Comparative study of etched enamel and dentin for the adhesion of composite resins with the Er:YAG 2,94 μm laser and CO2 9,6 μm laser: morphological (SEM) and tensile bond strength analysis

International Nuclear Information System (INIS)

Marraccini, Tarso Mugnai

2002-01-01

The aim of this study was to evaluate and compare the tensile bond strength of a composite resin adhered to the enamel and dentin which have received superficial irradiation with an Er:YAG laser (2.94 μm) or with CO 2 laser ( 9.6 μm) and later on etched with the phosphoric acid at 35%. After the use of the adhesive system, resin cones were made on the etched surfaces by both lasers and tensile bond strength tests were performed. All samples were observed at the SEM - there was an increase of the degree of fusion and resolidification in the irradiated enamel and dentin samples with the CO 2 laser (9.6 μm), creating a vitrified layer with tiny craters. With the Er:YAG laser (2.94 μm) there were typical morphological explosive microablation with the exposition of the tubules in the dentin.The surface acquired by the association of the CO 2 laser ( 9.6 μm) plus acid etching no longer presented the aspect of fusion being this layer completely removed. There were statistical significant differences among ali three methods of etching in the treatment of the enamel and dentin surface. The tensile bond strength test showed that etching of these enamel and dentin surfaces with acid exclusively (control group) presented great values, surpassing the values of the etching acquired with the Er:YAG laser (2.94 μ) plus acid or the CO 2 laser (9.6 μm) plus acid. With the parameters used in this experiment the Er:YAG laser (2.94 μm) showed to be more effective than the CO 2 laser (9.6 μm) for the hard dental surfaces etching procedure. (author)

Morphology of the adult male and pupal exuviae of Glyptotendipes (Glyptotendipes) glaucus (Meigen 1818) (Diptera, Chironomidae) using scanning electron microscope (SEM).

Science.gov (United States)

Kownacki, Andrzej; Woznicka, Olga; Szarek-Gwiazda, Ewa; Michailova, Paraskeva; Czaplicka, Anna

2017-02-27

In this paper, a study of the morphology of the pupa and male imago of Glyptotendipes (G.) glaucus (Meigen 1818) was carried out, with the aid of a scanning electron microscope (SEM). The SEM provided additional valuable information on the morphology of the species. Adult male head, antenna, wing, leg, abdomen, hypopygium, pupal cephalothorax and abdomen were examined. It is emphasized that SEM was not often used in Chironomidae studies. The present results confirm SEM as a suitable approach in carrying out morphological and taxonomical descriptions of Chironomidae species.

The importance of scanning electron microscopy (sem in taxonomy and morphology of Chironomidae (Diptera

Directory of Open Access Journals (Sweden)

Andrzej Kownacki

2015-07-01

Full Text Available The paper reports on the value of scanning electron microscopy (SEM in the taxonomy and morphology of Chironomidae. This method has been relatively rarely used in Chironomidae studies. Our studies suggest that the SEM method provides a lot of new information. For example, the plastron plate of the thoracic horn of Macropelopia nebulosa (Meigen under light microscopy is visible as points, while under SEM we have found that it consists of a reticular structure with holes. By using SEM a more precise picture of the body structure of Chironomidae can be revealed. It allows researchers to explain inconsistencies in the existing descriptions of species. Another advantage of the SEM method is obtaining spatial images of the body and organs of Chironomidae. However, the SEM method also has some limitations. The main problem is dirt or debris (e.g. algae, mud, secretions, mucus, bacteria, etc., which often settles on the external surface of structures, especially those which are uneven or covered with hair. The dirt should be removed after collection of chironomid material because if left in place it can become chemically fixed to various surfaces. It unnecessarily remains at the surface and final microscopic images may contain artifacts that obscure chironomid structures being investigated. In this way many details of the surface are thus unreadable. The results reported here indicate that SEM examination helps us to identify new morphological features and details that will facilitate the identification of species of Chironomidae and may help to clarify the function of various parts of the body. Fast development of electron microscope technique allows us to learn more about structure of different organisms.

Morphology, structure, aggregates of the particulates as generated by the ablation process

International Nuclear Information System (INIS)

Ghaly, W.A.

2011-01-01

The morphology of the particulates. Aggregates and surface structures which generated by plasma ablation is investigated. Also the morphology terms for the particles, agglomerates, laser depths on solid surfaces which generated by nanosecond laser ablation are demonstrated.The morphology terms in the present work are described according to the visual appearance of micrographs which taken by the scanning electron microscope (SEM). The terms describe what the SEM image looks like but not necessarily what it actually might be or what the material type is . A suggested scientific method to describe the shape, morphology and structure of particulates which apply a surface plot of digital imaging processing (DIP) technique is introduced. The aim of the present work is to develop and extend the data -base of the particle morphology glossary of SEM for the central laboratory of elemental and isotopic analysis at Egyptian Atomic Energy Authority.

Filler segmentation of SEM paper images based on mathematical morphology.

Science.gov (United States)

Ait Kbir, M; Benslimane, Rachid; Princi, Elisabetta; Vicini, Silvia; Pedemonte, Enrico

2007-07-01

Recent developments in microscopy and image processing have made digital measurements on high-resolution images of fibrous materials possible. This helps to gain a better understanding of the structure and other properties of the material at micro level. In this paper SEM image segmentation based on mathematical morphology is proposed. In fact, paper models images (Whatman, Murillo, Watercolor, Newsprint paper) selected in the context of the Euro Mediterranean PaperTech Project have different distributions of fibers and fillers, caused by the presence of SiAl and CaCO3 particles. It is a microscopy challenge to make filler particles in the sheet distinguishable from the other components of the paper surface. This objectif is reached here by using switable strutural elements and mathematical morphology operators.

Optimization study of direct morphology observation by cold field emission SEM without gold coating.

Science.gov (United States)

He, Dan; Fu, Cheng; Xue, Zhigang

2018-06-01

Gold coating is a general operation that is generally applied on non-conductive or low conductive materials, during which the morphology of the materials can be examined by scanning electron microscopy (SEM). However, fatal deficiencies in the materials can result in irreversible distortion and damage. The present study directly characterized different low conductive materials such as hydroxyapatite, modified poly(vinylidene fluoride) (PVDF) fiber, and zinc oxide nanopillar by cold field emission scanning electron microscopy (FE-SEM) without a gold coating. According to the characteristics of the low conductive materials, various test conditions, such as different working signal modes, accelerating voltages, electron beam spots, and working distances, were characterized to determine the best morphological observations of each sample. Copyright © 2018 Elsevier Ltd. All rights reserved.

Structural, morphological and optical properties of pulsed laser deposited ZnSe/ZnSeO3 thin films

Science.gov (United States)

Hassan, Syed Ali; Bashir, Shazia; Zehra, Khushboo; Salman Ahmed, Qazi

2018-04-01

The effect of varying laser pulses on structural, morphological and optical behavior of Pulsed Laser Deposited (PLD) ZnSe/ZnSeO3 thin films has been investigated. The films were grown by employing Excimer laser (100 mJ, 248 nm, 18 ns, 30 Hz) at various number of laser pulses i.e. 3000, 4000, 5000 and 6000 with elevated substrate temperature of 300 °C. One film was grown at Room Temperature (RT) by employing 3000 number of laser pulses. In order to investigate the structural analysis of deposited films, XRD analysis was performed. It was observed that the room temperature is not favorable for the growth of crystalline film. However, elevated substrate temperature to 300°C, two phases with preferred orientation of ZnSeO3 (2 1 2) and ZnSe (3 3 1) were identified. AFM and SEM analysis were performed to explore the surface morphology of grown films. Morphological analysis also confirmed the non-uniform film growth at room temperature. At elevated substrate temperature (300 °C), the growth of dendritic rods and cubical crystalline structures are observed for lower number of laser pulses i.e. 3000 and 4000 respectively. With increased number of pulses i.e. 5000 and 6000, the films surface morphology becomes smooth which is confirmed by measurement of surface RMS roughness. Number of grains, skewness, kurtosis and other parameters have been evaluated by statistical analysis. In order to investigate the thickness, and optical properties of deposited films, ellipsometery and UV–Vis spectroscopy techniques were employed. The estimated band gap energy is 2.67 eV for the film grown at RT, whereas band gap values varies from 2.80 eV to 3.01 eV for the films grown at 300 °C with increasing number of laser pulses.

Cryogenic-SEM investigation of CO{sub 2} hydrate morphologies

Energy Technology Data Exchange (ETDEWEB)

Camps, A.P.; Milodowski, A.; Rochelle, C.; Williams, J.F.; Jackson, P. D. [British Geological Survey, Keyworth, Nottinghamshire (United Kingdom); Camps, A.P; Lovell, M.; Williams, J.F. [Leicester Univ., Leicester (United Kingdom). Dept. of Geology

2008-07-01

Gas hydrates occur naturally around the world in the shallow-marine geosphere, and are seen as a drilling hazard in the petroleum industry due to their role in the carbon cycle, and their possible contribution in past and present climate change. Hydrates are ice-like structures composed of cages of water molecules containing one or more guest molecules, such as methane and carbon dioxide (CO{sub 2}). CO{sub 2} hydrates also occur naturally on earth and are being investigated for their potential to store large volumes of CO{sub 2} to reduce atmospheric emissions of greenhouse gases as a climate change mitigation strategy. However, the mineralogy and formation processes of hydrates are relatively poorly understood. Different imaging techniques have been utilized to study gas hydrates, such as nuclear magnetic resonance, magnetic resonance imaging, and x-ray computed tomography. Scanning Electron Microscopy (SEM) at cryogenic temperatures is another technique to study hydrates, and has been used successfully for investigation of methane and CO{sub 2} hydrates. This paper presented a study that investigated CO{sub 2} hydrates formed in laboratories, using a cryogenic-SEM. The paper presented the study methods and observations, including euhedral crystalline carbon dioxide hydrate; acicular carbon dioxide hydrate; granoblastic carbon dioxide hydrate; and gas rich carbon dioxide hydrate. It was concluded that the investigation produced various different hydrate morphologies resulting from different formation conditions. Morphologies ranged from well-defined euhedral crystals to acicular needles, and more complex, intricate forms. 22 refs., 6 figs., 1 appendix.

Morphological evaluation of cavity preparation surface after duraphat and Er:YAG laser treatment by scanning electronic microscopy

International Nuclear Information System (INIS)

Rodrigues, Luciane Borelli

2002-01-01

The treatment of dental surface using different lasers to prevent dental caries has been studied for several on last years. The purpose of this in vitro study was to evaluate the morphological changes on dentin surface from pulpal wall of cavity preparations performed by high-speed drill, treated with 2,26% fluoride varnish (Duraphat) and Er:YAG laser, and then submitted after receiving or not to EDTA 15% treatment. Twenty Class V cavities were performed on ten humans molars. The specimens were randomly divided in to 4 groups: group 1- treatment with Duraphat followed by Er:YAG laser irradiation (120 mJ/ 4 Hz); group 2: Er:YAG laser irradiation, same parameters, followed by Duraphat treatment; group 3- same group 1 followed by immersion in EDTA (5 min); group 4 - same as group 2 followed by immersion in EDTA (5 min). The specimens were processed for SEM analysis. The micrographs showed that Duraphat treatment promoted morphological changes on dentin, closing dentinal tubules; the specimens treated by Duraphat and Er:YAG laser and immersed in EDTA (group 3) showed homogeneous surface, closed and protected dentinal tubules, maintenance of the fluoride varnish on the dentin surface and around the dentinal tubules, showing feasible and efficiency of these therapies the feasibility.(author)

Morphology of the European species of the aphid genus Eulachnus (Hemiptera: Aphididae: Lachninae) - A SEM comparative and integrative study.

Science.gov (United States)

Kanturski, Mariusz; Karcz, Jagna; Wieczorek, Karina

2015-09-01

Scanning electron microscopy (SEM) methods were used for the first time to elucidate the external morphology of the European species of the genus Eulachnus (Hemiptera: Aphididae: Lachninae), a representative genus of the conifer-feeding aphids tribe Eulachnini. We examined and compared the external morphology of apterous and alate viviparous females from the parthenogenetic generation as well as oviparous females and alate males belonging to the sexual generation. FE-SEM images based on HMDS and cryo-SEM preparation techniques revealed better image quality than the CPD technique in regard to surface tension and morphological signs of cell deteriorations (i.e., existence of depressions, drying artifacts and membrane blebs). Three morphologically different species groups "agilis", "brevipilosus" and "cembrae" were proposed due to the differences in head, antennae, legs and dorsal chaetotaxy as well as dorsal sclerotization. The most characteristic features and differences of representatives of these groups are presented and discussed. Copyright © 2015 Elsevier Ltd. All rights reserved.

Study of Morphological Changes of The Lime Putties During Maturing by SEM/ESEM

Czech Academy of Sciences Publication Activity Database

Navrátilová, Eva; Neděla, Vilém

2017-01-01

Roč. 23, S1 (2017), s. 2186-2187 ISSN 1431-9276 R&D Projects: GA MŠk ED0017/01/01 Institutional support: RVO:68081731 Keywords : SEM * ESEM * morphological changes * lime putties Subject RIV: JA - Electronics ; Optoelectronics, Electrical Engineering OBOR OECD: Civil engineering Impact factor: 1.891, year: 2016

Morphology, thermoelectric properties and wet-chemical doping of laser-sintered germanium nanoparticles

International Nuclear Information System (INIS)

Stoib, Benedikt; Langmann, Tim; Matich, Sonja; Sachsenhauser, Matthias; Stutzmann, Martin; Brandt, Martin S.; Petermann, Nils; Wiggers, Hartmut

2013-01-01

Porous, highly doped semiconductors are potential candidates for thermoelectric energy conversion elements. We report on the fabrication of thin films of Ge via short-pulse laser-sintering of Ge nanoparticles (NPs) in vacuum and study the macroporous morphology of the samples by secondary electron microscopy (SEM) imaging. The temperature dependence of the electrical conductivity and the Seebeck coefficient of undoped Ge is discussed in conjunction with the formation of a defect band near the valence band. We further introduce a versatile method of doping the resulting films with a variety of common dopant elements in group-IV semiconductors by using a liquid containing the dopant atoms. This method is fully compatible with laser-direct writing and suited to fabricate small scale thermoelectric generators. The incorporation of the dopants is verified by X-ray photoelectron spectroscopy (XPS) and their electrical activation is studied by conductivity and thermopower measurements. (Copyright copyright 2013 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

Effect of two bleaching agents on enamel morphology: a SEM study

Directory of Open Access Journals (Sweden)

Ghavam M.

2005-05-01

Full Text Available Statement of Problem: Bleaching materials are able to change the surface morphology as well as mineral and organic content of tooth structure. Considering that bleaching is done for aesthetic purpose, awareness of the possible effect of these materials on hard tissue is important, because it may affect the restorative treatments. Purpose: The aim of this study was comparing the effect of two bleaching materials, Kimia and Ultradent both containing 35% H2O2, on tooth enamel by SEM. Materials and Methods: Five intact central incisors were cut into three sections vertically and each part was randomly divided into three groups. Group 1 (control, without any bleaching. Group 2, bleached with Kimia 35% H2O2. Group 3, bleached with Ultradent 35% H2O2. Each tooth served as its own control. Then the samples were observed by SEM with 250 and 500 magnifications. Results: In the control group some scratches and small white grains were observed which seems to be the result of mastication trauma and pumice powder. In the other groups, morphologic changes like increased surface roughness, deepening of cracks, rod exposure and presence of new cracks were observed. The two experimental materials did not differ in these regards. Conclusion: It seems that both studied materials have limited destructive effects on tooth enamel which seems to be of no clinical importance.

Comparison of the external physical damages between laser-assisted and mechanical immobilized human sperm using scanning electronic microscopy.

Directory of Open Access Journals (Sweden)

David Y L Chan

Full Text Available We aim to visualize the external physical damages and distinct external phenotypic effects between mechanical and laser-assisted immobilized human spermatozoa using scanning electronic microscopy (SEM. Human spermatozoa were immobilized mechanically or with laser assistance for SEM examination and the membrane integrities were checked on both types of immobilized spermatozoa. We found evidence of external damages at SEM level on mechanically kinked sperm, but not on laser-assisted immobilized sperm. Although no external damage was found on laser-assist immobilized sperm, there were two distinct types of morphological changes when spermatozoa were stricken by infra-red laser. Coiled tails were immediately formed when Laser pulse was applied to the sperm end piece area, whereas laser applied to the sperm principal piece area resulted in a sharp bend of sperm tails. Sperm immobilized by laser did not exhibit any morphological change if the laser did not hit within the on-screen central target zone or if the laser hit the sperm mid piece or head. Our modified membrane integrity assay revealed that the external membrane of more than half of the laser-assisted immobilized sperm remained intact. In conclusion, mechanical immobilization produced membrane damages whilst laser-assisted immobilization did not result in any external membrane damages besides morphological changes at SEM level.

Observation particle morphology of colloidal system by conventional SEM with an improved specimen preparation technique.

Science.gov (United States)

Xu, Jing; Hou, Zhaosheng; Yuan, Xiaojiao; Guo, Hong

2011-08-01

On the basis of our previous report that polymer emulsion with different viscosity can be investigated by conventional scanning electron microscopy (SEM), we have developed an improved specimen preparation technique for obtaining particle morphology and size of colloidal silver, collagen, glutin, and polymer microspheres. In this study, we expect to provide a means for charactering the three-dimensional surface microstructure of colloidal particles. Dilution of the samples with appropriate volatile solvent like ethanol is effective for SEM specimen preparation. At a proper ratio between sample and ethanol, the colloidal particles are dispersed uniformly in ethanol and then deposited evenly on the substrate. Different drying methods are studied to search a proper drying condition, in which the small molecule solvent is removed without destroying the natural particle morphology. And the effects of ethanol in the specimen preparation process are described by analyzing the physicochemical properties of ethanol. The specimen preparation technique is simple and can be achieved in common laboratory for charactering the particle morphology of colloidal system. Copyright © 2010 Wiley-Liss, Inc.

Pulsed Laser Deposition of Zinc Sulfide Thin Films on Silicon: The influence of substrate orientation and preparation on thin film morphology and texture

OpenAIRE

Heimdal, Carl Philip J

2014-01-01

The effect of orientation and preparation of silicon substrates on the growth morphology and crystalline structure of ZnS thin films deposited by pulsed laser deposition (PLD) has been investigated through scanning electron microscopy (SEM) and grazing incidence x-ray diffraction (GIXRD). ZnS thin films were grown on silicon (100) and (111), on HF-treated and untreated silicon (100) as well as substrates coated with Al, Ge and Au. The ZnS films showed entirely different morphologies for ZnS f...

Nanosecond pulsed laser ablation of Ge investigated by employing photoacoustic deflection technique and SEM analysis

International Nuclear Information System (INIS)

Yaseen, Nazish; Bashir, Shazia; Shabbir, Muhammad Kaif; Jalil, Sohail Abdul; Akram, Mahreen; Hayat, Asma; Mahmood, Khaliq; Haq, Faizan-ul; Ahmad, Riaz; Hussain, Tousif

2016-01-01

Nanosecond pulsed laser ablation phenomena of single crystal Ge (100) has been investigated by employing photoacoustic deflection as well as SEM analysis techniques. Nd: YAG laser (1064 nm, 10 ns, 1–10 Hz) at various laser fluences ranging from 0.2 to 11 J cm"−"2 is employed as pump beam to ablate Ge targets. In order to evaluate in-situe ablation threshold fluence of Ge by photoacoustic deflection technique, Continuous Wave (CW) He–Ne laser (632 nm, power 10 mW) is employed as a probe beam. It travels parallel to the target surface at a distance of 3 mm and after passing through Ge plasma it causes deflection due to density gradient of acoustic waves. The deflected signal is detected by photodiode and is recorded by oscilloscope. The threshold fluence of Ge, the velocity of ablated species and the amplitude of the deflected signal are evaluated. The threshold fluence of Ge comes out to be 0.5 J cm"−"2 and is comparable with the analytical value. In order to compare the estimated value of threshold with ex-situe measurements, the quantitative analysis of laser irradiated Ge is performed by using SEM analysis. For this purpose Ge is exposed to single and multiple shots of 5, 10, 50 and 100 at various laser fluences ranging from 0.2 to 11 J cm"−"2. The threshold fluence for single and multiple shots as well as incubation coefficients are evaluated. It is observed that the value of incubation co-efficient decreases with increasing number of pulses and is therefore responsible for lowering the threshold fluence of Ge. SEM analysis also reveals the growth of various features such as porous structures, non-uniform ripples and blisters on the laser irradiated Ge. It is observed that both the fluence as well as number of laser shots plays a significant role for the growth of these structures.

Nanosecond pulsed laser ablation of Ge investigated by employing photoacoustic deflection technique and SEM analysis

Energy Technology Data Exchange (ETDEWEB)

Yaseen, Nazish; Bashir, Shazia; Shabbir, Muhammad Kaif; Jalil, Sohail Abdul; Akram, Mahreen; Hayat, Asma; Mahmood, Khaliq; Haq, Faizan-ul; Ahmad, Riaz; Hussain, Tousif

2016-06-01

Nanosecond pulsed laser ablation phenomena of single crystal Ge (100) has been investigated by employing photoacoustic deflection as well as SEM analysis techniques. Nd: YAG laser (1064 nm, 10 ns, 1–10 Hz) at various laser fluences ranging from 0.2 to 11 J cm{sup −2} is employed as pump beam to ablate Ge targets. In order to evaluate in-situe ablation threshold fluence of Ge by photoacoustic deflection technique, Continuous Wave (CW) He–Ne laser (632 nm, power 10 mW) is employed as a probe beam. It travels parallel to the target surface at a distance of 3 mm and after passing through Ge plasma it causes deflection due to density gradient of acoustic waves. The deflected signal is detected by photodiode and is recorded by oscilloscope. The threshold fluence of Ge, the velocity of ablated species and the amplitude of the deflected signal are evaluated. The threshold fluence of Ge comes out to be 0.5 J cm{sup −2} and is comparable with the analytical value. In order to compare the estimated value of threshold with ex-situe measurements, the quantitative analysis of laser irradiated Ge is performed by using SEM analysis. For this purpose Ge is exposed to single and multiple shots of 5, 10, 50 and 100 at various laser fluences ranging from 0.2 to 11 J cm{sup −2}. The threshold fluence for single and multiple shots as well as incubation coefficients are evaluated. It is observed that the value of incubation co-efficient decreases with increasing number of pulses and is therefore responsible for lowering the threshold fluence of Ge. SEM analysis also reveals the growth of various features such as porous structures, non-uniform ripples and blisters on the laser irradiated Ge. It is observed that both the fluence as well as number of laser shots plays a significant role for the growth of these structures.

Spatial confinement effects on spectroscopic and morphological studies of nanosecond laser-ablated Zirconium

Science.gov (United States)

Hayat, Asma; Bashir, Shazia; Rafique, Muhammad Shahid; Ahmad, Riaz; Akram, Mahreen; Mahmood, Khaliq; Zaheer, Ali

2017-12-01

Spatial confinement effects on plasma parameters and surface morphology of laser ablated Zr (Zirconium) are studied by introducing a metallic blocker. Nd:YAG laser at various fluencies ranging from 8 J cm-2 to 32 J cm-2 was employed as an irradiation source. All measurements were performed in the presence of Ar under different pressures. Confinement effects offered by metallic blocker are investigated by placing the blocker at different distances of 6 mm, 8 mm and 10 mm from the target surface. It is revealed from LIBS analysis that both plasma parameters i.e. excitation temperature and electron number density increase with increasing laser fluence due to enhancement in energy deposition. It is also observed that spatial confinement offered by metallic blocker is responsible for the enhancement of both electron temperature and electron number density of Zr plasma. This is true for all laser fluences and pressures of Ar. Maximum values of electron temperature and electron number density without blocker are 12,600 K and 14 × 1017 cm-3 respectively whereas, these values are enhanced to 15,000 K and 21 × 1017 cm-3 in the presence of blocker. The physical mechanisms responsible for the enhancement of Zr plasma parameters are plasma compression, confinement and pronounced collisional excitations due to reflection of shock waves. Scanning Electron Microscope (SEM) analysis was performed to explore the surface morphology of laser ablated Zr. It reveals the formation of cones, cavities and ripples. These features become more distinct and well defined in the presence of blocker due to plasma confinement. The optimum combination of blocker distance, fluence and Ar pressure can identify the suitable conditions for defining the role of plasma parameters for surface structuring.

AFM study of the effects of laser surface remelting on the morphology of Al-Fe aerospace alloys

Energy Technology Data Exchange (ETDEWEB)

Pariona, Moises Meza, E-mail: mmpariona@uepg.br [Graduate Program in Engineering and Materials Science, State University of Ponta Grossa (UEPG), Ponta Grossa 84010-919, PR (Brazil); Teleginski, Viviane; Santos, Kelly dos; Leandro Ribeiro dos Santos, Everton; Aparecida de Oliveira Camargo de Lima, Angela [Graduate Program in Engineering and Materials Science, State University of Ponta Grossa (UEPG), Ponta Grossa 84010-919, PR (Brazil); Riva, Rudimar [Department of Aerospace Science and Technology, Institute for Advanced Studies (IEAv), Sao Jose dos Campos 12227-000, SP (Brazil)

2012-12-15

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-ray 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.

Monitoring of Multilayered Bacterial Biofilm Morphology by Cryo-SEM for Raman Spectroscopy Measurements

Czech Academy of Sciences Publication Activity Database

Hrubanová, Kamila; Bernatová, Silvie; Samek, Ota; Šerý, Mojmír; Zemánek, Pavel; Nebesářová, Jana; Růžička, F.; Krzyžánek, Vladislav

2015-01-01

Roč. 21, S3 (2015), s. 187-188 ISSN 1431-9276 R&D Projects: GA MŠk(CZ) LO1212; GA MŠk ED0017/01/01; GA ČR(CZ) GA14-20012S Institutional support: RVO:68081731 ; RVO:60077344 Keywords : multilayered bacterial biofilm * morphology by Cryo-SEM * Raman spectroscopy Subject RIV: JA - Electronics ; Optoelectronics, Electrical Engineering Impact factor: 1.730, year: 2015

Morphology of Poly lactide/Polycaprolactone (PLA/PCL) Nano composite by Scanning Electron Microscopy (SEM)

International Nuclear Information System (INIS)

Siti Zulaiha Hairaldin; Wan Md Zin Wan Yunus; Norazowa Ibrahim

2011-01-01

In this study, Octadecylamine Modified Montmorillonites (ODAMMT) were used to prepare Poly lactide/ Polycaprolactone (PLA/ PCL) nano composites. PLA and PCL mix in 90:10 ratios, using an internal mixer by melt blending technique. The other sample was blend with Natrium Montmorillonite (NaMMT) and Octadecylamine Modified Montmorillonite (ODA-MMT) to produce PLA/ PCL-NaMMT and PLA/ PCL ODAMMT. To characterize the polymer nano composites, X-ray diffraction (XRD), FTIR and SEM analysis were conducted. Comparison of morphology were made up between PLA/ PCL, PLA/ PCL with presence of 7 % of Na-MMT and 7 % ODA-MMT respectively based on SEM micrograph by calculate the number-average diameter. (author)

Using BIB-SEM to determine pore morphology and pore size distributions in coal macerals

Energy Technology Data Exchange (ETDEWEB)

Giffin, S.; Littke, R. [RWTH Aachen Univ. (Germany). Inst. of Geology and Geochemistry of Petroleum and Coal; Klaver, J.; Urai, J.L. [RWTH Aachen Univ. (Germany). Structural Geology, Tectonics and Geomechanics

2013-08-01

The composition of coalbeds is considerably heterogeneous, affecting the transport pathways for fluids within the coal. Transport pathways include cleats and larger pores. However, only a few clues exist as the nature of these pores. This study examines the morphology and distribution of macro- and mesopores in coal samples, using broad ion beam (BIB) milling to prepare relief- and damage-free polished surfaces of coal samples for high-resolution SEM imaging. Broad ion beam milling is advantageous to focused ion beam milling in that a larger surface area can be milled. Combining that with SEM imaging results in a useful tool to study pore morphology and distributions in the size range between 10 nm and 10 {mu}m. Since BIB-sections of a few square millimeters are not large enough to be statistically representative, results cannot be easily interpreted from a coal seam standpoint. Therefore, porosity was investigated as a function of maceral type to characterize pore morphologies. Macerals from the vitrinite and inertinite groups were selected with a known relationship to bedding. BIB-sections were milled parallel to bedding and perpendicular to bedding, and the pores were evaluated in each section. The goal of this study is to (1) qualitatively describe pore morphology with respect to maceral type and (2) quantitatively characterize pore size distributions with respect to maceral and in relationship to bedding. Our results lead to a better understanding of bulk coal porosity due to the visual, spatial representation and quantification of pores in individual macerals. (orig.)

Comparative SEM and LM foliar epidermal and palyno-morphological studies of Amaranthaceae and its taxonomic implications.

Science.gov (United States)

Hussain, Amara Noor; Zafar, Muhammad; Ahmad, Mushtaq; Khan, Raees; Yaseen, Ghulam; Khan, Muhammad Saleem; Nazir, Abdul; Khan, Amir Muhammad; Shaheen, Shabnum

2018-05-01

Palynological features as well as comparative foliar epidermal using light and scanning electron microscope (SEM) of 17 species (10genera) of Amaranthaceae have been studied for its taxonomic significance. Different foliar and palynological micro-morphological characters were examined to explain their value in resolving the difficulty in identification. All species were amphistomatic but stomata on abaxial surface were more abundant. Taxonomically significant epidermal character including stomata type, trichomes (unicellular, multicellular, and capitate) and epidermal cells shapes (polygonal and irregular) were also observed. Pollens of this family are Polypantoporate, pores large, spheroidal, mesoporous region is sparsely to scabrate, densely psilate, and spinulose. All these characters can be active at species level for identification purpose. This study indicates that at different taxonomic levels, LM and SEM pollen and epidermal morphology is explanatory and significant to identify species and genera. © 2018 Wiley Periodicals, Inc.

Fs-laser processing of polydimethylsiloxane

Energy Technology Data Exchange (ETDEWEB)

Atanasov, Petar A., E-mail: paatanas@ie.bas.bg; Nedyalkov, Nikolay N. [Institute of Electronics, Bulgarian Academy of Sciences, 72 Tsarigradsko Shose, Sofia 1784 (Bulgaria); Valova, Eugenia I.; Georgieva, Zhenya S.; Armyanov, Stefan A.; Kolev, Konstantin N. [Rostislaw Kaischew Institute of Physical Chemistry, Bulgarian Academy of Sciences, Acad. G. Bonchev Str., Block 11, Sofia 1113 (Bulgaria); Amoruso, Salvatore; Wang, Xuan; Bruzzese, Ricardo [CNR-SPIN, Dipartimento di Scienze Fisiche, Universita degli Studi di Napoli Federico II, Complesso Universitario di Monte S. Angelo, Via Cintia, I-80126 Napoli (Italy); Sawczak, Miroslaw; Śliwiński, Gerard [Photophysics Department, The Szewalski Institute, Polish Academy of Sciences, 14 Fiszera St, 80-231 Gdańsk (Poland)

2014-07-14

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

Determination of gel content and SEM morphology for sago-PVA blends film

International Nuclear Information System (INIS)

Sarada Idris; Zulkafli Ghazali; Kamarudin Hashim

2006-01-01

Blends of polyvinyl alcohol and sago starch have been prepared to evaluate the potential of producing biodegradable products. Glycerol was introduced in the blends to improve the flexibility of the films as plasticizer in order more flexible film. These blends have been subjected to electron beam irradiation to evaluate and characterized radiation effect on the blends. Subsequently films were produced from this blend. The gel content of un-irradiated and irradiated films as evidence of cross linking was measured and discussed. This paper also discuss the films morphology from Scanning Electron Microscopy(SEM) observation. (Author)

Characterization of Yeast Biofilm by Cryo-SEM and FIB-SEM

Czech Academy of Sciences Publication Activity Database

Hrubanová, Kamila; Nebesářová, Jana; Růžička, F.; Dluhoš, J.; Krzyžánek, Vladislav

2013-01-01

Roč. 19, S2 (2013), s. 226-227 ISSN 1431-9276 R&D Projects: GA MŠk EE.2.3.20.0103; GA TA ČR TE01020118; GA ČR GAP205/11/1687 Institutional support: RVO:68081731 ; RVO:60077344 Keywords : yeast biofilm * cryo-SEM * FIB-SEM Subject RIV: BH - Optics, Masers, Lasers Impact factor: 1.757, year: 2013

Superpulsed low-level laser therapy protects skeletal muscle of mdx mice against damage, inflammation and morphological changes delaying dystrophy progression.

Science.gov (United States)

Leal-Junior, Ernesto Cesar Pinto; de Almeida, Patrícia; Tomazoni, Shaiane Silva; de Carvalho, Paulo de Tarso Camillo; Lopes-Martins, Rodrigo Álvaro Brandão; Frigo, Lucio; Joensen, Jon; Johnson, Mark I; Bjordal, Jan Magnus

2014-01-01

To evaluate the effects of preventive treatment with low-level laser therapy (LLLT) on progression of dystrophy in mdx mice. Ten animals were randomly divided into 2 experimental groups treated with superpulsed LLLT (904 nm, 15 mW, 700 Hz, 1 J) or placebo-LLLT at one point overlying the tibialis anterior muscle (bilaterally) 5 times per week for 14 weeks (from 6th to 20th week of age). Morphological changes, creatine kinase (CK) activity and mRNA gene expression were assessed in animals at 20th week of age. Animals treated with LLLT showed very few morphological changes in skeletal muscle, with less atrophy and fibrosis than animals treated with placebo-LLLT. CK was significantly lower (p=0.0203) in animals treated with LLLT (864.70 U.l-1, SEM 226.10) than placebo (1708.00 U.l-1, SEM 184.60). mRNA gene expression of inflammatory markers was significantly decreased by treatment with LLLT (pmuscle damage and inflammation in mdx mice. This indicates that LLLT has potential to decrease progression of Duchenne muscular dystrophy.

SEM and HRTEM study of porous silicon--relationship between fabrication, morphology and optical properties

International Nuclear Information System (INIS)

Dian, J.; Macek, A.; Niznansky, D.; Nemec, I.; Vrkoslav, V.; Chvojka, T.; Jelinek, I.

2004-01-01

We studied the dependence of porous silicon (PS) morphology on fabrication conditions and the link between morphology, porosity and optical properties. P-type (1 0 0) silicon wafers with resistivity of 10 Ω cm were electrochemically etched in a HF:ethanol:water mixture at various HF concentrations and current densities. Porosity and thickness of the samples were determined gravimetrically. Detailed information about evolution of porous silicon layer morphology with variation of preparation conditions was obtained by scanning electron microscope (SEM), the presence of silicon nanoparticles was confirmed by high resolution transmission electron microscopy. Decrease of the mean size of silicon nanoparticles with increasing porous silicon porosity was revealed in a monotonous blue shift of photoluminescence (PL) maximum in room temperature photoluminescence spectra of studied samples. This blue shift is consistent with quantum confinement model of photoluminescence mechanism. We observed that total porosity of porous films cannot fully explain observed photoluminescence behavior and correct interpretation of the blue shift of photoluminescence spectra requires detailed knowledge of porous silicon morphology

Morphological alterations of radicular dentine pretreated with different irrigating solutions and irradiated with 980-nm diode laser.

Science.gov (United States)

Alfredo, Edson; Souza-Gabriel, Aline E; Silva, Silvio Rocha C; Sousa-Neto, Manoel D; Brugnera-Junior, Aldo; Silva-Sousa, Yara T C

2009-01-01

The topographical features of intraradicular dentine pretreated with sodium hypochlorite (NaOCl) or ethylenediamine tetraacetic acid (EDTA) followed by diode laser irradiation have not yet been determined. To evaluate the alterations of dentine irradiated with 980-nm diode laser at different parameters after the surface treatment with NaOCl and EDTA. Roots of 60 canines were biomechanically prepared and irrigated with NaOCl or EDTA. Groups were divided according to the laser parameters: 1.5 W/CW; 1.5 W/100 Hz; 3.0 W/CW; 3.0 W/100 Hz and no irradiation (control). The roots were splited longitudinally and analyzed by scanning electron microscopy (SEM) in a quali-quatitative way. The scores were submitted to two-way Kruskal-Wallis and Dunn's tests. The statistical analysis demonstrated that the specimens treated only with NaOCl or EDTA (control groups) were statistically different (P laser-irradiated specimens, regardless of the parameter setting. The specimens treated with NaOCl showed a laser-modified surface with smear layer, fissures, and no visible tubules. Those treated with EDTA and irradiated by laser presented absence of smear layer, tubules partially exposed and melting areas. The tested parameters of 980-nm diode laser promoted similar alterations on dentine morphology, dependent to the type of surface pretreatment. Copyright 2008 Wiley-Liss, Inc.

Morphological changes in ultrafast laser ablation plumes with varying spot size.

Science.gov (United States)

Harilal, S S; Diwakar, P K; Polek, M P; Phillips, M C

2015-06-15

We investigated the role of spot size on plume morphology during ultrafast laser ablation of metal targets. Our results show that the spatial features of fs LA plumes are strongly dependent on the focal spot size. Two-dimensional self-emission images showed that the shape of the ultrafast laser ablation plumes changes from spherical to cylindrical with an increasing spot size from 100 to 600 μm. The changes in plume morphology and internal structures are related to ion emission dynamics from the plasma, where broader angular ion distribution and faster ions are noticed for the smallest spot size used. The present results clearly show that the morphological changes in the plume with spot size are independent of laser pulse width.

Investigating biomass burning aerosol morphology using a laser imaging nephelometer

Science.gov (United States)

Manfred, Katherine M.; Washenfelder, Rebecca A.; Wagner, Nicholas L.; Adler, Gabriela; Erdesz, Frank; Womack, Caroline C.; Lamb, Kara D.; Schwarz, Joshua P.; Franchin, Alessandro; Selimovic, Vanessa; Yokelson, Robert J.; Murphy, Daniel M.

2018-02-01

Particle morphology is an important parameter affecting aerosol optical properties that are relevant to climate and air quality, yet it is poorly constrained due to sparse in situ measurements. Biomass burning is a large source of aerosol that generates particles with different morphologies. Quantifying the optical contributions of non-spherical aerosol populations is critical for accurate radiative transfer models, and for correctly interpreting remote sensing data. We deployed a laser imaging nephelometer at the Missoula Fire Sciences Laboratory to sample biomass burning aerosol from controlled fires during the FIREX intensive laboratory study. The laser imaging nephelometer measures the unpolarized scattering phase function of an aerosol ensemble using diode lasers at 375 and 405 nm. Scattered light from the bulk aerosol in the instrument is imaged onto a charge-coupled device (CCD) using a wide-angle field-of-view lens, which allows for measurements at 4-175° scattering angle with ˜ 0.5° angular resolution. Along with a suite of other instruments, the laser imaging nephelometer sampled fresh smoke emissions both directly and after removal of volatile components with a thermodenuder at 250 °C. The total integrated aerosol scattering signal agreed with both a cavity ring-down photoacoustic spectrometer system and a traditional integrating nephelometer within instrumental uncertainties. We compare the measured scattering phase functions at 405 nm to theoretical models for spherical (Mie) and fractal (Rayleigh-Debye-Gans) particle morphologies based on the size distribution reported by an optical particle counter. Results from representative fires demonstrate that particle morphology can vary dramatically for different fuel types. In some cases, the measured phase function cannot be described using Mie theory. This study demonstrates the capabilities of the laser imaging nephelometer instrument to provide realtime, in situ information about dominant particle

Influence of plasma shock wave on the morphology of laser drilling in different environments

Science.gov (United States)

Zhai, Zhaoyang; Wang, Wenjun; Mei, Xuesong; Wang, Kedian; Yang, Huizhu

2017-05-01

Nanosecond pulse laser was used to study nickel-based alloy drilling and compare processing results of microholes in air environment and water environment. Through analysis and comparison, it's found that environmental medium had obvious influence on morphology of laser drilling. High-speed camera was used to shoot plasma morphology during laser drilling process, theoretical formula was used to calculate boundary dimension of plasma and shock wave velocity, and finally parameters were substituted into computational fluid dynamics simulation software to obtain solutions. Obtained analysis results could intuitively explain different morphological features and forming reasons between laser drilling in air environment and water environment in the experiment from angle of plasma shock waves. By comparing simulation results and experimental results, it could help to get an understanding of formation mechanism of microhole morphology, thus providing basis for further improving process optimization of laser drilling quality.

Morphological and spectroscopic characterization of laser-ablated tungsten at various laser irradiances

Energy Technology Data Exchange (ETDEWEB)

Akram, Mahreen; Bashir, Shazia; Hayat, Asma; Mahmood, Khaliq; Dawood, Asadullah [Government College University, Centre for Advanced Studies in Physics, Lahore (Pakistan); Rafique, Muhammad Shahid [University of Engineering and Technology, Department of Physics, Lahore (Pakistan); Bashir, M.F. [COMSATS Institute of Information Technology, Department of Physics, Lahore (Pakistan)

2015-06-15

The variation in surface morphology and plasma parameters of laser irradiated tungsten has been investigated as a function of irradiance. For this purpose, Nd:YAG laser (1064 nm, 10 ns, 10 Hz) is employed. Tungsten targets were exposed to various laser irradiances ranging from 6 to 50 GW/cm{sup 2} under ambient environment of argon at a pressure of 20 Torr. Scanning electron microscope analysis has been performed to analyze the surface modification of irradiated tungsten. It revealed the formation of micro- and nanoscale surface structures. In central ablated area, distinct grains and crack formation are observed, whereas peripheral ablated areas are dominated by cones and pinhole formation. It was observed that at irradiances exceeding a value of 13 GW/cm{sup 2}, the morphological trend of the observed structures has been changed from erosion to melting and re-deposition dominant phase. Ablation efficiency as a function of laser irradiance has also been investigated by measuring the crater depth using surface profilometry analysis. It is found to be maximum at an irradiance of 13 GW/cm{sup 2} and decreases at high laser irradiances. In order to correlate the accumulated effects of plasma parameters with the surface modification, laser-induced breakdown spectroscopy analysis has been performed. The electron temperature and number density of tungsten plasma have been evaluated at various laser irradiances. Initially with the increase of the laser irradiance up to 13 GW/cm{sup 2}, an increasing trend is observed for both plasma parameters due to enhanced energy deposition. Afterward, a decreasing trend is achieved which is attributed to the shielding effect. With further increase in irradiance, a saturation stage comes and insignificant changes are observed in plasma parameters. This saturation is explainable on the basis of the formation of a self-regulating regime near the target surface. Surface modifications of laser irradiated tungsten have been correlated with

Morphological modification of TiC by laser irradiation

International Nuclear Information System (INIS)

Baechli, A.; Blatter, A.

1991-01-01

The technique of laser quenching has been applied to TiC coatings on cemented carbide WC/Co material. In contrast to the original columnar morphology of TiC prepared by chemical vapour deposition, the laser-processed surface is isotropic and flat. With the proper parameters a smooth interface is formed and the TiC is alloyed to the substrate. The chemical composition as well as the beneficial tribological properties can be preserved. (orig.)

Larva of Glyptotendipes (Glyptotendipes) glaucus (Meigen 1818) (Chironomidae, Diptera)-morphology by Scanning Electron Microscope (SEM), karyotype, and biology in laboratory conditions.

Science.gov (United States)

Kownacki, Andrzej; Woznicka, Olga; Szarek-Gwiazda, Ewa; Michailova, Paraskeva

2016-09-21

Larvae belonging to the family Chironomidae are difficult to identify. The aim of the present study was to describe the larval morphology of G. (G.) glaucus with the aid of a Scanning Electron Microscope (SEM), the karyotype and biology based on materials obtained from laboratory culture. Describing the morphology of larvae, special attention was paid to rarely or never described structures like the maxilla (lacinia and maxillary palp), the long plate situated below the ventromental plate, and plate X situated between lacinia and mentum. The use of SEM allowed also to obtain better images of labrum and ventromental plate. Morphological features of this species have been supplemented by karyotype and biology of larvae in laboratory conditions. Under controlled experimental conditions we found non-synchronous development of G. (G.) glaucus larvae hatched from one egg mass reflected in different lengths of larvae and emerged imagoes.

Structure and surface morphology studies of cerium oxide system using XRD and SEM analysis

International Nuclear Information System (INIS)

Ahmad Jais Alimin; Farid Nasir Ani; Wan Azelee Wan Abu Bakar

2000-01-01

Conventional Precious Group Materials (PGM) catalyst systems have been using CeO 2 as an Oxygen Storage Capacity component in the catalyst washcoat. Due to the limitations of the PGM catalyst, researches are now focusing on improving or replacing this conventional system. In a previous work, the potential of a copper-ceria (Cu-Ce) oxide as a catalyst system has been identified. In this paper, the morphology and characterisation of Cu-Ce oxides analysed using XRD and SEM will be described. The Cu-Ce samples were prepared at a fixed ratio under temperatures of 400 o C and 800 o C. XRD diffractograms showed CeO 2 is in a cubic phase at 400 o C and 800 o C. At 800 o C, the CuO particle is visible, presumably has incorporated with the lattice structure of ceria, indicating an absent of solid state condition between copper and ceria. Analysis by SEM revealed significant increase in particle sizes with increasing calcination temperatures. (Author)

Palyno-morphological characteristics of gymnosperm flora of pakistan and its taxonomic implications with LM and SEM methods.

Science.gov (United States)

Khan, Raees; Ul Abidin, Sheikh Zain; Ahmad, Mushtaq; Zafar, Muhammad; Liu, Jie; Amina, Hafiza

2018-01-01

The present study is intended to assess gymnosperms pollen flora of Pakistan using Light Microscope (LM) and Scanning Electron Microscopy (SEM) for its taxonomic significance in identification of gymnosperms. Pollens of 35 gymnosperm species (12 genera and five families) were collected from its various distributional sites of gymnosperms in Pakistan. LM and SEM were used to investigate different palyno-morphological characteristics. Five pollen types (i.e., Inaperturate, Monolete, Monoporate, Vesiculate-bisaccate and Polyplicate) were observed. Six In equatorial view seven types of pollens were observed, in which ten species were sub-angular, nine species were Traingular, six species were Perprolate, three species were Rhomboidal, three species were semi-angular, two species were rectangular and two species were prolate. While five types of pollen were observed in polar view, in which ten species were Spheroidal, nine species were Angular, eight were Interlobate, six species were Circular, two species were Elliptic. Eighteen species has rugulate and 17 species has faveolate ornamentation. Eighteen species has verrucate and 17 have gemmate type sculpturing. The data was analysed through cluster analysis. The study showed that these palyno-morphological features have significance value in classification and identification of gymnosperms. Based on these different palyno-morphological features, a taxonomic key was proposed for the accurate and fast identifications of gymnosperms from Pakistan. © 2017 Wiley Periodicals, Inc.

Surface morphology study of some Cu–Ni reference alloys using laser induced breakdown spectroscopy

Energy Technology Data Exchange (ETDEWEB)

Sheta, S.A. [National Institute of Laser Enhanced Science (NILES), Cairo University, 12613, Giza (Egypt); Di Carlo, G.; Ingo, G.M. [Istituto per lo Studio dei Materiali Nanostrutturati (ISMN-CNR), Area della Ricerca Roma 1 Montelibretti, 00016, Monterotondo Scalo, Rome (Italy); Harith, M.A., E-mail: mharithm@niles.edu.eg [National Institute of Laser Enhanced Science (NILES), Cairo University, 12613, Giza (Egypt)

2016-04-15

In the present work a detailed study of the surface morphology of purposely-prepared Cu–Ni reference alloys has been performed. These alloys have been prepared via tailored casting methods in order to have samples with same chemical composition and different local chemical enrichments of both metals. A micro-LIBS system for surface spatial scanning was set up based on a second harmonic Nd:YAG laser at 532 nm and using a focusing lens of focal length 7 cm to disclose the local chemical composition variation. Surface morphological scanning was performed for some of the binary Cu–Ni reference alloys to differentiate between chemically homogeneous and heterogeneous alloys. LIBS results were compared with the information of the Scanning Electron Microscope coupled with Energy Dispersive X-ray (SEMEDS) investigation carried out to provide surface local large-area chemical analysis via EDS technique. It has been proved that LIBS is a simple, sensitive and direct technique in the determination of homogeneity or heterogeneity of the sample's surface. The LIBS results have been shown to be more sensitive and accurate in the heterogeneity determination than other used conventional analytical techniques. - Highlights: • Surface LIBS scanning was performed for Cu–Ni reference alloy samples. • LIBS system was based on a 2nd harmonic Nd:YAG laser and a focusing lens (f = 7 cm). • LIBS results were compared with SEM imaging and EDS chemical analysis. • Surface homogeneity and heterogeneity have been differentiated successfully. • LIBS is a sensitive analytical tool in surface metallurgical study.

Uncertainty in the use of MAMA software to measure particle morphological parameters from SEM images

Energy Technology Data Exchange (ETDEWEB)

Schwartz, Daniel S. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Tandon, Lav [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

2017-06-05

The MAMA software package developed at LANL is designed to make morphological measurements on a wide variety of digital images of objects. At LANL, we have focused on using MAMA to measure scanning electron microscope (SEM) images of particles, as this is a critical part of our forensic analysis of interdicted radiologic materials. In order to successfully use MAMA to make such measurements, we must understand the level of uncertainty involved in the process, so that we can rigorously support our quantitative conclusions.

Morphology of magnetic fields generated in laser-produced plasmas

International Nuclear Information System (INIS)

Boyd, T.J.M.; Cooke, D.

1988-01-01

Magnetic fields in the megagauss range have been measured in experiments on plasmas generated by irradiating targets with high power lasers. A study of the morphology of these self-generated fields is important not only for its intrinsic interest but for possible implications in laser--target physics. In this paper work on the numerical modeling of large magnetic fields generated in target experiments is reported. The results show generally satisfactory agreement with the fields measured experimentally both in terms of the magnitude of the peak fields and their morphology. In the numerical model the contribution from the Hall term in describing the evolution of the magnetic field is shown to be important especially in short pulse (≅100 psec) experiments

Effects of isothermal heat treatment on nanostructured bainite morphology and microstructures in laser cladded coatings

International Nuclear Information System (INIS)

Guo, Yanbing; Feng, Kai; Lu, Fenggui; Zhang, Ke; Li, Zhuguo; Hosseini, Seyed Reza Elmi; Wang, Min

2015-01-01

Highlights: • Nanobainitic coatings under 200, 250 and 300 °C heat treatments are fabricated. • The size of bainite sheaves increased with the isothermal temperature increasing. • Textured and chaotic distributions are observed in 200 and 300 °C microstructures. • The evolution model of nanobainite morphology is established and analyzed. • The bainitic ferrite of 200 °C heat treatment has a true thickness of 45 nm. - Abstract: Laser cladding and subsequent isothermal heat treatments have been used to fabricate nanostructured bainitic coatings. XRD has been used to determine the kinetics of bainitic transformation process. OM, SEM and TEM have been used to characterize the morphology and microstructures at different stages of transformation. The results showed that at the initial stage of bainitic transformation, the bainite sheaves are short and thin at a relatively low transformation temperature. The fully transformed bainitic microstructure obtained at a relatively high temperature present a textured morphology. The chaotic growth orientations of the sheaves and the island like of the retained austenite have been observed at the low transformation temperature. A simple model has been established to describe the microstructures and the bainite sheaves growth evolutions during the isothermal holding at the different transformed temperatures. The morphology and distribution of the bainite in the coatings were analyzed by using the nucleation and growth rate of bainitic transformation theories, which is consisted with the experiment results.

Effects of isothermal heat treatment on nanostructured bainite morphology and microstructures in laser cladded coatings

Energy Technology Data Exchange (ETDEWEB)

Guo, Yanbing [Shanghai Key Lab of Materials Laser Processing and Modification, School of Materials Science and Engineering, Shanghai Jiao Tong University, Shanghai 200240 (China); Feng, Kai; Lu, Fenggui; Zhang, Ke [Shanghai Key Lab of Materials Laser Processing and Modification, School of Materials Science and Engineering, Shanghai Jiao Tong University, Shanghai 200240 (China); State Key Laboratory of Metal Matrix Composite, School of Materials Science and Engineering, Shanghai Jiao Tong University, Shanghai 200240 (China); Li, Zhuguo, E-mail: lizg@sjtu.edu.cn [Shanghai Key Lab of Materials Laser Processing and Modification, School of Materials Science and Engineering, Shanghai Jiao Tong University, Shanghai 200240 (China); Hosseini, Seyed Reza Elmi [Shanghai Key Lab of Materials Laser Processing and Modification, School of Materials Science and Engineering, Shanghai Jiao Tong University, Shanghai 200240 (China); Wang, Min [Shanghai Key Lab of Materials Laser Processing and Modification, School of Materials Science and Engineering, Shanghai Jiao Tong University, Shanghai 200240 (China); State Key Laboratory of Metal Matrix Composite, School of Materials Science and Engineering, Shanghai Jiao Tong University, Shanghai 200240 (China)

2015-12-01

Highlights: • Nanobainitic coatings under 200, 250 and 300 °C heat treatments are fabricated. • The size of bainite sheaves increased with the isothermal temperature increasing. • Textured and chaotic distributions are observed in 200 and 300 °C microstructures. • The evolution model of nanobainite morphology is established and analyzed. • The bainitic ferrite of 200 °C heat treatment has a true thickness of 45 nm. - Abstract: Laser cladding and subsequent isothermal heat treatments have been used to fabricate nanostructured bainitic coatings. XRD has been used to determine the kinetics of bainitic transformation process. OM, SEM and TEM have been used to characterize the morphology and microstructures at different stages of transformation. The results showed that at the initial stage of bainitic transformation, the bainite sheaves are short and thin at a relatively low transformation temperature. The fully transformed bainitic microstructure obtained at a relatively high temperature present a textured morphology. The chaotic growth orientations of the sheaves and the island like of the retained austenite have been observed at the low transformation temperature. A simple model has been established to describe the microstructures and the bainite sheaves growth evolutions during the isothermal holding at the different transformed temperatures. The morphology and distribution of the bainite in the coatings were analyzed by using the nucleation and growth rate of bainitic transformation theories, which is consisted with the experiment results.

Correlative SEM SERS for quantitative analysis of dimer nanoparticles.

Science.gov (United States)

Timmermans, F J; Lenferink, A T M; van Wolferen, H A G M; Otto, C

2016-11-14

A Raman microscope integrated with a scanning electron microscope was used to investigate plasmonic structures by correlative SEM-SERS analysis. The integrated Raman-SEM microscope combines high-resolution electron microscopy information with SERS signal enhancement from selected nanostructures with adsorbed Raman reporter molecules. Correlative analysis is performed for dimers of two gold nanospheres. Dimers were selected on the basis of SEM images from multi aggregate samples. The effect of the orientation of the dimer with respect to the polarization state of the laser light and the effect of the particle gap size on the Raman signal intensity is observed. Additionally, calculations are performed to simulate the electric near field enhancement. These simulations are based on the morphologies observed by electron microscopy. In this way the experiments are compared with the enhancement factor calculated with near field simulations and are subsequently used to quantify the SERS enhancement factor. Large differences between experimentally observed and calculated enhancement factors are regularly detected, a phenomenon caused by nanoscale differences between the real and 'simplified' simulated structures. Quantitative SERS experiments reveal the structure induced enhancement factor, ranging from ∼200 to ∼20 000, averaged over the full nanostructure surface. The results demonstrate correlative Raman-SEM microscopy for the quantitative analysis of plasmonic particles and structures, thus enabling a new analytical method in the field of SERS and plasmonics.

Femtosecond laser additive manufacturing of YSZ

Energy Technology Data Exchange (ETDEWEB)

Liu, Jian; Bai, Shuang [PolarOnyx, Inc., San Jose, CA (United States)

2017-04-15

Laser additive manufacturing (LAM) of Yttria-Stabilized Zirconia (YSZ) is investigated using femtosecond (fs) fiber lasers. Various processing conditions are studied, which leads to desired characteristics in terms of morphology, porosity, hardness, microstructural and mechanical properties of the processed components. High-density (>99%) YSZ part with refined grain and increased hardness was obtained. Microstructure features of fabricated specimens were studied with SEM, EDX, the measured micro hardness is achieved as high as 18.84 GPa. (orig.)

Study in vitro of dental enamel irradiated with a high power diode laser operating at 960 nm: morphological analysis of post-irradiation dental surface and thermal effect analysis in pulp chamber due to laser application

International Nuclear Information System (INIS)

Quinto Junior, Jose

2001-01-01

Objectives: This study examines the structural and thermal modifications induced in dental enamel under dye assisted diode laser irradiation. The aim of this study is to verify if this laser-assisted treatment is capable to modify the enamel surface by causing fusion of the enamel surface layer. At the same time, the pulpal temperature rise must be kept low enough in order not to cause pulpar necrosis. To achieve this target, it is necessary to determine suitable laser parameters. As is known, fusion of the enamel surface followed by re-solidification produce a more acid resistant layer. This surface treatment is being researched as a new method for caries prevention. Method and Materials: A series of fourteen identically prepared enamel samples of human teeth were irradiated with a high power diode laser operating at 960 nm and using fiber delivery. Prior to irradiation, a fine layer of cromophorous ink was applied to the enamel surface. In the first part of the experiment the best parameter for pulse duration was determined. In the second part of the experimental phase the same energy density was used but with different repetition rates. During irradiation we monitored the temperature rise in the pulpal cavity. The morphology of the treated samples was analysed under SEM. Results: The morphology of the treated samples showed a homogeneously re-solidified enamel layer. The results of the temperature analysis showed a decrease of the pulpal temperature rise with decreasing repetition rate. Conclusion: With the diode laser it is possible to cause morphological alterations of the enamel surface, which is known to increase the enamel resistance against acid attack, and still maintain the temperature rise in the pulpar chamber below damage threshold. (author)

Study on boron-film thermal neutron converter prepared by pulsed laser deposition

International Nuclear Information System (INIS)

Song Zifeng; Ye Shuzhen; Chen Ziyu; Song Liao; Shen Ji

2011-01-01

The boron film converter used in the position-sensitive thermal neutron detector is discussed and the method of preparing this converter layer via Pulsed Laser Deposition (PLD) is introduced. The morphology and the composition were studied by Scanning Electron Microscopy (SEM) and X-ray Photoelectron Spectroscopy (XPS). Both boron and boride existed on the layer surface. It was shown that the energy intensity of laser beam and the substrate temperature both had an important influence on the surface morphology of the film.

Study on boron-film thermal neutron converter prepared by pulsed laser deposition

Energy Technology Data Exchange (ETDEWEB)

Song Zifeng; Ye Shuzhen; Chen Ziyu; Song Liao [Department of Modern Physics, University of Science and Technology of China, Anhui Hefei 230026 (China); Shen Ji, E-mail: shenji@ustc.edu.c [Department of Modern Physics, University of Science and Technology of China, Anhui Hefei 230026 (China)

2011-02-15

The boron film converter used in the position-sensitive thermal neutron detector is discussed and the method of preparing this converter layer via Pulsed Laser Deposition (PLD) is introduced. The morphology and the composition were studied by Scanning Electron Microscopy (SEM) and X-ray Photoelectron Spectroscopy (XPS). Both boron and boride existed on the layer surface. It was shown that the energy intensity of laser beam and the substrate temperature both had an important influence on the surface morphology of the film.

Studies on mechanical properties, microstructure and fracture morphology details of laser beam welded thick SS304L plates for fusion reactor applications

Energy Technology Data Exchange (ETDEWEB)

Buddu, Ramesh Kumar, E-mail: buddu@ipr.res.in [Fusion Reactor Materials Development and Characterization Division, Institute for Plasma Research, Bhat, Gandhinagar 382428 (India); Chauhan, N.; Raole, P.M. [Fusion Reactor Materials Development and Characterization Division, Institute for Plasma Research, Bhat, Gandhinagar 382428 (India); Natu, Harshad [Magod Laser Machining Pvt. Ltd, Jigani, Bengaluru 560105 (India)

2015-06-15

Highlights: • CO{sub 2} laser welding of 8 mm thick SS304L plates has been carried out and full penetration welds fabricated and characterized for mechanical properties and microstructure details. • Welded samples have shown tensile properties comparable to base indicating good weld quality joints. • Impact fracture tests of weld zone and heat affected zone samples have shown poor toughness compared to the base metal. • SEM analysis of fracture samples of tensile and impact specimens indicated the complex microstructure features in weld zone and combined ductile and brittle fracture features. • Combined features of dendrite and cellular structures are observed in weld microstructures with narrow HAZ and delta ferrite is found in the welds and further confirmed by higher Ferrite Number data. - Abstract: Austenitic stainless steel is widely used structural material for the fabrication of the fusion reactor components. Laser welding is high power density process which offers several advantages over the other conventional processes like Tungsten Inert Gas welding. The features like low distortion, narrow heat affected zone, deep penetration in single pass, good mechanical properties are some of the advantages of laser welding process. The laser weld process parameters optimization has several challenges in terms of overcoming the weld defects like voids due to lack of penetration over depth, undercuts and porosity. The present paper reports the studies carried out with CO{sub 2} laser welding of 8 mm thick austenitic stainless steel SS304L plates and their characterization of mechanical properties, microstructure and fracture morphology details. The weld process parameter optimization towards defect free welds with full penetration welding has been carried out. The welded samples have shown tensile properties comparable to base metal, bend tests are successfully passed. The hardness measurements have shown slightly higher for weld zone compared to base metal

Studies on mechanical properties, microstructure and fracture morphology details of laser beam welded thick SS304L plates for fusion reactor applications

International Nuclear Information System (INIS)

Buddu, Ramesh Kumar; Chauhan, N.; Raole, P.M.; Natu, Harshad

2015-01-01

Highlights: • CO 2 laser welding of 8 mm thick SS304L plates has been carried out and full penetration welds fabricated and characterized for mechanical properties and microstructure details. • Welded samples have shown tensile properties comparable to base indicating good weld quality joints. • Impact fracture tests of weld zone and heat affected zone samples have shown poor toughness compared to the base metal. • SEM analysis of fracture samples of tensile and impact specimens indicated the complex microstructure features in weld zone and combined ductile and brittle fracture features. • Combined features of dendrite and cellular structures are observed in weld microstructures with narrow HAZ and delta ferrite is found in the welds and further confirmed by higher Ferrite Number data. - Abstract: Austenitic stainless steel is widely used structural material for the fabrication of the fusion reactor components. Laser welding is high power density process which offers several advantages over the other conventional processes like Tungsten Inert Gas welding. The features like low distortion, narrow heat affected zone, deep penetration in single pass, good mechanical properties are some of the advantages of laser welding process. The laser weld process parameters optimization has several challenges in terms of overcoming the weld defects like voids due to lack of penetration over depth, undercuts and porosity. The present paper reports the studies carried out with CO 2 laser welding of 8 mm thick austenitic stainless steel SS304L plates and their characterization of mechanical properties, microstructure and fracture morphology details. The weld process parameter optimization towards defect free welds with full penetration welding has been carried out. The welded samples have shown tensile properties comparable to base metal, bend tests are successfully passed. The hardness measurements have shown slightly higher for weld zone compared to base metal and the

Cemented carbide cutting tool: Laser processing and thermal stress analysis

Energy Technology Data Exchange (ETDEWEB)

Yilbas, B.S. [Mechanical Engineering Department, KFUPM, Box 1913, Dhahran 31261 (Saudi Arabia)]. E-mail: bsyilbas@kfupm.edu.sa; Arif, A.F.M. [Mechanical Engineering Department, KFUPM, Box 1913, Dhahran 31261 (Saudi Arabia); Karatas, C. [Engineering Faculty, Hacettepe University, Ankara (Turkey); Ahsan, M. [Mechanical Engineering Department, KFUPM, Box 1913, Dhahran 31261 (Saudi Arabia)

2007-04-15

Laser treatment of cemented carbide tool surface consisting of W, C, TiC, TaC is examined and thermal stress developed due to temperature gradients in the laser treated region is predicted numerically. Temperature rise in the substrate material is computed numerically using the Fourier heating model. Experiment is carried out to treat the tool surfaces using a CO{sub 2} laser while SEM, XRD and EDS are carried out for morphological and structural characterization of the treated surface. Laser parameters were selected include the laser output power, duty cycle, assisting gas pressure, scanning speed, and nominal focus setting of the focusing lens. It is found that temperature gradient attains significantly high values below the surface particularly for titanium and tantalum carbides, which in turn, results in high thermal stress generation in this region. SEM examination of laser treated surface and its cross section reveals that crack initiation below the surface occurs and crack extends over the depth of the laser treated region.

