Structural perfection of directionally solidified lamellar eutectics

International Nuclear Information System (INIS)

Attallah, T.; Gurzleski, J.E.

1976-01-01

The mechanisms for the formation of faults in lamellar eutectics are reviewed, and it is postulated that faults play several roles in eutectic freezing with their exact importance depending on the specific alloy system and the growth conditions. Faults are not the cause of lamellar spiralling although they are necessary for it to occur. Lamellar spiralling is found to occur only when the crystallographic orientations of the two eutectic phases lead to a growth component normal to the lamellar plane, and although some systems such as Pb-Sn normally spiral it is possible for them to achieve orientation relationships where no spiralling occurs

Collective ratchet effects and reversals for active matter particles on quasi-one-dimensional asymmetric substrates.

Science.gov (United States)

McDermott, Danielle; Olson Reichhardt, Cynthia J; Reichhardt, Charles

2016-10-19

Using computer simulations, we study a two-dimensional system of sterically interacting self-mobile run-and-tumble disk-shaped particles with an underlying periodic quasi-one-dimensional asymmetric substrate, and show that a rich variety of collective active ratchet behaviors arise as a function of particle density, activity, substrate period, and the maximum force exerted by the substrate. The net dc drift, or ratchet transport flux, is nonmonotonic since it increases with increased activity but is diminished by the onset of self-clustering of the active particles. Increasing the particle density decreases the ratchet transport flux for shallow substrates but increases the ratchet transport flux for deep substrates due to collective hopping events. At the highest particle densities, the ratchet motion is destroyed by a self-jamming effect. We show that it is possible to realize reversals of the direction of the net dc drift in the deep substrate limit when multiple rows of active particles can be confined in each substrate minimum, permitting emergent particle-like excitations to appear that experience an inverted effective substrate potential. We map out a phase diagram of the forward and reverse ratchet effects as a function of the particle density, activity, and substrate properties.

Updating the lamellar hypothesis of hippocampal organization

Directory of Open Access Journals (Sweden)

Robert S Sloviter

2012-12-01

Full Text Available In 1971, Andersen and colleagues proposed that excitatory activity in the entorhinal cortex propagates topographically to the dentate gyrus, and on through a trisynaptic circuit lying within transverse hippocampal slices or lamellae [Andersen, Bliss, and Skrede. 1971. Lamellar organization of hippocampal pathways. Exp Brain Res 13, 222-238]. In this way, a relatively simple structure might mediate complex functions in a manner analogous to the way independent piano keys can produce a nearly infinite variety of unique outputs. The lamellar hypothesis derives primary support from the lamellar distribution of dentate granule cell axons (the mossy fibers, which innervate dentate hilar neurons and area CA3 pyramidal cells and interneurons within the confines of a thin transverse hippocampal segment. Following the initial formulation of the lamellar hypothesis, anatomical studies revealed that unlike granule cells, hilar mossy cells, CA3 pyramidal cells, and Layer II entorhinal cells all form axonal projections that are more divergent along the longitudinal axis than the clearly lamellar mossy fiber pathway. The existence of pathways with translamellar distribution patterns has been interpreted, incorrectly in our view, as justifying outright rejection of the lamellar hypothesis [Amaral and Witter. 1989. The three-dimensional organization of the hippocampal formation: a review of anatomical data. Neuroscience 31, 571-591]. We suggest that the functional implications of longitudinally-projecting axons depend not on whether they exist, but on what they do. The observation that focal granule cell layer discharges normally inhibit, rather than excite, distant granule cells suggests that longitudinal axons in the dentate gyrus may mediate "lateral" inhibition and define lamellar function, rather than undermine it. In this review, we attempt a reconsideration of the evidence that most directly impacts the physiological concept of hippocampal lamellar

Spontaneous subconjunctival abscess in congenital lamellar ichthyosis

Directory of Open Access Journals (Sweden)

Shivanand C Bubanale

2018-01-01

Full Text Available Congenital lamellar ichthyosis is an autosomal recessive, heterogeneous disorder presenting at birth with generalized skin involvement. The most common ophthalmic manifestation noted is bilateral ectropion of the lower eyelids. A 1-month-old female neonate, the second born of a nonconsanguineous marriage, presented with 4 days' history of redness, discharge, and swelling in the right eye. There was severe right upper eyelid ectropion, conjunctival injection, chemosis, a subconjunctival mass on the temporal bulbar conjunctiva spontaneously draining pus and corneal haze. The anterior chamber, iris, lens and fundus appeared normal. Congenital lamellar ichthyosis was suspected because of scaling and excessive dryness of the entire body. The occurrence of a spontaneous subconjunctival abscess is not known in lamellar ichthyosis. We thus report the management of a rare case of unilateral upper eyelid ectropion, subconjunctival abscess with orbital cellulitis in congenital lamellar ichthyosis.

Effect of substrates on microstructure and mechanical properties of nano-eutectic 1080 steel produced by aluminothermic reaction

International Nuclear Information System (INIS)

La, Peiqing; Li, Zhengning; Li, Cuiling; Hu, Sulei; Lu, Xuefeng; Wei, Yupeng; Wei, Fuan

2014-01-01

Nano-eutectic bulk 1080 carbon steel was prepared on glass and copper substrates by an aluminothermic reaction casting. The microstructure of the steel was analyzed by an optical microscope, transmission electron microscopy, an electron probe micro-analyzer, a scanning electron microscope and X-ray diffraction. Results show that the microstructure of the steel consisted of a little cementite and lamellar eutectic pearlite. Average lamellar spacing of the pearlite prepared on copper and glass substrates was about 230 nm and 219 nm, respectively. Volume fraction of the pearlite of the two steels was about 95%. Hardness of the steel was about 229 and 270 HV. Tensile strength was about 610 and 641 MPa and tensile elongation was about 15% and 8%. Compressive strength was about 1043 and 1144 MPa. Compared with the steel prepared on copper substrate, the steel prepared on glass substrate had smaller lamellar spacing of the pearlite phase and higher strength, and low ductility due to the smaller spacing. - Highlights: • 1080-carbon steels were successfully prepared by an aluminothermic reaction casting. • Lamellar spacing of the nanoeutetic pearlite is less than 250 nm. • The compressive strength of the steel is about 1144 MPa. • The tensile ductility of the steel is about 15%

AFM measurements of adhesive forces between carbonaceous particles and the substrates

Energy Technology Data Exchange (ETDEWEB)

Zhang, Tianqi [Institute of Nuclear and New Energy Technology of Tsinghua University, Collaborative Innovation Center of Advanced Nuclear Energy Technology, Key Laboratory of Advanced Reactor Engineering and Safety of Ministry of Education, Beijing 100084 (China); Peng, Wei, E-mail: pengwei@tsinghua.edu.cn [Institute of Nuclear and New Energy Technology of Tsinghua University, Collaborative Innovation Center of Advanced Nuclear Energy Technology, Key Laboratory of Advanced Reactor Engineering and Safety of Ministry of Education, Beijing 100084 (China); Shen, Ke [Institute of Nuclear and New Energy Technology of Tsinghua University, Collaborative Innovation Center of Advanced Nuclear Energy Technology, Key Laboratory of Advanced Reactor Engineering and Safety of Ministry of Education, Beijing 100084 (China); Yu, Suyuan, E-mail: suyuan@tsinghua.edu.cn [Center for Combustion Energy, Key Laboratory for Thermal Science and Power Engineering of Ministry of Educations, Department of Thermal Engineering, Tsinghua University, Beijing 100084 (China)

2015-11-15

Highlights: • Adhesive force of spherical carbonaceous particle MCMBs and HTR-10 graphite matrix debris were measured for the first time. • The measured equivalent works of adhesion were much smaller than the ideal values. • The shape factor and the particle morphology reduce the adhesive force. • The adhesion effect does not change directly with the asperity size. - Abstract: Graphite dust is carbonaceous particles generated during operation of High Temperature Gas-Cooled Reactors (HTR). Graphite dust resuspension is the key behavior associated with HTR source term analyses and environmental safety assessment. The adhesive force is the key factor that determines the resuspension rate. The present study used an atomic force microscope (AFM) to measure the adhesive force between a single carbonaceous particle and the substrate. The measurements were performed on mica, graphite IG110 and Inconel 800H. The prepared “probe cantilevers” were mesocarbon microbeads (MCMB), fuel element debris from HTR-10 and graphite NBG18. The equivalent work of adhesion was derived from the measured adhesive force and calculated based on substrate profile approximation and the JKR theoretical model. The measured work was smaller than the ideal work of adhesion, most likely due to the rough particle morphology and the rough substrate surface. Additionally, a shape factor imposes a constraint on the lateral deformation of the particles. Furthermore, surface roughness could reduce the adhesive force some depending on the particle size. Once the particle was too small to be trapped into a trough, the adhesive force would not be further reduced.

AFM measurements of adhesive forces between carbonaceous particles and the substrates

International Nuclear Information System (INIS)

Zhang, Tianqi; Peng, Wei; Shen, Ke; Yu, Suyuan

2015-01-01

Highlights: • Adhesive force of spherical carbonaceous particle MCMBs and HTR-10 graphite matrix debris were measured for the first time. • The measured equivalent works of adhesion were much smaller than the ideal values. • The shape factor and the particle morphology reduce the adhesive force. • The adhesion effect does not change directly with the asperity size. - Abstract: Graphite dust is carbonaceous particles generated during operation of High Temperature Gas-Cooled Reactors (HTR). Graphite dust resuspension is the key behavior associated with HTR source term analyses and environmental safety assessment. The adhesive force is the key factor that determines the resuspension rate. The present study used an atomic force microscope (AFM) to measure the adhesive force between a single carbonaceous particle and the substrate. The measurements were performed on mica, graphite IG110 and Inconel 800H. The prepared “probe cantilevers” were mesocarbon microbeads (MCMB), fuel element debris from HTR-10 and graphite NBG18. The equivalent work of adhesion was derived from the measured adhesive force and calculated based on substrate profile approximation and the JKR theoretical model. The measured work was smaller than the ideal work of adhesion, most likely due to the rough particle morphology and the rough substrate surface. Additionally, a shape factor imposes a constraint on the lateral deformation of the particles. Furthermore, surface roughness could reduce the adhesive force some depending on the particle size. Once the particle was too small to be trapped into a trough, the adhesive force would not be further reduced.

Preparation of textural lamellar tin deposits via electrodeposition

Science.gov (United States)

Wen, Xiaoyu; Pan, Xiaona; Wu, Libin; Li, Ruinan; Wang, Dan; Zhang, Jinqiu; Yang, Peixia

2017-06-01

Lamellar tin deposits were prepared by galvanostatical electroplating from the aqueous acidic-sulfate bath, with gelatin and benzalacetone dissolved in ethanol (ABA+EtOH) as additive, and their morphologies were investigated by scanning electron microscopy. Cathodic polarization curves revealed that the absorbability of ABA+EtOH on the cathode surface was higher than that of gelatin. X-ray diffraction analysis indicated preferred orientations of tin growth led to the formation of lamellar structure and distortion of tin lattice. The growth mechanism of lamellar tin was also discussed.

Oligosaccharides and glycolipids addition in charged lamellar phases

International Nuclear Information System (INIS)

Ricoul, F.

1997-01-01

The aim of this work is to study the addition of oligosaccharides and glycolipids in lamellar phases of the cationic surfactant DDAB (di-dodecyl-dimethyl-ammonium bromide). Two steps have been followed: the determination of phases prisms and the thermodynamic interpretation in terms of molecular interactions. In order to characterize these systems, two new experimental small angle scattering methods have been perfected: 1) a neutron scattering contrast variation method which allows to study the adsorption of aqueous solution in bilayers and 2) a capillary concentration gradient method to establish directly and quantitatively the phases diagrams of ternary systems by X rays scattering. It has been pointed out that the oligosaccharides induce a depletion attractive force on the lamellar-lamellar equilibrium of the DDAB when they are excluded of the most concentrated phase. For the two studied glycolipids: 2-O lauroyl-saccharose and N-lauroyl N-nonyl lactitol, the ternary phase diagrams water-DDAB-glycolipid have been established in terms of temperature. Critical points at ambient temperature have been given. The osmotic pressure in concentrated lamellar phases has been measured. It has been shown that glycolipids increase the hydration repulsion at short distance and that the electrostatic repulsion is outstanding and unchanged at high distance if there is at less 1 mole percent of ionic surfactant. In a dilute solution, glycolipids decrease the maximum swelling of lamellar phases, with a competition between the lamellar phase and the micellae dilute phase for water. (O.M.)

Congenital lamellar ichthyosis, a case report.

OpenAIRE

Joaquín Saavedra D.; María José Sierralta S.; Cristian Saavedra D; Vanesa Rivera C; Francisco Cerda C.

2014-01-01

ABSTRACT INTRODUCTION: Lamellar Ichthyosis is a rare skin diseases belonging to the Group of the so-called genodermatoses. It is a form of congenital ichthyosis evident at birth. CASE REPORT: Male neonate, born at 36 weeks of gestation via cesarian section, appropriate for gestational age and Apgar Score 8. Nonconsanguineous parents. Affected brother with Ichthyosis lamellar. Is hospitalized in the Neonatal Intermediary Care Unit of the Hospital of San Fernando due to ...

Theory of X-ray scattering by strongly distorted aging alloys with lamellar distribution of inclusions

International Nuclear Information System (INIS)

Barabash, R.I.; Krivoglaz, M.A.; AN Ukrainskoj SSR, Kiev. Inst. Metallofiziki)

1981-01-01

The X-ray scattering by strongly distorted heterogeneous alloys containing inclusions of new phase particles is discussed. Two models describing the lamellar structure with various orientation of inclusion axes in different layers are studied. In the first model the dimensions of inclusions are small in comparison with the layer thickness and they are randomly distributed in it, in the second model lamellar inclusions stretch through the whole layer. It is shown that in both models the Debye broadened line intensity distribution consists of overlapping Lorentz curves. A case of inclusions oriented along directions [100] and layers perpendicular to axes [110] is analyzed in detail. The results obtained for this case are compared with experimental results for the Cu-Be alloy

[Indications and surgical approach for lamellar macular holes and pseudoholes].

Science.gov (United States)

Haritoglou, C; Schumann, R G

2017-12-01

This article presents a discussion on the indications for surgical interventions of lamellar macular holes and pseudoholes. What are the criteria for deciding on the surgical intervention for lamellar macular holes and pseudoholes? The article is based on a literature search in PubMed RESULTS: Lamellar macular holes and pseudoholes are subdivided into degenerative and tractive alterations. Both entities are associated with relatively specific morphological and functional criteria, which correlate with the expected functional and morphological results of the surgical intervention. Patients with pseudoholes therefore profit more from a surgical intervention because alterations to the outer retina are less pronounced in these cases. The indications for surgery of lamellar macular holes and pseudoholes are established by the type of lamellar defect and the morphological and functional alterations associated with this condition.

Adsorption of dimeric surfactants in lamellar silicates

Energy Technology Data Exchange (ETDEWEB)

Balcerzak, Mateusz; Pietralik, Zuzanna [Department of Macromolecular Physics, Faculty of Physics, A. Mickiewicz University, Umultowska 85, 61-614 Poznań (Poland); Domka, Ludwik [Department of Metalorganic Chemistry, Faculty of Chemistry, A. Mickiewicz University, Grunwaldzka 6, 60-780 Poznań (Poland); Skrzypczak, Andrzej [Institute of Chemical Technology, Poznań University of Technology, Berdychowo 4, 60-965 Poznań (Poland); Kozak, Maciej, E-mail: mkozak@amu.edu.pl [Department of Macromolecular Physics, Faculty of Physics, A. Mickiewicz University, Umultowska 85, 61-614 Poznań (Poland)

2015-12-01

Highlights: • The intercalation of dimeric surfactants changed the morphology of MMT samples. • XRD indicated structures formed by surfactant molecules in interlayer space. • The four-step thermal decomposition of dimeric surfactant, confirms intercalation. - Abstract: The adsorption of different types of cationic surfactants in lamellar silicates changes their surface character from hydrophilic to hydrophobic. This study was undertaken to obtain lamellar silicates modified by a series of novel dimeric (gemini) surfactants of different length alkyl chains and to characterise these organophilised materials. Synthetic sodium montmorillonite SOMASIF® ME 100 (M) and enriched bentonite of natural origin (Nanoclay – hydrophilic bentonite®) were organophilised with dimeric (gemini) surfactants (1,1′-(1,4-butanediyl)bis(alkoxymethyl)imidazolium dichlorides). As a result of surfactant molecule adsorption in interlamellar space, the d-spacing (d{sub 001}) increased from 0.97 nm (for the anhydrous structure) to 2.04 nm. A Fourier transform infrared spectroscopy (FTIR) analysis of the modified systems reveals bands assigned to the stretching vibrations of the CH{sub 2} and CH{sub 3} groups and the scissoring vibrations of the NH group from the structure of the dimeric surfactants. Thermogravimetric (TG) and derivative thermogravimetric (DTG) studies imply a four-stage process of surfactant decomposition. Scanning electron microscopy (SEM) images provide information on the influence of dimeric surfactant intercalation into the silicate structures. Particles of the modified systems show a tendency toward the formation of irregularly shaped agglomerates.

Construction of highly ordered lamellar nanostructures through Langmuir-Blodgett deposition of molecularly thin titania nanosheets tens of micrometers wide and their excellent dielectric properties.

Science.gov (United States)

Akatsuka, Kosho; Haga, Masa-aki; Ebina, Yasuo; Osada, Minoru; Fukuda, Katsutoshi; Sasaki, Takayoshi

2009-05-26

Exfoliated unilamellar titania nanosheets of Ti(0.87)O(2) with a lateral size of 10-30 microm were deposited layer-by-layer onto various substrates by Langmuir-Blodgett procedure to produce a highly ordered lamellar nanofilms. The nanosheets dispersed in an aqueous suspension containing quaternary ammonium ions as a supporting electrolyte floated spontaneously at the air/liquid interface, and they were successfully transferred onto the substrate after surface compression. Neat tiling of the nanosheets could be realized at an optimized surface pressure. The film thus obtained was exposed to UV light to turn the substrate surface hydrophilic, which was helpful for stable repetition of monolayer deposition. Layer-by-layer growth was confirmed by UV-visible absorption spectra, which showed progressive enhancement of an absorption band due to the nanosheet. Cross-sectional transmission electron microscopy images visualized the ultrathin film homogeneously deposited on the substrate surface and a lamellar fringe of the layer-by-layer assembled nanosheets was clearly resolved at a higher magnification. X-ray diffraction data on the films showed sharp basal reflections up to the seventh order, and Williamson-Hall analysis of the pattern indicated that the film was coherent across the total thickness with respect to X-ray and that the lattice strain was extremely small. In addition, the first basal reflection was accompanied by small satellite peaks, which are accounted for by the Laue interference function. All these features clearly indicate the formation of a highly ordered lamellar nanostructure of the titania nanosheets comparable to artificial lattice films produced via modern vapor-phase deposition processes. The obtained films showed superior dielectric and insulating properties as a reflection of the highly organized film nanoarchitecture.

Synthesis of diamondlike carbon particles in/on a water substrate by laser irradiation

International Nuclear Information System (INIS)

Hidai, Hirofumi; Tokura, Hitoshi

2005-01-01

We proposed two-particle synthesis techniques using a liquid as a substrate. First, utilizing liquid instead of solid substrates, particle synthesis is expected on the liquid surface. Particles sink into the liquid before the particles grow into film, because of liquid fluidity. Second, the excitation of a gas dissolved in water was also attempted. An ArF excimer laser beam was focused in a chamber. The 60% volume of the chamber was filled with water, in which methane was dissolved and the remaining space of the chamber was filled with methane gas. As a result, diamondlike carbon particles could be synthesized in water. The particles synthesized from methane in the gas phase were 50-200 nm in diameter, and the particles synthesized from methane dissolved in water were 200-700 nm in diameter, and no structural differences were observed between the particles of two different diameters. Energy-dispersive spectroscopy, Raman spectroscopy analysis, and high-resolution transmission electron microscopy observations revealed that particles contained a diamondlike carbon component and that graphite was attached to them. These particles were harder than graphite particles

Synthesis and characterization of lamellar aragonite with hydrophobic property

International Nuclear Information System (INIS)

Wang Chengyu; Xu Yang; Liu Yalan; Li Jian

2009-01-01

A novel and simple synthetic method for the preparation of hydrophobic lamellar aragonite has been developed. The crystallization of aragonite was conducted by the reaction of sodium carbonate with calcium chloride in the presence of sodium stearate. The resulting products were characterized by powder X-ray diffraction (XRD), scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR) and the contact angle. The results revealed that sodium stearate plays an important role in determining the structure and morphology of the sample. Besides, we have succeeded in surface modification of particles in situ at the same time. The contact angle of the modified aragonite reached 108.59 deg.

Thermal contact resistance of a particle on a substrate

International Nuclear Information System (INIS)

Tan, J.; Safa, H.; Bonin, B.

1996-01-01

It has been formerly established that field emission in RF cavities is mainly due to contamination by small micron size particles lying on the surface. When applying the RF field, these particles can melt and stick to the surface making it harder to get rid of them. In order to understand the thermal process involved, a crucial physical quantity is needed: the thermal contact resistance between the particle and the substrate. An experimental method is described to measure this quantity, with the use of a scanning electron microscope. By defocusing the beam of the SEM, one can get enough power deposited in one particle to melt it. The power level at which the particle melts gives the thermal contact resistance. Therefore, using the measured value, thermal calculations yield some hints for understanding the violent thermal processes observed in RF fields. (author)

Numerical Study of Suspension HVOF Spray and Particle Behavior Near Flat and Cylindrical Substrates

Science.gov (United States)

Jadidi, M.; Yeganeh, A. Zabihi; Dolatabadi, A.

2018-01-01

In thermal spray processes, it is demonstrated that substrate shape and location have significant effects on particle in-flight behavior and coatings quality. In the present work, the suspension high-velocity oxygen fuel (HVOF) spraying process is modeled using a three-dimensional two-way coupled Eulerian-Lagrangian approach. Flat and cylindrical substrates are placed at different standoff distances, and particles characteristics near the substrates and upon impact are studied. Suspension is a mixture of ethanol, ethylene glycol, and mullite solid powder (3Al2O3·2SiO2) in this study. Suspension droplets with predefined size distribution are injected into the combustion chamber, and the droplet breakup phenomenon is simulated using Taylor analogy breakup model. Furthermore, the eddy dissipation model is used to model the premixed combustion of oxygen-propylene, and non-premixed combustion of oxygen-ethanol and oxygen-ethylene glycol. To simulate the gas phase turbulence, the realizable k-ɛ model is applied. In addition, as soon as the breakup and combustion phenomena are completed, the solid/molten mullite particles are tracked through the domain. It is shown that as the standoff distance increases the particle temperature and velocity decrease and the particle trajectory deviation becomes more significant. The effect of stagnation region on the particle velocity and temperature is also discussed in detail. The catch rate, which is defined as the ratio of the mass of landed particles to injected particles, is calculated for different substrate shapes and standoff distances in this study. The numerical results presented here is consistent with the experimental data in the literature for the same operating conditions.

Thermal contact resistance of a particle on a substrate

International Nuclear Information System (INIS)

Tan, J.; Safa, H.; Bonin, B.

1996-01-01

It has been formerly established that field emission in RF cavities is mainly die to contamination by small micron size particles lying on the surface. When applying the RF field, these particles can melt and stick to the surface making it harder to get rid of them. In order to understand the thermal process involved, a crucial physical quantity is needed: the thermal contact resistance between the particle and the substrate. In the present paper, an experimental method is described to measure this quantity, with the use of a scanning electron microscope. By defocusing the beam of the SEM, one can get enough power deposited in one particle to melt it. The power level at which the particle melts gives the thermal contact resistance. Therefore, using the measured value, thermal calculations yield some hints for understanding the violent thermal processes observed in RF fields. (author)

Synthesis and characterization of a lamellar hydroxyapatite/DNA nanohybrid

Energy Technology Data Exchange (ETDEWEB)

Zuo Guifu; Wan Yizao; Meng Xianguang [School of Materials Science and Engineering, Tianjin University, Tianjin 300072 (China); Zhao Qing [School of Agriculture and Bioengineering, Tianjin University, Tianjin 300072 (China); Ren Kaijing [Department of Joint Surgery, Tianjin Hospital, Tianjin 300211 (China); Jia Shiru [Key Laboratory of Industrial Microbiology, Ministry of Education, Tianjin University of Science and Technology, 29, 13th Street, TEDA, Tianjin 300457 (China); Wang Jiehua, E-mail: gfzuo@tju.edu.cn [School of Agriculture and Bioengineering, Tianjin University, Tianjin 300072 (China)

2011-04-15

Research highlights: {yields} A lamellar hydroxyapatite (HAp)/DNA nanohybrid was prepared as a novel gene delivering vector. {yields} Gel electrophoresis analysis confirmed that the lamellar HAp could protect DNA from degradation of DNase I. {yields} The protected DNA in the HAp/DNA nanohybrid could be recovered readily under acid conditions. - Abstract: Two-dimensional layered materials exhibit desired functionalities when being used as gene delivery materials. In this study, a novel gene delivering vector, lamellar hydroxyapatite (HAp)/DNA nanohybrid was prepared. The structure of HAp/DNA nanohybrid was investigated by X-ray diffraction (XRD), scanning electron microscopy (SEM) and transmission electron microscopy (TEM). Fourier transform infrared (FT-IR) spectroscopy analysis revealed that ion-exchange occurred during the process. Gel electrophoresis analysis confirmed that the lamellar HAp could protect DNA from degradation of DNase I and the protected DNA could be recovered readily under acid conditions. Furthermore, the integrity of released DNA was confirmed by UV-vis spectra.

Synthesis and characterization of a lamellar hydroxyapatite/DNA nanohybrid

International Nuclear Information System (INIS)

Zuo Guifu; Wan Yizao; Meng Xianguang; Zhao Qing; Ren Kaijing; Jia Shiru; Wang Jiehua

2011-01-01

Research highlights: → A lamellar hydroxyapatite (HAp)/DNA nanohybrid was prepared as a novel gene delivering vector. → Gel electrophoresis analysis confirmed that the lamellar HAp could protect DNA from degradation of DNase I. → The protected DNA in the HAp/DNA nanohybrid could be recovered readily under acid conditions. - Abstract: Two-dimensional layered materials exhibit desired functionalities when being used as gene delivery materials. In this study, a novel gene delivering vector, lamellar hydroxyapatite (HAp)/DNA nanohybrid was prepared. The structure of HAp/DNA nanohybrid was investigated by X-ray diffraction (XRD), scanning electron microscopy (SEM) and transmission electron microscopy (TEM). Fourier transform infrared (FT-IR) spectroscopy analysis revealed that ion-exchange occurred during the process. Gel electrophoresis analysis confirmed that the lamellar HAp could protect DNA from degradation of DNase I and the protected DNA could be recovered readily under acid conditions. Furthermore, the integrity of released DNA was confirmed by UV-vis spectra.

Preparation and characterization of molybdenum disilicide coating on molybdenum substrate by air plasma spraying

International Nuclear Information System (INIS)

Wang, Yi; Wang, Dezhi; Yan, Jianhui; Sun, Aokui

2013-01-01

MoSi 2 oxidation protective coatings on molybdenum substrate were prepared by air plasma spraying technique (APS). Microstructure, phase composition, porosity, microhardness and bonding strength of the coatings were investigated and determined. Oxidation behavior of the coating at high temperature was also examined. Results show that composition of the coatings is constituted with MoSi 2 and Mo 5 Si 3 , the surface morphology is described as flattened lamellar features, insufficiently flattened protuberance with some degree of surface roughness, a certain quantity of spherical particles, microcracks and pores. Testing results reveal that microhardness and bonding strength of the coatings increase, and porosity decreases with increasing power or decreasing Ar gas flow rate. Moreover, with decreasing the porosity, the microhardness of the coatings increases. The bonding strength of the coatings also increases with increasing spray distance. The MoSi 2 coated Mo substrate exhibited a good oxidation resistance at 1200 °C.

Formation of precise 2D Au particle arrays via thermally induced dewetting on pre-patterned substrates

Directory of Open Access Journals (Sweden)

Dong Wang

2011-06-01

Full Text Available The fabrication of precise 2D Au nanoparticle arrays over a large area is presented. The technique was based on pre-patterning of the substrate before the deposition of a thin Au film, and the creation of periodic particle arrays by subsequent dewetting induced by annealing. Two types of pre-patterned substrates were used: The first comprised an array of pyramidal pits and the second an array of circular holes. For the dewetting of Au films on the pyramidal pit substrate, the structural curvature-driven diffusion cooperates with capillarity-driven diffusion, resulting in the formation of precise 2D particle arrays for films within a structure dependent thickness-window. For the dewetting of Au films on the circular hole substrate, the periodic discontinuities in the films, induced by the deposition, can limit the diffusion paths and lead to the formation of one particle per individual separated region (holes or mesas between holes, and thus, result in the evolution of precise 2D particle arrays. The influence of the pre-patterned structures and the film thickness is analyzed and discussed. For both types of pre-patterned substrate, the Au film thickness had to be adjusted in a certain thickness-window in order to achieve the precise 2D particle arrays.

Formation of precise 2D Au particle arrays via thermally induced dewetting on pre-patterned substrates

Science.gov (United States)

Ji, Ran

2011-01-01

Summary The fabrication of precise 2D Au nanoparticle arrays over a large area is presented. The technique was based on pre-patterning of the substrate before the deposition of a thin Au film, and the creation of periodic particle arrays by subsequent dewetting induced by annealing. Two types of pre-patterned substrates were used: The first comprised an array of pyramidal pits and the second an array of circular holes. For the dewetting of Au films on the pyramidal pit substrate, the structural curvature-driven diffusion cooperates with capillarity-driven diffusion, resulting in the formation of precise 2D particle arrays for films within a structure dependent thickness-window. For the dewetting of Au films on the circular hole substrate, the periodic discontinuities in the films, induced by the deposition, can limit the diffusion paths and lead to the formation of one particle per individual separated region (holes or mesas between holes), and thus, result in the evolution of precise 2D particle arrays. The influence of the pre-patterned structures and the film thickness is analyzed and discussed. For both types of pre-patterned substrate, the Au film thickness had to be adjusted in a certain thickness-window in order to achieve the precise 2D particle arrays. PMID:21977445

Anatomical and Functional Results of Lamellar Macular Holes Surgery.

Science.gov (United States)

Papadopoulou, D; Donati, G; Mangioris, G; Pournaras, C J

2016-04-01

To determine the long-term surgical findings and outcomes after vitrectomy for symptomatic lamellar macular holes. We studied 28 patients with lamellar macular holes and central visual loss or distortion. All interventions were standard 25 G vitrectomy with membranectomy of the internal limiting membrane (ILM), peeling and gas tamponade with SF6 20 %. Operations were performed by a single experienced surgeon within the last 3 years. Best corrected visual acuity and optical coherence tomography appearance were determined preoperatively and postoperatively. Following the surgical procedure, all macular holes were closed; however, in 3 eyes, significant foveal thinning was associated with changes in the retinal pigment epithelium changes. The mean best-corrected visual acuity improved postoperatively in the majority of the patients (n: 21, mean 0.3 logMAR), stabilised in 4 patients and decreased in 3 patients (mean 0.4 logMAR). Spectral Domain-Optical coherence tomography (SD-OCT) showed resolution of the lamellar lesion and improved macular contour in all cases. We demonstrated improvement in postoperative vision and the anatomical reconstruction of the anatomical contour of the fovea in most eyes with symptomatic lamellar holes. These findings indicate that vitrectomy, membranectomy and ILM peeling with gas tamponade is a beneficial treatment of symptomatic lamellar macular holes. Georg Thieme Verlag KG Stuttgart · New York.

First principles calculations of interstitial and lamellar rhenium nitrides

Energy Technology Data Exchange (ETDEWEB)

Soto, G., E-mail: gerardo@cnyn.unam.mx [Universidad Nacional Autonoma de Mexico, Centro de Nanociencias y Nanotecnologia, Km 107 Carretera Tijuana-Ensenada, Ensenada Baja California (Mexico); Tiznado, H.; Reyes, A.; Cruz, W. de la [Universidad Nacional Autonoma de Mexico, Centro de Nanociencias y Nanotecnologia, Km 107 Carretera Tijuana-Ensenada, Ensenada Baja California (Mexico)

2012-02-15

Highlights: Black-Right-Pointing-Pointer The possible structures of rhenium nitride as a function of composition are analyzed. Black-Right-Pointing-Pointer The alloying energy is favorable for rhenium nitride in lamellar arrangements. Black-Right-Pointing-Pointer The structures produced by magnetron sputtering are metastable variations. Black-Right-Pointing-Pointer The structures produced by high-pressure high-temperature are stable configurations. Black-Right-Pointing-Pointer The lamellar structures are a new category of interstitial dissolutions. - Abstract: We report here a systematic first principles study of two classes of variable-composition rhenium nitride: i, interstitial rhenium nitride as a solid solution and ii, rhenium nitride in lamellar structures. The compounds in class i are cubic and hexagonal close-packed rhenium phases, with nitrogen in the octahedral and tetrahedral interstices of the metal, and they are formed without changes to the structure, except for slight distortions of the unit cells. In the compounds in class ii, by contrast, the nitrogen inclusion provokes stacking faults in the parent metal structure. These faults create trigonal-prismatic sites where the nitrogen residence is energetically favored. This second class of compounds produces lamellar structures, where the nitrogen lamellas are inserted among multiple rhenium layers. The Re{sub 3}N and Re{sub 2}N phases produced recently by high-temperature and high-pressure synthesis belong to this class. The ratio of the nitrogen layers to the rhenium layers is given by the composition. While the first principle calculations point to higher stability for the lamellar structures as opposed to the interstitial phases, the experimental evidence presented here demonstrates that the interstitial classes are synthesizable by plasma methods. We conclude that rhenium nitrides possess polymorphism and that the two-dimensional lamellar structures might represent an emerging class of materials

First principles calculations of interstitial and lamellar rhenium nitrides

International Nuclear Information System (INIS)

Soto, G.; Tiznado, H.; Reyes, A.; Cruz, W. de la

2012-01-01

Highlights: ► The possible structures of rhenium nitride as a function of composition are analyzed. ► The alloying energy is favorable for rhenium nitride in lamellar arrangements. ► The structures produced by magnetron sputtering are metastable variations. ► The structures produced by high-pressure high-temperature are stable configurations. ► The lamellar structures are a new category of interstitial dissolutions. - Abstract: We report here a systematic first principles study of two classes of variable-composition rhenium nitride: i, interstitial rhenium nitride as a solid solution and ii, rhenium nitride in lamellar structures. The compounds in class i are cubic and hexagonal close-packed rhenium phases, with nitrogen in the octahedral and tetrahedral interstices of the metal, and they are formed without changes to the structure, except for slight distortions of the unit cells. In the compounds in class ii, by contrast, the nitrogen inclusion provokes stacking faults in the parent metal structure. These faults create trigonal-prismatic sites where the nitrogen residence is energetically favored. This second class of compounds produces lamellar structures, where the nitrogen lamellas are inserted among multiple rhenium layers. The Re 3 N and Re 2 N phases produced recently by high-temperature and high-pressure synthesis belong to this class. The ratio of the nitrogen layers to the rhenium layers is given by the composition. While the first principle calculations point to higher stability for the lamellar structures as opposed to the interstitial phases, the experimental evidence presented here demonstrates that the interstitial classes are synthesizable by plasma methods. We conclude that rhenium nitrides possess polymorphism and that the two-dimensional lamellar structures might represent an emerging class of materials within binary nitride chemistry.

Mechanisms of lamellar collagen formation in connective tissues.

Science.gov (United States)

Ghazanfari, Samaneh; Khademhosseini, Ali; Smit, Theodoor H

2016-08-01

The objective of tissue engineering is to regenerate functional tissues. Engineering functional tissues requires an understanding of the mechanisms that guide the formation and evolution of structure in the extracellular matrix (ECM). In particular, the three-dimensional (3D) collagen fiber arrangement is important as it is the key structural determinant that provides mechanical integrity and biological function. In this review, we survey the current knowledge on collagen organization mechanisms that can be applied to create well-structured functional lamellar tissues and in particular intervertebral disc and cornea. Thus far, the mechanisms behind the formation of cross-aligned collagen fibers in the lamellar structures is not fully understood. We start with cell-induced collagen alignment and strain-stabilization behavior mechanisms which can explain a single anisotropically aligned collagen fiber layer. These mechanisms may explain why there is anisotropy in a single layer in the first place. However, they cannot explain why a consecutive collagen layer is laid down with an alternating alignment. Therefore, we explored another mechanism, called liquid crystal phasing. While dense concentrations of collagen show such behavior, there is little evidence that the conditions for liquid crystal phasing are actually met in vivo. Instead, lysyl aldehyde-derived collagen cross-links have been found essential for correct lamellar matrix deposition. Furthermore, we suggest that supra-cellular (tissue-level) shear stress may be instrumental in the alignment of collagen fibers. Understanding the potential mechanisms behind the lamellar collagen structure in connective tissues will lead to further improvement of the regeneration strategies of functional complex lamellar tissues. Copyright © 2016 Elsevier Ltd. All rights reserved.

The effect of particle size on the morphology and thermodynamics of diblock copolymer/tethered-particle membranes

International Nuclear Information System (INIS)

Zhang, Bo; Edwards, Brian J.

2015-01-01

A combination of self-consistent field theory and density functional theory was used to examine the effect of particle size on the stable, 3-dimensional equilibrium morphologies formed by diblock copolymers with a tethered nanoparticle attached either between the two blocks or at the end of one of the blocks. Particle size was varied between one and four tenths of the radius of gyration of the diblock polymer chain for neutral particles as well as those either favoring or disfavoring segments of the copolymer blocks. Phase diagrams were constructed and analyzed in terms of thermodynamic diagrams to understand the physics associated with the molecular-level self-assembly processes. Typical morphologies were observed, such as lamellar, spheroidal, cylindrical, gyroidal, and perforated lamellar, with the primary concentration region of the tethered particles being influenced heavily by particle size and tethering location, strength of the particle-segment energetic interactions, chain length, and copolymer radius of gyration. The effect of the simulation box size on the observed morphology and system thermodynamics was also investigated, indicating possible effects of confinement upon the system self-assembly processes

The effect of particle size on the morphology and thermodynamics of diblock copolymer/tethered-particle membranes.

Science.gov (United States)

Zhang, Bo; Edwards, Brian J

2015-06-07

A combination of self-consistent field theory and density functional theory was used to examine the effect of particle size on the stable, 3-dimensional equilibrium morphologies formed by diblock copolymers with a tethered nanoparticle attached either between the two blocks or at the end of one of the blocks. Particle size was varied between one and four tenths of the radius of gyration of the diblock polymer chain for neutral particles as well as those either favoring or disfavoring segments of the copolymer blocks. Phase diagrams were constructed and analyzed in terms of thermodynamic diagrams to understand the physics associated with the molecular-level self-assembly processes. Typical morphologies were observed, such as lamellar, spheroidal, cylindrical, gyroidal, and perforated lamellar, with the primary concentration region of the tethered particles being influenced heavily by particle size and tethering location, strength of the particle-segment energetic interactions, chain length, and copolymer radius of gyration. The effect of the simulation box size on the observed morphology and system thermodynamics was also investigated, indicating possible effects of confinement upon the system self-assembly processes.

Endothelial cell density after deep anterior lamellar keratoplasty (Melles technique)

NARCIS (Netherlands)

Van Dooren, BTH; Mulder, PGH; Nieuwendaal, CP; Beekhuis, WH; Melles, GRJ

PURPOSE: To measure the recipient endothelial cell loss after the Melles technique for deep anterior lamellar keratoplasty. METHODS: In 21 eyes of 21 patients, a deep anterior lamellar keratoplasty procedure was performed. Before surgery and at 6, 12, and 24 months after surgery, specular microscopy

Does lamellar surgery for keratoconus experience the popularity it deserves?

Science.gov (United States)

Wisse, Robert P L; van den Hoven, Célinde M L; Van der Lelij, Allegonda

2014-08-01

To analyse developments in surgical treatment for keratoconus (KC) by assessing rates and types of corneal surgery from 2005 to 2010. The Dutch Transplantation Foundation supplied data on all keratoplasty procedures for KC performed from 2005 to 2010 in the Netherlands. Registration was carried out by the eyebank at allocation and by the surgeon at the time of surgery. The type of surgery was categorized as either a penetrating or a lamellar procedure. Five hundred and seventy-five anonymized records were received, with excellent data completion (99%). Patients undergoing penetrating surgery had on average a lower visual acuity, higher k-readings and were slightly older compared with the lamellar group. A previous corneal hydrops was recorded for 19.1% of patients. Regular penetrating keratoplasty decreased in popularity from 79.7% in 2005 to 43.7% in 2010, due to the increased rate of lamellar surgery (42.5% in 2010) and 'mushroom' penetrating keratoplasty (13.8% in 2010). When hydrops cases were excluded, popularity became equal (47.6% penetrating versus 52.4% lamellar surgery, in 2010). Lamellar surgery is gaining in popularity, although regular penetrating keratoplasty is still the more commonly performed procedure. Only when hydrops cases are excluded do transplant rates become comparable. © 2013 Acta Ophthalmologica Scandinavica Foundation. Published by John Wiley & Sons Ltd.

A Two-Dimensional Lamellar Membrane: MXene Nanosheet Stacks.

Science.gov (United States)

Ding, Li; Wei, Yanying; Wang, Yanjie; Chen, Hongbin; Caro, Jürgen; Wang, Haihui

2017-02-06

Two-dimensional (2D) materials are promising candidates for advanced water purification membranes. A new kind of lamellar membrane is based on a stack of 2D MXene nanosheets. Starting from compact Ti 3 AlC 2 , delaminated nanosheets of the composition Ti 3 C 2 T x with the functional groups T (O, OH, and/or F) can be produced by etching and ultrasonication and stapled on a porous support by vacuum filtration. The MXene membrane supported on anodic aluminum oxide (AAO) substrate shows excellent water permeance (more than 1000 L m -2  h -1  bar -1 ) and favorable rejection rate (over 90 %) for molecules with sizes larger than 2.5 nm. The water permeance through the MXene membrane is much higher than that of the most membranes with similar rejections. Long-time operation also reveals the outstanding stability of the MXene membrane for water purification. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Preparation and characterization of molybdenum disilicide coating on molybdenum substrate by air plasma spraying

Energy Technology Data Exchange (ETDEWEB)

Wang, Yi [Key Laboratory of Ministry of Education for Non-ferrous Materials Science and Engineering, Central South University, Changsha 410083 (China); Key Laboratory of Hunan Province for Metallurgy and Material Processing of Rare Metals, Central South University, Changsha 410083 (China); School of Materials Science and Engineering, Central South University, Changsha 410083 (China); Wang, Dezhi, E-mail: dzwang68@163.com [Key Laboratory of Ministry of Education for Non-ferrous Materials Science and Engineering, Central South University, Changsha 410083 (China); Key Laboratory of Hunan Province for Metallurgy and Material Processing of Rare Metals, Central South University, Changsha 410083 (China); School of Materials Science and Engineering, Central South University, Changsha 410083 (China); Yan, Jianhui [Advanced Materials Synthesis and Application Technology Laboratory, Hunan University of Science and Technology, Xiangtan 411201 (China); Sun, Aokui [Key Laboratory of Ministry of Education for Non-ferrous Materials Science and Engineering, Central South University, Changsha 410083 (China); Key Laboratory of Hunan Province for Metallurgy and Material Processing of Rare Metals, Central South University, Changsha 410083 (China); School of Materials Science and Engineering, Central South University, Changsha 410083 (China)

2013-11-01

MoSi{sub 2} oxidation protective coatings on molybdenum substrate were prepared by air plasma spraying technique (APS). Microstructure, phase composition, porosity, microhardness and bonding strength of the coatings were investigated and determined. Oxidation behavior of the coating at high temperature was also examined. Results show that composition of the coatings is constituted with MoSi{sub 2} and Mo{sub 5}Si{sub 3}, the surface morphology is described as flattened lamellar features, insufficiently flattened protuberance with some degree of surface roughness, a certain quantity of spherical particles, microcracks and pores. Testing results reveal that microhardness and bonding strength of the coatings increase, and porosity decreases with increasing power or decreasing Ar gas flow rate. Moreover, with decreasing the porosity, the microhardness of the coatings increases. The bonding strength of the coatings also increases with increasing spray distance. The MoSi{sub 2} coated Mo substrate exhibited a good oxidation resistance at 1200 °C.

Endothelial cell density after deep anterior lamellar keratoplasty (Melles technique)

NARCIS (Netherlands)

van Dooren, Bart T. H.; Mulder, Paul G. H.; Nieuwendaal, Carla P.; Beekhuis, W. Houdijn; Melles, Gerrit R. J.

2004-01-01

To measure the recipient endothelial cell loss after the Melles technique for deep anterior lamellar keratoplasty. In 21 eyes of 21 patients, a deep anterior lamellar keratoplasty procedure was performed. Before surgery and at 6, 12, and 24 months after surgery, specular microscopy was performed to

Precipitation kinetics of lamellar (γ) laths in a TiAl-base alloy

International Nuclear Information System (INIS)

Zhang, W.J.; Francesconi, L.; Evangelista, E.

1997-01-01

Titanium aluminide is a candidate material for high temperature applications. Although different types of microstructure have been produced in TiAl-base alloys, the fully-lamellar structure is currently regarded as the most attractive. This kind of microstructure can be characterized by the factors, namely, colony size, lamellar interspacing, the existence of Widmanstatten (secondary) laths, and the type of grain boundaries (smooth or interlocking). The objective of this paper is to examine the nucleation and growth kinetics of γ lamellar laths during continuous and isothermal cooling. These data are expected to benefit the understanding of the transformation mechanism and the design of lamellar TiAl microstructure for industrial application

En face spectral domain optical coherence tomography analysis of lamellar macular holes.

Science.gov (United States)

Clamp, Michael F; Wilkes, Geoff; Leis, Laura S; McDonald, H Richard; Johnson, Robert N; Jumper, J Michael; Fu, Arthur D; Cunningham, Emmett T; Stewart, Paul J; Haug, Sara J; Lujan, Brandon J

2014-07-01

To analyze the anatomical characteristics of lamellar macular holes using cross-sectional and en face spectral domain optical coherence tomography. Forty-two lamellar macular holes were retrospectively identified for analysis. The location, cross-sectional length, and area of lamellar holes were measured using B-scans and en face imaging. The presence of photoreceptor inner segment/outer segment disruption and the presence or absence of epiretinal membrane formation were recorded. Forty-two lamellar macular holes were identified. Intraretinal splitting occurred within the outer plexiform layer in 97.6% of eyes. The area of intraretinal splitting in lamellar holes did not correlate with visual acuity. Eyes with inner segment/outer segment disruption had significantly worse mean logMAR visual acuity (0.363 ± 0.169; Snellen = 20/46) than in eyes without inner segment/outer segment disruption (0.203 ± 0.124; Snellen = 20/32) (analysis of variance, P = 0.004). Epiretinal membrane was present in 34 of 42 eyes (81.0%). En face imaging allowed for consistent detection and quantification of intraretinal splitting within the outer plexiform layer in patients with lamellar macular holes, supporting the notion that an area of anatomical weakness exists within Henle's fiber layer, presumably at the synaptic connection of these fibers within the outer plexiform layer. However, the en face area of intraretinal splitting did not correlate with visual acuity, disruption of the inner segment/outer segment junction was associated with significantly worse visual acuity in patients with lamellar macular holes.

Laser thermokeratoplasty after lamellar corneal cutting.

Science.gov (United States)

Ismail, M M; Pérez-Santonja, J J; Alió, J L

1999-02-01

To evaluate the effect of laser thermokeratoplasty (LTK) in eyes that previously had a lamellar corneal cut. University of Al-Azhar, Cairo, Egypt, and Instituto Oftalmológico de Alicante, Spain. In 15 eyes (10 patients), noncontact LTK was applied 6 to 8 weeks after a lamellar corneal cut had been made. Central pachymetry, keratometry, and videokeratography were performed and uncorrected visual acuity, best spectacle-corrected visual acuity (BSCVA), and manifest and cycloplegic refractions measured before and 1, 6, 12, and 18 months after LTK. Mean follow-up was 19.13 months. Mean refraction was +5.93 diopters (D) +/- 1.9 (SD) before LTK and -0.43 +/- 1.5 D at 1 month, +1.63 +/- 1.6 D at 6 months, 1.91 +/- 1.41 at 12 months, and +2.01 +/- 1.5 D at the end of the study. Total regression did not occur in any case. Mean BSCVA before LTK was 0.66 +/- 0.2, and spontaneous visual acuity at the end of the study was 0.58 +/- 0.18. No patient lost any lines of preoperative BSCVA. There was no significant difference between the results at 12 months and at the end of the study. Corneal lamellar cutting appeared to improve the magnitude of the refractive effect of noncontact LTK and to decrease the amount of regression.

CST simulations of THz Smith–Purcell radiation from a lamellar grating with vacuum gaps

International Nuclear Information System (INIS)

Lekomtsev, K.; Karataev, P.; Tishchenko, A.A.; Urakawa, J.

2015-01-01

Smith–Purcell radiation (SPR) from a lamellar grating with vacuum gaps was calculated using Computer Simulation Technology (CST) Particle In Cell (PIC) solver. The shapes of the radiation distributions were compared with those of Resonant Diffraction Radiation theory. Study of calculation domain meshing was performed. Influence of a transverse bunch size on the calculation accuracy and an SPR intensity distribution was investigated. Dependencies of the SPR yield on Lorentz factor and grating strip depth were calculated and compared with previously reported theoretical and experimental studies

Barriers to defect melting in chemo-epitaxial directed self-assembly of lamellar-forming diblock copolymer/homopolymer blends

Science.gov (United States)

Izumi, Kenichi; Kim, Bongkeun; Laachi, Nabil; Delaney, Kris T.; Carilli, Michael; Fredrickson, Glenn H.

2015-03-01

We investigate energy barriers and minimum energy paths (MEPs) for transitions from dislocation-pair defects to perfect lamellae in self-assembly of AB-diblock copolymer plus A- or B-homopolymer blends using self-consistent field theory (SCFT) and the numerical string method. For neutral substrates, all minimum energy paths discovered by the string method show two successive energy barriers. The two-barrier qualitative nature of the MEPs appears not to depend on the presence or absence of small amounts of homopolymer. For the first energy barrier, the barrier height shows pronounced increase with addition of A-homopolymer due to localization of A-homopolymer on the T-junction core of the dislocation. For chemo-epitaxially patterned substrates (stripes of A-attractive substrate alternating with neutral substrate), the presence of A-attractive stripes helps draw the system towards a perfect lamellar configuration, and energy barriers along the MEP are reduced, in some cases disappearing entirely. Our findings provide guidance on how the presence of homopolymer and chemo-epitaxial prepatterns affect the stability of defective morphologies.

Formation of Lamellar Structured Oxide Dispersion Strengthening Layers in Zircaloy-4

Energy Technology Data Exchange (ETDEWEB)

Jung, Yang-Il; Park, Jung-Hwan; Park, Dong-Jun; Kim, Hyun-Gil; Yang, Jae-Ho; Koo, Yang-Hyun [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of); Lim, Yoon-Soo [Hanbat National University, Daejeon (Korea, Republic of)

2016-10-15

Korea Atomic Energy Research Institute (KAERI) is one of the leading organizations for developing ATF claddings. One concept is to form an oxidation-resistant layer on Zr cladding surface. The other is to increase high-temperature mechanical strength of Zr tube. The oxide dispersion strengthened (ODS) zirconium was proposed to increase the strength of the Zr-based alloy up to high temperatures. According to our previous investigations, the tensile strength of Zircaloy-4 was increased by up to 20% with the formation of a thin dispersed oxide layer with a thickness less than 10% of that of the Zircaloy-4 substrate. However, the tensile elongation of the samples decreased drastically. The brittle fracture was a major concern in development of the ODS Zircaloy-4. In this study, a lamellar structure of ODS layer was formed to increase ductility of the ODS Zircaloy-4. The mechanical properties were varied depending on the structure of ODS layer. For example, the partial formation of ODS layer with the thickness of 10% to the substrate thickness induced the increase in tensile strength up to about 20% than fresh Zircaloy-4.

Flux flow and proximity effects in aligned Pb--Cd eutectic lamellar structures

International Nuclear Information System (INIS)

Spencer, C.R.

1977-09-01

A high speed directional solidification technique was used to fabricate lamellar Pb-Cd and (Pb-Mg)--(Cd-Mg) superconductor-normal metal composites in which all the lamellae are oriented perpendicular to the broad surface of the sample. These lamellar composites are found to behave like a large number (approximately 1000) of superconducting-normal-superconducting junctions. For the Pb-Cd eutectic system, the critical current densities and critical fields have shown no dependence upon the lamellar periods between 1.0 and 3.1 microns. The critical current density of the aligned lamellar Pb-Cd structures was enhanced approximately 50% when compared to quenched eutectic alloy and to pure Pb. The superconducting transition temperature, T/sub c/, varies inversely with the square of the thickness of the superconducting material as expected from Ginzburg-Landau theory. Upon annealing, the Pb lamellae change from type II to type I superconductivity

Flux flow and proximity effects in aligned Pb--Cd eutectic lamellar structures

Energy Technology Data Exchange (ETDEWEB)

Spencer, C. R.

1977-09-01

A high speed directional solidification technique was used to fabricate lamellar Pb-Cd and (Pb-Mg)--(Cd-Mg) superconductor-normal metal composites in which all the lamellae are oriented perpendicular to the broad surface of the sample. These lamellar composites are found to behave like a large number (approximately 1000) of superconducting-normal-superconducting junctions. For the Pb-Cd eutectic system, the critical current densities and critical fields have shown no dependence upon the lamellar periods between 1.0 and 3.1 microns. The critical current density of the aligned lamellar Pb-Cd structures was enhanced approximately 50% when compared to quenched eutectic alloy and to pure Pb. The superconducting transition temperature, T/sub c/, varies inversely with the square of the thickness of the superconducting material as expected from Ginzburg-Landau theory. Upon annealing, the Pb lamellae change from type II to type I superconductivity.

Enhanced printability of thermoplastic polyurethane substrates by silica particles surface interactions

Energy Technology Data Exchange (ETDEWEB)

Cruz, S., E-mail: s.cruz@dep.uminho.pt [IPC/I3N – Institute of Polymers and Composites/Inst. of Nanostructures, Nanomodelling and Nanofabrication, Department Polymer Engineering, University of Minho, 4804-533 Guimarães (Portugal); Rocha, L.A. [CMEMS, University of Minho, 4804-533 Guimarães (Portugal); Viana, J.C. [IPC/I3N – Institute of Polymers and Composites/Inst. of Nanostructures, Nanomodelling and Nanofabrication, Department Polymer Engineering, University of Minho, 4804-533 Guimarães (Portugal)

2016-01-01

Graphical abstract: - Highlights: • A new method development for surface treatment of thermoplastic polyurethane (TPU) substrates. • The proposed method increases TPU surface energy (by 45%) and consequently the TPU wettability. • Great increase of the TPU surface roughness (by 621%). • Inkjet printed conductive ink was applied to the surface treated TPU substrate and significant improvements on the printability were obtained. - Abstract: A new method developed for the surface treatment of thermoplastic polymer substrates that increases their surface energies is introduced in this paper. The method is environmental friendly and low cost. In the proposed surface treatment method, nanoparticles are spread over the thermoplastic polyurethane (TPU) flexible substrate surface and then thermally fixed. This latter step allows the nanoparticles sinking-in on the polymer surface, resulting in a higher polymer–particle interaction at their interfacial region. The addition of nanoparticles onto the polymer surface increases surface roughness. The extent of the nanoparticles dispersion and sink-in in the substrate was evaluated through microscopy analysis (SEM). The roughness of the surface treated polymeric substrate was evaluated by AFM analysis. Substrate critical surface tension (ST) was measured by contact angle. In general, a homogeneous roughness form is achieved to a certain level. Great increase of the TPU surface roughness (by 621%) was induced by the propose method. The proposed surface treatment method increased significantly the substrate ST (by 45%) and consequently the TPU wettability. This novel surface treatment of thermoplastic polymers was applied to the inkjet printing of TPU substrates with conductive inks, and significant improvements on the printability were obtained.

Mechanical properties of crossed-lamellar structures in biological shells: A review.

Science.gov (United States)

Li, X W; Ji, H M; Yang, W; Zhang, G P; Chen, D L

2017-10-01

The self-fabrication of materials in nature offers an alternate and powerful solution towards the grand challenge of designing advanced structural materials, where strength and toughness are always mutually exclusive. Crossed-lamellar structures are the most common microstructures in mollusks that are composed of aragonites and a small amount of organic materials. Such a distinctive composite structure has a fracture toughness being much higher than that of pure carbonate mineral. These structures exhibiting complex hierarchical microarchitectures that span several sub-level lamellae from microscale down to nanoscale, can be grouped into two types, i.e., platelet-like and fiber-like crossed-lamellar structures based on the shapes of basic building blocks. It has been demonstrated that these structures have a great potential to strengthen themselves during deformation. The observed underlying toughening mechanisms include microcracking, channel cracking, interlocking, uncracked-ligament bridging, aragonite fiber bridging, crack deflection and zig-zag, etc., which play vital roles in enhancing the fracture resistance of shells with the crossed-lamellar structures. The exploration and utilization of these important toughening mechanisms have attracted keen interests of materials scientists since they pave the way for the development of bio-inspired advanced composite materials for load-bearing structural applications. This article is aimed to review the characteristics of hierarchical structures and the mechanical properties of two kinds of crossed-lamellar structures, and further summarize the latest advances and biomimetic applications based on the unique crossed-lamellar structures. Copyright © 2017 Elsevier Ltd. All rights reserved.

HCP to FCT + precipitate transformations in lamellar gamma-titanium aluminide alloys

Science.gov (United States)

Karadge, Mallikarjun Baburao

Fully lamellar gamma-TiAl [alpha2(HCP) + gamma(FCT)] based alloys are potential structural materials for aerospace engine applications. Lamellar structure stabilization and additional strengthening mechanisms are major issues in the ongoing development of titanium aluminides due to the microstructural instability resulting from decomposition of the strengthening alpha 2 phase. This work addresses characterization of multi-component TiAl systems to identify the mechanism of lamellar structure refinement and assess the effects of light element additions (C and Si) on creep deformation behavior. Transmission electron microscopy studies directly confirmed for the first time that, fine lamellar structure is formed by the nucleation and growth of a large number of basal stacking faults on the 1/6 dislocations cross slipping repeatedly into and out of basal planes. This lamellar structure can be tailored by modifying jog heights through chemistry and thermal processing. alpha 2 → gamma transformation during heating (investigated by differential scanning calorimetry and X-ray diffraction) is a two step process involving the formation of a novel disordered FCC gamma' TiAl [with a(gamma') = c(gamma)] as an intermediate phase followed by ordering. Addition of carbon and silicon induced Ti2AlC H-type carbide precipitation inside the alpha2 lath and Ti 5(Al,Si)3 zeta-type silicide precipitation at the alpha 2/gamma interface. The H-carbides preserve alpha2/gamma type interfaces, while zeta-silicide precipitates restrict ledge growth and interfacial sliding enabling strong resistance to creep deformation.

Thermodynamic and structural study of two-dimensional phase transitions and orientational order in films of linear molecules with a large quadrupole moment, physi-sorbed on lamellar substrates

International Nuclear Information System (INIS)

Terlain, Anne

1984-01-01

The 2D (two-dimensional) phase transitions and orientational order in N 2 O, CO 2 , C 2 N 2 and C 2 D 2 films physi-sorbed on the (0001) face of graphite or lamellar halides, were studied experimentally by adsorption isotherm measurements and neutron diffraction. The thermodynamic functions derived from sets of isotherms suggest that crystal monolayers of N 2 O, CO 2 , and C 2 N 2 adsorbed on graphite are orientationally ordered and that the quadrupolar interaction stabilizes the 2D crystal with respect to the 2D liquid. This stabilization leads to an increase in the 2D triple point temperature, T 2t as compared with the 2D critical temperature T 2c . For C 2 N 2 this stabilization is so pronounced that T 2t becomes virtually higher than T 2c , and the phase diagram qualitatively different, having no gas-liquid coexistence domain. From a neutron diffraction experiment we have determined the crystal structure of the C 2 N 2 monolayer. It supports our interpretation of the monolayer phase diagram. In N 2 O, CO 2 , C 2 N 2 films adsorbed on graphite the molecules lie flat on the surface and their orientational order hence differs from that in the bulk crystals resulting in a loss of adsorbate-adsorbate interaction energy. Beyond a given film thickness this loss will not be compensated by the adsorbate-substrate interaction and the film will stop growing. For most of the films studied a partial wetting transition is observed at which the film thickness increases discontinuously with temperature. Although C 2 N 2 and C 2 D 2 monolayers on graphite have comparable adsorption energies, only C 2 D 2 is adsorbed on lamellar halides. This adsorption is possible only because the monolayer has a large entropy due to orientational disorder. For C 2 N 2 , which has a higher moment of inertia, such an orientational disorder cannot exist. (author) [fr

Solvothermal Vapor Annealing of Lamellar Poly(styrene)-block-poly(d,l-lactide) Block Copolymer Thin Films for Directed Self-Assembly Application.

Science.gov (United States)

Cummins, Cian; Mokarian-Tabari, Parvaneh; Andreazza, Pascal; Sinturel, Christophe; Morris, Michael A

2016-03-01

Solvothermal vapor annealing (STVA) was employed to induce microphase separation in a lamellar forming block copolymer (BCP) thin film containing a readily degradable block. Directed self-assembly of poly(styrene)-block-poly(d,l-lactide) (PS-b-PLA) BCP films using topographically patterned silicon nitride was demonstrated with alignment over macroscopic areas. Interestingly, we observed lamellar patterns aligned parallel as well as perpendicular (perpendicular microdomains to substrate in both cases) to the topography of the graphoepitaxial guiding patterns. PS-b-PLA BCP microphase separated with a high degree of order in an atmosphere of tetrahydrofuran (THF) at an elevated vapor pressure (at approximately 40-60 °C). Grazing incidence small-angle X-ray scattering (GISAXS) measurements of PS-b-PLA films reveal the through-film uniformity of perpendicular microdomains after STVA. Perpendicular lamellar orientation was observed on both hydrophilic and relatively hydrophobic surfaces with a domain spacing (L0) of ∼32.5 nm. The rapid removal of the PLA microdomains is demonstrated using a mild basic solution for the development of a well-defined PS mask template. GISAXS data reveal the through-film uniformity is retained following wet etching. The experimental results in this article demonstrate highly oriented PS-b-PLA microdomains after a short annealing period and facile PLA removal to form porous on-chip etch masks for nanolithography application.

Fabrication of micropillar substrates using replicas of alpha-particle irradiated and chemically etched PADC films

International Nuclear Information System (INIS)

Ng, C.K.M.; Chong, E.Y.W.; Roy, V.A.L.; Cheung, K.M.C.; Yeung, K.W.K.; Yu, K.N.

2012-01-01

We proposed a simple method to fabricate micropillar substrates. Polyallyldiglycol carbonate (PADC) films were irradiated by alpha particles and then chemically etched to form a cast with micron-scale spherical pores. A polydimethylsiloxane (PDMS) replica of this PADC film gave a micropillar substrate with micron-scale spherical pillars. HeLa cells cultured on such a micropillar substrate had significantly larger percentage of cells entering S-phase, attached cell numbers and cell spreading areas. - Highlights: ► We proposed a simple method to fabricate micropillar substrates. ► Polyallyldiglycol carbonate films were irradiated and etched to form casts. ► Polydimethylsiloxane replica then formed the micropillar substrates. ► Attachment and proliferation of HeLa cells were enhanced on these substrates.

Synergistic effects of semiconductor substrate and noble metal nano-particles on SERS effect both theoretical and experimental aspects

Science.gov (United States)

Yang, Chen; Liang, Pei; Tang, Lisha; Zhou, Yongfeng; Cao, Yanting; Wu, Yanxiong; Zhang, De; Dong, Qianmin; Huang, Jie; He, Peng

2018-04-01

As a means of chemical identification and analysis, Surface enhanced Raman spectroscopy (SERS), with the advantages of high sensitivity and selectivity, non-destructive, high repeatability and in situ detection etc., has important significance in the field of composition detection, environmental science, biological medicine etc. Physical model of coupling effect between different semiconductor substrates and noble metal particles were investigated by using 3D-FDTD method. Mechanism and the effects of excitation wavelength, particle spacing and semiconductor substrate types on the SERS effect were discussed. The results showed that the optimal excitation wavelengths of three noble metals of Ag, Au, Cu, were located at 510, 600 and 630 nm, respectively; SERS effect of Ag, Au, Cu increases with the decreasing of the inter distance of particles, while the distance of the NPs reaches the critical value of 3 nm, the strength of SERS effect will be greatly enhanced. For the four different types of substrate of Ge, Si, SiO2 (glass) and Al2O3, the SERS effect of Ag on SiO2 > Ge > Al2O3 > Si. For Au and Cu nanoparticles, the SERS effect of them on oxide substrate is stronger than that on non-oxide substrate. In order to verify FDTD simulations, taking silver nanoparticles as an example, and silver nanoparticles prepared by chemical method were spinning coating on the four different substrates with R6G as probe molecules. The results show that the experimental results are consistent with FDTD theoretical simulations, and the SERS enhancement effect of Ag-SiO2 substrate is best. The results of this study have important theoretical significance to explain the variations of SERS enhancement on different noble metals, which is also an important guide for the preparation of SERS substrates, especially for the microfluidics. The better Raman effect can be realized by choosing proper substrate type, particle spacing and excitation wavelength, result in expanding the depth and width

Fabrication of micropillar substrates using replicas of alpha-particle irradiated and chemically etched PADC films

Energy Technology Data Exchange (ETDEWEB)

Ng, C.K.M. [Department of Physics and Materials Science, City University of Hong Kong, Tat Chee Avenue, Kowloon Tong (Hong Kong); Chong, E.Y.W. [Department of Orthopaedics and Traumatology, University of Hong Kong (Hong Kong); Roy, V.A.L. [Department of Physics and Materials Science, City University of Hong Kong, Tat Chee Avenue, Kowloon Tong (Hong Kong); Cheung, K.M.C.; Yeung, K.W.K. [Department of Orthopaedics and Traumatology, University of Hong Kong (Hong Kong); Yu, K.N., E-mail: appetery@cityu.edu.hk [Department of Physics and Materials Science, City University of Hong Kong, Tat Chee Avenue, Kowloon Tong (Hong Kong)

2012-07-15

We proposed a simple method to fabricate micropillar substrates. Polyallyldiglycol carbonate (PADC) films were irradiated by alpha particles and then chemically etched to form a cast with micron-scale spherical pores. A polydimethylsiloxane (PDMS) replica of this PADC film gave a micropillar substrate with micron-scale spherical pillars. HeLa cells cultured on such a micropillar substrate had significantly larger percentage of cells entering S-phase, attached cell numbers and cell spreading areas. - Highlights: Black-Right-Pointing-Pointer We proposed a simple method to fabricate micropillar substrates. Black-Right-Pointing-Pointer Polyallyldiglycol carbonate films were irradiated and etched to form casts. Black-Right-Pointing-Pointer Polydimethylsiloxane replica then formed the micropillar substrates. Black-Right-Pointing-Pointer Attachment and proliferation of HeLa cells were enhanced on these substrates.

Analysis of Lamellar Structures with Application of Generalized Functions

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Kipiani Gela

2016-12-01

Full Text Available Theory of differential equations in respect of the functional area is based on the basic concepts on generalized functions and splines. There are some basic concepts related to the theory of generalized functions and their properties are considered in relation to the rod systems and lamellar structures. The application of generalized functions gives the possibility to effectively calculate step-variable stiffness lamellar structures. There are also widely applied structures, in that several in which a number of parallel load bearing layers are interconnected by discrete-elastic links. For analysis of system under study, such as design diagrams, there are applied discrete and discrete-continual models.

Magnetic properties of lamellar tetrataenite in Toluca iron meteorite

International Nuclear Information System (INIS)

Funaki, Minoru; Nagata, Takesi; Danon, J.

1985-01-01

Magnetic studies were conducted using lamellar tetrataenite extracted from the Toluca octahedrite by a diluted HCl etching technique. Natural remanent magnetization (NRM) in the lamellae is very stable against AF demagnetization and is quite intense, ranging from 2.58 to 37.42 x10 -2 emu/g. This NRM is completely demagnetized thermally at about 550 0 C. The most characteristic change in magnetic properties on heating to about 550 C 0 is a significant decrease in magnetic coercivity. This observation is consistent with the results obtained from chondrites. The paramagnetic component in lamellar tetrataenite, which is estimated by Moessbauer spectrum analyses, was not detected by conventional magnetic studies. (Author) [pt

Strengthening behavior of beta phase in lamellar microstructure of TiAl alloys

Science.gov (United States)

Zhu, Hanliang; Seo, D. Y.; Maruyama, K.

2010-01-01

β phase can be introduced to TiAl alloys by the additions of β stabilizing elements such as Cr, Nb, W, and Mo. The β phase has a body-centered cubic lattice structure and is softer than the α2 and γ phases in TiAl alloys at elevated temperatures, and hence is thought to have a detrimental effect on creep strength. However, fine β precipitates can be formed at lamellar interfaces by proper heat treatment conditions and the β interfacial precipitate improves the creep resistance of fully lamellar TiAl alloys, since the phase interface of γ/β retards the motion of dislocations during creep. This paper reviews recent research on high-temperature strengthening behavior of the β phase in fully lamellar TiAl alloys.

