface composition. The analysis revealed that the deposited films exhibit high dangling bond densities and rough surface morphologies. In addition, the films are abundant in voids and columnar structures that are detrimental to producing device-quality a-Si:H thin films.

High resolution urban morphology data for urban wind flow modeling

NASA Astrophysics Data System (ADS)

Cionco, Ronald M.; Ellefsen, Richard

The application of urban forestry methods and technologies to a number of practical problems can be further enhanced by the use and incorporation of localized, high resolution wind and temperature fields into their analysis methods. The numerical simulation of these micrometeorological fields will represent the interactions and influences of urban structures, vegetation elements, and variable terrain as an integral part of the dynamics of an urban domain. Detailed information of the natural and man-made components that make up the urban area is needed to more realistically model meteorological fields in urban domains. Simulating high resolution wind and temperatures over and through an urban domain utilizing detailed morphology data can also define and quantify local areas where urban forestry applications can contribute to better solutions. Applications such as the benefits of planting trees for shade purposes can be considered, planned, and evaluated for their impact on conserving energy and cooling costs as well as the possible reconfiguration or removal of trees and other barriers for improved airflow ventilation and similar processes. To generate these fields, a wind model must be provided, as a minimum, the location, type, height, structural silhouette, and surface roughness of these components, in order to account for the presence and effects of these land morphology features upon the ambient airflow. The morphology of Sacramento, CA has been characterized and quantified in considerable detail primarily for wind flow modeling, simulation, and analyses, but can also be used for improved meteorological analyses, urban forestry, urban planning, and other urban related activities. Morphology methods previously developed by Ellefsen are applied to the Sacramento scenario with a high resolution grid of 100 m × 100 m. The Urban Morphology Scheme defines Urban Terrain Zones (UTZ) according to how buildings and other urban elements are structured and placed with respect to each other. The urban elements within the 100 m × 100 m cells (one hectare) are further described and digitized as building height, building footprint (in percent), reflectivity of its roof, pitched roof or flat, building's long axis orientation, footprint of impervious surface and its reflectivity, footprint of canopy elements, footprint of woodlots, footprint of grass area, and footprint of water surface. A variety of maps, satellite images, low level aerial photographs, and street level photographs are the raw data used to quantify these urban properties. The final digitized morphology database resides in a spreadsheet ready for use on ordinary personal computers.

Foam morphology, frustration and topological defects in a Negatively curved Hele-Shaw geometry

NASA Astrophysics Data System (ADS)

Mughal, Adil; Schroeder-Turk, Gerd; Evans, Myfanwy

2014-03-01

We present preliminary simulations of foams and single bubbles confined in a narrow gap between parallel surfaces. Unlike previous work, in which the bounding surfaces are flat (the so called Hele-Shaw geometry), we consider surfaces with non-vanishing Gaussian curvature. We demonstrate that the curvature of the bounding surfaces induce a geometric frustration in the preferred order of the foam. This frustration can be relieved by the introduction of topological defects (disclinations, dislocations and complex scar arrangements). We give a detailed analysis of these defects for foams confined in curved Hele-Shaw cells and compare our results with exotic honeycombs, built by bees on surfaces of varying Gaussian curvature. Our simulations, while encompassing surfaces of constant Gaussian curvature (such as the sphere and the cylinder), focus on surfaces with negative Gaussian curvature and in particular triply periodic minimal surfaces (such as the Schwarz P-surface and the Schoen's Gyroid surface). We use the results from a sphere-packing algorithm to generate a Voronoi partition that forms the basis of a Surface Evolver simulation, which yields a realistic foam morphology.

To attach or not to attach? The effect of carrier surface morphology and topography on attachment of phoretic deutonymphs of Uropoda orbicularis (Acari).

PubMed

Bajerlein, Daria; Adamski, Zbigniew; Kacalak, Wojciech; Tandecka, Katarzyna; Wiesner, Maciej; Jurga, Stefan

2016-08-01

Previous studies on preferences of phoretic deutonymphs of Uropodina for attachment sites have shown that they frequently select smooth and hydrophobic surfaces. The aim of our study was to provide the detailed morphological and topographical characteristics of beetle body surfaces to which deutonymphs frequently attach and to verify how the presence of setae and surface sculpture affects deutonymph attachment. The study was conducted on Uropoda orbicularis (Müller, 1776) and its common beetle carriers: Aphodius prodromus (Brahm, 1790), Aphodius fimetarius (Linnaeus, 1758), Onthophagus nuchicornis (Linnaeus, 1758) and Margarinotus carbonarius (Hoffmann, 1803). Morphology and topography of elytra, femora, propygidia and pygidia of beetles were analysed mainly using SEM methods supported with CLSM and AFM techniques. The hypothesis that deutonymphs may attach to surfaces covered with setae, if seta density is low enough not to disturb mite movement, was tested. The study revealed that deutonymphs attach to surfaces of various types as follows: (i) smooth, (ii) hairy, i.e., covered with setae, (iii) flat and (iv) sculptured. Smooth body parts and body parts covered with setae of low density were most frequently and intensively occupied with deutonymphs. Surfaces of high seta density were avoided by mites. Within elytra of Aphodius beetles, deutonymphs definitely preferred flat surfaces of elytral intervals. On the contrary, densely punctuated propygidium and pygidium in M. carbonarius were heavily infested with deutonymphs. We conclude that carrier surface morphology and topography are important for Uropodina deutonymph attachment, but these two factors cannot fully explain the observed relation.

To attach or not to attach? The effect of carrier surface morphology and topography on attachment of phoretic deutonymphs of Uropoda orbicularis (Acari)

NASA Astrophysics Data System (ADS)

Bajerlein, Daria; Adamski, Zbigniew; Kacalak, Wojciech; Tandecka, Katarzyna; Wiesner, Maciej; Jurga, Stefan

2016-08-01

Previous studies on preferences of phoretic deutonymphs of Uropodina for attachment sites have shown that they frequently select smooth and hydrophobic surfaces. The aim of our study was to provide the detailed morphological and topographical characteristics of beetle body surfaces to which deutonymphs frequently attach and to verify how the presence of setae and surface sculpture affects deutonymph attachment. The study was conducted on Uropoda orbicularis (Müller, 1776) and its common beetle carriers: Aphodius prodromus (Brahm, 1790), Aphodius fimetarius (Linnaeus, 1758), Onthophagus nuchicornis (Linnaeus, 1758) and Margarinotus carbonarius (Hoffmann, 1803). Morphology and topography of elytra, femora, propygidia and pygidia of beetles were analysed mainly using SEM methods supported with CLSM and AFM techniques. The hypothesis that deutonymphs may attach to surfaces covered with setae, if seta density is low enough not to disturb mite movement, was tested. The study revealed that deutonymphs attach to surfaces of various types as follows: (i) smooth, (ii) hairy, i.e., covered with setae, (iii) flat and (iv) sculptured. Smooth body parts and body parts covered with setae of low density were most frequently and intensively occupied with deutonymphs. Surfaces of high seta density were avoided by mites. Within elytra of Aphodius beetles, deutonymphs definitely preferred flat surfaces of elytral intervals. On the contrary, densely punctuated propygidium and pygidium in M. carbonarius were heavily infested with deutonymphs. We conclude that carrier surface morphology and topography are important for Uropodina deutonymph attachment, but these two factors cannot fully explain the observed relation.

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.

Geomorphological Mapping on the Southern Hemisphere of Comet 67P/Churyumov-Gerasimenko

NASA Astrophysics Data System (ADS)

Lee, Jui-Chi; Massironi, Matteo; Giacomini, Lorenza; Ip, Wing-Huen; El-Maarry, Mohamed R.

2016-04-01

Since its rendezvous with comet 67P/Churyumov-Gerasimenko on the sixth of August, 2014, the Rosetta spacecraft has carried out close-up observations of the nucleus and coma of this Jupiter family comet. The OSIRIS, the Scientific Imaging Camera System onboard the Rosetta spacecraft, which consists of a narrow-angle and wide-angle camera (NAC and WAC), has made detailed investigations of the physical properties and surface morphology of the comet. From May 2015, the southern hemisphere of the comet became visible and the adaptical resolution was high enough for us to do a detailed analysis of the surface. Previous work shows that the fine particle deposits are the most extensive geomorphological unit in the northern hemisphere. On the contrary, southern hemisphere is dominated by rocky-like stratified terrain. The southern hemisphere of the nucleus surface reveals quite different morphologies from the northern hemisphere. This could be linked to the different insolation condition between northern and southern hemisphere. As a result, surface geological processes could operate with a diverse intensity on the different sides of the comet nucleus. In this work, we provide the geomorphological maps of the southern hemisphere with linear features and geological units identified. The geomorphological maps described in this study allow us to understand the processes and the origin of the comet.

Morphological analysis of hummocks in debris avalanche deposits using UAS-derived high-definition topographic data

NASA Astrophysics Data System (ADS)

Hayakawa, Yuichi S.; Obanawa, Hiroyuki; Yoshida, Hidetsugu; Naruhashi, Ryutaro; Okumura, Koji; Zaiki, Masumi

2016-04-01

Debris avalanche caused by sector collapse of a volcanic mountain often forms depositional landforms with characteristic surface morphology comprising hummocks. Geomorphological and sedimentological analyses of debris avalanche deposits (DAD) at the northeastern face of Mt. Erciyes in central Turkey have been performed to investigate the mechanisms and processes of the debris avalanche. The morphometry of hummocks provides an opportunity to examine the volumetric and kinematic characteristics of the DAD. Although the exact age has been unknown, the sector collapse of this DAD was supposed to have occurred in the late Pleistocene (sometime during 90-20 ka), and subsequent sediment supply from the DAD could have affected ancient human activities in the downstream basin areas. In order to measure detailed surface morphology and depositional structures of the DAD, we apply structure-from-motion multi-view stereo (SfM-MVS) photogrammetry using unmanned aerial system (UAS) and a handheld camera. The UAS, including small unmanned aerial vehicle (sUAV) and a digital camera, provides low-altitude aerial photographs to capture surface morphology for an area of several square kilometers. A high-resolution topographic data, as well as an orthorectified image, of the hummocks were then obtained from the digital elevation model (DEM), and the geometric features of the hummocks were examined. A handheld camera is also used to obtain photographs of outcrop face of the DAD along a road to support the seimentological investigation. The three-dimensional topographic models of the outcrop, with a panoramic orthorectified image projected on a vertical plane, were obtained. This data enables to effectively describe sedimentological structure of the hummock in DAD. The detailed map of the DAD is also further examined with a regional geomorphological map to be compared with other geomorphological features including fluvial valleys, terraces, lakes and active faults.

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.

Laser surface treatment of polyamide and NiTi alloy and the effects on mesenchymal stem cell response

NASA Astrophysics Data System (ADS)

Waugh, D. G.; Lawrence, J.; Shukla, P.; Chan, C.; Hussain, I.; Man, H. C.; Smith, G. C.

2015-07-01

Mesenchymal stem cells (MSCs) are known to play important roles in development, post-natal growth, repair, and regeneration of mesenchymal tissues. What is more, surface treatments are widely reported to affect the biomimetic nature of materials. This paper will detail, discuss and compare laser surface treatment of polyamide (Polyamide 6,6), using a 60 W CO2 laser, and NiTi alloy, using a 100 W fiber laser, and the effects of these treatments on mesenchymal stem cell response. The surface morphology and composition of the polyamide and NiTi alloy were studied by scanning electron microscopy (SEM) and X-ray photoemission spectroscopy (XPS), respectively. MSC cell morphology cell counting and viability measurements were done by employing a haemocytometer and MTT colorimetric assay. The success of enhanced adhesion and spreading of the MSCs on each of the laser surface treated samples, when compared to as-received samples, is evidenced in this work.

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.

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.

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

Oohama, N.; Okamura, S.; Fukugita, M.

A bulge-disk decomposition is made for 737 spiral and lenticular galaxies drawn from a Sloan Digital Sky Survey galaxy sample for which morphological types are estimated. We carry out the bulge-disk decomposition using the growth curve fitting method. It is found that bulge properties, effective radius, effective surface brightness, and also absolute magnitude, change systematically with the morphological sequence; from early to late types, the size becomes somewhat larger, and surface brightness and luminosity fainter. In contrast, disks are nearly universal, their properties remaining similar among disk galaxies irrespective of detailed morphologies from S0 to Sc. While these tendencies weremore » often discussed in previous studies, the present study confirms them based on a large homogeneous magnitude-limited field galaxy sample with morphological types estimated. The systematic change of bulge-to-total luminosity ratio, B/T, along the morphological sequence is therefore not caused by disks but mostly by bulges. It is also shown that elliptical galaxies and bulges of spiral galaxies are unlikely to be in a single sequence. We infer the stellar mass density (in units of the critical mass density) to be OMEGA = 0.0021 for spheroids, i.e., elliptical galaxies plus bulges of spiral galaxies, and OMEGA = 0.00081 for disks.« less

Structural, optical and field emission properties of urchin-shaped ZnO nanostructures.

PubMed

Al-Heniti, Saleh; Umar, Ahmad

2013-01-01

In this work, well-crystallized urchin-shaped ZnO structures were synthesized on silicon substrate by simple non-catalytic thermal evaporation process by using metallic zinc powder in the presence of oxygen as source materials for zinc and oxygen, respectively. The synthesized ZnO structures were characterized in detail in terms of their morphological, structural, optical and field emission properties. The detailed morphological investigations revealed that the synthesized structures possess urchin-shape and grown in high-density over the substrate surface. The detailed structural and optical characterizations revealed that the synthesized urchin-shaped ZnO structures are well-crystallized and exhibiting good optical properties. The field emission analysis for urchin-shaped ZnO structures exhibits a turn-on field of 4.6 V/microm. The emission current density reached to 0.056 mA/cm2 at an applied electrical field of 6.4 V/microm and shows no saturation. The calculated field enhancement factor 'beta', from the F-N plot, was found to be approximately 2.2 x 10(3).

Morphological changes in textile fibres exposed to environmental stresses: atomic force microscopic examination.

PubMed

Canetta, Elisabetta; Montiel, Kimberley; Adya, Ashok K

2009-10-30

The ability of the atomic force microscope (AFM) to investigate the nanoscopic morphological changes in the surfaces of fabrics was examined for the first time. This study focussed on two natural (cotton and wool), and a regenerated cellulose (viscose) textile fibres exposed to various environmental stresses for different lengths of times. Analyses of the AFM images allowed us to measure quantitatively the surface texture parameters of the environmentally stressed fabrics as a function of the exposure time. It was also possible to visualise at the nanoscale the finest details of the surfaces of three weathered fabrics and clearly distinguish between the detrimental effects of the imposed environmental conditions. This study confirmed that the AFM could become a very powerful tool in forensic examination of textile fibres to provide significant fibre evidence due to its capability of distinguishing between different environmental exposures or forced damages to fibres.

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.

Collective evolution of submicron hillocks during the early stages of anisotropic alkaline wet chemical etching of Si(1 0 0) surfaces

NASA Astrophysics Data System (ADS)

Sana, P.; Vázquez, Luis; Cuerno, Rodolfo; Sarkar, Subhendu

2017-11-01

We address experimentally the large-scale dynamics of Si(1 0 0) surfaces during the initial stages of anisotropic wet (KOH) chemical etching, which are characterized through atomic force microscopy. These systems are known to lead to the formation of characteristic pyramids, or hillocks, of typical sizes in the nanometric/micrometer scales, thus with the potential for a large number of applications that can benefit from the nanotexturing of Si surfaces. The present pattern formation process is very strongly disordered in space. We assess the space correlations in such a type of rough surface and elucidate the existence of a complex and rich morphological evolution, featuring at least three different regimes in just 10 min of etching. Such a complex time behavior cannot be consistently explained within a single formalism for dynamic scaling. The pyramidal structure reveals itself as the basic morphological motif of the surface throughout the dynamics. A detailed analysis of the surface slope distribution with etching time reveals that the texturing process induced by the KOH etching is rather gradual and progressive, which accounts for the dynamic complexity. The various stages of the morphological evolution can be accurately reproduced by computer-generated surfaces composed by uncorrelated pyramidal structures. To reach such an agreement, the key parameters are the average pyramid size, which increases with etching time, its distribution and the surface coverage by the pyramidal structures.

Two new species and one new record of the genus Tylopilus (Boletaceae) from Indian Himalaya with morphological details and phylogenetic estimations

PubMed Central

Chakraborty, Dyutiparna; Vizzini, Alfredo; Das, Kanad

2018-01-01

Abstract Tylopilus himalayanus and T. pseudoballoui are described as new species from two Himalayan states (Sikkim and Uttarakhand) in India. Tylopilus himalayanus is characterised by a unique combination of features: reddish- or brownish-grey to purplish-grey then brown to reddish-brown or darker pileus, absence of olive or violet tinges on stipe surface, angular pores, stipe without reticulum or rarely with a faint reticulum restricted to the very apex, bitter taste of the context and positive macrochemical colour reaction of the stipe context with KOH (dark orange) and FeSO4 (dark green), medium sized (10.9–14.4 × 3.9–4.9 µm) basidiospores and occurrence under coniferous trees; T. pseudoballoui is distinguished by orange-yellow to brown-yellow sticky pileus, pale yellow pore surface with pinkish hues that turns pale to greyish-orange on bruising; angular pores, stipe concolorous to pileus with pruinose but never reticulate surface, ixocutis pattern of pileipellis and occurrence under broadleaf trees. Another species, T. neofelleus, which was reported earlier from China and Japan, was also collected from Sikkim and reported for the first time from India. All three species are described with morphological details and two-locus based (nrLSU and nrITS) phylogenetic data. PMID:29686503

Shaping skeletal growth by modular regulatory elements in the Bmp5 gene.

PubMed

Guenther, Catherine; Pantalena-Filho, Luiz; Kingsley, David M

2008-12-01

Cartilage and bone are formed into a remarkable range of shapes and sizes that underlie many anatomical adaptations to different lifestyles in vertebrates. Although the morphological blueprints for individual cartilage and bony structures must somehow be encoded in the genome, we currently know little about the detailed genomic mechanisms that direct precise growth patterns for particular bones. We have carried out large-scale enhancer surveys to identify the regulatory architecture controlling developmental expression of the mouse Bmp5 gene, which encodes a secreted signaling molecule required for normal morphology of specific skeletal features. Although Bmp5 is expressed in many skeletal precursors, different enhancers control expression in individual bones. Remarkably, we show here that different enhancers also exist for highly restricted spatial subdomains along the surface of individual skeletal structures, including ribs and nasal cartilages. Transgenic, null, and regulatory mutations confirm that these anatomy-specific sequences are sufficient to trigger local changes in skeletal morphology and are required for establishing normal growth rates on separate bone surfaces. Our findings suggest that individual bones are composite structures whose detailed growth patterns are built from many smaller lineage and gene expression domains. Individual enhancers in BMP genes provide a genomic mechanism for controlling precise growth domains in particular cartilages and bones, making it possible to separately regulate skeletal anatomy at highly specific locations in the body.

Material and morphology parameter sensitivity analysis in particulate composite materials

NASA Astrophysics Data System (ADS)

Zhang, Xiaoyu; Oskay, Caglar

2017-12-01

This manuscript presents a novel parameter sensitivity analysis framework for damage and failure modeling of particulate composite materials subjected to dynamic loading. The proposed framework employs global sensitivity analysis to study the variance in the failure response as a function of model parameters. In view of the computational complexity of performing thousands of detailed microstructural simulations to characterize sensitivities, Gaussian process (GP) surrogate modeling is incorporated into the framework. In order to capture the discontinuity in response surfaces, the GP models are integrated with a support vector machine classification algorithm that identifies the discontinuities within response surfaces. The proposed framework is employed to quantify variability and sensitivities in the failure response of polymer bonded particulate energetic materials under dynamic loads to material properties and morphological parameters that define the material microstructure. Particular emphasis is placed on the identification of sensitivity to interfaces between the polymer binder and the energetic particles. The proposed framework has been demonstrated to identify the most consequential material and morphological parameters under vibrational and impact loads.

Modification of the Surface Topography and Composition of Ultrafine and Coarse Grained Titanium by Chemical Etching.

PubMed

Nazarov, Denis V; Zemtsova, Elena G; Solokhin, Alexandr Yu; Valiev, Ruslan Z; Smirnov, Vladimir M

2017-01-13

In this study, we present the detailed investigation of the influence of the etching medium (acidic or basic Piranha solutions) and the etching time on the morphology and surface relief of ultrafine grained (UFG) and coarse grained (CG) titanium. The surface relief and morphology have been studied by means of scanning electron microscopy (SEM), atomic force microscopy (AFM), and the spectral ellipsometry. The composition of the samples has been determined by X-ray fluorescence analysis (XRF) and X-ray Photoelectron Spectroscopy (XPS). Significant difference in the etching behavior of UFG and CG titanium has been found. UFG titanium exhibits higher etching activity independently of the etching medium. Formed structures possess higher homogeneity. The variation of the etching medium and time leads to micro-, nano-, or hierarchical micro/nanostructures on the surface. Significant difference has been found between surface composition for UFG titanium etched in basic and acidic Piranha solution. Based on the experimental data, the possible reasons and mechanisms are considered for the formation of nano- and microstructures. The prospects of etched UFG titanium as the material for implants are discussed.

Modification of the Surface Topography and Composition of Ultrafine and Coarse Grained Titanium by Chemical Etching

PubMed Central

Nazarov, Denis V.; Zemtsova, Elena G.; Solokhin, Alexandr Yu.; Valiev, Ruslan Z.; Smirnov, Vladimir M.

2017-01-01

In this study, we present the detailed investigation of the influence of the etching medium (acidic or basic Piranha solutions) and the etching time on the morphology and surface relief of ultrafine grained (UFG) and coarse grained (CG) titanium. The surface relief and morphology have been studied by means of scanning electron microscopy (SEM), atomic force microscopy (AFM), and the spectral ellipsometry. The composition of the samples has been determined by X-ray fluorescence analysis (XRF) and X-ray Photoelectron Spectroscopy (XPS). Significant difference in the etching behavior of UFG and CG titanium has been found. UFG titanium exhibits higher etching activity independently of the etching medium. Formed structures possess higher homogeneity. The variation of the etching medium and time leads to micro-, nano-, or hierarchical micro/nanostructures on the surface. Significant difference has been found between surface composition for UFG titanium etched in basic and acidic Piranha solution. Based on the experimental data, the possible reasons and mechanisms are considered for the formation of nano- and microstructures. The prospects of etched UFG titanium as the material for implants are discussed. PMID:28336849

Plasma variables and tribological properties of coatings in low pressure (0.1 - 10.0 torr) plasma systems

NASA Technical Reports Server (NTRS)

Avni, R.; Spalvins, T.

1984-01-01

A detailed treatment is presented of the dialog known as plasma surface interactions (PSI) with respect to the coating process and its tribological behavior. Adsorption, morphological changes, defect formation, sputtering, chemical etching, and secondary electron emission are all discussed as promoting and enhancing the surface chemistry, thus influencing the tribological properties of the deposited flux. Phenomenological correlations of rate of deposition, flux composition, microhardness, and wear with the plasma layer variables give an insight to the formation of chemical bonding between the deposited flux and the substrate surface.

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.

On the evolution of morphology of zirconium sponge during reduction and distillation

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

Kapoor, K.; Padmaprabu, C.; Nandi, D.

2008-03-15

High purity zirconium metal is produced by magnesio-thermic reduction of zirconium tetrachloride followed by vacuum distillation. The reduction process is carried out in a batch giving metal sponge and magnesium chloride in the reduced mass. The sponge is purified to using by vacuum distillation. The morphology of the sponge formed during the reduction and its influence on further processing has significant importance. In the present study, a detailed investigation involving evolution of the morphology of sponge particles and its implication during the vacuum distillation was carried out. The study of the microstructure was done using scanning electron microscopy and X-raymore » diffraction. It is observed that the nascent sponge formed is highly unstable which transforms to a needle-like morphology almost immediately, which further transforms to rounded and finally to a bulk shape. Faceting of the surface and needle-shape formation were observed in these particles, this is probably due to anisotropy in the surface energy. The morphology of the sponge formed during the reduction influences the distillation process. The fine needle-like shape sponge morphology leads to particle ejection, which is explained to be due to curvature effect. This is responsible for the formation of unwanted mass during distillation. XRD line broadening analysis indicates that the individual sponge particles are free from structural defects (dislocation) and are nearly single crystalline in nature.« less

A new species of Trichuris from Thrichomys apereoides (Rodentia: Echimyidae) in Brazil: Morphological and histological studies.

PubMed

Torres, Eduardo J Lopes; Nascimento, Ariel P F; Menezes, Aleksandra O; Garcia, Juberlan; dos Santos, Marcos Antônio José; Maldonado, Arnaldo; Miranda, Kildare; Lanfredi, Reinalda M; de Souza, Wanderley

2011-03-10

Trichuris thrichomysi n. sp., recovered from the cecum of the wild rodent Thrichomys apereoides from a transition zone between the Atlantic Forest and Cerrado morfoclimatic domains, and its life cycle observed under experimental conditions are described. This new species is closely related to Trichuris travassosi, Trichuris chiliensis and Trichuris fulvi, but can be distinguished from them mainly by differences in the posterior end of males. Details of the surface such as the bacillary gland, cuticular inflations and several morphological details obtained by scanning electron microscopy and field emission scanning electron microscopy confirmed the characteristics that differentiate the new species. The histopathology of the intestinal wall of naturally infected rodents is also reported. The present study extends the geographical distribution of T. thrichomysi n. sp to the Pantanal ecosystem and reports a new host, Thrichomys pachiurus. Copyright © 2010 Elsevier B.V. All rights reserved.

Terrain-analysis procedures for modeling radar backscatter

USGS Publications Warehouse

Schaber, Gerald G.; Pike, Richard J.; Berlin, Graydon Lennis

1978-01-01

The collection and analysis of detailed information on the surface of natural terrain are important aspects of radar-backscattering modeling. Radar is especially sensitive to surface-relief changes in the millimeter- to-decimeter scale four conventional K-band (~1-cm wavelength) to L-band (~25-cm wavelength) radar systems. Surface roughness statistics that characterize these changes in detail have been generated by a comprehensive set of seven programmed calculations for radar-backscatter modeling from sets of field measurements. The seven programs are 1) formatting of data in readable form for subsequent topographic analysis program; 2) relief analysis; 3) power spectral analysis; 4) power spectrum plots; 5) slope angle between slope reversals; 6) slope angle against slope interval plots; and 7) base length slope angle and curvature. This complete Fortran IV software package, 'Terrain Analysis', is here presented for the first time. It was originally developed a decade ago for investigations of lunar morphology and surface trafficability for the Apollo Lunar Roving Vehicle.

Inductively coupled BCl 3/Cl 2 /Ar plasma etching of Al-rich AlGaN

DOE PAGES

Douglas, Erica A.; Sanchez, Carlos A.; Kaplar, Robert J.; ...

2016-12-01

Varying atomic ratios in compound semiconductors is well known to have large effects on the etching properties of the material. The use of thin device barrier layers, down to 25 nm, adds to the fabrication complexity by requiring precise control over etch rates and surface morphology. The effects of bias power and gas ratio of BCl 3 to Cl 2 for inductively coupled plasma etching of high Al content AlGaN were contrasted with AlN in this study for etch rate, selectivity, and surface morphology. Etch rates were greatly affected by both bias power and gas chemistry. Here we detail themore » effects of small variations in Al composition for AlGaN and show substantial changes in etch rate with regards to bias power as compared to AlN.« less

Reconstructing recent volcanic histories from high-resolution AUV sidescan sonar imagery

NASA Astrophysics Data System (ADS)

Yeo, I. A.

2016-12-01

Detecting high-resolution differences in age between young basaltic lava flows on the seafloor is notoriously difficult. However, using sediment thickness as a proxy for age it is possible to derive information on spatial extents, surface morphologies and lava flow age simultaneously using high-resolution sidescan sonar imagery. Ground truthing of this new method on cruise POS502 (July 2016) using photogrammetry from ROV cameras has provided constraints on the method allowing the detailed morphological changes and sediment cover thicknesses to be calibrated to produce reliable, quantitative ages for individual flow units. Sediment thickness is shown to be the primary controlling factor in backscatter intensity in most cases, although sediment redistribution by different flow morphologies can also affect the recorded reflection amplitudes. Seafloor lava flows were found to be very morphologically complicated on small scales, which may explain their relative unimportance when amplitude values are averaged over several tens of meters.

Removal of heavy metal ions by biogenic hydroxyapatite: Morphology influence and mechanism study

NASA Astrophysics Data System (ADS)

Wang, Dandan; Guan, Xiaomei; Huang, Fangzhi; Li, Shikuo; Shen, Yuhua; Chen, Jun; Long, Haibo

2016-08-01

Based on the synthesis of hydroxyapatite (HA) with different morphologies, such as nanorod-like, flower-like and sphere-like assembled HA nanorods, a new strategy has been developed for the removal of heavy metal ions such as Pb2+, Cu2+, Mn2+, Zn2+. The dependence of removal efficiency on the morphology and the suspended concentration of trapping agent, the removal time and selectivity were evaluated and discussed. The experimental results proved that the removal capacity of flower-like assembled HA nanorods (NAFL-HA) was the best, and the maximum removal ratio for Pb2+ ion was 99.97%. The mechanism of Pb2+ removal was studied in detail, noting that some metal ions were completely incorporated into hydroxyapatitie to produce Pb-HA. It reveals that the metal ions capture by HA is mainly controlled by sample surface adsorption and co-precipitation, which are directly controlled by sample morphology.

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.

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

Miao, Yinbin; Mo, Kun; Yao, Tiankai

Here coordinated experimental efforts to quantitatively correlate crystallographic orientation and surface faceting features in UO2 are reported upon. A sintered polycrystalline UO2 sample was thermally etched to induce the formation of surface faceting features. Synchrotron Laue microdiffraction was used to obtain a precise crystallographic orientation map for the UO2 surface grains. Scanning electron microscopy (SEM) was utilized to collect the detailed information on the surface morphology of the sample. The surface faceting features were found to be highly dependent on the crystallographic orientation. In most cases, Triple-plane structures containing one {100} plane and two {111} planes were found to dominatemore » the surface of UO2. The orientation-faceting relationship established in this study revealed a practical and efficient method of determining crystallographic orientation based on the surface features captured by SEM images.« less

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.

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.

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.

The role played by different TiO2 features on the photocatalytic degradation of paracetamol

NASA Astrophysics Data System (ADS)

Rimoldi, Luca; Meroni, Daniela; Falletta, Ermelinda; Ferretti, Anna Maria; Gervasini, Antonella; Cappelletti, Giuseppe; Ardizzone, Silvia

2017-12-01

Photocatalytic reactions promoted by TiO2 can be affected by a large number of oxide features (e.g. surface area, morphology and phase composition). In this context, the role played by the surface characteristics (e.g. surface acidity, wettability, etc.) has been often disregarded. In this work, pristine and Ta-doped TiO2 nanomaterials with different phase composition (pure anatase and anatase/brookite mixture) were synthesized by sol-gel and characterized under the structural and morphological point of view. A careful characterization of the acid properties of the materials has been performed by liquid-solid acid-base titration by means of 2-phenylethylamine (PEA) adsorption to determine the acid site density and average acid strength. Photocatalytic tests were performed in the degradation of paracetamol (acetaminophen) under UV irradiation and results were discussed in the light of the detailed scenarios describing the different oxides. The surface acidity of the samples, was recognized as one of the key parameters controlling the photocatalytic activity. A possible molecule degradation route is proposed on the ground of GC-MS and ESI-MS analyses.

Sinuous Flow in Cutting of Metals

NASA Astrophysics Data System (ADS)

Yeung, Ho; Viswanathan, Koushik; Udupa, Anirudh; Mahato, Anirban; Chandrasekar, Srinivasan

2017-11-01

Using in situ high-speed imaging, we unveil details of a highly unsteady plastic flow mode in the cutting of annealed and highly strain-hardening metals. This mesoscopic flow mode, termed sinuous flow, is characterized by repeated material folding, large rotation, and energy dissipation. Sinuous flow effects a very large shape transformation, with local strains of ten or more, and results in a characteristic mushroomlike surface morphology that is quite distinct from the well-known morphologies of metal-cutting chips. Importantly, the attributes of this unsteady flow are also fundamentally different from other well-established unsteady plastic flows in large-strain deformation, like adiabatic shear bands. The nucleation and development of sinuous flow, its dependence on material properties, and its manifestation across material systems are demonstrated. Plastic buckling and grain-scale heterogeneity are found to play key roles in triggering this flow at surfaces. Implications for modeling and understanding flow stability in large-strain plastic deformation, surface quality, and preparation of near-strain-free surfaces by cutting are discussed. The results point to the inadequacy of the widely used shear-zone models, even for ductile metals.

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.

Analysis of current-driven oscillatory dynamics of single-layer homoepitaxial islands on crystalline conducting substrates

NASA Astrophysics Data System (ADS)

Dasgupta, Dwaipayan; Kumar, Ashish; Maroudas, Dimitrios

2018-03-01

We report results of a systematic study on the complex oscillatory current-driven dynamics of single-layer homoepitaxial islands on crystalline substrate surfaces and the dependence of this driven dynamical behavior on important physical parameters, including island size, substrate surface orientation, and direction of externally applied electric field. The analysis is based on a nonlinear model of driven island edge morphological evolution that accounts for curvature-driven edge diffusion, edge electromigration, and edge diffusional anisotropy. Using a linear theory of island edge morphological stability, we calculate a critical island size at which the island's equilibrium edge shape becomes unstable, which sets a lower bound for the onset of time-periodic oscillatory dynamical response. Using direct dynamical simulations, we study the edge morphological dynamics of current-driven single-layer islands at larger-than-critical size, and determine the actual island size at which the migrating islands undergo a transition from steady to time-periodic asymptotic states through a subcritical Hopf bifurcation. At the highest symmetry of diffusional anisotropy examined, on {111} surfaces of face-centered cubic crystalline substrates, we find that more complex stable oscillatory states can be reached through period-doubling bifurcation at island sizes larger than those at the Hopf points. We characterize in detail the island morphology and dynamical response at the stable time-periodic asymptotic states, determine the range of stability of these oscillatory states terminated by island breakup, and explain the morphological features of the stable oscillating islands on the basis of linear stability theory.

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.

Further consideration of the curvature of the Neandertal Femur.

PubMed

Chapman, Tara; Sholukha, Victor; Semal, Patrick; Louryan, Stéphane; Van Sint Jan, Serge

2018-01-01

Neandertal femora are particularly known for having a marked sagittal femoral curvature. This study examined femoral curvature in Neandertals in comparison to a modern human population from Belgium by the use of three-dimensional (3D) quadric surfaces modeled from the bone surface. 3D models provide detailed information and enabled femoral curvature to be analyzed in conjunction with other morphological parameters. 3D models were created from CT scans of 75 modern human femora and 7 Neandertal femora. Quadric surfaces (QS) were created from the triangulated surface vertices in all areas of interest (neck, head, diaphyseal shaft, condyles) extracted from previously placed anatomical landmarks. The diaphyseal shaft was divided into five QS shapes and curvature was measured by degrees of difference between QS shapes. Each bone was placed in a local coordinate system enabling each bone to be analyzed in the same way. The use of 3D quadric surface fitting allowed the distribution of curvature with similarly curved femora to be analyzed and the different patterns of curvature between the two groups to be determined. The Neandertals were shown to have a higher degree of femoral curvature and a more distal point of femoral curvature than the modern human population from Belgium. Morphological aspects of the Neandertal femur are different from this modern human population although mainly seem unrelated to femoral curvature. The relative lack of correlations with other femoral bony morphological factors suggests femoral curvature variations may be related to other aspects. © 2017 Wiley Periodicals, Inc.

A New Design Strategy for Observing Lithium Oxide Growth-Evolution Interactions Using Geometric Catalyst Positioning.

PubMed

Ryu, Won-Hee; Gittleson, Forrest S; Li, Jinyang; Tong, Xiao; Taylor, André D

2016-08-10

Understanding the catalyzed formation and evolution of lithium-oxide products in Li-O2 batteries is central to the development of next-generation energy storage technology. Catalytic sites, while effective in lowering reaction barriers, often become deactivated when placed on the surface of an oxygen electrode due to passivation by solid products. Here we investigate a mechanism for alleviating catalyst deactivation by dispersing Pd catalytic sites away from the oxygen electrode surface in a well-structured anodic aluminum oxide (AAO) porous membrane interlayer. We observe the cross-sectional product growth and evolution in Li-O2 cells by characterizing products that grow from the electrode surface. Morphological and structural details of the products in both catalyzed and uncatalyzed cells are investigated independently from the influence of the oxygen electrode. We find that the geometric decoration of catalysts far from the conductive electrode surface significantly improves the reaction reversibility by chemically facilitating the oxidation reaction through local coordination with PdO surfaces. The influence of the catalyst position on product composition is further verified by ex situ X-ray photoelectron spectroscopy and Raman spectroscopy in addition to morphological studies.

A new design strategy for observing lithium oxide growth-evolution interactions using geometric catalyst positioning

DOE PAGES

Ryu, Won -Hee; Gittleson, Forrest S.; Li, Jinyang; ...

2016-06-21

Understanding the catalyzed formation and evolution of lithium-oxide products in Li-O 2 batteries is central to the development of next-generation energy storage technology. Catalytic sites, while effective in lowering reaction barriers, often become deactivated when placed on the surface of an oxygen electrode due to passivation by solid products. Here we investigate a mechanism for alleviating catalyst deactivation by dispersing Pd catalytic sites away from the oxygen electrode surface in a well-structured anodic aluminum oxide (AAO) porous membrane interlayer. We observe the cross-sectional product growth and evolution in Li-O 2 cells by characterizing products that grow from the electrode surface.more » Morphological and structural details of the products in both catalyzed and uncatalyzed cells are investigated independently from the influence of the oxygen electrode. We find that the geometric decoration of catalysts far from the conductive electrode surface significantly improves the reaction reversibility by chemically facilitating the oxidation reaction through local coordination with PdO surfaces. Lastly, the influence of the catalyst position on product composition is further verified by ex situ Xray photoelectron spectroscopy and Raman spectroscopy in addition to morphological studies.« less

Visualization and Quantitative Analysis of Crack-Tip Plastic Zone in Pure Nickel

NASA Astrophysics Data System (ADS)

Kelton, Randall; Sola, Jalal Fathi; Meletis, Efstathios I.; Huang, Haiying

2018-05-01

Changes in surface morphology have long been thought to be associated with crack propagation in metallic materials. We have studied areal surface texture changes around crack tips in an attempt to understand the correlations between surface texture changes and crack growth behavior. Detailed profiling of the fatigue sample surface was carried out at short fatigue intervals. An image processing algorithm was developed to calculate the surface texture changes. Quantitative analysis of the crack-tip plastic zone, crack-arrested sites near triple points, and large surface texture changes associated with crack release from arrested locations was carried out. The results indicate that surface texture imaging enables visualization of the development of plastic deformation around a crack tip. Quantitative analysis of the surface texture changes reveals the effects of local microstructures on the crack growth behavior.

[Studies on the tolerance of the organism to X 5 CrNiMo 18.10 steel (Königsee). II. Light microscopic studies of the surrounding tissue of metal implants (X 5 CrNiMo 18.10 steel) in guinea pigs].

PubMed

Höhndorf, H; Drössler, K; Stiehl, P

1977-06-01

The tissue around X 5 CrNiMo 18.10-steel implantates with different surfaces was examined in 72 guinea-pigs. Aside from controls, these animals were preoperatively sensibilized against chromium and nickel. The results can be summarized since the histologic findings showed no different peculiarities. The authors describe an intussusception of the implantate in connective tissue which evidently depends on time and surface. Further the spreading of alien material in the surrounding of the implantate, and morphologic findings are reported. The morphologic evidences are described and discussed in detail, since they are interpreted as signs of cell-mediated immune reactions. The presence of lymphocytes, lymphoblasts, histiocytes (mostly carrying alien material), and granulocytes, as well as proliferations at the arterioles suggest an overlapping of immune reactions.

The Impact History of Vesta: New Views from the Dawn Mission

NASA Technical Reports Server (NTRS)

OBrien, D. P.; Marchi, S.; Schenk, P.; Mittlefehldt, D. W.; Jaumann, R.; Ammannito, E.; Buczkowski, D. L.; DeSanctis, M. C.; Filacchione, G.; Gaskell, R.;

Interrogation of bimetallic particle oxidation in three dimensions at the nanoscale

PubMed Central

Han, Lili; Meng, Qingping; Wang, Deli; Zhu, Yimei; Wang, Jie; Du, Xiwen; Stach, Eric A.; Xin, Huolin L.

2016-01-01

An understanding of bimetallic alloy oxidation is key to the design of hollow-structured binary oxides and the optimization of their catalytic performance. However, one roadblock encountered in studying these binary oxide systems is the difficulty in describing the heterogeneities that occur in both structure and chemistry as a function of reaction coordinate. This is due to the complexity of the three-dimensional mosaic patterns that occur in these heterogeneous binary systems. By combining real-time imaging and chemical-sensitive electron tomography, we show that it is possible to characterize these systems with simultaneous nanoscale and chemical detail. We find that there is oxidation-induced chemical segregation occurring on both external and internal surfaces. Additionally, there is another layer of complexity that occurs during the oxidation, namely that the morphology of the initial oxide surface can change the oxidation modality. This work characterizes the pathways that can control the morphology in binary oxide materials. PMID:27928998

Snake fangs: 3D morphological and mechanical analysis by microCT, simulation, and physical compression testing.

PubMed

du Plessis, Anton; Broeckhoven, Chris; le Roux, Stephan G

2018-01-01

This Data Note provides data from an experimental campaign to analyse the detailed internal and external morphology and mechanical properties of venomous snake fangs. The aim of the experimental campaign was to investigate the evolutionary development of 3 fang phenotypes and investigate their mechanical behaviour. The study involved the use of load simulations to compare maximum Von Mises stress values when a load is applied to the tip of the fang. The conclusions of this study have been published elsewhere, but in this data note we extend the analysis, providing morphological comparisons including details such as curvature comparisons, thickness, etc. Physical compression results of individual fangs, though reported in the original paper, were also extended here by calculating the effective elastic modulus of the entire snake fang structure including internal cavities for the first time. This elastic modulus of the entire fang is significantly lower than the locally measured values previously reported from indentation experiments, highlighting the possibility that the elastic modulus is higher on the surface than in the rest of the material. The micro-computed tomography (microCT) data are presented both in image stacks and in the form of STL files, which simplifies the handling of the data and allows its re-use for future morphological studies. These fangs might also serve as bio-inspiration for future hypodermic needles. © The Author 2017. Published by Oxford University Press.

Inner Ear Morphology in the Atlantic Molly Poecilia mexicana—First Detailed Microanatomical Study of the Inner Ear of a Cyprinodontiform Species

PubMed Central

Schulz-Mirbach, Tanja; Heß, Martin; Plath, Martin

2011-01-01

Background Fishes show an amazing diversity in hearing abilities, inner ear structures, and otolith morphology. Inner ear morphology, however, has not yet been investigated in detail in any member of the diverse order Cyprinodontiformes. We, therefore, studied the inner ear of the cyprinodontiform freshwater fish Poecilia mexicana by analyzing the position of otoliths in situ, investigating the 3D structure of sensory epithelia, and examining the orientation patterns of ciliary bundles of the sensory hair cells, while combining μ-CT analyses, scanning electron microscopy, and immunocytochemical methods. P. mexicana occurs in different ecotypes, enabling us to study the intra-specific variability (on a qualitative basis) of fish from regular surface streams, and the Cueva del Azufre, a sulfidic cave in southern Mexico. Results The inner ear of Poecilia mexicana displays a combination of several remarkable features. The utricle is connected rostrally instead of dorso-rostrally to the saccule, and the macula sacculi, therefore, is very close to the utricle. Moreover, the macula sacculi possesses dorsal and ventral bulges. The two studied ecotypes of P. mexicana showed variation mainly in the shape and curvature of the macula lagenae, in the curvature of the macula sacculi, and in the thickness of the otolithic membrane. Conclusions Our study for the first time provides detailed insights into the auditory periphery of a cyprinodontiform inner ear and thus serves a basis—especially with regard to the application of 3D techniques—for further research on structure-function relationships of inner ears within the species-rich order Cyprinodontiformes. We suggest that other poeciliid taxa, or even other non-poeciliid cyprinodontiforms, may display similar inner ear morphologies as described here. PMID:22110746

Inner ear morphology in the Atlantic molly Poecilia mexicana--first detailed microanatomical study of the inner ear of a cyprinodontiform species.

PubMed

Schulz-Mirbach, Tanja; Hess, Martin; Plath, Martin

2011-01-01

Fishes show an amazing diversity in hearing abilities, inner ear structures, and otolith morphology. Inner ear morphology, however, has not yet been investigated in detail in any member of the diverse order Cyprinodontiformes. We, therefore, studied the inner ear of the cyprinodontiform freshwater fish Poecilia mexicana by analyzing the position of otoliths in situ, investigating the 3D structure of sensory epithelia, and examining the orientation patterns of ciliary bundles of the sensory hair cells, while combining μ-CT analyses, scanning electron microscopy, and immunocytochemical methods. P. mexicana occurs in different ecotypes, enabling us to study the intra-specific variability (on a qualitative basis) of fish from regular surface streams, and the Cueva del Azufre, a sulfidic cave in southern Mexico. The inner ear of Poecilia mexicana displays a combination of several remarkable features. The utricle is connected rostrally instead of dorso-rostrally to the saccule, and the macula sacculi, therefore, is very close to the utricle. Moreover, the macula sacculi possesses dorsal and ventral bulges. The two studied ecotypes of P. mexicana showed variation mainly in the shape and curvature of the macula lagenae, in the curvature of the macula sacculi, and in the thickness of the otolithic membrane. Our study for the first time provides detailed insights into the auditory periphery of a cyprinodontiform inner ear and thus serves a basis--especially with regard to the application of 3D techniques--for further research on structure-function relationships of inner ears within the species-rich order Cyprinodontiformes. We suggest that other poeciliid taxa, or even other non-poeciliid cyprinodontiforms, may display similar inner ear morphologies as described here.

Experimental investigation of the relationship between impact crater morphology and impacting particle velocity and direction

NASA Technical Reports Server (NTRS)

Mackay, N. G.; Green, S. F.; Gardner, D. J.; Mcdonnell, J. A. M.

1995-01-01

Interpretation of the wealth of impact data available from the Long Duration Exposure Facility, in terms of the absolute and relative populations of space debris and natural micrometeoroids, requires three dimensional models of the distribution of impact directions, velocities and masses of such particles, as well as understanding of the impact processes. Although the stabilized orbit of LDEF provides limited directional information, it is possible to determine more accurate impact directions from detailed crater morphology. The applicability of this technique has already been demonstrated but the relationship between crater shape and impactor direction and velocity has not been derived in detail. We present the results of impact experiments and simulations: (1) impacts at micron dimensions using the Unit's 2MV Van de Graaff accelerator; (2) impacts at mm dimensions using a Light Gas Gun; and (3) computer simulations using AUTODYN-3D from which an empirical relationship between crater shape and impactor velocity, direction and particle properties we aim to derive. Such a relationship can be applied to any surface exposed to space debris or micrometeoroid particles for which a detailed pointing history is available.

Correlation between Surface Tension and Water Activity in New Particle Formation

NASA Astrophysics Data System (ADS)

Daskalakis, E.; Salameh, A.

2016-12-01

The impact of aerosol properties on cloud dynamics and the radiative balance of the atmosphere relies on the parametrizations of cloud droplet formation. Such parametrization is based on equilibrium thermodynamics proposed by Köhler in 1936. There is considerable debate in the literature on the importance of factors like the surface tension depression or the water activity decrease for the correct parametrization. To gain fundamental insight into New Particle Formation (NPF), or Cloud Condensation Nuclei (CCN) activation one has to study microscopic properties of aqueous droplets, involving surface and bulk dynamics. The surface tension of droplets can be associated with the effects from Organic Matter (OM), whereas the static dielectric constant of water reflects the structure and dynamics of ions within solutions and can present a measure of water activity. In this study we employ Molecular Dynamics Simulations on aquatic droplets that contain surface active OM (acetaldehyde, methylglyoxal) and salts. We give insight into the dynamics of aquatic droplets with radials of 3.6nm at a level of detail that is not accessible experimentally (J. Phys. Chem. C 2016, 120:11508). We propose that as the surface tension of an aquatic droplet is decreased in the presence of surface-active OM, the water activity is affected as well. This is due to the fact that the water dipoles are oriented based on the salt morphology within the droplet. We suggest that the surface tension depression can be accompanied by the water activity change. This can be associated with the possible effects of surface-active species in terms of salt morphology transitions within an aerosol at the NPF and early particle growth time scales. Based on this study, surface-active OM seems important in controlling (a) the salt morphology transitions within a nucleus during NPF and particle growth and (b) a correlation between surface activity and water activity of ionic aquatic droplets. The latter correlation could be a fundamental property to consider when assessing NPF and the Köhler theory.

Allium ekimianum: a new species (Amaryllidaceae) from Turkey

PubMed Central

Ekşi, Gülnur; Koyuncu, Mehmet; Özkan, Ayşe Mine Gençler

2016-01-01

Abstract Allium ekimianum is described here as a new species. This taxon belongs to the genus Allium section Allium and grows in Elazığ Province (East Anatolia, Turkey). It is a narrowly distributed species and morphologically most similar to Allium asperiflorum and Allium sintenisii, and Allium erzincanicum but it is clearly differentiated due to the curved stem, smooth pedicel surfaces, bracteole arrangements at pedicel bases, tepal lengths and surfaces. In this study, a comprehensive description, distribution map of Allium ekimianum, identification key, and detailed illustrations are provided for Allium ekimianum and related taxa. PMID:27212884

Mercury's surface: Preliminary description and interpretation from Mariner 10 pictures

USGS Publications Warehouse

Murray, B.C.; Belton, M.J.S.; Danielson, G. Edward; Davies, M.E.; Gault, D.E.; Hapke, B.; O'Leary, B.; Strom, R.G.; Suomi, V.; Trask, N.

1974-01-01

The surface morphology and optical properties of Mercury resemble those of the moon in remarkable detail and record a very similar sequence of events. Chemical and mineralogical similarity of the outer layers of Mercury and the moon is implied; Mercury is probably a differentiated planet with a large iron-rich core. Differentiation is inferred to have occurred very early. No evidence of atmospheric modification of landforms has been found. Large-scale scarps and ridges unlike lunar or martian features may reflect a unique period of planetary compression near the end of heavy bombardment by small planetesimals.

[Hybrid 3-D rendering of the thorax and surface-based virtual bronchoscopy in surgical and interventional therapy control].

PubMed

Seemann, M D; Gebicke, K; Luboldt, W; Albes, J M; Vollmar, J; Schäfer, J F; Beinert, T; Englmeier, K H; Bitzer, M; Claussen, C D

2001-07-01

The aim of this study was to demonstrate the possibilities of a hybrid rendering method, the combination of a color-coded surface and volume rendering method, with the feasibility of performing surface-based virtual endoscopy with different representation models in the operative and interventional therapy control of the chest. In 6 consecutive patients with partial lung resection (n = 2) and lung transplantation (n = 4) a thin-section spiral computed tomography of the chest was performed. The tracheobronchial system and the introduced metallic stents were visualized using a color-coded surface rendering method. The remaining thoracic structures were visualized using a volume rendering method. For virtual bronchoscopy, the tracheobronchial system was visualized using a triangle surface model, a shaded-surface model and a transparent shaded-surface model. The hybrid 3D visualization uses the advantages of both the color-coded surface and volume rendering methods and facilitates a clear representation of the tracheobronchial system and the complex topographical relationship of morphological and pathological changes without loss of diagnostic information. Performing virtual bronchoscopy with the transparent shaded-surface model facilitates a reasonable to optimal, simultaneous visualization and assessment of the surface structure of the tracheobronchial system and the surrounding mediastinal structures and lesions. Hybrid rendering relieve the morphological assessment of anatomical and pathological changes without the need for time-consuming detailed analysis and presentation of source images. Performing virtual bronchoscopy with a transparent shaded-surface model offers a promising alternative to flexible fiberoptic bronchoscopy.

Polymethyl methacrylate-co-methacrylic acid coatings with controllable concentration of surface carboxyl groups: A novel approach in fabrication of polymeric platforms for potential bio-diagnostic devices

NASA Astrophysics Data System (ADS)

Hosseini, Samira; Ibrahim, Fatimah; Djordjevic, Ivan; Koole, Leo H.

2014-05-01

The generally accepted strategy in development of bio-diagnostic devices is to immobilize proteins on polymeric surfaces as a part of detection process for diseases and viruses through antibody/antigen coupling. In that perspective, polymer surface properties such as concentration of functional groups must be closely controlled in order to preserve the protein activity. In order to improve the surface characteristics of transparent polymethacrylate plastics that are used for diagnostic devices, we have developed an effective fabrication procedure of polymethylmetacrylate-co-metacrylic acid (PMMA-co-MAA) coatings with controlled number of surface carboxyl groups. The polymers were processed effectively with the spin-coating technique and the detailed control over surface properties is here by demonstrated through the variation of a single synthesis reaction parameter. The chemical structure of synthesized and processed co-polymers has been investigated with nuclear magnetic resonance spectroscopy (NMR) and matrix-assisted laser desorption time-of-flight mass spectrometry (MALDI-ToF-MS). The surface morphology of polymer coatings have been analyzed with atomic force microscopy (AFM) and scanning electron microscopy (SEM). We demonstrate that the surface morphology and the concentration of surface -COOH groups (determined with UV-vis surface titration) on the processed PMMA-co-MAA coatings can be precisely controlled by variation of initial molar ratio of reactants in the free-radical polymerization reaction. The wettability of developed polymer surfaces also varies with macromolecular structure.

Calculation of surface potentials at the silica–water interface using molecular dynamics: Challenges and opportunities

NASA Astrophysics Data System (ADS)

Lowe, Benjamin M.; Skylaris, Chris-Kriton; Green, Nicolas G.; Shibuta, Yasushi; Sakata, Toshiya

2018-04-01

Continuum-based methods are important in calculating electrostatic properties of interfacial systems such as the electric field and surface potential but are incapable of providing sufficient insight into a range of fundamentally and technologically important phenomena which occur at atomistic length-scales. In this work a molecular dynamics methodology is presented for interfacial electric field and potential calculations. The silica–water interface was chosen as an example system, which is highly relevant for understanding the response of field-effect transistors sensors (FET sensors). Detailed validation work is presented, followed by the simulated surface charge/surface potential relationship. This showed good agreement with experiment at low surface charge density but at high surface charge density the results highlighted challenges presented by an atomistic definition of the surface potential. This methodology will be used to investigate the effect of surface morphology and biomolecule addition; both factors which are challenging using conventional continuum models.

A nanoforest structure for practical surface-enhanced Raman scattering substrates

NASA Astrophysics Data System (ADS)

Seol, Myeong-Lok; Choi, Sung-Jin; Baek, David J.; Park, Tae Jung; Ahn, Jae-Hyuk; Lee, Sang Yup; Choi, Yang-Kyu

2012-03-01

A nanoforest structure for surface-enhanced Raman scattering (SERS) active substrates is fabricated and analyzed. The detailed morphology of the resulting structure can be easily controlled by modifying the process parameters such as initial gold layer thickness and etching time. The applicability of the nanoforest substrate as a label-free SERS immunosensor is demonstrated using influenza A virus subtype H1N1. Selective binding of the H1N1 surface antigen and the anti-H1 antibody is directly detected by the SERS signal differences. Simple fabrication and high throughput with strong in-plane hot-spots imply that the nanoforest structure can be a practical sensing component of a chip-based SERS sensing system.

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.

Leaf micro-morphology of Lepisanthes Blume (Sapindaceae) in Peninsular Malaysia

NASA Astrophysics Data System (ADS)

Ghazalli, Mohd Norfaizal; Talib, Noraini; Mohammad, Abdul Latiff

2018-04-01

A detail comparative study on leaf micro-morphology was conducted on the genus Lepisanthes from Peninsular Malaysia, five chosen species namely as L. amoena (Hassk.) Leenh., L. fruticosa (Roxb.) Leenh., L. rubiginosa (Roxb.) Leenh., L. senegalensis (Juss. ex Poir.) Leenh. and L. tetraphylla (Vahl.) Radlk. The objective of this study is to identify the leaf micro-morphological characteristics that can give significance impact for species identification and classification. Lepisanthes is an important tropical rare fruit genus in Malaysia and it is important to characterize and documenting additional taxonomic evidences that can be useful in Sapindaceae taxonomy information which is still lacked. The methods involved dehydration process, critical point drying, gold coated and observation under scanning electron microscope. Leaf micro-morphology showed significance taxonomic value in the genus Lepisanthes and can be used as additional data for species identification. Diagnostic character was found in L. fruticosa via the presence of four different types of trichomes on the abaxial and adaxial epidermal surfaces. As a conclusion, variation in cuticular striation, stomata structure, type of waxes and trichome morphology can be used in Lepisanthes species identification.

Concurrent segregation and erosion effects in medium-energy iron beam patterning of silicon surfaces

NASA Astrophysics Data System (ADS)

Redondo-Cubero, A.; Lorenz, K.; Palomares, F. J.; Muñoz, A.; Castro, M.; Muñoz-García, J.; Cuerno, R.; Vázquez, L.

2018-07-01

We have bombarded crystalline silicon targets with a 40 keV Fe+ ion beam at different incidence angles. The resulting surfaces have been characterized by atomic force, current-sensing and magnetic force microscopies, scanning electron microscopy, and x-ray photoelectron spectroscopy. We have found that there is a threshold angle smaller than 40° for the formation of ripple patterns, which is definitely lower than those frequently reported for noble gas ion beams. We compare our observations with estimates of the value of the critical angle and of additional basic properties of the patterning process, which are based on a continuum model whose parameters are obtained from binary collision simulations. We have further studied experimentally the ripple structures and measured how the surface slopes change with the ion incidence angle. We explore in particular detail the fluence dependence of the pattern for an incidence angle value (40°) close to the threshold. Initially, rimmed holes appear randomly scattered on the surface, which evolve into large, bug-like structures. Further increasing the ion fluence induces a smooth, rippled background morphology. By means of microscopy techniques, a correlation between the morphology of these structures and their metal content can be unambiguously established.

Effect of wood flour content on the optical color, surface chemistry, mechanical and morphological properties of wood flour/recycled high density polyethylene (rHDPE) composite

NASA Astrophysics Data System (ADS)

Sheng, Chan Kok; Amin, Khairul Anuar Mat; Kee, Kwa Bee; Hassan, Mohd Faiz; Ali, E. Ghapur E.

2018-05-01

In this study, effect of wood flour content on the color, surface chemistry, mechanical properties and surface morphology of wood-plastic composite (WPC) on different mixture ratios of recycled high density polyethylene (rHDPE) and wood flour were investigated in detail. The presence of wood flour in the composite indicates a significant total color change and a decrease of lightness. Functional groups of wood flour in WPC can be seen clearer from the Fourier transform infrared (FTIR) spectra as the wood flour content increases. The mechanical tensile testing shows that the tensile strength of Young's modulus is improved, whereas the strain and elongation at break were reduced by the addition of wood flour. The gap between the wood flour microvoid fibre and rHDPE matrix becomes closer when the wood flour content is increased as observed by scanning electron microscope (SEM) image. This finding implies a significant improvement on the interaction of interfacial adhesion between the rHDPE matrix and wood flour filler in the present WPC.

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.

An optimized methodology to analyze biopolymer capsules by environmental scanning electron microscopy.

PubMed

Conforto, Egle; Joguet, Nicolas; Buisson, Pierre; Vendeville, Jean-Eudes; Chaigneau, Carine; Maugard, Thierry

2015-02-01

The aim of this paper is to describe an optimized methodology to study the surface characteristics and internal structure of biopolymer capsules using scanning electron microscopy (SEM) in environmental mode. The main advantage of this methodology is that no preparation is required and, significantly, no metallic coverage is deposited on the surface of the specimen, thus preserving the original capsule shape and its surface morphology. This avoids introducing preparation artefacts which could modify the capsule surface and mask information concerning important feature like porosities or roughness. Using this method gelatin and mainly fatty coatings, difficult to be analyzed by standard SEM technique, unambiguously show fine details of their surface morphology without damage. Furthermore, chemical contrast is preserved in backscattered electron images of unprepared samples, allowing visualizing the internal organization of the capsule, the quality of the envelope, etc... This study provides pointers on how to obtain optimal conditions for the analysis of biological or sensitive material, as this is not always studied using appropriate techniques. A reliable evaluation of the parameters used in capsule elaboration for research and industrial applications, as well as that of capsule functionality is provided by this methodology, which is essential for the technological progress in this domain. Copyright © 2014 Elsevier B.V. All rights reserved.

Effects of experimental conditions on the morphologies, structures and growth modes of pulsed laser-deposited CdS nanoneedles

PubMed Central

2014-01-01

CdS nanoneedles with different morphologies, structures, and growth modes have been grown on Ni-coated Si(100) surface under different experimental conditions by pulsed laser deposition method. The effects of catalyst layer, substrate temperature, and laser pulse energy on the growth of the CdS nanoneedles were studied in detail. It was confirmed that the formation of the molten catalyst spheres is the key to the nucleation of the CdS nanoneedles by observing the morphologies of the Ni catalyst thin films annealed at different substrate temperatures. Both the substrate temperature and laser pulse energy strongly affected the growth modes of the CdS nanoneedles. The secondary growth of the smaller nanoneedles on the top of the main nanoneedles was found at appropriate conditions. A group of more completed pictures of the growth modes of the CdS nanoneedles were presented. PMID:24559455

Polyethyleneimine functionalized platinum superstructures: enhancing hydrogen evolution performance by morphological and interfacial control† †Electronic supplementary information (ESI) available: Experimental details and additional physical characterization. See DOI: 10.1039/c7sc04109h

PubMed Central

Xu, Guang-Rui; Bai, Juan; Jiang, Jia-Xing

2017-01-01

The electrocatalytic hydrogen evolution reaction (HER) is a highly promising green method for sustainable and efficient hydrogen production. So far, Pt nanocrystals are still the most active electrocatalysts for the HER in acidic media, although a tremendous search for alternatives has been done in the past decade. In this work, we synthesize polyethyleneimine (PEI) functionalized Pt superstructures (Pt-SSs@PEI) with tetragonal, hierarchical, and branched morphologies with a facile wet chemical reduction method. A series of physical characterizations are conducted to investigate the morphology, electronic structure, surface composition, and formation mechanism of Pt-SSs@PEI. Impressively, the as-prepared Pt-SSs@PEI show an unprecedented onset reduction potential (+64.6 mV vs. reversible hydrogen electrode) for the HER in strong acidic media due to the protonation of –NH2 groups in the PEI adlayers on the Pt surface, and they outperform all currently reported HER electrocatalysts. The work highlights a highly effective interface-engineering strategy for improving the electrocatalytic performance of Pt nanocrystals for the HER. PMID:29619188

Deep UV Native Fluorescence Imaging of Antarctic Cryptoendolithic Communities

NASA Technical Reports Server (NTRS)

Storrie-Lombardi, M. C.; Douglas, S.; Sun, H.; McDonald, G. D.; Bhartia, R.; Nealson, K. H.; Hug, W. F.

2001-01-01

An interdisciplinary team at the Jet Propulsion Laboratory Center for Life Detection has embarked on a project to provide in situ chemical and morphological characterization of Antarctic cryptoendolithic microbial communities. We present here in situ deep ultraviolet (UV) native fluorescence and environmental scanning electron microscopy images transiting 8.5 mm into a sandstone sample from the Antarctic Dry Valleys. The deep ultraviolet imaging system employs 224.3, 248.6, and 325 nm lasers to elicit differential fluorescence and resonance Raman responses from biomolecules and minerals. The 224.3 and 248.6 nm lasers elicit a fluorescence response from the aromatic amino and nucleic acids. Excitation at 325 nm may elicit activity from a variety of biomolecules, but is more likely to elicit mineral fluorescence. The resultant fluorescence images provide in situ chemical and morphological maps of microorganisms and the associated organic matrix. Visible broadband reflectance images provide orientation against the mineral background. Environmental scanning electron micrographs provided detailed morphological information. The technique has made possible the construction of detailed fluorescent maps extending from the surface of an Antarctic sandstone sample to a depth of 8.5 mm. The images detect no evidence of microbial life in the superficial 0.2 mm crustal layer. The black lichen component between 0.3 and 0.5 mm deep absorbs all wavelengths of both laser and broadband illumination. Filamentous deep ultraviolet native fluorescent activity dominates in the white layer between 0.6 mm and 5.0 mm from the surface. These filamentous forms are fungi that continue into the red (iron-rich) region of the sample extending from 5.0 to 8.5 mm. Using differential image subtraction techniques it is possible to identify fungal nuclei. The ultraviolet response is markedly attenuated in this region, apparently from the absorption of ultraviolet light by iron-rich particles coating the filaments. Below 8.5 mm the filamentous morphology of the upper layers gives way to punctate 1-2 micron particles evidencing fluorescent activity following excitation at both deep ultraviolet wavelengths.

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

Peristome as a potential tool for delimiting Bryum Hedw. (Bryaceae) from India.

PubMed

Bansal, Pooja; Nath, Virendra

2018-02-26

The peristome, an interesting and important taxonomic structure used in the systematics of mosses, is for the first time studied in detail for 21 taxa of Bryum, which constitute a fraction of Indian representatives. Macro- and micro-morphological characters including color, size and length of two components of peristome, tapering pattern, median line, and papillosity at upper part under light microscope; width of exostome border, number and inner surface of ventral trabeculae, presence or absence of longitudinal/oblique septae between ventral trabeculae, pattern of exostome surface and height of endostomial basal membrane, adherence, perforations, and surface of cilia under scanning electron microscope were examined to bring out submicroscopic differences. Detail surface structure of eight taxa, viz., B. apalodictyoides, B. evanidinerve, B. pachytheca, B. pseudotriquetrum var. subrotundum, B. reflexifolium, B. thomsonii, B. tuberosum, and B. turbinatum, under LM and nine species, namely, B. apalodictyoides, B. apiculatum, B. argenteum, B. billarderi, B. dichotomum, B. evanidinerve, B. recurvulum, B. turbinatum, and B. uliginosum, under SEM is being provided for the first time. Description of peristome surface and a key based on SEM and other taxonomical features is also being provided. The data obtained from the present study suggest that the species of this genus can easily be distinguished on the basis of peristomial surface pattern.

Morphological evidences in circumvallate papilla and von Ebners' gland development in mice

PubMed Central

Sohn, Wern-Joo; Gwon, Gi-Jeong; An, Chang-Hyeon; Moon, Cheil; Bae, Yong-Chul; Yamamoto, Hitoshi; Lee, Sanggyu

2011-01-01

In rodents, the circumvallate papilla (CVP), with its underlying minor salivary gland, the von Ebners' gland (VEG), is located on the dorsal surface of the posterior tongue. Detailed morphological processes to form the proper structure of CVP and VEG have not been properly elucidated. In particular, the specific localization patterns of taste buds in CVP and the branching formation of VEG have not yet been elucidated. To understand the developmental mechanisms underlying CVP and VEG formation, detailed histological observations of CVP and VEG were examined using a three-dimensional computer-aided reconstruction method with serial histological sections and pan-Cytokeratins immunostainings. In addition, to define the developmental processes in CVP and VEG formation, we examined nerve innervations and cell proliferation using microinjections of AM1-43 and immunostainings with various markers, including phosphoinositide 3-kinase, Ki-67, PGP9.5, and Ulex europaeus agglutinin 1 (UEA1). Results revealed specific morphogenesis of CVP and VEG with nerve innervations patterns, evaluated by the coincided localization patterns of AM1-43 and UEA1. Based on these morphological and immunohistochemical results, we suggest that nerve innervations and cell proliferations play important roles in the positioning of taste buds in CVP and branching morphogenesis of VEG in tongue development. PMID:22254156

Spallation-induced roughness promoting high spatial frequency nanostructure formation on Cr

NASA Astrophysics Data System (ADS)

Abou-Saleh, A.; Karim, E. T.; Maurice, C.; Reynaud, S.; Pigeon, F.; Garrelie, F.; Zhigilei, L. V.; Colombier, J. P.

2018-04-01

Interaction of ultrafast laser pulses with metal surfaces in the spallation regime can result in the formation of anisotropic nanoscale surface morphology commonly referred to as laser-induced periodic surface structures (LIPSS) or ripples. The surface structures generated by a single pulse irradiation of monocrystalline Cr samples are investigated experimentally and computationally for laser fluences that produce high spatial frequency nanostructures in the multi-pulse irradiation regime. Electron microscopy reveals distinct response of samples with different crystallographic surface orientations, with (100) surfaces exhibiting the formation of more refined nanostructure by a single pulse irradiation and a more pronounced LIPSS after two laser pulses as compared to (110) surfaces. A large-scale molecular dynamics simulation of laser interaction with a (100) Cr target provides detailed information on processes responsible for spallation of a liquid layer, redistribution of molten material, and rapid resolidification of the target. The nanoscale roughness of the resolidified surface predicted in the simulation features elongated frozen nanospikes, nanorims and nanocavities with dimensions and surface density similar to those in the surface morphology observed for (100) Cr target with atomic force microscopy. The results of the simulation suggest that the types, sizes and dimensions of the nanoscale surface features are defined by the competition between the evolution of transient liquid structures generated in the spallation process and the rapid resolidification of the surface region of the target. The spallation-induced roughness is likely to play a key role in triggering the generation of high-frequency LIPSS upon irradiation by multiple laser pulses.