Adapted methods for scanning electron microscopy (SEM in assessment of human sperm morphology

Directory of Open Access Journals (Sweden)

Petra Nussdorfer

2018-02-01

Full Text Available Infertility is a widespread problem, and in some cases, the routine basic semen analysis is not sufficient to detect the cause of male infertility. The use of the scanning electron microscope (SEM could provide a detailed insight into spermatozoa morphology, but it requires specific sample preparation techniques. The purpose of this study was to select, adjust, and optimize a method for the preparation of spermatozoa samples prior to SEM analysis, and to establish the protocol required for its use in clinical practice. We examined sperm samples of 50 men. The samples were fixed with modified iso-osmolar aldehyde solution followed by osmium post-fixation. In the first method, dehydration of the cells and subsequent critical point drying (CPD were performed on a coverslip. In the second method, the samples were dehydrated in centrifuge tubes; hexamethyldisilazane (HMDS was used as a drying agent instead of CPD, and the samples were air-dried. The third procedure was based on a membrane filter. The samples were dehydrated and dried with HMDS in a Gooch crucible, continuously, without centrifugation or redispersion of the sample. Our results showed that the fixation with modified iso-osmolar aldehyde solution followed by osmium post-fixation, and combined with dehydration and CPD on a coverslip, is the most convenient procedure for SEM sample preparation. In the case of small-size samples or low sperm concentration, dehydration and drying with HMDS on the membrane filter enabled the best reliability, repeatability, and comparability of the results. The presented procedures are suitable for routine use, and they can be applied to confirm as well as to correct a diagnosis.

Surface morphology of thin lysozyme films produced by matrix-assisted pulsed laser evaporation (MAPLE)

DEFF Research Database (Denmark)

Purice, Andreea; Schou, Jørgen; Pryds, Nini

2007-01-01

Thin films of the protein, lysozyme, have been deposited by the matrix-assisted pulsed laser evaporation (MAPLE) technique. Frozen targets of 0.3-1.0 wt.% lysozyme dissolved in ultrapure water were irradiated by laser light at 355 mn with a fluence of 2 J/cm(2). The surface quality of the thin....... The concentration of lysozyme in the ice matrix apparently does not play any significant role for the morphology of the film. The morphology obtained with MAPLE has been compared with results for direct laser irradiation of a pressed lysozyme sample (i.e. pulsed laser deposition (PLD)). (C) 2007 Elsevier B.V. All...

Evaluation of the morphological alteration of the root surface radiated with a diode laser

International Nuclear Information System (INIS)

Gulin, Mauricio

2003-01-01

The diode laser has been studied for periodontal therapy, as much for removal of calculus as for microbial reduction of periodontal pockets, as well as the visible analgesic effects and biomodulation capacity. For this reason the purpose of this study was to evaluate the morphological alteration of the root surface after radiation with the diode laser, 808 nm through analysis by scanning electron microscopy (SEM). Besides this, to verify the temperature variations caused during the radiation, a thermometer put into the dentinal wall of the root canal was used. In all, 18 teeth were used, 15 of which for the SEM study, and the other 3 were used to temperature variation analysis. The 25 samples were scraped on the root surface and planed with manual instruments. The other 5 were not subjected to any type of treatment. This, 6 groups of 5 samples each were formed. Control Group C whose samples had not received any treatment; Control Group C 1 was only scraped and polished conventionally with Hu-Friedy Gracey curettes 5 and 6; the other samples groups L1, L2, L3, L4 were radiated by diode laser using parameters of power 1,0 W; 1,2 W; 1,4 W; and 1,6 W respectively, 2 times for 10 seconds with 20 seconds intervals between each radiation in continuous mode. The results with relation to the increase of temperature in the interior of the root canal demonstrated that there was an increase of more than 5 degree Celsius. The results of the scanning electron microscope analysis of Control Group C demonstrated great irregularity and ridges on the root surface, with the presence of a dentine layer. Control Group C1 presented a similar aspect to Group L 1's, smoother and more homogeneous surface. Groups L2, L3, and L4 presented scratches alternating with smoother areas showing that fiber contacted the surface of the sample. The results reconfirmed the necessity of further studies using diode laser, with a beam of light emitted in an interrupted mode to improve the control of the

Structure and Morphology Effects on the Optical Properties of Bimetallic Nanoparticle Films Laser Deposited on a Glass Substrate

Directory of Open Access Journals (Sweden)

A. O. Kucherik

2017-01-01

Full Text Available Moving nanosecond laser system is used for laser-assisted thermodiffusion deposition of metallic nanoparticles from water-based colloidal solutions. The results obtained for both gold and silver nanoparticles show that film morphology strongly depends on laser scanning speed and the number of passages. We show, furthermore, the possibility of producing bimetallic Au:Ag thin films by laser irradiation of the mixed solutions. As a result of several laser scans, granular nanometric films are found to grow with a well-controlled composition, thickness, and morphology. By changing laser scanning parameters, film morphology can be varied from island structures to quasi-periodic arrays. The optical properties of the deposited structures are found to depend on the film composition, thickness, and mean separation between the particles. The transparency spectra of the deposited films are shown to be defined by their morphology.

Morphological evaluation of cavity preparation surface after duraphat and Er:YAG laser treatment by scanning electronic microscopy; Avaliacao das alteracoes morfologicas da superficie do preparo cavitario apos condicionamento com verniz fluoretado a 2,26 % e laser de Er:YAG atraves de microscopia eletronica de varredura

Energy Technology Data Exchange (ETDEWEB)

Rodrigues, Luciane Borelli

2002-07-01

The treatment of dental surface using different lasers to prevent dental caries has been studied for several on last years. The purpose of this in vitro study was to evaluate the morphological changes on dentin surface from pulpal wall of cavity preparations performed by high-speed drill, treated with 2,26% fluoride varnish (Duraphat) and Er:YAG laser, and then submitted after receiving or not to EDTA 15% treatment. Twenty Class V cavities were performed on ten humans molars. The specimens were randomly divided in to 4 groups: group 1- treatment with Duraphat followed by Er:YAG laser irradiation (120 mJ/ 4 Hz); group 2: Er:YAG laser irradiation, same parameters, followed by Duraphat treatment; group 3- same group 1 followed by immersion in EDTA (5 min); group 4 - same as group 2 followed by immersion in EDTA (5 min). The specimens were processed for SEM analysis. The micrographs showed that Duraphat treatment promoted morphological changes on dentin, closing dentinal tubules; the specimens treated by Duraphat and Er:YAG laser and immersed in EDTA (group 3) showed homogeneous surface, closed and protected dentinal tubules, maintenance of the fluoride varnish on the dentin surface and around the dentinal tubules, showing feasible and efficiency of these therapies the feasibility.(author)

Darkening effect on AZ31B magnesium alloy surface induced by nanosecond pulse Nd:YAG laser

Energy Technology Data Exchange (ETDEWEB)

Guan, Y.C., E-mail: guan0013@e.ntu.edu.sg [School of Mechanical and Aerospace Engineering, Nanyang Technological University, 50 Nanyang Avenue, Singapore 639798 (Singapore); Singapore Institute of Manufacturing Technology, 71 Nanyang Drive, Singapore 638075 (Singapore); Zhou, W. [School of Mechanical and Aerospace Engineering, Nanyang Technological University, 50 Nanyang Avenue, Singapore 639798 (Singapore); Singapore Institute of Manufacturing Technology, 71 Nanyang Drive, Singapore 638075 (Singapore); Zheng, H.Y.; Li, Z.L. [Singapore Institute of Manufacturing Technology, 71 Nanyang Drive, Singapore 638075 (Singapore)

2013-09-01

Permanent darkening effect was achieved on surface of AZ31B Mg alloy irradiated with nanosecond pulse Nd:YAG laser, and special attention was made to examine how surface structure as well as oxidation affect the darkening effect. Experiments were carried out to characterize morphological evolution and chemical composition of the irradiated areas by optical reflection spectrometer, Talysurf surface profiler, SEM, EDS, and XPS. The darkening effect was found to be occurred at the surface under high laser energy. Optical spectra showed that the induced darkening surface was uniform over the spectral range from 200 nm to 1100 nm. SEM and surface profiler showed that surface morphology of darkening areas consisted of large number of micron scale cauliflower-like clusters and protruding particles. EDS and XPS showed that compared to non-irradiated area, oxygen content at the darkening areas increased significantly. It was proposed a mechanism that involved trapping of light in the surface morphology and chemistry variation of irradiated areas to explain the laser-induced darkening effect on AZ31B Mg alloy.

Comparative study of etched enamel and dentin for the adhesion of composite resins with the Er:YAG 2,94 {mu}m laser and CO{sub 2} 9,6 {mu}m laser: morphological (SEM) and tensile bond strength analysis; Estudo comparativo do condicionamento do esmalte e dentina para a adesao de resinas compostas com os lasers Er:YAG 2,94 {mu}m e com o laser CO{sub 2} de 9,6 {mu}m: analise morfologica e de resistencia a tracao

Energy Technology Data Exchange (ETDEWEB)

Marraccini, Tarso Mugnai

2002-07-01

The aim of this study was to evaluate and compare the tensile bond strength of a composite resin adhered to the enamel and dentin which have received superficial irradiation with an Er:YAG laser (2.94 {mu}m) or with CO{sub 2} laser ( 9.6 {mu}m) and later on etched with the phosphoric acid at 35%. After the use of the adhesive system, resin cones were made on the etched surfaces by both lasers and tensile bond strength tests were performed. All samples were observed at the SEM - there was an increase of the degree of fusion and resolidification in the irradiated enamel and dentin samples with the CO{sub 2} laser (9.6 {mu}m), creating a vitrified layer with tiny craters. With the Er:YAG laser (2.94 {mu}m) there were typical morphological explosive microablation with the exposition of the tubules in the dentin.The surface acquired by the association of the CO{sub 2} laser ( 9.6 {mu}m) plus acid etching no longer presented the aspect of fusion being this layer completely removed. There were statistical significant differences among ali three methods of etching in the treatment of the enamel and dentin surface. The tensile bond strength test showed that etching of these enamel and dentin surfaces with acid exclusively (control group) presented great values, surpassing the values of the etching acquired with the Er:YAG laser (2.94 {mu}) plus acid or the CO{sub 2} laser (9.6 {mu}m) plus acid. With the parameters used in this experiment the Er:YAG laser (2.94 {mu}m) showed to be more effective than the CO{sub 2} laser (9.6 {mu}m) for the hard dental surfaces etching procedure. (author)

The influence of a novel in-office tooth whitening procedure using an Er,Cr:YSGG laser on enamel surface morphology.

Science.gov (United States)

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 (Pwhitening 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 (Pwhitening 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.

In vitro evaluation of the morphologic changes on the root dentine irradiated by CO2 laser associated or not to calcium hydroxide application

International Nuclear Information System (INIS)

Romano, Ana Cristina Cury Camargo

2003-01-01

This in vitro study has evaluated the structural changes on the root dentine irradiated by a CO 2 laser associated or not to calcium hydroxide application, from the irradiated surface analysis by means of Scanning Electronic Microscopy (SEM). The purpose of this evaluation has been the study of an alternative method for the treatment of dentine hypersensitivity. Fourteen human teeth were utilized, third molars, divided into 7 groups. Group I (control group) to which no treatment was applied; Groups II, III and IV were given an application of Ca (OH) 2 paste followed by C0 2 laser irradiation, lasting 5 seconds each with intervals of 10 seconds between each application, with continuous emission, power of 0.5 W (Group II), 1.0 W (Group III), and 1.5 W (Group IV); Groups V, VI, and VII were given laser irradiations without the Ca (OH) 2 paste following the same parameters applied to groups II, III, and IV respectively. Morphologic changes suggesting to fusion and re-solidification have been observed, as well as the presence of material obstructing the whole analyzed surface on groups II, III, and IV (laser + Ca (OH) 2 ). As for groups V, VI, and VII, it has been observed fusion, re-solidification, and cracks, and these results being statistically significant when compared the '(Ca (OH) 2 )' groups to the laser groups. No statistically significant differences were observed regarding the different powers applied in the groups that used the same treatment. Despite this result, it can be stated that powers above 1.0 W (DP = 125,38 W/cm 2 ) are unfavorable due to the undesirable morphologic alterations and aesthetic compromising. (author)

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

Energy Technology Data Exchange (ETDEWEB)

Zorko, Milena [National Institute of Chemistry, Hajdrihova 19, Ljubljana (Slovenia); Centre of Excellence for Low-Carbon Technologies, Hajdrihova 19, Ljubljana (Slovenia); Jozinović, Barbara [Centre of Excellence for Low-Carbon Technologies, Hajdrihova 19, Ljubljana (Slovenia); Bele, Marjan [National Institute of Chemistry, Hajdrihova 19, Ljubljana (Slovenia); Centre of Excellence for Low-Carbon Technologies, Hajdrihova 19, Ljubljana (Slovenia); Hodnik, Nejc, E-mail: nejc.hodnik@ki.si [National Institute of Chemistry, Hajdrihova 19, Ljubljana (Slovenia); Gaberšček, Miran [National Institute of Chemistry, Hajdrihova 19, Ljubljana (Slovenia); Centre of Excellence for Low-Carbon Technologies, Hajdrihova 19, Ljubljana (Slovenia)

2014-05-01

A general method for tracking morphological surface changes on a nanometer scale with scanning electron microscopy (SEM) is introduced. We exemplify the usefulness of the method by showing consecutive SEM images of an identical location before and after the electrochemical and thermal treatments of platinum-based nanoparticles deposited on a high surface area carbon. Observations reveal an insight into platinum based catalyst degradation occurring during potential cycling treatment. The presence of chloride clearly increases the rate of degradation. At these conditions the dominant degradation mechanism seems to be the platinum dissolution with some subsequent redeposition on the top of the catalyst film. By contrast, at the temperature of 60 °C, under potentiostatic conditions some carbon corrosion and particle aggregation was observed. Temperature treatment simulating the annealing step of the synthesis reveals sintering of small platinum based composite aggregates into uniform spherical particles. The method provides a direct proof of induced surface phenomena occurring on a chosen location without the usual statistical uncertainty in usual, random SEM observations across relatively large surface areas. - Highlights: • A new SEM method for observations of identical locations. • Nanoscale morphological consecutive changes on identical locations. • Electrochemical and thermal treatments on platinum based nanoparticles. • Potential cycling induces platinum dissolution with redeposition on top of the film. • At 1.4 V vs. RHE and 60 °C carbon corrosion and particle aggregation is observed.

Fibre laser cutting stainless steel: Fluid dynamics and cut front morphology

Science.gov (United States)

Pocorni, Jetro; Powell, John; Deichsel, Eckard; Frostevarg, Jan; Kaplan, Alexander F. H.

2017-01-01

In this paper the morphology of the laser cut front generated by fibre lasers was investigated by observation of the 'frozen' cut front, additionally high speed imaging (HSI) was employed to study the fluid dynamics on the cut front while cutting. During laser cutting the morphology and flow properties of the melt film on the cut front affect cut quality parameters such as cut edge roughness and dross (residual melt attached to the bottom of the cut edge). HSI observation of melt flow down a laser cutting front using standard cutting parameters is experimentally problematic because the cut front is narrow and surrounded by the kerf walls. To compensate for this, artificial parameters are usually chosen to obtain wide cut fronts which are unrepresentative of the actual industrial process. This paper presents a new experimental cutting geometry which permits HSI of the laser cut front using standard, commercial parameters. These results suggest that the cut front produced when cutting medium section (10 mm thick) stainless steel with a fibre laser and a nitrogen assist gas is covered in humps which themselves are covered by a thin layer of liquid. HSI observation and theoretical analysis reveal that under these conditions the humps move down the cut front at an average speed of approximately 0.4 m/s while the covering liquid flows at an average speed of approximately 1.1 m/s, with an average melt depth at the bottom of the cut zone of approximately 0.17 mm.

Experimental sharp force injuries to ribs: Multimodal morphological and geometric morphometric analyses using micro-CT, macro photography and SEM.

Science.gov (United States)

Komo, Larissa; Grassberger, Martin

2018-07-01

Tool marks on bones induced by knife blades can be analysed morphometrically in order to enable an allocation of the suspected "inflicting weapon" to the particular morphology of the bone lesions. Until now, geometric morphometrics has not been used to analyse the morphology of knife lesions on fleshed bones in detail. By using twelve experimental knives and a drop weight tower, stab/cut injuries were inflicted on untreated pig ribs. The morphology of the experimentally produced lesions was subsequently recorded with three imaging techniques (μCT, macro photography and SEM) and analysed with different morphometric software (Amira, tps and Morpheus). Based on the measured distances between the walls of the kerf marks, which corresponded to the thickness of the blade, one could conclude to the respective blade thickness with a deviation of max. ±0.35mm and match the injuries to the knives. With subsequent reanalysis after maceration, an average shrinkage factor up to 8.6% was observed. Among the three imaging techniques used in this study, μCT was the most accurate and efficient technique, particularly because it represented the only non-destructive modality to document injuries without maceration, even though μCT is more expensive and time-consuming as well as less accessible than a macro SLR-camera or a SEM. For optimal characterizations of the blades' and kerfs' shapes the software tps proofed to be the best choice. Accordingly, geometric morphometrics could serve as a tool in forensic investigations concerning kerf marks. Copyright © 2018 Elsevier B.V. All rights reserved.

Improving adhesion of copper/epoxy joints by pulsed laser ablation

KAUST Repository

Hernandez, Edwin

2015-10-19

The purpose of the present work is to analyze the effect of pulsed laser ablation on copper substrates (CuZn40) deployed for adhesive bonding. Surface pre-treatment was carried using an Yb-fiber laser beam. Treated surfaces were probed using Scanning Electron Microscopy (SEM) and X-Ray Photoelectron Spectroscopy (XPS). The mechanical performance of CuZn40/epoxy bonded joints was assessed using the T-peel test coupon. In order to resolve the mechanisms of failure and adhesive penetration within surface asperities induced by the laser treatment, fracture surfaces were surveyed using SEM. Finite element simulations, based on the use of the cohesive zone model of fracture, were carried out to evaluate the variation of bond toughness. Results indicated that the laser ablation process effectively modifies surface morphology and chemistry and enables enhanced mechanical interlocking and cohesive failure within the adhesive layer. Remarkable improvements of apparent peel energy and bond toughness were observed with respect to control samples with sanded substrates.

Improving adhesion of copper/epoxy joints by pulsed laser ablation

KAUST Repository

Hernandez, Edwin; Alfano, Marco; Lubineau, Gilles; Buttner, Ulrich

2015-01-01

The purpose of the present work is to analyze the effect of pulsed laser ablation on copper substrates (CuZn40) deployed for adhesive bonding. Surface pre-treatment was carried using an Yb-fiber laser beam. Treated surfaces were probed using Scanning Electron Microscopy (SEM) and X-Ray Photoelectron Spectroscopy (XPS). The mechanical performance of CuZn40/epoxy bonded joints was assessed using the T-peel test coupon. In order to resolve the mechanisms of failure and adhesive penetration within surface asperities induced by the laser treatment, fracture surfaces were surveyed using SEM. Finite element simulations, based on the use of the cohesive zone model of fracture, were carried out to evaluate the variation of bond toughness. Results indicated that the laser ablation process effectively modifies surface morphology and chemistry and enables enhanced mechanical interlocking and cohesive failure within the adhesive layer. Remarkable improvements of apparent peel energy and bond toughness were observed with respect to control samples with sanded substrates.

Morphological changes in skin tumors caused by pulsed laser irradiation

Energy Technology Data Exchange (ETDEWEB)

Moskalik, K G; Lipova, V A; Neyshtadt, E L

1979-01-01

Morphological changes induced by treating melanomas, basaloma and flatcell skin cancers with a pulsed neodymium laser at 1060 nm, pulse length 1 msec and energy 250 to 500 J/cm/sup 2/, were studied using impressions and scrapings from the affected area. Nuclear pyknosis, nuclear and cellular elongation, vacuolization, frequent complete loss of cytoplasm, particulaly in the zone of direct irradiation, and loss of cellular structure were seen. These dystrophic changes increased with closeness to the zone of direct irradiation, culminating in necrosis. Formed and decomposed blood elements and melanin accumulated in the intracellular spaces, due to disruption of capillaries and small arteries and veins. Fewer and more aggregated melanoblasts were found after melanoma irradiation. Nuclear chromatin fusion, cytoplasmic changes and altered cell shape were observed. Basaloma cells were clustered and elongated after irradiation, with many fibrous structures and loss of cellular elements. Cytoplasmic vacuolization and lysis, bare nuclei, karyolysis, karyorrhexis and karyopyknosis were seen in corneous flat-cell cancer. In the few cases in which malignant cells were found under the scab from the first treatment the procedure was repeated. The morphological changes induced by pulsed laser irradiation are very similar to electrocoagulation necrosis, but are more localized. The ability of low and middle energy lasers to induce thrombosis and coagulation in vascular walls reduced the probability of hematogenic tumor cell dissemination. Cytological examination is highly effective in determining the degree of radical skin cancer healing due to laser treatment. 12 references, 2 figures.

Influence of laser surface modifying of polyethylene terephthalate on fibroblast cell adhesion

International Nuclear Information System (INIS)

Mirzadeh, H.; Dadsetan, M.

2003-01-01

Attempts have been made to evaluate the changes in physical and chemical properties of the polyethylene terephthalate (PET) surface due to laser irradiation. These changes have been investigated from viewpoints of microstructuring and its effect on fibroblast cell behavior. The surfaces of PET were irradiated using CO 2 and KrF excimer pulsed laser. The changes were characterized by attenuated total reflectance Fourier transform infrared (ATR-FTIR) spectroscopy, scanning electron microscopy (SEM) and contact angle measurements. The data from ATR-FTIR spectra showed that the crystallinity in the surface region decreased due to the CO 2 and excimer laser irradiation. SEM observations showed that specific microstructures were created on the PET surface due to laser irradiation. In order to study biocompatibility and cell behavior, we utilized standard in vitro L929-fibroblast cell culture system. Fibroblast cell adhesion and spreading were significantly correlated to the morphology and wettability of the laser irradiated PET surface

Effect of laser irradiation on the structural, morphological and electrical properties of polycrystalline TiO2 thin films

Directory of Open Access Journals (Sweden)

M.I. Khan

Full Text Available TiO2 thin film is deposited on glass substrate by sol-gel dip coating technique. After deposition, films were irradiated by continuous wave (CW diode laser at an angle of 45°. XRD shows both the anatase and brookite phases of TiO2. Nano particles of regular and control sizes are appeared in SEM micrographs. Therefore, shape and size of nano particles can be control by using Laser irradiation. The average sheet resistivity of TiO2 thin film irradiated by 0, 2, 4 and 6 min are 6.72 × 105, 5.32 × 105, 3.44 × 105 and 4.95 × 105 (ohm-m respectively, according to four point probe. Keywords: TiO2, Diode laser, XRD, SEM

[Effects of Nd: YAG laser irradiation on the root surfaces and adhesion of Streptococcus mutans].

Science.gov (United States)

Yuanhong, Li; Zhongcheng, Li; Mengqi, Luo; Daonan, Shen; Shu, Zhang; Shu, Meng

2016-12-01

This study aimed to evaluate the effects of treatment with different powers of Nd: YAG laser irradiation on root surfaces and Streptococcus mutans (S. mutans) adhesion. Extracted teeth because of severe periodontal disease were divided into the following four groups: control group, laser group 1, laser group 2, and laser group 3. After scaling and root planning, laser group 1, laser group 2, and laser group 3 were separately treated with Nd: YAG laser irradiation (4/6/8 W, 60 s); however, the control group did not receive the treatment. Scanning electron microscopy (SEM) was used to determine the morphology. S. mutans were cultured with root slices from each group. Colony forming unit per mL (CFU·mL⁻¹) was used to count and compare the amounts of bacteria adhesion among groups. SEM was used to observe the difference of bacteria adhesion to root surfaces between control group (scaling) and laser group 2 (6 W, 60 s), thereby indicating the different bacteria adhesions because of different treatments. Morphology alterations indicated that root surfaces in control group contain obvious smear layer, debris, and biofilm; whereas the root surfaces in laser group contain more cracks with less smear layer and debris. The bacteria counting indicated that S. mutans adhesion to laser group was weaker than that of control group (P0.05) was observed. Morphology alterations also verified that S. mutans adhesion to laser group 2 (6 W, 60 s) was weaker than that of control group (scaling). This study demonstrated that Nd: YAG laser irradiation treatment after scaling can reduce smear layer, debris, and biofilm on the root surfaces as compared with conventional scaling. The laser treatment reduces the adhesion of S. mutans as well. However, Nd: YAG laser irradiation can cause cracks on the root surfaces. In this experiment, the optimum laser power of 6 W can thoroughly remove the smear layer and debris, as well as relatively improve the control of thermal damagee.

Fs-laser processing of medical grade polydimethylsiloxane (PDMS)

Energy Technology Data Exchange (ETDEWEB)

Atanasov, P.A., E-mail: paatanas@ie.bas.bg [Institute of Electronics, Bulgarian Academy of Sciences, 72 Tsaridradsko shose Blvd., Sofia 1784 (Bulgaria); Stankova, N.E.; Nedyalkov, N.N. [Institute of Electronics, Bulgarian Academy of Sciences, 72 Tsaridradsko shose Blvd., Sofia 1784 (Bulgaria); Fukata, N. [International Centre for Materials for NanoArchitectonics (MANA), National Institute for Materials Science (NIMS), 1-1Namiki, Tsukuba 305-0044 (Japan); Hirsch, D.; Rauschenbach, B. [Leibniz Institute of Surface Modification (IOM), Permoserstrasse 15, D-04318 Leipzig (Germany); Amoruso, S.; Wang, X. [Dipartimento di Fisica Università degli Studi di Napoli Federico II and CNR-SPIN, Complesso Universitario di Monte S.Angelo, Via Cintia, I-80126 Napoli (Italy); Kolev, K.N.; Valova, E.I.; Georgieva, J.S.; Armyanov, St.A. [Rostislaw Kaischew Institute of Physical Chemistry, Bulgarian Academy of Sciences, Acad. G. Bonchev Str., Block 11, Sofia 1113 (Bulgaria)

2016-06-30

Highlights: • Fs-laser (263, 527 and 1055 nm) processing of PDMS-elastomer is studied. • High quality trenches are produced on the PDMS surface. • The trenches are analyzed by Laser Microscope and by μ-Raman spectrometry. • Selective Ni metallization of the trenches is accomplished via electro-less plating. • The metalized trenches are studied by SEM. - Abstract: Medical grade polydimethylsiloxane (PDMS) elastomer is a biomaterial widely used in medicine and high-tech devices, e.g. MEMS and NEMS. In this work, we report an experimental investigation on femtosecond laser processing of PDMS-elastomer with near infrared (NIR), visible (VIS) and ultraviolet (UV) pulses. High definition trenches are produced by varying processing parameters as laser wavelength, pulse duration, fluence, scanning speed and overlap of the subsequent pulses. The sample surface morphology and chemical composition are investigated by Laser Microscopy, SEM and Raman spectroscopy, addressing the effects of the various processing parameters through comparison with the native materials characteristics. For all the laser pulse wavelengths used, the produced tracks are successfully metalized with Ni via electro-less plating method. We observe a negligible influence of the time interval elapsed between laser treatment and metallization process. Our experimental findings suggest promising perspectives of femtosecond laser pulses in micro- and nano-fabrication of hi-tech PDMS devices.

Morphology and transmittance of porous alumina on glass substrate

Energy Technology Data Exchange (ETDEWEB)

Guo Peitao, E-mail: guopeitao@hotmail.com [Wuhan University of Technology. Wuhan (China); Xia Zhilin [Wuhan University of Technology. Wuhan (China); Key Laboratory of Low Dimensional Materials and Application Technology, Xiangtan University, Ministry of Education, Xiangtan (China); Xue Yiyu [Wuhan University of Technology. Wuhan (China); Huang Caihua [China Three Gorges University, Yichang (China); Zhao Lixin [Wuhan University of Technology. Wuhan (China)

2011-02-01

The porous optical film has higher threshold of laser-induced damage than densified films, for the study of mechanism of laser-induced damage of porous optical film with ordered pore structure. Porous anodic alumina (PAA) film with high transmittance on glass substrate has been prepared. Aluminum film was deposited on glass substrate by means of resistance and electron beam heat (EBH) evaporation. Porous alumina was prepared in oxalic acid solution under different anodizing conditions. At normal incidence, the optical transmittance spectrum over 300-1000 nm spectra region was obtained by spectrophotometer. SEM was introduced to analysis the morphology of the porous alumina film. The pore aperture increased with the increase of anodizing voltage, which resulted in a rapid decrease of the pore concentration and the optical thickness of porous alumina film. Damage morphology of porous alumina film is found to be typically defects initiated, and the defect is the pore presented on the film.

Clinical and morphologic evaluation of Er:YAG laser action at the front of cervical dentinal hypersensitivity

International Nuclear Information System (INIS)

Rocha, Dalva Maria

2001-01-01

This work was achieved in vivo and in vitro to evaluate the efficiency of Er:YAG laser in the cervical dentinal hypersensitivity treatment (HSDC). The Clinical study was achieved in patients with HSDC. The treatment was realized in five sessions: the first for selection, the second for exams (clinic and X-Ray) and trying to remove the etiologic factors that could cause the HSDC. The third and fourth sessions were subjected to the radiation with that protocol: 60 mJ energy ,2 Hz frequency, 6 mm out of focus, under air cooling, 20 seconds each application which the same was repeated four times with one minute breaks, which scanning movements and without using anaesthetics. The fifth was evaluation. The patients were evaluated and registered in a subject scale of pain 0 to 3, in the beginning and end of each session of irradiation, and one month after the last session. The results showed that for the irradiated group occurs significant differences in the beginning of each session and between. For the control group did not occur significant differences in the beginning and after each session, but did show a difference between the sessions. As the control group as the irradiated group, had reduction of sensibility between the session. For the morphologic study nine teeth were selected, 7 molars and 2 pre-molars from operative dentistry discipline. Half of the surface was irradiated with Er:YAG laser, the same protocol used in vivo, and the other half was used as a control without receiving any laser irradiation. Subsequently, specimens were prepared for SEM examinations. The results showed that laser treated surfaces showed a reduction of dentine tubular diameter with partial or total closure of the dentine tubules. For the control group, it was observed bigger amounts smear layer and open dentine tubular. The results obtained indicated that the Er:YAG laser can contribute to the HSDC treatment. (author)

Influence of CdS nanoparticles grain morphology on laser-induced absorption

Science.gov (United States)

Ebothé, Jean; Michel, Jean; Kityk, I. V.; Lakshminarayana, G.; Yanchuk, O. M.; Marchuk, O. V.

2018-06-01

Using external illumination of a 7 nanosecond (ns) doubled frequency Nd: YAG laser emitting at λ = 532 nm with frequency repetition 10 Hz it was established a possibility of significant changes of the absorption at the probing wavelength 1150 nm of continuous wave (cw) He-Ne laser for the CdS nanoparticles embedded into the PVA polymer matrix. The effect is observed only during the two beam laser coherent treatment and this effect is a consequence of interference of two coherent beams. It is shown a principal role of the grain morphology in the efficiency of the process, which is more important than the nanoparticle sizes. The photoinduced absorption is manifested in the space distribution of the probing laser beam. The principal role of the grain interfaces between the nanoparticle interfaces and the surrounding polymer matrix is shown. The effect is almost independent of the nanoparticle sizes. It may be used for laser operation by nanocomposites.

Study in vitro of dental enamel irradiated with a high power diode laser operating at 960 nm: morphological analysis of post-irradiation dental surface and thermal effect analysis in pulp chamber due to laser application; Estudo in vitro do esmalte dental irradiado com laser de diodo de alta potencia em 960 nm: analise morfologica da superficie dental pos-irradiada e analise do comportamento termico na camara pulpar devido a aplicacao laser

Energy Technology Data Exchange (ETDEWEB)

Quinto Junior, Jose

2001-07-01

Objectives: This study examines the structural and thermal modifications induced in dental enamel under dye assisted diode laser irradiation. The aim of this study is to verify if this laser-assisted treatment is capable to modify the enamel surface by causing fusion of the enamel surface layer. At the same time, the pulpal temperature rise must be kept low enough in order not to cause pulpar necrosis. To achieve this target, it is necessary to determine suitable laser parameters. As is known, fusion of the enamel surface followed by re-solidification produce a more acid resistant layer. This surface treatment is being researched as a new method for caries prevention. Method and Materials: A series of fourteen identically prepared enamel samples of human teeth were irradiated with a high power diode laser operating at 960 nm and using fiber delivery. Prior to irradiation, a fine layer of cromophorous ink was applied to the enamel surface. In the first part of the experiment the best parameter for pulse duration was determined. In the second part of the experimental phase the same energy density was used but with different repetition rates. During irradiation we monitored the temperature rise in the pulpal cavity. The morphology of the treated samples was analysed under SEM. Results: The morphology of the treated samples showed a homogeneously re-solidified enamel layer. The results of the temperature analysis showed a decrease of the pulpal temperature rise with decreasing repetition rate. Conclusion: With the diode laser it is possible to cause morphological alterations of the enamel surface, which is known to increase the enamel resistance against acid attack, and still maintain the temperature rise in the pulpar chamber below damage threshold. (author)

Correlative microscopy including CLSM and SEM to improve high-speed, high-resolution laser-engraved print and embossing forms

Science.gov (United States)

Bohrer, Markus; Schweitzer, Michael; Nirnberger, Robert; Weinberger, Bernhard

2015-10-01

The industrial market for processing large-scale films has seen dramatic changes since the 1980s and has almost completely been replaced by lasers and digital processes. A commonly used technology for engraving screens, print and embossing forms in the printing industry, well known since then, is the use of RF-excited CO2 lasers with a beam power up to about 1 kW, modulated in accordance to the pattern to be engraved. Future needs for high-security printing (banknotes, security papers, passports, etc.) will require laser engraving of at least half a million or even more structured elements with a depth from some μm up to 500 μm. Industry now wants photorealistic pictures in packaging design, which requires a similar performance. To ensure 'trusted pulses' from the digital process to the print result the use of correlative microscopy (CLSM and SEM) is demonstrated as a complete chain for a correlative print process in this paper.

Evaluation of the morphological alteration of the root surface radiated with a diode laser; Avaliacao da alteracao morfologica da superficie cimentaria irradiada com laser de diodo

Energy Technology Data Exchange (ETDEWEB)

Gulin, Mauricio

2003-07-01

The diode laser has been studied for periodontal therapy, as much for removal of calculus as for microbial reduction of periodontal pockets, as well as the visible analgesic effects and biomodulation capacity. For this reason the purpose of this study was to evaluate the morphological alteration of the root surface after radiation with the diode laser, 808 nm through analysis by scanning electron microscopy (SEM). Besides this, to verify the temperature variations caused during the radiation, a thermometer put into the dentinal wall of the root canal was used. In all, 18 teeth were used, 15 of which for the SEM study, and the other 3 were used to temperature variation analysis. The 25 samples were scraped on the root surface and planed with manual instruments. The other 5 were not subjected to any type of treatment. This, 6 groups of 5 samples each were formed. Control Group C whose samples had not received any treatment; Control Group C 1 was only scraped and polished conventionally with Hu-Friedy Gracey curettes 5 and 6; the other samples groups L1, L2, L3, L4 were radiated by diode laser using parameters of power 1,0 W; 1,2 W; 1,4 W; and 1,6 W respectively, 2 times for 10 seconds with 20 seconds intervals between each radiation in continuous mode. The results with relation to the increase of temperature in the interior of the root canal demonstrated that there was an increase of more than 5 degree Celsius. The results of the scanning electron microscope analysis of Control Group C demonstrated great irregularity and ridges on the root surface, with the presence of a dentine layer. Control Group C1 presented a similar aspect to Group L 1's, smoother and more homogeneous surface. Groups L2, L3, and L4 presented scratches alternating with smoother areas showing that fiber contacted the surface of the sample. The results reconfirmed the necessity of further studies using diode laser, with a beam of light emitted in an interrupted mode to improve the control of the

Evaluation of the morphological alteration of the root surface radiated with a diode laser; Avaliacao da alteracao morfologica da superficie cimentaria irradiada com laser de diodo

Energy Technology Data Exchange (ETDEWEB)

Gulin, Mauricio

2003-07-01

The diode laser has been studied for periodontal therapy, as much for removal of calculus as for microbial reduction of periodontal pockets, as well as the visible analgesic effects and biomodulation capacity. For this reason the purpose of this study was to evaluate the morphological alteration of the root surface after radiation with the diode laser, 808 nm through analysis by scanning electron microscopy (SEM). Besides this, to verify the temperature variations caused during the radiation, a thermometer put into the dentinal wall of the root canal was used. In all, 18 teeth were used, 15 of which for the SEM study, and the other 3 were used to temperature variation analysis. The 25 samples were scraped on the root surface and planed with manual instruments. The other 5 were not subjected to any type of treatment. This, 6 groups of 5 samples each were formed. Control Group C whose samples had not received any treatment; Control Group C 1 was only scraped and polished conventionally with Hu-Friedy Gracey curettes 5 and 6; the other samples groups L1, L2, L3, L4 were radiated by diode laser using parameters of power 1,0 W; 1,2 W; 1,4 W; and 1,6 W respectively, 2 times for 10 seconds with 20 seconds intervals between each radiation in continuous mode. The results with relation to the increase of temperature in the interior of the root canal demonstrated that there was an increase of more than 5 degree Celsius. The results of the scanning electron microscope analysis of Control Group C demonstrated great irregularity and ridges on the root surface, with the presence of a dentine layer. Control Group C1 presented a similar aspect to Group L 1's, smoother and more homogeneous surface. Groups L2, L3, and L4 presented scratches alternating with smoother areas showing that fiber contacted the surface of the sample. The results reconfirmed the necessity of further studies using diode laser, with a beam of light emitted in an interrupted mode to improve the control of

Smooth polishing of femtosecond laser induced craters on cemented carbide by ultrasonic vibration method

Science.gov (United States)

Wang, H. P.; Guan, Y. C.; Zheng, H. Y.

2017-12-01

Rough surface features induced by laser irradiation have been a challenging for the fabrication of micro/nano scale features. In this work, we propose hybrid ultrasonic vibration polishing method to improve surface quality of microcraters produced by femtosecond laser irradiation on cemented carbide. The laser caused rough surfaces are significantly smoothened after ultrasonic vibration polishing due to the strong collision effect of diamond particles on the surfaces. 3D morphology, SEM and AFM analysis has been conducted to characterize surface morphology and topography. Results indicate that the minimal surface roughness of Ra 7.60 nm has been achieved on the polished surfaces. The fabrication of microcraters with smooth surfaces is applicable to molding process for mass production of micro-optical components.

Morphological, chemical and structural characterisation of deciduous enamel: SEM, EDS, XRD, FTIR and XPS analysis.

Science.gov (United States)

Zamudio-Ortega, C M; Contreras-Bulnes, R; Scougall-Vilchis, R J; Morales-Luckie, R A; Olea-Mejía, O F; Rodríguez-Vilchis, L E

2014-09-01

The purpose of this study was to characterise the enamel surface of sound deciduous teeth in terms of morphology, chemical composition, structure and crystalline phases. The enamel of 30 human deciduous teeth was examined by: Scanning Electron Microscopy (SEM), Energy Dispersive X-Ray Spectroscopy (EDS), X-ray Powder Diffraction (XRD), Fourier Transform Infrared Spectroscopy (FTIR), and X-ray Photoelectron Spectroscopy (XPS). Chemical differences between incisors and canines were statistically evaluated using the Mann-Whitney U test (p ≤ 0.05). Three enamel patterns were observed by SEM: 'mostly smooth with some groves', 'abundant microporosities' and 'exposed prisms'. The average Ca/P molar ratios were 1.37 and 1.03 by EDS and XPS, respectively. The crystallite size determined by XRD was 210.82 ± 16.78 Å. The mean ratio between Ca bonded to phosphate and Ca bonded to hydroxyl was approximately 10:1. The enamel of sound deciduous teeth showed two main patterns: 'mostly smooth with some groves' and 'abundant microporosities'. 'Exposed prisms' was a secondary pattern. There were slight variations among the Ca/P molar ratios found by EDS and XPS, suggesting differences in the mineral content from the enamel surface to the interior. The crystalline phases found in enamel were hydroxyapatite and carbonate apatite, with major type B than type A carbonate incorporation.

Laser ablation of Au-CuO core-shell nanocomposite in water for optoelectronic devices

Science.gov (United States)

Ismail, Raid A.; Abdul-Hamed, Ryam S.

2017-12-01

Core-shell gold-copper oxide Au-CuO nanocomposites were synthesized using laser ablation of CuO target in colloidal solution of Au nanoparticles (NPs). The effect of laser fluence on the structural, morphological, electrical, and optical properties of Au-CuO nanocomposites was investigated using x-ray diffraction (XRD), atomic force microscope (AFM), scanning electron microscope (SEM), transmission electron microscope (TEM), photoluminescence (PL), Fourier transformed infrared spectroscopy (FTIR), Hall measurement, and UV-vis spectroscopy. X-ray diffraction results confirm the formation of polycrystalline Au-CuO NPs with monoclinic structure. The optical energy gap for CuO was 4 eV and for the Au-CuO core-shell nanocomposites was found to be in the range of 3.4-3.7 eV. SEM and TEM investigations revealed that the structure and morphology of Au-CuO core-shell nanocomposites were strongly depending on the laser fluence. A formation of Au-CuO nanospheres and platelets structures was observed. The photoluminescence data showed an emission of broad visible peaks between 407 and 420 nm. The effect of laser fluence on the dark and illuminated I-V characteristics of Au-CuO/n-Si heterojunction photodetectors was investigated and analyzed. The experimental data demonstrated that the photodetector prepared at optimum laser fluence exhibited photosensitivity of 0.6 AW-1 at 800 nm.

Phase structures and morphologies of tempered CA6NM stainless steel welded by hybrid laser-arc process

Energy Technology Data Exchange (ETDEWEB)

Mirakhorli, F., E-mail: Fatemeh.mirakhorli.1@ens.etsmtl.ca [École de Technologie Supérieure, Montréal, Québec H3C 1K3 (Canada); National Research Council Canada – Aerospace, Montréal, Québec H3T 2B2 (Canada); Cao, X., E-mail: Xinjin.cao@cnrc-nrc.gc.ca [National Research Council Canada – Aerospace, Montréal, Québec H3T 2B2 (Canada); Pham, X-T., E-mail: Tan.pham@etsmtl.ca [École de Technologie Supérieure, Montréal, Québec H3C 1K3 (Canada); Wanjara, P., E-mail: Priti.wanjara@cnrc-nrc.gc.ca [National Research Council Canada – Aerospace, Montréal, Québec H3T 2B2 (Canada); Fihey, J.L., E-mail: jean-luc.fihey@etsmtl.ca [École de Technologie Supérieure, Montréal, Québec H3C 1K3 (Canada)

2017-01-15

The post-weld tempered microstructure of hybrid laser-arc welded CA6NM, a cast low carbon martensitic stainless steel, was investigated. The microstructural evolutions from the fusion zone to the base metal were characterized in detail using optical microscopy, scanning electron microscopy (SEM), electron backscatter diffraction (EBSD), X-ray diffraction (XRD) and microhardness techniques. The fusion zone, in its post-weld tempered condition, consisted of tempered lath martensite, residual delta-ferrite with various morphologies, reversed austenite and chromium carbides. The reversed austenite, which can be detected through both EBSD and XRD techniques, was found to be finely dispersed along the martensite lath boundaries, particularly at triple junctions. Based on the EBSD analysis, the orientation relationship between the reversed austenite and the adjacent martensite laths seemed to follow the Kurdjumov-Sachs (K-S) model. The results also revealed the presence of the reversed austenite in the different regions of the heat affected zone after post-weld tempering. The microindentation hardness distribution was measured, and correlated to the evolution of the corresponding microstructure across the welds. - Highlights: •The EBSD analysis was performed on hybrid laser-arc welded CA6NM. •The FZ consisted of tempered lath martensite, reversed austenite, carbides and δ ferrite after tempering. •The reversed γ was formed along the α′ lath boundaries, particularly at triple junctions.

Surface morphology study on chromium oxide growth on Cr films by Nd-YAG laser oxidation process

International Nuclear Information System (INIS)

Dong Qizhi; Hu Jiandong; Guo Zuoxing; Lian Jianshe; Chen Jiwei; Chen Bo

2002-01-01

Grain sized (60-100 nm) Cr 2 O 3 thin films were prepared on Cr thin film surfaces by Nd-YAG laser photothermal oxidation process. Surface morphology study showed crack-free short plateau-like oxide films formed. Increase of dislocation density after pulsed laser irradiation was found. Thin film external surfaces, grain boundaries and dislocations are main paths of laser surface oxidation. Pinning and sealing of grain boundary was the reason that deeper oxidation did not produce. Grain growth and agglomeration of Cr sub-layer yielded tensile stress on the surface Cr 2 O 3 thin film. It was the reason that short plateau-like surface morphology formed and cracks appeared sometimes. In oxygen annealing at 700 deg. C, grain boundaries were considered not to be pinned at the surface, mixture diffusion was main mechanism in growth of oxide. Compression stress development in whole film led to extrusion of grains that was the reason that multiple appearances such as pyramid-like and nutshell-like morphology formed

Attachment and proliferation of human osteoblast-like cells (MG-63) on laser-ablated titanium implant material

Energy Technology Data Exchange (ETDEWEB)

Györgyey, Ágnes; Ungvári, Krisztina [Department of Oral Biology and Experimental Dental Research, Faculty of Dentistry, University of Szeged, H-6720 Szeged (Hungary); Kecskeméti, Gabriella; Kopniczky, Judit [Department of Optics and Quantum Electronics, Faculty of Science and Informatics, University of Szeged, H-6720 Szeged (Hungary); Hopp, Béla [Research Group on Laser Physics, Hungarian Academy of Sciences and University of Szeged, H-6720 Szeged (Hungary); Oszkó, Albert [Department of Physical Chemistry and Materials Science, Faculty of Science and Informatics, University of Szeged, H-6720 Szeged (Hungary); Pelsöczi, István; Rakonczay, Zoltán [Department of Oral Biology and Experimental Dental Research, Faculty of Dentistry, University of Szeged, H-6720 Szeged (Hungary); Nagy, Katalin [Department of Oral Surgery, Faculty of Dentistry, University of Szeged, H-6720 Szeged (Hungary); Turzó, Kinga, E-mail: kturzo@yahoo.com [Department of Oral Biology and Experimental Dental Research, Faculty of Dentistry, University of Szeged, H-6720 Szeged (Hungary)

2013-10-15

Demand is increasing for shortening the long (3–6 months) osseointegration period to rehabilitate patients' damaged chewing apparatus in as short a time as possible. For dental implants, as for biomaterials in general, the bio- and osseointegration processes can be controlled at molecular and cellular levels by modification of the implant surface. One of the most promising of such surface modifications is laser ablation, as demonstrated by our previous results [46]. Commercially pure (CP4) sand-blasted, acid-etched titanium disks (Denti® System Ltd., Hungary) were irradiated with a KrF excimer laser (248 nm, fluence 0.4 J/cm{sup 2}, FWHM 18 ns, 2000 pulses), or with a Nd:YAG laser (532 nm, 1.3 J/cm{sup 2}, 10 ns, 200 pulses) then examined by SEM, AFM, and XPS. In vitro attachment (24 h) and proliferation (72 h) of MG-63 osteoblast cells were investigated via dimethylthiazol-diphenyl tetrazolium bromide (MTT), alamarBlue (AB) assays alkaline phosphatase quantification (ALP) and SEM. SEM and AFM revealed significant changes in morphology and roughness. XPS confirmed the presence of TiO{sub 2} on each sample; after Nd:YAG treatment a reduced state of Ti (Ti{sup 3+}) was also observed. MTT, AB and ALP measurements detected an increase in the number of cells between the 24- and 72 hour observations; however, laser treatment did not affect cell attachment and proliferation significantly. - Highlights: • CP4 titanium implant surfaces were modified with Nd:YAG and KrF excimer laser. • SEM and AFM revealed significant changes in morphology and roughness. • XPS confirmed the presence of TiO{sub 2} on each sample; after Nd:YAG treatment a reduced state of Ti (Ti{sup 3+}) was found. • Cell proliferation experiments detected an increased number of MG-63 cells between the 24 h and 72 h observations. • Laser treatments neither disturbed, nor enhanced MG-63 cell attachment and proliferation significantly.

Attachment and proliferation of human osteoblast-like cells (MG-63) on laser-ablated titanium implant material

International Nuclear Information System (INIS)

Györgyey, Ágnes; Ungvári, Krisztina; Kecskeméti, Gabriella; Kopniczky, Judit; Hopp, Béla; Oszkó, Albert; Pelsöczi, István; Rakonczay, Zoltán; Nagy, Katalin; Turzó, Kinga

2013-01-01

Demand is increasing for shortening the long (3–6 months) osseointegration period to rehabilitate patients' damaged chewing apparatus in as short a time as possible. For dental implants, as for biomaterials in general, the bio- and osseointegration processes can be controlled at molecular and cellular levels by modification of the implant surface. One of the most promising of such surface modifications is laser ablation, as demonstrated by our previous results [46]. Commercially pure (CP4) sand-blasted, acid-etched titanium disks (Denti® System Ltd., Hungary) were irradiated with a KrF excimer laser (248 nm, fluence 0.4 J/cm 2 , FWHM 18 ns, 2000 pulses), or with a Nd:YAG laser (532 nm, 1.3 J/cm 2 , 10 ns, 200 pulses) then examined by SEM, AFM, and XPS. In vitro attachment (24 h) and proliferation (72 h) of MG-63 osteoblast cells were investigated via dimethylthiazol-diphenyl tetrazolium bromide (MTT), alamarBlue (AB) assays alkaline phosphatase quantification (ALP) and SEM. SEM and AFM revealed significant changes in morphology and roughness. XPS confirmed the presence of TiO 2 on each sample; after Nd:YAG treatment a reduced state of Ti (Ti 3+ ) was also observed. MTT, AB and ALP measurements detected an increase in the number of cells between the 24- and 72 hour observations; however, laser treatment did not affect cell attachment and proliferation significantly. - Highlights: • CP4 titanium implant surfaces were modified with Nd:YAG and KrF excimer laser. • SEM and AFM revealed significant changes in morphology and roughness. • XPS confirmed the presence of TiO 2 on each sample; after Nd:YAG treatment a reduced state of Ti (Ti 3+ ) was found. • Cell proliferation experiments detected an increased number of MG-63 cells between the 24 h and 72 h observations. • Laser treatments neither disturbed, nor enhanced MG-63 cell attachment and proliferation significantly

Structure and morphologies of ZnO nanoparticles synthesized by pulsed laser ablation in liquid: Effects of temperature and energy fluence

Energy Technology Data Exchange (ETDEWEB)

Guillén, G. García; Palma, M.I. Mendivil [Universidad Autónoma de Nuevo León, Facultad de Ingeniería Mecánica y Eléctrica, San Nicolás de los Garza, Nuevo León 66455 (Mexico); Krishnan, B. [Universidad Autónoma de Nuevo León, Facultad de Ingeniería Mecánica y Eléctrica, San Nicolás de los Garza, Nuevo León 66455 (Mexico); Universidad Autónoma de Nuevo León – Centro de Innovación, Investigación y Desarrollo de Ingeniería y Tecnología, Apodaca, Nuevo León 66600 (Mexico); Avellaneda, D.; Castillo, G.A.; Roy, T.K. Das [Universidad Autónoma de Nuevo León, Facultad de Ingeniería Mecánica y Eléctrica, San Nicolás de los Garza, Nuevo León 66455 (Mexico); and others

2015-07-15

Zinc oxide nanoparticles were prepared by pulsed laser ablation of a zinc metal target at different water temperatures (room temperature, 50, 70 and 90 °C). Ablation was carried out using 532 nm output from a pulsed (10 ns, 10 Hz) Nd:YAG laser at three different laser fluence. Analysis of the morphology, crystalline phase, elemental composition, optical and luminescent properties were done using Transmission Electron Microscopy (TEM), X-Ray Photoelectron Spectroscopy (XPS), UV–visible absorption spectroscopy and photoluminescence spectroscopy. TEM analysis showed that a change in temperature resulted in ZnO and Zn(OH){sub 2} nanoparticles with different sizes and morphologies. XPS results confirmed the compositions and chemical states of these nanoparticles. These zinc nanomaterials showed emission in the ultraviolet (UV) and blue regions. The results of this work demonstrated that by varying the liquid medium temperature, the structure, composition, morphology and optical properties of the nanomaterials could be modified during pulsed laser ablation in liquid. - Graphical abstract: Display Omitted - Highlights: • Zinc nanomaterial colloids were synthesized by PLAL. • Effects of laser fluence and the distilled water temperature were analyzed. • The final structure varied with the distilled water temperature and laser fluence. • The morphology was dependent on the distilled water temperature and laser fluence. • Zinc nanocolloids showed emission in the UV and blue region.

Structure and morphologies of ZnO nanoparticles synthesized by pulsed laser ablation in liquid: Effects of temperature and energy fluence

International Nuclear Information System (INIS)

Guillén, G. García; Palma, M.I. Mendivil; Krishnan, B.; Avellaneda, D.; Castillo, G.A.; Roy, T.K. Das

2015-01-01

Zinc oxide nanoparticles were prepared by pulsed laser ablation of a zinc metal target at different water temperatures (room temperature, 50, 70 and 90 °C). Ablation was carried out using 532 nm output from a pulsed (10 ns, 10 Hz) Nd:YAG laser at three different laser fluence. Analysis of the morphology, crystalline phase, elemental composition, optical and luminescent properties were done using Transmission Electron Microscopy (TEM), X-Ray Photoelectron Spectroscopy (XPS), UV–visible absorption spectroscopy and photoluminescence spectroscopy. TEM analysis showed that a change in temperature resulted in ZnO and Zn(OH) 2 nanoparticles with different sizes and morphologies. XPS results confirmed the compositions and chemical states of these nanoparticles. These zinc nanomaterials showed emission in the ultraviolet (UV) and blue regions. The results of this work demonstrated that by varying the liquid medium temperature, the structure, composition, morphology and optical properties of the nanomaterials could be modified during pulsed laser ablation in liquid. - Graphical abstract: Display Omitted - Highlights: • Zinc nanomaterial colloids were synthesized by PLAL. • Effects of laser fluence and the distilled water temperature were analyzed. • The final structure varied with the distilled water temperature and laser fluence. • The morphology was dependent on the distilled water temperature and laser fluence. • Zinc nanocolloids showed emission in the UV and blue region

Laser cutting: influence on morphological and physicochemical properties of polyhydroxybutyrate.

Science.gov (United States)

Lootz, D; Behrend, D; Kramer, S; Freier, T; Haubold, A; Benkiesser, G; Schmitz, K P; Becher, B

2001-09-01

Polyhydroxybutyrate (PHB) is a biocompatible and resorbable implant material. For these reasons, it has been used for the fabrication of temporary stents, bone plates, nails and screws (Peng et al. Biomaterials 1996;17:685). In some cases, the brittle mechanical properties of PHB homopolymer limit its application. A typical plasticizer, triethylcitrate (TEC), was used to overcome such limitations by making the material more pliable. In the past few years, CO2-laser cutting of PHB was used in the manufacturing of small medical devices such as stents. Embrittlement of plasticized PHB tubes has been observed, after laser machining. Consequently, the physicochemical and morphological properties of laser-processed surfaces and cut edges of plasticized polymer samples were examined to determine the extent of changes in polymer properties as a result of laser machining. These studies included determination of the depth of the laser-induced heat affected zone by polariscopy of thin polymer sections. Molecular weight changes and changes in the TEC content as a function of distance from the laser-cut edge were determined. In a preliminary test, the cellular response to the processed material was investigated by cell culture study of L929 mouse fibroblasts on laser-machined surfaces. The heat-affected zone was readily classified into four different regions with a total depth of about 60 to 100 microm (Klamp, Master Thesis, University of Rostock, 1998). These results correspond well with the chemical analysis and molecular weight measurements. Furthermore, it was found that cells grew preferentially on the laser-machined area. These findings have significant implications for the manufacture of medical implants from PHB by laser machining.

Analysis of Shear Bond Strength and Morphology of Er:YAG Laser-Recycled Ceramic Orthodontic Brackets.

Science.gov (United States)

Han, Ruo-qiao; Yang, Kai; Ji, Ling-fei; Ling, Chen

2016-01-01

The aim of this study was to compare the recycling of deboned ceramic brackets via an Er:YAG laser or via the traditional chairside processing methods of flaming and sandblasting; shear bond strength and morphological changes were evaluated in recycled brackets versus new brackets. 3M Clarity Self-Ligating Ceramic Brackets with a microcrystalline base were divided into groups subjected to flaming, sandblasting, or exposure to an Er:YAG laser. New ceramic brackets served as a control group. Shear bond strengths were determined with an Electroforce test machine and tested for statistical significance through analysis of variance. Morphological examinations of the recycled ceramic bracket bases were conducted with scanning electron microscopy and confocal laser scanning microscopy. Residue on the bracket base was analyzed with Raman spectroscopy. Faded, dark adhesive was left on recycled bracket bases processed via flaming. Adhesive was thoroughly removed by both sandblasting and exposure to an Er:YAG laser. Compared with new brackets, shear bond strength was lower after sandblasting (p bracket. Er:YAG lasers effectively remove adhesive from the bases of ceramic brackets without damaging them; thus, this method may be preferred over other recycling methods.

Morphology of IR and UV Laser-induced Structural Changes on Silicon Surfaces

International Nuclear Information System (INIS)

Jimenez-Jarquin, J.; Haro-Poniatowski, E.; Fernandez-Guasti, M.; Hernandez-Pozos, J.L.

2005-01-01

Using scanning electronic microscopy, we analyze the structural changes induced in silicon (100) wafers by focused IR (1064 nm) and UV (355 nm) nanosecond laser pulses. The experiments were performed in the laser ablation regime. When a silicon surface is irradiated by laser pulses in an O2 atmosphere conical microstructures are obtained. The changes in silicon surface morphology depend both on the incident radiation wavelength and the environmental atmosphere. We have patterned Si surfaces with a single focused laser spot and, in doing the experiments with IR or UV this reveals significant differences in the initial surface cracking and pattern formation, however the final result consist of an array of microcones when the experiment is carried out in oxygen. We employ a random scanning technique to irradiate silicon surfaces over large areas. In this form we have obtained large patterned areas

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

Science.gov (United States)

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

2014-05-01

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

Laser cleaning of pulsed laser deposited rhodium films for fusion diagnostic mirrors

International Nuclear Information System (INIS)

Uccello, A.; Maffini, A.; Dellasega, D.; Passoni, M.

2013-01-01

Highlights: ► Pulsed laser deposition is exploited to produce Rh films for first mirrors. ► Pulsed laser deposition is exploited to produce tokamak-like C contaminants. ► Rh laser damage threshold has been evaluated for infrared pulses. ► Laser cleaning of C contaminated Rh films gives promising results. -- Abstract: In this paper an experimental investigation on the laser cleaning process of rhodium films, potentially candidates to be used as tokamak first mirrors (FMs), from redeposited carbon contaminants is presented. A relevant issue that lowers mirror's performance during tokamak operations is the redeposition of sputtered material from the first wall on their surface. Among all the possible techniques, laser cleaning, in which a train of laser pulses is launched to the surface that has to be treated, is a method to potentially mitigate this problem. The same laser system (Q-switched Nd:YAG laser with a fundamental wavelength of 1064-nm and 7-ns pulses) has been employed with three aims: (i) production by pulsed laser deposition (PLD) of Rh film mirrors, (ii) production by PLD of C deposits with controlled morphology, and (iii) investigation of the laser cleaning method onto C contaminated Rh samples. The evaluation of Rh films laser damage threshold, as a function of fluence and number of pulses, is discussed. Then, the C/Rh films have been cleaned by the laser beam. The exposed zones have been characterized by visual inspection and scanning electron microscopy (SEM), showing promising results

Skeletal stem cell and bone implant interactions are enhanced by LASER titanium modification

Energy Technology Data Exchange (ETDEWEB)

Sisti, Karin E., E-mail: karinellensisti@gmail.com [Bone and Joint Research Group, Centre for Human Development, Stem Cells and Regeneration, Institute of Developmental Sciences, University of Southampton, Southampton SO16 6YD (United Kingdom); Biomaterials Group, Institute of Chemistry, São Paulo State University (UNESP), Box 355, Araraquara (Brazil); Federal University of Mato Grosso do Sul (UFMS), Campo Grande (Brazil); Andrés, María C. de; Johnston, David [Bone and Joint Research Group, Centre for Human Development, Stem Cells and Regeneration, Institute of Developmental Sciences, University of Southampton, Southampton SO16 6YD (United Kingdom); Almeida-Filho, Edson; Guastaldi, Antonio C. [Biomaterials Group, Institute of Chemistry, São Paulo State University (UNESP), Box 355, Araraquara (Brazil); Oreffo, Richard O.C. [Bone and Joint Research Group, Centre for Human Development, Stem Cells and Regeneration, Institute of Developmental Sciences, University of Southampton, Southampton SO16 6YD (United Kingdom)

2016-05-06

Purpose: To evaluate the osteo-regenerative potential of Titanium (Ti) modified by Light Amplification by Stimulated Emission of Radiation (LASER) beam (Yb-YAG) upon culture with human Skeletal Stem Cells (hSSCs{sup 1}). Methods: Human skeletal cell populations were isolated from the bone marrow of haematologically normal patients undergoing primary total hip replacement following appropriate consent. STRO-1{sup +} hSSC{sup 1} function was examined for 10 days across four groups using Ti discs: i) machined Ti surface group in basal media (Mb{sup 2}), ii) machined Ti surface group in osteogenic media (Mo{sup 3}), iii) LASER-modified Ti group in basal media (Lb{sup 4}) and, iv) LASER-modified Ti group in osteogenic media (Lo{sup 5}). Molecular analysis and qRT-PCR as well as functional analysis including biochemistry (DNA, Alkaline Phosphatase (ALP{sup 6}) specific activity), live/dead immunostaining (Cell Tracker Green (CTG{sup 7})/Ethidium Homodimer-1 (EH-1{sup 8})), and fluorescence staining (for vinculin and phalloidin) were undertaken. Inverted, confocal and Scanning Electron Microscopy (SEM) approaches were used to characterise cell adherence, proliferation, and phenotype. Results: Enhanced cell spreading and morphological rearrangement, including focal adhesions were observed following culture of hSSCs{sup 1} on LASER surfaces in both basal and osteogenic conditions. Biochemical analysis demonstrated enhanced ALP{sup 6} specific activity on the hSSCs{sup 1}-seeded on LASER-modified surface in basal culture media. Molecular analysis demonstrated enhanced ALP{sup 6} and osteopontin expression on titanium LASER treated surfaces in basal conditions. SEM, inverted microscopy and confocal laser scanning microscopy confirmed extensive proliferation and migration of human bone marrow stromal cells on all surfaces evaluated. Conclusions: LASER-modified Ti surfaces modify the behaviour of hSSCs.{sup 1} In particular, SSC{sup 1} adhesion, osteogenic gene expression, cell

Study on the role of laser surface irradiation on damage and decohesion of Al/epoxy joints

KAUST Repository

Alfano, Marco; Lubineau, Gilles; Furgiuele, Franco M.; Paulino, Glá ucio Hermogenes

2012-01-01

In this work we investigate the effect of laser irradiation on the bond toughness of aluminum/epoxy bonded joints. The evolution of substrate surface morphology and wettability, for various sets of laser process parameters (i.e. laser power, line spacing, scan speed), was investigated by means of Scanning Electron Microscopy (SEM) and contact angle measurements. A proper combination of power, line spacing and scan speed was then selected and adhesive bonded Al/epoxy T-peel joints were prepared and tested. For comparison, similar samples were produced using substrates with classical grit blasting surface treatment. Finally, post-failure SEM analyses of fracture surfaces were performed, and in order to typify the increase in bond toughness of the joints, finite element simulations were carried out using a potential based cohesive zone model of fracture. © 2012 Elsevier Ltd.