Quantitative analysis of lamellar bodies in amniotic fluid as fetal pulmonary maturity indicator

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Ljubić Vesna

2009-01-01

Full Text Available Background/Aim. Although lamellar bodies have been the center of interest over the last years, the published results of fetal pulmonary maturity determination according to their concentration in amniotic fluid are controversial. The aim of this study was to determine the significance of lamellar bodies, as well as the ratio lecithin/sphingomyelin (L/S in amniotic fluid for the assessment of fetal pulmonary maturity. Methods. This prospective 2-year study included 102 female examinees, ranging from 17 to 44 years of age, in whom lamellar bodies concentrations in amniotic fluid were determined to check the efficacy of the applied therapy for obtaining arteficial fetal pulmonary maturity. The shake test was applied as a comparative test for determining a quantitative L/S ratio. To determine a fetus maturity and development stage we followed up biparietal diameter, abdominal circumference, femure length, ponderal index at birth and body mass. Results. Out of a total of 102 amniocenteses within a period from 26th to 40th gestation week only 70 results were considered due to 32 unknown neonatal outcomes. Biparietal diameter was 224-362 mm, femur length 56 - 78 mm, ponderal index 1.22-2.84, fetus body mass 1300- 4 350 g. There was found a significant relation between gestation age and lamellar bodies concentration (R = 0.396398, p < 0.01, as well as between gestation age and the ratio L/S (R = 0.691297, p < 0.01. Also, there was a significant correlation of lamellar bodies concentration to the ratio L/S determined (R = 0.493609, p < 0.01. Conclusion. Determination of lamellar bodies concentration values is a reliable method to confirm fetal pulmonary maturity.

Synergistic structures from magnetic freeze casting with surface magnetized alumina particles and platelets.

Science.gov (United States)

Frank, Michael B; Hei Siu, Sze; Karandikar, Keyur; Liu, Chin-Hung; Naleway, Steven E; Porter, Michael M; Graeve, Olivia A; McKittrick, Joanna

2017-12-01

Magnetic freeze casting utilizes the freezing of water, a low magnetic field and surface magnetized materials to make multi-axis strengthened porous scaffolds. A much greater magnetic moment was measured for larger magnetized alumina platelets compared with smaller particles, which indicated that more platelet aggregation occurred within slurries. This led to more lamellar wall alignment along the magnetic field direction during magnetic freeze casting at 75 mT. Slurries with varying ratios of magnetized particles to platelets (0:1, 1:3, 1:1, 3:1, 7:1, 1:0) produced porous scaffolds with different structural features and degrees of lamellar wall alignment. The greatest mechanical enhancement in the magnetic field direction was identified in the synergistic condition with the highest particle to platelet ratio (7:1). Magnetic freeze casting with varying ratios of magnetized anisotropic and isotropic alumina provided insights about how heterogeneous morphologies aggregate within lamellar walls that impact mechanical properties. Fabrication of strengthened scaffolds with multi-axis aligned porosity was achieved without introducing different solid materials, freezing agents or additives. Resemblance of 7:1 particle to platelet scaffold microstructure to wood light-frame house construction is framed in the context of assembly inspiration being derived from both natural and synthetic sources. Copyright © 2017 Elsevier Ltd. All rights reserved.

Modeling creep deformation of a two-phase TiAI/Ti3Al alloy with a lamellar microstructure

Science.gov (United States)

Bartholomeusz, Michael F.; Wert, John A.

1994-10-01

A two-phase TiAl/Ti3Al alloy with a lamellar microstructure has been previously shown to exhibit a lower minimum creep rate than the minimum creep rates of the constituent TiAl and Ti3Al single-phase alloys. Fiducial-line experiments described in the present article demonstrate that the creep rates of the constituent phases within the two-phase TiAl/Ti3Al lamellar alloy tested in compression are more than an order of magnitude lower than the creep rates of single-phase TiAl and Ti3Al alloys tested in compression at the same stress and temperature. Additionally, the fiducial-line experiments show that no interfacial sliding of the phases in the TiAl/Ti3Al lamellar alloy occurs during creep. The lower creep rate of the lamellar alloy is attributed to enhanced hardening of the constituent phases within the lamellar microstructure. A composite-strength model has been formulated to predict the creep rate of the lamellar alloy, taking into account the lower creep rates of the constituent phases within the lamellar micro-structure. Application of the model yields a very good correlation between predicted and experimentally observed minimum creep rates over moderate stress and temperature ranges.

Structural basis for substrate placement by an archaeal box C/D ribonucleoprotein particle.

Science.gov (United States)

Xue, Song; Wang, Ruiying; Yang, Fangping; Terns, Rebecca M; Terns, Michael P; Zhang, Xinxin; Maxwell, E Stuart; Li, Hong

2010-09-24

Box C/D small nucleolar and Cajal body ribonucleoprotein particles (sno/scaRNPs) direct site-specific 2'-O-methylation of ribosomal and spliceosomal RNAs and are critical for gene expression. Here we report crystal structures of an archaeal box C/D RNP containing three core proteins (fibrillarin, Nop56/58, and L7Ae) and a half-mer box C/D guide RNA paired with a substrate RNA. The structure reveals a guide-substrate RNA duplex orientation imposed by a composite protein surface and the conserved GAEK motif of Nop56/58. Molecular modeling supports a dual C/D RNP structure that closely mimics that recently visualized by electron microscopy. The substrate-bound dual RNP model predicts an asymmetric protein distribution between the RNP that binds and methylates the substrate RNA. The predicted asymmetric nature of the holoenzyme is consistent with previous biochemical data on RNP assembly and provides a simple solution for accommodating base-pairing between the C/D guide RNA and large ribosomal and spliceosomal substrate RNAs. Copyright © 2010 Elsevier Inc. All rights reserved.

Lamellar ichthyosis (collodian baby with severe bilateral ectropion

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Boparai M

1988-01-01

Full Text Available A case of lamellar ichthyosis (collodian baby, is being reported. Skin biopsy has confirmed the diagnosis. Severe bilateral ectropion of thee eyelids was the prominent feature. Management of such cases has been briefly discussed.

Micro alloyed steel weldability and sensibility testing on the lamellar cracks appearance

Directory of Open Access Journals (Sweden)

S. Stojadinović

2011-07-01

Full Text Available In this work are given the testing results of mechanical properties welded joints and microstructure of micro alloyed steel as well as its sensitivity to lamellar cracks appearance. The obtained results show that steel has good resistance to lamellar cracks appearance and with an appropriate wire choice for welding, a good combination of mechanical properties could be obtained at room (ambience temperatures as well as at low temperatures.

A structural study of lamellar phases formed by nucleoside-functionalized lipids

CERN Document Server

Berti, D; Baglioni, P; Dante, S; Hauss, T

2002-01-01

We report a neutron-scattering investigation of lamellar phases formed by novel phospholipids bearing nucleosides at the polar-head-group region. These nucleolipids can interact through stacking and H-bond interactions, following a pattern that resembles base-base coupling in natural nucleic acids (DNA, RNA), i.e. they have similar recognition properties. Bilayer stacks formed of DPP-adenosine, DPP-uridine and their 1:1 mixture were investigated after equilibration in a 98% relative humidity atmosphere. The DPP-adenosine spectrum can be accounted for (in analogy to DPPC) by a lamellar phase with a smectic period of about 60 A. DPP-uridine displays a not so straightforward behavior that we have tentatively ascribed to the coexistence of lamellae with different smectic periods. In the 1:1 mixture the lamellar mesophase of DPP-uridine is retained, suggesting a specific interaction of the uridine polar-head group with the adenosine moiety of DPP-adenosine. It should be stressed that this behavior can be considere...

In-Situ TEM Study of Interface Sliding and Migration in an Ultrafine Lamellar Structure

Energy Technology Data Exchange (ETDEWEB)

Hsiung, L M

2005-12-06

The instability of interfaces in an ultrafine TiAl-({gamma})/Ti{sub 3}Al-({alpha}{sub 2}) lamellar structure by straining at room temperature has been investigated using in-situ straining techniques performed in a transmission electron microscope. The purpose of this study is to obtain experimental evidence to support the creep mechanisms based upon the interface sliding in association with a cooperative movement of interfacial dislocations previously proposed to interpret the nearly linear creep behavior observed from ultrafine lamellar TiAl alloys. The results have revealed that both the sliding and migration of lamellar interfaces can take place simultaneously as a result of the cooperative movement of interfacial dislocations.

How do closed-compact multi-lamellar droplets form under shear flow? A possible mechanism

Science.gov (United States)

Courbin, L.; Pons, R.; Rouch, J.; Panizza, P.

2003-01-01

The formation of closed-compact multi-lamellar droplets obtained upon shearing both a lamellar phase (Lα) and a two-phase separated lamellar-sponge (Lα-L3) mixture is investigated as a function of the shear rate dot gamma, using small-angle light scattering (SALS) and cross-polarized optical microscopy. In both systems the formation of droplets occurs homogeneously in the cell at a well-defined wave vector qe propto dot gamma1/3 via a strain-controlled process. These results suggest that the formation of droplets may be monitored in both systems by a buckling instability of the lamellae as predicted from a recent theory.

Association between lamellar body count and respiratory distress in neonates

International Nuclear Information System (INIS)

Bahasadri, Shoreh; Changizi, Nasrin

2005-01-01

Assessment of fetal lung maturity by a simple and rapid test has a pivotal role in obstetric managements. Lack of modern laboratory techniques in our country made US investigate whether lamellar body count (Lb) can be applied efficiently in the evaluation of fetal lung maturity. Lamellar body count was assessed in 104 un spun amniotic fluid samples taken from pregnant women admitted at A kbar Aba di Hospital, Tehran, Iran between May 2003 and November 2003 whose fetuses were at risk for respiratory distress syndrome (RDS). Cut-off points for LBC were determined to evaluate the risk of RDS. Standard clinical and radiographic criteria were used to diagnose RDS. An LBC of less than 10,000 was 99.1% specific for lung immaturity (positive predictive value = 99.1%, negative predictive value = 83.5%). The LBCs of greater than 45,000 eliminates RDS (negative predictive value = 98.9%). Lamellar body count is an easy, rapid and cost-effective test to assess fetal lung maturity in high-risk fetuses. Using the cut-off points of 10,000 and 45,000, LBC can serve as the first screening test of fetal lung maturity. (author)

Creep characteristics of a hypoeutectic Mg-Ca binary alloy with a near-fully lamellar microstructure

International Nuclear Information System (INIS)

Terada, Yoshihiro; Tsukahara, Masashi; Shibayama, Atsushi; Murata, Yoshinori; Morinaga, Masahiko

2011-01-01

Highlights: → We develop a hypoeutectic Mg-Ca cast alloy with a near-fully lamellar microstructure. → Dislocations are introduced within the lamellar microstructure during casting. → The dislocation segments in the α-Mg plates are located on the basal planes. → Creep of the alloy is ascribed to the easy glide of the introduced dislocations. -- The creep behavior of a hypoeutectic Mg-14.8 mass% Ca cast alloy with an α-Mg/C14-Mg 2 Ca near-fully lamellar microstructure was investigated at 473 K. Transmission electron microscopy shows that dislocations are introduced within the lamellar microstructure of the alloy during casting; the dislocation segments in the α-Mg plates are located on basal planes. The stress exponent of the creep rate is unity in the early stage of transient creep. Creep deformation of the alloy is ascribed to the easy glide of the introduced dislocations.

A Case Report of Ichthyosis Lamellar Syndrome

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Gh. Eshghi

2014-04-01

Full Text Available Introduction: Ichthyosis lamellar syndrome is a rare genodermatosis and in most families is inherited as an autosomal recessive trait because of transglutaminase-1 deficiency. Case Report: Our patient was a 6 year old girl and she was the result of consanguinity. She had large plate-like scales. The scales had mosaic-like pattern and erythroderma was absent. Tautness of her facial skin was associated with ectropion and eclabion and hypoplasia of auricular cartilages. She had scarring alopecia because of taut skin (specially at the periphery of scalp. She also had palmoplantar keratoderma and secondary nail dystrophy and thanked nails. Her parents also gave us the history of heat intolerance and it is because of interaepi-dermal constriction of sweat ducts. Our patient had the history of recurrent ear infections and it is because of accumulation of scales in the external ear. Conclusion: Our patient underwent a biopsy and based on our clinical findings her diagnosis was lamellar ichthyosis. (Sci J Hamadan Univ Med Sci 2014; 21 (1:76-79

Complications and Management of Deep Anterior Lamellar Keratoplasty

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Banu Torun Acar

2014-10-01

Full Text Available Objectives: To report the intraoperative and postoperative follow-up complications and management of these in deep anterior lamellar keratoplasty (DALK surgery. Materials and Methods: Two hundred eighty-four eyes of 252 patients followed up in our cornea clinic who underwent DALK using Anwar’s big-bubble technique with healthy Descemet’s membrane and endothelium were included in this study. Intraoperative and postoperative complications as well as the management and treatment of these complications were evaluated. Results: Big bubble was created in 220 (77.5% eyes of 284 eyes, and lamellar dissection was performed in 64 (22.5% eyes. Perforation occurred during trephination in 4 eyes, and the procedure was accomplished by penetrating keratoplasty (PK. Intraoperative microperforation occurred in 44 eyes. Perforation enlarged in 4 eyes and PK was performed. Operation was continued in 40 eyes with air injection into the anterior chamber. In postopertive follow-up period, double anterior chamber (DAC occurred in 32 of 40 eyes. DAC spontaneously regressed in 8 eyes, and air was given into the anterior chamber with a second surgical intervention in 24 eyes. DAC improved in 20 eyes. Four eyes underwent PK. Fungal keratitis evolved at the interface in one eye, because of no healing during the follow-up period, this eye underwent PK under antifungal therapy. Eyes with interface haze and Descemet’s membrane folds were followed. Conclusion: DALK is a difficult technique with a steep learning curve. In addition to the complications seen in PK, specific complications can occur in lamellar surgery. (Turk J Ophthalmol 2014; 44: 337-40

Hierarchical Ag mesostructures for single particle SERS substrate

Energy Technology Data Exchange (ETDEWEB)

Xu, Minwei, E-mail: xuminwei@xjtu.edu.cn; Zhang, Yin

2017-01-30

Highlights: • Hierarchical Ag mesostructures with the size of 250, 360 and 500 nm are synthesized via a seed-mediated approach. • The Ag mesostructures present the tailorable size and highly roughened surfaces. • The average enhancement factors for individual Ag mesostructures were estimated to be as high as 10{sup 6}. - Abstract: Hierarchical Ag mesostructures with highly rough surface morphology have been synthesized at room temperature through a simple seed-mediated approach. Electron microscopy characterizations indicate that the obtained Ag mesostructures exhibit a textured surface morphology with the flower-like architecture. Moreover, the particle size can be tailored easily in the range of 250–500 nm. For the growth process of the hierarchical Ag mesostructures, it is believed that the self-assembly mechanism is more reasonable rather than the epitaxial overgrowth of Ag seed. The oriented attachment of nanoparticles is revealed during the formation of Ag mesostructures. Single particle surface enhanced Raman spectra (sp-SERS) of crystal violet adsorbed on the hierarchical Ag mesostructures were measured. Results reveal that the hierarchical Ag mesostructures can be highly sensitive sp-SERS substrates with good reproducibility. The average enhancement factors for individual Ag mesostructures are estimated to be about 10{sup 6}.

A structural study of lamellar phases formed by nucleoside-functionalized lipids

Energy Technology Data Exchange (ETDEWEB)

Berti, D.; Fratini, E.; Baglioni, P. [Department of Chemistry and CSGI, University of Florence, Via G. Capponi 9, 50121 Florence (Italy); Dante, S.; Hauss, T. [Berlin Neutron Scattering Center, Hahn Meitner Institut, Glienicker Strasse 100, Wannsee, 14109 Berlin (Germany)

2002-07-01

We report a neutron-scattering investigation of lamellar phases formed by novel phospholipids bearing nucleosides at the polar-head-group region. These nucleolipids can interact through stacking and H-bond interactions, following a pattern that resembles base-base coupling in natural nucleic acids (DNA, RNA), i.e. they have similar recognition properties. Bilayer stacks formed of DPP-adenosine, DPP-uridine and their 1:1 mixture were investigated after equilibration in a 98% relative humidity atmosphere. The DPP-adenosine spectrum can be accounted for (in analogy to DPPC) by a lamellar phase with a smectic period of about 60 A. DPP-uridine displays a not so straightforward behavior that we have tentatively ascribed to the coexistence of lamellae with different smectic periods. In the 1:1 mixture the lamellar mesophase of DPP-uridine is retained, suggesting a specific interaction of the uridine polar-head group with the adenosine moiety of DPP-adenosine. It should be stressed that this behavior can be considered as an indication of the recognition process occurring at the polar-head-group region of the mixed phospholiponucleoside membrane. (orig.)

Structural studies of lamellar surfactant systems under shear

DEFF Research Database (Denmark)

Mortensen, K.

2001-01-01

Recent experimental studies on concentrated surfactant systems are reviewed. Particular attention is focused on the transformation from planar lamellar sheets to multilamellar vesicles. It is discussed whether both of these states are thermodynamic stable, or if the MLV is an artifact of shear in...

Incorporation of poly-saccharidic derivatives in model biological systems: monolayers, lamellar phases and vesicles

International Nuclear Information System (INIS)

Deme, Bruno

1995-01-01

Our aim is to introduce a soluble polymer in a lyotropic lamellar phase, and to modify the force balance in the case of a collapsed system where no repulsive contribution overcomes the van der Waals attraction, except at very short distances where hydration forces dominate (i.e. a collapsed stack of membranes). Mixed layers of a synthetic lecithin (DMPC) and a hydrophobically modified polysaccharide (cholesteryl-pullulan, CHP) have been investigated at the air-water interface by surface tension experiments and by specular reflection of neutrons. The DMPC/CHP/water ternary phase diagram has been determined by small angle X-ray scattering (SAXS) and small angle neutron scattering (SANS). CHP derivatives are associative polymers bearing lateral cholesterol groups that interact with a polar phases such as phospholipid monolayers and biological membranes. These derivatives are surface active and self-aggregate in solution leading to the formation of soluble micellar type aggregates. The interaction of CHP derivatives with lipidic structures involves the anchoring of the cholesterol groups that yields to the tethering of the poly-saccharidic backbones at lipid/water interfaces. These poly-saccharidic backbones are flexible chains in good solvent in water. Using these derivatives and a new preparation procedure, we show that it is possible to avoid the depletion of the polysaccharide due to its steric exclusion by the collapsed DMPC lamellar phase. We are able to prepare samples at thermodynamic equilibrium with the polysaccharide solubilized in the lamellar phase, a situation opposed to the well known behavior of mixed polysaccharide/lecithin Systems commonly used in osmotic stress experiments. Here, the osmotic pressure of the chains confined in the lamellar lattice acts as a new long range repulsive contribution in the DMPC lyotropic L_α phase and results in the swelling of the lamellar phase at large membrane separations (570 A). Such bilayer separations allow out of

Incidental Finding of Lamellar Calcification of the Falx Cerebri Leading to the Diagnosis of Gorlin-Goltz Syndrome

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I. Saulite

2013-10-01

Full Text Available Here, we report the case of an incidental finding of lamellar calcification of the falx cerebri in a routine computed tomography scan of the head after an accidental trauma. This lamellar calcification led to the diagnosis of Gorlin-Goltz syndrome (GGS in the patient and her daughter. Lamellar calcification of the falx cerebri is a pathognomonic feature of GGS. Our case report highlights the importance of a multidisciplinary diagnostic approach to GGS.

Incidental finding of lamellar calcification of the falx cerebri leading to the diagnosis of gorlin-goltz syndrome.

Science.gov (United States)

Saulite, I; Voykov, B; Mehra, T; Hoetzenecker, W; Guenova, E

2013-01-01

Here, we report the case of an incidental finding of lamellar calcification of the falx cerebri in a routine computed tomography scan of the head after an accidental trauma. This lamellar calcification led to the diagnosis of Gorlin-Goltz syndrome (GGS) in the patient and her daughter. Lamellar calcification of the falx cerebri is a pathognomonic feature of GGS. Our case report highlights the importance of a multidisciplinary diagnostic approach to GGS.

Finite element analysis for the initiation of lamellar tearing in welded joints

International Nuclear Information System (INIS)

Krieg, R.D.; Thomas, R.K.

1980-01-01

A numerical procedure using the finite element method is presented for predicting the initiation of lamellar tearing in fillet welded T-joints commonly employed in large structures. Starting with a prescribed geometry, the welding process is approximated by a known time-dependent volumetric heat source which simulates the arc heating and deposition of liquid metal. The transient nonlinear thermal and stress problems are then solved using finite element computer codes. Results of the elastic-plastic stress analysis are presented showing a predicted region of incipient lamellar tearing based on a ductile fracture theory which qualitatively agrees with the size and location of tears typically observed in photomicrographs. Additional insight into post failure crack length and stability is presented based on a simplified linear elastic fracture mechanics approach. Although the analysis procedure shows signs of promise, several weak points in the model are pointed out which must be improved before lamellar tearing can be quantified in an approach of this general type

Vacuolar ATPase regulates surfactant secretion in rat alveolar type II cells by modulating lamellar body calcium.

Directory of Open Access Journals (Sweden)

Narendranath Reddy Chintagari

2010-02-01

Full Text Available Lung surfactant reduces surface tension and maintains the stability of alveoli. How surfactant is released from alveolar epithelial type II cells is not fully understood. Vacuolar ATPase (V-ATPase is the enzyme responsible for pumping H(+ into lamellar bodies and is required for the processing of surfactant proteins and the packaging of surfactant lipids. However, its role in lung surfactant secretion is unknown. Proteomic analysis revealed that vacuolar ATPase (V-ATPase dominated the alveolar type II cell lipid raft proteome. Western blotting confirmed the association of V-ATPase a1 and B1/2 subunits with lipid rafts and their enrichment in lamellar bodies. The dissipation of lamellar body pH gradient by Bafilomycin A1 (Baf A1, an inhibitor of V-ATPase, increased surfactant secretion. Baf A1-stimulated secretion was blocked by the intracellular Ca(2+ chelator, BAPTA-AM, the protein kinase C (PKC inhibitor, staurosporine, and the Ca(2+/calmodulin-dependent protein kinase II (CaMKII, KN-62. Baf A1 induced Ca(2+ release from isolated lamellar bodies. Thapsigargin reduced the Baf A1-induced secretion, indicating cross-talk between lamellar body and endoplasmic reticulum Ca(2+ pools. Stimulation of type II cells with surfactant secretagogues dissipated the pH gradient across lamellar bodies and disassembled the V-ATPase complex, indicating the physiological relevance of the V-ATPase-mediated surfactant secretion. Finally, silencing of V-ATPase a1 and B2 subunits decreased stimulated surfactant secretion, indicating that these subunits were crucial for surfactant secretion. We conclude that V-ATPase regulates surfactant secretion via an increased Ca(2+ mobilization from lamellar bodies and endoplasmic reticulum, and the activation of PKC and CaMKII. Our finding revealed a previously unrealized role of V-ATPase in surfactant secretion.

Direct Visualisation of the Structural Transformation between the Lyotropic Liquid Crystalline Lamellar and Bicontinuous Cubic Mesophase.

Science.gov (United States)

Tran, Nhiem; Zhai, Jiali; Conn, Charlotte E; Mulet, Xavier; Waddington, Lynne J; Drummond, Calum J

2018-05-29

The transition between the lyotropic liquid crystalline lamellar and the bicontinuous cubic mesophase drives multiple fundamental cellular processes involving changes in cell membrane topology including endocytosis and membrane budding. While several theoretical models have been proposed to explain this dynamic transformation, experimental validation of these models has been challenging due to the short lived nature of the intermediates present during the phase transition. Herein, we report the direct observation of a lamellar to bicontinuous cubic phase transition in nanoscale dispersions using a combination of cryogenic transmission electron microscopy and static small angle X-ray scattering. The results represent the first experimental confirmation of a theoretical model which proposed that the bicontinuous cubic phase originates from the centre of a lamellar vesicle, then propagates outward via the formation of inter-lamellar attachments and stalks. The observation was possible due to the precise control of the lipid composition to place the dispersion systems at the phase boundary of a lamellar and a cubic phase, allowing for the creation of long-lived structural intermediates. By surveying the nanoparticles using cryogenic transmission electron microscopy, a complete phase transition sequence was established.

Lamellar γ-AlOOH architectures: Synthesis and application for the removal of HCN

International Nuclear Information System (INIS)

Hou Hongwei; Zhu You; Tang Gangling; Hu Qingyuan

2012-01-01

Using hexadecyl trimethyl ammonium bromide (CTAB) as a structure-directing agent and precipitator, the complete synthesis of lamellar γ-AlOOH architectures was successfully accomplished via a hydrothermal route. Different product structures were obtained by varying the molar ratio of aluminum nitrate and CTAB. Several techniques, including X-ray powder diffraction, Fourier transform infrared spectroscopy, field-emission scanning electron microscopy, transmission electron microscopy, and differential scanning calorimetry thermal analysis, were used to characterize the products. The effects of CTAB concentration, reaction temperature and time, and the molar ratio of Al 3+ /CTAB on the product morphologies were investigated. The nitrogen adsorption and desorption measurements indicated that the γ-AlOOH architectures possess a Brunauer–Emmett–Teller surface area of approximately 75.02 m 2 /g. It was also demonstrated that 10 mg γ-AlOOH architectures can remove 45.3% of the HCN (1.68 μg/mL) from model wastewater. When 0.03 mg/cig γ-AlOOH architectures were combined with cigarette paper, 8.12% of the present HCN was adsorbed. These results indicate that lamellar γ-AlOOH architectures may be a potential adsorbent for removing HCN from highly toxic pollutant solutions and harmful cigarette smoke. Highlights: ► Hexadecyl trimethyl ammonium bromide (CTAB) was used as a structure-directing agent and precipitator. ► Hydrothermal treatment enables growth of lamellar γ-AlOOH architectures. ► Lamellar γ-AlOOH architectures were demonstrated to exhibit high BET surface area and excellent adsorptive capacity. ► HCN in contaminated water and cigarette smoke can be effectively removed by the prepared lamellar γ-AlOOH superstructures.

One- and two-dimensional fluids properties of smectic, lamellar and columnar liquid crystals

CERN Document Server

Jakli, Antal

2006-01-01

Smectic and lamellar liquid crystals are three-dimensional layered structures in which each layer behaves as a two-dimensional fluid. Because of their reduced dimensionality they have unique physical properties and challenging theoretical descriptions, and are the subject of much current research. One- and Two-Dimensional Fluids: Properties of Smectic, Lamellar and Columnar Liquid Crystals offers a comprehensive review of these phases and their applications. The book details the basic structures and properties of one- and two-dimensional fluids and the nature of phase transitions. The later chapters consider the optical, magnetic, and electrical properties of special structures, including uniformly and non-uniformly aligned anisotropic films, lyotropic lamellar systems, helical and chiral structures, and organic anisotropic materials. Topics also include typical and defective features, magnetic susceptibility, and electrical conductivity. The book concludes with a review of current and potential applications ...

Fabrication of a superhydrophobic surface on a wood substrate

Science.gov (United States)

Wang, Shuliang; Shi, Junyou; Liu, Changyu; Xie, Cheng; Wang, Chengyu

2011-09-01

A layer of lamellar superhydrophobic coating was fabricated on a wood surface through a wet chemical process. The superhydrophobic property of the wood surface was measured by contact angle (CA) measurements. The microstructure and chemical composition of the superhydrophobic coating were analyzed by scanning electron microscopy (SEM), X-ray diffraction (XRD) and Fourier transform infrared spectroscopy (FT-IR). An analytical characterization revealed that the microscale roughness of the lamellar particles was uniformly distributed on the wood surface and that a zinc stearate monolayer (with the hydrophobic groups oriented outward) formed on the ZnO surface as the result of the reaction between stearic acid and ZnO. This process transformed the wood surface from hydrophilic to superhydrophobic: the water contact angle of the surface was 151°, and the sliding angle was less than 5°.

Alteration of biomass composition in response to changing substrate particle size and the consequences for enzymatic hydrolysis of corn bran

DEFF Research Database (Denmark)

Agger, Jane; Meyer, Anne S.

2012-01-01

Corn bran is a by-product from corn starch processing. This work examined the effects of changing substrate particle size on enzymatic hydrolysis of both raw and pretreated destarched corn bran. The biomass composition of the corn bran varied between particle size fractions: The largest particles...

In situ ultrahigh-resolution optical coherence tomography characterization of eye bank corneal tissue processed for lamellar keratoplasty.

Science.gov (United States)

Brown, Jamin S; Wang, Danling; Li, Xiaoli; Baluyot, Florence; Iliakis, Bernie; Lindquist, Thomas D; Shirakawa, Rika; Shen, Tueng T; Li, Xingde

2008-08-01

To use optical coherence tomography (OCT) as a noninvasive tool to perform in situ characterization of eye bank corneal tissue processed for lamellar keratoplasty. A custom-built ultrahigh-resolution OCT (UHR-OCT) was used to characterize donor corneal tissue that had been processed for lamellar keratoplasty. Twenty-seven donor corneas were analyzed. Four donor corneas were used as controls, whereas the rest were processed into donor corneal buttons for lamellar transplantation by using hand dissection, a microkeratome, or a femtosecond laser. UHR-OCT was also used to noninvasively characterize and monitor the viable corneal tissue immersed in storage medium over 3 weeks. The UHR-OCT captured high-resolution images of the donor corneal tissue in situ. This noninvasive technique showed the changes in donor corneal tissue morphology with time while in storage medium. The characteristics of the lamellar corneal tissue with each processing modality were clearly visible by UHR-OCT. The in situ characterization of the femtosecond laser-cut corneal tissue was noted to have more interface debris than shown by routine histology. The effects of the femtosecond laser microcavitation bubbles on the corneal tissue were well visualized at the edges of the lamellar flap while in storage medium. The results of our feasibility study show that UHR-OCT can provide superb, in situ microstructural characterization of eye bank corneal tissue noninvasively. The UHR-OCT interface findings and corneal endothelial disc thickness uniformity analysis are valuable information that may be used to optimize the modalities and parameters for lamellar tissue processing. The UHR-OCT is a powerful approach that will allow us to further evaluate the tissue response to different processing techniques for posterior lamellar keratoplasty. It may also provide information that can be used to correlate with postoperative clinical outcomes. UHR-OCT has the potential to become a routine part of tissue

Chain confinement, phase transitions, and lamellar structure in semicrystalline polymers, polymer blends and polymer nanocomposites

Science.gov (United States)

Chen, Huipeng

Recent studies suggest that there are three phase fractions in semicrystalline polymers, the crystalline, the mobile amorphous and the rigid amorphous phases. Due to the distinct properties of the rigid amorphous fraction, RAF, it has been investigated for more than twenty years. In this thesis, a general method using quasi-isothermal temperature-modulated differential scaning calorimetry, DSC, is provided for the first time to obtain the temperature dependent RAF and the other two fractions, crystalline fraction and mobile amorphous fraction, MAF. For poly(ethylene terephthalate), PET, our results show RAF was vitrified during quasi-isothermal cooling after crystallization had been completed and became totally devitrified during quasi-isothermal heating before the start of melting. Several years after people initially discovered the existence of RAF, another issue arose relating to the physical location of RAF and mobile amorphous fraction, MAF, within a lamellar stack model. Two very different models to describe the location of RAF were proposed. In the Heterogeneous Stack Model, HET, RAF is located outside the lamellar stacks. In the Homogeneous Stack Model, HSM, RAF was located inside the lamellar stacks. To determine the lamellar structure of semicrystalline polymers comprising three phase, a general method is given in this thesis by using a combination of the DSC and small angle X-ray scattering, SAXS techniques. It has been applied to Nylon 6, isotactic polystyrene, iPS, and PET. It was found for all of these materials, the HSM model is correct to describe the lamellar structure. In addition to the determination of lamellar structures, this method can also provide the exact fraction of MAF inside and outside lamellar stacks for binary polymer blends. For binary polymer blends, MAF, normally is located partially inside and partially outside the lamellar stacks. However, the quantification of the MAF inside and outside the lamellar stacks has now been provided

Imaging of the vertical particle tracks without any depth scanning

International Nuclear Information System (INIS)

Soroko, L.M.

2001-01-01

The principle of a new optical microscope which enables us to get the image of a vertical particle track without any depth scanning is described. This new optical microscope contains a spatial transformer which consists of mirror lamellar elements and which produces a secondary in focus image of the vertical particle track. Properties of such a system are presented. A longitudinal resolution is estimated

The estimate of permittivity of anisotropic composites with lamellar inclusions by the self-assessment method

Directory of Open Access Journals (Sweden)

V. S. Zarubin

2015-01-01

Full Text Available Composites are widely used as structural or thermal protection materials; they are used as well as functional materials in a large number of different electrical devices and as dielectrics. This composite has one of the most important characteristics the relative permittivity. It depends primarily on the dielectric properties of the inclusions and the matrix as well as the shape and volume content of the inclusions.In this paper, a mathematical model of the interaction of the electrostatic fields in an isotropic plate and in the surrounding homogeneous anisotropic medium is constructed. This model describes the dielectric properties of the composite with such inclusions. A variant of the same orientation of lamellar inclusions is considered, which leads to the special case of anisotropy of the dielectric properties of the composite that has transverse isotropy towards the direction perpendicular to the inclusions. The shape of inclusions is represented as an oblate ellipsoid of revolution (spheroid. Transformation of the differential equation describing the distribution of the electric potential transversely to isotropic medium surrounding the spheroidal inclusion, to the Laplace equation with the subsequent transition from the initial spheroid to the given ellipsoid of rotation allows us to apply the self-assessment method for the determination of the dielectric properties of the composite. This method equates the result of averaging the perturbation of the electrostatic field in the inclusions and the matrix particles towards the unperturbed fields in the environment to zero.The constructed mathematical model allows us to determine the electrostatic field disturbance in the inclusions and the matrix particles towards the unperturbed field given in the environment at a distance from the inclusions and the matrix particles, much larger than their characteristic dimensions. By averaging the perturbation of the electrostatic field in all the

Lamellar Diblock Copolymer Thin Films during Solvent Vapor Annealing Studied by GISAXS

DEFF Research Database (Denmark)

Zhang, Jianqi; Posselt, Dorthe; Smilgies, Detlef-M.

2014-01-01

The reorientation of lamellae and the dependence of the lamellar spacing, Dlam, on polymer volume fraction, ϕP, Dlam ∝ ϕP–β, in diblock copolymer thin films during solvent vapor annealing (SVA) are examined by combining white light interferometry (WLI) and grazing-incidence small-angle X-ray scat......The reorientation of lamellae and the dependence of the lamellar spacing, Dlam, on polymer volume fraction, ϕP, Dlam ∝ ϕP–β, in diblock copolymer thin films during solvent vapor annealing (SVA) are examined by combining white light interferometry (WLI) and grazing-incidence small-angle X...

Fabrication of substrates with curvature for cell cultivation by alpha-particle irradiation and chemical etching of PADC films

International Nuclear Information System (INIS)

Ng, C.K.M.; Tjhin, V.T.; Lin, A.C.C.; Cheng, J.P.; Cheng, S.H.; Yu, K.N.

2012-01-01

In the present paper, we developed a microfabrication technology to generate cell-culture substrates with identical chemistry and well-defined curvature. Micrometer-sized pits with curved surfaces were created on a two-dimensional surface of a polymer known as polyallyldiglycol carbonate (PADC). A PADC film was first irradiated by alpha particles and then chemically etched under specific conditions to generate pits with well-defined curvature at the incident positions of the alpha particles. The surface with these pits was employed as a model system for studying the effects of substrate curvature on cell behavior. As an application, the present work studied mechanosensing of substrate curvature by epithelial cells (HeLa cells) through regulation of microtubule (MT) dynamics. We used end-binding protein 3–green fluorescent protein (EB3–GFP) as a marker of MT growth to show that epithelial cells having migrated into the pits with curved surfaces had significantly smaller MT growth speeds than those having stayed on flat surfaces without the pits.

Hybrid Technique of Lamellar Keratoplasty (DMEK-S

Directory of Open Access Journals (Sweden)

Pavel Studeny

2013-01-01

Full Text Available Purpose: To evaluate the outcomes of the hybrid technique of posterior lamellar keratoplasty (DMEK-S. Materials and Methods: 71 eyes of 55 patients enrolled in a single-center study underwent posterior lamellar keratoplasty with a hybrid lamella DMEK-S implanted using a solution implantation technique, owing to endothelial dysfunction. The outcome measures studied were visual acuity and endothelial cell density. Results: The rate of endothelial cell loss caused by surgery was 43.8%. During followups, we observed the stabilization of postoperative findings, or at minimum a very low rate of corneal endothelial cell loss. The UCDVA and BCDVA dramatically improved postoperatively. The rebubbling rate in our group of patients was 61.9%. We replaced the lamella due to its failure or malfunction in 17 patients (23.9%. Conclusion: In summary, DMEK-S combines the advantages of DSEK/DSAEK and DMEK. The central zone of bare Descemet’s membrane and endothelium allows for very good visual outcomes, and the peripheral rim allows for better manipulation of the lamella during implantation. It is an effective method of treating the endothelial dysfunction of various etiologies, but the high complication rate needs to be addressed before widespread implementation of the technique in the future.

Virus-sized self-assembling lamellar complexes between plasmid DNA and cationic micelles promote gene transfer

Science.gov (United States)

Pitard, Bruno; Aguerre, Olivier; Airiau, Marc; Lachagès, Anne-Marie; Boukhnikachvili, Tsiala; Byk, Gérardo; Dubertret, Catherine; Herviou, Christian; Scherman, Daniel; Mayaux, Jean-François; Crouzet, Joël

1997-01-01

Gene therapy is based on the vectorization of genes to target cells and their subsequent expression. Cationic amphiphile-mediated delivery of plasmid DNA is the nonviral gene transfer method most often used. We examined the supramolecular structure of lipopolyamine/plasmid DNA complexes under various condensing conditions. Plasmid DNA complexation with lipopolyamine micelles whose mean diameter was 5 nm revealed three domains, depending on the lipopolyamine/plasmid DNA ratio. These domains respectively corresponded to negatively, neutrally, and positively charged complexes. Transmission electron microscopy and x-ray scattering experiments on complexes originating from these three domains showed that although their morphology depends on the lipopolyamine/plasmid DNA ratio, their particle structure consists of ordered domains characterized by even spacing of 80 Å, irrespective of the lipid/DNA ratio. The most active lipopolyamine/DNA complexes for gene transfer were positively charged. They were characterized by fully condensed DNA inside spherical particles (diameter: 50 nm) sandwiched between lipid bilayers. These results show that supercoiled plasmid DNA is able to transform lipopolyamine micelles into a supramolecular organization characterized by ordered lamellar domains. PMID:9405626

Minimal compliance design for metal–ceramic composites with lamellar microstructures

DEFF Research Database (Denmark)

Piat, R.; Sinchuk, Y.; Vasoya, M.

2011-01-01

of lamellar domains. With local ceramic volume fraction and lamella orientation chosen as the design variables, a minimum compliance optimization problem is solved based on topology optimization and finite element methods for metal–ceramic samples with different geometries and boundary conditions...

One-step exfoliation and surface modification of lamellar hydroxyapatite by intercalation of glucosamine

Energy Technology Data Exchange (ETDEWEB)

Luo, Honglin [Research Institute for Biomaterials and Transportation, East China Jiaotong University, Nanchang, 330013 (China); School of Materials Science and Engineering, Tianjin University, Tianjin, 300072 (China); Li, Wei; Ji, Dehui [Research Institute for Biomaterials and Transportation, East China Jiaotong University, Nanchang, 330013 (China); Zuo, Guifu [Hebei Provincial Key Laboratory of Inorganic Nonmetallic Materials, College of Materials Science and Engineering, Hebei United University, Tangshan, 063009 (China); Xiong, Guangyao, E-mail: xiongguangyao@163.com [Research Institute for Biomaterials and Transportation, East China Jiaotong University, Nanchang, 330013 (China); Zhu, Yong [School of Chemical Engineering, Tianjin University, Tianjin, 300072 (China); Li, Lili; Han, Ming [Research Institute for Biomaterials and Transportation, East China Jiaotong University, Nanchang, 330013 (China); Wu, Caoqun [School of Materials Science and Engineering, Tianjin University, Tianjin, 300072 (China); Wan, Yizao, E-mail: yzwantju@126.com [Research Institute for Biomaterials and Transportation, East China Jiaotong University, Nanchang, 330013 (China); School of Materials Science and Engineering, Tianjin University, Tianjin, 300072 (China)

2016-04-15

Effective exfoliation is crucial to the application of layered materials in many fields. Herein, we report a novel effective, scalable, and ecofriendly method for the exfoliation of lamellar HAp by glucosamine intercalation such that individual HAp nanoplates can be obtained. The as-exfoliated HAp nanoplates were characterized by Fourier transform infrared (FTIR), X-ray diffraction (XRD), transmission electron microscopy (TEM), and thermogravimetric (TG) analysis. It is found that the glucosamine intercalation not only results in complete exfoliation of lamellar HAp but also introduces the glucosamine molecules onto the surface of individual HAp nanoplates, thus obtaining separated glucosamine-grafted HAp nanoplates (Glu-HAps). Results from MTT assay demonstrate that glucosamine grafting on HAp nanoplates greatly improves the cell growth and proliferation as compared to nongrafted HAp counterparts. - Highlights: • Glucosamine was used as intercalation agent to exfoliate lamellar hydroxyapatite. • Glucosamine was grafted onto the as-exfoliated nanoplate-like hydroxyapatite. • Exfoliation and surface grafting were accomplished in one step. • Glucosamine-grafted HAp showed improved biocompatibility over nongrafted one.

Two types of lamellar phase in TTAB/water/pentanol system as detected by positron lifetime spectroscopy

International Nuclear Information System (INIS)

Khani, P.H.; Yadav, R.; Singh, K.C.; Jain, P.C.

2004-01-01

Positron lifetime measurements were performed in TTAB(Tetradecyl trimethyl ammonium bromide)/water/pentanol ternary systems prepared by adding varying amounts of pentanol to different mother solutions of TTAB/water system having fixed TTAB concentrations. Besides delineating various phase boundaries as obtained by other conventional techniques, positron annihilation parameters were also found to be sensitive in detecting two kinds of lamellar structures in the otherwise considered to be a single liquid crystalline D phase of the system. The existence of such lamellar structures has been demonstrated by a change in the trend of o-Ps lifetime parameter when the system passes from one type of lamellar structure to the other type. The results of such a finding are presented in this paper. (orig.)

Inverse cutting of posterior lamellar corneal grafts by a femtosecond laser.

Science.gov (United States)

Hjortdal, Jesper; Nielsen, Esben; Vestergaard, Anders; Søndergaard, Anders

2012-01-01

Posterior lamellar grafting of the cornea has become the preferred technique for treatment of corneal endothelial dysfunction. Posterior lamellar grafts are usually cut by a micro-keratome or a femto-second laser after the epithelial side of the donor cornea has been applanated. This approach often results in variable central graft thickness in different grafts and an increase in graft thickness towards the periphery in every graft. The purpose of this study was to evaluate if posterior lamellar grafts can be prepared from the endothelial side by a femto-second laser, resulting in reproducible, thin grafts of even thickness. A CZM 500 kHz Visumax femto-second laser was used. Organ cultured donor grafts were mounted in an artifical anterior chamber with the endothelial side up and out. Posterior grafts of 7.8 mm diameter and 130 micron thickness were prepared by femto-second laser cutting. A standard DSAEK procedure was performed in 10 patients with Fuchs endothelial dystrophy. Patients were followed-up regularly and evaluated by measurement of complications, visual acuity, corneal thickness (Pentacam HR), and endothelial cell density. Femto-laser cutting of grafts and surgery was uncomplicated. Rebubbling was necessary in 5 of 10 cases (normally only in 1 of 20 cases). All grafts were attached and cleared up during the first few weeks. After six months, the average visual acuity was 0.30 (range: 0.16 to 0.50), corneal thickness was 0.58 mm (range 0.51 to 0.63), and endothelial cell density was 1.570 per sq. mm (range: 1.400 to 2.000 cells per sq. mm). The grafts were of uniform thickness, but substantial interface haze was present in most grafts. Posterior lamellar corneal grafts can be prepared from the endothelial side using a femto-second laser. All grafts were clear after 6 months with satisfying endothelial cell counts. Poor visual acuity caused by interface scatter was observed in most patients. Femto-second laser cutting parameters needs to be optimised to

Outstanding compressive creep strength in Cr/Ir-codoped (Mo0.85Nb0.15)Si2 crystals with the unique cross-lamellar microstructure.

Science.gov (United States)

Hagihara, Koji; Ikenishi, Takaaki; Araki, Haruka; Nakano, Takayoshi

2017-06-21

A (Mo 0.85 Nb 0.15 )Si 2 crystal with an oriented, lamellar, C40/C11 b two-phase microstructure is a promising ultrahigh-temperature (UHT) structural material, but its low room-temperature fracture toughness and low high-temperature strength prevent its practical application. As a possibility to overcome these problems, we first found a development of unique "cross-lamellar microstructure", by the cooping of Cr and Ir. The cross-lamellar microstructure consists of a rod-like C11 b -phase grains that extend along a direction perpendicular to the lamellar interface in addition to the C40/C11 b fine lamellae. In this study, the effectiveness of the cross-lamellar microstructure for improving the high-temperature creep deformation property, being the most essential for UHT materials, was examined by using the oriented crystals. The creep rate significantly reduced along a loading orientation parallel to the lamellar interface. Furthermore, the degradation in creep strength for other loading orientation that is not parallel to the lamellar interface, which has been a serious problem up to now, was also suppressed. The results demonstrated that the simultaneous improvement of high-temperature creep strength and room temperature fracture toughness can be first accomplished by the development of unique cross-lamellar microstructure, which opens a potential avenue for the development of novel UHT materials as alternatives to existing Ni-based superalloys.

Lamellar-crossing-structured Ni(OH){sub 2}/CNTs/Ni(OH){sub 2} nanocomposite for electrochemical supercapacitor materials

Energy Technology Data Exchange (ETDEWEB)

Wu, Qingnan [Department of Chemistry, State Key Laboratory of Pollution Control and Resource Reuse, Tongji University, Shanghai 200092 (China); Wen, Ming, E-mail: m_wen@tongji.edu.cn [Department of Chemistry, State Key Laboratory of Pollution Control and Resource Reuse, Tongji University, Shanghai 200092 (China); Shanghai Key Lab of Chemical Assessment and Sustainability, Tongji University, Shanghai 200092 (China); Chen, Shipei [Department of Chemistry, State Key Laboratory of Pollution Control and Resource Reuse, Tongji University, Shanghai 200092 (China); Wu, Qingsheng [Department of Chemistry, State Key Laboratory of Pollution Control and Resource Reuse, Tongji University, Shanghai 200092 (China); Shanghai Key Lab of Chemical Assessment and Sustainability, Tongji University, Shanghai 200092 (China)

2015-10-15

Ni(OH){sub 2}/CNTs/Ni(OH){sub 2} lamellar-crossing-nanostructure with a single lamellar spacing of ∼5 nm was effectively constructed through two-phase-interface reaction process followed by the CNTs crossed among the lamellar-nanostructured Ni(OH){sub 2}. The resultant nanocomposite can offer large active surface areas and short diffusion paths for electrons and ions, and is investigated as a potential pseudocapacitor electrode material for electrochemical energy storage applications. Electrochemical data demonstrate that the as-prepared nanocomposite exhibits a high specific capacitance of ∼1600 F g{sup −1} at the scan rate of 1 mV s{sup −1} in 6 M KOH solution at normal pressure and temperature, which is great higher than Ni(OH){sub 2} (∼1200 F g{sup −1}). Furthermore, Ni(OH){sub 2}/CNTs/Ni(OH){sub 2} nanocomposite shows a higher energy density (∼125 Wh kg{sup −1}, 2 A g{sup −1}) and has a slightly decrease of 5% in specific capacitance after 1000 continuous charge/discharge cycles. - Graphical abstract: As-constructed Ni(OH){sub 2}/CNTs/Ni(OH){sub 2} lamellar-crossing-nanostructure exhibits remarkable enhancement in electrochemical stability and high specific capacity of ∼1600 F g{sup −1} at a scan rate of 1 mV s{sup −1}, suggesting promising potential for supercapacitor applications. - Highlights: • New designed lamellar-crossing-structured Ni(OH){sub 2}/CNTs/Ni(OH){sub 2} nanocomposites have been firstly reported in this work. • Ni(OH){sub 2}/CNTs/Ni(OH){sub 2} lamellar-crossing-nanostructures show firm nanostructure and excellent electrochemical stability. • Ni(OH){sub 2}/CNTs/Ni(OH){sub 2} nanocomposites exhibit excellent specific capacitance. • Ni(OH){sub 2}/CNTs/Ni(OH){sub 2} nanocomposites have the potential application in electrochemical energy storage applications.

Electrochemical properties and diffusion of a redox active surfactant incorporated in bicontinuous cubic and lamellar phase

International Nuclear Information System (INIS)

Kostela, J.; Elmgren, M.; Almgren, M.

2005-01-01

The objective of this study was to investigate the electrochemical behaviour of the divalent redox active surfactant, N-cetyl-N'-methylviologen (CMV), in bicontinuous cubic and lamellar phases. The liquid crystalline phases were prepared from the system glycerolmonooleate (GMO)-water (and brine)-cationic surfactant. A comparison of the phase behaviour of GMO with the monovalent cetyltrimethylammonium bromide (CTAB) and the divalent CMV surfactant showed that the surfactants gave about the same effect at the same surface charge density. The electrochemical measurements were made with a mixture of CTAB and CMV as the surfactant. Cyclic voltammetry was used to study the electrochemistry of CMV incorporated in the cubic and lamellar phases that were spread on a gold electrode. The E 0 -values in the cubic samples were more negative (-0.55 V versus SCE) than in the lamellar samples (-0.53 V versus SCE). This can be explained by the higher charge density in the lamellar phase. The diffusion coefficients were also measured in the cubic phase. The mass transport is slowed down about fifty times in the cubic phase compared to in the pure electrolyte. The concentration dependence on the diffusion coefficient was also investigated. No electron hopping could be observed, which suggest that diffusional movement of the redox probe is the main source of charge transport. By placing the samples on a conducting glass slide, spectroelectrochemical investigations were performed. In the lamellar phase strong dimerization was detected at high concentration of viologen, but much less in the cubic phase

Electrochemical properties and diffusion of a redox active surfactant incorporated in bicontinuous cubic and lamellar phase

Energy Technology Data Exchange (ETDEWEB)

Kostela, J. [Uppsala University, Department of Physical Chemistry, Box 579, S-75123 Uppsala (Sweden)]. E-mail: johan.kostela@fki.uu.se; Elmgren, M. [Uppsala University, Department of Physical Chemistry, Box 579, S-75123 Uppsala (Sweden); Almgren, M. [Uppsala University, Department of Physical Chemistry, Box 579, S-75123 Uppsala (Sweden)

2005-05-30

The objective of this study was to investigate the electrochemical behaviour of the divalent redox active surfactant, N-cetyl-N'-methylviologen (CMV), in bicontinuous cubic and lamellar phases. The liquid crystalline phases were prepared from the system glycerolmonooleate (GMO)-water (and brine)-cationic surfactant. A comparison of the phase behaviour of GMO with the monovalent cetyltrimethylammonium bromide (CTAB) and the divalent CMV surfactant showed that the surfactants gave about the same effect at the same surface charge density. The electrochemical measurements were made with a mixture of CTAB and CMV as the surfactant. Cyclic voltammetry was used to study the electrochemistry of CMV incorporated in the cubic and lamellar phases that were spread on a gold electrode. The E {sup 0}-values in the cubic samples were more negative (-0.55 V versus SCE) than in the lamellar samples (-0.53 V versus SCE). This can be explained by the higher charge density in the lamellar phase. The diffusion coefficients were also measured in the cubic phase. The mass transport is slowed down about fifty times in the cubic phase compared to in the pure electrolyte. The concentration dependence on the diffusion coefficient was also investigated. No electron hopping could be observed, which suggest that diffusional movement of the redox probe is the main source of charge transport. By placing the samples on a conducting glass slide, spectroelectrochemical investigations were performed. In the lamellar phase strong dimerization was detected at high concentration of viologen, but much less in the cubic phase.

The ultra-structural organization of the elastic network in the intra- and inter-lamellar matrix of the intervertebral disc.

Science.gov (United States)

Tavakoli, J; Elliott, D M; Costi, J J

2017-08-01

The inter-lamellar matrix (ILM)-located between adjacent lamellae of the annulus fibrosus-consists of a complex structure of elastic fibers, while elastic fibers of the intra-lamellar region are aligned predominantly parallel to the collagen fibers. The organization of elastic fibers under low magnification, in both inter- and intra-lamellar regions, was studied by light microscopic analysis of histologically prepared samples; however, little is known about their ultrastructure. An ultrastructural visualization of elastic fibers in the inter-lamellar matrix is crucial for describing their contribution to structural integrity, as well as mechanical properties of the annulus fibrosus. The aims of this study were twofold: first, to present an ultrastructural analysis of the elastic fiber network in the ILM and intra-lamellar region, including cross section (CS) and in-plane (IP) lamellae, of the AF using Scanning Electron Microscopy (SEM) and second, to -compare the elastic fiber orientation between the ILM and intra-lamellar region. Four samples (lumbar sheep discs) from adjacent sections (30μm thickness) of anterior annulus were partially digested by a developed NaOH-sonication method for visualization of elastic fibers by SEM. Elastic fiber orientation and distribution were quantified relative to the tangential to circumferential reference axis. Visualization of the ILM under high magnification revealed a dense network of elastic fibers that has not been previously described. Within the ILM, elastic fibers form a complex network, consisting of different size and shape fibers, which differed to those located in the intra-lamellar region. For both regions, the majority of fibers were oriented near 0° with respect to tangential to circumferential (TCD) direction and two minor symmetrical orientations of approximately±45°. Statistically, the orientation of elastic fibers between the ILM and intra-lamellar region was not different (p=0.171). The present study used

Oligosaccharides and glycolipids addition in charged lamellar phases; Addition d`oligosaccharides et de glycolipides dans des phases lamellaires chargees

Energy Technology Data Exchange (ETDEWEB)

Ricoul, F

1997-09-26

The aim of this work is to study the addition of oligosaccharides and glycolipids in lamellar phases of the cationic surfactant DDAB (di-dodecyl-dimethyl-ammonium bromide). Two steps have been followed: the determination of phases prisms and the thermodynamic interpretation in terms of molecular interactions. In order to characterize these systems, two new experimental small angle scattering methods have been perfected: 1) a neutron scattering contrast variation method which allows to study the adsorption of aqueous solution in bilayers and 2) a capillary concentration gradient method to establish directly and quantitatively the phases diagrams of ternary systems by X rays scattering. It has been pointed out that the oligosaccharides induce a depletion attractive force on the lamellar-lamellar equilibrium of the DDAB when they are excluded of the most concentrated phase. For the two studied glycolipids: 2-O lauroyl-saccharose and N-lauroyl N-nonyl lactitol, the ternary phase diagrams water-DDAB-glycolipid have been established in terms of temperature. Critical points at ambient temperature have been given. The osmotic pressure in concentrated lamellar phases has been measured. It has been shown that glycolipids increase the hydration repulsion at short distance and that the electrostatic repulsion is outstanding and unchanged at high distance if there is at less 1 mole percent of ionic surfactant. In a dilute solution, glycolipids decrease the maximum swelling of lamellar phases, with a competition between the lamellar phase and the micellae dilute phase for water. (O.M.). 165 refs.

Hierarchical silica particles by dynamic multicomponent assembly

DEFF Research Database (Denmark)

Wu, Z. W.; Hu, Q. Y.; Pang, J. B.

2005-01-01

Abstract: Aerosol-assisted assembly of mesoporous silica particles with hierarchically controllable pore structure has been prepared using cetyltrimethylammonium bromide (CTAB) and poly(propylene oxide) (PPO, H[OCH(CH3)CH2],OH) as co-templates. Addition of the hydrophobic PPO significantly...... influences the delicate hydrophilic-hydrophobic balance in the well-studied CTAB-silicate co-assembling system, resulting in various mesostructures (such as hexagonal, lamellar, and hierarchical structure). The co-assembly of CTAB, silicate clusters, and a low-molecular-weight PPO (average M-n 425) results...... in a uniform lamellar structure, while the use of a high-molecular-weight PPO (average M-n 2000), which is more hydrophobic, leads to the formation of hierarchical pore structure that contains meso-meso or meso-macro pore structure. The role of PPO additives on the mesostructure evolution in the CTAB...

Morphological abnormalities and apoptosis in lamellar tissue of equines after intestinal obstruction and treatment with hydrocortisone

Directory of Open Access Journals (Sweden)

L.M Laskoski

2010-12-01

Full Text Available Four experimental groups of equines were used in order to study morphological abnormalities and apoptosis in lamellar tissue. Group Cg (control was composed of animals without any surgical procedure; group Ig (instrumented, animals that underwent enterotomy; group Tg (treated, animals that were subjected to intestinal obstruction and were treated with hydrocortisone; and group Ug (untreated, animals that were subjected to intestinal obstruction without treatment. The lamellar tissue was analyzed regarding the presence of tissue abnormalities and apoptosis. No morphological abnormalities were observed in animals of surgical groups, and no difference in apoptosis was observed between groups. It was concluded that intestinal obstruction allowed laminitis to develop, probably by systemic activation, and that the maneuvers performed in the enterotomy aggravated the process. Hydrocortisone did not aggravate the lesions of the lamellar tissue

Study of substrate topographical effects on epithelial cell behavior using etched alpha-particle tracks on PADC films

International Nuclear Information System (INIS)

Ng, C.K.M.; Poon, W.L.; Li, W.Y.; Cheung, T.; Cheng, S.H.; Yu, K.N.

2008-01-01

Micrometer-size pits on the surface of a polymer (polyallyldiglycol carbonate or PADC) substrate created by alpha-particle irradiation and subsequent chemical etching were used to study the topographical effects alone on cell behavior. Vinculin, the cell adhesion and membrane protrusion protein, was used as an indicator of cytoskeletonal reorganization on the substrate and localization of vinculin was used to demonstrate the presence of focal adhesions. In our experiments, vinculin expressed in epithelial HeLa cells cultured on PADC films with track-etch pits, but not in cells cultured on the raw or chemically etched blank films. In other words, vinculin expression was induced by the topography of track-etch pits, while etching of the substrate alone (without alpha-particle irradiation) did not cause up-regulation of vinculin protein expression. HeLa cells cultured on PADC films with track-etch pits also showed changes in cell proliferation, cell area and cell circularity, and were largely contained by the pits. In other words, the cell membrane edges tended to be in contact with the pits. By comparing the correlation between the positions of HeLa cells and the pits, and that between the positions of cells and computer-simulated pits, the tendency for membrane edges of HeLa cells to be in contact with the pits was recognized. This could be explained by inhibition of membrane protrusion at the pits. In conclusion, substrate track-etch pits were an important determinant of epithelial cell behaviors

Reverse osmosis desalination of chitosan cross-linked graphene oxide/titania hybrid lamellar membranes.

Science.gov (United States)

Deng, Hui; Sun, Penzhan; Zhang, Yingjiu; Zhu, Hongwei

2016-07-08

With excellent mass transport properties, graphene oxide (GO)-based lamellar membranes are believed to have great potential in water desalination. In order to quantify whether GO-based membranes are indeed suitable for reverse osmosis (RO) desalination, three sub-micrometer thick GO-based lamellar membranes: GO-only, reduced GO (RGO)/titania (TO) nanosheets and RGO/TO/chitosan (CTS) are prepared, and their RO desalination performances are evaluated in a home-made RO test apparatus. The photoreduction of GO by TO improves the salt rejection, which increases slowly with the membrane thickness. The RGO/TO/CTS hybrid membranes exhibit higher rejection rates of only about 30% (greater than threefold improvement compared with a GO-only membrane) which is still inferior compared to other commercial RO membranes. The low rejection rates mainly arise from the pressure-induced weakening of the ion-GO interlayer interactions. Despite the advantages of simple, low-cost preparation, high permeability and selectivity of GO-based lamellar membranes, as the current desalination performances are not high enough to afford practical application, there still remains a great challenge to realize high performance separation membranes for water desalination applications.

Optically controlled electrophoresis with a photoconductive substrate

Science.gov (United States)

Inami, Wataru; Nagashima, Taiki; Kawata, Yoshimasa

2018-05-01

A photoconductive substrate is used to perform electrophoresis. Light-induced micro-particle flow manipulation is demonstrated without using a fabricated flow channel. The path along which the particles were moved was formed by an illuminated light pattern on the substrate. Because the substrate conductivity and electric field distribution can be modified by light illumination, the forces acting on the particles can be controlled. This technique has potential applications as a high functionality analytical device.

Wear Evaluation of AISI 4140 Alloy Steel with WC/C Lamellar Coatings Sliding Against EN 8 Using Taguchi Method

Science.gov (United States)

Kadam, Nikhil Rajendra; Karthikeyan, Ganesarethinam

2016-10-01

The purpose of the experiments in this paper is to use the Taguchi methods to investigate the wear of WC/C coated nitrided AISI 4140 alloy steel. A study of lamellar WC/C coating which were deposited by a physical vapor deposition on nitrided AISI 4140 alloy steel. The investigation includes wear evaluation using Pin-on-disk configuration. When WC/C coated AISI 4140 alloy steel slides against EN 8 steel, it was found that carbon-rich coatings show much lower wear of the countersurface than nitrogen-rich coatings. The results were correlated with the properties determined from tribological and mechanical characterization, therefore by probably selecting the proper processing parameters the deposition of WC/C coating results in decreasing the wear rate of the substrate which shows a potential for tribological application.

Large area, soft crystalline thin films of N,N' ,N'' -trialkyltriazatriangulenium salts with homeotropic alignment of the discotic cores in a lamellar lattice

DEFF Research Database (Denmark)

Just Sørensen, Thomas; Hildebrandt, Christoffer B.; Elm, Jonas

2012-01-01

techniques confirm that the 15–30 nm thick films maintain the lamellar structure of the bulk crystals, are flat on macroscopic length scales, and are completely ordered relative to the substrate. The triazatriangulenium molecules are electroactive dyes, and in the highly anisotropic polycrystalline thin film......N,N' ,N'' -Trialkyltriazatriangulenium (R-TATA+) tetrafluoroborate (BF4) salts form highly ordered thin films directly when spin-cast onto rotating substrates. The homogeneous and crystalline thin films show macroscopic order over centimetres. The crystal structures of the R-TATA$BF4 salts...... are investigated and compared for the propyl, 3-methylpentyl and octyl derivatives. In all cases the molecules pack in hexagonally ordered bilayers, with segregation of the ionic groups and the alkyl chains. This is a rare packing motif with the rigid discotic TATA+ cores organized co-planarly in sheets separated...

Structure-rheology relationship in a sheared lamellar fluid.

Science.gov (United States)

Jaju, S J; Kumaran, V

2016-03-01

The structure-rheology relationship in the shear alignment of a lamellar fluid is studied using a mesoscale model which provides access to the lamellar configurations and the rheology. Based on the equations and free energy functional, the complete set of dimensionless groups that characterize the system are the Reynolds number (ργL(2)/μ), the Schmidt number (μ/ρD), the Ericksen number (μγ/B), the interface sharpness parameter r, the ratio of the viscosities of the hydrophilic and hydrophobic parts μ(r), and the ratio of the system size and layer spacing (L/λ). Here, ρ and μ are the fluid density and average viscosity, γ is the applied strain rate, D is the coefficient of diffusion, B is the compression modulus, μ(r) is the maximum difference in the viscosity of the hydrophilic and hydrophobic parts divided by the average viscosity, and L is the system size in the cross-stream direction. The lattice Boltzmann method is used to solve the concentration and momentum equations for a two dimensional system of moderate size (L/λ=32) and for a low Reynolds number, and the other parameters are systematically varied to examine the qualitative features of the structure and viscosity evolution in different regimes. At low Schmidt numbers where mass diffusion is faster than momentum diffusion, there is fast local formation of randomly aligned domains with "grain boundaries," which are rotated by the shear flow to align along the extensional axis as time increases. This configuration offers a high resistance to flow, and the layers do not align in the flow direction even after 1000 strain units, resulting in a viscosity higher than that for an aligned lamellar phase. At high Schmidt numbers where momentum diffusion is fast, the shear flow disrupts layers before they are fully formed by diffusion, and alignment takes place by the breakage and reformation of layers by shear, resulting in defects (edge dislocations) embedded in a background of nearly aligned layers

Creep mechanisms of fully-lamellar TiAl based upon interface sliding

International Nuclear Information System (INIS)

Hsiung, L.M.; Nieh, T.G.

1999-01-01

Deformation mechanisms of fully lamellar TiAl with a refined microstructure (γ lamellae: 100 approximately 300 nm thick, α 2 lamellae: 10 approximately 50 nm thick) crept at 760 C have been investigated. As a result of a fine structure, the motion and multiplication of lattice dislocations within both γ and α 2 lamellae are limited at low creep stresses ( 2 and γ/γ interfaces (i.e., interface sliding) is proposed to be the dominant deformation mechanism at low stresses. Lattice dislocations impinged on lamellar interfaces are found to be the major obstacles impeding the motion of interfacial dislocations. The number of impinged lattice dislocations increases as the applied stress increases and, subsequently, causes the pileup of interfacial dislocations along the interfaces. Accordingly, deformation twinning activated by the pileup of interfacial dislocations is proposed to be the dominant deformation mechanism at high stresses (>400 MPa)

Evaluation of Biaxial Mechanical Properties of Aortic Media Based on the Lamellar Microstructure

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Hadi Taghizadeh

2015-01-01

Full Text Available Evaluation of the mechanical properties of arterial wall components is necessary for establishing a precise mechanical model applicable in various physiological and pathological conditions, such as remodeling. In this contribution, a new approach for the evaluation of the mechanical properties of aortic media accounting for the lamellar structure is proposed. We assumed aortic media to be composed of two sets of concentric layers, namely sheets of elastin (Layer I and interstitial layers composed of mostly collagen bundles, fine elastic fibers and smooth muscle cells (Layer II. Biaxial mechanical tests were carried out on human thoracic aortic samples, and histological staining was performed to distinguish wall lamellae for determining the dimensions of the layers. A neo-Hookean strain energy function (SEF for Layer I and a four-parameter exponential SEF for Layer II were allocated. Nonlinear regression was used to find the material parameters of the proposed microstructural model based on experimental data. The non-linear behavior of media layers confirmed the higher contribution of elastic tissue in lower strains and the gradual engagement of collagen fibers. The resulting model determines the nonlinear anisotropic behavior of aortic media through the lamellar microstructure and can be assistive in the study of wall remodeling due to alterations in lamellar structure during pathological conditions and aging.

On the mechanism of crack propagation resistance of fully lamellar TiAl alloy

International Nuclear Information System (INIS)

Cao, R.; Yao, H.J.; Chen, J.H.; Zhang, J.

2006-01-01

The study was done using notched two-colony thick tensile specimens of a directionally solidified cast fully lamellar TiAl alloy. In-situ observations of fracture processes in scanning electron microscope (SEM) were combined with section-to-section related observations of fracture surfaces to investigate the crack growth process. Finite element method (FEM) calculations are carried out to evaluate the stresses for propagating cracks. The results reveal that: (1) the reason why enhancement of applied load is required to propagate the main crack, was attributed to that the main crack observed at the surface did not extend all the way through the specimen's thickness thus the stress field was still controlled by the notch, in which a definite stress required for extending a crack tip should be kept by increasing the applied load. (2) Crack propagation resistance is enhanced at colony boundaries, only when a change occurs from an inter-lamellar propagation to a trans-lamellar propagation (3) Ligament bridging toughening phenomena can be integrated into aforementioned mechanism. As a whole the processes of new crack nucleation with bridging ligament formation decreases the crack propagation resistance rather than increasing it. (4) In case the majority of microcracks are surface cracks, the effect of microcrack shielding is not obvious

Mechanical contribution of lamellar and interlamellar elastin along the mouse aorta.

Science.gov (United States)

Clark, T E; Lillie, M A; Vogl, A W; Gosline, J M; Shadwick, R E

2015-10-15

The mechanical properties of aortic elastin vary regionally, but the microstructural basis for this variation is unknown. This study was designed to identify the relative contributions of lamellar and interlamellar elastin to circumferential load bearing in the mouse thoracic and abdominal aortas. Forces developed in uniaxial tests of samples of fresh and autoclaved aorta were correlated with elastin content and morphology obtained from histology and multiphoton laser scanning microscopy. Autoclaving should render much of the interlamellar elastin mechanically incompetent. In autoclaved tissue force per unit sample width correlated with lamellar elastin content (P≪0.001) but not total elastin content. In fresh tissue at low strain where elastin dominates the mechanical response, forces were higher than in the autoclaved tissue, but force did not correlate with total elastin content. Therefore although interlamellar elastin likely contributed to the stiffness in the fresh aorta, its contribution appeared not in proportion to its quantity. In both fresh and autoclaved tissue, elastin stiffness consistently decreased along the abdominal aorta, a key area for aneurysm development, and this difference could not be fully accounted for on the basis of either lamellar or total elastin content. These findings are relevant to the development of mathematical models of arterial mechanics, particularly for mouse models of arterial diseases involving elastic tissue. In microstructural based models the quantity of each mural constituent determines its contribution to the total response. This study shows elastin's mechanical response cannot necessarily be accounted for on the basis of fibre quantity, orientation, and modulus. Copyright © 2015 Elsevier Ltd. All rights reserved.