Tuning Surface Chemistry of Polyetheretherketone by Gold Coating and Plasma Treatment

NASA Astrophysics Data System (ADS)

Novotná, Zdeňka; Rimpelová, Silvie; Juřík, Petr; Veselý, Martin; Kolská, Zdeňka; Hubáček, Tomáš; Borovec, Jakub; Švorčík, Václav

2017-06-01

Polyetheretherketone (PEEK) has good chemical and biomechanical properties that are excellent for biomedical applications. However, PEEK exhibits hydrophobic and other surface characteristics which cause limited cell adhesion. We have investigated the potential of Ar plasma treatment for the formation of a nanostructured PEEK surface in order to enhance cell adhesion. The specific aim of this study was to reveal the effect of the interface of plasma-treated and gold-coated PEEK matrices on adhesion and spreading of mouse embryonic fibroblasts. The surface characteristics (polarity, surface chemistry, and structure) before and after treatment were evaluated by various experimental techniques (gravimetry, goniometry, X-ray photoelectron spectroscopy (XPS), and electrokinetic analysis). Further, atomic force microscopy (AFM) was employed to examine PEEK surface morphology and roughness. The biological response of cells towards nanostructured PEEK was evaluated in terms of cell adhesion, spreading, and proliferation. Detailed cell morphology was evaluated by scanning electron microscopy (SEM). Compared to plasma treatment, gold coating improved PEEK wettability. The XPS method showed a decrease in the carbon concentration with increasing time of plasma treatment. Cell adhesion determined on the interface between plasma-treated and gold-coated PEEK matrices was directly proportional to the thickness of a gold layer on a sample. Our results suggest that plasma treatment in a combination with gold coating could be used in biomedical applications requiring enhanced cell adhesion.

Graphite carbon nitride/boron-doped graphene hybrid for efficient hydrogen generation reaction.

PubMed

Yang, Liang; Wang, Xin; Wang, Juan; Cui, Guomin; Liu, Daoping

2018-08-24

Metal-free carbon materials, with tuned surface chemical and electronic properties, hold great potential for the hydrogen evolution reaction (HER). We designed and synthesized a CN/BG hybrid electrocatalytic system with a porous and active graphite carbon nitride (CN) layer on boron-doped graphene (BG). A porous CN layer on graphene could provide exposed defects and edges that act as active sites for proton adsorption and reduction. The composition, structure, surface electronics, and chemical properties of this CN/BG hybrid system were tuned to obtain excellent HER activity and stability. Detailed surface chemical, morphological, and structural analyses demonstrated the synergetic effect arising from the electronic interaction between CN and BG, which contributed to the enhanced electrocatalytic performances.

Surface smoothening effects on growth of diamond films

NASA Astrophysics Data System (ADS)

Reshi, Bilal Ahmad; Kumar, Shyam; Kartha, Moses J.; Varma, Raghava

2018-04-01

We have carried out a detailed study of the growth dynamics of the diamond film during initial time on diamond substrates. The diamond films are deposited using Microwave Plasma Chemical Vapor Deposition (MPCVD) method for different times. Surface morphology and its correlation with the number of hours of growth of thin films was invested using atomic force microscopy (AFM). Diamond films have smooth interface with average roughness of 48.6873nm. The initial growth dynamics of the thin film is investigated. Interestingly, it is found that there is a decrease in the surface roughness of the film. Thus a smoothening effect is observed in the grown films. The film enters into the growth regime in the later times. Our results also find application in building diamond detector.

Hydrothermal-electrochemical growth of heterogeneous ZnO: Co films

NASA Astrophysics Data System (ADS)

Yilmaz, Ceren; Unal, Ugur

2017-10-01

This study demonstrates the preparation of heterogeneous ZnO: Co nanostructures via hydrothermal-electrochemical deposition at 130 °C and -1.1 V (vs Ag/AgCl (satd)) in dimethyl sulfoxide (DMSO)-H2O mixture. Under the stated conditions, ZnO: Co nanostructures grow preferentially along (002) direction. Strength of directional growth progressively increases with the increasing concentration of Co(II) in the deposition bath. Films are composed of hexagonal Wurtzite ZnO, metallic cobalt, and mixed cobalt oxide on the surface and cobalt(II) oxide in deeper levels. Increasing the Co(II) concentration in the deposition bath results in different morphological features as well as phase separation. Platelets, sponge-like structures, cobalt-rich spheres, microislands of cobalt-rich spheres which are interconnected by ZnO network can be synthesized by adjusting [Co(II)]: [Zn(II)] ratio. Growth mechanisms giving rise to these particular structures, surface morphology, crystal structure, phase purity, chemical binding characteristics, and optical properties of the deposits are discussed in detail.

Boundary condition of grounding lines prior to collapse, Larsen-B Ice Shelf, Antarctica.

PubMed

Rebesco, M; Domack, E; Zgur, F; Lavoie, C; Leventer, A; Brachfeld, S; Willmott, V; Halverson, G; Truffer, M; Scambos, T; Smith, J; Pettit, E

2014-09-12

Grounding zones, where ice sheets transition between resting on bedrock to full floatation, help regulate ice flow. Exposure of the sea floor by the 2002 Larsen-B Ice Shelf collapse allowed detailed morphologic mapping and sampling of the embayment sea floor. Marine geophysical data collected in 2006 reveal a large, arcuate, complex grounding zone sediment system at the front of Crane Fjord. Radiocarbon-constrained chronologies from marine sediment cores indicate loss of ice contact with the bed at this site about 12,000 years ago. Previous studies and morphologic mapping of the fjord suggest that the Crane Glacier grounding zone was well within the fjord before 2002 and did not retreat further until after the ice shelf collapse. This implies that the 2002 Larsen-B Ice Shelf collapse likely was a response to surface warming rather than to grounding zone instability, strengthening the idea that surface processes controlled the disintegration of the Larsen Ice Shelf. Copyright © 2014, American Association for the Advancement of Science.

Interrogation of bimetallic particle oxidation in three dimensions at the nanoscale

DOE PAGES

Han, Lili; Meng, Qingping; Wang, Deli; ...

2016-12-08

An understanding of bimetallic alloy oxidation is key to the design of hollow-structured binary oxides and the optimization of their catalytic performance. However, one roadblock encountered in studying these binary oxide systems is the difficulty in describing the heterogeneities that occur in both structure and chemistry as a function of reaction coordinate. This is due to the complexity of the three-dimensional mosaic patterns that occur in these heterogeneous binary systems. By combining real-time imaging and chemical-sensitive electron tomography, we show that it is possible to characterize these systems with simultaneous nanoscale and chemical detail. We find that there is oxidation-inducedmore » chemical segregation occurring on both external and internal surfaces. Additionally, there is another layer of complexity that occurs during the oxidation, namely that the morphology of the initial oxide surface can change the oxidation modality. As a result, this work characterizes the pathways that can control the morphology in binary oxide materials.« less

Integrated approach to characterize fouling on a flat sheet membrane gravity driven submerged membrane bioreactor.

PubMed

Fortunato, Luca; Jeong, Sanghyun; Wang, Yiran; Behzad, Ali R; Leiknes, TorOve

2016-12-01

Fouling in membrane bioreactors (MBR) is acknowledged to be complex and unclear. An integrated characterization methodology was employed in this study to understand the fouling on a gravity-driven submerged MBR (GD-SMBR). It involved the use of different analytical tools, including optical coherence tomography (OCT), liquid chromatography with organic carbon detection (LC-OCD), total organic carbon (TOC), flow cytometer (FCM), adenosine triphosphate analysis (ATP) and scanning electron microscopy (SEM). The three-dimensional (3D) biomass morphology was acquired in a real-time through non-destructive and in situ OCT scanning of 75% of the total membrane surface directly in the tank. Results showed that the biomass layer was homogeneously distributed on the membrane surface. The amount of biomass was selectively linked with final destructive autopsy techniques. The LC-OCD analysis indicated the abundance of low molecular weight (LMW) organics in the fouling composition. Three different SEM techniques were applied to investigate the detailed fouling morphology on the membrane. Copyright © 2016 Elsevier Ltd. All rights reserved.

Viscoelasticity of thin biomolecular films: a case study on nucleoporin phenylalanine-glycine repeats grafted to a histidine-tag capturing QCM-D sensor.

PubMed

Eisele, Nico B; Andersson, Fredrik I; Frey, Steffen; Richter, Ralf P

2012-08-13

Immobilization of proteins onto surfaces is useful for the controlled generation of biomolecular assemblies that can be readily characterized with in situ label-free surface-sensitive techniques. Here we analyze the performance of a quartz crystal microbalance with dissipation monitoring (QCM-D) sensor surface that enables the selective and oriented immobilization of histidine-tagged molecules for morphological and interaction studies. More specifically, we characterize monolayers of natively unfolded nucleoporin domains that are rich in phenylalanine-glycine repeats (FGRDs). An FGRD meshwork is thought to be responsible for the selectivity of macromolecular transport across the nuclear pore complex between the cytosol and the nucleus of living cells. We demonstrate that nucleoporin FGRD films can be formed on His-tag Capturing Sensors with properties comparable to a previously reported immobilization platform based on supported lipid bilayers (SLB). Approaches to extract the film thickness and viscoelastic properties in a time-resolved manner from the QCM-D response are described, with particular emphasis on the practical implementation of viscoelastic modeling and a detailed analysis of the quality and reliability of the fit. By comparing the results with theoretical predictions for the viscoelastic properties of polymer solutions and gels, and experimental data from an atomic force microscopy indentation assay, we demonstrate that detailed analysis can provide novel insight into the morphology and dynamics of FG repeat domain films. The immobilization approach is simple and versatile, and can be easily extended to other His-tagged biomolecules. The data analysis procedure should be useful for the characterization of other ultrathin biomolecular and polymer films.

Simple synthetic route for hydroxyapatite colloidal nanoparticles via a Nd:YAG laser ablation in liquid medium

NASA Astrophysics Data System (ADS)

Mhin, Sung Wook; Ryu, Jeong Ho; Kim, Kang Min; Park, Gyeong Seon; Ryu, Han Wool; Shim, Kwang Bo; Sasaki, Takeshi; Koshizaki, Naoto

2009-08-01

Pulsed laser ablation (PLA) in liquid medium was successfully employed to synthesize hydroxyapatite (HAp) colloidal nanoparticles. The crystalline phase, particle morphology, size distribution and microstructure of the HAp nanoparticles were investigated in detail. The obtained HAp nanoparticles had spherical shape with sizes ranging from 5 to 20 nm. The laser ablation and the nanoparticle forming process were studied in terms of the explosive ejection mechanism by investigating the change of the surface morphology on target. The stoichiometry and bonding properties were studied by using XPS, FT-IR and Raman spectroscopy. A molar ratio of Ca/P of the prepared HAp nanoparticles was more stoichiometric than the value reported in the case of ablation in vacuum.

Crustal and subcrustal nodules in ejecta from Kilbourne Hole Maar, New Mexico

NASA Technical Reports Server (NTRS)

Whitford-Stark, J. L.

1987-01-01

Nodules retrieved from the ejecta of volcanic craters serve as the source of two major items of information. The first is in providing details of the geochemistry and mineralogy of the Earth's interior by supplying samples of materials that cannot be obtained by existing drilling techniques. The other is in providing information regarding the process which led to their transport from the Earth's interior to the surface. The primary purpose of the present study was to examine the morphology of the nodules in an attempt to place some constraints on the process that brought them to the surface. This attempt is briefly discussed.

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

Moussa, Sana Ben; Bachouâ, Hassen; Gruselle, Michel, E-mail: michel.gruselle@upmc.fr

The present article details the formation of calcium hydroxyapatite synthesized by the hydrothermal way, in presence of glycine or sarcosine. The presence of these amino-acids during the synthetic processes reduces the crystalline growthing through the formation of hybrid organic-inorganic species The crystallite sizes are decreasing and the morphology is modified with the increase of the amino-acid concentration. - Graphical abstract: Formation of Ca carboxylate salt leading to the grafting of glycine and sarcosine on the Ca=Hap surface (R= H, CH3).

Mapping the Complex Morphology of Cell Interactions with Nanowire Substrates Using FIB-SEM

PubMed Central

Jensen, Mikkel R. B.; Łopacińska, Joanna; Schmidt, Michael S.; Skolimowski, Maciej; Abeille, Fabien; Qvortrup, Klaus; Mølhave, Kristian

2013-01-01

Using high resolution focused ion beam scanning electron microscopy (FIB-SEM) we study the details of cell-nanostructure interactions using serial block face imaging. 3T3 Fibroblast cellular monolayers are cultured on flat glass as a control surface and on two types of nanostructured scaffold substrates made from silicon black (Nanograss) with low- and high nanowire density. After culturing for 72 hours the cells were fixed, heavy metal stained, embedded in resin, and processed with FIB-SEM block face imaging without removing the substrate. The sample preparation procedure, image acquisition and image post-processing were specifically optimised for cellular monolayers cultured on nanostructured substrates. Cells display a wide range of interactions with the nanostructures depending on the surface morphology, but also greatly varying from one cell to another on the same substrate, illustrating a wide phenotypic variability. Depending on the substrate and cell, we observe that cells could for instance: break the nanowires and engulf them, flatten the nanowires or simply reside on top of them. Given the complexity of interactions, we have categorised our observations and created an overview map. The results demonstrate that detailed nanoscale resolution images are required to begin understanding the wide variety of individual cells’ interactions with a structured substrate. The map will provide a framework for light microscopy studies of such interactions indicating what modes of interactions must be considered. PMID:23326412

ALAMEDA, a Structural–Functional Model for Faba Bean Crops: Morphological Parameterization and Verification

PubMed Central

RUIZ-RAMOS, MARGARITA; MÍNGUEZ, M. INÉS

2006-01-01

• Background Plant structural (i.e. architectural) models explicitly describe plant morphology by providing detailed descriptions of the display of leaf and stem surfaces within heterogeneous canopies and thus provide the opportunity for modelling the functioning of plant organs in their microenvironments. The outcome is a class of structural–functional crop models that combines advantages of current structural and process approaches to crop modelling. ALAMEDA is such a model. • Methods The formalism of Lindenmayer systems (L-systems) was chosen for the development of a structural model of the faba bean canopy, providing both numerical and dynamic graphical outputs. It was parameterized according to the results obtained through detailed morphological and phenological descriptions that capture the detailed geometry and topology of the crop. The analysis distinguishes between relationships of general application for all sowing dates and stem ranks and others valid only for all stems of a single crop cycle. • Results and Conclusions The results reveal that in faba bean, structural parameterization valid for the entire plant may be drawn from a single stem. ALAMEDA was formed by linking the structural model to the growth model ‘Simulation d'Allongement des Feuilles’ (SAF) with the ability to simulate approx. 3500 crop organs and components of a group of nine plants. Model performance was verified for organ length, plant height and leaf area. The L-system formalism was able to capture the complex architecture of canopy leaf area of this indeterminate crop and, with the growth relationships, generate a 3D dynamic crop simulation. Future development and improvement of the model are discussed. PMID:16390842

The Evolution of a Snow Dune Field

NASA Astrophysics Data System (ADS)

Filhol, S.; Pirk, N.; Schuler, T.; Burkhart, J. F.

2017-12-01

On March 24, 2017 we observed the evolution of a snow dune field during a passing storm on the alpine plateau of Finse, Norway. With a terrestrial lidar we captured 15 high-resolution scans of the snow surface over an area of about 5000 m2 over the course of 7.5 hours from which we analyze morphological changes. An eddy covariance system located nearby at the Finse Alpine Research Station recorded wind and its turbulent structure, and measured the snow drifting flux with a FlowCapt sensor. This combined dataset provides novel insight into the responses and changes of the snow surface morphology exposed to storm constraints (e.g. wind speed, drifting flux). We found that individual dunes have moved 30 to 37 m over the course of 7.5 hours. The wavelength of the dunes varied from 10.3±3.1 m at the time of the first scan to 13.6±3.3 m at the last scan. Within this time period we observed individual dunes 1) migrating down wind, later becoming 2) temporarily nearly static as the wind speed dropped, and finally 3) migrating, growing, and merging into larger transverse dunes under strong wind conditions accompanied by large quantities of drifting snow. This dynamics can be considered analogous to sand dune behavior, however, on much shorter time scale (1h vs 10-100 years) and smaller spatial scale (10m vs 100m). The record of this event helps us to understand the morphological evolution of a snow surface during a blowing snow storm, and further illustrates the fate of self-sustained bedforms such as dunes in varying conditions. Such detailed description of erosion/deposition processes of the snow surface are crucial for improvements of land surface models, commonly applied to hydrological and ecological purposes.

Mars Field Geology, Biology. and Paleontology Workshop: Summary and Recommendations

NASA Technical Reports Server (NTRS)

Budden, Nancy Ann (Editor)

1998-01-01

Current NASA planning envisions human missions to Mars as early as 2013, on a mission that would send six crew members for a 500-day stay on the surface of Mars. While our understanding of how we would get there and back is fairly mature, the planning for what the crew would do to explore while on the surface for 500 days is less detailed. Mission objectives are to understand the composition and geo- morphology of the martian surface, and to continue to investigate and sample the geologic history of Mars. Special emphasis will focus on exploring for possible biogenic signatures, past or present, and on analyzing pre-biotic chemistry. The purpose of this workshop was to explore the strategies, desired capabilities, skills, and operational realities required to lend success to the first human missions to Mars. Current mission planning dictates that there will be considerable mobility, sampling and analytical capability available to human crews, at a site warranting long-term geologic and possibly biological interest. However, the details of specific capabilities are not yet clearly defined.

Mars Field Geology, Biology, and Paleontology Workshop: Summary and Recommendations

NASA Technical Reports Server (NTRS)

Budden, Nancy Ann (Editor)

1999-01-01

Current NASA planning envisions human missions to Mars as early as 2013, on a mission that would send six crew members for a 500-day stay on the surface of Mars. While our understanding of how we would get there and back is fairly mature, the planning for what the crew would do to explore while on the surface for 500 days is less detailed. Mission objectives are to understand the composition and geo- morphology of the martian surface, and to continue to investigate and sample the geologic history of Mars. Special emphasis will focus on exploring for possible biogenic signatures, past or present, and on analyzing pre-biotic chemistry. The purpose of this workshop was to explore the strategies, desired capabilities, skills, and operational realities required to lend success to the first human missions to Mars. Current mission planning dictates that there will be considerable mobility, sampling and analytical capability available to human crews, at a site warranting long-term geologic and possibly biological interest. However, the details of specific capabilities are not yet clearly defined.

FY07 LDRD Final Report A Fracture Mechanics and Tribology Approach to Understanding Subsurface Damage on Fused Silica during Grinding and Polishing

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

Suratwala, T I; Miller, P E; Menapace, J A

The objective of this work is to develop a solid scientific understanding of the creation and characteristics of surface fractures formed during the grinding and polishing of brittle materials, specifically glass. In this study, we have experimentally characterized the morphology, number density, and depth distribution of various surface cracks as a function of various grinding and polishing processes (blanchard, fixed abrasive grinding, loose abrasive, pitch polishing and pad polishing). Also, the effects of load, abrasive particle (size, distribution, foreign particles, geometry, velocity), and lap material (pitch, pad) were examined. The resulting data were evaluated in terms of indentation fracture mechanicsmore » and tribological interactions (science of interacting surfaces) leading to several models to explain crack distribution behavior of ground surfaces and to explain the characteristics of scratches formed during polishing. This project has greatly advanced the scientific knowledge of microscopic mechanical damage occurring during grinding and polishing and has been of general interest. This knowledge-base has also enabled the design and optimization of surface finishing processes to create optical surfaces with far superior laser damage resistance. There are five major areas of scientific progress as a result of this LDRD. They are listed in Figure 1 and described briefly in this summary below. The details of this work are summarized through a number of published manuscripts which are included this LDRD Final Report. In the first area of grinding, we developed a technique to quantitatively and statistically measure the depth distribution of surface fractures (i.e., subsurface damage) in fused silica as function of various grinding processes using mixtures of various abrasive particles size distributions. The observed crack distributions were explained using a model that extended known, single brittle indentation models to an ensemble of loaded, sliding particles. The model illustrates the importance of the particle size distribution of the abrasive and its influence on the resulting crack distribution. The results of these studies are summarized in references 1-7. In the second area of polishing, we conducted a series of experiments showing the influence of rogue particles (i.e., particles in the polishing slurry that are larger than base particles) on the creation of scratches on polished surfaces. Scratches can be thought of a as a specific type of sub-surface damage. The characteristics (width, length, type of fractures, concentration) were explained in terms of the rogue particle size, the rogue particle material, and the viscoelastic properties of the lap. The results of these studies are summarized in references 6-7. In the third area of etching, we conducted experiments aimed at understanding the effect of HF:NH{sub 4}F acid etching on surface fractures on fused silica. Etching can be used as a method: (a) to expose sub-surface mechanical damage, (b) to study the morphology of specific mechanical damage occurring by indentation, and (c) to convert a ground surface containing a high concentration of sub-surface mechanical damage into surface roughness. Supporting models have been developed to describe in detail the effect of etching on the morphology and evolution of surface cracks. The results of these studies are summarized in references 8-9. In the fourth area of scratch forensics or scratch fractography, a set of new scratch forensic rule-of-thumbs were developed in order to aid the optical fabricator and process engineer to interpret the cause of scratches and digs on surfaces. The details of how these rules were developed are described in each of the references included in this summary (1-9). Figure 2 provides as a summary of some of the more commonly used rules-of-thumbs that have been developed in this study. In the fifth and final area of laser damage, we demonstrated that the removal of such surface fractures from the surface during optical fabrication can dramatically improve the laser damage.« less

Cu self-sputtering MD simulations for 0.1-5 keV ions at elevated temperatures

NASA Astrophysics Data System (ADS)

Metspalu, Tarvo; Jansson, Ville; Zadin, Vahur; Avchaciov, Konstantin; Nordlund, Kai; Aabloo, Alvo; Djurabekova, Flyura

2018-01-01

Self-sputtering of copper under high electric fields is considered to contribute to plasma buildup during a vacuum breakdown event frequently observed near metal surfaces, even in ultra high vacuum condition in different electric devices. In this study, by means of molecular dynamics simulations, we analyze the effect of surface temperature and morphology on the yield of self-sputtering of copper with ion energies of 0.1-5 keV. We analyze all three low-index surfaces of Cu, {1 0 0}, {1 1 0} and {1 1 1}, held at different temperatures, 300 K, 500 K and 1200 K. The surface roughness relief is studied by either varying the angle of incidence on flat surfaces, or by using arbitrary roughened surfaces, which result in a more natural distribution of surface relief variations. Our simulations provide detailed characterization of copper self-sputtering with respect to different material temperatures, crystallographic orientations, surface roughness, energies, and angles of ion incidence.

Study on the formation of dodecagonal pyramid on nitrogen polar GaN surface etched by hot H3PO4

NASA Astrophysics Data System (ADS)

Qi, S. L.; Chen, Z. Z.; Fang, H.; Sun, Y. J.; Sang, L. W.; Yang, X. L.; Zhao, L. B.; Tian, P. F.; Deng, J. J.; Tao, Y. B.; Yu, T. J.; Qin, Z. X.; Zhang, G. Y.

2009-08-01

Hot phosphor acid (H3PO4) etching is presented to form a roughened surface with dodecagonal pyramids on laser lift-off N face GaN grown by metalorganic chemical vapor deposition. A detailed analysis of time evolution of surface morphology is described as a function of etching temperature. The activation energy of the H3PO4 etching process is 1.25 eV, indicating the process is reaction-limited scheme. And it is found that the oblique angle between the facets and the base plane increases as the temperature increases. Thermodynamics and kinetics related factors of the formation mechanism of the dodecagonal pyramid are also discussed. The light output power of a vertical injection light-emitting-diode (LED) with proper roughened surface shows about 2.5 fold increase compared with that of LED without roughened surface.

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

Checco, A.; Hofmann, T.; DiMasi, E.

The details of air nanobubble trapping at the interface between water and a nanostructured hydrophobic silicon surface are investigated using X-ray scattering and contact angle measurements. Large-area silicon surfaces containing hexagonally packed, 20 nm wide hydrophobic cavities provide ideal model surfaces for studying the morphology of air nanobubbles trapped inside cavities and its dependence on the cavity depth. Transmission small-angle X-ray scattering measurements show stable trapping of air inside the cavities with a partial water penetration of 5-10 nm into the pores, independent of their large depth variation. This behavior is explained by consideration of capillary effects and the cavitymore » geometry. For parabolic cavities, the liquid can reach a thermodynamically stable configuration - a nearly planar nanobubble meniscus - by partially penetrating into the pores. This microscopic information correlates very well with the macroscopic surface wetting behavior.« less

Low Dimensional Analysis of Wing Surface Morphology in Hummingbird Free Flight

NASA Astrophysics Data System (ADS)

Shallcross, Gregory; Ren, Yan; Liu, Geng; Dong, Haibo; Tobalske, Bret

2015-11-01

Surface morphing in flapping wings is a hallmark of bird flight. In current work, the role of dynamic wing morphing of a free flying hummingbird is studied in detail. A 3D image-based surface reconstruction method is used to obtain the kinematics and deformation of hummingbird wings from high-quality high-speed videos. The observed wing surface morphing is highly complex and a number of modeling methods including singular value decomposition (SVD) are used to obtain the fundamental kinematical modes with distinct motion features. Their aerodynamic roles are investigated by conducting immersed-boundary-method based flow simulations. The results show that the chord-wise deformation modes play key roles in the attachment of leading-edge vortex, thus improve the performance of the flapping wings. This work is supported by NSF CBET-1313217 and AFOSR FA9550-12-1-0071.

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.

In situ atomic force microscopy analysis of morphology and particle size changes in lithium iron phosphate cathode during discharge.

PubMed

Demirocak, Dervis Emre; Bhushan, Bharat

2014-06-01

Li-ion batteries offer great promise for future plug-in hybrid electric vehicles (PHEVs) and pure electric vehicles (EVs). One of the challenges is to improve the cycle life of Li-ion batteries which requires detailed understanding of the aging phenomenon. In situ techniques are especially valuable to understand aging since it allows monitoring the physical and chemical changes in real time. In this study, in situ atomic force microscopy (AFM) is utilized to study the changes in morphology and particle size of LiFePO4 cathode during discharge. The guidelines for in situ AFM cell design for accurate and reliable measurements based on different designs are presented. The effect of working electrode to counter electrode surface area ratio on cycling data of an in situ cell is also discussed. Analysis of the surface area change in LiFePO4 particles when the cell was cycled between 100% and 70% state of charge is presented. Among four particles analyzed, surface area increase of particles during Li intercalation of LiFePO4 spanned from 1.8% to 14.3% indicating the inhomogeneous nature of the cathode surface. Copyright © 2014 Elsevier Inc. All rights reserved.

Deuterium desorption from ion-irradiated tantalum and effects on surface morphology

NASA Astrophysics Data System (ADS)

Novakowski, T. J.; Sundaram, A.; Tripathi, J. K.; Gonderman, S.; Hassanein, A.

2018-06-01

Compared to tungsten (W), tantalum (Ta) has shown superior resistance to helium (He)-induced surface morphology changes under fusion-relevant irradiation conditions. However, Ta is also expected to have a stronger interaction with hydrogen isotopes, potentially limiting its use as a plasma-facing material. Despite these concerns, detailed investigations on hydrogen irradiation effects on Ta are scarce. In this study, pristine and fuzzy (He+ ion-irradiated) Ta samples are irradiated with 120 eV deuterium (D) ions at various temperatures and examined with a combination of thermal desorption spectroscopy (TDS), scanning electron microscopy (SEM), and optical reflectivity. TDS reveals discrete D desorption temperatures at 660 and 760 K, corresponding to trapping energies of 1.82 and 2.11 eV, respectively. Although D is retained in Ta both in higher quantities and at higher temperatures compared to W, extreme surface temperatures expected in tokamak divertors may exceed these desorption temperatures and counteract retention. Furthermore, this study indicates that Ta is relatively resistant to adverse surface structuring under D+ ion irradiation. In fact, D+ is shown to prevent and suppress Ta fuzz formation in sequential D+/He+ ion irradiation experiments. While further investigations are needed to elucidate this behavior, these initial investigations show a strong potential for the use of Ta as a PFC material.

Quaternary geomorphology and modern coastal development in response to an inherent geologic framework: An example from Charleston, South Carolina

USGS Publications Warehouse

Harris, M.S.; Gayes, P.T.; Kindinger, J.L.; Flocks, J.G.; Krantz, D.E.; Donovan, P.

2005-01-01

Coastal landscapes evolve over wide-ranging spatial and temporal scales in response to physical and biological pro-cesses that interact with a wide range of variables. To develop better predictive models for these dynamic areas, we must understand the influence of these variables on coastal morphologies and ultimately how they influence coastal processes. This study defines the influence of geologic framework variability on a classic mixed-energy coastline, and establishes four categorical scales of spatial and temporal influence on the coastal system. The near-surface, geologic framework was delineated using high-resolution seismic profiles, shallow vibracores, detailed geomorphic maps, historical shorelines, aerial photographs, and existing studies, and compared to the long- and short-term development of two coastal compartments near Charleston, South Carolina. Although it is clear that the imprint of a mixed-energy tidal and wave signal (basin-scale) dictates formation of drumstick barriers and that immediate responses to wave climate are dramatic, island size, position, and longer-term dynamics are influenced by a series of inherent, complex near-surface stratigraphic geometries. Major near-surface Tertiary geometries influence inlet placement and drainage development (island-scale) through multiple interglacial cycles and overall channel morphology (local-scale). During the modern marine transgression, the halo of ebb-tidal deltas greatly influence inlet region dynamics, while truncated beach ridges and exposed, differentially erodable Cenozoic deposits in the active system influence historical shoreline dynamics and active shoreface morphologies (blockscale). This study concludes that the mixed-energy imprint of wave and tide theories dominates general coastal morphology, but that underlying stratigraphic influences on the coast provide site-specific, long-standing imprints on coastal evolution.

Data on the detail information of influence of substrate temperature on the film morphology and photovoltaic performance of non-fullerene organic solar cells.

PubMed

Zhang, Jicheng; Xie, SuFei; Lu, Zhen; Wu, Yang; Xiao, Hongmei; Zhang, Xuejuan; Li, Guangwu; Li, Cuihong; Chen, Xuebo; Ma, Wei; Bo, Zhishan

2017-10-01

This data contains additional data related to the article "Influence of Substrate Temperature on the Film Morphology and Photovoltaic Performance of Non-fullerene Organic Solar Cells" (Jicheng Zhang et al., In press) [1]. Data include measurement and characterization instruments and condition, detail condition to fabricate norfullerene solar cell devices, hole-only and electron-only devices. Detail condition about how to control the film morphology of devices via tuning the temperature of substrates was also displayed. More information and more convincing data about the change of film morphology for active layers fabricated from different temperature, which is attached to the research article of "Influence of Substrate Temperature on the Film Morphology and Photovoltaic Performance of Non-fullerene Organic Solar Cells" was given.

What does nitric acid really do to carbon nanofibers? [What nitric acid really does to carbon nanofibers

DOE PAGES

Sainio, S.; Nordlund, D.; Gandhiraman, R.; ...

2016-09-15

Understanding the chemical nature of the surface of carbon nanofibers (CNF) is critical in assessing their fundamental properties and tailoring them for the right application. To gain such knowledge, we present here a detailed X-ray adsorption spectroscopy (XAS) study accompanied by high resolution transmission electron microscopy (TEM) micrographs of two morphologically different CNF pairs (tetrahedral amorphous carbon (ta-C) grown “open structured” fibers and traditional bamboo-like “closed structured” fibers), where the surface chemical properties and structural features of the fibers are investigated in depth and the effects of nitric acid treatment on the fibers are revealed. The morphology of the fibermore » and/or the original seed- and adhesion layers markedly affect the response of the fibers to the acid treatment. Results also show that the nitric acid treatment increases the observed sp 2 intensity and modifies the two types of fibers to become more-alike both structurally and with respect to their oxygen functionalities. Furthermore, the XAS and HRTEM results confirm that a short nitric acid treatment does not remove the Ni catalyst particle but, instead, oxidizes their surfaces, especially in the case of ta-C grown fibers.« less

What does nitric acid really do to carbon nanofibers? [What nitric acid really does to carbon nanofibers

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

Sainio, S.; Nordlund, D.; Gandhiraman, R.

Understanding the chemical nature of the surface of carbon nanofibers (CNF) is critical in assessing their fundamental properties and tailoring them for the right application. To gain such knowledge, we present here a detailed X-ray adsorption spectroscopy (XAS) study accompanied by high resolution transmission electron microscopy (TEM) micrographs of two morphologically different CNF pairs (tetrahedral amorphous carbon (ta-C) grown “open structured” fibers and traditional bamboo-like “closed structured” fibers), where the surface chemical properties and structural features of the fibers are investigated in depth and the effects of nitric acid treatment on the fibers are revealed. The morphology of the fibermore » and/or the original seed- and adhesion layers markedly affect the response of the fibers to the acid treatment. Results also show that the nitric acid treatment increases the observed sp 2 intensity and modifies the two types of fibers to become more-alike both structurally and with respect to their oxygen functionalities. Furthermore, the XAS and HRTEM results confirm that a short nitric acid treatment does not remove the Ni catalyst particle but, instead, oxidizes their surfaces, especially in the case of ta-C grown fibers.« less

Detailed surface morphology of the 'lobster louse' copepod, Nicothoë astaci, a haematophagous gill parasite of the European lobster, Homarus gammarus.

PubMed

Davies, Charlotte E; Thomas, Gethin R; Maffeis, Thierry G G; Wootton, Emma C; Penny, Mark W; Rowley, Andrew F

2014-10-01

The ectoparasitic copepod, Nicothoë astaci (the 'lobster louse'), infests the gills of the European lobster, Homarus gammarus. There have been limited studies on this haematophagous species; therefore knowledge of this parasite is rudimentary. The current study examines the surface morphology of this parasitic copepod, detached from the host, concentrating on adaptations of the suctorial mouthpart, the oral disc. Cryo-scanning electron microscopy revealed structural adaptations that facilitate attachment of these parasites to the gill filaments of their lobster host. The aperture of the feeding channel, through which host haemolymph is drawn, is only ca. 5μm in diameter. The edge of the oral disc is lined with numerous setae, whilst the surface of the disc is covered with large numbers of small (<1μm in diameter) teeth-like structures, which presumably pierce through, and grip, the cuticle lining of the host's gill. Overall, these structures are thought to provide a 'vacuum seal' to assist in pumping of blood, via peristalsis, into the alimentary canal of the copepod host. Copyright © 2014 Elsevier Inc. All rights reserved.

Controlling Growth Orientation of Phthalocyanine Films by Electrical Fields

NASA Technical Reports Server (NTRS)

Zhu, S.; Banks, C. E.; Frazier, D. O.; Ila, D.; Muntele, I.; Penn, B. G.; Sharma, A.; Rose, M. Franklin (Technical Monitor)

2001-01-01

Organic Phthalocyanine films have many applications ranging from data storage to various non-linear optical devices whose quality is affected by the growth orientation of Phthalocyanine films. Due to the structural and electrical properties of Phthalocyanine molecules, the film growth orientation depends strongly on the substrate surface states. In this presentation, an electrical field up to 4000 V/cm is introduced during film growth. The Phthalocyanine films are synthesized on quartz substrates using thermal evaporation. An intermediate layer is deposited on some substrates for introducing the electrical field. Scanning electron microscopy, x-ray diffraction, and Fourier transform infrared spectroscopy are used for measuring surface morphology, film structure, and optical properties, respectively. The comparison of Phthalocyanine films grown with and without the electrical field reveals different morphology, film density, and growth orientation, which eventually change optical properties of these films. These results suggest that the growth method in the electrical field can be used to synthesized Phthalocyanine films with a preferred crystal orientation as well as propose an interaction mechanism between the substrate surface and the depositing molecules. The details of growth conditions and of the growth model of how the Phthalocyanine molecules grow in the electrical field will be discussed.

Ultrafast laser induced periodic sub-wavelength aluminum surface structures and nanoparticles in air and liquids

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

Kuladeep, Rajamudili; Dar, Mudasir H.; Rao, D. Narayana, E-mail: dnrsp@uohyd.ac.in, E-mail: dnr-laserlab@yahoo.com

2014-09-21

In this communication, we demonstrate the generation of laser-induced periodic sub-wavelength surface structures (LIPSS) or ripples on a bulk aluminum (Al) and Al nanoparticles (NPs) by femtosecond (fs) laser direct writing technique. Laser irradiation was performed on Al surface at normal incidence in air and by immersing in ethanol (C₂H₅OH) and water (H₂O) using linearly polarized Ti:sapphire fs laser pulses of ~110 fs pulse duration and ~800 nm wavelength. Field emission scanning electron microscope is utilized for imaging surface morphology of laser written structures and it reveals that the spatial periodicity as well as the surface morphology of the LIPSSmore » depends on the surrounding dielectric medium and also on the various laser irradiation parameters. The observed LIPSS have been classified as low spatial frequency LIPSS which are perpendicularly oriented to the laser polarization with a periodicity from 460 to 620 nm and high spatial frequency LIPSS which spectacles a periodicity less than 100 nm with the orientation parallel to the polarization of the incident laser beam. Fabricated colloidal solutions, which contain the Al NPs, were characterized by UV-Vis absorption spectroscopy and transmission electron microscopy (TEM). TEM results reveal the formation of internal cavities in Al NPs both in ethanol and water. Formation mechanism of LIPSS and cavities inside the nanoparticles are discussed in detail.« less

A morphologically preserved multi-resolution TIN surface modeling and visualization method for virtual globes

NASA Astrophysics Data System (ADS)

Zheng, Xianwei; Xiong, Hanjiang; Gong, Jianya; Yue, Linwei

2017-07-01

Virtual globes play an important role in representing three-dimensional models of the Earth. To extend the functioning of a virtual globe beyond that of a "geobrowser", the accuracy of the geospatial data in the processing and representation should be of special concern for the scientific analysis and evaluation. In this study, we propose a method for the processing of large-scale terrain data for virtual globe visualization and analysis. The proposed method aims to construct a morphologically preserved multi-resolution triangulated irregular network (TIN) pyramid for virtual globes to accurately represent the landscape surface and simultaneously satisfy the demands of applications at different scales. By introducing cartographic principles, the TIN model in each layer is controlled with a data quality standard to formulize its level of detail generation. A point-additive algorithm is used to iteratively construct the multi-resolution TIN pyramid. The extracted landscape features are also incorporated to constrain the TIN structure, thus preserving the basic morphological shapes of the terrain surface at different levels. During the iterative construction process, the TIN in each layer is seamlessly partitioned based on a virtual node structure, and tiled with a global quadtree structure. Finally, an adaptive tessellation approach is adopted to eliminate terrain cracks in the real-time out-of-core spherical terrain rendering. The experiments undertaken in this study confirmed that the proposed method performs well in multi-resolution terrain representation, and produces high-quality underlying data that satisfy the demands of scientific analysis and evaluation.

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

Effect of Micro- and Nanoscale Topography on the Adhesion of Bacterial Cells to Solid Surfaces

PubMed Central

Hsu, Lillian C.; Fang, Jean; Borca-Tasciuc, Diana A.; Worobo, Randy W.

2013-01-01

Attachment and biofilm formation by bacterial pathogens on surfaces in natural, industrial, and hospital settings lead to infections and illnesses and even death. Minimizing bacterial attachment to surfaces using controlled topography could reduce the spreading of pathogens and, thus, the incidence of illnesses and subsequent human and financial losses. In this context, the attachment of key microorganisms, including Escherichia coli, Listeria innocua, and Pseudomonas fluorescens, to silica and alumina surfaces with micron and nanoscale topography was investigated. The results suggest that orientation of the attached cells occurs preferentially such as to maximize their contact area with the surface. Moreover, the bacterial cells exhibited different morphologies, including different number and size of cellular appendages, depending on the topographical details of the surface to which they attached. This suggests that bacteria may utilize different mechanisms of attachment in response to surface topography. These results are important for the design of novel microbe-repellant materials. PMID:23416997

The application of X-ray microtomography for the assessement of root resorption caused by the orthodontic treatment of premolars.

PubMed

Sawicka, Monika; Bedini, Rossella; Pecci, Raffaella; Pameijer, Cornelis Hans; Kmiec, Zbigniew

2012-01-01

The purpose of this study was to demonstrate potential application of micro-computed tomography in the morphometric analysis of the root resorption in extracted human first premolars subjected to the orthodontic force. In one patient treated in the orthodontic clinic two mandibular first premolars subjected to orthodontic force for 4 weeks and one control tooth were selected for micro-computed tomographic analysis. The hardware device used in this study was a desktop X-ray microfocus CT scanner (SkyScan 1072). The morphology of root's surfaces was assessed by TView and Computer Tomography Analyzer (CTAn) softwares (SkyScan, bvba) which allowed analysis of all microscans, identification of root resorption craters and measurement of their length, width and volume. Microscans showed in details the surface morphology of the investigated teeth. The analysis of microscans allowed to detect 3 root resorption cavities in each of the orthodontically moved tooth and only one resorption crater in the control tooth. The volumes of the resorption craters in orthodontically-treated teeth were much larger than in a control tooth. Micro-computed tomography is a reproducible technique for the three-dimensional non-invasive assessment of root's morphology ex vivo. TView and CTan softwares are useful in accurate morphometric measurements of root's resorption.

Characteristics and in vitro response of thin hydroxyapatite–titania films produced by plasma electrolytic oxidation of Ti alloys in electrolytes with particle additions

PubMed Central

Yeung, W. K.; Sukhorukova, I. V.; Shtansky, D. V.; Levashov, E. A.; Zhitnyak, I. Y.; Gloushankova, N. A.; Kiryukhantsev-Korneev, P. V.; Petrzhik, M. I.; Matthews, A.

2016-01-01

The enhancement of the biological properties of Ti by surface doping with hydroxyapatite (HA) is of great significance, especially for orthodontic applications. This study addressed the effects of HA particle size in the electrolyte suspension on the characteristics and biological properties of thin titania-based coatings produced on Ti–6Al–4V alloy by plasma electrolytic oxidation (PEO). Detailed morphological investigation of the coatings formed by a single-stage PEO process with two-step control of the electrical parameters was performed using the Minkowski functionals approach. The surface chemistry was studied by glow discharge optical emission spectroscopy and Fourier transform infrared spectroscopy, whereas mechanical properties were evaluated using scratch tests. The biological assessment included in vitro evaluation of the coating bioactivity in simulated body fluid (SBF) as well as studies of spreading, proliferation and osteoblastic differentiation of MC3T3-E1 cells. The results demonstrated that both HA micro- and nanoparticles were successfully incorporated in the coatings but had different effects on their surface morphology and elemental distributions. The micro-particles formed an irregular surface morphology featuring interpenetrated networks of fine pores and coating material, whereas the nanoparticles penetrated deeper into the coating matrix which retained major morphological features of the porous TiO2 coating. All coatings suffered cohesive failure in scratch tests, but no adhesive failure was observed; moreover doping with HA increased the coating scratch resistance. In vitro tests in SBF revealed enhanced bioactivity of both HA-doped PEO coatings; furthermore, the cell proliferation/morphometric tests showed their good biocompatibility. Fluorescence microscopy revealed a well-organised actin cytoskeleton and focal adhesions in MC3T3-E1 cells cultivated on these substrates. The cell alkaline phosphatase activity in the presence of ascorbic acid and β-glycerophosphate was significantly increased, especially in HA nanoparticle-doped coatings. PMID:27019704

Morphological evolution and characterization of GaN pyramid arrays fabricated by photo-assisted chemical etching

NASA Astrophysics Data System (ADS)

Zhang, Shiying; Xiu, Xiangqian; Xu, Qingjun; Li, Yuewen; Hua, Xuemei; Chen, Peng; Xie, Zili; Liu, Bin; Zhou, Yugang; Han, Ping; Zhang, Rong; Zheng, Youdou

2016-12-01

GaN pyramid arrays have been successfully synthesized by selective photo-assisted chemical etching in a K2S2O8/KOH solution. A detailed analysis of time evolution of surface morphology has been conducted, which describes an etching process of GaN pyramids. Room temperature cathodoluminescence images indicate that these pyramids are composed of crystalline GaN surrounding dislocations, which is caused by the greater recombination rate of electrons and holes at dislocation than that of crystalline GaN. The Raman results show a stress relaxation in GaN pyramids compared with unetched GaN. The optical property of both unetched GaN and GaN pyramids has been studied by photoluminescence. The formation mechanism and feature of GaN pyramids are also rationally explained.

Combustion synthesis and structural analysis of nanocrystalline nickel ferrite at low temperature regime

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

Shanmugavel, T., E-mail: gokulrajs@hotmail.com, E-mail: shanmugavelnano@gmail.com; Raj, S. Gokul, E-mail: gokulrajs@hotmail.com, E-mail: shanmugavelnano@gmail.com; Rajarajan, G.

2015-06-24

Combustion synthesis of single phase Nickel ferrite was successfully achieved at low temperature regime. The obtained powders were calcinated to increase the crystallinity and their characterization change due to calcinations is investigated in detail. Citric acid used as a chelating agent for the synthesis of nickel ferrite. Pure single phase nickel ferrites were found at this low temperature. The average crystalline sizes were measured by using powder XRD measurements. Surface morphology was investigated through Transmission Electron Microscope (TEM). Particle size calculated in XRD is compared with TEM results. Magnetic behaviour of the samples is analyzed by using Vibrating Sample Magnetometermore » (VSM). Saturation magnetization, coercivity and retentivity are measured and their results are discussed in detail.« less

The geology and geophysics of Mars

NASA Technical Reports Server (NTRS)

Saunders, R. S.

1976-01-01

The current state of knowledge concerning the regional geology and geophysics of Mars is summarized. Telescopic observations of the planet are reviewed, pre-Mariner models of its interior are discussed, and progress achieved with the Mariner flybys, especially that of Mariner 9, is noted. A map of the Martian geological provinces is presented to provide a summary of the surface geology and morphology. The contrast between the northern and southern hemispheres is pointed out, and the characteristic features of the surface are described in detail. The global topography of the planet is examined along with its gravitational field, gravity anomalies, and moment of inertia. The general sequence of events in Martian geological history is briefly outlined.

Lunar apennine-hadley region: geological inplications of Earth-based radar and infrared measurements.

PubMed

Zisk, S H; Carr, M H; Masursky, H; Shorthill, R W; Thompson, T W

1971-08-27

Recently completed high-resolution radar maps of the moon contain information on the decimeter-scale structure of the surface. When this information is combined with eclipse thermal-enhancement data and with high-resolution Lunar Orbiter photography, the surface morphology is revealed in some detail. A geological history for certain features and subareas can be developed, which provides one possible framework for the interpretation of the findings from the Apollo 15 landing. Frequency of decimeter-and meter-size blocks in and around lunar craters, given by the remote-sensed data, supports a multilayer structure in the Palus Putredinis mare region, as well as a great age for the bordering Apennine Mountains scarp.

Lunar Apennine-Hadley region: Geological implications of earth-based radar and infrared measurements

USGS Publications Warehouse

Zisk, S.H.; Carr, M.H.; Masursky, H.; Shorthill, R.W.; Thompson, T.W.

1971-01-01

Recently completed high-resolution radar maps of the moon contain information on the decimeter-scale structure of the surface. When this information is combined with eclipse thermal-enhancement data and with high-resolution Lunar Orbiter photography, the surface morphology is revealed in some detail. A geological history for certain features and subareas can be developed, which provides one possible framework for the interpretation of the findings from the Apollo 15 landing. Frequency of decimeter- and meter-size blocks in and around lunar craters, given by the remote-sensed data, supports a multilayer structure in the Palus Putredinis mare region, as well as a great age for the bordering Apennins Mountains scarp.

A simplified plastic embedding and immunohistologic technique for immunophenotypic analysis of human hematopoietic and lymphoid tissues.

PubMed Central

Casey, T. T.; Cousar, J. B.; Collins, R. D.

1988-01-01

Routine fixation and paraffin embedding destroys many hematopoietic and lymphoid differentiation antigens detected by flow cytometry or frozen section immunohistochemistry. On the other hand, morphologic evaluation is difficult in flow cytometric or frozen section studies. A simplified three-step plastic embedding system using acetone-fixed tissues embedded in glycol-methacrylate (GMA) resin has been found to provide both excellent morphologic and antigenic preservation. With our system, a wide variety of antigens are detected in plastic sections without trypsinization or prolonged embedding procedures; pan-B (CD19, CD22), pan-T (CD7, CD5, CD3, CD2), T-subset (CD4, CD8, CD1, CD25) markers as well as surface immunoglobulin and markers for myeloid and mononuclear-phagocyte cells are preserved. In summary, modifications of plastic embedding techniques used in this study simplify the procedure, apparently achieve excellent antigenic preservation, and facilitate evaluation of morphologic details in relation to immunocytochemical markers. Images Figure 1 Figure 2 Figure 3 Figure 4 Figure 5 PMID:3282442

Gold-Gilded Zinc Oxide Nanodiamonds: Plasmonic and Morphological Effects

NASA Astrophysics Data System (ADS)

Khan, G. R.; Khan, R. A.

The novel properties, diverse applications and device performance of nanocomposites can be greatly modulated through astute combination of plasmonic and morphological effects. The biosensing sensitivity, semiconducting capability, photocatalytic efficiency and antibacterial efficacy of ZnO nanostructures can be enhanced by a diamond-like morphology of ZnO via incorporation of plasmonic gold owing to their exceptional specific surface area, outstanding photoluminescence and excellent biocompatibility. Toward the realization of this goal, Au-Zno nanodiamonds have been successfully synthesized by a microwave assisted solution phase route without use of any costly solvents, surfactants, substrates, post-synthesis treatment or hazardous ingredients. It shows the ability to control the concentration of Au nanoparticles in ZnO and the evolution of its growth in diamond shape. The synthesized nanocomposites were characterized by high-resolution measurements such as transmission electron microscopy (TEM), diffused reflectance spectroscopy (DRS), energy dispersive X-ray spectroscopy (EDX), X-ray diffractometory (XRD), Raman spectroscopy and Fourier transform infrared spectroscopy (FT-IR), and the results discussed in detail.

Controls on morphometry and morphology of alluvial and colluvial fans in the high-Arctic setting, Petuniabukta, Svalbard.

NASA Astrophysics Data System (ADS)

Tomczyk, Aleksandra; Ewertowski, Marek

2016-04-01

The Petuniabukta (78o42' N, 16o32') is a bay in the northern part of Billefjorden in the central part of Spitsbergen Island, Svalbard. The bay is surrounded by six major, partly glaciated valleys. A numerous alluvial and colluvial fans have developed within valleys as well as along the fiord margins. Distribution and characterization of morphometric parameters of fans were investigated using time-series of orthophotos and digital elevation models (generated based on 1961, 1990, 2009 aerial photographs) and high resolution satellite imagery from 2013. In addition, a very detailed DEM and orthophoto (5 cm resolution) have been produced from unmanned aerial vehicle (UAV) imagery from 2014 and 2015, covering three fans characterised by different types of surface morphology. A 1:40,000 map showing the distribution of almost 300 alluvial and colluvial fans (ranging in area from 325 km2 to 451 275 km2), together with time-series of 1:5,000 geomorphological maps of sample fans enabled an assessment of the spatial and temporal evolution of processes responsible for delivery and erosion of sediments from the fans. The relationship between terrain parameters (e.g. slope, exposition) as well as geology was also investigated. Many of the studied alluvial fans were at least partly coupled and sediments were transferred from the upstream zone to the downstream zone, either due to debris-flow or channelized stream flow. In other cases, coarse sediments were stored within fans, and fines were transported downstream by sheet flows or sub-surface flows. In most of smaller colluvial fans and debris cones, sediments were delivered by mass movement processes (mainly rockfalls and snowfalls) and did not reach lower margin of landforms. Analysis of historical aerial photographs indicated recent increase in the activity of debris-flow modification of surface morphology of fans. Fans located outside limits of the Little Ice Age (LIA) glaciation are dominated by the secondary processes, which do not cause significant aggradation, but can substantially modified surface morphology. In contrary, surface morphology of fans located inside the limits of the LIA glaciation and along contemporary glaciers is dominated by the primary processes of deposition. The research was founded by the Polish National Science Centre.

TOPICAL REVIEW: Electrowetting: from basics to applications

NASA Astrophysics Data System (ADS)

Mugele, Frieder; Baret, Jean-Christophe

2005-07-01

Electrowetting has become one of the most widely used tools for manipulating tiny amounts of liquids on surfaces. Applications range from 'lab-on-a-chip' devices to adjustable lenses and new kinds of electronic displays. In the present article, we review the recent progress in this rapidly growing field including both fundamental and applied aspects. We compare the various approaches used to derive the basic electrowetting equation, which has been shown to be very reliable as long as the applied voltage is not too high. We discuss in detail the origin of the electrostatic forces that induce both contact angle reduction and the motion of entire droplets. We examine the limitations of the electrowetting equation and present a variety of recent extensions to the theory that account for distortions of the liquid surface due to local electric fields, for the finite penetration depth of electric fields into the liquid, as well as for finite conductivity effects in the presence of AC voltage. The most prominent failure of the electrowetting equation, namely the saturation of the contact angle at high voltage, is discussed in a separate section. Recent work in this direction indicates that a variety of distinct physical effects—rather than a unique one—are responsible for the saturation phenomenon, depending on experimental details. In the presence of suitable electrode patterns or topographic structures on the substrate surface, variations of the contact angle can give rise not only to continuous changes of the droplet shape, but also to discontinuous morphological transitions between distinct liquid morphologies. The dynamics of electrowetting are discussed briefly. Finally, we give an overview of recent work aimed at commercial applications, in particular in the fields of adjustable lenses, display technology, fibre optics, and biotechnology-related microfluidic devices.

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.

Monitoring Demineralization and Subsequent Remineralization of Human Teeth at the Dentin-Enamel Junction with Atomic Force Microscopy.

PubMed

Lechner, Bob-Dan; Röper, Stephanie; Messerschmidt, Jens; Blume, Alfred; Magerle, Robert

2015-09-02

Using atomic force microscopy, we monitored the nanoscale surface morphology of human teeth at the dentin-enamel junction after performing successive demineralization steps with an acidic soft drink. Subsequently, we studied the remineralization process with a paste containing calcium and phosphate ions. Repeated atomic force microscopy imaging of the same sample areas on the sample allowed us to draw detailed conclusions regarding the specific mechanism of the demineralization process and the subsequent remineralization process. The about 1-μm-deep grooves that are caused by the demineralization process were preferentially filled with deposited nanoparticles, leading to smoother enamel and dentine surfaces after 90 min exposure to the remineralizing agent. The deposited material is found to homogeneously cover the enamel and dentine surfaces in the same manner. The temporal evolution of the surface roughness indicates that the remineralization caused by the repair paste proceeds in two distinct successive phases.

3D-printing of undisturbed soil imaged by X-ray

NASA Astrophysics Data System (ADS)

Bacher, Matthias; Koestel, John; Schwen, Andreas

2014-05-01

The unique pore structures in Soils are altered easily by water flow. Each sample has a different morphology and the results of repetitions vary as well. Soil macropores in 3D-printed durable material avoid erosion and have a known morphology. Therefore potential and limitations of reproducing an undisturbed soil sample by 3D-printing was evaluated. We scanned an undisturbed soil column of Ultuna clay soil with a diameter of 7 cm by micro X-ray computer tomography at a resolution of 51 micron. A subsample cube of 2.03 cm length with connected macropores was cut out from this 3D-image and printed in five different materials by a 3D-printing service provider. The materials were ABS, Alumide, High Detail Resin, Polyamide and Prime Grey. The five print-outs of the subsample were tested on their hydraulic conductivity by using the falling head method. The hydrophobicity was tested by an adapted sessile drop method. To determine the morphology of the print-outs and compare it to the real soil also the print-outs were scanned by X-ray. The images were analysed with the open source program ImageJ. The five 3D-image print-outs copied from the subsample of the soil column were compared by means of their macropore network connectivity, porosity, surface volume, tortuosity and skeleton. The comparison of pore morphology between the real soil and the print-outs showed that Polyamide reproduced the soil macropore structure best while Alumide print-out was the least detailed. Only the largest macropore was represented in all five print-outs. Printing residual material or printing aid material remained in and clogged the pores of all print-out materials apart from Prime Grey. Therefore infiltration was blocked in these print-outs and the materials are not suitable even though the 3D-printed pore shapes were well reproduced. All of the investigated materials were insoluble. The sessile drop method showed angles between 53 and 85 degrees. Prime Grey had the fastest flow rate; the other conducting materials had slow or non-reproducible flow rates. Since only Prime Grey was able to print-out the largest macropore in a discontinuous way, the morphological differences between the five print-outs were not evaluated. Each material has its limitations but only Prime Greys morphology was sufficiently printed and no clogging with residual material occurred. Polyamide and High Detail Resin had clogged pores but were matching the soil's macropore morphology better but further research on removal of residual material blocking pores is needed before they are useable.

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.

Diagnostics of microwave assisted electron cyclotron resonance plasma source for surface modification of nylon 6

NASA Astrophysics Data System (ADS)

More, Supriya E.; Das, Partha Sarathi; Bansode, Avinash; Dhamale, Gayatri; Ghorui, S.; Bhoraskar, S. V.; Sahasrabudhe, S. N.; Mathe, Vikas L.

2018-01-01

Looking at the increasing scope of plasma processing of materials surface, here we present the development and diagnostics of a microwave assisted Electron Cyclotron Resonance (ECR) plasma system suitable for surface modification of polymers. Prior to the surface-treatment, a detailed diagnostic mapping of the plasma parameters throughout the reactor chamber was carried out by using single and double Langmuir probe measurements in Ar plasma. Conventional analysis of I-V curves as well as the elucidation form of the Electron Energy Distribution Function (EEDF) has become the source of calibration of plasma parameters in the reaction chamber. The high energy tail in the EEDF of electron temperature is seen to extend beyond 60 eV, at much larger distances from the ECR zone. This proves the suitability of the rector for plasma processing, since the electron energy is much beyond the threshold energy of bond breaking in most of the polymers. Nylon 6 is used as a representative candidate for surface processing in the presence of Ar, H2 + N2, and O2 plasma, treated at different locations inside the plasma chamber. In a typical case, the work of adhesion is seen to almost get doubled when treated with oxygen plasma. Morphology of the plasma treated surface and its hydrophilicity are discussed in view of the variation in electron density and electron temperature at these locations. Nano-protrusions arising from plasma treatment are set to be responsible for the hydrophobicity. Chemical sputtering and physical sputtering are seen to influence the surface morphology on account of sufficient electron energies and increased plasma potential.

Influence of Microstructure on the Electrical Properties of Heteroepitaxial TiN Films

NASA Astrophysics Data System (ADS)

Xiang, Wenfeng; Liu, Yuan; Zhang, Jiaqi

2018-05-01

Heteroepitaxial TiN films were deposited on Si substrates by pulse laser deposition at different substrate temperature. The microstructure and surface morphology of the films were investigated by X-ray diffraction (θ-2θ scan, ω-scan, and ϕ-scan) and atomic force microscopy. The electrical properties of the prepared TiN films were studied using a physical property measurement system. The experimental results showed that the crystallinity and surface morphology of the TiN films were improved gradually with increasing substrate temperature below 700 °C. Specially, single crystal TiN films were prepared when substrate temperature is above 700 °C; However, the quality of TiN films gradually worsened when the substrate temperature was increased further. The electrical properties of the films were directly correlated to their crystalline quality. At the optimal substrate temperature of 700 °C, the TiN films exhibited the lowest resistivity and highest mobility of 25.7 μΩ cm and 36.1 cm2/V s, respectively. In addition, the mechanism concerning the influence of substrate temperature on the microstructure of TiN films is discussed in detail.

Photocatalytic growth of Ag nanocrystals on hydrothermally synthesized multiphasic TiO2/reduced graphene oxide (rGO) nanocomposites and their SERS performance

NASA Astrophysics Data System (ADS)

Guo, Tian-Long; Li, Ji-Guang; Sun, Xudong; Sakka, Yoshio

2017-11-01

TiO2/reduced graphene oxide (rGO) nanocomposites were prepared via a facile one-step hydrothermal method using TiCl3 as the TiO2 precursor. Cetyltrimethyl ammonium bromide (CTAB) was introduced as a stabilizer for GO in solution. The effects of GO content, Ti3+ concentration and urea additive on phase constituent and morphology of the TiO2 crystallites in the nanocomposites were systematically investigated. UV-vis absorption ability of the as-made composites was further tested and discussed. Ag nanocrystals (NCs) were photocatalytically grown on the surfaces of biphasic (anatase + brookite) and triphasic (anatase + brookite + rutile) TiO2/rGO nanocomposites to evaluate their surface-enhanced Raman scattering (SERS) performances. Morphology evolution of the Ag NCs in response to different photocatalytic ability of the TiO2/rGO nanocomposite was also investigated in detail. The nanocomposite with triphasic TiO2 of proper phase constituents was confirmed to favor the growth of Ag particles of two distinctly different sizes and to produce SERS substrates of substantially better performance.

2D simulations of orthogonal cutting of CFRP: Effect of tool angles on parameters of cut and chip morphology

NASA Astrophysics Data System (ADS)

Benhassine, Mehdi; Rivière-Lorphèvre, Edouard; Arrazola, Pedro-Jose; Gobin, Pierre; Dumas, David; Madhavan, Vinay; Aizpuru, Ohian; Ducobu, François

2018-05-01

Carbon-fiber reinforced composites (CFRP) are attractive materials for lightweight designs in applications needing good mechanical properties. Machining of such materials can be harder than metals due to their anisotropic behavior. In addition, the combination of the fibers and resin mechanical properties must also include the fiber orientation. In the case of orthogonal cutting, the tool inclination, rake angle or cutting angle usually influence the cutting process but such a detailed investigation is currently lacking in a 2D configuration. To address this issue, a model has been developed with Abaqus Explicit including Hashin damage. This model has been validated with experimental results from the literature. The effects of the tool parameters (rake angle, clearance angle) on the tool cutting forces, CFRP chip morphology and surface damage are herewith studied. It is shown that 90° orientation for the CFRP increases the surface damage. The rake angle has a minimal effect on the cutting forces but modifies the chip formation times. The feed forces are increased with increasing rake angle.

Bivariate mass-size relation as a function of morphology as determined by Galaxy Zoo 2 crowdsourced visual classifications

NASA Astrophysics Data System (ADS)

Beck, Melanie; Scarlata, Claudia; Fortson, Lucy; Willett, Kyle; Galloway, Melanie

2016-01-01

It is well known that the mass-size distribution evolves as a function of cosmic time and that this evolution is different between passive and star-forming galaxy populations. However, the devil is in the details and the precise evolution is still a matter of debate since this requires careful comparison between similar galaxy populations over cosmic time while simultaneously taking into account changes in image resolution, rest-frame wavelength, and surface brightness dimming in addition to properly selecting representative morphological samples.Here we present the first step in an ambitious undertaking to calculate the bivariate mass-size distribution as a function of time and morphology. We begin with a large sample (~3 x 105) of SDSS galaxies at z ~ 0.1. Morphologies for this sample have been determined by Galaxy Zoo crowdsourced visual classifications and we split the sample not only by disk- and bulge-dominated galaxies but also in finer morphology bins such as bulge strength. Bivariate distribution functions are the only way to properly account for biases and selection effects. In particular, we quantify the mass-size distribution with a version of the parametric Maximum Likelihood estimator which has been modified to account for measurement errors as well as upper limits on galaxy sizes.

Repeated Origin and Loss of Adhesive Toepads in Geckos

PubMed Central

Gamble, Tony; Greenbaum, Eli; Jackman, Todd R.; Russell, Anthony P.; Bauer, Aaron M.

2012-01-01

Geckos are well known for their extraordinary clinging abilities and many species easily scale vertical or even inverted surfaces. This ability is enabled by a complex digital adhesive mechanism (adhesive toepads) that employs van der Waals based adhesion, augmented by frictional forces. Numerous morphological traits and behaviors have evolved to facilitate deployment of the adhesive mechanism, maximize adhesive force and enable release from the substrate. The complex digital morphologies that result allow geckos to interact with their environment in a novel fashion quite differently from most other lizards. Details of toepad morphology suggest multiple gains and losses of the adhesive mechanism, but lack of a comprehensive phylogeny has hindered efforts to determine how frequently adhesive toepads have been gained and lost. Here we present a multigene phylogeny of geckos, including 107 of 118 recognized genera, and determine that adhesive toepads have been gained and lost multiple times, and remarkably, with approximately equal frequency. The most likely hypothesis suggests that adhesive toepads evolved 11 times and were lost nine times. The overall external morphology of the toepad is strikingly similar in many lineages in which it is independently derived, but lineage-specific differences are evident, particularly regarding internal anatomy, with unique morphological patterns defining each independent derivation. PMID:22761794

Discrepancy between species borders at morphological and molecular levels in the genus Cochliopodium (Amoebozoa, Himatismenida), with the description of Cochliopodium plurinucleolum n. sp.

PubMed

Geisen, Stefan; Kudryavtsev, Alexander; Bonkowski, Michael; Smirnov, Alexey

2014-05-01

Amoebae of the genus Cochliopodium are characterized by a tectum that is a layer of scales covering the dorsal surface of the cell. A combination of scale structure, morphological features and, nowadays, molecular information allows species discrimination. Here we describe a soil species Cochliopodium plurinucleolum n. sp. that besides strong genetic divergence from all currently described species of Cochliopodium differs morphologically by the presence of several peripheral nucleoli in the nucleus. Further, we unambiguously show that the Golgi attachment associated with a dictyosome in Cochliopodium is a cytoplasmic microtubule organizing center (MTOC). Last, we provide detailed morphological and molecular information on the sister clade of C. plurinucleolum, containing C. minus, C. minutoidum, C. pentatrifurcatum and C. megatetrastylus. These species share nearly identical sequences of both, small subunit ribosomal RNA and partial Cox1 genes, and nearly identical structure of the scales. Scales of C. pentatrifurcatum differ, however, strongly from scales of the others while sequences of C. pentatrifurcatum and C. minus are nearly identical. These discrepancies urge for future sampling efforts to disentangle species characteristics within Cochliopdium and to investigate morphological and molecular patterns that allow reliable species differentiation. Copyright © 2014 Elsevier GmbH. All rights reserved.

Microstructures and growth mechanisms of GaN films epitaxially grown on AlN/Si hetero-structures by pulsed laser deposition at different temperatures.

PubMed

Wang, Wenliang; Yang, Weijia; Lin, Yunhao; Zhou, Shizhong; Li, Guoqiang

2015-11-13

2 inch-diameter GaN films with homogeneous thickness distribution have been grown on AlN/Si(111) hetero-structures by pulsed laser deposition (PLD) with laser rastering technique. The surface morphology, crystalline quality, and interfacial property of as-grown GaN films are characterized in detail. By optimizing the laser rastering program, the ~300 nm-thick GaN films grown at 750 °C show a root-mean-square (RMS) thickness inhomogeneity of 3.0%, very smooth surface with a RMS surface roughness of 3.0 nm, full-width at half-maximums (FWHMs) for GaN(0002) and GaN(102) X-ray rocking curves of 0.7° and 0.8°, respectively, and sharp and abrupt AlN/GaN hetero-interfaces. With the increase in the growth temperature from 550 to 850 °C, the surface morphology, crystalline quality, and interfacial property of as-grown ~300 nm-thick GaN films are gradually improved at first and then decreased. Based on the characterizations, the corresponding growth mechanisms of GaN films grown on AlN/Si hetero-structures by PLD with various growth temperatures are hence proposed. This work would be beneficial to understanding the further insight of the GaN films grown on Si(111) substrates by PLD for the application of GaN-based devices.

Generalized model for laser-induced surface structure in metallic glass

NASA Astrophysics Data System (ADS)

Lin-Mao, Ye; Zhen-Wei, Wu; Kai-Xin, Liu; Xiu-Zhang, Tang; Xiang-Ming, Xiong

2016-06-01

The details of the special three-dimensional micro-nano scale ripples with a period of hundreds of microns on the surfaces of a Zr-based and a La-based metallic glass irradiated separately by single laser pulse are investigated. We use the small-amplitude capillary wave theory to unveil the ripple formation mechanism through considering each of the molten metallic glasses as an incompressible viscous fluid. A generalized model is presented to describe the special morphology, which fits the experimental result well. It is also revealed that the viscosity brings about the biggest effect on the monotone decreasing nature of the amplitude and the wavelength of the surface ripples. The greater the viscosity is, the shorter the amplitude and the wavelength are. Project supported by the National Natural Science Foundation of China (Grant Nos. 10572002, 10732010, and 11332002).

An Assessment of Stream Confluence Flow Dynamics using Large Scale Particle Image Velocimetry Captured from Unmanned Aerial Systems

NASA Astrophysics Data System (ADS)

Lewis, Q. W.; Rhoads, B. L.

2017-12-01

The merging of rivers at confluences results in complex three-dimensional flow patterns that influence sediment transport, bed morphology, downstream mixing, and physical habitat conditions. The capacity to characterize comprehensively flow at confluences using traditional sensors, such as acoustic Doppler velocimeters and profiles, is limited by the restricted spatial resolution of these sensors and difficulties in measuring velocities simultaneously at many locations within a confluence. This study assesses two-dimensional surficial patterns of flow structure at a small stream confluence in Illinois, USA, using large scale particle image velocimetry (LSPIV) derived from videos captured by unmanned aerial systems (UAS). The method captures surface velocity patterns at high spatial and temporal resolution over multiple scales, ranging from the entire confluence to details of flow within the confluence mixing interface. Flow patterns at high momentum ratio are compared to flow patterns when the two incoming flows have nearly equal momentum flux. Mean surface flow patterns during the two types of events provide details on mean patterns of surface flow in different hydrodynamic regions of the confluence and on changes in these patterns with changing momentum flux ratio. LSPIV data derived from the highest resolution imagery also reveal general characteristics of large-scale vortices that form along the shear layer between the flows during the high-momentum ratio event. The results indicate that the use of LSPIV and UAS is well-suited for capturing in detail mean surface patterns of flow at small confluences, but that characterization of evolving turbulent structures is limited by scale considerations related to structure size, image resolution, and camera instability. Complementary methods, including camera platforms mounted at fixed positions close to the water surface, provide opportunities to accurately characterize evolving turbulent flow structures in confluences.

