Three Trailblazing Technologies for Schools.

ERIC Educational Resources Information Center

McGinty, Tony

1987-01-01

Provides an overview of the capabilities and potential educational applications of CD-ROM (compact disk read-only memory), artificial intelligence, and speech technology. Highlights include reference materials on CD-ROM; current developments in CD-I (compact disk interactive); synthesized and digital speech for microcomputers, including specific…

Characterization of irradiated AISI 316L stainless steel disks removed from the Spallation Neutron Source

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

Vevera, Bradley J; Hyres, James W; McClintock, David A

2014-01-01

Irradiated AISI 316L stainless steel disks were removed from the Spallation Neutron Source (SNS) for post-irradiation examination (PIE) to assess mechanical property changes due to radiation damage and erosion of the target vessel. Topics reviewed include high-resolution photography of the disk specimens, cleaning to remove mercury (Hg) residue and surface oxides, profile mapping of cavitation pits using high frequency ultrasonic testing (UT), high-resolution surface replication, and machining of test specimens using wire electrical discharge machining (EDM), tensile testing, Rockwell Superficial hardness testing, Vickers microhardness testing, scanning electron microscopy (SEM), and energy dispersive spectroscopy (EDS). The effectiveness of the cleaning proceduremore » was evident in the pre- and post-cleaning photography and permitted accurate placement of the test specimens on the disks. Due to the limited amount of material available and the unique geometry of the disks, machine fixturing and test specimen design were critical aspects of this work. Multiple designs were considered and refined during mock-up test runs on unirradiated disks. The techniques used to successfully machine and test the various specimens will be presented along with a summary of important findings from the laboratory examinations.« less

Evaluation of powder metallurgy superalloy disk materials

NASA Technical Reports Server (NTRS)

Evans, D. J.

1975-01-01

A program was conducted to develop nickel-base superalloy disk material using prealloyed powder metallurgy techniques. The program included fabrication of test specimens and subscale turbine disks from four different prealloyed powders (NASA-TRW-VIA, AF2-1DA, Mar-M-432 and MERL 80). Based on evaluation of these specimens and disks, two alloys (AF2-1DA and Mar-M-432) were selected for scale-up evaluation. Using fabricating experience gained in the subscale turbine disk effort, test specimens and full scale turbine disks were formed from the selected alloys. These specimens and disks were then subjected to a rigorous test program to evaluate their physical properties and determine their suitability for use in advanced performance turbine engines. A major objective of the program was to develop processes which would yield alloy properties that would be repeatable in producing jet engine disks from the same powder metallurgy alloys. The feasibility of manufacturing full scale gas turbine engine disks by thermomechanical processing of pre-alloyed metal powders was demonstrated. AF2-1DA was shown to possess tensile and creep-rupture properties in excess of those of Astroloy, one of the highest temperature capability disk alloys now in production. It was determined that metallographic evaluation after post-HIP elevated temperature exposure should be used to verify the effectiveness of consolidation of hot isostatically pressed billets.

75 FR 23227 - Initial Patent Applications

Federal Register 2010, 2011, 2012, 2013, 2014

2010-05-03

... subject line of the message. Fax: 571-273-0112, marked to the attention of Susan K. Fawcett. Mail: Susan K... FURTHER INFORMATION CONTACT: Requests for additional information should be directed to the attention of... Compact Disk-Read Only Memory (CD-ROM) or Compact Disk-Recordables (CD-R) to submit patent applications...

Application of a Novel DCPD Adjustment Method for the J-R Curve Characterization: A study based on ORNL and ASTM Interlaboratory Results

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

Chen, Xiang; Sokolov, Mikhail A; Nanstad, Randy K

Material fracture toughness in the fully ductile region can be described by a J-integral vs. crack growth resistance curve (J-R curve). As a conventional J-R curve measurement method, the elastic unloading compliance (EUC) method becomes impractical for elevated temperature testing due to relaxation of the material and friction induced back-up shape of the J-R curve. One alternative solution of J-R curve testing applies the Direct Current Potential Drop (DCPD) technique for measuring crack extension. However, besides crack growth, potential drop can also be influenced by plastic deformation, crack tip blunting, etc., and uncertainties exist in the current DCPD methodology especiallymore » in differentiating potential drop due to stable crack growth and due to material deformation. Thus, using DCPD for J-R curve determination remains a challenging task. In this study, a new adjustment procedure for applying DCPD to derive the J-R curve has been developed for conventional fracture toughness specimens, including compact tension, three-point bend, and disk-shaped compact specimens. Data analysis has been performed on Oak Ridge National Laboratory (ORNL) and American Society for Testing and Materials (ASTM) interlaboratory results covering different specimen thicknesses, test temperatures, and materials, to evaluate the applicability of the new DCPD adjustment procedure for J-R curve characterization. After applying the newly-developed procedure, direct comparison between the DCPD method and the normalization method on the same specimens indicated close agreement for the overall J-R curves, as well as the provisional values of fracture toughness near the onset of ductile crack extension, Jq, and of tearing modulus.« less

Holographic Compact Disk Read-Only Memories

NASA Technical Reports Server (NTRS)

Liu, Tsuen-Hsi

1996-01-01

Compact disk read-only memories (CD-ROMs) of proposed type store digital data in volume holograms instead of in surface differentially reflective elements. Holographic CD-ROM consist largely of parts similar to those used in conventional CD-ROMs. However, achieves 10 or more times data-storage capacity and throughput by use of wavelength-multiplexing/volume-hologram scheme.

A DWARF TRANSITIONAL PROTOPLANETARY DISK AROUND XZ TAU B

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

Osorio, Mayra; Macías, Enrique; Anglada, Guillem

We report the discovery of a dwarf protoplanetary disk around the star XZ Tau B that shows all the features of a classical transitional disk but on a much smaller scale. The disk has been imaged with the Atacama Large Millimeter/submillimeter Array (ALMA), revealing that its dust emission has a quite small radius of ∼3.4 au and presents a central cavity of ∼1.3 au in radius that we attribute to clearing by a compact system of orbiting (proto)planets. Given the very small radii involved, evolution is expected to be much faster in this disk (observable changes in a few months)more » than in classical disks (observable changes requiring decades) and easy to monitor with observations in the near future. From our modeling we estimate that the mass of the disk is large enough to form a compact planetary system.« less

The magnetic nature of disk accretion onto black holes.

PubMed

Miller, Jon M; Raymond, John; Fabian, Andy; Steeghs, Danny; Homan, Jeroen; Reynolds, Chris; van der Klis, Michiel; Wijnands, Rudy

2006-06-22

Although disk accretion onto compact objects-white dwarfs, neutron stars and black holes-is central to much of high-energy astrophysics, the mechanisms that enable this process have remained observationally difficult to determine. Accretion disks must transfer angular momentum in order for matter to travel radially inward onto the compact object. Internal viscosity from magnetic processes and disk winds can both in principle transfer angular momentum, but hitherto we lacked evidence that either occurs. Here we report that an X-ray-absorbing wind discovered in an observation of the stellar-mass black hole binary GRO J1655 - 40 (ref. 6) must be powered by a magnetic process that can also drive accretion through the disk. Detailed spectral analysis and modelling of the wind shows that it can only be powered by pressure generated by magnetic viscosity internal to the disk or magnetocentrifugal forces. This result demonstrates that disk accretion onto black holes is a fundamentally magnetic process.

Handbook for Local Coordinators: Value-Added, Compact Disk, Union Catalog Test Phase.

ERIC Educational Resources Information Center

Townley, Charles

In 1988, the Associated College Libraries of Central Pennsylvania received a grant to create a value-added, compact disk, union catalog from the U.S. Department of Education's College Library Technology and Cooperative Grants Program, Title II of the Higher Education Act. Designed to contain, in time, 2,000,830 records from 17 member library…

The Sun's Joules: What is Renewable Energy? An Introduction to "The Sun's Joules" CD-ROM and Energy Education Program.

ERIC Educational Resources Information Center

Weiskopf, Joyce Lowry

This guide accompanies a compact disk that provides a comprehensive collection of information resources. The compact disk is organized according to energy sources and cross-referenced to issues that must be considered when making decisions about energy. This booklet, designed around questions common to high school students, illustrates how the…

An Explanation of the Very Low Radio Flux of Young Planet-mass Companions

NASA Astrophysics Data System (ADS)

Wu, Ya-Lin; Close, Laird M.; Eisner, Josh A.; Sheehan, Patrick D.

2017-12-01

We report Atacama Large Millimeter/submillimeter Array (ALMA) 1.3 mm continuum upper limits for five planetary-mass companions DH Tau B, CT Cha B, GSC 6214-210 B, 1RXS 1609 B, and GQ Lup B. Our survey, together with other ALMA studies, have yielded null results for disks around young planet-mass companions and placed stringent dust mass upper limits, typically less than 0.1 M ⊕, when assuming dust continuum is optically thin. Such low-mass gas/dust content can lead to a disk lifetime estimate (from accretion rates) much shorter than the age of the system. To alleviate this timescale discrepancy, we suggest that disks around wide companions might be very compact and optically thick in order to sustain a few Myr of accretion, yet have very weak (sub)millimeter flux so as to still be elusive to ALMA. Our order-of-magnitude estimate shows that compact optically thick disks might be smaller than 1000 R Jup and only emit ∼μJy of flux in the (sub)millimeter, but their average temperature can be higher than that of circumstellar disks. The high disk temperature could impede satellite formation, but it also suggests that mid- to far-infrared might be more favorable than radio wavelengths to characterize disk properties. Finally, the compact disk size might imply that dynamical encounters between the companion and the star, or any other scatterers in the system, play a role in the formation of planetary-mass companions.

Optical Disks.

ERIC Educational Resources Information Center

Gale, John C.; And Others

1985-01-01

This four-article section focuses on information storage capacity of the optical disk covering the information workstation (uses microcomputer, optical disk, compact disc to provide reference information, information content, work product support); use of laser videodisc technology for dissemination of agricultural information; encoding databases…

40 CFR 63.11995 - In what form and how long must I keep my records?

Code of Federal Regulations, 2013 CFR

2013-07-01

... years. Records may be maintained in hard copy or computer-readable format including, but not limited to, on paper, microfilm, hard disk drive, floppy disk, compact disk, magnetic tape or microfiche. ...

40 CFR 63.11995 - In what form and how long must I keep my records?

Code of Federal Regulations, 2014 CFR

2014-07-01

... years. Records may be maintained in hard copy or computer-readable format including, but not limited to, on paper, microfilm, hard disk drive, floppy disk, compact disk, magnetic tape or microfiche. ...

40 CFR 63.11995 - In what form and how long must I keep my records?

Code of Federal Regulations, 2012 CFR

2012-07-01

... years. Records may be maintained in hard copy or computer-readable format including, but not limited to, on paper, microfilm, hard disk drive, floppy disk, compact disk, magnetic tape or microfiche. ...

40 CFR 63.9060 - In what form and how long must I keep my records?

Code of Federal Regulations, 2010 CFR

2010-07-01

... may be maintained in hard copy or computer-readable format including, but not limited to, on paper, microfilm, hard disk drive, floppy disk, compact disk, magnetic tape, or microfiche. (d) You must keep each...

AFTOMS Technology Issues and Alternatives Report

DTIC Science & Technology

1989-12-01

color , resolu- power requirements, physi- tion; memory , processor speed; cal and weather rugged- IAN interfaces, etc,) f,: these ness. display...Telephone and Telegraph 3 CD-I Compact Disk - Interactive CD-ROM Compact Disk-Read Only Memory CGM Computer Graphics Metafile CNWDI Critical Nuclear...Database Management System RFP Request For Proposal 3 RFS Remote File System ROM Read Only Memory 3 S SA-ALC San Antonio Air Logistics Center 3 SAC

Central Stellar Mass Deficits in the Bulges of Local Lenticular Galaxies, and the Connection with Compact z ~ 1.5 Galaxies

NASA Astrophysics Data System (ADS)

Dullo, Bililign T.; Graham, Alister W.

2013-05-01

We have used the full radial extent of images from the Hubble Space Telescope's Advanced Camera for Surveys and Wide Field Planetary Camera 2 to extract surface brightness profiles from a sample of six, local lenticular galaxy candidates. We have modeled these profiles using a core-Sérsic bulge plus an exponential disk model. Our fast rotating lenticular disk galaxies with bulge magnitudes MV <~ -21.30 mag have central stellar deficits, suggesting that these bulges may have formed from "dry" merger events involving supermassive black holes (BHs) while their surrounding disk was subsequently built up, perhaps via cold gas accretion scenarios. The central stellar mass deficits M def are roughly 0.5-2 M BH (BH mass), rather than ~10-20 M BH as claimed from some past studies, which is in accord with core-Sérsic model mass deficit measurements in elliptical galaxies. Furthermore, these bulges have Sérsic indices n ~3, half-light radii Re < 2 kpc and masses >1011 M ⊙, and therefore appear to be descendants of the compact galaxies reported at z ~ 1.5-2. Past studies which have searched for these local counterparts by using single-component galaxy models to provide the z ~ 0 size comparisons have overlooked these dense, compact, and massive bulges in today's early-type disk galaxies. This evolutionary scenario not only accounts for what are today generally old bulges—which must be present in z ~ 1.5 images—residing in what are generally young disks, but it eliminates the uncomfortable suggestion of a factor of three to five growth in size for the compact, z ~ 1.5 galaxies that are known to possess infant disks.

Fatigue Failure Modes of the Grain Size Transition Zone in a Dual Microstructure Disk

NASA Technical Reports Server (NTRS)

Gabb, Timothy P.; Kantzos, Pete T.; Palsa, Bonnie; Telesman, Jack; Gayda, John; Sudbrack, Chantal K.

2012-01-01

Mechanical property requirements vary with location in nickel-based superalloy disks. In order to maximize the associated mechanical properties, heat treatment methods have been developed for producing tailored grain microstructures. In this study, fatigue failure modes of a grain size transition zone in a dual microstructure disk were evaluated. A specialized heat treatment method was applied to produce varying grain microstructure in the bore to rim portions of a powder metallurgy processed nickel-based superalloy disk. The transition in grain size was concentrated in a zone of the disk web, between the bore and rim. Specimens were extracted parallel and transversely across this transition zone, and multiple fatigue tests were performed at 427 C and 704 C. Grain size distributions were characterized in the specimens, and related to operative failure initiation modes. Mean fatigue life decreased with increasing maximum grain size, going out through the transition zone. The scatter in limited tests of replicates was comparable for failures of uniform gage specimens in all transition zone locations examined.

Forming Disk Galaxies Early in the Universe

NASA Astrophysics Data System (ADS)

Kohler, Susanna

2015-08-01

What were galaxies like in the first 500 million years of the universe? According to simulations by Yu Feng (UC Berkeley) and collaborators, the earliest massive galaxies to form were mostly disk-shaped, rather than the compact clumps previously predicted. Early-Galaxy Models. Current models for galaxy formation predict that small perturbations in the distribution of matter in the early universe collapsed to form very compact, irregular, clumpy first galaxies. Observations support this: the furthest out that we've spotted disk-shaped galaxies is at z=3, whereas the galaxies we've observed from earlier times -- up to redshifts of z=8-10 -- are very compact. But could this be a selection effect, arising from the rarity of large galaxies in the early universe? Current surveys at high redshift have thus far only covered relatively small volumes of space, so it's not necessarily surprising that we haven't yet spotted any large disk galaxies. Similarly, numerical simulations of galaxy formation are limited in the size of the volume they can evolve, so resulting models of early galaxy formation also tend to favor compact clumpy galaxies over large disks. An Enormous Simulation. Pushing at these limitations, Feng and his collaborators used the Blue Waters supercomputer to carry out an enormous cosmological hydrodynamic simulation called BlueTides. In this simulation, they track 700 billion particles as they evolve in a volume of 400 comoving Mpc/h -- 40 times the volume of the largest previous simulation and 300 times the volume of the largest observational survey at these redshifts. What they find is that by z=8, a whopping 70% of the most massive galaxies (over 7 billion solar masses each) were disk-shaped, though they are more compact, gas-rich, and turbulent than present-day disk galaxies like the Milky Way. The way the most massive galaxies formed in the simulation also wasn't expected: rather than resulting from major mergers, they were built from smooth accretion onto the disks from nearby filaments. These simulations suggest we still have a lot to learn about the structure of galaxies in the early universe and how they formed. Luckily, future telescope projects should help us out: Feng and collaborators estimate that the WFIRST satellite, for instance, should have the capability to detect 8000 disk galaxies of the type BlueTides predicts -- compared to the weak 30% chance of finding a single one in the current largest-area Hubble survey!

In vitro effectiveness of antimicrobial photodynamic therapy (APDT) using a 660 nm laser and malachite green dye in Staphylococcus aureus biofilms arranged on compact and cancellous bone specimens.

PubMed

Rosa, Luciano Pereira; da Silva, Francine Cristina; Nader, Sumaia Alves; Meira, Giselle Andrade; Viana, Magda Souza

2014-11-01

The aim of this study was to evaluate the in vitro effectiveness of antimicrobial photodynamic therapy (APDT) using a 660 nm visible laser combined with malachite green (MG) dye in the inactivation of Staphylococcus aureus (ATCC 25923) biofilms formed within compact and cancellous bone specimens. Specimens of 80 compact bones and 80 cancellous bones were contaminated with a standard suspension of S. aureus and incubated for 14 days at 37 °C to allow for the formation of biofilms. The specimens were divided into the following groups (n = 10) according to the treatment conditions: PS-L - (control - no treatment), PS+L - (only MG for 5 min), PS-L + 90 (only laser irradiation for 90 s), PS-L + 180 (only laser irradiation for 180 s), PS-L + 300 (only laser irradiation for 300 s), APDT90 (APDT for 90 s), APDT180 (APDT for 180 s), and APDT300 (APDT for 300 s). The findings were statistically analyzed using an ANOVA 5%. All of the experimental groups were significantly different from the control group for both the compact and cancellous bone specimens. The compact bone specimens that received APDT treatment (for either 90, 180, or 300 s) showed reductions in the log10 CFU/ml of S. aureus by a magnitude of 4 log10. Cancellous bone specimens treated with 300 s of APDT showed the highest efficacy, and these specimens had a reduction in S. aureus CFU/ml by a factor of 3 log10. APDT treatment using these proposed parameters in combination with MG was effective at inactivating S. aureus biofilms in compact and cancellous bone specimens.

Mode 1 stress intensity factors for round compact specimens

NASA Technical Reports Server (NTRS)

Gross, B.

1976-01-01

The mode 1 stress intensity factors were computed for round compact specimens by the boundary collocation method. Results are presented for ratios A sub T/R sub 0 in the range 0.3 to 0.8, where A sub t is the distance from the specimen center to the crack tip for a specimen of diameter 2R sub 0.

Inner Edges of Compact Debris Disks around Metal-rich White Dwarfs

NASA Astrophysics Data System (ADS)

Rafikov, Roman R.; Garmilla, José A.

2012-12-01

A number of metal-rich white dwarfs (WDs) are known to host compact, dense particle disks, which are thought to be responsible for metal pollution of these stars. In many such systems, the inner radii of disks inferred from their spectra are so close to the WD that particles directly exposed to starlight must be heated above 1500 K and are expected to be unstable against sublimation. To reconcile this expectation with observations, we explore particle sublimation in H-poor debris disks around WDs. We show that because of the high metal vapor pressure the characteristic sublimation temperature in these disks is 300-400 K higher than in their protoplanetary analogs, allowing particles to survive at higher temperatures. We then look at the structure of the inner edges of debris disks and show that they should generically feature superheated inner rims directly exposed to starlight with temperatures reaching 2500-3500 K. Particles migrating through the rim toward the WD (and rapidly sublimating) shield the disk behind them from strong stellar heating, making the survival of solids possible close to the WD. Our model agrees well with observations of WD+disk systems provided that disk particles are composed of Si-rich material such as olivine, and have sizes in the range ~0.03-30 cm.

Unmanned Systems Acquisition and Technology Development: Is a More Integrated Approach Required

DTIC Science & Technology

2010-11-01

The initial niche market of college students grew and in a few years, the music industry was forced to completely change its business models as...accepted and initially more effective sustaining technologies.39 An example of a sustaining technology would be the compact disk within the music ... industry . Like the advancement from the vinyl record to the cassette tape, the incremental advance to the compact disk was a vast improvement over the

Fluffy dust forms icy planetesimals by static compression

NASA Astrophysics Data System (ADS)

Kataoka, Akimasa; Tanaka, Hidekazu; Okuzumi, Satoshi; Wada, Koji

2013-09-01

Context. Several barriers have been proposed in planetesimal formation theory: bouncing, fragmentation, and radial drift problems. Understanding the structure evolution of dust aggregates is a key in planetesimal formation. Dust grains become fluffy by coagulation in protoplanetary disks. However, once they are fluffy, they are not sufficiently compressed by collisional compression to form compact planetesimals. Aims: We aim to reveal the pathway of dust structure evolution from dust grains to compact planetesimals. Methods: Using the compressive strength formula, we analytically investigate how fluffy dust aggregates are compressed by static compression due to ram pressure of the disk gas and self-gravity of the aggregates in protoplanetary disks. Results: We reveal the pathway of the porosity evolution from dust grains via fluffy aggregates to form planetesimals, circumventing the barriers in planetesimal formation. The aggregates are compressed by the disk gas to a density of 10-3 g/cm3 in coagulation, which is more compact than is the case with collisional compression. Then, they are compressed more by self-gravity to 10-1 g/cm3 when the radius is 10 km. Although the gas compression decelerates the growth, the aggregates grow rapidly enough to avoid the radial drift barrier when the orbital radius is ≲6 AU in a typical disk. Conclusions: We propose a fluffy dust growth scenario from grains to planetesimals. It enables icy planetesimal formation in a wide range beyond the snowline in protoplanetary disks. This result proposes a concrete initial condition of planetesimals for the later stages of the planet formation.

Detailed Microstructural Characterization of the Disk Alloy ME3

NASA Technical Reports Server (NTRS)

Gabb, Timothy P.; Garg, Anita; Ellis, David L.; O'Connor, Kenneth M.

2004-01-01

The advanced powder metallurgy disk alloy ME3 was designed using statistical screening and optimization of composition and processing variables in the NASA/General Electric/Pratt & Whitney HSR/EPM disk program to have extended durability for large disks at maximum temperatures of 600 to 700 C. Scaled-up disks of this alloy were then produced at the conclusion of that program to demonstrate these properties in realistic disk shapes. The objective of the present study was to assess the microstructural characteristics of these ME3 disks at two consistent locations, in order to enable estimation of the variations in microstructure across each disk and across several disks of this advanced alloy. Scaled-up disks processed in the HSR/EPM Compressor/Turbine Disk program had been sectioned, machined into specimens, and tested in tensile, creep, fatigue, and fatigue crack growth tests by NASA Glenn Research Center, in cooperation with General Electric Engine Company and Pratt & Whitney Aircraft Engines. For this study, microstructures of grip sections from tensile specimens in the bore and rim were evaluated from these disks. The major and minor phases were identified and quantified using transmission electron microscopy (TEM). Particular attention was directed to the .' precipitates, which along with grain size can predominantly control the mechanical properties of superalloy disks.

Wide range stress intensity factor expressions for ASTM E 399 standard fracture toughness specimens

NASA Technical Reports Server (NTRS)

Srawley, J. E.

1976-01-01

For each of the two types of specimens, bend and compact, described previously for plane strain fracture toughness of materials, E 399, a polynominal expression is given for calculation of the stress intensity factor, K, from the applied force, P, and the specimen dimensions. It is explicitly stated, however, that these expressions should not be used outside the range of relative crack length, a/W, from 0.45 to 0.55. While this range is sufficient for the purpose of E 399, the same specimen types are often used for other purposes over a much wider range of a/W; for example, in the study of fatigue crack growth. Expressions are presented which are at least as accurate as those in E 399-74, and which cover much wider ranges of a/W: for the three-point bend specimen from 0 to 1; and for the compact specimen from 0.2 to 1. The range has to be restricted for the compact specimen because of the proximity of the loading pin holes to the crackline, which causes the stress intensity factor to be sensitive to small variations in dimensions when a/W is small. This is a penalty inherently associated with the compactness of the specimen.

A Discovery of a Compact High Velocity Cloud-Galactic Supershell System

NASA Astrophysics Data System (ADS)

Park, Geumsook; Koo, Bon-Chul; Kang, Ji-hyun; Gibson, Steven J.; Peek, Joshua Eli Goldston; Douglas, Kevin A.; Korpela, Eric J.; Heiles, Carl E.

2017-01-01

High velocity clouds (HVCs) are neutral hydrogen (HI) gas clouds having very different radial velocities from those of the Galactic disk material. While some large HVC complexes are known to be gas streams tidally stripped from satellite galaxies of the Milky Way, there are relatively isolated and small angular-sized HVCs, so called “compact HVCs (CHVCs)”, the origin of which remains controversial. There are about 300 known CHVCs in the Milky Way, and many of them show a head-tail structure, implying a ram pressure interaction with the diffuse Galactic halo gas. It is, however, not clear whether CHVCs are completely dissipated in the Galactic halo to feed the multi-phase circumgalactic medium or they can survive their trip through the halo and collide with the Galactic disk. The colliding CHVCs may leave a gigantic trail in the disk, and it had been suggested that some of HI supershells that require ≧ 3 x 1052 erg may be produced by the collision of such HVCs.Here we report the detection of a kiloparsec (kpc)-size supershell in the outskirts of the Milky Way with the compact HVC 040+01-282 (hereafter, CHVC040) at its geometrical center using the “Inner-Galaxy Arecibo L-band Feed Array” HI 21 cm survey data. The morphological and physical properties of both objects suggest that CHVC040, which is either a fragment of a nearby disrupted galaxy or a cloud that originated from an intergalactic accreting flow, collided with the disk ˜5 Myr ago to form the supershell. Our results show that some compact HVCs can survive their trip through the Galactic halo and inject energy and momentum into the Milky Way disk.

Recent Observational Progress on Accretion Disks Around Compact Objects

NASA Astrophysics Data System (ADS)

Miller, Jon M.

2016-04-01

Studies of accretion disks around black holes and neutron stars over the last ten years have made remarkable progress. Our understanding of disk evolution as a function of mass accretion rate is pushing toward a consensus on thin/thick disk transitions; an apparent switching between disk-driven outflow modes has emerged; and monitoring observations have revealed complex spectral energy distributions wherein disk reprocessing must be important. Detailed studies of disk winds, in particular, have the potential to reveal the basic physical processes that mediate disk accretion, and to connect with numerical simulations. This talk will review these developments and look ahead to the potential of Astro-H.

A 100 au Wide Bipolar Rotating Shell Emanating from the HH 212 Protostellar Disk: A Disk Wind?

NASA Astrophysics Data System (ADS)

Lee, Chin-Fei; Li, Zhi-Yun; Codella, Claudio; Ho, Paul T. P.; Podio, Linda; Hirano, Naomi; Shang, Hsien; Turner, Neal J.; Zhang, Qizhou

2018-03-01

HH 212 is a Class 0 protostellar system found to host a “hamburger”-shaped dusty disk with a rotating disk atmosphere and a collimated SiO jet at a distance of ∼400 pc. Recently, a compact rotating outflow has been detected in SO and SO2 toward the center along the jet axis at ∼52 au (0.″13) resolution. Here we resolve the compact outflow into a small-scale wide-opening rotating outflow shell and a collimated jet, with the observations in the same S-bearing molecules at ∼16 au (0.″04) resolution. The collimated jet is aligned with the SiO jet, tracing the shock interactions in the jet. The wide-opening outflow shell is seen extending out from the inner disk around the SiO jet and has a width of ∼100 au. It is not only expanding away from the center, but also rotating around the jet axis. The specific angular momentum of the outflow shell is ∼40 au km s‑1. Simple modeling of the observed kinematics suggests that the rotating outflow shell can trace either a disk wind or disk material pushed away by an unseen wind from the inner disk or protostar. We also resolve the disk atmosphere in the same S-bearing molecules, confirming the Keplerian rotation there.

Libraries and Desktop Storage Options: Results of a Web-Based Survey.

ERIC Educational Resources Information Center

Hendricks, Arthur; Wang, Jian

2002-01-01

Reports the results of a Web-based survey that investigated what plans, if any, librarians have for dealing with the expected obsolescence of the floppy disk and still retain effective library service. Highlights include data storage options, including compact disks, zip disks, and networked storage products; and a copy of the Web survey.…

Antimicrobial photodynamic inactivation of Staphylococcus aureus biofilms in bone specimens using methylene blue, toluidine blue ortho and malachite green: An in vitro study.

PubMed

Rosa, Luciano Pereira; da Silva, Francine Cristina; Nader, Sumaia Alves; Meira, Giselle Andrade; Viana, Magda Souza

2015-05-01

To evaluate the in vitro effectiveness of APDI with a 660 nm laser combined with methylene blue (MB), toluidine blue ortho (TBO) and malachite green (MG) dyes to inactivate Staphylococcus aureus (ATCC 25923) biofilms in compact and cancellous bone specimens. Eighty specimens of compact and 80 of cancellous bone were contaminated with a standard suspension of the microorganism and incubated for 14 days at 37°C to form biofilms. After this period, the specimens were divided into groups (n=10) according to established treatment: PS-L- (control - no treatment); PSmb+L-, PStbo+L-, PSmg+L- (only MB, TBO or MG for 5 min in the dark); PS-L+ (only laser irradiation for 180 s); and APDImb, APDItbo and APDImg (APDI with MB, TBO or MG for 180 s). The findings were statistically analyzed by ANOVA at 5% significance levels. All experimental treatments showed significant reduction of log CFU/mL S. aureus biofilms when compared with the control group for compact and cancellous bones specimens; the APDI group's treatment was more effective. The APDI carried out for the compact specimens showed better results when compared with cancellous specimens at all times of application. For the group of compact bone, APDImg showed greater reductions in CFU/mL (4.46 log 10). In the group of cancellous bone, the greatest reductions were found in the APDImb group (3.06 log 10). APDI with methylene blue, toluidine blue ortho and malachite green dyes and a 660 nm laser proved to be effective in the inactivation of S. aureus biofilms formed in compact and cancellous bone. Copyright © 2015 Elsevier Ltd. All rights reserved.

Effectiveness of antimicrobial photodynamic therapy using a 660 nm laser and methyline blue dye for inactivating Staphylococcus aureus biofilms in compact and cancellous bones: An in vitro study.

PubMed

Rosa, Luciano Pereira; Silva, Francine Cristina da; Nader, Sumaia Alves; Meira, Giselle Andrade; Viana, Magda Souza

2015-06-01

New therapeutic modalities such as antimicrobial photodynamic therapy (APDT) has been investigated in order to be a valid alternative to the treatment of infections caused by different microorganisms. This work evaluated the in vitro effectiveness of Antimicrobial Photodynamic Therapy (APDT) using 660 nm laser combined with methylene blue dye to inactivate Staphylococcus aureus (ATCC 25923) biofilms in compact and cancellous bones specimens. Eighty specimens of compact bone and 80 specimens of cancellous bone were contaminated with a standard suspension of S. aureus and incubated for 14 days at 37°C to induce the formation of biofilms. The specimens were then divided into groups (n = 10) according to the established treatment: PS-L- (control--no treatment), PS+L- (only AM for 5 min in the dark), PS-L+90 (only laser irradiation for 90 s), PS-L+180 (only laser irradiation for 180 s), PS-L+300 (only laser irradiation for 300 s), APDT90 (APDT for 90 s), APDT180 (APDT for 180 s), and APDT300 (APDT for 300 s). The findings were statistically analyzed by ANOVA 5%. All of the experimental treatments showed a significant reduction (log 10 CFU/mL) of S. aureus biofilms in compact and cancellous bones specimens compared with the control group, and the APDT group was the most effective. Compact specimens treated with APDT showed the greatest reduction in biofilms compared with cancellous specimens, regardless of length of treatment. APDT with methylene blue dye and a 660 nm laser proved to be effective in inactivating S. aureus biofilms formed in compact and cancellous bone. Copyright © 2015 Elsevier B.V. All rights reserved.

Collection of Human Wastes on Long Missions

NASA Technical Reports Server (NTRS)

Jennings, D. C.; Lewis, T. A.; Brose, H. F.

1986-01-01

Report evaluates and compares three alternative approaches to hygienic containment of human wastes. Three practical means of waste collection: filter-bag collection with compaction by fan suction, canister collection with compaction by force applied to compaction cups or disks, and sleeve collection with compaction by rollers and winding on reel. Potentially useful in airplanes, buses, boats, trains, and campers and temporary toilets for construction sites and outdoor gatherings.

Disk Residual Life Studies. Part 1. F100 1st-Stage Turbine Disk (IN100)

DTIC Science & Technology

1979-12-01

mag- nifying lens Static FPI was augmented by wink FPI while phase II specimens were installed in the fatigue test machine. This form of inspection...Failure at thermocouple tack weld. Fractography : no cracks in bolthole BR-3 Test Temperatu,-e, = 10000F, o,,, 90 kIoBR- Pretest - No No No Hole honed and... Fractography no cracks in bolthole 44! ! ’ Ai N3Wp IOLTHOLE SPECIMEN Vt 4; TABLESS FATIGUE TEST INSPEC’rIoN RECORDS (Confiilued) Specimen ks.oecoon

Fracture toughness testing of Linde 1092 reactor vessel welds in the transition range using Charpy-sized specimens

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

Pavinich, W.A.; Yoon, K.K.; Hour, K.Y.

1999-10-01

The present reference toughness method for predicting the change in fracture toughness can provide over estimates of these values because of uncertainties in initial RT{sub NDT} and shift correlations. It would be preferable to directly measure fracture toughness. However, until recently, no standard method was available to characterize fracture toughness in the transition range. ASTM E08 has developed a draft standard that shows promise for providing lower bound transition range fracture toughness using the master curve approach. This method has been successfully implemented using 1T compact fracture specimens. Combustion Engineering reactor vessel surveillance programs do not have compact fracture specimens.more » Therefore, the CE Owners Group developed a program to validate the master curve method for Charpy-sized and reconstituted Charpy-sized specimens for future application on irradiated specimens. This method was validated for Linde 1092 welds using unirradiated Charpy-sized and reconstituted Charpy-sized specimens by comparison of results with those from compact fracture specimens.« less

[Study on physical properties of titanium alloy sample fabricated with vacuum-sintered powder metallurgy].

PubMed

Ding, X; Liang, X; Chao, Y; Han, X

2000-06-01

To investigate the physical properties of titanium alloy fabricated with vacuum-sintered powder metallurgy. The titanium powders of three different particle sizes(-160mesh, -200 - +300mesh, -300mesh) were selected, and mixed with copper and aluminum powder in different proportions. Two other groups were made up of titanium powder(-200 - +300mesh) plated with copper and tin. The build-up and, condensation method and a double-direction press with a metal mold were used. The green compacts were sintered at 1000 degrees C for 15 minutes in a vacuum furnace at 0.025 Pa. In the double-direction press, the specimens were compacted at the pressure of 100 MPa, 200 MPa and 300 MPa respectively. Then the linear shrinkage ratio and the opening porosity of the sintered compacts were evaluated respectively. 1. The linear shrinkage ratio of specimens decreased with the increased compacted pressure(P < 0.05). There was no significant difference among the linear shrinkage ratios of three different titanium powders at the same compacted pressure(P > 0.05), but that of titanium powder plated with copper and tin was higher than those of other specimens without plating(P < 0.05). 2. The opening porosity of specimens decreased with the increased compacted pressure(P < 0.05). Three different sized particle of titanium powder did not affect the opening porosity at the same compacted pressure(P > 0.05). The composition of titanium-based metal powder mixtures and the compacted pressures affect the physical properties of sintered compacts. Titanium powder plated with copper and tin is compacted and sintered easily, and the physical properties of sintered compacts are greatly improved.

Determination of proper mixing and compacting temperatures of laboratory fabricated asphalt concrete specimens.

DOT National Transportation Integrated Search

1995-04-01

The Oregon Department of Transportation (ODOT) Materials Unit has historically used one temperature for the mixing and compacting of laboratory fabricated asphalt concrete specimens. Since switching to the performance based asphalt (PBA) specificatio...

Enhancing the Scientific Return from HST Imaging of Debris Disks

NASA Astrophysics Data System (ADS)

Weinberger, Alycia

2016-10-01

We propose realistic modeling of scattering of light by small aggregate dust grains that will enable us to interpret visible to near-infrared imaging of debris disks. We will determine if disk colors, phase functions, and polarizations place unique constraints on the composition of debris dust. Ongoing collisions of planetesimals generate dust; therefore, the dust provides unique information on compositions of the parent bodies. These exosolar analogs of asteroids and comets can bear clues to the history of a planetary system including migration and thermal processing. Because directly imaged debris disks are cold, they have no solid state emission features. Grain scattering properties as a function of wavelength are our only tool to reveal their compositions. Solar system interplanetary dust particles are fluffy aggregates, but most previous work on debris disk composition relied on Mie theory, i.e. assumed compact spherical grains. Mie calculations do not reproduce the observed colors and phase functions observed from debris disks. The few more complex calculations that exist do not explore the range of compositions and sizes relevant to debris disk dust. In particular, we expect porosity to help distinguish between cometary-like parent bodies, which are fluffy due to high volatile content and low collisional velocities, and asteroidal-like parent bodies that are compacted.

ALMA detection of a disk wind from HD 163296

NASA Astrophysics Data System (ADS)

Klaassen, Pamela; Juhasz, Attila; Mathews, Geoffrey; Mottram, Joseph; De Gregorio-Monsalvo, Itziar; van Dishoeck, Ewine; Takahashi, Satoko; Akiyama, Eiji; Chapillon, Edwige; Espada, Daniel; Hales, Antonio; Hogerheijde, Michiel; Rawlings, Mark; Schmalzl, Markus; Testi, Leonardo

2013-07-01

Disk winds have been postulated as a mechanism for angular momentum release in protostellar systems for decades. HD 163296 is a Herbig Ae star surrounded by a disk and has been shown to host a series of HH knots (HH 409) with bow shocks associated with the farthest knots. Here we present ALMA Science Verification data of CO J=2-1 and J=3-2 emission which are spatially coincident with the blue shifted jet of HH knots, and offset from the disk by -18.6 km/s. The emission has a double corkscrew morphology and extends more than 10'' from the disk with embedded emission clumps coincident with jet knots. We interpret this double corkscrew as emission from material in a molecular disk wind, and that the compact emission near the jet knots is being heated by the jet which is moving at much higher velocities. We show that the J=3-2 emission is likely heavily filtered by the interferometer, but the J=2-1 emission suffers less due to the larger beam and measurable angular scales. Excitation analysis suggests temperatures exceeding 900 K in these compact features. The high mass loss rate suggests that this star is dispersing the disk faster than it is funneling mass onto the star, signaling the end of the main accretion phase.

Structures and properties of materials recovered from high shock pressures

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

Nellis, W.J.

1994-03-01

Shock compression produces high dynamic pressures, densities, temperatures, and their quench rates. Because of these extreme conditions, shock compression produces materials with novel crystal structures, microstructures, and physical properties. Using a 6.5-m-long two-stage gun, we perform experiments with specimens up to 10 mm in diameter and 0.001--1 mm thick. For example, oriented disks of melt-textured superconducting YBa{sub 2}Cu{sub 3}O{sub 7} were shocked to 7 GPa without macroscopic fracture. Lattice defects are deposited in the crystal, which improve magnetic hysteresis at {approximately}1 kOe. A computer code has been developed to simulate shock compaction of 100 powder particles. Computations will be comparedmore » with experiments with 15--20 {mu}m Cu powders. The method is applicable to other powders and dynamic conditions.« less

Manifestations of dynamo driven large-scale magnetic field in accretion disks of compact objects

NASA Technical Reports Server (NTRS)

Chagelishvili, G. D.; Chanishvili, R. G.; Lominadze, J. G.; Sokhadze, Z. A.

1991-01-01

A turbulent dynamo nonlinear theory of turbulence was developed that shows that in the compact objects of accretion disks, the generated large-scale magnetic field (when the generation takes place) has a practically toroidal configuration. Its energy density can be much higher than turbulent pulsations energy density, and it becomes comparable with the thermal energy density of the medium. On this basis, the manifestations to which the large-scale magnetic field can lead at the accretion onto black holes and gravimagnetic rotators, respectively, are presented.

A hot compact dust disk around a massive young stellar object.

PubMed

Kraus, Stefan; Hofmann, Karl-Heinz; Menten, Karl M; Schertl, Dieter; Weigelt, Gerd; Wyrowski, Friedrich; Meilland, Anthony; Perraut, Karine; Petrov, Romain; Robbe-Dubois, Sylvie; Schilke, Peter; Testi, Leonardo

2010-07-15

Circumstellar disks are an essential ingredient of the formation of low-mass stars. It is unclear, however, whether the accretion-disk paradigm can also account for the formation of stars more massive than about 10 solar masses, in which strong radiation pressure might halt mass infall. Massive stars may form by stellar merging, although more recent theoretical investigations suggest that the radiative-pressure limit may be overcome by considering more complex, non-spherical infall geometries. Clear observational evidence, such as the detection of compact dusty disks around massive young stellar objects, is needed to identify unambiguously the formation mode of the most massive stars. Here we report near-infrared interferometric observations that spatially resolve the astronomical-unit-scale distribution of hot material around a high-mass ( approximately 20 solar masses) young stellar object. The image shows an elongated structure with a size of approximately 13 x 19 astronomical units, consistent with a disk seen at an inclination angle of approximately 45 degrees . Using geometric and detailed physical models, we found a radial temperature gradient in the disk, with a dust-free region less than 9.5 astronomical units from the star, qualitatively and quantitatively similar to the disks observed in low-mass star formation. Perpendicular to the disk plane we observed a molecular outflow and two bow shocks, indicating that a bipolar outflow emanates from the inner regions of the system.

Determining mechanical behavior of solid materials using miniature specimens

DOEpatents

Manahan, Michael P.; Argon, Ali S.; Harling, Otto K.

1986-01-01

A Miniaturized Bend Test (MBT) capable of extracting and determining mechanical behavior information from specimens only so large as to have at least a volume or smallest dimension sufficient to satisfy continuum behavior in all directions. The mechanical behavior of the material is determined from the measurements taken during the bending of the specimen and is processed according to the principles of linear or nonlinear material mechanics or both. In a preferred embodiment the determination is carried out by a code which is constructed according to the finite element method, and the specimen used for the determinations is a miniature disk simply supported for central loading at the axis on the center of the disk.

New generation of compact high power disk lasers

NASA Astrophysics Data System (ADS)

Feuchtenbeiner, Stefanie; Zaske, Sebastian; Schad, Sven-Silvius; Gottwald, Tina; Kuhn, Vincent; Kumkar, Sören; Metzger, Bernd; Killi, Alexander; Haug, Patrick; Speker, Nicolai

2018-02-01

New technological developments in high power disk lasers emitting at 1030 nm are presented. These include the latest generation of TRUMPF's TruDisk product line offering high power disk lasers with up to 6 kW output power and beam qualities of up to 4 mm*mrad. With these compact devices a footprint reduction of 50% compared to the previous model could be achieved while at the same time improving robustness and increasing system efficiency. In the context of Industry 4.0, the new generation of TruDisk lasers features a synchronized data recording of all sensors, offering high-quality data for virtual analyses. The lasers therefore provide optimal hardware requirements for services like Condition Monitoring and Predictive Maintenance. We will also discuss its innovative and space-saving cooling architecture. It allows operation of the laser under very critical ambient conditions. Furthermore, an outlook on extending the new disk laser platform to higher power levels will be given. We will present a disk laser with 8 kW laser power out of a single disk with a beam quality of 5 mm*mrad using a 125 μm fiber, which makes it ideally suited for cutting and welding applications. The flexibility of the disk laser platform also enables the realization of a wide variety of beam guiding setups. As an example a new scheme called BrightLine Weld will be discussed. This technology allows for an almost spatter free laser welding process, even at high feed rates.

Probing circumplanetary disks with MagAO and ALMA

NASA Astrophysics Data System (ADS)

Wu, Ya-Lin

2018-01-01

The dedication of the Magellan Adaptive Optics (MagAO) on the 6.5 m Clay Telescope has opened a new era in high-contrast imaging. Its unique diffraction-limited wavelengths of 0.6 to 1 micron helps to probe circumplanetary disks by measuring the amount of dust reddening as well as by searching for the strongest gas accretion indicator H-alpha (0.65 micron). Using MagAO, I found that two wide-orbit planetary-mass companions CT Cha B and 1RXS 1609 B have a significant dust extinction of Av ~ 3 to 5 mag likely from their disks. For GQ Lup B, I found that it is actively accreting material from its disk and emitting strong H-alpha emission. My research with MagAO demonstrates that circumplanetary disks could be ubiquitous among young giant planets. I later carried out a survey using ALMA to image accretion disks around several wide planet-mass companions at 1.3 mm continuum and CO (2-1). This is the first systematic study aiming to measure the size, mass, and structure of planetary disks. However, except for FW Tau C (which was shown to actually be a low-mass star from the dynamical mass measurement) no disks around the companions were found in my ALMA survey. This surprising null result implies that circumplanetary disks are much more compact and denser than expected, so they are faint and optically thick in the radio wavelengths. Therefore, mid- to far-infrared may be more favorable to characterize disk properties. The MIRI camera on the JWST can test this compact optically-thick disk hypothesis by probing disk thermal emission between 10 and 25 micron.

Shear bond strength between an indirect composite layering material and feldspathic porcelain-coated zirconia ceramics.

PubMed

Fushiki, Ryosuke; Komine, Futoshi; Blatz, Markus B; Koizuka, Mai; Taguchi, Kohei; Matsumura, Hideo

2012-10-01

This study aims to evaluate the effect of both feldspathic porcelain coating of zirconia frameworks and priming agents on shear bond strength between an indirect composite material and zirconia frameworks. A total of 462 airborne-particle-abraded zirconia disks were divided into three groups: untreated disks (ZR-AB), airborne-particle-abraded zirconia disks coated with feldspathic porcelain, (ZR-PO-AB), and hydrofluoric acid-etched zirconia disks coated with feldspathic porcelain (ZR-PO-HF). Indirect composite (Estenia C&B) was bonded to zirconia specimens with no (CON) or one of four priming agents--Clearfil Photo Bond (CPB), Clearfil Photo Bond with Clearfil Porcelain Bond Activator (CPB + activator), Estenia Opaque primer, or Porcelain Liner M Liquid B (PLB)--with or without an opaque material (Estenia C&B Opaque). All specimens were tested for shear bond strength before and after 20,000 thermocycles. The Steel-Dwass test and Mann-Whitney U test were used to compare shear bond strength. In ZR-AB specimens, the initial bond strength of the CPB and CPB + Activator groups was significantly higher as compared with the other three groups (P < 0.05), whereas the PLB and CPB + Activator groups had the highest pre- and post-thermocycling bond strengths in ZR-PO-AB and ZR-PO-HF specimens. Among CON disks without opaque material, bond strength was significantly lower in ZR-AB specimens than in ZR-PO-AB and ZR-PO-HF specimens (P < 0.05). Feldspathic porcelain coating of a Katana zirconia framework enhanced the bond strength of Estenia C&B indirect composite to zirconia independent of surface treatment. The use of a silane coupling agent and opaque material yields durable bond strength between the indirect composite and feldspathic-porcelain-coated zirconia. The results of the present study suggest that feldspathic porcelain coating of zirconia frameworks is an effective method to obtain clinically acceptable bond strengths of a layering indirect composite material to a zirconia framework.

Protoplanetary Disk Properties in the Orion Nebula Cluster: Initial Results from Deep, High-resolution ALMA Observations

NASA Astrophysics Data System (ADS)

Eisner, J. A.; Arce, H. G.; Ballering, N. P.; Bally, J.; Andrews, S. M.; Boyden, R. D.; Di Francesco, J.; Fang, M.; Johnstone, D.; Kim, J. S.; Mann, R. K.; Matthews, B.; Pascucci, I.; Ricci, L.; Sheehan, P. D.; Williams, J. P.

2018-06-01

We present Atacama Large Millimeter Array 850 μm continuum observations of the Orion Nebula Cluster that provide the highest angular resolution (∼0.″1 ≈ 40 au) and deepest sensitivity (∼0.1 mJy) of the region to date. We mosaicked a field containing ∼225 optical or near-IR-identified young stars, ∼60 of which are also optically identified “proplyds.” We detect continuum emission at 850 μm toward ∼80% of the proplyd sample, and ∼50% of the larger sample of previously identified cluster members. Detected objects have fluxes of ∼0.5–80 mJy. We remove submillimeter flux due to free–free emission in some objects, leaving a sample of sources detected in dust emission. Under standard assumptions of isothermal, optically thin disks, submillimeter fluxes correspond to dust masses of ∼0.5–80 Earth masses. We measure the distribution of disk sizes, and find that disks in this region are particularly compact. Such compact disks are likely to be significantly optically thick. The distributions of submillimeter flux and inferred disk size indicate smaller, lower-flux disks than in lower-density star-forming regions of similar age. Measured disk flux is correlated weakly with stellar mass, contrary to studies in other star-forming regions that found steeper correlations. We find a correlation between disk flux and distance from the massive star θ 1 Ori C, suggesting that disk properties in this region are influenced strongly by the rich cluster environment.

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

Dullo, Bililign T.; Graham, Alister W., E-mail: Bdullo@astro.swin.edu.au

We have used the full radial extent of images from the Hubble Space Telescope's Advanced Camera for Surveys and Wide Field Planetary Camera 2 to extract surface brightness profiles from a sample of six, local lenticular galaxy candidates. We have modeled these profiles using a core-Sersic bulge plus an exponential disk model. Our fast rotating lenticular disk galaxies with bulge magnitudes M{sub V} {approx}< -21.30 mag have central stellar deficits, suggesting that these bulges may have formed from ''dry'' merger events involving supermassive black holes (BHs) while their surrounding disk was subsequently built up, perhaps via cold gas accretion scenarios.more » The central stellar mass deficits M{sub def} are roughly 0.5-2 M{sub BH} (BH mass), rather than {approx}10-20 M{sub BH} as claimed from some past studies, which is in accord with core-Sersic model mass deficit measurements in elliptical galaxies. Furthermore, these bulges have Sersic indices n {approx}3, half-light radii R{sub e} < 2 kpc and masses >10{sup 11} M{sub Sun }, and therefore appear to be descendants of the compact galaxies reported at z {approx} 1.5-2. Past studies which have searched for these local counterparts by using single-component galaxy models to provide the z {approx} 0 size comparisons have overlooked these dense, compact, and massive bulges in today's early-type disk galaxies. This evolutionary scenario not only accounts for what are today generally old bulges-which must be present in z {approx} 1.5 images-residing in what are generally young disks, but it eliminates the uncomfortable suggestion of a factor of three to five growth in size for the compact, z {approx} 1.5 galaxies that are known to possess infant disks.« less

Comparative evaluation of three commercial systems for nucleic acid extraction from urine specimens.

PubMed

Tang, Yi-Wei; Sefers, Susan E; Li, Haijing; Kohn, Debra J; Procop, Gary W

2005-09-01

A nucleic acid extraction system that can handle small numbers of specimens with a short test turnaround time and short hands-on time is desirable for emergent testing. We performed a comparative validation on three systems: the MagNA Pure compact system (Compact), the NucliSens miniMAG extraction instrument (miniMAG), and the BioRobot EZ1 system (EZ1). A total of 75 urine specimens submitted for polyomavirus BK virus detection were used. The human beta-actin gene was detected on 75 (100%), 75 (100%), and 72 (96%) nucleic acid extracts prepared by the miniMAG, EZ1, and Compact, respectively. The miniMAG produced the highest quantity of nucleic acids and the best precision among the three systems. The agreement rate was 100% for BKV detection on nucleic acid extracts prepared by the three extraction systems. When a full panel of specimens was run, the hands-on time and test turnaround time were 105.7 and 121.1 min for miniMAG, 6.1 and 22.6 min for EZ1, and 7.4 and 33.7 min for Compact, respectively. The EZ1 and Compact systems processed automatic nucleic acid extraction properly, providing a good solution to the need for sporadic but emergent specimen detection. The miniMAG yielded the highest quantity of nucleic acids, suggesting that this system would be the best for specimens containing a low number of microorganisms of interest.

A POSSIBLE SIGNATURE OF LENSE-THIRRING PRECESSION IN DIPPING AND ECLIPSING NEUTRON-STAR LOW-MASS X-RAY BINARIES

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

Homan, Jeroen, E-mail: jeroen@space.mit.edu

2012-12-01

Relativistic Lense-Thirring precession of a tilted inner accretion disk around a compact object has been proposed as a mechanism for low-frequency ({approx}0.01-70 Hz) quasi-periodic oscillations (QPOs) in the light curves of X-ray binaries. A substantial misalignment angle ({approx}15 Degree-Sign -20 Degree-Sign ) between the inner-disk rotation axis and the compact-object spin axis is required for the effects of this precession to produce observable modulations in the X-ray light curve. A consequence of this misalignment is that in high-inclination X-ray binaries the precessing inner disk will quasi-periodically intercept our line of sight to the compact object. In the case of neutron-starmore » systems, this should have a significant observational effect, since a large fraction of the accretion energy is released on or near the neutron-star surface. In this Letter, I suggest that this specific effect of Lense-Thirring precession may already have been observed as {approx}1 Hz QPOs in several dipping/eclipsing neutron-star X-ray binaries.« less

Mechanical properties of human articular disk and its influence on TMJ loading studied with the finite element method.

PubMed

Tanaka, E; Sasaki, A; Tahmina, K; Yamaguchi, K; Mori, Y; Tanne, K

2001-03-01

The present study was designed to investigate the elastic modulus of human temporomandibular joint (TMJ) disk under tension and its influences on TMJ loading. Seven human TMJ disks served as specimens. Continuous tensile stress was applied to each specimen, and the elastic moduli of human TMJ disks were calculated at 2% strain. Furthermore, using a three-dimensional finite element model of the mandible including the TMJ, changes in the TMJ stresses during clenching were evaluated in association of varying elastic moduli of the articular disk determined by the tensile tests. The elastic moduli at 2% strain varied from 27.1 to 65.2 MPa with a mean of 47.1 MPa. A significant correlation was found between the elastic moduli and age (P < 0.01). On the surface of condyle, compressive stress in the anterior area and tensile stress in the posterior area increased when the elastic moduli of the TMJ disk was varied from 25 to 65 MPa. In the TMJ disk, shear stresses in all the areas became larger with greater stiffness. In conclusion, it is shown that the elastic modulus of human TMJ disk is increased with age and that higher stiffness of the disk exerts substantial influences on mechanical loading for the TMJ structures.

Nucleosynthesis inside Supernova-Driven Supercritical Accretion Disks

NASA Astrophysics Data System (ADS)

Fujimoto, Shin-Ichirou; Arai, Kenzo; Matsuba, Ryuichi; Hashimoto, Masa-Aki; Koike, Osamu; Mineshige, Shin

2001-06-01

We have investigated nucleosynthesis in a supercritical accretion disk around a compact object of 1.4Msolar, using the self-similar solution of an optically thick advection dominated flow. Supercritical accretion is expected to occur in a supernova with fallback material accreting onto a new-born compact object. It has been found that appreciable nuclear reactions take place even for a reasonable value of the viscosity parameter, αvissimeq 0.01, when the accretion rate dot{m}=dot{M}c2/(16LEdd) > 105, where LEdd is the Eddington luminosity. If dot{m} ge 4 × 106, all heavy elements are destroyed to 4He through photodisintegrations at the inner part of the disk. Even 4He is also disintegrated to protons and neutrons near the inner edge when dot{m} ge 2 × 107. If the fallback matter of the supernova explosion has the composition of a helium-rich layer of the progenitor, a considerable amount of 44Ti could be ejected via a jet from the disk.

Determining mechanical behavior of solid materials using miniature specimens

DOEpatents

Manahan, M.P.; Argon, A.S.; Harling, O.K.

1986-02-04

A Miniaturized Bend Test (MBT) capable of extracting and determining mechanical behavior information from specimens only so large as to have at least a volume or smallest dimension sufficient to satisfy continuum behavior in all directions is disclosed. The mechanical behavior of the material is determined from the measurements taken during the bending of the specimen and is processed according to the principles of linear or nonlinear material mechanics or both. In a preferred embodiment the determination is carried out by a code which is constructed according to the finite element method, and the specimen used for the determinations is a miniature disk simply supported for central loading at the axis on the center of the disk. 51 figs.

Effect of the Machining Processes on Low Cycle Fatigue Behavior of a Powder Metallurgy Disk

NASA Technical Reports Server (NTRS)

Telesman, J.; Kantzos, P.; Gabb, T. P.; Ghosn, L. J.

2010-01-01

A study has been performed to investigate the effect of various machining processes on fatigue life of configured low cycle fatigue specimens machined out of a NASA developed LSHR P/M nickel based disk alloy. Two types of configured specimen geometries were employed in the study. To evaluate a broach machining processes a double notch geometry was used with both notches machined using broach tooling. EDM machined notched specimens of the same configuration were tested for comparison purposes. Honing finishing process was evaluated by using a center hole specimen geometry. Comparison testing was again done using EDM machined specimens of the same geometry. The effect of these machining processes on the resulting surface roughness, residual stress distribution and microstructural damage were characterized and used in attempt to explain the low cycle fatigue results.

Dikir Farmasi: folk songs for health education

PubMed Central

Bahri, Salmah; Lee, Kah Seng; Adenan, Mohammad Aswady; Murugiah, Muthu Kumar; Khan, Tahir Mehmood; Neoh, Chin Fen; Long, Chiau Ming

2016-01-01

Abstract In an effort to enhance public awareness, we develop Dikir Farmasi as an innovative approach to deliver health information. Dikir Farmasi combines the elements of dikir barat (a type of traditional folk song rhythm) and traditional sketches which are popular in the state of Kelantan, Malaysia. These sketches and dikir barat rhythmic songs, with lyrics touch on issues such as drug abuse and regulation are presented in an entertaining and humorous way. Health promotion messages are disseminated using Dikir Farmasi in the form of compact disks, video compact disks, stage performance, exhibition, social media, printed media (signboard, brochure and flyer). PMID:27695527

Evolution of protoplanetary disks from their taxonomy in scattered light: Group I vs. Group II

NASA Astrophysics Data System (ADS)

Garufi, A.; Meeus, G.; Benisty, M.; Quanz, S. P.; Banzatti, A.; Kama, M.; Canovas, H.; Eiroa, C.; Schmid, H. M.; Stolker, T.; Pohl, A.; Rigliaco, E.; Ménard, F.; Meyer, M. R.; van Boekel, R.; Dominik, C.

2017-07-01

Context. High-resolution imaging reveals a large morphological variety of protoplanetary disks. To date, no constraints on their global evolution have been found from this census. An evolutionary classification of disks was proposed based on their IR spectral energy distribution, with the Group I sources showing a prominent cold component ascribed to an earlier stage of evolution than Group II. Aims: Disk evolution can be constrained from the comparison of disks with different properties. A first attempt at disk taxonomy is now possible thanks to the increasing number of high-resolution images of Herbig Ae/Be stars becoming available. Methods: Near-IR images of six Group II disks in scattered light were obtained with VLT/NACO in polarimetric differential imaging, which is the most efficient technique for imaging the light scattered by the disk material close to the stars. We compare the stellar/disk properties of this sample with those of well-studied Group I sources available from the literature. Results: Three Group II disks are detected. The brightness distribution in the disk of HD 163296 indicates the presence of a persistent ring-like structure with a possible connection with the CO snowline. A rather compact (<100 AU) disk is detected around HD 142666 and AK Sco. A taxonomic analysis of 17 Herbig Ae/Be sources reveals that the difference between Group I and Group II is due to the presence or absence of a large disk cavity (≳5 AU). There is no evidence supporting the evolution from Group I to Group II. Conclusions: Group II disks are not evolved versions of the Group I disks. Within the Group II disks, very different geometries exist (both self-shadowed and compact). HD 163296 could be the primordial version of a typical Group I disk. Other Group II disks, like AK Sco and HD 142666, could be smaller counterparts of Group I unable to open cavities as large as those of Group I. Based on observations collected at the European Organisation for Astronomical Research in the Southern Hemisphere, Chile, under program number 095.C-0658(A).

The NSO FTS database program and archive (FTSDBM)

NASA Technical Reports Server (NTRS)

Lytle, D. M.

1992-01-01

Data from the NSO Fourier transform spectrometer is being re-archived from half inch tape onto write-once compact disk. In the process, information about each spectrum and a low resolution copy of each spectrum is being saved into an on-line database. FTSDBM is a simple database management program in the NSO external package for IRAF. A command language allows the FTSDBM user to add entries to the database, delete entries, select subsets from the database based on keyword values including ranges of values, create new database files based on these subsets, make keyword lists, examine low resolution spectra graphically, and make disk number/file number lists. Once the archive is complete, FTSDBM will allow the database to be efficiently searched for data of interest to the user and the compact disk format will allow random access to that data.

NUSTAR and Suzaku x-ray spectroscopy of NGC 4151: Evidence for reflection from the inner accretion disk

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

Keck, M. L.; Brenneman, L. W.; Ballantyne, D. R.

We present X-ray timing and spectral analyses of simultaneous 150 ks Nuclear Spectroscopic Telescope Array (NuSTAR) and Suzaku X-ray observations of the Seyfert 1.5 galaxy NGC 4151. We disentangle the continuum emission, absorption, and reflection properties of the active galactic nucleus (AGN) by applying inner accretion disk reflection and absorption-dominated models. With a time-averaged spectral analysis, we find strong evidence for relativistic reflection from the inner accretion disk. We find that relativistic emission arises from a highly ionized inner accretion disk with a steep emissivity profile, which suggests an intense, compact illuminating source. We find a preliminary, near-maximal black hole spinmore » $$a\\gt 0.9$$ accounting for statistical and systematic modeling errors. We find a relatively moderate reflection fraction with respect to predictions for the lamp post geometry, in which the illuminating corona is modeled as a point source. Through a time-resolved spectral analysis, we find that modest coronal and inner disk reflection (IDR) flux variation drives the spectral variability during the observations. We discuss various physical scenarios for the IDR model and we find that a compact corona is consistent with the observed features.« less

NuSTAR and Suzaku X-ray Spectroscopy of NGC 4151: Evidence for Reflection from the Inner Accretion Disk

NASA Astrophysics Data System (ADS)

Keck, M. L.; Brenneman, L. W.; Ballantyne, D. R.; Bauer, F.; Boggs, S. E.; Christensen, F. E.; Craig, W. W.; Dauser, T.; Elvis, M.; Fabian, A. C.; Fuerst, F.; García, J.; Grefenstette, B. W.; Hailey, C. J.; Harrison, F. A.; Madejski, G.; Marinucci, A.; Matt, G.; Reynolds, C. S.; Stern, D.; Walton, D. J.; Zoghbi, A.

2015-06-01

We present X-ray timing and spectral analyses of simultaneous 150 ks Nuclear Spectroscopic Telescope Array (NuSTAR) and Suzaku X-ray observations of the Seyfert 1.5 galaxy NGC 4151. We disentangle the continuum emission, absorption, and reflection properties of the active galactic nucleus (AGN) by applying inner accretion disk reflection and absorption-dominated models. With a time-averaged spectral analysis, we find strong evidence for relativistic reflection from the inner accretion disk. We find that relativistic emission arises from a highly ionized inner accretion disk with a steep emissivity profile, which suggests an intense, compact illuminating source. We find a preliminary, near-maximal black hole spin a\\gt 0.9 accounting for statistical and systematic modeling errors. We find a relatively moderate reflection fraction with respect to predictions for the lamp post geometry, in which the illuminating corona is modeled as a point source. Through a time-resolved spectral analysis, we find that modest coronal and inner disk reflection (IDR) flux variation drives the spectral variability during the observations. We discuss various physical scenarios for the IDR model and we find that a compact corona is consistent with the observed features.

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

Kubouchi, Masatoshi; Hojo, Hidemitsu

The thermal shock resistance of epoxy resin specimens toughened with carboxy-terminated poly(butadiene-acrylonitrile) (CTBN) and poly-glycol were tested using a new notched disk-type specimen. The new thermal shock testing method consists of quenching a notched disk-type specimen and applying a theoretical analysis to the test results to determine crack propagation conditions. For both toughened epoxy resins, this test method evaluated improvements in thermal shock resistance. The thermal shock resistance of epoxy resin toughened with CTBN exhibited a maximum at a 35 parts per hundred resin content of CTBN. The epoxy resin toughened with polyglycol exhibited improved thermal shock resistance with increasingmore » glycol content. 7 refs., 14 figs., 1 tab.« less

Resolving the circumstellar environment of the B[e] star V921 Scorpii in the near-infrared with VLTI/AMBER

NASA Astrophysics Data System (ADS)

Kreplin, A.; Kraus, S.; Hofmann, K.-H.; Schertl, D.; Weigelt, G.; Driebe, T.

2012-01-01

Aims: We study the AU-scale circumstellar environment of the unclassified B[e] star V921 Sco in the near-infrared. For interpreting the observations, we employ temperature-gradient disk models. Methods: Using the near-infrared beam combiner instrument AMBER, we recorded spectrally dispersed (spectral resolution R = 35) interferograms in the H and K bands. To obtain an improved calibration of the visibilities, we developed a method that is able to equalize the histograms of the optical path difference of target and calibrator. We fit temperature-gradient disk models to the visibilities and spectral energy distribution (SED) to analyze the circumstellar dust geometry. Results: We derived a geometric ring-fit radius of 2.10 ± 0.16 mas in the K band. If we adopt the distance of 1150 ± 150 pc reported elsewhere, we obtain a ring-fit radius of 2.4 AU, which is slightly smaller than the 3.5 AU dust sublimation radius predicted by the size-luminosity relation. The fitted H-band radius of 1.61 ± 0.23 mas (1.85 AU) is found to be more compact than the K-band radius. The best-fit temperature-gradient disk model has an inner disk radius of ~1.45 AU, an inner-edge disk temperature T0 = 1533 K, and a temperature-gradient exponent q = 0.46 suggesting a flared disk geometry. Conclusions: The distance and luminosity of V921 Sco are not well known. If we assume a distance of 1150 ± 150 pc, we derive a ring-fit radius of ~2.4 AU, which is approximately consistent with the computed temperature-gradient disk model with inner and outer ring radii of 1.45 and 8.5 AU, respectively. If the inner radius of V921 Sco is more compact than the sublimation radius, this compact observed size can be explained by emitting material (e.g., a gaseous disk) inside the dust sublimation radius, as suggested for several other B[e] stars. Based on observations made with ESO telescopes at Paranal Observatory under program ID (MPG-VISA GTO): 079.C-0212(A).

Quasi-Brittle Fracture of Compact Specimens with Sharp Notches and U-Shaped Cuts

NASA Astrophysics Data System (ADS)

Kornev, V. M.; Demeshkin, A. G.

2018-01-01

A two-parameter (coupled) discrete-integral criterion of fracture is proposed. It can be used to construct fracture diagrams for compact specimens with sharp cracks. Curves separating the stress-crack length plane into three domains are plotted. These domains correspond to the absence of fracture, damage accumulation in the pre-fracture region under repeated loading, and specimen fragmentation under monotonic loading. Constants used for the analytical description of fracture diagrams for quasi-brittle materials with cracks are selected with the use of approximation of the classical stress-strain diagrams for the initial material and the critical stress intensity factor. Predictions of the proposed theory are compared with experimental results on fracture of compact specimens with different radii made of polymethylmethacrylate (PMMA) and solid rubber with crack-type effects in the form of U-shaped cuts.

Mode 1 crack surface displacements for a round compact specimen subject to a couple and force

NASA Technical Reports Server (NTRS)

Gross, B.

1979-01-01

Mode I displacement coefficients along the crack surface are presented for a radially cracked round compact specimen, treated as a plane elastostatic problem, subjected to two types of loading; a uniform tensile stress and a nominal bending stress distribution across the net section. By superposition the resultant displacement coefficient or the corresponding influence coefficient can be obtained for any practical load location. Load line displacements are presented for A/D ratios ranging from 0.40 to 0.95, where A is the crack length measured from the crack mouth to the crack tip and D is the specimen diameter. Through a linear extrapolation procedure crack mouth displacements are also obtained. Experimental evidence shows that the results are valid over the range of A/D ratios analyzed for a practical pin loaded round compact specimen.

An in vitro study of the effect of different restorative materials on the reliability of a veneering porcelain.

PubMed

Anderson, Matthew R; Chung, Kwok-Hung; Flinn, Brian D; Raigrodski, Ariel J

2013-12-01

Implant-supported, porcelain veneered restorations experience a greater rate of porcelain fracture than tooth-supported restorations. For completely edentulous patients, one approach to minimizing porcelain fracture is to use acrylic resin in the mandible, although its efficacy is unknown. The purpose of this study was to evaluate the reliability of a veneering porcelain fatigued with different restorative materials in vitro. Fifty-nine veneering porcelain disk specimens were fabricated by layering veneering porcelain on nickel-chromium base metal alloy disks. Four groups of different indenter materials fatigued the porcelain specimens: group WC, tungsten carbide served as a control; group FC, pressed leucite glass ceramic; group NHC, nanohybrid composite resin denture tooth; and group AR, unfilled acrylic resin denture tooth. Porcelain specimens were randomly divided into 4 groups (n=14). A step-stress accelerated life-testing model was used. Use-level probability Weibull plots were generated, and the reliability of each group was estimated for a theoretical completion of 50 000 cycles at 150 N. Nanohybrid composite resin and unfilled acrylic resin denture tooth groups had higher reliability than tungsten carbide and leucite glass ceramic groups. No significant differences existed between the reliability of the tungsten carbide and leucite glass ceramic groups and the nanohybrid composite resin and acrylic resin denture tooth groups. Veneering porcelain disk specimens fatigued with the unfilled acrylic resin and nanohybrid composite resin denture tooth indenters exhibited higher reliability than the specimens fatigued with either the tungsten carbide or leucite glass ceramic indenters. All of the veneering porcelain disk specimens failed with the same mode of fracture, although the surface posttest exhibited different fracture characteristics among specimens fatigued with the 4 different materials. Copyright © 2013 Editorial Council for the Journal of Prosthetic Dentistry. Published by Mosby, Inc. All rights reserved.