Study on the role of laser surface irradiation on damage and decohesion of Al/epoxy joints

KAUST Repository

Alfano, Marco

2012-12-01

In this work we investigate the effect of laser irradiation on the bond toughness of aluminum/epoxy bonded joints. The evolution of substrate surface morphology and wettability, for various sets of laser process parameters (i.e. laser power, line spacing, scan speed), was investigated by means of Scanning Electron Microscopy (SEM) and contact angle measurements. A proper combination of power, line spacing and scan speed was then selected and adhesive bonded Al/epoxy T-peel joints were prepared and tested. For comparison, similar samples were produced using substrates with classical grit blasting surface treatment. Finally, post-failure SEM analyses of fracture surfaces were performed, and in order to typify the increase in bond toughness of the joints, finite element simulations were carried out using a potential based cohesive zone model of fracture. © 2012 Elsevier Ltd.

Quantitative roughness characterization and 3D reconstruction of electrode surface using cyclic voltammetry and SEM image

Energy Technology Data Exchange (ETDEWEB)

Dhillon, Shweta; Kant, Rama, E-mail: rkant@chemistry.du.ac.in

2013-10-01

Area measurements from cyclic voltammetry (CV) and image from scanning electron microscopy (SEM) are used to characterize electrode statistical morphology, 3D surface reconstruction and its electroactivity. SEM images of single phased materials correspond to two-dimensional (2D) projections of 3D structures, leading to an incomplete characterization. Lack of third dimension information in SEM image is circumvented using equivalence between denoised SEM image and CV area measurements. This CV-SEM method can be used to estimate power spectral density (PSD), width, gradient, finite fractal nature of roughness and local morphology of the electrode. We show that the surface morphological statistical property like distribution function of gradient can be related to local electro-activity. Electrode surface gradient micrographs generated here can provide map of electro-activity sites. Finally, the densely and uniformly packed small gradient over the Pt-surface is the determining criterion for high intrinsic electrode activity.

Quantitative roughness characterization and 3D reconstruction of electrode surface using cyclic voltammetry and SEM image

International Nuclear Information System (INIS)

Dhillon, Shweta; Kant, Rama

2013-01-01

Area measurements from cyclic voltammetry (CV) and image from scanning electron microscopy (SEM) are used to characterize electrode statistical morphology, 3D surface reconstruction and its electroactivity. SEM images of single phased materials correspond to two-dimensional (2D) projections of 3D structures, leading to an incomplete characterization. Lack of third dimension information in SEM image is circumvented using equivalence between denoised SEM image and CV area measurements. This CV-SEM method can be used to estimate power spectral density (PSD), width, gradient, finite fractal nature of roughness and local morphology of the electrode. We show that the surface morphological statistical property like distribution function of gradient can be related to local electro-activity. Electrode surface gradient micrographs generated here can provide map of electro-activity sites. Finally, the densely and uniformly packed small gradient over the Pt-surface is the determining criterion for high intrinsic electrode activity.

Analysis of corneal endothelial cell density and morphology after laser in situ keratomileusis using two types of femtosecond lasers

Directory of Open Access Journals (Sweden)

Tomita M

2012-09-01

Full Text Available Minoru Tomita,1,2,* George O Waring IV,3,4 Miyuki Watabe,1,* 1Shinagawa LASIK Center, Chiyoda-ku, Tokyo, Japan; 2Department of Ophthalmology, Wenzhou Medical College, Wenzhou, China; 3Medical University of South Carolina, Storm Eye Institute, Charleston, SC, USA; 4Magill Laser Center, Charleston, SC, USA*These authors contributed equally to this studyPurpose: To compare two different femtosecond lasers used for flap creation during laser-assisted in situ keratomileusis (LASIK surgery in terms of their effects on the corneal endothelium.Methods: We performed LASIK surgery on 254 eyes of 131 patients using IntraLase FS60 (Abbott Medical Optics, Inc, Irvine, CA; IntraLase group and 254 eyes of 136 patients using Femto LDV (Ziemer Group AG, Port, Switzerland; LDV group for corneal flap creation. The mean cell density, coefficient of variation, and hexagonality of the corneal endothelial cells were determined and the results were statistically compared.Results: There were no statistically significant differences in the corneal morphology between pre and post LASIK results in each group, nor were there significant differences between the results of both groups at 3 months post LASIK.Conclusions: Both IntraLase FS60 and Ziemer Femto LDV are able to create flaps without significant adverse effects on the corneal endothelial morphology through 3 months after LASIK surgery.Keywords: LASIK, corneal endothelium, femtosecond laser, IntraLase FS60, Ziemer LDV

CdS thin films prepared by continuous wave Nd:YAG laser

Science.gov (United States)

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

1995-08-01

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

Structural and morphological transformations of TiO2 nanotube arrays induced by excimer laser treatment

International Nuclear Information System (INIS)

Hsu, Ming-Yi; Thang, Nguyen Van; Wang Chih; Leu Jihperng

2012-01-01

The structural and morphological transformations of TiO 2 nanotube arrays (TNAs) treated by excimer laser annealing (ELA) were investigated as a function of the laser fluence using parallel and tilted modes. Results showed that the crystallinity of the ELA-treated TNAs reached only about 50% relative to that of TNAs treated by furnace anneal at 400 °C for 1 h. The phase transformation starts from the top surface of the TNAs with surface damage resulting from short penetration depth and limited one-dimensional heat transport from the surface to the bottom under extremely short pulse duration (25 ns) of the excimer laser. When a tilted mode was used, the crystallinity of TNAs treated by ELA at 85° was increased to 90% relative to that by the furnace anneal. This can be attributed to the increased area of the laser energy interaction zone and better heat conduction to both ends of the TNAs. - Highlights: ► We examined the morphology and microstructure of TNAs treated by ELA. ► Crystallinity of parallel ELA-treated TNAs reached ∼50% of furnace anneal. ► Tilted ELA at 85o enhanced the degree of crystallization in TNAs to 90%.

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

Science.gov (United States)

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

2012-10-01

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

Nd:YAG laser annealing investigation of screen-printed CIGS layer on PET: Layer annealing method for photovoltaic cell fabrication process

KAUST Repository

Alsaggaf, Ahmed; Alarousu, Erkki; Boulfrad, Samir; Rothenberger, Alexander

2014-01-01

by heat treatment using a Nd:YAG laser. The structure and morphology of the heated thin films were studied. The characterization of the CIGS powder, ink, and film was done using TGA, SEM, FIB, EDS, and XRD. TGA analysis shows that the CIGS ink is drying

Effect of electric field distribution on the morphologies of laser-induced damage in hafnia-silica multilayer polarizers

International Nuclear Information System (INIS)

Genin, F.Y.; Stolz, C.J.; Reitter, T.; Kozlowski, M.R.; Bevis, R.P.; vonGunten, M.K.

1997-01-01

Hafnia-silica multilayer polarizers were deposited by e-beam evaporation onto BK7 glass substrates. The polarizers were designed to operate at 1064 nm at Brewster's angle (56 degree). They were tested with a 3-ns laser pulse at 45, 56, and 65 degree incidence angle in order to vary the electric field distribution in the multilayer, study their effects on damage morphology, and investigate possible advantages of off-use angle laser conditioning. Morphology of the laser-induced damage was characterized by optical and scanning electron microscopy. Four distinct damage morphologies (pit, flat bottom pit, scald, outer layer delamination) were observed; they depend strongly on incident angle of the laser beam. Massive delamination observed at 45 and 56 degree incidence, did not occur at 65 degree; instead, large and deep pits were found at 65 degree. Electric field distribution, temperature rise, and change in stress in the multilayer were calculated to attempt to better understand the relation between damage morphology, electric field peak locations, and maximum thermal stress gradients. The calculations showed a twofold increase in stress change in the hafnia top layers depending on incident angle. Stress gradient in the first hafnia-silica interface was found to be highest for 45, 56, and 65 degree, respectively. Finally, the maximum stress was deeper in the multilayer at 65 degree. Although the limitations of such simple thermal mechanical model are obvious, the results can explain that outer layer delamination is more likely at 45 and 56 degree than 65 degree and that damage sites are expected to be deeper at 65 degree

Ejection of matrix-polymer clusters in matrix-assisted laser evaporation: Experimental observations

International Nuclear Information System (INIS)

Sellinger, Aaron T; Leveugle, Elodie; Gogick, Kristy; Peman, Guillaume; Zhigilei, Leonid V; Fitz-Gerald, James M

2007-01-01

The morphology of polymer films deposited with the matrix-assisted pulsed laser evaporation (MAPLE) technique is explored for various target compositions and laser fluences. Composite targets of 1 to 5 wt.% poly(methyl methacrylate), PMMA, dissolved in a volatile matrix material, toluene, were ablated using an excimer laser at fluences ranging from 0.045 J/cm 2 to 0.75 J/cm 2 . Films were deposited on Si substrates at room temperature in a dynamic 100 mTorr Ar atmosphere. Scanning electron microscopy (SEM) imaging revealed that the morphology of the deposited films varied significantly with both laser fluence and PMMA concentration. The morphologies of large deposited particles were similar to that of deflated ''balloons''. It is speculated that during ablation of the frozen target, clusters comprised of both polymer and solvent ranging from 100 nm to 10 μm in size are ejected and deposited onto the substrate. The solvent begins to evaporate from the clusters during flight from the target, but does not completely evaporate until deposited on the room temperature substrate. The dynamics of the toluene evaporation may lead to the formation of the deflated structures. This explanation is supported by the observation of stable polymer-matrix droplets ejected in molecular dynamics simulations of MAPLE

In Vitro Study of Dentin Hypersensitivity Treated by 980-nm Diode Laser.

Science.gov (United States)

Liu, Ying; Gao, Jie; Gao, Yan; Xu, Shuaimei; Zhan, Xueling; Wu, Buling

2013-01-01

To investigate the ultrastructural changes of dentin irradiated with 980-nm diode laser under different parameters and to observe the morphological alterations of odontoblasts and pulp tissue to determine the safety parameters of 980-nm diode laser in the treatment of dentin hypersensitivity (DH). Twenty extracted human third molars were selected to prepare dentin discs. Each dentin disc was divided into four areas and was irradiated by 980-nm diode laser under different parameters: Group A: control group, 0 J/cm(2); Group B: 2 W/CW (continuous mode), 166 J/cm(2); Group C: 3W/CW, 250 J/cm(2); and Group D: 4W/CW, 333 J/cm(2). Ten additional extracted human third molars were selected to prepare dentin discs. Each dentin disc was divided into two areas and was irradiated by 980-nm diode laser: Group E: control group, 0 J/cm(2); and Group F: 2.0 W/CW, 166 J/cm(2). The morphological alterations of the dentin surfaces and odontoblasts were examined with scanning electron microscopy (SEM), and the morphological alterations of the dental pulp tissue irradiated by laser were observed with an upright microscope. The study demonstrated that dentinal tubules can be entirely blocked after irradiation by 980-nm diode laser, regardless of the parameter setting. Diode laser with settings of 2.0 W and 980-nm sealed exposed dentin tubules effectively, and no significant morphological alterations of the pulp and odontoblasts were observed after irradiation. Irradiation with 980-nm diode laser could be effective for routine clinical treatment of DH, and 2.0W/CW (166 J/cm(2)) was a suitable energy parameter due to its rapid sealing of the exposed dentin tubules and its safety to the odontoblasts and pulp tissue.

In Vitro Study of Dentin Hypersensitivity Treated by 980-nm Diode Laser

Science.gov (United States)

Liu, Ying; Gao, Jie; Gao, Yan; XU, Shuaimei; Zhan, Xueling; Wu, Buling

2013-01-01

Introduction: To investigate the ultrastructural changes of dentin irradiated with 980-nm diode laser under different parameters and to observe the morphological alterations of odontoblasts and pulp tissue to determine the safety parameters of 980-nm diode laser in the treatment of dentin hypersensitivity (DH). Methods: Twenty extracted human third molars were selected to prepare dentin discs. Each dentin disc was divided into four areas and was irradiated by 980-nm diode laser under different parameters: Group A: control group, 0 J/cm2; Group B: 2 W/CW (continuous mode), 166 J/cm2; Group C: 3W/CW, 250 J/cm2; and Group D: 4W/CW, 333 J/cm2. Ten additional extracted human third molars were selected to prepare dentin discs. Each dentin disc was divided into two areas and was irradiated by 980-nm diode laser: Group E: control group, 0 J/cm2; and Group F: 2.0 W/CW, 166 J/cm2. The morphological alterations of the dentin surfaces and odontoblasts were examined with scanning electron microscopy (SEM), and the morphological alterations of the dental pulp tissue irradiated by laser were observed with an upright microscope. Results: The study demonstrated that dentinal tubules can be entirely blocked after irradiation by 980-nm diode laser, regardless of the parameter setting. Diode laser with settings of 2.0 W and 980-nm sealed exposed dentin tubules effectively, and no significant morphological alterations of the pulp and odontoblasts were observed after irradiation. Conclusions: Irradiation with 980-nm diode laser could be effective for routine clinical treatment of DH, and 2.0W/CW (166 J/cm2) was a suitable energy parameter due to its rapid sealing of the exposed dentin tubules and its safety to the odontoblasts and pulp tissue. PMID:25606318

IR and UV laser-induced morphological changes in silicon surface under oxygen atmosphere

Energy Technology Data Exchange (ETDEWEB)

Jimenez-Jarquin, J.; Fernandez-Guasti, M.; Haro-Poniatowski, E.; Hernandez-Pozos, J.L. [Laboratorio de Optica Cuantica, Departamento de Fisica, Universidad Autonoma Metropolitana-Iztapalapa, Av. San Rafael Atlixco No. 186, Col. Vicentina, C.P. 09340, Mexico D.F. (Mexico)

2005-08-01

We irradiated silicon (100) wafers with IR (1064 nm) and UV (355 nm) nanosecond laser pulses with energy densities within the ablation regime and used scanning electron microscopy to analyze the morphological changes induced on the Si surface. The changes in the wafer morphology depend both on the incident radiation wavelength and the environmental atmosphere. We have patterned Si surfaces with a single focused laser spot and, in doing the experiments with IR or UV this reveals significant differences in the initial surface cracking and pattern formation, however if the experiment is carried out in O{sub 2} the final result is an array of microcones. We also employed a random scanning technique to irradiate the silicon wafer over large areas, in this case the microstructure patterns consist of a ''semi-ordered'' array of micron-sized cones. (copyright 2005 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

Morphologies of laser-induced damage in hafnia-silica multilayer mirror and polarizer coatings

International Nuclear Information System (INIS)

Genin, F.Y.; Stolz, C.J.

1996-08-01

Hafnium-silica multilayer mirrors and polarizers were deposited by e-beam evaporation onto BK7 glass substrates. The mirrors and polarizers were coated for operation at 1053 nm at 45 degree and at Brewster's angle (56 degree), respectively. They were tested with a single 3-ns laser pulse. Morphology of the laser-induced damage was characterized by optical and scanning electron microscopy. Four distinct damage morphologies were found: pits, flatbottom pits, scalds, and delaminates. The pits and flat bottom pits ( 2 ). The pits seemed to result from ejection of nodular defects by causing local enhancement of the electric field. Scalds and delaminates could be observed at higher fluences (above 13 J/cm 2 ) and seemed to result from the formation of plasmas on the surface. These damage types often originated at pits and were less than 300 μm diameter; their size increased almost linearly with fluence. Finally, effects of the damage on the beam (reflectivity degradation and phase modulations) were measured

The effect of powder composition on the morphology of in situ TiC composite coating deposited by Laser-Assisted Powder Deposition (LAPD)

International Nuclear Information System (INIS)

Emamian, Ali; Corbin, Stephen F.; Khajepour, Amir

2012-01-01

Highlights: ► The novel idea was to develop Fe-TiC containing high volume fraction of TiC. ► Increased TiC volume fraction enhanced clad hardness profile. ► Both, laser conditions and fed powder compositions affected the clad microstructure. ► Hardness and TiC volume fraction was maximized by control over melt pool composition. ► Hardness/TiC volume fraction was maximized by controlling of laser parameters. - Abstract: In this paper, the effect of powder composition on in situ TiC formation within an Fe-based matrix coating during laser cladding was studied. Different atomic ratios of C:Ti (45% and 55%) were selected in order to adjust the matrix from an Fe-Ti-based composition to an Fe-C-based one. Fe percentages of 70, 60, 50 and 10 wt% were explored to increase the volume fraction of TiC in the clad. Results showed that chemical composition affects the TiC morphology as well as the TiC distribution and hardness profile in the clad. By increasing the C:Ti ratio from 45 at% to 55 at%, the volume fraction of the formed TiC increases. A higher volume fraction of TiC in the clad resulted in increases clad hardness. SEM and EDS analyses were used to characterize the phases in the clad, while increasing the C ratio promoted the formation of excess graphite in the Fe matrix.

The effect of powder composition on the morphology of in situ TiC composite coating deposited by Laser-Assisted Powder Deposition (LAPD)

Energy Technology Data Exchange (ETDEWEB)

Emamian, Ali, E-mail: aemamian@uwaterloo.ca [Research Associate and Postdoctoral fellow in the Department of Mechanics and Mechatronics, University of Waterloo, 200 University West, Waterloo, N2L 4 3G1 (Canada); Corbin, Stephen F. [Professor and Canada Research Chair in the Department of Civil and Resource Engineering, Dalhousie University, Halifax, Nova Scotia, P.O. Box 15000, B3H 5 4R2 (Canada); Khajepour, Amir [Professor and Canada Research Chair in the Department of Mechanical and Mechatronics Engineering, University of Waterloo, Waterloo (Canada)

2012-11-15

Highlights: Black-Right-Pointing-Pointer The novel idea was to develop Fe-TiC containing high volume fraction of TiC. Black-Right-Pointing-Pointer Increased TiC volume fraction enhanced clad hardness profile. Black-Right-Pointing-Pointer Both, laser conditions and fed powder compositions affected the clad microstructure. Black-Right-Pointing-Pointer Hardness and TiC volume fraction was maximized by control over melt pool composition. Black-Right-Pointing-Pointer Hardness/TiC volume fraction was maximized by controlling of laser parameters. - Abstract: In this paper, the effect of powder composition on in situ TiC formation within an Fe-based matrix coating during laser cladding was studied. Different atomic ratios of C:Ti (45% and 55%) were selected in order to adjust the matrix from an Fe-Ti-based composition to an Fe-C-based one. Fe percentages of 70, 60, 50 and 10 wt% were explored to increase the volume fraction of TiC in the clad. Results showed that chemical composition affects the TiC morphology as well as the TiC distribution and hardness profile in the clad. By increasing the C:Ti ratio from 45 at% to 55 at%, the volume fraction of the formed TiC increases. A higher volume fraction of TiC in the clad resulted in increases clad hardness. SEM and EDS analyses were used to characterize the phases in the clad, while increasing the C ratio promoted the formation of excess graphite in the Fe matrix.

Pulsed laser ablation of Germanium under vacuum and hydrogen environments at various fluences

Energy Technology Data Exchange (ETDEWEB)

Iqbal, Muhammad Hassan [Centre for Advanced Studies in Physics, Government College University, Lahore (Pakistan); Bashir, Shazia, E-mail: shaziabashir@gcu.edu.pk [Centre for Advanced Studies in Physics, Government College University, Lahore (Pakistan); Rafique, Muhammad Shahid [Department of Physics, University of Engineering and Technology, Lahore (Pakistan); Dawood, Asadullah; Akram, Mahreen; Mahmood, Khaliq; Hayat, Asma; Ahmad, Riaz; Hussain, Tousif [Centre for Advanced Studies in Physics, Government College University, Lahore (Pakistan); Mahmood, Arshad [National Institute of Laser and Optronics (NILOP), Islamabad (Pakistan)

2015-07-30

Highlights: • Germanium targets were exposed under vacuum and H{sub 2} environment by nanosecond laser pulses. • The effect of laser fluence and ambient environment has been investigated. • The surface morphology is investigated by SEM analysis. • Raman and FTIR Spectroscopy are performed to reveal structural modification. • Electrical conductivity is probed by four probe method. - Abstract: Laser fluence and ambient environment play a significant role for the formation and development of the micro/nano-structures on the laser irradiated targets. Single crystal (1 0 0) Germanium (Ge) has been ablated under two environments of vacuum (10{sup −3} Torr) and hydrogen (100 Torr) at various fluences ranging from 4.5 J cm{sup −2} to 6 J cm{sup −2}. For this purpose KrF Excimer laser with wavelength of 248 nm, pulse duration of 18 ns and repetition rate of 20 Hz has been employed. Surface morphology has been observed by Scanning Electron Microscope (SEM). Whereas, structural modification of irradiated targets was explored by Fourier Transform Infrared Spectroscopy (FTIR) and Raman spectroscopy. Electrical conductivity of the irradiated Ge is measured by four probe method. SEM analysis exhibits the formation of laser-induced periodic surface structures (LIPSS), cones and micro-bumps in both ambient environments (vacuum and hydrogen). The formation as well as development of these structures is strongly dependent upon the laser fluence and environmental conditions. The periodicity of LIPSS or ripples varies from 38 μm to 60 μm in case of vacuum whereas in case of hydrogen environment, the periodicity varies from 20 μm to 45 μm. The difference in number of ripples and periodicity as well as in shape and size of cones and bumps in vacuum and hydrogen is explained on the basis of confinement and shielding effect of plasma. FTIR spectroscopy reveals that no new bands are formed for laser ablated Ge under vacuum, whereas C−H stretching vibration band is

Influence of the incidence angle on the morphology of enamel and dentin under Er:YAG laser irradiation

International Nuclear Information System (INIS)

Junqueira Junior, Duilio Naves

2002-01-01

The purpose of this study is to make an in vitro evaluation, using scanning electron microscopy, of the influence of the laser beam irradiation angle on the enamel and dentin morphology. These tissues were both irradiated by Er:YAG Laser, with the same energy parameter. Twenty-four incisive bovine teeth were used, separated in eight groups, four of enamel, and four of dentin, with three specimens in each group. Each specimen was submitted to three laser applications, varying the incidence angle, between the laser and the tooth surface, at 90, 50 and 20 degrees. The applied frequency was 2 Hz, with 20 pulses in each application. The KaVo Key Laser 3 was employed, wavelength at 2940 nm, adjustable energy from 40 to 600 mJ and repetition rate from 1 to 25 Hz. The groups were distributed according to the energy parameter as follows - enamel: 250 mJ; 300 mJ; 350 mJ and 400 mJ; dentin: 200 mJ; 250 mJ; 300 mJ and 350 mJ. The results evidenced the Laser incidence angle importance; it is an essential parameter in the protocol of utilization and it should not be disregarded. The observations of this study allow to conclude that the Laser incidence angle has direct influence on the morphological aspect of the alterations produced in enamel and dentin. (author)

Enhancing structural integrity of adhesive bonds through pulsed laser surface micro-machining

KAUST Repository

Diaz, Edwin Hernandez

2015-06-01

Enhancing the effective peel resistance of plastically deforming adhesive joints through laser-based surface micro-machining Edwin Hernandez Diaz Inspired by adhesion examples commonly found in nature, we reached out to examine the effect of different kinds of heterogeneous surface properties that may replicate this behavior and the mechanisms at work. In order to do this, we used pulsed laser ablation on copper substrates (CuZn40) aiming to increase adhesion for bonding. A Yb-fiber laser was used for surface preparation of the substrates, which were probed with a Scanning Electron Microscope (SEM) and X-ray Photoelectron Spectroscopy (XPS). Heterogeneous surface properties were devised through the use of simplified laser micromachined patterns which may induce sequential events of crack arrest propagation, thereby having a leveraging effect on dissipation. The me- chanical performance of copper/epoxy joints with homogeneous and heterogeneous laser micromachined interfaces was then analyzed using the T-peel test. Fractured surfaces were analyzed using SEM to resolve the mechanism of failure and adhesive penetration within induced surface asperities from the treatment. Results confirm positive modifications of the surface morphology and chemistry from laser ablation that enable mechanical interlocking and cohesive failure within the adhesive layer. Remarkable improvements of apparent peel energy, bond toughness, and effective peel force were appreciated with respect to sanded substrates as control samples.

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

Science.gov (United States)

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

2015-07-01

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

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

Science.gov (United States)

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

2012-01-10

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

Infrared spectra, Raman laser, XRD, DSC/TGA and SEM ...

Indian Academy of Sciences (India)

Administrator

cussed and the X-ray diffraction, scanning electron microscopy (SEM) and atomic force microscope (AFM) ... acetamide as a simple organic compound at high tempera- ture has less ..... properties of selenium surface, AFM-microscopy tapping.

Pulsed laser deposition and characterization of cellulase thin films

Science.gov (United States)

Cicco, N.; Morone, A.; Verrastro, M.; Viggiano, V.

2013-08-01

Thin films of cellulase were obtained by pulsed laser deposition (PLD) on an appropriate substrate. Glycoside hydrolase cellulase has received our attention because it emerges among the antifouling enzymes (enzymes being able to remove and prevent the formation of micro-organism biofilms) used in industry and medicine field. Pressed cellulase pellets, used as target material, were ablated with pulses of a Nd-YAG laser working at wavelength of 532 nm. In this work, we evaluated the impact of PLD technique both on molecular structure and hydrolytic activity of cellulase. Characteristic chemical bonds and morphology of deposited layers were investigated by FTIR spectroscopy and SEM respectively. The hydrolytic activity of cellulase thin films was detected by a colorimetric assay.

Morphological evolution of primary TiC carbide in laser clad TiC reinforced FeAl intermetallic composite coating

Institute of Scientific and Technical Information of China (English)

陈瑶; 王华明

2003-01-01

The novel rapidly solidified TiC/FeAl composite coatings were fabricated by laser cladding on the substrate of 1Cr18Ni9Ti stainless steel, particular emphasis has been placed on the growth morphologies of TiC carbide and its growth mechanism under a constant solidification conditions. Results show that the growth morphology of TiC carbide strongly depends upon the nucleation process and mass transportation process of TiC forming elements in laser melt pool. With increasing amount of titanium and carbon in melt pool, the growth morphology of TiC carbide changes from block-like to star-like and well-developed dendrite. As the amount of titanium and carbon increases further, TiC carbide particles are found to be irregular polyhedral block. Although the growth morphologies of TiC are various,their advancing fronts are all faceted, illustrating that TiC carbide grows by the mechanism of lateral ledge growth.

Controlling the stainless steel surface wettability by nanosecond direct laser texturing at high fluences

Science.gov (United States)

Gregorčič, P.; Šetina-Batič, B.; Hočevar, M.

2017-12-01

This work investigates the influence of the direct laser texturing at high fluences (DLT-HF) on surface morphology, chemistry, and wettability. We use a Nd:YAG laser ( λ = 1064 nm) with pulse duration of 95 ns to process stainless steel surface. The surface morphology and chemistry after the texturing is examined by using scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDS), and electron backscatter diffraction (EBSD), while the surface wettability is evaluated by measuring the static contact angle. Immediately after the texturing, the surface is superhydrophilic in a saturated Wenzel regime. However, this state is not stable and the superhydrophilic-to-superhydrophobic transition happens if the sample is kept in atmospheric air for 30 days. After this period, the laser-textured stainless steel surface expresses lotus-leaf-like behavior. By using a high-speed camera at 10,000 fps, we measured that the water droplet completely rebound from this superhydrophobic surface after the contact time of 12 ms.

Effects of Laser Energy Density on Size and Morphology of NiO Nanoparticles Prepared by Pulsed Laser Ablation in Liquid

Energy Technology Data Exchange (ETDEWEB)

Ma, Rory; Reddy, M. Amaranatha; Kim, Tae Kyu [Pusan National University, Busan (Korea, Republic of)

2015-01-15

Metaloxide nanoparticles are of great importance to a large variety of chemical and material applications ranging from catalysts to electronic devices. Among the metal-oxide nanoparticles, NiO is one of the technologically versatile and important semiconducting materials. It has been extensively investigated because of its myriad applications in catalysts, gas sensors, Li-ion battery materials, electrochromic coatings, active optical fibers, fuel cell electrodes, and so on. The effect of laser ablation at various laser energy densities was investigated. At low energy densities, the produced nanoparticles were of irregular morphology with an average size of 2.4 nm. At higher laser energy densities, the produced nanoparticles were spherical, with a polycrystalline structure and their average size was around 10 nm. More detailed investigations on effects of laser wavelength and energy density as well as the particle size effect on the catalytic activity of synthesized NiO nanoparticles will be investigated in future works.

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

Science.gov (United States)

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

2012-11-01

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

SEM-668-G2（日东科技）

Institute of Scientific and Technical Information of China (English)

无

2005-01-01

SEM-668-G2比SEM-668在视觉技术上更加精湛，采用美国AGILENT（安提伦）LASER 5519A及HP的双重频率技术，加强运动；隹确性。在智能化印刷头上，SEM-668-G2印刷质量更加均匀、稳定，操作界面更加简易、更加人性化。在综合性能上更加卓越，保证实现现代化的生产效率。产品体具性能如下：SEM-668-G2视觉全自动印刷机

Surface modifications induced by pulsed-laser texturing—Influence of laser impact on the surface properties

Energy Technology Data Exchange (ETDEWEB)

Costil, S., E-mail: sophie.costil@utbm.fr [IRTES-LERMPS, Université de Technologie de Belfort - Montbéliard, site de Sévenans, 90010 Belfort Cedex (France); Lamraoui, A.; Langlade, C. [IRTES-LERMPS, Université de Technologie de Belfort - Montbéliard, site de Sévenans, 90010 Belfort Cedex (France); Heintz, O.; Oltra, R. [ICB, Université de Bourgogne, 21078 Dijon Cedex (France)

2014-01-01

Laser cleaning technology provides a safe, environmentally friendly and very cost effective way to improve cleaning and surface preparation of metallic materials. Compared with efficient cleaning processes, it can avoid the disadvantages of ductile materials prepared by conventional technologies (cracks induced by sand-blasting for example) and treat only some selected areas (due to the optical fibers). By this way, laser technology could have several advantages and expand the range of thermal spraying. Moreover, new generations of lasers (fiber laser, disc laser) allow the development of new methods. Besides a significant bulk reduction, no maintenance, low operating cost, laser fibers can introduce alternative treatments. Combining a short-pulse laser with a scanner allows new applications in terms of surface preparation. By multiplying impacts using scanning laser, it is possible to shape the substrate surface to improve the coating adhesion as well as the mechanical behaviour. In addition, during the interactions of the laser beam with metallic surfaces, several modifications can be induced and particularly thermal effects. Indeed, under ambient conditions, a limited oxidation of the clean surface can occur. This phenomenon has been investigated in detail for silicon but few works have been reported concerning metallic materials. This paper aims at studying the surface modifications induced on aluminium alloy substrates after laser texturing. After morphological observations (SEM), a deeper surface analysis will be performed using XPS (X-ray photoelectron spectroscopy) measures and microhardness testing.

Laser-induced microstructural development and phase evolution in magnesium alloy

International Nuclear Information System (INIS)

Guan, Y.C.; Zhou, W.; Li, Z.L.; Zheng, H.Y.

2014-01-01

Highlights: • Secondary phase evolution caused by laser processing was firstly reported. • Microstructure development was controlled by heat flow thermodynamics and kinetics. • Solid-state transformation resulted in submicron and nano-scale precipitates. • Cluster-shaped particles in overlapped region were due to precipitation coarsening. • Properties of materials can be tailored selectively by laser processing. -- Abstract: Secondary phase plays an important role in determining microstructures and properties of magnesium alloys. This paper focuses on laser-induced microstructure development and secondary phase evolution in AZ91D Mg alloy studied by SEM, TEM and EDS analyses. Compared to bulk shape and lamellar structure of the secondary phase in as-received cast material, rapid-solidified microstructures with various morphologies including nano-precipitates were observed in laser melt zone. Formation mechanisms of microstructural evolution and effect of phase development on surface properties were further discussed

Effect of pulsed laser parameters on in-situ TiC synthesis in laser surface treatment

Science.gov (United States)

Hamedi, M. J.; Torkamany, M. J.; Sabbaghzadeh, J.

2011-04-01

Commercial titanium sheets pre-coated with 300-μm thick graphite layer were treated by employing a pulsed Nd:YAG laser in order to enhance surface properties such as wear and erosion resistance. Laser in-situ alloying method produced a composite layer by melting the titanium substrate and dissolution of graphite in the melt pool. Correlations between pulsed laser parameters, microstructure and microhardness of the synthesized composite coatings were investigated. Effects of pulse duration and overlapping factor on the microstructure and hardness of the alloyed layer were deduced from Vickers micro-indentation tests, XRD, SEM and metallographic analyses of cross sections of the generated layer. Results show that the composite cladding layer was constituted with TiC intermetallic phase between the titanium matrix in particle and dendrite forms. The dendritic morphology of composite layer was changed to cellular grain structure by increasing laser pulse duration and irradiated energy. High values of the measured hardness indicate that deposited titanium carbide increases in the conditions with more pulse duration and low process speed. This occurs due to more dissolution of carbon into liquid Ti by heat input increasing and positive influence of the Marangoni flow in the melted zone.

Study on morphology of high-aspect-ratio grooves fabricated by using femtosecond laser irradiation and wet etching

International Nuclear Information System (INIS)

Chen, Tao; Pan, An; Li, Cunxia; Si, Jinhai; Hou, Xun

2015-01-01

Highlights: • We studied morphologies of silicon grooves fabricated by laser irradiation and wet etching. • We found nano-ripple structures formed on the groove sidewall. • Formations of nano-ripples were due to the formation of standing wave and nanoplanes. • Remaining debris on the groove bottom was removed by KOH etching. - Abstract: Morphologies of high-aspect-ratio silicon grooves fabricated by using femtosecond laser irradiation and selective chemical etching of hydrofluoric acid (HF) were studied. Oxygen was deeply doped into silicon under femtosecond laser irradiation in air, and then the oxygen-doped regions were removed by HF etching to form high-aspect-ratio grooves. After HF etching, periodic nano-ripples which were induced in silicon by femtosecond laser were observed on the groove sidewalls. The ripple orientation was perpendicular or parallel to the laser propagation direction (z direction), which depended on the relative direction between the laser polarization direction and the scanning direction. The formation of nano-ripples with orientations perpendicular to z direction could be attributed to the standing wave generated by the interference of the incident light and the reflected light in z direction. The formation of nano-ripples with orientations parallel to z direction could be attributed to the formation of self-organized periodic nanoplanes (bulk nanogratings) induced by femtosecond laser inside silicon. Materials in the tail portion of laser-induced oxygen doping (LIOD) regions were difficult to be etched by HF solution due to low oxygen concentration. The specimen was etched further in KOH solution to remove remaining materials in LIOD regions and all-silicon grooves were fabricated

Heterochrony in mandible development of larval shrimp (Decapoda: Caridea)--a comparative morphological SEM study of two carideans.

Science.gov (United States)

Batel, Annika; Melzer, Roland R; Anger, Klaus; Geiselbrecht, Hannes

2014-11-01

Mandible development in the larval stages I-V of two palaemonid shrimp species, Palaemon elegans and Macrobrachium amazonicum, was analyzed using scanning electron microscopy, light microscopy, and confocal laser scanning microscopy. In contrast to the zoea I of P. elegans, first-stage larvae of M. amazonicum are nonfeeding. At hatching, the morphology of the mandibles is fully expressed in P. elegans, while it appears underdeveloped in M. amazonicum, presenting only small precursors of typical caridean features. In successive zoeal stages, both species show similar developmental changes, but the mandibular characters of the larvae in M. amazonicum were delayed compared to the equivalent stages in P. elegans, especially in the development of submarginal setae and mandible size. In conclusion, our results indicate heterochrony (postdisplacement) of mandible development in M. amazonicum compared to that in P. elegans, which is related to initial lack of mandible functionality or planktivorous feeding at hatching, respectively. This conclusion is supported by comparison with other palaemonid zoeae exhibiting different feeding modes. Our data suggest that an evolutionary ground pattern of mandible morphology is present even in species with nonfeeding first-stage larvae. © 2014 Wiley Periodicals, Inc.

W-1% La2O3 Submitted to a Single Laser Pulse: Effect of Particles on Heat Transfer and Surface Morphology

Directory of Open Access Journals (Sweden)

Pasquale Gaudio

2018-05-01

Full Text Available W-1% La2O3 has been irradiated by a single laser pulse (λ = 1064 nm, pulse duration τ ≈ 15 ns, pulse energy Ep ≈ 4 J, spot size Φ = 200 μm, surface power density I = 8.5 × 1011 W·cm−2 to simulate the effects of transient thermal loads of high energy occurring in a tokamak under operative conditions. The samples have been then examined by scanning electron microscope (SEM observations to investigate erosion effects and surface morphological features. A surface depression forms in the spot central area surrounded by a ridge due to the movement of molten metal. Owing to the burst of gas bubbles, hemispherical cavities of about 10 μm and deposited droplets are observed in the ridge while the zones surrounding the ridge thermal stresses arising from fast heating and successive cooling produce an extended network of micro-cracks that often follow grain boundaries. The results are discussed and compared to those obtained in a previous work on pure bulk W.

Laser fiber cleaving techniques: effects on tip morphology and power output.

Science.gov (United States)

Vassantachart, Janna M; Lightfoot, Michelle; Yeo, Alexander; Maldonado, Jonathan; Li, Roger; Alsyouf, Muhannad; Martin, Jacob; Lee, Michael; Olgin, Gaudencio; Baldwin, D Duane

2015-01-01

Proper cleaving of reusable laser fibers is needed to maintain optimal functionality. This study quantifies the effect of different cleaving tools on power output of the holmium laser fiber and demonstrates morphologic changes using microscopy. The uncleaved tips of new 272 μm reusable laser fibers were used to obtain baseline power transmission values at 3 W (0.6 J, 5 Hz). Power output for each of four cleaving techniques-11-blade scalpel, scribe pen cleaving tool, diamond cleaving wheel, and suture scissors-was measured in a single-blinded fashion. Dispersion of light from the fibers was compared with manufacturer specifications and rated as "ideal," "acceptable," or "unacceptable" by blinded reviewers. The fiber tips were also imaged using confocal and scanning electron microscopy. Independent samples Kruskal-Wallis test and chi square were used for statistical analysis (αtrend that was highly significant (Ptrend as the power output results (P<0.001). Microscopy showed that the scribe pen produced small defects along the fiber cladding but maintained a smooth, flat core surface. The other cleaving techniques produced defects on both the core and cladding. Cleaving techniques produce a significant effect on the initial power transmitted by reusable laser fibers. The scribe pen cleaving tool produced the most consistent and highest average power output.

Evaluation of Static Friction of Polycrystalline Ceramic Brackets after Conditioning with Different Powers of Er:YAG Laser.

Science.gov (United States)

Arash, Valiollah; Javanmard, Saeed; Eftekhari, Zeinab; Rahmati-Kamel, Manouchehr; Bahadoram, Mohammad

2015-01-01

This research aimed to reduce the friction between the wire and brackets by Er:YAG laser. To measure the friction between the wires and brackets in 0° and 10° of wire angulations, 40 polycrystalline ceramic brackets (Hubit, South Korea) were divided into 8 study groups and irradiated by 100, 200, and 300 mj/s of Er:YAG laser power. Two groups of brackets were not irradiated. The friction between the wires and brackets was measured with universal testing machine (SANTAM) with a segment of .019 × .025 SS wire pulled out of the slot of bracket. ANOVA and t-test were used for analyzing the results. To evaluate the effect of the laser on surface morphology of the bracket, SEM evaluations were carried out. The mean frictional resistances between the brackets and wires with 0° of angulation by increasing the laser power decreased compared with control group, but, in 10° of angulation, the friction increased regardless of the laser power and was comparable to the friction of nonirradiated brackets. Furthermore, with each laser power, frictional resistance of brackets in 10° of angulation was significantly higher than 0° of angulation. These results were explained by SEM images too.

In vitro evaluation of the morphologic changes on the root dentine irradiated by CO{sub 2} laser associated or not to calcium hydroxide application; Avaliacao in vitro das alteracoes morfologicas da superficie da dentina radicular irradiada pelo laser de CO{sub 2} associado ou nao a aplicacao de hidroxido de calcio

Energy Technology Data Exchange (ETDEWEB)

Romano, Ana Cristina Cury Camargo

2003-07-01

This in vitro study has evaluated the structural changes on the root dentine irradiated by a CO{sub 2} laser associated or not to calcium hydroxide application, from the irradiated surface analysis by means of Scanning Electronic Microscopy (SEM). The purpose of this evaluation has been the study of an alternative method for the treatment of dentine hypersensitivity. Fourteen human teeth were utilized, third molars, divided into 7 groups. Group I (control group) to which no treatment was applied; Groups II, III and IV were given an application of Ca (OH){sub 2} paste followed by C0{sub 2} laser irradiation, lasting 5 seconds each with intervals of 10 seconds between each application, with continuous emission, power of 0.5 W (Group II), 1.0 W (Group III), and 1.5 W (Group IV); Groups V, VI, and VII were given laser irradiations without the Ca (OH){sub 2} paste following the same parameters applied to groups II, III, and IV respectively. Morphologic changes suggesting to fusion and re-solidification have been observed, as well as the presence of material obstructing the whole analyzed surface on groups II, III, and IV (laser + Ca (OH){sub 2}). As for groups V, VI, and VII, it has been observed fusion, re-solidification, and cracks, and these results being statistically significant when compared the '(Ca (OH){sub 2})' groups to the laser groups. No statistically significant differences were observed regarding the different powers applied in the groups that used the same treatment. Despite this result, it can be stated that powers above 1.0 W (DP = 125,38 W/cm{sup 2}) are unfavorable due to the undesirable morphologic alterations and aesthetic compromising. (author)

In vitro evaluation of the morphologic changes on the root dentine irradiated by CO{sub 2} laser associated or not to calcium hydroxide application; Avaliacao in vitro das alteracoes morfologicas da superficie da dentina radicular irradiada pelo laser de CO{sub 2} associado ou nao a aplicacao de hidroxido de calcio

Energy Technology Data Exchange (ETDEWEB)

Romano, Ana Cristina Cury Camargo

2003-07-01

This in vitro study has evaluated the structural changes on the root dentine irradiated by a CO{sub 2} laser associated or not to calcium hydroxide application, from the irradiated surface analysis by means of Scanning Electronic Microscopy (SEM). The purpose of this evaluation has been the study of an alternative method for the treatment of dentine hypersensitivity. Fourteen human teeth were utilized, third molars, divided into 7 groups. Group I (control group) to which no treatment was applied; Groups II, III and IV were given an application of Ca (OH){sub 2} paste followed by C0{sub 2} laser irradiation, lasting 5 seconds each with intervals of 10 seconds between each application, with continuous emission, power of 0.5 W (Group II), 1.0 W (Group III), and 1.5 W (Group IV); Groups V, VI, and VII were given laser irradiations without the Ca (OH){sub 2} paste following the same parameters applied to groups II, III, and IV respectively. Morphologic changes suggesting to fusion and re-solidification have been observed, as well as the presence of material obstructing the whole analyzed surface on groups II, III, and IV (laser + Ca (OH){sub 2}). As for groups V, VI, and VII, it has been observed fusion, re-solidification, and cracks, and these results being statistically significant when compared the '(Ca (OH){sub 2})' groups to the laser groups. No statistically significant differences were observed regarding the different powers applied in the groups that used the same treatment. Despite this result, it can be stated that powers above 1.0 W (DP = 125,38 W/cm{sup 2}) are unfavorable due to the undesirable morphologic alterations and aesthetic compromising. (author)

Clinical and morphologic evaluation of Er:YAG laser action at the front of cervical dentinal hypersensitivity; Avaliacao clinica e morfologica da acao do laser de Er:YAG frente a hipersensibilidade dentinaria cervical

Energy Technology Data Exchange (ETDEWEB)

Rocha, Dalva Maria

2001-07-01

This work was achieved in vivo and in vitro to evaluate the efficiency of Er:YAG laser in the cervical dentinal hypersensitivity treatment (HSDC). The Clinical study was achieved in patients with HSDC. The treatment was realized in five sessions: the first for selection, the second for exams (clinic and X-Ray) and trying to remove the etiologic factors that could cause the HSDC. The third and fourth sessions were subjected to the radiation with that protocol: 60 mJ energy ,2 Hz frequency, 6 mm out of focus, under air cooling, 20 seconds each application which the same was repeated four times with one minute breaks, which scanning movements and without using anaesthetics. The fifth was evaluation. The patients were evaluated and registered in a subject scale of pain 0 to 3, in the beginning and end of each session of irradiation, and one month after the last session. The results showed that for the irradiated group occurs significant differences in the beginning of each session and between. For the control group did not occur significant differences in the beginning and after each session, but did show a difference between the sessions. As the control group as the irradiated group, had reduction of sensibility between the session. For the morphologic study nine teeth were selected, 7 molars and 2 pre-molars from operative dentistry discipline. Half of the surface was irradiated with Er:YAG laser, the same protocol used in vivo, and the other half was used as a control without receiving any laser irradiation. Subsequently, specimens were prepared for SEM examinations. The results showed that laser treated surfaces showed a reduction of dentine tubular diameter with partial or total closure of the dentine tubules. For the control group, it was observed bigger amounts smear layer and open dentine tubular. The results obtained indicated that the Er:YAG laser can contribute to the HSDC treatment. (author)

Influence of wavelength on the laser removal of lichens colonizing heritage stone

International Nuclear Information System (INIS)

Sanz, M.; Oujja, M.; Ascaso, C.; Pérez-Ortega, S.; Souza-Egipsy, V.; Fort, R.; Rios, A. de los; Wierzchos, J.; Cañamares, M.V.; Castillejo, M.

2017-01-01

Highlights: • Optimal laser removal conditions depend on light absorption of lichen species. • Highly UV absorbing species (C. vitellina) removed by 266 nm nanosecond pulses. • Dual 1064-266/355 nm irradiation strongly damages a large variety of lichen species. • Calcium inside the lichen thallus prevents the damaging effect of laser irradiation. - Abstract: Laser irradiation of lichen thalli on heritage stones serves for the control of epilithic and endolithic biological colonizations. In this work we investigate rock samples from two quarries traditionally used as source of monumental stone, sandstone from Valonsadero (Soria, Spain) and granite from Alpedrete (Madrid, Spain), in order to find conditions for efficient laser removal of lichen thalli that ensure preservation of the lithic substrate. The samples presented superficial areas colonized by different types of crustose lichens, i.e. Candelariella vitellina, Aspicilia viridescens, Rhizocarpon disporum and Protoparmeliopsis muralis in Valonsadero samples and P. cf. bolcana and A. cf. contorta in Alpedrete samples. A comparative laser cleaning study was carried out on the mentioned samples with ns Q-switched Nd:YAG laser pulses of 1064 nm (fundamental radiation), 355 nm (3rd harmonic) and 266 nm (4th harmonic) and sequences of IR-UV pulses. A number of techniques such as UV-Vis absorption spectroscopy, stereomicroscopy, scanning electron microscopy (SEM) at low vacuum, SEM with backscattered electron imaging (SEM-BSE), electron dispersive spectroscopy (EDS) and FT-Raman spectroscopy were employed to determine the best laser irradiation conditions and to detect possible structural, morphological and chemical changes on the irradiated surfaces. The results show that the laser treatment does not lead to the complete removal of the studied lichen thalli, although clearly induces substantial damage, in the form of loss of the lichen upper cortex and damage to the algal layer. In the medium term these

Influence of wavelength on the laser removal of lichens colonizing heritage stone

Energy Technology Data Exchange (ETDEWEB)

Sanz, M., E-mail: mikel.sanz@iqfr.csic.es [Instituto de Química Física Rocasolano (IQFR-CSIC), Serrano 119, 28006, Madrid (Spain); Oujja, M. [Instituto de Química Física Rocasolano (IQFR-CSIC), Serrano 119, 28006, Madrid (Spain); Ascaso, C. [Museo Nacional de Ciencias Naturales (MNCN-CSIC), José Gutiérrez Abascal 2, 28006, Madrid (Spain); Pérez-Ortega, S. [Real Jardín Botánico (RJB-CSIC), Plaza de Murillo 2, 28014, Madrid (Spain); Souza-Egipsy, V. [Instituto de Estructura de la Materia (IEM-CSIC), Serrano 121, 28006, Madrid (Spain); Fort, R. [Instituto de Geociencias (IGEO-CSIC, UCM), José Antonio Nováis 12, 28040, Madrid (Spain); Rios, A. de los; Wierzchos, J. [Museo Nacional de Ciencias Naturales (MNCN-CSIC), José Gutiérrez Abascal 2, 28006, Madrid (Spain); Cañamares, M.V. [Instituto de Estructura de la Materia (IEM-CSIC), Serrano 121, 28006, Madrid (Spain); Castillejo, M. [Instituto de Química Física Rocasolano (IQFR-CSIC), Serrano 119, 28006, Madrid (Spain)

2017-03-31

Highlights: • Optimal laser removal conditions depend on light absorption of lichen species. • Highly UV absorbing species (C. vitellina) removed by 266 nm nanosecond pulses. • Dual 1064-266/355 nm irradiation strongly damages a large variety of lichen species. • Calcium inside the lichen thallus prevents the damaging effect of laser irradiation. - Abstract: Laser irradiation of lichen thalli on heritage stones serves for the control of epilithic and endolithic biological colonizations. In this work we investigate rock samples from two quarries traditionally used as source of monumental stone, sandstone from Valonsadero (Soria, Spain) and granite from Alpedrete (Madrid, Spain), in order to find conditions for efficient laser removal of lichen thalli that ensure preservation of the lithic substrate. The samples presented superficial areas colonized by different types of crustose lichens, i.e. Candelariella vitellina, Aspicilia viridescens, Rhizocarpon disporum and Protoparmeliopsis muralis in Valonsadero samples and P. cf. bolcana and A. cf. contorta in Alpedrete samples. A comparative laser cleaning study was carried out on the mentioned samples with ns Q-switched Nd:YAG laser pulses of 1064 nm (fundamental radiation), 355 nm (3rd harmonic) and 266 nm (4th harmonic) and sequences of IR-UV pulses. A number of techniques such as UV-Vis absorption spectroscopy, stereomicroscopy, scanning electron microscopy (SEM) at low vacuum, SEM with backscattered electron imaging (SEM-BSE), electron dispersive spectroscopy (EDS) and FT-Raman spectroscopy were employed to determine the best laser irradiation conditions and to detect possible structural, morphological and chemical changes on the irradiated surfaces. The results show that the laser treatment does not lead to the complete removal of the studied lichen thalli, although clearly induces substantial damage, in the form of loss of the lichen upper cortex and damage to the algal layer. In the medium term these

Enhancing the antibacterial performance of orthopaedic implant materials by fibre laser surface engineering

DEFF Research Database (Denmark)

Chan, Chi-Wai; Carson, Louise; Smith, Graham C.

2017-01-01

to the effort on enhancing osseointegration, wear and corrosion resistance of implant materials. In this study, the effects of laser surface treatment on enhancing the antibacterial properties of commercially pure (CP) Ti (Grade 2), Ti6Al4V (Grade 5) and CoCrMo alloy implant materials were studied and compared...... for the first time. Laser surface treatment was performed by a continuous wave (CW) fibre laser with a near-infrared wavelength of 1064 nm in a nitrogen-containing environment. Staphylococcus aureus, commonly implicated in infection associated with orthopaedic implants, was used to investigate the antibacterial...... properties of the laser-treated surfaces. The surface roughness and topography of the laser-treated materials were analysed by a 2D roughness testing and by AFM. The surface morphologies before and after 24 h of bacterial cell culture were captured by SEM, and bacterial viability was determined using live...

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

DEFF Research Database (Denmark)

Wierzbicki, Rafal; Købler, Carsten; Jensen, Mikkel Ravn Boye

2013-01-01

Using high resolution focused ion beam scanning electron microscopy (FIB-SEM) we study the details of cell-nanostructure interactions using serial block face imaging. 3T3 Fibroblast cellular monolayers are cultured on flat glass as a control surface and on two types of nanostructured scaffold...... substrates made from silicon black (Nanograss) with low- and high nanowire density. After culturing for 72 hours the cells were fixed, heavy metal stained, embedded in resin, and processed with FIB-SEM block face imaging without removing the substrate. The sample preparation procedure, image acquisition...

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

Science.gov (United States)

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

2017-12-15

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

Verification of a characterization method of the laser-induced selective activation based on industrial lasers

DEFF Research Database (Denmark)

Zhang, Yang; Hansen, Hans Nørgaard; Tang, Peter T.

2013-01-01

In this article, laser-induced selective activation (LISA) for subsequent autocatalytic copper plating is performed by several types of industrial scale lasers, including a Nd:YAG laser, a UV laser, a fiber laser, a green laser, and a short pulsed laser. Based on analysis of all the laser......-machined surfaces, normalized bearing area curves and parameters are used to characterize the surface quantitatively. The range of normalized bearing area curve parameters for plate-able surface is suggested. PBT/PET with 40 % glass fiber was used as the substrate material. For all of the studied lasers......, the parameters were varied in a relatively large range, and matrixes of the laser-machined surface were obtained. The topography of those laser-machined surfaces was examined by scanning electronic microscope (SEM). For each sample examined by SEM, there was an identical workpiece plated by for 90 min...

Effect of laser energy on the electrical transport properties of La{sub 0.67}Ca{sub 0.33}MnO{sub 3}:Ag{sub 0.2} films by pulsed laser deposition technique

Energy Technology Data Exchange (ETDEWEB)

Zhang, Yalin; Chen, Qingming; Jin, Fei; Chen, Xiaohui; Li, Zhiyu; Li, Di; Zhang, Hui [Kunming University of Science and Technology, Faculty of Materials Science and Engineering, Kunming (China)

2017-09-15

La{sub 0.67}Ca{sub 0.33}MnO{sub 3} (LCMO):Ag{sub 0.2} films were grown on LaAlO{sub 3} (LAO) substrates (100) by pulsed laser deposition (PLD) technique with various incident laser energies. The surface morphologies and the thicknesses of the films were studied by atomic force microscopy (AFM) and scanning electron microscopy (SEM), respectively. The crystal structures were analyzed by X-ray, diffraction (XRD), and the temperature dependence of the resistivity (ρ-T) of the films was studied by the standard four-probe method. It can be found that the crystal quality, surface morphology, metal-insulator transition temperature (T{sub p}), and temperature coefficient of resistance (TCR) of the LCMO:Ag{sub 0.2} films are changed with various laser energy. The highest T{sub p} 287 K is obtained with 300 mJ laser energy; meanwhile, the optimal TCR 13.5% K{sup -1} is achieved. The results suggest that the electrical transport properties of LCMO:Ag{sub 0.2} films are affected by the interface-induced compressive stress, the oxygen balance, and the double exchange between Mn{sup 3+}-O-Mn{sup 4+}. (orig.)

Surface morphological modification of crosslinked hydrophilic co-polymers by nanosecond pulsed laser irradiation

Energy Technology Data Exchange (ETDEWEB)

Primo, Gastón A.; Alvarez Igarzabal, Cecilia I. [IMBIV (CONICET), Departamento de Química Orgánica, Facultad de Ciencias Químicas, Universidad Nacional de Córdoba, Haya de la Torre y Medina Allende, Edificio de Ciencias II, Ciudad Universitaria, Córdoba X5000HUA (Argentina); Pino, Gustavo A.; Ferrero, Juan C. [INFIQC (CONICET), Departamento de Fisicoquímica, Facultad de Ciencias Químicas, and Centro Láser de Ciencias Moleculares, Universidad Nacional de Córdoba, Córdoba X5000IUS (Argentina); Rossa, Maximiliano, E-mail: mrossa@fcq.unc.edu.ar [INFIQC (CONICET), Departamento de Fisicoquímica, Facultad de Ciencias Químicas, and Centro Láser de Ciencias Moleculares, Universidad Nacional de Córdoba, Córdoba X5000IUS (Argentina)

2016-04-30

Graphical abstract: - Highlights: • Laser-induced surface modification of crosslinked hydrophilic co-polymers by ns pulses. • Formation of ablation craters observed under most of the single-pulse experimental conditions. • UV laser foaming of dried hydrogel samples resulting from single- and multiple-pulse experiments. • Threshold values of the incident laser fluence reported for the observed surface modifications. • Lower threshold fluences for acrylate-based, compared to acrylamide-based hydrogels. - Abstract: This work reports an investigation of the surface modifications induced by irradiation with nanosecond laser pulses of ultraviolet and visible wavelengths on crosslinked hydrophilic co-polymeric materials, which have been functionalized with 1-vinylimidazole as a co-monomer. A comparison is made between hydrogels differing in the base co-monomer (N,N-dimethylaminoethyl methacrylate and N-[3-(dimethylamino)propyl] methacrylamide) and in hydration state (both swollen and dried states). Formation of craters is the dominant morphological change observed by ablation in the visible at 532 nm, whereas additional, less aggressive surface modifications, chiefly microfoams and roughness, are developed in the ultraviolet at 266 nm. At both irradiation wavelengths, threshold values of the incident laser fluence for the observation of the various surface modifications are determined under single-pulse laser irradiation conditions. It is shown that multiple-pulse irradiation at 266 nm with a limited number of laser shots can be used alternatively for generating a regular microfoam layer at the surface of dried hydrogels based on N,N-dimethylaminoethyl methacrylate. The observations are rationalized on the basis of currently accepted mechanisms for laser-induced polymer surface modification, with a significant contribution of the laser foaming mechanism. Prospective applications of the laser-foamed hydrogel matrices in biomolecule immobilization are suggested.

SERS activity of silver and gold nanostructured thin films deposited by pulsed laser ablation

Science.gov (United States)

Agarwal, N. R.; Tommasini, M.; Fazio, E.; Neri, F.; Ponterio, R. C.; Trusso, S.; Ossi, P. M.

2014-10-01

Nanostructured Au and Ag thin films were obtained by nanosecond pulsed laser ablation in presence of a controlled Ar atmosphere. Keeping constant other deposition parameters such as target-to-substrate distance, incidence angle, laser wavelength and laser fluence, the film morphology, revealed by SEM, ranges from isolated NPs to island structures and sensibly depends on gas pressure (10-100 Pa) and on the laser pulse number (500-3 × 10). The control of these two parameters allows tailoring the morphology and correspondingly the optical properties of the films. The position and width of the surface plasmon resonance peak, in fact, can be varied with continuity. The films showed remarkable surface-enhanced Raman activity (SERS) that depends on the adopted deposition conditions. Raman maps were acquired on micrometer-sized areas of both silver and gold substrates selected among those with the strongest SERS activity. Organic dyes of interest in cultural heritage studies (alizarin, purpurin) have been also considered for bench marking the substrates produced in this work. Also the ability to detect the presence of biomolecules was tested using lysozyme in a label free configuration.

Heating effect of substrate of pulsed laser ablation deposition technique towards the orientation of carbon microstructure

International Nuclear Information System (INIS)

Choy, L.S.; Irmawati Ramli; Noorhana Yahya; Abdul Halim Shaari

2009-01-01

Full text: Carbon thin film has been successfully deposited by second harmonic Nd:YAG pulsed laser ablation deposition, PLAD. The topology and morphology of the deposited layers was studied by scanning electron microscopy (SEM) whereas emission dispersion X-ray (EDX) was used to determine the existence of elements that constitutes the microstructure. Substrate heated at 500 degree Celsius during the laser ablation showed the most homogenous lollipop microstructure as compared to mainly pillars of microstructure ablated at lower substrate temperature. It is found that this also avoid further diffusion of carbon into catalyst in forming iron carbide. (author)

Lithium niobate bulk crystallization promoted by CO{sub 2} laser radiation

Energy Technology Data Exchange (ETDEWEB)

Ferreira, N.M., E-mail: nmferreira@ua.pt [i3N - Aveiro, Physics Department, Aveiro University, Campus Universitario de Santiago, 3810-193 Aveiro (Portugal); Costa, F.M. [i3N - Aveiro, Physics Department, Aveiro University, Campus Universitario de Santiago, 3810-193 Aveiro (Portugal); Nogueira, R.N. [Instituto de Telecomunicacoes, 3810-193 Aveiro (Portugal); Graca, M.P.F. [i3N - Aveiro, Physics Department, Aveiro University, Campus Universitario de Santiago, 3810-193 Aveiro (Portugal)

2012-09-15

Highlights: Black-Right-Pointing-Pointer Crystallization of LiNbO{sub 3} nanocrystals in a SiO{sub 2} matrix by CO{sub 2} laser irradiation process. Black-Right-Pointing-Pointer Samples heat-treated at 650 Degree-Sign C (4 h) and laser treated (4 W/500 s) show similar morphology. Black-Right-Pointing-Pointer Glass-ceramics produced by laser process requires a very low processing time. - Abstract: The crystallization induced by laser radiation is a very promising technique to promote glass/ceramic transformation, being already used to produce crystalline patterns on glass surfaces. In this work, a SiO{sub 2}-Li{sub 2}O-Nb{sub 2}O{sub 5} glass, prepared by the sol-gel route, was submitted to CO{sub 2} laser radiation and conventional heat-treatments in order to induce the LiNbO{sub 3} crystallization. The structure and morphology of the samples prepared by both routes was analyzed as a function of exposure time, radiation power and heat-treatment temperatures by XRD, Raman spectroscopy and SEM. The results reveal a correlation between the crystallization degree of LiNbO{sub 3} particles and glass matrix with the heat treatment type and experimental parameters. An heat-treatment at 650 Degree-Sign C/4 h was necessary to induce crystallization in heat treatments samples while 4 W/500 s was enough for laser radiation ones, corresponding a reduction time processing of {approx}14 000 s.