Comparative morphology of the scales of roundscale spearfish Tetrapturus georgii and white marlin Kajikia albida.

PubMed

Loose, E L; Hilton, E J; Graves, J E

2017-04-01

The comparative morphology of the scales of roundscale spearfish Tetrapturus georgii and white marlin Kajikia albida was investigated. In addition, variation in scale morphology across different body regions within each species was analysed. Although considerable morphological variation was observed among scales from different body regions in both species, scales of K. albida generally have pointed anterior ends, fewer posterior points and are more heavily imbricated than those of T. georgii, which are frequently rounded anteriorly, often have many posterior points and are separated farther within the skin. In all sampled body regions and individuals, scales of T. georgii are significantly broader and have a lower length-to-width aspect ratio than those of K. albida. Superficial to the scales are denticular plates, which are ossified formations occurring on the surface layer of the epidermis; these were observed and described for T. georgii, K. albida and blue marlin Makaira nigricans. Detailed scale descriptions allow for a more accurate characterization of the variation within and differences between these two species and could potentially be a valuable tool for investigating istiophorid systematics. © 2017 The Fisheries Society of the British Isles.

Effects of high energy radiation on the mechanical properties of epoxy/graphite fiber composites

NASA Technical Reports Server (NTRS)

Fornes, R. E.; Memory, J. D.

1981-01-01

Studies on the effects of high energy radiation on graphite fiber reinforced composites are summarized. Studies of T300/5208 and C6000/PMR15 composites, T300 fibers and the resin system MY720/DDS (tetraglycidyl-4,4'-diaminodiphenyl methane cured with diaminodiphenyl sulfone) are included. Radiation dose levels up to 8000 Mrads were obtained with no deleterious effects on the breaking stress or modulus. The effects on the structure and morphology were investigated using mechanical tests, electron spin resonance, X-ray diffraction, and electron spectroscopy for chemical analysis (ESCA or X-ray photoelectron spectroscopy). Details of the experiments and results are given. Studies of the fracture surfaces of irradiated samples were studied with scanning electron microscopy; current results indicate no differences in the morphology of irradiated and control samples.

The Characteristics of Fatigue Damage in the Fuselage Riveted Lap Splice Joint

NASA Technical Reports Server (NTRS)

Piascik, Robert S.; Willard, Scott A.

1997-01-01

An extensive data base has been developed to form the physical basis for new analytical methodology to predict the onset of widespread fatigue damage in the fuselage lap splice joint. The results of detailed destructive examinations have been cataloged to describe the physical nature of MSD in the lap splice joint. ne catalog includes a detailed description, e.g., crack initiation, growth rates, size, location, and fracture morphology, of fatigue damage in the fuselage lap splice joint structure. Detailed examinations were conducted on a lap splice joint panel removed from a full scale fuselage test article after completing a 60,000 cycle pressure test. The panel contained a four bay region that exhibited visible outer skin cracks and regions of crack link-up along the upper rivet row. Destructive examinations revealed undetected fatigue damage in the outer skin, inner skin, and tear strap regions. Outer skin fatigue cracks were found to initiate by fretting damage along the faying surface. The cracks grew along the faying surface to a length equivalent to two to three skin thicknesses before penetrating the outboard surface of the outer skin. Analysis of fracture surface marker bands produced during full scale testing revealed that all upper rivet row fatigue cracks contained in a dim bay region grow at similar rates; this important result suggests that fracture mechanics based methods can be used to predict the growth of outer skin fatigue cracks in lap splice structure. Results are presented showing the affects of MSD and out-of-plane pressure loads on outer skin crack link-up.

Revision and Microtomography of the Pheidole knowlesi Group, an Endemic Ant Radiation in Fiji (Hymenoptera, Formicidae, Myrmicinae)Myrmicinae).

PubMed

Fischer, Georg; Sarnat, Eli M; Economo, Evan P

2016-01-01

The Fijian islands, a remote archipelago in the southwestern Pacific, are home to a number of spectacular endemic radiations of plants and animals. Unlike most Pacific archipelagos, these evolutionary radiations extend to social insects, including ants. One of the most dramatic examples of ant radiation in Fiji has occurred in the hyperdiverse genus Pheidole. Most of the 17 native Fijian Pheidole belong to one of two species groups that descended from a single colonization, yet have evolved dramatically contrasting morphologies: the spinescent P. roosevelti species group, and the more morphologically conservative P. knowlesi species group. Here we revise the knowlesi group, in light of recent phylogenetic results, and enhanced with modern methods of X-ray microtomography. We recognize six species belonging to this group, including two of which we describe as new: Pheidole caldwelli Mann, Pheidole kava sp. n., Pheidole knowlesi Mann, P. ululevu sp. n., P. vatu Mann, and P. wilsoni Mann. Detailed measurements and descriptions, identification keys, and high-resolution images for queens, major and minor workers are provided. In addition, we include highly detailed 3D surface reconstructions for all available castes.

The Mars Orbital Catalog of Hydrated Alteration Signatures (MOCHAS) - Initial release

NASA Astrophysics Data System (ADS)

Carter, John; OMEGA and CRISM Teams

2016-10-01

Aqueous minerals have been identified from orbit at a number of localities, and their analysis allowed refining the water story of Early Mars. They are also a main science driver when selecting current and upcoming landing sites for roving missions.Available catalogs of mineral detections exhibit a number of drawbacks such as a limited sample size (a thousand sites at most), inhomogeneous sampling of the surface and of the investigation methods, and the lack of contextual information (e.g. spatial extent, morphological context). The MOCHAS project strives to address such limitations by providing a global, detailed survey of aqueous minerals on Mars based on 10 years of data from the OMEGA and CRISM imaging spectrometers. Contextual data is provided, including deposit sizes, morphology and detailed composition when available. Sampling biases are also addressed.It will be openly distributed in GIS-ready format and will be participative. For example, it will be possible for researchers to submit requests for specific mapping of regions of interest, or add/refine mineral detections.An initial release is scheduled in Fall 2016 and will feature a two orders of magnitude increase in sample size compared to previous studies.

Morphological studies of the vestibular nerve

NASA Technical Reports Server (NTRS)

Bergstroem, B.

1973-01-01

The anatomy of the intratemporal part of the vestibular nerve in man, and the possible age related degenerative changes in the nerve were studied. The form and structure of the vestibular ganglion was studied with the light microscope. A numerical analysis of the vestibular nerve, and caliber spectra of the myelinated fibers in the vestibular nerve branches were studied in individuals of varying ages. It was found that the peripheral endings of the vestibular nerve form a complicated pattern inside the vestibular sensory epithelia. A detailed description of the sensory cells and their surface organelles is included.

Television observations of Mercury by Mariner 10

NASA Technical Reports Server (NTRS)

Murray, B. C.; Belton, M. J. S.; Danielson, E. G.; Davies, M. E.; Gault, D. E.; Hapke, B.; Oleary, B.; Strom, R. G.; Suomi, V.; Trask, N.

1977-01-01

The morphology and optical properties of the surface of Mercury resemble those of the Moon in remarkable detail, recording a very similar sequence of events; chemical and mineralogical similarity of the outer layers is implied. Mercury is probably a differentiated planet with an iron-rich core. Differentiation is inferred to have occurred very early. No evidence of atmospheric modification of any landform is found. Large-scale scarps and ridges unlike lunar or Martian features may reflect a unique period of planetary compression near the end of heavy bombardment, perhaps related to contraction of the core.

Television observations of Mercury by Mariner 10

NASA Technical Reports Server (NTRS)

Murray, B. C.; Belton, M. J. S.; Danielson, G. E.; Davies, M. E.; Gault, D. E.; Hapke, B.; Oleary, B.; Strom, R. G.; Suomi, V.; Trask, N.

1974-01-01

The morphology and optical properties of the surface of Mercury resemble that of the moon in remarkable detail, recording a very similar sequence of events; chemical and mineralogical similarity of the outer layers is implied. Mercury is probably a differentiated planet with an iron-rich core. Differentiation is inferred to have occurred very early. No evidence of atmospheric modification of any landform is found. Large-scale scarps and ridges unlike lunar or Martian features may reflect a unique period of planetary compression near the end of heavy bombardment, perhaps related to contraction of the core.

Hippocampus and Amygdala Morphology in Attention-Deficit/Hyperactivity Disorder

PubMed Central

Plessen, Kerstin J.; Bansal, Ravi; Zhu, Hongtu; Whiteman, Ronald; Amat, Jose; Quackenbush, Georgette A.; Martin, Laura; Durkin, Kathleen; Blair, Clancy; Royal, Jason; Hugdahl, Kenneth; Peterson, Bradley S.

2008-01-01

Context Limbic structures are implicated in the genesis of attention-deficit/hyperactivity disorder (ADHD) by the presence of mood and cognitive disturbances in affected individuals and by elevated rates of mood disorders in family members of probands with ADHD. Objective To study the morphology of the hippocampus and amygdala in children with ADHD. Design A cross-sectional case-control study of the hippocampus and amygdala using anatomical magnetic resonance imaging. Settings University research institute. Patients One hundred fourteen individuals aged 6 to 18 years, 51 with combined-type ADHD and 63 healthy controls. Main Outcome Measures Volumes and measures of surface morphology for the hippocampus and amygdala. Results The hippocampus was larger bilaterally in the ADHD group than in the control group (t=3.35; P<.002). Detailed surface analyses of the hippocampus further localized these differences to an enlarged head of the hippocampus in the ADHD group. Although conventional measures did not detect significant differences in amygdalar volumes, surface analyses indicated the presence of reduced size bilaterally over the area of the basolateral complex. Correlations with prefrontal measures suggested abnormal connectivity between the amygdala and prefrontal cortex in the ADHD group. Enlarged subregions of the hippocampus tended to accompany fewer symptoms. Conclusions The enlarged hippocampus in children and adolescents with ADHD may represent a compensatory response to the presence of disturbances in the perception of time, temporal processing (eg, delay aversion), and stimulus seeking associated with ADHD. Disrupted connections between the amygdala and orbitofrontal cortex may contribute to behavioral disinhibition. Our findings suggest involvement of the limbic system in the pathophysiology of ADHD. PMID:16818869

Updating the planetary time scale: focus on Mars

USGS Publications Warehouse

Tanaka, Kenneth L.; Quantin-Nataf, Cathy

2013-01-01

Formal stratigraphic systems have been developed for the surface materials of the Moon, Mars, Mercury, and the Galilean satellite Ganymede. These systems are based on geologic mapping, which establishes relative ages of surfaces delineated by superposition, morphology, impact crater densities, and other relations and features. Referent units selected from the mapping determine time-stratigraphic bases and/or representative materials characteristic of events and periods for definition of chronologic units. Absolute ages of these units in some cases can be estimated using crater size-frequency data. For the Moon, the chronologic units and cratering record are calibrated by radiometric ages measured from samples collected from the lunar surface. Model ages for other cratered planetary surfaces are constructed primarily by estimating cratering rates relative to that of the Moon. Other cratered bodies with estimated surface ages include Venus and the Galilean satellites of Jupiter. New global geologic mapping and crater dating studies of Mars are resulting in more accurate and detailed reconstructions of its geologic history.

Polyethylene Oxide Films Polymerized by Radio Frequency Plasma-Enhanced Chemical Vapour Phase Deposition and Its Adsorption Behaviour of Platelet-Rich Plasma

NASA Astrophysics Data System (ADS)

Hu, Wen-Juan; Xie, Fen-Yan; Chen, Qiang; Weng, Jing

2008-10-01

We present polyethylene oxide (PEO) functional films polymerized by rf plasma-enhanced vapour chemical deposition (rf-PECVD) on p-Si (100) surface with precursor ethylene glycol dimethyl ether (EGDME) and diluted Ar in pulsed plasma mode. The influences of discharge parameters on the film properties and compounds are investigated. The film structure is analysed by Fourier transform infrared (FTIR) spectroscopy. The water contact angle measurement and atomic force microscope (AFM) are employed to examine the surface polarity and to detect surface morphology, respectively. It is concluded that the smaller duty cycle in pulsed plasma mode contributes to the rich C-O-C (EO) group on the surfaces. As an application, the adsorption behaviour of platelet-rich plasma on plasma polymerization films performed in-vitro is explored. The shapes of attached cells are studied in detail by an optic invert microscope, which clarifies that high-density C-O-C groups on surfaces are responsible for non-fouling adsorption behaviour of the PEO films.

Gasification reactor engineering approach to understanding the formation of biochar properties

PubMed Central

2016-01-01

The correlation between thermochemical provenance and biochar functionality is poorly understood. To this end, operational reactor temperatures (spanning the reduction zone), pressure and product gas composition measurements were obtained from a downdraft gasifier and compared against elemental composition, surface morphology and polyaromatic hydrocarbon content (PAH) of the char produced. Pine feedstock moisture with values of 7% and 17% was the experimental variable. Moderately high steady-state temperatures were observed inside the reactor, with a ca 50°C difference in how the gasifier operated between the two feedstock types. Both chars exhibited surface properties comparable to activated carbon, but the relatively small differences in temperature caused significant variations in biochar surface area and morphology: micropore area 584 against 360 m2 g−1, and micropore volume 0.287 against 0.172 cm3 g−1. Differences in char extractable PAH content were also observed, with higher concentrations (187 µg g−1 ± 18 compared with 89 ± 19 µg g−1 Σ16EPA PAH) when the gasifier was operated with higher moisture content feedstock. It is recommended that greater detail on operational conditions during biochar production should be incorporated to future biochar characterization research as a consequence of these results. PMID:27616911

Formation of aggregated nanoparticle spheres through femtosecond laser surface processing

NASA Astrophysics Data System (ADS)

Tsubaki, Alfred T.; Koten, Mark A.; Lucis, Michael J.; Zuhlke, Craig; Ianno, Natale; Shield, Jeffrey E.; Alexander, Dennis R.

2017-10-01

A detailed structural and chemical analysis of a class of self-organized surface structures, termed aggregated nanoparticle spheres (AN-spheres), created using femtosecond laser surface processing (FLSP) on silicon, silicon carbide, and aluminum is reported in this paper. AN-spheres are spherical microstructures that are 20-100 μm in diameter and are composed entirely of nanoparticles produced during femtosecond laser ablation of material. AN-spheres have an onion-like layered morphology resulting from the build-up of nanoparticle layers over multiple passes of the laser beam. The material properties and chemical composition of the AN-spheres are presented in this paper based on scanning electron microscopy (SEM), focused ion beam (FIB) milling, transmission electron microscopy (TEM), and energy dispersive x-ray spectroscopy (EDX) analysis. There is a distinct difference in the density of nanoparticles between concentric rings of the onion-like morphology of the AN-sphere. Layers of high-density form when the laser sinters nanoparticles together and low-density layers form when nanoparticles redeposit while the laser ablates areas surrounding the AN-sphere. The dynamic nature of femtosecond laser ablation creates a variety of nanoparticles that make-up the AN-spheres including Si/C core-shell, nanoparticles that directly fragmented from the base material, nanoparticles with carbon shells that retarded oxidation, and amorphous, fully oxidized nanoparticles.

Fractional Diffusion, Low Exponent Lévy Stable Laws, and 'Slow Motion' Denoising of Helium Ion Microscope Nanoscale Imagery.

PubMed

Carasso, Alfred S; Vladár, András E

2012-01-01

Helium ion microscopes (HIM) are capable of acquiring images with better than 1 nm resolution, and HIM images are particularly rich in morphological surface details. However, such images are generally quite noisy. A major challenge is to denoise these images while preserving delicate surface information. This paper presents a powerful slow motion denoising technique, based on solving linear fractional diffusion equations forward in time. The method is easily implemented computationally, using fast Fourier transform (FFT) algorithms. When applied to actual HIM images, the method is found to reproduce the essential surface morphology of the sample with high fidelity. In contrast, such highly sophisticated methodologies as Curvelet Transform denoising, and Total Variation denoising using split Bregman iterations, are found to eliminate vital fine scale information, along with the noise. Image Lipschitz exponents are a useful image metrology tool for quantifying the fine structure content in an image. In this paper, this tool is applied to rank order the above three distinct denoising approaches, in terms of their texture preserving properties. In several denoising experiments on actual HIM images, it was found that fractional diffusion smoothing performed noticeably better than split Bregman TV, which in turn, performed slightly better than Curvelet denoising.

Thermally Switchable Thin Films of an ABC Triblock Copolymer of Poly(n-butyl methacrylate)-poly(methyl methacrylate)-poly(2-fluoroethyl methacrylate)

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

Zhang, Shanju; Liu, Zhan; Bucknall, David G.

2011-01-01

The thermo-responsive behavior of polymer films consisting of novel linear triblock copolymers of poly(n-butyl methacrylate)-poly(methyl methacrylate)-poly(2-fluoroethyl methacrylate) (PnBuMA-PMMA-P2FEMA) are reported using differential scanning calorimetry (DSC), atomic forcing microscopy (AFM), X-ray photoelectron spectroscopy (XPS) and contacting angle (CA) measurements. The surface morphology, wettability and chemical structure of thin films of these triblock copolymers on silicon wafers as a function of temperature have been investigated. It has been shown that the wettability of the films is thermally switchable. Detailed structural analysis shows that thermo-responsive surface composition changes are produced. The underlying mechanism of the thermoresponsive behavior is discussed.

Colors of active regions on comet 67P

NASA Astrophysics Data System (ADS)

Oklay, N.; Vincent, J.-B.; Sierks, H.; Besse, S.; Fornasier, S.; Barucci, M. A.; Lara, L.; Scholten, F.; Preusker, F.; Lazzarin, M.; Pajola, M.; La Forgia, F.

2015-10-01

The OSIRIS (Optical, Spectroscopic, and Infrared Remote Imaging System) scientific imager (Keller et al. 2007) is successfully delivering images of comet 67P/Churyumov-Gerasimenko from its both wide angle camera (WAC) and narrow angle camera (NAC) since ESA's spacecraft Rosetta's arrival to the comet. Both cameras are equipped with filters covering the wavelength range of about 200 nm to 1000 nm. The comet nucleus is mapped with different combination of the filters in resolutions up to 15 cm/px. Besides the determination of the surface morphology in great details (Thomas et al. 2015), such high resolution images provided us a mean to unambiguously link some activity in the coma to a series of pits on the nucleus surface (Vincent et al. 2015).

3D surface reconstruction and visualization of the Drosophila wing imaginal disc at cellular resolution

NASA Astrophysics Data System (ADS)

Bai, Linge; Widmann, Thomas; Jülicher, Frank; Dahmann, Christian; Breen, David

2013-01-01

Quantifying and visualizing the shape of developing biological tissues provide information about the morphogenetic processes in multicellular organisms. The size and shape of biological tissues depend on the number, size, shape, and arrangement of the constituting cells. To better understand the mechanisms that guide tissues into their final shape, it is important to investigate the cellular arrangement within tissues. Here we present a data processing pipeline to generate 3D volumetric surface models of epithelial tissues, as well as geometric descriptions of the tissues' apical cell cross-sections. The data processing pipeline includes image acquisition, editing, processing and analysis, 2D cell mesh generation, 3D contourbased surface reconstruction, cell mesh projection, followed by geometric calculations and color-based visualization of morphological parameters. In their first utilization we have applied these procedures to construct a 3D volumetric surface model at cellular resolution of the wing imaginal disc of Drosophila melanogaster. The ultimate goal of the reported effort is to produce tools for the creation of detailed 3D geometric models of the individual cells in epithelial tissues. To date, 3D volumetric surface models of the whole wing imaginal disc have been created, and the apicolateral cell boundaries have been identified, allowing for the calculation and visualization of cell parameters, e.g. apical cross-sectional area of cells. The calculation and visualization of morphological parameters show position-dependent patterns of cell shape in the wing imaginal disc. Our procedures should offer a general data processing pipeline for the construction of 3D volumetric surface models of a wide variety of epithelial tissues.

The properties and behavior of α-pinene secondary organic aerosol particles exposed to ammonia under dry conditions

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

Bell, David M.; Imre, Dan; T. Martin, Scot

Chemical transformations and aging of secondary organic aerosol (SOA) particles can alter their physical and chemical properties, including particle morphology. Ammonia, one of the common atmospheric reactive constituents, can react with SOA particles, changing their properties and behavior. At low relative humidity NH3 uptake by α-pinene SOA particles appears to be limited to the particle surface, which suggests that the reacted particles might not be homogeneous and have complex morphology. Here, we present a study aimed at detailed characterization of the effect of ammonia on the composition, density, morphology, shape, and evaporation kinetics of α-pinene SOA particles. We find thatmore » a small amount of NH3 diffuses and reacts throughout the particles bulk, while most of the ammoniated products result from the reaction of NH3 with carboxylic acids on the particle surface, leading to a slight increase in particle size. We show that the reaction products form a solid semi-volatile coating that is a few nanometers thick. This solid coating prevents coagulating particles from coalescing for over two days. However, when the gas phase is diluted this semi-volatile coating evaporates in minutes, which is ensued by rapid coalescence. The ammoniated products in the particle bulk affect particles evaporation kinetics, more so for the smaller particles that contain higher fraction of ammoniated products.« less

Quantifying temporal bone morphology of great apes and humans: an approach using geometric morphometrics.

PubMed

Lockwood, Charles A; Lynch, John M; Kimbel, William H

2002-12-01

The hominid temporal bone offers a complex array of morphology that is linked to several different functional systems. Its frequent preservation in the fossil record gives the temporal bone added significance in the study of human evolution, but its morphology has proven difficult to quantify. In this study we use techniques of 3D geometric morphometrics to quantify differences among humans and great apes and discuss the results in a phylogenetic context. Twenty-three landmarks on the ectocranial surface of the temporal bone provide a high level of anatomical detail. Generalized Procrustes analysis (GPA) is used to register (adjust for position, orientation and scale) landmark data from 405 adults representing Homo, Pan, Gorilla and Pongo. Principal components analysis of residuals from the GPA shows that the major source of variation is between humans and apes. Human characteristics such as a coronally orientated petrous axis, a deep mandibular fossa, a projecting mastoid process, and reduced lateral extension of the tympanic element strongly impact the analysis. In phenetic cluster analyses, gorillas and orangutans group together with respect to chimpanzees, and all apes group together with respect to humans. Thus, the analysis contradicts depictions of African apes as a single morphotype. Gorillas and orangutans lack the extensive preglenoid surface of chimpanzees, and their mastoid processes are less medially inflected. These and other characters shared by gorillas and orangutans are probably primitive for the African hominid clade.

Surface morphology and grain analysis of successively industrially grown amorphous hydrogenated carbon films (a-C:H) on silicon

NASA Astrophysics Data System (ADS)

Catena, Alberto; McJunkin, Thomas; Agnello, Simonpietro; Gelardi, Franco M.; Wehner, Stefan; Fischer, Christian B.

2015-08-01

Silicon (1 0 0) has been gradually covered by amorphous hydrogenated carbon (a-C:H) films via an industrial process. Two types of these diamond-like carbon (DLC) coatings, one more flexible (f-DLC) and one more robust (r-DLC), have been investigated. Both types have been grown by a radio frequency plasma-enhanced chemical vapor deposition (RF-PECVD) technique with acetylene plasma. Surface morphologies have been studied in detail by atomic force microscopy (AFM) and Raman spectroscopy has been used to investigate the DLC structure. Both types appeared to have very similar morphology and sp2 carbon arrangement. The average height and area for single grains have been analyzed for all depositions. A random distribution of grain heights was found for both types. The individual grain structures between the f- and r-type revealed differences: the shape for the f-DLC grains is steeper than for the r-DLC grains. By correlating the average grain heights to the average grain areas for all depositions a limited region is identified, suggesting a certain regularity during the DLC deposition mechanisms that confines both values. A growth of the sp2 carbon entities for high r-DLC depositions is revealed and connected to a structural rearrangement of carbon atom hybridizations and hydrogen content in the DLC structure.

Effects of the New Madrid earthquake series in the Mississippi Alluvial Valley. Final report

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

Saucier, R.T.

1977-02-01

Geological effects of the New Madrid earthquake series of 1811-12 in the upper portion of the Lower Mississippi Valley include land subsidence, uplift or doming, landslides, bank caving, fissuring, and sand blow phenomena. Features resulting from the liquefaction of sand are widespread in the alluvial valley and offer the greatest potential for definitively assessing the effects of major earthquakes on thick alluvial deposits and predicting the recurrence interval of infrequent major earthquakes in the region. However, liquefaction phenomena have not been the subject of detailed geological investigations applying knowledge of alluvial morphology and earth sciences methodology. Comparative aerial photo interpretationmore » has been used to classify liquefaction phenomena according to morphology, distribution, and relationship to major depositional environments. Surface morphology and spatial distribution of sand blows and fissures indicate basic control by drainage lines, water table position, and thickness of fine-grained topstratum deposits, Research efforts have been aimed at locating field test sites where the subsurface expression of the liquefaction phenomena can be investigated through trenching and land planing. Subsurface expression is presumed to be more permanent than surface expression and may permit the recognition of such features in older formations. Evidence of fissures and related phenomena is being sought in older Quaternary deposits to permit estimates of the frequency of past major earthquakes.« less

Increased Insular Cortical Thickness Associated With Symptom Severity in Male Youths With Internet Gaming Disorder: A Surface-Based Morphometric Study

PubMed Central

Wang, Shuai; Liu, Jing; Tian, Lin; Chen, Limin; Wang, Jun; Tang, Qunfeng; Zhang, Fuquan; Zhou, Zhenhe

2018-01-01

With the rising increase in Internet-usage, Internet gaming disorder (IGD) has gained massive attention worldwide. However, detailed cerebral morphological changes remain unclear in youths with IGD. In the current study, our aim was to investigate cortical morphology and further explore the relationship between the cortical morphology and symptom severity in male youths with IGD. Forty-eight male youths with IGD and 32 age- and education-matched normal controls received magnetic resonance imaging scans. We employed a recently proposed surface-based morphometric approach for the measurement of cortical thickness (CT). We found that youths with IGD showed increased CT in the bilateral insulae and the right inferior temporal gyrus. Moreover, significantly decreased CT were found in several brain areas in youths with IGD, including the bilateral banks of the superior temporal sulci, the right inferior parietal cortex, the right precuneus, the right precentral gyrus, and the left middle temporal gyrus. Additionally, youths with IGD demonstrated a significantly positive correlation between the left insular CT and symptom severity. Our data provide evidence for the finding of abnormal CT in distributed cerebral areas and support the notion that altered structural abnormalities observed in substance addiction are also manifested in IGD. Such information extends current knowledge about IGD-related brain reorganization and could help future efforts in identifying the role of insula in the disorder. PMID:29666588

Techniques for Revealing 3d Hidden Archeological Features: Morphological Residual Models as Virtual-Polynomial Texture Maps

NASA Astrophysics Data System (ADS)

Pires, H.; Martínez Rubio, J.; Elorza Arana, A.

2015-02-01

The recent developments in 3D scanning technologies are not been accompanied by visualization interfaces. We are still using the same types of visual codes as when maps and drawings were made by hand. The available information in 3D scanning data sets is not being fully exploited by current visualization techniques. In this paper we present recent developments regarding the use of 3D scanning data sets for revealing invisible information from archaeological sites. These sites are affected by a common problem, decay processes, such as erosion, that never ceases its action and endangers the persistence of last vestiges of some peoples and cultures. Rock art engravings, or epigraphical inscriptions, are among the most affected by these processes because they are, due to their one nature, carved at the surface of rocks often exposed to climatic agents. The study and interpretation of these motifs and texts is strongly conditioned by the degree of conservation of the imprints left by our ancestors. Every single detail in the remaining carvings can make a huge difference in the conclusions taken by specialists. We have selected two case-studies severely affected by erosion to present the results of the on-going work dedicated to explore in new ways the information contained in 3D scanning data sets. A new method for depicting subtle morphological features in the surface of objects or sites has been developed. It allows to contrast human patterns still present at the surface but invisible to naked eye or by any other archaeological inspection technique. It was called Morphological Residual Model (MRM) because of its ability to contrast the shallowest morphological details, to which we refer as residuals, contained in the wider forms of the backdrop. Afterwards, we have simulated the process of building Polynomial Texture Maps - a widespread technique that as been contributing to archaeological studies for some years - in a 3D virtual environment using the results of MRM calculations. By this, we wish to benefit from the rendering capabilities of RTI-viewer and from its intuitive graphic interface. At the same time, virtual PTM is a way of applying this to areas barred to conventional PTM, like in the case presented of an entire roman city occupying a plateau of several sq. km. The results of this research project are presented and discussed using the two case-studies aforementioned, a Latin inscription from a Roman sanctuary in the north of Portugal and a engraved panel with zoomorphic motifs from a rock art site in the north border of Portugal.

Multiscale Investigations of the Early Stage Oxidation on Cu Surfaces

NASA Astrophysics Data System (ADS)

Zhu, Qing; Xiao, Penghao; Lian, Xin; Yang, Shen-Che; Henkelman, Grame; Saidi, Wissam; Yang, Judith; University of Pittsburgh Team; University of Texas at Austin Team

Previous in situ TEM experiments have shown that the oxidation of the three low index Cu surfaces (100), (110) and (111) exhibit different oxide nucleation rates, and the resulting oxides have 3-dimensional (3D) island shapes or 2D rafts under different conditions. In order to better understand these results, we have investigated the early stages of Cu oxidation using a multiscale computational approach that employs density functional theory (DFT), reactive force field (ReaxFF), and kinetic Mote Carlo (KMC). With DFT calculation, we have compared O2 dissociation barriers on Cu (100), (110) and (111) surfaces at high oxygen coverage to evaluate the kinetic barrier of sublayer oxidization. We found that O2 dissociation barriers on Cu(111) surface are all lower than those on (110) and (100) surfaces. This trend agrees with experimental observations that (111) surface is easier to oxidize. These DFT calculated energy barriers are then incorporated into KMC simulations. The large scale ReaxFF molecular dynamics and KMC simulations detail the oxidation dynamics of the different Cu surfaces, and show the formation of various oxide morphologies that are consistent with experimental observations.

Parameterization experiments performed via synthetic mass movements prototypes generated by 3D slope stability simulator

NASA Astrophysics Data System (ADS)

Colangelo, Antonio C.

2010-05-01

The central purpose of this work is to perform a reverse procedure in the mass movement conventional parameterization approach. The idea is to generate a number of synthetic mass movements by means of the "slope stability simulator" (Colangelo, 2007), and compeer their morphological and physical properties with "real" conditions of effective mass movements. This device is an integrated part of "relief unity emulator" (rue), that permits generate synthetic mass movements in a synthetic slope environment. The "rue" was build upon fundamental geomorphological concepts. These devices operate with an integrated set of mechanical, geomorphic and hydrological models. The "slope stability simulator" device (sss) permits to perform a detailed slope stability analysis in a theoretical three dimensional space, by means of evaluation the spatial behavior of critical depths, gradients and saturation levels in the "potential rupture surfaces" inferred along a set of slope profiles, that compounds a synthetic slope unity. It's a meta-stable 4-dimensional object generated by means of "rue", that represents a sequence evolution of a generator profile applied here, was adapted the infinite slope model for slope. Any slope profiles were sliced by means of finite element solution like in Bishop method. For the synthetic slope systems generated, we assume that the potential rupture surface occurs at soil-regolith or soil-rock boundary in slope material. Sixteen variables were included in the "rue-sss" device that operates in an integrated manner. For each cell, the factor of safety was calculated considering the value of shear strength (cohesion and friction) of material, soil-regolith boundary depth, soil moisture level content, potential rupture surface gradient, slope surface gradient, top of subsurface flow gradient, apparent soil bulk density and vegetation surcharge. The slope soil was considered as cohesive material. The 16 variables incorporated in the models were analyzed for each cell in synthetic slope systems performed by relief unity emulator. The central methodological strategy is to locate the potential rupture surfaces (prs), main material discontinuities, like soil-regolith or regolith-rock transitions. Inner these "prs", we would to outline the effective potential rupture surfaces (eprs). This surface is a sub-set of the "prs" that presents safety factor less than unity (f<1), the sub-region in the "prs" equal or deeper than critical depths. When the effective potential rupture surface acquires significant extension with respect the thickness of critical depth and retaining walls, the "slope stability simulator" generates a synthetic mass movement. The overlay material will slide until that a new equilibrium be attained at residual shear strength. These devices generate graphic 3D cinematic sequences of experiments in synthetic slope systems and numerical results about physical and morphological data about scars and deposits. Thus, we have a detailed geotechnical, morphological, topographic and morphometric description of these mass movements prototypes, for deal with effective mass movements found in the real environments.

Confinement and surface effects on the physical properties of rhombohedral-shape hematite (α-Fe{sub 2}O{sub 3}) nanocrystals

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

Luna, Carlos, E-mail: carlos.lunacd@uanl.edu.mx; Cuan-Guerra, Aída D.; Barriga-Castro, Enrique D.

2016-08-15

Highlights: • Uniform rhombohedral hematite nanocrystals (RHNCs) have been obtained. • A detailed formation mechanism of these HNCS has been proposed. • Phonon confinement effects were revealed in the RHNCS vibrational bands. • Quantum confinement effects on the optical and electronic properties were found. - Abstract: Morphological, microstructural and vibrational properties of hematite (α-Fe{sub 2}O{sub 3}) nanocrystals with a rhombohedral shape and rounded edges, obtained by forced hydrolysis of iron(III) solutions under a fast nucleation, have been investigated in detail as a function of aging time. These studies allowed us to propose a detailed formation mechanism and revealed that thesemore » nanocrystals are composed of four {104} side facets, two {110} faces at the edges of the long diagonal of the nanocrystals and two {−441} facets as the top and bottom faces. Also, the presence of nanoscopic pores and fissures was evidenced. The vibrational bands of such nanocrystals were shifted to lower frequencies in comparison with bulk hematite ones as the nanocrystal size was reduced due to phonon confinement effects. Also, the indirect and direct transition band gaps displayed interesting dependences on the aging time arising from quantum confinement and surface effects.« less

Polythiophene thin films by surface-initiated polymerization: Mechanistic and structural studies

DOE PAGES

Youm, Sang Gil; Hwang, Euiyong; Chavez, Carlos A.; ...

2016-06-15

The ability to control nanoscale morphology and molecular organization in organic semiconducting polymer thin films is an important prerequisite for enhancing the efficiency of organic thin-film devices including organic light-emitting and photovoltaic devices. The current “top-down” paradigm for making such devices is based on utilizing solution-based processing (e.g., spin-casting) of soluble semiconducting polymers. This approach typically provides only modest control over nanoscale molecular organization and polymer chain alignment. A promising alternative to using solutions of presynthesized semiconducting polymers pursues instead a “bottom-up” approach to prepare surface-grafted semiconducting polymer thin films by surface-initiated polymerization of small-molecule monomers. Herein, we describe themore » development of an efficient method to prepare polythiophene thin films utilizing surface-initiated Kumada catalyst transfer polymerization. In this study, we provided evidence that the surface-initiated polymerization occurs by the highly robust controlled (quasi-“living”) chain-growth mechanism. Further optimization of this method enabled reliable preparation of polythiophene thin films with thickness up to 100 nm. Extensive structural studies of the resulting thin films using X-ray and neutron scattering methods as well as ultraviolet photoemission spectroscopy revealed detailed information on molecular organization and the bulk morphology of the films, and enabled further optimization of the polymerization protocol. One of the remarkable findings was that surface-initiated polymerization delivers polymer thin films showing complex molecular organization, where polythiophene chains assemble into lateral crystalline domains of about 3.2 nm size, with individual polymer chains folded to form in-plane aligned and densely packed oligomeric segments (7-8 thiophene units per each segment) within each domain. Achieving such a complex mesoscale organization is virtually impossible with traditional methods relying on solution processing of presynthesized polymers. Another significant advantage of surface-confined polymer thin films is their remarkable stability toward organic solvents and other processing conditions. In addition to controlled bulk morphology, uniform molecular organization, and stability, a unique feature of the surface-initiated polymerization is that it can be used for the preparation of large-area uniformly nanopatterned polymer thin films. Lastly, this was demonstrated using a combination of particle lithography and surface-initiated polymerization. In general, surface-initiated polymerization is not limited to polythiophene but can be also expanded toward other classes of semiconducting polymers and copolymers.« less

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.

Impact of cleaning methods on the structural properties and morphology of SrTiO3 surface

NASA Astrophysics Data System (ADS)

Arnay, Iciar; Rubio-Zuazo, Juan; Castro, German R.

2018-01-01

SrTiO3 is a widely used substrate for the epitaxial growth of complex systems. Nevertheless, in order to get good quality interface and avoid the formation of defects in the adsorbed layer it is essential to prepare the surface of the substrate prior to the deposition. Thermal and chemical treatments are mostly used to eliminate superficial contamination and improve the surface quality. However, there is a lack of information regarding the impact of these treatments on the formation of structural defects at the SrTiO3 surface. In this work we present a detailed characterization of the SrTiO3 surface for the different cleaning methods paying special attention to the formation of oxygen vacancies, large surface mosaicity and roughness. We prove that thermal treatment induces large surface roughness and that chemical etching produces important structural defects at the surface. Our results show that mechanical polishing provided the best compromise in terms of large surface domains, low roughness, absence of oxygen vacancies and absence of atomic structure modification, although with the presence of low level of contaminants at the SrTiO3 surface.

Catalytic Chemistry on Oxide Nanostructures

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

Asthagiri, Aravind; Dixon, David A.; Dohnalek, Zdenek

2016-05-29

Metal oxides represent one of the most important and widely employed materials in catalysis. Extreme variability of their chemistry provides a unique opportunity to tune their properties and to utilize them for the design of highly active and selective catalysts. For bulk oxides, this can be achieved by varying their stoichiometry, phase, exposed surface facets, defect, dopant densities and numerous other ways. Further, distinct properties from those of bulk oxides can be attained by restricting the oxide dimensionality and preparing them in the form of ultrathin films and nanoclusters as discussed throughout this book. In this chapter we focus onmore » demonstrating such unique catalytic properties brought by the oxide nanoscaling. In the highlighted studies planar models are carefully designed to achieve minimal dispersion of structural motifs and to attain detailed mechanistic understanding of targeted chemical transformations. Detailed level of morphological and structural characterization necessary to achieve this goal is accomplished by employing both high-resolution imaging via scanning probe methods and ensemble-averaged surface sensitive spectroscopic methods. Three prototypical examples illustrating different properties of nanoscaled oxides in different classes of reactions are selected.« less

Interactions between Point Bar Growth and Bank Erosion on a Low Sinuosity Meander Bend in an Ephemeral Channel: Insights from Repeat Topographic Surveys and Numerical Modeling

NASA Astrophysics Data System (ADS)

Ursic, M.; Langendoen, E. J.

2017-12-01

Interactions between point bar growth, bank migration, and hydraulics on meandering rivers are complicated and not well understood. For ephemeral streams, rapid fluctuations in flow further complicate studying and understanding these interactions. This study seeks to answer the following `cause-and-effect' question: Does point bar morphologic adjustment determine where bank erosion occurs (for example, through topographic steering of the flow), or does local bank retreat determine where accretion/erosion occurs on the point bar, or do bank erosion and point bar morphologic adjustment co-evolve? Further, is there a response time between the `cause-and-effect' processes and what variables determine its magnitude and duration? In an effort to answer these questions for an ephemeral stream, a dataset of forty-eight repeat topographic surveys over a ten-year period (1996-2006) of a low sinuosity bend within the Goodwin Creek Experimental Watershed, located near Batesville, MS, were utilized in conjunction with continuous discharge measurements to correlate flow variability and erosional and depositional zones, spatially and temporally. Hydraulically, the bend is located immediately downstream of a confluence with a major tributary. Supercritical flumes on both the primary and tributary channels just upstream of the confluence provide continuous measured discharges to the bend over the survey period. In addition, water surface elevations were continuously measured at the upstream and downstream ends of the bend. No spatial correlation trends could be discerned between reach-scale bank retreat, point bar morphologic adjustment, and flow discharge. Because detailed flow patterns were not available, the two-dimensional computer model Telemac2D was used to provide these details. The model was calibrated and validated for a set of runoff events for which more detailed flow data were available. Telemac2D simulations were created for each topographic survey period. Flows greater than baseflow were combined to create contiguous hydrographs for each survey period. Statistical examination of local flow variability and morphological changes throughout the bend will be conducted and presented.

Morphometric attributes to understand palaeogeomorphological controls on mass-transport deposits offshore Brazil

NASA Astrophysics Data System (ADS)

Piedade, Aldina; Alves, Tiago; Luís Zêzere, José

2017-04-01

Mass-transport deposits form a significant part of the stratigraphic record of ancient and modern deep-water basins worldwide. Three-dimensional (3D) seismic data is used to analyse two different types of buried mass-transport deposits offshore Espírito Santo Basin (SE Brazil. Both types are developed within Early Miocene to Holocene stratigraphic units composed of sandstones, calcarenites, turbidite sands and marls. The high resolution images provided by the interpreted 3D seismic data allowed a detailed analysis of the seismic stratigraphy and internal structure of mass-transport deposits. In addition, improvements in visualisation techniques were used to compute simple morphometric attributes of buried mass-transport deposits in continental slopes. This study classifies the interpreted mass-transport deposits in two different types according to the relationship between the morphology of mass-transport deposits and the surrounding topography. Locally confined mass-transport deposits are laterally constrained by non-deformed strata that surrounds the mass-transport deposit and by the local topography of the depositional surface. Their dimensions are relatively small (area of 5.251 km2). Unconfined mass-transport deposits show a much larger volume compared to the previously type ( 87.180 km2), and local topography does not have control on their geometry. The analysis proves that local topography and geometry of the depositional surface are key controlling factors on the spatial distribution and dimensions of the two types of mass-transport deposits. However, the two types differ in size, geomorphological expression, local structural controls and run-out distance. This work importance is relate variations in the character of the depositional surface with the morphology mass-transport deposits and run-out distance. As a result of the methodology used, two different styles of mass-transport run-out are identified and local factors controlling their morphology are addressed, such as roughness and local morphology of the depositional surface. Separating these two styles, or types, of mass-transport deposits it is of critical importance to understand their mechanisms of gliding, downslope spreading and emplacement.

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.

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

Ayala, Alicia; Corral, Erica L.; Loehman, Ronald E.

A tape casting procedure for fabricating ceramic magnesium oxide tapes has been developed as a method to produce flat sheets of sintered MgO that are thin and porous. Thickness of single layer tapes is in the range of 200-400 {micro}m with corresponding surface roughness values in the range of 10-20 {micro}m as measured by laser profilometry. Development of the tape casting technique required optimization of pretreatment for the starting magnesium oxide (MgO) powder as well as a detailed study of the casting slurry preparation and subsequent heat treatments for sintering and final tape flattening. Milling time of the ceramic powder,more » plasticizer, and binder mixture was identified as a primary factor affecting surface morphology of the tapes. In general, longer milling times resulted in green tapes with a noticeably smoother surface. This work demonstrates that meticulous control of the entire tape casting operation is necessary to obtain high-quality MgO tapes.« less

High-speed micro-scale laser shock peening using a fiber laser (Conference Presentation)

NASA Astrophysics Data System (ADS)

Zhang, Chenfei; Deng, Leimin; Sun, Shiding; Lu, Yongfeng

2017-03-01

Laser shock peening using low-energy nanosecond (ns) fiber lasers was investigated in this study to realize high-speed micro-scale laser shock peening on selected positions without causing surface damage. Due to the employment of a fiber laser with high-frequency and prominent environmental adaptability, the laser peening system is able to work with a much higher speed compared to traditional peening systems using Nd:YAG lasers and is promising for in-situ applications in harsh environments. Detailed surface morphology investigations both on sacrificial coatings and Al alloy surfaces after the fiber laser peening revealed the effects of focal position, pulse duration, peak power density, and impact times. Micro-dent arrays were also obtained with different spot-to-spot distances. Obvious micro-hardness improvement was observed inside the laser-peening-induced microdents after the fiber laser shock peening.

Geologic remote sensing - New technology, new information

NASA Technical Reports Server (NTRS)

Kruse, F. A.

1992-01-01

Results of geologic studies using data collected by the NASA/JPL Thermal Infrared Imaging Spectrometer (TIMS), Airborne Visible/Infrared Imaging Spectrometer (AVIRIS), and the Airborne Synthetic Aperture Radar (AIRSAR) are discussed. These instruments represent prototypes for the Earth Observing System (EOS) satellite instruments ASTER, High Resolution Imaging Spectrometer (HIRIS), and EOS SAR. Integrated analysis of this data type is one of the keys to successful geologic research using EOS. TIMS links the physical properties of surface materials in the 8-12-*mm region to their composition. Calibrated aircraft data make direct lithological mapping possible. AVIRIS, an analog for HIRIS, provides quantitative information about the surface composition of materials based on their detailed visible and infrared spectral signatures (0.4-2.45 mm). Calibrated AVIRIS data make direct identification of minerals possible. The AIRSAR provides additional complementary information about the surface morphology of rocks and soils.

Morphological features of the macerated cranial bones registered by the 3D vision system for potential use in forensic anthropology.

PubMed

Skrzat, Janusz; Sioma, Andrzej; Kozerska, Magdalena

2013-01-01

In this paper we present potential usage of the 3D vision system for registering features of the macerated cranial bones. Applied 3D vision system collects height profiles of the object surface and from that data builds a three-dimensional image of the surface. This method appeared to be accurate enough to capture anatomical details of the macerated bones. With the aid of the 3D vision system we generated images of the surface of the human calvaria which was used for testing the system. Performed reconstruction visualized the imprints of the dural vascular system, cranial sutures, and the three-layer structure of the cranial bones observed in the cross-section. We figure out that the 3D vision system may deliver data which can enhance estimation of sex from the osteological material.

Cryptic or pseudocryptic: can morphological methods inform copepod taxonomy? An analysis of publications and a case study of the Eurytemora affinis species complex

PubMed Central

Lajus, Dmitry; Sukhikh, Natalia; Alekseev, Victor

2015-01-01

Interest in cryptic species has increased significantly with current progress in genetic methods. The large number of cryptic species suggests that the resolution of traditional morphological techniques may be insufficient for taxonomical research. However, some species now considered to be cryptic may, in fact, be designated pseudocryptic after close morphological examination. Thus the “cryptic or pseudocryptic” dilemma speaks to the resolution of morphological analysis and its utility for identifying species. We address this dilemma first by systematically reviewing data published from 1980 to 2013 on cryptic species of Copepoda and then by performing an in-depth morphological study of the former Eurytemora affinis complex of cryptic species. Analyzing the published data showed that, in 5 of 24 revisions eligible for systematic review, cryptic species assignment was based solely on the genetic variation of forms without detailed morphological analysis to confirm the assignment. Therefore, some newly described cryptic species might be designated pseudocryptic under more detailed morphological analysis as happened with Eurytemora affinis complex. Recent genetic analyses of the complex found high levels of heterogeneity without morphological differences; it is argued to be cryptic. However, next detailed morphological analyses allowed to describe a number of valid species. Our study, using deep statistical analyses usually not applied for new species describing, of this species complex confirmed considerable differences between former cryptic species. In particular, fluctuating asymmetry (FA), the random variation of left and right structures, was significantly different between forms and provided independent information about their status. Our work showed that multivariate statistical approaches, such as principal component analysis, can be powerful techniques for the morphological discrimination of cryptic taxons. Despite increasing cryptic species designations, morphological techniques have great potential in determining copepod taxonomy. PMID:26120427

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.

Exceptionally crystalline and conducting acid doped polyaniline films by level surface assisted solution casting approach

NASA Astrophysics Data System (ADS)

Puthirath, Anand B.; Methattel Raman, Shijeesh; Varma, Sreekanth J.; Jayalekshmi, S.

2016-04-01

Emeraldine salt form of polyaniline (PANI) was synthesized by chemical oxidative polymerisation method using ammonium persulfate as oxidant. Resultant emeraldine salt form of PANI was dedoped using ammonia solution and then re-doped with camphor sulphonic acid (CSA), naphthaline sulphonic acid (NSA), hydrochloric acid (HCl), and m-cresol. Thin films of these doped PANI samples were deposited on glass substrates using solution casting method with m-cresol as solvent. A level surface was employed to get homogeneous thin films of uniform thickness. Detailed X-ray diffraction studies have shown that the films are exceptionally crystalline. The crystalline peaks observed in the XRD spectra can be indexed to simple monoclinic structure. FTIR and Raman spectroscopy studies provide convincing explanation for the exceptional crystallinity observed in these polymer films. FESEM and AFM images give better details of surface morphology of doped PANI films. The DC electrical conductivity of the samples was measured using four point probe technique. It is seen that the samples also exhibit quite high DC electrical conductivity, about 287 S/cm for CSA doped PANI, 67 S/cm for NSA doped PANI 65 S/cm for HCl doped PANI, and just below 1 S/cm for m-cresol doped PANI. Effect of using the level surface for solution casting is studied and correlated with the observed crystallinity.

Exceptionally crystalline and conducting acid doped polyaniline films by level surface assisted solution casting approach

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

Puthirath, Anand B.; Varma, Sreekanth J.; Jayalekshmi, S., E-mail: jayalekshmi@cusat.ac.in

2016-04-18

Emeraldine salt form of polyaniline (PANI) was synthesized by chemical oxidative polymerisation method using ammonium persulfate as oxidant. Resultant emeraldine salt form of PANI was dedoped using ammonia solution and then re-doped with camphor sulphonic acid (CSA), naphthaline sulphonic acid (NSA), hydrochloric acid (HCl), and m-cresol. Thin films of these doped PANI samples were deposited on glass substrates using solution casting method with m-cresol as solvent. A level surface was employed to get homogeneous thin films of uniform thickness. Detailed X-ray diffraction studies have shown that the films are exceptionally crystalline. The crystalline peaks observed in the XRD spectra canmore » be indexed to simple monoclinic structure. FTIR and Raman spectroscopy studies provide convincing explanation for the exceptional crystallinity observed in these polymer films. FESEM and AFM images give better details of surface morphology of doped PANI films. The DC electrical conductivity of the samples was measured using four point probe technique. It is seen that the samples also exhibit quite high DC electrical conductivity, about 287 S/cm for CSA doped PANI, 67 S/cm for NSA doped PANI 65 S/cm for HCl doped PANI, and just below 1 S/cm for m-cresol doped PANI. Effect of using the level surface for solution casting is studied and correlated with the observed crystallinity.« less

Three-dimensional morphology of heel fat pad: an in vivo computed tomography study.

PubMed

Campanelli, Valentina; Fantini, Massimiliano; Faccioli, Niccolò; Cangemi, Alessio; Pozzo, Antonio; Sbarbati, Andrea

2011-11-01

Heel fat pad cushioning efficiency is the result of its structure, shape and thickness. However, while a number of studies have investigated heel fat pad (HFP) anatomy, structural behavior and material properties, no previous study has described its three-dimensional morphology in situ. The assessment of the healthy, unloaded, three-dimensional morphology of heel pad may contribute to deepen the understanding of its role and behavior during locomotion. It is the basis for the assessment of possible HFP morphological modifications due to changes in the amount or distribution of the loads normally sustained by the foot. It may also help in guiding the surgical reconstruction of the pad and in improving footwear design, as well as in developing a correct heel pad geometry for finite element models of the foot. Therefore the purpose of this study was to obtain a complete analysis of HFP three-dimensional morphology in situ. The right foot of nine healthy volunteers was scanned with computed tomography. A methodological approach that maximizes reliability and repeatability of the data was developed by building a device to lock the foot in a neutral position with respect to the scan planes during image acquisition. Scan data were used to reconstruct virtual three-dimensional models for both the calcaneus and HFP. A set of virtual coronal and axial sections were extracted from the three-dimensional model of each HFP and processed to extract a set of one- and two-dimensional morphometrical measurements for a detailed description of heel pad morphology. The tissue exhibited a consistent and sophisticated morphology that may reflect the biomechanics of the foot support. HFP was found to be have a crest on its anterior dorsal surface, flanges on the sides and posteriorly, and a thick portion that reached and covered the posterior surface of the calcaneus and the achilles tendon insertion. Its anterior internal portion was thinner and a lump of fat was consistently present in this region. Finally, HFP was found to be thicker in males than in females. © 2011 The Authors. Journal of Anatomy © 2011 Anatomical Society of Great Britain and Ireland.

Three-dimensional morphology of heel fat pad: an in vivo computed tomography study

PubMed Central

Campanelli, Valentina; Fantini, Massimiliano; Faccioli, Niccolò; Cangemi, Alessio; Pozzo, Antonio; Sbarbati, Andrea

2011-01-01

Heel fat pad cushioning efficiency is the result of its structure, shape and thickness. However, while a number of studies have investigated heel fat pad (HFP) anatomy, structural behavior and material properties, no previous study has described its three-dimensional morphology in situ. The assessment of the healthy, unloaded, three-dimensional morphology of heel pad may contribute to deepen the understanding of its role and behavior during locomotion. It is the basis for the assessment of possible HFP morphological modifications due to changes in the amount or distribution of the loads normally sustained by the foot. It may also help in guiding the surgical reconstruction of the pad and in improving footwear design, as well as in developing a correct heel pad geometry for finite element models of the foot. Therefore the purpose of this study was to obtain a complete analysis of HFP three-dimensional morphology in situ. The right foot of nine healthy volunteers was scanned with computed tomography. A methodological approach that maximizes reliability and repeatability of the data was developed by building a device to lock the foot in a neutral position with respect to the scan planes during image acquisition. Scan data were used to reconstruct virtual three-dimensional models for both the calcaneus and HFP. A set of virtual coronal and axial sections were extracted from the three-dimensional model of each HFP and processed to extract a set of one- and two-dimensional morphometrical measurements for a detailed description of heel pad morphology. The tissue exhibited a consistent and sophisticated morphology that may reflect the biomechanics of the foot support. HFP was found to be have a crest on its anterior dorsal surface, flanges on the sides and posteriorly, and a thick portion that reached and covered the posterior surface of the calcaneus and the achilles tendon insertion. Its anterior internal portion was thinner and a lump of fat was consistently present in this region. Finally, HFP was found to be thicker in males than in females. PMID:21848602

Spatially Resolved Quantification of the Surface Reactivity of Solid Catalysts.

PubMed

Huang, Bing; Xiao, Li; Lu, Juntao; Zhuang, Lin

2016-05-17

A new property is reported that accurately quantifies and spatially describes the chemical reactivity of solid surfaces. The core idea is to create a reactivity weight function peaking at the Fermi level, thereby determining a weighted summation of the density of states of a solid surface. When such a weight function is defined as the derivative of the Fermi-Dirac distribution function at a certain non-zero temperature, the resulting property is the finite-temperature chemical softness, termed Fermi softness (SF ), which turns out to be an accurate descriptor of the surface reactivity. The spatial image of SF maps the reactive domain of a heterogeneous surface and even portrays morphological details of the reactive sites. SF analyses reveal that the reactive zones on a Pt3 Y(111) surface are the platinum sites rather than the seemingly active yttrium sites, and the reactivity of the S-dimer edge of MoS2 is spatially anisotropic. Our finding is of fundamental and technological significance to heterogeneous catalysis and industrial processes demanding rational design of solid catalysts. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Aging effects on vertical graphene nanosheets and their thermal stability

NASA Astrophysics Data System (ADS)

Ghosh, S.; Polaki, S. R.; Ajikumar, P. K.; Krishna, N. G.; Kamruddin, M.

2018-03-01

The present study investigates environmental aging effects and thermal stability of vertical graphene nanosheets (VGN). Self-organized VGN is synthesized by plasma enhanced chemical vapor deposition and exposed to ambient conditions over 6-month period to examine its aging behavior. A systematic inspection is carried out on morphology, chemical structure, wettability and electrical property by scanning electron microscopy, Raman spectroscopy, X-ray photoelectron spectroscopy, water contact angle and four-probe resistivity measurements at regular intervals, respectively. Detailed microscopic and spectroscopic analysis substantiated the retention of graphitic quality and surface chemistry of VGN over the test period. An unchanged sheet resistance and hydrophobicity reveals its electrical and wetting stability over the time, respectively. Thermogravimetric analysis ensures an excellent thermal stability of VGN up to 575 °C in ambient atmosphere. These findings of long-term morphological, structural, wetting, electrical and thermal stability of VGN validate their potential utilization for the next-generation device applications.

Recent progress in hollow sphere-based electrodes for high-performance supercapacitors

NASA Astrophysics Data System (ADS)

Zhao, Yan; Chen, Min; Wu, Limin

2016-08-01

Hollow spheres have drawn much attention in the area of energy storage and conversion, especially in high-performance supercapacitors owing to their well-defined morphologies, uniform size, low density and large surface area. And quite some significant breakthroughs have been made in advanced supercapacitor electrode materials with hollow sphere structures. In this review, we summarize and discuss the synthesis and application of hollow spheres with controllable structure and morphology as electrode materials for supercapacitors. First, we briefly introduce the fabrication strategies of hollow spheres for electrode materials. Then, we discuss in detail the recent advances in various hollow sphere-based electrode materials for supercapacitors, including single-shelled, yolk-shelled, urchin-like, double-shelled, multi-shelled, and mesoporous hollow structure-based symmetric and asymmetric supercapacitor devices. We conclude this review with some perspectives on the future research and development of the hollow sphere-based electrode materials.

Symmetry breaking and electrical frustration during tip-induced polarization switching in the non-polar cut of lithium niobate single crystals

DOE PAGES

Ievlev, Anton; Alikin, Denis O.; Morozovska, A. N.; ...

2014-12-15

Polarization switching in ferroelectric materials is governed by a delicate interplay between bulk polarization dynamics and screening processes at surfaces and domain walls. Here we explore the mechanism of tip-induced polarization switching in the non-polar cuts of uniaxial ferroelectrics. In this case, in-plane component of polarization vector switches, allowing for detailed observations of resultant domain morphologies. We observe surprising variability of resultant domain morphologies stemming from fundamental instability of formed charged domain wall and associated electric frustration. In particular, we demonstrate that controlling vertical tip position allows the polarity of the switching to be controlled. This represents very unusual formmore » of symmetry breaking where mechanical motion in vertical direction controls the lateral domain growth. The implication of these studies for ferroelectric devices and domain wall electronics are discussed.« less

PDMS substrate stiffness affects the morphology and growth profiles of cancerous prostate and melanoma cells.

PubMed

Prauzner-Bechcicki, Szymon; Raczkowska, Joanna; Madej, Ewelina; Pabijan, Joanna; Lukes, Jaroslav; Sepitka, Josef; Rysz, Jakub; Awsiuk, Kamil; Bernasik, Andrzej; Budkowski, Andrzej; Lekka, Małgorzata

2015-01-01

A deep understanding of the interaction between cancerous cells and surfaces is particularly important for the design of lab-on-chip devices involving the use of polydimethylsiloxane (PDMS). In our studies, the effect of PDMS substrate stiffness on mechanical properties of cancerous cells was investigated in conditions where the PDMS substrate is not covered with any of extracellular matrix proteins. Two human prostate cancer (Du145 and PC-3) and two melanoma (WM115 and WM266-4) cell lines were cultured on two groups of PDMS substrates that were characterized by distinct stiffness, i.e. 0.75 ± 0.06 MPa and 2.92 ± 0.12 MPa. The results showed the strong effect on cellular behavior and morphology. The detailed analysis of chemical and physical properties of substrates revealed that cellular behavior occurs only due to substrate elasticity. Copyright © 2014 Elsevier Ltd. All rights reserved.

Recent progress in hollow sphere-based electrodes for high-performance supercapacitors.

PubMed

Zhao, Yan; Chen, Min; Wu, Limin

2016-08-26

Hollow spheres have drawn much attention in the area of energy storage and conversion, especially in high-performance supercapacitors owing to their well-defined morphologies, uniform size, low density and large surface area. And quite some significant breakthroughs have been made in advanced supercapacitor electrode materials with hollow sphere structures. In this review, we summarize and discuss the synthesis and application of hollow spheres with controllable structure and morphology as electrode materials for supercapacitors. First, we briefly introduce the fabrication strategies of hollow spheres for electrode materials. Then, we discuss in detail the recent advances in various hollow sphere-based electrode materials for supercapacitors, including single-shelled, yolk-shelled, urchin-like, double-shelled, multi-shelled, and mesoporous hollow structure-based symmetric and asymmetric supercapacitor devices. We conclude this review with some perspectives on the future research and development of the hollow sphere-based electrode materials.

Single Crystals Grown Under Unconstrained Conditions

NASA Astrophysics Data System (ADS)

Sunagawa, Ichiro

Based on detailed investigations on morphology (evolution and variation in external forms), surface microtopography of crystal faces (spirals and etch figures), internal morphology (growth sectors, growth banding and associated impurity partitioning) and perfection (dislocations and other lattice defects) in single crystals, we can deduce how and by what mechanism the crystal grew and experienced fluctuation in growth parameters through its growth and post-growth history under unconstrained condition. The information is useful not only in finding appropriate way to growing highly perfect and homogeneous single crystals, but also in deciphering letters sent from the depth of the Earth and the Space. It is also useful in discriminating synthetic from natural gemstones. In this chapter, available methods to obtain molecular information are briefly summarized, and actual examples to demonstrate the importance of this type of investigations are selected from both natural minerals (diamond, quartz, hematite, corundum, beryl, phlogopite) and synthetic crystals (SiC, diamond, corundum, beryl).

Synchrotron In-Situ Aging Study and Correlations to the γ' Phase Instabilities in a High-Refractory Content γ-γ' Ni-Base Superalloy

NASA Astrophysics Data System (ADS)

Antonov, Stoichko; Sun, Eugene; Tin, Sammy

2018-06-01

Detailed ex-situ electron microscopy and atom probe tomography (APT) were combined with in-situ synchrotron diffraction to systematically quantify the chemical, morphological, and lattice instabilities that occur during aging of a polycrystalline high-refractory content Ni-base superalloy. The morphological changes and splitting phenomenon associated with the secondary γ' precipitates were related to a combination of discrete chemical composition variations at the secondary γ'/γ interfaces and additional chemical energy arising from γ precipitates that form within the secondary γ' particles. The compositional phase inhomogeneities led to the precipitation of finely dispersed tertiary γ' particles within the γ matrix and secondary γ particles within the secondary γ' precipitates, which, along with surface grooving of the secondary γ' particles, likely due to a spike in the lattice misfit at the particle interfaces, contributed to the splitting of the precipitates during aging.

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

Youm, Sang Gil; Hwang, Euiyong; Chavez, Carlos A.

The ability to control nanoscale morphology and molecular organization in organic semiconducting polymer thin films is an important prerequisite for enhancing the efficiency of organic thin-film devices including organic light-emitting and photovoltaic devices. The current “top-down” paradigm for making such devices is based on utilizing solution-based processing (e.g., spin-casting) of soluble semiconducting polymers. This approach typically provides only modest control over nanoscale molecular organization and polymer chain alignment. A promising alternative to using solutions of presynthesized semiconducting polymers pursues instead a “bottom-up” approach to prepare surface-grafted semiconducting polymer thin films by surface-initiated polymerization of small-molecule monomers. Herein, we describe themore » development of an efficient method to prepare polythiophene thin films utilizing surface-initiated Kumada catalyst transfer polymerization. In this study, we provided evidence that the surface-initiated polymerization occurs by the highly robust controlled (quasi-“living”) chain-growth mechanism. Further optimization of this method enabled reliable preparation of polythiophene thin films with thickness up to 100 nm. Extensive structural studies of the resulting thin films using X-ray and neutron scattering methods as well as ultraviolet photoemission spectroscopy revealed detailed information on molecular organization and the bulk morphology of the films, and enabled further optimization of the polymerization protocol. One of the remarkable findings was that surface-initiated polymerization delivers polymer thin films showing complex molecular organization, where polythiophene chains assemble into lateral crystalline domains of about 3.2 nm size, with individual polymer chains folded to form in-plane aligned and densely packed oligomeric segments (7-8 thiophene units per each segment) within each domain. Achieving such a complex mesoscale organization is virtually impossible with traditional methods relying on solution processing of presynthesized polymers. Another significant advantage of surface-confined polymer thin films is their remarkable stability toward organic solvents and other processing conditions. In addition to controlled bulk morphology, uniform molecular organization, and stability, a unique feature of the surface-initiated polymerization is that it can be used for the preparation of large-area uniformly nanopatterned polymer thin films. Lastly, this was demonstrated using a combination of particle lithography and surface-initiated polymerization. In general, surface-initiated polymerization is not limited to polythiophene but can be also expanded toward other classes of semiconducting polymers and copolymers.« less

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

Topography of the 81/P Wild 2 Nucleus Derived from Stardust Stereoimages

NASA Technical Reports Server (NTRS)

Kirk, R. L.; Duxbury, T. C.; Horz, F.; Brownlee, D. E.; Newburn, R. L.; Tsou, P.

2005-01-01

On 2 January, 2004, the Stardust spacecraft flew by the nucleus of comet 81P/Wild 2 with a closest approach distance of approx. 240 km. During the encounter, the Stardust Optical Navigation Camera (ONC) obtained 72 images of the nucleus with exposure times alternating between 10 ms (near-optimal for most of the nucleus surface) and 100 ms (used for navigation, and revealing additional details in the coma and dark portions of the surface. Phase angles varied from 72 deg. to near zero to 103 deg. during the encounter, allowing the entire sunlit portion of the surface to be imaged. As many as 20 of the images near closest approach are of sufficiently high resolution to be used in mapping the nucleus surface; of these, two pairs of short-exposure images were used to create the nucleus shape model and derived products reported here. The best image resolution obtained was approx. 14 m/pixel, resulting in approx. 300 pixels across the nucleus. The Stardust Wild 2 dataset is therefore markedly superior from a stereomapping perspective to the Deep Space 1 MICAS images of comet Borrelly. The key subset of the latter (3 images) covered only about a quarter of the surface at phase angles approx. 50 - 60 and less than 50 x 160 pixels across the nucleus, yet it sufficed for groups at the USGS and DLR to produce digital elevation models (DEMs) and study the morphology and photometry of the nucleus in detail.

Imaging Asteroid 4 Vesta Using the Framing Camera

NASA Technical Reports Server (NTRS)

Keller, H. Uwe; Nathues, Andreas; Coradini, Angioletta; Jaumann, Ralf; Jorda, Laurent; Li, Jian-Yang; Mittlefehldt, David W.; Mottola, Stefano; Raymond, C. A.; Schroeder, Stefan E.

2011-01-01

The Framing Camera (FC) onboard the Dawn spacecraft serves a dual purpose. Next to its central role as a prime science instrument it is also used for the complex navigation of the ion drive spacecraft. The CCD detector with 1024 by 1024 pixels provides the stability for a multiyear mission and its high requirements of photometric accuracy over the wavelength band from 400 to 1000 nm covered by 7 band-pass filters. Vesta will be observed from 3 orbit stages with image scales of 227, 63, and 17 m/px, respectively. The mapping of Vesta s surface with medium resolution will be only completed during the exit phase when the north pole will be illuminated. A detailed pointing strategy will cover the surface at least twice at similar phase angles to provide stereo views for reconstruction of the topography. During approach the phase function of Vesta was determined over a range of angles not accessible from earth. This is the first step in deriving the photometric function of the surface. Combining the topography based on stereo tie points with the photometry in an iterative procedure will disclose details of the surface morphology at considerably smaller scales than the pixel scale. The 7 color filters are well positioned to provide information on the spectral slope in the visible, the depth of the strong pyroxene absorption band, and their variability over the surface. Cross calibration with the VIR spectrometer that extends into the near IR will provide detailed maps of Vesta s surface mineralogy and physical properties. Georeferencing all these observation will result in a coherent and unique data set. During Dawn s approach and capture FC has already demonstrated its performance. The strong variation observed by the Hubble Space Telescope can now be correlated with surface units and features. We will report on results obtained from images taken during survey mode covering the whole illuminated surface. Vesta is a planet-like differentiated body, but its surface gravity and escape velocity are comparable to those of other asteroids and hence much smaller than those of the inner planets or

Structure and morphology of magnetron sputter deposited ultrathin ZnO films on confined polymeric template

NASA Astrophysics Data System (ADS)

Singh, Ajaib; Schipmann, Susanne; Mathur, Aakash; Pal, Dipayan; Sengupta, Amartya; Klemradt, Uwe; Chattopadhyay, Sudeshna

2017-08-01

The structure and morphology of ultra-thin zinc oxide (ZnO) films with different film thicknesses on confined polymer template were studied through X-ray reflectivity (XRR) and grazing incidence small angle X-ray scattering (GISAXS). Using magnetron sputter deposition technique ZnO thin films with different film thicknesses (<10 nm) were grown on confined polystyrene with ∼2Rg film thickness, where Rg ∼ 20 nm (Rg is the unperturbed radius of gyration of polystyrene, defined by Rg = 0.272 √M0, and M0 is the molecular weight of polystyrene). The detailed internal structure, along the surface/interfaces and the growth direction of the system were explored in this study, which provides insight into the growth procedure of ZnO on confined polymer and reveals that a thin layer of ZnO, with very low surface and interface roughness, can be grown by DC magnetron sputtering technique, with approximately full coverage (with bulk like electron density) even in nm order of thickness, in 2-7 nm range on confined polymer template, without disturbing the structure of the underneath template. The resulting ZnO-polystyrene hybrid systems show strong ZnO near band edge (NBE) and deep-level (DLE) emissions in their room temperature photoluminescence spectra, where the contribution of DLE gets relatively stronger with decreasing ZnO film thickness, indicating a significant enhancement of surface defects because of the greater surface to volume ratio in thinner films.

