Effect of surface roughness of trench sidewalls on electrical properties in 4H-SiC trench MOSFETs

NASA Astrophysics Data System (ADS)

Kutsuki, Katsuhiro; Murakami, Yuki; Watanabe, Yukihiko; Onishi, Toru; Yamamoto, Kensaku; Fujiwara, Hirokazu; Ito, Takahiro

2018-04-01

The effects of the surface roughness of trench sidewalls on electrical properties have been investigated in 4H-SiC trench MOSFETs. The surface roughness of trench sidewalls was well controlled and evaluated by atomic force microscopy. The effective channel mobility at each measurement temperature was analyzed on the basis of the mobility model including optical phonon scattering. The results revealed that surface roughness scattering had a small contribution to channel mobility, and at the arithmetic average roughness in the range of 0.4-1.4 nm, there was no correlation between the experimental surface roughness and the surface roughness scattering mobility. On the other hand, the characteristics of the gate leakage current and constant current stress time-dependent dielectric breakdown tests demonstrated that surface morphology had great impact on the long-term reliability of gate oxides.

Tin doped indium oxide anodes with artificially controlled nano-scale roughness using segregated Ag nanoparticles for organic solar cells

NASA Astrophysics Data System (ADS)

Kim, Hyo-Joong; Ko, Eun-Hye; Noh, Yong-Jin; Na, Seok-In; Kim, Han-Ki

2016-09-01

Nano-scale surface roughness in transparent ITO films was artificially formed by sputtering a mixed Ag and ITO layer and wet etching of segregated Ag nanoparticles from the surface of the ITO film. Effective removal of self-segregated Ag particles from the grain boundaries and surface of the crystalline ITO film led to a change in only the nano-scale surface morphology of ITO film without changes in the sheet resistance and optical transmittance. A nano-scale rough surface of the ITO film led to an increase in contact area between the hole transport layer and the ITO anode, and eventually increased the hole extraction efficiency in the organic solar cells (OSCs). The heterojunction OSCs fabricated on the ITO anode with a nano-scale surface roughness exhibited a higher power conversion efficiency of 3.320%, than that (2.938%) of OSCs made with the reference ITO/glass. The results here introduce a new method to improve the performance of OSCs by simply modifying the surface morphology of the ITO anodes.

Effect of resin infiltration and microabrasion on the microhardness, surface roughness and morphology of incipient carious lesions.

PubMed

Yazkan, Basak; Ermis, R Banu

2018-02-15

The effects of resin infiltration and microabrasion on incipient carious lesions by surface microhardness, roughness and morphological assessments, and resistance to further acid attack of treated lesions were evaluated. Eighty artificially-induced incipient lesions were randomly divided into five groups (n = 16): resin infiltration with an adhesive resin (Excite F, Ivoclar Vivadent, Schaan, Liechtenstein), resin infiltration with a resin infiltrant (Icon, DMG, Hamburg, Germany), microabrasion without polishing (Opalustre, Ultradent, South Jordan, UT, USA), microabrasion with polishing (Opalustre, Ultradent, Diamond Excel, FGM, Joinville, SC, Brazil), and distilled water (control group). All specimens were exposed to demineralization for another 10 d. Microhardness, roughness and morphological assessments were done at baseline, following initial demineralization, treatment and further demineralization. Data were analysed by the Kruskal-Wallis, Friedman's and Bonferroni tests (p < .05). Enamel lesions treated with resin infiltrant and microabrasion demonstrated similar hardness values, with a nonsignificant difference compared with sound enamel. Resin infiltration demonstrated lower roughness values than those of microabrasion, and the values did not reach the values of sound enamel. Further demineralization for 10 d did not affect the hardness but increased the roughness of infiltrated and microabraded enamel surfaces. Polishing did not influence the roughness of microabraded enamel surfaces. After resin infiltration, porosities on enamel were sealed completely. The surface structure was similar to that of the enamel conditioning pattern for microabraded enamel lesions. Within the limitations of this study, the icon infiltration and microabrasion technique appeared to be effective for improving microhardness. Icon appeared to provide reduced roughness, although not equal to sound enamel. Further research is needed to elucidate their clinical relevance.

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

PubMed

Hong, Jinkee; Kang, Sang Wook

2011-09-01

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

Rough SERS substrate based on gold coated porous silicon layer prepared on the silicon backside surface

NASA Astrophysics Data System (ADS)

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

2017-04-01

We report in this paper a novel method to elaborate rough Surface Enhanced Raman Scattering (SERS) substrate. A single layer of porous silicon was formed on the silicon backside surface. Morphological characteristics of the porous silicon layer before and after gold deposition were influenced by the rough character (gold size). The reflectance measurements showed a dependence of the gold nano-grains size on the surface nature, through the Localized Surface Plasmon (LSP) band properties. SERS signal of Rhodamine 6G used as a model analyte, adsorbed on the rough porous silicon layer revealed a marked enhancement of its vibrational modes intensities.

The effect of brushing with toothpaste containing nano calcium carbonate upon nanofill composite resin surface roughness

NASA Astrophysics Data System (ADS)

Ramadhani, A. M.; Herda, E.; Triaminingsih, S.

2017-08-01

This study aims to determine the effect of brushing with toothpaste containing nanocalcium carbonate on the roughness of nanofill composite resin surface. Brushing was conducted with 3 types of materials for 3 consecutive brushing periods of 10 minutes each. Surface roughness was measured using a surface-roughness tester and the results were analyzed using the repeated ANOVA and the one-way ANOVA test. The surface morphology was observed using SEM after 3 months’ worth of brushing with the 3 materials. It was found that the nanofill composite resin surface-roughness value increased significantly (p<0.005) after brushing with toothpaste containing nano calcium carbonate for 3 months, but the value was not as high as that obtained when brushing with other types of toothpaste.

In vivo surface roughness evolution of a stressed metallic implant

NASA Astrophysics Data System (ADS)

Tan, Henry

2016-10-01

Implant-associated infection, a serious medical issue, is caused by the adhesion of bacteria to the surface of biomaterials; for this process the surface roughness is an important property. Surface nanotopography of medical implant devices can control the extent of bacterial attachment by modifying the surface morphology; to this end a model is introduced to facilitate the analysis of a nanoscale smooth surface subject to mechanical loading and in vivo corrosion. At nanometre scale rough surface promotes friction, hence reduces the mobility of the bacteria; this sessile environment expedites the biofilm growth. This manuscript derives the controlling equation for surface roughness evolution for metallic implant subject to in-plane stresses, and predicts the in vivo roughness changes within 6 h of continued mechanical loading at different stress level. This paper provides analytic tool and theoretical information for surface nanotopography of medical implant devices.

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

NASA Astrophysics Data System (ADS)

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

2010-12-01

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

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

NASA Astrophysics Data System (ADS)

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

2004-06-01

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

Membrane fouling in a submerged membrane bioreactor: An unified approach to construct topography and to evaluate interaction energy between two randomly rough surfaces.

PubMed

Cai, Xiang; Shen, Liguo; Zhang, Meijia; Chen, Jianrong; Hong, Huachang; Lin, Hongjun

2017-11-01

Quantitatively evaluating interaction energy between two randomly rough surfaces is the prerequisite to quantitatively understand and control membrane fouling in membrane bioreactors (MBRs). In this study, a new unified approach to construct rough topographies and to quantify interaction energy between a randomly rough particle and a randomly rough membrane was proposed. It was found that, natural rough topographies of both foulants and membrane could be well constructed by a modified two-variable Weierstrass-Mandelbrot (WM) function included in fractal theory. Spatial differential relationships between two constructed surfaces were accordingly established. Thereafter, a new approach combining these relationships, surface element integration (SEI) approach and composite Simpson's rule was deduced to calculate the interaction energy between two randomly rough surfaces in a submerged MBR. The obtained results indicate the profound effects of surface morphology on interaction energy and membrane fouling. This study provided a basic approach to investigate membrane fouling and interface behaviors. Copyright © 2017 Elsevier Ltd. All rights reserved.

Biocompatibility of modified ultra-high-molecular-weight polyethylene

NASA Astrophysics Data System (ADS)

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

2016-09-01

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

Modeling of surface roughness effects on Stokes flow in circular pipes

NASA Astrophysics Data System (ADS)

Song, Siyuan; Yang, Xiaohu; Xin, Fengxian; Lu, Tian Jian

2018-02-01

Fluid flow and pressure drop across a channel are significantly influenced by surface roughness on a channel wall. The present study investigates the effects of periodically structured surface roughness upon flow field and pressure drop in a circular pipe at low Reynolds numbers. The periodic roughness considered exhibits sinusoidal, triangular, and rectangular morphologies, with the relative roughness (i.e., ratio of the amplitude of surface roughness to hydraulic diameter of the pipe) no more than 0.2. Based upon a revised perturbation theory, a theoretical model is developed to quantify the effect of roughness on fully developed Stokes flow in the pipe. The ratio of static flow resistivity and the ratio of the Darcy friction factor between rough and smooth pipes are expressed in four-order approximate formulations, which are validated against numerical simulation results. The relative roughness and the wave number are identified as the two key parameters affecting the static flow resistivity and the Darcy friction factor.

Cellular Behavior of Human Adipose-Derived Stem Cells on Wettable Gradient Polyethylene Surfaces

PubMed Central

Ahn, Hyun Hee; Lee, Il Woo; Lee, Hai Bang; Kim, Moon Suk

2014-01-01

Appropriate surface wettability and roughness of biomaterials is an important factor in cell attachment and proliferation. In this study, we investigated the correlation between surface wettability and roughness, and biological response in human adipose-derived stem cells (hADSCs). We prepared wettable and rough gradient polyethylene (PE) surfaces by increasing the power of a radio frequency corona discharge apparatus with knife-type electrodes over a moving sample bed. The PE changed gradually from hydrophobic and smooth surfaces to hydrophilic (water contact angle, 90º to ~50º) and rough (80 to ~120 nm) surfaces as the power increased. We found that hADSCs adhered better to highly hydrophilic and rough surfaces and showed broadly stretched morphology compared with that on hydrophobic and smooth surfaces. The proliferation of hADSCs on hydrophilic and rough surfaces was also higher than that on hydrophobic and smooth surfaces. Furthermore, integrin beta 1 gene expression, an indicator of attachment, and heat shock protein 70 gene expression were high on hydrophobic and smooth surfaces. These results indicate that the cellular behavior of hADSCs on gradient surface depends on surface properties, wettability and roughness. PMID:24477265

Role of roughness parameters on the tribology of randomly nano-textured silicon surface.

PubMed

Gualtieri, E; Pugno, N; Rota, A; Spagni, A; Lepore, E; Valeri, S

2011-10-01

This experimental work is oriented to give a contribution to the knowledge of the relationship among surface roughness parameters and tribological properties of lubricated surfaces; it is well known that these surface properties are strictly related, but a complete comprehension of such correlations is still far to be reached. For this purpose, a mechanical polishing procedure was optimized in order to induce different, but well controlled, morphologies on Si(100) surfaces. The use of different abrasive papers and slurries enabled the formation of a wide spectrum of topographical irregularities (from the submicro- to the nano-scale) and a broad range of surface profiles. An AFM-based morphological and topographical campaign was carried out to characterize each silicon rough surface through a set of parameters. Samples were subsequently water lubricated and tribologically characterized through ball-on-disk tribometer measurements. Indeed, the wettability of each surface was investigated by measuring the water droplet contact angle, that revealed a hydrophilic character for all the surfaces, even if no clear correlation with roughness emerged. Nevertheless, this observation brings input to the purpose, as it allows to exclude that the differences in surface profile affect lubrication. So it is possible to link the dynamic friction coefficient of rough Si samples exclusively to the opportune set of surface roughness parameters that can exhaustively describe both height amplitude variations (Ra, Rdq) and profile periodicity (Rsk, Rku, Ic) that influence asperity-asperity interactions and hydrodynamic lift in different ways. For this main reason they cannot be treated separately, but with dependent approach through which it was possible to explain even counter intuitive results: the unexpected decreasing of friction coefficient with increasing Ra is justifiable by a more consistent increasing of kurtosis Rku.

Light emitting diode with high aspect ratio submicron roughness for light extraction and methods of forming

DOEpatents

Li, Ting [Ventura, CA

2011-04-26

The surface morphology of an LED light emitting surface is changed by applying a reactive ion etch (RIE) process to the light emitting surface. High aspect ratio, submicron roughness is formed on the light emitting surface by transferring a thin film metal hard-mask having submicron patterns to the surface prior to applying a reactive ion etch process. The submicron patterns in the metal hard-mask can be formed using a low cost, commercially available nano-patterned template which is transferred to the surface with the mask. After subsequently binding the mask to the surface, the template is removed and the RIE process is applied for time duration sufficient to change the morphology of the surface. The modified surface contains non-symmetric, submicron structures having high aspect ratio which increase the efficiency of the device.

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

PubMed Central

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

2014-01-01

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

Lithography-free glass surface modification by self-masking during dry etching

NASA Astrophysics Data System (ADS)

Hein, Eric; Fox, Dennis; Fouckhardt, Henning

2011-01-01

Glass surface morphologies with defined shapes and roughness are realized by a two-step lithography-free process: deposition of an ~10-nm-thin lithographically unstructured metallic layer onto the surface and reactive ion etching in an Ar/CF4 high-density plasma. Because of nucleation or coalescence, the metallic layer is laterally structured during its deposition. Its morphology exhibits islands with dimensions of several tens of nanometers. These metal spots cause a locally varying etch velocity of the glass substrate, which results in surface structuring. The glass surface gets increasingly rougher with further etching. The mechanism of self-masking results in the formation of surface structures with typical heights and lateral dimensions of several hundred nanometers. Several metals, such as Ag, Al, Au, Cu, In, and Ni, can be employed as the sacrificial layer in this technology. Choice of the process parameters allows for a multitude of different glass roughness morphologies with individual defined and dosed optical scattering.

Dynamic evolution of interface roughness during friction and wear processes.

PubMed

Kubiak, K J; Bigerelle, M; Mathia, T G; Dubois, A; Dubar, L

2014-01-01

Dynamic evolution of surface roughness and influence of initial roughness (S(a) = 0.282-6.73 µm) during friction and wear processes has been analyzed experimentally. The mirror polished and rough surfaces (28 samples in total) have been prepared by surface polishing on Ti-6Al-4V and AISI 1045 samples. Friction and wear have been tested in classical sphere/plane configuration using linear reciprocating tribometer with very small displacement from 130 to 200 µm. After an initial period of rapid degradation, dynamic evolution of surface roughness converges to certain level specific to a given tribosystem. However, roughness at such dynamic interface is still increasing and analysis of initial roughness influence revealed that to certain extent, a rheology effect of interface can be observed and dynamic evolution of roughness will depend on initial condition and history of interface roughness evolution. Multiscale analysis shows that morphology created in wear process is composed from nano, micro, and macro scale roughness. Therefore, mechanical parts working under very severe contact conditions, like rotor/blade contact, screws, clutch, etc. with poor initial surface finishing are susceptible to have much shorter lifetime than a quality finished parts. © Wiley Periodicals, Inc.

Micro and sub-micron surface structuring of AZ31 by laser re-melting and dimpling

NASA Astrophysics Data System (ADS)

Furlan, Valentina; Demir, Ali Gökhan; Previtali, Barbara

2015-12-01

In this work, the use of ns-pulsed fibre laser for surface structuring of AZ31 Mg alloy is investigated. Surface re-melting was employed to change surface morphology, especially in terms of surface roughness. Dimpling by percussion microdrilling was investigated to control the hole geometry.. With surface remelting mono-directional and homogeneous surfaces were obtained with Fl<500 J/cm2. Above 500 J/cm2 particle generation was observed, which induced sub-micron structure growth with nano-fibrous features. Moreover, surface roughness could be controlled below the initial value and much higher. With dimpling, transformation from gentle to strong ablation was observed at F0=10.3 J/cm2. XRD analysis was employed to link oxide growth to the surface morphology. Tensile tests were carried out to assess the damage on the mechanical properties after surface structuring.

Sputtering of rough surfaces: a 3D simulation study

NASA Astrophysics Data System (ADS)

von Toussaint, U.; Mutzke, A.; Manhard, A.

2017-12-01

The lifetime of plasma-facing components is critical for future magnetic confinement fusion power plants. A key process limiting the lifetime of the first-wall is sputtering by energetic ions. To provide a consistent modeling of the sputtering process of realistic geometries, the SDTrimSP-code has been extended to enable the processing of analytic as well as measured arbitrary 3D surface morphologies. The code has been applied to study the effect of varying the impact angle of ions on rough surfaces on the sputter yield as well as the influence of the aspect ratio of surface structures on the 2D distribution of the local sputtering yields. Depending on the surface morphologies reductions of the effective sputter yields to less than 25% have been observed in the simulation results.

Light emitting diode with high aspect ratio submicron roughness for light extraction and methods of forming

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

Li, Ting

The surface morphology of an LED light emitting surface is changed by applying a reactive ion etch (RIE) process to the light emitting surface. High aspect ratio, submicron roughness is formed on the light emitting surface by transferring a thin film metal hard-mask having submicron patterns to the surface prior to applying a reactive ion etch process. The submicron patterns in the metal hard-mask can be formed using a low cost, commercially available nano-patterned template which is transferred to the surface with the mask. After subsequently binding the mask to the surface, the template is removed and the RIE processmore » is applied for time duration sufficient to change the morphology of the surface. The modified surface contains non-symmetric, submicron structures having high aspect ratio which increase the efficiency of the device.« less

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.

Microstructure and physical properties of nano-biocomposite films based on cassava starch and laponite.

PubMed

Valencia, Germán Ayala; Luciano, Carla Giovana; Lourenço, Rodrigo Vinicius; do Amaral Sobral, Paulo José

2018-02-01

The aim of this research was to study the effects of laponite concentrations on some properties of nano-biocomposite films based on cassava starch, focusing mainly the relation between the properties of the surface microstructure and roughness, water contact angle and gloss. Nano-biocomposite films were produced by casting. We analyzed gloss, color, opacity, water contact angle, crystallinity by X-ray diffraction, and microstructure by scanning electron microscopy and atomic force microscopy. Texture parameters (energy, entropy and fractal dimension) were extracted from micrographs. We observed a great impact of laponite in the morphology of nano-biocomposite films. Texture parameters correlated with surface heterogeneity and roughness. Finally, surface roughness affected the surface hydrophilicity of nano-biocomposite films. Laponite platelets were exfoliated and/or intercalated with amylose and amylopectin chains. This research reports new information on the effects of laponite concentrations on the morphological, optical and wetting properties of nano-biocomposite films aiming future industrial applications. Copyright © 2017 Elsevier B.V. All rights reserved.

Evaluation of the surface roughness of zirconia ceramics after different surface treatments.

PubMed

Kirmali, Omer; Akin, Hakan; Kapdan, Alper

2014-08-01

This study aimed to investigate the effects of different mechanical surface treatments of pre-sintered zirconium oxide (ZrO2) in an attempt to improve its bonding potential. One hundred and twenty IPS e-max ZirCAD (Ivoclar Vivadent) pre-sintered zirconia blocks (7 mm diameter, 3 mm height) received six different surface treatments (n = 20): Group C was untreated (control); Group E was Er:YAG laser irradiated; Group N was Nd:YAG laser irradiated; Group SB was sandblasted, Group SN was sandblasted and Nd:YAG laser irradiated; and Group SE was sandblasted and Er:YAG laser irradiated. After the surface treatments, the average surface roughness (Ra, µm) of each specimen was determined with a profilometer, then all the specimens were sintered. The surface roughness values were analysed through one-way ANOVA and Tukey's test. Changes in the morphological characteristics of ZrO2 were examined through scanning electron microscopy (SEM). Sintered sandblasted, Er:YAG laser treatment, sandblasted + Er:YAG laser and sandblasted + Nd:YAG laser irradiation resulted in a rougher surface than the other treatments. Nd:YAG laser irradiation alone was not effective in altering the zirconia surface morphology.

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

PubMed Central

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

2017-01-01

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

Ion radiation albedo effect: influence of surface roughness on ion implantation and sputtering of materials

NASA Astrophysics Data System (ADS)

Li, Yonggang; Yang, Yang; Short, Michael P.; Ding, Zejun; Zeng, Zhi; Li, Ju

2017-01-01

In fusion devices, ion retention and sputtering of materials are major concerns in the selection of compatible plasma-facing materials (PFMs), especially in the context of their microstructural conditions and surface morphologies. We demonstrate how surface roughness changes ion implantation and sputtering of materials under energetic ion irradiation. Using a new, sophisticated 3D Monte Carlo (MC) code, IM3D, and a random rough surface model, ion implantation and the sputtering yields of tungsten (W) with a surface roughness varying between 0-2 µm have been studied for irradiation by 0.1-1 keV D+, He+ and Ar+ ions. It is found that both ion backscattering and sputtering yields decrease with increasing roughness; this is hereafter called the ion radiation albedo effect. This effect is mainly dominated by the direct, line-of-sight deposition of a fraction of emitted atoms onto neighboring asperities. Backscattering and sputtering increase with more oblique irradiation angles. We propose a simple analytical formula to relate rough-surface and smooth-surface results.

Copper foils with gradient structure in thickness direction and different roughnesses on two surfaces fabricated by double rolling

NASA Astrophysics Data System (ADS)

Wang, Xi-yong; Liu, Xue-feng; Zou, Wen-jiang; Xie, Jian-xin

2013-12-01

Copper foils with gradient structure in thickness direction and different roughnesses on two surfaces were fabricated by double rolling. The two surface morphologies of double-rolled copper foils are quite different, and the surface roughness values are 61 and 1095 nm, respectively. The roughness value of matt surface can meet the requirement for bonding the resin matrix with copper foils used for flexible printed circuit boards, thus may omit traditional roughening treatment; the microstructure of double-rolled copper foils demonstrates an obviously asymmetric gradient feature. From bright surface to matt surface in thickness direction, the average grain size first increases from 2.3 to 7.4 μm and then decreases to 3.6 μm; compared with conventional rolled copper foils, the double-rolled copper foils exhibit a remarkably increased bending fatigue life, and the increased range is about 16.2%.

A novel approach for quantitative evaluation of the physicochemical interactions between rough membrane surface and sludge foulants in a submerged membrane bioreactor.

PubMed

Lin, Hongjun; Zhang, Meijia; Mei, Rongwu; Chen, Jianrong; Hong, Huachang

2014-11-01

This study proposed a novel approach for quantitative evaluation of the physicochemical interactions between a particle and rough surface. The approach adopts the composite Simpson's rule to numerically calculate the double integrals in the surface element integration of these physicochemical interactions. The calculation could be achieved by a MATLAB program based on this approach. This approach was then applied to assess the physicochemical interactions between rough membrane surface and sludge foulants in a submerged membrane bioreactor (MBR). The results showed that, as compared with smooth membrane surface, rough membrane surface had a much lower strength of interactions with sludge foulants. Meanwhile, membrane surface morphology significantly affected the strength and properties of the interactions. This study showed that the newly developed approach was feasible, and could serve as a primary tool for investigating membrane fouling in MBRs. Copyright © 2014 Elsevier Ltd. All rights reserved.

Coevolution of bed surface patchiness and channel morphology: 2. Numerical experiments

USGS Publications Warehouse

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

2015-01-01

In gravel bed rivers, bed topography and the bed surface grain size distribution evolve simultaneously, but it is not clear how feedbacks between topography and grain sorting affect channel morphology. In this, the second of a pair of papers examining interactions between bed topography and bed surface sorting in gravel bed rivers, we use a two-dimensional morphodynamic model to perform numerical experiments designed to explore the coevolution of both free and forced bars and bed surface patches. Model runs were carried out on a computational grid simulating a 200 m long, 2.75 m wide, straight, rectangular channel, with an initially flat bed at a slope of 0.0137. Over five numerical experiments, we varied (a) whether an obstruction was present, (b) whether the sediment was a gravel mixture or a single size, and (c) whether the bed surface grain size feeds back on the hydraulic roughness field. Experiments with channel obstructions developed a train of alternate bars that became stationary and were connected to the obstruction. Freely migrating alternate bars formed in the experiments without channel obstructions. Simulations incorporating roughness feedbacks between the bed surface and flow field produced flatter, broader, and longer bars than simulations using constant roughness or uniform sediment. Our findings suggest that patches are not simply a by-product of bed topography, but they interact with the evolving bed and influence morphologic evolution.

Specific anion effects on copper surface through electrochemical treatment: Enhanced photoelectrochemical CO2 reduction activity of derived nanostructures induced by chaotropic anions

NASA Astrophysics Data System (ADS)

Navaee, Aso; Salimi, Abdollah

2018-05-01

Copper derivatives are the most prominent CO2 reduction electrocatalyst. Herein, the metallic copper has been electrochemically treated with some of common ionic salts such as N3bar, HPO2bar, S2bar, Fbar, Clbar, Brbar and Ibar based on the dissolution of a metallic working electrode in an aqueous solution to derive the surface roughness incorporated with nanostructures. Diverse surface morphology can be obtained when the ionic radii of anions are changed. Surface study reveals various roughness shapes based on the size and polarity of the anions, where the ions with higher ionic radii have higher impact on the Cu surface. In comparison, polyatomic oxyanion such as HPO2bar even with large ionic radii do not have enough strength to create the surface roughness than that of oxygen-free anions with large ionic radii. The photoelectrochemical behavior of the modified surfaces toward CO2 reduction is studied at a wide potential window in bicarbonate aqueous solution. Based on our investigations, treated surfaces by Ibar, Clbar and S2bargive a more surface roughness, while Ibar and N3bar offer higher catalytic activity toward CO2 reduction due to possible complexing ability of these anions with Cu cations, followed by formation of the co-catalyst semiconductor and facilitate electron transfer. This methodology can be applied to investigate the effect of ions on transition metals along with obtaining different surface morphologies tailored to different applications.

Effect of Young's Modulus and Surface Roughness on the Inter-Particle Friction of Granular Materials.

PubMed

Sandeep, Chitta Sai; Senetakis, Kostas

2018-01-31

In the study we experimentally examine the influence of elastic properties and surface morphology on the inter-particle friction of natural soil grains. The experiments are conducted with a custom-built micromechanical apparatus and the database is enhanced by testing engineered-reference grains. Naturally-occurring geological materials are characterized by a wide spectrum of mechanical properties (e.g., Young's modulus) and surface morphology (e.g., roughness), whereas engineered grains have much more consistent characteristics. Comparing to engineered materials, geological materials are found to display more pronounced initial plastic behavior during compression. Under the low normal load range applied in the study, between 1 and 5 N, we found that the frictional force is linearly correlated with the applied normal load, but we acknowledge that the data are found more scattered for natural soil grains, especially for rough and weathered materials which have inconsistent characteristics. The inter-particle coefficient of friction is found to be inversely correlated with the Young's modulus and the surface roughness. These findings are important in geophysical and petroleum engineering contents, since a number of applications, such as landslides and granular flows, hydraulic fracturing using proppants, and weathering process of cliffs, among others, can be simulated using discrete numerical methods. These methods employ contact mechanics properties at the grain scale and the inter-particle friction is one of these critical components. It is stressed in our study that friction is well correlated with the elastic and morphological characteristics of the grains.

Preparation of poly(L-lactic acid) nanofiber scaffolds with a rough surface by phase inversion using supercritical carbon dioxide.

PubMed

Yang, Ding-Zhu; Chen, Ai-Zheng; Wang, Shi-Bin; Li, Yi; Tang, Xiao-Lin; Wu, Yong-Jing

2015-06-24

Phase inversion using supercritical carbon dioxide (SC-CO2) has been widely used in the development of tissue engineering scaffolds, and particular attention has been given to obtaining desired morphology without additional post-treatments. However, the main challenge of this technique is the difficulty in generating a three-dimensional (3D) nanofiber structure with a rough surface in one step. Here, a poly(L-lactic acid) (PLLA) 3D nanofiber scaffold with a rough surface is obtained via phase inversion using SC-CO2 by carefully choosing fabrication conditions and porogens. It is found that this method can effectively modulate the structure morphology, promote the crystallization process of semicrystalline polymer, and induce the formation of rough structures on the surface of nanofibers. Meanwhile, the porogen of ammonium bicarbonate (AB) can produce a 3D structure with large pores, and porogen of menthol can improve the interconnectivity between the micropores of nanofibers. A significant increase in the fiber diameter is observed as the menthol content increases. Furthermore, the menthol may affect the mutual transition between the α' and α crystals of PLLA during the phase separation process. In addition, the results of protein adsorption, cell adhesion, and proliferation assays indicate that cells tend to have higher viability on the nanofiber scaffold. This process combines the characteristic properties of SC-CO2 and the solubility of menthol to tailor the morphology of polymeric scaffolds, which may have potential applications in tissue engineering.

Formation of different micro-morphologies from VO2 and ZnO crystallization using macro-porous silicon substrates

NASA Astrophysics Data System (ADS)

Salazar-Kuri, U.; Antúnez, E. E.; Estevez, J. O.; Olive-Méndez, Sion F.; Silva-González, N. R.; Agarwal, V.

2017-05-01

Square-shaped macropores produced by electrochemical anodization of n- and p-type Si wafers have been used as centers of nucleation to crystallize VO2 and ZnO. Substrate roughness dependent formation of different morphologies is revealed in the form of squared particles, spheres, bars and ribbons in the case of VO2 and hexagonal piles and spheres in the case of ZnO, have been observed.The presence of nano-/micro-metric crystals was studied through field emission scanning electron microscopy and energy dispersive X-ray spectroscopy mapping. Crystal structure of metal oxides was confirmed by micro-Raman spectroscopy. The growth of the different morphologies has been explained in terms of the surface free energy of a bare Si/SiO2 substrate and its modification originated from the roughness of the surface and of the walls of the porous substrates. This energy plays a crucial role on the minimization of the required energy to induce heterogeneous nucleation and crystal growth. Present work strengthens and provides an experimental evidence of roughness dependent metal oxide crystal growth with well-defined habits from pore corners and rough sides of the pore walls, similar to already reported protein crystals.

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.

Potential impacts of robust surface roughness indexes on DTM-based segmentation

NASA Astrophysics Data System (ADS)

Trevisani, Sebastiano; Rocca, Michele

2017-04-01

In this study, we explore the impact of robust surface texture indexes based on MAD (median absolute differences), implemented by Trevisani and Rocca (2015), in the unsupervised morphological segmentation of an alpine basin. The area was already object of a geomorphometric analysis, consisting in the roughness-based segmentation of the landscape (Trevisani et al. 2012); the roughness indexes were calculated on a high resolution DTM derived by means of airborne Lidar using the variogram as estimator. The calculated roughness indexes have been then used for the fuzzy clustering (Odeh et al., 1992; Burrough et al., 2000) of the basin, revealing the high informative geomorphometric content of the roughness-based indexes. However, the fuzzy clustering revealed a high fuzziness and a high degree of mixing between textural classes; this was ascribed both to the morphological complexity of the basin and to the high sensitivity of variogram to non-stationarity and signal-noise. Accordingly, we explore how the new implemented roughness indexes based on MAD affect the morphological segmentation of the studied basin. References Burrough, P.A., Van Gaans, P.F.M., MacMillan, R.A., 2000. High-resolution landform classification using fuzzy k-means. Fuzzy Sets and Systems 113, 37-52. Odeh, I.O.A., McBratney, A.B., Chittleborough, D.J., 1992. Soil pattern recognition with fuzzy-c-means: application to classification and soil-landform interrelationships. Soil Sciences Society of America Journal 56, 505-516. Trevisani, S., Cavalli, M. & Marchi, L. 2012, "Surface texture analysis of a high-resolution DTM: Interpreting an alpine basin", Geomorphology, vol. 161-162, pp. 26-39. Trevisani, S. & Rocca, M. 2015, "MAD: Robust image texture analysis for applications in high resolution geomorphometry", Computers and Geosciences, vol. 81, pp. 78-92.

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

Yadav, Praveen Kumar, E-mail: praveenyadav@rrcat.gov.in; Nayak, Maheswar; Rai, Sanjay Kumar

The authors report the effect of argon ion to molybdenum atom ratio (r) on the microstructure of low energy (70 eV) argon ion assisted electron beam evaporated Mo thin films. Surface roughness, morphology, and crystallinity of Mo films are found to strongly depend on “r.” Increase of “r” from 0 to 100 induces gradual loss in crystallinity, reduction in surface roughness and systematic increase in density of the film. For “r” ∼ 100, average atomic density of the film approaches the bulk value (97%) with lowest surface roughness. Further, increasing “r” up to 170 reduces the atomic density, increases roughness, and increase inmore » crystallinity induced by low energy Ar ion beam. The observed surface roughness and grain size determined by x-ray reflectivity and glancing incidence x-ray diffraction correlate well with atomic force microscopy measurements. This study demonstrates that for r = 100 one gets lowest roughness Mo film with highest density and nearly amorphous microstructure. The growth model is discussed by structural zone model.« less

Experimental and simulation study of growth of TiO2 films on different substrates and its applications

NASA Astrophysics Data System (ADS)

Ghogare, Trupti T.; Kartha, Moses J.; Kendre, Subhash D.; Pathan, Habib M.

2018-04-01

Monte-Carlo Ballistic Deposition simulations have done on substrates with different initial roughness. The grown films were observed to be porous. The initial growths of the films with seed like initiations are observed for substrate with high initial roughness. In order to confirm this effect TiO2 films were deposited on different substrates using chemical bath deposition. The surface morphological and optical properties were measured using scanning electron microscopy and a UV-Vis spectrophotometer. Flower like porous structure are obtained on glass substrate and continuous porous morphology is formed on ITO substrate. The morphology of the surfaces was successfully reconstructed and the surface porosity was calculated after digitalising images and reconstructed the surfaces. The TiO2 film formed on ITO is observed to be 10% more porous than on the film formed on glass substrate. Diffusion Limited Aggregation simulations with multiple seeds confirms that the observed flower like structure formed are due to the screening effects of the diffusing ion by already deposited particles.

Bacterial plaque retention on oral hard materials: effect of surface roughness, surface composition, and physisorbed polycarboxylate.

PubMed

McConnell, Marla D; Liu, Yu; Nowak, Andrew P; Pilch, Shira; Masters, James G; Composto, Russell J

2010-03-15

Bacterial adhesion to oral hard materials is dependent on various factors, for example, surface roughness and surface composition. In this study, bacteria retention on three oral hard substrates, hydroxyapatite (HAP), enamel, and polished enamel (p-enamel) were investigated. The surface morphology and roughness of the three substrates were measured by scanning probe microscopy. HAP had the roughest surface, followed by enamel and polished enamel. For each individual substrate type, the roughness was shown to increase with scan size up to 50 microm x 50 microm. For HAP and enamel, roughness decreased considerably after formation of a pellicle, while addition of polymer coating to the pellicle layer reduced roughness much less in comparison. Bacterial surface coverage was measured at 30 min, 3 h, and 24 h on both native and surface-modified substrates, which were coated with two different polycarboxylate-based polymers, Gantrez S97 and Carbopol 940. As a result, the polymer coated surfaces had reduced bacteria coverage compared with the native surfaces over all time points and substrates measured. The reduction is the combined effect of electrostatic repulsion and sequestering of Ca(2+) ions at the surface, which plays a key role in the initial adhesion of bacteria to enamel surfaces in models of plaque formation. (c) 2009 Wiley Periodicals, Inc.

Au-nanoparticles grafted on plasma treated PE

NASA Astrophysics Data System (ADS)

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

2010-03-01

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

Rock surface roughness measurement using CSI technique and analysis of surface characterization by qualitative and quantitative results

NASA Astrophysics Data System (ADS)

Mukhtar, Husneni; Montgomery, Paul; Gianto; Susanto, K.

2016-01-01

In order to develop image processing that is widely used in geo-processing and analysis, we introduce an alternative technique for the characterization of rock samples. The technique that we have used for characterizing inhomogeneous surfaces is based on Coherence Scanning Interferometry (CSI). An optical probe is first used to scan over the depth of the surface roughness of the sample. Then, to analyse the measured fringe data, we use the Five Sample Adaptive method to obtain quantitative results of the surface shape. To analyse the surface roughness parameters, Hmm and Rq, a new window resizing analysis technique is employed. The results of the morphology and surface roughness analysis show micron and nano-scale information which is characteristic of each rock type and its history. These could be used for mineral identification and studies in rock movement on different surfaces. Image processing is thus used to define the physical parameters of the rock surface.

Surface morphology evolution during plasma etching of silicon: roughening, smoothing and ripple formation

NASA Astrophysics Data System (ADS)

Ono, Kouichi; Nakazaki, Nobuya; Tsuda, Hirotaka; Takao, Yoshinori; Eriguchi, Koji

2017-10-01

Atomic- or nanometer-scale roughness on feature surfaces has become an important issue to be resolved in the fabrication of nanoscale devices in industry. Moreover, in some cases, smoothing of initially rough surfaces is required for planarization of film surfaces, and controlled surface roughening is required for maskless fabrication of organized nanostructures on surfaces. An understanding, under what conditions plasma etching results in surface roughening and/or smoothing and what are the mechanisms concerned, is of great technological as well as fundamental interest. In this article, we review recent developments in the experimental and numerical study of the formation and evolution of surface roughness (or surface morphology evolution such as roughening, smoothing, and ripple formation) during plasma etching of Si, with emphasis being placed on a deeper understanding of the mechanisms or plasma-surface interactions that are responsible for. Starting with an overview of the experimental and theoretical/numerical aspects concerned, selected relevant mechanisms are illustrated and discussed primarily on the basis of systematic/mechanistic studies of Si etching in Cl-based plasmas, including noise (or stochastic roughening), geometrical shadowing, surface reemission of etchants, micromasking by etch inhibitors, and ion scattering/chanelling. A comparison of experiments (etching and plasma diagnostics) and numerical simulations (Monte Carlo and classical molecular dynamics) indicates a crucial role of the ion scattering or reflection from microscopically roughened feature surfaces on incidence in the evolution of surface roughness (and ripples) during plasma etching; in effect, the smoothing/non-roughening condition is characterized by reduced effects of the ion reflection, and the roughening-smoothing transition results from reduced ion reflections caused by a change in the predominant ion flux due to that in plasma conditions. Smoothing of initially rough surfaces as well as non-roughening of initially planar surfaces during etching (normal ion incidence) and formation of surface ripples by plasma etching (off-normal ion incidence) are also presented and discussed in this context.

An Automated Road Roughness Detection from Mobile Laser Scanning Data

NASA Astrophysics Data System (ADS)

Kumar, P.; Angelats, E.

2017-05-01

Rough roads influence the safety of the road users as accident rate increases with increasing unevenness of the road surface. Road roughness regions are required to be efficiently detected and located in order to ensure their maintenance. Mobile Laser Scanning (MLS) systems provide a rapid and cost-effective alternative by providing accurate and dense point cloud data along route corridor. In this paper, an automated algorithm is presented for detecting road roughness from MLS data. The presented algorithm is based on interpolating smooth intensity raster surface from LiDAR point cloud data using point thinning process. The interpolated surface is further processed using morphological and multi-level Otsu thresholding operations to identify candidate road roughness regions. The candidate regions are finally filtered based on spatial density and standard deviation of elevation criteria to detect the roughness along the road surface. The test results of road roughness detection algorithm on two road sections are presented. The developed approach can be used to provide comprehensive information to road authorities in order to schedule maintenance and ensure maximum safety conditions for road users.

Combined control of morphology and polymorph in spray drying of mannitol for dry powder inhalation

NASA Astrophysics Data System (ADS)

Lyu, Feng; Liu, Jing J.; Zhang, Yang; Wang, Xue Z.

2017-06-01

The morphology and polymorphism of mannitol particles were controlled during spray drying with the aim of improving the aerosolization properties of inhalable dry powders. The obtained microparticles were characterized using scanning electron microscopy, infrared spectroscopy, differential scanning calorimetry, powder X-ray diffraction and inhaler testing with a next generation impactor. Mannitol particles of varied α-mannitol content and surface roughness were prepared via spray drying by manipulating the concentration of NH4HCO3 in the feed solution. The bubbles produced by NH4HCO3 led to the formation of spheroid particles with a rough surface. Further, the fine particle fraction was increased by the rough surface of carriers and the high α-mannitol content. Inhalable dry powders with a 29.1 ± 2.4% fine particle fraction were obtained by spray-drying using 5% mannitol (w/v)/2% NH4HCO3 (w/v) as the feed solution, proving that this technique is an effective method to engineer particles for dry powder inhalation.

Compositions of Mg and Se, surface morphology, roughness and Raman property of Zn1-xMgxSeyTe1-y layers grown at various substrate temperatures or dopant transport rates by MOVPE

NASA Astrophysics Data System (ADS)

Nishio, Mitsuhiro; Saito, Katsuhiko; Urata, Kensuke; Okamoto, Yasuhiro; Tanaka, Daichi; Araki, Yasuhiro; Abiru, Masakatsu; Mori, Eiichiro; Tanaka, Tooru; Guo, Qixin

2015-03-01

The growth of undoped and phosphorus (P)-doped Zn1-xMgxSeyTe1-y layers on (100) ZnTe substrates by metalorganic vapor phase epitaxy was carried out. The compositions of Mg and Se, surface morphology, roughness and Raman property were characterized as a function of substrate temperature. Not only the compositions of Mg and Se but also the crystal quality of undoped Zn1-xMgxSeyTe1-y layer strongly depended upon the substrate temperature. Furthermore, the growth of Zn1-xMgxSeyTe1-y layer nearly-lattice-matched to ZnTe substrate was achieved independent of the transport rate of trisdimethylaminophosphorus. Undoped Zn1-xMgxSeyTe1-y layer nearly-lattice-matched to ZnTe led to improvement of surface roughness. On the other hand, P doping brought about deterioration of crystalline quality.

Measurement and image processing evaluation of surface modifications of dental implants G4 pure titanium created by different techniques

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

Bulutsuz, A. G., E-mail: asligunaya@gmail.com; Demircioglu, P., E-mail: pinar.demircioglu@adu.edu.tr; Bogrekci, I., E-mail: ismail.bogrekci@adu.edu.tr

Foreign substances and organic tissue interaction placed into the jaw in order to eliminate tooth loss involves a highly complex process. Many biological reactions take place as well as the biomechanical forces that influence this formation. Osseointegration denotes to the direct structural and functional association between the living bone and the load-bearing artificial implant's surface. Taking into consideration of the requirements in the manufacturing processes of the implants, surface characterizations with high precise measurement techniques are investigated and thus long-term success of dental implant is emphasized on the importance of these processes in this study. In this research, the detailedmore » surface characterization was performed to identify the dependence of the manufacturing techniques on the surface properties by using the image processing methods and using the scanning electron microscope (SEM) for morphological properties in 3D and Taylor Hobson stylus profilometer for roughness properties in 2D. Three implant surfaces fabricated by different manufacturing techniques were inspected, and a machined surface was included into the study as a reference specimen. The results indicated that different surface treatments were strongly influenced surface morphology. Thus 2D and 3D precise inspection techniques were highlighted on the importance for surface characterization. Different image analyses techniques such as Dark-light technique were used to verify the surface measurement results. The computational phase was performed using image processing toolbox in Matlab with precise evaluation of the roughness for the implant surfaces. The relationship between the number of black and white pixels and surface roughness is presented. FFT image processing and analyses results explicitly imply that the technique is useful in the determination of surface roughness. The results showed that the number of black pixels in the image increases with increase in surface roughness.« less

Role of Integrin Subunits in Mesenchymal Stem Cell Differentiation and Osteoblast Maturation on Graphitic Carbon-coated Microstructured Surfaces

PubMed Central

Olivares-Navarrete, Rene; Rodil, Sandra E.; Hyzy, Sharon L.; Dunn, Ginger R.; Almaguer-Flores, Argelia; Schwartz, Zvi; Boyan, Barbara D.

2015-01-01

Surface roughness, topography, chemistry, and energy promote osteoblast differentiation and increase osteogenic local factor production in vitro and bone-to-implant contact in vivo, but the mechanisms involved are not well understood. Knockdown of integrin heterodimer alpha2beta1 (α2β1) blocks the osteogenic effects of the surface, suggesting signaling by this integrin homodimer is required. The purpose of the present study was to separate effects of surface chemistry and surface structure on integrin expression by coating smooth or rough titanium (Ti) substrates with graphitic carbon, retaining surface morphology but altering surface chemistry. Ti surfaces (smooth [Ra<0.4μm], rough [Ra≥3.4μm]) were sputter-coated using a magnetron sputtering system with an ultrapure graphite target, producing a graphitic carbon thin film. Human mesenchymal stem cells and MG63 osteoblast-like cells had higher mRNA for integrin subunits α1, α2, αv, and β1 on rough surfaces in comparison to smooth, and integrin αv on graphitic-carbon-coated rough surfaces in comparison to Ti. Osteogenic differentiation was greater on rough surfaces in comparison to smooth, regardless of chemistry. Silencing integrins β1, α1, or α2 decreased osteoblast maturation on rough surfaces independent of surface chemistry. Silencing integrin αv decreased maturation only on graphitic carbon-coated surfaces, not on Ti. These results suggest a major role of the integrin β1 subunit in roughness recognition, and that integrin alpha subunits play a major role in surface chemistry recognition. PMID:25770999

Scaling behavior of the surface roughness of platinum films grown by oblique angle deposition

NASA Astrophysics Data System (ADS)

Dolatshahi-Pirouz, A.; Hovgaard, M. B.; Rechendorff, K.; Chevallier, J.; Foss, M.; Besenbacher, F.

2008-03-01

Thin platinum films with well-controlled rough surface morphologies are grown by e-gun evaporation at an oblique angle of incidence between the deposition flux and the substrate normal. Atomic force microscopy is used to determine the root-mean-square value w of the surface roughness on the respective surfaces. From the scaling behavior of w , we find that while the roughness exponent α remains nearly unchanged at about 0.90, the growth exponent β changes from 0.49±0.04 to 0.26±0.01 as the deposition angle approaches grazing incidence. The values of the growth exponent β indicate that the film growth is influenced by both surface diffusion and shadowing effects, while the observed change from 0.49 to 0.26 can be attributed to differences in the relative importance of diffusion and shadowing with the deposition angle.

Correlation between surface properties and wettability of multi-scale structured biocompatible surfaces

NASA Astrophysics Data System (ADS)

Gorodzha, S. N.; Surmeneva, M. A.; Prymak, O.; Wittmar, A.; Ulbricht, M.; Epple, M.; Teresov, A.; Koval, N.; Surmenev, R. A.

2015-11-01

The influence of surface properties of radio-frequency (RF) magnetron deposited hydroxyapatite (HA) and Si-containing HA coatings on wettability was studied. The composition and morphology of the coatings fabricated on titanium (Ti) were characterized using atomic force microscopy (AFM) and X-ray diffraction (XRD). The surface wettability was studied using contact angle analysis. Different geometric parameters of acid-etched (AE) and pulse electron beam (PEB)-treated Ti substrates and silicate content in the HA films resulted in the different morphology of the coatings at micro- and nano- length scales. Water contact angles for the HA coated Ti samples were evaluated as a combined effect of micro roughness of the substrate and nano-roughness of the HA films resulting in higher water contact angles compared with acid-etched (AE) or pulse electron beam (PEB) treated Ti substrates.

Spectromicroscopy measurements of surface morphology and band structure of exfoliated graphene

NASA Astrophysics Data System (ADS)

Knox, Kevin; Locatelli, Andrea; Cvetko, Dean; Mentes, Tevfik; Nino, Miguel; Wang, Shancai; Yilmaz, Mehmet; Kim, Philip; Osgood, Richard; Morgante, Alberto

2011-03-01

Monolayer-thick crystals, such as graphene, are an area of intense interest in condensed matter research. ~However, crystal deformations in these 2D systems are known to adversely affect conductivity and increase local chemical reactivity. Additionally, surface roughness in graphene complicates band-mapping and limits resolution in techniques such as angle resolved photoemission spectroscopy (ARPES), the theory of which was developed for atomically flat surfaces. Thus, an understanding of the surface morphology of graphene is essential to making high quality devices and important for interpreting ARPES results. In this talk, we will describe a non-invasive approach to examining the corrugation in exfoliated graphene using a combination of low energy electron microscopy (LEEM) and micro-spot low energy electron diffraction (LEED). We will also describe how such knowledge of surface roughness can be used in the analysis of ARPES data to improve resolution and extract useful information about the band-structure.

Surface roughness in XeF{sub 2} etching of a-Si/c-Si(100)

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

Stevens, A.A.E.; Beijerinck, H.C.W.

2005-01-01

Single wavelength ellipsometry and atomic force microscopy (AFM) have been applied in a well-calibrated beam-etching experiment to characterize the dynamics of surface roughening induced by chemical etching of a {approx}12 nm amorphous silicon (a-Si) top layer and the underlying crystalline silicon (c-Si) bulk. In both the initial and final phase of etching, where either only a-Si or only c-Si is exposed to the XeF{sub 2} flux, we observe a similar evolution of the surface roughness as a function of the XeF{sub 2} dose proportional to D(XeF{sub 2}){sup {beta}} with {beta}{approx_equal}0.2. In the transition region from the pure amorphous to themore » pure crystalline silicon layer, we observe a strong anomalous increase of the surface roughness proportional to D(XeF{sub 2}){sup {beta}} with {beta}{approx_equal}1.5. Not only the growth rate of the roughness increases sharply in this phase, also the surface morphology temporarily changes to a structure that suggests a cusplike shape. Both features suggest that the remaining a-Si patches on the surface act effectively as a capping layer which causes the growth of deep trenches in the c-Si. The ellipsometry data on the roughness are corroborated by the AFM results, by equating the thickness of the rough layer to 6 {sigma}, with {sigma} the root-mean-square variation of the AFM's distribution function of height differences. In the AFM data, the anomalous behavior is reflected in a too small value of {sigma} which again suggests narrow and deep surface features that cannot be tracked by the AFM tip. The final phase morphology is characterized by an effective increase in surface area by a factor of two, as derived from a simple bilayer model of the reaction layer, using the experimental etch rate as input. We obtain a local reaction layer thickness of 1.5 monolayer consistent with the 1.7 ML value of Lo et al. [Lo et al., Phys. Rev. B 47, 648 (1993)] that is also independent of surface roughness.« less

Clinical Comparison of At-Home and In-Office Dental Bleaching Procedures: A Randomized Trial of a Split-Mouth Design.

PubMed

Machado, Lucas Silveira; Anchieta, Rodolfo Bruniera; dos Santos, Paulo Henrique; Briso, André Luiz; Tovar, Nick; Janal, Malvin N; Coelho, Paulo Guilherme; Sundfeld, Renato Herman

2016-01-01

The objective of this split-mouth clinical study was to compare a combination of in-office and at-home dental bleaching with at-home bleaching alone. Two applications of in-office bleaching were performed, with one appointment per week, using 38% hydrogen peroxide. At-home bleaching was performed with or without in-office bleaching using 10% carbamide peroxide in a custom-made tray every night for 2 weeks. The factor studied was the bleaching technique on two levels: Technique 1 (in-office bleaching combined with home bleaching) and Technique 2 (home bleaching only). The response variables were color change, dental sensitivity, morphology, and surface roughness. The maxillary right and left hemiarches of the participants were submitted to in-office placebo treatment and in-office bleaching, respectively (Phase 1), and at-home bleaching (Phase 2) treatment was performed on both hemiarches, characterizing a split-mouth design. Enamel surface changes and roughness were analyzed with scanning electron microscopy and optical interferometry using epoxy replicas. No statistically significant differences were observed between the bleaching techniques for either the visual or the digital analyses. There was a significant difference in dental sensitivity when both dental bleaching techniques were used, with in-office bleaching producing the highest levels of dental sensitivity after the baseline. Microscopic analysis of the morphology and roughness of the enamel surface showed no significant changes between the bleaching techniques. The two techniques produced similar results in color change, and the combination technique produced the highest levels of sensitivity. Neither technique promoted changes in morphology or surface roughness of enamel.

Slope-Velocity-Equilibrium and evolution of surface roughness on a stony hillslope

USDA-ARS?s Scientific Manuscript database

Slope-velocity equilibrium is hypothesized as a state that evolves naturally over time due to the interaction between overland flow and bed morphology, wherein steeper areas develop a relative increase in physical and hydraulic roughness such that flow velocity is a unique function of overland flow ...

Preparation of nickel oxide thin films at different annealing temperature by sol-gel spin coating method

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

Abdullah, M. A. R., E-mail: ameerridhwan89@gmail.com; Mamat, M. H., E-mail: hafiz-030@yahoo.com; Ismail, A. S., E-mail: kyrin-samaxi@yahoo.com

2016-07-06

Preparation of NiO thin films at different annealing temperature by sol-gel method was conducted to synthesize the quality of the surface thin films. The effects of annealing temperature on the surface topology were systematically investigated. Our studies confirmed that the surface roughness of the thin films was increased whenever annealing temperature was increase. NiO thin films morphology structure analysis was confirmed by field emission scanning electron microscope. Surface roughness of the thin films was investigated by atomic force microscopy.

The importance of media roughness considerations for describing particle deposition in porous media

NASA Astrophysics Data System (ADS)

Jin, C.; Emelko, M.

2016-12-01

The morphology of media/collector surfaces (i.e., roughness) is one of the most important factors that has been recognized for decades; however, literature has been, for the most part, contradictory, non-mechanistic, and non-quantitative. A one-site kinetic model for attachment/detachment using a convection-diffusion model was used to evaluate particle deposition on collector surfaces in the packed beds. Rigorous controlled experiments addressing the impacts of surface roughness on particle deposition were conducted in parallel plate and packed bed systems; they demonstrated that a) surface roughness consistently influenced colloid deposition in a nonlinear, non-monotonic manner such that a critical roughness size associated with minimum particle deposition could be identified and b) collector surface roughness and background ionic strength concurrently influenced particle deposition. Excellent agreement between experimental data and numerical simulations was found when the most current knowledge representing hydrodynamic and interfacial forces associated with collector media roughness was represented. Although surface roughness also had a non-linear, non-monotonic impact on DLVO interaction energy at all separation distances, it was inadequate for describing and simulating particle deposition on surfaces with variable roughness. Notably, this work demonstrates that hydrodynamic effects can significantly alter particle deposition relative to expectations when only the DLVO force is considered. Moreover, the combined effects of hydrodynamics and interaction forces on particle deposition on rough, spherical media are not additive, but synergistic. Consideration of hydrodynamic contributions to particle deposition may help to explain discrepancies between model-based expectations and experimental outcomes and improve descriptions of particle deposition during physicochemical filtration in systems with non-smooth collector surfaces.

Surface changes of biopolymers PHB and PLLA induced by Ar+ plasma treatment and wet etching

NASA Astrophysics Data System (ADS)

Slepičková Kasálková, N.; Slepička, P.; Sajdl, P.; Švorčík, V.

2014-08-01

Polymers, especially group of biopolymers find potential application in a wide range of disciplines due to their biodegradability. In biomedical applications these materials can be used as a scaffold or matrix. In this work, the influence of the Ar+ plasma treatment and subsequent wet etching (acetone/water) on the surface properties of polymers were studied. Two biopolymers - polyhydroxybutyrate with 8% polyhydroxyvalerate (PHB) and poly-L-lactic acid (PLLA) were used in these experiments. Modified surface layers were analyzed by different methods. Surface wettability was characterized by determination of water contact angle. Changes in elemental composition of modified surfaces were performed by X-ray Photoelectron Spectroscopy (XPS). Surface morphology and roughness was examined using Atomic Force Microscopy (AFM). Gravimetry method was used to study the mass loss. It was found that the modification from both with plasma and wet etching leads to dramatic changes of surface properties (surface chemistry, morphology and roughness). Rate of changes of these features strongly depends on the modification parameters.

A multi-directional and multi-scale roughness filter to detect lineament segments on digital elevation models - analyzing spatial objects in R

NASA Astrophysics Data System (ADS)

Baumann, Sebastian; Robl, Jörg; Wendt, Lorenz; Willingshofer, Ernst; Hilberg, Sylke

2016-04-01

Automated lineament analysis on remotely sensed data requires two general process steps: The identification of neighboring pixels showing high contrast and the conversion of these domains into lines. The target output is the lineaments' position, extent and orientation. We developed a lineament extraction tool programmed in R using digital elevation models as input data to generate morphological lineaments defined as follows: A morphological lineament represents a zone of high relief roughness, whose length significantly exceeds the width. As relief roughness any deviation from a flat plane, defined by a roughness threshold, is considered. In our novel approach a multi-directional and multi-scale roughness filter uses moving windows of different neighborhood sizes to identify threshold limited rough domains on digital elevation models. Surface roughness is calculated as the vertical elevation difference between the center cell and the different orientated straight lines connecting two edge cells of a neighborhood, divided by the horizontal distance of the edge cells. Thus multiple roughness values depending on the neighborhood sizes and orientations of the edge connecting lines are generated for each cell and their maximum and minimum values are extracted. Thereby negative signs of the roughness parameter represent concave relief structures as valleys, positive signs convex relief structures as ridges. A threshold defines domains of high relief roughness. These domains are thinned to a representative point pattern by a 3x3 neighborhood filter, highlighting maximum and minimum roughness peaks, and representing the center points of lineament segments. The orientation and extent of the lineament segments are calculated within the roughness domains, generating a straight line segment in the direction of least roughness differences. We tested our algorithm on digital elevation models of multiple sources and scales and compared the results visually with shaded relief map of these digital elevation models. The lineament segments trace the relief structure to a great extent and the calculated roughness parameter represents the physical geometry of the digital elevation model. Modifying the threshold for the surface roughness value highlights different distinct relief structures. Also the neighborhood size at which lineament segments are detected correspond with the width of the surface structure and may be a useful additional parameter for further analysis. The discrimination of concave and convex relief structures perfectly matches with valleys and ridges of the surface.

An experimental study to investigate biomechanical aspects of the initial stability of press-fit implants.

PubMed

Berahmani, Sanaz; Janssen, Dennis; van Kessel, Sal; Wolfson, David; de Waal Malefijt, Maarten; Buma, Pieter; Verdonschot, Nico

2015-02-01

Initial fixation of press-fit implants depends on interference fit, surface morphology, and bone material properties. To understand the biomechanical effect of each factor and their interactions, the pull-out strength of seven types of CoCrMo tapered implants, with four different interference fits, three different surface morphologies (low, medium and high roughness), and at two time points (0 and 30 min) were tested in trabecular bone with varying density. The effect of interference fit on pull-out strength depended on the surface morphology and time. In contrast with our expectations, samples with a higher roughness had a lower pull-out strength. We found a similar magnitude of bone damage for the different surface morphologies, but the type of damage was different, with bone compaction versus bone abrasion for low and high frictional surfaces, respectively. This explains a reduced sensitivity of fixation strength to bone mineral density in the latter group. In addition, a reduction in fixation strength after a waiting period only occurred for the low frictional specimens. Our study demonstrates that it is essential to evaluate the interplay between different factors and emphasizes the importance of testing in natural bone in order to optimize the initial stability of press-fit implants. Copyright © 2014 Elsevier Ltd. All rights reserved.

Stick-slip friction and wear of articular joints

PubMed Central

Lee, Dong Woog; Banquy, Xavier; Israelachvili, Jacob N.

2013-01-01

Stick-slip friction was observed in articular cartilage under certain loading and sliding conditions and systematically studied. Using the Surface Forces Apparatus, we show that stick-slip friction can induce permanent morphological changes (a change in the roughness indicative of wear/damage) in cartilage surfaces, even under mild loading and sliding conditions. The different load and speed regimes can be represented by friction maps—separating regimes of smooth and stick-slip sliding; damage generally occurs within the stick-slip regimes. Prolonged exposure of cartilage surfaces to stick-slip sliding resulted in a significant increase of surface roughness, indicative of severe morphological changes of the cartilage superficial zone. To further investigate the factors that are conducive to stick-slip and wear, we selectively digested essential components of cartilage: type II collagen, hyaluronic acid (HA), and glycosaminoglycans (GAGs). Compared with the normal cartilage, HA and GAG digestions modified the stick-slip behavior and increased surface roughness (wear) during sliding, whereas collagen digestion decreased the surface roughness. Importantly, friction forces increased up to 2, 10, and 5 times after HA, GAGs, and collagen digestion, respectively. Also, each digestion altered the friction map in different ways. Our results show that (i) wear is not directly related to the friction coefficient but (ii) more directly related to stick-slip sliding, even when present at small amplitudes, and that (iii) the different molecular components of joints work synergistically to prevent wear. Our results also suggest potential noninvasive diagnostic tools for sensing stick-slip in joints. PMID:23359687

Bioactive treatment promotes osteoblast differentiation on titanium materials fabricated by selective laser melting technology.

PubMed

Tsukanaka, Masako; Fujibayashi, Shunsuke; Takemoto, Mitsuru; Matsushita, Tomiharu; Kokubo, Tadashi; Nakamura, Takashi; Sasaki, Kiyoyuki; Matsuda, Shuichi

2016-01-01

Selective laser melting (SLM) technology is useful for the fabrication of porous titanium implants with complex shapes and structures. The materials fabricated by SLM characteristically have a very rough surface (average surface roughness, Ra=24.58 µm). In this study, we evaluated morphologically and biochemically the specific effects of this very rough surface and the additional effects of a bioactive treatment on osteoblast proliferation and differentiation. Flat-rolled titanium materials (Ra=1.02 µm) were used as the controls. On the treated materials fabricated by SLM, we observed enhanced osteoblast differentiation compared with the flat-rolled materials and the untreated materials fabricated by SLM. No significant differences were observed between the flat-rolled materials and the untreated materials fabricated by SLM in their effects on osteoblast differentiation. We concluded that the very rough surface fabricated by SLM had to undergo a bioactive treatment to obtain a positive effect on osteoblast differentiation.

Experimental investigation on densification behavior and surface roughness of AlSi10Mg powders produced by selective laser melting

NASA Astrophysics Data System (ADS)

Wang, Lin-zhi; Wang, Sen; Wu, Jiao-jiao

2017-11-01

Effects of laser energy density (LED) on densities and surface roughness of AlSi10Mg samples processed by selective laser melting were studied. The densification behaviors of the SLM manufactured AlSi10Mg samples at different LEDs were characterized by a solid densitometer, an industrial X-ray and CT detection system. A field emission scanning electron microscope, an automatic optical measuring system, and a surface profiler were used for measurements of surface roughness. The results show that relatively high density can be obtained with the point distance of 80-105 μm and the exposure time of 140-160 μs. The LED has an important influence on the surface morphology of the forming part, too high LED may lead to balling effect, while too low LED tends to produce defects, such as porosity and microcrack, and then affect surface roughness and porosities of the parts finally.

Texturing Carbon-carbon Composite Radiator Surfaces Utilizing Atomic Oxygen

NASA Technical Reports Server (NTRS)

Raack, Taylor

2004-01-01

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

Analysis of the Early Stages and Evolution of Dental Enamel Erosion.

PubMed

Derceli, Juliana Dos Reis; Faraoni, Juliana Jendiroba; Pereira-da-Silva, Marcelo Assumpção; Palma-Dibb, Regina Guenka

2016-01-01

The aim of this study was to evaluate by atomic force microscopy (AFM) the early phases and evolution of dental enamel erosion caused by hydrochloric acid exposure, simulating gastroesophageal reflux episodes. Polished bovine enamel slabs (4x4x2 mm) were selected and exposed to 0.1 mL of 0.01 M hydrochloric acid (pH=2) at 37 ?#61472;?#61616;C using five different exposure intervals (n=1): no acid exposure (control), 10 s, 20 s, 30 s and 40 s. The exposed area was analyzed by AFM in 3 regions to measure the roughness, surface area and morphological surface. The data were analyzed qualitatively. Roughness started as low as that of the control sample, Rrms=3.5 nm, and gradually increased at a rate of 0.3 nm/s, until reaching Rrms=12.5 nm at 30 s. After 40 s, the roughness presented increment of 0.40 nm only. Surface area (SA) increased until 20 s, and for longer exposures, the surface area was constant (at 30 s, SA=4.40 μm2 and at 40 s, SA=4.43 μm2). As regards surface morphology, the control sample presented smaller hydroxyapatite crystals (22 nm) and after 40 s the crystal size was approximately 60 nm. Short periods of exposure were sufficient to produce enamel demineralization in different patterns and the morphological structure was less affected by exposure to hydrochloric acid over 30 s.

Effect of parameters on picosecond laser ablation of Cr12MoV cold work mold steel

NASA Astrophysics Data System (ADS)

Wu, Baoye; Liu, Peng; Zhang, Fei; Duan, Jun; Wang, Xizhao; Zeng, Xiaoyan

2018-01-01

Cr12MoV cold work mold steel, which is a difficult-to-machining material, is widely used in the mold and dye industry. A picosecond pulse Nd:YVO4 laser at 1064 nm was used to conduct the study. Effects of operation parameters (i.e., laser fluence, scanning speed, hatched space and number of scans) were studied on ablation depth and quality of Cr12MoV at the repetition rate of 20 MHz. The experimental results reveal that all the four parameters affect the ablation depth significantly. While the surface roughness depends mainly on laser fluence or scanning speed and secondarily on hatched space or number of scans. For laser fluence and scanning speed, three distinct surface morphologies were observed experiencing transition from flat (Ra < 1.40 μm) to bumpy (Ra = 1.40 - 2.40 μm) eventually to rough (Ra > 2.40 μm). However, for hatched space and number of scan, there is a small bumpy and rough zone or even no rough zone. Mechanisms including heat accumulation, plasma shielding and combustion reaction effects are proposed based on the ablation depth and processing morphology. By appropriate management of the laser fluence and scanning speed, high ablation depth with low surface roughness can be obtained at small hatched space and high number of scans.

Cell behavior on surface modified polydimethylsiloxane (PDMS).

PubMed

Stanton, Morgan M; Rankenberg, Johanna M; Park, Byung-Wook; McGimpsey, W Grant; Malcuit, Christopher; Lambert, Christopher R

2014-07-01

Designing complex tissue culture systems requires cell alignment and directed extracellular matrix (ECM) and gene expression. Here, a micro-rough, polydimethylsiloxane (PDMS) surface, that also integrates a micro-pattern of 50 µm wide lines of fibronectin (FN) separated by 60 µm wide lines of bovine serum albumin (BSA), is developed. Human fibroblasts cultured on the rough, patterned substrate have aligned growth and a significant change in morphology when compared to cells on a flat, patterned surface. The rough PDMS topography significantly decreases cell area and induces the upregulation of several ECM related genes by two-fold when compared to cells cultured on flat PDMS. This study describes a simple surface engineering procedure for creating surface architecture for scaffolds to design and control the cell-surface interface. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

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).

Structure evolution of zinc oxide thin films deposited by unbalance DC magnetron sputtering

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

Aryanto, Didik, E-mail: didi027@lipi.go.id; Materials Research Group, Physics Department, Universitas Negeri Semarang, Gunungpati, Semarang 50229 Jawa Tengah; Marwoto, Putut

Zinc oxide (ZnO) thin films are deposited on corning glass substrates using unbalanced DC magnetron sputtering. The effect of growth temperature on surface morphology and crystallographic orientation of ZnO thin film is studied using atomic force microscopy (AFM) and X-ray diffraction (XRD) techniques. The surface morphology and crystallographic orientation of ZnO thin film are transformed against the increasing of growth temperature. The mean grain size of film and the surface roughness are inversely and directly proportional towards the growth temperature from room temperature to 300 °C, respectively. The smaller grain size and finer roughness of ZnO thin film are obtainedmore » at growth temperature of 400 °C. The result of AFM analysis is in good agreement with the result of XRD analysis. ZnO thin films deposited in a series of growth temperatures have hexagonal wurtzite polycrystalline structures and they exhibit transformations in the crystallographic orientation. The results in this study reveal that the growth temperature strongly influences the surface morphology and crystallographic orientation of ZnO thin film.« less

Nanostructures on fused silica surfaces produced by ion beam sputtering with Al co-deposition

NASA Astrophysics Data System (ADS)

Liu, Ying; Hirsch, Dietmar; Fechner, Renate; Hong, Yilin; Fu, Shaojun; Frost, Frank; Rauschenbach, Bernd

2018-01-01

The ion beam sputtering (IBS) of smooth mono-elemental Si with impurity co-deposition is extended to a pre-rippled binary compound surface of fused silica (SiO2). The dependence of the rms roughness and the deposited amount of Al on the distance from the Al source under Ar+ IBS with Al co-deposition was investigated on smooth SiO2, pre-rippled SiO2, and smooth Si surfaces, using atomic force microscopy and X-ray photoelectron spectroscopy. Although the amounts of Al deposited on these three surfaces all decreased with increasing distance from the Al target, the morphology and rms roughness of the smooth Si surface did not demonstrate a strong distance dependence. In contrast to smooth Si, the rms roughness of both the smooth and pre-rippled SiO2 surfaces exhibited a similar distance evolution trend of increasing, decreasing, and final stabilization at the distance where the results were similar to those obtained without Al co-deposition. However, the pre-rippled SiO2 surfaces showed a stronger modulation of rms roughness than the smooth surfaces. At the incidence angles of 60° and 70°, dot-decorated ripples and roof-tiles were formed on the smooth SiO2 surfaces, respectively, whereas nanostructures of closely aligned grains and blazed facets were generated on the pre-rippled SiO2, respectively. The combination of impurity co-deposition with pre-rippled surfaces was found to facilitate the formation of novel types of nanostructures and morphological growth. The initial ripples act as a template to guide the preferential deposition of Al on the tops of the ripples or the ripple sides facing the Al wedge, but not in the valleys between the ripples, leading to 2D grains and quasi-blazed grating, which offer significant promise in optical applications. The rms roughness enhancement is attributed not to AlSi, but to AlOxFy compounds originating mainly from the Al source.