Fabrication and characterization of large size 6LiF/CaF2:Eu eutectic composites with the ordered lamellar structure

International Nuclear Information System (INIS)

Kawaguchi, Noriaki; Fukuda, Kentaro; Yanagida, Takayuki; Fujimoto, Yutaka; Yokota, Yuui; Suyama, Toshihisa; Watanabe, Kenichi; Yamazaki, Atsushi; Yoshikawa, Akira

2011-01-01

As alternative candidates for the 3 He neutron detectors, 6 LiF/CaF 2 :Eu eutectic composites were fabricated and their scintillation properties were evaluated. Large size LiF/CaF 2 :Eu eutectic composites of 58 mm diameter and 50 mm thickness were produced by Bridgman method. The composites had a finely ordered lamellar structure along the solidification direction. The lamellar structure was controlled by the direction and the rate of solidification, and it was optimized to improve the scintillation properties. Better results were achieved when thinner lamellar layers were aligned along the scintillation light path.

Role of surfactant-mediated electrodeposited titanium oxide substrate in improving electrocatalytic features of supported platinum particles

Energy Technology Data Exchange (ETDEWEB)

Spătaru, Tanţa; Preda, Loredana; Osiceanu, Petre; Munteanu, Cornel; Anastasescu, Mihai; Marcu, Maria; Spătaru, Nicolae, E-mail: nspataru@icf.ro

2014-01-01

A new hybrid system with improved photocatalytic and electrocatalytic performances was obtained by two-step potentiostatic deposition on highly boron-doped diamond (BDD) substrate. First, hydrated TiO{sub 2} was anodically deposited from a TiCl{sub 3} aqueous solution, both in the presence and in the absence of sodium dodecyl sulfate (SDS). The study of the UV irradiation effect evidenced that titanium oxide coatings obtained by surfactant-assisted electrodeposition (TiO{sub 2}:SDS) exhibit enhanced photocurrent, due to its very rough texonsture and presumably to better efficiency of charge carrier separation. Electrochemical deposition of platinum on the oxide-coated BDD was carried out in a second step and AFM, SEM and XPS measurements have shown that, on the TiO{sub 2}:SDS substrate, Pt particles are smaller, more uniformly distributed, and tend to form clusters, leading to a specific surface area of the electrocatalyst of ca. 6.55 m{sup 2} g{sup −1}. Carbon monoxide stripping experiments demonstrated that, when deposited on TiO{sub 2}:SDS, Pt particles are also less sensitive to CO-poisoning during methanol anodic oxidation.

Growth crystallography and lamellar to rod transition in directionally solidified Nb--Nb2C eutectic composites

International Nuclear Information System (INIS)

David, S.A.; Santhanam, A.T.; Brody, H.D.

1976-01-01

The transition in morphology of the carbide phase is discussed in terms of the relative volume fraction of the phases, growth rate, and orientation relationships. The carbide morphology is influenced by the growth rate and carbon content. For constant growth rate increasing the volume fraction of the carbide phase favors the lamellar morphology. At low growth rates the lamellar morphology is favored, and at high growth rates the rod-like morphology is favored. Growth crystallography has no direct influence on the transition in carbide morphology

Analytic theory of soft x-ray diffraction by lamellar multilayer gratings

NARCIS (Netherlands)

Kozhevnikov, I.V.; van der Meer, R.; Bastiaens, Hubertus M.J.; Boller, Klaus J.; Bijkerk, Frederik

2011-01-01

An analytic theory describing soft x-ray diffraction by Lamellar Multilayer Gratings (LMG) has been developed. The theory is derived from a coupled waves approach for LMGs operating in the single-order regime, where an incident plane wave can only excite a single diffraction order. The results from

Inverse cutting of posterior lamellar corneal grafts by a femtosecond laser

DEFF Research Database (Denmark)

Hjortdal, Jesper; Nielsen, Esben; Vestergaard, Anders Højslet

2012-01-01

(range: 1.400 to 2.000 cells per sq. mm). The grafts were of uniform thickness, but substantial interface haze was present in most grafts. Conclusions: Posterior lamellar corneal grafts can be prepared from the endothelial side using a femto-second laser. All grafts were clear after 6 months...

Chain elongation suppression of cyclic block copolymers in lamellar microphase-separated bulk

NARCIS (Netherlands)

Matsushita, Y; Iwata, H; Asari, T; Uchida, T; ten Brinke, G; Takano, A

2004-01-01

Chain elongation suppression of cyclic block copolymers in microphase-separated bulk was determined quantitatively. Solvent-cast and annealed films are confirmed to show alternating lamellar structure and their microdomain spacing D increases with increasing total molecular weight M according to the

Polynomial modal analysis of lamellar diffraction gratings in conical mounting.

Science.gov (United States)

Randriamihaja, Manjakavola Honore; Granet, Gérard; Edee, Kofi; Raniriharinosy, Karyl

2016-09-01

An efficient numerical modal method for modeling a lamellar grating in conical mounting is presented. Within each region of the grating, the electromagnetic field is expanded onto Legendre polynomials, which allows us to enforce in an exact manner the boundary conditions that determine the eigensolutions. Our code is successfully validated by comparison with results obtained with the analytical modal method.

Lamellar Micelles - Mediated Synthesis of Nanoscale Thick Sheets of Titania

Czech Academy of Sciences Publication Activity Database

Klusoň, P.; Lusková, H.; Šolcová, Olga; Matějová, Lenka; Cajthaml, Tomáš

2007-01-01

Roč. 61, 14-15 (2007), s. 2931-2934 ISSN 0167-577X R&D Projects: GA ČR(CZ) GA104/04/0963; GA ČR(CZ) GD203/03/H140 Institutional research plan: CEZ:AV0Z40720504; CEZ:AV0Z50200510 Keywords : nanostructures * lamellar titania * templating Subject RIV: CA - Inorganic Chemistry Impact factor: 1.625, year: 2007

Phase-field-lattice Boltzmann study for lamellar eutectic growth in a natural convection melt

Directory of Open Access Journals (Sweden)

Ang Zhang

2017-11-01

Full Text Available In the present study, the influence of natural convection on the lamellar eutectic growth is determined by a phase-field-lattice Boltzmann study for Al-Cu eutectic alloy. The mass difference resulting from concentration difference led to the fluid flow, and a robust parallel and adaptive mesh refinement algorithm was employed to improve the computational efficiency without any compromising accuracy. Results show that the existence of natural convection would affect the growth undercooling and thus control the interface shape by adjusting the lamellar width. In particular, by alternating the magnitude of the solute expansion coefficient, the strength of the natural convection is changed. Corresponding microstructure patterns are discussed and compared with those under no-convection conditions.

LAMELLAR ICHTHYOSIS (COLLODION BABY

Directory of Open Access Journals (Sweden)

Paramarta IGE

2012-11-01

Full Text Available The ichthyosis are a heterogeneous group of hereditary and acquired disorder of keratinization which affected the epidermis characterized by presence of visible scales on the skin surface in the absence of inflammation. It can occur as a disease limited to the skin or in association with abnormalities of other organ systems. Lamelar ihthyosis (LI is one of two mayor autosomal recessive ichthyosis with an incidence of approximately one in 300,000. The diagnosis is based on clinical and pathologic finding. Infection is the most common complication, while prognosis of LI is depends on severity and complication of the disease. A case of lamellar ichthyosis in 0 day Balinese female baby was reported. The skin of the body was thick, plate-like appearance, scaling on the entire body, some of the thick skin was ruptured on chest and extremities. There were eclabium on the mouth and ectropion on the eyes. Histopathology examination showed hyperkeratosis without perivascular infiltration lymphocyte. The baby was given breast feeding, antibiotic, hydrocortisone cream and olium olivarum. The prognosis of the baby is good.

Fourier method for modeling slanted lamellar gratings of arbitrary end-surface shapes in conical mounting.

Science.gov (United States)

Li, Lifeng

2015-10-01

An efficient modal method for numerically modeling slanted lamellar gratings of isotropic dielectric or metallic media in conical mounting is presented. No restrictions are imposed on the slant angle and the length of the lamellae. The end surface of the lamellae can be arbitrary, subject to certain restrictions. An oblique coordinate system that is adapted to the slanted lamella sidewalls allows the most efficient way of representing and manipulating the electromagnetic fields. A translational coordinate system that is based on the oblique Cartesian coordinate system adapts to the end-surface profile of the lamellae, so that the latter can be handled simply and easily. Moreover, two matrix eigenvalue problems of size 2N × 2N, one for each fundamental polarization of the electromagnetic fields in the periodic lamellar structure, where N is the matrix truncation number, are derived to replace the 4N × 4N eigenvalue problem that has been used in the literature. The core idea leading to this success is the polarization decomposition of the electromagnetic fields inside the periodic lamellar region when the fields are expressed in the oblique translational coordinate system.

Precipitation of lamellar gold nanocrystals in molten polymers

International Nuclear Information System (INIS)

Palomba, M.; Carotenuto, G.

2016-01-01

Non-aggregated lamellar gold crystals with regular shape (triangles, squares, pentagons, etc.) have been produced by thermal decomposition of gold chloride (AuCl) molecules in molten amorphous polymers (polystyrene and poly(methyl methacrylate)). Such covalent inorganic gold salt is high soluble into non-polar polymers and it thermally decomposes at temperatures compatible with the polymer thermal stability, producing gold atoms and chlorine radicals. At the end of the gold precipitation process, the polymer matrix resulted chemically modified because of the partial cross-linking process due to the gold atom formation reaction.

Excimer laser-assisted anterior lamellar keratoplasty for keratoconus, corneal problems after laser in situ keratomileusis, and corneal stromal opacities.

Science.gov (United States)

Bilgihan, Kamil; Ozdek, Sengül C; Sari, Ayça; Hasanreisoğlu, Berati

2006-08-01

To evaluate excimer laser-assisted anterior lamellar keratoplasty to augment thin corneas as in keratoconus ( .05). This technique presents a different modality for the treatment of keratoconus, post-LASIK corneal problems, and other corneal stromal opacities with anterior lamellar keratoplasty. Additional studies with more patients and longer follow-up will help determine the role of this technique as a substitute for penetrating keratoplasty in these patients.

Three-dimensional structure of human lamellar bone: the presence of two different materials and new insights into the hierarchical organization.

Science.gov (United States)

Reznikov, Natalie; Shahar, Ron; Weiner, Steve

2014-02-01

Lamellar bone is the most common bone type in humans. The predominant components of individual lamellae are plywood-like arrays of mineralized collagen fibrils aligned in different directions. Using a dual-beam electron microscope and the Serial Surface View (SSV) method we previously identified a small, but significantly different layer in rat lamellar bone, namely a disordered layer with collagen fibrils showing little or no preferred orientation. Here we present a 3D structural analysis of 12 SSV volumes (25 complete lamellae) from femora of 3 differently aged human individuals. We identify the ordered and disordered motifs in human bone as in the rat, with several significant differences. The ordered motif shows two major preferred orientations, perpendicular to the long axis of the bone, and aligned within 10-20° of the long axis, as well as fanning arrays. At a higher organizational level, arrays of ordered collagen fibrils are organized into 'rods' around 2 to 3μm in diameter, and the long axes of these 'rods' are parallel to the lamellar boundaries. Human bone also contains a disordered component that envelopes the rods and fills in the spaces between them. The disordered motif is especially well-defined between adjacent layers of rods. The disordered motif and its interfibrillar substance stain heavily with osmium tetroxide and Alcian blue indicating the presence of another organic component in addition to collagen. The canalicular network is confined to the disordered material, along with voids and individual collagen fibrils, some of which are also aligned more or less perpendicular to the lamellar boundaries. The organization of the ordered fibril arrays into rods enveloped in the continuous disordered structure was not observed in rat lamellar bone. We thus conclude that human lamellar bone is comprised of two distinct materials, an ordered material and a disordered material, and contains an additional hierarchical level of organization composed of

Oral manifestations of lamellar ichthyosis: A rare case report

Directory of Open Access Journals (Sweden)

Keerthi K Nair

2016-01-01

Full Text Available The ichthyoses are a heterogeneous group of disorders with both inherited and acquired forms. Autosomal recessive congenital ichthyosis (ARCI is a heterogeneous group of disorders that present at birth with the generalized involvement of skin without other systemic manifestations. Lamellar itchthyosis (LI is a nonsyndromic itchthyosis, which comes under the umbrella of ARCI. Little is only known about the oral manifestations of this disorder. We report a case of LI with oral manifestations.

A novel ethanol templating synthesis of ordered lamellar superstructured crystalline zirconia

International Nuclear Information System (INIS)

Liu Chao; Wang Bin; Ji Xiujie; Zhao Shanshan; Wu Jie; Jia Jianlong; Ma Dongxia

2012-01-01

Soft template technique has attracted great interest, because it is a facile, inexpensive and efficient synthesis strategy for ordered superstructural systems. Here, a novel ethanol template was used to synthesize the ordered lamellar superstructured crystalline zirconia (Lα-ZrO 2 ) without post-treatments and surfactants. ZrOCl 2 and NaOH were served as Zr source and precipitant, respectively. XRD analysis showed that Lα-ZrO 2 is crystalline. XPS spectra indicated the physical adsorption of ethanol molecules in Lα-ZrO 2 . TEM further observed and proved the 1.36-nm period of superstructure detected and calculated by SAXRD (1.35 nm), which is composed of 0.68-nm thick ZrO 2 and pore alternatively. In contrast, the template-free ZrO 2 (TF-ZrO 2 ) presents no superstructure and is poorly crystallized. As a soft template, ethanol presents the roles of (i) inducing the growth of zirconia layers, (ii) directing the self-assembly of ordered lamellar superstructure, and (iii) decreasing the crystallization temperature. The possible mechanism of ethanol serving as a soft template was proposed and discussed in thermodynamics.

Closed compact Taylor's droplets in a phase-separated lamellar-sponge mixture under shear flow

Science.gov (United States)

Courbin, L.; Cristobal, G.; Rouch, J.; Panizza, P.

2001-09-01

We have studied by optical microscopy, small-angle light scattering, and rheology, the behavior under shear flow of a phase-separated lamellar-sponge (Lα - L3) ternary mixture. We observe in the Lα-rich region (ΦLα > 80%) the existence of a Newtonian assembly made of closed compact monodisperse lamellar droplets immersed in the sponge phase. Contrary to the classical onion glassy texture obtained upon shearing Lα phases, the droplet size scales herein as dot gamma-1, the inverse of the shear rate. This result is in good agreement with Taylor's picture. Above a critical shear rate, dot gammac, the droplets organize to form a single colloidal crystal whose lattice size varies as dot gamma-1/3. To the memory of Tess Melissa P.

A Study of the Confinement Induced Sponge to Lamellar Phase Transformation by Direct Force Measurement

International Nuclear Information System (INIS)

Antelmi, David

1996-10-01

The interactions between two macroscopic walls immersed in an isotropic symmetric sponge phase (L_3) at different volume fractions, Φ, were studied with a surface force apparatus. The purpose of these experiments was to investigate the behaviour of the sponge phase when confined between two smooth rigid surfaces. Particular attention was given to investigating this behaviour as the bulk transition to the lamellar phase (L_α) was approached. At temperatures far from the L_3/L_α bulk transition temperature, the force-distance profile showed weak oscillations with a periodicity approximately equal to twice the characteristic length, ξ, measured for the sponge phase from small angle x-ray scattering. Furthermore, the oscillations were superimposed on an exponential attractive background that decayed with an order parameter correlation length of 2-3 times ξ The attractive background was explained by the enhancement of the sponge order in the vicinity of the rigid walls. The structural oscillations observed in the force-distance profile, although not completely understood, were discussed in terms of the packing of sponge cells (cell size ξ). The significance of the observed periodicity (2ξ) may indicate the importance of the symmetric nature of the sponge phase. By moving pairs of cells in response to an applied strain, the symmetry of the sponge structure is protected. As the temperature increased towards the L_3/L_α bulk transition temperature, an abrupt change in the force-distance profile was observed at a threshold separation labelled D*_i_n. A different force regime was observed for separations below D*_i_n which oscillated with a periodicity that was twice the reticular spacing, d, for a L_α phase of similar Φ. The force oscillations were superimposed on an attractive background that was almost linear. These observations were consistent with a first order phase transition from the sponge phase to the lamellar phase, induced by the confinement, where the

Self-consistent theory of steady-state lamellar solidification in binary eutectic systems

International Nuclear Information System (INIS)

Nash, G.E.; Glicksman, M.E.

1976-01-01

The potential theoretic methods developed recently at NRL for solving the diffusion equation are applied to the free-boundary problem describing lamellar eutectic solidification. Using these techniques, the original boundary value problem is reduced to a set of coupled integro-differential equations for the shape of the solid/liquid interface and various quantities defined on the interface. The behavior of the solutions is discussed in a qualitative fashion, leading to some interesting inferences regarding the nature of the eutectic solidification process. Using the information obtained from the analysis referred to above, an approximate theory of the lamellar-rod transition is formulated. The predictions of the theory are shown to be in qualitative agreement with experimental observations of this transition. In addition, a simplified version of the general integro-differential equations is developed and is used to assess the effect of interface curvature on the interfacial solute concentrations, and to check the new theory for consistency with experiment

Evaluation of Microemulsion and Lamellar Liquid Crystalline Systems for Transdermal Zidovudine Delivery.

Science.gov (United States)

Carvalho, André Luis Menezes; Silva, José Alexsandro da; Lira, Ana Amélia Moreira; Conceição, Tamara Matos Freire; Nunes, Rogéria de Souza; de Albuquerque Junior, Ricardo Luiz Cavalcanti; Sarmento, Victor Hugo Vitorino; Leal, Leila Bastos; de Santana, Davi Pereira

2016-07-01

This study proposed to investigate and to compare colloidal carrier systems containing Zidovudine (3'-azido-3'-deoxythymidine) (AZT) for transdermal administration and optimization of antiretroviral therapy. Microemulsion (ME) and lamellar phase (LP) liquid crystal were obtained and selected from pseudoternary diagrams previously developed. Small-angle X-ray scattering and rheology analysis confirmed the presence of typical ME and liquid crystalline structures with lamellar arrangement, respectively. Both colloidal carrier systems, ME, and LP remained stable, homogeneous, and isotropic after AZT addition. In vitro permeation study (using pig ear skin) showed that the amount of permeated drug was higher for ME compared to the control and LP, obtaining a permeation enhancing effect on the order of approximately 2-fold (p drug permeation without causing apparent skin irritation. On the order hand, LP functioned as a drug reservoir reducing AZT partitioning into the skin. Copyright © 2016 American Pharmacists Association®. Published by Elsevier Inc. All rights reserved.

Fabrication and characterization of large size {sup 6}LiF/CaF{sub 2}:Eu eutectic composites with the ordered lamellar structure

Energy Technology Data Exchange (ETDEWEB)

Kawaguchi, Noriaki [Tokuyama Corporation, 3-3-1 Shibuya, Shibuya-ku, Tokyo 150-8383 (Japan); Fukuda, Kentaro, E-mail: ken-fukuda@tokuyama.co.jp [Tokuyama Corporation, 3-3-1 Shibuya, Shibuya-ku, Tokyo 150-8383 (Japan); Yanagida, Takayuki; Fujimoto, Yutaka; Yokota, Yuui [Institute of Multidisciplinary Research for Advanced Materials, Tohoku University, 2-1-1 Katahira, Aoba-ku, Sendai, Miyagi 980-8577 (Japan); Suyama, Toshihisa [Tokuyama Corporation, 3-3-1 Shibuya, Shibuya-ku, Tokyo 150-8383 (Japan); Watanabe, Kenichi; Yamazaki, Atsushi [Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-8603 (Japan); Yoshikawa, Akira [Institute of Multidisciplinary Research for Advanced Materials, Tohoku University, 2-1-1 Katahira, Aoba-ku, Sendai, Miyagi 980-8577 (Japan); New Industry Creation Hatchery Center, Tohoku University, 6-6-10 Aoba, Aramaki, Aoba-ku, Sendai 980-8579 (Japan)

2011-10-01

As alternative candidates for the {sup 3}He neutron detectors, {sup 6}LiF/CaF{sub 2}:Eu eutectic composites were fabricated and their scintillation properties were evaluated. Large size LiF/CaF{sub 2}:Eu eutectic composites of 58 mm diameter and 50 mm thickness were produced by Bridgman method. The composites had a finely ordered lamellar structure along the solidification direction. The lamellar structure was controlled by the direction and the rate of solidification, and it was optimized to improve the scintillation properties. Better results were achieved when thinner lamellar layers were aligned along the scintillation light path.

Substrate system for spray forming

Energy Technology Data Exchange (ETDEWEB)

Chu, Men G. (Export, PA); Chernicoff, William P. (Harrisburg, PA)

2002-01-01

A substrate system for receiving a deposit of sprayed metal droplets including a movable outer substrate on which the sprayed metal droplets are deposited. The substrate system also includes an inner substrate disposed adjacent the outer substrate where the sprayed metal droplets are deposited on the outer substrate. The inner substrate includes zones of differing thermal conductivity to resist substrate layer porosity and to resist formation of large grains and coarse constituent particles in a bulk layer of the metal droplets which have accumulated on the outer substrate. A spray forming apparatus and associated method of spray forming a molten metal to form a metal product using the substrate system of the invention is also provided.

High Momentum Particle Identification Detector The Study of Cesium Iodide Quantum Efficiency Dependency on Substrate Material, Temperature and Quartz Window

CERN Document Server

Wisna, Gde Bimananda M

2014-01-01

The Cesium Iodide (CsI) is used as a material for detecting Cherenkov radiation produced by high momentum particle in High Momentum Particle Identification Detector (HMPID) at ALICE Experiment at CERN. This work provides investigation and analysis of The Quantum Efficiency (QE) result of CsI which is deposited on five samples substrates such as copper passivated red, copper passivated yellow, aluminium, copper coated with nickel and copper coated with nickel then coated with gold. The measurement of five samples is held under temperature $60^{0}$ C and $25^{0}$ C (room temperature) and also with optical quartz window which can be adjusted to limit the wavelength range which reach the CsI. The result shows there are dependency of substrate, temperature due to enhancement effect and also quartz windows usage on QE of CsI. The results of five samples is then compared and analyzed.

Comparison of synthetic glues and 10-0 nylon in rabbit lamellar keratoplasty.

Science.gov (United States)

Cho, Soon Young; Kim, Man Soo; Oh, Su Ja; Chung, Sung Kun

2013-09-01

To evaluate changes in mean keratometry and to compare wound repair with corneal lamellar grafts in rabbit eyes using human synthetic tissue adhesives and 10-0 nylon. Corneal grafts were made using a 6.0-mm-diameter trephine and blades in the eyes of 15 New Zealand white rabbits. Human fibrin tissue adhesive (Tisseel) was used in group 1, human fibrin tissue adhesive (Beriplast P) was used in group 2, polyethylene glycol adhesive (Coseal) was used in group 3, and 8 bite sutures with 10-0 nylon were used in group 4 (control) for lamellar keratoplasty. Four bite sutures were made with 10-0 nylon in groups 1, 2, and 3. Slit-lamp microscopy and keratometry were performed at 3 days and 1, 2, and 4 weeks after the surgery. Histopathologic and electromicroscopic examinations were performed 4 weeks after the surgery. No inflammation or corneal toxicity was seen in groups 1 and 2. Histologically, a few inflammatory cells were seen in groups 3 and 4. Groups 1, 2, and 3 showed no statistically significant changes in mean keratometry at 4 weeks postoperatively compared with preoperative mean keratometry (Wilcoxon signed-rank test, P = 0.178, 0.208, and 0.889, respectively). The control group showed significant changes in mean keratometry at 4 weeks postoperatively (Wilcoxon signed-rank test, P = 0.018). Human fibrin tissue adhesives were well tolerated in rabbit eyes, with no apparent corneal toxicity. Polyethylene glycol adhesive showed more inflammation and insufficient wound repair compared with human fibrin tissue adhesives. Therefore, human fibrin tissue adhesives can be used as an alternative to sutures in lamellar keratoplasty.

The color tuning of PS-b-P2VP lamellar films with changing the alkyl chain length of 1-iodoalkanes.

Science.gov (United States)

Shin, Sung-Eui; Kim, Su-Young; Shin, Dong-Myung

2011-05-01

Photonic crystals with tunability in the visible or near-infrared region have drawn increasing attention for controlling and processing light for the active components of future display. We prepared polystyrene-b-poly(2-vinyl pyridine) (PS-b-P2VP) lamellar films which is hydrophobic block-hydrophilic polyelectrolyte block polymer of 57 kg/mol-b-57 kg/mol. The lamellar stacks, which is alternating layer of hydrophilic and hydrophobic moiety of PS-b-P2VP, are obtained by exposing the spin coated film under chloroform vapor. The band gaps of the lamellar films interestingly varied after immersion into the quaternizing solvents containing 5 wt% of iodomethane, iodoethane, 1-iodobutane, 1-iodopentane, 1-iodohexane and 1-iodooctane solubilized in n-hexane. The iodoalkanes reacted with pyridine groups in PS-b-P2VP and generated the alkyl pyridinium salts readily. The degree of quaternization, alkyl chain length of iodoalkane and the salt water concentration affects the spacing of layer structure of PS-b-P2VP. The iodomethane and iodohexane produced similar band gaps and salt concentration dependence. These results are very much dependent on the hydrophobic-hydrophilic characters of PS-b-P2VP lamellar surface.

Lamellar Microdomains of Block-Copolymer-Based Ionic Supramolecules Exhibiting a Hierarchical Self-Assembly

DEFF Research Database (Denmark)

Ayoubi, Mehran Asad; Almdal, Kristoffer; Zhu, Kaizheng

2014-01-01

(Cn; n = 8, 12, and 16) trimethylammonium counterions (i.e., side chains) at various ion (pair) fractions X [i.e., counterion/side-chain grafting density; X = number of alkyl counterions (i.e., side chains) per acidic group of the parent PMAA block] these L-b-AC ionic supramolecules exhibit...... a spherical-in-lamellar hierarchical self-assembly. For these systems, (1) the effective Flory-Huggins interaction parameter between L- and AC-blocks chi'(Cn/x) was extracted, and (2) analysis of the lamellar microdomains showed that when there is an increase in X, alkyl counterion (i.e., side chain) length l......Based on a parent diblock copolymer of poly(styrene)-b-poly(methacrylic acid), PS-b-PMAA, linear-b-amphiphilic comb (L-b-AC) ionic supramolecules [Soft Matter 2013, 9, 1540-1555] are synthesized in which the poly(methacrylate) backbone of the ionic supramolecular AC-block is neutralized by alkyl...

Modelling, characterization, and development of new photovoltaic devices on thin silicon substrates; Modelisation, caracterisation et realisation de nouvelles structures photovoltaiques sur substrat de silicium mince

Energy Technology Data Exchange (ETDEWEB)

Veschetti, Y.

2005-10-15

Thermal barrier coatings are used to protect parts from heat. They are generally composed of two layers, one metallic layer providing heat corrosion and oxidation resistance, and one thermally insulating ceramic layer. Two different techniques are industrially used. Plasma spray results in a lamellar structure granting a low thermal conductivity, but with a low thermal expansion compliance. Electron Beam Physical Vapour Deposition generates a columnar structure allowing a better accommodation of the thermal expansion stresses, entailing a improved lifetime of the coating, but with a higher thermal conductivity. The aim of this work is the generation of macro-cracked plasma sprayed coatings made in one thick pass, in order to improve part lifetime. These coatings result from an important through the coating thermal gradient during deposition, entailing such a stress level that macro-cracks are generated. The control of the crack density is possible by adjusting the spray parameters. The coatings exhibit a three-zone structure: lamellae neighbouring the bond coat, a columnar central part resulting from the zirconia liquid bath solidification, and a mixed lamellar columnar zone coming from the piling up of the droplets travelling in the periphery of the particle jet. (author)

Electron microscopy of atmospheric particles

Science.gov (United States)

Huang, Po-Fu

Electron microscopy coupled with energy dispersive spectrometry (EM/EDS) is a powerful tool for single particle analysis. However, the accuracy with which atmospheric particle compositions can be quantitatively determined by EDS is often hampered by substrate-particle interactions, volatilization losses in the low pressure microscope chamber, electron beam irradiation and use of inaccurate quantitation factors. A pseudo-analytical solution was derived to calculate the temperature rise due to the dissipation of the electron energy on a particle-substrate system. Evaporative mass loss for a spherical cap-shaped sulfuric acid particle resting on a thin film supported by a TEM grid during electron beam impingement has been studied. Measured volatilization rates were found to be in very good agreement with theoretical predictions. The method proposed can also be used to estimate the vapor pressure of a species by measuring the decay of X-ray intensities. Several types of substrates were studied. We found that silver-coated silicon monoxide substrates give carbon detection limits comparable to commercially available substrates. An advantage of these substrates is that the high thermal conductivity of the silver reduces heating due to electron beam impingement. In addition, exposure of sulfuric acid samples to ammonia overnight substantially reduces sulfur loss in the electron beam. Use of size-dependent k-factors determined from particles of known compositions shows promise for improving the accuracy of atmospheric particle compositions measured by EM/EDS. Knowledge accumulated during the course of this thesis has been used to analyze atmospheric particles (Minneapolis, MN) selected by the TDMA and collected by an aerodynamic focusing impactor. 'Less' hygroscopic particles, which do not grow to any measurable extent when humidified to ~90% relative humidity, included chain agglomerates, spheres, flakes, and irregular shapes. Carbon was the predominant element detected in

A novel ethanol templating synthesis of ordered lamellar superstructured crystalline zirconia

Energy Technology Data Exchange (ETDEWEB)

Liu Chao, E-mail: liuchao_tj@yahoo.com; Wang Bin [Key Laboratory for New Type of Functional Materials in Hebei Province, Hebei University of Technology (China); Ji Xiujie, E-mail: jxjchem@yahoo.com [State Key Laboratory of Hollow Fiber Membrane Materials and Processes, Tianjin Polytechnic University (China); Zhao Shanshan; Wu Jie; Jia Jianlong; Ma Dongxia [Key Laboratory for New Type of Functional Materials in Hebei Province, Hebei University of Technology (China)

2012-03-15

Soft template technique has attracted great interest, because it is a facile, inexpensive and efficient synthesis strategy for ordered superstructural systems. Here, a novel ethanol template was used to synthesize the ordered lamellar superstructured crystalline zirconia (L{alpha}-ZrO{sub 2}) without post-treatments and surfactants. ZrOCl{sub 2} and NaOH were served as Zr source and precipitant, respectively. XRD analysis showed that L{alpha}-ZrO{sub 2} is crystalline. XPS spectra indicated the physical adsorption of ethanol molecules in L{alpha}-ZrO{sub 2}. TEM further observed and proved the 1.36-nm period of superstructure detected and calculated by SAXRD (1.35 nm), which is composed of 0.68-nm thick ZrO{sub 2} and pore alternatively. In contrast, the template-free ZrO{sub 2} (TF-ZrO{sub 2}) presents no superstructure and is poorly crystallized. As a soft template, ethanol presents the roles of (i) inducing the growth of zirconia layers, (ii) directing the self-assembly of ordered lamellar superstructure, and (iii) decreasing the crystallization temperature. The possible mechanism of ethanol serving as a soft template was proposed and discussed in thermodynamics.

Dusty-Plasma Particle Accelerator

Science.gov (United States)

Foster, John E.

2005-01-01

A dusty-plasma apparatus is being investigated as means of accelerating nanometer- and micrometer-sized particles. Applications for the dusty-plasma particle accelerators fall into two classes: Simulation of a variety of rapidly moving dust particles and micrometeoroids in outer-space environments that include micrometeoroid streams, comet tails, planetary rings, and nebulae and Deposition or implantation of nanoparticles on substrates for diverse industrial purposes that could include hardening, increasing thermal insulation, altering optical properties, and/or increasing permittivities of substrate materials. Relative to prior apparatuses used for similar applications, dusty-plasma particle accelerators offer such potential advantages as smaller size, lower cost, less complexity, and increased particle flux densities. A dusty-plasma particle accelerator exploits the fact that an isolated particle immersed in plasma acquires a net electric charge that depends on the relative mobilities of electrons and ions. Typically, a particle that is immersed in a low-temperature, partially ionized gas, wherein the average kinetic energy of electrons exceeds that of ions, causes the particle to become negatively charged. The particle can then be accelerated by applying an appropriate electric field. A dusty-plasma particle accelerator (see figure) includes a plasma source such as a radio-frequency induction discharge apparatus containing (1) a shallow cup with a biasable electrode to hold the particles to be accelerated and (2) a holder for the substrate on which the particles are to impinge. Depending on the specific design, a pair of electrostatic-acceleration grids between the substrate and discharge plasma can be used to both collimate and further accelerate particles exiting the particle holder. Once exposed to the discharge plasma, the particles in the cup quickly acquire a negative charge. Application of a negative voltage pulse to the biasable electrode results in the

Lamellar zirconium phosphates to host metals for catalytic purposes.

Science.gov (United States)

Ballesteros-Plata, Daniel; Infantes-Molina, Antonia; Rodríguez-Aguado, Elena; Braos-García, Pilar; Rodríguez-Castellón, Enrique

2018-02-27

In the present study a porous lamellar zirconium phosphate heterostructure (PPH) formed from zirconium(iv) phosphate expanded with silica galleries (P/Zr molar ratio equal to 2 and (Si + Zr)/P equal to 3) was prepared to host noble metals. Textural and structural characterization of PPH-noble metal materials was carried out in order to elucidate the location and dispersion of the metallic particles and the properties of the resulting material to be used in catalytic processes. In the present paper, their activity in the catalytic hydrodeoxygenation (HDO) reaction of dibenzofuran (DBF) was evaluated. X-ray diffraction (XRD), solid state nuclear magnetic resonance (NMR) and X-ray photoelectron spectroscopy (XPS) evidenced that the structure of the pillared zirconium phosphate material was not modified by the incorporation of Pt and Pd. Moreover, transmission electron microscopy (TEM) showed a different dispersion of the noble metal. The acidity of the resulting PPH-noble metal materials also changed, although in all cases the acidity was of weak nature, and the incorporation of noble metals affected Brønsted acid sites as observed from 31 P NMR spectra. In general, the textural, structural and acidic properties of the resulting materials suggest that PPH can be considered a good candidate to be used as a catalytic support. Thus, the catalytic results of the PPH-noble metal samples indicated that the Pd sample showed a stable behavior probably ascribed to a high dispersion of the active phase. However, the Pt sample suffered from fast deactivation. The selectivity to the reaction products was strongly dependent on the noble metal employed.

Numerical modelling of adsorption of metallic particles on graphite substrate via molecular dynamics simulation

International Nuclear Information System (INIS)

Rafii-Tabar, H.

1998-01-01

A computer-based numerical modelling of the adsorption process of gas phase metallic particles on the surface of a graphite substrate has been performed via the application of molecular dynamics simulation method. The simulation related to an extensive STM-based experiment performed in this field, and reproduces part of the experimental results. Both two-body and many-body inter-atomic potentials have been employed. A Morse-type potential describing the metal-carbon interactions at the interface was specially formulated for this modelling. Intercalation of silver in graphite has been observed as well as the correct alignments of monomers, dimers and two-dimensional islands on the surface. (author)

In situ growth of lamellar ZnTiO3 nanosheets on TiO2 tubular array with enhanced photocatalytic activity.

Science.gov (United States)

Cai, Yunyu; Ye, Yixing; Tian, Zhenfei; Liu, Jun; Liu, Yishu; Liang, Changhao

2013-12-14

We report a self-sacrificed in situ growth design toward preparation of ZnTiO3-TiO2 heterojunction structure. Highly reactive zinc oxide colloidal particles derived by laser ablation in liquids can react with TiO2 nanotubes to form a lamellar ZnTiO3 nanosheet structure in a hydrothermal-treatment process. Such hybrid structural product was characterized by X-ray diffraction, scanning and transmission electron microscopy, UV-vis diffuse reflection spectroscopy and X-ray photoelectron spectroscopy. The enhanced photocatalytic activity of the hybrid structure toward degradation of methyl orange (MO) and pentachlorophenol (PCP) molecules was demonstrated and compared with single phase TiO2, as a result of the efficient separation of light excited electrons and holes at the hetero-interfaces in the two semiconductors.

Multiscale Simulations of Lamellar PS–PEO Block Copolymers Doped with LiPF6 Ions

KAUST Repository

Sethuraman, Vaidyanathan; Mogurampelly, Santosh; Ganesan, Venkat

2017-01-01

We report the results of atomistic simulations of the structural equilibrium properties of PS–PEO block copolymer (BCP) melt in the ordered lamellar phase doped with LiPF6 salt. A hybrid simulation strategy, consisting of steps of coarse

Method for coating substrates and mask holder

NARCIS (Netherlands)

Bijkerk, Frederik; Yakshin, Andrey; Louis, Eric; Kessels, M.J.H.; Maas, Edward Lambertus Gerardus; Bruineman, Caspar

2004-01-01

When coating substrates it is frequently desired that the layer thickness should be a certain function of the position on the substrate to be coated. To control the layer thickness a mask is conventionally arranged between the coating particle source and the substrate. This leads to undesirable

Intense luminescence emission from rare-earth-doped MoO3 nanoplates and lamellar crystals for optoelectronic applications

International Nuclear Information System (INIS)

Vila, M; Díaz-Guerra, C; Jerez, D; Piqueras, J; Lorenz, K; Alves, E

2014-01-01

Strong and stable room-temperature photoluminescence (PL) emission is achieved in MoO 3 nanoplates and lamellar crystals doped with Er and Eu by ion implantation and subsequent annealing. Micro-Raman and PL spectroscopy reveal that optical activation of the rare earth ions and recovery of the original MoO 3 structure are achieved for shorter annealing treatments and for lower temperatures in nanoplates, as compared with lamellar crystals. Er seems to be more readily incorporated into optically active sites in the oxide lattice than Eu. The influence of the dimensionality of the host sample on the characteristics of the PL emission of both rare earth dopants is addressed. (paper)

Alumina particle degradation during solid particle impact on glass

NARCIS (Netherlands)

Slikkerveer, P.J.; Veld, in 't H.; Verspui, M.A.; With, de G.; Reefman, D.

2000-01-01

Particle degradation limits the reuse of powders in industrial powder-blast processes. In this paper the degradation behavior of Al2O3 powder is studied during erosion of glass substrates. Three techniques were used on original and multiply used powders: particle size measurements, single particle

Using Ice Nucleating Particles to Enable Desublimation on Chilled Substrates

Science.gov (United States)

O'Brien, Julia; Failor, Kevin; Bisbano, Caitlin; Mulroe, Megan; Nath, Saurabh; Vinatzer, Boris; Boreyko, Jonathan

2017-11-01

On a subfreezing surface, nucleating embryos usually form as supercooled condensate that later freeze into ice, as opposed to desublimation. Ice nucleating particles (INPs) have been widely used to freeze existing water; however, nobody has studied how they might affect the initial mode of nucleation. Here, we show that INPs deposited on a substrate can switch the mode of embryo nucleation to desublimation, rather than supercooled condensation. Deposition was achieved by evaporating a water droplet containing INPs on a hydrophobic silicon wafer. A Peltier stage was used to cool the wafer down inside of a controlled humidity chamber, such that the desired set point temperature correlated with the dew point and onset of nucleation. Beneath a critical surface temperature, microscopy indicated that desublimation occurred on the circular patch of deposited INPs, compared to supercooled condensation outside the circle. The hydrophobic surface was then patterned with hydrophilic stripe arrays, which facilitated the deposition of stripes of INPs via the same evaporation method. The resulting array of desublimating ice stripes created dry zones free of condensation or frost in the intermediate areas, as the hygroscopic ice stripes served as overlapping humidity sinks.

Biosensors based on directed assembly of particles

Science.gov (United States)

Lu, Yi [Champaign, IL; Liu, Juewen [Urbana, IL

2009-02-03

A sensor system for detecting an effector or cofactor comprises (a) a nucleic acid enzyme; (b) a substrate for the nucleic acid enzyme, comprising a first polynucleotide; (c) a first set of particles comprising a second polynucleotide at least partially complementary to the substrate, where the polynucleotide is attached to the particles at its 3' terminus; and (d) a second set of particles comprising a third polynucleotide at least partially complementary to the substrate, where the polynucleotide is attached to the particles at its 5' terminus.

Sutureless intrascleral intraocular lens fixation with lamellar dissection of scleral tunnel

Directory of Open Access Journals (Sweden)

Kawaji T

2016-01-01

Full Text Available Takahiro Kawaji,1,2 Tomoki Sato,2 Hidenobu Tanihara11Department of Ophthalmology, Faculty of Life Sciences, Kumamoto University, Chuo-ku, 2Sato Eye & Internal Medicine Clinic, Kumamoto, JapanPurpose: To report the results of sutureless scleral fixation of a posterior chamber intraocular lens (IOL by using our developed simple technique.Methods: We retrospectively reviewed the medical records of 48 eyes of 47 patients who underwent sutureless intrascleral IOL fixation by using our modified technique. A 25-gauge microvitreoretinal knife was used to perform sclerotomies and create limbus-parallel scleral tunnels with lamellar dissection in which the haptics were fixed.Results: The IOLs were fixed and centered well. The mean follow-up period was 26.7 months. Postoperative complications included smooth vitreous hemorrhage in four eyes (8.3%, cystoid macular edema in two eyes (4.2%, and iris capture of the IOL in two eyes (4.2%. No other complications, such as breakage of the IOL, spontaneous IOL dislocation, or retinal detachment, were detected during the follow-up period.Conclusion: The lamellar dissection of the limbus-parallel scleral tunnel can simplify the forceps-assisted introduction of the haptics into the scleral tunnel, and this technique seemed to be safe.Keywords: intraocular lenses, ophthalmologic surgical procedures, intrascleral fixation, sutureless fixation

Thermodynamic and structural study of two-dimensional melting within monolayers or rare gases or methane physically adsorbed upon the surface of layer-like solids

International Nuclear Information System (INIS)

Tessier, Christine

1983-01-01

The 2D (two-dimensional) melting of monolayers of rare gases or methane physically adsorbed on the basal face of lamellar solids (graphite, boron nitride and lamellar halides) has been studied. Two different experimental measurements have been made: i) adsorption isotherms; ii) neutron diffraction spectra. The main part of this report deals with the 2D liquid-incommensurate solid transition within monolayers of rare gases or methane adsorbed on the basal face of lamellar halides. This transition is first order. It is observed only if certain conditions of dimensional incompatibility between the substrate and the absorbate are fulfilled. It is little affected by the structure of the underlying substrate. A number of thermodynamic parameters associated with it, are constants once properly scaled. These constants agree well with theoretical estimates for 6-12 Lennard Jones particles adsorbed on a smooth surface. For the monolayer of Xe adsorbed on graphite the temperature of the tricritical point above which melting becomes a continuous transition has been measured. The isotope effect associated with 2D melting has been investigated by comparing the behaviour of monolayers of CH 4 and CD 4 adsorbed on boron nitride. The vapor pressure of Xe has been determined in the temperature range 101-120 K. (author) [fr

Ru complexes of Hoveyda–Grubbs type immobilized on lamellar zeolites: activity in olefin metathesis reactions

Czech Academy of Sciences Publication Activity Database

Balcar, Hynek; Žilková, Naděžda; Kubů, Martin; Mazur, Michal; Bastl, Zdeněk; Čejka, Jiří

2015-01-01

Roč. 11, NOV 2015 (2015), s. 2087-2096 ISSN 1860-5397 Institutional support: RVO:61388955 Keywords : Hoveyda-Grubbs type catalyst * hybrid catalysts * lamellar zeolites Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 2.697, year: 2015

The Evolution of Splint Armour in Georgia and Byzantium: Lamellar and Scale Armour in the 10th-12th Centuries

OpenAIRE

TSURTSUMIA, Mamuka

2011-01-01

Byzantine technology was part of the military technology that existed in vast areas of Eurasia; hence study of the armament of its neighbours is important.The purpose of the present paper is to add new data about Byzantium’s Caucasian neighbour (namely, Georgia). Besides that, it also includes certain views about the stages of the evolution and provenance of splint (scale and lamellar) armour. This paper also attempts to clarify the difference between banded and linear suits of lamellar armou...

Extended constitutive laws for lamellar phases

Directory of Open Access Journals (Sweden)

Chi-Deuk Yoo

2013-10-01

Full Text Available Classically, stress and strain rate in linear viscoelastic materials are related by a constitutive relationship involving the viscoelastic modulus G(t. The same constitutive law, within Linear Response Theory, relates currents of conserved quantities and gradients of existing conjugate variables, and it involves the autocorrelation functions of the currents in equilibrium. We explore the consequences of the latter relationship in the case of a mesoscale model of a block copolymer, and derive the resulting relationship between viscous friction and order parameter diffusion that would result in a lamellar phase. We also explicitly consider in our derivation the fact that the dissipative part of the stress tensor must be consistent with the uniaxial symmetry of the phase. We then obtain a relationship between the stress and order parameter autocorrelation functions that can be interpreted as an extended constitutive law, one that offers a way to determine them from microscopic experiment or numerical simulation.

Preparation and electrochemical properties of lamellar MnO{sub 2} for supercapacitors

Energy Technology Data Exchange (ETDEWEB)

Yan, Jun; Wei, Tong [Key Laboratory of Superlight Materials and Surface Technology, Ministry of Education, College of Material Science and Chemical Engineering, Harbin Engineering University, Harbin 150001 (China); Cheng, Jie [Research Institute of Chemical Defense, Beijing 100083 (China); Fan, Zhuangjun, E-mail: fanzhj666@163.com [Key Laboratory of Superlight Materials and Surface Technology, Ministry of Education, College of Material Science and Chemical Engineering, Harbin Engineering University, Harbin 150001 (China); Zhang, Milin [Key Laboratory of Superlight Materials and Surface Technology, Ministry of Education, College of Material Science and Chemical Engineering, Harbin Engineering University, Harbin 150001 (China)

2010-02-15

Lamellar birnessite-type MnO{sub 2} materials were prepared by changing the pH of the initial reaction system via hydrothermal synthesis. The interlayer spacing of MnO{sub 2} with a layered structure increased gradually when the initial pH value varied from 12.43 to 2.81, while the MnO{sub 2}, composed of {alpha}-MnO{sub 2} and {gamma}-MnO{sub 2}, had a rod-like structure at pH 0.63. Electrochemical studies indicated that the specific capacitance of birnessite-type MnO{sub 2} was much higher than that of rod-like MnO{sub 2} at high discharge current densities due to the lamellar structure with fast intercalation/deintercalation of protons and high utilization of MnO{sub 2}. The initial specific capacitance of MnO{sub 2} prepared at pH 2.81 was 242.1 F g{sup -1} at 2 mA cm{sup -2} in 2 mol L{sup -1} (NH{sub 4}){sub 2}SO{sub 4} aqueous electrolyte. The capacitance increased by about 8.1% of initial capacitance after 200 cycles at a current density of 100 mA cm{sup -2}.

Early surfactant guided by lamellar body counts on gastric aspirate in very preterm infants

DEFF Research Database (Denmark)

Verder, Henrik Axel; Ebbesen, Finn Oluf; Fenger-Grøn, Jesper

2013-01-01

We have developed a rapid method, based on lamellar body counts (LBC) on gastric aspirate, for identifying newborns who will develop respiratory distress syndrome with a need for surfactant supplementation. Objective: We set out to test whether it was possible to improve the outcome when used in ...

Near-field enhanced femtosecond laser nano-drilling of glass substrate

International Nuclear Information System (INIS)

Zhou, Y.; Hong, M.H.; Fuh, J.Y.H.; Lu, L.; Lukyanchuk, B.S.; Wang, Z.B.

2008-01-01

Particle mask assisted near-field enhanced femtosecond laser nano-drilling of transparent glass substrate was demonstrated in this paper. A particle mask was fabricated by self-assembly of spherical 1 μm silica particles on the substrate surface. Then the samples were exposed to femtosecond laser (800 nm, 100 fs) and characterized by field emission scanning electron microscope (FESEM) and atomic force microscope (AFM). The nano-hole array was found on the glass surface. The hole sizes were measured from 200 to 300 nm with an average depth of 150 nm and increased with laser fluence. Non-linear triple-photon absorption and near-field enhancement were the main mechanisms of the nano-feature formation. Calculations based on Mie theory shows an agreement with experiment results. More debris, however, was found at high laser fluence. This can be attributed to the explosion of silica particles because the focusing point is inside the 1 μm particle. The simulation predicts that the focusing point will move outside the particle if the particle size increases. The experiment performed under 6.84 μm silica particles verified that no debris was formed. And for all the samples, no cracks were found on the substrate surface because of ultra-short pulse width of femtosecond laser. This method has potential applications in nano-patterning of transparent glass substrate for nano-structure device fabrication

Blood Compatibility of ZrO2 Particle Reinforced PEEK Coatings on Ti6Al4V Substrates

Directory of Open Access Journals (Sweden)

Jian Song

2017-11-01

Full Text Available Titanium (Ti and its alloys are widely used in biomedical devices. As biomaterials, the blood compatibility of Ti and its alloys is important and needs to be further improved to provide better functionality. In this work, we studied the suitability of zirconia (ZrO2 particle reinforced poly-ether-ether-ketone (PEEK coatings on Ti6Al4V substrates for blood-contacting implants. The wettability, surface roughness and elastic modulus of the coatings were examined. Blood compatibility tests were conducted by erythrocytes observation, hemolysis assay and clotting time of recalcified human plasma, to find out correlations between the microstructure of the ZrO2-filled PEEK composite coatings and their blood compatibilities. The results suggested that adding ZrO2 nanoparticles increased the surface roughness and improved the wettability and Derjaguin-Muller-Toporov (DMT elastic modulus of PEEK coating. The PEEK composite matrix coated Ti6Al4V specimens did not cause any aggregation of erythrocytes, showing morphological normal shapes. The hemolysis rate (HR values of the tested specimens were much less than 5% according to ISO 10993-4 standard. The values of plasma recalcification time (PRT of the tested specimens varied with the increasing amount of ZrO2 nanoparticles. Based on the results obtained, 10 wt % ZrO2 particle reinforced PEEK coating has demonstrated an optimum blood compatibility, and can be considered as a candidate to improve the performance of existing PEEK based coatings on titanium substrates.

Estimation of the Human Extrathoracic Deposition Fraction of Inhaled Particles Using a Polyurethane Foam Collection Substrate in an IOM Sampler

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Darrah K. Sleeth

2016-03-01

Full Text Available Extrathoracic deposition of inhaled particles (i.e., in the head and throat is an important exposure route for many hazardous materials. Current best practices for exposure assessment of aerosols in the workplace involve particle size selective sampling methods based on particle penetration into the human respiratory tract (i.e., inhalable or respirable sampling. However, the International Organization for Standardization (ISO has recently adopted particle deposition sampling conventions (ISO 13138, including conventions for extrathoracic (ET deposition into the anterior nasal passage (ET1 and the posterior nasal and oral passages (ET2. For this study, polyurethane foam was used as a collection substrate inside an inhalable aerosol sampler to provide an estimate of extrathoracic particle deposition. Aerosols of fused aluminum oxide (five sizes, 4.9 µm–44.3 µm were used as a test dust in a low speed (0.2 m/s wind tunnel. Samplers were placed on a rotating mannequin inside the wind tunnel to simulate orientation-averaged personal sampling. Collection efficiency data for the foam insert matched well to the extrathoracic deposition convention for the particle sizes tested. The concept of using a foam insert to match a particle deposition sampling convention was explored in this study and shows promise for future use as a sampling device.

Estimation of the Human Extrathoracic Deposition Fraction of Inhaled Particles Using a Polyurethane Foam Collection Substrate in an IOM Sampler.

Science.gov (United States)

Sleeth, Darrah K; Balthaser, Susan A; Collingwood, Scott; Larson, Rodney R

2016-03-07

Extrathoracic deposition of inhaled particles (i.e., in the head and throat) is an important exposure route for many hazardous materials. Current best practices for exposure assessment of aerosols in the workplace involve particle size selective sampling methods based on particle penetration into the human respiratory tract (i.e., inhalable or respirable sampling). However, the International Organization for Standardization (ISO) has recently adopted particle deposition sampling conventions (ISO 13138), including conventions for extrathoracic (ET) deposition into the anterior nasal passage (ET₁) and the posterior nasal and oral passages (ET₂). For this study, polyurethane foam was used as a collection substrate inside an inhalable aerosol sampler to provide an estimate of extrathoracic particle deposition. Aerosols of fused aluminum oxide (five sizes, 4.9 µm-44.3 µm) were used as a test dust in a low speed (0.2 m/s) wind tunnel. Samplers were placed on a rotating mannequin inside the wind tunnel to simulate orientation-averaged personal sampling. Collection efficiency data for the foam insert matched well to the extrathoracic deposition convention for the particle sizes tested. The concept of using a foam insert to match a particle deposition sampling convention was explored in this study and shows promise for future use as a sampling device.

Methods of etching a substrate

International Nuclear Information System (INIS)

Cosmo, J.J.; Gambino, R.J.; Harper, J.M.E.

1979-01-01

The invention relates to a method of etching a substrate. The substrate is located opposite a target electrode in a vacuum chamber, and the surface of the target electrode is bombarded with energetic particles of atomic dimensions. The target electrode is an intermetallic composition (compound, alloy or finely divided homogeneous mixture) of two metals A and B such that upon bombardment the electrode emits negative ions of metal B which have sufficient energy to produce etching of the substrate. Many target materials are exemplified. Typically the metal A has an electronegativity XA and metal B has an electronegativity XB such that Xb - Xa is greater than about 2.55 electron volts, with the exception of combinations of metals having a fractional ionicity Q less than about 0.314. The source of the energetic particles may be an ionised gas in the vacuum chamber. The apparatus and its mode of operation are described in detail. (U.K.)

Methods of etching a substrate

Energy Technology Data Exchange (ETDEWEB)

Cosmo, J J; Gambino, R J; Harper, J M.E.

1979-05-16

The invention relates to a method of etching a substrate. The substrate is located opposite a target electrode in a vacuum chamber, and the surface of the target electrode is bombarded with energetic particles of atomic dimensions. The target electrode is an intermetallic composition (compound, alloy or finely divided homogeneous mixture) of two metals A and B such that upon bombardment the electrode emits negative ions of metal B which have sufficient energy to produce etching of the substrate. Many target materials are exemplified. Typically the metal A has an electronegativity XA and metal B has an electronegativity XB such that Xb - Xa is greater than about 2.55 electron volts, with the exception of combinations of metals having a fractional ionicity Q less than about 0.314. The source of the energetic particles may be an ionised gas in the vacuum chamber. The apparatus and its mode of operation are described in detail.

Novel spatula and dissector for safer deep anterior lamellar keratoplasty

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Gustavo ,2,3 Bonfadini

2014-10-01

Full Text Available Objective: We describe a novel spatula and dissector to facilitate the big-bubble technique in deep anterior lamellar keratoplasty (DALK. Methods: A 29-year-old man who was diagnosed with bilateral keratoconus underwent deep anterior lamellar keratoplasty (DALK. After 350μm partial thickness incision of the recipient cornea, the Bonfadini dissector was inserted at the deepest point in the peripheral incision and could be advanced to the center of the cornea safely because of its "semi-sharp" tip. After achieving the big-bubble (BB separation of Descemet membrane (DM from the overlying stroma, the anterior stromal disc was removed. Viscoelastic material was placed on the stromal bed to prevent uncontrolled collapse and perforation of DM during the paracentesis blade incision into the BB. We could detect the safe opening of the BB using the Bonfadini dissector by the leakage of air bubbles into the viscoelastic material. After injecting viscoelastic material into the BB space, we inserted the Bonfadini spatula into the bigbubble safely because of its curved profile and blunt edges. The groove along the length of the Bonfadini spatula enables safe and efficient incision or the residual stromal tissue using the pointed end of a sharp blade while protecting the underlying DM. After removal of posterior stroma, the donor button was sutured with 16 interrupted 10-0 nylon sutures. Results: This technique and the use of the Bonfadini spatula and dissector facilitate exposure of Descemet membrane. Conclusion: The smooth Bonfadini DALK spatula and dissector facilitate safe and efficient completion of DALK surgery.

Repair of articular osteochondral defects of the knee joint using a composite lamellar scaffold.

Science.gov (United States)

Lv, Y M; Yu, Q S

2015-04-01

The major problem with repair of an articular cartilage injury is the extensive difference in the structure and function of regenerated, compared with normal cartilage. Our work investigates the feasibility of repairing articular osteochondral defects in the canine knee joint using a composite lamellar scaffold of nano-ß-tricalcium phosphate (ß-TCP)/collagen (col) I and II with bone marrow stromal stem cells (BMSCs) and assesses its biological compatibility. The bone-cartilage scaffold was prepared as a laminated composite, using hydroxyapatite nanoparticles (nano-HAP)/collagen I/copolymer of polylactic acid-hydroxyacetic acid as the bony scaffold, and sodium hyaluronate/poly(lactic-co-glycolic acid) as the cartilaginous scaffold. Ten-to 12-month-old hybrid canines were randomly divided into an experimental group and a control group. BMSCs were obtained from the iliac crest of each animal, and only those of the third generation were used in experiments. An articular osteochondral defect was created in the right knee of dogs in both groups. Those in the experimental group were treated by implanting the composites consisting of the lamellar scaffold of ß-TCP/col I/col II/BMSCs. Those in the control group were left untreated. After 12 weeks of implantation, defects in the experimental group were filled with white semi-translucent tissue, protruding slightly over the peripheral cartilage surface. After 24 weeks, the defect space in the experimental group was filled with new cartilage tissues, finely integrated into surrounding normal cartilage. The lamellar scaffold of ß-TCP/col I/col II was gradually degraded and absorbed, while new cartilage tissue formed. In the control group, the defects were not repaired. This method can be used as a suitable scaffold material for the tissue-engineered repair of articular cartilage defects. Cite this article: Bone Joint Res 2015;4:56-64. ©2015 The British Editorial Society of Bone & Joint Surgery.

Kinetics and mechanism of the pressure-induced lamellar order/disorder transition in phosphatidylethanolamine: a time-resolved X-ray diffraction study.

Science.gov (United States)

Mencke, A P; Caffrey, M

1991-03-05

By using synchrotron radiation, a movie was made of the X-ray scattering pattern from a biological liquid crystal undergoing a phase transition induced by a pressure jump. The system studied includes the fully hydrated phospholipid dihexadecylphosphatidylethanolamine in the lamellar gel (L beta') phase at a temperature of 68 degrees C and a pressure of 9.7 MPa (1400 psig). Following the rapid release of pressure to atmospheric the L beta' phase transforms slowly into the lamellar liquid crystal (L alpha) phase. The pressure perturbation is applied with the intention of producing a sudden phase disequilibrium followed by monitoring the system as it relaxes to its new equilibrium condition. Remarkably, the proportion of sample in the L alpha phase grows linearly with time, taking 37 s to totally consume the L beta' phase. The time dependencies of radius, peak intensity, and width of the powder diffraction ring of the low-angle (001) lamellar reflections were obtained from the movie by image processing. The concept of an "effective pressure" is introduced to account for the temperature variations that accompany the phase transition and to establish that the observed large transit time is indeed intrinsic to the sample and not due to heat exchange with the environment. The reverse transformation, L alpha to L beta', induced by a sudden jump from atmospheric pressure to 9.7 MPa, is complete in less than 13 s. These measurements represent a new approach for studying the kinetics of lipid phase transitions and for gaining insights into the mechanism of the lamellar order/disorder transition.

Hierarchical Formation of Fibrillar and Lamellar Self-Assemblies from Guanosine-Based Motifs

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Paolo Neviani

2010-01-01

Full Text Available Here we investigate the supramolecular polymerizations of two lipophilic guanosine derivatives in chloroform by light scattering technique and TEM experiments. The obtained data reveal the presence of several levels of organization due to the hierarchical self-assembly of the guanosine units in ribbons that in turn aggregate in fibrillar or lamellar soft structures. The elucidation of these structures furnishes an explanation to the physical behaviour of guanosine units which display organogelator properties.

Morphological Evolution of Block Copolymer Particles: Effect of Solvent Evaporation Rate on Particle Shape and Morphology.

Science.gov (United States)

Shin, Jae Man; Kim, YongJoo; Yun, Hongseok; Yi, Gi-Ra; Kim, Bumjoon J

2017-02-28

Shape and morphology of polymeric particles are of great importance in controlling their optical properties or self-assembly into unusual superstructures. Confinement of block copolymers (BCPs) in evaporative emulsions affords particles with diverse structures, including prolate ellipsoids, onion-like spheres, oblate ellipsoids, and others. Herein, we report that the evaporation rate of solvent from emulsions encapsulating symmetric polystyrene-b-polybutadiene (PS-b-PB) determines the shape and internal nanostructure of micron-sized BCP particles. A distinct morphological transition from the ellipsoids with striped lamellae to the onion-like spheres was observed with decreasing evaporation rate. Experiments and dissipative particle dynamics (DPD) simulations showed that the evaporation rate affected the organization of BCPs at the particle surface, which determined the final shape and internal nanostructure of the particles. Differences in the solvent diffusion rates in PS and PB at rapid evaporation rates induced alignment of both domains perpendicular to the particle surface, resulting in ellipsoids with axial lamellar stripes. Slower evaporation rates provided sufficient time for BCP organization into onion-like structures with PB as the outermost layer, owing to the preferential interaction of PB with the surroundings. BCP molecular weight was found to influence the critical evaporation rate corresponding to the morphological transition from ellipsoid to onion-like particles, as well as the ellipsoid aspect ratio. DPD simulations produced morphologies similar to those obtained from experiments and thus elucidated the mechanism and driving forces responsible for the evaporation-induced assembly of BCPs into particles with well-defined shapes and morphologies.

Functionalization of lamellar molybdenum disulphide nanocomposite with gold nanoparticles

International Nuclear Information System (INIS)

Lavayen, V.; O'Dwyer, C.; Ana, M.A. Santa; Mirabal, N.; Benavente, E.; Cardenas, G.; Gonzalez, G.; Torres, C.M. Sotomayor

2007-01-01

This work explores the functionalization of an organic-inorganic MoS 2 lamellar compound, prepared by a chemical liquid deposition method (CLD), that has an interlamellar distance of ∼5.2 nm, using clusters of gold nanoparticles. The gold nanoparticles have a mean diameter of 1.2 nm, a stability of ∼85 days, and a zeta potential measured to be ζ -6.8 mV (solid). The nanoparticles are localized in the hydrophilic zones, defined by the presence of amine groups of the surfactant between the lamella of MoS 2 . SEM, TEM, EDAX and electron diffraction provide conclusive evidence of the interlamellar insertion of the gold nanoparticles in the MoS 2

Functionalization of lamellar molybdenum disulphide nanocomposite with gold nanoparticles

Energy Technology Data Exchange (ETDEWEB)

Lavayen, V. [Tyndall National Institute, University College Cork, Lee Maltings, Prospect Row, Cork (Ireland) and Department of Chemistry, Faculty of Sciences, Universidad de Chile, P.O. Box 653, Santiago (Chile)]. E-mail: vlavayen@tyndall.ie; O' Dwyer, C. [Tyndall National Institute, University College Cork, Lee Maltings, Prospect Row, Cork (Ireland); Ana, M.A. Santa [Department of Chemistry, Faculty of Sciences, Universidad de Chile, P.O. Box 653, Santiago (Chile); Mirabal, N. [Department of Chemistry, Faculty of Sciences, Universidad de Chile, P.O. Box 653, Santiago (Chile); Benavente, E. [Department of Chemistry, Universidad Tecnologica Metropolitana, P.O. Box 9845, Santiago (Chile); Cardenas, G. [Department of Polymers, Faculty of Chemistry Science, Universidad de Concepcion, P.O. Box 160-C, Concepcion (Chile); Gonzalez, G. [Department of Chemistry, Faculty of Sciences, Universidad de Chile, P.O. Box 653, Santiago (Chile); Torres, C.M. Sotomayor [Tyndall National Institute, University College Cork, Lee Maltings, Prospect Row, Cork (Ireland)

2007-01-30

This work explores the functionalization of an organic-inorganic MoS{sub 2} lamellar compound, prepared by a chemical liquid deposition method (CLD), that has an interlamellar distance of {approx}5.2 nm, using clusters of gold nanoparticles. The gold nanoparticles have a mean diameter of 1.2 nm, a stability of {approx}85 days, and a zeta potential measured to be {zeta} -6.8 mV (solid). The nanoparticles are localized in the hydrophilic zones, defined by the presence of amine groups of the surfactant between the lamella of MoS{sub 2}. SEM, TEM, EDAX and electron diffraction provide conclusive evidence of the interlamellar insertion of the gold nanoparticles in the MoS{sub 2}.

Influence of shape and size of the particles on jigging separation of plastics mixture.

Science.gov (United States)

Pita, Fernando; Castilho, Ana

2016-02-01

Plastics are popular for numerous applications due to their high versatility and favourable properties such as endurance, lightness and cheapness. Therefore the generation of plastic waste is constantly increasing, becoming one of the larger categories in municipal solid waste. Almost all plastic materials are recyclable, but for the recycling to be possible it is necessary to separate the different types of plastics. The aim of this research was to evaluate the performance of the jig separation of bi-component plastic mixtures. For this study six granulated plastics had been used: Polystyrene (PS), Polymethyl methacrylate (PMMA), Polyethylene Terephthalate (PET-S, PET-D) and Polyvinyl Chloride (PVC-M, PVC-D). Plastics mixtures were subjected to jigging in a laboratorial Denver mineral jig. The results showed that the quality of the jigging separation varies with the mixture, the density differences and with the size and shape of the particles. In the case of particles with more regular shapes the quality of separation of bi-component plastic mixtures improved with the increase of the particle size. For lamellar particles the influence of particle size was minimal. In general, the beneficiation of plastics with similar densities was not effective, since the separation efficiency was lower than 25%. However, in bi-component plastic mixtures that join a low density plastic (PS) with a high density one (PMMA, PET-S, PET-D, PVC-M and PVC-D), the quality of the jigging separation was greatly improved. The PS grade in the sunk was less than 1% for all the plastic mixtures. Jigging proved to be an effective method for the separation of bi-component plastic mixtures. Jigging separation will be enhanced if the less dense plastic, that overflows, has a lamellar shape and if the denser plastic, that sinks, has a regular one. Copyright © 2015 Elsevier Ltd. All rights reserved.

Cold Gas-Sprayed Deposition of Metallic Coatings onto Ceramic Substrates Using Laser Surface Texturing Pre-treatment

Science.gov (United States)

Kromer, R.; Danlos, Y.; Costil, S.

2018-04-01

Cold spraying enables a variety of metals dense coatings onto metal surfaces. Supersonic gas jet accelerates particles which undergo with the substrate plastic deformation. Different bonding mechanisms can be created depending on the materials. The particle-substrate contact time, contact temperature and contact area upon impact are the parameters influencing physicochemical and mechanical bonds. The resultant bonding arose from plastic deformation of the particle and substrate and temperature increasing at the interface. The objective was to create specific topography to enable metallic particle adhesion onto ceramic substrates. Ceramic did not demonstrate deformation during the impact which minimized the intimate bonds. Laser surface texturing was hence used as prior surface treatment to create specific topography and to enable mechanical anchoring. Particle compressive states were necessary to build up coating. The coating deposition efficiency and adhesion strength were evaluated. Textured surface is required to obtain strong adhesion of metallic coatings onto ceramic substrates. Consequently, cold spray coating parameters depend on the target material and a methodology was established with particle parameters (diameters, velocities, temperatures) and particle/substrate properties to adapt the surface topography. Laser surface texturing is a promising tool to increase the cold spraying applications.

Clinical observation of corneal lamellar debridement combined with sutureless amniotic membrane transplantation for the treatment of superficial fungal keratitis

Directory of Open Access Journals (Sweden)

Huang Zhang

2014-09-01

Full Text Available AIM:To evaluate the clinical efficacy of corneal lamellar debridement combined with sutureless amniotic membrane transplantation for the treatment of superficial fungal keratitis.METHODS:Totally 22 cases(22 eyeswith superficial fungal keratitis were referred to our hospital from April 2012 to October 2013. The patients with persistent cornea ulcer after treatment of local and systemic antifungal drugs underwent corneal lamellar debridement combined with sutureless amniotic membrane transplantation, and the recipient bed was covered with an amniotic membrane using fibrin sealant during the operation. All patients were still given topical antifungal therapy for 1-2mo after operation. The followed-up time was 3mo or above. We observed the corneal healing and amniotic membrane adhesion by split lamp microscope, and investigated the transformation of amniotic membrane and fungal infection recurrence with confocal microscope. RESULTS: Corneal edema and anterior chamber reaction of 21 patients disappeared gradually, and no amniotic membrane graft dissolved and shed off within 1-2wk postoperatively. Two weeks after operation, the graft integrated into the corneal and the corneal wounds' thickness increased gradually, the corneal epithelium reconstructed and corneas became clear. Four weeks after operation, the corneal scarring developed gradually and fluorescence staining was negative. Nineteen cases' amniotic membranes that adhered with the cornea dissolved 4wk after operation. There were different degrees of corneal nebula or macula remained 3mo postoperatively. All patients' vision improved in varying degrees, except in 1 case with fungal keratitis who had been cured by lamellar keratoplasty.CONCLUSION:Corneal lamellar debridement combined with sutureless amniotic membrane transplantation can effectively remove the foci of inflammation, improve the local efficacy, shorten the operation time, relieve the postoperative reaction, and promote cornea

Fabrication of non-hexagonal close packed colloidal array on a substrate by transfer

Science.gov (United States)

Banik, Meneka; Mukherjee, Rabibrata

Self-organized colloidal arrays find application in fabrication of solar cells with advanced light management strategies. We report a simple spincoating based approach for fabricating two dimensional colloidal crystals with hexagonal and non-hexagonal close packed assembly on flat and nanopatterned substrates. The non-HCP arrays were fabricated by spin coating the particles onto soft lithographically fabricated substrates. The substrate patterns impose directionality to the particles by confining them within the grooves. We have developed a technique by which the HCP and non-HCP arrays can be transferred to any surface. For this purpose the colloidal arrays were fabricated on a UV degradable PMMA layer, resulting in transfer of the particles on UV exposure. This allows the colloidal structures to be transported across substrates irrespective of their surface energy, wettability or morphology. Since the particles are transferred without exposing it to any kind of chemical or thermal environment, it can be utilized for placing particles on top of thin film solar cells for improving their absorption efficiency.