Arsia Mons by Day and Night

NASA Image and Video Library

2004-06-22

Released 22 June 2004 This pair of images shows part of Arsia Mons. Day/Night Infrared Pairs The image pairs presented focus on a single surface feature as seen in both the daytime and nighttime by the infrared THEMIS camera. The nighttime image (right) has been rotated 180 degrees to place north at the top. Infrared image interpretation Daytime: Infrared images taken during the daytime exhibit both the morphological and thermophysical properties of the surface of Mars. Morphologic details are visible due to the effect of sun-facing slopes receiving more energy than antisun-facing slopes. This creates a warm (bright) slope and cool (dark) slope appearance that mimics the light and shadows of a visible wavelength image. Thermophysical properties are seen in that dust heats up more quickly than rocks. Thus dusty areas are bright and rocky areas are dark. Nighttime: Infrared images taken during the nighttime exhibit only the thermophysical properties of the surface of Mars. The effect of sun-facing versus non-sun-facing energy dissipates quickly at night. Thermophysical effects dominate as different surfaces cool at different rates through the nighttime hours. Rocks cool slowly, and are therefore relatively bright at night (remember that rocks are dark during the day). Dust and other fine grained materials cool very quickly and are dark in nighttime infrared images. Image information: IR instrument. Latitude -19.6, Longitude 241.9 East (118.1 West). 100 meter/pixel resolution. http://photojournal.jpl.nasa.gov/catalog/PIA06399

Crater Ejecta by Day and Night

NASA Image and Video Library

2004-06-24

Released 24 June 2004 This pair of images shows a crater and its ejecta. Day/Night Infrared Pairs The image pairs presented focus on a single surface feature as seen in both the daytime and nighttime by the infrared THEMIS camera. The nighttime image (right) has been rotated 180 degrees to place north at the top. Infrared image interpretation Daytime: Infrared images taken during the daytime exhibit both the morphological and thermophysical properties of the surface of Mars. Morphologic details are visible due to the effect of sun-facing slopes receiving more energy than antisun-facing slopes. This creates a warm (bright) slope and cool (dark) slope appearance that mimics the light and shadows of a visible wavelength image. Thermophysical properties are seen in that dust heats up more quickly than rocks. Thus dusty areas are bright and rocky areas are dark. Nighttime: Infrared images taken during the nighttime exhibit only the thermophysical properties of the surface of Mars. The effect of sun-facing versus non-sun-facing energy dissipates quickly at night. Thermophysical effects dominate as different surfaces cool at different rates through the nighttime hours. Rocks cool slowly, and are therefore relatively bright at night (remember that rocks are dark during the day). Dust and other fine grained materials cool very quickly and are dark in nighttime infrared images. Image information: IR instrument. Latitude -9, Longitude 164.2 East (195.8 West). 100 meter/pixel resolution. http://photojournal.jpl.nasa.gov/catalog/PIA06445

Microstructures and growth mechanisms of GaN films epitaxially grown on AlN/Si hetero-structures by pulsed laser deposition at different temperatures

PubMed Central

Wang, Wenliang; Yang, Weijia; Lin, Yunhao; Zhou, Shizhong; Li, Guoqiang

2015-01-01

2 inch-diameter GaN films with homogeneous thickness distribution have been grown on AlN/Si(111) hetero-structures by pulsed laser deposition (PLD) with laser rastering technique. The surface morphology, crystalline quality, and interfacial property of as-grown GaN films are characterized in detail. By optimizing the laser rastering program, the ~300 nm-thick GaN films grown at 750 °C show a root-mean-square (RMS) thickness inhomogeneity of 3.0%, very smooth surface with a RMS surface roughness of 3.0 nm, full-width at half-maximums (FWHMs) for GaN(0002) and GaN(102) X-ray rocking curves of 0.7° and 0.8°, respectively, and sharp and abrupt AlN/GaN hetero-interfaces. With the increase in the growth temperature from 550 to 850 °C, the surface morphology, crystalline quality, and interfacial property of as-grown ~300 nm-thick GaN films are gradually improved at first and then decreased. Based on the characterizations, the corresponding growth mechanisms of GaN films grown on AlN/Si hetero-structures by PLD with various growth temperatures are hence proposed. This work would be beneficial to understanding the further insight of the GaN films grown on Si(111) substrates by PLD for the application of GaN-based devices. PMID:26563573

1D-3D hybrid modeling-from multi-compartment models to full resolution models in space and time.

PubMed

Grein, Stephan; Stepniewski, Martin; Reiter, Sebastian; Knodel, Markus M; Queisser, Gillian

2014-01-01

Investigation of cellular and network dynamics in the brain by means of modeling and simulation has evolved into a highly interdisciplinary field, that uses sophisticated modeling and simulation approaches to understand distinct areas of brain function. Depending on the underlying complexity, these models vary in their level of detail, in order to cope with the attached computational cost. Hence for large network simulations, single neurons are typically reduced to time-dependent signal processors, dismissing the spatial aspect of each cell. For single cell or networks with relatively small numbers of neurons, general purpose simulators allow for space and time-dependent simulations of electrical signal processing, based on the cable equation theory. An emerging field in Computational Neuroscience encompasses a new level of detail by incorporating the full three-dimensional morphology of cells and organelles into three-dimensional, space and time-dependent, simulations. While every approach has its advantages and limitations, such as computational cost, integrated and methods-spanning simulation approaches, depending on the network size could establish new ways to investigate the brain. In this paper we present a hybrid simulation approach, that makes use of reduced 1D-models using e.g., the NEURON simulator-which couples to fully resolved models for simulating cellular and sub-cellular dynamics, including the detailed three-dimensional morphology of neurons and organelles. In order to couple 1D- and 3D-simulations, we present a geometry-, membrane potential- and intracellular concentration mapping framework, with which graph- based morphologies, e.g., in the swc- or hoc-format, are mapped to full surface and volume representations of the neuron and computational data from 1D-simulations can be used as boundary conditions for full 3D simulations and vice versa. Thus, established models and data, based on general purpose 1D-simulators, can be directly coupled to the emerging field of fully resolved, highly detailed 3D-modeling approaches. We present the developed general framework for 1D/3D hybrid modeling and apply it to investigate electrically active neurons and their intracellular spatio-temporal calcium dynamics.

1D-3D hybrid modeling—from multi-compartment models to full resolution models in space and time

PubMed Central

Grein, Stephan; Stepniewski, Martin; Reiter, Sebastian; Knodel, Markus M.; Queisser, Gillian

2014-01-01

Investigation of cellular and network dynamics in the brain by means of modeling and simulation has evolved into a highly interdisciplinary field, that uses sophisticated modeling and simulation approaches to understand distinct areas of brain function. Depending on the underlying complexity, these models vary in their level of detail, in order to cope with the attached computational cost. Hence for large network simulations, single neurons are typically reduced to time-dependent signal processors, dismissing the spatial aspect of each cell. For single cell or networks with relatively small numbers of neurons, general purpose simulators allow for space and time-dependent simulations of electrical signal processing, based on the cable equation theory. An emerging field in Computational Neuroscience encompasses a new level of detail by incorporating the full three-dimensional morphology of cells and organelles into three-dimensional, space and time-dependent, simulations. While every approach has its advantages and limitations, such as computational cost, integrated and methods-spanning simulation approaches, depending on the network size could establish new ways to investigate the brain. In this paper we present a hybrid simulation approach, that makes use of reduced 1D-models using e.g., the NEURON simulator—which couples to fully resolved models for simulating cellular and sub-cellular dynamics, including the detailed three-dimensional morphology of neurons and organelles. In order to couple 1D- and 3D-simulations, we present a geometry-, membrane potential- and intracellular concentration mapping framework, with which graph- based morphologies, e.g., in the swc- or hoc-format, are mapped to full surface and volume representations of the neuron and computational data from 1D-simulations can be used as boundary conditions for full 3D simulations and vice versa. Thus, established models and data, based on general purpose 1D-simulators, can be directly coupled to the emerging field of fully resolved, highly detailed 3D-modeling approaches. We present the developed general framework for 1D/3D hybrid modeling and apply it to investigate electrically active neurons and their intracellular spatio-temporal calcium dynamics. PMID:25120463

An ethanol-based fixation method for anatomical and micro-morphological characterization of leaves of various tree species.

PubMed

Chieco, C; Rotondi, A; Morrone, L; Rapparini, F; Baraldi, R

2013-02-01

The use of formalin constitutes serious health hazards for laboratory workers. We investigated the suitability and performance of the ethanol-based fixative, FineFIX, as a substitute for formalin for anatomical and cellular structure investigations of leaves by light microscopy and for leaf surface and ultrastructural analysis by scanning electron microscopy (SEM). We compared the anatomical features of leaf materials prepared using conventional formalin fixation with the FineFIX. Leaves were collected from ornamental tree species commonly used in urban areas. FineFIX was also compared with glutaraldehyde fixation and air drying normally used for scanning electron microscopy to develop a new method for evaluating leaf morphology and microstructure in three ornamental tree species. The cytological features of the samples processed for histological analysis were well preserved by both fixatives as demonstrated by the absence of nuclear swelling or shrinkage, cell wall detachment or tissue flaking, and good presentation of cytoplasmic vacuolization. In addition, good preservation of surface details and the absence of shrinkage artefacts confirmed the efficacy of FineFIX fixation for SEM analysis. Cuticular wax was preserved only in air dried samples. Samples treated with chemical substances during the fixation and dehydration phases showed various alterations of the wax structures. In some air dried samples a loss of turgidity of the cells was observed that caused general wrinkling of the epidermal surfaces. Commercial FineFIX is an adequate substitute for formalin in histology and it can be applied successfully also for SEM investigation, while reducing the health risks of glutaraldehyde or other toxic fixatives. To investigate the potential for plants to absorb and capture particulates in air, which requires preservation of the natural morphology of trichomes and epicuticular waxes, a combination of FineFIX fixation and air drying is recommended.

Hybrid Solar Cells: Materials, Interfaces, and Devices

NASA Astrophysics Data System (ADS)

Mariani, Giacomo; Wang, Yue; Kaner, Richard B.; Huffaker, Diana L.

Photovoltaic technologies could play a pivotal role in tackling future fossil fuel energy shortages, while significantly reducing our carbon dioxide footprint. Crystalline silicon is pervasively used in single junction solar cells, taking up 80 % of the photovoltaic market. Semiconductor-based inorganic solar cells deliver relatively high conversion efficiencies at the price of high material and manufacturing costs. A great amount of research has been conducted to develop low-cost photovoltaic solutions by incorporating organic materials. Organic semiconductors are conjugated hydrocarbon-based materials that are advantageous because of their low material and processing costs and a nearly unlimited supply. Their mechanical flexibility and tunable electronic properties are among other attractions that their inorganic counterparts lack. Recently, collaborations in nanotechnology research have combined inorganic with organic semiconductors in a "hybrid" effort to provide high conversion efficiencies at low cost. Successful integration of these two classes of materials requires a profound understanding of the material properties and an exquisite control of the morphology, surface properties, ligands, and passivation techniques to ensure an optimal charge carrier generation across the hybrid device. In this chapter, we provide background information of this novel, emerging field, detailing the various approaches for obtaining inorganic nanostructures and organic polymers, introducing a multitude of methods for combining the two components to achieve the desired morphologies, and emphasizing the importance of surface manipulation. We highlight several studies that have fueled new directions for hybrid solar cell research, including approaches for maximizing efficiencies by controlling the morphologies of the inorganic component, and in situ molecular engineering via electrochemical polymerization of a polymer directly onto the inorganic nanowire surfaces. In the end, we provide some possible future directions for advancing the field, with a focus on flexible, lightweight, semitransparent, and low-cost photovoltaics.

Coevolution of bed surface patchiness and channel morphology: 1. Mechanisms of forced patch formation

USGS Publications Warehouse

Nelson, Peter A.; McDonald, Richard R.; Nelson, Jonathan M.; Dietrich, William E.

2015-01-01

Riverbeds frequently display a spatial structure where the sediment mixture composing the channel bed has been sorted into discrete patches of similar grain size. Even though patches are a fundamental feature in gravel bed rivers, we have little understanding of how patches form, evolve, and interact. Here we present a two-dimensional morphodynamic model that is used to examine in greater detail the mechanisms responsible for the development of forced bed surface patches and the coevolution of bed morphology and bed surface patchiness. The model computes the depth-averaged channel hydrodynamics, mixed-grain-size sediment transport, and bed evolution by coupling the river morphodynamic model Flow and Sediment Transport with Morphological Evolution of Channels (FaSTMECH) with a transport relation for gravel mixtures and the mixed-grain-size Exner equation using the active layer assumption. To test the model, we use it to simulate a flume experiment in which the bed developed a sequence of alternate bars and temporally and spatially persistent forced patches with a general pattern of coarse bar tops and fine pools. Cross-stream sediment flux causes sediment to be exported off of bars and imported into pools at a rate that balances downstream gradients in the streamwise sediment transport rate, allowing quasi-steady bar-pool topography to persist. The relative importance of lateral gravitational forces on the cross-stream component of sediment transport is a primary control on the amplitude of the bars. Because boundary shear stress declines as flow shoals over the bars, the lateral sediment transport is increasingly size selective and leads to the development of coarse bar tops and fine pools.

Effect of cetyl trimethyl ammonium bromide concentration on structure, morphology and carbon dioxide adsorption capacity of calcium hydroxide based sorbents

NASA Astrophysics Data System (ADS)

Hlaing, Nwe Ni; Vignesh, K.; Sreekantan, Srimala; Pung, Swee-Yong; Hinode, Hirofumi; Kurniawan, Winarto; Othman, Radzali; Thant, Aye Aye; Mohamed, Abdul Rahman; Salim, Chris

2016-02-01

Calcium hydroxide (Ca(OH)2) has been proposed as an important material for industrial, architectural, and environmental applications. In this study, calcium acetate was used as a precursor and cetyl trimethyl ammonium bromide (CTAB) was used as a surfactant to synthesize Ca(OH)2 based adsorbents for carbon dioxide (CO2) capture. The effect of CTAB concentration (0.2-0.8 M) on the structure, morphology and CO2 adsorption performance of Ca(OH)2 was studied in detail. The synthesized samples were characterized by X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy, field emission scanning electron microscopy (FESEM), BET surfaced area and thermogravimetry-differential thermal analysis (TG-DTA) techniques. The phase purity, crystallite size, Brunauer-Emmett-Teller (BET) surface area and CO2 adsorption performance of Ca(OH)2 precursor adsorbents were significantly increased when the concentration of CTAB was increased. XRD results showed that pure Ca(OH)2 phase was obtained at the CTAB concentration of 0.8 M. TGA results exhibited that 0.8 M of CTAB-assisted Ca(OH)2 precursor adsorbent possessed a residual carbonation conversion of ∼56% after 10 cycles.

Structural and electronic properties of low-index stoichiometric Cu2ZnSnS4 surfaces

NASA Astrophysics Data System (ADS)

Jia, Zhan-Ju; Wang, Yu-An; Zhao, Zong-Yan; Liu, Qing-Ju

2018-05-01

Over the past few years, quaternary Cu2ZnSnS4 (CZTS) has attracted a great deal of attention as the most promising photovoltaic absorber layer, due to its abundance and non-toxic properties. However, the significant surface structures and properties for photo-catalytic absorption layers have not yet been studied in detail for CZTS. Hence, the surface structure and electronic properties of low-index stoichiometric CZTS surfaces are calculated based on density functional theory. The relaxation is much large for the (001), (100), (101) and (112) surfaces. Moreover, more surface states appear at the bottom of conduction band and the top of valence band. The conduction band is mainly composed of S-3p and Sn-5p orbits. The valence band top is mainly composed of S-3p and Cu-3d orbits. The band gap values of five surfaces do not vary greatly. The dangling bond density for the (112) surfaces is minimal, resulting in minimum surface energy. Finally, the equilibrium morphology of CZTS is constructed by the Wulff rule. It is found that the {101} surface is the dominant surface (72.6%). These results will help us to better understand the surface properties of absorption layer that is related to CZTS surface and provide theoretical support for future experimental studies.

Engineering the performance of mixed matrix membranes for gas separations

NASA Astrophysics Data System (ADS)

Shu, Shu

Mixed matrix membranes that comprise domains of organic and inorganic components are investigated in this research. Such materials effectively circumvent the polymeric 'upper bound trade-off curve' and show properties highly attractive for industrial gas separations. Nevertheless, lack of intrinsic compatibility between the organic polymers and inorganic fillers poses the biggest challenge to successful fabrication of mixed matrix membranes. Consequently, control of the nanoscale interface between the sieve and polymer has been the key technical challenge to the implementation of composite membrane materials. The overarching goal of this research was to devise and explore approaches to enhance the performance of mixed matrix membranes by properly tailoring the sieve/polymer interface. In an effort to pursue the aforementioned objective, three approaches were developed and inspected: (i) use of silane coupling agents, (ii) hydrophobizing of sieve surface through alcohol etherification reactions, and (iii) a two-step modification sequence involving the use of a Grignard reagent. A comparison was drawn to evaluate these methodologies and the most effective strategy (Grignard treatment) was selected and further investigated. Successful formulation and characterization of mixed matrix membranes constituting zeolite 4A modified via the Grignard treatment are described in detail. Membranes with impressive improvements in gas separation efficiency and mechanical properties were demonstrated. The basis for the improvements in polymer/sieve compatibility enabled by this specific process were proposed and investigated. A key aspect of the present study was illuminating the detailed chemical mechanisms involved in the Grignard modification. Systematic characterization and carefully designed experiments revealed that the formation of distinctive surface structures is essentially a heterogeneous nucleation process, where Mg(OH)2 crystals grow from the nuclei previously extracted from zeolites. In addition to the main work, discovery of sonication-induced dealumination of zeolites was made during the systematic exploration of Grignard chemistry. The new procedure employing sonication can potentially be applied to prepare zeolites with a variety of Si/Al ratios under relatively mild conditions. The last part of this thesis focused on development of a technique to generalize the highly specific Grignard treatment to inorganic materials other than zeolite 4A. This work delivered composite membranes with improved interfacial adhesion. Moreover, research revealed the effect of surface nuclei density on the ultimate morphology of deposited nanostructures and how different surface morphologies influence polymer/filler interaction in composite membranes. Methods were devised to tailor the morphologies of such structures in order to optimize adhesion enhancement. The acquired results demonstrated the potential of extending this modification process to a broad domain of materials and render it a general methodology for interfacial adhesion promotion.

Interagency Report: Astrogeology 58, television cartography

USGS Publications Warehouse

Batson, Raymond M.

1973-01-01

The purpose of this paper is to illustrate the processing of digital television pictures into base maps. In this context, a base map is defined as a pictorial representation of planetary surface morphology accurately reproduced on standard map projections. Topographic contour lines, albedo or geologic overprints may be super imposed on these base maps. The compilation of geodetic map controls, the techniques of mosaic compilation, computer processing and airbrush enhancement, and the compilation of con tour lines are discussed elsewhere by the originators of these techniques. A bibliography of applicable literature is included for readers interested in more detailed discussions.

Lithium-Polymer battery based on polybithiophene as cathode material

NASA Astrophysics Data System (ADS)

Chen, J.; Wang, J.; Wang, C.; Too, C. O.; Wallace, G. G.

Stainless-steel mesh electrodes coated with polybithiophene, obtained by electrochemical polymerization (constant potential and constant current), have been investigated as cathode materials in a lithium-polybithiophene rechargeable battery by cyclic voltammetry, electrochemical impedance spectroscopy and long-term charge-discharge cycling process. The effects of different growth methods on the surface morphology of the films and the charge-discharge capacity are discussed in detail. The results show that polybithiophene-hexafluorophosphate is a very promising cathode material for manufacturing lithium-polymer rechargeable batteries with a highly stable discharge capacity of 81.67 mAh g -1 after 50 cycles.

Three-dimensional biofilm structure quantification.

PubMed

Beyenal, Haluk; Donovan, Conrad; Lewandowski, Zbigniew; Harkin, Gary

2004-12-01

Quantitative parameters describing biofilm physical structure have been extracted from three-dimensional confocal laser scanning microscopy images and used to compare biofilm structures, monitor biofilm development, and quantify environmental factors affecting biofilm structure. Researchers have previously used biovolume, volume to surface ratio, roughness coefficient, and mean and maximum thicknesses to compare biofilm structures. The selection of these parameters is dependent on the availability of software to perform calculations. We believe it is necessary to develop more comprehensive parameters to describe heterogeneous biofilm morphology in three dimensions. This research presents parameters describing three-dimensional biofilm heterogeneity, size, and morphology of biomass calculated from confocal laser scanning microscopy images. This study extends previous work which extracted quantitative parameters regarding morphological features from two-dimensional biofilm images to three-dimensional biofilm images. We describe two types of parameters: (1) textural parameters showing microscale heterogeneity of biofilms and (2) volumetric parameters describing size and morphology of biomass. The three-dimensional features presented are average (ADD) and maximum diffusion distances (MDD), fractal dimension, average run lengths (in X, Y and Z directions), aspect ratio, textural entropy, energy and homogeneity. We discuss the meaning of each parameter and present the calculations in detail. The developed algorithms, including automatic thresholding, are implemented in software as MATLAB programs which will be available at site prior to publication of the paper.

Morphological variation of dinoflagellate Prorocentrum lima (Ehrenberg) Dodge with geographical difference.

PubMed

Yoo, Jong Su

2004-01-01

Prorocentrum lima (Ehrenberg) Dodge, one of the cosmopolitan dinoflagellates, is basically benthic and is found on the surface of macroalgae and detritus. The identification of this species requires detailed morphological observation because of its close similarity to other benthic Prorocentrum species. The purpose of this study is to detect the morphological variability of P. lima using culture clones collected from several areas to find an adequate way of subdividing the species. In this study, 33 clones of P. lima were collected from Saipan, Tahiti, Indonesia, Japan and Bermuda, and their thecal valves and periflagellar area were observed by means of light microscopy with differential interference contrast optics and scanning electron microscopy. In general cells have two centrally located pyrenoids and a posterior nucleus. The surface of both valves has many valve pores except the center. Evenly spaced marginal pores are located along the edge of the valves. P. lima samples studied herein were subdivided into four major types (ellipsoidal, general, short, and elongate ovoid) according to their shapes, length-to-width ratio and number of valve pores. The length-to-width ratios of ellipsoidal, general, short, and elongate ovoid types were 1.32, 1.33-1.43, 1.20-1.27, and 1.53-1.60 microm respectively. Also there were slight differences in the number of valve pores. The number of valve pores examined in this study ranges from 40 to 97: ellipsoidal, general, and short ovoid types range from 40 to 91, while an elongate ovoid type ranges from 80 to 97. The combination of valve shape, number of valve pores and length-to-width ratio provides useful information on the morphological variation of P. lima.

[Corrosion resistant properties of different anodized microtopographies on titanium surfaces].

PubMed

Fangjun, Huo; Li, Xie; Xingye, Tong; Yueting, Wang; Weihua, Guo; Weidong, Tian

2015-12-01

To investigate the corrosion resistant properties of titanium samples prepared by anodic oxidation with different surface morphologies. Pure titanium substrates were treated by anodic oxidation to obtain porous titanium films in micron, submicron, and micron-submicron scales. The surface morphologies, coating cross-sectional morphologies, crystalline structures, and surface roughness of these samples were characterized. Electrochemical technique was used to measure the corrosion potential (Ecorr), current density of corrosion (Icorr), and polarization resistance (Rp) of these samples in a simulated body fluid. Pure titanium could be modified to exhibit different surface morphologies by the anodic oxidation technique. The Tafel curve results showed that the technique can improve the corrosion resistance of pure titanium. Furthermore, the corrosion resistance varied with different surface morphologies. The submicron porous surface sample demonstrated the best corrosion resistance, with maximal Ecorr and Rp and minimal Icorr. Anodic oxidation technology can improve the corrosion resistance of pure titanium in a simulated body fluid. The submicron porous surface sample exhibited the best corrosion resistance because of its small surface area and thick barrier layer.

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

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

[Macrocephalic spermatozoa. What would be the impact on reproduction?].

PubMed

Guichaoua, M-R; Mercier, G; Geoffroy-Siraudin, C; Paulmyer-Lacroix, O; Lanteaume, A; Metzler-Guillemin, C; Perrin, J; Achard, V

2009-09-01

We want to highlight the risk of infertility and failure of Assisted Reproductive Technologies due to the presence of macrocephalic spermatozoa (MS) in the sperm at rate equalling or superior to 20% in at least one semen analysis. We did a retrospective analysis of 19 infertile patients presenting MS at average rate between 14.3 and 49.7%. For each patient, at least one semen analysis showed a MS rate equal or superior to 20%. We did an automated analysis of the spermatozoa surface for 13 patients and a detailed analysis of the MS morphology in 18 patients. Thirteen couples benefited of one or more IVF with or without ICSI. The semen analysis shows an impairment of one or more parameter of the sperm in all patients. Three morphological aspects for MS were highlighted: MS with irregular head, MS with regular head, and MS with multiple heads, with a dominance of irregular heads. The spermatozoa surface analysis shows a significant increase of the average surface and of the standard deviation (p<0.0001). The average rate of pregnancies by transfer is decreased compared to usual rates in our laboratories (13% versus 28%). We want to sensitize biologist and clinical doctors to the existence of partial forms of this syndrome, which could be related to infertility with impaired sperm parameters and low pregnancy rates after FIV or ICSI.

Manus track preservation bias as a key factor for assessing trackmaker identity and quadrupedalism in basal ornithopods.

PubMed

Castanera, Diego; Vila, Bernat; Razzolini, Novella L; Falkingham, Peter L; Canudo, José I; Manning, Phillip L; Galobart, Angel

2013-01-01

The Las Cerradicas site (Tithonian-Berriasian), Teruel, Spain, preserves at least seventeen dinosaur trackways, some of them formerly attributed to quadrupedal ornithopods, sauropods and theropods. The exposure of new track evidence allows a more detailed interpretation of the controversial tridactyl trackways as well as the modes of locomotion and taxonomic affinities of the trackmakers. Detailed stratigraphic analysis reveals four different levels where footprints have been preserved in different modes. Within the tridactyl trackways, manus tracks are mainly present in a specific horizon relative to surface tracks. The presence of manus tracks is interpreted as evidence of an ornithopod trackmaker. Cross-sections produced from photogrammetric digital models show different depths of the pes and manus, suggesting covariance in loading between the forelimbs and the hindlimbs. Several features (digital pads, length/width ratio, claw marks) of some ornithopod pes tracks from Las Cerradicas are reminiscent of theropod pedal morphology. This morphological convergence, combined with the shallow nature of the manus tracks, which reduces preservation potential, opens a new window into the interpretation of these tridactyl tracks. Thus, trackmaker assignations during the Jurassic-Cretaceous interval of purported theropod trackways may potentially represent ornithopods. Moreover, the Las Cerradicas trackways are further evidence for quadrupedalism among some basal small- to medium-sized ornithopods from this time interval.

Numerical Simulations of Supernova Remnant Evolution in a Cloudy Interstellar Medium

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

Slavin, Jonathan D.; Smith, Randall K.; Foster, Adam

The mixed morphology class of supernova remnants has centrally peaked X-ray emission along with a shell-like morphology in radio emission. White and Long proposed that these remnants are evolving in a cloudy medium wherein the clouds are evaporated via thermal conduction once being overrun by the expanding shock. Their analytical model made detailed predictions regarding temperature, density, and emission profiles as well as shock evolution. We present numerical hydrodynamical models in 2D and 3D including thermal conduction, testing the White and Long model and presenting results for the evolution and emission from remnants evolving in a cloudy medium. We findmore » that, while certain general results of the White and Long model hold, such as the way the remnants expand and the flattening of the X-ray surface brightness distribution, in detail there are substantial differences. In particular we find that the X-ray luminosity is dominated by emission from shocked cloud gas early on, leading to a bright peak, which then declines and flattens as evaporation becomes more important. In addition, the effects of thermal conduction on the intercloud gas, which is not included in the White and Long model, are important and lead to further flattening of the X-ray brightness profile as well as lower X-ray emission temperatures.« less

Geologic Maps of the Dardanus Sulcus (Jg-6), Misharu (Jg-10), Nabu (Jg-11), and Namtar (Jg-14) Quadrangles of Ganymede

USGS Publications Warehouse

Maxwell, Ted A.; Marvin, Ursula B.

2001-01-01

Ganymede is the largest (~5,200 km diameter) of the Jovian satellites. Surficial features on Ganymede, as recorded by the Voyager 1 and 2 spacecraft (Smith and others, 1979a; 1979b), indicate a complex history of crustal formation. Several episodes of crustal modification led to the formation of curvilinear systems of furrows in dark terrain, the emplacement of light materials, and the creation of grooves in light terrain. Prior to exploration of the Jovian system by spacecraft, Earth-based observations established that the surface of Ganymede is dominated by water ice with various admixtures of fine silicate (rock) material (Pilcher and others, 1972; Sill and Clark, 1982). No agreement yet exists as to the amount of water in the near surface material; early estimates based on spectral reflectance data suggested that half the surface was covered by nearly pure water ice, whereas later studies by Clark (1981) indicated that up to 95% of the surface could be water ice and still be consistent with spectroscopic data. The Pioneer encounters with the Jovian system in 1973 and 1974 confirmed that Ganymede was made up of patches of light and dark terrain but did not have the spatial resolution needed to determine the percent cover of water ice, or geologic relations of surface materials. Not until the Voyager encounters was the surface seen with sufficient detail to enable geologic mapping. On the basis of albedo contrasts, surface morphology, crater density, and superposition relations, geologic mapping was done using principles and techniques that have been applied to the Earth, Moon, and other terrestrial planets (Wilhelms, 1972). Considerable uncertainty exists in applying such methods to bodies having icy crusts, as the internal processes that produce their surface configurations are poorly understood, and the resolution of the Voyager images is barely sufficient to show the detail required to interpret structural and stratigraphic relations. With the exception of the extreme southeastern portion of the Namtar quadrangle (Jg- 14), all images used for mapping were taken by Voyager 1. At the time of encounter, the eastern portion of the Misharu (Jg–10) and Namtar quadrangles were near the terminator, making it difficult to distinguish albedo variations best seen at high sun angles. The western quadrangles were imaged at resolutions of 2–5 km/pixel (Batson and others, 1980) from an oblique angle, so albedo variations can be seen, but topography and morphology are not well expressed in the images.

Quantifying temporal bone morphology of great apes and humans: an approach using geometric morphometrics

PubMed Central

Lockwood, Charles A; Lynch, John M; Kimbel, William H

2002-01-01

The hominid temporal bone offers a complex array of morphology that is linked to several different functional systems. Its frequent preservation in the fossil record gives the temporal bone added significance in the study of human evolution, but its morphology has proven difficult to quantify. In this study we use techniques of 3D geometric morphometrics to quantify differences among humans and great apes and discuss the results in a phylogenetic context. Twenty-three landmarks on the ectocranial surface of the temporal bone provide a high level of anatomical detail. Generalized Procrustes analysis (GPA) is used to register (adjust for position, orientation and scale) landmark data from 405 adults representing Homo, Pan, Gorilla and Pongo. Principal components analysis of residuals from the GPA shows that the major source of variation is between humans and apes. Human characteristics such as a coronally orientated petrous axis, a deep mandibular fossa, a projecting mastoid process, and reduced lateral extension of the tympanic element strongly impact the analysis. In phenetic cluster analyses, gorillas and orangutans group together with respect to chimpanzees, and all apes group together with respect to humans. Thus, the analysis contradicts depictions of African apes as a single morphotype. Gorillas and orangutans lack the extensive preglenoid surface of chimpanzees, and their mastoid processes are less medially inflected. These and other characters shared by gorillas and orangutans are probably primitive for the African hominid clade. PMID:12489757

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.

An Optimal Strategy for Accurate Bulge-to-disk Decomposition of Disk Galaxies

NASA Astrophysics Data System (ADS)

Gao, Hua; Ho, Luis C.

2017-08-01

The development of two-dimensional (2D) bulge-to-disk decomposition techniques has shown their advantages over traditional one-dimensional (1D) techniques, especially for galaxies with non-axisymmetric features. However, the full potential of 2D techniques has yet to be fully exploited. Secondary morphological features in nearby disk galaxies, such as bars, lenses, rings, disk breaks, and spiral arms, are seldom accounted for in 2D image decompositions, even though some image-fitting codes, such as GALFIT, are capable of handling them. We present detailed, 2D multi-model and multi-component decomposition of high-quality R-band images of a representative sample of nearby disk galaxies selected from the Carnegie-Irvine Galaxy Survey, using the latest version of GALFIT. The sample consists of five barred and five unbarred galaxies, spanning Hubble types from S0 to Sc. Traditional 1D decomposition is also presented for comparison. In detailed case studies of the 10 galaxies, we successfully model the secondary morphological features. Through a comparison of best-fit parameters obtained from different input surface brightness models, we identify morphological features that significantly impact bulge measurements. We show that nuclear and inner lenses/rings and disk breaks must be properly taken into account to obtain accurate bulge parameters, whereas outer lenses/rings and spiral arms have a negligible effect. We provide an optimal strategy to measure bulge parameters of typical disk galaxies, as well as prescriptions to estimate realistic uncertainties of them, which will benefit subsequent decomposition of a larger galaxy sample.

Mapping the Juan Fernandez Ridge (Pacific SW): geomorphogy for understanding volcanic evolution and environmental protection

NASA Astrophysics Data System (ADS)

Lara, L.; Diaz-Naveas, J.

2016-02-01

As most of the oceans worldwide, bathymetry of the Juan Fernandez Ridge (JFR) and surrounding seafloor in the Pacific SW is scarce and still deserves more efforts. Recent advances with new the AGS61 Cabo de Hornos vessel, equipped with a high resolution multibeam ecosounder allows to recognize with unprecedented detail some volcano morphologies. Main motivation for this recent survey was environmental protection of fisheries and endemic fauna, but it is also related with ongoing research about the evolution of the JFR and the competing roles played by mantle and tectonic processes. Here we describe some relevant features as a post-erosional stage at O'Higgins seamount, the oldest ca. 9 Ma component of the ridge that correspond to a paired structure, represented by a radial array of flank cones. .The large edifice has a flat surface at ca. 700 mbsl typical of guyots with also radial rift zones and is connected by a saddle with the smaller eastern seamount. On the western segment, contrasting morphology of JF5 West (Cinque Ports) and JF5 East (Duke) poses a doubt about the age progression along the chain. In fact, Duke is a perfect stellar highly eroded seamount with four rift zones while Cinque Ports is a guyot with post-erosional flank cones. Thus, detailed morphology based on bathymetry and backscatter signal is going to be used for both Earth science research and environmental issues, along with some efforts aimed to establish the extension of the continental shelf beyond the 200 miles.

Infrared image enhancement based on the edge detection and mathematical morphology

NASA Astrophysics Data System (ADS)

Zhang, Linlin; Zhao, Yuejin; Dong, Liquan; Liu, Xiaohua; Yu, Xiaomei; Hui, Mei; Chu, Xuhong; Gong, Cheng

2010-11-01

The development of the un-cooled infrared imaging technology from military necessity. At present, It is widely applied in industrial, medicine, scientific and technological research and so on. The infrared radiation temperature distribution of the measured object's surface can be observed visually. The collection of infrared images from our laboratory has following characteristics: Strong spatial correlation, Low contrast , Poor visual effect; Without color or shadows because of gray image , and has low resolution; Low definition compare to the visible light image; Many kinds of noise are brought by the random disturbances of the external environment. Digital image processing are widely applied in many areas, it can now be studied up close and in detail in many research field. It has become one kind of important means of the human visual continuation. Traditional methods for image enhancement cannot capture the geometric information of images and tend to amplify noise. In order to remove noise and improve visual effect. Meanwhile, To overcome the above enhancement issues. The mathematical model of FPA unit was constructed based on matrix transformation theory. According to characteristics of FPA, Image enhancement algorithm which combined with mathematical morphology and edge detection are established. First of all, Image profile is obtained by using the edge detection combine with mathematical morphological operators. And then, through filling the template profile by original image to get the ideal background image, The image noise can be removed on the base of the above method. The experiments show that utilizing the proposed algorithm can enhance image detail and the signal to noise ratio.

An Optimal Strategy for Accurate Bulge-to-disk Decomposition of Disk Galaxies

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

Gao Hua; Ho, Luis C.

The development of two-dimensional (2D) bulge-to-disk decomposition techniques has shown their advantages over traditional one-dimensional (1D) techniques, especially for galaxies with non-axisymmetric features. However, the full potential of 2D techniques has yet to be fully exploited. Secondary morphological features in nearby disk galaxies, such as bars, lenses, rings, disk breaks, and spiral arms, are seldom accounted for in 2D image decompositions, even though some image-fitting codes, such as GALFIT, are capable of handling them. We present detailed, 2D multi-model and multi-component decomposition of high-quality R -band images of a representative sample of nearby disk galaxies selected from the Carnegie-Irvine Galaxymore » Survey, using the latest version of GALFIT. The sample consists of five barred and five unbarred galaxies, spanning Hubble types from S0 to Sc. Traditional 1D decomposition is also presented for comparison. In detailed case studies of the 10 galaxies, we successfully model the secondary morphological features. Through a comparison of best-fit parameters obtained from different input surface brightness models, we identify morphological features that significantly impact bulge measurements. We show that nuclear and inner lenses/rings and disk breaks must be properly taken into account to obtain accurate bulge parameters, whereas outer lenses/rings and spiral arms have a negligible effect. We provide an optimal strategy to measure bulge parameters of typical disk galaxies, as well as prescriptions to estimate realistic uncertainties of them, which will benefit subsequent decomposition of a larger galaxy sample.« less

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.

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.

Simulations of molecular self-assembled monolayers on surfaces: packing structures, formation processes and functions tuned by intermolecular and interfacial interactions.

PubMed

Wen, Jin; Li, Wei; Chen, Shuang; Ma, Jing

2016-08-17

Surfaces modified with a functional molecular monolayer are essential for the fabrication of nano-scale electronics or machines with novel physical, chemical, and/or biological properties. Theoretical simulation based on advanced quantum chemical and classical models is at present a necessary tool in the development, design, and understanding of the interfacial nanostructure. The nanoscale surface morphology, growth processes, and functions are controlled by not only the electronic structures (molecular energy levels, dipole moments, polarizabilities, and optical properties) of building units but also the subtle balance between intermolecular and interfacial interactions. The switchable surfaces are also constructed by introducing stimuli-responsive units like azobenzene derivatives. To bridge the gap between experiments and theoretical models, opportunities and challenges for future development of modelling of ferroelectricity, entropy, and chemical reactions of surface-supported monolayers are also addressed. Theoretical simulations will allow us to obtain important and detailed information about the structure and dynamics of monolayer modified interfaces, which will guide the rational design and optimization of dynamic interfaces to meet challenges of controlling optical, electrical, and biological functions.

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.

Predictive model for ice formation on superhydrophobic surfaces.

PubMed

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

2011-12-06

The prevention and control of ice accumulation has important applications in aviation, building construction, and energy conversion devices. One area of active research concerns the use of superhydrophobic surfaces for preventing ice formation. The present work develops a physics-based modeling framework to predict ice formation on cooled superhydrophobic surfaces resulting from the impact of supercooled water droplets. This modeling approach analyzes the multiple phenomena influencing ice formation on superhydrophobic surfaces through the development of submodels describing droplet impact dynamics, heat transfer, and heterogeneous ice nucleation. These models are then integrated together to achieve a comprehensive understanding of ice formation upon impact of liquid droplets at freezing conditions. The accuracy of this model is validated by its successful prediction of the experimental findings that demonstrate that superhydrophobic surfaces can fully prevent the freezing of impacting water droplets down to surface temperatures of as low as -20 to -25 °C. The model can be used to study the influence of surface morphology, surface chemistry, and fluid and thermal properties on dynamic ice formation and identify parameters critical to achieving icephobic surfaces. The framework of the present work is the first detailed modeling tool developed for the design and analysis of surfaces for various ice prevention/reduction strategies. © 2011 American Chemical Society

Bayes Forest: a data-intensive generator of morphological tree clones

PubMed Central

Järvenpää, Marko; Åkerblom, Markku; Raumonen, Pasi; Kaasalainen, Mikko

2017-01-01

Abstract Detailed and realistic tree form generators have numerous applications in ecology and forestry. For example, the varying morphology of trees contributes differently to formation of landscapes, natural habitats of species, and eco-physiological characteristics of the biosphere. Here, we present an algorithm for generating morphological tree “clones” based on the detailed reconstruction of the laser scanning data, statistical measure of similarity, and a plant growth model with simple stochastic rules. The algorithm is designed to produce tree forms, i.e., morphological clones, similar (and not identical) in respect to tree-level structure, but varying in fine-scale structural detail. Although we opted for certain choices in our algorithm, individual parts may vary depending on the application, making it a general adaptable pipeline. Namely, we showed that a specific multipurpose procedural stochastic growth model can be algorithmically adjusted to produce the morphological clones replicated from the target experimentally measured tree. For this, we developed a statistical measure of similarity (structural distance) between any given pair of trees, which allows for the comprehensive comparing of the tree morphologies by means of empirical distributions describing the geometrical and topological features of a tree. Finally, we developed a programmable interface to manipulate data required by the algorithm. Our algorithm can be used in a variety of applications for exploration of the morphological potential of the growth models (both theoretical and experimental), arising in all sectors of plant science research. PMID:29020742

Forensic analysis of rockfall scars

NASA Astrophysics Data System (ADS)

de Vilder, Saskia J.; Rosser, Nick J.; Brain, Matthew J.

2017-10-01

We characterise and analyse the detachment (scar) surfaces of rockfalls to understand the mechanisms that underpin their failure. Rockfall scars are variously weathered and comprised of both discontinuity release surfaces and surfaces indicative of fracturing through zones of previously intact rock, known as rock bridges. The presence of rock bridges and pre-existing discontinuities is challenging to quantify due to the difficulty in determining discontinuity persistence below the surface of a rock slope. Rock bridges form an important control in holding blocks onto rockslopes, with their frequency, extent and location commonly modelled from the surface exposure of daylighting discontinuities. We explore an alternative approach to assessing their role, by characterising failure scars. We analyse a database of multiple rockfall scar surfaces detailing the areal extent, shape, and location of broken rock bridges and weathered surfaces. Terrestrial laser scanning and gigapixel imagery were combined to record the detailed texture and surface morphology. From this, scar surfaces were mapped via automated classification based on RGB pixel values. Our analysis of the resulting data from scars on the North Yorkshire coast (UK) indicates a wide variation in both weathering and rock bridge properties, controlled by lithology and associated rock mass structure. Importantly, the proportion of rock bridges in a rockfall failure surface does not increase with failure size. Rather larger failures display fracturing through multiple rock bridges, and in contrast smaller failures fracture occurs only through a single critical rock bridge. This holds implications for how failure mechanisms change with rockfall size and shape. Additionally, the location of rock bridges with respect to the geometry of an incipient rockfall is shown to determine failure mode. Weathering can occur both along discontinuity surfaces and previously broken rock bridges, indicating the sequential stages of progressively detaching rockfall. Our findings have wider implications for hazard assessment where rock slope stability is dependent on the nature of rock bridges, how this is accounted for in slope stability modelling, and the implications of rock bridges on long-term rock slope evolution.

The Relationship Between Sediment Properties and Sedimentation Patterns on a Macrotidal Gravel Beach over a Semi-lunar Tidal Cycle.

NASA Astrophysics Data System (ADS)

Buscombe, D.; Masselink, G.

2007-12-01

Detailed measurements of profile and sediment dynamics have been obtained from a macrotidal gravel barrier beach in southern England. Surface and sub-surface sediment samples, beach profiles, and disturbance depths were taken from the intertidal zone on consecutive low tides over semi-lunar tidal cycles, along with continuous wave and tide measurements. Results from two separate field surveys are presented, representing 26 and 24 consecutive low tides, respectively. A combination of Canonical Correlation Analysis (CCA) and Empirical Orthogonal Function (EOF) analysis was used to identify a number of consistent relationships in morphological and sedimentological variables not readily apparent using ordinary correlations. The disadvantage of such statistical models is that the relationships obtained cannot be expressed in physically meaningful units, which does limit its utility in physical-numerical modelling. However, the results reveal some interesting relationships between gravel beachface sedimentology and morphological change. For example, beachface morphology and sedimentology are more similar at a given spatial location over time than over space (cross-shore) at any individual time. Subsurface sedimentology over the depth of disturbance indicates that the beach step can be traced through the sediment characteristics. Indeed, the study suggests that gravel beachface sedimentology is 'slaved' to morphological change rather than vice-versa; and that the relationship becomes more evident as secondary morphological features develop on the beachface. The results imply that median sediment size and geometric sorting are suitable parameters for detecting such relationships. Strong hysteresis over space was present in the EOF modes associated with the most variance in the data sets, for both sediment size and sorting. Statistically significant relationships were found between the temporal modes of (absolute) size/sorting and net sedimentation associated with the largest variance in the non-decomposed respective data sets. Finally, significant relationships were found between a suite of measured hydrodynamic time-series and pairs of significantly correlated morpho-sedimentary eigenmodes. The techniques used were thus able to objectively demonstrate linear association between morphological and sedimentological change on a gravel beachface over a semi-lunar tidal cycle; and also that simultaneous changes in each could be linearly correlated to hydrodynamic forcing.

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.

Morphology-Patterned Anisotropic Wetting Surface for Fluid Control and Gas-Liquid Separation in Microfluidics.

PubMed

Wang, Shuli; Yu, Nianzuo; Wang, Tieqiang; Ge, Peng; Ye, Shunsheng; Xue, Peihong; Liu, Wendong; Shen, Huaizhong; Zhang, Junhu; Yang, Bai

2016-05-25

This article shows morphology-patterned stripes as a new platform for directing flow guidance of the fluid in microfluidic devices. Anisotropic (even unidirectional) spreading behavior due to anisotropic wetting of the underlying surface is observed after integrating morphology-patterned stripes with a Y-shaped microchannel. The anisotropic wetting flow of the fluid is influenced by the applied pressure, dimensions of the patterns, including the period and depth of the structure, and size of the channels. Fluids with different surface tensions show different flowing anisotropy in our microdevice. Moreover, the morphology-patterned surfaces could be used as a microvalve, and gas-water separation in the microchannel was realized using the unidirectional flow of water. Therefore, benefiting from their good performance and simple fabrication process, morphology-patterned surfaces are good candidates to be applied in controlling the fluid behavior in microfluidics.

Dynamics and internal structure of an Alaskan debris-covered glacier from repeat airborne photogrammetry and surface geophysics

NASA Astrophysics Data System (ADS)

Holt, John; Levy, Joseph; Petersen, Eric; Larsen, Chris; Fahnestock, Mark

2016-04-01

Debris-covered glaciers and rock glaciers encompass a range of compositions and activity, and can be useful paleoclimate indicators. They also respond differently to ongoing climate change than glaciers without a protective cover. Their flow dynamics are not well understood, and their unique surface morphologies, including lobate fronts and arcuate ridges, likely result from viscous flow influenced by a combination of composition, structure, and climatic factors. However, basic connections between flow kinematics and surface morphology have not yet been established, limiting our ability to understand these features. In order to begin to address this problem we have undertaken airborne and surface studies of multiple debris-covered glaciers in Alaska and the western U.S. Sourdough Rock Glacier in the St. Elias Mountains, Alaska, is completely debris-covered and exhibits numerous transverse compressional ridges. Its trunk also exhibits highly regular bumps and swales with a wavelength of ~175 m and amplitudes up to 12 m. In the middle trunk, lineations (boulder trains and furrows) bend around a point roughly 200m from the eastern edge. We acquired five high-resolution airborne surveys of Sourdough Rock Glacier between late 2013 and late 2015 using lidar and photogrammetry to assess annual and seasonal change at the sub-meter level. Differencing the DTMs provides vertical change while feature tracking in orthophotos provide horizontal velocities that indicate meters of annual motion. The flow field is highly correlated with surface features; in particular, compressional ridges in the lower lobe. Stranded, formerly active lobes are also apparent. Surface geophysical studies were undertaken to constrain internal structure and composition using a combination of ground-penetrating radar (GPR) at 50 and 100 MHz in six transects, and time-domain electromagnetic (TDEM) measurements at 47 locations, primarily in an along-flow transect and two cross-flow transects. We infer from the GPR and TDEM data that Sourdough Rock Glacier is 40-50 m thick and consists of a core of relatively pure glacier ice preserved under a 2.5-3 m thick debris mantle. In conclusion, Sourdough is actively flowing, with surface velocities that correlate with surface slope and thickness. A bedrock restriction is inferred from bending flow lines, low surface velocities, and localized thinning of the ice. This comprehensive suite of observations provides the potential to model ice flow and to ultimately link details of the surface morphology to accumulation and rheology through flow kinematics and internal structure.

Emplacement of Pahoehoe Toe Networks: Observations of May, 2010 Tube-fed Flows at Kilauea Volcano, Hawai'i

NASA Astrophysics Data System (ADS)

Crown, D. A.; Ramsey, M.; Hon, K.

2010-12-01

Pahoehoe lava flows are compound features that consist of multiple overlapping and interfingering lobes and exhibit morphologically diverse surfaces characterized by channelized zones, smooth-surfaced sheets, and numerous, small toe networks. Previous work compiled detailed planform maps of solidified pahoehoe toe networks to document their morphology, morphometry and connective relationships in order to provide constraints on lava transport models. In order to expand this research to active flow emplacement, we observed slow-moving, tube-fed pahoehoe flows on the coastal plain near Kalapana, Hawaii in May, 2010. The evolution of pahoehoe toe and toe network characteristics over their emplacement history was examined and the role of small-scale flow inflation on the advance of pahoehoe lobes evaluated. We collected both visible video footage and high-speed, high-precision thermal infrared (TIR) data using a FLIR S-40 camera. The TIR data provide surface temperature maps that can be easily used to identify formation of new toes and track their growth and surface cooling. From these maps, lobe development, connective relationships, and frontal and lateral spreading rates can be analyzed. Preliminary results suggest that regular cycles of activity characterize the development of these pahoehoe lobes: 1) emplacement of new toes in local topographic lows at the front, margin, and within the interior of an active lobe forming small interconnected networks, 2) decline and sometimes temporary cessation in the production of new pahoehoe toes, 3) inflation of the recently emplaced flow surface, either partially or en masse depending on the rate of influx of new lava, the degree of irregularity of the pre-flow surface, and/or the slope across the recently emplaced lava surface, and 4) fracturing of the recently emplaced surface crust that feeds emplacement of new toes. Inflation fractures typically cut across several previously emplaced toes and can occur at the front, along the margins, or within the active lobe, even at significant distances behind the flow front.

Anatomical Details of the Rabbit Nasal Passages and Their Implications in Breathing, Air Conditioning, and Olfaction

PubMed Central

Si, Xiuhua April; Kim, JongWon; Zhang, Yu; Jacob, Richard E.; Kabilan, Senthil; Corley, Richard A.

2016-01-01

The rabbit is commonly used as a laboratory animal for inhalation toxicology tests and detail knowledge of the rabbit airway morphometry is needed for outcome analysis or theoretical modeling. The objective of this study is to quantify the morphometric dimension of the nasal airway of a New Zealand white rabbit and to relate the morphology and functions through analytical and computational methods. Images of high-resolution MRI scans of the rabbit were processed to measure the axial distribution of the cross-sectional areas, perimeter, and complexity level. The lateral recess, which has functions other than respiration or olfaction, was isolated from the nasal airway and its dimension was quantified separately. A low Reynolds number turbulence model was implemented to simulate the airflow, heat transfer, vapor transport, and wall shear stress. Results of this study provide detailed morphological information of the rabbit that can be used in the studies of olfaction, inhalation toxicology, drug delivery, and physiology-based pharmacokinetics modeling. For the first time, we reported a spiral nasal vestibule that splits into three paths leading to the dorsal meatus, maxilloturbinate, and ventral meatus, respectively. Both non-dimensional functional analysis and CFD simulations suggested that the airflow in the rabbit nose is laminar and the unsteady effect is only significantly during sniffing. Due to the large surface-to-volume ratio, the maxilloturbinate is highly effective in warming and moistening the inhaled air to body conditions. The unique anatomical structure and respiratory airflow pattern may have important implications for designing new odorant detectors or electronic noses. PMID:27145450

High morphological plasticity and global geographical distribution of the Pacific broad tapeworm Adenocephalus pacificus (syn. Diphyllobothrium pacificum): molecular and morphological survey.

PubMed

Hernández-Orts, Jesús Servando; Scholz, Tomáš; Brabec, Jan; Kuzmina, Tetiana; Kuchta, Roman

2015-09-01

The most important causative agent of human diphyllobothriosis in South America, Diphyllobothrium pacificum, is transferred to the original genus Adenocephalus Nybelin, 1931; revised and redescribed on the basis of the evaluation of an extensive material collected mainly from northern fur seal, Callorhinus ursinus, from St. Paul Island, Alaska. Detailed analysis of morphological and morphometrical data shows a high variability in most of the characteristics traditionally used in diagnosis of diphyllobothriid tapeworms. Phylogenetic analyses based on newly characterised sequences of mitochondrial cytochrome c oxidase subunit 1 and nuclear large subunit ribosomal RNA genes consistently reveal Adenocephalus pacificus as a sister lineage to the clade formed of the remaining Diphyllobothrium species and other genera (Digramma, Diplogonoporus, Ligula). Despite the generally similar morphology, A. pacificus can be differentiated from the closely related taxa in the presence of transverse papilla-like tegumental protuberances distributed anteriorly, separated by narrow semicircular grooves on the ventral surface of proglottids between their anterior margin and the anterior edge of the male gonopore, and relatively small eggs. A. pacificus displays a relatively low host specificity (found in 9 of 16 otariids, and in accidental hosts such as man, dog and jackal, the latter representing a new host) and a uniquely wide geographical distribution on both hemispheres. In addition, suitability of morphological criteria used in diagnostics of diphyllobothriid cestodes is discussed. Copyright © 2015 Elsevier B.V. All rights reserved.

Passage-dependent morphological and phenotypical changes of a canine histiocytic sarcoma cell line (DH82 cells).

PubMed

Heinrich, Franziska; Contioso, Vanessa Bono; Stein, Veronika M; Carlson, Regina; Tipold, Andrea; Ulrich, Reiner; Puff, Christina; Baumgärtner, Wolfgang; Spitzbarth, Ingo

2015-01-15

DH82 cells represent a permanent macrophage cell line isolated from a dog with histiocytic sarcoma (HS) and are commonly used in various fields of research upon infection and cancer, respectively. Despite its frequent use, data on cell surface antigen expression of this cell line are fragmentary and in part inconsistent. We therefore aimed at a detailed morphological and antigenic characterization of DH82 cells with respect to passage-dependent differences. Cellular morphology of early (≤ 13) and late (≥ 66) passages of DH82 cells was evaluated via scanning electron microscopy. Moreover, cells were labelled with 10 monoclonal antibodies directed against CD11c, CD14, CD18, CD44, CD45, CD80, CD86, MHC-I, MHC-II, and ICAM-1 for flow cytometric analysis. Early passage cells were characterized by round cell bodies with abundant small cytoplasmic projections whereas later passages exhibited a spindle-shaped morphology with large processes. The percentage of CD11c-, CD14-, CD18-, CD45-, and CD80 positive cells significantly decreased in late passages whereas the expression of CD44, CD86, MHC-I, MHC-II and ICAM-1 remained unchanged. DH82 cells represent a remarkably heterogeneous cell line with divergent antigenic and morphologic properties. The present findings have important implications for future studies, which should consider distinct characteristics with regard to the used passage. Copyright © 2014 Elsevier B.V. All rights reserved.

Morphologic and thermophysical characteristics of lava flows southwest of Arsia Mons, Mars

NASA Astrophysics Data System (ADS)

Crown, David A.; Ramsey, Michael S.

2017-08-01

The morphologic and thermophysical characteristics of part of the extensive lava flow fields southwest of Arsia Mons (22.5-27.5°S, 120-130°W) have been examined using a combination of orbital VNIR and TIR datasets. THEMIS images provide context for the regional geology and record diurnal temperature variability that is diverse and unusual for flow surfaces in such close proximity. CTX images were used to distinguish dominant flow types and assess local age relationships between individual lava flows. CTX and HiRISE images provide detailed information on flow surface textures and document aeolian effects as they reveal fine-grained deposits in many low-lying areas of the flow surfaces as well as small patches of transverse aeolian ridges. Although this region is generally dust-covered and has a lower overall thermal inertia, the THEMIS data indicate subtle spectral variations within the population of lava flows studied. These variations could be due to compositional differences among the flows or related to mixing of flow and aeolian materials. Specific results regarding flow morphology include: a) Two main lava flow types (bright, rugged and dark, smooth as observed in CTX images) dominate the southwest Arsia Mons/NE Daedalia Planum region; b) the bright, rugged flows have knobby, ridged, and/or platy surface textures, commonly have medial channel/levee systems, and may have broad distal lobes; c) the dark, smooth flows extend from distributary systems that consist of combinations of lava channels, lava tubes, and/or sinuous ridges and plateaus; and d) steep-sided, terraced margins, digitate breakout lobes, and smooth-surfaced plateaus along lava channel/tube systems are interpreted as signatures of flow inflation within the dark, smooth flow type. These flows exhibit smoother upper surfaces, are thinner, and have more numerous, smaller lobes, which, along with their the channel-/tube-fed nature, indicate a lower viscosity lava than for the bright, rugged flows. Flow patterns and local interfingering and overlapping relationships are delineated in CTX images and allow reconstruction of the complex flow field surfaces. Darker channel-/tube-fed flows are generally younger than adjacent thicker, bright, rugged flows; however, the diversity and complexity of temporal relationships observed, along with the thermophysical variability, suggests that lava sources with different eruptive styles and magnitudes and/or lavas that experienced different local emplacement conditions were active contemporaneously.

Effect of Ambient Temperature on Hydrophobic Recovery Behavior of Silicone Rubber Composites

NASA Astrophysics Data System (ADS)

Peng, Xiangyang; Li, Zijian; Zheng, Feng; Zhang, Ni; Huang, Zhen; Fang, Pengfei

A series of silicone rubber samples with different cyclosiloxanes contents have been successfully prepared, and their hydrophobic recovery behaviors and mechanism were investigated in detail. The gas chromatography-mass spectroscopy technique after Soxhlet extraction was utilized to examine the low molecular weight siloxanes in the sample, SEM was used to observe the surface morphology of the silicone rubber influenced by plasma treatment, and contact angle measurement was applied to probe the hydrophobic recovery of the sample surface after plasma treatment at different storage temperatures. The storage time-dependent contact angle of water can be well fitted by the diffusion model calculated from Fick’s second law. The results imply that the hydrophobic recovery of silicone rubber is related to the diffusion of low molecular weight siloxanes, while larger content or higher temperature can induce faster hydrophobic recovery.

A revision of the Neotropical tortoise beetle genus Eurypedus Gistel 1834 (Coleoptera: Chrysomelidae).

PubMed

Shin, Chulwoo

2016-09-06

The genus Eurypedus Gistel is revised based on detailed morphological study, including examination of the mouthparts and genitalia. Besides previously known diagnostic characters, such as an oblong and laterally parallel-sided body, narrow elytral lamella, narrow prosternal process between the procoxae, and angled pronotal base, new diagnostic characters are identified: antennal notches on the ventral surface of antennomeres V-XI, a stridulatory file on the vertex, and paired projections on the ventral surface of the pronotum. The distinct stridulatory file is found only in males. The number of ridges of the stridulatory file varies between 48 and 59. Eurypedus thoni Barber (= Cassida oblonga Sturm in Thon) syn. nov. is synonymized with E. peltoides (Boheman). The remaining two species E. peltoides and E. nigrosignatus (Boheman) show distinct distributions separated by the Amazon Basin.

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.

Novel method for controllable fabrication of a superhydrophobic CuO surface on AZ91D magnesium alloy.

PubMed

She, Zuxin; Li, Qing; Wang, Zhongwei; Li, Longqin; Chen, Funan; Zhou, Juncen

2012-08-01

A novel method for controllable fabrication of a superhydrophobic CuO surface on AZ91D magnesium alloy is reported in this paper. Hierarchical structure composed of micro/nano-featherlike CuO was obtained by electrodeposition of Cu-Zn alloy coating and subsequently an electrochemical anodic treatment in alkaline solution. After modification with lauric acid, the surface became hydrophobicity/superhydrophobicity. The formation of featherlike CuO structures was controllable by varying the coating composition. By applying SEM, ICP-AES, and water contact angle analysis, the effects of coating composition on the surface morphology and hydrophobicity of the as-prepared surfaces were detailedly studied. The results indicated that at the optimal condition, the surface showed a good superhydrophobicity with a water contact angle as high as 155.5 ± 1.3° and a sliding angle as low as about 3°. Possible growth mechanism of featherlike CuO hierarchical structure was discussed. Additionally, the anticorrosion effect of the superhydrophobic surface was studied by potentiodynamic polarization and electrochemical impedance spectroscopy (EIS) measurements. The interface model for anticorrosion mechanism of superhydrophobic surface in corrosive medium was proposed. Besides, the mechanical stability test indicated that the resulting superhydrophobic surfaces have good mechanical stability.

Investigation of the degradation mechanism of catalytic wires during oxidation of ammonia process

NASA Astrophysics Data System (ADS)

Pura, Jarosław; Wieciński, Piotr; Kwaśniak, Piotr; Zwolińska, Marta; Garbacz, Halina; Zdunek, Joanna; Laskowski, Zbigniew; Gierej, Maciej

2016-12-01

The most common catalysts for the ammonia oxidation process are 80 μm diameter platinum-rhodium wires knitted or woven into the form of a gauze. In an aggressive environment and under extreme conditions (temperature 800-900 °C, intensive gas flow, high pressure) precious elements are drained from the surface of the wires. Part of this separated material quickly decomposes on the surface in the form of characteristic "cauliflower-shape protrusions". The rest of the platinum is captured by palladium-nickel catalytic-capture gauzes located beneath. In our investigation we focused on the effects of the degradation of gauzes from one industrial catalytic system. The aim of the study was to compare the degree and the mechanism of degradation of gauzes from a different part of the reactor. The study covered PtRh7 catalytic and PdNi5 catalytic-capture gauzes. X-ray computer microtomography investigation revealed that despite strong differences in morphology, each Pt-Rh wire has a similar specific surface area. This indicates that the oxidation process and morphological changes of the wires occur in a self-regulating balance, resulting in the value of the specific surface area of the catalyst. Microtomography analysis of Pd-Ni wires revealed strong redevelopment of the wires' surface, which is related to the platinum capture phenomenon. Scanning electron microscope observations also revealed the nanostructure in the cauliflower-shape protrusions and large grains in the wires' preserved cores. The high temperature in the reactor and the long-term nature of the process do not favor the occurrence of the nanostructure in this type of material. Further and detailed analysis of this phenomena will provide a better understanding of the precious metals etching and deposition processes during oxidation.

Subsurface synthesis and characterization of Ag nanoparticles embedded in MgO

NASA Astrophysics Data System (ADS)

Vilayurganapathy, S.; Devaraj, A.; Colby, R.; Pandey, A.; Varga, T.; Shutthanandan, V.; Manandhar, S.; El-Khoury, P. Z.; Kayani, Asghar; Hess, W. P.; Thevuthasan, S.

2013-03-01

Metal nanoparticles exhibit a localized surface plasmon resonance (LSPR) which is very sensitive to the size and shape of the nanoparticle and the surrounding dielectric medium. The coupling between the electromagnetic radiation and the localized surface plasmon in metallic nanoparticles results in a sizable enhancement of the incident fields, making them possible candidates for plasmonic applications. In particular, partially exposed metallic nanoparticles distributed in a dielectric matrix can provide prime locations for LSPR spectroscopy and sensing. We report the synthesis and characterization of a plasmonic substrate consisting of Ag nanoparticles partially buried in MgO. Ag nanoparticles of different shapes and size distributions were synthesized below the surface of MgO by implanting 200 keV Ag+ ions followed by annealing at 1000 °C for 10 and 30 h. A detailed optical and structural characterization was carried out to understand the evolution of the Ag nanoparticle and size distribution inside the MgO matrix. Micro x-ray diffraction (Micro-XRD) was employed to investigate the structural properties and estimate the crystallite size. The nanoparticles evolved from a spherical to a faceted morphology with annealing time, assuming an octahedral shape truncated at the (001) planes, as visualized from aberration-corrected transmission electron microscopy (TEM) images. The nanoparticles embedded in MgO were shown to be pure metallic Ag using atom probe tomography (APT). The nanoparticles were partially exposed to the surface by employing plasma etch techniques to remove the overlaying MgO. Scanning electron microscopy (SEM) and atomic force microscopy (AFM) were employed to study the surface morphology and obtain a height distribution for the partially exposed nanoparticles.

Hominin teeth from the Middle Pleistocene site of Yiyuan, Eastern China.

PubMed

Xing, Song; Sun, Chengkai; Martinón-Torres, María; Bermúdez de Castro, José María; Han, Fei; Zhang, Yingqi; Liu, Wu

2016-06-01

In 1981-1982, some hominin fossils, including a relatively complete skull and seven isolated teeth, were recovered from the Middle Pleistocene site of Yiyuan in Eastern China. In the present study we provide a detailed metric and morphological comparison of the Yiyuan dental sample in order to characterize better the variability of the human populations that inhabited China during the Middle Pleistocene. Aside from taxonomic and phylogenetic questions, the lack of understanding and/or knowledge about the morphological variability of these populations have caused concern about the human versus non-human nature of some of the hominin dental remains found in East Asia during the Early and the Middle Pleistocene. Thus, our study aims to present a detailed description and comparison of the Yiyuan isolated teeth to 1) discuss and support their human nature and 2) to explore their taxonomic affinities with regard to other penecontemporaneous populations from Asia. Our results clearly differentiate the Yiyuan sample from Pongo specimens and support a human attribution for the Yiyuan material. Our analyses also suggest that the Yiyuan teeth form a morphologically coherent group together with samples from Zhoukoudian, Chaoxian and Hexian. They are different from the more derived specimens from Panxian Dadong, suggesting a pattern of biogeographic isolation and different evolutionary trends between northern and southern China during the Middle Pleistocene. In addition, and despite sharing a common morphological bauplan with Homo erectus sensu stricto (s.s.), the Yiyuan, Zhoukoudian and Hexian teeth are also different from the Indonesian Early Pleistocene samples. In particular, the expression of a highly crenulated or dendritic enamel-dentine surface could be unique to these groups. Our study supports the notion that the taxonomy of the Pleistocene hominins from Asia may have been oversimplified. Future studies should explore the variability of the Asian specimens and reconsider whether all the samples can be attributed to H. erectus s.s. Copyright © 2016 Elsevier Ltd. All rights reserved.

Rapid crystallization and morphological adjustment of zeolite ZSM-5 in nonionic emulsions

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

Zhang Ying, E-mail: yingzh1977@163.co; Jin Chao; Research Institute of Petroleum Processing, Beijing 100083

2011-01-15

Zeolite ZSM-5 was synthesized for the first time in a nonionic emulsion composed of polyoxyethylated alkylphenol, butanol, cyclohexane and tetraethylammonium hydroxide (TEAOH)-containing zeolite synthesis mixture. The crystallization kinetics in the emulsion was investigated and the ZSM-5 product was characterized in detail by XRD, SEM, FT-IR, TG, N{sub 2} adsorption and CHN analysis techniques. Compared with the conventionally hydrothermal synthesis with the same structure directing agent TEAOH, the emulsion system allows rapid crystallization of ZSM-5. The ZSM-5 product exhibits unusual agglomerated structure and possesses larger specific surface area. The FT-IR, TG results plus CHN analysis show the encapsulation of a tracemore » of emulsion components in the emulsion ZSM-5. Control experiments show the emulsion system exerts the crystallization induction and morphological adjustment effects mainly during the aging period. The effects are tentatively attributed to the confined space domains, surfactant-water interaction as well as surfactant-growing crystals interaction existing in the emulsion. -- Graphical abstract: The nonionic emulsion synthesis allows rapid crystallization and morphological adjustment of zeolite ZSM-5 compared with the conventional hydrothermal synthesis. Display Omitted« less

Optical spectroscopy combined with high-resolution magnetic resonance imaging for digestive wall assessment: endoluminal bimodal probe conception and characterization in vitro, on organic sample and in vivo on a rabbit

NASA Astrophysics Data System (ADS)

Ramgolam, Anoop; Sablong, Raphaël; Lafarge, Lionel; Saint-Jalmes, Hervé; Beuf, Olivier

2011-11-01

Colorectal cancer is a major health issue worldwide. Conventional white light endoscopy (WLE) coupled to histology is considered as the gold standard today and is the most widespread technique used for colorectal cancer diagnosis. However, during the early stages, colorectal cancer is very often characterized by flat adenomas which develop just underneath the mucosal surface. The use of WLE, which is heavily based on the detection of morphological changes, becomes quite delicate due to subtle or quasi-invisible morphological changes of the colonic lining. Several techniques are currently being investigated in the scope of providing new tools that would allow such a diagnostic or assist actual techniques in so doing. We hereby present a novel technique where high spatial resolution MRI is combined with autofluorescence and reflectance spectroscopy in a bimodal endoluminal probe to extract morphological data and biochemical information, respectively. The design and conception of the endoluminal probe are detailed and the promising preliminary results obtained in vitro (home-built phantom containing eosin and rhodamine B), on an organic sample (the kiwi fruit) and in vivo on a rabbit are presented and discussed.

Effect of SiO2 coating layer morphology on TiH2 gas release characteristic.

PubMed

Yang, Zhimao; Fang, Jixiang; Ding, Bingjun

2005-10-15

In this study, a uniform and compact SiO2 film-coating layer was prepared on the surface of TiH2 particles by sol-gel method using inexpensive raw materials. The preparation process of SiO2-coated TiH2 particles and the effect of the coating layer morphology on the gas release characteristic were investigated in detail. When the pH value of TiH2 suspending solution is about 4.0 and the concentration of silicic acid is more than 0.5 mol/L, the coating layer shows a SiO2 particle-coating morphology. While a homogeneous and dense film-coating layer can be obtained when the solution pH value and concentration of silicic acid are about 4.0 and 0.5 mol/L. The results of gas release at 700 degrees C show that TiH2 particles coated with silicon dioxide layers can efficiently delay the starting time of gas release of TiH2 powders to 60-100 s. Comparing the particle-coating layer, the SiO2 film-coating layer has a better delaying effect on gas release of TiH2 particles.