Structural, morphological and local electric properties of TiO2 thin films grown by pulsed laser deposition

International Nuclear Information System (INIS)

Gyoergy, E; Pino, A Perez del; Sauthier, G; Figueras, A; Alsina, F; Pascual, J

2007-01-01

Titanium dioxide (TiO 2 ) thin films were synthesized on (1 0 0) Si substrates by reactive pulsed laser deposition (PLD) technique. A frequency quadrupled Nd : YAG (λ = 266 nm, τ FWHM ≅ 5 ns, ν = 10 Hz) laser source was used for the irradiations of metallic Ti targets. The experiments were performed in controlled oxygen atmosphere. Crystallinity, surface morphology and local electric properties of the obtained oxide thin films were investigated by x-ray diffractometry, micro-Raman spectroscopy and current sensing atomic force microscopy. An inter-relation was found between the surface morphology, the crystalline structure and the nano-scale electric properties which open the possibility of synthesizing by the PLD technique TiO 2 thin films with tunable functional properties for future applications such as photocatalysts, gas sensors or solar energy converters

Influence of the incidence angle on the morphology of enamel and dentin under Er:YAG laser irradiation; Estudo da influencia da angulacao do feixe laser na morfologia de esmalte e dentina irradiados com laser de Er:YAG

Energy Technology Data Exchange (ETDEWEB)

Junqueira Junior, Duilio Naves

2002-07-01

The purpose of this study is to make an in vitro evaluation, using scanning electron microscopy, of the influence of the laser beam irradiation angle on the enamel and dentin morphology. These tissues were both irradiated by Er:YAG Laser, with the same energy parameter. Twenty-four incisive bovine teeth were used, separated in eight groups, four of enamel, and four of dentin, with three specimens in each group. Each specimen was submitted to three laser applications, varying the incidence angle, between the laser and the tooth surface, at 90, 50 and 20 degrees. The applied frequency was 2 Hz, with 20 pulses in each application. The KaVo Key Laser 3 was employed, wavelength at 2940 nm, adjustable energy from 40 to 600 mJ and repetition rate from 1 to 25 Hz. The groups were distributed according to the energy parameter as follows - enamel: 250 mJ; 300 mJ; 350 mJ and 400 mJ; dentin: 200 mJ; 250 mJ; 300 mJ and 350 mJ. The results evidenced the Laser incidence angle importance; it is an essential parameter in the protocol of utilization and it should not be disregarded. The observations of this study allow to conclude that the Laser incidence angle has direct influence on the morphological aspect of the alterations produced in enamel and dentin. (author)

Histological observation on dental hard tissue irradiated by ultrashort-pulsed laser

Science.gov (United States)

Uchizono, Takeyuki; Awazu, Kunio; Igarashi, Akihiro; Kato, Junji; Hirai, Yoshito

2006-04-01

In the field of dentistry, effectiveness of USPL irradiation is researched because USPL has less thermal side effect to dental hard tissue. In this paper, we observed morphological change and optical change of dental hard tissue irradiated by USPL for discussing the safety and effectiveness of USPL irradiation to dental hard tissues. Irradiated samples were crown enamel and root dentin of bovine teeth. Lasers were Ti:sapphire laser, which had pulse duration (P d)of 130 fsec and pulse repetition rate (f) of 1kHz and wavelength (l) of 800nm, free electron laser (FEL), which had P d of 15 μsec and f of 10Hz and wavelength of 9.6μm, and Er:YAG laser, which had P d of 250 μsec and f of 10Hz and wavelength of 2.94μm. After laser irradiation, the sample surfaces and cross sections were examined with SEM and EDX. The optical change of samples was observed using FTIR. In SEM, the samples irradiated by USPL had sharp and accurate ablation with no crack and no carbonization. But, in FEL and Er:YAG laser, the samples has rough ablation with crack and carbonization. It was cleared that the P/Ca ratio of samples irradiated by USPL had same value as non-irradiated samples. There was no change in the IR absorption spectrum between samples irradiated by USPL and non-irradiated sample. But, they of samples irradiated by FEL and Er:YAG laser, however, had difference value as non-irradiated samples. These results showed that USPL might be effective to ablate dental hard tissue without thermal damage.

fs- and ns-laser processing of polydimethylsiloxane (PDMS) elastomer: Comparative study

Energy Technology Data Exchange (ETDEWEB)

Stankova, N.E., E-mail: nestankova@yahoo.com [Institute of Electronics, Bulgarian Academy of Sciences, 72 Tsarigradsko Shose, Sofia 1784 (Bulgaria); Atanasov, P.A.; Nedyalkov, N.N.; Stoyanchov, T.R. [Institute of Electronics, Bulgarian Academy of Sciences, 72 Tsarigradsko Shose, Sofia 1784 (Bulgaria); Kolev, K.N.; Valova, E.I.; Georgieva, J.S.; Armyanov, St.A. [Rostislaw Kaischew Institute of Physical Chemistry, Bulgarian Academy of Sciences, Acad. G. Bonchev Str., Block 11, Sofia 1113 (Bulgaria); Amoruso, S.; Wang, X.; Bruzzese, R. [CNR-SPIN, Dipartimento di Scienze Fisiche, Universita degli Studi di Napoli Federico II, Complesso Universitario di Monte S. Angelo, Via Cintia, I-80126 Napoli (Italy); Grochowska, K.; Śliwiński, G. [Photophysics Department, The Szewalski Institute, Polish Academy of Sciences, 14 Fiszera St., 80-231 Gdańsk (Poland); Baert, K.; Hubin, A. [Vrije Universiteit Brussels, Faculty of Engineering, Research group, SURF “Electrochemical and Surface Engineering” (Belgium); Delplancke, M.P.; Dille, J. [Université Libre de Bruxelles, Materials Engineering, Characterization, Synthesis and Recycling (Service 4MAT), Faculté des Sciences Appliquées, 1050 Brussels (Belgium)

2015-05-01

Highlights: • fs- and ns-laser (266 and 532 nm) processing of PDMS-elastomer, in air, is studied. • High definition tracks (on the PDMS-elastomer surface) for electrodes are produced. • Selective Pt or Ni metallization of the tracks is produced via electroless plating. • Irradiated and metallized tracks are characterized by μ-Raman spectrometry and SEM. • DC resistance of Pt and Ni tracks is always between 0.5 and 15 Ω/mm. - Abstract: Medical grade polydimethylsiloxane (PDMS) elastomer is a widely used biomaterial as encapsulation and/or as substrate insulator carrier for long term neural implants because of its remarkable properties. Femtosecond (λ = 263 and 527 nm) and nanosecond (266 and 532 nm) laser processing of PDMS-elastomer surface, in air, is investigated. The influence of different processing parameters, including laser wavelength, pulse duration, fluence, scanning speed and overlapping of the subsequent pulses, on the surface activation and the surface morphology are studied. High definition tracks and electrodes are produced. Remarkable alterations of the chemical composition and structural morphology of the ablated traces are observed in comparison with the native material. Raman spectra illustrate well-defined dependence of the chemical composition on the laser fluence, pulse duration, number of pulses and wavelength. An extra peak about ∼512–518 cm{sup −1}, assigned to crystalline silicon, is observed after ns- or visible fs-laser processing of the surface. In all cases, the intensities of Si−O−Si symmetric stretching at 488 cm{sup −1}, Si−CH{sub 3} symmetric rocking at 685 cm{sup −1}, Si−C symmetric stretching at 709 cm{sup −1}, CH{sub 3} asymmetric rocking + Si−C asymmetric stretching at 787 cm{sup −1}, and CH{sub 3} symmetric rocking at 859 cm{sup −1}, modes strongly decrease. The laser processed areas are also analyzed by SEM and optical microscopy. Selective Pt or Ni metallization of the laser processed

Synthesis and characterization of titanium dioxide thin films deposited by laser ablation

International Nuclear Information System (INIS)

Escobar A, L.; Camps C, E.; Falcon B, T.; Carapia M, L.; Haro P, E.; Camacho L, M.A.

2000-01-01

In this work are presented the results obtained when TiO 2 thin films were deposited using the laser ablation technique. Thin films were deposited at different substrate temperatures, and different oxygen pressures, with the purpose of studying the influence of this deposit parameters in the structural characteristics of the films obtained. The structural characterization was realized through Raman Spectroscopy and X-ray Diffraction (XRD), the surface morphology of the layers deposited was verified by Scanning Electron Microscopy (Sem). The results show that the films obtained are of TiO 2 in rutile phase, getting this at low substrate temperatures, its morphology shows a soft surface with some spattered particles and good adherence. (Author)

Scanning electron microscopy (SEM) and X-ray dispersive spectrometry evaluation of direct laser metal sintering surface and human bone interface: a case series.

Science.gov (United States)

Mangano, Carlo; Piattelli, Adriano; Raspanti, Mario; Mangano, Francesco; Cassoni, Alessandra; Iezzi, Giovanna; Shibli, Jamil Awad

2011-01-01

Recent studies have shown that direct laser metal sintering (DLMS) produces structures with complex geometry and consequently that allow better osteoconductive properties. The aim of this patient report was to evaluate the early bone response to DLMS implant surface retrieved from human jaws. Four experimental DLMS implants were inserted in the posterior mandible of four patients during conventional dental implant surgery. After 8 weeks, the micro-implants and the surrounding tissue were removed and prepared for scanning electron microscopy (SEM) and histomorphometric analysis to evaluate the bone-implant interface. The SEM and EDX evaluations showed a newly formed tissue composed of calcium and phosphorus. The bone-to-implant contact presented a mean of 60.5 ± 11.6%. Within the limits of this patient report, data suggest that the DLMS surfaces presented a close contact with the human bone after a healing period of 8 weeks.

Tribological behaviors of UHMWPE composites with different counter surface morphologies

Science.gov (United States)

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.

Study of temperature dependence and angular distribution of poly(9,9-dioctylfluorene) polymer films deposited by matrix-assisted pulsed laser evaporation (MAPLE)

International Nuclear Information System (INIS)

Caricato, A.P.; Anni, M.; Manera, M.G.; Martino, M.; Rella, R.; Romano, F.; Tunno, T.; Valerini, D.

2009-01-01

Poly(9,9-dioctylfluorene) (PFO) polymer films were deposited by matrix-assisted pulsed laser evaporation (MAPLE) technique. The polymer was diluted (0.5 wt%) in tetrahydrofuran and, once cooled to liquid nitrogen temperature, it was irradiated with a KrF excimer laser. 10,000 laser pulses were used to deposit PFO films on Si substrates at different temperatures (-16, 30, 50 and 70 deg. C). One PFO film was deposited with 16,000 laser pulses at a substrate temperature of 50 deg. C. The morphology, optical and structural properties of the films were investigated by SEM, AFM, PL and FTIR spectroscopy. SEM inspection showed different characteristic features on the film surface, like deflated balloons, droplets and entangled polymer filaments. The roughness of the films was, at least partially, controlled by substrate heating, which however had the effect to reduce the deposition rate. The increase of the laser pulse number modified the target composition and increased the surface roughness. The angular distribution of the material ejected from the target confirmed the forward ejection of the target material. PFO films presented negligible modification of the chemical structure respect to the bulk material.

Extending ultra-short pulse laser texturing over large area

Energy Technology Data Exchange (ETDEWEB)

Mincuzzi, G., E-mail: girolamo.mincuzzi@alphanov.com; Gemini, L.; Faucon, M.; Kling, R.

2016-11-15

Highlights: • We carried out metal surface texturing (Ripples, micro grooves, Spikes) using a high power, high repetition rate, industrial, Ultra-short pulses laser. • Extremely Fast processing is shown (Laser Scan speed as high as 90 m/s) with a polygon scanner head. • Stainless steel surface blackening with Ultra-short pulses laser has been obtained with unprecedented scanspeed. • Full SEM surface characterization was carried out for all the different structures obtained. • Reflectance measurements were carried out to characterize surface reflectance. - Abstract: Surface texturing by Ultra-Short Pulses Laser (UPL) for industrial applications passes through the use of both fast beam scanning systems and high repetition rate, high average power P, UPL. Nevertheless unwanted thermal effects are expected when P exceeds some tens of W. An interesting strategy for a reliable heat management would consists in texturing with a low fluence values (slightly higher than the ablation threshold) and utilising a Polygon Scanner Heads delivering laser pulses with unrepeated speed. Here we show for the first time that with relatively low fluence it is possible over stainless steel, to obtain surface texturing by utilising a 2 MHz femtosecond laser jointly with a polygonal scanner head in a relatively low fluence regime (0.11 J cm{sup −2}). Different surface textures (Ripples, micro grooves and spikes) can be obtained varying the scan speed from 90 m s{sup −1} to 25 m s{sup −1}. In particular, spikes formation process has been shown and optimised at 25 m s{sup −1} and a full morphology characterization by SEM has been carried out. Reflectance measurements with integrating sphere are presented to compare reference surface with high scan rate textures. In the best case we show a black surface with reflectance value < 5%.

New insights into morphological features of Hadjelia truncata (Spirurida: Habronematidae), as revealed by SEM.

Science.gov (United States)

Naem, Soraya; Houston, Robin S; Sentíes-Cué, Gabriel

2013-01-01

Hadjelia truncata (Spirurida: Habronematidae) is a nematode found in the gizzard of several avian species. However, it has been reported pathogenic only in pigeons (Columba livia), in which it causes severe ventriculitis. Scanning electron microscopy (SEM) was used to study the morphological aspects of adult worms of this nematode in detail. Males and females measured 6.5-9 and 12-16.5 mm, respectively. The bodies were straight with moderate uniform thickness in both males and females, narrowing at the anterior end. The cuticle was striated transversely. The mouth was surrounded by two lateral trilobed lips, and the dorsal and ventral interlabia were present. The two cephalic papillae were present on each side lodged just behind the upper and lower bases of each lip. Around the mouth, a large amphid was seen on each lip. At the anterior end of both male and female worms, an excretory pore on the ventral side and a pair of lateral cervical papillae were observed. In the female, the vulva was located at the anterior end of the body. The lips of the vulva protruded above the body surface, and the bluntly rounded posterior end showed an anal pore and two subterminal phasmids. The posterior end of the males curved ventrally, with large caudal alae supported by four pairs of stalked precloacal papillae, a single medial precloacal papilla, two pairs of postcloacal papillae, and a cluster of small papillae on the caudal extremity. Spicules were unequal and dissimilar.

Laser surface texturing of tool steel: textured surfaces quality evaluation

Science.gov (United States)

Šugár, Peter; Šugárová, Jana; Frnčík, Martin

2016-05-01

In this experimental investigation the laser surface texturing of tool steel of type 90MnCrV8 has been conducted. The 5-axis highly dynamic laser precision machining centre Lasertec 80 Shape equipped with the nano-second pulsed ytterbium fibre laser and CNC system Siemens 840 D was used. The planar and spherical surfaces first prepared by turning have been textured. The regular array of spherical and ellipsoidal dimples with a different dimensions and different surface density has been created. Laser surface texturing has been realized under different combinations of process parameters: pulse frequency, pulse energy and laser beam scanning speed. The morphological characterization of ablated surfaces has been performed using scanning electron microscopy (SEM) technique. The results show limited possibility of ns pulse fibre laser application to generate different surface structures for tribological modification of metallic materials. These structures were obtained by varying the processing conditions between surface ablation, to surface remelting. In all cases the areas of molten material and re-cast layers were observed on the bottom and walls of the dimples. Beside the influence of laser beam parameters on the machined surface quality during laser machining of regular hemispherical and elipsoidal dimple texture on parabolic and hemispherical surfaces has been studied.

Effect of laser irradiation on the structural, morphological and electrical properties of polycrystalline TiO2 thin films

Science.gov (United States)

Khan, M. I.; Ali, Asghar

TiO2 thin film is deposited on glass substrate by sol-gel dip coating technique. After deposition, films were irradiated by continuous wave (CW) diode laser at an angle of 45°. XRD shows both the anatase and brookite phases of TiO2. Nano particles of regular and control sizes are appeared in SEM micrographs. Therefore, shape and size of nano particles can be control by using Laser irradiation. The average sheet resistivity of TiO2 thin film irradiated by 0, 2, 4 and 6 min are 6.72 × 105, 5.32 × 105, 3.44 × 105 and 4.95 × 105 (ohm-m) respectively, according to four point probe.

Three-dimensional analysis of somatic mitochondrial dynamics in fission-deficient injured motor neurons using FIB/SEM.

Science.gov (United States)

Tamada, Hiromi; Kiryu-Seo, Sumiko; Hosokawa, Hiroki; Ohta, Keisuke; Ishihara, Naotada; Nomura, Masatoshi; Mihara, Katsuyoshi; Nakamura, Kei-Ichiro; Kiyama, Hiroshi

2017-08-01

Mitochondria undergo morphological changes through fusion and fission for their quality control, which are vital for neuronal function. In this study, we examined three-dimensional morphologies of mitochondria in motor neurons under normal, nerve injured, and nerve injured plus fission-impaired conditions using the focused ion beam/scanning electron microscopy (FIB/SEM), because the FIB/SEM technology is a powerful tool to demonstrate both 3D images of whole organelle and the intra-organellar structure simultaneously. Crossing of dynamin-related protein 1 (Drp1) gene-floxed mice with neuronal injury-specific Cre driver mice, Atf3:BAC Tg mice, allowed for Drp1 ablation specifically in injured neurons. FIB/SEM analysis demonstrated that somatic mitochondrial morphologies in motor neurons were not altered before or after nerve injury. However, the fission impairment resulted in prominent somatic mitochondrial enlargement, which initially induced complex morphologies with round regions and long tubular processes, subsequently causing a decrease in the number of processes and further enlargement of the round regions, which eventually resulted in big spheroidal mitochondria without processes. The abnormal mitochondria exhibited several degradative morphologies: local or total cristae collapse, vacuolization, and mitophagy. These suggest that mitochondrial fission is crucial for maintaining mitochondrial integrity in injured motor neurons, and multiple forms of mitochondria degradation may accelerate neuronal degradation. © 2017 Wiley Periodicals, Inc.

Nd:YAG laser annealing investigation of screen-printed CIGS layer on PET: Layer annealing method for photovoltaic cell fabrication process

KAUST Repository

Alsaggaf, Ahmed

2014-06-01

Cu(In, Ga)Se2 (CIGS) ink was formulated from CIGS powder, polyvinyl butyral PVB, terpineol and polyester/polyamine co-polymeric dispersant KD-1. Thin films with different thicknesses were deposited on PET substrate using screen-printing followed by heat treatment using a Nd:YAG laser. The structure and morphology of the heated thin films were studied. The characterization of the CIGS powder, ink, and film was done using TGA, SEM, FIB, EDS, and XRD. TGA analysis shows that the CIGS ink is drying at 200 °C, which is well below the decomposition temperature of the PET substrate. It was observed by SEM that 20 pulses of 532nm and 60 mJ/cm2 Nd:YAG laser annealing causes atomic diffusion on the near surface area. Furthermore, FIB cross section images were utilized to monitor the effect of laser annealing in the depth of the layer. Laser annealing effects were compared to as deposited layer using XRD in reference to CIGS powder. The measurement shows that crystallinity of deposited CIGS is retained while EDS quantification and atomic ratio result in gradual loss of selenium as laser energy increases. The laser parameters were tuned in an effort to utilize laser annealing of screen-printed CIGS layer as a layer annealing method for solar cell fabrication process.

Determination of morphological features and molecular interactions ...

African Journals Online (AJOL)

This research focused on identifying the morphological features and molecular interactions of the Nigerian Bentonitic clays using Scanning Electron Microscope (SEM) characterisation technique. The SEM microstructure images indicated that the bentonite samples are generally moderately dispersive to dispersive with ...

ZnO synthesized in air by fs laser irradiation on metallic Zn thin films

Science.gov (United States)

Esqueda-Barrón, Y.; Herrera, M.; Camacho-López, S.

2018-05-01

We present results on rapid femtosecond laser synthesis of nanostructured ZnO. We used metallic Zn thin films to laser scan along straight tracks, until forming nanostructured ZnO. The synthesis dependence on laser irradiation parameters such as the per pulse fluence, integrated fluence, laser scan speed, and number of scans were explored carefully. SEM characterization showed that the morphology of the obtained ZnO is dictated by the integrated fluence and the laser scan speed; micro Raman and XRD results allowed to identify optimal laser processing conditions for getting good quality ZnO; and cathodoluminescence measurements demonstrated that a single laser scan at high per pulse laser fluence, but a medium integrated laser fluence and a medium laser scan speed favors a low density of point-defects in the lattice. Electrical measurements showed a correlation between resistivity of the laser produced ZnO and point-defects created during the synthesis. Transmittance measurements showed that, the synthesized ZnO can reach down to the supporting fused silica substrate under the right laser irradiation conditions. The physical mechanism for the formation of ZnO, under ultrashort pulse laser irradiation, is discussed in view of the distinct times scales given by the laser pulse duration and the laser pulse repetition rate.

Pulsed Laser deposition of Al2O3 thin film on silicon

International Nuclear Information System (INIS)

Lamagna, A.; Duhalde, S.; Correra, L.; Nicoletti, S.

1998-01-01

Al 2 O 3 thin films were fabricated by pulsed laser deposition (PLD) on Si 3 N 4 /Si, to improve the thermal and electrical isolation of gas sensing devices. The microstructure of the films is analysed as a function of the deposition conditions (laser fluence, oxygen pressure, target-substrate distance and substrate temperature). X-ray analysis shows that only a sharp peak that coincides with the corundum (116) reflection can be observed in all the films. But, when they are annealed at temperatures above 1,200 degree centigrade, a change in the crystalline structure of some films occurs. The stoichiometry and morphology of the films with and without thermal treatment are compared using environmental scanning electron microscopy (SEM) and EDAX analysis. (Author) 14 refs

Microstructure and mechanical characteristics of laser coating-texturing alloying dimples

International Nuclear Information System (INIS)

Wan Daping; Chen Bingkui; Shao Yimin; Wang Shilong; Hu Dejin

2008-01-01

A novel laser coating-texturing (LCT) technique was proposed to achieve appropriate surface topographies and frictional behaviour. The LCT process was realized by applying laser pulses at very high repetition rate to produce innumerable micro-craters with required shape profile on the surface of the workpiece. Moreover, surface alloying of the dimples was carried out by melting submicron WC-TiC-Co alloy powder on the substrates. Morphology and microstructures of the texturing layers were characterised using optical microscopy (OM), scanning electron microscopy (SEM), and X-ray diffraction (XRD). Mechanical properties of the textured samples were evaluated by abrasive resistance tests and microhardness measurement. Experimental results show that good fusion bonding between the texturing layers and the substrate has been formed, and the texturing layers are mainly composed of dense and hard fine-grained structures. The abrasive wear resistance of the laser coating-textured surface was 10 times higher than that of the substrates. The average surface microhardness values were as high as 830 HV.

Lithium niobate bulk crystallization promoted by CO2 laser radiation

Science.gov (United States)

Ferreira, N. M.; Costa, F. M.; Nogueira, R. N.; Graça, M. P. F.

2012-09-01

The crystallization induced by laser radiation is a very promising technique to promote glass/ceramic transformation, being already used to produce crystalline patterns on glass surfaces. In this work, a SiO2-Li2O-Nb2O5 glass, prepared by the sol-gel route, was submitted to CO2 laser radiation and conventional heat-treatments in order to induce the LiNbO3 crystallization. The structure and morphology of the samples prepared by both routes was analyzed as a function of exposure time, radiation power and heat-treatment temperatures by XRD, Raman spectroscopy and SEM. The results reveal a correlation between the crystallization degree of LiNbO3 particles and glass matrix with the heat treatment type and experimental parameters. An heat-treatment at 650 °C/4 h was necessary to induce crystallization in heat treatments samples while 4 W/500 s was enough for laser radiation ones, corresponding a reduction time processing of ˜14 000 s.

Structural and optical properties of colloidal InZnO NPs prepared by laser ablation in liquid

Science.gov (United States)

khlewee, Maryam M.; Khashan, Khawla S.

2018-05-01

In the current work, colloidal of InZnO NPs were produced by pulsed laser ablation in liquid (PLAL) method. The effect of indium content on the structural, morphological and optical of the InZnO NPs was confirmed by Fourier transform infrared spectroscopy, Scanning electron microscopy, and UV-visible spectroscopy. The FTIR spectra showed the presence of the metal-oxide bond. The SEM exhibit different morphological aspects according to the (In/Zn) ratio. The optical transmittance of InZnO NPs has high value around 70 % in the visible region and the band gap value was varied between 3.29 to 3.25 eV.

Surface Morphology and Bending Deformation of 2024-T3 Thin Sheets with Laser Peen Forming

Directory of Open Access Journals (Sweden)

Wu Junfeng

2018-01-01

Full Text Available Laser peen forming (LPF is a pure mechanical forming method through accumulated plastic strain, which has been successfully applied in wing components. Experimental investigation has been performed to understand the effect of process parameters such as constraint conditions, sheet thickness and laser energy on surface morphology and bending deformation of 2024-T3 thin sheets of dimensions of 76 mm ×19 mm (length × width. The research results indicated that bulges on the aluminum foil were generated at the bottom surface and not generated at the topmost surface. It was different for transition value of two-way bending deformations of thin sheets after LPF with different constraint conditions. Remain flat thicknesses of thin sheets after LPF were about 1 mm ~ 2 mm for 20 J, 25 J and 30 J. Arc heights and curvatures of 3 mm thickness sheets increased with laser energy and those of 2 mm thickness sheets only made little change. It was found that convex deformation, flat, concave deformation and laser deep drawing for thin sheets with different thicknesses after LPF.

Using a laser measurement system for monitoring morphological changes on the Strug rock fall, Slovenia

Directory of Open Access Journals (Sweden)

M. Mikoš

2005-01-01

Full Text Available A medium-ranged high performance handheld reflectorless laser measurement system, was used for a morphological survey on the Strug rock fall in W Slovenia in the period from August 2003 to August 2004. The purpose was to evaluate its potential for monitoring ground surface changes in rock fall source areas and to help evaluating morphological changes by measuring distance from fixed points. In the area, 21 fixed geodetic points have been established. Altogether, seven measurement sets with more than 5500 points have been gathered in the rock fall area. Choosing a point cloud with a density of less than 1 point per 10m2 on a very rough rock fall surface failed to be a good solution. The changes on larger areas were shown by displacements of selected significantly large-sized rock blocks with a volume of several m3. Because only smaller changes were observed between the single field series, the rock fall surface generally remained unchanged. Local surface changes of the order of 1 m or more, were clearly shown by measurements in the selected referenced cross sections. The usage of these cross sections gave a possibility to evaluate volumetric changes on the surface. The laser measurement system provided a good replacement for the classical terrestrial geodetic survey equipment, especially when performing remote monitoring of morphological changes in rock fall hazard zones, however, the case is different when fixed points are to be measured precisely.

KrF laser ablation of a polyethersulfone film: Effect of pulse duration on structure formation

International Nuclear Information System (INIS)

Pazokian, Hedieh; Selimis, Alexandros; Stratakis, Emmanuel; Mollabashi, Mahmoud; Barzin, Jalal; Jelvani, Saeid

2011-01-01

Polyethersulfone (PES) films were processed with KrF laser irradiation of different pulse durations (τ). Scanning electron microscopy (SEM) and Raman spectroscopy were employed for the examination of the morphology and chemical composition of the irradiated surfaces, respectively. During ablation with 500 fs and 5 ps pulses, localized deformations (beads), micro-ripple and conical structures were observed on the surface depending on the irradiation fluence (F) and the number of pulses (N). In addition, the number density of the structures is affected by the irradiation parameters (τ, F, N). Furthermore, at longer pulse durations (τ = 30 ns), conical structures appear at lower laser fluence values, which are converted into columnar structures upon irradiation at higher fluences. The Raman spectra collected from the top of the structures following irradiation at different pulse durations revealed graphitization of the ns laser treated areas, in contrast to those processed with ultra-short laser pulses.

Laser sintering of magnesia with nanoparticles of iron oxide and aluminum oxide

International Nuclear Information System (INIS)

García, L.V.; Mendivil, M.I.; Roy, T.K. Das; Castillo, G.A.; Shaji, S.

2015-01-01

Highlights: • Laser sintered MgO pellets with nanoparticles of Al 2 O 3 and Fe 2 O 3 . • Characterized these pellets by XRD, SEM and XPS. • Spinel formations were observed in both cases. • Changes in morphology and structure were analyzed. - Abstract: Nanoparticles of iron oxide (Fe 2 O 3 , 20–40 nm) and aluminum oxide (Al 2 O 3 , 50 nm) were mixed in different concentrations (3, 5 and 7 wt%) in a magnesium oxide (MgO) matrix. The mixture pellet was irradiated with 532 nm output from a Q-switched Nd:YAG laser using different laser fluence and translation speed for sintering. The refractory samples obtained were analyzed using X-ray diffraction technique, scanning electron microscopy and X-ray photoelectron spectroscopy. The results showed that the samples irradiated at translation speed of 110 μm/s and energy fluence of 1.7 J/cm 2 with a concentration of 5 and 7 wt% of Fe 2 O 3 presented the MgFe 2 O 4 spinel-type phase. With the addition of Al 2 O 3 nanoparticles, at a translation speed of 110 μm/s and energy fluence of 1.7 J/cm 2 , there were the formations of MgAl 2 O 4 spinel phase. The changes in morphologies and microstructure due to laser irradiation were analyzed

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.

Science.gov (United States)

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.

Surface characteristics of isopod digestive gland epithelium studied by SEM.

Science.gov (United States)

Millaku, Agron; Leser, Vladka; Drobne, Damjana; Godec, Matjaz; Torkar, Matjaz; Jenko, Monika; Milani, Marziale; Tatti, Francesco

2010-05-01

The structure of the digestive gland epithelium of a terrestrial isopod Porcellio scaber has been investigated by conventional scanning electron microscopy (SEM), focused ion beam-scanning electron microscopy (FIB/SEM), and light microscopy in order to provide evidence on morphology of the gland epithelial surface in animals from a stock culture. We investigated the shape of cells, extrusion of lipid droplets, shape and distribution of microvilli, and the presence of bacteria on the cell surface. A total of 22 animals were investigated and we found some variability in the appearance of the gland epithelial surface. Seventeen of the animals had dome-shaped digestive gland "normal" epithelial cells, which were densely and homogeneously covered by microvilli and varying proportions of which extruded lipid droplets. On the surface of microvilli we routinely observed sparsely distributed bacteria of different shapes. Five of the 22 animals had "abnormal" epithelial cells with a significantly altered shape. In three of these animals, the cells were much smaller, partly or completely flat or sometimes pyramid-like. A thick layer of bacteria was detected on the microvillous border, and in places, the shape and size of microvilli were altered. In two animals, hypertrophic cells containing large vacuoles were observed indicating a characteristic intracellular infection. The potential of SEM in morphological investigations of epithelial surfaces is discussed.

In vitro study of morphological and chemical modification threshold of bovine dental enamel irradiated by the holmium laser

International Nuclear Information System (INIS)

Eduardo, Patricia Lerro de Paula

2001-01-01

The aim of this study is to investigate the Ho:YLF laser effects on the dental enamel surface with regards to its morphology, thermal variations during its irradiation in the pulp chamber and its increased resistance to demineralization through quantitative analysis of calcium and phosphorous atoms reactive concentrations in samples. Twenty samples of bovine enamel were used and divided in four groups: control - acidulated phosphate fluoride (APF) application followed by demineralization treatment with lactic acid; irradiation with Ho:YLF laser (100 J/cm 2 ) followed by APF topic application and demineralization treatment with lactic acid; irradiation with Ho:YLF laser (350 J/cm 2 ) followed by APF topic application and demineralization treatment with lactic acid: and irradiation with Ho:YLF laser ( 450 J/cm 2 ) followed by APF topic application and demineralization treatment with lactic acid. Ali samples were quantified according to their calcium and phosphorous atoms relative concentrations before and after the treatments above. X-Ray fluorescence spectrochemical analysis and scanning electron microscopy were carried out. It was observed an increase on the calcium and phosphorous atoms concentration ratio and therefore the enamel demineralization reduction as a result of the lactic acid treatment in the samples irradiated with the holmium laser followed by the APF application. In order to evaluate the feasibility of this study for clinical purposes, morphological changes caused by the holmium laser irradiation were analyzed. Such modifications were characterized by melted and re-solidified regions of the enamel with consequent changes on its permeability and solubility. Temperature changes of ten human pre-molars teeth irradiated with 350 J/cm 2 and 450 J/cm 2 were also monitored in the pulp chamber in real time. Temperature increases over 4,20 C did not occur. The results obtained from this study along with the results from previous researches developed at

Morphological Changes Of The Root Surface And Fracture Resistance After Treatment Of Root Fracture By CO2 Laser And Glass Ionomer Or Mineral Trioxide Aggregates

Science.gov (United States)

Badr, Y. A.; Abd El-Gawad, L. M.; Ghaith, M. E.

2009-09-01

This in vitro study evaluates the morphological changes of the root surface and fracture resistance after treatment of root cracks by CO2 laser and glass Ionomer or mineral trioxide aggregates (MTA). Fifty freshly extracted human maxillary central incisor teeth with similar dimension were selected. Crowns were sectioned at the cemento-enamel junction, and the lengths of the roots were adjusted to 13 mm. A longitudinal groove with a dimension of 1×5 mm2 and a depth of 1.5 mm was prepared by a high speed fissure bur on the labial surface of the root. The roots were divided into 5 groups: the 10 root grooves in group 1 were remained unfilled and were used as a control group. The 10 root grooves in group 2 were filled with glass Ionomer, 10 root grooves in group 3 were filled with MTA, the 10 root grooves in group 4 were filled with glass Ionomer and irradiated by CO2 laser and the 10 root grooves in group 5 were filled with MTA and irradiated with CO2 laser. Scanning electron microscopy was performed for two samples in each group. Tests for fracture strength were performed using a universal testing machine and a round tip of a diameter of 4 mm. The force was applied vertically with a constant speed of 1 mm min 1. For each root, the force at the time of fracture was recorded in Newtons. Results were evaluated statistically with ANOVA and Turkey's Honestly Significant Difference (HSD) tests. SEM micrographs revealed that the melted masses and the plate-like crystals formed a tight Chemical bond between the cementum and glass Ionomer and melted masses and globular like structure between cementum and MTA. The mean fracture resistance was the maximum fracture resistance in group 5 (810.8 N). Glass Ionomer and MTA with the help of CO2 laser can be an alternative to the treatment of tooth crack or fracture. CO2 laser increase the resistance of the teeth to fracture.

Pulsed-laser deposition of smooth thin films of Er, Pr and Nd doped glasses

Energy Technology Data Exchange (ETDEWEB)

Epurescu, G. [National Institute for Laser, Plasma and Radiation Physics, Atomistilor 409, P.O. Box MG 16, RO- 77125, Bucharest-Magurele (Romania)], E-mail: george@nipne.ro; Vlad, A. [National Institute for Laser, Plasma and Radiation Physics, Atomistilor 409, P.O. Box MG 16, RO- 77125, Bucharest-Magurele (Romania); Institut fuer Angewandte Physik, Johannes-Kepler-Universitaet Linz, A-4040 Linz (Austria); Bodea, M.A. [Institut fuer Angewandte Physik, Johannes-Kepler-Universitaet Linz, A-4040 Linz (Austria); Vasiliu, C. [National Institute for Optoelectronics INOE 2000, Atomistilor 1, P.O. Box MG 05, 077125 Bucharest-Magurele (Romania); Dumitrescu, O. [University Politehnica of Bucharest, Faculty of Industrial Chemistry, Science and Engineering of Oxide Materials Department, Polizu Str. 1, sect. 1, Bucharest (Romania); Niciu, H. [National Institute of Glass, Department for Laser Glass Technology, 47 Th. Pallady Str., Sect.3, Bucharest (Romania); Elisa, M. [National Institute for Optoelectronics INOE 2000, Atomistilor 1, P.O. Box MG 05, 077125 Bucharest-Magurele (Romania); Siraj, K.; Pedarnig, J.D.; Baeuerle, D. [Institut fuer Angewandte Physik, Johannes-Kepler-Universitaet Linz, A-4040 Linz (Austria); Filipescu, M.; Nedelcea, A. [National Institute for Laser, Plasma and Radiation Physics, Atomistilor 409, P.O. Box MG 16, RO- 77125, Bucharest-Magurele (Romania); Galca, A.C. [National Institute of Materials Physics, Atomistilor 105bis, P.O. Box MG 07, RO- 77125, Magurele (Romania); Grigorescu, C.E.A. [National Institute for Optoelectronics INOE 2000, Atomistilor 1, P.O. Box MG 05, 077125 Bucharest-Magurele (Romania); Dinescu, M. [National Institute for Laser, Plasma and Radiation Physics, Atomistilor 409, P.O. Box MG 16, RO- 77125, Bucharest-Magurele (Romania)

2009-03-01

Thin films of complex oxides have been obtained by pulsed-laser deposition (PLD) from glass targets belonging to the system Li{sub 2}O-Al{sub 2}O{sub 3}-P{sub 2}O{sub 5}-(RE){sub 2}O{sub 3}, with RE = Nd, Pr, Er. The films were deposited on quartz, silicon and ITO/glass substrates using a F{sub 2} laser ({lambda} = 157 nm, {iota} {approx} 20 ns) for ablation in vacuum. The structural, morphological and optical properties of the oxide films were investigated through IR and UV-VIS spectroscopy, Atomic Force Microscopy (AFM), Scanning Electron Microscopy, Energy Dispersive X-ray Spectroscopy (SEM-EDX) and Spectroscopic Ellipsometry. The laser wavelength was found to be the key parameter to obtain thin films with very smooth surface. In this way new possibilities are opened to grow multilayer structures for photonic applications.

Laser reflection spot as a pattern in a diamond coating – a microscopic study

Directory of Open Access Journals (Sweden)

GORDANA S. RISTIĆ

2009-07-01

Full Text Available Diamond coatings were deposited by the synchronous and coupled action of a hot filament CVD method and a pulsed CO2 laser in spectro-absorbing and spectro-non-absorbing diamond precursor atmospheres. The obtained coatings were structured/patterned, i.e., they were comprised of uncovered, bare locations. An extra effect observed only in the spectro-active diamond precursor atmosphere was the creation of another laser spot in the coating – a reflection spot. In order to establish the practical usability of the latter one, extensive microscopic investigations were performed with consideration of the morphology changes in the spot of the direct laser beam. Normal incidence SEM images of this spot showed a smooth surface, without any pulse radiation damage. AFM imaging revealed the actual surface condition and gave precise data on the surface characteristics.

Laser-Based Surface Modification of Microstructure for Carbon Fiber-Reinforced Plastics

Science.gov (United States)

Yang, Wenfeng; Sun, Ting; Cao, Yu; Li, Shaolong; Liu, Chang; Tang, Qingru

2018-05-01

Bonding repair is a powerful feature of carbon fiber-reinforced plastics (CFRP). Based on the theory of interface bonding, the interface adhesion strength and reliability of the CFRP structure will be directly affected by the microscopic features of the CFRP surface, including the microstructure, physical, and chemical characteristics. In this paper, laser-based surface modification was compared to Peel-ply, grinding, and polishing to comparatively evaluate the surface microstructure of CFRP. The surface microstructure, morphology, fiber damage, height and space parameters were investigated by scanning electron microscopy (SEM) and laser confocal microscopy (LCM). Relative to the conventional grinding process, laser modification of the CFRP surface can result in more uniform resin removal and better processing control and repeatability. This decreases the adverse impact of surface fiber fractures and secondary damage. The surface properties were significantly optimized, which has been reflected such things as the obvious improvement of surface roughness, microstructure uniformity, and actual area. The improved surface microstructure based on laser modification is more conducive to interface bonding of CFRP structure repair. This can enhance the interfacial adhesion strength and reliability of repair.

Human cardiac telocytes: 3D imaging by FIB-SEM tomography.

Science.gov (United States)

Cretoiu, D; Hummel, E; Zimmermann, H; Gherghiceanu, M; Popescu, L M

2014-11-01

Telocyte (TC) is a newly identified type of cell in the cardiac interstitium (www.telocytes.com). TCs are described by classical transmission electron microscopy as cells with very thin and long telopodes (Tps; cellular prolongations) having podoms (dilations) and podomers (very thin segments). TCs' three-dimensional (3D) morphology is still unknown. Cardiac TCs seem to be particularly involved in long and short distance intercellular signalling and, therefore, their 3D architecture is important for understanding their spatial connections. Using focused ion beam scanning electron microscopy (FIB-SEM) we show, for the first time, the whole ultrastructural anatomy of cardiac TCs. 3D reconstruction of cardiac TCs by FIB-SEM tomography confirms that they have long, narrow but flattened (ribbon-like) telopodes, with humps generated by the podoms. FIB-SEM tomography also confirms the network made by TCs in the cardiac interstitium through adherens junctions. This study provides the first FIB-SEM tomography of a human cell type. © 2014 The Authors. Journal of Cellular and Molecular Medicine published by John Wiley & Sons Ltd and Foundation for Cellular and Molecular Medicine.

Laser assisted removal of synthetic painting-conservation materials using UV radiation of ns and fs pulse duration: Morphological studies on model samples

International Nuclear Information System (INIS)

Pouli, P.; Nevin, A.; Andreotti, A.; Colombini, P.; Georgiou, S.; Fotakis, C.

2009-01-01

In an effort to establish the optimal parameters for the cleaning of complex layers of polymers (mainly based on acrylics, vinyls, epoxys known as Elvacite, Laropal, Paraloid B72, among others) applied during past conservation treatments on the surface of wall paintings, laser cleaning tests were performed with particular emphasis on the plausible morphological modifications induced in the remaining polymeric material. Pulse duration effects were studied using laser systems of different pulse durations (ns and fs) at 248 nm. Prior to tests on real fragments from the Monumental Cemetery in Pisa (Italy) which were coated with different polymers, attention was focused on the study of model samples consisting of analogous polymer films cast on quartz disks. Ultraviolet irradiation is strongly absorbed by the studied materials both in ns and fs irradiation regimes. However, it is demonstrated that ultrashort laser pulses result in reduced morphological alterations in comparison to ns irradiation. In addition, the dependence of the observed alterations on the chemical composition of the consolidation materials in both regimes was examined. Most importantly, it was shown that in this specific conservation problem, an optimum cleaning process may rely not only on the minimization of laser-induced morphological changes but also on the exploitation of the conditions that favour the disruption of the adhesion between the synthetic material and the painting.

Surface morphology of polyethylene glycol films produced by matrix-assisted pulsed laser evaporation (MAPLE): Dependence on substrate temperature

DEFF Research Database (Denmark)

Rodrigo, K.; Czuba, P.; Toftmann, B.

2006-01-01

The dependence of the surface morphology on the substrate temperature during film deposition was investigated for polyethylene glycol (PEG) films by matrix-assisted pulsed laser evaporation (MAPLE). The surface structure was studied with a combined technique of optical imaging and AFM measurements...

The Effect of Nonnormality on CB-SEM and PLS-SEM Path Estimates

OpenAIRE

Z. Jannoo; B. W. Yap; N. Auchoybur; M. A. Lazim

2014-01-01

The two common approaches to Structural Equation Modeling (SEM) are the Covariance-Based SEM (CB-SEM) and Partial Least Squares SEM (PLS-SEM). There is much debate on the performance of CB-SEM and PLS-SEM for small sample size and when distributions are nonnormal. This study evaluates the performance of CB-SEM and PLS-SEM under normality and nonnormality conditions via a simulation. Monte Carlo Simulation in R programming language was employed to generate data based on the theoretical model w...

Microstructure and Properties of Laser Additive Manufacturing TC Bearing

Directory of Open Access Journals (Sweden)

YANG Jiao-xi

2016-07-01

Full Text Available In order to solve the problem of uneven wear of TC bearing that conventional method brought and improve its service life,wear-resistant coating was fabricated on the surface of steel parts matrix with the method of laser additive manufacture. The Cr3C2/Fe based alloy was deposited by laser cladding technique on the inner-sleeve cylindrical and outer-sleeve bore of TC bearing with two different process parameters. The high-performance coating was obtained respectively, of cracks free,no pores and with good metallurgical quality. The morphology of the laser cladding coating was observed by scanning electronic microscope (SEM,the composition was analyzed by EDS,the phase transformation was characterized by XRD. The wear resistance,corrosion resistance and hardness of the laser cladding layer were tested by friction and wear tester,salt spray test chamber and digital micro-hardness tester respectively. The results show that the average micro-hardness of composite coating is HV700. The wear resistance of the composite coating is about 3 times as much as the Ni-based alloy. The corrosion resistance is close to 316L stainless steel.

SEM Evaluation of Enamel Surface Changes and Enamel Microhardness around Orthodontic Brackets after Application of CO2 Laser, Er,Cr:YSGG Laser and Fluoride Varnish: An In vivo Study.

Science.gov (United States)

Kaur, Tarundeep; Tripathi, Tulika; Rai, Priyank; Kanase, Anup

2017-09-01

One of the most undesirable consequences of orthodontic treatment is occurrence of enamel demineralization around orthodontic brackets. Numerous in vitro studies have reported the prevention of enamel demineralization by surface treatment with lasers and fluoride varnish. To evaluate the changes on the enamel surface and microhardness around orthodontic brackets after surface treatment by CO 2 laser, Er, Cr:YSGG laser and fluoride varnish in vivo. A double blind interventional study was carried out on 100 premolars which were equally divided into five groups, out of which one was the control group (Group 0). The intervention groups (Group I to IV) comprised of patients requiring fixed orthodontic treatment with all 4 first premolars extraction. Brackets were bonded on all 80 premolars which were to be extracted. Enamel surface treatment of Groups I, II and III was done by CO 2 laser, Er, Cr:YSGG laser and 5% sodium fluoride varnish respectively and Group IV did not receive any surface treatment. A modified T-loop was ligated to the bracket and after two months, the premolars were extracted. Surface changes were evaluated by Scanning Electron Microscopic (SEM) and microhardness testing. Comparison of mean microhardness between all the groups was assessed using post-hoc test with Bonferroni correction. Group I showed a melted enamel appearance with fine cracks and fissures while Group II showed a glossy, homogenous enamel surface with well coalesced enamel rods. Group III showed slight areas of erosions and Group IV presented areas of stripped enamel. Significant difference was observed between the mean microhardness (VHN) of Group I, Group II, Group III, Group IV and Group 0 with p<0.001. A significant difference of p<0.001 was observed while comparing Group I vs II,III,IV,0 and Group II vs III,IV,0. However, difference while comparing Group III vs IV was p=0.005 and difference between the mean microhardness of Group 0 vs Group III was non significant. Surface

GaAs laser therapy reestablishes the morphology of the NMJ and nAChRs after injury due to bupivacaine.

Science.gov (United States)

Pissulin, Cristiane Neves Alessi; de Souza Castro, Paula Aiello Tomé; Codina, Flávio; Pinto, Carina Guidi; Vechetti-Junior, Ivan Jose; Matheus, Selma Maria Michelin

2017-02-01

Local anesthetics are used to relieve pre- and postoperative pain, acting on both sodium channels and nicotinic acetylcholine receptors (nAChR) at the neuromuscular junction (NMJ). Bupivacaine acts as a non-competitive antagonist and has limitations, such as myotoxicity, neurotoxicity, and inflammation. Low-level laser therapy (LLLT) has anti-inflammatory, regenerative, and analgesic effects. The aim of the present study was to evaluate the effects of a gallium arsenide laser (GaAs) on the morphology of the NMJ and nAChRs after application of bupivacaine in the sternomastoid muscle. Thirty-two adult male Wistar rats received injections of bupivacaine 0.5% (Bupi: right antimere) and 0.9% sodium chloride (Cl: left antimere). Next, the animals were divided into a Control group (C) and a Laser group (LLLT). The laser group received LLLT (GaAs 904nm, 50mW, 4,8J) in both antimeres for five consecutive days. After seven days, the animals were euthanized and the surface portion of the sternomastoid muscle was removed, frozen, and subjected to morphological and morphometric analyses of the NMJs (nonspecific esterase reaction), confocal laser scanning, and an ultrastructural analysis. The nAChRs were quantified by Western blotting. In the chloride group, the morphology and morphometry of the NMJs remained stable. The maximum diameters of the NMJs were lower in the Bupi (15.048±1.985) and LLLT/Bupi subgroups (15.456±1.983) compared to the Cl (18.502±2.058) and LLLT/Cl subgroups (19.356±2.522) (pbupivacaine, with recovery in the junctional folds and active zone. There was an increase in the perimeter of the LLLT/Bupi subgroup (150.33) compared to the Bupi subgroup (74.69) (pbupivacaine, providing important data supporting the use of LLLT in therapeutic protocols for injuries triggered by local anesthetics. Copyright © 2016 Elsevier B.V. All rights reserved.

Porous niobium coatings fabricated with selective laser melting on titanium substrates: Preparation, characterization, and cell behavior

Energy Technology Data Exchange (ETDEWEB)

Zhang, Sheng [Science and Technology on Power Beam Processes Laboratory, Beijing Aeronautical Manufacturing Technology Research Institute (BAMTRI), Beijing 100024 (China); State Key Lab of Materials Processing and Die & Mould Technology, Huazhong University of Science and Technology, Wuhan 430074 (China); Cheng, Xian; Yao, Yao; Wei, Yehui [Department of Stomatology, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430022 (China); Han, Changjun; Shi, Yusheng [State Key Lab of Materials Processing and Die & Mould Technology, Huazhong University of Science and Technology, Wuhan 430074 (China); Wei, Qingsong, E-mail: wqs_xn@163.com [State Key Lab of Materials Processing and Die & Mould Technology, Huazhong University of Science and Technology, Wuhan 430074 (China); Zhang, Zhen, E-mail: zhangzhentitanium@163.com [State Key Lab of Materials Processing and Die & Mould Technology, Huazhong University of Science and Technology, Wuhan 430074 (China); Department of Stomatology, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430022 (China)

2015-08-01

Nb, an expensive and refractory element with good wear resistance and biocompatibility, is gaining more attention as a new metallic biomaterial. However, the high price of the raw material, as well as the high manufacturing costs because of Nb's strong oxygen affinity and high melting point have limited the widespread use of Nb and its compounds. To overcome these disadvantages, porous Nb coatings of various thicknesses were fabricated on Ti substrate via selective laser melting (SLM), which is a 3D printing technique that uses computer-controlled high-power laser to melt the metal. The morphology and microstructure of the porous Nb coatings, which had pores ranging from 15 to 50 μm in size, were characterized with scanning electron microscopy (SEM). The average hardness of the coating, which was measured with the linear intercept method, was 392 ± 37 HV. In vitro tests of the porous Nb coating which was monitored with SEM, immunofluorescence, and CCK-8 counts of cells, exhibited excellent cell morphology, attachment, and growth. The simulated body fluid test also proved the bioactivity of the Nb coating. Therefore, these new porous Nb coatings could potentially be used for enhanced early biological fixation to bone tissue. In addition, this study has shown that SLM technique could be used to fabricate coatings with individually tailored shapes and/or porosities from group IVB and VB biomedical metals and their alloys on stainless steel, Co–Cr, and other traditional biomedical materials without wasting raw materials. - Highlights: • Porous Nb coating was firstly fabricated on Ti substrate by SLM technique. • Morphology, microstructure and hardness of the coating were characterized. • In vitro test of the coating showed good cell attachment, morphology and growth.

Porous niobium coatings fabricated with selective laser melting on titanium substrates: Preparation, characterization, and cell behavior

International Nuclear Information System (INIS)

Zhang, Sheng; Cheng, Xian; Yao, Yao; Wei, Yehui; Han, Changjun; Shi, Yusheng; Wei, Qingsong; Zhang, Zhen

2015-01-01

Nb, an expensive and refractory element with good wear resistance and biocompatibility, is gaining more attention as a new metallic biomaterial. However, the high price of the raw material, as well as the high manufacturing costs because of Nb's strong oxygen affinity and high melting point have limited the widespread use of Nb and its compounds. To overcome these disadvantages, porous Nb coatings of various thicknesses were fabricated on Ti substrate via selective laser melting (SLM), which is a 3D printing technique that uses computer-controlled high-power laser to melt the metal. The morphology and microstructure of the porous Nb coatings, which had pores ranging from 15 to 50 μm in size, were characterized with scanning electron microscopy (SEM). The average hardness of the coating, which was measured with the linear intercept method, was 392 ± 37 HV. In vitro tests of the porous Nb coating which was monitored with SEM, immunofluorescence, and CCK-8 counts of cells, exhibited excellent cell morphology, attachment, and growth. The simulated body fluid test also proved the bioactivity of the Nb coating. Therefore, these new porous Nb coatings could potentially be used for enhanced early biological fixation to bone tissue. In addition, this study has shown that SLM technique could be used to fabricate coatings with individually tailored shapes and/or porosities from group IVB and VB biomedical metals and their alloys on stainless steel, Co–Cr, and other traditional biomedical materials without wasting raw materials. - Highlights: • Porous Nb coating was firstly fabricated on Ti substrate by SLM technique. • Morphology, microstructure and hardness of the coating were characterized. • In vitro test of the coating showed good cell attachment, morphology and growth

(AN)AEROBIC BACTERIA FOUND IN SECONDARY-CATARACT MATERIAL - A SEM/TEM STUDY

NARCIS (Netherlands)

KALICHARAN, D; JONGEBLOED, WL; LOS, LI; WORST, JGF

1992-01-01

Twentyfour patients, who had marked reduction of vision due to secondary-cataract developed after an ECCE, were treated by surgical cleaning of the posterior lens capsule. During this procedure globular secondary-cataract material was removed and collected for morphological examination by SEM and

Quantitative Analysis of Micro-porosity of Eco-material by Using SEM Technique

Institute of Scientific and Technical Information of China (English)

ZHANG Ji-ru; LIU Yuan-zhi; LIU Zu-de

2004-01-01

Microstructure of the eco-material combining vegetation recovery with slope protection is important for determining plant-growing properties.Several techniques for analyzing the eco-material microstructure are presented,including the freeze-cut-drying method of preparing samples for scanning electronic microscopy (SEM),the SEM image processing technique and quantifying analysis method of the SEM images,and etc.The aggregates and pores in SEM images are identified using the different mathematics operators,and their effects are compared.The areas of aggregates and pores are obtained using the operator of morphology,and the influences of different thresholds in image segmentation are also discussed.The results show that the method,in which the variation of non-maximum grey-level gradient is limited,improves the effect of edge detections due to a weak distinction existing at the edge between the aggregates and pores in image.The determination of the threshold should combine the image characteristic with filling operation,so as to assure the precision of the image analysis,in which the contact-segmentation is the simplest and most effective method.The results also show that the pore areas in eco-materials are generally larger than those in the correlative soils,and their increment is large as soil fabric being fine.These differences are related to admixture of expansive perliticThe operator of morphology provides a new method for the image analysis of other porous material microstructure such as soils and concretes.

In vitro study of 960 nm high power diode laser applications in dental enamel, aided by the presence of a photoinitiator dye: scanning electron microscopy analysis; Estudo in vitro das aplicacoes do laser de diodo de alta potencia 960 nm em esmalte dentario, assistido por um fotoiniciador: analise de microscopia eletronica de varredura

Energy Technology Data Exchange (ETDEWEB)

Oliveira, Marcelo Vinicius de

2002-06-15

The objective of this study is to verify if a high power diode laser can effectively modify the morphology of an enamel surface, and if this can be done in a controlled fashion by changing the lasers parameters. Previous studies using SEM demonstrated that through irradiation with Nd:YAG laser (1064 nm) it is possible to modify the morphology of the dental surface in such way as to increase its resistance against caries decays. The desired procedures that should achieve a decrease of the index of caries decays and of its sequels are on a primary level, which means that action is necessary before the disease installs itself. In this study it was used for the first time a prototype of a high power diode laser operating at 960 nm, produced by the Laboratory of Development of Lasers of the Center for Lasers and Applications of the IPEN. This equipment can present several advantages as reliability, reduced size and low cost. The aim was establish parameters of laser irradiation that produce the desired effects wanted in the enamel and protocols that guarantee its safety during application in dental hard tissues, protecting it of heating effects such as fissures and carbonization. (author)

Characterization of some biological specimens using TEM and SEM

Science.gov (United States)

Ghosh, Nabarun; Smith, Don W.

2009-05-01

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

MORPHOLOGICAL ASPECTS OF HUMAN LENS CAPSULES - A COMPARATIVE LM, SEM AND TEM EXAMINATION

NARCIS (Netherlands)

JONGEBLOED, WL; KALICHARAN, D; LOS, LI; VANDERVEEN, G; WORST, JGF

1991-01-01

Lens capsules of patients of advanced age, obtained after extracapsular cataract surgery, were carefully prepared for a combined LM, TEM and SEM investigation, after preliminary washing and mounting onto a holder in a buffer solution. After pre-fixation with GA, samples were postfixed for LM/TEM and

SEM observations of particle track membrane surfaces modificated using plasma treatment

International Nuclear Information System (INIS)

Sartowska, B.; Buczkowski, M.; Starosta, W.

2003-01-01

This work presents results of scanning electron microscopy (SEM) observations of 0.4 μm membranes after plasma treatment with different parameters. The morphology changes at the surfaces and at the pore walls were observed. The character of changes in the membrane parameters according to the process conditions was determined

Effect of fluence and ambient environment on the surface and structural modification of femtosecond laser irradiated Ti

International Nuclear Information System (INIS)

Umm-i-Kalsoom; Ali, Nisar; Husinsky, Wolfgang; Nathala, Chandra S R; Bashir, Shazia; Shahid Rafique, M; Makarov, Sergey V; Begum, Narjis

2016-01-01

Under certain conditions, ultrafast pulsed laser interaction with matter leads to the formation of self-organized conical as well as periodic surface structures (commonly reffered to as, laser induced periodic surface structures, LIPSS). The purpose of the present investigations is to explore the effect of fsec laser fluence and ambient environments (Vacuum and O 2 ) on the formation of LIPSS and conical structures on the Ti surface. The surface morphology was investigated by scanning electron microscope (SEM). The ablation threshold with single and multiple (N = 100) shots and the existence of an incubation effect was demonstrated by SEM investigations for both the vacuum and the O 2 environment. The phase analysis and chemical composition of the exposed targets were performed by x-ray diffraction (XRD) and energy dispersive x-ray spectroscopy (EDS), respectively. SEM investigations reveal the formation of LIPSS (nano and micro). FFT d-spacing calculations illustrate the dependence of periodicity on the fluence and ambient environment. The periodicity of nano-scale LIPSS is higher in the case of irradiation under vacuum conditions as compared to O 2 . Furthermore, the O 2 environment reduces the ablation threshold. XRD data reveal that for the O 2 environment, new phases (oxides of Ti) are formed. EDS analysis exhibits that after irradiation under vacuum conditions, the percentage of impurity element (Al) is reduced. The irradiation in the O 2 environment results in 15% atomic diffusion of oxygen. (paper)

Study on surface properties of gilt-bronze artifacts, after Nd:YAG laser cleaning

Energy Technology Data Exchange (ETDEWEB)

Lee, Hyeyoun [Division of Restoration Technology, National Research Institute of Cultural Heritage, Daejeon (Korea, Republic of); Cho, Namchul, E-mail: nam1611@hanmail.net [Department of Cultural Heritage Conservation Science, Kongju National University, Gongju, 314-701 (Korea, Republic of); Lee, Jongmyoung [Laser Engineering Group, IMT Co. Ltd, Gyeonggi (Korea, Republic of)

2013-11-01

As numerous pores are formed at plating gilt-bronze artifacts, the metal underlying the gold is corroded and corrosion products are formed on layer of gold. Through this study, the surfaces of gilt-bronze are being investigated before and after the laser irradiation to remove corrosion products of copper by using Nd:YAG laser. For gilt-bronze specimens, laser and chemical cleaning were performed, and thereafter, surface analysis with SEM-EDS, AFM, and XPS were used to determine the surface characteristics. Experimental results show that chemical cleaning removes corrosion products of copper through dissolution but it was not removed uniformly and separated the metal substrate and the gold layer. Nevertheless, through laser cleaning, some of the corrosions were removed with some damaged areas due to certain conditions and brown residues remained. Brown residues were copper corrosion products mixed with soil left within the gilt layer. It was due to surface morphology of uneven and rough gilt layer. Hence, they did not react effectively to laser beams, and thus, remained as residues. The surface properties of gilt-bronze should be thoroughly investigated with various surface analyses to succeed in laser cleaning without damages or residues.

Oxidation properties of laser clad Nb-Al alloys

International Nuclear Information System (INIS)

Tewari, S.K.; Mazumder, J.

1992-01-01

This paper reports on laser cladding parameters for non-equilibrium synthesis for several ternary and complex Nb-Al base alloys containing Ti, Cr, Si, Ni, B and C that have been established. Phase transformations occurring below 1500 degrees C have been determined using differential thermal analysis. Ductility of the clads is qualitatively evaluated from the extent of cracking around the microhardness indentations. Oxidation resistance of the clads in flowing air is measured at 800 degrees C, 1200 degrees C and 1400 degrees C and parabolic rate constants are calculated. Microstructure of the clads is studied using optical and scanning electron microscopes. X-ray diffraction and EDX techniques are used for identification of the oxides formed and the phases formed in as clad material. Oxide morphology is studied using SEM. Effect of alloying additions on the ductility and oxidation resistance of the laser clad Nb-Al alloys is discussed. The results are compared with those reported in literature for similar alloys produced by conventional processing methods

Morphological change study on root surfaces treated with curettes, sonic instruments or Er:YAG laser

International Nuclear Information System (INIS)

Guimaraes Filho, Arlindo Lopes

2004-01-01

Periodontal disease is caused by dental plaque and dental calculus on roots surfaces, specially on cervical areas. As dental plaque is the main cause and dental calculus a secondary one, it is practically impossible to separate one factor to the other one. In order to get periodontal tissue health it is necessary to eliminate dental plaque and calculus from root surfaces. In this sense, Er:YAG laser comes in as an excellent way to control periodontal disease, not only, by removing calculus and dental plaque but also for its bacteria reduction. The aim of this study is to compare, by S.E.M., root surfaces changing when they are treated with curettes and ultrasonic scaling or Er:YAG laser irradiation with two different energy levels of 60 mJ/pulse and 100 mJ/pulse and repetition tax of 10 Hz (in the display). It is also objective of this study to check a possible thermic damage to pulp tissue when the roots surfaces are irradiated with Er:YAG laser. We used for this study, five human dental roots, each one of them were cut into four samples, giving us a total of twenty samples, which were divided in five groups of four samples each one. The control group, we did not indicated any kind of treatment. The first group, the roots samples were scaled and planned with Gracey curettes 5/6 and 7/8. The second group, the roots samples were treated with ultrasonic instruments. The third group was irradiated with Er:YAG laser using 60 mJ/pulse , 10 Hz and energy density of 4 J/cm 2 (approximated). The fourth group was irradiated with Er:YAG laser using 100 mJ/pulse, 10 Hz and energy density of 7 J/cm 2 (approximated). The results analysis showed that roots scaling either with Gracey curettes or with ultrasonic instruments created smear layer covering roots surfaces; roots surfaces irradiated with Er:YAG laser showed few roughness in the third group; roots surfaces irradiated with Er:YAG laser showed no smear layer and the Er:YAG laser irradiation did not bring any thermic damage

Effect of liquid environment on the titanium surface modification by laser ablation

Energy Technology Data Exchange (ETDEWEB)

Ali, Nisar, E-mail: chnisarali@gmail.com [Laser Laboratories, Institute for Applied Physics, Vienna University of Technology, 1040 Vienna (Austria); Department of Basic Science and Humanities, University of Engineering and Technology Lahore, Faisalabad Campus, Faisalabad (Pakistan); Laser Laboratories, Centre for Advanced Studies in Physics, GC University, 1-Church Road, Lahore (Pakistan); Department of Physics, GC University, Kachehri Road, Lahore (Pakistan); Bashir, Shazia [Laser Laboratories, Centre for Advanced Studies in Physics, GC University, 1-Church Road, Lahore (Pakistan); Umm-i-Kalsoom [Laser Laboratories, Institute for Applied Physics, Vienna University of Technology, 1040 Vienna (Austria); Laser Laboratories, Centre for Advanced Studies in Physics, GC University, 1-Church Road, Lahore (Pakistan); Department of Physics, GC University, Kachehri Road, Lahore (Pakistan); Department of Basic Science and Humanities, University of Engineering and Technology Lahore, Kala Shah Kaku Campus, Lahore (Pakistan); Begum, Narjis [Department of Physics, COMSATS Institute of Information Technology, Islamabad (Pakistan); Rafique, Muhammad Shahid [Department of Physics, University of Engineering and Technology Lahore (Pakistan); Husinsky, Wolfgang [Laser Laboratories, Institute for Applied Physics, Vienna University of Technology, 1040 Vienna (Austria)

2017-05-31

Highlights: • Liquid assisted ablation effects on the titanium under varying number of laser pulses is investigated. • SEM analysis reveals the growth of various features like ripples, dendritic structures, pores, grains and craters. • Raman and XRD analyses shows the presence of TiO{sub 2} & TiH in both media whereas, TiC, TiCxOy are only identified in propanol. • Hardness of ablated Ti explored by Nano indentation is found to decrease with increasing number of pulses in both media. • Relationship between surface, structural and mechanical modifications is established. - Abstract: The effect of liquid environment (de-ionized water and propanol) on surface, structural and mechanical properties of femtosecond laser ablated titanium has been investigated. For this purpose, Ti: sapphire laser (800 nm, 30 fs, 1 kHz) has been employed, at a fluence of 3.6 J/cm{sup 2} in ambient environments of de-ionized water, and propanol for various number of laser pulses i.e. 500, 1000, 1500 and 2000. The surface features, chemical composition, structural analysis and mechanical properties of irradiated targets have been evaluated by using Scanning Electron Microscope (SEM), Energy Dispersive X-Ray Spectroscopy (EDS), X -ray Diffraction (XRD), Raman Spectroscopy and Nano-hardness tester. Various features like dendritic structures, globules, porous granular morphology, cones, crater, circular ripples and thermal stress cracking are observed at the ablated area after irradiation. These features are instigated by various thermal and chemical phenomena induced by laser heating at the solid–liquid interface. Decrease in nano-hardness observed in both ambient environments is attributable to the formation of hydrides after irradiation in both media.

