Proton Induced Structuring of a Photostructurable Glass

2002 ◽  
Vol 739 ◽  
Author(s):  
Meg Abraham ◽  
Inmaculada Gomez-Morilla ◽  
Mike Marsh ◽  
Geoff Grime
Keyword(s):  
Three Dimensional ◽  
Particle Beam ◽  
Nucleation Site ◽  
Buried Structures ◽  
Corning Glass ◽  
Nucleation Sites ◽  
Initial Nucleation ◽  
Similar Product ◽  
Photon Process ◽  
Meta Silicate

ABSTRACTThe use of photons to create intricate three-dimensional and buried structures [1] in photo-structurable glass has been well demonstrated at several institutions [2]. In these instances the glass used whether it be Foturan™, made by the Schott Group or a similar product made by Corning Glass, forms a silver nucleation sites on exposure to intense UV laser light via a two-photon process. Subsequent annealing causes a localized crystal growth to form a meta-silicate phase which can be etched in dilute hydrofluoric acid at rates of 20 to 50 times that of the unprocessed glass. The same formulation of glass can be “exposed” using a particle beam to create the nucleation site. In the case of particle beam exposure, experiments have shown that the mechanisms that cause this initial nucleation and eventual stochiometric transformation, after annealing, depend largely on the beam energy.

New Processing Techniques for the Creation of Micro-Opto-Mechanical Machines and Photonic Devices Embedded in Glass

2002 ◽  
Vol 739 ◽  
Author(s):  
Meg Abraham ◽  
Peter Fuqua ◽  
David P. Taylor ◽  
William W. Hansen ◽  
Henry Helvajian ◽  
...  
Keyword(s):  
Silver Halide ◽  
Three Dimensional ◽  
Direct Write ◽  
Buried Structures ◽  
Nucleation Sites ◽  
New Processing ◽  
Meta Silicate ◽  
Processing Techniques ◽  
Aerospace Corporation ◽  
Nano Wires

ABSTRACTThe use of lasers to create intricate three-dimensional and buried structures [1] in photostructural glass has been well demonstrated at The Aerospace Corporation over the past four years. In these instances the glass used (Foturan™, made by the Schott Group) forms a silver nucleation sites on exposure to intense UV laser light via a two-photon process. Subsequent annealing causes a localized crystal growth to form a meta-silicate phase which can be etched in dilute hydrofluoric acid at rates of 20 to 50 times that of the unprocessed glass. We are now in the process of experimenting with another formulation of photosensitive glass, also pioneered by Corning Glass Works, that behaves differently during the bake process. In the second case, a photoexposure and bake process creates a silver-halide crystal and forms an adjacent void in the glass. A second photoexposure and bake allows for the migration of more silver into the void creating patterned formations of silver nano-wires [2]. Recent experiments with this type of glass have shown that the manipulation of the size and density of the embedded nano-wires as well as the overall pattern of the clusters can be controlled using direct-write exposure to laser processing.

Selective Nucleation and Growth of Large Grain Polycrystalline GaAs

2005 ◽  
Vol 870 ◽  
Author(s):  
C. G. Allen ◽  
J. D. Beach ◽  
A. A. Khandekar ◽  
J. C. Dorr ◽  
C. Veauvy ◽  
...  
Keyword(s):  
Chemical Vapor ◽  
Nucleation Site ◽  
Site Formation ◽  
Organic Chemical ◽  
Subsequent Work ◽  
Nucleation Sites ◽  
Initial Nucleation ◽  
Electrochemically Deposited ◽  
Metal Organic ◽  
Organic Chemical Vapor Deposition

AbstractA method for depositing large grained polycrystalline GaAs on lattice mismatched substrates through controlled nucleation and selective growth is presented. The process was developed on Si wafers. Nucleation site formation began with nanolithography to create submicron holes in photoresist on Si. Ga metal was electrochemically deposited into the holes. Subsequent arsine anneals converted the gallium deposits into GaAs. Photoluminescence and electron diffraction verified conversion to GaAs. Metal-Organic Chemical Vapor Deposition (MOCVD) enlarged the seed crystals to coalescence without creating additional nucleation sites within the patterned field. Having successfully demonstrated the approach, subsequent work has been directed at lower cost, alternative ways to define initial nucleation sites, such as, microcontact lithography and direct decomposition of triethyl gallium to Ga metal in the MOCVD chamber.