Role of Crystallization in the Morphology of Polymer: Non-fullerene Acceptor Bulk Heterojunctions

DOE PAGES

O’Hara, Kathryn A.; Ostrowski, David P.; Koldemir, Unsal; ...

2017-05-22

Many high efficiency organic photovoltaics use fullerene-based acceptors despite their high production cost, weak optical absorption in the visible range, and limited synthetic variability of electronic and optical properties. To circumvent this deficiency, non-fullerene small-molecule acceptors have been developed that have good synthetic flexibility, allowing for precise tuning of optoelectronic properties, leading to enhanced absorption of the solar spectrum and increased open-circuit voltages ( V OC). We examined the detailed morphology of bulk heterojunctions of poly(3-hexylthiophene) and the small-molecule acceptor HPI-BT to reveal structural changes that lead to improvements in the fill factor of solar cells upon thermal annealing. Themore » kinetics of the phase transformation process of HPI-BT during thermal annealing were investigated through in situ grazing incidence wide-angle X-ray scattering studies, atomic force microscopy, and transmission electron microscopy. The HPI-BT acceptor crystallizes during film formation to form micron-sized domains embedded within the film center and a donor rich capping layer at the cathode interface reducing efficient charge extraction. Thermal annealing changes the surface composition and improves charge extraction. In conclusion, this study reveals the need for complementary methods to investigate the morphology of BHJs.« less

Role of Crystallization in the Morphology of Polymer: Non-fullerene Acceptor Bulk Heterojunctions

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

O’Hara, Kathryn A.; Ostrowski, David P.; Koldemir, Unsal

Many high efficiency organic photovoltaics use fullerene-based acceptors despite their high production cost, weak optical absorption in the visible range, and limited synthetic variability of electronic and optical properties. To circumvent this deficiency, non-fullerene small-molecule acceptors have been developed that have good synthetic flexibility, allowing for precise tuning of optoelectronic properties, leading to enhanced absorption of the solar spectrum and increased open-circuit voltages ( V OC). We examined the detailed morphology of bulk heterojunctions of poly(3-hexylthiophene) and the small-molecule acceptor HPI-BT to reveal structural changes that lead to improvements in the fill factor of solar cells upon thermal annealing. Themore » kinetics of the phase transformation process of HPI-BT during thermal annealing were investigated through in situ grazing incidence wide-angle X-ray scattering studies, atomic force microscopy, and transmission electron microscopy. The HPI-BT acceptor crystallizes during film formation to form micron-sized domains embedded within the film center and a donor rich capping layer at the cathode interface reducing efficient charge extraction. Thermal annealing changes the surface composition and improves charge extraction. In conclusion, this study reveals the need for complementary methods to investigate the morphology of BHJs.« less

Interaction between Cities and Climate Change: Modelling Urban Morphology and Local Urban Planning Scenarios from Open Datasets across European Cities

NASA Astrophysics Data System (ADS)

Thomas, Bart; Stevens, Catherine; Grommen, Mart

2015-04-01

Cities are characterised by a large spatiotemporal diversity of local climates induced by a superposition of various factors and processes interacting at global and regional scales but also at the micro level such as the urban heat island effect. As urban areas are known as 'hot spots' prone to climate and its variability over time leading to changes in the severity and occurrence of extreme events such as heat waves, it is of crucial importance to capture the spatial heterogeneity resulting from variations in land use land cover (LULC) and urban morphology in an effective way to drive local urban climate simulations. The first part of the study conducted in the framework of the NACLIM FP7 project funded by the European Commission focusses on the extraction of land surface parameters linked to urban morphology characteristics from detailed 3D city models and their relationship with openly accessible European datasets such as the degree of soil sealing and disaggregated population densities from the European Environment Agency (EEA) and the Joint Research Centre (JRC). While it has been demonstrated that good correlations can be found between those datasets and the planar and frontal area indices, the present work has expanded the research to other urban morphology parameters including the average and variation of the building height and the sky view factor. Correlations up to 80% have been achieved depending on the considered parameter and the specific urban area including the cities of Antwerp (Belgium), Berlin (Germany) and Almada (Portugal) represented by different climate and urban characteristics. Moreover, the transferability of the established relations has been investigated across the various cities. Secondly, a flexible and scalable approach as a function of the required the level of detail has been elaborated to update the various morphology parameters in case of integration with urban planning data to analyse the local impact of future land use scenarios, climate adaptation strategies and mitigation measures in an effective way by comparing the future occupation of the soil against metrics derived from existing soil sealing data from the EEA.

Nickel antimony oxide (NiSb2O6): A fascinating nanostructured material for gas sensing application

NASA Astrophysics Data System (ADS)

Singh, Archana; Singh, Ajendra; Singh, Satyendra; Tandon, Poonam

2016-02-01

Fabrication of nanocrystalline NiSb2O6 thin films via sol-gel spin coating method towards the development of liquefied petroleum gas (LPG) sensor operable at room temperature (25 °C) is being reported. Nanostructural, surface morphological and optical properties of trirutile-type NiSb2O6 have been investigated in order to explore the parameters of interest. The crystallite size has been found to be 19 nm. A detailed sensing performance (sensitivity, sensor response, response and recovery times, reproducibility and long term stability) of NiSb2O6 nanostructures grown on alumina substrate has been investigated.

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.

A modular reactor to simulate biofilm development in orthopedic materials.

PubMed

Barros, Joana; Grenho, Liliana; Manuel, Cândida M; Ferreira, Carla; Melo, Luís F; Nunes, Olga C; Monteiro, Fernando J; Ferraz, Maria P

2013-09-01

Surfaces of medical implants are generally designed to encourage soft- and/or hard-tissue adherence, eventually leading to tissue- or osseo-integration. Unfortunately, this feature may also encourage bacterial adhesion and biofilm formation. To understand the mechanisms of bone tissue infection associated with contaminated biomaterials, a detailed understanding of bacterial adhesion and subsequent biofilm formation on biomaterial surfaces is needed. In this study, a continuous-flow modular reactor composed of several modular units placed in parallel was designed to evaluate the activity of circulating bacterial suspensions and thus their predilection for biofilm formation during 72 h of incubation. Hydroxyapatite discs were placed in each modular unit and then removed at fixed times to quantify biofilm accumulation. Biofilm formation on each replicate of material, unchanged in structure, morphology, or cell density, was reproducibly observed. The modular reactor therefore proved to be a useful tool for following mature biofilm formation on different surfaces and under conditions similar to those prevailing near human-bone implants.

Enhanced flyby science with onboard computer vision: Tracking and surface feature detection at small bodies

NASA Astrophysics Data System (ADS)

Fuchs, Thomas J.; Thompson, David R.; Bue, Brian D.; Castillo-Rogez, Julie; Chien, Steve A.; Gharibian, Dero; Wagstaff, Kiri L.

2015-10-01

Spacecraft autonomy is crucial to increase the science return of optical remote sensing observations at distant primitive bodies. To date, most small bodies exploration has involved short timescale flybys that execute prescripted data collection sequences. Light time delay means that the spacecraft must operate completely autonomously without direct control from the ground, but in most cases the physical properties and morphologies of prospective targets are unknown before the flyby. Surface features of interest are highly localized, and successful observations must account for geometry and illumination constraints. Under these circumstances onboard computer vision can improve science yield by responding immediately to collected imagery. It can reacquire bad data or identify features of opportunity for additional targeted measurements. We present a comprehensive framework for onboard computer vision for flyby missions at small bodies. We introduce novel algorithms for target tracking, target segmentation, surface feature detection, and anomaly detection. The performance and generalization power are evaluated in detail using expert annotations on data sets from previous encounters with primitive bodies.

Self-organizing layers from complex molecular anions

DOE PAGES

Warneke, Jonas; McBriarty, Martin E.; Riechers, Shawn L.; ...

2018-05-14

The formation of traditional ionic materials occurs principally via joint accumulation of both anions and cations. Here in this paper, we describe a previously unreported phenomenon by which macroscopic liquid-like thin layers with tunable self-organization properties form through accumulation of stable complex ions of one polarity on surfaces. Using a series of highly stable molecular anions we demonstrate a strong influence of the internal charge distribution of the molecular ions, which is usually shielded by counterions, on the properties of the layers. Detailed characterization reveals that the intrinsically unstable layers of anions on surfaces are stabilized by simultaneous accumulation ofmore » neutral molecules from the background environment. Different phases, self-organization mechanisms and optical properties are observed depending on the molecular properties of the deposited anions, the underlying surface and the coadsorbed neutral molecules. This demonstrates rational control of the macroscopic properties (morphology and size of the formed structures) of the newly discovered anion-based layers.« less

Detrended Topographic Data of the South-pole Aitken Basin (SPA): Comparisons with Apollo 16 and Schiller-Schickard as Indications of the Formation and Evolution of the Spa Interior

NASA Technical Reports Server (NTRS)

Petro, N. E.; Hollibaugh-Baker, D.; Jolliff, B. L.

2017-01-01

Data from recent lunar orbital missions have provided critical insight into the surface composition, morphology, and geologic history of the Moon. A key region that has benefited from this new data is the South Pole-Aitken Basin (SPA), a key area for future sample return]. A key area of investigation of SPA has been the characterization of its surface, detailing the interior composition, geologic evolution, and possible exposure of deep-seated materials. Recently we have applied a number of datasets to ascertain the origin of surfaces in central SPA and identify units that represent the ancient SPA-derived impact melt and those that represent volcanic activity. Here we apply a technique that utilizes high-resolution topographic data to remove local slopes to highlight subtle topographic variations. Such detrended data allows us to characterize units that are either ancient (SPA impact melt) or that represent subsequent volcanic activity.

Self-organizing layers from complex molecular anions

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

Warneke, Jonas; McBriarty, Martin E.; Riechers, Shawn L.

The formation of traditional ionic materials occurs principally via joint accumulation of both anions and cations. Here in this paper, we describe a previously unreported phenomenon by which macroscopic liquid-like thin layers with tunable self-organization properties form through accumulation of stable complex ions of one polarity on surfaces. Using a series of highly stable molecular anions we demonstrate a strong influence of the internal charge distribution of the molecular ions, which is usually shielded by counterions, on the properties of the layers. Detailed characterization reveals that the intrinsically unstable layers of anions on surfaces are stabilized by simultaneous accumulation ofmore » neutral molecules from the background environment. Different phases, self-organization mechanisms and optical properties are observed depending on the molecular properties of the deposited anions, the underlying surface and the coadsorbed neutral molecules. This demonstrates rational control of the macroscopic properties (morphology and size of the formed structures) of the newly discovered anion-based layers.« less

Laser synthesized super-hydrophobic conducting carbon with broccoli-type morphology as a counter-electrode for dye sensitized solar cells

NASA Astrophysics Data System (ADS)

Gokhale, Rohan; Agarkar, Shruti; Debgupta, Joyashish; Shinde, Deodatta; Lefez, Benoit; Banerjee, Abhik; Jog, Jyoti; More, Mahendra; Hannoyer, Beatrice; Ogale, Satishchandra

2012-10-01

A laser photochemical process is introduced to realize superhydrophobic conducting carbon coatings with broccoli-type hierarchical morphology for use as a metal-free counter electrode in a dye sensitized solar cell. The process involves pulsed excimer laser irradiation of a thin layer of liquid haloaromatic organic solvent o-dichlorobenzene (DCB). The coating reflects a carbon nanoparticle-self assembled and process-controlled morphology that yields solar to electric power conversion efficiency of 5.1% as opposed to 6.2% obtained with the conventional Pt-based electrode.A laser photochemical process is introduced to realize superhydrophobic conducting carbon coatings with broccoli-type hierarchical morphology for use as a metal-free counter electrode in a dye sensitized solar cell. The process involves pulsed excimer laser irradiation of a thin layer of liquid haloaromatic organic solvent o-dichlorobenzene (DCB). The coating reflects a carbon nanoparticle-self assembled and process-controlled morphology that yields solar to electric power conversion efficiency of 5.1% as opposed to 6.2% obtained with the conventional Pt-based electrode. Electronic supplementary information (ESI) available: Materials and equipment details, solar cell fabrication protocol, electrolyte spreading time measurement details, XPS spectra, electronic study, film adhesion test detailed analysis and field emission results. See DOI: 10.1039/c2nr32082g

Hydrophobic pinning with copper nanowhiskers leads to bactericidal properties.

PubMed

Singh, Ajay Vikram; Baylan, Semanur; Park, Byung-Wook; Richter, Gunther; Sitti, Metin

2017-01-01

The considerable morbidity associated with hospitalized patients and clinics in developed countries due to biofilm formation on biomedical implants and surgical instruments is a heavy economic burden. An alternative to chemically treated surfaces for bactericidal activity started emerging from micro/nanoscale topographical cues in the last decade. Here, we demonstrate a putative antibacterial surface using copper nanowhiskers deposited by molecular beam epitaxy. Furthermore, the control of biological response is based on hydrophobic pinning of water droplets in the Wenzel regime, causing mechanical injury and cell death. Scanning electron microscopy images revealed the details of the surface morphology and non-contact mode laser scanning of the surface revealed the microtopography-associated quantitative parameters. Introducing the bacterial culture over nanowhiskers produces mechanical injury to cells, leading to a reduction in cell density over time due to local pinning of culture medium to whisker surfaces. Extended culture to 72 hours to observe biofilm formation revealed biofilm inhibition with scattered microcolonies and significantly reduced biovolume on nanowhiskers. Therefore, surfaces patterned with copper nanowhiskers can serve as potential antibiofilm surfaces. The topography-based antibacterial surfaces introduce a novel prospect in developing mechanoresponsive nanobiomaterials to reduce the risk of medical device biofilm-associated infections, contrary to chemical leaching of copper as a traditional bactericidal agent.

Thermally controlled growth of surface nanostructures on ion-modified AIII-BV semiconductor crystals

NASA Astrophysics Data System (ADS)

Trynkiewicz, Elzbieta; Jany, Benedykt R.; Wrana, Dominik; Krok, Franciszek

2018-01-01

The primary motivation for our systematic study is to provide a comprehensive overview of the role of sample temperature on the pattern evolution of several AIII-BV semiconductor crystal (001) surfaces (i.e., InSb, InP, InAs, GaSb) in terms of their response to low-energy Ar+ ion irradiation conditions. The surface morphology and the chemical diversity of such ion-modified binary materials has been characterized by means of scanning electron microscopy (SEM). In general, all surface textures following ion irradiation exhibit transitional behavior from small islands, via vertically oriented 3D nanostructures, to smoothened surface when the sample temperature is increased. This result reinforces our conviction that the mass redistribution of adatoms along the surface plays a vital role during the formation and growth process of surface nanostructures. We would like to emphasize that this paper addresses in detail for the first time the topic of the growth kinetics of the nanostructures with regard to thermal surface diffusion, while simultaneously offering some possible approaches to supplementing previous studies and therein gaining a new insight into this complex issue. The experimental results are discussed with reference to models of the pillars growth, abutting on preferential sputtering, the self-sustained etch masking effect and the redeposition process recently proposed to elucidate the observed nanostructuring mechanism.

Description of Rhodnius marabaensis sp. n. (Hemiptera, Reduviidae, Triatominae) from Pará State, Brazil

PubMed Central

Souza, Eder dos Santos; Von Atzingen, Noé Carlos Barbosa; Furtado, Maria Betânia; de Oliveira, Jader; Nascimento, Juliana Damieli; Vendrami, Daniel Pagotto; Gardim, Sueli; da Rosa, João Aristeu

2016-01-01

Abstract Rhodnius marabaensis sp. n. was collected on 12 May 2014 in the Murumurú Environmental Reserve in the city of Marabá, Pará State, Brazil. This study was based on previous consultation of morphological descriptions of 19 Rhodnius species and compared to the identification key for the genus Rhodnius. The examination included specimens from 18 Rhodnius species held in the Brazilian National and International Triatomine Taxonomy Reference Laboratory in the Oswaldo Cruz Institute in Rio de Janeiro, Brazil. The morphological characteristics of the head, thorax, abdomen, genitalia, and eggs have been determined. Rhodnius prolixus and Rhodnius robustus were examined in more detail because the BLAST analysis of a cyt-b sequence shows they are closely related to the new species, which also occurs in the northern region of Brazil. The most notable morphological features that distinguish Rhodnius marabaensis sp. n. are the keel-shaped apex of the head, the length of the second segment of the antennae, the shapes of the prosternum, mesosternum and metasternum, the set of spots on the abdomen, the male genitalia, the posterior and ventral surfaces of the external female genitalia, and the morphological characteristics of the eggs. Rhodnius jacundaensis Serra, Serra & Von Atzingen (1980) nomen nudum specimens deposited at the Maraba Cultural Center Foundation - MCCF were examined and considered as a synonym of Rhodnius marabaensis sp. n. PMID:27833419

Electrospinning of gelatin with tunable fiber morphology from round to flat/ribbon.

PubMed

Topuz, Fuat; Uyar, Tamer

2017-11-01

The electrospinning of gelatin with tunable fiber morphology from round to flat/ribbon was shown, and the detailed studies were conducted to correlate the fiber morphology with electrospinning process parameters and gelatin concentration in electrospinning solution. Particularly, variations in the applied voltage and the concentration of gelatin led to the transition of fiber shape from round to flat/ribbon. The formation of flat-shaped fibers was attributed to rapid evaporation of the solvent (formic acid) from the fiber matrix with increasing the applied voltage and gelatin concentration. On the other hand, round fibers were due to the steady evaporation of formic acid throughout the cross-section of fibers. WAXS analysis revealed that the loss of triple-helical crystalline structure in gelatin after the electrospinning process. The gelatin fibers were cross-linked through treatment with toluene 2,4-diisocyanate (TDI) in a mixed solution of acetone and pyridine, and XPS confirmed the cross-linking of the fibers over an increased carbon content on the elemental composition of the fiber surface due to the incorporated TDI moieties. Overall, this study focuses on morphological tuning of gelatin electrospun fibers towards a flat/ribbon-like structure by variation of electrospinning parameters and polymer concentration, and thus, the proposed concept can be adapted towards flattened/ribbon-like fibers of other protein-based systems by electrospinning. Copyright © 2017 Elsevier B.V. All rights reserved.

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.

3-D Structure and Morphology of the S-reflector Detachment Fault, Offshore Galicia, Spain

NASA Astrophysics Data System (ADS)

Schuba, C. N.; Sawyer, D. S.; Gray, G. G.; Morgan, J.; Bull, J.; Shillington, D. J.; Jordan, B.; Reston, T. J.

2017-12-01

The crustal architecture of passive continental margins provides valuable clues for understanding rift initiation and evolution. The Galicia margin is an archetypal magma-poor margin displaying exhumed serpentinized mantle, and is an optimal setting in which to examine rift-related processes. A new 3-D seismic reflection volume images this margin in great detail. The S-reflector detachment fault, one of the most prominent structural features associated with the Galicia margin, is imaged as a continuous interface over an area of 600 km2. The top and base of the fault zone can be mapped independently, which enables seismic attribute analysis of this significant structure. RMS amplitude maps extracted from this interface show localized patches of high amplitude stripes that coincide with thickness variations of the fault zone and undulations in the bounding surfaces of the fault. These variations bear similarities to grooves on the fault surface such as slickensides, and appear to have developed as the fault zone evolved. These features thus represent good indicators of the kinematics of the fault system. In general, there is good correlation between S-reflector morphology and the overriding fault intersections; however this relationship does not appear to be present with the fault gouge thickness.

Morphology of the limbs in the semi-fossorial desert rodent species of Tympanoctomys (Octodontidae, Rodentia)

PubMed Central

Perez, M. Julieta; Barquez, Ruben M.; Diaz, M. Monica

2017-01-01

Abstract Here, a detailed description of the forelimbs and hindlimbs of all living species of the genus Tympanoctomys are presented. These rodents, highly adapted to desert environments, are semi-fossorial with capacity to move on the surface as well as to build burrows. The shape, structure, and size of the limbs are described. Contrary to what was expected for scratch digging semi-fossorial species, Tympanoctomys have slender humerus, radius and ulna; with narrow epicondyles of the humerus and short olecranon of the ulna with poorly developed processes. Following our descriptions, no intrageneric morphological variation regarding to the configuration of the limbs was detected, probably due to phylogenetic proximity, and not related to specific variations in response to different use of substrates or habits. The obtained results constitute a source of previously unpublished information as well as an important base for future analysis in different studies, such as morphometric, morpho-functional, or phylogenetic researches. PMID:29118644

Galvanostatic Intermittent Titration and Performance Based Analysis of LiNi 0.5 Co 0.2 Mn 0.3 O 2 Cathode

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

Verma, Ankit; Smith, Kandler; Santhanagopalan, Shriram

Galvanostatic intermittent titration technique (GITT) - a popular method for characterizing kinetic and transport properties of battery electrodes - is predicated on the proper evaluation of electrode active area. LiNi 0.5044Co 0.1986Mn 0.2970O 2 (NCM523) material exhibits a complex morphology in which sub-micron primary particles aggregate to form secondary particle agglomerates. Our work proposes a new active area formulation for primary/secondary particle agglomerate materials to better mimic the morphology of NCM532 electrodes. Furthermore, this formulation is then coupled with macro-homogeneous models to simulate GITT and half-cell performance of NCM523 electrodes. Subsequently, the model results are compared against the experimental resultsmore » to refine the area formulation. A single parameter, the surface roughness factor, is proposed to mimic the change in interfacial area, diffusivity and exchange current density simultaneously and detailed modeling results are presented to provide valuable insights into the efficacy of the formulation.« less

Galvanostatic Intermittent Titration and Performance Based Analysis of LiNi 0.5Co 0.2 Mn 0.3O 2Cathode

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

Verma, Ankit; Smith, Kandler; Santhanagopalan, Shriram

Galvanostatic intermittent titration technique (GITT) – a popular method for characterizing kinetic and transport properties of battery electrodes – is predicated on the proper evaluation of electrode active area. LiNi0.5044Co0.1986Mn0.2970O2 (NCM523) material exhibits a complex morphology in which sub-micron primary particles aggregate to form secondary particle agglomerates. This work proposes a new active area formulation for primary/secondary particle agglomerate materials to better mimic the morphology of NCM532 electrodes. This formulation is then coupled with macro-homogeneous models to simulate GITT and half-cell performance of NCM523 electrodes. Subsequently, the model results are compared against the experimental results to refine the area formulation.more » A single parameter, the surface roughness factor, is proposed to mimic the change in interfacial area, diffusivity and exchange current density simultaneously and detailed modeling results are presented to provide valuable insights into the efficacy of the formulation.« less

Evaluation of SiO{sub 2}@CoFe{sub 2}O{sub 4} nano-hollow spheres through THz pulses

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

Rakshit, Rupali, E-mail: rupali12@bose.res.in; Pal, Monalisa; Chaudhuri, Arka

2016-05-06

We have synthesized cobalt ferrite (CFO) nanoparticles (NPs) of diameter 100 nm and nano-hollow spheres (NHSs) of diameter 100, 160, 250, and 350 nm by a facile one step template free solvothermal technique and carried out SiO{sub 2} coating on their surface following Stöber method. The phase and morphology of the nanostructures were confirmed by X-ray diffraction and transmission electron microscope. The magnetic measurements were carried out by vibrating sample magnetometer in order to study the influence of SiO{sub 2} coating on the magnetic properties of bare CFO nanostructures. Furthermore, we have applied THz time domain spectroscopy to investigate the THz absorptionmore » property of these nanostructures in the frequency range 1.0–2.5 THz. Detailed morphology and size dependent THz absorption study unfolds that the absorption property of these nanostructures sensitively carries the unique signature of its dielectric property.« less

Highly effective field-effect mobility amorphous InGaZnO TFT mediated by directional silver nanowire arrays.

PubMed

Liu, Hung-Chuan; Lai, Yi-Chun; Lai, Chih-Chung; Wu, Bing-Shu; Zan, Hsiao-Wen; Yu, Peichen; Chueh, Yu-Lun; Tsai, Chuang-Chuang

2015-01-14

In this work, we demonstrate sputtered amorphous indium-gallium-zinc oxide thin-film transistors (a-IGZO TFTs) with a record high effective field-effect mobility of 174 cm(2)/V s by incorporating silver nanowire (AgNW) arrays to channel electron transport. Compared to the reference counterpart without nanowires, the over 5-fold enhancement in the effective field-effect mobility exhibits clear dependence on the orientation as well as the surface coverage ratio of silver nanowires. Detailed material and device analyses reveal that during the room-temperature IGZO sputtering indium and oxygen diffuse into the nanowire matrix while the nanowire morphology and good contact between IGZO and nanowires are maintained. The unchanged morphology and good interfacial contact lead to high mobility and air-ambient-stable characteristics up to 3 months. Neither hysteresis nor degraded bias stress reliability is observed. The proposed AgNW-mediated a-IGZO TFTs are promising for development of large-scale, flexible, transparent electronics.

Galvanostatic Intermittent Titration and Performance Based Analysis of LiNi 0.5 Co 0.2 Mn 0.3 O 2 Cathode

DOE PAGES

Verma, Ankit; Smith, Kandler; Santhanagopalan, Shriram; ...

2017-11-03

Galvanostatic intermittent titration technique (GITT) - a popular method for characterizing kinetic and transport properties of battery electrodes - is predicated on the proper evaluation of electrode active area. LiNi 0.5044Co 0.1986Mn 0.2970O 2 (NCM523) material exhibits a complex morphology in which sub-micron primary particles aggregate to form secondary particle agglomerates. Our work proposes a new active area formulation for primary/secondary particle agglomerate materials to better mimic the morphology of NCM532 electrodes. Furthermore, this formulation is then coupled with macro-homogeneous models to simulate GITT and half-cell performance of NCM523 electrodes. Subsequently, the model results are compared against the experimental resultsmore » to refine the area formulation. A single parameter, the surface roughness factor, is proposed to mimic the change in interfacial area, diffusivity and exchange current density simultaneously and detailed modeling results are presented to provide valuable insights into the efficacy of the formulation.« less

Studies on morphology, electrical and optical characteristics of Al-doped ZnO thin films grown by atomic layer deposition

NASA Astrophysics Data System (ADS)

Chen, Li; Chen, Xinliang; Zhou, Zhongxin; Guo, Sheng; Zhao, Ying; Zhang, Xiaodan

2018-03-01

Al doped ZnO (AZO) films deposited on glass substrates through the atomic layer deposition (ALD) technique are investigated with various temperatures from 100 to 250 °C and different Zn : Al cycle ratios from 20 : 0 to 20 : 3. Surface morphology, structure, optical and electrical properties of obtained AZO films are studied in detail. The Al composition of the AZO films is varied by controlling the ratio of Zn : Al. We achieve an excellent AZO thin film with a resistivity of 2.14 × 10‑3 Ω·cm and high optical transmittance deposited at 150 °C with 20 : 2 Zn : Al cycle ratio. This kind of AZO thin films exhibit great potential for optoelectronics device application. Project supported by the State Key Development Program for Basic Research of China (Nos. 2011CBA00706, 2011CBA00707) and the Tianjin Applied Basic Research Project and Cutting-Edge Technology Research Plan (No. 13JCZDJC26900).

Quantifying Morphological Parameters of the Terminal Branching Units in a Mouse Lung by Phase Contrast Synchrotron Radiation Computed Tomography

PubMed Central

Hwang, Jeongeun; Kim, Miju; Kim, Seunghwan; Lee, Jinwon

2013-01-01

An effective technique of phase contrast synchrotron radiation computed tomography was established for the quantitative analysis of the microstructures in the respiratory zone of a mouse lung. Heitzman’s method was adopted for the whole-lung sample preparation, and Canny’s edge detector was used for locating the air-tissue boundaries. This technique revealed detailed morphology of the respiratory zone components, including terminal bronchioles and alveolar sacs, with sufficiently high resolution of 1.74 µm isotropic voxel size. The technique enabled visual inspection of the respiratory zone components and comprehension of their relative positions in three dimensions. To check the method’s feasibility for quantitative imaging, morphological parameters such as diameter, surface area and volume were measured and analyzed for sixteen randomly selected terminal branching units, each consisting of a terminal bronchiole and a pair of succeeding alveolar sacs. The four types of asymmetry ratios concerning alveolar sac mouth diameter, alveolar sac surface area, and alveolar sac volume are measured. This is the first ever finding of the asymmetry ratio for the terminal bronchioles and alveolar sacs, and it is noteworthy that an appreciable degree of branching asymmetry was observed among the alveolar sacs at the terminal end of the airway tree, despite the number of samples was small yet. The series of efficient techniques developed and confirmed in this study, from sample preparation to quantification, is expected to contribute to a wider and exacter application of phase contrast synchrotron radiation computed tomography to a variety of studies. PMID:23704918

Comparative morphology and histology of the nasal fossa in four mammals: gray squirrel, bobcat, coyote and white-tailed deer

PubMed Central

Yee, Karen K.; Craven, Brent A.; Wysocki, Charles J.; Van Valkenburgh, Blaire

2016-01-01

Although the anatomy of the nasal fossa is broadly similar among terrestrial mammals, differences are evident in the intricacies of nasal turbinal architecture, which varies from simple scroll-like to complex branching forms, and in the extent of nonsensory and olfactory epithelium covering the turbinals. In this study, detailed morphological and immunohistochemical examinations and quantitative measurements of the turbinals and epithelial lining of the nasal fossa were conducted in an array of species that include the gray squirrel, bobcat, coyote, and white-tailed deer. Results show that much more of the nose is lined with olfactory epithelium in the smallest species (gray squirrel) than in the larger species. In two species with similar body masses, bobcat and coyote, the foreshortened felid snout influences turbinal size and results in a decrease of olfactory epithelium on the ethmoturbinals relative to the longer canine snout. Ethmoturbinal surface area exceeds that of the maxilloturbinals in all four sampled animals, except the white-tailed deer, in which the two are similar in size. Combining our results with published data from a broader array of mammalian noses, it is apparent that olfactory epithelial surface area is influenced by body mass, but is also affected by aspects of life history, such as diet and habitat, as well as skull morphology, itself a product of multiple compromises between various functions, such as feeding, vision, and cognition. The results of this study warrant further examination of other mammalian noses to broaden our evolutionary understanding of nasal fossa anatomy. PMID:27090617

Nanoscale morphology of Ni{sub 50}Ti{sub 45}Cu{sub 5} nanoglass

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

Śniadecki, Z., E-mail: sniadecki@ifmpan.poznan.pl; Institute of Nanotechnology, Karlsruhe Institute of Technology, Hermann-von-Helmholtz-Platz 1, D-76344 Eggenstein-Leopoldshafen; Wang, D.

2016-03-15

Nanoglasses are noncrystalline solids with a granular nano-/microstructure. In contrast to their nanocrystalline analogs, typically constituted of grains and grain boundaries, nanoglasses consist of glassy regions with a structure corresponding to melt-quenched glasses and amorphous interfaces characterized by a reduced density. Their unique properties can be controlled by modifying size and chemical composition of the granular and interfacial regions. Ni{sub 50}Ti{sub 45}Cu{sub 5} amorphous films were obtained by magnetron sputtering and analyzed to determine their nanoscale morphology and the formation mechanisms. The nanoglasses were noted to have a hierarchical nano-columnar structure with the smallest Ni-rich (Ni:Ti ratio of ca. 5:3)more » amorphous columns with diameters of about 8 nm and Ti-rich glassy interfacial regions with a substantially lower density. The results were obtained utilizing X-ray diffraction and different microscopic methods, e.g., atomic force microscopy and transmission electron microscopy. A detailed analysis indicates the complexity of the formation mechanisms of topologically and chemically distinguishable structural units with curvature driven surface diffusion, surface mobility, self-shadowing and internal stresses as the most important parameters. Common and simple synthesis method and the possibility for easy modification of the morphology and, consequently, the physical properties offer an opportunity for intensive studies of this new class of materials, opening the way towards possible applications. - Highlights: • Ni{sub 50}Ti{sub 45}Cu{sub 5} thin film nanoglasses were synthesized by magnetron sputtering. • Ti amorphous interfacial phase with reduced density is observed. • Stabilization of interfaces by specific local thermodynamic conditions.« less

Femoral morphology and femoropelvic musculoskeletal anatomy of humans and great apes: a comparative virtopsy study.

PubMed

Morimoto, Naoki; Ponce de León, Marcia S; Nishimura, Takeshi; Zollikofer, Christoph P E

2011-09-01

The proximal femoral morphology of fossil hominins is routinely interpreted in terms of muscular topography and associated locomotor modes. However, the detailed correspondence between hard and soft tissue structures in the proximal femoral region of extant great apes is relatively unknown, because dissection protocols typically do not comprise in-depth osteological descriptions. Here, we use computed tomography and virtopsy (virtual dissection) for non-invasive examination of the femoropelvic musculoskeletal anatomy in Pan troglodytes, P. paniscus, Gorilla gorilla, Pongo pygmaeus, and Homo sapiens. Specifically, we analyze the topographic relationship between muscle attachment sites and surface structures of the proximal femoral shaft such as the lateral spiral pilaster. Our results show that the origin of the vastus lateralis muscle is anterior to the insertion of gluteus maximus in all examined great ape specimens and humans. In gorillas and orangutans, the insertion of gluteus maximus is on the inferior (anterolateral) side of the lateral spiral pilaster. In chimpanzees, however, the maximus insertion is on its superior (posteromedial) side, similar to the situation in modern humans. These findings support the hypothesis that chimpanzees and humans exhibit a shared-derived musculoskeletal topography of the proximal femoral region, irrespective of their different locomotor modes, whereas gorillas and orangutans represent the primitive condition. Caution is thus warranted when inferring locomotor behavior from the surface topography of the proximal femur of fossil hominins, as the morphology of this region may contain a strong phyletic signal that tends to blur locomotor adaptation. Copyright © 2011 Wiley-Liss, Inc.

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.

Molecular basis of crystal morphology-dependent adhesion behavior of mefenamic acid during tableting.

PubMed

Waknis, Vrushali; Chu, Elza; Schlam, Roxana; Sidorenko, Alexander; Badawy, Sherif; Yin, Shawn; Narang, Ajit S

2014-01-01

The molecular basis of crystal surface adhesion leading to sticking was investigated by exploring the correlation of crystal adhesion to oxidized iron coated atomic force microscope (AFM) tips and bulk powder sticking behavior during tableting of two morphologically different crystals of a model drug, mefenamic acid (MA), to differences in their surface functional group orientation and energy. MA was recrystallized into two morphologies (plates and needles) of the same crystalline form. Crystal adhesion to oxidized iron coated AFM tips and bulk powder sticking to tablet punches was assessed using a direct compression formulation. Surface functional group orientation and energies on crystal faces were modeled using Accelrys Material Studio software. Needle-shaped morphology showed higher sticking tendency than plates despite similar particle size. This correlated with higher crystal surface adhesion of needle-shaped morphology to oxidized iron coated AFM probe tips, and greater surface energy and exposure of polar functional groups. Higher surface exposure of polar functional groups correlates with higher tendency to stick to metal surfaces and AFM tips, indicating involvement of specific polar interactions in the adhesion behavior. In addition, an AFM method is identified to prospectively assess the risk of sticking during the early stages of drug development.

Reactive solid surface morphology variation via ionic diffusion.

PubMed

Sun, Zhenchao; Zhou, Qiang; Fan, Liang-Shih

2012-08-14

In gas-solid reactions, one of the most important factors that determine the overall reaction rate is the solid morphology, which can be characterized by a combination of smooth, convex and concave structures. Generally, the solid surface structure varies in the course of reactions, which is classically noted as being attributed to one or more of the following three mechanisms: mechanical interaction, molar volume change, and sintering. Here we show that if a gas-solid reaction involves the outward ionic diffusion of a solid-phase reactant then this outward ionic diffusion could eventually smooth the surface with an initial concave and/or convex structure. Specifically, the concave surface is filled via a larger outward diffusing surface pointing to the concave valley, whereas the height of the convex surface decreases via a lower outward diffusion flux in the vertical direction. A quantitative 2-D continuum diffusion model is established to analyze these two morphological variation processes, which shows consistent results with the experiments. This surface morphology variation by solid-phase ionic diffusion serves to provide a fourth mechanism that supplements the traditionally acknowledged solid morphology variation or, in general, porosity variation mechanisms in gas-solid reactions.

Characterization of some biological specimens using TEM and SEM

NASA Astrophysics Data System (ADS)

Ghosh, Nabarun; Smith, Don W.

2009-05-01

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

Characterization of N-doped polycrystalline diamond films deposited on microgrinding tools

NASA Astrophysics Data System (ADS)

Jackson, M. J.; Ahmed, W.

2005-10-01

Chemical vapor deposited diamond films have many industrial applications but are assuming increasing importance in the area of microengineering, most notably in the development of diamond coated microgrinding tools. For these applications the control of structure and morphology is of critical importance. The crystallite size, orientation, surface roughness, and the degree of sp 3 character have a profound effect on the tribological properties of the films deposited. In this article, we present experimental results on the effects of nitrogen doping on the surface morphology, crystallite size, and wear of microgrinding tools. The sp 3 character optimizes at 200 ppm nitrogen, and above this value the surface becomes much smoother and crystal sizes decrease considerably. Fracture-induced wear of the diamond grain is the most important mechanism of material removal from a microgrinding tool during the grinding process. Fracture occurs as a consequence of tensile stresses induced into diamond grains by grinding forces to which they are subjected. The relationship between the wear of diamond coated grinding tools, component grinding forces, and induced stresses in the model diamond grains is described in detail. A significant correlation was found between the maximum value of tensile stress induced in the diamond grain and the appropriate wheel-wear parameter (grinding ratio). It was concluded that the magnitude of tensile stresses induced in the diamond grain by grinding forces at the rake face is the best indicator of tool wear during the grinding process.

Quantitative Classification of Rice (Oryza sativa L.) Root Length and Diameter Using Image Analysis.

PubMed

Gu, Dongxiang; Zhen, Fengxian; Hannaway, David B; Zhu, Yan; Liu, Leilei; Cao, Weixing; Tang, Liang

2017-01-01

Quantitative study of root morphological characteristics of plants is helpful for understanding the relationships between their morphology and function. However, few studies and little detailed and accurate information of root characteristics were reported in fine-rooted plants like rice (Oryza sativa L.). The aims of this study were to quantitatively classify fine lateral roots (FLRs), thick lateral roots (TLRs), and nodal roots (NRs) and analyze their dynamics of mean diameter (MD), lengths and surface area percentage with growth stages in rice plant. Pot experiments were carried out during three years with three rice cultivars, three nitrogen (N) rates and three water regimes. In cultivar experiment, among the three cultivars, root length of 'Yangdao 6' was longest, while the MD of its FLR was the smallest, and the mean diameters for TLR and NR were the largest, the surface area percentage (SAP) of TLRs (SAPT) was the highest, indicating that Yangdao 6 has better nitrogen and water uptake ability. High N rate increased the length of different types of roots and increased the MD of lateral roots, decreased the SAP of FLRs (SAPF) and TLRs, but increased the SAP of NRs (SAPN). Moderate decrease of water supply increased root length and diameter, water stress increased the SAPF and SAPT, but decreased SAPN. The quantitative results indicate that rice plant tends to increase lateral roots to get more surface area for nitrogen and water uptake when available assimilates are limiting under nitrogen and water stress environments.

Superhydrophobic Ag decorated ZnO nanostructured thin film as effective surface enhanced Raman scattering substrates

NASA Astrophysics Data System (ADS)

Jayram, Naidu Dhanpal; Sonia, S.; Poongodi, S.; Kumar, P. Suresh; Masuda, Yoshitake; Mangalaraj, D.; Ponpandian, N.; Viswanathan, C.

2015-11-01

The present work is an attempt to overcome the challenges in the fabrication of super hydrophobic silver decorated zinc oxide (ZnO) nanostructure thin films via thermal evaporation process. The ZnO nanowire thin films are prepared without any surface modification and show super hydrophobic nature with a contact angle of 163°. Silver is further deposited onto the ZnO nanowire to obtain nanoworm morphology. Silver decorated ZnO (Ag@ZnO) thin films are used as substrates for surface enhanced Raman spectroscopy (SERS) studies. The formation of randomly arranged nanowire and silver decorated nanoworm structure is confirmed using FESEM, HR-TEM and AFM analysis. Crystallinity and existence of Ag on ZnO are confirmed using XRD and XPS studies. A detailed growth mechanism is discussed for the formation of the nanowires from nanobeads based on various deposition times. The prepared SERS substrate reveals a reproducible enhancement of 3.082 × 107 M for Rhodamine 6G dye (R6G) for 10-10 molar concentration per liter. A higher order of SERS spectra is obtained for a contact angle of 155°. Thus the obtained thin films show the superhydrophobic nature with a highly enhanced Raman spectrum and act as SERS substrates. The present nanoworm morphology shows a new pathway for the construction of semiconductor thin films for plasmonic studies and challenges the orderly arranged ZnO nanorods, wires and other nano structure substrates used in SERS studies.

Quantitative Classification of Rice (Oryza sativa L.) Root Length and Diameter Using Image Analysis

PubMed Central

Gu, Dongxiang; Zhen, Fengxian; Hannaway, David B.; Zhu, Yan; Liu, Leilei; Cao, Weixing; Tang, Liang

2017-01-01

Quantitative study of root morphological characteristics of plants is helpful for understanding the relationships between their morphology and function. However, few studies and little detailed and accurate information of root characteristics were reported in fine-rooted plants like rice (Oryza sativa L.). The aims of this study were to quantitatively classify fine lateral roots (FLRs), thick lateral roots (TLRs), and nodal roots (NRs) and analyze their dynamics of mean diameter (MD), lengths and surface area percentage with growth stages in rice plant. Pot experiments were carried out during three years with three rice cultivars, three nitrogen (N) rates and three water regimes. In cultivar experiment, among the three cultivars, root length of ‘Yangdao 6’ was longest, while the MD of its FLR was the smallest, and the mean diameters for TLR and NR were the largest, the surface area percentage (SAP) of TLRs (SAPT) was the highest, indicating that Yangdao 6 has better nitrogen and water uptake ability. High N rate increased the length of different types of roots and increased the MD of lateral roots, decreased the SAP of FLRs (SAPF) and TLRs, but increased the SAP of NRs (SAPN). Moderate decrease of water supply increased root length and diameter, water stress increased the SAPF and SAPT, but decreased SAPN. The quantitative results indicate that rice plant tends to increase lateral roots to get more surface area for nitrogen and water uptake when available assimilates are limiting under nitrogen and water stress environments. PMID:28103264

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.

Fusion of Remote Sensing Methods, UAV Photogrammetry and LiDAR Scanning products for monitoring fluvial dynamics

NASA Astrophysics Data System (ADS)

Lendzioch, Theodora; Langhammer, Jakub; Hartvich, Filip

2015-04-01

Fusion of remote sensing data is a common and rapidly developing discipline, which combines data from multiple sources with different spatial and spectral resolution, from satellite sensors, aircraft and ground platforms. Fusion data contains more detailed information than each of the source and enhances the interpretation performance and accuracy of the source data and produces a high-quality visualisation of the final data. Especially, in fluvial geomorphology it is essential to get valuable images in sub-meter resolution to obtain high quality 2D and 3D information for a detailed identification, extraction and description of channel features of different river regimes and to perform a rapid mapping of changes in river topography. In order to design, test and evaluate a new approach for detection of river morphology, we combine different research techniques from remote sensing products to drone-based photogrammetry and LiDAR products (aerial LiDAR Scanner and TLS). Topographic information (e.g. changes in river channel morphology, surface roughness, evaluation of floodplain inundation, mapping gravel bars and slope characteristics) will be extracted either from one single layer or from combined layers in accordance to detect fluvial topographic changes before and after flood events. Besides statistical approaches for predictive geomorphological mapping and the determination of errors and uncertainties of the data, we will also provide 3D modelling of small fluvial features.

Morphological comparison of five species of poison dart frogs of the genus Ranitomeya (Anura: Dendrobatidae) including the skeleton, the muscle system and inner organs.

PubMed

Krings, Markus; Klein, Benjamin; Heneka, Markus J; Rödder, Dennis

2017-01-01

The morphology of larvae stages of most amphibians are often completely different than in adults. Tadpole descriptions have historically been based on external characters like morphometrics, color pattern and oral disc structure. Other papers described anatomical details by the use of dissections. The increase in micro-CT scanning technology provides an opportunity to quantify and describe in detail internal characters like skeleton, musculature and organs. To date, no such tadpole descriptions exist for the well-studied Neotropical poison dart frog genus Ranitomeya (Anura: Dendrobatidae). Here we provide descriptions of the internal skeletal, musculature and organ structures of five Ranitomeya species and then provide morphological comparisons. Contrary to previous observations, closely related species display several morphological differences. For example, we observed considerable variation in chondrocranial characters, the extent of cranial ossifications, the appearance of some cranial muscles and the arrangement of inner organs. Further studies on the tadpole morphology of more species of Ranitomeya and other dendrobatid genera are needed to enable us to understand the complete morphological variation in this group.

Morphological comparison of five species of poison dart frogs of the genus Ranitomeya (Anura: Dendrobatidae) including the skeleton, the muscle system and inner organs

PubMed Central

Krings, Markus; Klein, Benjamin; Heneka, Markus J.

2017-01-01

The morphology of larvae stages of most amphibians are often completely different than in adults. Tadpole descriptions have historically been based on external characters like morphometrics, color pattern and oral disc structure. Other papers described anatomical details by the use of dissections. The increase in micro-CT scanning technology provides an opportunity to quantify and describe in detail internal characters like skeleton, musculature and organs. To date, no such tadpole descriptions exist for the well-studied Neotropical poison dart frog genus Ranitomeya (Anura: Dendrobatidae). Here we provide descriptions of the internal skeletal, musculature and organ structures of five Ranitomeya species and then provide morphological comparisons. Contrary to previous observations, closely related species display several morphological differences. For example, we observed considerable variation in chondrocranial characters, the extent of cranial ossifications, the appearance of some cranial muscles and the arrangement of inner organs. Further studies on the tadpole morphology of more species of Ranitomeya and other dendrobatid genera are needed to enable us to understand the complete morphological variation in this group. PMID:28235032

Structural assessment and multi-parameter monitoring - an application to the Salcher landslide (Austria)

NASA Astrophysics Data System (ADS)

Engels, Alexander; Canli, Ekrem; Thiebes, Benni; Glade, Thomas

2015-04-01

Landslides pose a serious threat to many communities in Austria. The region of Lower Austria is underlayed, amongst others, by the lithological units of the Flysch Zone and the Gresten Klippenbelt. Both are particularly affected by landslides and the majority of episodic occurrences are bound to these two units. The active Salcher landslide is situated at the western border of the municipality of Gresten and is embedded in the geologic transition zone of the respective lithological units. The landslide is a reactivated and deep seated complex landslide that endangers buildings, parts of a road and lifelines such as power and optical fiber lines, fresh and sewage water supplies. Its varying movement rates are in the order of a few centimeters per year and consequently are classified as slow to extremely slow. Despite biannual geodetic surveys, little is known about the dynamic behavior including the triggering and controlling factors and its internal structure. Surface and subsurface investigations were therefore carried out on that landslide. With the intention to detect morphological surface changes, comparative geomorphologic mapping and terrestrial laser scanning was performed. Additionally, surface kinematical information was acquired by historical documents and GNSS measurements. The detailed present soil-physical conditions and their relation to current dynamics were investigated by six drill cores and three inclinometer installations. Soil specimens were obtained by percussion drilling. Particle size distribution, and water and carbonate content were subsequently analyzed in the laboratory. In addition, dynamic probing was performed at 13 sites across the landslide body and resistance values were compared to textural findings. The soil specimens show a heterogeneous texture and large variations in carbonate and water content. Soil wedges, originating from local displacements, were determined in two drill cores. Very high water content and resulting plastic behavior indicate the presence of weakness zones with the geometry of a translational landslide. The depths of the drill cores ranged from 5 m to 9 m. The sampling density of each respective core was less than one meter. The final depth of the three inclinometers ranged from 6.5 m to 13 m. The inclinometers were placed at prominent morphological landslide features like the head, bulged levee and the transitions zone and were maintained over the past eight months. Subsurface displacement measurements were then compared with the soils' texture. GNSS based geomorphological mapping revealed areas that underwent morphological changes. Surface displacements were analyzed by terrestrial laserscanning. These sites investigations are the basis for a detailed understanding of the landslide dynamics. In the future, the measurements will be applied in modelling concepts which will be embedded in a comprehensive landslide early warning system.

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.

Phenotypic and Physiological Characterization of the Epibiotic Interaction Between TM7x and Its Basibiont Actinomyces.

PubMed

Bor, Batbileg; Poweleit, Nicole; Bois, Justin S; Cen, Lujia; Bedree, Joseph K; Zhou, Z Hong; Gunsalus, Robert P; Lux, Renate; McLean, Jeffrey S; He, Xuesong; Shi, Wenyuan

2016-01-01

Despite many examples of obligate epibiotic symbiosis (one organism living on the surface of another) in nature, such an interaction has rarely been observed between two bacteria. Here, we further characterize a newly reported interaction between a human oral obligate parasitic bacterium TM7x (cultivated member of Candidatus Saccharimonas formerly Candidate Phylum TM7), and its basibiont Actinomyces odontolyticus species (XH001), providing a model system to study epiparasitic symbiosis in the domain Bacteria. Detailed microscopic studies indicate that both partners display extensive morphological changes during symbiotic growth. XH001 cells manifested as short rods in monoculture, but displayed elongated and hyphal morphology when physically associated with TM7x. Interestingly, these dramatic morphological changes in XH001 were also induced in oxygen-depleted conditions, even in the absence of TM7x. Targeted quantitative real-time PCR (qRT-PCR) analyses revealed that both the physical association with TM7x as well as oxygen depletion triggered up-regulation of key stress response genes in XH001, and in combination, these conditions act in an additive manner. TM7x and XH001 co-exist with relatively uniform cell morphologies under nutrient-replete conditions. However, upon nutrient depletion, TM7x-associated XH001 displayed a variety of cell morphologies, including swollen cell body, clubbed-ends, and even cell lysis, and a large portion of TM7x cells transformed from ultrasmall cocci into elongated cells. Our study demonstrates a highly dynamic interaction between epibiont TM7x and its basibiont XH001 in response to physical association or environmental cues such as oxygen level and nutritional status, as reflected by their morphological and physiological changes during symbiotic growth.

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.

BlastNeuron for Automated Comparison, Retrieval and Clustering of 3D Neuron Morphologies.

PubMed

Wan, Yinan; Long, Fuhui; Qu, Lei; Xiao, Hang; Hawrylycz, Michael; Myers, Eugene W; Peng, Hanchuan

2015-10-01

Characterizing the identity and types of neurons in the brain, as well as their associated function, requires a means of quantifying and comparing 3D neuron morphology. Presently, neuron comparison methods are based on statistics from neuronal morphology such as size and number of branches, which are not fully suitable for detecting local similarities and differences in the detailed structure. We developed BlastNeuron to compare neurons in terms of their global appearance, detailed arborization patterns, and topological similarity. BlastNeuron first compares and clusters 3D neuron reconstructions based on global morphology features and moment invariants, independent of their orientations, sizes, level of reconstruction and other variations. Subsequently, BlastNeuron performs local alignment between any pair of retrieved neurons via a tree-topology driven dynamic programming method. A 3D correspondence map can thus be generated at the resolution of single reconstruction nodes. We applied BlastNeuron to three datasets: (1) 10,000+ neuron reconstructions from a public morphology database, (2) 681 newly and manually reconstructed neurons, and (3) neurons reconstructions produced using several independent reconstruction methods. Our approach was able to accurately and efficiently retrieve morphologically and functionally similar neuron structures from large morphology database, identify the local common structures, and find clusters of neurons that share similarities in both morphology and molecular profiles.

The RSA survey of dwarf galaxies, 1: Optical photometry

NASA Technical Reports Server (NTRS)

Vader, J. Patricia; Chaboyer, Brian

1994-01-01

We present detailed surface photometry, based on broad B-band charge coupled device (CCD) images, of about 80 dwarf galaxies. Our sample represents approximately 10% of all dwarf galaxies identified in the vicinity of Revised Shapley-Ames (RSA) galaxies on high resolution blue photographic plates, referred to as the RSA survey of dwarf galaxies. We derive global properties and radial surface brightness profiles, and examine the morphologies. The radial surface brightness profiles of dwarf galaxies, whether early or late type, display the same varieties in shape and complexity as those of classical giant galaxies. Only a few are well described by a pure r(exp 1/4) law. Exponential profiles prevail. Features typical of giant disk galaxies, such as exponential profiles with a central depression, lenses, and even, in one case (IC 2041), a relatively prominent bulge are also found in dwarf galaxies. Our data suggest that the central region evolves from being bulge-like, with an r(exp 1/4) law profile, in bright galaxies to a lens-like structure in dwarf galaxies. We prove detailed surface photometry to be a helpful if not always sufficient tool in investigating the structure of dwarf galaxies. In many cases kinematic information is needed to complete the picture. We find the shapes of the surface brightness profiles to be loosely associated with morphological type. Our sample contains several new galaxies with properties intermediate between those of giant and dwarf ellipticals (but no M32-like objects). This shows that such intermediate galaxies exist so that at least a fraction of early-type dwarf ellipticals is structurally related to early-type giants instead of belonging to a totally unrelated, disjunct family. This supports an origin of early-type dwarf galaxies as originally more massive systems that acquired their current morphology as a result of substantial, presumable supernova-driven, mass loss. On the other hand, several early-type dwarfs in our sample are merger candidates. Merger events may lead to anisotropic velocity distributions in systems of any luminosity, including dwarfs. The RSA sample of dwarf galaxies is more likely to contain mergers because, in contrast to earlier dwarf galaxy surveys that have focused on clusters and rich groups of galaxies, the RSA dwarfs are typically located in low density environments. The occurrence of mergers among dwarf galaxies is of interest in connection with the rapid evolution of faint blue galaxy counts at redshift z less than 1 which suggests that dwarf galaxies were about five times more numerous in the recent past. Finally, our sample contains several examples of late-type dwarfs and 'transition' types that are potential precursors of nucleated early-type dwarfs. All the above processes--mass loss, mergers, astration--are likely to have contributed to the formation of the current population of diffuse early-type dwarfs. A few new redshifts of dwarf galaxies are reported in this paper.

Solution processed deposition of electron transport layers on perovskite crystal surface-A modeling based study

NASA Astrophysics Data System (ADS)

Mortuza, S. M.; Taufique, M. F. N.; Banerjee, Soumik

2017-02-01

The power conversion efficiency (PCE) of planar perovskite solar cells (PSCs) has reached up to ∼20%. However, structural and chemicals defects that lead to hysteresis in the perovskite based thin film pose challenges. Recent work has shown that thin films of [6,6]-phenyl-C61-butyric acid methyl ester (PCBM) deposited on the photo absorption layer, using solution processing techniques, minimize surface pin holes and defects thereby increasing the PCE. We developed and employed a multiscale model based on molecular dynamics (MD) and kinetic Monte Carlo (kMC) to establish a relationship between deposition rate and surface coverage on perovskite surface. The MD simulations of PCBMs dispersed in chlorobenzene, sandwiched between (110) perovskite substrates, indicate that PCBMs are deposited through anchoring of the oxygen atom of carbonyl group to the exposed lead (Pb) atom of (110) perovskite surface. Based on rates of distinct deposition events calculated from MD, kMC simulations were run to determine surface coverage at much larger time and length scales than accessible by MD alone. Based on the model, a generic relationship is established between deposition rate of PCBMs and surface coverage on perovskite crystal. The study also provides detailed insights into the morphology of the deposited film.

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.

Extremely pulsatile flow around a surface-mounted hemisphere: synergistic experiments and simulations

NASA Astrophysics Data System (ADS)

Carr, Ian A.; Beratlis, Nikolaos; Balaras, Elias; Plesniak, Michael W.

2017-11-01

Extremely pulsatile flow (where the amplitude of oscillation pulsation is of the same order as the mean flow) over a three-dimensional, surface-mounted bluff body gives rise a wealth of fluid dynamics phenomena. In this study, we extend our previous experimental work on extremely pulsatile flow around a surface-mounted hemisphere by performing a complementary direct numerical simulation. Results from the experiment and simulation will be presented and compared. After establishing the agreement between experiment and simulation, we will examine the morphology and dynamics of the vortex structures in the wake of the hemisphere, and the effects of extreme pulsatility. The dynamics of the arch-type recirculation vortex is of primary interest, in particular its upstream propagation due to self-induced velocity in the direction opposite to the freestream during deceleration. In addition to the velocity field, the surface pressure field throughout the pulsatile cycle will be presented. These synergistic experiments and simulations provide a detailed view into the complex flow fields associated with pulsatile flow over a surface-mounted hemisphere. This material is based upon work supported by the National Science Foundation under Grant Number CBET-1236351 and the GW Center for Biomimetics and Bioinspired Engineering.

Heritability maps of human face morphology through large-scale automated three-dimensional phenotyping

NASA Astrophysics Data System (ADS)

Tsagkrasoulis, Dimosthenis; Hysi, Pirro; Spector, Tim; Montana, Giovanni

2017-04-01

The human face is a complex trait under strong genetic control, as evidenced by the striking visual similarity between twins. Nevertheless, heritability estimates of facial traits have often been surprisingly low or difficult to replicate. Furthermore, the construction of facial phenotypes that correspond to naturally perceived facial features remains largely a mystery. We present here a large-scale heritability study of face geometry that aims to address these issues. High-resolution, three-dimensional facial models have been acquired on a cohort of 952 twins recruited from the TwinsUK registry, and processed through a novel landmarking workflow, GESSA (Geodesic Ensemble Surface Sampling Algorithm). The algorithm places thousands of landmarks throughout the facial surface and automatically establishes point-wise correspondence across faces. These landmarks enabled us to intuitively characterize facial geometry at a fine level of detail through curvature measurements, yielding accurate heritability maps of the human face (www.heritabilitymaps.info).

Which Triggers Produce the Most Erosive, Frequent, and Longest Runout Turbidity Currents on Deltas?

NASA Astrophysics Data System (ADS)

Hizzett, J. L.; Hughes Clarke, J. E.; Sumner, E. J.; Cartigny, M. J. B.; Talling, P. J.; Clare, M. A.

2018-01-01

Subaerial rivers and turbidity currents are the two most voluminous sediment transport processes on our planet, and it is important to understand how they are linked offshore from river mouths. Previously, it was thought that slope failures or direct plunging of river floodwater (hyperpycnal flow) dominated the triggering of turbidity currents on delta fronts. Here we reanalyze the most detailed time-lapse monitoring yet of a submerged delta; comprising 93 surveys of the Squamish Delta in British Columbia, Canada. We show that most turbidity currents are triggered by settling of sediment from dilute surface river plumes, rather than landslides or hyperpycnal flows. Turbidity currents triggered by settling plumes occur frequently, run out as far as landslide-triggered events, and cause the greatest changes to delta and lobe morphology. For the first time, we show that settling from surface plumes can dominate the triggering of hazardous submarine flows and offshore sediment fluxes.

Nanofilms of hyaluronan/chitosan assembled layer-by-layer: An antibacterial surface for Xylella fastidiosa.

PubMed

Hernández-Montelongo, Jacobo; Nascimento, Vicente F; Murillo, Duber; Taketa, Thiago B; Sahoo, Prasana; de Souza, Alessandra A; Beppu, Marisa M; Cotta, Monica A

2016-01-20

In this work, nanofilms of hyaluronan/chitosan (HA/CHI) assembled layer by layer were synthesized; their application as a potential antimicrobial material was demonstrated for the phytopathogen Xylella fastidiosa, a gram-negative bacterium, here used as a model. For the synthesis, the influence of pH and ionic strength of these natural polymer stem-solutions on final characteristics of the HA/CHI nanofilms was studied in detail. The antibacterial effect was evaluated using widefield fluorescence microscopy. These results were correlated with the chemical properties of the nanofilms, studied by FTIR and Raman spectroscopy, as well as with their morphology and surface properties characterized using SEM and AFM. The present findings can be extended to design and optimize HA/CHI nanofilms with enhanced antimicrobial behavior for other type of phytopathogenic gram-negative bacteria species, such as Xanthomonas citri, Xanthomas campestri and Ralstonia solanacearum. Copyright © 2015 Elsevier Ltd. All rights reserved.

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.

Geometric Accuracy Analysis of Worlddem in Relation to AW3D30, Srtm and Aster GDEM2

NASA Astrophysics Data System (ADS)

Bayburt, S.; Kurtak, A. B.; Büyüksalih, G.; Jacobsen, K.

2017-05-01

In a project area close to Istanbul the quality of WorldDEM, AW3D30, SRTM DSM and ASTER GDEM2 have been analyzed in relation to a reference aerial LiDAR DEM and to each other. The random and the systematic height errors have been separated. The absolute offset for all height models in X, Y and Z is within the expectation. The shifts have been respected in advance for a satisfying estimation of the random error component. All height models are influenced by some tilts, different in size. In addition systematic deformations can be seen not influencing the standard deviation too much. The delivery of WorldDEM includes information about the height error map which is based on the interferometric phase errors, and the number and location of coverage's from different orbits. A dependency of the height accuracy from the height error map information and the number of coverage's can be seen, but it is smaller as expected. WorldDEM is more accurate as the other investigated height models and with 10 m point spacing it includes more morphologic details, visible at contour lines. The morphologic details are close to the details based on the LiDAR digital surface model (DSM). As usual a dependency of the accuracy from the terrain slope can be seen. In forest areas the canopy definition of InSAR X- and C-band height models as well as for the height models based on optical satellite images is not the same as the height definition by LiDAR. In addition the interferometric phase uncertainty over forest areas is larger. Both effects lead to lower height accuracy in forest areas, also visible in the height error map.

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.

Morphology of Wrinkle Ridges on Lunae and Solis Plana, Mars from MOLA Topography: Implications for Their Kinematic Development

NASA Technical Reports Server (NTRS)

Tate, A.; Golombek, M. P.; Mueller, K. J.

2001-01-01

Mars Orbiter Laser Altimeter (MOLA) topography is used to define the detailed morphology and kinematic development of martian wrinkle ridges on Lunae and Solis Plana. Changes in ridge morphology suggest they form as fault-propagation folds, often with significant backthrusts. Additional information is contained in the original extended abstract.

Sn-doped ZnO nanopetal networks for efficient photocatalytic degradation of dye and gas sensing applications

NASA Astrophysics Data System (ADS)

Bhatia, Sonik; Verma, Neha; Bedi, R. K.

2017-06-01

Nowadays, tremendous increase in environmental issue is an alarming threat to the ecosystem. This paper reports, rapid synthesis and characterization for tin doped ZnO nanoparticles prepared by simple combustion method and doctor blade technique. The prepared nanoparticles were characterized by several techniques in terms of their morphological, structural, compositional, optical, photocatalytic and gas sensing properties. These detailed characterization confirmed that all the synthesized nanoparticles are well crystalline and having good optoelectronic properties. Herein, different concentrations of Sn (0.5 at. wt%, 1.0 at. wt%, 2.0 at. wt%, 3.0 at. wt%) were used as dopants (SZ1-SZ4). The morphology of synthesized technique confirmed that the petal-shaped nanoparticles has high surface area and are well crystalline. In order to develop smart and functional nano-device, the prepared powder was coated on glass substrate by doctor blade technique and fabricated device was sensed for ethanol and acetone gas at different operating temperatures (300-500̊C). It is noteworthy that morphology of the nanoparticles of the sensitive layer is maintained after different concentration of Sn. High sensitivity is the main cause of high surface area and tin doping. PL intensity near 598 nm of SZ3 is greater than other Sn-doped ZnO which indicates more oxygen vacancies of SZ3 is responsible for enhanced gas sensitivity and photocatalytic activity. The sensing performance showed 5% volume of ethanol and acetone and gases could be detected with sensitivity of 86.80% and 84.40% respectively. The mechanism for the improvement in the sensing properties can be explained with the surface adsorption theory. Sn-ZnO was used as photocatalyst for degradation of DR-31 dye. Optimum concentration of prepared nanoparticles (2.0 at. wt%) exhibits complete degradation of dye only in 60 min under UV irradiation.

Comparative analysis of Trichuris muris surface using conventional, low vacuum, environmental and field emission scanning electron microscopy.

PubMed

Lopes Torres, Eduardo José; de Souza, Wanderley; Miranda, Kildare

2013-09-23

The whipworm of the genus Trichuris Roederer, 1791, is a nematode of worldwide distribution and comprises species that parasitize humans and other mammals. Infections caused by Trichuris spp. in mammals can lead to various intestinal diseases of human and veterinary interest. The morphology of Trichuris spp. and other helminths has been mostly studied using conventional scanning electron microscopy of chemically fixed, dried and metal-coated specimens, although this kind of preparation has been shown to introduce a variety of artifacts such as sample shrinking, loss of secreted products and/or hiding of small structures due to sample coating. Low vacuum (LVSEM) and environmental scanning electron microscopy (ESEM) have been applied to a variety of insulator samples, also used in the visualization of hydrated and/or live specimens in their native state. In the present work, we used LVSEM and ESEM to analyze the surface of T. muris and analyze its interaction with the host tissue using freshly fixed or unfixed hydrated samples. Analysis of hydrated samples showed a set of new features on the surface of the parasite and the host tissue, including the presence of the secretory products of the bacillary glands on the surface of the parasite, and the presence of mucous material and eggs on the intestinal surface. Field emission scanning electron microscopy (FESEM) was also applied to reveal the detailed structure of the glandular chambers in fixed, dried and metal coated samples. Taken together, the results show that analysis of hydrated samples may provide new insights in the structural organization of the surface of helminth parasites and its interaction with the infected tissue, suggesting that the application of alternative SEM techniques may open new perspectives for analysis in taxonomy, morphology and host-parasite interaction fields. Copyright © 2013 Elsevier B.V. All rights reserved.

Influence of substrate material and surface finishing on the morphology of the calcium-phosphate coating.

PubMed

Leitão, E; Barbosa, M A; de Groot, K

1997-07-01

The formation of an apatite-like layer was achieved by immersing Ti-6A1-4V, Ti-Al-2.5Fe, and 316 L stainless-steel substrata in Hank's balanced salt solution (HBSS). The layer was characterized by surface analysis techniques, namely X-ray microanalysis and X-ray diffraction, and the morphology was observed by scanning electron microscopy and atomic force microscopy. The concentrations of Ca and P were monitored as a function of time. The morphology of the precipitate layer seems to be dependent both on the type of metal substrate and its surface finish. Polished Ti-6A1-4V and Ti-Al-2.5Fe surfaces exhibit a plate precipitate morphology, whereas rougher surfaces show scattered crystal-like precipitation. The results suggest that the layer produced by immersion of polished titanium alloys in HBSS is constituted by an amorphous apatite.

Surface effects of vapour-liquid-solid driven Bi surface droplets formed during molecular-beam-epitaxy of GaAsBi

PubMed Central

Steele, J. A.; Lewis, R. A.; Horvat, J.; Nancarrow, M. J. B.; Henini, M.; Fan, D.; Mazur, Y. I.; Schmidbauer, M.; Ware, M. E.; Yu, S.-Q.; Salamo, G. J.

2016-01-01

Herein we investigate a (001)-oriented GaAs1−xBix/GaAs structure possessing Bi surface droplets capable of catalysing the formation of nanostructures during Bi-rich growth, through the vapour-liquid-solid mechanism. Specifically, self-aligned “nanotracks” are found to exist trailing the Bi droplets on the sample surface. Through cross-sectional high-resolution transmission electron microscopy the nanotracks are revealed to in fact be elevated above surface by the formation of a subsurface planar nanowire, a structure initiated mid-way through the molecular-beam-epitaxy growth and embedded into the epilayer, via epitaxial overgrowth. Electron microscopy studies also yield the morphological, structural, and chemical properties of the nanostructures. Through a combination of Bi determination methods the compositional profile of the film is shown to be graded and inhomogeneous. Furthermore, the coherent and pure zincblende phase property of the film is detailed. Optical characterisation of features on the sample surface is carried out using polarised micro-Raman and micro-photoluminescence spectroscopies. The important light producing properties of the surface nanostructures are investigated through pump intensity-dependent micro-PL measurements, whereby relatively large local inhomogeneities are revealed to exist on the epitaxial surface for important optical parameters. We conclude that such surface effects must be considered when designing and fabricating optical devices based on GaAsBi alloys. PMID:27377213

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 of a submerged insular shelves in the West Alboran Basin.

NASA Astrophysics Data System (ADS)

Lafosse, Manfred; Le Roy, Pascal; Gorini, Christian; Rabineau, Marina; d'Acremont, Elia; Rabaute, Alain

2017-04-01

The dynamic of the seafloor in the Western Mediterranean Sea reflects the variety of the natural processes shaping it. Each of the sub-surface features is the result of tectonic, sedimentary and oceanic processes and eustatic sea-level variations. This study is focused on the morphology of three flat bathymetric highs and on the continental shelf in the Alboran Sea that show a variety of detailed seabed features that we attribute to a combination of present-day Mediterranean water mass flows, Quaternary active folding and faulting, differential erosion linked to relative-sea-level variation and local hydrodynamic. Swath bathymetry and reflectivity data, 2D seismic lines of multiple resolutions (12 channels, SPARKER source, and TOPAS seismic lines) have been acquired during three successive cruises: the MARLBORO-1 (2011), the MARLBORO-2 (2012) and the SARAS (2012) surveys. Our study deciphers the seabed structure of the banks with morphometric measurements (slope gradient, plan curvature, and topographic index) and correlates these structures to the stratigraphy of surrounding shelf. We show that the competition between active folding of the Miocene units and the erosion linked to the late Quaternary lowstands is creates the topography of the banks. The elevations of the flat surfaces measured on the banks are close to -110m and -80m. They are interpreted as submerged depositional surfaces linked to glacial and post-glacial deposit and wave-ravinement erosional surfaces as observed in other Mediterranean continental shelves. The analysis of the altitudinal spacing of these marine terraces indicates a spatial pattern with varying uplift rates. Furthermore, the characterization of sub-aqueous dune patterns locally linked to potential cold carbonate seamount could reflect the influence of water-masses current on the stratigraphic organization.