Fabrication of microstructures and microdevices by the particle assemblage

Science.gov (United States)

Kobayashi, Mikihiko; Shinya, Norio; Dan, Takehiro; Fudouzi, Hiroshi; Konno, Takeshi; Egashira, Mitsuru

2001-08-01

We aim to fabricate microstructure and microdevices by integrating and arranging powder particles, i.e., the particle assemblage. We have developed three assembling techniques of the particles. The details of the assembling techniques and samples of the assembled microstructures are introduced. A manipulator is developed to manipulate and to weld metal particles by using a tungsten probe. Nickel alloy particles of 50 micrometers were piled on a gold substrate by the manipulator, and a leaning tower of the particles is fabricated. The array of the leaning tower is considered to act as an actuator. For the integration of a great number of particles, we developed another method based on the principle with the xerography. An electron beam or an ion beam is irradiated on an insulating substrate. An electrified pattern is formed on the substrate by the doped electron or doped ion. Fine particles are attracted to the pattern by the electrostatic force. Thus, we can arrange particles by immersing the substrate in the suspension of particles. The third is a productive method of ordered mixture by the electrostatic force. A self- thermostatic heater is made from the composite particles of BaTiO3 and In produced by the method.

Development of an optimal filter substrate for the identification of small microplastic particles in food by micro-Raman spectroscopy.

Science.gov (United States)

Oßmann, Barbara E; Sarau, George; Schmitt, Sebastian W; Holtmannspötter, Heinrich; Christiansen, Silke H; Dicke, Wilhelm

2017-06-01

When analysing microplastics in food, due to toxicological reasons it is important to achieve clear identification of particles down to a size of at least 1 μm. One reliable, optical analytical technique allowing this is micro-Raman spectroscopy. After isolation of particles via filtration, analysis is typically performed directly on the filter surface. In order to obtain high qualitative Raman spectra, the material of the membrane filters should not show any interference in terms of background and Raman signals during spectrum acquisition. To facilitate the usage of automatic particle detection, membrane filters should also show specific optical properties. In this work, beside eight different, commercially available membrane filters, three newly designed metal-coated polycarbonate membrane filters were tested to fulfil these requirements. We found that aluminium-coated polycarbonate membrane filters had ideal characteristics as a substrate for micro-Raman spectroscopy. Its spectrum shows no or minimal interference with particle spectra, depending on the laser wavelength. Furthermore, automatic particle detection can be applied when analysing the filter surface under dark-field illumination. With this new membrane filter, analytics free of interference of microplastics down to a size of 1 μm becomes possible. Thus, an important size class of these contaminants can now be visualized and spectrally identified. Graphical abstract A newly developed aluminium coated polycarbonate membrane filter enables automatic particle detection and generation of high qualitative Raman spectra allowing identification of small microplastics.

The lamellar period in symmetric diblock copolymer thin films studied by neutron reflectivity and AFM

DEFF Research Database (Denmark)

Gadegaard, N.; Almdal, K.; Larsen, N.B.

1999-01-01

The lamellar structure of a symmetric diblock copolymer was studied as a function of temperature. We used dPEP-PDMS with a molecular weight of 8.3 kg/mol as model system. The polymer was dissolved in chloroform and spin-casted on silicon wafers into thin uniform films. The degree and direction...

Spectral phasor analysis of LAURDAN fluorescence in live A549 lung cells to study the hydration and time evolution of intracellular lamellar body-like structures

DEFF Research Database (Denmark)

Malacrida, Leonel; Astrada, Soledad; Briva, Arturo

2016-01-01

Using LAURDAN spectral imaging and spectral phasor analysis we concurrently studied the growth and hydration state of subcellular organelles (lamellar body-like, LB-like) from live A549 lung cancer cells at different post-confluence days. Our results reveal a time dependent two-step process...... governing the size and hydration of these intracellular LB-like structures. Specifically, a first step (days 1 to 7) is characterized by an increase in their size, followed by a second one (days 7 to 14) where the organelles display a decrease in their global hydration properties. Interestingly, our results...... also show that their hydration properties significantly differ from those observed in well-characterized artificial lamellar model membranes, challenging the notion that a pure lamellar membrane organization is present in these organelles at intracellular conditions. Finally, these LB-like structures...

Soft solution synthesis and intense visible photoluminescence of lamellar zinc oxide hybrids

International Nuclear Information System (INIS)

Sağlam, Özge

2013-01-01

Graphical abstract: -- In this study, we demonstrate the synthesis of layered zinc oxide films intercalated with dodecyl sulphate ions by a simple soft solution process. The presence of potassium (K + ) and lithium (Li + ) ions in the precursor solution of layered zinc hydroxide resulted in lamellar hybrid zinc oxide films instead of layered zinc hydroxides. On the other hand, the addition of nickel phthalocyanine induces zinc hydroxide host layers which exhibit an intense blue emission. This is also promoted by K + and Li + ions

Retraction Note to: Ultra-High Strength and Ductile Lamellar-Structured Powder Metallurgy Binary Ti-Ta Alloys

Science.gov (United States)

Liu, Yong; Xu, Shenghang; Wang, Xin; Li, Kaiyang; Liu, Bin; Wu, Hong; Tang, Huiping

2018-05-01

The editors and authors have retracted the article, "Ultra-High Strength and Ductile Lamellar-Structured Powder Metallurgy Binary Ti-Ta Alloys" by Yong Liu, Shenghang Xu, Xin Wang, Kaiyang Li, Bin Liu, Hong Wu, and Huiping Tang (https://doi.org/10.1007/s11837-015-1801-1).

Porous chromatographic materials as substrates for preparing synthetic nuclear explosion debris particles

International Nuclear Information System (INIS)

Harvey, S.D.; Carman, A.J.; Martin Liezers; Antolick, K.C.; Garcia, B.J.; Eiden, G.C.; Sweet, L.E.

2013-01-01

Several porous chromatographic materials were investigated as synthetic substrates for preparing surrogate nuclear explosion debris particles. Eighteen metals, including some of forensic interest, were loaded onto materials by immersing them in metal solutions (556 mg/L of each metal) to fill the pores, applying gentle heat (110 deg C) to drive off water, and then treating them at high temperatures (up to 800 deg C) in air to form less soluble metal species. High-boiling-point metals were uniformly loaded on spherical controlled-pore glass to emulate early fallout, whereas low-boiling-point metals were loaded on core-shell silica to represent coated particles formed later in the nuclear fallout-formation process. Analytical studies characterized material balance and the formation of recalcitrant species. Metal loading was 1.5-3 times higher than expected from the pore volume alone, a result attributed to surface coating. Most metals were passively loaded; that is, solutions filled the pores without active metal discrimination. However, niobium and tin concentrations were lower in solutions after pore filling, and were found in elevated concentrations in the final products, indicating selective loading. High-temperature treatments caused reduced solubility of several metals, and the loss of some volatile species (rhenium and tellurium). Sample preparation reproducibility was high (the inter- and intra-batch relative standard deviations were 7.8 and 0.84 %, respectively) indicating suitability for use as a working standard for analytical methods development. We anticipate future standardized radionuclide-loaded materials will find use in radioanalytical methods development and/or serve as a starting material for the synthesis of more complex nuclear explosion debris forms (e.g., Trinitite). (author)

A study for the detection of ionizing particles with phototransistors on thick high-resistivity silicon substrates

International Nuclear Information System (INIS)

Batignani, G.; Angelini, C.; Bisogni, M.G.; Boscardin, M.; Bettarini, S.; Bondioli, M.; Bosisio, L.; Bucci, F.; Calderini, G.; Carpinelli, M.; Ciacchi, M.; Dalla Betta, G.F.; Dittongo, S.; Forti, F.; Giorgi, M.A.; Gregori, P.; Han, D.J.; Manfredi, P.F.; Manghisoni, M.; Marchiori, G.; Neri, N.; Novelli, M.; Paoloni, E.; Piemonte, C.; Rachevskaia, I.; Rama, M.; Ratti, L.; Re, V.; Rizzo, G.; Ronchin, S.; Rosso, V.; Simi, G.; Speziali, V.; Stefanini, A.; Zorzi, N.

2004-01-01

We report on bipolar NPN phototransistors fabricated at ITC-IRST on thick high-resistivity silicon substrates. The phototransistor emitter is composed of a phosphorus n+ implant, the base is a diffused high-energy boron implant, and the collector is the 600-800 μm thick silicon bulk, contacted on the backplane. We have studied the current amplification for two different doping profiles of the emitter, obtaining values of β ranging from 60 to 3000. For various emitter and base configurations, we measured the static device characteristics and extracted the leakage currents and the base resistance, verifying the fundamental relationship between them and the total base capacitances. The use of such phototransistors to detect ionizing particles is exploited and discussed

A study for the detection of ionizing particles with phototransistors on thick high-resistivity silicon substrates

Energy Technology Data Exchange (ETDEWEB)

Batignani, G. E-mail: giovanni.batignani@pi.infn.it; Angelini, C.; Bisogni, M.G.; Boscardin, M.; Bettarini, S.; Bondioli, M.; Bosisio, L.; Bucci, F.; Calderini, G.; Carpinelli, M.; Ciacchi, M.; Dalla Betta, G.F.; Dittongo, S.; Forti, F.; Giorgi, M.A.; Gregori, P.; Han, D.J.; Manfredi, P.F.; Manghisoni, M.; Marchiori, G.; Neri, N.; Novelli, M.; Paoloni, E.; Piemonte, C.; Rachevskaia, I.; Rama, M.; Ratti, L.; Re, V.; Rizzo, G.; Ronchin, S.; Rosso, V.; Simi, G.; Speziali, V.; Stefanini, A.; Zorzi, N

2004-09-01

We report on bipolar NPN phototransistors fabricated at ITC-IRST on thick high-resistivity silicon substrates. The phototransistor emitter is composed of a phosphorus n+ implant, the base is a diffused high-energy boron implant, and the collector is the 600-800 {mu}m thick silicon bulk, contacted on the backplane. We have studied the current amplification for two different doping profiles of the emitter, obtaining values of {beta} ranging from 60 to 3000. For various emitter and base configurations, we measured the static device characteristics and extracted the leakage currents and the base resistance, verifying the fundamental relationship between them and the total base capacitances. The use of such phototransistors to detect ionizing particles is exploited and discussed.

Simultaneous topography-guided PRK followed by corneal collagen cross-linking after lamellar keratoplasty for keratoconus

Directory of Open Access Journals (Sweden)

Spadea L

2012-11-01

Full Text Available Leopoldo Spadea,1 Marino Paroli21University of L’Aquila, Department of Biotechnological and Applied Clinical Sciences, Eye Clinic, L’Aquila, 2La Sapienza University, Department of Biotechnology and Medical-Surgical Sciences, Latina, ItalyBackground: The purpose of this paper is to report the results of using combined treatment of customized excimer laser-assisted photorefractive keratectomy (PRK and prophylactic corneal collagen crosslinking (CXL for residual refractive error in a group of patients who had previously undergone lamellar keratoplasty for keratoconus.Methods: The study included 14 eyes from 14 patients who had originally been treated for keratoconus in one eye by excimer laser-assisted lamellar keratoplasty (ELLK, and subsequently presented with residual ametropia (-6.11 D ± 2.48, range -2.50 to -9.50. After a mean 40.1 ± 12.4 months since ELLK they underwent combined simultaneous corneal regularization treatment with topographically guided transepithelial excimer laser PRK (central corneal regularization and corneal CXL induced by riboflavin-ultraviolet A.Results: After a mean 15 ± 6.5 (range 6–24 months, all eyes gained at least one Snellen line of uncorrected distance visual acuity (range 1–10. No patient lost lines of corrected distance visual acuity, and four patients gained three lines of corrected distance visual acuity. Mean manifest refractive spherical equivalent was -0.79 ± 2.09 (range +1 to -3.0 D, and topographic keratometric astigmatism was 5.02 ± 2.93 (range 0.8–8.9 D. All the corneas remained clear (haze < 1.Conclusion: The combination of customized PRK and corneal CXL provided safe and effective results in the management of corneal regularization for refractive purposes after ELLK for keratoconus.Keywords: corneal collagen crosslinking, excimer laser-assisted lamellar keratoplasty, photorefractive keratectomy

Stochastic Computer Simulation of Cermet Coatings Formation

Directory of Open Access Journals (Sweden)

Oleg P. Solonenko

2015-01-01

Full Text Available An approach to the modeling of the process of the formation of thermal coatings lamellar structure, including plasma coatings, at the spraying of cermet powders is proposed. The approach based on the theoretical fundamentals developed which could be used for rapid and sufficiently accurate prediction of thickness and diameter of cermet splats as well as temperature at interface “flattening quasi-liquid cermet particle-substrate” depending on the key physical parameters (KPPs: temperature, velocity and size of particle, substrate temperature, and concentration of finely dispersed solid inclusions uniformly distributed in liquid metal binder. The results are presented, which concern the development of the computational algorithm and the program complex for modeling the process of laying the splats in the coating with regard to the topology of its surface, which varies dynamically at the spraying, as well as the formation of lamellar structure and porosity of the coating. The results of numerical experiments are presented through the example of thermal spraying the cermet TiC-30 vol.% NiCr powder, illustrating the performance of the developed computational technology.

Femtosecond laser-assisted deep anterior lamellar keratoplasty in phototherapeutic keratectomy versus the big-bubble technique in keratoconus

Directory of Open Access Journals (Sweden)

Jarbas Pereira de Macedo

2018-05-01

Full Text Available AIM: To compare the functional and anatomic results of femtosecond laser (FSL-assisted deep anterior lamellar keratoplasty (DALK associated with phototherapeutic keratectomy (PTK and FSL-assisted DALK performed using the big-bubble technique in keratoconus. METHODS: During the first phase of the study, an electron microscopy histopathology pilot study was conducted that included four unsuitable donor corneas divided into two groups: in FSL group, FSL lamellar cuts were performed on two corneas and in FSL+PTK group, PTK was performed at the stromal beds of two corneas after FSL lamellar cuts were made. During the second phase of the study, a randomized clinical trial was conducted that included two treatment groups of patients with keratoconus: group 1 (n=14 eyes underwent FSL-assisted DALK associated with PTK and group 2 (n=12 eyes underwent FSL-assisted DALK associated with the big-bubble technique. The main outcome measures were the postoperative visual acuity (VA and optical coherence tomography (OCT measurements, confocal microscopic findings, and contrast sensitivity. RESULTS: In the pilot study, histopathology showed a more regular stromal bed in the FSL+PTK group. In the clinical trial, group 1 had significantly worse best spectacle-corrected VA and contrast sensitivity (P<0.05 for both comparisons. The residual stromal bed measured by OCT was significantly (P<0.05 thicker in group 1. Confocal microscopy detected opacities only at the donor-receptor interface in group 1. CONCLUSION: Patients with keratoconus treated with FSL-assisted DALK performed using the big-bubble technique fare better than treated with FSL-assisted DALK associated with PTK.

Effect of microstructure evolution of the lamellar alpha on impact toughness in a two-phase titanium alloy

International Nuclear Information System (INIS)

Xu, Jianwei; Zeng, Weidong; Zhao, Yawei; Jia, Zhiqiang

2016-01-01

The effects of the evolution of the lamellar alpha microstructure on the impact toughness of Ti-17 alloy are investigated. For this purpose, the beta-processed material is isothermally forged at 820 °C and subsequently heat treated using the combination of solid solution and aging treatment. Then the impact tests are carried out at room temperature. The corresponding microstructure and fracture surface are examined by scanning electron microscope (SEM). Microstructural observations reveal that globularization behavior is the main feature of microstructure evolution and the globularization fraction increases with the increasing of prestrain. However, globularization behavior has a negative influence on the impact toughness of Ti-17 alloy. In this work, the impact toughness have been obtained in the range of 29–55 J/cm 2 via varying globularization fraction of alpha phase. A linear relationship between the impact toughness and globularization fraction can be observed though the quantitative analysis. The linear equation is expressed as A=−0.3232f+59.885. The two major reasons can be used to explain the effect of globularization fraction on the impact property of Ti-17 alloy. One explanation is that the lamellar structure can provide excellent interfacial strengthening effect, which can improve the toughness of material, and makes it not easy to fracture. On the other hand, the fracture surface of specimen with the lamellar structure has larger amplitude of ups and downs. A long crack path length will be generated during fracture process. By contrast, the fracture of specimen with the equiaxed structure presents more flat surface and shorter crack path.

Experimental and Numerical Study of the Influence of Substrate Surface Preparation on Adhesion Mechanisms of Aluminum Cold Spray Coatings on 300M Steel Substrates

Science.gov (United States)

Nastic, A.; Vijay, M.; Tieu, A.; Rahmati, S.; Jodoin, B.

2017-10-01

The effect of substrate surface topography on the creation of metallurgical bonds and mechanical anchoring points has been studied for the cold spray deposition of pure aluminum on 300M steel substrate material. The coatings adhesion strength showed a significant decrease from 31.0 ± 5.7 MPa on polished substrates to 6.9 ± 2.0 MPa for substrates with roughness of 2.2 ± 0.5 μm. Strengths in the vicinity of 45 MPa were reached for coatings deposited onto forced pulsed waterjet treated surfaces with roughnesses larger than 33.8 μm. Finite element analysis has confirmed the sole presence of mechanical anchoring in coating adhesion strength for all surface treatment except polished surfaces. Grit embedment has been shown to be non-detrimental to coating adhesion for the current deposited material combination. The particle deformation process during impacts has been studied through finite element analysis using the Preston-Tonks-Wallace (PTW) constitutive model. The obtained equivalent plastic strain (PEEQ), temperature, contact pressure and velocity vector were correlated to the particle ability to form metallurgical bonds. Favorable conditions for metallurgical bonding were found to be highest for particles deposited on polished substrates, as confirmed by fracture surface analysis.

Numerical study of the spreading and solidification of a molten particle impacting onto a rigid substrate under plasma spraying conditions

Directory of Open Access Journals (Sweden)

Oukach Soufiane

2015-01-01

Full Text Available This paper deals with simulation of the spreading and solidification of a fully molten particle impacting onto a preheated substrate under traditional plasma spraying conditions. The multiphase problem governing equations of mass, momentum and energy conservation taking into account heat transfer by conduction, convection and phase change are solved by using a Finite Element approach. The interface between molten particle and surrounding air, is tracked using the Level Set method. The effect of the Reynolds number on the droplet spreading and solidification, using a wide range of impact velocities (40-250m/s, is reported. A new correlation that predicts the final spread factor of splat as a function of Reynolds number is obtained. Thermal contact resistance, viscous dissipation, wettability and surface tension forces effects are taken into account.

Preparation and characterization of nanostructured ZrO2 coatings on dense and porous substrates

International Nuclear Information System (INIS)

Shi Jingyu; Verweij, Henk

2008-01-01

Nanostructured ZrO 2 coatings are prepared on both dense and porous substrates by wet-chemical deposition of non-agglomerated 5 nm precursor particle dispersions, followed by thermal processing. The precursor particle dispersions are made by modified emulsion precipitation and a purification treatment to remove reaction products and additives. The coatings are formed by depositing the precursor nanoparticle dispersion directly onto the substrate, followed by drying and heating at 600 deg. C. Scanning electron microscopy and cross-sectional transmission electron microscopy observations of the heat-treated coatings indicate that the ZrO 2 coating on dense Si wafer substrate has a homogeneous, dense particle packing structure with shallow meniscus-shaped depressions in the surface, and microcracks below the meniscus surface. On the other hand, coatings formed on a meso-porous γ-alumina membrane substrate are free of defects, but with a lower packing density. The mechanism of the substrate effect on the particle packing behavior and defect formation during coating deposition is discussed. It is expected that by using a thin porous substrate with reduced capillary force, a defect-free, homogenously dense-packed coating structure can be achieved

Method to detect biological particles

International Nuclear Information System (INIS)

Giaever, I.

1976-01-01

A medical-diagnostic method to detect immunological as well as other specific reactions is described. According to the invention, first reactive particles (e.g. antibodies) are adsorbed on the surface of a solid, non-reactive substrate. The coated substrate is subjected to a solution which one assumes to contain the second biological particles (e.g. antigens) which are specific to the first and form complexes with these. A preferential radioactive labelling (e.g. with iodine 125) of the second biological particle is then directly or indirectly carried out. Clearage follows labelling in order to separate the second biological particles from the first ones. A specific splitting agent can selectively break the bond of both types of particle. The splitting agent solution is finally separated off and its content is investigated for the presence of labelling. (VJ) [de

Butterfly patterns in a sheared lamellar-system

Energy Technology Data Exchange (ETDEWEB)

Lindner, P [Institut Max von Laue - Paul Langevin (ILL), 38 - Grenoble (France); Zipfel, J; Richtering, W [Freiburg Univ. (Germany)

1997-04-01

A technologically important extension of `classical` scattering techniques is to investigate soft-matter systems under non-equilibrium conditions. Shear flow is known to have a profound influence on the structure and orientation of complex fluids like thermotropic or lyotropic liquid-crystals, colloidal and polymeric solutions. There is a fundamental interest in understanding the microscopic structure and dynamics of such complex fluids as the macroscopic material properties might change with the application of an external perturbation like shear. The following example illustrates a recent study of the influence of shear on the structure of a lyotropic lamellar phase. Results using a cone-and-plate and the ILL Couette type shear-cell were obtained by rheo-small-angle light scattering (rheo-SALS) and small-angle neutron scattering (SANS) at D11. Because of the broad range of momentum transfer Q available at D11 a characteristic butterfly-pattern with a scattering peak revealing both the structure and the supramolecular structure of the system could be detected at very low Q. (author). 5 refs.

Particle adhesion and removal

CERN Document Server

Mittal, K L

2015-01-01

The book provides a comprehensive and easily accessible reference source covering all important aspects of particle adhesion and removal.  The core objective is to cover both fundamental and applied aspects of particle adhesion and removal with emphasis on recent developments.  Among the topics to be covered include: 1. Fundamentals of surface forces in particle adhesion and removal.2. Mechanisms of particle adhesion and removal.3. Experimental methods (e.g. AFM, SFA,SFM,IFM, etc.) to understand  particle-particle and particle-substrate interactions.4. Mechanics of adhesion of micro- and  n

Ribbon phase in a phase-separated lyotropic lamellar-sponge mixture under shear flow

Science.gov (United States)

Cristobal, G.; Rouch, J.; Panizza, P.; Narayanan, T.

2001-07-01

We report the effect of shear flow on a phase-separated system composed of lyotropic lamellar (Lα) and sponge (L3) phases in a mixture of brine, surfactant, and cosurfactant. Optical microscopy, small-angle light, and x-ray scattering measurements are consistent with the existence of a steady state made of multilamellar ribbonlike structures aligned in the flow direction. At high shear rates, these ribbonlike structures become unstable and break up into monodisperse droplets resulting in a shear-thickening transition.

Developing upconversion nanoparticle-based smart substrates for remote temperature sensing

Science.gov (United States)

Coker, Zachary; Marble, Kassie; Alkahtani, Masfer; Hemmer, Philip; Yakovlev, Vladislav V.

2018-02-01

Recent developments in understanding of nanomaterial behaviors and synthesis have led to their application across a wide range of commercial and scientific applications. Recent investigations span from applications in nanomedicine and the development of novel drug delivery systems to nanoelectronics and biosensors. In this study, we propose the application of a newly engineered temperature sensitive water-based bio-compatible core/shell up-conversion nanoparticle (UCNP) in the development of a smart substrate for remote temperature sensing. We developed this smart substrate by dispersing functionalized nanoparticles into a polymer solution and then spin-coating the solution onto one side of a microscope slide to form a thin film substrate layer of evenly dispersed nanoparticles. By using spin-coating to deposit the particle solution we both create a uniform surface for the substrate while simultaneously avoid undesired particle agglomeration. Through this investigation, we have determined the sensitivity and capabilities of this smart substrate and conclude that further development can lead to a greater range of applications for this type smart substrate and use in remote temperature sensing in conjunction with other microscopy and spectroscopy investigations.

Nucleation of the lamellar phase from the disordered phase of the renormalized Landau-Brazovskii model

Science.gov (United States)

Carilli, Michael F.; Delaney, Kris T.; Fredrickson, Glenn H.

2018-02-01

Using the zero-temperature string method, we investigate nucleation of a stable lamellar phase from a metastable disordered phase of the renormalized Landau-Brazovskii model at parameters explicitly connected to those of an experimentally accessible diblock copolymer melt. We find anisotropic critical nuclei in qualitative agreement with previous experimental and analytic predictions; we also find good quantitative agreement with the predictions of a single-mode analysis. We conduct a thorough search for critical nuclei containing various predicted and experimentally observed defect structures. The predictions of the renormalized model are assessed by simulating the bare Landau-Brazovskii model with fluctuations. We find that the renormalized model makes reasonable predictions for several important quantities, including the order-disorder transition (ODT). However, the critical nucleus size depends sharply on proximity to the ODT, so even small errors in the ODT predicted by the renormalized model lead to large errors in the predicted critical nucleus size. We conclude that the renormalized model is a poor tool to study nucleation in the fluctuating Landau-Brazovskii model, and recommend that future studies work with the fluctuating bare model directly, using well-chosen collective variables to investigate kinetic pathways in the disorder → lamellar transition.

Microstructures and mechanical properties of directionally solidified Ni-25%Si full lamellar in situ composites

International Nuclear Information System (INIS)

Zhang, Binggang; Li, Xiaopeng; Wang, Ting; Liu, Zheng

2016-01-01

Directional solidification experiments have been performed on Ni-25 at% Si alloy using electron beam floating zone method. A fully regular eutectic microstructures consisting of Ni, γ-Ni 31 Si 12 and β 1 -Ni 3 Si have been obtained. The influences of the directional solidification rate on the microstructures and properties of the full lamellar structures have been studied. The results show that the relationship between the mean interphase spacing (λ) and withdrawal rate (v) meets λ=29.9v −0.65 . The hardness increases with the increasing of growth rate (v) and decreasing of the interlamellar spacing (λ) which meets the relationship of H V =445.2v 0.14 and H V =910λ −0.21 . The maximum compressive strength, 2576 MPa, for DS samples is obtained by 10 mm/h. The average fracture toughness value found for 5 mm/h, 7 mm/h, 10 mm/h is 28.3 MPa m 1/2 , 29.1 MPa m 1/2 and 35.9 MPa m 1/2 , respectively. The crack bridging and crack deflection/interface debonding are the main toughening mechanism of Ni-25 at% Si with full lamellar structures.

Suppression of coffee ring: (Particle) size matters

Science.gov (United States)

Bansal, Lalit; Seth, Pranjal; Murugappan, Bhubesh; Basu, Saptarshi

2018-05-01

Coffee ring patterns in drying sessile droplets are undesirable in various practical applications. Here, we experimentally demonstrate that on hydrophobic substrates, the coffee ring can be suppressed just by increasing the particle diameter. Particles with larger size flocculate within the evaporation timescale, leading to a significant gravimetric settling (for Pe > 1) triggering a uniform deposit. Interestingly, the transition to a uniform deposit is found to be independent of the internal flow field and substrate properties. Flocculation of particles also alters the particle packing at the nanoscale resulting in order to disorder transitions. In this letter, we exhibit a physical exposition on how particle size affects morphodynamics of the droplet drying at macro-nano length scales.

Queratitis lamelar difusa después de un corte incompleto Diffuse lamellar keratitis after incomplete corneal flap cut

Directory of Open Access Journals (Sweden)

Yanaisa Riverón Ruiz

2012-12-01

Full Text Available La queratitis lamelar difusa es una inflamación estéril de la interfase lamelar que suele presentarse 24 horas después de la realización de la queratomileusis in situ asistida con láser y potencialmente puede comprometer la agudeza visual final. Se presenta un paciente de 25 años de edad con antecedentes de cirugía refractiva corneal mediante queratomileusis in situ con láser en el ojo derecho, que tuvo como complicación durante el acto quirúrgico un corte incompleto. En el posoperatorio inmediato se le diagnosticó una queratitis lamelar difusa. Se aplicó tratamiento local y se obtuvo la recuperación visual total del paciente con estabilidad del defecto refractivo. Esto permite posteriormente realizarle la corrección mediante cirugía refractiva de superficie.The diffuse lamellar keratitis is a sterile swelling of the lamellar interface which arises generally 24 hours after laser in situ keratomileusis and might affect the final visual acuity. A 25 years- old patient with history of corneal refractive surgery by laser in situ keratomileusis on his right eye was reported. He suffered from an incomplete corneal flap cut as complication during the surgical procedure, and a diffuse lamellar keratitis was detected at the immediate postsurgical visit. Total visual recovery and the refractive defect stability were attained through local treatment. This allows further correcting the defect by means of a surface refractive surgery in the future.

Stochastic transport of particles across single barriers

International Nuclear Information System (INIS)

Kreuter, Christian; Siems, Ullrich; Henseler, Peter; Nielaba, Peter; Leiderer, Paul; Erbe, Artur

2012-01-01

Transport phenomena of interacting particles are of high interest for many applications in biology and mesoscopic systems. Here we present measurements on colloidal particles, which are confined in narrow channels on a substrate and interact with a barrier, which impedes the motion along the channel. The substrate of the particle is tilted in order for the particles to be driven towards the barrier and, if the energy gained by the tilt is large enough, surpass the barrier by thermal activation. We therefore study the influence of this barrier as well as the influence of particle interaction on the particle transport through such systems. All experiments are supported with Brownian dynamics simulations in order to complement the experiments with tests of a large range of parameter space which cannot be accessed in experiments.

Mammalian cell growth on gold nanoparticle-decorated substrates is influenced by the nanoparticle coating

Directory of Open Access Journals (Sweden)

Christina Rosman

2014-12-01

Full Text Available In this work, we study epithelial cell growth on substrates decorated with gold nanorods that are functionalized either with a positively charged cytotoxic surfactant or with a biocompatible polymer exhibiting one of two different end groups, resulting in a neutral or negative surface charge of the particle. Upon observation of cell growth for three days by live cell imaging using optical dark field microscopy, it was found that all particles supported cell adhesion while no directed cell migration and no significant particle internalization occurred. Concerning cell adhesion and spreading as compared to cell growth on bare substrates after 3 days of incubation, a reduction by 45% and 95%, respectively, for the surfactant particle coating was observed, whereas the amino-terminated polymer induced a reduction by 30% and 40%, respectively, which is absent for the carboxy-terminated polymer. Furthermore, interface-sensitive impedance spectroscopy (electric cell–substrate impedance sensing, ECIS was employed in order to investigate the micromotility of cells added to substrates decorated with various amounts of surfactant-coated particles. A surface density of 65 particles/µm2 (which corresponds to 0.5% of surface coverage with nanoparticles diminishes micromotion by 25% as compared to bare substrates after 35 hours of incubation. We conclude that the surface coating of the gold nanorods, which were applied to the basolateral side of the cells, has a recognizable influence on the growth behavior and thus the coating should be carefully selected for biomedical applications of nanoparticles.

Modeling of the rough spherical nanoparticles manipulation on a substrate based on the AFM nanorobot

Science.gov (United States)

Zakeri, M.; Faraji, J.

2014-12-01

In this paper, dynamic behavior of the rough spherical micro/nanoparticles during pulling/pushing on the flat substrate has been investigated and analyzed. For this purpose, at first, two hexagonal roughness models (George and Cooper) were studied and then evaluations for adhesion force were determined for rough particle manipulation on flat substrate. These two models were then changed by using of the Rabinovich theory. Evaluations were determined for contact adhesion force between rough particle and flat substrate; depth of penetration evaluations were determined by the Johnson-Kendall-Roberts contact mechanic theory and the Schwartz method and according to Cooper and George roughness models. Then, the novel contact theory was used to determine a dynamic model for rough micro/nanoparticle manipulation on flat substrate. Finally, simulation of particle dynamic behavior was implemented during pushing of rough spherical gold particles with radii of 50, 150, 400, 600, and 1,000 nm. Results derived from simulations of particles with several rates of roughness on flat substrate indicated that compared to results for flat particles, inherent roughness on particles might reduce the rate of critical force needed for sliding and rolling given particles. Given a fixed radius for roughness value and increased roughness height, evaluations for sliding and rolling critical forces showed greater reduction. Alternately, the rate of critical force was shown to reduce relative to an increased roughness radius. With respect to both models, based on the George roughness model, the predicted rate of adhesion force was greater than that determined in the Cooper roughness model, and as a result, the predicted rate of critical force based on the George roughness model was closer to the critical force value of flat particle.

Theory and simulation of epitaxial rotation. Light particles adsorbed on graphite

DEFF Research Database (Denmark)

Vives, E.; Lindgård, P.-A.

1993-01-01

We present a theory and Monte Carlo simulations of adsorbed particles on a corrugated substrate. We have focused on the case of rare gases and light molecules, H-2 and D2, adsorbed on graphite. The competition between the particle-particle and particle-substrate interactions gives rise to frustra...... found a modulated 4 x 4 structure. Energy, structure-factor intensities, peak positions, and epitaxial rotation angles as a function of temperature and coverage have been determined from the simulations. Good agreement with theory and experimental data is found.......We present a theory and Monte Carlo simulations of adsorbed particles on a corrugated substrate. We have focused on the case of rare gases and light molecules, H-2 and D2, adsorbed on graphite. The competition between the particle-particle and particle-substrate interactions gives rise...... between the commensurate and incommensurate phase for the adsorbed systems. From our simulations and our theory, we are, able to understand the gamma phase of D2 as an ordered phase stabilized by disorder. It can be described as a 2q-modulated structure. In agreement with the experiments, we have also...

Queratitis lamelar difusa después del Lasik Diffuse lamellar keratitis after LASIK

Directory of Open Access Journals (Sweden)

Lorelei Ortega Díaz

2010-12-01

Full Text Available OBJETIVO: Describir el comportamiento de la queratitis lamelar difusa como complicación después de emplear la técnica quirúrgica queratomileusis in situ con láser. MÉTODOS: Se realizó un estudio descriptivo, de corte transversal en el Servicio de Cirugía Refractiva Corneal del Instituto Cubano de Oftalmología "Ramón Pando Ferrer" en el último trimestre del año 2008. La muestra quedó conformada por 16 ojos a los que se les realizó la queratomileusis in situ con láser como técnica quirúrgica para corregir ametropía y que presentaron complicaciones con esta cirugía. Se analizaron variables como la agudeza visual sin corrección; los ojos con esta complicación fueron analizados según la clasificación de Linebarger. RESULTADOS: La frecuencia de queratitis lamelar difusa fue de 3,0 por cada 100. La agudeza visual no corregida se comportó entre 0,8 y 1,0 en 12 ojos de 16 afectados, el estadio 1 se presentó en 12 ojos. CONCLUSIONES: La queratitis lamelar difusa es una complicación poco frecuente, los casos que la padecieron alcanzaron una buena agudeza visual final sin corrección. Predominó la forma leve de este cuadro.OBJECTIVE: To describe the situation of Diffuse lamellar keratitis as a complication after in situ keratomileusis with laser. METHODS: A descriptive cross-sectional study was carried out in the Refractive Corneal Service of "Ramón Pando Ferrer" Cuban Institute of Ophthalmology during the last quarter of 2008. The sample embraced 16 eyes that underwent in situ keratomileusis plus laser as the refractive procedure to correct ametropy and presented with some complications. Visual acuity without correction was one the analyzed variables and the eyes with this type of complication were classified according to Linebarger´s classification. RESULTS: The diffuse lamellar keratitis frequency was 3.0 per one hundred cases, the visual acuity without correction was 0.8 to 1.0 in 12 out of 16 eyes whereas stage 1 was

Numerical study of melted particles crush metallic substrates and the interaction between particles and a plasma beam in the thermal projection process

International Nuclear Information System (INIS)

Kriba, Ilhem; Djebaili, A.

2009-01-01

Plasma spray processes have been widely used to produce high performance coatings of a wide range of materials (metallic, non-metallic, and ceramics), offering protection from, e.g. wear, extreme temperature, chemical attack and environmental corrosion. To obtain good quality coatings, spray parameters must be carefully selected. Due to the large variety in process parameters, it is difficult to optimize the process for each specific coating and substrate combinations. Furthermore modelling the spray process allows a better understanding of the process sequences during thermal spraying. The simulation of coating formation to estimate the process parameters is an important tool to develop new coating structures with defined properties. In this work, the process of plasma sprayed coating has been analyzed by numerical simulation. Commercial code is used to predict the plasma jet characteristics, plasma-particle interaction, and coating formation. Using this model we can obtain coating microstructure and characteristics which form a foundation for further improvement of an advanced ceramic coating build up model

Targeted inactivation of the murine Abca3 gene leads to respiratory failure in newborns with defective lamellar bodies

International Nuclear Information System (INIS)

Hammel, Markus; Michel, Geert; Hoefer, Christina; Klaften, Matthias; Mueller-Hoecker, Josef; Angelis, Martin Hrabe de; Holzinger, Andreas

2007-01-01

Mutations in the human ABCA3 gene, encoding an ABC-transporter, are associated with respiratory failure in newborns and pediatric interstitial lung disease. In order to study disease mechanisms, a transgenic mouse model with a disrupted Abca3 gene was generated by targeting embryonic stem cells. While heterozygous animals developed normally and were fertile, individuals homozygous for the altered allele (Abca3-/-) died within one hour after birth from respiratory failure, ABCA3 protein being undetectable. Abca3-/- newborns showed atelectasis of the lung in comparison to a normal gas content in unaffected or heterozygous littermates. Electron microscopy demonstrated the absence of normal lamellar bodies in type II pneumocytes. Instead, condensed structures with apparent absence of lipid content were found. We conclude that ABCA3 is required for the formation of lamellar bodies and lung surfactant function. The phenotype of respiratory failure immediately after birth corresponds to the clinical course of severe ABCA3 mutations in human newborns

Electroclinic effect in the chiral lamellar α phase of a lyotropic liquid crystal

Science.gov (United States)

Harjung, Marc D.; Giesselmann, Frank

2018-03-01

In thermotropic chiral Sm -A* phases, an electric field along the smectic layers breaks the D∞ symmetry of the Sm -A* phase and induces a tilt of the liquid crystal director. This so-called electroclinic effect (ECE) was first reported by Garoff and Meyer in 1977 and attracted substantial scientific and technological interest due to its linear and submicrosecond electro-optic response [S. Garoff and R. B. Meyer, Phys. Rev. A 19, 338 (1979), 10.1103/PhysRevA.19.338]. We now report the observation of an ECE in the pretransitional regime from a lyotropic chiral lamellar Lα* phase into a lyo-Sm -C* phase, the lyotropic analog to the thermotropic Sm -C* phase which was recently discovered by Bruckner et al. [Angew. Chem. Int. Ed. 52, 8934 (2013), 10.1002/anie.201303344]. We further show that the observed ECE has all signatures of its thermotropic counterpart, namely (i) the effect is chiral in nature and vanishes in the racemic Lα phase, (ii) the effect is essentially linear in the sign and magnitude of the electric field, and (iii) the magnitude of the effect diverges hyperbolically as the temperature approaches the critical temperature of the second order tilting transition. Specific deviations between the ECEs in chiral lamellar and chiral smectic phases are related to the internal field screening effect of electric double layers formed by inevitable ionic impurities in lyotropic phases.

Some aspects of lamellar structure in various green leaf particles, indicated by oleic acid effects

NARCIS (Netherlands)

Terpstra, Willem

1. (1) The influence of oleic acid on “whole chloroplasts and large fragments”, isolated from spinach or endive leaves, was compared to that on Photosystem I (PS I) and PS I+II particles, probably stroma lamellae, isolated from the same leaves. 2. (2) Photochemical activity (Hill reaction and

Recycled hydroxyapatite coatings on 316L stainless steel substrates

International Nuclear Information System (INIS)

Mendes Filho, Antonio Alves; Pereira, Renato Alves; Araujo, Fernando Gabriel da Silva; Sousa, Camila Mateus de

2010-01-01

In this work were evaluated recycled hydroxyapatite coatings on 316L stainless steel substrates by plasma thermal aspersion. The hydroxyapatite used was obtained from bovine bone by the hydrothermal method. The samples of hydroxyapatite powders were divided according to their particle size distribution. The adhesion of the powders coating to the substrate was evaluated by assay scratch. The X-ray diffraction techniques and scanning electron microscopy were also used. The results of scratch resistance were between 46N and 63N. Analysis by scanning electron microscopy and x-ray diffraction showed no cracks coatings, single-phase and with few fused particles. (author)

The deformation twin in lamellar Ti 3Al/TiAl structure

Science.gov (United States)

Zhang, J. X.; Ye, H. Q.

2003-04-01

A Ti-48Al-2Cr (at.%) alloy consisting of γ+α 2 lamellar structure was deformed in compression at room temperature. Study by high resolution electron microscopy was carried out on the characteristic of induced γ T/α 2 interface. During deformation the γ T/α 2 interface presents a stepped structure and the γ/α 2 interface remains straight. The formation mechanism of γ T associated with misfit dislocations is proposed. 1/2[01 1¯] γ interfacial dislocation in the γ/α 2 interface can dissociate into a 1/6[ 1¯1 2¯] γ partial dislocation which glides on the ( 1¯11) γ plane and causes γ T to form.

Multipulse NMR study of the lamellar mesophase of some liquid crystals

International Nuclear Information System (INIS)

Jasinski, A.; Morris, P.G.; Mansfield, P.

1977-01-01

Multipulse NMR techniques have been used to investigate the dynamic jproperties of cesium perfluoro-octanoate (CsPFO) and ammonium perfluoro-octanoate (APFO) + water systems, which are liquid crystals, over a wide range of temperautre and concentration. Axially symmetric fluorine chemical shift tensors have been measured for the CF 2 and CF 3 groups by performing a rotation study of an aligned sample (50% CsPFO : 50% D 2 O) at room temperature. The order parameter S in the lamellar mesophase of 72,2% CsPFO : 27,8% D 2 O and 70% APFO : 30% D 2 O has been obtained over as temperature range 20 0 C - 85 0 C by fitting the multipulse spectra. (author)

Metal oxide nanorod arrays on monolithic substrates

Energy Technology Data Exchange (ETDEWEB)

Gao, Pu-Xian; Guo, Yanbing; Ren, Zheng

2018-01-02

A metal oxide nanorod array structure according to embodiments disclosed herein includes a monolithic substrate having a surface and multiple channels, an interface layer bonded to the surface of the substrate, and a metal oxide nanorod array coupled to the substrate surface via the interface layer. The metal oxide can include ceria, zinc oxide, tin oxide, alumina, zirconia, cobalt oxide, and gallium oxide. The substrate can include a glass substrate, a plastic substrate, a silicon substrate, a ceramic monolith, and a stainless steel monolith. The ceramic can include cordierite, alumina, tin oxide, and titania. The nanorod array structure can include a perovskite shell, such as a lanthanum-based transition metal oxide, or a metal oxide shell, such as ceria, zinc oxide, tin oxide, alumina, zirconia, cobalt oxide, and gallium oxide, or a coating of metal particles, such as platinum, gold, palladium, rhodium, and ruthenium, over each metal oxide nanorod. Structures can be bonded to the surface of a substrate and resist erosion if exposed to high velocity flow rates.

Solvation thermodynamics of phenylalcohols in lamellar phase surfactant dispersions

International Nuclear Information System (INIS)

Martyniak, A.; Scheuermann, R.; Dilger, H.; Tucker, I.M.; Burkert, T.; Hashmi, A.S.K.; Vujosevic', D.; Roduner, E.

2006-01-01

The distribution and the stability of five phenylalcohols in a lamellar phase composed of simple bilayers separated by water at 298 and 348K is explored using avoided-level-crossing muon-spin resonance (ALC-μSR). The dependence of the alignment of the bilayer chains on temperature appears to be a crucial factor determining the phenylalcohol partitioning: increasing order of the surfactant tails leads to expulsion of the solute. Moreover, we observed a systematic trend, the longer the chain the deeper the phenyl group dips into the lipid bilayer. Recent studies have shown that the hydrophobic effect is adequate to describe membrane partitioning of small amphiphilic molecules. The solvation thermodynamic properties ΔG sol , ΔH sol , and ΔS sol which determine the solute transfer from the double layer into water prove that the distribution also strongly depends on shape, chemical nature and different structure of phenylalcohols

Solvation thermodynamics of phenylalcohols in lamellar phase surfactant dispersions

Energy Technology Data Exchange (ETDEWEB)

Martyniak, A. [Institut fuer Physikalische Chemie, University of Stuttgart, Pfaffenwaldring 55, D-70569 Stuttgart (Germany); Scheuermann, R. [Laboratory for muon Spin Spectroscopy, Paul Scherrer Institute, CH-5232 Villigen (Switzerland); Dilger, H. [Institut fuer Physikalische Chemie, University of Stuttgart, Pfaffenwaldring 55, D-70569 Stuttgart (Germany); Tucker, I.M. [Unilever Research and Development, Port Sunlight, Wirral CH63 3JW (United Kingdom); Burkert, T. [Institut fuer Organische Chemie, University of Stuttgart, Pfaffenwaldring 55, D-70569 Stuttgart (Germany); Hashmi, A.S.K. [Institut fuer Organische Chemie, University of Stuttgart, Pfaffenwaldring 55, D-70569 Stuttgart (Germany); Vujosevic' , D. [Institut fuer Physikalische Chemie, University of Stuttgart, Pfaffenwaldring 55, D-70569 Stuttgart (Germany); Roduner, E. [Institut fuer Physikalische Chemie, University of Stuttgart, Pfaffenwaldring 55, D-70569 Stuttgart (Germany)]. E-mail: e.roduner@ipc.uni-stuttgart.de

2006-03-31

The distribution and the stability of five phenylalcohols in a lamellar phase composed of simple bilayers separated by water at 298 and 348K is explored using avoided-level-crossing muon-spin resonance (ALC-{mu}SR). The dependence of the alignment of the bilayer chains on temperature appears to be a crucial factor determining the phenylalcohol partitioning: increasing order of the surfactant tails leads to expulsion of the solute. Moreover, we observed a systematic trend, the longer the chain the deeper the phenyl group dips into the lipid bilayer. Recent studies have shown that the hydrophobic effect is adequate to describe membrane partitioning of small amphiphilic molecules. The solvation thermodynamic properties {delta}G{sub sol}, {delta}H{sub sol}, and {delta}S{sub sol} which determine the solute transfer from the double layer into water prove that the distribution also strongly depends on shape, chemical nature and different structure of phenylalcohols.

Conductivity of an inverse lyotropic lamellar phase under shear flow

Science.gov (United States)

Panizza, P.; Soubiran, L.; Coulon, C.; Roux, D.

2001-08-01

We report conductivity measurements on solutions of closed compact monodisperse multilamellar vesicles (the so-called ``onion texture'') formed by shearing an inverse lyotropic lamellar Lα phase. The conductivity measured in different directions as a function of the applied shear rate reveals a small anisotropy of the onion structure due to the existence of free oriented membranes. The results are analyzed in terms of a simple model that allows one to deduce the conductivity tensor of the Lα phase itself and the proportion of free oriented membranes. The variation of these two parameters is measured along a dilution line and discussed. The high value of the conductivity perpendicular to the layers with respect to that of solvent suggests the existence of a mechanism of ionic transport through the insulating solvent.

Porous Chromatographic Materials as Substrates for Preparing Synthetic Nuclear Explosion Debris Particles

International Nuclear Information System (INIS)

Harvey, Scott D.; Liezers, Martin; Antolick, Kathryn C.; Garcia, Ben J.; Sweet, Lucas E.; Carman, April J.; Eiden, Gregory C.

2013-01-01

In this study, we investigated several porous chromatographic materials as synthetic substrates for preparing surrogate nuclear explosion debris particles. The resulting synthetic debris materials are of interest for use in developing analytical methods. Eighteen metals, including some of forensic interest, were loaded onto materials by immersing them in metal solutions (556 mg/L of each metal) to fill the pores, applying gentle heat (110°C) to drive off water, and then treating them at high temperatures (up to 800°C) in air to form less soluble metal species. High-boiling-point metals were uniformly loaded on spherical controlled-pore glass to emulate early fallout, whereas low-boiling-point metals were loaded on core-shell silica to represent coated particles formed later in the nuclear fallout-formation process. Analytical studies were applied to characterize solubility, material balance, and formation of recalcitrant species. Dissolution experiments indicated loading was 1.5 to 3 times higher than expected from the pore volume alone, a result attributed to surface coating. Analysis of load solutions before and after filling the material pores revealed that most metals were passively loaded; that is, solutions filled the pores without active metal discrimination. However, niobium and tin concentrations were lower in solutions after pore filling, and were found in elevated concentrations in the final products, indicating some metals were selectively loaded. High-temperature treatments caused reduced solubility of several metal species, and loss of some metals (rhenium and tellurium) because volatile species were formed. Sample preparation reproducibility was high (the inter-batch relative standard deviation was 7.8%, and the intra-batch relative standard deviation was 0.84%) indicating that this material is suitable for use as a working standard for analytical methods development. We anticipate future standardized radionuclide-loaded materials will find use in

Manufacturing Process for OLED Integrated Substrate

Energy Technology Data Exchange (ETDEWEB)

Hung, Cheng-Hung [Vitro Flat Glass LLC, Cheswick, PA (United States). Glass Technology Center

2017-03-31

The main objective of this project was to develop a low-cost integrated substrate for rigid OLED solid-state lighting produced at a manufacturing scale. The integrated substrates could include combinations of soda lime glass substrate, light extraction layer, and an anode layer (i.e., Transparent Conductive Oxide, TCO). Over the 3⁺ year course of the project, the scope of work was revised to focus on the development of a glass substrates with an internal light extraction (IEL) layer. A manufacturing-scale float glass on-line particle embedding process capable of producing an IEL glass substrate having a thickness of less than 1.7mm and an area larger than 500mm x 400mm was demonstrated. Substrates measuring 470mm x 370mm were used in the OLED manufacturing process for fabricating OLED lighting panels in single pixel devices as large as 120.5mm x 120.5mm. The measured light extraction efficiency (calculated as external quantum efficiency, EQE) for on-line produced IEL samples (>50%) met the project’s initial goal.

Biaxial mechanics and inter-lamellar shearing of stem-cell seeded electrospun angle-ply laminates for annulus fibrosus tissue engineering.

Science.gov (United States)

Driscoll, Tristan P; Nakasone, Ryan H; Szczesny, Spencer E; Elliott, Dawn M; Mauck, Robert L

2013-06-01

The annulus fibrosus (AF) of the intervertebral disk plays a critical role in vertebral load transmission that is heavily dependent on the microscale structure and composition of the tissue. With degeneration, both structure and composition are compromised, resulting in a loss of AF mechanical function. Numerous tissue engineering strategies have addressed the issue of AF degeneration, but few have focused on recapitulation of AF microstructure and function. One approach that allows for generation of engineered AF with appropriate (+/-)30° lamellar microstructure is the use of aligned electrospun scaffolds seeded with mesenchymal stem cells (MSCs) and assembled into angle-ply laminates (APL). Previous work indicates that opposing lamellar orientation is necessary for development of near native uniaxial tensile properties. However, most native AF tensile loads are applied biaxially, as the disk is subjected to multi-axial loads and is constrained by its attachments to the vertebral bodies. Thus, the objective of this study was to evaluate the biaxial mechanical response of engineered AF bilayers, and to determine the importance of opposing lamellar structure under this loading regime. Opposing bilayers, which replicate native AF structure, showed a significantly higher modulus in both testing directions compared to parallel bilayers, and reached ∼60% of native AF biaxial properties. Associated with this increase in biaxial properties, significantly less shear, and significantly higher stretch in the fiber direction, was observed. These results provide additional insight into native tissue structure-function relationships, as well as new benchmarks for engineering functional AF tissue constructs. Copyright © 2013 Orthopaedic Research Society.

A METHOD FOR PREPARING A SUBSTRATE BY APPLYING A SAMPLE TO BE ANALYSED

DEFF Research Database (Denmark)

2017-01-01

The invention relates to a method for preparing a substrate (105a) comprising a sample reception area (110) and a sensing area (111). The method comprises the steps of: 1) applying a sample on the sample reception area; 2) rotating the substrate around a predetermined axis; 3) during rotation......, at least part of the liquid travels from the sample reception area to the sensing area due to capillary forces acting between the liquid and the substrate; and 4) removing the wave of particles and liquid formed at one end of the substrate. The sensing area is closer to the predetermined axis than...... the sample reception area. The sample comprises a liquid part and particles suspended therein....

New Development in Selective Laser Melting of Ti-6Al-4V: A Wider Processing Window for the Achievement of Fully Lamellar α + β Microstructures

Science.gov (United States)

Lui, E. W.; Xu, W.; Pateras, A.; Qian, M.; Brandt, M.

2017-12-01

Recent progress has shown that Ti-6Al-4V fabricated by selective laser melting (SLM) can achieve a fully lamellar α + β microstructure using 60 µm layer thickness in the as-built state via in situ martensite decomposition by manipulating the processing parameters. The potential to broaden the processing window was explored in this study by increasing the layer thickness to the less commonly used 90 µm. Fully lamellar α + β microstructures were produced in the as-built state using inter-layer times in the range of 1-12 s. Microstructural features such as the α-lath thickness and morphology were sensitive to both build height and inter-layer time. The α-laths produced using the inter-layer time of 1 s were much coarser than those produced with the inter-layer time of 12 s. The fine fully lamellar α + β structure resulted in tensile ductility of 11% and yield strength of 980 MPa. The tensile properties can be further improved by minimizing the presence of process-induced defects.

Theory of the ellipsometry of a layer of semiconductor nanoparticles covering the substrate

International Nuclear Information System (INIS)

Borshchagyivs'kij, Je.G.; Lozovs'kij, V.Z.; Lozovs'kij, V.Z.; Myishakova, T.O.

2010-01-01

A theoretical model of ellipsometry of a submonolayer of semiconductor nanoparticles on a surface is built in the frame of the local field method. We calculated the effective susceptibility of the system which had been modeled as a substrate with ellipsoidal particles. These calculations allow us to determine the reflection coefficients and the ellipsometric parameters versus the wavelength and the angle of incidence. It is shown that semiconductor particles on a substrate give a measurable contribution to ellipsometric parameters. We obtain that ellipsometric parameters depend on the concentration and the shape of particles.

Study of crack propagation mechanisms during Charpy impact toughness tests on both equiaxed and lamellar microstructures of Ti–6Al–4V titanium alloy

Energy Technology Data Exchange (ETDEWEB)

Buirette, Christophe, E-mail: christophe.buirette@ensiacet.fr [Institut Carnot CIRIMAT, ENSIACET, 4 allée Emile Monso, 31030 Toulouse (France); Huez, Julitte, E-mail: julitte.huez@ensiacet.fr [Institut Carnot CIRIMAT, ENSIACET, 4 allée Emile Monso, 31030 Toulouse (France); Gey, Nathalie, E-mail: Nathalie.gey@univ-lorraine.fr [Laboratoire d’Etude des Microstructures et de Mécanique des Matériaux (LEM3), UMR CNRS 7239, Université de Lorraine, Île du Saulcy, 57045 METZ Cedex 1 (France); DAMAS, Laboratory of Excellence on Design of Alloy Metals for Low-Mass Structures, Université de Lorraine (France); Vassel, Alain, E-mail: alain.vassel@titane.asso.fr [Association Française du Titane, 16 quai Ernest Renaud, BP 70515, 44105 Nantes Cedex 4 (France); Andrieu, Eric, E-mail: eric.andrieu@ensiacet.fr [Institut Carnot CIRIMAT, ENSIACET, 4 allée Emile Monso, 31030 Toulouse (France)

2014-11-17

The impact toughness of two highly textured rolled plates of Ti–6Al–4V alloy with an α equiaxed and an α lamellar microstructures has been investigated. The results show a strong anisotropy of the fracture energy for both materials and underline that a coincidence of the prismatic planes with the shear bands at the notch tip is favorable for higher fracture energies. Moreover, it is pointed out, as it was already done by previous studies, that the α lamellar microstructure presents higher fracture energy than the α equiaxed one. Thanks to electron back scattering diffraction, and tensile tests, local microstructure heterogeneities, called macrozones, have been observed and characterized. Their size depends on microstructure element and is larger for α lamellar microstructure than for the α equiaxed. High strain is localized on the macrozones favorably oriented for prismatic slip with respect to the direction of impact and leads to a particular dimple free zone on the fracture surface. The contribution of these macrozones in the fracture behavior, and more precisely on the crack propagation rate was evaluated; thus the effects of the macroscopic texture and of the microstructure element on the impact toughness are discussed separately.

Gold nano-particles fixed on glass

International Nuclear Information System (INIS)

Worsch, Christian; Wisniewski, Wolfgang; Kracker, Michael; Rüssel, Christian

2012-01-01

Highlights: ► We produced wear resistant gold–ruby coatings on amorphous substrates. ► Thin sputtered gold layers were covered by or embedded in silica coatings. ► Annealing above T g of the substrate glass led to the formation of gold nano particles. ► A 1 1 1-texture of the gold particles is observed via XRD and EBSD. ► EBSD-patterns can be acquired from crystals covered by a thin layer of glass. - Abstract: A simple process for producing wear resistant gold nano-particle coatings on transparent substrates is proposed. Soda-lime-silica glasses were sputtered with gold and subsequently coated with SiO 2 using a combustion chemical vapor deposition technique. Some samples were first coated with silica, sputtered with gold and then coated with a second layer of silica. The samples were annealed for 20 min at either 550 or 600 °C. This resulted in the formation of round, well separated gold nano-particles with sizes from 15 to 200 nm. The color of the coated glass was equivalent to that of gold–ruby glasses. Silica/gold/silica coatings annealed at 600 °C for 20 min were strongly adherent and scratch resistant. X-ray diffraction and electron backscatter diffraction (EBSD) were used to describe the crystal orientations of the embedded particles. The gold particles are preferably oriented with their (1 1 1) planes perpendicular to the surface.

Entropy-driven crystal formation on highly strained substrates

KAUST Repository

Savage, John R.

2013-05-20

In heteroepitaxy, lattice mismatch between the deposited material and the underlying surface strongly affects nucleation and growth processes. The effect of mismatch is well studied in atoms with growth kinetics typically dominated by bond formation with interaction lengths on the order of one lattice spacing. In contrast, less is understood about how mismatch affects crystallization of larger particles, such as globular proteins and nanoparticles, where interparticle interaction energies are often comparable to thermal fluctuations and are short ranged, extending only a fraction of the particle size. Here, using colloidal experiments and simulations, we find particles with short-range attractive interactions form crystals on isotropically strained lattices with spacings significantly larger than the interaction length scale. By measuring the free-energy cost of dimer formation on monolayers of increasing uniaxial strain, we show the underlying mismatched substrate mediates an entropy-driven attractive interaction extending well beyond the interaction length scale. Remarkably, because this interaction arises from thermal fluctuations, lowering temperature causes such substrate-mediated attractive crystals to dissolve. Such counterintuitive results underscore the crucial role of entropy in heteroepitaxy in this technologically important regime. Ultimately, this entropic component of lattice mismatched crystal growth could be used to develop unique methods for heterogeneous nucleation and growth of single crystals for applications ranging from protein crystallization to controlling the assembly of nanoparticles into ordered, functional superstructures. In particular, the construction of substrates with spatially modulated strain profiles would exploit this effect to direct self-assembly, whereby nucleation sites and resulting crystal morphology can be controlled directly through modifications of the substrate.

Depositing nanometer-sized particles of metals onto carbon allotropes

Science.gov (United States)

Watson, Kent A. (Inventor); Fallbach, Michael J. (Inventor); Ghose, Sayata (Inventor); Smith, Joseph G. (Inventor); Delozier, Donavon M. (Inventor); Connell, John W. (Inventor)

2010-01-01

A process for depositing nanometer-sized metal particles onto a substrate in the absence of aqueous solvents, organic solvents, and reducing agents, and without any required pre-treatment of the substrate, includes preparing an admixture of a metal compound and a substrate by dry mixing a chosen amount of the metal compound with a chosen amount of the substrate; and supplying energy to the admixture in an amount sufficient to deposit zero valance metal particles onto the substrate. This process gives rise to a number of deposited metallic particle sizes which may be controlled. The compositions prepared by this process are used to produce polymer composites by combining them with readily available commodity and engineering plastics. The polymer composites are used as coatings, or they are used to fabricate articles, such as free-standing films, fibers, fabrics, foams, molded and laminated articles, tubes, adhesives, and fiber reinforced articles. These articles are well-suited for many applications requiring thermal conductivity, electrical conductivity, antibacterial activity, catalytic activity, and combinations thereof.

Investigations of mussel-inspired polydopamine deposition on WC and Al{sub 2}O{sub 3} particles: The influence of particle size and material

Energy Technology Data Exchange (ETDEWEB)

Mondin, Giovanni, E-mail: giovanni.mondin@chemie.tu-dresden.de [Department of Inorganic Chemistry, Dresden University of Technology, Bergstrasse 66, 01069 Dresden (Germany); Haft, Marcel, E-mail: m.haft@ifw-dresden.de [Leibniz Institute for Solid State and Materials Research (IFW) Dresden, Institute for Solid State Research, Helmholtzstr. 20, 01069 Dresden (Germany); Wisser, Florian M., E-mail: florian.wisser@chemie.tu-dresden.de [Department of Inorganic Chemistry, Dresden University of Technology, Bergstrasse 66, 01069 Dresden (Germany); Leifert, Annika, E-mail: annika.leifert@chemie.tu-dresden.de [Department of Inorganic Chemistry, Dresden University of Technology, Bergstrasse 66, 01069 Dresden (Germany); Mohamed-Noriega, Nasser, E-mail: nasser.mohamed-noriega@chemie.tu-dresden.de [Department of Inorganic Chemistry, Dresden University of Technology, Bergstrasse 66, 01069 Dresden (Germany); Dörfler, Susanne, E-mail: susanne.doerfler@chemie.tu-dresden.de [Department of Inorganic Chemistry, Dresden University of Technology, Bergstrasse 66, 01069 Dresden (Germany); Hampel, Silke, E-mail: s.hampel@ifw-dresden.de [Leibniz Institute for Solid State and Materials Research (IFW) Dresden, Institute for Solid State Research, Helmholtzstr. 20, 01069 Dresden (Germany); Grothe, Julia, E-mail: stefan.kaskel@chemie.tu-dresden.de [Department of Inorganic Chemistry, Dresden University of Technology, Bergstrasse 66, 01069 Dresden (Germany); Kaskel, Stefan, E-mail: julia.grothe@chemie.tu-dresden.de [Department of Inorganic Chemistry, Dresden University of Technology, Bergstrasse 66, 01069 Dresden (Germany)

2014-12-15

Polydopamine, formed by oxidation of dopamine, is a bioinspired polymer developed for multifunctional coatings by Lee et al. in 2007 by drawing inspiration from the adhesive proteins found in mussels. Due to their high versatility and substrate-independence, polydopamine coatings are gaining considerable attention in a plethora of research fields, particularly in the coating of particles, but systematic investigations of the polydopamine coating process are lacking in the literature. In this study, we explore by TEM and thermogravimetric analysis the polydopamine coating process on alumina microparticles, tungsten carbide microparticles and tungsten carbide nanoparticles. By choosing two substrates with similar size but different material (Al{sub 2}O{sub 3} and WC), as well as two substrates of the same material but different size (WC micro- and nanoparticles) we investigate the effects of both substrate material and substrate size, in order to gain some insights into the polydopamine particle coating process. As opposed to what is generally assumed in the literature, we found that the polydopamine coating thicknesses on particles, as well as the thickness growing trend, depend on the particles size and material. In particular, after 24 h of polymerization time the polydopamine coatings reached a thickness of 65 ± 10 nm in the case of Al{sub 2}O{sub 3} microparticles, 18 ± 4 nm in the case of WC microparticles and 33 ± 6 nm in the case of WC nanoparticles. - Highlights: • The coating of different particles with polydopamine was systematically investigated. • Al{sub 2}O{sub 3} microparticles and WC microparticles and nanoparticles were investigated. • The thickness of the polydopamine coating depends on the particle size. • The thickness of the polydopamine coating depends on the particle material.

The Evolution of Splint Armour in Georgia and Byzantium: Lamellar and Scale Armour in the 10th-12th Centuries

Directory of Open Access Journals (Sweden)

Mamuka TSURTSUMIA

2011-10-01

Full Text Available Byzantine technology was part of the military technology that existed in vast areas of Eurasia; hence study of the armament of its neighbours is important.The purpose of the present paper is to add new data about Byzantium’s Caucasian neighbour (namely, Georgia. Besides that, it also includes certain views about the stages of the evolution and provenance of splint (scale and lamellar armour. This paper also attempts to clarify the difference between banded and linear suits of lamellar armour.There is no doubt that the Byzantine military machine exercised considerable influence on its neighbours, though an opposite phenomenon can also be noticed. The article shows that changes in armour were taking place almost simultaneously in the Byzantine Empire and the Georgian kingdoms and that some of the types of armour that were widespread in Byzantium may have originated in Georgia.

Multiscale Simulations of Lamellar PS–PEO Block Copolymers Doped with LiPF6 Ions

KAUST Repository

Sethuraman, Vaidyanathan

2017-06-02

We report the results of atomistic simulations of the structural equilibrium properties of PS–PEO block copolymer (BCP) melt in the ordered lamellar phase doped with LiPF6 salt. A hybrid simulation strategy, consisting of steps of coarse-graining and inverse coarse-graining, was employed to equilibrate the melt at an atomistic resolution in the ordered phase. We characterize the structural distributions between different atoms/ions and compare the features arising in BCPs against the corresponding behavior in PEO homopolymers for different salt concentrations. In addition, the local structural distributions are characterized in the lamellar phase as a function of distance from the interface. The cation–anion radial distribution functions (RDF) display stronger coordination in the block copolymer melts at high salt concentrations, whereas the trends are reversed for low salt concentrations. Radial distribution functions isolated in the PEO and PS domains demonstrate that the stronger coordination seen in BCPs arises from the influence of both the higher fraction of ions segregated in the PS phase and the influence of interactions in the PS domain. Such a behavior also manifests in the cation–anion clusters, which show a larger fraction of free ions in the BCP. While the average number of free anions (cations) decreases with increasing salt concentration, higher order aggregates of LiPF6 increase with increasing salt concentration. Further, the cation–anion RDFs display spatial heterogeneity, with a stronger cation–anion binding in the interfacial region compared to bulk of the PEO domain.

A comparison study of rhodamine B photodegradation over nitrogen-doped lamellar niobic acid and titanic acid under visible-light irradiation.

Science.gov (United States)

Li, Xiukai; Kikugawa, Naoki; Ye, Jinhua

2009-01-01

A solid-state reaction method with urea as a nitrogen precursor was used to prepare nitrogen-doped lamellar niobic and titanic solid acids (i.e., HNb(3)O(8) and H(2)Ti(4)O(9)) with different acidities for visible-light photocatalysis. The photocatalytic activities of the nitrogen-doped solid acids were evaluated for rhodamine B (RhB) degradation and the results were compared with those obtained over the corresponding nitrogen-doped potassium salts. Techniques such as XRD, BET, SEM, X-ray photoelectron spectroscopy, and UV-visible diffuse reflectance spectroscopy were adopted to explore the nature of the materials as well as the characteristics of the doped nitrogen species. It was found that the intercalation of the urea precursor helped to stabilize the layered structures of both lamellar solid acids and enabled easier nitrogen doping. The effects of urea intercalation were more significant for the more acidic HNb(3)O(8) sample than for the less acidic H(2)Ti(4)O(9). Compared with the nitrogen-doped KNb(3)O(8) and K(2)Ti(4)O(9) samples, the nitrogen-doped HNb(3)O(8) and H(2)Ti(4)O(9) solid acids absorb more visible light and exhibit a superior activity for RhB photodegradation under visible-light irradiation. The nitrogen-doped HNb(3)O(8) sample performed the best among all the samples. The results of the current study suggest that the protonic acidity of the lamellar solid-acid sample is a key factor that influences nitrogen doping and the resultant visible-light photocatalysis.

Epiretinal proliferation in lamellar macular holes and full-thickness macular holes: clinical and surgical findings.

Science.gov (United States)

Lai, Tso-Ting; Chen, San-Ni; Yang, Chung-May

2016-04-01

To report the clinical findings and surgical outcomes of lamellar macular holes (LMH) with or without lamellar hole-associated epiretinal proliferation (LHEP), and those of full-thickness macular holes (FTMH) presenting with LHEP. From 2009 to 2013, consecutive cases of surgically treated LMH, and all FTMH cases with LHEP were reviewed, given a follow-up time over 1 year. In the LMH group (43 cases), those with LHEP (19 cases) had significantly thinner bases and larger openings than those without (24 cases). The rate of disrupted IS/OS line was higher in the LHEP subgroup preoperatively (68.4 % vs 37.5 %), but similar between subgroups postoperatively (36.8 % and 33.3 %). The preoperative and postoperative visual acuity showed no significant difference between two subgroups. In the FTMH group (13 cases), the average hole size was 219.2 ± 92.1 μm. Permanent or transient spontaneous hole closure was noted in 69.2 % of cases. An intact IS-OS line was found in only 23 % of cases at the final follow-up. In the LMH group, LHEP was associated with a more severe defect but didn't affect surgical outcomes. In the FTMH group, spontaneous hole closure was frequently noted. Despite small holes, disruption of IS-OS line was common after hole closure.

Morphology determination of small particles by electron microscopy and electrical conduction measurements

International Nuclear Information System (INIS)

Robrieux, B.; Desrousseaux, G.; Renou, A.; Gillet, M.