Specimen Holder for Analytical Electron Microscopes

NASA Technical Reports Server (NTRS)

Clanton, U. S.; Isaacs, A. M.; Mackinnon, I.

1985-01-01

Reduces spectral contamination by spurious X-ray. Specimen holder made of compressed carbon, securely retains standard electron microscope grid (disk) 3 mm in diameter and absorbs backscattered electrons that otherwise generate spurious X-rays. Since holder inexpensive, dedicated to single specimen when numerous samples examined.

Evolution of dynamo-generated magnetic fields in accretion disks around compact and young stars

NASA Technical Reports Server (NTRS)

Stepinski, Tomasz F.

1994-01-01

Geometrically thin, optically thick, turbulent accretion disks are believed to surround many stars. Some of them are the compact components of close binaries, while the others are throught to be T Tauri stars. These accretion disks must be magnetized objects because the accreted matter, whether it comes from the companion star (binaries) or from a collapsing molecular cloud core (single young stars), carries an embedded magnetic field. In addition, most accretion disks are hot and turbulent, thus meeting the condition for the MHD turbulent dynamo to maintain and amplify any seed field magnetic field. In fact, for a disk's magnetic field to persist long enough in comparison with the disk viscous time it must be contemporaneously regenerated because the characteristic diffusion time of a magnetic field is typically much shorter than a disk's viscous time. This is true for most thin accretion disks. Consequently, studying magentic fields in thin disks is usually synonymous with studying magnetic dynamos, a fact that is not commonly recognized in the literature. Progress in studying the structure of many accretion disks was achieved mainly because most disks can be regarded as two-dimensional flows in which vertical and radial structures are largely decoupled. By analogy, in a thin disk, one may expect that vertical and radial structures of the magnetic field are decoupled because the magnetic field diffuses more rapidly to the vertical boundary of the disk than along the radius. Thus, an asymptotic method, called an adiabatic approximation, can be applied to accretion disk dynamo. We can represent the solution to the dynamo equation in the form B = Q(r)b(r,z), where Q(r) describes the field distribution along the radius, while the field distribution across the disk is included in the vector function b, which parametrically depends on r and is normalized by the condition max (b(z)) = 1. The field distribution across the disk is established rapidly, while the radial distribution Q(r) evolves on a considerably longer timescale. It is this evolution that is the subject of this paper.

High surface plasmon resonance sensitivity enabled by optical disks.

PubMed

Dou, Xuan; Phillips, Blayne M; Chung, Pei-Yu; Jiang, Peng

2012-09-01

We report a systematic, experimental, and theoretical investigation on the surface plasmon resonance (SPR) sensing using optical disks with different track pitches, including Blu-ray disk (BD), digital versatile disk (DVD), and compact disk (CD). Optical reflection measurements indicate that CD and DVD exhibit much higher SPR sensitivity than BD. Both experiments and finite-difference time-domain simulations reveal that the SPR sensitivity is significantly affected by the diffraction order of the SPR peaks and higher diffraction order results in lower sensitivity. Numerical simulations also show that very high sensitivity (∼1600  nm per refractive index unit) is achievable by CDs.

Quantification of cancellous bone-compaction due to DHS Blade insertion and influence upon cut-out resistance.

PubMed

Windolf, Markus; Muths, Raphael; Braunstein, Volker; Gueorguiev, Boyko; Hänni, Markus; Schwieger, Karsten

2009-01-01

Compaction of cancellous bone is believed to prevent cut-out. This in vitro study quantified the compaction in the femoral head due to insertion of a dynamic hip screw-blade with and without predrilling and investigated the resulting implant anchorage under cyclic loading. Eight pairs of human cadaveric femoral heads were instrumented with a dynamic hip screw-blade made of Polyetheretherketon. Pairwise instrumentation was performed either with or without predrilling the specimens. CT scanning was performed before and after implantation, to measure bone-compaction. Subsequently the implant was removed and a third scan was performed to analyze the relaxation of the bone structure. Commercial implants were reinserted and the specimens were cyclically loaded until onset of cut-out occurred. The bone-implant interface was monitored by means of fluoroscopic imaging throughout the experiment. Paired t-tests were performed to identify differences regarding compaction, relaxation and cycles to failure. Bone density in the surrounding of the implant increased about 30% for the non-predrilled and 20% for the predrilled group when inserting the implant. After implant removal the predrilled specimens fully relaxed; the non-predrilled group showed about 10% plastic deformation. No differences were found regarding cycles to failure (P=0.32). Significant bone-compaction due to blade insertion was verified. Even though compaction was lower when predrilling the specimens, mainly elastic deformation was present, which is believed to primarily enhance the implant anchorage. Cyclic loading tests confirmed this thesis. The importance of the implantation technique with regard to predrilling is therefore decreased.

ALMA detection of the rotating molecular disk wind from the young star HD 163296

NASA Astrophysics Data System (ADS)

Klaassen, P. D.; Juhasz, A.; Mathews, G. S.; Mottram, J. C.; De Gregorio-Monsalvo, I.; van Dishoeck, E. F.; Takahashi, S.; Akiyama, E.; Chapillon, E.; Espada, D.; Hales, A.; Hogerheijde, M. R.; Rawlings, M.; Schmalzl, M.; Testi, L.

2013-07-01

Disk winds have been postulated as a mechanism for angular momentum release in protostellar systems for decades. HD 163296 is a Herbig Ae star surrounded by a disk and has been shown to host a series of HH knots (HH 409) with bow shocks associated with the farthest knots. Here we present ALMA science verification data of CO J = 2-1 and J = 3-2 emission, which are spatially coincident with the blue shifted jet of HH knots, and offset from the disk by -18.6 km s-1. The emission has a double corkscrew morphology and extends more than 10'' from the disk with embedded emission clumps coincident with jet knots. We interpret this double corkscrew as emission from material in a molecular disk wind, and that the compact emission near the jet knots is being heated by the jet that is moving at much higher velocities. We show that the J = 3-2 emission is likely heavily filtered by the interferometer, but the J = 2-1 emission suffers less due to the larger beam and sensitivity to larger scale structures. Excitation analysis suggests temperatures exceeding 900 K in these compact features, with the wind mass, momentum and energy being of order 10-5 M⊙, 10-4 M⊙ km s-1 and 1040 erg, respectively. The high mass loss rate suggests that this star is dispersing the disk faster than it is funneling mass onto the star.

A Survey of Compact Star Clusters in the South-West Field of the M 31 Disk

NASA Astrophysics Data System (ADS)

Kodaira, Keiichi; Vansevičius, Vladas; Bridzius, Audrius; Komiyama, Yutaka; Miyazaki, Satoshi; Stonkute, Rima; Šablevičiutė, Ieva; Narbutis, Donatas

2004-12-01

A survey for compact clusters with a dimension of 10pc order was conducted in an area of about 500 square arc-minutes of the south-west part of the M31 disk, making use of the high-resolution capability of Suprime-Cam. Photometry in the B, V, and R broad-bands, and in the R* medium-band centered around Hα with varying apertures was carried out for about 1200 targets, which are related to about 300 compact objects detected in the survey. The results for 101 prominent compact objects are presented as photometric catalogues and morphological atlases, separately for samples with and without strong Hα emission. Many of the compact objects, which were previously suspected to be globular cluster candidates, are judged to be open clusters based upon their internal structures of sub-arc-second order. The majority of the 49 listed compact non-emission objects, which are restricted to be brighter than MV ˜ -5, have colors of 0 < B - V < 1.0, indicating their nature of massive evolved clusters. In contrast, only about 10% of the 52 listed compact emission objects are brighter than MiV ˜ -5, probably reflecting the short period of the emission phase and the substantial effects of the circum-stellar extinction. The detection of a few candidates of background galaxies is also reported.

Mode I crack surface displacements for a round compact specimen subject to a couple and force

NASA Technical Reports Server (NTRS)

Gross, B.

1979-01-01

Mode I displacement coefficients along the crack surface are presented for a radially cracked round compact specimen, treated as a plane elastostatic problem, subjected to two types of loading; a uniform tensile stress and a nominal bending stress distribution across the net section. By superposition the resultant displacement coefficient or the corresponding influence coefficient can be obtained for any practical load location. Load line displacements are presented for A/D ratios ranging from 0.40 to 0.95, where A is the crack length measured from the crack mouth to the crack tip and D is the specimen diameter. Through a linear extrapolation procedure crack mouth displacements are also obtained. Experimental evidence shows that the results of this study are valid over the range of A/D ratios analyzed for a practical pin loaded round compact specimen.

Nobody Else Like Me: Activities To Celebrate Diversity.

ERIC Educational Resources Information Center

Moomaw, Sally

Based on a musical celebration of children's diversity, this early childhood curriculum guide provides guidance in using the compact disk "Nobody Else Like Me" to help children think critically about and appreciate differences and similarities among people. The guide is organized into 12 sections, each focusing on one of the songs from the disk,…

36 CFR 1235.46 - What electronic media may be used for transferring records to the National Archives of the United...

Code of Federal Regulations, 2012 CFR

2012-07-01

... that meet ANSI X3.39 or ANSI X3.54 (both incorporated by reference, see § 1235.4), respectively. (2) 18...) Compact-Disk, Read Only Memory (CD-ROM) and Digital Video Disks (DVDs). Agencies may use CD-ROMs and DVDs...

36 CFR 1235.46 - What electronic media may be used for transferring records to the National Archives of the United...

Code of Federal Regulations, 2010 CFR

2010-07-01

... that meet ANSI X3.39 or ANSI X3.54 (both incorporated by reference, see § 1235.4), respectively. (2) 18...) Compact-Disk, Read Only Memory (CD-ROM) and Digital Video Disks (DVDs). Agencies may use CD-ROMs and DVDs...

36 CFR 1235.46 - What electronic media may be used for transferring records to the National Archives of the United...

Code of Federal Regulations, 2014 CFR

2014-07-01

... that meet ANSI X3.39 or ANSI X3.54 (both incorporated by reference, see § 1235.4), respectively. (2) 18...) Compact-Disk, Read Only Memory (CD-ROM) and Digital Video Disks (DVDs). Agencies may use CD-ROMs and DVDs...

36 CFR 1235.46 - What electronic media may be used for transferring records to the National Archives of the United...

Code of Federal Regulations, 2011 CFR

2011-07-01

... that meet ANSI X3.39 or ANSI X3.54 (both incorporated by reference, see § 1235.4), respectively. (2) 18...) Compact-Disk, Read Only Memory (CD-ROM) and Digital Video Disks (DVDs). Agencies may use CD-ROMs and DVDs...

36 CFR § 1235.46 - What electronic media may be used for transferring records to the National Archives of the United...

Code of Federal Regulations, 2013 CFR

2013-07-01

...), respectively. (2) 18-track 3480-class cartridges must be recorded at 37,871 bpi that meet ANSI X3.180..., § 1235.4). (c) Compact-Disk, Read Only Memory (CD-ROM) and Digital Video Disks (DVDs). Agencies may use...

Fatigue Resistance of the Grain Size Transition Zone in a Dual Microstructure Superalloy Disk

NASA Technical Reports Server (NTRS)

Gabb, T. P.; Kantzos, P. T.; Telesman, J.; Gayda, J.; Sudbrack, C. K.; Palsa, B. S.

2010-01-01

Mechanical property requirements vary with location in nickel-based superalloy disks. To maximize the associated mechanical properties, heat treatment methods have been developed for producing tailored microstructures. In this study, a specialized heat treatment method was applied to produce varying grain microstructures from the bore to the rim portions of a powder metallurgy processed nickel-based superalloy disk. The bore of the contoured disk consisted of fine grains to maximize strength and fatigue resistance at lower temperatures. The rim microstructure of the disk consisted of coarse grains for maximum resistance to creep and dwell crack growth at high temperatures up to 704 C. However, the fatigue resistance of the grain size transition zone was unclear, and needed to be evaluated. This zone was located as a band in the disk web between the bore and rim. Specimens were extracted parallel and transverse to the transition zone, and multiple fatigue tests were performed at 427 and 704 C. Mean fatigue lives were lower at 427 C than for 704 C. Specimen failures often initiated at relatively large grains, which failed on crystallographic facets. Grain size distributions were characterized in the specimens, and related to the grains initiating failures as well as location within the transition zone. Fatigue life decreased with increasing maximum grain size. Correspondingly, mean fatigue resistance of the transition zone was slightly higher than that of the rim, but lower than that of the bore. The scatter in limited tests of replicates was comparable for all transition zone locations examined.

Comparing Sliding-Wear Characteristics of the Electro-Pressure Sintered and Wrought Cobalt

NASA Astrophysics Data System (ADS)

Lee, J. E.; Kim, Y. S.; Kim, T. W.

Dry sliding wear tests of hot-pressure sintered and wrought cobalt were carried out to compare their wear characteristics. Cobalt powders with average size of 1.5µm were electro-pressure sintered to make sintered-cobalt disk wear specimens. A vacuum-induction melted cobalt ingot was hot-rolled at 800°C to a plate, from which wrought-cobalt disk specimens were machined. The specimens were heat treated at various temperatures to vary grain size and phase fraction. Wear tests of the cobalt specimens were carried out using a pin-on-disk wear tester against a glass (83% SiO2) bead at 100N with the constant sliding speed and distance of 0.36m/s and 600m, respectively. Worn surfaces, their cross sections, and wear debris were examined by an SEM. The wear of the cobalt was found to be strongly influenced by the strain-induced phase transformation of ɛ-Co (hcp) to α-Co (fcc). The sintered cobalt had smaller uniform grain size and showed higher wear rate than the wrought cobalt. The higher wear rate of the sintered cobalt was explained by the more active deformation-induced phase transformation than in the wrought cobalt with larger irregular grains.

Dynamo magnetic field modes in thin astrophysical disks - An adiabatic computational approximation

NASA Technical Reports Server (NTRS)

Stepinski, T. F.; Levy, E. H.

1991-01-01

An adiabatic approximation is applied to the calculation of turbulent MHD dynamo magnetic fields in thin disks. The adiabatic method is employed to investigate conditions under which magnetic fields generated by disk dynamos permeate the entire disk or are localized to restricted regions of a disk. Two specific cases of Keplerian disks are considered. In the first, magnetic field diffusion is assumed to be dominated by turbulent mixing leading to a dynamo number independent of distance from the center of the disk. In the second, the dynamo number is allowed to vary with distance from the disk's center. Localization of dynamo magnetic field structures is found to be a general feature of disk dynamos, except in the special case of stationary modes in dynamos with constant dynamo number. The implications for the dynamical behavior of dynamo magnetized accretion disks are discussed and the results of these exploratory calculations are examined in the context of the protosolar nebula and accretion disks around compact objects.

Quantitative evaluation of rejuvenators to restore embrittlement temperatures in oxidized asphalt mixtures using acoustic emission

NASA Astrophysics Data System (ADS)

Sun, Zhe; Farace, Nicholas; Arnold, Jacob; Behnia, Behzad; Buttlar, William G.; Reis, Henrique

2015-03-01

Towards developing a method capable to assess the efficiency of rejuvenators to restore embrittlement temperatures of oxidized asphalt binders towards their original, i.e., unaged values, three gyratory compacted specimens were manufactured with mixtures oven-aged for 36 hours at 135 °C. In addition, one gyratory compacted specimen manufactured using a short-term oven-aged mixture for two hours at 155 °C was used for control to simulate aging during plant production. Each of these four gyratory compacted specimens was then cut into two cylindrical specimen 5 cm thick for a total of six 36-hour oven-aged specimens and two short term aging specimens. Two specimens aged for 36 hours and the two short-term specimens were then tested using an acoustic emission approach to obtain base acoustic emission response of short-term and severely-aged specimens. The remaining four specimens oven-aged for 36 hours were then treated by spreading their top surface with rejuvenator in the amount of 10% of the binder by weight. These four specimens were then tested using the same acoustic emission approach after two, four, six, and eight weeks of dwell time. It was observed that the embrittlement temperatures of the short-term aged and severely oven-aged specimens were -25 °C and - 15 °C, respectively. It was also observed that after four weeks of dwell time, the rejuvenator-treated samples had recuperated the original embrittlement temperatures. In addition, it was also observed that the rejuvenator kept acting upon the binder after four weeks of dwell time; at eight weeks of dwell time, the specimens had an embrittlement temperature about one grade cooler than the embrittlement temperature corresponding to the short-term aged specimen.

COMPACT DUST CONCENTRATION IN THE MWC 758 PROTOPLANETARY DISK

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

Marino, S.; Casassus, S.; Perez, S.

2015-11-01

The formation of planetesimals requires that primordial dust grains grow from micron- to kilometer-sized bodies. Dust traps caused by gas pressure maxima have been proposed as regions where grains can concentrate and grow fast enough to form planetesimals, before radially migrating onto the star. We report new VLA Ka and Ku observations of the protoplanetary disk around the Herbig Ae/Be star MWC 758. The Ka image shows a compact emission region in the outer disk, indicating a strong concentration of big dust grains. Tracing smaller grains, archival ALMA data in band 7 continuum shows extended disk emission with an intensitymore » maximum to the northwest of the central star, which matches the VLA clump position. The compactness of the Ka emission is expected in the context of dust trapping, as big grains are trapped more easily than smaller grains in gas pressure maxima. We develop a nonaxisymmetric parametric model inspired by a steady-state vortex solution with parameters adequately selected to reproduce the observations, including the spectral energy distribution. Finally, we compare the radio continuum with SPHERE scattered light data. The ALMA continuum spatially coincides with a spiral-like feature seen in scattered light, while the VLA clump is offset from the scattered light maximum. Moreover, the ALMA map shows a decrement that matches a region devoid of scattered polarized emission. Continuum observations at a different wavelength are necessary to conclude whether the VLA-ALMA difference is an opacity or a real dust segregation.« less

NUSTAR and SUZAKU X-ray spectroscopy of NGC 4151: Evidence for reflection from the inner accretion disk

DOE PAGES

Keck, M. L.; Brenneman, L. W.; Ballantyne, D. R.; ...

2015-06-15

We present X-ray timing and spectral analyses of simultaneous 150 ks Nuclear Spectroscopic Telescope Array (NuSTAR) and Suzaku X-ray observations of the Seyfert 1.5 galaxy NGC 4151. We disentangle the continuum emission, absorption, and reflection properties of the active galactic nucleus (AGN) by applying inner accretion disk reflection and absorption-dominated models. With a time-averaged spectral analysis, we find strong evidence for relativistic reflection from the inner accretion disk. We find that relativistic emission arises from a highly ionized inner accretion disk with a steep emissivity profile, which suggests an intense, compact illuminating source. We find a preliminary, near-maximal black hole spinmore » $$a\\gt 0.9$$ accounting for statistical and systematic modeling errors. We find a relatively moderate reflection fraction with respect to predictions for the lamp post geometry, in which the illuminating corona is modeled as a point source. Through a time-resolved spectral analysis, we find that modest coronal and inner disk reflection (IDR) flux variation drives the spectral variability during the observations. As a result, we discuss various physical scenarios for the IDR model and we find that a compact corona is consistent with the observed features.« less

NUSTAR and SUZAKU X-ray spectroscopy of NGC 4151: Evidence for reflection from the inner accretion disk

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

Keck, M. L.; Brenneman, L. W.; Ballantyne, D. R.

We present X-ray timing and spectral analyses of simultaneous 150 ks Nuclear Spectroscopic Telescope Array (NuSTAR) and Suzaku X-ray observations of the Seyfert 1.5 galaxy NGC 4151. We disentangle the continuum emission, absorption, and reflection properties of the active galactic nucleus (AGN) by applying inner accretion disk reflection and absorption-dominated models. With a time-averaged spectral analysis, we find strong evidence for relativistic reflection from the inner accretion disk. We find that relativistic emission arises from a highly ionized inner accretion disk with a steep emissivity profile, which suggests an intense, compact illuminating source. We find a preliminary, near-maximal black hole spinmore » $$a\\gt 0.9$$ accounting for statistical and systematic modeling errors. We find a relatively moderate reflection fraction with respect to predictions for the lamp post geometry, in which the illuminating corona is modeled as a point source. Through a time-resolved spectral analysis, we find that modest coronal and inner disk reflection (IDR) flux variation drives the spectral variability during the observations. As a result, we discuss various physical scenarios for the IDR model and we find that a compact corona is consistent with the observed features.« less

Development of a low loss magnetic composite utilizing amorphous metal flake. Second semi-annual progress report, March 19-September 18, 1979

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

Not Available

1979-10-01

Composite specimens of amorphous metal flakes have been made using several different binders and several different compaction parameters. The binders have included epoxies, anaerobic adhesives, polyimides, polyamideimides, polyeherimides, and polyesterimides. Compaction variables included the time, temperature and pressure of compaction; flake size, and flake alignment. The best results were achieved using a polyetherimide and aligned flake. Packing factors of 87% were achieved in specimens which also exhibited high mechanical integrity and the ability to withstand a high temperature anneal.

Orbital Evolution of Moons in Weakly Accreting Circumplanetary Disks

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

Fujii, Yuri I.; Gressel, Oliver; Kobayashi, Hiroshi

We investigate the formation of hot and massive circumplanetary disks (CPDs) and the orbital evolution of satellites formed in these disks. Because of the comparatively small size-scale of the sub-disk, quick magnetic diffusion prevents the magnetorotational instability (MRI) from being well developed at ionization levels that would allow MRI in the parent protoplanetary disk. In the absence of significant angular momentum transport, continuous mass supply from the parental protoplanetary disk leads to the formation of a massive CPD. We have developed an evolutionary model for this scenario and have estimated the orbital evolution of satellites within the disk. We find,more » in a certain temperature range, that inward migration of a satellite can be stopped by a change in the structure due to the opacity transitions. Moreover, by capturing second and third migrating satellites in mean motion resonances, a compact system in Laplace resonance can be formed in our disk models.« less

OUTWARD MOTION OF POROUS DUST AGGREGATES BY STELLAR RADIATION PRESSURE IN PROTOPLANETARY DISKS

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

Tazaki, Ryo; Nomura, Hideko, E-mail: rtazaki@kusastro.kyoto-u.ac.jp

2015-02-01

We study the dust motion at the surface layer of protoplanetary disks. Dust grains in the surface layer migrate outward owing to angular momentum transport via gas-drag force induced by the stellar radiation pressure. In this study we calculate the mass flux of the outward motion of compact grains and porous dust aggregates by the radiation pressure. The radiation pressure force for porous dust aggregates is calculated using the T-Matrix Method for the Clusters of Spheres. First, we confirm that porous dust aggregates are forced by strong radiation pressure even if they grow to be larger aggregates, in contrast tomore » homogeneous and spherical compact grains, for which radiation pressure efficiency becomes lower when their sizes increase. In addition, we find that the outward mass flux of porous dust aggregates with monomer size of 0.1 μm is larger than that of compact grains by an order of magnitude at the disk radius of 1 AU, when their sizes are several microns. This implies that large compact grains like calcium-aluminum-rich inclusions are hardly transported to the outer region by stellar radiation pressure, whereas porous dust aggregates like chondritic-porous interplanetary dust particles are efficiently transported to the comet formation region. Crystalline silicates are possibly transported in porous dust aggregates by stellar radiation pressure from the inner hot region to the outer cold cometary region in the protosolar nebula.« less

Evidence for disks at an early stage in class 0 protostars?

NASA Astrophysics Data System (ADS)

Gerin, M.; Pety, J.; Commerçon, B.; Fuente, A.; Cernicharo, J.; Marcelino, N.; Ciardi, A.; Lis, D. C.; Roueff, E.; Wootten, H. A.; Chapillon, E.

2017-10-01

Aims: The formation epoch of protostellar disks is debated because of the competing roles of rotation, turbulence, and magnetic fields in the early stages of low-mass star formation. Magnetohydrodynamics simulations of collapsing cores predict that rotationally supported disks may form in strongly magnetized cores through ambipolar diffusion or misalignment between the rotation axis and the magnetic field orientation. Detailed studies of individual sources are needed to cross check the theoretical predictions. Methods: We present 0.06-0.1'' resolution images at 350 GHz toward B1b-N and B1b-S, which are young class 0 protostars, possibly first hydrostatic cores. The images have been obtained with ALMA, and we compare these data with magnetohydrodynamics simulations of a collapsing turbulent and magnetized core. Results: The submillimeter continuum emission is spatially resolved by ALMA. Compact structures with optically thick 350 GHz emission are detected toward both B1b-N and B1b-S, with 0.2 and 0.35'' radii (46 and 80 au at the Perseus distance of 230 pc), within a more extended envelope. The flux ratio between the compact structure and the envelope is lower in B1b-N than in B1b-S, in agreement with its earlier evolutionary status. The size and orientation of the compact structure are consistent with 0.2'' resolution 32 GHz observations obtained with the Very Large Array as a part of the VANDAM survey, suggesting that grains have grown through coagulation. The morphology, temperature, and densities of the compact structures are consistent with those of disks formed in numerical simulations of collapsing cores. Moreover, the properties of B1b-N are consistent with those of a very young protostar, possibly a first hydrostatic core. These observations provide support for the early formation of disks around low-mass protostars. The reduced images and datacubes are only available at the CDS via anonymous ftp to http://cdsarc.u-strasbg.fr (http://130.79.128.5) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/606/A35

Spectral evolution in young active galactic nuclei

NASA Technical Reports Server (NTRS)

Boldt, E.; Leiter, D.

1986-01-01

The spectral evolution of AGNs is discussed within the context of a scenario where the cosmic X-ray background (CXB) is dominated by these sources. Attention is draqwn to the fact that the individually observed AGN X-ray spectra are significantly steeper than that of the CXB. The remarkably flat spectrum thereby required for the 'as-yet' unresolved sources of the residual CXB is interpreted as an observational constraint on an earlier stage of AGN evolution. Assuming black hole disk accretion, a picture emerges where young AGNs are compact Eddington limited thermal X-ray sources and where canonical AGNs represent later stages in which they have become appreciably less compact, exhibiting the importance of nonthermal disk-dynamo processes.

Development of Planar Optics for an Optical Tracking Sensor

NASA Astrophysics Data System (ADS)

Kawano, Hiroyuki; Sasagawa, Tomohiro

1998-10-01

An optical tracking sensor for large-capacity flexible disk drive (FDD) is demonstrated. The passive optics is compact and lightweight (5.4 mm length×3.6 mm width×1.2 mm height in size and 18 mg weight). It comprises all passive optical elements necessary for optical tracking, e.g., a focusing lens, a three-beam grating, an aperture and a beam splitter grating. Three beams were focused to a predetermined spot size of 13 µm at designed intervals of 110 µm on a disk surface and the reflected beams were successfully guided to photodiodes. This confirms that the application of the planar optical technique is very useful for realizing a compact and light optical sensor.

Analysis of laboratory compaction methods of roller compacted concrete

NASA Astrophysics Data System (ADS)

Trtík, Tomáš; Chylík, Roman; Bílý, Petr; Fládr, Josef

2017-09-01

Roller-Compacted Concrete (RCC) is an ordinary concrete poured and compacted with machines typically used for laying of asphalt road layers. One of the problems connected with this technology is preparation of representative samples in the laboratory. The aim of this work was to analyse two methods of preparation of RCC laboratory samples with bulk density as the comparative parameter. The first method used dynamic compaction by pneumatic hammer. The second method of compaction had a static character. The specimens were loaded by precisely defined force in laboratory loading machine to create the same conditions as during static rolling (in the Czech Republic, only static rolling is commonly used). Bulk densities obtained by the two compaction methods were compared with core drills extracted from real RCC structure. The results have shown that the samples produced by pneumatic hammer tend to overestimate the bulk density of the material. For both compaction methods, immediate bearing index test was performed to verify the quality of compaction. A fundamental difference between static and dynamic compaction was identified. In static compaction, initial resistance to penetration of the mandrel was higher, after exceeding certain limit the resistance was constant. This means that the samples were well compacted just on the surface. Specimens made by pneumatic hammer actively resisted throughout the test, the whole volume was uniformly compacted.

Introduction of the hybcell-based compact sequencing technology and comparison to state-of-the-art methodologies for KRAS mutation detection.

PubMed

Zopf, Agnes; Raim, Roman; Danzer, Martin; Niklas, Norbert; Spilka, Rita; Pröll, Johannes; Gabriel, Christian; Nechansky, Andreas; Roucka, Markus

2015-03-01

The detection of KRAS mutations in codons 12 and 13 is critical for anti-EGFR therapy strategies; however, only those methodologies with high sensitivity, specificity, and accuracy as well as the best cost and turnaround balance are suitable for routine daily testing. Here we compared the performance of compact sequencing using the novel hybcell technology with 454 next-generation sequencing (454-NGS), Sanger sequencing, and pyrosequencing, using an evaluation panel of 35 specimens. A total of 32 mutations and 10 wild-type cases were reported using 454-NGS as the reference method. Specificity ranged from 100% for Sanger sequencing to 80% for pyrosequencing. Sanger sequencing and hybcell-based compact sequencing achieved a sensitivity of 96%, whereas pyrosequencing had a sensitivity of 88%. Accuracy was 97% for Sanger sequencing, 85% for pyrosequencing, and 94% for hybcell-based compact sequencing. Quantitative results were obtained for 454-NGS and hybcell-based compact sequencing data, resulting in a significant correlation (r = 0.914). Whereas pyrosequencing and Sanger sequencing were not able to detect multiple mutated cell clones within one tumor specimen, 454-NGS and the hybcell-based compact sequencing detected multiple mutations in two specimens. Our comparison shows that the hybcell-based compact sequencing is a valuable alternative to state-of-the-art methodologies used for detection of clinically relevant point mutations.

A mid-IR interferometric survey with MIDI/VLTI: resolving the second-generation protoplanetary disks around post-AGB binaries

NASA Astrophysics Data System (ADS)

Hillen, M.; Van Winckel, H.; Menu, J.; Manick, R.; Debosscher, J.; Min, M.; de Wit, W.-J.; Verhoelst, T.; Kamath, D.; Waters, L. B. F. M.

2017-03-01

Aims: We present a mid-IR interferometric survey of the circumstellar environment of a specific class of post-asymptotic giant branch (post-AGB) binaries. For this class the presence of a compact dusty disk has been postulated on the basis of various spatially unresolved measurements. The aim is to determine the angular extent of the N-band emission directly and to resolve the compact circumstellar structures. Methods: Our interferometric survey was performed with the MIDI instrument on the VLTI. In total 19 different systems were observed using variable baseline configurations. Combining all the visibilities at a single wavelength at 10.7 μm, we fitted two parametric models to the data: a uniform disk and a ring model mimicking a temperature gradient. We compared our observables of the whole sample, with synthetic data computed from a grid of radiative transfer models of passively irradiated disks in hydrostatic equilibrium. These models are computed with a Monte Carlo code that has been widely applied to describe the structure of protoplanetary disks around young stellar objects (YSO). Results: The spatially resolved observations show that the majority of our targets cluster closely together in the distance-independent size-colour diagram, and have extremely compact N-band emission regions. The typical uniform disk diameter of the N-band emission region is 40 mas, which corresponds to a typical brightness temperature of 400-600 K. The resolved objects display very similar characteristics in the interferometric observables and in the spectral energy distributions. Therefore, the physical properties of the disks around our targets must be similar. Our results are discussed in the light of recently published sample studies of YSOs to compare quantitatively the secondary discs around post-AGB stars to the ones around YSOs. Conclusions: Our high-angular-resolution survey further confirms the disk nature of the circumstellar structures present around wide post-AGB binaries. The grid of protoplanetary disk models covers very well the observed objects. Much like for young stars, the spatially resolved N-band emission region is determined by the hot inner rim of the disk. Continued comparisons between post-AGB and protoplanetary disks will help to understand grain growth and disk evolution processes, and to constrain planet formation theories. These second-generation disks are an important missing ingredient in binary evolution theory of intermediate-mass stars. Based on observations made with ESO Telescopes at the La Silla Paranal Observatory under programmes ID 073.A-9002, 073.A-9014, 073.D-0610, 075.D-0605, 077.D-0071, 078.D-0113, 079.D-0013, 080.D-0059, 081.D-0089, 082.D-0066, 083.D-0011, 083.D-0013, 084.D-0009, 093.D-0914, and 094.D-0778. Some observations were obtained in the framework of the Belgian Guaranteed Time allocation on VISA.

Effects of asphalt rejuvenator on thermal and mechanical properties on oxidized hot mixed asphalt pavements

NASA Astrophysics Data System (ADS)

Farace, Nicholas A.; Buttlar, William G.; Reis, Henrique

2016-04-01

The utilization of asphalt rejuvenator, and its effectiveness for restoring thermal and mechanical properties was investigated via Disk-shaped Compact Tension (DC(T)) and acoustic emission (AE) testing for determining mechanical properties and embrittlement temperatures of the mixtures. During the DC(T) testing the fracture energies and peak loads were used to measure the resistance of the rejuvenated asphalt to low temperature cracking. The AE testing monitored the acoustic emission activity while the specimens were cooled from room temperature to -40 °C to estimate the temperature at which thermal cracking began (i.e. the embrittlement temperature). First, a baseline response was obtained by obtaining the mechanical and thermal response of virgin HMA samples and HMA samples that had been exposed to oxidative aging for 36 hours at 135°C. The results showed the virgin samples had much higher peak loads and fracture energies than the 36 hours aged samples. Acoustic Emission showed similar results with the virgin samples having embrittlement temperatures 10 °C cooler than the 36 hours aged specimens. Then, overaged for 36 hours specimens were treated different amounts of rejuvenator (10%, 15%, and 20% by weight of binder content) and left to dwell for increased amount of time periods varying from one to eight weeks. It was observed that the AE results showed an improvement of embrittlement temperature with increasing with the dwell times. The 8 weeks specimens had cooler embrittlement temperatures than the virgin specimens. Finally, the low temperature effects on fracture energy and peak load of the rejuvenated asphalt was investigated. Rejuvenator was applied (10% by weight of binder) to specimens aged 36 hours at 135 °C, and the dwell time was varied from 1 to 4 weeks. The results showed that the peak loads were restored to levels of the virgin specimens, and the fracture energies improved to levels beyond that of the virgin specimens. The results also showed a general trend of improvement for the AE testing of the embrittlement temperature.

Comparison of different techniques for obturating experimental internal resorptive cavities.

PubMed

Goldberg, F; Massone, E J; Esmoris, M; Alfie, D

2000-06-01

Forty extracted maxillary central incisors were instrumented at the working length to a #50 file. The roots were sectioned transversely with a diamond disk at 7 mm from the anatomical apex. At the opening of the root canal of each section, hemicircular cavities were drilled with a specially designed bur. The corresponding root sections were cemented with glue, thus obtaining root canals with similar cavities that simulated internal resorptions. Teeth were embedded in plaster casts to facilitate their handling. The specimens were randomly separated into four groups of 10. The following obturation techniques were evaluated: lateral compaction (group A), hybrid technique (group B), Obtura II (group C), and Thermafil (group D). AH26 was used as the sealer. After obturation, the plaster was removed and the teeth were radiographed in buccolingual and mesiodistal directions to evaluate the quality of the obturation at the IRC. The incisors were then cut with a scalpel at the same level as the previous section, to examine, under a stereomicroscope, the type of material that filled the IRC. Obtura II gave the best results and in most of the specimens obturated with this technique, the IRC were filled mainly with gutta-percha. Statistical analysis of the data indicated that the differences between group C and the other groups were significant (P < 0.05).

Comparison of different grinding procedures on the flexural strength of zirconia.

PubMed

Işeri, Ufuk; Ozkurt, Zeynep; Yalnız, Ayşe; Kazazoğlu, Ender

2012-05-01

The surface of zirconia ceramic is damaged during grinding, which may affect the mechanical properties of the material. The purpose of this study was to compare the biaxial flexural strength of zirconia after different grinding procedures and to measure the temperature rise from grinding. Forty disk-shaped zirconia specimens (15 × 1.2 mm) with a smaller disk in the center of each disk (1 × 3 mm) were divided into 4 groups (n=10). The specimens were ground with a high-speed handpiece and micromotor with 2 different grinding protocols, continual grinding and periodic grinding (10 seconds grinding with 10 seconds duration), until the smaller disk was removed. Control specimens without the center disk (n=10) were analyzed without grinding. The biaxial flexural strengths of the disks were determined in a universal testing machine at a crosshead speed of 0.5 mm/min. The fracture strength (MPa) was recorded, and the results were analyzed using a 1-way ANOVA, Tukey HSD test, Student's t test, and Pearson correlation test (α=05). All grinding procedures significantly decreased flexural strength (P<.01). The mean flexural strength of the high-speed handpiece groups was higher (815 MPa) than that of the micromotor groups (718 MPa). The temperature values obtained from micromotor grinding (127°C) were significantly higher than those from high-speed handpiece grinding (63°C) (P<.01). Grinding zirconia decreased flexural strength. Zirconia material ground with a high-speed handpiece run continually caused the least reduction in flexural strength. Copyright © 2012 The Editorial Council of the Journal of Prosthetic Dentistry. Published by Mosby, Inc. All rights reserved.

Characterization of fatigue crack initiation and propagation in Ti-6Al-4V with electrical potential drop technique

NASA Technical Reports Server (NTRS)

Kalluri, Sreeramesh; Telesman, Jack

1988-01-01

Electrical potential methods have been used in the past primarily to monitor crack length in long crack specimens subjected to fatigue loading. An attempt was made to develop test procedures for monitoring the fatigue crack initiation and the growth of short fatigue cracks in a turbine disk alloy with the electrical potential drop technique (EPDT). In addition, the EPDT was also applied to monitor the fatigue crack growth in long crack specimens of the same alloy. The resolution of the EPDT for different specimen geometries was determined. Factors influencing the EPDT are identified and the applicability of EPDT in implementing damage tolerant design concepts for turbine disk materials is discussed. The experimental procedure adopted and the results obtained is discussed. No substantial differences were observed between the fatigue crack growth data of short and long crack specimens.

Edge softening of the Shuttle TPS strain isolation pad. [Thermal Protection System

NASA Technical Reports Server (NTRS)

Ransone, P. O.; Rummler, D. R.

1982-01-01

Tensile tests and an analytical investigation were performed to characterize the edge softening behavior of the strain isolation pad (SIP) between the Orbiter skin and thermal protection system. The tensile tests were carried out with varying sizes of disk-shaped specimens bonded between aluminum disks. The specimens strength and stiffness were determined on the basis of specimen size, and an analytical model of the microstructural stress-strain characteristics was developed. Strength and stiffness were found to decrease near the free edges because through-the-thickness fibers located there were not anchored. No size dependence at maximum load was observed in specimens between 0.75-4.0 in. thick. In-plane and out-of-plane coupling in deformation was detected. The model gave accurate predictions of the tensile behavior of the SIP as a function of distance to a free edge.

Load apparatus and method for bolt-loaded compact tension test specimen

DOEpatents

Buescher, B.J. Jr.; Lloyd, W.R.; Ward, M.B.; Epstein, J.S.

1997-02-04

A bolt-loaded compact tension test specimen load apparatus includes: (a) a body having first and second opposing longitudinal ends, the first end comprising an externally threaded portion sized to be threadedly received within the test specimen threaded opening; (b) a longitudinal loading rod having first and second opposing longitudinal ends, the loading rod being slidably received in a longitudinal direction within the body internally through the externally threaded portion and slidably extending longitudinally outward of the body first longitudinal end; (c) a force sensitive transducer slidably received within the body and positioned to engage relative to the loading rod second longitudinal end; and (d) a loading bolt threadedly received relative to the body, the loading bolt having a bearing end surface and being positioned to bear against the transducer to forcibly sandwich the transducer between the loading bolt and loading rod. Also disclosed is a method of in situ determining applied force during crack propagation in a bolt-loaded compact tension test specimen. 6 figs.

Load apparatus and method for bolt-loaded compact tension test specimen

DOEpatents

Buescher, Jr., Brent J.; Lloyd, W. Randolph; Ward, Michael B.; Epstein, Jonathan S.

1997-01-01

A bolt-loaded compact tension test specimen load apparatus includes: a) a body having first and second opposing longitudinal ends, the first end comprising an externally threaded portion sized to be threadedly received within the test specimen threaded opening; b) a longitudinal loading rod having first and second opposing longitudinal ends, the loading rod being slidably received in a longitudinal direction within the body internally through the externally threaded portion and slidably extending longitudinally outward of the body first longitudinal end; c) a force sensitive transducer slidably received within the body and positioned to engage relative to the loading rod second longitudinal end; and d) a loading bolt threadedly received relative to the body, the loading bolt having a bearing end surface and being positioned to bear against the transducer to forcibly sandwich the transducer between the loading bolt and loading rod. Also disclosed is a method of in situ determining applied force during crack propagation in a bolt-loaded compact tension test specimen.

DETECTION OF STRONG MILLIMETER EMISSION FROM THE CIRCUMSTELLAR DUST DISK AROUND V1094 SCO: COLD AND MASSIVE DISK AROUND A T TAURI STAR IN A QUIESCENT ACCRETION PHASE?

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

Tsukagoshi, Takashi; Kohno, Kotaro; Saito, Masao

2011-01-01

We present the discovery of a cold massive dust disk around the T Tauri star V1094 Sco in the Lupus molecular cloud from the 1.1 mm continuum observations with AzTEC on ASTE. A compact (r{approx}< 320 AU) continuum emission coincides with the stellar position having a flux density of 272 mJy, which is the largest among T Tauri stars in Lupus. We also present the detection of molecular gas associated with the star in the five-point observations in {sup 12}CO J = 3-2 and {sup 13}CO J = 3-2. Since our {sup 12}CO and {sup 13}CO observations did not showmore » any signature of a large-scale outflow or a massive envelope, the compact dust emission is likely to come from a disk around the star. The observed spectral energy distribution (SED) of V1094 Sco shows no distinct turnover from near-infrared to millimeter wavelengths, can be well described by a flattened disk for the dust component, and no clear dip feature around 10 {mu}m suggestive of the absence of an inner hole in the disk. We fit a simple power-law disk model to the observed SED. The estimated disk mass ranges from 0.03 M{sub sun} to {approx}>0.12 M{sub sun}, which is one or two orders of magnitude larger than the median disk mass of T Tauri stars in Taurus. The resultant temperature is lower than that of a flared disk with well-mixed dust in hydrostatic equilibrium and is probably attributed to the flattened disk geometry for the dust which the central star cannot illuminate efficiently. From these results, together with the fact that there is no signature of an inner hole in the SED, we suggest that the dust grains in the disk around V1094 Sco sank into the midplane with grain growth by coalescence and are in the evolutional stage just prior to or at the formation of planetesimals.« less

Stress-intensity factors and crack-opening displacements for round compact specimens. [fracture toughness of metallic materials

NASA Technical Reports Server (NTRS)

Newman, J. C., Jr.

1979-01-01

A two dimensional, boundary collocation stress analysis was used to analyze various round compact specimens. The influence of the round external boundary and of pin-loaded holes on stress intensity factors and crack opening displacements was determined as a function of crack-length-to-specimen-width ratios. A wide-range equation for the stress intensity factors was developed. Equations for crack-surface displacements and load-point displacements were also developed. In addition, stress intensity factors were calculated from compliance methods to demonstrate that load-displacement records must be made at the loading points and not along the crack line for crack-length-to-specimen-width ratios less than about 0.4.

Laser radiation at various wavelengths for decompression of intervertebral disk. Experimental observations on human autopsy specimens.

PubMed

Choy, D S; Altman, P A; Case, R B; Trokel, S L

1991-06-01

The interaction of laser radiation with the nucleus pulposus from autopsy specimens of human intervertebral disks was evaluated at different wavelengths (193 nm, 488 nm & 514 nm, 1064 nm, 1318 nm, 2150 nm, 2940 nm, and 10600 nm). A significant correlation of linear least squares fit of the mass ablated as a function of incident energy was found for all lasers used except the Excimer at 193 nm. The 2940-nm Erbium:YAG laser was most efficient in terms of mass of disk ablated per joule in the limited lower range where this wavelength was observed. At higher energy levels, the CO2 laser in the pulsed mode was most efficient. However, the Nd:YAG 1064-nm and 1318-nm lasers are currently best suited for percutaneous laser disk decompression because of the availability of usable waveguides. Carbonization of tissue with the more penetrating Nd:YAG 1064-nm laser increases the efficiency of tissue ablation and makes it comparable to the Nd:YAG 1318-nm laser.

Effect of end-point compaction on superpave hot mix asphalt (HMA) mix designs.

DOT National Transportation Integrated Search

2004-01-09

In the Superpave hot mix asphalt (HMA) mix design system, gyratory specime ns are compacted to varying levels of initial (Ninitial), : design (Ndesign) and maximum (Nmaximum) gyrations. Initially, in the Superpave system, specimens were compacted to ...

Protocol dependence of mechanical properties in granular systems.

PubMed

Inagaki, S; Otsuki, M; Sasa, S

2011-11-01

We study the protocol dependence of the mechanical properties of granular media by means of computer simulations. We control a protocol of realizing disk packings in a systematic manner. In 2D, by keeping material properties of the constituents identical, we carry out compaction with various strain rates. The disk packings exhibit the strain rate dependence of the critical packing fraction above which the pressure becomes non-zero. The observed behavior contrasts with the well-studied jamming transitions for frictionless disk packings. We also observe that the elastic moduli of the disk packings depend on the strain rate logarithmically. Our results suggest that there exists a time-dependent state variable to describe macroscopic material properties of disk packings, which depend on its protocol.

The use of computerized image guidance in lumbar disk arthroplasty.

PubMed

Smith, Harvey E; Vaccaro, Alexander R; Yuan, Philip S; Papadopoulos, Stephen; Sasso, Rick

2006-02-01

Surgical navigation systems have been increasingly studied and applied in the application of spinal instrumentation. Successful disk arthroplasty requires accurate midline and rotational positioning for optimal function and longevity. A surgical simulation study in human cadaver specimens was done to evaluate and compare the accuracy of standard fluoroscopy, computer-assisted fluoroscopic image guidance, and Iso-C3D image guidance in the placement of lumbar intervertebral disk replacements. Lumbar intervertebral disk prostheses were placed using three different image guidance techniques in three human cadaver spine specimens at multiple levels. Postinstrumentation accuracy was assessed with thin-cut computed tomography scans. Intervertebral disk replacements placed using the StealthStation with Iso-C3D were more accurately centered than those placed using the StealthStation with FluoroNav and standard fluoroscopy. Intervertebral disk replacements placed with Iso-C3D and FluoroNav had improved rotational divergence compared with standard fluoroscopy. Iso-C3D and FluoroNav had a smaller interprocedure variance than standard fluoroscopy. These results did not approach statistical significance. Relative to both virtual and standard fluoroscopy, use of the StealthStation with Iso-C3D resulted in improved accuracy in centering the lumbar disk prosthesis in the coronal midline. The StealthStation with FluoroNav appears to be at least equivalent to standard fluoroscopy and may offer improved accuracy with rotational alignment while minimizing radiation exposure to the surgeon. Surgical guidance systems may offer improved accuracy and less interprocedure variation in the placement of intervertebral disk replacements than standard fluoroscopy. Further study regarding surgical navigation systems for intervertebral disk replacement is warranted.

Use of an ultrasonic device for the determination of elastic modulus of dentin.

PubMed

Miyazaki, Masashi; Inage, Hirohiko; Onose, Hideo

2002-03-01

The mechanical properties of dentin substrate are one of the important factors in determining bond strength of dentin bonding systems. The purpose of this study was to determine the elastic modulus of dentin substrate with the use of an ultrasonic device. The dentin disks of about 1 mm thickness were obtaining from freshly extracted human third molars, and the dentin disk was shaped in a rectangular form with a line diamond point. The size and weight of each specimen was measured to calculate the density of the specimen. The ultrasonic equipment employed in this study was composed of a Pulser-Receiver (Model 5900PR, Panametrics), transducers (V155, V156, Panametrics) and an oscilloscope. The measured two-way transit time through the dentin disk was divided by two to account for the down-and-back travel path, and then multiplied by the velocity of sound in the test material. Measuring the longitudinal and share wave sound velocity determine elastic modulus. The mean elastic modulus of horizontally sectioned specimens was 21.8 GPa and 18.5 GPa for the vertically sectioned specimens, and a significant difference was found between the two groups. The ultrasonic method used in this study shows considerable promise for determination of the elastic modulus of the tooth substrate.

On the Relative Relevance of Subject-Specific Geometries and Degeneration-Specific Mechanical Properties for the Study of Cell Death in Human Intervertebral Disk Models

PubMed Central

Malandrino, Andrea; Pozo, José M.; Castro-Mateos, Isaac; Frangi, Alejandro F.; van Rijsbergen, Marc M.; Ito, Keita; Wilke, Hans-Joachim; Dao, Tien Tuan; Ho Ba Tho, Marie-Christine; Noailly, Jérôme

2015-01-01

Capturing patient- or condition-specific intervertebral disk (IVD) properties in finite element models is outmost important in order to explore how biomechanical and biophysical processes may interact in spine diseases. However, disk degenerative changes are often modeled through equations similar to those employed for healthy organs, which might not be valid. As for the simulated effects of degenerative changes, they likely depend on specific disk geometries. Accordingly, we explored the ability of continuum tissue models to simulate disk degenerative changes. We further used the results in order to assess the interplay between these simulated changes and particular IVD morphologies, in relation to disk cell nutrition, a potentially important factor in disk tissue regulation. A protocol to derive patient-specific computational models from clinical images was applied to different spine specimens. In vitro, IVD creep tests were used to optimize poro-hyperelastic input material parameters in these models, in function of the IVD degeneration grade. The use of condition-specific tissue model parameters in the specimen-specific geometrical models was validated against independent kinematic measurements in vitro. Then, models were coupled to a transport-cell viability model in order to assess the respective effects of tissue degeneration and disk geometry on cell viability. While classic disk poro-mechanical models failed in representing known degenerative changes, additional simulation of tissue damage allowed model validation and gave degeneration-dependent material properties related to osmotic pressure and water loss, and to increased fibrosis. Surprisingly, nutrition-induced cell death was independent of the grade-dependent material properties, but was favored by increased diffusion distances in large IVDs. Our results suggest that in situ geometrical screening of IVD morphology might help to anticipate particular mechanisms of disk degeneration. PMID:25717471

Thermal and Mechanical Property Characterization of the Advanced Disk Alloy LSHR

NASA Technical Reports Server (NTRS)

Gabb, Timothy P.; Gayda, John; Telesman, Jack; Kantzos, Peter T.

2005-01-01

A low solvus, high refractory (LSHR) powder metallurgy disk alloy was recently designed using experimental screening and statistical modeling of composition and processing variables on sub-scale disks to have versatile processing-property capabilities for advanced disk applications. The objective of the present study was to produce a scaled-up disk and apply varied heat treat processes to enable full-scale demonstration of LSHR properties. Scaled-up disks were produced, heat treated, sectioned, and then machined into specimens for mechanical testing. Results indicate the LSHR alloy can be processed to produce fine and coarse grain microstructures with differing combinations of strength and time-dependent mechanical properties, for application at temperatures exceeding 1300 F.

Thermo-Rotational Instability in Plasma Disks Around Compact Objects*

NASA Astrophysics Data System (ADS)

Coppi, Bruno

2008-04-01

Differentially rotating plasma disks, around compact objects, that are imbedded in a ``seed'' magnetic field are shown to develop vertically localized ballooning modes that are driven by the combined radial gradient of the rotation frequency and the vertical gradients of the plasma density and temperature [1]. When the electron mean free path is shorter than the disk height and the (vertical) thermal conductivity can be neglected, the vertical particle flows produced by of these modes have the effect to drive the density and temperature profiles toward the ``adiabatic condition'' where ηT≡(dlnT/dz/(dlnn/dz)=2/3. Here T is the plasma temperature and n the particle density. The faster growth rates correspond to steeper temperature profiles (ηT>2/3) such as those produced by an internal (e.g. viscous) heating process. In the end, ballooning modes excited for various values of ηT can lead to the evolution of the disk into a different current carrying configuration such as a sequence of plasma rings[2].*Sponsored in part by the U.S. Department of Energy[1]B. Coppi, M.I.T. (LNS) Report HEP, 07/02, Cambridge, MA (2007), Invited Paper at the International Symposium on ``Momentum Transport in Jets, Disks and Laboratory Plasmas'', Alba, Piedmont, September 2007, to be published in Europhysical Letters (EPL, IOP)[2]B. Coppi andF. Rousseau, Ap. J., 641, 458, (2006)

Progress In Optical Memory Technology

NASA Astrophysics Data System (ADS)

Tsunoda, Yoshito

1987-01-01

More than 20 years have passed since the concept of optical memory was first proposed in 1966. Since then considerable progress has been made in this area together with the creation of completely new markets of optical memory in consumer and computer application areas. The first generation of optical memory was mainly developed with holographic recording technology in late 1960s and early 1970s. Considerable number of developments have been done in both analog and digital memory applications. Unfortunately, these technologies did not meet a chance to be a commercial product. The second generation of optical memory started at the beginning of 1970s with bit by bit recording technology. Read-only type optical memories such as video disks and compact audio disks have extensively investigated. Since laser diodes were first applied to optical video disk read out in 1976, there have been extensive developments of laser diode pick-ups for optical disk memory systems. The third generation of optical memory started in 1978 with bit by bit read/write technology using laser diodes. Developments of recording materials including both write-once and erasable have been actively pursued at several research institutes. These technologies are mainly focused on the optical memory systems for computer application. Such practical applications of optical memory technology has resulted in the creation of such new products as compact audio disks and computer file memories.

Shear fatigue crack growth - A literature survey

NASA Technical Reports Server (NTRS)

Liu, H. W.

1985-01-01

Recent studies of shear crack growth are reviewed, emphasizing test methods and data analyses. The combined mode I and mode II elastic crack tip stress fields are considered. The development and design of the compact shear specimen are described, and the results of fatigue crack growth tests using compact shear specimens are reviewed. The fatigue crack growth tests are discussed and the results of inclined cracks in tensile panels, center cracks in plates under biaxial loading, cracked beam specimens with combined bending and shear loading, center-cracked panels and double edge-cracked plates under cyclic shear loading are examined and analyzed in detail.

Development of indirect ring tension test for fracture characterization of asphalt mixtures

NASA Astrophysics Data System (ADS)

Zeinali Siavashani, Alireza

Low temperature cracking is a major distress in asphalt pavements. Several test configurations have been introduced to characterize the fracture properties of hot mix (HMA); however, most are considered to be research tools due to the complexity of the test methods or equipment. This dissertation describes the development of the indirect ring tension (IRT) fracture test for HMA, which was designed to be an effective and user-friendly test that could be deployed at the Department of Transportation level. The primary advantages of this innovative and yet practical test include: relatively large fracture surface test zone, simplicity of the specimen geometry, widespread availability of the required test equipment, and ability to test laboratory compacted specimens as well as field cores. Numerical modeling was utilized to calibrate the stress intensity factor formula of the IRT fracture test for various specimen dimensions. The results of this extensive analysis were encapsulated in a single equation. To develop the test procedure, a laboratory study was conducted to determine the optimal test parameters for HMA material. An experimental plan was then developed to evaluate the capability of the test in capturing the variations in the mix properties, asphalt pavement density, asphalt material aging, and test temperature. Five plant-produced HMA mixtures were used in this extensive study, and the results revealed that the IRT fracture test is highly repeatable, and capable of capturing the variations in the fracture properties of HMA. Furthermore, an analytical model was developed based on the viscoelastic properties of HMA to estimate the maximum allowable crack size for the pavements in the experimental study. This analysis indicated that the low-temperature cracking potential of the asphalt mixtures is highly sensitive to the fracture toughness and brittleness of the HMA material. Additionally, the IRT fracture test data seemed to correlate well with the data from the distress survey which was conducted on the pavements after five years of service. The maximum allowable crack size analysis revealed that a significant improvement could be realized in terms of the pavements performance if the HMA were to be compacted to a higher density. Finally, the IRT fracture test data were compared to the results of the disk-shaped compact [DC(t)] test. The results of the two tests showed a strong correlation; however, the IRT test seemed to be more repeatable. KEYWORDS: Asphalt Pavement, Low-Temperature Cracking, Fracture Mechanics, Material Characterization, Laboratory Testing.

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

Choquet, Élodie; Perrin, Marshall D.; Chen, Christine H.

We present the first images of four debris disks observed in scattered light around the young (4–250 Myr old) M dwarfs TWA 7 and TWA 25, the K6 star HD 35650, and the G2 star HD 377. We obtained these images by reprocessing archival Hubble Space Telescope NICMOS coronagraph data with modern post-processing techniques as part of the Archival Legacy Investigation of Circumstellar Environments program. All four disks appear faint and compact compared with other debris disks resolved in scattered light. The disks around TWA 25, HD 35650, and HD 377 appear very inclined, while TWA 7's disk is viewed nearly face-on. The surface brightness of HD 35650's diskmore » is strongly asymmetric. These new detections raise the number of disks resolved in scattered light around M and late-K stars from one (the AU Mic system) to four. This new sample of resolved disks enables comparative studies of heretofore scarce debris disks around low-mass stars relative to solar-type stars.« less

Vulnerability of the Superficial Zone of Immature Articular Cartilage to Compressive Injury

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

Rolauffs, R.; Muehleman, C; Li, J

The zonal composition and functioning of adult articular cartilage causes depth-dependent responses to compressive injury. In immature cartilage, shear and compressive moduli as well as collagen and sulfated glycosaminoglycan (sGAG) content also vary with depth. However, there is little understanding of the depth-dependent damage caused by injury. Since injury to immature knee joints most often causes articular cartilage lesions, this study was undertaken to characterize the zonal dependence of biomechanical, biochemical, and matrix-associated changes caused by compressive injury. Disks from the superficial and deeper zones of bovine calves were biomechanically characterized. Injury to the disks was achieved by applying amore » final strain of 50% compression at 100%/second, followed by biomechanical recharacterization. Tissue compaction upon injury as well as sGAG density, sGAG loss, and biosynthesis were measured. Collagen fiber orientation and matrix damage were assessed using histology, diffraction-enhanced x-ray imaging, and texture analysis. Injured superficial zone disks showed surface disruption, tissue compaction by 20.3 {+-} 4.3% (mean {+-} SEM), and immediate biomechanical impairment that was revealed by a mean {+-} SEM decrease in dynamic stiffness to 7.1 {+-} 3.3% of the value before injury and equilibrium moduli that were below the level of detection. Tissue areas that appeared intact on histology showed clear textural alterations. Injured deeper zone disks showed collagen crimping but remained undamaged and biomechanically intact. Superficial zone disks did not lose sGAG immediately after injury, but lost 17.8 {+-} 1.4% of sGAG after 48 hours; deeper zone disks lost only 2.8 {+-} 0.3% of sGAG content. Biomechanical impairment was associated primarily with structural damage. The soft superficial zone of immature cartilage is vulnerable to compressive injury, causing superficial matrix disruption, extensive compaction, and textural alteration, which results in immediate loss of biomechanical function. In conjunction with delayed superficial sGAG loss, these changes may predispose the articular surface to further softening and tissue damage, thus increasing the risk of development of secondary osteoarthritis.« less

Effect of Reinforcement Architecture on Fracture of Selectively Reinforced Metallic Compact Tension Specimens

NASA Technical Reports Server (NTRS)

Abada, Christopher H.; Farley, Gary L.; Hyer, Michael W.

2006-01-01

A computer-based parametric study of the effect of reinforcement architectures on fracture response of aluminum compact-tension (CT) specimens is performed. Eleven different reinforcement architectures consisting of rectangular and triangular cross-section reinforcements were evaluated. Reinforced specimens produced between 13 and 28 percent higher fracture load than achieved with the non-reinforced case. Reinforcements with blunt leading edges (rectangular reinforcements) exhibited superior performance relative to the triangular reinforcements with sharp leading edges. Relative to the rectangular reinforcements, the most important architectural feature was reinforcement thickness. At failure, the reinforcements carried between 58 and 85 percent of the load applied to the specimen, suggesting that there is considerable load transfer between the base material and the reinforcement.

Rapid solidification and dynamic compaction of Ni-base superalloy powders

NASA Technical Reports Server (NTRS)

Field, R. D.; Hales, S. J.; Powers, W. O.; Fraser, H. L.

1984-01-01

A Ni-base superalloy containing 13Al-9Mo-2Ta (in at. percent) has been characterized in both the rapidly solidified condition and after dynamic compaction. Dynamically compacted specimens were examined in the as-compacted condition and observations related to current theories of interparticle bonding. In addition, the recrystallization behavior of the compacted material at relatively low temperature (about 0.5-0.75 Tm) was investigated.

A model for neutrino emission from nuclear accretion disks

NASA Astrophysics Data System (ADS)

Deaton, Michael

2015-04-01

Compact object mergers involving at least one neutron star can produce short-lived black hole accretion engines. Over tens to hundreds of milliseconds such an engine consumes a disk of hot, nuclear-density fluid, and drives changes to its surrounding environment through luminous emission of neutrinos. The neutrino emission may drive an ultrarelativistic jet, may peel off the disk's outer layers as a wind, may irradiate those winds or other forms of ejecta and thereby change their composition, may change the composition and thermodynamic state of the disk itself, and may oscillate in its flavor content. We present the full spatial-, angular-, and energy-dependence of the neutrino distribution function around a realistic model of a nuclear accretion disk, to inform future explorations of these types of behaviors. Spectral Einstein Code (SpEC).

Lense-Thirring Precession of Accretion Disks and Quasi-Periodic Oscillations in X-Ray Binaries

NASA Astrophysics Data System (ADS)

Markovic, D.; Lamb, F. K.

2003-05-01

It has recently been suggested that gravitomagnetic precession of the inner part of the accretion disk, possibly driven by radiation torques, may be responsible for some of the 20-300 Hz quasi-periodic X-ray brightness oscillations (QPOs) observed in some low-mass binary systems containing accreting neutron stars and black hole candidates. We have explored warping modes of geometrically thin disks in the presence of gravitomagnetic and radiation torques. We have found a family of overdamped, low-frequency gravitomagnetic (LFGM) modes all of which have precession frequencies lower than a certain critical frequency ωcrit, which is 1 Hz for a compact object of solar mass. A radiation warping torque can cause a few of the lowest-frequency LFGM modes to grow with time, but even a strong radiation warping torque has essentially no effect on the LFGM modes with frequencies ≳10-4 Hz. We have also discovered a second family of high-frequency gravitomagnetic (HFGM) modes with precession frequencies that range from ωcrit up to slightly less than the gravitomagnetic precession frequency of a particle at the inner edge of the disk, which is 30 Hz if the disk extends inward to the innermost stable circular orbit around a 2M⊙ compact object with dimensionless angular momentum cJ/GM2 = 0.2. The highest-frequency HFGM modes are very localized spiral corrugations of the inner disk and are weakly damped, with Q values as large as 50. We discuss the implications of our results for the observability of Lense-Thirring precession in X-ray binaries.

Thin disk lasers: history and prospects

NASA Astrophysics Data System (ADS)

Speiser, Jochen

2016-04-01

During the early 1990s, collaboration between the German Aerospace Center and the University of Stuttgart started to work on the Thin Disk concept. The core idea behind the thin disk design is the use of a thin, disk-shaped active medium that is cooled through one of the flat faces of the disk. This ensures a large surface-to-volume ratio and therefore provides very efficient thermal management. Today, the thin disk concept is used in various commercial lasers - ranging from compact, efficient low power systems to multi-kW lasers, including cw lasers and also pulsed (femtosecond to nanosecond) oscillators and amplifiers. The whole development of the Thin Disk laser was and will be accompanied by numerical modeling and optimization of the thermal and thermo-mechanic behavior of the disk and also the heat sink structure, mostly based on finite element models. For further increasing the energy and efficiency of pulsed Thin Disk lasers, the effects of amplified spontaneous emission (ASE) are a core issue. Actual efforts are oriented towards short pulse and ultra-short pulse amplifiers with (multi-)kW average power or Joule-class Thin Disk amplifiers, but also on new designs for cw thin disk MOPA designs.

Resolved H I Observations of Local Analogs to z ∼ 1 Luminous Compact Blue Galaxies: Evidence for Rotation-supported Disks

NASA Astrophysics Data System (ADS)

Rabidoux, Katie; Pisano, D. J.; Garland, C. A.; Guzmán, Rafael; Castander, Francisco J.; Wolfe, Spencer A.

2018-01-01

While bright, blue, compact galaxies are common at z∼ 1, they are relatively rare in the local universe, and their evolutionary paths are uncertain. We have obtained resolved H I observations of nine z∼ 0 luminous compact blue galaxies (LCBGs) using the Giant Metrewave Radio Telescope and Very Large Array in order to measure their kinematic and dynamical properties and better constrain their evolutionary possibilities. We find that the LCBGs in our sample are rotating galaxies that tend to have nearby companions, relatively high central velocity dispersions, and can have disturbed velocity fields. We calculate rotation velocities for each galaxy by measuring half of the velocity gradient along their major axes and correcting for inclination using axis ratios derived from SDSS images of each galaxy. We compare our measurements to those previously made with single dishes and find that single-dish measurements tend to overestimate LCBGs’ rotation velocities and H I masses. We also compare the ratio of LCBGs’ rotation velocities and velocity dispersions to those of other types of galaxies and find that LCBGs are strongly rotationally supported at large radii, similar to other disk galaxies, though within their half-light radii the {V}{rot}/σ values of their H I are comparable to stellar {V}{rot}/σ values of dwarf elliptical galaxies. We find that LCBGs’ disks on average are gravitationally stable, though conditions may be conducive to local gravitational instabilities at the largest radii. Such instabilities could lead to the formation of star-forming gas clumps in the disk, resulting eventually in a small central bulge or bar.

The effect of mechanical stress on electric resistance of nanographite-epoxy composites

NASA Astrophysics Data System (ADS)

Vovchenko, L.; Lazarenko, A.; Matzui, L.; Zhuravkov, A.

2012-03-01

The in-plane electric resistance Ra of composite materials (CMs) thermoexfoliated graphite(TEG)-epoxy resin(ED) under compression along compacting C-axis has been investigated by four-probe method. TEG content was 5-75 wt%. It was shown that specimens prepared by cold pressing are denser and reveal lower values of electric resistivity in comparison with specimens prepared by pouring. It was found that compression of the specimens leads to plastic deformation of specimens (εpl) and essential irreversible decrease of electric resistance during the first cycle of loading (up to 50 MPa), especially for the poured specimens with low density. Within the proposed model the contact resistance Rk between graphite particles in CM has been evaluated and it was shown that it increased with the decrease in TEG content in CM and depends on compacting method of CMs and the dispersity of graphite filler.

All-metal, compact heat exchanger for space cryocoolers

NASA Technical Reports Server (NTRS)

Swift, Walter L.; Valenzuela, Javier; Sixsmith, Herbert

1990-01-01

This report describes the development of a high performance, all metal compact heat exchanger. The device is designed for use in a reverse Brayton cryogenic cooler which provides five watts of refrigeration at 70 K. The heat exchanger consists of a stainless steel tube concentrically assembled within a second stainless steel tube. Approximately 300 pairs of slotted copper disks and matching annular slotted copper plates are positioned along the centerline axis of the concentric tubes. Each of the disks and plates has approximately 1200 precise slots machined by means of a special electric discharge process. Positioning of the disk and plate pairs is accomplished by means of dimples in the surface of the tubes. Mechanical and thermal connections between the tubes and plate/disk pairs are made by solder joints. The heat exchanger assembly is 9 cm in diameter by 50 cm in length and has a mass of 10 kg. The predicted thermal effectiveness is greater than 0.985 at design conditions. Pressure loss at design conditions is less than 5 kPa in both fluid passages. Tests were performed on a subassembly of plates integrally soldered to two end headers. The measured thermal effectiveness of the test article exceeded predicted levels. Pressure losses were negligibly higher than predictions.

Design of a compact disk-like microfluidic platform for enzyme-linked immunosorbent assay.

PubMed

Lai, Siyi; Wang, Shengnian; Luo, Jun; Lee, L James; Yang, Shang-Tian; Madou, Marc J

2004-04-01

This paper presents an integrated microfluidic device on a compact disk (CD) that performs an enzyme-linked immunosorbent assay (ELISA) for rat IgG from a hybridoma cell culture. Centrifugal and capillary forces were used to control the flow sequence of different solutions involved in the ELISA process. The microfluidic device was fabricated on a plastic CD. Each step of the ELISA process was carried out automatically by controlling the rotation speed of the CD. The work on analysis of rat IgG from hybridoma culture showed that the microchip-based ELISA has the same detection range as the conventional method on the 96-well microtiter plate but has advantages such as less reagent consumption and shorter assay time over the conventional method.

Panel 1: A pulsating red giant star and a compact, hot white dwarf star orbit each other.

NASA Technical Reports Server (NTRS)

2002-01-01

Panel 1: A pulsating red giant star and a compact, hot white dwarf star orbit each other. Panel 2: The red giant sheds much of its outer layers in a stellar wind. The white dwarf helps concentrate the wind along a thin equatorial plane. The white dwarf accretes some of this escaping gas forming a disk around the itself. Panel 3: When enough gas accumulates on the white dwarf's surface it explodes as a nova outburst. Most of the hot gas forms a pair of expanding bubbles above and below the equatorial disk. Panel 4: A few thousand years after the bubbles expand into space, the white dwarf goes through another nova outburst and makes another pair of bubbles, which form a distinctive hourglass shape.

A simple physical model for X-ray burst sources

NASA Technical Reports Server (NTRS)

Joss, P. C.; Rappaport, S.

1977-01-01

In connection with information considered by Illarianov and Sunyaev (1975) and van den Heuvel (1975), a simple physical model for an X-ray burst source in the galactic disk is proposed. The model includes an unevolved OB star with a relatively weak stellar wind and a compact object in a close binary system. For some reason, the stellar wind from the OB star is unable to accrete steadily on to the compact object. When the stellar wind is sufficiently weak, the compact object accretes irregularly, leading to X-ray bursts.