Bedrock mapping of buried valley networks using seismic reflection and airborne electromagnetic data

NASA Astrophysics Data System (ADS)

Oldenborger, G. A.; Logan, C. E.; Hinton, M. J.; Pugin, A. J.-M.; Sapia, V.; Sharpe, D. R.; Russell, H. A. J.

2016-05-01

In glaciated terrain, buried valleys often host aquifers that are significant groundwater resources. However, given the range of scales, spatial complexity and depth of burial, buried valleys often remain undetected or insufficiently mapped. Accurate and thorough mapping of bedrock topography is a crucial step in detecting and delineating buried valleys and understanding formative valley processes. We develop a bedrock mapping procedure supported by the combination of seismic reflection data and helicopter time-domain electromagnetic data with water well records for the Spiritwood buried valley aquifer system in Manitoba, Canada. The limited spatial density of water well bedrock observations precludes complete depiction of the buried valley bedrock topography and renders the water well records alone inadequate for accurate hydrogeological model building. Instead, we leverage the complementary strengths of seismic reflection and airborne electromagnetic data for accurate local detection of the sediment-bedrock interface and for spatially extensive coverage, respectively. Seismic reflection data are used to define buried valley morphology in cross-section beneath survey lines distributed over a regional area. A 3D model of electrical conductivity is derived from inversion of the airborne electromagnetic data and used to extrapolate buried valley morphology over the entire survey area. A spatially variable assignment of the electrical conductivity at the bedrock surface is applied to different features of the buried valley morphology identified in the seismic cross-sections. Electrical conductivity is then used to guide construction of buried valley shapes between seismic sections. The 3D locus of points defining each morphological valley feature is constructed using a path optimization routine that utilizes deviation from the assigned electrical conductivities as the cost function. Our resulting map represents a bedrock surface of unprecedented detail with more complexity than has been suggested by previous investigations. Our procedure is largely data-driven with an adaptable degree of expert user input that provides a clear protocol for incorporating different types of geophysical data into the bedrock mapping procedure.

Quantification of texture match of the skin graft: function and morphology of the stratum corneum.

PubMed

Inoue, K; Matsumoto, K

1986-01-01

In an attempt to analyze the "texture match" of grafted skin, functional and morphological aspects of the stratum corneum were studied using the Skin Surface Hydrometer (IBS Inc.) and the scanning electron microscope. The results showed that hygroscopicity and water holding capacity of the stratum corneum played a crucial role in making the skin surface soft and smooth. Morphologically there were regional differences in the surface pattern and the mean area of corneocytes, suggesting that these differences affect skin texture. It is suggested that the present functional and morphological studies of the stratum corneum can provide a quantitative measure of the "texture match".

Interfacial Interaction in Anodic Aluminum Oxide Templates Modifies Morphology, Surface Area, and Crystallization of Polyamide-6 Nanofibers.

PubMed

Xue, Junhui; Xu, Yizhuang; Jin, Zhaoxia

2016-03-08

Here, we demonstrated that, when the precipitation process of polyamide-6 (PA6) solution happens in cylindrical channels of an anodized aluminum oxide membrane (AAO), interface interactions between a solid surface, solvent, non-solvent, and PA6 will influence the obtained polymer nanostructures, resulting in complex morphologies, increased surface area, and crystallization changes. With the enhancing interaction of PA6 and the AAO surface, the morphology of PA6 nanostructures changes from solid nanofibers, mesoporous, to bamboo-like, while at the same time, metastable γ-phase domains increase in these PA6 nanostructures. Brunauer-Emmett-Teller (BET) surface areas of solid, bamboo-like, and mesoporous PA6 nanofibers rise from 16, 20.9, to 25 m(2)/g. This study shows that interfacial interaction in AAO template fabrication can be used in manipulating the morphology and crystallization of one-dimensional polymer nanostructures. It also provides us a simple and novel method to create porous PA6 nanofibers with a large surface area.

An in situ polymerization approach for the synthesis of superhydrophobic and superoleophilic nanofibrous membranes for oil-water separation

NASA Astrophysics Data System (ADS)

Shang, Yanwei; Si, Yang; Raza, Aikifa; Yang, Liping; Mao, Xue; Ding, Bin; Yu, Jianyong

2012-11-01

Superhydrophobic and superoleophilic nanofibrous membranes exhibiting robust oil-water separation performance were prepared by a facile combination of electrospun cellulose acetate (CA) nanofibers and a novel in situ polymerized fluorinated polybenzoxazine (F-PBZ) functional layer that incorporated silica nanoparticles (SiO2 NPs). By employing the F-PBZ/SiO2 NPs modification, the pristine hydrophilic CA nanofibrous membranes were endowed with a superhydrophobicity with the water contact angle of 161° and a superoleophilicity with the oil contact angle of 3°. Surface morphological studies have indicated that the wettability of resultant membranes could be manipulated by tuning the surface composition as well as the hierarchical structures. The quantitative hierarchical roughness analysis using the N2 adsorption method has confirmed the major contribution of SiO2 NPs on enhancing the porous structure, and a detailed correlation between roughness and solid-liquid interface pinning is proposed. Furthermore, the as-prepared membranes exhibited fast and efficient separation for oil-water mixtures and excellent stability over a wide range of pH conditions, which would make them a good candidate in industrial oil-polluted water treatments and oil spill cleanup, and also provided a new insight into the design and development of functional nanofibrous membranes through F-PBZ modification.Superhydrophobic and superoleophilic nanofibrous membranes exhibiting robust oil-water separation performance were prepared by a facile combination of electrospun cellulose acetate (CA) nanofibers and a novel in situ polymerized fluorinated polybenzoxazine (F-PBZ) functional layer that incorporated silica nanoparticles (SiO2 NPs). By employing the F-PBZ/SiO2 NPs modification, the pristine hydrophilic CA nanofibrous membranes were endowed with a superhydrophobicity with the water contact angle of 161° and a superoleophilicity with the oil contact angle of 3°. Surface morphological studies have indicated that the wettability of resultant membranes could be manipulated by tuning the surface composition as well as the hierarchical structures. The quantitative hierarchical roughness analysis using the N2 adsorption method has confirmed the major contribution of SiO2 NPs on enhancing the porous structure, and a detailed correlation between roughness and solid-liquid interface pinning is proposed. Furthermore, the as-prepared membranes exhibited fast and efficient separation for oil-water mixtures and excellent stability over a wide range of pH conditions, which would make them a good candidate in industrial oil-polluted water treatments and oil spill cleanup, and also provided a new insight into the design and development of functional nanofibrous membranes through F-PBZ modification. Electronic supplementary information (ESI) available: Detailed synthesis and structural confirmation of BAF-tfa, FT-IR results, OCA results and Movie S1. See DOI: 10.1039/c2nr33063f

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

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.

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.

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.

A brackish diatom, Pseudofrustulia lancea gen. et sp. nov. (Bacillariophyceae), from the Pacific coast of Oregon (USA)

USGS Publications Warehouse

Sawai, Yuki; Nagumo, Tamotsu; Nelson, Alan R.

2016-01-01

Light and electron microscope observations show that a brackish diatom taxon should be classified as a new species of a new genus; Pseudofrustulia lancea gen. et sp. nov. We propose separating Pseudofrustulia from other similar genera such as Frickea, Frustulia, Amphipleura, Muelleria, and Envekadea on the basis of its thickened axial ribs, raphe endings, axial costae, morphology of helictoglossa, size of striae on valve surfaces, and areolae on the inner side between its axial ribs and raphe. Girdle bands may be another diagnostic feature for the separation of Pseudofrustulia from related taxa, but more detailed observations using SEM images are required to determine if bands are diagnostic.

Electron microscopic and ion scattering studies of heteroepitaxial tin-doped indium oxide films

NASA Astrophysics Data System (ADS)

Kamei, Masayuki; Shigesato, Yuzo; Takaki, Satoru; Hayashi, Yasuo; Sasaki, Mikio; Haynes, Tony E.

1994-08-01

The microstructure of heteroepitaxial tin-doped indium oxide (ITO) films were studied in detail. The surface morphology of the heteroepitaxial ITO film consisted of square-shaped, in-plane oriented subgrains (˜300 Å) in contrast to that of the polycrystalline film (characteristic grain-subgrain structure). The subgrain boundaries were predominantly formed along the {110} planes in the ITO film and dislocations were observed primarily along the subgrain boundaries. Ion channeling measurements showed the dislocation density of this film to be approximately 3×1010/cm2, and the angular distribution of the ion channeling yield showed that the subgrains are aligned to within better than 0.3° (standard deviation).

Raman and AFM study of gamma irradiated plastic bottle sheets

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

Ali, Yasir; Kumar, Vijay; Dhaliwal, A. S.

2013-02-05

In this investigation, the effects of gamma irradiation on the structural properties of plastic bottle sheet are studied. The Plastic sheets were exposed with 1.25MeV {sup 60}Co gamma rays source at various dose levels within the range from 0-670 kGy. The induced modifications were followed by micro-Raman and atomic force microscopy (AFM). The Raman spectrum shows the decrease in Raman intensity and formation of unsaturated bonds with an increase in the gamma dose. AFM image displays rough surface morphology after irradiation. The detailed Raman analysis of plastic bottle sheets is presented here, and the results are correlated with the AFMmore » observations.« less

Application of morphologic burrow interpretations to discern continental burrow architects: Lungfish or crayfish?

USGS Publications Warehouse

Hasiotis, Stephen T.; Mitchell, Charles E.; Dubiel, Russell R.

1993-01-01

A methodology for trace fossil identification using burrowing signatures is tested by evaluating ancient and modern lungfish and crayfish burrows and comparing them to previously undescribed burrows in a stratigraphic interval thought to contain both lungfish and crayfish burrows. Permian burrows that bear skeletal remains of the lungfish Gnathorhiza, from museum collections, were evaluated to identify unique burrow morphologies that could be used to distinguish lungfish from crayfish burrows when fossil remains are absent. The lungfish burrows were evaluated for details of the burrowing mechanism preserved in the burrow morphologies together forming burrowing signatures and were compared to new burrows in the Chinle Formation of western Colorado to test the methodology of using burrow signatures to identify unknown burrows.Permian lungfish aestivation burrows show simple, nearly vertical, unbranched architectures and relatively smooth surficial morphologies with characteristic quasi‐horizontal striae on the burrow walls and vertical striae on the bulbous terminus. Burrow lengths do not exceed 0.5 m. In contrast, modern and ancient crayfish burrows exhibit simple to highly complex architectures with highly textured surficial morphologies. Burrow lengths may reach 4 to 5 m.Burrow morphologies unlike those identified in Gnathorhiza aestivation burrows were found in four burrow groups from museum collections. Two of these groups exhibit simple architectures and horizontal striae that were greater in sinuosity and magnitude, respectively. One of these burrows contains the remains of Lysoro‐phus, but the burrow surface reveals no reliable surficial characteristics. It is not clear whether Lysorophustruly burrowed or merely occupied a pre‐existing structure. The other two groups exhibit surficial morphologies similar to those found on modern and ancient crayfish burrows and may provide evidence of freshwater crayfish in the Permian.Burrows from the Upper Triassic Chinle Formation in western Colorado exhibit simple to moderately complex architectural morphologies, ranging from predominantly vertical, unbranched, with little or no chamber development to predominantly vertical, few branches, and with minor chamber development. Surficial burrow morphologies are moderate to highly textured. The burrows have scrape marks, scratch marks, mud and lag‐liners, knobby surfaces, pleopod striae, and body impressions.Although no fossil remains of the burrowing organism were found within or associated with the Chinle burrows from western Colorado, the similarity of architectural and surficial burrow morphologies to those in the Chinle of Canyonlands, Utah and to modern crayfish burrows, clearly indicates that the Colorado burrows are the product of burrowing crayfish rather than lungfish. Evaluation of burrowing signatures preserved in the architectural and surficial burrow morphologies is a very useful tool to compare and contrast Chinle burrows from different regions on the Colorado Plateau. Documentation of crayfish burrows in the Chinle of Utah and Colorado strongly suggests that other large‐diameter Chinle burrows elsewhere on the Colorado Plateau and in stratigraphically equivalent units may also be the product of crayfish activity.

Imaging Catalytic Activation of CO 2 on Cu 2O (110): A First-Principles Study

DOE PAGES

Li, Liang; Zhang, Rui; Vinson, John; ...

2018-03-05

Balancing global energy needs against increasing greenhouse gas emissions requires new methods for efficient CO 2 reduction. While photoreduction of CO 2 is a viable approach for fuel generation, the rational design of photocatalysts hinges on precise characterization of the surface catalytic reactions. Cu 2O is a promising next-generation photocatalyst, but the atomic-scale description of the interaction between CO 2 and the Cu 2O surface is largely unknown, and detailed experimental measurements are lacking. In this study, density-functional-theory (DFT) calculations have been performed to identify the Cu 2O (110) surface stoichiometry that favors CO 2 reduction. To facilitate interpretation ofmore » scanning tunneling microscopy (STM) and X-ray absorption near-edge structures (XANES) measurements, which are useful for characterizing catalytic reactions, we present simulations based on DFT-derived surface morphologies with various adsorbate types. STM and XANES simulations were performed using the Tersoff Hamann approximation and Bethe-Salpeter equation (BSE) approach, respectively. The results provide guidance for observation of CO 2 reduction reaction on, and rational surface engineering of, Cu 2O (110). In conclusion, they also demonstrate the effectiveness of computational image and spectroscopy modeling as a predictive tool for surface catalysis characterization.« less

Fractal analysis as a potential tool for surface morphology of thin films

NASA Astrophysics Data System (ADS)

Soumya, S.; Swapna, M. S.; Raj, Vimal; Mahadevan Pillai, V. P.; Sankararaman, S.

2017-12-01

Fractal geometry developed by Mandelbrot has emerged as a potential tool for analyzing complex systems in the diversified fields of science, social science, and technology. Self-similar objects having the same details in different scales are referred to as fractals and are analyzed using the mathematics of non-Euclidean geometry. The present work is an attempt to correlate fractal dimension for surface characterization by Atomic Force Microscopy (AFM). Taking the AFM images of zinc sulphide (ZnS) thin films prepared by pulsed laser deposition (PLD) technique, under different annealing temperatures, the effect of annealing temperature and surface roughness on fractal dimension is studied. The annealing temperature and surface roughness show a strong correlation with fractal dimension. From the regression equation set, the surface roughness at a given annealing temperature can be calculated from the fractal dimension. The AFM images are processed using Photoshop and fractal dimension is calculated by box-counting method. The fractal dimension decreases from 1.986 to 1.633 while the surface roughness increases from 1.110 to 3.427, for a change of annealing temperature 30 ° C to 600 ° C. The images are also analyzed by power spectrum method to find the fractal dimension. The study reveals that the box-counting method gives better results compared to the power spectrum method.

Imaging Catalytic Activation of CO 2 on Cu 2O (110): A First-Principles Study

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

Li, Liang; Zhang, Rui; Vinson, John

Balancing global energy needs against increasing greenhouse gas emissions requires new methods for efficient CO 2 reduction. While photoreduction of CO 2 is a viable approach for fuel generation, the rational design of photocatalysts hinges on precise characterization of the surface catalytic reactions. Cu 2O is a promising next-generation photocatalyst, but the atomic-scale description of the interaction between CO 2 and the Cu 2O surface is largely unknown, and detailed experimental measurements are lacking. In this study, density-functional-theory (DFT) calculations have been performed to identify the Cu 2O (110) surface stoichiometry that favors CO 2 reduction. To facilitate interpretation ofmore » scanning tunneling microscopy (STM) and X-ray absorption near-edge structures (XANES) measurements, which are useful for characterizing catalytic reactions, we present simulations based on DFT-derived surface morphologies with various adsorbate types. STM and XANES simulations were performed using the Tersoff Hamann approximation and Bethe-Salpeter equation (BSE) approach, respectively. The results provide guidance for observation of CO 2 reduction reaction on, and rational surface engineering of, Cu 2O (110). In conclusion, they also demonstrate the effectiveness of computational image and spectroscopy modeling as a predictive tool for surface catalysis characterization.« less

Studies on the formation of hierarchical zeolite T aggregates with well-defined morphology in different template systems

NASA Astrophysics Data System (ADS)

Yin, Xiaoyan; Chu, Naibo; Lu, Xuewei; Li, Zhongfang; Guo, Hong

2016-01-01

In this paper, the disk-like and pumpkin-like hierarchical zeolite T aggregates consisted of primary nano-grains have been hydrothermally synthesized with and without the aid of the second template. The first template is used with tetramethylammonium hydroxide (TMAOH) and the second template is used with triethanolamine (TEA) or polyving akohol (PVA). A combination of characterization techniques, including XRD, SEM, TEM and N2 adsorption-desorption to examine the crystal crystallinity, morphology and surface properties of hierarchical zeolite T aggregates. In the single-template preparation process, the two-step varying-temperature treatment has been used to improve the meso-porosity of zeolite T aggregates. In the double-template preparation process, the amounts of PVA or TEA on the crystallinity, morphology and meso-porosity of zeolite T aggregates have been studied. It has been proved that the interstitial voids between the primary grains of aggregates are the origin of additional mesopores of samples. The micro- and meso-porosities of samples prepared with and without the second template have been contrasted in detail at last. In particular, the sample synthesized with the addition of PVA presents a hierarchical pore structure with the highest Sext value of 122 m2/g and Vmeso value of 0.255 cm3/g.

Three New Teosintes (Zea spp., Poaceae) From Mexico

USDA-ARS?s Scientific Manuscript database

The discovery of new species of teosinte from México motivated the comparative study of populations from México, Guatemala and Nicaragua through detailed ecogeographic, morphologic, cytogenetic and molecular characterization. The study involved a comparative analysis of morphological, ecogeographic,...

Comparison of SAM and OBIA as Tools for Lava Morphology Classification - A Case Study in Krafla, NE Iceland

NASA Astrophysics Data System (ADS)

Aufaristama, Muhammad; Hölbling, Daniel; Höskuldsson, Ármann; Jónsdóttir, Ingibjörg

2017-04-01

The Krafla volcanic system is part of the Icelandic North Volcanic Zone (NVZ). During Holocene, two eruptive events occurred in Krafla, 1724-1729 and 1975-1984. The last eruptive episode (1975-1984), known as the "Krafla Fires", resulted in nine volcanic eruption episodes. The total area covered by the lavas from this eruptive episode is 36 km2 and the volume is about 0.25-0.3 km3. Lava morphology is related to the characteristics of the surface morphology of a lava flow after solidification. The typical morphology of lava can be used as primary basis for the classification of lava flows when rheological properties cannot be directly observed during emplacement, and also for better understanding the behavior of lava flow models. Although mapping of lava flows in the field is relatively accurate such traditional methods are time consuming, especially when the lava covers large areas such as it is the case in Krafla. Semi-automatic mapping methods that make use of satellite remote sensing data allow for an efficient and fast mapping of lava morphology. In this study, two semi-automatic methods for lava morphology classification are presented and compared using Landsat 8 (30 m spatial resolution) and SPOT-5 (10 m spatial resolution) satellite images. For assessing the classification accuracy, the results from semi-automatic mapping were compared to the respective results from visual interpretation. On the one hand, the Spectral Angle Mapper (SAM) classification method was used. With this method an image is classified according to the spectral similarity between the image reflectance spectrums and the reference reflectance spectra. SAM successfully produced detailed lava surface morphology maps. However, the pixel-based approach partly leads to a salt-and-pepper effect. On the other hand, we applied the Random Forest (RF) classification method within an object-based image analysis (OBIA) framework. This statistical classifier uses a randomly selected subset of training samples to produce multiple decision trees. For final classification of pixels or - in the present case - image objects, the average of the class assignments probability predicted by the different decision trees is used. While the resulting OBIA classification of lava morphology types shows a high coincidence with the reference data, the approach is sensitive to the segmentation-derived image objects that constitute the base units for classification. Both semi-automatic methods produce reasonable results in the Krafla lava field, even if the identification of different pahoehoe and aa types of lava appeared to be difficult. The use of satellite remote sensing data shows a high potential for fast and efficient classification of lava morphology, particularly over large and inaccessible areas.

Intra-flow morphology variations within a single submarine flow: the 2005-2006 East Pacific Rise eruption

NASA Astrophysics Data System (ADS)

Fundis, A. T.; Soule, S.; Fornari, D. J.; Perfit, M. R.

2009-12-01

The 2005-2006 eruption near 9°50‧N marked the first observed repeat eruption at a mid-ocean ridge and provided a unique opportunity to deduce the emplacement dynamics of a single eruptive event. Since this new flow was documented in April 2006, a total of 41 deep-towed imaging surveys have been conducted with the Woods Hole Oceanographic Institution’s (WHOI) TowCam system. These surveys collected more than 60,000 digital color images and high-resolution (+ 10 cm) bathymetric profiles. We have analyzed the surface morphology of the flow using this data at a level of detail that has never before been possible. Pre-existing slope has been determined using bathymetric data previously collected with WHOI’s Autonomous Benthic Explorer and 30 kHz Simrad EM300 multibeam system. Our analyses quantify the spatial distributions of lava flow surface morphologies and allow us to investigate how these various morphologies relate to the physical characteristics of the ridge and dynamics of flow emplacement. Images of the 2005-2006 flow from each of the TowCam surveys were analyzed for lava flow morphology, the orientation of flow direction indicators, and for the presence of kipukas, collapse, faults and fissures. Our results support previous studies (Fornari et al., 1998, 2004; Soule et al., 2005) that suggest most of the 2005-2006 flows originated from nearly continuous fissures as discrete flow units and subsequently followed pre-existing bathymetric lows and flow channels away from the AST. These flow channels, found predominantly on the eastern flank of the ridge axis at ~9°50‧N, are primarily composed of transitions between sheet and hackly flows. The flows north of 9°53‧ and south of 9°49‧ are predominantly lobate flows with a high abundance of kipukas (<1 - 5 m diameter). The centers of lava channels that served as distribution pathways during the eruption tend to be characterized by sheet flows, while hackly flows that transition into lobate define the edges of the channels. Pillows, that are relatively rare, are concentrated at the termini of the flow lobes. The data indicate that the pre-existing slope did not influence the development of various morphologies of the 2005-2006 eruption.

Geomorphic Mapping and Paleoterrain Generation for use in Modeling Holocene (8,000 1,500 yr) Agropastoral Landuse and Landscape Interactions in Southeast Spain

NASA Astrophysics Data System (ADS)

Arrowsmith, J. R.; Dimaggio, E. N.; Barton, C. M.; Sarjoughian, H. S.; Fall, P.; Falconer, S. E.; Ullah, I. I.

2006-12-01

Dramatic changes in land use were associated with the rise of agriculture in the mid Holocene. Both the surface properties and the drainage networks were changed. Along with the direct modifications to surface properties (vegetation change, sediment liberation, and compaction) and drainage network alteration (terracing, canals), up and downstream responses in the watersheds communicated these changes throughout the landscape. The magnitude, rate, and feedbacks with the growing human populations are critical questions in our effort to assess human-landscape interactions. Our interdisciplinary team has focused on two field sites around the Mediterranean for model development and testing. We are combining high resolution process- based models of landscape change implemented within the GRASS GIS with agent based models of agropastoral behavior and driven by high resolution climate and vegetation models. In the Spanish field area (Penaguila Valley, 38.41 N 0.23 W), we have produced detailed (1:10,000) geomorphic maps which we combine with high resolution Digital Elevation Models (DEMs) on which we can run the surface process models to assess the portions of the landscape that are most sensitive to the postulated agropastoral landuse changes. To support this modeling we have produced the 1 m DEMs from softcopy photogrammetry. This DEM has greatly improved our overall spatial resolution to permit more accurate terrace correlations and improved quantitative assessment of morphologic processes (e.g. channel erosion, slope stability). In stereo, we have mapped overall landscape morphology that emphasizes areas of active erosion and alluvial terrace surfaces. Alluvial terraces are crucial to this research because they record periods of past stable topography and those of mid Holocene age were settled and farmed. We have correlated mapped terraces across the landscape using elevation and morphological distinctions. Using ArcGIS, we interpolated surfaces across equivalent terraces using triangulated irregular networks (TINs) allowing reconstruction of multiple regional landscapes to establish a chronosequence of absolute landscape change. This mapping and reconstruction will be field checked and numerical age constraints applied. Interestingly, our tentative age assessment of the lowest broad surface indicates that it was occupied about 5 ka, and now has been incised by 20 m. Archeological sites have been cut by the incision. This change from a broad low relief alluvial surface to one cut by narrow channels may have been an important change for the local populations and caused them to change their behaviors, even though it may have been initially triggered by distributed landscape change in the watershed, due to agropastoral activities.

Effect of Surface Morphology and Magnetic Impurities on the Electronic Structure in Cobalt-Doped BaFe 2 As 2 Superconductors

DOE PAGES

Zou, Qiang; Wu, Zhiming; Fu, Mingming; ...

2017-02-03

Combined scanning tunneling microscopy, spectroscopy, and local barrier height (LBH) studies show that low-temperature-cleaved optimally doped Ba(Fe 1–xCo x) 2As 2 crystals with x = 0.06, with T c = 22 K, have complicated morphologies. Although the cleavage surface and hence the morphologies are variable, the superconducting gap maps show the same gap widths and nanometer size inhomogeneities irrelevant to the morphology. Based on the spectroscopy and LBH maps, the bright patches and dark stripes in the morphologies are identified as Ba- and As-dominated surface terminations, respectively. Magnetic impurities, possibly due to Co or Fe atoms, are believed to createmore » local in-gap state and, in addition, suppress the superconducting coherence peaks. Lastly, this study will clarify the confusion on the cleavage surface terminations of the Fe-based superconductors and its relation with the electronic structures.« less

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.

[High resolution functional magnetic resonance tomography with Gd-DTPA eyedrops in diagnosis of lacrimal apparatus diseases].

PubMed

Hoffmann, K T; Anders, N; Hosten, N; Holschbach, A; Walkow, T; Sörensen, R; Hartmann, C; Felix, R

1998-08-01

Both dacryocystography and dacryoscintigraphy are well established in the evaluation of stenoses of the lacrimal drainage system. They provide limited information about the ductal anatomy itself and about periductal structures. MR imaging was evaluated for its capability to directly visualize the lacrimal drainage system in detail and simultaneously provide functional characterization of dacryostenosis. Twenty-seven lacrimal drainage systems of 23 patients suffering from epiphora were examined in an MR unit before and after conjunctival and intravenous application of Gd-DTPA using a surface coil. Dacryostenosis was found in 23 of 27 lacrimal systems. Stenoses were localized to the canalicular (n = 3), saccular (n = 8), and ductal (n = 12) level, and were classified as stenosis or occlusion. MR imaging with conjunctival contrast application allows within one examination both detailed morphological and functional assessment of the lacrimal drainage system with depiction of surrounding structures. Limitations arise mainly from demands on technical and patient-related preconditions.

Surface zwitterionicalization of poly(vinylidene fluoride) membranes from the entrapped reactive core-shell silica nanoparticles.

PubMed

Zhu, Li-Jing; Zhu, Li-Ping; Zhang, Pei-Bin; Zhu, Bao-Ku; Xu, You-Yi

2016-04-15

We demonstrate the preparation and properties of poly(vinylidene fluoride) (PVDF) filtration membranes modified via surface zwitterionicalization mediated by reactive core-shell silica nanoparticles (SiO2 NPs). The organic/inorganic hybrid SiO2 NPs grafted with poly(methyl meth acrylate)-block-poly(2-dimethylaminoethyl methacrylate) copolymer (PMMA-b-PDMAEMA) shell were prepared by surface-initiated reversible addition fragmentation chain transfer (SI-RAFT) polymerization and then used as a membrane-making additive of PVDF membranes. The PDMAEMA exposed on membrane surface and pore walls were quaternized into zwitterionic poly(sulfobetaine methacrylate) (PSBMA) using 1,3-propane sultone (1,3-PS) as the quaternization agent. The membrane surface chemistry and morphology were analyzed by attenuated total reflectance Fourier transform infrared spectroscopy (ATR-FTIR), X-ray photoelectron spectroscopy (XPS) and scanning electron microscopy (SEM), respectively. The hydrophilicity, permeability and antifouling ability of the investigated membranes were evaluated in detail. It was found that the PSBMA chains brought highly-hydrophilic and strong fouling resistant characteristics to PVDF membranes due to the powerful hydration of zwitterionic surface. The SiO2 cores and PMMA chains in the hybrid NPs play a role of anchors for the linking of PSBMA chains to membrane surface. Compared to the traditional strategies for membrane hydrophilic modification, the developed method in this work combined the advantages of both blending and surface reaction. Copyright © 2016 Elsevier Inc. All rights reserved.

Hollow-structured mesoporous materials: chemical synthesis, functionalization and applications.

PubMed

Li, Yongsheng; Shi, Jianlin

2014-05-28

Hollow-structured mesoporous materials (HMMs), as a kind of mesoporous material with unique morphology, have been of great interest in the past decade because of the subtle combination of the hollow architecture with the mesoporous nanostructure. Benefitting from the merits of low density, large void space, large specific surface area, and, especially, the good biocompatibility, HMMs present promising application prospects in various fields, such as adsorption and storage, confined catalysis when catalytically active species are incorporated in the core and/or shell, controlled drug release, targeted drug delivery, and simultaneous diagnosis and therapy of cancers when the surface and/or core of the HMMs are functionalized with functional ligands and/or nanoparticles, and so on. In this review, recent progress in the design, synthesis, functionalization, and applications of hollow mesoporous materials are discussed. Two main synthetic strategies, soft-templating and hard-templating routes, are broadly sorted and described in detail. Progress in the main application aspects of HMMs, such as adsorption and storage, catalysis, and biomedicine, are also discussed in detail in this article, in terms of the unique features of the combined large void space in the core and the mesoporous network in the shell. Functionalization of the core and pore/outer surfaces with functional organic groups and/or nanoparticles, and their performance, are summarized in this article. Finally, an outlook of their prospects and challenges in terms of their controlled synthesis and scaled application is presented. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Crystallization, mechanical properties, and controlled enzymatic degradation of biodegradable poly(epsilon-caprolactone)/multi-walled carbon nanotubes nanocomposites.

PubMed

Qiu, Zhaobin; Wang, Huishan; Xu, Changling

2011-09-01

Biodegradable poly(epsilon-caprolactone) (PCL)/multi-walled carbon nanotubes containing carboxylic groups (f-MWNTs) nanocomposites were prepared via simple melt compounding at low f-MWNTs loading in this work. Scanning and transmission electron microscopy observations indicate a homogeneous and fine distribution of f-MWNTs throughout the PCL matrix. The effect of low f-MWNTs loading on the crystallization, mechanical properties, and controlled enzymatic degradation of PCL in the nanocomposites were studied in detail with various techniques. The experimental results indicate that the incorporation of f-MWNTs enhances both the nonisothermal crystallization peak temperature and the overall isothermal crystallization rate of PCL in the PCL/f-MWNTs nanocomposites relative to neat PCL; moreover, the incorporation of a small quantity of f-MWNTs has improved apparently the mechanical properties of the PCL/MWNTs nanocomposites compared to neat PCL. The enzymatic degradation of neat PCL and the PCL/f-MWNTs nanocomposites at low f-MWNTs loading was studied in detail. The variation of weight loss with enzymatic degradation time, the surface morphology change, the reduced film thickness, the appearance of f-MWNTs on the surface of the films, and the almost unchanged molecular weight after enzymatic degradation suggest that the enzymatic degradation of neat PCL and the PCL/f-MWNTs nanocomposites may proceed via surface erosion mechanism. The presence of f-MWNTs reduces the enzymatic degradation rate of the PCL matrix in the nanocomposites compared with that of the pure PCL film.

Comparative Morphology and Histology of the Nasal Fossa in Four Mammals: Gray Squirrel, Bobcat, Coyote, and White-Tailed Deer.

PubMed

Yee, Karen K; Craven, Brent A; Wysocki, Charles J; Van Valkenburgh, Blaire

2016-07-01

Although the anatomy of the nasal fossa is broadly similar among terrestrial mammals, differences are evident in the intricacies of nasal turbinal architecture, which varies from simple scroll-like to complex branching forms, and in the extent of nonsensory and olfactory epithelium covering the turbinals. In this study, detailed morphological and immunohistochemical examinations and quantitative measurements of the turbinals and epithelial lining of the nasal fossa were conducted in an array of species that include the gray squirrel, bobcat, coyote, and white-tailed deer. Results show that much more of the nose is lined with olfactory epithelium in the smallest species (gray squirrel) than in the larger species. In two species with similar body masses, bobcat and coyote, the foreshortened felid snout influences turbinal size and results in a decrease of olfactory epithelium on the ethmoturbinals relative to the longer canine snout. Ethmoturbinal surface area exceeds that of the maxilloturbinals in all four sampled animals, except the white-tailed deer, in which the two are similar in size. Combining our results with published data from a broader array of mammalian noses, it is apparent that olfactory epithelial surface area is influenced by body mass, but is also affected by aspects of life history, such as diet and habitat, as well as skull morphology, itself a product of multiple compromises between various functions, such as feeding, vision, and cognition. The results of this study warrant further examination of other mammalian noses to broaden our evolutionary understanding of nasal fossa anatomy. Anat Rec, 299:840-852, 2016. © 2016 Wiley Periodicals, Inc. © 2016 Wiley Periodicals, Inc.

The lid wiper and muco-cutaneous junction anatomy of the human eyelid margins: an in vivo confocal and histological study

PubMed Central

Knop, Erich; Knop, Nadja; Zhivov, Andrey; Kraak, Robert; Korb, Donald R; Blackie, Caroline; Greiner, Jack V; Guthoff, Rudolf

2011-01-01

The inner border of the eyelid margin is critically important for ocular surface integrity because it guarantees the thin spread of the tear film. Its exact morphology in the human is still insufficiently known. The histology in serial sections of upper and lower lid margins in whole-mount specimens from 10 human body donors was compared to in vivo confocal microscopy of eight eyes with a Heidelberg retina-tomograph (HRT II) and attached Rostock cornea module. Behind the posterior margin of the Meibomian orifices, the cornified epidermis stopped abruptly and was replaced by a continuous layer of para-keratinized (pk) cells followed by discontinuous pk cells. The pk cells covered the muco-cutaneous junction (MCJ), the surface of which corresponded to the line of Marx (0.2–0.3 mm wide). Then a stratified epithelium with a conjunctival structure of cuboidal cells, some pk cells, and goblet cells formed an epithelial elevation of typically about 100 μm initial thickness (lid wiper). This continued for 0.3–1.5 mm and formed a slope. The MCJ and lid wiper extended all along the lid margin from nasal to temporal positions in the upper and lower lids. Details of the epithelium and connective tissue were also detectable using the Rostock cornea module. The human inner lid border has distinct zones. Due to its location and morphology, the epithelial lip of the lid wiper appears a suitable structure to spread the tear film and is distinct from the MCJ/line of Marx. Better knowledge of the lid margin appears important for understanding dry eye disease and its morphology can be analysed clinically by in vivo confocal microscopy. PMID:21413985

Morphological study of the European hedgehog (Erinaceus europaeus) tongue by SEM and LM.

PubMed

Akbari, Ghasem; Babaei, Mohammad; Hassanzadeh, Belal

2018-03-01

The hedgehog tongue is a tactile and taste organ which carries out various functions. Detailed functional and morphological studies are required to clearly define the relationship of the hedgehog tongue with taste, food palatability, mastication and swallowing of food, as well as the production of sounds. The aim of this study was to determine the relationship between the morphological characteristics of the European hedgehog tongue and the lifestyle of this animal, as well as to compare findings with the results of studies on other vertebrates. Gross and micro-anatomical light and scanning electron microscopy studies revealed that the hedgehog tongue could be divided in three areas, namely the apex, body and root. A keratinized stratified squamous epithelium, which was smooth on the ventral surface but bore four types of papillae on the dorsal surface, lined the tongue. Three types of these papillae were found to have gustatory functions and to express their activity in close relation with the salivary glands. These simple conical filiform papillae were situated caudally and distributed one after the other without a break. The dome-shaped fungiform papillae on the apex, with the highest distribution rate on the apex edge, were small, but those on the body and root were large. The three circular vallate papillae were arranged in a triangular shape. The foliate papillae with a few tiny projections, found in a shallow furrow, were situated between the root and the body. Most of the nerve fibers observed in different sections of the tongue tissue were of the unmyelinated type, confirming that the main task of the hedgehog tongue was its gustatory function.

Influence of multi-wavelength laser irradiation of enamel and dentin surfaces at 0.355, 2.94, and 9.4 μm on surface morphology, permeability, and acid resistance.

PubMed

Chang, Nai-Yuan N; Jew, Jamison M; Simon, Jacob C; Chen, Kenneth H; Lee, Robert C; Fried, William A; Cho, Jinny; Darling, Cynthia L; Fried, Daniel

2017-12-01

Ultraviolet (UV) and infrared (IR) lasers can be used to specifically target protein, water, and mineral, respectively, in dental hard tissues to produce varying changes in surface morphology, permeability, reflectivity, and acid resistance. The purpose of this study was to explore the influence of laser irradiation and topical fluoride application on the surface morphology, permeability, reflectivity, and acid resistance of enamel and dentin to shed light on the mechanism of interaction and develop more effective treatments. Twelve bovine enamel surfaces and twelve bovine dentin surfaces were irradiated with various combinations of lasers operating at 0.355 (Freq.-tripled Nd:YAG (UV) laser), 2.94 (Er:YAG laser), and 9.4 μm (CO 2 laser), and surfaces were exposed to an acidulated phosphate fluoride gel and an acid challenge. Changes in the surface morphology, acid resistance, and permeability were measured using digital microscopy, polarized light microscopy, near-IR reflectance, fluorescence, polarization sensitive-optical coherence tomography (PS-OCT), and surface dehydration rate measurements. Different laser treatments dramatically influenced the surface morphology and permeability of both enamel and dentin. CO 2 laser irradiation melted tooth surfaces. Er:YAG and UV lasers, while not melting tooth surfaces, showed markedly different surface roughness. Er:YAG irradiation led to significantly rougher enamel and dentin surfaces and led to higher permeability. There were significant differences in acid resistance among the various treatment groups. Surface dehydration measurements showed significant changes in permeability after laser treatments, application of fluoride and after exposure to demineralization. CO 2 laser irradiation was most effective in inhibiting demineralization on enamel while topical fluoride was most effective for dentin surfaces. Lasers Surg. Med. 49:913-927, 2017. © 2017 Wiley Periodicals, Inc. © 2017 Wiley Periodicals, Inc.

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.

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.

Understanding and controlling morphology formation in Langmuir-Blodgett block copolymer films using PS-P4VP and PS-P4VP/PDP.

PubMed

Perepichka, Iryna I; Lu, Qing; Badia, Antonella; Bazuin, C Geraldine

2013-04-09

This contribution offers a comprehensive understanding of the factors that govern the morphologies of Langmuir-Blodgett (LB) monolayers of amphiphilic diblock copolymers (BCs). This is achieved by a detailed investigation of a wide range of polystyrene-poly(4-vinyl pyridine) (PS-P4VP) block copolymers, in contrast to much more limited ranges in previous studies. Parameters that are varied include the block ratios (mainly for similar total molecular weights, occasionally other total molecular weights), the presence or not of 3-n-pentadecylphenol (PDP, usually equimolar with VP, with which it hydrogen bonds), the spreading solution concentration ("low" and "high"), and the LB technique (standard vs "solvent-assisted"). Our observations are compared with previously published results on other amphiphilic diblock copolymers, which had given rise to contradictory interpretations of morphology formation. Based on the accumulated results, we re-establish early literature conclusions that three main categories of LB block copolymer morphologies are obtained depending on the block ratio, termed planar, strand, and dot regimes. The block composition boundaries in terms of mol % block content are shown to be similar for all BCs having alkyl chain substituents on the hydrophilic block (such as PS-P4VP/PDP) and are shifted to higher values for BCs with no alkyl chain substituents (such as PS-P4VP). This is attributed to the higher surface area per repeat unit of the hydrophilic block monolayer on the water surface for the former, as supported by the onset and limiting areas of the Langmuir isotherms for the BCs in the dot regime. 2D phase diagrams are discussed in terms of relative effective surface areas of the two blocks. We identify and discuss how kinetic effects on morphology formation, which have been highlighted in more recent literature, are superposed on the compositional effects. The kinetic effects are shown to depend on the morphology regime, most strongly influencing the strand and, especially, planar regimes, where they give rise to a diversity of specific structures. Besides film dewetting mechanisms, which are different when occurring in structured versus unstructured films (the latter previously discussed in the literature), kinetic influences are discussed in terms of chain association dynamics leading to depletion effects that impact on growing aggregates. These depletion effects particularly manifest themselves in more dilute spreading solutions, with higher molecular weight polymers, and in composition regimes characterized by equilibrium degrees of aggregation that are effectively infinite. It is by understanding these various kinetic influences that the diversity of structures can be classified by the three main composition-dependent regimes.

Microscopic morphology evolution during ion beam smoothing of Zerodur® surfaces.

PubMed

Liao, Wenlin; Dai, Yifan; Xie, Xuhui; Zhou, Lin

2014-01-13

Ion sputtering of Zerodur material often results in the formation of nanoscale microstructures on the surfaces, which seriously influences optical surface quality. In this paper, we describe the microscopic morphology evolution during ion sputtering of Zerodur surfaces through experimental researches and theoretical analysis, which shows that preferential sputtering together with curvature-dependent sputtering overcomes ion-induced smoothing mechanisms leading to granular nanopatterns formation in morphology and the coarsening of the surface. Consequently, we propose a new method for ion beam smoothing (IBS) of Zerodur optics assisted by deterministic ion beam material adding (IBA) technology. With this method, Zerodur optics with surface roughness down to 0.15 nm root mean square (RMS) level is obtained through the experimental investigation, which demonstrates the feasibility of our proposed method.

Topographic Evidence for Eruptive Style Changes and Magma Evolution of Small Plains-style Volcanoes on Earth and Mars

NASA Technical Reports Server (NTRS)

Hughes, S. S.; Sakimoto, S. E.H.; Gregg, T. K. P.; Chadwick, D. J.; Brady, S. B.; Farley, M. A.; Holmes, A. A. .; Semple, A. M.; Weren, S.L.

2004-01-01

Topographic profiles and surface characteristics of small (5 - 25 km diameter) plains-style shield volcanoes on the eastern Snake River Plain (ESRP) provide a method to evaluate eruptive processes and magmatic evolution on Martian volcanic plains. The ESRP is an ideal place to observe Mars-like volcanic features where hundreds of small monogenetic basaltic shields dominate the volcanic-sedimentary depositional sequence, and numerous planetary analogues are evident: coalescent mafic shields, hydromagmatic explosive eruptions, the interaction of lava flows with surficial water and glacial ice, and abundant eolian sand and loess. Single flows cannot be correlated over great distances, and are spatially restricted. These relations are useful for planetary exploration when inferring volcanic evolutionary patterns in lava plains represented by numerous eruptive vents. High spatial resolution imagery and digital topographic data for Mars from MOC, MOLA, and THEMIS is allowing for improvements in the level of detail of stratigraphic mapping of fields of small (< 25 km in diameter) volcanoes as well as studies of the morphological characteristics of individual volcanoes. In order to compare Mars and Earth volcanic features, elevation data from U.S.G.S. 10-meter digital elevation models (DEMs) and high-precision GPS field measurements are used in this study to generate approx. 20m spacing topographic profiles from which slope and surface morphology can be extracted. Average ESRP flank and crater slopes are calculated using 100 - 200 m spacing for optimum comparison to MOLA data, and to reduce the effects of surface irregularities.

A Combination of Ex vivo Diffusion MRI and Multiphoton to Study Microglia/Monocytes Alterations after Spinal Cord Injury

PubMed Central

Noristani, Harun N.; Boukhaddaoui, Hassan; Saint-Martin, Guillaume; Auzer, Pauline; Sidiboulenouar, Rahima; Lonjon, Nicolas; Alibert, Eric; Tricaud, Nicolas; Goze-Bac, Christophe; Coillot, Christophe; Perrin, Florence E.

2017-01-01

Central nervous system (CNS) injury has been observed to lead to microglia activation and monocytes infiltration at the lesion site. Ex vivo diffusion magnetic resonance imaging (diffusion MRI or DWI) allows detailed examination of CNS tissues, and recent advances in clearing procedures allow detailed imaging of fluorescent-labeled cells at high resolution. No study has yet combined ex vivo diffusion MRI and clearing procedures to establish a possible link between microglia/monocytes response and diffusion coefficient in the context of spinal cord injury (SCI). We carried out ex vivo MRI of the spinal cord at different time-points after spinal cord transection followed by tetrahydrofuran based clearing and examined the density and morphology of microglia/monocytes using two-photon microscopy. Quantitative analysis revealed an early marked increase in microglial/monocytes density that is associated with an increase in the extension of the lesion measured using diffusion MRI. Morphological examination of microglia/monocytes somata at the lesion site revealed a significant increase in their surface area and volume as early as 72 hours post-injury. Time-course analysis showed differential microglial/monocytes response rostral and caudal to the lesion site. Microglia/monocytes showed a decrease in reactivity over time caudal to the lesion site, but an increase was observed rostrally. Direct comparison of microglia/monocytes morphology, obtained through multiphoton, and the longitudinal apparent diffusion coefficient (ADC), measured with diffusion MRI, highlighted that axonal integrity does not correlate with the density of microglia/monocytes or their somata morphology. We emphasize that differential microglial/monocytes reactivity rostral and caudal to the lesion site may thus coincide, at least partially, with reported temporal differences in debris clearance. Our study demonstrates that the combination of ex vivo diffusion MRI and two-photon microscopy may be used to follow structural tissue alteration. Lesion extension coincides with microglia/monocytes density; however, a direct relationship between ADC and microglia/monocytes density and morphology was not observed. We highlighted a differential rostro-caudal microglia/monocytes reactivity that may correspond to a temporal difference in debris clearance and axonal integrity. Thus, potential therapeutic strategies targeting microglia/monocytes after SCI may need to be adjusted not only with the time after injury but also relative to the location to the lesion site. PMID:28769787

Wrinkling pattern evolution of cylindrical biological tissues with differential growth.

PubMed

Jia, Fei; Li, Bo; Cao, Yan-Ping; Xie, Wei-Hua; Feng, Xi-Qiao

2015-01-01

Three-dimensional surface wrinkling of soft cylindrical tissues induced by differential growth is explored. Differential volumetric growth can cause their morphological stability, leading to the formation of hexagonal and labyrinth wrinkles. During postbuckling, multiple bifurcations and morphological transitions may occur as a consequence of continuous growth in the surface layer. The physical mechanisms underpinning the morphological evolution are examined from the viewpoint of energy. Surface curvature is found to play a regulatory role in the pattern evolution. This study may not only help understand the morphogenesis of soft biological tissues, but also inspire novel routes for creating desired surface patterns of soft materials.

Correlation between surface morphology and electrical properties of VO2 films grown by direct thermal oxidation method

NASA Astrophysics Data System (ADS)

Yoon, Joonseok; Park, Changwoo; Park, Sungkyun; Mun, Bongjin Simon; Ju, Honglyoul

2015-10-01

We investigate surface morphology and electrical properties of VO2 films fabricated by direct thermal oxidation method. The VO2 film prepared with oxidation temperature at 580 °C exhibits excellent qualities of VO2 characteristics, e.g. a metal-insulator transition (MIT) near 67 °C, a resistivity ratio of ∼2.3 × 104, and a bandgap of 0.7 eV. The analysis of surface morphology with electrical resistivity of VO2 films reveals that the transport properties of VO2 films are closely related to the grain size and surface roughness that vary with oxidation annealing temperatures.

Crystallization of calcium oxalate monohydrate at dipalmitoylphosphatidylcholine monolayers in the presence of chondroitin sulfate A

NASA Astrophysics Data System (ADS)

Ouyang, Jian-Ming; Deng, Sui-Ping; Zhong, Jiu-Ping; Tieke, Bernd; Yu, Shu-Hong

2004-10-01

The growth and aggregation of calcium oxalate monohydrate (COM) crystals beneath dipalmitoylphosphatidylcholine (DPPC) monolayers in the presence of chondroitin sulfate A (C4S) was systematically examined under different surface pressure. The results indicated that the addition of C4S can inhibit the crystal growth and prevent the aggregation of COM crystals. Under a DPPC monolayer, well-defined three-dimensional hexagonal prisms and three-dimensional rhombus prisms with sharply angled tips were obtained. The DPPC monolayer at a surface pressure of 10 mN/m can match the Ca2+ distance of the (1 bar 0 1) face of COM better than at 20 mN/m. The addition of C4S could cooperatively modulate the interaction strength between the monolayer (or itself) with the specific morphology determining faces such as (1 bar 0 1) and (0 2 0), and thus results in remarkable stabilization of the (1 bar 0 1) faces. The dramatic changes in morphological details were due to the strong electrostatic interactions between the Ca2+-rich (1 bar 0 1) crystal faces of COM and the polyanionic polysaccharide C4S together with the negatively charged sites of the zwitterionic DPPC monolayers. The increase of the concentration of C4S can further enhance the stabilization of the (1 bar 0 1) face.

Lyman Break Analogs: Constraints on the Formation of Extreme Starbursts at Low and High Redshift

NASA Technical Reports Server (NTRS)

Goncalves, Thiago S.; Overzier, Roderik; Basu-Zych, Antara; Martin, D. Christopher

2011-01-01

Lyman Break Analogs (LBAs), characterized by high far-UV luminosities and surface brightnesses as detected by GALEX, are intensely star-forming galaxies in the low-redshift universe (z approximately equal to 0.2), with star formation rates reaching up to 50 times that of the Milky Way. These objects present metallicities, morphologies and other physical properties similar to higher redshift Lyman Break Galaxies (LBGs), motivating the detailed study of LBAs as local laboratories of this high-redshift galaxy population. We present results from our recent integral-field spectroscopy survey of LBAs with Keck/OSIRIS, which shows that these galaxies have the same nebular gas kinematic properties as high-redshift LBGs. We argue that such kinematic studies alone are not an appropriate diagnostic to rule out merger events as the trigger for the observed starburst. Comparison between the kinematic analysis and morphological indices from HST imaging illustrates the difficulties of properly identifying (minor or major) merger events, with no clear correlation between the results using either of the two methods. Artificial redshifting of our data indicates that this problem becomes even worse at high redshift due to surface brightness dimming and resolution loss. Whether mergers could generate the observed kinematic properties is strongly dependent on gas fractions in these galaxies. We present preliminary results of a CARMA survey for LBAs and discuss the implications of the inferred molecular gas masses for formation models.

Efficient colloidal route to pure phase kesterite Cu2ZnSnS4 (CZTS) nanocrystals with controlled shape and structure

NASA Astrophysics Data System (ADS)

Jain, Shefali; Chawla, Parul; Sharma, Shailesh Narain; Singh, Dinesh; Vijayan, N.

2018-07-01

This work reports the synthesis of varied shaped Cu2ZnSnS4 (CZTS) nano inks in a most stable kesterite phase via a hot injection colloidal route. CZTS nanoparticles of varied shape were synthesized by using various capping ligands with the introduction of butylamine as a new capping ligand and two different sulfur precursors respectively. The shape of the as-synthesized kesterite CZTS nanocrystals can be well controlled in the form of nanofibers, spherical nanoparticles, nano hexagons, nanotriangles, and nanodiscs. A detailed analysis of the effects of various capping ligand and sulfur source on reaction conditions to obtain pure phase kesterite CZTS nanocrystals for different shapes is explained using LaMer's diagram. It has been found that the choice of sulfur precursor also plays an important role in determining the symmetry and orientation of the plane of the CZTS nanocrystals. Due to different morphology and capping ligands present on the surface, diverse surface properties were obtained which was confirmed by contact angle measurements. The variation in the band gap was also found with changes in morphology of kesterite phased CZTS nanoparticles. Due to variations obtained in band gap, changes in I-V characteristics were also observed which may leads different CZTS nanoparticles to have their potential applications in different regime other than photovoltaics like sensors, photocatalysis etc.

A monolayer of hierarchical silver hemi-mesoparticles with tunable surface topographies for highly sensitive surface-enhanced Raman spectroscopy

NASA Astrophysics Data System (ADS)

Zhu, Shuangmei; Fan, Chunzhen; Mao, Yanchao; Wang, Junqiao; He, Jinna; Liang, Erjun; Chao, Mingju

2016-02-01

We proposed a facile green synthesis system to synthesize large-scale Ag hemi-mesoparticles monolayer on Cu foil. Ag hemi-mesoparticles have different surface morphologies on their surfaces, including ridge-like, meatball-like, and fluffy-like shapes. In the reaction, silver nitrate was reduced by copper at room temperature in dimethyl sulfoxide via the galvanic displacement reaction. The different surface morphologies of the Ag hemi-mesoparticles were adjusted by changing the reaction time, and the hemi-mesoparticle surface formed fluffy-spherical nanoprotrusions at longer reaction time. At the same time, we explored the growth mechanism of silver hemi-mesoparticles with different surface morphologies. With 4-mercaptobenzoic acid as Raman probe molecules, the fluffy-like silver hemi-mesoparticles monolayer with the best activity of surface enhanced Raman scattering (SERS), the enhancement factor is up to 7.33 × 107 and the detection limit can reach 10-10M. SERS measurements demonstrate that these Ag hemi-mesoparticles can serve as sensitive SERS substrates. At the same time, using finite element method, the distribution of the localized electromagnetic field near the particle surface was simulated to verify the enhanced mechanism. This study helps us to understand the relationship between morphology Ag hemi-mesoparicles and the properties of SERS.

A monolayer of hierarchical silver hemi-mesoparticles with tunable surface topographies for highly sensitive surface-enhanced Raman spectroscopy.

PubMed

Zhu, Shuangmei; Fan, Chunzhen; Mao, Yanchao; Wang, Junqiao; He, Jinna; Liang, Erjun; Chao, Mingju

2016-02-21

We proposed a facile green synthesis system to synthesize large-scale Ag hemi-mesoparticles monolayer on Cu foil. Ag hemi-mesoparticles have different surface morphologies on their surfaces, including ridge-like, meatball-like, and fluffy-like shapes. In the reaction, silver nitrate was reduced by copper at room temperature in dimethyl sulfoxide via the galvanic displacement reaction. The different surface morphologies of the Ag hemi-mesoparticles were adjusted by changing the reaction time, and the hemi-mesoparticle surface formed fluffy-spherical nanoprotrusions at longer reaction time. At the same time, we explored the growth mechanism of silver hemi-mesoparticles with different surface morphologies. With 4-mercaptobenzoic acid as Raman probe molecules, the fluffy-like silver hemi-mesoparticles monolayer with the best activity of surface enhanced Raman scattering (SERS), the enhancement factor is up to 7.33 × 10(7) and the detection limit can reach 10(-10)M. SERS measurements demonstrate that these Ag hemi-mesoparticles can serve as sensitive SERS substrates. At the same time, using finite element method, the distribution of the localized electromagnetic field near the particle surface was simulated to verify the enhanced mechanism. This study helps us to understand the relationship between morphology Ag hemi-mesoparicles and the properties of SERS.

Mimicking bug-like surface structures and their fluid transport produced by ultrashort laser pulse irradiation of steel

NASA Astrophysics Data System (ADS)

Kirner, S. V.; Hermens, U.; Mimidis, A.; Skoulas, E.; Florian, C.; Hischen, F.; Plamadeala, C.; Baumgartner, W.; Winands, K.; Mescheder, H.; Krüger, J.; Solis, J.; Siegel, J.; Stratakis, E.; Bonse, J.

2017-12-01

Ultrashort laser pulses with durations in the fs-to-ps range were used for large area surface processing of steel aimed at mimicking the morphology and extraordinary wetting behaviour of bark bugs (Aradidae) found in nature. The processing was performed by scanning the laser beam over the surface of polished flat sample surfaces. A systematic variation of the laser processing parameters (peak fluence and effective number of pulses per spot diameter) allowed the identification of different regimes associated with characteristic surface morphologies (laser-induced periodic surface structures, i.e., LIPSS, grooves, spikes, etc.). Moreover, different laser processing strategies, varying laser wavelength, pulse duration, angle of incidence, irradiation atmosphere, and repetition rates, allowed to achieve a range of morphologies that resemble specific structures found on bark bugs. For identifying the ideal combination of parameters for mimicking bug-like structures, the surfaces were inspected by scanning electron microscopy. In particular, tilted micrometre-sized spikes are the best match for the structure found on bark bugs. Complementary to the morphology study, the wetting behaviour of the surface structures for water and oil was examined in terms of philic/phobic nature and fluid transport. These results point out a route towards reproducing complex surface structures inspired by nature and their functional response in technologically relevant materials.

Nanoscale Roughness and Morphology Affect the IsoElectric Point of Titania Surfaces

PubMed Central

Borghi, Francesca; Vyas, Varun; Podestà, Alessandro; Milani, Paolo

2013-01-01

We report on the systematic investigation of the role of surface nanoscale roughness and morphology on the charging behaviour of nanostructured titania (TiO2) surfaces in aqueous solutions. IsoElectric Points (IEPs) of surfaces have been characterized by direct measurement of the electrostatic double layer interactions between titania surfaces and the micrometer-sized spherical silica probe of an atomic force microscope in NaCl aqueous electrolyte. The use of a colloidal probe provides well-defined interaction geometry and allows effectively probing the overall effect of nanoscale morphology. By using supersonic cluster beam deposition to fabricate nanostructured titania films, we achieved a quantitative control over the surface morphological parameters. We performed a systematical exploration of the electrical double layer properties in different interaction regimes characterized by different ratios of characteristic nanometric lengths of the system: the surface rms roughness Rq, the correlation length ξ and the Debye length λD. We observed a remarkable reduction by several pH units of IEP on rough nanostructured surfaces, with respect to flat crystalline rutile TiO2. In order to explain the observed behavior of IEP, we consider the roughness-induced self-overlap of the electrical double layers as a potential source of deviation from the trend expected for flat surfaces. PMID:23874708

Further study on Physaloptera clausa Rudolphi, 1819 (Spirurida: Physalopteridae) from the Amur hedgehog Erinaceus amurensis Schrenk (Eulipotyphla: Erinaceidae).

PubMed

Chen, Hui-Xia; Ju, Hui-Dong; Li, Yang; Li, Liang

2017-12-20

In the present study, light and scanning electron microscopy (SEM) were used to further study the detailed morphology of Physaloptera clausa Rudolphi, 1819, based on the material collected from the Amur hedgehog E. amurensis Schrenk in China. The results revealed a few previously unreported morphological features and some morphological and morphometric variability between our specimens and the previous studies. The present supplementary morphological characters and morphometric data could help us to recognize this species more accurately.

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.

Micromorphology of cactus-pear (Opuntia ficus-indica (L.) Mill) cladodes based on scanning microscopies.

PubMed

Ben Salem-Fnayou, Asma; Zemni, Hassène; Nefzaoui, Ali; Ghorbel, Abdelwahed

2014-01-01

Cladode ultrastructural features of two prickly and two spineless Opuntia ficus-indica cultivars were examined using environmental scanning electron and atomic force microscopies. Observations focused on cladode as well as spine and glochid surface micromorphologies. Prickly cultivars were characterized by abundant cracked epicuticular wax deposits covering the cladode surface, with an amorphous structure as observed by AFM, while less abundant waxy plates were observed by ESEM on spineless cultivar cladodes. Further AFM observations allowed a rough granular and crystalloid epicuticular wax structure to be distinguished in spineless cultivars. Regarding spine micromorphology, prickly cultivars had strong persistent spines, observed by ESEM as a compact arrangement of oblong epidermal cells with a rough granular structure. However, deciduous spines in spineless cultivars had a broken transversely fissured epidermis covering a parallel arrangement of fibres. Through AFM, the deciduous spine surface presented an irregular hilly and smooth microrelief while persistent spines exhibited rough helical filamentous prints. ESEM and AFM studies of cladode surfaces from prickly and spineless cactus pear cultivars revealed valuable micro-morphological details that ought to be extended to a large number of O. ficus-indica cultivars. Copyright © 2013 Elsevier Ltd. All rights reserved.

On the influence of the culture conditions in bacterial antifouling bioassays and biofilm properties: Shewanella algae, a case study

PubMed Central

2014-01-01

Background A variety of conditions (culture media, inocula, incubation temperatures) are employed in antifouling tests with marine bacteria. Shewanella algae was selected as model organism to evaluate the effect of these parameters on: bacterial growth, biofilm formation, the activity of model antifoulants, and the development and nanomechanical properties of the biofilms. The main objectives were: 1) To highlight and quantify the effect of these conditions on relevant parameters for antifouling studies: biofilm morphology, thickness, roughness, surface coverage, elasticity and adhesion forces. 2) To establish and characterise in detail a biofilm model with a relevant marine strain. Results Both the medium and the temperature significantly influenced the total cell densities and biofilm biomasses in 24-hour cultures. Likewise, the IC50 of three antifouling standards (TBTO, tralopyril and zinc pyrithione) was significantly affected by the medium and the initial cell density. Four media (Marine Broth, MB; 2% NaCl Mueller-Hinton Broth, MH2; Luria Marine Broth, LMB; and Supplemented Artificial Seawater, SASW) were selected to explore their effect on the morphological and nanomechanical properties of 24-h biofilms. Two biofilm growth patterns were observed: a clear trend to vertical development, with varying thickness and surface coverage in MB, LMB and SASW, and a horizontal, relatively thin film in MH2. The Atomic Force Microscopy analysis showed the lowest Young modulii for MB (0.16 ± 0.10 MPa), followed by SASW (0.19 ± 0.09 MPa), LMB (0.22 ± 0.13 MPa) and MH2 (0.34 ± 0.16 MPa). Adhesion forces followed an inverted trend, being higher in MB (1.33 ± 0.38 nN) and lower in MH2 (0.73 ± 0.29 nN). Conclusions All the parameters significantly affected the ability of S. algae to grow and form biofilms, as well as the activity of antifouling molecules. A detailed study has been carried out in order to establish a biofilm model for further assays. The morphology and nanomechanics of S. algae biofilms were markedly influenced by the nutritional environments in which they were developed. As strategies for biofilm formation inhibition and biofilm detachment are of particular interest in antifouling research, the present findings also highlight the need for a careful selection of the assay conditions. PMID:24755232

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.

Simultaneous formation of multiscale hierarchical surface morphologies through sequential wrinkling and folding

NASA Astrophysics Data System (ADS)

Wang, Yu; Sun, Qingyang; Xiao, Jianliang

2018-02-01

Highly organized hierarchical surface morphologies possess various intriguing properties that could find important potential applications. In this paper, we demonstrate a facile approach to simultaneously form multiscale hierarchical surface morphologies through sequential wrinkling. This method combines surface wrinkling induced by thermal expansion and mechanical strain on a three-layer structure composed of an aluminum film, a hard Polydimethylsiloxane (PDMS) film, and a soft PDMS substrate. Deposition of the aluminum film on hard PDMS induces biaxial wrinkling due to thermal expansion mismatch, and recovering the prestrain in the soft PDMS substrate leads to wrinkling of the hard PDMS film. In total, three orders of wrinkling patterns form in this process, with wavelength and amplitude spanning 3 orders of magnitude in length scale. By increasing the prestrain in the soft PDMS substrate, a hierarchical wrinkling-folding structure was also obtained. This approach can be easily extended to other thin films for fabrication of multiscale hierarchical surface morphologies with potential applications in different areas.

Characterization of hematite nanoparticles synthesized via two different pathways

NASA Astrophysics Data System (ADS)

Das, Soumya; Hendry, M. Jim

2014-08-01

Hematite is one of the most common and thermodynamically stable iron oxides found in both natural and anthropogenic systems. Owing to its ubiquity, stability, moderate specific surface area, and ability to sequester metals and metalloids from aquatic systems, it has been the subject of a large number of adsorption studies published during the past few decades. Although preparation techniques are known to affect the surface morphology of hematite nanoparticles, the effects of aging under environmentally relevant conditions have yet to be tested with respect to surface morphology, surface area, and adsorptive capacity. We prepared hematite via two different pathways and aged it under highly alkaline conditions encountered in many mill tailings settings. Crystal habits and morphologies of the hematite nanoparticles were analyzed via scanning electron microscopy and transmission electron microscopy. X-ray diffraction, Raman spectroscopy, and Brunauer-Emmett-Teller surface area analyses were also conducted on the hematite nanoparticles before and after aging. The hematite synthesized via an Fe(III) salt solution (average particle size 37 nm) was morphologically and structurally different from the hematite synthesized via ferrihydrite aging (average particle size 144 nm). Overall, our data demonstrate that the crystallinity of hematite produced via ferrihydrite transformation is susceptible to morphological alterations/modifications. In contrast, the hematite formed via hydrolysis of an Fe(III) salt solution remains very stable in terms of structure, size, and morphology even under extreme experimental conditions.

Solid particle impingement erosion characteristics of cylindrical surfaces, pre-existing holes and slits

NASA Technical Reports Server (NTRS)

Rao, P. V.; Buckley, D. H.

1983-01-01

The erosion characteristics of aluminum cylinders sand-blasted with both spherical and angular erodent particles were studied and compared with results from previously studied flat surfaces. The cylindrical results are discussed with respect to impact conditions. The relationship between erosion rate and pit morphology (width, depth, and width to depth ratio) is established. The aspects of (1) erosion rate versus time curves on cylindrical surfaces; (2) long-term exposures; and (3) erosion rate versus time curves with spherical and angular particles are presented. The erosion morphology and characteristics of aluminum surfaces with pre-existing circular cylindrical and conical holes of different sizes were examined using weight loss measurements, scanning electron microscopy, a profilometer, and a depth gage. The morphological features (radial and concentric rings) are discussed with reference to flat surfaces, and the erosion features with spherical microglass beads. The similarities and differences of erosion and morphological features are highlighted. The erosion versus time curves of various shapes of holes are discussed and are compared with those of a flat surface. The erosion process at slits is considered.

Microsurgical anatomy of the human carotid body (glomus caroticum): Features of its detailed topography, syntopy and morphology.

PubMed

Schulz, Sissy-Amelie; Wöhler, Aliona; Beutner, Dirk; Angelov, Doychin N

2016-03-01

The human glomus caroticum (GC) is not readily accessible during ordinary anatomical teaching courses because of insufficient time and difficulties encountered in the preparation. Accordingly, most anatomical descriptions of its location, relationship to neighboring structures, size and shape are supported only by drawings, but not by photographs. The aim of this study is to present the GC with all associated roots and branches. Following microscope-assisted dissection and precise photo-documentation, a detailed analysis of location, syntopy and morphology was performed. We carried out this study on 46 bifurcations of the common carotid artery (CCA) into the external (ECA) and internal (ICA) carotid arteries and identified the GC in 40 (91%) of them. We found significant variations regarding the location of the GC and its syntopy: GC was associated with CCA (42%), ECA (28%) and ICA (30%) lying on the medial or lateral surface (82% or 13%, respectively) or exactly in the middle (5%) of the bifurcation. The short and long diameter of its oval form varied from 1.0 × 2.0 to 5.0 × 5.0mm. Connections with the sympathetic trunk (100%), glossopharyngeal (93%), vagus (79%) and hypoglossal nerve (90%) could be established in 29 cadavers. We conclude that precise knowledge of this enormous variety might be very helpful not only to students in medicine and dentistry during anatomical dissection courses, but also to surgeons working in this field. Copyright © 2015 Elsevier GmbH. All rights reserved.

Evaluating the use of drone photogrammetry for measurement of stream channel morphology and response to high flow events

NASA Astrophysics Data System (ADS)

Price, Katie; Ballow, William

2015-04-01

Traditional high-precision survey methods for stream channel measurement are labor-intensive and require wadeability or boat access to streams. These conditions limit the number of sites researchers are able to study and generally prohibit the possibility of repeat channel surveys to evaluate short-term fluctuations in channel morphology. In recent years, unmanned aerial vehicles (drones) equipped with photo and video capabilities have become widely available and affordable. Concurrently, developments in photogrammetric software offer unprecedented mapping and 3D rendering capabilities of drone-captured photography. In this study, we evaluate the potential use of drone-mounted cameras for detailed stream channel morphometric analysis. We used a relatively low-cost drone (DJI Phantom 2+ Vision) and commercially available, user friendly software (Agisoft Photscan) for photogrammetric analysis of drone-captured stream channel photography. Our test study was conducted on Proctor Creek, a highly responsive urban stream in Atlanta, Georgia, within the crystalline Piedmont region of the southeastern United States. As a baseline, we performed traditional high-precision survey methods to collect morphological measurements (e.g., bankfull and wetted width, bankfull and wetted thalweg depth) at 11 evenly-spaced transects, following USGS protocols along reaches of 20 times average channel width. We additionally used the drone to capture 200+ photos along the same reaches, concurrent with the channel survey. Using the photogrammetry software, we generated georeferenced 3D models of the stream channel, from which morphological measurements were derived from the 11 transects and compared with measurements from the traditional survey method. We additionally explored possibilities for novel morphometric characterization available from the continuous 3D surface, as an improvement on the limited number of detailed cross-sections available from standard methods. These results showed great promise for the drone photogrammetry methods, which encouraged the exploration of the possibility of repeat aerial surveys to evaluate channel response to high flow events. Repeat drone surveys were performed following a sequence of high-flow events in Proctor Creek to evaluate the possibility of using these methods for assessment of stream channel response to flooding.

Bubbles and Dust: Dissolution Rates of Unhydrated Volcanic Ash as a Function of Morphology, Composition, and Particle Size

NASA Astrophysics Data System (ADS)

Wygel, C. M.; Sahagian, D. L.