1989-01-01

In this paper, we show that it is possible to deduce the actual morphology of small particle condensed onto an insulator by combining the granularity analysis from electron micrographs and the electrical sheet conductance of the deposit on its substrate. Assuming the particles are truncated ellipsoids, we determine the excentricity and the contact angle with the substrate for Au on amorphous carbon and MgO substrates. (orig.)

Instability of a Lamellar Phase under Shear Flow: Formation of Multilamellar Vesicles

Science.gov (United States)

Courbin, L.; Delville, J. P.; Rouch, J.; Panizza, P.

2002-09-01

The formation of closed-compact multilamellar vesicles (referred to in the literature as the ``onion texture'') obtained upon shearing lamellar phases is studied using small-angle light scattering and cross-polarized microscopy. By varying the shear rate γ ˙, the gap cell D, and the smectic distance d, we show that: (i)the formation of this structure occurs homogeneously in the cell at a well-defined wave vector qi, via a strain-controlled process, and (ii)the value of qi varies as (dγ ˙/D)1/3. These results strongly suggest that formation of multilamellar vesicles may be monitored by an undulation (buckling) instability of the membranes, as expected from theory.

A case of acute postoperative keratitis after deep anterior lamellar keratoplasty by multidrug resistant Klebsiella

Directory of Open Access Journals (Sweden)

Leena Bajracharya

2015-01-01

Full Text Available A healthy lady of 42 years underwent deep anterior lamellar keratoplasty for granular dystrophy. The very next day, it was complicated by development of infectious keratitis. The organism was identified as multidrug resistant Klebsiella pneumoniae. Donor corneal button may be implicated in the transmission of infection in an otherwise uneventful surgery and follow-up. Nosocomial infections are usually severe, rapidly progressive and difficult to treat. Finally, the lady had to undergo therapeutic penetrating keratoplasty for complete resolution of infection.

Phase-field model for deposition process of platinum nanoparticles on carbon substrate

International Nuclear Information System (INIS)

Yamakawa, S; Hyodo, S; Okazaki-Maeda, K; Kohyama, M

2008-01-01

Platinum supported on a carbon carrier is widely used as a catalyst for polymer electrolyte membrane fuel cells. The catalytic activity is significantly affected by the size distribution and morphologies of the platinum particles. The objective of this study is to extend the phase-field approach to describe the formation process of platinum particles onto the substrate. The microstructural evolution of a nanoparticle was represented by the temporal evolution of the field variables related to the platinum concentration, long-range crystallographic ordering and phase transition. First-principles calculations were performed in order to estimate the interaction energies between several different types of platinum clusters and a graphene sheet. The platinum density profile concentrated over the substrate surface led to the formation of three-dimensional islands in accordance with the Volmer-Weber mode of growth. The size distributions of the platinum particles were sensitive to the heterogeneity of the substrate surface and to the competitive nucleation and growth processes

The effect of clay amendment on substrate properties and growth of woody plants

Directory of Open Access Journals (Sweden)

Tomáš Meisl

2012-01-01

Full Text Available This work deals with the effect of two clay products differing in particle size distribution on properties of growing substrate and on growth of containerized woody plants in substrates amended with these clay products. Fine and coarse clay were added to a peat substrate, each at two rates. The peat substrate without clay was used as a control. The substrates were tested in experiments with two woody ornamentals (Thuja occidentalis ’Smaragd’ and Prunus cistena. Chemical and physical properties of the substrates were measured according to European Standards before planting. Proportion of water categories differing in availability to the plants were calculated from retention curves measured on the sand box. Properties of substrates in containers with and without plants were evaluated in the same way at the end of the culture. Clay addition changed chemical and physical properties of the tested substrates in terms: available nutrients content, particle density, bulk density, total pore volume, easy available water, water buffering capacity, air capacity, and shrinkage. The effect of fine clay was much stronger. In comparison with the clear effect of clay addition on the substrate chemical and physical properties, the effect on the growth and quality of model woody plants was not so explicit.

Evaporation of Nanosuspensions on Substrates with Different Hydrophobicity.

Science.gov (United States)

Perrin, Lionel; Pajor-Swierzy, Anna; Magdassi, Shlomo; Kamyshny, Alexander; Ortega, Francisco; Rubio, Ramón G

2018-01-24

Liquid drop evaporation on surfaces is present in many industrial and medical applications, e.g., printed electronics, spraying of pesticides, DNA mapping, etc. Despite this strong interest, a theoretical description of the dynamic of the evaporation of complex liquid mixtures and nanosuspensions is still lacking. Indeed, one of the aspects that have not been included in the current theoretical descriptions is the competition between the kinetics of evaporation and the adsorption of surfactants and/or particles at the liquid/vapor and liquid/solid interfaces. Materials formed by an electrically isolating solid on which a patterned conducting layer was formed by the deposits left after drop evaporation have been considered as very promising for building electrical circuits on flexible plastic substrates. In this work, we have done an exhaustive study of the evaporation of nanosuspensions of latex and hydrophobized silver nanoparticles on four substrates of different hydrophobicity. The advancing and receding contact angles as well as the time dependence of the volume of the droplets have been measured over a broad range of particle concentrations. Also, mixtures of silver particles and a surfactant, commonly used in industrial printing, have been examined. Furthermore, the adsorption kinetics at both the air/liquid and solid/liquid interfaces have been measured. Whereas the latex particles do not adsorb at the solid/liquid and only slightly reduce the surface tension, the silver particles strongly adsorb at both interfaces. The experimental results of the evaporation process were compared with the predictions of the theory of Semenov et al. (Evaporation of Sessile Water Droplets: Universal Behavior in the Presence of Contact Angle Hysteresis. Colloids Surf. Physicochem. Eng. Asp. 2011, 391 (1-3), 135-144) and showed surprisingly good agreement despite that the theory was developed for pure liquids. The morphology of the deposits left by the droplets after total

Catalytic silica particles via template-directed molecular imprinting

Energy Technology Data Exchange (ETDEWEB)

Markowitz, M.A.; Kust, P.R.; Deng, G.; Schoen, P.E.; Dordick, J.S.; Clark, D.S.; Gaber, B.P.

2000-02-22

The surfaces of silica particle were molecularly imprinted with an {alpha}-chymotrypsin transition-state analogue (TSA) by utilizing the technique of template-directed synthesis of mineralized materials. The resulting catalytic particles hydrolyzed amides in an enantioselective manner. A mixture of a nonionic surfactant and the acylated chymotrysin TSA, with the TSA acting as the headgroup at the surfactant-water interface, was used to form a microemulsion for silica particle formation. Incorporation of amine-, dihydroimidazole-, and carboxylate-terminated trialkoxysilanes into the particles during imprinting resulted in enhancement of the rates of amide hydrolysis. Acylated imprint molecules formed more effective imprints in the presence of the functionalized silanes than nonacylated imprint molecules. Particles surface-imprinted with the chymotrypsin TSA were selective for the trypsin substrate, and particles surface-imprinted with the L-isomer of the enzyme TSA were enantioselective for the D-isomer of the substrate.

Microkeratome-assisted lamellar keratoplasty for keratoconus: stromal sandwich.

Science.gov (United States)

Bilgihan, Kamil; Ozdek, Sengül C; Sari, Ayça; Hasanreisoglu, Berati

2003-07-01

To evaluate microkeratome-assisted lamellar keratoplasty for the treatment of keratoconus when it is not possible to correct the astigmatic ametropia with contact lenses. Ophthalmology Department, School of Medicine, Gazi University, Ankara, Turkey. This prospective study comprised 9 eyes of 7 keratoconus patients with contact lens intolerance. The donor cornea was prepared with a microkeratome and punched with a 7.25 mm or 7.50 mm trephine. Following the creation of a standard 9.0 mm corneal flap in the host cornea, the donor stromal button was implanted under this corneal flap like a sandwich. Transepithelial photorefractive keratectomy or laser in situ keratomileusis was performed when the corneal topography and refraction stabilized by the end of the sixth postoperative month. Follow-up ranged from 7 to 22 months. All patients gained 5 or more lines (mean 7.2 lines +/- 1.6 [SD]), and no patient lost a line of vision. The mean corneal thickness was 432.7 +/- 36.1 micrometers preoperatively and 578.1 +/- 45.1 micrometers after refractive surgery. The early visual results of this surgical technique are promising and seem to be comparable to those with penetrating keratoplasty.

Lamellar ichthyosis maps to chromosome 14q11

Energy Technology Data Exchange (ETDEWEB)

Russell, L.J.; Compton, J.G.; Bale, S.J. [and others

1994-09-01

Lamellar ichthyosis (LI) is a serious skin disorder inherited as an autosomal recessive trait and characterized by large, brown plate-like scales covering the body. Skin involvement is apparent at birth, often as a collodion membrane. Scarring alopecia, ectropion, and secondary hypohidrosis are frequent. We used a panel of candidates genes that are expressed in the epidermis to study seven multiplex Caucasian families in the U.S. and six inbred (multiplex and simplex) families in Egypt. We find no recombination (Z=9.11 at {theta}=0) in either set of families with transglutaminse 1 (TGM1), the gene encoding the enzyme responsible for cross-linking proteins to the cell envelope in the upper-most layer of the epidermis. In addition, striking homozygosity is observed in the inbred families for markers neighboring TGM1, defining a 9.3 cM candidate region which is bounded by MYH7 and D14S275. This is the first report of linkage in LI and suggests that further study of the TGM1 gene may identify the underlying pathogenesis of this severe, disfiguring disorder. Linkage-based genetic counseling and prenatal diagnosis is now available for informative at-risk families.

Autonomous patterning of cells on microstructured fine particles

International Nuclear Information System (INIS)

Takeda, Iwori; Kawanabe, Masato; Kaneko, Arata

2015-01-01

Regularly patterned cells can clarify cellular function and are required in some biochip applications. This study examines cell patterning along microstructures and the effect of microstructural geometry on selective cellular adhesion. Particles can be autonomously assembled on a soda-lime glass substrate that is chemically patterned by immersion in a suspension of fine particles. By adopting various sizes of fine particles, we can control the geometry of the microstructure. Cells adhere more readily to microstructured fine particles than to flat glass substrate. Silica particles hexagonally packed in 5–40 μm line and space microstructures provide an effective cell scaffold on the glass substrate. Cultured cells tend to attach and proliferate along the microstructured region while avoiding the flat region. The difference in cell adhesion is attributed to their geometries, as both of the silica particles and soda-lime glass are hydrophilic related with cell adhesiveness. After cell seeding, cells adhered to the flat region migrated toward the microstructured region. For most of the cells to assemble on the scaffold, the scaffolding microstructures must be spaced by at most 65 μm. - Highlights: • PS and SiO 2 particles provide effective scaffolds for cells. • Cells that adhere to microstructured particles successfully proliferate and differentiate. • Selective adhesion and growth along the scaffold can be achieved by patterning the fine particle microstructure. • Cells adhered to flat regions migrate toward microstructured regions. • Selective adhesion by cells depends on the microstructural geometry; specifically, on the inter-line spacing

Early byzantine lamellar armour from Carthago Spartaria (Cartagena, Spain

Directory of Open Access Journals (Sweden)

Vizcaíno Sánchez, Jaime

2008-12-01

Full Text Available This article presents an Early Byzantine lamellar armour, retrieved in the excavations at the quarter built over the Roman Theatre of Cartagena. The armour has close parallels with contemporary known material from the central and eastern Mediterranean or other sites, and it is an important find which increases the body of archeological evidence about Byzantine presence in Spania.

Este artículo presenta una coraza laminar protobizantina hallada en las excavaciones del barrio construido sobre el teatro romano de Cartagena. La coraza tiene estrechos paralelos con materiales contemporáneos del Mediterráneo Central y Oriental u otros lugares, y es un importante hallazgo que incrementa la nómina de evidencias arqueológicas acerca de la presencia bizantina en Spania.

Preparation of surface enhanced Raman substrate and its characterization

Science.gov (United States)

Liu, Y.; Wang, J. Y.; Wang, J. Q.

2017-10-01

Surface enhanced Raman spectroscopy (SERS) is a fast, convenient and highly sensitive detection technique, and preparing the good effect and repeatable substrate is the key to realize the trace amount and quantitative detection in the field of food safety detection. In this paper, a surface enhanced Raman substrate based on submicrometer silver particles structure was prepared by chemical deposition method, and characterized its structure and optical properties.

Growth of tin oxide thin films composed of nanoparticles on hydrophilic and hydrophobic glass substrates by spray pyrolysis technique

Energy Technology Data Exchange (ETDEWEB)

Paloly, Abdul Rasheed; Satheesh, M. [Nano Functional Materials Lab, Department of Physics, Cochin University of Science and Technology, Kochi 682022, Kerala (India); Martínez-Tomás, M. Carmen; Muñoz-Sanjosé, Vicente [Departamento de Física Aplicada y Electromagnetismo, Universitat de Valencia, c/Dr Moliner 50, Burjassot, Valencia 46100 (Spain); Rajappan Achary, Sreekumar [Nano Functional Materials Lab, Department of Physics, Cochin University of Science and Technology, Kochi 682022, Kerala (India); Bushiri, M. Junaid, E-mail: junaidbushiri@gmail.com [Nano Functional Materials Lab, Department of Physics, Cochin University of Science and Technology, Kochi 682022, Kerala (India)

2015-12-01

Highlights: • SnO{sub 2} thin films were grown on hydrophilic and hydrophobic glass substrates. • Samples on hydrophobic substrates are having comparatively larger lattice volume. • Films on hydrophobic substrates have larger particles and low density distribution. • Substrate dependent photoluminescence emission is observed and studied. • SnO{sub 2} thin films grown over hydrophobic substrates may find potential applications. - Abstract: In this paper, we have demonstrated the growth of tin oxide (SnO{sub 2}) thin films composed of nanoparticles on hydrophobic (siliconized) and hydrophilic (non-siliconized) glass substrates by using the spray pyrolysis technique. X-ray diffraction (XRD) analysis confirmed the formation of SnO{sub 2} thin films with tetragonal rutile-phase structure. Average particle size of nanoparticles was determined to be in the range of 3–4 nm measured from the front view images obtained by a field emission gun scanning electron microscope (FESEM), while the size of nanoparticle clusters, when present, were in the range of 11–20 nm. Surface morphology of SnO{sub 2} films grown over hydrophobic substrates revealed larger isolated particles which are less crowded compared to the highly crowded and agglomerated smaller particles in films on hydrophilic substrates. Blue shift in the band gap is observed in samples in which the average particle size is slightly larger than the exciton Bohr radius. Photoluminescence (PL) analysis of samples grown over hydrophobic substrates exhibited an intense defect level emission and a weak near band edge emission. The enhanced visible emission from these SnO{sub 2} thin films is attributed to lattice defects formed during the film growth due to the mismatch between the film and the hydrophobic substrate surface.

Assessment of Geographical Variation in the Respiratory Toxicity of Desert Dust Particles

Science.gov (United States)

2013-01-01

dense nucleolus (n). There is close contact between the cells (arrowhead). The cytoplasm has many lamellar bodies – small, spherical, membrane-bound...osmiophilic, lamellar structures that contain phospholipid. Note the intact nuclear membrane (white arrow) and nucleolus (black arrow) and several

Tunable Photonic Band Gap of PS-b-P2VP Lamellar Film Using Metal Ions and pH Gradation.

Science.gov (United States)

Baek, Young-Bin; Choi, Soo-Hyung; Shin, Dong-Myung

2015-02-01

Optical properties of photonic crystal film were investigated by tuning photonic band gap (PBG). The lamellar-forming photonic films were prepared by nearly symmetric poly(styrene-b-2-vinyl pyridine) (PS-b-P2VP) block copolymers. Molecular weight of PS block and P2VP block is 52 kg/mol, and 57 kg/mol, respectively. When submerged in water, the lamellar films were swollen and show Bragg reflection in visible light region. We observed that the reflection color can be tuned by ion concentration (e.g., hydrogen or metal ion) in water. The higher concentration of hydrogen ion in solution, the longer reflectance wavelength shifted (from 537 nm to 743 nm). In addition, max-reflectance wavelength is dependent on both metal ion and the concentration. The max-reflectance wavelength is shifted from 653 nm (i.e., in water without ion) to 430 nm, 465 nm, and 505 nm for 120 mM of Ca2+, Fe2+, and Cu2+, respectively. Therefore, we can control the photonic band gap of photonic devices by changing the condition of swelling solution.

Advanced Hydraulic Studies on Enhancing Particle Removal

DEFF Research Database (Denmark)

He, Cheng

clarifier. The inlet zone of an existing rectangular storm water clarifier was redesigned to improve the fluid flow conditions and reduce the hydraulic head loss in order to remove the lamellar plates and adapt the clarifier to the needs of high-rate clarification of storm water with flocculant addition...... excessive local head losses and helped to select structural changes to reduce such losses. The analysis of the facility showed that with respect to hydraulic operation, the facility is a complex, highly non-linear hydraulic system. Within the existing constraints, a few structural changes examined......The removal of suspended solids and attached pollutants is one of the main treatment processes in wastewater treatment. This thesis presents studies on the hydraulic conditions of various particle removal facilities for possible ways to increase their treatment capacity and performance by utilizing...

CuInS[sub 2] with lamellar morphology; 2: Photoelectrochemical behavior of heterogeneous material

Energy Technology Data Exchange (ETDEWEB)

Cattarin, S. (Inst. di Polarografia ed Elettrochimica Preparativa del C.N.R., Padova (Italy)); Guerriero, P. (Inst. di Chimica e Tecnologie Inorganiche e dei Materiali Avanzati del C.N.R., Padova (Italy)); Razzini, G. (Applicata del Politecnico di Milano (Italy). Dipt. di Chimica Fisica); Lewerenz, H.J. (Hahn-Meitner-Inst., Berlin (Germany))

1994-05-01

Lamellar CuInS[sub 2] material grown in a steep temperature gradient shows heterogeneous composition and complex photoeffects. Besides predominant n-type behavior, the electrode surface has areas with intrinsic or p-type conductivity, the latter usually corresponding to indium-rich regions. An inverted (cathodic) photocurrent is observed at n-type electrodes polarized under accumulation conditions. Both spectral dependence, with a pronounced peak for energies around the bandgap, and quantum yields > 1 suggest that these photoeffects originate from photoconductivity phenomena in the crystal bulk. Variability in electronic properties limits the average performance of the material in solar cells.

Stability of the lamellar structure in Mo-TiC eutectic composite under a low vacuum at high temperatures

International Nuclear Information System (INIS)

Goto, Shoji; Nishijima, Yuzo; Yoshinaga, Hideo

1986-01-01

Thermal stability of the lamellar structure in a Mo-TiC eutectic composite has been investigated through the heat-treatment at 1523 - 2223 K for 5.76 x 10 4 - 3.6 x 10 5 s under a low vacuum pressure of 13 mPa. It was found that the TiC phase in the eutectic lamellar disappeared above the critical temperature of about 1750 K, but below the critical temperature the disappearance of TiC phase was hardly observed and TiO film was formed on the surface. The Mo matrix phase was not oxidized and was stable at all test temperatures, since its affinity for oxygen is lower than that for carbon and titanium. It is presumed that at higer temperatures the disappearance process of TiC phase is controlled by the diffusion of carbon atoms through the matrix to the surface, and carbon and titanium atoms on the surface are removed by CO gas formation and TiO evaporation, respectively, but at lower temperatures the evaporation of TiO is so slow that the TiO film is formed on the surface. (author)

Directed Magnetic Particle Transport above Artificial Magnetic Domains Due to Dynamic Magnetic Potential Energy Landscape Transformation.

Science.gov (United States)

Holzinger, Dennis; Koch, Iris; Burgard, Stefan; Ehresmann, Arno

2015-07-28

An approach for a remotely controllable transport of magnetic micro- and/or nanoparticles above a topographically flat exchange-bias (EB) thin film system, magnetically patterned into parallel stripe domains, is presented where the particle manipulation is achieved by sub-mT external magnetic field pulses. Superparamagnetic core-shell particles are moved stepwise by the dynamic transformation of the particles' magnetic potential energy landscape due to the external magnetic field pulses without affecting the magnetic state of the thin film system. The magnetic particle velocity is adjustable in the range of 1-100 μm/s by the design of the substrate's magnetic field landscape (MFL), the particle-substrate distance, and the magnitude of the applied external magnetic field pulses. The agglomeration of magnetic particles is avoided by the intrinsic magnetostatic repulsion of particles due to the parallel alignment of the particles' magnetic moments perpendicular to the transport direction and parallel to the surface normal of the substrate during the particle motion. The transport mechanism is modeled by a quantitative theory based on the precise knowledge of the sample's MFL and the particle-substrate distance.

Simultaneous topography-guided PRK followed by corneal collagen cross-linking after lamellar keratoplasty for keratoconus.

Science.gov (United States)

Spadea, Leopoldo; Paroli, Marino

2012-01-01

The purpose of this paper is to report the results of using combined treatment of customized excimer laser-assisted photorefractive keratectomy (PRK) and prophylactic corneal collagen crosslinking (CXL) for residual refractive error in a group of patients who had previously undergone lamellar keratoplasty for keratoconus. The study included 14 eyes from 14 patients who had originally been treated for keratoconus in one eye by excimer laser-assisted lamellar keratoplasty (ELLK), and subsequently presented with residual ametropia (-6.11 D ± 2.48, range -2.50 to -9.50). After a mean 40.1 ± 12.4 months since ELLK they underwent combined simultaneous corneal regularization treatment with topographically guided transepithelial excimer laser PRK (central corneal regularization) and corneal CXL induced by riboflavin-ultraviolet A. After a mean 15 ± 6.5 (range 6-24) months, all eyes gained at least one Snellen line of uncorrected distance visual acuity (range 1-10). No patient lost lines of corrected distance visual acuity, and four patients gained three lines of corrected distance visual acuity. Mean manifest refractive spherical equivalent was -0.79 ± 2.09 (range +1 to -3.0) D, and topographic keratometric astigmatism was 5.02 ± 2.93 (range 0.8-8.9) D. All the corneas remained clear (haze PRK and corneal CXL provided safe and effective results in the management of corneal regularization for refractive purposes after ELLK for keratoconus.

In-situ TEM investigations of graphic-epitaxy and small particles

Science.gov (United States)

Heinemann, K.

1983-01-01

Palladium was deposited inside a controlled-vacuum specimen chamber of a transmission electron microscope (TEM) onto MgO and alpha-alumina substrate surfaces. Annealing and various effects of gas exposure of the particulate Pd deposits were studied in-situ by high resolution TEM and electron diffraction. Whereas substrate temperatures of 500 C or annealing of room temperature (RT) deposits to 500 C were needed to obtain epitaxy on sapphire, RT deposits on MgO were perfectly epitaxial. For Pd/MgO a lattice expansion of 2 to 4% was noted; the highest values of expansion were found for the smallest particles. The lattice expansion of small Pd particles on alumina substrates was less than 1%. Long-time RT exposure of Pd/MgO in a vacuum yielded some moblity and coalescence events, but notably fewer than for Pd on sapphire. Exposure to air or oxygen greatly enhanced the particle mobility and coalescence and also resulted in the flattening of Pd particles on MgO substrates. Electron-beam irradiation further enhanced this effect. Exposure to air for several tens of hours of Pd/MgO led to strong coalescence.

Probing ADAMTS13 substrate specificity using phage display.

Directory of Open Access Journals (Sweden)

Karl C Desch

Full Text Available Von Willebrand factor (VWF is a large, multimeric protein that regulates hemostasis by tethering platelets to the subendothelial matrix at sites of vascular damage. The procoagulant activity of plasma VWF correlates with the length of VWF multimers, which is proteolytically controlled by the metalloprotease ADAMTS13. To probe ADAMTS13 substrate specificity, we created phage display libraries containing randomly mutated residues of a minimal ADAMTS13 substrate fragment of VWF, termed VWF73. The libraries were screened for phage particles displaying VWF73 mutant peptides that were resistant to proteolysis by ADAMTS13. These peptides exhibited the greatest mutation frequency near the ADAMTS13 scissile residues. Kinetic assays using mutant and wild-type substrates demonstrated excellent agreement between rates of cleavage for mutant phage particles and the corresponding mutant peptides. Cleavage resistance of selected mutations was tested in vivo using hydrodynamic injection of corresponding full-length expression plasmids into VWF-deficient mice. These studies confirmed the resistance to cleavage resulting from select amino acid substitutions and uncovered evidence of alternate cleavage sites and recognition by other proteases in the circulation of ADAMTS13 deficient mice. Taken together, these studies demonstrate the key role of specific amino acids residues including P3-P2' and P11', for substrate specificity and emphasize the importance in flowing blood of other ADAMTS13-VWF exosite interactions outside of VWF73.

Structure of lamellar lipid domains and corneocyte envelopes of murine stratum corneum. An X-ray diffraction study

International Nuclear Information System (INIS)

White, S.H.; Mirejovsky, D.; King, G.I.

1988-01-01

The lipid of the outermost layer of the skin is confined largely to the extracellular spaces surrounding the corneocytes of the stratum corneum where it forms a multilamellar adhesive matrix to act as the major permeability barrier of the skin. Knowledge of the molecular architecture of these intercellular domains is important for understanding various skin pathologies and their treatment, percutaneous drug delivery, and the cosmetic maintenance of the skin. The authors have surveyed by X-ray diffraction the structure of the intercellular domains and the extracted lipids of murine stratum corneum (SC) at 25, 45, and 70 0 C which are temperatures in the vicinity of known thermal phase transitions. The intercellular domains produce lamellar diffraction patterns with a Bragg spacing of 131 +/- 2 A. Lipid extracted from the SC and dispersed in excess water does not produce a simple lamellar diffraction pattern at any temperature studied, however. This and other facts suggest that another component, probably a protein, must be present to control the architecture of the intercellular lipid domains. They have also obtained diffraction patterns attributable to the protein envelopes of the corneocytes. The patterns suggest a β-pleated sheet organizational scheme. No diffraction patterns were observed that could be attributed to keratin

Fumonisin B₁ (FB₁) Induces Lamellar Separation and Alters Sphingolipid Metabolism of In Vitro Cultured Hoof Explants.

Science.gov (United States)

Reisinger, Nicole; Dohnal, Ilse; Nagl, Veronika; Schaumberger, Simone; Schatzmayr, Gerd; Mayer, Elisabeth

2016-03-24

One of the most important hoof diseases is laminitis. Yet, the pathology of laminitis is not fully understood. Different bacterial toxins, e.g. endotoxins or exotoxins, seem to play an important role. Additionally, ingestion of mycotoxins, toxic secondary metabolites of fungi, might contribute to the onset of laminitis. In this respect, fumonsins are of special interest since horses are regarded as species most susceptible to this group of mycotoxins. The aim of our study was to investigate the influence of fumonisin B₁ (FB₁) on primary isolated epidermal and dermal hoof cells, as well as on the lamellar tissue integrity and sphingolipid metabolism of hoof explants in vitro. There was no effect of FB₁ at any concentration on dermal or epidermal cells. However, FB₁ significantly reduced the separation force of explants after 24 h of incubation. The Sa/So ratio was significantly increased in supernatants of explants incubated with FB₁ (2.5-10 µg/mL) after 24 h. Observed effects on Sa/So ratio were linked to significantly increased sphinganine concentrations. Our study showed that FB₁ impairs the sphingolipid metabolism of explants and reduces lamellar integrity at non-cytotoxic concentrations. FB₁ might, therefore, affect hoof health. Further in vitro and in vivo studies are necessary to elucidate the effects of FB₁ on the equine hoof in more detail.

Substrate milling pretreatment as a key parameter for Solid-State Anaerobic Digestion optimization.

Science.gov (United States)

Motte, J-C; Escudié, R; Hamelin, J; Steyer, J-P; Bernet, N; Delgenes, J-P; Dumas, C

2014-12-01

The effect of milling pretreatment on performances of Solid-State Anaerobic Digestion (SS-AD) of raw lignocellulosic residue is still controverted. Three batch reactors treating different straw particle sizes (milled 0.25 mm, 1 mm and 10 mm) were followed during 62 days (6 sampling dates). Although a fine milling improves substrate accessibility and conversion rate (up to 30% compared to coarse milling), it also increases the risk of media acidification because of rapid and high acids production during fermentation of the substrate soluble fraction. Meanwhile, a gradual adaptation of microbial communities, were observed according to both reaction progress and methanogenic performances. The study concluded that particle size reduction affected strongly the performances of the reaction due to an increase of substrate bioaccessibility. An optimization of SS-AD processes thanks to particle size reduction could therefore be applied at farm or industrial scale only if a specific management of the soluble compounds is established. Copyright © 2014 Elsevier Ltd. All rights reserved.

Stress relaxation experiments on a lamellar polystyrene-polyisoprene diblock copolymer melt

DEFF Research Database (Denmark)

Holmqvist, P.; Castelletto, V.; Hamley, I.W.

2001-01-01

The non-linear rheology of the lamellar phase of a polystyrene-polyisoprene diblock copolymer is studied by oscillatory shear experiments. The relaxation of the shear modulus, G(t, gamma) is studied as a function of strain amplitude, gamma, up to large amplitude strains, gamma = 100%. The decay...... of G(t, gamma) is analysed using the model-independent CONTIN inverse Laplace transform algorithm to obtain a series of relaxation times, which reveals multiple relaxation processes. The timescale for the fastest relaxation processes is compared to those previously observed for diblock copolymer melts...... via dynamic light scattering experiments. The slowest relaxation process may be related to the shear-induced orientation of the lamellae. It is shown that time-strain separability G(t, gamma)= G(t)h(gamma) can be applied, and the damping function h(gamma) is consistent with a strongly strain...

Deposition of bi-dispersed particles in inkjet-printed evaporating colloidal drops

Science.gov (United States)

Sun, Ying; Joshi, Abhijit; Chhasatia, Viral

2010-11-01

In this study, the deposition behaviors of inkjet-printed evaporating colloidal drops consisting of bi-dispersed micro and nano-sized particles are investigated by fluorescence microscopy and SEM. The results on hydrophilic glass substrates show that, evaporatively-driven outward flow drives the nanoparticles to deposit close to the pinned contact line while an inner ring deposition is formed by microparticles. This size-induced particle separation is consistent with the existence of a wedge-shaped drop edge near the contact line region of an evaporating drop on a hydrophilic substrate. The replenishing evaporatively-driven flow assembles nanoparticles closer to the pinned contact line forming an outer ring of nanoparticles and this particle jamming further enhances the contact line pinning. Microparticles are observed to form an inner ring inside the nano-sized deposits. This size-induced particle separation presents a new challenge to the uniformity of functional materials in bioprinting applications where nanoparticles and micro-sized cells are mixed together. On the other hand, particle self-assembly based on their sizes provides enables easy and well-controlled pattern formation. The effects of particle size contrast, particle volume fraction, substrate surface energy, and relative humidity of the printing environment on particle separation are examined in detail.

Measurement of Anisotropic Particle Interactions with Nonuniform ac Electric Fields.

Science.gov (United States)

Rupp, Bradley; Torres-Díaz, Isaac; Hua, Xiaoqing; Bevan, Michael A

2018-02-20

Optical microscopy measurements are reported for single anisotropic polymer particles interacting with nonuniform ac electric fields. The present study is limited to conditions where gravity confines particles with their long axis parallel to the substrate such that particles can be treated using quasi-2D analysis. Field parameters are investigated that result in particles residing at either electric field maxima or minima and with long axes oriented either parallel or perpendicular to the electric field direction. By nonintrusively observing thermally sampled positions and orientations at different field frequencies and amplitudes, a Boltzmann inversion of the time-averaged probability of states yields kT-scale energy landscapes (including dipole-field, particle-substrate, and gravitational potentials). The measured energy landscapes show agreement with theoretical potentials using particle conductivity as the sole adjustable material property. Understanding anisotropic particle-field energy landscapes vs field parameters enables quantitative control of local forces and torques on single anisotropic particles to manipulate their position and orientation within nonuniform fields.

Ion transport mechanisms in lamellar phases of salt-doped PS–PEO block copolymer electrolytes

KAUST Repository

Sethuraman, Vaidyanathan; Mogurampelly, Santosh; Ganesan, Venkat

2017-01-01

We use a multiscale simulation strategy to elucidate, at an atomistic level, the mechanisms underlying ion transport in the lamellar phase of polystyrene–polyethylene oxide (PS–PEO) block copolymer (BCP) electrolytes doped with LiPF6 salts. Explicitly, we compare the results obtained for ion transport in the microphase separated block copolymer melts to those for salt-doped PEO homopolymer melts. In addition, we also present results for dynamics of the ions individually in the PEO and PS domains of the BCP melt, and locally as a function of the distance from the lamellar interfaces. When compared to the PEO homopolymer melt, ions were found to exhibit slower dynamics in both the block copolymer (overall) and in the PEO phase of the BCP melt. Such results are shown to arise from the effects of slower polymer segmental dynamics in the BCP melt and the coordination characteristics of the ions. Polymer backbone-ion residence times analyzed as a function of distance from the interface indicate that ions have a larger residence time near the interface compared to that near the bulk of lamella, and demonstrates the influence of the glassy PS blocks and microphase segregation on the ion transport properties. Ion transport mechanisms in BCP melts reveal that there exist five distinct mechanisms for ion transport along the backbone of the chain and exhibit qualitative differences from the behavior in homopolymer melts. We also present results as a function of salt concentration which show that the mean-squared displacements of the ions decrease with increasing salt concentration, and that the ion residence times near the polymer backbone increase with increasing salt concentration.

Ion transport mechanisms in lamellar phases of salt-doped PS–PEO block copolymer electrolytes

KAUST Repository

Sethuraman, Vaidyanathan

2017-10-23

We use a multiscale simulation strategy to elucidate, at an atomistic level, the mechanisms underlying ion transport in the lamellar phase of polystyrene–polyethylene oxide (PS–PEO) block copolymer (BCP) electrolytes doped with LiPF6 salts. Explicitly, we compare the results obtained for ion transport in the microphase separated block copolymer melts to those for salt-doped PEO homopolymer melts. In addition, we also present results for dynamics of the ions individually in the PEO and PS domains of the BCP melt, and locally as a function of the distance from the lamellar interfaces. When compared to the PEO homopolymer melt, ions were found to exhibit slower dynamics in both the block copolymer (overall) and in the PEO phase of the BCP melt. Such results are shown to arise from the effects of slower polymer segmental dynamics in the BCP melt and the coordination characteristics of the ions. Polymer backbone-ion residence times analyzed as a function of distance from the interface indicate that ions have a larger residence time near the interface compared to that near the bulk of lamella, and demonstrates the influence of the glassy PS blocks and microphase segregation on the ion transport properties. Ion transport mechanisms in BCP melts reveal that there exist five distinct mechanisms for ion transport along the backbone of the chain and exhibit qualitative differences from the behavior in homopolymer melts. We also present results as a function of salt concentration which show that the mean-squared displacements of the ions decrease with increasing salt concentration, and that the ion residence times near the polymer backbone increase with increasing salt concentration.

Amino acid transport system - A substrate predicts the therapeutic effects of particle radiotherapy.

Directory of Open Access Journals (Sweden)

Tomoya Uehara

Full Text Available L-[methyl-11C]Methionine (11C-Met is useful for estimating the therapeutic efficacy of particle radiotherapy at early stages of the treatment. Given the short half-life of 11C, the development of longer-lived 18F- and 123I-labeled probes that afford diagnostic information similar to 11C-Met, are being sought. Tumor uptake of 11C-Met is involved in many cellular functions such as amino acid transport System-L, protein synthesis, and transmethylation. Among these processes, since the energy-dependent intracellular functions involved with 11C-Met are more reflective of the radiotherapeutic effects, we evaluated the activity of the amino acid transport System-A as an another energy-dependent cellular function in order to estimate radiotherapeutic effects. In this study, using a carbon-ion beam as the radiation source, the activity of System-A was evaluated by a specific System-A substrate, alpha-[1-14C]-methyl-aminoisobutyric acid (14C-MeAIB. Cellular growth and the accumulation of 14C-MeAIB or 14C-Met were evaluated over time in vitro in cultured human salivary gland (HSG tumor cells (3-Gy or in vivo in murine xenografts of HSG tumors (6- or 25-Gy before and after irradiation with the carbon-ion beam. Post 3-Gy irradiation, in vitro accumulation of 14C-Met and 14C-MeAIB decreased over a 5-day period. In xenografts of HSG tumors in mice, tumor re-growth was observed in vivo on day-10 after a 6-Gy irradiation dose, but no re-growth was detected after the 25-Gy irradiation dose. Consistent with the growth results, the in vivo tumor accumulation of 14C-MeAIB did not decrease after the 6-Gy irradiation dose, whereas a significant decrease was observed after the 25-Gy irradiation dose. These results indicate that the activity of energy dependent System-A transporter may reflect the therapeutic efficacy of carbon-ion radiotherapy and suggests that longer half-life radionuclide-labeled probes for System-A may also provide widely available probes to

Probing ADAMTS13 Substrate Specificity using Phage Display

Science.gov (United States)

Desch, Karl C.; Kretz, Colin; Yee, Andrew; Gildersleeve, Robert; Metzger, Kristin; Agrawal, Nidhi; Cheng, Jane; Ginsburg, David

2015-01-01

Von Willebrand factor (VWF) is a large, multimeric protein that regulates hemostasis by tethering platelets to the subendothelial matrix at sites of vascular damage. The procoagulant activity of plasma VWF correlates with the length of VWF multimers, which is proteolytically controlled by the metalloprotease ADAMTS13. To probe ADAMTS13 substrate specificity, we created phage display libraries containing randomly mutated residues of a minimal ADAMTS13 substrate fragment of VWF, termed VWF73. The libraries were screened for phage particles displaying VWF73 mutant peptides that were resistant to proteolysis by ADAMTS13. These peptides exhibited the greatest mutation frequency near the ADAMTS13 scissile residues. Kinetic assays using mutant and wild-type substrates demonstrated excellent agreement between rates of cleavage for mutant phage particles and the corresponding mutant peptides. Cleavage resistance of selected mutations was tested in vivo using hydrodynamic injection of corresponding full-length expression plasmids into VWF-deficient mice. These studies confirmed the resistance to cleavage resulting from select amino acid substitutions and uncovered evidence of alternate cleavage sites and recognition by other proteases in the circulation of ADAMTS13 deficient mice. Taken together, these studies demonstrate the key role of specific amino acids residues including P3-P2’ and P11’, for substrate specificity and emphasize the importance in flowing blood of other ADAMTS13–VWF exosite interactions outside of VWF73. PMID:25849793

Diffuse lamellar keratitis after laser in situ keratomileusis with the Moria LSK-One and Carriazo-Barraquer microkeratomes.

Science.gov (United States)

Thammano, Pavika; Rana, Azhar N; Talamo, Jonathan H

2003-10-01

To assess risk factors for and incidence of diffuse lamellar keratitis (DLK) and to investigate whether microkeratome design is associated with the incidence of DLK. The Laser Eye Consultants of Boston, Boston and Waltham, Massachusetts, USA. In a retrospective nonrandomized comparative study, 1122 consecutive primary laser in situ keratomileusis (LASIK) treatments (584 patients) were analyzed to determine the incidence of DLK using 2 different microkeratome designs (Moria LSK-One [LSK] and Moria Carriazo-Barraquer [C-B]). The incidence of DLK was as determined by clinical signs. The overall incidence of DLK was 2.23%. The incidence in the LSK and C-B groups was 1.09% and 4.38%, respectively, with a statistically significant difference in incidence between the 2 groups (P<.01). Epithelial irregularities increased the risk for DLK. There was no significant statistical difference in sex, age, operating room location, type of laser, or time of day the surgery was performed between the 2 groups or between eyes that had DLK and eyes without DLK. The incidence of DLK using the C-B microkeratome fell significantly after May 2000, when new cleaning methods for this device were introduced. Different microkeratomes and how they are maintained may influence the incidence of DLK. Diffuse lamellar keratitis is more common after LASIK in a setting of epithelial irregularities, whether or not an actual epithelial defect is created.

Numerical simulation of white double-layer coating with different submicron particles on the spectral reflectance

International Nuclear Information System (INIS)

Chai, Jiale; Cheng, Qiang; Si, Mengting; Su, Yang; Zhou, Yifan; Song, Jinlin

2017-01-01

The spectral selective coating is becoming more and more popular against solar irradiation not only in keeping the coated objects stay cool but also retain the appearance of the objects by reducing the glare of reflected sunlight. In this work a numerical study is investigated to design the double-layer coating with different submicron particles to achieve better performance both in thermal and aesthetic aspects. By comparison, the performance of double-layer coating with TiO_2 and ZnO particles is better than that with single particles. What's more, the particle diameter, volume fraction of particle as well as substrate condition is also investigated. The results show that an optimized double-layer coating with particles should be the one with an appropriate particle diameter, volume fraction and the black substrate. - Highlights: • The double-layer coating has a great influence on both thermal and aesthetic aspects. • The double-layer coating performs better than the uniform one with single particles. • The volume fraction, particle diameter and substrate conditions are optimized.

Alpha spectrometric characterization of process-related particle size distributions from active particle sampling at the Los Alamos National Laboratory uranium foundry

Energy Technology Data Exchange (ETDEWEB)

Plionis, Alexander A [Los Alamos National Laboratory; Peterson, Dominic S [Los Alamos National Laboratory; Tandon, Lav [Los Alamos National Laboratory; Lamont, Stephen P [Los Alamos National Laboratory

2009-01-01

Uranium particles within the respirable size range pose a significant hazard to the health and safety of workers. Significant differences in the deposition and incorporation patterns of aerosols within the respirable range can be identified and integrated into sophisticated health physics models. Data characterizing the uranium particle size distribution resulting from specific foundry-related processes are needed. Using personal air sampling cascade impactors, particles collected from several foundry processes were sorted by activity median aerodynamic diameter onto various Marple substrates. After an initial gravimetric assessment of each impactor stage, the substrates were analyzed by alpha spectrometry to determine the uranium content of each stage. Alpha spectrometry provides rapid nondestructive isotopic data that can distinguish process uranium from natural sources and the degree of uranium contribution to the total accumulated particle load. In addition, the particle size bins utilized by the impactors provide adequate resolution to determine if a process particle size distribution is: lognormal, bimodal, or trimodal. Data on process uranium particle size values and distributions facilitate the development of more sophisticated and accurate models for internal dosimetry, resulting in an improved understanding of foundry worker health and safety.

Formation of lamellar cross bridges in the annulus fibrosus of the intervertebral disc is a consequence of vascular regression.

Science.gov (United States)

Smith, Lachlan J; Elliott, Dawn M

2011-05-01

Cross bridges are radial structures within the highly organized lamellar structure of the annulus fibrosus of the intervertebral disc that connect two or more non-consecutive lamellae. Their origin and function are unknown. During fetal development, blood vessels penetrate deep within the AF and recede during postnatal growth. We hypothesized that cross bridges are the pathways left by these receding blood vessels. Initially, the presence of cross bridges was confirmed in cadaveric human discs aged 25 and 53 years. Next, L1-L2 intervertebral discs (n=4) from sheep ranging in age from 75 days fetal gestation to adult were processed for paraffin histology. Mid-sagittal sections were immunostained for endothelial cell marker PECAM-1. The anterior and posterior AF were imaged using differential interference contrast microscopy, and the following parameters were quantified: total number of distinct lamellae, total number of cross bridges, percentage of cross bridges staining positive for PECAM-1, cross bridge penetration depth (% total lamellae), and PECAM-1 positive cross bridge penetration depth. Cross bridges were first observed at 100 days fetal gestation. The overall number peaked in neonates then remained relatively unchanged. The percentage of PECAM-1 positive cross bridges declined progressively from almost 100% at 100 days gestation to less than 10% in adults. Cross bridge penetration depth peaked in neonates then remained unchanged at subsequent ages. Depth of PECAM-1 positive cross bridges decreased progressively after birth. Findings were similar for both the anterior and posterior. The AF lamellar architecture is established early in development. It later becomes disrupted as a consequence of vascularization. Blood vessels then recede, perhaps due to increasing mechanical stresses in the surrounding matrix. In this study we present evidence that the pathways left by receding blood vessels remain as lamellar cross bridges. It is unclear whether the presence

Microstructural characterisation of Ni75Al25 and Ni31.5Al68.5 powder particles produced by gas atomisation

International Nuclear Information System (INIS)

García-Escorial, A.; Lieblich, M.

2014-01-01

Highlight: ► Successful production of gas atomised Ni75Al25 and Ni31.5Al68.5 powder particles. ► Characterization of the as-solidified microstructure of 75 Al 25 and Ni 31.5 Al 68.5 at.% powder particles below 100 μm in size have been studied. The gas atomised Ni 75 Al 25 powder particles are mainly spherical. The solidification of this alloy is very fast, and its microstructure consists of a dendrite and lamellar structure of partially ordered γ-(Ni), γ′-Ni 3 Al L1 2 phase, and β-NiAl phase. The order increases with the powder particle size. The gas atomised Ni 31.5 Al 68.5 powder particles are also spherical in shape. The microstructure consists of Ni 2 Al 3 dendrites with interdendritic peritectic NiAl 3 and eutectic NiAl 3 + α-Al. The amount of the Ni 2 Al 3 increases as the cooling rate increases. NiAl phase is absent in the gas atomised Ni 31.5 Al 68.5 powder

Temporal succession in carbon incorporation from macromolecules by particle-attached bacteria in marine microcosms: Particle-attached bacteria incorporating organic carbon

Energy Technology Data Exchange (ETDEWEB)

Mayali, Xavier [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Stewart, Benjamin [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Mabery, Shalini [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Weber, Peter K. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)

2015-12-21

Here, we investigated bacterial carbon assimilation from stable isotope-labelled macromolecular substrates (proteins; lipids; and two types of polysaccharides, starch and cellobiose) while attached to killed diatom detrital particles during laboratory microcosms incubated for 17 days. Using Chip-SIP (secondary ion mass spectrometry analysis of RNA microarrays), we identified generalist operational taxonomic units (OTUs) from the Gammaproteobacteria, belonging to the genera Colwellia, Glaciecola, Pseudoalteromonas and Rheinheimera, and from the Bacteroidetes, genera Owenweeksia and Maribacter, that incorporated the four tested substrates throughout the incubation period. Many of these OTUs exhibited the highest isotope incorporation relative to the others, indicating that they were likely the most active. Additional OTUs from the Gammaproteobacteria, Bacteroidetes and Alphaproteobacteria exhibited generally (but not always) lower activity and did not incorporate all tested substrates at all times, showing species succession in organic carbon incorporation. We also found evidence to suggest that both generalist and specialist OTUs changed their relative substrate incorporation over time, presumably in response to changing substrate availability as the particles aged. This pattern was demonstrated by temporal succession from relatively higher starch incorporation early in the incubations, eventually switching to higher cellobiose incorporation after 2 weeks.

The application of Lorentz transmission electron microscopy to the study of lamellar magnetism in hematite-ilmenite

DEFF Research Database (Denmark)

Kasama, Takeshi; Dunin-Borkowski, Rafal E.; Asaka, T

2009-01-01

. However, the magnitude of the experimental contrast is higher than that in the simulations, suggesting that an alternative origin for the observed asymmetry cannot be ruled out. Electron tomography was used to show that the lamellae have lens-like shapes and that (001) planes make up a significant...... in hematite. The likelihood that lamellar magnetism may be responsible for this contrast is assessed using simulations that incorporate interfacial magnetic moments on the (001) basal planes of hematite and ilmenite. The simulations suggest qualitatively that the asymmetric contrast is magnetic in origin...

TiO2 thin-films on polymer substrates and their photocatalytic activity

International Nuclear Information System (INIS)

Yang, Jae-Hun; Han, Yang-Su; Choy, Jin-Ho

2006-01-01

We have developed dip-coating process for TiO 2 -thin film on polymer substrates (acrylonitrile-butadiene-styrene polymer: ABS, polystyrene: PS). At first, a monodispersed and transparent TiO 2 nano-sol solution was prepared by the controlled hydrolysis of titanium iso-propoxide in the presence of acetylacetone and nitric acid catalyst at 80 deg. C. Powder X-ray diffraction patterns of the dried particles are indicative of crystalline TiO 2 with anatase-type structure. According to the XRD and transmission electron microscopy (TEM) studies, the mean particle size was estimated to be ca. 5 nm. The transparent thin films on ABS and PS substrates were fabricated by dip-coating process by changing the processing variables, such as the number of dip-coating and TiO 2 concentration in nano-sol solution. Scanning electron microscopic (SEM) analysis for the thin film samples reveals that the acetylacetone-modified TiO 2 nano-sol particles are effective for enhancing the interfacial adherence between films and polymeric substrates compared to the unmodified one. Photocatalytic degradation of methylene blue (MB) on the TiO 2 thin-films has also been systematically investigated

Electrodeposition of nickel particles and their characterization

Energy Technology Data Exchange (ETDEWEB)

Martinez, G. T. [Centro de Investigacion en Quimica Aplicada, Laboratorio de Microscopia. Blvd. Enrique Reyna No. 140, Saltillo 25253, Coahuila (Mexico); Zavala, G.; Videa, M. [ITESM, Campus Monterrey, Depto. de Fisica, Av. Garza Sada 2501 Sur, Monterrey 64849, N. L. (Mexico)], e-mail: gtadeo@ciqa.mx

2009-07-01

Electrodeposition of nickel particles on ITO substrates is achieved by current pulse reduction. A comparison between potential pulse and current pulse experiments presents differences in particle size and particle size distribution. The latter shows smaller particle size dispersion than what is found with potential pulses. Characterization of the particles carried out by Atomic Force Microscopy shows particles with average sizes between 100 to 300 nm. Magnetic characterization by Magnetic Force Microscopy and SQUID shows that particles of {approx} 300 nm were ferromagnetic with a coercive field of 200 Oe and a saturation magnetization of 40 x 10{sup -6} emu at 300 K. (Author)

Particle detection with superconducting tunnel junctions

International Nuclear Information System (INIS)

Jany, P.

1990-08-01

At the Institute of Experimental Nuclear Physics of the University of Karlsruhe (TH) and at the Institute for Nuclear Physics of the Kernforschungszentrum Karlsruhe we started to produce superconducting tunnel junctions and to investigate them for their suitability as particle detectors. The required facilities for the production of tunnel junctions and the experimental equipments to carry out experiments with them were erected. Experiments are presented in which radiations of different kinds of particles could successfully be measured with the tunnel junctions produced. At first we succeeded in detectioning light pulses of a laser. In experiments with alpha-particles of an energy of 4,6 MeV the alpha-particles were detected with an energy resolution of 1,1%, and it was shown in specific experiments that the phonons originating from the deposition of energy by an alpha-particle in the substrate can be detected with superconducting tunnel junctions at the surface. On that occasion it turned out that the signals could be separated with respect to their point of origin (tunnel junction, contact leads, substrate). Finally X-rays with an energy of 6 keV were detected with an energy resolution of 8% in a test arrangement that makes use of the so-called trapping effect to read out a larger absorber volume. (orig.) [de

Analysis and prediction of stacking sequences in intercalated lamellar vanadium phosphates

Energy Technology Data Exchange (ETDEWEB)

Gautier, Romain [Institut des Sciences Chimiques de Rennes, UMR 6226 CNRS - Ecole Nationale Superieure de Chimie de Rennes (France); Centre Nationale de la Recherche Scientifique (CNRS), Institut des Materiaux Jean Rouxel (IMN), Universite de Nantes (France); Fourre, Yoann; Furet, Eric; Gautier, Regis; Le Fur, Eric [Institut des Sciences Chimiques de Rennes, UMR 6226 CNRS - Ecole Nationale Superieure de Chimie de Rennes (France)

2015-04-15

An approach is presented that enables the analysis and prediction of stacking sequences in intercalated lamellar vanadium phosphates. A comparison of previously reported vanadium phosphates reveals two modes of intercalation: (i) 3d transition metal ions intercalated between VOPO{sub 4} layers and (ii) alkali/alkaline earth metal ions between VOPO{sub 4}.H{sub 2}O layers. Both intercalations were investigated using DFT calculations in order to understand the relative shifts of the vanadium phosphate layers. These calculations in addition to an analysis of the stacking sequences in previously reported materials enable the prediction of the crystal structures of M{sub x}(VOPO{sub 4}).yH{sub 2}O (M = Cs{sup +}, Cd{sup 2+} and Sn{sup 2+}). Experimental realization and structural determination of Cd(VOPO{sub 4}){sub 2}.4H{sub 2}O by single-crystal X-ray diffraction confirmed the predicted stacking sequences. (Copyright copyright 2015 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

Boron nitride nanosheets as improved and reusable substrates for gold nanoparticles enabled surface enhanced Raman spectroscopy

KAUST Repository

Cai, Qiran

2015-01-01

Atomically thin boron nitride (BN) nanosheets have been found to be excellent substrates for noble metal particles enabled surface enhanced Raman spectroscopy (SERS), thanks to their good adsorption of aromatic molecules, high thermal stability and weak Raman scattering. Faceted gold (Au) nanoparticles have been synthesized on BN nanosheets using a simple but controllable and reproducible sputtering and annealing method. The size and density of the Au particles can be controlled by sputtering time, current and annealing temperature etc. Under the same sputtering and annealing conditions, the Au particles on BN of different thicknesses show various sizes because the surface diffusion coefficients of Au depend on the thickness of BN. Intriguingly, decorated with similar morphology and distribution of Au particles, BN nanosheets exhibit better Raman enhancements than silicon substrates as well as bulk BN crystals. Additionally, BN nanosheets show no noticeable SERS signal and hence cause no interference to the Raman signal of the analyte. The Au/BN substrates can be reused by heating in air to remove the adsorbed analyte without loss of SERS enhancement. This journal is © the Owner Societies 2015.

Influence of the particle morphology on the Cold Gas Spray deposition behaviour of titanium on aluminum light alloys

International Nuclear Information System (INIS)

Cinca, N.; Rebled, J.M.; Estradé, S.; Peiró, F.; Fernández, J.; Guilemany, J.M.

2013-01-01

Highlights: ► Study of the particle–substrate and particle–particle interfaces in the cold spray process. ► Use of irregular feedstock particles whereas normally FIB studies have been undergone for spherical particles. ► Deep Transmission Electron Microscopy characterization of the interfaces and within the particle. -- Abstract: The present work evaluates the deposition behaviour of irregular titanium powder particles impinged by Cold Gas Spraying onto an aluminium 7075-T6 alloy substrate. The influence of their irregular shape on the bonding phenomena, in particle–substrate and particle–particle interfaces are discussed in view of Transmission Electron Microscopy examinations of a Focused Ion Beam lift-out prepared sample. Key aspects will be the jetting-out, the occurrence of oxide layers and grain size refinement. Different structural morphologies could be featured; at the particle–substrate interface, both the aluminium alloy and the titanium side exhibit recrystallization. Titanium particles in intimate contact in small agglomerates during deposition, on the other hand, show grain refinement at their interfaces whereas the original structure is maintained outside those boundaries

Biochemical transformation of calciprotein particles in uraemia.

Science.gov (United States)

Smith, Edward R; Hewitson, Tim D; Hanssen, Eric; Holt, Stephen G

2018-05-01

Calciprotein particles (CPP) have emerged as nanoscale mediators of phosphate-induced toxicity in Chronic Kidney Disease (CKD). Uraemia favors ripening of the particle mineral content from the amorphous (CPP-I) to the crystalline state (CPP-II) but the pathophysiological significance of this transformation is uncertain. Clinical studies suggest an association between CPP ripening and inflammation, vascular dysfunction and mortality. Although ripening has been modelled in vitro, it is unknown whether particles synthesised in serum resemble their in vivo counterparts. Here we show that in vitro formation and ripening of CPP in uraemic serum is characterised by extensive physiochemical rearrangements involving the accretion of mineral, loss of surface charge and transformation of the mineral phase from a spherical arrangement of diffuse domains of amorphous calcium phosphate to densely-packed lamellar aggregates of crystalline hydroxyapatite. These physiochemical changes were paralleled by enrichment with small soluble apolipoproteins, complement factors and the binding of fatty acids. In comparison, endogenous CPP represent a highly heterogeneous mixture of particles with characteristics mostly intermediate to synthetic CPP-I and CPP-II, but are also uniquely enriched for carbonate-substituted apatite, DNA fragments, small RNA and microbe-derived components. Pathway analysis of protein enrichment predicted the activation of cell death and pro-inflammatory processes by endogenous CPP and synthetic CPP-II alike. This comprehensive characterisation validates the use of CPP-II generated in uraemic serum as in vitro equivalents of their endogenous counterparts and provides insight into the nature and pathological significance of CPP in CKD, which may act as vehicles for various bioactive ligands. Copyright © 2018 Elsevier Inc. All rights reserved.

Radiolytic preparation of thin Au film directly on resin substrate using high-energy electron beam

Energy Technology Data Exchange (ETDEWEB)

Ohkubo, Yuji, E-mail: okubo@upst.eng.osaka-u.ac.jp [Graduate School of Engineering, Osaka University, 2-1 Yamadaoka, Suita, Osaka 565-0871 (Japan); Seino, Satoshi; Nakagawa, Takashi; Kugai, Junichiro [Graduate School of Engineering, Osaka University, 2-1 Yamadaoka, Suita, Osaka 565-0871 (Japan); Ueno, Koji [Japan Electron Beam Irradiation Service Ltd., 5-3 Ozushima, Izumiohtsu, Osaka 595-0074 (Japan); Yamamoto, Takao A. [Graduate School of Engineering, Osaka University, 2-1 Yamadaoka, Suita, Osaka 565-0871 (Japan)

2016-04-01

A novel method for preparing thin Au films directly on resin substrates using an electron beam was developed. The thin Au films were prepared on a resin substrate by the reduction of Au ions in an aqueous solution via irradiation with a high-energy electron beam (4.8 MeV). This reduction method required 7 s of the irradiation time of the electron beam. Furthermore, no reductant or catalyst was needed. As the concentration of Au ions in the precursor solution was increased, the amount of Au deposited on the resin substrate increased, too, and the structure of the prepared Au film changed. As a result, the film color changed as well. Cross-sectional scanning electron microscope images of the thus-prepared Au film indicated that the Au films were consisted of two layers: a particle layer and a bottom bulk layer. There was strong adhesion between the Au films and the underlying resin substrates. This was confirmed by the tape-peeling test and through ultrasonic cleaning. After both processes, Au remained on the resin substrates, while most of the particle-like moieties were removed. This indicated that the thin Au films prepared via irradiation with a high-energy electron beam adhered strongly to the resin substrates. - Highlights: • A thin gold (Au) film was formed by EBIRM for the first time. • The irradiation time of the electron beam was less than 10 s. • Thin Au films were obtained without reductant or catalyst. • Au films were consisted of two layers: a particle layer and a bottom bulk layer. • There was strong adhesion between the bottom bulk layer and the underlying resin substrates.

Transformation from Al3BC phase to doped TiB2 or TiC particles in Al–Ti melts

International Nuclear Information System (INIS)

Tian, Wenjie; Li, Pengting; Gao, Tong; Nie, Jinfeng; Liu, Xiangfa

2013-01-01

Highlights: ► The reaction of phase Al 3 BC with Ti was investigated. ► The transformation leads to the formation of C-doped TiB 2 and B-doped TiC. ► The doped particles show macroporous and lamellar morphologies. ► A model was proposed to illustrate the transformation mechanism. ► Grain refinement performance of the Al–5Ti–0.8B–0.2C on A356 alloy is excellent. -- Abstract: An Al–8B–2C master alloy was added into Al–Ti melts to study the reaction of Al 3 BC phase with Ti. As a result, a new Al–5Ti–0.8B–0.2C master alloy was fabricated. The microstructures were studied by field emission scanning electron microscope (FESEM), X-ray diffraction (XRD) and transmission electron microscope (TEM). The analysis indicates that C-doped TiB 2 and B-doped TiC which show macroporous and lamellar morphologies are transformed from Al 3 BC. The transformation mechanism is also discussed in this work. Furthermore, the grain refinement performance of the Al–5Ti–0.8B–0.2C on A356 alloy was investigated

Modeling Evaporation and Particle Assembly in Colloidal Droplets.

Science.gov (United States)

Zhao, Mingfei; Yong, Xin

2017-06-13

Evaporation-induced assembly of nanoparticles in a drying droplet is of great importance in many engineering applications, including printing, coating, and thin film processing. The investigation of particle dynamics in evaporating droplets can provide fundamental hydrodynamic insight for revealing the processing-structure relationship in the particle self-organization induced by solvent evaporation. We develop a free-energy-based multiphase lattice Boltzmann method coupled with Brownian dynamics to simulate evaporating colloidal droplets on solid substrates with specified wetting properties. The influence of interface-bound nanoparticles on the surface tension and evaporation of a flat liquid-vapor interface is first quantified. The results indicate that the particles at the interface reduce surface tension and enhance evaporation flux. For evaporating particle-covered droplets on substrates with different wetting properties, we characterize the increase of evaporate rate via measuring droplet volume. We find that droplet evaporation is determined by the number density and circumferential distribution of interfacial particles. We further correlate particle dynamics and assembly to the evaporation-induced convection in the bulk and on the surface of droplet. Finally, we observe distinct final deposits from evaporating colloidal droplets with bulk-dispersed and interface-bound particles. In addition, the deposit pattern is also influenced by the equilibrium contact angle of droplet.

Hydrolysis of protein and model dipeptide substrated by attached and nonattached marine Pseudomonas sp. strain NCIMB 2021

International Nuclear Information System (INIS)

Griffith, P.C.; Fletcher, M.

1991-01-01

Rates of substrate hydrolysis by nonattached bacteria and by bacteria attached to particles derived from marine diatom frustules were estimated by using two substrates, a dipeptide analog and a protein. Adsorption of the two substrates onto the particles was also evaluated. Methyl-coumarinyl-amide-leucine (MCA-leucine) was used to estimate hydrolysis of dipeptides by measuring an increase in fluorescence as MCA-leucine was hydrolyzed to leucine and the fluorochrome methylcoumarin. To examine hydrolysis of a larger molecule, was prepared a radiolabeled protein by 14 C-methylation of bovine serum albumin. The rate of protein hydrolysis in samples of particle-attached or nonattached bacteria was estimated by precipitating all nonhydrolyzed protein with cold trichloroacetic acid and then determining the trichloroacetic acid-soluble radiolabeled material, which represented methyl- 14 C-peptides and -amino acids. About 25% of the MCA-leucine adsorbed to the particles. MCA-leucine was hydrolyzed faster by nonattached than attached bacteria, which was probably related to its tendency to remain dissolved in the liquid phase. In contrast, almost 100% of the labeled protein adsorbed to the particles. Accordingly, protein was much less available to nonattached bacteria but was rapidly hydrolyzed by attached bacteria

Improved osteoblasts growth on osteomimetic hydroxyapatite/BaTiO_3 composites with aligned lamellar porous structure

International Nuclear Information System (INIS)

Liu, Beilei; Chen, Liangjian; Shao, Chunsheng; Zhang, Fuqiang; Zhou, Kechao; Cao, Jun; Zhang, Dou

2016-01-01

Osteoblasts growing into bone substitute is an important step of bone regeneration. This study prepared porous hydroxyapatite (HA)/BaTiO_3 piezoelectric composites with porosity of 40%, 50% and 60% by ice-templating method. Effects of HA/BaTiO_3 composites with different porosities, with and without polarizing treatment on adhesion, proliferation and differentiation of osteoblasts were investigated in vitro. Results revealed that cell densities of the porous groups were significantly higher than those of the dense group (p 0.05). The absence of mechanical loading on the polarized samples may account for this. The results indicated that hierarchically porous HA/BaTiO_3 played a favorable part in osteoblasts proliferation, differentiation and adhesion process and is a promising bone substitute material. - Graphical abstract: Aligned porous structure of HA/BaTiO_3 piezoelectric composites prepared by ice-templating method was similar to the lamellar Haversian system in bone tissue. When co-cultured with human osteosarcoma cells (MG63), porous HA/BaTiO_3 composites exhibited remarkable biological activity in promoting proliferation, differentiation and adhesion of MG63 cells. - Highlights: • The aligned porous structure of HA/BaTiO_3 composite was similar to the lamellar Haversian system in bone tissue. • The piezoelectric d_3_3 coefficient of HA/BaTiO_3 with porosity of 50% was 5.0 pC/N, much higher than that of natural bone. • HA/BaTiO_3 with porosity of 50% promoted proliferation, differentiation and adhesion of MG63 cells remarkably.

SALT-INDUCED TRANSITION FROM A MICELLAR TO A LAMELLAR LIQUID-CRYSTALLINE PHASE IN DILUTE MIXTURES OF ANIONIC AND NONIONIC SURFACTANTS IN AQUEOUS-SOLUTION

NARCIS (Netherlands)

SEIN, A; ENGBERTS, JBFN; VANDERLINDEN, E; VANDEPAS, JC

In dilute mixtures of anionic surfactant, sodium dodecylbenzenesulfonate (NaDoBS), and nonionic poly(ethylene oxide) alkyl monoether (C13-15E(7)) a transition from a micellar to a lamellar phase is found at high salting-out electrolyte (NaCit) concentrations. With an increase of the salt

Numerical simulation of transformation-induced microscopic residual stress in ferrite-martensite lamellar steel

International Nuclear Information System (INIS)

Mikami, Y; Inao, A; Mochizuki, M; Toyoda, M

2009-01-01

The effect of transformation-induced microscopic residual stress on fatigue crack propagation behavior of ferrite-martensite lamellar steel was discussed. Fatigue tests of prestrained and non-prestrained specimens were performed. Inflections and branches at ferrite-martensite boundaries were observed in the non-prestrained specimens. On the other hand, less inflections and branches were found in the prestrained specimens. The experimental results showed that the transformation induced microscopic residual stress has influence on the fatigue crack propagation behavior. To estimate the microscopic residual, a numerical simulation method for the calculation of microscopic residual stress stress induced by martensitic transformation was performed. The simulation showed that compressive residual stress was generated in martensite layer, and the result agree with the experimental result that inflections and branches were observed at ferrite-martensite boundaries.

Fatigue life analysis of unexpected failure in a lamellar TiAl alloy

Energy Technology Data Exchange (ETDEWEB)

Chan, K.S.

1999-07-01

Unexpected catastrophic failure occurred in specimens of a lamellar TiAl alloy tested by axial fatigue. The failure initiated at locations away from artificial defects introduced to the specimens as crack starters. Fractographic examination of the fracture surface revealed the presence of featureless, low-energy facets that suggested the catastrophic crack may have initiated in one or more large grains that cleaved on a cleavage plane or an interface. A crack growth analysis of fatigue life of the test specimens suggested that the catastrophic crack propagated at stress intensity levels below the large crack threshold. Furthermore, the catastrophic crack propagated at rates that were higher than the average rates exhibited by small cracks, as well as by the large crack under equivalent stress intensity ranges. Because of this, the conventional life prediction approach based on the large crack growth data grossly overpredicted the fatigue life.

Morphology and hot deformation of lamellar microstructures in zirconium and titanium alloys

International Nuclear Information System (INIS)

Vanderesse, N.

2008-06-01

This study aims at providing a precise description of the lamellar microstructures of two alloys, Zircaloy-4 and TA6V, and at characterizing their deformation at high temperature. New experimental techniques have been developed for these materials: instrumented Jominy end quench test, channel-die with mobile walls, X-ray microtomography. The main results underline the role of the alpha-GB phase formed at the prior beta grain boundaries on the variant selection in Zircaloy-4 and TA6-V. The three dimensional organization of the colonies in TA6V is also revealed for the first time and discussed in relationship with the formation of the microstructure. In hot compressed Zircaloy-4 several mechanisms of strain localization are observed. Twinning activity at 750 C, in particular, is clearly put into evidence. A classification of these heterogeneities is proposed and their influence on the recrystallization is discussed. (author)

A convenient way of manufacturing silicon nanotubes on a silicon substrate

Energy Technology Data Exchange (ETDEWEB)

Zhang, Changchang; Cheng, Heming; Liu, Xiang, E-mail: liuxiang@ahut.edu.cn

2016-07-01

A convenient approach of preparing silicon nanotubes (SiNTs) on a silicon substrate is described in this work in detail. Firstly, a porous silicon (PSi) slice is prepared by a galvanic displacement reaction. Then it is put into aqueous solutions of 20% (w%) ammonium fluoride and 2.5 mM cobalt nitrate for a predetermined time. The cobalt ions are reduced and the resulted cobalt particles are deposited on the PSi slice. After the cobalt particles are removed with 5 M nitric acid a plenty of SiNTs come out and exhibit disorderly on the silicon substrate, which are illustrated by scanning electron microscopy (SEM). The compositions of the SiNTs are examined by energy-dispersive X-ray spectroscopy. Based on the SEM images, a suggested mechanism is put forward to explain the generation of the SiNTs on the PSi substrate. - Highlights: • A facile approach of preparing silicon nano tubes was invented. • The experimental results demonstrated the strong reducibility of Si-H{sub x} species. • It provided a new way of manufacturing silicon-contained hybrids.

Optimizing Polymer Lab-on-Chip Platforms for Ultrasonic Manipulation: Influence of the Substrate

Directory of Open Access Journals (Sweden)

Itziar González

2015-05-01

Full Text Available The choice of substrate material in a chip that combines ultrasound with microfluidics for handling biological and synthetic microparticles can have a profound effect on the performance of the device. This is due to the high surface-to-volume ratio that exists within such small structures and acquires particular relevance in polymer-based resonators with 3D standing waves. This paper presents three chips developed to perform particle flow-through separation by ultrasound based on a polymeric SU-8 layer containing channelization over three different substrates: Polymethyl methacrylate (PMMA; Pyrex; and a cracked PMMA composite-like structure. Through direct observations of polystyrene microbeads inside the channel, the three checked chips exhibit their potential as disposable continuous concentration devices with different spatial pressure patterns at frequencies of resonance close to 1 Mhz. Chips with Pyrex and cracked PMMA substrates show restrictions on the number of pressure nodes established in the channel associated with the inhibition of 3D modes in the solid structure. The glass-substrate chip presents some advantages associated with lower energy requirements to collect particles. According to the results, the use of polymer-based chips with rigid substrates can be advantageous for applications that require short treatment times (clinical tests handling human samples and low-cost fabrication.