Influence of different luting protocols on shear bond strength of computer aided design/computer aided manufacturing resin nanoceramic material to dentin

PubMed Central

Poggio, Claudio; Pigozzo, Marco; Ceci, Matteo; Scribante, Andrea; Beltrami, Riccardo; Chiesa, Marco

2016-01-01

Background: The purpose of this study was to evaluate the influence of three different luting protocols on shear bond strength of computer aided design/computer aided manufacturing (CAD/CAM) resin nanoceramic (RNC) material to dentin. Materials and Methods: In this in vitro study, 30 disks were milled from RNC blocks (Lava Ultimate/3M ESPE) with CAD/CAM technology. The disks were subsequently cemented to the exposed dentin of 30 recently extracted bovine permanent mandibular incisors. The specimens were randomly assigned into 3 groups of 10 teeth each. In Group 1, disks were cemented using a total-etch protocol (Scotchbond™ Universal Etchant phosphoric acid + Scotchbond Universal Adhesive + RelyX™ Ultimate conventional resin cement); in Group 2, disks were cemented using a self-etch protocol (Scotchbond Universal Adhesive + RelyX™ Ultimate conventional resin cement); in Group 3, disks were cemented using a self-adhesive protocol (RelyX™ Unicem 2 Automix self-adhesive resin cement). All cemented specimens were placed in a universal testing machine (Instron Universal Testing Machine 3343) and submitted to a shear bond strength test to check the strength of adhesion between the two substrates, dentin, and RNC disks. Specimens were stressed at a crosshead speed of 1 mm/min. Data were analyzed with analysis of variance and post-hoc Tukey's test at a level of significance of 0.05. Results: Post-hoc Tukey testing showed that the highest shear strength values (P < 0.001) were reported in Group 2. The lowest data (P < 0.001) were recorded in Group 3. Conclusion: Within the limitations of this in vitro study, conventional resin cements (coupled with etch and rinse or self-etch adhesives) showed better shear strength values compared to self-adhesive resin cements. Furthermore, conventional resin cements used together with a self-etch adhesive reported the highest values of adhesion. PMID:27076822

Influence of different luting protocols on shear bond strength of computer aided design/computer aided manufacturing resin nanoceramic material to dentin.

PubMed

Poggio, Claudio; Pigozzo, Marco; Ceci, Matteo; Scribante, Andrea; Beltrami, Riccardo; Chiesa, Marco

2016-01-01

The purpose of this study was to evaluate the influence of three different luting protocols on shear bond strength of computer aided design/computer aided manufacturing (CAD/CAM) resin nanoceramic (RNC) material to dentin. In this in vitro study, 30 disks were milled from RNC blocks (Lava Ultimate/3M ESPE) with CAD/CAM technology. The disks were subsequently cemented to the exposed dentin of 30 recently extracted bovine permanent mandibular incisors. The specimens were randomly assigned into 3 groups of 10 teeth each. In Group 1, disks were cemented using a total-etch protocol (Scotchbond™ Universal Etchant phosphoric acid + Scotchbond Universal Adhesive + RelyX™ Ultimate conventional resin cement); in Group 2, disks were cemented using a self-etch protocol (Scotchbond Universal Adhesive + RelyX™ Ultimate conventional resin cement); in Group 3, disks were cemented using a self-adhesive protocol (RelyX™ Unicem 2 Automix self-adhesive resin cement). All cemented specimens were placed in a universal testing machine (Instron Universal Testing Machine 3343) and submitted to a shear bond strength test to check the strength of adhesion between the two substrates, dentin, and RNC disks. Specimens were stressed at a crosshead speed of 1 mm/min. Data were analyzed with analysis of variance and post-hoc Tukey's test at a level of significance of 0.05. Post-hoc Tukey testing showed that the highest shear strength values (P < 0.001) were reported in Group 2. The lowest data (P < 0.001) were recorded in Group 3. Within the limitations of this in vitro study, conventional resin cements (coupled with etch and rinse or self-etch adhesives) showed better shear strength values compared to self-adhesive resin cements. Furthermore, conventional resin cements used together with a self-etch adhesive reported the highest values of adhesion.

Electron trapping data storage system and applications

NASA Technical Reports Server (NTRS)

Brower, Daniel; Earman, Allen; Chaffin, M. H.

1993-01-01

The advent of digital information storage and retrieval has led to explosive growth in data transmission techniques, data compression alternatives, and the need for high capacity random access data storage. Advances in data storage technologies are limiting the utilization of digitally based systems. New storage technologies will be required which can provide higher data capacities and faster transfer rates in a more compact format. Magnetic disk/tape and current optical data storage technologies do not provide these higher performance requirements for all digital data applications. A new technology developed at the Optex Corporation out-performs all other existing data storage technologies. The Electron Trapping Optical Memory (ETOM) media is capable of storing as much as 14 gigabytes of uncompressed data on a single, double-sided 54 inch disk with a data transfer rate of up to 12 megabits per second. The disk is removable, compact, lightweight, environmentally stable, and robust. Since the Write/Read/Erase (W/R/E) processes are carried out 100 percent photonically, no heating of the recording media is required. Therefore, the storage media suffers no deleterious effects from repeated Write/Read/Erase cycling.

Fracture Behavior of a Stitched Warp-Knit Carbon Fabric Composite

NASA Technical Reports Server (NTRS)

Poe, Clarence C., Jr.; Reeder, James R.; Yuan, F. G.

2001-01-01

Tests were conducted on several types of fracture specimens made from a carbon/epoxy composite. The composite material was stitched prior to introducing epoxy resin. Boeing, used this material to develop a composite wing box for a transport aircraft in the NASA Advanced Composites Transport Program. The specimens included compact, extended compact, and center notched tension specimens. The specimens were cut from panels with three orientations in order to explore the effects of anisotropy. The panels were made with various thicknesses to represent a wing, skin from tip to root. All fractures were not self-similar depending on specimen type and orientation. Unnotched tension specimens were also tested to measure elastic constants and strengths. The normal and shear strains were calculated on fracture planes using a series representation of strain fields for plane anisotropic crack problems. The fracture parameters were determined using a finite element method. Characteristic distances for critical tension and shear strains were calculated for each specimen and a failure criterion based on the interaction of tension and shear strains was proposed.

Major Effects of Nonmetallic Inclusions on the Fatigue Life of Disk Superalloy Demonstrated

NASA Technical Reports Server (NTRS)

Gabb, Timothy P.; Telesman, Jack; Kantzos, Peter T.; Bonacuse, Peter J.; Barrie, Robert L.

2002-01-01

The fatigue properties of modern powder metallurgy disk alloys can vary because of the different steps of materials and component processing and machining. Among these variables, the effects of nonmetallic inclusions introduced during the powder atomization and handling processes have been shown to significantly degrade low-cycle fatigue life. The levels of inclusion contamination have, therefore, been reduced to less than 1 part per million in state-of-the-art nickel disk powder-processing facilities. Yet the large quantities of compressor and turbine disks weighing from 100 to over 1000 lb have enough total volume and surface area for these rare inclusions to still be present and limit fatigue life. The objective of this study was to investigate the effects on fatigue life of these inclusions, as part of the Crack Resistant Disk Materials task within the Ultra Safe Propulsion Project. Inclusions were carefully introduced at elevated levels in a nickel-base disk superalloy, U720, produced using powder metallurgy processing. Multiple strain-controlled fatigue tests were then performed on extracted test specimens at 650 C. Analyses were performed to compare the low-cycle fatigue lives and failure initiation sites as functions of inclusion content and fatigue conditions. Powder of the nickel-base superalloy U720 was atomized in argon at Special Metals Corporation, Inc., using production-scale high-cleanliness powder-processing facilities and handling practices. The powder was then passed through a 270-mesh screen. One portion of this powder was set aside for subsequent consolidation without introduced inclusions. Two other portions of this powder were seeded with alumina inclusions. Small, polycrystalline soft (Type 2) inclusions of about 50 mm diameter were carefully prepared and blended into one powder lot, and larger hard (Type 1) inclusions of about 150 mm mean diameter were introduced into the other seeded portion of powder. All three portions of powder were then sealed in separate containers, hot isostatically pressurized, extruded, forged into subscale disks, and heat treated. Low-cycle-fatigue specimens were then extracted, machined, and tested. Fatigue tests were performed at 650 C in closed-loop servohydraulic testing machines using induction heating and axial extensometers. All tests were continued to failure, and fractographic evaluations were performed on all specimens to determine the crack initiation sites. A large majority of the failures in specimens with introduced inclusions occurred at cracks initiating from inclusions at the specimen surface, as shown for each type of inclusion in the following bar chart. The inclusions significantly reduced fatigue life from unseeded material levels, as shown in the bar chart. These effects were found to depend on the strain range, strain ratio, and inclusion size. Tests at lower strain ranges and higher strain ratios resulted in larger effects of inclusions on life. Inclusion effects on life were thereby maximized in tests at the lowest strain range of 0.6 percent and the most positive strain ratio of 0.5. Under these conditions, small Type 2 inclusions reduced life substantially-- about 20 times, whereas large Type 1 inclusions dramatically reduced life 100 times. These results clearly demonstrate that it is essential to include the effects of inclusions for realistic predictions of disk fatigue life. Important issues, including temperature dependence, crack initiation versus propagation, surface treatments, realistic disk features and machining, and realistic disk spin testing will be addressed to accurately model inclusion effects on disk fatigue life. Fatigue life varied from well over 105 cycles for no inclusions to a little over 103 cycles for 100-micrometer inclusions. A single crack initiating at a surface-connected seeded inclusion caused failure in each case.

The Evolution of the Accretion Disk Around 4U 1820-30 During a Superburst

NASA Technical Reports Server (NTRS)

Ballantyne, D. R.; Strohmayer, T. E.

2004-01-01

Accretion from a disk onto a collapsed, relativistic star - a neutron star or black hole - is the mechanism widely believed to be responsible for the emission from compact X-ray binaries. Because of the extreme spatial resolution required, it is not yet possible to directly observe the evolution or dynamics of the inner parts of the accretion disk where general relativistic effects are dominant. Here, we use the bright X-ray emission from a superburst on the surface of the neutron star 4U 1820-30 as a spotlight to illuminate the disk surface. The X-rays cause iron atoms in the disk t o fluoresce, allowing a determination of the ionization state, covering factor and inner radius of the disk over the course of the burst. The time-resolved spectral fitting shows that the inner region of the disk is disrupted by the burst, possibly being heated into a thicker, more tenuous flow, before recovering its previous form in approximately 1000 s. This marks the first instance that the evolution of the inner regions of an accretion disk has been observed in real-time.

Strength evaluation test of pressureless-sintered silicon nitride at room temperature

NASA Technical Reports Server (NTRS)

Matsusue, K.; Takahara, K.; Hashimoto, R.

1984-01-01

In order to study strength characteristics at room temperature and the strength evaluating method of ceramic materials, the following tests were conducted on pressureless sintered silicon nitride specimens: bending tests, the three tensile tests of rectangular plates, holed plates, and notched plates, and spin tests of centrally holed disks. The relationship between the mean strength of specimens and the effective volume of specimens are examined using Weibull's theory. The effect of surface grinding on the strength of specimens is discussed.

Self-Consistent Thermal Accretion Disk Corona Models for Compact Objects. I: Properties of the Corona and the Spectrum of Escaping Radiation

NASA Technical Reports Server (NTRS)

Dove, James B.; Wilms, Jorn; Begelman, Mitchell C.

1997-01-01

We present the properties of accretion disk corona (ADC) models in which the radiation field, the temperature, and the total opacity of the corona are determined self-consistently. We use a nonlinear Monte Carlo code to perform the calculations. As an example, we discuss models in which the corona is situated above and below a cold accretion disk with a plane-parallel (slab) geometry, similar to the model of Haardt & Maraschi. By Comptonizing the soft radiation emitted by the accretion disk, the corona is responsible for producing the high-energy component of the escaping radiation. Our models include the reprocessing of radiation in the accretion disk. Here the photons either are Compton-reflected or photoabsorbed, giving rise to fluorescent line emission and thermal emission. The self- consistent coronal temperature is determined by balancing heating (due to viscous energy dissipation) with Compton cooling, determined using the fully relativistic, angle-dependent cross sections. The total opacity is found by balancing pair productions with annihilations. We find that, for a disk temperature kT(sub BB) approx. less than 200 eV, these coronae are unable to have a self-consistent temperature higher than approx. 140 keV if the total optical depth is approx. less than 0.2, regardless of the compactness parameter of the corona and the seed opacity. This limitation corresponds to the angle-averaged spectrum of escaping radiation having a photon index approx. greater than 1.8 within the 5-30 keV band. Finally, all models that have reprocessing features also predict a large thermal excess at lower energies. These constraints make explaining the X-ray spectra of persistent black hole candidates with ADC models very problematic.

Characterization of the Temperature Capabilities of Advanced Disk Alloy ME3

NASA Technical Reports Server (NTRS)

Gabb, Timothy P.; Telesman, Jack; Kantzos, Peter T.; OConnor, Kenneth

2002-01-01

The successful development of an advanced powder metallurgy disk alloy, ME3, was initiated in the NASA High Speed Research/Enabling Propulsion Materials (HSR/EPM) Compressor/Turbine Disk program in cooperation with General Electric Engine Company and Pratt & Whitney Aircraft Engines. This alloy was designed using statistical screening and optimization of composition and processing variables to have extended durability at 1200 F in large disks. Disks of this alloy were produced at the conclusion of the program using a realistic scaled-up disk shape and processing to enable demonstration of these properties. The objective of the Ultra-Efficient Engine Technologies disk program was to assess the mechanical properties of these ME3 disks as functions of temperature in order to estimate the maximum temperature capabilities of this advanced alloy. These disks were sectioned, machined into specimens, and extensively tested. Additional sub-scale disks and blanks were processed and selectively tested to explore the effects of several processing variations on mechanical properties. Results indicate the baseline ME3 alloy and process can produce 1300 to 1350 F temperature capabilities, dependent on detailed disk and engine design property requirements.

Compact discs as versatile cost-effective substrates for releasable nanopatterned aluminium films

NASA Astrophysics Data System (ADS)

Barrios, Carlos Angulo; Canalejas-Tejero, Víctor

2015-02-01

We demonstrate that standard polycarbonate compact disk surfaces can provide unique adhesion to Al films that is both strong enough to permit Al film nanopatterning and weak enough to allow easy nanopatterned Al film detachment using Scotch tape. Transferred Al nanohole arrays on Scotch tape exhibit excellent optical and plasmonic performance.We demonstrate that standard polycarbonate compact disk surfaces can provide unique adhesion to Al films that is both strong enough to permit Al film nanopatterning and weak enough to allow easy nanopatterned Al film detachment using Scotch tape. Transferred Al nanohole arrays on Scotch tape exhibit excellent optical and plasmonic performance. Electronic supplementary information (ESI) available: 1. Optical simulations (Fig. SI.1); 2. Optical coupling via an Al NHA on the Scotch tape (Fig. SI.2); 3. Electrostatics-based opto-mechanical cantilever (Fig. SI.3). Video 1. Transfer of the Al film nanostructured with a nanohole array from a polycarbonate CD surface onto a Scotch tape; Video 2. Opto-mechanical electrostatics-based sensor: electrical attraction. Video 3. Opto-mechanical electrostatics-based sensor: electrical repulsion. See DOI: 10.1039/c4nr06271j

Complex Analysis of Diffusion Transport and Microstructure of an Intervertebral Disk.

PubMed

Byvaltsev, V A; Kolesnikov, S I; Belykh, E G; Stepanov, I A; Kalinin, A A; Bardonova, L A; Sudakov, N P; Klimenkov, I V; Nikiforov, S B; Semenov, A V; Perfil'ev, D V; Bespyatykh, I V; Antipina, S L; Giers, M; Prul, M

2017-12-01

We studied the relationship between diffusion transport and morphological and microstructural organization of extracellular matrix of human intervertebral disk. Specimens of the lumbar intervertebral disks without abnormalities were studied ex vivo by diffusion-weighed magnetic resonance imaging, histological and immunohistochemical methods, and electron microscopy. Distribution of the diffusion coefficient in various compartments of the intervertebral disk was studied. Significant correlations between diffusion coefficient and cell density in the nucleus pulposus, posterior aspects of annulus fibrosus, and endplate at the level of the posterior annulus fibrosus were detected for each disk. In disks with nucleus pulposus diffusion coefficient below 15×10 -4 mm 2 /sec, collagens X and XI were detected apart from aggrecan and collagens I and II. The results supplement the concept on the relationship between the microstructure and cell composition of various compartments of the intervertebral disk and parameters of nutrient transport.

Heat transfer in a compact tubular heat exchanger with helium gas at 3.5 MPa

NASA Technical Reports Server (NTRS)

Olson, Douglas A.; Glover, Michael P.

1990-01-01

A compact heat exchanger was constructed consisting of circular tubes in parallel brazed to a grooved base plate. This tube specimen heat exchanger was tested in an apparatus which radiatively heated the specimen on one side at a heat flux of up to 54 W/sq cm, and cooled the specimen with helium gas at 3.5 MPa and Reynolds numbers of 3000 to 35,000. The measured friction factor of the tube specimen was lower than that of a circular tube with fully developed turbulent flow, although the uncertainty was high due to entrance and exit losses. The measured Nusselt number, when modified to account for differences in fluid properties between the wall and the cooling fluid, agreed with past correlations for fully developed turbulent flow in circular tubes.

Comparison between instrumented precracked Charpy and compact specimen tests of carbon steels

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

Nanstad, R.K.

1980-01-01

The General Atomic Company High Temperature Gas-Cooled Reactor (HTGR) is housed within a prestressed concrete reactor vessel (PCRV). Various carbon steel structural members serve as closures at penetrations in the vessel. A program of testing and evaluation is underway to determine the need for reference fracture toughness (K/sub IR/) and indexing procedures for these materials as described in Appendix G to Section III, ASME Code for light water reactor steels. The materials of interest are carbon steel forgings (SA508, Class 1) and plates (SA537, Classes 1 and 2) as well as weldments of these steels. The fracture toughness behavior ismore » characterized with instrumented precracked Charpy V-votch specimens (PCVN) - slow-bend and dynamic - and compact specimens (10-mm and 25-mm thicknesses) using both linear elastic (ASTM E399) and elastic-plastic (equivalent Energy and J-Integral) analytical procedures. For the dynamic PCVN tests, force-time traces are analyzed according to the procedures of the Pressure Vessel Research Council (PVRC)/Metal Properties Council (MPC). Testing and analytical procedures are discussed and PCVN results are compared to those obtained with compact specimens.« less

Mode-locked thin-disk lasers and their potential application for high-power terahertz generation

NASA Astrophysics Data System (ADS)

Saraceno, Clara J.

2018-04-01

The progress achieved in the last few decades in the performance of ultrafast laser systems with high average power has been tremendous, and continues to provide momentum to new exciting applications, both in scientific research and technology. Among the various technological advances that have shaped this progress, mode-locked thin-disk oscillators have attracted significant attention as a unique technology capable of providing ultrashort pulses with high energy (tens to hundreds of microjoules) and at very high repetition rates (in the megahertz regime) from a single table-top oscillator. This technology opens the door to compact high repetition rate ultrafast sources spanning the entire electromagnetic spectrum from the XUV to the terahertz regime, opening various new application fields. In this article, we focus on their unexplored potential as compact driving sources for high average power terahertz generation.

Enabling Large Superalloy Parts Using Compact Coprecipitation of γ' and γ''

NASA Astrophysics Data System (ADS)

Detor, Andrew J.; DiDomizio, Richard; Sharghi-Moshtaghin, Reza; Zhou, Ning; Shi, Rongpei; Wang, Yunzhi; McAllister, Donald P.; Mills, Michael J.

2018-03-01

Next-generation gas turbines will require disk materials capable of operating at 923 K (650 °C) and above to achieve efficiencies well beyond today's 62 pct benchmark. This temperature requirement marks a critical turning point in materials selection. Current turbine disk alloys, such as 706 and 718, are limited by the stability of their major strengthening phase, γ'', which coarsens rapidly beyond 923 K (650 °C) resulting in significant degradation in properties. More capable γ' strengthened superalloys, such as those used in jet engine disks, are also limited due to the sheer size of gas turbine hardware; the γ' phase overages during the slow cooling rates inherent in processing thick-section parts. In the present work, we address this fundamental gap in available superalloy materials. Through careful control of Al, Ti, and Nb levels, we show that fine (<100 nm) γ' and compact γ'/γ'' coprecipitate structures can be formed even under extremely slow cooling rates from high temperature. The presence of Ti is shown to have a dominant effect on phase formation, dictating whether γ', γ'/γ'' coprecipitates, or other less desirable acicular phases form on cooling. Sensitivity to cooling rate and aging heat treatment is also explored. A custom phase field model along with commercial precipitation kinetics software is used to better understand the phase evolution and stability of compact coprecipitates. The alloying strategies discussed here enable a new class of superalloys suitable for applications requiring large parts operating at high temperature.

Generation of dynamo magnetic fields in thin Keplerian disks

NASA Technical Reports Server (NTRS)

Stepinski, T. F.; Levy, E. H.

1990-01-01

The combined action of nonuniform rotation and helical convection in protoplanetary disks, in the Galaxy, or in accretion disks surrounding black holes and other compact objects, enables an alpha-omega dynamo to generate a large-scale magnetic field. In this paper, the properties of such magnetic fields are investigated using a two-dimensional, partially numerical method. The structures of the lowest-order steady state and oscillatory modes are calculated for two kinds of external boundary conditions. A quadruple, steady state, highly localized mode is the most easily excited for low values of the dynamo number. The results indicate that, except under special conditions, disk dynamo modes tend to consist of relatively localized rings structures. For large values of the dynamo number, the magnetic field consists of a number of quasi-independent, spatially localized modes generated in various concentric rings filling the disk inward of a dynamo generation 'front'.

Self-gravitating axially symmetric disks in general-relativistic rotation

NASA Astrophysics Data System (ADS)

Karkowski, Janusz; Kulczycki, Wojciech; Mach, Patryk; Malec, Edward; Odrzywołek, Andrzej; Piróg, Michał

2018-05-01

We integrate numerically axially symmetric stationary Einstein equations describing self-gravitating disks around spinless black holes. The numerical scheme is based on a method developed by Shibata, but contains important new ingredients. We derive a new general-relativistic Keplerian rotation law for self-gravitating disks around spinning black holes. Former results concerning rotation around spinless black holes emerge in the limit of a vanishing spin parameter. These rotation curves might be used for the description of rotating stars, after appropriate modification around the symmetry axis. They can be applied to the description of compact torus-black hole configurations, including active galactic nuclei or products of coalescences of two neutron stars.

X-ray imaging of water motion during capillary imbibition: A study on how compaction bands impact fluid flow in Bentheim sandstone

NASA Astrophysics Data System (ADS)

Pons, A.; David, C.; Fortin, J.; Stanchits, S.; MenéNdez, B.; Mengus, J. M.

2011-03-01

To investigate the effect of compaction bands (CB) on fluid flow, capillary imbibition experiments were performed on Bentheim sandstone specimens (initial porosity ˜22.7%) using an industrial X-ray scanner. We used a three-step procedure combining (1) X-ray imaging of capillary rise in intact Bentheim sandstone, (2) formation of compaction band under triaxial tests, at 185 MPa effective pressure, with acoustic emissions (AE) recording for localization of the induced damage, and (3) again X-ray imaging of capillary rise in the damaged specimens after the unloading. The experiments were performed on intact cylindrical specimens, 5 cm in diameter and 10.5 cm in length, cored in different orientations (parallel or perpendicular to the bedding). Analysis of the images obtained at different stages of the capillary imbibition shows that the presence of CB slows down the imbibition and disturbs the geometry of water flow. In addition, we show that the CB geometry derived from X-ray density maps analysis is well correlated with the AE location obtained during triaxial test. The analysis of the water front kinetics was conducted using a simple theoretical model, which allowed us to confirm that compaction bands act as a barrier for fluid flow, not fully impermeable though. We estimate a contrast of permeability of a factor of ˜3 between the host rock and the compaction bands. This estimation of the permeability inside the compaction band is consistent with estimations done in similar sandstones from field studies but differs by 1 order of magnitude from estimations from previous laboratory measurements.

High-Nickel Iron-Sulfides in Anhydrous, Gems-Rich CP IDPs

NASA Technical Reports Server (NTRS)

FLynn, G. J.; Keller, L. P.; Wirick, S.; Hu, W.; Li, L.; Yan, H.; Huang, X.; Nazaretski, E.; Lauer, K.; Chu, Y. S.

2016-01-01

Chondritic porous interplanetary dust particles (CP IDPs) that were not severly heated during atmospheric deceleration are the best preserved samples of the solids that condensed from the Solar protoplanetary disk, as well as pre-Solar grains thatr survived incorporation into the disk, currently available for laboratory analysis [1]. These CP IDPs never experienced the aqueous and/or thermal processing, gravitational compaction, and shock effects that overprinted the record of Solar nebula processes in meteorites.

Evaluation of Stress Corrosion Cracking Susceptibility Using Fracture Mechanics Techniques, Part 1. [environmental tests of aluminum alloys, stainless steels, and titanium alloys

NASA Technical Reports Server (NTRS)

Sprowls, D. O.; Shumaker, M. B.; Walsh, J. D.; Coursen, J. W.

1973-01-01

Stress corrosion cracking (SSC) tests were performed on 13 aluminum alloys, 13 precipitation hardening stainless steels, and two titanium 6Al-4V alloy forgings to compare fracture mechanics techniques with the conventional smooth specimen procedures. Commercially fabricated plate and rolled or forged bars 2 to 2.5-in. thick were tested. Exposures were conducted outdoors in a seacoast atmosphere and in an inland industrial atmosphere to relate the accelerated tests with service type environments. With the fracture mechanics technique tests were made chiefly on bolt loaded fatigue precracked compact tension specimens of the type used for plane-strain fracture toughness tests. Additional tests of the aluminum alloy were performed on ring loaded compact tension specimens and on bolt loaded double cantilever beams. For the smooth specimen procedure 0.125-in. dia. tensile specimens were loaded axially in constant deformation type frames. For both aluminum and steel alloys comparative SCC growth rates obtained from tests of precracked specimens provide an additional useful characterization of the SCC behavior of an alloy.

Mixing and Compaction Temperatures for Hot Mix Asphalt Concrete

DOT National Transportation Integrated Search

2000-01-01

According to Superpave mixture design, gyratory specimens are mixed and compacted at equiviscous binder temperatures corresponding to viscosities of 0.17 and 0.28 Pa's, respectively. These were the values previously used in the Marshal mix design met...

Measurement of Circumstellar Disk Sizes in the Upper Scorpius OB Association with ALMA

NASA Astrophysics Data System (ADS)

Barenfeld, Scott A.; Carpenter, John M.; Sargent, Anneila I.; Isella, Andrea; Ricci, Luca

2017-12-01

We present detailed modeling of the spatial distributions of gas and dust in 57 circumstellar disks in the Upper Scorpius OB Association observed with ALMA at submillimeter wavelengths. We fit power-law models to the dust surface density and CO J = 3–2 surface brightness to measure the radial extent of dust and gas in these disks. We found that these disks are extremely compact: the 25 highest signal-to-noise disks have a median dust outer radius of 21 au, assuming an {R}-1 dust surface density profile. Our lack of CO detections in the majority of our sample is consistent with these small disk sizes assuming the dust and CO share the same spatial distribution. Of seven disks in our sample with well-constrained dust and CO radii, four appear to be more extended in CO, although this may simply be due to the higher optical depth of the CO. Comparison of the Upper Sco results with recent analyses of disks in Taurus, Ophiuchus, and Lupus suggests that the dust disks in Upper Sco may be approximately three times smaller in size than their younger counterparts, although we caution that a more uniform analysis of the data across all regions is needed. We discuss the implications of these results for disk evolution.

High-strain rate tensile characterization of graphite platelet reinforced vinyl ester based nanocomposites using split-Hopkinson pressure bar

NASA Astrophysics Data System (ADS)

Pramanik, Brahmananda

The dynamic response of exfoliated graphite nanoplatelet (xGnP) reinforced and carboxyl terminated butadiene nitrile (CTBN) toughened vinyl ester based nanocomposites are characterized under both dynamic tensile and compressive loading. Dynamic direct tensile tests are performed applying the reverse impact Split Hopkinson Pressure Bar (SHPB) technique. The specimen geometry for tensile test is parametrically optimized by Finite Element Analysis (FEA) using ANSYS Mechanical APDLRTM. Uniform stress distribution within the specimen gage length has been verified using high-speed digital photography. The on-specimen strain gage installation is substituted by a non-contact Laser Occlusion Expansion Gage (LOEG) technique for infinitesimal dynamic tensile strain measurements. Due to very low transmitted pulse signal, an alternative approach based on incident pulse is applied for obtaining the stress-time history. Indirect tensile tests are also performed combining the conventional SHPB technique with Brazilian disk test method for evaluating cylindrical disk specimens. The cylindrical disk specimen is held snugly in between two concave end fixtures attached to the incident and transmission bars. Indirect tensile stress is estimated from the SHPB pulses, and diametrical transverse tensile strain is measured using LOEG. Failure diagnosis using high-speed digital photography validates the viability of utilizing this indirect test method for characterizing the tensile properties of the candidate vinyl ester based nanocomposite system. Also, quasi-static indirect tensile response agrees with previous investigations conducted using the traditional dog-bone specimen in quasi-static direct tensile tests. Investigation of both quasi-static and dynamic indirect tensile test responses show the strain rate effect on the tensile strength and energy absorbing capacity of the candidate materials. Finally, the conventional compressive SHPB tests are performed. It is observed that both strength and energy absorbing capacity of these candidate material systems are distinctively less under dynamic tension than under compressive loading. Nano-reinforcement appears to marginally improve these properties for pure vinyl ester under dynamic tension, although it is found to be detrimental under dynamic compression.

Fracture toughness measurements of three titanium alloy extrusions

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

DeSisto, T.S.

1973-07-01

Plane strain static K/sub Ic/ and dynamic Kid measurements were obtained on 3-in. dia. titanium alloy extrusions which received a 5.9: 1 reduction followed by air cooling. The alloys investigated were Ti-6Al--6V--2Sn, Ti--8Mo-- 8V--2Fe--3Al, and Ti-- 11.5Mo-6Zr-4.5Sn (Beta III). Compact tension specimens were used to obtain K/sub Ic/ measurements and precracked standard Charpy V- notched specimens were used to obtain Kid measurements. The highest K/sub Ic/ and K /sub Id/ values were obtained from the Beta III extrusion while the lowest K/sub Ic/ and K/sub Id/ values were obtained for the Ti-8Mo--8V--2Fe -- 3Al extrusion. Good agreement was found tomore » exist between K/sub Ic/ values obtained from precracked Charpy V-notch specimens and compact tension specimens. (auth)« less

Contribution of collagen fibers to the compressive stiffness of cartilaginous tissues.

PubMed

Römgens, Anne M; van Donkelaar, Corrinus C; Ito, Keita

2013-11-01

Cartilaginous tissues such as the intervertebral disk are predominantly loaded under compression. Yet, they contain abundant collagen fibers, which are generally assumed to contribute to tensile loading only. Fiber tension is thought to originate from swelling of the proteoglycan-rich nucleus. However, in aged or degenerate disk, proteoglycans are depleted, whereas collagen content changes little. The question then rises to which extend the collagen may contribute to the compressive stiffness of the tissue. We hypothesized that this contribution is significant at high strain magnitudes and that the effect depends on fiber orientation. In addition, we aimed to determine the compression of the matrix. Bovine inner and outer annulus fibrosus specimens were subjected to incremental confined compression tests up to 60 % strain in radial and circumferential direction. The compressive aggregate modulus was determined per 10 % strain increment. The biochemical composition of the compressed specimens and uncompressed adjacent tissue was determined to compute solid matrix compression. The stiffness of all specimens increased nonlinearly with strain. The collagen-rich outer annulus was significantly stiffer than the inner annulus above 20 % compressive strain. Orientation influenced the modulus in the collagen-rich outer annulus. Finally, it was shown that the solid matrix was significantly compressed above 30 % strain. Therefore, we concluded that collagen fibers significantly contribute to the compressive stiffness of the intervertebral disk at high strains. This is valuable for understanding the compressive behavior of collagen-reinforced tissues in general, and may be particularly relevant for aging or degenerate disks, which become more fibrous and less hydrated.

Sintering behavior of U 80 at.%Zr powder compacts in a vacuum environment

NASA Astrophysics Data System (ADS)

Kim, Tae-Kyu; Lee, Chong-Tak; Sohn, Dong-Seong

2008-01-01

Sintering behavior of U-80 at.%Zr powder compacts in a temperature range from 1100 to 1500 °C in a vacuum of 1 × 10 -4 Pa was evaluated. The sintered density depended more on the sintering temperature than on the sintering time. The sintered specimens consisted of the δ-UZr 2 matrix with acicular α-Zr precipitates, but it still had un-reacted zirconium when the sintering temperature was 1100 °C. The uranium depletion near the surface of the specimens sintered at temperatures above 1300 °C was detected. Massive Zr(O) grains in the sintered specimen were found, and their formation was restrained when the cooling rate from the sintering temperature was increased.

The Dugdale model for the compact specimen

NASA Technical Reports Server (NTRS)

Mall, S.; Newman, J. C., Jr.

1983-01-01

Plastic zone size and crack tip opening displacement (CTOD) equations were developed. Boundary collocation analyses were used to analyze the compact specimen subjected to various loading conditions (pin loads, concentrated forces, and uniform pressure acting on the crack surface). Stress intensity factor and crack surface displacement equations for some of these loadings were developed and used to obtain the Dugdale model. The results from the equations for plastic zone size and CTOD agreed well with numerical values calculated by Terada for crack length to width ratios greater than 0.4.

Accretion Disk Spectra of the Ultra-luminous X-ray Sources in Nearby Spiral Galaxies and Galactic Superluminal Jet Sources

NASA Technical Reports Server (NTRS)

White, Nicholas E. (Technical Monitor); Ebisawa, Ken; Zycki, Piotr; Kubota, Aya; Mizuno, Tsunefumi; Watarai, Ken-ya

2003-01-01

Ultra-luminous Compact X-ray Sources (ULXs) in nearby spiral galaxies and Galactic superluminal jet sources share the common spectral characteristic that they have unusually high disk temperatures which cannot be explained in the framework of the standard optically thick accretion disk in the Schwarzschild metric. On the other hand, the standard accretion disk around the Kerr black hole might explain the observed high disk temperature, as the inner radius of the Kerr disk gets smaller and the disk temperature can be consequently higher. However, we point out that the observable Kerr disk spectra becomes significantly harder than Schwarzschild disk spectra only when the disk is highly inclined. This is because the emission from the innermost part of the accretion disk is Doppler-boosted for an edge-on Kerr disk, while hardly seen for a face-on disk. The Galactic superluminal jet sources are known to be highly inclined systems, thus their energy spectra may be explained with the standard Kerr disk with known black hole masses. For ULXs, on the other hand, the standard Kerr disk model seems implausible, since it is highly unlikely that their accretion disks are preferentially inclined, and, if edge-on Kerr disk model is applied, the black hole mass becomes unreasonably large (greater than or approximately equal to 300 Solar Mass). Instead, the slim disk (advection dominated optically thick disk) model is likely to explain the observed super- Eddington luminosities, hard energy spectra, and spectral variations of ULXs. We suggest that ULXs are accreting black holes with a few tens of solar mass, which is not unexpected from the standard stellar evolution scenario, and their X-ray emission is from the slim disk shining at super-Eddington luminosities.

A High-velocity Cloud Impact Forming a Supershell in the Milky Way

NASA Astrophysics Data System (ADS)

Park, Geumsook; Koo, Bon-Chul; Kang, Ji-hyun; Gibson, Steven J.; Peek, J. E. G.; Douglas, Kevin A.; Korpela, Eric J.; Heiles, Carl E.

2016-08-01

Neutral atomic hydrogen (H I) gas in interstellar space is largely organized into filaments, loops, and shells, the most prominent of which are “supershells.” These gigantic structures, which require ≳ 3× {10}52 erg to form, are generally thought to be produced by either the explosion of multiple supernovae (SNe) in OB associations or, alternatively, by the impact of high-velocity clouds (HVCs) falling into the Galactic disk. Here, we report the detection of a kiloparsec (kpc)-size supershell in the outskirts of the Milky Way with the compact HVC 040 + 01-282 (hereafter, CHVC040) at its geometrical center using the “Inner-Galaxy Arecibo L-band Feed Array” H I 21 cm survey data. The morphological and physical properties of both objects suggest that CHVC040, which is either a fragment of a nearby disrupted galaxy or a cloud that originated from an intergalactic accreting flow, collided with the disk ˜5 Myr ago to form the supershell. Our results show that some compact HVCs can survive their trip through the Galactic halo and inject energy and momentum into the Milky Way disk.

Dual Microstructure Heat Treatment of a Nickel-Base Disk Alloy

NASA Technical Reports Server (NTRS)

Gayda, John

2001-01-01

Existing Dual Microstructure Heat Treat (DMHT) technology was successfully applied to Alloy 10, a high strength, nickel-base disk alloy, to produce a disk with a fine grain bore and coarse grain rim. Specimens were extracted from the DMHT disk and tested in tension, creep, fatigue, and crack growth using conditions pertinent to disk applications. These data were then compared with data from "traditional" subsolvus and supersolvus heat treatments for Alloy 10. The results showed the DMHT disk to have a high strength, fatigue resistant bore comparable to that of subsolvus Alloy 10. Further, creep resistance of the DMHT rim was comparable to that of supersolvus Alloy 10. Crack growth resistance in the DMHT rim, while better than that for subsolvus, was inferior to that of supersolvus Alloy 10. The slow cool at the end of the DMHT conversion and/or the subsolvus resolution step are thought to be responsible for degrading rim DMHT crack growth resistance.

A simple and compact mechanical velocity selector of use to analyze/select molecular alignment in supersonic seeded beams

NASA Astrophysics Data System (ADS)

Pirani, F.; Cappelletti, D.; Vecchiocattivi, F.; Vattuone, L.; Gerbi, A.; Rocca, M.; Valbusa, U.

2004-02-01

A light and compact mechanical velocity selector, of novel design, for applications in supersonic molecular-beam studies has been developed. It represents a simplified version of the traditional, 50 year old, slotted disks velocity selector. Taking advantage of new materials and improved machining techniques, the new version has been realized with only two rotating slotted disks, driven by an electrical motor with adjustable frequency of rotation, and thus has a much smaller weight and size with respect to the original design, which may allow easier implementation in most of the available molecular-beam apparatuses. This new type of selector, which maintains a sufficiently high velocity resolution, has been developed for sampling molecules with different degrees of rotational alignment, like those emerging from a seeded supersonic expansion. This sampling is the crucial step to realize new molecular-beam experiments to study the effect of molecular alignment in collisional processes.

A (12)CO J = 2-1 map of the disk of Centaurus A: Evidence for large scale heating in the dust lane

NASA Technical Reports Server (NTRS)

Wild, W.; Cameron, M.; Eckart, A.; Genzel, R.; Rothermel, H.; Rydbeck, G.; Wiklind, T.

1993-01-01

Centaurus A (NGC 5128) is a nearby (3 Mpc) elliptical galaxy with a prominent dust lane, extensive radio lobes, and a compact radio continuum source, suggestive of nuclear activity. As a consequence of its peculiar morphology, this merger candidate has been the subject of much attention, particularly at optical wavelengths. Unfortunately the high and patchy extinction in the disk, aggravated by the warped structure of the dust lane, has severely hindered investigations into the properties of the interstellar medium, particularly with regard to the extent of star formation. Here we present a map of the (12)CO J = 2-1 line throughout the dust lane which, when combined with a previously measured (12)CO J = 1-0 map and data on molecular absorption lines observed against the compact non-thermal continuum source, offers insight into the excitation conditions of the molecular gas.

Fatigue failure of dentin-composite disks subjected to cyclic diametral compression

PubMed Central

Li, Yuping; Carrera, Carola; Chen, Ruoqiong; Li, Jianying; Chen, Yungchung; Lenton, Patricia; Rudney, Joel. D.; Jones, Robert S.; Aparicio, Conrado; Fok, Alex

2015-01-01

Objective Our aim was to establish the relationship between cyclic loading and fatigue life of the dentin-composite interface using the newly developed disk in diametral compression tests. The results were then used to estimate the fatigue life of restored teeth under occlusal loading. Methods Disk specimens (5mm dia. × 2mm thick) were prepared using bovine incisors and restored with either a methacrylate-based composite Z100™ with Adper Single Bond Plus (Z100) or silorane-based composite Filtek ™ LS with LS System adhesive (LS). The dentin-composite disks were tested under cyclic diametral compression to determine the number of cycles to failure (Nf) at three load levels (n = 3 per group). Finite element analysis (FEA) was used to calculate the interfacial stresses (σ) within the specimen, to establish the σ vs. Nf curves, and those within a restored tooth under normal chewing forces (15N maximum). These were then used to estimate the lifetime of the restored tooth for the two restorative systems. Results The disks restored with LS had a higher fatigue resistance than those restored with Z100. The maximum interfacial stress in the restored tooth determined by FEA was ∼0.5MPa. Based on the estimate of 300,000 cycles of chewing per year, the predicted lifetime under occlusal loading for teeth restored with LS and Z100 was 33 and 10 years, respectively. Significance The disk in cyclic diametral compression has been used successfully to provide fatigue data which allows the lifetime of composite-restored teeth under occlusal loading to be predicted using numerical simulation. PMID:25958269

Apparatus for tensile testing plate-type ceramic specimens

DOEpatents

Liu, Kenneth C.

1993-01-01

Apparatus for tensile testing plate-type ceramic specimens having dogbone- or T-shaped end sections without introducing bending stresses in the specimens during the application of a dynamic tensile loading on the specimens is described. A pair of elongated pull rods disposed in a side-by-side relationship are used to grip the shoulders on each T-shaped end section. The pull rods are pivotally attached to a piston-displaceable, disk-shaped member so as to be longitudinally movable with respect to one another effecting the self-alignment thereof with the shoulders on the T-shaped end sections of the specimen to compensate for shoulders being located in different longitudinal positions.

In vitro antibacterial activity of adhesive systems on Streptococcus mutans.

PubMed

Paradella, Thaís Cachuté; Koga-Ito, Cristiane Yumi; Jorge, Antonio Olavo Cardoso

2009-04-01

To evaluate the antibacterial activity of three adhesive systems -- Prime & Bond 2.1 (PB), Clearfil SE Bond (CS) and One Up Bond F (OU) -- on Streptococcus mutans in vitro. Adherence and agar disk-diffusion tests were performed. For the adherence testing, 40 human enamel specimens (4 mm2) were sterilized and the adhesive sytems were applied (n = 10). The control group did not receive the application of any adhesive system. Specimens were immersed in brain heart infusion broth (BHI) inoculated with S. mutans standardized suspension (10(6) cells/ml) for 48 h at 37 degrees C and 5% CO2. The number of S. mutans cells adhered to each specimen was evaluated by the plating method on BHI agar. For agar disk-diffusion testing, adhesive disks and disks soaked in distilled water (negative control) or 0.2% chlorexidine (positive control) were incubated with S. mutans for 48 h. The diameters of the zones of bacterial inhibition were measured. Adherence data were transformed in logarithms of base 10 (log10). Data were submitted to Kruskal-Wallis and Student-Neuman-Keuls tests at the 5% level of significance. The results of the adherence test showed that One Up Bond F (OU) and Clearfil SE Bond (CS) did not differ significantly from one another, but allowed significantly less adherence than Prime & Bond 2.1 (PB) and control [mean log10 (standard deviation) values: PB 6.10 (0.19); CS primer 4.55 (0.98); OU 4.65 (0.54); control group 6.34 (0.27)]. The disk-diffusion test showed no significant difference between OU (diameter in mm: 3.02 +/- 0.13) and CS (3.0 +/- 0.12), but both were significantly more effective in inhibiting bacterial growth than PB (1.0 +/- 0.10). The self-etching systems Clearfil SE Bond and One Up Bond F presented a greater inhibitory effect against S. mutans, also in terms of adherence, than did the conventional system, Prime & Bond 2.1.

Accretion Disk Outflows from Compact Object Mergers

NASA Astrophysics Data System (ADS)

Metzger, Brian

Nuclear reactions play a key role in the accretion disks and outflows associated with the merger of binary compact objects and the central engines of gamma-ray bursts and supernovae. The proposed research program will investigate the impact of nucleosynthesis on these events and their observable signatures by means of analytic calculations and numerical simulations. One focus of this research is rapid accretion following the tidal disruption of a white dwarf (WD) by a neutron star (NS) or black hole (BH) binary companion. Tidal disruption shreds the WD into a massive torus composed of C, O, and/or He, which undergoes nuclear reactions and burns to increasingly heavier elements as it flows to smaller radii towards the central compact object. The nuclear energy so released is comparable to that released gravitationally, suggesting that burning could drastically alter the structure and stability of the accretion flow. Axisymmetric hydrodynamic simulations of the evolution of the torus including nuclear burning will be performed to explore issues such as the mass budget of the flow (accretion vs. outflows) and its thermal stability (steady burning and accretion vs. runaway explosion). The mass, velocity, and composition of outflows from the disk will be used in separate radiative transfer calculations to predict the lightcurves and spectra of the 56Ni-decay powered optical transients from WD-NS/WD-BH mergers. The possible connection of such events to recently discovered classes of sub-luminous Type I supernovae will be assessed. The coalescence of NS-NS/NS-BH binaries also results in the formation of a massive torus surrounding a central compact object. Three-dimensional magnetohydrodynamic simulations of the long-term evolution of such accretion disks will be performed, which for the first time follow the effects of weak interactions and the nuclear energy released by Helium recombination. The nucleosynthetic yield of disk outflows will be calculated using a detailed nuclear reaction network along characteristic Lagrangian trajectories. Results of these calculations will be used to (1) reassess NS-NS/NS-BH mergers as an astrophysical source of heavy r-process nuclei; and (2) calculate the light curves of the optical transients (`kilonovae') powered by the radioactive decay. Separate work will assess the effects that neutrino irradiation from a long-lived neutron star remnant has on the electron fraction of the disk outflows. The strong contrast between the opacities of proton- and neutron-rich matter imply that the presence and lifetime of such a remnant could be imprinted on the kilonova emission. Our investigation sheds light on the central engines of GRBs and other high-energy transients and hence is relevant to NASA's Swift, MAXI, and Fermi missions. Our results will also impact the interpretation of future observations of supernovae and their galactic environments with the Hubble Space Telescope (HST). Our results will also impact follow-up observations of kilonovae, maximizing the impact of HST to constrain the key open questions such as the progenitors of gamma-ray bursts and the origin of r-process nuclei.

p-Process Nucleosynthesis inside Supernova-driven Supercritical Accretion Disks

NASA Astrophysics Data System (ADS)

Fujimoto, Shin-ichirou; Hashimoto, Masa-aki; Koike, Osamu; Arai, Kenzo; Matsuba, Ryuichi

2003-03-01

We investigate p-process nucleosynthesis in a supercritical accretion disk around a compact object of 1.4 Msolar, using the self-similar solution of an optically thick advection-dominated flow. Supercritical accretion is expected to occur in a supernova with fallback material accreting onto a newborn compact object. It is found that an appreciable number of p-nuclei are synthesized via the p-process in supernova-driven supercritical accretion disks (SSADs) when the accretion rate m=Mc2/(16LEdd)>105, where LEdd is the Eddington luminosity. Abundance profiles of p-nuclei ejected from SSADs have features similar to those of the oxygen/neon layers in Type II supernovae when the abundance of the fallback gas far from the compact object is that of the oxygen/neon layers in the progenitor. The overall abundance profile is in agreement with that of the solar system. Some p-nuclei, such as Mo, Ru, Sn, and La, are underproduced in the SSADs as in Type II supernovae. If the fallback gas is mixed with a small fraction of protons through Rayleigh-Taylor instability during the explosion, significant amounts of 92Mo are produced inside the SSADs. Isotopes 96Ru and 138La are also produced when the fallback gas contains abundant protons, although the overall abundance profile of p-nuclei is rather different from that of the solar system. The p-process nucleosynthesis in SSADs contributes to the chemical evolution of p-nuclei, in particular 92Mo, if several percent of the fallback matter are ejected via jets and/or winds.

Kepler-444 Planetary System Artist Concept

NASA Image and Video Library

2015-01-28

The tightly packed system, named Kepler-444, is home to five small planets in very compact orbits. The planets were detected from the dimming that occurs when they transit the disk of their parent star, as shown in this artist conception.

Effect of crack curvature on stress intensity factors for ASTM standard compact tension specimens

NASA Technical Reports Server (NTRS)

Alam, J.; Mendelson, A.

1983-01-01

The stress intensity factors (SIF) are calculated using the method of lines for the compact tension specimen in tensile and shear loading for curved crack fronts. For the purely elastic case, it was found that as the crack front curvature increases, the SIF value at the center of the specimen decreases while increasing at the surface. For the higher values of crack front curvatures, the maximum value of the SIF occurs at an interior point located adjacent to the surface. A thickness average SIF was computed for parabolically applied shear loading. These results were used to assess the requirements of ASTM standards E399-71 and E399-81 on the shape of crack fronts. The SIF is assumed to reflect the average stress environment near the crack edge.

Apparatus for Screening Multiple Oxygen-Reduction Catalysts

NASA Technical Reports Server (NTRS)

Whitacre, Jay; Narayanan, Sekharipuram

2009-01-01

An apparatus that includes an array of multiple electrodes has been invented as a means of simultaneously testing multiple materials for their utility as oxygen-reduction catalysts in fuel cells. The apparatus ensures comparability of test results by exposing all the catalyst-material specimens to the same electrolytic test solution at the same potential. Heretofore, it has been possible to test only one specimen at a time, using a precise rotating disk electrode that provides a controlled flux of solution to the surface of the specimen.

Radial Angular Momentum Transfer and Magnetic Barrier for Short-type Gamma-Ray-burst Central Engine Activity

NASA Astrophysics Data System (ADS)

Liu, Tong; Liang, En-Wei; Gu, Wei-Min; Hou, Shu-Jin; Lei, Wei-Hua; Lin, Lin; Dai, Zi-Gao; Zhang, Shuang-Nan

2012-11-01

Soft extended emission (EE) following initial hard spikes up to 100 s was observed with Swift/BAT for about half of known short-type gamma-ray bursts (SGRBs). This challenges the conversional central engine models of SGRBs, i.e., compact star merger models. In the framework of black-hole-neutron-star merger models, we study the roles of radial angular momentum transfer in the disk and the magnetic barrier around the black hole in the activity of SGRB central engines. We show that radial angular momentum transfer may significantly prolong the lifetime of the accretion process, which may be divided into multiple episodes by the magnetic barrier. Our numerical calculations based on models of neutrino-dominated accretion flows suggest that disk mass is critical for producing the observed EE. In the case of the mass being ~0.8 M ⊙, our model can reproduce the observed timescale and luminosity of both the main and the EE episodes in a reasonable parameter set. The predicted luminosity of the EE component is lower than the observed EE within about one order of magnitude and the timescale is shorter than 20 s if the disk mass is ~0.2 M ⊙. Swift/BAT-like instruments may be not sensitive enough to detect the EE component in this case. We argue that the EE component could be a probe for the merger process and disk formation for compact star mergers.

Heat transfer in thin, compact heat exchangers with circular, rectangular, or pin-fin flow passages

NASA Technical Reports Server (NTRS)

Olson, D. A.

1992-01-01

Heat transfer and pressure drop have been measured of three thin, compact heat exchangers in helium gas at 3.5 MPa and higher, with Reynolds numbers of 450 to 36,000. The flow geometries for the three heat exchanger specimens were: circular tube, rectangular channel, and staggered pin fin with tapered pins. The specimens were heated radiatively at heat fluxes up to 77 W/sq cm. Correlations were developed for the isothermal friction factor as a function of Reynolds number, and for the Nusselt number as a function of Reynolds number and the ratio of wall temperature to fluid temperature. The specimen with the pin fin internal geometry had significantly better heat transfer than the other specimens, but it also had higher pressure drop. For certain conditions of helium flow and heating, the temperature more than doubled from the inlet to the outlet of the specimens, producing large changes in gas velocity, density, viscosity, and thermal conductivity. These changes in properties did not affect the correlations for friction factor and Nusselt number in turbulent flow.

Effects of biochar on hydraulic conductivity of compacted kaolin clay.

PubMed

Wong, James Tsz Fung; Chen, Zhongkui; Wong, Annie Yan Yan; Ng, Charles Wang Wai; Wong, Ming Hung

2018-03-01

Compacted clay is widely used as capillary barriers in landfill final cover system. Recently, biochar amended clay (BAC) has been proposed as a sustainable alternative cover material. However, the effects of biochar on saturated hydraulic conductivity (k sat ) of clay with high degree of compaction is not yet understood. The present study aims to investigate the effects of biochar on k sat of compacted kaolin clay. Soil specimens were prepared by amending kaolin clay with biochar derived from peanut-shell at 0, 5 and 20% (w/w). The k sat of soil specimens was measured using a flexible water permeameter. The effects of biochar on the microstructure of the compacted clay was also investigated using MIP. Adding 5% and 20% of biochar increased the k sat of compacted kaolin clay from 1.2 × 10 -9 to 2.1 × 10 -9 and 1.3 × 10 -8 ms -1 , respectively. The increase in k sat of clay was due to the shift in pore size distribution of compacted biochar-amended clay (BAC). MIP results revealed that adding 20% of biochar shifted the dominant pore diameter of clay from 0.01-0.1 μm (meso- and macropores) to 0.1-4 μm (macropores). Results reported in this communication revealed that biochar application increased the k sat of compacted clay, and the increment was positively correlated to the biochar percentage. Copyright © 2017 Elsevier Ltd. All rights reserved.

Effectiveness of Shot Peening In Suppressing Fatigue Cracking At Non-Metallic Inclusions In Udimet(Registered Trademark)720

NASA Technical Reports Server (NTRS)

Barrie, Robert L.; Gabb, Timothy P.; Telesman, Jack; Kantzos, Peter T.; Prescenzi, Anthony; Biles, T.; Bonacuse, P. J.

2006-01-01

The fatigue lives of modern powder metallurgy disk alloys can be reduced over an order of magnitude by cracking at inherent non-metallic inclusions. The objective of this work was to study the effectiveness of shot peening in suppressing LCF crack initiation and growth at surface nonmetallic inclusions. Inclusions were carefully introduced at elevated levels during powder metallurgy processing of the nickel-base disk superalloy Udimet 720. Multiple strain-controlled fatigue tests were then performed on machined specimens with and without shot peened test sections at 427 C and 650 C. The low cycle fatigue lives and failure initiation sites varied as functions of inclusion content, shot peening, and fatigue conditions. A large majority of the failures in as-machined specimens with the introduced inclusions occurred at cracks initiating from inclusions intersecting the specimen surface. These inclusions reduced fatigue life by up to 100X, when compared to lives of material without inclusions residing at specimen surface. Large inclusions produced the greatest reductions in life for tests at low strain ranges and high strain ratios. Shot peening improved life in many cases by reducing the most severe effects of inclusions.

Thermal-Fatigue Crack-Growth Characteristics and Mechanical Strain Cycling Behavior of A-286 Discaloy, and 16-25-6 Austenitic Steels

NASA Technical Reports Server (NTRS)

Smith, Robert W.; Smith, Gordon T.

1960-01-01

Thermal-fatigue crack-growth characteristics of notched- and unnotched-disk specimens of A-286, Discaloy, hot-cold worked 16-25-6, and overaged 16-25-6 were experimentally studied. Separately controlled variables were total strain range (0.0043 to 0.0079 in./in.), maximum cycle temperature (1300 and 1100 F), and hold time at maximum temperature (O and 5 min). A limited number of mechanical, push-pull, constant-strain cycle tests at room temperature were made using notched and un-notched bars of the same materials. In these tests the number of cycles to failure as well as the variation of load change with accumulated cycles was measured, and the effects of mean stress were observed. Constant-strain-range mechanical-fatigue tests at room temperature revealed notched-bar fatigue life to be strongly influenced by mean stress. For a specific strain range, the longest fatigue life was always found to be associated with the least-tensile (or most compressive) mean stress. By defining thermal-fatigue life as the number of cycles required to produce a crack area of 6000 square mils, the relative thermal-fatigue resistances of the test materials were established. Notched-disk specimens of A-286 and Discaloy steels exhibited longer fatigue lives than either hot-cold worked or overaged 16-25-6. On the other hand, unnotched-disk specimens of Discaloy and hot-cold worked 16-25-6 had longer lives than A-286 and overaged 16-25-6. Separation of the crack-growth data into microstage and macrostage periods revealed that the macrostage period accounted for the greatest part of the difference among materials when tested in the notched configuration, while the microstage was largely responsible for the differences encountered in unnotched disks.

Cyclic Oxidation and Hot Corrosion of NiCrY-Coated Disk Superalloy

NASA Technical Reports Server (NTRS)

Gabb, Tim; Miller, R. A.; Sudbrack, C. K.; Draper, S. L.; Nesbitt, J.; Telesman, J.; Ngo, V.; Healy, J.

2015-01-01

Powder metallurgy disk superalloys have been designed for higher engine operating temperatures through improvement of their strength and creep resistance. Yet, increasing disk application temperatures to 704 C and higher could enhance oxidation and activate hot corrosion in harmful environments. Protective coatings could be necessary to mitigate such attack. Cylindrical coated specimens of disk superalloys LSHR and ME3 were subjected to thermal cycling to produce cyclic oxidation in air at a maximum temperature of 760 C. The effects of substrate roughness and coating thickness on coating integrity after cyclic oxidation were considered. Selected coated samples that had cyclic oxidation were then subjected to accelerated hot corrosion tests. The effects of this cyclic oxidation on resistance to subsequent hot corrosion attack were examined.

The Effectiveness of a NiCrY-Coating on a Powder Metallurgy Disk Superalloy

NASA Technical Reports Server (NTRS)

Gabb, Timothy P.; Miller, Robert A.; Nesbitt, James A.; Draper, Susan L.; Rogers, Richard B.; Telesman, Jack

2018-01-01

Protective ductile coatings could be necessary to mitigate oxidation and corrosion attack on superalloy disks in some turbine engine applications. However, the effects of coatings on fatigue life of the disk during service are an important concern. The objective of this study was to investigate how such a coating could perform after varied post-coating processing. Cylindrical gage fatigue specimens of powder metallurgy-processed disk superalloy LSHR were coated with a NiCrY coating, shot peened, preparation treated, exposed, and then subjected to fatigue at high temperature. The effects of varied shot peening, preparation treatment, and exposures on fatigue life with and without the coating were compared. Each of these variables and several of their interactions significantly influenced fatigue life.

Retention of Compressive Residual Stresses Introduced by Shot Peening in a Powder Metal Disk Superalloy

NASA Technical Reports Server (NTRS)

Gabb, Timothy P.; Danetti, Andrew; Draper, Susan L.; Locci, Ivan E.; Telesman, Jack

2016-01-01

The fatigue lives of disk superalloys can be increased by shot peening their surfaces, to induce compressive residual stresses near the surface that impede cracking there. As disk application temperatures increase for improved efficiency, the persistence of these beneficial stresses could be impaired, especially with continued fatigue cycling. The objective of this work was to study the retention of residual stresses introduced by shot peening, when subjected to fatigue and high temperatures. Fatigue specimens of powder metallurgy processed nickel-base disk superalloy ME3 were prepared with consistent processing and heat treatment. They were then shot peened using varied conditions. Strain-controlled fatigue cycles were run at room temperature and 704 C, to allow re-assessment of residual stresses.

The use of low cost compact cameras with focus stacking functionality in entomological digitization projects

PubMed Central

Mertens, Jan E.J.; Roie, Martijn Van; Merckx, Jonas; Dekoninck, Wouter

2017-01-01

Abstract Digitization of specimen collections has become a key priority of many natural history museums. The camera systems built for this purpose are expensive, providing a barrier in institutes with limited funding, and therefore hampering progress. An assessment is made on whether a low cost compact camera with image stacking functionality can help expedite the digitization process in large museums or provide smaller institutes and amateur entomologists with the means to digitize their collections. Images of a professional setup were compared with the Olympus Stylus TG-4 Tough, a low-cost compact camera with internal focus stacking functions. Parameters considered include image quality, digitization speed, price, and ease-of-use. The compact camera’s image quality, although inferior to the professional setup, is exceptional considering its fourfold lower price point. Producing the image slices in the compact camera is a matter of seconds and when optimal image quality is less of a priority, the internal stacking function omits the need for dedicated stacking software altogether, further decreasing the cost and speeding up the process. In general, it is found that, aware of its limitations, this compact camera is capable of digitizing entomological collections with sufficient quality. As technology advances, more institutes and amateur entomologists will be able to easily and affordably catalogue their specimens. PMID:29134038

The advantage of an alternative substrate over Al/NiP disks

NASA Astrophysics Data System (ADS)

Jiaa, Chi L.; Eltoukhy, Atef

1994-02-01

Compact-size disk drives with high storage densities are in high demand due to the popularity of portable computers and workstations. The contact-start-stop (CSS) endurance performance must improve in order to accomodate the higher number of on/off cycles. In this paper, we looked at 65 mm thin-film canasite substrate disks and evaluated their mechanical performance. We compared them with conventional aluminum NiP-plated disks in surface topography, take-off time with changes of skew angles and radius, CSS, drag test and glide height performance, and clamping effect. In addition, a new post-sputter process aimed at the improvement of take-off and glide as well as CSS performances was investigated and demonstrated for the canasite disks. From the test results, it is indicated that canasite achieved a lower take-off velocity, higher clamping resistance, and better glide height and CSS endurance performance. This study concludes that a new generation disk drive equipped with canasite substrate disks will consume less power from the motor due to faster take-off and lighter weight, achieve higher recording density since the head flies lower, can better withstand damage from sliding friction during the CSS operations, and will be less prone to disk distortion from clamping due to its superior mechanical properties.

Implementation of the soil compactor analyzer into test method TEX-113-E : technical report.

DOT National Transportation Integrated Search

2012-04-01

Test method Tex-113-E prepares laboratory aggregate base test specimens with an impact hammer : compactor. These specimens are used for compaction characteristics and design tests. Although the : historical Tex-113-E required a certain amount of comp...

Magnetically driven jets and winds: Exact solutions

NASA Technical Reports Server (NTRS)

Contopoulos, J.; Lovelace, R. V. E.

1994-01-01

We present a general class of self-similar solutions of the full set of MHD equations that include matter flow, electromagnetic fields, pressure, and gravity. The solutions represent axisymmetric, time-independent, nonrelativistic, ideal, magnetohydrodynamic, collimated outflows (jet and winds) from magnetized accretion disks around compact objects. The magnetic field extracts angular momentum from the disk, accelerates the outflows perpedicular to the disk, and provides collimation at large distances. The terminal outflow velocities are of the order of or greater than the rotational velocity of the disk at the base of the flow. When a nonzero electric current flows along the jet, the outflow radius oscillates with axial distance, whereas when the total electric current is zero (with the return current flowing across the jet's cross section), the outflow radius increase to a maximum and then decreases. The method can also be applied to relativistic outflows.

Publication of science data on CD-ROM: A guide and example

NASA Technical Reports Server (NTRS)

Angelici, Gary; Skiles, J. W.

1993-01-01

CD-ROM (Compact Disk-Read Only Memory) is becoming the standard media not only in audio recording, but also in the publication of data and information accessible on many computer platforms. Little has been written about the complicated process involved in creating easy-to-use, high quality, and useful CD-ROM's containing scientific data. This document is a manual designed to aid those who are responsible for the publication of scientific data on CD-ROM. All aspects and steps of the procedure are covered, from feasibility assessment through disk design, data preparation, disc mastering, and CD-ROM distribution. General advice and actual examples are based on lessons learned from the publication of scientific data for an interdisciplinary field experiment. Appendices include actual files from a CD-ROM, a purchase request for CD-ROM mastering services, and the disk art for the first disk published for the project.

The dynamics and fueling of active nuclei

NASA Technical Reports Server (NTRS)

Norman, C.; Silk, J.

1983-01-01

It is generally believed that quasars and active galactic nuclei produce their prodigious luminosities in connection with the release of gravitational energy associated with accretion and infall of matter onto a compact central object. In the present analysis, it is assumed that the central object is a massive black hole. The fact that a black hole provides the deepest possible central potential well does imply that it is the most natural candidate for the central engine. It is also assumed that the quasar is associated with the nucleus of a conventional galaxy. A number of difficulties arise in connection with finding a suitable stellar fueling model. A simple scheme is discussed for resolving these difficulties. Attention is given to fueling in a nonaxisymmetric potential, the effects of a massive accretion disk, and the variability in the disk luminosity caused by star-disk collisions assuming that the energy deposited in the disk is radiated.

Digitized molecular diagnostics: reading disk-based bioassays with standard computer drives.

PubMed

Li, Yunchao; Ou, Lily M L; Yu, Hua-Zhong

2008-11-01

We report herein a digital signal readout protocol for screening disk-based bioassays with standard optical drives of ordinary desktop/notebook computers. Three different types of biochemical recognition reactions (biotin-streptavidin binding, DNA hybridization, and protein-protein interaction) were performed directly on a compact disk in a line array format with the help of microfluidic channel plates. Being well-correlated with the optical darkness of the binding sites (after signal enhancement by gold nanoparticle-promoted autometallography), the reading error levels of prerecorded audio files can serve as a quantitative measure of biochemical interaction. This novel readout protocol is about 1 order of magnitude more sensitive than fluorescence labeling/scanning and has the capability of examining multiplex microassays on the same disk. Because no modification to either hardware or software is needed, it promises a platform technology for rapid, low-cost, and high-throughput point-of-care biomedical diagnostics.

Effects of C5/C6 Intervertebral Space Distraction Height on Pressure on the Adjacent Intervertebral Disks and Articular Processes and Cervical Vertebrae Range of Motion.

PubMed

Lu, Tingsheng; Luo, Chunshan; Ouyang, Beiping; Chen, Qiling; Deng, Zhongliang

2018-04-25

BACKGROUND This study aimed to investigate the association between range of motion of the cervical vertebrae and various C5/C6 intervertebral space distraction heights. MATERIAL AND METHODS The cervical vertebrae from 6 fresh adult human cadavers were used to prepare the models. Changes in C4/C5 and C6/C7 intervertebral disk pressures, articular process pressure, and range of motion of the cervical vertebrae before and after the distraction of the C5/C6 intervertebral space at benchmark heights of 100%, 120%, 140%, and 160% were tested under different exercise loads. RESULTS The pressure on the adjacent intervertebral disks was highest with the standing upright position before distraction, varied with different positions of the specimens and distraction heights after distraction, and was closest to that before distraction at a distraction height of 120% (P<0.05). The pressure of the adjacent articular processes was highest with left and right rotations before distraction, varied with different positions of the specimens and distraction heights after distraction, and was lowest under the same exercise load with different positions at a distraction height of 120% (P<0.05). The ranges of motion of the cervical vertebrae and intervertebral disks were largest without distraction and at a distraction height of 120% after distraction, respectively (P<0.05). CONCLUSIONS When removing the C5/C6 intervertebral disk and implanting an intervertebral bone graft, a benchmark height of 120% had little influence on the pressure of the adjacent intervertebral disks and articular processes and range of motion of the cervical vertebrae and is therefore an appropriate intervertebral space distraction height.

Effects of C5/C6 Intervertebral Space Distraction Height on Pressure on the Adjacent Intervertebral Disks and Articular Processes and Cervical Vertebrae Range of Motion

PubMed Central

Lu, Tingsheng; Luo, Chunshan; Ouyang, Beiping; Chen, Qiling

2018-01-01

Background This study aimed to investigate the association between range of motion of the cervical vertebrae and various C5/C6 intervertebral space distraction heights. Material/Methods The cervical vertebrae from 6 fresh adult human cadavers were used to prepare the models. Changes in C4/C5 and C6/C7 intervertebral disk pressures, articular process pressure, and range of motion of the cervical vertebrae before and after the distraction of the C5/C6 intervertebral space at benchmark heights of 100%, 120%, 140%, and 160% were tested under different exercise loads. Results The pressure on the adjacent intervertebral disks was highest with the standing upright position before distraction, varied with different positions of the specimens and distraction heights after distraction, and was closest to that before distraction at a distraction height of 120% (P<0.05). The pressure of the adjacent articular processes was highest with left and right rotations before distraction, varied with different positions of the specimens and distraction heights after distraction, and was lowest under the same exercise load with different positions at a distraction height of 120% (P<0.05). The ranges of motion of the cervical vertebrae and intervertebral disks were largest without distraction and at a distraction height of 120% after distraction, respectively (P<0.05). Conclusions When removing the C5/C6 intervertebral disk and implanting an intervertebral bone graft, a benchmark height of 120% had little influence on the pressure of the adjacent intervertebral disks and articular processes and range of motion of the cervical vertebrae and is therefore an appropriate intervertebral space distraction height. PMID:29693646

The Effects of Hot Corrosion Pits on the Fatigue Resistance of a Disk Superalloy

NASA Technical Reports Server (NTRS)

Gabb, Timothy P.; Telesman, Jack; Hazel, Brian; Mourer, David P.

2009-01-01

The effects of hot corrosion pits on low cycle fatigue life and failure modes of the disk superalloy ME3 were investigated. Low cycle fatigue specimens were subjected to hot corrosion exposures producing pits, then tested at low and high temperatures. Fatigue lives and failure initiation points were compared to those of specimens without corrosion pits. Several tests were interrupted to estimate the fraction of fatigue life that fatigue cracks initiated at pits. Corrosion pits significantly reduced fatigue life by 60 to 98 percent. Fatigue cracks initiated at a very small fraction of life for high temperature tests, but initiated at higher fractions in tests at low temperature. Critical pit sizes required to promote fatigue cracking were estimated, based on measurements of pits initiating cracks on fracture surfaces.