Assessment of morphology, topography and chemical composition of water-repellent films based on polystyrene/titanium dioxide nanocomposites

NASA Astrophysics Data System (ADS)

Bolvardi, Beleta; Seyfi, Javad; Hejazi, Iman; Otadi, Maryam; Khonakdar, Hossein Ali; Drechsler, Astrid; Holzschuh, Matthias

2017-02-01

In this study, polystyrene (PS)/titanium dioxide (TiO2) films were fabricated through simple solution casting technique via a modified phase separation process. The presented approach resulted in a remarkable reduction in the required amount of nanoparticles for achieving superhydrophobicity. Scanning electron microscopy (SEM) and 3D confocal microscopy were utilized to characterize surface morphology and topography of samples, respectively. An attempt was made to give an in-depth analysis on the surface rough structure using 3D roughness profiles. It was found that high inclusions of non-solvent and nanoparticles resulted in a stable self-cleaning behavior due to the strong presence of hydrophobic TiO2 nanoparticles on the surface. Quite unexpectedly, low inclusions of nanoparticles and non-solvent also resulted in superhydrophobic property mainly due to the proper level of induced surface roughness. XPS analysis was also utilized to determine the chemical composition of the films' surfaces. The results of falling drop experiments showed that the sample containing a higher level of nanoparticles had a much lower mechanical resistance against the induced harsh conditions. All in all, the presented method has shown promising potential in fabrication of superhydrophobic surfaces with self-cleaning behavior using the lowest content of nanoparticles.

Scaling law analysis of paraffin thin films on different surfaces

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

Dotto, M. E. R.; Camargo, S. S. Jr.

2010-01-15

The dynamics of paraffin deposit formation on different surfaces was analyzed based on scaling laws. Carbon-based films were deposited onto silicon (Si) and stainless steel substrates from methane (CH{sub 4}) gas using radio frequency plasma enhanced chemical vapor deposition. The different substrates were characterized with respect to their surface energy by contact angle measurements, surface roughness, and morphology. Paraffin thin films were obtained by the casting technique and were subsequently characterized by an atomic force microscope in noncontact mode. The results indicate that the morphology of paraffin deposits is strongly influenced by substrates used. Scaling laws analysis for coated substratesmore » present two distinct dynamics: a local roughness exponent ({alpha}{sub local}) associated to short-range surface correlations and a global roughness exponent ({alpha}{sub global}) associated to long-range surface correlations. The local dynamics is described by the Wolf-Villain model, and a global dynamics is described by the Kardar-Parisi-Zhang model. A local correlation length (L{sub local}) defines the transition between the local and global dynamics with L{sub local} approximately 700 nm in accordance with the spacing of planes measured from atomic force micrographs. For uncoated substrates, the growth dynamics is related to Edwards-Wilkinson model.« less

Direct numerical simulation of flow over dissimilar, randomly distributed roughness elements: A systematic study on the effect of surface morphology on turbulence

NASA Astrophysics Data System (ADS)

Forooghi, Pourya; Stroh, Alexander; Schlatter, Philipp; Frohnapfel, Bettina

2018-04-01

Direct numerical simulations are used to investigate turbulent flow in rough channels, in which topographical parameters of the rough wall are systematically varied at a fixed friction Reynolds number of 500, based on a mean channel half-height h and friction velocity. The utilized roughness generation approach allows independent variation of moments of the surface height probability distribution function [thus root-mean-square (rms) surface height, skewness, and kurtosis], surface mean slope, and standard deviation of the roughness peak sizes. Particular attention is paid to the effect of the parameter Δ defined as the normalized height difference between the highest and lowest roughness peaks. This parameter is used to understand the trends of the investigated flow variables with departure from the idealized case where all roughness elements have the same height (Δ =0 ). All calculations are done in the fully rough regime and for surfaces with high slope (effective slope equal to 0.6-0.9). The rms roughness height is fixed for all cases at 0.045 h and the skewness and kurtosis of the surface height probability density function vary in the ranges -0.33 to 0.67 and 1.9 to 2.6, respectively. The goal of the paper is twofold: first, to investigate the possible effect of topographical parameters on the mean turbulent flow, Reynolds, and dispersive stresses particularly in the vicinity of the roughness crest, and second, to investigate the possibility of using the wall-normal turbulence intensity as a physical parameter for parametrization of the flow. Such a possibility, already suggested for regular roughness in the literature, is here extended to irregular roughness.

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.

Surface Roughness of Various Diamond-Like Carbon Films

NASA Astrophysics Data System (ADS)

Liu, Dongping; Liu, Yanhong; Chen, Baoxiang

2006-11-01

Atomic force microscopy is used to estimate and compare the surface morphology of hydrogenated and hydrogen-free diamond-like carbon (DLC) films. The films were prepared by using DC magnetron sputtering of a graphite target, pulsed cathodic carbon arcs, electron cyclotron resonance (ECR), plasma source ion implantation and dielectric barrier discharge (DBD). The difference in the surface structure is presented for each method of deposition. The influences of various discharge parameters on the film surface properties are discussed based upon the experimental results. The coalescence process via the diffusion of adsorbed carbon species is responsible for the formation of hydrogen-free DLC films with rough surfaces. The films with surface roughness at an atomic level can be deposited by energetic ion impacts in a highly ionized carbon plasma. The dangling bonds created by atomic hydrogen lead to the uniform growth of hydrocarbon species at the a-C:H film surfaces of the ECR or DBD plasmas.

Atomic force microscopy visualization of injuries in Enterococcus faecalis surface caused by Er,Cr:YSGG and diode lasers

PubMed Central

López-Jiménez, Lidia; Viñas, Miguel; Vinuesa, Teresa

2015-01-01

Aim: To visualize by Atomic Force Microscopy the alterations induced on Enterococcus. faecalis surface after treatment with 2 types of laser: Erbium chromium:yttrium-scandium-gallium-garnet (Er,Cr:YSGG) laser and Diode laser. Material and Methods: Bacterial suspensions from overnight cultures of E. faecalis were irradiated during 30 seconds with the laser-lights at 1 W and 2 W of power, leaving one untreated sample as control. Surface alterations on treated E. faecalis were visualized by Atomic Force Microscopy (AFM) and its surface roughness determined. Results: AFM imaging showed that at high potency of laser both cell morphology and surface roughness resulted altered, and that several cell lysis signs were easily visualized. Surface roughness clearly increase after the treatment with Er,Cr:YSGG at 2W of power, while the other treatments gave similar values of surface roughness. The effect of lasers on bacterial surfaces visualized by AFM revealed drastic alterations. Conclusions: AFM is a good tool to evaluate surface injuries after laser treatment; and could constitute a measure of antimicrobial effect that can complete data obtained by determination of microbial viability. Key words:Atomic force microscopy, Er,Cr:YSGG laser, diode laser, Enterococcus faecalis, surface roughness. PMID:25475770

Adhesion and proliferation of fibroblasts on RF plasma-deposited nanostructured fluorocarbon coatings: evidence of FAK activation.

PubMed

Rosso, Francesco; Marino, Gerardo; Muscariello, Livio; Cafiero, Gennaro; Favia, Pietro; D'Aloia, Erica; d'Agostino, Riccardo; Barbarisi, Alfonso

2006-06-01

We used combined plasma-deposition process to deposit smooth and nanostructured fluorocarbon coatings on polyethylenethereftalate (PET) substrates, to obtain surfaces with identical chemical composition and different roughness, and investigate the effect of surface nanostructures on adhesion and proliferation of 3T3 Swiss Albino Mouse fibroblasts. Untreated PET and polystyrene (PS) were used as controls for cell culture. We have found that the statistically significant increase of cell proliferation rate and FAK (a nonreceptor tyrosine kinase) activation detected on ROUGH fluorocarbon surfaces is due to the presence of nanostructures. Changes in cytoskeletal organization and phospho FAK (tyr 397) localization were evident after 60 min on cells adhering to ROUGH surfaces. This change was characterized by the formation of actin stress fibers along lamellar membrane protrusion instead of usual focal contacts. Also the morphology of the adhering fibroblasts (60 min) adhering on ROUGH surfaces was found quite different compared to cells adhering on smooth ones. Copyright 2006 Wiley-Liss, Inc.

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.

Addressing scale dependence in roughness and morphometric statistics derived from point cloud data.

NASA Astrophysics Data System (ADS)

Buscombe, D.; Wheaton, J. M.; Hensleigh, J.; Grams, P. E.; Welcker, C. W.; Anderson, K.; Kaplinski, M. A.

2015-12-01

The heights of natural surfaces can be measured with such spatial density that almost the entire spectrum of physical roughness scales can be characterized, down to the morphological form and grain scales. With an ability to measure 'microtopography' comes a demand for analytical/computational tools for spatially explicit statistical characterization of surface roughness. Detrended standard deviation of surface heights is a popular means to create continuous maps of roughness from point cloud data, using moving windows and reporting window-centered statistics of variations from a trend surface. If 'roughness' is the statistical variation in the distribution of relief of a surface, then 'texture' is the frequency of change and spatial arrangement of roughness. The variance in surface height as a function of frequency obeys a power law. In consequence, roughness is dependent on the window size through which it is examined, which has a number of potential disadvantages: 1) the choice of window size becomes crucial, and obstructs comparisons between data; 2) if windows are large relative to multiple roughness scales, it is harder to discriminate between those scales; 3) if roughness is not scaled by the texture length scale, information on the spacing and clustering of roughness `elements' can be lost; and 4) such practice is not amenable to models describing the scattering of light and sound from rough natural surfaces. We discuss the relationship between roughness and texture. Some useful parameters which scale vertical roughness to characteristic horizontal length scales are suggested, with examples of bathymetric point clouds obtained using multibeam from two contrasting riverbeds, namely those of the Colorado River in Grand Canyon, and the Snake River in Hells Canyon. Such work, aside from automated texture characterization and texture segmentation, roughness and grain size calculation, might also be useful for feature detection and classification from point clouds.

Surface Roughness of the Moon Derived from Multi-frequency Radar Data

NASA Astrophysics Data System (ADS)

Fa, W.

2011-12-01

Surface roughness of the Moon provides important information concerning both significant questions about lunar surface processes and engineering constrains for human outposts and rover trafficabillity. Impact-related phenomena change the morphology and roughness of lunar surface, and therefore surface roughness provides clues to the formation and modification mechanisms of impact craters. Since the Apollo era, lunar surface roughness has been studied using different approaches, such as direct estimation from lunar surface digital topographic relief, and indirect analysis of Earth-based radar echo strengths. Submillimeter scale roughness at Apollo landing sites has been studied by computer stereophotogrammetry analysis of Apollo Lunar Surface Closeup Camera (ALSCC) pictures, whereas roughness at meter to kilometer scale has been studied using laser altimeter data from recent missions. Though these studies shown lunar surface roughness is scale dependent that can be described by fractal statistics, roughness at centimeter scale has not been studied yet. In this study, lunar surface roughnesses at centimeter scale are investigated using Earth-based 70 cm Arecibo radar data and miniature synthetic aperture radar (Mini-SAR) data at S- and X-band (with wavelengths 12.6 cm and 4.12 cm). Both observations and theoretical modeling show that radar echo strengths are mostly dominated by scattering from the surface and shallow buried rocks. Given the different penetration depths of radar waves at these frequencies (< 30 m for 70 cm wavelength, < 3 m at S-band, and < 1 m at X-band), radar echo strengths at S- and X-band will yield surface roughness directly, whereas radar echo at 70-cm will give an upper limit of lunar surface roughness. The integral equation method is used to model radar scattering from the rough lunar surface, and dielectric constant of regolith and surface roughness are two dominate factors. The complex dielectric constant of regolith is first estimated globally using the regolith composition and the relation among the dielectric constant, bulk density, and regolith composition. The statistical properties of lunar surface roughness are described by the root mean square (RMS) height and correlation length, which represent the vertical and horizontal scale of the roughness. The correlation length and its scale dependence are studied using the topography data from laser altimeter observations from recent lunar missions. As these two parameters are known, surface roughness (RMS slope) can be estimated by minimizing the difference between the observed and modeled radar echo strength. Surface roughness of several regions over Oceanus Procellarum and southeastern highlands on lunar nearside are studied, and preliminary results show that maira is smoother than highlands at 70 cm scale, whereas the situation turns opposite at 12 and 4 cm scale. Surface roughness of young craters is in general higher than that of maria and highlands, indicating large rock population produced during impacting process.

Corroded surface roughness of copper analyzed by Fourier transform infrared mapping microscopy and optical profilometric study.

PubMed

Kasperek, J; Lefez, B; Beucher, E

2004-02-01

This study shows the effects of roughness on infrared spectra shapes of thin corrosion products on metallic substrates. The calculated spectra show that the baseline is mainly affected by increasing roughness and that such effects do not shift the position of the absorption bands. The model obtained has been used to extract data of artificial patina on a copper surface. Surface defects of copper substrates can be distinguished on the whole surface, from the morphological and chemical points of view, using optical profilometry and infrared microspectroscopy. An homogeneous layer of cuprite covers the surface except in the linear defects. Fourier transform infrared (FT-IR) analysis indicates that a mixture of atacamite and clinoatacamite is mainly located in these scratches. The width of these particular areas is in good agreement with profilometric observations.

Scanning electron microscopy and roughness study of dental composite degradation.

PubMed

Soares, Luís Eduardo Silva; Cortez, Louise Ribeiro; Zarur, Raquel de Oliveira; Martin, Airton Abrahão

2012-04-01

Our aim was to test the hypothesis that the use of mouthwashes, consumption of soft drinks, as well as the type of light curing unit (LCU), would change the surface roughness (Ra) and morphology of a nanofilled composite resin (Z350® 3M ESPE). Samples (80) were divided into eight groups: Halogen LCU, group 1, saliva (control); group 2, Pepsi Twist®; group 3, Listerine®; group 4, Colgate Plax®; LED LCU, group 5, saliva; group 6, Pepsi Twist®; group 7, Listerine®; group 8, Colgate Plax®. Ra values were measured at baseline, and after 7 and 14 days. One specimen of each group was prepared for scanning electron microscopy analysis after 14 days. The data were subjected to multifactor analysis of variance at a 95% confidence followed by Tukey's honestly significant difference post-hoc test. All the treatments resulted in morphological changes in composite resin surface, and the most significant change was in Pepsi Twist® groups. The samples of G6 had the greatest increase in Ra. The immersion of nanofilled resin in mouthwashes with alcohol and soft drink increases the surface roughness. Polymerization by halogen LCU (reduced light intensity) associated with alcohol contained mouthwash resulted in significant roughness on the composite.

Electrospinning of nickel oxide nanofibers: Process parameters and morphology control

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

Khalil, Abdullah, E-mail: akhalil@masdar.ac.ae; Hashaikeh, Raed, E-mail: rhashaikeh@masdar.ac.ae

2014-09-15

In the present work, nickel oxide nanofibers with varying morphology (diameter and roughness) were fabricated via electrospinning technique using a precursor composed of nickel acetate and polyvinyl alcohol. It was found that the diameter and surface roughness of individual nickel oxide nanofibers are strongly dependent upon nickel acetate concentration in the precursor. With increasing nickel acetate concentration, the diameter of nanofibers increased and the roughness decreased. An optimum concentration of nickel acetate in the precursor resulted in the formation of smooth and continuous nickel oxide nanofibers whose diameter can be further controlled via electrospinning voltage. Beyond an optimum concentration ofmore » nickel acetate, the resulting nanofibers were found to be ‘flattened’ and ‘wavy’ with occasional cracking across their length. Transmission electron microscopy analysis revealed that the obtained nanofibers are polycrystalline in nature. These nickel oxide nanofibers with varying morphology have potential applications in various engineering domains. - Highlights: • Nickel oxide nanofibers were synthesized via electrospinning. • Fiber diameter and roughness depend on nickel acetate concentration used. • With increasing nickel acetate concentration the roughness of nanofibers decreased. • XRD and TEM revealed a polycrystalline structure of the nanofibers.« less

High-quality fiber fabrication in buffered hydrofluoric acid solution with ultrasonic agitation.

PubMed

Zhong, Nianbing; Liao, Qiang; Zhu, Xun; Wang, Yongzhong; Chen, Rong

2013-03-01

An etching method for preparing high-quality fiber-optic sensors using a buffered etchant with ultrasonic agitation is proposed. The effects of etching conditions on the etch rate and surface morphology of the etched fibers are investigated. The effect of surface roughness is discussed on the fibers' optical properties. Linear etching behavior and a smooth fiber surface can be repeatedly obtained by adjusting the ultrasonic power and etchant pH. The fibers' spectral quality is improved as the ratio of the pit depth to size decreases, and the fibers with smooth surfaces are more sensitive to a bacterial suspension than those with rough surfaces.

Nanotextured PDMS Substrates for Enhanced Roughness and Aptamer Immobilization for Cancer Cell Capture

NASA Astrophysics Data System (ADS)

Islam, Muhymin; Mahmood, Arif; Bellah, Md.; Kim, Young-Tae; Iqbal, Samir

2014-03-01

Detection of circulating tumor cells (CTCs) in the early stages of cancer is requires very sensitive approach. Nanotextured polydimethylsiloxane (PDMS) substrates were fabricated by micro reactive ion etching (Micro-RIE) to have better control on surface morphology and to improve the affinity of PDMS surfaces to capture cancer cells using surface immobilized aptamers. The aptamers were specific to epidermal growth factor receptors (EGFR) present in cell membranes, and overexpressed in tumor cells. We also investigated the effect of nano-scale features on cell capturing by implementing various surfaces of different roughnesses. Three different recipes were used to prepare nanotextured PDMS by micro-RIE using oxygen (O2) and carbon tetrafluoride (CF4). The measured average roughness of three nanotextured PDMS surfaces were found to impact average densities of captured cells. In all cases, nanotextured PDMS facilitated cell capturing possibly due to increased effective surface area of roughened substrates at nanoscale. It was also observed that cell capture efficiency was higher for higher surface roughness. The nanotextured PDMS substrates are thus useful for cancer cytology devices.

Increased endothelial cell adhesion and elongation on micron-patterned nano-rough poly(dimethylsiloxane) films.

PubMed

Ranjan, Ashwini; Webster, Thomas J

2009-07-29

The success of synthetic vascular grafts is largely determined by their ability to promote vital endothelial cell functions such as adhesion, alignment, proliferation, and extracellular matrix (ECM) deposition. Developing such biomaterials requires the design and fabrication of materials that mimic select properties of native extracellular matrices. Furthermore, cells of the native endothelium have elongated and aligned morphology in the direction of blood flow, yet few materials promote this type of morphology initially, but rather rely on blood flow to orient endothelial cells. Therefore, the objective of this in vitro study was to design a biomaterial that mimics the conditions of the micro- and nano-environment of vascular intima tissue suitable for endothelial cell adhesion and elongation to improve the efficacy of small synthetic vascular grafts. Towards this end, patterned poly(dimethylsiloxane) (PDMS) films consisting of periodic arrays of nano-grooves (500 nm), with spacings ranging from 22 to 80 microm, and alternating nano- and micron roughness were fabricated using a novel electron beam physical vapor deposition method followed by polymer casting. By varying pattern spacing, the area of micron- and nano-rough surface was controlled. In vitro rat aortic endothelial cell adhesion and elongation studies indicated that endothelial cell function was enhanced on patterned PDMS surfaces with the widest spacing and greatest surface area of nano-roughness, as compared to more narrow pattern spacings and non-patterned PDMS surfaces. Specifically, endothelial cells adherent on PDMS patterned films of the widest spacing (greatest nano-rough area) displayed almost twice as much elongation as cells on non-patterned surfaces. For these reasons, the present study highlighted design criteria (the use of micron patterns of nano-features on PDMS) that may contribute to the intelligent design of new-generation vascular grafts.

Simulation of RBS spectra with known 3D sample surface roughness

NASA Astrophysics Data System (ADS)

Malinský, Petr; Siegel, Jakub; Hnatowicz, Vladimir; Macková, Anna; Švorčík, Václav

2017-09-01

The Rutherford Backscattering Spectrometry (RBS) is a technique for elemental depth profiling with a nanometer depth resolution. Possible surface roughness of analysed samples can deteriorate the RBS spectra and makes their interpretation more difficult and ambiguous. This work describes the simulation of RBS spectra which takes into account real 3D morphology of the sample surface obtained by AFM method. The RBS spectrum is calculated as a sum of the many particular spectra obtained for randomly chosen particle trajectories over sample 3D landscape. The spectra, simulated for different ion beam incidence angles, are compared to the experimental ones measured with 2.0 MeV 4He+ ions. The main aim of this work is to obtain more definite information on how a particular surface morphology and measuring geometry affects the RBS spectra and derived elemental depth profiles. A reasonable agreement between the measured and simulated spectra was found and the results indicate that the AFM data on the sample surface can be used for the simulation of RBS spectra.

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

NASA Astrophysics Data System (ADS)

Ponchaiya, Pairin; Rattanasakulthong, Watcharee

2017-09-01

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

Modelling of surface roughness effects on impurity erosion and deposition in TEXTOR with a code package SURO/ERO/SDPIC

NASA Astrophysics Data System (ADS)

Dai, Shuyu; Kirschner, A.; Sun, Jizhong; Tskhakaya, D.; Wang, Dezhen

2014-12-01

The roughness-induced uneven erosion-deposition behaviour is widely observed on plasma-wetted surfaces in tokamaks. The three-dimensional (3D) angular distribution of background plasma and impurities is expected to have an impact on the local erosion-deposition characteristic on rough surfaces. The investigations of 13C deposition on rough surfaces in TEXTOR experiments have been re-visited by 3D treatment of surface morphology to evaluate the effect of 3D angular distribution and its connection with surface topography by the code package SURO/ERO/SDPIC. The simulation results show that the erosion/deposition patterns and evolution of surface topography are strongly affected by the azimuthal direction of incident flux. A reduced aspect ratio of rough surface leads to an increase in 13C deposition due to the enhanced trapping ability at surface recessions. The shadowing effect of rough surface has been revealed based on the relationship between 3D incident direction and surface topography properties. The more realistic surface structures used by 3D SURO can well reproduce the experimental results of the increase in the 13C deposition efficiency by a factor of 3-5 on a rough surface compared with a smooth one. The influence of sheath electric field on the local impact angle and resulting 13C deposition has been studied, which indicates that the difference in 13C deposition caused by sheath electric field can be alleviated by the use of more realistic surface structures. The difference in 13C deposition on smooth graphite and tungsten substrates has been specified by consideration of effects of kinetic reflection, enhanced physical sputtering and nucleation.

The influence of surface roughness and high pressure torsion on the growth of anodic titania nanotubes on pure titanium

NASA Astrophysics Data System (ADS)

Hu, Nan; Gao, Nong; Starink, Marco J.

2016-11-01

Anodic titanium dioxide nanotube (TNT) arrays have wide applications in photocatalytic, catalysis, electronics, solar cells and biomedical implants. When TNT coatings are combined with severe plastic deformation (SPD), metal processing techniques which efficiently improve the strength of metals, a new generation of biomedical implant is made possible with both improved bulk and surface properties. This work investigated the effect of processing by high pressure torsion (HPT) and different mechanical preparations on the substrate and subsequently on the morphology of TNT layers. HPT processing was applied to refine the grain size of commercially pure titanium samples and substantially improved their strength and hardness. Subsequent anodization at 30 V in 0.25 wt.% NH4F for 2 h to form TNT layers on sample surfaces prepared with different mechanical preparation methods was carried out. It appeared that the local roughness of the titanium surface on a microscopic level affected the TNT morphology more than the macroscopic surface roughness. For HPT-processed sample, the substrate has to be pre-treated by a mechanical preparation finer than 4000 grit for HPT to have a significant influence on TNTs. During the formation of TNT layers the oxide dissolution rate was increased for the ultrafine-grained microstructure formed due to HPT processing.

Wetting behaviour of carbon nitride nanostructures grown by plasma enhanced chemical vapour deposition technique

NASA Astrophysics Data System (ADS)

Ahmad Kamal, Shafarina Azlinda; Ritikos, Richard; Abdul Rahman, Saadah

2015-02-01

Tuning the wettability of various coating materials by simply controlling the deposition parameters is essential for various specific applications. In this work, carbon nitride (CNx) films were deposited on silicon (1 1 1) substrates using radio-frequency plasma enhanced chemical vapour deposition employing parallel plate electrode configuration. Effects of varying the electrode distance (DE) on the films' structure and bonding properties were investigated using Field emission scanning electron microscopy, Atomic force microscopy, Fourier transform infrared and X-ray photoemission spectroscopy. The wettability of the films was analyzed using water contact angle measurements. At high DE, the CNx films' surface was smooth and uniform. This changed into fibrous nanostructures when DE was decreased. Surface roughness of the films increased with this morphological transformation. Nitrogen incorporation increased with decrease in DE which manifested the increase in both relative intensities of Cdbnd N to Cdbnd C and Nsbnd H to Osbnd H bonds. sp2-C to sp3-C ratio increased as DE decreased due to greater deformation of sp2 bonded carbon at lower DE. The films' characteristics changed from hydrophilic to super-hydrophobic with the decrease in DE. Roughness ratio, surface porosity and surface energy calculated from contact angle measurements were strongly dependent on the morphology, surface roughness and bonding properties of the films.

Effect of two in-office whitening agents on the enamel surface in vivo: a morphological and non-contact profilometric study.

PubMed

Cadenaro, Milena; Breschi, Lorenzo; Nucci, Cesare; Antoniolli, Francesca; Visintini, Erika; Prati, Carlo; Matis, Bruce A; Di Lenarda, Roberto

2008-01-01

This study evaluated the morphological effects produced in vivo by two in-office bleaching agents on enamel surface roughness using a noncontact profilometric analysis of epoxy replicas. The null hypothesis tested was that there would be no difference in the micromorphology of the enamel surface during or after bleaching with two different bleaching agents. Eighteen subjects were selected and randomly assigned to two treatment groups (n=9). The tooth whitening materials tested were 38% hydrogen peroxide (HP) (Opalescence Xtra Boost) and 35% carbamide peroxide (CP) (Rembrandt Quik Start). The bleaching agents were applied in accordance with manufacturer protocols. The treatments were repeated four times at one-week intervals. High precision impressions of the upper right incisor were taken at baseline as the control (CTRL) and after each bleaching treatment (T0: first application, T1: second application at one week, T2: third application at two weeks and T3: fourth application at three weeks). Epoxy resin replicas were poured from impressions, and the surface roughness was analyzed by means of a non-contact profilometer (Talysurf CLI 1000). Epoxy replicas were then observed using SEM. All data were statistically analyzed using ANOVA and differences were determined with a t-test. No significant differences in surface roughness were found on enamel replicas using either 38% hydrogen peroxide or 35% carbamide peroxide in vivo. This in vivo study supports the null hypothesis that two in-office bleaching agents, with either a high concentration of hydrogen or carbamide peroxide, do not alter enamel surface roughness, even after multiple applications.

Optical properties study of silicone polymer PDMS substrate surfaces modified by plasma treatment

NASA Astrophysics Data System (ADS)

Zahid, A.; Dai, B.; Hong, R.; Zhang, D.

2017-10-01

In this study, PDMS (polydimethylsiloxane) substrates with a half-plain, half-rough surface were prepared on a plain and rough fused silica glass substrate using a molding technique. The molded PDMS surface morphology was changed into a half-smooth and half-rough surface after peeling. The modified PDMS surfaces’ optical properties were inspected with and without treatment. The treatment is exposed by oxygen plasma (15 W) for 3 min in a vacuum, down to a pressure of six torr, using a vacuum pump. An atomic force microscope (AMF) and interferometer (white light) indicated that the plasma O2 treatment increased the formation of the plain surface and decreased the formation of the rough surface. The optical properties via a spectrophotometer (lambda) show the resonance from 300 nm to 1200 nm on the rough surface, which is considered to be a faithful reproduction for transmittance and reflectance. The Raman spectra and FDTD simulation results are in excellent agreement; not to be confused with metal local surface plasmon resonances (LSPRs). The Raman spectra peaks and hotspot are the results of the PDMS Si-O backbone. The PDMS substrate presented the diversity of the optical properties, which makes the substrate complementary to various optical applications.

Quantitative assessment of interfacial interactions with rough membrane surface and its implications for membrane selection and fabrication in a MBR.

PubMed

Chen, Jianrong; Mei, Rongwu; Shen, Liguo; Ding, Linxian; He, Yiming; Lin, Hongjun; Hong, Huachang

2015-03-01

The interfacial interactions between a foulant particle and rough membrane surface in a submerged membrane bioreactor (MBR) were quantitatively assessed by using a new-developed method. It was found that the profile of total interaction versus separation distance was complicated. There were an energy barrier and two negative energy ranges in the profile. Further analysis showed that roughness scale significantly affected the strength and properties of interfacial interactions. It was revealed that there existed a critical range of roughness scale within which the total energy in the separation distance ranged from 0 to several nanometers was continually repulsive. Decrease in foulant size would increase the strength of specific interaction energy, but did not change the existence of a critical roughness scale range. These findings suggested the possibility to "tailor" membrane surface morphology for membrane fouling mitigation, and thus gave significant implications for membrane selection and fabrication in MBRs. Copyright © 2014 Elsevier Ltd. All rights reserved.

Quantitative three-dimensional ice roughness from scanning electron microscopy

NASA Astrophysics Data System (ADS)

Butterfield, Nicholas; Rowe, Penny M.; Stewart, Emily; Roesel, David; Neshyba, Steven

2017-03-01

We present a method for inferring surface morphology of ice from scanning electron microscope images. We first develop a novel functional form for the backscattered electron intensity as a function of ice facet orientation; this form is parameterized using smooth ice facets of known orientation. Three-dimensional representations of rough surfaces are retrieved at approximately micrometer resolution using Gauss-Newton inversion within a Bayesian framework. Statistical analysis of the resulting data sets permits characterization of ice surface roughness with a much higher statistical confidence than previously possible. A survey of results in the range -39°C to -29°C shows that characteristics of the roughness (e.g., Weibull parameters) are sensitive not only to the degree of roughening but also to the symmetry of the roughening. These results suggest that roughening characteristics obtained by remote sensing and in situ measurements of atmospheric ice clouds can potentially provide more facet-specific information than has previously been appreciated.

Roughness threshold for cell attachment and proliferation on plasma micro-nanotextured polymeric surfaces: the case of primary human skin fibroblasts and mouse immortalized 3T3 fibroblasts

NASA Astrophysics Data System (ADS)

Bourkoula, A.; Constantoudis, V.; Kontziampasis, D.; Petrou, P. S.; Kakabakos, S. E.; Tserepi, A.; Gogolides, E.

2016-08-01

Poly(methyl methacrylate) surfaces have been micro-nanotextured in oxygen plasmas with increasing ion energy, leading to micro-nanotopography characterized by increased root mean square roughness, correlation length and fractal dimension. Primary human skin fibroblasts and mouse immortalized 3T3 fibroblasts were cultured on these surfaces and the number of adhering cells, their proliferation rate and morphology (cytoplasm and nucleus area) were evaluated as a function of roughness height, correlation length, and fractal dimension. A roughness threshold behavior was observed for both types of cells leading to dramatic cell number decrease above this threshold, which is almost similar for the two types of cells, despite their differences in size and stiffness. The results are discussed based on two theoretical models, which are reconciled and unified when the elastic moduli and the size of the cells are taken into account.

[Observation of topography and analysis of surface contamination of titanium implant after roughness treatment].

PubMed

Cao, Hongdan; Yang, Xiaodong; Wu, Dayi; Zhang, Xingdong

2007-04-01

The roughness treatment of dental implant surface could improve the bone bonding and increase the success rate of implant, but the difference of diverse treatments is still unknown. In this study using scanning electron microscopy (SEM), energy disperse spectrometer (EDS) and the test of contact angle, we studied the microstructure, surface contamination and surface energy, and hence conducted a comparative analysis of the following surface roughness treatments: Polished Treatment (PT), Sandblasting with Alumina(SA), Sandblasting with Aluminia and Acid-etched (SAA), Sandblasting with Titanium Acid-etched (STA), Electro-erosion Treatment(ET). The result of SEM showed that the surface displayed irregularities after roughness treatments and that the surface properties of different roughness treatments had some distinctions. SAA and SA had some sharp edges and protrutions; the STA showed a regular pattern like honeycomb, but the ET sample treated by electric erosion exhibited the deeper pores of different sizes and the pores with a perforated secondary structure. The EDS indicated that the surface was contaminated after the treatment with foreign materials; the SA surface had some embedded contaminations even after acid etching. The measurement of water contact angle indicated that the morphology correlated with the surface treatments. These findings suggest that the distinction of surface structure and composition caused by different treatments may result in the disparity in biological behavior of dental implant.

Meter-scale slopes of candidate MER landing sites from point photoclinometry

USGS Publications Warehouse

Beyer, R.A.; McEwen, A.S.; Kirk, R.L.

2003-01-01

Photoclinometry was used to analyze the small-scale roughness of areas that fall within the proposed Mars Exploration Rover (MER) 2003 landing ellipses. The landing ellipses presented in this study were those in Athabasca Valles, Elysium Planitia, Eos Chasma, Gusev Crater, Isidis Planitia, Melas Chasma, and Meridiani Planum. We were able to constrain surface slopes on length scales comparable to the image resolution (1.5 to 12 m/pixel). The MER 2003 mission has various engineering constraints that each candidate landing ellipse must satisfy. These constraints indicate that the statistical slope values at 5 m baselines are an important criterion. We used our technique to constrain maximum surface slopes across large swaths of each image, and built up slope statistics for the images in each landing ellipse. We are confident that all MER 2003 landing site ellipses in this study, with the exception of the Melas Chasma ellipse, are within the small-scale roughness constraints. Our results have provided input into the landing hazard assessment process. In addition to evaluating the safety of the landing sites, our mapping of small-scale roughnesses can also be used to better define and map morphologic units. The morphology of a surface is characterized by the slope distribution and magnitude of slopes. In looking at how slopes are distributed, we can better define landforms and determine the boundaries of morphologic units. Copyright 2003 by the American Geophysical Union.

Fabricating Superhydrophobic and Superoleophobic Surfaces with Multiscale Roughness Using Airbrush and Electrospray

NASA Astrophysics Data System (ADS)

AL-Milaji, Karam N.

Examples of superhydrophobic surfaces found in nature such as self-cleaning property of lotus leaf and walking on water ability of water strider have led to an extensive investigation in this area over the past few decades. When a water droplet rests on a textured surface, it may either form a liquid-solid-vapor composite interface by which the liquid droplet partially sits on air pockets or it may wet the surface in which the water replaces the trapped air depending on the surface roughness and the surface chemistry. Super water repellent surfaces have numerous applications in our daily life such as drag reduction, anti-icing, anti-fogging, energy conservation, noise reduction, and self-cleaning. In fact, the same concept could be applied in designing and producing surfaces that repel organic contaminations (e.g. low surface tension liquids). However, superoleophobic surfaces are more challenging to fabricate than superhydrophobic surfaces since the combination of multiscale roughness with re-entrant or overhang structure and surface chemistry must be provided. In this study, simple, cost-effective and potentially scalable techniques, i.e., airbrush and electrospray, were employed for the sake of making superhydrophobic and superoleophobic coatings with random and patterned multiscale surface roughness. Different types of silicon dioxide were utilized in this work to in order to study and to characterize the effect of surface morphology and surface roughness on surface wettability. The experimental findings indicated that super liquid repellent surfaces with high apparent contact angles and extremely low sliding angles were successfully fabricated by combining re-entrant structure, multiscale surface roughness, and low surface energy obtained from chemically treating the fabricated surfaces. In addition to that, the experimental observations regarding producing textured surfaces in mask-assisted electrospray were further validated by simulating the actual working conditions and geometries using COMSOL Multiphysics.

Hierarchical roughness of sticky and non-sticky superhydrophobic surfaces

NASA Astrophysics Data System (ADS)

Raza, Muhammad; Kooij, Stefan; van Silfhout, Arend; Zandvliet, Harold; Poelsema, Bene

2011-11-01

The importance of superhydrophobic substrates (contact angle >150° with sliding angle <10°) in modern technology is undeniable. We present a simple colloidal route to manufacture superstructured arrays with single- and multi-length-scaled roughness to obtain sticky and non-sticky superhydrophobic surfaces. The largest length scale is provided by (multi-)layers of silica spheres (1 μm, 500nm and 150nm diameter). Decoration with gold nanoparticles (14nm, 26nm and 47nm) gives rise to a second length scale. To lower the surface energy, gold nanoparticles are functionalized with dodecanethiol and the silica spheres by perfluorooctyltriethoxysilane. The morphology was examined by helium ion microscopy (HIM), while wettability measurements were performed by using the sessile drop method. We conclude that wettability can be controlled by changing the surface chemistry and/or length scales of the structures. To achieve truly non-sticky superhydrophobic surfaces, hierarchical roughness plays a vital role.

Slope-velocity equilibrium and evolution of surface roughness on a stony hillslope

NASA Astrophysics Data System (ADS)

Nearing, Mark A.; Polyakov, Viktor O.; Nichols, Mary H.; Hernandez, Mariano; Li, Li; Zhao, Ying; Armendariz, Gerardo

2017-06-01

Slope-velocity equilibrium is hypothesized as a state that evolves naturally over time due to the interaction between overland flow and surface morphology, wherein steeper areas develop a relative increase in physical and hydraulic roughness such that flow velocity is a unique function of overland flow rate independent of slope gradient. This study tests this hypothesis under controlled conditions. Artificial rainfall was applied to 2 m by 6 m plots at 5, 12, and 20 % slope gradients. A series of simulations were made with two replications for each treatment with measurements of runoff rate, velocity, rock cover, and surface roughness. Velocities measured at the end of each experiment were a unique function of discharge rates, independent of slope gradient or rainfall intensity. Physical surface roughness was greater at steeper slopes. The data clearly showed that there was no unique hydraulic coefficient for a given slope, surface condition, or rainfall rate, with hydraulic roughness greater at steeper slopes and lower intensities. This study supports the hypothesis of slope-velocity equilibrium, implying that use of hydraulic equations, such as Chezy and Manning, in hillslope-scale runoff models is problematic because the coefficients vary with both slope and rainfall intensity.

Potential biomedical applications of ion beam technology

NASA Technical Reports Server (NTRS)

Banks, B. A.; Weigand, A. J.; Babbush, C. A.; Vankampen, C. L.

1976-01-01

Electron bombardment ion thrusters used as ion sources have demonstrated a unique capability to vary the surface morphology of surgical implant materials. The microscopically rough surface texture produced by ion beam sputtering of these materials may result in improvements in the biological response and/or performance of implanted devices. Control of surface roughness may result in improved attachment of the implant to soft tissue, hard tissue, bone cement, or components deposited from blood. Potential biomedical applications of ion beam texturing discussed include: vascular prostheses, artificial heart pump diaphragms, pacemaker fixation, percutaneous connectors, orthopedic pros-thesis fixtion, and dental implants.

Potential biomedical applications of ion beam technology

NASA Technical Reports Server (NTRS)

Banks, B. A.; Weigand, A. J.; Van Kampen, C. L.; Babbush, C. A.

1976-01-01

Electron bombardment ion thrusters used as ion sources have demonstrated a unique capability to vary the surface morphology of surgical implant materials. The microscopically rough surface texture produced by ion beam sputtering of these materials may result in improvements in the biological response and/or performance of implanted devices. Control of surface roughness may result in improved attachment of the implant to soft tissue, hard tissue, bone cement, or components deposited from blood. Potential biomedical applications of ion beam texturing discussed include: vascular prostheses, artificial heart pump diaphragms, pacemaker fixation, percutaneous connectors, orthopedic prosthesis fixation, and dental implants.

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.

A phase field crystal model simulation of morphology evolution and misfit dislocation generation in nanoheteroepitaxy

NASA Astrophysics Data System (ADS)

Zhang, J.; Chen, Z.; Cheng, C.; Wang, Y. X.

2017-10-01

A phase field crystal (PFC) model is employed to study morphology evolution of nanoheteroepitaxy and misfit dislocation generation when applied with enhanced supercooling, lattice mismatch and substrate vicinal angle conditions. Misfit strain that rises due to lattice mismatch causes rough surfaces or misfit dislocations, deteriorates film properties, hence, efforts taken to reveal their microscopic mechanism are significant for film quality improvement. Uniform islands, instead of misfit dislocations, are developed in subcritical thickness film, serving as a way of strain relief by surface mechanism. Misfit dislocations generate when strain relief by surface mechanism is deficient in higher supercooling, multilayers of misfit dislocations dominate, but the number of layers reduces gradually when the supercooling is further enhanced. Rough surfaces like islands or cuspate pits are developed which is ascribed to lattice mismatch, multilayers of misfit dislocations generate to further enhance lattice mismatch. Layers of misfit dislocations generate at a thickening position at enhanced substrate vicinal angle, this further enhancing the angle leading to sporadic generation of misfit dislocations.

AFM surface imaging of AISI D2 tool steel machined by the EDM process

NASA Astrophysics Data System (ADS)

Guu, Y. H.

2005-04-01

The surface morphology, surface roughness and micro-crack of AISI D2 tool steel machined by the electrical discharge machining (EDM) process were analyzed by means of the atomic force microscopy (AFM) technique. Experimental results indicate that the surface texture after EDM is determined by the discharge energy during processing. An excellent machined finish can be obtained by setting the machine parameters at a low pulse energy. The surface roughness and the depth of the micro-cracks were proportional to the power input. Furthermore, the AFM application yielded information about the depth of the micro-cracks is particularly important in the post treatment of AISI D2 tool steel machined by EDM.

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

NASA Astrophysics Data System (ADS)

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

2018-04-01

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

Morphological classification and microanalysis of tire tread particles worn by abrasion or corrosion

NASA Astrophysics Data System (ADS)

Crosta, Giovanni F.

2011-06-01

Two types of tread wear particles are investigated: tread wear particles from a steel brush abrader (TrBP) and particles produced during a steering pad run (TrSP). A leaching experiment in water at pH = 7.5 for 24 and 48h was carried out on TrBP to simulate environmental degradation. Images of all materials were collected by a scanning electron microscope (SEM) together with element microanalytical (EDX) data. Surface morphology is described by a function of wave number (the "enhanced spectrum") obtained from SEM image analysis and non-linear filtering. A surface roughness index, ρ, is derived from the enhanced spectrum. The innovative contribution of this work is the representation of morphology by means of ρ, which, together with EDX data, allows the quantitative characterization of the materials. In particular, the surface roughness of leached TrBP is shown to decay in time and is related to the corresponding microanalytical data for the first time. The morphology of steering pad TrSP, affected by included mineral particles, is shown to be more heterogeneous. Differences in morphology (enhanced spectra and ρ), elemental composition and surface chemistry of TrBP and TrSP are discussed. All methods described and implemented herewith can be immediately applied to other types of tread wear material. The arguments put forward herewith should help in the proper design of those experiments aimed at assessing the impact of tread wear materials on the environment and on human health.

Re-analysis of previous laboratory phase curves: 1. Variations of the opposition effect morphology with the textural properties, and an application to planetary surfaces

NASA Astrophysics Data System (ADS)

Déau, Estelle; Flandes, Alberto; Spilker, Linda J.; Petazzoni, Jérôme

2013-11-01

Typical variations in the opposition effect morphology of laboratory samples at optical wavelengths are investigated to probe the role of the textural properties of the surface (roughness, porosity and grain size). A previously published dataset of 34 laboratory phase curves is re-analyzed and fit with several morphological models. The retrieved morphological parameters that characterize the opposition surge, amplitude, width and slope (A, HWHM and S respectively) are correlated to the single scattering albedo, the roughness, the porosity and the grain size of the samples. To test the universality of the laboratory samples’ trends, we use previously published phase curves of planetary surfaces, including the Moon, satellites and rings of the giant planets. The morphological parameters of the surge (A and HWHM) for planetary surfaces are found to have a non-monotonic variation with the single scattering albedo, similar to that observed in asteroids (Belskaya, I.N., Shevchenko, V.G. [2000]. Icarus 147, 94-105), which is unexplained so far. The morphological parameters of the surge (A and HWHM) for laboratory samples seem to exhibit the same non-monotonic variation with single scattering albedo. While the non-monotonic variation with albedo was already observed by Nelson et al. (Nelson, R.M., Hapke, B.W., Smythe, W.D., Hale, A.S., Piatek, J.L. [2004]. Planetary regolith microstructure: An unexpected opposition effect result. In: Mackwell, S., Stansbery, E. (Eds.), Proc. Lunar Sci. Conf. 35, p. 1089), we report here the same variation for the angular width.

Electro and Magneto-Electropolished Surface Micro-Patterning on Binary and Ternary Nitinol

PubMed Central

Munroe, Norman; McGoron, Anthony

2012-01-01

In this study, an Atomic Force Microscopy (AFM) roughness analysis was performed on non-commercial Nitinol alloys with Electropolished (EP) and Magneto-Electropolished (MEP) surface treatments and commercially available stents by measuring Root-Mean-Square (RMS), Average Roughness (Ra), and Surface Area (SA) values at various dimensional areas on the alloy surfaces, ranging from (800 × 800 nm) to (115 × 115μm), and (800 × 800 nm) to (40 × 40 μm) on the commercial stents. Results showed that NiTi-Ta 10 wt% with an EP surface treatment yielded the highest overall roughness, while the NiTi-Cu 10 wt% alloy had the lowest roughness when analyzed over (115 × 115 μm). Scanning Electron Microscopy (SEM) and Energy Dispersive Spectroscopy (EDS) analysis revealed unique surface morphologies for surface treated alloys, as well as an aggregation of ternary elements Cr and Cu at grain boundaries in MEP and EP surface treated alloys, and non-surface treated alloys. Such surface micro-patterning on ternary Nitinol alloys could increase cellular adhesion and accelerate surface endothelialization of endovascular stents, thus reducing the likelihood of in-stent restenosis and provide insight into hemodynamic flow regimes and the corrosion behavior of an implantable device influenced from such surface micro-patterns. PMID:22754200

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.

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

PubMed

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

2011-01-01

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

Morphological properties of collagen fibers in porcine lamina propria

PubMed Central

Johanes, Iecun; Mihelc, Elaine; Sivasankar, Mahalakshmi; Ivanisevic, Albena

2009-01-01

Objectives Collagen influences the biomechanical properties of vocal folds. Altered collagen morphology has been implicated in dysphonia associated with aging and scarring. Documenting the morphological properties of native collagen in healthy vocal folds is essential to understand the structural and functional alterations to collagen with aging and disease. Our primary objective was to quantify the morphological properties of collagen in the vocal fold lamina propria. Our secondary exploratory objective was to investigate the effects of pepsin exposure on the morphological properties of collagen in the lamina propria. Design Experimental, in vitro study with porcine model. Methods Lamina propria was dissected from 26 vocal folds and imaged with Atomic Force Microscopy (AFM). Morphological data on d-periodicity, diameter, and roughness of collagen fibers were obtained. To investigate the effects of pepsin exposure on collagen morphology, vocal fold surface was exposed to pepsin or sham challenge prior to lamina propria dissection and AFM imaging. Results The d-periodicity, diameter, and roughness values for native vocal fold collagen are consistent with literature reports for collagen fibers in other body tissue. Pepsin exposure on vocal fold surface did not appear to change the morphological properties of collagen fibers in the lamina propria. Conclusions Quantitative data on collagen morphology were obtained at nanoscale resolution. Documenting collagen morphology in healthy vocal folds is critical for understanding the physiological changes to collagen with aging and scarring, and for designing biomaterials that match the native topography of lamina propria. PMID:20171830

[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.

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

PubMed Central

Mishra, Mitul Kumar; Prakash, Shobha

2013-01-01

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

Osteoblast response to magnesium ion-incorporated nanoporous titanium oxide surfaces.

PubMed

Park, Jin-Woo; Kim, Youn-Jeong; Jang, Je-Hee; Song, Hwangjun

2010-11-01

This study investigated the surface characteristics and in vitro osteoconductivity of a titanium (Ti) surface incorporated with the magnesium ions (Mg) produced by hydrothermal treatment for future application as an endosseous implant surface. Mg-incorporated Ti oxide surfaces were produced by hydrothermal treatment using Mg-containing solution on two different microstructured surfaces--abraded minimally rough (Ma) or grit-blasted moderately rough (RBM) samples. The surface characteristics were evaluated using scanning electron microscopy, thin-film X-ray diffractometry, X-ray photoelectron spectroscopy, optical profilometry, and inductively coupled plasma atomic emission spectroscopy (ICP-AES). MC3T3-E1 pre-osteoblast cell attachment, proliferation, alkaline phosphatase (ALP) activity, and quantitative analysis of osteoblastic gene expression on Ma, RBM, Mg-incorporated Ma (Mg), and Mg-incorporated grit-blasted (RBM/Mg) Ti surfaces were evaluated. Hydrothermal treatment produced an Mg-incorporated Ti oxide layer with nanoporous surface structures. Mg-incorporated surfaces showed surface morphologies and surface roughness values almost identical to those of untreated smooth or micro-rough surfaces at the micron scale. ICP-AES analysis showed Mg ions released from treated surfaces into the solution. Mg incorporation significantly increased cellular attachment (P=0 at 0.5 h, P=0.01 at 1 h) on smooth surfaces, but no differences were found on micro-rough surfaces. Mg incorporation further increased ALP activity in cells grown on both smooth and micro-rough surfaces at 7 and 14 days of culture (P=0). Real-time polymerase chain reaction analysis showed higher mRNA expressions of the osteoblast transcription factor gene (Dlx5), various integrins, and the osteoblast phenotype genes (ALP, bone sialoprotein and osteocalcin) in cells grown on micro-rough (RBM) and Mg-incorporated (Mg and RBM/Mg) surfaces than those on Ma surfaces. Mg incorporation further increased the mRNA expressions of key osteoblast genes and integrins (α1, α2, α5, and β1) in cells grown on both the smooth and the micro-rough surfaces. These results indicate that an Mg-incorporated nanoporous Ti oxide surface produced by hydrothermal treatment may improve implant bone healing by enhancing the attachment and differentiation of osteoblastic cells. © 2010 John Wiley & Sons A/S.

Effect of plasma treatment (He/CH4) on glass surface for the reduction of powder flux adhesion in the spray drying process

NASA Astrophysics Data System (ADS)

Ramlan, Nadiah; Zamri, Nazirah Wahidah Mohd; Maskat, Mohd Yusof; Hoong, Chin Oi; Theng, Lau Yen; Zubairi, Saiful Irwan

2018-04-01

A 50Hz glow discharge He/CH4 plasma was generated and applied for the modification of glass surface to reduce powder adhesion on the wall of spray dryer. The hydrophobicity of the glass samples determined by the water droplet contact angle and adhesion weight on glass, dependent on the CH4 flow rate and plasma exposure time. There was a peak that appeared at 1470 cm-1 on the surface of treated glass indicating the presence of CH3 groups from ATR-FTIR data. Surface morphology analysis using scanning electron microscopy (SEM) showed changes of roughness in the surface-treated glass. The presence of alkyl group (CH3) that deposited on the glass surface is one of the factors that contribute to the increase in the surface roughness. The surface roughness will reflect the value of contact angle where hydrophobic surface are rougher compared to hydrophilic surface. The plasma treatment could enhance the value of the contact angle and thus reduced the adhesion on the spray dryer glass surface.

Dependence of the surface roughness of MAPLE-deposited films on the solvent parameters

NASA Astrophysics Data System (ADS)

Caricato, A. P.; Leggieri, G.; Martino, M.; Vantaggiato, A.; Valerini, D.; Cretì, A.; Lomascolo, M.; Manera, M. G.; Rella, R.; Anni, M.

2010-12-01

Matrix-assisted pulsed laser evaporation (MAPLE) was used to deposit layers of poly(9,9-dioctylfluorene) (PFO) to study the relation between the solvent properties (laser light absorption, boiling temperature and solubility parameters) and the morphology of the deposited films. To this end, the polymer was diluted (0.5 wt%) in tetrahydrofuran—THF, toluene and toluene/hexane mixtures. The thickness of the films was equal to 70±20 nm. The morphology and uniformity of the films was investigated by Atomic Force Microscopy and by the photoluminescence emission properties of the polymer films, respectively. It is shown that, although the solubility parameters of the solvents are important in controlling the film roughness and morphology, the optical absorption properties and boiling temperature play a very important role, too. In fact, for matrices characterized by the same total solubility parameter, lower roughness values are obtained for films prepared using solvents with lower penetration depth of the laser radiation and higher boiling temperatures.

Tailoring the morphology of raspberry-like carbon black/polystyrene composite microspheres for fabricating superhydrophobic surface

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

Bao, Yubin; Li, Qiuying, E-mail: liqy@ecust.edu.cn; Shanghai Key Laboratory Polymeric Materials

In our previous report, raspberry-like carbon black/polystyrene (CB/PS) composite microsphere was prepared through heterocoagulation process. Based on the previous study, in the present work, the morphology of raspberry-like CB/PS particle is tailored through adjusting the polarity and the concentration ratio of CB/PS colloidal suspension with the purpose to prepare particulate film for the fabrication of superhydrophobic surface. Scanning electron microscope (SEM) confirms the morphology of raspberry-like particle and the coverage of CB. Rough surfaces fabricated by raspberry-like particles with proper morphology are observed by SEM and clear evidence of superhydrophobic surface is shown. The structure of raspberry-like particle is analyzedmore » by atom force microscope. The proposed relationship between the hydrophobicity and the structure of CB aggregates on the surface of PS microsphere is discussed in details.« less

The coevolution of bed roughness, grain clustering, surface armoring, hydraulic roughness, and sediment transport rate in experimental coarse alluvial channels: implications for long-term effects of gravel augmentation

NASA Astrophysics Data System (ADS)

Johnson, J. P.; Aronovitz, A. C.

2012-12-01

We conducted laboratory flume experiments to quantify changes in multiple factors leading to mountain river bed stability (i.e., minimal bed changes in space and time), and to understand how stable beds respond to perturbations in sediment supply. Experiments were run in a small flume 4 m long by 0.1 m wide. We imposed an initial well-graded size distribution of sediment (from coarse sand to up to 4 cm clasts), a steady water discharge (0.9 L/s), and initial bed surface slopes (8% and 12%). We measured outlet sediment flux and size distribution, bed topography and surface size distributions, and water depths; from these we calculated total shear stress, form drag and skin friction stress partitioning, and hydraulic roughness. The bed was initially allowed to stabilize with no imposed upstream sediment flux. This stabilization occurred due to significant changes in all of the factors listed in the title, and resulted in incipient step-pool like bed morphologies. In addition, this study was designed to explore possible long-term effects of gravel augmentation on mountain channel morphology and surface grain size. While the short-term goal of gravel augmentation is usually to cause fining of surface sediment patches, we find that the long-term effects may be opposite. We perturbed the stabilized channels by temporarily imposing an upstream sediment flux of the finest sediment size fraction (sand to granules). Median surface sizes initially decreased due to fine sediment deposition, although transport rates of intermediate-sized grains increased. When the fine sediment supply was stopped, beds evolved to be both rougher and coarser than they had been previously, because the largest grains remained on the bed but intermediate-sized grains were preferentially transported out, leaving higher fractions of larger grains on the surface. Existing models for mixed grain size transport actually predict changes in mobilization reasonably well, but do not explicity account for surface roughness evolution. Our results indicate a nonlinear relationship between surface median grain size and bed roughness.

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

NASA Astrophysics Data System (ADS)

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

2012-09-01

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

Early osteoblast responses to orthopedic implants: Synergy of surface roughness and chemistry of bioactive ceramic coating.

PubMed

Aniket; Reid, Robert; Hall, Benika; Marriott, Ian; El-Ghannam, Ahmed

2015-06-01

Pro-osteogenic stimulation of bone cells by bioactive ceramic-coated orthopedic implants is influenced by both surface roughness and material chemistry; however, their concomitant impact on osteoblast behavior is not well understood. The aim of this study is to investigate the effects of nano-scale roughness and chemistry of bioactive silica-calcium phosphate nanocomposite (SCPC50) coated Ti-6Al-4V on modulating early bone cell responses. Cell attachment was higher on SCPC50-coated substrates compared to the uncoated controls; however, cells on the uncoated substrate exhibited greater spreading and superior quality of F-actin filaments than cells on the SCPC50-coated substrates. The poor F-actin filament organization on SCPC50-coated substrates is thought to be due to the enhanced calcium uptake by the ceramic surface. Dissolution analyses showed that an increase in surface roughness was accompanied by increased calcium uptake, and increased phosphorous and silicon release, all of which appear to interfere with F-actin assembly and osteoblast morphology. Moreover, cell attachment onto the SCPC50-coated substrates correlated with the known adsorption of fibronectin, and was independent of surface roughness. High-throughput genome sequencing showed enhanced expression of extracellular matrix and cell differentiation related genes. These results demonstrate a synergistic relationship between bioactive ceramic coating roughness and material chemistry resulting in a phenotype that leads to early osteoblast differentiation. © 2014 Wiley Periodicals, Inc.

Atomic force microscopic study of the effects of ethanol on yeast cell surface morphology.

PubMed

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

2006-02-01

The detrimental effects of ethanol toxicity on the cell surface morphology of Saccharomyces cerevisiae (strain NCYC 1681) and Schizosaccharomyces pombe (strain DVPB 1354) were investigated using an atomic force microscope (AFM). In combination with culture viability and mean cell volume measurements AFM studies allowed us to relate the cell surface morphological changes, observed on nanometer lateral resolution, with the cellular stress physiology. Exposing yeasts to increasing stressful concentrations of ethanol led to decreased cell viabilities and mean cell volumes. Together with the roughness and bearing volume analyses of the AFM images, the results provided novel insight into the relative ethanol tolerance of S. cerevisiae and Sc. pombe.

Hierarchical roughness of sticky and non-sticky superhydrophobic surfaces

NASA Astrophysics Data System (ADS)

Raza, Muhammad Akram; Kooij, Stefan; van Silfhout, Arend; Zandvliet, Harold; Poelsema, Bene; Physics Of Interfaces; Nanomaterials Team

2011-03-01

The importance of superhydrophobic substrates (contact angle > 150 r withslidingangle 10 r) inmoderntechnologyisundeniable . Wepresentasimplecolloidalroutetomanufacturesuperstructuredarrayswithsingle - andmulti - length - scaledroughnesstoobtainstickyandnon - stickysuperhydrophobicsurfaces . Thelargestlengthscaleisprovidedby (multi -) layersofsilicaspheres (1 μ m, 500nm and 150nm diameter). Decoration with gold nanoparticles (14nm, 26nm and 47nm) gives rise to a second length scale. To lower the surface energy, gold nanoparticles are functionalized with dodecanethiol and the silica spheres by perfluorooctyltriethoxysilane. The morphology was examined by helium ion microscopy (HIM), while wettability measurements were performed by using the sessile drop method. We conclude that wettability can be controlled by changing the surface chemistry and/or length scales of the structures. To achieve truly non-sticky superhydrophobic surfaces, hierarchical roughness plays a vital role.

Electrodeposition of gold thin films with controlled morphologies and their applications in electrocatalysis and SERS.

PubMed

Elias, Jamil; Gizowska, Magdalena; Brodard, Pierre; Widmer, Roland; Dehazan, Yoram; Graule, Thomas; Michler, Johann; Philippe, Laetitia

2012-06-29

Here, an easy and effective electrochemical route towards the synthesis of gold thin films with well-controlled roughness, morphology and crystallographic orientation is reported. To control these different factors, the applied potential during deposition played a major role. A tentative nucleation and growth mechanism is demonstrated by means of electrochemical characterizations and a formation mechanism is proposed. Interestingly, the differences in geometry and orientation of the different gold deposits have shown a clear correlation with the electrocatalytical activity in the case of oxygen sensing. In addition, not only the electrocatalytical activity but also the surface-enhanced Raman scattering of the gold deposits have been found to depend both on the roughness and on the size of the surface nanostructures, allowing a fine tuning by controlling these two parameters during deposition.

Electrodeposition of gold thin films with controlled morphologies and their applications in electrocatalysis and SERS

NASA Astrophysics Data System (ADS)

Elias, Jamil; Gizowska, Magdalena; Brodard, Pierre; Widmer, Roland; deHazan, Yoram; Graule, Thomas; Michler, Johann; Philippe, Laetitia

2012-06-01

Here, an easy and effective electrochemical route towards the synthesis of gold thin films with well-controlled roughness, morphology and crystallographic orientation is reported. To control these different factors, the applied potential during deposition played a major role. A tentative nucleation and growth mechanism is demonstrated by means of electrochemical characterizations and a formation mechanism is proposed. Interestingly, the differences in geometry and orientation of the different gold deposits have shown a clear correlation with the electrocatalytical activity in the case of oxygen sensing. In addition, not only the electrocatalytical activity but also the surface-enhanced Raman scattering of the gold deposits have been found to depend both on the roughness and on the size of the surface nanostructures, allowing a fine tuning by controlling these two parameters during deposition.

Quantitative analysis of surface characteristics and morphology in Death Valley, California using AIRSAR data

NASA Technical Reports Server (NTRS)

Kierein-Young, K. S.; Kruse, F. A.; Lefkoff, A. B.

1992-01-01

The Jet Propulsion Laboratory Airborne Synthetic Aperture Radar (JPL-AIRSAR) is used to collect full polarimetric measurements at P-, L-, and C-bands. These data are analyzed using the radar analysis and visualization environment (RAVEN). The AIRSAR data are calibrated using in-scene corner reflectors to allow for quantitative analysis of the radar backscatter. RAVEN is used to extract surface characteristics. Inversion models are used to calculate quantitative surface roughness values and fractal dimensions. These values are used to generate synthetic surface plots that represent the small-scale surface structure of areas in Death Valley. These procedures are applied to a playa, smooth salt-pan, and alluvial fan surfaces in Death Valley. Field measurements of surface roughness are used to verify the accuracy.

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

PubMed

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

2018-07-01

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

Effect of Electropulsing-Assisted Ultrasonic Nanocrystalline Surface Modification on the Surface Mechanical Properties and Microstructure of Ti-6Al-4V Alloy

NASA Astrophysics Data System (ADS)

Ye, Yongda; Wang, Haibo; Tang, Guoyi; Song, Guolin

2018-05-01

The effect of electropulsing-assisted ultrasonic nanocrystalline surface modification (EP-UNSM) on surface mechanical properties and microstructure of Ti-6Al-4V alloy is investigated. Compared to conventional ultrasonic nanocrystalline surface modification (UNSM), EP-UNSM can effectively facilitate surface roughness and morphology, leading to excellent surface roughness (reduced from Ra 0.918 to Ra 0.028 μm by UNSM and Ra 0.019 μm by EP-UNSM) and smoother morphology with less cracks and defects. Surface friction coefficients are enhanced, resulting in lower and smoother friction coefficients. In addition, the surface-strengthened layer and ultra-refined grains are significantly enhanced with more severe plastic deformation and a greater surface hardness (a maximum hardness value of 407 HV and an effective depth of 550 μm, in comparison with the maximum hardness value of 364 HV and effective depth of 300 μm obtained by conventional UNSM). Remarkable enhancement of surface mechanical properties can be attributed to the refined gradient microstructure and the enhanced severe plastic deformation layer induced by coupling the effects of UNSM and electropulsing. The accelerated dislocation mobility and atom diffusion caused by the thermal and athermal effects of electropulsing treatment may be the primary intrinsic reasons for these improvements.

Atomic force microscopy studies of homoepitaxial GaN layers grown on GaN template by laser MBE

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

Choudhary, B. S.; Rajasthan Technical University, Rawatbhata Road, Kota 324010; Singh, A.

We have grown homoepitaxial GaN films on metal organic chemical vapor deposition (MOCVD) grown 3.5 µm thick GaN on sapphire (0001) substrate (GaN template) using an ultra-high vacuum (UHV) laser assisted molecular beam epitaxy (LMBE) system. The GaN films were grown by laser ablating a polycrystalline solid GaN target in the presence of active r.f. nitrogen plasma. The influence of laser repetition rates (10-30 Hz) on the surface morphology of homoepitaxial GaN layers have been studied using atomic force microscopy. It was found that GaN layer grown at 10 Hz shows a smooth surface with uniform grain size compared to the rough surfacemore » with irregular shape grains obtained at 30 Hz. The variation of surface roughness of the homoepitaxial GaN layer with and without wet chemical etching has been also studied and it was observed that the roughness of the film decreased after wet etching due to the curved structure/rough surface.« less

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

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

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

Effect of heat treatment of wood on the morphology, surface roughness and penetration of simulated and human blood.

PubMed

Rekola, J; Lassila, L V J; Nganga, S; Ylä-Soininmäki, A; Fleming, G J P; Grenman, R; Aho, A J; Vallittu, P K

2014-01-01

Wood has been used as a model material for the development of novel fiber-reinforced composite bone substitute biomaterials. In previous studies heat treatment of wood was perceived to significantly increase the osteoconductivity of implanted wood material. The objective of this study was to examine some of the changing attributes of wood materials that may contribute to improved biological responses gained with heat treatment. Untreated and 140°C and 200°C heat-treated downy birch (Betula pubescens Ehrh.) were used as the wood materials. Surface roughness and the effect of pre-measurement grinding were measured with contact and non-contact profilometry. Liquid interaction was assessed with a dipping test using two manufactured liquids (simulated blood) as well as human blood. SEM was used to visualize possible heat treatment-induced changes in the hierarchical structure of wood. The surface roughness was observed to significantly decrease with heat treatment. Grinding methods had more influence on the surface contour and roughness than heat treatment. The penetration of the human blood in the 200°C heat-treated exceeded that in the untreated and 140°C heat-treated materials. SEM showed no significant change due to heat treatment in the dry-state morphology of the wood. The results of the liquid penetration test support previous findings in literature concerning the effects of heat treatment on the biological response to implanted wood. Heat-treatment has only a marginal effect on the surface contour of wood. The highly specialized liquid conveyance system of wood may serve as a biomimetic model for the further development of tailored fiber-composite materials.

In vitro mesenchymal stem cell responses on laser-welded NiTi alloy.

PubMed

Chan, C W; Hussain, I; Waugh, D G; Lawrence, J; Man, H C

2013-04-01

The biocompatibility of NiTi after laser welding was studied by examining the in vitro (mesenchymal stem cell) MSC responses at different sets of time varying from early (4 to 12h) to intermediate phases (1 and 4 days) of cell culture. The effects of physical (surface roughness and topography) and chemical (surface Ti/Ni ratio) changes as a consequence of laser welding in different regions (WZ, HAZ, and BM) on the cell morphology and cell coverage were studied. The results in this research indicated that the morphology of MSCs was affected primarily by the topographical factors in the WZ: the well-defined and directional dendritic pattern and the presence of deeper grooves. The morphology of MSCs was not significantly modulated by surface roughness. Despite the possible initial Ni release in the medium during the cell culture, no toxic effect seemed to cause to MSCs as evidenced by the success of adhesion and spreading of the cells onto different regions in the laser weldment. The good biocompatibility of the NiTi laser weldment has been firstly reported in this study. Copyright © 2012 Elsevier B.V. All rights reserved.

Effect of nano-scale morphology on micro-channel wall surface and electrical characterization in lead silicate glass micro-channel plate

NASA Astrophysics Data System (ADS)

Cai, Hua; Li, Fangjun; Xu, Yanglei; Bo, Tiezhu; Zhou, Dongzhan; Lian, Jiao; Li, Qing; Cao, Zhenbo; Xu, Tao; Wang, Caili; Liu, Hui; Li, Guoen; Jia, Jinsheng

2017-10-01

Micro-channel plate (MCP) is a two dimensional arrays of microscopic channel charge particle multiplier. Silicate composition and hydrogen reduction are keys to determine surface morphology of micro-channel wall in MCP. In this paper, lead silicate glass micro-channel plates in two different cesium contents (0at%, 0.5at%) and two different hydrogen reduction temperatures (400°C,450°C) were present. The nano-scale morphology, elements content and chemical states of microporous wall surface treated under different alkaline compositions and reduction conditions was investigated by Atomic Force Microscopy (AFM) and X-ray Photoelectron Spectroscopy (XPS), respectively. Meanwhile, the electrical characterizations of MCP, including the bulk resistance, electron gain and the density of dark current, were measured in a Vacuum Photoelectron Imaging Test Facility (VPIT).The results indicated that the granular phase occurred on the surface of microporous wall and diffuses in bulk glass is an aggregate of Pb atom derived from the reduction of Pb2+. In micro-channel plate, the electron gain and bulk resistance were mainly correlated to particle size and distribution, the density of dark current (DDC) went up with the increasing root-mean-square roughness (RMS) on the microporous wall surface. Adding cesiums improved the size of Pb atomic aggregation, lowered the relative concentration of [Pb] reduced from Pb2+ and decreased the total roughness of micro-channel wall surface, leading a higher bulk resistance, a lower electron gain and a less dark current. Increasing hydrogen reduction temperature also improved the size of Pb atomic aggregation, but enhanced the relative concentration of [Pb] and enlarged the total roughness of micro-channel wall surface, leading a higher bulk resistance, a lower electron gain and a larger dark current. The reasons for the difference of electrical characteristics were discussed.