Morphological Characteristics of Au Films Deposited on Ti: A Combined SEM-AFM Study

Directory of Open Access Journals (Sweden)

Francesco Ruffino

2018-03-01

Full Text Available Deposited Au films and coatings are, nowadays, routinely used as active or passive elements in several innovative electronic, optoelectronic, sensing, and energy devices. In these devices, the physical properties of the Au films are strongly determined by the films nanoscale structure. In addition, in these devices, often, a layer of Ti is employed to promote adhesion and, so, influencing the nanoscale structure of the deposited Au film. In this work, we present experimental analysis on the nanoscale cross-section and surface morphology of Au films deposited on Ti. In particular, we sputter-deposited thick (>100 nm thickness Au films on Ti foils and we used Scanning Electron Microscopy to analyze the films cross-sectional and surface morphology as a function of the Au film thickness and deposition angle. In addition, we analyzed the Au films surface morphology by Atomic Force Microscopy which allowed quantifying the films surface roughness versus the film thickness and deposition angle. The results establish a relation between the Au films cross-sectional and surface morphologies and surface roughness to the film thickness and deposition angle. These results allow setting a general working framework to obtain Au films on Ti with specific morphological and topographic properties for desired applications in which the Ti adhesion layer is needed for Au.

SEM Analysis of Surface Impact on Biofilm Antibiotic Treatment.

Science.gov (United States)

Gomes, Luciana Calheiros; Mergulhão, Filipe José

2017-01-01

The aim of this work was to use scanning electron microscopy (SEM) to investigate the effect of ampicillin treatment on Escherichia coli biofilms formed on two surface materials with different properties, silicone (SIL) and glass (GLA). Epifluorescence microscopy (EM) was initially used to assess biofilm formation and killing efficiency on both surfaces. This technique showed that higher bacterial colonization was obtained in the hydrophobic SIL than in the hydrophilic GLA. It has also shown that higher biofilm inactivation was attained for GLA after the antibiotic treatment (7-log reduction versus 1-log reduction for SIL). Due to its high resolution and magnification, SEM enabled a more detailed analysis of the antibiotic effect on biofilm cells, complementing the killing efficiency information obtained by EM. SEM micrographs revealed that ampicillin-treated cells have an elongated form when compared to untreated cells. Additionally, it has shown that different materials induced different levels of elongation on cells exposed to antibiotic. Biofilms formed on GLA showed a 37% higher elongation than those formed on SIL. Importantly, cell elongation was related to viability since ampicillin had a higher bactericidal effect on GLA-formed biofilms. These findings raise the possibility of using SEM for understanding the efficacy of antimicrobial treatments by observation of biofilm morphology.

Surface morphology of laser superheated Pb(111)

Energy Technology Data Exchange (ETDEWEB)

Zhang, Z. H.; Lin, Bo; Zeng, X. L.; Elsayed-Ali, H. E.

1998-05-01

The step density on the vicinal Pb(111) surface after laser superheating and melting is investigated using reflection high-energy electron diffraction. The (00) beam profiles parallel and perpendicular to the incident beam are analyzed. For laser heating with ˜100 ps laser pulses, surface superheating does not significantly change the density of the steps and step edge roughness. A sudden increase in the average terrace width is observed after laser surface melting. The average terrace width and the string length at the step edge become as large as those at room temperature. The average terrace width at 573 K changes from 38±15 to 64±19 Å after laser surface melting, while the average string length at the step edge changes from 50±12 to 250±38 Å.

Laser sintering of magnesia with nanoparticles of iron oxide and aluminum oxide

Energy Technology Data Exchange (ETDEWEB)

García, L.V.; Mendivil, M.I.; Roy, T.K. Das; Castillo, G.A. [Facultad de Ingenieria Mecanica y Electrica, Universidad Autonoma de Nuevo Leon, Av. Pedro de Alba s/n, Cd. Universitaria, San Nicolas de los Garza, Nuevo Leon 66451 (Mexico); Shaji, S., E-mail: sshajis@yahoo.com [Facultad de Ingenieria Mecanica y Electrica, Universidad Autonoma de Nuevo Leon, Av. Pedro de Alba s/n, Cd. Universitaria, San Nicolas de los Garza, Nuevo Leon 66451 (Mexico); CIIDIT, Universidad Autonoma de Nuevo Leon, Apodaca, Nuevo Leon (Mexico)

2015-05-01

Highlights: • Laser sintered MgO pellets with nanoparticles of Al{sub 2}O{sub 3} and Fe{sub 2}O{sub 3}. • Characterized these pellets by XRD, SEM and XPS. • Spinel formations were observed in both cases. • Changes in morphology and structure were analyzed. - Abstract: Nanoparticles of iron oxide (Fe{sub 2}O{sub 3}, 20–40 nm) and aluminum oxide (Al{sub 2}O{sub 3}, 50 nm) were mixed in different concentrations (3, 5 and 7 wt%) in a magnesium oxide (MgO) matrix. The mixture pellet was irradiated with 532 nm output from a Q-switched Nd:YAG laser using different laser fluence and translation speed for sintering. The refractory samples obtained were analyzed using X-ray diffraction technique, scanning electron microscopy and X-ray photoelectron spectroscopy. The results showed that the samples irradiated at translation speed of 110 μm/s and energy fluence of 1.7 J/cm{sup 2} with a concentration of 5 and 7 wt% of Fe{sub 2}O{sub 3} presented the MgFe{sub 2}O{sub 4} spinel-type phase. With the addition of Al{sub 2}O{sub 3} nanoparticles, at a translation speed of 110 μm/s and energy fluence of 1.7 J/cm{sup 2}, there were the formations of MgAl{sub 2}O{sub 4} spinel phase. The changes in morphologies and microstructure due to laser irradiation were analyzed.

Optimization of hybrid laser arc welding of 42CrMo steel to suppress pore formation

Energy Technology Data Exchange (ETDEWEB)

Zhang, Yan [Hunan University, State Key Laboratory of Advanced Design and Manufacturing for Vehicle Body, Changsha (China); Hunan Institute of Science and Technology, College of Mechanical Engineering, Yueyang (China); Chen, Genyu; Mao, Shuai; Zhou, Cong; Chen, Fei [Hunan University, State Key Laboratory of Advanced Design and Manufacturing for Vehicle Body, Changsha (China)

2017-06-15

The hybrid laser arc welding (HLAW) of 42CrMo quenched and tempered steel was conducted. The effect of the processing parameters, such as the relative positions of the laser and the arc, the shielding gas flow rate, the defocusing distance, the laser power, the wire feed rate and the welding speed, on the pore formation was analyzed, the morphological characteristics of the pores were analyzed using scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS). The results showed that the majority of the pores were invasive. The pores formed at the leading a laser (LA) welding process were fewer than those at the leading a arc (AL) welding process. Increasing the shielding gas flow rate could also facilitate the reduction of pores. The laser power and the welding speed were two key process parameters to reduce the pores. The flow of the molten pool, the weld cooling rate and the pore escaping rate as a result of different parameters could all affect pore formation. An ideal pore-free weld was obtained for the optimal welding process parameters. (orig.)

Evaluating the Use of Synthetic Replicas for SEM Identification of Bloodstains (with Emphasis on Archaeological and Ethnographic Artifacts).

Science.gov (United States)

Hortolà, Policarp

2015-12-01

Some archaeological or ethnographic specimens are unavailable for direct examination using a scanning electron microscope (SEM) due to methodological obstacles or legal issues. In order to assess the feasibility of using SEM synthetic replicas for the identification of bloodstains (BSs) via morphology of red blood cells (RBCs), three fragments of different natural raw material (inorganic, stone; plant, wood; animal, shell) were smeared with peripheral human blood. Afterwards, molds and casts of the bloodstained areas were made using vinyl polysiloxane (VPS) silicone impression and polyurethane (PU) resin casting material, respectively. Then, the original samples and the resulting casts were coated with gold and examined in secondary-electron mode using a high-vacuum SEM. Results suggest that PU resin casts obtained from VPS silicone molds can preserve RBC morphology in BSs, and consequently that synthetic replicas are feasible for SEM identification of BSs on cultural heritage specimens made of natural raw materials. Although the focus of this study was on BSs, the method reported in this paper may be applicable to organic residues other than blood, as well as to the surface of other specimens when, for any reason, the original is unavailable for an SEM.

In vitro study of 960 nm high power diode laser applications in dental enamel, aided by the presence of a photoinitiator dye: scanning electron microscopy analysis

International Nuclear Information System (INIS)

Oliveira, Marcelo Vinicius de

2002-06-01

The objective of this study is to verify if a high power diode laser can effectively modify the morphology of an enamel surface, and if this can be done in a controlled fashion by changing the lasers parameters. Previous studies using SEM demonstrated that through irradiation with Nd:YAG laser (1064 nm) it is possible to modify the morphology of the dental surface in such way as to increase its resistance against caries decays. The desired procedures that should achieve a decrease of the index of caries decays and of its sequels are on a primary level, which means that action is necessary before the disease installs itself. In this study it was used for the first time a prototype of a high power diode laser operating at 960 nm, produced by the Laboratory of Development of Lasers of the Center for Lasers and Applications of the IPEN. This equipment can present several advantages as reliability, reduced size and low cost. The aim was establish parameters of laser irradiation that produce the desired effects wanted in the enamel and protocols that guarantee its safety during application in dental hard tissues, protecting it of heating effects such as fissures and carbonization. (author)

Análise química e morfológica do esmalte dentário humano tratado com laser argônio durante a colagem ortodôntica Chemical and morphological analysis of the human dental enamel treated with argon laser during orthodontic bonding

Directory of Open Access Journals (Sweden)

Glaucio Serra Guimarães

2011-04-01

Full Text Available INTRODUÇÃO: as principais utilizações do laser argônio na Ortodontia são a redução do tempo de polimerização durante a colagem ortodôntica e o aumento da resistência à cárie do esmalte dentário. OBJETIVO: o objetivo deste trabalho foi avaliar as alterações químicas e morfológicas do esmalte dentário humano tratado com laser argônio nos parâmetros da colagem ortodôntica. MÉTODOS: quinze primeiros pré-molares hígidos, extraídos por indicação ortodôntica, foram selecionados e seccionados no sentido do longo eixo em dois segmentos iguais. Uma metade de cada elemento dentário foi tratada e a outra permaneceu sem tratamento. Um total de 30 amostras foi analisado, criando o grupo laser (n = 15 e o grupo controle (n = 15. O tratamento foi feito com laser argônio com 250mW de potência por 5 segundos, com densidade de energia de 8J/cm². RESULTADOS: a análise de difração de raios X demonstrou duas fases em ambos os grupos, as fases apatita e monetita. A redução da fase monetita foi significativa após o tratamento com laser, sugerindo maior cristalinidade. A análise de Espectroscopia de Energia Dispersiva (EDS indicou aumento na razão cálcio-fósforo no grupo laser, compatível com a diminuição da fase monetita. A morfologia superficial do esmalte dentário apresentou-se mais lisa após o tratamento com laser argônio. CONCLUSÕES: o aumento de cristalinidade e a lisura superficial do esmalte no grupo laser são fatores sugestivos de aumento de resistência à cárie no esmalte dentário.INTRODUCTION: The main utilities of the argon laser in orthodontics are the high speed curing process in orthodontic bonding and the caries resistance promotion of the tooth enamel. OBJECTIVE: The objective of this study was to evaluate the chemical and morphological changes in the tooth enamel treated with the argon laser in the orthodontic bonding parameters. METHODS: Fifteen sound human first premolars, removed for orthodontic

Comparison of SEM and VPSEM imaging techniques with respect to Streptococcus mutans biofilm topography.

Science.gov (United States)

Weber, Kathryn; Delben, Juliana; Bromage, Timothy G; Duarte, Simone

2014-01-01

The study compared images of mature Streptococcus mutans biofilms captured at increasing magnification to determine which microscopy method is most acceptable for imaging the biofilm topography and the extracellular polymeric substance (EPS). In vitro S. mutans biofilms were imaged using (1) scanning electron microscopy (SEM), which requires a dehydration process; (2) SEM and ruthenium red (SEM-RR), which has been shown to support the EPS of biofilms during the SEM dehydration; and (3) variable pressure scanning electron microscopy (VPSEM), which does not require the intensive dehydration process of SEM. The dehydration process and high chamber vacuum of both SEM techniques devastated the biofilm EPS, removed supporting structures, and caused cracking on the biofilm surface. The VPSEM offered the most comprehensive representation of the S. mutans biofilm morphology. VPSEM provides similar contrast and focus as the SEM, but the procedure is far less time-consuming, and the use of hazardous chemicals associated with SEM dehydration protocol is avoided with the VPSEM. The inaccurate representations of the biofilm EPS in SEM experimentation is a possible source of inaccurate data and impediments in the study of S. mutans biofilms. © 2013 Federation of European Microbiological Societies. Published by John Wiley & Sons Ltd. All rights reserved.

Surface ultrastructural (SEM) characteristics of oropharyngeal cavity of house sparrow (Passer domesticus).

Science.gov (United States)

Abumandour, Mohamed M A

2018-06-01

The focus of the present study is to provide a full morphological description of the oropharyngeal cavity of the house sparrow. The head of six birds was prepared for gross examination and by stereo and electron microscopy. The bifid lingual apex has multiple long, rostrally directed needle-like processes. The lateral border of the apex carries rostromedially directed needle-like processes. The dorsal lingual surface of the apex and body carries numerous caudomedially directed filiform papillae and many orifices of lingual salivary glands. The lingual body is divided into two parts: rostral and caudal. The caudal part is divided into two laterally elevated regions by a median groove, while the rostral part is bounded laterally by a rostrodorsally directed papillary row, which on SEM is formed from two rows. On SEM, the lingual root has many orifices of posterior salivary glands. The pharyngeal papillary row is located at the caudal border of the laryngeal mound, but this single papillary row is formed from two rows at SEM magnification. The laryngeal cleft continues caudally as a laryngeal fissure bounded by two longitudinal rows of caudally directed papillae; at high SEM magnification, this fissure is divided into two halves by a median ridge which carries caudally directed papillae on its posterior part. The choanal cleft proceeds rostrally by the median tubercle. There are a small number of orifices of palatine salivary glands. The morphological characters of the oropharyngeal cavity of the sparrow confirm its adaptation to surrounding environmental conditions and available food particles.

Characterisation of rust surfaces formed on mild steel exposed to marine atmospheres using XRD and SEM/Micro-Raman techniques

International Nuclear Information System (INIS)

Fuente, D. de la; Alcántara, J.; Chico, B.; Díaz, I.; Jiménez, J.A.; Morcillo, M.

2016-01-01

Highlights: • SEM/Micro-Raman is very useful for characterizing rust phases morphologies. • SEM/Micro-Raman enables unequivocal rust phases identification. • γ-FeOOH basically presents two types of morphologies: globular and laminar. • Fe 3 O 4 presents two morphologies: flat patches and black doughnut-type formations. • β-FeOOH presents highly porous morphologies comprised by fine prismatic crystals. - Abstract: The exposure of mild steel to marine atmospheres gives rise to the formation of various corrosion products, mainly lepidocrocite, goethite, magnetite and akaganeite. In this study, Grazing Incidence X-Ray Diffraction, Micro-X-Ray Diffraction and Scanning Electron Microscopy/Micro-Raman are used to characterise rust layer surfaces and to identify the principal component rust phases and their morphology. The main conclusion reached is that lepidocrocite is preferentially located on the outermost surface while magnetite and akaganeite form mostly close to base steel. The Scanning Electron Microscopy/Micro-Raman technique has been very useful for characterising (identifying) the wide variety of morphologies presented by the rust phases.

Tillandsia stricta Sol (Bromeliaceae) leaves as monitors of airborne particulate matter-A comparative SEM methods evaluation: Unveiling an accurate and odd HP-SEM method.

Science.gov (United States)

de Oliveira, Martha Lima; de Melo, Edésio José Tenório; Miguens, Flávio Costa

2016-09-01

Airborne particulate matter (PM) has been included among the most important air pollutants by governmental environment agencies and academy researchers. The use of terrestrial plants for monitoring PM has been widely accepted, particularly when it is coupled with SEM/EDS. Herein, Tillandsia stricta leaves were used as monitors of PM, focusing on a comparative evaluation of Environmental SEM (ESEM) and High-Pressure SEM (HPSEM). In addition, specimens air-dried at formaldehyde atmosphere (AD/FA) were introduced as an SEM procedure. Hydrated specimen observation by ESEM was the best way to get information from T. stricta leaves. If any artifacts were introduced by AD/FA, they were indiscernible from those caused by CPD. Leaf anatomy was always well preserved. PM density was determined on adaxial and abaxial leaf epidermis for each of the SEM proceedings. When compared with ESEM, particle extraction varied from 0 to 20% in air-dried leaves while 23-78% of particles deposited on leaves surfaces were extracted by CPD procedures. ESEM was obviously the best choice over other methods but morphological artifacts increased in function of operation time while HPSEM operation time was without limit. AD/FA avoided the shrinkage observed in the air-dried leaves and particle extraction was low when compared with CPD. Structural and particle density results suggest AD/FA as an important methodological approach to air pollution biomonitoring that can be widely used in all electron microscopy labs. Otherwise, previous PM assessments using terrestrial plants as biomonitors and performed by conventional SEM could have underestimated airborne particulate matter concentration. © 2016 Wiley Periodicals, Inc.

Super-resolution for asymmetric resolution of FIB-SEM 3D imaging using AI with deep learning.

Science.gov (United States)

Hagita, Katsumi; Higuchi, Takeshi; Jinnai, Hiroshi

2018-04-12

Scanning electron microscopy equipped with a focused ion beam (FIB-SEM) is a promising three-dimensional (3D) imaging technique for nano- and meso-scale morphologies. In FIB-SEM, the specimen surface is stripped by an ion beam and imaged by an SEM installed orthogonally to the FIB. The lateral resolution is governed by the SEM, while the depth resolution, i.e., the FIB milling direction, is determined by the thickness of the stripped thin layer. In most cases, the lateral resolution is superior to the depth resolution; hence, asymmetric resolution is generated in the 3D image. Here, we propose a new approach based on an image-processing or deep-learning-based method for super-resolution of 3D images with such asymmetric resolution, so as to restore the depth resolution to achieve symmetric resolution. The deep-learning-based method learns from high-resolution sub-images obtained via SEM and recovers low-resolution sub-images parallel to the FIB milling direction. The 3D morphologies of polymeric nano-composites are used as test images, which are subjected to the deep-learning-based method as well as conventional methods. We find that the former yields superior restoration, particularly as the asymmetric resolution is increased. Our super-resolution approach for images having asymmetric resolution enables observation time reduction.

Morphology selection for cupric oxide thin films by electrodeposition.

Science.gov (United States)

Dhanasekaran, V; Mahalingam, T; Chandramohan, R

2011-10-01

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

Morphology and orientation of β-BaB{sub 2}O{sub 4} crystals patterned by laser in the inside of samarium barium borate glass

Energy Technology Data Exchange (ETDEWEB)

Nishii, Akihito; Shinozaki, Kenji; Honma, Tsuyoshi; Komatsu, Takayuki, E-mail: komatsu@mst.nagaokaut.ac.jp

2015-01-15

Nonlinear optical β-BaB{sub 2}O{sub 4} crystal lines (β-BBO) were patterned in the inside of 8Sm{sub 2}O{sub 3}–42BaO–50B{sub 2}O{sub 3} glass by irradiations of continuous-wave Yb:YVO{sub 4} lasers with a wavelength of 1080 nm (power: P=0.8–1.0 W, scanning speed: S=0.2–2.5 μm/s), in which the laser focal position was moved gradually from the surface to the inside. The morphology, size, and orientation of β-BBO crystals were examined from polarization optical microscope and birefringence imaging observations. It was demonstrated that c-axis oriented β-BBO crystals with long lengths (e.g., 20 mm) were patterned in the inside of the glass. The morphology of β-BBO in the cross-section of lines was a rectangular shape with rounded corners, and the volume of β-BBO formed increased with increasing laser power and with decreasing laser scanning speed. The maximum depth in the inside from the surface for β-BBO patterning increased with increasing laser power, e.g., D{sub max}∼100 μm at P=0.8 W, D{sub max}∼170 μm at P=0.9 W, and D{sub max}∼200 μm at P=1 W. The present study proposes that the laser-induced crystallization opens a new door for applied engineering in glassy solids. - Graphical abstract: This figure shows the POM photographs for β-BaB{sub 2}O{sub 4} crystal lines patterned by cw Yb:YVO{sub 4} fiber laser irradiations with a laser power of P=0.8 W and a laser scanning speed S=2 μm/s in the glass. The laser focal point was moved gradually from the surface into the inside. The results shown in Fig. 1 demonstrate that it is possible to pattern highly oriented β-BaB{sub 2}O{sub 4} crystals even in the inside of glasses. - Highlights: • β-BaB{sub 2}O{sub 4} crystal lines were patterned in the inside of a glass by lasers. • Laser focal position was moved gradually from the surface to the inside. • Birefringence imaging was observed. • Morphology, size, and orientation of crystals were clarified. • Crystal lines with long lengths

Morphology and structural studies of WO_3 films deposited on SrTiO_3 by pulsed laser deposition

International Nuclear Information System (INIS)

Kalhori, Hossein; Porter, Stephen B.; Esmaeily, Amir Sajjad; Coey, Michael; Ranjbar, Mehdi; Salamati, Hadi

2016-01-01

Highlights: • Highly oriented WO_3 stoichiometric films were determined using pulsed laser deposition method. • Effective parameters on thin films including temperature, oxygen partial pressure and laser energy fluency was studied. • A phase transition was observed in WO_3 films at 700 °C from monoclinic to tetragonal. - Abstract: WO_3 films have been grown by pulsed laser deposition on SrTiO_3 (001) substrates. The effects of substrate temperature, oxygen partial pressure and energy fluence of the laser beam on the physical properties of the films were studied. Reflection high-energy electron diffraction (RHEED) patterns during and after growth were used to determine the surface structure and morphology. The chemical composition and crystalline phases were obtained by XPS and XRD respectively. AFM results showed that the roughness and skewness of the films depend on the substrate temperature during deposition. Optimal conditions were determined for the growth of the highly oriented films.

The Effects of Sn Addition on the Microstructure and Surface Properties of Laser Deposited Al-Si-Sn Coatings on ASTM A29 Steel

Science.gov (United States)

Fatoba, Olawale S.; Akinlabi, Stephen A.; Akinlabi, Esther T.

2018-03-01

Aluminium and its alloys have been successful metal materials used for many applications like commodity roles, automotive and vital structural components in aircrafts. A substantial portion of Al-Fe-Si alloy is also used for manufacturing the packaging foils and sheets for common heat exchanger applications. The present research was aimed at studying the morphology and surface analyses of laser deposited Al-Sn-Si coatings on ASTM A29 steel. These Fe-intermetallic compounds influence the material properties during rapid cooling by laser alloying technique and play a crucial role for the material quality. Thus, it is of considerable technological interest to control the morphology and distribution of these phases in order to eliminate the negative effects on microstructure. A 3 kW continuous wave ytterbium laser system (YLS) attached to a KUKA robot which controls the movement of the alloying process was utilized for the fabrication of the coatings at optimum laser parameters. The fabricated coatings were investigated for its hardness and wear resistance performance. The field emission scanning electron microscope equipped with energy dispersive spectroscopy (SEM/EDS) was used to study the morphology of the fabricated coatings and X-ray diffractometer (XRD) for the identification of the phases present in the coatings. The coatings were free of cracks and pores with homogeneous and refined microstructures. The enhanced hardness and wear resistance performance were attributed to metastable intermetallic compounds formed.

3D-imaging of selective laser melting defects in a Co–Cr–Mo alloy by synchrotron radiation micro-CT

International Nuclear Information System (INIS)

Zhou, Xin; Wang, Dianzheng; Liu, Xihe; Zhang, DanDan; Qu, Shilian; Ma, Jing; London, Gary; Shen, Zhijian; Liu, Wei

2015-01-01

Microstructure defects set the mechanical property limits for solid Co–Cr–Mo alloy prepared by selective laser melting (SLM). Previous studies were mainly based on 2D SEM images and thus not able to provide information of the 3D morphologies of the complex defects. In this paper, the remaining porosities in Co–Cr–Mo alloy parts prepared by selective laser melting were presented in relation to the laser processing parameters. In order to understand the defect forming mechanism, accurate 3D images of defects inside SLM fabricated Co–Cr–Mo samples were provided by synchrotron radiation micro-CT imaging of 300 μm thick slices cut from a 10 mm cube. With 3D reconstructed images distinctive morphologies of SLM defects spanning across the consolidated powder layers were generated. The faults can be classified as single layer or multi-layers defects. The accidental single layer defects form as gaps between adjacent laser melt tracks or melt track discontinuousness caused by inherent fluid instability under various disturbances. The first formed single layer defect generates often a multi-layer defect spanning for 2–3 subsequent powder layers. By stabilizing the melt pool flow and by reducing the surface roughness through adjusting processing parameters it appears possible to reduce the defect concentrations

Ultrastructural analysis of root canal dentine irradiated with 980-nm diode laser energy at different parameters.

Science.gov (United States)

Marchesan, Melissa Andréia; Brugnera-Junior, Aldo; Souza-Gabriel, Aline Evangelista; Correa-Silva, Silvio Rocha; Sousa-Neto, Manoel D

2008-06-01

The purpose of this in vitro study was to investigate using the scanning electron microscope (SEM) the ultrastructural morphological changes of the radicular dentine surface after irradiation with 980-nm diode laser energy at different parameters and angles of incidence. There have been limited reports on the effects of diode laser irradiation at 980 nm on radicular dentin morphology. Seventy-two maxillary canines were sectioned and roots were biomechanically prepared using K3 rotary instruments. The teeth were irrigated with 2 mL of distilled water between files and final irrigation was performed with 10 mL of distilled water. The teeth were then randomly divided into five groups (n = 8 each) according to their diode laser parameters: Group 1: no irradiation (control); group 2: 1.5 W/continuous wave (CW) emission (the manufacturer's parameters); group 3: 1.5 W/100 Hz; group 4: 3 W/CW; and group 5: 3 W/100 Hz. Laser energy was applied with helicoid movements (parallel to the canal walls) for 20 sec. Eight additional teeth for each group were endodontically prepared and split longitudinally and irradiation was applied perpendicularly to the root surface. Statistical analysis showed no difference between the root canal thirds irradiated with the 980-nm diode laser, and similar results between the parameters 1.5 W/CW and 3 W/100 Hz (p > 0.05). When considering different output powers and delivery modes our results showed that changes varied from smear layer removal to dentine fusion.

Dynamics of Gradient Bioceramic Composite Coating on Surface of Titanium Alloy by Wide-Band Laser Cladding

Institute of Scientific and Technical Information of China (English)

LIU Qi-bin; ZOU Long-jiang; ZHU Wei-dong; LI Hai-tao; DONG Chuang

2004-01-01

The gradient bioceramic coating was prepared on the surface of titanium alloy using wide-band laser cladding. The dynamics of gradient bioceramic composite coating containing hydroxyapatite (HA) prepared with mixture of CaHPO4*2H2O and CaCO3 under the condition of wide-band laser was studied theoretically. The corresponding mathematical model and its numerical solution were presented. The examination experiment showed that HA bioceramic composite coatings can be obtained by appropriately choosing wide-band laser cladding parameters. The microstructure and surface morphology of HA bioceramic coating were observed by SEM and X-ray diffraction. The experimental results showed that the bioceramic coating is composed of HA, β-TCP, CaO, CaTiO3 and TiO2. The surface of bioceramic coating takes coral-shaped structure or short-rod piled structure, which helps osteoblast grow into bioceramic and improves the biocompatibility.

Fabrication of hydrophobic structures on coronary stent surface based on direct three-beam laser interference lithography

Science.gov (United States)

Gao, Long-yue; Zhou, Wei-qi; Wang, Yuan-bo; Wang, Si-qi; Bai, Chong; Li, Shi-ming; Liu, Bin; Wang, Jun-nan; Cui, Cheng-kun; Li, Yong-liang

2016-05-01

To solve the problems with coronary stent implantation, coronary artery stent surface was directly modified by three-beam laser interference lithography through imitating the water-repellent surface of lotus leaf, and uniform micro-nano structures with the controllable period were fabricated. The morphological properties and contact angle (CA) of the microstructure were measured by scanning electron microscope (SEM) and CA system. The water repellency of stent was also evaluated by the contact and then separation between the water drop and the stent. The results show that the close-packed concave structure with the period of about 12 μm can be fabricated on the stent surface with special parameters (incident angle of 3°, laser energy density of 2.2 J·cm-2 and exposure time of 80 s) by using the three-beam laser at 1 064 nm, and the structure has good water repellency with CA of 120°.

Surface morphology of laser superheated Pb(100)

Energy Technology Data Exchange (ETDEWEB)

Zhang, Z.H.; Lin, B.; Elsayed-Ali, H.E.

1999-11-01

The change in the surface vacancy density after heating of Pb(100) with {approximately}100 ps laser pulses is investigated using reflection high-energy electron diffraction. The surface vacancy density remains unchanged when the surface is superheated without melting. However, when the laser fluence is high enough to cause surface melting, the surface vacancy density increases. This increase in vacancy density is attributed to fast diffusion of atoms in the liquid film formed on Pb(100) during laser melting.

Nd:YOV4 laser polishing on WC-Co HVOF coating

Science.gov (United States)

Giorleo, L.; Ceretti, E.; Montesano, L.; La Vecchia, G. M.

2017-10-01

WC/Co coatings are widely applied to different types of components due to their extraordinary performance properties including high hardness and wear properties. In industrial applications High Velocity Oxy-Fuel (HVOF) technique is extensively used to deposit hard metal coatings. The main advantage of HVOF compared to other thermal spray techniques is the ability to accelerate the melted powder particles of the feedstock material at a relatively high velocity, leading to obtain good adhesion and low porosity level. However, despite the mentioned benefits, the surface finish quality of WC-Co HVOF coatings results to be poor (Ra higher than 5 µm) thus a mechanical polishing process is often needed. The main problem is that the high hardness of coating leads the polishing process expensive in terms of time and tool wear; moreover polishing becomes difficult and not always possible in case of limited accessibility of a part, micro dimensions or undercuts. Nowadays a different technique available to improve surface roughness is the laser polishing process. The polishing principle is based on focused radiation of a laser beam that melts a microscopic layer of surface material. Compared to conventional polishing process (as grinding) it ensures the possibility of avoiding tool wear, less pollution (no abrasive or liquids), no debris, less machining time and coupled with a galvo system it results to be more suitable in case of 3D complex workpieces. In this paper laser polishing process executed with a Nd:YOV4 Laser was investigated: the effect of different process parameters as initial coating morphology, laser scan speed and loop cycles were tested. Results were compared by a statistical approach in terms of average roughness along with a morphological analysis carried out by Scanning Electron Microscope (SEM) investigation coupled with EDS spectra.

Fiber laser cladding of nickel-based alloy on cast iron

Energy Technology Data Exchange (ETDEWEB)

Arias-González, F., E-mail: felipeag@uvigo.es [Applied Physics Dpt., University of Vigo, EEI, Lagoas-Marcosende, Vigo E-36310 (Spain); Val, J. del [Applied Physics Dpt., University of Vigo, EEI, Lagoas-Marcosende, Vigo E-36310 (Spain); Comesaña, R. [Materials Engineering, Applied Mechanics and Construction Dpt., University of Vigo, EEI, Lagoas-Marcosende, Vigo E-36310 (Spain); Penide, J.; Lusquiños, F.; Quintero, F.; Riveiro, A.; Boutinguiza, M.; Pou, J. [Applied Physics Dpt., University of Vigo, EEI, Lagoas-Marcosende, Vigo E-36310 (Spain)

2016-06-30

Highlights: • Fiber laser cladding of Ni-based alloy on cast iron was experimentally studied. • Two different types of cast iron have been analyzed: gray and ductile cast iron. • Suitable processing parameters to generate a Ni-based coating were determined. • Dilution is higher in gray cast iron samples than in ductile cast iron. • Ni-based coating presents higher hardness than cast iron but similar Young's modulus. - Abstract: Gray cast iron is a ferrous alloy characterized by a carbon-rich phase in form of lamellar graphite in an iron matrix while ductile cast iron presents a carbon-rich phase in form of spheroidal graphite. Graphite presents a higher laser beam absorption than iron matrix and its morphology has also a strong influence on thermal conductivity of the material. The laser cladding process of cast iron is complicated by its heterogeneous microstructure which generates non-homogeneous thermal fields. In this research work, a comparison between different types of cast iron substrates (with different graphite morphology) has been carried out to analyze its impact on the process results. A fiber laser was used to generate a NiCrBSi coating over flat substrates of gray cast iron (EN-GJL-250) and nodular cast iron (EN-GJS-400-15). The relationship between processing parameters (laser irradiance and scanning speed) and geometry of a single laser track was examined. Moreover, microstructure and composition were studied by Scanning Electron Microscopy (SEM), Energy Dispersive X-Ray Spectroscopy (EDS) and X-Ray Diffraction (XRD). The hardness and elastic modulus were analyzed by means of micro- and nanoindentation. A hardfacing coating was generated by fiber laser cladding. Suitable processing parameters to generate the Ni-based alloy coating were determined. For the same processing parameters, gray cast iron samples present higher dilution than cast iron samples. The elastic modulus is similar for the coating and the substrate, while the Ni

3D reconstruction and characterization of carbides in Ni-based high carbon alloy in a FIB-SEM system

Energy Technology Data Exchange (ETDEWEB)

Bala, Piotr [AGH Univ. of Science and Technology, Faculty of Metals Engineering and Industrial Computer Science, Krakow (Poland); AGH Univ. of Science and Technology, Academic Centre of Materials and Nanotechnology, Krakow (Poland); Tsyrulin, Katja; Jaksch, Heiner [Carl-Zeiss, Oberkochen (Germany); Stepien, Milena [AGH Univ. of Science and Technology, Academic Centre of Materials and Nanotechnology, Krakow (Poland)

2015-07-15

Dual beam focused ion beam scanning electron microscopes (FIB-SEMs) are well suited for characterizing micron and submicron size microstructural features in three dimensions throughout a serial-sectioning experiment. In this article, a FIB-SEM instrument was used to collect morphological, crystallographic, and chemical information for an Ni-Ta-Al-Cr alloy of high carbon content. The alloy has been designed to have excellent tribological properties at elevated temperatures. The morphology, spatial distribution, scale, and degree of interconnection of primary carbides in the Ni-Ta-Al-Cr-C alloy was assessed via serial sectioning in a casting cross-section. The 3D reconstructions showed that the primary carbides and dendrites were forming a dendrite surrounded by primary carbide network over the entire cross-section. Additionally, the morphology and spatial distribution of secondary carbides after heat treatment was determined.

Monolayer to MTS: using SEM, HIM, TEM and SERS to compare morphology, nanosensor uptake and redox potential in MCF7 cells

Science.gov (United States)

Jamieson, L. E.; Bell, A. P.; Harrison, D. J.; Campbell, C. J.

2015-06-01

Cellular redox potential is important for the control and regulation of a vast number of processes occurring in cells. When the fine redox potential balance within cells is disturbed it can have serious consequences such as the initiation or progression of disease. It is thought that a redox gradient develops in cancer tumours where the peripheral regions are well oxygenated and internal regions, further from vascular blood supply, become starved of oxygen and hypoxic. This makes treatment of these areas more challenging as, for example, radiotherapy relies on the presence of oxygen. Currently techniques for quantitative analysis of redox gradients are limited. Surface enhanced Raman scattering (SERS) nanosensors (NS) have been used to detect redox potential in a quantitative manner in monolayer cultured cells with many advantages over other techniques. This technique has considerable potential for use in multicellular tumour spheroids (MTS) - a three dimensional (3D) cell model which better mimics the tumour environment and gradients that develop. MTS are a more realistic model of the in vivo cellular morphology and environment and are becoming an increasingly popular in vitro model, replacing traditional monolayer culture. Imaging techniques such as transmission electron microscopy (TEM), scanning electron microscopy (SEM) and helium ion microscopy (HIM) were used to investigate differences in morphology and NS uptake in monolayer culture compared to MTS. After confirming NS uptake, the first SERS measurements revealing quantitative information on redox potential in MTS were performed.

Morphology and Curie temperature engineering in crystalline La{sub 0.7}Sr{sub 0.3}MnO{sub 3} films on Si by pulsed laser deposition

Energy Technology Data Exchange (ETDEWEB)

Nori, Rajashree, E-mail: rajsre@ee.iitb.ac.in; Ganguly, U.; Ravi Chandra Raju, N.; Pinto, R.; Ramgopal Rao, V. [Centre of Excellence in Nanoelectronics, Department of Electrical Engineering, Indian Institute of Technology-Bombay (IIT-B), Mumbai 400076 (India); Kale, S. N. [Department of Applied Physics, Defence Institute of Advanced Technology (DIAT), Pune 411025 (India); Sutar, D. S. [Central Surface Analytical Facility, Indian Institute of Technology-Bombay (IIT-B), Mumbai 400076 (India)

2014-01-21

Of all the colossal magnetoresistant manganites, La{sub 0.7}Sr{sub 0.3}MnO{sub 3} (LSMO) exhibits magnetic and electronic state transitions above room temperature, and therefore holds immense technological potential in spintronic devices and hybrid heterojunctions. As the first step towards this goal, it needs to be integrated with silicon via a well-defined process that provides morphology and phase control, along with reproducibility. This work demonstrates the development of pulsed laser deposition (PLD) process parameter regimes for dense and columnar morphology LSMO films directly on Si. These regimes are postulated on the foundations of a pressure-distance scaling law and their limits are defined post experimental validation. The laser spot size is seen to play an important role in tandem with the pressure-distance scaling law to provide morphology control during LSMO deposition on lattice-mismatched Si substrate. Additionally, phase stability of the deposited films in these regimes is evaluated through magnetometry measurements and the Curie temperatures obtained are 349 K (for dense morphology) and 355 K (for columnar morphology)—the highest reported for LSMO films on Si so far. X-ray diffraction studies on phase evolution with variation in laser energy density and substrate temperature reveals the emergence of texture. Quantitative limits for all the key PLD process parameters are demonstrated in order enable morphological and structural engineering of LSMO films deposited directly on Si. These results are expected to boost the realization of top-down and bottom-up LSMO device architectures on the Si platform for a variety of applications.

High Temperature Dry Sliding Friction and Wear Performance of Laser Cladding WC/Ni Composite Coating

Directory of Open Access Journals (Sweden)

YANG Jiao-xi

2016-06-01

Full Text Available Two different types of agglomerate and angular WC/Ni matrix composite coatings were deposited by laser cladding. The high temperature wear resistance of these composite coatings was tested with a ring-on-disc MMG-10 apparatus. The morphologies of the worn surfaces were observed using a scanning electron microscopy (SEM equipped with an energy dispersive spectroscopy (EDS for elemental composition. The results show that the high temperature wear resistance of the laser clad WC/Ni-based composite coatings is improved significantly with WC mass fraction increasing. The 60% agglomerate WC/Ni composite coating has optimal high temperature wear resistance. High temperature wear mechanism of 60% WC/Ni composite coating is from abrasive wear of low temperature into composite function of the oxidation wear and abrasive wear.

Actual laser removal of black soiling crust from siliceous sandstone by high pulse repetition rate equipment: effects on surface morphology

Directory of Open Access Journals (Sweden)

Iglesias-Campos, M. A.

2016-03-01

Full Text Available This research project studies the role of pulse repetition rate in laser removal of black soiling crust from siliceous sandstone, and specifically, how laser fluence correlates with high pulse repetition rates in cleaning practice. The aim is to define practical cleaning processes and determine simple techniques for evaluation based on end-users’ perspective (restorers. Spot and surface tests were made using a Q-switched Nd:YAG laser system with a wide range of pulse repetition rates (5–200 Hz, systematically analysed and compared by macrophotography, portable microscope, stereomicroscope with 3D visualizing and area roughness measurements, SEM imaging and spectrophotometry. The results allow the conclusion that for operation under high pulse repetition rates the average of total energy applied per spot on a treated surface should be attendant upon fluence values in order to provide a systematic and accurate description of an actual laser cleaning intervention.En este trabajo se estudia el papel de la frecuencia de repetición en la limpieza láser de costras de contaminación sobre una arenisca silícea, y concretamente, como se relaciona fluencia y frecuencias elevadas en una limpieza real. Se pretende definir un procedimiento práctico de limpieza y determinar técnicas sencillas de evaluación desde el punto de vista de los usuarios finales (restauradores. Para el estudio se realizaron diferentes ensayos en spot y en superficie mediante un equipo Q-switched Nd:YAG con un amplio rango de frecuencias (5–200 Hz, que se analizaron y compararon sistemáticamente mediante macrofotografía, microscopio portátil, estereomicroscopio con visualización 3D y mediciones de rugosidad en área, imágenes SEM y espectrofotometría. Los resultados permiten proponer que, al trabajar con altas frecuencias, la media de la energía total depositada por spot en la superficie debería acompañar los valores de fluencia para describir y comprender mejor una

Characterisation of nanoparticles by means of high-resolution SEM/EDS in transmission mode

International Nuclear Information System (INIS)

Hodoroaba, V-D; Rades, S; Mielke, J; Ortel, E; Salge, T; Schmidt, R

2016-01-01

Advances in scanning electron microscopy (SEM) enable the high-resolution imaging of single nanoparticles (NPs) with sizes well below 10 nm. The SEM analysis in transmission mode (T-SEM) of NPs on thin film supports has many benefits when compared to the analysis of NPs on bulk substrates. The enhanced material (mass - thickness) contrast of the T-SEM imaging mode is well suited for in-depth and, particularly valuable, to very accurate, traceable, lateral dimensional measurements of NPs. Compared to samples prepared on bulk substrates, T-SEM with energy dispersive X-ray spectroscopy (EDS) achieves a drastically improved spatial resolution of the emitted X-rays. The poor signal-to-noise ratio of the X-ray spectra emitted by a single nanoparticle (NP) can be improved by the use of high-sensitivity (high collection solid angle) silicon drift (SDD), energy-dispersive X-ray spectrometers (EDS). The EDS spectral imaging of a single NP with a spatial resolution below 10 nm has become possible. This is demonstrated by means of various examples of nanostructures. Advanced data processing of T-SEM/EDS results sets the stage for the automated classification of NPs by feature analysis. This method combines the detection of morphological structures of interest by image processing of T-SEM micrographs with the chemical classification by EDS. (paper)

SEM examination and analysis of the interface character in surface modified aramid-epoxy composite

International Nuclear Information System (INIS)

Hussain, S.; Khan, M.B.; Hussain, R.

2011-01-01

The surface of Kevlar fibers is chemically modified by treatment with Phthalic anhydride (PA) and the effect is examined by SEM for the laser cut, three point bending and interlaminar shear delaminated surfaces. The surface modification improved the adhesion to epoxy resin that clearly leads to cohesive fracture as opposed to interfacial failure in the untreated specimen. SEM reveals marginal surface roughening of fibers without compromising their strength. The interface modification technique described in this paper is attractive thermodynamically as it does not compromise surface free energy of the polymer matrix or that of the fiber itself to enhance wet ability. (author)

New insights on laser-induced graphene electrodes for flexible supercapacitors: tunable morphology and physical properties.

Science.gov (United States)

Lamberti, Andrea; Perrucci, Francesco; Caprioli, Matteo; Serrapede, Mara; Fontana, Marco; Bianco, Stefano; Ferrero, Sergio; Tresso, Elena

2017-04-28

In certain polymers the graphenization of carbon atoms can be obtained by laser writing owing to the easy absorption of long-wavelength radiation, which generates photo-thermal effects. On a polyimide surface this process allows the formation of a nanostructured and porous carbon network known as laser-induced graphene (LIG). Herein we report on the effect of the process parameters on the morphology and physical properties of LIG nanostructures. We show that the scan speed and the frequency of the incident radiation affect the gas evolution, inducing different structure rearrangements, an interesting nitrogen self-doping phenomenon and consequently different conduction properties. The materials were characterized by infrared and Raman spectroscopy, XPS elemental analysis, electron microscopy and electrical/electrochemical measurements. In particular the samples were tested as interdigitated electrodes into electrochemical supercapacitors and the optimized LIG arrangement was tested in parallel and series supercapacitor configurations to allow power exploitation.

Sol-gel deposition and electrical properties of laser irradiated Cu doped TiO2 multilayer thin films

Directory of Open Access Journals (Sweden)

M.I. Khan

Full Text Available Multilayer thin films (3, 5 and 7 of 20% copper doped titanium dioxide (Cu:TiO2 have been deposited on glass substrates by sol-gel spin coating method. After deposition, films have been irradiated by a beam of continuous wave diode laser (532 nm for two minutes at the angle of 45°. Structural, surface morphology and electrical properties of films have been investigated by X-rays diffraction (XRD, scanning electron microscope (SEM and four point probe technique respectively. XRD shows the formation of titanium copper oxide. Surface morphology of thin films indicated that the average grain size is increased by increasing the number of layers. The average sheet resistivity of 3, 5 and 7 layers of thin films measured by four point probe technique is 2.2 × 104, 1.2 × 104 and 1.0 × 104 (Ohm-cm respectively. The present study will facilitate a cost effective and environmental friendly study for several properties of materials. Keywords: Cu:TiO2, Multilayer thin films, Diode laser

Monitoring of the morphologic reconstruction of deposited ablation products in laser irradiation of silicon

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Vlasova M.

2008-01-01

Full Text Available Using electron microscopy, atomic force microscopy, X-ray microanalysis, and IR spectroscopy, it was established that, in the regime of continuous laser irradiation of silicon at P = 170 W in different gaseous atmospheres with an oxygen impurity, SiOx composite films with a complex morphology form. The main components of ablation products are clusters that form during flight of ablation products and as a result of separation of SiOx-clusters from the zone of the irradiation channel. The roughness and density of the films depend on the heating temperature of the target surface and the type of deposited clusters.

Influence of repetitive pulsed laser irradiation on the surface characteristics of an aluminum alloy in the melting regime

International Nuclear Information System (INIS)

Choi, Sung Ho; Jhang, Kyung Young

2015-01-01

We have investigated the influence of repetitive near-infrared (NIR) pulsed laser shots in the melting regime on the surface characteristics of an aluminum 6061-T6 alloy. Characteristics of interest include surface morphology, surface roughness, and surface hardness in the melted zone as well as the size of the melted zone. For this study, the proper pulse energy for inducing surface melting at one shot is selected using numerical simulations that calculate the variation in temperature at the laser beam spot for various input pulse energies in order to find the proper pulse energy for raising the temperature to the melting point. In this study, 130 mJ was selected as the input energy for a Nd:YAG laser pulse with a duration of 5 ns. The size of the melted zone measured using optical microscopy (OM) increased logarithmically with an increasing shot number. The surface morphology observed by scanning electron microscopy (SEM) clearly showed a re-solidified microstructure evolution after surface melting. The surface roughness and hardness were measured by atomic force microscopy (AFM) and nano-indentation, respectively. The surface roughness showed almost no variation due to the surface texturing after laser shots over 10. The hardness inside the melted zone was lower than that outside the zone because the β'' phase was transformed to a β phase or dissolved into a matrix.

SEM Anthology

Science.gov (United States)

Rodgers, Michelle; Zimar, Heather

2004-01-01

The "SEM Anthology" is a compilation of articles by more than 30 enrollment management professionals from a variety of institutions across the country. This collection, which has appeared in SEM Monthly over the past year, chronicles Strategic Enrollment Management efforts at campuses nationwide. The book illustrates the successes and challenges…

Effects of Root Debridement With Hand Curettes and Er:YAG Laser on Chemical Properties and Ultrastructure of Periodontally-Diseased Root Surfaces Using Spectroscopy and Scanning Electron Microscopy

Science.gov (United States)

Amid, Reza; Gholami, Gholam Ali; Mojahedi, Masoud; Aghalou, Maryam; Gholami, Mohsen; Mirakhori, Mahdieh

2017-01-01

Introduction: The efficacy of erbium-doped yttrium aluminum garnet (Er:YAG) laser for root debridement in comparison with curettes has been the subject of many recent investigations. Considering the possibility of chemical and ultra-structural changes in root surfaces following laser irradiation, this study sought to assess the effects of scaling and root planing (SRP) with curettes and Er:YAG laser on chemical properties and ultrastructure of root surfaces using spectroscopy and scanning electron microscopy (SEM). Methods: In this in vitro experimental study, extracted sound human single-rooted teeth (n = 50) were randomly scaled using manual curettes alone or in conjunction with Er:YAG laser at 100 and 150 mJ/pulse output energies. The weight percentages of carbon, oxygen, phosphorous and calcium remaining on the root surfaces were calculated using spectroscopy and the surface morphology of specimens was assessed under SEM. Data were analyzed using one-way analysis of variance (ANOVA). Results: No significant differences (P > 0.05) were noted in the mean carbon, oxygen, phosphorous and calcium weight percentages on root surfaces following SRP using manual curettes with and without laser irradiation at both output energies. Laser irradiation after SRP with curettes yielded rougher surfaces compared to the use of curettes alone. Conclusion: Although laser irradiation yielded rougher surfaces, root surfaces were not significantly different in terms of chemical composition following SRP using manual curettes with and without Er:YAG laser irradiation. Er:YAG laser can be safely used as an adjunct to curettes for SRP. PMID:28652898

Surface morphology of laser tracks used for forming the non-smooth biomimetic unit of 3Cr2W8V steel under different processing parameters

International Nuclear Information System (INIS)

Zhang Zhihui; Zhou Hong; Ren Luquan; Tong Xin; Shan Hongyu; Li Xianzhou

2008-01-01

Aiming to form the high quality of non-smooth biomimetic unit, the influence of laser processing parameters (pulse energy, pulse duration, frequency and scanning speed in the present work) on the surface morphology of scanned tracks was studied based on the 3Cr2W8V die steel. The evolution of the surface morphology was explained according to the degree of melting and vaporization of surface material, and the trend of mean surface roughness and maximum peak-to-valley height. Cross-section morphology revealed the significant microstructural characteristic of the laser-treated zone used for forming the functional zone on the biomimetic surface. Results showed that the combination of pulse energy and pulse duration plays a major role in determining the local height difference on the irradiated surface and the occurrence of melting or vaporization. While frequency and scanning speed have a minor effect on the change of the surface morphology, acting mainly by the different overlapping amount and overlapping mode. The mechanisms behind these influences were discussed, and schematic drawings were introduced to describe the mechanisms

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

Directory of Open Access Journals (Sweden)

Mitul Kumar Mishra

2013-01-01

Full Text Available 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

Observation of interactions between hydrophilic ionic liquid and water on wet agar gels by FE-SEM and its mechanism

International Nuclear Information System (INIS)

Takahashi, Chisato; Shirai, Takashi; Fuji, Masayoshi

2012-01-01

Highlights: ► The mechanism of SEM observation of agar gel using ionic liquid was investigated. ► Weak hydrogen bond between ionic liquid and water exist even under vacuum condition. ► Ionic liquid binding ability with water is useful for observing wet material using FE-SEM. ► We could optimize the water concentrations of sample of IL and wet material mixtures. ► SEM observation of fine morphology of agar gel in optimum water content. - Abstract: In the present study, an attempt is made to understand the mechanism of field emission electron microscopy (FE-SEM) observation of wet agar gel using a typical hydrophilic ionic liquid (IL) 1-butyl-3-methylimidazolium tetrafluoroborate; [BMIM][BF 4 ]. The IL interaction with water molecules within agar gel during sample preparation condition for FE-SEM observation was investigated using Raman spectroscopy. Results showed that water molecules within agar gel form weak hydrogen bond such as BF 4 − ⋯HOH⋯BF 4 − by interaction with BF 4 − of IL, and, it remained stable even under vacuum condition at 60 °C, 24 h. This interaction was found to be helpful for IL displacement of the water molecules within agar gel. From this study, it was found that the exact morphology of gel materials in FE-SEM condition can be observed by optimization of water concentrations of IL and gel mixtures. Thus, using IL, agar gel or any other material under wet condition can be observed without drying in FE-SEM chamber, and, present result gives an insight to the mechanism of FE-SEM observation of agar gel using IL without any conducting coating.

In vitro study of hydroxy apatite and enamel powder fused in human enamel by Nd:YAG laser; Estudo in vitro da fusao de hidroxiapatita e esmalte em superficies de esmalte humano pelo laser de Nd:YAg

Energy Technology Data Exchange (ETDEWEB)

Ferrreira, Marcus Vinicius Lucas

2000-07-01

The aim of this study was to evaluate the effects of pulsed Nd:YAG (1064 nm) laser irradiation on hydroxyapatite and enamel powder fusion. This laser beam is not well absorbed by this two compounds for this reason they were mixed with vegetal coal to increase the absorption of the laser beam. Fifteen enamel flat surfaces and six occlusal enamel surfaces were prepared with three different substances: hydroxyapatite mixed with vegetal coal (3:1 in weigh); enamel powder mixed with vegetal coal (3:1 in weigh); vegetal coal. The occlusal surfaces were utilized to determine if the compounds could seal pits and fissures. Flat surfaces were utilized to determine fusion of hydroxyapatite and enamel powder. All samples were irradiated with Nd:YAG laser with the parameters: 80 mJ, 15 Hz, 1,2 W, 100 {mu}s pulse-width, 131,1 J/cm{sup 2}. Laser beam was delivered to the samples with a 300 {mu}m diameter fiber optic. Morphology of the irradiated surfaces were examined by scanning electron microscopy (SEM). The compounds with hydroxyapatite and enamel powder were fused to enamel surfaces. Only partial pits and fissures sealing could be observed. (author)

Porous niobium coatings fabricated with selective laser melting on titanium substrates: Preparation, characterization, and cell behavior.

Science.gov (United States)

Zhang, Sheng; Cheng, Xian; Yao, Yao; Wei, Yehui; Han, Changjun; Shi, Yusheng; Wei, Qingsong; Zhang, Zhen

2015-08-01

Nb, an expensive and refractory element with good wear resistance and biocompatibility, is gaining more attention as a new metallic biomaterial. However, the high price of the raw material, as well as the high manufacturing costs because of Nb's strong oxygen affinity and high melting point have limited the widespread use of Nb and its compounds. To overcome these disadvantages, porous Nb coatings of various thicknesses were fabricated on Ti substrate via selective laser melting (SLM), which is a 3D printing technique that uses computer-controlled high-power laser to melt the metal. The morphology and microstructure of the porous Nb coatings, which had pores ranging from 15 to 50 μm in size, were characterized with scanning electron microscopy (SEM). The average hardness of the coating, which was measured with the linear intercept method, was 392±37 HV. In vitro tests of the porous Nb coating which was monitored with SEM, immunofluorescence, and CCK-8 counts of cells, exhibited excellent cell morphology, attachment, and growth. The simulated body fluid test also proved the bioactivity of the Nb coating. Therefore, these new porous Nb coatings could potentially be used for enhanced early biological fixation to bone tissue. In addition, this study has shown that SLM technique could be used to fabricate coatings with individually tailored shapes and/or porosities from group IVB and VB biomedical metals and their alloys on stainless steel, Co-Cr, and other traditional biomedical materials without wasting raw materials. Copyright © 2015 Elsevier B.V. All rights reserved.

Effect of LASER Irradiation on the Shear Bond Strength of Zirconia Ceramic Surface to Dentin

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Sima Shahabi

2012-09-01

Full Text Available Background and Aims: Reliable bonding between tooth substrate and zirconia-based ceramic restorations is always of great importance. The laser might be useful for treatment of ceramic surfaces. The aim of the present study was to investigate the effect of laser irradiation on the shear bond strength of zirconia ceramic surface to dentin. Materials and Methods: In this experimental in vitro study, 40 Cercon zirconia ceramic blocks were fabricated. The surface treatment was performed using sandblasting with 50-micrometer Al2O3, CO2 laser, or Nd:YAG laser in each test groups. After that, the specimens were cemented to human dentin with resin cement. The shear bond strength of ceramics to dentin was determined and failure mode of each specimen was analyzed by stereo-microscope and SEM investigations. The data were statistically analyzed by one-way analysis of variance and Tukey multiple comparisons. The surface morphology of one specimen from each group was investigated under SEM. Results: The mean shear bond strength of zirconia ceramic to dentin was 7.79±3.03, 9.85±4.69, 14.92±4.48 MPa for CO2 irradiated, Nd:YAG irradiated, and sandblasted specimens, respectively. Significant differences were noted between CO2 (P=0.001 and Nd:YAG laser (P=0.017 irradiated specimens with sandblasted specimens. No significant differences were observed between two laser methods (P=0.47. The mode of bond failure was predominantly adhesive in test groups (CO2 irradiated specimens: 75%, Nd:YAG irradiated: 66.7%, and sandblasting: 41.7%. Conclusion: Under the limitations of the present study, surface treatment of zirconia ceramics using CO2 and Nd:YAG lasers was not able to produce adequate bond strength with dentin surfaces in comparison to sandblasting technique. Therefore, the use of lasers with the mentioned parameters may not be recommended for the surface treatment of Cercon ceramics.

Structural, morphological and optical properties of LiCo0.5Ni0.45Ag0.05O2 thin films

Science.gov (United States)

Haider, Adawiya J.; AL-Rsool, Rusul Abed; AL-Tabbakh, Ahmed A.; Al-Gebori, Abdul Nasser M.; Mohamed, Aliaa

2018-05-01

Pulsed Laser Deposition (PLD) method has been successfully used for the synthesized of nano-crystalline cathode m aterial LiCo0.5Ni0.45Ag0.05O2 (LCNAO) thin film. LCNAO Ferromagnetic using pulsed Nd-YAG laser with wavelength (λ = 532 nm) and duration (10 ns) and energy fluence (1.4 J/cm2) with different substrate temperature (100, 200, 300) ˚C and O2 pressure at 10 mbar. The structural, morphological and optical properties of the films were determined by X-ray Diffraction (XRD), Scan Electron Microscopy (SEM), Atomic Force microscope (AFM) and UV-VIS spectroscopy respectively. It is observed that partial layer to spinel transformation takes place during post annealing and the average particle size of the LiCo0.5Ni0.45Ag0.05O2 is found to be (1-12) nm from SEM measurement. Finally the optical properties of the thin films have been studied at different Substrate temperature. It found the energy gap decreases from 4.2 to 3.8 eV when the substrate's temperature increasing from 100° C into 300 °C of the LCNAO films. These mean that the optical quality of LCNAO films is improved due to the increase in crystalline size and reduction of defect sites.

Morphology, microstructure, and mechanical properties of laser-welded joints in GH909 alloy

Energy Technology Data Exchange (ETDEWEB)

Wang, Chunming; Cai, Yuanzheng; Hu, Chongjing; Zhang, Xiong; Yan, Fei; Hu, Xiyuan [Huazhong University of Science and Technology, Wuhan (China)

2017-05-15

The experimental laser welding of GH909 alloy was conducted in this study. The morphology, microstructure, and mechanical properties of laser-welded joints were analyzed by scanning electron microscopy, energy diffraction spectroscopy, and other techniques. Results revealed that the microstructure of the welded joints mainly consisted of tiny cellular structures, dendritic structures, and equiaxed crystals. Pores appeared in the interdendritic regions because of the insufficient local feeding of molten metal during solidification. Nb segregation in the heat-affected zone caused liquation cracking, whereas C segregation further induced the formation of carbide precipitates along the grain boundaries during the welding thermal cycle. The instability of the keyhole significantly promoted the escape of the metal vapor/plasma from the hole; as a result, porosity defects formed in the weld. The average tensile strength of the test joints was 756 MPa, which is 93.1 % of that of the base metal. The average microhardness of the weld zone (250 HV) was higher than that of the GH909 alloy substrate (208 HV), peaking at 267 HV. Microcracks appeared along the grain boundaries, proving that the grain boundaries were the weakest areas in the joint.

Estudo da topografia e da osseointegração de implante de titânio sob ação do LASER, com ou sem deposição de hidroxiapatita, em coelhos

OpenAIRE

Sisti, Karin Ellen

2011-01-01

Objetivo: Estudar a topografia a osseointegração de implantes de titânio sob ação do LASER de alta intensidade com e sem deposição química de hidroxiapatita, em coelhos. Método: Foram utilizados 30 coelhos albinos que receberam em suas tíbias 3 tipos de superfície de implantes: grupo controle(GI) implantes usinados, grupo(GII) irradiado LASER(Yb), e grupo irradiado e depositado hidroxiapatita pelo método biomimético(GIII). Após os períodos de avaliações (30 e 60 dias) os implantes foram subme...