Disk Alloy Development

NASA Technical Reports Server (NTRS)

Gabb, Tim; Gayda, John; Telesman, Jack

2001-01-01

The advanced powder metallurgy disk alloy ME3 was designed using statistical screening and optimization of composition and processing variables in the NASA HSR/EPM disk program to have extended durability at 1150 to 1250 "Fin large disks. Scaled-up disks of this alloy were produced at the conclusion of this program to demonstrate these properties in realistic disk shapes. The objective of the UEET disk program was to assess the mechanical properties of these ME3 disks as functions of temperature, in order to estimate the maximum temperature capabilities of this advanced alloy. Scaled-up disks processed in the HSR/EPM Compressor / Turbine Disk program were sectioned, machined into specimens, and tested in tensile, creep, fatigue, and fatigue crack growth tests by NASA Glenn Research Center, in cooperation with General Electric Engine Company and Pratt & Whitney Aircraft Engines. Additional sub-scale disks and blanks were processed and tested to explore the effects of several processing variations on mechanical properties. Scaled-up disks of an advanced regional disk alloy, Alloy 10, were used to evaluate dual microstructure heat treatments. This allowed demonstration of an improved balance of properties in disks with higher strength and fatigue resistance in the bores and higher creep and dwell fatigue crack growth resistance in the rims. Results indicate the baseline ME3 alloy and process has 1300 to 1350 O F temperature capabilities, dependent on detailed disk and engine design property requirements. Chemistry and process enhancements show promise for further increasing temperature capabilities.

Micromagnetic structure in Co-alloy thin films and its correlation with microstructure

NASA Astrophysics Data System (ADS)

Tang, Kai

The development of magnetic hard disk recording has resulted in an increase of recording density in an accelerated pace. How to maintain the increasingly smaller bits with low noise presents a tremendous challenge to the recording media, which requires detailed study of micromagnetic structure of the media to understand the noise mechanism, and elucidation of the correlation between the micromagnetic structure and microstructure to systematically develop media materials and tailor their microstructure. Lorentz transmission electron microscopy (LTEM) is a high-resolution magnetic imaging technique. However, it requires uniformly thin specimens, which cannot be produced by conventional TEM specimen preparation methods. Consequently, its application to real computer magnetic hard disks has been limited. In this dissertation, a combined dimpling and chemical etching method is introduced to prepare specimens directly from the unmodified hard disks with the typical C/Co alloy/Cr/NiP/Al (substrate) structure. The specimens typically have 2000 μmsp2 or larger electron transparent areas of Co alloy/Cr films with uniform thickness, which are suitable for LTEM observation. This method is applicable to disks with both smooth and mechanically textured substrates. In this work, LTEM has been employed to study recorded patterns in real hard disks. Magnetic recording was performed on a standard spin stand. Bits of densities from 15 to 100 kfci were examined with head skew angles of 0sp° and 20sp°, respectively. We also compared tracks recorded on dc-erased disks with those on as-deposited disks. We observed magnetic ripples within the tracks and the inter-track regions, magnetic vortices of 0.1-0.2 mum in diameter at the bit-transitions, and curved magnetic domain walls in the track-edge regions resulting from the "dog-bone" shaped head field profile. Our results also indicate that the micromagnetic structure at the track edges is influenced by head skew and magnetization direction in the inter-track regions. The LTEM results are combined with MFM observations to provide further understanding. The study has concentrated on isotropic media on smooth substrates since low head-to-medium spacing required by high recording density demonstrates the need for this type of media. The recorded tracks are remanent magnetic states after a strong (head) magnetic field was applied. We also examined an ac-erased state, in which the effect of external field is removed. Magnetic vortices are identified, in which small crystal grains form magnetic clusters and these clusters then form closed-fluxed vortices. The size of these vortices is estimated to be around 1.0-1.5 mum, about 10 times larger than that found in the bit-transition regions. The smaller vortex sizes in the bit-transition regions may result from constraints from adjacent bits as well as the difference in magnetic processes generating these states. (Abstract shortened by UMI.)

Carbon nanotube mode-locked vertical external-cavity surface-emitting laser

NASA Astrophysics Data System (ADS)

Seger, K.; Meiser, N.; Choi, S. Y.; Jung, B. H.; Yeom, D.-I.; Rotermund, F.; Okhotnikov, O.; Laurell, F.; Pasiskevicius, V.

2014-03-01

Mode-locking an optically pumped semiconductor disk laser has been demonstrated using low-loss saturable absorption containing a mixture of single-walled carbon nanotubes in PMM polymer. The modulator was fabricated by a simple spin-coating technique on fused silica substrate and was operating in transmission. Stable passive fundamental modelocking was obtained at a repetition rate of 613 MHz with a pulse length of 1.23 ps. The mode-locked semiconductor disk laser in a compact geometry delivered a maximum average output power of 136 mW at 1074 nm.

Direct detection of scattered light gaps in the transitional disk around HD 97048 with VLT/SPHERE

NASA Astrophysics Data System (ADS)

Ginski, C.; Stolker, T.; Pinilla, P.; Dominik, C.; Boccaletti, A.; de Boer, J.; Benisty, M.; Biller, B.; Feldt, M.; Garufi, A.; Keller, C. U.; Kenworthy, M.; Maire, A. L.; Ménard, F.; Mesa, D.; Milli, J.; Min, M.; Pinte, C.; Quanz, S. P.; van Boekel, R.; Bonnefoy, M.; Chauvin, G.; Desidera, S.; Gratton, R.; Girard, J. H. V.; Keppler, M.; Kopytova, T.; Lagrange, A.-M.; Langlois, M.; Rouan, D.; Vigan, A.

2016-11-01

Aims: We studied the well-known circumstellar disk around the Herbig Ae/Be star HD 97048 with high angular resolution to reveal undetected structures in the disk which may be indicative of disk evolutionary processes such as planet formation. Methods: We used the IRDIS near-IR subsystem of the extreme adaptive optics imager SPHERE at the ESO/VLT to study the scattered light from the circumstellar disk via high resolution polarimetry and angular differential imaging. Results: We imaged the disk in unprecedented detail and revealed four ring-like brightness enhancements and corresponding gaps in the scattered light from the disk surface with radii between 39 au and 341 au. We derived the inclination and position angle as well as the height of the scattering surface of the disk from our observational data. We found that the surface height profile can be described by a single power law up to a separation 270 au. Using the surface height profile we measured the scattering phase function of the disk and found that it is consistent with theoretical models of compact dust aggregates. We discuss the origin of the detected features and find that low mass (≤1 MJup) nascent planets are a possible explanation. Based on data collected at the European Southern Observatory, Chile (ESO Programs 096.C-0248, 096.C-0241, 077.C-0106).

Problems Associated with Statistical Pattern Recognition of Acoustic Emission Signals in a Compact Tension Fatigue Specimen

NASA Technical Reports Server (NTRS)

Hinton, Yolanda L.

1999-01-01

Acoustic emission (AE) data were acquired during fatigue testing of an aluminum 2024-T4 compact tension specimen using a commercially available AE system. AE signals from crack extension were identified and separated from noise spikes, signals that reflected from the specimen edges, and signals that saturated the instrumentation. A commercially available software package was used to train a statistical pattern recognition system to classify the signals. The software trained a network to recognize signals with a 91-percent accuracy when compared with the researcher's interpretation of the data. Reasons for the discrepancies are examined and it is postulated that additional preprocessing of the AE data to focus on the extensional wave mode and eliminate other effects before training the pattern recognition system will result in increased accuracy.

Diagnosis of Enterocytozoon bieneusi by PCR in Stool Samples Eluted from Filter Paper Disks

PubMed Central

Carnevale, Silvana; Velásquez, Jorge N.; Labbé, Jorge H.; Chertcoff, Agustín; Cabrera, Marta G.; Rodríguez, Mónica I.

2000-01-01

We report a PCR-based assay for the detection of Enterocytozoon bieneusi. We extracted DNA from feces which had been applied to filter paper disks and evaluated four preserving solutions. Infected specimens were identified by electrophoresis of amplicons from concentrated formalin-fixed samples and unconcentrated fresh feces. Our findings demonstrate that this methodology is effective for sample collection, mailing, and diagnosis of this pathogen. PMID:10799469

Videodisc Technology.

ERIC Educational Resources Information Center

Ullmer, Eldon J.

Developed as a service to the health sciences community, this monograph is intended as an introduction to interactive videodisk technology. It describes both videodisk and compact disk technologies and different videodisk player formats, and discusses some of the major factors that educators considering videodisk adoption should consider. The…

Digital Equipment Corporation's CRDOM Software and Database Publications.

ERIC Educational Resources Information Center

Adams, Michael Q.

1986-01-01

Acquaints information professionals with Digital Equipment Corporation's compact optical disk read-only-memory (CDROM) search and retrieval software and growing library of CDROM database publications (COMPENDEX, Chemical Abstracts Services). Highlights include MicroBASIS, boolean operators, range operators, word and phrase searching, proximity…

A massive, dead disk galaxy in the early Universe.

PubMed

Toft, Sune; Zabl, Johannes; Richard, Johan; Gallazzi, Anna; Zibetti, Stefano; Prescott, Moire; Grillo, Claudio; Man, Allison W S; Lee, Nicholas Y; Gómez-Guijarro, Carlos; Stockmann, Mikkel; Magdis, Georgios; Steinhardt, Charles L

2017-06-21

At redshift z = 2, when the Universe was just three billion years old, half of the most massive galaxies were extremely compact and had already exhausted their fuel for star formation. It is believed that they were formed in intense nuclear starbursts and that they ultimately grew into the most massive local elliptical galaxies seen today, through mergers with minor companions, but validating this picture requires higher-resolution observations of their centres than is currently possible. Magnification from gravitational lensing offers an opportunity to resolve the inner regions of galaxies. Here we report an analysis of the stellar populations and kinematics of a lensed z = 2.1478 compact galaxy, which-surprisingly-turns out to be a fast-spinning, rotationally supported disk galaxy. Its stars must have formed in a disk, rather than in a merger-driven nuclear starburst. The galaxy was probably fed by streams of cold gas, which were able to penetrate the hot halo gas until they were cut off by shock heating from the dark matter halo. This result confirms previous indirect indications that the first galaxies to cease star formation must have gone through major changes not just in their structure, but also in their kinematics, to evolve into present-day elliptical galaxies.

Accretion torques in X-ray pulsars

NASA Technical Reports Server (NTRS)

Rappaport, S.; Joss, P. C.

1977-01-01

An analysis of the accretion process in an X-ray pulsar, whereby angular momentum is transferred to the star and its rotation period is changed, is presented, and an expression for the fractional rate of change of the pulse period in terms of X-ray luminosity and other star parameters is derived. It is shown that observed characteristic spin-up time scales for seven X-ray pulsars strongly support the view that in every source (1) the pulse period reflects the rotation period of a compact object, (2) the accretion is mediated by a disk surrounding the compact object and rotating in the same sense, and (3) the compact object is a neutron star rather than a white dwarf.

Compact ultrafast semiconductor disk laser for nonlinear imaging in living organisms

NASA Astrophysics Data System (ADS)

Aviles-Espinosa, Rodrigo; Filippidis, G.; Hamilton, Craig; Malcolm, Graeme; Weingarten, Kurt J.; Südmeyer, Thomas; Barbarin, Yohan; Keller, Ursula; Artigas, David; Loza-Alvarez, Pablo

2011-03-01

Ultrashort pulsed laser systems (such as Ti:sapphire) have been used in nonlinear microscopy during the last years. However, its implementation is not straight forward as they are maintenance-intensive, bulky and expensive. These limitations have prevented their wide-spread use for nonlinear imaging, especially in "real-life" biomedical applications. In this work we present the suitability of a compact ultrafast semiconductor disk laser source, with a footprint of 140x240x70 mm, to be used for nonlinear microscopy. The modelocking mechanism of the laser is based on a quantumdot semiconductor saturable absorber mirror (SESAM). The laser delivers an average output power of 287 mW with 1.5 ps pulses at 500 MHz, corresponding to a peak power of 0.4 kW. Its center wavelength is 965 nm which is ideally suited for two-photon excitation of the widely used Green Fluorescent Protein (GFP) marker as it virtually matches its twophoton action cross section. We reveal that it is possible to obtain two photon excited fluorescence images of GFP labeled neurons and secondharmonic generation images of pharynx and body wall muscles in living C. elegans nematodes. Our results demonstrate that this compact laser is well suited for long-term time-lapse imaging of living samples as very low powers provide a bright signal. Importantly this non expensive, turn-key, compact laser system could be used as a platform to develop portable nonlinear bio-imaging devices, facilitating its wide-spread adoption in "real-life" applications.

Gemini Planet Imager observations of the AU Microscopii debris disk: Asymmetries within one arcsecond

DOE PAGES

Wang, Jason J.; Graham, James R.; Pueyo, Laurent; ...

2015-09-23

We present Gemini Planet Imager (GPI) observations of AU Microscopii, a young M dwarf with an edge-on, dusty debris disk. Integral field spectroscopy and broadband imaging polarimetry were obtained during the commissioning of GPI. In our broadband imaging polarimetry observations, we detect the disk only in total intensity and find asymmetries in the morphology of the disk between the southeast (SE) and northwest (NW) sides. The SE side of the disk exhibits a bump at 1'' (10 AU projected separation) that is three times more vertically extended and three times fainter in peak surface brightness than the NW side atmore » similar separations. This part of the disk is also vertically offset by 69 ± 30 mas to the northeast at 1'' when compared to the established disk midplane and is consistent with prior Atacama Large Millimeter/submillimeter Array and Hubble Space Telescope/Space Telescope Imaging Spectrograph observations. We see hints that the SE bump might be a result of detecting a horizontal sliver feature above the main disk that could be the disk backside. Alternatively, when including the morphology of the NW side, where the disk midplane is offset in the opposite direction ~50 mas between 0farcs4 and 1farcs2, the asymmetries suggest a warp-like feature. Using our integral field spectroscopy data to search for planets, we are 50% complete for ~4 MJup planets at 4 AU. Lastly, we detect a source, resolved only along the disk plane, that could either be a candidate planetary mass companion or a compact clump in the disk.« less

Evolution of the protolunar disk: Dynamics, cooling timescale and implantation of volatiles onto the Earth

NASA Astrophysics Data System (ADS)

Charnoz, Sébastien; Michaut, Chloé

2015-11-01

It is thought that the Moon accreted from the protolunar disk that was assembled after the last giant impact on Earth. Due to its high temperature, the protolunar disk may act as a thermochemical reactor in which the material is processed before being incorporated into the Moon. Outstanding issues like devolatilisation and istotopic evolution are tied to the disk evolution, however its lifetime, dynamics and thermodynamics are unknown. Here, we numerically explore the long term viscous evolution of the protolunar disk using a one dimensional model where the different phases (vapor and condensed) are vertically stratified. Viscous heating, radiative cooling, phase transitions and gravitational instability are accounted for whereas Moon's accretion is not considered for the moment. The viscosity of the gas, liquid and solid phases dictates the disk evolution. We find that (1) the vapor condenses into liquid in ∼10 years, (2) a large fraction of the disk mass flows inward forming a hot and compact liquid disk between 1 and 1.7 Earth's radii, a region where the liquid is gravitationally stable and can accumulate, (3) the disk finally solidifies in 103 to 105 years. Viscous heating is never balanced by radiative cooling. If the vapor phase is abnormally viscous, due to magneto-rotational instability for instance, most of the disk volatile components are transported to Earth leaving a disk enriched in refractory elements. This opens a way to form a volatile-depleted Moon and would suggest that the missing Moon's volatiles are buried today into the Earth. The disk cooling timescale may be long enough to allow for planet/disk isotopic equilibration. However large uncertainties on the disk physics remain because of the complexity of its multi-phased structure.

Quench Crack Behavior of Nickel-base Disk Superalloys

NASA Technical Reports Server (NTRS)

Gayda, John; Kantzos, Pete; Miller, Jason

2002-01-01

There is a need to increase the temperature capability of superalloy turbine disks to allow higher operating temperatures in advanced aircraft engines. When modifying processing and chemistry of disk alloys to achieve this capability, it is important to preserve the ability to use rapid cooling during supersolvus heat treatments to achieve coarse grain, fine gamma prime microstructures. An important step in this effort is an understanding of the key variables controlling the cracking tendencies of nickel-base disk alloys during quenching from supersolvus heat treatments. The objective of this study was to investigate the quench cracking tendencies of several advanced disk superalloys during simulated heat treatments. Miniature disk specimens were rapidly quenched after solution heat treatments. The responses and failure modes were compared and related to the quench cracking tendencies of actual disk forgings. Cracking along grain boundaries was generally observed to be operative. For the alloys examined in this study, the solution temperature not alloy chemistry was found to be the primary factor controlling quench cracking. Alloys with high solvus temperatures show greater tendency for quench cracking.

AN ULTRA-LOW-MASS AND SMALL-RADIUS COMPACT OBJECT IN 4U 1746-37?

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

Li, Zhaosheng; Qu, Zhijie; Guo, Yanjun

Photospheric radius expansion (PRE) bursts have already been used to constrain the masses and radii of neutron stars. RXTE observed three PRE bursts in 4U 1746-37, all with low touchdown fluxes. We discuss here the possibility of a low-mass neutron star in 4U 1746-37 because the Eddington luminosity depends on stellar mass. With typical values of hydrogen mass fraction and color correction factor, a Monte Carlo simulation was applied to constrain the mass and radius of a neutron star in 4U 1746-37. 4U 1746-37 has a high inclination angle. Two geometric effects, the reflection of the far-side accretion disk andmore » the obscuration of the near-side accretion disk, have also been included in the mass and radius constraints of 4U 1746-37. If the reflection of the far-side accretion disk is accounted for, a low-mass compact object (mass of 0.41 ± 0.14 M {sub ☉} and radius of 8.73 ± 1.54 km at 68% confidence) exists in 4U 1746-37. If another effect operated, 4U 1746-37 may contain an ultra-low-mass and small-radius object (M = 0.21 ± 0.06 M {sub ☉}, R = 6.26 ± 0.99 km at 68% confidence). Combining all possibilities, the mass of 4U 1746-37 is 0.41{sub −0.30}{sup +0.70} M{sub ⊙} at 99.7% confidence. For such low-mass neutron stars, it could be reproduced by a self-bound compact star, i.e., a quark star or quark-cluster star.« less

Lense-Thirring Precession and Quasi-periodic Oscillations in X-Ray Binaries

NASA Astrophysics Data System (ADS)

Marković , Dragoljub; Lamb, Frederick K.

1998-11-01

It has recently been suggested that gravitomagnetic precession of the inner part of the accretion disk, possibly driven by radiation torques, may be responsible for some of the quasi-periodic X-ray brightness oscillations (QPOs) and other spectral features with frequencies between 20 and 300 Hz observed in the power spectra of some low-mass binary systems containing accreting neutron stars and black hole candidates. We have explored the free and driven normal modes of geometrically thin disks in the presence of gravitomagnetic and radiation warping torques. We have found a family of low-frequency gravitomagnetic (LFGM) modes with precession frequencies that range from the lowest frequency allowed by the size of the disk up to a certain critical frequency ωcrit, which is ~1 Hz for a compact object of solar mass. The lowest frequency (lowest order) LFGM modes are similar to the previously known radiation warping modes, extend over much of the disk, and have damping rates >~10 times their precession frequencies. The highest frequency LFGM modes are tightly wound spiral corrugations of the disk that extend to ~10 times its inner radius and have damping rates >~103 times their precession frequencies. A radiation warping torque can cause a few of the lowest frequency LFGM modes to grow with time, but even a strong radiation warping torque has essentially no effect on the LFGM modes with frequencies >~10-4 Hz. We have also discovered a second family of high-frequency gravitomagnetic (HFGM) modes with precession frequencies that range from ωcrit up to slightly less than the gravitomagnetic precession frequency ωgm,i of a particle at the inner edge of the disk, which is 30 Hz if the disk extends inward to the innermost stable circular orbit around a 2 M⊙ compact object with dimensionless angular momentum cJ/GM2 = 0.2. The lowest frequency HFGM modes are very strongly damped and have warp functions and precession frequencies very similar to those of the highest frequency LFGM modes. In contrast, the highest frequency (lowest order) HFGM modes are very localized spiral corrugations of the inner disk and are weakly damped, with Q-values of ~2-50. We discuss the implications of our results for the observability of Lense-Thirring precession in X-ray binaries.

Cyclic Oxidation and Hot Corrosion of NiCrY-Coated Disk Superalloys

NASA Technical Reports Server (NTRS)

Gabb, Timothy P.; Miller, Robert A.; Sudbrack, Chantal K.; Draper, Susan L.; Nesbitt, James A.; Rogers, Richard B.; Telesman, Ignacy; Ngo, Vanda; Healy, Jonathan

2016-01-01

Powder metallurgy disk superalloys have been designed for higher engine operating temperatures through improvement of their strength and creep resistance. Yet, increasing disk application temperatures to 704 degrees Centigrade and higher could enhance oxidation and activate hot corrosion in harmful environments. Protective coatings could be necessary to mitigate such attack. Cylindrical coated specimens of disk superalloys LSHR and ME3 were subjected to thermal cycling to produce cyclic oxidation in air at a maximum temperature of 760 degrees Centigrade. The effects of substrate roughness and coating thickness on coating integrity after cyclic oxidation were considered. Selected coated samples that had cyclic oxidation were then subjected to accelerated hot corrosion tests. This cyclic oxidation did not impair the coating's resistance to subsequent hot corrosion pitting attack.

Note: Compact and light displacement sensor for a precision measurement system in large motion

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

Lee, Sang Heon, E-mail: shlee@andong.ac.kr

We developed a compact and light displacement sensor applicable to systems that require wide range motions of its sensing device. The proposed sensor utilized the optical pickup unit of the optical disk drive, which has been used applied to atomic force microscopy (AFM) because of its compactness and lightness as well as its high performance. We modified the structure of optical pickup unit and made the compact sensor driver attachable to a probe head of AFM to make large rotation. The feasibilities of the developed sensor for a general probe-moving measurement device and for probe-rotating AFM were verified. Moreover, amore » simple and precise measurement of alignment between centers of rotator and probe tip in probe-rotation AFM was experimentally demonstrated using the developed sensor.« less

Quiet, Computer at Work.

ERIC Educational Resources Information Center

Black, Claudia

Libraries are becoming information access points, not just book repositories. With greater distribution of printed materials, increased use of optical disks and other compact storage techniques, the emergence of publication on demand, and the proliferation of electronic databases, libraries without large collections will be able to provide prompt…

Advanced Composition and the Computerized Library.

ERIC Educational Resources Information Center

Hult, Christine

1989-01-01

Discusses four kinds of computerized access tools: online catalogs; computerized reference; online database searching; and compact disks and read only memory (CD-ROM). Examines how these technologies are changing research. Suggests how research instruction in advanced writing courses can be refocused to include the new technologies. (RS)

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

Wang, Jason J.; Graham, James R.; Pueyo, Laurent

We present Gemini Planet Imager (GPI) observations of AU Microscopii, a young M dwarf with an edge-on, dusty debris disk. Integral field spectroscopy and broadband imaging polarimetry were obtained during the commissioning of GPI. In our broadband imaging polarimetry observations, we detect the disk only in total intensity and find asymmetries in the morphology of the disk between the southeast (SE) and northwest (NW) sides. The SE side of the disk exhibits a bump at 1'' (10 AU projected separation) that is three times more vertically extended and three times fainter in peak surface brightness than the NW side atmore » similar separations. This part of the disk is also vertically offset by 69 ± 30 mas to the northeast at 1'' when compared to the established disk midplane and is consistent with prior Atacama Large Millimeter/submillimeter Array and Hubble Space Telescope/Space Telescope Imaging Spectrograph observations. We see hints that the SE bump might be a result of detecting a horizontal sliver feature above the main disk that could be the disk backside. Alternatively, when including the morphology of the NW side, where the disk midplane is offset in the opposite direction ~50 mas between 0farcs4 and 1farcs2, the asymmetries suggest a warp-like feature. Using our integral field spectroscopy data to search for planets, we are 50% complete for ~4 MJup planets at 4 AU. Lastly, we detect a source, resolved only along the disk plane, that could either be a candidate planetary mass companion or a compact clump in the disk.« less

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

Wang, Jason J.; Graham, James R.; De Rosa, Robert J.

We present Gemini Planet Imager (GPI) observations of AU Microscopii, a young M dwarf with an edge-on, dusty debris disk. Integral field spectroscopy and broadband imaging polarimetry were obtained during the commissioning of GPI. In our broadband imaging polarimetry observations, we detect the disk only in total intensity and find asymmetries in the morphology of the disk between the southeast (SE) and northwest (NW) sides. The SE side of the disk exhibits a bump at 1″ (10 AU projected separation) that is three times more vertically extended and three times fainter in peak surface brightness than the NW side atmore » similar separations. This part of the disk is also vertically offset by 69 ± 30 mas to the northeast at 1″ when compared to the established disk midplane and is consistent with prior Atacama Large Millimeter/submillimeter Array and Hubble Space Telescope/Space Telescope Imaging Spectrograph observations. We see hints that the SE bump might be a result of detecting a horizontal sliver feature above the main disk that could be the disk backside. Alternatively, when including the morphology of the NW side, where the disk midplane is offset in the opposite direction ∼50 mas between 0.″4 and 1.″2, the asymmetries suggest a warp-like feature. Using our integral field spectroscopy data to search for planets, we are 50% complete for ∼4 M{sub Jup} planets at 4 AU. We detect a source, resolved only along the disk plane, that could either be a candidate planetary mass companion or a compact clump in the disk.« less

Shrinking galaxy disks with fountain-driven accretion from the halo

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

Elmegreen, Bruce G.; Struck, Curtis; Hunter, Deidre A., E-mail: bge@watson.ibm.com, E-mail: curt@iastate.edu, E-mail: dah@lowell.edu

2014-12-01

Star formation in most galaxies requires cosmic gas accretion because the gas consumption time is short compared to the Hubble time. This accretion presumably comes from a combination of infalling satellite debris, cold flows, and condensation of hot halo gas at the cool disk interface, perhaps aided by a galactic fountain. In general, the accretion will have a different specific angular momentum than the part of the disk that receives it, even if the gas comes from the nearby halo. The gas disk then expands or shrinks over time. Here we show that condensation of halo gas at a ratemore » proportional to the star formation rate in the fountain model will preserve an initial shape, such as an exponential, with a shrinking scale length, leaving behind a stellar disk with a slightly steeper profile of younger stars near the center. This process is slow for most galaxies, producing imperceptible radial speeds, and it may be dominated by other torques, but it could be important for blue compact dwarfs, which tend to have large, irregular gas reservoirs and steep blue profiles in their inner stellar disks.« less

HST and Adaptive Optics Imaging of the Edge-on Circumtertiary Disk in the Young Triple System HV Tauri

NASA Astrophysics Data System (ADS)

Stapelfeldt, K. R.; Menard, F.; Brandner, W.; Padgett, D. L.; Krist, J. E.; Watson, A. M.

2000-12-01

Hubble Space Telescope images of the HV Tauri triple system show that HV Tau C appears as a compact bipolar nebula at visual wavelengths. Near-infrared adaptive optics observations made at the Canada France Hawaii Telescope show a similar morphology, and no directly visible star at wavelengths less than 2 microns. These results confirm the conclusions of Monin & Bouvier 2000, namely that HV Tau C is an optically thick circumstellar disk seen close to edge-on. The images are compared to scattered light models for circumstellar disks. We find that the HV Tau C disk has an outer radius of 85 AU, inclination of about 6 deg, gaussian scale height of 15 AU at its outer radius, and is flared. The thickness of the dark lane indicates a total disk mass about half that of Jupiter. There is clear evidence for declining dust opacity toward longer wavelengths, as the dust lane thickness shrinks by 30 between 0.8 and 2.2 microns; the trend is consistent with interstellar dust grains. Tidal truncation of the disk outer radius may have occurred in this system.

An evaluation of the susceptibility of V-4Cr-4Ti to stress corrosion cracking in room temperature DIII-D water

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

Kurtz, R.J.; Jones, R.H.; Johnson, W.R.

1997-04-01

Two fatigue precracked compact tension (CT) specimens of V-4Cr-4Ti were statically loaded to a stress intensity factor of about 30 MPa{radical}m in room temperature DIII-D water. The first specimen was tested for a period of about 30 days and the second specimen for about 54 days. At the conclusion of each test the specimens were fractured, and the fracture surfaces examined with a scanning electron microscope (SEM) to determine if SCC had occurred. No SCC was found in either test specimen.

CANDELS+3D-HST: Compact SFGs at z ∼ 2-3, the progenitors of the first quiescent galaxies

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

Barro, G.; Faber, S. M.; Koo, D. C.

We analyze the star-forming and structural properties of 45 massive (log(M/M{sub ☉}) >10) compact star-forming galaxies (SFGs) at 2 < z < 3 to explore whether they are progenitors of compact quiescent galaxies at z ∼ 2. The optical/NIR and far-IR Spitzer/Herschel colors indicate that most compact SFGs are heavily obscured. Nearly half (47%) host an X-ray-bright active galactic nucleus (AGN). In contrast, only about 10% of other massive galaxies at that time host AGNs. Compact SFGs have centrally concentrated light profiles and spheroidal morphologies similar to quiescent galaxies and are thus strikingly different from other SFGs, which typically aremore » disk-like and sometimes clumpy or irregular. Most compact SFGs lie either within the star formation rate (SFR)-mass main sequence (65%) or below it (30%), on the expected evolutionary path toward quiescent galaxies. These results show conclusively that galaxies become more compact before they lose their gas and dust, quenching star formation. Using extensive HST photometry from CANDELS and grism spectroscopy from the 3D-HST survey, we model their stellar populations with either exponentially declining (τ) star formation histories (SFHs) or physically motivated SFHs drawn from semianalytic models (SAMs). SAMs predict longer formation timescales and older ages ∼2 Gyr, which are nearly twice as old as the estimates of the τ models. Both models yield good spectral energy distribution fits, indicating that the systematic uncertainty in the age due to degeneracies in the SFH is of that order of magnitude. However, SAM SFHs better match the observed slope and zero point of the SFR-mass main sequence. Contrary to expectations, some low-mass compact SFGs (log(M/M{sub ☉}) =10-10.6) have younger ages but lower specific SFRs than that of more massive galaxies, suggesting that the low-mass galaxies reach the red sequence faster. If the progenitors of compact SFGs are extended SFGs, state-of-the-art SAMs show that mergers and disk instabilities (DIs) are both able to shrink galaxies, but DIs are more frequent (60% versus 40%) and form more concentrated galaxies. We confirm this result via high-resolution hydrodynamic simulations.« less

Invited Review Article: Review of centrifugal microfluidic and bio-optical disks

PubMed Central

Nolte, David D.

2009-01-01

Spinning biodisks have advantages that make them attractive for specialized biochip applications. The two main classes of spinning biodisks are microfluidic disks and bio-optical compact disks (BioCD). Microfluidic biodisks take advantage of noninertial pumping for lab-on-a-chip devices using noninertial valves and switches under centrifugal and Coriolis forces to distribute fluids about the disks. BioCDs use spinning-disk interferometry, under the condition of common-path phase quadrature, to perform interferometric label-free detection of molecular recognition and binding. The optical detection of bound molecules on a disk is facilitated by rapid spinning that enables high-speed repetitive sampling to eliminate 1∕f noise through common-mode rejection of intensity fluctuations and extensive signal averaging. Multiple quadrature classes have been developed, such as microdiffraction, in-line, phase contrast, and holographic adaptive optics. Thin molecular films are detected through the surface dipole density with a surface height sensitivity for the detection of protein spots that is approximately 1 pm. This sensitivity easily resolves a submonolayer of solid-support immobilized antibodies and their antigen targets. Fluorescence and light scattering provide additional optical detection techniques on spinning disks. Immunoassays have been applied to haptoglobin using protein A∕G immobilization of antibodies and to prostate specific antigen. Small protein spots enable scalability to many spots per disk for high-throughput and highly multiplexed immonoassays. PMID:19895047

No Disk Winds in Failed Black Hole Outbursts? New Observations of H1743-322

NASA Astrophysics Data System (ADS)

Neilsen, Joseph; Coriat, Mickael; Motta, Sara; Fender, Rob P.; Ponti, Gabriele; Corbel, Stephane

2016-04-01

The rich and complex physics of stellar-mass black holes in outburst is often referred to as the "disk-jet connection," a term that encapsulates the evolution of accretion disks over several orders of magnitude in Eddington ratio; through Compton scattering, reflection, and thermal emission; as they produce steady compact jets, relativistic plasma ejections, and (from high spectral resolution revelations of the last 15 years) massive, ionized disk winds. It is well established that steady jets are associated with radiatively inefficient X-ray states, and that winds tend to appear during states with more luminous disks, but the underlying physical processes that govern these connections (and their changes during state transitions) are not fully understood. I will present a unique perspective on the disk-wind-jet connection based on new Chandra HETGS, NuSTAR, and JVLA observations of the black hole H1743-322. Rather than following the usual outburst track, the 2015 outburst of H1743 fizzled: the disk never appeared in X-rays, and the source remained spectrally hard for the entire ~100 days. Remarkably, we find no evidence for any accretion disk wind in our data, even though H1743-322 has produced winds at comparable hard X-ray luminosities. I will discuss the implications of this "failed outburst" for our picture of winds from black holes and the astrophysics that governs them.

Flexural strength of self compacting fiber reinforced concrete beams using polypropylene fiber: An experimental study

NASA Astrophysics Data System (ADS)

Lisantono, Ade; Praja, Baskoro Abdi; Hermawan, Billy Nouwen

2017-11-01

One of the methods to increase the tensile strength of concrete is adding a fiber material into the concrete. While to reduce a noise in a construction project, a self compacting concrete was a good choices in the project. This paper presents an experimental study of flexural behavior and strength of self compacting fiber reinforced concrete (RC) beams using polypropylene fiber. The micro monofilament polypropylene fibers with the proportion 0.9 kg/m3 of concrete weight were used in this study. Four beam specimens were cast and tested in this study. Two beams were cast of self compacting reinforced concrete without fiber, and two beams were cast of self compacting fiber reinforced concrete using polypropylene. The beams specimen had the section of (180×260) mm and the length was 2000 mm. The beams had simple supported with the span of 1800 mm. The longitudinal reinforcements were using diameter of 10 mm. Two reinforcements of Ø10 mm were put for compressive reinforcement and three reinforcements of Ø10 mm were put for tensile reinforcement. The shear reinforcement was using diameter of 8 mm. The shear reinforcements with spacing of 100 mm were put in the one fourth near to the support and the spacing of 150 mm were put in the middle span. Two points loading were used in the testing. The result shows that the load-carrying capacity of the self compacting reinforced concrete beam using polypropylene was a little bit higher than the self compacting reinforced concrete beam without polypropylene. The increment of load-carrying capacity of self compacting polypropylene fiber reinforced concrete was not so significant because the increment was only 2.80 % compare to self compacting non fiber reinforced concrete. And from the load-carrying capacity-deflection relationship curves show that both the self compacting polypropylene fiber reinforced concrete beam and the self compacting non fiber reinforced concrete beam were ductile beams.

Improved Constraints on the Disk around MWC 349A from the 23 m LBTI

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

Sallum, S.; Eisner, J. A.; Hinz, P. M.

2017-07-20

We present new spatially resolved observations of MWC 349A from the Large Binocular Telescope Interferometer (LBTI), a 23 m baseline interferometer made up of two, co-mounted 8 m telescopes. MWC 349A is a B[e] star with an unknown evolutionary state. Proposed scenarios range from a young stellar object, to a B[e] supergiant, to a tight binary system. Radio continuum and recombination line observations of this source revealed a sub-arcsecond bipolar outflow surrounding an ∼100 mas circumstellar disk. Follow-up infrared studies detected the disk, and suggested that it may have skew and an inner clearing. Our new infrared interferometric observations, whichmore » have more than twice the resolution of previously published data sets, support the presence of both skew and a compact infrared excess. They rule out inner clearings with radii greater than ∼14 mas. We show the improvements in disk parameter constraints provided by LBTI, and discuss the inferred disk parameters in the context of the posited evolutionary states for MWC 349A.« less

An Inset CT Specimen for Evaluating Fracture in Small Samples of Material

PubMed Central

Yahyazadehfar, M.; Nazari, A.; Kruzic, J.J.; Quinn, G.D.; Arola, D.

2013-01-01

In evaluations on the fracture behavior of hard tissues and many biomaterials, the volume of material available to study is not always sufficient to apply a standard method of practice. In the present study an inset Compact Tension (inset CT) specimen is described, which uses a small cube of material (approximately 2×2×2 mm3) that is molded within a secondary material to form the compact tension geometry. A generalized equation describing the Mode I stress intensity was developed for the specimen using the solutions from a finite element model that was defined over permissible crack lengths, variations in specimen geometry, and a range in elastic properties of the inset and mold materials. A validation of the generalized equation was performed using estimates for the fracture toughness of a commercial dental composite via the “inset CT” specimen and the standard geometry defined by ASTM E399. Results showed that the average fracture toughness obtained from the new specimen (1.23 ± 0.02 MPa•m0.5) was within 2% of that from the standard. Applications of the inset CT specimen are presented for experimental evaluations on the crack growth resistance of dental enamel and root dentin, including their fracture resistance curves. Potential errors in adopting this specimen are then discussed, including the effects of debonding between the inset and molding material on the estimated stress intensity distribution. Results of the investigation show that the inset CT specimen offers a viable approach for studying the fracture behavior of small volumes of structural materials. PMID:24268892

Users Manual for the Federal Aviation Administration Research and Development Electromagnetic Database (FRED) For Windows: Version 2.0

DOT National Transportation Integrated Search

1998-02-01

This document provides instructional guidelines to users of the Federal Aviation Administration (FAA) Research and Development Electromagnetic Database (FRED) Version 2.0. Instructions are provided on how to access FRED from a compact disk (CD) and h...

How to Program the Principal's Office for the Computer Age.

ERIC Educational Resources Information Center

Frankel, Steven

1983-01-01

Explains why principals' offices need computers and discusses the characteristics of inexpensive personal business computers, including their operating systems, disk drives, memory, and compactness. Reviews software available for word processing, accounting, database management, and communications, and compares the Kaypro II, Morrow, and Osborne I…

Library Instruction and Online Database Searching.

ERIC Educational Resources Information Center

Mercado, Heidi

1999-01-01

Reviews changes in online database searching in academic libraries. Topics include librarians conducting all searches; the advent of end-user searching and the need for user instruction; compact disk technology; online public catalogs; the Internet; full text databases; electronic information literacy; user education and the remote library user;…

Collection Management: Electronically-Delivered Information.

ERIC Educational Resources Information Center

Trawick, Theresa C.; And Others

Issues in the management of library collections of electronically delivered information are discussed, focusing on the library at Troy State University (Alabama). Because of the library's selective depository status, expensive compact disk-read only memory (CD-ROM) products are received, which the library could not normally afford. At the Troy…

Sulphur monoxide exposes a potential molecular disk wind from the planet-hosting disk around HD 100546

NASA Astrophysics Data System (ADS)

Booth, Alice S.; Walsh, Catherine; Kama, Mihkel; Loomis, Ryan A.; Maud, Luke T.; Juhász, Attila

2018-03-01

Sulphur-bearing volatiles are observed to be significantly depleted in interstellar and circumstellar regions. This missing sulphur is postulated to be mostly locked up in refractory form. With ALMA we have detected sulphur monoxide (SO), a known shock tracer, in the HD 100546 protoplanetary disk. Two rotational transitions: J = 77-66 (301.286 GHz) and J = 78-67 (304.078 GHz) are detected in their respective integrated intensity maps. The stacking of these transitions results in a clear 5σ detection in the stacked line profile. The emission is compact but is spectrally resolved and the line profile has two components. One component peaks at the source velocity and the other is blue-shifted by 5 km s-1. The kinematics and spatial distribution of the SO emission are not consistent with that expected from a purely Keplerian disk. We detect additional blue-shifted emission that we attribute to a disk wind. The disk component was simulated using LIME and a physical disk structure. The disk emission is asymmetric and best fit by a wedge of emission in the north-east region of the disk coincident with a "hot-spot" observed in the CO J = 3-2 line. The favoured hypothesis is that a possible inner disk warp (seen in CO emission) directly exposes the north-east side of the disk to heating by the central star, creating locally the conditions to launch a disk wind. Chemical models of a disk wind will help to elucidate why the wind is particularly highlighted in SO emission and whether a refractory source of sulphur is needed. An alternative explanation is that the SO is tracing an accretion shock from a circumplanetary disk associated with the proposed protoplanet embedded in the disk at 50 au. We also report a non-detection of SO in the protoplanetary disk around HD 97048.

Tidal tearing of circumstellar disks in Be/X-ray and gamma-ray binaries

NASA Astrophysics Data System (ADS)

Okazaki, Atsuo T.

2017-11-01

About one half of high-mass X-ray binaries host a Be star [an OB star with a viscous decretion (slowly outflowing) disk]. These Be/X-ray binaries exhibit two types of X-ray outbursts (Stella et al. 1986), normal X-ray outbursts (L X~1036-37 erg s-1) and occasional giant X-ray outbursts (L X > 1037 erg s-1). The origin of giant X-ray outbursts is unknown. On the other hand, a half of gamma-ray binaries have a Be star as the optical counterpart. One of these systems [LS I +61 303 (P orb = 26.5 d)] shows the superorbital (1,667 d) modulation in radio through X-ray bands. No consensus has been obtained for its origin. In this paper, we study a possibility that both phenomena are caused by a long-term, cyclic evolution of a highly misaligned Be disk under the influence of a compact object, by performing 3D hydrodynamic simulations. We find that the Be disk cyclically evolves in mildly eccentric, short-period systems. Each cycle consists of the following stages: 1) As the Be disk grows with time, the initially circular disk becomes eccentric by the Kozai-Lidov mechanism. 2) At some point, the disk is tidally torn off near the base and starts precession. 3) Due to precession, a gap opens between the disk base and mass ejection region, which allows the formation of a new disk in the stellar equatorial plane (see Figure 1). 4) The newly formed disk finally replaces the precessing old disk. Such a cyclic disk evolution has interesting implications for the long-term behavior of high energy emission in Be/X-ray and gamma-ray binaries.

Explosive Compations of Intermetallic-Forming Powder Mixtures for Fabricating Structural Energetic Materials

NASA Astrophysics Data System (ADS)

Du, S. W.; Aydelotte, B.; Fondse, D.; Wei, C.-T.; Jiang, F.; Herbold, E.; Vecchio, K.; Meyers, M. A.; Thadhani, N. N.

2009-12-01

A double-tube implosion geometry is used to explosively shock consolidate intermetallic-forming Ni-Al, Ta-Al, Nb-Al, Mo-Al and W-Al powder mixtures for fabricating bulk structural energetic materials, with mechanical strength and ability to undergo impact-initiated exothermic reactions. The compacts are characterized based on uniformity of micro structure and degree of densification. Mechanical properties of the compacts are characterized over the strain-rate range of 10-3 to 104 s-1. The impact reactivity is determined using rod-on-anvil experiments, in which disk-shaped compacts mounted on a copper projectile, are impacted against a steel anvil in using a 7.62 mm gas gun. The impact reactivity of the various explosively-consolidated reactive powder mixture compacts is correlated with overall kinetic energy and impact stress to determine their influence on threshold for reaction initiation. The characteristics of the various compacts, their mechanical properties and impact-initiated chemical reactivity will be described in this paper.

Rapid variability, dying pulse trains and black holes

NASA Technical Reports Server (NTRS)

Stoeger, W. R.

1980-01-01

After reviewing the general model and arguments by which rapid temporal variability and quasi-periodicities are considered indicative of a compact source's possible black hole character, the paper presents a scenario for 'dying pulse trains'. These originate inside the inner edge of accretion disks encircling black holes from accreting flares or other self-luminous entities executing their final few revolutions before reaching the event horizon. Confirmed detection of such phenomena with time scales in the range 0.01 (M/solar mass) to 0.5 (M/solar mass)ms, where M is the mass of the compact source, would provide much better support for its black hole candidacy. Variability on time-scales larger than this by itself places few constraints on the nature of the compact object.

Specimen preparation for x-ray fluorescence analysis of solutions

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

Eksperiandova, L.P.; Spolnik, Z.M.; Blank, A.B.

1995-12-31

Specimens for x-ray fluorescence analysis (XRFA) were prepared by adding dry gelatine (10%) to the analysis solution, homogenizing the mixture and cooling for 20 minutes. Thus, a compact resilient mass could be formed with the required shape and size; the roughness of the surface was determined by the roughness of the surface on which the specimen was formed, much the same as highly polished. Various calibration methods can be applied in the XRFA of a variety of materials if such specimens are used. 12 refs., 1 fig., 2 tabs.

Constant load and constant volume response of municipal solid waste in simple shear.

PubMed

Zekkos, Dimitrios; Fei, Xunchang

2017-05-01

Constant load and constant volume simple shear testing was conducted on relatively fresh municipal solid waste (MSW) from two landfills in the United States, one in Michigan and a second in Texas, at respective natural moisture content below field capacity. The results were assessed in terms of two failure strain criteria, at 10% and 30% shear strain, and two interpretations of effective friction angle. Overall, friction angle obtained assuming that the failure plane is horizontal and at 10% shear strain resulted in a conservative estimation of shear strength of MSW. Comparisons between constant volume and constant load simple shear testing results indicated significant differences in the shear response of MSW with the shear resistance in constant volume being lower than the shear resistance in constant load. The majority of specimens were nearly uncompacted during specimen preparation to reproduce the state of MSW in bioreactor landfills or in uncontrolled waste dumps. The specimens had identical percentage of <20mm material but the type of <20mm material was different. The <20mm fraction from Texas was finer and of high plasticity. MSW from Texas was overall weaker in both constant load and constant volume conditions compared to Michigan waste. The results of these tests suggest the possibility of significantly lower shear strength of MSW in bioreactor landfills where waste is placed with low compaction effort and constant volume, i.e., "undrained", conditions may occur. Compacted MSW specimens resulted in shear strength parameters that are higher than uncompacted specimens and closer to values reported in the literature. However, the normalized undrained shear strength in simple shear for uncompacted and compacted MSW was still higher than the normalized undrained shear strength reported in the literature for clayey and silty soils. Copyright © 2016 Elsevier Ltd. All rights reserved.

General-relativistic rotation: Self-gravitating fluid tori in motion around black holes

NASA Astrophysics Data System (ADS)

Karkowski, Janusz; Kulczycki, Wojciech; Mach, Patryk; Malec, Edward; Odrzywołek, Andrzej; Piróg, Michał

2018-05-01

We obtain from the first principles a general-relativistic Keplerian rotation law for self-gravitating disks around spinning black holes. This is an extension of a former rotation law that was designed mainly for toroids around spinless black holes. We integrate numerically axial stationary Einstein equations with self-gravitating disks around spinless or spinning black holes; that includes the first ever integration of the Keplerian selfgravitating tori. This construction can be used for the description of tight black hole-torus systems produced during coalescences of two neutron stars or modelling of compact active galactic nuclei.

Reference System of DNA and Protein Sequences on CD-ROM

NASA Astrophysics Data System (ADS)

Nasu, Hisanori; Ito, Toshiaki

DNASIS-DBREF31 is a database for DNA and Protein sequences in the form of optical Compact Disk (CD) ROM, developed and commercialized by Hitachi Software Engineering Co., Ltd. Both nucleic acid base sequences and protein amino acid sequences can be retrieved from a single CD-ROM. Existing database is offered in the form of on-line service, floppy disks, or magnetic tape, all of which have some problems or other, such as usability or storage capacity. DNASIS-DBREF31 newly adopt a CD-ROM as a database device to realize a mass storage and personal use of the database.

Compact Packaging of Photonic Millimeter-Wave Receiver

NASA Technical Reports Server (NTRS)

Nguyen, Hung; Pouch, John; Miranda, Felix; Levi, Anthony F.

2007-01-01

A carrier structure made from a single silicon substrate is the basis of a compact, lightweight, relatively inexpensive package that holds the main optical/electronic coupling components of a photonic millimeter-wave receiver based on a lithium niobate resonator disk. The design of the package is simple and provides for precise relative placement of optical components, eliminating the need for complex, bulky positioning mechanisms like those commonly used to align optical components to optimize focus and coupling. Although a prototype of the package was fabricated as a discrete unit, the design is amenable to integration of the package into a larger photonic and/or electronic receiver system. The components (see figure) include a lithium niobate optical resonator disk of 5-mm diameter and .200- m thickness, positioned adjacent to a millimeter- wave resonator electrode. Other components include input and output coupling prisms and input and output optical fibers tipped with ball lenses for focusing and collimation, respectively. Laser light is introduced via the input optical fiber and focused into the input coupling prism. The input coupling prism is positioned near (but not in contact with) the resonator disk so that by means of evanescent-wave coupling, the input laser light in the prism gives rise to laser light propagating circumferentially in guided modes in the resonator disk. Similarly, a portion of the circumferentially propagating optical power is extracted from the disk by evanescent-wave coupling from the disk to the output coupling prism, from whence the light passes through the collimating ball lens into the output optical fiber. The lens-tipped optical fibers must be positioned at a specified focal distance from the prisms. The optical fibers and the prisms must be correctly positioned relative to the resonator disk and must be oriented to obtain the angle of incidence (55 in the prototype) required for evanescent-wave coupling of light into and out of the desired guided modes in the resonator disk. To satisfy all these requirements, precise alignment features are formed in the silicon substrate by use of a conventional wet-etching process. These features include a 5-mm-diameter, 50- m-deep cavity that holds the disk; two trapezoidal-cross-section recesses for the prisms; and two grooves that hold the optical fibers at the correct positions and angles relative to the prisms and disk. The fiber grooves contain abrupt tapers, near the prisms, that serve as hard stops for positioning the lenses at the focal distance from the prisms. There are also two grooves for prismadjusting rods. The design provides a little slack in the prism recesses for adjusting the positions of the prisms by means of these rods to optimize the optical coupling.

Metallic transfer between metals in sliding contact examined by auger emission spectroscopy

NASA Technical Reports Server (NTRS)

Pepper, S. V.

1972-01-01

Metallic transfer between polycrystalline metals in sliding contact was examined. Hemispherical riders of iron, nickel, and cobalt were slid on tungsten, tantalum, niobium, and molybdenum disks in ultrahigh vacuum. Auger emission spectroscopy was used to monitor the elemental composition of the disk surfaces. Iron, nickel, and cobalt transferred to tungsten, whereas only cobalt transferred to tantalum, niobium, and molybdenum. The results of this investigation are discussed in terms of the cohesive energy and strain hardening characteristics of the specimen materials.

Optimization of test parameters for quantitative stress measurements using the miniaturized disk-bend test

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

Meyers, D.E.; Chen, F.C.; Zhang, J.

A recently-developed miniaturized disk-bend test (MDBT) has been successfully used to evaluate the mechanical properties of a variety of materials, using specimens 3 mm in diameter. The load is applied either by a solid ball (the ball-on ring (BOR) mode), or by a hollow cylinder (the ring-on-ring (ROR) mode). They authors have reproduced the yield stresses of ordered intermetallic compounds and the fracture toughness of several ceramics using analytical solutions to the equations of elasticity theory. Despite this success there are several curious features involved in the analysis of data; for example, in previous tests conducted in the BOR modemore » correct values of the yield stress were obtained using the equations appropriate to clamped specimens, whether or not hey were actually clamped in the test fixture. They show that this is ubiquitous to tests in the BOR mode, and does not arise because of frictional constraints at the supporting ring. They have also completed a thorough evaluation of testing in the ROR mode, in which the yield stresses of cold-rolled or annealed AISI type 302 stainless steel were measured using various combinations of specimen thickness and radii of the loading and supporting rings, and compared to those of tensile specimens machined from the same material. The most accurate and reproducible measurements of the yield strength were obtained for specific combinations of specimen thickness and geometry of the apparatus.« less

Small-Scale Thermal Violence Cook Off Test

NASA Astrophysics Data System (ADS)

Cook, Malcolm; Curtis, John; Stennett, Christopher

2015-06-01

The Small-Scale thermal Violence Test (SSVT) is designed to quantify the violence (explosiveness) of test materials by means of observing the velocity history of a metal burst disk that forms one end of a strong thick-walled cylindrical test vehicle. A copper heating block is placed to the rear of, but in contact with, the sample and provides sealing. The difference in thermal conductivity between copper and steel is sufficient that thermal runaway is induced near to the explosive / copper interface in an unlagged test. A series of experiments has been made, in which explosive specimens were confined and heated to explosion. A high-accuracy velocity measurement system was used to record the motion of the bursting disk. These experiments have shown that the early-time motion of the bursting disk corresponds qualitatively to the onset of thermal explosion and growth of reaction within the explosive specimens. However, the velocity history traces are more complex than had been anticipated. In particular, unexplained shoulders were observed in the Phase-Doppler Velocimeter (PDV) data. Some preliminary modelling studies have been carried out in order to shed light on the complex shapes of the projectile velocity histories.

A close look into the carbon disk at the core of the planetary nebula CPD-56°8032

NASA Astrophysics Data System (ADS)

Chesneau, O.; Collioud, A.; De Marco, O.; Wolf, S.; Lagadec, E.; Zijlstra, A. A.; Rothkopf, A.; Acker, A.; Clayton, G. C.; Lopez, B.

2006-09-01

Aims.We present high spatial resolution observations of the dusty core of the Planetary Nebula with Wolf-Rayet central star CPD-56°8032, for which indications of a compact disk have been found by HST/SITS observations. Methods: .These observations were taken with the mid-infrared interferometer VLTI/MIDI in imaging mode providing a typical 300 mas resolution and in interferometric mode using UT2-UT3 47m baseline providing a typical spatial resolution of 20 mas. We also made use of unpublished HST/ACS images in the F435W and F606W filters. Results: .The visible HST images exhibit a complex multilobal geometry dominated by faint lobes. The farthest structures are located at 7 arcsec from the star. The mid-IR environment of CPD-56°8032 is dominated by a compact source, barely resolved by a single UT telescope in a 8.7 μm filter (Δ λ=1.6~μm, contaminated by PAH emission). The infrared core is almost fully resolved with the three 40-45 m projected baselines ranging from -5° to 51° but smooth oscillating fringes at low level have been detected in spectrally dispersed visibilities. This clear signal is interpreted in terms of a ring structure which would define the bright inner rim of the equatorial disk. Geometric models allowed us to derive the main geometrical parameters of the disk. For instance, a reasonably good fit is reached with an achromatic and elliptical truncated Gaussian with a radius of 97±11 AU, an inclination of 28±7° and a PA for the major axis at 345° ±7°. Furthermore, we performed some radiative transfer modeling aimed at further constraining the geometry and mass content of the disk, by taking into account the MIDI dispersed visibilities, spectra, and the large aperture SED of the source. These models show that the disk is mostly optically thin in the N band and highly flared. As a consequence of the complex flux distribution, an edge-on inclination is not excluded by the data.

Get Ready for Generation Next.

ERIC Educational Resources Information Center

Wellner, Alison

1999-01-01

"Generation Next" are the 68 million people born between 1977 and 1994. They are the first generation that has grown up with such technologies as computers, the Internet, compact disks, and microwaves and they have more education than previous generations. They will have an effect on trainers and training methods in the workplace. (JOW)

The American Indian: A Multimedia Encyclopedia.

ERIC Educational Resources Information Center

Carter, Christina E.

1993-01-01

Reviews "The American Indian: A Multimedia Encyclopedia," Version 1.0 (New York, Facts on File, Inc., 1993). This electronic product (compact disk) presents a great amount of material on American Indians from various formats, but its effectiveness is limited by the dated nature of some materials. Software design and searching features are…

Multimedia in Education: Summary Chapter.

ERIC Educational Resources Information Center

Hooper, Kristina

1986-01-01

This summary of issues addressed at the conference identifies 10 important themes: (1) the nature of interactivity, and whether linear presentations are obsolete; (2) what can be done with all the imagery made possible with videodisks and the sounds enabled by compact disks, and whether any of this is really new; (3) whether emotional…

Teach with Databases: Toxics Release Inventory. [Multimedia].

ERIC Educational Resources Information Center

Barracato, Jay; Spooner, Barbara

This curriculum unit provides students with real world applications of science as it pertains to toxic releases into the environment. This boxed package contains the Toxics Release Inventory (TRI) Teacher's Guide, TRI Database Basics guide, comprehensive TRI compact disk with user's guide, "Getting Started: A Guide to Bringing Environmental…

Reinventing Schools: The Technology Is Now!

ERIC Educational Resources Information Center

Ellmore, Douglas A., Sr.; Olson, Steve E.; Smith, Phillip M.

1995-01-01

Today's children have grown up immersed in a world of computers and other information technologies. They play video games; they listen to music on digital compact disks; they help their families program the computerized controls of videocassette players. With all of the exciting innovations in computer technology, children have the opportunity to…

Split-orientation-modulated plasmon coupling in disk/sector dimers

NASA Astrophysics Data System (ADS)

Zhu, Xupeng; Chen, Yiqin; Shi, Huimin; Zhang, Shi; Liu, Quanhui; Duan, Huigao

2017-06-01

The coupled asymmetric plasmonic nanostructures allow more compact nanophotonics integration and easier optical control in practical applications, such as directional scattering and near-field control. Here, we carried out a systematic and in-depth study on the plasmonic coupling of an asymmetric gold disk/sector dimer, and investigated the light-matter interaction in such an asymmetric coupled complex nanostructures. The results demonstrated that the positions and the intensity of plasmon resonance peak as well as the spatial distribution of electric fields around the surface in the coupled disk/sector dimer can be tuned by changing the azimuth angle of the gold sector. Based on Simpson-Peterson approximation, we proposed a model to understand the obtained plasmon properties of asymmetric coupled disk/sector dimers by introducing an offset parameter between the geometry center and dipole center of the sector. The experimental results agree well with the simulations. Our study provides an insight to tune the plasmon coupling behavior via adjusting the plasmon dipole center position in coupling systems.

Third-dimension information retrieval from a single convergent-beam transmission electron diffraction pattern using an artificial neural network

NASA Astrophysics Data System (ADS)

Pennington, Robert S.; Van den Broek, Wouter; Koch, Christoph T.

2014-05-01

We have reconstructed third-dimension specimen information from convergent-beam electron diffraction (CBED) patterns simulated using the stacked-Bloch-wave method. By reformulating the stacked-Bloch-wave formalism as an artificial neural network and optimizing with resilient back propagation, we demonstrate specimen orientation reconstructions with depth resolutions down to 5 nm. To show our algorithm's ability to analyze realistic data, we also discuss and demonstrate our algorithm reconstructing from noisy data and using a limited number of CBED disks. Applicability of this reconstruction algorithm to other specimen parameters is discussed.

Procedure for Uranium-Molybdenum Density Measurements and Porosity Determination

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

Prabhakaran, Ramprashad; Devaraj, Arun; Joshi, Vineet V.

2016-08-13

The purpose of this document is to provide guidelines for preparing uranium-molybdenum (U-Mo) specimens, performing density measurements, and computing sample porosity. Typical specimens (solids) will be sheared to small rectangular foils, disks, or pieces of metal. A mass balance, solid density determination kit, and a liquid of known density will be used to determine the density of U-Mo specimens using the Archimedes principle. A standard test weight of known density would be used to verify proper operation of the system. By measuring the density of a U-Mo sample, it is possible to determine its porosity.

The Tensile Properties of Advanced Nickel-Base Disk Superalloys During Quenching Heat Treatments

NASA Technical Reports Server (NTRS)

Gabb, Timothy P.; Gayda, John; Kantzos, Pete T.; Biles, Tiffany; Konkel, William

2001-01-01

There is a need to increase the temperature capabilities of superalloy turbine disks. This would allow full utilization of higher temperature combustor and airfoil concepts under development. One approach to meet this goal is to modify the processing and chemistry of advanced alloys, while preserving the ability to use rapid cooling supersolvus heat treatments to achieve coarse grain, fine gamma prime microstructures. An important step in this effort is to understand the key high temperature tensile properties of advanced alloys as they exist during supersolvus heat treatments. This could help in projecting cracking tendencies of disks during quenches from supersolvus heat treatments. The objective of this study was to examine the tensile properties of two advanced disk superalloys during simulated quenching heat treatments. Specimens were cooled from the solution heat treatment temperatures at controlled rates, interrupted, and immediately tensile tested at various temperatures. The responses and failure modes were compared and related to the quench cracking tendencies of disk forgings.

Microbial Characterization of Solid-Wastes Treated with Heat Melt Compaction Technology

NASA Technical Reports Server (NTRS)

Strayer, Richard F.; Hummerick, Mary E.; Richards, Jeffrey T.; McCoy, LaShelle E.; Roberts, Michael S.; Wheeler, Raymond M.

2011-01-01

The research purpose of the project was to determine the fate of microorganisms in space-generated solid wastes after processing by a Heat Melt Compactor (HMC), which is a candidate solid waste treatment technology. Five HMC product disks were generated at Ames Research Center (ARC), Waste Management Systems element. The feed for two was simulated space-generated trash and feed for three was Volume F compartment wet waste returned on STS 130. Conventional microbiological methods were used to detect and enumerate microorganisms in HMC disks and in surface swab samples of HMC hardware before and after operation. Also, biological indicator test strips were added to the STS trash prior to compaction to test if HMC processing conditions, 150 C for approx 3 hr and dehydration, were sufficient to eliminate the test bacteria on the strips. During sample acquisition at KSC, the HMC disk surfaces were sanitized with 70% alcohol to prevent contamination of disk interiors. Results from microbiological assays indicated that numbers of microbes were greatly reduced but not eliminated by the 70% alcohol. Ten 1.25 cm diameter cores were aseptically cut from each disk to sample the disk interior. The core material was run through the microbial characterization analyses after dispersal in sterile diluent. Low counts of viable bacteria (5 to 50 per core) were found but total direct counts were 6 to 8 orders of magnitude greater. These results indicate that the HMC operating conditions might not be sufficient for complete waste sterilization, but the vast majority of microbes present in the wastes were dead or non-cultivable after HMC treatment. The results obtained from analyses of the commercial spore test strips that had been added fo the wastes prior to HMC operation further indicated that the HMC was sterilizing the wastes. Nearly all strips were recovered from the HMC disks and all of these were negative for spore growth when run through the manufacturer's protocol. The 10(exp 6) or so spores impregnated into the strips were no longer viable. Control test strips, i.e., not exposed to the HMC conditions, were all strongly positive. All isolates from the cultivable counts were identified, leading to one concern: several were identified as Staphylococcus aureus, a human pathogen. The project reported here provides microbial characterization support to the Waste Management Systems element of the Life Support and Habitation Systems program.

Contact thermal shock test of ceramics

NASA Technical Reports Server (NTRS)

Rogers, W. P.; Emery, A. F.

1992-01-01

A novel quantitative thermal shock test of ceramics is described. The technique employs contact between a metal-cooling rod and hot disk-shaped specimen. In contrast with traditional techniques, the well-defined thermal boundary condition allows for accurate analyses of heat transfer, stress, and fracture. Uniform equibiaxial tensile stresses are induced in the center of the test specimen. Transient specimen temperature and acoustic emission are monitored continuously during the thermal stress cycle. The technique is demonstrated with soda-lime glass specimens. Experimental results are compared with theoretical predictions based on a finite-element method thermal stress analysis combined with a statistical model of fracture. Material strength parameters are determined using concentric ring flexure tests. Good agreement is found between experimental results and theoretical predictions of failure probability as a function of time and initial specimen temperature.

Fast and Slow Precession of Gaseous Debris Disks around Planet-accreting White Dwarfs

NASA Astrophysics Data System (ADS)

Miranda, Ryan; Rafikov, Roman R.

2018-04-01

Spectroscopic observations of some metal-rich white dwarfs (WDs), believed to be polluted by planetary material, reveal the presence of compact gaseous metallic disks orbiting them. The observed variability of asymmetric, double-peaked emission-line profiles in about half of such systems could be interpreted as the signature of precession of an eccentric gaseous debris disk. The variability timescales—from decades down to 1.4 year (recently inferred for the debris disk around HE 1349–2305)—are in rough agreement with the rate of general relativistic (GR) precession in the test-particle limit. However, it has not been demonstrated that this mechanism can drive such a fast, coherent precession of a radially extended (out to 1 {R}ȯ ) gaseous disk mediated by internal stresses (pressure). Here, we use the linear theory of eccentricity evolution in hydrodynamic disks to determine several key properties of eccentric modes in gaseous debris disks around WDs. We find a critical dependence of both the precession period and radial eccentricity distribution of the modes on the inner disk radius, r in. For small inner radii, {r}in}≲ (0.2{--}0.4) {R}ȯ , the modes are GR-driven, with periods of ≈1–10 year. For {r}in}≳ (0.2{--}0.4) {R}ȯ , the modes are pressure dominated, with periods of ≈3–20 year. Correspondence between the variability periods and inferred inner radii of the observed disks is in general agreement with this trend. In particular, the short period of HE 1349–2305 is consistent with its small r in. Circum-WD debris disks may thus serve as natural laboratories for studying the evolution of eccentric gaseous disks.

First Detection of Methanol in a Class O Protostellar Disk

NASA Technical Reports Server (NTRS)

Velusamy, T.; Langer, William D.; Goldsmith, Paul F.

2000-01-01

We report the detection of emission from methanol in a compact source coincident with the position of the L1157 infrared source, which we attribute to molecules in the disk surrounding this young, Class O protostellar object. In addition, we identify a spectral feature in the outflow corresponding to an ethanol transition. Using the Caltech Owens Valley Millimeter Array with a synthesized beam size of 2", we detect spatially unresolved methanol in the 2(sub k) - 1(sub k) transitions at 3mm, which is coincident in position with the peak of the continuum emission. The gas phase methanol could be located in the central region (< 100 AU radius) of a flat disk, or in an extended heated surface layer (approx. 200 AU radius) of a flared disk. The fractional abundance of methanol X(CH3OH) is approx. 2 x l0(exp -8) in the flat disk model, and 3 x l0(exp -7) for the flared disk. The fractional abundance is small in the disk as a whole, but considerably larger in the warm portions. This difference indicates that substantial chemical processing probably takes place in the disk via depletion and desorption. The methanol desorbed from the grains in the warm surface layers returns to the icy grain mantles in the cooler interior of the disk, where it is available to become part of the composition of solar system-like bodies, such as comets, formed in the outer circumstellar region. This first millimeter-wavelength detection of a complex organic molecule in a young protostellar disk has implications for disk structure and chemical evolution and for potential use as a temperature probe. The research of TV and WL was conducted at the Jet Propulsion Laboratory, California Institute of Technology with support from the National Aeronautics and Space Administration.

Properties and Corrosion Performance of Self-reinforced Composite PEEK for Proposed Use as a Modular Taper Gasket.

PubMed

Ouellette, Eric S; Gilbert, Jeremy L

2016-11-01

Fretting corrosion in medical alloys is a persistent problem, and the need for biomaterials that can effectively suppress mechanically assisted crevice corrosion in modular taper junctions or otherwise insulate metal-on-metal interfaces in mechanically demanding environments is as yet unmet. The purpose of this study is to characterize a novel material, self-reinforced composite polyetheretherketone (SRC-PEEK) and to evaluate its ability to inhibit fretting corrosion in a pin-on-disk metal-on-metal interface test. SRC-PEEK was fabricated by hot compaction of in-house-made PEEK fibers by compacting uniaxial layups at 344°C under a load of 18,000 N for 10 minutes. SRC-PEEK, bulk isotropic PEEK, and the in-house-made PEEK fibers were analyzed for thermal transitions (T g , T m ) through differential scanning calorimetry, crystallinity, crystal size, crystalline orientation (Hermanns orientation parameter) through wide-angle x-ray scattering, and modulus, tensile strength, yield stress, and strain to failure through monotonic tensile testing. SRC-insulated pin-on-disk samples were compared with metal-on-metal control samples in pin-on-disk fretting corrosion experiments using fretting current and fretting mechanics measurements. Fifty-micron cyclic motion at 2.5 Hz was applied to the interface, first over a range of loads (0.5-35 N) while held at -0.05 V versus Ag/AgCl and then over a range of voltages (-0.5 to 0.5 V) at a constant contact stress of 73 ± 19 MPa for SRC-PEEK and 209 ± 41 MPa for metal-on-metal, which were different for each group as a result of changes in true contact area due to variations in modulus between sample groups. Pins, disks, and SRC samples were imaged for damage (on alloy and SRC surfaces) and evidence of corrosion (on alloy pin and disk surfaces). SRC specimens were analyzed for traces of alloy transferred to the surface using energy dispersive spectroscopy after pin-on-disk testing. SRC-PEEK showed improved mechanical properties to bulk PEEK (modulus = 5.0 ± 0.3 GPa, 2.8 ± 0.1 GPa, respectively, p < 0.001) and higher crystallinity to bulk PEEK (44.2% ± 3%, 39.5% ± 0.5%, respectively, p = 0.039), but had comparable crystalline orientation as compared with the initial PEEK fibers. SRC-PEEK reduced fretting currents compared with metal-on-metal controls by two to three orders of magnitude in both variable load (4.0E-5 ± 3.8E-5 μA versus 2.9E-3 ± 7.1E-4 μA, respectively, p = 0.018) and variable potential (7.5E-6 ± 4.7E-6 μA versus 5.3E-3 ± 1.4E-3 μA, respectively, p = 0.022) fretting corrosion testing. Minimal damage was observed on surfaces insulated with SRC-PEEK, whereas control surfaces showed considerable fretting corrosion damage and metal transfer. The SRC-PEEK gaskets in this study demonstrated higher crystallinity and crystalline orientation and improved monotonic tensile properties compared with bulk PEEK with the ability to effectively insulate Ti6Al4V and CoCrMo alloy surfaces and prevent the initiation of fretting corrosion under high contact-stress conditions. This novel SRC-PEEK material may offer potential as a thin film gasket material for modular tapers. Pending further in vitro and in vivo analyses, this approach may be able to preserve the advantages of modular junctions for surgeons while potentially limiting the downside risks associated with mechanically assisted crevice corrosion.