Heat and water transfer in a rotating drum containing solid substrate particles

NARCIS (Netherlands)

Schutyser, M.A.I.; Weber, F.J.; Briels, W.J.; Rinzema, A.; Boom, R.M.

2003-01-01

In previous work we reported on the simulation of mixing behavior of a slowly rotating drum for solid-state fermentation (SSF) using a discrete particle model. In this investigation the discrete particle model is extended with heat and moisture transfer. Heat transfer is implemented in the model via

Evaluation of preparation methods for suspended nano-objects on substrates for dimensional measurements by atomic force microscopy

Directory of Open Access Journals (Sweden)

Petra Fiala

2017-08-01

Full Text Available Dimensional measurements on nano-objects by atomic force microscopy (AFM require samples of safely fixed and well individualized particles with a suitable surface-specific particle number on flat and clean substrates. Several known and proven particle preparation methods, i.e., membrane filtration, drying, rinsing, dip coating as well as electrostatic and thermal precipitation, were performed by means of scanning electron microscopy to examine their suitability for preparing samples for dimensional AFM measurements. Different suspensions of nano-objects (with varying material, size and shape stabilized in aqueous solutions were prepared therefore on different flat substrates. The drop-drying method was found to be the most suitable one for the analysed suspensions, because it does not require expensive dedicated equipment and led to a uniform local distribution of individualized nano-objects. Traceable AFM measurements based on Si and SiO2 coated substrates confirmed the suitability of this technique.

Evaluation of preparation methods for suspended nano-objects on substrates for dimensional measurements by atomic force microscopy.

Science.gov (United States)

Fiala, Petra; Göhler, Daniel; Wessely, Benno; Stintz, Michael; Lazzerini, Giovanni Mattia; Yacoot, Andrew

2017-01-01

Dimensional measurements on nano-objects by atomic force microscopy (AFM) require samples of safely fixed and well individualized particles with a suitable surface-specific particle number on flat and clean substrates. Several known and proven particle preparation methods, i.e., membrane filtration, drying, rinsing, dip coating as well as electrostatic and thermal precipitation, were performed by means of scanning electron microscopy to examine their suitability for preparing samples for dimensional AFM measurements. Different suspensions of nano-objects (with varying material, size and shape) stabilized in aqueous solutions were prepared therefore on different flat substrates. The drop-drying method was found to be the most suitable one for the analysed suspensions, because it does not require expensive dedicated equipment and led to a uniform local distribution of individualized nano-objects. Traceable AFM measurements based on Si and SiO 2 coated substrates confirmed the suitability of this technique.

Gold Wire-networks: Particle Array Guided Evaporation Lithograpy

KAUST Repository

Lone, Saifullah

2015-06-29

We exploited the combination of dry deposition of monolayer of 2D (two dimensional) templates, lift-up transfer of 2D template onto flat surfaces and evaporation lithography [1] to fabricate gold micro- and submicron size wire networks. The approach relies upon the defect free dry deposition of 2D monolayer of latex particles [2] on patterned silicon template and flat PDMS-substrate to create square centered and honey-comb wire networks respectively. The process is followed by lift-up transfer of 2D latex crystal on glass substrate. Subsequently, a small amount of AuNP-suspension is doped on top of the transferred crystal; the suspension is allowed to spread instantaneously and dried at low temperature. The liquid evaporates uniformly to the direction perpendicular to glass substrate. During evaporation, AuNPs are de-wetted along with the movement of liquid to self-assemble in-between the inter-particle spaces and therefore, giving rise to liquid-bridge networks which upon delayed evaporation, transforms into wire networks. The approach is used to fabricate both micro- and submicron wire-networks by simply changing the template dimensions. One of the prime motives behind this study is to down-scale the existing particle array template-based evaporation lithography process to fabricate connected gold wire networks at both micro- and submicron scale. Secondly, the idea of combining the patterned silicon wafer with lifted latex particle template creates an opportunity to clean and res-use the patterned wafer more often and thereby, saving fabrication time and resources. Finally, we illustrated the validity of this approach by creating an easy and high-speed approach to develop gold wire networks on a flexible substrate with a thin deposited adhesive. These advances will not only serve as a platform to scale up the production, but also demonstrated that the fabrication method can produce metallic wire networks of different scale and onto a variety of substrates.

Adhesion mechanisms of nanoparticle silver to substrate materials: identification

International Nuclear Information System (INIS)

Joo, Sungchul; Baldwin, Daniel F

2010-01-01

Nanoparticle silver (NPS) conductors are increasingly being investigated for printed electronics applications. However, the adhesion mechanism of the nanoparticle silver to substrate materials has not been identified yet. In particular, the adhesion of NPS to organic materials such as the widely used polyimide Kapton HN and Kapton FPC dry films is concerned with low adhesion strength because the processed polymer surface is chemically inert. Moreover, its adhesion to substrate materials such as benzocyclobutene (BCB), copper and aluminum was found to be very weak. Therefore, in this paper, the mechanisms of NPS adhesion to organic and inorganic materials are identified as the first step in improving NPS adhesion strength. Improving the adhesion strength of NPS will be the key issue for printed electronics applications. The adhesion of NPS to substrate materials was found to be mainly attributed to van der Waals forces based on particle adhesion mechanisms. This finding provides the initiative of developing an adhesion prediction model of NPS to substrate materials in order to provide guidelines for improving the NPS adhesion strength to the substrate materials used in printed electronics.

Tunable inkjet-printed slotted waveguide antenna on a ferrite substrate

KAUST Repository

Nafe, Ahmed

2015-04-13

In this work an inkjet-printed frequency-tunable slotted waveguide antenna on a ferrite substrate is reported. Unlike the typical substrate integrated waveguide approach with via holes, a true 3D rectangular waveguide is realized by inkjet-printing of nano-particle based conductive ink on the broad faces as well as on sides of the substrate. The operating frequency of the antenna can be tuned by applying a variable static bias magnetic field that controls the permeability of the host ferrite substrate. The antenna operates about a center frequency of approximately 14 GHz with an instantaneous impedance bandwidth of 75 MHz. A fabricated prototype has demonstrated a tuning range of 10% (1.5 GHz) using an applied bias magnetic field of 3 kOe yielding it especially attractive for tunable and reconfigurable yet low cost microwave systems.

Stiff, porous scaffolds from magnetized alumina particles aligned by magnetic freeze casting.

Science.gov (United States)

Frank, Michael B; Naleway, Steven E; Haroush, Tsuk; Liu, Chin-Hung; Siu, Sze Hei; Ng, Jerry; Torres, Ivan; Ismail, Ali; Karandikar, Keyur; Porter, Michael M; Graeve, Olivia A; McKittrick, Joanna

2017-08-01

Bone consists of a hard mineral phase and a compliant biopolymer phase resulting in a composite material that is both lightweight and strong. Osteoporosis that degrades spongy bone preferentially over time leads to bone brittleness in the elderly. A porous ceramic material that can mimic spongy bone for a one-time implant provides a potential solution for the future needs of an aging population. Scaffolds made by magnetic freeze casting resemble the aligned porosity of spongy bone. A magnetic field applied throughout freezing induces particle chaining and alignment of lamellae structures between growing ice crystals. After freeze drying to extract the ice and sintering to strengthen the scaffold, cubes from the scaffold center are mechanically compressed along longitudinal (z-axis, ice growth direction) and transverse (y-axis, magnetic field direction) axes. The best alignment of lamellar walls in the scaffold center occurs when applying magnetic freeze casting with the largest particles (350nm) at an intermediate magnetic field strength (75mT), which also agrees with stiffness enhancement results in both z and y-axes. Magnetic moments of different sized magnetized alumina particles help determine the ideal magnetic field strength needed to induce alignment in the scaffold center rather than just at the poles. Copyright © 2017 Elsevier B.V. All rights reserved.

DNA-assisted binding of microspheres on glass substrates and their laser-induced release

International Nuclear Information System (INIS)

Kim, Sejong; Geiss, Erik; Yu, Phillip; Papadimitrakopoulos, Fotios; Marcus, Harris L.

2006-01-01

DNA hybridization has been increasingly adopted in materials sciences due to its complementary nature of single stranded DNAs. This unique property could be potentially used in the realization of 2 dimensional (2D) arrays of colloidal microspheres as a precursor to further build more complicated superstructures. In order to precisely understand this DNA-assisted assembly of colloidal particles, we quantitatively assessed the surface density of grafted and hybridizing accessible DNA oligomers on both substrate and colloidal particles. The DNA grafting densities were determined by UV-Vis of dye-functionalized complementary DNA oligomers, in conjunction with theoretical models. The variations of the concentration of hybridized DNA as a function of parameters such as the number of DNA base pairs (bp), the length of spacer and the size of sphere were also investigated to determine the immobilization strength of colloidal microspheres on the substrate. Dehybridization of the particle was conducted by utilizing a focused laser beam. These results were also compared with the particle hybridization energies and modeled according to the sum of DNA bindings as a function of the number of hybridized bases

Morphologies and growth mechanisms of the eutectic particles in as-cast Al-Mg-Sc alloy; Morphologien und Wachstumsmechanismen eutektischer Partikel in Al-Mg-Sc-Legierung im Gusszustand

Energy Technology Data Exchange (ETDEWEB)

Pan, Dejiang; Zhou, Shi' ang; Li, Heng [Hefei Univ. of Technology (China); Zhang, Zhen; Wu, Yucheng [Laboratories of Nonferrous Metal Material and Processing Engineering of Anhui Province, Hefei (China); Li, Ming [Anhui Jianghuai Automobile Co., Ltd, Hefei (China)

2017-04-15

Primary particles with faceted cubic morphology were produced in as-cast Al-Mg alloy due to the addition of Sc. The cross-section of the particles revealed some eutectic structure composed of multilayer of 'Al{sub 3}Sc + α-Al + Al{sub 3}Sc..'. At the cooling rate of 200 - 300 K/s, Al{sub 3}Sc primary phase nucleated initially on oxides within the melt and developed to a cubic structure with a 'cellular-dendritic' mode of growth. The formation of α-Al structural shells was attributed as a reason for the segregation of Mg-rich lamellar dendrites at later stages. A growth mechanism for multilayer structure was proposed using the results presented.

Fragmentation of α2 plates in a fully lamellar TiAl during creep

International Nuclear Information System (INIS)

Wang, J.G.; Hsiung, L.M.; Nieh, T.G.

1999-01-01

The fragmentation and spheroidization of α 2 laths in a fully-lamellar TiAl alloy during creep were examined. Three possible mechanisms, Rayleigh's perturbation model, subgrain boundary groove mechanism and intersection of deformation twins with α 2 lamellae were presented and discussed. During creep deformation, the pile-up of interfacial dislocations leads to a change of planar interface, which, in turn, causes a difference in local chemical potential, and further results in the spheroidization of α 2 lamellae. On the other hand, the deformation of the α 2 phase is expected to be induced by the high local stress concentration introduced by the pile up of interfacial dislocations. The dynamic recovery process may lead to the formation of subgrain boundaries in the α 2 lamellae, which results in the spheroidization and termination of α 2 lamellae with the aid of diffusion during creep

2D mesoscale colloidal crystal patterns on polymer substrates

Science.gov (United States)

Bredikhin, Vladimir; Bityurin, Nikita

2018-05-01

The development of nanosphere lithography relies on the ability of depositing 2D colloidal crystals comprising micro- and nano-size elements on substrates of different materials. One of the most difficult problems here is deposition of coatings on hydrophobic substrates, e.g. polymers, from aqueous colloidal solutions. We use UV photooxidation for substrate hydrophilization. We demonstrate a new method of producing a two-dimensional ordered array of polymer microparticles (polystyrene microspheres ∼1 μm in diameter) on a polymer substrate (PMMA). We show that implementation of the new deposition technique for directed self-assembly of microspheres on an UV irradiated surface provides an opportunity to obtain coatings on a hydrophilized PMMA surface of large area (∼5 cm2). UV irradiation of the surface through masks allows creating 2D patterns consisting of mesoscale elements formed by the deposited self-assembled microparticles owing to the fact that the colloidal particles are deposited only on the irradiated area leaving the non-irradiated sections intact.

Investigation of Dendrite Coarsening in Complex Shaped Lamellar Graphite Iron Castings

Directory of Open Access Journals (Sweden)

Péter Svidró

2017-07-01

Full Text Available Shrinkage porosity and metal expansion penetration are two casting defects that appear frequently during the production of complex-shaped lamellar graphite iron components. These casting defects are formed during the solidification and usually form in the part of the casting which solidifies last. The position of the area that solidifies last is dependent on the thermal conditions. Test castings with thermal conditions like those existing in a complex-shaped casting were successfully applied to provoke a shrinkage porosity defect and a metal expansion penetration defect. The investigation of the primary dendrite morphology in the defected positions indicates a maximum intradendritic space, where the shrinkage porosity and metal expansion penetration defects appear. Moving away from the defect formation area, the intradendritic space decreases. A comparison of the intradendritic space with the simulated local solidification times indicates a strong relationship, which can be explained by the dynamic coarsening process. More specifically, long local solidification times facilitates the formation of a locally coarsened austenite morphology. This, in turn, enables the formation of a shrinkage porosity or a metal expansion penetration.

Interaction of metallic nanoparticles with dielectric substrates: effect of optical constants

International Nuclear Information System (INIS)

Hutter, Tanya; Elliott, Stephen R; Mahajan, Sumeet

2013-01-01

In this paper, we study the local-field enhancement in a system of a metallic nanoparticle placed very near to a dielectric substrate. In such systems, intense electric fields are localized in the gap between the particle and the substrate, creating a ‘hot-spot’ under appropriate excitation conditions. We use finite-element numerical simulations in order to study the field enhancement in this dielectric–metal system. More specifically, we show how the optical properties of the dielectric substrate (n and k) affect the plasmonic field enhancement in the nano-gap. We also analyze the degree of field confinement in the gap and discuss it in the context of utilization for surface-enhanced Raman scattering. We finally show the fields generated by real substrates and compare them to metallic ones. (paper)

Electrostatic deposition of a micro solder particle using a single probe by applying a single rectangular pulse

International Nuclear Information System (INIS)

Nakabayashi, Daizo; Sawai, Kenji; Saito, Shigeki; Takahashi, Kunio

2012-01-01

Recently, micromanipulation techniques have been in high demand. A technique to deposit a metal microparticle onto a metal substrate by using a single metal probe has been proposed as one of the techniques. A solder particle with a diameter of 20–30 µm, initially adhering to the probe tip, is detached and deposited onto a substrate. The success rate of the particle deposition was 44% in the previous research, and is insufficient for industrial applications. In this paper, a technique of particle deposition by applying a single rectangular pulse is proposed, and the mechanism of the deposition is described. In the mechanism, an electric discharge between the probe and the particle when the particle reaches the substrate plays an important role in the particle deposition. Moreover, the mechanism of the proposed technique is verified by experiments of particle deposition, which are observed using a high-speed camera, a scanning electron microscope (SEM) and an oscilloscope. The success rate of the particle deposition has increased to 93% by the proposed technique. Furthermore, the damage to the particle by the electric discharge is evaluated using an RC circuit model, and the applicability of the proposed technique is discussed. (paper)

Study of lamellar structure and crystallization behavior of poly(butylene terephthalate (PBT) in PBT/ABS and PBT/ABS/MMA-GMA blends using DSC, SAXS and DMTA

International Nuclear Information System (INIS)

Mantovani, Gerson L.; Pessan, Luiz A.; Hage, Elias; Torriani, Iris L.

2001-01-01

The effects of processing conditions and blend composition in the crystallization behaviour and lamellar structure of poly(butylene terephthalate) (PBT) in blends with acrylonitrile-butadiene-styrene copolymer (ABS) were studied. Differential scanning calorimetry (DSC), small-angle X-ray scattering (SAXS) and dynamic mechanical thermal analysis (DMTA) were used to observe those effects. Addition of reactive acrylic compatibilizer to the PBT/ABS blends has promoted an increase in the heat of crystallization of the related blends. The Long Period (L), obtained from the peak in the Lorentz-corrected SAXS pattern, was used to observe the effect in the lamellar structure of PBT phase in the blends. The results were in good agreement with the calculated values from de correlation function and the values of L do not show a significant dependence with the PBT mass fraction, either in the binary blends (PBT/ABS) or in the compatibilized blends. A slight but clear increase of the long period (from 3 to 5 angstrom) is noted for the systems injection molded at 240 deg C when compared to the ones molded at 260 deg C, although PBT crystallinity in the blends does not change significantly with blend composition or processing conditions. DMTA curves show a slight shift in the temperature of the tan δ main peaks for both PBT and ABS phases in the compatibilized blends, thereby indicating changes in the degree of miscibility or interaction between phases of those blends. Changes in the compatibilized blends miscibility may be responsible by the effects in the crystallization behaviour and lamellar structure of the PBT/ABS blends. (author)

Study of lamellar structure and crystallization behavior of poly(butylene terephthalate (PBT) in PBT/ABS and PBT/ABS/MMA-GMA blends using DSC, SAXS and DMTA

Energy Technology Data Exchange (ETDEWEB)

Mantovani, Gerson L.; Pessan, Luiz A.; Hage, Elias [Sao Carlos Univ., SP (Brazil). Dept. de Engenharia de Materiais]. E-mail: elias@power.ufscar.br; Plivelic, Tomas S. [Laboratorio Nacional de Luz Sincrotron (LNLS), Campinas, SP (Brazil); Torriani, Iris L. [Universidade Estadual de Campinas, SP (Brazil). Inst. de Fisica Gleb Wataghin

2001-07-01

The effects of processing conditions and blend composition in the crystallization behaviour and lamellar structure of poly(butylene terephthalate) (PBT) in blends with acrylonitrile-butadiene-styrene copolymer (ABS) were studied. Differential scanning calorimetry (DSC), small-angle X-ray scattering (SAXS) and dynamic mechanical thermal analysis (DMTA) were used to observe those effects. Addition of reactive acrylic compatibilizer to the PBT/ABS blends has promoted an increase in the heat of crystallization of the related blends. The Long Period (L), obtained from the peak in the Lorentz-corrected SAXS pattern, was used to observe the effect in the lamellar structure of PBT phase in the blends. The results were in good agreement with the calculated values from de correlation function and the values of L do not show a significant dependence with the PBT mass fraction, either in the binary blends (PBT/ABS) or in the compatibilized blends. A slight but clear increase of the long period (from 3 to 5 angstrom) is noted for the systems injection molded at 240 deg C when compared to the ones molded at 260 deg C, although PBT crystallinity in the blends does not change significantly with blend composition or processing conditions. DMTA curves show a slight shift in the temperature of the tan {delta} main peaks for both PBT and ABS phases in the compatibilized blends, thereby indicating changes in the degree of miscibility or interaction between phases of those blends. Changes in the compatibilized blends miscibility may be responsible by the effects in the crystallization behaviour and lamellar structure of the PBT/ABS blends. (author)

Effect of substrate interface on the magnetism of supported iron nanoparticles

Energy Technology Data Exchange (ETDEWEB)

Balan, A. [Swiss Light Source, Paul Scherrer Institut (PSI), Villigen CH-5232 (Switzerland); Fraile Rodríguez, A. [Departament de Física Fonamental and Institut de Nanociència i Nanotecnologia (IN2UB), Universitat de Barcelona, E-08028 Barcelona (Spain); Vaz, C.A.F.; Kleibert, A.; Nolting, F. [Swiss Light Source, Paul Scherrer Institut (PSI), Villigen CH-5232 (Switzerland)

2015-12-15

In situ X-ray photo-emission electron microscopy is used to investigate the magnetic properties of iron nanoparticles deposited on different single crystalline substrates, including Si(001), Cu(001), W(110), and NiO(001). We find that, in our room temperature experiments, Fe nanoparticles deposited on Si(001) and Cu(001) show both superparamagnetic and magnetically stable (blocked) ferromagnetic states, while Fe nanoparticles deposited on W(110) and NiO(001) show only superparamagnetic behaviour. The dependence of the magnetic behaviour of the Fe nanoparticles on the contact surface is ascribed to the different interfacial bonding energies, higher for W and NiO, and to a possible relaxation of point defects within the core of the nanoparticles on these substrates, that have been suggested to stabilise the ferromagnetic state at room temperature when deposited on more inert surfaces such as Si and Cu. - Highlights: • In situ X-ray photo-emission electron microscopy study on iron nanoparticles. • Magnetically blocked particles are found on Si(001) and Cu(001). • Superparamagnetic particles are found on W(110) and Ni0(001). • The substrate dependent behavior is ascribed to the different bonding energies.

Polypyrrole Coated Cellulosic Substrate Modified by Copper Oxide as Electrode for Nitrate Electroreduction

Science.gov (United States)

Hamam, A.; Oukil, D.; Dib, A.; Hammache, H.; Makhloufi, L.; Saidani, B.

2015-08-01

The aim of this work is to synthesize polypyrrole (PPy) films on nonconducting cellulosic substrate and modified by copper oxide particles for use in the nitrate electroreduction process. Firstly, the chemical polymerization of polypyrrole onto cellulosic substrate is conducted by using FeCl3 as an oxidant and pyrrole as monomer. The thickness and topography of the different PPy films obtained were estimated using a profilometer apparatus. The electrochemical reactivity of the obtained electrodes was tested by voltamperometry technique and electrochemical impedance spectroscopy. Secondly, the modification of the PPy film surface by incorporation of copper oxide particles is conducted by applying a galvanostatic procedure from a CuCl2 solution. The SEM, EDX and XRD analysis showed the presence of CuO particles in the polymer films with dimensions less than 50 nm. From cyclic voltamperometry experiments, the composite activity for the nitrate electroreduction reaction was evaluated and the peak of nitrate reduction is found to vary linearly with initial nitrate concentration.

Exploiting evanescent-wave amplification for subwavelength low-contrast particle detection

Science.gov (United States)

Roy, S.; Pereira, S. F.; Urbach, H. P.; Wei, Xukang; El Gawhary, O.

2017-07-01

The classical problem of subwavelength particle detection on a flat surface is especially challenging when the refractive index of the particle is close to that of the substrate. We demonstrate a method to improve the detection ability several times for such a situation, by enhancing the "forbidden" evanescent waves in the substrate using the principle of super-resolution with evanescent waves amplification. The working mechanism of the system and experimental validation from a design with a thin single dielectric layer is presented. The resulting system is a simple but complete example of evanescent-wave generation, amplification, and the consequent modulation of the far field. This principle can have far reaching impact in the field of particle detection in several applications ranging from contamination control to interferometric scattering microscopy for biological samples.

The impact of green roof ageing on substrate characteristics and hydrological performance

Science.gov (United States)

De-Ville, Simon; Menon, Manoj; Jia, Xiaodong; Reed, George; Stovin, Virginia

2017-04-01

Green roofs contribute to stormwater management through the retention of rainfall and the detention of runoff. However, there is very limited knowledge concerning the evolution of green roof hydrological performance with system age. This study presents a non-invasive technique which allows for repeatable determination of key substrate characteristics over time, and evaluates the impact of observed substrate changes on hydrological performance. The physical properties of 12 green roof substrate cores have been evaluated using non-invasive X-ray microtomography (XMT) imaging. The cores comprised three replicates of two contrasting substrate types at two different ages: unused virgin samples; and 5-year-old samples from existing green roof test beds. Whilst significant structural differences (density, pore and particle sizes, tortuosity) between virgin and aged samples of a crushed brick substrate were observed, these differences did not significantly affect hydrological characteristics (maximum water holding capacity and saturated hydraulic conductivity). A contrasting substrate based upon a light expanded clay aggregate experienced increases in the number of fine particles and pores over time, which led to increases in maximum water holding capacity of 7%. In both substrates, the saturated hydraulic conductivity estimated from the XMT images was lower in aged compared with virgin samples. Comparisons between physically-derived and XMT-derived substrate hydrological properties showed that similar values and trends in the data were identified, confirming the suitability of the non-invasive XMT technique for monitoring changes in engineered substrates over time. The observed effects of ageing on hydrological performance were modelled as two distinct hydrological processes, retention and detention. Retention performance was determined via a moisture-flux model using physically-derived values of virgin and aged maximum water holding capacity. Increased water holding

Development of vapor deposited silica sol-gel particles for use as a bioactive materials system.

Science.gov (United States)

Snyder, Katherine L; Holmes, Hallie R; VanWagner, Michael J; Hartman, Natalie J; Rajachar, Rupak M

2013-06-01

Silica-based sol-gel and bioglass materials are used in a variety of biomedical applications including the surface modification of orthopedic implants and tissue engineering scaffolds. In this work, a simple system for vapor depositing silica sol-gel nano- and micro-particles onto substrates using nebulizer technology has been developed and characterized. Particle morphology, size distribution, and degradation can easily be controlled through key formulation and manufacturing parameters including water:alkoxide molar ratio, pH, deposition time, and substrate character. These particles can be used as a means to rapidly modify substrate surface properties, including surface hydrophobicity (contact angle changes >15°) and roughness (RMS roughness changes of up to 300 nm), creating unique surface topography. Ions (calcium and phosphate) were successfully incorporated into particles, and induced apatitie-like mineral formation upon exposure to simulated body fluid Preosteoblasts (MC3T3) cultured with these particles showed up to twice the adhesivity within 48 h when compared to controls, potentially indicating an increase in cell proliferation, with the effect likely due to both the modified substrate properties as well as the release of silica ions. This novel method has the potential to be used with implants and tissue engineering materials to influence cell behavior including attachment, proliferation, and differentiation via cell-material interactions to promote osteogenesis. Copyright © 2012 Wiley Periodicals, Inc.

The Effect of Substrate-Bulk Interaction on Hydrolysis Modeling in Anaerobic Digestion Process

Directory of Open Access Journals (Sweden)

Antonio Panico

2014-11-01

Full Text Available In an Anaerobic Digestion (AD process treating particulate substrates, the size of solids is expected to negatively affect the rate of hydrolysis step and consequently influence the performance of the whole process. To avoid any disadvantage due to size of solids, expensive pre-treatments aimed at disintegrating and solubilizing substrates are commonly conducted prior to AD. This practice is doubtlessly successful, but not always necessary, since some organic substrates, although particulate, once immersed in water, tend to solubilize immediately. This aspect, if properly considered, could result in saving money and time in the AD process, as well as refining the development and calibration of AD mathematical models. The present study is actually aimed at demonstrating, through experiments and mathematical simulations, different results deriving from the AD process performed, under the same operating conditions, on two different substrates, i.e. homemade pasta and carrot batons, having the same particle size, but different chemical composition and texture. Experimental outcomes highlighted the effect of particles size on bio-methane production only from the bio-methanation potential tests (BMP conducted on carrot batons. Similar results were obtained by mathematical model calibration, i.e., different kinetic constants for differently-sized carrot batons and same kinetic constant for differently-sized homemade pasta solids.

Simulations of magnetorheological suspensions in Poiseuille flow

Energy Technology Data Exchange (ETDEWEB)

Pappas, Yannis; Klingenberg, Daniel J. [University of Wisconsin-Madison, Department of Chemical and Biological Engineering, Madison, WI (United States)

2006-06-15

Particle-level simulations are conducted to study magnetorheological fluids in plane Poiseuille flow. The importance of the boundary conditions for the particles at the channel walls is examined by considering two extreme cases: no friction and infinite coefficient of friction. The inclusion of friction produces Bingham fluid behavior, as commonly observed experimentally for MR suspensions. Lamellar structures, similar to those reported for electrorheological fluids in shear flow, are observed in the post-yield region for both particle boundary conditions. The formation of these lamellae is accompanied by an increase in the bulk fluid velocity. The slip boundary condition produces higher fluid velocities and thicker lamellar structures. (orig.)

Vector assembly of colloids on monolayer substrates

Science.gov (United States)

Jiang, Lingxiang; Yang, Shenyu; Tsang, Boyce; Tu, Mei; Granick, Steve

2017-06-01

The key to spontaneous and directed assembly is to encode the desired assembly information to building blocks in a programmable and efficient way. In computer graphics, raster graphics encodes images on a single-pixel level, conferring fine details at the expense of large file sizes, whereas vector graphics encrypts shape information into vectors that allow small file sizes and operational transformations. Here, we adapt this raster/vector concept to a 2D colloidal system and realize `vector assembly' by manipulating particles on a colloidal monolayer substrate with optical tweezers. In contrast to raster assembly that assigns optical tweezers to each particle, vector assembly requires a minimal number of optical tweezers that allow operations like chain elongation and shortening. This vector approach enables simple uniform particles to form a vast collection of colloidal arenes and colloidenes, the spontaneous dissociation of which is achieved with precision and stage-by-stage complexity by simply removing the optical tweezers.

Formation of structural steady states in lamellar/sponge phase-separating fluids under shear flow

Science.gov (United States)

Panizza, P.; Courbin, L.; Cristobal, G.; Rouch, J.; Narayanan, T.

2003-05-01

We investigate the effect of shear flow on a lamellar-sponge phase-separating fluid when subjected to shear flow. We show the existence of two different steady states (droplets and ribbons structures) whose nature does not depend on the way to reach the two-phase unstable region of the phase diagram (temperature quench or stirring). The transition between ribbons and droplets is shear thickening and its nature strongly depends on what dynamical variable is imposed. If the stress is fixed, flow visualization shows the existence of shear bands at the transition, characteristic of coexistence in the cell between ribbons and droplets. In this shear-banding region, the viscosity oscillates. When the shear rate is fixed, no shear bands are observed. Instead, the transition exhibits a hysteretic behavior leading to a structural bi-stability of the phase-separating fluid under flow.

Small-angle neutron scattering investigation of the chain conformation of lamellar polystyrene/isoprene phase in solid state

International Nuclear Information System (INIS)

Constantinescu, L.M.

1994-01-01

Small-angle neutron scattering has been used in the study of chain conformation of lamellar styrene/isoprene block copolymers oriented in large single crystals. The radius of gyration of deuterated polystyrene chains around the normal to the interface has been measured. By comparing this direct evolution of the lateral dimension of the chains with the average chain separation given by the molecular area (the surface available at the interface for each covalent bond linking the blocks together) we characterized the transverse interpenetration degree of the chains. The polystyrene chains are displayed in simple strata own micro-domains, without an important interpenetration. (Author) 9 Figs., 2 Tabs., 25 Refs

POLYPYRROLE COATED CELLULOSIC SUBSTRATE MODIFIED BY COPPER OXIDE AS ELECTRODE FOR NITRATE ELECTROREDUCTION

OpenAIRE

A. HAMAM; D. OUKIL; A. DIB; H. HAMMACHE; L. MAKHLOUFI; B. SAIDANI

2015-01-01

The aim of this work is to synthesize polypyrrole (PPy) films on nonconducting cellulosic substrate and modified by copper oxide particles for use in the nitrate electroreduction process. Firstly, the chemical polymerization of polypyrrole onto cellulosic substrate is conducted by using FeCl3 as an oxidant and pyrrole as monomer. The thickness and topography of the different PPy films obtained were estimated using a profilometer apparatus. The electrochemical reactivity of the obtained electr...

Factors that determine the presence of particles in YBCO films grown by PLD

International Nuclear Information System (INIS)

Barrales-Guadarrama, V R; Rodríguez-Rodríguez, E M; Barrales-Guadarrama, R; Reyes Ayala, N

2017-01-01

The method of growing thin films PLD, is widely used in applications and possesses great potential in thin YBa 2 Cu 3 O 7-δ films production with outstanding physical properties. However, it is limited in nano and micro technology due to the presence of particles on the surface of the films. This article describes some causes that create these particles. YBa 2 Cu 3 O 7-δ films have been grown on electrolytic copper used as a variable model the distance target-substrate. The effects are studied through Scanning Electronic Microscopy. It is observed particles with a large variety of shapes and distributions. The results show that ranging the target-substrate distance, the superficial morphology is modified. An evidence of it, is that the evaporation of d B-S = 7 cm, is more coherent that d B-S = 3 cm. Therefore, exist a relation between the morphology and the parameters of growing. Also affect, the structural change that exists among the substrate and the film formation, the substrate preparation and it must not be monocrystalline, these factors define a kinetic and a mechanism of growing that promotes a heterogeneous nucleation. (paper)

SYNTHESIS OF MULTI-LAYER SUBSTRATE FOR OBSERVING OF HYDROXYBENZOIC ACIDS MOLECULES BY SERS

Directory of Open Access Journals (Sweden)

E. A. Yasenko

2015-05-01

Full Text Available Subject of study. The paper deals with the results of the multilayer substrate synthesis having an effect of SERS from hydroxybenzoic acid molecules which are adsorbed on its surface. Methods. To produce SERS substrate we have applied colloid chemistry methods: washing of colloids using a laboratory centrifuge OPn-8, carrying out serial chemical reactions for modifying the surface of semiconductor particles of SiO2 in the solution, determining the maximum of the absorption spectrum of the substrate obtained (in the range from 400 to 1000 nm. To observe hydroxybenzoic acids molecules the method of Raman scattering on OPTEC-785 Video-M spectrometer has been used. Main results. A new method of the substrate chemical synthesis is proposed, which has the effect of SERS by radiationexcitation wavelength of 785 nm, based on micron silica particles with immobilized surface of gold and silver. Raman spectra of hydroxybenzoic acids (Gallic and p-hydroxybenzoic in free and adsorbed state have been experimentally obtained and interpreted. It was shown that both acids in a crystalline state are in the form of dimers. Also, the presence of a certain group of characteristic bands indicates that the hydroxybenzoic acid is chemically bonded to the substrate surface through an oxygen bridge of deprotonated hydroxyl groups. However, unlike Gallic acid, p-hydroxybenzoic acid passes into the monomer form. Practical significance. This technique for enhancing substrate preparation is usable in the laboratory without sophisticated technical equipment. Experimental data on the method of securing the hydroxybenzoic acids and form of their existence on the surface of the substrate will be useful in the design of sensor systems based on them. Characteristic bands of undistorted aromatic ring of hydroxybenzoic acids may also be used in developing

SERS substrates fabricated using ceramic filters for the detection of bacteria

Science.gov (United States)

Mosier-Boss, P. A.; Sorensen, K. C.; George, R. D.; Obraztsova, A.

2016-01-01

SERS substrates were fabricated by filtering either Ag or Au colloidal particles onto rigid, ceramic filters - onto which suspensions of bacteria were then filtered. SERS spectra of the bacteria were obtained using a Raman spectrometer that has an 'orbital raster scan' capability. It was shown that bacteria samples prepared in this manner were uniformly distributed onto the surface of the SERS substrate. The effect of common buffer systems on the SERS spectra was investigated and the utility of using the SERS technique for speciation of bacteria was explored.

Controlling the radiative properties of cool black-color coatings pigmented with CuO submicron particles

International Nuclear Information System (INIS)

Gonome, Hiroki; Baneshi, Mehdi; Okajima, Junnosuke; Komiya, Atsuki; Maruyama, Shigenao

2014-01-01

The objective of this study was to design a pigmented coating with dark appearance that maintains a low temperature while exposed to sunlight. The radiative properties of a black-color coating pigmented with copper oxide (CuO) submicron particles are described. In the present work, the spectral behavior of the CuO-pigmented coating was calculated. The radiative properties of CuO particles were evaluated, and the radiative transfer in the pigmented coating was modeled using the radiation element method by ray emission model (REM 2 ). The coating is made using optimized particles. The reflectivity is measured by spectroscopy and an integrating sphere in the visible (VIS) and near infrared (NIR) regions. By using CuO particles controlled in size, we were able to design a black-color coating with high reflectance in the NIR region. The coating substrate also plays an important role in controlling the reflectance. The NIR reflectance of the coating on a standard white substrate with appropriate coating thickness and volume fraction was much higher than that on a standard black substrate. From the comparison between the experimental and calculated results, we know that more accurate particle size control enables us to achieve better performance. The use of appropriate particles with optimum size, coating thickness and volume fraction on a suitable substrate enables cool and black-color coating against solar irradiation. -- Highlights: • A new approach in designing pigmented coatings was used. • The effects of particles size on both visible and near infrared reflectivities were studied. • The results of numerical calculation were compared with experimental ones for CuO powders

Wave-induced ripple development in mixed clay-sand substrates

Science.gov (United States)

Wu, Xuxu; Parsons, Daniel; Baas, Jaco H.; Mouazé, Dominique; McLelland, Stuart; Amoudry, Laurent; Eggenhuisen, Jorris; Cartigny, Matthieu; Ruessink, Gerben

2016-04-01

This paper reports on a series of experiments that aim to provide a fuller understanding of ripple development within clay-sand mixture substrates under oscillatory flow conditions. The work was conducted in the Total Environment Simulator at the University of Hull and constituted 6 separate runs, in which 5 runs were conducted under identical sets of regular waves (an additional run was conducted under irregular waves, but is not discussed in present paper). The bed content was systematically varied in its composition ranging from a pure sand bed through to a bed comprising 7.4% clay. A series of state-of-the-art measurements were employed to quantify interactions of near-bed hydrodynamics, sediment transport, and turbulence over rippled beds formed by wave action, during and after, each run. The experimental results demonstrate the significant influence of the amount of cohesive clay materials in the substrate on ripple evolution under waves. Most importantly, addition of clay in the bed dramatically slowed down the rate of ripple development and evolution. The equilibrium time of each run increased exponentially from 30 minutes under the control conditions of a pure sand bed, rising to ~350 minutes for the bed with the highest fraction of clay. The paper discusses the slower ripple growth rates with higher cohesive fractions, via an influence on critical shear, but highlights that the end equilibrium size of ripples is found to be independent of increasing substrate clay fraction. The suspended particles mass (SPM) concentration indicates that clay particles were suspended and winnowed by wave action. Additionally, laser granulometry of the final substrates verified that ripple crests were composed of pure sand layers that were absent at ripple troughs, reflecting a relatively higher winnowing efficiency at wave ripples crest. The winnowing process and its efficiency is inexorably linked to wave ripple development and evolution. The implications of the results

Microstructure and wear behavior of laser cladding VC–Cr7C3 ceramic coating on steel substrate

International Nuclear Information System (INIS)

Wu, Qianlin; Li, Wenge; Zhong, Ning; Gang, Wu; Haishan, Wang

2013-01-01

Highlights: ► The VC–Cr 7 C 3 coating on steel substrate was in situ produced by laser cladding. ► The distribution of VC–Cr 7 C 3 phase decreased gradually from the top of the coating. ► The laser cladding achieved a high hardness of the order of 1000 HV. ► The wear resistance of the coating was 4 times that of the steel substrate. - Abstract: To enhance the wear resistance of mechanical components, laser cladding has been applied to deposit in situ VC–Cr 7 C 3 ceramic coating on steel substrate using a pre-placed powder consisting of vanadium, carbon and high-carbon ferrochrome. The laser cladding samples were subjected to various microstructure examinations, microhardness and wear tests. The results showed that defect-free coating with metallurgical joint to the steel substrate was obtained. The quantity of VC–Cr 7 C 3 particles gradually increased from the bottom to the top of the coating. The VC particles in nanometer were observed within the coating. Average hardness of the coating up to 1050 HV was significantly higher than that of the substrate 150 HV. Wear tests indicated the wear resistance of the clad coating was 4 times that of the steel substrate

Formation Process of Eosin Y-Adsorbing ZnO Particles by Electroless Deposition and Their Photoelectric Conversion Properties.

Science.gov (United States)

Nagaya, Satoshi; Nishikiori, Hiromasa; Mizusaki, Hideaki; Wagata, Hajime; Teshima, Katsuya

2015-06-03

The thin films consisting of crystalline ZnO particles were prepared on fluorine-doped tin oxide electrodes by electroless deposition. The particles were deposited from an aqueous solution containing zinc nitrate, dimethyamine-borane, and eosin Y at 328 K. As the Pd particles were adsorbed on the substrate, not only the eosin Y monomer but also the dimer and debrominated species were rapidly adsorbed on the spherical ZnO particles, which were aggregated and formed secondary particles. On the other hand, in the absence of the Pd particles, the monomer was adsorbed on the flake-shaped ZnO particles, which vertically grew on the substrate surface and had a high crystallinity. The photoelectric conversion efficiency was higher for the ZnO electrodes containing a higher amount of the monomer during light irradiation.

Nano/micro particle beam for ceramic deposition and mechanical etching

International Nuclear Information System (INIS)

Chun, Doo-Man; Kim, Min-Saeng; Kim, Min-Hyeng; Ahn, Sung-Hoon; Yeo, Jun-Cheol; Lee, Caroline Sunyong

2010-01-01

Nano/micro particle beam (NPB) is a newly developed ceramic deposition and mechanical etching process. Additive (deposition) and subtractive (mechanical etching) processes can be realized in one manufacturing process using ceramic nano/micro particles. Nano- or micro-sized powders are sprayed through the supersonic nozzle at room temperature and low vacuum conditions. According to the process conditions, the ceramic powder can be deposited on metal substrates without thermal damage, and mechanical etching can be conducted in the same process with a simple change of process conditions and powders. In the present work, ceramic aluminum oxide (Al 2 O 3 ) thin films were deposited on metal substrates. In addition, the glass substrate was etched using a mask to make small channels. Deposited and mechanically etched surface morphology, coating thickness and channel depth were investigated. The test results showed that the NPB provides a feasible additive and subtractive process using ceramic powders.

Effects of substrate pretreatments on diamond synthesis for Si{sub 3}N{sub 4} based ceramics

Energy Technology Data Exchange (ETDEWEB)

Shibuya, Y. [Prefectural Industrial Research Inst., Shizuoka (Japan); Takaya, M. [Chiba Institute of Technology, Tsudanuma 2-chome, Narashino-shi, 275 (Japan)

1998-07-08

Diamond synthesis for Si{sub 3}N{sub 4} ceramics after various substrate pretreatments has been carried out by the microwave-plasma enhanced chemical vapor deposition (CVD) method using a mixture of methane and hydrogen gases. Four types of pretreatments for various substrates were performed as follows: scratching with diamond powder (I), applying O{sub 2}-C{sub 2}H{sub 2} combustion flames (II), polishing with alumina (III), and platinum vapor deposition (IV). The products deposited on the substrate were examined with micro-Raman spectroscopy, scanning electron microscopy (SEM) and an X-ray diffractometer (XRD). It was found that the application of O{sub 2}-C{sub 2}H{sub 2} flames as a pretreatment of the substrate in diamond synthesis was suitable, because a higher density of diamond nucleation could be obtained, and a film-like diamond could be formed on the surface in a shorter time than without applying them. The diamond could be synthesized on the surface for all four types of substrate pretreatments performed in the present study. The effects of the substrate pretreatments on the surface morphology of grown diamond were that a film-like diamond for (I) or (II), a particle-like diamond for (III) and a particle and/or a film-like diamond for (IV) were formed on the surface. The surface morphology of grown diamond depended very much on the substrate temperature under deposition. (orig.) 18 refs.

Dewetting and spreading transitions for active matter on random pinning substrates.

Science.gov (United States)

Sándor, Cs; Libál, A; Reichhardt, C; Olson Reichhardt, C J

2017-05-28

We show that sterically interacting self-propelled disks in the presence of random pinning substrates exhibit transitions among a variety of different states. In particular, from a phase separated cluster state, the disks can spread out and homogeneously cover the substrate in what can be viewed as an example of an active matter wetting transition. We map the location of this transition as a function of activity, disk density, and substrate strength, and we also identify other phases including a cluster state, coexistence between a cluster and a labyrinth wetted phase, and a pinned liquid. Convenient measures of these phases include the cluster size, which dips at the wetting-dewetting transition, and the fraction of sixfold coordinated particles, which drops when dewetting occurs.

Silver Eco-Solvent Ink for Reactive Printing of Polychromatic SERS and SPR Substrates.

Science.gov (United States)

Dustov, Mavlavi; Golovina, Diana I; Polyakov, Alexander Yu; Goldt, Anastasia E; Eliseev, Andrei A; Kolesnikov, Efim A; Sukhorukova, Irina V; Shtansky, Dmitry V; Grünert, Wolfgang; Grigorieva, Anastasia V

2018-02-09

A new reactive ink based on a silver citrate complex is proposed for a photochemical route to surface-enhanced Raman spectroscopy active substrates with controllable extinction spectra. The drop-cast test of the ink reveals homogeneous nucleation of silver and colloid particle growth originating directly from photochemical in situ reduction in droplets, while the following evaporation of the deposited ink produces small nano- and micron-size particles. The prepared nanostructures and substrates were accurately characterized by electron microscopy methods and optical extinction spectroscopy. Varying the duration of UV irradiation allows tuning the morphology of individual silver nanoparticles forming hierarchical ring structures with numerous "hot spots" for most efficient Raman enhancement. Raman measurements of probe molecules of rhodamine 6G and methylene blue reached the largest signal enhancement of 10⁶ by the resonance effects.

Transport and selective chaining of bidisperse particles in a travelling wave potential.

Science.gov (United States)

Tierno, Pietro; Straube, Arthur V

2016-05-01

We combine experiments, theory and numerical simulation to investigate the dynamics of a binary suspension of paramagnetic colloidal particles dispersed in water and transported above a stripe-patterned magnetic garnet film. The substrate generates a one-dimensional periodic energy landscape above its surface. The application of an elliptically polarized rotating magnetic field causes the landscape to translate, inducing direct transport of paramagnetic particles placed above the film. The ellipticity of the applied field can be used to control and tune the interparticle interactions, from net repulsive to net attractive. When considering particles of two distinct sizes, we find that, depending on their elevation above the surface of the magnetic substrate, the particles feel effectively different potentials, resulting in different mobilities. We exploit this feature to induce selective chaining for certain values of the applied field parameters. In particular, when driving two types of particles, we force only one type to condense into travelling parallel chains. These chains confine the movement of the other non-chaining particles within narrow colloidal channels. This phenomenon is explained by considering the balance of pairwise magnetic forces between the particles and their individual coupling with the travelling landscape.

Transparent Conductive Adhesives for Tandem Solar Cells Using Polymer-Particle Composites

Energy Technology Data Exchange (ETDEWEB)

Klein, Talysa [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Lee, Benjamin G [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Schnabel, Manuel [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Warren, Emily L [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Stradins, Paul [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Tamboli, Adele C [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Van Hest, Marinus F [National Renewable Energy Laboratory (NREL), Golden, CO (United States)

2018-02-14

Transparent conductive adhesives (TCAs) can enable conductivity between two substrates, which is useful for a wide range of electronic devices. Here, we have developed a TCA composed of a polymer-particle blend with ethylene-vinyl acetate as the transparent adhesive and metal-coated flexible poly(methyl methacrylate) microspheres as the conductive particles that can provide conductivity and adhesion regardless of the surface texture. This TCA layer was designed to be nearly transparent, conductive in only the out-of-plane direction, and of practical adhesive strength to hold the substrates together. The series resistance was measured at 0.3 and 0.8 O cm2 for 8 and 0.2% particle coverage, respectively, while remaining over 92% was transparent in both cases. For applications in photovoltaic devices, such as mechanically stacked multijunction III-V/Si cells, a TCA with 1% particle coverage will have less than 0.5% power loss due to the resistance and less than 1% shading loss to the bottom cell.

Possible pitfalls in search of magnetic order in thin films deposited on single crystalline sapphire substrates

International Nuclear Information System (INIS)

Salzer, R.; Spemann, D.; Esquinazi, P.; Hoehne, R.; Setzer, A.; Schindler, K.; Schmidt, H.; Butz, T.

2007-01-01

We have studied the field and temperature dependence of the magnetic moment of single crystalline sapphire substrates with different surface orientations. All the substrates show a ferromagnetic behavior that partially changes after surface cleaning. The amount of magnetic impurities in the substrates was determined by particle induced X-ray emission. The overall analysis of the data indicates that the magnetic impurities very likely contribute to the measured ferromagnetic behavior but does not rule out completely intrinsic contributions. Our work stresses the necessity to use other than bulk characterization methods for the study of weak ferromagnetic signals of thin films grown on oxide substrates

An ALC study of spin exchange of a muoniated cosurfactant in lamellar phase surfactant dispersions

International Nuclear Information System (INIS)

Dilger, H.; Martyniak, A.; Scheuermann, R.; Vujosevic', D.; Tucker, I.M.; McKenzie, I.; Roduner, E.

2006-01-01

The Avoided Level Crossing muon spin resonance (ALC-μSR) technique has been used to measure the Heisenberg spin exchange rate between the Mu adducts of 2-phenylethanol (PEA) and Ni 2+ in a concentrated lamellar phase dispersion composed of the dichain cationic surfactant 2,3-diheptadecyl ester ethoxypropyl-1,1,1-trimethylammonium chloride (DHTAC) and water. Ni 2+ is only dissolved in the aqueous phase, therefore information about the local environment of the PEA can be extracted from the spin exchange rate. In the high-temperature (L α ) phase the spin exchange is very slow, revealing that PEA preferentially resides in the headgroup regime of the surfactant. In the low-temperature (L β ) phase the spin exchange is diffusion controlled, because the PEA is expelled into the water region between the bilayers

Grip and detachment of locusts on inverted sandpaper substrates

International Nuclear Information System (INIS)

Han Longbao; Wang Zhouyi; Ji Aihong; Dai Zhendong

2011-01-01

Locusts (Locusta migratoria manilensis) are characterized by their strong flying and grasping ability. Research on the grasping mechanism and behaviour of locusts on sloping substrates plays an important role in elucidating the mechanics of hexapod locomotion. Data on the maximum angles of slope at which locusts can grasp stably (critical angles of detachment) were obtained from high-speed video recordings at 215 fps. The grasping forces were collected by using two sensors, in situations where all left legs were standing on one and the right legs on the other sensor plate. These data were used to illustrate the grasping ability of locusts on slopes with varying levels of roughness. The grasping morphologies of locusts' bodies and tarsi were observed, and the surface roughness as well as diameters of their claw tips was measured under a microscope to account for the grasping mechanism of these insects on the sloping substrate. The results showed that the claw tips and part of the pads were in contact with the inverted substrate when the mean particle diameter was in the range of 15.3-40.5 μm. The interaction between pads and substrates may improve the stability of contact, and claw tips may play a key role in keeping the attachment reliable. A model was developed to explain the significant effects of the relative size of claw tips and mean particle diameter on grasping ability as well as the observed increase in lateral force (2.09-4.05 times greater than the normal force during detachment) with increasing slope angle, which indicates that the lateral force may be extremely important in keeping the contact reliable. This research lays the groundwork for the probable design and development of biomimetic robotics.

Tuneable nanoparticle-nanofiber composite substrate for improved cellular adhesion.

Science.gov (United States)

Nicolini, Ariana M; Toth, Tyler D; Yoon, Jeong-Yeol

2016-09-01

This work presents a novel technique using a reverse potential electrospinning mode for fabricating nanoparticle-embedded composites that can be tailored to represent various fiber diameters, surface morphologies, and functional groups necessary for improved cellular adhesion. Polycaprolactone (PCL) nanofibers were electrospun in both traditional positive (PP) and reverse potential (RP) electrical fields. The fibers were incorporated with 300nm polystyrene (PS) fluorescent particles, which contained carboxyl, amine groups, and surfactants. In the unconventional RP, the charged colloidal particles and surfactants were shown to have an exaggerated effect on Taylor cone morphology and fiber diameter caused by the changes in charge density and surface tension of the bulk solution. The RP mode was shown to lead to a decrease in fiber diameter from 1200±100nm (diameter±SE) for the nanofibers made with PCL alone to 440±80nm with the incorporation of colloidal particles, compared to the PP mode ranging from 530±90nm to 350±50nm, respectively. The nanoparticle-nanofiber composite substrates were cultured with human umbilical vein endothelial cells (HUVECs) and evaluated for cellular viability and adhesion for up to 5 days. Adhesion to the nanofibrous substrates was improved by 180±10% with the addition of carboxylated particles and by 480±60% with the functionalization of an RGD ligand compared to the PCL nanofibers. The novel approach of electrospinning in the RP mode with the addition of colloids in order to alter charge density and surface tension could be utilized towards many applications, one being implantable biomaterials and tissue engineered scaffolds as demonstrated in this work. Copyright © 2016 Elsevier B.V. All rights reserved.

Microstructure and bonding strength of Ni-based alloy coating

Directory of Open Access Journals (Sweden)

LIU Qing

2006-05-01

Full Text Available A Ni-Cr-B-Si coating technique was developed and successfully applied on austenite grey iron substrate in a conventional resistance furnace under graphite powder protection. The microstructure, phase distribution, chemical composition profile and microhardness along the coating layer depth were investigated. Shear strength of the coating was also tested. Microanalysis shows that the coating is consist of γ-Ni solution and γ-Ni+Ni3B lamellar eutectic, as well as small amount of Cr5B3 particles. Diffusion induced metallurgical bonding occurs at the coating/substrate interfaces, and the higher the temperature, the more sufficient elements diffused, the broader interfusion region and the larger bonding strength, but it has an optimum value. And the bonding strength at the interface can be enable to reach 250-270 MPa, which is nearly the same as that of processed by flame spray. The microhardness along the coating layer depth shows a gradient distribution manner.

Distributions of chain ends and junction points in ordered block copolymers

International Nuclear Information System (INIS)

Mayes, A.M.; Johnson, R.D.; Russell, T.P.; Smith, S.D.; Satija, S.K.; Majkrzak, C.F.

1993-01-01

Chain configurations in ordered symmetric poly(styrene-b-methyl methacrylate) diblock copolymers were examined by neutron reflectively. In a thin-film geometry the copolymers organize into lamellar microdomains oriented parallel to the substrate surface. The copolymers organize into lamellar microdomains oriented parallel to the substrate surface. The copolymers were synthesized with small fractions of deuterated segments at either the chain ends or centers. This selective labeling permitted characterization of the spatial distribution of chain ends and junction points normal to the plane of the film. From the reflectivity analysis, the junction points are found to be confined to the PS/PMMA interfacial regions. The chain ends, however, are well distributed through their respective domains, exhibiting only a weak maximum in concentration at the center of the domains

In-situ TEM investigations of graphic-epitaxy and small particles. Final Report, 1 January-31 December 1982

International Nuclear Information System (INIS)

Heinemann, K.

1983-01-01

Palladium was deposited inside a controlled-vacuum specimen chamber of a transmission electron microscope (TEM) onto MgO and alpha-alumina substrate surfaces. Annealing and various effects of gas exposure of the particulate Pd deposits were studied in-situ by high resolution TEM and electron diffraction. Whereas substrate temperatures of 500 C or annealing of room temperature (RT) deposits to 500 C were needed to obtain epitaxy on sapphire, RT deposits on MgO were perfectly epitaxial. For Pd/MgO a lattice expansion of 2 to 4% was noted the highest values of expansion were found for the smallest particles. The lattice expansion of small Pd particles on alumina substrates was less than 1%. Long-time RT exposure of Pd/MgO in a vacuum yielded some moblity and coalescence events, but notably fewer than for Pd on sapphire. Exposure to air or oxygen greatly enhanced the particle mobility and coalescence and also resulted in the flattening of Pd particles on MgO substrates. Electron-beam irradiation further enhanced this effect. Exposure to air for several tens of hours of Pd/MgO led to strong coalescence

Neutron spin-echo investigation of the microemulsion dynamics. in bicontinuous lamellar and droplet phases

CERN Document Server

Mihailescu, M; Endo, H; Allgaier, J; Gompper, G; Stellbrink, J; Richter, D; Jakobs, B; Sottmann, T; Faragó, B

2002-01-01

Using neutron spin-echo (NSE) spectroscopy in combination with dynamic light scattering (DLS), we performed an extensive investigation of the bicontinuous phase in ternary water-surfactant-oil microemulsions, with extension to lamellar and droplet phases. The dynamical behavior of surfactant monolayers of decyl-polyglycol-ether (C sub 1 sub 0 E sub 4) molecules, or mixtures of surfactant with long amphiphilic block-copolymers of type poly-ethylene propylene/poly-ethylene oxide (PEP-PEO) was studied, under comparable conditions. The investigation techniques provide access to different length scales relative to the characteristic periodicity length of the microemulsion structure. Information on the elastic bending modulus is obtained from the local scale dynamics in view of existing theoretical descriptions and is found to be in accordance with small angle neutron scattering (SANS) studies. Evidence for the modified elastic properties and additional interaction of the amphiphilic layers due to the polymer is mo...

Effects of substrate temperature, substrate orientation, and energetic atomic collisions on the structure of GaN films grown by reactive sputtering

Energy Technology Data Exchange (ETDEWEB)

Schiaber, Ziani S.; Lisboa-Filho, Paulo N.; Silva, José H. D. da [Universidade Estadual Paulista, UNESP, Bauru, São Paulo 17033-360 (Brazil); Leite, Douglas M. G. [Universidade Federal de Itajubá, UNIFEI, Itajubá, Minas Gerais 37500-903 (Brazil); Bortoleto, José R. R. [Universidade Estadual Paulista, UNESP, Sorocaba, São Paulo 18087-180 (Brazil)

2013-11-14

The combined effects of substrate temperature, substrate orientation, and energetic particle impingement on the structure of GaN films grown by reactive radio-frequency magnetron sputtering are investigated. Monte-Carlo based simulations are employed to analyze the energies of the species generated in the plasma and colliding with the growing surface. Polycrystalline films grown at temperatures ranging from 500 to 1000 °C clearly showed a dependence of orientation texture and surface morphology on substrate orientation (c- and a-plane sapphire) in which the (0001) GaN planes were parallel to the substrate surface. A large increase in interplanar spacing associated with the increase in both a- and c-parameters of the hexagonal lattice and a redshift of the optical bandgap were observed at substrate temperatures higher than 600 °C. The results showed that the tensile stresses produced during the film's growth in high-temperature deposition ranges were much larger than the expected compressive stresses caused by the difference in the thermal expansion coefficients of the film and substrate in the cool-down process after the film growth. The best films were deposited at 500 °C, 30 W and 600 °C, 45 W, which corresponds to conditions where the out diffusion from the film is low. Under these conditions the benefits of the temperature increase because of the decrease in defect density are greater than the problems caused by the strongly strained lattice that occurr at higher temperatures. The results are useful to the analysis of the growth conditions of GaN films by reactive sputtering.

Theoretical study of the interparticle interaction of nanoparticles randomly dispersed on a substrate

International Nuclear Information System (INIS)

Horikoshi, S.; Kato, T.

2015-01-01

Metal nanoparticles exhibit the phenomenon of localized surface plasmon resonance (LSPR) due to the collective oscillation of their conduction electrons, which is induced by external electromagnetic radiation. The finite-differential time-domain (FDTD) method is widely used as an electromagnetic field analysis tool for nanoparticles. Although the influence of interparticle interactions is taken into consideration in the FDTD calculation for the plural particles configuration, the FDTD calculation of a random configuration is very difficult, particularly in the case of non-spherical particles. In this study, a theoretical calculation method incorporating interparticle interactions on a substrate with various particle shapes and sizes on a subwavelength scale is developed. The interparticle interaction is incorporated following FDTD calculation with an isolated single particle. This is explained systematically using a signal flow graph. Moreover, the mirror image effect of the substrate and the retardation effect are also taken into account in this method. The validity of this method is verified by calculations for simple arrangements of nanoparticles. In addition, it is confirmed that the method can improve the accuracy of predicted experimental results for Au nanoparticles prepared by the sputtering method, in terms of the plasmon peak wavelength. This method may enable the design of LSPR devices by controlling nanoparticle characteristics, such as the size, shape, and distribution density

Flux Growth of Highly Crystalline Photocatalytic BaTiO3 Particle Layers on Porous Titanium Sponge Substrate and Insights into the Formation Mechanism

Science.gov (United States)

Wang, Q.; Li, B.

2017-09-01

A unique architecture of idiomorphic and highly crystalline BaTiO3 particle layers directly grown on a porous titanium sponge substrate was successfully achieved for the first time using a facile molten salt method at a relatively low temperature of 700 °C. Specifically, the low-melting KCl-NaCl eutectic salts and barium hydroxide octahydrate were employed as the reaction medium and barium source, respectively. Powder X-ray diffraction (XRD), scanning electron microscopy (SEM), Energy dispersive X-ray spectroscopy (EDS), transmission electron microscopy (TEM), high-resolution transmission electron microscopy (HRTEM) and UV-vis diffuse reflectance spectrophotometry were used to characterize the structure, morphology and optical property of the obtained samples. The results revealed that the flux-grown tetragonal BaTiO3 products had well-defined and uniform morphology with an average size of 300 nm and a band gap of ∼3.16 eV. Based on XRD, EDS, SEM, and TEM, the possible formation mechanism responsible for the well-developed architecture of BaTiO3 particle layers was proposed and discussed. Furthermore, the photocatalytic activity of the flux-grown BaTiO3 products for organic pollutant degradation under simulated sunlight irradiation was also investigated.

Chlorine-containing salts as water ice nucleating particles on Mars

Science.gov (United States)

Santiago-Materese, D. L.; Iraci, L. T.; Clapham, M. E.; Chuang, P. Y.

2018-03-01

Water ice cloud formation on Mars largely is expected to occur on the most efficient ice nucleating particle available. Salts have been observed on the Martian surface and have been known to facilitate water cloud formation on Earth. We examined heterogeneous ice nucleation onto sodium chloride and sodium perchlorate substrates under Martian atmospheric conditions, in the range of 150 to 180 K and 10-7 to 10-5 Torr water partial pressure. Sub-155 K data for the critical saturation ratio (Scrit) suggests an exponential model best describes the temperature-dependence of nucleation onset of water ice for all substrates tested. While sodium chloride does not facilitate water ice nucleation more easily than bare silicon, sodium perchlorate does support depositional nucleation at lower saturation levels than other substrates shown and is comparable to smectite-rich clay in its ability to support cloud initiation. Perchlorates could nucleate water ice at partial pressures up to 40% lower than other substrates examined to date under Martian atmospheric conditions. These findings suggest air masses on Mars containing uplifted salts such as perchlorates could form water ice clouds at lower saturation ratios than in air masses absent similar particles.

Substrate-mediated enhanced activity of Ru nanoparticles in catalytic hydrogenation of benzene

KAUST Repository

Liu, Xin

2012-01-01

The impact of carbon substrate-Ru nanoparticle interactions on benzene and hydrogen adsorption that is directly related to the performance in catalytic hydrogenation of benzene has been investigated by first-principles based calculations. The stability of Ru 13 nanoparticles is enhanced by the defective graphene substrate due to the hybridization between the dsp states of the Ru 13 particle with the sp 2 dangling bonds at the defect sites. The local curvature formed at the interface will also raise the Ru atomic diffusion barrier, and prohibit the particle sintering. The strong interfacial interaction results in the shift of averaged d-band center of the deposited Ru nanoparticle, from -1.41 eV for a freestanding Ru 13 particle, to -1.17 eV for the Ru/Graphene composites, and to -1.54 eV on mesocellular foam carbon. Accordingly, the adsorption energies of benzene are increased from -2.53 eV for the Ru/mesocellular foam carbon composites, to -2.62 eV on freestanding Ru 13 particles, to -2.74 eV on Ru/graphene composites. A similar change in hydrogen adsorption is also observed, and all these can be correlated to the shift of the d-band center of the nanoparticle. Thus, Ru nanoparticles graphene composites are expected to exhibit both high stability and superior catalytic performance in hydrogenation of arenes. © 2012 The Royal Society of Chemistry.

High resolution microstructure characterization of the interface between cold sprayed Al coating and Mg alloy substrate

International Nuclear Information System (INIS)

Wang, Qiang; Qiu, Dong; Xiong, Yuming; Birbilis, Nick; Zhang, Ming-Xing

2014-01-01

High-resolution transmission electron microscopy (HR-TEM) has validated the intimate metallurgical (atomic) bond formed along the interface of a cold-sprayed Al coating upon an Mg-alloy (AZ91) substrate. The compressive impact led to the formation of nanostructured layers of about 300–500 nm into the substrate. A highly distorted lattice structure with the inclusion of small amorphous zones was observed at the periphery of the particle/substrate interface, as a result of adiabatic shear plastic deformation at a high strain rate.

Particle formation and its control in dual frequency plasma etching reactors

International Nuclear Information System (INIS)

Kim, Munsu; Cheong, Hee-Woon; Whang, Ki-Woong

2015-01-01

The behavior of a particle cloud in plasma etching reactors at the moment when radio frequency (RF) power changes, that is, turning off and transition steps, was observed using the laser-light-scattering method. Two types of reactors, dual-frequency capacitively coupled plasma (CCP) and the hybrid CCP/inductively coupled plasma (ICP), were set up for experiments. In the hybrid CCP/ICP reactor (hereafter ICP reactor), the position and shape of the cloud were strongly dependent on the RF frequency. The particle cloud becomes larger and approaches the electrode as the RF frequency increases. By turning the lower frequency power off later with a small delay time, the particle cloud is made to move away from the electrode. Maintaining lower frequency RF power only was also helpful to reduce the particle cloud size during this transition step. In the ICP reactor, a sufficient bias power is necessary to make a particle trap appear. A similar particle cloud to that in the CCP reactor was observed around the sheath region of the lower electrode. The authors can also use the low-frequency effect to move the particle cloud away from the substrate holder if two or more bias powers are applied to the substrate holder. The dependence of the particle behavior on the RF frequencies suggests that choosing the proper frequency at the right moment during RF power changes can reduce particle contamination effectively

Adhesion enhancement of diamond-like carbon thin films on Ti alloys by incorporation of nanodiamond particles

International Nuclear Information System (INIS)

Zhang, C.Z.; Tang, Y.; Li, Y.S.; Yang, Q.

2013-01-01

Coating adherent diamond-like carbon (DLC) thin films directly on Ti alloys is technologically difficult. This research incorporates nanodiamond particles to form a diamond/DLC composite interlayer to enhance the adhesion of DLC thin films on Ti6Al4V substrates. Initially, nanodiamond particles were deposited on Ti6Al4V substrates by microwave plasma enhanced chemical vapor deposition from a methane–hydrogen gas mixture. A DLC thin film was then deposited, on top of the nanodiamond particles, by direct ion beam deposition. Scanning electron microscopy, Atomic force microscopy, X-ray Diffraction and Raman spectroscopy were used to characterize the microstructure and chemical bonding of the deposited particles and films, and Rockwell indentation testing was used to evaluate the adhesion of the deposited films. The results indicate that the pre-deposited nanodiamond particles significantly enhance the interfacial adhesion between the DLC thin film and the Ti6Al4V substrate, possibly by enhanced interfacial bonding, mechanical interlocking, and stress relief. - Highlights: ► Nanodiamond particles were deposited on Ti6Al4V before DLC deposition. ► Diamond/DLC composite film was formed by incorporation of nanodiamond particles. ► Greatly enhanced adhesion of diamond/DLC composite film on Ti6Al4V was achieved. ► Enhanced adhesion is by increased interfacial bonding and mechanical interlocking

Adhesion enhancement of diamond-like carbon thin films on Ti alloys by incorporation of nanodiamond particles

Energy Technology Data Exchange (ETDEWEB)

Zhang, C.Z.; Tang, Y. [Department of Mechanical Engineering, University of Saskatchewan, 57 Campus Drive, Saskatoon, SK, Canada S7N 5A9 (Canada); Li, Y.S. [Plasma Physics Laboratory, University of Saskatchewan, 116 Science Place, Saskatoon, SK, Canada S7N 5E2 (Canada); Yang, Q., E-mail: qiaoqin.yang@usask.ca [Department of Mechanical Engineering, University of Saskatchewan, 57 Campus Drive, Saskatoon, SK, Canada S7N 5A9 (Canada)

2013-01-01

Coating adherent diamond-like carbon (DLC) thin films directly on Ti alloys is technologically difficult. This research incorporates nanodiamond particles to form a diamond/DLC composite interlayer to enhance the adhesion of DLC thin films on Ti6Al4V substrates. Initially, nanodiamond particles were deposited on Ti6Al4V substrates by microwave plasma enhanced chemical vapor deposition from a methane–hydrogen gas mixture. A DLC thin film was then deposited, on top of the nanodiamond particles, by direct ion beam deposition. Scanning electron microscopy, Atomic force microscopy, X-ray Diffraction and Raman spectroscopy were used to characterize the microstructure and chemical bonding of the deposited particles and films, and Rockwell indentation testing was used to evaluate the adhesion of the deposited films. The results indicate that the pre-deposited nanodiamond particles significantly enhance the interfacial adhesion between the DLC thin film and the Ti6Al4V substrate, possibly by enhanced interfacial bonding, mechanical interlocking, and stress relief. - Highlights: ► Nanodiamond particles were deposited on Ti6Al4V before DLC deposition. ► Diamond/DLC composite film was formed by incorporation of nanodiamond particles. ► Greatly enhanced adhesion of diamond/DLC composite film on Ti6Al4V was achieved. ► Enhanced adhesion is by increased interfacial bonding and mechanical interlocking.

Substrate-mediated enhanced activity of Ru nanoparticles in catalytic hydrogenation of benzene

KAUST Repository

Liu, Xin; Meng, Changgong; Han, Yu

2012-01-01

. The stability of Ru 13 nanoparticles is enhanced by the defective graphene substrate due to the hybridization between the dsp states of the Ru 13 particle with the sp 2 dangling bonds at the defect sites. The local curvature formed at the interface will also

Evaluation of preparation methods for suspended nano-objects on substrates for dimensional measurements by atomic force microscopy

OpenAIRE

Fiala, Petra; G?hler, Daniel; Wessely, Benno; Stintz, Michael; Lazzerini, Giovanni Mattia; Yacoot, Andrew

2017-01-01

Dimensional measurements on nano-objects by atomic force microscopy (AFM) require samples of safely fixed and well individualized particles with a suitable surface-specific particle number on flat and clean substrates. Several known and proven particle preparation methods, i.e., membrane filtration, drying, rinsing, dip coating as well as electrostatic and thermal precipitation, were performed by means of scanning electron microscopy to examine their suitability for preparing samples for dime...