Effect of hydrodynamics and surface roughness on the electrochemical behaviour of carbon steel in CSG produced water

NASA Astrophysics Data System (ADS)

Eyu, Gaius Debi; Will, Geoffrey; Dekkers, Willem; MacLeod, Jennifer

2015-12-01

The influence of fluid flow, surface roughness and immersion time on the electrochemical behaviour of carbon steel in coal seam gas produced water under static and hydrodynamic conditions has been studied. The disc electrode surface morphology before and after the corrosion test was characterized using scanning electron microscopy (SEM). The corrosion product was examined using X-ray photoelectron spectroscopy (XPS) and X-ray diffractometry (XRD).The results show that the anodic current density increased with increasing surface roughness and consequently a decrease in corrosion surface resistance. Under dynamic flow conditions, the corrosion rate increased with increasing rotating speed due to the high mass transfer coefficient and formation of non-protective akaganeite β-FeO(OH) and goethite α-FeO(OH) corrosion scale at the electrode surface. The corrosion rate was lowest at 0 rpm. The corrosion rate decreased in both static and dynamic conditions with increasing immersion time. The decrease in corrosion rate is attributed to the deposition of corrosion products on the electrode surface. SEM results revealed that the rougher surface exhibited a great tendency toward pitting corrosion.

Structural properties 3,16-bis triisopropylsilylethynyl (pentacene) (TIPS-pentacene) thin films onto organic dielectric layer using slide coating method

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

Rusnan, Fara Naila; Mohamad, Khairul Anuar; Seria, Dzul Fahmi Mohd Husin

3,16-bis triisopropylsilylethynyl (Pentacene) (TIPS-Pentacene) compactable interface property is important in order to have a good arrangement of molecular structure. Comparison for TIPS-Pentacene deposited between two different surface layers conducted. 0.1wt% TIPS-Pentacene diluted in chloroform were deposited onto poly(methylmeaclyrate) (PMMA) layered transparent substrates using slide coating method. X-ray diffraction (XRD) used to determine crystallinity of thin films. Series of (00l) diffraction peaks obtained with sharp first peaks (001) for TIPS-Pentacene deposited onto PMMA layer at 5.35° and separation of 16.3 Å. Morphology and surface roughness were carried out using scanning electron microscope (SEM) and surface profilemeter LS500, respectively.TIPS-Pentacene deposited onto PMMAmore » layer formed needled-like-shape grains with 10.26 nm surface roughness. These properties were related as thin film formed and its surface roughness plays important role towards good mobility devices.« less

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.

Study of the Effect of Nanoparticles and Surface Morphology on Reverse Osmosis and Nanofiltration Membrane Productivity

PubMed Central

Fang, Yuming; Duranceau, Steven J.

2013-01-01

To evaluate the significance of reverse osmosis (RO) and nanofiltration (NF) surface morphology on membrane performance, productivity experiments were conducted using flat-sheet membranes and three different nanoparticles, which included SiO2, TiO2 and CeO2. In this study, the productivity rate was markedly influenced by membrane surface morphology. Atomic force microscopy (AFM) analysis of membrane surfaces revealed that the higher productivity decline rates associated with polyamide RO membranes as compared to that of a cellulose acetate NF membrane was due to the inherent ridge-and-valley morphology of the active layer. The unique polyamide active layer morphology was directly related to the surface roughness, and was found to contribute to particle accumulation in the valleys causing a higher flux decline than in smoother membranes. Extended RO productivity experiments using laboratory grade water and diluted pretreated seawater were conducted to compare the effect that different nanoparticles had on membrane active layers. Membrane flux decline was not affected by particle type when the feed water was laboratory grade water. On the other hand, membrane productivity was affected by particle type when pretreated diluted seawater served as feed water. It was found that CeO2 addition resulted in the least observable flux decline, followed by SiO2 and TiO2. A productivity simulation was conducted by fitting the monitored flux data into a cake growth rate model, where the model was modified using a finite difference method to incorporate surface thickness variation into the analysis. The ratio of cake growth term (k1) and particle back diffusion term (k2) was compared in between different RO and NF membranes. Results indicated that k2 was less significant for surfaces that exhibited a higher roughness. It was concluded that the valley areas of thin-film membrane surfaces have the ability to capture particles, limiting particle back diffusion. PMID:24956946

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.

The effects of tungsten's pre-irradiation surface condition on helium-irradiated morphology

DOE PAGES

Garrison, Lauren M.; Kulcinski, Gerald L.

2015-07-17

Erosion is a concern associated with the use of tungsten as a plasma-facing component in fusion reactors. To compare the damage progression, polycrystalline tungsten (PCW) and (110) single crystal tungsten (SCW) samples were prepared with (1) a mechanical polish (MP) with roughness values in the range of 0.018–0.020 μm and (2) an MP and electropolish (MPEP) resulting in roughness values of 0.010–0.020 μm for PCW and 0.003–0.005 μm for SCW samples. Samples were irradiated with 30 keV He + at 1173 K to fluences between 3 × 10 21 and 6 × 10 22 He/m 2. The morphologies that developedmore » after low-fluence bombardment were different for each type of sample—MP SCW, MPEP SCW, MP PCW, and MPEP PCW. At the highest fluence, the SCW MPEP sample lost significantly more mass and developed a different morphology than the MP SCW sample. The PCW samples developed a similar morphology and had similar mass loss at the highest fluence. Surface preparation can have a significant effect on post-irradiation morphology that should be considered for the design of future fusion reactors such as ITER and DEMO.« less

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

NASA Astrophysics Data System (ADS)

Ruan, Dajiang

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

Morphologic Quality of DSMs Based on Optical and Radar Space Imagery

NASA Astrophysics Data System (ADS)

Sefercik, U. G.; Bayik, C.; Karakis, S.; Jacobsen, K.

2011-09-01

Digital Surface Models (DSMs) are representing the visible surface of the earth by the height corresponding to its X-, Y-location and height value Z. The quality of a DSM can be described by the accuracy and the morphologic details. Both depend upon the used input information, the used technique and the roughness of the terrain. The influence of the topographic details to the DSM quality is shown for the test fields Istanbul and Zonguldak. Zonguldak has a rough mountainous character with heights from sea level up to 1640m, while Istanbul is dominated by rolling hills going up to an elevation of 435m. DSMs from SPOT-5, the SRTM C-band height models and ASTER GDEM have been investigated. The DSMs have been verified with height models from large scale aerial photos being more accurate and including morphologic details. It was necessary to determine and respect shifts of the height models caused by datum problems and orientation of the height models. The DSM quality is analyzed depending upon the terrain inclination. The DSM quality differs for both test fields. The morphologic quality depends upon the point spacing of the analyzed DSMs and the terrain characteristics.

In Vitro Assessment of Early Bacterial Activity on Micro/Nanostructured Ti6Al4V Surfaces.

PubMed

Valdez-Salas, Benjamin; Beltrán-Partida, Ernesto; Castillo-Uribe, Sandra; Curiel-Álvarez, Mario; Zlatev, Roumen; Stoytcheva, Margarita; Montero-Alpírez, Gisela; Vargas-Osuna, Lidia

2017-05-18

It is imperative to understand and systematically compare the initial interactions between bacteria genre and surface properties. Thus, we fabricated a flat, anodized with 80 nm TiO₂ nanotubes (NTs), and a rough Ti6Al4V surface. The materials were characterized using field-emission scanning electron microscopy (FE-SEM), energy dispersive X-ray spectroscopy (EDX) and atomic force microscopy (AFM). We cultured in vitro Staphylococcus epidermidis ( S. epidermidis ) and Pseudomonas aeruginosa ( P. aeruginosa ) to evaluate the bacterial-surface behavior by FE-SEM and viability calculation. In addition, the initial effects of human osteoblasts were tested on the materials. Gram-negative bacteria showed promoted adherence and viability over the flat and rough surface, while NTs displayed opposite activity with altered morphology. Gram-positive bacteria illustrated similar cellular architecture over the surfaces but with promoted surface adhesion bonds on the flat alloy. Rough surfaces supported S. epidermidis viability, whilst NTs exhibited lower vitality. NTs advocated promoted better osteoblast organization with enhanced vitality. Gram-positive bacteria suggested preferred adhesion capability over flat and carbon-rich surfaces. Gram-negative bacteria were strongly disturbed by NTs but largely stimulated by flat and rough materials. Our work proposed that the chemical profile of the material surface and the bacterial cell wall characteristics might play an important role in the bacteria-surface interactions.

Silica nano-particle super-hydrophobic surfaces: the effects of surface morphology and trapped air pockets on hydrodynamic drainage forces.

PubMed

Chan, Derek Y C; Uddin, Md Hemayet; Cho, Kwun L; Liaw, Irving I; Lamb, Robert N; Stevens, Geoffrey W; Grieser, Franz; Dagastine, Raymond R

2009-01-01

We used atomic force microscopy to study dynamic forces between a rigid silica sphere (radius approximately 45 microm) and a silica nano-particle super-hydrophobic surface (SNP-SHS) in aqueous electrolyte, in the presence and absence of surfactant. Characterization of the SNP-SHS surface in air showed a surface roughness of up to two microns. When in contact with an aqueous phase, the SNP-SHS traps large, soft and stable air pockets in the surface interstices. The inherent roughness of the SNP-SHS together with the trapped air pockets are responsible for the superior hydrophobic properties of SNP-SHS such as high equilibrium contact angle (> 140 degrees) of water sessile drops on these surfaces and low hydrodynamic friction as observed in force measurements. We also observed that added surfactants adsorbed at the surface of air pockets magnified hydrodynamic interactions involving the SNP-SHS. The dynamic forces between the same silica sphere and a laterally smooth mica surface showed that the fitted Navier slip lengths using the Reynolds lubrication model were an order of magnitude larger than the length scale of the sphere surface roughness. The surface roughness and the lateral heterogeneity of the SNP-SHS hindered attempts to characterize the dynamic response using the Reynolds lubrication model even when augmented with a Navier slip boundary.

Investigation of the surface morphology of biocompatible chitosan-based hydrogels and xerogels

NASA Astrophysics Data System (ADS)

Zhuravleva, Yulia Yu.; Malinkina, Olga N.; Shipovskaya, Anna B.

2018-04-01

Our biocompatible hydrogel systems obtained by the sol-gel technqiue and based on chitosan and silicon polyolates are promising for medical and biological applications. The surface microrelief of these sol-gel materials (hydrogels and xerogels) based on chitosan and silicon tetraglycerolate was explored by AFM and SEM. A significant influence of the component ratio in the mixed system on the morphology and surface profile of the hydrogels and xerogels prepared therefrom was established. An increased content of the structure-forming component (chitosan) in the system was shown to increase the roughness scale of the hydrogel surface and to promote the porosity of the xerogel structure.

Effect of nanocomposite gate-dielectric properties on pentacene microstructure and field-effect transistor characteristics.

PubMed

Lee, Wen-Hsi; Wang, Chun-Chieh

2010-02-01

In this study, the effect of surface energy and roughness of the nanocomposite gate dielectric on pentacene morphology and electrical properties of pentacene OTFT are reported. Nanoparticles TiO2 were added in the polyimide matrix to form a nanocomposite which has a significantly different surface characteristic from polyimide, leading to a discrepancy in the structural properties of pentacene growth. A growth mode of pentacene deposited on the nanocomposite is proposed to explain successfully the effect of surface properties of nanocomposite gate dielectric such as surface energy and roughness on the pentacene morphology and electrical properties of OTFT. To obtain the lower surface energy and smoother surface of nanocomposite gate dielectric that is responsible for the desired crystalline, microstructure of pentacene and electrical properties of device, a bottom contact OTFT-pentacene deposited on the double-layer nanocomposite gate dielectric consisting of top smoothing layer of the neat polyimide and bottom layer of (PI+ nano-TiO2 particles) nanocomposite has been successfully demonstrated to exhibit very promising performance including high current on to off ratio of about 6 x 10(5), threshold voltage of -10 V and moderately high filed mobility of 0.15 cm2V(-1)s(-1).

Selective modulation of cell response on engineered fractal silicon substrates

PubMed Central

Gentile, Francesco; Medda, Rebecca; Cheng, Ling; Battista, Edmondo; Scopelliti, Pasquale E.; Milani, Paolo; Cavalcanti-Adam, Elisabetta A.; Decuzzi, Paolo

2013-01-01

A plethora of work has been dedicated to the analysis of cell behavior on substrates with ordered topographical features. However, the natural cell microenvironment is characterized by biomechanical cues organized over multiple scales. Here, randomly rough, self-affinefractal surfaces are generated out of silicon,where roughness Ra and fractal dimension Df are independently controlled. The proliferation rates, the formation of adhesion structures, and the morphology of 3T3 murine fibroblasts are monitored over six different substrates. The proliferation rate is maximized on surfaces with moderate roughness (Ra ~ 40 nm) and large fractal dimension (Df ~ 2.4); whereas adhesion structures are wider and more stable on substrates with higher roughness (Ra ~ 50 nm) and lower fractal dimension (Df ~ 2.2). Higher proliferation occurson substrates exhibiting densely packed and sharp peaks, whereas more regular ridges favor adhesion. These results suggest that randomly roughtopographies can selectively modulate cell behavior. PMID:23492898

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

Qiusheng, Y., E-mail: qsyan@gdut.edu.cn; Senkai, C., E-mail: senkite@sina.com; Jisheng, P., E-mail: panjisheng@gdut.edu.cn

Different machining processes were used in the single crystal SiC wafer machining. SEM was used to observe the surface morphology and a cross-sectional cleavages microscopy method was used for subsurface cracks detection. Surface and subsurface cracks characteristics of single crystal SiC wafer in abrasive machining were analysed. The results show that the surface and subsurface cracks system of single crystal SiC wafer in abrasive machining including radial crack, lateral crack and the median crack. In lapping process, material removal is dominated by brittle removal. Lots of chipping pits were found on the lapping surface. With the particle size becomes smaller,more » the surface roughness and subsurface crack depth decreases. When the particle size was changed to 1.5µm, the surface roughness Ra was reduced to 24.0nm and the maximum subsurface crack was 1.2µm. The efficiency of grinding is higher than lapping. Plastic removal can be achieved by changing the process parameters. Material removal was mostly in brittle fracture when grinding with 325# diamond wheel. Plow scratches and chipping pits were found on the ground surface. The surface roughness Ra was 17.7nm and maximum subsurface crack depth was 5.8 µm. When grinding with 8000# diamond wheel, the material removal was in plastic flow. Plastic scratches were found on the surface. A smooth surface of roughness Ra 2.5nm without any subsurface cracks was obtained. Atomic scale removal was possible in cluster magnetorheological finishing with diamond abrasive size of 0.5 µm. A super smooth surface eventually obtained with a roughness of Ra 0.4nm without any subsurface crack.« less

Statistical characterization of surface features from tungsten-coated divertor inserts in the DIII-D Metal Rings Campaign

NASA Astrophysics Data System (ADS)

Adams, Jacob; Unterberg, Ezekial; Chrobak, Christopher; Stahl, Brian; Abrams, Tyler

2017-10-01

Continuing analysis of tungsten-coated inserts from the recent DIII-D Metal Rings Campaign utilizes a statistical approach to study carbon migration and deposition on W surfaces and to characterize the pre- versus post-exposure surface morphology. A TZM base was coated with W using both CVD and PVD and allowed for comparison between the two coating methods. The W inserts were positioned in the lower DIII-D divertor in both the upper (shelf) region and lower (floor) region and subjected to multiple plasma shots, primarily in H-mode. Currently, the post-exposure W inserts are being characterized using SEM/EDX to qualify the surface morphology and to quantify the surface chemical composition. In addition, profilometry is being used to measure the surface roughness of the inserts both before and after plasma exposure. Preliminary results suggest a correlation between the pre-exposure surface roughness and the level of carbon deposited on the surface. Furthermore, ongoing in-depth analysis may reveal insights into the formation mechanism of nanoscale bumps found in the carbon-rich regions of the W surfaces that have not yet been explained. Work supported in part by US DoE under the Science Undergraduate Laboratory Internship (SULI) program and under DE-FC02-04ER54698.

Nano-scale topography of bearing surface in advanced alumina/zirconia hip joint before and after severe exposure in water vapor environment.

PubMed

Pezzotti, Giuseppe; Saito, Takuma; Padeletti, Giuseppina; Cossari, Pierluigi; Yamamoto, Kengo

2010-06-01

The aim of this study was to perform a surface morphology assessment with nanometer scale resolution on femoral heads made of an advanced zirconia toughened alumina (ZTA) composite. Femoral heads were characterized to a degree of statistical accuracy in the as-received state and after exposures up to 100 h in severe vapor-moist environment. Surface screening was made using an atomic force microscope (AFM). Scanning was systematically repeated on portions of surface as large as several tens of micrometers, randomly selected on the head surface, to achieve sufficient statistical reliability without lowering the nanometer-scale spatial resolution of the roughness measurement. No significant difference was found in the recorded values of surface roughness after environmental exposure (at 134 degrees C, under 2 bar), which was always comparable to that of the as-received head. Surface roughness safely lay <10 nm after environmental exposures up to 100 h, which corresponded to an exposure time in vivo of several human lifetimes (i.e., according to an experimentally derived thermal activation energy). In addition, the roughness results were significantly (about one order of magnitude) lower as compared to those recorded on femoral heads made of monolithic zirconia tested under the same conditions. (c) 2010 Orthopaedic Research Society. Published by Wiley Periodicals, Inc.

DOE Award No. FG02-93ER14331 Final Technical Report

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

Bartynski, Robert

We have studyed new aspects of the relationships between nanoscale surface features and heterogeneous catalysis or electrocatalysis. We concentrate on atomically rough and morphologically unstable surfaces of catalytic metal single crystals (Re, Ru, Ir) that undergo nanoscale faceting when interacting with strongly adsorbed species (e.g. O, N, C) at elevated temperatures.

Mineral loss and morphological changes in dental enamel induced by a 16% carbamide peroxide bleaching gel.

PubMed

Soares, Diana Gabriela; Ribeiro, Ana Paula Dias; Sacono, Nancy Tomoko; Loguércio, Alessandro Dourado; Hebling, Josimeri; Costa, Carlos Alberto de Souza

2013-01-01

The aim of this study was to compare the effect of a 16% carbamide peroxide (CP) gel and a 10% CP gel on mineralized enamel content and morphology. Enamel blocks from bovine incisors were subjected to a 14-day treatment (8 h/day) with 10% or 16% CP gels. Knoop microhardness was evaluated before bleaching and at 1, 7 or 14 days after this treatment (50 g/15 s). Mineral content (energy-dispersive x-ray spectroscopy), surface roughness and topography (atomic force microscopy) were evaluated at the 14-day period. Data were analyzed statistically by two-way ANOVA and Tukey's test (α=0.05). Significant microhardness reduction was observed at the 7 th and 14 th days for 10% CP gel, and for all bleaching times for 16% CP gel (p<0.05). At the 14-day period, a significant decrease in Ca and P content, increase on surface roughness (p<0.05) as well as on picks and valleys distance were observed when both bleaching gels were used. These enamel alterations were more intense for 16% CP gel. It was concluded that both CP-based gels promoted loss of mineral structure from enamel, resulting in a rough and porous surface. However, 16% CP gel caused the most intense adverse effects on enamel.

Significantly improved surface morphology of N-polar GaN film grown on SiC substrate by the optimization of V/III ratio

NASA Astrophysics Data System (ADS)

Deng, Gaoqiang; Zhang, Yuantao; Yu, Ye; Yan, Long; Li, Pengchong; Han, Xu; Chen, Liang; Zhao, Degang; Du, Guotong

2018-04-01

In this paper, N-polar GaN films with different V/III ratios were grown on vicinal C-face SiC substrates by metalorganic chemical vapor deposition. During the growth of N-polar GaN film, the V/III ratio was controlled by adjusting the molar flow rate of ammonia while keeping the trimethylgallium flow rate unchanged. The influence of the V/III ratio on the surface morphology of N-polar GaN film has been studied. We find that the surface root mean square roughness of N-polar GaN film over an area of 20 × 20 μm2 can be reduced from 8.13 to 2.78 nm by optimization of the V/III ratio. Then, using the same growth conditions, N-polar InGaN/GaN multiple quantum wells (MQWs) light-emitting diodes (LEDs) were grown on the rough and the smooth N-polar GaN templates, respectively. Compared with the LED grown on the rough N-polar GaN template, dramatically improved interface sharpness and luminescence uniformity of the InGaN/GaN MQWs are achieved for the LED grown on the smooth N-polar GaN template.

Maintaining the pluripotency of mouse embryonic stem cells on gold nanoparticle layers with nanoscale but not microscale surface roughness

NASA Astrophysics Data System (ADS)

Lyu, Zhonglin; Wang, Hongwei; Wang, Yanyun; Ding, Kaiguo; Liu, Huan; Yuan, Lin; Shi, Xiujuan; Wang, Mengmeng; Wang, Yanwei; Chen, Hong

2014-05-01

Efficient control of the self-renewal and pluripotency maintenance of embryonic stem cell (ESC) is a prerequisite for translating stem cell technologies to clinical applications. Surface topography is one of the most important factors that regulates cell behaviors. In the present study, micro/nano topographical structures composed of a gold nanoparticle layer (GNPL) with nano-, sub-micro-, and microscale surface roughnesses were used to study the roles of these structures in regulating the behaviors of mouse ESCs (mESCs) under feeder-free conditions. The distinctive results from Oct-4 immunofluorescence staining and quantitative real-time polymerase chain reaction (qPCR) demonstrate that nanoscale and low sub-microscale surface roughnesses (Rq less than 392 nm) are conducive to the long-term maintenance of mESC pluripotency, while high sub-microscale and microscale surface roughnesses (Rq greater than 573 nm) result in a significant loss of mESC pluripotency and a faster undirectional differentiation, particularly in long-term culture. Moreover, the likely signalling cascades engaged in the topological sensing of mESCs were investigated and their role in affecting the maintenance of the long-term cell pluripotency was discussed by analyzing the expression of proteins related to E-cadherin mediated cell-cell adhesions and integrin-mediated focal adhesions (FAs). Additionally, the conclusions from MTT, cell morphology staining and alkaline phosphatase (ALP) activity assays show that the surface roughness can provide a potent regulatory signal for various mESC behaviors, including cell attachment, proliferation and osteoinduction.Efficient control of the self-renewal and pluripotency maintenance of embryonic stem cell (ESC) is a prerequisite for translating stem cell technologies to clinical applications. Surface topography is one of the most important factors that regulates cell behaviors. In the present study, micro/nano topographical structures composed of a gold nanoparticle layer (GNPL) with nano-, sub-micro-, and microscale surface roughnesses were used to study the roles of these structures in regulating the behaviors of mouse ESCs (mESCs) under feeder-free conditions. The distinctive results from Oct-4 immunofluorescence staining and quantitative real-time polymerase chain reaction (qPCR) demonstrate that nanoscale and low sub-microscale surface roughnesses (Rq less than 392 nm) are conducive to the long-term maintenance of mESC pluripotency, while high sub-microscale and microscale surface roughnesses (Rq greater than 573 nm) result in a significant loss of mESC pluripotency and a faster undirectional differentiation, particularly in long-term culture. Moreover, the likely signalling cascades engaged in the topological sensing of mESCs were investigated and their role in affecting the maintenance of the long-term cell pluripotency was discussed by analyzing the expression of proteins related to E-cadherin mediated cell-cell adhesions and integrin-mediated focal adhesions (FAs). Additionally, the conclusions from MTT, cell morphology staining and alkaline phosphatase (ALP) activity assays show that the surface roughness can provide a potent regulatory signal for various mESC behaviors, including cell attachment, proliferation and osteoinduction. Electronic supplementary information (ESI) available. See DOI: 10.1039/c4nr01540a

Electrospun TiO₂ nanofibers decorated Ti substrate for biomedical application.

PubMed

Dumitriu, Cristina; Stoian, Andrei Bogdan; Titorencu, Irina; Pruna, Vasile; Jinga, Victor V; Latonen, Rose-Marie; Bobacka, Johan; Demetrescu, Ioana

2014-12-01

Various TiO2 nanofibers on Ti surface have been fabricated via electrospinning and calcination. Due to different elaboration conditions the electrospun fibers have different surface feature morphologies, characterized by scanning electronic microscopy, surface roughness, and contact angle measurements. The results have indicated that the average sample diameters are between 32 and 44 nm, roughness between 61 and 416 nm, and all samples are hydrophilic. As biological evaluation, cell culture with MG63 cell line originally derived from a human osteosarcoma was performed and correlation between nanofibers elaboration, properties and cell response was established. The cell adherence and growth are more evident on Ti samples with more aligned fibers, higher roughness and strong hydrophilic character and such fibers have been elaborated with a high speed rotating cylinder collector, confirming the idea that nanostructure elaboration conditions guide the cells' growth. Copyright © 2014 Elsevier B.V. All rights reserved.

Microtopographic evolution of lava flows at Cima volcanic field, Mojave Desert, California

NASA Technical Reports Server (NTRS)

Farr, Tom G.

1992-01-01

Microtopographic profiles were measured and power spectra calculated for dated lava flow surfaces at Cima volcanic field in the eastern Mojave Desert of California in order to quantify changes in centimeter- to meter-scale roughness as a function of age. For lava flows younger than about 0.8 m.y., roughness over all spatial scales decreases with age, with meter-scale roughness decreasing slightly more than centimeter scales. Flows older than about 0.8 m.y. show a reversal of this trend, becoming as rough as young flows at these scales. Modeling indicates that eolian deposition can explain most of the change observed in the offset, or roughness amplitude, of power spectra of flow surface profiles up to 0.8 m.y. Other processes, such as rubbing and stone pavement development, appear to have a minor effect in this age range. Changes in power spectra of surfaces older than about 0.8 m.y. are consistent with roughening due to fluvial dissection. These results agree qualitatively with a process-response model that attributes systematic changes in flow surface morphology to cyclic changes in the rates of eolian, soil formation, and fluvial processes. Identification of active surficial processes and estimation of the extent of their effects, or stage of surficial evolution, through measurement of surface roughness will help put the correlation of surficial units on a quantitative basis. This may form the basis for the use of radar remote sensing data to help in regional correlations of surficial units.

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

NASA Astrophysics Data System (ADS)

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

2017-12-01

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

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

NASA Astrophysics Data System (ADS)

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

2018-03-01

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

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.

[Effect of hydrofluoric acid concentration on the surface morphology and bonding effectiveness of lithium disilicate glass ceramics to resin composites].

PubMed

Hailan, Qian; Lingyan, Ren; Rongrong, Nie; Xiangfeng, Meng

2017-12-01

This study aimed at determining the influence of hydrofluoric acid (HF) in varied concentrations on the surface morphology of lithium disilicate glass ceramics and bond durability between resin composites and post-treated lithium disilicate glass ceramics. After being sintered, ground, and washed, 72 as-prepared specimens of lithium disilicate glass ceramics with dimensions of 11 mm×13 mm×2 mm were randomly divided into three groups. Each group was treated with acid solution [32% phosphoric acid (PA) or 4% or 9.5% HF] for 20 s. Then, four acidified specimens from each group were randomly selected. One of the specimens was used to observe the surface morphology using scanning electron microscopy, and the others were used to observe the surface roughness using a surface roughness meter (including Ra, Rz, and Rmax). After treatment with different acid solutions in each group, 20 samples were further treated with silane coupling agent/resin adhesive/resin cement (Monobond S/Multilink Primer A&B/Multilink N), followed by bonding to a composite resin column (Filtek™ Z350) with a diameter of 3 mm. A total of 20 specimens in each group were randomly divided into two subgroups, which were used for measuring the microshear bond strength, with one of them subjected to cool-thermal cycle for 20 000 times. The surface roughness (Ra, Rz, and Rmax) of lithium disilicate glass ceramics treated with 4% or 9.5% HF was significantly higher than that of the ceramic treated with PA (P<0.05). The lithium disilicate glass ceramics treated with 9.5% HF also demonstrated better surface roughness (Rz and Rmax) than that of the ceramics treated with 4% HF. Cool-thermal cycle treatment reduced the bond strength of lithium disilicate glass ceramics in all groups (P<0.05). After cool-thermal cycle, the lithium disilicate glass ceramics treated with HF had higher bond strength than that of the ceramics treated with PA. The lithium disilicate glass ceramics treated with 4% HF had higher bond strength than that of the ceramics treated with 9.5% HF (P<0.05). During cool-thermal cycle, the lithium disilicate glass ceramics treated with 4% HF demonstrated higher reduction in bond strength than that of the samples treated with 9.5% HF (P<0.05). The concentration of HF significantly affected the surface morphology of lithium disilicate glass ceramics and the bond durability between resin composites and post-treated lithium disilicate glass ceramics. The bond strength between resin composites and post-treated lithium disilicate glass ceramic was more efficiently maintained by treatment with 9.5% HF.

Surface and subsurface cracks characteristics of single crystal SiC wafer in surface machining

NASA Astrophysics Data System (ADS)

Qiusheng, Y.; Senkai, C.; Jisheng, P.

2015-03-01

Different machining processes were used in the single crystal SiC wafer machining. SEM was used to observe the surface morphology and a cross-sectional cleavages microscopy method was used for subsurface cracks detection. Surface and subsurface cracks characteristics of single crystal SiC wafer in abrasive machining were analysed. The results show that the surface and subsurface cracks system of single crystal SiC wafer in abrasive machining including radial crack, lateral crack and the median crack. In lapping process, material removal is dominated by brittle removal. Lots of chipping pits were found on the lapping surface. With the particle size becomes smaller, the surface roughness and subsurface crack depth decreases. When the particle size was changed to 1.5µm, the surface roughness Ra was reduced to 24.0nm and the maximum subsurface crack was 1.2µm. The efficiency of grinding is higher than lapping. Plastic removal can be achieved by changing the process parameters. Material removal was mostly in brittle fracture when grinding with 325# diamond wheel. Plow scratches and chipping pits were found on the ground surface. The surface roughness Ra was 17.7nm and maximum subsurface crack depth was 5.8 µm. When grinding with 8000# diamond wheel, the material removal was in plastic flow. Plastic scratches were found on the surface. A smooth surface of roughness Ra 2.5nm without any subsurface cracks was obtained. Atomic scale removal was possible in cluster magnetorheological finishing with diamond abrasive size of 0.5 µm. A super smooth surface eventually obtained with a roughness of Ra 0.4nm without any subsurface crack.

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.

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

NASA Astrophysics Data System (ADS)

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

2009-08-01

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

Effect of Er:YAG laser irradiation on bonding property of zirconia ceramics to resin cement.

PubMed

Lin, Yihua; Song, Xiaomeng; Chen, Yaming; Zhu, Qingping; Zhang, Wei

2013-12-01

This study aimed to investigate whether or not an erbium: yttrium-aluminum-garnet (Er:YAG) laser could improve the bonding property of zirconia ceramics to resin cement. Surface treatments can improve the bonding properties of dental ceramics. However, little is known about the effect of Er:YAG laser irradiated on zirconia ceramics. Specimens of zirconia ceramic pieces were made, and randomly divided into 11 groups according to surface treatments, including one control group (no treatment), one air abrasion group, and nine Er:YAG laser groups. The laser groups were subdivided by applying different energy intensities (100, 200, or 300 mJ) and irradiation times (5, 10, or 15 sec). After surface treatments, ceramic pieces had their surface morphology observed, and their surface roughness was measured. All specimens were bonded to resin cement. Shear bond strength was measured after the bonded specimens were stored in water for 24 h, and additionally aged by thermocycling. Statistical analyses were performed using one way analysis of variance (ANOVA) and Tukey's test for shear bond strength, and Dunnett's t test for surface roughness, with α=0.05. Er:YAG laser irradiation changed the morphological characteristics of zirconia ceramics. Higher energy intensities (200, 300 mJ) could roughen the ceramics, but also caused surface cracks. There were no significant differences in the bond strength between the control group and the laser groups treated with different energy intensities or irradiation times. Air abrasion with alumina particles induced highest surface roughness and shear bond strength. Er:YAG laser irradiation cannot improve the bonding property of zirconia ceramics to resin cement. Enhancing irradiation intensities and extending irradiation time have no benefit on the bond of the ceramics, and might cause material defect.

[The effects of surface morphology of calcium phosphate ceramics on apatite formation in dynamic SBF].

PubMed

Duan, Yourong; Lü, Wanxin; Wang, Chaoyuan; Chen, Jiyong; Zhang, Xingdong

2002-06-01

Bone-like apatite formation on the surface of calcium phosphate ceramics has been believed to be the prerequisite of new bone growth on ceramics and to be related to the osteoinductivity of the material. The research of the factors effecting bone-like apatite formation is a great help in understanding the mechanism of osteoinduction. This paper is aimed to a comparative study of in vitro formation of bone-like apatite on the surface of dense and rough calcium phosphate ceramics with SBF flowing at different rates. The results showed that the rough surface was beneficial to the formation of bone-like apatite, and the apatite formed faster in 1.5 SBF than in SBF. Rough surface, namely, larger surface area, increased the dissolution of Ca2+ and HPO4(2-) and higher concentration of Ca2+ and HPO4(2-) ions of SBF and was in turn advantageous to the accumulation of Ca2+, HPO4(2-), PO4(3-) near the ceramic surface. Local supersaturating concentration of Ca2+, HPO4(2-), PO4(3-) near sample surface was essential to nucleation of apatite on the surface of sample.

Evaluation of Mechanical Properties of Glass Fiber Posts Subjected to Laser Surface Treatments.

PubMed

Barbosa Siqueira, Carolina; Spadini de Faria, Natália; Raucci-Neto, Walter; Colucci, Vivian; Alves Gomes, Erica

2016-10-01

The aim of this study was to evaluate the influence of laser irradiation on flexural strength, elastic modulus, and surface roughness and morphology of glass fiber posts (GFPs). Laser treatment of GFPs has been introduced to improve its adhesion properties. A total of 40 GFPs were divided into 4 groups according to the irradiation protocol: GC-no irradiation, GYAG-irradiation with erbium:yttrium-aluminum-garnet [Er:YAG], GCR-irradiation with erbium, chromium:yttrium-scandium-gallium-garnet (Er,Cr:YSGG), and GDI-irradiation with diode laser. The GFP roughness and morphology were evaluated through laser confocal microscopy before and after surface treatment. Three-point bending flexural test measured flexural strength and elastic modulus. Data about elastic modulus and flexural strength were subjected to one-way ANOVA and Bonferroni test (p < 0.05). The effect of roughness was evaluated using the linear mixed effects model and Bonferroni test (p < 0.05). Laser treatment changed surface roughness in the groups GCR (p = 0.000) and GDI (p = 0.007). The mean flexural strength in GYAG (995.22 MPa) was similar to that in GC (980.48 MPa) (p = 1.000) but different from that in GCR (746.83 MPa) and that in GDI (691.34 MPa) (p = 0.000). No difference was found between the groups GCR and GDI (p = 0.86). For elastic modulus: GYAG (24.47 GPa) was similar to GC (25.92 GPa) (p = 1.000) but different from GCR (19.88 GPa) (p = 0.002) and GDI (17.20 GPa) (p = 0.000). The different types of lasers, especially Er,Cr:YSGG and 980 ηm diode, influenced the mechanical properties of GFPs.

Development of Biomimetic and Functionally Responsive Surfaces

NASA Astrophysics Data System (ADS)

Anastasiadis, Spiros H.

2010-03-01

Controlling the surface morphology of solids and manufacturing of functional surfaces with special responsive properties has been the subject of intense research. We report a methodology for creating multifunctionally responsive surfaces by irradiating silicon wafers with femtosecond laser pulses and subsequently coating them with different types of functional conformal coatings. Such surfaces exhibit controlled dual-scale roughness at the micro- and the nano-scale, which mimics the hierarchical morphology of water repellent natural surfaces. When a simple alkylsilane coating is utilized, highly water repellent surfaces are produced that quantitatively compare to those of the Lotus leaf. When a polymer brush is ``grafted from" these surfaces based on a pH-sensitive polymer, the surfaces can alter their behavior from super-hydrophilic (after immersion in a low pH buffer) to super-hydrophobic and water-repellent (following immersion to a high pH buffer). We quantify the water repellency of such responsive systems by drop elasticity measurements whereas we demonstrate that the water repellent state of such surface requires appropriate hydrophobicity of the functionalizing polymer. When a photo-responsive azobenzene-type polymer is deposited, a dynamic optical control of the wetting properties is obtained and the surface can be switched from super-hydrophilic (following UV irradiation) to hydrophobic (following green irradiation). In all the above cases we show that the principal effect of roughness is to cause amplification of the response to the different external stimuli.

Surface Morphology of Undoped and Doped ZnSe Films

NASA Technical Reports Server (NTRS)

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

1998-01-01

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

Effects of Bleaching Agents Combined with Regular and Whitening Toothpastes on Surface Roughness and Mineral Content of Enamel.

PubMed

Attia, Mariana Lerner; Cavalli, Vanessa; do Espírito Santo, Ana Maria; Martin, Airton Abrahão; D'Arce, Maria Beatriz Freitas; Aguiar, Flávio Henrique Baggio; Lovadino, José Roberto; do Rego, Marcos Augusto; Cavalcanti, Andréa Nóbrega; Liporoni, Priscila Christiane Suzy

2015-07-01

The purpose of this study was to evaluate surface roughness and changes in the composition of enamel submitted to different bleaching protocols and toothbrushing with regular and whitening toothpastes. Bleaching treatment could promote morphological and chemical changes in enamel surface. Enamel blocks were randomized into nine groups (n=10) according to the bleaching treatment (no bleaching, control group; 6% hydrogen peroxide, HP; or 10% carbamide peroxide, CP) and toothpaste used (placebo, PL; regular, R; or whitening dentifrice, W). Bleaching was performed according to manufacturers' instructions and all groups were submitted to 30,000 cycles of simulated toothbrushing with toothpaste (PL, R, or W). Mineral content evaluation and enamel roughness were evaluated initially (T1), after bleaching (T2), and after toothbrushing (T3), using an energy-dispersive micro X-ray fluorescence spectrometer and profilometry, respectively. Data were statistically analyzed with two way ANOVA, Tukey, and Dunnett tests (5%). Enamel surface roughness was influenced by bleaching and toothbrushing. Surface roughness increased for the groups that brushed with the placebo dentifrice (CP+PL, HP+PL, C+PL) and for the control group that brushed with whitening dentifrice (C+W). Enamel Ca/P ratio decreased after bleaching, but toothbrushing, regardless of the dentifrice used, did not reduce the enamel mineral content. The bleaching treatment resulted in a decrease of enamel mineral content, but the studied dentifrices did not contribute to surface mineral loss.

Investigations on the effects of mouthrinses on the colour stability and surface roughness of different dental bioceramics

PubMed Central

Varol, Osman

2017-01-01

PURPOSE In this study, three bioceramic materials, [IPS Empress CAD (Ivoclar), IPS e.max CAD (Ivoclar), and Lava Ultimate CAD (3M ESPE)] were treated with three commercial mouthrinses [Listerine, Tantum Verde, and Klorhex]; and changes in colour reflectance and surface roughness values were then quantitatively assessed. MATERIALS AND METHODS One hundred and twenty ceramic samples, with dimensions of 2 × 12 × 14 mm, were prepared and divided into nine sample groups, except three control samples. The samples were immersed in the mouthrinse solutions for 120 hrs, and changes in colour reflectance and surface roughness values were measured by UV light spectrophotometry (Vita Easyshade; VITA Zahnfabrik) and by profilometer device (MitutoyoSurftest SJ-301), respectively. The change of surface roughness was inspected by Scanning Electron Microscopy (SEM) and Atomic Force Microscopy (AFM). RESULTS There was a positive correlation between the ΔE and increase in the surface roughness. Two of the ceramic materials, IPS Empress and Lava Ultimate, were affected significantly by the treatment of the mouthrinse solutions (P<.05). The most affecting solution was Tantum Verde and the most affected material was Lava Ultimate. As expected, the most resistant material to ΔE and chemical corrosion was IPS e max CAD among the materials used. CONCLUSION This work implied that mouthrinse with lower alcohol content had less deteriorating effect on colour and on the surface morphology of the bioceramic materials. PMID:28680552

Maintaining the pluripotency of mouse embryonic stem cells on gold nanoparticle layers with nanoscale but not microscale surface roughness.

PubMed

Lyu, Zhonglin; Wang, Hongwei; Wang, Yanyun; Ding, Kaiguo; Liu, Huan; Yuan, Lin; Shi, Xiujuan; Wang, Mengmeng; Wang, Yanwei; Chen, Hong

2014-06-21

Efficient control of the self-renewal and pluripotency maintenance of embryonic stem cell (ESC) is a prerequisite for translating stem cell technologies to clinical applications. Surface topography is one of the most important factors that regulates cell behaviors. In the present study, micro/nano topographical structures composed of a gold nanoparticle layer (GNPL) with nano-, sub-micro-, and microscale surface roughnesses were used to study the roles of these structures in regulating the behaviors of mouse ESCs (mESCs) under feeder-free conditions. The distinctive results from Oct-4 immunofluorescence staining and quantitative real-time polymerase chain reaction (qPCR) demonstrate that nanoscale and low sub-microscale surface roughnesses (Rq less than 392 nm) are conducive to the long-term maintenance of mESC pluripotency, while high sub-microscale and microscale surface roughnesses (Rq greater than 573 nm) result in a significant loss of mESC pluripotency and a faster undirectional differentiation, particularly in long-term culture. Moreover, the likely signalling cascades engaged in the topological sensing of mESCs were investigated and their role in affecting the maintenance of the long-term cell pluripotency was discussed by analyzing the expression of proteins related to E-cadherin mediated cell-cell adhesions and integrin-mediated focal adhesions (FAs). Additionally, the conclusions from MTT, cell morphology staining and alkaline phosphatase (ALP) activity assays show that the surface roughness can provide a potent regulatory signal for various mESC behaviors, including cell attachment, proliferation and osteoinduction.

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

NASA Astrophysics Data System (ADS)

Sahin, Bünyamin; Bayansal, Fatih; Yüksel, Mustafa

2015-12-01

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

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.

Note: Erosion of W-Ni-Fe and W-Cu alloy electrodes in repetitive spark gaps.

PubMed

Wu, Jiawei; Han, Ruoyu; Ding, Weidong; Qiu, Aici; Tang, Junping

2018-02-01

A pair of W-Ni-Fe and W-Cu electrodes were tested under 100 kA level pulsed currents for 10 000 shots, respectively. Surface roughness and morphology characteristics of the two pairs of electrodes were obtained and compared. Experimental results indicated cracks divided the W-Cu electrode surface to polygons while the W-Ni-Fe electrode surface remained as a whole with pits and protrusions. Accordingly, the surface roughness of W-Ni-Fe electrodes increased to ∼3 μm while that of W-Cu electrodes reached ∼7 μm at the end of the test. The results reveal that the W-Ni-Fe alloy has a better erosion resistance and potential to be further applied in spark gaps.

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

NASA Astrophysics Data System (ADS)

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

2015-12-01

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

Modeling, investigation and formulation of hydrophobic coatings for potential self-cleaning applications

NASA Astrophysics Data System (ADS)

Rios, Pablo Fabian

Self-cleaning surfaces have received a great deal of attention, both in research and commercial applications. Transparent and non-transparent self-cleaning surfaces are highly desired. The Lotus flower is a symbol of purity in Asian cultures, even when rising from muddy waters it stays clean and untouched by dirt. The Lotus leaf "self-cleaning" surface is hydrophobic and rough, showing a two-layer morphology. While hydrophobicity produces a high contact angle, surface morphology reduces the adhesion of dirt and water to the surface, thus water drops slide easily across the leaf carrying the dirt particles with them. Nature example in the Lotus-effect and extensive scientific research on related fields have rooted wide acceptance that high hydrophobicity can be obtained only by a proper combination of surface chemistry and roughness. Most researchers relate hydrophobicity to a high contact angle. However, the contact angle is not the only parameter that defines liquid-solid interactions. An additional parameter, the sliding angle, related to the adhesion between the liquid drop and the solid surface is also important in cases where liquid sliding is involved, such as self-cleaning applications. In this work, it is postulated that wetting which is related to the contact angle, and interfacial adhesion, which is related to the sliding angle, are interdependent phenomena and have to be considered simultaneously. A variety of models that relate the sliding angle to forces developed along the contact line between a liquid drop and a solid surface have been proposed in the literature. A new model is proposed here that quantifies the drop sliding phenomenon, based also on the interfacial adhesion across the contact area of the liquid/solid interface. The effects of roughness and chemical composition on the contact and sliding angles of hydrophobic smooth and rough surfaces were studied theoretically and experimentally. The validity of the proposed model was investigated and compared with the existing models. Ultra-hydrophobic non-transparent and transparent coatings for potential self-cleaning applications were produced using hydrophobic chemistry and different configurations of roughening micro and nano-particles, however they present low adhesion and durability. Durability and stability enhancement of such coatings was attempted and improved by different methods.

Estimating small-scale roughness of a rock joint using TLS data

NASA Astrophysics Data System (ADS)

Bitenc, Maja; Kieffer, D. Scott; Khoshelham, Kourosh

2016-04-01

Roughness of a rock joint is an important parameter influencing rock mass stability. Besides the surface amplitude, also the roughness direction- and scale-dependency should be observed (i.e. 3D roughness). Up to now most of roughness measurements and parameters rely on point or profile data obtained on small samples, mostly in a laboratory. State-of-the-art remote sensing technologies supply 3D measurements of an in-situ rock surface and therefore enable a 3D roughness parameterization. Detailed morphology of a remote large-scale vertical structure can be best observed by Terrestrial Laser Scanning (TLS). In a short time and from distances of a few hundred meters, TLS provides relatively dense and precise point cloud. Sturzenegger and Stead [2009] showed that the TLS technology and careful fieldwork allow the extraction of first-order roughness profiles, i.e. the surface irregularities with a wavelength greater than about 10 cm. Our goal is to find the lower limit; this is, to define the smallest discernible detail, and appropriate measuring and processing steps to extract this detail from the TLS data. The smallest observable roughness amplitude depends on the TLS data precision, which is limited mostly by an inherent range error (noise). An influence of the TLS noise on the rock joint roughness was analyzed using highly precise reference data acquired by Advanced TOpometric Sensor (ATOS) on a 20x30 cm rock joint sample. ATOS data were interpolated into 1 mm grid, to which five levels (0.5, 1, 1.5, 2, 2.5 mm) of normally distributed noise were added. The 3D surfaces entered direction-dependent roughness parameter computation after Grasselli [2001]. Average roughness of noisy surfaces logarithmically increase with the noise level and is already doubled for 1 mm noise. Performing Monte Carlo simulation roughness parameter noise sensitivity was investigated. Distribution of roughness differences (roughness of noisy surfaces minus roughness of reference ATOS surface) is approximately normal. Standard deviation of differences on average slightly increases with the noise level, but is strongly dependent on the analysis direction. As proved by different researches within the field of signal, image and also TLS data processing, noise can be, to a certain extent, removed by a post-processing step called denoising. In this research, four denoising methods, namely discrete WT (DWT) and stationary WT (SWT), and classic NLM (NLM) and probabilistic NLM (PNLM), were used on noisy ATOS data. Results were compared based on the (i) height and (ii) roughness differences between denoised surfaces and reference ATOS surface, (iii) the peak signal-to-noise ratio (PSNR) and (iv) the visual check of denoised surface. Increased PSNRs and reduced roughness differences prove the importance of the TLS data denoising procedure. In case of SWT, NLM and PNLM the surface is mostly over smoothed, whereas in case of DWT some noise remains. References: - Grasselli, G. (2001). Shear strength of rock joints based on quantified surface description. École Polytechnique Fédérale de Lausanne. Lausanne, EPFL. - Sturzenegger, M. and D. Stead (2009). "Close-range terrestrial digital photogrammetry and terrestrial laser scanning for discontinuity characterization on rock cuts." Engineering Geology 106(3-4): 163-182.

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.

Synthesis and characterization of MoS2/Ti composite coatings on Ti6Al4V prepared by laser cladding

NASA Astrophysics Data System (ADS)

Yang, Rongjuan; Liu, Zongde; Wang, Yongtian; Yang, Guang; Li, Hongchuan

2013-02-01

The MoS2/Ti composite coating with sub-micron grade structure has been prepared on Ti6Al4V by laser method under argon protection. The morphology, microstructure, microhardness and friction coefficient of the coating were examined. The results indicated that the molybdenum disulfide was decomposed during melting and resolidification. The phase organization of composite coating mainly consisted of ternary element sulfides, molybdenum sulfides and titanium sulfides. The friction coefficient of and the surface roughness the MoS2/Ti coating were lower than those of Ti6Al4V. The composite coating exhibits excellent adhesion to the substrates, less surface roughness, good wear resistance and harder surface.

High Stability Pentacene Transistors Using Polymeric Dielectric Surface Modifier.

PubMed

Wang, Xiaohong; Lin, Guangqing; Li, Peng; Lv, Guoqiang; Qiu, Longzhen; Ding, Yunsheng

2015-08-01

1,6-bis(trichlorosilyl)hexane (C6Cl), polystyrene (PS), and cross-linked polystyrene (CPS) were investigated as gate dielectric modified layers for high performance organic transistors. The influence of the surface energy, roughness and morphology on the charge transport of the organic thin-film transistors (OTFTs) was investigated. The surface energy and roughness both affect the grain size of the pentacene films which will control the charge carrier mobility of the devices. Pentacene thin-film transistors fabricated on the CPS modified dielectric layers exhibited charge carrier mobility as high as 1.11 cm2 V-1 s-1. The bias stress stability for the CPS devices shows that the drain current only decays 1% after 1530 s and the mobility never decreases until 13530 s.

Topological and morphological analysis of gamma rays irradiated chitosan-poly (vinyl alcohol) blends using atomic force microscopy

NASA Astrophysics Data System (ADS)

Bhatt, Rinkesh; Bisen, D. S.; Bajpai, R.; Bajpai, A. K.

2017-04-01

In the present communication, binary blends of poly (vinyl alcohol) (PVA) and chitosan (CS) were prepared by solution cast method and the roughness parameters of PVA, native CS and CS-PVA blend films were determined using atomic force microscopy (AFM). Moreover, the changes in the morphology of the samples were also investigated after irradiation of gamma rays at absorbed dose of 1 Mrad and 10 Mrad for the scanning areas of 5×5 μm2, 10×10 μm2 and 20×20 μm2. Amplitude, statistical and spatial parameters, including line, 3D and 2D image profiles of the experimental surfaces were examined and compared to un-irradiated samples. For gamma irradiated CS-PVA blends the larger waviness over the surface was found as compared to un-irradiated CS-PVA blends but the values of average roughness for both the films were found almost same. The coefficient of skewness was positive for gamma irradiated CS-PVA blends which revealed the presence of more peaks than valleys on the blend surfaces.

Magnesium coated bioresorbable phosphate glass fibres: investigation of the interface between fibre and polyester matrices.

PubMed

Liu, Xiaoling; Grant, David M; Parsons, Andrew J; Harper, Lee T; Rudd, Chris D; Ahmed, Ifty

2013-01-01

Bioresorbable phosphate glass fibre reinforced polyester composites have been investigated as replacement for some traditional metallic orthopaedic implants, such as bone fracture fixation plates. However, composites tested revealed loss of the interfacial integrity after immersion within aqueous media which resulted in rapid loss of mechanical properties. Physical modification of fibres to change fibre surface morphology has been shown to be an effective method to improve fibre and matrix adhesion in composites. In this study, biodegradable magnesium which would gradually degrade to Mg(2+) in the human body was deposited via magnetron sputtering onto bioresorbable phosphate glass fibres to obtain roughened fibre surfaces. Fibre surface morphology after coating was observed using scanning electron microscope (SEM). The roughness profile and crystalline texture of the coatings were determined via atomic force microscope (AFM) and X-ray diffraction (XRD) analysis, respectively. The roughness of the coatings was seen to increase from 40 ± 1 nm to 80 ± 1 nm. The mechanical properties (tensile strength and modulus) of fibre with coatings decreased with increased magnesium coating thickness.

Magnesium Coated Bioresorbable Phosphate Glass Fibres: Investigation of the Interface between Fibre and Polyester Matrices

PubMed Central

Liu, Xiaoling; Grant, David M.; Parsons, Andrew J.; Harper, Lee T.; Rudd, Chris D.; Ahmed, Ifty

2013-01-01

Bioresorbable phosphate glass fibre reinforced polyester composites have been investigated as replacement for some traditional metallic orthopaedic implants, such as bone fracture fixation plates. However, composites tested revealed loss of the interfacial integrity after immersion within aqueous media which resulted in rapid loss of mechanical properties. Physical modification of fibres to change fibre surface morphology has been shown to be an effective method to improve fibre and matrix adhesion in composites. In this study, biodegradable magnesium which would gradually degrade to Mg2+ in the human body was deposited via magnetron sputtering onto bioresorbable phosphate glass fibres to obtain roughened fibre surfaces. Fibre surface morphology after coating was observed using scanning electron microscope (SEM). The roughness profile and crystalline texture of the coatings were determined via atomic force microscope (AFM) and X-ray diffraction (XRD) analysis, respectively. The roughness of the coatings was seen to increase from 40 ± 1 nm to 80 ± 1 nm. The mechanical properties (tensile strength and modulus) of fibre with coatings decreased with increased magnesium coating thickness. PMID:24066297

Control of crystallographic texture and surface morphology of Pt/Tio2 templates for enhanced PZT thin film texture.

PubMed

Fox, Austin J; Drawl, Bill; Fox, Glen R; Gibbons, Brady J; Trolier-McKinstry, Susan

2015-01-01

Optimized processing conditions for Pt/TiO2/SiO2/Si templating electrodes were investigated. These electrodes are used to obtain [111] textured thin film lead zirconate titanate (Pb[ZrxTi1-x ]O3 0 ≤ x ≤ 1) (PZT). Titanium deposited by dc magnetron sputtering yields [0001] texture on a thermally oxidized Si wafer. It was found that by optimizing deposition time, pressure, power, and the chamber pre-conditioning, the Ti texture could be maximized while maintaining low surface roughness. When oxidized, titanium yields [100]-oriented rutile. This seed layer has as low as a 4.6% lattice mismatch with [111] Pt; thus, it is possible to achieve strongly oriented [111] Pt. The quality of the orientation and surface roughness of the TiO2 and the Ti directly affect the achievable Pt texture and surface morphology. A transition between optimal crystallographic texture and the smoothest templating surface occurs at approximately 30 nm of original Ti thickness (45 nm TiO2). This corresponds to 0.5 nm (2 nm for TiO2) rms roughness as determined by atomic force microscopy and a full-width at half-maximum (FWHM) of the rocking curve 0002 (200) peak of 5.5/spl degrees/ (3.1/spl degrees/ for TiO2). A Pb[Zr0.52Ti 0.48]O3 layer was deposited and shown to template from the textured Pt electrode, with a maximum [111] Lotgering factor of 87% and a minimum 111 FWHM of 2.4/spl degrees/ at approximately 30 nm of original Ti.

Surface morphological evolution of epitaxial CrN(001) layers

NASA Astrophysics Data System (ADS)

Frederick, J. R.; Gall, D.

2005-09-01

CrN layers, 57 and 230 nm thick, were grown on MgO(001) at Ts=600-800 °C by ultrahigh-vacuum magnetron sputter deposition in pure N2 discharges from an oblique deposition angle α=80°. Layers grown at 600 °C nucleate as single crystals with a cube-on-cube epitaxial relationship with the substrate. However, rough surfaces with cauliflower-type morphologies cause the nucleation of misoriented CrN grains that develop into cone-shaped grains that protrude out of the epitaxial matrix to form triangular faceted surface mounds. The surface morphology of epitaxial CrN(001) grown at 700 °C is characterized by dendritic ridge patterns extending along the orthogonal <110> directions superposed by square-shaped super mounds with <100> edges. The ridge patterns are attributed to a Bales-Zangwill instability while the supermounds form due to atomic shadowing which leads to the formation of epitaxial inverted pyramids that are separated from the surrounding layer by tilted nanovoids. Growth at 800 °C yields complete single crystals with smooth surfaces. The root-mean-square surface roughness for 230-nm-thick layers decreases from 18.8 to 9.3 to 1.1 nm as Ts is raised from 600 to 700 to 800 °C. This steep decrease is due to a transition in the roughening mechanism from atomic shadowing to kinetic roughening. Atomic shadowing is dominant at 600 and 700 °C, where misoriented grains and supermounds, respectively, capture a larger fraction of the oblique deposition flux in comparison to the surrounding epitaxial matrix, resulting in a high roughening rate that is described by a power law with an exponent β>0.5. In contrast, kinetic roughening controls the surface morphology for Ts=800 °C, as well as the epitaxial fraction of the layers grown at 600 and 700 °C, yielding relatively smooth surfaces and β<=0.27.

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

PubMed

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

2018-02-01

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

Surface Morphology of Liquid and Solid Thin Films via X-Ray Reflectivity.

NASA Astrophysics Data System (ADS)

Shindler, Joseph Daniel

X-ray reflectivity can be used to measure the spatial variations in the electron density on length scales from Angstroms to microns. It is sensitive to atomic scale roughness, interdiffusion in buried layers, the thickness of multilayer stacks, and in-plane correlations in each of these cases. We have pioneered the use of a high intensity, moderate resolution configuration for x-ray reflectivity which utilizes a bent crystal graphite monochromator. With this technique we can obtain a beam intensity one hundred times greater than is possible using the high resolution rotating anode configuration, while we have shown that the resulting instrumental resolution is appropriate for the vast majority of thin film work. For all of the systems studied, we were able to measure the weak diffuse scattering signal to probe the in-plane length scales of interfacial roughness, a measurement which had previously only been attempted at synchrotron sources. Studied systems include thin films and surfaces with a wide range of structural order and surface morphologies. Interest in liquid films has been of a fundamental nature. Theories on the expected film evolution with changing thickness and temperature are currently being tested with scattering experiments. We have pursued the issues of film/substrate wetting and conformality, focussing on the temperature dependence of these phenomena near the triple point. Despite the heterogeneity of the substrate potential, we see a very sharp wetting transition at or near the triple point, although below the triple point the film is still smooth, consistent with a uniform layer. We also see a loss of conformality as the fluid films thicken; this is consistent with theory and with other recent experiments. The properties of a multilayer solid film depend not only on the magnitude of the roughness of each interface, but also on the conformality between interfaces and the length scales of the roughness--i.e., whether the roughness is on the atomic lengths of interdiffusion, crystalline order lengths of faceting, or even longer lengths due to other processes. In a joint project with Alcoa, we combined the methods of x-ray Bragg diffraction and small angle reflectivity to probe aluminum thin films as precursors to true multilayer films, correlating grain size and orientation with the magnitude and length-scales of surface roughness. We also correlated all film properties with such parameters as the deposition method, substrate roughness, and film thickness.

Diversity of dermal denticle structure in sharks: Skin surface roughness and three-dimensional morphology.

PubMed

Ankhelyi, Madeleine V; Wainwright, Dylan K; Lauder, George V

2018-05-29

Shark skin is covered with numerous placoid scales or dermal denticles. While previous research has used scanning electron microscopy and histology to demonstrate that denticles vary both around the body of a shark and among species, no previous study has quantified three-dimensional (3D) denticle structure and surface roughness to provide a quantitative analysis of skin surface texture. We quantified differences in denticle shape and size on the skin of three individual smooth dogfish sharks (Mustelus canis) using micro-CT scanning, gel-based surface profilometry, and histology. On each smooth dogfish, we imaged between 8 and 20 distinct areas on the body and fins, and obtained further comparative skin surface data from leopard, Atlantic sharpnose, shortfin mako, spiny dogfish, gulper, angel, and white sharks. We generated 3D images of individual denticles and measured denticle volume, surface area, and crown angle from the micro-CT scans. Surface profilometry was used to quantify metrology variables such as roughness, skew, kurtosis, and the height and spacing of surface features. These measurements confirmed that denticles on different body areas of smooth dogfish varied widely in size, shape, and spacing. Denticles near the snout are smooth, paver-like, and large relative to denticles on the body. Body denticles on smooth dogfish generally have between one and three distinct ridges, a diamond-like surface shape, and a dorsoventral gradient in spacing and roughness. Ridges were spaced on average 56 µm apart, and had a mean height of 6.5 µm, comparable to denticles from shortfin mako sharks, and with narrower spacing and lower heights than other species measured. We observed considerable variation in denticle structure among regions on the pectoral, dorsal, and caudal fins, including a leading-to-trailing edge gradient in roughness for each region. Surface roughness in smooth dogfish varied around the body from 3 to 42 microns. © 2018 Wiley Periodicals, Inc.

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.

Crystal truncation rods from miscut surfaces

DOE PAGES

Petach, Trevor A.; Mehta, Apurva; Toney, Michael F.; ...

2017-05-08

Crystal truncation rods are used to study surface and interface structure. Since real surfaces are always somewhat miscut from a low index plane, it is important to study the effect of miscuts on crystal truncation rods. We develop a model that describes the truncation rod scattering from miscut surfaces that have steps and terraces. We show that nonuniform terrace widths and jagged step edges are both forms of roughness that decrease the intensity of the rods. Nonuniform terrace widths also result in a broad peak that overlaps the rods. We use our model to characterize the terrace width distribution andmore » step edge jaggedness on three SrTiO 3 (001) samples, showing excellent agreement between the model and the data, confirmed by atomic force micrographs of the surface morphology. As a result, we expect our description of terrace roughness will apply to many surfaces, even those without obvious terracing.« less

Kinetic Monte Carlo Simulations of Rod Eutectics and the Surface Roughening Transition in Binary Alloys

NASA Technical Reports Server (NTRS)

Bentz, Daniel N.; Betush, William; Jackson, Kenneth A.

2003-01-01

In this paper we report on two related topics: Kinetic Monte Carlo simulations of the steady state growth of rod eutectics from the melt, and a study of the surface roughness of binary alloys. We have implemented a three dimensional kinetic Monte Carlo (kMC) simulation with diffusion by pair exchange only in the liquid phase. Entropies of fusion are first chosen to fit the surface roughness of the pure materials, and the bond energies are derived from the equilibrium phase diagram, by treating the solid and liquid as regular and ideal solutions respectively. A simple cubic lattice oriented in the {100} direction is used. Growth of the rods is initiated from columns of pure B material embedded in an A matrix, arranged in a close packed array with semi-periodic boundary conditions. The simulation cells typically have dimensions of 50 by 87 by 200 unit cells. Steady state growth is compliant with the Jackson-Hunt model. In the kMC simulations, using the spin-one Ising model, growth of each phase is faceted or nonfaceted phases depending on the entropy of fusion. There have been many studies of the surface roughening transition in single component systems, but none for binary alloy systems. The location of the surface roughening transition for the phases of a eutectic alloy determines whether the eutectic morphology will be regular or irregular. We have conducted a study of surface roughness on the spin-one Ising Model with diffusion using kMC. The surface roughness was found to scale with the melting temperature of the alloy as given by the liquidus line on the equilibrium phase diagram. The density of missing lateral bonds at the surface was used as a measure of surface roughness.

Coating stainless steel plates with Ag/TiO2 for chlorpyrifos decontamination

NASA Astrophysics Data System (ADS)

Abdel Fattah, Wafa I.; Gobara, Mohammed M.; El-Hotaby, Walid; Mostafa, Sherif F. M.; Ali, Ghareib W.

2016-05-01

Spray coatings of either nanosilver (Ag), titanium (TiO2) or nanosilver titanium (Ag/TiO2) on stainless steel substrates prepared by sol-gel process were successfully achieved. The efficiency of the Ag/TiO2 coat onto 316 stainless steel surface towards cloropyrifos degradation as a chemical warfare agent (CWA) was proved. The crystalline structure and morphological characterization, as well as surface roughness measurements, were assessed. X-ray diffraction results proved the crystalline TiO2 anatase phase. The uniform distribution of Ag along with TiO2 nanoparticles was evidenced through transmission electron microscopy and scanning electron microscopy mapping. The hydrophilic nature of individual Ag, TiO2 and Ag/TiO2 coats was proved by contact angle measurements. The loading of Ag nanoparticles influenced positively the Ag/TiO2 coats surface roughness. The photocatalytic cloropyrifos degradation achieved about 50% within one-hour post UV treatment proving, therefore, the promising Ag/TiO2 continued decontamination efficiency. In conclusion, tuning the physical and morphological properties of TiO2 coated on stainless steel surface could be significantly enhanced by Ag nanoparticles incorporation. The developed Ag/TiO2 coat could be conveniently applied as CWA decontaminant.

Dynamic Mechanical Properties and Fracture Surface Morphologies of Core-Shell Rubber (CSR) Toughened Epoxy at Liquid Nitrogen (Ln2) Temperatures

NASA Technical Reports Server (NTRS)

Wang, J.; Magee, D.; Schneider, J. A.

2009-01-01

The dynamic mechanical properties and fracture surface morphologies were evaluated for a commercial epoxy resin toughened with two types of core-shell rubber (CSR) toughening agents (Kane Ace(Registered TradeMark) MX130 and MX960). The impact resistance (R) was evaluated by the resulting breaking energy measured in Charpy impact tests conducted on an instrumented drop tower. The resulting fracture surface morphologies were examined using Scanning Electron Microscopy (SEM). Fractographic observations of the CSR toughened epoxy tested at ambient temperature, showed a fracture as characterized by slender dendrite textures with large voids. The increasing number of dendrites and decreasing size of scale-like texture with more CSR particles corresponded with increased R. As the temperature decreased to Liquid Nitrogen (LN 2), the fracture surfaces showed a fracture characterized by a rough, torn texture containing many river markings and deep furrows.

Tribological behaviors of UHMWPE composites with different counter surface morphologies

NASA Astrophysics Data System (ADS)

Wang, Yanzhen; Yin, Zhongwei; Li, Hulin; Gao, Gengyuan

2017-12-01

The influence of counter surface morphologies on hybrid glass fiber (GF) and carbon fiber (CF) filled ultrahigh molecular weight polyethylene (UHMWPE) were studied under various contact pressure and sliding speed against GCr15 steel in dry condition. The goals were to investigate the tribological behavior of GF/CF/UHMWPE composite as a kind of water lubricated journal bearing material. The friction and wear behavior of composites were examined using a pin-on-disc tribometer. The morphologies of the worn surface were examined by scanning electron microscopy (SEM) and laser 3D micro-imaging and profile measurement. Generally, the wear rate and friction coefficient of composites increase as the increment of counter surface roughness. The friction coefficient increases firstly and then decrease with an increase in sliding speed and contact pressure for counterface with Ra=0.2 and 3.5 μm, while the friction coefficient decreased for counterface with Ra=0.6 μm.

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

PubMed Central

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

2016-01-01

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

Diamond turning of thermoplastic polymers

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

Smith, E.; Scattergood, R.O.

Single point diamond turning studies were made using a series of thermoplastic polymers with different glass transition temperatures. Variations in surface morphology and surface roughness were observed as a function of cutting speed. Lower glass transition temperatures facilitate smoother surface cuts and better surface finish. This can be attributed to the frictional heating that occurs during machining. Because of the very low glass transition temperatures in polymeric compared to inorganic glasses, the precision machining response can be very speed sensitive.

Roughness transitions of diamond(100) induced by hydrogen-plasma treatment

NASA Astrophysics Data System (ADS)

Koslowski, B.; Strobel, S.; Wenig, M. J.; Ziemann, P.

To investigate the influence of hydrogen-plasma treatment on diamond(100) surfaces, heavily boron (B)-doped HPHT diamond crystals were mechanically and chemo-mechanically polished, and exposed to a microwave-assisted hydrogen plasma on a time scale of several minutes. The resulting surface morphology was analyzed on macroscopic scales by stylus profilometry (PFM) and on microscopic scales by STM and AFM. The polished samples have a roughness of typically 100 pmrms (PFM), with no obvious anisotropic structures at the surface. After exposure of the B-doped diamond(100) to the H-plasma, the roughness increases dramatically, and pronounced anisotropic structures appear, these being closely aligned with the crystallographic axis' and planes. An exposure for 3 minutes to the plasma leads to an increase of the roughness to 2-4 nmrms (STM), and a `brick-wall' pattern appears, formed by weak cusps running along <110>. Very frequently, the cusps are replaced by `negative' pyramids that are bordered by {11X} facets. After an exposure of an additional 5 minutes, the surface roughness of the B-doped samples increases further to 20-40 nmrms (STM), and frequently exhibits a regular pattern with structures at a characteristic length scale of about 100 nm. Those structures are aligned approximately with <110> and they are faceted with faces of approximately {XX1}. These results will be discussed in terms of strain relaxation, similar to the surface roughening observed on SiGe/Si and anisotropic etching.

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.