Stability and Evolution of Supernova Fallback Disks

NASA Astrophysics Data System (ADS)

Menou, Kristen; Perna, Rosalba; Hernquist, Lars

2001-10-01

We show that thin accretion disks made of carbon or oxygen are subject to the same thermal ionization instability as hydrogen and helium disks. We argue that the instability applies to disks of any metal content. The relevance of the instability to supernova fallback disks probably means that their power-law evolution breaks down when they first become neutral. We construct simple analytical models for the viscous evolution of fallback disks to show that it is possible for these disks to become neutral when they are still young (ages of a few 103 to 104 yr), compact in size (a few 109 to 1011 cm) and generally accreting at sub-Eddington rates (M~a few 1014-1018 g s-1). Based on recent results on the nature of viscosity in the disks of close binaries, we argue that this time may also correspond to the end of the disk activity period. Indeed, in the absence of a significant source of viscosity in the neutral phase, the entire disk will likely turn to dust and become passive. We discuss various applications of the evolutionary model, including anomalous X-ray pulsars and young radio pulsars. Our analysis indicates that metal-rich fallback disks around newly born neutron stars and black holes become neutral generally inside the tidal truncation radius (Roche limit) for planets at ~1011 cm. Consequently, the efficiency of the planetary formation process in this context will mostly depend on the ability of the resulting disk of rocks to spread via collisions beyond the Roche limit. It appears easier for the merger product of a doubly degenerate binary, whether it is a massive white dwarf or a neutron star, to harbor planets because its remnant disk has a rather large initial angular momentum, which allows it to spread beyond the Roche limit before becoming neutral. The early super-Eddington phase of accretion is a source of uncertainty for the disk evolution models presented here.

Formation and Destruction of Jets in X-ray Binaries

NASA Technical Reports Server (NTRS)

Kylafix, N. D.; Contopoulos, I.; Kazanas, D.; Christodoulou, D. M.

2011-01-01

Context. Neutron-star and black-hole X-ray binaries (XRBs) exhibit radio jets, whose properties depend on the X-ray spectral state e.nd history of the source. In particular, black-hole XRBs emit compact, 8teady radio jets when they are in the so-called hard state. These jets become eruptive as the sources move toward the soft state, disappear in the soft state, and then re-appear when the sources return to the hard state. The jets from neutron-star X-ray binaries are typically weaker radio emitters than the black-hole ones at the same X-ray luminosity and in some cases radio emission is detected in the soft state. Aims. Significant phenomenology has been developed to describe the spectral states of neutron-star and black-hole XRBs, and there is general agreement about the type of the accretion disk around the compact object in the various spectral states. We investigate whether the phenomenology describing the X-ray emission on one hand and the jet appearance and disappearance on the other can be put together in a consistent physical picture. Methods. We consider the so-called Poynting-Robertson cosmic battery (PRCB), which has been shown to explain in a natural way the formation of magnetic fields in the disks of AGNs and the ejection of jets. We investigate whether the PRCB can also explain the [ormation, destruction, and variability or jets in XRBs. Results. We find excellent agreement between the conditions under which the PRCB is efficient (i.e., the type of the accretion disk) and the emission or destruction of the r.adio jet. Conclusions. The disk-jet connection in XRBs can be explained in a natural way using the PRCB.

The nebula around the post-AGB star 89 Herculis

NASA Astrophysics Data System (ADS)

Bujarrabal, V.; van Winckel, H.; Neri, R.; Alcolea, J.; Castro-Carrizo, A.; Deroo, P.

2007-06-01

Aims:We aim to study the structure of the nebula around the post-AGB, binary star 89 Her. The presence of a rotating disk around this star had been proposed but not been yet confirmed by observations. Methods: We present high-resolution PdBI maps of CO J=2-1 and 1-0. Properties of the nebula are directly derived from the data and model fitting. We also present N-band interferometric data on the extent of the hot dust emission, obtained with the VLTI. Results: Two nebular components are found: (a) an extended hour-glass-like structure, with expansion velocities of 7 km s-1 and a total mass 3× 10-3 M{⊙}, and (b) an unresolved very compact component, smaller than 0.4 arcsec and with a low total velocity dispersion of 5 km s-1. We cannot determine the velocity field in the compact component, but we argue that it can hardly be in expansion, since this would require too recent and too sudden an ejection of mass. On the other hand, assuming that this component is a Keplerian disk, we derive disk properties that are compatible with expectations for such a structure; in particular, the size of the rotating gas disk should be very similar to the extent of the hot dust component from our VLTI data. Assuming that the equator of the extended nebula coincides with the binary orbital plane, we provide new results on the companion star mass and orbit. Based on observations carried out with the IRAM Plateau de Bure Interferometer, as well as on observations of the Belgian Guaranteed time on VISA (ESO). IRAM is supported by INSU/CNRS (France), MPG (Germany) and IGN (Spain).

VLA Imaging of Protoplanetary Environments

NASA Technical Reports Server (NTRS)

Wilner, David J.

2004-01-01

We summarize the major accomplishments of our program to use high angular resolution observations at millimeter wavelengths to probe the structure of protoplanetary disks in nearby regions of star formation. The primary facilities used in this work were the Very Large Array (VLA) of the National Radio Astronomy Observatories (NRAO) located in New Mexico, and the recently upgraded Australia Telescope Compact Array (ATCA), located in Australia (to access sources in the far southern sky). We used these facilities to image thermal emission from dust particles in disks at long millimeter wavelengths, where the emission is optically thin and probes the full disk volume, including the inner regions of planet formation that remain opaque at shorter wavelengths. The best resolution obtained with the VLA is comparable to the size scales of the orbits of giant planets in our Solar System (< 10 AU).

Implosive accretion and outbursts of active galactic nuclei

NASA Technical Reports Server (NTRS)

Lovelace, R. V. E.; Romanova, M. M.; Newman, W. I.

1994-01-01

A model and simulation code have been developed for time-dependent axisymmetric disk accretion onto a compact object including for the first time the influence of an ordered magnetic field. The accretion rate and radiative luminosity of the disk are naturally coupled to the rate of outflow of energy and angular momentum in magnetically driven (+/- z) winds. The magnetic field of the wind is treated in a phenomenological way suggested by self-consistent wind solutions. The radial accretion speed u(r, t) of the disk matter is shown to be the sum of the usual viscous contribution and a magnetic contribution proportional to r(exp 3/2)(B(sub p exp 2))/sigma, where B(sub p)(r,t) is the poloidal field threading the disk and sigma(r,t) is the disk's surface mass density. An enhancement or variation in B(sub p) at a large radial distance leads to the formation of a soliton-like structure in the disk density, temperature, and B-field which propagates implosively inward. The implosion gives a burst in the power output in winds or jets and a simultaneous burst in the disk radiation. The model is pertinent to the formation of discrete fast-moving components in jets observed by very long baseline interferometry. These components appear to originate at times of optical outbursts of the active galactic nucleus.

A study of sound absorption by street canyon boundaries and asphalt rubber concrete pavement

NASA Astrophysics Data System (ADS)

Drysdale, Graeme Robert

A sound field model, based on a classical diffusion equation, is extended to account for sound absorption in a diffusion parameter used to model sound energy in a narrow street canyon. The model accounts for a single sound absorption coefficient, separate accommodation coefficients and a combination of separate absorption and accommodation coefficients from parallel canyon walls. The new expressions are compared to the original formula through numerical simulations to reveal the effect of absorption on sound diffusion. The newly established analytical formulae demonstrate satisfactory agreement with their predecessor under perfect reflection. As well, the influence of the extended diffusion parameter on normalized sound pressure levels in a narrow street canyon is in agreement with experimental data. The diffusion parameters are used to model sound energy density in a street canyon as a function of the sound absorption coefficient of the street canyon walls. The acoustic and material properties of conventional and asphalt rubber concrete (ARC) pavement are also studied to assess how the crumb rubber content influences sound absorption in street canyons. The porosity and absolute permeability of compacted specimens of asphalt rubber concrete are measured and compared to their normal and random incidence sound absorption coefficients as a function of crumb rubber content in the modified binder. Nonlinear trends are found between the sound absorption coefficients, porosity and absolute permeability of the compacted specimens and the percentage of crumb rubber in the modified binders. The cross-sectional areas of the air voids on the surfaces of the compacted specimens are measured using digital image processing techniques and a linear relationship is obtained between the average void area and crumb rubber content. The measured material properties are used to construct an empirical formula relating the average porosity, normal incidence noise reduction coefficients and percentage of crumb rubber in the modified binder of the compacted specimens.

Smearing of mass accretion rate variation by viscous processes in accretion disks in compact binary systems

NASA Astrophysics Data System (ADS)

Ghosh, A.; Chakrabarti, Sandip K.

2016-09-01

Variation of mass supply rate from the companion can be smeared out by viscous processes inside an accretion disk. Hence, by the time the flow reaches the inner edge, the variation in X-rays need not reflect the true variation of the mass supply rate at the outer edge. However, if the viscosity fluctuates around a mean value, one would expect the viscous time scale t_{{visc}} also to spread around a mean value. In high mass X-ray binaries, which are thought to be primarily wind-fed, the size of the viscous Keplerian disk is smaller and thus such a spread could be lower as compared to the low mass X-ray binaries which are primarily fed by Roche lobe overflow. If there is an increasing or decreasing trend in viscosity, the interval between enhanced emission would be modified systematically. In the absence of a detailed knowledge about the variation of mass supply rates at the outer edge, we study ideal circumstances where modulation must take place exactly in orbital time scales, such as when there is an ellipticity in the orbit. We study a few compact binaries using long term All Sky monitor (ASM) data (1.5-12 keV) of Rossi X-ray Timing Explorer (RXTE) and all sky survey data (15-50 keV) of Swift satellites by different methods to look for such smearing effects and to infer what these results can tell us about the viscous processes inside the respective disks. We employ three different methods to seek imprints of periodicity on the X-ray variation and found that in all the cases, the location of the peak in the power density spectra is consistent with the orbital frequencies. Interestingly, in high mass X-ray binaries the peaks are sharp with high rms values, consistent with a small Keplerian disk in a wind fed system. However, in low mass X-ray binaries with larger Keplerian disk component, the peaks are spreaded out with much lower rms values. X-ray reflections, or superhump phenomena which may also cause such X-ray modulations would not be affected by the size of the Keplerian disk component. Our result thus confirms different sizes of Keplerian disks in these two important classes of binaries. If the orbital periods of any binary system is not known, they may be obtained with reasonable accuracy for HMXBs and with lesser accuracy for LMXBs by our method.

Instrumented Pressing of HE and Inert Materials to Study the Effect of Particle Size

NASA Astrophysics Data System (ADS)

Stull, Jamie; Woznick, Caitlin; Deluca, Racci; Patterson, Brain; Thompson, Darla Graff

2017-06-01

It is well known that detonation and mechanical properties of high explosives (HE) depend on density. Computationally it has been shown that specific particle-size distributions will lead to better pressed parts. Theoretically this should improve moderate compaction conditions, uniform density and strength. There are many other powder characteristics that are important such as crystal shape and strength. We are interested to explore the role of HE powder characteristics on compaction properties and pellet integrity. We have used an instrumented compaction instrument to press inert and HE powders such as TATB and HMX, which have very different crystal structures. The force and displacement measurements from the instrumented press provide information on the quality of compaction of the specimen in the form of Heckel plots, etc. We have evaluated the thermal and mechanical integrity of resultant pellets by measuring the coefficient of thermal expansion and the compressive strength and strain at failure. We have employed micro x-ray computed tomography (CT) to characterize the microstructure and to quantify the number, the size, and the location of voids. The lack of binder in these specimens greatly simplifies the microstructure analysis and makes the data more amenable to modeling and interpretation.

Probing the Gaseous Disk of T Tau N with CN 5-4 Lines

NASA Technical Reports Server (NTRS)

Podio, L.; Kamp, I.; Codella, C.; Nisini, B.; Aresu, G.; Brittain, S.; Cabrit, S.; Dougados, C.; Grady, C.; Meijerink, R.;

Miniaturized INtrinsic DISsolution Screening (MINDISS) assay for preformulation.

PubMed

Alsenz, Jochem; Haenel, Elisabeth; Anedda, Aline; Du Castel, Pauline; Cirelli, Giorgio

2016-05-25

This study describes a novel Miniaturized INtrinsic DISsolution Screening (MINDISS) assay for measuring disk intrinsic dissolution rates (DIDR). In MINDISS, compacted mini disks of drugs (2-5mg/disk) are prepared in custom made holders with a surface area of 3mm(2). Disks are immersed, pellet side down, into 0.35ml of appropriate dissolution media per well in 96-well microtiter plates, media are stirred and disk-holders are transferred to new wells after defined periods of time. After filtration, drug concentration in dissolution media is quantified by Ultra Performance Liquid Chromatography (UPLC) and solid state property of the disk is characterized by Raman spectroscopy. MINDISS was identified as an easy-to-use tool for rapid, parallel determination of DIDR of compounds that requires only small amounts of compound and of dissolution medium. Results obtained with marketed drugs in MINDISS correlate well with large scale DIDR methods and indicate that MINDISS can be used for (1) rank-ordering of compounds by intrinsic dissolution in late phase discovery and early development, (2) comparison of polymorphic forms and salts, (3) screening and selection of appropriate dissolution media, and (4) characterization of the intestinal release behavior of compounds along the gastro intestinal tract by changing biorelevant media during experiments. Copyright © 2015 Elsevier B.V. All rights reserved.

Real-time high-resolution PC-based system for measurement of errors on compact disks

NASA Astrophysics Data System (ADS)

Tehranchi, Babak; Howe, Dennis G.

1994-10-01

Hardware and software utilities are developed to directly monitor the Eight-to-Fourteen (EFM) demodulated data bytes at the input of a CD player's Cross-Interleaved Reed-Solomon Code (CIRC) block decoder. The hardware is capable of identifying erroneous data with single-byte resolution in the serial data stream read from a Compact Disc by a CDD 461 Philips CD-ROM drive. In addition, the system produces graphical maps that show the physical location of the measured errors on the entire disc, or via a zooming and planning feature, on user selectable local disc regions.

Compact forced simple-shear sample for studying shear localization in materials

DOE PAGES

Gray, George Thompson; Vecchio, K. S.; Livescu, Veronica

2015-11-06

In this paper, a new specimen geometry, the compact forced-simple-shear specimen (CFSS), has been developed as a means to achieve simple shear testing of materials over a range of temperatures and strain rates. The stress and strain state in the gage section is designed to produce essentially “pure” simple shear, mode II in-plane shear, in a compact-sample geometry. The 2-D plane of shear can be directly aligned along specified directional aspects of a material's microstructure of interest; i.e., systematic shear loading parallel, at 45°, and orthogonal to anisotropic microstructural features in a material such as the pancake-shaped grains typical inmore » many rolled structural metals, or to specified directions in fiber-reinforced composites. Finally, the shear-stress shear-strain response and the damage evolution parallel and orthogonal to the pancake grain morphology in 7039-Al are shown to vary significantly as a function of orientation to the microstructure.« less

N18, powder metallurgy superalloy for disks: Development and applications

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

Guedou, J.Y.; Lautridou, J.C.; Honnorat, Y.

1993-08-01

The preliminary industrial development of a powder metallurgy (PM) superalloy, designated N18, for disk applications has been completed. This alloy exhibits good overall mechanical properties after appropriate processing of the material. These properties have been measured on both isothermally forged and extruded billets, as well as on specimens cut from actual parts. The temperature capability of the alloy is about 700 C for long-term applications and approximately 750 C for short-term use because of microstructural instability. Further improvements in creep and crack propagation properties, without significant reduction in tensile strength, are possible through appropriate thermomechanical processing, which results in amore » large controlled grain size. Spin pit tests on subscale disks have confirmed that the N18 alloy has a higher resistance than PM Astrology and is therefore an excellent alloy for modern turbine disk applications.« less

Fracture of Composite Compact Tension Specimens

DTIC Science & Technology

1975-01-01

E: lb/in.; X 10* M.: Fiber Volume, % 1002 S- glass /epoxy Unidirectional Crossply 6.9 4.7 2.3 4.7 1.0 1.1 0.28 0.14 55 MOD 1-5208...configuration used in most of the fracture experiments is shown in Fig. 1. In unidirectional S- glass /epoxy specimens the fiber direction with respect to...conducted only with 0° or 90° fiber orientation. Cross-ply specimens of both S- glass and graphite were tested with the outer plies oriented at 0°, 45

Stress intensity factor in a tapered specimen

NASA Technical Reports Server (NTRS)

Xue-Hui, L.; Erdogan, F.

1985-01-01

The general problem of a tapered specimen containing an edge crack is formulated in terms of a system of singular integral equations. The equations are solved and the stress intensity factor is calculated for a compact and for a slender tapered specimen, the latter simulating the double cantilever beam. The results are obtained primarily for a pair of concentrated forces and for crack surface wedge forces. The stress intensity factors are also obtained for a long strip under uniform tension which contains inclined edge cracks.

Underwater explosive compaction-sintering of tungsten-copper coating on a copper surface

NASA Astrophysics Data System (ADS)

Chen, Xiang; Li, Xiaojie; Yan, Honghao; Wang, Xiaohong; Chen, Saiwei

2018-01-01

This study investigated underwater explosive compaction-sintering for coating a high-density tungsten-copper composite on a copper surface. First, 50% W-50% Cu tungsten-copper composite powder was prepared by mechanical alloying. The composite powder was pre-compacted and sintered by hydrogen. Underwater explosive compaction was carried out. Finally, a high-density tungsten-copper coating was obtained by diffusion sintering of the specimen after explosive compaction. A simulation of the underwater explosive compaction process showed that the peak value of the pressure in the coating was between 3.0 and 4.8 GPa. The hardness values of the tungsten-copper layer and the copper substrate were in the range of 87-133 and 49 HV, respectively. The bonding strength between the coating and the substrate was approximately 100-105 MPa.

Effect of thickness and surface modifications on flexural strength of monolithic zirconia.

PubMed

Ozer, Fusun; Naden, Andrew; Turp, Volkan; Mante, Francis; Sen, Deniz; Blatz, Markus B

2017-10-14

A recommended minimum thickness for monolithic zirconia restorations has not been reported. Assessing a proper thickness that has the necessary load-bearing capacity but also conserves dental hard tissues is essential. The purpose of this in vitro study was to evaluate the effect of thickness and surface modifications on monolithic zirconia after simulated masticatory stresses. Monolithic zirconia disks (10 mm in diameter) were fabricated with 1.3 mm and 0.8 mm thicknesses. For each thickness, 21 disks were fabricated. The specimens of each group were further divided into 3 subgroups (n=7) according to the surface treatments applied: untreated (control), airborne-particle abrasion with 50-μm Al 2 O 3 particles at a pressure of 400 kPa at 10 mm, and grinding with a diamond rotary instrument followed by polishing. The biaxial flexure strength was determined by using a piston-on-3-balls technique in a universal testing machine. Flexural loading was applied with a 1.4-mm diameter steel cylinder, centered on the disk, at a crosshead speed of 0.5 mm/min until fracture occurred. X-ray diffraction (XRD) and scanning electron microscopy (SEM) analyses were performed. The data were statistically analyzed with 2-way ANOVA, Tamhane T2, 1-way ANOVA, and Student t tests (α=.05). The 1.3-mm specimens had significantly higher flexural strength than the 0.8-mm specimens (P<.05). Airborne-particle abrasion significantly increased the flexural strength (P<.05). Grinding and polishing did not affect the flexural strength of the specimens (P>.05). The mean flexural strength of 0.8-mm and 1.3-mm thick monolithic zirconia was greater than reported masticatory forces. Airborne-particle abrasion increased the flexural strength of monolithic zirconia. Grinding did not affect flexural strength if subsequently polished. Copyright © 2017 Editorial Council for the Journal of Prosthetic Dentistry. Published by Elsevier Inc. All rights reserved.

Development of Mini-Compact Tension Test Method for Determining Fracture Toughness Master Curves for Reactor Pressure Vessel Steels

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

Sokolov, Mikhail A.

Small specimens are playing the key role in evaluating properties of irradiated materials. The use of small specimens provides several advantages. Typically, only a small volume of material can be irradiated in a reactor at desirable conditions in terms of temperature, neutron flux, and neutron dose. A small volume of irradiated material may also allow for easier handling of specimens. Smaller specimens reduce the amount of radioactive material, minimizing personnel exposures and waste disposal. However, use of small specimens imposes a variety of challenges as well. These challenges are associated with proper accounting for size effects and transferability of smallmore » specimen data to the real structures of interest. Any fracture toughness specimen that can be made out of the broken halves of standard Charpy specimens may have exceptional utility for evaluation of reactor pressure vessels (RPVs) since it would allow one to determine and monitor directly actual fracture toughness instead of requiring indirect predictions using correlations established with impact data. The Charpy V-notch specimen is the most commonly used specimen geometry in surveillance programs. Validation of the mini compact tension specimen (mini-CT) geometry has been performed on previously well characterized Midland beltline Linde 80 (WF-70) weld in the unirradiated condition. It was shown that the fracture toughness transition temperature, To, measured by these Mini-CT specimens is almost the same as To value that was derived from various larger fracture toughness specimens. Moreover, an International collaborative program has been established to extend the assessment and validation efforts to irradiated Linde 80 weld metal. The program is underway and involves the Oak Ridge National Laboratory (ORNL), Central Research Institute for Electrical Power Industry (CRIEPI), and Electric Power Research Institute (EPRI). The irradiated Mini-CT specimens from broken halves of previously tested Charpy specimens of Midland beltline weld have been machined and just arrived to ORNL as part of this international collaboration. The ORNL will initiate tests of the irradiated Linde 80 weld in FY2017 and results of this international program will be reported in FY2018.« less

Effectiveness of Shot Peening in Suppressing Fatigue Cracking at Non-Metallic Inclusions in Udimet(trademark) 720

NASA Technical Reports Server (NTRS)

Barrie, Robert L.; Gabb, Timothy P.; Telesman, Jack; Kantzos, Peter T.; Prescenzi, Anthony; Biles, Tiffany; Bonacuse, Peter J.

2005-01-01

The fatigue lives of modern powder metallurgy disk alloys can be reduced by over an order of magnitude by surface cracking at inherent non-metallic inclusions. The objective of this work was to study the effectiveness of shot peening in suppressing LCF crack initiation and growth at surface nonmetallic inclusions. Inclusions were carefully introduced at elevated levels during powder metallurgy processing of the nickel-base disk superalloy Udimet 720. Multiple strain-controlled fatigue tests were then performed on machined specimens at 427 and 650 C in peened and unpeened conditions. Analyses were performed to compare the low cycle fatigue lives and failure initiation sites as a function of inclusion content, shot peening, and fatigue conditions. A large majority of the failures in as-machined specimens with introduced inclusions occurred at cracks initiating from inclusions intersecting the specimen surface. The inclusions could reduce fatigue life by up to 100X. Large inclusions had the greatest effect on life in tests at low strain ranges and high strain ratios. Shot peening can be used to improve life in these conditions by reducing the most severe effects of inclusions.

New Optical Card for Sneaker’s Network in Place of Electronic Clinical Record

NASA Astrophysics Data System (ADS)

Goto, Kenya; Satsukawa, Takatoshi; Chiba, Seisho; Ohmori, Takaaki

2006-02-01

In order to solve problems in electronic medical records, a new optical card of the digital versatile disk (DVD) type with higher capacity and lower cost than conventional compact disc recording (CD-R)-type cards has been developed, which is thinner, stronger and wearable like a credit card.

The Versatility of Photo CD Technology in the Classroom.

ERIC Educational Resources Information Center

Mustoe, Myles

The Kodak Photo CD (compact disk) system provides a fun, new, very accessible way to integrate images into geography classroom presentations. Graphicacy deals with spatial information that can only be expressed by a graph, map, or photograph. The importance for geography students to develop visual observation and graphic interpretive skills is…

Kodak's Photo CD and Proposed Photo YCC Color Standard.

ERIC Educational Resources Information Center

Urrows, Henry; Urrows, Elizabeth

1991-01-01

Describes new technology being developed by Eastman Kodak for storing 35mm color photos on compact disk (CD) and discusses its applications for desktop publishing. Benefits of photo CD and costs are examined, a proposed universal color standard that is an improved way to represent color digitally is explained, and software is discussed. (LRW)

Big Hand Produces CD-I World Disc--First Title Authored Entirely with MediaMogul.

ERIC Educational Resources Information Center

Buckman, Brad; Grant, Valerie

1993-01-01

Discusses Big Hand Productions' development of CD-I-WORLD, an interactive multimedia magazine on compact disk, designed for mass appeal and complete with advertising. Features of MediaMogul, the prepackaged authoring software that made production of this innovation possible, are described. Sample screen displays are included. (EA)

NuSTAR constraints on coronal cutoffs in Swift-BAT selected Seyfert 1 AGN

NASA Astrophysics Data System (ADS)

Kamraj, Nikita; Harrison, Fiona; Balokovic, Mislav; Brightman, Murray; Stern, Daniel

2017-08-01

The continuum X-ray emission from Active Galactic Nuclei (AGN) is believed to originate in a hot, compact corona above the accretion disk. Compton upscattering of UV photons from the inner accretion disk by coronal electrons produces a power law X-ray continuum with a cutoff at energies determined by the electron temperature. The NuSTAR observatory, with its high sensitivity in hard X-rays, has enabled detailed broadband modeling of the X-ray spectra of AGN, thereby allowing tight constraints to be placed on the high-energy cutoff of the X-ray continuum. Recent detections of low cutoff energies in Seyfert 1 AGN in the NuSTAR band have motivated us to pursue a systematic search for low cutoff candidates in Swift-BAT detected Seyfert 1 AGN that have been observed with NuSTAR. We use our constraints on the cutoff energy to map out the location of these sources on the compactness - temperature diagram for AGN coronae, and discuss the implications of low cutoff energies for the cooling and thermalization mechanisms in the corona.

Euler force actuation mechanism for siphon valving in compact disk-like microfluidic chips.

PubMed

Deng, Yongbo; Fan, Jianhua; Zhou, Song; Zhou, Teng; Wu, Junfeng; Li, Yin; Liu, Zhenyu; Xuan, Ming; Wu, Yihui

2014-03-01

Based on the Euler force induced by the acceleration of compact disk (CD)-like microfluidic chip, this paper presents a novel actuation mechanism for siphon valving. At the preliminary stage of acceleration, the Euler force in the tangential direction of CD-like chip takes the primary place compared with the centrifugal force to function as the actuation of the flow, which fills the siphon and actuates the siphon valving. The Euler force actuation mechanism is demonstrated by the numerical solution of the phase-field based mathematical model for the flow in siphon valve. In addition, experimental validation is implemented in the polymethylmethacrylate-based CD-like microfluidic chip manufactured using CO2 laser engraving technique. To prove the application of the proposed Euler force actuation mechanism, whole blood separation and plasma extraction has been conducted using the Euler force actuated siphon valving. The newly introduced actuation mechanism overcomes the dependence on hydrophilic capillary filling of siphon by avoiding external manipulation or surface treatments of polymeric material. The sacrifice for highly integrated processing in pneumatic pumping technique is also prevented by excluding the volume-occupied compressed air chamber.

Development of radon sources with a high stability and a wide range

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

Fukutsu, K.; Yamada, Y.

A solid {sup 222}Rn (radon) source using a fibrous and porous SiC ceramic disk was developed. The emission rate of radon emanated from the disk depended on the content of {sup 226}Ra and the sintering temperature. A {sup 226}Ra sulfate ({sup 226}RaSO{sub 4}) solution was dropped on a fibrous SiC ceramic disk (33 mmφ) of 1 mm in thickness, and sintered at 400 °C. The radon concentration from a disk containing {sup 226}Ra of 1.85 MBq was measured to be 38 kBq m{sup −3} at a carrier airflow rate of 0.5 L min{sup −1}. By adjusting the {sup 226}Ra contentmore » or the sweep airflow rate, the radon concentrations were easily controlled over a wide range of over three orders of magnitude. The concentration was very stable for a long term. The compactness of the source disk made is easy for handling the source container and the shielding of gamma radiation from {sup 226}Ra and its decay products. Such advantages in a radon generation system are desirable for experiments of high-level, large-scale radon exposure.« less

Innovative opto-mechanical design of a laser head for compact thin-disk

NASA Astrophysics Data System (ADS)

Macúchová, Karolina; Smrž, Martin; Řeháková, Martina; Mocek, Tomáš

2016-11-01

We present recent progress in design of innovative versatile laser head for lasers based on thin-disk architecture which are being constructed at the HiLASE centre of the IOP in the Czech Republic. Concept of thin-disk laser technology allows construction of lasers providing excellent beam quality with high average output power and optical efficiency. Our newly designed thin-disk carrier and pump module comes from optical scheme consisting of a parabolic mirror and roof mirrors proposed in 90's. However, mechanical parts and a cooling system were in-house simplified and tailor-made to medium power lasers since no suitable setup was commercially available. Proposed opto-mechanical design is based on stable yet easily adjustable mechanics. The only water nozzle-cooled component is a room-temperature-operated thindisk mounted on a special cooling finger. Cooling of pump optics was replaced by heat conductive transfer from mirrors made of special Al alloy to a massive brass baseplate. Such mirrors are easy to manufacture and very cheap. Presented laser head was manufactured and tested in construction of Er and Yb doped disk lasers. Details of the latest design will be presented.

High resolution optical shaft encoder for motor speed control based on an optical disk pick-up

NASA Astrophysics Data System (ADS)

Yeh, Wei-Hung; Bletscher, Warren; Mansuripur, M.

1998-08-01

Using a three-beam optical pick-up from a compact disk player and a flexible, shaft-mounted diffraction grating, we obtain information about the rotation speed and angular position of the motor's spindle. This information may be used for feedback to the motor for smooth operation. Due to the small size of the focused spot and the built-in auto-focus mechanism of the optical head, the proposed encoder can achieve submicrometer resolution. With high resolution, reliable operation, and low-cost elements, the proposed method is suitable for rotary and linear motion control where accurate positioning of an object is required.

Array-on-a-disk? How Blu-ray technology can be applied to molecular diagnostics.

PubMed

Morais, Sergi; Tortajada-Genaro, Luis; Maquieira, Angel

2014-09-01

This editorial comments on the balance and perspectives of compact disk technology applied to molecular diagnostics. The development of sensitive, rapid and multiplex assays using Blu-ray technology for the determination of biomarkers, drug allergens, pathogens and detection of infections would have a direct impact on diagnostics. Effective tests for use in clinical, environmental and food applications require versatile and low-cost platforms as well as cost-effective detectors. Blu-ray technology accomplishes those requirements and advances on the concept of high density arrays for massive screening to achieve the demands of point of care or in situ analysis.

High signal intensity of intervertebral calcified disks on T1-weighted MR images resulting from fat content.

PubMed

Malghem, Jacques; Lecouvet, Frédéric E; François, Robert; Vande Berg, Bruno C; Duprez, Thierry; Cosnard, Guy; Maldague, Baudouin E

2005-02-01

To explain a cause of high signal intensity on T1-weighted MR images in calcified intervertebral disks associated with spinal fusion. Magnetic resonance and radiological examinations of 13 patients were reviewed, presenting one or several intervertebral disks showing a high signal intensity on T1-weighted MR images, associated both with the presence of calcifications in the disks and with peripheral fusion of the corresponding spinal segments. Fusion was due to ligament ossifications (n=8), ankylosing spondylitis (n=4), or posterior arthrodesis (n=1). Imaging files included X-rays and T1-weighted MR images in all cases, T2-weighted MR images in 12 cases, MR images with fat signal suppression in 7 cases, and a CT scan in 1 case. Histological study of a calcified disk from an anatomical specimen of an ankylosed lumbar spine resulting from ankylosing spondylitis was examined. The signal intensity of the disks was similar to that of the bone marrow or of perivertebral fat both on T1-weighted MR images and on all sequences, including those with fat signal suppression. In one of these disks, a strongly negative absorption coefficient was focally measured by CT scan, suggesting a fatty content. The histological examination of the ankylosed calcified disk revealed the presence of well-differentiated bone tissue and fatty marrow within the disk. The high signal intensity of some calcified intervertebral disks on T1-weighted MR images can result from the presence of fatty marrow, probably related to a disk ossification process in ankylosed spines.

Compact portable diffraction moire interferometer

DOEpatents

Deason, Vance A.; Ward, Michael B.

1989-01-01

A compact and portable moire interferometer used to determine surface deformations of an object. The improved interferometer is comprised of a laser beam, optical and fiber optics devices coupling the beam to one or more evanescent wave splitters, and collimating lenses directing the split beam at one or more specimen gratings. Observation means including film and video cameras may be used to view and record the resultant fringe patterns.

Hiding in Plain Sight: An Abundance of Compact Massive Spheroids in the Local Universe

NASA Astrophysics Data System (ADS)

Graham, Alister W.; Dullo, Bililign T.; Savorgnan, Giulia A. D.

2015-05-01

It has been widely remarked that compact, massive, elliptical-like galaxies are abundant at high redshifts but exceedingly rare in the universe today, implying significant evolution such that their sizes at z ˜ 2 ± 0.6 have increased by factors of 3 to 6 to become today’s massive elliptical galaxies. These claims have been based on studies that measured the half-light radii of galaxies as though they are all single-component systems. Here we identify 21 spheroidal stellar systems within 90 Mpc that have half-light, major-axis radii {{R}e}≲ 2 kpc, stellar masses 0.7× {{10}11}\\lt {{M}*}/ {{M}⊙ }\\lt 1.4× {{10}11}, and Sérsic indices typically around a value of n = 2-3. This abundance of compact, massive spheroids in our own backyard—with a number density of 6.9× {{10}-6} Mpc-3 (or 3.5 × 10-5 Mpc-3 per unit dex-1 in stellar mass)—and with the same physical properties as the high-redshift galaxies, had been overlooked because they are encased in stellar disks that usually result in galaxy sizes notably larger than 2 kpc. Moreover, this number density is a lower limit because it has not come from a volume-limited sample. The actual density may be closer to 10-4, although further work is required to confirm this. We therefore conclude that not all massive “spheroids” have undergone dramatic structural and size evolution since z ˜ 2 ± 0.6. Given that the bulges of local early-type disk galaxies are known to consist of predominantly old stars that existed at z ˜ 2, it seems likely that some of the observed high-redshift spheroids did not increase in size by building (three-dimensional) triaxial envelopes as commonly advocated, and that the growth of (two-dimensional) disks has also been important over the past 9-11 billion years.

Ultrasonic scanning system for imaging flaw growth in composites

NASA Technical Reports Server (NTRS)

Kiraly, L. J.; Meyn, E. H.

1982-01-01

A system for measuring and visually representing damage in composite specimens while they are being loaded was demonstrated. It uses a hobbiest grade microcomputer system to control data taking and image processing. The system scans operator selected regions of the specimen while it is under load in a tensile test machine and measures internal damage by the attenuation of a 2.5 MHz ultrasonic beam passed through the specimen. The microcomputer dynamically controls the position of ultrasonic transducers mounted on a two axis motor driven carriage. As many as 65,536 samples can be taken and filed on a floppy disk system in less than four minutes.

Prediction and Verification of Ductile Crack Growth from Simulated Defects in Strength Overmatched Butt Welds

NASA Technical Reports Server (NTRS)

Nishioka, Owen S.

1997-01-01

Defects that develop in welds during the fabrication process are frequently manifested as embedded flaws from lack of fusion or lack of penetration. Fracture analyses of welded structures must be able to assess the effect of such defects on the structural integrity of weldments; however, the transferability of R-curves measured in laboratory specimens to defective structural welds has not been fully examined. In the current study, the fracture behavior of an overmatched butt weld containing a simulated buried, lack-of-penetration defect is studied. A specimen designed to simulate pressure vessel butt welds is considered; namely, a center crack panel specimen, of 1.25 inch by 1.25 inch cross section, loaded in tension. The stress-relieved double-V weld has a yield strength 50% higher than that of the plate material, and displays upper shelf fracture behavior at room temperature. Specimens are precracked, loaded monotonically while load-CMOD measurements are made, then stopped and heat tinted to mark the extent of ductile crack growth. These measurements are compared to predictions made using finite element analysis of the specimens using the fracture mechanics code Warp3D, which models void growth using the Gurson-Tvergaard dilitant plasticity formulation within fixed sized computational cells ahead of the crack front. Calibrating data for the finite element analyses, namely cell size and initial material porosities are obtained by matching computational predictions to experimental results from tests of welded compact tension specimens. The R-curves measured in compact tension specimens are compared to those obtained from multi-specimen weld tests, and conclusions as to the transferability of R-curves is discussed.

Understanding and optimizing the dual excipient functionality of sodium lauryl sulfate in tablet formulation of poorly water soluble drug: wetting and lubrication.

PubMed

Aljaberi, Ahmad; Chatterji, Ashish; Dong, Zedong; Shah, Navnit H; Malick, Waseem; Singhal, Dharmendra; Sandhu, Harpreet K

2013-01-01

To evaluate and optimize sodium lauryl sulfate (SLS) and magnesium stearate (Mg.St) levels, with respect to dissolution and compaction, in a high dose, poorly soluble drug tablet formulation. A model poorly soluble drug was formulated using high shear aqueous granulation. A D-optimal design was used to evaluate and model the effect of granulation conditions, size of milling screen, SLS and Mg.St levels on tablet compaction and ejection. The compaction profiles were generated using a Presster(©) compaction simulator. Dissolution of the kernels was performed using a USP dissolution apparatus II and intrinsic dissolution was determined using a stationary disk system. Unlike kernels dissolution which failed to discriminate between tablets prepared with various SLS contents, the intrinsic dissolution rate showed that a SLS level of 0.57% was sufficient to achieve the required release profile while having minimal effect on compaction. The formulation factors that affect tablet compaction and ejection were identified and satisfactorily modeled. The design space of best factor setting to achieve optimal compaction and ejection properties was successfully constructed by RSM analysis. A systematic study design helped identify the critical factors and provided means to optimize the functionality of key excipient to design robust drug product.

Lamb Wave Propagation in a Restricted Geometry Composite PI-Joint Specimen (Preprint)

DTIC Science & Technology

2011-11-01

adhesive, and were located along the length and height of the specimen as depicted in Figure 3. The sensors were 6.35 mm round disks of PZT , with a...in both cases for R1, R2, and R3. 3D Finite Element Model Geometry 200mm length 50mm width 140mm height x z y PZT Actuation Sensor...health monitoring using scanning laser vibrometry: III. Lamb waves for fatigue crack detection”, Smart Mater. Struct., Vol. 14, No. 6, 2005. 16

Toward an Astrophysical Theory of Chondrites

NASA Technical Reports Server (NTRS)

Shang, Hsien; Shu, Frank H.; Lee, Typhoon

1996-01-01

Sunlike stars are born with disks. Based on our recently developed model to understand how a magnetized new star interacts with its surrounding accretion disk, we advanced an astrophysical theory for the early solar system. The aerodynamic drag of a magnetocentrifugally driven wind out of the inner edge of a shaded disk could expose solid bodies lifted into the heat of direct sunlight, when material is still accreting onto the protosun. Chondrules, calcium-aluminum-rich inclusions (CAI's), and rims could form along the flight for typical self-consistent parameters of the outflow in different stages of star formation. The process gives a natural sorting mechanism that explains the size distribution of CAI's and chondrules, as well as their associated rims. Chondritic bodies then subsequently form by compaction of the processed solids with the ambient nebular dust comprising the matrices after their reentry at great distances from the original launch radius.

Exploring Stability of General Relativistic Accretion Disks

NASA Astrophysics Data System (ADS)

Korobkin, Oleg; Abdikamalov, Ernazar; Schnetter, Erik; Stergioulas, Nikolaos; Zink, Burkhard

2011-04-01

Self-gravitating relativistic disks around black holes can form as transient structures in a number of astrophysical scenarios, involving core collapse of massive stars and mergers of compact ob jects. I will present results on our recent study of the stability of such disks against runaway and non-axisymmetric instabilities, which we explore using three-dimensional hydrodynamics simulations in full general relativity. All of our models develop unstable non-axisymmetric modes on a dynamical timescale. We observe two distinct types of instabilities: the Papaloizou-Pringle and the so-called intermediate type instabilities. The development of the non-axisymmetric mode with azimuthal number m=1 is accompanied by an outspiraling motion of the black hole, which significantly amplifies the growth rate of the m=1 mode in some cases. We will discuss the types, growth rates and pattern speeds of the unstable modes, as well as the detectability of the gravitational waves from such objects.

Nonlinear terahertz devices utilizing semiconducting plasmonic metamaterials

DOE PAGES

Seren, Huseyin R.; Zhang, Jingdi; Keiser, George R.; ...

2016-01-26

The development of responsive metamaterials has enabled the realization of compact tunable photonic devices capable of manipulating the amplitude, polarization, wave vector and frequency of light. Integration of semiconductors into the active regions of metallic resonators is a proven approach for creating nonlinear metamaterials through optoelectronic control of the semiconductor carrier density. Metal-free subwavelength resonant semiconductor structures offer an alternative approach to create dynamic metamaterials. We present InAs plasmonic disk arrays as a viable resonant metamaterial at terahertz frequencies. Importantly, InAs plasmonic disks exhibit a strong nonlinear response arising from electric field-induced intervalley scattering, resulting in a reduced carrier mobilitymore » thereby damping the plasmonic response. here, we demonstrate nonlinear perfect absorbers configured as either optical limiters or saturable absorbers, including flexible nonlinear absorbers achieved by transferring the disks to polyimide films. Nonlinear plasmonic metamaterials show potential for use in ultrafast terahertz (THz) optics and for passive protection of sensitive electromagnetic devices.« less

Nonlinear terahertz devices utilizing semiconducting plasmonic metamaterials

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

Seren, Huseyin R.; Zhang, Jingdi; Keiser, George R.

The development of responsive metamaterials has enabled the realization of compact tunable photonic devices capable of manipulating the amplitude, polarization, wave vector and frequency of light. Integration of semiconductors into the active regions of metallic resonators is a proven approach for creating nonlinear metamaterials through optoelectronic control of the semiconductor carrier density. Metal-free subwavelength resonant semiconductor structures offer an alternative approach to create dynamic metamaterials. We present InAs plasmonic disk arrays as a viable resonant metamaterial at terahertz frequencies. Importantly, InAs plasmonic disks exhibit a strong nonlinear response arising from electric field-induced intervalley scattering, resulting in a reduced carrier mobilitymore » thereby damping the plasmonic response. here, we demonstrate nonlinear perfect absorbers configured as either optical limiters or saturable absorbers, including flexible nonlinear absorbers achieved by transferring the disks to polyimide films. Nonlinear plasmonic metamaterials show potential for use in ultrafast terahertz (THz) optics and for passive protection of sensitive electromagnetic devices.« less

Foreign Object Damage of Two Gas-Turbine Grade Silicon Nitrides in a Thin Disk Configuration

NASA Technical Reports Server (NTRS)

Choi, Sung R.; Pereira, J. Michael; Janosik, Lesley A.; Bhatt, Ramakrishna T.

2003-01-01

Foreign object damage (FOD) behavior of two commercial gas-turbine grade silicon nitrides, AS800 and SN282, was determined at ambient temperature through post-impact strength testing for thin disks impacted by steel-ball projectiles with a diameter of 1.59 mm in a velocity range from 115 to 440 m/s. AS800 silicon nitride exhibited a greater FOD resistance than SN282, primarily due to its greater value of fracture toughness (K(sub IC)). The critical impact velocity in which the corresponding post-impact strength yielded the lowest value was V(sub c) approx. 440 and 300 m/s for AS800 and SN282, respectively. A unique lower-strength regime was typified for both silicon nitrides depending on impact velocity, attributed to significant radial cracking. The damages generated by projectile impact were typically in the forms of ring, radial, and cone cracks with their severity and combination being dependent on impact velocity. Unlike thick (3 mm) flexure bar specimens used in the previous studies, thin (2 mm) disk target specimens exhibited a unique backside radial cracking occurring on the reverse side just beneath the impact sites at and above impact velocity of 160 and 220 m/s for SN282 and AS800, respectively.

Improving spinning disk confocal microscopy by preventing pinhole cross-talk for intravital imaging

PubMed Central

Shimozawa, Togo; Yamagata, Kazuo; Kondo, Takefumi; Hayashi, Shigeo; Shitamukai, Atsunori; Konno, Daijiro; Matsuzaki, Fumio; Takayama, Jun; Onami, Shuichi; Nakayama, Hiroshi; Kosugi, Yasuhito; Watanabe, Tomonobu M.; Fujita, Katsumasa; Mimori-Kiyosue, Yuko

2013-01-01

A recent key requirement in life sciences is the observation of biological processes in their natural in vivo context. However, imaging techniques that allow fast imaging with higher resolution in 3D thick specimens are still limited. Spinning disk confocal microscopy using a Yokogawa Confocal Scanner Unit, which offers high-speed multipoint confocal live imaging, has been found to have wide utility among cell biologists. A conventional Confocal Scanner Unit configuration, however, is not optimized for thick specimens, for which the background noise attributed to “pinhole cross-talk,” which is unintended pinhole transmission of out-of-focus light, limits overall performance in focal discrimination and reduces confocal capability. Here, we improve spinning disk confocal microscopy by eliminating pinhole cross-talk. First, the amount of pinhole cross-talk is reduced by increasing the interpinhole distance. Second, the generation of out-of-focus light is prevented by two-photon excitation that achieves selective-plane illumination. We evaluate the effect of these modifications and test the applicability to the live imaging of green fluorescent protein-expressing model animals. As demonstrated by visualizing the fine details of the 3D cell shape and submicron-size cytoskeletal structures inside animals, these strategies dramatically improve higher-resolution intravital imaging. PMID:23401517

Improving spinning disk confocal microscopy by preventing pinhole cross-talk for intravital imaging.

PubMed

Shimozawa, Togo; Yamagata, Kazuo; Kondo, Takefumi; Hayashi, Shigeo; Shitamukai, Atsunori; Konno, Daijiro; Matsuzaki, Fumio; Takayama, Jun; Onami, Shuichi; Nakayama, Hiroshi; Kosugi, Yasuhito; Watanabe, Tomonobu M; Fujita, Katsumasa; Mimori-Kiyosue, Yuko

2013-02-26

A recent key requirement in life sciences is the observation of biological processes in their natural in vivo context. However, imaging techniques that allow fast imaging with higher resolution in 3D thick specimens are still limited. Spinning disk confocal microscopy using a Yokogawa Confocal Scanner Unit, which offers high-speed multipoint confocal live imaging, has been found to have wide utility among cell biologists. A conventional Confocal Scanner Unit configuration, however, is not optimized for thick specimens, for which the background noise attributed to "pinhole cross-talk," which is unintended pinhole transmission of out-of-focus light, limits overall performance in focal discrimination and reduces confocal capability. Here, we improve spinning disk confocal microscopy by eliminating pinhole cross-talk. First, the amount of pinhole cross-talk is reduced by increasing the interpinhole distance. Second, the generation of out-of-focus light is prevented by two-photon excitation that achieves selective-plane illumination. We evaluate the effect of these modifications and test the applicability to the live imaging of green fluorescent protein-expressing model animals. As demonstrated by visualizing the fine details of the 3D cell shape and submicron-size cytoskeletal structures inside animals, these strategies dramatically improve higher-resolution intravital imaging.

Spectroscopic Observations of the Mass Donor Star in SS 433

NASA Astrophysics Data System (ADS)

Hillwig, T. C.; Gies, D. R.

2008-03-01

The microquasar SS 433 is an interacting massive binary consisting of an evolved mass donor and a compact companion that ejects relativistic jets. The mass donor was previously identified through spectroscopic observations of absorption lines in the blue part of the spectrum that showed Doppler shifts associated with orbital motion and strength variations related to the orbital modulation of the star-to-disk flux ratio and to disk obscuration. However, subsequent observations revealed other absorption features that lacked these properties and that were probably formed in the disk gas outflow. We present follow-up observations of SS 433 at orbital and precession phases identical to those from several previous studies, with the goals of confirming the detection of the mass donor spectrum and providing more reliable masses for the two system components. We show that the absorption features present as well as those previously observed almost certainly belong to the mass donor star, and find revised masses of 12.3 ± 3.3 and 4.3 ± 0.8 M⊙ for the mass donor and compact object, respectively. Based on observations obtained at the Gemini Observatory, which is operated by the Association of Universities for Research in Astronomy, Inc., under a cooperative agreement with the NSF on behalf of the Gemini partnership: the National Science Foundation (US), the Science and Technology Facilities Council (UK), the National Research Council (Canada), CONICYT (Chile), the Australian Research Council (Australia), CNPq (Brazil), and SECYT (Argentina).

ALMA Measurements of Circumstellar Material in the GQ Lup System

NASA Astrophysics Data System (ADS)

MacGregor, Meredith A.; Wilner, David J.; Czekala, Ian; Andrews, Sean M.; Dai, Y. Sophia; Herczeg, Gregory J.; Kratter, Kaitlin M.; Kraus, Adam L.; Ricci, Luca; Testi, Leonardo

2017-01-01

We present Atacama Large Millimeter/submillimeter Array observations of the GQ Lup system, a young Sun-like star with a substellar-mass companion in a wide-separation orbit. These observations of 870 μm continuum and CO J = 3-2 line emission with beam size ˜0.″3 (˜45 au) resolve the disk of dust and gas surrounding the primary star, GQ Lup A, and provide deep limits on any circumplanetary disk surrounding the companion, GQ Lup b. The circumprimary dust disk is compact with an FWHM of 59 ± 12 au, while the gas has a larger extent with a characteristic radius of 46.5 ± 1.8 au. By forward-modeling the velocity field of the circumprimary disk based on the CO emission, we constrain the mass of GQ Lup A to be M* = (1.03 ± 0.05) ∗ (d/156 pc) M⊙, where d is a known distance, and determine that we view the disk at an inclination angle of 60.°5 ± 0.°5 and a position angle of 346° ± 1°. The 3σ upper limit on the 870 μm flux density of any circumplanetary disk associated with GQ Lup b of <0.15 mJy implies an upper limit on the dust disk mass of <0.04 M⊕ for standard assumptions about optically thin emission. We discuss proposed mechanisms for the formation of wide-separation substellar companions given the non-detection of circumplanetary disks around GQ Lup b and other similar systems.

Mapping out the origins of compact stellar systems

NASA Astrophysics Data System (ADS)

Romanowsky, Aaron J.; Brodie, Jean P.; SAGES Collaboration

2017-03-01

We present a suite of extragalactic explorations of the origins and nature of globular clusters (GCs) and ultra-compact dwarfs (UCDs), and the connections between them. An example of GC metallicity bimodality is shown to reflect underlying, distinct metal-poor and metal-rich stellar halo populations. Metallicity-matching methods are used to trace the birth sites and epochs of GCs in giant E/S0s, pointing to clumpy disk galaxies at z ~ 3 for the metal-rich GCs, and to a combination of accreted and in-situ formation modes at z ~ 5-6 for the metal-poor GCs. An increasingly diverse zoo of compact stellar systems is being discovered, including objects that bridge the gaps between UCDs and faint fuzzies, and between UCDs and compact ellipticals. Many of these have properties pointing to origins as the stripped nuclei of larger galaxies, and a smoking-gun example is presented of an ω Cen-like star cluster embedded in a tidal stream.

Revealing the sub-AU asymmetries of the inner dust rim in the disk around the Herbig Ae star R Coronae Austrinae

NASA Astrophysics Data System (ADS)

Kraus, S.; Hofmann, K.-H.; Malbet, F.; Meilland, A.; Natta, A.; Schertl, D.; Stee, P.; Weigelt, G.

2009-12-01

Context: Unveiling the structure of the disks around intermediate-mass pre-main-sequence stars (Herbig Ae/Be stars) is essential for our understanding of the star and planet formation process. In particular, models predict that in the innermost AU around the star, the dust disk forms a “puffed-up” inner rim, which should result in a strongly asymmetric brightness distribution for disks seen under intermediate inclination. Aims: Our aim is to constrain the sub-AU geometry of the inner disk around the Herbig Ae star R CrA and search for the predicted asymmetries. Methods: Using the VLTI/AMBER long-baseline interferometer, we obtained 24 near-infrared (H- and K-band) spectro-interferometric observations on R CrA. Observing with three telescopes in a linear array configuration, each data set samples three equally spaced points in the visibility function, providing direct information about the radial intensity profile. In addition, the observations cover a wide position angle range (~97°), also probing the position angle dependence of the source brightness distribution. Results: In the derived visibility function, we detect the signatures of an extended (Gaussian FWHM ~ 25 mas) and a compact component (Gaussian FWHM ~ 5.8 mas), with the compact component contributing about two-thirds of the total flux (both in H- and K-band). The brightness distribution is highly asymmetric, as indicated by the strong closure phases (up to ~40°) and the detected position angle dependence of the visibilities and closure phases. To interpret these asymmetries, we employ various geometric as well as physical models, including a binary model, a skewed ring model, and a puffed-up inner rim model with a vertical or curved rim shape. For the binary and vertical rim model, no acceptable fits could be obtained. On the other hand, the skewed ring model and the curved puffed-up inner rim model allow us to simultaneously reproduce the measured visibilities and closure phases. From these models we derive the location of the dust sublimation radius (~0.4 AU), the disk inclination angle (~35°), and a north-south disk orientation (PA ~ 180-190°). Our curved puffed-up rim model can reproduce reasonably well the interferometric observables and the SED and suggests a luminosity of ~29 L⊙ and the presence of relatively large (⪆1.2 μm) Silicate dust grains. Our study also reveals discrepancies between the measured interferometric observables and the puffed-up inner rim models, providing important constraints for future refinements of these theoretical models. Perpendicular to the disk, two bow shock-like structures appear in the associated reflection nebula NGC 6729, suggesting that the detected sub-AU size disk is the driving engine of a large-scale outflow. Conclusions: Detecting, for the first time, strong non-localized asymmetries in the inner regions of a Herbig Ae disk, our study supports the existence of a puffed-up inner rim in YSO disks. Based on observations made with ESO telescopes at the La Silla Paranal Observatory under programme IDs 079.D-0370(A), 081.C-0272(A,B,C), and 081.C-0321(A).

Low temperature sintering of fluorapatite glass-ceramics.

PubMed

Denry, Isabelle; Holloway, Julie A

2014-02-01

Fluorapatite glass-ceramics have been shown to be excellent candidates as scaffold materials for bone grafts, however, scaffold production by sintering is hindered by concurrent crystallization of the glass. Objective, our goal was to investigate the effect of Ca/Al ratio on the sintering behavior of Nb-doped fluorapatite-based glasses in the SiO2-Al2O3-P2O5-MgO-Na2O-K2O-CaO-CaF2 system. Methods, glass compositions with Ca/Al ratio of 1 (A), 2 (B), 4 (C) and 19 (D) were prepared by twice melting at 1525°C for 3h. Glasses were either cast as cylindrical ingots or ground into powders. Disk-shaped specimens were prepared by either sectioning from the ingots or powder-compacting in a mold, followed by heat treatment at temperatures ranging between 700 and 1050°C for 1h. The density was measured on both sintered specimens and heat treated discs as controls. The degree of sintering was determined from these measurements. Results and Significance XRD showed that fluorapatite crystallized in all glass-ceramics. A high degree of sintering was achieved at 775°C for glass-ceramic D (98.99±0.04%), and 900°C for glass-ceramic C (91.31±0.10). Glass-ceramics A or B were only partially sintered at 1000°C (63.6±0.8% and 74.1±1.5%, respectively). SEM revealed a unique microstructure of micron-sized spherulitic fluorapatite crystals in glass-ceramics C and D. Increasing the Ca/Al ratio promoted low temperature sintering of fluorapatite glass-ceramics, which are traditionally difficult to sinter. Copyright © 2013 Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved.

The Electronic Library: The Student/Scholar Workstation, CD-ROM and Hypertext.

ERIC Educational Resources Information Center

Triebwasser, Marc A.

Predicting that a large component of the library of the not so distant future will be an electronic network of file servers where information is stored for access by personal computer workstations in remote locations as well as the library, this paper discusses innovative computer technologies--particularly CD-ROM (Compact Disk-Read Only Memory)…

How To Use the SilverPlatter Software To Search the ERIC CD ROM.

ERIC Educational Resources Information Center

Merrill, Paul F.

This manual provides detailed instructions for using SilverPlatter software to search the ERIC CD ROM (Compact Disk Read Only Memory), a large bibliographic database relating to education which contains reference information on numerous journal articles from over 750 journals cited in the "Current Index to Journals in Education" (CIJE),…

Large-scale vortices in compressible turbulent medium with the magnetic field

NASA Astrophysics Data System (ADS)

Gvaramadze, V. V.; Dimitrov, B. G.

1990-08-01

An averaged equation which describes the large scale vortices and Alfven waves generation in a compressible helical turbulent medium with a constant magnetic field is presented. The presence of the magnetic field leads to anisotropization of the vortex generation. Possible applications of the anisotropic vortex dynamo effect are accretion disks of compact objects.

A Class at Mount Holyoke College Uses "Frankenstein" as a Tool for Teaching Student Multimedia Techniques.

ERIC Educational Resources Information Center

Gose, Ben

1997-01-01

A Mount Holyoke College (Massachusetts) class on computer applications in history and the humanities, entitled "Frankenstein Meets Multimedia," uses topics from the 1818 novel as the basis for students to develop multimedia compact disks about it. The novel is used because its author was heavily influenced by the philosophy of the…

Relative astrometry of compact flaring structures in Sgr A* with polarimetric very long baseline interferometry

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

Johnson, Michael D.; Doeleman, Sheperd S.; Fish, Vincent L.

2014-10-20

We demonstrate that polarimetric interferometry can be used to extract precise spatial information about compact polarized flares of Sgr A*. We show that, for a faint dynamical component, a single interferometric baseline suffices to determine both its polarization and projected displacement from the quiescent intensity centroid. A second baseline enables two-dimensional reconstruction of the displacement, and additional baselines can self-calibrate using the flare, enhancing synthesis imaging of the quiescent emission. We apply this technique to simulated 1.3 mm wavelength observations of a 'hot spot' embedded in a radiatively inefficient accretion disk around Sgr A*. Our results indicate that, even withmore » current sensitivities, polarimetric interferometry with the Event Horizon Telescope can achieve ∼5 μas relative astrometry of compact flaring structures near Sgr A* on timescales of minutes.« less

Development and initial validation of a novel smoothed-particle hydrodynamics-based simulation model of trabecular bone penetration by metallic implants.

PubMed

Kulper, Sloan A; Fang, Christian X; Ren, Xiaodan; Guo, Margaret; Sze, Kam Y; Leung, Frankie K L; Lu, William W

2018-04-01

A novel computational model of implant migration in trabecular bone was developed using smoothed-particle hydrodynamics (SPH), and an initial validation was performed via correlation with experimental data. Six fresh-frozen human cadaveric specimens measuring 10 × 10 × 20 mm were extracted from the proximal femurs of female donors (mean age of 82 years, range 75-90, BV/TV ratios between 17.88% and 30.49%). These specimens were then penetrated under axial loading to a depth of 10 mm with 5 mm diameter cylindrical indenters bearing either flat or sharp/conical tip designs similar to blunt and self-tapping cancellous screws, assigned in a random manner. SPH models were constructed based on microCT scans (17.33 µm) of the cadaveric specimens. Two initial specimens were used for calibration of material model parameters. The remaining four specimens were then simulated in silico using identical material model parameters. Peak forces varied between 92.0 and 365.0 N in the experiments, and 115.5-352.2 N in the SPH simulations. The concordance correlation coefficient between experimental and simulated pairs was 0.888, with a 95%CI of 0.8832-0.8926, a Pearson ρ (precision) value of 0.9396, and a bias correction factor Cb (accuracy) value of 0.945. Patterns of bone compaction were qualitatively similar; both experimental and simulated flat-tipped indenters produced dense regions of compacted material adjacent to the advancing face of the indenter, while sharp-tipped indenters deposited compacted material along their peripheries. Simulations based on SPH can produce accurate predictions of trabecular bone penetration that are useful for characterizing implant performance under high-strain loading conditions. © 2017 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 36:1114-1123, 2018. © 2017 Orthopaedic Research Society. Published by Wiley Periodicals, Inc.

Effect of processing induced particle alignment on the fracture toughness and fracture behavior of multiphase dental ceramics.

PubMed

Gonzaga, Carla C; Okada, Cristina Yuri; Cesar, Paulo F; Miranda, Walter G; Yoshimura, Humberto N

2009-11-01

To investigate the processing induced particle alignment on fracture behavior of four multiphase dental ceramics (one porcelain, two glass-ceramics and a glass-infiltrated-alumina composite). Disks (Ø12 mm x 1.1mm-thick) and bars (3 mm x 4 mm x 20 mm) of each material were processed according to manufacturer instructions, machined and polished. Fracture toughness (K(Ic)) was determined by the indentation strength method using 3-point bending and biaxial flexure fixtures for the fracture of bars and disks, respectively. Microstructural and fractographic analyses were performed with scanning electron microscopy, energy dispersive spectroscopy and X-ray diffraction. The isotropic microstructure of the porcelain and the leucite-based glass-ceramic resulted in similar fracture toughness values regardless of the specimen geometry. On the other hand, materials containing second-phase particles with high aspect ratio (lithium disilicate glass-ceramic and glass-infiltrated-alumina composite) showed lower fracture toughness for disk specimens compared to bars. For the lithium disilicate glass-ceramic disks, it was demonstrated that the occurrence of particle alignment during the heat-pressing procedure resulted in an unfavorable pattern that created weak microstructural paths during the biaxial test. For the glass-infiltrated-alumina composite, the microstructural analysis showed that the large alumina platelets tended to align their large surfaces perpendicularly to the direction of particle deposition during slip casting of green preforms. The fracture toughness of dental ceramics with anisotropic microstructure should be determined by means of biaxial testing, since it results in lower values.

Protocol for Cohesionless Sample Preparation for Physical Experimentation

DTIC Science & Technology

2016-05-01

protocol for specimen preparation that will enable the use of soil strength curves based on expedient field classification testing (e.g., grain-size...void ratio and relative compaction, which compares field compaction to a laboratory maximum density. Gradation charts for the two materials used in...the failure stress. Ring shear testing was performed using the GCTS Residual-Ring Shear System SRS-150 in order to measure the peak torsional

Compact portable diffraction moire interferometer

DOEpatents

Deason, V.A.; Ward, M.B.

1988-05-23

A compact and portable moire interferometer used to determine surface deformations of an object. The improved interferometer is comprised of a laser beam, optical and fiber optics devices coupling the beam to one or more evanescent wave splitters, and collimating lenses directing the split beam at one or more specimen gratings. Observations means including film and video cameras may be used to view and record the resultant fringe patterns. 7 figs.

Dentin-Composite Bond Strength Measurement Using the Brazilian Disk Test

PubMed Central

Carrera, Carola A.; Chen, Yung-Chung; Li, Yuping; Rudney, Joel; Aparicio, Conrado; Fok, Alex

2016-01-01

Objectives This study presents a variant of the Brazilian disk test (BDT) for assessing the bond strength between composite resins and dentin. Methods Dentin-composite disks (φ 5 mm × 2 mm) were prepared using either Z100 or Z250 (3M ESPE) in combination with one of three adhesives, Adper Easy Bond (EB), Adper Scotchbond Multi-Purpose (MP) and Adper Single Bond (SB), and tested under diametral compression. Acoustic emission (AE) and digital image correlation (DIC) were used to monitor debonding of the composite from the dentin ring. A finite element (FE) model was created to calculate the bond strengths using the failure loads. Fracture modes were examined by scanning electron microscopy (SEM). Results Most specimens fractured along the dentin-resin composite interface. DIC and AE confirmed interfacial debonding immediately before fracture of the dentin ring. Results showed that the mean bond strength with EB (14.9±1.9 MPa) was significantly higher than with MP (13.2±2.4 MPa) or SB (12.9±3.0 MPa) (p<0.05); no significant difference was found between MP and SB (p>0.05). Z100 (14.5±2.3 MPa) showed higher bond strength than Z250 (12.7±2.5 MPa) (p<0.05). Majority of specimens (91.3%) showed an adhesive failure mode. EB failed mostly at the dentin-adhesive interface, whereas MP at the composite-adhesive interface; specimens with SB failed at the composite-adhesive interface and cohesively in the adhesive. Conclusions The BDT variant showed to be a suitable alternative for measuring the bond strength between dentin and composite, with zero premature failure, reduced variability in the measurements, and consistent failure at the dentin-composite interface. PMID:27395367

Reaction bonded silicon nitride prepared from wet attrition-milled silicon. [fractography

NASA Technical Reports Server (NTRS)

Herball, T. P.; Glasgow, T. K.; Shaw, N. J.

1980-01-01

Silicon powder wet milled in heptane was dried, compacted into test bar shape, helium-sintered, and then reaction bonded in nitrogen-4 volume percent hydrogen. As-nitrided bend strengths averaged approximately 290 MPa at both room temperature and 1400 C. Fracture initiation appeared to be associated with subsurface flaws in high strength specimens and both subsurface and surface flaws in low strength specimens.

Reaction bonded silicon nitride prepared from wet attrition-milled silicon

NASA Technical Reports Server (NTRS)

Herbell, T. P.; Glasgow, T. K.; Shaw, N. J.

1980-01-01

Silicon powder wet milled in heptane was dried, compacted into test bar shape, helium-sintered, and then reaction bonded in nitrogen-4 vol% hydrogen. As-nitrided bend strengths averaged approximately 290 MPa at both room temperature and 1400 C. Fracture initiation appeared to be associated with subsurface flaws in high-strength specimens and both subsurface and surface flaws in low-strength specimens.

A Study of Production of Miscibility Gap Alloys with Controlled Structures

NASA Technical Reports Server (NTRS)

Parr, R. A.; Johnston, M. H.; Burka, J. A.; Davis, J. H.; Lee, J. A.

1983-01-01

Composite materials were directionally solidified using a new technique to align the constituents longitudinally along the length of the specimen. In some instances a tin coating was applied and diffused into the sample to form a high transition temperature superconducting phase. The superconducting properties were measured and compared with the properties obtained for powder composites and re-directionally solidified powder compacts. The samples which were compacted and redirectionally solidified showed the highest transition temperature and wildest transition range. This indicates that both steps, powder compaction and resolidification, determine the final superconducting properties of the material.

Microbial Characterization Space Solid Wastes Treated with a Heat Melt Compactor

NASA Technical Reports Server (NTRS)

Strayer, Richard F.; Hummerick, Mary E.; Richards, Jeffrey T.; McCoy LaShelle E.; Roberts, Michael S.; Wheeler, Raymond M.

2012-01-01

The on going purpose of the project efforts was to characterize and determine the fate of microorganisms in space-generated solid wastes before and after processing by candidate solid waste processing. For FY 11, the candidate technology that was assessed was the Heat Melt Compactor (HMC). The scope included five HMC. product disks produced at ARC from either simulated space-generated trash or from actual space trash, Volume F compartment wet waste, returned on STS 130. This project used conventional microbiological methods to detect and enumerate microorganisms in heat melt compaction (HMC) product disks as well as surface swab samples of the HMC hardware before and after operation. In addition, biological indicators were added to the STS trash prior to compaction in order to determine if these spore-forming bacteria could survive the HMC processing conditions, i.e., high temperature (160 C) over a long duration (3 hrs). To ensure that surface dwelling microbes did not contaminate HMC product disk interiors, the disk surfaces were sanitized with 70% alcohol. Microbiological assays were run before and after sanitization and found that sanitization greatly reduced the number of identified isolates but did not totally eliminate them. To characterize the interior of the disks, ten 1.25 cm diameter core samples were aseptically obtained for each disk. These were run through the microbial characterization analyses. Low counts of bacteria, on the order of 5 to 50 per core, were found, indicating that the HMC operating conditions might not be sufficient for waste sterilization. However, the direct counts were 6 to 8 orders of magnitude greater, indicating that the vast majority of microbes present in the wastes were dead or non-cultivable. An additional indication that the HMC was sterilizing the wastes was the results from the added commercial spore test strips to the wastes prior to HMC operation. Nearly all could be recovered from the HMC disks post-operation and all were showed negative growth when run through the manufacturer's protocol, meaning that the 106 or so spores impregnated into the strips were dead. Control test strips, i.e., not exposed to the HMC conditions were all strongly positive. One area of concern is that the identities of isolates from the cultivable counts included several human pathogens, namely Staphylococcus aureus. The project reported here provides microbial characterization support to the Waste Management Systems element of the Life Support and Habitation Systems program.

In Vitro Wear Resistance of Nano-Hybrid Composite Denture Teeth.

PubMed

Munshi, Nabeel; Rosenblum, Marc; Jiang, Shuying; Flinton, Robert

2017-04-01

To evaluate the wear resistance of nano-hybrid composite denture teeth as compared to two commonly used denture teeth: interpenetrating polymer network (IPN) and double crosslinking polymethylmethacrylate (PMMA) denture teeth. 18 styli and 18 disk specimens were prepared from the three denture tooth materials: nano-hybrid composite, IPN, and double crosslinking PMMA. The specimens were mounted in a two-body wear testing machine to simulate chewing in the complete denture. The amount of wear from the styli specimens were measured before and after using a digital micrometer, and the depth of the wear track from the disk specimens was measured using a noncontact 3D optical profilometer. The total wear from each denture tooth group was compared using one-way ANOVA with a 0.05 significance level. A Tukey post hoc test was used to determine differences between the three groups. The mean total wear in the nano-hybrid composite teeth group was 1.16 mm, SD = 0.5 mm, statistically significantly higher (p ≤ 0.0001) than the IPN (mean = 0.13 mm, SD = 0.05) and double crosslinking PMMA tooth groups (mean = 0.31 mm, SD = 0.19). There was no statistically significant difference between IPN denture teeth and double crosslinking PMMA denture teeth in the amount of wear. Nano-hybrid composite denture teeth exhibited statistically significantly more wear than the IPN and double crosslinking PMMA denture teeth. © 2015 by the American College of Prosthodontists.