2017-12-01

Volcanic eruptions are natural hazards due to their explosive nature and widespread transportation and deposition of ash particles. After deposition and subsequent leaching in soils or water bodies, ash deposition positively (nutrients) and negatively (contaminants) impacts the health of flora and fauna, including humans. The effects of ash leachates have been difficult to replicate in field and laboratory studies due to the many complexities and differences between ash particles. Ash morphology is characteristic for each eruption, dependent upon eruption energy, and should play a critical role in determining leaching rates. Morphology reflects overall particle surface area, which is strongly influenced by the presence of surface dust. In addition, ash composition, which in part controls morphology and particle size, may also affect leaching rates. This study determines the extent to which ash morphology, surface area, composition, and particle size control ash dissolution rates. Further, it is necessary to determine whether compound vesicular ash particles permit water into their interior structures to understand if both the internal and external surface areas are available for leaching. To address this, six fresh, unhydrated ash samples from diverse volcanic environments and a large range in morphology, from Pele's spheres to vesicular compound ash, are tested in the laboratory. Ash morphology was characterized on the Scanning Electron Microscope (SEM) before and after leaching and surface area was quantified by Brunauer Emmett Teller (BET) analysis and with geometric calculations. Column Leachate Tests (CLT) were conducted to compare leaching rates over a range of basaltic to silicic ashes as a function of time and surface area, to recreate the effects of ash deposition in diverse volcanic environments. After the CLT, post-leaching water analyses were conducted by Ion Coupled Plasma-Mass Spectrometry (ICP-MS) and Ion Chromatography (IC). We find that leaching rates are correlated to characteristic surface area of ash particles.

Variable partitioning of flow and sediment transfer through a large river diffluence-confluence unit across a monsoonal flood pulse

NASA Astrophysics Data System (ADS)

Hackney, C. R.; Aalto, R. E.; Darby, S. E.; Parsons, D. R.; Leyland, J.; Nicholas, A. P.; Best, J.

2016-12-01

Bifurcations represent key morphological nodes within the channel networks of anabranching and braided fluvial channels, playing an important role in controlling local bed morphology, the routing of sediment and water, and defining the stability of the downstream reaches. Herein, we detail field observations of the three-dimensional flow structure, bed morphological changes and partitioning of both flow discharge and suspended sediment through a large diffluence-confluence unit on the Mekong River, Cambodia, across a range of flow stages (from 13,500 m3 s-1 to 27,000 m3 s-1) over the monsoonal flood-pulse cycle. We show that the discharge asymmetry (a measure of the disparity between discharges distributed down the left and right branches of the bifurcation) varies with flow discharge and that the influence of upstream curvature-induced cross-stream water surface slope and bed morphological changes are first-order controls in modulating the asymmetry in bifurcation discharge. Flow discharge is shown to play a key role in defining the morphodynamics of the diffluence-confluence unit downstream of the bifurcation. Our data show that during peak flows (Q 27,000 m3 s-1), the downstream island complex acts as a net sink of suspended sediment (with 2600 kg s-1 being deposited between the diffluence and confluence), whereas during lower flows, on both the rising and falling limbs of the flood wave, the sediment balance is in quasi-equilibrium. We propose a new conceptual model of bifurcation stability that incorporates varying flood discharge and in which the long term stability of the bifurcation, as well as the larger channel planform and morphology of the diffluence-confluence unit, are controlled by the variations in flood discharge.

The influence of flow discharge variations on the morphodynamics of a diffluence-confluence unit on the Mekong River

NASA Astrophysics Data System (ADS)

Hackney, Christopher; Darby, Stephen; Parsons, Daniel; Leyland, Julian; Aalto, Rolf; Nicholas, Andrew; Best, Jim

2017-04-01

Bifurcations represent key morphological nodes within the channel networks of anabranching and braided fluvial channels, playing an important role in controlling local bed morphology, the routing of sediment and water, and defining the stability of the downstream reaches. Herein, we detail field observations of the three-dimensional flow structure, bed morphological changes and partitioning of both flow discharge and suspended sediment through a large diffluence-confluence unit on the Mekong River, Cambodia, across a range of flow stages (from 13,500 m3 s-1 to 27,000 m3 s-1) over the monsoonal flood-pulse cycle. We show that the discharge asymmetry (a measure of the disparity between discharges distributed down the left and right branches of the bifurcation) varies with flow discharge and that the influence of upstream curvature-induced cross-stream water surface slope and bed morphological changes are first-order controls in modulating the asymmetry in bifurcation discharge. Flow discharge is shown to play a key role in defining the morphodynamics of the diffluence-confluence unit downstream of the bifurcation. Our data show that during high flows (Q 27,000 m3 s-1), the downstream island complex acts as a net sink of suspended sediment (with 2600 kg s-1 being deposited between the diffluence and confluence), whereas during lower flows, on both the rising and falling limbs of the flood wave, the sediment balance is in quasi-equilibrium. We propose, therefore, that the long term stability of the bifurcation, as well as the larger channel planform and morphology of the diffluence-confluence unit, is therefore controlled by annual monsoonal flood pulses and the associated variations in discharge.

Influence of surface morphology on adsorption of potassium stearate molecules on diamond-like carbon substrate: A molecular dynamics study

NASA Astrophysics Data System (ADS)

Guo, Shusen; Cao, Yongzhi; Sun, Tao; Zhang, Junjie; Gu, Le; Zhang, Chuanwei; Xu, Zhiqiang

2018-05-01

Molecular dynamics (MD) simulations were used to provide insights into the influence of nano-scale surface morphology on adsorptive behavior of Potassium stearate molecules on diamond-like carbon (DLC) substrates. Particular focus was given to explain that how the distinctive geometric properties of different surface morphologies affect the equilibrium structures and substrate-molecules interactions of monolayers, which was achieved through adsorptive analysis methods including adsorptive process, density profile, density distribution and surface potential energy. Analysis on surface potential energy demonstrated that the adsorptivity of amorphous smooth substrate is uniformly distributed over the surface, while DLC substrates with different surface morphologies appear to be more potentially corrugated, which improves the adsorptivity significantly. Because of the large distance of molecules from carbon atoms located at the square groove bottom, substrate-molecules interactions vanish significantly, and thus potassium stearate molecules cannot penetrate completely into the square groove. It can be observed that the equilibrium substrate-molecules interactions of triangle groove and semi-circle groove are much more powerful than that of square groove due to geometrically advantageous properties. These findings provided key information of optimally design of solid substrates with controllable adsorptivity.

Morphological diversity and function of the stigma in Ficus species (Moraceae)

NASA Astrophysics Data System (ADS)

Teixeira, Simone Pádua; Costa, Marina F. B.; Basso-Alves, João Paulo; Kjellberg, Finn; Pereira, Rodrigo A. S.

2018-07-01

The stigma plays several roles such as pollen hydration and selection, and pollen tube nutrition. In the Ficus-fig wasp mutualism, stigmata have an additional, almost unknown, function by representing a physical interface for both plant and wasp reproduction. We used light and electron microscopy to compare the detailed morphology of the stigmata of nine Ficus species of different sections and with different pollination modes and sexual expressions. Figs were collected at the stage when the stigmata were receptive for pollination. Stigmata in actively pollinated monoecious species have well developed papillae concentrated on the adaxial surface exposed towards the fig cavity. Conversely, the passively pollinated monoecious species have the whole surface of the stigmata covered by somewhat smaller papillae. In both actively and passively pollinated monoecious species these features are consistent, irrespective of style length. In all actively pollinated gynodioecious species, the stigmata of pistillate flowers were tubular or infundibuliform whereas in almost all actively pollinated monoecious species (except F. racemosa) the stigmata were filiform, with one branch or two asymmetric branches. In gynodioecious species the short-styled flowers in "male" figs show a limited receptive surface with small papillae, while the stigmata of long-styled flowers in "female" figs are covered by papillae that extend down the sides of the style, increasing the stigmatic surface. In actively pollinated species, stigmata are cohesive, forming a common surface for pollen tube germination (= synstigma). The synstigma arrangement was quite variable: lax, cohesive or very cohesive, with entanglement by stigmatic papillae and stylar trichomes. Entanglement by stylar trichomes is common in gynodioecious species. The synstigma arrangement did not correlate with phylogeny or breeding system. This study is the first to report a very loose synstigma in actively pollinated monoecious Ficus species. Our analyses revealed that, in Ficus, the synstigma is functionally analogous to an extra-gynoecial compitum. Comparative studies will be required to test further hypotheses about the evolutionary determinants of such variation.

Morphology of the last subaerial unconformity on a shelf: insights into transgressive ravinement and incised valley occurrence in the Gulf of Cádiz

NASA Astrophysics Data System (ADS)

Lobo, F. J.; García, M.; Luján, M.; Mendes, I.; Reguera, M. I.; Van Rooij, D.

2018-02-01

The main aim of this study is to explore the spatial patterns of the shelf-scale erosional unconformity related to the last glacial maximum (LGM), particularly in terms of the role of underlying geology and the presumed primary influence of sea-level changes. This involved a detailed mapping of the most recent and widespread erosional shelf surface in a sector of the northern margin of the Gulf of Cádiz (northeast Atlantic Ocean) located adjacent to a major fluvial source. A dense network of high-resolution seismic profiles collected in the 1990s and 2013 off the Guadiana River revealed two distinct geomorphological domains on the LGM shelf-scale subaerial surface. The outer domain exhibits a widespread occurrence of erosional truncations, with a rugged, erosional pattern over the most distal shelf setting that evolves landward into a planar unconformity. The inner domain is more extensive and is characterized by the common occurrence of highly reflective, localized mounded seismic facies that laterally evolve into an irregular surface and in places may develop a channelized morphology. Significant fluvial incision is limited to a major straight valley and a secondary distributary channel. A distinct partition of the lowstand surface is documented, and attributed to a well-marked lithological change. A coarse-grained inner shelf comprises underlying lithified coastal deposits, whereas a fine-grained outer shelf is regarded as the uppermost expression of regressive prodeltaic wedges. The influence of regional indurated surfaces is also expressed in (1) the pattern of erosion, this being more patchy on the inner shelf due to lateral changes of erodibility, whereas on the outer shelf it shows laterally continuous bands, owing to different modes of transgressive ravinement; (2) the spatial and temporal variability of fluvial incision. Inner shelf armoring by indurated deposits prevents reoccupation of previously incised valleys.

Atomic Oxygen (ATOX) simulation of Teflon FEP and Kapton H surfaces using a high intensity, low energy, mass selected, ion beam facility

NASA Technical Reports Server (NTRS)

Vered, R.; Grossman, E.; Lempert, G. D.; Lifshitz, Y.

1994-01-01

A high intensity (greater than 10(exp 15) ions/sq cm) low energy (down to 5 eV) mass selected ion beam (MSIB) facility was used to study the effects of ATOX on two polymers commonly used for space applications (Kapton H and Teflon FEP). The polymers were exposed to O(+) and Ne(+) fluences on 10(exp 15) - 10(exp 19) ions/sq cm, using 30eV ions. A variety of analytical methods were used to analyze the eroded surfaces including: (1) atomic force microscopy (AFM) for morphology measurements; (2) total mass loss measurements using a microbalance; (3) surface chemical composition using x-ray photoelectron spectroscopy (XPS), and (4) residual gas analysis (RGA) of the released gases during bombardment. The relative significance of the collisional and chemical degradation processes was evaluated by comparing the effects of Ne(+) and O(+) bombardment. For 30 eV ions it was found that the Kapton is eroded via chemical mechanisms while Teflon FEP is eroded via collisional mechanisms. AFM analysis was found very powerful in revealing the evolution of the damage from its initial atomic scale (roughness of approx. 1 nm) to its final microscopic scale (roughness greater than 1 micron). Both the surface morphology and the average roughness of the bombarded surfaces (averaged over 1 micron x 1 micron images by the system's computer) were determined for each sample. For 30 eV a non linear increase of the Kapton roughness with the O(+) fluence was discovered (a slow increase rate for fluences phi less than 5 x 10(exp 17) O(+)/sq cm, and a rapid increase rate for phi greater than 5 x 10(exp 17) O(+)/sq cm). Comparative studies on the same materials exposed to RF and DC oxygen plasmas indicate that the specific details of the erosion depend on the simulation facility emphasizing the advantages of the ion beam facility.

The complete larval development of the mud shrimp Upogebia vasquezi (Gebiidea: Upogebiidae) reared in the laboratory.

PubMed

De Oliveira, Danielly Brito; Martinelli-Lemos, Jussara Moretto; Abrunhosa, Fernando Araújo

2014-07-01

The larval development of Upogebia vasquezi consists of four zoeal stages and a megalopa. In the present study, each larval stage was described and illustrated in detail. The first two stages are re-described in order to provide a detailed comparison with the data available for this species recorded in a previous study. The morphological features of all the stages are compared with those of the larvae of other Upogebia species reported previously in the literature. Broad morphological similarities and distinctions were found among most Upogebia species. The main interspecific variations in the morphology of the zoeal stages are the segmentation pattern of the antennular endopod and number of aesthetascs, the number of setae on the scaphognathite and the presence or absence of a mandibular palp.

Ag films deposited on Si and Ti: How the film-substrate interaction influences the nanoscale film morphology

NASA Astrophysics Data System (ADS)

Ruffino, F.; Torrisi, V.

2017-11-01

Submicron-thick Ag films were sputter deposited, at room temperature, on Si, covered by the native SiO2 layer, and on Ti, covered by the native TiO2 layer, under normal and oblique deposition angle. The aim of this work was to study the morphological differences in the grown Ag films on the two substrates when fixed all the other deposition parameters. In fact, the surface diffusivity of the Ag adatoms is different on the two substrates (higher on the SiO2 surface) due to the different Ag-SiO2 and Ag-TiO2 atomic interactions. So, the effect of the adatoms surface diffusivity, as determined by the adatoms-substrate interaction, on the final film morphology was analyzed. To this end, microscopic analyses were used to study the morphology of the grown Ag films. Even if the homologous temperature prescribes that the Ag film grows on both substrates in the zone I described by the structure zone model some significant differences are observed on the basis of the supporting substrate. In the normal incidence condition, on the SiO2/Si surface a dense close-packed Ag film exhibiting a smooth surface is obtained, while on the TiO2/Ti surface a more columnar film morphology is formed. In the oblique incidence condition the columnar morphology for the Ag film occurs both on SiO2/Si and TiO2/Ti but a higher porous columnar film is obtained on TiO2/Ti due to the lower Ag diffusivity. These results indicate that the adatoms diffusivity on the substrate as determined by the adatom-surface interaction (in addition to the substrate temperature) strongly determines the final film nanostructure.

A kinetic model for the characteristic surface morphologies of thin films by directional vapor deposition

NASA Astrophysics Data System (ADS)

Li, Kun-Dar; Huang, Po-Yu

2017-12-01

In order to simulate a process of directional vapor deposition, in this study, a numerical approach was applied to model the growth and evolution of surface morphologies for the crystallographic structures of thin films. The critical factors affecting the surface morphologies in a deposition process, such as the crystallographic symmetry, anisotropic interfacial energy, shadowing effect, and deposition rate, were all enclosed in the theoretical model. By altering the parameters of crystallographic symmetry in the structures, the faceted nano-columns with rectangular and hexagonal shapes were established in the simulation results. Furthermore, for revealing the influences of the anisotropic strength and the deposition rate theoretically on the crystallographic structure formations, various parameters adjusted in the numerical calculations were also investigated. Not only the morphologies but also the surface roughnesses for different processing conditions were distinctly demonstrated with the quantitative analysis of the simulations.

Surface morphology and electrochemical studies on polyaniline/CuO nano composites

NASA Astrophysics Data System (ADS)

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

2018-05-01

An electrochemically synthesized Polyaniline (PANI) and Polyaniline/copper oxide (PCN) nano composite have studied the morphology and electrochemical properties. The composite is characterized by X-ray diffraction (XRD) and surface morphology was studied using FESEM and electrochemical behavior is studied using cyclic voltammetry (CV) technique. The CV curves shows rectangular shaped curve and they have contribution to electrical double layer capacitance (EDCL).

Morphological instability of GaAs (7 1 1)A: A transition between (1 0 0) and (5 1 1) terraces

NASA Astrophysics Data System (ADS)

Yazdanpanah, V. R.; Wang, Zh. M.; Salamo, G. J.

2005-06-01

We report on the use of reflection high-energy electron diffraction (RHEED) and scanning tunneling microscopy (STM) study that indicates that the GaAs (7 1 1)A is right at the transition between vicinal GaAs (1 0 0) and vicinal GaAs (5 1 1)A surfaces and that a variation of the As overpressure switches the surface morphology between the two vicinal surfaces. The steps on the vicinal (1 0 0) surface have a width of 1.5 nm creating a staircase surface with excellent possibilities for growth of quantum wells. As-rich conditions can be described by vicinal (5 1 1)A surfaces with a width of 3.5 nm. This surface could find applications as a template for quantum wire growth. The observation suggests that the transition between these two morphologies is understandable based on the increase in surface energy of a vicinal (1 0 0) surface as the step separation approaches the dimer reconstructed separation.

A comparative study of the properties of five-layered Aurivillius oxides A2Bi4Ti5O18 (A = Ba, Pb, and Sr) synthesized by different wet chemical routes

NASA Astrophysics Data System (ADS)

Dubey, Shivangi; Subohi, Oroosa; Kurchania, Rajnish

2018-07-01

This paper reports the detailed study of the effect of different wet chemical synthesis routes (solution combustion, co-precipitation, and sol-gel route) on the microstructure, phase formation, dielectric, electrical, and ferroelectric properties of five-layered Aurivillius oxides: A2Bi4Ti5O18 (A = Ba, Pb, and Sr). Different synthesis parameters like the precursors used, synthesis temperature, and reaction time affects the morphology of the ceramics. Microstructure in turn influences the dielectric and ferroelectric properties. It was observed that the sol-gel-synthesized ceramics possess higher dielectric constant and remanent polarization, low dielectric loss due to lower conductivity in these samples as a result of higher density in these compounds as compared to those synthesized by other wet chemical synthesis routes such as solution combustion route and co-precipitation technique. The XRD data are used for phase analysis and surface morphology is studied using SEM images. Dielectric and electrical properties are investigated as a function of frequency and temperature.

Fabrication of GaN doped ZnO nanocrystallines by laser ablation.

PubMed

Gopalakrishnan, N; Shin, B C; Bhuvana, K P; Elanchezhiyan, J; Balasubramanian, T

2008-08-01

Here, we present the fabrication of pure and GaN doped ZnO nanocrystallines on Si(111) substrates by KrF excimer laser. The targets for the ablation have been prepared by conventional ceramic method. The fabricated nanocrystallines have been investigated by X-ray diffraction, photoluminescence and atomic force microscopy. The X-ray diffraction analysis shows that the crystalline size of pure ZnO is 36 nm and it is 41 nm while doped with 0.8 mol% of GaN due to best stoichiometry between Zn and O. Photoluminescence studies reveal that intense deep level emissions have been observed for pure ZnO and it has been suppressed for the GaN doped ZnO structures. The images of atomic force microscope show that the rms surface roughness is 27 nm for pure ZnO and the morphology is improved with decrease in rms roughness, 18 nm with fine crystallines while doped with 1 mol% GaN. The improved structural, optical and morphological properties of ZnO nanocrystalline due to GaN dopant have been discussed in detail.

Impact of coastal forcing and groundwater recharge on the growth of a fresh groundwater lens in a mega-scale beach nourishment

NASA Astrophysics Data System (ADS)

Huizer, Sebastian; Radermacher, Max; de Vries, Sierd; Oude Essink, Gualbert H. P.; Bierkens, Marc F. P.

2018-02-01

For a large beach nourishment called the Sand Engine - constructed in 2011 at the Dutch coast - we have examined the impact of coastal forcing (i.e. natural processes that drive coastal hydro- and morphodynamics) and groundwater recharge on the growth of a fresh groundwater lens between 2011 and 2016. Measurements of the morphological change and the tidal dynamics at the study site were incorporated in a calibrated three-dimensional and variable-density groundwater model of the study area. Simulations with this model showed that the detailed incorporation of both the local hydro- and morphodynamics and the actual recharge rate can result in a reliable reconstruction of the growth in fresh groundwater resources. In contrast, the neglect of tidal dynamics, land-surface inundations, and morphological changes in model simulations can result in considerable overestimations of the volume of fresh groundwater. In particular, wave runup and coinciding coastal erosion during storm surges limit the growth in fresh groundwater resources in dynamic coastal environments, and should be considered at potential nourishment sites to delineate the area that is vulnerable to salinization.

Interface morphology of a Cr(001)/Fe(001) superlattice determined by scanning tunneling microscopy and x-ray diffraction: A comparison

NASA Astrophysics Data System (ADS)

Schmidt, C. M.; Bürgler, D. E.; Schaller, D. M.; Meisinger, F.; Güntherodt, H.-J.; Temst, K.

2001-01-01

A Cr(001)/Fe(001) superlattice with ten bilayers grown by molecular beam epitaxy on a Ag(001) substrate is studied by in situ scanning tunneling microscopy (STM) and ex situ x-ray diffraction (XRD). Layer-resolved roughness parameters determined from STM images taken in various stages of the superlattice fabrication are compared with average values reported in the literature or obtained from the fits of our XRD data. Good agreement is found for the rms roughnesses describing vertical roughness and for the lateral correlation lengths characterizing correlated as well as uncorrelated interface roughness if peculiarities of STM and XRD are taken into account. We discuss in detail (i) the possible differences between the STM topography of a free surface and the morphology of a subsequently formed interface, (ii) contributions due to chemical intermixing at the interfaces, (iii) the comparison of XRD parameters averaged over all interfaces versus layer-resolved STM parameters, and (iv) the question of the coherent field of view for the determination of rms values.

Synthesis of Hexagonal Boron Nitride Mono layer: Control of Nucleation and Crystal Morphology

DOE PAGES

Stehle, Yijing Y.; Meyer, III, Harry M.; Unocic, Raymond R.; ...

2015-11-10

Mono layer hexagonal boron nitride (hBN) attracts significant attention due to the potential to be used as a complementary two-dimensional dielectric in fabrication of functional 2D heterostructures. Here we investigate the growth stages of the hBN single crystals and show that hBN crystals change their shape from triangular to truncated triangular and further to hexagonal depending on copper substrate distance from the precursor. We suggest that the observed hBN crystal shape variation is affected by the ratio of boron to nitrogen active species concentrations on the copper surface inside the CVD reactor. Strong temperature dependence reveals the activation energies formore » the hBN nucleation process of similar to 5 eV and crystal growth of similar to 3.5 eV. We also show that the resulting h-BN film morphology is strongly affected by the heating method of borazane precursor and the buffer gas. Elucidation of these details facilitated synthesis of high quality large area monolayer hexagonal boron nitride by atmospheric pressure chemical vapor deposition on copper using borazane as a precursor.« less

Morphology-dependent photo-induced polarization recovery in ferroelectric thin films

NASA Astrophysics Data System (ADS)

Wang, J. Y.; Liu, G.; Sando, D.; Nagarajan, V.; Seidel, J.

2017-08-01

We investigate photo-induced ferroelectric domain switching in a series of Pb(Zr0.2Ti0.8)O3/La0.7Sr0.3MnO3 (PZT/LSMO) bilayer thin films with varying surface morphologies by piezoresponse force microscopy under light illumination. We demonstrate that reverse poled ferroelectric regions can be almost fully recovered under laser irradiation of the PZT layer and that the recovery process is dependent on the surface morphology on the nanometer scale. The recovery process is well described by the Kolmogorov-Avrami-Ishibashi model, and the evolution speed is controlled by light intensity, sample thickness, and initial write voltage. Our findings shed light on optical control of the domain structure in ferroelectric thin films with different surface morphologies.

Slip-additive migration, surface morphology, and performance on injection moulded high-density polyethylene closures.

PubMed

Dulal, Nabeen; Shanks, Robert; Gengenbach, Thomas; Gill, Harsharn; Chalmers, David; Adhikari, Benu; Pardo Martinez, Isaac

2017-11-01

The amount and distribution of slip agents, erucamide, and behenamide, on the surface of high-density polyethene, is determined by integral characteristics of slip agent structure and polymer morphology. A suite of surface analysis techniques was applied to correlate physicochemical properties with slip-additive migration behaviour and their surface morphology. The migration, surface morphology and physicochemical properties of the slip additives, crystallinity and orientation of polyethene spherulites and interaction between slip additives and high-density polyethene influence the surface characteristics. The high-density polyethene closures were produced with erucamide and behenamide separately and stored until they produced required torque. Surface composition was determined employing spectroscopy and gas chromatography. The distribution of additives was observed under optical, scanning electron and atomic force microscopes. The surface energy, crystallinity and application torque were measured using contact angle, differential scanning calorimeter and a torque force tester respectively. Each slip additive produced a characteristic amide peak at 1645cm -1 in infrared spectroscopy and peaks of oxygen and nitrogen in X-ray photoelectron spectroscopy, suggesting their presence on the surface. The erucamide produced placoid scale-like structures and behenamide formed denticulate structures. The surface erucamide and behenamide responsible for reducing the torque was found to be 15.7µg/cm 2 and 1.7µg/cm 2 . Copyright © 2017 Elsevier Inc. All rights reserved.

Analysis of an evaporitic dome in eastern Tithonium Chasma (Mars): the result of diapirism processes?

NASA Astrophysics Data System (ADS)

Davide, Baioni; Forese Carlo, Wezel

2010-05-01

The Tithonium Chasma (TC) is the northern trench of the western troughs of Valles Marineris (Mars). In the easternmost part of the canyon system a mountain displaying dome shape morphology is located. The mineralogical characteristics of the dome have been indicated by the OMEGA image spectrometer data that mapped it as a sulphate deposit (OMEGA data orbit 531_3). Studies on the spectral characteristic absorptions for the hydrated magnesium sulphates carried out on the deposits within the Tithonium Chasma, showed the mineralogical components displayed by the dome in detail. According to these results the dome shows clear signatures of kieserite (Mg SO4.H2O), an evaporitic mineral also found on the Earth. Further studies carried out on the characteristics and the genesis of Kieserite both on Mars and on the Earth showed that the dome can not be constituted entirely by kieserite alone but probably it might be constituted also by the same salts that on the Earth alter to kieserite, such as, carnallite, kainite and halite. In this work we investigated in great detail the surface features of the dome located in the eastern part of TC, with the aim to try to determine its nature and origin. The morphological features of the dome have been investigated through the integrate analysis of HiRISE, HRSC, MOC and THEMIS data, while the morphometric characteristics have been measured on a topographic map (50 m contours lines) built using HRSC and MOLA data. The observation of the dome surface highlights features created by fluvio-erosional and solutional processes. The dome appears to be characterized by deep gully morphology displaying a radial system that develops from the margins of the summit plateau. The solutional surface is characterized by landforms typical of the karst morphology such as, karren, dolines and collapse dolines. Depositional forms displaying periglacial rock glacier features can be seen at the foot of the slopes, while they seem to be lacking along the dome flanks. The observation made also highlights the presence of layers outcropping on the surface of the dome. The layers display both laterally and vertically continuity apparently without facies variations. The dome seems to be formed of different materials (minerals, grain-size) with different properties. The analysis performed show that the landforms observed clearly indicate the presence of solutional processes that seem to have worked in a selective way. These landforms indicate the presence of liquid water, probably caused by the melting of ice in a periglacial environment, or permafrost rich soil, suggesting that either the material is ice-rich or was so at one time. Deposits similar to that one located in the eastern TC are found almost in all chasmata of Valles Marineris system and are well known as interior layered deposits(ILD). To explain the origin and formation mechanisms of the ILD several hypotheses have been formulated in previous studies. The results carried out in this study allow us to suppose that any of the previous hypotheses to explain its origin is fitting with the evidences found. In our opinion the data observed show evidences that allow us to suppose that the dome located in the eastern part of TC might represents the result of diapirism processes.

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.

Exploration of the Moon with Remote Sensing, Ground-Penetrating Radar, and the Regolith-Evolved Gas Analyzer (REGA)

NASA Technical Reports Server (NTRS)

Cooper, B. L.; Hoffman, J. H.; Allen, Carlton C.; McKay, David S.

1998-01-01

There are two important reasons to explore the Moon. First, we would like to know more about the Moon itself: its history, its geology, its chemistry, and its diversity. Second, we would like to apply this knowledge to a useful purpose. namely finding and using lunar resources. As a result of the recent Clementine and Lunar Prospector missions, we now have global data on the regional surface mineralogy of the Moon, and we have good reason to believe that water exists in the lunar polar regions. However, there is still very little information about the subsurface. If we wish to go to the lunar polar regions to extract water, or if we wish to go anywhere else on the Moon and extract (or learn) anything at all, we need information in three dimensions an understanding of what lies below the surface, both shallow and deep. The terrestrial mining industry provides an example of the logical steps that lead to an understanding of where resources are located and their economic significance. Surface maps are examined to determine likely locations for detailed study. Geochemical soil sample surveys, using broad or narrow grid patterns, are then used to gather additional data. Next, a detailed surface map is developed for a selected area, along with an interpretation of the subsurface structure that would give rise to the observed features. After that, further sampling and geophysical exploration are used to validate and refine the original interpretation, as well as to make further exploration/ mining decisions. Integrating remotely sensed, geophysical, and sample datasets gives the maximum likelihood of a correct interpretation of the subsurface geology and surface morphology. Apollo-era geophysical and automated sampling experiments sought to look beyond the upper few microns of the lunar surface. These experiments, including ground-penetrating radar and spectrometry, proved the usefulness of these methods for determining the best sites for lunar bases and lunar mining operations.

Response of Quiescent Cerebral Cortical Astrocytes to Nanofibrillar Scaffold Properties

NASA Astrophysics Data System (ADS)

Ayres, Virginia; Mujdat Tiryaki, Volkan; Xie, Kan; Ahmed, Ijaz; Shreiber, David I.

2013-03-01

We present results of an investigation to examine the hypothesis that the extracellular environment can trigger specific signaling cascades with morphological consequences. Differences in the morphological responses of quiescent cerebral cortical astrocytes cultured on the nanofibrillar matrices versus poly-L-lysine functionalized glass and Aclar, and unfunctionalized Aclar surfaces were demonstrated using atomic force microscopy (AFM) and phalloidin staining of F-actin. The differences and similarities of the morphological responses were consistent with differences and similarities of the surface polarity and surface roughness of the four surfaces investigated in this work, characterized using contact angle and AFM measurements. The three-dimensional capability of AFM was also used to identify differences in cell spreading. An initial quantitative immunolabeling study further identified significant differences in the activation of the Rho GTPases: Cdc42, Rac1, and RhoA, which are upstream regulators of the observed morphological responses: filopodia, lamellipodia, and stress fiber formation. The results support the hypothesis that the extracellular environment can trigger preferential activation of members of the Rho GTPase family with demonstrable morphological consequences for cerebral cortical astrocytes. The support of NSF PHY-095776 is acknowledged.

Dental Implant Systems

PubMed Central

Oshida, Yoshiki; Tuna, Elif B.; Aktören, Oya; Gençay, Koray

2010-01-01

Among various dental materials and their successful applications, a dental implant is a good example of the integrated system of science and technology involved in multiple disciplines including surface chemistry and physics, biomechanics, from macro-scale to nano-scale manufacturing technologies and surface engineering. As many other dental materials and devices, there are crucial requirements taken upon on dental implants systems, since surface of dental implants is directly in contact with vital hard/soft tissue and is subjected to chemical as well as mechanical bio-environments. Such requirements should, at least, include biological compatibility, mechanical compatibility, and morphological compatibility to surrounding vital tissues. In this review, based on carefully selected about 500 published articles, these requirements plus MRI compatibility are firstly reviewed, followed by surface texturing methods in details. Normally dental implants are placed to lost tooth/teeth location(s) in adult patients whose skeleton and bony growth have already completed. However, there are some controversial issues for placing dental implants in growing patients. This point has been, in most of dental articles, overlooked. This review, therefore, throws a deliberate sight on this point. Concluding this review, we are proposing a novel implant system that integrates materials science and up-dated surface technology to improve dental implant systems exhibiting bio- and mechano-functionalities. PMID:20480036

Crystal morphology of sunflower wax in soybean oil organogel

USDA-ARS?s Scientific Manuscript database

While sunflower wax has been recognized as an excellent organogelator for edible oil, the detailed morphology of sunflower wax crystals formed in an edible oil organogel has not been fully understood. In this study, polarized light microscopy, phase contrast microscopy, scanning electron microscopy ...

Visualization of chorioretinal vasculature in mice in vivo using a combined OCT/SLO imaging system

NASA Astrophysics Data System (ADS)

Goswami, Mayank; Zhang, Pengfei; Pugh, Edward N.; Zawadzki, Robert J.

2016-03-01

Chorioretinal blood vessel morphology in mice is of great interest to researchers studying eye disease mechanisms in animal models. Two leading retinal imaging modalities -- Optical Coherence Tomography (OCT) and Scanning Laser Ophthalmoscopy (SLO) -- have offered much insight into vascular morphology and blood flow. OCT "flow-contrast" methods have provided detailed mapping of vascular morphology with micrometer depth resolution, while OCT Doppler methods have enabled the measurement of local flow velocities. SLO remains indispensable in studying blood leakage, microaneurysms, and the clearance time of contrast agents of different sizes. In this manuscript we present results obtained with a custom OCT/SLO system applied to visualize the chorioretinal vascular morphology of pigmented C57Bl/6J and albino nude (Nu/Nu) mice. Blood perfusion maps of choroidal vessels and choricapillaris created by OCT and SLO are presented, along with detailed evaluation of different OCT imaging parameters, including the use of the scattering contrast agent Intralipid. Future applications are discussed.

Functional morphology of parasitic isopods: understanding morphological adaptations of attachment and feeding structures in Nerocila as a pre-requisite for reconstructing the evolution of Cymothoidae.

PubMed

Nagler, Christina; Haug, Joachim T

2016-01-01

Parasites significantly influence food webs and ecosystems and occur all over the world in almost every animal group. Within crustaceans there are numerous examples of ectoparasites; for example, representatives of the isopod group Cymothoidae. These obligatory parasitic isopods are relatively poorly studied regarding their functional morphology. Here we present new details of the morphological adaptations to parasitism of the cymothoiid ingroup Nerocila with up-to-date imaging methods (macro photography, stereo imaging, fluorescence photography, micro CT, and histology). Central aspects of the study were (1) the morphology of the mouthparts and (2) the attachment on the host, hence the morphology of the thoracopods. The mouthparts (labrum, mandibles, paragnaths, maxillulae, maxillae, maxillipeds) form a distinct mouth cone and are most likely used for true sucking. The mouthparts are tightly "folded" around each other and provide functional rails for the only two moving mouthparts, mandible and maxillula. Both are not moving in an ancestral-type median-lateral movement, but are strongly tilted to move more in a proximal-distal axis. New details concerning the attachment demonstrate that the angular arrangement of the thoracopods is differentiated to impede removal by the host. The increased understanding of morphological adaptation to parasitism of modern forms will be useful in identifying disarticulated (not attached to the host) fossil parasites.

Functional morphology of parasitic isopods: understanding morphological adaptations of attachment and feeding structures in Nerocila as a pre-requisite for reconstructing the evolution of Cymothoidae

PubMed Central

Haug, Joachim T.

2016-01-01

Parasites significantly influence food webs and ecosystems and occur all over the world in almost every animal group. Within crustaceans there are numerous examples of ectoparasites; for example, representatives of the isopod group Cymothoidae. These obligatory parasitic isopods are relatively poorly studied regarding their functional morphology. Here we present new details of the morphological adaptations to parasitism of the cymothoiid ingroup Nerocila with up-to-date imaging methods (macro photography, stereo imaging, fluorescence photography, micro CT, and histology). Central aspects of the study were (1) the morphology of the mouthparts and (2) the attachment on the host, hence the morphology of the thoracopods. The mouthparts (labrum, mandibles, paragnaths, maxillulae, maxillae, maxillipeds) form a distinct mouth cone and are most likely used for true sucking. The mouthparts are tightly “folded” around each other and provide functional rails for the only two moving mouthparts, mandible and maxillula. Both are not moving in an ancestral-type median-lateral movement, but are strongly tilted to move more in a proximal-distal axis. New details concerning the attachment demonstrate that the angular arrangement of the thoracopods is differentiated to impede removal by the host. The increased understanding of morphological adaptation to parasitism of modern forms will be useful in identifying disarticulated (not attached to the host) fossil parasites. PMID:27441121

Does Sexual Selection Influence Ornamentation of Hemipenes in Old World Snakes?

PubMed

Andonov, Kostadin; Natchev, Nikolay; Kornilev, Yurii V; Tzankov, Nikolay

2017-09-01

In the present study, we investigated and documented the morphology of the male copulatory organs (hemipenes) in fifteen wide-ranging snake species. The species represent four families (Boidae, Colubridae, Lamprophiidae, and Viperidae) and ten genera. We applied the same preparation techniques for all species, successfully everting and expanding the organs completely. The detailed description of the general morphology of the male copulatory organs was based on 31 specimens. Our data were compared with published observations and we point out some incorrectly described details in previous investigations. We provide the first description of the hemipenial morphology for three ophidian species (Elaphe sauromates, Telescopus fallax, and Malpolon insignitus). In addition to the morphological characteristics of the hemipenes presented in the research, we propose the adoption of a standardized index describing the hemipenial proportions. The immense variation in hemipenial morphology presupposes its dynamic evolution, but we suggest that many of the significant structures observed here may have escaped previous researchers due to differing methodologies. Some of the highly ornamented morphologies that we describe are consistent with a locking mechanism during copulation. However, other morphologies may relate to the variety of mating behaviors observed. As a result, we propose that sexual selection is the major driver affecting the hemipenial ornamentation in snakes. Anat Rec, 300:1680-1694, 2017. © 2017 Wiley Periodicals, Inc. © 2017 Wiley Periodicals, Inc.

The land morphology approach to flood risk mapping: An application to Portugal.

PubMed

Cunha, N S; Magalhães, M R; Domingos, T; Abreu, M M; Küpfer, C

2017-05-15

In the last decades, the increasing vulnerability of floodplains is linked to societal changes such as population density growth, land use changes, water use patterns, among other factors. Land morphology directly influences surface water flow, transport of sediments, soil genesis, local climate and vegetation distribution. Therefore, the land morphology, the land used and management directly influences flood risks genesis. However, attention is not always given to the underlying geomorphological and ecological processes that influence the dynamic of rivers and their floodplains. Floodplains are considered a part of a larger system called Wet System (WS). The WS includes permanent and temporary streams, water bodies, wetlands and valley bottoms. Valley bottom is a broad concept which comprehends not only floodplains but also flat and concave areas, contiguous to streams, in which slope is less than 5%. This will be addressed through a consistent method based on a land morphology approach that classifies landforms according to their hydrological position in the watershed. This method is based on flat areas (slopes less than 5%), surface curvature and hydrological features. The comparison between WS and flood risk data from the Portuguese Environmental Agency for the main rivers of mainland Portugal showed that in downstream areas of watersheds, valley bottoms are coincident with floodplains modelled by hydrological methods. Mapping WS has a particular interest in analysing river ecosystems position and function in the landscape, from upstream to downstream areas in the watershed. This morphological approach is less demanding data and time-consuming than hydrological methods and can be used as the preliminary delimitation of floodplains and potential flood risk areas in situations where there is no hydrological data available. The results were also compared with the land use/cover map at a national level and detailed in Trancão river basin, located in Lisbon metropolitan area, an urbanized basin that suffered heavy flooding in the last decades. This study also contributes to a better understanding of the basin morphology at a local-scale and the effects of soil sealing in downstream flood risks. This work will contribute to the understanding of the morphology, ecology and land use of watersheds that could be used to reduce runoff and downstream flood risk. This can be accomplished by using natural water retention and infiltration methods or higher-level based planning instead of a reaction to local decisions on flood hazards. This morphological approach to map landforms, including wet system, is a valuable tool to assist policy makers and planners in flood risk and land use management, floodplain restoration, agricultural land management practices, and location of human activities according to ecological suitability. Copyright © 2017 Elsevier Ltd. All rights reserved.

Morphology of jack pine and tamarack needles in dense stands.

Treesearch

Terry F. Strong; J. Zavitkovski

1978-01-01

Effects of position in the crown on needle morphology and surface area were studied. Needle length, surface area, and dry weight increased and specific needs area decreased from the lower to the upper third of the crown.

Surface modifications induced by pulsed-laser texturing—Influence of laser impact on the surface properties

NASA Astrophysics Data System (ADS)

Costil, S.; Lamraoui, A.; Langlade, C.; Heintz, O.; Oltra, R.

2014-01-01

Laser cleaning technology provides a safe, environmentally friendly and very cost effective way to improve cleaning and surface preparation of metallic materials. Compared with efficient cleaning processes, it can avoid the disadvantages of ductile materials prepared by conventional technologies (cracks induced by sand-blasting for example) and treat only some selected areas (due to the optical fibers). By this way, laser technology could have several advantages and expand the range of thermal spraying. Moreover, new generations of lasers (fiber laser, disc laser) allow the development of new methods. Besides a significant bulk reduction, no maintenance, low operating cost, laser fibers can introduce alternative treatments. Combining a short-pulse laser with a scanner allows new applications in terms of surface preparation. By multiplying impacts using scanning laser, it is possible to shape the substrate surface to improve the coating adhesion as well as the mechanical behaviour. In addition, during the interactions of the laser beam with metallic surfaces, several modifications can be induced and particularly thermal effects. Indeed, under ambient conditions, a limited oxidation of the clean surface can occur. This phenomenon has been investigated in detail for silicon but few works have been reported concerning metallic materials. This paper aims at studying the surface modifications induced on aluminium alloy substrates after laser texturing. After morphological observations (SEM), a deeper surface analysis will be performed using XPS (X-ray photoelectron spectroscopy) measures and microhardness testing.

On the morphological instability of a bubble during inertia-controlled growth

NASA Astrophysics Data System (ADS)

Martyushev, L. M.; Birzina, A. I.; Soboleva, A. S.

2018-06-01

The morphological stability of a spherical bubble growing under inertia control is analyzed. Based on the comparison of entropy productions for a distorted and undistorted surface and using the maximum entropy production principle, the morphological instability of the bubble under arbitrary amplitude distortions is shown. This result allows explaining a number of experiments where the surface roughness of bubbles was observed during their explosive-type growth.

Morphology Formation in PC/ABS Blends during Thermal Processing and the Effect of the Viscosity Ratio of Blend Partners

PubMed Central

Bärwinkel, Stefanie; Seidel, Andreas; Hobeika, Sven; Hufen, Ralf; Mörl, Michaela; Altstädt, Volker

2016-01-01

Morphology formation during compounding, as well as injection molding of blends containing 60 wt % polycarbonate (PC) and 40 wt % polybutadiene rubber-modified styrene-acrylonitrile copolymers (ABS), has been investigated by transmission electron microscopy (TEM). Profiles of the blend morphology have been recorded in injection-molded specimens and significant morphology gradients observed between their skin and core. A <10 µm thick surface layer with strongly dispersed and elongated nano-scale (streak-like) styrene acrylonitrile (SAN) phases and well-dispersed, isolated SAN-grafted polybutadiene rubber particles is followed by a 50–150 µm thick skin layer in which polymer morphology is characterized by lamellar SAN/ABS phases. Thickness of these lamellae increases with the distance from the specimen’s surface. In the core of the specimens the SAN-grafted polybutadiene rubber particles are exclusively present within the SAN phases, which exhibit a much coarser and less oriented, dispersed morphology compared to the skin. The effects of the viscosity of the SAN in the PC/ABS blends on phase morphologies and correlations with fracture mechanics in tensile and impact tests were investigated, including scanning electron microscopy (SEM) assessment of the fracture surfaces. A model explaining the mechanisms of morphology formation during injection molding of PC/ABS blends is discussed. PMID:28773780

Various fates of neuronal progenitor cells observed on several different chemical functional groups

NASA Astrophysics Data System (ADS)

Liu, Xi; Wang, Ying; He, Jin; Wang, Xiu-Mei; Cui, Fu-Zhai; Xu, Quan-Yuan

2011-12-01

Neuronal progenitor cells cultured on gold-coated glass surfaces modified by different chemical functional groups, including hydroxyl (-OH), carboxyl (-COOH), amino (-NH2), bromo (-Br), mercapto (-SH), - Phenyl and methyl (-CH3), were studied here to investigate the influence of surface chemistry on the cells' adhesion, morphology, proliferation and functional gene expression. Focal adhesion staining indicated in the initial culture stage cells exhibited morphological changes in response to different chemical functional groups. Cells cultured on -NH2 grafted surface displayed focal adhesion plaque and flattened morphology and had the largest contact area. However, their counter parts on -CH3 grafted surface displayed no focal adhesion and rounded morphology and had the smallest contact area. After 6 days culture, the proliferation trend was as follows: -NH2 > -SH> -COOH> - Phenyl > - Br > -OH> -CH3. To determine the neural functional properties of the cells affected by surface chemistry, the expression of glutamate decarboxylase (GAD67), nerve growth factor (NGF) and brainderived neurotrophic factor (BDNF) were characterized. An increase of GAD67 expression was observed on -NH2, -COOH and -SH grafted surfaces, while no increase in NGF and BDNF expression was observed on any chemical surfaces. These results highlight the importance of surface chemistry in the fate determination of neuronal progenitor cells, and suggest that surface chemistry must be considered in the design of biomaterials for neural tissue engineering.

Theory of multiple quantum dot formation in strained-layer heteroepitaxy

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

Du, Lin; Maroudas, Dimitrios, E-mail: maroudas@ecs.umass.edu

2016-07-11

We develop a theory for the experimentally observed formation of multiple quantum dots (QDs) in strained-layer heteroepitaxy based on surface morphological stability analysis of a coherently strained epitaxial thin film on a crystalline substrate. Using a fully nonlinear model of surface morphological evolution that accounts for a wetting potential contribution to the epitaxial film's free energy as well as surface diffusional anisotropy, we demonstrate the formation of multiple QD patterns in self-consistent dynamical simulations of the evolution of the epitaxial film surface perturbed from its planar state. The simulation predictions are supported by weakly nonlinear analysis of the epitaxial filmmore » surface morphological stability. We find that, in addition to the Stranski-Krastanow instability, long-wavelength perturbations from the planar film surface morphology can trigger a nonlinear instability, resulting in the splitting of a single QD into multiple QDs of smaller sizes, and predict the critical wavelength of the film surface perturbation for the onset of the nonlinear tip-splitting instability. The theory provides a fundamental interpretation for the observations of “QD pairs” or “double QDs” and other multiple QDs reported in experimental studies of epitaxial growth of semiconductor strained layers and sets the stage for precise engineering of tunable-size nanoscale surface features in strained-layer heteroepitaxy by exploiting film surface nonlinear, pattern forming phenomena.« less

Morphological study of polymethyl methacrylate microcapsules filled with self-healing agents

NASA Astrophysics Data System (ADS)

Ahangaran, Fatemeh; Hayaty, Mehran; Navarchian, Amir H.

2017-03-01

Polymethyl methacrylate (PMMA) microcapsules filled with epoxy prepolymer, 3-aminomethyl-3,5,5-trimethylcyclohexylamine, and pentaerythritol tetrakis (3-mercaptopropionate) as healing agents have been prepared separately through internal phase separation method for self-healing purposes. PMMA with two different molecular weights (M bar1 = 36,000 g/mol and M bar2 = 550,000 g/mol) were used with two types of different emulsifiers (ionic and polymeric) to prepare microcapsules. The morphology of healing agent microcapsules was investigated using field emission scanning electron microscopy (FESEM). It was found that PMMA microcapsules separately filled with epoxy and amine had core-shell morphologies with smooth surfaces. The mercaptan/PMMA particles exhibited core-shell and acorn-shape morphologies. The surface morphology of mercaptan microcapsules changed from holed to plain in different emulsion systems. The spreading coefficient (S) of phases in the prepared emulsion systems were calculated from interfacial tension (σ) and contact angle (θ) measurements. The theoretical equilibrium morphology of PMMA microcapsules was predicted according to spreading coefficient values of phases in emulsion systems. It was also found that the surface morphology of PMMA microcapsules depended strongly on the nature of the core, molecular weight of PMMA, type and concentration of emulsifier.

Description, dissection, and subsampling of Apollo 14 core sample 14230

NASA Technical Reports Server (NTRS)

Fryxell, R.; Heiken, G.

1971-01-01

Core sample 14230, collected at Triplet Crater near the Fra Mauro landing site of the Apollo 14 mission, was dissected in greater detail than any previous core. Sediment from the actual lunar surface was missing, and 6.7 grams of sediment were removed from the base of the core for a portion of the biotest prime sample. Upper and lower portions of the original 70.7-gram core (12.5 centimeters long) were fractured excessively but not mixed stratigraphically. Three major morphologic units and 11 subdivisions were recognized. Dissection provided 55 subsamples in addition to three others made by removing longitudinal sections of the core impregnated with n-butyl methacrylate for use as a permanent documentary record and for studies requiring particles of known orientation.

Solidification under zero gravity: A Long Duration Exposure Facility (LDEF) experiment for an early space shuttle mission. [project planning

NASA Technical Reports Server (NTRS)

Bailey, J. A.

1976-01-01

Project planning for two series of simple experiments on the effect of zero gravity on the melting and freezing of metals and nonmetals is described. The experiments will be performed in the Long Duration Exposure Facility, and their purpose will be to study: (1) the general morphology of metals and nonmetals during solidification, (2) the location of ullage space (liquid-vapor interfaces), and (3) the magnitude of surface tension driven convection during solidification of metals and nonmetals. The preliminary design of the experiments is presented. Details of the investigative approach, experimental procedure, experimental hardware, data reduction and analysis, and anticipated results are given. In addition a work plan and cost analysis are provided.

Effect of polymer type on characterization and filtration performances of multi-walled carbon nanotubes (MWCNT)-COOH-based polymeric mixed matrix membranes.

PubMed

Sengur-Tasdemir, Reyhan; Mokkapati, Venkata R S S; Koseoglu-Imer, Derya Y; Koyuncu, Ismail

2018-05-01

Multi-walled carbon nanotubes (MWCNTs) can be used for the fabrication of mixed matrix polymeric membranes that can enhance filtration perfomances of the membranes by modifying membrane surface properties. In this study, detailed characterization and filtration performances of MWCNTs functionalized with COOH group, blended into polymeric flat-sheet membranes were investigated using different polymer types. Morphological characterization was carried out using atomic force microscopy, scanning electron microscopy and contact angle measurements. For filtration performance tests, protein, dextran, E. coli suspension, Xanthan Gum and real activated sludge solutions were used. Experimental data and analyses revealed that Polyethersulfone (PES) + MWCNT-COOH mixed matrix membranes have superior performance abilities compared to other tested membranes.

Carbon nanowall scaffold to control culturing of cervical cancer cells

NASA Astrophysics Data System (ADS)

Watanabe, Hitoshi; Kondo, Hiroki; Okamoto, Yukihiro; Hiramatsu, Mineo; Sekine, Makoto; Baba, Yoshinobu; Hori, Masaru

2014-12-01

The effect of carbon nanowalls (CNWs) on the culturing rate and morphological control of cervical cancer cells (HeLa cells) was investigated. CNWs with different densities were grown using plasma-enhanced chemical vapor deposition and subjected to post-growth plasma treatment for modification of the surface terminations. Although the surface wettability of the CNWs was not significantly dependent on the CNW densities, the cell culturing rates were significantly dependent. Morphological changes of the cells were not significantly dependent on the density of CNWs. These results indicate that plasma-induced surface morphology and chemical terminations enable nanobio applications using carbon nanomaterials.

Data on the surface morphology of additively manufactured Ti-6Al-4V implants during processing by plasma electrolytic oxidation.

PubMed

van Hengel, Ingmar A J; Riool, Martijn; Fratila-Apachitei, Lidy E; Witte-Bouma, Janneke; Farrell, Eric; Zadpoor, Amir A; Zaat, Sebastian A J; Apachitei, Iulian

2017-08-01

Additively manufactured Ti-6Al-4V implants were biofunctionalized using plasma electrolytic oxidation. At various time points during this process scanning electron microscopy imaging was performed to analyze the surface morphology (van Hengel et al., 2017) [1]. This data shows the changes in surface morphology during plasma electrolytic oxidation. Data presented in this article are related to the research article "Selective laser melting porous metallic implants with immobilized silver nanoparticles kill and prevent biofilm formation by methicillin-resistant Staphylococcus aureus" (van Hengel et al., 2017) [1].

Effects of annealing temperature and duration on the morphological and optical evolution of self-assembled Pt nanostructures on c-plane sapphire.

PubMed

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

2017-01-01

Metallic nanostructures (NSs) have been widely adapted in various applications and their physical, chemical, optical and catalytic properties are strongly dependent on their surface morphologies. In this work, the morphological and optical evolution of self-assembled Pt nanostructures on c-plane sapphire (0001) is demonstrated by the control of annealing temperature and dwelling duration with the distinct thickness of Pt films. The formation of Pt NSs is led by the surface diffusion, agglomeration and surface and interface energy minimization of Pt thin films, which relies on the growth parameters such as system temperature, film thickness and annealing duration. The Pt layer of 10 nm shows the formation of overlaying NPs below 650°C and isolated Pt nanoparticles above 700°C based on the enhanced surface diffusion and Volmer-Weber growth model whereas larger wiggly nanostructures are formed with 20 nm thick Pt layers based on the coalescence growth model. The morphologies of Pt nanostructures demonstrate a sharp distinction depending on the growth parameters applied. By the control of dwelling duration, the gradual transition from dense Pt nanoparticles to networks-like and large clusters is observed as correlated to the Rayleigh instability and Ostwald ripening. The various Pt NSs show a significant distinction in the reflectance spectra depending on the morphology evolution: i.e. the enhancement in UV-visible and NIR regions and the related optical properties are discussed in conjunction with the Pt NSs morphology and the surface coverage.

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.

River network and watershed morphology analysis with potential implications towards basin classification

NASA Astrophysics Data System (ADS)

Bugaets, Andrey; Gartsman, Boris; Bugaets, Nadezhda

2013-04-01

Generally, the investigation of river network composition and watersheds morphology (fluvial geomorphology), constituting one of the key patterns of land surface, is a fundamental question of Earth Sciences. Recent ideas in this research field are the equilibrium and optimal, in the sense of minimum energy expenditure, river network evolution under constant or slowly varying conditions (Rodriguez-Iturbe, Rinaldo, 1997). It follows to such network behavior as self-similarity, self-affinity and self-organization. That is to say, under relatively stable conditions the river systems tend to some "good composed" form and vice-versa. Lately appearing global free available detailed DEM covers involve new possibilities in this research field. We develop new methodology and program package for river network structure and watershed morphology detailed analysis on the base of ArcMap tools. Different characteristics of river network (e.g. ordering, coefficients of Horton's laws, Shannon entropy, fractal dimension) and basin morphology (e.g. diagrams of average elevation, slope, width and energy index against distance to outlet along streams) could be calculated to find a good indicators of intensity and non-equilibrium of watershed evolution. Watersheds are non-conservative systems in which energy is dissipated by transporting water and sediment in geomorphic adjustment of the slopes and channels. The problem of estimating the amount of energy expenditure associated with overcoming surface and system resistance is extremely complicated to solve. A simplification on a river network scale is to consider energy expenditure to be primarily associated with friction of the fluid. We propose a new technique to analyze the catchment landforms based on so-called "energy function" that is a distribution of total energy index against distance from outlet. As potential energy of water on the hillslopes is transformed into kinetic energy of the flowing fluid-sediment mixture in the runoff process, the energy is dissipated from the system. The rate of energy dissipation is defined as the work that a fluid element needs to perform to overcome friction at the unit area. Appling the product of local slope and watershed area, i.e. calculating the total energy index at the different distance from outlet, one gets the watershed "energy function" E(x). Application results indicate that the proposed method could be used for watersheds classification, regionalization and paleoreconstructions. NASA-SRTM DEM of 3" resolution has been employed to analyze the 24 watersheds within Amur River Basin with area 20-70 thousand km2 (7-8 order). The study was carried out, in particular, to assess the limitation of SRTM DEM data, especially in flat terrains. The study also revealed that some of regularities investigated are described satisfactorily by well-known simplest model of drainage networks, so-called Peano's basin.

Morphological observation and characterization of the Pseudoregma bambucicola with the scanning electron microscope.

PubMed

Nong, Xiang; Zeng, Xuemei; Yang, Yaojun; Liang, Zi; Tang, Mei; Liao, Lejuan; Luo, Chaobing

2017-11-01

Both leica microscopic camera system and scanning electron microscopy was used to observe and characterize the feet, back, abdomen, antennae and mouthparts of the Pseudoregma bambucicola from the bamboo, Bambusa multiplex . The possible functions of all the external morphological characteristics of the P. bambucicola were described and discussed in detail, which offers a basis for further enriching the biology, phylogeny and ecological niche of the P. bambucicola . Moreover, the morphological results should contribute to morphological identification and differentiation of the P. bambucicola from other aphids in the same family.

Geologic map of Mars

USGS Publications Warehouse

Tanaka, Kenneth L.; Skinner, James A.; Dohm, James M.; Irwin, Rossman P.; Kolb, Eric J.; Fortezzo, Corey M.; Platz, Thomas; Michael, Gregory G.; Hare, Trent M.

2014-01-01

This global geologic map of Mars, which records the distribution of geologic units and landforms on the planet's surface through time, is based on unprecedented variety, quality, and quantity of remotely sensed data acquired since the Viking Orbiters. These data have provided morphologic, topographic, spectral, thermophysical, radar sounding, and other observations for integration, analysis, and interpretation in support of geologic mapping. In particular, the precise topographic mapping now available has enabled consistent morphologic portrayal of the surface for global mapping (whereas previously used visual-range image bases were less effective, because they combined morphologic and albedo information and, locally, atmospheric haze). Also, thermal infrared image bases used for this map tended to be less affected by atmospheric haze and thus are reliable for analysis of surface morphology and texture at even higher resolution than the topographic products.

Altered Calcium Dynamics in Cardiac Cells Grown on Silane-Modified Surfaces

PubMed Central

Ravenscroft-Chang, Melissa S.; Stohlman, Jayna; Molnar, Peter; Natarajan, Anupama; Canavan, Heather E.; Teliska, Maggie; Stancescu, Maria; Krauthamer, Victor; Hickman, J.J.

2013-01-01

Chemically defined surfaces were created using self-assembled monolayers (SAMs) of hydrophobic and hydrophilic silanes as models for implant coatings, and the morphology and physiology of cardiac myocytes plated on these surfaces were studied in vitro. We focused on changes in intracellular Ca2+ because of its essential role in regulating heart cell function. The SAM-modified coverslips were analyzed using X-ray Photoelectron Spectroscopy to verify composition. The morphology and physiology of the cardiac cells were examined using fluorescence microscopy and intracellular Ca2+ imaging. The imaging experiments used the fluorescent ratiometric dye fura-2, AM to establish both the resting Ca2+ concentration and the dynamic responses to electrical stimulation. A significant difference in excitation-induced Ca2+ changes on the different silanated surfaces was observed. However, no significant change was noted based on the morphological analysis. This result implies a difference in internal Ca2+ dynamics, and thus cardiac function, occurs when the composition of the surface is different, and this effect is independent of cellular morphology. This finding has implications for histological examination of tissues surrounding implants, the choice of materials that could be beneficial as implant coatings and understanding of cell-surface interactions in cardiac systems. PMID:19828193

Effects of erbium, chromium:YSGG laser irradiation on root surface: morphological and atomic analytical studies.

PubMed

Kimura, Y; Yu, D G; Kinoshita, J; Hossain, M; Yokoyama, K; Murakami, Y; Nomura, K; Takamura, R; Matsumoto, K

2001-04-01

The purpose of this study was to investigate the morphological and atomic changes on the root surface by stereoscopy, field emission-scanning electron microscopy (FE-SEM), and energy dispersive X-ray spectroscopy (SEM-EDX) after erbium, chromium:yttrium, scandium, gallium, garnet (Er,Cr:YSGG) laser irradiation in vitro. There have been few reports on morphological and atomic analytical study on root surface by Er,Cr:YSGG laser irradiation. Eighteen extracted human premolar and molar teeth were irradiated on root surfaces at a vertical position with water-air spray by an Er,Cr:YSGG laser at the parameter of 5.0 W and 20 Hz for 5 sec while moving. The samples were then morphologically observed by stereoscopy and FE-SEM and examined atomic-analytically by SEM-EDX. Craters having rough but clean surfaces and no melting or carbonization were observed in the samples. An atomic analytical examination showed that the calcium ratio to phosphorus showed no significant changes between the control and irradiated areas (p > 0.01). These results showed that the Er,Cr:YSGG laser has a good cutting effect on root surface and causes no burning or melting after laser irradiation.

Controllable morphology of flux avalanches in microstructured superconductors

NASA Astrophysics Data System (ADS)

Motta, M.; Colauto, F.; Vestgârden, J. I.; Fritzsche, J.; Timmermans, M.; Cuppens, J.; Attanasio, C.; Cirillo, C.; Moshchalkov, V. V.; Van de Vondel, J.; Johansen, T. H.; Ortiz, W. A.; Silhanek, A. V.

2014-04-01

The morphology of abrupt bursts of magnetic flux into superconducting films with engineered periodic pinning centers (antidots) has been investigated. Guided flux avalanches of thermomagnetic origin develop a treelike structure, with the main trunk perpendicular to the borders of the sample, while secondary branches follow well-defined directions determined by the geometrical details of the underlying periodic pinning landscape. Strikingly, we demonstrate that in a superconductor with relatively weak random pinning the morphology of such flux avalanches can be fully controlled by proper combinations of lattice symmetry and antidot geometry. Moreover, the resulting flux patterns can be reproduced, to the finest details, by simulations based on a phenomenological thermomagnetic model. In turn, this model can be used to predict such complex structures and to estimate physical variables of more difficult experimental access, such as the local values of temperature and electric field.

Virtual mission stage I: Implications of a spaceborne surface water mission

NASA Astrophysics Data System (ADS)

Clark, E. A.; Alsdorf, D. E.; Bates, P.; Wilson, M. D.; Lettenmaier, D. P.

2004-12-01

The interannual and interseasonal variability of the land surface water cycle depend on the distribution of surface water in lakes, wetlands, reservoirs, and river systems; however, measurements of hydrologic variables are sparsely distributed, even in industrialized nations. Moreover, the spatial extent and storage variations of lakes, reservoirs, and wetlands are poorly known. We are developing a virtual mission to demonstrate the feasibility of observing surface water extent and variations from a spaceborne platform. In the first stage of the virtual mission, on which we report here, surface water area and fluxes are emulated using simulation modeling over three continental scale river basins, including the Ohio River, the Amazon River and an Arctic river. The Variable Infiltration Capacity (VIC) macroscale hydrologic model is used to simulate evapotranspiration, soil moisture, snow accumulation and ablation, and runoff and streamflow over each basin at one-eighth degree resolution. The runoff from this model is routed using a linear transfer model to provide input to a much more detailed flow hydraulics model. The flow hydraulics model then routes runoff through various channel and floodplain morphologies at a 250 m spatial and 20 second temporal resolution over a 100 km by 500 km domain. This information is used to evaluate trade-offs between spatial and temporal resolutions of a hypothetical high resolution spaceborne altimeter by synthetically sampling the resultant model-predicted water surface elevations.

The Influence of Roof Material on Diurnal Urban Canyon Breathing

NASA Astrophysics Data System (ADS)

Abuhegazy, Mohamed; Yaghoobian, Neda

2017-11-01

Improvements in building energy use, air quality in urban canyons and in general urban microclimates require understanding the complex interaction between urban morphology, materials, climate, and inflow conditions. Review of the literature indicates that despite a long history of valuable urban microclimate studies, more comprehensive approaches are needed to address energy, and heat and flow transport in urban areas. In this study, a more comprehensive simulation of the diurnally varying street canyon flow and associated heat transport is numerically investigated, using Large-eddy Simulation (LES). We use computational modeling to examine the impact of diurnal variation of the heat fluxes from urban surfaces on the air flow and temperature distribution in street canyons with a focus on the role of roof materials and their temperature footprints. A detailed building energy model with a three-dimensional raster-type geometry provides urban surface heat fluxes as thermal boundary conditions for the LES to determine the key aero-thermodynamic factors that affect urban street ventilation.

Current characterization methods for cellulose nanomaterials.

PubMed

Foster, E Johan; Moon, Robert J; Agarwal, Umesh P; Bortner, Michael J; Bras, Julien; Camarero-Espinosa, Sandra; Chan, Kathleen J; Clift, Martin J D; Cranston, Emily D; Eichhorn, Stephen J; Fox, Douglas M; Hamad, Wadood Y; Heux, Laurent; Jean, Bruno; Korey, Matthew; Nieh, World; Ong, Kimberly J; Reid, Michael S; Renneckar, Scott; Roberts, Rose; Shatkin, Jo Anne; Simonsen, John; Stinson-Bagby, Kelly; Wanasekara, Nandula; Youngblood, Jeff

2018-04-23

A new family of materials comprised of cellulose, cellulose nanomaterials (CNMs), having properties and functionalities distinct from molecular cellulose and wood pulp, is being developed for applications that were once thought impossible for cellulosic materials. Commercialization, paralleled by research in this field, is fueled by the unique combination of characteristics, such as high on-axis stiffness, sustainability, scalability, and mechanical reinforcement of a wide variety of materials, leading to their utility across a broad spectrum of high-performance material applications. However, with this exponential growth in interest/activity, the development of measurement protocols necessary for consistent, reliable and accurate materials characterization has been outpaced. These protocols, developed in the broader research community, are critical for the advancement in understanding, process optimization, and utilization of CNMs in materials development. This review establishes detailed best practices, methods and techniques for characterizing CNM particle morphology, surface chemistry, surface charge, purity, crystallinity, rheological properties, mechanical properties, and toxicity for two distinct forms of CNMs: cellulose nanocrystals and cellulose nanofibrils.

The formation of periodic micro/nano structured on stainless steel by femtosecond laser irradiation

NASA Astrophysics Data System (ADS)

Yao, Caizhen; Gao, Wei; Ye, Yayun; Jiang, Yong; Xu, Shizhen; Yuan, Xiaodong

2017-07-01

Stainless steel surface was irradiated by linear polarized laser (800 nm, 35 fs, 4 Hz and 0.7 J/cm2) with different pulse numbers. Environmental scanning electron microscope (ESEM/EDS) was used for detailed morphology, microstructure and composition studies. The wettability of irradiated steel surface was tested by Interface Tensiometer JC-2000X and compared with untreated stainless steel. Results showed that micro/nanostripes with different periods were formed. The period increased with the increasing pulse numbers from 450 nm for 90 pulses to 500 nm for 180 pulses. The orientation of those stripes was parallel with the laser beam polarization. Nanoparticles were observed on those periodic structures. EDS indicated that the atomic ratio of Cr increased and the atomic ratios of Fe and Ni decreased after laser irradiation, which may enhance the corrosion resistance due to the Cr-rich layer. The prepared structure exhibited hydrophobic property without further treatment. The formation mechanism of micro/nanoperiodic structures was also explored.

Elevated gamma-rays shielding property in lead-free bismuth tungstate by nanofabricating structures

NASA Astrophysics Data System (ADS)

Liu, Jun-Hua; Zhang, Quan-Ping; Sun, Nan; Zhao, Yang; Shi, Rui; Zhou, Yuan-Lin; Zheng, Jian

2018-01-01

Radiation shielding materials have attracted much attention across academia and industry because of the increasing of nuclear activities. To achieve the materials with low toxicity but good protective capability is one of the most significant goals for personal protective articles. Here, bismuth tungstate nanostructures are controllably fabricated by a versatile hydrothermal treatment under various temperatures. The crystals structure and morphology of products are detailedly characterized with X-ray diffraction, electron microscope and specific surface area. It is noteworthy that desired Bi2WO6 nanosheets treated with 190 °C show the higher specific surface area (19.5 m2g-1) than that of the other two products. Importantly, it has a close attenuating property to lead based counterpart for low energy gamma-rays. Due to the less toxicity, Bi2WO6 nanosheets are more suitable than lead based materials to fabricate personal protective articles for shielding low energy radiations and have great application prospect as well as market potential.

[Observation by transmission electron microscope and identification of endophytic bacteria isolated from Bursaphelenchus xylophilus and B. mucronatus].

PubMed

Yuan, Weimin; Wu, Xiaoqin; Ye, Jianren; Tian, Xiaojing

2011-08-01

The pine wood nematode, Bursaphlenchus xylophilus, morphologically similar to B. mucronatus, is the pathogen of pine wilt disease. This study was focused on the endophytic bacteria present in these nematodes. Detailed observations were made on sections of all parts of the two types of nematodes by transmission electron microscope. The nematodes were surface-sterilized by soaking in 1% mercuric chloride and antibiotic mixture, and then ground and cultured on nutrient agar plate. The physiological and biochemical characteristics combined with molecular characterization of bacteria were analyzed and identified. Endophytic bacteria were found in intestines of the two nematodes by transmission electron microscope observations. On the basis of surface sterilization, total three bacteria strains were obtained from B. xylophilus and B. mucronatus. These bacteria belong to Stenotrophomonas and Ewingella. It confirms the presence of endophytic bacteria in Bursaphelenchus xylophilus and B. mucronatus and these bacteria may play a physical and ecological roles in nematodes.

Image processing of metal surface with structured light

NASA Astrophysics Data System (ADS)

Luo, Cong; Feng, Chang; Wang, Congzheng

2014-09-01

In structured light vision measurement system, the ideal image of structured light strip, in addition to black background , contains only the gray information of the position of the stripe. However, the actual image contains image noise, complex background and so on, which does not belong to the stripe, and it will cause interference to useful information. To extract the stripe center of mental surface accurately, a new processing method was presented. Through adaptive median filtering, the noise can be preliminary removed, and the noise which introduced by CCD camera and measured environment can be further removed with difference image method. To highlight fine details and enhance the blurred regions between the stripe and noise, the sharping algorithm is used which combine the best features of Laplacian operator and Sobel operator. Morphological opening operation and closing operation are used to compensate the loss of information.Experimental results show that this method is effective in the image processing, not only to restrain the information but also heighten contrast. It is beneficial for the following processing.

Mercury. [Mariner 10 observations and planetary properties

NASA Technical Reports Server (NTRS)

Gault, D. E.; Cassen, P.; Burns, J. A.; Strom, R. G.