An ALC study of spin exchange of a muoniated cosurfactant in lamellar phase surfactant dispersions

Energy Technology Data Exchange (ETDEWEB)

Dilger, H. [Institute of Physical Chemistry, University of Stuttgart, Pfaffenwaldring 55, D-70569 Stuttgart (Germany)]. E-mail: h.dilger@ipc.uni-stuttgart.de; Martyniak, A. [Institute of Physical Chemistry, University of Stuttgart, Pfaffenwaldring 55, D-70569 Stuttgart (Germany); Scheuermann, R. [Laboratory for Muon Spin Spectroscopy, Paul Scherrer Institut, CH-5232 Villigen PSI (Switzerland); Vujosevic' , D. [Institute of Physical Chemistry, University of Stuttgart, Pfaffenwaldring 55, D-70569 Stuttgart (Germany); Tucker, I.M. [Unilever Research and Development, Port Sunlight, Wirral, CH63 3JW (United Kingdom); McKenzie, I. [Institute of Physical Chemistry, University of Stuttgart, Pfaffenwaldring 55, D-70569 Stuttgart (Germany); Roduner, E. [Institute of Physical Chemistry, University of Stuttgart, Pfaffenwaldring 55, D-70569 Stuttgart (Germany)

2006-03-31

The Avoided Level Crossing muon spin resonance (ALC-{mu}SR) technique has been used to measure the Heisenberg spin exchange rate between the Mu adducts of 2-phenylethanol (PEA) and Ni{sup 2+} in a concentrated lamellar phase dispersion composed of the dichain cationic surfactant 2,3-diheptadecyl ester ethoxypropyl-1,1,1-trimethylammonium chloride (DHTAC) and water. Ni{sup 2+} is only dissolved in the aqueous phase, therefore information about the local environment of the PEA can be extracted from the spin exchange rate. In the high-temperature (L{sub {alpha}}) phase the spin exchange is very slow, revealing that PEA preferentially resides in the headgroup regime of the surfactant. In the low-temperature (L{sub {beta}}) phase the spin exchange is diffusion controlled, because the PEA is expelled into the water region between the bilayers.

Toward an equilibrium structure in lamellar diblock copolymer thin films using solvent vapor annealing

DEFF Research Database (Denmark)

Sepe, Alessandro; Zhang, Jianqi; Perlich, Jan

2016-01-01

Solvent vapor annealing (SVA) is frequently used to improve the ordering in diblock copolymer thin films. An important question is which SVA protocol should be chosen to ensure thermodynamic equilibrium. Here, we investigate two thin films from a low molar-mass, lamellae-forming polystyrene....... SVA cycles were carried out with cyclohexane, and the structural changes were followed in-situ using time-resolved grazing-incidence small-angle X-ray scattering (GISAXS). Before and after SVA, Dlam,par is significantly lower than in the bulk, i.e. the equi-librium value of Dlam,par in thin film...... glassy again, affinely. During the second SVA cycle on the thin film, the scaling behavior of the lamellar thickness is identical to the one during the first drying and to the drying behavior of the thicker film. We conclude that one cycle of solvent vapor treatment with a degree of swelling of ca. 1...

The structure of a lipid-water lamellar phase containing two types of lipid monolayers

International Nuclear Information System (INIS)

Ranck, J.L.; Luzzati, V.; Zaccai, G.

1980-01-01

One lamellar phase, observed in the mitochondrial lipids-water system at low temperature (ca 253 K) and at low water content (ca 15%), contains four lipid monolayers in its unit cell, two of type α and two of type β. Previous X-ray scattering studies of this phase led to an ambiguity: the phase could contain either two homogeneous bilayers, one α and one β, or two mixed bilayers, each formed by an α and a β monolayer. A solution to this problem was sought in a neutron scattering study as a function of the D 2 O/H 2 O ratio. Because of limited resolution, straightforward analysis of the neutron scattering data leads also to ambiguous results. Using a more sophisticated analysis based upon the zeroth- and second-order moments of the Patterson peaks relevant to the exchangeable components, it is shown that the weight of the evidence is in favour of a structure containing mixed bilayers. (Auth.)

Marangoni Convection in Evaporating Organic Liquid Droplets on a Nonwetting Substrate.

Science.gov (United States)

Chandramohan, Aditya; Dash, Susmita; Weibel, Justin A; Chen, Xuemei; Garimella, Suresh V

2016-05-17

We quantitatively characterize the flow field inside organic liquid droplets evaporating on a nonwetting substrate. A mushroom-structured surface yields the desired nonwetting behavior with methanol droplets, while use of a cooled substrate (5-15 °C) slows the rate of evaporation to allow quasi-static particle image velocimetry. Visualization reveals a toroidal vortex within the droplet that is characteristic of surface tension-driven flow; we demonstrate by means of a scaling analysis that this recirculating flow is Marangoni convection. The velocities in the droplet are on the order of 10-45 mm/s. Thus, unlike in the case of evaporation on wetting substrates where Marangoni convection can be ignored for the purpose of estimating the evaporation rate, advection due to the surface tension-driven flow plays a dominant role in the heat transfer within an evaporating droplet on a nonwetting substrate because of the large height-to-radius aspect ratio of the droplet. We formulate a reduced-order model that includes advective transport within the droplet for prediction of organic liquid droplet evaporation on a nonwetting substrate and confirm that the predicted temperature differential across the height of the droplet matches experiments.

Substrate Effect on Carbon/Ceramic Mixed Matrix Membrane Prepared by a Vacuum-Assisted Method for Desalination

Directory of Open Access Journals (Sweden)

Yingjun Song

2018-05-01

Full Text Available This work investigates the effect of various membrane substrates and coating conditions on the formation of carbon/ceramic mixed matrix membranes for desalination application. The substrates were impregnated with phenolic resin via a vacuum-assisted method followed by carbonization under an inert gas. Substrates with pore sizes of 100 nm required a single impregnation step only, where short vacuum times (<120 s resulted in low quality membranes with defects. For vacuum times of ≥120 s, high quality membranes with homogeneous impregnation were prepared leading to high salt rejection (>90% and high water fluxes (up to 25 L m−2 h−1. The increase in water flux as a function of the vacuum time confirms the vacuum etching effect resulting from the vacuum-assisted method. Substrates with pore sizes of 140 nm required two impregnation steps. These pores were too large for the ceramic inter-particle space to be filled with phenolic resin via a single step. In the second impregnation step, increasing the concentration of the phenolic resin resulted in membranes with lower water fluxes. These results indicate that thicker films were formed by increasing the phenolic resin concentration. In the case of substrates with pores of 600 nm, these pores were too large and inter-particle space filling with phenolic resin was not attained.

Linear low density polyethylene (LLDPE) and lamellar zirconium phosphate (Zr P) composites: morphology and mechanical properties

International Nuclear Information System (INIS)

Silva, Daniela F.; Mandes, Luis C.; Lino, Adan S.

2011-01-01

Composites of linear low density polyethylene (LLDPE) and zirconium phosphate (ZrP) were prepared by extrusion in the molten state, containing 2 (w%) of the lamellar filler. The filler was previously synthesized by direct precipitation method and characterized. After processing, the composite and the pure virgin polymer were molded by compression in order to obtain films of 1 mm thick which were characterized by X-ray diffraction at high angle (WAXD), stress-strain mechanical analysis and scanning electron microscopy (SEM). The WAXD and SEM analysis showed that there was no intercalation of LLDPE in zirconium phosphate, possibly due to the fact that the layers do not have spacing enough to allow the intercalation of polymer chains in the galleries of the filler and thus allow the exfoliation. (author)

Molecular Dynamics Study on Nucleation Behavior and Lamellar Mergence of Polyethylene Globule Crystallization

Science.gov (United States)

Yang, Xiaozhen; Wang, Simiao

2012-02-01

The site order parameter (SOP) has been adopted to analyze various order structure formation and distribution during the crystallization of a multi-chain polyethylene globule simulated by molecular dynamics. We found that the nucleation relies on crystallinity fluctuation with increase of amplitude, and the baby nucleus in the fluctuation suddenly appears with different shape and increasing size. In the growth stage, a number of lamellar mergence was observed and their selective behaviors were suggested to be related to the orientation difference between the merging lamellae. We obtained that SOP distribution of all atoms in the system during crystallization appears with two peaks: one for the amorphous phase and the other for the crystalline phase. Mesomorphic structures with medium orders locate between the two peaks as an order promotion pathway. Obtained data show that the medium order structure fluctuates at the growth front and does not always be available; the medium order structure existing at the front is not always good for developing. It is possibly caused by chain entanglement.

Bilateral diffuse lamellar keratitis triggered by permanent eyeliner tattoo treatment: A case report.

Science.gov (United States)

Lu, Cheng-Wei; Liu, Xiu-Fen; Zhou, Dan-Dan; Kong, Yu-Jiao; Qi, Xiao-Feng; Liu, Tao-Tao; Qu, Ting; Pan, Xiao-Tao; Liu, Cong; Hao, Ji-Long

2017-07-01

Diffuse lamellar keratitis (DLK) is a sterile inflammation of the cornea, which may occur after laser-assisted in situ keratomileusis (LASIK) surgery. Little is known about the association of DLK with permanent eyeliner tattoo. The present case report describes the case of a 37-year-old Chinese woman who developed severe foreign body sensation in both eyes 1 week after receiving bilateral permanent eyeliner tattoo treatment. The patient had received bilateral LASIK surgery 10 years previously. Slit-lamp biomicroscopy revealed diffused granular infiltrates precipitated around the edge of the corneal flaps in both eyes. After topical treatment, DLK persisted. Therefore, the patient underwent surgery to remove the corneal epithelium around the DLK lesion. There was no recurrence of the disease during the 3-month observation period. To our knowledge, this is the first case report describing a case of late-onset of DLK that was triggered by permanent eyeliner tattoo. Doctors should be aware of the diagnosis and treatment of this complication associated with the application of permanent eyeliner tattoo as the popularity of this cosmetic procedure increases.

Hot gas path component cooling system having a particle collection chamber

Science.gov (United States)

Miranda, Carlos Miguel; Lacy, Benjamin Paul

2018-02-20

A cooling system for a hot gas path component includes a substrate having an outer surface and an inner surface. The inner surface defines at least one interior space. A passage is formed in the substrate between the outer surface and the inner surface. An access passage is formed in the substrate and extends from the outer surface to the inner space. The access passage is formed at a first acute angle to the passage and includes a particle collection chamber. The access passage is configured to channel a cooling fluid to the passage. Furthermore, the passage is configured to channel the cooling fluid therethrough to cool the substrate.

SiO2-supported Pt particles studied by electron microscopy

International Nuclear Information System (INIS)

Wang, D.; Penner, S.; Su, D.S.; Rupprechter, G.; Hayek, K.; Schloegl, R.

2003-01-01

Regularly grown Pt particles supported by amorphous SiO 2 were heated in hydrogen at 873 K after an oxidising treatment. The morphological and structural changes were studied by electron microscopy. Platinum silicides Pt 3 Si with L1 2 (Cu 3 Au) structure, monoclinic Pt 3 Si and tetragonal Pt 12 Si 5 were identified after the treatment. The mechanisms of coalescence of the particles and the formation of irregular large particles are suggested. A topotactic structural transformation accompanied with the migration of Si from the substrate to the particles are suggested to take place during Pt 3 Si formation

Light-Directed Particle Patterning by Evaporative Optical Marangoni Assembly.

Science.gov (United States)

Varanakkottu, Subramanyan Namboodiri; Anyfantakis, Manos; Morel, Mathieu; Rudiuk, Sergii; Baigl, Damien

2016-01-13

Controlled particle deposition on surfaces is crucial for both exploiting collective properties of particles and their integration into devices. Most available methods depend on intrinsic properties of either the substrate or the particles to be deposited making them difficult to apply to complex, naturally occurring or industrial formulations. Here we describe a new strategy to pattern particles from an evaporating drop, regardless of inherent particle characteristics and suspension composition. We use light to generate Marangoni surface stresses resulting in flow patterns that accumulate particles at predefined positions. Using projected images, we generate a broad variety of complex patterns, including multiple spots, lines and letters. Strikingly, this method, which we call evaporative optical Marangoni assembly (eOMA), allows us to pattern particles regardless of their size or surface properties, in model suspensions as well as in complex, real-world formulations such as commercial coffee.

Lovastatin Production by Aspergillus terreus Using Agro-Biomass as Substrate in Solid State Fermentation

Science.gov (United States)

Faseleh Jahromi, Mohammad; Liang, Juan Boo; Ho, Yin Wan; Mohamad, Rosfarizan; Goh, Yong Meng; Shokryazdan, Parisa

2012-01-01

Ability of two strains of Aspergillus terreus (ATCC 74135 and ATCC 20542) for production of lovastatin in solid state fermentation (SSF) using rice straw (RS) and oil palm frond (OPF) was investigated. Results showed that RS is a better substrate for production of lovastatin in SSF. Maximum production of lovastatin has been obtained using A. terreus ATCC 74135 and RS as substrate without additional nitrogen source (157.07 mg/kg dry matter (DM)). Although additional nitrogen source has no benefit effect on enhancing the lovastatin production using RS substrate, it improved the lovastatin production using OPF with maximum production of 70.17 and 63.76 mg/kg DM for A. terreus ATCC 20542 and A. terreus ATCC 74135, respectively (soybean meal as nitrogen source). Incubation temperature, moisture content, and particle size had shown significant effect on lovastatin production (P production (P > 0.05). Results also have shown that pH 6, 25°C incubation temperature, 1.4 to 2 mm particle size, 50% initial moisture content, and 8 days fermentation time are the best conditions for lovastatin production in SSF. Maximum production of lovastatin using optimized condition was 175.85 and 260.85 mg/kg DM for A. terreus ATCC 20542 and ATCC 74135, respectively, using RS as substrate. PMID:23118499

Y{sub 2}O{sub 3}: Eu{sup 3+}, Tb{sup 3+} spherical particles based anti-reflection and wavelength conversion bi-functional films: Synthesis and application to solar cells

Energy Technology Data Exchange (ETDEWEB)

Miao, Hui [School of Physics, Northwest University, Xi’an 710069 (China); National Photoelectric Technology and Functional Materials & Application of Science and Technology International Cooperation Base, Northwest University, Xi’an 710069 (China); Ji, Ruonan [School of Physics, Northwest University, Xi’an 710069 (China); Hu, Xiaoyun, E-mail: hxy3275@nwu.edu.cn [School of Physics, Northwest University, Xi’an 710069 (China); National Photoelectric Technology and Functional Materials & Application of Science and Technology International Cooperation Base, Northwest University, Xi’an 710069 (China); Han, Linzi; Hao, Yuanyuan; Sun, Qian [School of Physics, Northwest University, Xi’an 710069 (China); Zhang, Dekai [School of Physics, Northwest University, Xi’an 710069 (China); National Photoelectric Technology and Functional Materials & Application of Science and Technology International Cooperation Base, Northwest University, Xi’an 710069 (China); Fan, Jun [School of Chemical Engineering, Northwest University, Xi’an 710069 (China); Bai, Jintao [School of Physics, Northwest University, Xi’an 710069 (China); National Photoelectric Technology and Functional Materials & Application of Science and Technology International Cooperation Base, Northwest University, Xi’an 710069 (China); and others

2015-04-25

Highlights: • Eu{sup 3+} and Tb{sup 3+} co-doped Y{sub 2}O{sub 3} particles were successfully prepared. The as prepared particles can convert UV region photos to visible photons between 460 nm and 640 nm, which just matched the spectral response of most solar cells. • Y{sub 2}O{sub 3} is not only a good photoluminescence host material, but also it has high corrosion resistivity, thermal stability, and transparency from violet to infrared light. Cooperated with SiO{sub 2} sols, it could realize a better anti-reflection property. • As a proof-of-concept application, the as prepared bi-functional films could effectively improve the photoelectric conversion efficiency by 0.23% compared to pure SiO{sub 2} AR coating film and 0.55% compared to glass. - Abstract: In this study, Eu{sup 3+} and Tb{sup 3+} co-doped Y{sub 2}O{sub 3} particles were prepared via the simple, cost-effective urea homogeneous precipitation method without additives. The chosen particles were added in the SiO{sub 2} sols to get anti-reflection (AR) and wavelength conversion bi-functional films. Careful investigations were carried out to find the optimum preparation conditions and proper morphology. SEM images showed that the particle sizes reduced as metal ion/urea ratio decreased. Additionally, the extracted particles turned from sphere to lamellar type when the deionized water, which was used as solvent, reduced to a certain extent. The mechanisms of the morphology formation and diversification were proposed as well. The as prepared materials can convert UV region photos to visible photons between 460 nm and 640 nm, which just matched the spectral response of most solar cells. The spherical sample showed better luminescence performance than the one with lamellar morphology. In addition, the optical transmittance spectra indicated that the films adding spherical particles had better anti-reflective performance, and the best adding amount was 0.08 g. Finally, As a proof-of-concept application

An ingenious design of lamellar Li1.2Mn0.54Ni0.13Co0.13O2 hollow nanosphere cathode for advanced lithium-ion batteries

International Nuclear Information System (INIS)

Zhang, Yao; Zhang, Wansen; Shen, Shuiyun; Yan, Xiaohui; Wu, Aiming; Wu, Ruofei; Zhang, Junliang

2017-01-01

Highlights: •Lamellar Li 1.2 Mn 0.54 Ni 0.13 Co 0.13 O 2 hollow nanospheres serve as a cathode for LIBs. •Unique lamella and hollow structures benefit the enhanced electrochemical performance. •Lamellar shells can provide a short lithium-ion diffusion pathway. •The sufficient void space can accommodate volumetric expansion and contraction. -- Abstract: Although very appealing in developing hollow structured lithium-rich layered transition-metal oxides as cathodes for lithium-ion batteries (LIBs), a great challenge lies in controlling the growth of transition metal elements with desired molar ratios while maintaining intact hollow structures during synthesis. Herein, we propose a scalable strategy to successfully synthesize novel lamellar Li 1.2 Mn 0.54 Ni 0.13 Co 0.13 O 2 hollow (L-LMOH) nanosphere cathode for advanced lithium-ion batteries (LIBs). It is proved that the employment of sulfonated polystyrene (SPS) gel nanospheres as the template plays a key role in the formation of flower-like SPS@ Ni-Co-Mn-precursor nanospheres with desired molar ratios, and a subsequently delicate control in the heating rate leads to the intact L-LMOH nanospheres. It is demonstrated that the use of L-LMOH nanosphere cathode not only delivers outstanding reversible discharge capacities of 281.7 mAh g −1 at a current density of 20 mA g −1 and 136.6 mAh g −1 at 2000 mA g −1 , but also possess superior cycling stability with a capacity reservation of 80% at 2000 mA g −1 after 200 continuous cycles. It is well analyzed that the ingenious design of both unique lamella and hollow architectures synergistically benefits the significantly enhanced rate capability and cycling stability.

Creation of hydrophobic surfaces using a paint containing functionalized oxide particles

Science.gov (United States)

Sino, Paul Albert L.; Herrera, Marvin U.; Balela, Mary Donnabelle L.

2017-05-01

Hydrophobic surfaces were created by coating various substrates (aluminum sheet, soda-lime glass, silicon carbide polishing paper, glass with double-sided adhesive) with paint containing functionalized oxide particles. The paint was created by functionalizing oxide particles (ground ZnO, TiO2 nanoparticles, or TiO2 microparticles) with fluorosilane molecules in absolute ethanol. Water contact angle of samples shows that the coated substrate becomes hydrophobic (water contact angle ≥ 90°). Among the oxides that were used, ground ZnO yielded contact angle exemplifying superhydrophobicity (water contact angle ≥ 150°). Scanning electron micrograph of paint-containing TiO2 nanoparticles shows rough functionalized oxides structures which probably increase the hydrophobicity of the surface.

Modeling and simulation of deformation and fracture behavior of components made of fully lamellar {gamma}TiAl alloy

Energy Technology Data Exchange (ETDEWEB)

Kabir, Mohammad Rizviul [GKSS-Forschungszentrum Geesthacht GmbH (Germany). Inst. fuer Materialforschung

2008-07-01

The present work deals with the modeling and simulation of deformation and fracture behavior of fully lamellar {gamma}TiAl alloy; focusing on understanding the variability of local material properties and their influences on translamellar fracture. Afracture model has been presented that takes the inhomogeneity of the local deformation behavior of the lamellar colonies as well as the variability in fracture strength and toughness into consideration. To obtain the necessary model parameters, a hybrid methodology of experiments and simulations has been adopted. The experiments were performed at room temperature that demonstrates quasi-brittle response of the TiAl polycrystal. Aremarkable variation in stress-strain curves has been found in the tensile tests. Additional fracture tests showed significant variations in crack initiation and propagation during translamellar fracture. Analyzing the fracture surfaces, the micromechanical causes of these macroscopic scatter have been explained. The investigation shows that the global scatter in deformation and fracture response is highly influenced by the colony orientation and tilting angle with respect to the loading axis. The deformation and fracture behavior have been simulated by a finite element model including the material decohesion process described by a cohesive model. In order to capture the scatter of the macroscopic behavior, a stochastic approach is chosen. The local variability of stressstrain in the polycrystal and the variability of fracture parameters of the colonies are implemented in the stochastic approach of the cohesive model. It has been shown that the proposed approach is able to predict the stochastic nature of crack initiation and propagation as observed from the experiments. The global specimen failure with stable or unstable crack propagation can be explained in terms of the local variation of material properties. (orig.)

DNA hosted and aligned in aqueous interstitia of a lamellar liquid crystal – a membrane–biomacromolecule interaction model system

KAUST Repository

Carlsson, Nils; Jonsson, Fabian; Wilhelmsson, L. Marcus; Nordé n, Bengt; Å kerman, Bjö rn

2013-01-01

We report that DNA molecules can be intercalated and macroscopically oriented in the aqueous interstitia of a lyotropic lamellar liquid crystal. Using UV-vis linear dichroism and fluorescence spectroscopy we show that double-stranded oligonucleotides (25 base pairs) in the water-octanoate-decanol system remain base-paired in the B conformation and are confined in two dimensions, with the helix axis preferentially parallel to the lipid bilayer surfaces but free to rotate within this plane. The degree of helix confinement and the corresponding 2-D orientation can be improved by decreasing the thickness of the water interstitia via the fraction of water in the ternary mixture. Not surprisingly, the corresponding single-stranded oligonucleotides are not aligned, with their persistence length being short in comparison to the lamellar interstitium thickness. We propose this as a model system for studying interactions of DNA-ligand complexes near a lipid bilayer membrane which we demonstrate by using dye probes that are either covalently attached to one end of the oligonucleotide or reversibly bound by intercalation between the base pairs. Three cationic dyes, all strongly bound by intercalation to DNA when free in solution, are found to not bind to DNA but to prefer the membrane surface. The covalently attached Cy5 also binds to the bilayer while Cy3 tends to end-stack to the oligonucleotide duplex. The orientation of Cy5 parallel to the membrane indicates that electrostatic surface binding predominates over insertion into the hydrophobic interior of the membrane. Anionic and zwitterionic dyes (FAM and ROX) are found to remain randomly oriented in the water between the lipid bilayer surfaces. © The Royal Society of Chemistry.

Functional BaTiO{sub 3} nanostructures immobilized onto si-based substrates using sol–gel and reverse micelle techniques

Energy Technology Data Exchange (ETDEWEB)

Mamana, Nadia, E-mail: nadia@fceia.unr.edu.ar; Pellegri, Nora [CONICET, FCEIyA, UNR, Laboratorio de Materiales Cerámicos IFIR (Argentina)

2015-03-15

The current tendency toward miniaturization of electronic devices has driven the interest in developing ferroelectric materials in low dimensions. In this work, for the preparation of lead-free BaTiO{sub 3} nanoparticles, we used a combination of the sol–gel method with the reverse micelles techniques. Moreover, previously to the thermal treatment, it was necessary to remove the surfactant. For this stage, oleic acid was used to stabilize the nanoparticles in the solution. Then, nanometer-sized particles were deposited on different substrates (Si, Pt/TiO{sub 2}/SiO{sub 2}/Si). The influence of different modes of deposition on particle size, degree of agglomeration, was analyzed. The mean particle size was 10 nm. Finally, the deposition of BaTiO{sub 3} particles on a conductive substrate such as the wafer of platinum (Pt/TiO{sub 2}/SiO{sub 2}/Si) was confirmed by several AFM techniques.

Fusion-activated Ca(2+ entry: an "active zone" of elevated Ca(2+ during the postfusion stage of lamellar body exocytosis in rat type II pneumocytes.

Directory of Open Access Journals (Sweden)

Pika Miklavc

2010-06-01

Full Text Available Ca(2+ is essential for vesicle fusion with the plasma membrane in virtually all types of regulated exocytoses. However, in contrast to the well-known effects of a high cytoplasmic Ca(2+ concentration ([Ca(2+](c in the prefusion phase, the occurrence and significance of Ca(2+ signals in the postfusion phase have not been described before.We studied isolated rat alveolar type II cells using previously developed imaging techniques. These cells release pulmonary surfactant, a complex of lipids and proteins, from secretory vesicles (lamellar bodies in an exceptionally slow, Ca(2+- and actin-dependent process. Measurements of fusion pore formation by darkfield scattered light intensity decrease or FM 1-43 fluorescence intensity increase were combined with analysis of [Ca(2+](c by ratiometric Fura-2 or Fluo-4 fluorescence measurements. We found that the majority of single lamellar body fusion events were followed by a transient (t(1/2 of decay = 3.2 s rise of localized [Ca(2+](c originating at the site of lamellar body fusion. [Ca(2+](c increase followed with a delay of approximately 0.2-0.5 s (method-dependent and in the majority of cases this signal propagated throughout the cell (at approximately 10 microm/s. Removal of Ca(2+ from, or addition of Ni(2+ to the extracellular solution, strongly inhibited these [Ca(2+](c transients, whereas Ca(2+ store depletion with thapsigargin had no effect. Actin-GFP fluorescence around fused LBs increased several seconds after the rise of [Ca(2+](c. Both effects were reduced by the non-specific Ca(2+ channel blocker SKF96365.Fusion-activated Ca(2+entry (FACE is a new mechanism that leads to [Ca(2+](c transients at the site of vesicle fusion. Substantial evidence from this and previous studies indicates that fusion-activated Ca(2+ entry enhances localized surfactant release from type II cells, but it may also play a role for compensatory endocytosis and other cellular functions.

Nucleation of the lamellar decomposition in a Ti-44Al-4Nb-4Zr alloy

Energy Technology Data Exchange (ETDEWEB)

Zhang, L.C.; Cheng, T.T.; Aindow, M

2004-01-05

The onset of the lamellar decomposition ({alpha}{yields}{alpha}{sub 2}+{gamma}) in a titanium aluminide alloy containing Nb and Zr has been studied by transmission electron microscopy. Samples water-quenched from the solution-treatment temperature of 1350 deg. C show fault-like features resembling those reported previously as the precursors for the formation of the {gamma} lamellae. High-resolution lattice images obtained from such features have revealed that the 'faults' are actually embryonic {gamma} lamellae, just a few atomic layers in thickness, which clearly exhibit the ordered L1{sub 0} structure. This implies that the {gamma} phase is formed directly, rather than via some intermediate disordered face-centred-cubic phase as suggested previously. Moreover, the character and configuration of the interfacial defects is consistent with this occurring in a diffusive-displacive manner with short-range fluxes across the risers of mobile perfect interfacial disconnections.

Nucleation of the lamellar decomposition in a Ti-44Al-4Nb-4Zr alloy

International Nuclear Information System (INIS)

Zhang, L.C.; Cheng, T.T.; Aindow, M.

2004-01-01

The onset of the lamellar decomposition (α→α 2 +γ) in a titanium aluminide alloy containing Nb and Zr has been studied by transmission electron microscopy. Samples water-quenched from the solution-treatment temperature of 1350 deg. C show fault-like features resembling those reported previously as the precursors for the formation of the γ lamellae. High-resolution lattice images obtained from such features have revealed that the 'faults' are actually embryonic γ lamellae, just a few atomic layers in thickness, which clearly exhibit the ordered L1 0 structure. This implies that the γ phase is formed directly, rather than via some intermediate disordered face-centred-cubic phase as suggested previously. Moreover, the character and configuration of the interfacial defects is consistent with this occurring in a diffusive-displacive manner with short-range fluxes across the risers of mobile perfect interfacial disconnections

Blueshift of the surface plasmon resonance in silver nanoparticles: substrate effects

DEFF Research Database (Denmark)

Raza, Søren; Yan, Wei; Stenger, Nicolas

2013-01-01

We study the blueshift of the surface plasmon (SP) resonance energy of isolated Ag nanoparticles with decreasing particle diameter, which we recently measured using electron energy loss spectroscopy (EELS) [1]. As the particle diameter decreases from 26 down to 3.5 nm, a large blueshift of 0.5 e......V of the SP resonance energy is observed. In this paper, we base our theoretical interpretation of our experimental findings on the nonlocal hydrodynamic model, and compare the effect of the substrate on the SP resonance energy to the approach of an effective homogeneous background permittivity. We derive...

Power electronics substrate for direct substrate cooling

Science.gov (United States)

Le, Khiet [Mission Viejo, CA; Ward, Terence G [Redondo Beach, CA; Mann, Brooks S [Redondo Beach, CA; Yankoski, Edward P [Corona, CA; Smith, Gregory S [Woodland Hills, CA

2012-05-01

Systems and apparatus are provided for power electronics substrates adapted for direct substrate cooling. A power electronics substrate comprises a first surface configured to have electrical circuitry disposed thereon, a second surface, and a plurality of physical features on the second surface. The physical features are configured to promote a turbulent boundary layer in a coolant impinged upon the second surface.

Gold Wire-networks: Particle Array Guided Evaporation Lithograpy

KAUST Repository

Lone, Saifullah; Zhang, Jiaming; Vakarelski, Ivan Uriev; Thoroddsen, Sigurdur T

2015-01-01

relies upon the defect free dry deposition of 2D monolayer of latex particles [2] on patterned silicon template and flat PDMS-substrate to create square centered and honey-comb wire networks respectively. The process is followed by lift-up transfer of 2D

Deposition of functionalized gold nanoparticles onto modified silicon substrates

Energy Technology Data Exchange (ETDEWEB)

Riskin, A.; Dobbelaere, C. de; Elen, K.; Rul, H. van den; Mullens, J.; Hardy, A. [Inorganic and Physical Chemistry, Institute for Materials Research, Hasselt University, Diepenbeek (Belgium); D' Haen, J. [Imecvzw Division IMOMEC, Diepenbeek (Belgium); Electrical and Physical Characterization, Institute for Materials Research, Hasselt University, Diepenbeek (Belgium); Bael, M.K. van [Inorganic and Physical Chemistry, Institute for Materials Research, Hasselt University, Diepenbeek (Belgium); Imecvzw Division IMOMEC, Diepenbeek (Belgium)

2010-04-15

In this report, an existing phase transfer method for the synthesis of alkylamine- or alkanethiol-functionalized gold nanoparticles (NPs) is investigated. A parameter study shows that the concentration of the gold salt used is important for the stability of the resulting sol, but has little effect on the final average particle size or the size distribution. By adding dodecanethiol before the reduction, the formation of NPs was inhibited, providing evidence for the autocatalytic pathway for the formation of metallic NPs in wet chemical synthesis proposed in the literature. The resulting functionalized gold NPs are deposited onto Si-OH, octadecyltrichlorosilane (OTS) or 3-mercaptopropyltrimethoxysilane modified SiO{sub 2}/Si substrates. scanning electron microscope (SEM) is used to analyze the ordering behavior and surface coverage of the NPs and it is shown that the difference in affinity for the substrate has a profound effect on the deposition behavior. The functionalization of the substrates and of the NPs is confirmed by grazing angle attenuated total reflectance fourier transform infrared spectroscopy (GATR-FTIR). (Abstract Copyright [2010], Wiley Periodicals, Inc.)

Responses of low pressure Andersen sampler for collecting substrates

Energy Technology Data Exchange (ETDEWEB)

Yamasaki, K. [Research Reactor Institute, Kyoto University, Osaka (Japan); Yamada, Y.; Miyamoto, K.; Shimo, M. [Division of Radiotoxicology and Protection, National Institute of Radiological Sciences, Chiba (Japan)

2000-05-01

Some types of low pressure cascade impactors (Andersen, Berner, Davies, and MOUDI etc) have been used to measure the activity size distribution of radon progeny in the environment. In spite of their careful uses, their nonideal responses are not adequately known. Some important factors such as the wall loss, electrostatic attraction, and the surface nature of collecting substrates may affect the reliability of the impactor data. Size selective characteristics of a low pressure Andersen sampler for various collecting substrates were examined in a radon exposure chamber using several kinds of liquid (DOS) or solid (carnauba wax) carrier aerosols labelled with radon progeny. These carrier aerosols were produced by commercial condensation aerosol generator. Tested collecting substrates were, (1) uncoated clean stainless steel plate, (2) silicone oil or grease coated stainless steel plate, (3) polyethylene sheet covered stainless steel plate, (4) membrane filter, (5) glass fiber filter, and (6) quartz fiber filter. In the case of collecting liquid or sticky carrier aerosols, the effect of particle bounce was small and nearly any substrates might used on the impaction plate. On the other hand, in the case of solid carrier aerosols, an adhesive layer such as grease or oil might have to be applied to the substrate. It was concluded that a low pressure cascade impactor such as Andersen sampler might need an appropriate calibration procedure including the interstage characteristics for determining the accurate activity size distribution. (author)

Radiative decay of surface plasmons on nonspherical silver particles

International Nuclear Information System (INIS)

Little, J.W.; Ferrell, T.L.; Callcott, T.A.; Arakawa, E.T.

1982-01-01

We have studied the radiation emitted by electron-bombarded silver particles. Electron micrographs have shown that the particles, obtained by heating thin (5 nm) silver films, were oblate (flattened) with minor axes aligned along the substrate normal. The characteristic wavelength obtained by bombarding these particles with 15-keV electrons was found to vary with angle of photon emission. We have modeled this wavelength shift as a result of the mixture of radiation from dipole and quadrupole surface-plasmon oscillations on oblate spheroids. Experimental observations of the energy, polarization, and angular distribution of the emitted radiation are in good agreement with theoretical calculations

Superconducting lead particles produced by chemical techniques

Science.gov (United States)

Fariss, T. L.; Nixon, W. E.; Bucelot, T. J.; Deaver, B. S., Jr.; Mitchell, J. W.

1982-09-01

The superconductivity of extremely small lead particles has been studied as a function of size, surface condition, and connectivity using chemical techniques to produce particles of well-controlled size and shape suspended in insulating media. Approximately monodisperse suspensions of equiaxed, rod, and lath-shaped particles of lead halides and other lead compounds suspended in gelatin, polyacrylamide, polyvinylpyrrolidone, polyvinyl alcohol, methyl cellulose, and hydroxyethyl cellulose have been produced. These particles have been reduced to pseudomorphs of lead in the liquid phase or the suspensions have been coated on substrates and dried before reduction. Reducing solutions containing aminoiminomethanesulfinic acid are effective with particles of lead halides, lead phosphate, lead sulfate, and lead tartrate. Suspensions of smaller discrete lead particles have also been produced by direct reduction of solutions of soluble lead salts containing suitable polymers, chelating, and stabilizing agents. Dispersions with mean particle dimensions between 3 nm and 5 μm, and a narrow size-frequency distribution, have been produced. The superconductivity of the particles has been characterized by measurements of the magnetization as a function of temperature and magnetic field. The larger particles have a transition temperature of 7.2 K, the same as bulk lead; however, for particles of characteristic dimensions less than 20 nm, the transition temperature is lower by ˜0.1 K.

Superconducting lead particles produced by chemical techniques

International Nuclear Information System (INIS)

Fariss, T.L.; Nixon, W.E.; Bucelot, T.J.; Deaver, B.S. Jr.; Mitchell, J.W.

1982-01-01

The superconductivity of extremely small lead particles has been studied as a function of size, surface condition, and connectivity using chemical techniques to produce particles of well-controlled size and shape suspended in insulating media. Approximately monodisperse suspensions of equiaxed, rod, and lath-shaped particles of lead halides and other lead compounds suspended in gelatin, polyacrylamide, polyvinylpyrrolidone, polyvinyl alcohol, methyl cellulose, and hydroxyethyl cellulose have been produced. These particles have been reduced to pseudomorphs of lead in the liquid phase or the suspensions have been coated on substrates and dried before reduction. Reducing solutions containing aminoiminomethanesulfinic acid are effective with particles of lead halides, lead phosphate, lead sulfate, and lead tartrate. Suspensions of smaller discrete lead particles have also been produced by direct reduction of solutions of soluble lead salts containing suitable polymers, chelating, and stabilizing agents. Dispersions with mean particle dimensions between 3 nm and 5 μm, and a narrow size-frequency distribution, have been produced. The superconductivity of the particles has been characterized by measurements of the magnetization as a function of temperature and magnetic field. The larger particles have a transition temperature of 7.2 K, the same as bulk lead; however, for particles of characteristic dimensions less than 20 nm, the transition temperature is lower by approx.0.1 K

Parallel nanostructuring of GeSbTe film with particle mask

Energy Technology Data Exchange (ETDEWEB)

Wang, Z.B.; Hong, M.H.; Wang, Q.F.; Chong, T.C. [Data Storage Institute, DSI Building, 5 Engineering Drive 1, 117608, Singapore (Singapore); Department of Electrical and Computer Engineering, National University of Singapore, 119260, Singapore (Singapore); Luk' yanchuk, B.S.; Huang, S.M.; Shi, L.P. [Data Storage Institute, DSI Building, 5 Engineering Drive 1, 117608, Singapore (Singapore)

2004-09-01

Parallel nanostructuring of a GeSbTe film may significantly improve the recording performance in data storage. In this paper, a method that permits direct and massively parallel nanopatterning of the substrate surface by laser irradiation is investigated. Polystyrene spherical particles were deposited on the surface in a monolayer array by self-assembly. The array was then irradiated with a 248-nm KrF laser. A sub-micron nanodent array can be obtained after single-pulse irradiation. These nanodents change their shapes at different laser energies. The optical near-field distribution around the particles was calculated according to the exact solution of the light-scattering problem. The influence of the presence of the substrate on the optical near field was also studied. The mechanisms for the generation of the nanodent structures are discussed. (orig.)

Resolução lamelar num novo microscópio eletrônico de varredura Lamellar resolution in a new scanning electron microscope

Directory of Open Access Journals (Sweden)

Hans-Jürgen Kestenbach

1997-03-01

Full Text Available RESUMO: Trabalhando com elétrons de baixa energia (na faixa de 1keV, o novo microscópio eletrônico de varredura dispensa a etapa de metalização e permite a observação direta da estrutura lamelar de polímeros semicristalinos, sem a necessidade de preparação de amostras. São apresentados exemplos da morfologia lamelar do PVDF em função das condições de processamento e da temperatura de cristalização, em filmes contendo as fases a, b e g. Um outro exemplo revela o crescimento inicial da camada transcristalina que se formou ao longo de uma fibra de polietileno de ultra-alto peso molecular embutida em matriz de polietileno de alta densidade.ABSTRACT: Working with low energy electrons (in the range of 1keV, the new scanning electron microscope permits the lamellar (supermolecular structure of semicrystalline polymers to be observed directly without the need of specimen coating or of any other sample preparation technique. Microscope performance is demonstrated by several examples of high resolution micrographs which show spherulitic, lamellar and fibrilar morphologies developed by the a, b and g phases of PVDF as a function of processing conditions and crystallization temperature. Another example reveals the early stages of transcrystalline layer formation in HDPE reinforced by UHMWPE fibers.

Structural characterization and gas reactions of small metal particles by high resolution in-situ TEM (Transmission Electron Microscopy) and TED (Transmission Electron Diffraction)

Science.gov (United States)

Heinemann, K.

1987-01-01

The detection and size analysis of small metal particles supported on amorphous substrates becomes increasingly difficult when the particle size approaches that of the phase contrast background structures of the support. An approach of digital image analysis, involving Fourier transformation of the original image, filtering, and image reconstruction was studied with respect to the likelihood of unambiguously detecting particles of less than 1 nm diameter on amorphous substrates from a single electron micrograph.

How does substrate roughness affect the service life of a superhydrophobic coating?

Science.gov (United States)

Zhang, Xin; Mo, Jiliang; Si, Yifan; Guo, Zhiguang

2018-05-01

Although the development of superhydrophobic coatings is rapidly maturing, issues related to their low mechanical durability persist. In this context, the effect of substrate roughness on the service life of superhydrophobic coatings was studied. In this study, superhydrophobic coatings were fabricated on sandpapers of different roughness and reciprocating wear tests were conducted. The wear-resistance number of the superhydrophobic coating, defined as the maximum number of friction cycles after which the superhydrophobic surface started to lose its superhydrophobicity, increased from 50 to 24,000 with an increase in the substrate roughness from 2000 CW to 240 CW (CW is defined as the number of particles arranged in an inch), while it decreased from 24,000 to 17,000 with a further increase in the substrate roughness from 240 CW to 60 CW. Observations of the surface structure and wear analyses indicated that the superhydrophobic material infiltrated the spaces between the sand grains, and the rough peaks could consequently protect the superhydrophobic material during the wear tests. However, this protection weakens when the substrate roughness increases or decreases beyond certain values. Furthermore, these phenomena and results were also verified by applying the superhydrophobic coatings to different types of common substrates.

Sintering of Fine Particles in Suspension Plasma Sprayed Coatings

Directory of Open Access Journals (Sweden)

Leszek Latka

2010-07-01

Full Text Available Suspension plasma spraying is a process that enables the production of finely grained nanometric or submicrometric coatings. The suspensions are formulated with the use of fine powder particles in water or alcohol with some additives. Subsequently, the suspension is injected into plasma jet and the liquid additives evaporate. The remaining fine solids are molten and subsequently agglomerate or remain solid, depending on their trajectory in the plasma jet. The coating’s microstructure results from these two groups of particles arriving on a substrate or previously deposited coating. Previous experimental studies carried out for plasma sprayed titanium oxide and hydroxyapatite coatings enabled us to observe either a finely grained microstructure or, when a different suspension injection mode was used, to distinguish two zones in the microstructure. These two zones correspond to the dense zone formed from well molten particles, and the agglomerated zone formed from fine solid particles that arrive on the substrate in a solid state. The present paper focuses on the experimental and theoretical analysis of the formation process of the agglomerated zone. The experimental section establishes the heat flux supplied to the coating during deposition. In order to achieve this, calorimetric measurements were made by applying experimental conditions simulating the real coatings’ growth. The heat flux was measured to be in the range from 0.08 to 0.5 MW/m2,depending on the experimental conditions. The theoretical section analyzes the sintering during the coating’s growth, which concerns the fine particles arriving on the substrate in the solid state. The models of volume, grain boundary and surface diffusion were analyzed and adapted to the size and chemistry of the grains, temperature and time scales corresponding to the suspension plasma spraying conditions. The model of surface diffusion was found to best describe the sintering during suspension

Fluorescence of molecules placed near a spherical particle: Rabi splitting

Directory of Open Access Journals (Sweden)

M.M. Dvoynenko

2017-12-01

Full Text Available Theoretical study of spontaneously emitted spectra of point-like source placed near spherical Ag particle was performed. It was shown that near-field electromagnetic interaction between a point-like emitter and spherical Ag particle leads to strong coupling between them at very small emitter-metal surface distances. It was shown that values of Rabi splitting are quantitatively close to that of emitter-flat substrate interaction.

Dissolution of aerosol particles collected from nuclear facility plutonium production process

International Nuclear Information System (INIS)

Ning Xu; Martinez, Alex; Schappert, Michael; Montoya, D.P.; Martinez, Patrick; Tandon, Lav

2016-01-01

A simple, robust analytical chemistry method has been developed to dissolve plutonium containing particles in a complex matrix. The aerosol particles collected on Marple cascade impactor substrates were shown to be dissolved completely with an acid mixture of 12 M HNO 3 and 0.1 M HF. A pressurized closed vessel acid digestion technique was utilized to heat the samples at 130 deg C for 16 h to facilitate the digestion. The dissolution efficiency for plutonium particles was 99 %. The resulting particle digestate solution was suitable for trace elemental analysis and isotope composition determination, as well as radiochemistry measurements. (author)

Single-particle Analyses of Compositions, Morphology, and Viscosity of Aerosol Particles Collected During GoAmazon2014

Science.gov (United States)

Adachi, K.; Gong, Z.; Bateman, A. P.; Martin, S. T.; Cirino, G. G.; Artaxo, P.; Sedlacek, A. J., III; Buseck, P. R.

2014-12-01

Single-particle analysis using transmission electron microscopy (TEM) shows composition and morphology of individual aerosol particles collected during the GoAmazon2014 campaign. These TEM results indicate aerosol types and mixing states, both of which are important for evaluating particle optical properties and cloud condensation nuclei activity. The samples were collected at the T3 site, which is located in the Amazon forest with influences from the urban pollution plume from Manaus. Samples were also collected from the T0 site, which is in the middle of the jungle with minimal to no influences of anthropogenic sources. The aerosol particles mainly originated from 1) anthropogenic pollution (e.g., nanosphere soot, sulfate), 2) biogenic emissions (e.g., primary biogenic particles, organic aerosols), and 3) long-range transport (e.g., sea salts). We found that the biogenic organic aerosol particles contain homogeneously distributed potassium. Particle viscosity is important for evaluating gas-particle interactions and atmospheric chemistry for the particles. Viscosity can be estimated from the rebounding behavior at controlled relative humidities, i.e., highly viscous particles display less rebound on a plate than low-viscosity particles. We collected 1) aerosol particles from a plate (non-rebounded), 2) those that had rebounded from the plate and were then captured onto an adjacent sampling plate, and 3) particles from ambient air using a separate impactor sampler. Preliminary results show that more than 90% of non-rebounded particles consisted of nanosphere soot with or without coatings. The coatings mostly consisted of organic matter. Although rebounded particles also contain nanosphere soot (number fraction 64-69%), they were mostly internally mixed with sulfate, organic matter, or their mixtures. TEM tilted images suggested that the rebounded particles were less deformed on the substrate, whereas the non-rebounded particles were more deformed, which could

Particle detector spatial resolution

International Nuclear Information System (INIS)

Perez-Mendez, V.

1992-01-01

Method and apparatus for producing separated columns of scintillation layer material, for use in detection of X-rays and high energy charged particles with improved spatial resolution is disclosed. A pattern of ridges or projections is formed on one surface of a substrate layer or in a thin polyimide layer, and the scintillation layer is grown at controlled temperature and growth rate on the ridge-containing material. The scintillation material preferentially forms cylinders or columns, separated by gaps conforming to the pattern of ridges, and these columns direct most of the light produced in the scintillation layer along individual columns for subsequent detection in a photodiode layer. The gaps may be filled with a light-absorbing material to further enhance the spatial resolution of the particle detector. 12 figs

Non-equilibrium work distribution for interacting colloidal particles under friction

International Nuclear Information System (INIS)

Gomez-Solano, Juan Ruben; July, Christoph; Mehl, Jakob; Bechinger, Clemens

2015-01-01

We experimentally investigate the non-equilibrium steady-state distribution of the work done by an external force on a mesoscopic system with many coupled degrees of freedom: a colloidal crystal mechanically driven across a commensurate periodic light field. Since this system mimics the spatiotemporal dynamics of a crystalline surface moving on a corrugated substrate, our results show general properties of the work distribution for atomically flat surfaces undergoing friction. We address the role of several parameters which can influence the shape of the work distribution, e.g. the number of particles used to locally probe the properties of the system and the time interval to measure the work. We find that, when tuning the control parameters to induce particle depinning from the substrate, there is an abrupt change of the shape of the work distribution. While in the completely static and sliding friction regimes the work distribution is Gaussian, non-Gaussian tails show up due to the spatiotemporal heterogeneity of the particle dynamics during the transition between these two regimes. (paper)

PREFACE: Cell-substrate interactions Cell-substrate interactions

Science.gov (United States)

Gardel, Margaret; Schwarz, Ulrich

2010-05-01

Discher D E 2010 How deeply cells feel: methods for thin gels J. Phys.: Condens. Matter 22 194116 [21] Jannat R A, Robbins G P, Ricart B G, Dembo M and Hammer D A 2010 Neutrophil adhesion and chemotaxis depend on substrate mechanics J. Phys.: Condens. Matter 22 194117 [22] Mogilner A and Rubinstein B 2010 Actin disassembly 'clock' and membrane tension determine cell shape and turning: a mathematical method J. Phys.: Condens. Matter 22 194118 [23] Saez A, Anon E, Ghibaudo M, du Roure O, Di Meglio J-M, Hersen P, Silberzan P, Buguin A, Ladoux B 2010 Traction forces exerted by epithelial cell sheets J. Phys.: Condens. Matter 22 194119 [24] Levental I, Levental K R, Klein E A, Assoian R, Miller R T, Wells R G and Janmey P A 2010 A simple indentation device for measuring micrometer-scale tissue stiffness J. Phys.: Condens. Matter 22 194120 [25] Kotlarchyk M A, Botvinick E L and Putnam A J 2010 Characterization of hydrogel microstructure using laser tweezers particle tracking and confocal reflection imaging J. Phys.: Condens. Matter 22 194121 [26] Narayanan H, Verner S N, Mills K L, Kemkemer R and Garikipati K 2010 In silico estimates of the free energy rates in growing tumor spheroids J. Phys.: Condens. Matter 22 194122

Effects of sintering temperature on the microstructural evolution and wear behavior of WCp reinforced Ni-based coatings

Science.gov (United States)

Chen, Chuan-hui; Bai, Yang; Ye, Xu-chu

2014-12-01

This article focuses on the microstructural evolution and wear behavior of 50wt%WC reinforced Ni-based composites prepared onto 304 stainless steel substrates by vacuum sintering at different sintering temperatures. The microstructure and chemical composition of the coatings were investigated by X-ray diffraction (XRD), differential thermal analysis (DTA), scanning and transmission electron microscopy (SEM and TEM) equipped with energy-dispersive X-ray spectroscopy (EDS). The wear resistance of the coatings was tested by thrust washer testing. The mechanisms of the decomposition, dissolution, and precipitation of primary carbides, and their influences on the wear resistance have been discussed. The results indicate that the coating sintered at 1175°C is composed of fine WC particles, coarse M6C (M=Ni, Fe, Co, etc.) carbides, and discrete borides dispersed in solid solution. Upon increasing the sintering temperature to 1225°C, the microstructure reveals few incompletely dissolved WC particles trapped in larger M6C, Cr-rich lamellar M23C6, and M3C2 in the austenite matrix. M23C6 and M3C2 precipitates are formed in both the γ/M6C grain boundary and the matrix. These large-sized and lamellar brittle phases tend to weaken the wear resistance of the composite coatings. The wear behavior is controlled simultaneously by both abrasive wear and adhesive wear. Among them, abrasive wear plays a major role in the wear process of the coating sintered at 1175°C, while the effect of adhesive wear is predominant in the coating sintered at 1225°C.

Rheophysics of Lamellar Phases Rhéophysiques de phases lamellaires

Directory of Open Access Journals (Sweden)

Roux D.

2006-12-01

Full Text Available We have developed several techniques to study the effect of shear on complex fluids. These techniques are based on shear cells specially adapted to scattering techniques or transport properties. A brief description of the cells will be given together with the results that can be obtained using these techniques. Exemples on lyotropic systems will be detailed. The effect of shear on lyotropic lamellar phases is studied by light scattering, neutron scattering and microscopic observations. We found three different states of orientation separated with out-of-equilibrium transitions. In the state at very low shear rate, the lamellar phase is, in average, oriented with the layers in the shear plane and a few dislocations remains in the direction of the flow. In the intermediate state, the layers organize themselves into monodisperse multilayer vesicles (MLV whose size is controlled by the shear rate. The last state corresponds to the same orientation than the first one but with no dislocations in the flow direction. The second state of orientation : leading to the MLV structure, is more precisely studied. It is shown that the size of the MLV is fixed by a balance between the viscous and elastic stresses and varies as the inverse square root of the shear rate. A possible mechanism for the formation of this structure is proposed. We show that this structure can be swollen in a solvent leading to a monodisperse emulsion of a lamellar structure in an isotropic liquid. Linear and nonlinear rheological properties are measured and discussed. It is shown that the viscosity is sensitive to the structure and varies of several order of magnitude depending in which phase of orientation the system is. Both shear thickening and shear thinning are described and explanations in terms or orientation transitions are given. The discovery of the oriented to MLV instability is the basis a very efficient process leading to well controlled microcapsules made of surfactant

Investigation on the Effect of Sulfur and Titanium on the Microstructure of Lamellar Graphite Iron

DEFF Research Database (Denmark)

Moumeni, Elham; Stefanescu, Doru Michael; Tiedje, Niels Skat

2013-01-01

The goal of this work was to identify the inclusions in lamellar graphite cast iron in an effort to explain the nucleation of the phases of interest. Four samples of approximately the same carbon equivalent but different levels of sulfur and titanium were studied. The Ti/S ratios were from 0...... of complex Al, Ca, Mg oxide. An increased titanium level of 0.35 pct produced superfine interdendritic graphite (~10 μm) at low (0.012 wt pct) as well as at high-S contents. Ti also caused increased segregation in the microstructure of the analyzed irons and larger eutectic grains (cells). TiC did not appear...... to be a nucleation site for the primary austenite as it was found mostly at the periphery of the secondary arms of the austenite, in the last region to solidify. The effect of titanium in refining the graphite and increasing the austenite fraction can be explained through the widening of the liquidus...

CuInS[sub 2] with lamellar morphology; 1: Efficient photoanodes in acidic polyiodide medium

Energy Technology Data Exchange (ETDEWEB)

Cattarin, S. (Inst. di Polarografia ed Elettrochimica Preparativa del C.N.R., Padova (Italy)); Dietz, N.; Lewerenz, H.J. (Hahn-Meitner-Inst., Berlin (Germany))

1994-05-01

CuInS[sub 2] grown in a steep temperature gradient acquires a peculiar lamellar morphology, similar to that of layered compound semiconductors. Thin electrodes (of thickness down to 30 to 40 [mu]m) can be prepared by cleavage, reducing series resistance in the bulk of the semiconductor. The liquid junction of n-CuInS[sub 2] with acidic polyiodide medium 2M HI, 2.5 M CaI[sub 2], 40 mM I[sub 2] was investigated. The best photoanodes attained quantum yields of monochromatic light of about 0.7 and conversion efficiencies above 7% under simulated AM1 sunlight. Their performance does not decrease substantially under moderately concentrated sunlight (300 to 400 mW cm[sup [minus]2]), due to small ohmic losses. Cell output appears quite stable during the first week of operation, but irregular electrode corrosion is observed, which may be detrimental to long term operation.

Dynamical phases of attractive particles sliding on a structured surface

International Nuclear Information System (INIS)

Hasnain, J; Jungblut, S; Dellago, C

2015-01-01

Inspired by experiments on quartz crystal microbalance setups, we study the mobility of a monolayer of Lennard-Jones particles driven over a hexagonal external potential. We pay special attention to the changes in the dynamical phases that arise when the lattice constant of the external substrate potential and the Lennard-Jones interaction are mismatched. We find that if the average particle separation is such that the particles repel each other, or interact harmonically, the qualitative behavior of the system is akin to that of a monolayer of purely repulsive Yukawa particles. On the other hand, if the particles typically attract each other, the ensuing dynamical states are determined entirely by the relative strength of the Lennard-Jones interaction with respect to that of the external potential. (paper)

Gold nanoparticle growth control - Implementing novel wet chemistry method on silicon substrate

KAUST Repository

Al-Ameer, Ammar

2013-04-01

Controlling particle size, shape, nucleation, and self-assembly on surfaces are some of the main challenges facing electronic device fabrication. In this work, growth of gold nanoparticles over a wide range of sizes was investigated by using a novel wet chemical method, where potassium iodide is used as the reducing solution and gold chloride as the metal precursor, on silicon substrates. Four parameters were studied: soaking time, solution temperature, concentration of the solution of gold chloride, and surface pre-treatment of the substrate. Synthesized nanoparticles were then characterized using scanning electron microscopy (SEM). The precise control of the location and order of the grown gold overlayer was achieved by using focused ion beam (FIB) patterning of a silicon surface, pre-treated with potassium iodide. By varying the soaking time and temperature, different particle sizes and shapes were obtained. Flat geometrical shapes and spherical shapes were observed. We believe, that the method described in this work is potentially a straightforward and efficient way to fabricate gold contacts for microelectronics. © 2013 IEEE.

Structure, apatite inducing ability, and corrosion behavior of chitosan/halloysite nanotube coatings prepared by electrophoretic deposition on titanium substrate.

Science.gov (United States)

Molaei, A; Amadeh, A; Yari, M; Reza Afshar, M

2016-02-01

In this study chitosan/halloysite nanotube composite (CS/HNT) coatings were deposited by electrophoretic deposition (EPD) on titanium substrate. Using HNT particles were investigated as new substituents for carbon nanotubes (CNTs) in chitosan matrix coatings. The ability of chitosan as a stabilizing, charging, and blending agent for HNT particles was exploited. Furthermore, the effects of pH, electrophoretic bath, and sonicating duration were studied on the deposition of suspensions containing HNT particles. Microstructure properties of coatings showed uniform distribution of HNT particles in chitosan matrix to form smooth nanocomposite coatings. The zeta potential results revealed that at pH around 3 there is an isoelectric point for HNT and it would have cathodic and anionic states at pH values less and more than 3, respectively. Therefore, CS/HNT composite deposits were produced in the pH range of 2.5 to 3. The apatite inducing ability of chitosan-HNT composite coating assigned that HNT particles were biocompatible because they formed carbonated hydroxyapatite particles on CS/HNT coating in corrected simulated body fluid (C-SBF). Finally, electrochemical corrosion characterizations determined that corrosion resistance in CS/HNT coating has been improved compared to bare titanium substrate. Copyright © 2015 Elsevier B.V. All rights reserved.

Acanthamoeba polyphaga mimivirus stability in environmental and clinical substrates: implications for virus detection and isolation.

Directory of Open Access Journals (Sweden)

Fábio P Dornas

Full Text Available Viruses are extremely diverse and abundant and are present in countless environments. Giant viruses of the Megavirales order have emerged as a fascinating research topic for virologists around the world. As evidence of their ubiquity and ecological impact, mimiviruses have been found in multiple environmental samples. However, isolation of these viruses from environmental samples is inefficient, mainly due to methodological limitations and lack of information regarding the interactions between viruses and substrates. In this work, we demonstrate the long-lasting stability of mimivirus in environmental (freshwater and saline water and hospital (ventilator plastic device tube substrates, showing the detection of infectious particles after more than 9 months. In addition, an enrichment protocol was implemented that remarkably increased mimivirus detection from all tested substrates, including field tests. Moreover, biological, morphological and genetic tests revealed that the enrichment protocol maintained mimivirus particle integrity. In conclusion, our work demonstrated the stability of APMV in samples of environmental and health interest and proposed a reliable and easy protocol to improve giant virus isolation. The data presented here can guide future giant virus detection and isolation studies.

Inner Stucture of Thin Films of Lamellar Poly(styrene-em>b>-butadiene) Diblock Copolymers as revealed by Grazing-Incidence Small-Angle Scattering

DEFF Research Database (Denmark)

Busch, Peter; Posselt, Dorthe; Smilgies, Detlef-Matthias

2007-01-01

The lamellar orientation in supported, thin films of poly(styrene-b-butadiene) (P(S-b-B)) depends on block copolymer molar mass. We have studied films from nine block copolymer samples with molar masses between 13.9 and 183 kg/mol using grazing-incidence small-angle X-ray scattering (GISAXS) and ...... quantitatively in the framework of our recently developed distorted-wave Born approximation model (Busch, P.; et al. J. Appl. Crystallogr. 2006, 39, 433). The results cannot be explained from enthalpic considerations alone but point to the importance of entropic factors....

Effects of alpha particles on zebrafish embryos

International Nuclear Information System (INIS)

Yum, E.H.W.; Choi, V.W.Y.; Yu, K.N.; Li, V.W.T.; Cheng, S.H.

2008-01-01

Full text: Ionizing radiation such as X-ray and alpha particles can damage cellular macromolecules, which can lead to DNA single- and double-strand breaks. In the present work, we studied the effects of alpha particles on dechorionated zebrafish embryos. Thin polyallyldiglycol carbonate (PADC) films with a thickness of 16 μm were prepared from commercially available PADC films (with thickness of 100 μm) by chemical etching and used as support substrates for holding zebrafish embryos for alpha-particle irradiation. These films recorded alpha-particle hit positions, quantified the number and energy of alpha particles actually incident on the embryo cells, and thus enabled the calculation of the dose absorbed by the embryo cells. Irradiation was made at 1.25 hours post fertilization (hpf) with various absorbed dose. TdT-mediated dUTP Nick-End Labeling (TUNEL) assay was performed on the embryos at different time stages after irradiation. Marked apoptosis was detected only in embryos at earlier time stages. The results showed that DNA double-strand break during zebrafish embryogenesis can be induced by alpha-particle irradiation, which suggests that zebrafish is a potential model for assessing the effects of alpha-particle radiation

Bidisperse silica nanoparticles close-packed monolayer on silicon substrate by three step spin method

Science.gov (United States)

Khanna, Sakshum; Marathey, Priyanka; Utsav, Chaliawala, Harsh; Mukhopadhyay, Indrajit

2018-05-01

We present the studies on the structural properties of monolayer Bidisperse silica (SiO2) nanoparticles (BDS) on Silicon (Si-100) substrate using spin coating technique. The Bidisperse silica nanoparticle was synthesised by the modified sol-gel process. Nanoparticles on the substrate are generally assembled in non-close/close-packed monolayer (CPM) form. The CPM form is obtained by depositing the colloidal suspension onto the silicon substrate using complex techniques. Here we report an effective method for forming a monolayer of bidisperse silica nanoparticle by three step spin coating technique. The samples were prepared by mixing the monodisperse solutions of different particles size 40 and 100 nm diameters. The bidisperse silica nanoparticles were self-assembled on the silicon substrate forming a close-packed monolayer film. The scanning electron microscope images of bidisperse films provided in-depth film structure of the film. The maximum surface coverage obtained was around 70-80%.

Effect of substrate temperature and post annealing temperature on ZnO:Zn PLD thin film properties

Science.gov (United States)

Hasabeldaim, E.; Ntwaeaborwa, O. M.; Kroon, R. E.; Coetsee, E.; Swart, H. C.

2017-12-01

The pulsed laser deposition (PLD) substrate temperature and post-annealing temperature are effective methods to control the film optical and structural properties. The structure, morphology and optical properties of the deposited and post-annealed PLD ZnO:Zn films were studied. The films were deposited at different substrate temperatures of 50 °C, 200 °C and 400 °C. The films deposited at the substrate temperature of 50 °C and 200 °C were post-annealed in air at 400 °C and 600 °C for two hours. The films all had a highly preferential orientation with the hexagonal c-axis perpendicular to the substrate surface. The stress was found to be compressive stress with values -3.289 GPa, -4.864 GPa and -4.425 GPa for the film deposited at 50 °C, 200 °C and 400 °C, respectively. After post-annealing treatments, the stress of the films was almost completely released and stress-free films were obtained. The crystallite sizes were 19 nm, 25 nm and 39 nm, while the average particles sizes were 95 nm, 85 nm and 129 nm for the film deposited at 50 °C, 200 °C and 400 °C respectively. The crystallite sizes and particles sizes seemed to increase with the increase in the substrate temperature. Contrary to this, the change in crystallite sizes were inversely proportional to the particles size when increasing the post-annealing temperatures. Deconvoluted X-ray photoelectron spectroscopy peaks of the O1s binding energy region revealed that the films deposited at different substrate temperatures contained oxygen-related defects. Photoluminescence studies revealed that the films all emitted ultra-violet emission around 379 nm. The film deposited at 50 °C emitted a broad green emission centered at ∼524 nm. By increasing the substrate temperature up to 200 °C and 400 °C a new orange emission around 621 nm and 634 nm as well as a weak emission around 416 nm and 500 nm were observed, respectively. After post-annealing treatments, new bands over the visible region (blue, green

Ratchet Effects, Negative Mobility, and Phase Locking for Skyrmions on Periodic Substrates

Science.gov (United States)

Reichhardt, Charles; Ray, Dipanjan; Olson Reichhardt, Cynthia

We examine the dynamics of skyrmions interacting with 1D and 2D periodic substrates in the presence of dc and ac drives. We find that the Magnus term strongly affects the skyrmion dynamics and that new kinds of phenomena can occur which are absent for overdamped ac and dc driven particles interacting with similar substrates. We show that it is possible to realize a Magnus induced ratchet for skyrmions interacting with an asymmetric potential, where the application of an ac drive can produce quantized dc motion of the skyrmions even when the ac force is perpendicular to the substrate asymmetry direction. For symmetric substrates it is also possible to achieve a negative mobility effect where the net skyrmion motion runs counter to an applied dc drive. Here, as a function of increasing dc drive, the velocity-force curves show a series of locking phases that have different features from the classic Shapiro steps found in overdamped systems. In the phase locking and ratcheting states, the skyrmions undergo intricate 2D orbits induced by the Magnus term.

Influence of electropulsing globularization on the microstructure and mechanical properties of Ti–6Al–4V alloy strip with lamellar microstructure

Energy Technology Data Exchange (ETDEWEB)

Ye, Xiaoxin, E-mail: xiaoxinye905@gmail.com [Advanced Materials Institute, Graduate School at Shenzhen, Tsinghua University, Shenzhen 518055 (China); Key Laboratory for Advanced Materials of Ministry of Education, Department of Materials Science and Engineering, Tsinghua University, Beijing 100084 (China); Tse, Zion T.H. [College of Engineering, The University of Georgia, Athens, GA 30602 (United States); Tang, Guoyi, E-mail: tanggy@mails.tsinghua.edu.cn [Advanced Materials Institute, Graduate School at Shenzhen, Tsinghua University, Shenzhen 518055 (China); Key Laboratory for Advanced Materials of Ministry of Education, Department of Materials Science and Engineering, Tsinghua University, Beijing 100084 (China); Geng, Yubo [Advanced Materials Institute, Graduate School at Shenzhen, Tsinghua University, Shenzhen 518055 (China); Key Laboratory for Advanced Materials of Ministry of Education, Department of Materials Science and Engineering, Tsinghua University, Beijing 100084 (China); Song, Guolin [Advanced Materials Institute, Graduate School at Shenzhen, Tsinghua University, Shenzhen 518055 (China)

2015-01-12

The effect of high-energy electropulsing treatment (EPT) on the microstructure and mechanical properties of Ti–6Al–4V alloy strip with initial lamellar microstructure was investigated. The results indicated that EPT accelerated the phase change process tremendously inducing equiaxed microstructure in titanium alloy. The EPT-induced microstructural change resulted in remarkably increasing elongation-to-failure while the tensile strength remained unchanged. A mechanism for rapid phase change in low temperature during EPT was proposed based on the reduction of nucleation thermodynamic barrier and enhancement of atomic diffusion. A medium migration model was utilized for discussing the globularization process.

Influence of electropulsing globularization on the microstructure and mechanical properties of Ti–6Al–4V alloy strip with lamellar microstructure

International Nuclear Information System (INIS)

Ye, Xiaoxin; Tse, Zion T.H.; Tang, Guoyi; Geng, Yubo; Song, Guolin

2015-01-01

The effect of high-energy electropulsing treatment (EPT) on the microstructure and mechanical properties of Ti–6Al–4V alloy strip with initial lamellar microstructure was investigated. The results indicated that EPT accelerated the phase change process tremendously inducing equiaxed microstructure in titanium alloy. The EPT-induced microstructural change resulted in remarkably increasing elongation-to-failure while the tensile strength remained unchanged. A mechanism for rapid phase change in low temperature during EPT was proposed based on the reduction of nucleation thermodynamic barrier and enhancement of atomic diffusion. A medium migration model was utilized for discussing the globularization process

Boron Behavior Induced Lamellar Structure and Anisotropic Magnetic Properties of Nd{sub 2}Fe{sub 14}B during HDDR process

Energy Technology Data Exchange (ETDEWEB)

Choi, Moonhee; Song, Yeonghwan [Samsung Electro-Mechanics, Suwon (Korea, Republic of); Cho, Seungchan; Jo, Ilguk; Yu, Jihun [Korea Institute of Materials Science, Changwon (Korea, Republic of); Kim, Chiho; Kim, Yangdo [Pusan National University, Busan (Korea, Republic of)

2017-08-15

The anisotropy of the Nd{sub 2}Fe{sub 14}B powder is originated during the creation of a fine Fe2B lamellar structure in the disproportionation step. The aspect ratio (A/R) of Fe2B structure increased from 3.37 ± 1.5 to 6.69 ± 3.2 during phase decomposition for 0 ∼ 60 min at 820 ℃ (P{sub H2} = 10 kPa). The Fe{sub 2}B having high A/R ratio recombined Nd{sub 2}Fe{sub 14}B, which is close to the single domain, and the magnetic properties are also improved with increasing A/R ratio.