Effect of polymer coating on the osseointegration of CP-Ti dental implant

NASA Astrophysics Data System (ADS)

Al-Hassani, Emad; Al-Hassani, Fatima; Najim, Manar

2018-05-01

Modifications achieved coatings of titanium samples were investigated in order to improve their surface characteristics so as to facilitate bio-integration. Chitosan coating was use for commercial pure Ti alloys manufactured by two different methods in which commercial pure titanium rod converted in form of implant screw by using wire cut machine and lathe, second method included the used of powder technology for producing the implant screws. The coating process of chitosan polymer was carried out using advance technology (electrospnning process) to create fibrous structure from Nano to micro scale of the chitosan on the implant surface which result in a bioactive surface. The characterization includes; microstructure observation, surface chemical composition analysis (EDS), surface roughness (AFM), and the histological analysis. from the SEM No morphological differences were observed among the implants surfaces except for some inconsiderable morphological differences that results from the manufacturing process, by using EDX analysis the surfaces chemical compositions were completely changed and there was large decrease in the percentage of titanium element at the surface which indicates that the surface is covered with chitosan and had a new surface composition and topography. The sample was produced by powder technology process have higher roughness (845.36 nm) than sample produced by machining without any surface treatment (531.7nm),finally The histological view of implant samples after 4weeks of implantation, showed active bone formation in all implant surface which give clear indication of tissue acceptance.

Effects of Build Orientation on Surface Morphology and Bone Cell Activity of Additively Manufactured Ti6Al4V Specimens.

PubMed

Weißmann, Volker; Drescher, Philipp; Seitz, Hermann; Hansmann, Harald; Bader, Rainer; Seyfarth, Anika; Klinder, Annett; Jonitz-Heincke, Anika

2018-05-29

Additive manufacturing of lightweight or functional structures by selective laser beam (SLM) or electron beam melting (EBM) is widespread, especially in the field of medical applications. SLM and EBM processes were applied to prepare Ti6Al4V test specimens with different surface orientations (0°, 45° and 90°). Roughness measurements of the surfaces were conducted and cell behavior on these surfaces was analyzed. Hence, human osteoblasts were seeded on test specimens to determine cell viability (metabolic activity, live-dead staining) and gene expression of collagen type 1 (Col1A1), matrix metalloprotease (MMP) 1 and its natural inhibitor, TIMP1, after 3 and 7 days. The surface orientation of specimens during the manufacturing process significantly influenced the roughness. Surface roughness showed significant impact on cellular viability, whereas differences between the time points day 3 and 7 were not found. Collagen type 1 mRNA synthesis rates in human osteoblasts were enhanced with increasing roughness. Both manufacturing techniques further influenced the induction of bone formation process in the cell culture. Moreover, the relationship between osteoblastic collagen type 1 mRNA synthesis rates and specimen orientation during the building process could be characterized by functional formulas. These findings are useful in the designing of biomedical applications and medical devices.

Roughness evolution in dewetted Ag and Pt nanoscale films

NASA Astrophysics Data System (ADS)

Ruffino, F.; Grimaldi, M. G.

2018-01-01

The surface roughness of nanoscale metal systems plays a key role in determining the systems properties and, therefore, the electrical, optical, etc. response of nanodevices based on them. In this work, we experimentally analyze the roughness evolution in dewetting Ag and Pt films deposited on SiO2 substrate. In particular, after depositing 15 nm-thick Ag or Pt films on the SiO2 substrate, standard annealing processes were performed below the melting temperatures of the metals so to induce the solid-state dewetting of the films. The surface morphology evolution of the Ag and Pt films was studied by means of Atomic Force Microscopy analysis as a function of the annealing temperature T and of the annealing time t. In particular, these analysis allowed to quantify the roughness σ of the Ag and Pt films versus the annealing temperature T and the annealing time t. The analysis of these plots allowed us to draw combined insights on the dewetting process characteristics, on the dewetting-induced roughening properties, and on the material-dependent parameters by the comparison of the results obtained for the Ag film and the Pt film. These analysis, in addition, open perspectives towards the development of a method to produce supported metal films with controlled surface roughness for designed applications.

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.

An unscaled parameter to measure the order of surfaces: a new surface elaboration to increase cells adhesion.

PubMed

Bigerelle, M; Anselme, K; Dufresne, E; Hardouin, P; Iost, A

2002-08-01

We present a new parameter to quantify the order of a surface. This parameter is scale-independent and can be used to compare the organization of a surface at different scales of range and amplitude. To test the accuracy of this roughness parameter versus a hundred existing ones, we created an original statistical bootstrap method. In order to assess the physical relevance of this new parameter, we elaborated a great number of surfaces with various roughness amplitudes on titanium and titanium-based alloys using different physical processes. Then we studied the influence of the roughness amplitude on in vitro adhesion and proliferation of human osteoblasts. It was then shown that our new parameter best discriminates among the cell adhesion phenomena than others' parameters (Average roughness (Ra em leader )): cells adhere better on isotropic surfaces with a low order, provided this order is quantified on a scale that is more important than that of the cells. Additionally, on these low ordered metallic surfaces, the shape of the cells presents the same morphological aspect as that we can see on the human bone trabeculae. The method used to prepare these isotropic surfaces (electroerosion) could be undoubtedly and easily applied to prepare most biomaterials with complex geometries and to improve bone implant integration. Moreover, the new order parameter we developed may be particularly useful for the fundamental understanding of the mechanism of bone cell installation on a relief and of the formation of bone cell-material interface.

Influence of lead ions on the macromorphology of electrodeposited zinc

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

Tsuda, Tetsuaki; Tobias, Charles W.

1981-09-01

The morphology of zinc as it is electrodeposited from acid solutions demonstrates a remarkable imprint of electrolyte flow conditions. The development of macromorphology of zinc deposits has been investigated under galvanostatic conditions on a rotating plantinum disk electrode by use of photomacrography, scanning electron microscopy, electron probe microanalysis and Auger microprobe analysis. Logarithmic spiral markings, which reflect the hydrodynamic flow on a rotating disk, appear in a certain region of current density well below the limiting current density. Morphological observations revealed the major influence of trace lead ions on the amplifications of surface roughness through coalescence and preferred growth ofmore » initial protrusions. Results obtained from ultra-pure electrolyte suggest preferred crystal growth towards well-mixed orientation in the concentration field caused by slight differences in crystallization overpotential. A qualitative model involving a coupling mechanism between the evolving surface roughness and instability phenomena in the boundary layer is advanced to explain the formation of spiral patterns.« less

Substrate dependent hierarchical structures of RF sputtered ZnS films

NASA Astrophysics Data System (ADS)

Chalana, S. R.; Mahadevan Pillai, V. P.

2018-05-01

RF magnetron sputtering technique was employed to fabricate ZnS nanostructures with special emphasis given to study the effect of substrates (quartz, glass and quartz substrate pre-coated with Au, Ag, Cu and Pt) on the structure, surface evolution and optical properties. Type of substrate has a significant influence on the crystalline phase, film morphology, thickness and surface roughness. The present study elucidates the suitability of quartz substrate for the deposition of stable and highly crystalline ZnS films. We found that the role of metal layer on quartz substrate is substantial in the preparation of hierarchical ZnS structures and these structures are of great importance due to its high specific area and potential applications in various fields. A mechanism for morphological evolution of ZnS structures is also presented based on the roughness of substrates and primary nonlocal effects in sputtering. Furthermore, the findings suggest that a controlled growth of hierarchical ZnS structures may be achieved with an ordinary RF sputtering technique by changing the substrate type.

Nanoscale electro-structural characterisation of ohmic contacts formed on p-type implanted 4H-SiC

NASA Astrophysics Data System (ADS)

Frazzetto, Alessia; Giannazzo, Filippo; Lo Nigro, Raffaella; di Franco, Salvatore; Bongiorno, Corrado; Saggio, Mario; Zanetti, Edoardo; Raineri, Vito; Roccaforte, Fabrizio

2011-12-01

This work reports a nanoscale electro-structural characterisation of Ti/Al ohmic contacts formed on p-type Al-implanted silicon carbide (4H-SiC). The morphological and the electrical properties of the Al-implanted layer, annealed at 1700°C with or without a protective capping layer, and of the ohmic contacts were studied using atomic force microscopy [AFM], transmission line model measurements and local current measurements performed with conductive AFM. The characteristics of the contacts were significantly affected by the roughness of the underlying SiC. In particular, the surface roughness of the Al-implanted SiC regions annealed at 1700°C could be strongly reduced using a protective carbon capping layer during annealing. This latter resulted in an improved surface morphology and specific contact resistance of the Ti/Al ohmic contacts formed on these regions. The microstructure of the contacts was monitored by X-ray diffraction analysis and a cross-sectional transmission electron microscopy, and correlated with the electrical results.

Hybrid silicon honeycomb/organic solar cells with enhanced efficiency using surface etching.

PubMed

Liu, Ruiyuan; Sun, Teng; Liu, Jiawei; Wu, Shan; Sun, Baoquan

2016-06-24

Silicon (Si) nanostructure-based photovoltaic devices are attractive for their excellent optical and electrical performance, but show lower efficiency than their planar counterparts due to the increased surface recombination associated with the high surface area and roughness. Here, we demonstrate an efficiency enhancement for hybrid nanostructured Si/polymer solar cells based on a novel Si honeycomb (SiHC) structure using a simple etching method. SiHC structures are fabricated using a combination of nanosphere lithography and plasma treatment followed by a wet chemical post-etching. SiHC has shown superior light-trapping ability in comparison with the other Si nanostructures, along with a robust structure. Anisotropic tetramethylammonium hydroxide etching not only tunes the final surface morphologies of the nanostructures, but also reduces the surface roughness leading to a lower recombination rate in the hybrid solar cells. The suppressed recombination loss, benefiting from the reduced surface-to-volume ratio and roughness, has resulted in a high open-circuit voltage of 600 mV, a short-circuit current of 31.46 mA cm(-2) due to the light-trapping ability of the SiHCs, and yields a power conversion efficiency of 12.79% without any other device structure optimization.

An atomic-scale and high efficiency finishing method of zirconia ceramics by using magnetorheological finishing

NASA Astrophysics Data System (ADS)

Luo, Hu; Guo, Meijian; Yin, Shaohui; Chen, Fengjun; Huang, Shuai; Lu, Ange; Guo, Yuanfan

2018-06-01

Zirconia ceramics is a valuable crucial material for fabricating functional components applied in aerospace, biology, precision machinery, military industry and other fields. However, the properties of its high brittleness and high hardness could seriously reduce its finishing efficiency and surface quality by conventional processing technology. In this work, we present a high efficiency and high-quality finishing process by using magnetorheological finishing (MRF), which employs the permanent magnetic yoke with straight air gap as excitation unit. The sub-nanoscale surface roughness and damage free surface can be obtained after magnetorheological finishing. The XRD results and SEM morphologies confirmed that the mechanical shear removal with ductile modes are the dominant material removal mechanism for the magnetorheological finishing of zirconia ceramic. With the developed experimental apparatus, the effects of workpiece speed, trough speed and work gap on material removal rate and surface roughness were systematically investigated. Zirconia ceramics finished to ultra-smooth surface with surface roughness less than Ra 1 nm was repeatedly achieved during the parametric experiments. Additionally, the highest material removal rate exceeded 1 mg/min when using diamond as an abrasive particle. Magnetorheological finishing promises to be an adaptable and efficient method for zirconia ceramics finishing.

Effects of titania nanotubes with or without bovine serum albumin loaded on human gingival fibroblasts

PubMed Central

Liu, Xiangning; Zhou, Xiaosong; Li, Shaobing; Lai, Renfa; Zhou, Zhiying; Zhang, Ye; Zhou, Lei

2014-01-01

Modifying the surface of the transmucosal area is a key research area because this process positively affects the three functions of implants: attachment to soft tissue, inhibiting bacterial biofilm adhesion, and the preservation of the crestal bone. To exploit the potential of titania nanotube arrays (TNTs) with or without using bovine serum albumin (BSA) to modify the surface of a dental implant in contact with the transmucosal area, BSA was loaded into TNTs that were fabricated by anodizing Ti sheets; the physical characteristics of these arrays, including their morphology, chemical composition, surface roughness, contact angle, and surface free energy (SFE), were assessed. The effect of Ti surfaces with TNTs or TNTs-BSA on human gingival fibroblasts (HGFs) was determined by analyzing cell morphology, early adhesion, proliferation, type I collagen (COL-1) gene expression, and the extracellular secretion of COL-1. The results indicate that early HGF adhesion and spreading behavior is positively correlated with surface characteristics, including hydrophilicity, SFE, and surface roughness. Additionally, TNT surfaces not only promoted early HGF adhesion, but also promoted COL-1 secretion. BSA-loaded TNT surfaces promoted early HGF adhesion, while suppressing late proliferation and COL-1 secretion. Therefore, TNT-modified smooth surfaces are expected to be applicable for uses involving the transmucosal area. Further study is required to determine whether BSA-loaded TNT surfaces actually affect closed loop formation of connective tissue because BSA coating actions in vivo are very rapid. PMID:24623977

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

PubMed

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

2008-06-15

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

Simultaneous ion sputter polishing and deposition

NASA Technical Reports Server (NTRS)

Rutledge, S.; Banks, B.; Brdar, M.

1981-01-01

Results of experiments to study ion beam sputter polishing in conjunction with simultaneous deposition as a mean of polishing copper surfaces are presented. Two types of simultaneous ion sputter polishing and deposition were used in these experiments. The first type utilized sputter polishing simultaneous with vapor deposition, and the second type utilized sputter polishing simultaneous with sputter deposition. The etch and deposition rates of both techniques were studied, as well as the surface morphology and surface roughness.

Probing cluster surface morphology by cryo spectroscopy of N2 on cationic nickel clusters

NASA Astrophysics Data System (ADS)

Dillinger, Sebastian; Mohrbach, Jennifer; Niedner-Schatteburg, Gereon

2017-11-01

We present the cryogenic (26 K) IR spectra of selected [Nin(N2)m]+ (n = 5-20, m = 1 - mmax), which strongly reveal n- and m-dependent features in the N2 stretching region, in conjunction with density functional theory modeling of some of these findings. The observed spectral features allow us to refine the kinetic classification [cf. J. Mohrbach, S. Dillinger, and G. Niedner-Schatteburg, J. Chem. Phys. 147, 184304 (2017)] and to define four classes of structure related surface adsorption behavior: Class (1) of Ni6+, Ni13+, and Ni19+ are highly symmetrical clusters with all smooth surfaces of equally coordinated Ni atoms that entertain stepwise N2 adsorption up to stoichiometric N2:Nisurface saturation. Class (2) of Ni12+ and Ni18+ are highly symmetrical clusters minus one. Their relaxed smooth surfaces reorganize by enhanced N2 uptake toward some low coordinated Ni surface atoms with double N2 occupation. Class (3) of Ni5+ and Ni7+ through Ni11+ are small clusters of rough surfaces with low coordinated Ni surface atoms, and some reveal semi-internal Ni atoms of high next-neighbor coordination. Surface reorganization upon N2 uptake turns rough into rough surface by Ni atom migration and turns octahedral based structures into pentagonal bipyramidal structures. Class (4) of Ni14+ through Ni17+ and Ni20+ are large clusters with rough and smooth surface areas. They possess smooth icosahedral surfaces with some proximate capping atom(s) on one hemisphere of the icosahedron with the other one largely unaffected.

Nanoscopic morphological changes in yeast cell surfaces caused by oxidative stress: an atomic force microscopic study.

PubMed

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

2009-06-01

Nanoscopic changes in the cell surface morphology of the yeasts Saccharomyces cerevisiae (strain NCYC 1681) and Schizosaccharomyces pombe (strain DVPB 1354), due to their exposure to varying concentrations of hydrogen peroxide (oxidative stress), were investigated using an atomic force microscope (AFM). Increasing hydrogen peroxide concentration led to a decrease in cell viabilities and mean cell volumes, and an increase in the surface roughness of the yeasts. In addition, AFM studies revealed that oxidative stress caused cell compression in both S. cerevisiae and Schiz. pombe cells and an increase in the number of aged yeasts. These results confirmed the importance and usefulness of AFM in investigating the morphology of stressed microbial cells at the nanoscale. The results also provided novel information on the relative oxidative stress tolerance of S. cerevisiae and Schiz. pombe.

Growth evolution of AlN films on silicon (111) substrates by pulsed laser deposition

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

Wang, Haiyan; Wang, Wenliang; Yang, Weijia

2015-05-14

AlN films with various thicknesses have been grown on Si(111) substrates by pulsed laser deposition (PLD). The surface morphology and structural property of the as-grown AlN films have been investigated carefully to comprehensively explore the epitaxial behavior. The ∼2 nm-thick AlN film initially grown on Si substrate exhibits an atomically flat surface with a root-mean-square surface roughness of 0.23 nm. As the thickness increases, AlN grains gradually grow larger, causing a relatively rough surface. The surface morphology of ∼120 nm-thick AlN film indicates that AlN islands coalesce together and eventually form AlN layers. The decreasing growth rate from 240 to 180 nm/h is amore » direct evidence that the growth mode of AlN films grown on Si substrates by PLD changes from the islands growth to the layer growth. The evolution of AlN films throughout the growth is studied deeply, and its corresponding growth mechanism is hence proposed. These results are instructional for the growth of high-quality nitride films on Si substrates by PLD, and of great interest for the fabrication of AlN-based devices.« less

Impact of Interfacial Roughness on the Sorption Properties of Nanocast Polymers

DOE PAGES

Sridhar, Manasa; Gunugunuri, Krishna R.; Hu, Naiping; ...

2016-03-16

Nanocasting is an emerging method to prepare organic polymers with regular, nanometer pores using inorganic templates. This report assesses the impact of imperfect template replication on the sorption properties of such polymer castings. Existing X-ray diffraction data show that substantial diffuse scattering exists in the small-angle region even though TEM images show near perfect lattices of uniform pores. To assess the origin of the diffuse scattering, the morphology of the phenol - formaldehyde foams (PFF) was investigated by small-angle X-ray scattering (SAXS). The observed diffuse scattering is attributed to interfacial roughness due to fractal structures. Such roughness has a profoundmore » impact on the sorption properties. Conventional pore- filling models, for example, overestimate protein sorption capacity. A mathematical framework is presented to calculate sorption properties based on observed morphological parameters. The formalism uses the surface fractal dimension determined by SAXS in conjunction with nitrogen adsorption isotherms to predict lysozyme sorption. The results are consistent with measured lysozyme loading.« less

Structure zone diagram and particle incorporation of nickel brush plated composite coatings

PubMed Central

Isern, L.; Impey, S.; Almond, H.; Clouser, S. J.; Endrino, J. L.

2017-01-01

This work studies the deposition of aluminium-incorporated nickel coatings by brush electroplating, focusing on the electroplating setup and processing parameters. The setup was optimised in order to increase the volume of particle incorporation. The optimised design focused on increasing the plating solution flow to avoid sedimentation, and as a result the particle transport experienced a three-fold increase when compared with the traditional setup. The influence of bath load, current density and the brush material used was investigated. Both current density and brush material have a significant impact on the morphology and composition of the coatings. Higher current densities and non-abrasive brushes produce rough, particle-rich samples. Different combinations of these two parameters influence the surface characteristics differently, as illustrated in a Structure Zone Diagram. Finally, surfaces featuring crevices and peaks incorporate between 3.5 and 20 times more particles than smoother coatings. The presence of such features has been quantified using average surface roughness Ra and Abbott-Firestone curves. The combination of optimised setup and rough surface increased the particle content of the composite to 28 at.%. PMID:28300159

Structure zone diagram and particle incorporation of nickel brush plated composite coatings

NASA Astrophysics Data System (ADS)

Isern, L.; Impey, S.; Almond, H.; Clouser, S. J.; Endrino, J. L.

2017-03-01

This work studies the deposition of aluminium-incorporated nickel coatings by brush electroplating, focusing on the electroplating setup and processing parameters. The setup was optimised in order to increase the volume of particle incorporation. The optimised design focused on increasing the plating solution flow to avoid sedimentation, and as a result the particle transport experienced a three-fold increase when compared with the traditional setup. The influence of bath load, current density and the brush material used was investigated. Both current density and brush material have a significant impact on the morphology and composition of the coatings. Higher current densities and non-abrasive brushes produce rough, particle-rich samples. Different combinations of these two parameters influence the surface characteristics differently, as illustrated in a Structure Zone Diagram. Finally, surfaces featuring crevices and peaks incorporate between 3.5 and 20 times more particles than smoother coatings. The presence of such features has been quantified using average surface roughness Ra and Abbott-Firestone curves. The combination of optimised setup and rough surface increased the particle content of the composite to 28 at.%.

A step forward in the study of the electroerosion by optical methods

NASA Astrophysics Data System (ADS)

Aparicio, R.; Gale, M. F. Ruiz; Hogert, E. N.; Landau, M. R.; Gaggioli, y. N. G.

2003-05-01

This work develops two theoretical models of surfaces to explain the behavior of the light scattered by samples that suffers some alteration. In a first model, it is evaluated the mean intensity scattered by the sample, analyzing the different curves obtained as function of the eroded/total surface ratio. The theoretical results are compared with those obtained experimentally. It can be seen that there exists a strong relation between the electroerosion level and the light scattered by the sample. A second model analyzes a surface with random changes in its roughness. A translucent surface with its roughness changing in a controlled way is studied. Then, the correlation coefficient variation as function of the roughness variation is determined by the transmission speckle correlation method. The obtained experimental values are compared with those obtained with this model. In summary, it can be shown that the first- and second-order statistics properties of the transmitted or reflected light by a sample with a variable topography can be taken account as a parameter to analyze these morphologic changes.

Structure zone diagram and particle incorporation of nickel brush plated composite coatings.

PubMed

Isern, L; Impey, S; Almond, H; Clouser, S J; Endrino, J L

2017-03-16

This work studies the deposition of aluminium-incorporated nickel coatings by brush electroplating, focusing on the electroplating setup and processing parameters. The setup was optimised in order to increase the volume of particle incorporation. The optimised design focused on increasing the plating solution flow to avoid sedimentation, and as a result the particle transport experienced a three-fold increase when compared with the traditional setup. The influence of bath load, current density and the brush material used was investigated. Both current density and brush material have a significant impact on the morphology and composition of the coatings. Higher current densities and non-abrasive brushes produce rough, particle-rich samples. Different combinations of these two parameters influence the surface characteristics differently, as illustrated in a Structure Zone Diagram. Finally, surfaces featuring crevices and peaks incorporate between 3.5 and 20 times more particles than smoother coatings. The presence of such features has been quantified using average surface roughness Ra and Abbott-Firestone curves. The combination of optimised setup and rough surface increased the particle content of the composite to 28 at.%.

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

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

NASA Astrophysics Data System (ADS)

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

2018-04-01

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

High-Temperature Growth of GaN and Al x Ga1- x N via Ammonia-Based Metalorganic Molecular-Beam Epitaxy

NASA Astrophysics Data System (ADS)

Billingsley, Daniel; Henderson, Walter; Doolittle, W. Alan

2010-05-01

The effect of high-temperature growth on the crystalline quality and surface morphology of GaN and Al x Ga1- x N grown by ammonia-based metalorganic molecular-beam epitaxy (NH3-MOMBE) has been investigated as a means of producing atomically smooth films suitable for device structures. The effects of V/III ratio on the growth rate and surface morphology are described herein. The crystalline quality of both GaN and AlGaN was found to mimic that of the GaN templates, with (002) x-ray diffraction (XRD) full-widths at half- maximum (FWHMs) of ~350 arcsec. Nitrogen-rich growth conditions have been found to provide optimal surface morphologies with a root-mean-square (RMS) roughness of ~0.8 nm, yet excessive N-rich environments have been found to reduce the growth rate and result in the formation of faceted surface pitting. AlGaN exhibits a decreased growth rate, as compared with GaN, due to increased N recombination as a result of the increased pyrolysis of NH3 in the presence of Al. AlGaN films grown directly on GaN templates exhibited Pendellösung x-ray fringes, indicating an abrupt interface and a planar AlGaN film. AlGaN films grown for this study resulted in an optimal RMS roughness of ~0.85 nm with visible atomic steps.

RF plasma based selective modification of hydrophilic regions on super hydrophobic surface

NASA Astrophysics Data System (ADS)

Lee, Jaehyun; Hwang, Sangyeon; Cho, Dae-Hyun; Hong, Jungwoo; Shin, Jennifer H.; Byun, Doyoung

2017-02-01

Selective modification and regional alterations of the surface property have gained a great deal of attention to many engineers. In this paper, we present a simple, a cost-effective, and amendable reforming method for disparate patterns of hydrophilic regions on super-hydrophobic surfaces. Uniform super-hydrophobic layer (Contact angle; CA > 150°, root mean square (RMS) roughness ∼0.28 nm) can be formed using the atmospheric radio frequency (RF) plasma on top of the selective hydrophilic (CA ∼ 70°, RMS roughness ∼0.34 nm) patterns imprinted by electrohydrodynamic (EHD) jet printing technology with polar alcohols (butyl carbitol or ethanol). The wettability of the modified surface was investigated qualitatively utilizing scanning electron microscopy (SEM), atomic force microscopy (AFM), and wavelength scanning interferometer (WSI). Secondary ion mass spectroscopy (SIMS) analysis showed that the alcohol addiction reaction changed the types of radicals on the super-hydrophobic surface. The wettability was found to depend sensitively on chemical radicals on the surface, not on surface morphology (particle size and surface roughness). Furthermore, three different kinds of representative hydrophilic samples (polystyrene nano-particle aqueous solution, Salmonella bacteria medium, and poly(3,4-ethylenediocythiophene) ink) were tested for uniform deposition onto the desired hydrophilic regions. This simple strategy would have broad applications in various research fields that require selective deposition of target materials.

Effects of laser shock peening with contacting foil on micro laser texturing surface of Ti6Al4V

NASA Astrophysics Data System (ADS)

Dai, Fengze; Zhang, Zidong; Ren, Xudong; Lu, Jinzhong; Huang, Shu

2018-02-01

Ti6Al4V samples with micro-dimple arrays were subjected to laser shock peening in contact with foil (HCLSP). The surface roughness, micro-hardness, the residual stress distribution and the surface morphology of the micro-dimple arrays were studied to evaluate the effects of HCLSP. Moreover, the surface topography of the foils in contact was also analyzed. The gap existence between the foil and the to-be treated surface led the mechanism of HCLSP to be different compared to regular laser shock peening. The surface roughness reduction, the work-hardening effects, the compressive residual stress and the micro crack enclosure were achieved. A simplified ball-hitting-surface model was utilized to analyze the HCLSP impact. The model could well explain the experimental results. When treated by the HCLSP with H62 foil at the laser power density of 4.24 GW/cm2, the Ti6Al4V samples with micro-dimple arrays exhibit well surface topography and mechanical performance.

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.

Surface study of irradiated sapphires from Phrae Province, Thailand using AFM

NASA Astrophysics Data System (ADS)

Monarumit, N.; Jivanantaka, P.; Mogmued, J.; Lhuaamporn, T.; Satitkune, S.

2017-09-01

The irradiation is one of the gemstone enhancements for improving the gem quality. Typically, there are many varieties of irradiated gemstones in the gem market such as diamond, topaz, and sapphire. However, it is hard to identify the gemstones before and after irradiation. The aim of this study is to analyze the surface morphology for classifying the pristine and irradiated sapphires using atomic force microscope (AFM). In this study, the sapphire samples were collected from Phrae Province, Thailand. The samples were irradiated by high energy electron beam for a dose of ionizing radiation at 40,000 kGy. As the results, the surface morphology of pristine sapphires shows regular atomic arrangement, whereas, the surface morphology of irradiated sapphires shows the nano-channel observed by the 2D and 3D AFM images. The atomic step height and root mean square roughness have changed after irradiation due to the micro-structural defect on the sapphire surface. Therefore, this study is a frontier application for sapphire identification before and after irradiation.

Impact of uneven sample morphology on mass resolving power in linear MALDI-TOF mass spectrometry: A comprehensive theoretical investigation.

PubMed

Cai, Yi-Hong; Wang, Yi-Sheng

2018-04-01

This work discusses the correlation between the mass resolving power of matrix-assisted laser desorption/ionization time-of-flight mass analyzers and extraction condition with an uneven sample morphology. Previous theoretical calculations show that the optimum extraction condition for flat samples involves an ideal ion source design and extraction delay. A general expression of spectral feature takes into account ion initial velocity, and extraction delay is derived in the current study. The new expression extends the comprehensive calculation to uneven sample surfaces and above 90% Maxell-Boltzmann initial velocity distribution of ions to account for imperfect ionization condition. Calculation shows that the impact of uneven sample surface or initial spatial spread of ions is negligible when the extraction delay is away from the ideal value. When the extraction delay approaches the optimum value, the flight-time topology shows a characteristic curve shape, and the time-domain mass spectral feature broadens with an increase in initial spatial spread of ions. For protonated 2,5-dihydroxybenzoic acid, the mass resolving power obtained from a sample of 3-μm surface roughness is approximately 3.3 times lower than that of flat samples. For ions of m/z 3000 coexpanded with 2,5-dihydroxybenzoic acid, the mass resolving power in the 3-μm surface roughness case only reduces roughly 7%. Comprehensive calculations also show that the mass resolving power of lighter ions is more sensitive to the accuracy of the extraction delay than heavier ions. Copyright © 2018 John Wiley & Sons, Ltd.

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

NASA Astrophysics Data System (ADS)

Sui, Xin; Wang, Baohui; Wu, Haiming

2018-02-01

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

Micro-topography, rock surface modelling and minerology of notches in Mount Carmel

NASA Astrophysics Data System (ADS)

Brook, Anna; Ben-Binyamin, Atzmon; Shtober-Zisu, Nurit

2016-04-01

Notches are defined as horizontal concaved indentations developed on slopes or cliffs in a basic "C" shape regardless of their location or formation process. Many studies have proclaimed that notches are associated with coastal processes where rocky shore faces are back carved, parallel to sea level by a combination of physical and biological abrasion, and by chemical and biological dissolution. The notches morphologies are various and depend on the lithology, climate, and environment history. These changes involve complex volumetric effects such as weathering and surface mineral dissolution. The main impetus for the present paper is to advance the modeling and the 3D complex pattern reconstruction of notch's cavity surface and detailed shapes and to assess the association between the morphological structures observed upon the notch parts and the fine scale mineralogical composition of the rock. The reconstruction of 3D surfaces using point clouds scanned data is a known problem in computer graphics. Several approaches are based on combinatorial structures, such as Delaunay triangulations, alpha shapes, or Voronoi diagrams. These schemes typically create a triangle mesh that interpolates all or most of the points. In the presence of noisy data, resulting surface is often jagged, and is therefore smoothed or refit to the points in subsequent processing. Fast Fourier Transform (FFT) is a common technique for solving dense, periodic Poisson systems. However, the FFT requires longer time and larger space, quickly becoming prohibitive for fine resolutions. The Poisson approach's key element is the observation that inward normal field of the boundary can be inferred as the gradient of a three dimensional solid indicator function. Thus, the generation of a watertight mesh can be obtained by: (1) transforming the oriented point samples into a continuous vector field referred to as the relationship between the gradient of the indicator function and an integral of surface normals. The computation of the indicator function is reduced to (2) finding a scalar function whose gradients best match the vector field. Point cloud input gives enough information for the approximation of the surface integral with discrete summation. A set of points used for the portioning of the whole scene into distinct patches and also for the surface integral scaled by the patch's area. (3) Extracting the appropriate iso-surface. The roughness spatial variation was calculated according to: 1) removal of the regional slope effect is a pre-step for the surface roughness indices calculation (regression surface is reduced from the original iso-surface model to produce residuals features, surface roughness, from which it possible to calculate the variogram of the residuals), 2) Semivariogram is used to determine the optimal window size for image texture analysis. Mineral composition and structure of the different patches and components define its solubility implying thus upon the micro-morphological differences. Spectral measurements taken in the field and in the lab will be constructed to spectral libraries representing the notch's visor, cavity and floor. The VIS-NIR, SWIR and MIR reflectance data measured by the different types of spectrometers will not be mixed for future evaluation of mineral identification. The constructed spectral libraries was analyzed and processed for the characterization of spectral features of samples. The spectral features were compared with various well characterized resampled mineral spectral libraries for identification of the forming minerals. The mineral composition is defined by spectroscopy and used to capture the areas corresponding to different patterns of micro roughness along the notch's surface. The suggested roughness and 3D surface reconstruction employ real data acquired by the Terrestrial Light and Range Detection (t-LiDAR) scanner. The project stresses an interdisciplinary approach to map the mineral variations along the notch's different components corresponding to the roughness surface changes.

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.

Highly roughened polycaprolactone surfaces using oxygen plasma-etching and in vitro mineralization for bone tissue regeneration: fabrication, characterization, and cellular activities.

PubMed

Kim, YongBok; Kim, GeunHyung

2015-01-01

Herein, poly(ɛ-caprolactone) (PCL) surfaces were treated to form various roughness values (R(a)=290-445 nm) and polar functional groups on the surfaces using a plasma-etching process, followed by immersion into simulated body fluid (SBF) for apatite formation. The surface morphology, chemical composition, and mean roughness of the plasma-etched PCL surfaces were measured, and various physical and morphological properties (water contact angles, protein absorption ability, and crystallite size of the apatite layer) of the in vitro mineralized PCL surfaces were evaluated. The roughened PCL surface P-3, which was treated with a sufficient plasma exposure time (4 h), achieved homogeneously distributed apatite formation after soaking in SBF for 7 days, as compared with other surfaces that were untreated or plasma-treated for 30 min or 2 h. Furthermore, to demonstrate their feasibility as a biomimetic surface, pre-osteoblast cells (MC3T3-E1) were cultured on the mineralized PCL surfaces, and cell viability, DAPI-phalloidin fluorescence assay, and alizarin red-staining of the P-3 surface were highly improved compared to the P-1 surface treated with a 30-min plasma exposure time; compared to untreated mineralized PCL surface (N-P), P-3 showed even greater improvements in cell viability and DAPI-phalloidin fluorescence assay. Based on these results, we found that the mineralized PCL surface supplemented with the appropriate plasma treatment can be implicitly helpful to achieve rapid hard tissue regeneration. Copyright © 2014 Elsevier B.V. All rights reserved.

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.

TiO2 nanowire-templated hierarchical nanowire network as water-repelling coating

NASA Astrophysics Data System (ADS)

Hang, Tian; Chen, Hui-Jiuan; Xiao, Shuai; Yang, Chengduan; Chen, Meiwan; Tao, Jun; Shieh, Han-ping; Yang, Bo-ru; Liu, Chuan; Xie, Xi

2017-12-01

Extraordinary water-repelling properties of superhydrophobic surfaces make them novel candidates for a great variety of potential applications. A general approach to achieve superhydrophobicity requires low-energy coating on the surface and roughness on nano- and micrometre scale. However, typical construction of superhydrophobic surfaces with micro-nano structure through top-down fabrication is restricted by sophisticated fabrication techniques and limited choices of substrate materials. Micro-nanoscale topographies templated by conventional microparticles through surface coating may produce large variations in roughness and uncontrollable defects, resulting in poorly controlled surface morphology and wettability. In this work, micro-nanoscale hierarchical nanowire network was fabricated to construct self-cleaning coating using one-dimensional TiO2 nanowires as microscale templates. Hierarchical structure with homogeneous morphology was achieved by branching ZnO nanowires on the TiO2 nanowire backbones through hydrothermal reaction. The hierarchical nanowire network displayed homogeneous micro/nano-topography, in contrast to hierarchical structure templated by traditional microparticles. This hierarchical nanowire network film exhibited high repellency to both water and cell culture medium after functionalization with fluorinated organic molecules. The hierarchical structure templated by TiO2 nanowire coating significantly increased the surface superhydrophobicity compared to vertical ZnO nanowires with nanotopography alone. Our results demonstrated a promising strategy of using nanowires as microscale templates for the rational design of hierarchical coatings with desired superhydrophobicity that can also be applied to various substrate materials.

TiO2 nanowire-templated hierarchical nanowire network as water-repelling coating

PubMed Central

Hang, Tian; Chen, Hui-Jiuan; Xiao, Shuai; Yang, Chengduan; Chen, Meiwan; Tao, Jun; Shieh, Han-ping; Yang, Bo-ru; Liu, Chuan

2017-01-01

Extraordinary water-repelling properties of superhydrophobic surfaces make them novel candidates for a great variety of potential applications. A general approach to achieve superhydrophobicity requires low-energy coating on the surface and roughness on nano- and micrometre scale. However, typical construction of superhydrophobic surfaces with micro-nano structure through top-down fabrication is restricted by sophisticated fabrication techniques and limited choices of substrate materials. Micro-nanoscale topographies templated by conventional microparticles through surface coating may produce large variations in roughness and uncontrollable defects, resulting in poorly controlled surface morphology and wettability. In this work, micro-nanoscale hierarchical nanowire network was fabricated to construct self-cleaning coating using one-dimensional TiO2 nanowires as microscale templates. Hierarchical structure with homogeneous morphology was achieved by branching ZnO nanowires on the TiO2 nanowire backbones through hydrothermal reaction. The hierarchical nanowire network displayed homogeneous micro/nano-topography, in contrast to hierarchical structure templated by traditional microparticles. This hierarchical nanowire network film exhibited high repellency to both water and cell culture medium after functionalization with fluorinated organic molecules. The hierarchical structure templated by TiO2 nanowire coating significantly increased the surface superhydrophobicity compared to vertical ZnO nanowires with nanotopography alone. Our results demonstrated a promising strategy of using nanowires as microscale templates for the rational design of hierarchical coatings with desired superhydrophobicity that can also be applied to various substrate materials. PMID:29308265

Real time measurements of surface growth evolution in magnetron sputtered single crystal Mo/V superlattices using in situ reflection high energy electron diffraction analysis

NASA Astrophysics Data System (ADS)

Svedberg, E. B.; Birch, J.; Edvardsson, C. N. L.; Sundgren, J.-E.

1999-07-01

The use of video recording of reflection high energy electron diffraction (RHEED) patterns for assessing the dynamic evolution of the surface morphology and crystallinity during growth was evaluated. As an example, Mo/V(001) superlattices with varying layer thickness (with periods Λ of 2.5 to 8.9 nm and a constant Mo:V ratio of 1:1) were examined. During the deposition, changes from two- to three-dimensional growth were observed in situ. From prior transmission electron microscopy (TEM) and X-ray diffraction (XRD) studies, it is known that this transition is associated with a critical thickness and concurrent roughening of the V layer. Video recording and subsequent image and data processing allowed the surface morphology to be continuously followed during growth. Post-growth analyses of the recorded data provided the evolution of surface lattice parameters and short range [1-2 monolayer (ML)] surface roughnesses with a time resolution of 200-400 ms (0.02-0.04 nm thickness resolution). During growth of Mo, a smoothening effect could be observed while the growth of V evidently increased the surface roughness from 1 to 2 ML. Furthermore, the onset of coherency strain relaxation of the topmost growing layers was observed to occur at 2.0-2.5 nm layer thicknesses for both materials, which is in qualitative agreement with theoretical predictions.

Effects of wettability and interfacial nanobubbles on flow through structured nanochannels: an investigation of molecular dynamics

NASA Astrophysics Data System (ADS)

Yen, Tsu-Hsu

2015-12-01

Solid-fluid boundary conditions are strongly influenced by a number of factors, including the intrinsic properties of the solid/fluid materials, surface roughness, wettability, and the presence of interfacial nanobubbles (INBs). The interconnected nature of these factors means that they should be considered jointly. This paper employs molecular dynamics (MD) simulation in a series of studies aimed at elucidating the influence of wettability in boundary behaviour and the accumulation of interfacial gas. Specifically, we examined the relationship between effective slip length, the morphology of nanobubbles, and wettability. Two methods were employed for the promotion of hydrophobicity between two structured substrates with similar intrinsic contact angles. We also compared anisotropic and isotropic atomic arrangements in the form of graphite and Si(100), respectively. A physical method was employed to deal with variations in surface roughness, whereas a chemical method was used to adjust the wall-fluid interaction energy (ɛwf). We first compared the characteristic properties of wettability, including contact angle and fluid density within the cavity. We then investigated the means by which variations in solid-fluid interfacial wettability affect interfacial gas molecules. Our results reveal that the morphology of INB on a patterned substrate is determined by wettability as well as the methods employed for the promotion of hydrophobicity. The present study also illustrates the means by which the multiple effects of the atomic arrangement of solids, surface roughness, wettability and INB influence effective slip length.

Influence of particle size on Cutting Forces and Surface Roughness in Machining of B4Cp - 6061 Aluminium Matrix Composites

NASA Astrophysics Data System (ADS)

Hiremath, Vijaykumar; Badiger, Pradeep; Auradi, V.; Dundur, S. T.; Kori, S. A.

2016-02-01

Amongst advanced materials, metal matrix composites (MMC) are gaining importance as materials for structural applications in particular, particulate reinforced aluminium MMCs have received considerable attention due to their superior properties such as high strength to weight ratio, excellent low-temperature performance, high wear resistance, high thermal conductivity. The present study aims at studying and comparing the machinability aspects of B4Cp reinforced 6061Al alloy metal matrix composites reinforced with 37μm and 88μm particulates produced by stir casting method. The micro structural characterization of the prepared composites is done using Scanning Electron Microscopy equipped with EDX analysis (Hitachi Su-1500 model) to identify morphology and distribution of B4C particles in the 6061Al matrix. The specimens are turned on a conventional lathe machine using a Polly crystalline Diamond (PCD) tool to study the effect of particle size on the cutting forces and the surface roughness under varying machinability parameters viz., Cutting speed (29-45 m/min.), Feed rate (0.11-0.33 mm/rev.) and depth of cut (0.5-1mm). Results of micro structural characterization revealed fairly uniform distribution of B4C particles (in both cases i.e., 37μm and 88μm) in 6061Al matrix. The surface roughness of the composite is influenced by cutting speed. The feed rate and depth of cut have a negative influence on surface roughness. The cutting forces decreased with increase in cutting speed whereas cutting forces increased with increase in feed and depth of cut. Higher cutting forces are noticed while machining Al6061 base alloy compared to reinforced composites. Surface finish is high during turning of the 6061Al base alloy and surface roughness is high with 88μm size particle reinforced composites. As the particle size increases Surface roughness also increases.

Growth of porous anodized alumina on the sputtered aluminum films with 2D-3D morphology for high specific surface area

NASA Astrophysics Data System (ADS)

Liao, M. W.; Chung, C. K.

2014-08-01

The porous anodic aluminum oxide (AAO) with high-aspect-ratio pore channels is widely used as a template for fabricating nanowires or other one-dimensional (1D) nanostructures. The high specific surface area of AAO can also be applied to the super capacitor and the supporting substrate for catalysis. The rough surface could be helpful to enhance specific surface area but it generally results in electrical field concentration even to ruin AAO. In this article, the aluminum (Al) films with the varied 2D-3D morphology on Si substrates were prepared using magnetron sputtering at a power of 50 W-185 W for 1 h at a working pressure of 2.5 × 10-1 Pa. Then, AAO was fabricated from the different Al films by means of one-step hybrid pulse anodizing (HPA) between the positive 40 V and the negative -2 V (1 s:1 s) for 3 min in 0.3 M oxalic acid at a room temperature. The microstructure and morphology of Al films were characterized by X-ray diffraction, scanning electron microscope and atomic force microscope, respectively. Some hillocks formed at the high target power could be attributed to the grain texture growth in the normal orientation of Al(1 1 1). The 3D porous AAO structure which is different from the conventional 2D planar one has been successfully demonstrated using HPA on the film with greatly rough hillock-surface formed at the highest power of 185 W. It offers a potential application of the new 3D AAO to high specific surface area devices.

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

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

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

2017-08-03

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

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

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

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

2017-07-12

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

Physical-Mechanical Properties and Micromorphology of Calcium Cements Exposed to Polyacrylic and Phosphoric Acids.

PubMed

de Souza, Gustavo Fernandes; Arrais, Ana Beatriz; Aragão, Cícero Flávio Soares; Ferreira, Isana Alvares; Borges, Boniek Castillo Dutra

2018-01-01

To evaluate if physical and mechanical properties of self-curing calcium hydroxide cements were affected by contact with polyacrylic and phosphoric acids. Resin-containing (Life (LF)) and resin-free (Hydro C (HyC)) materials were subjected to polyacrylic acid conditioning and rinsing (POL); phosphoric acid conditioning and rinsing (PHO); rinsing only; and no treatment ( n = 10). Water sorption/solubility, release of hydroxyl ions (pH), roughness (Ra), and impact resistance were evaluated. Additional samples ( n = 1) were prepared for scanning electron microscopy (SEM) analysis of the surface morphology. Data were analyzed by two-way ANOVA and Tukey post hoc test ( P < 0.05). Water sorption was significantly higher for LF when in contact with PHO and lower for POL ( P < 0.05). The mean solubility was higher with POL for both cements ( P < 0.05). PHO increased the mean surface roughness for HyC ( P < 0.01); a significant decrease was noted for LF after contact with both acids ( P < 0.01). PHO promoted lower release of hydroxyl ions on both cements ( P < 0.05). For LF, rinsing, PHO, and POL presented similar morphology, differing from the control group. For HyC, PHO and POL presented similar morphology, differing from the control group. PHO had a negative effect on the physical properties of the cements tested, except for the solubility test. POL affected roughness and solubility of HyC cement. Clinical procedures that require polyacrylic and phosphoric acid conditioning must be done carefully on self-curing calcium hydroxide cements in order to avoid negative impact on their properties.

The nucleus of Comet Borrelly: A study of morphology and surface brightness

USGS Publications Warehouse

Oberst, J.; Howington-Kraus, E.; Kirk, R.; Soderblom, L.; Buratti, B.; Hicks, M.; Nelson, R.; Britt, D.

2004-01-01

Stereo images obtained during the DS1 flyby were analyzed to derive a topographic model for the nucleus of Comet 19P/Borrelly for morphologic and photometric studies. The elongated nucleus has an overall concave shape, resembling a peanut, with the lower end tilted towards the camera. The bimodal character of surface-slopes and curvatures support the idea that the nucleus is a gravitational aggregate, consisting of two fragments in contact. Our photometric modeling suggests that topographic shading effects on Borrelly's surface are very minor (<10%) at the given resolution of the terrain model. Instead, albedo effects are thought to dominate Borrelly's large variations in surface brightness. With 90% of the visible surface having single scattering albedos between 0.008 and 0.024, Borrelly is confirmed to be among the darkest of the known Solar System objects. Photometrically corrected images emphasize that the nucleus has distinct, contiguous terrains covered with either bright or dark, smooth or mottled materials. Also, mapping of the changes in surface brightness with phase angle suggests that terrain roughness at subpixel scale is not uniform over the nucleus. High surface roughness is noted in particular near the transition between the upper and lower end of the nucleus, as well as near the presumed source region of Borrelly's main jets. Borrelly's surface is complex and characterized by distinct types of materials that have different compositional and/or physical properties. ?? 2003 Elsevier Inc. All rights reserved.

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

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

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

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

Characteristic of Low Temperature Carburized Austenitic Stainless Steel

NASA Astrophysics Data System (ADS)

Istiroyah; Pamungkas, M. A.; Saroja, G.; Ghufron, M.; Juwono, A. M.

2018-01-01

Low temperature carburizing process has been carried out on austenitic stainless steel (ASS) type AISI 316L, that contain chromium in above 12 at%. Therefore, conventional heat treatment processes that are usually carried out at high temperatures are not applicable. The sensitization process due to chromium migration from the grain boundary will lead to stress corrosion crack and decrease the corrosion resistance of the steel. In this study, the carburizing process was carried out at low temperatures below 500 °C. Surface morphology and mechanical properties of carburized specimens were investigated using optical microscopy, non destructive profilometer, and Vicker microhardness. The surface roughness analysis show the carburising process improves the roughness of ASS surface. This improvement is due to the adsorption of carbon atoms on the surface of the specimen. Likewise, the hardness test results indicate the carburising process increases the hardness of ASS.

Controlled nanopatterning & modifications of materials by energetic ions

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

Sinha, O. P.

Compound semiconductors (InP, InAs and GaSb) has been exposed to energetic 3 keV Ar{sup +} ions for a varying fluence range of 10{sup 13} ions/cm{sup 2} to 10{sup 18} ions/cm{sup 2} at room temperature. Morphological modifications of the irradiated surfaces have been investigated by Scanning Tunneling Microscopy (STM) in UHV conditions. It is observed that InP and GaSb have fluence dependent nanopattering e.g. nanoneedle, aligned nanodots, superimposed nanodots ripple like structures while InAs has little fluence dependent behaviour indicating materials dependent growth of features on irradiated surfaces. Moreover, surface roughness and wavelength of the features are also depending on themore » materials and fluences. The RMS surface roughness has been found to be increased rapidly in the early stage of irradiation followed by slower escalate rate and later tends to saturate indicating influence of the nonlinear processes.« less

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

DOE PAGES

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

2015-09-29

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

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

NASA Astrophysics Data System (ADS)

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

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

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.

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

PubMed

Deng, Guoliang; Feng, Guoying; Zhou, Shouhuan

2017-04-03

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

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

PubMed

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

2015-01-20

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

Robust surface roughness indices and morphological interpretation

NASA Astrophysics Data System (ADS)

Trevisani, Sebastiano; Rocca, Michele

2016-04-01

Geostatistical-based image/surface texture indices based on variogram (Atkison and Lewis, 2000; Herzfeld and Higginson, 1996; Trevisani et al., 2012) and on its robust variant MAD (median absolute differences, Trevisani and Rocca, 2015) offer powerful tools for the analysis and interpretation of surface morphology (potentially not limited to solid earth). In particular, the proposed robust index (Trevisani and Rocca, 2015) with its implementation based on local kernels permits the derivation of a wide set of robust and customizable geomorphometric indices capable to outline specific aspects of surface texture. The stability of MAD in presence of signal noise and abrupt changes in spatial variability is well suited for the analysis of high-resolution digital terrain models. Moreover, the implementation of MAD by means of a pixel-centered perspective based on local kernels, with some analogies to the local binary pattern approach (Lucieer and Stein, 2005; Ojala et al., 2002), permits to create custom roughness indices capable to outline different aspects of surface roughness (Grohmann et al., 2011; Smith, 2015). In the proposed poster, some potentialities of the new indices in the context of geomorphometry and landscape analysis will be presented. At same time, challenges and future developments related to the proposed indices will be outlined. Atkinson, P.M., Lewis, P., 2000. Geostatistical classification for remote sensing: an introduction. Computers & Geosciences 26, 361-371. Grohmann, C.H., Smith, M.J., Riccomini, C., 2011. Multiscale Analysis of Topographic Surface Roughness in the Midland Valley, Scotland. IEEE Transactions on Geoscience and Remote Sensing 49, 1220-1213. Herzfeld, U.C., Higginson, C.A., 1996. Automated geostatistical seafloor classification - Principles, parameters, feature vectors, and discrimination criteria. Computers and Geosciences, 22 (1), pp. 35-52. Lucieer, A., Stein, A., 2005. Texture-based landform segmentation of LiDAR imagery. International Journal of Applied Earth Observation and Geoinformation 6, 261-270. Ojala, T., Pietikäinen, M. & Mäenpää, T. 2002. "Multiresolution gray-scale and rotation invariant texture classification with local binary patterns", IEEE Transactions on Pattern Analysis and Machine Intelligence, vol. 24, no. 7, pp. 971-987. Smith, M.W. 2014. "Roughness in the Earth Sciences", Earth-Science Reviews, vol. 136, pp. 202-225. Trevisani, S., Cavalli, M. & Marchi, L. 2012. "Surface texture analysis of a high-resolution DTM: Interpreting an alpine basin", Geomorphology, vol. 161-162, pp. 26-39. Trevisani, S., Rocca, M. 2015. MAD: robust image texture analysis for applications in high resolution geomorphometry. Comput. Geosci. 81, 78-92. doi:10.1016/j.cageo.2015.04.003.

Microwave properties of sea ice in the marginal ice zone

NASA Technical Reports Server (NTRS)

Onstott, R. G.; Larson, R. W.

1986-01-01

Active microwave properties of summer sea ice were measured. Backscatter data were acquired at frequencies from 1 to 17 GHz, at angles from 0 to 70 deg from vertical, and with like and cross antenna polarizations. Results show that melt-water, snow thickness, snowpack morphology, snow surface roughness, ice surface roughness, and deformation characteristics are the fundamental scene parameters which govern the summer sea ice backscatter response. A thick, wet snow cover dominates the backscatter response and masks any ice sheet features below. However, snow and melt-water are not distributed uniformly and the stage of melt may also be quite variable. These nonuniformities related to ice type are not necessarily well understood and produce unique microwave signature characteristics.

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

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

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

2003-03-28

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

Laser induced nanostructures created from Au layer on polyhydroxybutyrate

NASA Astrophysics Data System (ADS)

Michaljaničová, I.; Slepička, P.; Juřík, P.; Švorčík, V.

2017-11-01

Nanostructures as well as composite materials expand the range of materials properties and allow use of these materials in new and highly specific applications. In this paper, we described laser modification of polyhydroxybutyrate films covered with thin gold layer, which led to the formation of various composite structures. The crucial for the composite structures creation was setting of appropriate laser parameters; 15 mJ cm-2 laser fluence and 6 000 pulses were recognized as the best. The morphology of structures was determined by the thickness of the Au layer. The most interesting formations, very porous with the biggest roughness, were observed after treatment of foils covered with 10 nm of Au. The morphology was observed by atomic force microscopy. The influence on roughness and the difference between projected area and surface area was also determined.

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

NASA Astrophysics Data System (ADS)

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

2017-12-01

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

An easy and environmentally-friendly approach to superamphiphobicity of aluminum surfaces

NASA Astrophysics Data System (ADS)

Deng, R.; Hu, Y. M.; Wang, L.; Li, Zh. H.; Shen, T.; Zhu, Y.; Xiang, J. Zh.

2017-04-01

Superamphiphobic Al surfaces were achieved via an easy and environmentally-friendly approach. Aqueous mixed solution of 0.7 M CuSO4 and 1 M NaCl was used to etch polished Al surfaces to fabricate a rough morphology distributed with microscale step-like pits. The uniformly distributed nanoscale petals covered on the microscale pits were obtained by subsequent 96 °C hot deionized water bathing for 13 min. Thus, the hierarchical micro/nanometer scale roughness was formed which provided the structural basic of superamphiphobic Al surfaces. By 1H, 1H, 2H, 2H-Perfluorodecyl-triethoxysilane (PFDTS) derivatization, desirable superamphiphobic Al surfaces were achieved with the highest static contact angles of 162° for water, 156° for peanut oil, respectively. Meanwhile, the sliding angles were lower than 10° for both water and peanut oil droplets. The as-prepared Al surfaces were investigated by field-emission scanning electron microscopy (FE-SEM), energy dispersive X-ray spectroscopy (EDS), X-ray photoelectron spectroscopy (XPS), and optical contact angle measurements. The FE-SEM images of as-prepared Al surfaces showed a hierarchical micro/nanometer scale morphology. XPS analyses demonstrated the PFDTS derivitization on Al surfaces. The superamphiphobic Al surfaces presented good mechanical durability and chemical stability which have a wide range of applications in fields such as self-cleaning, anti-icing, anti-corrosion, oil transportation, energy harvesting, microfluidics, and so forth. The approach reported in this paper may easily realize the industrial production of superamphiphobic Al surfaces owing to the advantage of facile, low cost and environmentally-friendly.

Effect of root planing on surface topography: an in-vivo randomized experimental trial.

PubMed

Rosales-Leal, J I; Flores, A B; Contreras, T; Bravo, M; Cabrerizo-Vílchez, M A; Mesa, F

2015-04-01

The root surface topography exerts a major influence on clinical attachment and bacterial recolonization after root planing. In-vitro topographic studies have yielded variable results, and clinical studies are necessary to compare root surface topography after planing with current ultrasonic devices and with traditional manual instrumentation. The aim of this study was to compare the topography of untreated single-rooted teeth planed in vivo with a curette, a piezoelectric ultrasonic (PU) scraper or a vertically oscillating ultrasonic (VOU) scraper. In a randomized experimental trial of 19 patients, 44 single-rooted teeth were randomly assigned to one of four groups for: no treatment; manual root planing with a curette; root planing with a PU scraper; or root planing with a VOU scraper. Post-treatment, the teeth were extracted and their topography was analyzed in 124 observations with white-light confocal microscopy, measuring the roughness parameters arithmetic average height, root-mean-square roughness, maximum height of peaks, maximum depth of valleys, absolute height, skewness and kurtosis. The roughness values arithmetic average height and root-mean-square roughness were similar after each treatment and lower than after no treatment ( p < 0.05). Absolute height was lower in the VOU group than in the untreated ( p = 0.0026) and PU (p = 0.045) groups. Surface morphology was similar after the three treatments and was less irregular than in the untreated group. Values for the remaining roughness parameters were similar among all treatment groups ( p > 0.05). Both ultrasonic devices reduce the roughness, producing a similar topography to that observed after manual instrumentation with a curette, to which they appear to represent a valid alternative. © 2014 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

A Synthesis and Comparison of Approaches for Quantifying Coral Reef Structure

NASA Astrophysics Data System (ADS)

Duvall, M. S.; Hench, J. L.

2016-02-01

The complex physical structures of coral reefs provide substrate for benthic organisms, surface area for material fluxes, and have been used as a predictor of reef-fish biomass and biodiversity. Coral reef topography has a first order effect on reef hydrodynamics by imposing drag forces and increasing momentum and scalar dispersion. Despite its importance, quantifying reef topography remains a challenge, as it is patchy and discontinuous while also varying over orders of magnitude in spatial scale. Previous studies have quantified reef structure using a range of 1D and 2D metrics that estimate vertical roughness, which is the departure from a flat geometric profile or surface. However, there is no general mathematical or conceptual framework by which to apply or compare these roughness metrics. While the specific calculations of different metrics vary, we propose that they can be classified into four categories based on: 1) vertical relief relative to a reference height; 2) gradients in vertical relief; 3) surface contour distance; or 4) variations in roughness with scale. We apply metrics from these four classes to idealized reef topography as well as natural reef topography data from Moorea, French Polynesia. Through the use of idealized profiles, we demonstrate the potential for reefs with different morphologies to possess the same value for some scale-dependent metrics (i.e. classes 1-3). Due to the superposition of variable-scale roughness elements in reef topography, we find that multi-scale metrics (i.e. class 4) can better characterize structural complexity by capturing surface roughness across a range of spatial scales. In particular, we provide evidence of the ability of 1D continuous wavelet transforms to detect changes in dominant roughness scales on idealized topography as well as within real reef systems.

Surface modification of Ni–Ti alloys for stent application after magnetoelectropolishing

PubMed Central

Musaramthota, Vishal; Munroe, Norman; Datye, Amit; Dua, Rupak; Haider, Waseem; McGoron, Anthony; Rokicki, Ryszard

2015-01-01

The constant demand for new implant materials and the multidisciplinary design approaches for stent applications have expanded vastly over the past decade. The biocompatibility of these implant materials is a function of their surface characteristics such as morphology, surface chemistry, roughness, surface charge and wettability. These surface characteristics can directly influence the material's corrosion resistance and biological processes such as endothelialization. Surface morphology affects the thermodynamic stability of passivating oxides, which renders corrosion resistance to passivating alloys. Magnetoelectropolishing (MEP) is known to alter the morphology and composition of surface films, which assist in improving corrosion resistance of Nitinol alloys. This work aims at analyzing the surface characteristics of MEP Nitinol alloys by scanning electron microscopy (SEM) and X-ray photoelectron spectroscopy (XPS). The wettability of the alloys was determined by contact angle measurements and the mechanical properties were assessed by Nanoindentation. Improved mechanical properties were observed with the addition of alloying elements. Cyclic potentiodynamic polarization tests were performed to determine the corrosion susceptibility. Further, the alloys were tested for their cytotoxicity and cellular growth with endothelial cells. Improved corrosion resistance and cellular viability were observed with MEP surface treated alloys. PMID:25746243

Cooling Performance of Additively Manufactured Microchannels and Film Cooling Holes

NASA Astrophysics Data System (ADS)

Stimpson, Curtis K.

Additive manufacturing (AM) enables fabrication of components that cannot be made with any other manufacturing method. Significant advances in metal-based AM systems have made this technology feasible for building production parts to be used use in commercial products. In particular, the gas turbine industry benefits from AM as a manufacturing technique especially for development of components subjected to high heat flux. It has been shown that the use of microchannels in high heat flux components can lead to more efficient cooling designs than those that presently exist. The current manufacturing methods have prevented the use of microchannels in such parts, but AM now makes them manufacturable. However, before such designs can become a reality, much research must be done to characterize impacts on flow and heat transfer of AM parts. The current study considers the effect on flow and heat transfer through turbine cooling features made with AM. Specifically, the performance of microchannels and film cooling holes made with laser powder bed fusion (L-PBF) is assessed. A number of test coupons containing microchannels were built from high temperature alloy powders on a commercially available L-PBF machine. Pressure drop and heat transfer experiments characterized the flow losses and convective heat transfer of air passing through the channels at various Reynolds numbers and Mach numbers. The roughness of the channels' surfaces was characterized in terms of statistical roughness parameters; the morphology of the roughness was examined qualitatively. Magnitude and morphology of surface roughness found on AM parts is unlike any form of roughness seen in the literature. It was found that the high levels of roughness on AM surfaces result in markedly augmented pressure loss and heat transfer at all Reynolds numbers, and conventional flow and heat transfer correlations produce erroneous estimates. The physical roughness measurements made in this study were correlated to flow and heat transfer measurements to generate a predictive model for flow through AM microchannels. The flow compressibility was also found to play a significant role in flow loss through these channels. Overall effectiveness of film cooling combined with the internal microchannel flow was examined in a conjugate experimental setup. The validity of the experimental conditions was established by matching important dimensionless parameters of the experimental setup to common values found in turbine engines. These results showed that the roughness in the film cooling holes produced higher in-hole convection than those made with current manufacturing methods. The roughness in the holes also repressed the film performance. However, high relative roughness was shown to minimize the impact of coolant feed direction on the film effectiveness of the AM holes.

MC3T3-E1 cell response to stainless steel 316L with different surface treatments.

PubMed

Zhang, Hongyu; Han, Jianmin; Sun, Yulong; Huang, Yongling; Zhou, Ming

2015-11-01

In the present study, stainless steel 316L samples with polishing, aluminum oxide blasting, and hydroxyapatite (HA) coating were prepared and characterized through a scanning electron microscope (SEM), optical interferometer (surface roughness, Sq), contact angle, surface composition and phase composition analyses. Osteoblast-like MC3T3-E1 cell adhesion on the samples was investigated by cell morphology using a SEM (4h, 1d, 3d, 7d), and cell proliferation was assessed by MTT method at 1d, 3d, and 7d. In addition, adsorption of bovine serum albumin on the samples was evaluated at 1h. The polished sample was smooth (Sq: 1.8nm), and the blasted and HA coated samples were much rougher (Sq: 3.2μm and 7.8μm). Within 1d of incubation, the HA coated samples showed the best cell morphology (e.g., flattened shape and complete spread), but there was no significant difference after 3d and 7d of incubation for all the samples. The absorbance value for the HA coated samples was the highest after 1d and 3d of incubation, indicating better cell viability. However, it reduced to the lowest value at 7d. Protein adsorption on the HA coated samples was the highest at 1h. The results indicate that rough stainless steel surface improves cell adhesion and morphology, and HA coating contributes to superior cell adhesion, but inhibits cell proliferation. Copyright © 2015. Published by Elsevier B.V.

Optimization of the buffer surface of CoFeB/MgO/CoFeB-based magnetic tunnel junctions by ion beam milling

NASA Astrophysics Data System (ADS)

Martins, L.; Ventura, J.; Ferreira, R.; Freitas, P. P.

2017-12-01

Due to their high tunnel magnetoresistance (TMR) ratios at room temperature, magnetic tunnel junctions (MTJs) with a crystalline MgO insulating barrier and CoFeB ferromagnetic (FM) layers are the best candidates for novel magnetic memory applications. To overcome impedance matching problems in electronic circuits, the MgO barrier must have an ultra-low thickness (∼1 nm). Therefore, it is mandatory to optimize the MTJ fabrication process, in order to prevent relevant defects in the MgO barrier that could affect the magnetic and electrical MTJ properties. Here, a smoothing process aiming to decrease the roughness of the buffer surface before the deposition of the full MTJ stack is proposed. An ion beam milling process was used to etch the surface of an MTJ buffer structure with a Ru top layer. The morphologic results prove an effective decrease of the Ru surface roughness with the etching time. The electrical and magnetic results obtained for MTJs with smoothed buffer structures show a direct influence of the buffer roughness and coupling field on the improvement of the TMR ratio.

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.

The effect of self-assembled monolayers on graphene conductivity and morphology

NASA Astrophysics Data System (ADS)

Moore, T. L.; Chen, J. H.; Riddick, B.; Williams, E. D.

2009-03-01

Graphene transport properties are limited by charge defects in SiO2, and by large charge density due to strong interaction with SiC. To modify these effects we have treated 300 nm SiO2 with tricholosilanes with different termination groups including pure and fluoro and amino-terminated hydrocarbons for use as substrates for mechanical exfoliation of graphene. XPS measurements verify the presence of the expected termination groups. AFM measurements reveal modified monolayer roughness and correlation lengths; for a fluorinated carbon chain the RMS roughness is 0.266 ± 0.017 nm and the correlation length is 10.2 ± 0.7 nm compared to 0.187 ± 0.011 nm and 19.8 ± 2.5 nm for SiO2. Surface free energies of the monolayers and the SiO2 blank have been computed from static contact angle measurements and all decrease the SiO2 surface free energy; for the fluorinated carbon chain monolayer a decrease of 20 mJ/m^2 from SiO2. We will discuss the ease of exfoliation, and the morphology and conductivity of graphene on these monolayers.

Effects of rf power on chemical composition and surface roughness of glow discharge polymer films

NASA Astrophysics Data System (ADS)

Zhang, Ling; He, Xiaoshan; Chen, Guo; Wang, Tao; Tang, Yongjian; He, Zhibing

2016-03-01

The glow discharge polymer (GDP) films for laser fusion targets were successfully fabricated by plasma enhanced chemical vapor deposition (PECVD) at different radio frequency (rf) powers. The films were deposited using trans-2-butene (T2B) mixed with hydrogen as gas sources. The composition and state of plasma were diagnosed by quadrupole mass spectrometer (QMS) and Langmuir probe during the deposition process. The composition, surface morphology and roughness were investigated by Fourier transform infrared spectroscopy (FTIR), scanning electron microscope (SEM) and white-light interferometer (WLI), respectively. Based on these observation and analyses, the growth mechanism of defects in GDP films were studied. The results show that, at low rf power, there is a larger probability for secondary polymerization and formation of multi-carbon C-H species in the plasma. In this case, the surface of GDP film turns to be cauliflower-like. With the increase of rf power, the degree of ionization is high, the relative concentration of smaller-mass hydrocarbon species increases, while the relative concentration of larger-mass hydrocarbon species decreases. At higher rf power, the energy of smaller-mass species are high and the etching effects are strong correspondingly. The GDP film's surface roughness shows a trend of decrease firstly and then increase with the increasing rf power. At rf power of 30 W, the surface root-mean-square roughness (Rq) drops to the lowest value of 12.8 nm, and no ;void; defect was observed.

Electrochemical behavior and biological response of Mesenchymal Stem Cells on cp-Ti after N-ions implantation

NASA Astrophysics Data System (ADS)

Rizwan, M.; Ahmad, A.; Deen, K. M.; Haider, W.

2014-11-01

Titanium and its alloys are most widely used as implant materials due to their excellent biocompatibility, mechanical properties and chemical stability. In this study Nitrogen ions of known dosage were implanted over cp-Ti by Pelletron accelerator with beam energy of 0.25 MeV.The atomic force microscopy of bare and nitrogen implanted specimens confirmed increase in surface roughness with increase in nitrogen ions concentration. X-ray diffraction patterns of ions implanted surfaces validated the formation of TiN0.3 and Ti3N2-xnitride phases. The tendency to form passive film and electrochemical behavior of these surfaces in ringer lactate (RL) solution was evaluated by Potentiodynamic polarization and electrochemical impedance spectroscopy respectively. It is proved that nitrogen ions implantation was beneficial to reduce corrosion rate and stabilizing passive film by increasing charge transfer resistance in RL. It was concluded that morphology and proliferation of Mesenchymal Stem Cells on nitrogen ions implanted surfaces strongly depends on surface roughness and nitride phases.