Comparing phototoxicity during the development of a zebrafish craniofacial bone using confocal and light sheet fluorescence microscopy techniques.

PubMed

Jemielita, Matthew; Taormina, Michael J; Delaurier, April; Kimmel, Charles B; Parthasarathy, Raghuveer

2013-12-01

The combination of genetically encoded fluorescent proteins and three-dimensional imaging enables cell-type-specific studies of embryogenesis. Light sheet microscopy, in which fluorescence excitation is provided by a plane of laser light, is an appealing approach to live imaging due to its high speed and efficient use of photons. While the advantages of rapid imaging are apparent from recent work, the importance of low light levels to studies of development is not well established. We examine the zebrafish opercle, a craniofacial bone that exhibits pronounced shape changes at early developmental stages, using both spinning disk confocal and light sheet microscopies of fluorescent osteoblast cells. We find normal and aberrant opercle morphologies for specimens imaged with short time intervals using light sheet and spinning disk confocal microscopies, respectively, under equivalent exposure conditions over developmentally-relevant time scales. Quantification of shapes reveals that the differently imaged specimens travel along distinct trajectories in morphological space. Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

The spiral-compact galaxy pair AM 2208-251: Computer simulations versus observations

NASA Technical Reports Server (NTRS)

Klaric, Mario; Byrd, Gene G.

1990-01-01

The system AM2208-251 is a roughly edge-on spiral extending east-west with a smaller round compact E system about 60 arcsec east of the spiral nucleus along the major axis of the spiral. Bertola, Huchtmeier, and Zeilinger (1990) have presented optical spectroscopic as well as single dish 21 cm observations of this system. Their spectroscopic data show, via emission lines lambda lambda 3727-29A, a rising rotation curve near the nucleus. These spectroscopic observations may indicate a tidal interaction in the system. In order to learn more about such pairs, the authors simulated the interaction using the computer model developed by Miller (1976 a,b, 1978) and modified by the authors (Byrd 1986, 1987, 1988). To do the simulation they need an idea of the mutual orbits of the two galaxies. Their computer model is a two-dimensional polar N-body program. It consists of a self-gravitating disk of particles, within an inert axially symmetric stabilizing halo potential. The particles are distributed in a 24(radial) by 36(azimuthal) polar grid. Self consistent calculations can be done only within the grid area. The disk is modeled with a finite Mestel disk, where all the particles initially move in circular orbits with constant tangential velocities (Mestel 1963), resulting in a flat rotation curve. The gas particles in the spiral's disk, which make up 30 percent of its mass, collide in the following manner. The number of particles in each bin of the polar grid is counted every time step. If it is greater than a given critical density, all the particles in the bin collide, obtaining in the result the same velocities, equal to the average for the bin. This process produces clumps of gas particles-the star formation sites. The authors suppress the collision in the inner part of the disk (within the circle r = 6) to represent the hole seen in the gas in the nuclear bulge of spirals. They thus avoid spurious effects due to collisions in that region. They also varied the size of the collisional bins, which did not affect their conclusions.

Mid-infrared interferometry towards the massive young stellar object CRL 2136: inside the dust rim

NASA Astrophysics Data System (ADS)

de Wit, W. J.; Hoare, M. G.; Oudmaijer, R. D.; Nürnberger, D. E. A.; Wheelwright, H. E.; Lumsden, S. L.

2011-02-01

Context. Establishing the importance of circumstellar disks and their properties is crucial to fully understand massive star formation. Aims: We aim to spatially resolve the various components that make-up the accretion environment of a massive young stellar object (⪉100 AU), and reproduce the emission from near-infrared to millimeter wavelengths using radiative transfer codes. Methods: We apply mid-infrared spectro-interferometry to the massive young stellar object CRL 2136. The observations were performed with the Very Large Telescope Interferometer and the MIDI instrument at a 42 m baseline probing angular scales of 50 milli-arcseconds. We model the observed visibilities in parallel with diffraction-limited images at both 24.5 μm and in the N-band (with resolutions of 0.6´´and 0.3´´, respectively), as well as the spectral energy distribution. Results: The arcsec-scale spatial information reveals the well-resolved emission from the dusty envelope. By simultaneously modelling the spatial and spectral data, we find that the bulk of the dust emission occurs at several dust sublimation radii (approximately 170 AU). This reproduces the high mid-infrared fluxes and at the same time the low visibilities observed in the MIDI data for wavelengths longward of 8.5 μm. However, shortward of this wavelength the visibility data show a sharp up-turn indicative of compact emission. We discuss various potential sources of this emission. We exclude a dust disk being responsible for the observed spectral imprint on the visibilities. A cool supergiant star and an accretion disk are considered and both shown to be viable origins of the compact mid-infrared emission. Conclusions: We propose that CRL 2136 is embedded in a dusty envelope, which truncates at several times the dust sublimation radius. A dust torus is manifest in the equatorial region. We find that the spectro-interferometric N-band signal can be reproduced by either a gaseous disk or a bloated central star. If the disk extends to the stellar surface, it accretes at a rate of 3.0 × 10-3 M⊙ yr-1. Based on observations with the VLTI, proposal 381.C-0607.

Effects of carbon and hafnium concentrations in wrought powder-metallurgy superalloys based on NASA 2B-11 alloy

NASA Technical Reports Server (NTRS)

Miner, R. V., Jr.

1976-01-01

A candidate alloy for advanced-temperature turbine engine disks, and four modifications of that alloy with various C and Hf concentrations were produced as cross-rolled disks from prealloyed powder that was hot isostatically compacted. The mechanical properties, microstructures, and phase relations of the alloys are discussed in terms of their C and Hf concentrations. A low-C and high-Hf modification of IIB-11 had the best balance of mechanical properties for service below about 750 C. Because of their finer grain sizes, none of the powder-metallurgy alloys produced had the high-temperature rupture strength of conventionally cast and wrought IIB-11.

Surface temperature determination in surface analytic systems by infrared optical pyrometry

NASA Technical Reports Server (NTRS)

Wheeler, Donald R.; Jones, William R., Jr.; Pepper, Stephen V.

1988-01-01

An IR pyrometric technique for measuring the surface temperatures of metal specimens in an ultrahigh-vacuum analytic chamber is described and demonstrated. The experimental setup comprises a commercial IR microscope with a long-working-distance right-angle objective (focal spot diameter 1 mm at 53 cm), a metal-coated glass vacuum chamber with a Ta-mesh-covered quartz viewport, an Mo specimen stub with an internal heating element, and a Ta disk test specimen with a flat side coated with a high-emissivity graphite film. The results of an initial calibration test are presented graphically and briefly characterized. The measurement error at 450 C is found to be less than 10 C.

The Influence of Soil Suction on the Shear Strength of Unsaturated Soil

DTIC Science & Technology

1990-09-01

the shear strength parameters c’ and 0’ for montmorillonitic and kaolinitic clays increased following the addition of divalent calcium hydroxide to...503-513. Sridharan, A., Rao, S.N., and Rao, G.V. (1971), "Shear Strength Char- acteristics of Saturated Montmorillonite and Kaolinite Clays," Soils...Summary of Shear Strengths of Unsaturated Specimens of Compacted Kaolinite and Compacted Red Earth (After Murthy, Sridharan and Nagaraj, 1987

Numerical calibration of the stable poisson loaded specimen

NASA Technical Reports Server (NTRS)

Ghosn, Louis J.; Calomino, Anthony M.; Brewer, Dave N.

1992-01-01

An analytical calibration of the Stable Poisson Loaded (SPL) specimen is presented. The specimen configuration is similar to the ASTM E-561 compact-tension specimen with displacement controlled wedge loading used for R-Curve determination. The crack mouth opening displacements (CMOD's) are produced by the diametral expansion of an axially compressed cylindrical pin located in the wake of a machined notch. Due to the unusual loading configuration, a three-dimensional finite element analysis was performed with gap elements simulating the contact between the pin and specimen. In this report, stress intensity factors, CMOD's, and crack displacement profiles are reported for different crack lengths and different contacting conditions. It was concluded that the computed stress intensity factor decreases sharply with increasing crack length, thus making the SPL specimen configuration attractive for fracture testing of brittle, high modulus materials.

Analytical stress intensity solution for the Stable Poisson Loaded specimen

NASA Technical Reports Server (NTRS)

Ghosn, Louis J.; Calomino, Anthony M.; Brewer, David N.

1993-01-01

An analytical calibration of the Stable Poisson Loaded (SPL) specimen is presented. The specimen configuration is similar to the ASTM E-561 compact-tension specimen with displacement controlled wedge loading used for R-curve determination. The crack mouth opening displacements (CMODs) are produced by the diametral expansion of an axially compressed cylindrical pin located in the wake of a machined notch. Due to the unusual loading configuration, a three-dimensional finite element analysis was performed with gap elements simulating the contact between the pin and specimen. In this report, stress intensity factors, CMODs, and crack displacement profiles, are reported for different crack lengths and different contacting conditions. It was concluded that the computed stress intensity factor decreases sharply with increasing crack length thus making the SPL specimen configuration attractive for fracture testing of brittle, high modulus materials.

The Novice User and CD-ROM Database Services. ERIC Digest.

ERIC Educational Resources Information Center

Schamber, Linda

This digest answers the following questions that beginning or novice users may have about CD-ROM (a compact disk with read-only memory) database services: (1) What is CD-ROM? (2) What databases are available? (3) Is CD-ROM difficult to use? (4) How much does CD-ROM cost? and (5) What is the future of CD-ROM? (15 references) (MES)

An Investigation into the Economics of Retrospective Conversion Using a CD-ROM System.

ERIC Educational Resources Information Center

Co, Francisca K.

This study compares the cost effectiveness of using a CD-ROM (compact disk read-only memory) system known as Bibliofile and the currently used OCLC (Online Computer Library Center)-based method to convert a university library's shelflist into a machine-readable database in the MARC (Machine-Readable Cataloging) format. The cost of each method of…

Compact ultrafast semiconductor disk laser: targeting GFP based nonlinear applications in living organisms

PubMed Central

Aviles-Espinosa, Rodrigo; Filippidis, George; Hamilton, Craig; Malcolm, Graeme; Weingarten, Kurt J.; Südmeyer, Thomas; Barbarin, Yohan; Keller, Ursula; Santos, Susana I.C.O; Artigas, David; Loza-Alvarez, Pablo

2011-01-01

We present a portable ultrafast Semiconductor Disk Laser (SDL) (or vertical extended cavity surface emitting laser—VECSELs), to be used for nonlinear microscopy. The SDL is modelocked using a quantum-dot semiconductor saturable absorber mirror (SESAM), delivering an average output power of 287 mW, with 1.5 ps pulses at 500 MHz and a central wavelength of 965 nm. Specifically, despite the fact of having long pulses and high repetition rates, we demonstrate the potential of this laser for Two-Photon Excited Fluorescence (TPEF) imaging of in vivo Caenorhabditis elegans (C. elegans) expressing Green Fluorescent Protein (GFP) in a set of neuronal processes and cell bodies. Efficient TPEF imaging is achieved due to the fact that this wavelength matches the peak of the two-photon action cross section of this widely used fluorescent marker. The SDL extended versatility is shown by presenting Second Harmonic Generation images of pharynx, uterus, body wall muscles and its potential to be used to excite other different commercial dyes. Importantly this non-expensive, turn-key, compact laser system could be used as a platform to develop portable nonlinear bio-imaging devices. PMID:21483599

Euler force actuation mechanism for siphon valving in compact disk-like microfluidic chips

PubMed Central

Deng, Yongbo; Fan, Jianhua; Zhou, Song; Zhou, Teng; Wu, Junfeng; Li, Yin; Liu, Zhenyu; Xuan, Ming; Wu, Yihui

2014-01-01

Based on the Euler force induced by the acceleration of compact disk (CD)-like microfluidic chip, this paper presents a novel actuation mechanism for siphon valving. At the preliminary stage of acceleration, the Euler force in the tangential direction of CD-like chip takes the primary place compared with the centrifugal force to function as the actuation of the flow, which fills the siphon and actuates the siphon valving. The Euler force actuation mechanism is demonstrated by the numerical solution of the phase-field based mathematical model for the flow in siphon valve. In addition, experimental validation is implemented in the polymethylmethacrylate-based CD-like microfluidic chip manufactured using CO2 laser engraving technique. To prove the application of the proposed Euler force actuation mechanism, whole blood separation and plasma extraction has been conducted using the Euler force actuated siphon valving. The newly introduced actuation mechanism overcomes the dependence on hydrophilic capillary filling of siphon by avoiding external manipulation or surface treatments of polymeric material. The sacrifice for highly integrated processing in pneumatic pumping technique is also prevented by excluding the volume-occupied compressed air chamber. PMID:24753736

The Circumstellar Disk and Asymmetric Outflow of the EX Lup Outburst System

NASA Astrophysics Data System (ADS)

Hales, A. S.; Pérez, S.; Saito, M.; Pinte, C.; Knee, L. B. G.; de Gregorio-Monsalvo, I.; Dent, B.; López, C.; Plunkett, A.; Cortés, P.; Corder, S.; Cieza, L.

2018-06-01

We present Atacama Large Millimeter/submillimeter Array (ALMA) observations at 0.″3 resolution of EX Lup, the prototype of the EXor class of outbursting pre-main-sequence stars. The circumstellar disk of EX Lup is resolved for the first time in 1.3 mm continuum emission and in the J = 2–1 spectral line of three isotopologues of CO. At the spatial resolution and sensitivity achieved, the compact dust continuum disk shows no indications of clumps, fragments, or asymmetries above the 5σ level. Radiative transfer modeling constrains the characteristic radius of the dust disk to 23 au and the total dust mass to 1.0 × 10‑4 M ⊙ (33 M ⊕), similar to other EXor sources. The 13CO and C18O line emissions trace the disk rotation and are used to constrain the disk geometry, kinematics, and a total gas disk mass of 5.1 × 10‑4 M ⊙. The 12CO emission extends out to a radius of 200 au and is asymmetric, with one side deviating from Keplerian rotation. We detect blueshifted, 12CO arc-like emission located 0.″8 to the northwest and spatially disconnected from the disk emission. We interpret this extended structure as the brightened walls of a cavity excavated by an outflow, which are more commonly seen in FUor sources. Such outflows have also been seen in the borderline FU/EXor object V1647 Ori, but not toward EXor objects. Our detection provides evidence that the outflow phenomenon persists into the EXor phase, suggesting that FUor and EXor objects are a continuous population in which outflow activity declines with age, with transitional objects such as EX Lup and V1647 Ori.

Strong disk winds traced throughout outbursts in black-hole X-ray binaries

NASA Astrophysics Data System (ADS)

Tetarenko, B. E.; Lasota, J.-P.; Heinke, C. O.; Dubus, G.; Sivakoff, G. R.

2018-02-01

Recurring outbursts associated with matter flowing onto compact stellar remnants (such as black holes, neutron stars and white dwarfs) in close binary systems provide a way of constraining the poorly understood accretion process. The light curves of these outbursts are shaped by the efficiency of angular-momentum (and thus mass) transport in the accretion disks, which has traditionally been encoded in a viscosity parameter, α. Numerical simulations of the magneto-rotational instability that is believed to be the physical mechanism behind this transport yield values of α of roughly 0.1–0.2, consistent with values determined from observations of accreting white dwarfs. Equivalent viscosity parameters have hitherto not been estimated for disks around neutron stars or black holes. Here we report the results of an analysis of archival X-ray light curves of 21 outbursts in black-hole X-ray binaries. By applying a Bayesian approach to a model of accretion, we determine corresponding values of α of around 0.2–1.0. These high values may be interpreted as an indication either of a very high intrinsic rate of angular-momentum transport in the disk, which could be sustained by the magneto-rotational instability only if a large-scale magnetic field threads the disk, or that mass is being lost from the disk through substantial outflows, which strongly shape the outburst in the black-hole X-ray binary. The lack of correlation between our estimates of α and the accretion state of the binaries implies that such outflows can remove a substantial fraction of the disk mass in all accretion states and therefore suggests that the outflows correspond to magnetically driven disk winds rather than thermally driven ones, which require specific radiative conditions.

Signs of Early-stage Disk Growth Revealed with ALMA

NASA Astrophysics Data System (ADS)

Yen, Hsi-Wei; Koch, Patrick M.; Takakuwa, Shigehisa; Krasnopolsky, Ruben; Ohashi, Nagayoshi; Aso, Yusuke

2017-01-01

We present ALMA 1.3 mm continuum, 12CO, C18O, and SO data for the Class 0 protostars Lupus 3 MMS, IRAS 15398-3559, and IRAS 16253-2429 at resolutions of ˜100 au. By measuring a rotational profile in C18O, a 100 au Keplerian disk around a 0.3 M⊙ protostar is observed in Lupus 3 MMS. No 100 au Keplerian disks are observed in IRAS 15398-3559 and IRAS 16253-2429. Nevertheless, embedded compact (<30 au) continuum components are detected. The C18O emission in IRAS 15398-3559 shows signatures of infall with a constant angular momentum. IRAS 16253-2429 exhibits signatures of infall and rotation, but its rotational profile is unresolved. By fitting the C18O data with our kinematic models, the protostellar masses and the disk radii are inferred to be 0.01 M⊙ and 20 au in IRAS 15398-3559, and 0.03 M⊙ and 6 au in IRAS 16253-2429. By comparing the specific angular momentum profiles from 10,000 au to 100 au in eight Class 0 and I protostars, we find that the evolution of envelope rotation can be described with conventional inside-out collapse models. In comparison with a sample of 18 protostars with known disk radii, our results reveal signs of disk growth, with the disk radius increasing as {{M}* }0.8+/- 0.14 or {t}1.09+/- 0.37 in the Class 0 stage, where M* is the protostellar mass and t is the age. The disk growth rate slows down in the Class I stage. In addition, we find a hint that the mass accretion rate declines as {t}-0.26+/- 0.04 from the Class 0 to the Class I stages.

Strong disk winds traced throughout outbursts in black-hole X-ray binaries.

PubMed

Tetarenko, B E; Lasota, J-P; Heinke, C O; Dubus, G; Sivakoff, G R

2018-02-01

Recurring outbursts associated with matter flowing onto compact stellar remnants (such as black holes, neutron stars and white dwarfs) in close binary systems provide a way of constraining the poorly understood accretion process. The light curves of these outbursts are shaped by the efficiency of angular-momentum (and thus mass) transport in the accretion disks, which has traditionally been encoded in a viscosity parameter, α. Numerical simulations of the magneto-rotational instability that is believed to be the physical mechanism behind this transport yield values of α of roughly 0.1-0.2, consistent with values determined from observations of accreting white dwarfs. Equivalent viscosity parameters have hitherto not been estimated for disks around neutron stars or black holes. Here we report the results of an analysis of archival X-ray light curves of 21 outbursts in black-hole X-ray binaries. By applying a Bayesian approach to a model of accretion, we determine corresponding values of α of around 0.2-1.0. These high values may be interpreted as an indication either of a very high intrinsic rate of angular-momentum transport in the disk, which could be sustained by the magneto-rotational instability only if a large-scale magnetic field threads the disk, or that mass is being lost from the disk through substantial outflows, which strongly shape the outburst in the black-hole X-ray binary. The lack of correlation between our estimates of α and the accretion state of the binaries implies that such outflows can remove a substantial fraction of the disk mass in all accretion states and therefore suggests that the outflows correspond to magnetically driven disk winds rather than thermally driven ones, which require specific radiative conditions.

Improving the oxidation resistance of 316L stainless steel in simulated pressurized water reactor primary water by electropolishing treatment

NASA Astrophysics Data System (ADS)

Han, Guangdong; Lu, Zhanpeng; Ru, Xiangkun; Chen, Junjie; Xiao, Qian; Tian, Yongwu

2015-12-01

The oxidation behavior of 316L stainless steel specimens after emery paper grounding, mechanical polishing, and electropolishing were investigated in simulated pressurized water reactor primary water at 310 °C for 120 and 500 h. Electropolishing afforded improved oxidation resistance especially during the early immersion stages. Duplex oxide films comprising a coarse Fe-rich outer layer and a fine Cr-rich inner layer formed on all specimens after 500 h of immersion. Only a compact layer was observed on the electropolished specimen after 120 h of immersion. The enrichment of chromium in the electropolished layer contributed to the passivity and protectiveness of the specimen.

Crack Branching and Fracture Mirror Data of Glasses and Advanced Ceramics

NASA Technical Reports Server (NTRS)

Choi, Sung R.; Gyekenyesi, John P.

1998-01-01

The fracture mirror and crack branching constants were determined from three glasses and nine advanced ceramics tested under various loading and specimen configurations in an attempt to use the constants as a data base for fractography. The ratios of fracture mirror or crack branching constant to fracture toughness were found to be approximately two for most ceramic materials tested. A demonstration of how to use the two constants as a tool for verifying stress measurements was presented for silicon nitride disk specimens subjected to high-temperature, constant stress-rate biaxial flexure testing.

A High-Velocity Collision With Our Galaxy's Disk

NASA Astrophysics Data System (ADS)

Kohler, Susanna

2016-08-01

What caused the newly discovered supershell in the outskirts of our galaxy? A new study finds evidence that a high-velocity cloud may have smashed into the Milky Ways disk millions of years ago.Mysterious Gas ShellsA single velocity-channel map of the supershell GS040.2+00.670, with red contours marking the high-velocity cloud at its center. [Adapted from Park et al. 2016]The neutral hydrogen gas that fills interstellar space is organized into structures like filaments, loops, and shells. Supershells are enormous shells of hydrogen gas that can have radii of a thousand light-years or more; weve spotted about 20 of these in our own galaxy, and more in nearby dwarfs and spiral galaxies.How do these structures form? One theory is that they result from several supernovae explosions occurring in the same area. But the energy needed to create a supershell is more than 3 x 1052 erg, which corresponds to over 30 supernovae quite a lot to have exploding in the same region.Theres an interesting alternative scenario: the supershells might instead be caused by the impacts of high-velocity clouds that fall into the galactic disk.Velocity data for the compact high-velocity cloud CHVC040. The cloud is moving fast enough to create the supershell observed. [Adapted from Park et al. 2016]The Milky Ways Speeding CloudsHigh-velocity clouds are clouds of mostly hydrogen that speed through the Milky Way with radial velocities that are very different from the material in the galactic disk. The origins of these clouds are unknown, but its proposed that they come from outside the galaxy they might be fragments of a nearby, disrupting galaxy, or they might have originated from flows of accreting gas in the space in between galaxies.Though high-velocity clouds have long been on the list of things that might cause supershells, weve yet to find conclusive evidence of this. But that might have just changed, with a recent discovery by a team of scientists led by Geumsook Park (Seoul National University).Using the Arecibo radio telescope in Puerto Rico, Park and collaborators have observed a supershell in the outskirts of the Milky Way and it has a high-velocity cloud at its center! Could this pair of objects be the evidence needed?A Revealing PairThe supershell, GS040.2+00.670, is roughly 3,000 light-years across, and its in the process of expanding outwards. The interior of the shell is filled with a complex structure that looks almost like spokes extending from a central hub. CHVC040, a compact high-velocity cloud, is located right at the central hub; the authors calculate a probability of less than a thousandth of a percent that this alignment is random.An integrated intensity map (click for a better look!) of neutral hydrogen showing the overall picture of the supershell (left), with the hub-and-spoke complex structure indicated within the shell. Contours in a close-up view (right) shows the location of the high-velocity cloud directly at the central hub. [Park et al. 2016]Park and collaborators examine the morphology and the velocity data for the shell and the cloud. Based on the authors calculations, if CHVC040 were traveling at a typical velocity for high-velocity clouds (several hundred kilometers per second), it would have enough energy to have created the supershell when it slammed into the disk. The parameters of the shell allow the authors estimate when the collision happened: roughly five million years ago.If this scenario is correct, Park and collaborators observations demonstrate that some compact high-velocity clouds can survive their trip through the galactic halo to smash into the galactic disk, forming a supershell on impact. A systematic study of the ~300 known compact high-velocity clouds in the Milky Way may reveal other, similar systems of compact high-velocity clouds coincident with supershells.CitationGeumsook Park et al 2016 ApJ 827 L27. doi:10.3847/2041-8205/827/2/L27

FEM simulation of the die compaction of pharmaceutical products: influence of visco-elastic phenomena and comparison with experiments.

PubMed

Diarra, Harona; Mazel, Vincent; Busignies, Virginie; Tchoreloff, Pierre

2013-09-10

This work studies the influence of visco-elastic behavior in the finite element method (FEM) modeling of die compaction of pharmaceutical products and how such a visco-elastic behavior may improve the agreement between experimental and simulated compression curves. The modeling of the process was conducted on a pharmaceutical excipient, microcrystalline cellulose (MCC), by using Drucker-Prager cap model coupled with creep behavior in Abaqus(®) software. The experimental data were obtained on a compaction simulator (STYLCAM 200R). The elastic deformation of the press was determined by performing experimental tests on a calibration disk and was introduced in the simulation. Numerical optimization was performed to characterize creep parameters. The use of creep behavior in the simulations clearly improved the agreement between the numerical and experimental compression curves (stresses, thickness), mainly during the unloading part of the compaction cycle. For the first time, it was possible to reproduce numerically the fact that the minimum tablet thickness is not obtained at the maximum compression stress. This study proves that creep behavior must be taken into account when modeling the compaction of pharmaceutical products using FEM methods. Copyright © 2013 Elsevier B.V. All rights reserved.

Kiloparsec-scale Dust Disks in High-redshift Luminous Submillimeter Galaxies

NASA Astrophysics Data System (ADS)

Hodge, J. A.; Swinbank, A. M.; Simpson, J. M.; Smail, I.; Walter, F.; Alexander, D. M.; Bertoldi, F.; Biggs, A. D.; Brandt, W. N.; Chapman, S. C.; Chen, C. C.; Coppin, K. E. K.; Cox, P.; Dannerbauer, H.; Edge, A. C.; Greve, T. R.; Ivison, R. J.; Karim, A.; Knudsen, K. K.; Menten, K. M.; Rix, H.-W.; Schinnerer, E.; Wardlow, J. L.; Weiss, A.; van der Werf, P.

2016-12-01

We present high-resolution (0.″16) 870 μm Atacama Large Millimeter/submillimeter Array (ALMA) imaging of 16 luminous ({L}{IR}˜ 4× {10}12 {L}⊙ ) submillimeter galaxies (SMGs) from the ALESS survey of the Extended Chandra Deep Field South. This dust imaging traces the dust-obscured star formation in these z˜ 2.5 galaxies on ˜1.3 kpc scales. The emission has a median effective radius of R e = 0.″24 ± 0.″02, corresponding to a typical physical size of {R}e= 1.8 ± 0.2 kpc. We derive a median Sérsic index of n = 0.9 ± 0.2, implying that the dust emission is remarkably disk-like at the current resolution and sensitivity. We use different weighting schemes with the visibilities to search for clumps on 0.″12 (˜1.0 kpc) scales, but we find no significant evidence for clumping in the majority of cases. Indeed, we demonstrate using simulations that the observed morphologies are generally consistent with smooth exponential disks, suggesting that caution should be exercised when identifying candidate clumps in even moderate signal-to-noise ratio interferometric data. We compare our maps to comparable-resolution Hubble Space Telescope {H}160-band images, finding that the stellar morphologies appear significantly more extended and disturbed, and suggesting that major mergers may be responsible for driving the formation of the compact dust disks we observe. The stark contrast between the obscured and unobscured morphologies may also have implications for SED fitting routines that assume the dust is co-located with the optical/near-IR continuum emission. Finally, we discuss the potential of the current bursts of star formation to transform the observed galaxy sizes and light profiles, showing that the z˜ 0 descendants of these SMGs are expected to have stellar masses, effective radii, and gas surface densities consistent with the most compact massive ({M}* ˜ 1-2 × 1011 {M}⊙ ) early-type galaxies observed locally.

Partially coherent lensfree tomographic microscopy⋄

PubMed Central

Isikman, Serhan O.; Bishara, Waheb; Ozcan, Aydogan

2012-01-01

Optical sectioning of biological specimens provides detailed volumetric information regarding their internal structure. To provide a complementary approach to existing three-dimensional (3D) microscopy modalities, we have recently demonstrated lensfree optical tomography that offers high-throughput imaging within a compact and simple platform. In this approach, in-line holograms of objects at different angles of partially coherent illumination are recorded using a digital sensor-array, which enables computing pixel super-resolved tomographic images of the specimen. This imaging modality, which forms the focus of this review, offers micrometer-scale 3D resolution over large imaging volumes of, for example, 10–15 mm3, and can be assembled in light weight and compact architectures. Therefore, lensfree optical tomography might be particularly useful for lab-on-a-chip applications as well as for microscopy needs in resource-limited settings. PMID:22193016

Effect of Magnesium Content and Processing Conditions on Phase Formation and Stability in Mg2+ δ Si0.3Sn0.7

NASA Astrophysics Data System (ADS)

Goyal, Gagan K.; Dasgupta, T.

2018-03-01

Mg2+ δ Si0.3Sn0.7 compositions with nominal Mg content of δ = 0, 0.2 are synthesized using a single-step quartz tube reaction method with different heating rates and holding times. The resulting powders are sintered using a uniaxial induction hot press under similar conditions to produce near-dense compacts. The effect of Mg content and processing conditions on the phase formation and its stability are studied using x-ray diffraction measurements, scanning electron microscopy (SEM) with elemental mapping and compositional analysis using energy dispersive spectroscopy (EDS). Results indicate that with sufficient Mg content and shorter synthesis time, the powder remains single phasic; however, prolonged heat treatment during synthesis results in Mg loss and causes the system to become biphasic. Compaction results in single-phase formation in all the specimens. This is attributed to the removal of the low-melting secondary Sn-rich phases present in the system. The decomposition of the specimens depends on the Mg content after the compaction step with a δ around - 0.15 necessary to preserve the single phase. The decomposition also results in Mg enrichment of the matrix (due to formation of elemental Sn), thereby acting as a self-healing mechanism. Annealing the dense products at 773 K for 24 h in static vacuum is carried out. Progressive Mg loss is observed resulting in degradation of the specimen.

Influences of Processing and Fatigue Cycling on Residual Stresses in a NiCrY-Coated Powder Metallurgy Disk Superalloy

NASA Astrophysics Data System (ADS)

Gabb, T. P.; Rogers, R. B.; Nesbitt, J. A.; Miller, R. A.; Puleo, B. J.; Johnson, D.; Telesman, J.; Draper, S. L.; Locci, I. E.

2017-11-01

Oxidation and corrosion can attack superalloy disk surfaces exposed to increasing operating temperatures in some turbine engine environments. Any potential protective coatings must also be resistant to harmful fatigue cracking during service. The objective of this study was to investigate how residual stresses evolve in one such coating. Fatigue specimens of a powder metallurgy-processed disk superalloy were coated with a NiCrY coating, shot peened, and then subjected to fatigue in air at room and high temperatures. The effects of this processing and fatigue cycling on axial residual stresses and other aspects of the coating were assessed. While shot peening did induce beneficial compressive residual stresses in the coating and substrate, these stresses relaxed in the coating with subsequent heating. Several cast alloys having compositions near the coating were subjected to thermal expansion and tensile stress relaxation tests to help explain this response of residual stresses in the coating. For the coated fatigue specimens, this response contributed to earlier cracking of the coating than for the uncoated surface during long intervals of cycling at 760 °C. Yet, substantial compressive residual stresses still remained in the substrate adjacent to the coating, which were sufficient to suppress fatigue cracking there. The coating continued to protect the substrate from hot corrosion pitting, even after fatigue cracks initiated in the coating.

Foreign Object Damage in Disks of Two Gas-turbine-grade Silicon Nitrides by Steel Ball Projectiles at Ambient Temperature

NASA Technical Reports Server (NTRS)

Choi, Sung R.; Pereira, J. Michael; Janosik, Lesley A.; Bhatt, Ramakrishna T.

2003-01-01

Foreign object damage (FOD) behavior of two commercial gas-turbine-grade silicon nitrides, AS800 and SN282, was determined at ambient temperature through postimpact strength testing of disks impacted by steel ball projectiles with a diameter of 1.59 mm in a velocity range from 115 to 440 m/s. AS800 silicon nitride exhibited a greater FOD resistance than SN282, primarily due to its greater value of fracture toughness (k(sub Ic)). The critical impact velocity V(sub c) for which the corresponding postimpact strength was the lowest was V(sub c) approximately equal to 440 and 300 m/s AS800 and SN282, respectively. A unique lower strength regime was typified for both silicon nitrides depending on impact velocity and was attributed to significant radial cracking. The damage generated by projectile impact was typically in the form of ring, radial, and cone cracks with their severity and combination being dependent on impact velocity. Unlike the thick (4 millimeters) flexure bar specimens used in our previous studies, the thin (2 millimeter) disk target specimen exhibited a unique back-side radial cracking on the reverse side just beneath the impact sites at and above impact velocities of 160 meters per second for SN282 and 220 meters per second AS800.

High energy power-law tail in X-ray binaries and bulk Comptonization due to an outflow from a disk

NASA Astrophysics Data System (ADS)

Kumar, Nagendra

2018-02-01

We study the high energy power-law tail emission of X-ray binaries (XRBs) by a bulk Comptonization process which is usually observed in the very high soft (VHS) state of black hole (BH) XRBs and the high soft (HS) state of the neutron star (NS) and BH XRBs. Earlier, to generate the power-law tail in bulk Comptonization framework, a free-fall converging flow into BH or NS had been considered as a bulk region. In this work, for a bulk region we consider mainly an outflow geometry from the accretion disk which is bounded by a torus surrounding the compact object. We have two choices for an outflow geometry: (i) collimated flow and (ii) conical flow of opening angle θ _b and the axis is perpendicular to the disk. We also consider an azimuthal velocity of the torus fluids as a bulk motion where the fluids are rotating around the compact object (a torus flow). We find that the power-law tail can be generated in a torus flow having large optical depth and bulk speed (>0.75 c), and in conical flow with θ _b > ˜ 30° for a low value of Comptonizing medium temperature. Particularly, in conical flow the low opening angle is more favourable to generate the power-law tail in both the HS state and the VHS state. We notice that when the outflow is collimated, then the emergent spectrum does not have power-law component for a low Comptonizing medium temperature.

Centrally Concentrated X-Ray Radiation from an Extended Accreting Corona in Active Galactic Nuclei

NASA Astrophysics Data System (ADS)

Liu, B. F.; Taam, Ronald E.; Qiao, Erlin; Yuan, Weimin

2017-10-01

The X-ray emission from bright active galactic nuclei (AGNs) is believed to originate in a hot corona lying above a cold, geometrically thin accretion disk. A highly concentrated corona located within ˜10 gravitational radii above the black hole is inferred from observations. Based on the accretion of interstellar medium/wind, a disk corona model has been proposed in which the corona is well coupled to the disk by radiation, thermal conduction, as well as by mass exchange. Such a model avoids artificial energy input to the corona and has been used to interpret the spectral features observed in AGN. In this work, it is shown that the bulk emission size of the corona is very small for the extended accretion flow in our model. More than 80% of the hard X-ray power is emitted from a small region confined within 10 Schwarzschild radii around a non-spinning black hole, which is expected to be even smaller accordingly for a spinning black hole. Here, the corona emission is more extended at higher Eddington ratios. The compactness parameter of the corona, l=\\tfrac{L}{R}\\tfrac{{σ }{{T}}}{{m}{{e}}{c}3}, is shown to be in the range of 1-33 for Eddington ratios of 0.02-0.1. Combined with the electron temperature in the corona, this indicates that electron-positron pair production is not dominant in this regime. A positive relation between the compactness parameter and photon index is also predicted. By comparing the above model predictions with observational features, we find that the model is in agreement with observations.

Strainrange partitioning behavior of an automotive turbine alloy

NASA Technical Reports Server (NTRS)

Annis, C. G.; Vanwanderham, M. C.; Wallace, R. M.

1976-01-01

This report addresses Strainrange Partitioning, an advanced life prediction analysis procedure, as applied to CA-101 (cast IN 792 + Hf), an alloy proposed for turbine disks in automotive gas turbine engines. The methodology was successful in predicting specimen life under thermal-mechanical cycling, to within a factor of + or - 2.

A novel dentin bond strength measurement technique using a composite disk in diametral compression.

PubMed

Huang, Shih-Hao; Lin, Lian-Shan; Rudney, Joel; Jones, Rob; Aparicio, Conrado; Lin, Chun-Pin; Fok, Alex

2012-04-01

New methods are needed that can predict the clinical failure of dental restorations that primarily rely on dentin bonding. Existing methods have shortcomings, e.g. severe deviation in the actual stress distribution from theory and a large standard deviation in the measured bond strength. We introduce here a novel test specimen by examining an endodontic model for dentin bonding. Specifically, we evaluated the feasibility of using the modified Brazilian disk test to measure the post-dentin interfacial bond strength. Four groups of resin composite disks which contained a slice of dentin with or without an intracanal post in the center were tested under diametral compression until fracture. Advanced nondestructive examination and imaging techniques in the form of acoustic emission (AE) and digital image correlation (DIC) were used innovatively to capture the fracture process in real time. DIC showed strain concentration first appearing at one of the lateral sides of the post-dentin interface. The appearance of the interfacial strain concentration also coincided with the first AE signal detected. Utilizing both the experimental data and finite-element analysis, the bond/tensile strengths were calculated to be: 11.2 MPa (fiber posts), 12.9 MPa (metal posts), 8.9 MPa (direct resin fillings) and 82.6 MPa for dentin. We have thus established the feasibility of using the composite disk in diametral compression to measure the bond strength between intracanal posts and dentin. The new method has the advantages of simpler specimen preparation, no premature failure, more consistent failure mode and smaller variations in the calculated bond strength. Copyright © 2012 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

Effect of target-fixture geometry on shock-wave compacted copper powders

NASA Astrophysics Data System (ADS)

Kim, Wooyeol; Ahn, Dong-Hyun; Yoon, Jae Ik; Park, Lee Ju; Kim, Hyoung Seop

2018-01-01

In shock compaction with a single gas gun system, a target fixture is used to safely recover a powder compact processed by shock-wave dynamic impact. However, no standard fixture geometry exists, and its effect on the processed compact is not well studied. In this study, two types of fixture are used for the dynamic compaction of hydrogen-reduced copper powders, and the mechanical properties and microstructures are investigated using the Vickers microhardness test and electron backscatter diffraction, respectively. With the assistance of finite element method simulations, we analyze several shock parameters that are experimentally hard to control. The results of the simulations indicate that the target geometry clearly affects the characteristics of incident and reflected shock waves. The hardness distribution and the microstructure of the compacts also show their dependence on the geometry. With the results of the simulations and the experiment, it is concluded that the target geometry affects the shock wave propagation and wave interaction in the specimen.

Manufacture of composite test specimens for delamination studies

NASA Technical Reports Server (NTRS)

Sumich, M.

1989-01-01

This paper describes the process for manufacturing high-quality test specimens for uses in evaluations of interlaminar tensile strength of laminated composites. The chosen specimen configuration is a curved beam which experiences interlaminar tension in the region of greatest curvature when the beam is subjected to 'opening' forces. The manufacturing process uses a lock-mold tooling approach, the principle of which relies upon the difference in coefficients of thermal expansion between the internal rubber mandrel and the surrounding steel female mold. With this method, compaction pressures above those provided by a typical autoclave can be achieved.

Optical information-processing systems and architectures II; Proceedings of the Meeting, San Diego, CA, July 9-13, 1990

NASA Astrophysics Data System (ADS)

Javidi, Bahram

The present conference discusses topics in the fields of neural networks, acoustooptic signal processing, pattern recognition, phase-only processing, nonlinear signal processing, image processing, optical computing, and optical information processing. Attention is given to the optical implementation of an inner-product neural associative memory, optoelectronic associative recall via motionless-head/parallel-readout optical disk, a compact real-time acoustooptic image correlator, a multidimensional synthetic estimation filter, and a light-efficient joint transform optical correlator. Also discussed are a high-resolution spatial light modulator, compact real-time interferometric Fourier-transform processors, a fast decorrelation algorithm for permutation arrays, the optical interconnection of optical modules, and carry-free optical binary adders.

Analysis Of Ultra Compact Ionized Hydrogen Regions Within The Northern Half Of The Galactic Disk

NASA Astrophysics Data System (ADS)

Bruce, John

2011-01-01

From a catalog of 199 candidate ultra compact (UC) HII regions 123 sources included in the the intersection of the GLIMPSE (8 μm),Cornish (6 cm), and Bolocam ( 1.1 mm) galactic plane surveys (BGPS) were analyzed. The sources were sorted based on 6 cm morphology and coincidence with 8 μm bubbles. The 1.1 mm flux attributes were measured and calculations were performed to determine the ionized hydrogen contributions to the 1.1 mm flux. The category averages and frequencies were obtained as well. Significant differences in HII percentages were present among the morphology groups but ranged widely, without apparent distinction, between the bubble forming and triggered source categories.

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

Murguia-Berthier, Ariadna; Ramirez-Ruiz, Enrico; Antoni, Andrea

During a common envelope (CE) episode in a binary system, the engulfed companion spirals to tighter orbital separations under the influence of drag from the surrounding envelope material. As this object sweeps through material with a steep radial gradient of density, net angular momentum is introduced into the flow, potentially leading to the formation of an accretion disk. The presence of a disk would have dramatic consequences for the outcome of the interaction because accretion might be accompanied by strong, polar outflows with enough energy to unbind the entire envelope. Without a detailed understanding of the necessary conditions for diskmore » formation during CE, therefore, it is difficult to accurately predict the population of merging compact binaries. This paper examines the conditions for disk formation around objects embedded within CEs using the “wind tunnel” formalism developed by MacLeod et al. We find that the formation of disks is highly dependent on the compressibility of the envelope material. Disks form only in the most compressible of stellar envelope gas, found in envelopes’ outer layers in zones of partial ionization. These zones are largest in low-mass stellar envelopes, but comprise small portions of the envelope mass and radius in all cases. We conclude that disk formation and associated accretion feedback in CE is rare, and if it occurs, transitory. The implication for LIGO black hole binary assembly is that by avoiding strong accretion feedback, CE interactions should still result in the substantial orbital tightening needed to produce merging binaries.« less

An ALMA and MagAO Study of the Substellar Companion GQ Lup B*

NASA Astrophysics Data System (ADS)

Wu, Ya-Lin; Sheehan, Patrick D.; Males, Jared R.; Close, Laird M.; Morzinski, Katie M.; Teske, Johanna K.; Haug-Baltzell, Asher; Merchant, Nirav; Lyons, Eric

2017-02-01

Multi-wavelength observations provide a complementary view of the formation of young, directly imaged planet-mass companions. We report the ALMA 1.3 mm and Magellan adaptive optics Hα, I\\prime , z\\prime , and Y S observations of the GQ Lup system, a classical T Tauri star with a 10{--}40 {M}{Jup} substellar companion at ˜110 au projected separation. We estimate the accretion rates for both components from the observed Hα fluxes. In our ˜0.″05 resolution ALMA map, we resolve GQ Lup A’s disk in the dust continuum, but no signal is found from the companion. The disk is compact, with a radius of ˜22 au, a dust mass of ˜6 M ⊕, an inclination angle of ˜56°, and a very flat surface density profile indicative of a radial variation in dust grain sizes. No gaps or inner cavity are found in the disk, so there is unlikely a massive inner companion to scatter GQ Lup B outward. Thus, GQ Lup B might have formed in situ via disk fragmentation or prestellar core collapse. We also show that GQ Lup A’s disk is misaligned with its spin axis, and possibly with GQ Lup B’s orbit. Our analysis on the tidal truncation radius of GQ Lup A’s disk suggests that GQ Lup B’s orbit might have a low eccentricity. This paper includes data gathered with the 6.5 m Magellan Clay Telescope at Las Campanas Observatory, Chile.

The Orbital Period of the SU Ursae Majoris Star EK Trianguli Australis and Evidence for Ring-Like Accretion Disks in Long-Supercycle Length SU Ursae Majoris Stars

NASA Astrophysics Data System (ADS)

Mennickent, Ronald E.; Arenas, Jose

1998-06-01

An orbital period of 0.06288(5) d has been found from a radial velocity study of the Hα emission line. In addition, we have detected an extra line emitting source located ~ 80(deg) apart from the vector joining the secondary--primary centers, as measured in the opposite sense to the binary rotational motion. This is not the expected location for the hotspot in dwarf novae. This anomaly could be removed by assuming a line emission lagging behind the white dwarf binary motion. In addition, we have estimated line emissivity (~ r(-alpha ) ) and disk radius (R equiv r_in/r_out) for 8 SU UMa stars. Most stars fit alpha = 1.8 +/- 0.1 but AK Cnc and WZ Sge strongly deviate from the mean; their emission line shapes can be explained assuming a post-outburst accretion disk mostly emitting close to the white dwarf (AK Cnc) and a ring-like disk (WZ Sge). In addition, we have found a tendency of long-supercycle length SU UMa stars to show very compact (large R; probably ring-like) accretion disks. If the supercycle length were basically controlled by the mass transfer rate (dot {M}), the inner disk radius would be a function of dot {M}. A white dwarf magnetic field ~ 5000 G is required to fit the truncation radius with the magnetosphere radius of SU UMa stars.

Formation of Giant Planets and Brown Dwarves

NASA Technical Reports Server (NTRS)

Lissauer, Jack J.

2003-01-01

According to the prevailing core instability model, giant planets begin their growth by the accumulation of small solid bodies, as do terrestrial planets. However, unlike terrestrial planets, the growing giant planet cores become massive enough that they are able to accumulate substantial amounts of gas before the protoplanetary disk dissipates. Models predict that rocky planets should form in orbit about most stars. It is uncertain whether or not gas giant planet formation is common, because most protoplanetary disks may dissipate before solid planetary cores can grow large enough to gravitationally trap substantial quantities of gas. Ongoing theoretical modeling of accretion of giant planet atmospheres, as well as observations of protoplanetary disks, will help decide this issue. Observations of extrasolar planets around main sequence stars can only provide a lower limit on giant planet formation frequency . This is because after giant planets form, gravitational interactions with material within the protoplanetary disk may cause them to migrat inwards and be lost to the central star. The core instability model can only produce planets greater than a few jovian masses within protoplanetary disks that are more viscous than most such disks are believed to be. Thus, few brown dwarves (objects massive enough to undergo substantial deuterium fusion, estimated to occur above approximately 13 jovian masses) are likely to be formed in this manner. Most brown dwarves, as well as an unknown number of free-floating objects of planetary mass, are probably formed as are stars, by the collapse of extended gas/dust clouds into more compact objects.

Evolutionary patterns of bone histology and bone compactness in xenarthran mammal long bones.

PubMed

Straehl, Fiona R; Scheyer, Torsten M; Forasiepi, Analía M; MacPhee, Ross D; Sánchez-Villagra, Marcelo R

2013-01-01

Bone microstructure reflects physiological characteristics and has been shown to contain phylogenetic and ecological signals. Although mammalian long bone histology is receiving increasing attention, systematic examination of the main clades has not yet been performed. Here we describe the long bone microstructure of Xenarthra based on thin sections representing twenty-two species. Additionally, patterns in bone compactness of humeri and femora are investigated. The primary bone tissue of xenarthran long bones is composed of a mixture of woven, parallel-fibered and lamellar bone. The vascular canals have a longitudinal, reticular or radial orientation and are mostly arranged in an irregular manner. Concentric rows of vascular canals and laminar organization of the tissue are only found in anteater bones. The long bones of adult specimens are marked by dense Haversian bone, a feature that has been noted for most groups of mammals. In the long bones of armadillos, secondary osteons have an oblique orientation within the three-dimensional bone tissue, thus resulting in their irregular shape when the bones are sectioned transversely. Secondary remodeling is generally more extensive in large taxa than in small taxa, and this could be caused by increased loading. Lines of arrested growth are assumed to be present in all specimens, but they are restricted to the outermost layer in bones of armadillos and are often masked by secondary remodeling in large taxa. Parameters of bone compactness show a pattern in the femur that separates Cingulata and Pilosa (Folivora and Vermilingua), with cingulates having a lower compactness than pilosans. In addition, cingulates show an allometric relationship between humeral and femoral bone compactness.

Anchoring Polar Magnetic Field in a Stationary Thick Accretion Disk

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

Samadi, Maryam; Abbassi, Shahram, E-mail: samadimojarad@um.ac.ir

We investigate the properties of a hot accretion flow bathed in a poloidal magnetic field. We consider an axisymmetric viscous-resistive flow in the steady-state configuration. We assume that the dominant mechanism of energy dissipation is due to turbulence viscosity and magnetic diffusivity. A certain fraction of that energy can be advected toward the central compact object. We employ the self-similar method in the radial direction to find a system of ODEs with just one varible, θ in the spherical coordinates. For the existence and maintenance of a purely poloidal magnetic field in a rotating thick disk, we find that themore » necessary condition is a constant value of angular velocity along a magnetic field line. We obtain an analytical solution for the poloidal magnetic flux. We explore possible changes in the vertical structure of the disk under the influences of symmetric and asymmetric magnetic fields. Our results reveal that a polar magnetic field with even symmetry about the equatorial plane makes the disk vertically thin. Moreover, the accretion rate decreases when we consider a strong magnetic field. Finally, we notice that hot magnetized accretion flows can be fully advected even in a slim shape.« less

Probing the Galactic Structure of the Milky Way with H II Regions

NASA Astrophysics Data System (ADS)

Red, Wesley Alexander; Wenger, Trey V.; Balser, Dana; Anderson, Loren; Bania, Thomas

2018-01-01

Mapping the structure of the Milky Way is challenging since we reside within the Galactic disk and distances are difficult to determine. Elemental abundances provide important constraints on theories of the formation and evolution of the Milky Way. HII regions are the brightest objects in the Galaxy at radio wavelengths and are detected across the entire Galactic disk. We use the Jansky Very Large Array (VLA) to observe the radio recombination line (RRL) and continuum emission of 120 Galactic HII regions located across the Galactic disk. In thermal equilibrium, metal abundances are expected to set the nebular electron temperature with high abundances producing low temperatures. We derive the metallicity of HII regions using an empirical relation between an HII region's radio recombination line-to-continuum ratio and nebular metallicity. Here we focus on a subset of 20 HII regions from our sample that have been well studied with the Green Bank Telescope (GBT) to test our data reduction pipeline and analysis methods. Our goal is to expand this study to the Southern skies with the Australia Telescope Compact Array and create a metallicity map of the entire Galactic disk.

Ultramassive (about 10 to the 11th solar mass) dark core in the luminous infrared galaxy NGC 6240?

NASA Technical Reports Server (NTRS)

Bland-Hawthorn, Jonathan; Wilson, Andrew S.; Tully, R. Brent

1991-01-01

The first complete kinematic maps for the superluminous IR galaxy NGC 6240 are reported. The data reveal two dynamical disks that exhibit radically different rotation and are closely spaced in velocity and position. One disk is roughly aligned with the major axis of the near-IR continuum and exhibits flat rotation out to about 20 arsec in radius, centered on the doubled nucleus seen at optical, near-IR, and radio wavelengths. The rotation turns over at r(t1) roughly 7.2 arcsec with a peak-to-peak velocity amplitude of roughly 280/sin i1 km/s, where i1 is the disk inclination. The rotation curve of the second disk comprises an unresolved or marginally resolved central velocity gradient with a peak-to-peak amplitude of roughly 800/sin i2 km/s within r(t2) of 2.5 arcsec, and a faster than Keplerian dropoff outside r(t2). The peak rotation implies a compact mass M2 greater than 4.5 x 10 to the 10th solar mass/sin-squared i2 within a radius of 1.2 kpc.

Grout compactness monitoring of concrete-filled fiber-reinforced polymer tube using electromechanical impedance

NASA Astrophysics Data System (ADS)

Shi, Yaokun; Luo, Mingzhang; Li, Weijie; Song, Gangbing

2018-05-01

The concrete-filled fiber-reinforced polymer tube (CFFT) is a type of structural element widely used in corrosive environments. Poor grout compactness results in incomplete contact or even no contact between the fiber-reinforced polymer (FRP) tube and the concrete grout, which reduces the load bearing capacity of a CFFT. The monitoring of grout compactness for CFFTs is important. The piezoceramic-based electromechanical impedance (EMI) method has emerged as an efficient and low-cost structural health monitoring technique. This paper presents a feasibility study using the EMI method to monitor grout compactness of CFFTs. In this research, CFFT specimens with different levels of compactness (empty, 1/5, 1/3, 1/2, 2/3, and full compactness) were prepared and subjected to EMI measurement by using four piezoceramic patches that were bonded circumferentially along the outer surface of the CFFT. To analyze the correlation between grout compactness and EMI signatures, a compactness index (CI) was proposed based on the root-mean-square deviation (RMSD). The experimental results show that the changes in admittance signatures are able to determine the grout compactness qualitatively. The proposed CI is able to effectively identify the compactness of the CFFT, and provides location information of the incomplete concrete infill.

Force-chain evolution in a two-dimensional granular packing compacted by vertical tappings

NASA Astrophysics Data System (ADS)

Iikawa, Naoki; Bandi, M. M.; Katsuragi, Hiroaki

2018-03-01

We experimentally study the statistics of force-chain evolution in a vertically-tapped two-dimensional granular packing by using photoelastic disks. In this experiment, the tapped granular packing is gradually compacted. During the compaction, the isotropy of grain configurations is quantified by measuring the deviator anisotropy derived from fabric tensor, and then the evolution of force-chain structure is quantified by measuring the interparticle forces and force-chain orientational order parameter. As packing fraction increases, the interparticle force increases and finally saturates to an asymptotic value. Moreover, the grain configurations and force-chain structures become isotropically random as the tapping-induced compaction proceeds. In contrast, the total length of force chains remains unchanged. From the correlations of those parameters, we find two relations: (i) a positive correlation between the isotropy of grain configurations and the disordering of force-chain orientations, and (ii) a negative correlation between the increasing of interparticle forces and the disordering of force-chain orientations. These relations are universally held regardless of the mode of particle motions with or without convection.

Balloon Exoplanet Nulling Interferometer (BENI)

NASA Technical Reports Server (NTRS)

Lyon, Richard G.; Clampin, Mark; Woodruff, Robert A.; Vasudevan, Gopal; Ford, Holland; Petro, Larry; Herman, Jay; Rinehart, Stephen; Carpenter, Kenneth; Marzouk, Joe

2009-01-01

We evaluate the feasibility of using a balloon-borne nulling interferometer to detect and characterize exosolar planets and debris disks. The existing instrument consists of a 3-telescope Fizeau imaging interferometer with 3 fast steering mirrors and 3 delay lines operating at 800 Hz for closed-loop control of wavefront errors and fine pointing. A compact visible nulling interferometer is under development which when coupled to the imaging interferometer would in-principle allow deep suppression of starlight. We have conducted atmospheric simulations of the environment above 100,000 feet and believe balloons are a feasible path forward towards detection and characterization of a limited set of exoplanets and their debris disks. Herein we will discuss the BENI instrument, the balloon environment and the feasibility of such as mission.

Microvax-based data management and reduction system for the regional planetary image facilities

NASA Technical Reports Server (NTRS)

Arvidson, R.; Guinness, E.; Slavney, S.; Weiss, B.

1987-01-01

Presented is a progress report for the Regional Planetary Image Facilities (RPIF) prototype image data management and reduction system being jointly implemented by Washington University and the USGS, Flagstaff. The system will consist of a MicroVAX with a high capacity (approx 300 megabyte) disk drive, a compact disk player, an image display buffer, a videodisk player, USGS image processing software, and SYSTEM 1032 - a commercial relational database management package. The USGS, Flagstaff, will transfer their image processing software including radiometric and geometric calibration routines, to the MicroVAX environment. Washington University will have primary responsibility for developing the database management aspects of the system and for integrating the various aspects into a working system.

A compact Nd:YAG DPSSL using diamond-cooled technology

NASA Astrophysics Data System (ADS)

Chou, Hsian P.; Wang, Yu-Lin; Hasson, Victor H.; Trainor, Daniel W.

2005-03-01

In our diamond-cooled approach, thin disks of laser gain material, e.g., Nd:YAG, are alternated between thin disks of single crystal synthetic diamond whose heat conductivity is over 2000 W/m-°K. The gain medium is face-pumped (along the optical axis) by the output of laser diode arrays. This optical configuration produces heat transfer from Nd:YAG to the diamond, in the direction of the optical axis, and then heat is rapidly conducted radially outward through the diamond to the cooling fluid circulating at the circumference of the diamond/YAG assembly. This geometry effectively removes the heat from the gain material in a manner that permits the attainment of high power output with excellent beam quality.

Origins of the elastic behavior of nanoparticle chain aggregates: Measurements using nanostructure manipulation device

NASA Astrophysics Data System (ADS)

Suh, Yong J.; Friedlander, Sheldon K.

2003-03-01

Nanoscale studies were conducted on the dynamic behavior of individual nanoparticle chain aggregates (NCAs) and their networks. For this purpose, device was fabricated to apply tension to NCA under controlled conditions. The device is composed of a specimen support and a cartridge. The specimen support is a deformable alloy disk with a narrow slit across which the NCAs are deposited; the cartridge is used to connect the specimen support to a specimen elongation support holder. The aggregates were stretched using the specimen holder to widen or narrow the slit gap at speeds from 0.5 to 300 nm/s and the motion was observed with a transmission electron microscope. Most of the studies were made with carbon NCA (primary particle size between 11 and 16 nm) generated by laser ablation of a graphite target. The aggregates were deposited on the specimen support (disk) to form bridges across the slit. When tension was applied, the NCA chains remained attached at the slit edges; the chains stretched as kinks on the scale of a few particle diameters were straightened by rotation and/or grain boundary sliding at particle-particle interfaces. After the chain became taut, increasing tension produced little additional extension. Eventually, the chain broke, the tension relaxed, and the elastically strained portions along the NCA recovered. This led to fast contraction of the two broken ends. In one of the cases studied in detail, a small primary particle in the chain doubled in length before the chain broke at this site. This probably occurred because of the high tensile stress in the small particle. In separate experiments, a network of carbon NCA was produced by increased deposition around the slit of a specimen support. Chains in the network broke successively as the network stretched. Some of the chains broke midway and not at the junctures with each other. They contracted fast showing behavior similar to that of the individual aggregates. Possible applications to the behavior of nanocomposite materials composed of blends of NCAs and molecular polymers (e.g., rubber) are described.

Enhancement of the wear resistance and microhardness of aluminum alloy by Nd:YaG laser treatment.

PubMed

Hussein, Haitham T; Kadhim, Abdulhadi; Al-Amiery, Ahmed A; Kadhum, Abdul Amir H; Mohamad, Abu Bakar

2014-01-01

Influence of laser treatment on mechanical properties, wear resistance, and Vickers hardness of aluminum alloy was studied. The specimens were treated by using Nd:YaG laser of energy 780 mj, wavelength 512 nm, and duration time 8 ns. The wear behavior of the specimens was studied for all specimens before and after treatment by Nd:YaG laser and the dry wear experiments were carried out by sing pinon-disc technique. The specimens were machined as a disk with diameter of 25 mm and circular groove in depth of 3 mm. All specimens were conducted by scanning electron microscopy (SEM), energy-dispersive X-ray fluorescence analysis (EDS), optical microscopy, and Vickers hardness. The results showed that the dry wear rate was decreased after laser hardening and increased Vickers hardness values by ratio of 2.4:1. The results showed that the values of wear rate for samples having circular grooves are less than samples without grooves after laser treatment.

Rapid virtual H&E histology of breast tissue specimens using a compact fluorescence nonlinear microscope

PubMed Central

Cahill, Lucas C.; Giacomelli, Michael G.; Yoshitake, Tadayuki; Vardeh, Hilde; Faulkner-Jones, Beverly E.; Connolly, James L.; Sun, Chi-Kuang; Fujimoto, James G.

2017-01-01

Up to 40% of patients undergoing breast conserving surgery for breast cancer require repeat surgeries due to close to or positive margins. The lengthy processing required for evaluating surgical margins by standard paraffin embedded histology precludes its use during surgery and therefore, technologies for rapid evaluation of surgical pathology could improve the treatment of breast cancer by reducing the number of surgeries required. We demonstrate real-time histological evaluation of breast cancer surgical specimens by staining specimens with acridine orange (AO) and sulforhodamine 101 (SR101) analogously to hematoxylin and eosin (H&E) and then imaging the specimens with fluorescence nonlinear microscopy (NLM) using a compact femtosecond fiber laser. A video-rate computational light absorption model was used to produce realistic virtual H&E images of tissue in real time and in three dimensions. NLM imaging could be performed to depths of 100 µm below the tissue surface, which is important since many surgical specimens require subsurface evaluation due to artifacts on the tissue surface from electrocautery, surgical ink or debris from specimen handling. We validate this method by expert review of NLM images compared to formalin fixed, paraffin embedded (FFPE) H&E histology. Diagnostically important features such as normal terminal ductal lobular units, fibrous and adipose stromal parenchyma, inflammation, invasive carcinoma, and in-situ lobular and ductal carcinoma were present in NLM images associated with pathologies identified on standard FFPE H&E histology. We demonstrate that AO and SR101 were extracted to undetectable levels after FFPE processing and fluorescence in situ hybridization (FISH) HER2 amplification status was unaffected by the NLM imaging protocol. This method potentially enables cost-effective, real-time histological guidance of surgical resections. PMID:29131161

COMPACT GALACTIC PLANETARY NEBULAE: AN HST /WFC3 MORPHOLOGICAL CATALOG, AND A STUDY OF THEIR ROLE IN THE GALAXY

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

Stanghellini, Letizia; Shaw, Richard A.; Villaver, Eva

We present the images of a Hubble Space Telescope ( HST /WFC3) snapshot program of angularly compact Galactic planetary nebulae (PNe), acquired with the aim of studying their size, evolutionary status, and morphology. PNe that are smaller than ∼4″ are underrepresented in most morphological studies, and today they are less well studied than their immediate evolutionary predecessors, the pre-planetary nebulae. The images have been acquired in the light of [O iii] λ 5007, which is commonly used to classify the PN morphology, in the UV continuum with the aim of detecting the central star unambiguously, and in the I -bandmore » to detect a cool stellar companion, if present. The sample of 51 confirmed PNe exhibits nearly the full range of primary morphological classes, with the distribution more heavily weighted toward bipolar PNe, but with the total of aspherical PNe almost identical to that of the general Galactic sample. A large range of microstructures is evident in our sample as well, with many nebulae displaying attached shells, halos, ansae, and internal structure in the form of arcs, rings, and spirals. Various aspherical structures in a few PNe, including detached arcs, suggest an interaction with the ISM. We studied the observed sample of compact Galactic PNe in the context of the general Galactic PN population, and explore whether their physical size, spatial distribution, reddening, radial metallicity gradient, and possible progenitors are peculiar within the population of Galactic PNe. We found that these compact Galactic PNe, which have been selected based on apparent dimensions, constitute a diverse Galactic PN population that is relatively uniformly distributed across the Galactic disk, including the outskirts of our Galaxy. This unique sample will be used in the future to probe the old Galactic disk population.« less

Binary Black Holes, Accretion Disks and Relativistic Jets: Photocenters of Nearby AGN and Quasars

NASA Technical Reports Server (NTRS)

Wehrle, Ann E.; Jones, Dayton L.; Meier, David L.; Piner, B. Glenn; Unwin, Stephen C.

2004-01-01

One of the most challenging questions in astronomy today is to understand the origin, structure, and evolution of the central engines in the nuclei of quasars and active galaxies (AGNs). The favoured theory involves the activation of relativistic jets from the fueling of a supermassive black hole through an accretion disk. In some AGN an outer optically thick, dusty torus is seen orbiting the black hole system. This torus is probably related to an inner accretion disk - black hole system that forms the actual powerhouse of the AGN. In radio-loud AGN two oppositely-directed radio jets are ejected perpendicular to the torus/disk system. Although there is a wealth of observational data on AGN, some very basic questions have not been definitively answered. The Space Interferometry Mission (SIM) will address the following three key questions about AGN. 1) Does the most compact optical emission from an AGN come from an accretion disk or from a relativistic jet? 2) Does the separation of the radio core and optical photocenter of the quasars used for the reference frame tie, change on the timescales of their photometric variability, or is the separation stable at the level of a few microarcseconds? 3) Do the cores of galaxies harbor binary supermassive black holes remaining from galaxy mergers? It is not known whether such mergers are common, and whether binaries would persist for a significant time.

Transport Phenomena in Thin Rotating Liquid Films Including: Nucleate Boiling

NASA Technical Reports Server (NTRS)

Faghri, Amir

2005-01-01

In this grant, experimental, numerical and analytical studies of heat transfer in a thin liquid film flowing over a rotating disk have been conducted. Heat transfer coefficients were measured experimentally in a rotating disk heat transfer apparatus where the disk was heated from below with electrical resistance heaters. The heat transfer measurements were supplemented by experimental characterization of the liquid film thickness using a novel laser based technique. The heat transfer measurements show that the disk rotation plays an important role on enhancement of heat transfer primarily through the thinning of the liquid film. Experiments covered both momentum and rotation dominated regimes of the flow and heat transfer in this apparatus. Heat transfer measurements have been extended to include evaporation and nucleate boiling and these experiments are continuing in our laboratory. Empirical correlations have also been developed to provide useful information for design of compact high efficiency heat transfer devices. The experimental work has been supplemented by numerical and analytical analyses of the same problem. Both numerical and analytical results have been found to agree reasonably well with the experimental results on liquid film thickness and heat transfer Coefficients/Nusselt numbers. The numerical simulations include the free surface liquid film flow and heat transfer under disk rotation including the conjugate effects. The analytical analysis utilizes an integral boundary layer approach from which

Why Are Some Galaxies Not Barred?

NASA Astrophysics Data System (ADS)

Saha, Kanak; Elmegreen, Bruce

2018-05-01

Although more than two-thirds of star-forming disk galaxies in the local universe are barred, some galaxies remain unbarred, occupying the upper half of the Hubble tuning fork diagram. Numerical simulations almost always produce bars spontaneously, so it remains a challenge to understand how galaxies sometimes prevent bars from forming. Using a set of collisionless simulations, we first reproduce the common result that cold stellar disks surrounding a classical bulge become strongly unstable to non-axisymmetric perturbations, leading to the rapid formation of spiral structure and bars. However, our analyses show that galaxy models with compact classical bulges (whose average density is greater than or comparable to the disk density calculated within bulge half-mass radii) are able to prevent bar formation for at least 4 Gyr even when the stellar disk is maximal and having low Toomre Q. Such bar prevention is the result of several factors such as (a) a small inner Lindblad resonance with a high angular rate, which contaminates an incipient bar with x 2 orbits, and (b) rapid loss of angular momentum accompanied by a rapid heating in the center from initially strong bar and spiral instabilities in a low-Q disk; in other words, a rapid initial rise to a value larger than ∼5 of the ratio of the random energy to the rotational energy in the central region of the galaxy.

A combined compensation method for the output voltage of an insulated core transformer power supply

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

Yang, L.; Yang, J., E-mail: jyang@mail.hust.edu.cn; Liu, K. F.

2014-06-15

An insulated core transformer (ICT) power supply is an ideal high-voltage generator for irradiation accelerators with energy lower than 3 MeV. However, there is a significant problem that the structure of the segmented cores leads to an increase in the leakage flux and voltage differences between rectifier disks. A high level of consistency in the output of the disks helps to achieve a compact structure by improving the utilization of both the rectifier components and the insulation distances, and consequently increase the output voltage of the power supply. The output voltages of the disks which are far away from themore » primary coils need to be improved to reduce their inhomogeneity. In this study, by investigating and comparing the existing compensation methods, a new combined compensation method is proposed, which increases the turns on the secondary coils and employs parallel capacitors to improve the consistency of the disks, while covering the entire operating range of the power supply. This method turns out to be both feasible and effective during the development of an ICT power supply. The non-uniformity of the output voltages of the disks is less than 3.5% from no-load to full-load, and the power supply reaches an output specification of 350 kV/60 mA.« less

A Unified Model for Tidal Disruption Events

NASA Astrophysics Data System (ADS)

Dai, Lixin; McKinney, Jonathan C.; Roth, Nathaniel; Ramirez-Ruiz, Enrico; Miller, M. Coleman

2018-06-01

In the past few years wide-field optical and UV transient surveys and X-ray telescopes have allowed us to identify a few dozen candidate tidal disruption events (TDEs). While in theory the physical processes in TDEs are ubiquitous, a few distinct classes of TDEs have been observed. Some TDEs radiate mainly in NUV/optical, while others produce prominent X-rays. Moreover, relativistic jets have been observed in only a handful of TDEs. This diversity might be related to the details of the super-Eddington accretion and emission physics relevant to TDE disks. In this Letter, we utilize novel three-dimensional general relativistic radiation magnetohydrodynamics simulations to study the super-Eddington compact disk phase expected in TDEs. Consistent with previous studies, geometrically thick disks, wide-angle optically thick fast outflows, and relativistic jets are produced. The outflow density and velocity depend sensitively on the inclination angle, and hence so does the reprocessing of emission produced from the inner disk. We then use Monte Carlo radiative transfer to calculate the reprocessed spectra and find that that the observed ratio of optical to X-ray fluxes increases with increasing inclination angle. This naturally leads to a unified model for different classes of TDEs in which the spectral properties of the TDE depend mainly on the viewing angle of the observer with respect to the orientation of the disk.

Dynamic J sub I-R Curve Testing of HY-130 Steel.