Thermal Stability of Silver Paste Sintering on Coated Copper and Aluminum Substrates

Science.gov (United States)

Pei, Chun; Chen, Chuantong; Suganuma, Katsuaki; Fu, Guicui

2018-01-01

The thermal stability of silver (Ag) paste sintering on coated copper (Cu) and aluminum (Al) substrates has been investigated. Instead of conventional zincating or nickel plating, magnetron sputtering was used to achieve coating with titanium (Ti) and Ag. Silicon (Si) chips were bonded to coated Cu and Al substrates using a mixture of submicron Ag flakes and particles under 250°C and 0.4 MPa for 30 min. The joints were then subject to aging testing at 250°C for duration of 200 h, 500 h, and 1000 h. Two types of joints exhibited satisfactory initial shear strength above 45 MPa. However, the shear strength of the joints on Al substrate decreased to 28 MPa after 1000 h of aging, while no shear strength decline was detected for the joints on Cu substrate. Fracture surface analysis revealed that the vulnerable points of the two types of joints were (1) the Ag layer and (2) the interface between the Ti layer and Cu substrate. Based on the results of scanning electron microscopy (SEM), energy-dispersive x-ray spectroscopy (EDS), and simulations, cracks in the Ag layer were identified as the cause of the shear strength degradation in the joints on Al substrate. The interface evolution of the joints on Cu substrate was ascribed to Cu migration and discontinuity points that initialized in the Ti layer. This study reveals that Al exhibited superior thermal stability with sintered Ag paste.

Structure evolution of the LiMnO{sub 2} lamellar oxide during electrochemical cycling; Evolution structurale de l`oxyde lamellaire LiMnO{sub 2} lors du cyclage electrochimique

Energy Technology Data Exchange (ETDEWEB)

Delmas, C. [Centre National de la Recherche Scientifique (CNRS), 33 - Pessac (France). Institut de Chimie de la Matiere Condensee de Bordeaux; Capitaine, F.; Majastre [Bollore Technologies, 29 - Quimper (France); Baudry, P. [Electricite de France, 77 - Moret sur Loing (France). Direction des Etudes et Recherches

1996-12-31

The LiMnO{sub 2} lamellar oxide, obtained by exchange reaction from its sodium homologue {alpha}-NaMnO{sub 2}, has been used as a positive electrode for lithium batteries. After the first electrochemical cycle, the shape of the potential-composition curve changes and indicates a change in the structure. This modification changes imperceptibly at each cycle and after about 40 cycles, a stationary state is reached. Powder spectra refinement using the Rietvelt method shows a migration of manganese ions from the thin sheets towards the inter-sheet space. After a single cycle, 8% of the manganese ions are already present in the lithium site and this rate reaches 13% after 3 cycles. During long cycling, a redistribution of ions and vacancies inside the cfc oxygenated pile leads to a structure very similar to the LiMn{sub 2}O{sub 4} spinel. This structure evolution is to be compared with the one obtained from the orthorhombic variety of LiMnO{sub 2} but the modification is more progressive with lamellar LiMnO{sub 2}. Abstract only. (J.S.)

Structure evolution of the LiMnO{sub 2} lamellar oxide during electrochemical cycling; Evolution structurale de l`oxyde lamellaire LiMnO{sub 2} lors du cyclage electrochimique

Energy Technology Data Exchange (ETDEWEB)

Delmas, C [Centre National de la Recherche Scientifique (CNRS), 33 - Pessac (France). Institut de Chimie de la Matiere Condensee de Bordeaux; Capitaine, F; Majastre, [Bollore Technologies, 29 - Quimper (France); Baudry, P [Electricite de France, 77 - Moret sur Loing (France). Direction des Etudes et Recherches

1997-12-31

The LiMnO{sub 2} lamellar oxide, obtained by exchange reaction from its sodium homologue {alpha}-NaMnO{sub 2}, has been used as a positive electrode for lithium batteries. After the first electrochemical cycle, the shape of the potential-composition curve changes and indicates a change in the structure. This modification changes imperceptibly at each cycle and after about 40 cycles, a stationary state is reached. Powder spectra refinement using the Rietvelt method shows a migration of manganese ions from the thin sheets towards the inter-sheet space. After a single cycle, 8% of the manganese ions are already present in the lithium site and this rate reaches 13% after 3 cycles. During long cycling, a redistribution of ions and vacancies inside the cfc oxygenated pile leads to a structure very similar to the LiMn{sub 2}O{sub 4} spinel. This structure evolution is to be compared with the one obtained from the orthorhombic variety of LiMnO{sub 2} but the modification is more progressive with lamellar LiMnO{sub 2}. Abstract only. (J.S.)

Characterization of active CMOS pixel sensors on high resistive substrate

Energy Technology Data Exchange (ETDEWEB)

Hirono, Toko; Hemperek, Tomasz; Huegging, Fabian; Krueger, Hans; Rymaszewski, Piotr; Wermes, Norbert [Physikalisches Institut, Universitaet Bonn, Bonn (Germany)

2016-07-01

Active CMOS pixel sensors are very attractive as radiation imaging pixel detector because they do not need cost-intensive fine pitch bump bonding. High radiation tolerance and time resolution are required to apply those sensors to upcoming particle physics experiments. To achieve these requirements, the active CMOS pixel sensors were developed on high resistive substrates. Signal charges are collected faster by drift in high resistive substrates than in standard low resistive substrates yielding also a higher radiation tolerance. A prototype of the active CMOS pixel sensor has been fabricated in the LFoundry 150 nm CMOS process on 2 kΩcm substrate. This prototype chip was thinned down to 300 μm and the backside has been processed and can contacted by an aluminum contact. The breakdown voltage is around -115 V, and the depletion width has been measured to be as large as 180 μm at a bias voltage of -110 V. Gain and noise of the readout circuitry agree with the designed values. Performance tests in the lab and test beam have been done before and after irradiation with X-rays and neutrons. In this presentation, the measurement results of the active CMOS prototype sensors are shown.

Controlling the optical properties of gold nanoparticles periodic arrays by changing their topologic shapes and substrate properties

International Nuclear Information System (INIS)

Li Ting; Yu Li; Lu Zhixin; Song Gang; Liu Bin

2011-01-01

We investigated the influence of extinction of gold nanoparticles periodic arrays by varying the substrate properties and the shapes of nanoparticles with the full vectorial three dimensional finite difference time domain method. Substrates of different thicknesses and dielectric constants and ten topologically different gold nanostructures including diamond, cycle ring, rectangle ring, pentagon ring, five-pointed star, flower shape, L, Y, T and X shapes are considered. The results show that substrate properties have a significant impact on the extinction spectrum due to coupling of the modes excited in substrates and the one excited by localized surface plasmon. The extinction spectra are changed with the different shapes of nanoparticles periodic array. However, with similar structure particles periodic arrays, the extinction spectra appear similar in the visible regime. Therefore we can find an eligible shape and substrate which can be used in integrated devises.

Effect of Nanosilica Filled Polyurethane Composite Coating on Polypropylene Substrate

Directory of Open Access Journals (Sweden)

Yern Chee Ching

2013-01-01

Full Text Available Acrylic based polyurethane (PU coatings with various amounts of nanosilica contents were prepared using solution casting method. The nanosilica (SiO2 particles used are around 16 nm in diameter. The friction and wear test was conducted using the reciprocating wear testing machine. The tests were performed at rotary speed of 100 rpm and 200 rpm with load of 0.1 kg to 0.4 kg under 1 N interval. The effect of the PU/nano-SiO2 composite coating on friction and wear behavior of polypropylene substrate was investigated and compared. The worn surface of coating film layer after testing was investigated by using an optical microscope. The introduction of PU/nanosilica composite coating containing 3 wt% of nano-SiO2 content gives the lowest friction coefficient and wear rate to PP substrate. Both the friction and wear rate of PP substrate coated with >3 wt% of nano-SiO2 filled PU coating would increase with the increasing of applied load and sliding time.

Comparative Study of Electroless Copper Film on Different Self-Assembled Monolayers Modified ABS Substrate

Directory of Open Access Journals (Sweden)

Jiushuai Xu

2014-04-01

Full Text Available Copper films were grown on (3-Mercaptopropyltrimethoxysilane (MPTMS, (3-Aminopropyltriethoxysilane (APTES and 6-(3-(triethoxysilylpropylamino-1,3,5- triazine-2,4-dithiol monosodium (TES self-assembled monolayers (SAMs modified acrylonitrile-butadiene-styrene (ABS substrate via electroless copper plating. The copper films were examined using scanning electron microscopy (SEM and X-ray diffraction (XRD. Their individual deposition rate and contact angle were also investigated to compare the properties of SAMs and electroless copper films. The results indicated that the formation of copper nuclei on the TES-SAMs modified ABS substrate was faster than those on the MPTMS-SAMs and APTES-SAMs modified ABS substrate. SEM images revealed that the copper film on TES-SAM modified ABS substrate was smooth and uniform, and the density of copper nuclei was much higher. Compared with that of TES-SAMs modified resin, the coverage of copper nuclei on MPTMS and APTES modified ABS substrate was very limited and the copper particle size was too big. The adhesion property test demonstrated that all the SAMs enhanced the interfacial interaction between copper plating and ABS substrate. XRD analysis showed that the copper film deposited on SAM-modified ABS substrate had a structure with Cu(111 preferred orientation, and the copper film deposited on TES-SAMs modified ABS substrate is better than that deposited on MPTMS-SAMs or APTES-SAMs modified ABS resins in electromigrtion resistance.

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

Science.gov (United States)

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

2018-04-01

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

Effects of Exposed Artificial Substrate on the Competition between Phytoplankton and Benthic Algae: Implications for Shallow Lake Restoration

OpenAIRE

Hu He; Xuguang Luo; Hui Jin; Jiao Gu; Erik Jeppesen; Zhengwen Liu; Kuanyi Li

2017-01-01

Phytoplankton and benthic algae coexist in shallow lakes and the outcome of the competition between these two photoautotrophs can markedly influence water clarity. It is well established that exposed artificial substrate in eutrophic waters can remove nutrients and fine particles from the water column via the attached periphyton canopy. However, the effects of the introduction of artificial substrate on the competition between planktonic and benthic primary producers remain to be elucidated. ...

Hydrophobic nanoparticles promote lamellar to inverted hexagonal transition in phospholipid mesophases.

Science.gov (United States)

Bulpett, Jennifer M; Snow, Tim; Quignon, Benoit; Beddoes, Charlotte M; Tang, T-Y D; Mann, Stephen; Shebanova, Olga; Pizzey, Claire L; Terrill, Nicholas J; Davis, Sean A; Briscoe, Wuge H

2015-12-07

This study focuses on how the mesophase transition behaviour of the phospholipid dioleoyl phosphatidylethanolamine (DOPE) is altered by the presence of 10 nm hydrophobic and 14 nm hydrophilic silica nanoparticles (NPs) at different concentrations. The lamellar to inverted hexagonal phase transition (Lα-HII) of phospholipids is energetically analogous to the membrane fusion process, therefore understanding the Lα-HII transition with nanoparticulate additives is relevant to how membrane fusion may be affected by these additives, in this case the silica NPs. The overriding observation is that the HII/Lα boundaries in the DOPE p-T phase diagram were shifted by the presence of NPs: the hydrophobic NPs enlarged the HII phase region and thus encouraged the inverted hexagonal (HII) phase to occur at lower temperatures, whilst hydrophilic NPs appeared to stabilise the Lα phase region. This effect was also NP-concentration dependent, with a more pronounced effect for higher concentration of the hydrophobic NPs, but the trend was less clear cut for the hydrophilic NPs. There was no evidence that the NPs were intercalated into the mesophases, and as such it was likely that they might have undergone microphase separation and resided at the mesophase domain boundaries. Whilst the loci and exact roles of the NPs invite further investigation, we tentatively discuss these results in terms of both the surface chemistry of the NPs and the effect of their curvature on the elastic bending energy considerations during the mesophase transition.

Considerations in the selection of model substrates for microbiological effects research

International Nuclear Information System (INIS)

Francis, A.J.; Rose, A.W.

1984-01-01

The physical and chemical characteristics of several energy residues have been briefly reviewed in order to select a model or representative substrate of basic research to determine the significance of anaerobic microbial dissolution and mobilization or immobilization of toxic trace elements under subsurface environmental conditions. The major factors which influence the dissolution and mobilization of trace metals have been critically examined, e.g., (i) effects on pH of leachates (pyrite oxidation), soluble acid, and basic compounds; (ii) effects on oxidation state of leachates (oxidation state of Fe, presence of organics); (iii) concentration of toxic inorganic species, and chemical form; (iv) surface area of waste particles; and (v) physical strength and particle size, with resulting effects on permeability of the substrate. Several major physical and chemical characteristics are common to energy-related residues yet each of these materials has a unique set of physical and chemical properties. The pros and cons of selecting a single model substrate for microbiological research were discussed at the Geochemical and Biochemical Working Group Meeting and use of the end-member concept was suggested. From the abundance, distribution, forms of trace metals present, and volume of these metal-containing residues disposed of in the subsurface environments, microbiological studies can be performed with coal beneficiation and coal gasification residues under a variety of subsurface environmental conditions, and results can be validated in the field. The basic scientific information obtained from this research can be applied to other materials of similar composition. 18 references, 3 figures, 7 tables

Some peculiarity of element analysis using charged particle beams

International Nuclear Information System (INIS)

Kobzev, A.P.; Abu-Alazm, S.M.; Helal, A.I.; Zahran, N.F.

2002-01-01

Multilayer structures, SiC -layers at Si substrate, have been analyzed by RBS, NR, ERD and PIXE methods using the charged particle beams from EG-5 Van de Graaff accelerator of JINR. The depth profiles of the based deposited layers were obtained for the multilayer structures

Nanoparticle manipulation in the near-substrate areas of low-temperature, high-density rf plasmas

International Nuclear Information System (INIS)

Rutkevych, P.P.; Ostrikov, K.; Xu, S.

2005-01-01

Manipulation of a single nanoparticle in the near-substrate areas of high-density plasmas of low-temperature glow discharges is studied. It is shown that the nanoparticles can be efficiently manipulated by the thermophoretic force controlled by external heating of the substrate stage. Particle deposition onto or repulsion from nanostructured carbon surfaces critically depends on the values of the neutral gas temperature gradient in the near-substrate areas, which is directly measured in situ in different heating regimes by originally developed temperature gradient probe. The measured values of the near-surface temperature gradient are used in the numerical model of nanoparticle dynamics in a variable-length presheath. Specific conditions enabling the nanoparticle to overcome the repulsive potential and deposit on the substrate during the discharge operation are investigated. The results are relevant to fabrication of various nanostructured films employing structural incorporation of the plasma-grown nanoparticles, in particular, to nanoparticle deposition in the plasma-enhanced chemical-vapor deposition of carbon nanostructures in hydrocarbon-based plasmas

Comparison of W–TiC composite coatings fabricated by atmospheric plasma spraying and supersonic atmospheric plasma spraying

International Nuclear Information System (INIS)

Hou, Qing Yu; Luo, Lai Ma; Huang, Zhen Yi; Wang, Ping; Ding, Ting Ting; Wu, Yu Cheng

2016-01-01

Highlights: • W–TiC composite coatings were fabricated by APS and SAPS technologies. • TiC had filling effect on pores and coating/fixing effect on un-melted particles. • Porosity and oxygen content in SAPS coating were lower than that in APS coating. • Thermal conductivity of SAPS coating was higher than that of APS coating. • SAPS coating has better ability to resist to elastic fracture than APS coating does. - Abstract: Tungsten coatings with 1.5 wt.% TiC (W/TiC) were fabricated by atmospheric plasma spraying (APS) and supersonic atmospheric plasma spraying (SAPS) techniques, respectively. The results showed that the typical lamellar structure of plasma spraying and columnar crystalline grains formed in the coatings. Pores located mainly at lamellar gaps in association with oxidation were also observed. TiC phase, distributed at lamellar gaps filled the gaps; and that distributed around un-melted tungsten particles and splashed debris coated the particles or debris that were linked with the TiC at lamellar gaps. The coating and linking of the retained TiC phase prevented the tungsten particles to come off from the coatings. The porosity and the oxygen content of the SAPS-W/TiC were lower than those of the APS-W/TiC coating. The mechanical response of the coatings was strongly dependent on the H/E* ratio (H and E* are the hardness and effective Young’s modulus, respectively). The SAPS-W/TiC coating with a higher H/E* ratio had a better ability to resist to elastic fracture and better fracture toughness as compared with the APS-W/TiC coating with a smaller H/E* ratio. The thermal conductivity of the SAPS-W/TiC coating was greater than that of the APS-W/TiC coating.

Surface Structures Formed by a Copper(II Complex of Alkyl-Derivatized Indigo

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Akinori Honda

2016-10-01

Full Text Available Assembled structures of dyes have great influence on their coloring function. For example, metal ions added in the dyeing process are known to prevent fading of color. Thus, we have investigated the influence of an addition of copper(II ion on the surface structure of alkyl-derivatized indigo. Scanning tunneling microscope (STM analysis revealed that the copper(II complexes of indigo formed orderly lamellar structures on a HOPG substrate. These lamellar structures of the complexes are found to be more stable than those of alkyl-derivatized indigos alone. Furthermore, 2D chirality was observed.

'Blue bubble' technique: an ab interno approach for Descemet separation in deep anterior lamellar keratoplasty using trypan blue stained viscoelastic device.

Science.gov (United States)

Livny, Eitan; Bahar, Irit; Hammel, Naama; Nahum, Yoav

2018-04-01

In this study, we examined a novel variant of 'big-bubble' deep anterior lamellar keratoplasty using trypan-blue-stained viscoelastic device for the creation of a pre-descemetic bubble. Ten corneoscleral rims were mounted on an artificial anterior chamber (AC). The AC was filled with air through a limbal paracentesis. A Melles' triangulated spatula was inserted through the paracentesis, with its tip penetrating the AC, was then slightly retracted and pushed into the deep stroma above the roof of the paracentesis. A mixture of trypan blue and viscoelastic device (Healon, Abbott Medical Optics, Abbott Park, Illinois) was injected into this intra-stromal pocket using a 27-G cannula to create a pre-descemetic separation bubble. Bubble type and visualization of dyed viscoelastic device were noted. The method was later employed in three cases. In all 10 corneoscleral rims, the technique successfully created a visible pre-descemetic (type 1) bubble that could be expanded up to the predicted diameter of trephination. Subsequent trephination and the removal of corneal stroma were uneventful. In two out of four clinical cases, a type 1 bubble was created, while in two others, visco-dissection failed and dyed viscoelastic was seen in the AC. The presented technique holds promise of being a relatively easy to perform, predictable and well-controlled alternative for achieving a type 1 bubble during deep anterior lamellar keratoplasty surgery. The trypan-blue-stained viscoelastic device facilitates proper visualization and control of the separation bubble and assists in identifying the penetrance to the separation bubble prior to removal of the stromal cap. © 2017 Royal Australian and New Zealand College of Ophthalmologists.

Influence of surface modified nanoilmenite/amorphous silica composite particles on the thermal stability of cold galvanizing coating

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A.M. Al-Sabagh

2018-03-01

Full Text Available The present approach investigates the use of novel nanoilmenite/amorphous silica composite (NI/AS particles fabricated from ilmenite nanoparticles (FeTiO3 NPs and synthesized amorphous silica grains to improve thermal stability of the cold galvanizing coating. Transmission electron microscopic (TEM images demonstrated that both nanoilmenite and nanocomposite particles were of flaky-like nature and the average diameter of the particles is 20 nm. The lamellar shape of the nanocomposite and spherical nature of Zn-dust particles were illustrated by scanning electron microscopy (SEM micrographs. Different alkyd-based cold galvanizing coating formulations were modified using uniformly dispersing various amounts of the processed nanocomposite particles as a modifier to form some engineering nanocomposite coatings. Thermal stability of the nanocomposite and Zn-dust particles was determined by thermo-gravimetric analysis (TGA. From the obtained results it could be observed that the weight loss (% as a feature of the thermal stability in case of the nanocomposite particles was 2.9 compared to 85.9 for Zn-dust powder grains. Derivative thermo-gravimetric (DTG measurements were done under nitrogen atmosphere for the cured cold galvanizing coating samples heated from room temperature to 1000 °C. The obtained results revealed that the maximum decomposition temperature point in the third degradation step for 6% nanocomposite surface modified cured sample (CG-F was detected at 693 °C and was less value for unmodified conventional cold galvanizing coating (CG-A at 612 °C. The increase in thermal stability with increasing the concentration of nanocomposite particles could be mainly attributed to the interface surface interaction between the nanocomposite particles and alkyd resin matrix in which enhancing the inorganic-organic network stiffness by causing a reduction in the total free spaces and enhancement in the cross-linking density of the cured film

Polymer brushes on nanoparticles: their positioning in and influence on block copolymer morphology.

Science.gov (United States)

Kim, Bumjoon

2007-03-01

Polymers brushes grafted to the nanoparticle surface enable the precise positioning of particles within a block copolymer matrix by determining the compatibility of nanoparticles within a polymeric matrix and modifying the interfacial properties between polymers and inorganic nanoparticle. Short thiol terminated polystyrene (PS-SH), poly(2-vinylpyridine) (P2VP-SH) and PS-r-P2VP with the molecular weight (Mn) of 3 kg/mol were used to control the location of Au nanoparticles over PS-b-P2VP diblock copolymer template. We will discuss further the approach of varying the areal chain density (σ) of PS-SH brushes on the PS coated particles, which utilizes the preferential wetting of one block of a copolymer (P2VP) on the Au substrate. Such favorable interaction provides the strong binding of Au particles to the PS/P2VP interface as σ of PS chains on the Au particle decreases. We find that at σ above a certain value, the nanoparticles are segregated to the center of the PS domains while below this value they are segregated to the interface. The transition σ for PS-SH chains (Mn = 3.4 kg/mol) is 1.3 chains/nm^2 but unexpectedly scales as Mn-0.55 as Mn is varied from 1.5 to 13 kg/mol. In addition, we will discuss changes in block copolymer morphology that occur as the nanoparticle volume fraction (φ) is increased for nanoparticles that segregate to the domain center as well as those that segregate to the interface, the latter behaving as nanoparticle surfactants. Small φ of such surfactants added to lamellar diblock copolymers lead initially to a decrease in lamellar thickness, a consequence of decreasing interfacial tension, up to a critical value of φ beyond which the block copolymer adopts a bicontinuous morphology. I thank my collaborators G. H. Fredrickson, J. Bang, C. J. Hawker, and E. J. Kramer as well as funding by the MRL as UCSB from the NSF-MRSEC-Program Award DMR05-20418.

Intrastromal Corneal Ring Segments for Astigmatism Correction after Deep Anterior Lamellar Keratoplasty

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Júlio C. D. Arantes

2017-01-01

Full Text Available Background. To evaluate the change in corneal astigmatism after intrastromal corneal ring segment (ICRS implantation in keratoconus patients with previous deep anterior lamellar keratoplasty (DALK. Design was a longitudinal, retrospective, interventional study. The study included 25 eyes of 24 patients with keratoconus who had DALK performed at least two years prior to ICRS implantation. All patients had a clear corneal graft with up to 8.00 D of corneal astigmatism and intolerance to contact lenses. The studied parameters were age, sex, corrected distance visual acuity (CDVA, maximum keratometry (K1, minimum keratometry (K2, spherical equivalent, and astigmatism. There was a statistically significant decrease in the postintervention analysis as follows: 3.5 D reduction in K1 (p<0.001; 1.53 D in K2 (p=0.005; and 2.52 D (p<0.001 in the average K. The spherical equivalent reduced from −3.67 D (±2.74 to −0.71 D (±2.35 (p<0.001. The topographic astigmatism reduced from 3.87 D preoperatively to 1.90 D postoperatively (p<0.001. The CDVA improved from 0.33 (±0.10 to 0.20 (±0.09, p<0.001. ICRS implantation is a useful option for the correction of astigmatism after DALK as it yields significant visual, topographic, and refractive results.

Infrared diffractive filtering for extreme ultraviolet multilayer Bragg reflectors

NARCIS (Netherlands)

Medvedev, Viacheslav; van den Boogaard, Toine; van der Meer, R.; Yakshin, Andrey; Louis, Eric; Krivtsun, V.M.; Bijkerk, Frederik

2013-01-01

Abstract: We report on the development of a hybrid mirror realized by integrating an EUV-reflecting multilayer coating with a lamellar grating substrate. This hybrid irror acts as an efficient Bragg reflector for extreme ultraviolet (EUV) radiation at a given wavelength while simultaneously

Effect of Substrate Friction in a Two-Dimensional Granular Couette Shearing Cell

Science.gov (United States)

Templeman, Chris; Garg, Shila

2001-03-01

An investigation of the effect of substrate friction on the kinematics of rigid granular material in a two-dimensional granular Couette shearing cell was conducted. Cylindrical disks resting on a substrate were packed between a stationary outer ring and a rotating inner wheel. Previous work reports the velocity and particle rotation rates as a function of packing fraction and shearing rates [1]. The authors report the existence of a stick-slip condition of the disks in contact with the shearing wheel. The focus of our study is to investigate the impact of the substrate friction on the stick-slip condition as well as the kinematics of the system in general. [1] C.T. Veje, Daniel W. Howell, and R.P Behringer, Phys. Rev. E 59, 739 (1999). This research was partially supported by the Copeland Fund, administered by The College of Wooster. C.T. received support from NASA GRC LERCIP internship program.

Influence of Substrate Biasing on (Ba,Sr)TiO3 Films Prepared by Electron Cyclotron Resonance Plasma Sputtering

Science.gov (United States)

Matsumoto, Takeshi; Niino, Atsushi; Ohtsu, Yasunori; Misawa, Tatsuya; Yonesu, Akira; Fujita, Hiroharu; Miyake, Shoji

2004-03-01

(Ba,Sr)TiO3 (BST) films were deposited by electron cyclotron resonance (ECR) plasma sputtering with mirror confinement. DC bias voltage was applied to Pt/Ti/SiO2/Si substrates during deposition to vary the intensity of bombardment of energetic ions and to modify film properties. BST films deposited on the substrates at floating potential (approximately +20 V) were found to be amorphous, while films deposited on +40 V-biased substrates were crystalline in spite of a low substrate temperature below 648 K. In addition, atomic diffusion, which causes deterioration in the electrical properties of the films, was hardly observed in the crystallized films deposited with +40 V bias perhaps due to the low substrate temperature. Plasma diagnoses revealed that application of a positive bias to the substrate reduced the energy of ion bombardment and increased the density of excited neutral particles, which was assumed to result in the promotion of chemical reactions during deposition and the crystallization of BST films at a low temperature.

Structural investigation of ZnO:Al films deposited on the Si substrates by radio frequency magnetron sputtering

International Nuclear Information System (INIS)

Chen, Y.Y.; Yang, J.R.; Cheng, S.L.; Shiojiri, M.

2013-01-01

ZnO:Al films 400 nm thick were prepared on (100) Si substrates by magnetron sputtering. Energy dispersive X-ray spectroscopy and transmission electron microscopy (TEM) revealed that in the initial stage of the deposition, an amorphous silicon oxide layer about 4 nm thick formed from damage to the Si substrate due to sputtered particle bombardment and the incorporation of Si atoms with oxygen. Subsequently, a crystalline Si (Zn) layer about 30 nm thick grew on the silicon oxide layer by co-deposition of Si atoms sputtered away from the substrate with Zn atoms from the target. Finally, a ZnO:Al film with columnar grains was deposited on the Si (Zn) layer. The sputtered particle bombardment greatly influenced the structure of the object films. The (0001) lattice fringes of the ZnO:Al film were observed in high-resolution TEM images, and the forbidden 0001 reflection spots in electron diffraction patterns were attributed to double diffraction. Therefore, the appearance of the forbidden reflection did not imply any ordering of Al atoms and/or O vacancies in the ZnO:Al film. - Highlights: • ZnO:Al films were deposited on (100) Si substrate using magnetron sputtering. • An amorphous silicon oxide layer with a thickness of 4 nm was formed on Si substrate. • Crystalline Si (Zn) layer about 30 nm thick grew on amorphous silicon oxide layer. • ZnO:Al film comprising columnar grains was deposited on the Si(Zn) layer. • Lattice image of the ZnO:Al film has been interpreted

Particles on surfaces of laser ablated Y{sub 1}Ba{sub 2}Cu{sub 3}O{sub 7-{delta}} films

Energy Technology Data Exchange (ETDEWEB)

Zheng, X.Y.; Zhu, S. [Tennessee Univ., Knoxville, TN (United States); Lowndes, D.H.; Warmack, R.J. [Oak Ridge National Lab., TN (United States)

1993-09-01

Pulsed laser deposition of Y{sub 1}Ba{sub 2}Cu{sub 3}O{sub 7-{delta}} films grown at heater temperature of 720 and 800 C on SrTiO{sub 3} and MgO substrates with thickness ranging from a nominal 5 unit cells to 200 nm were studied by STM and SEM. Size and density of particles present in the films were found to depend on film thickness, growth temperature and substrate. STM images indicate a correlation between film growth mode and particle density: the onset of big particles comes after the growth mode changes from layer-like to island growth.

Electrical Field Guided Electrospray Deposition for Production of Gradient Particle Patterns.

Science.gov (United States)

Yan, Wei-Cheng; Xie, Jingwei; Wang, Chi-Hwa

2018-06-06

Our previous work demonstrated the uniform particle pattern formation on the substrates using electrical field guided electrospray deposition. In this work, we reported for the first time the fabrication of gradient particle patterns on glass slides using an additional point, line, or bar electrode based on our previous electrospray deposition configuration. We also demonstrated that the polydimethylsiloxane (PDMS) coating could result in the formation of uniform particle patterns instead of gradient particle patterns on glass slides using the same experimental setup. Meanwhile, we investigated the effect of experimental configurations on the gradient particle pattern formation by computational simulation. The simulation results are in line with experimental observations. The formation of gradient particle patterns was ascribed to the gradient of electric field and the corresponding focusing effect. Cell patterns can be formed on the particle patterns deposited on PDMS-coated glass slides. The formed particle patterns hold great promise for high-throughput screening of biomaterial-cell interactions and sensing.

Improved osteoblasts growth on osteomimetic hydroxyapatite/BaTiO{sub 3} composites with aligned lamellar porous structure

Energy Technology Data Exchange (ETDEWEB)

Liu, Beilei [Department of Stomatology, Third Xiangya Hospital, Central South University, Changsha, Hunan 410013 (China); Chen, Liangjian, E-mail: jian007040@sina.com [Department of Stomatology, Third Xiangya Hospital, Central South University, Changsha, Hunan 410013 (China); State Key Laboratory of Powder Metallurgy, Central South University, Changsha, Hunan 410083 (China); Shao, Chunsheng [Department of Stomatology, Third Xiangya Hospital, Central South University, Changsha, Hunan 410013 (China); Zhang, Fuqiang; Zhou, Kechao [State Key Laboratory of Powder Metallurgy, Central South University, Changsha, Hunan 410083 (China); Cao, Jun [Department of Stomatology, Third Xiangya Hospital, Central South University, Changsha, Hunan 410013 (China); Zhang, Dou, E-mail: dzhang@csu.edu.cn [State Key Laboratory of Powder Metallurgy, Central South University, Changsha, Hunan 410083 (China)

2016-04-01

Osteoblasts growing into bone substitute is an important step of bone regeneration. This study prepared porous hydroxyapatite (HA)/BaTiO{sub 3} piezoelectric composites with porosity of 40%, 50% and 60% by ice-templating method. Effects of HA/BaTiO{sub 3} composites with different porosities, with and without polarizing treatment on adhesion, proliferation and differentiation of osteoblasts were investigated in vitro. Results revealed that cell densities of the porous groups were significantly higher than those of the dense group (p < 0.05), so did the alkaline phosphate (ALP) and bone gla protein (BGP) activities. Porosity of 50% group exhibited higher ALP activity and BGP activity than those of the 40% and 60% groups. Scanning electron microscopy (SEM) observations revealed that osteoblasts adhered and stretched better on porous HA/BaTiO{sub 3} than on the dense one, especially HA/BaTiO{sub 3} with porosity of 50% and 60%. However, there was no significant difference in the cell morphology, cell densities, ALP and BGP activities between the polarized group and the non-polarized group (p > 0.05). The absence of mechanical loading on the polarized samples may account for this. The results indicated that hierarchically porous HA/BaTiO{sub 3} played a favorable part in osteoblasts proliferation, differentiation and adhesion process and is a promising bone substitute material. - Graphical abstract: Aligned porous structure of HA/BaTiO{sub 3} piezoelectric composites prepared by ice-templating method was similar to the lamellar Haversian system in bone tissue. When co-cultured with human osteosarcoma cells (MG63), porous HA/BaTiO{sub 3} composites exhibited remarkable biological activity in promoting proliferation, differentiation and adhesion of MG63 cells. - Highlights: • The aligned porous structure of HA/BaTiO{sub 3} composite was similar to the lamellar Haversian system in bone tissue. • The piezoelectric d{sub 33} coefficient of HA/BaTiO{sub 3} with porosity

Modeling and simulation of viscoelastic biological particles' 3D manipulation using atomic force microscopy

Science.gov (United States)

Korayem, M. H.; Habibi Sooha, Y.; Rastegar, Z.

2018-05-01

Manipulation of the biological particles by atomic force microscopy is used to transfer these particles inside body's cells, diagnosis and destruction of the cancer cells and drug delivery to damaged cells. According to the impossibility of simultaneous observation of this process, the importance of modeling and simulation can be realized. The contact of the tip with biological particle is important during manipulation, therefore, the first step of the modeling is choosing appropriate contact model. Most of the studies about contact between atomic force microscopy and biological particles, consider the biological particle as an elastic material. This is not an appropriate assumption because biological cells are basically soft and this assumption ignores loading history. In this paper, elastic and viscoelastic JKR theories were used in modeling and simulation of the 3D manipulation for three modes of tip-particle sliding, particle-substrate sliding and particle-substrate rolling. Results showed that critical force and time in motion modes (sliding and rolling) for two elastic and viscoelastic states are very close but these magnitudes were lower in the viscoelastic state. Then, three friction models, Coulomb, LuGre and HK, were used for tip-particle sliding mode in the first phase of manipulation to make results closer to reality. In both Coulomb and LuGre models, critical force and time are very close for elastic and viscoelastic states but in general critical force and time prediction of HK model was higher than LuGre and the LuGre model itself had higher prediction than Coulomb.

Rebound mechanics of micrometre-scale, spherical particles in high-velocity impacts.

Science.gov (United States)

Yildirim, Baran; Yang, Hankang; Gouldstone, Andrew; Müftü, Sinan

2017-08-01

The impact mechanics of micrometre-scale metal particles with flat metal surfaces is investigated for high-velocity impacts ranging from 50 m s -1 to more than 1 km s -1 , where impact causes predominantly plastic deformation. A material model that includes high strain rate and temperature effects on the yield stress, heat generation due to plasticity, material damage due to excessive plastic strain and heat transfer is used in the numerical analysis. The coefficient of restitution e is predicted by the classical work using elastic-plastic deformation analysis with quasi-static impact mechanics to be proportional to [Formula: see text] and [Formula: see text] for the low and moderate impact velocities that span the ranges of 0-10 and 10-100 m s -1 , respectively. In the elastic-plastic and fully plastic deformation regimes the particle rebound is attributed to the elastic spring-back that initiates at the particle-substrate interface. At higher impact velocities (0.1-1 km s -1 ) e is shown to be proportional to approximately [Formula: see text]. In this deeply plastic deformation regime various deformation modes that depend on plastic flow of the material including the time lag between the rebound instances of the top and bottom points of particle and the lateral spreading of the particle are identified. In this deformation regime, the elastic spring-back initiates subsurface, in the substrate.

Determination of the influence of C24 D/(2R)- and L/(2S)-isomers of the CER[AP] on the lamellar structure of stratum corneum model systems using neutron diffraction.

Science.gov (United States)

Schmitt, Thomas; Lange, Stefan; Sonnenberger, Stefan; Dobner, Bodo; Demé, Bruno; Neubert, Reinhard H H; Gooris, Gert; Bouwstra, Joke A

2017-12-01

This study was able to investigate the different influence of the d- and l-ceramide [AP] on the lamellar as well as molecular nanostructure of stratum corneum simulating lipid model mixtures. In this case, neutron diffraction together with specifically deuterated ceramide was used as an effective tool to investigate the lamellar and the molecular nanostructure of the mixtures. It could clearly be demonstrated, that both isomers show distinctly different characteristics, even though the variation between both is only a single differently arranged OH-group. The l-ceramide [AP] promotes a crystalline like phase behaviour even if mixed with ceramide [NP], cholesterol and free fatty acids. The d-ceramide [AP] only shows crystalline-like features if mixed only with cholesterol and free fatty acids but adopts a native-like behaviour if additionally mixed with ceramide [NP]. It furthermore demonstrates that the l-ceramide [AP] should not be used for any applications concerning ceramide substitution. It could however possibly serve its own purpose, if this crystalline like behaviour has some kind of positive influence on the SC or can be utilized for any practical applications. The results obtained in this study demonstrate that the diastereomers of ceramide [AP] are an attractive target for further research because their influence on the lamellar as well as the nanostructure is exceptionally strong. Additionally, the results furthermore show a very strong influence on hydration of the model membrane. With these properties, the d-ceramide [AP] could be effectively used to simulate native like behaviour even in very simple mixtures and could also have a strong impact on the native stratum corneum as well as high relevance for dermal ceramide substitution. The unnatural l-ceramide [AP] on the other hand should be investigated further, to assess its applicability. Copyright © 2017 Elsevier B.V. All rights reserved.

Intrinsic kinetic parameters of substrate utilization by immobilized anaerobic sludge.

Science.gov (United States)

Zaiat, M; Vieira, L G; Foresti, E

1997-01-20

This article presents a method for evaluating the intrinsic kinetic parameters of the specific substrate utilization rate (r) equation and discusses the results obtained for anaerobic sludge-bed samples taken from a horizontal-flow anaerobic immobilized sludge (HAIS) reactor. This method utilizes a differential reactor filled with polyurethane foam matrices containing immobilized anaerobic sludge which is subjected to a range of feeding substrate flow rates. The range of liquid superficial velocities thus obtained are used for generating data of observed specific substrate utilization rates (r(obs)) under a diversity of external mass transfer resistance conditions. The r(obs) curves are then adjusted to permit their extrapolation for the condition of no external mass transfer resistance, and the values determined are used as a test for the condition of absence of limitation of internal mass transfer. The intrinsic parameters r(max), the maximum specific substrate utilization rate, and K(s), the half-velocity coefficient, are evaluated from the r values under no external mass transfer resistance and no internal mass transfer limitation. The application of such a method for anaerobic sludge immobilized in polyurethane foam particles treating a glucose substrate at 30 degrees C resulted in intrinsic r(max) and K(s), respectively, of 0.330 mg chemical oxygen demand (COD) . mg(-1) volatile suspended solids (VSS) . h(-1) and 72 mg COD . L(-1). In comparison with the values found in the literature, intrinsic r(max) is significantly high and intrinsic K(s) is relatively low. (c) 1997 John Wiley & Sons, Inc.

Wettability of eutectic NaLiCO3 salt on magnesium oxide substrates at 778 K

Science.gov (United States)

Li, Chuan; Li, Qi; Cao, Hui; Leng, Guanghui; Li, Yongliang; Wang, Li; Zheng, Lifang; Ding, Yulong

2018-06-01

We investigated the wetting behavior of a eutectic carbonate salt of NaLiCO3 on MgO substrates at an elevated temperature of 778 K by measuring contact angle with a sessile drop method. Both sintered and non-sintered MgO were prepared and used as the substrates. The sintered substrates were obtained by sintering compacted MgO powders at 500-1300 °C. For comparison purposes, a single crystal MgO substrate was also used in the work. The different sintering temperatures provided MgO substrates with different structures, allowing their effects on salt penetration and hence wettability and surface energy to be investigated. A scanning electron microscope equipped with energy dispersive spectrometry and an atomic force microscope were used to observe the morphology and structures of the MgO substrates as well as the salt penetration. The results showed a good wettability of the carbonate salt on both the sintered and non-sintered MgO substrates and the wettability depended strongly on the structure of the substrates. The non-sintered MgO substrate has a loose surface particle packing with large pores and crevices, leading to significant salt infiltration, and the corresponding contact angle was measured to be ∼25°. The contact angle of the salt on the sintered MgO substrates increased with an increase in the sintering temperature of the MgO substrate, and the contact angle of the salt on the single crystal substrate was the highest at ∼40°. The effect of the sintering temperature for making the MgO substrate could be linked to the surface energy, and the linkage is validated by the AFM measurements of the adhesion forces of the MgO substrates.

Lamellar boundary alignment of DS-processed TiAl-W alloys by a solidification procedure

Science.gov (United States)

Jung, In-Soo; Oh, Myung-Hoon; Park, No-Jin; Kumar, K. Sharvan; Wee, Dang-Moon

2007-12-01

In this study, a β solidification procedure was used to align the lamellae in a Ti-47Al-2W (at.%) alloy parallel to the growth direction. The Bridgman technique and the floating zone process were used for directional solidification. The mechanical properties of the directionally solidified alloy were evaluated in tension at room temperature and at 800°C. At a growth rate of 30 mm/h (with the floating zone approach), the lamellae were well aligned parallel to the growth direction. The aligned lamellae yielded excellent room temperature tensile ductility. The tensile yield strength at 800°C was similar to that at room temperature. The orientation of the γ lamellar laths in the directionally solidified ingots, which were manufactured by means of a floating zone process, was identified with the aid of electron backscattered diffraction analysis. On the basis of this analysis, the preferred growth direction of the bcc-β dendrites that formed at high temperatures close to the melting point was inferred to be [001]β at a growth rate of 30 mm/h and [111]β at a growth rate of 90 mm/h.

Preparation of Superhydrophobic Film on Ti Substrate and Its Anticorrosion Property.

Science.gov (United States)

Zhu, Min; Tang, Wenchuan; Huang, Luyao; Zhang, Dawei; Du, Cuiwei; Yu, Gaohong; Chen, Ming; Chowwanonthapunya, Thee

2017-06-08

Superhydrophobic films were fabricated on a titanium substrate with or without anodizing by using a self-assembling method. Firstly, the pretreatments of mechanical polishing/anodizing or mechanical polishing only were conducted, respectively. Subsequently, the preparation of polydopamine film layer, deposition of nano-silver particles, and post modification of 1H,1H,2H,2H-perfluorodecanethiol were performed on the surface of the pretreated substrate. The surface morphologies, compositions, wettability, and corrosion resistance of the films were investigated with scanning electron microscopy (SEM), energy-dispersive spectrometry (EDS), water contact angle measurements, and electrochemical tests, respectively. Meanwhile, the effect of the deposition time in the silver nitrate solution on the hydrophobicity of the specimen surface was investigated. The result showed that with the increase of deposition time, the hydrophobic property enhanced gradually. The surface deposited for 7 h exhibited an optimum hydrophobic effect, which was characterized with a large water contact angle (WCA) of 154°, and the surface was rather rough and covered by a relatively uniform layer of micro-nano silver particles. The excellent hydrophobicity was attributed to a rough stratified microstructure along with the low surface energy. The electrochemical measurements showed that the existence of the superhydrophobic film can effectively enhance the corrosion resistance of Ti samples.

Metallization and biopatterning on ultra-flexible substrates via dextran sacrificial layers.

Directory of Open Access Journals (Sweden)

Peter Tseng

Full Text Available Micro-patterning tools adopted from the semiconductor industry have mostly been optimized to pattern features onto rigid silicon and glass substrates, however, recently the need to pattern on soft substrates has been identified in simulating cellular environments or developing flexible biosensors. We present a simple method of introducing a variety of patterned materials and structures into ultra-flexible polydimethylsiloxane (PDMS layers (elastic moduli down to 3 kPa utilizing water-soluble dextran sacrificial thin films. Dextran films provided a stable template for photolithography, metal deposition, particle adsorption, and protein stamping. These materials and structures (including dextran itself were then readily transferrable to an elastomer surface following PDMS (10 to 70∶1 base to crosslinker ratios curing over the patterned dextran layer and after sacrificial etch of the dextran in water. We demonstrate that this simple and straightforward approach can controllably manipulate surface wetting and protein adsorption characteristics of PDMS, covalently link protein patterns for stable cell patterning, generate composite structures of epoxy or particles for study of cell mechanical response, and stably integrate certain metals with use of vinyl molecular adhesives. This method is compatible over the complete moduli range of PDMS, and potentially generalizable over a host of additional micro- and nano-structures and materials.

Metallization and Biopatterning on Ultra-Flexible Substrates via Dextran Sacrificial Layers

Science.gov (United States)

Tseng, Peter; Pushkarsky, Ivan; Di Carlo, Dino

2014-01-01

Micro-patterning tools adopted from the semiconductor industry have mostly been optimized to pattern features onto rigid silicon and glass substrates, however, recently the need to pattern on soft substrates has been identified in simulating cellular environments or developing flexible biosensors. We present a simple method of introducing a variety of patterned materials and structures into ultra-flexible polydimethylsiloxane (PDMS) layers (elastic moduli down to 3 kPa) utilizing water-soluble dextran sacrificial thin films. Dextran films provided a stable template for photolithography, metal deposition, particle adsorption, and protein stamping. These materials and structures (including dextran itself) were then readily transferrable to an elastomer surface following PDMS (10 to 70∶1 base to crosslinker ratios) curing over the patterned dextran layer and after sacrificial etch of the dextran in water. We demonstrate that this simple and straightforward approach can controllably manipulate surface wetting and protein adsorption characteristics of PDMS, covalently link protein patterns for stable cell patterning, generate composite structures of epoxy or particles for study of cell mechanical response, and stably integrate certain metals with use of vinyl molecular adhesives. This method is compatible over the complete moduli range of PDMS, and potentially generalizable over a host of additional micro- and nano-structures and materials. PMID:25153326

Preparation of Superhydrophobic Film on Ti Substrate and Its Anticorrosion Property

Directory of Open Access Journals (Sweden)

Min Zhu

2017-06-01

Full Text Available Superhydrophobic films were fabricated on a titanium substrate with or without anodizing by using a self-assembling method. Firstly, the pretreatments of mechanical polishing/anodizing or mechanical polishing only were conducted, respectively. Subsequently, the preparation of polydopamine film layer, deposition of nano-silver particles, and post modification of 1H,1H,2H,2H-perfluorodecanethiol were performed on the surface of the pretreated substrate. The surface morphologies, compositions, wettability, and corrosion resistance of the films were investigated with scanning electron microscopy (SEM, energy-dispersive spectrometry (EDS, water contact angle measurements, and electrochemical tests, respectively. Meanwhile, the effect of the deposition time in the silver nitrate solution on the hydrophobicity of the specimen surface was investigated. The result showed that with the increase of deposition time, the hydrophobic property enhanced gradually. The surface deposited for 7 h exhibited an optimum hydrophobic effect, which was characterized with a large water contact angle (WCA of 154°, and the surface was rather rough and covered by a relatively uniform layer of micro-nano silver particles. The excellent hydrophobicity was attributed to a rough stratified microstructure along with the low surface energy. The electrochemical measurements showed that the existence of the superhydrophobic film can effectively enhance the corrosion resistance of Ti samples.

Preparation of Superhydrophobic Film on Ti Substrate and Its Anticorrosion Property

Science.gov (United States)

Zhu, Min; Tang, Wenchuan; Huang, Luyao; Zhang, Dawei; Du, Cuiwei; Yu, Gaohong; Chen, Ming; Chowwanonthapunya, Thee

2017-01-01

Superhydrophobic films were fabricated on a titanium substrate with or without anodizing by using a self-assembling method. Firstly, the pretreatments of mechanical polishing/anodizing or mechanical polishing only were conducted, respectively. Subsequently, the preparation of polydopamine film layer, deposition of nano-silver particles, and post modification of 1H,1H,2H,2H-perfluorodecanethiol were performed on the surface of the pretreated substrate. The surface morphologies, compositions, wettability, and corrosion resistance of the films were investigated with scanning electron microscopy (SEM), energy-dispersive spectrometry (EDS), water contact angle measurements, and electrochemical tests, respectively. Meanwhile, the effect of the deposition time in the silver nitrate solution on the hydrophobicity of the specimen surface was investigated. The result showed that with the increase of deposition time, the hydrophobic property enhanced gradually. The surface deposited for 7 h exhibited an optimum hydrophobic effect, which was characterized with a large water contact angle (WCA) of 154°, and the surface was rather rough and covered by a relatively uniform layer of micro-nano silver particles. The excellent hydrophobicity was attributed to a rough stratified microstructure along with the low surface energy. The electrochemical measurements showed that the existence of the superhydrophobic film can effectively enhance the corrosion resistance of Ti samples. PMID:28772987

Simultaneous evaluation of effective diffusion coefficients of the substrates in a biofilm with a novel experimental method

Energy Technology Data Exchange (ETDEWEB)

Beyenal, H.; Tanyolac, A. [Hacettepe Univ., Ankara (Turkey)

1996-08-01

A pure culture of Zoogloea ramigera was grown as a film on active carbon particles in a differential fluidized bed biofilm reactor. Pseudo-steady state conditions were established within this reactor and thus, the stable substrate concentrations and flux values were obtained within definite time intervals, along with homogeneous biofilm thickness and density. The free-growth kinetics of the culture were studied in a continuous fermenter and a multi-substrate growth model was used to describe the utilization of limiting substrate in the biofilm. The limiting substrates for the culture were determined to be glucose, ammonium and oxygen. The effective diffusion coefficients of these substrates were calculated simultaneously with a diffusion-reaction model. Results of the model solution revealed that the effective diffusion coefficient for all three substrates through the biofilm decreased with increased biofilm density and observed biofilm thickness up to a critical value of about 90 x 10{sup -6} m. After this critical point, all diffusion coefficients started to increase slowly due to diminished biofilm density. 31 refs., 4 figs., 4 tabs.

Mixtures of organic and inorganic substrates, particle size and proportion

International Nuclear Information System (INIS)

Morales-Maldonado, Emilio Raymundo; Casanova-Lugo, Fernando

2015-01-01

The mixtures of organic and inorganic materials used in the preparation of a new material, particle size, proportion and their response in plant were reviewed. Agricultural wastes are considered a pollutant reservoir in Mexico; however, for another perspective this represent an industry with great potential. The nutrients ingested by animals represent nutriments available for plants when properly recycled. The production of compost and vermicompost is an option that minimize the risk of contamination and improve quality. Both processes are an alternative for organic production. The efficiency of irrigation and fertilization are affected for the reducing the volumen of an organic material incresase compaction and compression of roots. The mixtures with inorganic materials are used in the development of a new material to obtain better growing conditions for the plant. (author) [es

Alignment of SWNTs by protein-ligand interaction of functionalized magnetic particles under low magnetic fields.

Science.gov (United States)

Park, Tae Jung; Park, Jong Pil; Lee, Seok Jae; Jung, Dae-Hwan; Ko, Young Koan; Jung, Hee-Tae; Lee, Sang Yup

2011-05-01

Carbon nanotubes (CNTs) have attracted considerable attention for applications using their superior mechanical, thermal and electrical properties. A simple method to controllably align single-walled CNTs (SWNTs) by using magnetic particles embedded with superparamagnetic iron oxide as an accelerator under the magnetic field was developed. The functionalization of SWNTs using biotin, interacted with streptavidin-coupled magnetic particles (micro-to-nano in diameter), and layer-by-layer assembly were performed for the alignment of a particular direction onto the clean silicon and the gold substrate at very low magnetic forces (0.02-0.89 T) at room temperature. The successful alignment of the SWNTs with multi-layer film was observed by scanning electron microscopy (SEM) and transmission electron microscopy (TEM). By changing the orientation and location of the substrates, crossed-networks of SWNTs-magnetic particle complex could easily be fabricated. We suggest that this approach, which consists of a combination of biological interaction among streptavidin-biotin and magnetite particles, should be useful for lateral orientation of individual SWNTs with controllable direction.

A comparative review between the updated models of Brazilian, United Kingdom and American eye banks and lamellar transplants

Directory of Open Access Journals (Sweden)

Gustavo Victor

2014-12-01

Full Text Available The corneal transplantation (CT is the most commonly performed type of transplant in the world and the Eye Banks are organizations whose capture, evaluate, preserve, store and distribute ocular tissues. With the evolution of surgical techniques and equipment for CT, the BOs had to evolve to keep up with these requirements. This evolution goes from tissues capture techniques, donating money and clarification to the patient (e.g. internet-based, use of current equipment for more adequate tissues supply for the most current surgical techniques, integration of BOs of certain country and real-time management of stocks of ocular tissues, and adequacy of laws that manage the entire process. This review aims to make a comparative review between the updated models of Brazilian, United Kingdon and American Eye Banks. Like, check what the trend towards lamellar transplants in these three countries.

Tribological Properties of Aluminum Alloy treated by Fine Particle Peening/DLC Hybrid Surface Modification

Directory of Open Access Journals (Sweden)

Nanbu H.

2010-06-01

Full Text Available In order to improve the adhesiveness of the DLC coating, Fine Particle Peening (FPP treatment was employed as pre-treatment of the DLC coating process. FPP treatment was performed using SiC shot particles, and then AA6061-T6 aluminum alloy was DLC-coated. A SiC-rich layer was formed around the surface of the aluminum alloy by the FPP treatment because small chips of shot particles were embedded into the substrate surface. Reciprocating sliding tests were conducted to measure the friction coefficients. While the DLC coated specimen without FPP treatment showed a sudden increase in friction coefficient at the early stage of the wear cycles, the FPP/DLC hybrid treated specimen maintained a low friction coefficient value during the test period. Further investigation revealed that the tribological properties of the substrate after the DLC coating were improved with an increase in the amount of Si at the surface.

Spatially Mapping Energy Transfer from Single Plasmonic Particles to Semiconductor Substrates via STEM/EELS.

Science.gov (United States)

Li, Guoliang; Cherqui, Charles; Bigelow, Nicholas W; Duscher, Gerd; Straney, Patrick J; Millstone, Jill E; Masiello, David J; Camden, Jon P

2015-05-13

Energy transfer from plasmonic nanoparticles to semiconductors can expand the available spectrum of solar energy-harvesting devices. Here, we spatially and spectrally resolve the interaction between single Ag nanocubes with insulating and semiconducting substrates using electron energy-loss spectroscopy, electrodynamics simulations, and extended plasmon hybridization theory. Our results illustrate a new way to characterize plasmon-semiconductor energy transfer at the nanoscale and bear impact upon the design of next-generation solar energy-harvesting devices.

The Type of Forage Substrate Preparation Included as Substrate in a RUSITEC System Affects the Ruminal Microbiota and Fermentation Characteristics

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Alexandre V. Chaves

2017-04-01

Full Text Available In vitro fermentation systems such as the rumen simulation technique (RUSITEC are frequently used to assess dietary manipulations in livestock, thereby limiting the use of live animals. Despite being in use for nearly 40 years, improvements are continually sought in these systems to better reflect and mimic natural processes in ruminants. The aim of this study was to evaluate the effect of forage preparation, i.e., frozen minced (FM and freeze-dried and ground (FDG, on the ruminal microbiota and on fermentation characteristics when included as a substrate in a RUSITEC system. A completely randomized design experiment was performed over a 15-day period, with 7 days of adaptation and an 8-day experimental period. Fermentation parameters (total gas, CH4, and volatile fatty acid production were analyzed on a daily basis over the experimental period and the archaeal and bacterial microbiota (liquid-associated microbes [LAM] and solid-associated microbes [SAM] was assessed at 0, 5, 10, and 15 days using high-throughput sequencing of the 16S rRNA gene. Results from this study suggested a tendency (P = 0.09 of FM treatment to increase daily CH4 (mg/d production by 16.7% when compared with FDG treatment. Of the major volatile fatty acids (acetate, propionate, and butyrate, only butyrate production was greater (P = 0.01 with FM treatment compared with FDG substrate. The archaeal and bacterial diversity and richness did not differ between the forage preparations, although feed particle size of the forage had a significant effect on microbial community structure in the SAM and LAM samples. The Bacteroidetes phylum was more relatively abundant in the FM substrate treatment, while Proteobacteria was enriched in the FDG treatment. At the genus-level, Butyrivibrio, Prevotella, and Roseburia were enriched in the FM substrate treatment and Campylobacter and Lactobacillus in the FDG substrate treatment. Evidence from this study suggests that forage preparation

Microstructure of a Ni Matrix Composite Coating Reinforced by In-situ TiC Particles Using Plasma Cladding

Institute of Scientific and Technical Information of China (English)

WUYu-ping; WANGZe-hua; LINPing-hua

2004-01-01

Plasma cladding process was used to prepare the TiC/Ni composite coating on the mild steel substrates. The TiC particles were synthesized in-situ. Microstructure and properties of the coating were investigated by optical microscopy, X-Ray diffraction, SEM, TEM and microhardness tester. The results show that the interface between the coating and the substrate is metallurgically bonded. The coating was uniform and almost defect-free when [Ti+C] varied from 10% to 20% after ball milling. The microstructure of the coating is mainly composed of γ-Ni dendrite, interdendritic eutectic (γ-Ni austenite, M23C6 and CrB) and TiC particles. Most of the TiC particles are spherical and a small fraction is blocky in size of 1-2μm. The TiC particles are smaller at the bottom than near the top of the coating. The coating has a gradient microstructure and a highest hardness of 1000Hv0.1.

Graphene frameworks synthetized with Na2CO3 as a renewable water-soluble substrate and their high rate capability for supercapacitors

Science.gov (United States)

Cui, Huijuan; Zheng, Jianfeng; Zhu, Yanyan; Wang, Zhijian; Jia, Suping; Zhu, Zhenping

2015-10-01

Substrates are normally required in the chemical synthesis of graphene to enhance its formation. However, removing substrates in the post purification stage is difficult, during which harsh reagents are used and the substrates are usually consumed undesirably. In this paper, we report that universal sodium carbonate (Na2CO3) particles can effectively promote the construction of well-structured graphene frameworks based on a quick thermal decomposition of fumaric acids. Notably, the Na2CO3 particles are easily separated from graphene through a simple and green method, namely, washing with water at room temperature. Together with the reused characteristic of the recovered Na2CO3 particles, this approach is undoubtedly beneficial to the low-cost and clean synthesis of graphene. Benefiting from the framework structure, the as-synthesized graphene exhibits excellent performance in the supercapacitor. The specific capacitance of the GFs-modified electrode was calculated to be 242 F g-1 at 0.5 A g-1, which was almost twice that of the RGO-modified electrode (134 F g-1). More importantly, the GFs-modified electrode maintained 92.6% retention of its initial specific capacitance (from current density of 0.5 to 16 A g-1), which was much higher than that of 2D graphene-modified electrode.

Diamond knife-assisted deep anterior lamellar keratoplasty to manage keratoconus.

Science.gov (United States)

Vajpayee, Rasik B; Maharana, Prafulla K; Sharma, Namrata; Agarwal, Tushar; Jhanji, Vishal

2014-02-01

To evaluate the outcomes of a new surgical technique, diamond knife-assisted deep anterior lamellar keratoplasty (DALK), and compare its visual and refractive results with big-bubble DALK in cases of keratoconus. Tertiary eyecare hospital. Comparative case series. The visual and surgical outcomes of diamond knife-assisted DALK were compared with those of successful big-bubble DALK. Diamond knife-assisted DALK was performed in 19 eyes and big-bubble DALK, in 11 eyes. All surgeries were completed successfully. No intraoperative or postoperative complications occurred with diamond knife-assisted DALK. Six months after diamond knife-assisted DALK, the mean corrected distance visual acuity (CDVA) improved significantly from 1.87 logMAR ± 0.22 (SD) to 0.23 ± 0.06 logMAR, the mean keratometry improved from 65.99 ± 8.86 diopters (D) to 45.13 ± 1.16 D, and the mean keratometric cylinder improved from 7.99 ± 3.81 D to 2.87 ± 0.59 D (all P=.005). Postoperatively, the mean refractive astigmatism was 2.55 ± 0.49 D and the mean spherical equivalent was -1.97 ± 0.56 D. The mean logMAR CDVA (P = .06), postoperative keratometry (P=.64), refractive cylinder (P=.63), and endothelial cell loss (P=.11) were comparable between diamond knife-assisted DALK and big-bubble DALK. Diamond knife-assisted DALK was effective and predictable as a surgical technique for management of keratoconus cases. This technique has the potential to offer visual and refractive outcomes comparable to those of big-bubble DALK. No author has a financial or proprietary interest in any material or method mentioned. Copyright © 2013 ASCRS and ESCRS. Published by Elsevier Inc. All rights reserved.

Spatial confinement governs orientational order in patchy particles

Science.gov (United States)

Iwashita, Yasutaka; Kimura, Yasuyuki

2016-06-01

Orientational order in condensed matter plays a key role in determining material properties such as ferromagnetism, viscoelasticity or birefringence. We studied purely orientational ordering in closely-packed one-patch colloidal particles confined between flat substrates, where the particles can only rotate and are ordered via the sticky interaction between the patches. For the first time, we experimentally realized a rich variety of mesoscopic patterns through orientational ordering of colloids by controlling patch size and confinement thickness. The combination of experiment and numerical simulation reveals the decisive role of confinement: An ordered state(s) is selected from the (meta)stable options in bulk when it is commensurate with the system geometry and boundary conditions; otherwise, frustration induces a unique order. Our study offers a new means of systematic control over mesoscopic structures via orientational ordering in patchy particles. The system would also possess unique functionalities through the rotational response of the particles to external stimuli.

Virus-like particle production with yeast: ultrastructural and immunocytochemical insights into Pichia pastoris producing high levels of the Hepatitis B surface antigen

Directory of Open Access Journals (Sweden)

Adnan Ahmad

2011-06-01

Full Text Available Abstract Background A protective immune response against Hepatitis B infection can be obtained through the administration of a single viral polypeptide, the Hepatitis B surface antigen (HBsAg. Thus, the Hepatitis B vaccine is generated through the utilization of recombinant DNA technology, preferentially by using yeast-based expression systems. However, the polypeptide needs to assemble into spherical particles, so-called virus-like particles (VLPs, to elicit the required protective immune response. So far, no clear evidence has been presented showing whether HBsAg assembles in vivo inside the yeast cell into VLPs or later in vitro during down-stream processing and purification. Results High level production of HBsAg was carried out with recombinant Pichia pastoris using the methanol inducible AOX1 expression system. The recombinant vaccine was isolated in form of VLPs after several down-stream steps from detergent-treated cell lysates. Search for the intracellular localization of the antigen using electron microscopic studies in combination with immunogold labeling revealed the presence of HBsAg in an extended endoplasmic reticulum where it was found to assemble into defined multi-layered, lamellar structures. The distance between two layers was determined as ~6 nm indicating that these lamellas represent monolayers of well-ordered HBsAg subunits. We did not find any evidence for the presence of VLPs within the endoplasmic reticulum or other parts of the yeast cell. Conclusions It is concluded that high level production and intrinsic slow HBsAg VLP assembly kinetics are leading to retention and accumulation of the antigen in the endoplasmic reticulum where it assembles at least partly into defined lamellar structures. Further transport of HBsAg to the Golgi apparatus is impaired thus leading to secretory pathway disfunction and the formation of an extended endoplasmic reticulum which bulges into irregular cloud-shaped formations. As VLPs were

In vacuo substrate pretreatments for enhancing nanodiamond formation in electron cyclotron resonance plasma

International Nuclear Information System (INIS)

Teii, Kungen; Kouzuma, Yutaka; Uchino, Kiichiro

2006-01-01

Substrate pretreatment conditions at low pressures have been examined for enhancing nanocrystalline diamond formation on silicon in electron cyclotron resonance (ECR) plasma. Three kinds of pretreatments (I) exposure to an ECR H 2 plasma with application of a substrate bias from -100 to +30 V (II) hot-filament heating in H 2 gas, and (III) hot-filament heating in vacuum, were used alone or followed by carburization prior to a two-step process of ion-enhanced nucleation in an ECR plasma and subsequent growth in a hot-filament system. The number density of diamond particles after the final growth step was greatly increased up to the order of 10 7 -10 8 cm -2 when applying pretreatment (I) at the bias of 0 V corresponding to the ion-bombardment energy of around 10 eV. In this treatment, a clean and smooth surface with minimal damage was made by the dominance of anisotropic etching by hydrogen ions over isotropic etching by hydrogen atoms. The number density of diamond particles was still more increased when applying pretreatment (II), but the treated surface was unfavorably contaminated and roughened

Dynamics of Preferential Substrate Recognition in HIV-1 Protease: Redefining the Substrate Envelope

Science.gov (United States)

Özen, Ayşegül; Haliloğlu, Türkan; Schiffer, Celia A.

2011-01-01

HIV-1 protease (PR) permits viral maturation by processing the Gag and Gag-Pro-Pol polyproteins. Though HIV-1 PR inhibitors (PIs) are used in combination antiviral therapy, the emergence of drug resistance has limited their efficacy. The rapid evolution of HIV-1 necessitates the consideration of drug resistance in novel drug-design strategies. Drug-resistant HIV-1 PR variants, while no longer efficiently inhibited, continue to efficiently hydrolyze the natural viral substrates. Though highly diverse in sequence, the HIV-1 PR substrates bind in a conserved three-dimensional shape we defined as the “substrate envelope”. We previously showed that resistance mutations arise where PIs protrude beyond the substrate envelope, as these regions are crucial for drug binding but not for substrate recognition. Here, we extend this model by considering the role of protein dynamics in the interaction of HIV-1 PR with its substrates. Seven molecular dynamics simulations of PR-substrate complexes were performed to estimate the conformational flexibility of substrates in their complexes. Interdependency of the substrate-protease interactions may compensate for the variations in cleavage-site sequences, and explain how a diverse set of sequences can be recognized as substrates by the same enzyme. This diversity may be essential for regulating sequential processing of substrates. We also define a dynamic substrate envelope as a more accurate representation of PR-substrate interactions. This dynamic substrate envelope, described by a probability distribution function, is a powerful tool for drug design efforts targeting ensembles of resistant HIV-1 PR variants with the aim of developing drugs that are less susceptible to resistance. PMID:21762811

Investigation of transient dynamics of capillary assisted particle assembly yield

DEFF Research Database (Denmark)

Tamulevičius, S.; Virganavičius, D.; Juodėnas, M.

2017-01-01

diameter polystyrene beads was performed on patterned poly (dimethyl siloxane) substrates using a custom-built deposition setup. Two types of patterns with different trapping site densities were used to assess CAPA process dynamics and the influence of pattern density and geometry on the deposition yield....... The fluorescence micrographs were analyzed using a custom algorithm enabling to identify particles and calculate efficiency of the deposition performed at different regimes. Relationship between the spatial distribution of particles in transition zone and ambient conditions was evaluated and quantified...... by approximation of the yield profile with a logistic function....

Numerical investigation of radiative properties and surface plasmon resonance of silver nanorod dimers on a substrate

International Nuclear Information System (INIS)

An, Wei; Zhu, Tong; Zhu, QunZhi

2014-01-01

When the distance between two silver nanoparticles is small enough, interparticle surface plasmon coupling has a great impact on their radiative properties. It is becoming a promising technique to use in the sensing and imaging. A model based on finite difference time domain method is developed to investigate the effect of the assembled parameters on the radiative properties and the field-enhancement effect of silver nanorod dimer. The numerical results indicate that the radiative properties of silver nanorod dimer are very sensitive to the assembled angle and the polarization orientation of incident wave. There is great difference on the intensity and location of field-enhancement effect for the cases of different assembled angle and polarization. The most intensive field-enhancement effect occurs in the middle of two nanorods when two nanorods is assembled head to head and the polarization orientation parallels to the length axis of nanorods. Moreover, compared with the single nanorod, the wavelength of extinction peak of dimer has a red-shift, and the intensity of field-enhancement effect on the dimer is more intensive than that of single particle. With the increasing of particle length, extinction cross-section of silver nanorod dimer rises, while extinction efficiency and scattering efficiency firstly increase then drop down gradually. In addition, the extinction peaks of silver nanorod dimer on the substrate are smaller than that without the substrate, and their extinction peaks has a red-shift compared with that without the substrate. -- Highlights: ► Radiative properties of silver nanorod dimer are very sensitive to the assembled angle. ► The projective length of nanorod dimer on the polarization orientation is crucial. ► Compared with single nanorod, wavelength of extinction peak of dimer has a red-shift. ► Extinction peaks of dimer on the substrate are smaller than that without the substrate

Ion exchange substrates for plant cultivation in extraterrestrial stations and space crafts

Science.gov (United States)

Soldatov, Vladimir

2012-07-01

after exhausting. They can serve without additional fertilizers for several years. Their service in the course of exploitation includes only watering. By appearance granular Biona substrate are solid particles with size 0.5-2 mm. Special varieties of Biona substrates, designed for the spacecrafts to withstand zero-gravity conditions, have been made in form of continuous textile materials

Investigation into the role of sodium chloride deposited on oxide and metal substrates in the initiation of hot corrosion

Science.gov (United States)

Birks, N.

1983-01-01

Sodium chloride is deposited on the surface of alumina substrates and exposed to air containing 1% SO2 at temperatures between 500 C and 700 C. In all cases the sodium chloride was converted to sodium sulfate. The volatilization of sodium chloride from the original salt particles was responsible for the development of a uniform coating of sodium sulfate on the alumina substrate. At temperatures above 625 C, a liquid NaCl-Na2SO4 autectic was formed on the substrate. The mechanisms for these reactions are given. One of the main roles of NaCl in low temperature hot corrosion lies in enabling a corrosive liquid to form.

Dynamics of cell area and force during spreading.

Science.gov (United States)

Brill-Karniely, Yifat; Nisenholz, Noam; Rajendran, Kavitha; Dang, Quynh; Krishnan, Ramaswamy; Zemel, Assaf

2014-12-16

Experiments on human pulmonary artery endothelial cells are presented to show that cell area and the force exerted on a substrate increase simultaneously, but with different rates during spreading; rapid-force increase systematically occurred several minutes past initial spreading. We examine this theoretically and present three complementary mechanisms that may accompany the development of lamellar stress during spreading and underlie the observed behavior. These include: 1), the dynamics of cytoskeleton assembly at the cell basis; 2), the strengthening of acto-myosin forces in response to the generated lamellar stresses; and 3), the passive strain-stiffening of the cytoskeleton. Copyright © 2014 Biophysical Society. Published by Elsevier Inc. All rights reserved.

Isolation of technogenic magnetic particles