The effect of polar end of long-chain fluorocarbon oligomers in promoting the superamphiphobic property over multi-scale rough Al alloy surfaces

NASA Astrophysics Data System (ADS)

Saifaldeen, Zubayda S.; Khedir, Khedir R.; Camci, Merve T.; Ucar, Ahmet; Suzer, Sefik; Karabacak, Tansel

2016-08-01

Rough structures with re-entrant property and their subsequent surface energy reduction with long-chain fluorocarbon oligomers are both critical in developing superamphiphobic (SAP, i.e. both super hydrophobic and superoleophobic) surfaces. However, morphology of the low-surface energy layer on a rough re-entrant substrate can strongly depend on the fluorocarbon oligomers used. In this study, the effect of polar end of different kinds of long-chain fluorocarbon oligomers in promoting a self-assembled monolayer with close packed molecules and robust adhesion on multi-scale rough Al alloy surfaces was investigated. Hierarchical Al alloy surfaces with microgrooves and nanograss structures were developed by a simple combination of one-directional mechanical sanding and post treatment in boiling de-ionized water (DIW). Three types of long-chain fluorocarbon oligomers of 1H, 1H, 2H, 2H-perfluorodecyltriethoxysilane (PFDTS), 1H, 1H, 2H, 2H-perfluorodecyltrichlorosilane (PFDCS), and perfluorooctanoic acid (PFOA) were chemically vaporized onto these rough Al alloy surfaces. The PFDCS exhibited the lowest surface free energy of less than 10 mN/m. The contact angle and sliding angle measurements for water, ethylene glycol, and peanut oil verified the SAP property of hierarchical rough Al alloy surfaces treated with alkylsilane oligomers (PFDTS, PFDCS). However, the hierarchical surfaces treated with fluorocarbon oligomer with polar acidic tail (PFOA) showed highly amphiphobic properties but could not reach the threshold for SAP. Chemical stability of the hierarchical Al alloy surfaces treated with the fluorocarbon oligomers was tested under the harsh conditions of ultra-sonication in acetone and annealing at high temperature after different treatment times. Contact angle measurements revealed the robustness of the alkylsilane oligomers and deterioration of the PFOA coating particularly for low surface tension liquids. The robust adhesion and close-packing of the alkylsilane molecules as well as their vertical orientation with exposure of more CF3 groups instead of CF2 groups due to the polar silane-based tail are believed to be the main reasons behind their improved chemical stability. The selection of fluorocarbon oligomer with proper polar tail which can promote a self-assembled monolayer with close-packed molecules could make it possible for utilizing shorter fluorocarbon oligomers, which is environmentally favorable, to develop high surface energy materials with SAP properties.

The balance between keystone clustering and bed roughness in experimental step-pool stabilization

NASA Astrophysics Data System (ADS)

Johnson, J. P.

2016-12-01

Predicting how mountain channels will respond to environmental perturbations such as floods requires an improved quantitative understanding of morphodynamic feedbacks among bed topography, surface grain size and sediment sorting. In boulder-rich gravel streams, transport and sorting often lead to the development of step pool morphologies, which are expressed both in bed topography and coarse grain clustering. Bed stability is difficult to measure, and is sometimes inferred from the presence of step pools. I use scaled flume experiments to explore feedbacks among surface grain sizes, coarse grain clustering, bed roughness and hydraulic roughness during progressive bed stabilization and over a range of sediment transport rates. While grain clusters are sometimes identified by subjective interpretation, I quantify the degree of coarse surface grain clustering using spatial statistics, including a novel normalization of Ripley's K function. This approach is objective and provides information on the strength of clustering over a range of length scales. Flume experiments start with an initial bed surface with a broad grain size distribution and spatially random positions. Flow causes the bed surface to progressively stabilize in response to erosion, surface coarsening, roughening and grain reorganization. At 95% confidence, many but not all beds stabilized with coarse grains becoming more clustered than complete spatial randomness (CSR). I observe a tradeoff between topographic roughness and clustering. Beds that stabilized with higher degrees of coarse-grain clustering were topographically smoother, and vice-versa. Initial conditions influenced the degree of clustering at stability: Beds that happened to have fewer initial coarse grains had more coarse grain reorganization during stabilization, leading to more clustering. Finally, regressions demonstrate that clustering statistics actually predict hydraulic roughness significantly better than does D84 (the size at which 84% of grains are smaller). In the experimental data, the spatial organization of surface grains is a stronger control on flow characteristics than the size of surface grains.

Comparison of Galunggung1982-83 and Eyjafjalla-2010 Eruptions: definition of eruption dynamics from 3D Ash Surface Morphology

NASA Astrophysics Data System (ADS)

Aydar, E.; Höskuldsson, A.; Ersoy, O.; Gourgaud, A.

2012-04-01

We consider that all works, concepts on aviation safety, security codes, establishment of warning systems etc begin in 1982, when two commercial jumbo jets en route to Australia across Indonesia suffered loss of engine thrust from ingesting volcanic ash from the erupting Galunggung Volcano, Java, and descended more than 20,000 ft before the engines could be restarted (Casadevall, 1991). It is not the only incident of this kind but this Galunggung eruption had a pionner character attracting attention on aviation safety against volcanic eruptions in international community. As the needs for precautions on aviation safety against volcanic ash encounters began with Galunggung 1982 eruption and as we all concerned by the measures taken by ICAO due to Eyjafjallajökull-2010 eruption, we aimed to investigate this last huge airspace perturbing eruption and compare the volcanic ashes produced by those two eruptions. Volcanic ash characterization should be most important parameter to understand how the eruption concerned unrolled. Galunggung 1982-83 eruption was exceptionally long, lasting about nine months between 5 April 1982-8 January 1983). During this well known eruption, the composition of the erupted magma evolved from andesite (58% SiO2) to Mg-rich basalt (47% SiO2), while the style of the eruption changed drastically through time (Katili and Sudrdajat, 1984; Sudrajat and Tilling, 1984; Gourgaud et al., 1989 gourgaud etal 2000). Paralel to chemical changes and water consumption, eruption dynamic was also changed and occured in three eruption phases with different eruptive styles as an initial Vulcanian phase (5 April-13 May), a phreatomagmatic phase (17 May-28 October) and a Strombolian phase (3 November-8 January), have been recognized (Katili and Sudradjat,1984). We examined the surficial morphological features of proximal tephra collected from Galunggung and Eyjafjalla volcanoes. Surface texture and morphology of volcanic ash particles change according to various fragmentation mechanisms. Several common types of ashes produced during phreatomagmatic fragmentation process bear blocky-equant, mosslike, plate-like and drop or spherical shapes, besides, magmatic fragmentation leads to the formation of vesiculated fragments. We applied some quantitative statistical parameters for surface descriptors of volcanic ashes such as "Average roughness of profile (Ra), Maximum valley height of roughness profile (Rv), profile irregularities of roughness profile, Surface Area (SA), Volume (V), Fractal Dimension of Roughness (DAS)". We compared quantitative morphological data acquired from both eruptions. The grain size distribution of Eyjafjalla-2010 eruption, ash surface morphology, tephras types and textural parameters exhibit that magma input was important during the first phase (14-16 April) than following days. First phase ashes have either tubular vesicles as classically known for plinian deposits or curviplanar cut vesicles and some brittle fracturations, characteristics of phreatomagmatism. Interestingly, coarse fragmentation happened after the first phase. There is great similarities between two eruptions, but in reverse sens that in Galunggung, the eruption started with vulcanian style then phreatomatism and lasted with strombolian activity. Besides in Eyjafjalla-2010, eruptive phase started with basaltic activities at the North, then phreatomagmatism and toward the end a slight vulcanian style happened.

Effect of strain on the electron effective mobility in biaxially strained silicon inversion layers: An experimental and theoretical analysis via atomic force microscopy measurements and Kubo-Greenwood mobility calculations

NASA Astrophysics Data System (ADS)

Bonno, Olivier; Barraud, Sylvain; Mariolle, Denis; Andrieu, François

2008-03-01

Recently, in order to explain the long-channel electron effective mobility at a high sheet carrier density in strained silicon channel transistors, it has been suggested by [M. V. Fischetti, F. Gamiz, and W. Hansch, J. Appl. Phys. 92, 7230 (2002)] that biaxial tensile strain should smooth the Si/SiO2 interface. To address this topic, the roughness properties of biaxial strained silicon-on-insulator (s-SOI) films are investigated by means of atomic force microscopy. Through in-depth statistical analysis of the digitalized surface profiles, the roughness parameters are extracted for unstrained and strained SOI films, with 0.8% biaxial tensile strain. Especially, it is found that strain significantly reduces the roughness amplitude. Then, mobility calculations in SOI and s-SOI inversion layers are performed in the framework of the Kubo-Greenwood formalism. The model accounts for the main scattering mechanisms that are dominant in the high electron density range, namely phonon and surface roughness. Special attention has been paid to the modeling of the latter by accounting for all the contributions of the potential which arise from the deformed rough interface, and by using a multisubband wavelength-dependent screening model. This model is then applied to study the influence of the surface morphology on the mobility in s-SOI inversion layers. In this context, the mobility gain between s-SOI and unstrained SOI layers is found to agree significantly better with experimental data if the strain-induced decrease of the roughness amplitude is taken into account.

Smoothing of Fault Slip Surfaces by Scale Invariant Wear

NASA Astrophysics Data System (ADS)

Dascher-Cousineau, K.; Kirkpatrick, J. D.

2017-12-01

Fault slip surface roughness plays a determining role in the overall strength, friction, and dynamic behavior of fault systems. Previous wear models and field observations suggest that roughness decreases with increasing displacement. However, measurements have yet to isolate the effect of displacement from other possible controls, such as lithology or tectonic setting. In an effort to understand the effect of displacement, we present comprehensive qualitative and quantitative description of the evolution of fault slip surfaces in and around the San-Rafael Desert, S.E. Utah, United States. In the study area, faults accommodated regional extension at shallow (1 to 3 km) depth and are hosted in the massive, well-sorted, high-porosity Navajo and Entrada sandstones. Existing displacement profiles along with tight displacement controls readily measureable in the field, combined with uniform lithology and tectonic history, allowed us to isolate for the effect of displacement during the embryonic stages of faulting (0 to 60 m in displacement). Our field observations indicate a clear compositional and morphological progression from isolated joints or deformation bands towards smooth, continuous, and mirror-like fault slip surfaces with increasing displacement. We scanned pristine slip surfaces with a white light interferometer, a laser scanner, and a ground-based LiDAR. We produce and analyses more than 120 individual scans of fault slip surfaces. Results for the surfaces with the best displacement constraints indicate that roughness as defined by the power spectral density at any given length scale decreases with displacement according to a power law with an exponent of -1. Roughness measurements associated with only maximum constraints on displacements corroborate this result. Moreover, maximum roughness for any given fault is bounded by a primordial roughness corresponding to that of joint surfaces and deformation band edges. Building upon these results, we propose a multi-scale wear model to explain the evolution of faults with displacement. We suggest that together, asperity failure as a scale invariant process, and the stochastic strength of host rocks are consistent with qualitative and quantitative observational constraints made in this study.

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

NASA Astrophysics Data System (ADS)

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

2018-01-01

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

Hexagonally ordered nanodots: Result of substrate rotation during oblique incidence low energy IBS

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

Chowdhury, Debasree, E-mail: debasree.chowdhury@saha.ac.in; Ghose, Debabrata, E-mail: debasree.chowdhury@saha.ac.in

The anisotropic regular patterns are often results during oblique incidence ion beam sputtering (IBS). Simultaneous substrate rotation (SR) during IBS can suppress surface roughening and removes anisotropic nature of surface pattern. Here, the evolution of Si surface morphology as result of with and without SR is studied during oblique incidence low energy Ar{sup +} sputtering. Resultant topography shows smooth surface to hexagonally ordered nanodots at different rotating conditions. Interestingly, surface roughness exhibits non-monotonic dependence on rotation frequency. The underlying mechanism for dot formation can be described within the framework of isotropic DKS equation.

Anisotropic Strain Relaxation of Graphene by Corrugation on Copper Crystal Surfaces.

PubMed

Deng, Bing; Wu, Juanxia; Zhang, Shishu; Qi, Yue; Zheng, Liming; Yang, Hao; Tang, Jilin; Tong, Lianming; Zhang, Jin; Liu, Zhongfan; Peng, Hailin

2018-05-01

Corrugation is a ubiquitous phenomenon for graphene grown on metal substrates by chemical vapor deposition, which greatly affects the electrical, mechanical, and chemical properties. Recent years have witnessed great progress in controlled growth of large graphene single crystals; however, the issue of surface roughness is far from being addressed. Here, the corrugation at the interface of copper (Cu) and graphene, including Cu step bunches (CuSB) and graphene wrinkles, are investigated and ascribed to the anisotropic strain relaxation. It is found that the corrugation is strongly dependent on Cu crystallographic orientations, specifically, the packed density and anisotropic atomic configuration. Dense Cu step bunches are prone to form on loose packed faces due to the instability of surface dynamics. On an anisotropic Cu crystal surface, Cu step bunches and graphene wrinkles are formed in two perpendicular directions to release the anisotropic interfacial stress, as revealed by morphology imaging and vibrational analysis. Cu(111) is a suitable crystal face for growth of ultraflat graphene with roughness as low as 0.20 nm. It is believed the findings will contribute to clarifying the interplay between graphene and Cu crystal faces, and reducing surface roughness of graphene by engineering the crystallographic orientation of Cu substrates. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Direct morphological comparison of vacuum plasma sprayed and detonation gun sprayed hydroxyapatite coatings for orthopaedic applications.

PubMed

Gledhill, H C; Turner, I G; Doyle, C

1999-02-01

Hydroxyapatite coatings on titanium substrates were produced using two thermal spray techniques vacuum plasma spraying and detonation gun spraying. X-ray diffraction was used to compare crystallinity and residual stresses in the coatings. Porosity was measured using optical microscopy in conjunction with an image analysis system. Scanning electron microscopy and surface roughness measurements were used to characterise the surface morphologies of the coatings. The vacuum plasma sprayed coatings were found to have a lower residual stress, a higher crystallinity and a higher level of porosity than the detonation gun coatings. It is concluded that consideration needs to be given to the significance of such variations within the clinical context.

Wear behavior of pressable lithium disilicate glass ceramic.

PubMed

Peng, Zhongxiao; Izzat Abdul Rahman, Muhammad; Zhang, Yu; Yin, Ling

2016-07-01

This article reports effects of surface preparation and contact loads on abrasive wear properties of highly aesthetic and high-strength pressable lithium disilicate glass-ceramics (LDGC). Abrasive wear testing was performed using a pin-on-disk device in which LDGC disks prepared with different surface finishes were against alumina pins at different contact loads. Coefficients of friction and wear volumes were measured as functions of initial surface finishes and contact loads. Wear-induced surface morphology changes in both LDGC disks and alumina pins were characterized using three-dimensional laser scanning microscopy, scanning electron microscopy, and energy dispersive X-ray spectroscopy. The results show that initial surface finishes of LDGC specimens and contact loads significantly affected the friction coefficients, wear volumes and wear-induced surface roughness changes of the material. Both wear volumes and friction coefficients of LDGC increased as the load increased while surface roughness effects were complicated. For rough LDGC surfaces, three-body wear was dominant while for fine LDGC surfaces, two-body abrasive wear played a key role. Delamination, plastic deformation, and brittle fracture were observed on worn LDGC surfaces. The adhesion of LDGC matrix materials to alumina pins was also discovered. This research has advanced our understanding of the abrasive wear behavior of LDGC and will provide guidelines for better utilization and preparation of the material for long-term success in dental restorations. © 2015 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 104B: 968-978, 2016. © 2015 Wiley Periodicals, Inc.

Morphology and structure evolution of Cu(In,Ga)S{sub 2} films deposited by reactive magnetron co-sputtering with electron cyclotron resonance plasma assistance

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

Nie, Man, E-mail: man.nie@helmholtz-berlin.de; Ellmer, Klaus

2014-02-28

Cu(In,Ga)S{sub 2} (CIGS) films were deposited on Mo coated soda lime glass substrates using an electron cyclotron resonance plasma enhanced one-step reactive magnetron co-sputtering process (ECR-RMS). The crystalline quality and the morphology of the Cu(In,Ga)S{sub 2} films were investigated by X-ray diffraction, atomic force microscopy, scanning electron microscopy, and X-ray fluorescence. We also compared these CIGS films with films previously prepared without ECR assistance and find that the crystallinity of the CIGS films is correlated with the roughness evolution during deposition. Atomic force microscopy was used to measure the surface topography and to derive one-dimensional power spectral densities (1DPSD). Allmore » 1DPSD spectra of CIGS films exhibit no characteristic peak which is typical for the scaling of a self-affine surface. The growth exponent β, characterizing the roughness R{sub q} evolution during the film growth as R{sub q} ∼ d{sup β}, changes with film thickness. The root-mean-square roughness at low temperatures increases only slightly with a growth exponent β = 0.013 in the initial growth stage, while R{sub q} increases with a much higher exponent β = 0.584 when the film thickness is larger than about 270 nm. Additionally, we found that the H{sub 2}S content of the sputtering atmosphere and the Cu- to-(In + Ga) ratio has a strong influence of the morphology of the CIGS films in this one-step ECR-RMS process.« less

Slip as the basic mechanism for formation of deformation relief structural elements

NASA Astrophysics Data System (ADS)

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

2017-07-01

The experimental results of investigation of the nickel single crystal surface morphology after compression deformation are presented. The quasi-periodic character of the deformation profile, common for shear deformation of different types of relief structural elements, is found. It is demonstrated that the morphological manifestation of these structural elements is determined by local shear systems along octahedral planes. The regularities of the deformation structure in these regions defining the material extrusion and intrusion regions and the specific features of disorientation accumulation are established. If reorientation of local regions takes part in the relief element formation, along with octahedral slip, much stronger growth of the surface area is observed. The possibility of application of two-dimensional and three-dimensional surface roughness parameters for description of deformation relief is considered.

Microstructural, nanomechanical, and microtribological properties of Pb thin films prepared by pulsed laser deposition and thermal evaporation techniques

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

Broitman, Esteban, E-mail: esbro@ifm.liu.se; Flores-Ruiz, Francisco J.; Di Giulio, Massimo

2016-03-15

In this work, the authors compare the morphological, structural, nanomechanical, and microtribological properties of Pb films deposited by thermal evaporation (TE) and pulsed laser deposition (PLD) techniques onto Si (111) substrates. Films were investigated by scanning electron microscopy, surface probe microscopy, and x-ray diffraction in θ-2θ geometry to determine their morphology, root-mean-square (RMS) roughness, and microstructure, respectively. TE films showed a percolated morphology with densely packed fibrous grains while PLD films had a granular morphology with a columnar and tightly packed structure in accordance with the zone growth model of Thornton. Moreover, PLD films presented a more polycrystalline structure withmore » respect to TE films, with RMS roughness of 14 and 10 nm, respectively. Hardness and elastic modulus vary from 2.1 to 0.8 GPa and from 14 to 10 GPa for PLD and TE films, respectively. A reciprocal friction test has shown that PLD films have lower friction coefficient and wear rate than TE films. Our study has demonstrated for first time that, at the microscale, Pb films do not show the same simple lubricious properties measured at the macroscale.« less

Surface topography and chemistry shape cellular behavior on wide band-gap semiconductors.

PubMed

Bain, Lauren E; Collazo, Ramon; Hsu, Shu-Han; Latham, Nicole Pfiester; Manfra, Michael J; Ivanisevic, Albena

2014-06-01

The chemical stability and electrical properties of gallium nitride make it a promising material for the development of biocompatible electronics, a range of devices including biosensors as well as interfaces for probing and controlling cellular growth and signaling. To improve the interface formed between the probe material and the cell or biosystem, surface topography and chemistry can be applied to modify the ways in which the device interacts with its environment. PC12 cells are cultured on as-grown planar, unidirectionally polished, etched nanoporous and nanowire GaN surfaces with and without a physisorbed peptide sequence that promotes cell adhesion. While cells demonstrate preferential adhesion to roughened surfaces over as-grown flat surfaces, the topography of that roughness also influences the morphology of cellular adhesion and differentiation in neurotypic cells. Addition of the peptide sequence generally contributes further to cellular adhesion and promotes development of stereotypic long, thin neurite outgrowths over alternate morphologies. The dependence of cell behavior on both the topographic morphology and surface chemistry is thus demonstrated, providing further evidence for the importance of surface modification for modulating bio-inorganic interfaces. Copyright © 2014 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

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

NASA Astrophysics Data System (ADS)

Yoshida, Ryoma; Tosaka, Aki; Shigeta, Yukichi

2018-05-01

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

Roughness and pH changes of enamel surface induced by soft drinks in vitro-applications of stylus profilometry, focus variation 3D scanning microscopy and micro pH sensor.

PubMed

Fujii, Mie; Kitasako, Yuichi; Sadr, Alireza; Tagami, Junji

2011-01-01

This study aimed to evaluate enamel surface roughness (Ra) and pH before and after erosion by soft drinks. Enamel was exposed to a soft drink (cola, orange juice or green tea) for 1, 5 or 60 min; Ra was measured using contact-stylus surface profilometry (SSP) and non-contact focus variation 3D microscope (FVM). Surface pH was measured using a micro pH sensor. Data were analyzed at significance level of alpha=0.05. There was a significant correlation in Ra between SSP and FVM. FVM images showed no changes in the surface morphology after various periods of exposure to green tea. Unlike cola and orange juice, exposure to green tea did not significantly affect Ra or pH. A significant correlation was observed between surface pH and Ra change after exposure to the drinks. Optical surface analysis and micro pH sensor may be useful tools for non-damaging, quantitative assessment of soft drinks erosion on enamel.

Effect of fabrication parameters on morphological and optical properties of highly doped p-porous silicon

NASA Astrophysics Data System (ADS)

Zare, Maryam; Shokrollahi, Abbas; Seraji, Faramarz E.

2011-09-01

Porous silicon (PS) layers were fabricated by anodization of low resistive (highly doped) p-type silicon in HF/ethanol solution, by varying current density, etching time and HF concentration. Atomic force microscopy (AFM) and field emission scanning electron microscope (FESEM) analyses were used to investigate the physical properties and reflection spectrum was used to investigate the optical behavior of PS layers in different fabrication conditions. Vertically aligned mesoporous morphology is observed in fabricated films and with HF concentration higher than 20%. The dependence of porosity, layer thickness and rms roughness of the PS layer on current density, etching time and composition of electrolyte is also observed in obtained results. Correlation between reflectivity and fabrication parameters was also explored. Thermal oxidation was performed on some mesoporous layers that resulted in changes of surface roughness, mean height and reflectivity of the layers.

An evaluation of two types of nickel-titanium wires in terms of micromorphology and nickel ions' release following oral environment exposure.

PubMed

Ghazal, Abdul Razzak A; Hajeer, Mohammad Y; Al-Sabbagh, Rabab; Alghoraibi, Ibrahim; Aldiry, Ahmad

2015-01-01

This study aimed to compare superelastic and heat-activated nickel-titanium orthodontic wires' surface morphology and potential release of nickel ions following exposure to oral environment conditions. Twenty-four 20-mm-length distal cuts of superelastic (NiTi Force I®) and 24 20-mm-length distal cuts of heat-activated (Therma-Ti Lite®) nickel-titanium wires (American Orthodontics, Sheboygan, WI, USA) were divided into two equal groups: 12 wire segments left unused and 12 segments passively exposed to oral environment for 1 month. Scanning electron microscopy and atomic force microscopy were used to analyze surface morphology of the wires which were then immersed in artificial saliva for 1 month to determine potential nickel ions' release by means of atomic absorption spectrophotometer. Heat-activated nickel-titanium (NiTi) wires were rougher than superelastic wires, and both types of wires released almost the same amount of Ni ions. After clinical exposure, more surface roughness was recorded for superelastic NiTi wires and heat-activated NiTi wires. However, retrieved superelastic NiTi wires released less Ni ions in artificial saliva after clinical exposure, and the same result was recorded regarding heat-activated wires. Both types of NiTi wires were obviously affected by oral environment conditions; their surface roughness significantly increased while the amount of the released Ni ions significantly declined.

Improvement of PET surface hydrophilicity and roughness through blending

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

Kolahchi, Ahmad Rezaei; Ajji, Abdellah; Carreau, Pierre J.

Controlling the adhesion of the polymer surface is a key issue in surface science, since polymers have been a commonly used material for many years. The surface modification in this study includes two different aspects. One is to enhance the hydrophilicity and the other is to create the roughness on the PET film surface. In this study we developed a novel and simple approach to modify polyethylene terephthalate (PET) film surface through polymer blending in twin-screw extruder. One example described in the study uses polyethylene glycol (PEG) in polyethylene terephthalate (PET) host to modify a PET film surface. Low contentmore » of polystyrene (PS) as a third component was used in the system to increase the rate of migration of PEG to the surface of the film. Surface enrichment of PEG was observed at the polymer/air interface of the polymer film containing PET-PEG-PS whereas for the PET-PEG binary blend more PEG was distributed within the bulk of the sample. Furthermore, a novel method to create roughness at the PET film surface was proposed. In order to roughen the surface of PET film, a small amount of PKHH phenoxy resin to change PS/PET interfacial tension was used. The compatibility effect of PKHH causes the formation of smaller PS droplets, which were able to migrate more easily through PET matrix. Consequently, resulting in a locally elevated concentration of PS near the surface of the film. The local concentration of PS eventually reached a level where a co-continuous morphology occurred, resulting in theinstabilities on the surface of the film.« less

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

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

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

Self-assembly of fatty acids on hydroxylated Al surface and effects of their stability on wettability and nanoscale organization.

PubMed

Liascukiene, Irma; Steffenhagen, Marie; Asadauskas, Svajus J; Lambert, Jean-François; Landoulsi, Jessem

2014-05-27

The self-assembly of fatty acids (FA) on the surfaces of inorganic materials is a relevant way to control their wetting properties. While the mechanism of adsorption on model flat substrate is well described in the literature, interfacial processes remain poorly documented on nanostructured surfaces. In this study, we report the self-assembly of a variety of FA on a hydroxylated Al surface which exhibits a random nanoscale organization. Our results revealed a peculiar fingerprint due to the FA self-assembly which consists in the formation of aligned nanopatterns in a state of hierarchical nanostructuration, regardless of the molecular structure of the FA (chain length, level of unsaturation). After a significant removal of adsorbed FA using UV/O3 treatment, a complete wetting was reached, and a noticeable disturbance of the surface morphology was observed, evidencing the pivotal role of FA molecules to maintain these nanostructures. The origin of wetting properties was investigated prior to and after conditioning of FA-modified samples taking into account key parameters, namely the surface roughness and its composition. For this purpose, the Wenzel roughness, defined as the third moment of power spectral density, was used, as it is sensitive to high spatial frequency and thus to the obtained hierarchical level of nanostructuration. Our results revealed that no correlation can be made between water contact angles (θ(w)) and the Wenzel roughness. By contrast, θ(w) strongly increased with the amount of -CHx- groups exhibited by adsorbed FA. These findings suggest that the main origin of hydrophobization is the presence of self-assembled molecules and that the surface roughness has only a small contribution to the wettability.

Effect of 100 MeV Ag+7 ion irradiation on the bulk and surface magnetic properties of Co-Fe-Si thin films

NASA Astrophysics Data System (ADS)

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

2014-12-01

Thin films of Co-Fe-Si were vacuum evaporated on pre-cleaned float glass substrates employing thermal evaporation. The films were subsequently irradiated with 100 MeV Ag+7 ions at fluences of 1×1011, 1×1012 and 1×1013 ions/cm2. The pristine and irradiated samples were subjected to surface analysis using Atomic Force Microscopy (AFM), Vibrating Sample Magnetometry (VSM) and Magneto Optic Kerr Effect (MOKE) measurements. The as deposited film has a root mean square roughness (Rq) of 8.9 nm and an average roughness of (Ra) 5.6 nm. Irradiation of the as deposited films with 100 MeV Ag7+ ions modifies the surface morphology. Irradiating with ions at fluences of 1×1011 ions/cm2 smoothens the mesoscopic hill-like structures, and then, at 1×1012 ions/cm2 new surface structures are created. When the fluence is further increased to 1×1013 ions/cm2 an increase in the surface roughness is observed. The MOKE loop of as prepared film indicated a squareness ratio of 0.62. As the film is irradiated with fluences of 1×1011 ions/cm2, 1×1012 ions/cm2 and 1×1013 ions/cm2 the squareness ratio changes to 0.76, 0.8 and 0.86 respectively. This enhancement in squareness ratio towards 1 is a typical feature when the exchange interaction starts to dominates the inherent anisotropies in the system. The variation in surface magnetisation is explained based on the variations in surface roughness with swift heavy ion (SHI) irradiation.

Morphology and texture of particles along the Spirit rover traverse from sol 450 to sol 745

NASA Astrophysics Data System (ADS)

Yingst, R. A.; Crumpler, L.; Farrand, W. H.; Li, R.; Cabrol, N. A.; Neakrase, L. D.

2008-12-01

We quantified and classified the shape, roundness, size, and texture of 935 loose surface particles along the Spirit rover traverse from sols 450-745 to assess origin, transport, and other alteration mechanisms that altered particles during and after formation. Variation in particle morphologic parameters along traverse is consistent with crossing mapped geologic unit boundaries. Texture is divided into four types: vesicular, smooth and flat-faceted, rough and flat-faceted, and very rough. Sphericity and roundness are intermediate and low, respectively, comparable to particles moved by high-energy transport or to crushed particles. This indicates intermittent, high-energy emplacement or modification of a single lithology, rather than systematic, continuous low-energy abrasion or wear over time. Comparison with particle morphology at other Mars landing sites is consistent with the hypothesis that no secondary systematic transport or wide-scale chemical alteration was active at a significant enough level to alter macromorphology. In particular, particle morphology at the Mars Pathfinder site shows stronger evidence of abrasion than along the Spirit traverse, suggesting Mars Pathfinder particles have undergone abrasion processes that particles in this study area have not. Additionally, morphology indices have correlation coefficients near zero, indicating that a fluvial transport mechanism is likely not responsible for morphology. Morphology and texture are instead related to origin and composition rather than subsequent modification. Morphology and texture support a volcanic origin, possibly without modification, but most likely altered primarily by ballistic impact, implying that the Spirit landing site and traverse may be utilized in the future as a standard site for characterization of impact-derived morphology.

Investigation of Mechanical, Microstructural and Corrosion behaviour of Titanium subjected to Laser Peening with and without Ablation

NASA Astrophysics Data System (ADS)

Ranjith Kumar, G.; Sowmya Joshi, K.; Rajyalakshmi, G.; Kalainathan, S.; Prabhakaran, S.

2018-02-01

Present competitive world is looking for Components with high strength and fatigue resistance finding their applications in aerospace, turbine parts and especially bio-medical devices with high bio-compatibility. Advanced surface engineering techniques are required to produce parts of higher complexities and desirable surface qualities. Laser peening stood first in a row of all various surface treatments of metallic component. This paper discusses about the mechanical properties like hardness and roughness then the surface morphology and the corrosion behaviour of the laser peened titanium samples with and without coating.

Experimental studies of contact angle hysteresis phenomena on polymer surfaces – Toward the understanding and control of wettability for different applications.

PubMed

Grundke, K; Pöschel, K; Synytska, A; Frenzel, R; Drechsler, A; Nitschke, M; Cordeiro, A L; Uhlmann, P; Welzel, P B

2015-08-01

Contact angle hysteresis phenomena on polymer surfaces have been studied by contact angle measurements using sessile liquid droplets and captive air bubbles in conjunction with a drop shape method known as Axisymmetric Drop Shape Analysis - Profile (ADSA-P). In addition, commercially available sessile drop goniometer techniques were used. The polymer surfaces were characterized with respect to their surface structure (morphology, roughness, swelling) and surface chemistry (elemental surface composition, acid-base characteristics) by scanning electron microscopy (SEM), scanning force microscopy (SFM), ellipsometry, X-ray photoelectron spectroscopy (XPS) and streaming potential measurements. Heterogeneous polymer surfaces with controlled roughness and chemical composition were prepared by different routes using plasma etching and subsequent dip coating or grafting of polymer brushes, anodic oxidation of aluminium substrates coated with thin polymer films, deposition techniques to create regular patterned and rough fractal surfaces from core-shell particles, and block copolymers. To reveal the effects of swelling and reorientation at the solid/liquid interface contact angle hysteresis phenomena on polyimide surfaces, cellulose membranes, and thermo-responsive hydrogels have been studied. The effect of different solutes in the liquid (electrolytes, surfactants) and their impact on contact angle hysteresis were characterized for solid polymers without and with ionizable functional surface groups in aqueous electrolyte solutions of different ion concentrations and pH and for photoresist surfaces in cationic aqueous surfactant solutions. The work is an attempt toward the understanding of contact angle hysteresis phenomena on polymer surfaces aimed at the control of wettability for different applications. Copyright © 2014 Elsevier B.V. All rights reserved.

Sensor-based monitoring and inspection of surface morphology in ultraprecision manufacturing processes

NASA Astrophysics Data System (ADS)

Rao, Prahalad Krishna

This research proposes approaches for monitoring and inspection of surface morphology with respect to two ultraprecision/nanomanufacturing processes, namely, ultraprecision machining (UPM) and chemical mechanical planarization (CMP). The methods illustrated in this dissertation are motivated from the compelling need for in situ process monitoring in nanomanufacturing and invoke concepts from diverse scientific backgrounds, such as artificial neural networks, Bayesian learning, and algebraic graph theory. From an engineering perspective, this work has the following contributions: 1. A combined neural network and Bayesian learning approach for early detection of UPM process anomalies by integrating data from multiple heterogeneous in situ sensors (force, vibration, and acoustic emission) is developed. The approach captures process drifts in UPM of aluminum 6061 discs within 15 milliseconds of their inception and is therefore valuable for minimizing yield losses. 2. CMP process dynamics are mathematically represented using a deterministic multi-scale hierarchical nonlinear differential equation model. This process-machine inter-action (PMI) model is evocative of the various physio-mechanical aspects in CMP and closely emulates experimentally acquired vibration signal patterns, including complex nonlinear dynamics manifest in the process. By combining the PMI model predictions with features gathered from wirelessly acquired CMP vibration signal patterns, CMP process anomalies, such as pad wear, and drifts in polishing were identified in their nascent stage with high fidelity (R2 ~ 75%). 3. An algebraic graph theoretic approach for quantifying nano-surface morphology from optical micrograph images is developed. The approach enables a parsimonious representation of the topological relationships between heterogeneous nano-surface fea-tures, which are enshrined in graph theoretic entities, namely, the similarity, degree, and Laplacian matrices. Topological invariant measures (e.g., Fiedler number, Kirchoff index) extracted from these matrices are shown to be sensitive to evolving nano-surface morphology. For instance, we observed that prominent nanoscale morphological changes on CMP processed Cu wafers, although discernible visually, could not be tractably quantified using statistical metrology parameters, such as arithmetic average roughness (Sa), root mean square roughness (Sq), etc. In contrast, CMP induced nanoscale surface variations were captured on invoking graph theoretic topological invariants. Consequently, the graph theoretic approach can enable timely, non-contact, and in situ metrology of semiconductor wafers by obviating the need for reticent profile mapping techniques (e.g., AFM, SEM, etc.), and thereby prevent the propagation of yield losses over long production runs.

SEM and AFM studies of dip-coated CuO nanofilms.

PubMed

Dhanasekaran, V; Mahalingam, T; Ganesan, V

2013-01-01

Cupric oxide (CuO) semiconducting thin films were prepared at various copper sulfate concentrations by dip coating. The copper sulfate concentration was varied to yield films of thicknesses in the range of 445-685 nm by surface profilometer. X-ray diffraction patterns revealed that the deposited films were polycrystalline in nature with monoclinic structure of (-111) plane. The surface morphology and topography of monoclinic-phase CuO thin films were examined using scanning electron microscopy (SEM) and atomic force microscopy (AFM), respectively. Surface roughness profile was plotted using WSxM software and the estimated surface roughness was about ∼19.4 nm at 30 mM molar concentration. The nanosheets shaped grains were observed by SEM and AFM studies. The stoichiometric compound formation was observed at 30 mM copper sulfate concentration prepared film by EDX. The indirect band gap energy of CuO films was increased from 1.08 to 1.20 eV with the increase of copper sulfate concentrations. Copyright © 2012 Wiley Periodicals, Inc.

In situ non-destructive measurement of biofilm thickness and topology in an interferometric optical microscope

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

Larimer, Curtis; Suter, Jonathan D.; Bonheyo, George

Biofilms are ubiquitous and deleteriously impact a wide range of industrial processes, medical and dental health issues, and environmental problems such as transport of invasive species and the fuel efficiency of ocean going vessels. Biofilms are difficult to characterize when fully hydrated, especially in a non-destructive manner, because of their soft structure and water-like bulk properties. Herein we describe a non-destructive high resolution method of measuring and monitoring the thickness and topology of live biofilms of using white light interferometric optical microscopy. Using this technique, surface morphology, surface roughness, and biofilm thickness can be measured non-destructively and with high resolutionmore » as a function of time without disruption of the biofilm activity and processes. The thickness and surface topology of a P. putida biofilm were monitored growing from initial colonization to a mature biofilm. Typical bacterial growth curves were observed. Increase in surface roughness was a leading indicator of biofilm growth.« less

Real-time and post-plasma studies of influence of low levels of tungsten on carbon erosion and surface evolution behaviour in D2 plasma

NASA Astrophysics Data System (ADS)

Weilnboeck, F.; Fox-Lyon, N.; Oehrlein, G. S.; Doerner, R. P.

2010-02-01

A profound influence of monolayer tungsten coverage of hard carbon films on the evolution of carbon surface erosion behaviour, surface chemistry and morphology in D2 plasma has been established by real-time ellipsometry, x-ray photoelectron spectroscopy and atomic force microscopy measurements. The erosion of tungsten-covered carbon showed two distinct stages of plasma material interactions: rapid tungsten removal during the initial erosion period and steady-state amorphous carbon removal accompanied by large-scale surface roughness development. The initial removal of tungsten takes place at a rate that significantly exceeds typical sputter yields at the ion energies used here and is attributed to elimination of weakly bonded tungsten from the surface. The tungsten remaining on the a-C : H film surface causes surface roughness development of the eroding carbon surface by a masking effect, and simultaneously leads to a seven fold reduction of the steady-state carbon erosion rate for long plasma surface interaction times (~100 s). Results presented are of direct relevance for material transport and re-deposition, and the interaction of those films with plasma in the divertor region and on mirror surfaces of fusion devices.

Formation and characterization of perpendicular mode Si ripples by glancing angle O{sub 2}{sup +} sputtering at room temperature

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

Mollick, S. A.; Ghose, D.

Off-normal low energy ion beam sputtering of solid surfaces often leads to morphological instabilities resulting in the spontaneous formation of ripple structures in nanometer length scales. In the case of Si surfaces at ambient temperature, ripple formation is found to take place normally at lower incident angles with the wave vector parallel to the ion beam direction. The absence of ripple pattern on Si surface at larger angles is due to the dominance of ion beam polishing effect. We have shown that a gentle chemical roughening of the starting surface morphology can initiate ripple pattern under grazing incidence ion beammore » sputtering (theta>64 deg. with respect to the surface normal), where the ripple wave vector is perpendicular to the ion beam direction. The characteristics of the perpendicular mode ripples are studied as a function of pristine surface roughness (2-30 nm) and projectile fluence (5x10{sup 16}-1.5x10{sup 18} O atoms cm{sup -2}). The quality of the morphological structure is assessed from the analysis of ion induced topological defects.« less

Atomic force microscopy study on topography of films produced by ion-based techniques

NASA Astrophysics Data System (ADS)

Wang, X.; Liu, X. H.; Zou, S. C.; Martin, P. J.; Bendavid, A.

1996-09-01

The evolution of surface morphologies of films prepared by ion-based deposition techniques has been investigated by atomic force microscopy. Two deposition processes, filtered arc deposition (FAD) and ion-beam-assisted deposition, where low-energy (<100 eV) ion irradiation and high-energy (several tens of keV) ion-beam bombardment concurrent with film growth were involved, respectively, have been employed to prepare TiN and Al films. Comparative studies on the effect of energetic ions on the development of topography have been performed between the low-ion-energy regime and high-ion-energy regime. In addition, the relationship between topography and mechanical properties of thin films has been revealed, by involving thin films prepared by thermal evaporation deposition (TED), where almost all depositing particles are neutral. In the images of the TED TiN and Al films, a large number of porous and deep boundaries between columnar grains was observed, suggesting a very rough and loose surface. In contrast, the FAD films exhibited much denser surface morphologies, although still columnar. The root-mean-square roughness of the FAD films was less than 1 Å. Hardness test and optical parameter measurement indicated that the FAD films were much harder and, in the case of optical films, much more transparent than the TED films, which was considered to arise from the denser surface morphologies rather than crystallization of the films. The high density and super smoothness of the FAD films, and the resultant mechanical and optical properties superior to those of the TED films, were attributed to the enhancement of surface migration of the deposited adatoms in the FAD process, which could provide intensive low-energy ion irradiation during film growth. As for topography modification by high-energy ion-beam bombardment concurrent with film growth, in addition to the increase of surface diffusion due to elastic collision and thermal spikes, physical sputtering must be considered while explaining the development of the film topography. Both surface migration enhancement and sputtering played important roles in the case of high-energy heavy-ion-beam bombardment, under which condition surface morphology characterized by dense columns with larger dimension and deep clean boundaries was formed. However, under high-energy light-ion-beam bombardment, the sputtering was dominant, and the variation of sputtering coefficient with position on the surface of growing film led to the formation of cones.

Surface analysis of Fe-Co-Mo electrolytic coatings

NASA Astrophysics Data System (ADS)

Yar-Mukhamedova, G. Sh; Sakhnenko, N. D.; Ved', M. V.; Yermolenko, I. Yu; Zyubanova, S. I.

2017-06-01

Coatings Fe-Co-Mo with a composition of 47 at.% iron, 28 at.% Cobalt and 25 at.% Molybdenum were deposited from citrate electrolyte using pulse electrolysis mode. Scanning electron and atomic force microscopy have established the surface morphology and topography. It was identified the parts with a globular structure which have an average size of 0.2-0.5μm and singly located sharp grains. Within the same scan area sites with developed surface were detected the topography of which is identical to the crystal structure of cobalt with the crystallites size of 0.2-1.75μm. The parameters Ra and Rq for parts with different morphology as well as average characteristics of coatings demonstrated the low roughness of the surface. It is found that the coercive force of Fe-Co-Mo films is 7-10 Oe, which allow us to classify the Fe-Co-Mo coatings as soft magnetic materials.

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

NASA Astrophysics Data System (ADS)

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

2017-12-01

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

Electrodeposited Ni nanowires-track etched P.E.T. composites as selective solar absorbers

NASA Astrophysics Data System (ADS)

Lukhwa, R.; Sone, B.; Kotsedi, L.; Madjoe, R.; Maaza, M.

2018-05-01

This contribution reports on the structural, optical and morphological properties of nanostructured flexible solar-thermal selective absorber composites for low temperature applications. The candidate material in the system is consisting of electrodeposited nickel nano-cylinders embedded in track-etched polyethylene terephthalate (PET) host membrane of pore sizes ranging between 0.3-0.8µm supported by conductive nickel thin film of about 0.5µm. PET were irradiated with 11MeV/u high charged xenon (Xe) ions at normal incidence. The tubular and metallic structure of the nickel nano-cylinders within the insulator polymeric host forms a typical ceramic-metal nano-composite "Cermet". The produced material was characterized by the following techniques: X-ray diffraction (XRD) for structural characterization to determine preferred crystallographic structure, and grain size of the materials; Scanning electron microscopy (SEM) to determine surface morphology, particle size, and visual imaging of distribution of structures on the surface of the substrate; Atomic force microscopy (AFM) to characterize surface roughness, surface morphology, and film thickness, and UV-Vis-NIR spectrophotometer to measure the reflectance, then to determine solar absorption

Deposition and characterization of molybdenum thin films using dc-plasma magnetron sputtering

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

Khan, Majid, E-mail: majids@hotmail.com; Islam, Mohammad, E-mail: mohammad.islam@gmail.com

2013-12-15

Molebdenum (Mo) thin films were deposited on well-cleaned soda-lime glass substrates using DC-plasma magnetron sputtering. In the design of experiment deposition was optimized for maximum beneficial characteristics by monitoring effect of process variables such as deposition power (100–200 W). Their electrical, structural and morphological properties were analyzed to study the effect of these variables. The electrical resistivity of Mo thin films could be reduced by increasing deposition power. Within the range of analyzed deposition power, Mo thin films showed a mono crystalline nature and the crystallites were found to have an orientation along [110] direction. The surface morphology of thinmore » films showed that a highly dense micro structure has been obtained. The surface roughness of films increased with deposition power. The adhesion of Mo thin films could be improved by increasing the deposition power. Atomic force microscopy was used for the topographical study of the films and to determine the roughness of the films. X-ray diffractrometer and scanning electron microscopy analysis were used to investigate the crystallinity and surface morphology of the films. Hall effect measurement system was used to find resistivity, carrier mobility and carrier density of deposited films. The adhesion test was performed using scotch hatch tape adhesion test. Mo thin films prepared at deposition power of 200 W, substrate temperature of 23°C and Ar pressure of 0.0123 mbar exhibited a mono crystalline structure with an orientation along (110) direction, thickness of ∼550 nm and electrical resistivity value of 0.57 × 10{sup −4} Ω cm.« less

Banded Spherulitic Morphology in Blends of Poly(propylene fumarate) and Poly( -caprolactone) and Interaction with MC3T3-E1 Cells

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

Wang, Kan; Jesse, Stephen; Wang, Shanfeng

2012-01-01

The thermal properties, morphological development, crystallization behavior, and miscibility of semicrystalline PCL and its 25, 50, and 75 wt% blends with amorphous PPF in spin-coated thin films crystallized at various crystallization temperatures (T{sub c}) from 25 to 52 C are investigated. The surface roughness of PPF/PCL ({phi}{sub PCL} = 75%) films increases with increasing T{sub c} and consequently the adsorption of serum proteins is also increased. No significant variance is found in surface hydrophilicity or in mouse MC3T3-E1 cell attachment, spreading, and proliferation on PPF/PCL ({phi}{sub PCL} = 75%) films crystallized isothermally at 25, 37, and 45 C, because ofmore » low ridge height, nonuniformity in structures, and PPF surface segregation« less

Fabrication and Characterization of Polyvinylidene Fluoride Microfilms for Microfluidic Applications

NASA Astrophysics Data System (ADS)

Rao, Yammani Venkat Subba; Raghavan, Aravinda Narayanan; Viswanathan, Meenakshi

2016-10-01

The ability to create patterns of piezo responsive material on smooth substrate is an important method to develop efficient microfluidic mixers. This paper reports the fabrication of Poly vinylidene fluoride microfilms using spin-coating on smooth glass surface. The suitable crystalline phases, surface morphology and microstructural properties of the PVDF films have been investigated. We found that films of average thickness 10μm, had average roughness of 0.13μm. These PVDF films are useful in microfluidic mixer applications.

Bone marrow mesenchymal stem cell response to nano-structured oxidized and turned titanium surfaces.

PubMed

Annunziata, Marco; Oliva, Adriana; Buosciolo, Antonietta; Giordano, Michele; Guida, Agostino; Guida, Luigi

2012-06-01

The aim of this study was to analyse the topographic features of a novel nano-structured oxidized titanium implant surface and to evaluate its effect on the response of human bone marrow mesenchymal stem cells (BM-MSC) compared with a traditional turned surface. The 10 × 10 × 1 mm turned (control) and oxidized (test) titanium samples (P.H.I. s.r.l.) were examined by scanning electron microscopy (SEM) and atomic force microscopy (AFM) and characterized by height, spatial and hybrid roughness parameters at different dimensional ranges of analysis. Primary cultures of BM-MSC were seeded on titanium samples and cell morphology, adhesion, proliferation and osteogenic differentiation, in terms of alkaline phosphatase activity, osteocalcin synthesis and extracellular matrix mineralization, were evaluated. At SEM and AFM analyses turned samples were grooved, whereas oxidized surfaces showed a more complex micro- and nano-scaled texture, with higher values of roughness parameters. Cell adhesion and osteogenic parameters were greater on oxidized (P<0.05 at least) vs. turned surfaces, whereas the cell proliferation rate was similar on both samples. Although both control and test samples were in the range of average roughness proper of smooth surfaces, they exhibited significantly different topographic properties in terms of height, spatial and, mostly, of hybrid parameters. This different micro- and nano-structure resulted in an enhanced adhesion and differentiation of cells plated onto the oxidized surfaces. © 2011 John Wiley & Sons A/S.

The Role of Titanium Surface Microtopography on Adhesion, Proliferation, Transformation, and Matrix Deposition of Corneal Cells.

PubMed

Zhou, Chengxin; Lei, Fengyang; Chodosh, James; Paschalis, Eleftherios I

2016-04-01

Titanium (Ti) is an excellent implantable biomaterial that can be further enhanced by surface topography optimization. Despite numerous data from orthopedics and dentistry, the effect of Ti surface topography on ocular cells is still poorly understood. In light of the recent adaptation of Ti in the Boston Keratoprosthesis artificial cornea, we attempted to perform an extended evaluation of the effect of Ti surface topography on corneal cell adhesion, proliferation, cytotoxicity, transformation, and matrix deposition. Different surface topographies were generated on medical grade Ti-6Al-4V-ELI (extra-low interstitial), with linearly increased roughness (polished to grit blasted). Biological response was evaluated in vitro using human corneal limbal epithelial (HCLE) cells, stromal fibroblasts (HCF), and endothelial cells (HCEnC). None of the Ti surface topographies caused cytotoxicity to any of the three corneal cell types. However, rough Ti surface inhibited HCLE and HCF cell adhesion and proliferation, while HCEnC proliferation was unaffected. Long-term experiments with HCF revealed that rough Ti surface with R(a) (the arithmetic average of the profile height from the mean line) ≥ 1.15 μm suppressed HCF focal adhesion kinase phosphorylation, changed fibroblast morphology, and caused less aligned and reduced deposition of collagen matrix as compared to smooth Ti (R(a) ≤ 0.08 μm). In the presence of transforming growth factor β1 (TGFβ1) stimulation, rough Ti inhibited alpha-smooth muscle actin (α-SMA) expression and collagen deposition, leading to decreased myofibroblast transformation and disorganization of the collagen fibrils as compared to smooth Ti. This study suggests that Ti surface topography regulates corneal cell behavior in a tissue-dependent manner that varies across the corneal strata. Contrary to the accepted paradigm, smooth surface topography can enhance cell adhesion and proliferation and increase matrix deposition by corneal cells.

Gold nanoparticles deposited on glass: physicochemical characterization and cytocompatibility

PubMed Central

2013-01-01

Properties of gold films sputtered under different conditions onto borosilicate glass substrate were studied. Mean thickness of sputtered gold film was measured by gravimetry, and film contact angle was determined by goniometry. Surface morphology was examined by atomic force microscopy, and electrical sheet resistance was determined by two-point technique. The samples were seeded with rat vascular smooth muscle cells, and their adhesion and proliferation were studied. Gold depositions lead to dramatical changes in the surface morphology and roughness in comparison to pristine substrate. For sputtered gold structures, the rapid decline of the sheet resistance appears on structures deposited for the times above 100 s. The thickness of deposited gold nanoparticles/layer is an increasing function of sputtering time and current. AFM images prove the creation of separated gold islands in the initial deposition phase and a continuous gold coverage for longer deposition times. Gold deposition has a positive effect on the proliferation of vascular smooth muscle cells. Largest number of cells was observed on sample sputtered with gold for 20 s and at the discharge current of 40 mA. This sample exhibits lowest contact angle, low relative roughness, and only mild increase of electrical conductivity. PMID:23705782

Structural ordering and interface morphology in symmetrically strained(GaIn)As/Ga(PAs) superlattices grown on off-oriented GaAs(100)

NASA Astrophysics Data System (ADS)

Giannini, C.; Tapfer, L.; Zhuang, Y.; de Caro, L.; Marschner, T.; Stolz, W.

1997-02-01

In this work we investigate the structural properties of symmetrically strained (GaIn)As/GaAs/Ga(PAs)/GaAs superlattices by means of x-ray diffraction, reciprocal-space mapping, and x-ray reflectivity. The multilayers were grown by metalorganic vapor-phase epitaxy on (001) GaAs substrates intentionally off-oriented towards one of the nearest <110> directions. High-resolution triple-crystal reciprocal-space maps recorded for different azimuth angles in the vicinity of the (004) Bragg diffraction clearly show a double periodicity of the x-ray peak intensity that can be ascribed to a lateral and a vertical periodicity occurring parallel and perpendicular to the growth surface. Moreover, from the intensity modulation of the satellite peaks, a lateral-strain gradient within the epilayer unit cell is found, varying from a tensile to a compressive strain. Thus, the substrate off-orientation promotes a lateral modulation of the layer thickness (ordered interface roughness) and of the lattice strain, giving rise to laterally ordered macrosteps. In this respect, contour maps of the specular reflected beam in the vicinity of the (000) reciprocal lattice point were recorded in order to inspect the vertical and lateral interface roughness correlation. A semiquantitative analysis of our results shows that the interface morphology and roughness is greatly influenced by the off-orientation angle and the lateral strain distribution. Two mean spatial wavelengths can be determined, one corresponding exactly to the macrostep periodicity and the other indicating a further interface waviness along the macrosteps. The same spatial periodicities were found on the surface by atomic-force-microscopy images confirming the x-ray results and revealing a strong vertical correlation of the interfaces up to the outer surface.

Adsorption and association of a symmetric PEO-PPO-PEO triblock copolymer on polypropylene, polyethylene, and cellulose surfaces.

PubMed

Li, Yan; Liu, Hongyi; Song, Junlong; Rojas, Orlando J; Hinestroza, Juan P

2011-07-01

The association of a symmetric polyoxyethylene-polyoxypropylene-polyoxyethylene (PEO(19)-PPO(29)-PEO(19)) triblock copolymer adsorbed from aqueous solutions onto polypropylene (PP), polyethylene (PE), and cellulose surfaces was probed using Atomic Force Microscopy (AFM). Significant morphological differences between the polyolefin substrates (PP and PE) and the cellulose surfaces were observed after immersion of the films in the PEO(19)-PPO(29)-PEO(19) solutions. When the samples were scanned, while immersed in solutions of the triblock copolymer, it was revealed that the structures adsorbed on the polyolefin surfaces were smoothed by the adsorbed PEO(19)-PPO(29)-PEO(19). In contrast, those structures on the hydrophilic cellulose surfaces were sharpened. These observations were related to the roughness of the substrate and the energy of interaction between the surfaces and the PEO and PPO polymer segments. The interaction energy between each of the blocks and the surface was calculated using molecular dynamics simulations. It is speculated that the associative structures amply reported in aqueous solution at concentrations above the critical micelle concentration, CMC, are not necessarily preserved upon adsorption; instead, it appears that molecular arrangements of the anchor-buoy type and hemimicelles prevail. The reported data suggests that the roughness of the surface, as well as its degree of hydrophobicity, have a large influence on the nature of the resulting adsorbed layer. The reported observations are valuable in explaining the behavior of finishing additives and lubricants commonly used in textile and fiber processing, as well as the effect of the morphology of the boundary layers on friction and wear, especially in the case of symmetric triblock copolymers, which are commonly used as antifriction, antiwear additives.

Effects of Structural Properties of Electrospun TiO2 Nano-fiber Meshes on their Osteogenic Potential

PubMed Central

Wang, Xiaokun; Gittens, Rolando A.; Song, Rosemary; Tannenbaum, Rina; Olivares-Navarrete, Rene; Schwartz, Zvi; Chen, Haifeng; Boyan, Barbara D.

2011-01-01

Ideal outcomes in the field of tissue engineering and regenerative medicine involve biomaterials that can enhance cell differentiation and production of local factors for natural tissue regeneration without the use of systemic drugs. Biomaterials typically used in tissue engineering applications include polymeric scaffolds that mimic the 3-D structural environment of the native tissue, but these are often functionalized with proteins or small peptides to improve their biological performance. For bone applications, titanium (Ti) implants, or more appropriately the titania (TiO2) passive oxide layer formed on their surface, have been shown to enhance osteoblast differentiation in vitro and to promote osseointegration in vivo. In this study we evaluated the effect on osteoblast differentiation of pure TiO2 nano-fiber meshes with different surface micro-roughness and nano-fiber diameters, prepared by the electrospinning method. MG63 cells were seeded on TiO2 meshes, and cell number, differentiation markers and local factor production were analyzed. The results showed that cells grew throughout the entire surfaces and with similar morphology in all groups. Cell number was sensitive to surface micro-roughness, whereas cell differentiation and local factor production was regulated by both surface roughness and nano-fiber diameter. These results indicate that scaffold structural cues alone can be used to drive cell differentiation and create an osteogenic environment without the use of exogenous factors. PMID:22075122

Plasma nanotexturing of silicon surfaces for photovoltaics applications: influence of initial surface finish on the evolution of topographical and optical properties

PubMed Central

FISCHER, GUILLAUME; DRAHI, ETIENNE; FOLDYNA, MARTIN; GERMER, THOMAS A.; JOHNSON, ERIK V.

2018-01-01

Using a plasma to generate a surface texture with feature sizes on the order of tens to hundreds of nanometers (“nanotexturing”) is a promising technique being considered to improve efficiency in thin, high-efficiency crystalline silicon solar cells. This study investigates the evolution of the optical properties of silicon samples with various initial surface finishes (from mirror polish to various states of micron-scale roughness) during a plasma nanotexturing process. It is shown that during said process, the appearance and growth of nanocone-like structures are essentially independent of the initial surface finish, as quantified by the auto-correlation function of the surface morphology. During the first stage of the process (2 min to 15 min etching), the reflectance and light-trapping abilities of the nanotextured surfaces are strongly influenced by the initial surface roughness; however, the differences tend to diminish as the nanostructures become larger. For the longest etching times (15 min or more), the effective reflectance is less than 5 % and a strong anisotropic scattering behavior is also observed for all samples, leading to very elevated levels of light-trapping. PMID:29220984

Towards an in vitro model mimicking the foreign body response: tailoring the surface properties of biomaterials to modulate extracellular matrix.

PubMed

Damanik, Febriyani F R; Rothuizen, Tonia C; van Blitterswijk, Clemens; Rotmans, Joris I; Moroni, Lorenzo

2014-09-19

Despite various studies to minimize host reaction following a biomaterial implantation, an appealing strategy in regenerative medicine is to actively use such an immune response to trigger and control tissue regeneration. We have developed an in vitro model to modulate the host response by tuning biomaterials' surface properties through surface modifications techniques as a new strategy for tissue regeneration applications. Results showed tunable surface topography, roughness, wettability, and chemistry by varying treatment type and exposure, allowing for the first time to correlate the effect of these surface properties on cell attachment, morphology, strength and proliferation, as well as proinflammatory (IL-1β, IL-6) and antiinflammatory cytokines (TGF-β1, IL-10) secreted in medium, and protein expression of collagen and elastin. Surface microstructuring, derived from chloroform partial etching, increased surface roughness and oxygen content. This resulted in enhanced cell adhesion, strength and proliferation as well as a balance of soluble factors for optimum collagen and elastin synthesis for tissue regeneration. By linking surface parameters to cell activity, we could determine the fate of the regenerated tissue to create successful soft tissue-engineered replacement.

Towards an in vitro model mimicking the foreign body response: tailoring the surface properties of biomaterials to modulate extracellular matrix

NASA Astrophysics Data System (ADS)

Damanik, Febriyani F. R.; Rothuizen, Tonia C.; van Blitterswijk, Clemens; Rotmans, Joris I.; Moroni, Lorenzo

2014-09-01

Despite various studies to minimize host reaction following a biomaterial implantation, an appealing strategy in regenerative medicine is to actively use such an immune response to trigger and control tissue regeneration. We have developed an in vitro model to modulate the host response by tuning biomaterials' surface properties through surface modifications techniques as a new strategy for tissue regeneration applications. Results showed tunable surface topography, roughness, wettability, and chemistry by varying treatment type and exposure, allowing for the first time to correlate the effect of these surface properties on cell attachment, morphology, strength and proliferation, as well as proinflammatory (IL-1β, IL-6) and antiflammatory cytokines (TGF-β1, IL-10) secreted in medium, and protein expression of collagen and elastin. Surface microstructuring, derived from chloroform partial etching, increased surface roughness and oxygen content. This resulted in enhanced cell adhesion, strength and proliferation as well as a balance of soluble factors for optimum collagen and elastin synthesis for tissue regeneration. By linking surface parameters to cell activity, we could determine the fate of the regenerated tissue to create successful soft tissue-engineered replacement.

Smooth e-beam-deposited tin-doped indium oxide for III-nitride vertical-cavity surface-emitting laser intracavity contacts

NASA Astrophysics Data System (ADS)

Leonard, J. T.; Cohen, D. A.; Yonkee, B. P.; Farrell, R. M.; DenBaars, S. P.; Speck, J. S.; Nakamura, S.

2015-10-01

We carried out a series of simulations analyzing the dependence of mirror reflectance, threshold current density, and differential efficiency on the scattering loss caused by the roughness of tin-doped indium oxide (ITO) intracavity contacts for 405 nm flip-chip III-nitride vertical-cavity surface-emitting lasers (VCSELs). From these results, we determined that the ITO root-mean-square (RMS) roughness should be <1 nm to minimize scattering losses in VCSELs. Motivated by this requirement, we investigated the surface morphology and optoelectronic properties of electron-beam (e-beam) evaporated ITO films, as a function of substrate temperature and oxygen flow and pressure. The transparency and conductivity were seen to increase with increasing temperature. Decreasing the oxygen flow and pressure resulted in an increase in the transparency and resistivity. Neither the temperature, nor oxygen flow and pressure series on single-layer ITO films resulted in highly transparent and conductive films with <1 nm RMS roughness. To achieve <1 nm RMS roughness with good optoelectronic properties, a multi-layer ITO film was developed, utilizing a two-step temperature scheme. The optimized multi-layer ITO films had an RMS roughness of <1 nm, along with a high transparency (˜90% at 405 nm) and low resistivity (˜2 × 10-4 Ω-cm). This multi-layer ITO e-beam deposition technique is expected to prevent p-GaN plasma damage, typically observed in sputtered ITO films on p-GaN, while simultaneously reducing the threshold current density and increasing the differential efficiency of III-nitride VCSELs.

Effects of O 2 and N 2/H 2 plasma treatments on the neuronal cell growth on single-walled carbon nanotube paper scaffolds

NASA Astrophysics Data System (ADS)

Yoon, Ok Ja; Lee, Hyun Jung; Jang, Yeong Mi; Kim, Hyun Woo; Lee, Won Bok; Kim, Sung Su; Lee, Nae-Eung

2011-08-01

The O 2 and N 2/H 2 plasma treatments of single-walled carbon nanotube (SWCNT) papers as scaffolds for enhanced neuronal cell growth were conducted to functionalize their surfaces with different functional groups and to roughen their surfaces. To evaluate the effects of the surface roughness and functionalization modifications of the SWCNT papers, we investigated the neuronal morphology, mitochondrial membrane potential, and acetylcholine/acetylcholinesterase levels of human neuroblastoma during SH-SY5Y cell growth on the treated SWCNT papers. Our results demonstrated that the plasma-chemical functionalization caused changes in the surface charge states with functional groups with negative and positive charges and then the increased surface roughness enhanced neuronal cell adhesion, mitochondrial membrane potential, and the level of neurotransmitter in vitro. The cell adhesion and mitochondrial membrane potential on the negatively charged SWCNT papers were improved more than on the positively charged SWCNT papers. Also, measurements of the neurotransmitter level showed an enhanced acetylcholine level on the negatively charged SWCNT papers compared to the positively charged SWCNT papers.

Experimental research on micro-pit defects of SUS 430 stainless steel strip in cold rolling process

NASA Astrophysics Data System (ADS)

Li, Changsheng; Li, Miao; Zhu, Tao; Huo, Gang

2013-05-01

In order to improve surface glossiness of stainless steel strip in tandem cold rolling, experimental research on micro-pit defects of SUS 430 ferrite stainless steel was investigated in laboratory. The surface morphology of micro-pit defects was observed by SEM. The effects of micro-pit defects on rolling reduction, roll surface roughness and emulsion parameters were analyzed. With the pass number increasing, the quantity and surface of micro-pit defects were reduced, uneven peak was decreased and gently along rolling direction, micro-pit defects had equally distributed tendency along tranverse direction. The micro-pit defects were increased with the roll surface roughness increase. The defects ratio was declined with larger gradient at pass number 1 to 3, but gentle slope at pass number 4 to 5. The effects of temperature 55° and 63°, concentration 3% and 6% of emulsion on micro-pit effects had not obvious difference. Maintain of micro-pit was effected by rolling oil or air in the micro-pit, the quality of oil was much more than the air in the micro-pit in lubrication rolling.

The Anatomy of the Blue Dragon: Changes in Lava Flow Morphology and Physical Properties Observed in an Open Channel Lava Flow as a Planetary Analogue

NASA Astrophysics Data System (ADS)

Sehlke, A.; Kobs-Nawotniak, S. E.; Hughes, S. S.; Sears, D. W. G.; Downs, M.; Whittington, A. G.; Lim, D. S. S.; Heldmann, J. L.

2017-12-01

Lava terrains on other planets and moons exhibit morphologies similar to those found on Earth, such as smooth pāhoehoe transitioning to rough `a`ā terrains based on the viscosity - strain rate relationship of the lava. Therefore, the morphology of lava flows is governed by eruptive conditions such as effusion rate, underlying slope, and the fundamental thermo-physical properties of the lava, including temperature (T), composition (X), viscosity (η), fraction of crystals (φc) and vesicles (φb), as well as bulk density (ρ). These textural and rheological changes were previously studied for Hawaiian lava, where the lava flow started as channelized pāhoehoe and transitioned into `a`ā, demonstrating a systematic trend in T, X, η, φc, φb, and ρ. NASA's FINESSE focuses on Science and Exploration through analogue research. One of the field sites is Craters of the Moon, Idaho. We present field work done at a 3.0 km long lava flow belonging to the Blue Dragon lavas erupted from a chain of spatter cones, which then coalesced into channelized flows. We acquired UAV imagery along the entire length of the flow, and generated a high resolution DTM of 5 cm/pixel, from which we derived height profiles and surface roughness values. Field work included mapping the change in surface morphology and sample collection every 150 meters. In the laboratory, we measured φc, φb, and ρ for all collected samples. Viscosity measurements were carried out by concentric cylinder viscometry at subliquidus temperatures between 1310ºC to 1160ºC to study the rheology of the lava, enabling us to relate changes in flow behavior to T and φc. Our results are consistent with observations made for Hawaiian lava, including increasing bulk density downflow, and porosity changing from connected to isolated pore space. Crystallinity increases downflow, and the transition from pāhoehoe to `a`ā occurs between 1230ºC to 1150ºC, which is prompted by nucleation and growth of plagioclase microcrystals, strongly increasing the viscosity of the lava several orders of magnitude. The results of this study allows us to correlate T, X, η, φc, φb, and ρ to the lava flow morphology expressed as surface roughness, which can then be used as a tool to infer these physical properties of the rocks for open channel lava flows on other airless bodies, such as the Moon and Mercury, based on DTMs.

Electrochemical corrosion behavior and MG-63 osteoblast-like cell response of surface-treated titanium

NASA Astrophysics Data System (ADS)

Kim, Hak-Kwan; Jang, Ju-Woong

2004-10-01

Commercially pure titanium is used as a clinical implant material for many orthopedic and dental implant devices owing to its excellent corrosion resistance and good biocompatibility. However, there remains concern over the release of metal ions from prostheses and unresolved questions about its behavior in a biological environment. Our research investigated the influence of surface oxide thickness and phase on the corrosion resistance in 0.9% NaCl solution by potentiostat and XRD. Also, the MG-63 osteoblast like cell morphology and proliferation were studied to evaluate the biocompatibility in terms of surface treatment. It is demonstrated that a substantial decrease in the current density may be attained due to surface oxide thickening and phase transformation by thermal oxidation. The osteoblast adhesion morphology and proliferation data indicated that the osteoblast cell response is not conspicuously influenced by the thermal oxidation and nitric acid passivation treatments but by surface roughness and porosity of 3rd networking.

Surface structuring in polypropylene using Ar+ beam sputtering: Pattern transition from ripples to dot nanostructures

NASA Astrophysics Data System (ADS)

Goyal, Meetika; Aggarwal, Sanjeev; Sharma, Annu; Ojha, Sunil

2018-05-01

Temporal variations in nano-scale surface morphology generated on Polypropylene (PP) substrates utilizing 40 keV oblique argon ion beam have been presented. Due to controlled variation of crucial beam parameters i.e. ion incidence angle and erosion time, formation of ripple patterns and further its transition into dot nanostructures have been realized. Experimental investigations have been supported by evaluation of Bradley and Harper (B-H) coefficients estimated using SRIM (The Stopping and Range of Ions in Matter) simulations. Roughness of pristine target surfaces has been accredited to be a crucial factor behind the early time evolution of nano-scale patterns over the polymeric surface. Study of Power spectral density (PSD) spectra reveals that smoothing mechanism switch from ballistic drift to ion enhanced surface diffusion (ESD) which can be the most probable cause for such morphological transition under given experimental conditions. Compositional analysis and depth profiling of argon ion irradiated specimens using Rutherford Backscattering Spectroscopy (RBS) has also been correlated with the AFM findings.

FAS grafted superhydrophobic ceramic membrane

NASA Astrophysics Data System (ADS)

Lu, Jun; Yu, Yun; Zhou, Jianer; Song, Lixin; Hu, Xingfang; Larbot, Andre

2009-08-01

The hydrophobic properties of γ-Al 2O 3 membrane have been obtained by grafting fluoroalkylsilane (FAS) on the surface of the membrane. The following grafting parameters were studied: the eroding time of the original membrane, the grafting time, the concentration of FAS solution and the multiplicity of grafting. Hydrophobicity of the membranes was characterized by contact angle (CA) measurement. The thermogravimetric analysis (TGA) was used to investigate the weight loss process (25-800 °C) of the fluoroalkylsilane grafted on Al 2O 3 powders under different grafting conditions. The morphologies of the membranes modified under different parameters were examined by field emission scanning electron microscopy (FE-SEM) and the surface roughness (Ra) was measured using white light interferometers. A needle-like structure was observed on the membrane surface after modification, which causes the change of Ra. On the results above, we speculated a model to describe the reaction between FAS and γ-Al 2O 3 membrane surface as well as the formed surface morphology.