Oxygen Precipitation in Silicon: Monte Carlo and Deterministic Studies

1988 ◽  
Vol 141 ◽  
Author(s):  
James P. Lavine ◽  
Russell J. Taras ◽  
Gilbert A. Hawkins
Keyword(s):  
Monte Carlo ◽  
Oxygen Concentration ◽  
Three Dimensional ◽  
Nucleation Site ◽  
Interstitial Oxygen ◽  
Oxygen Precipitation ◽  
Nucleation Sites ◽  
Precipitate Growth ◽  
Oxygen Precipitates ◽  
Oxygen Atoms

AbstractInterstitial oxygen precipitates in silicon during thermal treatment. The amount precipitated increases in an S-shaped fashion as a function of increasing initial interstitial oxygen concentration. A likely hypothesis for this behavior is that the number of nucleation sites that develop into precipitates (successful sites) varies with the initial interstitial oxygen concentration as well as with the precipitation rate at each site. In this paper, a deterministic precipitate growth model is first used to show that a fit to the present data requires the precipitate density to increase by more than a factor of 10 when the oxygen concentration goes from 24 to 40 ppma.Three-dimensional Monte Carlo calculations are then used to show how the nucleation site survival probability depends on the initial number of oxygen atoms at the site and the oxygen concentration. The program treats oxygen diffusion, growth at nucleation sites by the addition of oxygen atoms, and loss at nucleation sites by the escape of oxygen atoms.

Three-Dimensional reconstruction of isolated centrosomes by automated electron tomography

1994 ◽  
Vol 52 ◽  
pp. 310-311
Author(s):  
M.B. Braunfeld ◽  
M. Moritz ◽  
B.M. Alberts ◽  
J.W. Sedat ◽  
D.A. Agard
Keyword(s):  
Electron Tomography ◽  
Three Dimensional ◽  
Vital Role ◽  
Complex Nature ◽  
Animal Cells ◽  
Microtubule Organizing Center ◽  
Nucleation Sites ◽  
Dimensional Reconstruction ◽  
Organizing Center ◽  
Resolution Model

In animal cells, the centrosome functions as the primary microtubule organizing center (MTOC). As such the centrosome plays a vital role in determining a cell's shape, migration, and perhaps most importantly, its division. Despite the obvious importance of this organelle little is known about centrosomal regulation, duplication, or how it nucleates microtubules. Furthermore, no high resolution model for centrosomal structure exists.We have used automated electron tomography, and reconstruction techniques in an attempt to better understand the complex nature of the centrosome. Additionally we hope to identify nucleation sites for microtubule growth.Centrosomes were isolated from early Drosophila embryos. Briefly, after large organelles and debris from homogenized embryos were pelleted, the resulting supernatant was separated on a sucrose velocity gradient. Fractions were collected and assayed for centrosome-mediated microtubule -nucleating activity by incubating with fluorescently-labeled tubulin subunits. The resulting microtubule asters were then spun onto coverslips and viewed by fluorescence microscopy.

Monte Carlo Simulation of Precipitate Nucleation and Growth: Time Dependent Results

1988 ◽  
Vol 141 ◽  
Author(s):  
James P. Lavine ◽  
Gilbert A. Hawkins
Keyword(s):  
Monte Carlo ◽  
Crystalline Silicon ◽  
Three Dimensional ◽  
Nucleation Site ◽  
Nucleation And Growth ◽  
Lattice Points ◽  
Growth Time ◽  
Decay Kinetics ◽  
Time Step ◽  
Oxygen Atoms

AbstractA three-dimensional Monte Carlo computer program has been developed to study the heterogeneous nucleation and growth of oxide precipitates during the thermal treatment of crystalline silicon. In the simulations, oxygen atoms move on a lattice with randomly selected lattice points serving as nucleation sites. The change in free energy that the oxygen cluster would experience in gaining or losing one oxygen atom is used to govern growth or dissolution of the cluster. All the oxygen atoms undergo a jump or a growth decision during each time step of the anneal. The growth and decay kinetics of each nucleation site display interesting fluctuation phenomena. The time dependence of the cluster size generally differs from the expected 3/2 power law due to the fluctuations in oxygen arrival at and incorporation in a precipitate. Competition between growing sites and coarsening are observed.

scholarly journals Initial nucleation site formation due to acoustic droplet vaporization

2014 ◽  
Vol 104 (6) ◽  
pp. 063703 ◽  
Author(s):  
David S. Li ◽  
Oliver D. Kripfgans ◽  
Mario L. Fabiilli ◽  
J. Brian Fowlkes ◽  
Joseph L. Bull
Keyword(s):  
Nucleation Site ◽  
Site Formation ◽  
Acoustic Droplet Vaporization ◽  
Droplet Vaporization ◽  
Initial Nucleation

scholarly journals Restricted nucleation and piRNA-mediated establishment of heterochromatin during embryogenesis in Drosophila miranda

2021 ◽  
Author(s):  
Kevin H.-C. Wei ◽  
Carolus Chan ◽  
Doris Bachtrog
Keyword(s):  
Genome Stability ◽  
Repetitive Sequences ◽  
Developmental Time ◽  
Wide Distribution ◽  
Promoter Regions ◽  
Architectural Feature ◽  
Genome Wide ◽  
Nucleation Sites ◽  
Zygotic Transcription ◽  
Initial Nucleation