Architecture-dependent distribution of Mesopores in steamed Zeolite crystals as visualized by FIB-SEM Tomography

NARCIS (Netherlands)

Karwacki, L.|info:eu-repo/dai/nl/304824283; de Winter, D.A.M.|info:eu-repo/dai/nl/304838616; Aramburo, L.R.; Lebbink, M.N.|info:eu-repo/dai/nl/304834246; Post, J.A.|info:eu-repo/dai/nl/074120050; Drury, M.R.|info:eu-repo/dai/nl/304829315; Weckhuysen, B.M.|info:eu-repo/dai/nl/285484397

2011-01-01

Break on through: Steaming-induced mesopores of individual ZSM-5 crystals were studied by a combination of focused ion beam (FIB) and scanning electron microscopy (SEM) tomography (see picture). In this manner, quantitative insight into the width, length, morphology, and distribution of mesopores

Structural and electronic characterization of 355 nm laser-crystallized silicon: Interplay of film thickness and laser fluence

International Nuclear Information System (INIS)

Semler, Matthew R.; Swenson, Orven F.; Hoey, Justin M.; Guruvenket, Srinivasan; Gette, Cody R.; Hobbie, Erik K.

2014-01-01

We present a detailed study of the laser crystallization of amorphous silicon thin films as a function of laser fluence and film thickness. Silicon films grown through plasma-enhanced chemical vapor deposition were subjected to a Q-switched, diode-pumped solid-state laser operating at 355 nm. The crystallinity, morphology, and optical and electronic properties of the films are characterized through transmission and reflectance spectroscopy, resistivity measurements, Raman spectroscopy, X-ray diffraction, atomic force microscopy, and optical and scanning-electron microscopy. Our results reveal a unique surface morphology that strongly couples to the electronic characteristics of the films, with a minimum laser fluence at which the film properties are optimized. A simple scaling model is used to relate film morphology to conductivity in the laser-processed films

Analysis of polymer grafted inside the porous hydrogel using confocal laser scanning microscopy

Directory of Open Access Journals (Sweden)

2007-04-01

Full Text Available Graft polymerization of glycidyl methacrylate onto the pore surface of polyacrylamide macroporous gel was implemented in DMSO-aqueous solution using diperiodatocuprate(III complexes as an initiator. The grafting densities up to 410% were achieved. The graft polymerization was confirmed by gravimetrical methods and FTIR. The graft polymerization of polymer inside the pores of the macroporous gel resulted in increased flow resistance through the gel matrix. The distribution of grafted polymer on the gel pore surface material was studied by scanning electron microscopy (SEM and confocal laser scanning microscopy (CLSM. CLSM is an alternative method for studying morphology of gel surface with grafted polymer having the advantages over the SEM allowing to investigate the distribution of grafted polymer inside the hydrogel in a native hydrated state. The microscopic techniques demonstrated uneven distribution of the grafted polymer inside the gel pores as a result of initiating the graft polymerization by insoluble initiator deposited on the pore surface.

Production of microscale particles from fish bone by gas flow assisted laser ablation

International Nuclear Information System (INIS)

Boutinguiza, M.; Lusquinos, F.; Comesana, R.; Riveiro, A.; Quintero, F.; Pou, J.

2007-01-01

Recycled wastes from fish and seafood can constitute a source of precursor material for different applications in the biomedical field such as bone fillers or precursor material for bioceramic coatings to improve the osteointegration of metallic implants. In this work, fish bones have been used directly as target in a laser ablation system. A pulsed Nd:YAG laser was used to ablate the fish bone material and a transverse air flow was used to extract the ablated material out of the interaction zone. The particles collected at a filter were in the micro and nanoscale range. The morphology as well as the composition of the obtained particles were characterized by scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDX) and transmission electron microscopy (TEM). The results reveal that the composition of the analyzed particles is similar to that of the inorganic part of the fish bone

Production of microscale particles from fish bone by gas flow assisted laser ablation

Science.gov (United States)

Boutinguiza, M.; Lusquiños, F.; Comesaña, R.; Riveiro, A.; Quintero, F.; Pou, J.

2007-12-01

Recycled wastes from fish and seafood can constitute a source of precursor material for different applications in the biomedical field such as bone fillers or precursor material for bioceramic coatings to improve the osteointegration of metallic implants. In this work, fish bones have been used directly as target in a laser ablation system. A pulsed Nd:YAG laser was used to ablate the fish bone material and a transverse air flow was used to extract the ablated material out of the interaction zone. The particles collected at a filter were in the micro and nanoscale range. The morphology as well as the composition of the obtained particles were characterized by scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDX) and transmission electron microscopy (TEM). The results reveal that the composition of the analyzed particles is similar to that of the inorganic part of the fish bone.

Effect of organoclay incorporation on dental resin morphology

International Nuclear Information System (INIS)

Oliveira, Nadja M.S.; Reis, Romulo P.B.; Leite, Itamara F.; Morais, Crislene R.S.; Silva, Suedina M.L.

2009-01-01

The objective of the present work was to incorporate nanosilicates in commercial dental resins in order to prepare dental nanocomposites competitive as commercial nanoparticulates dental resins. Thus, a silicate, Cloisite 20A (C20A), was incorporated in a microhybrid dental resin (Z100) and morphological properties of the nanocomposites evaluated as a function of the incorporation method and the amount of filler employed. The samples were characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM). The XRD results evidence that nanocomposites have been obtained and according to SEM results, the morphology of microhybrid resin was modified when C20A nanoparticulate was incorporated improve the size distribution and reduce the agglomeration of the particles. (author)

Advanced SEM imaging

International Nuclear Information System (INIS)

Joy, D. C.; Newbury, D. E.

1998-01-01

The scanning electron microscope (SEM) represents the most promising tool for metrology, defect review, and for the analysis of ULSI structures, but both fundamental problems such as electron-solid interactions, and practical considerations such as electron-optical constraints, are now setting a limit to performance. This paper examines the directions in which an advanced SEM might be developed to overcome these constraints. The SEM also offers considerable promise as a tool for the high spatial resolution X-ray microanalysis, especially for those situations where a thin cross-section is not practical and first surface analysis is required. The ways in which this capability can be incorporated in an advanced SEM are examined

Advanced SEM imaging

International Nuclear Information System (INIS)

Joy, D.C.; Newbury, D.E.; Newbury, D.E.

1998-01-01

The scanning electron microscope (SEM) represents the most promising tool for metrology, defect review, and for the analysis of ULSI structures, but both fundamental problems such as electron-solid interactions, and practical considerations such as electron-optical constraints, are now setting a limit to performance. This paper examines the directions in which an advanced SEM might be developed to overcome these constraints. The SEM also offers considerable promise as a tool for the high spatial resolution X-ray microanalysis, especially for those situations where a thin cross-section is not practical and first surface analysis is required. The ways in which this capability can be incorporated in an advanced SEM are examined. copyright 1998 American Institute of Physics

Morphology of resin-dentin interfaces after Er,Cr:YSGG laser and acid etching preparation and application of different bonding systems.

Science.gov (United States)

Beer, Franziska; Buchmair, Alfred; Körpert, Wolfram; Marvastian, Leila; Wernisch, Johann; Moritz, Andreas

2012-07-01

The goal of this study was to show the modifications in the ultrastructure of the dentin surface morphology following different surface treatments. The stability of the adhesive compound with dentin after laser preparation compared with conventional preparation using different bonding agents was evaluated. An Er,Cr:YSGG laser and 36% phosphoric acid in combination with various bonding systems were used. A total of 100 caries-free human third molars were used in this study. Immediately after surgical removal teeth were cut using a band saw and 1-mm thick dentin slices were created starting at a distance of 4 mm from the cusp plane to ensure complete removal of the enamel. The discs were polished with silicon carbide paper into rectangular shapes to a size of 6 × 4 mm (±0,2 mm).The discs as well as the remaining teeth stumps were stored in 0.9% NaCl at room temperature. The specimens were divided into three main groups (group I laser group, group II etch group, group III laser and etch group) and each group was subdivided into three subgroups which were allocated to the different bonding systems (subgroup A Excite, subgroup B Scotchbond, subgroup C Syntac). Each disc and the corresponding tooth stump were treated in the same way. After preparation the bonding composite material was applied according to the manufacturers' guidelines in a hollow tube of 2 mm diameter to the disc as well as to the corresponding tooth stump. Shear bond strength testing and environmental scanning electron microscopy were used to assess the morphology and stability of the resin-dentin interface. The self-etching bonding system showed the highest and the most constant shear values in all three main groups, thus enabling etching with phosphoric acid after laser preparation to be avoided. Thus we conclude that laser preparation creates a surface texture that allows prediction of the quality of the restoration without the risk of negative influences during the following treatment steps. This

Nd:YAG laser irradiation on temporary teeth carious tissue using 12% diamine silver fluoride as a photo-absorber - a morphological study

International Nuclear Information System (INIS)

Calmon, Andrea de Avillez

2001-01-01

Since Nd:YAG laser radiation was first introduced in Dentistry various photo-absorbers were employed with the intent of improving its efficacy when used on dental carious tissue. The purpose of the present study was to analyze the influence of this radiation using Scanning and Optical microscopy over carious tissue of primary teeth using two photo-absorbers. 15 primary human teeth were used and, in each one, 3 cavity preparations were performed. Specimens were then submitted to an in vitro demineralizing environment during 18 days. Two of the cavities of each specimen were laser irradiated using the Nd:YAG laser with 60 mJ of energy per pulse, 10 Hz and average power of 0,6 W. The 12% diamine silver fluoride or the mineral coal were used as photo-absorbers. The third cavity of the specimens was used as a control and received no laser irradiation. Samples were transversally cut and the section analyzed by SEM and OM. Results showed that the 12% diamine silver fluoride is an efficient photo-absorber and, when used it the Nd:YAG laser, leading to melting and resolidification of the carious tissue. It can be concluded that the 12% diammine silver fluoride presents advantages over the mineral coal as a photo absorber when used in primary teeth as it promotes and improves the efficacy of laser irradiation. This substance also works as a barrier on the carie progression in deeper areas such as the infected and necrotic zones. (author)

Morphology and structural studies of WO{sub 3} films deposited on SrTiO{sub 3} by pulsed laser deposition

Energy Technology Data Exchange (ETDEWEB)

Kalhori, Hossein, E-mail: h.kalhori@ph.iut.ac.ir [School of Physics and CRANN, Trinity College, Dublin 2 (Ireland); Department of Physics, Isfahan University of Technology, Isfahan 84156-8311 (Iran, Islamic Republic of); Porter, Stephen B.; Esmaeily, Amir Sajjad; Coey, Michael [School of Physics and CRANN, Trinity College, Dublin 2 (Ireland); Ranjbar, Mehdi; Salamati, Hadi [Department of Physics, Isfahan University of Technology, Isfahan 84156-8311 (Iran, Islamic Republic of)

2016-12-30

Highlights: • Highly oriented WO{sub 3} stoichiometric films were determined using pulsed laser deposition method. • Effective parameters on thin films including temperature, oxygen partial pressure and laser energy fluency was studied. • A phase transition was observed in WO{sub 3} films at 700 °C from monoclinic to tetragonal. - Abstract: WO{sub 3} films have been grown by pulsed laser deposition on SrTiO{sub 3} (001) substrates. The effects of substrate temperature, oxygen partial pressure and energy fluence of the laser beam on the physical properties of the films were studied. Reflection high-energy electron diffraction (RHEED) patterns during and after growth were used to determine the surface structure and morphology. The chemical composition and crystalline phases were obtained by XPS and XRD respectively. AFM results showed that the roughness and skewness of the films depend on the substrate temperature during deposition. Optimal conditions were determined for the growth of the highly oriented films.

Femtosecond pulsed laser ablation of GaAs

International Nuclear Information System (INIS)

Trelenberg, T.W.; Dinh, L.N.; Saw, C.K.; Stuart, B.C.; Balooch, M.

2004-01-01

The properties of femtosecond-pulsed laser deposited GaAs nanoclusters were investigated. Nanoclusters of GaAs were produced by laser ablating a single crystal GaAs target in vacuum or in a buffer gas using a Ti-sapphire laser with a 150 fs minimum pulse length. For in-vacuum deposition, X-ray diffraction (XRD), scanning electron microscopy (SEM), and atomic force microscopy (AFM) revealed that the average cluster size was approximately 7 nm for laser pulse lengths between 150 fs and 25 ps. The average cluster size dropped to approximately 1.5 nm at a pulse length of 500 ps. It was also observed that film thickness decreased with increasing laser pulse length. A reflective coating, which accumulated on the laser admission window during ablation, reduced the amount of laser energy reaching the target for subsequent laser shots and developed more rapidly at longer pulse lengths. This observation indicates that non-stoichiometric (metallic) ablatants were produced more readily at longer pulse lengths. The angular distribution of ejected material about the target normal was well fitted to a bi-cosine distribution of cos 47 θ+ cos 4 θ for ablation in vacuum using 150 fs pulses. XPS and AES revealed that the vacuum-deposited films contained excess amorphous Ga or As in addition to the stoichiometric GaAs nanocrystals seen with XRD. However, films containing only the GaAs nanocrystals were produced when ablation was carried out in the presence of a buffer gas with a pressure in excess of 6.67 Pa. At buffer gas pressure on the order of 1 Torr, it was found that the stoichiometry of the ablated target was also preserved. These experiments indicate that both laser pulse length and buffer gas pressure play important roles in the formation of multi-element nanocrystals by laser ablation. The effects of gas pressure on the target's morphology and the size of the GaAs nanocrystals formed will also be discussed

Field emission scanning electron microscopy (FE-SEM) as an approach for nanoparticle detection inside cells

Czech Academy of Sciences Publication Activity Database

Havrdová, M.; Poláková, K.; Skopalík, J.; Vůjtek, M.; Mokdad, A.; Homolková, M.; Tuček, J.; Nebesářová, Jana; Zbořil, R.

2014-01-01

Roč. 67, DEC 2014 (2014), s. 149-154 ISSN 0968-4328 Institutional support: RVO:60077344 Keywords : Field emission scanning electronmicroscopy (FE-SEM) * Stem cells * Iron oxide nanoparticles * Cellular morphology * Endosomes * Cell uptake Subject RIV: FD - Oncology ; Hematology Impact factor: 1.988, year: 2014

Low power infrared laser modifies the morphology of lung affected with acute injury induced by sepsis

Science.gov (United States)

Sergio, L. P. S.; Trajano, L. A. S. N.; Thomé, A. M. C.; Mencalha, A. L.; Paoli, F.; Fonseca, A. S.

2018-06-01

Acute lung injury (ALI) is a potentially fatal disease characterized by uncontrolled hyperinflammatory responses in the lungs as a consequence of sepsis. ALI is divided into two sequential and time-dependent phases, exudative and fibroproliferative phases, with increased permeability of the alveolar barrier, causing edema and inflammation. However, there are no specific treatments for ALI. Low-power lasers have been successfully used in the resolution of acute inflammatory processes. The aim of this study was to evaluate the effects of low-power infrared laser exposure on alveolus and interalveolar septa of Wistar rats affected by ALI-induced by sepsis. Laser fluences, power, and the emission mode were those used in clinical protocols for the treatment of acute inflammation. Adult male Wistar rats were randomized into six groups: control, 10 J cm‑2, 20 J cm‑2, ALI, ALI  +  10 J cm‑2, and ALI  +  20 J cm‑2. ALI was induced by intraperitoneal Escherichia coli lipopolysaccharide (LPS). Lungs were removed and processed for hematoxylin–eosin staining. Morphological alterations induced by LPS in lung tissue were quantified by morphometry with a 32-point cyclic arcs test system in Stepanizer. Data showed that exposure to low-power infrared laser in both fluences reduced the thickening of interalveolar septa in lungs affected by ALI, increasing the alveolar space; however, inflammatory infiltrate was still observed. Our research showed that exposure to low-power infrared laser improves the lung parenchyma in Wistar rats affected by ALI, which could be an alternative approach for treatment of inflammatory lung injuries.

Correlation between Morphological, Optical and Electrical ...

African Journals Online (AJOL)

The scanning electron microscope (SEM) and atomic force microscope (AFM) were employed for the surface morphological measurements. The charge carrier concentrations, mobilities and AC resistivities were deduced from Drude's model. The DC resistivities were determined from the four-point probe measurements.

Morphological and Production Changes in Stressed Red Yeasts Monitored Using SEM and Raman Spectroscopy

Czech Academy of Sciences Publication Activity Database

Hrubanová, Kamila; Samek, Ota; Haroniková, A.; Bernatová, Silvie; Zemánek, Pavel; Márová, I.; Krzyžánek, Vladislav

2016-01-01

Roč. 22, S3 (2016), s. 1146-1147 ISSN 1431-9276 R&D Projects: GA MŠk(CZ) LO1212; GA MŠk ED0017/01/01; GA ČR(CZ) GA14-20012S; GA ČR(CZ) GA15-20645S Institutional support: RVO:68081731 Keywords : SEM * Raman spectroscopy Subject RIV: JA - Electronics ; Optoelectronics, Electrical Engineering Impact factor: 1.891, year: 2016

Enabling CD SEM metrology for 5nm technology node and beyond

Science.gov (United States)

Lorusso, Gian Francesco; Ohashi, Takeyoshi; Yamaguchi, Astuko; Inoue, Osamu; Sutani, Takumichi; Horiguchi, Naoto; Bömmels, Jürgen; Wilson, Christopher J.; Briggs, Basoene; Tan, Chi Lim; Raymaekers, Tom; Delhougne, Romain; Van den Bosch, Geert; Di Piazza, Luca; Kar, Gouri Sankar; Furnémont, Arnaud; Fantini, Andrea; Donadio, Gabriele Luca; Souriau, Laurent; Crotti, Davide; Yasin, Farrukh; Appeltans, Raf; Rao, Siddharth; De Simone, Danilo; Rincon Delgadillo, Paulina; Leray, Philippe; Charley, Anne-Laure; Zhou, Daisy; Veloso, Anabela; Collaert, Nadine; Hasumi, Kazuhisa; Koshihara, Shunsuke; Ikota, Masami; Okagawa, Yutaka; Ishimoto, Toru

2017-03-01

The CD SEM (Critical Dimension Scanning Electron Microscope) is one of the main tools used to estimate Critical Dimension (CD) in semiconductor manufacturing nowadays, but, as all metrology tools, it will face considerable challenges to keep up with the requirements of the future technology nodes. The root causes of these challenges are not uniquely related to the shrinking CD values, as one might expect, but to the increase in complexity of the devices in terms of morphology and chemical composition as well. In fact, complicated threedimensional device architectures, high aspect ratio features, and wide variety of materials are some of the unavoidable characteristics of the future metrology nodes. This means that, beside an improvement in resolution, it is critical to develop a CD SEM metrology capable of satisfying the specific needs of the devices of the nodes to come, needs that sometimes will have to be addressed through dramatic changes in approach with respect to traditional CD SEM metrology. In this paper, we report on the development of advanced CD SEM metrology at imec on a variety of device platform and processes, for both logic and memories. We discuss newly developed approaches for standard, IIIV, and germanium FinFETs (Fin Field Effect Transistors), for lateral and vertical nanowires (NW), 3D NAND (three-dimensional NAND), STT-MRAM (Spin Transfer Magnetic Torque Random-Access Memory), and ReRAM (Resistive Random Access Memory). Applications for both front-end of line (FEOL) and back-end of line (BEOL) are developed. In terms of process, S/D Epi (Source Drain Epitaxy), SAQP (Self-Aligned Quadruple Patterning), DSA (Dynamic Self-Assembly), and EUVL (Extreme Ultraviolet Lithography) have been used. The work reported here has been performed on Hitachi CG5000, CG6300, and CV5000. In terms of logic, we discuss here the S/D epi defect classification, the metrology optimization for STI (Shallow Trench Isolation) Ge FinFETs, the defectivity of III-V STI Fin

Formation of silver nanoparticles inside a soda-lime glass matrix in the presence of a high intensity Ar+ laser beam

International Nuclear Information System (INIS)

Niry, M. D.; Khalesifard, H. R.; Mostafavi-Amjad, J.; Ahangary, A.; Azizian-Kalandaragh, Y.

2012-01-01

Formation and motion of the silver nanoparticles inside an ion-exchanged soda-lime glass in the presence of a focused high intensity continuous wave Ar + laser beam (intensity: 9.2 x 10 4 W/cm 2 ) have been studied in here. One-dimensional diffusion equation has been used to model the diffusion of the silver ions into the glass matrix, and a two-dimensional reverse diffusion model has been introduced to explain the motion of the silver clusters and their migration toward the glass surface in the presence of the laser beam. The results of the mentioned models were in agreement with our measurements on thickness of the ion-exchange layer by means of optical microscopy and recorded morphology of the glass surface around the laser beam axis by using a Mirau interferometer. SEM micrographs were used to extract the size distribution of the migrated silver particles over the glass surface.

Fabrication of metallic surfaces with long-term superhydrophilic property using one-stop laser method

International Nuclear Information System (INIS)

Guan, Y.C.; Luo, F.F.; Lim, G.C.; Hong, M.H.; Zheng, H.Y.; Qi, Bojin

2015-01-01

Highlights: • One-stop laser method is presented to fabricate superhydrophilic surface on metals. • Wettability study shows the longest superhydrophilic duration as more than 1 month. • Water-soluble compounds, polar functional groups and dual-scale structures were formed. • Surface roughness shows an amplification effect of the wetting behavior. - Abstract: A simple method for fabricating stable superhydrophilic surface at metallic substrates is reported. This technique comprises irradiating the surface with multiple laser pulses. Surface wettability can be taylored through controlling laser parameters and processing conditions. The substrates were selected as aluminum alloy and stainless steel. Physical morphology and chemical composition of laser-textured surfaces were characterized by SEM, XPS, and 3D profiler measurements. Results showed that the longest wettability duration was achieved as more than 1 month for stainless steel and more than 200 h for Al alloy, respectively. The possible mechanism of hydrophilic behavior of laser-textured surfaces was discussed. The effect of surface topography on superhydrophilicity property was also evaluated. This study presents a promising method in fabricating long-term superhydrophilic surfaces, which is useful for improving adhesion or achieving water-assisted flow in industrial applications as well as developing cell-based technologies in biomedical applications

In vitro study of hydroxy apatite and enamel powder fused in human enamel by Nd:YAG laser

International Nuclear Information System (INIS)

Ferrreira, Marcus Vinicius Lucas

2000-01-01

The aim of this study was to evaluate the effects of pulsed Nd:YAG (1064 nm) laser irradiation on hydroxyapatite and enamel powder fusion. This laser beam is not well absorbed by this two compounds for this reason they were mixed with vegetal coal to increase the absorption of the laser beam. Fifteen enamel flat surfaces and six occlusal enamel surfaces were prepared with three different substances: hydroxyapatite mixed with vegetal coal (3:1 in weigh); enamel powder mixed with vegetal coal (3:1 in weigh); vegetal coal. The occlusal surfaces were utilized to determine if the compounds could seal pits and fissures. Flat surfaces were utilized to determine fusion of hydroxyapatite and enamel powder. All samples were irradiated with Nd:YAG laser with the parameters: 80 mJ, 15 Hz, 1,2 W, 100 μs pulse-width, 131,1 J/cm 2 . Laser beam was delivered to the samples with a 300 μm diameter fiber optic. Morphology of the irradiated surfaces were examined by scanning electron microscopy (SEM). The compounds with hydroxyapatite and enamel powder were fused to enamel surfaces. Only partial pits and fissures sealing could be observed. (author)

Antibacterial properties of laser spinning glass nanofibers.

Science.gov (United States)

Echezarreta-López, M M; De Miguel, T; Quintero, F; Pou, J; Landin, M

2014-12-30

A laser-spinning technique has been used to produce amorphous, dense and flexible glass nanofibers of two different compositions with potential utility as reinforcement materials in composites, fillers in bone defects or scaffolds (3D structures) for tissue engineering. Morphological and microstructural analyses have been carried out using SEM-EDX, ATR-FTIR and TEM. Bioactivity studies allow the nanofibers with high proportion in SiO2 (S18/12) to be classified as a bioinert glass and the nanofibers with high proportion of calcium (ICIE16) as a bioactive glass. The cell viability tests (MTT) show high biocompatibility of the laser spinning glass nanofibers. Results from the antibacterial activity study carried out using dynamic conditions revealed that the bioactive glass nanofibers show a dose-dependent bactericidal effect on Sthaphylococcus aureus (S. aureus) while the bioinert glass nanofibers show a bacteriostatic effect also dose-dependent. The antibacterial activity has been related to the release of alkaline ions, the increase of pH of the medium and also the formation of needle-like aggregates of calcium phosphate at the surface of the bioactive glass nanofibers which act as a physical mechanism against bacteria. The antibacterial properties give an additional value to the laser-spinning glass nanofibers for different biomedical applications, such as treating or preventing surgery-associated infections. Copyright © 2014 Elsevier B.V. All rights reserved.

Experimental study on 800 nm femtosecond laser ablation of fused silica in air and vacuum

Energy Technology Data Exchange (ETDEWEB)

Xu, Shi-zhen, E-mail: xusz@uestc.edu.cn [School of Physical Electronics, University of Electronic Science and Technology of China, Chengdu 610054 (China); Research Center of Laser Fusion, China Academy of Engineering Physics, Mianyang 621900 (China); Yao, Cai-zhen; Liao, Wei [Research Center of Laser Fusion, China Academy of Engineering Physics, Mianyang 621900 (China); Yuan, Xiao-dong, E-mail: yxd66my@163.com [Research Center of Laser Fusion, China Academy of Engineering Physics, Mianyang 621900 (China); Wang, Tao [School of Physical Electronics, University of Electronic Science and Technology of China, Chengdu 610054 (China); Research Center of Laser Fusion, China Academy of Engineering Physics, Mianyang 621900 (China); Zu, Xiao-tao [School of Physical Electronics, University of Electronic Science and Technology of China, Chengdu 610054 (China)

2016-10-15

Ablation rates of fused silica were studied as a function of femtosecond laser pulse fluences (0.7–41 J/cm{sup 2}) in air and vacuum. The experiment was conducted by using a Ti:sapphire laser that emits radiation at 800 nm with a pulse width of 35 fs and a repetition rate of 10 Hz. The morphology and ablation depth of laser-induced damage crater were evaluated by using optical microscopy and scanning electron microscopy (SEM). Ablation rates were calculated from the depth of craters induced by multiple laser pulses. Results showed that two ablation regimes, i.e. non-thermal and thermal ablation co-existed in air and vacuum at low and moderate fluences. A drop of ablation rate was observed at high fluence (higher than 9.5 J/cm{sup 2}) in air. While in vacuum, the ablation rate increased continuously with the increasing of laser fluence and much higher than that in air. The drop of ablation rate observed at high fluence in air was due to the strong defocusing effects associated with the non-equilibrium ionization of air. Furthermore, the laser-induced damage threshold (LIDT), which was determined from the relationship between crater area and the logarithm of laser energy, was found to depend on the number of incident pulses on the same spot, and similar phenomenon was observed in air and vacuum.

Analysis of Indium Tin Oxide Film Using Argon Fluroide (ArF) Laser-Excited Atomic Fluorescence of Ablated Plumes.

Science.gov (United States)

Ho, Sut Kam; Garcia, Dario Machado

2017-04-01

A two-pulse laser-excited atomic fluorescence (LEAF) technique at 193 nm wavelength was applied to the analysis of indium tin oxide (ITO) layer on polyethylene terephthalate (PET) film. Fluorescence emissions from analytes were induced from plumes generated by first laser pulse. Using this approach, non-selective LEAF can be accomplished for simultaneous multi-element analysis and it overcomes the handicap of strict requirement for laser excitation wavelength. In this study, experimental conditions including laser fluences, times for gating and time delay between pulses were optimized to reveal high sensitivity with minimal sample destruction and penetration. With weak laser fluences of 100 and 125 mJ/cm 2 for 355 and 193 nm pulses, detection limits were estimated to be 0.10% and 0.43% for Sn and In, respectively. In addition, the relation between fluorescence emissions and number of laser shots was investigated; reproducible results were obtained for Sn and In. It shows the feasibility of depth profiling by this technique. Morphologies of samples were characterized at various laser fluences and number of shots to examine the accurate penetration. Images of craters were also investigated using scanning electron microscopy (SEM). The results demonstrate the imperceptible destructiveness of film after laser shot. With such weak laser fluences and minimal destructiveness, this LEAF technique is suitable for thin-film analysis.

Whole mount nuclear fluorescent imaging: convenient documentation of embryo morphology.

Science.gov (United States)

Sandell, Lisa L; Kurosaka, Hiroshi; Trainor, Paul A

2012-11-01

Here, we describe a relatively inexpensive and easy method to produce high quality images that reveal fine topological details of vertebrate embryonic structures. The method relies on nuclear staining of whole mount embryos in combination with confocal microscopy or conventional wide field fluorescent microscopy. In cases where confocal microscopy is used in combination with whole mount nuclear staining, the resulting embryo images can rival the clarity and resolution of images produced by scanning electron microscopy (SEM). The fluorescent nuclear staining may be performed with a variety of cell permeable nuclear dyes, enabling the technique to be performed with multiple standard microscope/illumination or confocal/laser systems. The method may be used to document morphology of embryos of a variety of organisms, as well as individual organs and tissues. Nuclear stain imaging imposes minimal impact on embryonic specimens, enabling imaged specimens to be utilized for additional assays. Copyright © 2012 Wiley Periodicals, Inc.

Raman-in-SEM, a multimodal and multiscale analytical tool: performance for materials and expertise.

Science.gov (United States)

Wille, Guillaume; Bourrat, Xavier; Maubec, Nicolas; Lahfid, Abdeltif

2014-12-01

The availability of Raman spectroscopy in a powerful analytical scanning electron microscope (SEM) allows morphological, elemental, chemical, physical and electronic analysis without moving the sample between instruments. This paper documents the metrological performance of the SEMSCA commercial Raman interface operated in a low vacuum SEM. It provides multiscale and multimodal analyses as Raman/EDS, Raman/cathodoluminescence or Raman/STEM (STEM: scanning transmission electron microscopy) as well as Raman spectroscopy on nanomaterials. Since Raman spectroscopy in a SEM can be influenced by several SEM-related phenomena, this paper firstly presents a comparison of this new tool with a conventional micro-Raman spectrometer. Then, some possible artefacts are documented, which are due to the impact of electron beam-induced contamination or cathodoluminescence contribution to the Raman spectra, especially with geological samples. These effects are easily overcome by changing or adapting the Raman spectrometer and the SEM settings and methodology. The deletion of the adverse effect of cathodoluminescence is solved by using a SEM beam shutter during Raman acquisition. In contrast, this interface provides the ability to record the cathodoluminescence (CL) spectrum of a phase. In a second part, this study highlights the interest and efficiency of the coupling in characterizing micrometric phases at the same point. This multimodal approach is illustrated with various issues encountered in geosciences. Copyright © 2014 Elsevier Ltd. All rights reserved.

Improvement of the optical and morphological properties of microlens arrays fabricated by laser using a sol–gel coating

International Nuclear Information System (INIS)

Nieto, Daniel; Gómez-Varela, Ana Isabel; Martín, Yolanda Castro; O’Connor, Gerard M.; Flores-Arias, María Teresa

2015-01-01

Highlights: • Microlens arrays were fabricated on soda-lime glass using a Ti:Sapphire laser. • A SiO 2 coating prepared via sol–gel route was used to improve the microlens quality. • The sol–gel coating was deposited at the microlens top surface using a dip coating. • Optical properties of the microlenses were improved by the coating. - Abstract: We present a simple, repeatable and non-contaminant method to improve the optical and morphological properties of microlens arrays. It consists on depositing hybrid SiO 2 (TEOS, MTES) coatings via sol–gel route onto microlens arrays fabricated using a Ti:Sapphire Femtosecond Amplitude Systems S-pulse HP laser operating at 1030 nm. The deposited silica sol–gel layer reduces the surface roughness (quantified as the root mean square) and increases the quality of the interstices between the microlenses generated by the ablation process, thus improving the contrast and homogeneity of the foci of the microlens array. The proposed technique allows us to obtain microlenses with a diameter in the range of 15–20 μm and a depth of 1.5–15 μm. For the characterization of the micro-optical structures, the UV–visible spectroscopy, spectral ellipsometry, confocal microscopy and beam profilometry were used. The proof-of-principle presented in this paper can be used to improve the optical and morphological properties of micro-optical systems of different nature by tailoring the parameters involved in both the laser ablation and sol–gel processes comprising the starting materials, solvent and catalysts nature and concentration, hydrolysis ratio, aging time and/or deposition conditions

Improvement of the optical and morphological properties of microlens arrays fabricated by laser using a sol–gel coating

Energy Technology Data Exchange (ETDEWEB)

Nieto, Daniel, E-mail: daniel.nieto@usc.es [Microoptics and GRIN Optics Group, Applied Physics Department, Faculty of Physics, University of Santiago de Compostela, Santiago de Compostela E15782 (Spain); Gómez-Varela, Ana Isabel [Microoptics and GRIN Optics Group, Applied Physics Department, Faculty of Physics, University of Santiago de Compostela, Santiago de Compostela E15782 (Spain); Martín, Yolanda Castro [Instituto de Cerámica y Vidrio (CSIC), Kelsen 5, Campus de Cantoblanco, 28049 Madrid (Spain); O’Connor, Gerard M. [School of Physics, National Centre for Laser Applications, National University of Ireland, University Road, Galway (Ireland); Flores-Arias, María Teresa, E-mail: maite.flores@usc.es [Microoptics and GRIN Optics Group, Applied Physics Department, Faculty of Physics, University of Santiago de Compostela, Santiago de Compostela E15782 (Spain)

2015-10-01

Highlights: • Microlens arrays were fabricated on soda-lime glass using a Ti:Sapphire laser. • A SiO{sub 2} coating prepared via sol–gel route was used to improve the microlens quality. • The sol–gel coating was deposited at the microlens top surface using a dip coating. • Optical properties of the microlenses were improved by the coating. - Abstract: We present a simple, repeatable and non-contaminant method to improve the optical and morphological properties of microlens arrays. It consists on depositing hybrid SiO{sub 2} (TEOS, MTES) coatings via sol–gel route onto microlens arrays fabricated using a Ti:Sapphire Femtosecond Amplitude Systems S-pulse HP laser operating at 1030 nm. The deposited silica sol–gel layer reduces the surface roughness (quantified as the root mean square) and increases the quality of the interstices between the microlenses generated by the ablation process, thus improving the contrast and homogeneity of the foci of the microlens array. The proposed technique allows us to obtain microlenses with a diameter in the range of 15–20 μm and a depth of 1.5–15 μm. For the characterization of the micro-optical structures, the UV–visible spectroscopy, spectral ellipsometry, confocal microscopy and beam profilometry were used. The proof-of-principle presented in this paper can be used to improve the optical and morphological properties of micro-optical systems of different nature by tailoring the parameters involved in both the laser ablation and sol–gel processes comprising the starting materials, solvent and catalysts nature and concentration, hydrolysis ratio, aging time and/or deposition conditions.

Strong morphological and crystallographic texture and resulting yield strength anisotropy in selective laser melted tantalum

International Nuclear Information System (INIS)

Thijs, Lore; Montero Sistiaga, Maria Luz; Wauthle, Ruben; Xie, Qingge; Kruth, Jean-Pierre; Van Humbeeck, Jan

2013-01-01

Selective laser melting (SLM) makes use of a high energy density laser beam to melt successive layers of metallic powders in order to create functional parts. The energy density of the laser is high enough to melt refractory metals like Ta and produce mechanically sound parts. Furthermore, the localized heat input causes a strong directional cooling and solidification. Epitaxial growth due to partial remelting of the previous layer, competitive growth mechanism and a specific global direction of heat flow during SLM of Ta result in the formation of long columnar grains with a 〈1 1 1〉 preferential crystal orientation along the building direction. The microstructure was visualized using both optical and scanning electron microscopy equipped with electron backscattered diffraction and the global crystallographic texture was measured using X-ray diffraction. The thermal profile around the melt pool was modeled using a pragmatic model for SLM. Furthermore, rotation of the scanning direction between different layers was seen to promote the competitive growth. As a result, the texture strength increased to as large as 4.7 for rotating the scanning direction 90° every layer. By comparison of the yield strength measured by compression tests in different orientations and the averaged Taylor factor calculated using the viscoplastic self-consistent model, it was found that both the morphological and crystallographic texture observed in SLM Ta contribute to yield strength anisotropy

The effect of laser irradiation on electrical and structural properties of ZnO thin films

Directory of Open Access Journals (Sweden)

P Kameli

2013-03-01

Full Text Available  In this paper, ZnO thin film was prepared by sol-gel process on glass substrates. The deposited films were dried at 100 and 240 ˚C and then annealed at 300, 400 and 500 ˚C. The two-probe measurement showed that resistance of as-prepared films is very high. The KrF excimer (λ=248 nm laser irradiation with 1000 pulses, frequency of 1 Hz and 90 mJ/cm2 energy on surface of film resulted in the reduction of the films electrical resistance. X-ray diffraction (XRD patterns confirmed the improved hexagonal wurtzite structure of film, and AFM and FE-SEM analyses showed regular and spherical grain was formed on the surface. The particle size was increased from ~10 to ~30 nm after leaser irradiation. Generally, it was showed that electrical, structural and morphological properties of films improve considerably by laser irradiation.

Micro/nanostructures formation by femtosecond laser surface processing on amorphous and polycrystalline Ni{sub 60}Nb{sub 40}

Energy Technology Data Exchange (ETDEWEB)

Peng, Edwin, E-mail: edwin.peng@huskers.unl.edu [Department of Mechanical and Materials Engineering, University of Nebraska-Lincoln, Lincoln, NE 68588 (United States); Tsubaki, Alfred; Zuhlke, Craig A. [Department of Electrical and Computer Engineering, University of Nebraska-Lincoln, Lincoln, NE 68588 (United States); Wang, Meiyu [Department of Mechanical and Materials Engineering, University of Nebraska-Lincoln, Lincoln, NE 68588 (United States); Bell, Ryan [Department of Electrical and Computer Engineering, University of Nebraska-Lincoln, Lincoln, NE 68588 (United States); Lucis, Michael J. [Department of Mechanical and Materials Engineering, University of Nebraska-Lincoln, Lincoln, NE 68588 (United States); Anderson, Troy P.; Alexander, Dennis R. [Department of Electrical and Computer Engineering, University of Nebraska-Lincoln, Lincoln, NE 68588 (United States); Gogos, George; Shield, Jeffrey E. [Department of Mechanical and Materials Engineering, University of Nebraska-Lincoln, Lincoln, NE 68588 (United States)

2017-02-28

Highlights: • Femtosecond laser processing of glass-forming Ni{sub 60}Nb{sub 40} produce surface structures. • Cross sectioning, imaging, & TEM sample preparation with dual-beam SEM. • Low laser fluence surface structures’ form by ablation. • High laserfluence surface structures form by ablation and fluid flow. - Abstract: Femtosecond laser surface processing is a technology that can be used to functionalize many surfaces, imparting specialized properties such as increased broadband optical absorption or superhydrophilicity/superhydrophobicity. In this study, two unique classes of surface structures, below surface growth (BSG) and above surface growth (ASG) mounds, were formed by femtosecond laser surface processing on amorphous and polycrystalline Ni{sub 60}Nb{sub 40} with two different grain sizes. Cross sectional imaging of these mounds revealed thermal evidence of the unique formation processes for each class of surface structure. BSG mounds formed on all three substrates using the same laser parameters had similar surface morphology. The microstructures in the mounds were unaltered compared with the substrate before laser processing, suggesting their formation was dominated by preferential valley ablation. ASG mounds had similar morphology when formed on the polycrystalline Ni{sub 60}Nb{sub 40} substrates with 100 nm and 2 μm grain size. However, the ASG mounds had significantly wider diameter and higher peak-to-valley heights when the substrate was amorphous Ni{sub 60}Nb{sub 40}. Hydrodynamic melting was primarily responsible for ASG mound formation. On amorphous Ni{sub 60}Nb{sub 40} substrates, the ASG mounds are most likely larger due to lower thermal diffusivity. There was clear difference in growth mechanism of femtosecond laser processed BSG and ASG mounds, and grain size does not appear to be a factor.

SEM Characterization of an Irradiated Monolithic U-10Mo Fuel Plate

International Nuclear Information System (INIS)

Keiser, D.D. Jr.; Jue, J.F.; Robinson, A.B.

2010-01-01

Results of scanning electron microscopy (SEM) characterization of irradiated U-7Mo dispersion fuel plates with differing amounts of matrix Si have been reported. However, to date, no results of SEM analysis of irradiated U-Mo monolithic fuel plates have been reported. This paper describes the first SEM characterization results for an irradiated monolithic U-10Mo fuel plate. Two samples from this fuel plate were characterized. One sample was produced from the low-flux side of the fuel plate, and another was produced at the high-flux side of the fuel plate. This characterization focused on the microstructural features present at the U-10Mo foil/cladding interface, particularly the interaction zone that had developed during fabrication and irradiation. In addition, the microstructure of the foil itself was investigated, along with the morphology of the observed fission gas bubbles. It was observed that a Si-rich interaction layer was present at the U-10Mo foil/cladding interface that exhibited relatively good irradiation behavior, and within the U-10Mo foil the microstructural features differed in some respects from what is typically seen in the U-Mo powders of an irradiated dispersion fuel.

Investigation on Nano-Self-Lubricant Coating Synthesized by Laser Cladding and Ion Sulfurization

Directory of Open Access Journals (Sweden)

Meiyan Li

2015-01-01

Full Text Available The composite processing between laser cladding and low temperature (300°C ion sulfurization was applied to prepare wear resistant and self-lubricating coating. The microstructure, morphology, phase composition, valence states, and wear resistance of the composite coating were investigated by scanning electron microscopy (SEM, atomic force microscope (AFM, X-ray diffraction (XRD, X-ray photoelectron spectroscope (XPS, and friction and wear apparatus. The results indicate that the laser cladding Ni-based coatings and the maximum hardness of 46.5 HRC were obtained when the percent of pure W powder was 10%, composed of columnar dendrites crystals and ultrafine dendritic structure. After ion sulfurization at 300°C for 4 h, the loose and porous composite coating is formed with nanograins and the granularity of all grains is less than 100 nm, which consists of γ-(Fe, Ni, M23C6 carbides, FeS, FeS2, and WS2. Furthermore, the wear resistance of the composite coating is better than the laser cladding Ni55 + 10%W coating, and the friction coefficient and mass losses under the conditions of dry and oil lubrication are lower than those of laser cladding Ni55 + 10%W coating.

Effects of morphology and wavelength on the measurement accuracy of soot volume fraction by laser extinction

Science.gov (United States)

Wang, Ya-fei; Huang, Qun-xing; Wang, Fei; Chi, Yong; Yan, Jian-hua

2018-01-01

A novel method to evaluate the quantitative effects of soot morphology and incident wavelength on the measurement accuracy of soot volume fraction, by the laser extinction (LE) technique is proposed in this paper. The results indicate that the traditional LE technique would overestimate soot volume fraction if the effects of morphology and wavelength are not considered. Before the agglomeration of isolated soot primary particles, the overestimation of the LE technique is in the range of 2-20%, and rises with increasing primary particle diameter and with decreasing incident wavelength. When isolated primary particles are agglomerated into fractal soot aggregates, the overestimation would exceed 30%, and rise with increasing primary particle number per soot aggregate, fractal dimension and fractal prefactor and with decreasing incident wavelength to a maximum value of 55%. Finally, based on these results above, the existing formula of the LE technique gets modified, and the modification factor is 0.65-0.77.

In vitro study of morphological and chemical modification threshold of bovine dental enamel irradiated by the holmium laser; Estudo in vitro das alteracoes morfologicas e quimicas do esmalte dental bovino irradiado pelo laser de holmio

Energy Technology Data Exchange (ETDEWEB)

Eduardo, Patricia Lerro de Paula

2001-07-01

The aim of this study is to investigate the Ho:YLF laser effects on the dental enamel surface with regards to its morphology, thermal variations during its irradiation in the pulp chamber and its increased resistance to demineralization through quantitative analysis of calcium and phosphorous atoms reactive concentrations in samples. Twenty samples of bovine enamel were used and divided in four groups: control - acidulated phosphate fluoride (APF) application followed by demineralization treatment with lactic acid; irradiation with Ho:YLF laser (100 J/cm{sup 2}) followed by APF topic application and demineralization treatment with lactic acid; irradiation with Ho:YLF laser (350 J/cm{sup 2}) followed by APF topic application and demineralization treatment with lactic acid: and irradiation with Ho:YLF laser ( 450 J/cm{sup 2}) followed by APF topic application and demineralization treatment with lactic acid. Ali samples were quantified according to their calcium and phosphorous atoms relative concentrations before and after the treatments above. X-Ray fluorescence spectrochemical analysis and scanning electron microscopy were carried out. It was observed an increase on the calcium and phosphorous atoms concentration ratio and therefore the enamel demineralization reduction as a result of the lactic acid treatment in the samples irradiated with the holmium laser followed by the APF application. In order to evaluate the feasibility of this study for clinical purposes, morphological changes caused by the holmium laser irradiation were analyzed. Such modifications were characterized by melted and re-solidified regions of the enamel with consequent changes on its permeability and solubility. Temperature changes of ten human pre-molars teeth irradiated with 350 J/cm{sup 2} and 450 J/cm{sup 2} were also monitored in the pulp chamber in real time. Temperature increases over 4,20 C did not occur. The results obtained from this study along with the results from previous

Assessment of engineered surfaces roughness by high-resolution 3D SEM photogrammetry

Energy Technology Data Exchange (ETDEWEB)

Gontard, L.C., E-mail: lionelcg@gmail.com [Departamento de Ciencia de los Materiales e Ingeniería Metalúrgica y Química Inorgánica, Universidad de Cádiz, Puerto Real 11510 (Spain); López-Castro, J.D.; González-Rovira, L. [Departamento de Ciencia de los Materiales e Ingeniería Metalúrgica y Química Inorgánica, Escuela Superior de Ingeniería, Laboratorio de Corrosión, Universidad de Cádiz, Puerto Real 11519 (Spain); Vázquez-Martínez, J.M. [Departamento de Ingeniería Mecánica y Diseño Industrial, Escuela Superior de Ingeniería, Universidad de Cádiz, Puerto Real 11519 (Spain); Varela-Feria, F.M. [Servicio de Microscopía Centro de Investigación, Tecnología e Innovación (CITIUS), Universidad de Sevilla, Av. Reina Mercedes 4b, 41012 Sevilla (Spain); Marcos, M. [Departamento de Ingeniería Mecánica y Diseño Industrial, Escuela Superior de Ingeniería, Universidad de Cádiz, Puerto Real 11519 (Spain); and others

2017-06-15

Highlights: • We describe a method to acquire a high-angle tilt series of SEM images that is symmetrical respect to the zero tilt of the sample stage. The method can be applied in any SEM microscope. • Using the method, high-resolution 3D SEM photogrammetry can be applied on planar surfaces. • 3D models of three surfaces patterned with grooves are reconstructed with high resolution using multi-view freeware photogrammetry software as described in LC Gontard et al. Ultramicroscopy, 2016. • From the 3D models roughness parameters are measured • 3D SEM high-resolution photogrammetry is compared with two conventional methods used for roughness characetrization: stereophotogrammetry and contact profilometry. • It provides three-dimensional information with high-resolution that is out of reach for any other metrological technique. - Abstract: We describe a methodology to obtain three-dimensional models of engineered surfaces using scanning electron microscopy and multi-view photogrammetry (3DSEM). For the reconstruction of the 3D models of the surfaces we used freeware available in the cloud. The method was applied to study the surface roughness of metallic samples patterned with parallel grooves by means of laser. The results are compared with measurements obtained using stylus profilometry (PR) and SEM stereo-photogrammetry (SP). The application of 3DSEM is more time demanding than PR or SP, but it provides a more accurate representation of the surfaces. The results obtained with the three techniques are compared by investigating the influence of sampling step on roughness parameters.

SEM analysis for irradiated materials

International Nuclear Information System (INIS)

Liu Xiaosong; Yao Liang

2008-06-01

A radiation-proof Scanning Electron Microscope (SEM) system is introduced. It has been widely used in various areas. For analyzing radioactive samples, normal SEM system needs lots of alterations. Based on KYKY-2800B SEM, the sample room, belt line, operating table and aerator were updated. New radiation-proof SEM system has used to analytic surface contaminated samples and RPV materials samples. An elementary means of SEM analysis for radioactive samples was studied, and this examination supported some available references for further irradiated fuel researches. (authors)

Laser cladding of nickel base alloy on SS316L for improved wear and corrosion behaviour

International Nuclear Information System (INIS)

Awasthi, Reena; Kushwaha, R.P.; Chandra, Kamlesh; Viswanadham, C.S.; Srivastava, D.; Dey, G.K.; Limaye, P.K.

2013-01-01

Laser cladding by an Nd:YAG laser was employed to deposit Ni base alloy (Ni-Mo-Cr-Si) on stainless steel-316 L substrate. The resulting defect-free clad with minimum dilution of the substrate was characterized by optical microscopy, scanning electron microscopy, X-ray diffraction and Vickers microhardness test. Dry sliding wear of the cladding and the substrate was evaluated using a ball-on-plate reciprocating wear tester against different counter bodies (WC and 52100 Cr steel). The reciprocating sliding wear resistance of the coating was evaluated as a function of the normal load, keeping the sliding amplitude and sliding speed constant. Wear mechanisms were analyzed by observation of wear track morphology using SEM-EDS. The electrochemical corrosion behavior of clad layer was studied in reducing environment (HCl) to estimate the general corrosion resistance of the laser clad layer in comparison with the substrate SS-316L. The clad layer showed higher wear resistance under reducing condition than that of the substrate material stainless steel 316L. (author)

Effect of WOW process parameters on morphology and burst release of FITC-dextran loaded PLGA microspheres.

Science.gov (United States)

Mao, Shirui; Xu, Jing; Cai, Cuifang; Germershaus, Oliver; Schaper, Andreas; Kissel, Thomas

2007-04-04

Using fluorescein isothiocyanate labeled dextran (FITC-dextran 40, FD40) as a hydrophilic model compound, microspheres were prepared by a WOW double emulsion technique. Influence of process parameters on microsphere morphology and burst release of FD40 from PLGA microspheres was studied. Internal morphology of microspheres was investigated by stereological method via cryo-cutting technique and scanning electron microscopy (SEM). Drug distribution in microspheres was observed with confocal laser scanning microscopy (CLSM). Polymer nature (RG503 and RG503H) had significant influence on the micro-morphology of microspheres. Increase in continuous water phase volume (W2) led to increased surface porosity but decreased internal porosity. By increasing PVA concentration in the continuous phase from 0.1 to 1%, particle size changed marginally but burst release decreased from 12.2 to 5.9%. Internal porosity of microspheres decreased considerably with increasing polymer concentration. Increase in homogenization speed during the primary emulsion preparation led to decreased internal porosity. Burst release decreased with increasing drug loading but increased with drug molecular weight. Drug distribution in microspheres depended on preparation method. The porosity of microspheres decreased with time in the diffusion stage, but internal morphology had no influence on the release behavior in the bioerosion stage. In summary, surface porosity and internal morphology play a significant role in the release of hydrophilic macromolecules from biodegradable microspheres in the initial release phase characterized by pore diffusion.

Influence of a pulsed CO2 laser operating at 9.4 μm on the surface morphology, reflectivity, and acid resistance of dental enamel below the threshold for melting

Science.gov (United States)

Kim, Jin Wan; Lee, Raymond; Chan, Kenneth H.; Jew, Jamison M.; Fried, Daniel

2017-02-01

Below the threshold for laser ablation, the mineral phase of enamel is converted into a purer phase hydroxyapatite with increased acid resistance. Studies suggest the possibility of achieving the conversion without visible surface alteration. In this study, changes in the surface morphology, reflectivity, and acid resistance were monitored with varying irradiation intensity. Bovine enamel specimens were irradiated using a CO2 laser operating at 9.4 μm with a Gaussian spatial beam profile-1.6 to 3.1 mm in diameter. After laser treatment, samples were subjected to demineralization to simulate the acidic intraoral conditions of dental decay. The resulting demineralization and erosion were assessed using polarization-sensitive optical coherence tomography, three-dimensional digital microscopy, and polarized light microscopy. Distinct changes in the surface morphology and the degree of inhibition were found within the laser-treated area in accordance with the laser intensity profile. Subtle visual changes were noted below the melting point for enamel that appear to correspond to thresholds for denaturation of the organic phase and thermal decomposition of the mineral phase. There was significant protection from laser irradiation in areas in which the reflectivity was not increased significantly, suggesting that aesthetically sensitive areas of the tooth can be treated for caries prevention.

Morphology and phase structures of CW laser-induced oxide layers on iron surface with evolving reflectivity and colors

Energy Technology Data Exchange (ETDEWEB)

Wu, Taotao, E-mail: wutaotao@nint.ac.cn; Wang, Lijun; Wei, Chenghua; Zhou, Menglian; He, Minbo; Wu, Lixiong

2016-11-30

Highlights: • Firstly, iron samples with different color features were obtained by continuous wave laser irradiation depending on progressive durations. The real-time reflectivity and temperature of samples were measured. The color and the reflectivity evolution were related. They were both caused by the forming oxide films. • Secondly, laser-induced oxidation process of iron was studied by microscope, X-ray diffraction and Raman spectrum. The first formed magnetite made the surface reflectivity decline rapidly and caused the “positive feedback” effect because of molecular absorption. The later formed hematite oscillated the reflectivity by interference effect. • Lastly, the laser-induced oxide films were thin, orientated and badly crystallized. The Wagner oxidation theory was incapable of describing the non-isothermal and early stage oxidation process. So we emphasized that a precise oxidation model depending on the experiment and the optical constants of the laser-induced oxides must be studied. - Abstract: Laser-induced oxidation will change the laser reflectivity and color features of metal surface. Both changes can be theoretically calculated based on the oxidation kinetics and the optical constants of oxides. For the purpose of calculation, the laser-induced oxidation process of pure polycrystalline iron was studied. Samples with various color features were obtained by continuous wave Nd:YAG fiber laser (1.06 μm) irradiation depending on progressive durations in the intensity of 1.90 W/cm{sup 2}. The real-time reflectivity and temperature were measured with integral sphere and thermocouples. The irradiated surface morphology and phase structures were characterized by microscope, X-ray diffraction and Raman spectrum. It was found that the first formed magnetite made the surface reflectivity decline rapidly and caused the “positive feedback” effect because of molecular absorption. The later formed hematite oscillated the reflectivity by

Laser induced damage threshold on metallic surfaces during laser cleaning

CSIR Research Space (South Africa)

Labuschagne, K

2005-07-01

Full Text Available laser paint removal. Laser induced damage on 316L stainless steel was studied, with the target subjected to single and multiple pulse irradiations using a Q-switched Nd:YAG, with fluences between 0.15 and 11.8 J/cm2. Several different damage morphologies...

Analysis of microtraces in invasive traumas using SEM/EDS.

Science.gov (United States)

Vermeij, E J; Zoon, P D; Chang, S B C G; Keereweer, I; Pieterman, R; Gerretsen, R R R

2012-01-10

Scanning electron microscopy in combination with energy-dispersive X-ray spectrometry (SEM/EDS) is a proven forensic tool and has been used to analyze several kinds of trace evidence. A forensic application of SEM/EDS is the examination of morphological characteristics of tool marks that tools and instruments leave on bone. The microtraces that are left behind by these tools and instruments on the bone are, however, often ignored or not noticed at all. In this paper we will describe the use of SEM/EDS for the analysis of microtraces in invasive sharp-force, blunt-force and bone-hacking traumas in bone. This research is part of a larger multi-disciplinary approach in which pathologists, forensic anthropologists, toolmark and microtrace experts work together to link observed injuries to a suspected weapon or, in case of an unknown weapon, to indicate a group of objects that could have been used as a weapon. Although there are a few difficulties one have to consider, the method itself is rather simple and straightforward to apply. A sample of dry and clean bone is placed into the SEM sample chamber and brightness and contrast are set such that bone appears grey, metal appears white and organic material appears black. The sample is then searched manually to find relevant features. Once features are found their elemental composition is measured by an energy dispersive X-ray spectrometer (EDS). This method is illustrated using several cases. It is shown that SEM/EDS analysis of microtraces in bone is a valuable tool to get clues about an unknown weapon and can associate a specific weapon with injuries on the basis of appearance and elemental composition. In particular the separate results from the various disciplines are complementary and may be combined to reach a conclusion with a stronger probative value. This is not only useful in the courtroom but above all in criminal investigations when one have to know for what weapon or object to look for. Copyright © 2011

Influence of the laser pulse repetition rate and scanning speed on the morphology of Ag nanostructures fabricated by pulsed laser ablation of solid target in water

Science.gov (United States)

Nikolov, A. S.; Balchev, I. I.; Nedyalkov, N. N.; Kostadinov, I. K.; Karashanova, D. B.; Atanasova, G. B.

2017-11-01

Nanostructures of noble metal were produced by pulsed laser ablation in liquid. A solid Ag target was immersed in double distilled water and a CuBr laser in a master oscillator—power amplifier configuration oscillating at 511 nm and emitting pulses with duration of 30 ns at a repetition rate of up to 20 kHz was employed to produce different colloids. The impact was studied of the laser pulse repetition rate and the beam scanning speed on the morphology of the nanostructures formed. Further, the optical extinction spectra of the colloids in the UV/VIS range were measured and used to make an indirect assessment of the changes in the shape and size distribution of the nanostructures. The transmission values in the near UV range were used to estimate the efficiency of the ablation process under the different experimental conditions implemented. A visualization of the nanostructures was made possible by transmission electron microscopy (TEM). The structure and phase composition of the nanoparticles were studied by high-resolution transmission electron microscopy (HRTEM) and selected area electron diffraction (SAED), while the alteration of the target surface caused by the impact of the high-repetition-rate laser illumination was investigated by X-ray photoelectron spectroscopy (XPS). The optimal conditions were determined yielding the highest efficiency in terms of amount of ablated material.

The use of gamma irradiation in preparation of polybutadiene rubber nanopowder; Its effect on particle size, morphology and crosslink structure of the powder

Science.gov (United States)

Rezaei Abadchi, Majid; Jalali-Arani, Azam

2014-02-01

The aim of this work was the preparation and characterization of polybutadiene rubber (BR) powder by irradiating of rubber lattices using 60Co radiation and spray-drying of them at the appropriate condition. The influences of absorbed dose on the volume swelling ratio, molecular weight between crosslinks, gel fraction, and glass transition temperature of obtained powder were studied. Morphology, size and size distribution of rubber particles were examined by using scanning electron microscopy (SEM) and laser particle size analyzer (LPSA) technique, respectively. Results obtained by LPSA revealed that radiation has no effect on particle size of rubber latex but after drying, adherence properties of rubber particle causes increase in particle size of rubber powder, as shown in SEM photograph. Fourier transform infrared spectroscopy of rubber powders confirmed that with increasing the irradiation dose, characteristic peak corresponds to the >Cdbnd C< double bands decreased. Also Charlesby-Pinner equation was used to evaluate radiation yield.

Characterization of toners and inkjets by laser ablation spectrochemical methods and Scanning Electron Microscopy-Energy Dispersive X-ray Spectroscopy

Science.gov (United States)

Trejos, Tatiana; Corzo, Ruthmara; Subedi, Kiran; Almirall, José

2014-02-01

the advantage of being non-destructive to the sample in addition to providing imaging capabilities to further characterize toner samples by their particle morphology. Laser sampling methods resulted in an improvement of the discrimination between different sources with LIBS producing 89% discrimination and LA-ICP-MS resulting in 100% discrimination. In addition, a set of 21 black inkjet samples was examined by each method. The results show that SEM-EDS is not appropriate for inkjet examinations since their elemental composition is typically below the detection capabilities with only sulfur detected in this set, providing only 47.4% discrimination between possible comparison pairs. Laser sampling methods were shown to provide discrimination greater than 94% for this same inkjet set with false exclusion and false inclusion rates lower than 4.1% and 5.7%, for LA-ICP-MS and LIBS respectively. Overall these results confirmed the utility of the examination of printed documents by laser-based micro-spectrochemical methods. SEM-EDS analysis of toners produced a limited utility for discrimination within sources but was not an effective tool for inkjet ink discrimination. Both LA-ICP-MS and LIBS can be used in forensic laboratories to chemically characterize inks on documents and to complement the information obtained by conventional methods and enhance their evidential value.

Nd: YAG laser irradiation effects on structural and magnetic properties of Ni1+xZrxFe2-2xO4 nanoparticles

Science.gov (United States)

Saraf, Tukaram S.; Kounsalye, Jitendra S.; Birajdar, Shankar D.; Shamkuwar, N. R.

2018-05-01

The effect of 112 mJ Nd: YAG laser irradiation on structural, morphological, infrared and magnetic properties of Ni1+xZrxFe2-2xO4 spinel ferrite nanoparticles has been systematically investigated in the present work. The sol-gel auto combustion synthesis method was successfully executed for the synthesis of the present system. All the samples were characterized by X-ray diffraction technique (XRD), scanning electron microscopy (SEM) and infrared spectroscopy (IR) technique. The magnetic properties of the present samples were measured by pulse field hysteresis loop technique. All the properties were measured for laser irradiated samples as well, to understand the effect of irradiation on the properties. The single-phase cubic spinel structure was confirmed by X-ray diffraction patterns of all samples and the disordered structure was observed for irradiated samples. The two principle absorption bands in IR spectra also confirm the formation of the spinel structure. Spherical and agglomerated morphology was observed for Zr4+ substituted nickel ferrite, whereas scratched morphology was observed for the irradiated samples. The grain size confirms the nanocrystalline nature, the crystallite size also evident the same. The magnetic parameters decreased after Zr4+ ion doping and strongly influenced by the irradiation.

Multi-scale characteristics of coal structure by x-ray computed tomography (x-ray CT), scanning electron microscope (SEM) and mercury intrusion porosimetry (MIP)

Science.gov (United States)

Cai, Ting-ting; Feng, Zeng-chao; Zhou, Dong

2018-02-01

It is of great benefit to study the material and structural heterogeneity of coal for better understanding the coalbed methane (CBM) storage and enrichment. In this paper, multi-scale X-ray computed tomography (CT), scanning electron microscope (SEM) and mercury intrusion porosimetry (MIP) at multi scales were conducted to thoroughly study the material distribution, heterogeneity, pore development, porosity and permeability of coal. It is suitable and reasonable to divide the testing samples into three structural categories by average density and heterogeneity degree, and the meso structure in the three categories accords with the morphology on SEM images. The pore size distribution and pore development of each subsample cannot be correspondingly related to their respective structure category or morphology due to different observation scales, while the macro pore size development, accumulated macro pore volume and macro pores porosity accord with the meso structure category and morphology information by CT and SEM at the same scale very well. Given the effect of macro pores on permeability and the contribution of micro pores to CBM storage capacity, reservoirs with developed micro pores and macro pores may be the most suitable coal reservoir for CBM exploitation.

The morphology of durability issues in PEM fuel cells

International Nuclear Information System (INIS)

Kundu, S.; Fowler, M.; Simon, L.; Grot, S.