Accelerated Degradation Behavior and Cytocompatibility of Pure Iron Treated with Sandblasting.

PubMed

Zhou, Juncen; Yang, Yuyun; Alonso Frank, Micael; Detsch, Rainer; Boccaccini, Aldo R; Virtanen, Sannakaisa

2016-10-12

Fe-based materials are of interest for use in biodegradable implants. However, their corrosion rate in the biological environment may be too slow for the targeted applications. In this work, sandblasting is applied as a successful surface treatment for increasing the degradation rate of pure iron in simulated body fluid. Two sandblasting surfaces with different roughness present various surface morphologies but similar degradation products. Electrochemistry tests revealed that sandblasted samples have a higher corrosion rate compared to that of bare iron, and even more noteworthy, the degradation rate of sandblasted samples remains significantly higher during long-term immersion tests. On the basis of our experimental results, the most plausible reasons behind the fast degradation rate are the special properties of sandblasted surfaces, including the change of surface composition (for the early stage), high roughness (occluded surface sites), and high density of dislocations. Furthermore, the cytocompatibility was studied on sandblasting surfaces using human osteoblast-like cells (MG-63) by indirect and direct contact methods. Results revealed that sandblasting treatment brings no adverse effect to the growth of MG-63 cells. This work demonstrates the significant potential of sandblasting for controlling the degradation behavior of iron-based materials for biomedical applications.

A scanning electron microscope study of olivine crystal surfaces

NASA Technical Reports Server (NTRS)

Olsen, E. J.; Grossman, L.

1974-01-01

SEM photographs were taken of euhedral olivine grains from the Murchison C2 chondrite and several terrestrial and lunar occurrences. In general, the crystal faces of the meteorite grains are rough and uneven, with irregular growth patterns. They are very similar to crystal faces on terrestrial olivine grains that formed by sublimation from a vapor phase. They are very different from the relatively smooth and featureless surfaces of magmatic olivine crystals that precipitated from igneous melts. Qualitatively, the surface morphology of the crystal supports the contention that many euhedral crystals of olivine in C2 meteorites condensed from a gas phase.

Prenatally administered HMB modifies the enamel surface roughness in spiny mice offspring: An atomic force microscopy study.

PubMed

Świetlicka, Izabela; Muszyński, Siemowit; Tomaszewska, Ewa; Dobrowolski, Piotr; Kwaśniewska, Anita; Świetlicki, Michał; Skic, Anna; Gołacki, Krzysztof

2016-10-01

The aim of this research was to check the effect of the prenatally administered β-hydroxy β-methylbutyrate (HMB) on the development of enamel surface of the spiny mice offspring. The spiny mice dams were randomly assigned into three groups: control group (not supplemented with HMB) and two experimental groups in which powdered HMB was given at the daily dosage of 0.2g/kg of body weight (group I) and 0.02g/kg of body weight (group II) during the last period of gestation. Newborn pups were euthanized by CO 2 inhalation. The morphology of incisor teeth was analysed using atomic force microscopy (AFM) in semi-contact mode in the height, magnitude and phase domains. Height images became a basis for determination of surface roughness parameters. Conducted study indicated that maternal HMB administration markedly influences enamel development. Enamel of offspring's teeth in both experimental groups was characterized by significantly smaller values of indices describing surface roughness and profile. HMB supplementation influenced the calculated parameters regardless of the diet type and offspring sex, however higher dose of HMB caused stronger changes in enamel surface's physical properties and could be observed in higher intensity in the male group. HMB administration caused reduction in the irregularities of enamel surface, thereby possibly reducing the probability of bacteria adhesion and caries development. These observations may serve to improve nutrition and supplementation of animals and could be a lead for further research. Copyright © 2016 Elsevier Ltd. All rights reserved.

In vivo measurement of skin surface strain and sub-surface layer deformation induced by natural tissue stretching.

PubMed

Maiti, Raman; Gerhardt, Lutz-Christian; Lee, Zing S; Byers, Robert A; Woods, Daniel; Sanz-Herrera, José A; Franklin, Steve E; Lewis, Roger; Matcher, Stephen J; Carré, Matthew J

2016-09-01

Stratum corneum and epidermal layers change in terms of thickness and roughness with gender, age and anatomical site. Knowledge of the mechanical and tribological properties of skin associated with these structural changes are needed to aid in the design of exoskeletons, prostheses, orthotics, body mounted sensors used for kinematics measurements and in optimum use of wearable on-body devices. In this case study, optical coherence tomography (OCT) and digital image correlation (DIC) were combined to determine skin surface strain and sub-surface deformation behaviour of the volar forearm due to natural tissue stretching. The thickness of the epidermis together with geometry changes of the dermal-epidermal junction boundary were calculated during change in the arm angle, from flexion (90°) to full extension (180°). This posture change caused an increase in skin surface Lagrange strain, typically by 25% which induced considerable morphological changes in the upper skin layers evidenced by reduction of epidermal layer thickness (20%), flattening of the dermal-epidermal junction undulation (45-50% reduction of flatness being expressed as Ra and Rz roughness profile height change) and reduction of skin surface roughness Ra and Rz (40-50%). The newly developed method, DIC combined with OCT imaging, is a powerful, fast and non-invasive methodology to study structural skin changes in real time and the tissue response provoked by mechanical loading or stretching. Copyright © 2016 The Authors. Published by Elsevier Ltd.. All rights reserved.

Effect of nanoscale surface roughness on the bonding energy of direct-bonded silicon wafers

NASA Astrophysics Data System (ADS)

Miki, N.; Spearing, S. M.

2003-11-01

Direct wafer bonding of silicon wafers is a promising technology for manufacturing three-dimensional complex microelectromechanical systems as well as silicon-on-insulator substrates. Previous work has reported that the bond quality declines with increasing surface roughness, however, this relationship has not been quantified. This article explicitly correlates the bond quality, which is quantified by the apparent bonding energy, and the surface morphology via the bearing ratio, which describes the area of surface lying above a given depth. The apparent bonding energy is considered to be proportional to the real area of contact. The effective area of contact is defined as the area sufficiently close to contribute to the attractive force between the two bonding wafers. Experiments were conducted with silicon wafers whose surfaces were roughened by a buffered oxide etch solution (BOE, HF:NH4F=1:7) and/or a potassium hydroxide solution. The surface roughness was measured by atomic force microscopy. The wafers were direct bonded to polished "monitor" wafers following a standard RCA cleaning and the resulting bonding energy was measured by the crack-opening method. The experimental results revealed a clear correlation between the bonding energy and the bearing ratio. A bearing depth of ˜1.4 nm was found to be appropriate for the characterization of direct-bonded silicon at room temperature, which is consistent with the thickness of the water layer at the interface responsible for the hydrogen bonds that link the mating wafers.

Influence of physico-chemical, mechanical and morphological fingerpad properties on the frictional distinction of sticky/slippery surfaces

PubMed Central

Cornuault, Pierre-Henri; Carpentier, Luc; Bueno, Marie-Ange; Cote, Jean-Marc; Monteil, Guy

2015-01-01

This study investigates how the fingerpad hydrolipid film, shape, roughness and rigidity influence the friction when it rubs surfaces situated in the slippery psychophysical dimension. The studied counterparts comprised two ‘real’ (physical) surfaces and two ‘virtual’ surfaces. The latter were simulated with a tactile stimulator named STIMTAC. Thirteen women and 13 men rubbed their right forefingers against the different surfaces as their arms were displaced by a DC motor providing constant velocity and sliding distance. Tangential and normal forces were measured with a specific tribometer. The fingerpad hydrolipid film was characterized by Fourier transform infrared spectroscopy. The shape and roughness of fingers were extrapolated from replicas. Indentation measurements were carried out to determine fingerpad effective elastic modulus. A clear difference was observed between women and men in terms of friction behaviour. The concept of tactile frictional contrast (TFC) which was introduced quantifies an individual's propensity to distinguish two surfaces frictionally. The lipids/water ratio and water amount on the finger skin significantly influenced the TFC. A correlation was observed between the TFC and fingerpad roughness, i.e. the height of the fingerpad ridges. This is essentially owing to gender differences. A significant difference between men's and women's finger topography was also noted, because our results suggested that men have rougher fingers than women. The friction measurements did not correlate with the fingerpad curvature nor with the epidermal ridges' spatial period. PMID:26269232

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.

Bare and protected sputtered-noble-metal films for surface-enhanced Raman spectroscopy

NASA Astrophysics Data System (ADS)

Talaga, David; Bonhommeau, Sébastien

2014-11-01

Sputtered silver and gold films with different surface morphologies have been prepared and coated with a benzenethiol self-assembled monolayer. Rough noble metal films showed strong Raman features assigned to adsorbed benzenethiol molecules upon irradiation over a wide energy range in the visible spectrum, which disclosed the occurrence of a significant surface-enhanced Raman scattering with maximal enhancement factors as high as 6 × 106. In addition, the adsorption of ethanethiol onto silver surfaces hinders their corrosion over days while preserving mostly intact enhancement properties of naked silver. This study may be applied to develop stable and efficient metalized probes for tip-enhanced Raman spectroscopy.

Correlation of CVD Diamond Electron Emission with Film Properties

NASA Astrophysics Data System (ADS)

Bozeman, S. P.; Baumann, P. K.; Ward, B. L.; Nemanich, R. J.; Dreifus, D. L.

1996-03-01

Electron field emission from metals is affected by surface morphology and the properties of any dielectric coating. Recent results have demonstrated low field electron emission from p-type diamond, and photoemission measurements have identified surface treatments that result in a negative electron affinity (NEA). In this study, the field emission from diamond is correlated with surface treatment, surface roughness, and film properties (doping and defects). Electron emission measurements are reported on diamond films synthesized by plasma CVD. Ultraviolet photoemission spectroscopy indicates that the CVD films exhibit a NEA after exposure to hydrogen plasma. Field emission current-voltage measurements indicate "threshold voltages" ranging from approximately 20 to 100 V/micron.

Experimental investigation of nucleate pool boiling characteristics of high concentrated alumina/water nanofluids

NASA Astrophysics Data System (ADS)

Kshirsagar, Jagdeep M.; Shrivastava, Ramakant

2018-06-01

In Present study, the critical heat flux (CHF) and boiling heat transfer coefficient of alumina nanoparticles with the base fluid as deionised water is measured. The selected concentrations of nanofluids for the experimentation are from 0.3, 0.6, 0.9, 1.2 and 1.5 wt%. The main objective to select higher concentration is that to study the surface morphology of heater surface at higher concentrations and its effect on critical heat flux and heat transfer coefficient. It is observed that the critical heat flux enhancement rate decreases as concentration increases and surface roughness of heater surface decreases after 1.2 wt% concentration of nanofluids.

Ultradeep electron cyclotron resonance plasma etching of GaN

DOE PAGES

Harrison, Sara E.; Voss, Lars F.; Torres, Andrea M.; ...

2017-07-25

Here, ultradeep (≥5 μm) electron cyclotron resonance plasma etching of GaN micropillars was investigated. Parametric studies on the influence of the applied radio-frequency power, chlorine content in a Cl 2/Ar etch plasma, and operating pressure on the etch depth, GaN-to-SiO 2 selectivity, and surface morphology were performed. Etch depths of >10 μm were achieved over a wide range of parameters. Etch rates and sidewall roughness were found to be most sensitive to variations in RF power and % Cl 2 in the etch plasma. Selectivities of >20:1 GaN:SiO 2 were achieved under several chemically driven etch conditions where a maximummore » selectivity of ~39:1 was obtained using a 100% Cl 2 plasma. The etch profile and (0001) surface morphology were significantly influenced by operating pressure and the chlorine content in the plasma. Optimized etch conditions yielded >10 μm tall micropillars with nanometer-scale sidewall roughness, high GaN:SiO 2 selectivity, and nearly vertical etch profiles. These results provide a promising route for the fabrication of ultradeep GaN microstructures for use in electronic and optoelectronic device applications. In addition, dry etch induced preferential crystallographic etching in GaN microstructures is also demonstrated, which may be of great interest for applications requiring access to non- or semipolar GaN surfaces.« less

Initial oral biofilm formation on titanium implants with different surface treatments: An in vivo study.

PubMed

Ferreira Ribeiro, Cyntia; Cogo-Müller, Karina; Franco, Gilson Cesar; Silva-Concílio, Laís Regiane; Sampaio Campos, Márcia; de Mello Rode, Sigmar; Claro Neves, Ana Christina

2016-09-01

The aim of this study was to examine in vivo the initial bacterial adhesion on titanium implants with different surface treatments. Ten subjects wore oral splints containing machined pure titanium disks (Ti-M), acid-etched titanium (Ti-AE) and anodized and laser irradiated disks (Ti-AL) for 24h. After this period, disks were removed from the splints and adherent bacteria were quantified by an enzymatic assay to assess total viable bacteria and by Real Time PCR to evaluate total bacteria and Streptococcus oralis levels. Additionally, the initial adherent microorganisms were visualized by scanning electron microscopy (SEM). Titanium surface morphology was verified using SEM, and roughness was evaluated by profilometer analysis. Regarding titanium surface roughness, Ti-AL (1.423±0.397) showed significantly higher Ra values than did Ti-M (0.771±0.182) and Ti-AE (0.735±0.196) (p<0.05, ANOVA - Tahame). Ti-AE and Ti-AL presented roughened micro-structure surfaces characterized by open pores, whereas Ti-M showed long grooves alternating with planed areas. Comparing the Ti-M, Ti-AE and Ti-AL groups for viable bacteria (MTT assay), total bacteria and S. oralis quantification (qPCR), no significant differences were observed among these three groups (p>0.05, ANOVA - Tahame). SEM images showed similar bacterial adhesion on the three titanium surfaces, predominantly characterized by cocci and several bacilli, indicating an initial colonization of the oral biofilm. In conclusion, roughness and microtopography did not stimulate initial biofilm formation on titanium surfaces with different surface treatments. Copyright © 2016 Elsevier Ltd. All rights reserved.

Effect of substrate nitridation temperature on the persistent photoconductivity of unintentionally-doped GaN layer grown by PAMBE

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

Prakash, Nisha, E-mail: prakasnisha@gmail.com; Barvat, Arun; Anand, Kritika

2016-05-23

The surface roughness and defect density of GaN epitaxial layers grown on c-plane sapphire substrate are investigated and found to be dependent on nitridation temperature. GaN epitaxial layers grown after nitridation of sapphire at 200°C have a higher defect density and higher surface roughness compared to the GaN layers grown at 646°C nitridation as confirmed by atomic force microscopy (AFM). The persistent photoconductivity (PPC) was observed in both samples and it was found to be decreasing with decreasing temperature in the range 150-300°C due to long carrier lifetime and high electron mobility at low temperature. The photoresponse of the GaNmore » films grown in this study exhibit improved PPC due to their better surface morphology at 646°C nitrided sample. The point defects or extended microstructure defects limits the photocarrier lifetime and electron mobility at 200°C nitrided sample.« less

X-Ray-Based Imaging for Characterizing Heterogeneous Gas Diffusion Layers for Polymer Electrolyte Membrane Fuel Cells

NASA Astrophysics Data System (ADS)

George, Michael G.

Characterization of gas diffusion layers (GDLs) for polymer electrolyte membrane (PEM) fuel cells informs modeling studies and the manufacturers of next generation fuel cell materials. Identifying the physical properties related to the primary functions of the modern GDL (thermal, electrical, and mass transport) is necessary for understanding the impact of GDL design choices. X-ray micro-computed tomographic reconstructions of GDLs were studied to isolate GDL surface morphologies. Surface roughness was measured for a wide variety of samples and a sensitivity study highlighted the scale-dependence of surface roughness measurements. Furthermore, a spatially resolved distribution map of polytetrafluoroethylene (PTFE) in the microporous layer (MPL), critical for water management and mass transport, was identified and the existence of PTFE agglomerations was highlighted. Finally, the impact of accelerated degradation on GDL wettability and water transport increases in liquid water accumulation and oxygen mass transport resistance were quantified as a result of accelerated GDL degradation.

Effects of titanium surface topography on morphology and in vitro activity of human gingival fibroblasts.

PubMed

Ramaglia, L; Capece, G; Di Spigna, G; Bruno, M P; Buonocore, N; Postiglione, L

2013-01-01

The aim of the present study was to evaluate in vitro the biological behavior of human gingival fibroblasts cultured on two different titanium surfaces. Titanium test disks were prepared with a machined, relatively smooth (S) surface or a rough surface (O) obtained by a double acid etching procedure. Primary cultures of human gingival fibroblasts were plated on the experimental titanium disks and cultured up to 14 days. Titanium disk surfaces were analysed by scanning electron microscopy (SEM). Cell proliferation and a quantitative analysis by ELISA in situ of ECM components as CoI, FN and TN were performed. Results have shown different effects of titanium surface microtopography on cell expression and differentiation. At 96 hours of culture on experimental surfaces human gingival fibroblasts displayed a favourable cell attachment and proliferation on both surfaces although showing some differences. Both the relatively smooth and the etched surfaces interacted actively with in vitro cultures of human gingival fibroblasts, promoting cell proliferation and differentiation. Results suggested that the microtopography of a double acid-etched rough surface may induce a greater Co I and FN production, thus conditioning in vivo the biological behaviour of human gingival fibroblasts during the process of peri-implant soft tissue healing.

Impact of Gastric Acid Induced Surface Changes on Mechanical Behavior and Optical Characteristics of Dental Ceramics.

PubMed

Kulkarni, Aditi; Rothrock, James; Thompson, Jeffery

2018-01-14

To test the impact of exposure to artificial gastric acid combined with toothbrush abrasion on the properties of dental ceramics. Earlier research has indicated that immersion in artificial gastric acid has caused increased surface roughness of dental ceramics; however, the combined effects of acid immersion and toothbrush abrasion and the impact of increased surface roughness on mechanical strength and optical properties have not been studied. Three commercially available ceramics were chosen for this study: feldspathic porcelain, lithium disilicate glass-ceramic, and monolithic zirconium oxide. The specimens (10 × 1 mm discs) were cut, thermally treated as required, and polished. Each material was divided into four groups (n = 8 per group): control (no exposure), acid only, brush only, acid + brush. The specimens were immersed in artificial gastric acid (50 ml of 0.2% [w/v] sodium chloride in 0.7% [v/v] hydrochloric acid mixed with 0.16 g of pepsin powder, pH = 2) for 2 minutes and rinsed with deionized water for 2 minutes. The procedure was repeated 6 times/day × 9 days, and specimens were stored in deionized water at 37°C. Toothbrush abrasion was performed using an ISO/ADA design brushing machine for 100 cycles/day × 9 days. The acid + brush group received both treatments. Specimens were examined under SEM and an optical microscope for morphological changes. Color and translucency were measured using spectrophotometer CIELAB coordinates (L*, a*, b*). Surface gloss was measured using a gloss meter. Surface roughness was measured using a stylus profilometer. Biaxial flexural strength was measured using a mechanical testing machine. The data were analyzed by one-way ANOVA followed by Tukey's HSD post hoc test (p < 0.05). Statistically significant changes were found for color, gloss, and surface roughness for porcelain and e.max specimens. No statistically significant changes were found for any properties of zirconia specimens. The acid treatment affected the surface roughness, color, and gloss of porcelain and e.max ceramics. The changes in translucency and mechanical strength for all materials were not statistically significant. Zirconia ceramic showed resistance to all treatments. © 2018 by the American College of Prosthodontists.

The effects of implant topography on osseointegration under estrogen deficiency induced osteoporotic conditions: Histomorphometric, transcriptional and ultrastructural analysis.

PubMed

Du, Zhibin; Xiao, Yin; Hashimi, Saeed; Hamlet, Stephen M; Ivanovski, Saso

2016-09-15

Compromised bone quality and/or healing in osteoporosis are recognised risk factors for impaired dental implant osseointegration. This study examined the effects of (1) experimentally induced osteoporosis on titanium implant osseointegration and (2) the effect of modified implant surface topography on osseointegration under osteoporosis-like conditions. Machined and micro-roughened surface implants were placed into the maxillary first molar root socket of 64 ovariectomised and sham-operated Sprague-Dawley rats. Subsequent histological and SEM observations showed tissue maturation on the micro-rough surfaced implants in ovariectomised animals as early as 3days post-implantation. The degree of osseointegration was also significantly higher around the micro-rough implants in ovariectomised animals after 14days of healing although by day 28, similar levels of osseointegration were found for all test groups. The micro-rough implants significantly increased the early (day 3) gene expression of alkaline phosphatase, osteocalcin, receptor activator of nuclear factor kappa-B ligand and dentin matrix protein 1 in implant adherent cells. By day 7, the expression of inflammatory genes decreased while the expression of the osteogenic markers increased further although there were few statistically significant differences between the micro-rough and machined surfaces. Osteocyte morphology was also affected by estrogen deficiency with the size of the cells being reduced in trabecular bone. In conclusion, estrogen deficiency induced osteoporotic conditions negatively influenced the early osseointegration of machined implants while micro-rough implants compensated for these deleterious effects by enhancing osteogenic cell differentiation on the implant surface. Lower bone density, poor bone quality and osseous microstructural changes are all features characteristic of osteoporosis that may impair the osseointegration of dental implants. Using a clinically relevant trabecular bone model in the rat maxilla, we demonstrated histologically that the negative effects of surgically-induced osteoporosis on osseointegration could be ameliorated by the biomaterial's surface topography. Furthermore, gene expression analysis suggests this may be a result of enhanced osteogenic cell differentiation on the implant surface. Copyright © 2016 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

Simulations of chemical vapor deposition diamond film growth using a kinetic Monte Carlo model and two-dimensional models of microwave plasma and hot filament chemical vapor deposition reactors

NASA Astrophysics Data System (ADS)

May, P. W.; Harvey, J. N.; Allan, N. L.; Richley, J. C.; Mankelevich, Yu. A.

2010-12-01

A one-dimensional kinetic Monte Carlo (KMC) model has been developed to simulate the chemical vapor deposition of a diamond (100) surface under conditions used to grow single-crystal diamond (SCD), microcrystalline diamond (MCD), nanocrystalline diamond (NCD), and ultrananocrystalline diamond (UNCD) films. The model considers adsorption, etching/desorption, lattice incorporation and surface migration but not defect formation or renucleation processes. Two methods have been devised for estimation of the gas phase concentrations of species at the growing diamond surface, and are used to determine adsorption rates for C1Hx hydrocarbons for the different conditions. The rate of migration of adsorbed carbon species is governed by the availability of neighboring radical sites, which, in turn, depend upon the rates of H abstraction and of surface-radical migration. The KMC model predicts growth rates and surface roughness for each of diamond types consistent with experiment. In the absence of defect formation and renucleation the average surface diffusion length, ℓ, is a key parameter controlling surface morphology. When ℓ <2, surface migration is limited by the lack of availability of surface radical sites, and the migrating surface species simply hop back and forth between two adjacent sites but do not travel far beyond their initial adsorption site. Thus, Eley-Rideal processes dominate the growth, leading to the rough surfaces seen in NCD and UNCD. The maximum or "intrinsic" surface roughness occurs for nominally zero-migration conditions (ℓ =0) with an rms value of approximately five carbon atoms. Conversely, when migration occurs over greater distances (ℓ >2), Langmuir-Hinshelwood processes dominate the growth producing the smoother surfaces of MCD and SCD. By extrapolation, we predict that atomically smooth surfaces over large areas should occur once migrating species can travel approximately five sites (ℓ ˜5). β-scission processes are found to be unimportant for MCD and SCD growth conditions, but can remove up to 5% of the adsorbing carbon for NCD and UNCD growth. C1Hx insertion reactions also contribute <1% to the growth for nearly all conditions, while C2Hx (x <2) insertion reactions are negligible due their very low concentrations at the surface. Finally, the predictions for growth rate and morphology for UNCD deposition in a microwave system were found to be anomalous compared to those for all the other growth conditions, suggesting that carbonaceous particulates created in these plasmas may significantly affect the gas chemistry.

A Biochemical and Morphological Study of Rat Liver Microsomes

PubMed Central

Moulé, Y.; Rouiller, C.; Chauveau, J.

1960-01-01

Microsomes isolated by differential centrifugation from a rat liver homogenate in 0.88 M sucrose solution have been studied from the biochemical and morphological point of view. 1. Under these experimental conditions, the "total microsome" fraction was obtained by centrifuging the cytoplasmic extract free of nuclei and mitochondria, for 3 hours at 145,000 g. Morphologically, the total microsomes consist mainly of "rough-surfaced membranes" and "smooth" ones. 2. The total microsomes have been divided into 2 subfractions so that the 1st microsomal fraction contains the "rough" vesicles (2 hours centrifugation at 40,000 g) while the 2nd microsomal fraction consists essentially of smooth vesicles, free particles, and ferritin (centrifugation of the supernatant at 145,000 g for 3 hours). 3. By the action of 0.4 per cent sodium deoxycholate in 0.88 M sucrose, it was possible to obtain a pellet for each of the 2 fractions which consisted of dense particles, rich in RNA, poor in lipids, and which represented about 50 to 60 percent of the RNA and 10 to 15 per cent of the proteins. The results have been discussed taking into consideration the hypothesis of the presence of RNA in the membranes of microsomal vesicles. PMID:14424705

Polyimide surface modification by using microwave plasma for adhesion enhancement of Cu electroless plating.

PubMed

Cho, Sang-Jin; Nguyen, Trieu; Boo, Jin-Hyo

2011-06-01

Microwave (MW) plasma was applied to the surface of polyimide (PI) films as a treatment to enhance the adhesion between copper deposition layer and PI surface for electroless plating. The influences of nitrogen MW plasma treatment on chemical composition of the PI surface were investigated by using X-Ray photoelectron spectroscopy (XPS). The wettability was also investigated by water contact angle measurement. The surface morphologies of PI films before and after treatment were characterized with atomic force microscopy (AFM). The contact angle results show that was dramatically decreased to 16.1 degrees at the optimal treatment condition from 72.1 degrees (untreated PI). However, the root mean square (RMS) roughness of treated PI film was almost unchanged. The AFM roughness was stayed from 1.0 to 1.2 with/without plasma treatment. XPS data show a nitrogen increase when PI films exposed to N2 MW plasma. Electroless copper depositions were carried out with the free-formaldehyde method using glyoxylic acid as the reducing reagent and mixture palladium chloride, tin chloride as activation solution. Adhesion property between polyimide surface and copper layer was investigated by tape test.

Fabrication of nano-structured super-hydrophobic film on aluminum by controllable immersing method

NASA Astrophysics Data System (ADS)

Wu, Ruomei; Liang, Shuquan; Pan, Anqiang; Yuan, Zhiqing; Tang, Yan; Tan, Xiaoping; Guan, Dikai; Yu, Ya

2012-06-01

Aluminum alloy surface can be etched easily in acid environment, but the microstructure of alloy surface hardly meets the customers' demand. In this work, a facile acidic-assistant surface oxidation technique has been employed to form reproducible super-hydrophobic surfaces on aluminum alloy plates. The samples immersed in three different acid solutions at ambient temperatures are studied and the results demonstrated that the aqueous mixture solution of oxalic acid and hydrochloric is easier to produce better faces and better stability. Scanning electron microscopy (SEM), X-ray diffraction (XRD), Raman spectrometer, X-ray photoelectron spectroscopy (XPS) and water contact angle measurement are used to investigate the morphologies, microstructures, chemical compositions and hydrophobicity of the produced films on aluminum substrates. The surfaces, configured of a labyrinth structure with convexity and concavity, are in different roughness and gloss because of the different recipe acid solutions used. Better roughness of the surface can be obtained by adjusting the concentration of Clˉ and oxalate ions in acid solutions. The present research work provides a new strategy for the controllable preparation super-hydrophobic films of general materials on aluminum alloy for practical industrial applications.

Fast modification on wheat straw outer surface by water vapor plasma and its application on composite material.

PubMed

Chen, Weimin; Xu, Yicheng; Shi, Shukai; Cao, Yizhong; Chen, Minzhi; Zhou, Xiaoyan

2018-02-02

The presence of non-poplar extracts, cutin, and wax layer in the wheat straw outer surface (WOS) greatly limit its application in bio-composite preparation. In this study, a dielectric-barrier-discharge plasma using water vapor as feeding gas was used to fast modify the WOS. The morphology, free radical concentrations, surface chemical components, and contact angles of WOS before and after plasma modification were investigated. Wheat straw was further prepared into wheat straw-based composites (WSC) and its bonding strength was evaluated by a paper tension meter. The results showed that water vapor plasma leads to the appearance of surface roughness, the generation of massive free radicals, and the introduction of oxygen-containing groups. In addition, both initial and equilibrium contact angle and the surface total free energy were significantly increased after plasma modification. These results synergistically facilitate the spread and permeation of adhesive onto the WOS and thus improve the bonding strength of all prepared WSCs. A good linear relationship between bonding strength and surface roughness parameters, contact angles, and total free energy were observed. In general, this study provided a time-saving and cost-effective modification method to realize WSC manufacture.

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

NASA Astrophysics Data System (ADS)

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

2018-05-01

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

The effect of composition and thermodynamics on the surface morphology of durable superhydrophobic polymer coatings

PubMed Central

Nahum, Tehila; Dodiuk, Hanna; Kenig, Samuel; Panwar, Artee; Barry, Carol; Mead, Joey

2017-01-01

Durable superhydrophobic coatings were synthesized using a system of silica nanoparticles (NPs) to provide nanoscale roughness, fluorosilane to give hydrophobic chemistry, and three different polymer binders: urethane acrylate, ethyl 2-cyanoacrylate, and epoxy. Coatings composed of different binders incorporating NPs in various concentrations exhibited different superhydrophobic attributes when applied on polycarbonate (PC) and glass substrates and as a function of coating composition. It was found that the substrate surface characteristics and wettability affected the superhydrophobic characteristics of the coatings. Interfacial tension and spreading coefficient parameters (thermodynamics) of the coating components were used to predict the localization of the NPs for the different binders’ concentrations. The thermodynamic analysis of the NPs localization was in good agreement with the experimental observations. On the basis of the thermodynamic analysis and the experimental scanning electron microscopy, X-ray photoelectron spectroscopy, profilometry, and atomic force microscopy results, it was concluded that localization of the NPs on the surface was critical to provide the necessary roughness and resulting superhydrophobicity. The durability evaluated by tape testing of the epoxy formulations was the best on both glass and PC. Several coating compositions retained their superhydrophobicity after the tape test. In summary, it was concluded that thermodynamic analysis is a powerful tool to predict the roughness of the coating due to the location of NPs on the surface, and hence can be used in the design of superhydrophobic coatings. PMID:28243071

The effect of composition and thermodynamics on the surface morphology of durable superhydrophobic polymer coatings.

PubMed

Nahum, Tehila; Dodiuk, Hanna; Kenig, Samuel; Panwar, Artee; Barry, Carol; Mead, Joey

2017-01-01

Durable superhydrophobic coatings were synthesized using a system of silica nanoparticles (NPs) to provide nanoscale roughness, fluorosilane to give hydrophobic chemistry, and three different polymer binders: urethane acrylate, ethyl 2-cyanoacrylate, and epoxy. Coatings composed of different binders incorporating NPs in various concentrations exhibited different superhydrophobic attributes when applied on polycarbonate (PC) and glass substrates and as a function of coating composition. It was found that the substrate surface characteristics and wettability affected the superhydrophobic characteristics of the coatings. Interfacial tension and spreading coefficient parameters (thermodynamics) of the coating components were used to predict the localization of the NPs for the different binders' concentrations. The thermodynamic analysis of the NPs localization was in good agreement with the experimental observations. On the basis of the thermodynamic analysis and the experimental scanning electron microscopy, X-ray photoelectron spectroscopy, profilometry, and atomic force microscopy results, it was concluded that localization of the NPs on the surface was critical to provide the necessary roughness and resulting superhydrophobicity. The durability evaluated by tape testing of the epoxy formulations was the best on both glass and PC. Several coating compositions retained their superhydrophobicity after the tape test. In summary, it was concluded that thermodynamic analysis is a powerful tool to predict the roughness of the coating due to the location of NPs on the surface, and hence can be used in the design of superhydrophobic coatings.

Wettability of Thin Silicate-Containing Hydroxyapatite Films Formed by RF-Magnetron Sputtering

NASA Astrophysics Data System (ADS)

Gorodzha, S. N.; Surmeneva, M. A.; Surmenev, R. A.; Gribennikov, M. V.; Pichugin, V. F.; Sharonova, A. A.; Pustovalova, A. A.; Prymack, O.; Epple, M.; Wittmar, A.; Ulbricht, M.; Gogolinskii, K. V.; Kravchuk, K. S.

2014-02-01

Using the methods of electron and atomic force microscopy, X-ray structural analysis and measurements of the wetting angle, the features of morphology, structure, contact angle and free surface energy of silicon-containing calcium-phosphate coatings formed on the substrates made from titanium VT1-0 and stainless steel 12Cr18Ni10Ti are investigated. It is shown that the coating - substrate system possesses bimodal roughness formed by the substrate microrelief and coating nanostructure, whose principal crystalline phase is represented by silicon-substituted hydroxiapatite with the size of the coherent scattering region (CSR) 18-26 nm. It is found out that the formation of a nanostructured coating on the surface of rough substrates makes them hydrophilic. The limiting angle of water wetting for the coatings formed on titanium and steel acquires the values in the following ranges: 90-92 and 101-104°, respectively, and decreases with time.

Electron-beam patterned self-assembled monolayers as templates for Cu electrodeposition and lift-off.

PubMed

She, Zhe; Difalco, Andrea; Hähner, Georg; Buck, Manfred

2012-01-01

Self-assembled monolayers (SAMs) of 4'-methylbiphenyl-4-thiol (MBP0) adsorbed on polycrystalline gold substrates served as templates to control electrochemical deposition of Cu structures from acidic solution, and enabled the subsequent lift-off of the metal structures by attachment to epoxy glue. By exploiting the negative-resist behaviour of MBP0, the SAM was patterned by means of electron-beam lithography. For high deposition contrast a two-step procedure was employed involving a nucleation phase around -0.7 V versus Cu(2+)/Cu and a growth phase at around -0.35 V versus Cu(2+)/Cu. Structures with features down to 100 nm were deposited and transferred with high fidelity. By using substrates with different surface morphologies, AFM measurements revealed that the roughness of the substrate is a crucial factor but not the only one determining the roughness of the copper surface that is exposed after lift-off.

Effect of applied voltage on surface properties of anodised titanium in mixture of β-glycerophosphate (β-GP) and calcium acetate (CA)

NASA Astrophysics Data System (ADS)

Chuan, Lee Te; Rathi, Muhammad Fareez Mohamad; Abidin, Muhamad Yusuf Zainal; Abdullah, Hasan Zuhudi; Idris, Maizlinda Izwana

2015-07-01

Anodic oxidation is a surface modification method which combines electric field driven metal and oxygen ion diffusion for formation of oxide layer on the anode surface. This method has been widely used to modify the surface morphology of biomaterial especially titanium. This study aimed to investigate the effect of applied voltage on titanium. Specifically, the titanium foil was anodised in mixture of β-glycerophosphate disodium salt pentahydrate (β-GP) and calcium acetate monohydrate (CA) with different applied voltage (50-350 V), electrolyte concentration (0.04 M β-GP + 0.4 M CA), anodising time (10minutes) and current density (50 and 70 mA.cm-2) at room temperature. Surface oxide properties of anodised titanium were characterised by digital single-lens reflex camera (DSLR camera), field emission scanning electron microscope (FESEM) and atomic force microscopy (AFM). At lower applied voltage (≤150 V), surface of titanium foils were relatively smooth. With increasing applied voltage (≥250 V), the oxide layer became more porous and donut-shaped pores were formed on the surface of titanium foils. The AFM results indicated that the surface roughness of anodised titanium increases with increasing of applied voltage. The porous and rough surface is able to promote the osseointegration and reduce the suffering time of patient.

Homoepitaxial growth of β-Ga{sub 2}O{sub 3} thin films by low pressure chemical vapor deposition

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

Rafique, Subrina; Han, Lu; Zhao, Hongping, E-mail: hongping.zhao@case.edu

2016-05-02

This paper presents the homoepitaxial growth of phase pure (010) β-Ga{sub 2}O{sub 3} thin films on (010) β-Ga{sub 2}O{sub 3} substrate by low pressure chemical vapor deposition. The effects of growth temperature on the surface morphology and crystal quality of the thin films were systematically investigated. The thin films were synthesized using high purity metallic gallium (Ga) and oxygen (O{sub 2}) as precursors for gallium and oxygen, respectively. The surface morphology and structural properties of the thin films were characterized by atomic force microscopy, X-ray diffraction, and high resolution transmission electron microscopy. Material characterization indicates the growth temperature played anmore » important role in controlling both surface morphology and crystal quality of the β-Ga{sub 2}O{sub 3} thin films. The smallest root-mean-square surface roughness of ∼7 nm was for thin films grown at a temperature of 950 °C, whereas the highest growth rate (∼1.3 μm/h) with a fixed oxygen flow rate was obtained for the epitaxial layers grown at 850 °C.« less

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.

Mechanical properties and superficial characterization of a milled CAD-CAM glass fiber post.

PubMed

Ruschel, George Hebert; Gomes, Érica Alves; Silva-Sousa, Yara Terezinha; Pinelli, Rafaela Giedra Pirondi; Sousa-Neto, Manoel Damião; Pereira, Gabriel Kalil Rocha; Spazzin, Aloísio Oro

2018-06-01

Computer-aided design and computer-aided manufacturing (CAD-CAM) technology may be used to produce custom intraradicular posts, but studies are lacking. The purpose of this in vitro study was to evaluate the flexural properties (strength and modulus), failure mode, superficial morphology, and roughness of two CAD-CAM glass fiber posts (milled at different angulations) compared with a commercially available prefabricated glass fiber post. Three groups were tested (n = 10): PF (control group)- prefabricated glass fiber post; C-Cd-diagonally milled post; and C-Cv-vertically milled post. A 3-dimensional virtual image was obtained from a prefabricated post, which guided the posterior milling of posts from a glass fiber disk (Trilor Blanks; Bioloren). Surface roughness and morphology were evaluated using confocal laser microscopy. Flexural strength and modulus were evaluated with the 3-point bend test. Data were submitted to one-way analysis of variance followed by the Student-Newman-Keuls post hoc test (α = 0.05). The fractured surfaces were evaluated with scanning electron microscopy. The superficial roughness was highest for PF and similar for the experimental groups. Morphological analysis shows different sizes and directions of the glass fibers along the post. The flexural strength was highest for PF (900.1 ± 30.4 > C-Cd - 357.2 ± 30.7 > C-Cv 101.8 ± 4.3 MPa) as was the flexural modulus (PF 19.3 ± 2.0 GPa > C-Cv 10.1 ± 1.9 GPa > C-Cd 7.8 ± 1.3 GPa). A CAD-CAM milled post seems a promising development, but processing requires optimizing, as the prefabricated post still shows better mechanical properties and superficial characteristics. Copyright © 2018 Elsevier Ltd. All rights reserved.

The influence of a novel in-office tooth whitening procedure using an Er,Cr:YSGG laser on enamel surface morphology.

PubMed

Dionysopoulos, Dimitrios; Strakas, Dimitrios; Koliniotou-Koumpia, Eugenia

2015-08-01

The purpose of this in vitro study was to evaluate the influence of a novel in-office tooth whitening procedure using Er,Cr:YSGG laser radiation on bovine enamel. Forty-eight enamel specimens were prepared from bovine canines and divided into four groups: Group 1 specimens (control) received no whitening treatment; Group 2 received whitening treatment with an at-home whitening agent (22% carbamide peroxide) for 7 days; Group 3 received whitening treatment with a novel in-office whitening agent (35% H(2)O(2)); Group 4 received the same in-office whitening therapy with Group 3 using Er,Cr:YSGG laser in order to accelerate the whitening procedure. The specimens were stored for 10 days after the whitening treatment in artificial saliva. Vickers hardness was determined using a microhardness tester and surface roughness was evaluated using a VSI microscope. Three specimens of each experimental group were examined under SEM and the mineral composition of the specimens was evaluated using EDS. Data were statistically analyzed using one-way ANOVA, Tukey's post-hoc test, Wilcoxon signed rank and Kruskal-Wallis tests (a = 0.05). The surface microhardness of the enamel was reduced after the in-office whitening treatments (P< 0.05), but not influenced after the at-home whitening treatment (P> 0.05). Moreover, the surface roughness was not significantly changed after tooth whitening. EDS analysis did not show alterations in the enamel mineral composition, while SEM observations indicated changes in the surface morphology, especially after in-office tooth whitening (P< 0.05). The laser-assisted whitening treatment with Er,Cr:YSGG laser did not affect the alterations in enamel surface compared with the conventional in-office whitening technique. © 2015 Wiley Periodicals, Inc.

Quantitative Prediction of Stone Fragility From Routine Dual Energy CT: Ex vivo proof of Feasibility.

PubMed

Ferrero, Andrea; Montoya, Juan C; Vaughan, Lisa E; Huang, Alice E; McKeag, Ian O; Enders, Felicity T; Williams, James C; McCollough, Cynthia H

2016-12-01

Previous studies have demonstrated a qualitative relationship between stone fragility and internal stone morphology. The goal of this study was to quantify morphologic features from dual-energy computed tomography (CT) images and assess their relationship to stone fragility. Thirty-three calcified urinary stones were scanned with micro-CT. Next, they were placed within torso-shaped water phantoms and scanned with the dual-energy CT stone composition protocol in routine use at our institution. Mixed low- and high-energy images were used to measure volume, surface roughness, and 12 metrics describing internal morphology for each stone. The ratios of low- to high-energy CT numbers were also measured. Subsequent to imaging, stone fragility was measured by disintegrating each stone in a controlled ex vivo experiment using an ultrasonic lithotripter and recording the time to comminution. A multivariable linear regression model was developed to predict time to comminution. The average stone volume was 300 mm 3 (range: 134-674 mm 3 ). The average comminution time measured ex vivo was 32 seconds (range: 7-115 seconds). Stone volume, dual-energy CT number ratio, and surface roughness were found to have the best combined predictive ability to estimate comminution time (adjusted R 2  = 0.58). The predictive ability of mixed dual-energy CT images, without use of the dual-energy CT number ratio, to estimate comminution time was slightly inferior, with an adjusted R 2 of 0.54. Dual-energy CT number ratios, volume, and morphologic metrics may provide a method for predicting stone fragility, as measured by time to comminution from ultrasonic lithotripsy. Copyright © 2016 The Association of University Radiologists. Published by Elsevier Inc. All rights reserved.

Quantitative prediction of stone fragility from routine single and dual energy CT: proof of feasibility

PubMed Central

Ferrero, Andrea; Montoya, Juan C.; Vaughan, Lisa E.; Huang, Alice E.; McKeag, Ian O.; Enders, Felicity T.; Williams, James C.; McCollough, Cynthia H.

2016-01-01

Rationale and Objectives Previous studies have demonstrated a qualitative relationship between stone fragility and internal stone morphology. The goal of this study was to quantify morphological features from dual-energy CT images and assess their relationship to stone fragility. Materials and Methods Thirty-three calcified urinary stones were scanned with micro CT. Next, they were placed within torso-shaped water phantoms and scanned with the dual-energy CT stone composition protocol in routine use at our institution. Mixed low-and high-energy images were used to measure volume, surface roughness, and 12 metrics describing internal morphology for each stone. The ratios of low- to high-energy CT numbers were also measured. Subsequent to imaging, stone fragility was measured by disintegrating each stone in a controlled ex vivo experiment using an ultrasonic lithotripter and recording the time to comminution. A multivariable linear regression model was developed to predict time to comminution. Results The average stone volume was 300 mm3 (range 134–674 mm3). The average comminution time measured ex vivo was 32 s (range 7–115 s). Stone volume, dual-energy CT number ratio and surface roughness were found to have the best combined predictive ability to estimate comminution time (adjusted R2= 0.58). The predictive ability of mixed dual-energy CT images, without use of the dual-energy CT number ratio, to estimate comminution time was slightly inferior, with an adjusted R2 of 0.54. Conclusion Dual-energy CT number ratios, volume, and morphological metrics may provide a method for predicting stone fragility, as measured by time to comminution from ultrasonic lithotripsy. PMID:27717761

Modification of surface morphology of Ti6Al4V alloy manufactured by Laser Sintering

NASA Astrophysics Data System (ADS)

Draganovská, Dagmar; Ižariková, Gabriela; Guzanová, Anna; Brezinová, Janette; Koncz, Juraj

2016-06-01

The paper deals with the evaluation of relation between roughness parameters of Ti6Al4V alloy produced by DMLS and modified by abrasive blasting. There were two types of blasting abrasives that were used - white corundum and Zirblast at three levels of air pressure. The effect of pressure on the value of individual roughness parameters and an influence of blasting media on the parameters for samples blasted by white corundum and Zirblast were evaluated by ANOVA. Based on the measured values, the correlation matrix was set and the standard of correlation statistic importance between the monitored parameters was determined from it. The correlation coefficient was also set.

The Effect of Cutting Speed in Metallic Glass Grinding

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

Serbest, Erdinc; Bakkal, Mustafa; Karipcin, Ilker

2011-01-17

In this paper, the effects of the cutting speed in metallic glass grinding were investigated in dry conditions. The results showed that grinding forces decrease as grinding energy increase with the increasing cutting speeds. The present investigations on ground surface and grinding chips morphologies -shows that material removal and surface formation of the BMG are mainly due to the ductile chip deformation and ploughing as well as brittle fracture of some particles from the edges of the tracks. The roughness values obtained with the Cubic Boron Nitride wheels are acceptable for the grinding operation.

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

Lyazgin, Alexander, E-mail: lyazgin@list.ru; Shugurov, Artur, E-mail: shugurov@ispms.tsc.ru; Sergeev, Viktor, E-mail: retc@ispms.tsc.ru

The effect of bombardment of the Ni-B sublayer by Zr ion beams on the surface morphology and tribomechanical properties of Au-Ni coatings was investigated. It was found that the treatment has no significant effect on the surface roughness and grain size of the Au-Ni coatings, while it provides essential reducing of their friction coefficient and improvement of wear resistance. It is shown that increased wear resistance of these coatings was caused by their strain hardening resulted from localization of plastic strain. The optimal Zr fluence were determined that provide the maximum reduction of linear wear of the coatings.

Shape evolution of a core-shell spherical particle under hydrostatic pressure.

PubMed

Colin, Jérôme

2012-03-01

The morphological evolution by surface diffusion of a core-shell spherical particle has been investigated theoretically under hydrostatic pressure when the shear modulii of the core and shell are different. A linear stability analysis has demonstrated that depending on the pressure, shear modulii, and radii of both phases, the free surface of the composite particle may be unstable with respect to a shape perturbation. A stability diagram finally emphasizes that the roughness development is favored in the case of a hard shell with a soft core.

Ag-ZnO nanostructure for ANTA explosive molecule detection

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

Shaik, Ummar Pasha; Sangani, L. D. Varma; Gaur, Anshu

2016-05-23

Ag/ZnO nanostructure for surface enhanced Raman scattering application in the detection of ANTA explosive molecule is demonstrated. A highly rough ZnO microstructure was achieved by rapid thermal annealing of metallic Zn film. Different thickness Ag nanostructures are decorated over these ZnO microstructures by ion beam sputtering technique. Surface enhanced Raman spectroscopic studies carried out over Ag/ZnO substrates have shown three orders higher enhancement compared to bare Ag nanostructure deposited on the same substrate. The reasons behind such huge enhancement are discussed based on the morphology of the sample.

Ni-P/Zn-Ni compositionally modulated multilayer coatings - Part 1: Electrodeposition and growth mechanism, composition, morphology, roughness and structure

NASA Astrophysics Data System (ADS)

Bahadormanesh, Behrouz; Ghorbani, Mohammad

2018-06-01

The Ni-P/Zn-Ni compositionally modulated multilayer coatings CMMCs were electrodeposited from a single bath by switching the cathodic current density. The composition, surface morphology, roughness, layers growth pattern as well as the phase structure of deposits were extensively studied via SEM, EDS, AFM and XRD analysis. Effects of bath ingredients on the electrodeposition behavior were analyzed through cathodic linear sweep voltammetry. Although the concentration of Zn2+ in bath was 13 times higher than Ni2+, the Zn-Ni deposition potential was much nearer to Ni deposition potential rather than that of Zn. Addition of NaH2PO2 to the Ni deposition bath considerably raised the current density and shifted the crystallization potential of Ni to more nobble values. Codeposition of P with Zn-Ni alloy lead to crack formation in the monolayer that was deposited in 60 mA/cm2. However, the cracks were not observed in the Zn-Ni layers of multilayers. Zn-Ni layers in CMMCs exhibited a three-dimensional pattern of growth while that of Ni-P layers was two-dimensional. Also, the Ni-P deposits tends to fill the discontinuities in Zn-Ni layers and performed leveling properties and lowered the surface roughness of Zn-Ni layers and CMMCs. Structural analysis demonstrated that Ni-P layers were amorphous and the Zn-Ni layers exhibited crystallite phase of Zn11Ni2. Thus, the Ni-P/Zn-Ni CMMCs comprised of alternate layers of amorphous Ni-P and nanocrystalline Zn Ni.

Correlation of film morphology and defect content with the charge-carrier transport in thin-film transistors based on ZnO nanoparticles

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

Polster, S.; Jank, M. P. M.; Frey, L.

2016-01-14

The correlation of defect content and film morphology with the charge-carrier transport in field-effect devices based on zinc oxide nanoparticles was investigated. Changes in the defect content and the morphology were realized by annealing and sintering of the nanoparticle thin films. Temperature-dependent electrical measurements reveal that the carrier transport is thermally activated for both the unsintered and sintered thin films. Reduced energetic barrier heights between the particles have been determined after sintering. Additionally, the energetic barrier heights between the particles can be reduced by increasing the drain-to-source voltage and the gate-to-source voltage. The changes in the barrier height are discussedmore » with respect to information obtained by scanning electron microscopy and photoluminescence measurements. It is found that a reduction of surface states and a lower roughness at the interface between the particle layer and the gate dielectric lead to lower barrier heights. Both surface termination and layer morphology at the interface affect the barrier height and thus are the main criteria for mobility improvement and device optimization.« less

Effect of Sequence Blockiness on the Morphologies of Surface-grafted Elastin-like Polypeptides

NASA Astrophysics Data System (ADS)

Albert, Julie; Sintavanon, Kornkanok; Mays, Robin; MacEwan, Sarah; Chilkoti, Ashutosh; Genzer, Jan

2014-03-01

The inter- and intra- molecular interactions among monomeric units of copolymers and polypeptides depend strongly on monomer sequence distribution and dictate the phase behavior of these species both in solution and on surfaces. To study the relationship between sequence and phase behavior, we have designed a series of elastin-like polypeptides (ELPs) with controlled monomer sequences that mimic copolymers with various co-monomer sequence distributions and attached them covalently to silicon substrates from buffer solutions at temperatures below and above the bulk ELPs' lower critical solution temperatures (LCSTs). The dependence of ELP grafting density on solution temperature was examined by ellipsometry and the resultant surface morphologies were examined in air and under water with atomic force microscopy. Depositions performed above the LCST resulted in higher grafting densities and greater surface roughness of ELPs relative to depositions carried out below the LCST. In addition, we are using gradient substrates to examine the effect of ELP grafting density on temperature responsiveness.

Interrelation of the construction of the metamorphic InAlAs/InGaAs nanoheterostructures with the InAs content in the active layer of 76-100% with their surface morphology and electrical properties

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

Vasil'evskii, I. S., E-mail: ivasilevskii@mail.ru; Galiev, G. B.; Klimov, E. A.

The influence of the construction of a metamorphic buffer on the surface morphology and electrical properties of InAlAs/InGaAs/InAlAs nanoheterostructures with InAs content in the active layer from 76 to 100% with the use of the GaAs and InP substrates is studied. It is shown that such parameters as the electron mobility and the concentration, as well as the root-mean-square surface roughness, substantially depend on the construction of the metamorphic buffer. It is established experimentally that these parameters largely depend on the maximal local gradient of the lattice constant of the metamorphic buffer in the growth direction of the layers rathermore » than on its average value. It is shown that, with selection of the construction of the metamorphic buffer, it is possible to form nanostructured surfaces with a large-periodic profile.« less

Surface self-organization in multilayer film coatings

NASA Astrophysics Data System (ADS)

Shuvalov, Gleb M.; Kostyrko, Sergey A.

2017-12-01

It is a recognized fact that during film deposition and subsequent thermal processing the film surface evolves into an undulating profile. Surface roughness affects many important aspects in the engineering application of thin film materials such as wetting, heat transfer, mechanical, electromagnetic and optical properties. To accurately control the morphological surface modifications at the micro- and nanoscale and improve manufacturing techniques, we design a mathematical model of the surface self-organization process in multilayer film materials. In this paper, we consider a solid film coating with an arbitrary number of layers under plane strain conditions. The film surface has a small initial perturbation described by a periodic function. It is assumed that the evolution of the surface relief is governed by surface and volume diffusion. Based on Gibbs thermodynamics and linear theory of elasticity, we present a procedure for constructing a governing equation that gives the amplitude change of the surface perturbation with time. A parametric study of the evolution equation leads to the definition of a critical undulation wavelength that stabilizes the surface. As a numerical result, the influence of geometrical and physical parameters on the morphological stability of an isotropic two-layered film coating is analyzed.

Effects of sterilisation method on surface topography and in-vitro cell behaviour of electrostatically spun scaffolds.

PubMed

Andrews, Kirstie D; Hunt, John A; Black, Richard A

2007-02-01

Electrostatic spinning is a potentially significant technique for scaffold production within the field of tissue engineering; however, the effect of sterilisation upon these structures is not known. This research investigated the extent of any topographical alteration to electrostatically spun scaffolds post-production through sterilisation, and examined any subsequent effect on contacting cells. Scaffolds made from Tecoflex SG-80A polyurethane were sterilised using ethylene oxide and UV-ozone. Scaffold topography was characterized in terms of inter-fibre separation (ifs), fibre diameter (f.dia) and surface roughness. Cell culture was performed over 7 days with both mouse L929 and human embryonic lung fibroblasts, the results of which were assessed using SEM, image analysis and confocal microscopy. Sterilisation by UV-ozone and ethylene oxide decreased ifs and increased f.dia; surface roughness was decreased by UV-ozone but increased by ethylene oxide. Possible mechanisms to explain these observations are discussed, namely photo-oxidative degradation in the case of UV-ozone and process-induced changes in surface roughness. UV-ozone sterilised scaffolds showed greater cell coverage than those treated with ethylene oxide, but lower coverage than all the controls. Changes in cell attachment and morphology were thought to be due to the changes in topography brought about by the sterilisation process. We conclude that surface modification by sterilisation could prove to be a useful tool at the final stage of scaffold production to enhance cell contact, phenotype or function.

Morphology, stratigraphy, and surface roughness properties of Venusian lava flow fields

NASA Astrophysics Data System (ADS)

Byrnes, Jeffrey M.; Crown, David A.

2002-10-01

Morphologic characteristics, flow stratigraphy, and radar backscatter properties of five lava flow fields on Venus (Turgmam Fluctus, Zipaltonal Fluctus, Tuli Mons/Uilata Fluctus, Var Mons, and Mylitta Fluctus) were examined to understand flow field emplacement mechanisms and relationships to other surface processes. These analyses indicate that the flow fields studied developed through emplacement of numerous, thin flow units, presumably over extended periods of time. Although the Venusian fields display flow morphologies similar to those observed within terrestrial flow fields, the Venusian flow units are significantly larger and have a larger range of radar backscatter coefficients. Both simple and compound flow emplacement appear to have occurred within the flow fields. A potential correlation between flow rheology and radar brightness is suggested by differences in planform morphology, apparent flow thickness, and apparent sensitivity to topography between bright and dark flows. Distributary flow morphologies may result from tube-fed flows, and postemplacement modification by processes such as flow inflation and crustal foundering is consistent with discrete zones of increased radar brightness within individual flow lobes. Mapping of these flow fields does not indicate any simple evolutionary trend in eruptive/resurfacing style within the flow fields, or any consistent temporal sequence relative to other tectonic and volcanic features.

Effects of atmospheric air plasma treatment on interfacial properties of PBO fiber reinforced composites

NASA Astrophysics Data System (ADS)

Zhang, Chengshuang; Li, Cuiyun; Wang, Baiya; Wang, Bin; Cui, Hong

2013-07-01

Poly(p-phenylene benzobisoxazole) (PBO) fiber was modified by atmospheric air plasma treatment. The effects of plasma treatment power and speed on both surface properties of PBO fibers and interfacial properties of PBO/epoxy composites were investigated. Surface chemical composition of PBO fibers were analyzed by X-ray photoelectron spectroscopy (XPS). Surface morphologies of the fibers and interface structures of the composites were examined using scanning electron microscopy (SEM). Interfacial adhesion property of the composites was evaluated by interlaminar shear strength (ILSS). Mechanical properties of PBO multifilament were measured by universal testing machine. The results indicate that atmospheric air plasma treatment introduced some polar or oxygen-containing groups to PBO fiber surfaces, enhanced surface roughness and changed surface morphologies of PBO fibers by plasma etching and oxidative reactions. The plasma treatment also improved interfacial adhesion of PBO/epoxy composites but has little effect on tensile properties of PBO multifilament. The ILSS of PBO/epoxy composites increased to 40.0 MPa after atmospheric air plasma treatment with plasma treatment power of 300 W and treatment speed of 6 m/min.

The effect of particle morphology on the physical stability of pharmaceutical powder mixtures

NASA Astrophysics Data System (ADS)

Swaminathan, Vidya

Pharmaceutical powder mixtures are composed of particles that physically interact, precluding the formation of random mixtures. Mixtures based on particle interactions are termed ordered mixtures. The objective of this study was to determine the effect of the morphological characteristics of the components, surface texture and shape, along with size, on the formation of stable mixtures. Morphological parameters were obtained from image analysis measurements. Surface roughness was quantified using the ratio of the perimeter of the particle to that of an ideal shape (circle or square) having the same area; shape was described using the aspect ratio. The stability of mixtures of micronized aspirin with carriers of different surface roughness was determined by measuring the extent of drug adhering to the carrier after subjecting the mixtures to vibration. A lesser extent of segregation of drug from highly textured carriers relative to smoother textured carriers was observed. This was postulated to be due to a larger concentration of surface asperities on the coarser carriers which constitute potentially strong adhesion sites. The electrostatic charge on the powders was measured; differences in the response of the mixtures to the addition of magnesium stearate were attributed to electrostatic charge effects. The effect of varying the aspect ratio of the carrier and drug on segregation in polydisperse mixtures was determined from the coefficient of variation of the drug in the mixture as a function of mixing time. Reducing the size of the carrier resulted in poor homogeneity due to weak carrier-drug interactions. The variation in drug content resulting from a change in the shape of the carriers was smaller than that caused by size differences. The segregation rate constant in mixtures having dissimilarly shaped components was larger than in mixtures having components of similar shape. The effects of magnesium stearate concentration and lubrication time on the content uniformity of polydisperse mixtures were evaluated from a full factorial experiment. The segregation response of ordered and random mixtures to the addition of magnesium stearate was compared. The moisture sorption behavior of commercial magnesium stearate and the resulting morphological changes were evaluated.

Fabrication of TiO2 Crystalline Coatings by Combining Ti-6Al-4V Anodic Oxidation and Heat Treatments

PubMed Central

Schvezov, Carlos Enrique; Ares, Alicia Esther

2015-01-01

The bio- and hemocompatibility of titanium alloys are due to the formation of a TiO2 layer. This natural oxide may have fissures which are detrimental to its properties. Anodic oxidation is used to obtain thicker films. By means of this technique, at low voltages oxidation, amorphous and low roughness coatings are obtained, while, above a certain voltage, crystalline and porous coatings are obtained. According to the literature, the crystalline phases of TiO2, anatase, and rutile would present greater biocompatibility than the amorphous phase. On the other hand, for hemocompatible applications, smooth and homogeneous surfaces are required. One way to obtain crystalline and homogeneous coatings is by heat treatments after anodic oxidation. The aim of this study is to evaluate the influence of heat treatments on the thickness, morphology, and crystalline structure of the TiO2 anodic coatings. The characterization was performed by optical and scanning electron microscopy, X-ray diffraction, and X-ray reflectometry. Coatings with different colors of interference were obtained. There were no significant changes in the surface morphology and roughness after heat treatment of 500°C. Heat treated coatings have different proportions of the crystalline phases, depending on the voltage of anodic oxidation and the temperature of the heat treatment. PMID:25784939

Morphology Controls on Calcite Recrystallization.

PubMed

Heberling, Frank; Paulig, Leonie; Nie, Zhe; Schild, Dieter; Finck, Nicolas

2016-11-01

Environmental scientists and geoscientists working in different fields regard the reactivity of calcite and corresponding changes in its trace elemental- or isotopic composition from diametrically opposed points of view. As one extreme, calcite based environmental remediation strategies rely on the fast recrystallization of calcite and the concurrent uptake and immobilization of pollutants. Paleo-ecological investigations denote the other extreme, and rely on the invariability of calcite composition over geological periods of time. We use long-term radiotracer experiments to quantify recrystallization rates of seven types of calcite powder with diverse morphology and particle size distribution. On the one hand our results demonstrate the long-term metastability of calcite with equilibrated crystal surfaces even at isotopic dis-equilibrium. On the other hand, we document the extremely high reactivity and interfacial free energy of freshly ground, rough calcite. Our results indicate that bulk calcite recrystallization is an interfacial free energy driven Ostwald-ripening process, in which particle roughness effects dominate over the effect of crystal habitus and particle size. We confirm that the dynamic equilibrium exchange of crystal constituents between kink sites involves an activation barrier of about 25 kJ/mol. At room temperature the equilibrium exchange is limited to a near surface region and proceeds at a rate of (3.6 ± 1.4)·10 -13 mol/(m 2 ·s).

Graphene-Like 2D Porous Carbon Nanosheets Derived from Cornstalk Pith for Energy Storage Materials

NASA Astrophysics Data System (ADS)

Gao, Kezheng; Niu, Qingyuan; Tang, Qiheng; Guo, Yaqing; Wang, Lizhen

2018-01-01

Biomass materials from different organisms or different parts (even different periods) of the same organism have different microscopic morphologies, hierarchical pore structures and even elemental compositions. Therefore, carbon materials inheriting the unique hierarchical microstructure of different biomass materials may exhibit significantly different electrochemical properties. Cornstalk pith and cornstalk skin (dried by freeze-drying) exhibit significantly different microstructures due to their different biological functions. The cornstalk skin-based carbon (S-carbon) exhibits a thick planar morphology, and the Barrett-Emmett-Teller (BET) surface area is only about 332.07 m2 g-1. However, cornstalk pith-based carbon (P-carbon) exhibits a graphene-like 2D porous nanosheet structure with a rough, wrinkled morphology, and the BET surface area is about 805.17 m2 g-1. In addition, a P-carbon supercapacitor exhibits much higher specific capacitance and much better rate capability than an S-carbon supercapacitor in 6 M potassium hydroxide (KOH) electrolyte.

Raman study of bulk-heterojunction morphology in photoactive layers treated with solvent-vapor annealing

NASA Astrophysics Data System (ADS)

Onojima, Norio; Ishima, Yasuhisa; Izumi, Daisuke; Takahashi, Kazuyuki

2018-03-01

The effect of solvent-vapor annealing (SVA) on bulk-heterojunction morphology in photoactive layers composed of poly(3-hexylthiophene-2,5-diyl) (P3HT) and [6,6]-phenyl-C61-butyric acid methyl ester (PCBM) was analyzed using Raman spectroscopy. We prepared the photoactive layers by electrostatic spray deposition (ESD) and fabricated organic photovoltaic devices with a conventional cell structure. Although postdeposition annealing can be omitted when the photoactive layer is deposited using ESD under dry condition, the surface is relatively rough owing to the existence of a number of droplet traces. The SVA treatment can eliminate such droplet traces, while excessive SVA resulted in a significant decrease in open-circuit voltage. The Raman study of the bulk-heterojunction morphology demonstrated the accumulation of P3HT molecules on the surface during SVA, which induced the recombination of photogenerated charges at the interface of the cathode/photoactive layer and thereby decreased the open-circuit voltage.

Synergistic effect of wire bending and salivary pH on surface properties and mechanical properties of orthodontic stainless steel archwires.

PubMed

Hobbelink, Marieke G; He, Yan; Xu, Jia; Xie, Huixu; Stoll, Richard; Ye, Qingsong

2015-01-01

The aim of this study was to investigate the corrosive behaviour of stainless steel archwires in a more clinically relevant way by bending and exposing to various pH. One hundred and twenty pieces of rectangular stainless steel wires (0.43 × 0.64 mm) were randomly assigned into four groups. In each group, there were 15 pieces of bent wires and 15 straight ones. Prior to measurements of the wires, as individual experimental groups (group 1, 2, and 3), the wires were exposed to artificial saliva for 4 weeks at pH 5.6, 6.6, and 7.6, respectively. A control group of wires (group 4) remained in air for the same period of time before sent for measurements. Surface roughness (Ra-value) was measured by a profilometer. Young's modulus and maximum force were determined by a four-point flexural test apparatus. Scanning electron microscopy was used to observe the surface morphology of straight wire. Differences between groups were examined using a two-way analysis of variance (ANOVA). Mean surface roughness values, flexural Young's moduli, and maximum force values of bent wires are significantly different from those of the straight wires, which was the main effect of wire bending, ignoring the influence of pH. A significant effect was found between Ra-values regarding the main effect of pH, ignoring the influence of shape. There was a significant interaction effect of bending and pH on flexural Young's moduli of stainless steel archwires, while pH did not show much impact on the maximum force values of those stainless steel wires. Bigger surface irregularities were seen on SEM images of straight wires immersed in artificial saliva at pH 5.6 compared to artificial saliva at other pH values. Surface depth (Rz) was more sensitive than Ra in revealing surface roughness, both measured from 3D reconstructed SEM images. Ra showed a comparable result of surface roughness to Ra-value measured by the profilometer. Bending has a significant influence on surface roughness and mechanical properties of rectangular SS archwires. pH plays a synergistic effect on the change of mechanical properties of stainless steel (SS) wires along with wire bending.

Remineralization of early enamel caries lesions using different bioactive elements containing toothpastes: An in vitro study.

PubMed

Wang, Yu; Mei, Li; Gong, Lin; Li, Jialing; He, Shaowei; Ji, Yan; Sun, Weibin

2016-09-14

Demineralization can be arrested or reversed when remineralization agents are applied to incipient carious or non-cavitated carious lesions. A large number of therapeutic agents including non-fluoridated products have been developed to promote enamel remineralization. This study aims to evaluate the efficacy of different bioactive elements containing toothpastes in remineralization of artificial enamel lesions. Artificial carious lesions were created on 40 human enamel slabs, and were randomly divided into four groups: (1) control group (no treatment), (2) casein phosphopeptide-amorphous calcium phosphate group (CPP-ACP, GC Tooth Mousse), (3) 8% arginine and calcium carbonate group (ACC, Colgate Sensitive Pro-Relief), (4) calcium sodium phosphosilicate group (CSP, NovaMin®). All samples were subjected to 15 days of pH-cycling. Subsequently, a one-hour acid resistance test was carried out. Surface hardness of the samples was assessed using the Knoop hardness test, and surface morphology and roughness were assessed by scanning electron microscopy (SEM) and atomic force microscopy (AFM). Data were analyzed using one-way ANOVA, Tukey's test and paired t test. The three tested toothpastes exhibited a significantly higher remineralization efficacy compared with the control group (P< 0.05 for all). After pH-cycling, the specimens treated with Colgate Sensitive Pro-Relief and NovaMin® showed a significant higher surface hardness (P< 0.001 and P= 0.03, respectively) and lower surface roughness (P< 0.05 for both) compared those treated with GC Tooth Mousse. While after the acid resistance test, all groups showed a significant loss of surface hardness (P< 0.001 for all) and significant increase of surface roughness (P< 0.05). The specimens treated with Colgate Sensitive Pro-Relief and NovaMin® still showed a significant higher surface hardness and lower surface roughness in comparison with those treated with GC Tooth Mousse (P< 0.05 for all). No significant difference was found in surface hardness and roughness between Colgate Sensitive Pro-Relief and NovaMin® during the pH-cycling test and acid resistance test (P= 0.45 and P= 0.83, respectively). Colgate Sensitive Pro-Relief and NovaMin® present an advantage in enhancing remineralization and inhibiting demineralization for early enamel carious lesions in comparison with GC Tooth Mousse.

Evaluation of Surface Roughness of Ceramic and Resin Composite Material Used for Conservative Indirect Restorations, after Repolishing by Intraoral Means.