Heterochromatin is a key architectural feature of eukaryotic genomes, crucial for silencing of repetitive elements and maintaining genome stability. Heterochromatin shows stereotypical enrichment patterns around centromeres and repetitive sequences, but the molecular details of how heterochromatin is established during embryogenesis are poorly understood. Here, we map the genome-wide distribution of H3K9me3-dependent heterochromatin in individual embryos of D. miranda at precisely staged developmental time points. We find that canonical H3K9me3 enrichment patterns are established early on before cellularization, and mature into stable and broad heterochromatin domains through development. Intriguingly, initial nucleation sites of H3K9me3 enrichment appear as early as embryonic stage3 (nuclear cycle 9) over transposable elements (TE) and progressively broaden, consistent with spreading to neighboring nucleosomes. The earliest nucleation sites are limited to specific regions of a small number of TE families and often appear over promoter regions, while late nucleation develops broadly across most TEs. Early nucleating TEs are highly targeted by maternal piRNAs and show early zygotic transcription, consistent with a model of co-transcriptional silencing of TEs by small RNAs. Interestingly, truncated TE insertions lacking nucleation sites show significantly reduced enrichment across development, suggesting that the underlying sequences play an important role in recruiting histone methyltransferases for heterochromatin establishment.

Design of an LTCC Structure for a Micro-Ceramic Combustor

2012 ◽  
Vol 2012 (CICMT) ◽  
pp. 000288-000293
Author(s):  
Darko Belavic ◽  
Marko Hrovat ◽  
Gregor Dolanc ◽  
Kostja Makarovic ◽  
Marina Santo Zarnik ◽  
...  
Keyword(s):  
High Pressures ◽  
Three Dimensional ◽  
Ceramic Technology ◽  
Electronic Components ◽  
Buried Structures ◽  
Flow Rates ◽  
Points Of View ◽  
Micro Systems ◽  
Micro Combustor ◽  
Harsh Conditions

Advanced micro- or macro-systems are in some cases made with multilayer ceramic technology. Low-Temperature Co-fired Ceramic (LTCC) technology is considered as one of the more suitable technologies for the fabrication of ceramic micro-systems that integrate screen-printed, thick-film electronic components as well as three-dimensional buried structures, for example, cavities and channels. One of the applications is a ceramic combustor. The chemical energy of the fuel is converted into thermal energy in a chemical micro-combustor through a burning process, while the accompanying high temperatures and, frequently, high pressures impose harsh conditions on the combustor structure. Therefore, the combustor must be carefully designed not only from the functional, thermal and chemical points of view, but also with respect to the mechanical strength. The combustor device was prepared by laminating of Du Pont 951PX LTCC green tapes. The fabricated 3D LTCC structures with buried cavities and channels including two inlets (for fuel and air), the evaporator for the fuel, the mixing system of the channels (for mixing the evaporated fuel and air), the distribution channels and eight microburners were realized. The main parts are eight micro-burners realized as buried cavities. In the burners a platinum-based catalyst was deposited to assist the oxidation, i.e., the burning, of the methanol with the air. Thickfilm, platinum-based heaters and temperature sensors are incorporated within the structure. The device was tested with different flow rates of liquid methanol (1 ml/h to 5 ml/h) and air (7 l/h to 15 l/h). The obtained temperatures were between 250°C and 450°C.

Design and Fabrication of an LTCC Structure for a Microceramic Combustor

2012 ◽  
Vol 9 (3) ◽  
pp. 120-125 ◽  
Author(s):  
Darko Belavic ◽  
Marko Hrovat ◽  
Gregor Dolanc ◽  
Kostja Makarovic ◽  
Marina Santo Zarnik
Keyword(s):  
Thick Film ◽  
High Pressures ◽  
Three Dimensional ◽  
Temperature Sensors ◽  
Ceramic Technology ◽  
Electronic Components ◽  
Buried Structures ◽  
Flow Rates ◽  
Points Of View ◽  
Harsh Conditions

Advanced microsystems or macrosystems are in some cases made with multilayer ceramic technology. Low-temperature cofired ceramic (LTCC) technology is considered to be one of the more suitable technologies for the fabrication of ceramic microsystems that integrate screen-printed, thick-film electronic components as well as three-dimensional buried structures, for example, cavities and channels. One of the applications is a ceramic combustor. The chemical energy of the fuel is converted into thermal energy in a chemical microcombustor through a burning process, while the accompanying high temperatures and, frequently, high pressures, impose harsh conditions on the combustor structure. Therefore, the combustor must be carefully designed not only from the functional, thermal, and chemical points of view, but also with respect to the mechanical strength. The combustor device was prepared by lamination of Du Pont 951PX LTCC green tapes. The fabricated 3D LTCC structures with buried cavities and channels including two inlets (for fuel and air), the evaporator for the fuel, the mixing system of the channels (for mixing the evaporated fuel and air), the distribution channels and eight microburners were realized. The main parts are eight microburners realized as buried cavities. In the burners, a platinum-based catalyst was deposited to assist the oxidation, that is, the burning, of the methanol with the air. Thick-film, platinum-based heaters and temperature sensors are incorporated within the structure. The device was tested with different flow rates of liquid methanol (1 mL/h to 5 mL/h) and air (7 L/h to 15 L/h). The temperatures obtained were between 250°C and 450°C.

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