2004-01-01

'Full text:' The work presented here examines durability issues in PEM fuel cell materials by examining material morphology and linking morphological features to performance. Scanning electron microscope (SEM) techniques have been able to identify a variety of features on the catalyst layer, each with their own implication to the overall performance and durability of the membrane electrode assembly (MEA). These features include cracking, delamination of the catalyst layer, catalyst clustering, electrolyte clustering, and thickness variations. Links between several of these features and catalyst dispersion conditions was also examined, showing that how the material was manufactured influences the type of morphological features present. The SEM has also been used with accelerated aging techniques to closely examine aging of the gas diffusion layer (GDL). It can be shown that over time the GDL will loose its hydrophobic character and hence become more susceptible to flooding in a fuel cell. The impact of morphological changes were determined using fuel cell models and experimental work. The ultimate aim of this work is to provide material developers with the tools and knowledge necessary to design better materials and therefore bring fuel cells closer to commercialization. (author)

Investigation of laser cleaning on bronze cultural relics

International Nuclear Information System (INIS)

Ling, Xiulan; Wang, Gao; Zhang, Chen

2016-01-01

The effects of laser cleaning on the corrosion layers of bronze cultural relics were studied using a pulsed fiber laser. The laser cleaning threshold value of the corrosion layers was obtained. It was found that the corrosion layer was removed successfully by employing a laser fluence value of 0.32 J cm −2 and scanning for three times. To obtain experimental evidence, laser con-focal scanning microscopy, scanning electron microscopy (SEM), energy dispersive x-ray spectroscopy (EDS), laser induced breakdown spectroscopy (LIBS) and laser Raman spectroscopy were employed to investigate the cleaning efficiency of corrosion layers on specimens. (paper)

Size properties of colloidal nanoparticles produced by nanosecond pulsed laser ablation and studying the effects of liquid medium and laser fluence

International Nuclear Information System (INIS)

Mahdieh, Mohammad Hossein; Fattahi, Behzad

2015-01-01

Highlights: • Colloidal aluminum- and titanium-based nanoparticles fabricated by laser ablation. • Various liquid environments and laser fluences were applied as variable parameters. • Physical characteristics of liquid medium influence ablation process and nanoparticle formation. • Size properties of prepared nanoparticles depend on liquid medium and laser fluence. • Ablation of both metals in ethanol results in nanoparticles with smaller size. - Abstract: In this paper, pulsed laser ablation method was used for synthesis of colloidal nanoparticles of aluminum and titanium targets in distilled water, ethanol, and acetone as liquid environments. Ultraviolet–visible (UV–vis) absorption spectrophotometer and scanning electron microscope (SEM) were used for characterization of produced nanoparticles. Using image processing technique and analyzing the SEM images, nanoparticles’ mean size and size distribution were achieved. The results show that liquid medium has strong effect on size properties of produced nanoparticles. From the results, it was found that ablation of both metal targets in ethanol medium leads to formation of smaller size nanoparticles with narrower size distributions. The influence of laser fluence was also investigated. According to the results, higher laser fluence produces larger mean size nanoparticles with broader size distribution

Size properties of colloidal nanoparticles produced by nanosecond pulsed laser ablation and studying the effects of liquid medium and laser fluence

Energy Technology Data Exchange (ETDEWEB)

Mahdieh, Mohammad Hossein, E-mail: mahdm@iust.ac.ir; Fattahi, Behzad

2015-02-28

Highlights: • Colloidal aluminum- and titanium-based nanoparticles fabricated by laser ablation. • Various liquid environments and laser fluences were applied as variable parameters. • Physical characteristics of liquid medium influence ablation process and nanoparticle formation. • Size properties of prepared nanoparticles depend on liquid medium and laser fluence. • Ablation of both metals in ethanol results in nanoparticles with smaller size. - Abstract: In this paper, pulsed laser ablation method was used for synthesis of colloidal nanoparticles of aluminum and titanium targets in distilled water, ethanol, and acetone as liquid environments. Ultraviolet–visible (UV–vis) absorption spectrophotometer and scanning electron microscope (SEM) were used for characterization of produced nanoparticles. Using image processing technique and analyzing the SEM images, nanoparticles’ mean size and size distribution were achieved. The results show that liquid medium has strong effect on size properties of produced nanoparticles. From the results, it was found that ablation of both metal targets in ethanol medium leads to formation of smaller size nanoparticles with narrower size distributions. The influence of laser fluence was also investigated. According to the results, higher laser fluence produces larger mean size nanoparticles with broader size distribution.

308-nm excimer laser in endodontics

Science.gov (United States)

Liesenhoff, Tim

1992-06-01

Root canal preparation was performed on 20 extracted human teeth. After opening the coronal pulp, the root canals were prepared by 308 nm excimer laser only. All root canals were investigated under SEM after separation in the axial direction. By sagittal separation of the mandibles of freshly slaughtered cows, it was possible to get access to the tissues and irradiate under optical control. Under irradiation of excimer laser light, tissue starts to fluoresce. It was possible to demonstrate that each tissue (dentin, enamel, bone, pulpal, and connective tissue) has a characteristic spectral pattern. The SEM analyses showed that it is well possible to prepare root canals safely. All organic soft tissue has been removed by excimer laser irradiation. There was no case of via falsa. The simultaneous spectroscopic identification of the irradiated tissue provides a safe protection from overinstrumentation. First clinical trials on 20 patients suffering of chronical apical parodontitis have been carried out successfully.

Microprocessing of ITO and a-Si thin films using ns laser sources

Science.gov (United States)

Molpeceres, C.; Lauzurica, S.; Ocaña, J. L.; Gandía, J. J.; Urbina, L.; Cárabe, J.

2005-06-01

Selective ablation of thin films for the development of new photovoltaic panels and sensoring devices based on amorphous silicon (a-Si) is an emerging field, in which laser micromachining systems appear as appropriate tools for process development and device fabrication. In particular, a promising application is the development of purely photovoltaic position sensors. Standard p-i-n or Schottky configurations using transparent conductive oxides (TCO), a-Si and metals are especially well suited for these applications, appearing selective laser ablation as an ideal process for controlled material patterning and isolation. In this work a detailed study of laser ablation of a widely used TCO, indium-tin-oxide (ITO), and a-Si thin films of different thicknesses is presented, with special emphasis on the morphological analysis of the generated grooves. Excimer (KrF, λ = 248 nm) and DPSS lasers (λ = 355 and λ = 1064 nm) with nanosecond pulse duration have been used for material patterning. Confocal laser scanning microscopy (CLSM) and scanning electron microscopy (SEM) techniques have been applied for the characterization of the ablated grooves. Additionally, process parametric windows have been determined in order to assess this technology as potentially competitive to standard photolithographic processes. The encouraging results obtained, with well-defined ablation grooves having thicknesses in the order of 10 µm both in ITO and in a-Si, open up the possibility of developing a high-performance double Schottky photovoltaic matrix position sensor.

The UF GEM Research Center Mobile Terrestrial Laser Scanner System M-TLSS Applied to Beach Morphology Studies in St. Augustine, Florida.

Science.gov (United States)

Fernandez, J. C.; Shrestha, R. L.; Carter, W. E.; Slatton, C. K.; Singhania, A.

2006-12-01

The UF GEM Research Center is working towards developing a Mobile Terrestrial Laser Scanning System (M- TLSS). The core of the M-TLSS is a commercial 2-axis ground based laser scanner, Optech ILRIS-36D, which is capable of generating XYZ with laser intensity or RGB textured point clouds in a range from 3m to 1500m. The laser operates at a wavelength of 1535 nm. The sample separation can be adjusted down to 0.00115°, and the scanning speed is 2,000 points per second. The scanner is integrated to a mobile telescoping, rotating and tilting platform which is essentially a telescopic lift mounted on the back of a pick up truck. This provides up to 6 degrees of freedom for performing scanning operations. A scanner built-in 6 megapixel digital camera and a digital video camera provide the M-TLSS moving and still imagining capability. The applications of the M-TLSS data sets are numerous in both the fields of science and engineering. This paper will focus on the application of M-TLSS as a complement to ALSM in the study of beach morphology in the St. Augustine, Florida area. ALSM data covers a long stretch of beach with a moderate sample density of approximately 1 laser return per square meter, which enables the detection of submeter-scale changes in shoreline position and dune heights over periods of few months. The M-TLSS, on the other hand, can provide high density point clouds (centimeter scale point spacing) of smaller areas known to be highly prone to erosion. From these point clouds centimeter level surface grids are created. These grids will be compared with the ALSM data and with a time series of M-TLSS data over the same area to provide high resolution, short term beach erosion monitoring. Surface morphological parameters that will be compared among the ALSM and M-TLSS data sets include shoreline position and gradients and standard deviations of elevations on cross- shore transects.

Structural, morphological and electronic properties of pulsed laser grown Eu2O3 thin films

Science.gov (United States)

Kumar, Sandeep; Prakash, Ram; Choudhary, R. J.; Phase, D. M.

2018-05-01

Herein, we report the growth, structural, morphological and electronic properties of Europium sesquioxide (Eu2O3) thin films on Si [1 0 0] substrate using pulsed laser deposition technique. The films were deposited at ˜750 °C substrate temperature while the oxygen partial pressure (OPP) was varied (vacuum,˜1 mTorr, ˜10 mTorr and ˜300 mTorr). X-ray diffraction results confirm the single phase cubic structure of the film grown at ˜300 mTorr. The XRD results are also supported by the Raman's spectroscopy results. Eu-3d XPS core level spectra confirms the dominant contributions from the "3+" states of Eu in the film.

SEM characterization of an irradiated monolithic U-10Mo fuel plate

International Nuclear Information System (INIS)

Keiser, D.D. Jr.; Jue, J.F.; Robinson, A.B.; Finlay, M.R.

2010-01-01

Results of scanning electron microscopy (SEM) characterization of irradiated U-7Mo dispersion fuel plates with differing amounts of matrix Si have been reported. However, to date, no results of SEM analysis of irradiated U-Mo monolithic fuel plates have been reported. This paper describes the first SEM characterization results for an irradiated monolithic U-10Mo fuel plate. Two samples from this fuel plate were characterized. One sample was produced from the low-flux side of the fuel plate, and another was produced at the high-flux side of the fuel plate. This characterization focused on the microstructural features present at the U-10Mo foil/AA6061 cladding interface, particularly the interaction zone that had developed during fabrication and any continued development during irradiation. In addition, the microstructure of the foil itself was investigated, along with the morphology of the observed fission gas bubbles. It was observed that a Si-rich interaction layer was present at the U-10Mo foil/cladding interface that exhibited relatively good irradiation behavior, and within the U-10Mo foil the microstructural features differed in some respects from what is typically seen in the U-7Mo powders of an irradiated dispersion fuel. (author)

Laser cladding Co-based alloy/SiCp composite coatings on IF steel

International Nuclear Information System (INIS)

Li Mingxi; He Yizhu; Sun Guoxiong

2004-01-01

Hardfacing coatings, made of Co-Cr-W-Ni-Si alloy + 20% SiCp, deposited by laser cladding on IF steel is introduced. Cross-section of such coatings has been examined to reveal their microstructure using optical microscope, scanning electron microscope (SEM) and X-ray diffractometer (XRD). MM-200 type wear tester is used to examine wear resistance of the coatings. The results showed that SiCp is dissolved completely during laser cladding process under this conditions, the primary phase γ-Co dendrite and Si 2 W, CoWSi, Cr 3 Si, CoSi 2 formed by C, Si reacting with other elements existed in the coatings. There existed some crystallization morphologies in different regions, such as planar (at the interface), followed cellular and dendrite crystallization from interface to the surface. The direction of solidification changes from one direction perpendicular to interface to multi-directions at the central and upper regions of the clad. The results also showed that the wear resistance of the clad improved by adding SiCp

Nanoscale surface characterization using laser interference microscopy

Science.gov (United States)

Ignatyev, Pavel S.; Skrynnik, Andrey A.; Melnik, Yury A.

2018-03-01

Nanoscale surface characterization is one of the most significant parts of modern materials development and application. The modern microscopes are expensive and complicated tools, and its use for industrial tasks is limited due to laborious sample preparation, measurement procedures, and low operation speed. The laser modulation interference microscopy method (MIM) for real-time quantitative and qualitative analysis of glass, metals, ceramics, and various coatings has a spatial resolution of 0.1 nm for vertical and up to 100 nm for lateral. It is proposed as an alternative to traditional scanning electron microscopy (SEM) and atomic force microscopy (AFM) methods. It is demonstrated that in the cases of roughness metrology for super smooth (Ra >1 nm) surfaces the application of a laser interference microscopy techniques is more optimal than conventional SEM and AFM. The comparison of semiconductor test structure for lateral dimensions measurements obtained with SEM and AFM and white light interferometer also demonstrates the advantages of MIM technique.

Production of stable superhydrophilic surfaces on 316L steel by simultaneous laser texturing and SiO2 deposition

Science.gov (United States)

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

2018-01-01

Superhydrophilic surfaces with liquid contact angles of less than 5 ° have attracted much interest in practical applications including self-cleaning, cell manipulation, adhesion enhancement, anti-fogging, fluid flow control and evaporative cooling. Standard laser metal texturing method often result in unstable wetting characteristics, i.e. changing from super hydrophilic to hydrophobic in a few days or weeks. In this paper, a simple one step method is reported for fabricating a stable superhydrophilic metallic surface that lasted for at least 6 months. Here, 316L stainless steel substrates were textured using a nanosecond laser with in-situ SiO2 deposition. Morphology and chemistry of laser-textured surfaces were characterised using SEM, XRD, XPS and an optical 3D profiler. Static wettability analysis was carried out over a period of 6 months after the laser treatment. The effect of surface roughness on wettability was also studied. Results showed that the wettability of the textured surfaces could be controlled by changing the scanning speed of laser beam and number of passes. The main reason for the realisation of the stable superhydrophilic surface is the combination of the melted glass particles mainly Si and O with that of stainless steel in the micro-textured patterns. This study presents a useful method

Single-particle coherent diffractive imaging with a soft x-ray free electron laser: towards soot aerosol morphology

Science.gov (United States)

Bogan, Michael J.; Starodub, Dmitri; Hampton, Christina Y.; Sierra, Raymond G.

2010-10-01

The first of its kind, the Free electron LASer facility in Hamburg, FLASH, produces soft x-ray pulses with unprecedented properties (10 fs, 6.8-47 nm, 1012 photons per pulse, 20 µm diameter). One of the seminal FLASH experiments is single-pulse coherent x-ray diffractive imaging (CXDI). CXDI utilizes the ultrafast and ultrabright pulses to overcome resolution limitations in x-ray microscopy imposed by x-ray-induced damage to the sample by 'diffracting before destroying' the sample on sub-picosecond timescales. For many lensless imaging algorithms used for CXDI it is convenient when the data satisfy an oversampling constraint that requires the sample to be an isolated object, i.e. an individual 'free-standing' portion of disordered matter delivered to the centre of the x-ray focus. By definition, this type of matter is an aerosol. This paper will describe the role of aerosol science methodologies used for the validation of the 'diffract before destroy' hypothesis and the execution of the first single-particle CXDI experiments being developed for biological imaging. FLASH CXDI now enables the highest resolution imaging of single micron-sized or smaller airborne particulate matter to date while preserving the native substrate-free state of the aerosol. Electron microscopy offers higher resolution for single-particle analysis but the aerosol must be captured on a substrate, potentially modifying the particle morphology. Thus, FLASH is poised to contribute significant advancements in our knowledge of aerosol morphology and dynamics. As an example, we simulate CXDI of combustion particle (soot) morphology and introduce the concept of extracting radius of gyration of fractal aggregates from single-pulse x-ray diffraction data. Future upgrades to FLASH will enable higher spatially and temporally resolved single-particle aerosol dynamics studies, filling a critical technological need in aerosol science and nanotechnology. Many of the methodologies described for FLASH will

Single-particle coherent diffractive imaging with a soft x-ray free electron laser: towards soot aerosol morphology

International Nuclear Information System (INIS)

Bogan, Michael J; Starodub, Dmitri; Hampton, Christina Y; Sierra, Raymond G

2010-01-01

The first of its kind, the Free electron LASer facility in Hamburg, FLASH, produces soft x-ray pulses with unprecedented properties (10 fs, 6.8-47 nm, 10 12 photons per pulse, 20 μm diameter). One of the seminal FLASH experiments is single-pulse coherent x-ray diffractive imaging (CXDI). CXDI utilizes the ultrafast and ultrabright pulses to overcome resolution limitations in x-ray microscopy imposed by x-ray-induced damage to the sample by 'diffracting before destroying' the sample on sub-picosecond timescales. For many lensless imaging algorithms used for CXDI it is convenient when the data satisfy an oversampling constraint that requires the sample to be an isolated object, i.e. an individual 'free-standing' portion of disordered matter delivered to the centre of the x-ray focus. By definition, this type of matter is an aerosol. This paper will describe the role of aerosol science methodologies used for the validation of the 'diffract before destroy' hypothesis and the execution of the first single-particle CXDI experiments being developed for biological imaging. FLASH CXDI now enables the highest resolution imaging of single micron-sized or smaller airborne particulate matter to date while preserving the native substrate-free state of the aerosol. Electron microscopy offers higher resolution for single-particle analysis but the aerosol must be captured on a substrate, potentially modifying the particle morphology. Thus, FLASH is poised to contribute significant advancements in our knowledge of aerosol morphology and dynamics. As an example, we simulate CXDI of combustion particle (soot) morphology and introduce the concept of extracting radius of gyration of fractal aggregates from single-pulse x-ray diffraction data. Future upgrades to FLASH will enable higher spatially and temporally resolved single-particle aerosol dynamics studies, filling a critical technological need in aerosol science and nanotechnology. Many of the methodologies described for FLASH will

Characterization of the morphology of co-extruded, thermoplastic/rubber multi-layer tapes

International Nuclear Information System (INIS)

L'Abee, R.M.A.; Vissers, A.M.J.T.; Goossens, J.G.P.; Spoelstra, A.B.; Duin, M. van

2009-01-01

Tapes with alternating semi-crystalline thermoplastic/rubber layers with thicknesses varying from 100 nm up to several μm were prepared by multi-layer co-extrusion. The variation in layer thickness was obtained by varying the thermoplastic/rubber feed ratio. A systematic study on the use of various microscopy techniques to visualize the morphology of the layered systems is presented. The relatively large length scales and the sample preparation make optical microscopy (OM) unsuitable to study the morphology of the multi-layer tapes. Although excellent contrast between the thermoplastic and rubber layers can be obtained, the usually applied, relatively large magnifications limit the use of transmission electron microscopy (TEM) and atomic force microscopy (AFM) to small sample areas. The large range of applicable magnifications makes scanning electron microscopy (SEM) the most suitable technique to study the morphology of the multi-layer tapes. The sample preparation for SEM with a secondary electron (SE) detector is often based on the removal of one of the components, which may induce changes in the morphology. SEM with a back-scattered electron (BSE) detector is a very convenient method to study the morphology over a wide range of length scales, where the contrast between the different layers can be enhanced by chemical staining. Finally, the nucleation behavior (homogeneous versus heterogeneous) of the semi-crystalline layers, as probed by differential scanning calorimetry (DSC), provides valuable information on the layered morphology. The use of relatively straightforward DSC measurements shows a clear advantage with respect to the discussed microscopy techniques, since no sample preparation is required and relatively large samples can be studied, which are more representative for the bulk.

Enhancing the antibacterial performance of orthopaedic implant materials by fibre laser surface engineering

Science.gov (United States)

Chan, Chi-Wai; Carson, Louise; Smith, Graham C.; Morelli, Alessio; Lee, Seunghwan

2017-05-01

Implant failure caused by bacterial infection is extremely difficult to treat and usually requires the removal of the infected components. Despite the severe consequence of bacterial infection, research into bacterial infection of orthopaedic implants is still at an early stage compared to the effort on enhancing osseointegration, wear and corrosion resistance of implant materials. In this study, the effects of laser surface treatment on enhancing the antibacterial properties of commercially pure (CP) Ti (Grade 2), Ti6Al4V (Grade 5) and CoCrMo alloy implant materials were studied and compared for the first time. Laser surface treatment was performed by a continuous wave (CW) fibre laser with a near-infrared wavelength of 1064 nm in a nitrogen-containing environment. Staphylococcus aureus, commonly implicated in infection associated with orthopaedic implants, was used to investigate the antibacterial properties of the laser-treated surfaces. The surface roughness and topography of the laser-treated materials were analysed by a 2D roughness testing and by AFM. The surface morphologies before and after 24 h of bacterial cell culture were captured by SEM, and bacterial viability was determined using live/dead staining. Surface chemistry was analysed by XPS and surface wettability was measured using the sessile drop method. The findings of this study indicated that the laser-treated CP Ti and Ti6Al4V surfaces exhibited a noticeable reduction in bacterial adhesion and possessed a bactericidal effect. Such properties were attributable to the combined effects of reduced hydrophobicity, thicker and stable oxide films and presence of laser-induced nano-features. No similar antibacterial effect was observed in the laser-treated CoCrMo.

Effects of 960 nm diode laser irradiation on dental enamel in vitro: temperature and morphological analysis and evaluation of enamel demineralization

International Nuclear Information System (INIS)

Kato, Ilka Tiemy

2004-01-01

The aim of this study is to determine the effects of diode laser irradiation on enamel demineralization. To achieve this goal appropriate photon absorbing substances for the laser radiation, safe laser parameters and adequate temperature measuring apparatus had to be determined. Next, the effects of diode laser and acidulated phosphate fluoride on enamel demineralization by calcium content analysis were evaluated with inductively coupled plasma atomic emission spectrometry (ICP-AES). In the first part of the study, five dyes consisting of vegetable coal diluted in five different liquids were analyzed and vegetable coal diluted in physiological solution was chosen for use as absorber. Methodologies to measure pulp chamber temperature were evaluated and modeling clay was chosen as fixture for the enamel samples held at body temperature. In the second part of the study, different energy density parameters (1.8 J/cm 2 , 3.7 J/cm 2 , 5.6 J/cm 2 , 7.4 J/cm 2 and 9.3 J/cm 2 ) exposure times (10, 15, 20, 25 e 30 seconds) and time intervals between dye application and laser irradiation (5, 30, 60, 90 e 120 seconds) were evaluated with respect to temperature changes in the pulp chamber. The enamel morphology was analyzed by scanning electron microscopy. Acid resistance was measured using seventy five enamel specimens, divided in five groups (control, fluoride, laser, laser + fluoride and fluoride + laser). The amount of calcium lost during demineralization in lactic acid was measured by ICP-AES. The results obtained in this experiment permit the conclusion that diode laser irradiation did not increase acid resistance. When associated with fluoride, the acid resistance did not differ from the results obtained with fluoride alone. (author)

Ao leitor sem medo

Directory of Open Access Journals (Sweden)

José Eisenberg

2000-05-01

Full Text Available O texto resenha Ao leitor sem medo, de Renato Janine Ribeiro (Belo Horizonte, UFMG, 1999.This text is a review of Ao leitor sem medo by Renato Janine Ribeiro (Belo Horizonte, UFMG, 1999

SEM - Morphological evaluation of the root apex in human primary teeth with different degrees of pulpal and periapical pathology

OpenAIRE

Patrícia Motta Fernandes

2007-01-01

O objetivo deste estudo foi avaliar a morfologia da superfície externa de ápices radiculares de dentes decíduos de humanos com necrose pulpar, com e sem lesão periapical visível radiograficamente, e de dentes com vitalidade pulpar, por meio da microscopia eletrônica de varredura (MEV). Dezenove dentes foram extraídos sendo cinco dentes com vitalidade pulpar (Grupo I), seis com necrose pulpar sem lesão periapical (Grupo II) e oito com necrose pulpar e lesão periapical (Grupo III). Os dentes (i...

A new far infrared free-electron laser

CERN Document Server

Walsh, J E; Swartz, J C; Urata, J; Kimmitt, M F

1999-01-01

The operation of a new ultra compact diffraction grating coupled free-electron laser (FEL) has been demonstrated. The basic elements of the device which is termed a grating coupled oscillator (GCO) are the beam in a scanning electron microscope (SEM) and a diffraction grating which is mounted in the e-beam focal region of the SEM. The e-beam is controlled by the SEM's electron optical system and distributed feed back is provided by the grating itself. Recent experimental results are presented and techniques for extending the wavelength and power coverage are discussed.

A new far infrared free-electron laser

International Nuclear Information System (INIS)

Walsh, J.E.; Brownell, J.H.; Swartz, J.C.; Urata, J.; Kimmitt, M.F.

1999-01-01

The operation of a new ultra compact diffraction grating coupled free-electron laser (FEL) has been demonstrated. The basic elements of the device which is termed a grating coupled oscillator (GCO) are the beam in a scanning electron microscope (SEM) and a diffraction grating which is mounted in the e-beam focal region of the SEM. The e-beam is controlled by the SEM's electron optical system and distributed feed back is provided by the grating itself. Recent experimental results are presented and techniques for extending the wavelength and power coverage are discussed

A new far infrared free-electron laser

Energy Technology Data Exchange (ETDEWEB)

Walsh, J.E.; Brownell, J.H.; Swartz, J.C.; Urata, J.; Kimmitt, M.F

1999-06-01

The operation of a new ultra compact diffraction grating coupled free-electron laser (FEL) has been demonstrated. The basic elements of the device which is termed a grating coupled oscillator (GCO) are the beam in a scanning electron microscope (SEM) and a diffraction grating which is mounted in the e-beam focal region of the SEM. The e-beam is controlled by the SEM's electron optical system and distributed feed back is provided by the grating itself. Recent experimental results are presented and techniques for extending the wavelength and power coverage are discussed.

Deposition of matrix-free fullerene films with improved morphology by matrix-assisted pulsed laser evaporation (MAPLE)

DEFF Research Database (Denmark)

Canulescu, Stela; Schou, Jørgen; Fæster, Søren

2013-01-01

Thin films of C60 were deposited by matrix-assisted pulsed laser evaporation (MAPLE) from a frozen target of anisole with 0.67 wt% C60. Above a fluence of 1.5 J/cm2 the C60 films are strongly non-uniform and are resulting from transfer of matrix-droplets containing fullerenes. At low fluence...... the fullerene molecules in the films are intact, the surface morphology is substantially improved and there are no measurable traces of the matrix molecules in the film. This may indicate a regime of dominant evaporation at low fluence which merges into the MAPLE regime of liquid ejection of the host matrix...

Bond strength of an adhesive system irradiated with Nd:YAG laser in dentin treated with Er:YAG laser

International Nuclear Information System (INIS)

Malta, D A M P; De Andrade, M F; Costa, M M; Lizarelli, R F Z; Pelino, J E P

2008-01-01

The purpose of this in vitro study was to verify through micro tensile bond test the bond strength of an adhesive system irradiated with Nd:YAG laser in dentine previously treated with Er:YAG laser. Twenty caries free extracted human third molars were used. The teeth were divided in four experimental groups (n = 5): (G1) control group; (G2) irradiation of the adhesive system with the Nd:YAG laser; (G3) dentin treatment with Er:YAG laser; (G4) dentin treatment with Er:YAG laser followed by the irradiation of the adhesive system with Nd:YAG laser. The Er:YAG laser fluency parameter for the dentin treatment was of 60 J/cm 2 . The adhesive system was irradiated with the Nd:YAG laser with fluency of 100 J/cm 2 . Dental restorations were performed with Adper Single Bond 2/Z250. One tooth from each group was prepared for the evaluation of the adhesive interface under SEM and bond failure tests were also performed and evaluated. The statistical analysis showed statistical significant difference between the groups G1 and G3, G1 and G4, G2 and G3, and G2 and G4; and similarity between the groups G1 and G2, and G3 and G4. The adhesive failures were predominant in all the experimental groups. The SEM analysis showed an adhesive interface with features confirming the results of the mechanical tests. The Nd:YAG laser on the adhesive system did not influence the bond strength in dentin treated or not with the Er:YAG laser

SEM and AFM studies of dip-coated CuO nanofilms.

Science.gov (United States)

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.

A Voxel-Based Method for Automated Identification and Morphological Parameters Estimation of Individual Street Trees from Mobile Laser Scanning Data

Directory of Open Access Journals (Sweden)

Hongxing Liu

2013-01-01

Full Text Available As an important component of urban vegetation, street trees play an important role in maintenance of environmental quality, aesthetic beauty of urban landscape, and social service for inhabitants. Acquiring accurate and up-to-date inventory information for street trees is required for urban horticultural planning, and municipal urban forest management. This paper presents a new Voxel-based Marked Neighborhood Searching (VMNS method for efficiently identifying street trees and deriving their morphological parameters from Mobile Laser Scanning (MLS point cloud data. The VMNS method consists of six technical components: voxelization, calculating values of voxels, searching and marking neighborhoods, extracting potential trees, deriving morphological parameters, and eliminating pole-like objects other than trees. The method is validated and evaluated through two case studies. The evaluation results show that the completeness and correctness of our method for street tree detection are over 98%. The derived morphological parameters, including tree height, crown diameter, diameter at breast height (DBH, and crown base height (CBH, are in a good agreement with the field measurements. Our method provides an effective tool for extracting various morphological parameters for individual street trees from MLS point cloud data.

Characterization of toners and inkjets by laser ablation spectrochemical methods and Scanning Electron Microscopy-Energy Dispersive X-ray Spectroscopy

International Nuclear Information System (INIS)

Trejos, Tatiana; Corzo, Ruthmara; Subedi, Kiran; Almirall, José

2014-01-01

the advantage of being non-destructive to the sample in addition to providing imaging capabilities to further characterize toner samples by their particle morphology. Laser sampling methods resulted in an improvement of the discrimination between different sources with LIBS producing 89% discrimination and LA-ICP-MS resulting in 100% discrimination. In addition, a set of 21 black inkjet samples was examined by each method. The results show that SEM-EDS is not appropriate for inkjet examinations since their elemental composition is typically below the detection capabilities with only sulfur detected in this set, providing only 47.4% discrimination between possible comparison pairs. Laser sampling methods were shown to provide discrimination greater than 94% for this same inkjet set with false exclusion and false inclusion rates lower than 4.1% and 5.7%, for LA-ICP-MS and LIBS respectively. Overall these results confirmed the utility of the examination of printed documents by laser-based micro-spectrochemical methods. SEM-EDS analysis of toners produced a limited utility for discrimination within sources but was not an effective tool for inkjet ink discrimination. Both LA-ICP-MS and LIBS can be used in forensic laboratories to chemically characterize inks on documents and to complement the information obtained by conventional methods and enhance their evidential value. - Highlights: • We describe the analysis of printer inks on paper using LA-ICP-MS, LIBS and SEM-EDS. • Analytical figures of merit and the relative discrimination power for each technique is described. • Both LA-ICP-MS and LIBS provide excellent discrimination between different printer sources

Characterization of toners and inkjets by laser ablation spectrochemical methods and Scanning Electron Microscopy-Energy Dispersive X-ray Spectroscopy

Energy Technology Data Exchange (ETDEWEB)

Trejos, Tatiana, E-mail: trejost@fiu.edu; Corzo, Ruthmara, E-mail: rcorz001@fiu.edu; Subedi, Kiran, E-mail: ksube001@fiu.edu; Almirall, José, E-mail: almirall@fiu.edu

2014-02-01

the advantage of being non-destructive to the sample in addition to providing imaging capabilities to further characterize toner samples by their particle morphology. Laser sampling methods resulted in an improvement of the discrimination between different sources with LIBS producing 89% discrimination and LA-ICP-MS resulting in 100% discrimination. In addition, a set of 21 black inkjet samples was examined by each method. The results show that SEM-EDS is not appropriate for inkjet examinations since their elemental composition is typically below the detection capabilities with only sulfur detected in this set, providing only 47.4% discrimination between possible comparison pairs. Laser sampling methods were shown to provide discrimination greater than 94% for this same inkjet set with false exclusion and false inclusion rates lower than 4.1% and 5.7%, for LA-ICP-MS and LIBS respectively. Overall these results confirmed the utility of the examination of printed documents by laser-based micro-spectrochemical methods. SEM-EDS analysis of toners produced a limited utility for discrimination within sources but was not an effective tool for inkjet ink discrimination. Both LA-ICP-MS and LIBS can be used in forensic laboratories to chemically characterize inks on documents and to complement the information obtained by conventional methods and enhance their evidential value. - Highlights: • We describe the analysis of printer inks on paper using LA-ICP-MS, LIBS and SEM-EDS. • Analytical figures of merit and the relative discrimination power for each technique is described. • Both LA-ICP-MS and LIBS provide excellent discrimination between different printer sources.

[Effects of laser welding on bond of porcelain fused cast pure titanium].

Science.gov (United States)

Zhu, Juan-fang; He, Hui-ming; Gao, Bo; Wang, Zhong-yi

2006-04-01

To investigate the influence of the laser welding on bond of porcelain fused to cast pure titanium. Twenty cast titanium plates were divided into two groups: laser welded group and control group. The low-fusing porcelain was fused to the laser welded cast pure titanium plates at fusion zone. The bond strength of the porcelain to laser welded cast pure titanium was measured by the three-point bending test. The interface of titanium and porcelain was investigated by scanning electron microscopy (SEM) and energy depressive X-ray detector (EDX). The non-welded titanium plates were used as comparison. No significant difference of the bond strength was found between laser-welded samples [(46.85 +/- 0.76) MPa] and the controls [(41.71 +/- 0.55) MPa] (P > 0.05). The SEM displayed the interface presented similar irregularities with a predominance. The titanium diffused to low-fusing porcelain, while silicon and aluminum diffused to titanium basement. Laser welding does not affect low-fusing porcelain fused to pure titanium.

Structural and morphological characterizations of ZnO films grown on GaAs substrates by MOCVD

Energy Technology Data Exchange (ETDEWEB)

Agouram, S.; Zuniga Perez, J.; Munoz-Sanjose, V. [Universitat de Valencia, Departamento de Fisica Aplicada y Electromagnetismo, Burjassot (Spain)

2007-07-15

ZnO films were grown on GaAs(100), GaAs(111)A and GaAs(111)B substrates by metal organic chemical vapour deposition (MOCVD). Diethylzinc (DEZn) and tertiarybutanol (t-butanol) were used as Zn and O precursors, respectively. The influence of the growth temperature and GaAs substrate orientation on the crystalline orientation and morphology of the ZnO grown films has been analysed. Crystallinity of grown films was studied by X-ray diffraction (XRD); thickness and morphology of ZnO films were investigated by scanning electron microscopy (SEM). SEM results reveal significant differences between morphologies depending on growth temperature but not significant differences were detected on the texture of grown films. (orig.)

Effect of dry and wet ambient environment on the pulsed laser ablation of titanium

International Nuclear Information System (INIS)

Ali, Nisar; Bashir, Shazia; Umm-i-Kalsoom,; Akram, Mahreen; Mahmood, Khaliq

2013-01-01

Surface and structural properties of the laser irradiated titanium targets have been investigated under dry and wet ambient environments. For this purpose KrF Excimer laser of wavelength 248 nm, pulse duration of 20 ns and repetition rate of 20 Hz has been employed. The targets were exposed for various number of laser pulses ranging from 500 to 2000 in the ambient environment of air, de-ionized water and propanol at a fluence of 3.6 J/cm 2 . The surface morphology, chemical composition and crystallographical analysis were performed by using Scanning Electron Microscope (SEM), Energy Dispersive X-ray Spectroscopy (EDS) and X-ray Diffraction (XRD), respectively. For both central and peripheral ablated areas, significant difference in surface morphology has been observed in case of dry and wet ambient conditions. Large sized and diffused grains are observed in case of dry ablation. Whereas, in case of wet ablation, small sized, and well defined grains with distinct grain boundaries and significantly enhanced density are revealed. This difference is ascribed to the confinement effects of the liquid. The peripheral ablated area shows redeposition in case of dry ablation whereas small sized grain like structures are formed in case of wet ablation. EDS analysis exhibits variation in chemical composition under both ambient conditions. When the targets are treated in air environment, enhancement of the oxygen as well as nitrogen content is observed while in case of de-ionized water and propanol only increase in content of oxygen is observed. X-ray diffraction analysis exhibits formation of oxides and nitrides in case of air, whereas, in case of de-ionized water and propanol only oxides along with hydrides are formed. For various number of laser pulses the variation in the peak intensity, crystallinity and d-spacing is observed under both ambient conditions.

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

Science.gov (United States)

Drobne, Damjana

2013-01-01

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

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

Science.gov (United States)

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

2007-01-01

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

Nanosecond pulsed laser ablation of brass in a dry and liquid-confined environment

Science.gov (United States)

Bashir, Shazia; Vaheed, Hamza; Mahmood, Khaliq

2013-02-01

The effect of ambient environment (dry or wet) and overlapping laser pulses on the laser ablation performance of brass has been investigated. For this purpose, a Q-switched, frequency doubled Nd:YAG laser with a wavelength of 532 nm, pulse energy of 150 mJ, pulse width of 6 ns and repetition rate of 10 Hz is employed. In order to explore the effect of ambient environments, brass targets have been exposed in deionized water, methanol and air. The targets are exposed for 1000, 2000, 3000 and 4000 succeeding pulses in each atmosphere. The surface morphology and chemical composition of ablated targets have been characterized by using Scanning Electron Microscope (SEM), Atomic Force Microscope (AFM) and Attenuated Total Reflection (ATR) techniques. In case of liquid environment, various features like nano- and micro-scale laser-induced periodic surface structures with periodicity 500 nm-1 μm, cavities of size few micrometers with multiple ablative layers and phenomenon of thermal stress cracking are observed. These features are originated by various chemical and thermal phenomena induced by laser heating at the liquid-solid interfaces. The convective bubble motion, explosive boiling, pressure gradients, cluster and colloid formation due to confinement effects of liquids are possible cause for such kind of features. The metal oxides and alcohol formed on irradiated surface are also playing the significant role for the formation of these kinds of structure. In case of air one huge crater is formed along with the redeposition of sputtered material and is ascribed to laser-induced evaporation and oxide formation.

Morphology and crystallinity of sisal nanocellulose after sonication

Science.gov (United States)

Sosiati, H.; Wijayanti, D. A.; Triyana, K.; Kamiel, B.

2017-09-01

Different preparation methods on the natural fibers resulted in different morphology. However, the relationships between type of natural fibers, preparation methods and the morphology of produced nanocellulose could not be exactly defined. The sisal nanocellulose was presently prepared by alkalization and bleaching followed by sonication to verify changes in the morphology and crystallinity of nanocellulose related to the formation mechanism. The extracted microcellulose was subjected to scanning electron microscopy (SEM) and x-ray diffraction (XRD) analysis. The isolated cellulose nanospheres were examined with respect to morphology by SEM and transmission electron microscopy (TEM) and, to crystallinity by electron diffraction analysis. Bleaching after alkalization made the microfibrils clearly separated from each other to the individual fiber whose width of the single fiber was ranging from 6 to 13 µm. The XRD crystallinity index (CI) of microcellulose gradually increased after the chemical treatments; 83.12% for raw sisal fiber, 88.57% for alkali treated fiber and 94.03% for bleached fibers. The ultrasonic agitation after bleaching that was carried out at 750 Watt, 20 kHz and amplitude of 39% for 2 h produces homogeneous cellulose nanospheres less than 50 nm in diameter with relatively low crystallinity. The electron diffraction analysis confirmed that the low crystallinity of produced nnocellulose is related to the effect of chemical treatment done before sonication.

Morphological and Production Changes in Planktonic and Biofilm Cells Monitored Using SEM and Raman Spectroscopy

Czech Academy of Sciences Publication Activity Database

Hrubanová, Kamila; Krzyžánek, Vladislav; Samek, Ota; Skoupý, Radim; Šiler, Martin; Ježek, Jan; Obruča, S.; Zemánek, Pavel

2017-01-01

Roč. 23, S1 (2017), s. 1158-1159 ISSN 1431-9276 R&D Projects: GA ČR(CZ) GA15-20645S; GA ČR(CZ) GA16-12477S; GA ČR(CZ) GA17-15451S; GA MŠk(CZ) LO1212; GA MŠk ED0017/01/01 Institutional support: RVO:68081731 Keywords : biofilm cells * SEM * Raman spectroscopy Subject RIV: JA - Electronics ; Optoelectronics, Electrical Engineering OBOR OECD: Electrical and electronic engineering Impact factor: 1.891, year: 2016

Crystallization of 21.25Gd2O3-63.75MoO3-15B2O3 glass induced by femtosecond laser at the repetition rate of 250 kHz

International Nuclear Information System (INIS)

Zhong, M.J.; Han, Y.M.; Liu, L.P.; Zhou, P.; Du, Y.Y.; Guo, Q.T.; Ma, H.L.; Dai, Y.

2010-01-01

We report the formation of β'-Gd 2 (MoO 4 ) 3 (GMO) crystal on the surface of the 21.25Gd 2 O 3 -63.75MoO 3 -15B 2 O 3 glass, induced by 250 kHz, 800 nm femtosecond laser irradiation. The morphology of the modified region in the glass was clearly examined by scanning electron microscopy (SEM). By micro-Raman spectra, the laser-induced crystals were confirmed to be GMO phases and it is found that these crystals have a strong dependence on the number and power of the femtosecond laser pulses. When the irradiation laser power was 900 mW, not only the Raman peaks of GMO crystals but also some new peaks at 214 cm -1 , 240 cm -1 , 466 cm -1 , 664 cm -1 and 994 cm -1 which belong to the MoO 3 crystals were observed. The possible mechanisms are proposed to explain these phenomena.

Cypris morphology in the barnacles Ibla and Paralepas (Crustacea: Cirripedia Thoracica) implications for cirripede evolution

DEFF Research Database (Denmark)

Høeg, Jens T; Achituv, Yair; Chan, Benny K K

2009-01-01

We used scanning electron microscopy (SEM) to describe cypris morphology in species of the barnacles Ibla and Paralepas, both of which are pivotal in understanding cirripede evolution. In Ibla, we also studied late naupliar stages with video and SEM. Special emphasis was put on the lattice organs...

Elaboration of submicron structures on PEEK polymer by femtosecond laser

International Nuclear Information System (INIS)

Hammouti, S.; Beaugiraud, B.; Salvia, M.; Mauclair, C.; Pascale-Hamri, A.; Benayoun, S.; Valette, S.

2015-01-01

Highlights: • We compare PEEK polymer under two crystalline forms: semi-crystalline and amorphous. • We assess topographical modifications of surface morphologies after femtosecond laser irradiation. • At low laser energy regime, there is an influence of the crystallinity rate on topographical features of surface morphologies. • At high laser energy regime, the contribution of the crystallinity tends to disappear. - Abstract: In this work, laser parameters initiating the emergence of periodic structures, so-called ripples on poly (ether ether ketone) (PEEK) surfaces, are investigated. PEEK was used in its semi-crystalline and amorphous forms. Polymer surfaces were treated locally by performing a matrix of laser impacts to highlight the influence of the crystallinity in ultrashort laser interaction. Different surface morphologies or ripples were analyzed by atomic force microscopy and optical interferometry. A map of the presence of these different morphologies according to the laser fluence and the number of pulses was established. Analysis by optical interferometry was carried out and led to the calculations of ablation efficiency. Some significant differences were demonstrated between amorphous and semi-crystalline surfaces. This work revealed topographical information on the local behavior of the irradiated material. Finally, the crystallinity rate of polymer surface seems to be a determinant factor for the periodic nanostructured appearance

Elaboration of submicron structures on PEEK polymer by femtosecond laser

Energy Technology Data Exchange (ETDEWEB)

Hammouti, S., E-mail: sabrina.hammouti@ec-lyon.fr [LTDS, Ecole Centrale de Lyon, 36 Avenue Guy de Collongue, 69134 Ecully (France); Beaugiraud, B.; Salvia, M. [LTDS, Ecole Centrale de Lyon, 36 Avenue Guy de Collongue, 69134 Ecully (France); Mauclair, C. [LaHC, Université Jean Monnet, 18 rue du Professeur Benoît Lauras, 42000 Saint-Etienne (France); MANUTECH-USD, 20 rue du Professeur Benoît Lauras, 42000 Saint-Etienne (France); Pascale-Hamri, A. [MANUTECH-USD, 20 rue du Professeur Benoît Lauras, 42000 Saint-Etienne (France); Benayoun, S. [LTDS, Ecole Centrale de Lyon, 36 Avenue Guy de Collongue, 69134 Ecully (France); Valette, S. [LTDS, Ecole Centrale de Lyon, 36 Avenue Guy de Collongue, 69134 Ecully (France); MANUTECH-USD, 20 rue du Professeur Benoît Lauras, 42000 Saint-Etienne (France)

2015-02-01

Highlights: • We compare PEEK polymer under two crystalline forms: semi-crystalline and amorphous. • We assess topographical modifications of surface morphologies after femtosecond laser irradiation. • At low laser energy regime, there is an influence of the crystallinity rate on topographical features of surface morphologies. • At high laser energy regime, the contribution of the crystallinity tends to disappear. - Abstract: In this work, laser parameters initiating the emergence of periodic structures, so-called ripples on poly (ether ether ketone) (PEEK) surfaces, are investigated. PEEK was used in its semi-crystalline and amorphous forms. Polymer surfaces were treated locally by performing a matrix of laser impacts to highlight the influence of the crystallinity in ultrashort laser interaction. Different surface morphologies or ripples were analyzed by atomic force microscopy and optical interferometry. A map of the presence of these different morphologies according to the laser fluence and the number of pulses was established. Analysis by optical interferometry was carried out and led to the calculations of ablation efficiency. Some significant differences were demonstrated between amorphous and semi-crystalline surfaces. This work revealed topographical information on the local behavior of the irradiated material. Finally, the crystallinity rate of polymer surface seems to be a determinant factor for the periodic nanostructured appearance.

Search Engine Marketing (SEM): Financial & Competitive Advantages of an Effective Hotel SEM Strategy

OpenAIRE

Leora Halpern Lanz

2015-01-01

Search Engine Marketing and Optimization (SEO, SEM) are keystones of a hotels marketing strategy, in fact research shows that 90% of travelers start their vacation planning with a Google search. Learn five strategies that can enhance a hotels SEO and SEM strategies to boost bookings.

Growth behavior of laser-induced damage on fused silica optics under UV, ns laser irradiation.

Science.gov (United States)

Negres, Raluca A; Norton, Mary A; Cross, David A; Carr, Christopher W

2010-09-13

The growth behavior of laser-induced damage sites is affected by a large number of laser parameters as well as site morphology. Here we investigate the effects of pulse duration on the growth rate of damage sites located on the exit surface of fused silica optics. Results demonstrate a significant dependence of the growth parameters on laser pulse duration at 351 nm from 1 ns to 15 ns, including the observation of a dominant exponential versus linear, multiple-shot growth behavior for long and short pulses, respectively. These salient behaviors are tied to the damage morphology and suggest a shift in the fundamental growth mechanisms for pulses in the 1-5 ns range.

Larval morphology of Chrysomya nigripes (Diptera: Calliphoridae), a fly species of forensic importance.

Science.gov (United States)

Sukontason, Kabkaew L; Vogtsberger, Roy C; Boonchu, Noppawan; Chaiwong, Tarinee; Sripakdee, Duanghatai; Ngern-Klun, Radchadawan; Piangjai, Somsak; Sukontason, Kom

2005-05-01

The morphology of all instars of Chrysomya nigripes Aubertin, a blow fly species of forensic importance, is presented with the aid of both light microscopy and scanning electron microscopy (SEM). Morphological features of the cephalopharyngeal skeleton, anterior spiracle, posterior spiracle, and dorsal spines between the prothorax and mesothorax are highlighted. No consistent features were found, even using SEM, for distinguishing the first instar of C. nigripes from that of Chrysomya megacephala (F.) or Chrysomya rufifacies (Macquart), two other commonly associated blow fly species in corpses in Thailand. Several features observed in second and third instars proved to be valuable characteristics for separating these species.

SEM investigation of incandescent lamp mantle structure on durability

International Nuclear Information System (INIS)

Gerneke, D.; Lang, C.

2002-01-01

Full text: The incandescent mantle as used on pressure and non-pressure liquid fuel lamps has been in use for over 100 years. What remains unexplained is the way in which the resistance to mechanical shock and the decline in tensile strength with usage is experienced. It has been suggested that to improve durability it is necessary to continuously burn a new mantle for the first two to three hours. The known factors in mantle durability and mechanical strength are chemical composition and fabric weave. This study was undertaken to investigate the effects of burning time and temperature on thorium oxide mantles. The operating temperature of mantles on a range of kerosene pressure lamps was measured and found to be between 800 and 1100 deg C. Heat treatments of thorium based Coleman mantles were carried out in a laboratory furnace within these ranges of temperatures for periods ranging from 2 minutes to 2 hours. The mantles were then viewed in a LEO S440 analytical SEM. Results at 800 deg C show a distinct change in surface morphology with increasing exposure time. At the shorter times (2-5 minutes) the surface was relatively smooth. With increased time periods (15 - 120 minutes) the surface was observed to have a large lumpy structure. At 1100 deg C the difference in surface morphology was not apparent between the shortest and longest times. The surface appears much smoother and no lumpy structure was observed. This suggests that when a mantle is operated at the higher temperature of 1100 deg C the structure of the Thorium oxide is quickly transformed into the known stronger amorphous form. This is taken as the observed smooth structure seen in the SEM images of the 1100 deg C samples. Thus the mantle is expected to be more resistant to mechanical shock and have increased durability. Practical field test results confirm these observations. The mantle on a lamp that is operating efficiently, burns brightly, will far outlast a mantle on an inefficient lamp which bums

Analysis of Boling's laser-damage morphology

International Nuclear Information System (INIS)

Sparks, M.S.

1980-01-01

Boling observed that his total-internal-reflection laser-damage sites in glass closely resembled the scattering cross section for small (ka << 1), perfectly conducting sphere and suggested that a very small plasma formed and grew to a larger size, still with ka << 1 satisfied. Even with ka = 1, for which the cross section is different from that observed, the scattered field still is too small to explain the damage in terms of constructive interference between the incident- and scattered fields. Furthermore, the characteristic shape of the scattering cross section that matches the damage patterns is for circular polarization or unpolarized light, in contrast to the experimental plane polarizations. Extending the ideas to include effects of the scattered field outside the glass, such as plasma formation, and to include the correct field (with interesting polarization, including longitudinal circuler polarization at certain distances from the surface) incident on the sphere may explain the experiments. Additional experiments and analysis would be useful to determine if the extended model is valid and to investigate related materials improvement, nondestructive testing, and the relation between laser damage, plasma initiation, and failure under stress, all initiated at small isolated spots

Processing of pure Ti by rapid prototyping based on laser cladding

Science.gov (United States)

Arias-González, F.; del Val, J.; Comesaña, R.; Lusquiños, F.; Quintero, F.; Riveiro, A.; Boutinguiza, M.; Pou, J.

2013-11-01

Rapid prototyping based on laser cladding is an additive manufacturing (AM) process based on the overlapping of cladding tracks to produce functional components. Powder or wire are fed into a melting pool created using laser radiation as a heat source and the relative movement between the beam and the work piece makes possible to generate pieces layer-by-layer. This technique can be applied for any material which can be melted and the components can be manufactured directly according to a computer aided design (CAD) model. Additive manufacturing is particularly interesting to produce titanium components because, in this case, the loss of material produced by subtractive manufacturing methods is highly costly. Moreover, titanium and its alloys are widely used in biomedical, aircraft, chemical and marine industries due to their biocompatibility, excellent corrosion resistance and superior strength-to-weight ratio. In this research work, a near-infrared laser delivering a maximum power of 500W is used to produce pure titanium thin parts. Dimensions and surface morphology are characterized using Optical Microscopy (OM) and Scanning Electron Microscopy (SEM), the hardness by nanoindentation and the composition by X-Ray Diffraction (XRD) and Energy Dispersive X-Ray Spectroscopy (EDS). The aim of this work is to establish the conditions under which satisfactory properties are obtained and to understand the relationship between microstructure/properties and deposition parameters.

Search Engine Marketing (SEM: Financial & Competitive Advantages of an Effective Hotel SEM Strategy

Directory of Open Access Journals (Sweden)

Leora Halpern Lanz

2015-05-01

Full Text Available Search Engine Marketing and Optimization (SEO, SEM are keystones of a hotels marketing strategy, in fact research shows that 90% of travelers start their vacation planning with a Google search. Learn five strategies that can enhance a hotels SEO and SEM strategies to boost bookings.

Effects of milling method and calcination condition on phase and morphology characteristics of Mg4Nb2O9 powders

International Nuclear Information System (INIS)

Wongmaneerung, R.; Sarakonsri, T.; Yimnirun, R.; Ananta, S.

2006-01-01

Magnesium niobate, Mg 4 Nb 2 O 9 , powders has been synthesized by a solid-state reaction. Both conventional ball- and rapid vibro-milling have been investigated as milling methods, with the formation of the Mg 4 Nb 2 O 9 phase investigated as a function of calcination conditions by DTA and XRD. The particle size distribution of the calcined powders was determined by laser diffraction technique, while morphology, crystal structure and phase composition were determined via a combination of SEM, TEM and EDX techniques. The type of milling method together with the designed calcination condition was found to show a considerable effect on the phase and morphology evolution of the calcined Mg 4 Nb 2 O 9 powders. It is seen that optimization of calcination conditions can lead to a single-phase Mg 4 Nb 2 O 9 in both milling methods. However, the formation temperature and dwell time for single-phase Mg 4 Nb 2 O 9 powders were lower with the rapid vibro-milling technique

Variations in fixation techniques for field emission SEM and TEM of zebrafish (Branchydanio rerio) embryo inner and outer membranes

NARCIS (Netherlands)

Kalicharan, D; Jongebloed, WL; Rawson, DM; Zhang, TT

1998-01-01

The morphology of embryos of the fresh water teleost, Brachydania rerio (zebrafish), was examined in a parallel FE-SEM/TEM study, after various pre- and post-fixation regimes. Special attention was paid to the chorion, the contents of the peri-vitelline space, the plasma membrane, the syncytial

Morphology study of niobium pentoxide

International Nuclear Information System (INIS)

Romero, R.P.P.; Panta, P.C.; Araujo, A.O. de; Bergmann, C.P.

2016-01-01

Currently, Niobium pentoxide (Nb 2 O 5 ) has been studied due to physical properties and their use in obtaining electronic ceramics, optical lenses, pH sensors, special filters for TV receivers, among other applications. This study investigated the morphology of the niobium pentoxide obtained by hydrothermal synthesis from the precursor pentachloride niobium (NbCl 5 ), where the synthesis was carried out at a temperature of 150 and 200 °C for 130 min and the product obtained was calcined at temperatures 600, 800 and 1000 °C for 60 min. The following characterizations were performed for analysis of the material, among them, X-ray diffraction (XRD) for analysis of the crystal structure, thermal gravimetric analysis (TGA) for detecting the existing functional groups and scanning electron microscopy (SEM) for morphology of material. As a result, different morphologies were obtained and consequently different niobium pentoxide properties studied. (author)

3D reconstruction of SEM images by use of optical photogrammetry software.

Science.gov (United States)

Eulitz, Mona; Reiss, Gebhard

2015-08-01

Reconstruction of the three-dimensional (3D) surface of an object to be examined is widely used for structure analysis in science and many biological questions require information about their true 3D structure. For Scanning Electron Microscopy (SEM) there has been no efficient non-destructive solution for reconstruction of the surface morphology to date. The well-known method of recording stereo pair images generates a 3D stereoscope reconstruction of a section, but not of the complete sample surface. We present a simple and non-destructive method of 3D surface reconstruction from SEM samples based on the principles of optical close range photogrammetry. In optical close range photogrammetry a series of overlapping photos is used to generate a 3D model of the surface of an object. We adapted this method to the special SEM requirements. Instead of moving a detector around the object, the object itself was rotated. A series of overlapping photos was stitched and converted into a 3D model using the software commonly used for optical photogrammetry. A rabbit kidney glomerulus was used to demonstrate the workflow of this adaption. The reconstruction produced a realistic and high-resolution 3D mesh model of the glomerular surface. The study showed that SEM micrographs are suitable for 3D reconstruction by optical photogrammetry. This new approach is a simple and useful method of 3D surface reconstruction and suitable for various applications in research and teaching. Copyright © 2015 Elsevier Inc. All rights reserved.

Topography induced by sputtering in a magnetic sector instrument: an AFM and SEM study

International Nuclear Information System (INIS)

Iacob, E.; Bersani, M.; Lui, A.; Giubertoni, D.; Barozzi, M.; Anderle, M.

2004-01-01

Due to the sensitivity, the good depth resolution and the great interest in ultra shallow profile, secondary ion mass spectrometry (SIMS) is one of the prime techniques used in the semiconductor industry. Low impact energy beams are required to profile shallow distributions. Since Cs + beam sputtering can cause morphological artifacts as well as O 2 + beam does, a detailed study is required to understand development and limiting analytical conditions. In this work we analyzed the effect of low energy Cs + primary beam incident at 68 deg. and 78 deg. on different silicon samples. By using atomic force microscopy (AFM) and scanning electron microscopy (SEM) we underline their reliability and correlate the morphological effects to the SIMS analytical parameters and samples characteristics

Spin-polarized SEM

International Nuclear Information System (INIS)

Konoto, Makoto

2007-01-01

Development of highly effective evaluation technology of magnetic structures on a nanometric scale is a key to understanding spintronics and related phenomena. A high-resolution spin-polarized scanning electron microscope (spin SEM) developed recently is quite suitable for probing such nanostructures because of the capability of analyzing local magnetization vectors in three dimensions. Utilizing the spin SEM, a layered antiferromagnetic structure with the 1nm-alternation of bilayer-sheet magnetization has been successfully resolved. The real-space imaging with full analysis of the temperature-dependent magnetization vectors will be demonstrated. (author)

Bioactivity of calcium phosphate bioceramic coating fabricated by laser cladding

Science.gov (United States)

Zhu, Yizhi; Liu, Qibin; Xu, Peng; Li, Long; Jiang, Haibing; Bai, Yang

2016-05-01

There were always strong expectations for suitable biomaterials used for bone regeneration. In this study, to improve the biocompatiblity of titanium alloy, calcium phosphate bioceramic coating was obtained by laser cladding technology. The microstructure, phases, bioactivity, cell differentiation, morphology and resorption lacunae were investigated by optical microscope (OM), x-ray diffraction (XRD), methyl thiazolyl tetrazolium (MTT) assay, tartrate-resistant acid phosphatase (TRAP) staining and scanning electronic microscope (SEM), respectively. The results show that bioceramic coating consists of three layers, which are a substrate, an alloyed layer and a ceramic layer. Bioactive phases of β-tricalcium phosphate (β-TCP) and hydroxyapatite (HA) were found in ceramic coating. Osteoclast precursors have excellent proliferation on the bioceramic surface. The bioceramics coating could be digested by osteoclasts, which led to the resorption lacunae formed on its surface. It revealed that the gradient bioceramic coating has an excellent bioactivity.

Bioactivity of calcium phosphate bioceramic coating fabricated by laser cladding

International Nuclear Information System (INIS)

Zhu, Yizhi; Liu, Qibin; Xu, Peng; Li, Long; Jiang, Haibing; Bai, Yang

2016-01-01

There were always strong expectations for suitable biomaterials used for bone regeneration. In this study, to improve the biocompatiblity of titanium alloy, calcium phosphate bioceramic coating was obtained by laser cladding technology. The microstructure, phases, bioactivity, cell differentiation, morphology and resorption lacunae were investigated by optical microscope (OM), x-ray diffraction (XRD), methyl thiazolyl tetrazolium (MTT) assay, tartrate-resistant acid phosphatase (TRAP) staining and scanning electronic microscope (SEM), respectively. The results show that bioceramic coating consists of three layers, which are a substrate, an alloyed layer and a ceramic layer. Bioactive phases of β-tricalcium phosphate (β-TCP) and hydroxyapatite (HA) were found in ceramic coating. Osteoclast precursors have excellent proliferation on the bioceramic surface. The bioceramics coating could be digested by osteoclasts, which led to the resorption lacunae formed on its surface. It revealed that the gradient bioceramic coating has an excellent bioactivity. (letter)

Dross formation during laser cutting process

Energy Technology Data Exchange (ETDEWEB)

Yilbas, B S; Aleem, B J Abdul [Mechanical Engineering Department, King Fahd University of Petoleum and Minerals, Dhahran 32161 (Saudi Arabia)

2006-04-07

Melt formation during laser cutting of metallic substrates is considered and the melt thickness is formulated using a lump parameter analysis. The droplet diameter is also predicted and compared with the experimental results. A CO{sub 2} laser with variable pulse frequency is used in the experiment. Oxygen, as assisting gas, impinging coaxially with the laser beam, is used at different pressures. SEM and XRD are carried out to obtain micrographs and oxide compounds formed in the dross. It is found that the liquid layer thickness increases with increasing laser output power and reduces with increasing assisting gas velocity. The droplet formed is spherical and the droplet size predicted agrees well with the experimental results.

Structural and morphological characterization of fullerite crystals prepared from the vapor phase

International Nuclear Information System (INIS)

Haluska, M.; Fejdi, P.; Vybornov, M.; Kuzmany, H.

1993-01-01

Crystal structure, habits and surface structures of fullerite crystals prepared from vapor phase were characterized by X-ray analysis, interfacial angle measurements and optical and scanning electron microscopy (SEM). The study of selected C 60 crystals confirmed the fcc structure at room temperature. The crystal habit is determined by two types of morphological faces, namely {100} and {111}. SEM was used for the observation of thermal etched surfaces. (orig.)

Dynamics of laser speckle imaging of blood flow and morphological changes in tissues with a full time local ischemia of pancreas

Directory of Open Access Journals (Sweden)

Alexandrov D.A.

2014-12-01

Full Text Available The purpose: to establish influence of a full ischemia of different duration and the subsequent reperfusionon pathology development in pancreas of rats by means of laser speckle-visualization and lifetime digital microscopy. Materials and Methods. The work has been performed on 42 white rats of line Wistar in weight of 200-250 Research of properties of a blood-groove was made by means of methods laser Doppler flowmetry, digital biomicroscopy and a method of laser speckle-contrast visualization. Results. After the termination of a 5-minute full ischemia the speed of bloodflow has been increased in 2-3 times, clinic pancreatic necrosis is marked does not develop. After the termination of 20-minute full ischemia the increase in speed of a bloodflow did not occur, there were morphological and clinical signs of pancreatic necrosis. Conclusion, the efficiency of monitoring of microhemodynamics of pancreas in rats by the method of speckle-capillary of full field has been shown. Multidirectional phase of perfusion changes in pancreas have been revealed after reversible infringement of blood supply of different duration.

Production of zinc oxide nanowires power with precisely defined morphology

Science.gov (United States)

Mičová, Júlia; Remeš, Zdeněk; Chan, Yu-Ying

2017-12-01

The interest about zinc oxide is increasing thanks to its unique chemical and physical properties. Our attention has focused on preparation powder of 1D nanostructures of ZnO nanowires with precisely defined morphology include characterization size (length and diameter) and shape controlled in the scanning electron microscopy (SEM). We have compared results of SEM with dynamic light scattering (DLS) technique. We have found out that SEM method gives more accurate results. We have proposed transformation process from ZnO nanowires on substrates to ZnO nanowires powder by ultrasound peeling to colloid followed by lyophilization. This method of the mass production of the ZnO nanowires powder has some advantages: simplicity, cost effective, large-scale and environment friendly.

Analysis list: sem-4 [Chip-atlas[Archive

Lifescience Database Archive (English)

Full Text Available sem-4 Larvae + ce10 http://dbarchive.biosciencedbc.jp/kyushu-u/ce10/target/sem-4.1....tsv http://dbarchive.biosciencedbc.jp/kyushu-u/ce10/target/sem-4.5.tsv http://dbarchive.biosciencedbc.jp/kyushu-u/ce10/target/sem...-4.10.tsv http://dbarchive.biosciencedbc.jp/kyushu-u/ce10/colo/sem-4.Larvae.tsv http://dbarchive.biosciencedbc.jp/kyushu-u/ce10/colo/Larvae.gml ...