1977-01-01

Information about Mercury obtained with the Mariner 10 spacecraft is summarized together with results of theoretical studies and ground-based observations. It is shown that Mercury is very likely a differentiated body, probably contains a large earthlike iron-rich core, and displays a surface similar to the moon's, which suggests a similar evolutionary history. The size and mass of Mercury are discussed along with its orbit, rotation, atmosphere, magnetic field, and magnetosphere. Surface features of Mercury are described on the basis of Mariner 10 pictures, with detailed attention given to the major physiographic provinces, the structure of the Caloris basin, the tectonic framework of the planet, crater morphology, the planet's optical and thermal properties, and cartography. The composition and structure of the interior are examined, and the thermal history of Mercury is considered. The planet's geologic history is divided into five stages or epochs: (1) accretion and differentiation, (2) terminal heavy bombardment, (3) Caloris basin formation, (4) basin flooding, and (5) postfilling lighter bombardment.

Cryo-electron tomography investigation of serum albumin-camouflaged tobacco mosaic virus nanoparticles.

PubMed

Gulati, Neetu M; Pitek, Andrzej S; Steinmetz, Nicole F; Stewart, Phoebe L

2017-03-09

Nanoparticles offer great potential in drug delivery and imaging, but shielding strategies are necessary to increase circulation time and performance. Structure-function studies are required to define the design rules to achieve effective shielding. With several formulations reaching clinical testing and approval, the ability to assess and detail nanoparticle formulations at the single particle level is becoming increasingly important. To address this need, we use cryo-electron tomography (cryo-ET) to investigate stealth-coated nanoparticles. As a model system, we studied the soft matter nanotubes formed by tobacco mosaic virus (TMV) coated with human serum albumin (SA) stealth proteins. Cryo-ET and subtomogram averaging allow for visualization of individual SA molecules and determination of their orientations relative to the TMV surface, and also for measurement of the surface coverage provided by added stealth proteins. This information fills a critical gap in the understanding of the structural morphology of stealth-coated nanoparticles, and therefore cryo-ET may play an important role in guiding the development of future nanoparticle-based therapeutics.

Effect of cathode vibration and heat treatment on electromagnetic properties of flake-shaped diatomite coated with Ni-Fe alloy by electroplating

NASA Astrophysics Data System (ADS)

Lan, Mingming; Li, Huiqin; Huang, Weihua; Xu, Guangyin; Li, Yan

2015-03-01

In this paper, flake-shaped diatomite particles were used as forming templates for the fabrication of the ferromagnetic functional fillers by way of electroplating Ni-Fe alloy method. The effects of cathode vibration frequency on the content of Ni-Fe alloy in the coating and the surface morphologies of the coatings were evaluated. The electromagnetic properties of the coated diatomite particles before and after heat treatment were also investigated in detail. The results show that the core-shell flake-shaped diatomite particles with high content of Ni-Fe alloy and good surface qualities of the coatings can be obtained by adjusting cathode vibration frequency. The coated diatomite particles with heat treatment filled paraffin wax composites exhibit a superior microwave absorbing and electromagnetic properties compared to the non-heat treated samples. Additionally, the peaks of reflection loss are found to be able to shift to lower frequency by the heat treatment process, which indicates the heat treatment can adjust microwave absorbing frequency band.

Fine structures of embryonic discs of in vivo post-hatching porcine blastocysts at the pre-primitive streak stage.

PubMed

Xia, P; Liu, Z; Qin, P

2011-04-01

To date, reports about the ultrastructure of porcine embryonic discs have not shown details of the primitive streak. The main objective of this study was to examine the ultrastructure of interior and exterior embryonic discs in porcine in vivo blastocysts with diameters of 1, 3 and 9 mm using scanning electron microscopy and transmission electron microscopy. For the first time, we revealed the ultrastructure of the unusual group of cells in the pre-primitive streak area of embryonic discs. The cells were 1-2 μm in diameter, had high electron density and contained abundant, free ribosomes and endoplasmic reticulum. These primitive streak cells could represent original embryonic stem cells or represent a stem cell niche. The results also showed three types of cells on the exterior surface of the embryonic discs. Moreover, our results provided morphological evidence of condensed nuclei in the smooth cells on the surface of the embryonic disc. © 2010 Blackwell Verlag GmbH.

Highly selective and efficient imprinted polymers based on carboxyl-functionalized magnetic nanoparticles for the extraction of gallic acid from pomegranate rind.

PubMed

Zhang, Junjie; Li, Benqiang; Yue, Huijuan; Wang, Jing; Zheng, Yuansuo

2018-01-01

With the combined surface imprinting technique and immobilized template strategy, molecularly imprinted magnetic nanoparticles were successfully prepared and coupled with high-performance liquid chromatography to selectively separate and determine gallic acid from the pomegranate rind. On the surface of carboxyl-functionalized magnetic nanospheres, thin imprinting shells were formed using dopamine as monomer and crosslinker. The characteristics, polymerization conditions, and adsorption performances of the resultant nanomaterials were investigated in detail. In addition of good crystallinity, satisfactory magnetism, and uniform morphology of the obtained polymers, they had rapid binding kinetics, high adsorption capacity, and favorable reusability. In the mixed solution of four hydroxybenzoic acids, the prepared nanomaterials have an excellent selectivity to gallic acid with an imprinting factor of as high as 17.5. Therefore, the polymers have great potentials in specific extraction and enrichment of gallic acid from the complex natural resources. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Evolving application of biomimetic nanostructured hydroxyapatite

PubMed Central

Roveri, Norberto; Iafisco, Michele

2010-01-01

By mimicking Nature, we can design and synthesize inorganic smart materials that are reactive to biological tissues. These smart materials can be utilized to design innovative third-generation biomaterials, which are able to not only optimize their interaction with biological tissues and environment, but also mimic biogenic materials in their functionalities. The biomedical applications involve increasing the biomimetic levels from chemical composition, structural organization, morphology, mechanical behavior, nanostructure, and bulk and surface chemical–physical properties until the surface becomes bioreactive and stimulates cellular materials. The chemical–physical characteristics of biogenic hydroxyapatites from bone and tooth have been described, in order to point out the elective sides, which are important to reproduce the design of a new biomimetic synthetic hydroxyapatite. This review outlines the evolving applications of biomimetic synthetic calcium phosphates, details the main characteristics of bone and tooth, where the calcium phosphates are present, and discusses the chemical–physical characteristics of biomimetic calcium phosphates, methods of synthesizing them, and some of their biomedical applications. PMID:24198477

Fracture mechanics and surface chemistry investigations of environment-assisted crack growth

NASA Technical Reports Server (NTRS)

Wei, R. P.; Klier, K.; Simmons, G. W.; Chou, Y. T.

1984-01-01

It is pointed out that environment-assisted subcritical crack growth in high-strength steels and other high-strength alloys (particularly in hydrogen and in hydrogenous environments) is an important technological problem of long standing. This problem is directly related to issues of structural integrity, durability, and reliability. The terms 'hydrogen embrittlement' and 'stress corrosion cracking' have been employed to describe the considered phenomenon. This paper provides a summary of contributions made during the past ten years toward the understanding of environmentally assisted crack growth. The processes involved in crack growth are examined, and details regarding crack growth and chemical reactions are discussed, taking into account crack growth in steels exposed to water/water vapor, the effect of hydrogen, reactions involving hydrogen sulfide, and aspects of fracture surface morphology and composition. Attention is also given to the modeling of crack growth response, crack growth in gas mixtures, and the interaction of solute atoms with the crack-tip stress field.

On the Distinction between Regular and Irregular Inflectional Morphology: Evidence from Dinka

ERIC Educational Resources Information Center

Ladd, D. Robert; Remijsen, Bert; Manyang, Caguor Adong

2009-01-01

Discussions of the psycholinguistic significance of regularity in inflectional morphology generally deal with languages in which regular forms can be clearly identified and revolve around whether there are distinct processing mechanisms for regular and irregular forms. We present a detailed description of Dinka's notoriously irregular noun number…

Aureobasidium pullulans morphology: two adapted polysaccharide stains.

PubMed

Oller, Anna R

2005-12-01

Morphological stages of Aureobasidium pullulans were investigated utilizing different media ingredients and were visualized by bright-field microscopy. A polysaccharide stain was developed to stain chlamydospores, cell walls, hyphae, and conidia, since current staining techniques do not reveal subcellular details to identify fungi, especially those that exhibit polysaccharide secretions.

Gender differences in knee morphology and the prospects for implant design in total knee replacement.

PubMed

Asseln, Malte; Hänisch, Christoph; Schick, Fabian; Radermacher, Klaus

2018-05-14

Morphological differences between female and male knees have been reported in the literature, which led to the development of so-called gender-specific implants. However, detailed morphological descriptions covering the entire joint are rare and little is known regarding whether gender differences are real sexual dimorphisms or can be explained by overall differences in size. We comprehensively analysed knee morphology using 33 features of the femur and 21 features of the tibia to quantify knee shape. The landmark recognition and feature extraction based on three-dimensional surface data were fully automatically applied to 412 pathological (248 female and 164 male) knees undergoing total knee arthroplasty. Subsequently, an exploratory statistical analysis was performed and linear correlation analysis was used to investigate normalization factors and gender-specific differences. Statistically significant differences between genders were observed. These were pronounced for distance measurements and negligible for angular (relative) measurements. Female knees were significantly narrower at the same depth compared to male knees. The correlation analysis showed that linear correlations were higher for distance measurements defined in the same direction. After normalizing the distance features according to overall dimensions in the direction of their definition, gender-specific differences disappeared or were smaller than the related confidence intervals. Implants should not be linearly scaled according to one dimension. Instead, features in medial/lateral and anterior/posterior directions should be normalized separately (non-isotropic scaling). However, large inter-individual variations of the features remain after normalization, suggesting that patient-specific design solutions are required for an improved implant design, regardless of gender. Copyright © 2018 Elsevier B.V. All rights reserved.

Giant Hα Nebula Surrounding the Starburst Merger NGC 6240

NASA Astrophysics Data System (ADS)

Yoshida, Michitoshi; Yagi, Masafumi; Ohyama, Youichi; Komiyama, Yutaka; Kashikawa, Nobunari; Tanaka, Hisashi; Okamura, Sadanori

2016-03-01

We revealed the detailed structure of a vastly extended Hα-emitting nebula (“Hα nebula”) surrounding the starburst/merging galaxy NGC 6240 by deep narrow-band imaging observations with the Subaru Suprime-Cam. The extent of the nebula is ˜90 kpc in diameter and the total Hα luminosity amounts to LHα ≈ 1.6 × 1042 erg s-1. The volume filling factor and the mass of the warm ionized gas are ˜10-4-10-5 and ˜5 × 108 M⊙, respectively. The nebula has a complicated structure, which includes numerous filaments, loops, bubbles, and knots. We found that there is a tight spatial correlation between the Hα nebula and the extended soft-X-ray-emitting gas, both in large and small scales. The overall morphology of the nebula is dominated by filamentary structures radially extending from the center of the galaxy. A large-scale bipolar bubble extends along the minor axis of the main stellar disk. The morphology strongly suggests that the nebula was formed by intense outflows—superwinds—driven by starbursts. We also found three bright knots embedded in a looped filament of ionized gas that show head-tail morphologies in both emission-line and continuum, suggesting close interactions between the outflows and star-forming regions. Based on the morphology and surface brightness distribution of the Hα nebula, we propose the scenario that three major episodes of starburst/superwind activities, which were initiated ˜102 Myr ago, formed the extended ionized gas nebula of NGC 6240. Based on data collected at the Subaru Telescope, which is operated by the National Astronomical Observatory of Japan.

Martian deltas: Morphology and distribution

NASA Technical Reports Server (NTRS)

Rice, J. W., Jr.; Scott, D. H.

1993-01-01

Recent detailed mapping has revealed numerous examples of Martian deltas. The location and morphology of these deltas are described. Factors that contribute to delta morphology are river regime, coastal processes, structural stability, and climate. The largest delta systems on Mars are located near the mouths of Maja, Maumee, Vedra, Ma'adim, Kasei, and Brazos Valles. There are also several smaller-scale deltas emplaced near channel mouths situated in Ismenius Lacus, Memnonia, and Arabia. Delta morphology was used to reconstruct type, quantity, and sediment load size transported by the debouching channel systems. Methods initially developed for terrestrial systems were used to gain information on the relationships between Martian delta morphology, river regime, and coastal processes.

Biodegradable poly (lactic acid)/Cellulose nanocrystals (CNCs) composite microcellular foam: Effect of nanofillers on foam cellular morphology, thermal and wettability behavior.

PubMed

Borkotoky, Shasanka Sekhar; Dhar, Prodyut; Katiyar, Vimal

2018-01-01

This article addresses the elegant and green approach for fabrication of bio-based poly (lactic acid) (PLA)/cellulose nanocrystal (CNCs) bionanocomposite foam (PLA/CNC) with cellular morphology and hydrophobic surface behavior. Highly porous (porosity >80%) structure is obtained with interconnected pores and the effect of CNCs in the cell density (N f ) and cell size of foams are thoroughly investigated by morphological analysis. The thermo-mechanical investigations are performed for the foam samples and almost ∼1.7 and ∼2.2 fold increase in storage modulus is observed for the compressive and tensile mode respectively. PLA/CNC based bionanocomposite foams displayed similar thermal stability as base PLA foam. Detailed investigations of decomposition behavior are studied by using hyphenated thermogravimetric analysis-fourier transmission infrared spectroscopy (TGA-FTIR) system. Almost ∼13% increment is observed in crystallinity at highest loading of CNCs compared to neat counterpart. To investigate the splitting and spreading phenomenon of the wettability of the samples, linear model is used to find the Young's contact angle and contact angle hysteresis (CAH). Besides, ∼6.1 folds reduction in the density of PLA and the nanocomposite foams compared to PLA carries much significance in specialized application areas where weight is an important concern. Copyright © 2017 Elsevier B.V. All rights reserved.

Fatal falls involving stairs: an anthropological analysis of skeletal trauma.

PubMed

Rowbotham, Samantha K; Blau, Soren; Hislop-Jambrich, Jacqueline; Francis, Victoria

2018-06-01

The skeletal blunt force trauma resulting from fatal falls involving stairs is complex. There are countless ways an individual may fall when stairs are involved, and thus a variety of ways the skeleton may fracture. Therefore anecdotally, it may be said that there is no specific skeletal trauma characteristic of this fall type. In order to scientifically investigate this anecdotal understanding, this study provides a detailed investigation of the skeletal fracture patterns and morphologies resulting from fatal falls involving stairs. Skeletal trauma was analyzed using the full-body postmortem computed tomography scans of 57 individuals who died from a fall involving stairs. Trauma was examined in the context of the variables that potentially influence how an individual falls (i.e. sex, age, body mass index, number of stairs involved, psychoactive drugs, pre-existing conditions, landing surface and manner of the fall) using logistic regression. Skeletal trauma primarily occurred in the axial skeleton. An analysis of fracture patterns showed the cranial base was less likely to fracture in younger individuals and the cervical vertebrae were more likely to fracture in falls that involved more than half a flight of stairs. A total of 56 fracture morphologies were identified. Of these, diastatic fractures were less likely to occur in older individuals. Findings indicate that there are skeletal fracture patterns and morphologies characteristic of a fatal fall involving stairs.

Change Detection via Selective Guided Contrasting Filters

NASA Astrophysics Data System (ADS)

Vizilter, Y. V.; Rubis, A. Y.; Zheltov, S. Y.

2017-05-01

Change detection scheme based on guided contrasting was previously proposed. Guided contrasting filter takes two images (test and sample) as input and forms the output as filtered version of test image. Such filter preserves the similar details and smooths the non-similar details of test image with respect to sample image. Due to this the difference between test image and its filtered version (difference map) could be a basis for robust change detection. Guided contrasting is performed in two steps: at the first step some smoothing operator (SO) is applied for elimination of test image details; at the second step all matched details are restored with local contrast proportional to the value of some local similarity coefficient (LSC). The guided contrasting filter was proposed based on local average smoothing as SO and local linear correlation as LSC. In this paper we propose and implement new set of selective guided contrasting filters based on different combinations of various SO and thresholded LSC. Linear average and Gaussian smoothing, nonlinear median filtering, morphological opening and closing are considered as SO. Local linear correlation coefficient, morphological correlation coefficient (MCC), mutual information, mean square MCC and geometrical correlation coefficients are applied as LSC. Thresholding of LSC allows operating with non-normalized LSC and enhancing the selective properties of guided contrasting filters: details are either totally recovered or not recovered at all after the smoothing. These different guided contrasting filters are tested as a part of previously proposed change detection pipeline, which contains following stages: guided contrasting filtering on image pyramid, calculation of difference map, binarization, extraction of change proposals and testing change proposals using local MCC. Experiments on real and simulated image bases demonstrate the applicability of all proposed selective guided contrasting filters. All implemented filters provide the robustness relative to weak geometrical discrepancy of compared images. Selective guided contrasting based on morphological opening/closing and thresholded morphological correlation demonstrates the best change detection result.

Darkening effect on AZ31B magnesium alloy surface induced by nanosecond pulse Nd:YAG laser

NASA Astrophysics Data System (ADS)

Guan, Y. C.; Zhou, W.; Zheng, H. Y.; Li, Z. L.

2013-09-01

Permanent darkening effect was achieved on surface of AZ31B Mg alloy irradiated with nanosecond pulse Nd:YAG laser, and special attention was made to examine how surface structure as well as oxidation affect the darkening effect. Experiments were carried out to characterize morphological evolution and chemical composition of the irradiated areas by optical reflection spectrometer, Talysurf surface profiler, SEM, EDS, and XPS. The darkening effect was found to be occurred at the surface under high laser energy. Optical spectra showed that the induced darkening surface was uniform over the spectral range from 200 nm to 1100 nm. SEM and surface profiler showed that surface morphology of darkening areas consisted of large number of micron scale cauliflower-like clusters and protruding particles. EDS and XPS showed that compared to non-irradiated area, oxygen content at the darkening areas increased significantly. It was proposed a mechanism that involved trapping of light in the surface morphology and chemistry variation of irradiated areas to explain the laser-induced darkening effect on AZ31B Mg alloy.

Investigation on large-area fabrication of vivid shark skin with superior surface functions

NASA Astrophysics Data System (ADS)

Chen, Huawei; Zhang, Xin; Ma, Lingxi; Che, Da; Zhang, Deyuan; Sudarshan, T. S.

2014-10-01

Shark skin has attracted worldwide attention because of its superior drag reduction, antifouling performance induced from its unique surface morphology. Although the vivid shark skin has been fabricated by a bio-replicated micro-imprinting approach in previous studies and superior drag reduction effect has been validated in water tunnel, continuous large-area fabrication is still an obstacle to wide apply. In this paper, one novel bio-replication coating technology is proposed for large-area transfer of shark skin based on rapid UV curable paint. Apart from design of coating system, bio-replication accuracy of surface morphology was validated about 97% by comparison between shark skin template and coating surface morphology. Finally, the drag reduction and anti-fouling function of coating surface were tested in water tunnel and open algae pond respectively. Drag reduction rate of coating surface was validated about 12% higher and anti-fouling was proved to about hundred times ameliorate, all of which are more excellent than simple 2D riblet surface.

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.

The Comprehensive AOCMF Classification: Skull Base and Cranial Vault Fractures – Level 2 and 3 Tutorial

PubMed Central

Ieva, Antonio Di; Audigé, Laurent; Kellman, Robert M.; Shumrick, Kevin A.; Ringl, Helmut; Prein, Joachim; Matula, Christian

2014-01-01

The AOCMF Classification Group developed a hierarchical three-level craniomaxillofacial classification system with increasing level of complexity and details. The highest level 1 system distinguish four major anatomical units, including the mandible (code 91), midface (code 92), skull base (code 93), and cranial vault (code 94). This tutorial presents the level 2 and more detailed level 3 systems for the skull base and cranial vault units. The level 2 system describes fracture location outlining the topographic boundaries of the anatomic regions, considering in particular the endocranial and exocranial skull base surfaces. The endocranial skull base is divided into nine regions; a central skull base adjoining a left and right side are divided into the anterior, middle, and posterior skull base. The exocranial skull base surface and cranial vault are divided in regions defined by the names of the bones involved: frontal, parietal, temporal, sphenoid, and occipital bones. The level 3 system allows assessing fracture morphology described by the presence of fracture fragmentation, displacement, and bone loss. A documentation of associated intracranial diagnostic features is proposed. This tutorial is organized in a sequence of sections dealing with the description of the classification system with illustrations of the topographical skull base and cranial vault regions along with rules for fracture location and coding, a series of case examples with clinical imaging and a general discussion on the design of this classification. PMID:25489394

Molecular chirality and domain shapes in lipid monolayers on aqueous surfaces

NASA Astrophysics Data System (ADS)

Krüger, Peter; Lösche, Mathias

2000-11-01

The shapes of domain boundaries in the mesoscopic phase separation of phospholipids in aqueous surface monolayers are analyzed with particular attention to the influence of molecular chirality. We have calculated equilibrium shapes of such boundaries, and show that the concept of spontaneous curvature-derived from an effective pair potential between the chiral molecules-yields an adequate description of the contribution of chirality to the total energy of the system. For enantiomeric dipalmitoylphosphatidylcholine in pure monolayers, and in mixtures with impurities that adsorb preferentially at the (one-dimensional) boundary line between the isotropic and anisotropic fluid phases, such as cyanobiphenyl (5CB), a total energy term that includes line tension, electrostatic dipole-dipole interaction, and spontaneous curvature is sufficient to describe the shapes of well-separated domain boundaries in full detail. As soon as interdomain distances fall below the domain sizes upon compression of a monolayer, fluctuations take over in determining its detailed structural morphology. Using Minkowski measures for the well-studied dimyristoyl phosphatidic acid (DMPA)/cholesterol system, we show that calculations accounting for line tension, electrostatic repulsion, and molecular chirality yield boundary shapes that are of the same topology as the experimentally observed structures. At a fixed molecular area in the phase coexistence region, the DMPA/cholesterol system undergoes an exponential decay of the line tension λ with decreasing subphase temperature T.

Multilayered Polysaccharide Nanofilms for Controlled Delivery of Pentoxifylline and Possible Treatment of Chronic Venous Ulceration.

PubMed

Stana, Jan; Stergar, Janja; Gradišnik, Lidija; Flis, Vojko; Kargl, Rupert; Fröhlich, Eleonore; Stana Kleinschek, Karin; Mohan, Tamilselvan; Maver, Uroš

2017-09-11

Local drug delivery systems made from nontoxic polysaccharide nanofilms have an enormous potential in wound care. A detailed understanding of the structural, surface, physicochemical, and cytotoxic properties of such systems is crucial to design clinically efficacious materials. Herein, we fabricated polysaccharide-based nanofilms onto either a 2D model (SiO 2 and Au sensors) or on nonwoven alginate 3D substrates using an alternating assembly of N,N,N-trimethylchitosan (TMC) and alginic acid (ALG) by a spin-assisted layer-by-layer (LbL) technique. These TMC/ALG multilayered nanofilms are used for a uniform encapsulation and controlled release of pentoxifylline (PTX), a potent anti-inflammatory drug for treatment of the chronic venous ulceration. We show a tailorable film growth and mass, morphology, as well as surface properties (charge, hydrophilicity, porosity) of the assembled nanofilms through control of the coating during the spin-assisted assembly. The uniform distribution of the encapsulated PTX in the TMC/ALG nanofilms is preserved even with when the amount of the incorporated PTX increases. The PTX release mechanism from the model and real systems is studied in detail and is very comparable for both systems. Finally, different cell-based assays illustrated the potential of the TMC/ALG multilayer system in wound care (e.g., treatment chronic venous ulceration) applications, including a decrease of TNF-α secretion, a common indicator of inflammation.

CoFlame: A refined and validated numerical algorithm for modeling sooting laminar coflow diffusion flames

NASA Astrophysics Data System (ADS)

Eaves, Nick A.; Zhang, Qingan; Liu, Fengshan; Guo, Hongsheng; Dworkin, Seth B.; Thomson, Murray J.

2016-10-01

Mitigation of soot emissions from combustion devices is a global concern. For example, recent EURO 6 regulations for vehicles have placed stringent limits on soot emissions. In order to allow design engineers to achieve the goal of reduced soot emissions, they must have the tools to so. Due to the complex nature of soot formation, which includes growth and oxidation, detailed numerical models are required to gain fundamental insights into the mechanisms of soot formation. A detailed description of the CoFlame FORTRAN code which models sooting laminar coflow diffusion flames is given. The code solves axial and radial velocity, temperature, species conservation, and soot aggregate and primary particle number density equations. The sectional particle dynamics model includes nucleation, PAH condensation and HACA surface growth, surface oxidation, coagulation, fragmentation, particle diffusion, and thermophoresis. The code utilizes a distributed memory parallelization scheme with strip-domain decomposition. The public release of the CoFlame code, which has been refined in terms of coding structure, to the research community accompanies this paper. CoFlame is validated against experimental data for reattachment length in an axi-symmetric pipe with a sudden expansion, and ethylene-air and methane-air diffusion flames for multiple soot morphological parameters and gas-phase species. Finally, the parallel performance and computational costs of the code is investigated.

Relationships between tensile strength, morphology and crystallinity of treated kenaf bast fibers

NASA Astrophysics Data System (ADS)

Sosiati, H.; Rohim, Ar; Ma`arif, Triyana, K.; Harsojo

2013-09-01

Surface treatments on kenaf bast fibers were carried out with steam, alkali and a combination of steam-alkali. To verify and gain an understanding of their inter-relationship, tensile strength, surface morphology and crystallinity of treated and raw fibers were characterized. Tensile strength of fibers was measured with a universal tensile machine (UTM), crystallinity was estimated using X-ray diffraction (XRD) and Fourier transformation infrared (FTIR) spectroscopy, and surface morphology was examined by scanning electron microscopy (SEM). Tensile strength of the treated fibers was higher than that of the raw fiber. Tensile strength increased after steam treatment and was further improved by alkali treatment, but slightly reduced after steam treatment followed by alkalization. Increase of concentration of alkali tended to increase tensile strength. Differences in tensile strength of the treated fibers are discussed in relation to the changes in surface morphology and crystallinity. Understanding of these relationships may provide direction towards the goal of producing better performance of natural fiber composites.

Observations from the High Resolution Imaging Science Experiment (HiRISE): Martian dust devils in Gusev and Russell craters

NASA Astrophysics Data System (ADS)

Verba, Circe A.; Geissler, Paul E.; Titus, Timothy N.; Waller, Devin

2010-09-01

Two areas targeted for repeated imaging by detailed High Resolution Imaging Science Experiment (HiRISE) observations allow us to examine morphological differences and monitor seasonal variations of Martian dust devil tracks at two quite different locations. Russell crater (53.3°S, 12.9°E) is regularly imaged to study seasonal processes including deposition and sublimation of CO2 frost. Gusev crater (14.6°S, 175.4°E) has been frequently imaged in support of the Mars Exploration Rover mission. Gusev crater provides the first opportunity to compare “ground truth” orbital observations of dust devil tracks to surface observations of active dust plumes. Orbital observations show that dust devil tracks are rare, forming at a rate <1/110 that of the occurrence of active dust plumes estimated from Spirit's surface observations. Furthermore, the tracks observed from orbit are wider than typical plume diameters observed by Spirit. We conclude that the tracks in Gusev are primarily formed by rare, large dust devils. Smaller dust devils fail to leave tracks that are visible from orbit, perhaps because of limited surface excavation depths. Russell crater displays more frequent, smaller sinuous tracks than Gusev. This may be due to the thin dust cover in Russell, allowing smaller dust devils to penetrate through the bright dust layer and leave conspicuous tracks. The start of the dust devil season and peak activity are delayed in Russell in comparison to Gusev, likely because of its more southerly location. Dust devils in both sites travel in directions consistent with general circulation model (GCM)-predicted winds, confirming a laboratory-derived approach to determining dust devil travel directions based on track morphology.

Morphology Effect of Vertical Graphene on the High Performance of Supercapacitor Electrode.

PubMed

Zhang, Yu; Zou, Qionghui; Hsu, Hua Shao; Raina, Supil; Xu, Yuxi; Kang, Joyce B; Chen, Jun; Deng, Shaozhi; Xu, Ningsheng; Kang, Weng P

2016-03-23

Graphene and its composites are widely investigated as supercapacitor electrodes due to their large specific surface area. However, the severe aggregation and disordered alignment of graphene sheets hamper the maximum utilization of its surface area. Here we report an optimized structure for supercapacitor electrode, i.e., the vertical graphene sheets, which have a vertical structure and open architecture for ion transport pathway. The effect of morphology and orientation of vertical graphene on the performance of supercapacitor is examined using a combination of model calculation and experimental study. Both results consistently demonstrate that the vertical graphene electrode has a much superior performance than that of lateral graphene electrode. Typically, the areal capacitances of a vertical graphene electrode reach 8.4 mF/cm(2) at scan rate of 100 mV/s; this is about 38% higher than that of a lateral graphene electrode and about 6 times higher than that of graphite paper. To further improve its performance, a MnO2 nanoflake layer is coated on the surface of graphene to provide a high pseudocapacitive contribution to the overall areal capacitance which increases to 500 mF/cm(2) at scan rate of 5 mV/s. The reasons for these significant improvements are studied in detail and are attributed to the fast ion diffusion and enhanced charge storage capacity. The microscopic manipulation of graphene electrode configuration could greatly improve its specific capacitance, and furthermore, boost the energy density of supercapacitor. Our results demonstrate that the vertical graphene electrode is more efficient and practical for the high performance energy storage device with high power and energy densities.

Stereo and scanning electron microscopy of in-shell Brazil nut (Bertholletia excelsa H.B.K.): part two-surface sound nut fungi spoilage susceptibility.

PubMed

Scussel, Vildes M; Manfio, Daniel; Savi, Geovana D; Moecke, Elisa H S

2014-11-01

This work reports the in-shell Brazil nut spoilage susceptible morpho-histological characteristics and fungi infection (shell, edible part, and brown skin) through stereo and scanning electron microscopies (SEM). The following characteristics related to shell (a) morphology-that allow fungi and insects' entrance to inner nut, and (b) histology-that allow humidity absorption, improving environment conditions for living organisms development, were identified. (a.1) locule in testae-the nut navel, which is a cavity formed during nut detaching from pods (located at 1.0 to 2.0/4th of the shell B&C nut faces linkage). It allows the nut brown skin (between shell and edible part) first contact to the external environment, through the (a.2) nut channel-the locule prolongation path, which has the water/nutrients cambium function for their transport and distribution to the inner seed (while still on the tree/pod). Both, locule followed by the channel, are the main natural entrance of living organisms (fungi and insects), including moisture to the inner seed structures. In addition, the (a.3) nut shell surface-which has a crinkled and uneven surface morphology-allows water absorption, thus adding to the deterioration processes too. The main shell histological characteristic, which also allows water absorption (thus improving environment conditions for fungi proliferation), is the (b.1) cell wall porosity-the multilayered wall and porous rich cells that compose the shell faces double tissue layers and the (b.2) soft tissue-the mix of tissues 2 faces corner/linkage. This work also shows in details the SEM nut spoilage susceptible features highly fungi infected with hyphae and reproductive structures distribution. © 2014 Institute of Food Technologists®

Combined use of FE-SEM+EDS, ToF-SIMS, XPS, XRD and OM for the study of ancient gilded artefacts

NASA Astrophysics Data System (ADS)

Ingo, G. M.; Riccucci, C.; Pascucci, M.; Messina, E.; Giuliani, C.; Biocca, P.; Tortora, L.; Fierro, G.; Di Carlo, G.

2018-07-01

Gilded brooches dating back to 16th-17th centuries CE were investigated by means of integrated and complementary analytical techniques such as high spatial resolution field emission scanning electron microscopy coupled with energy dispersive X-ray spectrometry (FE-SEM+EDS), time of flight secondary ion mass spectrometry (ToF-SIMS), X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD) and optical microscopy (OM). The results reveal in detail the surface and subsurface morphology and the chemical features of the micrometric decorative Au layer that has been deposited by means of the so-called fire-gilding technique based on the use of an amalgam. Moreover, the results allow to recognise chlorine, sulphur and phosphorous species as the main degradation agents and to identify the corrosion products naturally formed during the long-term interaction with the burial soil constituents. The findings show also that the galvanic coupling between the two dissimilar metals, i.e. Cu and Au, lead to enhancement of corrosion phenomena causing the spalling of the gold thin film and the disfigurement of the object. From a conservation point of view, the results suggest a targeted use of low-toxic inhibitors to hinder the detrimental role of chlorine as possible responsible of future further severe degradation phenomena. In conclusions, the micro and nano-chemical, structural and morphological investigations in a depth range from a few nanometers to micrometers have revealed the complex nature of corroded surface of ancient gold coated artefacts, highlighting some specific aspects related to their peculiar degradation mechanisms thus extending the scientific relevance of the tailored use of complementary and integrated surface and subsurface analytical techniques for the investigation of ancient coated artefacts.

The Effect of Bi on the Selective Oxide Formation on CMnSi TRIP Steel

NASA Astrophysics Data System (ADS)

Oh, Jonghan; Cho, Lawrence; Kim, Myungsoo; Kang, Kichul; De Cooman, Bruno C.

2016-11-01

The effect of Bi addition on the selective oxidation and the galvanizability of CMnSi transformation-induced plasticity (TRIP) steels was studied by hot dip galvanizing laboratory simulations. Bi-added TRIP steels were intercritically annealed at 1093 K (820 °C) and galvanized in a 0.22 wt pct Al-containing Zn bath. The oxide morphology was investigated by scanning electron microscopy, transmission electron microscopy, and 3D atom probe tomography. Bi formed a Bi-enriched surface layer during the intercritical annealing. A decrease of the oxygen permeability was observed with increasing Bi addition. The internal oxidation was suppressed in Bi-added CMnSi TRIP steel. The surface oxide morphology was changed from a continuous layer morphology to a more lens-shaped morphology. The galvanizability of the Bi-added TRIP steel was improved by the combination of the change of the oxide morphology and the dissolution of the Bi-enriched surface layer during immersion of the strip in the Zn bath.

Effects of surface morphology on the optical and electrical properties of Schottky diodes of CBD deposited ZnO nanostructures

NASA Astrophysics Data System (ADS)

Mwankemwa, Benard S.; Akinkuade, Shadrach; Maabong, Kelebogile; Nel, Jackie M.; Diale, Mmantsae

2018-04-01

We report on effect of surface morphology on the optical and electrical properties of chemical bath deposited Zinc oxide (ZnO) nanostructures. ZnO nanostructures were deposited on the seeded conducting indium doped tin oxide substrate positioned in three different directions in the growth solution. Field emission scanning electron microscopy was used to evaluate the morphological properties of the synthesized nanostructures and revealed that the positioning of the substrate in the growth solution affects the surface morphology of the nanostructures. The optical absorbance, photoluminescence and Raman spectroscopy of the resulting nanostructures are discussed. The electrical characterization of the Schottky diode such as barrier height, ideality factor, rectification ratios, reverse saturation current and series resistance were found to depend on the nanostructures morphology. In addition, current transport mechanism in the higher forward bias of the Schottky diode was studied and space charge limited current was found to be the dominant transport mechanism in all samples.

Effects of polymer surface energy on morphology and properties of silver nanowire fabricated via nanoimprint and E-beam evaporation

NASA Astrophysics Data System (ADS)

Zhao, Zhi-Jun; Hwang, Soon Hyoung; Jeon, Sohee; Jung, Joo-Yun; Lee, Jihye; Choi, Dae-Geun; Choi, Jun-Hyuk; Park, Sang-Hu; Jeong, Jun-Ho

2017-10-01

In this paper, we demonstrate that use of different nanoimprint resins as a polymer pattern has a significant effect on the morphology of silver (Ag) nanowires deposited via an E-beam evaporator. RM-311 and Ormo-stamp resins are chosen as a polymer pattern to form a line with dimensions of width (100 nm) × space (100 nm) × height (120 nm) by using nanoimprint lithography (NIL). Their contact angles are then measured to evaluate their surface energies. In order to compare the properties of the Ag nanowires deposited on the various polymer patterns with different surface energies, hydrophobic surface treatment of the polymer pattern surface is implemented using self-assembled monolayers. In addition, gold and aluminum nanowires are fabricated for comparison with the Ag nanowires, with the differences in the nanowire morphologies being determined by the different atomic properties. The monocrystalline and polycrystalline structures of the various Ag nanowire formations are observed using transmission electron microscopy. In addition, the melting temperatures and optical properties of four kinds of Ag nanowire morphologies deposited on various polymer patterns are evaluated using a hot plate and an ultraviolet-visible (UV-vis) spectrometer, respectively. The results indicate that the morphology of the Ag nanowire determines the melting temperature and the transmission. We believe that these findings will greatly aid the development of NIL, along with physical evaporation and chemical deposition techniques, and will be widely employed in optics, biology, and surface wettability applications.

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.

A simple distributed sediment delivery approach for rural catchments

NASA Astrophysics Data System (ADS)

Reid, Lucas; Scherer, Ulrike

2014-05-01

The transfer of sediments from source areas to surface waters is a complex process. In process based erosion models sediment input is thus quantified by representing all relevant sub processes such as detachment, transport and deposition of sediment particles along the flow path to the river. A successful application of these models requires, however, a large amount of spatially highly resolved data on physical catchment characteristics, which is only available for a few, well examined small catchments. For the lack of appropriate models, the empirical Universal Soil Loss Equation (USLE) is widely applied to quantify the sediment production in meso to large scale basins. As the USLE provides long-term mean soil loss rates, it is often combined with spatially lumped models to estimate the sediment delivery ratio (SDR). In these models, the SDR is related to data on morphological characteristics of the catchment such as average local relief, drainage density, proportion of depressions or soil texture. Some approaches include the relative distance between sediment source areas and the river channels. However, several studies showed that spatially lumped parameters describing the morphological characteristics are only of limited value to represent the factors of influence on sediment transport at the catchment scale. Sediment delivery is controlled by the location of the sediment source areas in the catchment and the morphology along the flow path to the surface water bodies. This complex interaction of spatially varied physiographic characteristics cannot be adequately represented by lumped morphological parameters. The objective of this study is to develop a simple but spatially distributed approach to quantify the sediment delivery ratio by considering the characteristics of the flow paths in a catchment. We selected a small catchment located in in an intensively cultivated loess region in Southwest Germany as study area for the development of the SDR approach. The flow pathways were extracted in a geographic information system. Then the sediment delivery ratio for each source area was determined using an empirical approach considering the slope, morphology and land use properties along the flow path. As a benchmark for the calibration of the model parameters we used results of a detailed process based erosion model available for the study area. Afterwards the approach was tested in larger catchments located in the same loess region.

Comparative analysis between Payen and Daedalia Planum lava fields

NASA Astrophysics Data System (ADS)

Giacomini, Lorenza; Massironi, Matteo; Pasquarè, Giorgio; Carli, Cristian; Martellato, Elena; Frigeri, Alessandro; Cremonese, Gabriele; Bistacchi, Andrea; Federico, Costanzo

The Payen volcanic complex is a large Quaternary fissural structure belonging to the back-arc extensional area of the Andes in the Mendoza Province (Argentina). From the eastern portion of this volcanic structure huge pahoehoe lava flows were emitted, extending more than 180 km from the feeding vents. These huge flows propagated over the nearly flat surface of the Pampean foreland (ca 0.3° slope). The very low viscosity of the olivine basalt lavas, coupled with the inflation process are the most probable explanation for their considerable length. In an inflation process a thin viscoelastic crust, produced at an early stage, is later inflated by the underlying fluid core, which remains hot and fluid thanks to the thermal-shield effect of the crust. The inflation shows some typical morphological fingerprints like tumuli, lava lobes, lava rises and lava ridges. In order to compare the morphology of the Argentinean Payen flows with lava flows on Mars, MOLA, THEMIS, MOC, MRO/HIRISE, and MEX/OMEGA data have been analysed, providing a multi-scale characterisation of Martian flows. Mars Global Surveyor/MOLA data were used to investigate the topographic environment over which flows propagated on Mars in order to detect very low angle slopes where possibly inflation processes could have developed. Then Mars Odyssey/THEMIS and Mars Global Surveyor's MOC data were used to detect Martian lava flows with inflation "fingerprints", whereas OMEGA data were used to obtain some inferences about their composition. Finally the MRO/HIRISE images recently acquired, can provide further details and constraints on surface morphologies and lava fronts. All these data were used to analyze Daedalia Planum lava field, at about 300 km southwest of Arsia Mons, and clear morphological similarities with the longest flows of the Payen lava fields were found. These striking morphological analogies suggest that inflation process is quite common also for the Daedalia field. This is also supported by simple calculation of effusion rates for not inflated lava flows foreseeing for the Daedalia Planum long lava flows improbable huge rates. Consequently lower effusion rates coupled with very efficient spreading process are more likely. Nonetheless the comparison of typology vs frequency and dimension of inflation related features of Payen and Daedalia Planum field suggest that even the effusion rates responsible of inflated flows on Mars are by far higher than the one on the Earth.

Experimental impact crater morphology

NASA Astrophysics Data System (ADS)

Dufresne, A.; Poelchau, M. H.; Hoerth, T.; Schaefer, F.; Thoma, K.; Deutsch, A.; Kenkmann, T.

2012-04-01

The research group MEMIN (Multidisciplinary Experimental and Impact Modelling Research Network) is conducting impact experiments into porous sandstones, examining, among other parameters, the influence of target pore-space saturation with water, and projectile velocity, density and mass, on the cratering process. The high-velocity (2.5-7.8 km/s) impact experiments were carried out at the two-stage light-gas gun facilities of the Fraunhofer Institute EMI (Germany) using steel, iron meteorite (Campo del Cielo IAB), and aluminium projectiles with Seeberg Sandstone as targets. The primary objectives of this study within MEMIN are to provide detailed morphometric data of the experimental craters, and to identify trends and characteristics specific to a given impact parameter. Generally, all craters, regardless of impact conditions, have an inner depression within a highly fragile, white-coloured centre, an outer spallation (i.e. tensile failure) zone, and areas of arrested spallation (i.e. spall fragments that were not completely dislodged from the target) at the crater rim. Within this general morphological framework, distinct trends and differences in crater dimensions and morphological characteristics are identified. With increasing impact velocity, the volume of craters in dry targets increases by a factor of ~4 when doubling velocity. At identical impact conditions (steel projectiles, ~5km/s), craters in dry and wet sandstone targets differ significantly in that "wet" craters are up to 76% larger in volume, have depth-diameter ratios generally below 0.19 (whereas dry craters are almost consistently above this value) at significantly larger diameters, and their spallation zone morphologies show very different characteristics. In dry craters, the spall zone surfaces dip evenly at 10-20° towards the crater centre. In wet craters, on the other hand, they consist of slightly convex slopes of 10-35° adjacent to the inner depression, and of sub-horizontal tensile failure planes ("terraces") in the outer, near-surface region of the crater. We suggest that these differences are due to a reduction in tensile strength in pore-space saturated sandstone. Linking morphological characteristics to impact conditions might provide a tool to help reconstruct impact conditions in small, more strength- than gravity-dominated impact craters in nature. Findings in small-scale experiments can aid the identification of particular structures in the field, such as spallation induced uplift of strata outside of the crater margins.

The Devil is in the Details: Using X-Ray Computed Tomography to Develop Accurate 3D Grain Characteristics and Bed Structure Metrics for Gravel Bed Rivers

NASA Astrophysics Data System (ADS)

Voepel, H.; Hodge, R. A.; Leyland, J.; Sear, D. A.; Ahmed, S. I.

2014-12-01

Uncertainty for bedload estimates in gravel bed rivers is largely driven by our inability to characterize the arrangement and orientation of the sediment grains within the bed. The characteristics of the surface structure are produced by the water working of grains, which leads to structural differences in bedforms through differential patterns of grain sorting, packing, imbrication, mortaring and degree of bed armoring. Until recently the technical and logistical difficulties of characterizing the arrangement of sediment in 3D have prohibited a full understanding of how grains interact with stream flow and the feedback mechanisms that exist. Micro-focus X-ray CT has been used for non-destructive 3D imaging of grains within a series of intact sections of river bed taken from key morphological units (see Figure 1). Volume, center of mass, points of contact, protrusion and spatial orientation of individual surface grains are derived from these 3D images, which in turn, facilitates estimates of 3D static force properties at the grain-scale such as pivoting angles, buoyancy and gravity forces, and grain exposure. By aggregating representative samples of grain-scale properties of localized interacting sediment into overall metrics, we can compare and contrast bed stability at a macro-scale with respect to stream bed morphology. Understanding differences in bed stability through representative metrics derived at the grain-scale will ultimately lead to improved bedload estimates with reduced uncertainty and increased understanding of interactions between grain-scale properties on channel morphology. Figure 1. CT-Scans of a water worked gravel-filled pot. a. 3D rendered scan showing the outer mesh, and b. the same pot with the mesh removed. c. vertical change in porosity of the gravels sampled in 5mm volumes. Values are typical of those measured in the field and lab. d. 2-D slices through the gravels at 20% depth from surface (porosity = 0.35), and e. 75% depth from surface (porosity = 0.24), showing the presence of fine sediments 'mortaring' the larger gravels. f. shows a longitudinal slide from which pivot angle measurements can be determined for contact points between particles. g. Example of two particle extraction from the CT scan showing how particle contact areas can be measured (dark area).

Morphology-dependent low-frequency Raman scattering in ultrathin spherical, cubic, and cuboid SnO2 nanocrystals

NASA Astrophysics Data System (ADS)

Liu, L. Z.; Wu, X. L.; Li, T. H.; Xiong, S. J.; Chen, H. T.; Chu, Paul K.

2011-12-01

Nanoscale spherical, cubic, and cuboid SnO2 nanocrystals (NCs) are used to investigate morphology-dependent low-frequency Raman scattering. A double-peak structure in which the linewidths and energy separation between two subpeaks decrease with increasing sizes of cuboid NCs is observed and attributed to the surface acoustic phonon modes confined in three dimensional directions and determined by the surface/interface compositions. The decrease in energy separation is due to weaker coupling between the acoustic modes in different vibration directions. Our experimental and theoretical studies clearly disclose the morphology-dependent surface vibrational behavior in self-assembled NCs.

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.

Inheritance of Occlusal Topography: A Twin Study

PubMed Central

Su, C-Y.; Corby, P.M.; Elliot, M.A.; Studen-Pavlovich, D.A.; Ranalli, D.N.; Rosa, B.; Wessel, J.; Schork, N.J.; Hart, T.C.; Bretz, W.A.

2011-01-01

Aim This was to determine the relative contribution of genetic factors on the morphology of occlusal surfaces of mandibular primary first molars by employing the twin study model. Methods The occlusal morphology of mandibular primary first molar teeth from dental casts of 9 monozygotic (MZ) twin pairs and 12 dizygotic (DZ) twin pairs 4 to 7 years old, were digitized by contact-type three-dimensional (3D) scanner. To compare the similarity of occlusal morphology between twin sets, each twin pair of occlusal surfaces was superimposed to establish the best fit by using computerized least squared techniques. Heritability was computed using a variance component model, adjusted for age and gender. Results DZ pairs demonstrated a greater degree of occlusal morphology variance. The total amount of difference in surface overlap was 0.0508 mm (0.0018 (inches) for the MZ (n=18) sample and 0.095 mm (0.0034 inches) for the DZ (n=24) sample and were not statistically significant (p=0.2203). The transformed mean differences were not statistically significantly different (p=0.2203). Heritability estimates of occlusal surface areas for right and left mandibular primary first molars were 97.5% and 98.2% (p<0.0001), respectively. Conclusions Occlusal morphology of DZ twin pairs was more variable than that of MZ twin pairs. Heritability estimates revealed that genetic factors strongly influence occlusal morphology of mandibular primary first molars. PMID:18328234

Method of making controlled morphology metal-oxides

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

Ozcan, Soydan; Lu, Yuan

2016-05-17

A method of making metal oxides having a preselected morphology includes preparing a suspension that includes a solvent, polymeric nanostructures having multiplicities of hydroxyl surface groups and/or carboxyl surface groups, and a metal oxide precursor. The suspension has a preselected ratio of the polymeric nanostructures to the metal oxide precursor of at least 1:3, the preselected ratio corresponding to a preselected morphology. Subsequent steps include depositing the suspension onto a substrate, removing the solvent to form a film, removing the film from the substrate, and annealing the film to volatilize the polymeric nanostructures and convert the metal oxide precursor tomore » metal oxide nanoparticles having the preselected morphology or to a metal oxide nanosheet including conjoined nanoparticles having the preselected morphology.« less

Study of Chemistry and Structure-Property Relationship on Tunable Plasmonic Nanostructures

NASA Astrophysics Data System (ADS)

Jing, Hao

In this dissertation, the rational design and controllable fabrication of an array of novel plasmonic nanostructures with geometrically tunable optical properties are demonstrated, including metal-semiconductor hybrid hetero-nanoparticles, bimetallic noble metal nanoparticles and hollow nanostructures (nanobox and nanocage). Firstly, I have developed a robust wet chemistry approach to the geometry control of Ag-Cu2O core-shell nanoparticles through epitaxial growth of Cu2O nanoshells on the surfaces of various Ag nanostructures, such as quasi-spherical nanoparticles, nanocubes, and nanocuboids. Precise control over the core and the shell geometries enables me to develop detailed, quantitative understanding of how the Cu2O nanoshells introduce interesting modifications to the resonance frequencies and the extinction spectral line shapes of multiple plasmon modes of the Ag cores. Secondly, I present a detailed and systematic study of the controlled overgrowth of Pd on Au nanorods. The overgrowth of Pd nanoshells with fine-controlled dimensions and architectures on single-crystalline Au nanorods through seed-mediated growth protocol in the presence of various surfactants is investigated. Thirdly, I have demonstrated that creation of high-index facets on subwavelength metallic nanoparticles provides a unique approach to the integration of desired plasmonic and catalytic properties on the same nanoparticle. Through site-selective surface etching of metallic nanocuboids whose surfaces are dominated by low-index facets, I have controllably fabricated nanorice and nanodumbbell particles, which exhibit drastically enhanced catalytic activities arising from the catalytically active high index facets abundant on the particle surfaces. And the nanorice and nanodumbbell particles also possess appealing tunable plasmonic properties that allow us to gain quantitative insights into nanoparticle-catalyzed reactions with unprecedented sensitivity and detail through time-resolved plasmon-enhanced spectroscopic measurements, such as surface-enhanced Raman scattering (SERS). Last but not least, I have demonstrated that the capability of geometry control over Ag-Pd bimetallic hollow nanostructures through nanoscale galvanic replacement can be greatly enhanced by the use of appropriate mild reducing agents, such as ascorbic acid and formaldehyde. With the aid of mild reducing agents, we have been able to fine-tailor the compositions, interior architectures, and surface morphologies of Ag-Pd bimetallic hollow nanoparticles with increased structural complexity through surface ligand-free galvanic replacement processes at room temperature. This reducing agent-mediated galvanic replacement provides a unique way of achieving both enhanced optical tunability and optimized catalytic activities through deliberate control over the geometries of complex Ag-Pd bimetallic nanoparticles.

Characterization of the surface properties of MgO using paper spray mass spectrometry.

PubMed

Zheng, Yajun; Zhang, Xiaoling; Bai, Zongquan; Zhang, Zhiping

2016-08-01

Significant advances have been made in the preparation of different morphologies of magnesium oxide (MgO), but the relationship between MgO morphology and its interactions with therapeutic drugs is rarely studied. Herein, we investigated the interactions between different morphologies of MgO and therapeutic drugs using paper spray mass spectrometry. Different morphologies of MgO including trapezoidal, needle-like, flower-like and nest-like structures were prepared through a facile precipitation method. The as-obtained MgO particles were then coated onto the surface of filter paper via vacuum filtration strategy. The coated papers with different morphologies of MgO were used as the substrates for paper spray mass spectrometry to explore the interactions between different MgO and therapeutic drugs. Through investigating the interactions between different morphologies of MgO coated papers and therapeutic drugs, it demonstrated that, in contrast to the trapezoidal, needle-like and nest-like MgO coated papers, different drugs in dried blood spots (DBS) were more favourably eluted off from the paper coated with flower-like MgO due to its weaker surface basicity. Also, the signal intensities of different drugs during paper spray were highly dependent on their elution behaviours. Paper spray mass spectrometry (MS) provides an avenue to elaborate the surface properties of MgO with different structures. The surface basicity of MgO played a crucial role in determining the elution behaviours of therapeutic drugs in DBS, and a more favourable elution behaviour tended to result in a higher MS signal. Copyright © 2016 John Wiley & Sons, Ltd. Copyright © 2016 John Wiley & Sons, Ltd.

Peering to the Heart of Massive Star Birth - II. A Survey of 8 Protostars

NASA Astrophysics Data System (ADS)

Tan, Jonathan

2012-10-01

We propose to follow-up our SOFIA FORCAST Basic Science observation of G35.20-0.74 with similar observations of seven other massive protostars, with a total time request of about 5 hours. Our goal is to use mid-infrared (MIR) and far-infrared (FIR) imaging, especially at wavelengths of 31 and 37 microns that are unique to SOFIA, to constrain detailed radiative transfer models of massive star formation. In particular, we show that if massive stars are forming from high mass surface density cores, then the observed MIR and FIR morphologies are strongly influenced by the presence of protostellar outflow cavities. For typical surface densities of ~1 g cm^2, the observed radiation at wavelengths less than about 30 microns escapes preferentially along the near-facing outflow cavity. At longer wavelengths we begin to see emission from the far-facing cavity, and thus the proposed SOFIA FORCAST observations are particularly powerful for constraining the properties of the star-forming core such as the mass surface density in the immediate vicinity of the protostar. Our full analysis will involve comparing these SOFIA FORCAST data with images at other wavelengths, including Spitzer IRAC (3 to 8 microns), ground-based (10 & 20 microns) and Herschel (70 microns), to derive flux profiles and spectral energy distributions as a function of projected distance along the outflow axis. These observations have the potential to: (1) test basic scenarios of massive star formation; (2) begin to provide detailed measurements such as the mass surface density structure of massive star-forming cores and the line-of-sight orientation, opening angle, degree of symmetry and dust content of their outflow cavities. With a sample of eight protostars in total we will begin to be able to search for trends in these properties with core mass surface density and protostellar luminosity.

Nanocomposites of AgInZnS and graphene nanosheets as efficient photocatalysts for hydrogen evolution

NASA Astrophysics Data System (ADS)

Tang, Xiaosheng; Chen, Weiwei; Zu, Zhiqiang; Zang, Zhigang; Deng, Ming; Zhu, Tao; Sun, Kuan; Sun, Lidong; Xue, Junmin

2015-11-01

In this study, AgInZnS-reduced graphene (AIZS-rGO) nanocomposites with tunable band gap absorption and large specific surface area were synthesized by a simple hydrothermal route, which showed highly efficient photocatalytic hydrogen evolution under visible-light irradiation. The relationships between their crystal structures, morphology, surface chemical states and photocatalytic activity have been explored in detail. Importantly, the AIZS-rGO nanocomposites with 0.02 wt% of graphene exhibited the highest hydrogen production rate of 1.871 mmol h-1 g-1, which was nearly 2 times the hydrogen production rate when using pure AIZS nanoparticles as the photocatalyst. This high photocatalytic H2-production activity was attributed predominantly to the incorporation of graphene sheets, which demonstrated an obvious influence on the structure and optical properties of the AIZS nanoparticles. In the AIZS-rGO nanocomposites, graphene could not only serve as an effective supporting layer but also is a recombination center for conduction band electrons and valence band holes. It is believed that this kind of graphene-based material would attract much attention as a promising photocatalyst with a high efficiency and a low cost for photocatalytic H2 evolution and facilitates their application in the environmental protection field.In this study, AgInZnS-reduced graphene (AIZS-rGO) nanocomposites with tunable band gap absorption and large specific surface area were synthesized by a simple hydrothermal route, which showed highly efficient photocatalytic hydrogen evolution under visible-light irradiation. The relationships between their crystal structures, morphology, surface chemical states and photocatalytic activity have been explored in detail. Importantly, the AIZS-rGO nanocomposites with 0.02 wt% of graphene exhibited the highest hydrogen production rate of 1.871 mmol h-1 g-1, which was nearly 2 times the hydrogen production rate when using pure AIZS nanoparticles as the photocatalyst. This high photocatalytic H2-production activity was attributed predominantly to the incorporation of graphene sheets, which demonstrated an obvious influence on the structure and optical properties of the AIZS nanoparticles. In the AIZS-rGO nanocomposites, graphene could not only serve as an effective supporting layer but also is a recombination center for conduction band electrons and valence band holes. It is believed that this kind of graphene-based material would attract much attention as a promising photocatalyst with a high efficiency and a low cost for photocatalytic H2 evolution and facilitates their application in the environmental protection field. Electronic supplementary information (ESI) available. See DOI: 10.1039/c5nr05145b

Some aspects of lithological and exogenic control of sandstone morphology, the Świętokrzyskie (Holy Cross) Mts. case study, Poland

NASA Astrophysics Data System (ADS)

Urban, Jan; Górnik, Marek

2017-10-01

Various morphologies of cliffs built of different quartzose rocks in the Świętokrzyskie (Holy Cross) Mts. (upland region, central Poland) - from Cambrian quartzites and Devonian quartzitic sandstones to Triassic and Jurassic porous sandstones - were described in order to examine the constraints of their lithological and spatial occurrence. The quantitative study of the occurrence of these morphologies on cliffs makes it possible to distinguish two principal groups of morphologies: angular relief produced by rock splitting (crumbling), typical of quartzites indurated in silica and of open porosity less than 1.5%, and morphologies developed due to granular disintegration and exfoliation of sandstones of open porosity higher than 1.5%. Among the relief types of this second group, morphology reflecting sedimentary and diagenetic structures as well as smooth surfaces are the most common and are referred to sandstones of a wide range of porosity, whereas honeycombs and surfaces suffering fast granular decay and scaling are characteristic of rocks of specific porosity (respectively: 5-8% and 3.5-8%). The occurrence of honeycombs on rock surfaces is also conditioned by exogenic factors: sun, wind and rain, since this morphology tends to occur on cliffs with aspects ranging from south-east, through south, to west-north-west.

Solution pans and linear sand bedforms on the bare-rock limestone shelf of the Campeche Bank, Yucatán Peninsula, Mexico

NASA Astrophysics Data System (ADS)

Goff, John A.; Gulick, Sean P. S.; Cruz, Ligia Perez; Stewart, Heather A.; Davis, Marcy; Duncan, Dan; Saustrup, Steffen; Sanford, Jason; Fucugauchi, Jaime Urrutia

2016-04-01

A high-resolution, near-surface geophysical survey was conducted in 2013 on the Campeche Bank, a carbonate platform offshore of Yucatán, Mexico, to provide a hazard assessment for future scientific drilling into the Chicxulub impact crater. It also provided an opportunity to obtain detailed information on the seafloor morphology and shallow stratigraphy of this understudied region. The seafloor exhibited two morphologies: (1) small-scale (<2 m) bare-rock karstic features, and (2) thin (<1 m) linear sand accumulations overlying the bedrock. Solution pans, circular to oblong depressions featured flat bottoms and steep sides, were the dominant karstic features; they are known to form subaerially by the pooling of rainwater and dissolution of carbonate. Observed pans were 10-50 cm deep and generally 1-8 m wide, but occasionally reach 15 m, significantly larger than any solution pan observed on land (maximum 6 m). These features likely grew over the course of many 10's of thousands of years in an arid environment while subaerially exposed during lowered sea levels. Surface sands are organized into linear bedforms oriented NE-SW, 10's to 100's meters wide, and kilometers long. These features are identified as sand ribbons (longitudinal bedforms), and contained asymmetric secondary transverse bedforms that indicate NE-directed flow. This orientation is incompatible with the prevalent westward current direction; we hypothesize that these features are storm-generated.

Nanostructured zinc oxide photoelectrodes by green routes M-SILAR and electrodeposition for dye sensitized solar cell

NASA Astrophysics Data System (ADS)

Gaikwad, M. A.; Suryawanshi, M. P.; Maldar, P. S.; Dongale, T. D.; Moholkar, A. V.

2018-04-01

Surfactant-free, ultrasound assisted modified successive ionic layer adsorption and reaction (M-SILAR) method and home-made microcontroller based low-cost potentiostat system are employed to prepare zinc oxide (ZnO) nanostructure based thin films. The comparison between physicochemical as well as photoelectrochemical (PEC) properties of the nanostructures prepared via two different template free, simplistic and cost-effective green routes have been discussed in detail. X-ray diffraction and Raman analysis confirm the formation of phase pure ZnO with the hexagonal crystal structure. Surface morphology significantly affects the physicochemical as well as PEC properties of ZnO thin films. Nanorods (NRs) and nanosheets (NSs) based ZnO thin films sensitized with N3 dye have been directly used as photoelectrodes in the dye-sensitized solar cell (DSSC). The power conversion efficiency (PCE) of 0.59% is achieved with Jsc of 4.04 mA/cm2 and Voc of 0.44 V for the DSSC in which the M-SILAR deposited 1-D ZnO NRs based thin film is used as the photoanode. While relatively less PCE of 0.29% with Jsc of 2.53 mA/cm2 and Voc of 0.36 V is obtained for DSSC prepared using electrodeposited 2-D ZnO NSs. In the NSs like 2-D surface morphology, the presence of multiple grain boundaries are acted as traps for the diffusing electrons, which reduces the electron mobility through it.

Crater Morphology of Engineered and Natural Impactors into Planetary Ice

NASA Astrophysics Data System (ADS)

Danner, M.; Winglee, R.; Koch, J.

2017-12-01

Crater morphology of engineered impactors, such as those proposed for the Europa Kinetic Ice Penetrator (EKIP) mission, varies drastically from that of natural impactors (i.e. Asteroids, meteoroids). Previous work of natural impact craters in ice have been conducted with the intent to bound the thickness of Europa's ice crust; this work focuses on the depth, size, and compressional effects caused by various impactor designs, and the possible effects to the Europan surface. The present work details results from nine projectiles that were dropped on the Taku Glacier, AK at an altitude of 775 meters above surface; three rocks to simulate natural impactors, and six iterations of engineered steel and aluminum penetrator projectiles. Density measurements were taken at various locations within the craters, as well as through a cross section of the crater. Due to altitude restrictions, projectiles remained below terminal velocity. The natural/rock impact craters displayed typical cratering characteristics such as shallow, half meter scale depth, and orthogonal compressional forcing. The engineered projectiles produced impact craters with depths averaging two meters, with crater widths matching the impactor diameters. Compressional waves from the engineered impactors propagated downwards, parallel to direction of impact. Engineered impactors create significantly less lateral fracturing than natural impactors. Due to the EKIP landing mechanism, sampling of pristine ice closer to the lander is possible than previously thought with classical impact theory. Future work is planned to penetrate older, multiyear ice with higher velocity impacts.

Anthropometric Analysis of the Face.

PubMed

Zacharopoulos, Georgios V; Manios, Andreas; Kau, Chung H; Velagrakis, George; Tzanakakis, George N; de Bree, Eelco

2016-01-01

Facial anthropometric analysis is essential for planning cosmetic and reconstructive facial surgery, but has not been available in detail for modern Greeks. In this study, multiple measurements of the face were performed on young Greek males and females to provide a complete facial anthropometric profile of this population and to compare its facial morphology with that of North American Caucasians. Thirty-one direct facial anthropometric measurements were obtained from 152 Greek students. Moreover, the prevalence of the various face types was determined. The resulting data were compared with those published regarding North American Caucasians. A complete set of average anthropometric data was obtained for each sex. Greek males, when compared to Greek females, were found to have statistically significantly longer foreheads as well as greater values in morphologic face height, mandible width, maxillary surface arc distance, and mandibular surface arc distance. In both sexes, the most common face types were mesoprosop, leptoprosop, and hyperleptoprosop. Greek males had significantly wider faces and mandibles than the North American Caucasian males, whereas Greek females had only significantly wider mandibles than their North American counterparts. Differences of statistical significance were noted in the head and face regions among sexes as well as among Greek and North American Caucasians. With the establishment of facial norms for Greek adults, this study contributes to the preoperative planning as well as postoperative evaluation of Greek patients that are, respectively, scheduled for or are to be subjected to facial reconstructive and aesthetic surgery.

An Ingenious Super Light Trapping Surface Templated from Butterfly Wing Scales

NASA Astrophysics Data System (ADS)

Han, Zhiwu; Li, Bo; Mu, Zhengzhi; Yang, Meng; Niu, Shichao; Zhang, Junqiu; Ren, Luquan

2015-08-01

Based on the super light trapping property of butterfly Trogonoptera brookiana wings, the SiO2 replica of this bionic functional surface was successfully synthesized using a simple and highly effective synthesis method combining a sol-gel process and subsequent selective etching. Firstly, the reflectivity of butterfly wing scales was carefully examined. It was found that the whole reflectance spectroscopy of the butterfly wings showed a lower level (less than 10 %) in the visible spectrum. Thus, it was confirmed that the butterfly wings possessed a super light trapping effect. Afterwards, the morphologies and detailed architectures of the butterfly wing scales were carefully investigated using the ultra-depth three-dimensional (3D) microscope and field emission scanning electronic microscopy (FESEM). It was composed by the parallel ridges and quasi-honeycomb-like structure between them. Based on the biological properties and function above, an exact SiO2 negative replica was fabricated through a synthesis method combining a sol-gel process and subsequent selective etching. At last, the comparative analysis of morphology feature size and the reflectance spectroscopy between the SiO2 negative replica and the flat plate was conducted. It could be concluded that the SiO2 negative replica inherited not only the original super light trapping architectures, but also the super light trapping characteristics of bio-template. This work may open up an avenue for the design and fabrication of super light trapping materials and encourage people to look for more super light trapping architectures in nature.

Chemical and Morphological Inhomogeneity of Aluminum Metal and Oxides from Soft X-ray Spectromicroscopy

DOE PAGES

Altman, Alison B.; Pemmaraju, C. Das; Alayoglu, Selim; ...

2017-05-04

Oxygen and aluminum K-edge X-ray absorption spectroscopy (XAS), imaging from a scanning transmission X-ray microscope (STXM), and first-principles calculations were used to probe the composition and morphology of bulk aluminum metal, α- and γ-Al 2 O 3 , and several types of aluminum nanoparticles. The imaging results agreed with earlier transmission electron microscopy studies that showed a 2 to 5 nm thick layer of Al 2 O 3 on all the Al surfaces. Spectral interpretations were guided by examination of the calculated transition energies, which agreed well with the spectroscopic measurements. The features we observed in the experimental O andmore » Al K-edge XAS were used to determine the chemical structure and phase of the Al 2 O 3 on the aluminum surfaces. For unprotected 18 and 100 nm Al nanoparticles, this analysis revealed an oxide layer that was similar to γ-Al 2 O 3 and comprised of both tetrahedral and octahedral Al coordination sites. For oleic acid-protected Al nanoparticles, only tetrahedral Al oxide coordination sites were observed. Our results were correlated to trends in the reactivity of the different materials, which suggests that the structures of different Al 2 O 3 layers have an important role in the accessibility of the underlying Al metal toward further oxidation. Combined, the Al K-edge XAS and STXM results provided detailed chemical information that was not obtained from powder X-ray diffraction or imaging from a transmission electron microscope.« less

Mechanistic Selection and Growth of Twinned Bicrystalline Primary Si in Near Eutectic Al-Si Alloys

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

Jung, Choonho

2006-01-01

Morphological evolution and selection of angular primary silicon is investigated in near-eutectic Al-Si alloys. Angular silicon arrays are grown directionally in a Bridgman furnace at velocities in the regime of 10 -3 m/sec and with a temperature gradient of 7.5 x 10 3 K/m. Under these conditions, the primary Si phase grows as an array of twinned bicrystalline dendrites, where the twinning gives rise to a characteristic 8-pointed star-shaped primary morphology. While this primary Si remains largely faceted at the growth front, a complex structure of coherent symmetric twin boundaries enables various adjustment mechanisms which operate to optimize the characteristicmore » spacings within the primary array. In the work presented here, this primary silicon growth morphology is examined in detail. In particular, this thesis describes the investigation of: (1) morphological selection of the twinned bicrystalline primary starshape morphology; (2) primary array behavior, including the lateral propagation of the starshape grains and the associated evolution of a strong <100> texture; (3) the detailed structure of the 8-pointed star-shaped primary morphology, including the twin boundary configuration within the central core; (4) the mechanisms of lateral propagation and spacing adjustment during array evolution; and (5) the thermosolutal conditions (i.e. operating state) at the primary growth front, including composition and phase fraction in the vicinity of the primary tip.« less

Catalysts for electrochemical generation of oxygen

NASA Technical Reports Server (NTRS)

Hagans, P.; Yeager, E.

1979-01-01

Several aspects of the electrolytic evolution of oxygen for use in life support systems are analyzed including kinetic studies of various metal and nonmetal electrode materials, the formation of underpotential films on electrodes, and electrode surface morphology and the use of single crystal metals. In order to investigate the role of surface morphology to electrochemical reactions, a low energy electron diffraction and an Auger electron spectrometer are combined with an electrochemical thin-layer cell allowing initial characterization of the surface, reaction run, and then a comparative surface analysis.

Study of Carbon Nanotubes as Etching Masks and Related Applications in the Surface Modification of GaAs-based Light-Emitting Diodes.

PubMed

Jin, Yuanhao; Li, Qunqing; Chen, Mo; Li, Guanhong; Zhao, Yudan; Xiao, Xiaoyang; Wang, Jiaping; Jiang, Kaili; Fan, Shoushan

2015-09-02

The surface modification of LEDs based on GaAs is realized by super-aligned multiwalled carbon nanotube (SACNT) networks as etching masks. The surface morphology of SACNT networks is transferred to the GaAs. It is found that the light output power of LEDs based on GaAs with a nanostructured surface morphology is greatly enhanced with the electrical power unchanged. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

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.