DTIC Science & Technology

1981-10-01

Society for Testing and Materials 0C Degrees Celsius COD Crack-opening displacement CT Compact tension CVN Charpy V-notch dia Diameter in-lb/in 2 Inch...inches per second. A key curve for HY-130 plate was developed under dynamic loading conditions using subsized compact specimens and was applied to...face grooves were machined along the crack line to a total section reduction of 20% with a standard Charpy V-notch (CVN) cutter (450 included angle

Heat transfer and pressure drop in a compact pin-fin heat exchanger with pin orientation at 18 deg to the flow direction

NASA Technical Reports Server (NTRS)

Olson, D. A.

1991-01-01

The heat transfer and pressure drop characteristics of a novel, compact heat exchanger in helium gas were measured at 3.5 MPa and Reynolds numbers of 450 to 12,000. The pin-fin specimen consisted of pins, 0.51 mm high and spaced 2.03 mm on centers, spanning a channel through which the helium flows; the angle of the row of pins to the flow direction was 18 deg. The specimen was radiatively heated on the top side at heat fluxes up to 74 W/sq cm and insulated on the back side. Correlations were developed for the friction factor and Nusselt number. The Nusselt number compares favorably to those of past studies of staggered pin-fins, when the measured temperatures are extrapolated to the temperature of the wall-fluid interface.

Tribological properties of Ag/Ti films on Al2O3 ceramic substrates

NASA Technical Reports Server (NTRS)

Dellacorte, Christopher; Pepper, Stephen V.; Honecy, Frank S.

1991-01-01

Ag solid lubricant films, with a thin Ti interlayer for enhanced adhesion, were sputter deposited on Al2O3 substrate disks to reduce friction and wear. The dual Ag/Ti films were tested at room temperature in a pin-on-disk tribometer sliding against bare, uncoated Al2O3 pins under a 4.9 N load at a sliding velocity of 1 m/s. The Ag/Ti films reduced the friction coefficient by 50 percent to about 0.41 compared to unlubricated baseline specimens. Pin wear was reduced by a factor of 140 and disk wear was reduced by a factor of 2.5 compared to the baseline. These films retain their good tribological properties including adhesion after heat treatments at 850 C and thus may be able to lubricate over a wide temperature range. This lubrication technique is applicable to space lubrication, advanced heat engines, and advanced transportation systems.

Combined reflection and transmission microscope for telemedicine applications in field settings.

PubMed

Biener, Gabriel; Greenbaum, Alon; Isikman, Serhan O; Lee, Kelvin; Tseng, Derek; Ozcan, Aydogan

2011-08-21

We demonstrate a field-portable upright and inverted microscope that can image specimens in both reflection and transmission modes. This compact and cost-effective dual-mode microscope weighs only ∼135 grams (<4.8 ounces) and utilizes a simple light emitting diode (LED) to illuminate the sample of interest using a beam-splitter cube that is positioned above the object plane. This LED illumination is then partially reflected from the sample to be collected by two lenses, creating a reflection image of the specimen onto an opto-electronic sensor-array that is positioned above the beam-splitter cube. In addition to this, the illumination beam is also partially transmitted through the same specimen, which then casts lensfree in-line holograms of the same objects onto a second opto-electronic sensor-array that is positioned underneath the beam-splitter cube. By rapid digital reconstruction of the acquired lensfree holograms, transmission images (both phase and amplitude) of the same specimen are also created. We tested the performance of this field-portable microscope by imaging various micro-particles, blood smears as well as a histopathology slide corresponding to skin tissue. Being compact, light-weight and cost-effective, this combined reflection and transmission microscope might especially be useful for telemedicine applications in resource limited settings. This journal is © The Royal Society of Chemistry 2011

The AU Mic Debris Disk: Far-infrared and Submillimeter Resolved Imaging

NASA Astrophysics Data System (ADS)

Matthews, Brenda C.; Kennedy, Grant; Sibthorpe, Bruce; Holland, Wayne; Booth, Mark; Kalas, Paul; MacGregor, Meredith; Wilner, David; Vandenbussche, Bart; Olofsson, Göran; Blommaert, Joris; Brandeker, Alexis; Dent, W. R. F.; de Vries, Bernard L.; Di Francesco, James; Fridlund, Malcolm; Graham, James R.; Greaves, Jane; Heras, Ana M.; Hogerheijde, Michiel; Ivison, R. J.; Pantin, Eric; Pilbratt, Göran L.

2015-10-01

We present far-infrared and submillimeter maps from the Herschel Space Observatory and the James Clerk Maxwell Telescope of the debris disk host star AU Microscopii. Disk emission is detected at 70, 160, 250, 350, 450, 500, and 850 μm. The disk is resolved at 70, 160, and 450 μm. In addition to the planetesimal belt, we detect thermal emission from AU Mic’s halo for the first time. In contrast to the scattered light images, no asymmetries are evident in the disk. The fractional luminosity of the disk is 3.9× {10}-4 and its milimeter-grain dust mass is 0.01 {M}\\oplus (±20%). We create a simple spatial model that reconciles the disk spectral energy distribution as a blackbody of 53 ± 2 K (a composite of 39 and 50 K components) and the presence of small (non-blackbody) grains which populate the extended halo. The best-fit model is consistent with the “birth ring” model explored in earlier works, i.e., an edge-on dust belt extending from 8.8 to 40 AU, but with an additional halo component with an {r}-1.5 surface density profile extending to the limits of sensitivity (140 AU). We confirm that AU Mic does not exert enough radiation force to blow out grains. For stellar mass-loss rates of 10-100 times solar, compact (zero porosity) grains can only be removed if they are very small; consistently with previous work, if the porosity is 0.9, then grains approaching 0.1 μm can be removed via corpuscular forces (i.e., the stellar wind).

Confronting Standard Models of Proto-planetary Disks with New Mid-infrared Sizes from the Keck Interferometer

NASA Astrophysics Data System (ADS)

Millan-Gabet, Rafael; Che, Xiao; Monnier, John D.; Sitko, Michael L.; Russell, Ray W.; Grady, Carol A.; Day, Amanda N.; Perry, R. B.; Harries, Tim J.; Aarnio, Alicia N.; Colavita, Mark M.; Wizinowich, Peter L.; Ragland, Sam; Woillez, Julien

2016-08-01

We present near- and mid-infrared (MIR) interferometric observations made with the Keck Interferometer Nuller and near-contemporaneous spectro-photometry from the infrared telescope facilities (IRTFs) of 11 well-known young stellar objects, several of which were observed for the first time in these spectral and spatial resolution regimes. With au-level spatial resolution, we first establish characteristic sizes of the infrared emission using a simple geometrical model consisting of a hot inner rim and MIR disk emission. We find a high degree of correlation between the stellar luminosity and the MIR disk sizes after using near-infrared data to remove the contribution from the inner rim. We then use a semi-analytical physical model to also find that the very widely used “star + inner dust rim + flared disk” class of models strongly fails to reproduce the spectral energy distribution (SED) and spatially resolved MIR data simultaneously; specifically a more compact source of MIR emission is required than results from the standard flared disk model. We explore the viability of a modification to the model whereby a second dust rim containing smaller dust grains is added, and find that the 2-rim model leads to significantly improved fits in most cases. This complexity is largely missed when carrying out SED modeling alone, although detailed silicate feature fitting by McClure et al. recently came to a similar conclusion. As has been suggested recently by Menu et al., the difficulty in predicting MIR sizes from the SED alone might hint at “transition disk”-like gaps in the inner au; however, the relatively high correlation found in our MIR disk size versus stellar luminosity relation favors layered disk morphologies and points to missing disk model ingredients instead.

CONFRONTING STANDARD MODELS OF PROTO-PLANETARY DISKS WITH NEW MID-INFRARED SIZES FROM THE KECK INTERFEROMETER

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

Millan-Gabet, Rafael; Che, Xiao; Monnier, John D.

We present near- and mid-infrared (MIR) interferometric observations made with the Keck Interferometer Nuller and near-contemporaneous spectro-photometry from the infrared telescope facilities (IRTFs) of 11 well-known young stellar objects, several of which were observed for the first time in these spectral and spatial resolution regimes. With au-level spatial resolution, we first establish characteristic sizes of the infrared emission using a simple geometrical model consisting of a hot inner rim and MIR disk emission. We find a high degree of correlation between the stellar luminosity and the MIR disk sizes after using near-infrared data to remove the contribution from the innermore » rim. We then use a semi-analytical physical model to also find that the very widely used “star + inner dust rim + flared disk” class of models strongly fails to reproduce the spectral energy distribution (SED) and spatially resolved MIR data simultaneously; specifically a more compact source of MIR emission is required than results from the standard flared disk model. We explore the viability of a modification to the model whereby a second dust rim containing smaller dust grains is added, and find that the 2-rim model leads to significantly improved fits in most cases. This complexity is largely missed when carrying out SED modeling alone, although detailed silicate feature fitting by McClure et al. recently came to a similar conclusion. As has been suggested recently by Menu et al., the difficulty in predicting MIR sizes from the SED alone might hint at “transition disk”-like gaps in the inner au; however, the relatively high correlation found in our MIR disk size versus stellar luminosity relation favors layered disk morphologies and points to missing disk model ingredients instead.« less

Experimental Study and Numerical Modeling of Fracture Propagation in Shale Rocks During Brazilian Disk Test

NASA Astrophysics Data System (ADS)

Mousavi Nezhad, Mohaddeseh; Fisher, Quentin J.; Gironacci, Elia; Rezania, Mohammad

2018-06-01

Reliable prediction of fracture process in shale-gas rocks remains one of the most significant challenges for establishing sustained economic oil and gas production. This paper presents a modeling framework for simulation of crack propagation in heterogeneous shale rocks. The framework is on the basis of a variational approach, consistent with Griffith's theory. The modeling framework is used to reproduce the fracture propagation process in shale rock samples under standard Brazilian disk test conditions. Data collected from the experiments are employed to determine the testing specimens' tensile strength and fracture toughness. To incorporate the effects of shale formation heterogeneity in the simulation of crack paths, fracture properties of the specimens are defined as spatially random fields. A computational strategy on the basis of stochastic finite element theory is developed that allows to incorporate the effects of heterogeneity of shale rocks on the fracture evolution. A parametric study has been carried out to better understand how anisotropy and heterogeneity of the mechanical properties affect both direction of cracks and rock strength.

Imipenem resistance in clinical Escherichia coli from Qom, Iran.

PubMed

Shams, Saeed; Hashemi, Ali; Esmkhani, Mohammad; Kermani, Somaye; Shams, Elham; Piccirillo, Alessandra

2018-05-18

The emergence of metallo-β-lactamase-producing Enterobacteriaceae is a worldwide health concern. In this study, the first evaluation of MBL genes, bla IMP and bla VIM , in Escherichia coli resistant to imipenem isolated from urine and blood specimens in Qom, Iran is described. Three hundred urine and blood specimens were analysed to detect the presence of E. coli. Resistance to imipenem and other antimicrobials was determined by disk diffusion and MIC. MBL production was screened using CDDT. PCR was also carried out to determine the presence of bla IMP and bla VIM genes in imipenem-resistant isolates. In total, 160 E. coli isolates were collected from March to May 2016. According to disk diffusion, high-level of resistance (20%) to cefotaxime was observed, whereas the lowest (1%) was detected for tetracycline. In addition, five isolates showed resistance to imipenem with a MIC ≥ 4 µg/mL. CDDT test confirmed that five isolates were MBL-producing strains, but no bla IMP and bla VIM genes were detected. Results of this study show a very low level of resistance to imipenem in our geographical area.

Strain-Life Assessment of Grainex Mar-M 247 for NASA's Turbine Seal Test Facility

NASA Technical Reports Server (NTRS)

Delgado, Irebert R.; Halford, Gary R.; Steinetz, Bruce M.; Rimnac, Clare M.

2004-01-01

NASA s Turbine Seal Test Facility is used to test air-to-air seals for use primarily in advanced jet engine applications. Combinations of high temperature, high speed, and high pressure limit the disk life, due to the concern of crack initiation in the bolt holes of the Grainex Mar-M 247 disk. The primary purpose of this current work is to determine an inspection interval to ensure safe operation. The current work presents high temperature fatigue strain-life data for test specimens cut from an actual Grainex Mar-M 247 disk. Several different strain-life models were compared to the experimental data including the Manson-Hirschberg Method of Universal Slopes, the Halford-Nachtigall Mean Stress Method, and the Modified Morrow Method. The Halford-Nachtigall Method resulted in only an 18 percent difference between predicted and experimental results. Using the experimental data at a 99.95 percent prediction level and the presence of 6 bolt holes it was found that the disk should be inspected after 665 cycles based on a total strain of 0.5 percent at 649 C.

Imaging intracellular protein dynamics by spinning disk confocal microscopy

PubMed Central

Stehbens, Samantha; Pemble, Hayley; Murrow, Lindsay; Wittmann, Torsten

2012-01-01

The palette of fluorescent proteins has grown exponentially over the last decade, and as a result live imaging of cells expressing fluorescently tagged proteins is becoming more and more main stream. Spinning disk confocal microscopy (SDC) is a high speed optical sectioning technique, and a method of choice to observe and analyze intracellular fluorescent protein dynamics at high spatial and temporal resolution. In an SDC system, a rapidly rotating pinhole disk generates thousands of points of light that scan the specimen simultaneously, which allows direct capture of the confocal image with low noise scientific grade cooled charged-coupled device (CCD) cameras, and can achieve frame rates of up 1000 frames per second. In this chapter we describe important components of a state-of-the-art spinning disk system optimized for live cell microscopy, and provide a rationale for specific design choices. We also give guidelines how other imaging techniques such as total internal reflection (TIRF) microscopy or spatially controlled photoactivation can be coupled with SDC imaging, and provide a short protocol on how to generate cell lines stably expressing fluorescently tagged proteins by lentivirus-mediated transduction. PMID:22264541

An elastic strip with multiple cracks and applications to tapered specimens

NASA Technical Reports Server (NTRS)

Liu, X.-H.; Erdogan, F.

1985-01-01

In this paper an infinite elastic strip containing arbitrarily oriented cracks and subjected to uniform tension and a pair of concentrated forces is formulated in terms of a system of singular integral equations. Even though the technique is sufficiently general to solve new multiple crack problem, with the objective of applying the results to tapered specimens, only a certain symmetric crack geometry and loading conditions are considered. The stress intensity factors are calculated for edge cracks in the strip under uniform tension and for a 'compact' and a 'slender' tapered specimen (the latter simulating the double cantilever beam) under concentrated forces or crack surface wedge forces.

Rapid viscosity measurements of powdered thermosetting resins

NASA Technical Reports Server (NTRS)

Price, H. L.; Burks, H. D.; Dalal, S. K.

1978-01-01

A rapid and inexpensive method of obtaining processing-related data on powdered thermosetting resins has been investigated. The method involved viscosity measurements obtained with a small specimen (less than 100 mg) parallel plate plastometer. A data acquisition and reduction system was developed which provided a value of viscosity and strain rate about 12-13 second intervals during a test. The effects of specimen compaction pressure and reduction of adhesion between specimen and parallel plates were examined. The plastometer was used to measure some processing-related viscosity changes of an addition polyimide resin, including changes caused by pre-test heat treatment, test temperature, and strain rate.

A comparative study of progressive wear of four dental monolithic, veneered glass-ceramics.

PubMed

Zhang, Zhenzhen; Yi, Yuanping; Wang, Xuesong; Guo, Jiawen; Li, Ding; He, Lin; Zhang, Shaofeng

2017-10-01

This study evaluated the wear performance and wear mechanisms of four dental glass-ceramics, based on the microstructure and mechanical properties in the progressive wear process. Bar (N = 40, n = 10) and disk (N = 32, n = 8) specimens were prepared from (A) lithium disilicate glass-ceramic (LD), (B) leucite reinforced glass-ceramic (LEU), (C) feldspathic glass-ceramic (FEL), and (D) fluorapatite glass-ceramic (FLU). The bar specimens were tested for three-point flexural strength, hardness, fracture toughness and elastic modulus. The disk specimens paired with steatite antagonists were tested in a pin-on-disk tribometer with 10N up to 1000,000 wear cycles. The wear analysis of glass-ceramics was performed using a 3D profilometer after every 200,000 wear cycles. Wear loss of steatite antagonists was calculated by measuring the weight and density using sensitive balance and Archimedes' method. Wear morphologies and microstructures were analyzed by scanning electron microscopy (SEM). The crystalline phase compositions were determined using X-ray diffraction (XRD). One-way analysis of variance (ANOVA) was used to analyze the data. Multiple pair-wise comparison of means was performed by Tukey's post-hoc test. LD showed the highest fracture toughness, flexural strength, elastic modulus and crystallinity, followed by LEU and FEL, and FLU showed the lowest. However, the hardness of LD was lower than all the other three types of ceramics. For steatite antagonists, LD produced the least wear loss of antagonist, followed by LEU and FEL, and FLU had the most wear loss. For glass-ceramic materials, LD exhibited similar wear loss as LEU, but more than FLU and FEL did. Moreover, fracture occurred on the wear surface of FLU. In the progressive wear process, veneering porcelains showed better wear resistance but fluorapatite veneering porcelains appeared fracture surface. Monolithic lithium disilicate glass-ceramics with higher mechanical properties showed more wear loss, however, they did not fracture and produced less wear loss of antagonists. Copyright © 2017 Elsevier Ltd. All rights reserved.

Effect of different dental ceramic systems on the wear of human enamel: An in vitro study.

PubMed

Zandparsa, Roya; El Huni, Rabie M; Hirayama, Hiroshi; Johnson, Marc I

2016-02-01

The wear of tooth structure opposing different advanced dental ceramic systems requires investigation. The purpose of this in vitro study was to compare the wear of advanced ceramic systems against human enamel antagonists. Four ceramic systems (IPS e.max Press, IPS e.max CAD, Noritake Super Porcelain EX-3, and LAVA Plus Zirconia) and 1 control group containing human enamel specimens were used in this study (n = 12). All specimens were fabricated as disks 11 mm in diameter and 3 mm thick. The mesiopalatal cusps of the maxillary third molars were prepared to serve as the enamel styluses. All specimens were embedded individually in 25 mm(3) autopolymerizing acrylic resin blocks. Wear was measured with a cyclic loading machine and a newly designed wear simulator. All enamel styluses (cusps) were scanned using the Activity 880 digital scanner (SmartOptics). Data from the base line and follow-up scans were collected and compared with Qualify 2012 3-dimensional (3D) and 2D digital inspection software (Geomagic), which aligned the models and detected the geometric changes and the wear caused by the antagonist specimen. One-way ANOVA was used to analyze the collected data. After 125,000 bidirectional loading cycles, the mean loss of opposing enamel volume for the enamel disks in the control group was 37.08 μm(3), the lowest mean value for IPS e.max Press system was 39.75 μm(3); 40.58 μm(3) for IPS e.max CAD; 45.08 μm(3) for Noritake Super Porcelain EX-3 system; and 48.66 μm(3) for the Lava Plus Zirconia system. No statically significant differences were found among the groups in opposing enamel volume loss (P=.225) or opposing enamel height loss (P=.149). In terms of opposing enamel height loss, Lava Plus Zirconia system showed the lowest mean value of 27.5 μm. The mean value for the IPS e.max CAD system was 27.91 μm; 29.08 μm for the control enamel; 33.25 μm for the IPS e.max Press system; and 34.75 μm for the Noritake Super Porcelain EX-3 system. Within the limitations of this in vitro study, no differences were found in the linear and volumetric reduction of enamel cusps abraded against enamel disks and all other ceramic specimens. All ceramic systems exhibited high durability and were wear-friendly to opposing enamel. Copyright © 2016 Editorial Council for the Journal of Prosthetic Dentistry. Published by Elsevier Inc. All rights reserved.

Evolutionary Patterns of Bone Histology and Bone Compactness in Xenarthran Mammal Long Bones

PubMed Central

Straehl, Fiona R.; Scheyer, Torsten M.; Forasiepi, Analía M.; MacPhee, Ross D.; Sánchez-Villagra, Marcelo R.

2013-01-01

Bone microstructure reflects physiological characteristics and has been shown to contain phylogenetic and ecological signals. Although mammalian long bone histology is receiving increasing attention, systematic examination of the main clades has not yet been performed. Here we describe the long bone microstructure of Xenarthra based on thin sections representing twenty-two species. Additionally, patterns in bone compactness of humeri and femora are investigated. The primary bone tissue of xenarthran long bones is composed of a mixture of woven, parallel-fibered and lamellar bone. The vascular canals have a longitudinal, reticular or radial orientation and are mostly arranged in an irregular manner. Concentric rows of vascular canals and laminar organization of the tissue are only found in anteater bones. The long bones of adult specimens are marked by dense Haversian bone, a feature that has been noted for most groups of mammals. In the long bones of armadillos, secondary osteons have an oblique orientation within the three-dimensional bone tissue, thus resulting in their irregular shape when the bones are sectioned transversely. Secondary remodeling is generally more extensive in large taxa than in small taxa, and this could be caused by increased loading. Lines of arrested growth are assumed to be present in all specimens, but they are restricted to the outermost layer in bones of armadillos and are often masked by secondary remodeling in large taxa. Parameters of bone compactness show a pattern in the femur that separates Cingulata and Pilosa (Folivora and Vermilingua), with cingulates having a lower compactness than pilosans. In addition, cingulates show an allometric relationship between humeral and femoral bone compactness. PMID:23874932

Evaluation of canal filling after using two warm vertical gutta-percha compaction techniques in vivo: a preliminary study.

PubMed

Venturi, M

2006-07-01

To evaluate the quality of root canal filling when comparing two warm gutta-percha filling techniques in vivo. Human teeth were randomly divided into two equal groups, with 30 canals each. The root canals were shaped by hand and ProFile 0.04 rotary instruments to size 20-40 at the end-point and then filled with gutta-percha cones and AH-Plus. In group A, a traditional warm vertical compaction technique was performed using the Touch'n Heat, and back-filling with the Obtura II. In group B, a modified warm vertical compaction technique was used: small amounts of gutta-percha were removed, and the remaining most apical 3 mm were compacted with a 1 mm movement; then thermomechanical back-filling was performed. The teeth were extracted, stored in dye, cleared, and the distance between the apex and apical limit of the filling, linear dye penetration, and voids were measured from the buccal, lingual, mesial and distal perspective. The homogeneity of variance and means was verified using Levene's test and t-test. ANOVA and Dunnett post hoc test were used to establish the significance and to analyse the effects through multiple comparisons. Compared with the specimens of group A, the specimens of group B exhibited less mean linear dye penetration (P < 0.05), smaller void length (P < or = 0.05) and maximal width (P < or = 0.05) when examined in all four views, and a more precise filling when viewed from the buccal aspect (P < 0.05). The modified warm vertical compaction technique with apical back-filling produced a more effective and precise three-dimensional filling.

Imaging a Central Ionized Component, a Narrow Ring, and the CO Snowline in the Multigapped Disk of HD 169142

NASA Astrophysics Data System (ADS)

Macías, Enrique; Anglada, Guillem; Osorio, Mayra; Torrelles, José M.; Carrasco-González, Carlos; Gómez, José F.; Rodríguez, Luis F.; Sierra, Anibal

2017-04-01

We report Very Large Array observations at 7 mm, 9 mm, and 3 cm toward the pre-transitional disk of the Herbig Ae star HD 169142. These observations have allowed us to study the millimeter emission of this disk with the highest angular resolution so far (0.″12 × 0.″09, or 14 au × 11 au, at 7 mm). Our 7 and 9 mm images show a narrow ring of emission at a radius of ˜25 au tracing the outer edge of the inner gap. This ring presents an asymmetric morphology that could be produced by dynamical interactions between the disk and forming planets. Additionally, the azimuthally averaged radial intensity profiles of the 7 and 9 mm images confirm the presence of the previously reported gap at ˜45 au and reveal a new gap at ˜85 au. We analyzed archival DCO+(3-2) and C18O(2-1) ALMA observations, showing that the CO snowline is located very close to this third outer gap. This suggests that growth and accumulation of large dust grains close to the CO snowline could be the mechanism responsible for this proposed outer gap. Finally, a compact source of emission is detected at 7 mm, 9 mm, and 3 cm toward the center of the disk. Its flux density and spectral index indicate that it is dominated by free-free emission from ionized gas, which could be associated with the photoionization of the inner disk, an independent object, or an ionized jet.

Can mixed star-plus-wormhole systems mimic black holes?

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

Dzhunushaliev, Vladimir; Folomeev, Vladimir; Kleihaus, Burkhard

We consider mixed strongly gravitating configurations consisting of a wormhole threaded by two types of ordinary matter. For such systems, the possibility of obtaining static spherically symmetric solutions describing compact massive central objects enclosed by high-redshift surfaces (black-hole-like configurations) is studied. Using the standard thin accretion disk model, we exhibit potentially observable differences allowing to distinguish the mixed systems from ordinary black holes with the same masses.

Reproductive and Hormonal Risk Factors for Breast Cancer in Blind Women

DTIC Science & Technology

2008-08-01

informational letters sent directly from the Perkins Braille and Talking Book Library in Watertown Massachusetts, the ACB and the Canadian National Institute...choice. Survey formats included via e-mail, website, compact disc, computer disk, audio tape, large print, Braille , in person, or verbally over the...survey data during telephone interviews or following receipt of written or audio surveys. Braille surveys were transcribed by a third party and

Analysis of User Need with CD-ROM Databases: A Case Study Based on Work Sampling at One University Library.

ERIC Educational Resources Information Center

Wells, Amy Tracy

Analysis of the needs of users of Compact Disk-Read Only Memory (CD-ROM) was performed at the Tampa campus of the University of South Florida. A review of the literature indicated that problems associated with selecting the appropriate database, searching, and requiring technical assistance were the probable areas of user need. The library has 17…

Kinematics of the inner thousand AU region around the young massive star AFGL 2591-VLA3: a massive disk candidate?

NASA Astrophysics Data System (ADS)

Wang, K.-S.; van der Tak, F. F. S.; Hogerheijde, M. R.

2012-07-01

Context. Recent detections of disks around young high-mass stars support the idea of massive star formation through accretion rather than coalescence, but the detailed kinematics in the equatorial region of the disk candidates is not well known, which limits our understanding of the accretion process. Aims: This paper explores the kinematics of the gas around a young massive star with millimeter-wave interferometry to improve our understanding of the formation of massive stars though accretion. Methods: We use Plateau de Bure interferometric images to probe the environment of the nearby (~1 kpc) and luminous (~20 000 L⊙) high-mass (10-16 M⊙) young star AFGL 2591-VLA3 in continuum and in lines of HDO, H_218O and SO2 in the 115 and 230 GHz bands. Radiative transfer calculations are employed to investigate the kinematics of the source. Results: At ~0.5″ (500 AU) resolution, the line images clearly resolve the velocity field of the central compact source (diameter of ~800 AU) and show linear velocity gradients in the northeast-southwest direction. Judging from the disk-outflow geometry, the observed velocity gradient results from rotation and radial expansion in the equatorial region of VLA3. Radiative transfer calculations suggest that the velocity field is consistent with sub-Keplerian rotation plus Hubble-law like expansion. The line profiles of the observed molecules suggest a layered structure, with HDO emission arising from the disk mid-plane, H_218O from the warm mid-layer, and SO2 from the upper disk. Conclusions: We propose AFGL 2591-VLA3 as a new massive disk candidate, with peculiar kinematics. The rotation of this disk is sub-Keplerian, probably due to magnetic braking, while the stellar wind may be responsible for the expansion of the disk. The expansion motion may also be an indirect evidence of disk accretion in the very inner region because of the conservation of angular momentum. The sub-Keplerian rotation discovered in our work suggests that AFGL 2591-VLA3 may be a special case linking transition of velocity field of massive disks from pure Keplerian rotation to solid-body rotation though definitely more new detections of circumstellar disks around high-mass YSOs are required to examine this hypothesis. Our results support the idea that early B-type stars could be formed with a circumstellar disk from the point of view of the disk-outflow geometry, though the accretion processes in the disk need to be further investigated.

Tetracycline impregnation affects degradation of porcine collagen matrix in healthy and diabetic rats.

PubMed

Tal, Haim; Weinreb, Miron; Shely, Asaf; Nemcovsky, Carlos E; Moses, Ofer

2016-07-01

The present study evaluated the degradation of collagen matrix (CM) immersed in tetracycline (TTC) or phosphate-buffered saline (PBS) in diabetic and normoglycemic rats. Diabetes was induced in 15 rats by systemic streptozotocin (STZ) (experimental); 15 healthy rats served as controls. One day before implantation 60 CM disks, 5 mm in diameter, were labeled with biotin: 30 were immersed in tetracycline (TTC) and 30 in PBS. One disk of each type was implanted subdermally in each rat. Animals were euthanized after 3 weeks, and tissue specimens containing the disks were prepared for histologic analysis. Horseradish peroxidase (HRP)-conjugated streptavidin was used to detect the remaining biotinylated collagen. Residual collagen area within the CM disks was analyzed and compared to baseline. Diabetes significantly increased the CM degradation. Immersion of the CM disks in a 50-mg/mL TTC solution before implantation decreased its degradation both in diabetic and normoglycemic rats. Diabetes significantly increases collagen matrix degradation; immersion of collagen matrix in TTC before implantation decreases its degradation in both diabetic and normoglycemic conditions. Immersion of medical collagen devices in TTC may be an effective means to decrease their resorption rate and increase their effectiveness, especially in situations with increased degradation such as diabetes.

Experimental compliance calibration of the compact fracture toughness specimen

NASA Technical Reports Server (NTRS)

Fisher, D. M.; Buzzard, R. J.

1980-01-01

Compliances and stress intensity coefficients were determined over crack length to width ratios from 0.1 to 0.8. Displacements were measured at the load points, load line, and crack mouth. Special fixturing was devised to permit accurate measurement of load point displacement. The results are in agreement with the currently used results of boundary collocation analyses. The errors which occur in stress intensity coefficients or specimen energy input determinations made from load line displacement measurements rather than from load point measurements are emphasized.

The effect of processing on autohesive strength development in thermoplastic resins and composites

NASA Technical Reports Server (NTRS)

Howes, Jeremy C.; Loos, Alfred C.; Hinkley, Jeffrey A.

1989-01-01

In the present investigation of processing effects on the autohesive bond strength of neat polysulfone resin and graphite-reinforced polysulfone-matrix composites measured resin bond strength development in precracked compact tension specimens 'healed' by heating over a contact period at a given temperature. The critical strain energy release rate of refractured composite specimens did not exhibit the strong time or temperature dependence of the neat resin tests; only 80-90 percent of the undamaged fracture energy is recoverable.

The influence of main bar corrosion on bond strength in selfcompacting concrete

NASA Astrophysics Data System (ADS)

Ayop, S. S.; Emhemed, A. N. K.; Jamaluddin, N.; Sadikin, A.

2017-11-01

The experimental study was conducted to determine the influence of main bar corrosion on bond strength in self-compacting concrete (SCC). A total 16 tension pullout tests specimens reinforced with 10 mm and 14 mm diameter bar were used for the bond strength test. The properties of SCC were determined from the slump flow, T50cm, V-funnel and L box test. Reinforcing bars in the concrete were submitted to impressed current to accelerate the corrosion of the bar. It was found that the relationship between bond strength and concrete strength in un-corroded specimens differed from that of corroded specimens set in high-strength concrete because of brittleness in the corroded specimens, which caused a sudden loss of bond strength. The results revealed that specimens of un-corroded and corroded showed a higher percentage of bond strength degradation during the pullout tests.

An Upgrade Pinning Block: A Mechanical Practical Aid for Fast Labelling of the Insect Specimens.

PubMed

Ghafouri Moghaddam, Mohammad Hossein; Ghafouri Moghaddam, Mostafa; Rakhshani, Ehsan; Mokhtari, Azizollah

2017-01-01

A new mechanical innovation is described to deal with standard labelling of dried specimens on triangular cards and/or pinned specimens in personal and public collections. It works quickly, precisely, and easily and is very useful for maintaining label uniformity in collections. The tools accurately sets the position of labels in the shortest possible time. This tools has advantages including rapid processing, cost effectiveness, light weight, and high accuracy, compared to conventional methods. It is fully customisable, compact, and does not require specialist equipment to assemble. Conventional methods generally require locating holes on the pinning block surface when labelling with a resulting risk to damage of the specimens. Insects of different orders can be labelled by this simple and effective tool.

An Upgrade Pinning Block: A Mechanical Practical Aid for Fast Labelling of the Insect Specimens

PubMed Central

Ghafouri Moghaddam, Mohammad Hossein; Rakhshani, Ehsan; Mokhtari, Azizollah

2017-01-01

Abstract A new mechanical innovation is described to deal with standard labelling of dried specimens on triangular cards and/or pinned specimens in personal and public collections. It works quickly, precisely, and easily and is very useful for maintaining label uniformity in collections. The tools accurately sets the position of labels in the shortest possible time. This tools has advantages including rapid processing, cost effectiveness, light weight, and high accuracy, compared to conventional methods. It is fully customisable, compact, and does not require specialist equipment to assemble. Conventional methods generally require locating holes on the pinning block surface when labelling with a resulting risk to damage of the specimens. Insects of different orders can be labelled by this simple and effective tool. PMID:29104440

Influence of Crack-Tip Configurations on the Fracture Response of 0.04-Inch Thick 2024-T3 Aluminum Alloy Sheet

NASA Technical Reports Server (NTRS)

Johnston, William M.; Newman, James C. (Technical Monitor)

2002-01-01

A series of fracture tests were conducted on Middle-crack tension M(T) and compact tension C(T) specimens to determine the effects of specimen type, specimen width, notch tip sharpness and buckling on the fracture behavior of cracked thin sheet (0.04 inch thick) 2024-T3 aluminum alloy material. A series of M(T) specimens were tested with three notch tip configurations: (1) a fatigue pre-cracked notch, (2) a 0.010-inch-diameter wire electrical discharge machined (EDM) notch, and (3) a EDM notch sharpened with a razor blade. The test procedures are discussed and the experimental results for failure stress, load vs. crack extension and the material stress-strain response are reported.

High-energy radiation from the relativistic jet of Cygnus X-3

NASA Astrophysics Data System (ADS)

Cerutti, B.; Dubus, G.; Henri, G.

2010-12-01

Cygnus X-3 is an accreting high-mass X-ray binary composed of a Wolf-Rayet star and an unknown compact object, possibly a black hole. The gamma-ray space telescope Fermi found definitive evidence that high-energy emission is produced in this system. We propose a scenario to explain the GeV gamma-ray emission in Cygnus X-3. In this model, energetic electron-positron pairs are accelerated at a specific location in the relativistic jet, possibly related to a recollimation shock, and upscatter the stellar photons to high energies. The comparison with Fermi observations shows that the jet should be inclined close to the line of sight and pairs should not be located within the system. Energetically speaking, a massive compact object is favored. We report also on our investigations of the gamma-ray absorption of GeV photons with the radiation emitted by a standard accretion disk in Cygnus X-3. This study shows that the gamma-ray source should not lie too close to the compact object.

The effects of redshifts and focusing on the spectrum of an accretion disk in the galactic center black hole candidate Sagittarius A(sup *)

NASA Technical Reports Server (NTRS)

Hollywood, J. M.; Melia, Fulvio

1995-01-01

There are firm indications that Sgr A(sup *), a compact, nonthermal radio source at the Galactic center, may be powered by the dissipation of gravitational energy as gas trapped from an ambient wind descends down the potential well, first through a quasi-spherical inflow (extending out to approximately 3 x 10(exp 16) cm) and then through a small accretion disk at less than or approximately = 5-10 Schwarzschild radii. Earlier three-dimensional Bondi-Hoyle numerical simulations have indicated that fluctuations in the accreted specific angular momentum can lead to a variability in the disk flux on a timescale of years. With greatly improved flux measurements at K and H, and the hint of a approximately 10 minute modulation in the IR luminosity, it is crucial to model the disk emission much more precisely than has been attempted thus far. In this Letter we take into account the effects of Doppler and gravitational redshifts, the light-travel time factor, and the light bending near the black hole to determine the measurable spectrum of Sgr A(sup *) in the increasingly important 10(exp 13) Hz less than or approximately = v less than or approximately = 10(exp 16) Hz frequency range. We find that the relativistic disk spectrum is much softer than its Newtonian counterpart, with a predicted UV flux roughly an order of magnitude smaller than had previously been anticipated. In addition, we find that when the physical conditions in the disk are taken to be consistent with the properties of the quasi-spherical infall (specifically, in terms of the accretion rate and disk size), only a slowly spinning or Schwarzschild black hole appears to fit the observations. Our calculations also reveal that the disk flux is much more weakly dependent on the observer's inclination angle than had been suspected on the basis of earlier Newtonian estimates.

Quantitative acoustic emission monitoring of fatigue cracks in fracture critical steel bridges.

DOT National Transportation Integrated Search

2014-01-01

The objective of this research is to evaluate the feasibility to employ quantitative acoustic : emission (AE) techniques for monitoring of fatigue crack initiation and propagation in steel : bridge members. Three A36 compact tension steel specimens w...

High Temperature, Slow Strain Rate Forging of Advanced Disk Alloy ME3

NASA Technical Reports Server (NTRS)

Gabb, Timothy P.; OConnor, Kenneth

2001-01-01

The advanced disk alloy ME3 was designed in the HSR/EPM disk program to have extended durability at 1150 to 1250 F in large disks. This was achieved by designing a disk alloy and process producing balanced monotonic, cyclic, and time-dependent mechanical properties. combined with robust processing and manufacturing characteristics. The resulting baseline alloy, processing, and supersolvus heat treatment produces a uniform, relatively fine mean grain size of about ASTM 7, with as-large-as (ALA) grain size of about ASTM 3. There is a long term need for disks with higher rim temperature capabilities than 1250 F. This would allow higher compressor exit (T3) temperatures and allow the full utilization of advanced combustor and airfoil concepts under development. Several approaches are being studied that modify the processing and chemistry of ME3, to possibly improve high temperature properties. Promising approaches would be applied to subscale material, for screening the resulting mechanical properties at these high temperatures. n obvious path traditionally employed to improve the high temperature and time-dependent capabilities of disk alloys is to coarsen the grain size. A coarser grain size than ASTM 7 could potentially be achieved by varying the forging conditions and supersolvus heat treatment. The objective of this study was to perform forging and heat treatment experiments ("thermomechanical processing experiments") on small compression test specimens of the baseline ME3 composition, to identify a viable forging process allowing significantly coarser grain size targeted at ASTM 3-5, than that of the baseline, ASTM 7.

The Circumstellar Environment of Low Mass Star Forming Regions

NASA Technical Reports Server (NTRS)

Butner, Harold M.

1999-01-01

The final technical report of the NASA grant project is presented. The goals of the grant were to: (1) analyze the data from the Far-Infrared (FIR) Camera on board the Kuiper Airborne Observatory (KAO); (2) acquire additional data at other wavelengths for models and (4) to develop source models for the Young stellar objects (YSOs)under study. The complete Spectral Energy Distribution (SED) from 10 microns out to 1.3 mm for all sources being studied have been obtained. The FIR imaging data was processed to reveal the maximum angular resolution possible, which allows us to model the disk. To model the disk we have the high resolution millimeter interferometry data. In summary the results to date are: (1) the vast majority of embedded YSOs in Taurus are compact at 100 microns. The models mos consistent with our data and other observations are either dominated by disk emissions, or envelopes that have relatively steep density gradients; (2) the submillimeter/millimeter photometer suggests that models are very successful. Disk emission plays an important role and must be considered when predicting the overall emission. (3) in the two cases, where we seem to have extended emission, we have to investigate other possible source models than a Shu collapse.

General Relativistic Effects and QPOs in X-Ray Binaries

NASA Astrophysics Data System (ADS)

Markovic, D.; Lamb, F. K.

We have investigated whether general relativistic effects may be responsible for some of the quasi-periodic X-ray brightness oscillations (QPOs) observed in low-mass binary systems containing accreting neutron stars and black hole candidates. In particular, we have computed the motions of accreting gas in the strong gravitational fields near such objects and have explored possible mechanisms for producing X-ray flux oscillations. We have discovered a family of weakly damped global gravitomagnetic (Lense-Thirring) warping modes of the inner (viscous) accretion disk that have precession frequencies ranging up to the single-particle gravitomagnetic precession frequency at the inner edge of the disk, which is about 30 Hz if the disk extends inward to the innermost stable circular orbit around a compact object of solar mass with dimensionless angular momentum cJ/GM2 ~ 0.2. Precession of regions of enhanced viscous dissipation or modulation of the accretion flow by the precession may produce observable periodic variation of the X-ray flux. Detectable effects might also be produced if the gas in the inner disk breaks up into a collection of distinct clumps. We have analyzed the dynamics of such clumps as well as the conditions required for their formation and survival on time scales long enough to produce QPOs with the coherence observed in low-mass X-ray binaries.

Fullerenes and disk-fullerenes

NASA Astrophysics Data System (ADS)

Deza, M.; Dutour Sikirić, M.; Shtogrin, M. I.

2013-08-01

A geometric fullerene, or simply a fullerene, is the surface of a simple closed convex 3-dimensional polyhedron with only 5- and 6-gonal faces. Fullerenes are geometric models for chemical fullerenes, which form an important class of organic molecules. These molecules have been studied intensively in chemistry, physics, crystallography, and so on, and their study has led to the appearance of a vast literature on fullerenes in mathematical chemistry and combinatorial and applied geometry. In particular, several generalizations of the notion of a fullerene have been given, aiming at various applications. Here a new generalization of this notion is proposed: an n-disk-fullerene. It is obtained from the surface of a closed convex 3-dimensional polyhedron which has one n-gonal face and all other faces 5- and 6-gonal, by removing the n-gonal face. Only 5- and 6-disk-fullerenes correspond to geometric fullerenes. The notion of a geometric fullerene is therefore generalized from spheres to compact simply connected two-dimensional manifolds with boundary. A two-dimensional surface is said to be unshrinkable if it does not contain belts, that is, simple cycles consisting of 6-gons each of which has two neighbours adjacent at a pair of opposite edges. Shrinkability of fullerenes and n-disk-fullerenes is investigated. Bibliography: 87 titles.

The Extreme Spin of the Black Hole in Cygnus X-1

NASA Technical Reports Server (NTRS)

Gou, Lijun; McClintock, Jeffre E.; Reid, Mark J.; Orosz, Jerome A.; Steiner, James F.; Narayan, Ramesh; Xiang, Jingen; Remillard, Ronald A.; Arnaud, Keith A.; Davis, Shane W.

2005-01-01

The compact primary in the X-ray binary Cygnus X-1 was the first black hole to be established via dynamical observatIOns. We have recently determined accurate values for its mass and distance, and for the orbital inclination angle of the binary. Building on these.results, which are based on our favored (asynchronous) dynamical model, we have measured the radius of the inner edge of the black hole's accretion disk by fitting its thermal continuum.spectrum to a fully relativistic model of a thin accretion disk. Assuming that the spin axis of the black hole is aligned with the orbital angular momentum vector, we have determined that Cygnus X-I contains a near-extreme Kerr black hole with a spin parameter a* > 0.95 (3(sigma)). For a less probable (synchronous) dynamIcal model, we find a* > 0.92 (3(sigma)). In our analysis, we include the uncertainties in black hole mass orbital inclination angle and distance, and we also include the uncertainty in the calibration of the absolute flux via the Crab. These four sources of uncertainty totally dominate the error budget. The uncertainties introduced by the thin-disk model we employ are particularly small in this case given the extreme spin of the black hole and the disk's low luminosity.

Saturn’s Formation and Early Evolution at the Origin of Jupiter’s Massive Moons

NASA Astrophysics Data System (ADS)

Ronnet, T.; Mousis, O.; Vernazza, P.; Lunine, J. I.; Crida, A.

2018-05-01

The four massive Galilean satellites are believed to have formed within a circumplanetary disk during the last stages of Jupiter’s formation. While the existence of a circum-Jovian disk is supported by hydrodynamic simulations, no consensus exists regarding the origin and delivery mechanisms of the building blocks of the forming satellites. The opening of a gap in the circumsolar disk would have efficiently isolated Jupiter from the main sources of solid material. However, a reservoir of planetesimals should have existed at the outer edge of Jupiter’s gap, where solids were trapped and accumulated over time. Here we show that the formation of Saturn’s core within this reservoir, or its prompt inward migration, allows planetesimals to be redistributed from this reservoir toward Jupiter and the inner Solar System, thereby providing enough material to form the Galilean satellites and to populate the Main Belt with primitive asteroids. We find that the orbit of planetesimals captured within the circum-Jovian disk are circularized through friction with gas in a compact system comparable to the current radial extent of the Galilean satellites. The decisive role of Saturn in the delivery mechanism has strong implications for the occurrence of massive moons around extrasolar giant planets as they would preferentially form around planets within multiple planet systems.

Use of a novel tunable solid state disk laser as a diagnostic system for laser-induced fluorescence

NASA Astrophysics Data System (ADS)

Paa, Wolfgang; Triebel, Wolfgang

2004-09-01

An all solid state disk laser system-named "Advanced Disk Laser (ADL)" -particularly tailored for laser induced fluorescence (LIF) in combustion processes is presented. The system currently under development comprises an Yb:YAG-seedlaser and a regenerative amplifier. Both are based on the disk laser concept as a new laser architecture. This allows a tunable, compact, efficient diode pumped solid state laser (DPSSL) system with repetition rates in the kHz region. After frequency conversion to the UV-spectral region via third and fourth harmonics generation, this laser-due to its unique properties such as single-frequency operation, wavelength tuneability and excellent beam profile-is well suited for excitation of small molecules such as formaldehyde, OH, NO or O2, which are characteristic for combustion processes. Using the method of planar laser induced fluorescence (PLIF) we observed concentration distributions of formaldehyde in cool and hot flames of a specially designed diethyl-ether burner. The images recorded with 1 kHz repetition rate allow visualizing the distribution of formaldehyde on a 1 ms time scale. This demonstrates for the first time the usability of this novel laser for LIF measurements and is the first step towards integration of the ADL into capsules for drop towers and the international space station.

The Extreme Spin of the Black Hole in Cygnus X-1

NASA Technical Reports Server (NTRS)

Gou, Lijun; McClintock, Jeffrey E.; Reid, Mark J.; Orosz, Jerome A.; Steiner, James F.; Narayan, Ramesh; Xiang, Jingen; Remillard, Ronald A.; Arnaud, Keith A.; Davis, Shane W.

2011-01-01

The compact primary in the X-ray binary Cygnus X-1 was the first black hole to be established via dynamical observations. We have recently determined accurate values for its mass and distance, and for the orbital inclination angle of the binary. Building on these results, which are based on our favored (asynchronous) dynamical model, we have measured the radius of the inner edge of the black hole s accretion disk by fitting its thermal continuum spectrum to a fully relativistic model of a thin accretion disk. Assuming that the spin axis of the black hole is aligned with the orbital angular momentum vector, we have determined that Cygnus X-1 contains a near-extreme Kerr black hole with a spin parameter a* > 0.95 (3(sigma)). For a less probable (synchronous) dynamical model, we find a. > 0.92 (3 ). In our analysis, we include the uncertainties in black hole mass, orbital inclination angle, and distance, and we also include the uncertainty in the calibration of the absolute flux via the Crab. These four sources of uncertainty totally dominate the error budget. The uncertainties introduced by the thin-disk model we employ are particularly small in this case given the extreme spin of the black hole and the disk s low luminosity.

Temperature effect on mechanical and tribological characterization of Mg-SiC nanocomposite fabricated by high rate compaction

NASA Astrophysics Data System (ADS)

Majzoobi, G. H.; Rahmani, K.; Atrian, A.

2018-01-01

In this paper, dynamic compaction is employed to produce Mg-SiC nanocomposite samples using a mechanical drop hammer. Different volume fractions of SiC nano reinforcement and magnesium (Mg) micron-size powder as the matrix are mechanically milled and consolidated at different temperatures. It is found that with the increase of temperature the sintering requirements is satisfied and higher quality samples are fabricated. The density, hardness, compressive strength and the wear resistance of the compacted specimens are characterized in this work. It was found that by increasing the content of nano reinforcement, the relative density of the compacted samples decreases, whereas, the micro-hardness and the strength of the samples enhance. Furthermore, higher densification temperatures lead to density increase and hardness reduction. Additionally, it is found that the wear rate of the nanocomposite is increased remarkably by increasing the SiC nano reinforcement.

General Relativistic Effects and QPOs in X-Ray Binaries

NASA Astrophysics Data System (ADS)

Markovic, D.; Lamb, F.

1999-05-01

We have investigated whether general relativistic effects may be responsible for some of the quasi-periodic X-ray brightness oscillations (QPOs) with frequencies 20--300 Hz observed in low-mass binary systems containing accreting neutron stars and black hole candidates. In particular, we have computed the motions of accreting gas in the strong gravitational fields near such objects and have explored possible mechanisms for producing X-ray flux oscillations. We have discovered a family of global gravitomagnetic (Lense-Thirring) warping modes of the inner accretion disk that have precession frequencies ranging up to the single-particle gravitomagnetic precession frequency at the inner edge of the disk, which is 30 Hz if the disk extends inward to the innermost stable circular orbit around a compact object of solar mass with dimensionless angular momentum cJ/GM2 0.2. The highest-frequency warping modes are very localized spiral corrugations of the inner disk and are weakly damped, with Q values 2--50. Precession of regions of enhanced viscous dissipation or modulation of the accretion flow by the precession may produce observable periodic variation of the X-ray flux. Detectable effects might also be produced if the gas in the inner disk breaks up into a collection of distinct clumps. We have analyzed the dynamics of such clumps as well as the conditions required for their formation and survival on time scales long enough to produce oscillations with the coherence observed in X-ray binaries.

The origin of the scatter of the star forming main sequence at z=0

NASA Astrophysics Data System (ADS)

Shanahan, Clare; Somerville, Rachel S.; Saintonge, Amelie; Huang, Mei-Ling

2016-01-01

We investigate the origin of the dispersion in the relationship between star formation rate (SFR) and stellar mass, known as the star forming main sequence (SFMS). Our study includes predictions from a state-of-the-art semi-analytic model (SAM) as well as observations from the COLDGASS, Bluedisk, and GAMA surveys. Using a simple toy model we demonstrate that, in the absence of a correlation between gas fraction and galaxy size, we would expect more compact disks to live 'high' on the SFMS, and vice versa, due to the observational Kennicutt relation. We demonstrate that this correlation is not seen in the observations, nor is it predicted by the SAM. We find in both the model and the observations that extended disks have a higher fraction of their baryonic mass in total cold gas and in HI and $H_{2}$ gas separately, offsetting the dependence of SFR on disk size. We investigate the origin of the gas fraction-size correlation in the SAMs, and find that it is connected with the rate of cosmological accretion of gas from the intergalactic medium.

The Role Of Rejuvenation In Shaping The High-Mass End Of The Main Sequence

NASA Astrophysics Data System (ADS)

Mancini, Chiara

2017-06-01

We investigate the nature of star forming galaxies with reduced specific SFRs and high stellar masses, those that seemingly cause the so-called bending of the main sequence. The fact that such objects host large bulges recently lead some to suggest that the internal formation of the bulges, via compaction or disk instabilities, was the late event that induced sSFRs of massive galaxies to drop in a slow downfall and thus the main sequence to bend. We have studied in detail a sample of 16 galaxies at 0.5

Development of a base mix design procedure.

DOT National Transportation Integrated Search

1974-01-01

This paper reports an investigation into the development of a compaction procedure for base mixes containing aggregates of 1 1/2" (38 mm) maximum size. The specimens were made in a manner similar to that given in ASTM Designation 1561-71, except that...

Friction management on Kansas Department of Transportation highways : technical summary.

DOT National Transportation Integrated Search

2017-04-01

The objectives of this study are to evaluate the performance of a local aggregate in HFST and to evaluate : the 3-dimensional laser profiler for measuring pavement texture. Slab specimens of hot-mix asphalt : (HMA) were compacted in the laboratory an...

An evaluation of the moisture susceptibility of warm mix asphalt mixtures.

DOT National Transportation Integrated Search

2010-05-01

This paper describes the results of a laboratory study conducted to evaluate the influence of Aspha-min and Sasobit : additives on the behaviour of warm asphalt mixtures. Specimens were compacted at two temperatures, 100 and 1458C, and : were sub...

Computer applications in diagnostic imaging.

PubMed

Horii, S C

1991-03-01

This article has introduced the nature, generation, use, and future of digital imaging. As digital technology has transformed other aspects of our lives--has the reader tried to buy a conventional record album recently? almost all music store stock is now compact disks--it is sure to continue to transform medicine as well. Whether that transformation will be to our liking as physicians or a source of frustration and disappointment is dependent on understanding the issues involved.

Identification of 1.4 Million Active Galactic Nuclei In the Mid-Infrared Using WISE Data

DTIC Science & Technology

2015-11-01

galaxies – infrared: stars – galaxies : active – quasars: general Supporting material: machine-readable table 1. INTRODUCTION The International Celestial...AGN-dominated galaxies , optical emission is thought to originate from the compact accretion disk surrounding the supermassive black hole (SMBH), while... galaxies , an optical centroid can be shifted relative to the radio position because of contamination from the host galaxy . Depending on the distance to

A mechanical property and stress corrosion evaluation of VIM-ESR-VAR work strengthened and direct double aged Inconel 718 bar material

NASA Technical Reports Server (NTRS)

Montano, J. W.

1986-01-01

Presented are the mechanical properties and the stress corrosion resistance of triple melted vacuum induction melted (VIM), electro-slag remelted (ESR), and vacuum arc remelted (VAR), solution treated, work strengthened and direct double aged Inconel 718 alloy bars 4.00 in. (10.16) and 5.75 in. (14.60 cm) diameter. Tensile, charpy v-notched impact, and compact tension specimens were tested at ambient temperature in both the longitudinal and transverse directions. Longitudinal tensile and yield strengths in excess of 220 ksi (1516.85 MPa) and 200 ksi (1378.00 MPa) respectively, were realized at ambient temperature. Additional charpy impact and compact tension tests were performed at -100 F (-73 C). Longitudinal charpy impact strength equalled or exceeded 12.0 ft-lbs (16.3 Joules) at ambient and at -100 F(-73 C) while longitudinal compact (LC) tension fracture toughness strength remained above 79 ksi (86.80 MPa) at ambient and at -100 F(-73 C) temperatures. No failures occurred in the longitudinal or transverse tensile specimens stressed to 75 and 100 percent of their respective yield strengths and exposed to a salt fog environment for 180 days. Tensile tests performed after the stress corrosion test indicated no mechanical property degradation.

Fracture Response Enhancement Of Aluminum Using In-Situ Selective Reinforcement

NASA Technical Reports Server (NTRS)

Abada, Christopher H.; Farley, Gary L.; Hyer, Michael W.

2006-01-01

A computer-based parametric study of the effect of reinforcement architectures on fracture response of aluminum compact-tension (CT) specimens is performed. Eleven different reinforcement architectures consisting of rectangular and triangular cross-section reinforcements were evaluated. Reinforced specimens produced between 13 and 28 percent higher fracture load than achieved with the unreinforced case. Reinforcements with blunt leading edges (rectangular reinforcements) exhibited superior performance relative to the triangular reinforcements with sharp leading edges. Relative to the rectangular reinforcements, the most important architectural feature was reinforcement thickness. At failure, the reinforcements carried between 58 and 85 percent of the load applied to the specimen, suggesting that there is considerable load transfer between the base material and the reinforcement.

Analysis of fatigue, fatique-crack propagation, and fracture data. [design of metallic aerospace structural components

NASA Technical Reports Server (NTRS)

Jaske, C. E.; Feddersen, C. E.; Davies, K. B.; Rice, R. C.

1973-01-01

Analytical methods have been developed for consolidation of fatigue, fatigue-crack propagation, and fracture data for use in design of metallic aerospace structural components. To evaluate these methods, a comprehensive file of data on 2024 and 7075 aluminums, Ti-6A1-4V, and 300M and D6Ac steels was established. Data were obtained from both published literature and unpublished reports furnished by aerospace companies. Fatigue and fatigue-crack-propagation analyses were restricted to information obtained from constant-amplitude load or strain cycling of specimens in air at room temperature. Fracture toughness data were from tests of center-cracked tension panels, part-through crack specimens, and compact-tension specimens.

Enhancement of the Wear Resistance and Microhardness of Aluminum Alloy by Nd:YaG Laser Treatment

PubMed Central

Hussein, Haitham T.; Kadhim, Abdulhadi; Al-Amiery, Ahmed A.; Kadhum, Abdul Amir H.; Mohamad, Abu Bakar

2014-01-01

Influence of laser treatment on mechanical properties, wear resistance, and Vickers hardness of aluminum alloy was studied. The specimens were treated by using Nd:YaG laser of energy 780 mj, wavelength 512 nm, and duration time 8 ns. The wear behavior of the specimens was studied for all specimens before and after treatment by Nd:YaG laser and the dry wear experiments were carried out by sing pinon-disc technique. The specimens were machined as a disk with diameter of 25 mm and circular groove in depth of 3 mm. All specimens were conducted by scanning electron microscopy (SEM), energy-dispersive X-ray florescence analysis (EDS), optical microscopy, and Vickers hardness. The results showed that the dry wear rate was decreased after laser hardening and increased Vickers hardness values by ratio of 2.4 : 1. The results showed that the values of wear rate for samples having circular grooves are less than samples without grooves after laser treatment. PMID:25136694

Comparison of Intralaminar and Interlaminar Mode-I Fracture Toughness of Unidirectional IM7/8552 Graphite/Epoxy Composite

NASA Technical Reports Server (NTRS)

Czabaj, Michael W.; Ratcliffe, James

2012-01-01

The intralaminar and interlaminar mode-I fracture-toughness of a unidirectional IM7/8552 graphite/epoxy composite were measured using compact tension (CT) and double cantilever beam (DCB) test specimens, respectively. Two starter crack geometries were considered for both the CT and DCB specimen configurations. In the first case, starter cracks were produced by 12.5 micron thick, Teflon film inserts. In the second case, considerably sharper starter cracks were produced by fatigue precracking. For each specimen configuration, use of the Teflon film starter cracks resulted in initially unstable crack growth and artificially high initiation fracture-toughness values. Conversely, specimens with fatigue precracks exhibited stable growth onset and lower initiation fracture toughness. For CT and DCB specimens with fatigue precracks, the intralaminar and interlaminar initiation fracture toughnesses were approximately equal. However, during propagation, the CT specimens exhibited more extensive fiber bridging, and rapidly increasing R-curve behavior as compared to the DCB specimens. Observations of initiation and propagation of intralaminar and interlaminar fracture, and the measurements of fracture toughness, were supported by fractographic analysis using scanning electron microscopy.

Three dimensional finite-element analysis of finite-thickness fracture specimens

NASA Technical Reports Server (NTRS)

Raju, I. S.; Newman, J. C., Jr.

1977-01-01

The stress-intensity factors for most of the commonly used fracture specimens (center-crack tension, single and double edge-crack tension, and compact), those that have a through-the-thickness crack, were calculated using a three dimensional finite-element elastic stress analysis. Three-dimensional singularity elements were used around the crack front. The stress intensity factors along the crack front were evaluated by using a force method, developed herein, that requires no prior assumption of either plane stress or plane strain. The calculated stress-intensity factors from the present analysis were compared with those from the literature whenever possible and were generally found to be in good agreement. The stress-intensity factors at the midplane for all specimens analyzed were within 3 percent of the two dimensional plane strain values. The stress intensity factors at the specimen surfaces were considerably lower than at the midplanes. For the center-crack tension specimens with large thickness to crack-length ratios, the stress-intensity factor reached a maximum near the surface of the specimen. In all other specimens considered the maximum stress intensity occurred at the midplane.

The near-infrared properties of compact binary systems

NASA Astrophysics Data System (ADS)

Froning, Cynthia Suzanne

I present H- and K-band light curves of the dwarf nova cataclysmic variable (CV), IP Peg, and the novalike CV, RW Tri, and an H-band light curve of the novalike CV, SW Sex. All three systems showed contributions from the late-type secondary star and the accretion disk, including a primary eclipse of the accretion disk by the secondary star and a secondary eclipse of the star by the disk. The ellipsoidal variations of the secondary star in IP Peg were modeled and subtracted from the data. The subtracted light curves show a pronounced double-hump variation, resembling those seen in the dwarf novae WZ Sge and AL Com. The primary eclipse was modeled using maximum entropy disk mapping techniques. The accretion disk has a flat intensity distribution and a low brightness temperature (Tbr ~= 3000-4000 K). Superimposed on the face of the disk is the bright spot, where the mass accretion stream impacts the disk; the position of the bright spot is different from the range of positions seen at visible wavelengths. The near-infrared accretion disk flux is dominated by optically thin emission. The eclipse depth is too shallow to be caused by a fully opaque accretion disk. The NIR light curves in RW Tri show a deep primary eclipse of the accretion disk, ellipsoidal variations from the secondary star, a secondary eclipse, and strong flickering in the disk flux. The depth of the secondary eclipse indicates that the accretion disk is opaque. The light curve also has a hump extending from φ = 0.1-0.9 which was successfully modeled as flux from the inner face of the secondary star when heated by a ~0.2 L Lsolar source. The radial brightness temperature profile of the outer disk is consistent with models of a disk in steady-state for a mass transfer rate of M~=5×10- 10 Msolaryr- 1 . At small disk radii, however, the brightness temperature profile is flatter than the steady-state model. The H-band light curve of SW Sex is dominated by emission from the accretion disk. As in RW Tri, the light curve has a hump outside of primary eclipse which was modeled as flux from the secondary star when irradiated by a 0.2-0.3 Lsolar source. The light curve has a dip at φ = 0.5 which is consistent with an eclipse of the irradiated face of the secondary star by an opaque accretion disk. The accretion disk has a brightness temperature profile much flatter than the theoretical profile of a steady- state disk. The disk is asymmetric, with the front of the disk (the side facing the secondary star at mid-eclipse) hotter than the back. The bright spot, which appears in visible disk maps of SW Sex, is not seen in the NIR light curve. I also present H-band light curves of the X-ray binary system, A0620-00, and NIR spectra of two X-ray binaries, CI Cam, and the relativistic jet source, SS 433. (Abstract shortened by UMI.)

Long-term Bond Strength between Layering Indirect Composite Material and Zirconia Coated with Silicabased Ceramics.

PubMed

Fushiki, Ryosuke; Komine, Futoshi; Honda, Junichi; Kamio, Shingo; Blatz, Markus B; Matsumura, Hideo

2015-06-01

This study evaluated the long-term shear bond strength between an indirect composite material and a zirconia framework coated with silica-based ceramics, taking the effect of different primers into account. A total of 165 airborne-particle abraded zirconia disks were subjected to one of three pretreatments: no pretreatment (ZR-AB), airborne-particle abrasion of zirconia coated with feldspathic porcelain (ZR-PO-AB), and 9.5% hydrofluoric acid etching of zirconia coated with feldspathic porcelain (ZR-PO-HF). An indirect composite material (Estenia C&B) was then bonded to the zirconia disks after they were treated with one of the following primers: Clearfil Photo Bond (CPB), Clearfil Photo Bond with Clearfil Porcelain Bond Activator (CPB + Activator), Estenia Opaque Primer (EOP), Porcelain Liner M Liquid B (PLB), or no priming (CON, control group). Shear bond strength was tested after 100,000 thermocycles, and the data were analyzed using the Steel-Dwass U-test (α = 0.05). For ZR-PO-AB and ZR-PO-HF specimens, bond strength was highest in the CPB+Activator group (25.8 MPa and 22.4 MPa, respectively). Bond strengths were significantly lower for ZR-AB specimens in the CON and PLB groups and for ZR-PO-AB specimens in the CON, CPB, and EOP groups. Combined application of a hydrophobic phosphate monomer (MDP) and silane coupling agent enhanced the long-term bond strength of indirect composite material to a zirconia coated with silica-based ceramics.

The effect of enamel porcelain thickness on color and the ability of a shade guide to prescribe chroma.

PubMed

Jarad, F D; Moss, B W; Youngson, C C; Russell, M D

2007-04-01

To test the null hypothesis that there is no color change when enamel porcelain thickness is changed and to evaluate the ability of a shade guide to prescribe chroma. Three shades (3M1, 3M2 and 3M3) were selected from a Vitapan 3D master shade guide. Five disk specimens were prepared for each shade, consisting of three layers (opacious dentin, dentin and enamel) at thicknesses of 0.6, 0.8 and 0.6mm, respectively. The color of each disk was measured using a spectrophotometer. Enamel porcelain was reduced in thickness to 0.3mm and porcelain disks were remeasured. Reducing the enamel thickness of porcelain disk specimens significantly increased L) (p<0.05), b*, metric chroma and hue angle (p<0.001). For the three shades studied (3M1, 3M2 and 3M3) L* values were not significantly different (p>0.05) and chroma increased for 3M1 with the lowest chroma to 3M3 with the highest chroma, which is in line with the shade guide specifications. Although statistically significant (p<0.001) changes in hue angle between the three shades were small (less than 3 degrees overall). The difference in chroma between the three shades 3M1, 3M2 and 3M3 was greatest for the thin enamel layer than the thick enamel layer. A change in enamel thickness from 0.6 to 0.3mm resulted in a three-unit change in L* and metric chroma and a 4 degrees change in hue angle. A change in enamel porcelain thickness will have a greater effect on higher chromatic shades than those with lower chroma. The ability of the shade guide to prescribe chroma was demonstrated but this could be offset by an anomalous enamel thickness.

Chemistry of a newly detected circumbinary disk in Ophiuchus

NASA Astrophysics Data System (ADS)

Artur de la Villarmois, Elizabeth; Kristensen, Lars E.; Jørgensen, Jes K.; Bergin, Edwin A.; Brinch, Christian; Frimann, Søren; Harsono, Daniel; Sakai, Nami; Yamamoto, Satoshi

2018-06-01

Context. Astronomers recently started discovering exoplanets around binary systems. Therefore, understanding the formation and evolution of circumbinary disks and their environment is crucial for a complete scenario of planet formation. Aims: The purpose of this paper is to present the detection of a circumbinary disk around the system Oph-IRS67 and analyse its chemical and physical structure. Methods: We present high-angular-resolution (0.''4, 60 AU) observations of C17O, H13CO+, C34S, SO2, C2H and c-C3H2 molecular transitions with the Atacama Large Millimeter/submillimeter Array (ALMA) at wavelengths of 0.8 mm. The spectrally and spatially resolved maps reveal the kinematics of the circumbinary disk as well as its chemistry. Molecular abundances are estimated using the non-local thermodynamic equilibrium (LTE) radiative-transfer tool RADEX. Results: The continuum emission agrees with the position of Oph-IRS67 A and B, and reveals the presence of a circumbinary disk around the two sources. The circumbinary disk has a diameter of 620 AU and is well traced by C17O and H13CO+ emission. Two further molecular species, C2H and c-C3H2, trace a higher-density region which is spatially offset from the sources ( 430 AU). Finally, SO2 shows compact and broad emission around only one of the sources, Oph-IRS67 B. The molecular transitions which trace the circumbinary disk are consistent with a Keplerian profile on smaller disk scales (≲200 AU) and an infalling profile for larger envelope scales (≳200 AU). The Keplerian fit leads to an enclosed mass of 2.2 M⊙. Inferred CO abundances with respect to H2 are comparable to the canonical ISM value of 2.7 × 10-4, reflecting that freeze-out of CO in the disk midplane is not significant. Conclusions: Molecular emission and kinematic studies prove the existence and first detection of the circumbinary disk associated with the system Oph-IRS67. The high-density region shows a different chemistry than the disk, being enriched in carbon chain molecules. The lack of methanol emission agrees with the scenario where the extended disk dominates the mass budget in the innermost regions of the protostellar envelope, generating a flat density profile where less material is exposed to high temperatures, and thus, complex organic molecules would be associated with lower column densities. Finally, Oph-IRS67 is a promising candidate for proper motion studies and the detection of both circumstellar disks with higher-angular-resolution observations.

A compact Dopplergraph/magnetograph suitable for space-based measurements of solar oscillations and magnetic fields

NASA Technical Reports Server (NTRS)

Rhodes, E. J., Jr.; Cacciani, A.; Tomczyk, S.; Ulrich, R. K.; Blamont, J.; Howard, R. F.; Dumont, P.; Smith, E. J.

1984-01-01

A compact Dopplergraph/magnetograph placed in a continuous solar-viewing orbit will allow us to make major advancements in our understanding of solar internal structure and dynamics. An international program is currently being conducted at JPL and Mt. Wilson to develop such an instrument. By combining a unique magneto-optical resonance filter with CID and CCD cameras we have been able to obtain full- and partial-disk Dopplergrams and magnetograms. Time series of the velocity images are converted into k-omega power spectra which show clear- the solar nonradial p-mode oscilations. Magnetograms suitable for studying the long-term evolution of solar active regions have also been obtained with this instrument. A flight instrument based on this concept is being studied for possible inclusion in the SOHO mission.

On the nature of the symbiotic star BF Cygni

NASA Technical Reports Server (NTRS)

Mikolajewska, J.; Mikolajewski, M.; Kenyon, S. J.

1989-01-01

Optical and ultraviolet spectroscopy of the symbiotic binary BF Cyg obtained during 1979-1988 is discussed. This system consists of a low-mass M5 giant filling about 50 percent of its tidal volume and a hot, luminous compact object similar to the central star of a planetary nebula. The binary is embedded in an asymmetric nebula which includes a small, high-density region and an extended region of lower density. The larger nebula is formed by a slow wind ejected by the cool component and ionized by the hot star, while the more compact nebula is material expelled by the hot component in the form of a bipolar wind. The analysis indicates that disk accretion is essential to maintain the nuclear burning shell of the hot star.