PubMed

Vrochari, Areti D; Petropoulou, Aikaterini; Chronopoulos, Vasilios; Polydorou, Olga; Massey, Ward; Hellwig, Elmar

2017-06-01

To evaluate and compare the mean surface roughness (Ra) of one ceramic and one resin composite material used for indirect restorations, after grinding and repolishing by intraoral means. The materials used were the lithium disilicate glass ceramic IPS e.max Press (EMP) and the indirect resin composite restoration system Gradia (GR). Twelve specimen disks were prepared from each material according to the manufacturer of each material. Five initial measurements of the Ra (Ra 1 ) were made on each specimen as a referral basis, and the specimens were ground with a fine (red) diamond bur. The specimens were repolished using (a) Komet Dialite Polishing Kit for EMP and (b) Enhance Finishing and Polishing System and Prisma Gloss Polishing Paste for GR. Five final Ra (Ra 2 ) measurements were performed on each specimen. All measurements were made using a laser profilometer. Scanning electron microscopy (SEM) was also used to visualize the initial surface morphology and the morphological changes on the specimens' surface after repolishing. A highly significant difference was found between Ra 1EMP and Ra 2EMP (p < 0.001), between Ra 1GR and Ra 2GR (p < 0.001), as well as between Ra 2EMP and Ra 2GR (p < 0.001), when compared in pairs. A highly significant difference (p < 0.001) was also found between ΔRa EMP and ΔRa GR , with ΔRa GR being higher than ΔRa EMP . The Ra GR values were higher than the Ra EMP values at all times. SEM revealed that both EMP and GR repolished surfaces presented with irregularities; however, in GR specimens major voids and craters were present. EMP was found to perform better when polished by intraoral means compared with GR. Both materials exhibited Ra 2 above the critical threshold for increased plaque accumulation and periodontal inflammation. If enamel-to-enamel roughness found in occlusal contact areas is considered as baseline, both materials were clinically acceptable after repolishing. © 2015 by the American College of Prosthodontists.

Effect of Extreme Wettability on Platelet Adhesion on Metallic Implants: From Superhydrophilicity to Superhydrophobicity.

PubMed

Moradi, Sona; Hadjesfandiari, Narges; Toosi, Salma Fallah; Kizhakkedathu, Jayachandran N; Hatzikiriakos, Savvas G

2016-07-13

In order to design antithrombotic implants, the effect of extreme wettability (superhydrophilicity to superhydrophobicity) on the biocompatibility of the metallic substrates (stainless steel and titanium) was investigated. The wettability of the surface was altered by chemical treatments and laser ablation methods. The chemical treatments generated different functionality groups and chemical composition as evident from XPS analysis. The micro/nanopatterning by laser ablation resulted in three different pattern geometry and different surface roughness and consequently wettability. The patterned surface were further modified with chemical treatments to generate a wide range of surface wettability. The influence of chemical functional groups, pattern geometry, and surface wettability on protein adsorption and platelet adhesion was studied. On chemically treated flat surfaces, the type of hydrophilic treatment was shown to be a contributing factor that determines the platelet adhesion, since the hydrophilic oxidized substrates exhibit less platelet adhesion in comparison to the control untreated or acid treated surfaces. Also, the surface morphology, surface roughness, and superhydrophobic character of the surfaces are contributing factors to platelet adhesion on the surface. Our results show that superhydrophobic cauliflower-like patterns are highly resistant to platelet adhesion possibly due to the stability of Cassie-Baxter state for this pattern compared to others. Our results also show that simple surface treatments on metals offer a novel way to improve the hemocompatibility of metallic substrates.

Graphene-based textured surface by pulsed laser deposition as a robust platform for surface enhanced Raman scattering applications

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

Tite, T.; Donnet, C.; Loir, A.-S.

We have developed a surface enhanced Raman scattering (SERS)-active substrate based on gold nanoparticles-decorated few-layer (fl) graphene grown by pulsed laser deposition. Diamond-Like Carbon film has been converted to fl-graphene after thermal annealing at low temperature. The formation of fl-graphene was confirmed by Raman spectroscopy, and surface morphology was highlighted by scanning electron microscopy. We found that textured fl-graphene film with nanoscale roughness was highly beneficial for SERS detection. Rhodamine 6G and p-aminothiophenol proposed as test molecules were detected with high sensitivity. The detection at low concentration of deltamethrin, an active molecule of a commercial pesticide was further demonstrated.

Extraction of quantitative surface characteristics from AIRSAR data for Death Valley, California

NASA Technical Reports Server (NTRS)

Kierein-Young, K. S.; Kruse, F. A.

1992-01-01

Polarimetric Airborne Synthetic Aperture Radar (AIRSAR) data were collected for the Geologic Remote Sensing Field Experiment (GRSFE) over Death Valley, California, USA, in Sep. 1989. AIRSAR is a four-look, quad-polarization, three frequency instrument. It collects measurements at C-band (5.66 cm), L-band (23.98 cm), and P-band (68.13 cm), and has a GIFOV of 10 meters and a swath width of 12 kilometers. Because the radar measures at three wavelengths, different scales of surface roughness are measured. Also, dielectric constants can be calculated from the data. The AIRSAR data were calibrated using in-scene trihedral corner reflectors to remove cross-talk; and to calibrate the phase, amplitude, and co-channel gain imbalance. The calibration allows for the extraction of accurate values of rms surface roughness, dielectric constants, sigma(sub 0) backscatter, and polarization information. The radar data sets allow quantitative characterization of small scale surface structure of geologic units, providing information about the physical and chemical processes that control the surface morphology. Combining the quantitative information extracted from the radar data with other remotely sensed data sets allows discrimination, identification and mapping of geologic units that may be difficult to discern using conventional techniques.

Nanofinishing of BK7 glass using a magnetorheological solid rotating core tool.

PubMed

Kumar, Sumit; Singh, Anant Kumar

2018-02-01

Surface finishing is a promising method to improve the optical characteristics of crown glass. BK7 finds its applications in transmissive optics, i.e., lenses of binoculars, lenses of microscopes, lenses of telescopes, and light-emitting diodes. The magnetorheological (MR) nanofinishing of optical glasses using a solid rotating core tool is found more advantageous than the other advanced finishing processes in aspects such as precision and accuracy. In the present research, the MR nanofinishing with a solid rotating core tool is carried out on the BK7 glass of size 10×10×3  mm. Response surface methodology is conducted in order to find the optimum process parameters. The effects of process parameters on the percentage change in surface roughness are analyzed. The best surface roughness R a and R q values are achieved at 22 nm and 32 nm from the initial of 41 nm and 57 nm in 30 min of the finishing time cycle. To study the surface morphology of nanofinished BK7 glass, scanning electron microscopy is performed with sputter coating of gold on a glass specimen.

Electrode erosion properties of gas spark switches for fast linear transformer drivers

NASA Astrophysics Data System (ADS)

Li, Xiaoang; Pei, Zhehao; Zhang, Yuzhao; Liu, Xuandong; Li, Yongdong; Zhang, Qiaogen

2017-12-01

Fast linear transformer drivers (FLTDs) are a popular and potential route for high-power devices employing multiple "bricks" in series and parallel, but they put extremely stringent demands on gas switches. Electrode erosion of FLTD gas switches is a restrictive and unavoidable factor that degrades performance and limits stability. In this paper, we systematically investigated the electrode erosion characteristics of a three-electrode field distortion gas switch under the typical working conditions of FLTD switches, and the discharge current was 7-46 kA with 46-300 ns rise time. A high speed frame camera and a spectrograph were used to capture the expansion process and the spectral emission of the spark channel was used to estimate the current density and the spark temperature, and then the energy fluxes and the external forces on the electrode surface were calculated. A tens of kilo-ampere nanosecond pulse could generate a 1011 W/m2 energy flux injection and 1.3-3.5 MPa external pressure on the electrode surface, resulting in a millimeter-sized erosion crater with the maximum peak height Rz reaching 100 μm magnitude. According to the morphological images by a laser scanning confocal microscope, the erosion crater of a FLTD switch contained three kinds of local morphologies, namely a center boiling region, an overflow region and a sputtering region. In addition, the crater size, the surface roughness, and the mass loss were highly dependent on the current amplitude and the transferred charge. We also observed Morphology Type I and Type II, respectively, with different pulse parameters, which had an obvious influence on surface roughness and mass loss. Finally, the quantitative relationship between the electrode mass loss and the pulse parameter was clarified. The transferred charge and the current amplitude were proved to be the main factors determining the electrode mass loss of a FLTD switch, and a least squares fitting expression for mass loss was also obtained.

Effect of the seed layer on the Y0.5Gd0.5Ba2Cu3O7-σ film fabricated by PLD

NASA Astrophysics Data System (ADS)

Yao, Yanjie; Wang, Wei; Liu, Linfei; Lu, Saidan; Wu, Xiang; Zheng, Tong; Liu, Shunfan; Li, Yijie

2018-06-01

The surface morphology and internal residual stress have influence on the critical current density (Jc) of REBa2Cu3O7-σ (REBCO) coated conductor. In order to modulate them, a series of Y0.5Gd0.5Ba2Cu3O7-σ (YGBCO) films were prepared by pulsed laser deposition (PLD) through introducing a seed layer in this paper. The thicknesses of seed layer changes from about 2 nm to 30 nm. For comparison, a standard sample without seed layer was fabricated at the same deposition condition. The surface morphology was illustrated by Scanning electron microscopy (SEM). The surface roughness was scanned by Atomic force microscopy (AFM). The microstructure and internal strain were measured by X-ray Diffraction (XRD). DC four-probe method was used to measure the critical current of the samples at 77 K and self-field. As a result, all samples have high Jc of about 4 MA/cm2, while the self-field Jc of the YGBCO films can be promoted by the seed layer. The results of our research work are as follows. First of all, seed layer makes the deposition of the YGBCO layer much easier to control. By this way, we can decrease the surface roughness of the samples. Furthermore, the internal residual stress of the YGBCO films with seed layer decrease. Finally, the best thickness of the seed layer was found by summarizing and analyzing the conditions of seed layer.

Effect of hyaluronic acid on morphological changes to dentin surfaces and subsequent effect on periodontal ligament cell survival, attachment, and spreading.

PubMed

Mueller, Andrea; Fujioka-Kobayashi, Masako; Mueller, Heinz-Dieter; Lussi, Adrian; Sculean, Anton; Schmidlin, Patrick R; Miron, Richard J

2017-05-01

Hyaluronic acid (HA) is a natural constituent of connective tissues and plays an important role in their development, maintenance, and regeneration. Recently, HA has been shown to improve wound healing. However, no basic in vitro study to date has investigated its mode of action. Therefore, the purpose of this study was to examine morphological changes of dentin surfaces following HA coating and thereafter investigate the influence of periodontal ligament (PDL) cell survival, attachment, and spreading to dentin discs. HA was coated onto dentin discs utilizing either non-cross-linked (HA) or cross-linked (HA cl) delivery systems. Morphological changes to dentin discs were then assessed using scanning electron microscopy (SEM). Thereafter, human PDL cells were seeded under three in vitro conditions including (1) dilution of HA (1:100), (2) dilution of HA (1:10), and (3) HA coated directly to dentin discs. Samples were then investigated for PDL cell survival, attachment, and spreading using a live/dead assay, cell adhesion assay, and SEM imaging, respectively. While control dentin discs demonstrated smooth surfaces both at low and high magnification, the coating of HA altered surface texture of dentin discs by increasing surface roughness. HA cl further revealed greater surface texture/roughness likely due to the cross-linking carrier system. Thereafter, PDL cells were seeded on control and HA coated dentin discs and demonstrated a near 100 % survival rate for all samples demonstrating high biocompatibility of HA at dilutions of both 1:100 and 1:10. Interestingly, non-cross-linked HA significantly increased cell numbers at 8 h, whereas cross-linked HA improved cell spreading as qualitatively assessed by SEM. The results from the present study demonstrate that both carrier systems for HA were extremely biocompatible and demonstrated either improved cell numbers or cell spreading onto dentin discs. Future in vitro and animal research is necessary to further characterize the optimal delivery system of HA for improved clinical use. HA is a highly biocompatible material that may improve PDL cell attachment or spreading on dentin.

Three-dimensional kinetic Monte Carlo simulations of cubic transition metal nitride thin film growth

NASA Astrophysics Data System (ADS)

Nita, F.; Mastail, C.; Abadias, G.

2016-02-01

A three-dimensional kinetic Monte Carlo (KMC) model has been developed and used to simulate the microstructure and growth morphology of cubic transition metal nitride (TMN) thin films deposited by reactive magnetron sputtering. Results are presented for the case of stoichiometric TiN, chosen as a representative TMN prototype. The model is based on a NaCl-type rigid lattice and includes deposition and diffusion events for both N and Ti species. It is capable of reproducing voids and overhangs, as well as surface faceting. Simulations were carried out assuming a uniform flux of incoming particles approaching the surface at normal incidence. The ballistic deposition model is parametrized with an interaction parameter r0 that mimics the capture distance at which incoming particles may stick on the surface, equivalently to a surface trapping mechanism. Two diffusion models are implemented, based on the different ways to compute the site-dependent activation energy for hopping atoms. The influence of temperature (300-500 K), deposition flux (0.1-100 monolayers/s), and interaction parameter r0 (1.5-6.0 Å) on the obtained growth morphology are presented. Microstructures ranging from highly porous, [001]-oriented straight columns with smooth top surface to rough columns emerging with different crystallographic facets are reproduced, depending on kinetic restrictions, deposited energy (seemingly captured by r0), and shadowing effect. The development of facets is a direct consequence of the diffusion model which includes an intrinsic (minimum energy-based) diffusion anisotropy, although no crystallographic diffusion anisotropy was explicitly taken into account at this stage. The time-dependent morphological evolution is analyzed quantitatively to extract the growth exponent β and roughness exponent α , as indicators of kinetic roughening behavior. For dense TiN films, values of α ≈0.7 and β =0.24 are obtained in good agreement with existing experimental data. At this stage a single lattice is considered but the KMC model will be extended further to address more complex mechanisms, such as anisotropic surface diffusion and grain boundary migration at the origin of the competitive columnar growth observed in polycrystalline TiN-based films.

Surface morphology study in high speed milling of soda lime glass

NASA Astrophysics Data System (ADS)

Konneh, Mohamed; Bagum, Mst. Nasima; Ali, Mohammad Yeakub; Amin, A. K. M. Nurul

2018-05-01

Soda lime glass has a wide range of applications in optical, bio-medical and semi-conductor industries. It is undeniably a challenging task to produce micro finish surface on an amorphous brittle solid like soda lime glass due to its low fracture toughness. In order to obtain such a finish surface, ductile machining has been exploited, as this usually cause's plastic flow which control crack propagation. At sub-micro scale cutting parameters, researchers achieved nano finish surface in micro milling operation using coated tool. However it is possible to enhance the rate of material removal (RMR) of soda lime glass at flexible cutting condition. High speed cutting at micro meter level, extend of thermal softening might be prominent than the strain gradient strengthening. The purpose of this study was to explore the effects of high cutting speed end milling parameters on the surface texture of soda lime glass using uncoated carbide tool. The spindle speed, depth of cut and feed rate were varied from 20,000 to 40,000 rpm, 10 to 30 mm/min and 30 to 50 µm respectively. Mathematical model of roughness has been developed using Response Surface Methodology (RSM). Experimental verification confirmed that surface roughness (Ra) 0.38 µm is possible to achieve at increased RMR, 4.71 mm3/min.

Mechanism analysis on finishing of reaction-sintered silicon carbide by combination of water vapor plasma oxidation and ceria slurry polishing

NASA Astrophysics Data System (ADS)

Shen, Xinmin; Tu, Qunzhang; Deng, Hui; Jiang, Guoliang; Yamamura, Kazuya

2015-05-01

Reaction-sintered silicon carbide (RS-SiC), which is considered as a promising mirror material for space telescope systems, requires a high surface property. An ultrasmooth surface with a Ra surface roughness of 0.480 nm was obtained after water vapor plasma oxidation for 90 min followed by ceria slurry polishing for 40 min. The oxidation process of RS-SiC by water vapor plasma was analyzed based on the Deal-Grove model, and the theoretical calculation results are consistent with the measured data obtained by scanning white light interferometer (SWLI), scanning electron microscopy/energy-dispersive x-ray, and atomic force microscope. The polishing process of oxidized RS-SiC by ceria slurry was investigated according to the Preston equation, which would theoretically forecast the evolutions of RS-SiC surfaces along with the increasing of polishing time, and it was experimentally verified by comparing the surface roughnesses obtained by SWLI and the surface morphologies obtained by SEM. The mechanism analysis on the finishing of RS-SiC would be effective for the optimization of water vapor plasma oxidation parameters and ceria slurry polishing parameters, which will promote the application of RS-SiC substrates by improving the surface property obtained by the oxidation-assisted polishing method.

Effect of surface roughness on droplet splashing

NASA Astrophysics Data System (ADS)

Hao, Jiguang

2017-12-01

It is well known that rough surfaces trigger prompt splashing and suppress corona splashing on droplet impact. Upon water droplet impact, we experimentally found that a slightly rough substrate triggers corona splashing which is suppressed to prompt splashing by both further increase and further decrease of surface roughness. The nonmonotonic effect of surface roughness on corona splashing weakens with decreasing droplet surface tension. The threshold velocities for prompt splashing and corona splashing are quantified under different conditions including surface roughness, droplet diameter, and droplet surface tension. It is determined that slight roughness significantly enhances both prompt splashing and corona splashing of a water droplet, whereas it weakly affects low-surface-tension droplet splashing. Consistent with previous studies, high roughness triggers prompt splashing and suppresses corona splashing. Further experiments on droplet spreading propose that the mechanism of slight roughness enhancing water droplet splashing is due to the decrease of the wetted area with increasing surface roughness.

Thermal shock behavior of W-ZrC/Sc2O3 composites under two different transient events by electron and laser irradiation

NASA Astrophysics Data System (ADS)

Chen, Hong-Yu; Luo, Lai-Ma; Zan, Xiang; Xu, Qiu; Tokunaga, Kazutoshi; Liu, Jia-Qin; Zhu, Xiao-Yong; Cheng, Ji-Gui; Wu, Yu-Cheng

2018-02-01

The transient thermal shock behaviors of W-ZrC/Sc2O3 composites with different ZrC contents were evaluated using transient thermal shock test by electron and laser beams. The effects of different ZrC doping contents on the surface morphology and thermal shock resistance of W-ZrC/Sc2O3 composites were then investigated. Similarity and difference between effects of electron and laser beam transient heat loading were also discussed in this study. Repeated heat loading resulted in thermal fatigue of the irradiated W-ZrC/Sc2O3 samples by thermal stress, leading to the rough surface morphologies with cracks. After different transient thermal tests, significant surface roughening, cracks, surface melting, and droplet ejection occurred. W-2vol.%Sc2O3 sample has superior thermal properties and greater resistance to surface modifications under transient thermal shock, and with the increasing ZrC content in W alloys, thermal shock resistance of W-Zr/Sc2O3 sample tends to be unsatisfied.

Ultrathin Au film on polymer surface for surface plasmon polariton waveguide application

NASA Astrophysics Data System (ADS)

Liu, Tong; Ji, Lanting; He, Guobing; Sun, Xiaoqiang; Wang, Fei; Zhang, Daming

2017-11-01

Formation of laterally continuous ultrathin gold films on polymer substrates is a technological challenge. In this work, the vacuum thermal evaporation method is adopted to form continuous Au films in the thickness range of 7-17 nm on polymers of Poly(methyl-methacrylate-glycidly-methacrylate) and SU-8 film surface without using the adhesion or metallic seeding layers. Absorption spectrum, scanning electron microscope and atomic force microscope images are used to characterize the Au film thickness, roughness and optical loss. The result shows that molecular-scale structure, surface energy and electronegativity have impacts on the Au film morphology on polymers. Wet chemical etching is used to fabricate 7-nm thick Au stripes embedded in polymer claddings. These long-range surface plasmon polariton waveguides demonstrate the favorable morphological configurations and cross-sectional states. Through the end-fire excitation method, propagation losses of 6-μm wide Au stripes are compared to theoretical values and analyzed from practical film status. The smooth, patternable gold films on polymer provide potential applications to plasmonic waveguides, biosensing, metamaterials and optical antennas.

Shrink-induced graphene sensor for alpha-fetoprotein detection with low-cost self-assembly and label-free assay

NASA Astrophysics Data System (ADS)

Sando, Shota; Zhang, Bo; Cui, Tianhong

2017-12-01

Combination of shrink induced nano-composites technique and layer-by-layer (LbL) self-assembled graphene challenges controlling surface morphology. Adjusting shrink temperature achieves tunability on graphene surface morphology on shape memory polymers, and it promises to be an alternative in fields of high-surface-area conductors and molecular detection. In this study, self-assembled graphene on a shrink polymer substrate exhibits nanowrinkles after heating. Induced nanowrinkles on graphene with different shrink temperature shows distinct surface roughness and wettability. As a result, it becomes more hydrophilic with higher shrink temperatures. The tunable wettability promises to be utilized in, for example, microfluidic devices. The graphene on shrink polymer also exhibits capability of being used in sensing applications for pH and alpha-fetoprotein (AFP) detection with advantages of label free and low cost, due to self-assembly technique, easy functionalization, and antigen-antibody reaction on graphene surface. The detection limit of AFP detection is down to 1 pg/mL, and therefore the sensor also has a significant potential for biosensing as it relies on low-cost self-assembly and label-free assay.

A model system to mimic environmentally active surface film roughness and hydrophobicity.

PubMed

Grant, Jacob S; Shaw, Scott K

2017-10-01

This work presents the development and initial assessment of a laboratory platform to allow quantitative studies on model urban films. The platform consists of stearic acid and eicosane mixtures that are solution deposited from hexanes onto smooth, solid substrates. We show that this model has distinctive capabilities to better mimic a naturally occurring film's morphology and hydrophobicity, two important parameters that have not previously been incorporated into model film systems. The physical and chemical properties of the model films are assessed using a variety of analytical instruments. The film thickness and roughness are probed via atomic force microscopy while the film composition, wettability, and water uptake are analyzed by Fourier transform infrared spectroscopy, contact angle goniometry, and quartz crystal microbalance, respectively. Simulated environmental maturation is achieved by exposing the film to regulated amounts of UV/ozone. Ultimately, oxidation of the film is monitored by the analytical techniques mentioned above and proceeds as expected to produce a utile model film system. Including variable roughness and tunable surface coverage results in several key advantages over prior model systems, and will more accurately represent native urban film behavior. Copyright © 2017 Elsevier Ltd. All rights reserved.

Strain relaxation of thick (11–22) semipolar InGaN layer for long wavelength nitride-based device

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

Kim, Jaehwan; Min, Daehong; Jang, Jongjin

2014-10-28

In this study, the properties of thick stress-relaxed (11–22) semipolar InGaN layers were investigated. Owing to the inclination of growth orientation, misfit dislocations (MDs) occurred at the heterointerface when the strain state of the (11–22) semipolar InGaN layers reached the critical point. We found that unlike InGaN layers based on polar and nonpolar growth orientations, the surface morphologies of the stress-relaxed (11–22) semipolar InGaN layers did not differ from each other and were similar to the morphology of the underlying GaN layer. In addition, misfit strain across the whole InGaN layer was gradually relaxed by MD formation at the heterointerface.more » To minimize the effect of surface roughness and defects in GaN layers on the InGaN layer, we conducted further investigation on a thick (11–22) semipolar InGaN layer grown on an epitaxial lateral overgrown GaN template. We found that the lateral indium composition across the whole stress-relaxed InGaN layer was almost uniform. Therefore, thick stress-relaxed (11–22) semipolar InGaN layers are suitable candidates for use as underlying layers in long-wavelength devices, as they can be used to control strain accumulation in the heterostructure active region without additional influence of surface roughness.« less

Synthesis and Characterization of Hydrophobic Silica Thin Layer Derived from Methyltrimethoxysilane (MTMS)

NASA Astrophysics Data System (ADS)

Darmawan, Adi; Utari, Riyadini; Eka Saputra, Riza; Suhartana; Astuti, Yayuk

2018-01-01

This study investigated the synthesis and characterization of MTMS hydrophobic silica prepared by sol-gel method. In principle, silica xerogels and silica thin layer were obtained by reacting MTMS in ethanol solvent in some pH variations. The MTMS solution was used to modify the surface of the ceramic plate by dipcoating method to further be calcined at two different temperatures of 350°C and 500°C. The silica xerogels were analysed by FTIR, TGA-DSC and GSA to determine functional group characteristics, thermal properties and pore morphology respectively. Meanwhile, the silica thin layers were analysed their hydrophobic properties using water contact angle measurement and surface roughness determination using SEM. The results showed that the higher the pH used in the MTMS solution, the higher the resulting contact angle. The highest contact angle was obtained at pH 8.12 which reached 94.7° and 79.5° for silica thin layer calcined at 350°C and 500°C, respectively. The TGA results indicated that the methyl group survived up to 400°C and disappeared at 500°C which had implications on silica thin layer hydrophobic nature. GSA result exhibited that the silica xerogel had a close structure with a very low pore volume. While the SEM-EDX results displayed that the silica thin layer prepared at acidic pH had smoother surface morphology and became rough when prepared at an alkaline pH.

Linking playa surface dust emission potential to feedbacks between surface moisture and salt crust expansion through high resolution terrestrial laser scanning measurements

NASA Astrophysics Data System (ADS)

Nield, J. M.; King, J.; Wiggs, G.

2012-12-01

The dust emissivity of salt pans (or playas) can be significant but is controlled by interactions between wind erosivity, surface moisture, salt chemistry and crust morphology. These surface properties influence the aeolian transport threshold and can be highly variable over both short temporal and spatial scales. In the past, field studies have been hampered by practical difficulties in accurately measuring properties controlling sediment availability at the surface in high resolution. Studies typically therefore, have investigated large scale monthly or seasonal change using remote sensing and assume a homogeneous surface when predicting dust emissivity. Here we present the first high resolution measurements (sub-cm) of salt crust expansion related to changes in diurnal moisture over daily and weekly time periods using terrestrial laser scanning (TLS, ground-based LiDAR) on Sua Pan, Botswana. The TLS measures both elevation and relative surface moisture change simultaneously, without disturbing the surface. Measurement sequences enable the variability in aeolian sediment availability to be quantified along with temporal feedbacks associated with crust degradation. On crusts with well-developed polygon ridges (high aerodynamic and surface roughness), daily surface expansion was greater than 30mm. The greatest surface change occurred overnight on the upper, exposed sections of the ridges, particularly when surface temperatures dropping below 10°C. These areas also experienced the greatest moisture variation and became increasingly moist overnight in response to an increase in relative humidity. In contrast, during daylight hours, the ridge areas were drier than the lower lying inter-ridge areas. Positive feedbacks between surface topography and moisture reinforced the maximum diurnal moisture variation at ridge peaks, encouraging crust thrusting due to overnight salt hydration, further enhancing the surface, and therefore, aerodynamic roughness. These feedbacks between surface roughness and moisture have implications for dust emissivity because crust expansion increases fluff production which is one of the main dust source materials. Further, increased roughness can locally increase wind erosivity and the potential evaporation of ridge areas. Crust thrusting also weakens the ridge peaks, developing cracked surfaces and exposing the sediment supply source below. These fast acting processes can have a major influence on wind erosion variability and dust emissivity from key dust source regions.; a-d) Elevation change overnight. e-f) Elevation change over 6 days.

Lacunarity study of speckle patterns produced by rough surfaces

NASA Astrophysics Data System (ADS)

Dias, M. R. B.; Dornelas, D.; Balthazar, W. F.; Huguenin, J. A. O.; da Silva, L.

2017-11-01

In this work we report on the study of Lacunarity of digital speckle patterns generated by rough surfaces. The study of Lacunarity of speckle patterns was performed on both static and moving rough surfaces. The results show that the Lacunarity is sensitive to the surface roughness, which suggests that it can be used to perform indirect measurement of surface roughness as well as to monitor defects, or variations of roughness, of metallic moving surfaces. Our results show the robustness of this statistical tool applied to speckle pattern in order to study surface roughness.

Biocompatibility assessment of spark plasma-sintered alumina-titanium cermets.

PubMed

Guzman, Rodrigo; Fernandez-García, Elisa; Gutierrez-Gonzalez, Carlos F; Fernandez, Adolfo; Lopez-Lacomba, Jose Luis; Lopez-Esteban, Sonia

2016-01-01

Alumina-titanium materials (cermets) of enhanced mechanical properties have been lately developed. In this work, physical properties such as electrical conductivity and the crystalline phases in the bulk material are evaluated. As these new cermets manufactured by spark plasma sintering may have potential application for hard tissue replacements, their biocompatibility needs to be evaluated. Thus, this research aims to study the cytocompatibility of a novel alumina-titanium (25 vol. % Ti) cermet compared to its pure counterpart, the spark plasma sintered alumina. The influence of the particular surface properties (chemical composition, roughness and wettability) on the pre-osteoblastic cell response is also analyzed. The material electrical resistance revealed that this cermet may be machined to any shape by electroerosion. The investigated specimens had a slightly undulated topography, with a roughness pattern that had similar morphology in all orientations (isotropic roughness) and a sub-micrometric average roughness. Differences in skewness that implied valley-like structures in the cermet and predominance of peaks in alumina were found. The cermet presented a higher surface hydrophilicity than alumina. Any cytotoxicity risk associated with the new materials or with the innovative manufacturing methodology was rejected. Proliferation and early-differentiation stages of osteoblasts were statistically improved on the composite. Thus, our results suggest that this new multifunctional cermet could improve current alumina-based biomedical devices for applications such as hip joint replacements. © The Author(s) 2015.

The role of the substrate surface morphology and water in growth of vertically aligned single-walled carbon nanotubes.

PubMed

Pint, Cary; Pheasant, Sean; Nicholas, Nolan; Horton, Charles; Hauge, Robert

2008-11-01

Growth of high quality, vertically aligned single-walled carbon nanotubes (carpets) is achieved using a rapid insertion hot filament chemical vapor deposition (HF-CVD) technique. The effect of the substrate morphology on growth is explored by comparing carpets grown on epitaxially polished MgO substrates to those grown on "as-cut", macroscopically rough MgO substrates. Depending on the substrate morphology, we observe differences in both the overall carpet morphology as well as the diameter distribution of nanotubes grown in the carpet based on optical measurements. In addition, we explore the role of water in the growth of carpets on MgO and the conventional Al2O3 coated Si substrates. We find that the addition of a small amount of water is beneficial to the growth rates of the SWNT carpets, enhancing the growth rates by up to eight times.

Surface correlations of hydrodynamic drag for transitionally rough engineering surfaces

NASA Astrophysics Data System (ADS)

Thakkar, Manan; Busse, Angela; Sandham, Neil

2017-02-01

Rough surfaces are usually characterised by a single equivalent sand-grain roughness height scale that typically needs to be determined from laboratory experiments. Recently, this method has been complemented by a direct numerical simulation approach, whereby representative surfaces can be scanned and the roughness effects computed over a range of Reynolds number. This development raises the prospect over the coming years of having enough data for different types of rough surfaces to be able to relate surface characteristics to roughness effects, such as the roughness function that quantifies the downward displacement of the logarithmic law of the wall. In the present contribution, we use simulation data for 17 irregular surfaces at the same friction Reynolds number, for which they are in the transitionally rough regime. All surfaces are scaled to the same physical roughness height. Mean streamwise velocity profiles show a wide range of roughness function values, while the velocity defect profiles show a good collapse. Profile peaks of the turbulent kinetic energy also vary depending on the surface. We then consider which surface properties are important and how new properties can be incorporated into an empirical model, the accuracy of which can then be tested. Optimised models with several roughness parameters are systematically developed for the roughness function and profile peak turbulent kinetic energy. In determining the roughness function, besides the known parameters of solidity (or frontal area ratio) and skewness, it is shown that the streamwise correlation length and the root-mean-square roughness height are also significant. The peak turbulent kinetic energy is determined by the skewness and root-mean-square roughness height, along with the mean forward-facing surface angle and spanwise effective slope. The results suggest feasibility of relating rough-wall flow properties (throughout the range from hydrodynamically smooth to fully rough) to surface parameters.

Characteristics of Saccharomyces cerevisiae yeasts exhibiting rough colonies and pseudohyphal morphology with respect to alcoholic fermentation.

PubMed

Reis, Vanda Renata; Bassi, Ana Paula Guarnieri; da Silva, Jessica Carolina Gomes; Ceccato-Antonini, Sandra Regina

2013-12-01

Among the native yeasts found in alcoholic fermentation, rough colonies associated with pseudohyphal morphology belonging to the species Saccharomyces cerevisiae are very common and undesirable during the process. The aim of this work was to perform morphological and physiological characterisations of S. cerevisiae strains that exhibited rough and smooth colonies in an attempt to identify alternatives that could contribute to the management of rough colony yeasts in alcoholic fermentation. Characterisation tests for invasiveness in Agar medium, killer activity, flocculation and fermentative capacity were performed on 22 strains (11 rough and 11 smooth colonies). The effects of acid treatment at different pH values on the growth of two strains ("52"--rough and "PE-02"--smooth) as well as batch fermentation tests with cell recycling and acid treatment of the cells were also evaluated. Invasiveness in YPD Agar medium occurred at low frequency; ten of eleven rough yeasts exhibited flocculation; none of the strains showed killer activity; and the rough strains presented lower and slower fermentative capacities compared to the smooth strains in a 48-h cycle in a batch system with sugar cane juice. The growth of the rough strain was severely affected by the acid treatment at pH values of 1.0 and 1.5; however, the growth of the smooth strain was not affected. The fermentative efficiency in mixed fermentation (smooth and rough strains in the same cell mass proportion) did not differ from the efficiency obtained with the smooth strain alone, most likely because the acid treatment was conducted at pH 1.5 in a batch cell-recycle test. A fermentative efficiency as low as 60% was observed with the rough colony alone.

Characteristics of Saccharomyces cerevisiae yeasts exhibiting rough colonies and pseudohyphal morphology with respect to alcoholic fermentation

PubMed Central

Reis, Vanda Renata; Bassi, Ana Paula Guarnieri; da Silva, Jessica Carolina Gomes; Ceccato-Antonini, Sandra Regina

2013-01-01

Among the native yeasts found in alcoholic fermentation, rough colonies associated with pseudohyphal morphology belonging to the species Saccharomyces cerevisiae are very common and undesirable during the process. The aim of this work was to perform morphological and physiological characterisations of S. cerevisiae strains that exhibited rough and smooth colonies in an attempt to identify alternatives that could contribute to the management of rough colony yeasts in alcoholic fermentation. Characterisation tests for invasiveness in Agar medium, killer activity, flocculation and fermentative capacity were performed on 22 strains (11 rough and 11 smooth colonies). The effects of acid treatment at different pH values on the growth of two strains (“52” - rough and “PE-02” - smooth) as well as batch fermentation tests with cell recycling and acid treatment of the cells were also evaluated. Invasiveness in YPD Agar medium occurred at low frequency; ten of eleven rough yeasts exhibited flocculation; none of the strains showed killer activity; and the rough strains presented lower and slower fermentative capacities compared to the smooth strains in a 48-h cycle in a batch system with sugar cane juice. The growth of the rough strain was severely affected by the acid treatment at pH values of 1.0 and 1.5; however, the growth of the smooth strain was not affected. The fermentative efficiency in mixed fermentation (smooth and rough strains in the same cell mass proportion) did not differ from the efficiency obtained with the smooth strain alone, most likely because the acid treatment was conducted at pH 1.5 in a batch cell-recycle test. A fermentative efficiency as low as 60% was observed with the rough colony alone. PMID:24688501

Bandgap Tuning of GaAs/GaAsSb Core-Shell Nanowires Grown by Molecular Beam Epitaxy

DTIC Science & Technology

2015-09-21

SECURITY CLASSIFICATION OF: Semiconductor nanowires have been identified as a viable technology for next-generation infrared (IR) photodetectors with... nanowires , by varying the Sb content using Ga-assisted molecular beam epitaxy. An increase in Sb content leads to strain accumulation in shell...manifesting in rough surface morphology, multifaceted growths, curved nanowires , and deterioration in the 1. REPORT DATE (DD-MM-YYYY) 4. TITLE AND SUBTITLE

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.

Radar, visual and thermal characteristics of Mars: Rough planar surfaces

USGS Publications Warehouse

Schaber, G.G.

1980-01-01

High-resolution Viking Orbiter images (10 to 15 m/pixel) contain significant information on Martian surface roughness at 25- to 100-m lateral scales, whereas Earth-based radar observations of Mars are sensitive to roughness at lateral scales of 1 to 30 m, or more. High-rms slopes predicted for the Tharsis-Memnonia-Amazonis volcanic plains from extremely weak radar returns (low peak radar cross section) are qualitatively confirmed by the Viking image data. Large-scale, curvilinear (but parallel) ridges on lava flows in the Memnonia Fossae region are interpreted as innate flow morphology caused by compressional foldover of moving lava sheets of possible rhyolite-dacite composition. The presence or absence of a recent mantle of fine-grained eolian material on the volcanic surfaces studied was determined by the visibility of fresh impact craters with diameters less than 50 m. Lava flows south and west of Arsia Mons, and within the large region of low thermal inertia centered on Tharsis Montes (H. H. Kieffer et al., 1977, J. Geophys. Res.82, 4249-4291), were found to possess such a recent mantle. At predawn residual temperatures ??? -10K (south boundary of this low-temperature region), lava flows are shown to have relatively old eolian mantles. Lava flows with surfaces modified by eolian erosion and deposition occur west-northwest of Apollinaris Patera at the border of the cratered equatorial uplands and southern Elysium Planitia. Nearby yardangs, for which radar observations indicate very high-rms slopes, are similar to terrestrial features of similar origin. ?? 1980.

Surface studies on superhydrophobic and oleophobic polydimethylsiloxane-silica nanocomposite coating system

NASA Astrophysics Data System (ADS)

Basu, Bharathibai J.; Dinesh Kumar, V.; Anandan, C.

2012-11-01

Superhydrophobic and oleophobic polydimethylsiloxane (PDMS)-silica nanocomposite double layer coating was fabricated by applying a thin layer of low surface energy fluoroalkyl silane (FAS) as topcoat. The coatings exhibited WCA of 158-160° and stable oleophobic property with oil CA of 79°. The surface morphology was characterized by field emission scanning electron microscopy (FESEM) and surface chemical composition was determined by energy dispersive X-ray spectrometery (EDX) and X-ray photoelectron spectroscopy (XPS). FESEM images of the coatings showed micro-nano binary structure. The improved oleophobicity was attributed to the combined effect of low surface energy of FAS and roughness created by the random distribution of silica aggregates. This is a facile, cost-effective method to obtain superhydrophobic and oleophobic surfaces on larger area of various substrates.

Plasma surface modification of polypropylene track-etched membrane to improve its performance properties

NASA Astrophysics Data System (ADS)

Kravets, L. I.; Elinson, V. M.; Ibragimov, R. G.; Mitu, B.; Dinescu, G.

2018-02-01

The surface and electrochemical properties of polypropylene track-etched membrane treated by plasma of nitrogen, air and oxygen are studied. The effect of the plasma-forming gas composition on the surface morphology is considered. It has been found that the micro-relief of the membrane surface formed under the gas-discharge etching, changes. Moreover, the effect of the non-polymerizing gas plasma leads to formation of oxygen-containing functional groups, mostly carbonyl and carboxyl. It is shown that due to the formation of polar groups on the surface and its higher roughness, the wettability of the plasma-modified membranes improves. In addition, the presence of polar groups on the membrane surface layer modifies its electrochemical properties so that conductivity of plasma-treated membranes increase.

Surface roughness: A review of its measurement at micro-/nano-scale

NASA Astrophysics Data System (ADS)

Gong, Yuxuan; Xu, Jian; Buchanan, Relva C.

2018-01-01

The measurement of surface roughness at micro-/nano-scale is of great importance to metrological, manufacturing, engineering, and scientific applications given the critical roles of roughness in physical and chemical phenomena. The surface roughness of materials can significantly change the way of how they interact with light, phonons, molecules, and so forth, thus surface roughness ultimately determines the functionality and property of materials. In this short review, the techniques of measuring micro-/nano-scale surface roughness are discussed with special focus on the limitations and capabilities of each technique. In addition, the calculations of surface roughness and their theoretical background are discussed to offer readers a better understanding of the importance of post-measurement analysis. Recent progress on fractal analysis of surface roughness is discussed to shed light on the future efforts in surface roughness measurement.

Why the dish makes a difference: quantitative comparison of polystyrene culture surfaces.

PubMed

Zeiger, Adam S; Hinton, Benjamin; Van Vliet, Krystyn J

2013-07-01

There is wide anecdotal recognition that biological cell viability and behavior can vary significantly as a function of the source of commercial tissue culture polystyrene (TCPS) culture vessels to which those cells adhere. However, this marked material dependency is typically resolved by selecting and then consistently using the same manufacturer's product - following protocol - rather than by investigating the material properties that may be responsible for such experimental variation. Here, we quantified several physical properties of TCPS surfaces obtained from a wide range of commercial sources and processing steps, through the use of atomic force microscopy (AFM)-based imaging and analysis, goniometry and protein adsorption quantification. We identify qualitative differences in surface features, as well as quantitative differences in surface roughness and wettability that cannot be attributed solely to differences in surface chemistry. We also find significant differences in cell morphology and proliferation among cells cultured on different TCPS surfaces, and resolve a correlation between nanoscale surface roughness and cell proliferation rate for both cell types considered. Interestingly, AFM images of living adherent cells on these nanotextured surfaces demonstrate direct interactions between cellular protrusions and topographically distinct features. These results illustrate and quantify the significant differences in material surface properties among these ubiquitous materials, allowing us to better understand why the dish can make a difference in biological experiments. Copyright © 2013 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

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

NASA Astrophysics Data System (ADS)

Razi, Sepehr; Mollabashi, Mahmoud; Madanipour, Khosro

2015-12-01

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

Atomic force microscopy analysis of human cornea surface after UV (λ=266 nm) laser irradiation

NASA Astrophysics Data System (ADS)

Spyratou, E.; Makropoulou, M.; Moutsouris, K.; Bacharis, C.; Serafetinides, A. A.

2009-07-01

Efficient cornea reshaping by laser irradiation for correcting refractive errors is still a major issue of interest and study. Although the excimer laser wavelength of 193 nm is generally recognized as successful in ablating corneal tissue for myopia correction, complications in excimer refractive surgery leads to alternative laser sources and methods for efficient cornea treatment. In this work, ablation experiments of human donor cornea flaps were conducted with the 4th harmonic of an Nd:YAG laser, with different laser pulses. AFM analysis was performed for examination of the ablated cornea flap morphology and surface roughness.

Effect of an aggressive medium on discontinuous deformation of aluminum-magnesium alloy AlMg6

NASA Astrophysics Data System (ADS)

Shibkov, A. A.; Denisov, A. A.; Zolotov, A. E.; Kochegarov, S. S.

2017-01-01

It is experimentally shown that the molecular (chemical) process of surface etching of deformed aluminum-magnesium alloy AlMg6 causes the development of a macroscopic plastic strain step with an amplitude of a few percent. Using numerical simulation of the polycrystalline solid etching process, it is shown that the corrosion front morphology varies during etching from Euclid (flat) to fractal (rough). The results obtained show the key role of the surface state on the development of macroscopic mechanical instability of a material exhibiting the Portevin-Le Chatelier effect.

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

Jung, Min-Cherl; Zhang, Dongrong; Nikiforov, Gueorgui O.

Ultrathin (<6 nm) polycrystalline films of 6,13-bis(triisopropylsilylethynyl) pentacene (TIPS-P) are deposited with a two-step spin-coating process. The influence of spin-coating conditions on morphology of the resulting film was examined by atomic force microscopy. Film thickness and RMS surface roughness were in the range of 4.0–6.1 and 0.6–1.1 nm, respectively, except for small holes. Polycrystalline structure was confirmed by grazing incidence x-ray diffraction measurements. Near-edge x-ray absorption fine structure measurements suggested that the plane through aromatic rings of TIPS-P molecules was perpendicular to the substrate surface.

Preparation of Superhydrophobic Film on Ti Substrate and Its Anticorrosion Property

PubMed Central

Zhu, Min; Tang, Wenchuan; Huang, Luyao; Zhang, Dawei; Du, Cuiwei; Yu, Gaohong; Chen, Ming; Chowwanonthapunya, Thee

2017-01-01

Superhydrophobic films were fabricated on a titanium substrate with or without anodizing by using a self-assembling method. Firstly, the pretreatments of mechanical polishing/anodizing or mechanical polishing only were conducted, respectively. Subsequently, the preparation of polydopamine film layer, deposition of nano-silver particles, and post modification of 1H,1H,2H,2H-perfluorodecanethiol were performed on the surface of the pretreated substrate. The surface morphologies, compositions, wettability, and corrosion resistance of the films were investigated with scanning electron microscopy (SEM), energy-dispersive spectrometry (EDS), water contact angle measurements, and electrochemical tests, respectively. Meanwhile, the effect of the deposition time in the silver nitrate solution on the hydrophobicity of the specimen surface was investigated. The result showed that with the increase of deposition time, the hydrophobic property enhanced gradually. The surface deposited for 7 h exhibited an optimum hydrophobic effect, which was characterized with a large water contact angle (WCA) of 154°, and the surface was rather rough and covered by a relatively uniform layer of micro-nano silver particles. The excellent hydrophobicity was attributed to a rough stratified microstructure along with the low surface energy. The electrochemical measurements showed that the existence of the superhydrophobic film can effectively enhance the corrosion resistance of Ti samples. PMID:28772987

Preparation of Superhydrophobic Film on Ti Substrate and Its Anticorrosion Property.

PubMed

Zhu, Min; Tang, Wenchuan; Huang, Luyao; Zhang, Dawei; Du, Cuiwei; Yu, Gaohong; Chen, Ming; Chowwanonthapunya, Thee

2017-06-08

Superhydrophobic films were fabricated on a titanium substrate with or without anodizing by using a self-assembling method. Firstly, the pretreatments of mechanical polishing/anodizing or mechanical polishing only were conducted, respectively. Subsequently, the preparation of polydopamine film layer, deposition of nano-silver particles, and post modification of 1H,1H,2H,2H-perfluorodecanethiol were performed on the surface of the pretreated substrate. The surface morphologies, compositions, wettability, and corrosion resistance of the films were investigated with scanning electron microscopy (SEM), energy-dispersive spectrometry (EDS), water contact angle measurements, and electrochemical tests, respectively. Meanwhile, the effect of the deposition time in the silver nitrate solution on the hydrophobicity of the specimen surface was investigated. The result showed that with the increase of deposition time, the hydrophobic property enhanced gradually. The surface deposited for 7 h exhibited an optimum hydrophobic effect, which was characterized with a large water contact angle (WCA) of 154°, and the surface was rather rough and covered by a relatively uniform layer of micro-nano silver particles. The excellent hydrophobicity was attributed to a rough stratified microstructure along with the low surface energy. The electrochemical measurements showed that the existence of the superhydrophobic film can effectively enhance the corrosion resistance of Ti samples.

Cyclic fatigue resistance of yttria-stabilized tetragonal zirconia polycrystals with hot isostatic press processing.

PubMed

Koyama, Taku; Sato, Toru; Yoshinari, Masao

2012-01-01

This study investigated the influence of surface roughness and cyclic loading on fatigue resistance in Y-TZP subjected to hot isostatic pressing (HIP). Fifty Y-TZP cylinders 3.0 mm in diameter were divided into Group A (polished by centerless method; TZP-CP) or Group B (blasted and acid-etched: TZP-SB150E). Twenty five cp-titanium cylinders (Ti-SB150E) were used as a control. Static and cyclic tests were carried out according to ISO 14801. The cyclic fatigue test was performed in distilled water at 37°C. Surface morphology and roughness as well as crystal phase on the surfaces were also evaluated. Fracture force under the static test was 1,765N (TZP-CP), 1,220N (TZP-SB150E), and 850 N (yield force, Ti-SB150E). Fracture values under the cyclic test decreased to approximately 70% of those under the static tests. These results indicate that HIPed Y-TZP with a 3.0-mm diameter has sufficient durability for application to dental implants.

Fabrication and characterization of flaky core-shell particles by magnetron sputtering silver onto diatomite

NASA Astrophysics Data System (ADS)

Wang, Yuanyuan; Zhang, Deyuan; Cai, Jun

2016-02-01

Diatomite has delicate porous structures and various shapes, making them ideal templates for microscopic core-shell particles fabrication. In this study, a new process of magnetron sputtering assisted with photoresist positioning was proposed to fabricate lightweight silver coated porous diatomite with superior coating quality and performance. The diatomite has been treated with different sputtering time to investigate the silver film growing process on the surface. The morphologies, constituents, phase structures and surface roughness of the silver coated diatomite were analyzed with SEM, EDS, XRD and AFM respectively. The results showed that the optimized magnetron sputtering time was 8-16 min, under which the diatomite templates were successfully coated with uniform silver film, which exhibits face centered cubic (fcc) structure, and the initial porous structures were kept. Moreover, this silver coating has lower surface roughness (RMS 4.513 ± 0.2 nm) than that obtained by electroless plating (RMS 15.692 ± 0.5 nm). And the infrared emissivity of coatings made with magnetron sputtering and electroless plating silver coated diatomite can reach to the lowest value of 0.528 and 0.716 respectively.

Micro arc oxidized HAp-TiO 2 nanostructured hybrid layers-part I: Effect of voltage and growth time

NASA Astrophysics Data System (ADS)

Abbasi, S.; Bayati, M. R.; Golestani-Fard, F.; Rezaei, H. R.; Zargar, H. R.; Samanipour, F.; Shoaei-Rad, V.

2011-05-01

Micro arc oxidation was employed to grow hydroxyapatite-TiO 2 nanostructured porous composite layers. The layers were synthesized on the titanium substrates in the electrolytes consisting of calcium acetate and sodium β-glycerophosphate salts under different applied voltages for various times. SEM and AFM investigations revealed a porous structure and rough surface where the pores size and the surface roughness were respectively determined as 70-650 nm and 9.8-12.7 nm depending on the voltage and time. Chemical composition and phase structure of the layers were evaluated using EDX, XPS, and XRD methods. The layers consisted of the hydroxyapatite, anatase, α-TCP, and calcium titanatephases with a varying fraction depending on the growth conditions. The hydroxyapatite crystalline size was also determined as ˜42 nm. The sample fabricated under the voltage of 350 V for 3 min exhibited the most appropriate Ca/P ratio (˜1.60) as well as the highest amount of the hydroxyapatite phase. This sample had a fine surface morphology and a high pores density.

3D Micro-topography of Transferred Laboratory and Natural Ice Crystal Surfaces Imaged by Cryo and Environmental Scanning Electron Microscopy

NASA Astrophysics Data System (ADS)

Magee, N. B.; Boaggio, K.; Bancroft, L.; Bandamede, M.

2015-12-01

Recent work has highlighted micro-scale roughness on the surfaces of ice crystals grown and imaged in-situ within the chambers of environmental scanning electron microscopes (ESEM). These observations appear to align with theoretical and satellite observations that suggest a prevalence of rough ice in cirrus clouds. However, the atmospheric application of the lab observations are indeterminate because the observations have been based only on crystals grown on substrates and in pure-water vapor environments. In this work, we present details and results from the development of a transfer technique which allows natural and lab-grown ice and snow crystals to be captured, preserved, and transferred into the ESEM for 3D imaging. Ice crystals were gathered from 1) natural snow, 2) a balloon-borne cirrus particle capture device, and 3) lab-grown ice crystals from a diffusion chamber. Ice crystals were captured in a pre-conditioned small-volume (~1 cm3) cryo-containment cell. The cell was then sealed closed and transferred to a specially-designed cryogenic dewer (filled with liquid nitrogen or crushed dry ice) for transport to a new Hitachi Field Emission, Variable Pressure SEM (SU-5000). The cryo-cell was then removed from the dewer and quickly placed onto the pre-conditioned cryo transfer stage attached to the ESEM (Quorum 3010T). Quantitative 3D topographical digital elevation models of ice surfaces are reported from SEM for the first time, including a variety of objective measures of statistical surface roughness. The surfaces of the transported crystals clearly exhibit signatures of mesoscopic roughening that are similar to examples of roughness seen in ESEM-grown crystals. For most transported crystals, the habits and crystal edges are more intricate that those observed for ice grown directly on substrates within the ESEM chamber. Portions of some crystals do appear smooth even at magnification greater than 1000x, a rare observation in our ESEM-grown crystals. The transported crystals hint at some significant differences in roughness morphology, but they do provide evidence that crystals grown in air/water mixtures and with minimal substrate influence also exhibit mesoscopic roughness with similarity to that observed in ESEM-grown crystals.

Thin film growth by 3D multi-particle diffusion limited aggregation model: Anomalous roughening and fractal analysis

NASA Astrophysics Data System (ADS)

Nasehnejad, Maryam; Nabiyouni, G.; Gholipour Shahraki, Mehran

2018-03-01

In this study a 3D multi-particle diffusion limited aggregation method is employed to simulate growth of rough surfaces with fractal behavior in electrodeposition process. A deposition model is used in which the radial motion of the particles with probability P, competes with random motions with probability 1 - P. Thin films growth is simulated for different values of probability P (related to the electric field) and thickness of the layer(related to the number of deposited particles). The influence of these parameters on morphology, kinetic of roughening and the fractal dimension of the simulated surfaces has been investigated. The results show that the surface roughness increases with increasing the deposition time and scaling exponents exhibit a complex behavior which is called as anomalous scaling. It seems that in electrodeposition process, radial motion of the particles toward the growing seeds may be an important mechanism leading to anomalous scaling. The results also indicate that the larger values of probability P, results in smoother topography with more densely packed structure. We have suggested a dynamic scaling ansatz for interface width has a function of deposition time, scan length and probability. Two different methods are employed to evaluate the fractal dimension of the simulated surfaces which are "cube counting" and "roughness" methods. The results of both methods show that by increasing the probability P or decreasing the deposition time, the fractal dimension of the simulated surfaces is increased. All gained values for fractal dimensions are close to 2.5 in the diffusion limited aggregation model.

Growth behavior and growth rate dependency in LEDs performance for Mg-doped a-plane GaN

NASA Astrophysics Data System (ADS)

Song, Keun-Man; Kim, Jong-Min; Lee, Dong-Hun; Shin, Chan-Soo; Ko, Chul-Gi; Kong, Bo-Hyun; Cho, Hyung-Koun; Yoon, Dae-Ho

2011-07-01

We investigated the influence of growth rate of Mg-doped a-plane GaN on the surface morphological and electrical properties, and the characteristics of InGaN-based nonpolar LEDs. Mg-doped a-plane GaN layers were grown on r-plane sapphire substrate by metalorganic chemical vapor deposition (MOCVD). Scanning electron microscopy (SEM), transmission electron microscopy (TEM) and cathode luminescence (CL) analysis exhibited that the surface morphology changed from stripe features with large triangular pits to rough and rugged surface with small asymmetric V-shape pits, as the growth rate increased. The Mg incorporation into a-plane GaN layers increased with increasing growth rate of Mg-doped a-plane GaN, while the activation efficiency of Mg dopants decreased in a-plane GaN. Additionally, it was found that operation voltage at 20 mA decreased in characteristics of LEDs, as the growth rate of Mg-doped a-plane GaN decreased. Meanwhile, the EL intensity of LEDs with p-GaN layers grown at higher growth rate was improved compared to that of LEDs with p-GaN layers grown at lower growth rate. Such an increase of EL intensity is attributed to the rougher surface morphology with increasing growth rate of Mg-doped a-plane GaN.

Laser Sintered Porous Ti-6Al-4V Implants Stimulate Vertical Bone Growth.

PubMed

Cheng, Alice; Cohen, David J; Kahn, Adrian; Clohessy, Ryan M; Sahingur, Kaan; Newton, Joseph B; Hyzy, Sharon L; Boyan, Barbara D; Schwartz, Zvi

2017-08-01

The objective of this study was to examine the ability of 3D implants with trabecular-bone-inspired porosity and micro-/nano-rough surfaces to enhance vertical bone ingrowth. Porous Ti-6Al-4V constructs were fabricated via laser-sintering and processed to obtain micro-/nano-rough surfaces. Male and female human osteoblasts were seeded on constructs to analyze cell morphology and response. Implants were then placed on rat calvaria for 10 weeks to assess vertical bone ingrowth, mechanical stability and osseointegration. All osteoblasts showed higher levels of osteocalcin, osteoprotegerin, vascular endothelial growth factor and bone morphogenetic protein 2 on porous constructs compared to solid laser-sintered controls. Porous implants placed in vivo resulted in an average of 3.1 ± 0.6 mm 3 vertical bone growth and osseointegration within implant pores and had significantly higher pull-out strength values than solid implants. New bone formation and pull-out strength was not improved with the addition of demineralized bone matrix putty. Scanning electron images and histological results corroborated vertical bone growth. This study indicates that Ti-6Al-4V implants fabricated by additive manufacturing to have porosity based on trabecular bone and post-build processing to have micro-/nano-surface roughness can support vertical bone growth in vivo, and suggests that these implants may be used clinically to increase osseointegration in challenging patient cases.

Atomic force microscopy and nanoindentation investigation of polydimethylsiloxane elastomeric substrate compliancy for various sputtered thin film morphologies.

PubMed

Maji, Debashis; Das, Soumen

2018-03-01

Crack free electrically continuous metal thin films over soft elastomeric substrates play an integral part in realization of modern day flexible bioelectronics and biosensors. Under nonoptimized deposition conditions, delamination, and/or cracking of the top film as well as the underlying soft substrate hinders optimal performance of these devices. Hence it is very important to understand and control not only the various deposition factors like power, time, or deposition pressure but also investigate the various interfacial physics playing a critical role in assuring thin film adhesion and substrate compliancy. In the present study, various nanomechanical information of the underlying substrate, namely, crack profile, average roughness, Young's modulus, and adhesion force were studied for uncracked and cracked polydimethylsiloxane (PDMS) surfaces along with pristine and conventional plasma treated PDMS samples as control. Quantification of the above parameters were done using three-dimensional surface profiler, scanning electron microscopy, nanoindentation, and atomic force microscopy techniques to elucidate the modulus range, average roughness, and adhesion force. Comparative analysis with control revealed remarkable similarity between increased modulus values, increased surface roughness, and reduced adhesion force accounting for reduced substrate compliancy and resulting in film cracking or buckling which are critical for development of various bioflexible devices. © 2017 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 106A: 725-737, 2018. © 2017 Wiley Periodicals, Inc.

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

PubMed Central

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

2015-01-01

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

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

Napari, Mari, E-mail: mari.napari@jyu.fi; Malm, Jari; Lehto, Roope

ZnO films were grown by atomic layer deposition at 35 °C on poly(methyl methacrylate) substrates using diethylzinc and water precursors. The film growth, morphology, and crystallinity were studied using Rutherford backscattering spectrometry, time-of-flight elastic recoil detection analysis, atomic force microscopy, scanning electron microscopy, and x-ray diffraction. The uniform film growth was reached after several hundreds of deposition cycles, preceded by the precursor penetration into the porous bulk and island-type growth. After the full surface coverage, the ZnO films were stoichiometric, and consisted of large grains (diameter 30 nm) with a film surface roughness up to 6 nm (RMS). The introduction of Al{sub 2}O{submore » 3} seed layer enhanced the initial ZnO growth substantially and changed the surface morphology as well as the crystallinity of the deposited ZnO films. Furthermore, the water contact angles of the ZnO films were measured, and upon ultraviolet illumination, the ZnO films on all the substrates became hydrophilic, independent of the film crystallinity.« less

Effect of implantoplasty on fracture resistance and surface roughness of standard diameter dental implants.

PubMed

Costa-Berenguer, Xavier; García-García, Marta; Sánchez-Torres, Alba; Sanz-Alonso, Mariano; Figueiredo, Rui; Valmaseda-Castellón, Eduard

2018-01-01

To assess the effect of implantoplasty on the fracture resistance, surface roughness, and macroscopic morphology of standard diameter (4.1 mm) external connection dental implants. An in vitro study was conducted in 20 screw-shaped titanium dental implants with an external connection. In 10 implants, the threads and surface were removed and polished with high-speed burs (implantoplasty), while the remaining 10 implants were used as controls. The final implant dimensions were recorded. The newly polished surface quality was assessed by scanning electron microscopy (SEM) and by 3D surface roughness analysis using a confocal laser microscope. Finally, all the implants were subjected to a mechanical pressure resistance test. A descriptive analysis of the data was made. Also, Student's t tests were employed to detect differences regarding the compression tests. Implantoplasty was carried out for a mean time of 10 min and 48 s (standard deviation (SD) of 1 min 22 s). Macroscopically, the resulting surface had a smooth appearance, although small titanium shavings and silicon debris were present. The final surface roughness (S a values 0.1 ± 0.02 μm) was significantly lower than that of the original (0.75 ± 0.08 μm S a ) (p = .005). There was minimal reduction in the implant's inner body diameter (0.19 ± 0.03 mm), and no statistically significant differences were found between the test and control implants regarding the maximum resistance force (896 vs 880 N, respectively). Implantoplasty, although technically demanding and time-consuming, does not seem to significantly alter fracture resistance of standard diameter external connection implants. A smooth surface with S a values below 0.1 μm can be obtained through the use of silicon polishers. A larger sample is required to confirm that implantoplasty does not significantly affect the maximum resistance force of standard diameter external connection implants. © 2017 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

The unique radar scattering properties of silicic lava flows and domes

NASA Technical Reports Server (NTRS)

Plaut, Jeffrey J.; Stofan, Ellen R.; Anderson, Steven W.; Crown, David A.

1995-01-01

Silicic (silica-rich) lava flows, such as rhyolite, rhyodacite, and dacite, possess unique physical properties primarily because of the relatively high viscosity of the molten lava. Silicic flows tend to be thicker than basaltic flows, and the resulting large-scale morphology is typically a steep-sided dome or flow lobe, with aspect ratios (height/length) sometimes approaching unity. The upper surfaces of silicic domes and flows are normally emplaced as relatively cool, brittle slabs that fracture as they are extruded from the central vent areas, and are then rafted away toward the flow margin as a brittle carapace above a more ductile interior layer. This mode of emplacement results in a surface with unique roughness characteristics, which can be well-characterized by multiparameter synthetic aperture radar (SAR) observations. In this paper, we examine the scattering properties of several silicic domes in the Inyo volcanic chain in the Eastern Sierra of California, using AIRSAR and TOPSAR data. Field measurements of intermediate-scale (cm to tens of m) surface topography and block size are used to assess the mechanisms of the scattering process, and to quantify the unique roughness characteristics of the flow surfaces.

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.

Titanium carbide nanoparticles reinforcing nickel matrix for improving nanohardness and fretting wear properties in wet conditions

NASA Astrophysics Data System (ADS)

Dănăilă, Eliza; Benea, Lidia; Caron, Nadège; Raquet, Olivier

2016-09-01

In this study Ni/nano-TiC functional composite coatings were produced by electro-codeposition of TiC nanoparticles (50 nm mean diameter) with nickel on 304L stainless steel support. Coatings were obtained from a Watts classical solution in which TiC nanoparticles were added. The surface morphology, chemical composition, structure, roughness and thickness, were evaluated in relation to the effect of TiC nanoparticles incorporation into Ni matrix. It was found that incorporation of TiC nanoparticles into the nickel matrix produces morphological changes in the deposit and increases the roughness. The fretting wear behavior in wet conditions of the obtained coatings was evaluated on a ball-on-plate configuration. To evaluate the wet fretting wear (tribocorrosion) behavior the open circuit potential was measured before, during and after the fretting tests at room temperature in the solution that simulates the primary water circuit of Pressurized Water Reactors. The results show that Ni/nano-TiC composite coatings exhibited a low friction coefficient, high nanohardness and fretting wear resistance in wet conditions compared with pure Ni coatings.

Superficial and Inner Examination of a Microwave-Irradiated Dental Acrylic Resin and Its Metal-Polymer Interface.

PubMed

Popescu, Marian C; Bita, Bogdan I; Tucureanu, Vasilica; Vasilache, Dan; Banu, Melania A; Avram, Andrei M; Giurescu-Dumitrescu, Raluca A

2018-02-01

The aim of this study is to conduct an extended surface and cross-section characterization of a denture base acrylic resin subjected to 500, 650, and 750 W microwave irradiation for 2, 3, and 5 min to assess its morphological modifications. A commercial heat-cured powder was polymerized according to the manufacturer's specifications and distributed into 20 circular samples. A stainless-steel wire was partially embedded in half of the discs, in order to investigate the metal-polymer interface. High-resolution scanning electron microscopy (SEM) imaging, white light interferometry, roughness measurements and Fourier transform infrared spectrometry were employed for morphological and structural evaluation of the irradiated polymer. Superficial adaptation was discovered after 5 min exposure at 500 W, 650 W, and 750 W, revealing significant roughness correction for 750 W. SEM characterization revealed the inner alteration of the resin for the 750 W protocol and a metal-polymer gap developed regardless of the irradiation conditions. The considerable temperature fluctuations that the samples were subject to during the experiments did not essentially change the poly(methyl-methacrylate) bond structure.

Lava flow field emplacement studies of Manua Ulu (Kilauea Volcano, Hawai'i, United States) and Venus, using field and remote sensing analyses

NASA Astrophysics Data System (ADS)

Byrnes, Jeffrey Myer

2002-04-01

This work examines lava emplacement processes by characterizing surface units using field and remote sensing analyses in order to understand the development of lava flow fields. Specific study areas are the 1969--1974 Mauna Ulu compound flow field, (Kilauea Volcano, Hawai'i, USA), and five lava flow fields on Venus: Turgmam Fluctus, Zipaltonal Fluctus, the Tuli Mons/Uilata Fluctus flow complex, the Var Mons flow field, and Mylitta Fluctus. Lava surface units have been examined in the field and with visible-, thermal-, and radar-wavelength remote sensing datasets for Mauna Ulu, and with radar data for the Venusian study areas. For the Mauna Ulu flow field, visible characteristics are related to color, glass abundance, and dm- to m-scale surface irregularities, which reflect the lava flow regime, cooling, and modification due to processes such as coalescence and inflation. Thermal characteristics are primarily affected by the abundance of glass and small-scale roughness elements (such as vesicles), and reflect the history of cooling, vesiculation and degassing, and crystallization of the lava. Radar characteristics are primarily affected by unit topography and fracturing, which are related to flow inflation, remobilization, and collapse, and reflect the local supply of lava during and after unit emplacement. Mauna Ulu surface units are correlated with pre-eruption topography, lack a simple relationship to the main feeder lava tubes, and are distributed with respect to their position within compound flow lobes and with distance from the vent. The Venusian lava flow fields appear to have developed through emplacement of numerous, thin, simple and compound flows, presumably over extended periods of time, and show a wider range of radar roughness than is observed at Mauna Ulu. A potential correlation is suggested between flow rheology and surface roughness. Distributary flow morphologies may result from tube-fed flows, and flow inflation is consistent with observed surface characteristics. Furthermore, the significance of inflation at Mauna Ulu and comparison of radar characteristics indicates that inflation may, in fact, be more prevalent on Venus than at Mauna Ulu. Although the Venusian flow fields display morphologies similar to those observed within terrestrial flow fields, the Venusian flow units are significantly larger.

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

PubMed

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

2010-09-01

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

Formation of pentacene wetting layer on the SiO2 surface and charge trap in the wetting layer.

PubMed

Kim, Chaeho; Jeon, D

2008-09-01

We studied the early-stage growth of vacuum-evaporated pentacene film on a native SiO(2) surface using atomic force microscopy and in-situ spectroscopic ellipsometry. Pentacene deposition prompted an immediate change in the ellipsometry spectra, but atomic force microscopy images of the early stage films did not show a pentacene-related morphology other than the decrease in the surface roughness. This suggested that a thin pentacene wetting layer was formed by pentacene molecules lying on the surface before the crystalline islands nucleated. Growth simulation based on the in situ spectroscopic ellipsometry spectra supported this conclusion. Scanning capacitance microscopy measurement indicated the existence of trapped charges in the SiO(2) and pentacene wetting layer.

Spontaneous recovery of superhydrophobicity on nanotextured surfaces

PubMed Central

Prakash, Suruchi; Xi, Erte; Patel, Amish J.