Influence of deposition temperature on the structural and morphological properties of Be3N2 thin films grown by reactive laser ablation

International Nuclear Information System (INIS)

Chale-Lara, F.; Farias, M.H.; De la Cruz, W.; Zapata-Torres, M.

2010-01-01

Be 3 N 2 thin films have been grown on Si(1 1 1) substrates using the pulsed laser deposition method at different substrate temperatures: room temperature (RT), 200 deg. C, 400 deg. C, 600 deg. C and 700 deg. C. Additionally, two samples were deposited at RT and were annealed after deposition in situ at 600 deg. C and 700 deg. C. In order to obtain the stoichiometry of the samples, they have been characterized in situ by X-ray photoelectron (XPS) and reflection electron energy loss spectroscopy (REELS). The influence of the substrate temperature on the morphological and structural properties of the films was investigated using scanning electron microscopy (SEM), atomic force microscopy (AFM) and X-ray diffraction (XRD). The results show that all prepared films presented the Be 3 N 2 stoichiometry. Formation of whiskers with diameters of 100-200 nm appears at the surface of the films prepared with a substrate temperature of 600 deg. C or 700 deg. C. However, the samples grown at RT and annealed at 600 deg. C or 700 deg. C do not show whiskers on the surface. The average root mean square (RMS) roughness and the average grain size of the samples grown with respect the substrate temperature is presented. The films grown with a substrate temperature between the room temperature to 400 deg. C, and the sample annealed in situ at 600 deg. C were amorphous; while the αBe 3 N 2 phase was presented on the samples with a substrate temperature of 600 deg. C, 700 deg. C and that deposited with the substrate at RT and annealed in situ at 700 deg. C.

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

Science.gov (United States)

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.

Laser induced local structural and property modifications in semiconductors for electronic and photonic superstructures - Silicon carbide to graphene conversion

Science.gov (United States)

Yue, Naili

Graphene is a single atomic layer two-dimensional (2D) hexagonal crystal of carbon atoms with sp2-bonding. Because of its various special or unique properties, graphene has attracted huge attention and considerable interest in recent years. This PhD research work focuses on the development of a novel approach to fabricating graphene micro- and nano-structures using a 532 nm Nd:YAG laser, a technique based on local conversion of 3C-SiC thin film into graphene. Different from other reported laser-induced graphene on single crystalline 4H- or 6H- SiC, this study focus on 3C-SiC polycrystal film grown using MBE. Because the SiC thin film is grown on silicon wafer, this approach may potentially lead to various new technologies that are compatible with those of Si microelectronics for fabricating graphene-based electronic, optoelectronic, and photonic devices. The growth conditions for depositing 3C-SiC using MBE on Si wafers with three orientations, (100), (110), and (111), were evaluated and explored. The surface morphology and crystalline structure of 3C-SiC epilayer were investigated with SEM, AFM, XRD, μ-Raman, and TEM. The laser modification process to convert 3C-SiC into graphene layers has been developed and optimized by studying the quality dependence of the graphene layers on incident power, irradiation time, and surface morphology of the SiC film. The laser and power density used in this study which focused on thin film SiC was compared with those used in other related research works which focused on bulk SiC. The laser-induced graphene was characterized with μ-Raman, SEM/EDS, TEM, AFM, and, I-V curve tracer. Selective deposition of 3C-SiC thin film on patterned Si substrate with SiO2 as deposition mask has been demonstrated, which may allow the realization of graphene nanostructures (e.g., dots and ribbons) smaller than the diffraction limit spot size of the laser beam, down to the order of 100 nm. The electrical conductance of directly written graphene

Pulsed Laser Annealing of Thin Films of Self-Assembled Nanocrystals

KAUST Repository

Baumgardner, William J.

2011-09-27

We investigated how pulsed laser annealing can be applied to process thin films of colloidal nanocrystals (NCs) into interconnected nanostructures. We illustrate the relationship between incident laser fluence and changes in morphology of PbSe NC films relative to bulk-like PbSe films. We found that laser pulse fluences in the range of 30 to 200 mJ/cm2 create a processing window of opportunity where the NC film morphology goes through interesting transformations without large-scale coalescence of the NCs. NC coalescence can be mitigated by depositing a thin film of amorphous silicon (a-Si) on the NC film. Remarkably, pulsed laser annealing of the a-Si/PbSe NC films crystallized the silicon while NC morphology and translational order of the NC film are preserved. © 2011 American Chemical Society.

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

Science.gov (United States)

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

2015-11-01

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

SEM-EDX--a useful tool for forensic examinations

International Nuclear Information System (INIS)

Zadora, G.; Brozek-Mucha, Z.

2003-01-01

There are two main aims of forensic examination of the physical evidences. The first aim is comparison of the evidence with the reference material (called discrimination). The task is to find out whether they could have come from the same object. The second aim, when there is no comparative material available, is a classification of the evidence sample into a group of objects taking into account its specific chemical and physical properties. Scanning electron microscopy with energy dispersive X-ray spectrometry (SEM-EDX) is a powerful tool for forensic scientists to classify and discriminate evidence material because they can simultaneously examine the morphology and the elemental composition of objects. Moreover, the obtained results could be enhanced using some methods of chemometric analysis. A few examples of problems related to the classification and discrimination of selected types of microtraces are presented

Etching microscopic defects in polycarbonate due to high dose ArF or KrF laser exposure

Energy Technology Data Exchange (ETDEWEB)

Jaleh, B. [Physics Department, Bu- Alisina University, Hamadan (Iran, Islamic Republic of); Parvin, P. [Physics Department, Amirkabir University, P.O. Box 15875-4413, Hafez Ave, Tehran (Iran, Islamic Republic of) and Laser Research Center, Atomic Energy Organization of Iran, AEOI, Tehran (Iran, Islamic Republic of) ]. E-mail: parvin@aut.ac.ir; Katoozi, M. [National Radiation Protection Department, AEOI, Tehran (Iran, Islamic Republic of); Zamani, Z. [Laser Research Center, Atomic Energy Organization of Iran, AEOI, Tehran (Iran, Islamic Republic of); Zare, A. [Laser Research Center, Atomic Energy Organization of Iran, AEOI, Tehran (Iran, Islamic Republic of)

2005-11-15

The ArF or KrF excimer laser exposure on the polycarbonate (PC) with corresponding doses higher than {phi}{sub th}5.2J/cm{sup 2}, at 32mJ/cm{sup 2} fluence per pulse and 5Hz pulse repetition rate (PRR), induces regular defects leading to self assembled defect structure following electrochemical etching (ECE). We have observed the conical-like structure for {phi}>{phi}{sub th}, whereas the polymer experiences hardening effect due to crosslinking when {phi}<{phi}{sub th}. Subsequently, conical-like, structure turns into track-like pits developing under ECE multiple treeing. Self assembled defect structure may be seen by naked eye as white spots, despite SEM illustrates a type of periodic pit formation-morphology. The exact explanation of the effect is not well understood yet. It looks like alpha tracks in the polymer surface, however the PC pieces were simply treated by excimer lasers at high doses, and they have not been exposed to the nuclear particles afterwards. We could not observe those effects at 308nm (XeCl laser) or longer wavelengths at 351nm (XeF laser) where UV photoablation does not occur. It indicates that UV ablation establishes surface degradation at shorter wavelengths, leading to laser micro etching. The mean track (defect) density is about one order of magnitude greater than the normal alpha tracks. Increasing UV doses, polymer undergoes a plateau, corresponding to etched defect saturation on PC.

Etching microscopic defects in polycarbonate due to high dose ArF or KrF laser exposure

International Nuclear Information System (INIS)

Jaleh, B.; Parvin, P.; Katoozi, M.; Zamani, Z.; Zare, A.

2005-01-01

The ArF or KrF excimer laser exposure on the polycarbonate (PC) with corresponding doses higher than φ th 5.2J/cm 2 , at 32mJ/cm 2 fluence per pulse and 5Hz pulse repetition rate (PRR), induces regular defects leading to self assembled defect structure following electrochemical etching (ECE). We have observed the conical-like structure for φ>φ th , whereas the polymer experiences hardening effect due to crosslinking when φ th . Subsequently, conical-like, structure turns into track-like pits developing under ECE multiple treeing. Self assembled defect structure may be seen by naked eye as white spots, despite SEM illustrates a type of periodic pit formation-morphology. The exact explanation of the effect is not well understood yet. It looks like alpha tracks in the polymer surface, however the PC pieces were simply treated by excimer lasers at high doses, and they have not been exposed to the nuclear particles afterwards. We could not observe those effects at 308nm (XeCl laser) or longer wavelengths at 351nm (XeF laser) where UV photoablation does not occur. It indicates that UV ablation establishes surface degradation at shorter wavelengths, leading to laser micro etching. The mean track (defect) density is about one order of magnitude greater than the normal alpha tracks. Increasing UV doses, polymer undergoes a plateau, corresponding to etched defect saturation on PC

Low-level lasers affect Escherichia coli cultures in hyperosmotic stress

Science.gov (United States)

Pinheiro, C. C.; Barboza, L. L.; Paoli, F.; Fonseca, A. S.

2015-08-01

Physical characteristics and practical properties have made lasers of interest for biomedical applications. Effects of low-level lasers on biological tissues could occur or be measurable depending on cell type, presence of a pathologic process or whether the cells are in an adverse environment. The objective of this work was to evaluate the survival, morphology and filamentation of E. coli cells proficient and deficient in the repair of oxidative DNA lesions exposed low-level red and infrared lasers submitted to hyperosmotic stress. Wild type and endonuclease VIII deficient E. coli cells in exponential and stationary growth phase were exposed to red and infrared lasers and submitted to hyperosmotic stress. Cell viability, filamentation phenotype and cell morphology were evaluated. Cell viability was not significantly altered but previous laser exposure induced filamentation and an altered area of stressed cells depending on physiologic condition and presence of the DNA repair. Results suggest that previous exposure to low-level red and infrared lasers could not affect viability but induced morphologic changes in cells submitted to hyperosmotic stress depending on physiologic conditions and repair of oxidative DNA lesions.

Laser-induced breakdown spectroscopy of tantalum plasma

International Nuclear Information System (INIS)

Khan, Sidra; Bashir, Shazia; Hayat, Asma; Khaleeq-ur-Rahman, M.; Faizan–ul-Haq

2013-01-01

Laser Induced Breakdown spectroscopy (LIBS) of Tantalum (Ta) plasma has been investigated. For this purpose Q-switched Nd: YAG laser pulses (λ∼ 1064 nm, τ∼ 10 ns) of maximum pulse energy of 100 mJ have been employed as an ablation source. Ta targets were exposed under the ambient environment of various gases of Ar, mixture (CO 2 : N 2 : He), O 2 , N 2 , and He under various filling pressure. The emission spectrum of Ta is observed by using LIBS spectrometer. The emission intensity, excitation temperature, and electron number density of Ta plasma have been evaluated as a function of pressure for various gases. Our experimental results reveal that the optical emission intensity, the electron temperature and density are strongly dependent upon the nature and pressure of ambient environment. The SEM analysis of the ablated Ta target has also been carried out to explore the effect of ambient environment on the laser induced grown structures. The growth of grain like structures in case of molecular gases and cone-formation in case of inert gases is observed. The evaluated plasma parameters by LIBS analysis such as electron temperature and the electron density are well correlated with the surface modification of laser irradiated Ta revealed by SEM analysis

Laser-induced breakdown spectroscopy of tantalum plasma

Energy Technology Data Exchange (ETDEWEB)

Khan, Sidra; Bashir, Shazia; Hayat, Asma; Khaleeq-ur-Rahman, M.; Faizan–ul-Haq [Centre for Advanced Studies in Physics, GC University, Lahore (Pakistan)

2013-07-15

Laser Induced Breakdown spectroscopy (LIBS) of Tantalum (Ta) plasma has been investigated. For this purpose Q-switched Nd: YAG laser pulses (λ∼ 1064 nm, τ∼ 10 ns) of maximum pulse energy of 100 mJ have been employed as an ablation source. Ta targets were exposed under the ambient environment of various gases of Ar, mixture (CO{sub 2}: N{sub 2}: He), O{sub 2}, N{sub 2}, and He under various filling pressure. The emission spectrum of Ta is observed by using LIBS spectrometer. The emission intensity, excitation temperature, and electron number density of Ta plasma have been evaluated as a function of pressure for various gases. Our experimental results reveal that the optical emission intensity, the electron temperature and density are strongly dependent upon the nature and pressure of ambient environment. The SEM analysis of the ablated Ta target has also been carried out to explore the effect of ambient environment on the laser induced grown structures. The growth of grain like structures in case of molecular gases and cone-formation in case of inert gases is observed. The evaluated plasma parameters by LIBS analysis such as electron temperature and the electron density are well correlated with the surface modification of laser irradiated Ta revealed by SEM analysis.

Laser cladding Ni-base composite coating on titanium alloy with pre-placed B4C+NiCoCrAlY

International Nuclear Information System (INIS)

Qingwu Meng; Lin Geng; Zhenzhu Zheng

2005-01-01

Using a CO 2 laser, a process of cladding Ni-base composite coating on Ti6Al4V with pre-placed B 4 C and NiCoCrAlY was studied. A good metallurgical bonding coating without cracks and pores was obtained in reasonable ratio of components and low energy laser process. Morphology and microstructure of the coating were analyzed with OM, XRD, SEM and EDS. It is certain that there was a reaction between B 4 C and Ti during in-situ producing TiB 2 and TiC. The Ni-base composite coating is strengthened with TiB 2 and TiC reinforcement phases. Vickers hardness tester measured that the average microhardness of the coating is HV1200 and it is 3.5 times of the Ti6Al4V substrate. The high hard coating containing several reinforcement phases greatly enhances wear resistance of titanium alloy. (orig.)

Investigation of the surface morphology of ion-bombarded biocompatible materials with a SEM and profilograph

International Nuclear Information System (INIS)

Kowalski, Z.W.

1984-01-01

The surface morphology (topography and roughness) is a very important factor which affects the response of biological tissue to an implant material. The effect of an incident ion beam on surface morphology of various biocompatible materials was studied. All materials were bombarded by Ar + ions at an applied voltage of 7 kV at various incident angles from 0 to 1.4 rad (0 to 80 deg) and at a beam current up to 0.1 mA. The surface topographies of ion-bombarded samples were examined with a Japan Electron Optics Laboratory, model JSM-35, scanning electron microscope. The roughness of the surface was calculated from the shape of a surface profile, which was recorded by a profilograph, the ME 10 (supplied by VEB Carl Zeiss, Jena). (author)

ZrCuAl Bulk Metallic Glass spall induced by laser shock

Science.gov (United States)

Jodar, Benjamin; Loison, Didier; Yokoyama, Yoshihiko; Lescoute, Emilien; Berthe, Laurent; Sangleboeuf, Jean-Christophe

2017-06-01

To face High Velocity Impacts, the aerospace industry is always seeking for innovative materials usable as debris shielding components. Bulk Metallic Glasses (BMG) revealed interesting mechanical properties in case of static and quasi-static loading conditions: high elasticity, high tenacity, low density and high fracture threshold... The department of Mechanics and Glass of the Institut of Physics Rennes conducted on the ELFIE facility, laser shock experiments to study the behavior of a ternary ZrCuAl BMG under high strain rate, up-to fragmentation process. On the one hand, in-situ diagnostics were used to measure ejection velocities with PDV and debris morphologies were observed by Shadowgraphy. On the other hand, spalled areas (dimensions and features) were characterized through post-mortem analysis (optical observations, profilometry and SEM). These results are compared to experimental and numerical data on the crystalline forms of the ZrCuAl basic compounds.

Dichromatic laser radiation effects on DNA of Escherichia coli and plasmids

Science.gov (United States)

Martins, W. A.; Polignano, G. A. C.; Guimarães, O. R.; Geller, M.; Paoli, F.; Fonseca, A. S.

2015-04-01

Dichromatic and consecutive laser radiations have attracted increased attention for clinical applications as offering new tools for the treatment of dysfunctional tissues in situations where monochromatic radiation is not effective. This work evaluated the survival, filamentation and morphology of Escherichia coli cells, and the induction of DNA lesions, in plasmid DNA exposed to low-intensity consecutive dichromatic laser radiation. Exponential and stationary wild type and formamidopyrimidine DNA glycosylase/MutM protein deficient E. coli cultures were exposed to consecutive low-intensity dichromatic laser radiation (infrared laser immediately after red laser) to study the survival, filamentation and morphology of bacterial cells. Plasmid DNA samples were exposed to dichromatic radiation to study DNA lesions by electrophoretic profile. Dichromatic laser radiation affects the survival, filamentation and morphology of E. coli cultures depending on the growth phase and the functional repair mechanism of oxidizing lesions in DNA, but does not induce single/double strands breaks or alkali-labile DNA lesions. Results show that low-intensity consecutive dichromatic laser radiation induces biological effects that differ from those induced by monochromatic laser radiation, suggesting that other therapeutic effects could be obtained using dichromatic radiation.

In-vivo study of adhesion and bone growth around implanted laser groove/RGD-functionalized Ti-6Al-4V pins in rabbit femurs

Energy Technology Data Exchange (ETDEWEB)

Chen, J., E-mail: jianboc@gmail.com [Princeton Institute of Science and Technology of Materials and Department of Mechanical and Aerospace Engineering, Princeton University, Princeton, NJ 08544 (United States); Bly, R.A. [Princeton Institute of Science and Technology of Materials and Department of Mechanical and Aerospace Engineering, Princeton University, Princeton, NJ 08544 (United States); Saad, M.M.; AlKhodary, M.A.; El-Backly, R.M. [Tissue Engineering laboratories, Faculty of Dentistry, Alexandria University, Alexandria (Egypt); Cohen, D.J.; Kattamis, N. [Princeton Institute of Science and Technology of Materials and Department of Mechanical and Aerospace Engineering, Princeton University, Princeton, NJ 08544 (United States); Fatta, M.M.; Moore, W.A. [Tissue Engineering laboratories, Faculty of Dentistry, Alexandria University, Alexandria (Egypt); Arnold, C.B. [Princeton Institute of Science and Technology of Materials and Department of Mechanical and Aerospace Engineering, Princeton University, Princeton, NJ 08544 (United States); Marei, M.K. [Tissue Engineering laboratories, Faculty of Dentistry, Alexandria University, Alexandria (Egypt); Soboyejo, W.O. [Princeton Institute of Science and Technology of Materials and Department of Mechanical and Aerospace Engineering, Princeton University, Princeton, NJ 08544 (United States)

2011-07-20

Titanium surfaces were designed, produced, and evaluated for levels of osseointegration into the femurs of rabbits. A total of 36 Ti-6Al-4V pins (15 mm length, 1.64 mm diameter) were prepared into three experimental groups. These were designed to test the effects of osseointegration on laser grooved, RGD coated, and polished control surfaces, as well as combined effects. Circumferential laser grooves were introduced onto pin surfaces (40 {mu}m spacing) using a UV laser ({lambda} = 355 nm). The tripeptide sequence, Arginine-Glycine-Aspartic acid (RGD), was functionalized onto laser grooved surfaces. Of the prepared samples, surface morphology and chemistry were analyzed using scanning electron microscopy (SEM) and Immunoflourescence (IF) spectroscopy, respectively. The experimental pin surfaces were surgically implanted into rabbit femurs. The samples were then harvested and evaluated histologically. Sections of the sample were preserved in a methylmethacralate mold, sliced via a hard microtome, and polished systematically. In the case of the RGD coated and laser grooved surfaces, histological results showed accelerated bone growth into the implant, pull-out tests were also used to compare the adhesion between bone and the titanium pins with/without laser textures and/or RGD coatings. - Research highlights: {yields} Circumferential laser grooves were introduced onto pin surfaces using a UV laser. {yields} The tripeptide sequence, RGD, was functionalized onto laser grooved surfaces. {yields} The experimental pin surfaces were surgically implanted into rabbit femurs. {yields} RGD coated laser groove surfaces accelerated bone growth into the implant. {yields} RGD coated laser grooved surfaces enhanced the adhesion between the bone and implant.

In-vivo study of adhesion and bone growth around implanted laser groove/RGD-functionalized Ti-6Al-4V pins in rabbit femurs

International Nuclear Information System (INIS)

Chen, J.; Bly, R.A.; Saad, M.M.; AlKhodary, M.A.; El-Backly, R.M.; Cohen, D.J.; Kattamis, N.; Fatta, M.M.; Moore, W.A.; Arnold, C.B.; Marei, M.K.; Soboyejo, W.O.

2011-01-01

Titanium surfaces were designed, produced, and evaluated for levels of osseointegration into the femurs of rabbits. A total of 36 Ti-6Al-4V pins (15 mm length, 1.64 mm diameter) were prepared into three experimental groups. These were designed to test the effects of osseointegration on laser grooved, RGD coated, and polished control surfaces, as well as combined effects. Circumferential laser grooves were introduced onto pin surfaces (40 μm spacing) using a UV laser (λ = 355 nm). The tripeptide sequence, Arginine-Glycine-Aspartic acid (RGD), was functionalized onto laser grooved surfaces. Of the prepared samples, surface morphology and chemistry were analyzed using scanning electron microscopy (SEM) and Immunoflourescence (IF) spectroscopy, respectively. The experimental pin surfaces were surgically implanted into rabbit femurs. The samples were then harvested and evaluated histologically. Sections of the sample were preserved in a methylmethacralate mold, sliced via a hard microtome, and polished systematically. In the case of the RGD coated and laser grooved surfaces, histological results showed accelerated bone growth into the implant, pull-out tests were also used to compare the adhesion between bone and the titanium pins with/without laser textures and/or RGD coatings. - Research highlights: → Circumferential laser grooves were introduced onto pin surfaces using a UV laser. → The tripeptide sequence, RGD, was functionalized onto laser grooved surfaces. → The experimental pin surfaces were surgically implanted into rabbit femurs. → RGD coated laser groove surfaces accelerated bone growth into the implant. → RGD coated laser grooved surfaces enhanced the adhesion between the bone and implant.

Seed morphology and its taxonomic significance in the family malvaceae

International Nuclear Information System (INIS)

Abid, R.; Ather, A.

2016-01-01

The seed morphological studies of 75 taxa belonging to 6 sub-families of the family Malvaceae were carried out from Pakistan. In Pakistan the family Malvaceae is represented by 6 sub-families viz., Byttnerioideae, Dombeyoideae, Malvoideae, Bombacoideae, Helicteroideae and Sterculioideae. The seed macro and micro morphological characters are examined, using light (LM) and scanning electron microscopy (SEM). Detailed seed morphological descriptions, micrographs and keys based on seed characters are also provided. A variety in various quantitative and qualitative seed characters was observed. The micro-morphological characters of seeds are quite significant to strengthen the taxonomic decisions within the family Malvaceae at various levels. The data obtained from the seed morphological characters were analyzed numerically to trace out the phylogenetic affinities for the taxa within the family Malvaceae from Pakistan. (author)

Effect of CO{sub 2}-laser irradiation on properties and performance of thin-film composite polyamide reverse osmosis membrane

Energy Technology Data Exchange (ETDEWEB)

Jahangiri, Foad; Mousavi, Seyyed Abbas; Farhadi, Fathollah; Sabzi, Behnam; Chenari, Zeinab [Sharif University of Technology, Tehran (Iran, Islamic Republic of); Vatanpour, Vahid [Kharazmi (Tarbiat Moallem) University, Tehran (Iran, Islamic Republic of)

2016-03-15

CO{sub 2}-laser irradiation was used to modify the surface properties of thin-film composite (TFC) polyamide reverse osmosis (RO) membranes. These membranes were first synthesized via interfacial polymerization of m-phenylenediamine (MPD) monomers and trimesoyl chloride (TMC) over porous polysulfone ultrafiltration support, followed by a CO{sub 2}-irradiation. AFM, ATR-FTIR, SEM and contact angle measurements were used to characterize the surface properties of these membranes. The ATR-FTIR results indicated that CO{sub 2}-laser irradiation did not induce any functional groups on the membrane surface. However, it was found that the laser irradiation enhanced the NaCl salt rejection and slightly reduced the permeate flux. Moreover, the maintenance of the flux in modified membranes was much higher than untreated ones. Specially, after 180 min of filtration, the reduction in initial flux for the unmodified membranes was 22%. However, the reduction in initial flux for the modified membranes was less than 5%. Bovine serum albumin (BSA) filtration revealed an improvement in the antifouling properties of the modified membranes. The changes in the membrane surface morphology showed that the roughness of membrane surface is reduced significantly.

LASER-INDUCED BIOACTIVITY IN DENTAL PORCELAIN MODIFIED BY BIOACTIVE GLASS

Directory of Open Access Journals (Sweden)

ANASTASIA BEKETOVA

2012-12-01

Full Text Available The aim of this study was to investigate the impact of laser-liquid-solid interaction method in the bioactivity of dental porcelain modified by bioactive glass. Forty sol-gel derived specimens were immersed in Dulbecco's Modified Eagle's Medium, 31 and 9 specimens of which were treated with Er:YAG and Nd:YAG laser respectively. Untreated specimens served as controls. Incubation of specimens followed. Bioactivity was evaluated, using Fourier Transform Infrared spectroscopy (FTIR, Scanning Electron Microscopy (SEM/Energy Dispersive Spectroscopy (EDS and Transmission Electron Microscopy (TEM. FTIR detected peaks associated with hydroxyapatite on 1 Nd:YAG- and 4 Er:YAG-treated specimens. SEM analysis revealed that Er:YAG-treated specimens were covered by granular hydroxyapatite layer, while Nd:YAG treated specimen presented growth of flake-like hydroxyapatite. TEM confirmed the results. The untreated controls presented delayed bioactivity. In conclusion, Nd:YAG and Er:YAG laser treatment of the material, under certain fluencies, accelerates hydroxyapatite formation. Nd:YAG laser treatment of specific parameters causes the precipitation of flake-like hydroxyapatite in nano-scale.

The effect of NO3- and OH- ions on the laser ablation of Cs+ ion on Type 304 stainless steel

International Nuclear Information System (INIS)

Hui-Jun Won; Jei-Kwon Moon; Chong-Hun Jung; Kune-Woo Lee; Jae-Hyuk Hyun

2011-01-01

Type 304 stainless steel specimens artificially contaminated with CsCl solution were treated with KOH solution and KNO 3 solution, respectively. Cs + ion removal tests by a Q-switched Nd:YAG laser at 1064 nm at a given fluence of 57.3 J/cm 2 were performed. The surface morphology and the relative atomic mole ratio of the specimen surface were investigated by SEM and EPMA. The order of Cs + ion removal efficiency of laser was no-treatment 3 during the 42 shots. From the investigation of XPS peaks around 532.7 and 292.9 eV, KNO 3 on a surface of specimen was found to be fully decomposed during the laser irradiation. It was suggested that Cs 2 O particulates formed by the reaction between the reactive oxygen generated from the nitrate ion and Cs + ion on the metal surface could be easily suspended. For the KOH system, FeOOH was formed during the laser irradiation and it changed into Fe 2 O 3 . It was also suggested that Cs 2 O particulates were formed by the reaction between the reactive oxygen generated from the decomposition of K 2 O and Cs + ion on the metal surface. (author)

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

Science.gov (United States)

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

2017-06-01

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

Laser Decontamination of Surfaces Contaminated with Cs+ Ion

International Nuclear Information System (INIS)

Baigalmaaa, B.; Won, H. J.; Moon, J. K.; Jung, C. H.; Lee, K. W.; Hyun, J. H.

2008-01-01

Laser decontamination technology has been proven to be an efficient method for a surface modification of metals and concretes contaminated with radioactive isotopes. Furthermore, the generation of a secondary waste is negligible. The radioactivity of hot cells in the DFDF (Dupic Fuel Development Facility) is presumed to be very high and the predominant radionuclide is Cs-137. A series of laser decontamination studies by a fabricated Q-switched Nd:YAG laser system were performed on stainless steel specimens artificially contaminated with Cs+ ion. Decontamination characteristics of the stainless steel were analyzed by SEM and EPMA

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

Science.gov (United States)

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

2014-03-01

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

Surface morphologies of He-implanted tungsten

Energy Technology Data Exchange (ETDEWEB)

Bannister, M.E., E-mail: bannisterme@ornl.gov [Physics Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831-6371 (United States); Meyer, F.W.; Hijazi, H. [Physics Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831-6371 (United States); Unocic, K.A.; Garrison, L.M.; Parish, C.M. [Materials Science and Technology Division, Oak Ridge National Laboratory, Oak Ridge, TN (United States)

2016-09-01

Surface morphologies of tungsten surfaces, both polycrystalline and single-crystal [1 1 0], were investigated using SEM and FIB/SEM techniques after implantations at elevated surfaces temperatures (1200–1300 K) using well-characterized, mono-energetic He ion beams with a wide range of ion energies (218 eV–250 keV). Nanofuzz was observed on polycrystalline tungsten (PCW) following implantation of 100-keV He ions at a flux threshold of 0.9 × 10{sup 16} cm{sup −2} s{sup −1}, but not following 200-keV implantations with similar fluxes. No nanofuzz formation was observed on single-crystal [1 1 0] tungsten (SCW), despite fluxes exceeding those demonstrated previously to produce nanofuzz on polycrystalline tungsten. Pre-damaging the single-crystal tungsten with implanted C impurity interstitials did not significantly affect the surface morphologies resulting from the high-flux He ion implantations. The main factor leading to the different observed surface structures for the pristine and C-implanted single-crystal W samples appeared to be the peak He ion flux characterizing the different exposures. It was speculated that nanofuzz formation was not observed for any SCW target exposures because of increased incubation fluences required for such targets.

Fractional laser-assisted drug uptake

DEFF Research Database (Denmark)

Banzhaf, Christina A; Thaysen-Petersen, Daniel; Bay, Christiane

2017-01-01

BACKGROUND AND OBJECTIVE: Ablative fractional laser (AFXL) is acknowledged to increase uptake of topically applied agents in skin. AFXL channels gradually close over time, which may impair this capability. The time frame for applying a drug after AFXL exposure remains to be established. The aim...... in laser-exposed and non-laser-exposed skin at 24-48 hours. CONCLUSIONS: The time frame to maintain enhanced drug delivery sustained for several hours after AFXL exposure, corresponding to channel morphology and loss of skin integrity. Lasers Surg. Med. 49:348-354, 2017. © 2016 Wiley Periodicals, Inc....

Influence of the Overlapping Factor and Welding Speed on T-Joint Welding of Ti6Al4V and Inconel 600 Using Low-Power Fiber Laser

Directory of Open Access Journals (Sweden)

Shamini Janasekaran

2016-06-01

Full Text Available Double-sided laser beam welding of skin-stringer joints is an established method for many applications. However, in certain cases with limited accessibility, single-sided laser beam joining is considered. In the present study, single-sided welding of titanium alloy Ti6Al4V and nickel-based alloy Inconel 600 in a T-joint configuration was carried out using continuous-wave (CW, low-power Ytterbium (Yb-fiber laser. The influence of the overlapping factor and welding speed of the laser beam on weld morphology and properties was investigated using scanning electron microscopy (SEM and X-ray diffraction (XRD, respectively. XRD analysis revealed the presence of intermetallic layers containing NiTi and NiTi2 at the skin-stringer joint. The strength of the joints was evaluated using pull testing, while the hardness of the joints was analyzed using Vickers hardness measurement at the base metal (BM, fusion zone (FZ and heat-affected zone (HAZ. The results showed that the highest force needed to break the samples apart was approximately 150 N at a laser welding power of 250 W, welding speed of 40 mm/s and overlapping factor of 50%. During low-power single-sided laser welding, the properties of the T-joints were affected by the overlapping factor and laser welding speed.

Plasmonic laser printing for functional metasurfaces

DEFF Research Database (Denmark)

Zhu, Xiaolong; Carstensen, M. S.; Vannahme, Christoph

2016-01-01

Recently, we show a method of color printing on nanoimprinted plasmonic metasurfaces using laser post-writing. Laser pulses induce transient local heat generation that leads to melting and reshaping of the imprinted nanostructures [1]. Depending on the laser pulse energy density, different surface...... morphologies that support different plasmonic resonances can be created. This technology creates a laser printer capable of producing color images with a resolution up to 127,000 DPI. With tailored trains of laser pulses, multiple optical states are flatiron onto the metasurface film with a nanoscale...

Laser welding of NiTi shape memory alloy: Comparison of the similar and dissimilar joints to AISI 304 stainless steel

Science.gov (United States)

Mirshekari, G. R.; Saatchi, A.; Kermanpur, A.; Sadrnezhaad, S. K.

2013-12-01

The unique properties of NiTi alloy, such as its shape memory effect, super-elasticity and biocompatibility, make it ideal material for various applications such as aerospace, micro-electronics and medical device. In order to meet the requirement of increasing applications, great attention has been given to joining of this material to itself and to other materials during past few years. Laser welding has been known as a suitable joining technique for NiTi shape memory alloy. Hence, in this work, a comparative study on laser welding of NiTi wire to itself and to AISI 304 austenitic stainless steel wire has been made. Microstructures, mechanical properties and fracture morphologies of the laser joints were investigated using optical microscopy, scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), X-ray diffraction analysis (XRD), Vickers microhardness (HV0.2) and tensile testing techniques. The results showed that the NiTi-NiTi laser joint reached about 63% of the ultimate tensile strength of the as-received NiTi wire (i.e. 835 MPa) with rupture strain of about 16%. This joint also enabled the possibility to benefit from the pseudo-elastic properties of the NiTi component. However, tensile strength and ductility decreased significantly after dissimilar laser welding of NiTi to stainless steel due to the formation of brittle intermetallic compounds in the weld zone during laser welding. Therefore, a suitable modification process is required for improvement of the joint properties of the dissimilar welded wires.

Plasmonic colour laser printing

DEFF Research Database (Denmark)

Zhu, Xiaolong; Vannahme, Christoph; Højlund-Nielsen, Emil

2016-01-01

-beam lithography (EBL) or focused ion beam (FIB), both expensive and not scalable processes that are not suitable for post-processing customization. Here we show a method of colour printing on nanoimprinted plasmonic metasurfaces using laser post-writing. Laser pulses induce transient local heat generation...... that leads to melting and reshaping of the imprinted nanostructures. Depending on the laser pulse energy density, different surface morphologies that support different plasmonic resonances leading to different colour appearances can be created. Using this technique we can print all primary colours...

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

Energy Technology Data Exchange (ETDEWEB)

Bao, Jiading; Long, Yuhong, E-mail: longyuhong@guet.edu.cn; Tong, Youqun; Yang, Xiaoqing; Zhang, Bin; Zhou, Zupeng

2016-11-30

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

New morphological data on Cucullanus pinnai pinnai (Nematoda) parasitizing Pimelodus maculatus (Pimelodidae) in southeastern Brazil.

Science.gov (United States)

Vieira, Vivian Suane de Freitas; Vieira, Fabiano Matos; Luque, José Luis

2015-01-01

This paper describes the morphology of Cucullanus pinnai pinnai parasitizing Pimelodus maculatus in the Guandu River, Brazil, based on differential interference contrast (DIC) microscopy and scanning electron microscopy (SEM), providing new morphological data about this species of parasite. Nematodes were collected between May and October 2012 from specimens of Pimelodus maculatus in the Guandu River (22°48'2"S, 43°37'35"W), in the state of Rio de Janeiro, Brazil. Some characteristics of specimens of Cucullanus in this study fall within the range of morphological variations of previously studied C. pinnai pinnai. Most of the specimens studied here had excretory pore and deirids located at the posterior end of the oesophagus, a feature not recorded in previous studies of this species. In addition, the size of the gubernaculum was larger than the other specimens previously studied. The SEM and DIC analyses of C. pinnai revealed several morphological details of the cephalic region and the tail papillae. With regard to the polymorphism of C. pinnai, morphological and genetic studies of this cucullanid nematode are needed, involving large numbers of host species and a wide geographical distribution.

Micro-Bulges Investigation on Laser Modified Tool Steel Surface

Directory of Open Access Journals (Sweden)

Fauzun Fazliana

2017-01-01

Full Text Available This paper presents micro-bulges investigation on laser modified tool steel. The aim of this study is to understand the effect of laser irradiance and interaction time on surface morphology configuration. An Nd:YAG laser system with TEM00 pulse processing mode was used to modify the samples. Metallographic study shows samples were analyzed for focal position effect on melted pool size, angle of peaks geometry and laser modified layer depth. Surface morphology were analyzed for surface roughness. Laser modified layer shows depth ranged between 42.22 and 420.12 μm. Angle of peak bulge was found to be increase with increasing peak power. The maximum roughness, Ra, achieved in modified H13 was 21.10 μm. These findings are significant to enhance surface properties of laser modified steel and cast iron for dies and high wear resistance applications.

Laser irradiation of carbon–tungsten materials

International Nuclear Information System (INIS)

Marcu, A; Lungu, C P; Ursescu, D; Porosnicu, C; Grigoriu, C; Avotina, L; Kizane, G; Marin, A; Osiceanu, P; Grigorescu, C E A; Demitri, N

2014-01-01

Carbon–tungsten layers deposited on graphite by thermionic vacuum arc (TVA) were directly irradiated with a femtosecond terawatt laser. The morphological and structural changes produced in the irradiated area by different numbers of pulses were systematically explored, both along the spots and in their depths. Although micro-Raman and Synchrotron-x-ray diffraction investigations have shown no carbide formation, they have shown the unexpected presence of embedded nano-diamonds in the areas irradiated with high fluencies. Scanning electron microscopy images show a cumulative effect of the laser pulses on the morphology through the ablation process. The micro-Raman spatial mapping signalled an increased percentage of sp 3 carbon bonding in the areas irradiated with laser fluencies around the ablation threshold. In-depth x-ray photoelectron spectroscopy investigations suggested a weak cumulative effect on the percentage increase of the sp 2 -sp 3 transitions with the number of laser pulses just for nanometric layer thicknesses. (paper)

Formation of silicon carbide by laser ablation in graphene oxide-N-methyl-2-pyrrolidone suspension on silicon surface

Science.gov (United States)

Jaleh, Babak; Ghasemi, Samaneh; Torkamany, Mohammad Javad; Salehzadeh, Sadegh; Maleki, Farahnaz

2018-01-01

Laser ablation of a silicon wafer in graphene oxide-N-methyl-2-pyrrolidone (GO-NMP) suspension was carried out with a pulsed Nd:YAG laser (pulse duration = 250 ns, wavelength = 1064 nm). The surface of silicon wafer before and after laser ablation was studied using optical microscopy, scanning electron microscopy (SEM) and energy dispersive X-ray analysis (EDX). The results showed that the ablation of silicon surface in liquid by pulsed laser was done by the process of melt expulsion under the influence of the confined plasma-induced pressure or shock wave trapped between the silicon wafer and the liquid. The X-ray diffraction‌ (XRD) pattern of Si wafer after laser ablation showed that 4H-SiC layer is formed on its surface. The formation of the above layer was also confirmed by Raman spectroscopy, and X-ray photoelectron spectroscopy‌ (XPS), as well as EDX was utilized. The reflectance of samples decreased with increasing pulse energy. Therefore, the morphological alteration and the formation of SiC layer at high energy increase absorption intensity in the UV‌-vis regions. Theoretical calculations confirm that the formation of silicon carbide from graphene oxide and silicon wafer is considerably endothermic. Development of new methods for increasing the reflectance without causing harmful effects is still an important issue for crystalline Si solar cells. By using the method described in this paper, the optical properties of solar cells can be improved.

Shadowgraph studies of laser-assisted non-thermal structuring of thin layers on flexible substrates by shock-wave-induced delamination processes

Energy Technology Data Exchange (ETDEWEB)

Lorenz, Pierre, E-mail: pierre.lorenz@iom-leipzig.de [Leibniz-Institut für Oberflächenmodifizierung e. V., Permoserstraße 15, 04318 Leipzig (Germany); Smausz, Tomi [Department of Optics and Quantum Electronics, University of Szeged, H-6720 Szeged, Dóm tér 9 (Hungary); MTA-SZTE Research Group on Photoacoustic Spectroscopy, University of Szeged, H-6720 Szeged, Dóm tér 9 (Hungary); Csizmadia, Tamas [Department of Optics and Quantum Electronics, University of Szeged, H-6720 Szeged, Dóm tér 9 (Hungary); Ehrhardt, Martin; Zimmer, Klaus [Leibniz-Institut für Oberflächenmodifizierung e. V., Permoserstraße 15, 04318 Leipzig (Germany); Hopp, Bela [Department of Optics and Quantum Electronics, University of Szeged, H-6720 Szeged, Dóm tér 9 (Hungary)

2015-05-01

Highlights: • The shock-wave-induced film delamination (SWIFD) is a laser patterning process. • The SWIFD process of CIGS solar cells was studied by shadowgraph measurements. • The study presented that SWIFD allows the structuring of CIGS solar cells. • The dynamics of the delamination process was analyzed. - Abstract: The laser-assisted microstructuring of thin films especially for electronic applications without damaging the layers or the substrates is a challenge for the laser micromachining techniques. The laser-induced thin-film patterning by ablation of the polymer substrate at the rear side that is called ‘SWIFD’ – shock-wave-induced film delamination patterning has been demonstrated. This study focuses on the temporal sequence of processes that characterize the mechanism of this SWIFD process on a copper indium gallium selenide (CIGS) solar cell stacks on polyimide. For this purpose high-speed shadowgraph experiments were performed in a pump probe experimental set-up using a KrF excimer laser for ablating the rear side of the polyimide substrate and measuring the shock wave generation at laser ablation of the polymer substrate as well as the thin-film delamination. The morphology and size of the thin-film structures were studied by scanning electron microscopy (SEM). Furthermore, the composition after the laser treatment was analyzed by energy dispersive X-ray (EDX) spectroscopy. The shadowgraph experiments allow the time-dependent identification and evaluation of the shock wave formation, substrate bending, and delamination of the thin film in dependence on the laser parameters. These results will contribute to improve the physical understanding of the laser-induced delamination effect for thin-film patterning.

FIB-SEM tomography in biology.

Science.gov (United States)

Kizilyaprak, Caroline; Bittermann, Anne Greet; Daraspe, Jean; Humbel, Bruno M

2014-01-01

Three-dimensional information is much easier to understand than a set of two-dimensional images. Therefore a layman is thrilled by the pseudo-3D image taken in a scanning electron microscope (SEM) while, when seeing a transmission electron micrograph, his imagination is challenged. First approaches to gain insight in the third dimension were to make serial microtome sections of a region of interest (ROI) and then building a model of the object. Serial microtome sectioning is a tedious and skill-demanding work and therefore seldom done. In the last two decades with the increase of computer power, sophisticated display options, and the development of new instruments, an SEM with a built-in microtome as well as a focused ion beam scanning electron microscope (FIB-SEM), serial sectioning, and 3D analysis has become far easier and faster.Due to the relief like topology of the microtome trimmed block face of resin-embedded tissue, the ROI can be searched in the secondary electron mode, and at the selected spot, the ROI is prepared with the ion beam for 3D analysis. For FIB-SEM tomography, a thin slice is removed with the ion beam and the newly exposed face is imaged with the electron beam, usually by recording the backscattered electrons. The process, also called "slice and view," is repeated until the desired volume is imaged.As FIB-SEM allows 3D imaging of biological fine structure at high resolution of only small volumes, it is crucial to perform slice and view at carefully selected spots. Finding the region of interest is therefore a prerequisite for meaningful imaging. Thin layer plastification of biofilms offers direct access to the original sample surface and allows the selection of an ROI for site-specific FIB-SEM tomography just by its pronounced topographic features.

Morphological characteristics of the optic nerve evaluated by confocal laser tomography (HRT3) and laser polarimetry (GDx-VCC) in a normal population from the city of Barcelona.

Science.gov (United States)

Fallon, M; Pazos, M; Morilla, A; Sebastián, M A; Xancó, R; Mora, C; Calderón, B; Vega, Z; Antón, A

2015-11-01

To evaluate morphological parameters of optic disc and retinal nerve fiber layer (RNFL) examined with confocal laser tomography (HRT3) and laser polarimetry (GDx-VCC) in a normal population, and analyze correlations of these parameters with demographic variables. Cross-sectional study in the context of a glaucoma screening campaign in the primary care center of Barcelona. The individuals selected were non-hypertensive Mediterranean Caucasians with risk for glaucoma development (individuals≥60 years old or≥40 years old with family history of glaucoma or intraocular pressure or myopia>3diopter). All subjects underwent a complete ophthalmic examination, confocal laser tomography (HRT3) and scanning laser polarimetry (GDX-VCC), subjects with results within normal limits only being included. Structural parameters were analyzed along with age, refraction, and pachymetry based on the Spearman rank correlation test. A total of 224 subjects included, with a mean age of 63.4±11.1 years. Disc areas, excavation and ring area were 2.14±0.52mm(2), 0.44±0.34mm (2) and 1.69±0.38mm(2), respectively. The mean RNFL (GDX) was 55.9±6.9μm. Age was correlated with lower ring volume, highest rate of cup shape measure, largest mean and maximum cup depth, lower nerve fiber index (NFI) and RNFL (all p-values below .05). The mean values and distribution of several parameters of the papilla and the RNFL in normal Mediterranean Caucasians population are presented. A loss of thickness of the RNFL, ring thinning, and enlarged cup was observed with increased age. Copyright © 2014 Sociedad Española de Oftalmología. Published by Elsevier España, S.L.U. All rights reserved.

Effect of laser beam parameters on magnetic properties of Nd-Fe-B thick-film magnets fabricated by pulsed laser deposition

International Nuclear Information System (INIS)

Fukunaga, H.; Nakano, M.; Yanai, T.; Kamikawatoko, T.; Yamashita, F.

2011-01-01

The effects of varying the laser power and the spot diameter of a laser beam on the magnetic properties, morphology, and deposition rate of Nd-Fe-B thick-film magnets fabricated by pulsed laser deposition (PLD) were investigated. Reducing the laser fluence on the target reduces the remanence and increases the Nd content and consequently the coercivity of the prepared films. The spot size of the laser beam was found to affect the film surface morphology, the deposition rate, and the reproducibility of the magnetic properties of the prepared films. Reducing the spot size reduces the number of droplets and the reproducibility of the magnetic properties and increases the droplet size. Controlling the spot size of the laser beam enabled us to maximize the deposition rate. Consequently, a coercivity of 1210 kA/m and a remanence of 0.51 T were obtained at a deposition rate of 11.8 μm/(h·W). This deposition rate is 30% greater than the highest previously reported deposition rate by PLD.

Morphology Evolution of Polycarbonate-Polystyrene Blends During Compounding

DEFF Research Database (Denmark)

Chuai, Chengzhi; Almdal, Kristoffer; Johannsen, Ib

2001-01-01

The morphology evolution of polycarbonate-polystyrene (PC/PS) blends during the compounding process in three blending methods of industrial relevance, namely melt blending, re-melt blending in a twin-screw extruder and tri-melt blending in an injection-moulding machine, was investigated using......-empirical model. The results show that the formation of co-continuous morphology strongly depends on blend composition and melt blending method, whereas the model prediction for phase inversion deviates from the experimental values. Further, we found that the initial mechanism of morphology evolution involves...... scanning electron microscopy (SEM) Co examine nine blend compositions. Blends were prepared at compositions where phase inversion was expected to occur according to model predictions. The experimental results were compared to the values of the point of phase inversion calculated with the semi...

Morphological change study on root surfaces treated with curettes, sonic instruments or Er:YAG laser; Estudo in vitro da alteracao morfologica em superficie radicular tratada com curetas, aparelho ultrasonico ou com laser de Er:YAG

Energy Technology Data Exchange (ETDEWEB)

Guimaraes Filho, Arlindo Lopes

2004-07-01

Periodontal disease is caused by dental plaque and dental calculus on roots surfaces, specially on cervical areas. As dental plaque is the main cause and dental calculus a secondary one, it is practically impossible to separate one factor to the other one. In order to get periodontal tissue health it is necessary to eliminate dental plaque and calculus from root surfaces. In this sense, Er:YAG laser comes in as an excellent way to control periodontal disease, not only, by removing calculus and dental plaque but also for its bacteria reduction. The aim of this study is to compare, by S.E.M., root surfaces changing when they are treated with curettes and ultrasonic scaling or Er:YAG laser irradiation with two different energy levels of 60 mJ/pulse and 100 mJ/pulse and repetition tax of 10 Hz (in the display). It is also objective of this study to check a possible thermic damage to pulp tissue when the roots surfaces are irradiated with Er:YAG laser. We used for this study, five human dental roots, each one of them were cut into four samples, giving us a total of twenty samples, which were divided in five groups of four samples each one. The control group, we did not indicated any kind of treatment. The first group, the roots samples were scaled and planned with Gracey curettes 5/6 and 7/8. The second group, the roots samples were treated with ultrasonic instruments. The third group was irradiated with Er:YAG laser using 60 mJ/pulse , 10 Hz and energy density of 4 J/cm{sup 2} (approximated). The fourth group was irradiated with Er:YAG laser using 100 mJ/pulse, 10 Hz and energy density of 7 J/cm{sup 2} (approximated). The results analysis showed that roots scaling either with Gracey curettes or with ultrasonic instruments created smear layer covering roots surfaces; roots surfaces irradiated with Er:YAG laser showed few roughness in the third group; roots surfaces irradiated with Er:YAG laser showed no smear layer and the Er:YAG laser irradiation did not bring any

Sexual Arousal and Sexually Explicit Media (SEM)

DEFF Research Database (Denmark)

Hald, Gert Martin; Stulhofer, Aleksandar; Lange, Theis

2018-01-01

-mainstream and mainstream SEM groups, and (iii) to explore the validity and predictive accuracy of the Non-Mainstream Pornography Arousal Scale (NPAS). METHODS: Online cross-sectional survey of 2,035 regular SEM users in Croatia. MAIN OUTCOMES MEASURES: Patterns of sexual arousal to 27 different SEM themes, sexual...

Scanning electron microscopic (Sem studies on fourth instar larva and pupa of Anopheles (Cellia stephensi Liston (Anophelinae: Culicidae

Directory of Open Access Journals (Sweden)

Jagbir Singh Kirti

2014-12-01

Full Text Available Anopheles (Cellia stephensi Liston is a major vector species of malaria in Indian subcontinent. Taxonomists have worked on its various morphological aspects and immature stages to explore additional and new taxonomic attributes. Scanning electron microscopic (SEM studies have been conducted on the fourth instar larva and pupa of An. stephensi to find additional taxonomic features for the first time from Punjab state.

Effects of Laser Operating Parameters on Piezoelectric Substrates Micromachining with Picosecond Laser

Directory of Open Access Journals (Sweden)

Lamia EL Fissi

2014-12-01

Full Text Available Ten picoseconds (200 kHz ultrafast laser micro-structuring of piezoelectric substrates including AT-cut quartz, Lithium Niobate and Lithium Tantalate have been studied for the purpose of piezoelectric devices application ranging from surface acoustic wave devices, e.g., bandpass filters, to photonic devices such as optical waveguides and holograms. The study examines the impact of changing several laser parameters on the resulting microstructural shapes and morphology. The micromachining rate has been observed to be strongly dependent on the operating parameters, such as the pulse fluence, the scan speed and the scan number. The results specifically indicate that ablation at low fluence and low speed scan tends to form a U-shaped cross-section, while a V-shaped profile can be obtained by using a high fluence and a high scan speed. The evolution of surface morphology revealed that laser pulses overlap in a range around 93% for both Lithium Niobate (LiNbO3 and Lithium Tantalate (LiTaO3 and 98% for AT-cut quartz can help to achieve optimal residual surface roughness.

Effects of laser power density and initial grain size in laser shock punching of pure copper foil

Science.gov (United States)

Zheng, Chao; Zhang, Xiu; Zhang, Yiliang; Ji, Zhong; Luan, Yiguo; Song, Libin

2018-06-01

The effects of laser power density and initial grain size on forming quality of holes in laser shock punching process were investigated in the present study. Three different initial grain sizes as well as three levels of laser power densities were provided, and then laser shock punching experiments of T2 copper foil were conducted. Based upon the experimental results, the characteristics of shape accuracy, fracture surface morphology and microstructures of punched holes were examined. It is revealed that the initial grain size has a noticeable effect on forming quality of holes punched by laser shock. The shape accuracy of punched holes degrades with the increase of grain size. As the laser power density is enhanced, the shape accuracy can be improved except for the case in which the ratio of foil thickness to initial grain size is approximately equal to 1. Compared with the fracture surface morphology in the quasistatic loading conditions, the fracture surface after laser shock can be divided into three zones including rollover, shearing and burr. The distribution of the above three zones strongly relates with the initial grain size. When the laser power density is enhanced, the shearing depth is not increased, but even diminishes in some cases. There is no obvious change of microstructures with the enhancement of laser power density. However, while the initial grain size is close to the foil thickness, single-crystal shear deformation may occur, suggesting that the ratio of foil thickness to initial grain size has an important impact on deformation behavior of metal foil in laser shock punching process.

Surface studies on benzophenone doped PDMS microstructures fabricated using KrF excimer laser direct write lithography

International Nuclear Information System (INIS)

Kant, Madhushree Bute; Shinde, Shashikant D.; Bodas, Dhananjay; Patil, K.R.; Sathe, V.G.; Adhi, K.P.; Gosavi, S.W.

2014-01-01

Graphical abstract: - Highlights: • Use of KrF Laser micromachining for Lab-On-Chip applications at lower fluence. • Addition of Benzophenone in PDMS enhances its self development sensitivity. • Benzophenone helps efficient energy transfer for equal density of bond scissioning. • Correlation of chemical composition with laser dose and microstructure. • Microstructures with well defined clean sidewalls. - Abstract: This paper discusses microfabrication process for benzophenone doped polydimethylsiloxane (PDMS) using laser lithography. KrF excimer laser of 248 nm with 20 ns pulse width at repetition rate of 1 Hz was used for microfabrication of undoped and benzophenone doped PDMS. The doped-PDMS shows sensitivity below 365 nm, permitting processing under ambient light. The analysis of etch depth revealed that doped PDMS shows self developable sensitivity at lower fluence of ∼250 mJ/cm 2 . The unexposed and exposed surface was studied using Fourier transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS), Raman spectroscopy and Scanning electron microscopy (SEM). Spectrocopic analysis indicated increase in C-O, C=O, Si-O 3 and Si-O 4 bonding at the expense of Si-C and Si-O 2 bonds of PDMS. In case of laser exposed doped-PDMS, removal of benzophenone from probe depth of spectroscopy was observed. Whereas the surface morphology of exposed and unexposed doped-PDMS was observed to be same, indicating clean development of PDMS micropatterns. The present study indicates that addition of 3.0 wt.% benzophenone in PDMS enhance self development sensitivity of PDMS. The self developable results on doped-PDMS are quite encouraging for its potential use in point of care Lab-On-Chip applications, for fabricating micropatterns using direct write laser lithography technology

Determination of Fission Gas Inclusion Pressures in High Burnup Nuclear Fuel using Laser Ablation ICP-MS combined with SEM/EPMA and Optical Microscopy

International Nuclear Information System (INIS)

Horvath, Matthias I.; Guenther-Leopold, Ines; Kivel, Niko; Restani, Renato; Guillong, Marcel; Izmer, Andrei; Hellwig, Christian; Guenther, Detlef

2008-01-01

In approximately 20% of all fissions at least one of the fission products is gaseous. These are mainly xenon and krypton isotopes contributing up to 90% by the xenon isotopes. Upon reaching a burn-up of 60 - 75 GWd/tHM a so called High Burnup Structure (HBS) is formed in the cooler rim of the fuel. In this region a depletion of the noble fission gases (FG) in the matrix and an enrichment of FG in μm-sized pores can be observed. Recent calculations show that in these pores the pressure at room temperature can be as large as 30 MPa. The knowledge of the FG pressure in pores is important to understand the high burn-up fuel behavior under accident conditions (i.e. RIA or LOCA). With analytical methods routinely used for the characterization of solid samples, i.e. Electron Probe Micro Analysis (EPMA), Secondary Ion Mass Spectrometry (SIMS), the quantification of gaseous inclusions is very difficult to almost impossible. The combination of a laser ablation system (LA) with an inductively coupled plasma mass spectrometer (ICP-MS) offers a powerful tool for quantification of the gaseous pore inventory. This method offers the advantages of high spatial resolution with laser spot sizes down to 10 μm and low detection limits. By coupling with scanning electron microscopy (SEM) for the pore size distribution, EPMA for the FG inventory in the fuel matrix and optical microscopy for the LA-crater sizes, the pressures in the pores and porosity was calculated. As a first application of this calibration technique for gases, measurements were performed on pressurized water reactor (PWR) fuel with a rod average of 105 GWd/tHM to determine the local FG pressure distribution. (authors)

Improved resolution by mounting of tissue sections for laser microdissection.

Science.gov (United States)

van Dijk, M C R F; Rombout, P D M; Dijkman, H B P M; Ruiter, D J; Bernsen, M R

2003-08-01

Laser microbeam microdissection has greatly facilitated the procurement of specific cell populations from tissue sections. However, the fact that a coverslip is not used means that the morphology of the tissue sections is often poor. To develop a mounting method that greatly improves the morphological quality of tissue sections for laser microbeam microdissection purposes so that the identification of target cells can be facilitated. Fresh frozen tissue and formalin fixed, paraffin wax embedded tissue specimens were used to test the morphological quality of mounted and unmounted tissue. The mounting solution consisted of an adhesive gum and blue ink diluted in water. Interference of the mounting solution with DNA quality was analysed by the polymerase chain reaction using 10-2000 cells isolated by microdissection from mounted and unmounted tissue. The mounting solution greatly improved the morphology of tissue sections for laser microdissection purposes and had no detrimental effects on the isolation and efficiency of amplification of DNA. One disadvantage was that the mounting solution reduced the cutting efficiency of the ultraviolet laser. To minimise this effect, the mounting solution should be diluted as much as possible. Furthermore, the addition of blue ink to the mounting medium restores the cutting efficiency of the laser. The mounting solution is easy to prepare and apply and can be combined with various staining methods without compromising the quality of the DNA extracted.

Quantitating morphological changes in biological samples during scanning electron microscopy sample preparation with correlative super-resolution microscopy.

Science.gov (United States)

Zhang, Ying; Huang, Tao; Jorgens, Danielle M; Nickerson, Andrew; Lin, Li-Jung; Pelz, Joshua; Gray, Joe W; López, Claudia S; Nan, Xiaolin

2017-01-01

Sample preparation is critical to biological electron microscopy (EM), and there have been continuous efforts on optimizing the procedures to best preserve structures of interest in the sample. However, a quantitative characterization of the morphological changes associated with each step in EM sample preparation is currently lacking. Using correlative EM and superresolution microscopy (SRM), we have examined the effects of different drying methods as well as osmium tetroxide (OsO4) post-fixation on cell morphology during scanning electron microscopy (SEM) sample preparation. Here, SRM images of the sample acquired under hydrated conditions were used as a baseline for evaluating morphological changes as the sample went through SEM sample processing. We found that both chemical drying and critical point drying lead to a mild cellular boundary retraction of ~60 nm. Post-fixation by OsO4 causes at least 40 nm additional boundary retraction. We also found that coating coverslips with adhesion molecules such as fibronectin prior to cell plating helps reduce cell distortion from OsO4 post-fixation. These quantitative measurements offer useful information for identifying causes of cell distortions in SEM sample preparation and improving current procedures.

Interaction of CO2 laser-modified nylon with osteoblast cells in relation to wettability

International Nuclear Information System (INIS)

Waugh, D.G.; Lawrence, J.; Morgan, D.J.; Thomas, C.L.

2009-01-01

It has been amply demonstrated previously that CO 2 lasers hold the ability to surface modify various polymers. In addition, it has been observed that these surface enhancements can augment the biomimetic nature of the laser irradiated materials. This research has employed a CO 2 laser marker to produce trench and hatch topographical patterns with peak heights of around 1 μm on the surface of nylon 6,6. The patterns generated have been analysed using white light interferometry, optical microscopy and X-ray photoelectron spectroscopy was employed to determine the surface oxygen content. Contact angle measurements were used to characterize each sample in terms of wettability. Generally, it was seen that as a result of laser processing the contact angle, surface roughness and surface oxygen content increased whilst the apparent polar and total surface energies decreased. The increase in contact angle and reduction in surface energy components was found to be on account of a mixed intermediate state wetting regime owing to the change in roughness due to the induced topographical patterns. To determine the biomimetic nature of the modified and as-received control samples each one was seeded with 2 x 10 4 cells/ml normal human osteoblast cells and observed after periods of 24 h and 4 days using optical microscopy and SEM to determine mean cell cover densities and variations in cell morphology. In addition, a haemocytometer was used to show that the cell count for the laser patterned samples had increased by up to a factor of 1.5 compared to the as-received control sample after 4 days of incubation. Significantly, it was determined that all laser-induced patterns gave rise to better cell response in comparison to the as-received control sample studied due to increased preferential cell growth on those surfaces with increased surface roughness.

Assessment of metal pollution sources by SEM/EDS analysis of solid particles in snow: a case study of Žerjav, Slovenia.

Science.gov (United States)

Miler, Miloš; Gosar, Mateja

2013-12-01

Solid particles in snow deposits, sampled in mining and Pb-processing area of Žerjav, Slovenia, have been investigated using scanning electron microscopy/energy-dispersive X-ray spectroscopy (SEM/EDS). Identified particles were classified as geogenic-anthropogenic, anthropogenic, and secondary weathering products. Geogenic-anthropogenic particles were represented by scarce Zn- and Pb-bearing ore minerals, originating from mine waste deposit. The most important anthropogenic metal-bearing particles in snow were Pb-, Sb- and Sn-bearing oxides and sulphides. The morphology of these particles showed that they formed at temperatures above their melting points. They were most abundant in snow sampled closest to the Pb-processing plant and least abundant in snow taken farthest from the plant, thus indicating that Pb processing was their predominant source between the last snowfall and the time of sampling. SEM/EDS analysis showed that Sb and Sn contents in these anthropogenic phases were higher and more variable than in natural Pb-bearing ore minerals. The most important secondary weathering products were Pb- and Zn-containing Fe-oxy-hydroxides whose elemental composition and morphology indicated that they mostly resulted from oxidation of metal-bearing sulphides emitted from the Pb-processing plant. This study demonstrated the importance of single particle analysis using SEM/EDS for differentiation between various sources of metals in the environment.

Imaging of Norway spruce early somatic embryos with the ESEM, Cryo-SEM and laser scanning microscope

Czech Academy of Sciences Publication Activity Database

Neděla, Vilém; Hřib, Jiří; Havel, L.; Hudec, Jiří; Runštuk, Jiří

2016-01-01

Roč. 84, May 2016 (2016), s. 67-71 ISSN 0968-4328 R&D Projects: GA ČR(CZ) GA14-22777S Institutional support: RVO:68081731 Keywords : ESEM * Cryo-SEM * bright field/dark field microscopy * extracellular matrix * Picea abies * somatic embryogenesis Subject RIV: JA - Electronics ; Optoelectronics, Electrical Engineering Impact factor: 1.980, year: 2016

Effect of pH on the morphology, mechanical and optical properties of ...

Indian Academy of Sciences (India)

Administrator

Indian Academy of Sciences. 1419. Effect of pH on the morphology, mechanical and optical properties of .... 1 mm and the focal length ( f ) of the convex lens used to focus the laser beam was 300 mm. In the present work,. 20 laser shots ...