Accretion disk dynamics in X-ray binaries

NASA Astrophysics Data System (ADS)

Peris, Charith Srian

Accreting X-ray binaries consist of a normal star which orbits a compact object with the former transferring matter onto the later via an accretion disk. These accretion disks emit radiation across the entire electromagnetic spectrum. This thesis exploits two regions of the spectrum, exploring the (1) inner disk regions of an accreting black hole binary, GRS1915+105, using X-ray spectral analysis and (2) the outer accretion disks of a set of neutron star and black hole binaries using Doppler Tomography applied on optical observations. X-ray spectral analysis of black hole binary GRS1915+105: GRS1915+105 stands out as an exceptional black hole primarily due to the wild variability exhibited by about half of its X-ray observations. This study focused on the steady X-ray observations of the source, which were found to exhibit significant curvature in the harder coronal component within the RXTE/PCA band-pass. The roughly constant inner-disk radius seen in a majority of the steady-soft observations is strongly reminiscent of canonical soft state black-hole binaries. Remarkably, the steady-hard observations show the presence of growing truncation in the inner-disk. A majority of the steady observations of GRS1915+105 map to the states observed in canonical black hole binaries which suggests that within the complexity of this source is a simpler underlying basis of states. Optical tomography of X-ray binary systems: Doppler tomography was applied to the strong line features present in the optical spectra of X-ray binaries in order to determine the geometric structure of the systems' emitting regions. The point where the accretion stream hits the disk, also referred to as the "hotspot'', is clearly identified in the neutron star system V691 CrA and the black hole system Nova Muscae 1991. Evidence for stream-disk overflows exist in both systems, consistent with relatively high accretion rates. In contrast, V926 Sco does not show evidence for the presence of a hotspot which is consistent with its lower accretion state. The donor stars in V691 CrA and Nova Muscae 1991 were also detected.

[Microwave sintering of nanometer powder of alumina and zirconia-based dental ceramics].

PubMed

Chen, Yi-Fan; Lu, Dong-Mei; Wan, Qian-Bing; Jin, Yong; Zhu, Ju-Mu

2006-02-01

The objective of the present study was to investigate the feasibility and reliability of sintering alumina and zirconia-based all-ceramic materials through a recently introduced microwave heating technique. The variation of crystal phases, the growth of grain sizes and microstructural features of these materials were evaluated after sintering. Four different groups of powder (l00%Al2O3, 60%Al2O3+40%ZrO2, 40% Al2O3+60%ZrO2, 100% ZrO2) were respectively press-compacted to fabricate green disk samples, 5 specimen of each group were prepared. All the samples were surrounded by refractory materials for heat containment and processed at 1 600 degrees C in a domestic microwave oven (850 W, 2 450 MHz), 1 600 degrees C/5 min for heating rate, 10 min for holding time. After sintering, the phase composition and average grain size of these ceramics were examined using X-ray diffraction (XRD). Their microstructure characteristics were studied by scanning electron microscopy (SEM). All the specimens were successfully sintered with the application of microwave heating system in combination with a suitable thermal insulator. No phase change was found in alumina while monoclinic-zirconia was found to be transformed to tetragonal-zirconia. A little grain size growth of Al2O3 and ZrO2 has been observed with Al2O3 24.1 nm/before and 51.8 nm/after; ZrO2 25.3 nm/before and 29.7 nm/after. The SEM photos indicated that the microwave-sintered Al2O3-ZrO2 ceramics had a uniform crystal distribution and their crystal sizes could be maintained within the range of nanometers. It is expected that in the near future microwave heating system could be a promising substitute for conventional processing methods due to its unparalled advantages, including more rapid heating rate, shortened sintering time, superfine grain size, improved microstructure and much less expensive equipment.

Imaging a Central Ionized Component, a Narrow Ring, and the CO Snowline in the Multigapped Disk of HD 169142

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

Macías, Enrique; Anglada, Guillem; Osorio, Mayra

2017-04-01

We report Very Large Array observations at 7 mm, 9 mm, and 3 cm toward the pre-transitional disk of the Herbig Ae star HD 169142. These observations have allowed us to study the millimeter emission of this disk with the highest angular resolution so far (0.″12 × 0.″09, or 14 au × 11 au, at 7 mm). Our 7 and 9 mm images show a narrow ring of emission at a radius of ∼25 au tracing the outer edge of the inner gap. This ring presents an asymmetric morphology that could be produced by dynamical interactions between the disk andmore » forming planets. Additionally, the azimuthally averaged radial intensity profiles of the 7 and 9 mm images confirm the presence of the previously reported gap at ∼45 au and reveal a new gap at ∼85 au. We analyzed archival DCO{sup +}(3–2) and C{sup 18}O(2–1) ALMA observations, showing that the CO snowline is located very close to this third outer gap. This suggests that growth and accumulation of large dust grains close to the CO snowline could be the mechanism responsible for this proposed outer gap. Finally, a compact source of emission is detected at 7 mm, 9 mm, and 3 cm toward the center of the disk. Its flux density and spectral index indicate that it is dominated by free–free emission from ionized gas, which could be associated with the photoionization of the inner disk, an independent object, or an ionized jet.« less

Disk-driven hydromagnetic winds as a key ingredient of active galactic nuclei unification schemes

NASA Technical Reports Server (NTRS)

Konigl, Arieh; Kartje, John F.

1994-01-01

Centrifugally driven winds from the surfaces of magnetized accretion disks have been recognized as an attractive mechanism of removing the angular momentum of the accreted matter and of producing the bipolar outflows and jets that are often associated with compact astronomical objects. As previously suggested in the context of young stellar objects, such winds have unique observational manifestations stemming from their highly stratified density and velocity structure and from their exposure to the strong continuum radiation field of the compact object. We have applied this scenario to active galactic nuclei (AGNs) and investigated the properties of hydromagnetic outflows that originate within approximately 10(M(sub 8)) pc of the central 10(exp 8)(M(sub 8)) solar mass black hole. On the basis of our results, we propose that hydromagnetic disk-driven winds may underlie the classification of broad-line and narrow-line AGNs (e.g., the Seyfert 1/Seyfert 2 dichotomy) as well as the apparent dearth of luminous Seyfert 2 galaxies. More generally, we demonstrate that such winds could strongly influence the spectral characteristics of Seyfert galaxies, QSOs, and BL Lac objects (BLOs). In our picture, the torus is identified with the outer regions of the wind where dust uplifted from the disk surfaces by gas-grain collisions is embedded in the outflow. Using an efficient radiative transfer code, we show that the infrared emission of Seyfert galaxies and QSOs can be attributed to the reprocessing of the UV/soft X-ray AGN continuum by the dust in the wind and the disk. We demonstrate that the radiation pressure force flattens the dust distribution in objects with comparatively high (but possibly sub-Eddington) bolometric luminosities, and we propose this as one likely reason for the apparent paucity of narrow-line objects among certain high-luminosity AGNs. Using the XSTAR photoionization code, we show that the inner regions of the wind could naturally account for the warm (greater than or approximately equal to 10(exp 5) K) and hot (greater than or approximately equal to 10(exp 6) K) gas components that have been inferred to exist on scales less than or approximately equal to 10(exp 2) pc in several Seyfert galaxies. We suggest that the partially ionized gas in the inner regions of the wind, rather than the dusty, neutral outflow that originates further out in the disk, could account for the bulk of the X-ray absorption in Seyferts observed at relatively small angles to their symmetry axes. Finally, we discuss the application of this model to the interpretation of the approximately 0.6 keV X-ray absorption feature reported in several BLOs.

Interfacial strength development in thermoplastic resins and fiber-reinforced thermoplastic composites

NASA Technical Reports Server (NTRS)

Howes, Jeremy C.; Loos, Alfred C.

1987-01-01

An experimental program to develop test methods to be used to characterize interfacial (autohesive) strength development in polysulfone thermoplastic resin and graphite-polysulfone prepreg during processing is reported. Two test methods were used to examine interfacial strength development in neat resin samples. These included an interfacial tension test and a compact tension (CT) fracture toughness test. The interfacial tensile test proved to be very difficult to perform with a considerable amount of data scatter. Thus, the interfacial test was discarded in favor of the fracture toughness test. Interfacial strength development was observed by measuring the refracture toughness of precracked compact tension specimens that were rehealed at a given temperature and contact time. The measured refracture toughness was correlated with temperature and contact time. Interfacial strength development in graphite-polysulfone unidirectional composites was measured using a double cantilever beam (DCB) interlaminar fracture toughness test. The critical strain energy release rate of refractured composite specimens was measured as a function of healing temperature and contact time.

Subcritical crack growth in soda-lime glass in combined mode I and mode II loading

NASA Technical Reports Server (NTRS)

Singh, Dileep; Shetty, Dinesh K.

1990-01-01

Subcritical crack growth under mixed-mode loading was studied in soda-lime glass. Pure mode I, combined mode I and mode II, and pure mode II loadings were achieved in precracked disk specimens by loading in diametral compression at selected angles with respect to the symmetric radial crack. Crack growth was monitored by measuring the resistance changes in a microcircuit grid consisting of parallel, electrically conducting grid lines deposited on the surface of the disk specimens by photolithography. Subcritical crack growth rates in pure mode I, pure mode II, and combined mode I and mode II loading could be described by an exponential relationship between crack growth rate and an effective crack driving force derived from a mode I-mode II fracture toughness envelope. The effective crack driving force was based on an empirical representation of the noncoplanar strain energy release rate. Stress intensities for kinked cracks were assessed using the method of caustics and an initial decrease and a subsequent increase in the subcritical crack growth rates of kinked cracks were shown to correlate with the variations of the mode I and the mode II stress intensities.

[Comparison of surface roughness of nanofilled and microhybrid composite resins after curing and polishing].

PubMed

Jiang, Hong; Lv, Da; Liu, Kailei; Zhang, Weisheng; Yao, Yao; Liao, Chuhong

2014-05-01

To compare the surface roughness of nanofilled dental composite resin and microhybrid composite resins after curing and polishing. A nanofilled composite (Z350) and 4 microhybrid composites (P60, Z250, Spectrum, and AP-X) were fabricated from the lateral to the medial layers to prepare 8 mm×8 mm×5 mm cubical specimens. The 4 lateral surfaces of each specimens were polished with abrasive disks (Super-Snap). Profilometer was used to test the mean surface roughness (Ra) after polishing. P60 had the lowest Ra (0.125∓0.030 µm) followed by Z250 and Spectrum. The Ra of Z350 (0.205∓0.052 µm) was greater than that of the other 3 resins, and AP-X had the roughest surfaces. Under scanning electron microscope, the polished faces of P60 resin were characterized by minor, evenly distributed particles with fewer scratches; the polished faces of Z350 presented with scratches where defects of the filling material could be seen. The nanofilled composite Z350 has smooth surface after polishing by abrasive disks, but its smoothness remains inferior to that of other micro-hybrid composite resins.

Shear punch and ball microhardness measurements of 14 MeV neutron irradiation hardening in five metals

NASA Astrophysics Data System (ADS)

Shinohara, K.; Lucas, G. E.; Odette, G. R.

1985-08-01

The irradiation hardening response of five metals irradiated in RTNS-II was investigated using a combination of ball microhardness and shear punch test techniques. The specimens were transmission electron microscopy disks of pure nickel, Ni-5wt%Si, pure iron, solution annealed prime candidate alloy (PCA) for Path A, and 40% cold worked MFE 316 stainless steel. Specimens were irradiated in RTNS-II to fluences in the range 6 × 10 16 to 6 × 10 17 n/cm 2. Only limited ball microhardness data could be obtained because of disk thickness. However, the ball microhardness data obtained were in good agreement with shear punch data. It was found that the pure metals exhibited little hardening after exposure to fluences of ~1 × 10 17 n/cm 2, but Ni-5 Si exhibited significant hardening after 6 × 10 17 n/cm 2. Hardening in PCA was similar to that observed in solution annealed 316 stainless steel; and hardening in 40% cold worked MFE 316 was relatively small after 6 × 10 17 n/cm 2. The Ni-5 Si response may be due to irradiation induced precipitation.

Fissure sealant materials: Wear resistance of flowable composite resins.

PubMed

Asefi, Sohrab; Eskandarion, Solmaz; Hamidiaval, Shadi

2016-01-01

Background. Wear resistance of pit and fissure sealant materials can influence their retention. Wear characteristics of sealant materials may determine scheduling of check-up visits. The aim of this study was to compare wear resistance of two flowable composite resins with that of posterior composite resin materials. Methods. Thirty-five disk-shaped specimens were prepared in 5 groups, including two flowable composite resins (Estelite Flow Quick and Estelite Flow Quick High Flow), Filtek P90 and Filtek P60 and Tetric N-Ceram. The disk-shaped samples were prepared in 25-mm diameter by packing them into a two-piece aluminum mold and then light-cured. All the specimens were polished for 1minute using 600-grit sand paper. The samples were stored in distilled water at room temperature for 1 week and then worn by two-body abrasion test using "pin-on-disk" method (with distilled water under a 15-Nload at 0.05 m/s, for a distance of 100 meter with Steatite ceramic balls antagonists). A Profilometer was used for evaluating the surface wear. Data were analyzed with the one-way ANOVA. Results. Estelite Flow Quick exhibited 2708.9 ± 578.1 μm(2) and Estelite Flow Quick High Flow exhibited 3206 ± 2445.1 μm(2)of wear but there were no significant differences between the groups. They demonstrated similar wear properties. Conclusion. Estelite flowable composite resins have wear resistance similar to nano- and micro-filled and micro-hybrid composite resins. Therefore, they can be recommended as pit and fissure sealant materials in the posterior region with appropriate mechanical characteristics.

Fissure sealant materials: Wear resistance of flowable composite resins

PubMed Central

Asefi, Sohrab; Eskandarion, Solmaz; Hamidiaval, Shadi

2016-01-01

Background. Wear resistance of pit and fissure sealant materials can influence their retention. Wear characteristics of sealant materials may determine scheduling of check-up visits. The aim of this study was to compare wear resistance of two flowable composite resins with that of posterior composite resin materials. Methods. Thirty-five disk-shaped specimens were prepared in 5 groups, including two flowable composite resins (Estelite Flow Quick and Estelite Flow Quick High Flow), Filtek P90 and Filtek P60 and Tetric N-Ceram. The disk-shaped samples were prepared in 25-mm diameter by packing them into a two-piece aluminum mold and then light-cured. All the specimens were polished for 1minute using 600-grit sand paper. The samples were stored in distilled water at room temperature for 1 week and then worn by two-body abrasion test using "pin-on-disk" method (with distilled water under a 15-Nload at 0.05 m/s, for a distance of 100 meter with Steatite ceramic balls antagonists). A Profilometer was used for evaluating the surface wear. Data were analyzed with the one-way ANOVA. Results. Estelite Flow Quick exhibited 2708.9 ± 578.1 μm2 and Estelite Flow Quick High Flow exhibited 3206 ± 2445.1 μm2of wear but there were no significant differences between the groups. They demonstrated similar wear properties. Conclusion. Estelite flowable composite resins have wear resistance similar to nano- and micro-filled and micro-hybrid composite resins. Therefore, they can be recommended as pit and fissure sealant materials in the posterior region with appropriate mechanical characteristics. PMID:27651887

Effect of silica coating on fracture strength of glass-infiltrated alumina ceramic cemented to dentin.

PubMed

Xie, Haifeng; Zhu, Ye; Chen, Chen; Gu, Ning; Zhang, Feimin

2011-10-01

To examine the availability of sol-gel processed silica coating for alumina-based ceramic bonding, and determine which silica sol concentration was appropriate for silica coating. Sixty disks of In-Ceram alumina ceramic were fabricated and randomly divided into 5 main groups. The disks received 5 different surface conditioning treatments: Group Al, sandblasted; Group AlC, sandblasted + silane coupling agent applied; Groups Al20C, Al30C, and Al40C, sandblasted, silica coating via sol-gel process prepared using 20 wt%, 30 wt%, and 40 wt% silica sols, and then silane coupling agent applied. Before bonding, one-step adhesives were applied on pre-prepared ceramic surfaces of all groups. Then, 60 dentin specimens were prepared and conditioned with phosphoric acid and one-step adhesive. Ceramic disks of all groups were cemented to dentin specimens with dual-curing resin cements. Fracture strength was determined at 24 h and after 20 days of storage in water. Groups Al20C, Al30C, and Al40C revealed significantly higher fracture strength than groups Al and AlC. No statistically significant difference in fracture strength was found between groups Al and AlC, or among groups Al20C, Al30C, and Al40C. Fracture strength values of all the groups did not change after 20 days of water storage. Sol-gel processed silica coating can enhance fracture strength of In-Ceram alumina ceramic after bonding to dentin, and different silica sol concentrations produced the same effects. Twenty days of water storage did not decrease the fracture strength.

Longterm lightcurves of X-ray binaries

NASA Astrophysics Data System (ADS)

Clarkson, William

The X-ray Binaries (XRB) consist of a compact object and a stellar companion, which undergoes large-scale mass-loss to the compact object by virtue of the tight ( P orb usually hours-days) orbit, producing an accretion disk surrounding the compact object. The liberation of gravitational potential energy powers exotic high-energy phenomena, indeed the resulting accretion/ outflow process is among the most efficient energy-conversion machines in the universe. The Burst And Transient Source Experiment (BATSE) and RXTE All Sky Monitor (ASM) have provided remarkable X-ray lightcurves above 1.3keV for the entire sky, at near-continuous coverage, for intervals of 9 and 7 years respectively (with ~3 years' overlap). With an order of magnitude increase in sensitivity compared to previous survey instruments, these instruments have provided new insight into the high-energy behaviour of XRBs on timescales of tens to thousands of binary orbits. This thesis describes detailed examination of the long-term X-ray lightcurves of the neutron star XRB X2127+119, SMC X-1, Her X- 1, LMC X-4, Cyg X-2 and the as yet unclassified Circinus X-1, and for Cir X-1, complementary observations in the IR band. Chapters 1 & 2 introduce X-ray Binaries in general and longterm periodicities in particular. Chapter 3 introduces the longterm datasets around which this work is based, and the chosen methods of analysis of these datasets. Chapter 4 examines the burst history of the XRB X2127+119, suggesting three possible interpretations of the apparently contradictory X-ray emission from this system, including a possible confusion of two spatially distinct sources (which was later vindicated by high-resolution imaging). Chapters 5 and 6 describe the characterisation of accretion disk warping, providing observational verification of the prevailing theoretical framework for such disk-warps. Chapters 7 & 8 examine the enigmatic XRB Circinus X-1 with high-resolution IR spectroscopy (chapter 7) and the RXTE/ASM (chapter 8), establishing an improved orbital ephemeris and suggesting the system may be in a state of rapid post- supernova evolution. In chapter 8 we follow this up with a direct search for the X-ray supernova remnant expected from such a system, concluding that with present observations the diffuse emission from Cir X-1 is indistinguishable from scattering by dust-grains in the interstellar medium.

Data development for ASTM E24.06.02 round robin program on instability prediction

NASA Technical Reports Server (NTRS)

Mccabe, D. E.

1979-01-01

Basis data for use in an ASTM E24.06.02 task group round robin activity was developed. Compact specimens were made of 2024-T351, 7075-T651 aluminum alloys, and 304 stainless steel. All were 12.7 mm thick and planar dimension variables incorporated were for 1T, 2T and 4T sizes. Representative raw data for each material and specimen size are contained herein. R-curves plotted in terms of delta a physical and delta a effective are plotted for each material.

Bone histology in extant and fossil penguins (Aves: Sphenisciformes).

PubMed

Ksepka, Daniel T; Werning, Sarah; Sclafani, Michelle; Boles, Zachary M

2015-11-01

Substantial changes in bone histology accompany the secondary adaptation to life in the water. This transition is well documented in several lineages of mammals and non-avian reptiles, but has received relatively little attention in birds. This study presents new observations on the long bone microstructure of penguins, based on histological sections from two extant taxa (Spheniscus and Aptenodytes) and eight fossil specimens belonging to stem lineages (†Palaeospheniscus and several indeterminate Eocene taxa). High bone density in penguins results from compaction of the internal cortical tissues, and thus penguin bones are best considered osteosclerotic rather than pachyostotic. Although the oldest specimens sampled in this study represent stages of penguin evolution that occurred at least 25 million years after the loss of flight, major differences in humeral structure were observed between these Eocene stem taxa and extant taxa. This indicates that the modification of flipper bone microstructure continued long after the initial loss of flight in penguins. It is proposed that two key transitions occurred during the shift from the typical hollow avian humerus to the dense osteosclerotic humerus in penguins. First, a reduction of the medullary cavity occurred due to a decrease in the amount of perimedullary osteoclastic activity. Second, a more solid cortex was achieved by compaction. In extant penguins and †Palaeospheniscus, most of the inner cortex is formed by rapid osteogenesis, resulting an initial latticework of woven-fibered bone. Subsequently, open spaces are filled by slower, centripetal deposition of parallel-fibered bone. Eocene stem penguins formed the initial latticework, but the subsequent round of compaction was less complete, and thus open spaces remained in the adult bone. In contrast to the humerus, hindlimb bones from Eocene stem penguins had smaller medullary cavities and thus higher compactness values compared with extant taxa. Although cortical lines of arrested growth have been observed in extant penguins, none was observed in any of the current sampled specimens. Therefore, it is likely that even these 'giant' penguin taxa completed their growth cycle without a major pause in bone deposition, implying that they did not undergo a prolonged fasting interval before reaching adult size. © 2015 Anatomical Society.

Bone histology in extant and fossil penguins (Aves: Sphenisciformes)

PubMed Central

Ksepka, Daniel T; Werning, Sarah; Sclafani, Michelle; Boles, Zachary M

2015-01-01

Substantial changes in bone histology accompany the secondary adaptation to life in the water. This transition is well documented in several lineages of mammals and non-avian reptiles, but has received relatively little attention in birds. This study presents new observations on the long bone microstructure of penguins, based on histological sections from two extant taxa (Spheniscus and Aptenodytes) and eight fossil specimens belonging to stem lineages (†Palaeospheniscus and several indeterminate Eocene taxa). High bone density in penguins results from compaction of the internal cortical tissues, and thus penguin bones are best considered osteosclerotic rather than pachyostotic. Although the oldest specimens sampled in this study represent stages of penguin evolution that occurred at least 25 million years after the loss of flight, major differences in humeral structure were observed between these Eocene stem taxa and extant taxa. This indicates that the modification of flipper bone microstructure continued long after the initial loss of flight in penguins. It is proposed that two key transitions occurred during the shift from the typical hollow avian humerus to the dense osteosclerotic humerus in penguins. First, a reduction of the medullary cavity occurred due to a decrease in the amount of perimedullary osteoclastic activity. Second, a more solid cortex was achieved by compaction. In extant penguins and †Palaeospheniscus, most of the inner cortex is formed by rapid osteogenesis, resulting an initial latticework of woven-fibered bone. Subsequently, open spaces are filled by slower, centripetal deposition of parallel-fibered bone. Eocene stem penguins formed the initial latticework, but the subsequent round of compaction was less complete, and thus open spaces remained in the adult bone. In contrast to the humerus, hindlimb bones from Eocene stem penguins had smaller medullary cavities and thus higher compactness values compared with extant taxa. Although cortical lines of arrested growth have been observed in extant penguins, none was observed in any of the current sampled specimens. Therefore, it is likely that even these ‘giant’ penguin taxa completed their growth cycle without a major pause in bone deposition, implying that they did not undergo a prolonged fasting interval before reaching adult size. PMID:26360700

Compact, Portable Pulsed-Power

DTIC Science & Technology

2006-08-31

adding this fast pulse to a slow, 30kV pulse which is below the threshold for significant corona emission. This scheme is presently being explored with...the smaller stressed electrode area. Further results from these systems were reported at the 2006 Power Modulator Conference in Washington, D.C...BLT and the medium-BLT is similar. The mini BLT electrodes are made of 3 mm thick molybdenum disks with a 3 mm central hole, capped on a hollow OFHC 1

Effect of guided relaxation and imagery on falls self-efficacy: a randomized controlled trial.

PubMed

Kim, Bang Hyun; Newton, Roberta A; Sachs, Michael L; Glutting, Joseph J; Glanz, Karen

2012-06-01

To examine the effects of guided relaxation and imagery (GRI) on improvement in falls self-efficacy in older adults who report having a fear of falling. Randomized, controlled trial with allocation to GRI or guided relaxation with music of choice. General community. Ninety-one men and women aged 60 to 92. Participants were randomized to listen to a GRI audio compact disk (intervention group) or a guided relaxation audio compact disk and music of choice (control group) twice a week for 6 weeks for 10 minutes per session. Primary outcome measure was the Short Falls Efficacy Scale-International (FES-I). Secondary outcome measures were the Leisure Time Exercise Questionnaire (LTEQ) and the Timed Up and Go (TUG) mobility test. GRI participants reported greater improvements on the Short FES-I (P = .002) and LTEQ (P = .001) scores and shorter time on the TUG (P = .002) than the guided relaxation and music-of-choice group. GRI was more effective at increasing falls self-efficacy and self-reported leisure time exercise and reducing times on a simple mobility test than was guided relaxation with music of choice. GRI is an effective, simple, low-cost tool for older adults to improve falls self-efficacy and leisure time exercise behaviors. © 2012, Copyright the Authors Journal compilation © 2012, The American Geriatrics Society.

Rotational properties of hypermassive neutron stars from binary mergers

NASA Astrophysics Data System (ADS)

Hanauske, Matthias; Takami, Kentaro; Bovard, Luke; Rezzolla, Luciano; Font, José A.; Galeazzi, Filippo; Stöcker, Horst

2017-08-01

Determining the differential-rotation law of compact stellar objects produced in binary neutron stars mergers or core-collapse supernovae is an old problem in relativistic astrophysics. Addressing this problem is important because it impacts directly on the maximum mass these objects can attain and, hence, on the threshold to black-hole formation under realistic conditions. Using the results from a large number of numerical simulations in full general relativity of binary neutron star mergers described with various equations of state and masses, we study the rotational properties of the resulting hypermassive neutron stars. We find that the angular-velocity distribution shows only a modest dependence on the equation of state, thus exhibiting the traits of "quasiuniversality" found in other aspects of compact stars, both isolated and in binary systems. The distributions are characterized by an almost uniformly rotating core and a "disk." Such a configuration is significantly different from the j -constant differential-rotation law that is commonly adopted in equilibrium models of differentially rotating stars. Furthermore, the rest-mass contained in such a disk can be quite large, ranging from ≃0.03 M⊙ in the case of high-mass binaries with stiff equations of state, up to ≃0.2 M⊙ for low-mass binaries with soft equations of state. We comment on the astrophysical implications of our findings and on the long-term evolutionary scenarios that can be conjectured on the basis of our simulations.

Comparison of manual and automated nucleic acid extraction methods from clinical specimens for microbial diagnosis purposes.

PubMed

Wozniak, Aniela; Geoffroy, Enrique; Miranda, Carolina; Castillo, Claudia; Sanhueza, Francia; García, Patricia

2016-11-01

The choice of nucleic acids (NAs) extraction method for molecular diagnosis in microbiology is of major importance because of the low microbial load, different nature of microorganisms, and clinical specimens. The NA yield of different extraction methods has been mostly studied using spiked samples. However, information from real human clinical specimens is scarce. The purpose of this study was to compare the performance of a manual low-cost extraction method (Qiagen kit or salting-out extraction method) with the automated high-cost MagNAPure Compact method. According to cycle threshold values for different pathogens, MagNAPure is as efficient as Qiagen for NA extraction from noncomplex clinical specimens (nasopharyngeal swab, skin swab, plasma, respiratory specimens). In contrast, according to cycle threshold values for RNAseP, MagNAPure method may not be an appropriate method for NA extraction from blood. We believe that MagNAPure versatility reduced risk of cross-contamination and reduced hands-on time compensates its high cost. Copyright © 2016 Elsevier Inc. All rights reserved.

Fracture toughness determination using spiral-grooved cylindrical specimen and pure torsional loading

DOEpatents

Wang, Jy-An; Liu, Kenneth C.

2003-07-08

A method for determining fracture toughness K.sub.IC of materials ranging from metallic alloys, brittle ceramics and their composites, and weldments. A cylindrical specimen having a helical V-groove with a 45.degree. pitch is subjected to pure torsion. This loading configuration creates a uniform tensile-stress crack-opening mode, and a transverse plane-strain state along the helical groove. The full length of the spiral groove is equivalent to the thickness of a conventional compact-type specimen. K.sub.IC values are determined from the fracture torque and crack length measured from the test specimen using a 3-D finite element program (TOR3D-KIC) developed for the purpose. In addition, a mixed mode (combined tensile and shear stress mode) fracture toughness value can be determined by varying the pitch of the helical groove. Since the key information needed for determining the K.sub.IC value is condensed in the vicinity of the crack tip, the specimen can be significantly miniaturized without the loss of generality.

The INTEGRAL long monitoring of persistent ultra compact X-ray bursters

NASA Astrophysics Data System (ADS)

Fiocchi, M.; Bazzano, A.; Ubertini, P.; Bird, A. J.; Natalucci, L.; Sguera, V.

2008-12-01

Context: The combination of compact objects, short period variability and peculiar chemical composition of the ultra compact X-ray binaries make up a very interesting laboratory to study accretion processes and thermonuclear burning on the neutron star surface. Improved large optical telescopes and more sensitive X-ray satellites have increased the number of known ultra compact X-ray binaries allowing their study with unprecedented detail. Aims: We analyze the average properties common to all ultra compact bursters observed by INTEGRAL from 0.2 keV to 150 keV. Methods: We have performed a systematic analysis of the INTEGRAL public data and Key-Program proprietary observations of a sample of the ultra compact X-ray binaries. In order to study their average properties in a very broad energy band, we combined INTEGRAL with BeppoSAX and SWIFT data whenever possible. For sources not showing any significant flux variations along the INTEGRAL monitoring, we build the average spectrum by combining all available data; in the case of variable fluxes, we use simultaneous INTEGRAL and SWIFT observations when available. Otherwise we compared IBIS and PDS data to check the variability and combine BeppoSAX with INTEGRAL /IBIS data. Results: All spectra are well represented by a two component model consisting of a disk-blackbody and Comptonised emission. The majority of these compact sources spend most of the time in a canonical low/hard state, with a dominating Comptonised component and accretion rate dot {M} lower than 10-9 {M⊙}/yr, not depending on the model used to fit the data. INTEGRAL is an ESA project with instruments and Science Data Center funded by ESA member states (especially the PI countries: Denmark, France, Germany, Italy, Switzerland, Spain), Czech Republic and Poland, and with the participation of Russia and the USA.

Ignition of a Combustible Atmosphere by Incandescent Carbon Wear Particles

NASA Technical Reports Server (NTRS)

Buckley, Donald H.; Swikert, Max A.; Johnson, Robert L.

1960-01-01

A study was made to determine whether carbon wear particles from carbon elements in sliding contact with a metal surface were sufficiently hot to cause ignition of a combustible atmosphere. In some machinery, electric potential differences and currents may appear at the carbon-metal interface. For this reason the effect of these voltages and currents on the ability of carbon wear particles to cause ignition was evaluated. The test specimens used in the investigation were carbon vanes taken from a fuel pump and flat 21-inch-diameter 2 metal disks (440-C stainless steel) representing the pump housing. During each experiment a vane was loaded against a disk with a 0.5-pound force, and the disk was rotated to give a surface speed of 3140 feet per minute. The chamber of the apparatus that housed the vane and the disk was filled with a combustible mixture of air and propane. Various voltages and amperages were applied across the vane-disk interface. Experiments were conducted at temperatures of 75, 350, 400, and 450 F. Fires were produced by incandescent carbon wear particles obtained at conditions of electric potential as low as 106 volts and 0.3 ampere at 400 F. Ignitions were obtained only with carbon wear particles produced with an electric potential across the carbon-vane-disk interface. No ignitions were obtained with carbon wear particles produced in the absence of this potential; also, the potential difference produced no ignitions in the absence of carbon wear particles. A film supplement showing ignition by incandescent wear particles is available.

Electron Microscopy and Analytical X-ray Characterization of Compositional and Nanoscale Structural Changes in Fossil Bone

NASA Astrophysics Data System (ADS)

Boatman, Elizabeth Marie

The nanoscale structure of compact bone contains several features that are direct indicators of bulk tissue mechanical properties. Fossil bone tissues represent unique opportunities to understand the compact bone structure/property relationships from a deep time perspective, offering a possible array of new insights into bone diseases, biomimicry of composite materials, and basic knowledge of bioapatite composition and nanoscale bone structure. To date, most work with fossil bone has employed microscale techniques and has counter-indicated the survival of bioapatite and other nanoscale structural features. The obvious disconnect between the use of microscale techniques and the discernment of nanoscale structure has prompted this work. The goal of this study was to characterize the nanoscale constituents of fossil compact bone by applying a suite of diffraction, microscopy, and spectrometry techniques, representing the highest levels of spatial and energy resolution available today, and capable of complementary structural and compositional characterization from the micro- to the nanoscale. Fossil dinosaur and crocodile long bone specimens, as well as modern ratite and crocodile femurs, were acquired from the UC Museum of Paleontology. Preserved physiological features of significance were documented with scanning electron microscopy back-scattered imaging. Electron microprobe wavelength-dispersive X-ray spectroscopy (WDS) revealed fossil bone compositions enriched in fluorine with a complementary loss of oxygen. X-ray diffraction analyses demonstrated that all specimens were composed of apatite. Transmission electron microscopy (TEM) imaging revealed preserved nanocrystallinity in the fossil bones and electron diffraction studies further identified these nanocrystallites as apatite. Tomographic analyses of nanoscale elements imaged by TEM and small angle X-ray scattering were performed, with the results of each analysis further indicating that nanoscale structure is highly conserved in these four fossil specimens. Finally, the results of this study indicate that bioapatite can be preserved in even the most ancient vertebrate specimens, further supporting the idea that fossilization is a preservational process. This work also underlines the importance of using appropriately selected characterization and analytical techniques for the study of fossil bone, especially from the perspective of spatial resolution and the scale of the bone structural features in question.

Diode pumped solid state kilohertz disk laser system for time-resolved combustion diagnostics under microgravity at the drop tower Bremen

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

Wagner, Volker; Paa, Wolfgang; Triebel, Wolfgang

We describe a specially designed diode pumped solid state laser system based on the disk laser architecture for combustion diagnostics under microgravity (μg) conditions at the drop tower in Bremen. The two-stage oscillator-amplifier-system provides an excellent beam profile (TEM{sub 00}) at narrowband operation (Δλ < 1 pm) and is tunable from 1018 nm to 1052 nm. The laser repetition rate of up to 4 kHz at pulse durations of 10 ns enables the tracking of processes on a millisecond time scale. Depending on the specific issue it is possible to convert the output radiation up to the fourth harmonic aroundmore » 257 nm. The very compact laser system is integrated in a slightly modified drop capsule and withstands decelerations of up to 50 g (>11 ms). At first the concept of the two-stage disk laser is briefly explained, followed by a detailed description of the disk laser adaption to the drop tower requirements with special focus on the intended use under μg conditions. In order to demonstrate the capabilities of the capsule laser as a tool for μg combustion diagnostics, we finally present an investigation of the precursor-reactions before the droplet ignition using 2D imaging of the Laser Induced Fluorescence of formaldehyde.« less

Science packages

NASA Astrophysics Data System (ADS)

1997-01-01

Primary science teachers in Scotland have a new updating method at their disposal with the launch of a package of CDi (Compact Discs Interactive) materials developed by the BBC and the Scottish Office. These were a response to the claim that many primary teachers felt they had been inadequately trained in science and lacked the confidence to teach it properly. Consequently they felt the need for more in-service training to equip them with the personal understanding required. The pack contains five disks and a printed user's guide divided up as follows: disk 1 Investigations; disk 2 Developing understanding; disks 3,4,5 Primary Science staff development videos. It was produced by the Scottish Interactive Technology Centre (Moray House Institute) and is available from BBC Education at £149.99 including VAT. Free Internet distribution of science education materials has also begun as part of the Global Schoolhouse (GSH) scheme. The US National Science Teachers' Association (NSTA) and Microsoft Corporation are making available field-tested comprehensive curriculum material including 'Micro-units' on more than 80 topics in biology, chemistry, earth and space science and physics. The latter are the work of the Scope, Sequence and Coordination of High School Science project, which can be found at http://www.gsh.org/NSTA_SSandC/. More information on NSTA can be obtained from its Web site at http://www.nsta.org.

Constraints on the Neutron Star and Inner Accretion Flow in Serpens X-1 Using Nustar

NASA Technical Reports Server (NTRS)

Miller, J. M.; Parker, M. L.; Fuerst, F.; Bachetti, M.; Barret, D.; Grefenstette, B. W.; Tendulkar, S.; Harrison, F. A.; Boggs, S. E.; Chakrabarty, D.;

CONSTRAINTS ON THE NEUTRON STAR AND INNER ACCRETION FLOW IN SERPENS X-1 USING NuSTAR

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

Miller, J. M.; Parker, M. L.; Fabian, A. C.

2013-12-10

We report on an observation of the neutron star low-mass X-ray binary Serpens X-1, made with NuSTAR. The extraordinary sensitivity afforded by NuSTAR facilitated the detection of a clear, robust, relativistic Fe K emission line from the inner disk. A relativistic profile is required over a single Gaussian line from any charge state of Fe at the 5σ level of confidence, and any two Gaussians of equal width at the same confidence. The Compton back-scattering ''hump'' peaking in the 10-20 keV band is detected for the first time in a neutron star X-ray binary. Fits with relativistically blurred disk reflection modelsmore » suggest that the disk likely extends close to the innermost stable circular orbit (ISCO) or stellar surface. The best-fit blurred reflection models constrain the gravitational redshift from the stellar surface to be z {sub NS} ≥ 0.16. The data are broadly compatible with the disk extending to the ISCO; in that case, z {sub NS} ≥ 0.22 and R {sub NS} ≤ 12.6 km (assuming M {sub NS} = 1.4 M {sub ☉} and a = 0, where a = cJ/GM {sup 2}). If the star is as large or larger than its ISCO, or if the effective reflecting disk leaks across the ISCO to the surface, the redshift constraints become measurements. We discuss our results in the context of efforts to measure fundamental properties of neutron stars, and models for accretion onto compact objects.« less

Reflection Spectra of the Black Hole Binary Candidate MAXI J1535-571 in the Hard State Observed by NuSTAR

NASA Astrophysics Data System (ADS)

Xu, Yanjun; Harrison, Fiona A.; García, Javier A.; Fabian, Andrew C.; Fürst, Felix; Gandhi, Poshak; Grefenstette, Brian W.; Madsen, Kristin K.; Miller, Jon M.; Parker, Michael L.; Tomsick, John A.; Walton, Dominic J.

2018-01-01

We report on a Nuclear Spectroscopic Telescope Array (NuSTAR) observation of the recently discovered bright black hole candidate MAXI J1535-571. NuSTAR observed the source on MJD 58003 (five days after the outburst was reported). The spectrum is characteristic of a black hole binary in the hard state. We observe clear disk reflection features, including a broad Fe Kα line and a Compton hump peaking around 30 keV. Detailed spectral modeling reveals a narrow Fe Kα line complex centered around 6.5 keV on top of the strong relativistically broadened Fe Kα line. The narrow component is consistent with distant reflection from moderately ionized material. The spectral continuum is well described by a combination of cool thermal disk photons and a Comptonized plasma with the electron temperature {{kT}}{{e}}=19.7+/- 0.4 keV. An adequate fit can be achieved for the disk reflection features with a self-consistent relativistic reflection model that assumes a lamp-post geometry for the coronal illuminating source. The spectral fitting measures a black hole spin a> 0.84, inner disk radius {R}{in}< 2.01 {r}{ISCO}, and a lamp-post height h={7.2}-2.0+0.8 {r}{{g}} (statistical errors, 90% confidence), indicating no significant disk truncation and a compact corona. Although the distance and mass of this source are not currently known, this suggests the source was likely in the brighter phases of the hard state during this NuSTAR observation.

Hand-held photomicroscope

NASA Technical Reports Server (NTRS)

Zabower, H. R. (Inventor)

1973-01-01

A small, lightweight, compact, hand-held photomicroscope provides simultaneous viewing and photographing, with adjustable specimen illumination and exchangeable camera format. The novel photomicroscope comprises a main housing having a top plate, bottom plate, and side walls. The objective lens is mounted on the top plate in an inverted manner relative to the normal type of mounting. The specimen holder has an adjusting mechanism for adjustably moving the specimen vertically along an axis extending through the objective lens as well as transverse of the axis. The lens system serves to split the beam of light into two paths, one to the eyepiece and the other to a camera mounting. A light source is mounted on the top plate and directs light onto the specimen. A rheostat device is mounted on the top plate and coupled to the power supply for the light source so that the intensity of the light may be varied.

Calcification of MC3T3-E1 cells on titanium and zirconium.

PubMed

Umezawa, Takayuki; Chen, Peng; Tsutsumi, Yusuke; Doi, Hisashi; Ashida, Maki; Suzuki, Shoichi; Moriyama, Keiji; Hanawa, Takao

2015-01-01

To confirm similarity of hard tissue compatibility between titanium and zirconium, calcification of MC3T3-E1 cells on titanium and zirconium was evaluated in this study. Mirror-polished titanium (Ti) and zirconium (Zr) disks and zirconium-sputter deposited titanium (Zr/Ti) were employed in this study. The surface of specimens were characterized using scanning electron microscopy and X-ray diffraction. Then, the cellular proliferation, differentiation and calcification of MC3T3-E1 cells on specimens were investigated. The surface of Zr/Ti was much smoother and cleaner than those of Ti and Zr. The proliferation of the cell was the same among three specimens, while the differentiation and calcification on Zr/Ti were faster than those on Ti and Zr. Therefore, Ti and Zr showed the identical hard tissue compatibility according to the evaluation with MC3T3-E1 cells. Sputter deposition may improve cytocompatibility.

Guarded Flat Plate Cryogenic Test Apparatus and Calorimeter

NASA Technical Reports Server (NTRS)

Fesmire, James E. (Inventor); Johnson, Wesley L. (Inventor)

2017-01-01

A test apparatus for thermal energy measurement of disk-shaped test specimens has a cold mass assembly locatable within a sealable chamber with a guard vessel having a guard chamber to receive a liquid fluid and a bottom surface to contact a cold side of a test specimen, and a test vessel having a test chamber to receive a liquid fluid and encompassed on one side by a center portion of the bottom surface shared with the guard vessel. A lateral wall assembly of the test vessel is closed by a vessel top, the lateral wall assembly comprising an outer wall and an inner wall having opposing surfaces that define a thermal break including a condensable vapor pocket to inhibit heat transfer through the lateral wall from the guard vessel to the test vessel. A warm boundary temperature surface is in thermal communication with a lower surface of the test specimen.

On the Role of Dimensionless Elastic Fracture Mechanics.

DTIC Science & Technology

1985-07-03

34.’ . . . .- . . - . . . - ... - . .. . . . . . -8-.V 6. B.M. Wundt , "A Unified Interpretation of Room Temperature Strength of Notched...207s (1948). D.H. Winne and B.M. Wundt , Application of the Griffith-Irwin theory of crack propagation to the bursting behavior of disks, including... Wundt , A unified interpretation of room-temperature strength of notched specimens as influenced by their size. Metals Engng. Conf., ASME Paper No

Evaluation of Elber's Crack Closure Model as an Explanation of Train Load Sequence Effects on Crack Growth Rates

DOT National Transportation Integrated Search

1990-06-01

Elber's crack closure model is studied in relation to the results of laboratory spectrum crack growth tests on compact tension specimens (CTS) fabricated from rail effected by mean of an analysis of a center cracked panel (CCP) subjected to an equiva...

Gateway BioBox: A Compact, Multi-Purpose Biological Hardware Suite for In Situ Experiments and Analyses in Deep Space

NASA Astrophysics Data System (ADS)

Smith, D. J.; Parra, M.; Lane, M.; Almeida, E. A.; Space Biosciences Research Branch

2018-02-01

A compilation of NASA's smallest biological hardware systems (plus 1-g gravity controls and ancillary sensors) that will allow for a wide range of specimen cultivation and analysis, from molecular measurements to broader cell and tissue assays.

Effect of surface preparation on the failure load of a highly filled composite bonded to the polymer-monomer matrix of a fiber-reinforced composite.

PubMed

Shimizu, Hiroshi; Tsue, Fumitake; Chen, Zhao-Xun; Takahashi, Yutaka

2009-04-01

The purpose of the present study was to evaluate the effect of surface preparation on the maximum fracture load value of a highly filled composite bonded to the polymer-monomer matrix of a fiber-reinforced composite. A polymer-monomer matrix was made by mixing urethane dimethacrylate and triethyleneglycol dimethacrylate at a ratio of 1:1 with camphorquinone and 2-dimethylaminoethyl methacrylate as a light initiator. The matrix was then polymerized in a disk-shaped silicone mold with a light-polymerizing unit. The flat surfaces of the polymer-monomer matrix disk were prepared in one of the following ways: (1) without preparation; (2) application of silane coupling agent; or (3) application of matrix liquid and prepolymerization. A highly filled composite material was applied and polymerized with a light-polymerizing unit. Additional test specimens made entirely of the polymer-monomer matrix were fabricated as references; the disk and cylinder were fabricated in one piece using a mold specially made for the present study (group 4). Half the specimens were thermocycled up to 10,000 times in water with a 1-minute dwell time at each temperature (5 degrees C and 55 degrees C). The maximum fracture load values were determined using a universal testing machine (n = 10). The maximum fracture loads for group 3 were significantly enhanced both before and after thermocycling, whereas the maximum fracture loads of group 2 were significantly enhanced before thermocycling (p < 0.05); however, the failure loads decreased for all groups after thermocycling (p < 0.05). All the specimens in groups 1 and 2 debonded during thermocycling. The failure load of group 3 was significantly lower than that of group 4 both before and after thermocycling (p < 0.05). Within the limitations of the current in vitro study, the application and prepolymerization of a mixed dimethacrylate resin liquid prior to the application of a highly filled composite was an effective surface preparation for the polymer-monomer matrix of a fiber-reinforced composite; however, the bond durability may be insufficient.

Spectrophotometric evaluation of the influence of different backgrounds on the color of glass-infiltrated ceramic veneers.

PubMed

Charisis, Dimitrios; Koutayas, Spiridon-Oumvertos; Kamposiora, Photini; Doukoudakis, Asterios

2006-08-01

The purpose of this spectrophotometric study was to evaluate the influence of different color backgrounds on Vita In-Ceram (Vident) glass-infiltrated ceramic veneers. A total of 50 color background disks were fabricated from Vitadur Alpha 2M2 (n=30) and 5M1 (n=20) dentin porcelain (Vi-dent). Ceramic veneer disks were fabricated from In-Ceram Spinell (n=20) or In-Ceram Alumina (n=20) glass-infiltrated core veneered using Vitadur Alpha 2M2 dentin porcelain. In addition, 10 ceramic veneer disks were fabricated from feldspathic dentin porcelain Vitadur Alpha 2M2. The ceramic veneer specimens were bonded onto the color background specimens using dual-curing luting composite cement, creating the following groups (each n=10): S2M2 (Spinell/2M2), S5M1 (Spinell/5M1), A2M2 (Alumina/2M2), A5M1 (Alumina/5M1), and control (Vitadur Alpha/2M2). L*a*b* color coordinates were measured five times for each specimen using a Vita Easyshade (Vident) spectrophotometer. Mean color differences (deltaE) between each study group and the control group were: 3.79 for S2M2; 7.24 for S5M1; 5.86 for A2M2, and 7.32 for A5M1. Two-way ANOVA showed statistically significant differences in deltaE between all groups. However, a t test revealed that the statistically significant differences only existed between groups S2M2/S5M1, A2M2/A5M1, and S2M2/A2M2. The results suggest that vacuum infiltration with a translucent glass provides the Spinell and Alumina ceramic veneers with increased semi-translucency, which makes them highly influenced by discolored backgrounds. In-Ceram Spinell glass-infiltrated ceramic veneers could be considered as an alternative to conventional feldspathic veneers for the restoration of nondiscolored teeth. Although Spinell and Alumina ceramic veneers could enhance the final color establishment of discolored teeth, the results would not be clinically acceptable.

Optical/Infrared properties of Be stars in X-ray Binary systems

NASA Astrophysics Data System (ADS)

Naik, Sachindra

2018-04-01

Be/X-ray binaries, consisting of a Be star and a compact object (neutron star), form the largest subclass of High Mass X-ray Binaries. The orbit of the compact object around the Be star is wide and highly eccentric. Neutron stars in the Be/X-ray binaries are generally quiescent in X-ray emission. Transient X-ray outbursts seen in these objects are thought to be due to the interaction between the compact object and the circumstellar disk of the Be star at the periastron passage. Optical/infrared observations of the companion Be star during these outbursts show that the increase in the X-ray intensity of the neutron star is coupled with the decrease in the optical/infrared flux of the companion star. Apart from the change in optical/infrared flux, dramatic changes in the Be star emission line profiles are also seen during X-ray outbursts. Observational evidences of changes in the emission line profiles and optical/infrared continuum flux along with associated X-ray outbursts from the neutron stars in several Be/X-ray binaries are presented in this paper.

Sifting Through SDO's AIA Cosmic Ray Hits to Find Treasure

NASA Astrophysics Data System (ADS)

Kirk, M. S.; Thompson, B. J.; Viall, N. M.; Young, P. R.

2017-12-01

The Solar Dynamics Observatory's Atmospheric Imaging Assembly (SDO AIA) has revolutionized solar imaging with its high temporal and spatial resolution, unprecedented spatial and temporal coverage, and seven EUV channels. Automated algorithms routinely clean these images to remove cosmic ray intensity spikes as a part of its preprocessing algorithm. We take a novel approach to survey the entire set of AIA "spike" data to identify and group compact brightenings across the entire SDO mission. The AIA team applies a de-spiking algorithm to remove magnetospheric particle impacts on the CCD cameras, but it has been found that compact, intense solar brightenings are often removed as well. We use the spike database to mine the data and form statistics on compact solar brightenings without having to process large volumes of full-disk AIA data. There are approximately 3 trillion "spiked pixels" removed from images over the mission to date. We estimate that 0.001% of those are of solar origin and removed by mistake, giving us a pre-segmented dataset of 30 million events. We explore the implications of these statistics and the physical qualities of the "spikes" of solar origin.

Influence of nano-material on the expansive and shrinkage soil behavior

NASA Astrophysics Data System (ADS)

Taha, Mohd Raihan; Taha, Omer Muhie Eldeen

2012-10-01

This paper presents an experimental study performed on four types of soils mixed with three types of nano-material of different percentages. The expansion and shrinkage tests were conducted to investigate the effect of three type of nano-materials (nano-clay, nano-alumina, and nano-copper) additive on repressing strains in compacted residual soil mixed with different ratios of bentonite (S1 = 0 % bentonite, S2 = 5 % bentonite, S3 = 10 % bentonite, and S4 = 20 % bentonite). The soil specimens were compacted under the condition of maximum dry unit weight and optimum water content ( w opt) using standard compaction test. The physical and mechanical results of the treated samples were determined. The untreated soil values were used as control points for comparison purposes. It was found that with the addition of optimum percentage of nano-material, both the swell strain and shrinkage strain reduced. The results show that nano-material decreases the development of desiccation cracks on the surface of compacted samples without decrease in the hydraulic conductivity.

Titanium compacts produced by the pulvimetallurgical hydride-dehydride method for biomedical applications.

PubMed

Barreiro, M M; Grana, D R; Kokubu, G A; Luppo, M I; Mintzer, S; Vigna, G

2010-04-01

Titanium powder production by the hydride-dehydride method has been developed as a non-expensive process. In this work, commercially pure grade two Ti specimens were hydrogenated. The hydrided material was milled in a planetary mill. The hydrided titanium powder was dehydrided and then sieved to obtain a particle size between 37 and 125 microm in order to compare it with a commercial powder produced by chemical reduction with a particle size lower than 150 microm. Cylindrical green compacts were obtained by uniaxial pressing of the powders at 343 MPa and sintering in vacuum. The powders and the density of sintered compacts were characterized, the oxygen content was measured and in vivo tests were performed in the tibia bones of Wistar rats in order to evaluate their biocompatibility. No differences were observed between the materials which were produced either with powders obtained by the hydride-dehydride method or with commercial powders produced by chemical reduction regarding modifications in compactation, sintering and biological behaviour.

CHARGING AND COAGULATION OF DUST IN PROTOPLANETARY PLASMA ENVIRONMENTS

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

Matthews, L. S.; Land, V.; Hyde, T. W., E-mail: lorin_matthews@baylor.edu

2012-01-01

Combining a particle-particle, particle-cluster, and cluster-cluster agglomeration model with an aggregate charging model, the coagulation and charging of dust particles in plasma environments relevant for protoplanetary disks have been investigated, including the effect of electron depletion in high dust density environments. The results show that charged aggregates tend to grow by adding small particles and clusters to larger particles and clusters, and that cluster-cluster aggregation is significantly more effective than particle-cluster aggregation. Comparisons of the grain structure show that with increasing aggregate charge the compactness factor, {phi}{sub {sigma}}, decreases and has a narrower distribution, indicating a fluffier structure. Neutral aggregatesmore » are more compact, with larger {phi}{sub {sigma}}, and exhibit a larger variation in fluffiness. Overall, increased aggregate charge leads to larger, fluffier, and more massive aggregates.« less

CONSTRAINTS ON MACHO DARK MATTER FROM COMPACT STELLAR SYSTEMS IN ULTRA-FAINT DWARF GALAXIES

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

Brandt, Timothy D.

2016-06-20

I show that a recently discovered star cluster near the center of the ultra-faint dwarf galaxy Eridanus II provides strong constraints on massive compact halo objects (MACHOs) of ≳5 M {sub ⊙} as the main component of dark matter. MACHO dark matter will dynamically heat the cluster, driving it to larger sizes and higher velocity dispersions until it dissolves into its host galaxy. The stars in compact ultra-faint dwarf galaxies themselves will be subject to the same dynamical heating; the survival of at least 10 such galaxies places independent limits on MACHO dark matter of masses ≳10 M {sub ⊙}.more » Both Eri II’s cluster and the compact ultra-faint dwarfs are characterized by stellar masses of just a few thousand M {sub ⊙} and half-light radii of 13 pc (for the cluster) and ∼30 pc (for the ultra-faint dwarfs). These systems close the ∼20–100 M {sub ⊙} window of allowed MACHO dark matter and combine with existing constraints from microlensing, wide binaries, and disk kinematics to rule out dark matter composed entirely of MACHOs from ∼10{sup −7} M {sub ⊙} up to arbitrarily high masses.« less

An Ultraviolet/Optical Atlas of Bright Galaxies

NASA Astrophysics Data System (ADS)

Marcum, Pamela M.; O'Connell, Robert W.; Fanelli, Michael N.; Cornett, Robert H.; Waller, William H.; Bohlin, Ralph C.; Neff, Susan G.; Roberts, Morton S.; Smith, Andrew M.; Cheng, K.-P.; Collins, Nicholas R.; Hennessy, Gregory S.; Hill, Jesse K.; Hill, Robert S.; Hintzen, Paul; Landsman, Wayne B.; Ohl, Raymond G.; Parise, Ronald A.; Smith, Eric P.; Freedman, Wendy L.; Kuchinski, Leslie E.; Madore, Barry; Angione, Ronald; Palma, Christopher; Talbert, Freddie; Stecher, Theodore P.

2001-02-01

We present wide-field imagery and photometry of 43 selected nearby galaxies of all morphological types at ultraviolet and optical wavelengths. The ultraviolet (UV) images, in two broad bands at 1500 and 2500 Å, were obtained using the Ultraviolet Imaging Telescope (UIT) during the Astro-1 Spacelab mission. The UV images have ~3" resolution, and the comparison sets of ground-based CCD images (in one or more of B, V, R, and Hα) have pixel scales and fields of view closely matching the UV frames. The atlas consists of multiband images and plots of UV/optical surface brightness and color profiles. Other associated parameters, such as integrated photometry and half-light radii, are tabulated. In an appendix, we discuss the sensitivity of different wavebands to a galaxy's star formation history in the form of ``history weighting functions'' and emphasize the importance of UV observations as probes of evolution during the past 10-1000 Myr. We find that UV galaxy morphologies are usually significantly different from visible band morphologies as a consequence of spatially inhomogeneous stellar populations. Differences are quite pronounced for systems in the middle range of Hubble types, Sa through Sc, but less so for ellipticals or late-type disks. Normal ellipticals and large spiral bulges are fainter and more compact in the UV. However, they typically exhibit smooth UV profiles with far-UV/optical color gradients which are larger than any at optical/IR wavelengths. The far-UV light in these cases is probably produced by extreme horizontal branch stars and their descendants in the dominant, low-mass, metal-rich population. The cool stars in the large bulges of Sa and Sb spirals fade in the UV while hot OB stars in their disks brighten, such that their Hubble classifications become significantly later. In the far-UV, early-type spirals often appear as peculiar, ringlike systems. In some spiral disks, UV-bright structures closely outline the spiral pattern; in others, the disks can be much more fragmented and chaotic than at optical wavelengths. Contributions by bright active galactic nuclei (AGNs) to the integrated UV light in our sample range from less than 10% to nearly 100%. A number of systems have unusual UV-bright structures in their inner disks, including rings, compact knots, and starburst nuclei, which could easily dominate the UV light in high-redshift analogs. A significant but variable fraction of the far-UV light in spiral disks is diffuse rather than closely concentrated to star-forming regions. Dust in normal spiral disks does not control UV morphologies, even in some highly inclined disk systems. The heaviest extinction is apparently confined to thin layers and the immediate vicinity of young H II complexes; the UV light emerges from thicker star distributions, regions evacuated of dust by photodestruction or winds, or by virtue of strong dust clumpiness. Only in cases where the dust layers are disturbed does dust appear to be a major factor in UV morphology. The UV-bright plume of M82 indicates that dust scattering of UV photons can be important in some cases. In a companion paper, we discuss far-UV data from the Astro-2 mission and optical comparisons for another 35 galaxies, emphasizing face-on spirals.

Effect of surface acid etching on the biaxial flexural strength of two hot-pressed glass ceramics.

PubMed

Hooshmand, Tabassom; Parvizi, Shaghayegh; Keshvad, Alireza

2008-07-01

The purpose of this study was to assess the effect of surface acid etching on the biaxial flexural strength of two hot-pressed glass ceramics reinforced by leucite or lithium disilicate crystals. Forty glass ceramic disks (14-mm diameter, 2-mm thick) consisting of 20 leucite-based ceramic disks (IPS Empress) and 20 lithia disilicate-based ceramic (IPS Empress 2) were produced by hot-pressing technique. All specimens were polished and then cleaned ultrasonically in distilled water. Ten specimens of each ceramic group were then etched with 9% hydrofluoric (HF) acid gel for 2 minutes and cleaned ultrasonically again. The biaxial flexural strength was measured by the piston-on-three-ball test in a universal testing machine. Data based on ten specimens in each group were analyzed by two-way ANOVA (alpha= 0.05). Microstructure of ceramic surfaces before and after acid etching was also examined by a scanning electron microscope. The mean biaxial flexural strength values for each group tested were (in MPa): nonetched IPS Empress = 118.6 +/- 25.5; etched IPS Empress = 102.9 +/- 15.4; nonetched IPS Empress 2 = 283.0 +/- 48.5; and etched IPS Empress 2 = 250.6 +/- 34.6. The results showed that the etching process reduced the biaxial flexural strengths significantly for both ceramic types (p= 0.025). No significant interaction between the ceramic type and etching process was found (p= 0.407). From the results, it was concluded that surface HF acid etching could have a weakening effect on hot-pressed leucite or lithia disilicate-based glass ceramic systems.

Antimicrobial susceptibility pattern of Klebsiella species from Ebonyi State University Teaching Hospital Abakaliki, Nigeria.

PubMed

Akujobi, C N

2005-12-01

Klesiella specie isolated from clinical specimens from Ebonyi State University Teaching Hospital (EBSUTH). Abakakliki were studied to determine the antimicrobial susceptibility pattern. Between January, 2003 and September 2004 a total of 3.600 specimens processed in the routine Medical Microbiology laboratory of EBSUTH, of which 245(6.8%) yielded Klebsiella species, with 84 from out - patients and 161 from in - patients. The number of isolates from various samples were: Urine 126, Sputum 37 Endocervical swab 13, Aspirates 8, High Vaginal Swab 7, Blood 3, Eye Swab, Ear Swab and Cerebrospinal fluid were 2 samples each. Organisms were identified by conventional methods. Antimicrobial susceptibility was done by the disk diffusion methods. The antimicrobial disk used include: Ceftazidime, Cefuroxime, Cefotaxine, Augmentin, Pefloxacin (30ug), Doxycyline (25ug) Genticin (10 ug) Ciprofloacin and Ofloxacin (5ug) each and Erythromycin (15ug). All were Oxoid products. Results were interpreted according to NCCLS criteria. Klebsilla species were isolated mostly from urine specimens (51.4%) followed by wound swabs (18.4%). Antimicrobial susceptibility to various groups drugs used was generally poor. The most sensitive antimicrobial was Ciprofloxacin with 121(49.4%) isolates susceptible to it, followed by Gentamicin with 95 (38.8%) and Ceftazidime with 90(36.7%). Seventeen isolates were multiresistant to all the antimicrobial agents used. The result of this study will help in the empiric therapy of infection caused by Klebsiella species in Ebonyi State University Teaching Hospital, Abakaliki, Nigeria but continuous surverillance of antimicrobial resistance of the organnisn is very necessary in the formulation of a sound antibiotic policy in the hospital.

Changes in chroma of two indirect composite materials polymerized with different polymerization systems.

PubMed

Ayano, Michiya

2012-01-01

This study evaluated chroma change in two composite materials (Sinfony and Pearleste) polymerized with two different systems. Disk specimens were prepared using a metal halide unit (Hyper LII) and an exposure time of 60 to 180 s. The proprietary polymerization systems (Visio and Pearlcure systems) were used as the reference polymerization modes. After storage at 37°C for 24 h, CIE 1976 L*a*b* values were measured by using a dental chroma meter (ShadeEye NCC) with a gray background. The specimens were then immersed in water or tea. Color change from baseline to 4 weeks was evaluated by measuring ΔL*, Δa*, and Δb*, after which ΔE*(ab) values were calculated. The brightness of Sinfony specimens was reduced by tea immersion. The color of both materials shifted to yellow after tea immersion, although color change in Sinfony specimens was greater than that in Pearleste specimens. For both materials, color change was less after polymerization with the metal halide unit. In conclusion, Sinfony polymerized with the Hyper LII unit, and Pearleste polymerized with either system, were stable against discoloration due to tea immersion.

Attacking the information access problem with expert systems

NASA Technical Reports Server (NTRS)

Ragusa, James M.; Orwig, Gary W.

1991-01-01

The results of applications research directed at finding an improved method of storing and accessing information are presented. Twelve microcomputer-based expert systems shells and five laser-optical formats have been studied, and the general and specific methods of interfacing these technologies are being tested in prototype systems. Shell features and interfacing capabilities are discussed, and results from the study of five laser-optical formats are recounted including the video laser, compact, and WORM disks, and laser cards and film. Interfacing, including laser disk device driver interfacing, is discussed and it is pointed out that in order to control the laser device from within the expert systems application, the expert systems shell must be able to access the device driver software. Potential integrated applications are investigated and an initial list is provided including consumer services, travel, law enforcement, human resources, marketing, and education and training.

Active Enhancement of Slow Light Based on Plasmon-Induced Transparency with Gain Materials.

PubMed

Zhang, Zhaojian; Yang, Junbo; He, Xin; Han, Yunxin; Zhang, Jingjing; Huang, Jie; Chen, Dingbo; Xu, Siyu

2018-06-03

As a plasmonic analogue of electromagnetically induced transparency (EIT), plasmon-induced transparency (PIT) has drawn more attention due to its potential of realizing on-chip sensing, slow light and nonlinear effect enhancement. However, the performance of a plasmonic system is always limited by the metal ohmic loss. Here, we numerically report a PIT system with gain materials based on plasmonic metal-insulator-metal waveguide. The corresponding phenomenon can be theoretically analyzed by coupled mode theory (CMT). After filling gain material into a disk cavity, the system intrinsic loss can be compensated by external pump beam, and the PIT can be greatly fueled to achieve a dramatic enhancement of slow light performance. Finally, a double-channel enhanced slow light is introduced by adding a second gain disk cavity. This work paves way for a potential new high-performance slow light device, which can have significant applications for high-compact plasmonic circuits and optical communication.

Cygnus OB2: Star Formation Ugly Duckling Causes a Flap

NASA Astrophysics Data System (ADS)

Drake, Jeremy J.; Wright, Nicholas; Guarcello, Mario

2015-08-01

Cygnus OB2 is one of the largest known OB associations in our Galaxy, with a total stellar mass of 30,000 Msun and boasting an estimated 65 O-type stars and hundreds of OB stars. At a distance of only 1.4kpc, it is also the closest truly massive star forming region and provides a valuable testbed for star and planet formation theory. We have performed a deep stellar census using observations from X-ray to infrared, which has enabled studies of sub-structuring, mass segregation and dynamics, while infrared data reveal a story of protoplanetary disk attrition in an extremely harsh radiation environment. I will discuss how Cygnus OB2 challenges the idea that stars must form in dense, compact clusters, and demonstrates that stars as massive as 100 Msun can form in relatively low-density environments. Convincing evidence of disk photoevaporation poses a potential problem for planet formation and growth in starburst environments.

The Nutating Engine-Prototype Engine Progress Report and Test Results

NASA Technical Reports Server (NTRS)

Meitner, Peter L.; Boruta, Mike

2006-01-01

A prototype of a new, internal combustion (IC) engine concept has been completed. The Nutating Engine features an internal disk nutating (wobbling) on a Z-shaped power shaft. The engine is exceedingly compact, and several times more power dense than any conventional (reciprocating or rotary) IC engine. This paper discusses lessons learned during the prototype engine's development and provides details of its construction. In addition, results of the initial performance tests of the various components, as well as the complete engine, are summarized.

Frontiers of stellar evolution

NASA Technical Reports Server (NTRS)

Lambert, David L. (Editor)

1991-01-01

The present conference discusses theoretical and observational views of star formation, spectroscopic constraints on the evolution of massive stars, very low mass stars and brown dwarfs, asteroseismology, globular clusters as tests of stellar evolution, observational tests of stellar evolution, and mass loss from cool evolved giant stars. Also discussed are white dwarfs and hot subdwarfs, neutron stars and black holes, supernovae from single stars, close binaries with evolved components, accretion disks in interacting binaries, supernovae in binary systems, stellar evolution and galactic chemical evolution, and interacting binaries containing compact components.

Silicon Integrated Cavity Optomechanical Transducer

NASA Astrophysics Data System (ADS)

Zou, Jie; Miao, Houxun; Michels, Thomas; Liu, Yuxiang; Srinivasan, Kartik; Aksyuk, Vladimir

2013-03-01

Cavity optomechanics enables measurements of mechanical motion at the fundamental limits of precision imposed by quantum mechanics. However, the need to align and couple devices to off-chip optical components hinders development, miniaturization and broader application of ultrahigh sensitivity chip-scale optomechanical transducers. Here we demonstrate a fully integrated and optical fiber pigtailed optomechanical transducer with a high Q silicon micro-disk cavity near-field coupled to a nanoscale cantilever. We detect the motion of the cantilever by measuring the resonant frequency shift of the whispering gallery mode of the micro-disk. The sensitivity near the standard quantum limit can be reached with sub-uW optical power. Our on-chip approach combines compactness and stability with great design flexibility: the geometry of the micro-disk and cantilever can be tailored to optimize the mechanical/optical Q factors and tune the mechanical frequency over two orders of magnitudes. Electrical transduction in addition to optical transduction was also demonstrated and both can be used to effectively cool the cantilever. Moreover, cantilevers with sharp tips overhanging the chip edge were fabricated to potentially allow the mechanical cantilever to be coupled to a wide range of off-chip systems, such as spins, DNA, nanostructures and atoms on clean surfaces.

The HI Chronicles of LITTLE THINGS BCDs: VII Zw 403’s External Gas Cloud

NASA Astrophysics Data System (ADS)

Ashley, Trisha L.; Simpson, Caroline E.; Elmegreen, Bruce; Johnson, Megan C.; Pokhrel, Nau Raj

2017-01-01

Blue compact dwarf (BCD) galaxies are characterized by their concentrated bursts of star formation. Yet, for many BCDs, it is unclear what has triggered this activity. VII Zw 403 is a well-known BCD that is relatively isolated from other galaxies. Using the high angular and velocity resolution Very Large Array (VLA) atomic hydrogen (HI) data from the LITTLE THINGS1 survey, we study the detailed kinematics and morphology of VII Zw 403’s HI gas. High sensitivity HI Green Bank Telescope (GBT) observations were also used to search the surrounding area for companion galaxies and extended HI emission, but they did not result in detections of either. The VLA data show a kinematically and morphologically disturbed HI disk. From the VLA HI data cubes, we have separated out most of the emission from what is likely an external gas cloud that is in the line of sight of the HI disk. This external gas cloud appears to be accreting onto the disk and could trigger a future burst of star formation. 1Local Irregulars That Trace Luminosity Extremes, The HI Nearby Galaxy Survey; https://science.nrao.edu/science/surveys/ littlethings

Variable reluctance displacement transducer temperature compensated to 650$sup 0$F

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

None

In pressurized water reactor tests, compact instruments for accurate measurement of small displacements in a 650$sup 0$F environment are often required. In the case of blowdown tests such as the Loss of Fluid Test (LOFT) or Semiscale computer code development tests, not only is the initial environment water at 650$sup 0$F and 2200 psi but it undergoes a severe transient due to depressurization. Since the LOFT and Semiscale tests are run just for the purpose of obtaining data during the depressurization, instruments used to obtain the data must not give false outputs induced by the change in environment. A LOFTmore » rho v$sup 2$ probe and a Semiscale drag disk are described. Each utilizes a variable reluctance transducer (VRT) for indication of the drag-disk location and a torsion bar for drag-disk restoring force. The VRT, in addition to being thermally gain and null offset stable, is fabricated from materials known to be resistant to large nuclear radiation levels and has successfully passed a fast neutron radiation test of 2.7 x 10$sup 17$ nvt without failure. (auth)« less