2016-01-01

Rough or textured hydrophobic surfaces are dubbed “superhydrophobic” due to their numerous desirable properties, such as water repellency and interfacial slip. Superhydrophobicity stems from an aversion of water for the hydrophobic surface texture, so that a water droplet in the superhydrophobic “Cassie state” contacts only the tips of the rough surface. However, superhydrophobicity is remarkably fragile and can break down due to the wetting of the surface texture to yield the “Wenzel state” under various conditions, such as elevated pressures or droplet impact. Moreover, due to large energetic barriers that impede the reverse transition (dewetting), this breakdown in superhydrophobicity is widely believed to be irreversible. Using molecular simulations in conjunction with enhanced sampling techniques, here we show that on surfaces with nanoscale texture, water density fluctuations can lead to a reduction in the free energetic barriers to dewetting by circumventing the classical dewetting pathways. In particular, the fluctuation-mediated dewetting pathway involves a number of transitions between distinct dewetted morphologies, with each transition lowering the resistance to dewetting. Importantly, an understanding of the mechanistic pathways to dewetting and their dependence on pressure allows us to augment the surface texture design, so that the barriers to dewetting are eliminated altogether and the Wenzel state becomes unstable at ambient conditions. Such robust surfaces, which defy classical expectations and can spontaneously recover their superhydrophobicity, could have widespread importance, from underwater operation to phase-change heat transfer applications. PMID:27140619

Effect of applied voltage on surface properties of anodised titanium in mixture of β-glycerophosphate (β-GP) and calcium acetate (CA)

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

Chuan, Lee Te, E-mail: gd130079@siswa.uthm.edu.my; Rathi, Muhammad Fareez Mohamad, E-mail: cd110238@siswa.uthm.edu.my; Abidin, Muhamad Yusuf Zainal, E-mail: cd110221@siswa.uthm.edu.my

Anodic oxidation is a surface modification method which combines electric field driven metal and oxygen ion diffusion for formation of oxide layer on the anode surface. This method has been widely used to modify the surface morphology of biomaterial especially titanium. This study aimed to investigate the effect of applied voltage on titanium. Specifically, the titanium foil was anodised in mixture of β-glycerophosphate disodium salt pentahydrate (β-GP) and calcium acetate monohydrate (CA) with different applied voltage (50-350 V), electrolyte concentration (0.04 M β-GP + 0.4 M CA), anodising time (10minutes) and current density (50 and 70 mA.cm{sup −2}) at room temperature. Surfacemore » oxide properties of anodised titanium were characterised by digital single-lens reflex camera (DSLR camera), field emission scanning electron microscope (FESEM) and atomic force microscopy (AFM). At lower applied voltage (≤150 V), surface of titanium foils were relatively smooth. With increasing applied voltage (≥250 V), the oxide layer became more porous and donut-shaped pores were formed on the surface of titanium foils. The AFM results indicated that the surface roughness of anodised titanium increases with increasing of applied voltage. The porous and rough surface is able to promote the osseointegration and reduce the suffering time of patient.« less

A pilot study of the marginal adaptation and surface morphology of glass-cermet cements.

PubMed

Chu, C H; King, N M; Lee, A M; Yiu, C K; Wei, S H

1996-07-01

This study investigated changes in the marginal adaptation and surface morphology of Ketac-Silver and Chelon-Silver glass-current cements over time. Dispersalloy amalgam was used as a control. Contralateral pairs of carious primary molars were restored with the test materials and amalgam. Clinical evaluations were scheduled at 12, 18, and 24 months after placement. Gold-plated replicas of the restorations were observed with scanning electron microscopy. Fractures and cracks in the surface of the Dispersalloy and Chelon-Silver increased the surface roughness; however, the damage was superficial and self-limiting in the Dispersalloy restorations, while in Chelon-Silver the fractures caused the material to break down in layers. A substantial quantity of pores, usually smaller than 50 microns in diameter, were observed throughout the surface of the Chelon-Silver restorations. The pores in the surface of Ketac-Silver were fewer and smaller. The incidence of cavomarginal breakdown increased with time. Chelon-Silver restorations had a higher rate of cavomarginal breakdown than did Ketac-Silver and Dispersalloy restorations up to 18 months. However, there was no statistically significant difference in the marginal adaptation of the three groups at 24 months.

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

Pecheva, E.; Fingarova, D.; Pramatarova, L.

Polycrystalline silicon (poly-Si) layers were functionalized through the growth of biomimetic hydroxyapatite (HA) on their surface. HA is the mineral component of bones and teeth and thus possesses excellent bioactivity and biocompatibility. MG-63 osteoblast-like cells were cultured on both HA-coated and un-coated poly-Si surfaces for 1, 3, 5 and 7 days and toxicity, proliferation and cell morphology were investigated. The results revealed that the poly-Si layers were bioactive and compatible with the osteoblast-like cells. Nevertheless, the HA coating improved the cell interactions with the poly-Si surfaces based on the cell affinity to the specific chemical composition of the bone-like HAmore » and/or to the higher HA roughness.« less

Polycrystalline Silicon: a Biocompatibility Assay

NASA Astrophysics Data System (ADS)

Pecheva, E.; Laquerriere, P.; Bouthors, Sylvie; Fingarova, D.; Pramatarova, L.; Hikov, T.; Dimova-Malinovska, D.; Montgomery, P.

2010-01-01

Polycrystalline silicon (poly-Si) layers were functionalized through the growth of biomimetic hydroxyapatite (HA) on their surface. HA is the mineral component of bones and teeth and thus possesses excellent bioactivity and biocompatibility. MG-63 osteoblast-like cells were cultured on both HA-coated and un-coated poly-Si surfaces for 1, 3, 5 and 7 days and toxicity, proliferation and cell morphology were investigated. The results revealed that the poly-Si layers were bioactive and compatible with the osteoblast-like cells. Nevertheless, the HA coating improved the cell interactions with the poly-Si surfaces based on the cell affinity to the specific chemical composition of the bone-like HA and/or to the higher HA roughness.

Deposition of Cubic AlN Films on MgO (100) Substrates by Laser Molecular Beam Epitaxy

NASA Astrophysics Data System (ADS)

Mo, Z. K.; Yang, W. J.; Weng, Y.; Fu, Y. C.; He, H.; Shen, X. M.

2017-12-01

Cubic AlN (c-AlN) films were deposited on MgO (100) substrates by laser molecular beam epitaxy (LMBE) technique. The crystal structure and surface morphology of deposited films with various laser pulse energy and substrate temperature were investigated. The results indicate that c-AlN films exhibit the (200) preferred orientation, showing a good epitaxial relationship with the substrate. The surface roughness of c-AlN films increases when the laser pulse energy and substrate temperature increase. The film grown at laser pulse energy of 150 mJ and substrate temperature of 700 °C shows the best crystalline quality and relatively smooth surface.

Effect of chlorhexidine-containing prophylactic agent on the surface characterization and frictional resistance between orthodontic brackets and archwires: an in vitro study

PubMed Central

2013-01-01

Background The purpose of this study was to assess the surface characterization and frictional resistance between stainless steel brackets and two types of orthodontic wires made of stainless steel and nickel-titanium alloys after immersion in a chlorhexidine-containing prophylactic agent. Methods Stainless steel orthodontic brackets with either stainless steel (SS) or heat-activated nickel-titanium (Ni-Ti) wires were immersed in a 0.2% chlorhexidine and an artificial saliva environment for 1.5 h. The frictional force was measured on a universal testing machine with a crosshead speed of 10 mm/min over a 5-mm of archwire. The surface morphology of bracket slots and surface roughness of archwires after immersion in chlorhexidine were also characterized using a scanning electron microscope (SEM) and an atomic force microscope (AFM), respectively. Results There was no significant difference in the frictional resistance values between SS and Ni-Ti wires immersed in either chlorhexidine or artificial saliva. The frictional resistance values for the SS and Ni-Ti wires immersed in 0.2% chlorhexidine solution were not significantly different from that inartificial saliva. No significant difference in the average surface roughness for both wires before (as-received) and after immersion in either chlorhexidine or artificial saliva was observed. Conclusions One-and-half-hour immersion in 0.2% chlorhexidine mouthrinse did not have significant influence on the archwires surface roughness or the frictional resistance between stainless steel orthodontic brackets and archwires made of SS and Ni-Ti. Based on these results, chlorhexidine-containing mouthrinses may be prescribed as non-destructive prophylactic agents on materials evaluated in the present study for orthodontic patients. PMID:24325758

Understanding Acoustic Cavitation Initiation by Porous Nanoparticles: Toward Nanoscale Agents for Ultrasound Imaging and Therapy.

PubMed

Yildirim, Adem; Chattaraj, Rajarshi; Blum, Nicholas T; Goodwin, Andrew P

2016-08-23

Ultrasound is widely applied in medical diagnosis and therapy due to its safety, high penetration depth, and low cost. In order to improve the contrast of sonographs and efficiency of the ultrasound therapy, echogenic gas bodies or droplets (with diameters from 200 nm to 10 µm) are often used, which are not very stable in the bloodstream and unable to penetrate into target tissues. Recently, it was demonstrated that nanobubbles stabilized by nanoparticles can nucleate ultrasound responsive microbubbles under reduced acoustic pressures, which is very promising for the development of nanoscale (<100 nm) ultrasound agents. However, there is still very little understanding about the effects of nanoparticle properties on the stabilization of nanobubbles and nucleation of acoustic cavitation by these nanobubbles. Here, a series of mesoporous silica nanoparticles with sizes around 100 nm but with different morphologies were synthesized to understand the effects of nanoparticle porosity, surface roughness, hydrophobicity, and hydrophilic surface modification on acoustic cavitation inception by porous nanoparticles. The chemical analyses of the nanoparticles showed that, while the nanoparticles were prepared using the same silica precursor (TEOS) and surfactant (CTAB), they revealed varying amounts of carbon impurities, hydroxyl content, and degrees of silica crosslinking. Carbon impurities or hydrophobic modification with methyl groups is found to be essential for nanobubble stabilization by mesoporous silica nanoparticles. The acoustic cavitation experiments in the presence of ethanol and/or bovine serum albumin (BSA) demonstrated that acoustic cavitation is predominantly nucleated by the nanobubbles stabilized at the nanoparticle surface not inside the mesopores. Finally, acoustic cavitation experiments with rough and smooth nanoparticles were suggested that a rough nanoparticle surface is needed to largely preserve surface nanobubbles after coating the surface with hydrophilic macromolecules, which is required for in vivo applications of nanoparticles.

Ultrasonic assessment of additive manufactured Ti-6Al-4V

NASA Astrophysics Data System (ADS)

Schehl, Norman; Kramb, Vicki; Dierken, Josiah; Aldrin, John; Schwalbach, Edwin; John, Reji

2018-04-01

Additive Manufacturing (AM) processes offer the potential for manufacturing cost savings and rapid insertion into service through production of near net shape components for complicated structures. Use of these parts in high reliability applications such as those in the aerospace industry will require nondestructive characterization methods to ensure post-process material quality in as-built condition. Ultrasonic methods can be used for this quality verification. Depending on the application, the service life of AM components can be sensitive to the part surface condition. The surface roughness and layered structure inherent to the electron-beam powder-bed fusion process necessitates new approaches to evaluate subsurface material integrity in its presence. Experimental methods and data analytics may improve the evaluation of as-built additively manufactured materials. This paper discusses the assessment of additively manufactured EBM Ti-6Al-4V panels using ultrasonic methods and the data analytics applied to evaluate material integrity. The assessment was done as an exploratory study as the discontinuities of interest in these test samples were not known when the measurements were performed. Water immersion ultrasonic techniques, including pulse-echo and through transmission with 10 MHz focused transducers, were used to explore the material integrity of as-built plates. Subsequent destructive mechanical tests of specimens extracted from the plates provided fracture locations indicating critical flaws. To further understand the effect of surface-roughness, an evaluation of ultrasonic response in the presence of as-built surfaces and with the surface removed was performed. The assessment of additive manufactured EBM Ti-6Al-4V panels with ultrasonic techniques indicated that ultrasonic energy was attenuated by the as-built surface roughness. In addition, feature detection was shown to be sensitive to experimental ultrasonic parameters and flaw morphology.

3D surface topography study of the biofunctionalized nanocrystalline Ti-6Zr-4Nb/Ca-P

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

Jakubowicz, J., E-mail: jaroslaw.jakubowicz@put.poznan.pl; Adamek, G.; Jurczyk, M.U.

2012-08-15

In this work surface of the sintered Ti-6Zr-4Nb nanocrystalline alloy was electrochemically biofunctionalized. The porous surface was produced by anodic oxidation in 1 M H{sub 3}PO{sub 4} + 2%HF electrolyte at 10 V for 30 min. Next the calcium-phosphate (Ca-P) layer was deposited, onto the formed porous surface, using cathodic potential - 5 V kept for 60 min in 0.042 M Ca(NO{sub 3}){sub 2} + 0.025 M (NH{sub 4}){sub 2}HPO{sub 4} + 0.1 M HCl electrolyte. The deposited Ca-P layer anchored in the pores. The biofunctionalized surface was studied by XRD, SEM and EDS. In vitro tests culture of normalmore » human osteoblast (NHOst) cells showed very good cells proliferation, colonization and multilayering. Using optical profiler, roughness and hybrid 3D surface topography parameters were estimated. Correlation between surface composition, morphology, roughness and biocompatibility results was done. It has been shown by us that surface with appropriate chemical composition and topography, after combined electrochemical anodic and cathodic surface treatment, supports osteoblast adhesion and proliferation. 3D topography measurements using optical profiler play a key role in the biomaterials surface analysis. - Highlights: Black-Right-Pointing-Pointer Nanocrystalline Ti-6Zr-4Nb/Ca-P material was produced for hard tissue implant applications. Black-Right-Pointing-Pointer Calcium-phosphate results in surface biofunctionalization. Black-Right-Pointing-Pointer The biofunctionalized surface shows good in-vitro behavior.« less

Topography evolution of 500 keV Ar(4+) ion beam irradiated InP(100) surfaces - formation of self-organized In-rich nano-dots and scaling laws.

PubMed

Sulania, Indra; Agarwal, Dinesh C; Kumar, Manish; Kumar, Sunil; Kumar, Pravin

2016-07-27

We report the formation of self-organized nano-dots on the surface of InP(100) upon irradiating it with a 500 keV Ar(4+) ion beam. The irradiation was carried out at an angle of 25° with respect to the normal at the surface with 5 different fluences ranging from 1.0 × 10(15) to 1.0 × 10(17) ions per cm(2). The morphology of the ion-irradiated surfaces was examined by atomic force microscopy (AFM) and the formation of the nano-dots on the irradiated surfaces was confirmed. The average size of the nano-dots varied from 44 ± 14 nm to 94 ± 26 nm with increasing ion fluence. As a function of the ion fluence, the variation in the average size of the nano-dots has a great correlation with the surface roughness, which changes drastically up to the ion fluence of 1.0 × 10(16) ions per cm(2) and attains almost a saturation level for further irradiation. The roughness and the growth exponent values deduced from the scaling laws suggest that the kinetic sputtering and the large surface diffusion steps of the atoms are the primary reasons for the formation of the self-organized nanodots on the surface. X-ray photo-electron spectroscopy (XPS) studies show that the surface stoichiometry changes with the ion fluence. With irradiation, the surface becomes more indium (In)-rich owing to the preferential sputtering of the phosphorus atoms (P) and the pure metallic In nano-dots evolve at the highest ion fluence. The cross-sectional scanning electron microscopy (SEM) analysis of the sample irradiated with the highest fluence showed the absence of the nanostructuring beneath the surface. The surface morphological changes at this medium energy ion irradiation are discussed in correlation with the low and high energy experiments to shed more light on the mechanism of the well separated nano-dot formation.

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

PubMed Central

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

2017-01-01

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

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

NASA Astrophysics Data System (ADS)

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

2017-03-01

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

Heterointerface engineering of broken-gap InAs/GaSb multilayer structures.

PubMed

Liu, Jheng-Sin; Zhu, Yan; Goley, Patrick S; Hudait, Mantu K

2015-02-04

Broken-gap InAs/GaSb strain balanced multilayer structures were grown by molecular beam epitaxy (MBE), and their structural, morphological, and band alignment properties were analyzed. Precise shutter sequence during the MBE growth process, enable to achieve the strain balanced structure. Cross-sectional transmission electron microscopy exhibited sharp heterointerfaces, and the lattice line extended from the top GaSb layer to the bottom InAs layer. X-ray analysis further confirmed a strain balanced InAs/GaSb multilayer structure. A smooth surface morphology with surface roughness of ∼0.5 nm was demonstrated. The effective barrier height -0.15 eV at the GaSb/InAs heterointerface was determined by X-ray photoelectron spectroscopy, and it was further corroborated by simulation. These results are important to demonstrate desirable characteristics of mixed As/Sb material systems for high-performance and low-power tunnel field-effect transistor applications.

Uniformity studies of inductively coupled plasma etching in fabrication of HgCdTe detector arrays

NASA Astrophysics Data System (ADS)

Bommena, R.; Velicu, S.; Boieriu, P.; Lee, T. S.; Grein, C. H.; Tedjojuwono, K. K.

2007-04-01

Inductively coupled plasma (ICP) chemistry based on a mixture of CH 4, Ar, and H II was investigated for the purpose of delineating HgCdTe mesa structures and vias typically used in the fabrication of second and third generation infrared photo detector arrays. We report on ICP etching uniformity results and correlate them with plasma controlling parameters (gas flow rates, total chamber pressure, ICP power and RF power). The etching rate and surface morphology of In-doped MWIR and LWIR HgCdTe showed distinct dependences on the plasma chemistry, total pressure and RF power. Contact stylus profilometry and cross-section scanning electron microscopy (SEM) were used to characterize the anisotropy of the etched profiles obtained after various processes and a standard deviation of 0.06 μm was obtained for etch depth on 128 x 128 format array vias. The surface morphology and the uniformity of the etched surfaces were studied by plan view SEM. Atomic force microscopy was used to make precise assessments of surface roughness.

The Effect of Aggressive Corrosion Mediums on the Microstructure and Properties of Mild Steel

NASA Astrophysics Data System (ADS)

Araoyinbo, A. O.; Salleh, M. A. A. Mohd; Rahmat, A.; Azmi, A. I.; Rahim, W. M. F. Wan Abd; Achitei, D. C.; Jin, T. S.

2018-06-01

Mild steel is known to be one of the major construction materials and have been extensively used in most chemical and material industries due to its interesting properties which can be easily altered to suit various application areas. In this research, mild steel is exposed to different aggressive mediums in order to observe the effect of these interactions on its surface morphology and properties. The mild steel used was cut into dimensions of 7 cm length and width of 3 cm. The aggressive mediums used are 100 mls of aqueous solution of hydrochloric acid, sodium hydroxide (40 g/L), and sodium chloride (35 g/L) at room temperature. The characterizations performed are the hardness test with the Rockwell hardness tester, the surface morphology by optical microscope, surface roughness and the weight loss from the immersion test. It was observed that the hardness value and the weight loss for the different cut samples of mild steel immersed in the different aggressive mediums reduces with prolong exposure and severe pitting form of corrosion was present on its surface.

Surface chemical structure for soft contact lenses as a function of polymer processing.

PubMed

Grobe, G L; Valint, P L; Ammon, D M

1996-09-01

The surface chemistry and topography of cast-molded Etafilcon-A and doubled-sided lathed Etafilcon-A soft contact lenses were determined to be significantly different. The variations in surface chemical and morphologic structure between the two lenses were the result of contact lens manufacturing methods. The surface of the cast-molded Etafilcon-A had a consistently less rough surface compared to the doubled sided lathed Etafilcon-A as determined by atomic force microscopy. The surface of the doubled sided lathed Etafilcon-A contained primarily silicone and wax contamination in addition to minute amounts of HEMA. The cast-molded Etafilcon-A had an elemental and chemical content which was consistent with the polymer stoichiometry. Contact angle wettability profiles revealed inherent wettability differences between the two lenses types. The cast-molded Etafilcon-A had an inherently greater water wettability, polarity, and critical surface tension. This means that these two lenses cannot be compared as similar or identical lens materials in terms of surface composition. The manufacturing method used to produce a soft contact lens directly determines the surface elemental and chemical structure as well as the morphology of the finished lens material. These results suggest possible differences in the clinical comfort, spoilage, and lubricity felt during patient wear.

Biomimetic fiber mesh scaffolds based on gelatin and hydroxyapatite nano-rods: Designing intrinsic skills to attain bone reparation abilities.

PubMed

Sartuqui, Javier; Gravina, A Noel; Rial, Ramón; Benedini, Luciano A; Yahia, L'Hocine; Ruso, Juan M; Messina, Paula V

2016-09-01

Intrinsic material skills have a deep effect on the mechanical and biological performance of bone substitutes, as well as on its associated biodegradation properties. In this work we have manipulated the preparation of collagenous derived fiber mesh frameworks to display a specific composition, morphology, open macroporosity, surface roughness and permeability characteristics. Next, the effect of the induced physicochemical attributes on the scaffold's mechanical behavior, bone bonding potential and biodegradability were evaluated. It was found that the scaffold microstructure, their inherent surface roughness, and the compression strength of the gelatin scaffolds can be modulated by the effect of the cross-linking agent and, essentially, by mimicking the nano-scale size of hydroxyapatite in natural bone. A clear effect of bioactive hydroxyapatite nano-rods on the scaffolds skills can be appreciated and it is greater than the effect of the cross-linking agent, offering a huge perspective for the upcoming progress of bone implant technology. Copyright © 2016 Elsevier B.V. All rights reserved.

Electron-beam patterned self-assembled monolayers as templates for Cu electrodeposition and lift-off

PubMed Central

She, Zhe; DiFalco, Andrea; Hähner, Georg

2012-01-01

Summary Self-assembled monolayers (SAMs) of 4'-methylbiphenyl-4-thiol (MBP0) adsorbed on polycrystalline gold substrates served as templates to control electrochemical deposition of Cu structures from acidic solution, and enabled the subsequent lift-off of the metal structures by attachment to epoxy glue. By exploiting the negative-resist behaviour of MBP0, the SAM was patterned by means of electron-beam lithography. For high deposition contrast a two-step procedure was employed involving a nucleation phase around −0.7 V versus Cu2+/Cu and a growth phase at around −0.35 V versus Cu2+/Cu. Structures with features down to 100 nm were deposited and transferred with high fidelity. By using substrates with different surface morphologies, AFM measurements revealed that the roughness of the substrate is a crucial factor but not the only one determining the roughness of the copper surface that is exposed after lift-off. PMID:22428101

T-Shaped Indan-1,3-dione derivatives as promising electron donors for bulk heterojunction small molecule solar cell

NASA Astrophysics Data System (ADS)

Adhikari, Tham; Solanke, Parmeshwar; Pathak, Dinesh; Wagner, Tomas; Bureš, Filip; Reed, Tyler; Nunzi, Jean-Michel

2017-07-01

We report on the photovoltaic performance of novel T-Shaped Indan-1,3-dione derivatives as donors in a solution processed bulk heterojunction solar cells. Small molecule bulk heterojunction solar cells of these molecules with [6,6]-phenyl-C61-butyric acid methyl ester (PC61BM) were fabricated and characterized. The preliminary characterization of these devices yielded a PCE of 0.24% and 0.33% for two separate derivatives. These low power conversion efficiencies were attributed to a high surface roughness with a large number of dewetting spots. Doping with 10% Polystyrene in the Indan-1,3-dione derivatives decreases surface roughness and dewetting spots thereby improving the efficiency of the devices. Efficiency of the devices was found as 0.39% and 0.51% for two derivatives after doping with polystyrene. The charge transfer mechanism was studied with photoluminescence quenching. The morphology and packing behavior of molecules were further studied using Atomic Force Microscopy (AFM) and X-ray diffraction (XRD).

Piezoelectricity of green carp scales

NASA Astrophysics Data System (ADS)

Jiang, H. Y.; Yen, F.; Huang, C. W.; Mei, R. B.; Chen, L.

2017-04-01

Piezoelectricity takes part in multiple important functions and processes in biomaterials often vital to the survival of organisms. Here, we investigate the piezoelectric properties of fish scales of green carp by directly examining their morphology at nanometer levels. Two types of regions are found to comprise the scales, a smooth one and a rough one. The smooth region is comprised of a ridge and trough pattern and the rough region characterized by a flat base with an elevated mosaic of crescents. Piezoelectricity is found on the ridges and base regions of the scales. From clear distinctions between the composition of the inner and outer surfaces of the scales, we identify the piezoelectricity to originate from the presence of hydroxyapatite which only exists on the surface of the fish scales. Our findings reveal a different mechanism of how green carp are sensitive to their surroundings and should be helpful to studies related to the electromechanical properties of marine life and the development of bio-inspired materials.

Simulation study of temperature-dependent diffusion behaviors of Ag/Ag(001) at low substrate temperature

NASA Astrophysics Data System (ADS)

Cai, Danyun; Mo, Yunjie; Feng, Xiaofang; He, Yingyou; Jiang, Shaoji

2017-06-01

In this study, a model based on the First Principles calculations and Kinetic Monte Carlo simulation were established to study the growth characteristic of Ag thin film at low substrate temperature. On the basis of the interaction between the adatom and nearest-neighbor atoms, some simplifications and assumptions were made to categorize the diffusion behaviors of Ag adatoms on Ag(001). Then the barriers of all possible diffusion behaviors were calculated using the Climbing Image Nudged Elastic Band method (CI-NEB). Based on the Arrhenius formula, the morphology variation, which is attributed to the surface diffusion behaviors during the growth, was simulated with a temperature-dependent KMC model. With this model, a non-monotonic relation between the surface roughness and the substrate temperature (decreasing from 300 K to 100 K) were discovered. The analysis of the temperature dependence on diffusion behaviors presents a theoretical explanation of diffusion mechanism for the non-monotonic variation of roughness at low substrate temperature.

Structural changes of a-CNx thin films induced by thermal annealing

NASA Astrophysics Data System (ADS)

Aziz, Siti Aisyah Abd; Awang, Rozidawati

2018-04-01

In this work, amorphous carbon nitride (a-CNx) thin films were deposited by radio frequency plasma enhanced chemical vapor deposition (RF-PECVD) technique at different RF powers of 60, 70, 80, 90 and 100 W for 30 min. These films were prepared using a mixture of acetylene (C2H2) at 20 sccm and nitrogen (N2) gases at 50 sccm. The films were then annealed at 400 °C in a quartz tube furnace in argon (Ar) gas. The chemical bondings of the film were analyzed by Fourier Transform Infra-red Spectroscopy (FTIR) while surface morphology and film roughness were determined by Atomic Force Microscopy (AFM). The FTIR analysis reveals that annealing resulted in the loss of C-H and C-N bonds and formation of graphitic sp2C cluster with the dissociation of N and C in the films. AFM indicates that the film surface becomes less rough which effectually enhances structural modifications and the rearrangement of the microstructure of the films after annealing.

Texture descriptions of lunar surface derived from LOLA data: Kilometer-scale roughness and entropy maps

NASA Astrophysics Data System (ADS)

Li, Bo; Ling, Zongcheng; Zhang, Jiang; Chen, Jian; Wu, Zhongchen; Ni, Yuheng; Zhao, Haowei

2015-11-01

The lunar global texture maps of roughness and entropy are derived at kilometer scales from Digital Elevation Models (DEMs) data obtained by Lunar Orbiter Laser Altimeter (LOLA) aboard on Lunar Reconnaissance Orbiter (LRO) spacecraft. We use statistical moments of a gray-level histogram of elevations in a neighborhood to compute the roughness and entropy value. Our texture descriptors measurements are shown in global maps at multi-sized square neighborhoods, whose length of side is 3, 5, 10, 20, 40 and 80 pixels, respectively. We found that large-scale topographical changes can only be displayed in maps with longer side of neighborhood, but the small scale global texture maps are more disorderly and unsystematic because of more complicated textures' details. Then, the frequency curves of texture maps are made out, whose shapes and distributions are changing as the spatial scales increases. Entropy frequency curve with minimum 3-pixel scale has large fluctuations and six peaks. According to this entropy curve we can classify lunar surface into maria, highlands, different parts of craters preliminarily. The most obvious textures in the middle-scale roughness and entropy maps are the two typical morphological units, smooth maria and rough highlands. For the impact crater, its roughness and entropy value are characterized by a multiple-ring structure obviously, and its different parts have different texture results. In the last, we made a 2D scatter plot between the two texture results of typical lunar maria and highlands. There are two clusters with largest dot density which are corresponded to the lunar highlands and maria separately. In the lunar mare regions (cluster A), there is a high correlation between roughness and entropy, but in the highlands (Cluster B), the entropy shows little change. This could be subjected to different geological processes of maria and highlands forming different landforms.

Aqueous chemical growth of free standing vertical ZnO nanoprisms, nanorods and nanodiskettes with improved texture co-efficient and tunable size uniformity

NASA Astrophysics Data System (ADS)

Ram, S. D. Gopal; Ravi, G.; Athimoolam, A.; Mahalingam, T.; Kulandainathan, M. Anbu

2011-12-01

Tuning the morphology, size and aspect ratio of free standing ZnO nanostructured arrays by a simple hydrothermal method is reported. Pre-coated ZnO seed layers of two different thicknesses (≈350 nm or 550 nm) were used as substrates to grow ZnO nanostructures for the study. Various parameters such as chemical ambience, pH of the solution, strength of the Zn2+ atoms and thickness of seed bed are varied to analyze their effects on the resultant ZnO nanostructures. Vertically oriented hexagonal nanorods, multi-angular nanorods, hexagonal diskette and popcorn-like nanostructures are obtained by altering the experimental parameters. All the produced nanostructures were analysed by X-ray powder diffraction analysis and found to be grown in the (002) orientation of wurtzite ZnO. The texture co-efficient of ZnO layer was improved by combining a thick seed layer with higher cationic strength. Surface morphological studies reveal various nanostructures such as nanorods, diskettes and popcorn-like structures based on various preparation conditions. The optical property of the closest packed nanorods array was recorded by UV-VIS spectrometry, and the band gap value simulated from the results reflect the near characteristic band gap of ZnO. The surface roughness profile taken from the Atomic Force Microscopy reveals a roughness of less than 320 nm.

Facile Synthesis of Uniform Virus-like Mesoporous Silica Nanoparticles for Enhanced Cellular Internalization

PubMed Central

2017-01-01

The low-efficiency cellular uptake property of current nanoparticles greatly restricts their application in the biomedical field. Herein, we demonstrate that novel virus-like mesoporous silica nanoparticles can easily be synthesized, showing greatly superior cellular uptake property. The unique virus-like mesoporous silica nanoparticles with a spiky tubular rough surface have been successfully synthesized via a novel single-micelle epitaxial growth approach in a low-concentration-surfactant oil/water biphase system. The virus-like nanoparticles’ rough surface morphology results mainly from the mesoporous silica nanotubes spontaneously grown via an epitaxial growth process. The obtained nanoparticles show uniform particle size and excellent monodispersity. The structural parameters of the nanoparticles can be well tuned with controllable core diameter (∼60–160 nm), tubular length (∼6–70 nm), and outer diameter (∼6–10 nm). Thanks to the biomimetic morphology, the virus-like nanoparticles show greatly superior cellular uptake property (invading living cells in large quantities within few minutes, <5 min), unique internalization pathways, and extended blood circulation duration (t1/2 = 2.16 h), which is much longer than that of conventional mesoporous silica nanoparticles (0.45 h). Furthermore, our epitaxial growth strategy can be applied to fabricate various virus-like mesoporous core–shell structures, paving the way toward designed synthesis of virus-like nanocomposites for biomedicine applications. PMID:28852697

Effect of 10% Strontium Chloride and 5% Potassium Nitrate with Fluoride on Bleached Bovine Enamel.

PubMed

Alencar, Cristiane de Melo; Pedrinha, Victor Feliz; Araújo, Jesuína Lamartine Nogueira; Esteves, Renata Antunes; Silva da Silveira, Ana Daniela; Silva, Cecy Martins

2017-01-01

Dental whitening has been increasingly sought out to improve dental aesthetics, but may cause chemical and morphological changes in dental enamel surfaces. This study evaluated in vitro the effect of 10% strontium chloride and 5% potassium nitrate with fluoride on bovine enamel, through tristimulus colorimetry, Knoop microhardness (KHN), and roughness after bleaching with 35% hydrogen peroxide (HP). The specimens were divided into three groups (n=15): GControl received bleaching treatment with 35% HP; GNitrate received bleaching with 35% HP followed by the application of 5% potassium nitrate with 2% sodium fluoride; and GStrontium received bleaching with 35% HP followed by the application of 10% strontium chloride on the enamel. Next, five specimens of each experimental group were subjected to KHN and tristimulus colorimetry tests, and 10 specimens were subjected to surface roughness (SR) tests. The values obtained for the different groups were compared through analysis of variance (ANOVA) followed by a post-hoc Tukey-Kramer test in addition to Student's T-test for paired data. In the intergroup comparison, KHN final differed statistically ( p <0.05). The mean SR final of the experimental groups differed statistically from the GControl group ( p <0.05). In addition, the groups did not differ in color variation ( p >0.05). 10% strontium chloride and 5% potassium nitrate combined with 2% fluoride downplayed morphological changes to the enamel, without interfering with the effectiveness of the bleaching process.

Investigation of absorptance and emissivity of thermal control coatings on Mg–Li alloys and OES analysis during PEO process

PubMed Central

Yao, Zhongping; Xia, Qixing; Ju, Pengfei; Wang, Jiankang; Su, Peibo; Li, Dongqi; Jiang, Zhaohua

2016-01-01

Thermal control ceramic coatings on Mg–Li alloys have been successfully prepared in silicate electrolyte system by plasma electrolytic oxidation (PEO) method. The PEO coatings are mainly composed of crystallized Mg2SiO4 and MgO, which have typical porous structure with some bulges on the surface; OES analysis shows that the plasma temperature, which is influenced by the technique parameters, determines the formation of the coatings with different crystalline phases and morphologies, combined with “quick cooling effect” by the electrolyte; and the electron concentration is constant, which is related to the electric spark breakdown, determined by the nature of the coating and the interface of coating/electrolyte. Technique parameters influence the coating thickness, roughness and surface morphology, but do not change the coating composition in the specific PEO regime, and therefore the absorptance (αS) and emissivity (ε) of the coatings can be adjusted by the technique parameters through changing thickness and roughness in a certain degree. The coating prepared at 10 A/dm2, 50 Hz, 30 min and 14 g/L Na2SiO3 has the minimum value of αS (0.35) and the maximum value of ε (0.82), with the balance temperature of 320 K. PMID:27383569

Excimer laser-induced hydrohynamical effects and surface modifications on silicon carbide

NASA Astrophysics Data System (ADS)

Nicolas, Gines; Autric, Michel

1996-04-01

The use of lasers in many applications requires an understanding and control of the fundamental processes involved during the laser radiation-material interaction. The importance and the duration of the phenomena involved (optical, thermal, mechanical, electromagnetic, radiative) depend on parameters such as the power density of the laser radiation, the nature and the surface morphology of the material, the surrounding gas and the wavelength of the radiation. A part of the incident energy is reflected by the surface, while the remaining quantity of this energy is absorbed by the material. This incident energy contributes to heating, melting, vaporization and plasma formation if the laser intensity is sufficiently high. The present study is devoted to the ceramic material irradiation in air by an excimer laser at a wavelength of 248 nm and a pulse duration of 20 ns. The objective is to understand the different phenomena induced by radiation and to improve mechanical properties of the surface. Presented results concern the dynamics of plasmas and shock waves, plus surface modifications (porosity, roughness, composition changes) on silicon carbide samples (SiC). A part of the study has resulted in the characterization of the flow created in front of the sample revealing different hydrodynamical regimes. Visualizations of the luminous plasma front and shock waves have been obtained using a fast electronic camera IMACON 790 and a ICCD camera. These optical devices have permitted us to observe simultaneously the formation and expansion of different fronts (plasma and shock waves) propagating into the surrounding gas. The results have been compared to the theory. Complex structures inside the plume have been observed inducing a turbulence phenomena some milliseconds after the irradiation. On the other hand, the surface morphology has been characterized by observations with a scanning electron microscope (SEM) showing important modifications of the morphology according to the energy density and number of pulses applied. A decrease of surface porosity is revealed using image processing technique. This improvement is accompanied with an increase of roughness which has been measured by mechanical profilometry and might be detrimental for friction applications. In addition, an analysis of the material in depth by Auger electron spectroscopy (AES) has shown chemical composition changes (an increase in the percentage of silicon) in the zone irradiated.

Impact of nanocrystal spray deposition on inorganic solar cells.

PubMed

Townsend, Troy K; Yoon, Woojun; Foos, Edward E; Tischler, Joseph G

2014-05-28

Solution-synthesized inorganic cadmium telluride nanocrystals (∼4 nm; 1.45 eV band gap) are attractive elements for the fabrication of thin-film-based low-cost photovoltaic (PV) devices. Their encapsulating organic ligand shell enables them to be easily dissolved in organic solvents, and the resulting solutions can be spray-cast onto indium-tin oxide (ITO)-coated glass under ambient conditions to produce photoactive thin films of CdTe. Following annealing at 380 °C in the presence of CdCl2(s) and evaporation of metal electrode contacts (glass/ITO/CdTe/Ca/Al), Schottky-junction PV devices were tested under simulated 1 sun conditions. An improved PV performance was found to be directly tied to control over the film morphology obtained by the adjustment of spray parameters such as the solution concentration, delivery pressure, substrate distance, and surface temperature. Higher spray pressures produced thinner layers (<60 nm) with lower surface roughness (<200 nm), leading to devices with improved open-circuit voltages (Voc) due to decreased surface roughness and higher short-circuit current (Jsc) as a result of enhanced annealing conditions. After process optimization, spray-cast Schottky devices rivaled those prepared by conventional spin-coating, showing Jsc = 14.6 ± 2.7 mA cm(-2), Voc = 428 ± 11 mV, FF = 42.8 ± 1.4%, and Eff. = 2.7 ± 0.5% under 1 sun illumination. This optimized condition of CdTe spray deposition was then applied to heterojunction devices (ITO/CdTe/ZnO/Al) to reach 3.0% efficiency after light soaking under forward bias. The film thickness, surface morphology, and light absorption were examined with scanning electron microscopy, optical profilometry, and UV/vis spectroscopy.

Effects and mechanism on Kapton film under ozone exposure in a ground near space simulator

NASA Astrophysics Data System (ADS)

Wei, Qiang; Yang, Guimin; Liu, Gang; Jiang, Haifu; Zhang, Tingting

2018-05-01

The effect on aircraft materials in the near space environment is a key part of air-and-space integration research. Ozone and aerodynamic fluids are important organizational factors in the near space environment and both have significant influences on the performance of aircraft materials. In the present paper a simulated ozone environment was used to test polyimide material that was rotated at the approximate velocity of 150-250 m/s to form an aerodynamic fluid field. The goal was to evaluate the performance evolution of materials under a comprehensive environment of ozone molecular corrosion and aerodynamic fluids. The research results show that corrosion and sputtering by ozone molecules results in Kapton films exhibiting a rugged "carpet-like" morphology exhibits an increase in surface roughness. The morphology after ozone exposure led to higher surface roughness and an increase in surface optical diffuse reflection, which is expressed by the lower optical transmittance and the gradual transition from light orange to brown. The mass loss test, XPS, and FTIR analysis show that the molecular chains on the surface of the Kapton film are destroyed resulting in Csbnd C bond breaking to form small volatile molecules such as CO2 or CO, which are responsible for a linear increase in mass loss per unit area. The Csbnd N and Csbnd O structures exhibit weakening tendency under ozone exposure. The present paper explores the evaluation method for Kapton's adaptability under the ozone exposure test in the near space environment, and elucidates the corrosion mechanism and damage mode of the polyimide material under the combined action of ozone corrosion and the aerodynamic fluid. This work provides a methodology for studying materials in the near-space environment.

UV photofunctionalization promotes nano-biomimetic apatite deposition on titanium

PubMed Central

Saita, Makiko; Ikeda, Takayuki; Yamada, Masahiro; Kimoto, Katsuhiko; Lee, Masaichi Chang-Il; Ogawa, Takahiro

2016-01-01

Background Although biomimetic apatite coating is a promising way to provide titanium with osteoconductivity, the efficiency and quality of deposition is often poor. Most titanium implants have microscale surface morphology, and an addition of nanoscale features while preserving the micromorphology may provide further biological benefit. Here, we examined the effect of ultraviolet (UV) light treatment of titanium, or photofunctionalization, on the efficacy of biomimetic apatite deposition on titanium and its biological capability. Methods and results Micro-roughed titanium disks were prepared by acid-etching with sulfuric acid. Micro-roughened disks with or without photofunctionalization (20-minute exposure to UV light) were immersed in simulated body fluid (SBF) for 1 or 5 days. Photofunctionalized titanium disks were superhydrophilic and did not form surface air bubbles when immersed in SBF, whereas non-photofunctionalized disks were hydrophobic and largely covered with air bubbles during immersion. An apatite-related signal was observed by X-ray diffraction on photofunctionalized titanium after 1 day of SBF immersion, which was equivalent to the one observed after 5 days of immersion of control titanium. Scanning electron microscopy revealed nodular apatite deposition in the valleys and at the inclines of micro-roughened structures without affecting the existing micro-configuration. Micro-roughened titanium and apatite-deposited titanium surfaces had similar roughness values. The attachment, spreading, settling, proliferation, and alkaline phosphate activity of bone marrow-derived osteoblasts were promoted on apatite-coated titanium with photofunctionalization. Conclusion UV-photofunctionalization of titanium enabled faster deposition of nanoscale biomimetic apatite, resulting in the improved biological capability compared to the similarly prepared apatite-deposited titanium without photofunctionalization. Photofunctionalization-assisted biomimetic apatite deposition may be a novel method to effectively enhance micro-roughened titanium surfaces without altering their microscale morphology. PMID:26834469

Micro/nano hierarchical structured titanium treated by NH4OH/H2O2 for enhancing cell response

PubMed Central

Yuan, Xin; Kang, Yi; Zuo, Jun; Xie, Youneng; Ma, Li; Ren, Xuelei; Bian, Zeyu; Zhou, Kechao; Wang, Xiyang; Yu, Zhiming

2018-01-01

In this paper, two kinds of titanium surfaces with novel micro/nano hierarchical structures, namely Etched (E) surface and Sandblast and etched (SE) surface, were successfully fabricated by NH4OH and H2O2 mixture. And their cellular responses of MG63 were investigated compared with Sandblast and acid-etching (SLA) surface. Scanning electron microscope (SEM), Surface profiler, X-ray photoelectron spectroscopy (XPS), and Contact angle instrument were employed to assess the surface morphologies, roughness, chemistry and wettability respectively. Hierarchical structures with micro holes of 10–30 μm in diameter and nano pits of tens of nanometers in diameter formed on both E and SE surfaces. The size of micro holes is very close to osteoblast cell, which makes them wonderful beds for osteoblast. Moreover, these two kinds of surfaces possess similar roughness and superior hydrophilicity to SLA. Reactive oxygen species were detected on E and SE surface, and thus considerable antimicrobial performance and well fixation can be speculated on them. The cell experiments also demonstrated a boost in cell attachment, and that proliferation and osteogenic differentiation were achieved on them, especially on SE surface. The results indicate that the treatment of pure titanium with H2O2/NH4OH is an effective technique to improve the initial stability of implants and enhance the osseointegration, which may be a promising surface treatment to titanium implant. PMID:29723214

The VHCF experimental investigation of FV520B-I with surface roughness Ry

NASA Astrophysics Data System (ADS)

Wang, J. L.; Zhang, Y. L.; Ding, M. C.; Zhao, Q. C.

2018-05-01

Different surface roughness type (Ra and Ry) has different effect on the VHCF failure and life. Ra is widely employed as the quantitative expression of the surface roughness, but there are few fatigue failure mechanism analysis and experimental study under surface roughness Ry. The VHCF experiment is conducted out using the specimen with different surface roughness values. The surface roughness Ry is employed as the major research object to investigate the relationship and distribution tendency between the Ry, fatigue life and the distance between internal inclusion and surface, and a new VHCF failure character is proposed.

Smoothed particle hydrodynamics study of the roughness effect on contact angle and droplet flow

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

Shigorina, Elena; Kordilla, Jannes; Tartakovsky, Alexandre M.

We employ a pairwise force Smoothed Particle Hydrodynamics (PF-SPH) model to simulate sessile and transient droplets on rough hydrophobic and hydrophilic surfaces. PF-SPH allows for modeling of free surface flow without discretizing the air phase, which is achieved by imposing the surface tension and dynamic contact angles with pairwise interaction forces. We use the PF-SPH model to study the effect of surface roughness and microscopic contact angle on the effective contact angle and droplet dynamics. In the first part of this work, we investigate static contact angles of sessile droplets on rough surfaces in a shape of a sinusoidal functionmore » and made of rectangular bars placed on top of a flat surface. We find that the effective static contact angles of Cassie and Wenzel droplets on a rough surface are greater than the corresponding microscale static contact angles. As a result, microscale hydrophobic rough surfaces also show effective hydrophobic behavior. On the other hand, microscale hydrophilic surfaces may be macroscopically hydrophilic or hydrophobic, depending on the type of roughness. Next, we study the impact of the roughness orientation (i.e., an anisotropic roughness) and surface inclination on droplet flow velocities. Simulations show that droplet flow velocities are lower if the surface roughness is oriented perpendicular to the flow direction. If the predominant elements of surface roughness are in alignment with the flow direction, the flow velocities increase compared to smooth surfaces, which can be attributed to the decrease in fluid-solid contact area similar to the classical lotus effect. We demonstrate that linear scaling relationships between Bond and capillary number for droplet flow on flat surfaces also hold for flow on rough surfaces.« less

Dynamics and early post-tsunami evolution of floating marine debris near Fukushima Daiichi

NASA Astrophysics Data System (ADS)

Matthews, John Philip; Ostrovsky, Lev; Yoshikawa, Yutaka; Komori, Satoru; Tamura, Hitoshi

2017-08-01

The devastating tsunami triggered by the Tōhoku-Oki earthquake of 11 March 2011 caused a crisis at the Fukushima Daiichi nuclear power station where it overtopped the seawall defences. On retreating, the tsunami carried loose debris and wreckage seaward and marshalled buoyant material into extensive plumes. Widespread concern over the fate of these and numerous other Tōhoku tsunami depositions prompted attempts to simulate debris dispersion throughout the wider Pacific. However, the effects of locally perturbed wind and wave fields, active Langmuir circulation and current-induced attrition determine a complex and poorly understood morphology for large floating agglomerations. Here we show that the early post-tsunami evolution of marine-debris plumes near Fukushima Daiichi was also shaped by near-surface wind modifications that took place above relatively calm (lower surface roughness) waters covered by surface films derived from oil and other contaminants. High-spatial-resolution satellite tracking reveals faster-than-expected floating-debris motions and invigorated plume evolution within these regions, while numerical modelling of turbulent air flow over the low-drag, film-covered surface predicts typically metre-per-second wind strengthening at centimetric heights, sufficient to explain the observed debris-speed increases. Wind restructuring probably stimulates the dispersion of flotsam from both biological and anthropogenic sources throughout a global ocean of highly variable surface roughness.

Role of rough surface topography on gas slip flow in microchannels.

PubMed

Zhang, Chengbin; Chen, Yongping; Deng, Zilong; Shi, Mingheng

2012-07-01

We conduct a lattice Boltzmann simulation of gas slip flow in microchannels incorporating rough surface effects as characterized by fractal geometry with a focus on gas-solid interaction. The gas slip flow in rough microchannels, which is characterized by Poiseuille number and mass flow rate, is evaluated and compared with smooth microchannels. The effects of roughness height, surface fractal dimension, and Knudsen number on slip behavior of gas flow in microchannels are all investigated and discussed. The results indicate that the presence of surface roughness reduces boundary slip for gas flow in microchannels with respect to a smooth surface. The gas flows at the valleys of rough walls are no-slip while velocity slips are observed over the top of rough walls. We find that the gas flow behavior in rough microchannels is insensitive to the surface topography irregularity (unlike the liquid flow in rough microchannels) but is influenced by the statistical height of rough surface and rarefaction effects. In particular, decrease in roughness height or increase in Knudsen number can lead to large wall slip for gas flow in microchannels.

Ultrasonic cavitation erosion of 316L steel weld joint in liquid Pb-Bi eutectic alloy at 550°C.

PubMed

Lei, Yucheng; Chang, Hongxia; Guo, Xiaokai; Li, Tianqing; Xiao, Longren

2017-11-01

Liquid lead-bismuth eutectic alloy (LBE) is applied in the Accelerator Driven transmutation System (ADS) as the high-power spallation neutron targets and coolant. A 19.2kHz ultrasonic device was deployed in liquid LBE at 550°C to induce short and long period cavitation erosion damage on the surface of weld joint, SEM and Atomic force microscopy (AFM) were used to map out the surface properties, and Energy Dispersive Spectrometer (EDS) was applied to the qualitative and quantitative analysis of elements in the micro region of the surface. The erosion mechanism for how the cavitation erosion evolved by studying the element changes, their morphology evolution, the surface hardness and the roughness evolution, was proposed. The results showed that the pits, caters and cracks appeared gradually on the erode surface after a period of cavitation. The surface roughness increased along with exposure time. Work hardening by the bubbles impact in the incubation stage strengthened the cavitation resistance efficiently. The dissolution and oxidation corrosion and cavitation erosion that simultaneously happened in liquid LBE accelerated corrosion-erosion process, and these two processes combined to cause more serious damage on the material surface. Contrast to the performance of weld metal, base metal exhibited a much better cavitation resistance. Copyright © 2017. Published by Elsevier B.V.

Morphology control of zinc regeneration for zinc-air fuel cell and battery

NASA Astrophysics Data System (ADS)

Wang, Keliang; Pei, Pucheng; Ma, Ze; Xu, Huachi; Li, Pengcheng; Wang, Xizhong

2014-12-01

Morphology control is crucial both for zinc-air batteries and for zinc-air fuel cells during zinc regeneration. Zinc dendrite should be avoided in zinc-air batteries and zinc pellets are yearned to be formed for zinc-air fuel cells. This paper is mainly to analyze the mechanism of shape change and to control the zinc morphology during charge. A numerical three-dimensional model for zinc regeneration is established with COMSOL software on the basis of ionic transport theory and electrode reaction electrochemistry, and some experiments of zinc regeneration are carried out. The deposition process is qualitatively analyzed by the kinetics Monte Carlo method to study the morphological change from the electrocrystallization point of view. Morphological evolution of deposited zinc under different conditions of direct currents and pulse currents is also investigated by simulation. The simulation shows that parametric variables of the flowing electrolyte, the surface roughness and the structure of the electrode, the charging current and mode affect morphological evolution. The uniform morphology of deposited zinc is attained at low current, pulsating current or hydrodynamic electrolyte, and granular morphology is obtained by means of an electrode of discrete columnar structure in combination with high current and flowing electrolyte.

Linking glacial sliding and rock type via spectral roughness and spatial patterns of fractures on glaciated bedrock in the Teton Range, Wyoming, USA

NASA Astrophysics Data System (ADS)

Dodson, Z.; Ward, D.

2017-12-01

Topographic roughness is an essential control on the basal movement of temperate glaciers. Glaciers move by regelation over small-scale roughness and by enhanced ice deformation over large-scale roughness. There is a transitional wavelength of 0.1 to 1 m that has the most resistance to basal sliding. Preexisting fractures in bedrock are known to affect the rate and spatial pattern of glacial erosion. However, few studies have quantified the relationship between fractures and bed roughness at various scales or shown how these features change downvalley and on different bedrock types. Here, we present results that relate fracture pattern and micro-roughness of glaciated surfaces in the Teton Range of Wyoming. The study area includes Alaska Basin and Darby Canyon, which are adjacent valleys on the western side of the range. The valley floor of Alaska Basin is quartz monzonite, while that of Darby Canyon is dolomite. Both exhibit regional fractures, however, unlike the quartz monzonite, the dolomite has joints associated with bedding planes that dip roughly parallel to the valley floor. In satellite imagery, it is evident that the large-scale roughness in the valleys differ, with Darby Canyon having a smooth bed relative to the bumpy bed in Alaska Basin. Our aim is to quantify the small-scale roughness at cm-level resolution using Structure-from-Motion (SfM) photogrammetry. Our hypothesis is that the roughness will differ between the valleys and be related to fracture spacing within each rock type. We will test this using a Fourier spectral analysis of high-resolution DEMs made by SfM to identify the dominant wavelengths present in the previously glaciated surfaces, paired with field measurements of fracture spacing and orientation. If rock type is the main control in bed roughness, we predict that the dominant low-frequency wavelength will be similar to the spacing of major regional fractures, and the high-frequency spectral modes will be similar to the spacing of smaller local fractures. Alternatively, if the results show that the dominant wavelengths differ from the pattern of fractures or change with position downvalley in one or both of the valleys, then this implies that the glacier properties, such as flow rate and thickness, are what modulate bedrock erosion and fractures are less significant to morphology evolution.

Super-hydrophobic coatings based on non-solvent induced phase separation during electro-spraying.

PubMed

Gao, Jiefeng; Huang, Xuewu; Wang, Ling; Zheng, Nan; Li, Wan; Xue, Huaiguo; Li, Robert K Y; Mai, Yiu-Wing

2017-11-15

The polymer solution concentration determines whether electrospinning or electro-spraying occurs, while the addition of the non-solvent into the polymer solution strongly influences the surface morphology of the obtained products. Both smooth and porous surfaces of the electro-sprayed microspheres can be harvested by choosing different non-solvent and its amount as well as incorporating polymeric additives. The influences of the solution concentration, weight ratio between the non-solvent and the copolymer, and the polymeric additives on the surface morphology and the wettability of the electro-sprayed products were systematically studied. Surface pores and/or asperities on the microsphere surface were mainly caused by the non-solvent induced phase separation (NIPS) and subsequent evaporation of the non-solvent during electro-spraying. With increasing polymer solution concentration, the microsphere was gradually changed to the bead-on-string geometry and finally to a nanofiber form, leading to a sustained decrease of the contact angle (CA). It was found that the substrate coatings derived from the microspheres possessing hierarchical surface pores or dense asperities had high surface roughness and super-hydrophobicity with CAs larger than 150° while sliding angles smaller than 10°; but coatings composed of microspheres with smooth surfaces gave relatively low CAs. Copyright © 2017 Elsevier Inc. All rights reserved.

Aging effect of AlF3 coatings for 193 nm lithography

NASA Astrophysics Data System (ADS)

Zhao, Jia; Wang, Lin; Zhang, Weili; Yi, Kui; Shao, Jianda

2018-02-01

As important part of components for 193 nm lithography, AlF3 coatings deposited by resistive heating method acquire advantages like lower optical loss and higher laser damage threshold, but they also possess some disadvantages like worse stability, which is what aging effect focuses on. AlF3 single-layer coatings were deposited; optical property, surface morphology and roughness, and composition were characterized in different periods. Owing to aging effect, refractive index and extinction coefficient increased; larger and larger roughness caused more and more scattering loss, which was in the same order with absorption at 193.4 nm and part of optical loss; from composition analysis, proportional substitution of AlF3 by alumina may account for changes in refractive index as well as absorption.

Experimental investigation of various surface integrity aspects in hard turning of AISI 4340 alloy steel with coated and uncoated cermet

NASA Astrophysics Data System (ADS)

Das, Anshuman; Patel, S. K.; Sateesh Kumar, Ch.; Biswal, B. B.

2018-03-01

The newer technological developments are exerting immense pressure on domain of production. These fabrication industries are busy finding solutions to reduce the costs of cutting materials, enhance the machined parts quality and testing different materials, which can be made versatile for cutting materials, which are difficult for machining. High-speed machining has been the domain of paramount importance for mechanical engineering. In this study, the variation of surface integrity parameters of hardened AISI 4340 alloy steel was analyzed. The surface integrity parameters like surface roughness, micro hardness, machined surface morphology and white layer of hardened AISI 4340 alloy steel were compared using coated and uncoated cermet inserts under dry cutting condition. From the results, it was deduced that coated insert outperformed uncoated one in terms of different surface integrity characteristics.

Osteoblastlike cell adhesion on titanium surfaces modified by plasma nitriding.

PubMed

da Silva, Jose Sandro Pereira; Amico, Sandro Campos; Rodrigues, Almir Olegario Neves; Barboza, Carlos Augusto Galvao; Alves, Clodomiro; Croci, Alberto Tesconi

2011-01-01

The aim of this study was to evaluate the characteristics of various titanium surfaces modified by cold plasma nitriding in terms of adhesion and proliferation of rat osteoblastlike cells. Samples of grade 2 titanium were subjected to three different surface modification processes: polishing, nitriding by plasma direct current, and nitriding by cathodic cage discharge. To evaluate the effect of the surface treatment on the cellular response, the adhesion and proliferation of osteoblastlike cells (MC3T3) were quantified and the results were analyzed by Kruskal-Wallis and Friedman statistical tests. Cellular morphology was observed by scanning electron microscopy. There was more MC3T3 cell attachment on the rougher surfaces produced by cathodic cage discharge compared with polished samples (P < .05). Plasma nitriding improves titanium surface roughness and wettability, leading to osteoblastlike cell adhesion.

Landscape Evolution and the Reincarnation of the Residual CO2 Ice Cap of Mars

NASA Astrophysics Data System (ADS)

Byrne, S.; Zuber, M.

2006-12-01

Observations of the southern residual CO2 cap of Mars reveal a wide range of landforms including flat-floored quasi-circular pits with steep walls (dubbed Swiss-cheese features). Interannual comparisons show that these depressions are expanding laterally at rates of ~2m/yr to ~4m/yr, prompting suggestions of climate change. The residual CO2 ice cap is up to 10m thick and underlain by an involatile basement, it also contains layers roughly 2m thick representing different accumulation episodes in the recent past. Changes in the appearance of the residual ice between the Mariner 9 and Viking missions indicate that the top-most layer was deposited in that time-frame, soon after the global dust storm of 1971. The spatial density of the Swiss-cheese features, and the rate at which they expand, mean that it is unlikely that any part of the residual ice cap is older than a few centuries. Given this, we may ask: how can there be a residual cap present today for us to observe? To answer this and other questions we have developed a model to examine the evolution of a CO2 ice landscape. This model reproduces the morphologies and expansion rates seen in the actual residual CO2 ice cap. Our model results indicate that the fate of CO2 ice surfaces is controlled by their surface roughness. Surface roughness always increases with time, which results in an unstable situation. When the surface roughness exceeds a critical point small pits can begin to develop. The walls of these pits rapidly steepen and begin retreating which enlarges and deepens the pit. This situation always occurs even if the surface of the CO2 slab has a high enough albedo to have a net mass gain each year. Once these pits begin expanding they quickly erode the entire ice slab. When the underlying non-CO2 material is exposed, it will not frost over again if Mars were to repeat like clockwork every year. We conclude that interannual climatic variability is actually a requirement for the continued existence of a residual CO2 ice cap. We invoke unusual depositional episodes (which have a surface smoothing effect) after which the cap can begin accumulating mass and growing in thickness again. This continues until the surface roughness again exceeds a stable state and the process repeats itself. The thickness of the residual cap therefore oscillates on timescales of centuries. The total cap volume may also be affected by variations in residual cap extent. The cap is not 'stable' in the usual sense of the word, but instead is constantly being destroyed and recreated. Evidence suggests that these rejuvenating depositional events are linked to global dust storms. The 10m thick stratigraphic record thus provides a unique measure of interannual variability of the current climate, the expanding Swiss-cheese features do not indicate secular climate change, but instead are just part of the larger life-cycle of this ice deposit. We will report on this surface modeling which reproduces other morphologies within the residual cap and present a historical model based on combining our modeling with the feature sizes and ablation rates found within the present residual ice cap.

Evaluation of biocidal efficacy of copper alloy coatings in comparison with solid metal surfaces: generation of organic copper phosphate nanoflowers.

PubMed

Gutierrez, H; Portman, T; Pershin, V; Ringuette, M

2013-03-01

To analyse the biocidal efficacy of thermal sprayed copper surfaces. Copper alloy sheet metals containing >60% copper have been shown to exhibit potent biocidal activity. Surface biocidal activity was assessed by epifluorescence microscopy. After 2-h exposure at 20 °C in phosphate-buffered saline (PBS), contact killing of Gram-negative Escherichia coli and Gram-positive Staphylococcus epidermidis by brass sheet metal and phosphor bronze was 3-4-times higher than that by stainless steel. SEM observations revealed that the surface membranes of both bacterial strains were slightly more irregular when exposed to brass sheet metal than stainless steel. However, when exposed to phosphor bronze coating, E. coli were 3-4 times larger with irregular membrane morphology. In addition, the majority of the cells were associated with spherical carbon-copper-phosphate crystalline nanostructures characteristic of nanoflowers. The membranes of many of the S. epidermidis exhibited blebbing, and a small subset was also associated with nanoflowers. Our data indicate that increasing the surface roughness of copper alloys had a pronounced impact on the membrane integrity of Gram-positive and, to a lesser degree, Gram-negative bacteria. In the presence of PBS, carbon-copper-phosphate-containing nanoflowers were formed, likely nucleated by components derived from killed bacteria. The intimate association of the bacteria with the nanoflowers and phosphor bronze coating likely contributed to their nonreversible adhesion. Thermal spraying of copper alloys provides a strategy for the rapid coating of three-dimensional organic and inorganic surfaces with biocidal copper alloys. Our study demonstrates that the macroscale surface roughness generated by the thermal spray process enhances the biocidal activity of copper alloys compared with the nanoscale surface roughness of copper sheet metals. Moreover, the coating surface topography provides conditions for the rapid formation of organic copper phosphate nanocrystals/nanoflowers. © 2012 The Society for Applied Microbiology.

Surface roughness measurement in the submicrometer range using laser scattering

NASA Astrophysics Data System (ADS)

Wang, S. H.; Quan, Chenggen; Tay, C. J.; Shang, H. M.

2000-06-01

A technique for measuring surface roughness in the submicrometer range is developed. The principle of the method is based on laser scattering from a rough surface. A telecentric optical setup that uses a laser diode as a light source is used to record the light field scattered from the surface of a rough object. The light intensity distribution of the scattered band, which is correlated to the surface roughness, is recorded by a linear photodiode array and analyzed using a single-chip microcomputer. Several sets of test surfaces prepared by different machining processes are measured and a method for the evaluation of surface roughness is proposed.

Influence of Roughness-Induced Slip on Colloid Transport: Experimental and Modelling Insights

NASA Astrophysics Data System (ADS)

Rasmuson, J. A.; Johnson, W. P.

2017-12-01

A limitation of classic colloid filtration theory is that it applies only to smooth surfaces, yet most natural surfaces present some degree of nano- to micro-scale roughness. A large volume of research has been dedicated to understanding the effects of roughness on particle attachment at the nano-scale since these interactions dictate field scale transport behavior. It has been previously demonstrated that roughness imposes a finite slip vector at the surface that causes particles to experience higher near-surface velocities than would be expected over a smooth surface. Slip near a rough surface can affect two primary mechanisms of particle attenuation: 1) interception of the surface (finding a landing spot) and 2) arrest on the surface (sticking the landing). However, a clear designation on how slip affects particle transport near rough surfaces is missing. The goal of this study was to provide a guide for the height of the slip layer and contact surface in reference to the mean-plane for rough surfaces. Direct observation was used to measure near-surface velocities of particles translating near surfaces of varying roughness spanning three orders of magnitude. The influence of roughness on particle transport was investigated using computational fluid dynamics (CFD) modeling with rough surfaces measured with atomic force microscopy (AFM). The CFD and experimental results were used to calibrate a Lagrangian particle transport model that utilizes simple modifications to the flow field for a smooth surface using statistically based roughness parameters. Advantages of the Lagrangian model are significantly decreased computation times and applicability to a wide range of natural surfaces without explicitly simulating individual asperities. The results suggest that the no-slip boundary should be placed at the bottom of the maximum asperity valleys, and that the contact surface should be placed at the root mean square (RMS) roughness above the mean plane. Collector surfaces with the greatest RMS roughness had the highest sensitivity to the placement of the contact surface. These findings highlight the need for accurate and representative AFM measurements and have important implications for future transport models.

Influence of shot peening on surface quality of austenitic and duplex stainless steel

NASA Astrophysics Data System (ADS)

Vinoth Jebaraj, A.; Sampath Kumar, T.; Ajay Kumar, L.; Deepak, C. R.

2017-11-01

In the present investigation, an attempt has been made to enhance the surface quality of austenitic stainless steel 316L and duplex stainless steel 2205 through shot peening process. The study mainly focuses the surface morphology, microstructural changes, surface roughness and microhardness of the peened layers. Metallography analysis was carried out and compared with the unpeened surface characteristics. As result of peening process, surface recrystallization was achieved on the layers of the peened samples. It was found that shot peening plays significant role in enhancing the surface properties of 316L and 2205. Particularly it has greater influence on the work hardening of austenitic stainless steel than the duplex stainless steel due to its more ductility nature under the investigated shot peening parameters. The findings of the present study will be useful with regard to the enhancement of surface texture achieved through peening.

Surface modification of polylactic acid films by atmospheric pressure plasma treatment

NASA Astrophysics Data System (ADS)

Kudryavtseva, V. L.; Zhuravlev, M. V.; Tverdokhlebov, S. I.

2017-09-01

A new approach for the modification of polylactic acid (PLA) materials using atmospheric pressure plasma (APP) is described. PLA films plasma exposure time was 20, 60, 120 s. The surface morphology and wettability of the obtained PLA films were investigated by atomic force microscopy (AFM) and the sitting drop method. The atmospheric pressure plasma increased the roughness and surface energy of PLA film. The wettability of PLA has been improved with the application of an atmospheric plasma surface treatment. It was shown that it is possible to obtain PLA films with various surface relief and tunable wettability. Additionally, we demonstrated that the use of cold atmospheric pressure plasma for surface activation allows for the immobilization of bioactive compounds like hyaluronic acid (HA) on the surface of obtained films. It was shown that composite PLA-HA films have an increased long-term hydrophilicity of the films surface.

Modification of polycarbonate surface in oxidizing plasma

NASA Astrophysics Data System (ADS)

Ovtsyn, A. A.; Smirnov, S. A.; Shikova, T. G.; Kholodkov, I. V.

2017-11-01

The properties of the surface of the film polycarbonate Lexan 8010 were experimentally studied after treatment in a DC discharge plasma in oxygen and air at pressures of 50-300 Pa and a discharge current of 80 mA. The contact angles of wetting and surface energies are measured. The topography of the surface was investigated by atomic force microscopy. The chemical composition of the surface was determined from the FT-IR spectroscopy data in the variant of total internal reflection, as well as X-ray photoelectron spectroscopy. Treatment in the oxidizing plasma leads to a change in morphology (average roughness increases), an increase in the surface energy, and the concentration of oxygen-containing groups (hydroxyl groups, carbonyl groups in ketones or aldehydes and in oxyketones) on the surface of the polymer. Possible reasons for the difference in surface properties of polymer under the action of oxygen and air plasma on it are discussed.

Understanding EUV mask blank surface roughness induced LWR and associated roughness requirement

NASA Astrophysics Data System (ADS)

Yan, Pei-Yang; Zhang, Guojing; Gullikson, Eric M.; Goldberg, Ken A.; Benk, Markus P.

2015-03-01

Extreme ultraviolet lithography (EUVL) mask multi-layer (ML) blank surface roughness specification historically comes from blank defect inspection tool requirement. Later, new concerns on ML surface roughness induced wafer pattern line width roughness (LWR) arise. In this paper, we have studied wafer level pattern LWR as a function of EUVL mask surface roughness via High-NA Actinic Reticle Review Tool. We found that the blank surface roughness induced LWR at current blank roughness level is in the order of 0.5nm 3σ for NA=0.42 at the best focus. At defocus of ±40nm, the corresponding LWR will be 0.2nm higher. Further reducing EUVL mask blank surface roughness will increase the blank cost with limited benefit in improving the pattern LWR, provided that the intrinsic resist LWR is in the order of 1nm and above.

Research of Surface Roughness Anisotropy

NASA Astrophysics Data System (ADS)

Bulaha, N.; Rudzitis, J.; Lungevics, J.; Linins, O.; Krizbergs, J.

2017-04-01

The authors of the paper have investigated surfaces with irregular roughness for the purpose of determination of roughness spacing parameters perpendicularly to machining traces - RSm1 and parallel to them - RSm2, as well as checking the relationship between the surface anisotropy coefficient c and surface aspect ratio Str from the standard LVS EN ISO 25178-2. Surface roughness measurement experiments with 11 surfaces show that measuring equipment values of mean spacing of profile irregularities in the longitudinal direction are not reliable due to the divergence of surface mean plane and roughness profile mean line. After the additional calculations it was stated that parameter Str can be used for determination of parameter RSm2 and roughness anisotropy evaluation for grinded, polished, friction surfaces and other surfaces with similar characteristics.

Smoothed particle hydrodynamics study of the roughness effect on contact angle and droplet flow.

PubMed

Shigorina, Elena; Kordilla, Jannes; Tartakovsky, Alexandre M

2017-09-01

We employ a pairwise force smoothed particle hydrodynamics (PF-SPH) model to simulate sessile and transient droplets on rough hydrophobic and hydrophilic surfaces. PF-SPH allows modeling of free-surface flows without discretizing the air phase, which is achieved by imposing the surface tension and dynamic contact angles with pairwise interaction forces. We use the PF-SPH model to study the effect of surface roughness and microscopic contact angle on the effective contact angle and droplet dynamics. In the first part of this work, we investigate static contact angles of sessile droplets on different types of rough surfaces. We find that the effective static contact angles of Cassie and Wenzel droplets on a rough surface are greater than the corresponding microscale static contact angles. As a result, microscale hydrophobic rough surfaces also show effective hydrophobic behavior. On the other hand, microscale hydrophilic surfaces may be macroscopically hydrophilic or hydrophobic, depending on the type of roughness. We study the dependence of the transition between Cassie and Wenzel states on roughness and droplet size, which can be linked to the critical pressure for the given fluid-substrate combination. We observe good agreement between simulations and theoretical predictions. Finally, we study the impact of the roughness orientation (i.e., an anisotropic roughness) and surface inclination on droplet flow velocities. Simulations show that droplet flow velocities are lower if the surface roughness is oriented perpendicular to the flow direction. If the predominant elements of surface roughness are in alignment with the flow direction, the flow velocities increase compared to smooth surfaces, which can be attributed to the decrease in fluid-solid contact area similar to the lotus effect. We demonstrate that classical linear scaling relationships between Bond and capillary numbers for droplet flow on flat surfaces also hold for flow on rough surfaces.